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Home My WebLink About21210 87th Ave NE_PWD1410_2026 RESIDENTIAL MISCELLANEOUS PERMIT APPLICATION Department of Community& Economic Development City of Arlington• 18204 59th Ave NE •Arlington,WA 98223 • Phone(360)403-3551 RETAIIAPPLICATION ING WA LS,ISTORAGE TANKS, PLAYGROUND EQUIPMENTT,POOLS,HOT TUBS,ETC. Project Address:21210 87th Ave NE, Arlington, WA 98223 Project Description: Existing East Arlington Substation reconstruction and new security fence and gates. Valuation: Estimated at $180,000 Owner:Public Utility District No.1 of Snohomish County/Agent: Tom Hendricks Address: 2320 California Street City:Everett State: WA Zip Code: 98201 Phone: 425-783-5022 (Hendricks' office) Email: tdhendricks@snopud.com Contractor Name:To Be Determined after bidding process and PWC award on July 10, 2018 Address: City: State: Zip Code: Phone: Email: License Number_ Expiration Date: I hereby certify that the above information is correct and that the construction, installation for the above mentioned property will be in accordance with the applicable laws of the City of Arlington and the State of Washington. �� c /-7 �1g Appli ants Signature Date Print Applicants Name FOR STAFF USE ONLY Permit 4 'Accepted By Amount Received Receipt# Date Received DRAINAGE PLAN FOR: EAST ARLINGTON SWITCHING STATION W 431g3 PREPARED BY: SNOHOMISH COUNTY P.U.D. NO. 1 DATE PREPARED: MAY 30, 2018 I I TABLE OF CONTENTS 1.0 PROJECTSUMMARY...........................................................................................................................................1 1.1 PROPERTY DESCRIPTION.................................................................................................................................1 1.2 EXISTING CONDITIONS....................................................................................................................................3 1.2 EXISTING CONDITIONS (Cont.)........................................................................................................................7 1.3 DEVELOPED CONDITIONS ...............................................................................................................................7 2.0 MINIMUM REQUIREMENTS...............................................................................................................................9 2.1 MINIMUM REQUIREMENT#1—Preparation of Stormwater Site Plans.......................................................13 2.2 MINIMUM REQUI REM ENT#2—Stormwater Pollution Prevention Plan (SWPPP)........................................13 2.3 MINIMUM REQUI REM ENT#3—Source Control of Pollution........................................................................13 2.4 MINIMUM REQUI REM ENT#4—Preservation of Natural Drainage Systems and OutfaIIs ...........................14 2.5 MINIMUM REQUI REM ENT#5—On-site Stormwater Management.............................................................14 REFERENCES.........................................................................................................................................................15 APPENDIXA..........................................................................................................................................................16 APPENDIXB..........................................................................................................................................................17 APPENDIXC..........................................................................................................................................................18 ii Drainage Report—East Arlington Substation Order#100002342 1 .0 PROJECT SUMMARY 1.1 PROPERTY DESCRIPTION The project site is located in the Southeast Quarter of the Southwest Quarter of the Northwest Quarter of Section 12,Township 31 North, Range 05 East, W.M. in Snohomish County,Washington. More specifically,the project site is located at 21210 87t"Ave NE in Arlington, WA on tax parcel 31051200200500, where the active PUD East Arlington Substation has existed for more than 70 years. Refer to the following Figures 1 and 2. /PMMNWII wrt¢C�.r �RC3T'Y3•.=.Ze SR.�'�.>'hY_YS:2'i3.4`.<:.C:fi'.L`�.'4.�:" -I'• -• •• •• .• .• -• .' NW 12 31 �..,.... s—ere.,---or,.u■ a ...-,.pk. I.claav---- 1{{I-..— e"""i._..._i ....r..._I...u.r•. ;�.'.�.:..■� ' H1 rwartt. 01tr66ft— us■e )15 j I is _-- I } ■c2{ � �� r a N ail j 1CUN2E AC E TRACT NM1 3 t » 02 » c o 'an7 1■ 14 a ;g 7003 -A Q0 ee » 03 .J 1 e 7-012 D ' A l� : 7.00B�:- 01 I _ 092 o� v00 02 IST Sr It �� i■ PlE ...04 ir ■ n t { NE14 Ic.vi) 11 GLG » N m!a CREEK It u S ■ D1 a,- on ! ACE 1, N us01 s2417 qLAAF 00 1 ,rs -�' ■ �+ g N a zam / a - - - . „ MAPLE ST - - - - - + oc t r ,•t1 m: i ✓ H"im ro T i(..2) m a i .040 Io _ _= - - F. f.ASrACF IIED"CAL 3 P4 1, 1. ' TM■ 1 Y-• 11 �:t_n't,e CONDO 8016 P,AT OD GLEN a PU•f''�� - "7 111, 06 ____-- CONDO t104") c") ..:'•'- :-� { { • ---KN e■OJ7070 - BLA 7- -0Q7BlA PM 1 .OM . 2001 tfATf AO 1 OM 2 '/Ma ' � t■t IS N TLE! -:•il "''�r 51I)IM Thar a ■ea a 11 f ict 21271E-ST-CIE 7 V"MEDiGASE S CENTER P�9� ON ID1Z7y t. � � h'tFS1EY ST ( r j aMl•17.31ae FIGURE 1 - QUARTER SECTION MAP Page 1 ' A N'Alcazar Ave anv-uo15 'LISer h-NJi � Wjai _-- a,V weu..-� H-tLeyul O S U.' r -� - — a�,H{�oalaeVV S �Do°. o • i ' [P �� r lslt� r oidw4 m 'J w y �- IitS 0= Y R {` 02 �, P<y-ouiuuo NE— Drainage Report—East Arlington Substation Order#100002342 1.2 EXISTING CONDITIONS The generally flat existing substation property is 1.66 acres in size and is bordered on the south by 2121h St NE (Tviet Road), on the east by 871h Ave NE, on the north by the Navy's Area 51 Substation, and to the west a 100 foot wide Puget Sound Energy transmission easement that crosses the western portion of the property. The eastern 75%of the property contains the developed electrical substation site and the western 25% is covered with native shrubs and emergent species. Refer to the site aerial photo in Figure 3 and the 2016 topographic survey in Figure 4 on pages 4 and 5 respectively. The existing substation contains two 115 kV circuit breakers with associated switches and bus work; two 115 kV to 12.7 kV distribution power transformers; one 12 kV to 55 kV distribution power transformer;ten 15 kV circuit breakers; one 69 kV circuit breaker; and associated switches, bus work, control equipment, etc. In December 2017 the eight 12.7 kV distribution circuits were cut over to the new Eagle Creek Substation across 2121h St NE to the south leaving the 115 kV and 55 kV equipment that will be de-energized and demolished starting in April 2018 . Direct precipitation and tributary upstream slopes are the current source of on-site stormwater. Upstream runoff currently bypasses the substation site in a grass-lined swale to the west of the existing substation fence and enters an 18 inch CMP near the southwest substation fence corner that turns and extends eastward along the north side of 2121h St NE to a city catch basin at the intersection with 871h Ave NE, which discharges eastward through a 12 inch CPP into Eagle Creek. This existing drainage condition will remain unchanged after the proposed development. Currently any stormwater inside the substation yard that doesn't infiltrate into the substation gravel and native subgrade is gathered in perforated pipe underneath the cable trench and is collected in an oil separator basin near the southeast corner of the site, which discharges through an oil trap to the previously mentioned city catch basin at the intersection of 212th St NE and 87th Ave NE. The existing cable trench, pull boxes, and oil separator basin will be demolished but the discharge pipe will be intercepted and utilized for the drainage of the proposed asphalt pavement driveway and the overflow outlet for the interceptor trench underdrain system. Referencing the Critical Area Determination Report prepared for the project by Wetland Resources, Inc. in July 2016 (revised on January 25, 2017) and Figure 5 on page 6; Eagle Creek and two Category II Wetlands A and B lie to the east with buffers that extend onto the site, and a potential Category III Wetland C lies to the north with a buffer that extends onto the site. The grass-lined swale along the west side of the substation was constructed to convey drainage around the substation site from what appears to be a Category III wetland off-site to the north. As an intentionally constructed grass-lined drainage swale, constructed from a non-wetland site, it does not meet the definition of wetland under Arlington Municipal Code (AMC) 20.93.100 and is an unregulated drainage facility. The ground cover on the substation site is almost all gravel surfacing and concrete foundations with some areas of arborvitae trees along the east and south fence lines. The western 25%of the property is a transmission line easement that is not in the area of construction and covered with vegetation that is regularly maintained. Wetland Resources has identified an upstream basin to the north contributing to the potential Category III wetland that accounts for some descending slopes in the transmission line easement area. Seasonal flow has been observed in the grass-lined Swale to the west of the existing substation flowing into the previously mentioned 18 inch diameter CMP. Grades in the existing substation yard generally descend from northwest to southeast with the local high elevation of 162 feet in a small area of the northwest corner of the existing yard and the low of 156 feet in the southeast corner of the property outside the fence. The buffers from Wetlands A, B, and C would technically cast onto the existing substation property, however,the East Arlington Substation was legally established prior to the adoption of AMC 20.88 or 20.93, so it is considered legal nonconforming use. The proposed redevelopment of the substation into a switching station will not change the extent of nonconformity as no expansion of the developed area will occur. Page 3 Drainage Report—East Arlington Substation Order#100002342 , ,ww. Ire ' 77 Tt �r�.d•l.. - 14 - Sal /� J'..S i� `- ��,, ..,{ ♦� .1�'iw� ., tl? � ` � V-41 �♦" . f ¢ �,t t;i _ . Y � r Ir R r • , s _ IL, � FIGURE 3 - EXISTING CONDITIONS Page 4 Drainage Report—East Arlington Substation Order#100002342 jt JIMAas Ott tg lit que a t El El --------------------- 1-1 El z b C3 C[� E- co 0 0 0 0 C4 13 -0 0 0a 13 El 0 - 0 ❑E- el. El c4 z —————————————— ----------------- cn Z 77 V v I A �4 0 4 0 [5 FIGURE 4- EXISTING CONDITIONS Page 5 Drainage r•rt—East Arlingtonr r ► Order#100002342 ow r ' CAT7 GORY ilt � ABITAT SCORE 5 � � A Y 140 BUFFER �[�• T f - (33°!o ABOVE STANDAR At ddmw FIGURE 5 EXISTING CONDITIONS Page 6 -� i _ -- WETLAND B I SUBSTA 1 LEGAL _ ' ' > ATEGORY II __ -CONFORMiN M ABITAT SCORE 8 �w U$E 299'BUFFER � � (33%ABOVE ST D�RD ` ' _ PROPOSED—� a YVETLAND A GLE CREEK -'� -'�-• �-- CATEGORY II - SUBSTATION � � `� ABITAT SCORE 7 - 219'BUFFER :; �' '► (33%ABOVE STANDARDf '�(•�: ' • ' LEGAL -'�` � � NON-CONFORMING-----. .. ' ..r TYPE F �I � � %- mil►_ r - Drainage Report—East Arlington Substation Order#100002342 1.2 EXISTING CONDITIONS (Cont.) Zipper Geo Associates, LLC has prepared a geotechnical report for the site titled Geotechnical Engineering Report, East Arlington Substation Site Improvements dated September 15, 2016. This geotechnical report is in addition to an existing January 31, 1991 Dames & Moore geotechnical report for the site titled Report of Geotechnical Investigation proposed Arlington Substation Addition Arlington, Washington. With the exception of the northwest corner,the entire yard is surfaced with coarse gravel-size crushed rock. Surfacing in the northwest corner consists of gravelly sand and quarry spalls. The thickness of the fill varied across the yard from about 2 feet to 7.5 feet in depth with characteristics varying from medium dense silty gravel to medium dense to very dense gravelly sand. Native soils observed below the surficial fill material generally consisted of medium dense to very dense silty sand with variable gravel content. The US Department of Agriculture's Soil Survey of Snohomish County Area Washington has the on-site soils mapped mostly as Everett very gravelly sandy loam, with 0 to 8 percent slopes. The 2016 geotechnical report states the Geologic Map of the Arlington East Quadrangle, Snohomish County, Washington describes the site as underlain by the Marysville Sand member of recessional outwash deposits. However, based upon the condition disclosed by the boring completed on the site, it appears that the native soils are more representative of the glacial till which has been mapped to the southeast and northwest of the site and underlies the recessional deposits. 1.3 DEVELOPED CONDITIONS This project involves the demolition of the existing PUD East Arlington Substation and the reconstruction of a new six breaker 115 kV ring bus switching station. The entire existing substation site will be redeveloped with new foundations and equipment including a new fence with enhanced maintenance access from 2121h St NE and from 871h Ave NE. Refer to Figure 6 on page 8. The north fence common with the Navy Area 51 yard will remain unchanged and the new west fence line will be constructed in the same location as the existing fence. The east fence line will be relocated westerly to allow for a land dedication to the City of Arlington of the east 12 feet of the property with a 30 foot radius curve near the new southeast fence corner for improved turning radius from 871h Ave NE onto 2121h St NE. The southeast corner of the substation property has been redesigned to incorporate the existing gravel parking area into the substation yard inside the new security fence. Upstream runoff currently bypasses the substation site in a grass-lined Swale to the west of the existing substation fence and enters an 18" CMP near the southwest substation fence corner that turns and extends eastward along the north side of 212th St NE to a city catch basin at the intersection with 87th Ave NE discharging eastward into Eagle Creek. This existing bypass condition is outside the proposed construction area and will remain unchanged after the proposed development. For the substation redevelopment the site runoff is intended to be infiltrated through the substation gravel or into the landscaping areas. Precipitation falling within the substation yard will infiltrate through the imported crushed rock fill layer and then at a relatively slower rate will infiltrate into the native soil below. The imported crushed rock base and interceptor trench will act as a reservoir, retaining water during intense rainfall events. Water runoff from landscaped areas will drain naturally. The only potential pollution generating surface proposed is the approximately 700-SF main access driveway paved with asphalt near the southeast fence corner. The substation is not a staffed facility. Trips to the substation are made for operation and maintenance activities estimated as bimonthly, so treatment is not proposed since the site will not see customary vehicle traffic. The driveway provides area for one off-street parking space in front of the personnel gate. The substation yard is a drivable surface; however, use is infrequent and only used by District utility vehicles and or heavy hauling/ heavy lifting equipment for major repairs and or electrical equipment upgrades. Also note, District vehicles are serviced and maintained regularly by the District's Transportation Department,thus providing further pollution prevention. Therefore, the substation yard is not considered a pollution generating surface. Page 7 Drainage Report—East Arlington Substation Order#100002342 -W-Z < T, IAV H.Lfp 13 -------- - ---------- 33r ...... ------ "al El 13, :0 01 1A LLA za 93 v! A J1 -el ............ 0 C3 ILE------I El al > 1 4 t __ 41) ......................14 ..................................... .................... ..................... 1yl= FIGURE 6- DEVELOPED CONDITIONS Page 8 Drainage Report—East Arlington Substation Order#100002342 2 . 0 MINIMUM REQUIREMENTS The drainage design for the project has been prepared based on the requirements of the 2012/14 Department of Ecology Stormwater Management Manual for Western Washington (DOE Manual) as adopted by the City of Arlington. WWHM2012 as provided by DOE has been used for determining basin runoff and for sizing of the stormwater facilities. The Flow Chart for Determining Requirements for New Development, which is Figure 1-2.4.1 of the DOE Manual and included as Figure 6 on page 11,was used to determine the applicable Minimum Requirements. The following bullets provide a narrative for each step of the flowchart: • The site does NOT have 35%or more of existing impervious coverage. The existing impervious surfaces are calculated to be 12,890 SF and only 23.67% of the 1.25 acres currently developed. • The project will NOT result in 5,000 SF of new plus replaced hard surface area. The proposed impervious surfaces (or hard surface area) will be almost three times less than existing and is calculated to be 4,396 SF. • The project does NOT convert%acres or more of vegetation to lawn or landscaped areas, or convert 2.5 acres or more of native vegetation to pasture. Only the existing developed substation area will be effected by the proposed development. • The project WILL result in 2,000 SF, or greater, of new plus replaced hard surface area. As previously stated the proposed development will result in approximately 4,396 SF of new or replaced hard surfaces. Therefore Minimum Requirements#1 through#5 apply to the new and replaced hard surfaces and the land disturbed. The Flow Chart for Determining Requirements for Redevelopment, which is DOE Figure 1-2.4.2 and included as Figure 7 on page 12,yielded the same Minimum Requirements outlined as follows: • The project does result in 2,000 SF, or more, of new plus replaced hard surface area; and the land disturbing activity totals 7,000 SF or greater. • Minimum Requirements#1 through#5 apply to the new and replaced hard surfaces and the land disturbed. • The project does NOT add 5,000 SF or more of new hard surfaces, NOR converts%acres or more of vegetation to lawn or landscaped areas, NOR converts 2.5 acres or more of native vegetation to pasture. • The project is NOT a road related project. • The total of new plus replaced hard surfaces is less than 5,000 SF. Therefore Minimum Requirements#1 through#5 apply to the new and replaced hard surfaces and the land disturbed and no additional requirements are necessary. The proposed redevelopment activity will replace the 12,890 SF of existing impervious surface with 4,396 SF of impervious surface; convert 5,899 SF of impervious surface to substation yard and gravel perimeter area; and will replace the existing 2,528 SF of landscaping with 5,122 SF of new landscaping, adding 2,595 SF of landscaping area. The replaced impervious surfaces will be a combination of gravel surfacing and asphalt pavement for the driveways, concrete foundations and slabs for electrical equipment, and concrete curbing for the fence and gravel perimeter areas. The substation yard and gravel perimeter do not function as an impervious surface and is described as follows: Page 9 Drainage Report—East Arlington Substation Order#100002342 o The substation yard (the area inside the substation security fence) and a 3-ft wide gravel perimeter outside the security fence will be surfaced with substation rock(crushed rock). The rock surface provides a layer of resistance to help reduce the risk of step and touch potential; minimize weed growth; provide a clean and reasonably dry surface during wet periods; and dissipates erosions effect from rain. Substation rock is a poorly graded mix of crushed rock ranging from 1 inch to 3/8 inch with fines content of less than 1.5%. Substation rock is placed 4 inches deep across the surface of the substation yard and 3-ft perimeter. In place, substation rock has a minimum void ratio of 0.30. o The substation rock will be underlain with 14 inches of Crushed Surfacing Base Course (CSBC) meeting the gradation and quality criteria in WSDOT Standard Specification 9-09.9(3). Zipper Geo Associates tested a sample of CSBC from Cal Portland of Everett,WA, and completed a permeability test. The sample was compacted to approximately 95%of the modified Proctor maximum dry density in order to replicate its condition in the substation and tested for permeability via the ASTM D 2434 methodology. The sample was found to have a saturated hydraulic conductivity of 2.2 x 10-2 cm/sec or 30.8 inches per hour. In the past the District has had laboratory testing completed on CSBC sourced from the Iron Mountain Quarry in Granite Falls, WA. Samples of this material have been shown to have a permeability of 130 inches/hour and void ratio of over 40. The preferred Iron Mountain Quarry products are 100%crushed rock and no naturally occurring sand is blended with crushed rock to produce the finished product. Refer to page 22 and 23 of the Geotechnical Engineering Report. o Before imported granular fill materials are placed, the existing substation equipment, structures, and conductor will be removed. Then all of the concrete foundations and slabs; underground conduit, pipe, cable trench, and grounding conductor will be demolished and removed. Any void spaces created by removing deep foundations will be backfilled with compacted structural fill, Controlled Density Fill (CDF), or lean mix concrete. Existing fill material will be kept onsite and reused as much as possible, but any existing fill material deemed unsuitable for use as subgrade material by the geotechnical consultant onsite during excavation will be removed and replaced with imported structural fill or CSBC. The finished grade of the substation yard will be very close to the existing grade, so extensive grading will not be required. The subgrade will be proof-rolled to a firm non-yielding condition prior to granular fill placement. Refer to pages 6 through 9 of the Geotechnical Engineering Report. o In conclusion,the substation yard and gravel perimeter will not function as an impervious surface. Rainfall landing on the crushed rock surface will infiltrate the substation rock, CSBC, and infiltrate into the underlying native soil. The WWHM 12 software was used to model the substation site with the drainage characteristics described above. The results of the model demonstrate that 100%of the total rainfall within the substation yard and gravel perimeter will infiltrate. Page 10 Drainage Report—East Arlington Substation Order#100002342 Start Here Does the site have 35% Yes See Redevelopment Minimum or more of existing 0 Requirements and Flow Chart impervious coverage? (Figure 1-2.4.2). No Does the project convertIF acres or more of vegetation to Does the project result in lawn or landscaped areas, or 5,000 square feet, or No convert 2.5 acres or more of greater, of new plus native vegetation to pasture? replaced hard surface area? No Yes Yes Does the project result in 2,000 IF square feet, or greater, of new plus All Minimum Requirements replaced hard surface area? apply to the new and replaced hard surfaces and converted vegetation areas. Yes , No Does the project have land Minimum Requirements #1 disturbing activities of 7,000 through #5 apply to the new Yes square feet or greater? and replaced hard surfaces and the land disturbed. No Minimum Requirement#2 applies. Figure 1-2.4. 1 Flow Chart for Determining Requirements for Ne,.,^✓ Development DEPARTMENT OF Revised June 2015 ECOLOGYPlease see http iAvww.ecy.wo.gov/copynght.hbnl for copyright notice including permissions, State of 'Aashingtor, limitation of liability and disclaimer_ FIGURE 7 - DOE FIGURE 1-2.4.1 Page 11 Drainage Report—East Arlington Substation Order#100002342 Does the project result in 2,000 square feet, or more, of new plus replaced hard surface area? OR Does the land disturbing activity total 7,000 square feet or greater? Yes No Minimum Requirements #1 through#5 apply to the new and replaced hard Minimum Requirement#2 applies. surfaces and the land disturbed. Next Question Does the project add 5,000 square feet or more of new hard surfaces? OR Convert 3,4 acres or more of vegetation to lawn or landscaped areas? OR Convert 2.5 acres or more of native vegetation to pasture? Yes No All Minimum Requirements apply Next Question to the new hard surfaces and the Is this a road converted vegetation areas. related project? No Yes Does the project add 5,000 square feet or more of new hard surfaces? Yes No Is the total of new plus replaced hard surfaces Do the new hard I F 5,000 square feet or more, surfaces add 50%or No No additional No AND more to the existing does the value of the proposed improvements hard surfaces within requirements. - including intenor improvements- exceed the project limits? 50% of the assessed value (or replacement value)of the existing site improvements? Yes All Minimum Requirements apply to the new and replaced hard surfaces and converted vegetation areas. Yes Figure 1-2.4.2 Flow Chart for Determining Requirements for Redevelopment CEPAR7N'EI.T C:F Revised June2015 ECOLOGYPlease see http--IAvww.ecy.wo.gov/copynghthbnl for cooyright notice including permissions, =ta.t r,tr_'rI limitation of liability and disclaimer_ FIGURE 8 — DOE FIGURE 1-2.4.2 Page 12 Drainage Report—East Arlington Substation Order#100002342 2.1 MINIMUM RE QU I REM ENT #1 — Preparation of Stormwater Site Plans To comply with Minimum Requirement#1, information and analysis of the existing site conditions, a site development layout, and an off-site analysis are provided in the following documents. The plans and reports are prepared in accordance with AMC 13.28. • Proposed Site Plan, prepared by Snohomish County PUD. Supporting boundary and topographic survey provided by Harmsen &Associates, Inc. • Conceptual SWPP Plan, prepared by Snohomish County PUD. • Conceptual Grading and Drainage Plan, prepared by Snohomish County PUD. • Targeted Drainage Report, prepared by Snohomish County PUD. • Critical Areas Determination Report, prepared by Wetland Resources, Inc. • Geotechnical Engineering Report, prepared by Zipper Geo Associates. • Conceptual Landscape Plans,TBD and prepared by Snohomish County PUD. 2.2 MINIMUM REQUIREMENT #2 —Stormwater Pollution Prevention Plan (SWPPP) A SWPPP is required for the proposed redevelopment activity. The SWPPP consists of two parts;the plan, and the narrative. The SWPP Plan is provided in the plan set and the narrative portion is addressed in a separate SWPPP report. The narrative addresses all thirteen elements described in AMC 13.28.150. Site disturbance will exceed the 1.0- acre threshold;therefore, coverage under the Department of Ecology's Construction Stormwater General Permit is required and will be obtained by the District. 2.3 MINIMUM REQUIREMENT #3 — Source Control of Pollution The redeveloped East Arlington Substation will have no large distribution power transformers each containing up to 8200 gallons of insulating mineral oil, since the distribution circuits are now originating from the new Eagle Creek Substation across the street. The upgraded 115 kV switchyard will have eighteen electromagnetic voltage transformers (EMVT) each containing approximately 60 gallons of insulating mineral oil and the single station service transformer(SST)will contain about 80 gallons of insulating mineral oil for a total amount of insulating mineral oil of 1,160 gallons. The insulating oil is highly refined mineral oil that is essentially equivalent to food grade oil except for color. Oil pollution prevention is regulated under Federal Regulation 40 CFR Part 112. This part establishes procedures, methods, equipment, and other requirements to prevent the discharge of oil into or upon navigable waters of the United States. As required by federal and state law, oil storage of 1,320-gallons or more requires the owner of said facility to have a Spill Prevention Control and Countermeasure Plan (SPCC Plan). Substation facilities are designed to contain the release of mineral insulating oil. The District has an SPCC Plan for each of its substation facilities and the existing SPCC Plan for this substation will be revised to account for the redevelopment changes. Any catastrophic failure of an EMVT or SST could result in insulating oil spilling onto the crushed rock surfacing inside the substation yard. The yard consists of highly permeable crushed rock placed over a highly permeable crushed rock base. Void space within the crushed rock exceeds 30%. Native subgrade soils have low permeability, thus allowing the crushed rock to act as a reservoir, containing the oil on- site. Should this failure occur the SPCC Plan will be implemented and cleanup will commence. A loss of oil to ground and surface waters is not likely to occur prior to emergency response teams arriving at the site. Page 13 Drainage Report—East Arlington Substation Order#100002342 Snohomish PUD has an agency wide Spill Prevention, Control and Countermeasure (SPCC) Plan in place, as part of the Clean Water Act section 401 compliance. The response measures outlined in the SPCC Plan are intended to prevent any oil from leaving the site. Remote sensing devices will alert dispatchers to an oil leak or equipment failure, and emergency personnel will be directed to the station. 2.4 MINIMUM REQUIREMENT #4 — Preservation of Natural Drainage Systems and Outfalls The proposed redevelopment will not alter the existing drainage pattern. Up-slope runoff from the northwest will continue to bypass the substation in the grass-lined swale to the west of the substation and will enter the 18 inch CMP near the southwest fence corner and flow to the City catch basin at the intersection of 212t"St NE and 87t"Ave NE, eventually flowing into Eagle Creek. Rainfall within the substation yard will infiltrate in-place. The perimeter interceptor trench inside the substation yard will have an emergency overflow pipe connected to the existing storm drain pipe connected to the previously mentioned City catch basin in the event rainfall exceeds the infiltrating capacity/retention capacity of the underlying native soil/crushed rock base. Water runoff from landscaped areas will drain naturally. 2.5 MINIMUM REQUIREMENT #5 — On-site Stormwater Management The intent of the on-site stormwater management BMP's proposed is to infiltrate, disperse, and retain stormwater runoff on-site to the maximum extent feasible without causing flooding or erosion impacts. The proposed on-site stormwater management system consists of on-site infiltration within the substation yard and gravel perimeter. As described in detail in Section 2.0,the proposed substation site is underlain by native soils consisting of medium dense to very dense silty sand with variable gravel content (glacial till). Utilizing the entire substation yard foot print to infiltrate stormwater makes infiltration an effective means for disposing of stormwater. Zipper Geo Associates states the saturated hydraulic conductivity values of the site's granular soils may be considered favorable for stormwater infiltration and recommends using a functional long-term infiltration rate of 1.63 inches/hour for the substation yard subgrade. The redevelopment plan is to excavate the existing substation's gravel surface down to the top of subgrade elevation and backfill with 14 inches of CSBC topped off with 4 inches of substation rock to make final grade elevation. As described earlier,the CSBC has adequate void space in its compacted state for stormwater retention. The specified CSBC will have a minimum void ratio of 0.40. The entire site was modeled using WWHM2012. The substation yard and gravel perimeter were modeled as impervious surfaces to mimic rainfall landing within the yard passing directly to the underlying native soil. The results of the model demonstrate the substation yard and perimeter gravel area will infiltrate 100%of rainfall within its respective basin. Page 14 Drainage Report—East Arlington Substation Order#100002342 REFERENCES Arlington Municipal Code-Chapter 13.28-Stormwater Utility. Department of Ecology, State of Washington -2012 Stormwater Management Manual for Western Washington as Amended in December 2014. Zipper Geo Associates, LLC(September 15, 2016). Geotechnical Engineering Report East Arlington Substation Site. U.S.D.A. Natural Resources Conservation Service. (n.d.). Web Soil Survey. Retrieved December, 2017,from http://websoilsurvey.nres.usda.gov/app/WebSoilSurvey.aspx U.S.D.A. Soil Conservation Service. (1983).Soil Survey of Snohomish County Area Washington. Wetland Resources, Inc. (July 2016, revised on January 25,2017). Critical Area Determination Report for Snohomish County PUD No. 1, East Arlington and Eagle Creek Substations. Page 15 Drainage Report—East Arlington Substation Order#100002342 APPENDIX A USDA Natural Resources Conservation Service,Web Soil Survey Page 16 USDA United States A product of the National Custom Soil Resource Department of Cooperative Soil Survey, Agriculture a joint effort of the United Report for RCS States Department of n II V Agriculture and other Snohomish County v Federal agencies, State Natural agencies including the Area, Washington Resources Agricultural Experiment Conservation Stations, and local Service participants East Arlington Substation t► dil l �1 rpo' it December 7, 2017 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nres.usda.gov/wps/ portal/nres/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nres)or your NRCS State Soil Scientist(http://www.nres.usda.gov/wps/portal/nres/detail/soils/contactus/? cid=nres142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice)or(202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 SoilMap.................................................................................................................. 8 SoilMap................................................................................................................9 Legend................................................................................................................10 MapUnit Legend................................................................................................ 11 MapUnit Descriptions.........................................................................................11 Snohomish County Area, Washington............................................................ 13 4—Alderwood-Everett gravelly sandy loams, 25 to 70 percent slopes....... 13 17—Everett very gravelly sandy loam, 0 to 8 percent slopes..................... 14 39—Norma loam......................................................................................... 16 57—Ragnar fine sandy loam, 0 to 8 percent slopes................................... 17 References............................................................................................................19 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 Custom Soil Resource Report scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and 6 Custom Soil Resource Report identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. 7 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 Custom Soil Resource Report 3 Soil Map 3 a 565840 56030 5658M 5659W 565M 565940 565960 565%0 5660M 566020 48°11'19"N 48°11'19"N II 48°11'15"N I 48°11'15'N 565840 565860 565880 565900 565920 565940 565960 565980 566000 566020 ir$ 3 3 N Map Scale:1:856 if printed on A landscape(11"x 8.5")sheet. Meters N 0 10 20 40 60 Feet 0 40 80 160 240 Map projection:Web Mercator Comer coordinates:WGS84 Edge tics:UTM Zone 1ON WGS84 9 Custom Soil Resource Report MAP LEGEND MAP INFORMATION Area of Interest(AOI) Ig Spoil Area The soil surveys that comprise your AOI were mapped at 0 Area of Interest(AOI) Q Stony Spot 1:24,000. Soils Very Stony Spot 0 Soil Map Unit Polygons Warning:Soil Map may not be valid at this scale. ,. Wet Spot 60 Soil Map Unit Lines Enlargement of maps beyond the scale of mapping can cause p other misunderstanding of the detail of mapping and accuracy of soil p Soil Map Unit Points g pp� g Y .� Special Line Features line placement.The maps do not show the small areas of Special Point Features contrasting soils that could have been shown at a more detailed V Blowout Water Features scale. —_- Streams and Canals Borrow Pit Transportation Please rely on the bar scale on each map sheet for map Clay Spot Rails measurements. Q Closed Depression .%/ Interstate Highways Gravel Pit Source of Map: Natural Resources Conservation Service .r US Routes Web Soil Survey URL: Gravelly Spot Major Roads Coordinate System: Web Mercator(EPSG:3857) ® Landfill Local Roads Maps from the Web Soil Survey are based on the Web Mercator Lava Flow Background projection,which preserves direction and shape but distorts distance and area.A projection that preserves area,such as the 41& Marsh or swamp Aerial Photography Albers equal-area conic projection,should be used if more eR► Mine or quarry accurate calculations of distance or area are required. Miscellaneous Water This product is generated from the USDA-NRCS certified data as Q Perennial Water of the version date(s)listed below. V Rock Outcrop Soil Survey Area: Snohomish County Area,Washington + Saline Spot Survey Area Data: Version 17,Nov 22,2017 Sandy Spot Soil map units are labeled(as space allows)for map scales Severely Eroded Spot 1:50,000 or larger. Sinkhole Date(s)aerial images were photographed: Mar 29,2016—Oct Slide or Slip 10,2016 oa Sodic Spot The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps.As a result,some minor shifting of map unit boundaries may be evident. 10 Custom Soil Resource Report Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 4 Alderwood-Everett gravelly 0.0 0.1% sandy loams,25 to 70 percent slopes 17 Everett very gravelly sandy 3.0 76.4% loam,0 to 8 percent slopes 39 Norma loam 0.7 16.8% 57 Ragnar fine sandy loam,0 to 8 0.3 6.7% percent slopes Totals for Area of Interest 3.9 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. 11 Custom Soil Resource Report The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. 12 Custom Soil Resource Report Snohomish County Area, Washington 4—Alderwood-Everett gravelly sandy loams, 25 to 70 percent slopes Map Unit Setting National map unit symbol: 2hyy Elevation: 50 to 800 feet Mean annual precipitation: 25 to 60 inches Mean annual air temperature: 48 to 52 degrees F Frost-free period: 180 to 220 days Farmland classification: Not prime farmland Map Unit Composition Alderwood and similar soils: 60 percent Everett and similar soils: 25 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Alderwood Setting Landform: Till plains Parent material: Basal till Typical profile H1 - 0 to 7 inches: gravelly ashy sandy loam H2- 7 to 35 inches: very gravelly ashy sandy loam H3-35 to 60 inches: gravelly sandy loam Properties and qualities Slope: 25 to 70 percent Depth to restrictive feature: 20 to 40 inches to densic material Natural drainage class: Moderately well drained Capacity of the most limiting layer to transmit water(Ksat): Very low to moderately low(0.00 to 0.06 in/hr) Depth to water table: About 18 to 36 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low(about 3.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7e Hydrologic Soil Group: B Hydric soil rating: No Description of Everett Setting Landform: Terraces, plains Parent material: Glacial outwash Typical profile H1 - 0 to 6 inches: gravelly ashy sandy loam H2- 6 to 18 inches: very gravelly ashy sandy loam H3- 18 to 60 inches: extremely gravelly sand 13 Custom Soil Resource Report Properties and qualities Slope: 25 to 70 percent Depth to restrictive feature: 14 to 20 inches to strongly contrasting textural stratification Natural drainage class: Somewhat excessively drained Capacity of the most limiting layer to transmit water(Ksat): High (1.98 to 5.95 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Very low(about 2.1 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7e Hydrologic Soil Group: A Hydric soil rating: No Minor Components Mckenna Percent of map unit: 5 percent Landform: Depressions Other vegetative classification: Wet Soils (G002XN102WA) Hydric soil rating: Yes Norma, undrained Percent of map unit: 5 percent Landform: Depressions Other vegetative classification: Wet Soils (G002XN102WA) Hydric soil rating: Yes Terric medisaprists, undrained Percent of map unit: 5 percent Landform: Depressions Other vegetative classification: Wet Soils (G002XN102WA) Hydric soil rating: Yes 17—Everett very gravelly sandy loam, 0 to 8 percent slopes Map Unit Setting National map unit symbol: 2t629 Elevation: 30 to 900 feet Mean annual precipitation: 35 to 91 inches Mean annual air temperature: 48 to 52 degrees F Frost-free period: 180 to 240 days Farmland classification: Farmland of statewide importance 14 Custom Soil Resource Report Map Unit Composition Everett and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Everett Setting Landform: Eskers, moraines, kames Landform position (two-dimensional): Summit, shoulder Landform position (three-dimensional): Crest, interfluve Down-slope shape: Convex Across-slope shape: Convex Parent material: Sandy and gravelly glacial outwash Typical profile Oi-0 to 1 inches: slightly decomposed plant material A - 1 to 3 inches: very gravelly sandy loam Bw-3 to 24 inches: very gravelly sandy loam C1 - 24 to 35 inches: very gravelly loamy sand C2-35 to 60 inches: extremely cobbly coarse sand Properties and qualities Slope: 0 to 8 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Somewhat excessively drained Capacity of the most limiting layer to transmit water(Ksat): High (1.98 to 5.95 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low(about 3.2 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4s Hydrologic Soil Group: A Other vegetative classification: Droughty Soils (G002XN402WA), Droughty Soils (G002XF403WA), Droughty Soils (G002XS401 WA) Hydric soil rating: No Minor Components Alderwood Percent of map unit: 10 percent Landform: Ridges, hills Landform position (two-dimensional): Summit Landform position (three-dimensional): Crest, talf Down-slope shape: Linear, convex Across-slope shape: Convex Hydric soil rating: No Indianola Percent of map unit: 10 percent Landform: Eskers, kames, terraces Landform position (three-dimensional): Tread 15 Custom Soil Resource Report Down-slope shape: Linear Across-slope shape: Linear Hydric soil rating: No 39—Norma loam Map Unit Setting National map unit symbol: 2hyx Elevation: 0 to 1,000 feet Mean annual precipitation: 35 to 60 inches Mean annual air temperature: 48 to 52 degrees F Frost-free period: 150 to 200 days Farmland classification: Prime farmland if drained Map Unit Composition Norma, undrained, and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Norma, Undrained Setting Landform: Depressions, drainageways Parent material: Alluvium Typical profile H1 - 0 to 10 inches: ashy loam H2- 10 to 28 inches: sandy loam H3- 28 to 60 inches: sandy loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Poorly drained Capacity of the most limiting layer to transmit water(Ksat): Moderately high to high (0.57 to 1.98 in/hr) Depth to water table: About 0 inches Frequency of flooding: None Frequency of ponding: Frequent Available water storage in profile: Moderate (about 9.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 5w Hydrologic Soil Group: B/D Other vegetative classification: Wet Soils (G002XN102WA) Hydric soil rating: Yes 16 Custom Soil Resource Report Minor Components Bellingham, undrained Percent of map unit: 5 percent Landform: Depressions Other vegetative classification: Wet Soils (G002XN102WA) Hydric soil rating: Yes Norma, drained Percent of map unit: 5 percent Landform: Depressions Other vegetative classification: Seasonally Wet Soils (G002XN202WA) Hydric soil rating: Yes Terric medisaprists, undrained Percent of map unit: 5 percent Landform: Depressions Other vegetative classification: Wet Soils (G002XN102WA) Hydric soil rating: Yes 57—Ragnar fine sandy loam, 0 to 8 percent slopes Map Unit Setting National map unit symbol: 2hzk Elevation: 300 to 1,000 feet Mean annual precipitation: 35 to 65 inches Mean annual air temperature: 50 to 54 degrees F Frost-free period: 150 to 210 days Farmland classification: All areas are prime farmland Map Unit Composition Ragnar and similar soils: 100 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Ragnar Setting Landform: Outwash plains Parent material: Glacial outwash Typical profile H1 - 0 to 2 inches: ashy fine sandy loam H2- 2 to 24 inches: ashy sandy loam H3- 24 to 60 inches: loamy sand Properties and qualities Slope: 0 to 8 percent Depth to restrictive feature: 20 to 40 inches to strongly contrasting textural stratification Natural drainage class: Well drained 17 Custom Soil Resource Report Capacity of the most limiting layer to transmit water(Ksat): High (1.98 to 5.95 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low(about 3.4 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2e Hydrologic Soil Group: A Other vegetative classification: Droughty Soils (G002XN402WA) Hydric soil rating: No 18 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nres.usda.gov/wps/portal/ nres/detail/national/soils/?cid=nres 142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nres.usda.gov/wps/portal/nres/detail/national/soils/?cid=nres142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nres.usda.gov/wps/portal/nres/detail/national/soils/?cid=nresl42p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nres.usda.gov/wps/portal/nres/detail/soils/ home/?cid=nres142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nres.usda.gov/wps/portal/nres/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 19 Custom Soil Resource Report United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nres.usda.gov/wps/portal/ nres/detail/soils/scientists/?cid=nres142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nres.usda.gov/wps/portal/nres/detail/national/soils/? cid=nres142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/lnternet/FSE—DOCUMENTS/nrcsl 42p2_052290.pdf 20 Drainage Report—East Arlington Substation Order#100002342 APPENDIX 6 Department of Ecology Fact Sheet#95-157-TCP—Mineral Insulating Oil Cleanup Standard Page 17 A A S N I N O T O N STATE IVllneral Insulating Oil Cleanup Standard Ae�ATET�a 0 L 0 Y Recommended Approach to the Cleanup of Mineral Insulating Oil Contaminated Sites Based on the unique characteristics of mineral ownership of the Washington electric utility industry insulating oil and of substation and distribution or Bonneville Power Administration,where stations,Ecology is recommending that cleanup institutional controls are in place,given the industrial actions be conducted for historical releases of setting.If property is transferred for uses other than non-PCB mineral insulating oil(ASTM D-3487)at industrial utility use,residential standards may apply. sites where contamination levels exceed 2000 mg/kg The historical contamination should be addressed in (ppm)• accordance with the intended land use. Ecology does not recommend the completion of These types of sites include high-voltage substation or risk-based evaluations at Washington electric utility distribution stations or switchyards as defined by the substations and distribution stations due to the unique Bonneville Power Administration Definitions, site characteristics of these facilities and the low DOE/BP-2279,April 1994.Pad-and pole-mounted toxicity and environmental behavior of.mineral electrical transformers are not considered in this fact insulating oil.Mineral insulating oil is acknowledged sheet.The Toxics Cleanup Program,Department of as very different in its physical/chemical nature as Ecology,will consider additional data as it becomes compared to other petroleum hydrocarbon products. available.High-voltage substations or distribution For current and historical mineral insulating oil spills stations and switchyards are carefully controlled, that are small and well defined,electric utility fenced areas with special working surface areas resources should be dedicated to the cleanup of the site (crushed gravel,compacted soils and clays)to eliminate and not to extensive risk-based evaluations.Historical static electricity or electrical arcs. mineral insulating oil spills refers to those spills that have remained beneath heavy transformers in Chemical characteristics of mineral insulating oiL high-voltage substation or distribution stations and Mineral insulating oil used in electrical equipment is a switchyards for longer than six months. highly refined petroleum distillate. Mineral insulating oil is used as an insulating and cooling medium in Technical Utility Industry Issues electrical equipment. Physical/chemical properties of mineral oil are strictly controlled by federal regulation Electric utility site characteristics. Electric utility and product specifications. Synonyms for mineral sites where mineral insulating oil is used are unique insulating oil include mineral oil,liquid petroleum, because of the standards associated with the generation liquid paraffin,paraffin oil,medicinal oil and medicinal and storage of energy,electric voltage loads,and white oil,white oil and white mineral oil,good grade oil transmission of electric energy.The utility industry and good grade white oil,and technical white oil. also maintains unique requirements for safety,land use,and environmental resource protection.For sites Biological Effects and Environmental Issues where historical release residues remaining onsite exceed the 2000 mg/kg(ppm),monitoring shall be ASTMD-3487 Toxicity. Mineral insulating oil poses conducted as an institutional control.Future land use a low potential for toxicity,and is similar to mineral must also remain in an industrial setting and within the r (Over) If you have special accommodation needs,please call(360)407-6300(voice)or(360)407-6306(TDD); amonamn Ecology is an Equal Opportunity and Affirmative Action employer. Fact Sheet#95-157-TCP a printed on recycled paper oil used for food packaging and processing(21 CFR 178.3620). Known information from acute,subchronic and chronic toxicity tests shows little evidence of adverse health effects. Animal toxicity tests using mineral oils shows no evidence of carcinogenicity,nor adverse reproductive or developmental effects. Mineral insulating oil is similar to mineral oil used for cosmetics and pharmaceuticals(USP XXII,CTFA),in that it is non-irritating to the skin and eyes,is non-sensitizing and non-allergenic,and exhibits minimal systemic toxicity via multiple routes of exposure.The 2000 mg/kg(ppm) cleanup level for mineral insulating oil was selected because of low acute(LDSo >5000 mg/kg),subchronic(no observed effect level> 1500-4350 mg/kg-day)and chronic toxicities (no observed effect level> 1200-6000 mg/kg-day)using different animal species and routes of exposure.There is no data showing mineral oil to be mobile or to present a threat to groundwater at soil concentrations at less than 2000 mg/kg. Behavior in the environment. Based on the physical/chemical properties of mineral insulating oil,the threat of cross-media contamination of groundwater from release of mineral insulating oil from electrical equipment is minimal.Mineral insulating oil(ASTM D-3487)is non-volatile,insoluble(hydrophobic),and highly adsorbs to organic particles in soil. Conclusion and Recommendation. Ecology recommends a clear distinction in the Model Toxics Control Act (MICA)cleanup standards between electric utility mineral insulating oil and other types of petroleum hydrocarbons. Design characteristics of electric substations or distribution stations preclude direct human exposure and environmental releases of historic mineral insulating oil. Cleanup standards for(non-PCB contaminated)electric utility industry mineral insulating f oil must acknowledge the difference in mineral insulating oil chemical composition,toxicity,and behavior in the environment. i i ' I i Drainage Report—East Arlington Substation Order#100002342 APPENDIX C WWHM3 Project Report, Impervious Surface Area Table, and Stage Storage-Discharge Table Page 18 WWHM2012 PROJECT REPORT Project Name: East Arlington tdh 2-14-18 Site Name: East Arlington Substation Site Address: 21210 87th Ave NE City : Arlington Report Date: 2/14/2018 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1 .20 Version Date: 2017/04/14 Version : 4 .2 .13 ------------------- Low Flow Threshold for POC 1 : 50 Percent of the 2 Year High Flow Threshold for POC 1: 50 year PREDEVELOPED LAND USE Name : EXST CONDITIONS Bypass: No GroundWater: No Pervious Land Use acre A B. Lawn, Flat .058 A B IMP INF FLAT .896 Pervious Total 0. 954 Impervious Land Use acre PARKING FLAT 0.2959 Impervious Total 0.2959 Basin Total 1.2499 Element Flows To: Surface Interflow Groundwater MITIGATED LAND USE Name : DEV YARD Bypass: No Groundwater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre PARKING FLAT 1.0901 Impervious Total 1.0901 Basin Total 1.0901 Element Flows To: Surface Interflow Groundwater SUBSTATION YARD Name DEV FRONTAGE Bypass: Yes GroundWater: No Pervious Land Use acre A B, Lawn, Flat .1176 Pervious Total 0.1176 Impervious Land Use acre DRIVEWAYS FLAT 0.0422 Impervious Total 0.0422 Basin Total 0.1598 Element Flows To: Surface Interflow Groundwater Name SUBSTATION YARD Bottom Length: 200.00 ft. Bottom Width: 224 . 63 ft. Trench bottom slope 1: 0 To 1 Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer: 1. 17 Pour Space of material for first layer: 0.4 Material thickness of second layer: 0.33 Pour Space of material for second layer: 0 .4 Material thickness of third layer: 0 Pour Space of material for third layer: 0 Infiltration On Infiltration rate: 1 . 63 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft. ) : 210. 985 Total Volume Through Riser (ac-ft. ) : 0 Total Volume Through Facility (ac-ft.) : 210. 985 Percent Infiltrated: 100 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 0.08333 ft. Riser Diameter: 6 in. Element Flows To: Outlet 1 Outlet 2 Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 1.031 0.000 0.000 0.000 0.0130 1.031 0.005 0.000 1. 695 0.0260 1.031 0.010 0.000 1.695 0.0390 1.031 0.016 0.000 1.695 0.0520 1.031 0.021 0.000 1.695 0.0650 1.031 0.026 0.000 1.695 0.0780 1.031 0.032 0.000 1.695 0.0910 1.031 0.037 0.003 1.695 0.1040 1.031 0.042 0.015 1.695 0.1170 1.031 0.048 0.032 1.695 0.1300 1.031 0.053 0.053 1.695 0.1430 1.031 0.059 0.076 1.695 0.1560 1.031 0.064 0.102 1.695 0.1690 1.031 0.069 0.129 1.695 0.1820 1.031 0.075 0.157 1.695 0.1950 1.031 0.080 0.186 1.695 0.2080 1.031 0.085 0.214 1.695 0.2210 1.031 0.091 0.242 1.695 0.2340 1.031 0.096 0.268 1.695 0.2470 1.031 0.101 0.292 1.695 0.2600 1.031 0.107 0.314 1.695 0.2730 1.031 0.112 0.333 1.695 0.2860 1.031 0.118 0.349 1.695 0.2990 1.031 0.123 0.363 1.695 0.3120 1.031 0.128 0.374 1.695 0.3250 1.031 0.134 0.383 1.695 0.3380 1.031 0.139 0.397 1.695 0.3510 1.031 0.144 0.407 1.695 0.3640 1.031 0.150 0.417 1.695 0.3770 1.031 0.155 0.426 1.695 0.3900 1.031 0.160 0.436 1.695 0.4030 1.031 0.166 0.445 1.695 0.4160 1.031 0.171 0.454 1.695 0.4290 1.031 0.177 0.462 1.695 0.4420 1.031 0.182 0.471 1.695 0.4550 1.031 0.187 0.480 1.695 0.4680 1.031 0.193 0.488 1.695 0.4810 1.031 0.198 0.496 1.695 0.4940 1.031 0.203 0.504 1.695 0.5070 1.031 0.209 0.512 1. 695 0.5200 1.031 0.214 0.520 1.695 0.5330 1.031 0.219 0.528 1.695 0.5460 1.031 0.225 0.535 1.695 0.5590 1.031 0.230 0.543 1.695 0.5720 1.031 0.236 0.550 1.695 0.5850 1.031 0.241 0.557 1.695 0.5980 1.031 0.246 0.564 1.695 0. 6110 1.031 0.252 0.572 1.695 0. 6240 1.031 0.257 0.579 1.695 0. 6370 1.031 0.262 0.585 1.695 0. 6500 1.031 0.268 0.592 1.695 0. 6630 1.031 0.273 0.599 1.695 0. 6760 1.031 0.278 0.606 1.695 0. 6890 1.031 0.284 0.612 1.695 0.7020 1.031 0.289 0.619 1.695 0.7150 1.031 0.295 0.625 1.695 0.7280 1.031 0.300 0.632 1.695 0.7410 1.031 0.305 0.638 1.695 0.7540 1.031 0.311 0.644 1.695 0.7670 1.031 0.316 0.651 1.695 0.7800 1.031 0.321 0.657 1.695 0.7930 1.031 0.327 0.663 1.695 0.8060 1.031 0.332 0.669 1.695 0.8190 1.031 0.337 0.675 1.695 0.8320 1.031 0.343 0.681 1.695 0.8450 1.031 0.348 0.687 1.695 0.8580 1.031 0.354 0.693 1.695 0.8710 1.031 0.359 0.698 1.695 0.8840 1.031 0.364 0.704 1. 695 0.8970 1.031 0.370 0.710 1.695 0. 9100 1.031 0.375 0.715 1.695 0. 9230 1.031 0.380 0.721 1.695 0. 9360 1.031 0.386 0.727 1.695 0. 9490 1.031 0.391 0.732 1.695 0. 9620 1.031 0.396 0.738 1.695 0. 9750 1.031 0.402 0.743 1.695 0. 9880 1.031 0.407 0.748 1.695 1.0010 1.031 0.413 0.754 1.695 1.0140 1.031 0.418 0.759 1.695 1.0270 1.031 0.423 0.764 1.695 1.0400 1.031 0.429 0.770 1.695 1.0530 1.031 0.434 0.775 1.695 1.0660 1.031 0.439 0.780 1.695 1.0790 1.031 0.445 0.785 1.695 1.0920 1.031 0.450 0.790 1.695 1.1050 1.031 0.455 0.795 1.695 1.1180 1.031 0.461 0.800 1.695 1.1310 1.031 0.466 0.806 1.695 1.1440 1.031 0.471 0.810 1.695 1.1570 1.031 0 .477 0.815 1. 695 1.1700 1.031 0 .482 0.820 1. 695 ANALYSIS RESULTS Stream Protection Duration Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.954 Total Impervious Area:0.2959 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.1176 Total Impervious Area:1.1323 Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0 .181129 5 year 0 .262966 10 year 0 .324827 25 year 0 .41212 50 year 0.484042 100 year 0.562099 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 .025323 5 year 0 .036322 10 year 0 .04456 25 year 0 .0561 50 year 0.065548 100 year 0.07575 Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.169 0.024 1950 0.251 0.034 1951 0.195 0.028 1952 0.164 0.023 1953 0.191 0.027 1954 0.468 0.062 1955 0.325 0.043 1956 0.093 0.013 1957 0.233 0.031 1958 0.365 0.052 1959 0.150 0.021 1960 0.150 0.021 1961 0.498 0.070 1962 0.180 0.026 1963 0.309 0.042 1964 0.170 0.023 1965 0.138 0.020 1966 0.138 0.020 1967 0.307 0.044 1968 0.162 0.023 1969 0.350 0.049 1970 0.125 0.018 1971 0.217 0.029 1972 0.222 0.032 1973 0.183 0.026 1974 0.255 0.034 1975 0.183 0.026 1976 0.122 0.017 1977 0.124 0.018 1978 0.100 0.014 1979 0.398 0.053 1980 0.141 0.020 1981 0.130 0.018 1982 0.127 0.018 1983 0.188 0.025 1984 0.154 0.022 1985 0.232 0.031 1986 0.315 0.043 1987 0.182 0.026 1988 0.149 0.021 1989 0.216 0.029 1990 0.119 0.017 1991 0.151 0.022 1992 0.156 0.022 1993 0.114 0.016 1994 0.133 0.019 1995 0.112 0.016 1996 0.252 0.034 1997 0.404 0.053 1998 0.202 0.029 1999 0.106 0.015 2000 0.328 0.047 2001 0.110 0.016 2002 0.107 0.015 2003 0.146 0.021 2004 0.277 0.039 2005 0.128 0.018 2006 0.328 0.043 2007 0.264 0.036 2008 0.134 0.019 2009 0.129 0.018 Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.4977 0.0701 2 0.4684 0.0624 3 0.4039 0.0531 4 0.3985 0.0528 5 0.3650 0.0519 6 0.3498 0.0492 7 0.3281 0.0468 8 0.3280 0.0437 9 0.3252 0.0434 10 0.3148 0.0433 11 0.3089 0.0427 12 0.3067 0.0419 13 0.2768 0.0395 14 0.2642 0.0356 15 0.2545 0.0345 16 0.2515 0.0345 17 0.2513 0.0336 18 0.2330 0.0317 19 0.2317 0.0314 20 0.2224 0.0312 21 0.2170 0.0295 22 0.2158 0.0293 23 0.2016 0.0287 24 0.1953 0.0279 25 0.1909 0.0272 26 0.1880 0.0260 27 0.1834 0.0260 28 0.1825 0.0260 29 0.1823 0.0257 30 0.1804 0.0251 31 0.1702 0.0241 32 0.1687 0.0231 33 0.1644 0.0231 34 0.1621 0.0228 35 0.1563 0.0221 36 0.1538 0.0219 37 0.1513 0.0216 38 0.1504 0.0213 39 0.1502 0.0213 40 0.1491 0.0210 41 0.1464 0.0209 42 0.1410 0.0197 43 0.1379 0.0196 44 0.1376 0.0196 45 0.1338 0.0190 46 0.1329 0.0187 47 0.1298 0.0183 48 0.1286 0.0182 49 0.1279 0.0182 50 0.1273 0.0178 51 0.1250 0.0178 52 0.1240 0.0177 53 0.1217 0.0173 54 0.1190 0.0170 55 0.1140 0.0163 56 0.1122 0.0160 57 0.1100 0.0157 58 0.1068 0.0152 59 0.1056 0.0147 60 0.1001 0.0141 61 0.0930 0.0129 Stream Protection Duration POC #1 The Facility PASSED The Facility Flow(cfs) Predev Mit Percentage Pass/Fail 0.0906 841 0 0 Pass 0.0945 731 0 0 Pass 0.0985 637 0 0 Pass 0.1025 564 0 0 Pass 0.1065 492 0 0 Pass 0.1104 445 0 0 Pass 0.1144 407 0 0 Pass 0.1184 365 0 0 Pass 0.1224 324 0 0 Pass 0.1263 289 0 0 Pass 0.1303 265 0 0 Pass 0.1343 242 0 0 Pass 0.1383 222 0 0 Pass 0.1422 202 0 0 Pass 0.1462 189 0 0 Pass 0.1502 167 0 0 Pass 0.1542 148 0 0 Pass 0.1581 139 0 0 Pass 0.1621 127 0 0 Pass 0.1661 120 0 0 Pass 0.1701 111 0 0 Pass 0.1740 105 0 0 Pass 0.1780 101 0 0 Pass 0.1820 96 0 0 Pass 0.1860 90 0 0 Pass 0.1899 82 0 0 Pass 0.1939 78 0 0 Pass 0.1979 71 0 0 Pass 0.2019 66 0 0 Pass 0.2058 63 0 0 Pass 0.2098 58 0 0 Pass 0.2138 54 0 0 Pass 0.2177 49 0 0 Pass 0.2217 43 0 0 Pass 0.2257 40 0 0 Pass 0.2297 38 0 0 Pass 0.2336 36 0 0 Pass 0.2376 36 0 0 Pass 0.2416 35 0 0 Pass 0.2456 34 0 0 Pass 0.2495 32 0 0 Pass 0.2535 29 0 0 Pass 0.2575 27 0 0 Pass 0.2615 27 0 0 Pass 0.2654 26 0 0 Pass 0.2694 24 0 0 Pass 0.2734 23 0 0 Pass 0.2774 22 0 0 Pass 0.2813 22 0 0 Pass 0.2853 20 0 0 Pass 0.2893 20 0 0 Pass 0.2933 20 0 0 Pass 0.2972 18 0 0 Pass 0.3012 17 0 0 Pass 0.3052 16 0 0 Pass 0.3092 14 0 0 Pass 0.3131 14 0 0 Pass 0.3171 12 0 0 Pass 0.3211 11 0 0 Pass 0.3251 11 0 0 Pass 0.3290 8 0 0 Pass 0.3330 8 0 0 Pass 0.3370 8 0 0 Pass 0.3410 8 0 0 Pass 0.3449 7 0 0 Pass 0.3489 7 0 0 Pass 0.3529 6 0 0 Pass 0.3569 6 0 0 Pass 0.3608 6 0 0 Pass 0.3648 6 0 0 Pass 0.3688 5 0 0 Pass 0.3728 5 0 0 Pass 0.3767 5 0 0 Pass 0.3807 5 0 0 Pass 0.3847 5 0 0 Pass 0.3887 5 0 0 Pass 0.3926 5 0 0 Pass 0.3966 5 0 0 Pass 0.4006 4 0 0 Pass 0.4046 3 0 0 Pass 0.4085 2 0 0 Pass 0.4125 2 0 0 Pass 0.4165 2 0 0 Pass 0.4204 2 0 0 Pass 0.4244 2 0 0 Pass 0.4284 2 0 0 Pass 0.4324 2 0 0 Pass 0.4363 2 0 0 Pass 0.4403 2 0 0 Pass 0.4443 2 0 0 Pass 0.4483 2 0 0 Pass 0.4522 2 0 0 Pass 0.4562 2 0 0 Pass 0.4602 2 0 0 Pass 0.4642 2 0 0 Pass 0.4681 2 0 0 Pass 0.4721 1 0 0 Pass 0.4761 1 0 0 Pass 0.4801 1 0 0 Pass 0.4840 1 0 0 Pass Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. LID Report LID Technique Used for Total Volumn Volumn Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volumn Volumn Volumn Water Quality Treatment Facility (ac-ft.) Infiltration Infiltrated Treated (ac-ft) (ac-ft) Credit SUBSTATION YARD POC N 192.20 N 99.90 Total Volume Infiltrated 192.20 0.00 0.00 99.90 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed Perind and Impind Changes No changes have been made. This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright Q by : Clear Creek Solutions, Inc. 2005-2018; All Rights Reserved. CONSTRUCTION PERMIT APPLICATION Coniu►tlnity&Economic Development City of Arlington • 18204 59t1i Avenue NE • Arlington,WA 98223 • Phone(360)403-3551 CIVIL(TYPE I) 13 GRADING/PAVING/DRAINAGE(TYPE II) a RIGHT OF WAY(TYPE III) TYPE 1&11 ONLY NEW DEVELOPMENT REDEVELOPMENT Project Name: East Arlington Switching Station Site Construction Snohomish County Tax Parcel I.D.#: 31051200200500 Project Address/Location: 21210 87th Ave NE, Arlington, WA 98223 Description of Project:Demolition of existing substation/switchyard adn construction of a 6 breaker ring bus OWNER Name: Public Utility District No. 1 of SnohomishCounty Address: PO Box 1107 City:Everett State:WA Zi :98206-1107 Pliolle: 425-783-1000 Email: APPLICANT Narue: Tom Hendricks Address: PO Box 1107, Mail Stop 01 city: Everett State:WA Zi 98206-1107 pllolle:425-783-5022 Entail: whendricks@snopu .com ENGINEER Name: Tom Hendricks Address:PO Box 1107, Mail Stop 01 city: Everett State:WA Zi :98206-1107 Pl►orte:425-783-5022 Email:tdhendricks@snopud.com License #:43183 Expiration:09/09/2019 CONTRACTOR Name: To Be Determined Address: City: State: Zip: Phone: Email: License#: Expiration: I, hereby certify that I have read and examined this application,City of Arlington Municipal Code,Standard Plan& Specifications. Peitonuance of the proposed work shall follow all applicable laws and regulations.The owner/applicant shall assume full and complete responsibility for said work and shall be responsible for[lie acquisition and compliance of all applicable penuils and/or authorizations which may include, but not limited to, Right of Way Penult,WSDW llydraulic Project A proval lIPA),WSDOR Notice of Intent(NOI),National Pollutant Discharge lilimination System(NPD13S),Anuy Corp.of Engineers Permits re to men of the ndangered Species Act,and the Forest Practices Application(FPA). Signature /)t�r►� Piint Name: I ovtn 4 Ern r GK S Date:_ 611 9/Z o l e Pagel of 2 RLiV 10/2017 Complete package constitutes all,items. Only„complete„Sri hinittals will be accepted Civil-Submittal Requirements,Tyne I: ❑ Complete Application; O Construction Puns including cut/fill quantities; ■ 2 hill size plan sets 22"x 34" • PDF file of the complete plan set ■ 1 hill size set of landscape plans 22"x 34" ❑ Marysville Utility plans if applicable(2 sets); ❑ Drainage Analysis including calcuations and downstream analysis(2 sets)and(PDF file);refer to Stormwater Drainage Requirements; ❑ Geotechnical Report(2 sets) and(PDF file); ❑ SEPA is required if 500 or more cubic yards of cut/fill is proposes{(not required if included with a Land Use Permit); ❑ Grading cut/fill quantity: , O Drafts of easement(s)dedication(s),and/orCAPE(s)for review; ❑ FIood Hazard Penuit Application and required documentation if project is within 100 year flood plain;refer to Flood Hazard guidance documents; ❑ Constnction Caletdation Worksheet; ❑ NPDES Permit(if required);See Storm Water Drainage Report,New or RedevelopmentRloweharts; O Assurance Device will be requires)prior to Permit Issuance(Bond orAssignment of Funds); ❑ Plan Check Fee clue at time of pennit submittal. .rading�Paving.1 Drainage Submittal,Requirements.T)ne Il: 1 RI Complete Application; F1 Construction Plans including huport/export quantities; ■ 2 fidl size plan sets 22"x 34" I ■ PDF file of the complete plan set Drainage Analysis including calculations and downstream analysis(2 sets)and(PDF file);refer to Stormwater Drainage Requirements; Geotechnical Report(2 sets)and(PDF file); SEPA is required if 500 or more cubic yarns of cut/fill is proposed(not required if included with a Land Use Penuit); 0 Grading cut/fill quantity:2500 CY/2500 CY ; Construction Calcidation Woricsheet; P1 NPDES Permit(if required);See Storm Water Drainage Report,New or RedevelopmentRlowcharts; Plan Clreck Fee due at time of pennit submittal. Right of Way Submittal Requirements,Tyre III: ❑ Complete Application; ❑ Construction Plans; ❑ Traffic Control Plan; O Road Closure Request; ❑ Temporary Erosion&Sediment Control(TESL)Plan; ❑ Certificate of Insurance with the City of Arlington named as Additional Insured; ❑ Assurance Device will be required prior to Permit Issuance (Bond or Assignment of Funds); ❑ Engineers Estimated Cost of Construction;$ ❑ Permit fee slue at time of permit issuance. I Page 2 of RRrV 10/2017 EAST ARLINGTON SWITCHING STA- - I---- ION SITE CONSTRUCTION PUBLIC WORKS CONTRACT PUBLIC UTILITY DISTRICT No 1 OF SNOHOMISH COUNTY EVERETT, WASHINGTON N aw z DRAWING INDEX: DRAWING NUMBER DESCRIPTION S-4-T2 TITLE SHEET FOR SITE CONSTRUCTION S-4-81 LEGENDS vI S-4-82 ABBREVIATIONS m c� S-4-DI SITE DEMOLITION PLAN z it S-4-D2 CONDUIT DEMOLITION PLAN S-4-D3 GROUNDING DEwOLITION PLAN ,� ��rnyy99 S-4-D4 EXISTING FOUNDATION DETAILS i THRU 9 ITT,yY..�.-f UN E i =.a S-4-D5 EXISTING FOUPNDA7iON DETAILS 10,11 & 18 S-4-D6 EXISTING FOUNDATION DETAILS 12 THRU 16 NQp i \_ i S-4-D7 EXISTING FOUNDATION DETAIL 17 Zvp _ 1 A S-4-D8 EXISTING FOUNDATION DETAILS 19,20 & 22 y pm S-4-D9 EXISTING FOUNDATION DETAIL 21 P S-4-D10 EXISTING FOUNDATION DETAIL 22 p S-4-DI1 EXISTING FOUNDATION DETAILS 23.24 & 25 t S-4-D12 EXISTING FENCE FOUNDATIONS & CURBING,GATE SILLS & STOPS, ! LIGHTING POSTS & FOOTINGS o t r ARLEPNCTON S-4-D13 EXISTING CABLE TRENCH SYSTEM DETAILS AND OIL SEPARATOR BASIN DETAIL \I { S-4-C1 SITE PLAN y f! d 2041y T zaF $J i � 5-4-02 RECORD OF SURVEY @ S-4-03A 2016 TOPOGRAPHIC SURVEY SHEET 1 OF 2 r S-4-CM 2016 TOPOGRAPHIC SURVEY SHEET 2 OF 2 3133 PROJECT SITE S-4-C4 STORMWATER POLLUTION PREVENTION PLAN (SWPPP) r° L uvprov 21210 87TH AVE NE S-4-05 GRADING AND DRAINAGE PLAN suspst 9 ARLIN'CTON,WA 98223 S-4-C6 GRADING AND DRAINAGE DETAILS AND SECTIONS SNOHOMISH COUNTY 1 S-4-C8 DRIVEWAY PLANS AND SECTIONS �c 1�� S-4-09 FENCE PLAN �1 S-4-00 FENNC£ DETAILS Fl.E:.Fr U16RY DNSFR of P)1 VICINITY MAP S-4-Cll FEWKE DETAILS ORDER 100002342 NW 1/4,SEC 12,TWP 31,Y,RGE 5E,WM _ S-4-C12 IDENTIFICATION SIGN DETAILS MD ELEVATION OPERATION? S-4-C13 FOUNDATION PLAN S-4-014 DRILLED PIER AND SPREAD FOOTING FOUNDATIONS SCALE NONE i S-4-C15 FOUR PEDESTAL. SPREAD FOOTING FOINNNDATIONS DFTR DPA S-4-CI6 CIRCUIT BREAKER SLABS S-4-017 COHTROI. ENCLOSURE SLABS CHKR ()mH S-4-C18 CONDUIT PLAN ENGR S-4-C19 CONDUIT SCHEDULE AND MATERIAL LIST FOR 2018 SITE CONSTRUCTION APVD �tV4 S-4-C20 COPNIQUIT At* VAULT DETAILS AND SECTIONS S-4-C21 CONDUIT TRENCH SECTIONS AND DETAILS DATE SNK I S-4-C22 GROUNDING PLAN EAST i S-4-C23 GROUNDING DETAILS ARLINGTON S-4-024 GROUNDING DETAILS & GROUNDING MATERIAL LIST SWITCHING STATION TITLE SHEET LEGEND CONSTRUCTION X S-4-XX DRAWINGS PROVIDED FOR REFERENCE ONLY CALL 48 HOURS S^ BEFORE YOU DIIG] 1-800-424-5555s REV DRAWING —T2 0 i S-4 4a f SITE/SURVEY UTILITY ELECTRICAL ONE LINE EXISTING PROPOSED DESCRIPTION EXISTING PROPOSED DESCRIPTION SYMBOL DESCRIPTION ----- ---- PROPERTY LINE 12" CUP f2"CNP —� DISCONNECT SWITCH,TYPE "A" RIGHT-OF-WAY LINE `-------- CULVERT ARC RESTRICTOR SWITCH,TYPE "B" -------- EASEMENT LINE _i0"SD— —10"SD— STORM DRAIN PIPE & SIZE LOOP OR PARALLEL BREAK SWITCH,TYPE "C" Q PROPERTY CORNER ---10"SD---- ---10"SD---- P R ORAiED STORM DRAIN �' LOAD BLEAK DISCONNECT SWITCH,TYPE "D" TEMPORARY BENCH )HARK PIPE & GROUNDING SWITCH --G--- -------G— GAS -" "- FENCE SUBSTATION SECURITY FENCE —6" S— —8"S---- SANITARY SEWER LINE & SIZE CS CIRCUIT SWITCHER -a 0— SUBSTATION SECURITY FENCE —`"T— --T— TELEPHONE SILT FENCE —TV------ '--"'TV— OVERHEAD CABLE TELEVISION FUSE (LOW VOLTAGE) -x x- HIGH VISIBILITY FENCE -----2"W— —2°W` WATER LINE & SIZE FUSED DISCONNECT SWITCH ----� -�« SURFACE FLOW -{}- -f- CATCH BASIN FUSE (POWER) — — EDGE OF WETLAND/STREAM SC SUPERVISORY CONTROL CH/ �Co —•CO CLEANOUT �f2A CURRENT TRANSFORMER —� - �^•••^ CONTOUR LINE CEIITERLIN£ � �_ MANHOLE ^�PA CURRENT TRANSFORMER,BUSHING TYPE 66---------- —68— CONTOUR EENE - - --- -- ------- GRADE BREAK v Y FIRE HYDRANT -- �I� GROUND E TOC TOC TOP OF CURB/CONCRETE ® 9 WATER METER "" " ` NEUTRAL REACTOR (O0'OO ELEVATION �� '�E� SURGE ARRESTER z ) ❑ Q TELEPHONE JUA'CTION BOX t a �i�t��-- BATTERY 4 o- �00^.00 SPOT ELEVATION) 0 • POWER DISTRIBUTION POLE VOLTAGE TRANSFORMER POTENTIAL '� w 100.00) TRANSFORMER OR SERVICE TRANSFORMER ter- �rr�-rrr- -�r-�r-m� EOCE OF PAVEMENT ® ® POWER TRANSMISSION POLE La LANDSCAPED AREA -P -P` OVERHEAD POWER f-<j y-rn 3-WINDING POWER TRANSFORMER WITH LTC O O EVERGREEN SHRUB -"- UNDERGROUND POWER/CONDUIT Q (D TREE (DECIDUOUS) E- E•-'• GUY WIRE AND ANCHOR = TREE (CONIFER) Vl Vi ELECTRICAL VAULT 12-) CIRCUIT BREAKER y 5 � MA[LBOx 12-xx m � > DRAWOUT CIRCUIT BREAKER a ( O W WARNING SIGN ELECTRICAL. GROUNDING (DANGER HIGH VOLTAGE) C] TERMINAL BLOCK POINT m EMBANKMENT EXISTING PROPOSE D DESCRIPTION 0 WIRE PULL TERMINAL BLOCK POINT ------- GROUNDING CONDUCTOR IN SHORTING TERMINAL BLOCK POINT 5v ELECTRICAL DEVICES Q WIRE NUMBER CHANCE TERMINAL BLOCK POINT �H --- --- PARALLEL CONNECTION zo DEVICE N0. DESCRIPTION ® W&IROECKp PO NF E WIRE PLRL TERMINAL Uo 00 $ PARALLEL WIRE TAIL WITH � � WERE NUMBER CHANCE SHORTING TERMINAL ao 11 MULTI-FUNCTION RELAY t GROUND L IRE TAIL WITH ❑ 16 DATA NETWORK/COM(1(UNICATION DEVICES ' BLOCK POINT __- CROSS CONNECTION i ¢--- 21 DISTANCE IMPEDANCE RELAY E3 ISOLATION TYPE TERMINAL BLOCK/POINT o 26T OIL TEMPERATURE TRANSFORMER (E.G.ALLEN BRADLEY 1492-WKDS) 27 IM1�DER VOLTAGE RELAY GROLkNDING PLATFORM 49T WINDING TEMPERATURE RELAY TRANSFORMER VOL AGE REGULATOR £ SON/SY( NEUTRAL INSTANTANEOUS AND OVERCURRENT RELAY GROUND ROD 50/51 PHASE INSTANTANEOUS AND OVERCURRENT RELAY � �} GROUND WELL OO MOTOR OPERATOR o i 50BF BREAKER FAILURE RELAY i 52 POWER CIRCUIT BREAKER 63 PRESSURE SENSITIVE RELAY TEXT SYMBOLS INDICATING LIGHT 71T OIL LEVEL TRANSFORMER 79 RECLOSING RELAY HIGH VOLTAGE TERMINATION BETWEEN AN ' c R B1 UNDERFREQLEtiCY RELAY YS k$OL MEANING *- EXPOSED CONDUCTOR TO INSULATED p1 H $3 PROCESS CONTROLLER DEGREE CONDUCTOR OR BUSHING 85 CARRIER CONTROLLED RELAY ± PLUS OR MINUS -}--- ELECTRICAL NODE,COMMON CONNECTION 86 LOCKOUT RELAY (y OHMS 868 BUS LOCKOUT RELAY ------- UNDERGROUND PULL WIRE 86T TRANSFORMER LOCKOUT RELAY L ANG(.E y 87B BUS DIFFERENTIAL RELAY PHASE.DIAMETER —{(-3 COUPLING CAPACITOR VOLTAGE TRANSFORMER I SNOHOMISH COUNTY 87i TRANSFORMER DIFFERENTIAL RELAY CENTER LINE 89 LANE SWITCH Nl@fC uNlfrf t#STR€CT NO N 97 LOGIC OR DATA PROCESSOR PROPERTY LINE 0 DATA POINT __X AUXILIARY RELAY FEET.MINUTES ,o ORDER K)0002342 INCHES,SECONDS 1 MOLDED CASE BREAKER } & AND �o OPERATION DRAFTING SCALE NONE SYMBOL DESCRIPTION SECTION ELEVATION DFTR OPA - --- CENTER LINE ��A ��'SECTION ELEVATION, ;x OR PROFILE LETTER OR PROFILE LETTER DETAIL NUMBER OR DETAIL NUMBER CHKR DM CONDUIT SIZE 012 DWG NUMBER WHERE C12 DWG NUMBER6-IF LEFT BtJNX INDICATES SECTION ELEVATION, WHERE DETAIL SECTION.ELEVATION PROFILE ENGR OORRIJ,\R41LE CAN BE CAN BE FOUND OR DEW IS SH AA ON CONNDUIT IDENTIFICATION NUMBER THE SAME DRAWIIM' APVD 3"D 127 MATERIAL ITEM DESIGNATION , GATE SECTION ELEVATION 115VSt STEEL STRUCTURE DESIGNATION( SECTION ELEVATION, OR PRON`1LE LETTER ECTIO OR PROFILE LETTER I DETAIL NUMBER OR DETAIL NUMBER EAST (21 OR AO CONSTRUCTION/DEVELOPMENT NOTE �`a" 0' C� DWG NUMBER WHERE Vz"= i'-O" Cl DWG NUMBER IF LEFT 8LR5K I=ATES ARLINGTON SECTION,ELEVATION WHERE DETAIL SECTION ELEVATION PROFILE SWITCHING OR PROFILE IS TA KtN IS TAKEN OR DETAIL 1S SHO»'�i on N=S BASELLN�PROJECT REFERENCE LINE THE SAVE DRAWN10 STATION SCALE SCALE TATI TATI LEGENDS S 00.39 5'i`E —_:'7 BEARING OF REFERENCE LINE s IT 35783"' IS SITE COORDINATE - E 1305863,041 FUSE LETTERS TO DESIGNATE SECTIONS, NOTE. REV DRAWING �€ ELEVATIONS,OR PROFILES. -----0 OR------0 COLWV/PIER GRID LINE "USE NUMBERS TO DESIGNATE DETAILS. BE NOTE�D1 ON IWIROM VI�)AL DRAAWIINGS.ILL 0 S-AF-Bl 1� � 3 7 TEXT TERM TEXT TERM TEXT TERM TEXT TERM TEXT TEfua A AMPERE DL DAYLIGHT KWHR KILOWATT HOUR RC REINFORCED CONCRETE VLT VAULT AS ANCHOR BOLT OT DRAIN TILE L LEFT,LENGTH OF ARC RD ROAD,ROUND VM VOLTMETER ABANO ABANDONED DW DRIVEWAY LB LOADBREAK,POUNDS REC RECORDING W WEST,WATER LINE AC ALTERNATING CURRENT DWG DRAWING L8FT POUND FOOT RECL RECLOSER W/ WITH AD.) ADJACENT E EAST LF LINEAL FEET,FOOT REF REFERENCE WCR ANWEL CHAIR RAMP AIR ANCHOR EA EACH LG LENGTH REG REGULATOR WHRD WATT-HOUR DEMAND METER AL ALUMINUM EF EACH FACE LSR LATCHING SWITCH RELAY REINF REINFORCED WHSE WAREHOUSE ALIGN ALIGN,ALIGNLMENT EL ELEVATION LT LIGHT REPL REPLACE WK WALK ALT14 ALTERNATE ELB ELBOW M METER (ALSO DISTANCE) REQD REQUIRED W/L WATER LINE AWJ AMMETER EMS EMOMI(MENdT MAX MAXIMUM RET RETAINING WM WATER METER,WATT METER AMP AMPERE EMVT ELECTROMAGNETIC VOLTAGE MB MAILBOX R£TW RETAINING WALL W/0 WITHOUT AP ANGLE POINT TRANSFORMER MC 1/EAN'D£R CORNER RMV REMOVE WP WORK POINT APPROX APPROXIMATELY MANHOLE£OA EDGE OF ASPHALT RR RAILROAD WSDOT WASHINGTON STATE ASPH ASPHALT EDO EDGE OF CONCRETE MIC MOMMJT IN CASE R/W RIGHT OF WAY DEPARTMENT OF EOD EDGE OF DIRT AUX AUXILIARY EOC EDGE OF GRAVEL MIN MINIMUM,MINUTE S SLOPE,SOUTH WT WEIGHT AVE AVENUE MISC MISCELLANEOUS SA SURGE ARRESTER WTR WATER AVG AVERAGE EDP EDGE OF PAVEMENT MJ MECHANICAL JOINT SO SOIL BORING WVAL WATER VALVE AWG AMERICAN WIRE GAUGE ESMT EASEMENT ML MATOH LINE Sc SECTION CORNER W/VAR WATT/VAR METER BETW BETWEEN EOL EQUAL M/L MONLWENIT LINE SCADA SUPERVISORY CONTROL WW WING WAIL N BF BREAKER FAILURE RELAY EW EACH WAY VON MONUMENT SCHED SCHEDULE X LOW SIDE BUSHING o BK BLACK EXC EXCAVATION MOV METAL OXIDE SUROE ARRESTER SD SMOKE DETECTOR,STORM DRAIN X-BM CROSS BEAM V; BL BLUE,BLUE LIGHT-CIRCUIT READY EXP EXPANSION MR µ,+Jl.TI RATIO SE SOUTHEAST,SPOT ELEVATION XDCR TRANSDUCER � BLDG BUILDING EXST EXISTING N NORTH,NEUTRAL SEC SECOND,SECONDARY X TRANSFORMER BLVD BOULEVARD EXT EXTENSION.EXTERIOR NA NOT APPLICABLE SECT SECTION -RD CROSS ROAD BM BENCHMARK EXTD EXTRUDE,EXTRUDED NO NORMALLY CLOSED SEP -SEPARATOR X BOO BACK OF OURS FDR FEEDER NED NEGATIVE SHLOR SHOULDER XMSN CSN TRANSMISSION YD YARD fF FAR FACE,FINISHED FLOOR BOL BOLLARD NNEMR NATIONAL ELECTRICAL SHT SHEET DOT BOTTOM FHY FIRE HYDRANT MANUFACTURERS ASSOCIATION SIG SIGNAL BOW BACK OF WALK FIG FIGURE NF NEAR FACE SIM SIMILAR BR BROWN FM FORCE MAIN,FROM NO NORMALLY OPEN,NUMBER SL SECTION LINE m BRG BEARING FRO FENCE NOM NOMINAL S/L SURVEY LINE i BRK BREAK FLASH FINISH,FINISHED NTS NOT TO SCALE SLy SLEEVE FOC FACE OF CURB OC ON CENTER BSBL BUILDING SETBACK LINE SPA SPAC£,SPACES B/U BACKUP FOL FOG LINE OD OUTSIDE DIAMETER SPEC SPECIFICATION m FOW FACE OF WALL OF OUTSIDE FACE C CLOSE,CONDUCTOR SQ SQUARE FP FULL PENETRATION,FLAG POLE OH OVERHEAD CAT) CABLE TELEVISION SRVI 5£GMENTAI. BLOCK RETAINING WALL �w C8 CATCH BASIN FT FEET,FOOT OHTEL OVERHEAD TELEPHONE SS SANITARY SEWER STAINLESS �n CC CENTER TO CENTER FTC FOOTING OPHG OPENING STEEL,STATION SERVICE yo FU FUSE OPP OPPOSITE SSCO SANITARY SEWER CLEAN-OUT z0 CCVT CAPACITOR COOLED VOLTAGE cQo TRANSFORMER FUT FUTURE OPT OPTICAL SSMH SANITARY SEWER 1JV4H%E ilo CDF CONTROLLED DENSITY FILL GA GAUGE P POWER POLE ST STREET CG CURB AND GUTTER GALV GALVANIZED PAD PADMO(AVG STA STATION e CI CAST IRON GB GREEN WITH BLACK TRACER PB PUSH BUTTON STO STANDARD n i CIP CAST IN PLACE GOR GUARD RAIL PC POINT OF CURVE,PROPERTY CORNER STIR STIRRUP P CJ CONSTRUCTION JOINT GEL GRATE ELEVATION PCB POWER CIRCUIT BREAKER STL STEEL CKT CIRCUIT Gil GAS METER PCC POINT OF COMPOUND CURVE STLT STREET LIGHT 0 € C/L CENTERLINE CND GROUND PD PERFORATED DRAIN LINE SUBSTA SUBSTATION CLF CHAIN LINK FENCE ORB GRADE PE PLAN END SURVL SURVEY LINE A CLR CLEAR,CLEARANCE GV GAS VALVE PED PEDESTAL,PEDESTRIAN SVCE SERVICE r,9 � CVP CORRUGATED METAL PIPE GVLOW GRAVEL DRIVEWAY PERF PERFORATED SW SWITCH Q+ d CMU CONCRETE MASONRY UNIT H HIGH SIDE BUSHING PH PHASE SWGR SWITCHGEAR , CND CONDUIT HD HEAD PI POINT OF INTERSECTION S/lY SIDEWALK ir, AN M CITY COUNTY HDCP HANDICAP SYM80L PL PLATE,PROPERTY LINE SYMM SYMMETRICAL CO CLEAN OUT,CUT OUT HGALV HOT DIPPED GALVANIZEO PLC$ PLACES T TAN,TOP,TOPO,TRIP COL COLUMN HOT HEIGHT POA POLE ORIENTATION ANGLE TAN TANGENT �k COM COMMON HH HAND HOLE POO POINT ON CURVE TO THRUST BLOCK CONC CONCRETE HK HOOK PP POWER POLE T86 TOP AND BOTTOM I�s,N"4OMII1SH CCIIOONTTY CONN CONNECTION HORIZ HORIZONTAL PR PAIR TD TRANSDUCER I E ' 1 CONSTR CONSTRUCT HPS HIGH PRESSURE SODIUM PRO PT OF REVERSE CURVE TEL TELEPHONE CONT CONTH&ED,CONT1Pft10US HSB HIGH STRENGTH BOLT PRCST PRECAST TEMP TEMPORARY � 'VIA(IY OtSNit;CT COOR COORDINATE HSE HOUSE PRI PRIMARY T/L TRANSMISSION LINE ORDER 100002342 COR CORNER HV HIGH VOLTAGE PRL PARALLEL TOO TOP Of CONCRETE, CP CONNROL POINT HWY HIGHWAY PROJ PROJECTION TOP OF CURB OPERATION CPE CORRUGATED POLYETHYLENE 1D INSIDE DIAMETER PROP PROPERTY TOE CONCAVE SLOPE BREAK PIPE lE INERT ELEVATION PRTU PROTECTIVE RELAY TERMINAL UNIT TOP CONVEX SLOPE BREAK SCALE NOTED l CPT CONTROL POWER TRANSFORMER INSIDE FACE PRV PRESSURE REDUCING VALVE TOPO TOPOGRAPHY (STATION SERVICE TRANSFORMER) DFTR DPA CS CENTER SECTION,CONTROL SWITCH IN INCH,INCN�S PS POWER SUPPLY T07 TOTAL CSBC CRUSHED SURFACING BASE COURSE Ila INDICATOR PSI POUNDS PER SQUARE INCH TOW TOP OF WALL CKKR RMH i CSR CONTROL SWITCH RELAY IPA. INLET PT POINT OF TANGENT TRAM TRANSITION CSTC CRUSHED SURFACING TOP COURSE INSTL INSTALL POTENTIAL TRANSFOWER TRFC TRAFFIC EN'GR ENSTR INSTRUMENT PUD PUBLIC UTILITY DISTRICT NO.1 TS TEST SWITCH AP VD CT CURRENT TRANSFORMER OF SNOHOMISH COUNTY jgo CU COPPER,CUBIC INSUL INSULATIONPVC POINT OF VERTICAL CURVE, TV TELEVISION CULV CULVERT €NT INTERSECTION POLYVINYL CHLORIDE TYP TYPICAL DATE CYL CYLINDER INVT INVERT PVI POINT OF VERTICAL INTERSECTIO14 UDS UTILITY DUCT SYSTEM DM DOUBLE IP IRON PIPE PVMT PAVEMENT UG UNDERGROUND DC DIRECT CURRENT JB JUNCTM4 BOX PVRC POINT OF VERTICAL REVERSE CURVE U7EL UTILITY EAST WITCHINGARLINGTON STATION DE DEAD END JT JOINT PVT POINT OF VERTICAL TANGENT V VOLT,VOLTAGE S DEG DEGREE KA KILO AMPERE PWC PUBLIC WORKS CONTRACT VAL VALVE SWITCHING DEG DETAIL kV KILOVOLT PWR POWER VAR VARIES. ABBREVIATIONS g DI DUCTILE IRON KYA KILOVOLT AMPERE R RIGHT VB VALVE BOX Y DIA DIAMETERKVAR KILOVAR RAD RADIUS VEH VEHICLE D1S7R DISTRIBUTION S KW KILOWATT RB RED WITH BLACK TRACER VERT VERTICAL NOTE, Sg DEVIATIONS FROM THESE ABBREVIATIONS REVI DRAWING WILL BE NOTED ON INDIVIDUAL DRAWINGS. o S-4-82 �'� NW 1/4, SEC 12, TWP 31N, RGE 5E, W.M. LAND USE DATA 1) TAX ACCOUNT HUMBER, 310 5 2 2 002 00 5DD k EXST PERIMETER CURB 2) EXISTING ZONING= P/SP (PUBLIC/SEMI-PUBLIC) I POW R & LIGHT CO.R GHT-01-WAY 3) ADJACENT ZONING• RHO (HIGH DENSITY RESIDENTIAL)NM 4 PLyOET SOUND poW_,S FSLE NO CO.f�7g063 RLMD (LOW TO MODERATE DENSITY RESIDENTIAL) BASED ON R.O.SIFMO 4) SITE AREA 1.86 ACRES 5) STREET ADDRESS= 21210 117TH AVE NE ARLINGTON,WA 98223 1{ 6) APPLICANT &OWNER: PUDIC UTILITY DISTRICT NO 1 OF SHOHOMISH COUNTY I PO BOX 1107 EVERETT,WA 98206-1107 NORTH TEU(425)783-43DO II 7) CONTACT: TORS HEItDRICKS 4 3 51200200600 TEL:(425)783-5022 NAV AREA 5T YARD FAX:(425)267-6224 I 8) LEGAL DESCRIPTION: (PER DEED RECORDED UNDER AUDIT FILE NV(1)f.BER 927207 & 927174) GRAVEL COMMENCING 20 FEET NORTH 31 EAST OF THE SE CORPIER OF THE AREA SW 1/4 OF THE NW 1/4 OF SECTION 12 TOWNSHIP 31 N RANGE 5 EAST 01049600410100 W.M.:THENCE NORTH 3•EAST 200 FEET;(HENCE SOUTH 97.30'WEST , (MULTIPLE RESIDENCES NOT LISTED) PARALLEL WITH THE EAST AND WEST CENTER LINE OF SAID SECTION 12, HIGH DENSITY RESIDENTIAL (R l 360 FEF�T:THENCE SOUTH 3°WEST 2Dp FEET:THENCE NORTH 87. 30 EAST 360 FEET TO THE POINT OF BEOINING: II SUBJECT TO UNRECORDED PERPETUAL EASEMENT OVER AND ACROSS THE (NAVY SUBSTATION -.1 WESTERLY PORTION THEREOF,FOR THE MAINTENANCE AND OPERATION OF (n N TWO 110 000 VOLT LINES OF PUGET SOUND POWER & LIGHT COMPA14Y l EXST FEFdCE AND Ct)FNB I ¢ 12 KA'OWNN IS BAKER RIVER NOA AM BAKER RIVER NO.2. 1 89°58'24"E 36 .00' Z q POLE (44.t5` �! 131.00, EA-L 1 ❑ 4 DA L G/DPOL 1 o J¢ PROJECT COORDINATES I 7 A o 4 ? O O nl aq OESIGNATION NORTHING EASTING DESCRIPTION w m 1 BAY F 1 '' O1 436109.62 1328313.93 Fh( L101FE S'ROPoSEOT FENCE 1�6 w O 0 436015.19 1328313.98 BASELDES INTERSECTION u1 rn 10 4 m z O 1 435911.22 1328314.03 BASELDNE IITERSECTIWI N I W/RICHT-OF-WAY LICE I I O O O O © w8 ©O h Q4 438015.12 1328164.9b F�OF PROPOSED IFFENCE�B 0 1555b555 1 O 436015.25 1328435.78 BASELINE INTERSECTION nl -� W/RIGHT-OF-WAY LINE ,b O OI O MAR W/YELLOTI AP iti 4I B o 8 T2' 4361K).25 1328444.93 MAD HAI 7327, as a NI © 30 O7 436110.03 1328169.88 A� 91"WCAP M6'16 zo O BAY A O 0 BA C2 BAY 1) ❑ o I ® 435911.28 1328425.79 W SP /PU "v a� o� �q E_-_w _ N B9 58'24"E __ O�o _ W O 00 o, Z BASELINE INTFRSECT[Ul W/INSIDE 33 3 BASELINE f ❑ UZ t Q 415931.64 1328314.02 FAOE OF PROPOSED FENCE CURB a a I 4 II © AY B © El Q 436067.20 1328164.94 INSIDE FACE OF PROPOSED FENCE CM y ( B n 15 82' ! 11 436110.34 1328174.78 EXISTING FENCE POST 1` a I I o a 12 436109.70 1326365.03 EXISTING FENCE POST r 1 C 0 » mod I DEDICATED SUBSTATION EQUIPMENT. � � �o F( RECORDED 1 LAND OA DEAD END STRUCTURE F y ( BN(ER RIVEREES 8/3 V 1949 .. 00830700099900 ! ©115kV CIRCUIT BREAKER �m�43t" w LOW TO MODERATE r rmu[ tr rn p�NSITY O 115kV "V"SWITCH POLEt° RESIDENTIAL (RLMD) 1 EA-L ' / UD CONTROL ENCLOSURE SNO)i0U1SH COMITY 0 OA EA-L LINE ECR S E FtSOA LINSOURCE EXST FIBER 3 of BANK 1 SOII(CE VAULT r SOURCE BAN7C 2 y ❑ n r UDEM N / I ( I � I tW1c urattt oNsrMr 1n 1 1 l 9 ASPHALT LAJDSCAPIHG h I ORDER 100002342 I CRAVE LANDSCAPING GRAVEL LANDSCAPING DRIVEWAY El r ] DRIVEW Y DRIVEWAY !. / i 24b.2f' 1176' 8 / OPERATION EXST CURB AND SIDEWALK EXST CURB ANNO SIDEWALK l p o I 008307000998GO SCALE )NOTED a 3 ❑ o LOW TO MODERRATE DENSITY RESID£NTdAi(RLMD) DFTR DPA NW V4,SEC 12,T31N,RSE,W.M. 212TH ST NE 5W V4,SEC 12,T31(,RSE,W.M. CIc(R DMH (TVEIT RD) r` ENGR TQti APVD SRD 1 DATE �— EAST ARLINGTON SWITCHING 1 '0075690 STATION 2 ` J NIGH DENSITY RESIDENTIAL (RHD) 310EMIPUBLIC ( f 31p512003Op)00 SITE PLAN PUBLIC/SEMI PUBLIC (P/SP) 1 SUBURBAN RESIDENNTIAL NSR) 3 ' SITE PLAN EAGLE CREEK to j 4' 20' SUBSTATION ; BEFOREYOHOURS 20 10 0 20 DIG I !J 1-600-424-5555 1"= 20' SCALE IN FEET REV DRAWING o 0 S--4--C1 PLAT,TQRAVL71r I SNOHOMISH COUNTY P.U D. -. 1. - PER ROS A.F.N0. .. ! 2oI4uo73ooJ f ! SKCTION 12, Tb117tSfilF'31 NOM AARGE 6.EAST wIL.. - NOT LOCATTD TKG - SORVEY .- I ! SF 114, Nir'1/4 PPR Roy".1, 20141107300.T 2 !' , i t. p .25. ':50 100 . - NOT-LOCATTD no - J . D ASx+ - -A BASIS OF BEARiHG... HEST L1NE'OP NW 1/9 SEC. 12. o _ BEARS N 57 32 E. r� 1 Qn � r r - Mg c r f. LLGAL'DESCRIPTION f 3 ! 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FTyIlm RE¢A4 1►/.TBws CAP VAf CED is"rse:t CAP MARxm fHAw! a�s:�•' : .$[IRVEY NOTESi. 2f % NI 69'56'24'E RII S'CF L4{E 1)SURVEY PROCEDURES 89.11' 360.00' 7 f�J I QY Sf1r CA411P01-A1tDs`rArRVi> F1E16 TRAVIRSE,dc ID"rorA1'STA110IL FLT ' - N FACE'RY „ N OF P.tarf -.- POR tE' 2)11f§,F1ED RI 2 TRAVERSES USED 7TpS'SL VEY irEET'QR f7tCW,Tl105E. `� fOIAiD RF9t4 t/=low CAa: � S►ANOARDS COulAWED or wAc.332-130-o9A- �cq cq f 4 O 3)DLSrANCES ARE p1 fE'Er AND'DELbtlALs THaeEaF:. _ H$ y o a w 4)All GQYTR011pIO.ka'111.111N S1f0iTN ARE OF RECORD, LO ARE BAL_I Y �Q AOMPTEO AS REPRESMATRE or'T1fL]R PURPR'tTED P091rO0JS,ANo ao WERE VISITED DUR0WO IW COURSE OPTICS�IRYEY iFIAE55 OTHLRibs£ 33 SNCVWs7f COUNTY P:U.o.no..'1' f a bbrti a1 EAST,ARLRTOTO.Y SUB-STATION! tou ` h : ASSESSOR PARCEL,3105120D200500 S) TIES SURY-Y DOES HOT PURPORT T9 MOW ALL EAsa1ErlTs �•�: :` f. p '� 1.664/ACRES' r1N• f : - I. :SURV1s'YOIi'S CEI; 29 MCATE gr RR SPGIE. .: - 'T•• - -,' - - - INS MAP;.Cb RECILY REPRESENTS A S2 Wr 4FJt0E 6;UE d4 UhVi* 1 -1fED1.1tPXTI MARK.... ' NY MECIM PI.COWQ"%E IVTH.THE RMAREMENT3 OF rut. 91 PA1E WW 12zb0'' REDDRAVJC.ACT'A7'T17E'REGU£STOF SIiOVIOMISf!OOWJTY•. - !2r � 360.00 D u'13 P.U.O.11 B!MAY 16. - rf OUARTEB DQaTm: wry 8.9'S8'24*E 212th ST,:(TVEIT lw.) rouTm ri/R-SW jr ylg )b 'T'CU7m 4x4''-. R i�OLaDRE7MR 11rLM1FR+ CM'_ .. .fW14 As r/!B taahEx. -OWPIETE i1Q41A4Hr _ R1LN�RO.F. DaTf': -eITH NYERTEo NAe. --- — •-- .- —— .— — -- .. - ` PR .LAlroSUR►>:raa - :FOGPA CASE CRkC+tohTn7alr: f...'�.0'�0 :~__ W/2'Bf6tSS n�c.uavon•Puv afrLa...� : REas1RA710ld Na 34137.- S WIOARY LANE ADJUSTMENT SNOF101 fSN1 COUNTY P,U,D, NO. 1 AND SIAVPFD LS'12i16' STtOHOMISH COUNTY f A.F.NQ 9505095003. ASSESSOT PARCEL: 3105r200300600 :i 247/10!w XNNLR �� 4 05+l ACRES ITOR�S D a�cic ullurY axtxr �� • ••�- ••AU� GERTI!<"1CATE .RECORD OF STIRVEY • FOCFm/ttPAR WAR�aFD:IS'f2716' EYE' MR RECORD.TkS__�_;DAY OF � 20f8. � .-- --- .. Ar ' . AC jN 800;r - OF SVRWn AT PAGE ORDER t00002342 -.:AT IW REQUEST Uf HAWSE - AW !41�r"?S 1 _ SET T/2"RESAR W/TELLOw CAP'rlAl 3413Y t+mc BY p p p 1 oPERATTOTI ••,.CovNrrAwlTaR I1 f, 1.'p,'•i - SCALE tFOTED i. .FOUND efMWFHT+W CASE i o Focb.rtEeaR As xorED SURVEYORS:NARRATIVE:. 6)6 AF# DETR DPA FOWJD PLAY NCkWENT... URiEY TI£ARWW AHd•SECWH'W?n?OL 0450 till NARUSEN k..: ASSOCIATES.RECORD OF SURVET:,SNQHOlt=C04CATY Af.Ha F. A -SNOHOMISH COUNTY'P.U D. .#f CKKk DMH F NO 'AUDITORS F11E UMBER•; '' 2of41r07600T I HELD 2Ro•FOR THE bmin now or 2I2TH ST yE'' �ps etr 1 (Two RQ)'AS l BELIEVE-THAT WAS THE DTTENT'OF THE.LEGAL _ �� I PS RECORD O SURVEY - RECORD OF SURVEY --fD44 OESCRIPITQY.:DO$AFFECTS THE NORTH/SOUTH LANES a5rAT10E y� COMPARED-TO RECORD CALLS .I•�� SCALLi SWET.t or J14 ,}ND 1A p awtrl 8M R¢L i HAR�NSE CW.'t Std YEr.7 81oc Ar-e iLO RtYdMTD8Y• 125 FAST MAW STREET,SWIE 104 DATE54000P(a mtmrom&bSOSEAQE Cif SV84TAI1R"I�DMG\FARE pPK SJDSTATfol1 R05DW _ , OyWA06272: S12ae s aT TE!' 36o rs9-78n Sw 1 a'KW EAST g ' .. ARLINGTON SWITCHING a STATION z RECORD OF SURVEY �m Rt:v pRAwtt:c 0 1 S-4-C2 .o i SW 1/4, NW 1/4, SECTION 12, TOWNSHIP 31 NORTH, RANGE 5 EAST, W.M. 1 1 I I _ %XbW COWM4 PER ROS 2 I JI1 f AJ.!M 01 5 10 73 0 0I I I I ` SURVEYORS NARRATIVE f11 SIAVEY BEARAW A49 SECPM ararROI.BASED ON N4RVSE4& 7 }rng ASSOCIATES RECORD OF AAfi£Y.SNO10M COMTr Ar:Nk 201411017.001 1 fiaD Mo'FOR THE NORTH RDA OF R1z1H ST If zL^y I 1 (nVT RO)AS a BREVE MAY*AS THE WMIT OF THE LECA£ 0 25 50 1 0£SCRPTKYa. D"AFFECTS THE"m/swm LAWS MYANC£ f I COVPAIF£0 To RfCORD CALLS B REVISIONS 1 E OF BEAIGtiO MST MEOF MR f,32 SEC 12 Fos o REBxv r/nugr CAT•umm 7737r� BEARS N 5'16'32-E 1 Z FD O 84R V/M406'GIP Ymao'27mr YYY LJ p o I I 999 �=: LEGEND SFRl)CA!DATIAV O Z a` R£COR0 OF SI,RIEY Ijjj 68-4 A.F.NO, 2014LfD75001 7*w n ' • SET 1/2-REBAR WIMLOW CAP'HAI J4137� £ST7Al "COY WS r�^n ` f X SET PX HAIL&wA VER LS'J4137' ` !r0.w aEe.w11/mtOr CAP VAeirO•f%ll• f rw1 D llawv£Fa7 L4 CAW IOV'0!WEAR Ir/nUOW CAP � r 0 FOM iR B PPE AS I;& FOCH77 3 1/2'A'MONKr IE AIM VIPApD Y%]r' I O rOVlap RFOAR AS NOIEO ADV.f of WAS'6U.+,4£atf P�6R j r Aa,L tsoF.�ao' Q^ j ® 1`01RID PLAT VOYUYENF RUSH•/WAIEL b A SEr RR SPotE 10 TN PtR" [tEW15B.6r �a ,, � z '� a$ W e Taw SET REBAq win EONTROt RED CAP YARtf0 z fy y SYdiOLDSH COUNTY P.U.D.NO. 1 I ELEY-15151' W 1 ' � EAST ARLINGTON SUB-STAD&I gfi u m ASSESSOR PARCEL: .3 051200200500 } i I.66 4/-ACRES LEGAL DESCRIPTION: W` 2 C, Y UTdREC0.'+DEO EASEVpE7 2 , UN N I FOR BAKER RIVER MES l rxARM s.�E D�aT2M sr '1 PLR Ii[CGRD Of SrAQ1YT"SMOIIOI/c51f COAT"AF.000,20 a070SSD72 r ASSESSOR PARCEL NQ 31051200200500; n 1 , (PER OECD REOORDE)CNDER At*f*tS TILE MjVUR 0272D7 R 927174 ll str PA SP.2 7FM N {y (] 04M0f,�T COMENONG 20 FEET NORM 3•EAST C4'�SE CO®4'ER OF W SW 1/4 OF x W a� I 122.50 THE Nr 1/4 OF S£COO4 12,TOR VtP 3f N.RAW$EAST,V11-T �N I__ ^ .Tfidl70 20AY WAS ]HENCE NORM 3'£A$r AV FEET: y NCI WA1M4: !z� -- __L-T 1301"' �d 0 I OTHENCE F S£61 cTO`lil$a712 rfYrAR1LLEe AFM riff EASY Alm►£Sr CENTER LR£ �Q F`,4� �o 05vm1E - -- -. - -.-. L--__�"-_- __ O+ENOE Sp/1H 3'0.�Sr 200 FEEL +C o U.- Wrftlry AX II ^I H 89'5624"E R/2 sAn,yam Wh"NOQOI 67'30'EAST 360 FEET M THE PONT OF BEWNNq m a a ^jyP$D NAp iiz 212TH ST NE - (WEVIT RD.) k S a9`5874•W HMO AS Ina ece rR jz o o L—_ �-x-��\-�--— —— — —------ $LB.ECr TO P'.*FLOwro PfRPErUAL EASEVfNr orit mii)ACROSS TIE q - _ �—__ - ` 169.73' MAD CO4G WAMENr WESTERLY PCRMW DOMCF FOR RE VANMYA. f AND OPERA OON OF TAO Q J 11 F0.M Ft8A4 s/a"0 CAP I/Y LIRASS OSr WXWO'12716' IIA000 WLi FA£$p�FVCEr$OUF.O POi�Jt&lJOFT COIPAYY 10.`OMa AS Q 1 a 2+k s6Y OF CR+tR BAILER OVER Na 1 AND BAxu fdVII1 NQ 2. J yf SURVEY NOTES• en j MAW'91FAR L,Ao?D AS 122M• 1)"WY PROwtaE$&fO17PVf71r: � X� rcm PO4 PAt U.0 is1P7H' J ON 9TE 00ERSE A!m$OTAL S iYTO IRA1fRSE&10'TOTAL STAPQNL t3 a000' I 2)Br nRo rrulERsfs USED Pr Tess sARlfr vr£r OR EACEFO THOSf 1 F�Ama 1y� l N B5'37'F1•E f $MI"40S OONIAM0 N%4C JS2-130-0GA IQDO' ! 3)MUNC£S ARE N FEEI A47 DEO VALS INEP£OF, n k S41OHDViSH COUNTY P.V.O.NO. F I{ A55£5504 PARCEL: 3105120OJ00600r 3 A ALL C SINT DVE F THOR R S ORTE ARE O°RECORD,ARE LOCALLY ACCEPTED 1 1.o5+�-ACRES y,1 I COWXNTF OF GEAR PtAESS OO ROWSE YO ALA WCR£IS9rfO OIAPlIL .rf d THE COIA7SE OF R85 SRLI£Y tAaESS OMERMSE NOTED. z1 bj� z DLO I" N 6)MS AAi1£r DOES NOT F'OWoFr TO 9FOr ALL GSEVENTS c' 34 ?y UTILITY NOTE: ALL WO ROTOLNO UTILITY LOCAWVS ARE&WO ON STRUCRLRES LOCATED BY CL^00 III Y V11 t FIEW VEA"EWNFS Of JAN£MIS ASO LOCAWS'S PROVIDED BYr �0 0 m I SNOHOMISH cov?4TY 435"SF NORM BVQSM rur NOQM S WA s6DLs k { ` f (425)68d-239D � CL Z O 0 Q�O PUBLIC VILITY&'STRICT?a 1 INC$URDETW W.45 NO OWRAYTEE Mlr M uMXRCRO"UTILITIES 940M U 1� O 4 OOIPASE ALL 9.04 UTEITES L4 THE AREA,VINLR N SERVICE OR ABANDOWD. � U' Z ORDER f00002342 TT4£516tL£m DOE$NOr WARRANT THAT THE LINDERMOWA7 UWF%ES SHM APE O w E4A6'� — S 895614•W LOCATED AS ACOAA�Y AS P0549tE FROM THE r FORVA1IGM PROtDM k E 4 a"Ic� 1 EAT015GN Dc aY 7E5r 12d rj T+16 ETR EW U11LITES SHOWY ON PLANS ARE r0 BE I£fErEO H092o'fTAiLY ATA) ; 0 OPERATIdaa I I EASLIgNT SW1H OF 2120E EREA7ES A IE F"EY POW TO ANY CU451 Xr0( O l rlRa'>?FFi: TTE 57rPzo-'ERn x W "r SCALE Nis J= SURVEYORS CERTIFICATION.' O L. 4 I LOCATIONS 90M ON ASS VAP ARE SA"O4 A 11110 9AR{£Y BY NARVSEN AND ASSWAIES ON"9 6 OaRO".WAY I.O 171K 2016 A RECORU£D LY FY10�.3A7[ z DF7R OPA M&80"ARY 030RVATTW 1S BASED UPON A RECORD OF 9ARIEY BY HARVSEN 1 J 1 I A40 ASSOCIATES AVOMNR'S FILE NL'R 20f607o6 M LOCATION 9ARIfY TFAS CHKR DMH +-�-�- =0RW0 WDFR Ur SiWtRUSICH 1N OOAY1pWA4C£WPM APPLICABLE STATE AM Via pY SFAADARDS At Tiff AEOU£ST OF 90"Mf C"rr RUDL j01 IN WY, ,` I jX 12 }- zola DRAYTYO: ENCR �ti I I*- l-k- S APVO Sad —i— �AII�Ob s/WIC JNXX KEY Ic01.GRo it,CAw"rt%PROFESSONAL LA4o 9ARIfYCR {OATS) DATE C\f75ER5�RttEfd\LOCAL SEfTiV'S\7EIC' E W+.S791W0.E L4C 9A?S rAiaplDY 07/I I/N16 73TN^R5E R£oSTRAT0,1 W 34137 I r BRP.T:I` I OP 2 ARLINGTON SSTATIONG E SURVEY DRAWING IMAGE REDUCED IN SIZE TQf'SSHEET"�OF 2 TO F'IT WITHIN DISTRICT STANDARDe TITLE BLOCK AND BORDER. - DRAWING IS NOT TO SCALE. REV I DRAVIING 3 0 1 S-4-C3A LEGEND SW 1/4, NW 1/4, SECTION 12, TOWNSHIP 31 NORTH, RANGE 5 EAST, W.M. L<Ar r • PA1flENr(nPJ Ser PA'REBAR W/TELLOH CAP'1W U137- a I X SET PK HAA.&WASHER LS'3037' ' r 111 tW`t(R LM1E PAW µ FO(WD MLYRNfflNr IN CASE a FOCC 6 FAwl7 OO FOlR(D tRAY WE AS NOTED Q- ———— ——PArouOrr(TIP.)-- p FOUW RESAR AS NOTED a 4 p—P— ID FOIRCO PLAT LIOMAULNT 1 1 A SET RR VW METH Pv%'CTL 19 raw j3 Q BOUEOLR T 10' j ! REVISIONS CATE POST n I �� ell WATER YAW 11a h 'a f; Q BASS Of BEAR p HmO HCA£ TLEr LLYE of NOV 1�4,slc. Iz ® 1RR7"mm CONTROL VALVE j BEARS N 5 E CULVERT END f1{O z PO'AER VAULT I I! ^ rn a S5G4 POST y VER DATUM a ; - - 3 I 14 K "O 4 3 W CEDAR TREE NAMA&��BY CPS J r k 0.I�11 1 Q 5 a OT TELEPHONE PEDESTAL N D95824'E `.' .3 1 n ! J n►j E 0 JA%'CDW Box p� N NET P&MR POLE W/U.C.FEED 6R' ! � � a 0 O F a~aYYar Jena o . 7 , -0- POAER POLE � � +�' � � ALL S>.YS F CUv ANCHOR O EJ 11 4 TIRE H/LiRA177 a J J; a !' W o li+ � 0 TYJt ntc C'dtlur(nP.) L WATER FAUCET 4 ■ s �> Wx EH WATER METER ■ rI/I 4 , 4.4 STER POSt(TM) / J a —'a"' CAS[DV£ fl / • _ Iu N —r— POAER LAVE p n [7 C7 Q fl —w— POAER ME(UP"RCROUND) El 'f13 `�- —1a— STOW DRAW LAVE , 1 ❑ Q _ ;.;>.; - x $ r h Vrl1 RT.Ud5 za t —tom TELLPHaVE LACE �?-V�.� • `-oX'G va(rrP) 13 O x O s _ +f1173 yJ is Y� 3 —ur— TELEPHOW LINE(WOFRCRaWO) l O fl Q ..•,■'' D Q / < 4s —.— WATN:rt LPLE • ; / f~,trm I 0 ASPHALT PAYEMLHr L7 CJ Q A> a m a CRA\EL n D E7 O EEt , R.ALL 37ES^\ MiCRETE 3 vATrzEi 1 fl ❑ 0 PM g� o/!r T�71cv u�S }lI I 11 m.--•� LOGE OF LECETATNkC 1`1 6 PRiCISr FARE OW-04(rM) y O O a �rr-�'i� �•• � 1 _ �-a I 4 .•A�� I ` ` E] a ❑ ❑ �..r.. ...... cl stm SICO a I 1 n Ob` ■GN elm o rD.p mI, �,, ► 1 ce YAO to ftw ial}L 11111a...•• .. ' a r 7 ` ! U Ep 1aUri R 4=fss ss n 4'a v+ I (� }� sv c s f.vsa+4 ,- '' % m ce Imreruca CL OMN L a �t 1 12,0V F E.132r3 m gL.=90 ■ ■ �P1 ze pP Tr E-Iu.7s p 0] MAWLE !>uK U/� 1uV0 •. _ $' E i. .�. .--..,�•_. F+`� U 10 5140HOM35H COUNTY tt[LIDS' - D r-Fn ti d P =F vP - - Q ruT .n .J,"" r PUEM UTRITY DMIMT H)1 u< ur vf�1l9582+'a ,JS¢ - $dx l{ C F� C7 --—--—--—--r _ .,, �+ar rwr- '-' - va a'ca�iv.. eeM- �4� � PB SQD LR1 Rv.l3f.7 G O. Cr-O—G C 6 ~ 1 T.''. l 4OAME=1 71l5N3V � O Z ORDER 100002342 LQ ck 0 Q OPERATION .�---—�.��—._ - - - .. - __.._.___ _ -— -—•''•'._ - \ mr>ta Lwt sv�E rLiLoa b COYmeLAY,Da mtoP T- 2I2th IST. . YVEIT RD). � � SCALE NTS n Z OFTR DPA /P �roAw Wa sua rLA.a/. fQ1D AS r/16 CoraLQ ! A _ J Ka" n _ g�r s (av raLro cae rwuo-xr C / APVD ,TW aoa vAsao'1n16 ►.•J 2 �J Arr�e Nuc r\v LA GATE I! 1 AMOR u0Ys7v y zrk 2ss ar taav« DATE S/ 15 1 C:\ustas4�ozalLax StrTrdcS\rtao�Als+Fa+sl_srsl\tAat cek srssrATtaor,07/11/mu NiJJEE.4: z or z EAST ARLINGTON SWITCHING STATION TOPOGRAPHIC SURVEY A§ DRAWING IMAGE REDUCED IN SIZE SHEET 2 OF 2 $� TO FIT WITHIN DISTRICT STANDARD de TITLE BLOCK AND BORDER. DRAWING IS NOT TO SCALE. REV DRAWING "g 0 S-4—C3B :--- bo GENERAL NOTES: •�i= 1. THE CONTRACTOR SHALL APPLY ALt KNOWN AVAItABLE,A.'D REASONABLE METHODS OF PREVENTION CONTROL AND TREATMENT bF STORMWATER AID NON-STORMWATER I DISCHARGES.THIS INCLUDES THE IMPLEMENTATION OF THE STORMWATER POLLUTION 4 PREVENTION PLAN (SWPPP),WITH ALL APPROPRIATE BEST MANAGEMENT PRACTICES - INSTALLED AND MAINTAINED IN ACCORDANCE WITH THE SWPPP AST) THE TERMS AND CONDITIONS OF THE CONSTRUCTION STORMWATER GENERAL PERMIT. 1 E 2. REPLACEMENT UPGGRA THE DINNGSOF THE SWPPP FACILITIES fF�FENANCE, 1 RESPONSI6ILIfY OF THE CONTRACTOR UNTIL ALL CONSTRUCTION 1S COMPLETED. y 3. ALL TEMPORARY EROSION MEASURES SHALL BE INSTALLED BY THE CONTRACTORUCTION. 4 4 INSPECTED AND APPROVED BY THE DISTRICT PRIOR TO ALL OTHER CONSTR 41 4 v�i 4. THE SWPPP FACILITIES SHOWN ON THIS PLAN ARE THE MINIMUM RE IREMENTS SWPPP FACILITIESSISTHALL BE Uf�ADEDD DURING NEEDED FOR XPECTED MRM� EVENTS AND TO ENSURE THAT SEDIMENT AID SEDIMENT-LADEN WATER DO NOT I 4 : LEAVE THE SITE. i NAVY AREA 51YARD 5. THE SWPPP FACILITIES SHOWN ON THIS PLAN MUST BE CONSTRUCTED IN EXIT GRAVEL '1 EXST GRAVEL CONJUNCTION WITH ALL CLEARING AND GRADING ACTIVITIES AM IN SUCH A MANNER AS TO ENSURE THAT SEDIMENT AM SEDIMENT-LADS!! WATER DO NOT •t ENTER THE DRA114ME SYSTEM,ROADWAYS,OR VIOLATE APPLICABLE WATER QUALITY STANDARDS. NORTH •? ` Ir 6. THE SWPPP FACILITIES SHALL BE INSPECTED DAILY BY THE CONTRACTOR AM I j MAINTAINED AS NECESSARY TO ENSURE CONTINUAL FUNCTION. 4 y i�•• OR OF I.M.-WAY SHALL BE CLEANED BY :"-••••I•^••-•••••••••••••••• ,h0 Q3 � 7. THE �N S.4�P�ORKFSTOPAPLAG�E AT NOADDITIONAL COST TD�IHE �D1�STRiCT4� L BE THE ---- -- T TOR. % i' ": ❑ O-: ,+ S. COtNTRTOR4S BOIL£RESSPOTF158IL[DISTURBING ACTIVITY� TIN£ LIMITS ANY LOCAL OR STATE OFOES F GROUAD cn DISTURBANCPERFORMING 1 L 13E LOCATEDNY ANDAND MARKED IN THt'FIELD AID APPROVED BY 7 ! f THE DISTRICT. w y8. HIGH VISIBILITY SILT FENCE SHALL CONFORM TO STATE STANDARD PLAN I-30.16-00. tc !' •i I0.STORM DRAIN INLET PROTECTION SHALL CONFORM TO STATE STANDARD PLAN ".............. ❑ ❑ 1-40.20-00. BRUSH ...... ...• '-- ' ----- EXST GRAVEL KEY ENOTES: L. ,h9 1 1VISIBILITY SILT FENCE,SUP C233. r ! St h6 Q2 INSTALL STORM DRAIN INLET PROTECTION,BMP C220. z �.... ❑ -❑ all ' I - ❑ - Q3 CONSTRUCTION ENTRANCES,BMP C105,UTILIZE EXISTING SOUTH AND NORTH GRAVEL. � ❑ ❑ �; ©. ❑ ❑' ElDRIVEWAYS. I ! I i ;O i ;❑ El; ❑' ®STABIL12EO PARKING AREA,IWP C107. ! ' vFoi i❑: Q' El i i i b Ass ! 1 �, ❑, LEGEND �a , j i "• -- El El Ll + LIMITS OF GROUND DISTURBANCE 00 �.:...... .:EXST GRAVEL ..... El l 159 4 , 00 1 El El El EXSr GRASS-L1N£0 SCALE ;' 9��d r EXST GRAVEL 1 � �• 4 r: �1" � € ! 4 t,• BRUSH• / 'Si �,,1 ••S. - I ..\3T , L j/�` t ! i- ❑i } ' S • ' 7 I :. ..... -. ,- .;....-. APISH CO(1NT7 D S T '. EXST GRAVEL v O Eh, �� T �� T i� EXST GRAVEL •• AVEL SD -" ••; ORDER 100002342 i �^ OPERATION •.l -., G G- ------------------- ------ SD SD AL 2. }, 2 •,3 •' ,•2 \�- SCALE NOTED DFTR DPA 212TH ST N (TYEITb) .5s" .y� II yam' �i' ;` CHXR DMH ..g3 1 EUGR IN ,l 41 w •�. Jlua W V. EAST 't l i t'`• ; i' _ •1hu ARLTNGTON SWITCHING STATION STORMWATER i POLLUTION -- SUBSTATION +i• ; ' PREVENTION PLAN ) , • EAGLE CREEK �••i ; :! '" CALL 48 HOURS BEFORE YOU DIG 20 to O 20 REV DRAWING :f STORM WATER POLLUTION PREVENTION PLAN 1-800-424-5555 ,"a 20' SCALE IN FEET 0 S-4—C4 a `, ♦60`• GENERAL NOTES: 1. LIMITS OF WORK SHALL BE THE AREA BOUNDED BY THE SITE 1 PROPERTY LINES THE EAST EDGE OF THE GRASS-LINED SWALE WEST OF THE SU)BSTATION,AND THE AREA BETWEEN THE SOUTH `1 PROPERTY LINE AND THE EDGE OF STREET PAVEMENT.2. ELEVATIONiOFF U9Y EET EXCEPT SOUTHEAST CORNECK R SHOWN t ON THIS DRAWING. l �TBM •, N KEY NOTES: t ( EXCAVATE AND REMOVE SUBSTATION ROCK UNSUITABLE Ilh'D SURPLUS 1 3 LLJSOIL AFTER DEMOLITION OF ALL SITE IWOYEMENTS AS SHOWN ON � DRAWINGS S-4-D1,D2,ANO D3.EXCAVATE,FILL AHD GRADE WITHIN 1 Q THE LIMITS OF WORK TO THE ELEVATIONS,LIVES,AID GRADES SHOWN. Q2 CONSTRUCT INTERCEPTOR TRENCH WITH CONCRETE CATCH y l NAVY AREA 51YARD BASINS GEOTEXTILE FABRIC AIM 6"HOPE (SP)PERFO"TED P1Pf.. y I DRAIN rtOGK SECTION DEPT�i MUST VARY BETWEEN 2.5 AND 1.5 WHERE YARD ELEVATION TRAYSITIONS FROM 159.0 TO 158.0. CONSTRUCT 1'^2"COMPACT THICKNESS THICKNESS CRUSHED SURFACING BASE f COURSE (CSBC)(MIN)AND 4'COMPACTED THICKNESS SUBSTATION ROCK THROUGHOUT THE AREA INSIDE THE SUBSTATION SECURITY 44 pp EXST FENCE AND CURB �h`�,• FENCE. STRUCT 5" ED ...................... O THICKNESS CONCRETE IPERRII BTEF.RSTAAW1 H 6 W x 12'D /: -------------------------- ��_ F-MJ.}2-03 WITH EXPANSION A)vv0 CONTRACTION JOSHES PER STATE y 'L/ - T Si1JfDARD PLAN F-30.t0-03. 6 !� -- r 1f- 1 - -i-----^--------- ----.V� SD,.--------------t+---------------------- -�-------------------- -- K�IPYOTEF 4 70 6�'W z 24"D W/REBAR REDiFOCRC�EhGOSREFER TON � S f j 1 ! CB6 i i r r C851, SECTION B AND DETAIL 1 ON S-4-C6)AIM CONSTRUCT THIS CURB f 1 ! �___ - i ' INSIDE THE CIRCLED AREAS SHOWN ALONG THE EAST SIDE (APPROX S 1 I r r TRANS)Am WEST SIDE LF).MAKE CURB HEIGHT rr <• / 1•:1 f I a•'' •.`a♦• CB r............, f r O9 1' JOINT. a ti f .................. e O ; ©6"HOPE TYPE S PIPE,C64 TO 082 AND C83 TO C82. X N % f /'I ! ' 11 +':� .,+Q,',' 1 ♦60 7 O INSTALL IRRIGATION PIPE SLEEVE,6"DIAMETER SCH 40 PVC PIPE.SEE DRAWING S-4-CB. Ir { Dr r /r ! i :• N'� ••.�..�.� '•.�A-;_--_-'� ;D D i _d_i •..�_f,1a,f]••••••• �Q p�,•--... _,,: _Q� _�g�•: i j r ts.} CO® RUCT ASPHALT DRIVEWAY.SEE DRAWING S-4-C8. l 2 3 \ NST CONSTRUCT GRAVEL DRIVEWAY.SEE DRAWING S-4-08. N - I l I : ( § r'.•... r? ai ;Cl i i 0 0: ;Q: :0 O; !0 0: --' i Q e 1 ? ®THE EAST INVERT ELEVATION FOR C82 IS c� ------ --- CALCULATED, FROM z r i = r N I h AVAILABLE DATA AND MAY NOT MATCH 1 THE FIELD INVERT ELEVATION OF THE EXISTING 4"PVC SO.ADJUST 4'SO SLOPE AS REQUIRED. z L0 =cl+• 04r i 1 j 11 CONSTRUCT THE LANDSCAPING AREAS 1 FT LOWER THA4 FINISH GRADE ELEVATION WITH THE EXCEPTION BEING 1 FT OUTSIDE ANY p, 1 CAST-]N PLACE CURBING CONSTRUCT 6 INCHES LOWER THAN TOP OF T z 4 CONCRETE (TOO). O i I i i ? „ - f r 12 REMOVE EXISTING CONCRETE DRIVEWAY APPROACH AND REPLACE LM 4 t --1 :r1 r CONCRETE CURB GUTTER,AND SIDEWALK PER CITY OF ARLINGTON ap 4 l D O i / i 1J i 'D y r I 3 STA40ARD DETA�L R^170 A`� R-180. -a 1 ❑ _ E Q. :... Q optN1 J + o r re r r 3 1y h l f T Iis ,.... ' 1 �' i i � ♦+ f `, _ '��r `�• i It ID,1111 •\ VERTICAL DATUM 9• . p j r i .... r NAVO 88 - GEOD 12A 1 --- - fs . ' •` •`y r ESTABLISHED BY CPS 1 L , D; '` it I r +''� ••15a... T8M #9r 40 $ °o- r �`• i❑ 'D i _D i y Q i d-� t {�' _...f'd i {SrB I r V •-'�... FOUND 3V2"ALUMIMI DISK EXST GRASS-LlN£D SWALE �; i \\\ - 1- W H _ 1 WITH PUNCH MAKEWAsf O FLUSH W 4 ; I ) i 1 ,: -+•: i i--- �C]� -......... - i�; --- -._TO ELEV = 158 siQt GAY L. �p ti r t SET � WITH RED CAP MARKED AO1�Lgt �� , � N ; l i i i i 1 ~�� 1-...........?• ••( •._.�' ELEV 153.54' •' h 1 1 I - _ r -.............»...--..---------• ---...... r , SO -•+- -. .• 1 ..�1 O - «L - _....�� C8 r- SNOHOMISH COIRNTY 1 I'lt�1c IRRrrr asrlCcr 3!1 ® ' a DRAINAGE STRUCTURES SCHEDULE _ .. .� Nh 7 6' d :• ❑..... ORDER 100002,342 1 F Ca3 •'G f>ESECNATION WSDOT NORTHING FASTING EGRATE/RIMLEVATION PIPE REMARKS - ... -.. ...-...--.-.-... -• -.. _ PE ELEVATION INVERT(S)(S) OPERA TYPE EL !N F T[ON i 18"SD 18"SO r 12 j TBM 82 E ESTING 4"PVC N f53.10± 1¢"SD C61 �pxN ETE 435900.51 1328407.97 $54.09 18"CMP W 152.75± EXISTING CITY CATCH BASIN SCALE NOTED G G 6"SD+ G G + ♦ `.� Cg1+._,-• .... CATCH BASIN 12"CPP E 152.75$ +•+ ' 3 CONCRETE N 154.85 W/INVERTED FRAH€ & GRATE OFTR DPA _._:�,-. s 082 INLET 435918.77 1328393.69 157.65 W 154.80 PRECAST INTO 24 PRECAST ; 212TH ST NE E is4.25± RECTANGULAR ADJUSTMENT SECTION CHKR DM bar �6 ,�60 •1�9`,: (TVEIT RD) `' r ti �3 CaRRTE 435909.58 1328380.69 155.84 E 154.32 W/UPRIGHT FRAME & GRATE :..�' _.. .. T�_..�.• B B 1328393.68 158.08 N 355.75 P/INVER 1D FRAME 6 GRATE APVD .- •- •-- " w C 4 TYPE 1 35936 2 W �..- . 4 yN 4! w + S f55.25 RECTANGULAR ADJUSTU£INT SECTION CONCRETE W/INVERTED F% & CRATE DATE '/ryIS y. INLET 436101.07 1328423.44 159.00 155.75 PRECAST INTO 24 PRECAST RECTANGYRAR ADJUSTMENT SECTION C�5 CONCRETE NVERTED FRK & GRATE EAST j `-, i l -•-f" k C86 436102.34 1328182.78 159.00 155.75 PRECAST INTO 24 PRECAST ARLINGTON ( ;• ' _- rr ♦h ., ENL£T RECTANGULAR ADJUSTMENT SECTION ++ 1 i +'/ :' f~� ti• r• CB7 CONCRETE 4 W/INVERTED FRAME & GRATE SWITCHISTATIONG 3 1 E l r h 35936A6 1328169,5E 159,00 t55.75 PRECAST INTO 2 PRECAST - Il ', r .• `• i DRAINNAGGE PLAN E EAGLE GREEK :'1 J ` •; E , RECTANGULAR ADJUSTMENT SECTION E ' 1 SUBSTATION /;1•. �h S$ ! qq f ' 1 := CALL 48 HOURS 20 f0 0 20 sA BEFORE YOU DIG GRADING AND DRAINAGE PLAN 1-800-424-5555REv DRAWING ,"= 2D' SCALE IN FEET 1"- 20' 0 1 S-4-05 I 4"THICK COMPACTED ENMESHED GRADE SUB!:8STATION ROCK SUBGRADE SECURITY FENCE4"SUBSTATION SUBGRADE CQ`NC F£CURB FINISHED GRADE ROCK 4"THICK COMPACTED SUBSTATION ROCK.TYPICAL. FOR ROCK PERIMETER 4"SUBSTATIONR _ SUBGRADE NONWOVEN GEOTEXTILE ADJACENT TO SECURITY FENCE. FABRIC OVERLAP FULL 6'1Y z 12"D CEMENT CONCRETE q TRE,& WIDTH AT }4"CSBC PEDESTRIAN CURB PER STATE r-2"CSBC 44""SUBSTATION SUB-SUBGRADE ELEVATION STANDARD PLAN F-10.12-03 WITH SECVRETY ROCK EXPANSION AND CONTRACTION JOINTS FENCE PER STATE STANDARD PLAN F-30AO-03. NON-WOVEN GEOTEXTILE e£GRASS-LINED SCALE FABRIC OVERLAP FULL FLOW LINE TYPICAL PERIMETER AREA TRENCU GIWE AT 14`CSBC TRRRBWIDTH EEEYAT[Ok SUB-SUSGRADE VARIES TOP FENCE CURB SECTION WITH 1' CURB DEPTH 05) COMPACTED CSBC 3'-O" FINISHED GRADE �`"4 y_°" W*CRUSHED DRAIN 10 ROCK PER STATE ' SPEC 9-03.12(4) I - a 4"THICK COMPACTED ISUB-SUBGRADE a E,SEE IE,SEE FINISHE SUBSTATION ROCK 4"THICK COMPACTED It DRAINAGE DRAINAGE GRADE P SUBSTATION ROCKSCHEDULE SCHEDULE I 3•ti e - > • n o ' sn 5ECURlTY PENCE FC,IRNN�D O1 COMPACTED CSBC ' e N SUBOR ADE SUBGRADE -CQNC FENCE _ WEED CONTROL-/ ;. COhC 1 6"}gyp£ ($p) 6"HDP£ (SP) CURB CURB e� PERF PIPE PERF PIPE FABRIC UNDER LSUBSTATION ROCK 4"SUBSTATION 1-09 W*CRUSHED DRAIN 2'-0" Tq o ROCK ROCK PER STATE SUBGRAAE 4 o SPEC 9-03.12(4) 3° CSBC w 1'-2'CSBC N TYP SUB-SUBGRADE LLF INTERCEPTOR INTERCEPTOR ROCK PERIMETER AREA W/12'I DEEP TRENCH SECTION C TRENCH SECTION D CURB AND SUBSTATION YARD SECTION E V.' 1' °" C5 1„- r_°, C5 TYPICAL PERIMETER AREA SECTION WITH 2' CURB DEPTH B ASPHALT FRAME AND GRATE m DRIVEWAY z io GENERAL NOTES (3)-04 BARS— cas(£cEiTwPo CONCRETE GROU7,TYP 1. CONCRETE INLETS SHALL CONFORM TO STATE STANDARD PLAN B-25.60-00. a _ INLET CATCH t�]N 2. TYPE 1 CATCH BASINS SHALL CONFORM TO STATE STANDARO PLAN 0-5.20-01, ci ° BASIN �v 3. pLL CCA CH BASTry AND CCOh'�ETE 1h�ET GRATES SHALL BE ECTANGULAR NERRIkGB0,4£ GRATES PER JIATE STANDARD PLAN B-30.90-�2. ,•° - 6" 6" E S 4. L 12"AND 24"MM)STME rr SEC7JONS SHALL HAVE AVERTED {� ANGULAR ik TYPES �d FRAMES PER STATE STAND& P CZ B-3 .10-01 PREC ST INTO E�T oo w� TYP ADJUSTMENT SECTION PER STATE $ A1.�PRD PLAN 8-30.90-02. _ e a e ,,yJOp �� gg pppy UI 7 p v1 5. CAST IN PLACE CONSCRETE PER STATE STANDARD PLAN P R�8 1N THEjCIIMEJER CURB RFPANSCO SAND rT PERIMETERM DRIVEWAY CURB T-TIF, o 1 TS PE T TE S7'ppARO AN F-3 . 03 1 SSEG y CSBC AND WEST SIDES TOTALLING AftOX 230 LF.REFER TO DRAWING S-4-05,AND 6"CSBC SECTION B & DETAIL ��ION THIS CD}R{AgWIINNG.g �}Ep� }{A 6. WATERSTOP GASKET H'tOT AS U GRNiXfr 1NSTALLEO A WATERTIGHT CONCRETE INLET CONCRETE PERIMETER CATCH BASIN CB3 SUB,yS(TAYIONINVERTED FRAME 90� L �G�1 CURB DETAIL 1 DETAIL 3 SUSORADE PRECAST INTO 24" d 44 " 1-0 34" a 1''°" C5 RECTANGULAR SECTION . W FINISHED CRATE 3W GRADE RNVERTEO FRAME COMPACTED ALTERNATE PRECAST INTO 24' SUBSTATION GRATE STRUCTURAL VERTICAL RECTANGULAR ROCK,TYP INVERTED FRAME e i BACKFILL I TRENCH �IONN "GRADE RECTAANNNGUL INTO 6" SNOHOMISH CIX1N7Y ` t SECTION ADJUSTMENT "--ALTERNATE SECTION CONCRETE •e 24"ADJUSTMENT i LAID-BACK SECTION p� n Vmm NSTfesCT N)1 !I TRENCH - INLE 8"HOPE (SP) O BEDDING ° 24"ADJUSTMENT a CATCH ORDER 100002342 MATERIAL SECTION 6"RECTANGULAR BASIN /r PIPE WATERSTOP ADJUSTMENT —s OPERATION GASKET A KET AND •° OA$K£T ANC SECTION 6" SCALE )VOTED GRO(KUTTTYP CONCRETE INLET GROUT,TYP _ MIN ,' '- - --WATERSTOP GASKET o — TYP e . e . ° 90 GROUT d I + 11' WATERTIGHT PVC 7 PIPE ADAPTER,TYP __ r OFTR OPA d FOUNOATIOy 6.7YPNE S 6„HOPE 6.,)IDF'E(�) 6"CSBC C34(RK i LEVEL TYP - EXISTING 4"CONDUIT TyP PE 1 6"HOPE(TYPE S) fNGR �. e a' •e (lE TBD) CATCH BASIN BEDDING NOTES: ( � 6„ TYPICAL CONCRETE INLET �+ �VD �uO 1. PROVIDE UNIFORM SUPPORT UNDER BARREL. MIN 6"CSBC CATCHAIL BASIN CB5, CB6, & CB7 _ DATE 5/4m 6"CSBC TYP e . '•e •e 2. HAND TAMP UNDER HAUNCHES. 3. CCOMPACT BEDDING AND BACKFILL MATERIAL TO 4a"= f`-0" EAST a 959 MAXIMUM DE ITY.EXCEPT BEDDING DIRECTLY -- C5 ARLINGTON $ ; OVER THE PIPE,N r,10 TAMP ONLY. CONCRETE INLET SWITCHING } 4. TRENCH WIDTH (W)= PIPE oo PLUS 24 STATION z CATCH BASIN C82 CATCH BASIN CB4 12 6 0 1 2 3 GRADINNG AND DRAINAGE X TYPICAL PIPE BEDDING G SECTION F DETAIL 2 DETAIL 4 V2" - 1'-O" SCALE IN FEET DETAILS A" SECTIONS Mrs �., e 1'_0" C5 'A"^ 1'-a" CS 12 6 0 1 2 3 L= 44" = l'-O" SCALE IN FEET 12 6 0 1 REV DRAWING $ 1" = 1'-0" SCALE IN FEET 0 S_4_G6 'a R/W LINE CSBC B" THICKNESS CSBC 8" THIM<SS R/W LINE CLASS V2-INCH HMA PAVEMENT. CSBC $"THICKNESS GATE SILL 4' MIN COMPACTED THICKNESS CLASS Vz-INCH F{IAA PAVEWENi. (2 LIFTS). 4' MIN COMPACTED THICKNESS GSTC 1V2" THIGKWSS (2 LIFTS). z EDRRIVEWAY APPROING GRAVEL ACH CSTC 1V2"THICKNESS a NG V2"R rr FINNIISHED IGRADE GATE SILL CONCRETE APPAY ROAC - ti 44 ftEBA.R,TYP COMPACTED SUBGRADE, +� NOTE 1 b"x 12"CONCRETE CURB - I PER STATE STANDARD PLAIDS 3"TYP.BOTH SIDES GRAVEL DRIVEWAY SECTION C COMPACTED SUBGRADE, F-IOA2-03 AND F-30.K1-03. 14TE F (W/2 HORIZONTAL •4 REBAR) COMPACTED SUBGRADE, NTS J NOTE 1 ASPHALT DRIVEWAY SECTION(5 ASPHALT DRIVEWAY SECTION B OQ NTS NTS CURVE } s3 z q' N 00 y Q's fOP rH cr r .00 g AVEL- GATE i 00 DRIVEWAY yA. c GRAVEL DRIVEWAY ^' GENERAL NOTES: cA�TE ,E v 2'-0"MAX ,n,\O O l I I 1. DENSE NAT VELS SHALL OOIL. 8E COMPACTED CSBC OR COVPACTEO 1p4 TRACER WIRE OR P o PAVED SURFACE DETECTOR TAPE (BLUE) /) .. ,�g9' 2. CONSTRUCT DRIVEWAY APPROACH PER CITY OF ARLIN'GTON - _ -^"Ir- \h CURVE e STANDARD DETAIL R-230. SUBGRADE ' b 02 3. EXTEND CONCRETE CURB ALONG THE BACK OF SIDEWALK TO THE '';W') E iE D C 40 PVC PIPE SLEEVE. G EPA@ OF THE DRIVEWAY TRANSITION PER S7Ati'DARD PLAN F-80.Y0-04, -' '•�'i>`�` X 9K1 s6 PH TYPE 1 DRIVEWAY ENTRANCE. N _,�s.V. ._Z;i: SLEEVE 2-FT MIN BEYOND CURB TAPPER TOP OF SOA zo N UNLESS OTHERWISE NOTED.SEAL BOTH O� o ENDSBACK WITH EXPANDING PLUGS PRIOR TO ______________��j / 1 T MATCH o0 .•,., h-�r - S"SD------------------------- EDGE OF PAVEMENT, 4. EACH OE TWO HORIZONTAL 44 REBM IN RE CONCRETE CURBUJG ON r i BACKFILlfNG. TYP o EACH SIDE OF THE ASPHALT PAVEMENT AREA AND SLOPE ASPWV.T PAVEMENT TOWARD C83 FOR PROPER DRAINAGE. G@ pp$ �iS. F, 3 5. THE NEW DRIVEWAY TOP OF PAVEMENT AID TOP Of GRAVEL Z CSBC BACKFILL C 1yA 87TH AVE NE e�2°A a ELEVATIONS SHALL MATCH GATE SELL AND BACK OF WALK `} cl a ELEVATIONS,OR EDGE OF 87TH ST NE PAVEMENT ELEVATIONS. UNDISTURBED SOIL CURVE DATA x 6. CONSTRUCT RR( ELEVATION OF C63 NO MORE THAN 11/4-M BELOW BACK OF WALK ELEVATION. IRRIGATION DESCRIPTION RADIUS ELT=eANGL TA�NT LENGTH o PIPE SLEEVE DETAIL 1 NORTH 24' GATE DRIVEWAY PLAN CURVE RETURN 02 1 12' 89'86'41" 12.03' 18.84' NTS (`,rj 1" 10' CURVE RETURN 83 v, Of"03,19" 11.98, 18.89' O L im i EAST 16' GATE DRIVEWAY PLAN o $ 1"a to'IRRIGATION ' i r ,�ISci3� g PIPE SLEEVE, GA f �. 00 :yr• pR,�� A �� G0 Gq E O CAE �ppo TYP 22.44'- t2.92' ' 1°j�O y9 •-----6"SD--------- ---- - --- ---- --- -_------ pG7- C84 1y0 51JOHOMISH COWFTY y =--------- --------' ------5"SO---- - b"50--' b"�'----- ---'� ,r---�-:--_6°SD_. y0 �n n --------159-------- - -----= L 1 �JF r-------- -- - -- GRAVEL o .........158 �rO FY(SSFB(CT A9 o ------- i EXST sy O sA DRIVEWAY 4 tOC o y000 R m A a[ *0002342' �� 15817 Soo o ASP ? v ^ NO �- �_ DRIYEIYAY gToO pG N - 'Ch91'3 ��-(5�-.. ..,r�9 TOG OPERA �l 1 V AY 'O ^' T10N 1- /� r.S NORTH �hQ c-•----------- I56, 5 i 80 7.30 CB2 .loam SCALE PJOTED o 60 O 60 o o op p e CURVE �9 /56. 15 4'j S L;O 119 CWR MIN 1 moo_ _160 tiy0 `rm c� S�(� y l yk e l T �iSpG OG %' T DFTR DPA 0C 7576 Li F6 ' 1P ENCR a � R CS- O EXST EXST'EXST p 1161-251 18" SD EXST EXST NOTE 2 EXST SIDEWALK T4 :NOTE 2 !SIDEWALK !TOTE 2 1D£WAYR 18"SD- SIDEWALK _ _ APVD '------ - G G qq �.. G7,a, - - 8.,S0 G G \ .. 12" SOa ' i iss �'� �O yq ,C81'.. DATE i ]8 212TH ST NE (TVEIT RD) AREAST LINGTON i SOUTH 20' GATE DRIVEWAY PLAN SOUTH 16' GATE DRIVEWAY PLAN CURVE DATA SSTATIONG s 1 10 RADIUS LTA ANGLE] TANGENT LENGTH CALL 48 HOURS DRIVEWAY PLANS " DESCRIPTION RADIUS (6) (T) (L) BEFORE YOU DIG AND SECTIONS 1-800-424-5555 CURVE RETURN r1 1S' 39.30'44" 1 5.39' 10.34' Is l= E SOUTH 24' GATE DRIVEWAY PLAN 10 5 0 to REY DRAWINGah } � 1„o 1" = 10' SCALE IN FEET S-.4_C GENERAL NOTES: 1 WARNING IDENTIFICATION UkNI�OS6Y THERDISTRICTT,, AND SHALL BE INSTALLED BY THE CONTRACTOR, 2. BOLT SUBSTATION IDENTIFICATION SIGNS TO THE DRIVE y GATE AT THE LOCATION SHOWN.REFER TO DRAWING S-4-Ci2. 3. INSTALL "HAZARDOUS VOLTAGE""KEEP OUT"WARNING SIGNS a 0+7 THE OUTSIDE OF THE SUBSTgT1414 SECURITY FENCES. INSTALL BOTTOM OF SIGNS AT 4-6 ABOVE THE BOTTOM s OF THE FENCE,AT THE DIDDLE OF INDIVIDUAL FENCE f ` y SECTI03+S,AT THE LOCATIONS SHOWN. ma O(L DRILL HOLES AT CENTERLINE OF SIGN AT 12-INCH HORIZONTAL x NAVY AREA 51 YARD 06 vw SPACING TO ALIGN WITH CENTER OF FENCE PALES.FASTEN wz TO PALES WITH TWO -INCH DIAMETER STAIP+LESS STEEL wai N VA-INCH INCLUDING TWO WASHERS AND ONE NUT WITH EACH BOLT. R OF FENCE POST 253.74' ?o oa NORTH BOLTS TEVERY BOLT ONES NOTI PROJECT LENGTH THREE H f FULL THREADS AND NO MORE THAN 34-ICCH BEYOND THE NUT 139.12' 1 4.61' 1` �OF FENCE POST WHEN ASSEMBLED. f 4. WHERE FENCE RAILS ATTACH TO GATE POSTS,TACK WELD 51.63' 3 SECTIONS 24.67' MOUNTING SCREWS TO THE RAIL BRACKET. GEXST FENCE POST 4.33 DRIVE GATE or F `D � ` �O ti� EXST FENCE AND CURB,TYP EXST FENCE POST OG > 4 24' S. WHERE GATE LATCHES AND DROP BARS ARE BOLTED TO flW POST l:h'' o� hoy�'1 9Oc+ CH1 GATE GATE FRAMES,TACK WELD THE NUT TO THE MOUNTING BOLT. -�' --� x x x z __ _ ' •O� 1 6. FIELD LOCATE EACH GATE KEEPER TO MATCH SPECIFIC GATE dF QQ FENxCEPOST gg LEAF SWIPNG AND CENTERED 2-FEET INSIDE FENCE. r OF FE E POST GG G6� z 3 {Sg/aC 1`\6G./ 0 3 OF FENCE OQPWR o o POST (n� / 1 s£cnD++ �p�� Q KEY NOTES a Z py �� y 159 o A O1 SCREW PALE 70 CORNER POST. a/TSID 3 I 4 4 t� GRATE C10 4�11 3 O INSTALL RiLLOCATION TE KEEPER.FIELD LOCATE BASED ON DROP 9 OF Ft?I P0S SaC r o�` y0 16g.5 �+OUTSIDE CORNER t59.17 6, Osp TYP OF FENCE POST .i I C11 LEGEND: f rn ® GATE KEEPER � r m 3 f v z r « f U� E-W f P pr4o BASELINE - -—-—-—-—-—- .-------._....------ ---------------------- � 00 z r 3 O 33 F f O 3 cn p p E D Lu i E r f 3 20 2 16' r i SUBSTATION 4 24- �n N n 3 C50 DRIVE C10 DRIVE C10 DETAIL Ci0 IVE x� GATE GATE o^ GATE Qz G pG^ �o Opp fr S SEC7IOP AGE p�' >�o D+iTSIDE CORNER CRAL ®,`p 4 .� {sue p +�y, { y A s�p OF FEOUTSIDE NCE POST ® ® K ® F Of OF FENCEPO CORNER >3. !3, >, pOp„ SI.'OHO'Idn15I HlnC(OIRJTY 1 �p0, �On� 10�^ 's'Oo," i SECTION UaLzo.50' 6 SECTIONS - 48.50' J.16.50 11 SECTIONS - 88.42' °y 24. 7'0 3 SECt -S 1 Op TSrpF IVE GA IVE GA E DRIVE ATE 24tiC�00p s��c UtAI1Y AS1fGC1 No 1 349.51' 81.60' AOSTR ORDER *0002342 ,Y w� 4.48' S 5.50 zy OPERATION o WILKIN CID pa �Ld GATE O SCALE NOTED ,jU W pZ pZ F4a rN4 DFTR BR/DPA pp 00 C+G(R OM}{ ENGR FENCE PLAN 'PV° f.= 20' DATE S t 15S EAST ARLINGTON SWITCHING STATION Y FE1+CE PLAN 1, CALL 48 IioURS 20 10 0 20 3 BEFORE YOU DIG REV I DRAWING g 1-800-424-5555 1-- 20 SCALE IN FEET No 0 1 S-4-C9 j FENCING MATERIAL SCHEDULE TOP VIEW TOP VIEW LINE DESCRIPTION SIZE MAN VNSU ER ITE20'-6" 1 GAA(TLET STYLE PALE 244"x 44"x 14 GAUGE 1 8'-O"±Vz" 2 IMPASSE II RAIL WITH HOLES 2"x 2"x 11 GAUGE RIN.B-8 Cil j 9'ZYP" 3Vi" (LATCH CLEARANCE) ' 3 LINE POST-1-SCAM i 1 4"x 230"x 1]GAUGE 3P$3XXX-41 1 , f 6b2Vi�EMfCE 4 CORNER POST-I-BEAN 4"x 244"x H GAUGE 3PB3XXX-41 POST CAP, 5 GATE POST-WALK GATE v a 7 TYP - '? STEEL 4"SQUARE x 11 GAUGE TUBE PB40XXX - I 6 GATE POST-DRIVE GATE 06-WIDE) 6"SQUARE x 35d'THICK TUBE P660XXX RAIL - N 1 7 GATE POST-DRIVE GATE (20-WIDE) 6"SQUARE x 4W THICK TUBE P860XXX f 8 GATE POST-DRIVE GATE (24-WIDE) 8"SQUARE x t/<"THICK TUBE Pe80XXX ' 3 - r SCREW POST TYP 8 SWING GATE FRAME 2 0 � 2"SQUARE x 11 GAUGE TUBE FABRICATE f le-b RB ! 11 11 ADJUSTABLE TRUSS ROD ASSEMBLY49"DIA 12 DRIVE GATE-HEAVY INDUSTRIAL ADJUSTABLE 180°HINGEWH180 13 WALK GATE-BOX HINGE )PU517 I � � E4 DRIVE GATE-INDUSTRIAL DOUBLE DRIVE LATE LATCH DRB200 FENCE FFE)NNCE 3" iv FENCE $5 WALK GATE-STRONG ARM SINGLE GATE LATCH 058]00 0 o ,,, =0 i6 DROP BAR ANCHOR N35740 $ L6 17 GATE CENTER STOP Vz"EXPANSION MASTER HALCO 015911 s 3y< iii C11 i i I I I TYPICAL i i JOINT,TYP 18 CORNER BRACKET BX609 6"O,C. TYPICAL a� , MOUNTED 6110.0. TO END OF u� u� �--� GATE FROF � SILL GATE i i 19 BOLLARD RAIL BRACKET BX606 "' iii 2'-0"0 x 3'-0" T7 MOUNTED TO ' ' 20 FLAT STRAP BRACKET CONC FOOTING, 0 BACKSIDE OF ' ' F BX022 f`^4"6 x 3'-0" Ct} EXTEND OF CN TO DRIVE GATE FRAME Cit 21 ATTACKVE14T FITTINGS AND MISC HAROWARE VARIOUS AVERISTAR CONC FOOTING, FOOTING,TYP GATE SILL FULLLhDEPTH OF 22 ? 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I FENCE 24' DRIVE GATE WAND 20' DRIVE I I I I CURB SECTION B SILL SECTION C GATE SILL SECTION D 1 I IVz'= 1'-0" C10 IV2„= 1._0,� C10 Ive" 1'-0" C10 II I I I 1 1 I I I I 1 1 I I I I m TYPICAL FENCE WALK GATE DRIVE GATE SECTION A SECTION E SECTION F r-o" C10 Y m m b � UN � )-a 2 zo pi3AR `�r 00 SQUARE S GATE ATE E 4 4 POST f POST 33 / 0- BOLTI •� � ' LORNER 9 GATE FRAME P BRACKET A POST CAP—+/l GUIDE, J TY _ Ii i E ti 18 OLT L 14 SECURITY 0 0 CKET hY17,7YP T ol TOP VIEW C 3 q REETTENTION BOLL r to s3>a3 TYP DROP BAR, SECURITY FASTENER O BOLLARD RAIL DRIVE GATE SELL FENCE ASSEMBLY DETAIL 1 BRACKET CORNER ET AI R 2 BRACKET DETAIL 3 0 SNOHOM[SH COUNTY NTS C10 NTS NTS CENTER STOP �� f1kiX U10.RY DISIRICt M]I ORDER 100002342 i PALE yr�pr'9ji OPERATION DRIVE GATE r I-BEAM POST DROP BAR SCALE NOTED II RAIL (ISOMETRIC) DETAIL E DFTR DPA 20 1 z m{°RADIUS EocE NOTE NTS C40 CWR DMH r; 3 r O i 0 0 GRAD D 1. PALES NOT SHOWN FOR CLARITY. E((GR '1 RM j 6„ 4' BELOW TOC RIP TUBE ' /WVD SNp .-1 KEY NOTES: DATE S i CUT RAIL TO LENGTH. F O" 6 E ;i FOOTING NG 1�-b` DEEP r; 02 DRILL W! HOLE. (TUBE FORM) EAST 12 s o 1 z 3 EAST s Q3 BOLT RAIL TO I-BEAM POST i W/SUPPLIED FASTENERS. Vz" = f-O" SCALE IN FEET SWITCHING 9 CUT RAIL STATION to INSTALLATION 12 6 D 1 FENCE DETAILS y DETAIL 4 GATE KEEPER DETAIL 5 1"_ ,'-o" SCALE IN FEET NTS tz 9 6 3 0 1 1 Vz" = 1'-0" SCALE IP( FEET REV DRAWING 0 S-4—C11 Stormwater Pollution Prevention Plan For East Arlington Switching Station Owner Snohomish County PUD No. 1 P.O. Box 1107 Everett, WA, 98206-1107 Project Site Location 21210 87`h Ave NE Arlington, WA 98203 SWPPP Prepared By Snohomish County PUD No. 1 P.O. Box 1107 Everett, WA (425)-783-5022 Tom Hendricks, PE SWPPP Preparation Date 5/16/2018 Approximate Project Construction Dates July 2018 Through November 2018 4� A� D 3M Contents 1.0 Introduction 1 2.0 Site Description 3 2.1 Existing Conditions 3 2.2 Proposed Construction Activities 4 3.0 Construction Stormwater BMPs 6 3.1 The 12 BMP Elements 6 3.1.1 Element#1 —Mark Clearing Limits 6 3.1.2 Element#2—Establish Construction Access 6 3.1.3 Element#3 —Control Flow Rates 7 3.1.4 Element#4—Install Sediment Controls 7 3.1.5 Element#5 —Stabilize Soils 8 3.1.6 Element#6—Protect Slopes 9 3.1.7 Element#7—Protect Drain Inlets 9 3.1.8 Element#8—Stabilize Channels and Outlets 10 3.1.9 Element#9—Control Pollutants 10 3.1.10 Element#10—Control Dewatering 11 3.1.11 Element#11 —Maintain BMPs 12 3.1.12 Element#12—Manage the Project 12 3.2 Site Specific BMPs 14 4.0 Construction Phasing and BMP Implementation 15 5.0 Pollution Prevention Team 16 5.1 Roles and Responsibilities 16 5.2 Team Members 16 6.0 Site Inspections and Monitoring 17 6.1 Site Inspection 17 6.1.1 Site Inspection Frequency 17 6.1.2 Site Inspection Documentation 17 6.2 Stormwater Quality Monitoring 18 6.2.1 Turbidity 18 6.2.2 pH Sampling 19 7.0 Reporting and Recordkeeping 20 7.1 Recordkeeping 20 7.1.1 Site Log Book 20 7.1.2 Records Retention 20 7.1.3 Access to Plans and Records 20 ii 7.1.4 Updating the SWPPP 20 7.2 Reporting 21 7.2.1 Discharge Monitoring Reports 21 7.2.2 Notification of Noncompliance 21 7.2.3 Permit Application and Changes 21 Appendix A Site plans—Refer to Contract Drawings Appendix B Construction BMPs Appendix C Alternative Construction BMP list Appendix D General Permit Appendix E Site Log and Inspection Forms iii Stormwater Pollution Prevention Plan 1.0 Introduction This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the NPDES stormwater permit requirements for the East Arlington Switching Station project located at 21210 87th Ave NE, Arlington. The existing substation property lies to the northwest of the intersection of 212th St NE and 87th Ave NE. The construction site is a 1.25-acre portion of a 1.66 acre parcel that currently contains the East Arlington Substation. The proposed development consists of the removal of the existing out dated 115kV and 12kV substation and replacement with a new six-breaker ring bus 115kV switching station. Construction activities will include installing TESC measures, demolition of the existing substation improvements, excavation, grading, installation of drainage features, construction of foundations and slabs for the new equipment, installation of underground conduit and vaults, constructing a grounding system, installing a new security fence with high voltage warning signs, one paved main driveway and four maintenance access gravel driveways, landscaping, and an irrigation system. The purpose of this SWPPP is to describe the proposed construction activities and all temporary and permanent erosion and sediment control (TESC) measures, pollution prevention measures, and inspection activities that will be implemented during the proposed construction project. The objectives of the SWPPP are to: 1. Implement Best Management Practices (BMPs) to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. Prevent violations of surface water quality, ground water quality, or sediment management standards. 3. Prevent, during the construction phase, adverse water quality impacts including impacts on beneficial uses of the receiving water by controlling peak flow rates and volumes of stormwater runoff at the Permittee's outfalls and downstream of the outfalls. This SWPPP was prepared using the Ecology SWPPP Template downloaded from the Ecology website on March 29, 2018. This SWPPP was prepared based on the requirements set forth in the Construction Stormwater General Permit,Stormwater Management Manual for Western Washington (SWMMWW 2012/14). The report is divided into seven main sections with several appendices that include stormwater related reference materials. The topics presented in each of the main sections are: ■ Section 1— INTRODUCTION. This section provides a summary description of the project, and the organization of the SWPPP document. 1 Stormwater Pollution Prevention Plan ■ Section 2—SITE DESCRIPTION. This section provides a detailed description of the existing site conditions, proposed construction activities, and calculated stormwater flow rates for existing conditions and post—construction conditions. ■ Section 3—CONSTRUCTION BMPs. This section provides a detailed description of the BMPs to be implemented based on the 12 required elements of the SWPPP. ■ Section 4—CONSTRUCTION PHASING AND BMP IMPLEMENTATION. This section provides a description of the timing of the BMP implementation in relation to the project schedule. ■ Section 5— POLLUTION PREVENTION TEAM. This section identifies the appropriate contact names (emergency and non-emergency), monitoring personnel, and the onsite temporary erosion and sedimentation control inspector ■ Section 6— INSPECTION AND MONITORING. This section provides a description of the inspection and monitoring requirements such as the parameters of concern to be monitored, sample locations, sample frequencies, and sampling methods for all stormwater discharge locations from the site. ■ Section 7— RECORDKEEPING. This section describes the requirements for documentation of the BMP implementation, site inspections, monitoring results, and changes to the implementation of certain BMPs due to site factors experienced during construction. 2 Stormwater Pollution Prevention Plan 2.0 Site Description 2.1 Existing Conditions The existing substation site is located 21210 87th Avenue NE in the City of Arlington, WA 98223. Eagle Creek lies to the east with buffers that extend onto the site. The existing substation site is generally flat with any upstream runoff bypassing the site in a grass-lined swale to the west of the existing substation fence and flowing into an 18-inch CMP near the southwest substation fence corner that turns eastward and extends along the north side of 2121h St NE to a city catch basin at the intersection of 212th St NE and 87th Ave NE eventually discharging into Eagle Creek. Currently any stormwater inside the substation yard that doesn't infiltrate into the substation gravel and native subgrade is gathered in perforated pipe underneath the cable trench and is collected in an oil separator basin near the southeast corner of the site, which discharges through an oil trap to the previously mentioned city catch basin at the intersection of 212th St NE and 87th Ave NE. The eastern 75% of the property contains the developed electrical substation site and the western 25% is covered with native shrubs and emergent species. Along the south and east substation security fence a single row of arborvitae trees exists for visual screening purposes. Grades in the existing substation yard generally descend from northwest to southeast with the local high elevation of 162 feet in a small area of the northwest corner of the existing yard and the low of 156 feet in the southeast corner of the property outside the fence. Three wetlands exist in fairly close proximity with buffers that extend onto the substation site. Refer to The Critical Area Determination Report for Snohomish County PUD No. 1 East Arlington and Eagle Creek Substations prepared by Wetland Resources, Inc. dated July 2016 and revised on January 25, 2017 Zipper Geo Associates, LLC has prepared a geotechnical report for the site titled Geotechnical Engineering Report, Proposed Eagle Creek Substation dated September 15, 2016. With the exception of the northwest corner, the entire yard is surfaced with coarse gravel-size crushed rock. Surfacing in the northwest corner consists of gravelly sand and quarry spalls. The thickness of the fill varied across the yard from about 2 feet to 7.5 feet in depth with characteristics varying from medium dense silty gravel to medium dense to very dense gravelly sand. Native soils observed below the surficial fill material generally consisted of medium dense to very dense silty sand with variable gravel content. The US Department of Agriculture's Soil Survey of Snohomish County Area Washington has the on-site soils mapped mostly as Everett very b gravelly sandy loam, with 0 to 8 percent slopes. The 2016 geotechnical report states the Geologic Map of the Arlington East Quadrangle, Snohomish County, Washington describes the site as underlain by the Marysville Sand member of recessional outwash deposits. However, based upon the condition disclosed by the boring completed on the site, it appears that the native soils are more representative of the glacial till which has been mapped to the southeast and northwest of the site and underlies the recessional deposits. 3 Stormwater Pollution Prevention Plan 2.2 Proposed Construction Activities This project involves the demolition of the existing PUD East Arlington Substation and the reconstruction of a new six breaker 115 kV ring bus switching station. The entire existing substation site will be redeveloped with new foundations and equipment including a new fence with enhanced maintenance access from 212th St NE and from 87th Ave NE. Construction activities will include installing TESC measures; demolition of existing concrete foundations & slabs, conduit& conductor, cable trench, grounding system, and security fence except the common fence with the Navy's Area 51 yard. Removal of unsuitable soils; regrading the site and excavation of trenches and foundations; installing new conduit, foundations, slabs, a stormwater interceptor trench, electrical vaults, security fence, and gravel & asphalt driveways. Upstream runoff currently bypasses the substation site in a grass-lined swale to the west of the existing substation fence and enters an 18" CMP near the southwest substation fence corner that turns and extends eastward along the north side of 212th St NE to a city catch basin at the intersection with 87th Ave NE which discharges eastward through a 12 inch CPP into Eagle Creek. This existing bypass condition is outside the proposed construction area and will remain unchanged after the proposed development. For the substation redevelopment the site runoff is intended to be infiltrated through the substation gravel or into the landscaping areas. Precipitation falling within the substation yard will infiltrate through the imported crushed rock fill layer and then at a relatively slower rate will infiltrate into the native soil below. The imported crushed rock base and interceptor trench will act as a reservoir, retaining water during intense rainfall events. Water runoff from landscaped areas will drain naturally. The following summarizes details regarding site areas: • Total existing developed substation area: 1.25 acres • Percent impervious area before construction: 23.67% • Percent impervious area after construction: 8.07% • Disturbed area during construction: 1.25 acres • Disturbed area that is characterized as impervious (i.e., access roads, staging,parking): 0.2959 acres • 2-year stormwater runoff peak flow prior to construction(existing): 0.181 cfs • 10-year stormwater runoff peak flow prior to construction(existing): 0.324 cfs • 2-year stormwater runoff peak flow during construction: 0.025 cfs • 10-year stormwater runoff peak flow during construction: 0.045 cfs • 2-year stormwater runoff peak flow after construction: 0.025 cfs • 10-year stormwater runoff peak flow after construction: 0.045 cfs 4 Stormwater Pollution Prevention Plan Peak flow values were calculated using the WWHM12 software. Refer to the Full Drainage Report for the calculations. No temporary/permanent TESC or flow control BMP's are proposed that require flow rate based engineering calculation. After the imported substation gravel in the substation yard and gravel perimeter is graded to final top of rock elevation, the gravel driveways are graded to final elevation, and the asphalt pavement for the main driveway is placed; the landscaping and irrigation system will be installed to stabilize the site. Should any unexpected contaminated soils be uncovered the District's Environmental Affairs department will be contacted and proper cleanup measures will be implemented. Any ground water encountered will be dealt with appropriately and the method will be selected by the site contractor. The method could be pumping the groundwater into a Baker tank and either hauling contaminated water to an offsite disposal site or metering the uncontaminated discharge into existing native vegetation and grassy areas onsite. 5 Stormwater Pollution Prevention Plan 3.0 Construction Stormwater BMPs 3.1 The 12 BMP Elements 3.1.1 Element#1 —Mark Clearing Limits To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. Trees that are to be preserved, as well as all sensitive areas and their buffers, shall be clearly delineated,both in the field and on the plans. In general, natural vegetation and native topsoil shall be retained in an undisturbed state to the maximum extent possible. The BMPs relevant to marking the clearing limits that will be applied for this project include: • Preserving Natural Vegetation (BMP C 101) • High Visibility Plastic or Metal Fence (BMP C 103) High visibility fence will be staked along property lines where property line fencing does not exist as well as around vegetated areas to be preserved. Preserved areas will provide stormwater filtration, and reduce runoff velocity. Alternate BMPs for marking clearing limits are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.2 Element#2—Establish Construction Access Construction access or activities occurring on unpaved areas shall be minimized, yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads, and wheel washing, street sweeping, and street cleaning shall be employed to prevent sediment from entering state waters. All wash wastewater shall be controlled on site. The specific BMPs related to establishing construction access that will be used on this project include: • Stabilized Construction Entrance (BMP C 105) • Construction Road/Parking Area Stabilization(BMP C 107) The existing two gravel driveways will be utilized as the project site's stabilized construction entrances. The existing gravel area in the southeast corner of the property will provide a suitable parking area for construction traffic. A secondary parking area will be north of the existing substation in the gravel area east of the Navy's Area 51 yard. Alternate construction access BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate 6 Stormwater Pollution Prevention Plan during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.3 Element#3—Control Flow Rates In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site shall be controlled. Any stormwater collected will be directed to a collection point along the west side of the construction site and dispersed through a silt bag into the natural vegetation which covers the west 25% of the substation property. Dispersed stormwater will sheet flow over the preserved vegetated areas and surface infiltrate. Flow control will be provided via infiltration and attenuation. The project will ultimately reduce the impervious surface area on-site and enhance the landscaping surface area. An increase in stormwater runoff velocity and peak flow rates are not expected as a result of the proposed construction activity. Dispersion and infiltration BMP's shall be used to contain stormwater on-site. Alternate flow control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. In general, discharge rates of stormwater from the site will be controlled where increases in impervious area or soil compaction during construction could lead to downstream erosion, or where necessary to meet local agency stormwater discharge requirements (e.g. discharge to combined sewer systems). 3.1.4 Element#4—Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharged to an infiltration facility. The specific BMPs to be used for controlling sediment on this project include: • Storm Drain Inlet Protection(BMP C220) • Silt Fence (BMP C233) • Straw Wattles (BMP C235) 7 Stormwater Pollution Prevention Plan The preserved natural vegetation to the west of the disturbance will provide stormwater filtration, and reduce any runoff velocity. Storm drain inlet protection will be installed in all proposed catch basins susceptible to sediment loading. Silt fencing will be installed along the west side of the construction area to prevent any sediment laden water from discharging into the grassy swale along the west side that directs any flow to the 18-inch CMP. Straw wattles would be an alternate sediment control BMP placed in the grassy swale to control any potential flow in the grassy swale. Alternate sediment control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. In addition, sediment will be removed from paved areas in and adjacent to construction work areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on vehicle tires away from the site and to minimize wash off of sediments from adjacent streets in runoff. In some cases, sediment discharge in concentrated runoff can be controlled using permanent stormwater BMPs (e.g., infiltration swales, ponds, trenches). Sediment loads can limit the effectiveness of some permanent stormwater BMPs, such as those used for infiltration or biofiltration; however, those BMPs designed to remove solids by settling(wet ponds or detention ponds) can be used during the construction phase. When permanent stormwater BMPs will be used to control sediment discharge during construction, the structure will be protected from excessive sedimentation with adequate erosion and sediment control BMPs. Any accumulated sediment shall be removed after construction is complete and the permanent stormwater BMP will be restabilized with vegetation per applicable design requirements once the remainder of the site has been stabilized. 3.1.5 Element#5—Stabilize Soils Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. The specific BMPs for soil stabilization that shall be used on this project include: • Temporary and Permanent Seeding(BMP C 120) • Plastic Covering(BMP C123) • Topsoiling(BMP C 125) • Surface Roughening (BMP C130) • Dust Control (BMP C 140) • Early application of gravel base on areas to be graveled. 8 Stormwater Pollution Prevention Plan Alternate soil stabilization BMPs are included in Appendix C as a quick reference tool for the on-site inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction. The Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, no soils shall remain exposed and unworked for more than 7 days during the dry season(May 1 to September 30) and 2 days during the wet season(October 1 to April 30). Regardless of the time of year, all soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on weather forecasts. In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion, protected with sediment trapping measures, and where possible,be located away from storm drain inlets, waterways, and drainage channels. 3.1.6 Element#6—Protect Slopes All cut and fill slopes will be designed, constructed, and protected in a manner that minimizes erosion. The following specific BMPs will be used to protect slopes for this project: • Temporary and Permanent Seeding(BMP C 120) • Straw Wattle (BMP C235) Alternate slope protection BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.7 Element#7—Protect Drain Inlets Two storm drain inlets exist near the site that could potentially receive surface runoff from the construction site. One is at the corner of 2121h St NE and 87th Ave NE and the other is approximately 240 feet west along the north side of 212th St NE. Also the 18" CMP inlet near the southwest fence corner could potentially receive surface runoff from the construction site since the grassy swale along the west side of the construction site flows directly into this culvert. The grassy swale should be dry during the timeframe of this construction,but a rain event could change these dry conditions and create flow that would enter the culvert and City's storm water drainage system. All storm drain inlets and culverts made operable during construction shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. However, the first priority is to keep all access roads clean of sediment and keep street wash water separate 9 Stormwater Pollution Prevention Plan from entering storm drains until treatment can be provided. Storm Drain Inlet Protection(BMP C220)will be implemented for all drainage inlets and culverts that could potentially be impacted by sediment-laden runoff on and near the project site. The following inlet protection measures will be applied on this project: • Storm Drain Inlet Protection(BMP C220) If the BMP options listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D), or if no BMPs are listed above but deemed necessary during construction, the Certified Erosion and Sediment Control Lead shall implement one or more of the alternative BMP inlet protection options listed in Appendix C. 3.1.8 Element#8—Stabilize Channels and Outlets Where site runoff is to be conveyed in channels efforts will be taken to prevent downstream erosion. The specific BMPs for channel and outlet stabilization that shall be used on this project include: • Grass-Lined Swales (BMP C201) • Outlet Protection (BMP C209) There are no channels or direct discharge to a stream for this project. A natural grass swale does exist west of the construction area. This grassy swale shall be utilized to intercept any surface water runoff that may flow out of the natural vegetation area covering the west 25% of the of the substation property as a result of dewatering the construction site. The outlet of any pipe discharge shall be protected to prevent scouring and downstream erosion. Alternate channel and outlet stabilization BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.9 Element#9—Control Pollutants All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well-organized, and free of debris. If required, BMPs to be implemented to control specific sources of pollutants are discussed below. 10 Stormwater Pollution Prevention Plan Vehicles, construction equipment, and/or petroleum product storage/dispensing: ■ All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. ■ On-site fueling tanks and petroleum product storage containers shall include secondary containment. ■ Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. ■ In order to perform emergency repairs on site, temporary plastic will be placed beneath and, if raining, over the vehicle. ■ Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Chemical storage: ■ Any chemicals stored in the construction areas will conform to the appropriate source control BMPs listed in Volume IV of the Ecology stormwater manual. In Western WA, all chemicals shall have cover, containment, and protection provided on site,per BMP C 153 for Material Delivery, Storage and Containment. Demolition: ■ Dust released from demolished sidewalks, structures, or foundations will be controlled using Dust Control measures (BMP C 140). ■ Storm drain inlets vulnerable to stormwater discharge carrying dust, soil, or debris will be protected using Storm Drain Inlet Protection (BMP C 152) ■ Process water and slurry resulting from sawcutting and surfacing operations will be prevented from entering the waters of the State by implementing Sawcutting and Surfacing Pollution Prevention measures (BMP C 152). Concrete and grout: ■ Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures (BMP C 151). Ultimately, a Spill Prevention, Control, and Countermeasure (SPCC) Plan under the Federal regulations of the Clean Water Act(CWA) will be required for the substation once operational. 3.1.10 Element#10—Control Dewatering All dewatering water from open cut excavation, tunneling, foundation work, trench, or underground vaults shall be discharged into a controlled conveyance system prior to discharge to 11 Stormwater Pollution Prevention Plan a sediment trap or sediment pond. Any channels will be stabilized, per Element#8. Clean, non- turbid dewatering water will not be routed through stormwater sediment ponds, and will be discharged to systems tributary to the receiving waters of the State in a manner that does not cause erosion, flooding, or a violation of State water quality standards in the receiving water. Highly turbid dewatering water from soils known or suspected to be contaminated, or from use of construction equipment, will require additional monitoring and treatment as required for the specific pollutants based on the receiving waters into which the discharge is occurring. Such monitoring is the responsibility of the contractor. However, the dewatering of soils known to be free of contamination will trigger BMPs to trap sediment and reduce turbidity. At a minimum, geotextile fabric socks/bags/cells will be used to filter this material. Other BMPs to be used for sediment trapping and turbidity reduction include the following: • Concrete Handling(BMP C151) • Use of a sedimentation bag, with outfall to vegetated area for small volumes of localized dewatering. 3.1.11 Element#11 —Maintain BMPs All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMPs specifications. Visual monitoring of the BMPs will be conducted at least once every calendar week and within 24 hours of any rainfall event that causes a discharge from the site. If the site becomes inactive, and is temporarily stabilized, the inspection frequency will be reduced to once every month. All temporary erosion and sediment control BMPs shall be removed within 30 days after the final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil resulting from removal of BMPs or vegetation shall be permanently stabilized. 3.1.12 Element#12—Manage the Project Erosion and sediment control BMPs for this project have been designed based on the following principles: ■ Design the project to fit the existing topography, soils, and drainage patterns. ■ Emphasize erosion control rather than sediment control. ■ Minimize the extent and duration of the area exposed. ■ Keep runoff velocities low. ■ Retain sediment on site. ■ Thoroughly monitor site and maintain all ESC measures. ■ Schedule major earthwork during the dry season. 12 Stormwater Pollution Prevention Plan In addition,project management will incorporate the key components listed below: As this project site is located west of the Cascade Mountain Crest, the project will be managed according to the following key project components: Phasing of Construction ■ The construction project is being phased to the extent practicable in order to prevent soil erosion, and, to the maximum extent possible, the transport of sediment from the site during construction. ■ Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of the clearing activities during each phase of construction, per the Scheduling BMP (C162). Seasonal Work Limitations ■ From October 1 through April 30, clearing, grading, and other soil disturbing activities shall only be permitted if shown to the satisfaction of the local permitting authority that silt-laden runoff will be prevented from leaving the site through a combination of the following: ❑ Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters; and ❑ Limitations on activities and the extent of disturbed areas; and ❑ Proposed erosion and sediment control measures. ■ Based on the information provided and/or local weather conditions, the local permitting authority may expand or restrict the seasonal limitation on site disturbance. ■ The following activities are exempt from the seasonal clearing and grading limitations: ❑ Routine maintenance and necessary repair of erosion and sediment control BMPs; ❑ Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil; and ❑ Activities where there is 100 percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. Coordination with Utilities and Other Jurisdictions ■ Care has been taken to coordinate with utilities, other construction projects, and the local jurisdiction in preparing this SWPPP and scheduling the construction work. 13 Stormwater Pollution Prevention Plan Inspection and Monitoring ■ All BMPs shall be inspected, maintained, and repaired as needed to assure continued performance of their intended function. Site inspections shall be conducted by a person who is knowledgeable in the principles and practices of erosion and sediment control. This person has the necessary skills to: ❑ Assess the site conditions and construction activities that could impact the quality of stormwater, and ❑ Assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. ■ A Certified Erosion and Sediment Control Lead shall be on-site or on-call at all times. ■ Whenever inspection and/or monitoring reveals that the BMPs identified in this SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP ■ This SWPPP shall be retained on-site or within reasonable access to the site. ■ The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. ■ The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven (7) days following the inspection. 3.2 Site Specific BMPs Site specific BMPs are shown on the TESC Plan Sheets and Details in Appendix A. These site specific plan sheets will be updated annually. 14 Stormwater Pollution Prevention Plan 4.0 Construction Phasing and BMP Implementation The BMP implementation schedule will be driven by the construction schedule. The following provides a sequential list of the proposed construction schedule milestones and the corresponding BMP implementation schedule. The list contains key milestones such as wet season construction. The BMP implementation schedule listed below is keyed to proposed phases of the construction project, and reflects differences in BMP installations and inspections that relate to wet season construction. The project site is located west of the Cascade Mountain Crest. As such, the dry season is considered to be from May 1 to September 30 and the wet season is considered to be from October 1 to April 30. ■ Estimate of Construction start date: 07/16/18 ■ Estimate of Construction finish date: 11/09/18 ■ Mobilize equipment on site: 07/16/18 ■ Mobilize and store all ESC and soil stabilization products (store materials on hand BMP C150): 07/17/18 ■ Mark the limits of site disturbance: 07/17/18 ■ Install silt fencing and storm drain inlet protection: 07/17/18 ■ Start demolition phase: 07/18/18 ■ Start site grading & excavation: 07/30/18 ■ Install interceptor trench and CB's: 08/06/18 ■ Site inspections and monitoring conducted weekly and for applicable rain events as detailed in Section 6 of this SWPPP: 08/06/18 ■ Implement soil stabilization and sediment control BMPs during earthwork activities: 08/06/18 ■ Start grounding well installation: 08/06/18 ■ Start drilled pier installation: 08/13/18 ■ Begin conduit, vaults, and foundation installation: 08/20/18 ■ Wet Season starts: 10/01/18 ■ Start Installation of irrigation and landscaping: 10/01/18 ■ Complete site work: 11/08/18 ■ Remove remaining TESC facilities 11/09/18 ■ Construction Complete 11/09/18 15 Stormwater Pollution Prevention Plan 5.0 Pollution Prevention Team 5.1 Roles and Responsibilities The pollution prevention team consists of personnel responsible for implementation of the SWPPP, including the following: ■ Certified Erosion and Sediment Control Lead(CESCL)—primary contractor contact, responsible for site inspections (BMPs, visual monitoring, sampling, etc.); to be called upon in case of failure of any ESC measures. ■ Resident Engineer—For projects with engineered structures only (sediment ponds/traps, sand filters, etc.): site representative for the owner that is the project's supervising engineer responsible for inspections and issuing instructions and drawings to the contractor's site supervisor or representative. ■ Emergency Ecology Contact—individual to be contacted at Ecology in case of emergency. ■ Emergency Owner Contact—individual that is the site owner or representative of the site owner to be contacted in the case of an emergency. ■ Non-Emergency Ecology Contact—individual that is the site owner or representative of the site owner than can be contacted if required. ■ Monitoring Personnel—personnel responsible for conducting water quality monitoring; for most sites this person is also the Certified Erosion and Sediment Control Lead. 5.2 Team Members Names and contact information for those identified as members of the pollution prevention team are provided in the following table. Title Name(s) Phone Number Certified Erosion and Sediment Control Lead Pending Project Bid (CESCL) Resident Engineer Tom Hendricks,PE 425-783-5022 Emergency Ecology Contact Northwest Region 425-649-7000 Emergency Owner Contact Tom Hendricks 425-783-5022 Non-Emergency Ecology Contact Pending Project Bid Monitoring Personnel Pending Project Bid 16 Stormwater Pollution Prevention Plan 6.0 Site Inspections and Monitoring Monitoring includes visual inspection, monitoring for water quality parameters of concern, and documentation of the inspection and monitoring findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: ■ A record of the implementation of the SWPPP and other permit requirements; ■ Site inspections; and, ■ Stormwater quality monitoring. For convenience, the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. This SWPPP may function as the site log book if desired, or the forms may be separated and included in a separate site log book. However, if separated, the site log book but must be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 6.1 Site Inspection All BMPs will be inspected, maintained, and repaired as needed to assure continued performance of their intended function. The inspector will be a Certified Erosion and Sediment Control Lead (CESCL)per BMP C160. The name and contact information for the CESCL is provided in Section 5 of this SWPPP. Site inspection will occur in all areas disturbed by construction activities and at all stormwater discharge points. Stormwater will be examined for the presence of suspended sediment, turbidity, discoloration, and oily sheen. The site inspector will evaluate and document the effectiveness of the installed BMPs and determine if it is necessary to repair or replace any of the BMPs to improve the quality of stormwater discharges. All maintenance and repairs will be documented in the site log book or forms provided in this document. All new BMPs or design changes will be documented in the SWPPP as soon as possible. 6.1.1 Site Inspection Frequency Site inspections will be conducted at least once a week and within 24 hours following any discharge from the site. For temporary stabilization inactive sites, inspection can be reduced to once per month. 6.1.2 Site Inspection Documentation The site inspector will record each site inspection using the site log inspection forms provided in Appendix E. The site inspection log forms may be separated from this SWPPP document,but will be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 17 Stormwater Pollution Prevention Plan 6.2 Stormwater Quality Monitoring 6.2.1 Turbidity Site discharge during construction could drain to the to the city catch basin at the intersection of 212th St NE and 871h Ave NE eventually discharging into Eagle Creek that discharges into the Stillaguamish River. The three sample locations will be: Sample Location A. Stormwater along the gutter of 212th St NE west of the construction site. This location will represent one potential source of upstream background turbidity. Sample Location B Stormwater in the grassy swale north of the construction site. This location will represent a second potential source of upstream background turbidity. Sample Location B. The city catch basin at the intersection of 212th St NE and 87th Ave NE labeled CB I on drawing S-4-05. This sample location represents turbidity downstream of the discharge point. Monitoring requirements for the proposed project will include either turbidity or water transparency sampling to monitor site discharges for water quality compliance with the 2016 Construction Stormwater General Permit(Appendix D). Sampling will be conducted at all discharge points at least once per calendar week. If there is no flow, the attempt to sample will be recorded in the site log book and reported to Ecology in the monthly Discharge Monitoring Report (DMR) as "No Discharge". Turbidity or transparency monitoring will follow the analytical methodologies described in Section S4 of the 2016 Construction Stormwater General Permit (Appendix D). The key benchmark values that require action are 25 NTU for turbidity(equivalent to 32 cm transparency) and 250 NTU for turbidity(equivalent to 6 cm transparency). If the 25 NTU benchmark for turbidity(equivalent to 32 cm transparency) is exceeded, the following steps will be conducted: I. Ensure all BMPs specified in this SWPPP are installed and functioning as intended. 2. Assess whether additional BMPs should be implemented, and document revisions to the SWPPP as necessary. 3. Sample discharge location daily until the analysis results are less than 25 NTU(turbidity) or greater than 32 cm(transparency). If the turbidity is greater than 25 NTU (or transparency is less than 32 cm)but less than 250 NTU(transparency greater than 6 cm) for more than 3 days, additional treatment BMPs will be implemented within 24 hours of the third consecutive sample that exceeded the benchmark value. Additional treatment BMPs to be considered will include, but are not limited to, off-site treatment, infiltration, filtration and chemical treatment. 18 Stormwater Pollution Prevention Plan If the 250 NTU benchmark for turbidity(or less than 6 cm transparency) is exceeded at any time, the following steps will be conducted: 1. Notify Ecology by phone within 24 hours of analysis (see Section 5.0 of this SWPPP for contact information). 2. Continue daily sampling until the turbidity is less than 25 NTU(or transparency is greater than 32 cm). 3. Initiate additional treatment BMPs such as off-site treatment, infiltration, filtration and chemical treatment within 24 hours of the first 250 NTU exceedance. 4. Implement additional treatment BMPs as soon as possible, but within 7 days of the first 250 NTU exceedance. 5. Describe inspection results and remedial actions taken in the site log book and in monthly discharge monitoring reports as described in Section 7.0 of this SWPPP. 6.2.2 pH Sampling 1. The project does not have "Significant concrete work" (i.e., greater than 1000 cubic yards poured concrete over the life of the project). 19 Stormwater Pollution Prevention Plan 7.0 Reporting and Recordkeeping 7.1 Recordkeeping 7.1.1 Site Log Book A site log book will be maintained for all on-site construction activities and will include: ■ A record of the implementation of the SWPPP and other permit requirements; ■ Site inspections; and, ■ Stormwater quality monitoring. For convenience, the inspection form included in this SWPPP includes the required information for the site log book. 7.1.2 Records Retention Records of all monitoring information(site log book, inspection reports/checklists, etc.), this Stormwater Pollution Prevention Plan, and any other documentation of compliance with permit requirements will be retained during the life of the construction project and for a minimum of three years following the termination of permit coverage in accordance with permit condition S5.C. 7.1.3 Access to Plans and Records The SWPPP, General Permit,Notice of Authorization letter, and Site Log Book will be retained on site or within reasonable access to the site and will be made immediately available upon request to Ecology or the local jurisdiction. A copy of this SWPPP will be provided to Ecology within 14 days of receipt of a written request for the SWPPP from Ecology. Any other information requested by Ecology will be submitted within a reasonable time. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with permit condition S5.G. 7.1.4 Updating the SWPPP In accordance with Conditions S3, S4.13, and S9.13.2 of the General Permit, this SWPPP will be modified if the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site or there has been a change in design, construction, operation, or maintenance at the site that has a significant effect on the discharge, or potential for discharge, of pollutants to the waters of the State. The SWPPP will be modified within seven days of determination based on inspection(s)that additional or modified BMPs are necessary to correct problems identified, and an updated timeline for BMP implementation will be prepared. 20 Stormwater Pollution Prevention Plan 7.2 Reporting 7.2.1 Discharge Monitoring Reports 7.2.2 Notification of Noncompliance If any of the terms and conditions of the permit are not met, and it causes a threat to human health or the environment, the following steps will be taken in accordance with permit section S5.F: l. Ecology will be immediately notified of the failure to comply. 2. Immediate action will be taken to control the noncompliance issue and to correct the problem. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days,unless requested earlier by Ecology. 7.2.3 Permit Application and Changes In accordance with permit condition S2.A, a complete application form will be submitted to Ecology and the appropriate local jurisdiction(if applicable)to be covered by the General Permit. 21 Stormwater Pollution Prevention Plan Appendix A — Site Plans Refer to Contract Drawings 22 Stormwater Pollution Prevention Plan Appendix B — Construction BMPs Preserving Natural Vegetation(BMP C 101) High Visibility Plastic or Metal Fence (BMP C 103) Stabilized Construction Entrance (BMP C 105) Construction Road/Parking Area Stabilization(BMP C107) Temporary and Permanent Seeding(BMP C 120) Plastic Covering(BMP C123) Topsoiling(BMP C125) Surface Roughening (BMP C130) Dust Control (BMP C 140) Materials on Hand (BMP C150) Concrete Handling(BMP C151) Certified Erosion and Sediment Control Lead(BMP C160) Scheduling(BMP C 162) Interceptor Swale (BMP C200) Grass-Lined Swales (BMP C201) Subsurface Drains (BMP C205) Level Spreader(BMP C206) Outlet Protection (BMP C209) Storm Drain Inlet Protection(BMP C220) Silt Fence (BMP C233) Vegetated Strip (BMP C234) Straw Wattle (BMP C235) 23 Table 4.1.1 Source Control BMPs by SWPPP Element V N U N Q U Q ate, 2yIL V) O a E' BMP or Element Name -' E r4 ° Ln i0 00 On `-' m `-' `-' 3 v u xk xz x0 xz xz xz U 0 .� a ., t u .. .. .. .. *' .. c .. .. E C i -11 C VI L C C C N N C C 'gyp C C �"� O' E r6 E �o E E Q E Oo Y E £ '�' > W v N N 0! N O Gl 'Q G1 0 01 7 Gl O T c T c Ol OL N W d � U W Lu U W Ln w Ln W U O W d W G LU G W d BMP C101:Preserving Natural ✓ Vegetation BMP C102:Buffer Zones ✓ ✓ BMP C103:High Visibility Fence ✓ ✓ BMP C105:Stabilized Construction ✓ Entrance/Exit BMP C106:Wheel Wash ✓ BMP C107:Construction Road/Parking ✓ Area Stabilization BMP C120:Temporary and Permanent ✓ ✓ Seeding BMP C121:Mulching ✓ ✓ BMP C122:Nets and Blankets ✓ ✓ ✓ BMP C123:Plastic Covering ✓ ✓ BMP C124:Sodding ✓ ✓ BMP C125:Topsoiling/Composting ✓ BMP C126:Polyacrylamide(PAM)for ✓ Soil Erosion Protection BMP C130:Surface Roughening ✓ ✓ BMP C131:Gradient Terraces ✓ ✓ BMP C140:Dust Control ✓ BMP C150:Materials on Hand ✓ ✓ BMP C151:Concrete Handling ✓ BMP C152:Sawcutting and Surfacing ✓ Pollution Prevention BMP C153:Material Delivery,Storage ✓ and Containment BMP C154:Concrete Washout Area ✓ BMP C160:Certified Erosion and ✓ ✓ Sediment Control Lead BMP C162:Scheduling ✓ Volume II— Construction Stormwater Pollution Prevention -December 2014 4-2 BMP C101: Preserving Natural Vegetation Purpose The purpose of preserving natural vegetation is to reduce erosion wherever practicable. Limiting site disturbance is the single most effective method for reducing erosion. For example, conifers can hold up to about 50 percent of all rain that falls during a storm. Up to 20-30 percent of this rain may never reach the ground but is taken up by the tree or evaporates. Another benefit is that the rain held in the tree can be released slowly to the ground after the storm. Conditions of Use Natural vegetation should be preserved on steep slopes, near perennial and intermittent watercourses or swales, and on building sites in wooded areas. • As required by local governments. • Phase construction to preserve natural vegetation on the project site for as long as possible during the construction period. Design and Natural vegetation can be preserved in natural clumps or as individual Installation trees, shrubs and vines. Specifications The preservation of individual plants is more difficult because heavy equipment is generally used to remove unwanted vegetation. The points to remember when attempting to save individual plants are: • Is the plant worth saving? Consider the location, species, size, age,vigor, and the work involved. Local governments may also have ordinances to save natural vegetation and trees. • Fence or clearly mark areas around trees that are to be saved. It is preferable to keep ground disturbance away from the trees at least as far out as the dripline. Plants need protection from three kinds of injuries: • Construction Equipment- This injury can be above or below the ground level. Damage results from scarring, cutting of roots, and compaction of the soil. Placing a fenced buffer zone around plants to be saved prior to construction can prevent construction equipment injuries. • Grade Changes - Changing the natural ground level will alter grades, which affects the plant's ability to obtain the necessary air, water, and minerals. Minor fills usually do not cause problems although sensitivity between species does vary and should be checked. Trees can typically tolerate fill of 6 inches or less. For shrubs and other plants, the fill should be less. When there are major changes in grade, it may become necessary to supply air to the roots of plants. This can be done by placing a layer of gravel and a tile system over the roots before the fill is made. A tile Volume II—Construction Stormwater Pollution Prevention-December 2014 4-3 system protects a tree from a raised grade. The tile system should be laid out on the original grade leading from a dry well around the tree trunk. The system should then be covered with small stones to allow air to circulate over the root area. Lowering the natural ground level can seriously damage trees and shrubs. The highest percentage of the plant roots are in the upper 12 inches of the soil and cuts of only 2-3 inches can cause serious injury. To protect the roots it may be necessary to terrace the immediate area around the plants to be saved. If roots are exposed, construction of retaining walls may be needed to keep the soil in place. Plants can also be preserved by leaving them on an undisturbed, gently sloping mound. To increase the chances for survival, it is best to limit grade changes and other soil disturbances to areas outside the dripline of the plant. • Excavations -Protect trees and other plants when excavating for drainfields, power, water, and sewer lines. Where possible, the trenches should be routed around trees and large shrubs. When this is not possible, it is best to tunnel under them. This can be done with hand tools or with power augers. If it is not possible to route the trench around plants to be saved, then the following should be observed: Cut as few roots as possible. When you have to cut, cut clean. Paint cut root ends with a wood dressing like asphalt base paint if roots will be exposed for more than 24-hours. Backfill the trench as soon as possible. Tunnel beneath root systems as close to the center of the main trunk to preserve most of the important feeder roots. Some problems that can be encountered with a few specific trees are: • Maple, Dogwood, Red alder, Western hemlock, Western red cedar, and Douglas fir do not readily adjust to changes in environment and special care should be taken to protect these trees. • The windthrow hazard of Pacific silver fir and madrona is high, while that of Western hemlock is moderate. The danger of windthrow increases where dense stands have been thinned. Other species (unless they are on shallow, wet soils less than 20 inches deep) have a low windthrow hazard. • Cottonwoods, maples, and willows have water-seeking roots. These can cause trouble in sewer lines and infiltration fields. On the other hand, they thrive in high moisture conditions that other trees would not. • Thinning operations in pure or mixed stands of Grand fir, Pacific silver fir,Noble fir, Sitka spruce, Western red cedar, Western hemlock, Pacific dogwood, and Red alder can cause serious disease problems. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-4 Disease can become established through damaged limbs, trunks, roots, and freshly cut stumps. Diseased and weakened trees are also susceptible to insect attack. Maintenance Inspect flagged and/or fenced areas regularly to make sure flagging or Standards fencing has not been removed or damaged. If the flagging or fencing has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. • If tree roots have been exposed or injured, "prune" cleanly with an appropriate pruning saw or loppers directly above the damaged roots and recover with native soils. Treatment of sap flowing trees (fir, hemlock,pine, soft maples) is not advised as sap forms a natural healing barrier. BMP C102: Buffer Zones Purpose Creation of an undisturbed area or strip of natural vegetation or an established suitable planting that will provide a living filter to reduce soil erosion and runoff velocities. Conditions of Use Natural buffer zones are used along streams, wetlands and other bodies of water that need protection from erosion and sedimentation. Vegetative buffer zones can be used to protect natural swales and can be incorporated into the natural landscaping of an area. Critical-areas buffer zones should not be used as sediment treatment areas. These areas shall remain completely undisturbed. The local permitting authority may expand the buffer widths temporarily to allow the use of the expanded area for removal of sediment. Design and • Preserving natural vegetation or plantings in clumps,blocks, or strips Installation is generally the easiest and most successful method. Specifications Leave all unstable steep slopes in natural vegetation. • Mark clearing limits and keep all equipment and construction debris out of the natural areas and buffer zones. Steel construction fencing is the most effective method in protecting sensitive areas and buffers. Alternatively, wire-backed silt fence on steel posts is marginally effective. Flagging alone is typically not effective. • Keep all excavations outside the dripline of trees and shrubs. • Do not push debris or extra soil into the buffer zone area because it will cause damage from burying and smothering. • Vegetative buffer zones for streams, lakes or other waterways shall be established by the local permitting authority or other state or federal permits or approvals. Maintenance Inspect the area frequently to make sure flagging remains in place and the Standards area remains undisturbed. Replace all damaged flagging immediately. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-5 BMP C103: High Visibility Fence Purpose Fencing is intended to: l. Restrict clearing to approved limits. 2. Prevent disturbance of sensitive areas, their buffers, and other areas required to be left undisturbed. 3. Limit construction traffic to designated construction entrances, exits, or internal roads. 4. Protect areas where marking with survey tape may not provide adequate protection. Conditions of Use To establish clearing limits plastic, fabric, or metal fence may be used: • At the boundary of sensitive areas, their buffers, and other areas required to be left uncleared. • As necessary to control vehicle access to and on the site. Design and High visibility plastic fence shall be composed of a high-density Installation polyethylene material and shall be at least four feet in height. Posts for Specifications the fencing shall be steel or wood and placed every 6 feet on center (maximum) or as needed to ensure rigidity. The fencing shall be fastened to the post every six inches with a polyethylene tie. On long continuous lengths of fencing, a tension wire or rope shall be used as a top stringer to prevent sagging between posts. The fence color shall be high visibility orange. The fence tensile strength shall be 360 lbs./ft. using the ASTM D4595 testing method. If appropriate install fabric silt fence in accordance with BMP C233 to act as high visibility fence. Silt fence shall be at least 3 feet high and must be highly visible to meet the requirements of this BMP. Metal fences shall be designed and installed according to the manufacturer's specifications. Metal fences shall be at least 3 feet high and must be highly visible. Fences shall not be wired or stapled to trees. Maintenance If the fence has been damaged or visibility reduced, it shall be repaired or Standards replaced immediately and visibility restored. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-6 BMP C105: Stabilized Construction Entrance / Exit Purpose Stabilized Construction entrances are established to reduce the amount of sediment transported onto paved roads by vehicles or equipment. This is done by constructing a stabilized pad of quarry spalls at entrances and exits for construction sites. Conditions of Use Construction entrances shall be stabilized wherever traffic will be entering or leaving a construction site if paved roads or other paved areas are within 1,000 feet of the site. For residential construction provide stabilized construction entrances for each residence, rather than only at the main subdivision entrance. Stabilized surfaces shall be of sufficient length/width to provide vehicle access/parking,based on lot size/configuration. On large commercial, highway, and road projects, the designer should include enough extra materials in the contract to allow for additional stabilized entrances not shown in the initial Construction SWPPP. It is difficult to determine exactly where access to these projects will take place; additional materials will enable the contractor to install them where needed. Design and See Figure 4.1.1 for details. Note: the 100' minimum length of the Installation entrance shall be reduced to the maximum practicable size when the size Specifications or configuration of the site does not allow the full length(100'). Construct stabilized construction entrances with a 12-inch thick pad of 4- inch to 8-inch quarry spalls, a 4-inch course of asphalt treated base (ATB), or use existing pavement. Do not use crushed concrete, cement, or calcium chloride for construction entrance stabilization because these products raise pH levels in stormwater and concrete discharge to surface waters of the State is prohibited. A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into the rock pad. The geotextile shall meet the following standards: Grab Tensile Strength(ASTM D4751) 200 psi min. Grab Tensile Elongation(ASTM 30%max. D4632) Mullen Burst Strength (ASTM 400 psi min. D3786-80a) AOS (ASTM D4751) 20-45 (U.S. standard sieve size) • Consider early installation of the first lift of asphalt in areas that will paved; this can be used as a stabilized entrance. Also consider the installation of excess concrete as a stabilized entrance. During large concrete pours, excess concrete is often available for this purpose. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-7 • Fencing(see BMP C 103) shall be installed as necessary to restrict traffic to the construction entrance. • Whenever possible, the entrance shall be constructed on a firm, compacted subgrade. This can substantially increase the effectiveness of the pad and reduce the need for maintenance. • Construction entrances should avoid crossing existing sidewalks and back of walk drains if at all possible. If a construction entrance must cross a sidewalk or back of walk drain, the full length of the sidewalk and back of walk drain must be covered and protected from sediment leaving the site. Maintenance Quarry spalls shall be added if the pad is no longer in accordance with Standards the specifications. • If the entrance is not preventing sediment from being tracked onto pavement, then alternative measures to keep the streets free of sediment shall be used. This may include replacement/cleaning of the existing quarry spalls, street sweeping, an increase in the dimensions of the entrance, or the installation of a wheel wash. • Any sediment that is tracked onto pavement shall be removed by shoveling or street sweeping. The sediment collected by sweeping shall be removed or stabilized on site. The pavement shall not be cleaned by washing down the street, except when high efficiency sweeping is ineffective and there is a threat to public safety. If it is necessary to wash the streets, the construction of a small sump to contain the wash water shall be considered. The sediment would then be washed into the sump where it can be controlled. • Perform street sweeping by hand or with a high efficiency sweeper. Do not use a non-high efficiency mechanical sweeper because this creates dust and throws soils into storm systems or conveyance ditches. • Any quarry spalls that are loosened from the pad, which end up on the roadway shall be removed immediately. • If vehicles are entering or exiting the site at points other than the construction entrance(s), fencing(see BMP C 103) shall be installed to control traffic. • Upon project completion and site stabilization, all construction accesses intended as permanent access for maintenance shall be permanently stabilized. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-8 Driveway shall meet the requnEments ofthe perniorng agency It is recommended that the entrance be crowned so that mnoffdrams offthe pad A" A'� ]ustall driveway culvert&there is a roadside ditch present 4'—8"auanv malls Geotextae 12"min.thickness f '1 Provide 0 NNidth of in=ss/e=ss area Figure 4.1.1 —Stabilized Construction Entrance Approved as Ecology has approved products as able to meet the requirements of BMP Equivalent C 105. The products did not pass through the Technology Assessment Protocol—Ecology(TAPE)process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at http://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html BMP C106: Wheel Wash Purpose Wheel washes reduce the amount of sediment transported onto paved roads by motor vehicles. Conditions of Use When a stabilized construction entrance (see BMP C 105) is not preventing sediment from being tracked onto pavement. • Wheel washing is generally an effective BMP when installed with careful attention to topography. For example, a wheel wash can be detrimental if installed at the top of a slope abutting a right-of-way where the water from the dripping truck can run unimpeded into the street. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-9 • Pressure washing combined with an adequately sized and surfaced pad with direct drainage to a large 10-foot x I0-foot sump can be very effective. • Discharge wheel wash or tire bath wastewater to a separate on-site treatment system that prevents discharge to surface water, such as closed-loop recirculation or upland land application, or to the sanitary sewer with local sewer district approval. • Wheel wash or tire bath wastewater should not include wastewater from concrete washout areas. Design and Suggested details are shown in Figure 4.1.2. The Local Permitting Installation Authority may allow other designs. A minimum of 6 inches of asphalt Specifications treated base (ATB) over crushed base material or 8 inches over a good subgrade is recommended to pave the wheel wash. Use a low clearance truck to test the wheel wash before paving. Either a belly dump or lowboy will work well to test clearance. Keep the water level from 12 to 14 inches deep to avoid damage to truck hubs and filling the truck tongues with water. Midpoint spray nozzles are only needed in extremely muddy conditions. Wheel wash systems should be designed with a small grade change, 6-to 12-inches for a 10-foot-wide pond, to allow sediment to flow to the low side of pond to help prevent re-suspension of sediment. A drainpipe with a 2-to 3-foot riser should be installed on the low side of the pond to allow for easy cleaning and refilling. Polymers may be used to promote coagulation and flocculation in a closed-loop system. Polyacrylamide (PAM) added to the wheel wash water at a rate of 0.25 - 0.5 pounds per 1,000 gallons of water increases effectiveness and reduces cleanup time. If PAM is already being used for dust or erosion control and is being applied by a water truck, the same truck can be used to change the wash water. Maintenance The wheel wash should start out the day with fresh water. Standards The wash water should be changed a minimum of once per day. On large earthwork jobs where more than 10-20 trucks per hour are expected, the wash water will need to be changed more often. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-10 6" SEWER PIPE WITH 3" TRASH PUMP WITH FLOATS BUTTERFLY VALVES A ON SUCTION HOSE 2" SCHEDULE 40 8'x8' SUMP WITH 5' 1-1/2" SCHEDULE 40 OF CATCH FOR SPRAYERS 2X MIDPOINT SPRAY NOZZLES SLOPE 5:1 f'�?'1 'It I IF NEEDED � SLOPE SLOPE i 2X SLOPE 1.1 6" ATB CONSTRUCTION SLOPE ENTRANCE 15' ATB APRON TO PROTECT A BALL VALVES \ \� GROUND FROM SPLASHING WATER ASPHALT CURB ON THE 6" SLEEVE UNDER ROAD LOW ROAD SIDE TO DIRECT WATER BACK TO POND PLAN VIEW 15' 15' 20' 1 15' 1 50' CURB 6" SLEEVE ELEVATION VIEW LOCATE INVERT OF TOP PIPE 1' ABOVE BOTTOM OF WHEEL WASH 18' 8'x8' SUMP WATER LEVEL -\-,I IR111 3' 5' 12' DRAIN PIPE V1:1 SLOPE SECTION A-A NOTES: 1. BUILD 8'x8' SUMP TO ACCOMODATE CLEANING BY TRACKHOE. Figure 4.1.2 —Wheel Wash Notes: 1. Asphalt construction entrance 6 in. asphalt treated base (ATB). 2. 3-inch trash pump with floats on the suction hose. 3. Midpoint spray nozzles, if needed. 4. 6-inch sewer pipe with butterfly valves. Bottom one is a drain. Locate top pipe's invert 1 foot above bottom of wheel wash. 5. 8 foot x 8 foot sump with 5 feet of catch. Build so the sump can be cleaned with a trackhoe. 6. Asphalt curb on the low road side to direct water back to pond. 7. 6-inch sleeve under road. 8. Ball valves. 9. 15 foot. ATB apron to protect ground from splashing water. Volume II— Construction Stormwater Pollution Prevention -December 2014 4-11 BMP C107: Construction Road/Parking Area Stabilization Purpose Stabilizing subdivision roads, parking areas, and other on-site vehicle transportation routes immediately after grading reduces erosion caused by construction traffic or runoff. Conditions of Use Roads or parking areas shall be stabilized wherever they are constructed, whether permanent or temporary, for use by construction traffic. High Visibility Fencing(see BMP C103) shall be installed, if necessary, to limit the access of vehicles to only those roads and parking areas that are stabilized. Design and • On areas that will receive asphalt as part of the project, install the first Installation lift as soon as possible. Specifications • A 6-inch depth of 2-to 4-inch crushed rock, gravel base, or crushed surfacing base course shall be applied immediately after grading or utility installation. A 4-inch course of asphalt treated base (ATB) may also be used, or the road/parking area may be paved. It may also be possible to use cement or calcium chloride for soil stabilization. If cement or cement kiln dust is used for roadbase stabilization, pH monitoring and BMPs (BMPs C252 and C253) are necessary to evaluate and minimize the effects on stormwater. If the area will not be used for permanent roads,parking areas, or structures, a 6-inch depth of hog fuel may also be used, but this is likely to require more maintenance. Whenever possible, construction roads and parking areas shall be placed on a firm, compacted subgrade. • Temporary road gradients shall not exceed 15 percent. Roadways shall be carefully graded to drain. Drainage ditches shall be provided on each side of the roadway in the case of a crowned section, or on one side in the case of a super-elevated section. Drainage ditches shall be directed to a sediment control BMP. Rather than relying on ditches, it may also be possible to grade the road so that runoff sheet-flows into a heavily vegetated area with a well-developed topsoil. Landscaped areas are not adequate. If this area has at least 50 feet of vegetation that water can flow through, then it is generally preferable to use the vegetation to treat runoff, rather than a sediment pond or trap. The 50 feet shall not include wetlands or their buffers. If runoff is allowed to sheetflow through adjacent vegetated areas, it is vital to design the roadways and parking areas so that no concentrated runoff is created. • Storm drain inlets shall be protected to prevent sediment-laden water entering the storm drain system (see BMP C220). Maintenance Inspect stabilized areas regularly, especially after large storm events. Standards Crushed rock, gravel base, etc., shall be added as required to maintain a Volume II—Construction Stormwater Pollution Prevention-December 2014 4-12 stable driving surface and to stabilize any areas that have eroded. Following construction, these areas shall be restored to pre-construction condition or better to prevent future erosion. Perform street cleaning at the end of each day or more often if necessary. BMP C120: Temporary and Permanent Seeding Purpose Seeding reduces erosion by stabilizing exposed soils. A well-established vegetative cover is one of the most effective methods of reducing erosion. Conditions of Use Use seeding throughout the project on disturbed areas that have reached final grade or that will remain unworked for more than 30 days. The optimum seeding windows for western Washington are April 1 through June 30 and September 1 through October 1. Between July 1 and August 30 seeding requires irrigation until 75 percent grass cover is established. Between October 1 and March 30 seeding requires a cover of mulch with straw or an erosion control blanket until 75 percent grass cover is established. Review all disturbed areas in late August to early September and complete all seeding by the end of September. Otherwise, vegetation will not establish itself enough to provide more than average protection. • Mulch is required at all times for seeding because it protects seeds from heat, moisture loss, and transport due to runoff. Mulch can be applied on top of the seed or simultaneously by hydroseeding. See BMP C 121: Mulching for specifications. • Seed and mulch, all disturbed areas not otherwise vegetated at final site stabilization. Final stabilization means the completion of all soil disturbing activities at the site and the establishment of a permanent vegetative cover, or equivalent permanent stabilization measures (such as pavement, riprap, gabions, or geotextiles)which will prevent erosion. Design and Seed retention/detention ponds as required. Installation Install channels intended for vegetation before starting major Specifications earthwork and hydroseed with a Bonded Fiber Matrix. For vegetated channels that will have high flows, install erosion control blankets over hydroseed. Before allowing water to flow in vegetated channels, establish 75 percent vegetation cover. If vegetated channels cannot be established by seed before water flow; install sod in the channel bottom—over hydromulch and erosion control blankets. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-13 • Confirm the installation of all required surface water control measures to prevent seed from washing away. • Hydroseed applications shall include a minimum of 1,500 pounds per acre of mulch with 3 percent tackifier. See BMP C 121: Mulching for specifications. • Areas that will have seeding only and not landscaping may need compost or meal-based mulch included in the hydroseed in order to establish vegetation. Re-install native topsoil on the disturbed soil surface before application. • When installing seed via hydroseeding operations, only about 1/3 of the seed actually ends up in contact with the soil surface. This reduces the ability to establish a good stand of grass quickly. To overcome this, consider increasing seed quantities by up to 50 percent. • Enhance vegetation establishment by dividing the hydromulch operation into two phases: 1. Phase 1- Install all seed and fertilizer with 25-30 percent mulch and tackifier onto soil in the first lift. 2. Phase 2- Install the rest of the mulch and tackifier over the first lift. Or, enhance vegetation by: 1. Installing the mulch, seed, fertilizer, and tackifier in one lift. 2. Spread or blow straw over the top of the hydromulch at a rate of 800-1000 pounds per acre. 3. Hold straw in place with a standard tackifier. Both of these approaches will increase cost moderately but will greatly improve and enhance vegetative establishment. The increased cost may be offset by the reduced need for: • Irrigation. • Reapplication of mulch. • Repair of failed slope surfaces. This technique works with standard hydromulch(1,500 pounds per acre minimum) and BFM/MBFMs (3,000 pounds per acre minimum). • Seed may be installed by hand if: • Temporary and covered by straw, mulch, or topsoil. • Permanent in small areas (usually less than 1 acre) and covered with mulch, topsoil, or erosion blankets. • The seed mixes listed in the tables below include recommended mixes for both temporary and permanent seeding. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-14 • Apply these mixes, with the exception of the wetland mix, at a rate of 120 pounds per acre. This rate can be reduced if soil amendments or slow-release fertilizers are used. • Consult the local suppliers or the local conservation district for their recommendations because the appropriate mix depends on a variety of factors, including location, exposure, soil type, slope, and expected foot traffic. Alternative seed mixes approved by the local authority may be used. • Other mixes may be appropriate, depending on the soil type and hydrology of the area. • Table 4.1.2 lists the standard mix for areas requiring a temporary vegetative cover. Table 4.1.2 Temporary Erosion Control Seed Mix %Weight %Puri %Germination Chewings or annual blue grass 40 98 90 Festuca rubra var. commutata or Poa anna Perennial rye - 50 98 90 Lolium perenne Redtop or colonial bentgrass 5 92 85 Agrostis alba or Agrostis tenuis White dutch clover 5 98 90 Trifolium repens • Table 4.1.3 lists a recommended mix for landscaping seed. Table 4.1.3 Landscaping Seed Mix %Weight %Puri %Germination Perennial rye blend 70 98 90 Lolium perenne Chewings and red fescue blend 30 98 90 Festuca rubra var. commutata or Festuca rubra Volume II—Construction Stormwater Pollution Prevention -December 2014 4-15 • Table 4.1.4 lists a turf seed mix for dry situations where there is no need for watering. This mix requires very little maintenance. Table 4.1.4 Low-Growing Turf Seed Mix %Wei ht %Puri %Germination Dwarf tall fescue (several varieties) 45 98 90 Festuca arundinacea var. Dwarf perennial rye (Barclay) 30 98 90 Lolium perenne var. Barclay Red fescue 20 98 90 Festuca rubra Colonial bentgrass 5 98 90 Agrostis tenuis • Table 4.1.5 lists a mix for bioswales and other intermittently wet areas. Table 4.1.5 Bioswale Seed Mix* %Wei ht %Puri %Germination Tall or meadow fescue 75-80 98 90 Festuca arundinacea or Festuca elation Seaside/Creeping bentgrass 10-15 92 85 Agrostis palustris Redtop bentgrass 5-10 90 80 Agrostis alba or Agrostis gigantea *Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix Volume II—Construction Stormwater Pollution Prevention -December 2014 4-16 • Table 4.1.6 lists a low-growing, relatively non-invasive seed mix appropriate for very wet areas that are not regulated wetlands. Apply this mixture at a rate of 60 pounds per acre. Consult Hydraulic Permit Authority(HPA) for seed mixes if applicable. Table 4.1.6 Wet Area Seed Mix* %Wei ht %Puri %Germination Tall or meadow fescue 60-70 98 90 Festuca arundinacea or Festuca elation Seaside/Creeping bentgrass 10-15 98 85 Agrostis palustris Meadow foxtail 10-15 90 80 Alepocurus pratensis Alsike clover 1-6 98 90 Trifolium hybridum Redtop bentgrass 1-6 92 85 Agrostis alba *Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix • Table 4.1.7 lists a recommended meadow seed mix for infrequently maintained areas or non-maintained areas where colonization by native plants is desirable. Likely applications include rural road and utility right-of-way. Seeding should take place in September or very early October in order to obtain adequate establishment prior to the winter months. Consider the appropriateness of clover, a fairly invasive species, in the mix. Amending the soil can reduce the need for clover. Table 4.1.7 Meadow Seed Mix %Wei ht %Puri %Germination Redtop or Oregon bentgrass 20 92 85 Agrostis alba or Agrostis oregonensis Red fescue 70 98 90 Festuca rubra White dutch clover 10 98 90 Trifolium repens Volume II—Construction Stormwater Pollution Prevention -December 2014 4-17 • Roughening and Rototilling: • The seedbed should be firm and rough. Roughen all soil no matter what the slope. Track walk slopes before seeding if engineering purposes require compaction. Backblading or smoothing of slopes greater than 4H:1 V is not allowed if they are to be seeded. • Restoration-based landscape practices require deeper incorporation than that provided by a simple single-pass rototilling treatment. Wherever practical, initially rip the subgrade to improve long-term permeability, infiltration, and water inflow qualities. At a minimum,permanent areas shall use soil amendments to achieve organic matter and permeability performance defined in engineered soil/landscape systems. For systems that are deeper than 8 inches complete the rototilling process in multiple lifts, or prepare the engineered soil system per specifications and place to achieve the specified depth. • Fertilizers: • Conducting soil tests to determine the exact type and quantity of fertilizer is recommended. This will prevent the over-application of fertilizer. • Organic matter is the most appropriate form of fertilizer because it provides nutrients (including nitrogen, phosphorus, and potassium) in the least water-soluble form. • In general,use 10-4-6 N-P-K(nitrogen-phosphorus-potassium) fertilizer at a rate of 90 pounds per acre. Always use slow-release fertilizers because they are more efficient and have fewer environmental impacts. Do not add fertilizer to the hydromulch machine, or agitate, more than 20 minutes before use. Too much agitation destroys the slow-release coating. • There are numerous products available that take the place of chemical fertilizers. These include several with seaweed extracts that are beneficial to soil microbes and organisms. If 100 percent cottonseed meal is used as the mulch in hydroseed, chemical fertilizer may not be necessary. Cottonseed meal provides a good source of long-term, slow-release, available nitrogen. • Bonded Fiber Matrix and Mechanically Bonded Fiber Matrix: • On steep slopes use Bonded Fiber Matrix (BFM) or Mechanically Bonded Fiber Matrix (MBFM)products. Apply BFM/MBFM products at a minimum rate of 3,000 pounds per acre of mulch with approximately 10 percent tackifier. Achieve a minimum of 95 percent soil coverage during application. Numerous products are available commercially. Installed products per manufacturer's instructions. Most products require 24-36 hours to cure before rainfall and cannot be installed on wet or saturated soils. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-18 Generally, products come in 40-50 pound bags and include all necessary ingredients except for seed and fertilizer. • BFMs and MBFMs provide good alternatives to blankets in most areas requiring vegetation establishment. Advantages over blankets include: • BFM and MBFMs do not require surface preparation. • Helicopters can assist in installing BFM and MBFMs in remote areas. • On slopes steeper than 2.5H:IV, blanket installers may require ropes and harnesses for safety. • Installing BFM and MBFMs can save at least 51,000 per acre compared to blankets. Maintenance Reseed any seeded areas that fail to establish at least 80 percent cover Standards (100 percent cover for areas that receive sheet or concentrated flows). If reseeding is ineffective, use an alternate method such as sodding, mulching, or nets/blankets. If winter weather prevents adequate grass growth, this time limit may be relaxed at the discretion of the local authority when sensitive areas would otherwise be protected. • Reseed and protect by mulch any areas that experience erosion after achieving adequate cover. Reseed and protect by mulch any eroded area. • Supply seeded areas with adequate moisture, but do not water to the extent that it causes runoff. Approved as Ecology has approved products as able to meet the requirements of BMP Equivalent C120. The products did not pass through the Technology Assessment Protocol—Ecology(TAPE)process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at hM2://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html. BMP C121: Mulching Purpose Mulching soils provides immediate temporary protection from erosion. Mulch also enhances plant establishment by conserving moisture, holding fertilizer, seed, and topsoil in place, and moderating soil temperatures. There is an enormous variety of mulches that can be used. This section discusses only the most common types of mulch. Conditions of Use As a temporary cover measure, mulch should be used: • For less than 30 days on disturbed areas that require cover. • At all times for seeded areas, especially during the wet season and during the hot summer months. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-19 • During the wet season on slopes steeper than 3H:1V with more than 10 feet of vertical relief. Mulch may be applied at any time of the year and must be refreshed periodically. • For seeded areas mulch may be made up of 100 percent: cottonseed meal; fibers made of wood, recycled cellulose, hemp, kenaf; compost; or blends of these. Tackifier shall be plant-based, such as guar or alpha plantago, or chemical-based such as polyacrylamide or polymers. Any mulch or tackifier product used shall be installed per manufacturer's instructions. Generally, mulches come in 40-50 pound bags. Seed and fertilizer are added at time of application. Design and For mulch materials, application rates, and specifications, see Table 4.1.8. Installation Always use a 2-inch minimum mulch thickness; increase the thickness Specifications until the ground is 95% covered(i.e. not visible under the mulch layer). Note: Thickness may be increased for disturbed areas in or near sensitive areas or other areas highly susceptible to erosion. Where the option of"Compost" is selected, it should be a coarse compost that meets the following size gradations when tested in accordance with the U.S. Composting Council "Test Methods for the Examination of Compost and Composting" (TMECC) Test Method 02.02-B. Coarse Compost Minimum Percent passing 3" sieve openings 100% Minimum Percent passing 1" sieve openings 90% Minimum Percent passing 3/4" sieve openings 70% Minimum Percent passing '/4" sieve openings 40% Mulch used within the ordinary high-water mark of surface waters should be selected to minimize potential flotation of organic matter. Composted organic materials have higher specific gravities (densities) than straw, wood, or chipped material. Consult Hydraulic Permit Authority(HPA) for mulch mixes if applicable. Maintenance • The thickness of the cover must be maintained. Standards • Any areas that experience erosion shall be remulched and/or protected with a net or blanket. If the erosion problem is drainage related, then the problem shall be fixed and the eroded area remulched. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-20 Table 4.1.8 Mulch Standards and Guidelines Application Mulch Material Quality Standards Rates Remarks Straw Air-dried;free from 2"-3"thick;5 Cost-effective protection when applied with adequate thickness. undesirable seed and bales per 1,000 Hand-application generally requires greater thickness than coarse material. sf or 2-3 tons per blown straw.The thickness of straw may be reduced by half acre when used in conjunction with seeding.In windy areas straw must be held in place by crimping,using a tackifier,or covering with netting.Blown straw always has to be held in place with a tackifier as even light winds will blow it away. Straw,however, has several deficiencies that should be considered when selecting mulch materials.It often introduces and/or encourages the propagation of weed species and it has no significant long- term benefits.It should also not be used within the ordinary high-water elevation of surface waters(due to flotation). Hydromulch No growth Approx.25-30 Shall be applied with hydromulcher. Shall not be used without inhibiting factors. lbs per 1,000 sf seed and tackifier unless the application rate is at least doubled. or 1,500-2,000 Fibers longer than about 3/4-1 inch clog hydromulch equipment. lbs per acre Fibers should be kept to less than 3/4 inch. Compost No visible water or 2"thick min.; More effective control can be obtained by increasing thickness dust during approx. 100 tons to 3".Excellent mulch for protecting final grades until handling.Must be per acre(approx. landscaping because it can be directly seeded or tilled into soil produced per WAC 800 lbs per yard) as an amendment.Compost used for mulch has a coarser size 173-350,Solid gradation than compost used for BMP C125 or BMP T5.13(see Waste Handling Chapter 5 of Volume V of this manual)It is more stable and Standards,but may practical to use in wet areas and during rainy weather have up to 35% conditions.Do not use near wetlands or near phosphorous biosolids. impaired water bodies. Chipped Site Average size shall 2"thick min.; This is a cost-effective way to dispose of debris from clearing Vegetation be several inches. and grubbing,and it eliminates the problems associated with Gradations from burning.Generally,it should not be used on slopes above fines to 6 inches in approx. 10%because of its tendency to be transported by length for texture, runoff.It is not recommended within 200 feet of surface waters. variation,and If seeding is expected shortly after mulch,the decomposition of interlocking the chipped vegetation may tie up nutrients important to grass properties. establishment. Wood-based No visible water or 2"thick min.; This material is often called"hog or hogged fuel."The use of Mulch or Wood dust during approx. 100 tons mulch ultimately improves the organic matter in the soil. Straw handling.Must be per acre(approx. Special caution is advised regarding the source and composition purchased from a 800 lbs.per of wood-based mulches.Its preparation typically does not supplier with a Solid cubic yard) provide any weed seed control,so evidence of residual Waste Handling vegetation in its composition or known inclusion of weed plants Permit or one or seeds should be monitored and prevented(or minimized). exempt from solid waste regulations. Wood Strand A blend of loose, 2"thick min. Cost-effective protection when applied with adequate thickness. Mulch long,thin wood A minimum of 95-percent of the wood strand shall have lengths pieces derived from between 2 and 10-inches,with a width and thickness between native conifer or 1/16 and%-inches.The mulch shall not contain resin,tannin,or deciduous trees with other compounds in quantities that would be detrimental to plant high length-to-width life. Sawdust or wood shavings shall not be used as mulch. ratio. (WSDOT specification(9-14.4(4)) Volume II—Construction Stormwater Pollution Prevention -December 2014 4-21 BMP C122: Nets and Blankets Purpose Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so that vegetation can become well established. In addition, some nets and blankets can be used to permanently reinforce turf to protect drainage ways during high flows. Nets (commonly called matting) are strands of material woven into an open, but high-tensile strength net(for example, coconut fiber matting). Blankets are strands of material that are not tightly woven,but instead form a layer of interlocking fibers, typically held together by a biodegradable or photodegradable netting (for example, excelsior or straw blankets). They generally have lower tensile strength than nets,but cover the ground more completely. Coir(coconut fiber) fabric comes as both nets and blankets. Conditions of Use Erosion control nets and blankets should be used: • To aid permanent vegetated stabilization of slopes 2H:I V or greater and with more than 10 feet of vertical relief. • For drainage ditches and swales (highly recommended). The application of appropriate netting or blanket to drainage ditches and swales can protect bare soil from channelized runoff while vegetation is established. Nets and blankets also can capture a great deal of sediment due to their open, porous structure. Nets and blankets can be used to permanently stabilize channels and may provide a cost- effective, environmentally preferable alternative to riprap. 100 percent synthetic blankets manufactured for use in ditches may be easily reused as temporary ditch liners. Disadvantages of blankets include: • Surface preparation required. • On slopes steeper than 2.5H:1 V, blanket installers may need to be roped and harnessed for safety. • They cost at least$4,000-6,000 per acre installed. Advantages of blankets include: • Installation without mobilizing special equipment. • Installation by anyone with minimal training • Installation in stages or phases as the project progresses. • Installers can hand place seed and fertilizer as they progress down the slope. • Installation in any weather. • There are numerous types of blankets that can be designed with various parameters in mind. Those parameters include: fiber blend, mesh strength, longevity, biodegradability, cost, and availability. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-22 Design and See Figure 4.1.3 and Figure 4.1.4 for typical orientation and Installation installation of blankets used in channels and as slope protection. Note: Specifications these are typical only; all blankets must be installed per manufacturer's installation instructions. • Installation is critical to the effectiveness of these products. If good ground contact is not achieved, runoff can concentrate under the product, resulting in significant erosion. • Installation of Blankets on Slopes: 1. Complete final grade and track walk up and down the slope. 2. Install hydromulch with seed and fertilizer. 3. Dig a small trench, approximately 12 inches wide by 6 inches deep along the top of the slope. 4. Install the leading edge of the blanket into the small trench and staple approximately every 18 inches. NOTE: Staples are metal, "U"-shaped, and a minimum of 6 inches long. Longer staples are used in sandy soils. Biodegradable stakes are also available. 5. Roll the blanket slowly down the slope as installer walks backwards. NOTE: The blanket rests against the installer's legs. Staples are installed as the blanket is unrolled. It is critical that the proper staple pattern is used for the blanket being installed. The blanket is not to be allowed to roll down the slope on its own as this stretches the blanket making it impossible to maintain soil contact. In addition, no one is allowed to walk on the blanket after it is in place. 6. If the blanket is not long enough to cover the entire slope length, the trailing edge of the upper blanket should overlap the leading edge of the lower blanket and be stapled. On steeper slopes, this overlap should be installed in a small trench, stapled, and covered with soil. • With the variety of products available, it is impossible to cover all the details of appropriate use and installation. Therefore, it is critical that the design engineer consult the manufacturer's information and that a site visit takes place in order to ensure that the product specified is appropriate. Information is also available at the following web sites: 1. WSDOT (Section 3.2.4): http://www.wsdot.wa.gov/NR/rdonl3 res/3B41E087-FA86-4717- 932D-D7A8556CCD57/0/ErosionTraininrManual.pdf 2. Texas Transportation Institute: hqp://www.txdot.gov/business/doing business/product_evaluation/ erosion control.htm Volume II—Construction Stormwater Pollution Prevention -December 2014 4-23 • Use jute matting in conjunction with mulch(BMP C121). Excelsior, woven straw blankets and coir(coconut fiber)blankets may be installed without mulch. There are many other types of erosion control nets and blankets on the market that may be appropriate in certain circumstances. • In general, most nets (e.g.,jute matting) require mulch in order to prevent erosion because they have a fairly open structure. Blankets typically do not require mulch because they usually provide complete protection of the surface. • Extremely steep,unstable, wet, or rocky slopes are often appropriate candidates for use of synthetic blankets, as are riverbanks,beaches and other high-energy environments. If synthetic blankets are used, the soil should be hydromulched first. • 100-percent biodegradable blankets are available for use in sensitive areas. These organic blankets are usually held together with a paper or fiber mesh and stitching which may last up to a year. • Most netting used with blankets is photodegradable, meaning they break down under sunlight(not UV stabilized). However, this process can take months or years even under bright sun. Once vegetation is established, sunlight does not reach the mesh. It is not uncommon to find non-degraded netting still in place several years after installation. This can be a problem if maintenance requires the use of mowers or ditch cleaning equipment. In addition, birds and small animals can become trapped in the netting. Maintenance • Maintain good contact with the ground. Erosion must not occur Standards beneath the net or blanket. • Repair and staple any areas of the net or blanket that are damaged or not in close contact with the ground. • Fix and protect eroded areas if erosion occurs due to poorly controlled drainage. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-24 aIG (300 \ \ (150mm) \ \ Longitudinal Anchor Trench Terminal Slope and Channel Anchor Trench 11 g - Stake at 3'-5' (1-1.5m)intervals. � P � P P � P e P P Check slot at 25'(7.6m)intervals Isometric View P P P 6'(150mm) -W r ) (150mm) Initial Channel Anchor Trench Intermittent Check Slot NOTES: 1.Check slots to be constructed per manufacturers specifications. 2.Staking or stapling layout per manufacturers specifications. Figure 4.1.3—Channel Installation Slope surface shall be smooth before placement for proper soil contact. If there is a berm at the Stapling pattern as per top of slope,anchor manufacturer's recommendations. upslope of the berm. Min.2" Overlap �I I-I I Anchor in 6"x6"min.Trench and staple at 12" intervals. li Min.6"overlap. Ell Staple overlaps III—I 1-1 1-1 I El I l—1 I El . max.5"spacing. Bring material down to a level area,turn Do not stretch blankets/mattings tight- the end under 4"and staple at 12"intervals. allow the rolls to mold to any irregularities. For slopes less than 31-1:1 V,rolls Lime,fertilize,and seed before installation. may be placed in horizontal strips. Planting of shrubs,trees,etc.Should occur after installation. Figure 4.1.4—Slope Installation Volume II— Construction Stormwater Pollution Prevention -December 2014 4-25 BMP C123: Plastic Covering Purpose Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas. Conditions of Plastic covering may be used on disturbed areas that require cover Use measures for less than 30 days, except as stated below. • Plastic is particularly useful for protecting cut and fill slopes and stockpiles. Note: The relatively rapid breakdown of most polyethylene sheeting makes it unsuitable for long-term (greater than six months) applications. • Due to rapid runoff caused by plastic covering, do not use this method upslope of areas that might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes. • Plastic sheeting may result in increased runoff volumes and velocities, requiring additional on-site measures to counteract the increases. Creating a trough with wattles or other material can convey clean water away from these areas. • To prevent undercutting, trench and backfill rolled plastic covering products. • While plastic is inexpensive to purchase, the added cost of installation, maintenance, removal, and disposal make this an expensive material,up to $1.50-2.00 per square yard. • Whenever plastic is used to protect slopes install water collection measures at the base of the slope. These measures include plastic- covered berms, channels, and pipes used to covey clean rainwater away from bare soil and disturbed areas. Do not mix clean runoff from a plastic covered slope with dirty runoff from a project. • Other uses for plastic include: 1. Temporary ditch liner. 2. Pond liner in temporary sediment pond. 3. Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel being stored. 4. Emergency slope protection during heavy rains. 5. Temporary drainpipe ("elephant trunk")used to direct water. Design and • Plastic slope cover must be installed as follows: Installation 1. Run plastic up and down slope, not across slope. Specifications 2. Plastic may be installed perpendicular to a slope if the slope length is less than 10 feet. 3. Minimum of 8-inch overlap at seams. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-26 4. On long or wide slopes, or slopes subject to wind, tape all seams. 5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench at the top of the slope and backfill with soil to keep water from flowing underneath. 6. Place sand filled burlap or geotextile bags every 3 to 6 feet along seams and tie them together with twine to hold them in place. 7. Inspect plastic for rips, tears, and open seams regularly and repair immediately. This prevents high velocity runoff from contacting bare soil which causes extreme erosion. 8. Sandbags may be lowered into place tied to ropes. However, all sandbags must be staked in place. • Plastic sheeting shall have a minimum thickness of 0.06 millimeters. • If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable protection shall be installed at the toe of the slope in order to reduce the velocity of runoff. Maintenance • Torn sheets must be replaced and open seams repaired. Standards • Completely remove and replace the plastic if it begins to deteriorate due to ultraviolet radiation. • Completely remove plastic when no longer needed. • Dispose of old tires used to weight down plastic sheeting appropriately. Approved as Ecology has approved products as able to meet the requirements of BMP Equivalent C 123. The products did not pass through the Technology Assessment Protocol—Ecology(TAPE)process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at http://www.ecy.wa._og_v/programs/wq/stormwater/newtech/equivalent.html BMP C124: Sodding Purpose The purpose of sodding is to establish permanent turf for immediate erosion protection and to stabilize drainage ways where concentrated overland flow will occur. Conditions of Use Sodding may be used in the following areas: • Disturbed areas that require short-term or long-term cover. • Disturbed areas that require immediate vegetative cover. • All waterways that require vegetative lining. Waterways may also be seeded rather than sodded, and protected with a net or blanket. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-27 Design and Sod shall be free of weeds, of uniform thickness (approximately I-inch Installation thick), and shall have a dense root mat for mechanical strength. Specifications The following steps are recommended for sod installation: • Shape and smooth the surface to final grade in accordance with the approved grading plan. The swale needs to be overexcavated 4 to 6 inches below design elevation to allow room for placing soil amendment and sod. • Amend 4 inches (minimum) of compost into the top 8 inches of the soil if the organic content of the soil is less than ten percent or the permeability is less than 0.6 inches per hour. See hqp://www.ecy.wa.goy/programs/swfa/organics/soil.html for further information. • Fertilize according to the supplier's recommendations. • Work lime and fertilizer I to 2 inches into the soil, and smooth the surface. • Lay strips of sod beginning at the lowest area to be sodded and perpendicular to the direction of water flow. Wedge strips securely into place. Square the ends of each strip to provide for a close, tight fit. Stagger joints at least 12 inches. Staple on slopes steeper than 3H:IV. Staple the upstream edge of each sod strip. • Roll the sodded area and irrigate. • When sodding is carried out in alternating strips or other patterns, seed the areas between the sod immediately after sodding. Maintenance If the grass is unhealthy, the cause shall be determined and appropriate Standards action taken to reestablish a healthy groundcover. If it is impossible to establish a healthy groundcover due to frequent saturation, instability, or some other cause, the sod shall be removed, the area seeded with an appropriate mix, and protected with a net or blanket. BMP C125: Topsoiling / Composting Purpose Topsoiling and composting provide a suitable growth medium for final site stabilization with vegetation. While not a permanent cover practice in itself, topsoiling and composting are an integral component of providing permanent cover in those areas where there is an unsuitable soil surface for plant growth. Use this BMP in conjunction with other BMPs such as seeding, mulching, or sodding. Note that this BMP is functionally the same as BMP T5.13 (see Chapter 5 of Volume V of this manual)which is required for all disturbed areas that will be developed as lawn or landscaped areas at the completed project site. Native soils and disturbed soils that have been organically amended not only retain much more stormwater,but they also serve as effective Volume II—Construction Stormwater Pollution Prevention-December 2014 4-28 biofilters for urban pollutants and, by supporting more vigorous plant growth, reduce the water, fertilizer and pesticides needed to support installed landscapes. Topsoil does not include any subsoils but only the material from the top several inches including organic debris. Conditions of • Permanent landscaped areas shall contain healthy topsoil that reduces Use the need for fertilizers, improves overall topsoil quality,provides for better vegetal health and vitality, improves hydrologic characteristics, and reduces the need for irrigation. • Leave native soils and the duff layer undisturbed to the maximum extent practicable. Stripping of existing, properly functioning soil system and vegetation for the purpose of topsoiling during construction is not acceptable. Preserve existing soil systems in undisturbed and uncompacted conditions if functioning properly. • Areas that already have good topsoil, such as undisturbed areas, do not require soil amendments. • Restore, to the maximum extent practical, native soils disturbed during clearing and grading to a condition equal to or better than the original site condition's moisture-holding capacity. Use on-site native topsoil, incorporate amendments into on-site soil, or import blended topsoil to meet this requirement. • Topsoiling is a required procedure when establishing vegetation on shallow soils, and soils of critically low pH (high acid) levels. • Beware of where the topsoil comes from, and what vegetation was on site before disturbance, invasive plant seeds may be included and could cause problems for establishing native plants, landscaped areas, or grasses. • Topsoil from the site will contain mycorrhizal bacteria that are necessary for healthy root growth and nutrient transfer. These native mycorrhiza are acclimated to the site and will provide optimum conditions for establishing grasses. Use commercially available mycorrhiza products when using off-site topsoil. Design and Meet the following requirements for disturbed areas that will be Installation developed as lawn or landscaped areas at the completed project site: Specifications Maximize the depth of the topsoil wherever possible to provide the • maximum possible infiltration capacity and beneficial growth medium. Topsoil shall have: • A minimum depth of 8-inches. Scarify subsoils below the topsoil layer at least 4-inches with some incorporation of the upper material to avoid stratified layers, where feasible. Ripping or re- structuring the subgrade may also provide additional benefits regarding the overall infiltration and interflow dynamics of the soil system. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-29 • A minimum organic content of 10% dry weight in planting beds, and 5% organic matter content in turf areas. Incorporate organic amendments to a minimum 8-inch depth except where tree roots or other natural features limit the depth of incorporation. • A pH between 6.0 and 8.0 or matching the pH of the undisturbed soil. • If blended topsoil is imported, then fines should be limited to 25 percent passing through a 200 sieve. • Mulch planting beds with 2 inches of organic material • Accomplish the required organic content, depth, and pH by returning native topsoil to the site, importing topsoil of sufficient organic content, and/or incorporating organic amendments.When using the option of incorporating amendments to meet the organic content requirement,use compost that meets the compost specification for Bioretention(See BMP T7.30 in Chapter 7 of Volume V of this manual), with the exception that the compost may have up to 35% biosolids or manure. • Sections three through seven of the document entitled, Guidelines and Resources for Implementing Soil Quality and Depth BMP T5.13 in WDOE Stormwater Management Manual for Western Washington, provides useful guidance for implementing whichever option is chosen. It includes guidance for pre-approved default strategies and guidance for custom strategies. Check with your local jurisdiction concerning its acceptance of this guidance. It is available through the organization, Soils for Salmon. As of this printing the document may be found at: hLtp://www.soilsforsalmon.org/pdf/Soil BMP Manuql.pdf. • The final composition and construction of the soil system will result in a natural selection or favoring of certain plant species over time. For example, incorporation of topsoil may favor grasses, while layering with mildly acidic, high-carbon amendments may favor more woody vegetation. • Allow sufficient time in scheduling for topsoil spreading prior to seeding, sodding, or planting. • Take care when applying top soil to subsoils with contrasting textures. Sandy topsoil over clayey subsoil is a particularly poor combination, as water creeps along the junction between the soil layers and causes the topsoil to slough. If topsoil and subsoil are not properly bonded, water will not infiltrate the soil profile evenly and it will be difficult to establish vegetation. The best method to prevent a lack of bonding is to actually work the topsoil into the layer below for a depth of at least 6 inches. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-30 • Field exploration of the site shall be made to determine if there is surface soil of sufficient quantity and quality to justify stripping. Topsoil shall be friable and loamy(loam, sandy loam, silt loam, sandy clay loam, and clay loam). Avoid areas of natural ground water recharge. • Stripping shall be confined to the immediate construction area. A 4- inch to 6-inch stripping depth is common, but depth may vary depending on the particular soil. All surface runoff control structures shall be in place prior to stripping. • Do not place topsoil while in a frozen or muddy condition, when the subgrade is excessively wet, or when conditions exist that may otherwise be detrimental to proper grading or proposed sodding or seeding. • In any areas requiring grading remove and stockpile the duff layer and topsoil on site in a designated, controlled area, not adjacent to public resources and critical areas. Stockpiled topsoil is to be reapplied to other portions of the site where feasible. • Locate the topsoil stockpile so that it meets specifications and does not interfere with work on the site. It may be possible to locate more than one pile in proximity to areas where topsoil will be used. Stockpiling of topsoil shall occur in the following manner: • Side slopes of the stockpile shall not exceed 2H:1 V. • Between October 1 and April 30: • An interceptor dike with gravel outlet and silt fence shall surround all topsoil. • Within 2 days complete erosion control seeding, or covering stockpiles with clear plastic, or other mulching materials. • Between May 1 and September 30: • An interceptor dike with gravel outlet and silt fence shall surround all topsoil if the stockpile will remain in place for a longer period of time than active construction grading. • Within 7 days complete erosion control seeding, or covering stockpiles with clear plastic, or other mulching materials. • When native topsoil is to be stockpiled and reused the following should apply to ensure that the mycorrhizal bacterial, earthworms, and other beneficial organisms will not be destroyed: 1. Re-install topsoil within 4 to 6 weeks. 2. Do not allow the saturation of topsoil with water. 3. Do not use plastic covering. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-31 Maintenance • Inspect stockpiles regularly, especially after large storm events. Standards Stabilize any areas that have eroded. • Establish soil quality and depth toward the end of construction and once established, protect from compaction, such as from large machinery use, and from erosion. • Plant and mulch soil after installation. • Leave plant debris or its equivalent on the soil surface to replenish organic matter. • Reduce and adjust, where possible, the use of irrigation, fertilizers, herbicides and pesticides, rather than continuing to implement formerly established practices. BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection Purpose Polyacrylamide (PAM) is used on construction sites to prevent soil erosion. Applying PAM to bare soil in advance of a rain event significantly reduces erosion and controls sediment in two ways. First, PAM increases the soil's available pore volume, thus increasing infiltration through flocculation and reducing the quantity of stormwater runoff. Second, it increases flocculation of suspended particles and aids in their deposition, thus reducing stormwater runoff turbidity and improving water quality. Conditions of Use PAM shall not be directly applied to water or allowed to enter a water body. In areas that drain to a sediment pond, PAM can be applied to bare soil under the following conditions: • During rough grading operations. • In Staging areas. • Balanced cut and fill earthwork. • Haul roads prior to placement of crushed rock surfacing. • Compacted soil roadbase. • Stockpiles. • After final grade and before paving or final seeding and planting. • Pit sites. • Sites having a winter shut down. In the case of winter shut down, or where soil will remain unworked for several months, PAM should be used together with mulch. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-32 Design and PAM may be applied with water in dissolved form. The preferred Installation application method is the dissolved form. Specifications PAM is to be applied at a maximum rate of 2/3 pound PAM per 1,000 gallons water(80 mg/L)per 1 acre of bare soil. Table 4.1.9 can be used to determine the PAM and water application rate for a disturbed soil area. Higher concentrations of PAM do not provide any additional effectiveness. Table 4.1.9 PAM and Water Application Rates Disturbed Area(ac) PAM(lbs) Water(gal) 0.50 0.33 500 1.00 0.66 1,000 1.50 1.00 1,500 2.00 1.32 2,000 2.50 1.65 2,500 3.00 2.00 3,000 3.50 2.33 3,500 4.00 2.65 4,000 4.50 3.00 4,500 5.00 3.33 5,000 The Preferred Method: • Pre-measure the area where PAM is to be applied and calculate the amount of product and water necessary to provide coverage at the specified application rate (2/3 pound PAM/1000 gallons/acre). • PAM has infinite solubility in water, but dissolves very slowly. Dissolve pre-measured dry granular PAM with a known quantity of clean water in a bucket several hours or overnight. Mechanical mixing will help dissolve the PAM. Always add PAM to water-not water to PAM. • Pre-fill the water truck about 1/8 full with water. The water does not have to be potable, but it must have relatively low turbidity—in the range of 20 NTU or less. • Add PAM/Water mixture to the truck • Completely fill the water truck to specified volume. • Spray PAM/Water mixture onto dry soil until the soil surface is uniformly and completely wetted. An Alternate Method: PAM may also be applied as a powder at the rate of 5 lbs. per acre. This must be applied on a day that is dry. For areas less than 5-10 acres, a hand- held"organ grinder" fertilizer spreader set to the smallest setting will work. Tractor-mounted spreaders will work for larger areas. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-33 The following shall be used for application of powdered PAM: • Powered PAM shall be used in conjunction with other BMPs and not in place of other BMPs. • Do not use PAM on a slope that flows directly into a stream or wetland. The stormwater runoff shall pass through a sediment control BMP prior to discharging to surface waters. • Do not add PAM to water discharging from site. • When the total drainage area is greater than or equal to 5 acres, PAM treated areas shall drain to a sediment pond. • Areas less than 5 acres shall drain to sediment control BMPs, such as a minimum of 3 check dams per acre. The total number of check dams used shall be maximized to achieve the greatest amount of settlement of sediment prior to discharging from the site. Each check dam shall be spaced evenly in the drainage channel through which stormwater flows are discharged off-site. • On all sites, the use of silt fence shall be maximized to limit the discharges of sediment from the site. • All areas not being actively worked shall be covered and protected from rainfall. PAM shall not be the only cover BMP used. • PAM can be applied to wet soil, but dry soil is preferred due to less sediment loss. • PAM will work when applied to saturated soil but is not as effective as applications to dry or damp soil. • Keep the granular PAM supply out of the sun. Granular PAM loses its effectiveness in three months after exposure to sunlight and air. • Proper application and re-application plans are necessary to ensure total effectiveness of PAM usage. • PAM, combined with water, is very slippery and can be a safety hazard. Care must be taken to prevent spills of PAM powder onto paved surfaces. During an application of PAM, prevent over-spray from reaching pavement as pavement will become slippery. If PAM powder gets on skin or clothing, wipe it off with a rough towel rather than washing with water-this only makes cleanup messier and take longer. • Some PAMs are more toxic and carcinogenic than others. Only the most environmentally safe PAM products should be used. The specific PAM copolymer formulation must be anionic. Cationic PAM shall not be used in any application because of known aquatic toxicity problems. Only the highest drinking water grade PAM, certified for compliance with ANSUNSF Standard 60 for Volume II—Construction Stormwater Pollution Prevention -December 2014 4-34 drinking water treatment, will be used for soil applications. Recent media attention and high interest in PAM has resulted in some entrepreneurial exploitation of the term "polymer." All PAM are polymers, but not all polymers are PAM, and not all PAM products comply with ANSI/NSF Standard 60. PAM use shall be reviewed and approved by the local permitting authority. • PAM designated for these uses should be "water soluble" or "linear" or "non-crosslinked". Cross-linked or water absorbent PAM, polymerized in highly acidic (pH<2) conditions, are used to maintain soil moisture content. • The PAM anionic charge density may vary from 2-30 percent; a value of 18 percent is typical. Studies conducted by the United States Department of Agriculture (USDA)/ARS demonstrated that soil stabilization was optimized by using very high molecular weight (12- 15 mg/mole), highly anionic (>20%hydrolysis) PAM. • PAM tackifiers are available and being used in place of guar and alpha plantago. Typically, PAM tackifiers should be used at a rate of no more than 0.5-1 lb. per 1000 gallons of water in a hydromulch machine. Some tackifier product instructions say to use at a rate of 3 —5 lbs. per acre, which can be too much. In addition,pump problems can occur at higher rates due to increased viscosity. Maintenance • PAM may be reapplied on actively worked areas after a 48-hour Standards period. • Reapplication is not required unless PAM treated soil is disturbed or unless turbidity levels show the need for an additional application. If PAM treated soil is left undisturbed a reapplication may be necessary after two months. More PAM applications may be required for steep slopes, silty and clayey soils (USDA Classification Type "C" and "D" soils), long grades, and high precipitation areas. When PAM is applied first to bare soil and then covered with straw, a reapplication may not be necessary for several months. • Loss of sediment and PAM may be a basis for penalties per RCW 90.48.080. BMP C130: Surface Roughening Purpose Surface roughening aids in the establishment of vegetative cover, reduces runoff velocity, increases infiltration, and provides for sediment trapping through the provision of a rough soil surface. Horizontal depressions are created by operating a tiller or other suitable equipment on the contour or by leaving slopes in a roughened condition by not fine grading them. Use this BMP in conjunction with other BMPs such as seeding, mulching, or sodding. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-35 Conditions for • All slopes steeper than 3H:1 V and greater than 5 vertical feet Use require surface roughening to a depth of 2 to 4 inches prior to seeding.. • Areas that will not be stabilized immediately may be roughened to reduce runoff velocity until seeding takes place. • Slopes with a stable rock face do not require roughening. • Slopes where mowing is planned should not be excessively roughened. Design and There are different methods for achieving a roughened soil surface on a Installation slope, and the selection of an appropriate method depends upon the type of Specifications slope. Roughening methods include stair-step grading, grooving, contour furrows, and tracking. See Figure 4.1.5 for tracking and contour furrows. Factors to be considered in choosing a method are slope steepness, mowing requirements, and whether the slope is formed by cutting or filling. • Disturbed areas that will not require mowing may be stair-step graded, grooved, or left rough after filling. • Stair-step grading is particularly appropriate in soils containing large amounts of soft rock. Each "step" catches material that sloughs from above, and provides a level site where vegetation can become established. Stairs should be wide enough to work with standard earth moving equipment. Stair steps must be on contour or gullies will form on the slope. • Areas that will be mowed(these areas should have slopes less steep than 3H:IV)may have small furrows left by disking, harrowing, raking, or seed-planting machinery operated on the contour. • Graded areas with slopes steeper than 3H:IV but less than 2H:I V should be roughened before seeding. This can be accomplished in a variety of ways, including "track walking," or driving a crawler tractor up and down the slope, leaving a pattern of cleat imprints parallel to slope contours. • Tracking is done by operating equipment up and down the slope to leave horizontal depressions in the soil. Maintenance • Areas that are graded in this manner should be seeded as quickly as Standards possible. • Regular inspections should be made of the area. If rills appear, they should be re-graded and re-seeded immediately. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-36 Tracking 10 e e.e e ee ee 88ee. � �ee � � e e� eeeee ee ee e � e ee e ee ee e e e o 88 e e e e e e e e 'TRACKING'with machinery up and down the slope provides grooves that will catch seed,rainfall and reduce runoff. \ e e e Contour Furrows (15, 6"min (150mm) \\\\\ 3 Maximum Grooves Will Catch Seed, Fertilizer, and Decrease Rainfall e Runoff. /\ / X//\� Figure 4.1.5—Surface Roughening by Tracking and Contour Furrows Volume II—Construction Stormwater Pollution Prevention -December 2014 4-37 BMP C131: Gradient Terraces Purpose Gradient terraces reduce erosion damage by intercepting surface runoff and conducting it to a stable outlet at a non-erosive velocity. Conditions of Use Gradient terraces normally are limited to denuded land having a water erosion problem. They should not be constructed on deep sands or on soils that are too stony, steep, or shallow to permit practical and economical installation and maintenance. Gradient terraces may be used only where suitable outlets are or will be made available. See Figure 4.1.6 for gradient terraces. Design and The maximum vertical spacing of gradient terraces should be Installation determined by the following method: Specifications VI = (0.8)s+y Where: VI =vertical interval in feet s = land rise per 100 feet, expressed in feet y =a soil and cover variable with values from 1.0 to 4.0 Values of"y" are influenced by soil erodibility and cover practices. The lower values are applicable to erosive soils where little to no residue is left on the surface. The higher value is applicable only to erosion-resistant soils where a large amount of residue (I1/2 tons of straw/acre equivalent) is on the surface. • The minimum constructed cross-section should meet the design dimensions. • The top of the constructed ridge should not be lower at any point than the design elevation plus the specified overfill for settlement. The opening at the outlet end of the terrace should have a cross section equal to that specified for the terrace channel. • Channel grades may be either uniform or variable with a maximum grade of 0.6 feet per 100 feet length (0.6%). For short distances, terrace grades may be increased to improve alignment. The channel velocity should not exceed that which is nonerosive for the soil type. • All gradient terraces should have adequate outlets. Such an outlet may be a grassed waterway, vegetated area, or tile outlet. In all cases the outlet must convey runoff from the terrace or terrace system to a point where the outflow will not cause damage. Vegetative cover should be used in the outlet channel. • The design elevation of the water surface of the terrace should not be lower than the design elevation of the water surface in the outlet at their junction, when both are operating at design flow. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-38 • Vertical spacing determined by the above methods may be increased as much as 0.5 feet or 10 percent, whichever is greater, to provide better alignment or location, to avoid obstacles, to adjust for equipment size, or to reach a satisfactory outlet. The drainage area above the terrace should not exceed the area that would be drained by a terrace with normal spacing. • The terrace should have enough capacity to handle the peak runoff expected from a 2-year, 24-hour design storm without overtopping. • The terrace cross-section should be proportioned to fit the land slope. The ridge height should include a reasonable settlement factor. The ridge should have a minimum top width of 3 feet at the design height. The minimum cross-sectional area of the terrace channel should be 8 square feet for land slopes of 5 percent or less, 7 square feet for slopes from 5 to 8 percent, and 6 square feet for slopes steeper than 8 percent. The terrace can be constructed wide enough to be maintained using a small vehicle. Maintenance • Maintenance should be performed as needed. Terraces should be Standards inspected regularly; at least once a year, and after large storm events. Slope to adequate outlet. 10' min. i 0* ��1 �\ly��I' � I 60''�, a Figure 4.1.6—Gradient Terraces Volume II—Construction Stormwater Pollution Prevention -December 2014 4-39 BMP C140: Dust Control Purpose Dust control prevents wind transport of dust from disturbed soil surfaces onto roadways, drainage ways, and surface waters. Conditions of'Use • In areas (including roadways) subject to surface and air movement of dust where on-site and off-site impacts to roadways, drainage ways, or surface waters are likely. Design and • Vegetate or mulch areas that will not receive vehicle traffic. In areas Installation where planting, mulching, or paving is impractical, apply gravel or Specifications landscaping rock. • Limit dust generation by clearing only those areas where immediate activity will take place, leaving the remaining area(s) in the original condition. Maintain the original ground cover as long as practical. • Construct natural or artificial windbreaks or windscreens. These may be designed as enclosures for small dust sources. • Sprinkle the site with water until surface is wet. Repeat as needed. To prevent carryout of mud onto street, refer to Stabilized Construction Entrance (BMP C 105). • Irrigation water can be used for dust control. Irrigation systems should be installed as a first step on sites where dust control is a concern. • Spray exposed soil areas with a dust palliative, following the manufacturer's instructions and cautions regarding handling and application. Used oil is prohibited from use as a dust suppressant. Local governments may approve other dust palliatives such as calcium chloride or PAM. • PAM (BMP C126) added to water at a rate of 0.5 lbs. per 1,000 gallons of water per acre and applied from a water truck is more effective than water alone. This is due to increased infiltration of water into the soil and reduced evaporation. In addition, small soil particles are bonded together and are not as easily transported by wind. Adding PAM may actually reduce the quantity of water needed for dust control. Use of PAM could be a cost-effective dust control method. Techniques that can be used for unpaved roads and lots include: • Lower speed limits. High vehicle speed increases the amount of dust stirred up from unpaved roads and lots. • Upgrade the road surface strength by improving particle size, shape, and mineral types that make up the surface and base materials. • Add surface gravel to reduce the source of dust emission. Limit the amount of fine particles (those smaller than .075 mm) to 10 to 20 percent. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-40 • Use geotextile fabrics to increase the strength of new roads or roads undergoing reconstruction. • Encourage the use of alternate,paved routes, if available. • Restrict use of paved roadways by tracked vehicles and heavy trucks to prevent damage to road surface and base. • Apply chemical dust suppressants using the admix method,blending the product with the top few inches of surface material. Suppressants may also be applied as surface treatments. • Pave unpaved permanent roads and other trafficked areas. • Use vacuum street sweepers. • Remove mud and other dirt promptly so it does not dry and then turn into dust. • Limit dust-causing work on windy days. • Contact your local Air Pollution Control Authority for guidance and training on other dust control measures. Compliance with the local Air Pollution Control Authority constitutes compliance with this BMP. Maintenance Respray area as necessary to keep dust to a minimum. Standards BMP C150: Materials on Hand Purpose Keep quantities of erosion prevention and sediment control materials on the project site at all times to be used for regular maintenance and emergency situations such as unexpected heavy summer rains. Having these materials on-site reduces the time needed to implement BMPs when inspections indicate that existing BMPs are not meeting the Construction SWPPP requirements. In addition, contractors can save money by buying some materials in bulk and storing them at their office or yard. Conditions of Use Construction projects of any size or type can benefit from having materials on hand. A small commercial development project could have a roll of plastic and some gravel available for immediate protection of bare soil and temporary berm construction. A large earthwork project, such as highway construction, might have several tons of straw, several rolls of plastic, flexible pipe, sandbags, geotextile fabric and steel "T"posts. • Materials are stockpiled and readily available before any site clearing, grubbing, or earthwork begins. A large contractor or developer could keep a stockpile of materials that are available for use on several projects. • If storage space at the project site is at a premium, the contractor could maintain the materials at their office or yard. The office or yard must be less than an hour from the project site. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-41 Design and Depending on project type, size, complexity, and length, materials and Installation quantities will vary. A good minimum list of items that will cover Specifications numerous situations includes: Material Clear Plastic, 6 mil Drainpipe, 6 or 8 inch diameter Sandbags, filled Straw Bales for mulching, Quarry Spalls Washed Gravel Geotextile Fabric Catch Basin Inserts Steel "T"Posts Silt fence material Straw Wattles Maintenance • All materials with the exception of the quarry spalls, steel "T"posts, Standards and gravel should be kept covered and out of both sun and rain. • Re-stock materials used as needed. BMP C151: Concrete Handling Purpose Concrete work can generate process water and slurry that contain fine particles and high pH, both of which can violate water quality standards in the receiving water. Concrete spillage or concrete discharge to surface waters of the State is prohibited. Use this BMP to minimize and eliminate concrete, concrete process water, and concrete slurry from entering waters of the state. Conditions of Use Any time concrete is used, utilize these management practices. Concrete construction projects include, but are not limited to, the following: • Curbs • Sidewalks • Roads • Bridges • Foundations • Floors • Runways Design and Assure that washout of concrete trucks, chutes,pumps, and internals is Installation performed at an approved off-site location or in designated concrete Volume II—Construction Stormwater Pollution Prevention -December 2014 4-42 Specifications washout areas. Do not wash out concrete trucks onto the ground, or into storm drains, open ditches, streets, or streams. Refer to BMP C 154 for information on concrete washout areas. • Return unused concrete remaining in the truck and pump to the originating batch plant for recycling. Do not dump excess concrete on site, except in designated concrete washout areas. • Wash off hand tools including, but not limited to, screeds, shovels, rakes, floats, and trowels into formed areas only. • Wash equipment difficult to move, such as concrete pavers in areas that do not directly drain to natural or constructed stormwater conveyances. • Do not allow washdown from areas, such as concrete aggregate driveways, to drain directly to natural or constructed stormwater conveyances. • Contain washwater and leftover product in a lined container when no formed areas are available. Dispose of contained concrete in a manner that does not violate ground water or surface water quality standards. • Always use forms or solid barriers for concrete pours, such as pilings, within 15-feet of surface waters. • Refer to BMPs C252 and C253 for pH adjustment requirements. • Refer to the Construction Stormwater General Permit for pH monitoring requirements if the project involves one of the following activities: • Significant concrete work(greater than 1,000 cubic yards poured concrete or recycled concrete used over the life of a project). • The use of engineered soils amended with(but not limited to) Portland cement-treated base, cement kiln dust or fly ash. • Discharging stormwater to segments of water bodies on the 303(d) list(Category 5) for high pH. Maintenance Check containers for holes in the liner daily during concrete pours and Standards repair the same day. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-43 BMP C152: Sawcutting and Surfacing Pollution Prevention Purpose Sawcutting and surfacing operations generate slurry and process water that contains fine particles and high pH (concrete cutting),both of which can violate the water quality standards in the receiving water. Concrete spillage or concrete discharge to surface waters of the State is prohibited. Use this BMP to minimize and eliminate process water and slurry created through sawcutting or surfacing from entering waters of the State. Conditions of Use Utilize these management practices anytime sawcutting or surfacing operations take place. Sawcutting and surfacing operations include,but are not limited to, the following: • Sawing • Coring • Grinding • Roughening • Hydro-demolition • Bridge and road surfacing Design and • Vacuum slurry and cuttings during cutting and surfacing operations. Installation Slurry and cuttings shall not remain on permanent concrete or asphalt Specifications pavement overnight. • Slurry and cuttings shall not drain to any natural or constructed drainage conveyance including stormwater systems. This may require temporarily blocking catch basins. • Dispose of collected slurry and cuttings in a manner that does not violate ground water or surface water quality standards. • Do not allow process water generated during hydro-demolition, surface roughening or similar operations to drain to any natural or constructed drainage conveyance including stormwater systems. Dispose process water in a manner that does not violate ground water or surface water quality standards. • Handle and dispose cleaning waste material and demolition debris in a manner that does not cause contamination of water. Dispose of sweeping material from a pick-up sweeper at an appropriate disposal site. Maintenance Continually monitor operations to determine whether slurry, cuttings, or Standards process water could enter waters of the state. If inspections show that a violation of water quality standards could occur, stop operations and immediately implement preventive measures such as berms,barriers, secondary containment, and vacuum trucks. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-44 BMP C153: Material Delivery, Storage and Containment Purpose Prevent, reduce, or eliminate the discharge of pollutants to the stormwater system or watercourses from material delivery and storage. Minimize the storage of hazardous materials on-site, store materials in a designated area, and install secondary containment. Conditions of Use These procedures are suitable for use at all construction sites with delivery and storage of the following materials: • Petroleum products such as fuel, oil and grease • Soil stabilizers and binders (e.g., Polyacrylamide) • Fertilizers, pesticides and herbicides • Detergents • Asphalt and concrete compounds • Hazardous chemicals such as acids, lime, adhesives,paints, solvents, and curing compounds • Any other material that may be detrimental if released to the environment Design and The following steps should be taken to minimize risk: Installation Temporary storage area should be located away from vehicular traffic, Specifications near the construction entrance(s), and away from waterways or storm drains. • Material Safety Data Sheets (MSDS) should be supplied for all materials stored. Chemicals should be kept in their original labeled containers. • Hazardous material storage on-site should be minimized. • Hazardous materials should be handled as infrequently as possible. • During the wet weather season(Oct I —April 30), consider storing materials in a covered area. • Materials should be stored in secondary containments, such as earthen dike, horse trough, or even a children's wading pool for non-reactive materials such as detergents, oil, grease, and paints. Small amounts of material may be secondarily contained in"bus boy"trays or concrete mixing trays. • Do not store chemicals, drums, or bagged materials directly on the ground. Place these items on a pallet and, when possible, and within secondary containment. • If drums must be kept uncovered, store them at a slight angle to reduce ponding of rainwater on the lids to reduce corrosion. Domed plastic covers are inexpensive and snap to the top of drums, preventing water from collecting. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-45 Material Storage Areas and Secondary Containment Practices: • Liquids, petroleum products, and substances listed in 40 CFR Parts 110, 117, or 302 shall be stored in approved containers and drums and shall not be overfilled. Containers and drums shall be stored in temporary secondary containment facilities. • Temporary secondary containment facilities shall provide for a spill containment volume able to contain 10% of the total enclosed container volume of all containers, or 110% of the capacity of the largest container within its boundary, whichever is greater. • Secondary containment facilities shall be impervious to the materials stored therein for a minimum contact time of 72 hours. • Secondary containment facilities shall be maintained free of accumulated rainwater and spills. In the event of spills or leaks, accumulated rainwater and spills shall be collected and placed into drums. These liquids shall be handled as hazardous waste unless testing determines them to be non-hazardous. • Sufficient separation should be provided between stored containers to allow for spill cleanup and emergency response access. • During the wet weather season(Oct 1 —April 30), each secondary containment facility shall be covered during non-working days,prior to and during rain events. • Keep material storage areas clean, organized and equipped with an ample supply of appropriate spill clean-up material (spill kit). • The spill kit should include, at a minimum: • I-Water Resistant Nylon Bag • 3-Oil Absorbent Socks 3"x 4' • 2-Oil Absorbent Socks 3"x 10' • 12-Oil Absorbent Pads 17"x19" • 1-Pair Splash Resistant Goggles • 3-Pair Nitrile Gloves • 10-Disposable Bags with Ties • Instructions Volume II—Construction Stormwater Pollution Prevention -December 2014 4-46 BMP C154: Concrete Washout Area Purpose Prevent or reduce the discharge of pollutants to stormwater from concrete waste by conducting washout off-site, or performing on-site washout in a designated area to prevent pollutants from entering surface waters or ground water. Conditions of Use Concrete washout area best management practices are implemented on construction projects where: • Concrete is used as a construction material • It is not possible to dispose of all concrete wastewater and washout off-site (ready mix plant, etc.). • Concrete trucks, pumpers, or other concrete coated equipment are washed on-site. • Note: If less than 10 concrete trucks or pumpers need to be washed out on-site, the washwater may be disposed of in a formed area awaiting concrete or an upland disposal site where it will not contaminate surface or ground water. The upland disposal site shall be at least 50 feet from sensitive areas such as storm drains, open ditches, or water bodies, including wetlands. Design and Implementation Installation The following steps will help reduce stormwater pollution from concrete Specifications wastes: • Perform washout of concrete trucks at an approved off-site location or in designated concrete washout areas only. • Do not wash out concrete trucks onto the ground, or into storm drains, open ditches, streets, or streams. • Do not allow excess concrete to be dumped on-site, except in designated concrete washout areas. • Concrete washout areas may be prefabricated concrete washout containers, or self-installed structures (above-grade or below-grade). • Prefabricated containers are most resistant to damage and protect against spills and leaks. Companies may offer delivery service and provide regular maintenance and disposal of solid and liquid waste. • If self-installed concrete washout areas are used, below-grade structures are preferred over above-grade structures because they are less prone to spills and leaks. • Self-installed above-grade structures should only be used if excavation is not practical. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-47 Education • Discuss the concrete management techniques described in this BMP with the ready-mix concrete supplier before any deliveries are made. • Educate employees and subcontractors on the concrete waste management techniques described in this BMP. • Arrange for contractor's superintendent or Certified Erosion and Sediment Control Lead(CESCL)to oversee and enforce concrete waste management procedures. • A sign should be installed adjacent to each temporary concrete washout facility to inform concrete equipment operators to utilize the proper facilities. Contracts Incorporate requirements for concrete waste management into concrete supplier and subcontractor agreements. Location and Placement • Locate washout area at least 50 feet from sensitive areas such as storm drains, open ditches, or water bodies, including wetlands. • Allow convenient access for concrete trucks,preferably near the area where the concrete is being poured. • If trucks need to leave a paved area to access washout, prevent track- out with a pad of rock or quarry spalls (see BMP C 105). These areas should be far enough away from other construction traffic to reduce the likelihood of accidental damage and spills. • The number of facilities you install should depend on the expected demand for storage capacity. • On large sites with extensive concrete work, washouts should be placed in multiple locations for ease of use by concrete truck drivers. On-site Temporary Concrete Washout Facility, Transit Truck Washout Procedures: • Temporary concrete washout facilities shall be located a minimum of 50 ft from sensitive areas including storm drain inlets, open drainage facilities, and watercourses. See Figures 4.1.7 and 4.1.8. • Concrete washout facilities shall be constructed and maintained in sufficient quantity and size to contain all liquid and concrete waste generated by washout operations. • Washout of concrete trucks shall be performed in designated areas only. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-48 • Concrete washout from concrete pumper bins can be washed into concrete pumper trucks and discharged into designated washout area or properly disposed of off-site. • Once concrete wastes are washed into the designated area and allowed to harden, the concrete should be broken up, removed, and disposed of per applicable solid waste regulations. Dispose of hardened concrete on a regular basis. • Temporary Above-Grade Concrete Washout Facility • Temporary concrete washout facility(type above grade) should be constructed as shown on the details below, with a recommended minimum length and minimum width of 10 ft, but with sufficient quantity and volume to contain all liquid and concrete waste generated by washout operations. • Plastic lining material should be a minimum of 10 mil polyethylene sheeting and should be free of holes, tears, or other defects that compromise the impermeability of the material. • Temporary Below-Grade Concrete Washout Facility • Temporary concrete washout facilities (type below grade) should be constructed as shown on the details below, with a recommended minimum length and minimum width of 10 ft. The quantity and volume should be sufficient to contain all liquid and concrete waste generated by washout operations. • Lath and flagging should be commercial type. • Plastic lining material shall be a minimum of 10 mil polyethylene sheeting and should be free of holes, tears, or other defects that compromise the impermeability of the material. • Liner seams shall be installed in accordance with manufacturers' recommendations. • Soil base shall be prepared free of rocks or other debris that may cause tears or holes in the plastic lining material. Maintenance Inspection and Maintenance Standards • Inspect and verify that concrete washout BMPs are in place prior to the commencement of concrete work. • During periods of concrete work, inspect daily to verify continued performance. • Check overall condition and performance. • Check remaining capacity(% full). • If using self-installed washout facilities, verify plastic liners are intact and sidewalls are not damaged. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-49 • If using prefabricated containers, check for leaks. • Washout facilities shall be maintained to provide adequate holding capacity with a minimum freeboard of 12 inches. • Washout facilities must be cleaned, or new facilities must be constructed and ready for use once the washout is 75% full. • If the washout is nearing,capacity, vacuum and dispose of the waste material in an approved manner. • Do not discharge liquid or slurry to waterways, storm drains or directly onto ground. • Do not use sanitary sewer without local approval. • Place a secure, non-collapsing, non-water collecting cover over the concrete washout facility prior to predicted wet weather to prevent accumulation and overflow of precipitation. • Remove and dispose of hardened concrete and return the structure to a functional condition. Concrete may be reused on-site or hauled away for disposal or recycling. • When you remove materials from the self-installed concrete washout, build a new structure; or, if the previous structure is still intact, inspect for signs of weakening or damage, and make any necessary repairs. Re-line the structure with new plastic after each cleaning. Removal of Temporary Concrete Washout Facilities • When temporary concrete washout facilities are no longer required for the work, the hardened concrete, slurries and liquids shall be removed and properly disposed of. • Materials used to construct temporary concrete washout facilities shall be removed from the site of the work and disposed of or recycled. • Holes, depressions or other ground disturbance caused by the removal of the temporary concrete washout facilities shall be backfilled, repaired, and stabilized to prevent erosion. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-50 SANDBAG 10 mP PLASTIC LINRIG 10 mil PLASTIC LINING 1 m WOOD FRAME SECURELY ' FASTENED AROUND BERM ENTIRE PERIMETER WITH TWO STAKES LATH AND NOT TO SCALE FLAGGING ON yECIpN Y-B' 3 SDES NOT TO SCALE 31, MINIMUM O O TWO-STA (ED O O 21112 ROUGH 3m MINIMUM ►{ WOOD FRAME 0 B B' A A' VARIES O VARIES STAKE (TYP.) O /.. O O O SANDBAG-` 10 mil PLASTIC LINING; 10 mil PLASTIC LINING NOT TO SCALE BFRM HOT TO SCALE TYPE 'BELOW GRADE' TYPE 'ABOVE GRADE' NOTES: WITH WOOD PLANKS 1. ACTUAL LAYOUT DETERMINED IN THE FIELD. 2. THE CONCRETE WASHOUT SIGN (SEE PAGE 6) SHALL BE INSTALLED WITHIN 10 m OF THE TEMPORARY CONCRETE WASHOUT FACIUTY. Figure 4.1.7a—Concrete Washout Area Volume II—Construction Stormwater Pollution Prevention -December 2014 4-51 STRAW BALE STAPLES BINDING WIRE (2 PER BALE) 10 mil PLASTIC LINING WOOD OR METAL NATIVE MATERIAL STAKES(2 PER BALE) (OPTIONAL) SECTKW B-B' NOT TO SCALE PLYWOOD 1200 mm x610 mm 3m MINIMUM ► STAKE PAINTED WHITE (TYP-) I!CONCRETE j i =_BLACK LETTERS ��WASHOUTl� 150 mm HEIGHT __LAG SCREWS 915 mm (12.5 mm) B B. WOOD POST 915 m�m (89 mm x 89 mm x 2.4 m) VARIES I CONCRETE WASHOUT SIGN DETAIL (OR EQUIVALENT) ■ ■ ■ ■ ■ sa STRAW BALE 200 mm 1^� 3.05 mm DIA. 10 mil PLASTIC LINING (TYp.) I I� STEEL WIRE NOT TO SCAIF TYPE ABOVE GRADE' STAPLE DETAIL WITH STRAW BALES H4ffi 1. ACTUAL LAYOUT DETERMINED IN THE FIELD. 2. THE CONCRETE WASHOUT SIGN (SEE FIG. 4-1S) SHALL BE INSTALLED WITHIN 10 In OF THE TEMPORARY CONCRETE WASHOUT FACIUTTY. C. N15/FCA-14.01N0 W 8-14-02 Figure 4.1.7b—Concrete Washout Area Figure 4.1.8— Prefabricated Concrete Washout Container w/Ramp Volume II— Construction Stormwater Pollution Prevention -December 2014 4-52 BMP C160: Certified Erosion and Sediment Control Lead Purpose The project proponent designates at least one person as the responsible representative in charge of erosion and sediment control (ESC), and water quality protection. The designated person shall be the Certified Erosion and Sediment Control Lead(CESCL)who is responsible for ensuring compliance with all local, state, and federal erosion and sediment control and water quality requirements. Conditions of Use A CESCL shall be made available on projects one acre or larger that discharge stormwater to surface waters of the state. Sites less than one acre may have a person without CESCL certification conduct inspections; sampling is not required on sites that disturb less than an acre. • The CESCL shall: • Have a current certificate proving attendance in an erosion and sediment control training course that meets the minimum ESC training and certification requirements established by Ecology(see details below). Ecology will maintain a list of ESC training and certification providers at: hLtp://www.ecy.wa.goy/programs/wq/storinwater/cescl.html OR • Be a Certified Professional in Erosion and Sediment Control (CPESC); for additional information go to: www.cpesc.net Specifications • Certification shall remain valid for three years. • The CESCL shall have authority to act on behalf of the contractor or developer and shall be available, or on-call, 24 hours per day throughout the period of construction. • The Construction SWPPP shall include the name, telephone number, fax number, and address of the designated CESCL. • A CESCL may provide inspection and compliance services for multiple construction projects in the same geographic region. Duties and responsibilities of the CESCL shall include, but are not limited to the following: • Maintaining permit file on site at all times which includes the Construction SWPPP and any associated permits and plans. • Directing BMP installation, inspection, maintenance, modification, and removal. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-53 • Updating all project drawings and the Construction SWPPP with changes made. • Completing any sampling requirements including reporting results using WebDMR. • Keeping daily logs, and inspection reports. Inspection reports should include: • Inspection date/time. • Weather information; general conditions during inspection and approximate amount of precipitation since the last inspection. • A summary or list of all BMPs implemented, including observations of all erosion/sediment control structures or practices. The following shall be noted: 1. Locations of BMPs inspected. 2. Locations of BMPs that need maintenance. 3. Locations of BMPs that failed to operate as designed or intended. 4. Locations of where additional or different BMPs are required. • Visual monitoring results, including a description of discharged stormwater. The presence of suspended sediment, turbid water, discoloration, and oil sheen shall be noted, as applicable. • Any water quality monitoring performed during inspection. • General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. • Facilitate, participate in, and take corrective actions resulting from inspections performed by outside agencies or the owner. BMP C162: Scheduling Purpose Sequencing a construction project reduces the amount and duration of soil exposed to erosion by wind, rain, runoff, and vehicle tracking. Conditions of Use The construction sequence schedule is an orderly listing of all major land- disturbing activities together with the necessary erosion and sedimentation control measures planned for the project. This type of schedule guides the contractor on work to be done before other work is started so that serious erosion and sedimentation problems can be avoided. Following a specified work schedule that coordinates the timing of land- disturbing activities and the installation of control measures is perhaps the most cost-effective way of controlling erosion during construction. The removal of surface ground cover leaves a site vulnerable to accelerated Volume II—Construction Stormwater Pollution Prevention -December 2014 4-54 erosion. Construction procedures that limit land clearing provide timely installation of erosion and sedimentation controls, and restore protective cover quickly can significantly reduce the erosion potential of a site. Design Minimize construction during rainy periods. Considerations Schedule projects to disturb only small portions of the site at any one • time. Complete grading as soon as possible. Immediately stabilize the disturbed portion before grading the next portion. Practice staged seeding in order to revegetate cut and fill slopes as the work progresses. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-SS Table 4.2.1 Runoff Conveyance and Treatment BMPs by SWPPP Element _ v _ O v U U N O U ++ ro O +p+ +p+ � *' Q p0 in iJ O O co O E' U C 00 a a N -p U O M C M v U % n ao � M -4 .� 3 v BMP or Element Name u OJ u �, U a, U p G +� in on C � C 41 C C C C N in C � C � C +' p' (U G1 E (U (U p a) C (U ++ N O '� y N O N W L.L ai w Ln w Ln W W U O W a_ W U > W d 0 BMP C200:Interceptor Dike and Swale ✓ ✓ BMP C201:Grass-Lined Channels ✓ ✓ BMP C202:Channel Lining ✓ BMP C203:Water Bars ✓ ✓ ✓ BMP C204:Pipe Slope Drains ✓ BMP C205:Subsurface Drains ✓ BMP C206:Level Spreader ✓ ✓ BMP C207:Check Dams ✓ ✓ ✓ ✓ BMP C208:Triangular Silt Dike(TSD) ✓ ✓ (Geotextile Encased Check Dam) BMP C209:Outlet Protection ✓ ✓ BMP C220:Storm Drain Inlet ✓ Protection BMP C231:Brush Barrier ✓ ✓ BMP C232:Gravel Filter Berm ✓ BMP C233:Silt Fence ✓ ✓ BMP C234:Vegetated Strip ✓ ✓ BMP C235:Wattles ✓ ✓ BMP C236:Vegetated Filtration ✓ BMP C240:Sediment Trap ✓ ✓ BMP C241:Temporary Sediment Pond ✓ ✓ Volume II— Construction Stormwater Pollution Prevention -December 2014 4-56 BMP C250:Construction Stormwater Chemical Treatment BMP C251:Construction Stormwater ✓ Filtration BMP C252:High pH Neutralization Using CO2 BMP C253:pH Control for High pH ✓ Water BMP C200: Interceptor Dike and Swale Purpose Provide a ridge of compacted soil, or a ridge with an upslope swale, at the top or base of a disturbed slope or along the perimeter of a disturbed construction area to convey stormwater. Use the dike and/or swale to intercept the runoff from unprotected areas and direct it to areas where erosion can be controlled. This can prevent storm runoff from entering the work area or sediment-laden runoff from leaving the construction site. Conditions of Use Where the runoff from an exposed site or disturbed slope must be conveyed to an erosion control facility which can safely convey the stormwater. • Locate upslope of a construction site to prevent runoff from entering disturbed area. • When placed horizontally across a disturbed slope, it reduces the amount and velocity of runoff flowing down the slope. • Locate downslope to collect runoff from a disturbed area and direct water to a sediment basin. Design and • Dike and/or swale and channel must be stabilized with temporary or Installation permanent vegetation or other channel protection during construction. Specifications • Channel requires a positive grade for drainage; steeper grades require channel protection and check dams. • Review construction for areas where overtopping may occur. • Can be used at top of new fill before vegetation is established. • May be used as a permanent diversion channel to carry the runoff. • Sub-basin tributary area should be one acre or less. • Design capacity for the peak volumetric flow rate calculated using a 10-minute time step from a 10-year, 24-hour storm, assuming a Type IA rainfall distribution, for temporary facilities. Alternatively,use 1.6 times the 10-year, 1-hour flow indicated by an approved continuous runoff model. For facilities that will also serve on a permanent basis, consult the local government's drainage requirements. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-57 Interceptor dikes shall meet the following criteria: Top Width 2 feet minimum. Height 1.5 feet minimum on berm. Side Slope 2H:1 V or flatter. Grade Depends on topography, however, dike system minimum is 0.5%, and maximum is 1%. Compaction Minimum of 90 percent ASTM D698 standard proctor. Horizontal Spacing of Interceptor Dikes: Average Slope Slope Percent Flowpath Length 20H:1V or less 3-5% 300 feet (10 to 20)H:1V 5-10% 200 feet (4 to 10)H:1V 10-25% 100 feet (2 to 4)H:1 V 25-50% 50 feet Stabilization depends on velocity and reach Slopes<5% Seed and mulch applied within 5 days of dike construction(see BMP C 121, Mulching). Slopes 5 - 40% Dependent on runoff velocities and dike materials. Stabilization should be done immediately using either sod or riprap or other measures to avoid erosion. • The upslope side of the dike shall provide positive drainage to the dike outlet. No erosion shall occur at the outlet. Provide energy dissipation measures as necessary. Sediment-laden runoff must be released through a sediment trapping facility. • Minimize construction traffic over temporary dikes. Use temporary cross culverts for channel crossing. Interceptor swales shall meet the following criteria: Bottom Width 2 feet minimum; the cross-section bottom shall be level. Depth 1-foot minimum. Side Slope 2H:1V or flatter. Grade Maximum 5 percent, with positive drainage to a suitable outlet(such as a sediment pond). Stabilization Seed as per BMP C 120, Temporary and Permanent Seeding, or BMP C202, Channel Lining, 12 inches thick riprap pressed into the bank and extending at least 8 inches vertical from the bottom. • Inspect diversion dikes and interceptor swales once a week and after every rainfall. Immediately remove sediment from the flow area. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-58 • Damage caused by construction traffic or other activity must be repaired before the end of each working day. Check outlets and make timely repairs as needed to avoid gully formation. When the area below the temporary diversion dike is permanently stabilized, remove the dike and fill and stabilize the channel to blend with the natural surface. BMP C201: Grass-Lined Channels Purpose To provide a channel with a vegetative lining for conveyance of runoff. See Figure 4.2.1 for typical grass-lined channels. Conditions of Use This practice applies to construction sites where concentrated runoff needs to be contained to prevent erosion or flooding. • When a vegetative lining can provide sufficient stability for the channel cross section and at lower velocities of water(normally dependent on grade). This means that the channel slopes are generally less than 5 percent and space is available for a relatively large cross section. • Typical uses include roadside ditches, channels at property boundaries, outlets for diversions, and other channels and drainage ditches in low areas. • Channels that will be vegetated should be installed before major earthwork and hydroseeded with a bonded fiber matrix (BFM). The vegetation should be well established(i.e., 75 percent cover)before water is allowed to flow in the ditch. With channels that will have high flows, erosion control blankets should be installed over the hydroseed. If vegetation cannot be established from seed before water is allowed in the ditch, sod should be installed in the bottom of the ditch in lieu of hydromulch and blankets. Design and Locate the channel where it can conform to the topography and other Installation features such as roads. Specifications . Locate them to use natural drainage systems to the greatest extent possible. • Avoid sharp changes in alignment or bends and changes in grade. • Do not reshape the landscape to fit the drainage channel. • The maximum design velocity shall be based on soil conditions, type of vegetation, and method of revegetation, but at no times shall velocity exceed 5 feet/second. The channel shall not be overtopped by the peak volumetric flow rate calculated using a 10-minute time step from a 10-year, 24-hour storm, assuming a Type I rainfall distribution. Alternatively, use 1.6 times the 10-year, 1-hour flow indicated by an approved continuous runoff model to determine a flow rate which the channel must contain. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-59 • Where the grass-lined channel will also function as a permanent stormwater conveyance facility, consult the drainage conveyance requirements of the local government with jurisdiction. • An established grass or vegetated lining is required before the channel can be used to convey stormwater, unless stabilized with nets or blankets. • If design velocity of a channel to be vegetated by seeding exceeds 2 ft/sec, a temporary channel liner is required. Geotextile or special mulch protection such as fiberglass roving or straw and netting provides stability until the vegetation is fully established. See Figure 4.2.2. • Check dams shall be removed when the grass has matured sufficiently to protect the ditch or swale unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. • If vegetation is established by sodding, the permissible velocity for established vegetation may be used and no temporary liner is needed. • Do not subject grass-lined channel to sedimentation from disturbed areas. Use sediment-trapping BMPs upstream of the channel. • V-shaped grass channels generally apply where the quantity of water is small, such as in short reaches along roadsides. The V-shaped cross section is least desirable because it is difficult to stabilize the bottom where velocities may be high. • Trapezoidal grass channels are used where runoff volumes are large and slope is low so that velocities are nonerosive to vegetated linings. (Note: it is difficult to construct small parabolic shaped channels.) • Subsurface drainage, or riprap channel bottoms, may be necessary on sites that are subject to prolonged wet conditions due to long duration flows or a high water table. • Provide outlet protection at culvert ends and at channel intersections. • Grass channels, at a minimum, should carry peak runoff for temporary construction drainage facilities from the 10-year, 24-hour storm without eroding. Where flood hazard exists, increase the capacity according to the potential damage. • Grassed channel side slopes generally are constructed 3H:1 V or flatter to aid in the establishment of vegetation and for maintenance. • Construct channels a minimum of 0.2 foot larger around the periphery to allow for soil bulking during seedbed preparations and sod buildup. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-60 Maintenance During the establishment period, check grass-lined channels after every Standards rainfall. • After grass is established, periodically check the channel; check it after every heavy rainfall event. Immediately make repairs. • It is particularly important to check the channel outlet and all road crossings for bank stability and evidence of piping or scour holes. • Remove all significant sediment accumulations to maintain the designed carrying capacity. Keep the grass in a healthy, vigorous condition at all times, since it is the primary erosion protection for the channel. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-61 Typical V-Shaped Channel Cross-section Filter (150-225mmi Fabric i��/�\ Key in Fabric Grass-Lined With Rock Center Typical Parabolic Channel Cross-Section �� Ili a Ali 6"-9" 050-225mm) /\\ j\ Filter /. Key In Fabric Fabric I with Channel Liner With Rock Center for Base Flow Typical Trapezoidal Channel Cross-Section Design Depth \ \\I Dvercut channel bulking during /�\\ \\;�\\j�\j: \�\\\��\\// to seedbed preparation and growth of vegetation. Filter \ With Rock Center For Base Flow Fabric Figure 4.2.1 —Typical Grass-Lined Channels Volume H Construction Stormwater Pollution Prevention -December 2014 4-62 `1 Overlap 6'(150mm)minimum Excavate Channel to Design �. Grade and Cross Section \ � �9 (n DeP OVERCUTCHANNEL Longitudinal 2'(50mm) TOALLOW anchor trench BULKING DURING SEEDBED PREPARATION rr ► TYPICAL INSTALLATION \ \ \ WITHEROSIONCONTROL BLANKETS OR TURF REINFORCEMENTMATS \/\\/\\/ \/\\/\\ Intermittent Check Slot Longitudinal Anchor Trench Shingle-lap spliced ends or begin new roll in an intermittent check slot Prepare soil and apply seed before installing blankets,mats or other N temporary channel liner system NOTES: 1 Design velocities exceeding 2 ft/sec (0.5m/sec)require temporary blankets, mats or similar liners to protect seed and soil until vegetation becomes established. 2 Grass-lined channels with design velocities exceeding 6 ft/sec (2m/sec) should include turf reinforcement mats. Figure 4.2.2—Temporary Channel Liners Volume II— Construction Stormwater Pollution Prevention -December 2014 4-63 BMP C202: Channel Lining Purpose To protect channels by providing a channel liner using either blankets or riprap. Conditions of When natural soils or vegetated stabilized soils in a channel are not adequate Use to prevent channel erosion. • When a permanent ditch or pipe system is to be installed and a temporary measure is needed. • In almost all cases, synthetic and organic coconut blankets are more effective than riprap for protecting channels from erosion. Blankets can be used with and without vegetation. Blanketed channels can be designed to handle any expected flow and longevity requirement. Some synthetic blankets have a predicted life span of 50 years or more, even in sunlight. • Other reasons why blankets are better than rock include the availability of blankets over rock. In many areas of the state, rock is not easily obtainable or is very expensive to haul to a site. Blankets can be delivered anywhere. Rock requires the use of dump trucks to haul and heavy equipment to place. Blankets usually only require laborers with hand tools, and sometimes a backhoe. • The Federal Highway Administration recommends not using flexible liners whenever the slope exceeds 10 percent or the shear stress exceeds 8 lbs/fe. Design and See BMP C 122 for information on blankets. Installation Since riprap is used where erosion potential is high, construction must be Specifications sequenced so that the riprap is put in place with the minimum possible delay. • Disturbance of areas where riprap is to be placed should be undertaken only when final preparation and placement of the riprap can follow immediately behind the initial disturbance. Where riprap is used for outlet protection, the riprap should be placed before or in conjunction with the construction of the pipe or channel so that it is in place when the pipe or channel begins to operate. • The designer, after determining the riprap size that will be stable under the flow conditions, shall consider that size to be a minimum size and then, based on riprap gradations actually available in the area, select the size or sizes that equal or exceed the minimum size. The possibility of drainage structure damage by children shall be considered in selecting a riprap size, especially if there is nearby water or a gully in which to toss the stones. • Stone for riprap shall consist of field stone or quarry stone of approximately rectangular shape. The stone shall be hard and angular Volume II—Construction Stormwater Pollution Prevention -December 2014 4-64 and of such quality that it will not disintegrate on exposure to water or weathering and it shall be suitable in all respects for the purpose intended. • A lining of engineering filter fabric (geotextile) shall be placed between the riprap and the underlying soil surface to prevent soil movement into or through the riprap. The geotextile should be keyed in at the top of the bank. • Filter fabric shall not be used on slopes greater than 1-1/2H:1V as slippage may occur. It should be used in conjunction with a layer of coarse aggregate (granular filter blanket)when the riprap to be placed is 12 inches and larger. BMP C203: Water Bars Purpose A small ditch or ridge of material is constructed diagonally across a road or right-of-way to divert stormwater runoff from the road surface, wheel tracks, or a shallow road ditch. See Figure 4.2.3. Conditions of use Clearing right-of-way and construction of access for power lines, pipelines, and other similar installations often require long narrow right-of-ways over sloping terrain. Disturbance and compaction promotes gully formation in these cleared strips by increasing the volume and velocity of runoff. Gully formation may be especially severe in tire tracks and ruts. To prevent gullying, runoff can often be diverted across the width of the right-of-way to undisturbed areas by using small predesigned diversions. • Give special consideration to each individual outlet area, as well as to the cumulative effect of added diversions. Use gravel to stabilize the diversion where significant vehicular traffic is anticipated. Design and Height: 8-inch minimum measured from the channel bottom to the ridge top. Installation Side slope of channel: 2H:1 V maximum; 3H:1 V or flatter when vehicles Specifications will cross. • Base width of ridge: 6-inch minimum. • Locate them to use natural drainage systems and to discharge into well vegetated stable areas. • Guideline for Spacing: Slope % Spacing (ft) < 5 125 5 - 10 100 10 -20 75 20 - 35 50 > 35 Use rock lined ditch Volume II—Construction Stormwater Pollution Prevention -December 2014 4-65 • Grade of water bar and angle: Select angle that results in ditch slope less than 2 percent. • Install as soon as the clearing and grading is complete. Reconstruct when construction is complete on a section when utilities are being installed. • Compact the ridge when installed. • Stabilize, seed, and mulch the portions that are not subject to traffic. Gravel the areas crossed by vehicles. Maintenance Periodically inspect right-of-way diversions for wear and after every heavy Standards rainfall for erosion damage. • Immediately remove sediment from the flow area and repair the dike. • Check outlet areas and make timely repairs as needed. • When permanent road drainage is established and the area above the temporary right-of-way diversion is permanently stabilized, remove the dikes and fill the channel to blend with the natural ground, and appropriately stabilize the disturbed area. ated l(l � io m dip to const ct . r; DE EP VIA TE R BA R �,B;;I � R A=24 to 30 inches ?' �/ �� O B-6 to 10 feet '• �� SHALLOW WATER BAR A=8 to 1 2 inches B=6to12feet Figure 4.2.3—Water Bar Volume II—Construction Stormwater Pollution Prevention -December 2014 4-66 BMP C204: Pipe Slope Drains Purpose To use a pipe to convey stormwater anytime water needs to be diverted away from or over bare soil to prevent gullies, channel erosion, and saturation of slide-prone soils. Conditions of Use Pipe slope drains should be used when a temporary or permanent stormwater conveyance is needed to move the water down a steep slope to avoid erosion(Figure 4.2.4). On highway projects, pipe slope drains should be used at bridge ends to collect runoff and pipe it to the base of the fill slopes along bridge approaches. These can be designed into a project and included as bid items. Another use on road projects is to collect runoff from pavement and pipe it away from side slopes. These are useful because there is generally a time lag between having the first lift of asphalt installed and the curbs, gutters, and permanent drainage installed. Used in conjunction with sand bags, or other temporary diversion devices, these will prevent massive amounts of sediment from leaving a project. Water can be collected, channeled with sand bags, Triangular Silt Dikes, berms, or other material, and piped to temporary sediment ponds. Pipe slope drains can be: • Connected to new catch basins and used temporarily until all permanent piping is installed; • Used to drain water collected from aquifers exposed on cut slopes and take it to the base of the slope; • Used to collect clean runoff from plastic sheeting and direct it away from exposed soil; • Installed in conjunction with silt fence to drain collected water to a controlled area; • Used to divert small seasonal streams away from construction. They have been used successfully on culvert replacement and extension jobs. Large flex pipe can be used on larger streams during culvert removal, repair, or replacement; and, • Connected to existing down spouts and roof drains and used to divert water away from work areas during building renovation, demolition, and construction projects. There are now several commercially available collectors that are attached to the pipe inlet and help prevent erosion at the inlet. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-67 Design and Size the pipe to convey the flow. The capacity for temporary drains shall be Installation sufficient to handle the peak volumetric flow rate calculated using a 10- Specifications minute time step from a 10-year, 24-hour storm event, assuming a Type IA rainfall distribution. Alternatively, use 1.6 times the 10-year, 1-hour flow indicated by an approved continuous runoff model. Consult local drainage requirements for sizing permanent pipe slope drains. • Use care in clearing vegetated slopes for installation. • Re-establish cover immediately on areas disturbed by installation. • Use temporary drains on new cut or fill slopes. • Use diversion dikes or swales to collect water at the top of the slope. • Ensure that the entrance area is stable and large enough to direct flow into the pipe. • Piping of water through the berm at the entrance area is a common failure mode. • The entrance shall consist of a standard flared end section for culverts 12 inches and larger with a minimum 6-inch metal toe plate to prevent runoff from undercutting the pipe inlet. The slope of the entrance shall be at least 3 percent. Sand bags may also be used at pipe entrances as a temporary measure. • The soil around and under the pipe and entrance section shall be thoroughly compacted to prevent undercutting. • The flared inlet section shall be securely connected to the slope drain and have watertight connecting bands. • Slope drain sections shall be securely fastened together, fused or have gasketed watertight fittings, and shall be securely anchored into the soil. • Thrust blocks should be installed anytime 90 degree bends are utilized. Depending on size of pipe and flow, these can be constructed with sand bags, straw bales staked in place, "t"posts and wire, or ecology blocks. • Pipe needs to be secured along its full length to prevent movement. This can be done with steel "t"posts and wire. A post is installed on each side of the pipe and the pipe is wired to them. This should be done every 10-20 feet of pipe length or so, depending on the size of the pipe and quantity of water to divert. • Interceptor dikes shall be used to direct runoff into a slope drain. The height of the dike shall be at least 1 foot higher at all points than the top of the inlet pipe. • The area below the outlet must be stabilized with a riprap apron (see BMP C209 Outlet Protection, for the appropriate outlet material). Volume II—Construction Stormwater Pollution Prevention -December 2014 4-68 • If the pipe slope drain is conveying sediment-laden water, direct all flows into the sediment trapping facility. • Materials specifications for any permanent piped system shall be set by the local government. Maintenance Check inlet and outlet points regularly, especially after storms. Standards The inlet should be free of undercutting, and no water should be going around the point of entry. If there are problems, the headwall should be reinforced with compacted earth or sand bags. • The outlet point should be free of erosion and installed with appropriate outlet protection. • For permanent installations, inspect pipe periodically for vandalism and physical distress such as slides and wind-throw. • Normally the pipe slope is so steep that clogging is not a problem with smooth wall pipe, however, debris may become lodged in the pipe. Dike material compacted 90%modified proctor CPEP or equivalent pipe Interceptor Dike 12' WIN. \ — Provide riprap pad �L —_� or equivalent energy dissipation Discharge to a stabilized Standard flared watercourse,sediment retention end section facility,or stabilized outlet Inlet and all sections must be securely fastened together with gasketed watertight fittings Figure 4.2.4— Pipe Slope Drain Volume II—Construction Stormwater Pollution Prevention -December 2014 4-69 BMP C205: Subsurface Drains Purpose To intercept, collect, and convey ground water to a satisfactory outlet, using a perforated pipe or conduit below the ground surface. Subsurface drains are also known as "french drains."The perforated pipe provides a dewatering mechanism to drain excessively wet soils, provide a stable base for construction, improve stability of structures with shallow foundations, or to reduce hydrostatic pressure to improve slope stability. Conditions of Use Use when excessive water must be removed from the soil. The soil permeability, depth to water table and impervious layers are all factors which may govern the use of subsurface drains. Design and Relief drains are used either to lower the water table in large, relatively Installation flat areas, improve the growth of vegetation, or to remove surface water. Specifications Relief drains are installed along a slope and drain in the direction of the slope. They can be installed in a grid pattern, a herringbone pattern, or a random pattern. • Interceptor drains are used to remove excess ground water from a slope, stabilize steep slopes, and lower the water table immediately below a slope to prevent the soil from becoming saturated. Interceptor drains are installed perpendicular to a slope and drain to the side of the slope. They usually consist of a single pipe or series of single pipes instead of a patterned layout. • Depth and spacing of interceptor drains --The depth of an interceptor drain is determined primarily by the depth to which the water table is to be lowered or the depth to a confining layer. For practical reasons, the maximum depth is usually limited to 6 feet, with a minimum cover of 2 feet to protect the conduit. • The soil should have depth and sufficient permeability to permit installation of an effective drainage system at a depth of 2 to 6 feet. • An adequate outlet for the drainage system must be available either by gravity or by pumping. • The quantity and quality of discharge needs to be accounted for in the receiving stream(additional detention may be required). • This standard does not apply to subsurface drains for building foundations or deep excavations. • The capacity of an interceptor drain is determined by calculating the maximum rate of ground water flow to be intercepted. Therefore, it is Volume II—Construction Stormwater Pollution Prevention -December 2014 4-70 good practice to make complete subsurface investigations, including hydraulic conductivity of the soil,before designing a subsurface drainage system. • Size of drain--Size subsurface drains to carry the required capacity without pressure flow. Minimum diameter for a subsurface drain is 4 inches. • The minimum velocity required to prevent silting is 1.4 ft./sec. The line shall be graded to achieve this velocity at a minimum. The maximum allowable velocity using a sand-gravel filter or envelope is 9 ft/sec. • Filter material and fabric shall be used around all drains for proper bedding and filtration of fine materials. Envelopes and filters should surround the drain to a minimum of 3-inch thickness. • The outlet of the subsurface drain shall empty into a sediment pond through a catch basin. If free of sediment, it can then empty into a receiving channel, swale, or stable vegetated area adequately protected from erosion and undermining. • The trench shall be constructed on a continuous grade with no reverse grades or low spots. • Soft or yielding soils under the drain shall be stabilized with gravel or other suitable material. • Backfilling shall be done immediately after placement of the pipe. No sections of pipe shall remain uncovered overnight or during a rainstorm. Backfill material shall be placed in the trench in such a manner that the drain pipe is not displaced or damaged. • Do not install permanent drains near trees to avoid the tree roots that tend to clog the line. Use solid pipe with watertight connections where it is necessary to pass a subsurface drainage system through a stand of trees. • Outlet--Ensure that the outlet of a drain empties into a channel or other watercourse above the normal water level. • Secure an animal guard to the outlet end of the pipe to keep out rodents. • Use outlet pipe of corrugated metal, cast iron, or heavy-duty plastic without perforations and at least 10 feet long. Do not use an envelope or filter material around the outlet pipe, and bury at least two-thirds of the pipe length. • When outlet velocities exceed those allowable for the receiving stream, outlet protection must be provided. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-71 Maintenance Subsurface drains shall be checked periodically to ensure that they are Standards free-flowing and not clogged with sediment or roots. • The outlet shall be kept clean and free of debris. • Surface inlets shall be kept open and free of sediment and other debris. • Trees located too close to a subsurface drain often clog the system with their roots. If a drain becomes clogged, relocate the drain or remove the trees as a last resort. Drain placement should be planned to minimize this problem. • Where drains are crossed by heavy vehicles, the line shall be checked to ensure that it is not crushed. BMP C206: Level Spreader Purpose To provide a temporary outlet for dikes and diversions consisting of an excavated depression constructed at zero grade across a slope. To convert concentrated runoff to sheet flow and release it onto areas stabilized by existing vegetation or an engineered filter strip. Conditions of Use Used when a concentrated flow of water needs to be dispersed over a large area with existing stable vegetation. • Items to consider are: 1. What is the risk of erosion or damage if the flow may become concentrated? 2. Is an easement required if discharged to adjoining property? 3. Most of the flow should be as ground water and not as surface flow. 4. Is there an unstable area downstream that cannot accept additional ground water? • Use only where the slopes are gentle, the water volume is relatively low, and the soil will adsorb most of the low flow events. Design and Use above undisturbed areas that are stabilized by existing vegetation. Installation If the level spreader has any low points, flow will concentrate, create Specifications channels and may cause erosion. • Discharge area below the outlet must be uniform with a slope flatter than 5H:IV. • Outlet to be constructed level in a stable, undisturbed soil profile (not on fill). • The runoff shall not re-concentrate after release unless intercepted by another downstream measure. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-72 • The grade of the channel for the last 20 feet of the dike or interceptor entering the level spreader shall be less than or equal to 1 percent. The grade of the level spreader shall be 0 percent to ensure uniform spreading of storm runoff. • A 6-inch high gravel berm placed across the level lip shall consist of washed crushed rock, 2-to 4-inch or 3/4-inch to 11/2-inch size. • The spreader length shall be determined by estimating the peak flow expected from the 10-year, 24-hour design storm. The length of the spreader shall be a minimum of 15 feet for 0.1 cfs and shall increase by 10 feet for each 0.1 cfs thereafter to a maximum of 0.5 cfs per spreader. Use multiple spreaders for higher flows. • The width of the spreader should be at least 6 feet. • The depth of the spreader as measured from the lip should be at least 6 inches and it should be uniform across the entire length. • Level spreaders shall be setback from the property line unless there is an easement for flow. • Level spreaders, when installed every so often in grassy swales, keep the flows from concentrating. Materials that can be used include sand bags, lumber, logs, concrete, and pipe. To function properly, the material needs to be installed level and on contour. F 4.2.5Fi. rug e425 and 4.2.6 provide a cross-section and a detail of a level spreader. A capped perforated pipe could also be used as a spreader. Maintenance The spreader should be inspected after every runoff event to ensure that it Standards is functioning correctly. • The contractor should avoid the placement of any material on the structure and should prevent construction traffic from crossing over the structure. • If the spreader is damaged by construction traffic, it shall be immediately repaired. Pressure-Treated 2"x10" Densely vegetated for a Min. of 100' and slope tea+—�— less than 5:1 �N 1'Min. III=I -''� 3' Min. Figure 4.2.5—Cross Section of Level Spreader Volume II—Construction Stormwater Pollution Prevention -December 2014 4-73 Treated 2"x10" may be abutted end to Spreader must be level end for max. spreader length of 50' 6" min. 1" min. 6" min. II=III=III=1 I—III—III—III—III+F1=III—III=III=III=11 III=III=III 18" min. rebar supports 8' max. spacing Figure 4.2.6— Detail of Level Spreader BMP C207: Check Dams Purpose Construction of small dams across a swale or ditch reduces the velocity of concentrated flow and dissipates energy at the check dam. Conditions of Use Where temporary channels or permanent channels are not yet vegetated, channel lining is infeasible, and/or velocity checks are required. • Check dams may not be placed in streams unless approved by the State Department of Fish and Wildlife. Check dams may not be placed in wetlands without approval from a permitting agency. • Do not place check dams below the expected backwater from any salmonid bearing water between October 1 and May 31 to ensure that there is no loss of high flow refuge habitat for overwintering juvenile salmonids and emergent salmonid fry. • Construct rock check dams from appropriately sized rock. The rock used must be large enough to stay in place given the expected design flow through the channel. The rock must be placed by hand or by mechanical means (no dumping of rock to form dam)to achieve complete coverage of the ditch or swale and to ensure that the center of the dam is lower than the edges. • Check dams may also be constructed of either rock or pea-gravel filled bags. Numerous new products are also available for this purpose. They tend to be re-usable, quick and easy to install, effective, and cost efficient. • Place check dams perpendicular to the flow of water. • The dam should form a triangle when viewed from the side. This prevents undercutting as water flows over the face of the dam rather than falling directly onto the ditch bottom. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-74 • Before installing check dams impound and bypass upstream water flow away from the work area. Options for bypassing include pumps, siphons, or temporary channels. • Check dams in association with sumps work more effectively at slowing flow and retaining sediment than just a check dam alone. A deep sump should be provided immediately upstream of the check dam. • In some cases, if carefully located and designed, check dams can remain as permanent installations with very minor regrading. They may be left as either spillways, in which case accumulated sediment would be graded and seeded, or as check dams to prevent further sediment from leaving the site. • The maximum spacing between the dams shall be such that the toe of the upstream dam is at the same elevation as the top of the downstream dam. • Keep the maximum height at 2 feet at the center of the dam. • Keep the center of the check dam at least 12 inches lower than the outer edges at natural ground elevation. • Keep the side slopes of the check dam at 211:1 V or flatter. • Key the stone into the ditch banks and extend it beyond the abutments a minimum of 18 inches to avoid washouts from overflow around the dam. • Use filter fabric foundation under a rock or sand bag check dam. If a blanket ditch liner is used, filter fabric is not necessary. A piece of organic or synthetic blanket cut to fit will also work for this purpose. • In the case of grass-lined ditches and swales, all check dams and accumulated sediment shall be removed when the grass has matured sufficiently to protect the ditch or swale -unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. • Ensure that channel appurtenances, such as culvert entrances below check dams, are not subject to damage or blockage from displaced stones. Figure 4.2.7 depicts a typical rock check dam. Maintenance Check dams shall be monitored for performance and sediment Standards accumulation during and after each runoff producing rainfall. Sediment shall be removed when it reaches one half the sump depth. • Anticipate submergence and deposition above the check dam and erosion from high flows around the edges of the dam. • If significant erosion occurs between dams, install a protective riprap liner in that portion of the channel. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-75 Approved as Ecology has approved products as able to meet the requirements of BMP Equivalent C207. The products did not pass through the Technology Assessment Protocol—Ecology(TAPE)process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at hM2://www.ecy.wa.gov/pro,grams/wq/stormwater/newtech/equivalent.html Volume II—Construction Stormwater Pollution Prevention -December 2014 4-76 View Looking Upstream A 18"(0.5m) 12" (150mm) s° °° ° ° oo * o�o ��go °�i 24"(0.6m) NOTE: °off° °oo o��o °° i o° Key stone into channel banks and extend it beyond the abutments a minimum of 18"(0.5m)to prevent A flow around dam. Section A - A FLOW 24" (0.6m) �0000 °e °�ao00000 on �e Oo o 8' (2.4m) Spacing Between Check Dams 'L'=the distance such that points'A'and 'B'are of equal elevation. 'L' o 0o vo. Oo�oaf ��POINT'A' �POINT'B' \ \\\X NOT TO SCALE Figure 4.2.7— Rock Check Dam Volume II— Construction Stormwater Pollution Prevention -December 2014 4-77 BMP C208: Triangular Silt Dike (TSD) (Geotextile-Encased Check Dam) Purpose Triangular silt dikes may be used as check dams, for perimeter protection, for temporary soil stockpile protection, for drop inlet protection, or as a temporary interceptor dike. Conditions of use • May be used on soil or pavement with adhesive or staples. • TSDs have been used to build temporary: 1. sediment ponds; 2. diversion ditches; 3. concrete wash out facilities; 4. curbing; 5. water bars; 6. level spreaders; and, 7. berms. Design and Made of urethane foam sewn into a woven geosynthetic fabric. Installation It is triangular, 10 inches to 14 inches high in the center, with a 20-inch to Specifications 28-inch base. A 2—foot apron extends beyond both sides of the triangle along its standard section of 7 feet. A sleeve at one end allows attachment of additional sections as needed. • Install with ends curved up to prevent water from flowing around the ends. • The fabric flaps and check dam units are attached to the ground with wire staples. Wire staples should be No. 1 I gauge wire and should be 200 mm to 300 mm in length. • When multiple units are installed, the sleeve of fabric at the end of the unit shall overlap the abutting unit and be stapled. • Check dams should be located and installed as soon as construction will allow. • Check dams should be placed perpendicular to the flow of water. • When used as check dams, the leading edge must be secured with rocks, sandbags, or a small key slot and staples. • In the case of grass-lined ditches and swales, check dams and accumulated sediment shall be removed when the grass has matured sufficiently to protect the ditch or swale unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. Maintenance • Triangular silt dams shall be inspected for performance and sediment Volume II—Construction Stormwater Pollution Prevention-December 2014 4-78 Standards accumulation during and after each runoff producing rainfall. Sediment shall be removed when it reaches one half the height of the dam. • Anticipate submergence and deposition above the triangular silt dam and erosion from high flows around the edges of the dam. Immediately repair any damage or any undercutting of the dam. BMP C209: Outlet Protection Purpose Outlet protection prevents scour at conveyance outlets and minimizes the potential for downstream erosion by reducing the velocity of concentrated stormwater flows. Conditions of use Outlet protection is required at the outlets of all ponds,pipes, ditches, or other conveyances, and where runoff is conveyed to a natural or manmade drainage feature such as a stream, wetland, lake, or ditch. Design and The receiving channel at the outlet of a culvert shall be protected from Installation erosion by rock lining a minimum of 6 feet downstream and extending up Specifications the channel sides a minimum of 1—foot above the maximum tailwater elevation or 1-foot above the crown, whichever is higher. For large pipes (more than 18 inches in diameter), the outlet protection lining of the channel is lengthened to four times the diameter of the culvert. • Standard wingwalls, and tapered outlets and paved channels should also be considered when appropriate for permanent culvert outlet protection. (See WSDOT Hydraulic Manual, available through WSDOT Engineering Publications). • Organic or synthetic erosion blankets, with or without vegetation, are usually more effective than rock, cheaper, and easier to install. Materials can be chosen using manufacturer product specifications. ASTM test results are available for most products and the designer can choose the correct material for the expected flow. • With low flows, vegetation(including sod) can be effective. • The following guidelines shall be used for riprap outlet protection: 1. If the discharge velocity at the outlet is less than 5 fps (pipe slope less than 1 percent),use 2-inch to 8-inch riprap. Minimum thickness is 1-foot. 2. For 5 to 10 fps discharge velocity at the outlet(pipe slope less than 3 percent),use 24-inch to 48-inch riprap. Minimum thickness is 2 feet. 3. For outlets at the base of steep slope pipes (pipe slope greater than 10 percent), an engineered energy dissipater shall be used. • Filter fabric or erosion control blankets should always be used under riprap to prevent scour and channel erosion. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-79 New pipe outfalls can provide an opportunity for low-cost fish habitat improvements. For example, an alcove of low-velocity water can be created by constructing the pipe outfall and associated energy dissipater back from the stream edge and digging a channel, over- widened to the upstream side, from the outfall. Overwintering juvenile and migrating adult salmonids may use the alcove as shelter during high flows. Bank stabilization, bioengineering, and habitat features may be required for disturbed areas. This work may require a HPA. See Volume V for more information on outfall system design. Maintenance • Inspect and repair as needed. Standards . Add rock as needed to maintain the intended function. • Clean energy dissipater if sediment builds up. BMP C220: Storm Drain Inlet Protection Purpose Storm drain inlet protection prevents coarse sediment from entering drainage systems prior to permanent stabilization of the disturbed area. Conditions of Use Use storm drain inlet protection at inlets that are operational before permanent stabilization of the disturbed drainage area. Provide protection for all storm drain inlets downslope and within 500 feet of a disturbed or construction area, unless conveying runoff entering catch basins to a sediment pond or trap. Also consider inlet protection for lawn and yard drains on new home construction. These small and numerous drains coupled with lack of gutters in new home construction can add significant amounts of sediment into the roof drain system. If possible delay installing lawn and yard drains until just before landscaping or cap these drains to prevent sediment from entering the system until completion of landscaping. Provide 18-inches of sod around each finished lawn and yard drain. Table 4.2.2 lists several options for inlet protection. All of the methods for storm drain inlet protection tend to plug and require a high frequency of maintenance. Limit drainage areas to one acre or less. Possibly provide emergency overflows with additional end-of-pipe treatment where stormwater ponding would cause a hazard. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-80 Table 4.2.2 Storm Drain Inlet Protection Applicable for Type of Inlet Emergency Paved/ Earthen Protection Overflow Surfaces Conditions of Use Drop Inlet Protection Excavated drop inlet Yes, Earthen Applicable for heavy flows. Easy protection temporary to maintain. Large area flooding will Requirement: 30' X 30'/acre occur Block and gravel drop Yes Paved or Earthen Applicablefor heavy concentrated inlet protection flows. Will not pond. Gravel and wire drop No Applicablefor heavy concentrated inlet protection flows. Will pond. Can withstand traffic. Catch basin filters Yes Paved or Earthen Frequent maintenance required. Curb Inlet Protection Curb inlet protection Small capacity Paved Used for sturdy, more compact with a wooden weir overflow installation. Block and gravel curb Yes Paved Sturdy, but limited filtration. inlet protection Culvert Inlet Protection Culvert inlet sediment 18 month expected life. trap Design and Excavated Drop Inlet Protection - An excavated impoundment around the Installation storm drain. Sediment settles out of the stormwater prior to entering the Specifications storm drain. • Provide a depth of 1-2 ft as measured from the crest of the inlet structure. • Slope sides of excavation no steeper than 2H:IV. • Minimum volume of excavation 35 cubic yards. • Shape basin to fit site with longest dimension oriented toward the longest inflow area. • Install provisions for draining to prevent standing water problems. • Clear the area of all debris. • Grade the approach to the inlet uniformly. • Drill weep holes into the side of the inlet. • Protect weep holes with screen wire and washed aggregate. • Seal weep holes when removing structure and stabilizing area. Volume II— Construction Stormwater Pollution Prevention -December 2014 4-81 • Build a temporary dike, if necessary, to the down slope side of the structure to prevent bypass flow. Block and Gravel Filter-A barrier formed around the storm drain inlet with standard concrete blocks and gravel. See Figure 4.2.8. • Provide a height of 1 to 2 feet above inlet. • Recess the first row 2-inches into the ground for stability. • Support subsequent courses by placing a 2x4 through the block opening. • Do not use mortar. • Lay some blocks in the bottom row on their side for dewatering the pool. • Place hardware cloth or comparable wire mesh with 1/2-inch openings over all block openings. • Place gravel just below the top of blocks on slopes of 2H:1 V or flatter. • An alternative design is a gravel donut. • Provide an inlet slope of 3H:1V. • Provide an outlet slope of 2H:IV. • Provide al-foot wide level stone area between the structure and the inlet. • Use inlet slope stones 3 inches in diameter or larger. • Use gravel '/2-to 3/4-inch at a minimum thickness of 1-foot for the outlet slope. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-82 Plan View A Drain O o Grate o �Qo ao ao0 0 ° 4� 6-0° 0 0 ado° oao0�0 v oo°DOo e DO' O oo Ooc, 0 � a�OooQ�Q ao0�41 00 o asOq�°,00 0o Concrete �0 ��oa oo Block g�4 ooeQe a 0` oLl ��oe�o O4 aOD°�O�o°o Gravel .O Backfill o 0 �DES 9 �00 00 ��°m00 0°oD o ��°oD °o"D o" °o"D �O 0 00 0 �ao04 Oo^ oo °aoOa�^/oo oa"O Oa�Oa oD°O � aD� DOS 0 �oo oa � �� Oo � O oDO Section A - A Concrete Block Wire Screen or Filter Fabric Gravel Backfill Overflow Water Ponding Height ° o o l a O 6O o� o Water) °�0� 000 Drop Inlet Notes: 1. Drop inlet sediment barriers are to be used for small,nearly level drainage areas.(less than 5%) 2. Excavate a basin of sufficient size adjacent to the drop inlet. 3.The top of the structure(ponding height)must be well below the ground elevation downslope to prevent runoff from bypassing the inlet.A temporary dike may be necessary on the downslope side of the structure. Figure 4.2.8- Block and Gravel Filter Gravel and Wire Mesh Filter- A gravel barrier placed over the top of the inlet. This structure does not provide an overflow. • Use a hardware cloth or comparable wire mesh with '/2-inch openings. • Use coarse aggregate. • Provide a height 1-foot or more, 18-inches wider than inlet on all sides. • Place wire mesh over the drop inlet so that the wire extends a minimum of 1-foot beyond each side of the inlet structure. • Overlap the strips if more than one strip of mesh is necessary. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-83 • Place coarse aggregate over the wire mesh. • Provide at least a 12-inch depth of gravel over the entire inlet opening and extend at least 18-inches on all sides. Catchbasin Filters—Use inserts designed by manufacturers for construction sites. The limited sediment storage capacity increases the amount of inspection and maintenance required, which may be daily for heavy sediment loads. To reduce maintenance requirements combine a catchbasin filter with another type of inlet protection. This type of inlet protection provides flow bypass without overflow and therefore may be a better method for inlets located along active rights-of-way. • Provides 5 cubic feet of storage. • Requires dewatering provisions. • Provides a high-flow bypass that will not clog under normal use at a construction site. • Insert the catchbasin filter in the catchbasin just below the grating. Curb Inlet Protection with Wooden Weir—Barrier formed around a curb inlet with a wooden frame and gravel. • Use wire mesh with 1/2-inch openings. • Use extra strength filter cloth. • Construct a frame. • Attach the wire and filter fabric to the frame. • Pile coarse washed aggregate against wire/fabric. • Place weight on frame anchors. Block and Gravel Curb Inlet Protection—Barrier formed around a curb inlet with concrete blocks and gravel. See Figure 4.2.9. • Use wire mesh with 1/2-inch openings. • Place two concrete blocks on their sides abutting the curb at either side of the inlet opening. These are spacer blocks. • Place a 2x4 stud through the outer holes of each spacer block to align the front blocks. • Place blocks on their sides across the front of the inlet and abutting the spacer blocks. • Place wire mesh over the outside vertical face. • Pile coarse aggregate against the wire to the top of the barrier. Curb and Gutter Sediment Barrier—Sandbag or rock berm(riprap and aggregate) 3 feet high and 3 feet wide in a horseshoe shape. See Figure 4.2.10. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-84 • Construct a horseshoe shaped berm, faced with coarse aggregate if using riprap, 3 feet high and 3 feet wide, at least 2 feet from the inlet. • Construct a horseshoe shaped sedimentation trap on the outside of the berm sized to sediment trap standards for protecting a culvert inlet. Maintenance • Inspect catch basin filters frequently, especially after storm events. Standards Clean and replace clogged inserts. For systems with clogged stone filters: pull away the stones from the inlet and clean or replace. An alternative approach would be to use the clogged stone as fill and put fresh stone around the inlet. • Do not wash sediment into storm drains while cleaning. Spread all excavated material evenly over the surrounding land area or stockpile and stabilize as appropriate. Approved as Ecology has approved products as able to meet the requirements of BMP Equivalent C220. The products did not pass through the Technology Assessment Protocol—Ecology(TAPE)process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at http://www.ecy.wa. og v/pro,grams/wq/stormwater/newtech/equivalent.html Volume II—Construction Stormwater Pollution Prevention -December 2014 4-85 Plan View Back of Sidewalk A Catch Basin 2x4 Wood Stud Back of Curb Concrete Block Curb Inlet `o� o Oo- ° a o�'°. °. oolY� oa °a °• Oo � bpdo o•.o� �0 p8O �.�mLH 000O°p. �Ua�b O°°• p °p• p°p° `O p• ° °op• g ° op�°• ` ao o oaO�g: o o oo �•o a g'o 4op.oQo�o°oop. 9° o Qo°�CQ °q°�o•Qo° op°o.oQ�.�°o °Oo•.D� o�. �o °° a�Q oaa ate•. 4 °o a a:° q o s oa.b�q •8�0° a Oo oa SJo 0 Wire Screen or Filter Fabric A Concrete Block Section A - A ( Drain Gravel 20mm) %"Drain Gravel (20mm) Ponding Height Concrete Block Overflow °g4 0 a Curb Inlet Wire Screen or Filter Fabric �\ Catch Basin \\' 4 Wood Stud (100x50 Timber Stud) \j NOTES: 1. Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment, where water can pond and allow sediment to separate from runoff. 2. Barrier shall allow for overflow from severe storm event. 3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately. Figure 4.2.9—Block and Gravel Curb Inlet Protection Volume II—Construction Stormwater Pollution Prevention -December 2014 4-86 Plan View Back of Sidewalk Burlap Sacks to Catch Basin Overlap onto Curb Curb Inlet Back of Curb RUNOFF RUNOFF SPILLWAY Gravel Filled Sandbags Stacked Tightly NOTES: 1.Place curb type sediment barriers on gently sloping street segments,where water can pond and allow sediment to separate from runoff. 2. Sandbags of either burlap or woven'geotextile'fabric,are filled with gravel,layered and packed tightly. 3.Leave a one sandbag gap in the top row to provide a spillway for overflow. 4.Inspect barriers and remove sediment after each storm event.Sediment and gravel must be removed from the traveled way immediately. Figure 4.2.10—Curb and Gutter Barrier Volume II— Construction Stormwater Pollution Prevention -December 2014 4-87 BMP C231: Brush Barrier Purpose The purpose of brush barriers is to reduce the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use • Brush barriers may be used downslope of all disturbed areas of less than one-quarter acre. Brush barriers are not intended to treat concentrated flows, nor are they intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to a sediment pond. The only circumstance in which overland flow can be treated solely by a brush barrier, rather than by a sediment pond, is when the area draining to the barrier is small. Brush barriers should only be installed on contours. Design and • Height 2 feet(minimum) to 5 feet(maximum). Installation . Width 5 feet at base (minimum) to 15 feet(maximum). Specifications • Filter fabric (geotextile) may be anchored over the brush berm to enhance the filtration ability of the barrier. Ten-ounce burlap is an adequate alternative to filter fabric. • Chipped site vegetation, composted mulch, or wood-based mulch (hog fuel) can be used to construct brush barriers. • A 100 percent biodegradable installation can be constructed using 10- ounce burlap held in place by wooden stakes. Figure 4.2.11 depicts a typical brush barrier. Maintenance • There shall be no signs of erosion or concentrated runoff under or Standards around the barrier. If concentrated flows are bypassing the barrier, it must be expanded or augmented by toed-in filter fabric. The dimensions of the barrier must be maintained. If required,drape filter fabric over brush and secure in 4"x4" min.trench with compacted backfill. Anchor downhill edge of - filter fabric with stakes, sandbags,or equivalent. �*C 2'Min.Height Min.5'wide brush barrier with max.6"diameter woody debris. Alternatively topsoil strippings may be used to form the barrier. Figure 4.2.11 —Brush Barrier Volume II—Construction Stormwater Pollution Prevention -December 2014 4-88 BMP C232: Gravel Filter Berm Purpose A gravel filter berm is constructed on rights-of-way or traffic areas within a construction site to retain sediment by using a filter berm of gravel or crushed rock. Conditions of Use Where a temporary measure is needed to retain sediment from rights-of- way or in traffic areas on construction sites. Design and Berm material shall be 3/4 to 3 inches in size, washed well-grade gravel Installation or crushed rock with less than 5 percent fines. Specifications Spacing of berms: — Every 300 feet on slopes less than 5 percent — Every 200 feet on slopes between 5 percent and 10 percent — Every 100 feet on slopes greater than 10 percent • Berm dimensions: — 1 foot high with 3H:1 V side slopes — 8 linear feet per 1 cfs runoff based on the I0-year, 24-hour design storm Maintenance • Regular inspection is required. Sediment shall be removed and filter Standards material replaced as needed. BMP C233: Silt Fence Purpose Use of a silt fence reduces the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. See Figure 4.2.12 for details on silt fence construction. Conditions of Use Silt fence may be used downslope of all disturbed areas. • Silt fence shall prevent soil carried by runoff water from going beneath, through, or over the top of the silt fence, but shall allow the water to pass through the fence. • Silt fence is not intended to treat concentrated flows, nor is it intended to treat substantial amounts of overland flow. Convey any concentrated flows through the drainage system to a sediment pond. • Do not construct silt fences in streams or use in V-shaped ditches. Silt fences do not provide an adequate method of silt control for anything deeper than sheet or overland flow. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-89 Joints in filter fabric shall be spliced at posts. Use staples,wire rings or 2"x2"by 14 Ga.wire or equivalent to attach fabric to posts equivalent, if standard r� strength fabric used I Filter fabric II E CV II 6'max Minimum 4"x4"trench - .E N J Backfill trench with native soil' I �� Post spacing may be increased or 3/4"-1.5"washed gravel to 8'if wire backing is used 2"x2"wood posts,steel fence posts,or equivalent Figure 4.2.12—Silt Fence Design and • Use in combination with sediment basins or other BMPs. Installation Maximum slope steepness (normal (perpendicular) to fence line) Specifications 1H:IV. Maximum sheet or overland flow path length to the fence of 100 feet. • Do not allow flows greater than 0.5 cfs. The geotextile used shall meet the following standards. All geotextile properties listed below are minimum average roll values (i.e., the test result for any sampled roll in a lot shall meet or exceed the values shown in Table 4.2.3): Table 4.2.3 Geotextile Standards Polymeric Mesh AOS 0.60 mm maximum for slit film woven(#30 sieve).0.30 (ASTM D4751) mm maximum for all other geotextile types(#50 sieve). 0.15 mm minimum for all fabric types(#100 sieve). Water Permittivity 0.02 sec minimum (ASTM D4491) Grab Tensile Strength 180 lbs.Minimum for extra strength fabric. (ASTM D4632) 100 lbs minimum for standard strength fabric. Grab Tensile Strength 30%maximum (ASTM D4632) Ultraviolet Resistance 70%minimum (ASTM D4355) • Support standard strength fabrics with wire mesh, chicken wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the strength of the fabric. Silt fence materials are available that have synthetic mesh backing attached. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-90 • Filter fabric material shall contain ultraviolet ray inhibitors and stabilizers to provide a minimum of six months of expected usable construction life at a temperature range of 0°F. to 120°F. • One-hundred percent biodegradable silt fence is available that is strong, long lasting, and can be left in place after the project is completed, if permitted by local regulations. • Refer to Figure 4.2.12 for standard silt fence details. Include the following standard Notes for silt fence on construction plans and specifications: 1. The contractor shall install and maintain temporary silt fences at the locations shown in the Plans. 2. Construct silt fences in areas of clearing, grading, or drainage prior to starting those activities. 3. The silt fence shall have a 2-feet min. and a 2'/2-feet max. height above the original ground surface. 4. The filter fabric shall be sewn together at the point of manufacture to form filter fabric lengths as required. Locate all sewn seams at support posts. Alternatively, two sections of silt fence can be overlapped, provided the Contractor can demonstrate, to the satisfaction of the Engineer, that the overlap is long enough and that the adjacent fence sections are close enough together to prevent silt laden water from escaping through the fence at the overlap. 5. Attach the filter fabric on the up-slope side of the posts and secure with staples, wire, or in accordance with the manufacturer's recommendations. Attach the filter fabric to the posts in a manner that reduces the potential for tearing. 6. Support the filter fabric with wire or plastic mesh, dependent on the properties of the geotextile selected for use. If wire or plastic mesh is used, fasten the mesh securely to the up-slope side of the posts with the filter fabric up-slope of the mesh. 7. Mesh support, if used, shall consist of steel wire with a maximum mesh spacing of 2-inches, or a prefabricated polymeric mesh. The strength of the wire or polymeric mesh shall be equivalent to or greater than 180 lbs. grab tensile strength. The polymeric mesh must be as resistant to the same level of ultraviolet radiation as the filter fabric it supports. 8. Bury the bottom of the filter fabric 4-inches min. below the ground surface. Backfill and tamp soil in place over the buried portion of the filter fabric, so that no flow can pass beneath the fence and scouring cannot occur. When wire or polymeric back-up support Volume II—Construction Stormwater Pollution Prevention -December 2014 4-91 mesh is used, the wire or polymeric mesh shall extend into the ground 3-inches min. 9. Drive or place the fence posts into the ground 18-inches min. A 12—inch min. depth is allowed if topsoil or other soft subgrade soil is not present and 18-inches cannot be reached. Increase fence post min. depths by 6 inches if the fence is located on slopes of 3H:1 V or steeper and the slope is perpendicular to the fence. If required post depths cannot be obtained, the posts shall be adequately secured by bracing or guying to prevent overturning of the fence due to sediment loading. 10. Use wood, steel or equivalent posts. The spacing of the support posts shall be a maximum of 6-feet. Posts shall consist of either: • Wood with dimensions of 2-inches by 2-inches wide min. and a 3-feet min. length. Wood posts shall be free of defects such as knots, splits, or gouges. • No. 6 steel rebar or larger. • ASTM A 120 steel pipe with a minimum diameter of 1-inch. • U, T, L, or C shape steel posts with a minimum weight of 1.35 lbs./ft. • Other steel posts having equivalent strength and bending resistance to the post sizes listed above. 11. Locate silt fences on contour as much as possible, except at the ends of the fence, where the fence shall be turned uphill such that the silt fence captures the runoff water and prevents water from flowing around the end of the fence. 12. If the fence must cross contours, with the exception of the ends of the fence, place gravel check dams perpendicular to the back of the fence to minimize concentrated flow and erosion. The slope of the fence line where contours must be crossed shall not be steeper than 3H:1 V. • Gravel check dams shall be approximately 1-foot deep at the back of the fence. Gravel check dams shall be continued perpendicular to the fence at the same elevation until the top of the check dam intercepts the ground surface behind the fence. • Gravel check dams shall consist of crushed surfacing base course, gravel backfill for walls, or shoulder ballast. Gravel check dams shall be located every 10 feet along the fence where the fence must cross contours. • Refer to Figure 4.2.13 for slicing method details. Silt fence installation using the slicing method specifications: Volume II—Construction Stormwater Pollution Prevention -December 2014 4-92 1. The base of both end posts must be at least 2-to 4-inches above the top of the filter fabric on the middle posts for ditch checks to drain properly. Use a hand level or string level, if necessary, to mark base points before installation. 2. Install posts 3-to 4-feet apart in critical retention areas and 6-to 7- feet apart in standard applications. 3. Install posts 24-inches deep on the downstream side of the silt fence, and as close as possible to the filter fabric, enabling posts to support the filter fabric from upstream water pressure. 4. Install posts with the nipples facing away from the filter fabric. 5. Attach the filter fabric to each post with three ties, all spaced within the top 8-inches of the filter fabric. Attach each tie diagonally 45 degrees through the filter fabric, with each puncture at least 1-inch vertically apart. Each tie should be positioned to hang on a post nipple when tightening to prevent sagging. 6. Wrap approximately 6-inches of fabric around the end posts and secure with 3 ties. 7. No more than 24-inches of a 36-inch filter fabric is allowed above ground level. Compact the soil immediately next to the filter fabric with the front wheel of the tractor, skid steer, or roller exerting at least 60 pounds per square inch. Compact the upstream side first and then each side twice for a total of four trips. Check and correct the silt fence installation for any deviation before compaction. Use a flat-bladed shovel to tuck fabric deeper into the ground if necessary. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-93 Ponding height POST SPACING: max.24- 7'max.on open runs 4'max.on pooling areas ------------ ---------------Top of Fabric 117177177 Bit Attach fabric to upstream side of post [O�8• FLOW Drive over each side of POST DEPTH: silt fence 2 to 4 times As much below ground with device exerting as fabric above ground 6o p.s.1.or greater 100%cwnpactloj' te0%compaCrall Diagonal attachment doubles strength. /\\\71 /—\/ �/�\ ATTACHMENT DETAILS: /�\ •Gather fabric at posts,if needed. �\\\ P P top•Utilize three ties per oat,all within t 8"of fabric. �\\\ •Position each lie diagonally,puncturing holes vertically ✓/\\/\\/\�/ \� a minimum of 1•apart. \ \ •Hang each tie on a post nipple and tighten secrsely. No more than 24"of a 36"fabric Use cable ties(50lbs)or sort wife. is allowed above ground. Roll of silt fence t� Operation Post installed after Li 01 compaction Fabric Oabove ground Silt Fence M. 200-300mm Horizontal chisel point Slicing blade (76 mm width) (1 S mm width) Completed Installation Vibratory plow is not acceptable because of horizontal compaction Figure 4.2.13—Silt Fence Installation by Slicing Method Maintenance • Repair any damage immediately. Standards • Intercept and convey all evident concentrated flows uphill of the silt fence to a sediment pond. • Check the uphill side of the fence for signs of the fence clogging and acting as a barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace the fence or remove the trapped sediment. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-94 • Remove sediment deposits when the deposit reaches approximately one-third the height of the silt fence, or install a second silt fence. • Replace filter fabric that has deteriorated due to ultraviolet breakdown. BMP C234: Vegetated Strip Puy^pose Vegetated strips reduce the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use • Vegetated strips may be used downslope of all disturbed areas. • Vegetated strips are not intended to treat concentrated flows, nor are they intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to a sediment pond. The only circumstance in which overland flow can be treated solely by a strip, rather than by a sediment pond, is when the following criteria are met (see Table 4.2.4): Table 4.2.4 Contributing Drainage Area for Vegetated Strips Average Contributing Average Contributing area Max Contributing area Sloe Percent Sloe area Flow path Length 1.5H:1 V or flatter 67%or flatter 100 feet 2H:1 V or flatter 50%or flatter 115 feet 4H:1V or flatter 25%or flatter 150 feet 6H:1 V or flatter 16.7%or flatter 200 feet 1 OH:1 V or flatter 10%or flatter 250 feet Design and The vegetated strip shall consist of a minimum of a 25-foot flowpath Installation length continuous strip of dense vegetation with topsoil. Grass- Specifications covered, landscaped areas are generally not adequate because the volume of sediment overwhelms the grass. Ideally, vegetated strips shall consist of undisturbed native growth with a well-developed soil that allows for infiltration of runoff. • The slope within the strip shall not exceed 4H:IV. • The uphill boundary of the vegetated strip shall be delineated with clearing limits. Maintenance Any areas damaged by erosion or construction activity shall be Standards seeded immediately and protected by mulch. • If more than 5 feet of the original vegetated strip width has had vegetation removed or is being eroded, sod must be installed. • If there are indications that concentrated flows are traveling across the buffer, surface water controls must be installed to reduce the flows Volume II—Construction Stormwater Pollution Prevention -December 2014 4-95 entering the buffer, or additional perimeter protection must be installed. BMP C235: Wattles Purpose Wattles are temporary erosion and sediment control barriers consisting of straw, compost, or other material that is wrapped in biodegradable tubular plastic or similar encasing material. They reduce the velocity and can spread the flow of rill and sheet runoff, and can capture and retain sediment. Wattles are typically 8 to 10 inches in diameter and 25 to 30 feet in length. Wattles are placed in shallow trenches and staked along the contour of disturbed or newly constructed slopes. See Figure 4.2.14 for typical construction details. WSDOT Standard Plan I-30.30-00 also provides information on Wattles (hM2://www.wsdot.wa.gov/Design/Standards/Plans.htm#Section Conditions of Use Use wattles: • In disturbed areas that require immediate erosion protection. • On exposed soils during the period of short construction delays, or over winter months. • On slopes requiring stabilization until permanent vegetation can be established. • The material used dictates the effectiveness period of the wattle. Generally, Wattles are typically effective for one to two seasons. • Prevent rilling beneath wattles by properly entrenching and abutting wattles together to prevent water from passing between them. Design Criteria Install wattles perpendicular to the flow direction and parallel to the slope contour. • Narrow trenches should be dug across the slope on contour to a depth of 3-to 5-inches on clay soils and soils with gradual slopes. On loose soils, steep slopes, and areas with high rainfall, the trenches should be dug to a depth of 5-to 7- inches, or 1/2 to 2/3 of the thickness of the wattle. • Start building trenches and installing wattles from the base of the slope and work up. Spread excavated material evenly along the uphill slope and compacted using hand tamping or other methods. • Construct trenches at intervals of 10-to 25-feet depending on the steepness of the slope, soil type, and rainfall. The steeper the slope the closer together the trenches. • Install the wattles snugly into the trenches and abut tightly end to end. Do not overlap the ends. • Install stakes at each end of the wattle, and at 4-foot centers along entire length of wattle. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-96 • If required, install pilot holes for the stakes using a straight bar to drive holes through the wattle and into the soil. • Wooden stakes should be approximately 3/4 x 3/4 x 24 inches min. Willow cuttings or 3/8-inch rebar can also be used for stakes. • Stakes should be driven through the middle of the wattle, leaving 2 to 3 inches of the stake protruding above the wattle. Maintenance Wattles may require maintenance to ensure they are in contact with Standards soil and thoroughly entrenched, especially after significant rainfall on steep sandy soils. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-97 T-4' Straw Rolls Must \�\ Be Placed Along AjVA Slope Contours j j Adjacent rolls shall \ tightly abut \y Spacing Dependson Soil Slope Steepness e and /\//\\i Sediment,organic matter, \\\\/ and native seeds are /\ captured behind the rolls. 3"-5"(75-125mm) (200-250mm) \ Live Stake �,\\ 1" X 1" Stake not to scale (25 x 25mm) NOTE: 1.Straw roll installation requires the placement and secure staking of the roll in a trench,Y-5"(75-125mm) deep,dug on contour. runoff must not be allowed to run under or around roll. Figure 4.2.14—Wattles Volume II— Construction Stormwater Pollution Prevention -December 2014 4-98 Stormwater Pollution Prevention Plan Appendix C — Alternative BMPs The following includes a list of possible alternative BMPs for each of the 12 elements not described in the main SWPPP text. This list can be referenced in the event a BMP for a specific element is not functioning as designed and an alternative BMP needs to be implemented. Element#1 -Mark Clearing Limits BMP C 102 Buffer Zones Element#2 -Establish Construction Access BMP C106 Wheel Wash Element#3 - Control Flow Rates BMP C203 Water Bars BMP C235 Wattles BMP C240 Sediment Trap BMP C241 Sediment Pond Element#4 -Install Sediment Controls BMP C231 Brush Barrier BMP C232 Gravel Filter Berm BMP C234 Vegetated Strip BMP C235 Wattles BMP C240 Sediment Trap BMP C241 Sediment Pond Element#5 - Stabilize Soils BMP C 122 Nets & Blankets BMP C 124 Sodding BMP C 126 Polyacrylamides for Soil Erosion Protection BMP C130 Surface Roughening BMP C 131 Gradient Terraces Element#6 - Protect Slopes BMP C 122 Nets & Blankets BMP C130 Surface Roughening BMP C 131 Gradient Terraces Element#7—Protect Drain Inlets Element#8 - Stabilize Channels and Outlets BMP C 122 Nets & Blankets BMP C202 Channel Lining BMP C208 Triangular Silt Dike 24 Stormwater Pollution Prevention Plan Element#9—Control Pollutants BMP C 154 Concrete Washout Area Element#10 - Control Dewatering BMP C203 Water Bars BMP C206 Level Spreader BMP C236 Vegetated Filtration Element#11 —Maintain BMP's Element#12 —Manage the Project Element#13—Protect Low Impact Development BMP C 102 Buffer Zones BMP C208 Triangular Silt Dike BMP C231 Brush Barrier BMP C234 Vegetated Strip 25 Stormwater Pollution Prevention Plan Appendix D — General Permit 26 Issuance Date: November 18, 2015 Effective Date: January 1, 2016 Expiration Date: December 31,2020 CONSTRUCTION STORMWATER GENERAL PERMIT National Pollutant Discharge Elimination System (NPDES) and State Waste Discharge General Permit for Stormwater Discharges Associated with Construction Activity State of Washington Department of Ecology Olympia, Washington 98504 In compliance with the provisions of Chapter 90.48 Revised Code of Washington (State of Washington Water Pollution Control Act) and Title 33 United States Code, Section 1251 et seq. The Federal Water Pollution Control Act (The Clean Water Act) Until this permit expires, is modified, or revoked, Permittees that have properly obtained coverage under this general permit are authorized to discharge ui accordance with the special and general conditions that follow. Hea hbr R. Bartlett Wate,-Quality Program Manager Washington State Department of Ecology TABLE OF CONTENTS LISTOF TABLES...........................................................................................................................3 SUMMARY OF PERMIT REPORT SUBMITTALS.....................................................................4 SPECIAL CONDITIONS................................................................................................................5 S 1. PERMIT COVERAGE........................................................................................................5 S2. APPLICATION REQUIREMENTS ...................................................................................8 S3. COMPLIANCE WITH STANDARDS.............................................................................12 S4. MONITORING REQUIREMENTS, BENCHMARKS, AND REPORTINGTRIGGERS ................................................................................................13 S5. REPORTING AND RECORDKEEPING REQUIREMENTS .........................................20 S6. PERMIT FEES...................................................................................................................23 S7. SOLID AND LIQUID WASTE DISPOSAL ....................................................................23 S8. DISCHARGES TO 303(d) OR TMDL WATERBODIES................................................23 S9. STORMWATER POLLUTION PREVENTION PLAN...................................................27 S 10. NOTICE OF TERMINATION.........................................................................................37 GENERALCONDITIONS ...........................................................................................................38 G1. DISCHARGE VIOLATIONS ...........................................................................................38 G2. SIGNATORY REQUIREMENTS.....................................................................................38 G3. RIGHT OF INSPECTION AND ENTRY.........................................................................39 G4. GENERAL PERMIT MODIFICATION AND REVOCATION......................................39 G5. REVOCATION OF COVERAGE UNDER THE PERMIT .............................................39 G6. REPORTING A CAUSE FOR MODIFICATION............................................................40 G7. COMPLIANCE WITH OTHER LAWS AND STATUTES.............................................40 G8. DUTY TO REAPPLY.......................................................................................................40 G9. TRANSFER OF GENERAL PERMIT COVERAGE.......................................................41 G10. REMOVED SUBSTANCES .............................................................................................41 G11. DUTY TO PROVIDE INFORMATION...........................................................................41 G12. OTHER REQUIREMENTS OF 40 CFR...........................................................................41 G 13. ADDITIONAL MONITORING........................................................................................41 G14. PENALTIES FOR VIOLATING PERMIT CONDITIONS .............................................41 G15. UPSET...............................................................................................................................42 G16. PROPERTY RIGHTS........................................................................................................42 Construction Stormwater General Permit Page 2 G17. DUTY TO COMPLY ........................................................................................................42 G18. TOXIC POLLUTANTS.....................................................................................................42 G19. PENALTIES FOR TAMPERING.....................................................................................43 G20. REPORTING PLANNED CHANGES .............................................................................43 G21. REPORTING OTHER INFORMATION..........................................................................43 G22. REPORTING ANTICIPATED NON-COMPLIANCE.....................................................43 G23. REQUESTS TO BE EXCLUDED FROM COVERAGE UNDER THE PERMIT..........44 G24. APPEALS ..........................................................................................................................44 G25. SEVERABILITY...............................................................................................................44 G26. BYPASS PROHIBITED....................................................................................................44 APPENDIX A—DEFINITIONS...................................................................................................47 APPENDIX B—ACRONYMS .....................................................................................................55 LIST OF TABLES Table 1: Summary of Required Submittals................................................................................... 4 Table 2: Summary of Required On-site Documentation............................................................... 4 Table 3: Summary of Primary Monitoring Requirements .......................................................... 15 Table 4: Monitoring and Reporting Requirements ..................................................................... 17 Table 5: Turbidity, Fine Sediment& Phosphorus Sampling and Limits for 303(d)-Listed Waters.................................................................................................... 25 Table 6: pH Sampling and Limits for 303(d)-Listed Waters...................................................... 26 Construction Stormwater General Permit Page 3 SUMMARY OF PERMIT REPORT SUBMITTALS Refer to the Special and General Conditions within this permit for additional submittal requirements. Appendix A provides a list of definitions. Appendix B provides a list of acronyms. Table 1: Summary of Required Submittals Permit Submittal Frequency First Submittal Date Section S5.A and High Turbidity/Transparency Phone As Necessary Within 24 hours S8 Reporting S5.B Discharge Monitoring Report Monthly* Within 15 days following the end of each month S5.F and Noncompliance Notification — As necessary Within 24-hours S8 Telephone Notification S5.F Noncompliance Notification — As necessary Within 5 Days of non- Written Report compliance S9.0 Request for Chemical Treatment As necessary Written approval from Form Ecology is required prior to using chemical treatment (with the exception of dry ice or CO2 to adjust pH) G2 Notice of Change in Authorization As necessary G6 Permit Application for Substantive As necessary Changes to the Discharge G8 Application for Permit Renewal 1/permit cycle No later than 180 days before expiration G9 Notice of Permit Transfer As necessary G20 Notice of Planned Changes As necessary G22 Reporting Anticipated Non- As necessary compliance SPECIAL NOTE: *Permittees must submit electronic Discharge Monitoring Reports(DMRs)to the Washington State Department of Ecology monthly,regardless of site discharge,for the full duration of permit coverage.Refer to Section S5.13 of this General Permit for more specific information regarding DMRs. Table 2: Summary of Required On-site Documentation Document Title Permit Conditions Permit Coverage Letter See Conditions S2, S5 Construction Stormwater General Permit See Conditions S2, S5 Site Log Book See Conditions S4, S5 Stormwater Pollution Prevention Plan (SWPPP) See Conditions S9, S5 Construction Stormwater General Permit Page 4 SPECIAL CONDITIONS S1. PERMIT COVERAGE A. Permit Area This Construction Stormwater General Permit(CSWGP) covers all areas of Washington State, except for federal operators and Indian Country as specified in Special Condition S 1.E.3. B. Operators Required to Seek Coverage Under this General Permit: 1. Operators of the following construction activities are required to seek coverage under this CSWGP: a. Clearing, grading and/or excavation that results in the disturbance of one or more acres (including off-site disturbance acreage authorized in S 1.C.2) and discharges stormwater to surface waters of the State; and clearing, grading and/or excavation on sites smaller than one acre that are part of a larger common plan of development or sale, if the common plan of development or sale will ultimately disturb one acre or more and discharge stormwater to surface waters of the State. i. This includes forest practices (including,but not limited to, class IV conversions) that are part of a construction activity that will result in the disturbance of one or more acres, and discharge to surface waters of the State (that is, forest practices that prepare a site for construction activities); and b. Any size construction activity discharging stormwater to waters of the State that the Washington State Department of Ecology(Ecology): i. Determines to be a significant contributor of pollutants to waters of the State of Washington. ii. Reasonably expects to cause a violation of any water quality standard. 2. Operators of the following activities are not required to seek coverage under this CSWGP (unless specifically required under Special Condition S1.B.l.b. above): a. Construction activities that discharge all stormwater and non-stormwater to ground water, sanitary sewer, or combined sewer, and have no point source discharge to either surface water or a storm sewer system that drains to surface waters of the State. b. Construction activities covered under an Erosivity Waiver(Special Condition S2.C). c. Routine maintenance that is performed to maintain the original line and grade, hydraulic capacity, or original purpose of a facility. Construction Stormwater General Permit Page 5 C. Authorized Discharges: 1. Stormwater Associated with Construction Activity. Subject to compliance with the terms and conditions of this permit, Permittees are authorized to discharge stormwater associated with construction activity to surface waters of the State or to a storm sewer system that drains to surface waters of the State. (Note that"surface waters of the State"may exist on a construction site as well as off site; for example, a creek running through a site.) 2. Stormwater Associated with Construction Support Activity. This permit also authorizes stormwater discharge from support activities related to the permitted construction site (for example, an on-site portable rock crusher, off-site equipment staging yards, material storage areas, borrow areas, etc.)provided: a. The support activity relates directly to the permitted construction site that is required to have an NPDES permit; and b. The support activity is not a commercial operation serving multiple unrelated construction projects, and does not operate beyond the completion of the construction activity; and c. Appropriate controls and measures are identified in the Stormwater Pollution Prevention Plan (SWPPP) for the discharges from the support activity areas. 3. Non-Stormwater Discharges. The categories and sources of non-stormwater discharges identified below are authorized conditionally,provided the discharge is consistent with the terms and conditions of this permit: a. Discharges from fire-fighting activities. b. Fire hydrant system flushing. c. Potable water, including uncontaminated water line flushing. d. Hydrostatic test water. e. Uncontaminated air conditioning or compressor condensate. f. Uncontaminated ground water or spring water. g. Uncontaminated excavation dewatering water(in accordance with S9.D.10). h. Uncontaminated discharges from foundation or footing drains. i. Uncontaminated water used to control dust. Permittees must minimize the amount of dust control water used. j. Routine external building wash down that does not use detergents. k. Landscape irrigation water. The SWPPP must adequately address all authorized non-stormwater discharges, except for discharges from fire-fighting activities, and must comply with Special Condition S3. Construction Stormwater General Permit Page 6 At a minimum, discharges from potable water(including water line flushing), fire hydrant system flushing, and pipeline hydrostatic test water must undergo the following: dechlorination to a concentration of 0.1 parts per million (ppm) or less, and pH adjustment to within 6.5 — 8.5 standard units (su), if necessary. D. Prohibited Discharges: The following discharges to waters of the State, including ground water, are prohibited. 1. Concrete wastewater. 2. Wastewater from washout and clean-up of stucco,paint, form release oils, curing compounds and other construction materials. 3. Process wastewater as defined by 40 Code of Federal Regulations (CFR) 122.2 (see Appendix A of this permit). 4. Slurry materials and waste from shaft drilling, including process wastewater from shaft drilling for construction of building, road, and bridge foundations unless managed according to Special Condition S9.D.9.j. 5. Fuels, oils, or other pollutants used in vehicle and equipment operation and maintenance. 6. Soaps or solvents used in vehicle and equipment washing. 7. Wheel wash wastewater, unless managed according to Special Condition S9.D.9. 8. Discharges from dewatering activities, including discharges from dewatering of trenches and excavations, unless managed according to Special Condition S9.D.10. E. Limits on Coverage Ecology may require any discharger to apply for and obtain coverage under an individual permit or another more specific general permit. Such alternative coverage will be required when Ecology determines that this CSWGP does not provide adequate assurance that water quality will be protected, or there is a reasonable potential for the project to cause or contribute to a violation of water quality standards. The following stormwater discharges are not covered by this permit: 1. Post-construction stormwater discharges that originate from the site after completion of construction activities and the site has undergone final stabilization. 2. Non-point source silvicultural activities such as nursery operations, site preparation, reforestation and subsequent cultural treatment, thinning, prescribed burning, pest and fire control, harvesting operations, surface drainage, or road construction and maintenance, from which there is natural runoff as excluded in 40 CFR Subpart 122. 3. Stormwater from any federal operator. Construction Stormwater General Permit Page 7 4. Stormwater from facilities located on"Indian Country" as defined in 18 U.S.C.§1151, except portions of the Puyallup Reservation as noted below. Indian Country includes: a. All land within any Indian Reservation notwithstanding the issuance of any patent, and, including rights-of-way running through the reservation. This includes all federal, tribal, and Indian and non-Indian privately owned land within the reservation. b. All off-reservation Indian allotments, the Indian titles to which have not been extinguished, including rights-of-way running through the same. c. All off-reservation federal trust lands held for Native American Tribes. Puyallup Exception: Following the Puyallup Tribes of Indians Land Settlement Act of 1989, 25 U.S.C. §1773; the permit does apply to land within the Puyallup Reservation except for discharges to surface water on land held in trust by the federal government. 5. Stormwater from any site covered under an existing NPDES individual permit in which stormwater management and/or treatment requirements are included for all stormwater discharges associated with construction activity. 6. Stormwater from a site where an applicable Total Maximum Daily Load(TMDL) requirement specifically precludes or prohibits discharges from construction activity. S2. APPLICATION REQUIREMENTS A. Permit Application Forms 1. Notice of Intent Form/Timeline a. Operators of new or previously unpermitted construction activities must submit a complete and accurate permit application (Notice of Intent, or NOI)to Ecology. b. Operators must apply using the electronic application form(NOI) available on Ecology's website http://www.ecy.wa.goy/programs/wq/stormwater/ construction/index.html. Permittees unable to submit electronically(for example, those who do not have an internet connection)must contact Ecology to request a waiver and obtain instructions on how to obtain a paper NOI. Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 Construction Stormwater General Permit Page 8 c. The operator must submit the NOI at least 60 days before discharging stormwater from construction activities and must submit it on or before the date of the first public notice (see Special Condition S2.B below for details). The 30- day public comment period begins on the publication date of the second public notice. Unless Ecology responds to the complete application in writing, based on public comments, or any other relevant factors, coverage under the general permit will automatically commence on the thirty-first day following receipt by Ecology of a completed NOI, or the issuance date of this permit, whichever is later; unless Ecology specifies a later date in writing as required by WAC173- 226-200(2). d. If an applicant intends to use a Best Management Practice (BMP) selected on the basis of Special Condition S9.C.4 ("demonstrably equivalent"BMPs), the applicant must notify Ecology of its selection as part of the NOI. In the event the applicant selects BMPs after submission of the NOI, it must provide notice of the selection of an equivalent BMP to Ecology at least 60 days before intended use of the equivalent BMP. e. Permittees must notify Ecology regarding any changes to the information provided on the NOI by submitting an updated NOI. Examples of such changes include, but are not limited to: i. Changes to the Permittee's mailing address, ii. Changes to the on-site contact person information, and iii. Changes to the area/acreage affected by construction activity. f. Applicants must notify Ecology if they are aware of contaminated soils and/or groundwater associated with the construction activity. Provide detailed information with the NOI (as known and readily available) on the nature and extent of the contamination (concentrations, locations, and depth), as well as pollution prevention and/or treatment BMPs proposed to control the discharge of soil and/or groundwater contaminants in stormwater. Examples of such detail may include,but are not limited to: i. List or table of all known contaminants with laboratory test results showing concentration and depth, ii. Map with sample locations, iii. Temporary Erosion and Sediment Control (TESC)plans, iv. Related portions of the Stormwater Pollution Prevention Plan (SWPPP) that address the management of contaminated and potentially contaminated construction stormwater and dewatering water, V. Dewatering plan and/or dewatering contingency plan. Construction Stormwater General Permit Page 9 2. Transfer of Coverage Form The Permittee can transfer current coverage under this permit to one or more new operators, including operators of sites within a Common Plan of Development, provided the Permittee submits a Transfer of Coverage Form in accordance with General Condition G9. Transfers do not require public notice. B. Public Notice For new or previously unpermitted construction activities, the applicant must publish a public notice at least one time each week for two consecutive weeks, at least 7 days apart, in a newspaper with general circulation in the county where the construction is to take place. The notice must contain: 1. A statement that"The applicant is seeking coverage under the Washington State Department of Ecology's Construction Stormwater NPDES and State Waste Discharge General Permit". 2. The name, address and location of the construction site. 3. The name and address of the applicant. 4. The type of construction activity that will result in a discharge (for example, residential construction, commercial construction, etc.), and the number of acres to be disturbed. 5. The name of the receiving water(s) (that is, the surface water(s)to which the site will discharge), or, if the discharge is through a storm sewer system, the name of the operator of the system. 6. The statement: "Any persons desiring to present their views to the Washington State Department of Ecology regarding this application, or interested in Ecology's action on this application, may notify Ecology in writing no later than 30 days of the last date of publication of this notice. Ecology reviews public comments and considers whether discharges from this project would cause a measurable change in receiving water quality, and, if so,whether the project is necessary and in the overriding public interest according to Tier II antidegradation requirements under WAC 173-201A-320. Comments can be submitted to: Department of Ecology, PO Box 47696, Olympia, Washington 98504-7696 Attn: Water Quality Program, Construction Stormwater." Construction Stormwater General Permit Page 10 C. Erosivity Waiver Construction site operators may qualify for an erosivity waiver from the CSWGP if the following conditions are met: 1. The site will result in the disturbance of fewer than 5 acres and the site is not a portion of a common plan of development or sale that will disturb 5 acres or greater. 2. Calculation of Erosivity"R"Factor and Regional Timeframe: a. The project's rainfall erosivity factor ("R"Factor) must be less than 5 during the period of construction activity, as calculated(see the CSWGP homepage http://www.ccy.wa.goy/programs/wg/stonnwater/construction/index.html for a link to the EPA's calculator and step by step instructions on computing the "R" Factor in the EPA Erosivity Waiver Fact Sheet). The period of construction activity starts when the land is first disturbed and ends with final stabilization. In addition: b. The entire period of construction activity must fall within the following timeframes: i. For sites west of the Cascades Crest: June 15 — September 15. ii. For sites east of the Cascades Crest, excluding the Central Basin: June 15 —October 15. iii. For sites east of the Cascades Crest,within the Central Basin: no additional timeframe restrictions apply. The Central Basin is defined as the portions of Eastern Washington with mean annual precipitation of less than 12 inches. For a map of the Central Basin(Average Annual Precipitation Region 2), refer to hqp://www.ecy.wa.goy/programs/wq/stonnwater/ constiruction/resourcesguidance.html. 3. Construction site operators must submit a complete Erosivity Waiver certification form at least one week before disturbing the land. Certification must include statements that the operator will: a. Comply with applicable local stormwater requirements; and b. Implement appropriate erosion and sediment control BMPs to prevent violations of water quality standards. 4. This waiver is not available for facilities declared significant contributors of pollutants as defined in Special Condition S I.B.Lb. or for any size construction activity that could reasonably expect to cause a violation of any water quality standard as defined in Special Condition S 1.13.Lb.ii. 5. This waiver does not apply to construction activities which include non- stormwater discharges listed in Special Condition S 1.C.3. Construction Stormwater General Permit Page 11 6. If construction activity extends beyond the certified waiver period for any reason, the operator must either: a. Recalculate the rainfall erosivity"R" factor using the original start date and a new projected ending date and, if the "R" factor is still under 5 and the entire project falls within the applicable regional timeframe in Special Condition S2.C.2.b, complete and submit an amended waiver certification form before the original waiver expires; or b. Submit a complete permit application to Ecology in accordance with Special Condition S2.A and B before the end of the certified waiver period. S3. COMPLIANCE WITH STANDARDS A. Discharges must not cause or contribute to a violation of surface water quality standards (Chapter 173-201A WAC), ground water quality standards (Chapter 173-200 WAC), sediment management standards (Chapter 173-204 WAC), and human health-based criteria in the National Toxics Rule (40 CFR Part 131.36). Discharges not in compliance with these standards are not authorized. B. Prior to the discharge of stormwater and non-stormwater to waters of the State, the Permittee must apply all known, available, and reasonable methods of prevention, control, and treatment(AKART). This includes the preparation and implementation of an adequate SWPPP, with all appropriate BMPs installed and maintained in accordance with the SWPPP and the terms and conditions of this permit. C. Ecology presumes that a Permittee complies with water quality standards unless discharge monitoring data or other site-specific information demonstrates that a discharge causes or contributes to a violation of water quality standards, when the Permittee complies with the following conditions. The Permittee must fully: 1. Comply with all permit conditions, including planning, sampling, monitoring, reporting, and recordkeeping conditions. 2. Implement stormwater BMPs contained in stormwater management manuals published or approved by Ecology, or BMPs that are demonstrably equivalent to BMPs contained in stormwater technical manuals published or approved by Ecology, including the proper selection, implementation, and maintenance of all applicable and appropriate BMPs for on-site pollution control. (For purposes of this section, the stormwater manuals listed in Appendix 10 of the Phase I Municipal Stormwater Permit are approved by Ecology.) D. Where construction sites also discharge to ground water, the ground water discharges must also meet the terms and conditions of this CSWGP. Permittees who discharge to ground water through an injection well must also comply with any applicable requirements of the Underground Injection Control (UIC)regulations, Chapter 173-218 WAC. Construction Stormwater General Permit Page 12 S4. MONITORING REQUIREMENTS, BENCHMARKS,AND REPORTING TRIGGERS A. Site Log Book The Permittee must maintain a site log book that contains a record of the implementation of the SWPPP and other permit requirements, including the installation and maintenance of BMPs, site inspections, and stormwater monitoring. B. Site Inspections The Permittee's site inspections must include all areas disturbed by construction activities, all BMPs, and all stormwater discharge points under the Permittee's operational control. (See Special Conditions S4.B.3 and BA below for detailed requirements of the Permittee's Certified Erosion and Sediment Control Lead [CESCL].) Construction sites one acre or larger that discharge stormwater to surface waters of the State must have site inspections conducted by a certified CESCL. Sites less than one acre may have a person without CESCL certification conduct inspections. 1. The Permittee must examine stormwater visually for the presence of suspended sediment, turbidity, discoloration, and oil sheen. The Permittee must evaluate the effectiveness of BMPs and determine if it is necessary to install, maintain, or repair BMPs to improve the quality of stormwater discharges. Based on the results of the inspection, the Permittee must correct the problems identified by: a. Reviewing the SWPPP for compliance with Special Condition S9 and making appropriate revisions within 7 days of the inspection. b. Immediately beginning the process of fully implementing and maintaining appropriate source control and/or treatment BMPs as soon as possible, addressing the problems no later than within 10 days of the inspection. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when an extension is requested by a Permittee within the initial 10-day response period. c. Documenting BMP implementation and maintenance in the site log book. 2. The Permittee must inspect all areas disturbed by construction activities, all BMPs, and all stormwater discharge points at least once every calendar week and within 24 hours of any discharge from the site. (For purposes of this condition, individual discharge events that last more than one day do not require daily inspections. For example, if a stormwater pond discharges continuously over the course of a week, only one inspection is required that week.) The Permittee may reduce the inspection frequency for temporarily stabilized, inactive sites to once every calendar month. Construction Stormwater General Permit Page 13 3. The Permittee must have staff knowledgeable in the principles and practices of erosion and sediment control. The CESCL(sites one acre or more) or inspector (sites less than one acre) must have the skills to assess the: a. Site conditions and construction activities that could impact the quality of stormwater, and b. Effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. 4. The SWPPP must identify the CESCL or inspector,who must be present on site or on-call at all times. The CESCL must obtain this certification through an approved erosion and sediment control training program that meets the minimum training standards established by Ecology(see BMP C 160 in the manual referred to in Special Condition S9.C.1 and 2). 5. The Permittee must summarize the results of each inspection in an inspection report or checklist and enter the report/checklist into, or attach it to, the site log book. At a minimum, each inspection report or checklist must include: a. Inspection date and time. b. Weather information, the general conditions during inspection and the approximate amount of precipitation since the last inspection, and precipitation within the last 24 hours. c. A summary or list of all implemented BMPs, including observations of all erosion/sediment control structures or practices. d. A description of the locations: i. Of BMPs inspected; ii. Of BMPs that need maintenance and why; iii. Of BMPs that failed to operate as designed or intended; and iv. Where additional or different BMPs are needed, and why. e. A description of stormwater discharged from the site. The Permittee must note the presence of suspended sediment, turbidity, discoloration, and oil sheen, as applicable. f. Any water quality monitoring performed during inspection. g. General comments and notes, including a brief description of any BMP repairs, maintenance or installations made following the inspection. h. A summary report and a schedule of implementation of the remedial actions that the Permittee plans to take if the site inspection indicates that the site is out of compliance. The remedial actions taken must meet the requirements of the SWPPP and the permit. Construction Stormwater General Permit Page 14 i. The name, title, and signature of the person conducting the site inspection, a phone number or other reliable method to reach this person, and the following statement: "I certify that this report is true, accurate, and complete to the best of my knowledge and belief." Table 3: Summary of Primary Monitoring Requirements Size of Soil Weekly Site Weekly Weekly Weekly pH CESCL Disturbancel Inspections Sampling w/ Sampling w/ Sampling2 Required for Turbidity Transparency Inspections? Meter Tube Sites that disturb Required Not Required Not Required Not Required No less than 1 acre, but are part of a larger Common Plan of Development Sites that disturb 1 Required Sampling Required — Required Yes acre or more, but either method' fewer than 5 acres Sites that disturb 5 Required Required Not Required' Required Yes acres or more ' Soil disturbance is calculated by adding together all areas that will be affected by construction activity. Construction activity means clearing,grading,excavation,and any other activity that disturbs the surface of the land,including ingress/egress from the site. 2 If construction activity results in the disturbance of 1 acre or more,and involves significant concrete work(1,000 cubic yards of poured over the life of a project)or the use of recycled concrete or engineered soils(soil amendments including but not limited to Portland cement-treated base[CTB],cement kiln dust[CKD], or fly ash),and stormwater from the affected area drains to surface waters of the State or to a storm sewer stormwater collection system that drains to other surface waters of the State,the Permittee must conduct pH sampling in accordance with Special Condition S4.13. 3 Sites with one or more acres,but fewer than 5 acres of soil disturbance,must conduct turbidity or transparency sampling in accordance with Special Condition S4.C. ' Sites equal to or greater than 5 acres of soil disturbance must conduct turbidity sampling using a turbidity meter in accordance with Special Condition S4.C. Construction Stormwater General Permit Page 15 C. Turbidity/Transparency Sampling Requirements 1. Sampling Methods a. If construction activity involves the disturbance of 5 acres or more, the Permittee must conduct turbidity sampling per Special Condition S4.C. b. If construction activity involves 1 acre or more but fewer than 5 acres of soil disturbance, the Permittee must conduct either transparency sampling or turbidity sampling per Special Condition S4.C. 2. Sampling Frequency a. The Permittee must sample all discharge points at least once every calendar week when stormwater(or authorized non-stormwater) discharges from the site or enters any on-site surface waters of the state (for example, a creek running through a site); sampling is not required on sites that disturb less than an acre. b. Samples must be representative of the flow and characteristics of the discharge. c. Sampling is not required when there is no discharge during a calendar week. d. Sampling is not required outside of normal working hours or during unsafe conditions. e. If the Permittee is unable to sample during a monitoring period, the Permittee must include a brief explanation in the monthly Discharge Monitoring Report (DMR). £ Sampling is not required before construction activity begins. g. The Permittee may reduce the sampling frequency for temporarily stabilized, inactive sites to once every calendar month. 3. Sampling Locations a. Sampling is required at all points where stormwater associated with construction activity(or authorized non-stormwater) is discharged off site, including where it enters any on-site surface waters of the state (for example, a creek running through a site). b. The Permittee may discontinue sampling at discharge points that drain areas of the project that are fully stabilized to prevent erosion. c. The Permittee must identify all sampling point(s) on the SWPPP site map and clearly mark these points in the field with a flag, tape, stake or other visible marker. d. Sampling is not required for discharge that is sent directly to sanitary or combined sewer systems. Construction Stormwater General Permit Page 16 e. The Permittee may discontinue sampling at discharge points in areas of the project where the Permittee no longer has operational control of the construction activity. 4. Sampling and Analysis Methods a. The Permittee performs turbidity analysis with a calibrated turbidity meter (turbidimeter) either on site or at an accredited lab. The Permittee must record the results in the site log book in nephelometric turbidity units (NTUs). b. The Permittee performs transparency analysis on site with a 13/4-inch-diameter, 60-centimeter(cm)-long transparency tube. The Permittee will record the results in the site log book in centimeters (cm). Table 4: Monitoring and Reporting Requirements Parameter Unit Analytical Method Sampling Benchmark Phone Frequency Value Reporting Trigger Value Turbidity NTU SM2130 Weekly, if 25 NTUs 250 NTUs discharging Transparency cm Manufacturer Weekly, if 33 cm 6 cm instructions, or discharging Ecology guidance 5. Turbidity/Transparency Benchmark Values and Reporting Triggers The benchmark value for turbidity is 25 NTUs or less. The benchmark value for transparency is 33 centimeters (cm). Note: Benchmark values do not apply to discharges to segments of water bodies on Washington State's 303(d) list (Category 5) for turbidity, fine sediment, or phosphorus; these discharges are subject to a numeric effluent limit for turbidity. Refer to Special Condition S8 for more information. a. Turbidity 26—249 NTUs, or Transparency 32 —7 cm: If the discharge turbidity is 26 to 249 NTUs; or if discharge transparency is less than 33 cm, but equal to or greater than 6 cm, the Permittee must: i. Review the SWPPP for compliance with Special Condition S9 and make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. ii. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible, addressing the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. Construction Stormwater General Permit Page 17 iii. Document BMP implementation and maintenance in the site log book. b. Turbidity 250 NTUs or greater, or Transparency 6 cm or less: If a discharge point's turbidity is 250 NTUs or greater, or if discharge transparency is less than or equal to 6 cm, the Permittee must complete the reporting and adaptive management process described below. i. Telephone or submit an electronic report to the applicable Ecology Region's Environmental Report Tracking System (ERTS) number (or through Ecology's Water Quality Permitting Portal [WQWebPortal] — Permit Submittals when the form is available)within 24 hours, in accordance with Special Condition S5.A. • Central Region (Okanogan, Chelan, Douglas, Kittitas, Yakima, Klickitat, Benton): (509) 575-2490 • Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400 • Northwest Region (Kitsap, Snohomish, Island, King, San Juan, Skagit, Whatcom): (425) 649-7000 • Southwest Region (Grays Harbor, Lewis, Mason, Thurston, Pierce, Clark, Cowlitz, Skamania, Wahkiakum, Clallam, Jefferson, Pacific): (360) 407-6300 Links to these numbers and the ERTS reporting page are located on the following web site: http://www.ecy.wa.gov/programs/wq/stonnwater/construction/index.html. ii. Review the SWPPP for compliance with Special Condition S9 and make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. iii. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible, addressing the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. iv. Document BMP implementation and maintenance in the site log book. V. Sample discharges daily until: a) Turbidity is 25 NTUs (or lower); or b) Transparency is 33 cm(or greater); or Construction Stormwater General Permit Page 18 c) The Permittee has demonstrated compliance with the water quality limit for turbidity: 1) No more than 5 NTUs over background turbidity, if background is less than 50 NTUs, or 2) No more than 10% over background turbidity, if background is 50 NTUs or greater; or d) The discharge stops or is eliminated. D. pH Sampling Requirements— Significant Concrete Work or Engineered Soils If construction activity results in the disturbance of 1 acre or more, and involves significant concrete work(significant concrete work means greater than 1000 cubic yards poured concrete used over the life of a project) or the use of recycled concrete or engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD], or fly ash), and stormwater from the affected area drains to surface waters of the State or to a storm sewer system that drains to surface waters of the State, the Permittee must conduct pH sampling as set forth below. Note: In addition, discharges to segments of water bodies on Washington State's 303(d) list (Category 5) for high pH are subject to a numeric effluent limit for pH; refer to Special Condition S8. 1. For sites with significant concrete work, the Permittee must begin the pH sampling period when the concrete is first poured and exposed to precipitation, and continue weekly throughout and after the concrete pour and curing period, until stormwater pH is in the range of 6.5 to 8.5 (su). 2. For sites with recycled concrete, the Permittee must begin the weekly pH sampling period when the recycled concrete is first exposed to precipitation and must continue until the recycled concrete is fully stabilized and stormwater pH is in the range of 6.5 to 8.5 (su). 3. For sites with engineered soils, the Permittee must begin the pH sampling period when the soil amendments are first exposed to precipitation and must continue until the area of engineered soils is fully stabilized. 4. During the applicable pH monitoring period defined above, the Permittee must obtain a representative sample of stormwater and conduct pH analysis at least once per week. 5. The Permittee must sample pH in the sediment trap/pond(s) or other locations that receive stormwater runoff from the area of significant concrete work or engineered soils before the stormwater discharges to surface waters. 6. The benchmark value for pH is 8.5 standard units. Anytime sampling indicates that pH is 8.5 or greater, the Permittee must either: Construction Stormwater General Permit Page 19 a. Prevent the high pH water(8.5 or above) from entering storm sewer systems or surface waters; or b. If necessary, adjust or neutralize the high pH water until it is in the range of pH 6.5 to 8.5 (su)using an appropriate treatment BMP such as carbon dioxide (CO2) sparging or dry ice. The Permittee must obtain written approval from Ecology before using any form of chemical treatment other than CO2 sparging or dry ice. 7. The Permittee must perform pH analysis on site with a calibrated pH meter,pH test kit, or wide range pH indicator paper. The Permittee must record pH sampling results in the site log book. S5. REPORTING AND RECORDKEEPING REQUIREMENTS A. High Turbidity Reporting Anytime sampling performed in accordance with Special Condition S4.0 indicates turbidity has reached the 250 NTUs or more (or transparency less than or equal to 6 cm) high turbidity reporting level, the Permittee must either call the applicable Ecology Region's Environmental Report Tracking System (ERTS) number by phone within 24 hours of analysis or submit an electronic ERTS report (or submit an electronic report through Ecology's Water Quality Permitting Portal (WQWebPortal)—Permit Submittals when the form is available). See the CSWGP web site for links to ERTS and the WQWebPortal: http://www.ecy.wa.gov/programs/wq/stonnwater/construction/ index.html. Also, see phone numbers in Special Condition S4.C.5.b.i. B. Discharge Monitoring Reports (DMRs) Permittees required to conduct water quality sampling in accordance with Special Conditions S4.0 (Turbidity/Transparency), S4.D (pH), S8 (303[d]/TMDL sampling), and/or G13 (Additional Sampling) must submit the results to Ecology. Permittees must submit monitoring data using Ecology's WQWebDMR web application accessed through Ecology's Water Quality Permitting Portal. To find out more information and to sign up for WQWebDMR go to: http://www.ecy.wa.gov/pro rg ams/ wq//permits/paris/portal.html. Permittees unable to submit electronically(for example, those who do not have an internet connection)must contact Ecology to request a waiver and obtain instructions on how to obtain a paper copy DMR at: Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 Permittees who obtain a waiver not to use WQWebDMR must use the forms provided to them by Ecology; submittals must be mailed to the address above. Permittees shall Construction Stormwater General Permit Page 20 submit DMR forms to be received by Ecology within 15 days following the end of each month. If there was no discharge during a given monitoring period, all Permittees must submit a DMR as required with"no discharge" entered in place of the monitoring results. DMRs are required for the full duration of permit coverage (from issuance date to termination). For more information, contact Ecology staff using information provided at the following web site: www.ecy.wa.gov/programs/wq/permits/paris/contacts.html. C. Records Retention The Permittee must retain records of all monitoring information(site log book, sampling results, inspection reports/checklists, etc.), Stormwater Pollution Prevention Plan, copy of the permit coverage letter(including Transfer of Coverage documentation), and any other documentation of compliance with permit requirements for the entire life of the construction project and for a minimum of three years following the termination of permit coverage. Such information must include all calibration and maintenance records, and records of all data used to complete the application for this permit. This period of retention must be extended during the course of any unresolved litigation regarding the discharge of pollutants by the Permittee or when requested by Ecology. D. Recording Results For each measurement or sample taken, the Permittee must record the following information: 1. Date, place, method, and time of sampling or measurement. 2. The first and last name of the individual who performed the sampling or measurement. 3. The date(s)the analyses were performed. 4. The first and last name of the individual who performed the analyses. 5. The analytical techniques or methods used. 6. The results of all analyses. E. Additional Monitoring by the Permittee If the Permittee monitors any pollutant more frequently than required by this permit using test procedures specified by Special Condition S4 of this permit, the results of this monitoring must be included in the calculation and reporting of the data submitted in the Permittee's DMR. F. Noncompliance Notification In the event the Permittee is unable to comply with any part of the terms and conditions of this permit, and the resulting noncompliance may cause a threat to human health or the environment(such as but not limited to spills of fuels or other materials, catastrophic pond or slope failure, and discharges that violate water quality standards), or exceed Construction Stormwater General Permit Page 21 numeric effluent limitations (see S8. Discharges to 303(d) or TMDL Waterbodies), the Permittee must, upon becoming aware of the circumstance: 1. Notify Ecology within 24-hours of the failure to comply by calling the applicable Regional office ERTS phone number(refer to Special Condition S4.C.5.b.i. or www.ecy.wa ,Lov/programs/wg/stortnwater/construction/turbidity.html for Regional ERTS phone numbers). 2. Immediately take action to prevent the discharge/pollution, or otherwise stop or correct the noncompliance, and, if applicable, repeat sampling and analysis of any noncompliance immediately and submit the results to Ecology within five (5) days of becoming aware of the violation. 3. Submit a detailed written report to Ecology within five (5) days, of the time the Permittee becomes aware of the circumstances,unless requested earlier by Ecology. The report must be submitted using Ecology's Water Quality Permitting Portal (WQWebPortal) - Permit Submittals,unless a waiver from electronic reporting has been granted according to S5.B. The report must contain a description of the noncompliance, including exact dates and times, and if the noncompliance has not been corrected, the anticipated time it is expected to continue; and the steps taken or planned to reduce, eliminate, and prevent reoccurrence of the noncompliance. The Permittee must report any unanticipated bypass and/or upset that exceeds any effluent limit in the permit in accordance with the 24-hour reporting requirement contained in 40 C.F.R. 122.41(1)(6). Compliance with these requirements does not relieve the Permittee from responsibility to maintain continuous compliance with the terms and conditions of this permit or the resulting liability for failure to comply. Upon request of the Permittee, Ecology may waive the requirement for a written report on a case-by- case basis, if the immediate notification is received by Ecology within 24 hours. G. Access to Plans and Records 1. The Permittee must retain the following permit documentation(plans and records) on site, or within reasonable access to the site, for use by the operator or for on-site review by Ecology or the local jurisdiction: a. General Permit b. Permit Coverage Letter c. Stormwater Pollution Prevention Plan (SWPPP) d. Site Log Book 2. The Permittee must address written requests for plans and records listed above (Special Condition S5.G.1) as follows: Construction Stormwater General Permit Page 22 a. The Permittee must provide a copy of plans and records to Ecology within 14 days of receipt of a written request from Ecology. b. The Permittee must provide a copy of plans and records to the public when requested in writing. Upon receiving a written request from the public for the Permittee's plans and records, the Permittee must either: i. Provide a copy of the plans and records to the requester within 14 days of a receipt of the written request; or ii. Notify the requester within 10 days of receipt of the written request of the location and times within normal business hours when the plans and records may be viewed; and provide access to the plans and records within 14 days of receipt of the written request; or iii. Within 14 days of receipt of the written request, the Permittee may submit a copy of the plans and records to Ecology for viewing and/or copying by the requester at an Ecology office, or a mutually agreed location. If plans and records are viewed and/or copied at a location other than at an Ecology office, the Permittee will provide reasonable access to copying services for which a reasonable fee may be charged. The Permittee must notify the requester within 10 days of receipt of the request where the plans and records may be viewed and/or copied. S6. PERMIT FEES The Permittee must pay permit fees assessed by Ecology. Fees for stormwater discharges covered under this permit are established by Chapter 173-224 WAC. Ecology continues to assess permit fees until the permit is terminated in accordance with Special Condition S 10 or revoked in accordance with General Condition G5. S7. SOLID AND LIQUID WASTE DISPOSAL The Permittee must handle and dispose of solid and liquid wastes generated by construction activity, such as demolition debris, construction materials, contaminated materials, and waste materials from maintenance activities, including liquids and solids from cleaning catch basins and other stormwater facilities, in accordance with: A. Special Condition S3, Compliance with Standards B. WAC 173-216-110 C. Other applicable regulations S8. DISCHARGES TO 303(d) OR TMDL WATERBODIES A. Sampling and Numeric Effluent Limits For Certain Discharges to 303(d)-listed Waterbodies Construction Stormwater General Permit Page 23 1. Permittees who discharge to segments of waterbodies listed as impaired by the State of Washington under Section 303(d) of the Clean Water Act for turbidity, fine sediment, high pH, or phosphorus, must conduct water quality sampling according to the requirements of this section, and Special Conditions S4.C.2.b-f and S4.C.3.b-d, and must comply with the applicable numeric effluent limitations in S&C and S&D. 2. All references and requirements associated with Section 303(d) of the Clean Water Act mean the most current listing by Ecology of impaired waters (Category 5)that exists on January 1, 2016, or the date when the operator's complete permit application is received by Ecology, whichever is later. B. Limits on Coverage for New Discharges to TMDL or 303(d)-listed Waters Operators of construction sites that discharge to a TMDL or 303(d)-listed waterbody are not eligible for coverage under this permit unless the operator: 1. Prevents exposing stormwater to pollutants for which the waterbody is impaired, and retains documentation in the SWPPP that details procedures taken to prevent exposure on site; or 2. Documents that the pollutants for which the waterbody is impaired are not present at the site, and retains documentation of this finding within the SWPPP; or 3. Provides Ecology with data indicating the discharge is not expected to cause or contribute to an exceedance of a water quality standard, and retains such data on site with the SWPPP. The operator must provide data and other technical information to Ecology that sufficiently demonstrate: a. For discharges to waters without an EPA-approved or-established TMDL, that the discharge of the pollutant for which the water is impaired will meet in- stream water quality criteria at the point of discharge to the waterbody; or b. For discharges to waters with an EPA-approved or-established TMDL, that there is sufficient remaining wasteload allocation in the TMDL to allow construction stormwater discharge and that existing dischargers to the waterbody are subject to compliance schedules designed to bring the waterbody into attainment with water quality standards. Operators of construction sites are eligible for coverage under this permit if Ecology issues permit coverage based upon an affirmative determination that the discharge will not cause or contribute to the existing impairment. C. Sampling and Numeric Effluent Limits for Discharges to Water Bodies on the 303(d) List for Turbidity, Fine Sediment, or Phosphorus 1. Permittees who discharge to segments of water bodies on the 303(d) list (Category 5) for turbidity, fine sediment, or phosphorus must conduct turbidity sampling in accordance with Special Condition S4.C.2 and comply with either of the numeric effluent limits noted in Table 5 below. Construction Stormwater General Permit Page 24 2. As an alternative to the 25 NTUs effluent limit noted in Table 5 below (applied at the point where stormwater [or authorized non-stormwater] is discharged off-site), Permittees may choose to comply with the surface water quality standard for turbidity. The standard is: no more than 5 NTUs over background turbidity when the background turbidity is 50 NTUs or less, or no more than a 10% increase in turbidity when the background turbidity is more than 50 NTUs. In order to use the water quality standard requirement, the sampling must take place at the following locations: a. Background turbidity in the 303(d)-listed receiving water immediately upstream (upgradient) or outside the area of influence of the discharge. b. Turbidity at the point of discharge into the 303(d)-listed receiving water, inside the area of influence of the discharge. 3. Discharges that exceed the numeric effluent limit for turbidity constitute a violation of this permit. 4. Permittees whose discharges exceed the numeric effluent limit shall sample discharges daily until the violation is corrected and comply with the non- compliance notification requirements in Special Condition S5.F. Table 5: Turbidity, Fine Sediment & Phosphorus Sampling and Limits for 303(d)-Listed Waters Parameter identified Parameter Unit Analytical Sampling Numeric Effluent in 303(d) listing Sampled Method Frequency Limit' • Turbidity Turbidity NTU SM2130 Weekly, if 25 NTUs, at the • Fine Sediment discharging point where • Phosphorus stormwater is discharged from the site; OR In compliance with the surface water quality standard for turbidity(S8.C.2.a) 'Permittees subject to a numeric effluent limit for turbidity may, at their discretion, choose either numeric effluent limitation based on site-specific considerations including, but not limited to, safety, access and convenience. D. Discharges to Water Bodies on the 303(d) List for High pH 1. Permittees who discharge to segments of water bodies on the 303(d) list (Category 5) for high pH must conduct pH sampling in accordance with the table below, and comply with the numeric effluent limit of pH 6.5 to 8.5 su(Table 6). Construction Stormwater General Permit Page 25 Table 6: pH Sampling and Limits for 303(d)-Listed Waters Parameter identified in Parameter Analytical Sampling Numeric Effluent 303(d) listing Sampled/Units Method Frequency Limit High pH pH /Standard pH meter Weekly, if In the range of 6.5 Units discharging —8.5 2. At the Permittee's discretion, compliance with the limit shall be assessed at one of the following locations: a. Directly in the 303(d)-listed waterbody segment, inside the immediate area of influence of the discharge; or b. Alternatively, the Permittee may measure pH at the point where the discharge leaves the construction site, rather than in the receiving water. 3. Discharges that exceed the numeric effluent limit for pH (outside the range of 6.5 — 8.5 su) constitute a violation of this permit. 4. Permittees whose discharges exceed the numeric effluent limit shall sample discharges daily until the violation is corrected and comply with the non- compliance notification requirements in Special Condition S5.F. E. Sampling and Limits for Sites Discharging to Waters Covered by a TMDL or Another Pollution Control Plan 1. Discharges to a waterbody that is subject to a Total Maximum Daily Load (TMDL) for turbidity, fine sediment, high pH, or phosphorus must be consistent with the TMDL. Refer to hqp://www.ecy.wa.gov/programs/wq/tmdl/ TMDLsbyWria/TMDLbyWria.html for more information on TMDLs. a. Where an applicable TMDL sets specific waste load allocations or requirements for discharges covered by this permit, discharges must be consistent with any specific waste load allocations or requirements established by the applicable TMDL. i. The Permittee must sample discharges weekly or as otherwise specified by the TMDL to evaluate compliance with the specific waste load allocations or requirements. ii. Analytical methods used to meet the monitoring requirements must conform to the latest revision of the Guidelines Establishing Test Procedures for the Analysis of Pollutants contained in 40 CFR Part 136. Turbidity and pH methods need not be accredited or registered unless conducted at a laboratory which must otherwise be accredited or registered. b. Where an applicable TMDL has established a general waste load allocation for construction stormwater discharges,but has not identified specific requirements, Construction Stormwater General Permit Page 26 compliance with Special Conditions S4 (Monitoring) and S9 (SWPPPs) will constitute compliance with the approved TMDL. c. Where an applicable TMDL has not specified a waste load allocation for construction stormwater discharges,but has not excluded these discharges, compliance with Special Conditions S4 (Monitoring) and S9 (SWPPPs) will constitute compliance with the approved TMDL. d. Where an applicable TMDL specifically precludes or prohibits discharges from construction activity, the operator is not eligible for coverage under this permit. 2. Applicable TMDL means a TMDL for turbidity, fine sediment, high pH, or phosphorus that is completed and approved by EPA before January 1, 2016, or before the date the operator's complete permit application is received by Ecology, whichever is later. TMDLs completed after the operator's complete permit application is received by Ecology become applicable to the Permittee only if they are imposed through an administrative order by Ecology, or through a modification of permit coverage. S9. STORMWATER POLLUTION PREVENTION PLAN The Permittee must prepare and properly implement an adequate Stormwater Pollution Prevention Plan(SWPPP) for construction activity in accordance with the requirements of this permit beginning with initial soil disturbance and until final stabilization. A. The Permittee's SWPPP must meet the following objectives: 1. To implement best management practices (BMPs)to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. To prevent violations of surface water quality, ground water quality, or sediment management standards. 3. To control peak volumetric flow rates and velocities of stormwater discharges. B. General Requirements 1. The SWPPP must include a narrative and drawings. All BMPs must be clearly referenced in the narrative and marked on the drawings. The SWPPP narrative must include documentation to explain and justify the pollution prevention decisions made for the project. Documentation must include: a. Information about existing site conditions (topography, drainage, soils, vegetation, etc.). b. Potential erosion problem areas. c. The 13 elements of a SWPPP in Special Condition S9.13.1-13, including BMPs used to address each element. Construction Stormwater General Permit Page 27 d. Construction phasing/sequence and general BMP implementation schedule. e. The actions to be taken if BMP performance goals are not achieved—for example, a contingency plan for additional treatment and/or storage of stormwater that would violate the water quality standards if discharged. f. Engineering calculations for ponds, treatment systems, and any other designed structures. 2. The Permittee must modify the SWPPP if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is, or would be, ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The Permittee must then: a. Review the SWPPP for compliance with Special Condition S9 and make appropriate revisions within 7 days of the inspection or investigation. b. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible, addressing the problems no later than 10 days from the inspection or investigation. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when an extension is requested by a Permittee within the initial 10-day response period. c. Document BMP implementation and maintenance in the site log book. The Permittee must modify the SWPPP whenever there is a change in design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the State. C. Stormwater Best Management Practices (BMPs) BMPs must be consistent with: 1. Stormwater Management Manual for Western Washington(most current approved edition at the time this permit was issued), for sites west of the crest of the Cascade Mountains; or 2. Stormwater Management Manual for Eastern Washington (most current approved edition at the time this permit was issued), for sites east of the crest of the Cascade Mountains; or 3. Revisions to the manuals listed in Special Condition S9.C.1. &2., or other stormwater management guidance documents or manuals which provide an equivalent level of pollution prevention, that are approved by Ecology and incorporated into this permit in accordance with the permit modification requirements of WAC 173-226-230; or Construction Stormwater General Permit Page 28 4. Documentation in the SWPPP that the BMPs selected provide an equivalent level of pollution prevention, compared to the applicable Stormwater Management Manuals, including: a. The technical basis for the selection of all stormwater BMPs (scientific, technical studies, and/or modeling) that support the performance claims for the BMPs being selected. b. An assessment of how the selected BMP will satisfy AKART requirements and the applicable federal technology-based treatment requirements under 40 CFR part 125.3. D. SWPPP—Narrative Contents and Requirements The Permittee must include each of the 13 elements below in Special Condition S9.D.1-13 in the narrative of the SWPPP and implement them unless site conditions render the element unnecessary and the exemption from that element is clearly justified in the SWPPP. 1. Preserve Vegetation/Mark Clearing Limits a. Before beginning land-disturbing activities, including clearing and grading, clearly mark all clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the construction area. b. Retain the duff layer, native topsoil, and natural vegetation in an undisturbed state to the maximum degree practicable. 2. Establish Construction Access a. Limit construction vehicle access and exit to one route, if possible. b. Stabilize access points with a pad of quarry spalls, crushed rock, or other equivalent BMPs, to minimize tracking sediment onto roads. c. Locate wheel wash or tire baths on site, if the stabilized construction entrance is not effective in preventing tracking sediment onto roads. d. If sediment is tracked off site, clean the affected roadway thoroughly at the end of each day, or more frequently as necessary(for example, during wet weather). Remove sediment from roads by shoveling, sweeping, or pickup and transport of the sediment to a controlled sediment disposal area. e. Conduct street washing only after sediment removal in accordance with Special Condition S9.D.2.d. Control street wash wastewater by pumping back on site or otherwise preventing it from discharging into systems tributary to waters of the State. 3. Control Flow Rates a. Protect properties and waterways downstream of development sites from erosion and the associated discharge of turbid waters due to increases in the Construction Stormwater General Permit Page 29 velocity and peak volumetric flow rate of stormwater runoff from the project site, as required by local plan approval authority. b. Where necessary to comply with Special Condition S9.D.3.a, construct stormwater retention or detention facilities as one of the first steps in grading. Assure that detention facilities function properly before constructing site improvements (for example, impervious surfaces). c. If permanent infiltration ponds are used for flow control during construction, protect these facilities from siltation during the construction phase. 4. Install Sediment Controls The Permittee must design, install and maintain effective erosion controls and sediment controls to minimize the discharge of pollutants. At a minimum, the Permittee must design, install and maintain such controls to: a. Construct sediment control BMPs (sediment ponds, traps, filters, infiltration facilities, etc.) as one of the first steps in grading. These BMPs must be functional before other land disturbing activities take place. b. Minimize sediment discharges from the site. The design, installation and maintenance of erosion and sediment controls must address factors such as the amount, frequency, intensity and duration of precipitation, the nature of resulting stormwater runoff, and soil characteristics, including the range of soil particle sizes expected to be present on the site. c. Direct stormwater runoff from disturbed areas through a sediment pond or other appropriate sediment removal BMP, before the runoff leaves a construction site or before discharge to an infiltration facility. Runoff from fully stabilized areas may be discharged without a sediment removal BMP, but must meet the flow control performance standard of Special Condition S9.D.3.a. d. Locate BMPs intended to trap sediment on site in a manner to avoid interference with the movement of juvenile salmonids attempting to enter off-channel areas or drainages. e. Provide and maintain natural buffers around surface waters, direct stormwater to vegetated areas to increase sediment removal and maximize stormwater infiltration, unless infeasible. f. Where feasible, design outlet structures that withdraw impounded stormwater from the surface to avoid discharging sediment that is still suspended lower in the water column. 5. Stabilize Soils a. The Permittee must stabilize exposed and unworked soils by application of effective BMPs that prevent erosion. Applicable BMPs include, but are not limited to: temporary and permanent seeding, sodding, mulching, plastic covering, erosion control fabrics and matting, soil application of polyacrylamide Construction Stormwater General Permit Page 30 (PAM), the early application of gravel base on areas to be paved, and dust control. b. The Permittee must control stormwater volume and velocity within the site to minimize soil erosion. c. The Permittee must control stormwater discharges, including both peak flow rates and total stormwater volume, to minimize erosion at outlets and to minimize downstream channel and stream bank erosion. d. Depending on the geographic location of the project, the Permittee must not allow soils to remain exposed and unworked for more than the time periods set forth below to prevent erosion: West of the Cascade Mountains Crest During the dry season (May 1 - September 30): 7 days During the wet season(October 1 - April 30): 2 days East of the Cascade Mountains Crest, except for Central Basin* During the dry season (July 1 - September 30): 10 days During the wet season(October 1 - June 30): 5 days The Central Basin*, East of the Cascade Mountains Crest During the dry season(July 1 - September 30): 30 days During the wet season(October 1 - June 30): 15 days *Note: The Central Basin is defined as the portions of Eastern Washington with mean annual precipitation of less than 12 inches. e. The Permittee must stabilize soils at the end of the shift before a holiday or weekend if needed based on the weather forecast. f. The Permittee must stabilize soil stockpiles from erosion,protected with sediment trapping measures, and where possible, be located away from storm drain inlets,waterways, and drainage channels. g. The Permittee must minimize the amount of soil exposed during construction activity. h. The Permittee must minimize the disturbance of steep slopes. i. The Permittee must minimize soil compaction and, unless infeasible, preserve topsoil. 6. Protect Slopes a. The Permittee must design and construct cut-and-fill slopes in a manner to minimize erosion. Applicable practices include, but are not limited to, reducing continuous length of slope with terracing and diversions, reducing slope steepness, and roughening slope surfaces (for example, track walking). Construction Stormwater General Permit Page 31 b. The Permittee must divert off-site stormwater(run-on) or ground water away from slopes and disturbed areas with interceptor dikes,pipes, and/or swales. Off-site stormwater should be managed separately from stormwater generated on the site. c. At the top of slopes, collect drainage in pipe slope drains or protected channels to prevent erosion. i. West of the Cascade Mountains Crest: Temporary pipe slope drains must handle the peak 10-minute flow rate from a Type IA, 10-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, 1-hour flow rate predicted by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydrologic analysis must use the existing land cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis must use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the Western Washington Hydrology Model (WWHM) to predict flows, bare soil areas should be modeled as "landscaped area." ii. East of the Cascade Mountains Crest: Temporary pipe slope drains must handle the expected peak flow rate from a 6-month, 3-hour storm for the developed condition, referred to as the short duration storm. d. Place excavated material on the uphill side of trenches, consistent with safety and space considerations. e. Place check dams at regular intervals within constructed channels that are cut down a slope. 7. Protect Drain Inlets a. Protect all storm drain inlets made operable during construction so that stormwater runoff does not enter the conveyance system without first being filtered or treated to remove sediment. b. Clean or remove and replace inlet protection devices when sediment has filled one-third of the available storage (unless a different standard is specified by the product manufacturer). 8. Stabilize Channels and Outlets a. Design, construct and stabilize all on-site conveyance channels to prevent erosion from the following expected peak flows: i. West of the Cascade Mountains Crest: Channels must handle the peak 10-minute flow rate from a Type IA, 10-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, 1-hour flow rate indicated by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydrologic analysis must use the existing land Construction Stormwater General Permit Page 32 cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis must use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the WWHM to predict flows, bare soil areas should be modeled as "landscaped area." ii. East of the Cascade Mountains Crest: Channels must handle the expected peak flow rate from a 6-month, 3-hour storm for the developed condition, referred to as the short duration storm. b. Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches at the outlets of all conveyance systems. 9. Control Pollutants Design, install, implement and maintain effective pollution prevention measures to minimize the discharge of pollutants. The Permittee must: a. Handle and dispose of all pollutants, including waste materials and demolition debris that occur on site in a manner that does not cause contamination of stormwater. b. Provide cover, containment, and protection from vandalism for all chemicals, liquid products,petroleum products, and other materials that have the potential to pose a threat to human health or the environment. On-site fueling tanks must include secondary containment. Secondary containment means placing tanks or containers within an impervious structure capable of containing 110% of the volume contained in the largest tank within the containment structure. Double- walled tanks do not require additional secondary containment. c. Conduct maintenance, fueling, and repair of heavy equipment and vehicles using spill prevention and control measures. Clean contaminated surfaces immediately following any spill incident. d. Discharge wheel wash or tire bath wastewater to a separate on-site treatment system that prevents discharge to surface water, such as closed-loop recirculation or upland land application, or to the sanitary sewer with local sewer district approval. e. Apply fertilizers and pesticides in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Follow manufacturers' label requirements for application rates and procedures. f. Use BMPs to prevent contamination of stormwater runoff by pH-modifying sources. The sources for this contamination include,but are not limited to: bulk cement, cement kiln dust, fly ash, new concrete washing and curing waters, recycled concrete stockpiles, waste streams generated from concrete grinding and sawing, exposed aggregate processes, dewatering concrete vaults, concrete Construction Stormwater General Permit Page 33 pumping and mixer washout waters. (Also refer to the definition for "concrete wastewater" in Appendix A--Definitions.) g. Adjust the pH of stormwater or authorized non-stormwater if necessary to prevent an exceedance of groundwater and/or surface water quality standards. h. Assure that washout of concrete trucks is performed off-site or in designated concrete washout areas only. Do not wash out concrete trucks or concrete handling equipment onto the ground, or into storm drains, open ditches, streets, or streams. Do not dump excess concrete on site, except in designated concrete washout areas. Concrete spillage or concrete discharge to surface waters of the State is prohibited. i. Obtain written approval from Ecology before using any chemical treatment, with the exception of CO2 or dry ice used to adjust pH. j. Uncontaminated water from water-only based shaft drilling for construction of building, road, and bridge foundations may be infiltrated provided the wastewater is managed in a way that prohibits discharge to surface waters. Prior to infiltration, water from water-only based shaft drilling that comes into contact with curing concrete must be neutralized until pH is in the range of 6.5 to 8.5 (su). 10. Control Dewatering a. Permittees must discharge foundation, vault, and trench dewatering water, which have characteristics similar to stormwater runoff at the site, into a controlled conveyance system before discharge to a sediment trap or sediment pond. b. Permittees may discharge clean, non-turbid dewatering water, such as well- point ground water, to systems tributary to, or directly into surface waters of the State, as specified in Special Condition S9.D.8,provided the dewatering flow does not cause erosion or flooding of receiving waters. Do not route clean dewatering water through stormwater sediment ponds. Note that"surface waters of the State"may exist on a construction site as well as off site; for example, a creek running through a site. c. Other dewatering treatment or disposal options may include: i. Infiltration. ii. Transport off site in a vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute state waters. iii. Ecology-approved on-site chemical treatment or other suitable treatment technologies (see S9.D.9.i. regarding chemical treatment written approval). iv. Sanitary or combined sewer discharge with local sewer district approval, if there is no other option. Construction Stormwater General Permit Page 34 V. Use of a sedimentation bag with discharge to a ditch or swale for small volumes of localized dewatering. d. Permittees must handle highly turbid or contaminated dewatering water separately from stormwater. 11. Maintain BMPs a. Permittees must maintain and repair all temporary and permanent erosion and sediment control BMPs as needed to assure continued performance of their intended function in accordance with BMP specifications. b. Permittees must remove all temporary erosion and sediment control BMPs within 30 days after achieving final site stabilization or after the temporary BMPs are no longer needed. 12. Manage the Project a. Phase development projects to the maximum degree practicable and take into account seasonal work limitations. b. Inspection and monitoring—Inspect, maintain and repair all BMPs as needed to assure continued performance of their intended function. Conduct site inspections and monitoring in accordance with Special Condition S4. c. Maintaining an updated construction SWPPP—Maintain, update, and implement the SWPPP in accordance with Special Conditions S3, S4 and S9. 13. Protect Low Impact Development(LID) BMPs The primary purpose of LID BMPs/On-site LID Stormwater Management BMPs is to reduce the disruption of the natural site hydrology. LID BMPs are permanent facilities. a. Permittees must protect all Bioretention and Rain Garden facilities from sedimentation through installation and maintenance of erosion and sediment control BMPs on portions of the site that drain into the Bioretention and/or Rain Garden facilities. Restore the facilities to their fully functioning condition if they accumulate sediment during construction. Restoring the facility must include removal of sediment and any sediment-laden Bioretention/Rain Garden soils, and replacing the removed soils with soils meeting the design specification. b. Permittees must maintain the infiltration capabilities of Bioretention and Rain Garden facilities by protecting against compaction by construction equipment and foot traffic. Protect completed lawn and landscaped areas from compaction due to construction equipment. c. Permittees must control erosion and avoid introducing sediment from surrounding land uses onto permeable pavements. Do not allow muddy Construction Stormwater General Permit Page 35 construction equipment on the base material or pavement. Do not allow sediment-laden runoff onto permeable pavements. d. Permittees must clean permeable pavements fouled with sediments or no longer passing an initial infiltration test using local stormwater manual methodology or the manufacturer's procedures. e. Permittees must keep all heavy equipment off existing soils under LID facilities that have been excavated to final grade to retain the infiltration rate of the soils. E. SWPPP—Map Contents and Requirements The Permittee's SWPPP must also include a vicinity map or general location map (for example, a USGS quadrangle map, a portion of a county or city map, or other appropriate map)with enough detail to identify the location of the construction site and receiving waters within one mile of the site. The SWPPP must also include a legible site map (or maps) showing the entire construction site. The following features must be identified,unless not applicable due to site conditions: 1. The direction of north, property lines, and existing structures and roads. 2. Cut and fill slopes indicating the top and bottom of slope catch lines. 3. Approximate slopes, contours, and direction of stormwater flow before and after major grading activities. 4. Areas of soil disturbance and areas that will not be disturbed. 5. Locations of structural and nonstructural controls (BMPs) identified in the SWPPP. 6. Locations of off-site material, stockpiles, waste storage,borrow areas, and vehicle/equipment storage areas. 7. Locations of all surface water bodies, including wetlands. 8. Locations where stormwater or non-stormwater discharges off-site and/or to a surface waterbody, including wetlands. 9. Location of water quality sampling station(s), if sampling is required by state or local permitting authority. 10. Areas where final stabilization has been accomplished and no further construction- phase permit requirements apply. 11. Location or proposed location of LID facilities. Construction Stormwater General Permit Page 36 510. NOTICE OF TERMINATION A. The site is eligible for termination of coverage when it has met any of the following conditions: 1. The site has undergone final stabilization, the Permittee has removed all temporary BMPs (except biodegradable BMPs clearly manufactured with the intention for the material to be left in place and not interfere with maintenance or land use), and all stormwater discharges associated with construction activity have been eliminated; or 2. All portions of the site that have not undergone final stabilization per Special Condition S 10.A.1 have been sold and/or transferred(per General Condition G9), and the Permittee no longer has operational control of the construction activity; or 3. For residential construction only, the Permittee has completed temporary stabilization and the homeowners have taken possession of the residences. B. When the site is eligible for termination, the Permittee must submit a complete and accurate Notice of Termination (NOT) form, signed in accordance with General Condition G2, to: Department of Ecology Water Quality Program—Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 When an electronic termination form is available, the Permittee may choose to submit a complete and accurate Notice of Termination (NOT) form through the Water Quality Permitting Portal rather than mailing a hardcopy as noted above. The termination is effective on the thirty-first calendar day following the date Ecology receives a complete NOT form,unless Ecology notifies the Permittee that the termination request is denied because the Permittee has not met the eligibility requirements in Special Condition S 1 O.A. Permittees are required to comply with all conditions and effluent limitations in the permit until the permit has been terminated. Permittees transferring the property to a new property owner or operator/Permittee are required to complete and submit the Notice of Transfer form to Ecology,but are not required to submit a Notice of Termination form for this type of transaction. Construction Stormwater General Permit Page 37 GENERAL CONDITIONS G1. DISCHARGE VIOLATIONS All discharges and activities authorized by this general permit must be consistent with the terms and conditions of this general permit. Any discharge of any pollutant more frequent than or at a level in excess of that identified and authorized by the general permit must constitute a violation of the terms and conditions of this permit. G2. SIGNATORY REQUIREMENTS A. All permit applications must bear a certification of correctness to be signed: I. In the case of corporations,by a responsible corporate officer; 2. In the case of a partnership, by a general partner of a partnership; 3. In the case of sole proprietorship,by the proprietor; or 4. In the case of a municipal, state, or other public facility, by either a principal executive officer or ranking elected official. B. All reports required by this permit and other information requested by Ecology (including NOIs,NOTs, and Transfer of Coverage forms) must be signed by a person described above or by a duly authorized representative of that person. A person is a duly authorized representative only if- 1. The authorization is made in writing by a person described above and submitted to Ecology. 2. The authorization specifies either an individual or a position having responsibility for the overall operation of the regulated facility, such as the position of plant manager, superintendent, position of equivalent responsibility, or an individual or position having overall responsibility for environmental matters. C. Changes to authorization. If an authorization under paragraph G2.B.2 above is no longer accurate because a different individual or position has responsibility for the overall operation of the facility, a new authorization satisfying the requirements of paragraph G2.13.2 above must be submitted to Ecology prior to or together with any reports, information, or applications to be signed by an authorized representative. D. Certification. Any person signing a document under this section must make the following certification: "I certify under penalty of law, that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gathered and evaluated the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering information, the information submitted is, to the best of my Construction Stormwater General Permit Page 38 knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations." G3. RIGHT OF INSPECTION AND ENTRY The Permittee must allow an authorized representative of Ecology,upon the presentation of credentials and such other documents as may be required by law: A. To enter upon the premises where a discharge is located or where any records are kept under the terms and conditions of this permit. B. To have access to and copy—at reasonable times and at reasonable cost—any records required to be kept under the terms and conditions of this permit. C. To inspect—at reasonable times—any facilities, equipment (including monitoring and control equipment), practices, methods, or operations regulated or required under this permit. D. To sample or monitor—at reasonable times—any substances or parameters at any location for purposes of assuring permit compliance or as otherwise authorized by the Clean Water Act. G4. GENERAL PERMIT MODIFICATION AND REVOCATION This permit may be modified, revoked and reissued, or terminated in accordance with the provisions of Chapter 173-226 WAC. Grounds for modification, revocation and reissuance, or termination include,but are not limited to, the following: A. When a change occurs in the technology or practices for control or abatement of pollutants applicable to the category of dischargers covered under this permit. B. When effluent limitation guidelines or standards are promulgated pursuant to the CWA or Chapter 90.48 RCW, for the category of dischargers covered under this permit. C. When a water quality management plan containing requirements applicable to the category of dischargers covered under this permit is approved, or D. When information is obtained that indicates cumulative effects on the environment from dischargers covered under this permit are unacceptable. G5. REVOCATION OF COVERAGE UNDER THE PERMIT Pursuant to Chapter 43.21B RCW and Chapter 173-226 WAC,the Director may terminate coverage for any discharger under this permit for cause. Cases where coverage may be terminated include, but are not limited to, the following: A. Violation of any term or condition of this permit. B. Obtaining coverage under this permit by misrepresentation or failure to disclose fully all relevant facts. Construction Stormwater General Permit Page 39 C. A change in any condition that requires either a temporary or permanent reduction or elimination of the permitted discharge. D. Failure or refusal of the Permittee to allow entry as required in RCW 90.48.090. E. A determination that the permitted activity endangers human health or the environment, or contributes to water quality standards violations. F. Nonpayment of permit fees or penalties assessed pursuant to RCW 90.48.465 and Chapter 173-224 WAC. G. Failure of the Permittee to satisfy the public notice requirements of WAC 173-226- 130(5), when applicable. The Director may require any discharger under this permit to apply for and obtain coverage under an individual permit or another more specific general permit. Permittees who have their coverage revoked for cause according to WAC 173-226-240 may request temporary coverage under this permit during the time an individual permit is being developed, provided the request is made within ninety(90) days from the time of revocation and is submitted along with a complete individual permit application form. G6. REPORTING A CAUSE FOR MODIFICATION The Permittee must submit a new application, or a supplement to the previous application, whenever a material change to the construction activity or in the quantity or type of discharge is anticipated which is not specifically authorized by this permit. This application must be submitted at least sixty(60) days prior to any proposed changes. Filing a request for a permit modification, revocation and reissuance, or termination, or a notification of planned changes or anticipated noncompliance does not relieve the Permittee of the duty to comply with the existing permit until it is modified or reissued. G7. COMPLIANCE WITH OTHER LAWS AND STATUTES Nothing in this permit will be construed as excusing the Permittee from compliance with any applicable federal, state, or local statutes, ordinances, or regulations. G8. DUTY TO REAPPLY The Permittee must apply for permit renewal at least 180 days prior to the specified expiration date of this permit. The Permittee must reapply using the electronic application form(NOI) available on Ecology's website. Permittees unable to submit electronically(for example, those who do not have an internet connection) must contact Ecology to request a waiver and obtain instructions on how to obtain a paper NOI. Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 Construction Stormwater General Permit Page 40 G9. TRANSFER OF GENERAL PERMIT COVERAGE Coverage under this general permit is automatically transferred to a new discharger, including operators of lots/parcels within a common plan of development or sale, if: A. A written agreement(Transfer of Coverage Form) between the current discharger (Permittee) and new discharger, signed by both parties and containing a specific date for transfer of permit responsibility, coverage, and liability(including any Administrative Orders associated with the Permit) is submitted to the Director; and B. The Director does not notify the current discharger and new discharger of the Director's intent to revoke coverage under the general permit. If this notice is not given, the transfer is effective on the date specified in the written agreement. When a current discharger(Permittee)transfers a portion of a permitted site, the current discharger must also submit an updated application form(NOI) to the Director indicating the remaining permitted acreage after the transfer. G10. REMOVED SUBSTANCES The Permittee must not re-suspend or reintroduce collected screenings, grit, solids, sludges, filter backwash, or other pollutants removed in the course of treatment or control of stormwater to the final effluent stream for discharge to state waters. G11. DUTY TO PROVIDE INFORMATION The Permittee must submit to Ecology, within a reasonable time, all information that Ecology may request to determine whether cause exists for modifying, revoking and reissuing, or terminating this permit or to determine compliance with this permit. The Permittee must also submit to Ecology,upon request, copies of records required to be kept by this permit [40 CFR 122.41(h)]. G12. OTHER REQUIREMENTS OF 40 CFR All other requirements of 40 CFR 122.41 and 122.42 are incorporated in this permit by reference. G13. ADDITIONAL MONITORING Ecology may establish specific monitoring requirements in addition to those contained in this permit by administrative order or permit modification. G14. PENALTIES FOR VIOLATING PERMIT CONDITIONS Any person who is found guilty of willfully violating the terms and conditions of this permit shall be deemed guilty of a crime, and upon conviction thereof shall be punished by a fine of up to ten thousand dollars ($10,000) and costs of prosecution, or by imprisonment at the discretion of the court. Each day upon which a willful violation occurs may be deemed a separate and additional violation. Construction Stormwater General Permit Page 41 Any person who violates the terms and conditions of a waste discharge permit shall incur, in addition to any other penalty as provided by law, a civil penalty in the amount of up to ten thousand dollars ($10,000) for every such violation. Each and every such violation shall be a separate and distinct offense, and in case of a continuing violation, every day's continuance shall be deemed to be a separate and distinct violation. G15. UPSET Definition—"Upset"means an exceptional incident in which there is unintentional and temporary noncompliance with technology-based permit effluent limitations because of factors beyond the reasonable control of the Permittee. An upset does not include noncompliance to the extent caused by operational error, improperly designed treatment facilities, inadequate treatment facilities, lack of preventive maintenance, or careless or improper operation. An upset constitutes an affirmative defense to an action brought for noncompliance with such technology-based permit effluent limitations if the requirements of the following paragraph are met. A Permittee who wishes to establish the affirmative defense of upset must demonstrate, through properly signed, contemporaneous operating logs or other relevant evidence that: 1) an upset occurred and that the Permittee can identify the cause(s) of the upset; 2)the permitted facility was being properly operated at the time of the upset; 3) the Permittee submitted notice of the upset as required in Special Condition SS.F, and; 4) the Permittee complied with any remedial measures required under this permit. In any enforcement proceeding, the Permittee seeking to establish the occurrence of an upset has the burden of proof. G16. PROPERTY RIGHTS This permit does not convey any property rights of any sort, or any exclusive privilege. G17. DUTY TO COMPLY The Permittee must comply with all conditions of this permit. Any permit noncompliance constitutes a violation of the Clean Water Act and is grounds for enforcement action; for permit termination, revocation and reissuance, or modification; or denial of a permit renewal application. G18. TOXIC POLLUTANTS The Permittee must comply with effluent standards or prohibitions established under Section 307(a) of the Clean Water Act for toxic pollutants within the time provided in the regulations that establish those standards or prohibitions, even if this permit has not yet been modified to incorporate the requirement. Construction Stormwater General Permit Page 42 G19. PENALTIES FOR TAMPERING The Clean Water Act provides that any person who falsifies, tampers with, or knowingly renders inaccurate any monitoring device or method required to be maintained under this permit shall, upon conviction, be punished by a fine of not more than $10,000 per violation, or by imprisonment for not more than two years per violation, or by both. If a conviction of a person is for a violation committed after a first conviction of such person under this condition,punishment shall be a fine of not more than$20,000 per day of violation, or imprisonment of not more than four(4) years, or both. G20. REPORTING PLANNED CHANGES The Permittee must, as soon as possible, give notice to Ecology of planned physical alterations, modifications or additions to the permitted construction activity. The Permittee should be aware that, depending on the nature and size of the changes to the original permit, a new public notice and other permit process requirements may be required. Changes in activities that require reporting to Ecology include those that will result in: A. The permitted facility being determined to be a new source pursuant to 40 CFR 122.29(b). B. A significant change in the nature or an increase in quantity of pollutants discharged, including but not limited to: for sites 5 acres or larger, a 20% or greater increase in acreage disturbed by construction activity. C. A change in or addition of surface water(s)receiving stormwater or non-stormwater from the construction activity. D. A change in the construction plans and/or activity that affects the Permittee's monitoring requirements in Special Condition S4. Following such notice,permit coverage may be modified, or revoked and reissued pursuant to 40 CFR 122.62(a) to specify and limit any pollutants not previously limited. Until such modification is effective, any new or increased discharge in excess of permit limits or not specifically authorized by this permit constitutes a violation. G21. REPORTING OTHER INFORMATION Where the Permittee becomes aware that it failed to submit any relevant facts in a permit application, or submitted incorrect information in a permit application or in any report to Ecology, it must promptly submit such facts or information. G22. REPORTING ANTICIPATED NON-COMPLIANCE The Permittee must give advance notice to Ecology by submission of a new application or supplement thereto at least forty-five (45) days prior to commencement of such discharges, of any facility expansions, production increases, or other planned changes, such as process modifications, in the permitted facility or activity which may result in noncompliance with permit limits or conditions. Any maintenance of facilities, which might necessitate Construction Stormwater General Permit Page 43 unavoidable interruption of operation and degradation of effluent quality, must be scheduled during non-critical water quality periods and carried out in a manner approved by Ecology. G23. REQUESTS TO BE EXCLUDED FROM COVERAGE UNDER THE PERMIT Any discharger authorized by this permit may request to be excluded from coverage under the general permit by applying for an individual permit. The discharger must submit to the Director an application as described in WAC 173-220-040 or WAC 173-216-070, whichever is applicable, with reasons supporting the request. These reasons will fully document how an individual permit will apply to the applicant in a way that the general permit cannot. Ecology may make specific requests for information to support the request. The Director will either issue an individual permit or deny the request with a statement explaining the reason for the denial. When an individual permit is issued to a discharger otherwise subject to the construction stormwater general permit, the applicability of the construction stormwater general permit to that Permittee is automatically terminated on the effective date of the individual permit. G24. APPEALS A. The terms and conditions of this general permit, as they apply to the appropriate class of dischargers, are subject to appeal by any person within 30 days of issuance of this general permit, in accordance with Chapter 43.21B RCW, and Chapter 173-226 WAC. B. The terms and conditions of this general permit, as they apply to an individual discharger, are appealable in accordance with Chapter 43.2113 RCW within 30 days of the effective date of coverage of that discharger. Consideration of an appeal of general permit coverage of an individual discharger is limited to the general permit's applicability or nonapplicability to that individual discharger. C. The appeal of general permit coverage of an individual discharger does not affect any other dischargers covered under this general permit. If the terms and conditions of this general permit are found to be inapplicable to any individual discharger(s), the matter shall be remanded to Ecology for consideration of issuance of an individual permit or permits. G25. SEVERABILITY The provisions of this permit are severable, and if any provision of this permit, or application of any provision of this permit to any circumstance, is held invalid, the application of such provision to other circumstances, and the remainder of this permit shall not be affected thereby. G26. BYPASS PROHIBITED A. Bypass Procedures Bypass, which is the intentional diversion of waste streams from any portion of a treatment facility, is prohibited for stormwater events below the design criteria for Construction Stormwater General Permit Page 44 stormwater management. Ecology may take enforcement action against a Permittee for bypass unless one of the following circumstances (1, 2, 3 or 4) is applicable. 1. Bypass of stormwater is consistent with the design criteria and part of an approved management practice in the applicable stormwater management manual. 2. Bypass for essential maintenance without the potential to cause violation of permit limits or conditions. Bypass is authorized if it is for essential maintenance and does not have the potential to cause violations of limitations or other conditions of this permit, or adversely impact public health. 3. Bypass of stormwater is unavoidable,unanticipated, and results in noncompliance of this permit. This bypass is permitted only if: a. Bypass is unavoidable to prevent loss of life, personal injury, or severe property damage. "Severe property damage"means substantial physical damage to property, damage to the treatment facilities which would cause them to become inoperable, or substantial and permanent loss of natural resources which can reasonably be expected to occur in the absence of a bypass. b. There are no feasible alternatives to the bypass, such as the use of auxiliary treatment facilities, retention of untreated wastes, maintenance during normal periods of equipment downtime (but not if adequate backup equipment should have been installed in the exercise of reasonable engineering judgment to prevent a bypass which occurred during normal periods of equipment downtime or preventative maintenance), or transport of untreated wastes to another treatment facility. c. Ecology is properly notified of the bypass as required in Special Condition S5.F of this permit. 4. A planned action that would cause bypass of stormwater and has the potential to result in noncompliance of this permit during a storm event. The Permittee must notify Ecology at least thirty(30) days before the planned date of bypass. The notice must contain: a. A description of the bypass and its cause. b. An analysis of all known alternatives which would eliminate,reduce, or mitigate the need for bypassing. c. A cost-effectiveness analysis of alternatives including comparative resource damage assessment. d. The minimum and maximum duration of bypass under each alternative. e. A recommendation as to the preferred alternative for conducting the bypass. Construction Stormwater General Permit Page 45 f. The projected date of bypass initiation. g. A statement of compliance with SEPA. h. A request for modification of water quality standards as provided for in WAC 173-201A-110, if an exceedance of any water quality standard is anticipated. i. Steps taken or planned to reduce, eliminate, and prevent reoccurrence of the bypass. 5. For probable construction bypasses, the need to bypass is to be identified as early in the planning process as possible. The analysis required above must be considered during preparation of the Stormwater Pollution Prevention Plan (SWPPP) and must be included to the extent practical. In cases where the probable need to bypass is determined early, continued analysis is necessary up to and including the construction period in an effort to minimize or eliminate the bypass. Ecology will consider the following before issuing an administrative order for this type bypass: a. If the bypass is necessary to perform construction or maintenance-related activities essential to meet the requirements of this permit. b. If there are feasible alternatives to bypass, such as the use of auxiliary treatment facilities, retention of untreated wastes, stopping production, maintenance during normal periods of equipment down time, or transport of untreated wastes to another treatment facility. c. If the bypass is planned and scheduled to minimize adverse effects on the public and the environment. After consideration of the above and the adverse effects of the proposed bypass and any other relevant factors, Ecology will approve, conditionally approve, or deny the request. The public must be notified and given an opportunity to comment on bypass incidents of significant duration, to the extent feasible. Approval of a request to bypass will be by administrative order issued by Ecology under RCW 90.48.120. B. Duty to Mitigate The Permittee is required to take all reasonable steps to minimize or prevent any discharge or sludge use or disposal in violation of this permit that has a reasonable likelihood of adversely affecting human health or the environment. Construction Stormwater General Permit Page 46 APPENDIX A—DEFINITIONS AKART is an acronym for"all known, available, and reasonable methods of prevention, control, and treatment."AKART represents the most current methodology that can be reasonably required for preventing, controlling, or abating the pollutants and controlling pollution associated with a discharge. Applicable TMDL means a TMDL for turbidity, fine sediment, high pH, or phosphorus,which was completed and approved by EPA before January 1, 2016, or before the date the operator's complete permit application is received by Ecology, whichever is later. Applicant means an operator seeking coverage under this permit. Benchmark means a pollutant concentration used as a permit threshold,below which a pollutant is considered unlikely to cause a water quality violation, and above which it may. When pollutant concentrations exceed benchmarks, corrective action requirements take effect. Benchmark values are not water quality standards and are not numeric effluent limitations; they are indicator values. Best Management Practices (BMPs) means schedules of activities,prohibitions of practices, maintenance procedures, and other physical, structural and/or managerial practices to prevent or reduce the pollution of waters of the State. BMPs include treatment systems, operating procedures, and practices to control: stormwater associated with construction activity, spillage or leaks, sludge or waste disposal, or drainage from raw material storage. Buffer means an area designated by a local jurisdiction that is contiguous to and intended to protect a sensitive area. Bypass means the intentional diversion of waste streams from any portion of a treatment facility. Calendar Day A period of 24 consecutive hours starting at 12:00 midnight and ending the following 12:00 midnight. Calendar Week(same as Week) means a period of seven consecutive days starting at 12:01 a.m. (0:01 hours) on Sunday. Certified Erosion and Sediment Control Lead (CESCL) means a person who has current certification through an approved erosion and sediment control training program that meets the minimum training standards established by Ecology(see BMP C160 in the SWMM). Chemical Treatment means the addition of chemicals to stormwater and/or authorized non- stormwater prior to filtration and discharge to surface waters. Clean Water Act(CWA) means the Federal Water Pollution Control Act enacted by Public Law 92-500, as amended by Public Laws 95-217, 95-576, 96-483, and 97-117; USC 1251 et seq. Combined Sewer means a sewer which has been designed to serve as a sanitary sewer and a storm sewer, and into which inflow is allowed by local ordinance. Construction Stormwater General Permit Page 47 Common Plan of Development or Sale means a site where multiple separate and distinct construction activities may be taking place at different times on different schedules and/or by different contractors, but still under a single plan. Examples include: 1)phased projects and projects with multiple filings or lots, even if the separate phases or filings/lots will be constructed under separate contract or by separate owners (e.g., a development where lots are sold to separate builders); 2) a development plan that may be phased over multiple years, but is still under a consistent plan for long-term development; 3)projects in a contiguous area that may be unrelated but still under the same contract, such as construction of a building extension and a new parking lot at the same facility; and 4) linear projects such as roads, pipelines, or utilities. If the project is part of a common plan of development or sale, the disturbed area of the entire plan must be used in determining permit requirements. Composite Sample means a mixture of grab samples collected at the same sampling point at different times, formed either by continuous sampling or by mixing discrete samples. May be "time-composite" (collected at constant time intervals) or "flow-proportional" (collected either as a constant sample volume at time intervals proportional to stream flow, or collected by increasing the volume of each aliquot as the flow increases while maintaining a constant time interval between the aliquots. Concrete Wastewater means any water used in the production,pouring and/or clean-up of concrete or concrete products, and any water used to cut, grind, wash, or otherwise modify concrete or concrete products. Examples include water used for or resulting from concrete truck/mixer/pumper/tool/chute rinsing or washing, concrete saw cutting and surfacing(sawing, coring, grinding, roughening, hydro-demolition,bridge and road surfacing). When stormwater comingles with concrete wastewater, the resulting water is considered concrete wastewater and must be managed to prevent discharge to waters of the State, including ground water. Construction Activity means land disturbing operations including clearing, grading or excavation which disturbs the surface of the land. Such activities may include road construction, construction of residential houses, office buildings, or industrial buildings, site preparation, soil compaction, movement and stockpiling of topsoils, and demolition activity. Contaminant means any hazardous substance that does not occur naturally or occurs at greater than natural background levels. See definition of"hazardous substance" and WAC 173-340-200. Contaminated Groundwater means groundwater which contains contaminants,pollutants, or hazardous substances that do not occur naturally or occur at levels greater than natural background. Contaminated Soil means soil which contains contaminants,pollutants, or hazardous substances that do not occur naturally or occur at levels greater than natural background. Demonstrably Equivalent means that the technical basis for the selection of all stormwater BMPs is documented within a SWPPP, including: 1. The method and reasons for choosing the stormwater BMPs selected. Construction Stormwater General Permit Page 48 2. The pollutant removal performance expected from the BMPs selected. 3. The technical basis supporting the performance claims for the BMPs selected, including any available data concerning field performance of the BMPs selected. 4. An assessment of how the selected BMPs will comply with state water quality standards. 5. An assessment of how the selected BMPs will satisfy both applicable federal technology- based treatment requirements and state requirements to use all known, available, and reasonable methods of prevention, control, and treatment(AKART). Department means the Washington State Department of Ecology. Detention means the temporary storage of stormwater to improve quality and/or to reduce the mass flow rate of discharge. Dewatering means the act of pumping ground water or stormwater away from an active construction site. Director means the Director of the Washington State Department of Ecology or his/her authorized representative. Discharger means an owner or operator of any facility or activity subject to regulation under Chapter 90.48 RCW or the Federal Clean Water Act. Domestic Wastewater means water carrying human wastes, including kitchen, bath, and laundry wastes from residences, buildings, industrial establishments, or other places, together with such ground water infiltration or surface waters as may be present. Ecology means the Washington State Department of Ecology. Engineered Soils means the use of soil amendments including, but not limited, to Portland cement treated base (CTB), cement kiln dust (CKD), or fly ash to achieve certain desirable soil characteristics. Equivalent BMPs means operational, source control, treatment, or innovative BMPs which result in equal or better quality of stormwater discharge to surface water or to ground water than BMPs selected from the SWMM. Erosion means the wearing away of the land surface by running water, wind, ice, or other geological agents, including such processes as gravitational creep. Erosion and Sediment Control BMPs means BMPs intended to prevent erosion and sedimentation, such as preserving natural vegetation, seeding, mulching and matting,plastic covering, filter fences, sediment traps, and ponds. Erosion and sediment control BMPs are synonymous with stabilization and structural BMPs. Federal Operator is an entity that meets the definition of"Operator" in this permit and is either any department, agency or instrumentality of the executive, legislative, and judicial branches of Construction Stormwater General Permit Page 49 the Federal government of the United States, or another entity, such as a private contractor, performing construction activity for any such department, agency, or instrumentality. Final Stabilization (same as fully stabilized or full stabilization)means the establishment of a permanent vegetative cover, or equivalent permanent stabilization measures (examples of permanent non-vegetative stabilization methods include,but are not limited to riprap, gabions or geotextiles) which prevents erosion. Ground Water means water in a saturated zone or stratum beneath the land surface or a surface waterbody. Hazardous Substance means any dangerous or extremely hazardous waste as defined in RCW 70.105.010(5)and(6),or any dangerous or extremely dangerous waste as designated by rule under chapter 70.105 RCW; any hazardous substance as defined in RCW 70.105.010(10) or any hazardous substance as defined by rule under chapter 70.105 RCW; any substance that, on the effective date of this section,is a hazardous substance under section 101(14)of the federal cleanup law,42 U.S.C., Sec. 9601(14);petroleum or petroleum products; and any substance or category of substances, including solid waste decomposition products, determined by the director by rule to present a threat to human health or the environment if released into the environment. The term hazardous substance does not include any of the following when contained in an underground storage tank from which there is not a release: crude oil or any fraction thereof or petroleum, if the tank is in compliance with all applicable federal, state, and local law. Injection Well means a well that is used for the subsurface emplacement of fluids. (See Well.) Jurisdiction means a political unit such as a city, town or county; incorporated for local self- government. National Pollutant Discharge Elimination System (NPDES)means the national program for issuing, modifying, revoking and reissuing,terminating, monitoring, and enforcing permits, and imposing and enforcing pretreatment requirements, under sections 307, 402, 318, and 405 of the Federal Clean Water Act, for the discharge of pollutants to surface waters of the State from point sources. These permits are referred to as NPDES permits and, in Washington State, are administered by the Washington State Department of Ecology. Notice of Intent (NOI) means the application for, or a request for coverage under this general permit pursuant to WAC 173-226-200. Notice of Termination (NOT)means a request for termination of coverage under this general permit as specified by Special Condition S 10 of this permit. Operator means any party associated with a construction project that meets either of the following two criteria: • The party has operational control over construction plans and specifications, including the ability to make modifications to those plans and specifications; or Construction Stormwater General Permit Page 50 • The party has day-to-day operational control of those activities at a project that are necessary to ensure compliance with a SWPPP for the site or other permit conditions (e.g., they are authorized to direct workers at a site to carry out activities required by the SWPPP or comply with other permit conditions). Permittee means individual or entity that receives notice of coverage under this general permit. pH means a liquid's measure of acidity or alkalinity. A pH of 7 is defined as neutral. Large variations above or below this value are considered harmful to most aquatic life. pH Monitoring Period means the time period in which the pH of stormwater runoff from a site must be tested a minimum of once every seven days to determine if stormwater pH is between 6.5 and 8.5. Point Source means any discernible, confined, and discrete conveyance, including but not limited to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, and container from which pollutants are or may be discharged to surface waters of the State. This term does not include return flows from irrigated agriculture. (See Fact Sheet for further explanation.) Pollutant means dredged spoil, solid waste, incinerator residue, filter backwash, sewage, garbage, domestic sewage sludge (biosolids), munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt, and industrial, municipal, and agricultural waste. This term does not include sewage from vessels within the meaning of section 312 of the CWA, nor does it include dredged or fill material discharged in accordance with a permit issued under section 404 of the CWA. Pollution means contamination or other alteration of the physical, chemical, or biological properties of waters of the State; including change in temperature, taste, color, turbidity, or odor of the waters; or such discharge of any liquid, gaseous, solid, radioactive or other substance into any waters of the State as will or is likely to create a nuisance or render such waters harmful, detrimental or injurious to the public health, safety or welfare; or to domestic, commercial, industrial, agricultural, recreational, or other legitimate beneficial uses; or to livestock, wild animals, birds, fish or other aquatic life. Process Wastewater means any water which, during manufacturing or processing, comes into direct contact with or results from the production or use of any raw material, intermediate product, finished product,byproduct, or waste product. If stormwater commingles with process wastewater, the commingled water is considered process wastewater. Receiving Water means the waterbody at the point of discharge. If the discharge is to a storm sewer system, either surface or subsurface, the receiving water is the waterbody to which the storm system discharges. Systems designed primarily for other purposes such as for ground water drainage, redirecting stream natural flows, or for conveyance of irrigation water/return flows that coincidentally convey stormwater are considered the receiving water. Construction Stormwater General Permit Page 51 Representative means a stormwater or wastewater sample which represents the flow and characteristics of the discharge. Representative samples may be a grab sample, a time- proportionate composite sample, or a flow proportionate sample. Ecology's Construction Stormwater Monitoring Manual provides guidance on representative sampling. Responsible Corporate Officer for the purpose of signatory authority means: (i) a president, secretary, treasurer, or vice-president of the corporation in charge of a principal business function, or any other person who performs similar policy- or decision-making functions for the corporation, or(ii) the manager of one or more manufacturing, production, or operating facilities, provided, the manager is authorized to make management decisions which govern the operation of the regulated facility including having the explicit or implicit duty of making major capital investment recommendations, and initiating and directing other comprehensive measures to assure long term environmental compliance with environmental laws and regulations; the manager can ensure that the necessary systems are established or actions taken to gather complete and accurate information for permit application requirements; and where authority to sign documents has been assigned or delegated to the manager in accordance with corporate procedures (40 CFR 122.22). Sanitary Sewer means a sewer which is designed to convey domestic wastewater. Sediment means the fragmented material that originates from the weathering and erosion of rocks or unconsolidated deposits, and is transported by, suspended in, or deposited by water. Sedimentation means the depositing or formation of sediment. Sensitive Area means a waterbody, wetland, stream, aquifer recharge area, or channel migration zone. SEPA(State Environmental Policy Act) means the Washington State Law, RCW 43.21C.020, intended to prevent or eliminate damage to the environment. Significant Amount means an amount of a pollutant in a discharge that is amenable to available and reasonable methods of prevention or treatment; or an amount of a pollutant that has a reasonable potential to cause a violation of surface or ground water quality or sediment management standards. Significant Concrete Work means greater than 1000 cubic yards poured concrete used over the life of a project. Significant Contributor of Pollutants means a facility determined by Ecology to be a contributor of a significant amount(s) of a pollutant(s) to waters of the State of Washington. Site means the land or water area where any "facility or activity" is physically located or conducted. Source Control BMPs means physical, structural or mechanical devices or facilities that are intended to prevent pollutants from entering stormwater. A few examples of source control Construction Stormwater General Permit Page 52 BMPs are erosion control practices, maintenance of stormwater facilities, constructing roofs over storage and working areas, and directing wash water and similar discharges to the sanitary sewer or a dead end sump. Stabilization means the application of appropriate BMPs to prevent the erosion of soils, such as, temporary and permanent seeding, vegetative covers, mulching and matting,plastic covering and sodding. See also the definition of Erosion and Sediment Control BMPs. Storm Drain means any drain which drains directly into a storm sewer system, usually found along roadways or in parking lots. Storm Sewer System means a means a conveyance, or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains designed or used for collecting or conveying stormwater. This does not include systems which are part of a combined sewer or Publicly Owned Treatment Works (POTW) as defined at 40 CFR 122.2. Stormwater means that portion of precipitation that does not naturally percolate into the ground or evaporate, but flows via overland flow, interflow, pipes, and other features of a stormwater drainage system into a defined surface waterbody, or a constructed infiltration facility. Stormwater Management Manual(SWMM) or Manual means the technical Manual published by Ecology for use by local governments that contain descriptions of and design criteria for BMPs to prevent, control, or treat pollutants in stormwater. Stormwater Pollution Prevention Plan (SWPPP) means a documented plan to implement measures to identify,prevent, and control the contamination of point source discharges of stormwater. Surface Waters of the State includes lakes, rivers, ponds, streams, inland waters, salt waters, and all other surface waters and water courses within the jurisdiction of the State of Washington. Temporary Stabilization means the exposed ground surface has been covered with appropriate materials to provide temporary stabilization of the surface from water or wind erosion. Materials include, but are not limited to, mulch, riprap, erosion control mats or blankets and temporary cover crops. Seeding alone is not considered stabilization. Temporary stabilization is not a substitute for the more permanent"final stabilization." Total Maximum Daily Load (TMDL) means a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet state water quality standards. Percentages of the total maximum daily load are allocated to the various pollutant sources. A TMDL is the sum of the allowable loads of a single pollutant from all contributing point and nonpoint sources. The TMDL calculations must include a "margin of safety" to ensure that the waterbody can be protected in case there are unforeseen events or unknown sources of the pollutant. The calculation must also account for seasonable variation in water quality. Construction Stormwater General Permit Page 53 Transfer of Coverage (TOC)means a request for transfer of coverage under this general permit as specified by General Condition G9 of this permit. Treatment BMPs means BMPs that are intended to remove pollutants from stormwater. A few examples of treatment BMPs are detention ponds, oil/water separators, biofiltration, and constructed wetlands. Transparency means a measurement of water clarity in centimeters (cm), using a 60 cm transparency tube. The transparency tube is used to estimate the relative clarity or transparency of water by noting the depth at which a black and white Secchi disc becomes visible when water is released from a value in the bottom of the tube. A transparency tube is sometimes referred to as a"turbidity tube." Turbidity means the clarity of water expressed as nephelometric turbidity units (NTUs) and measured with a calibrated turbidimeter. Uncontaminated means free from any contaminant. See definition of"contaminant" and WAC 173-340-200. Waste Load Allocation (WLA) means the portion of a receiving water's loading capacity that is allocated to one of its existing or future point sources of pollution. WLAs constitute a type of water quality based effluent limitation (40 CFR 130.2[h]). Water-only Based Shaft Drilling is a shaft drilling process that uses water only and no additives are involved in the drilling of shafts for construction of building, road, or bridge foundations. Water quality means the chemical,physical, and biological characteristics of water,usually with respect to its suitability for a particular purpose. Waters of the State includes those waters as defined as "waters of the United States" in 40 CFR Subpart 122.2 within the geographic boundaries of Washington State and "waters of the State" as defined in Chapter 90.48 RCW, which include lakes, rivers,ponds, streams, inland waters, underground waters, salt waters, and all other surface waters and water courses within the jurisdiction of the state of Washington. Well means a bored, drilled or driven shaft, or dug hole whose depth is greater than the largest surface dimension. (See Injection well.) Wheel Wash Wastewater means any water used in, or resulting from the operation of, a tire bath or wheel wash(BMP C 106: Wheel Wash), or other structure or practice that uses water to physically remove mud and debris from vehicles leaving a construction site and prevent track- out onto roads. When stormwater comingles with wheel wash wastewater, the resulting water is considered wheel wash wastewater and must be managed according to Special Condition S9.D.9. Construction Stormwater General Permit Page 54 APPENDIX B—ACRONYMS AKART All Known, Available, and Reasonable Methods of Prevention, Control, and Treatment BMP Best Management Practice CESCL Certified Erosion and Sediment Control Lead CFR Code of Federal Regulations CKD Cement Kiln Dust CM Centimeters CTB Cement-Treated Base CWA Clean Water Act DMR Discharge Monitoring Report EPA Environmental Protection Agency ERTS Environmental Report Tracking System ESC Erosion and Sediment Control FR Federal Register LID Low Impact Development NOI Notice of Intent NOT Notice of Termination NPDES National Pollutant Discharge Elimination System NTU Nephelometric Turbidity Unit RCW Revised Code of Washington SEPA State Environmental Policy Act SWMM Stormwater Management Manual SWPPP Stormwater Pollution Prevention Plan TMDL Total Maximum Daily Load UIC Underground Injection Control USC United States Code USEPA United States Environmental Protection Agency WAC Washington Administrative Code WQ Water Quality WWHM Western Washington Hydrology Model Construction Stormwater General Permit Page 55 Stormwater Pollution Prevention Plan Appendix E — Site Inspection Forms (and Site Log) The results of each inspection shall be summarized in an inspection report or checklist that is entered into or attached to the site log book. It is suggested that the inspection report or checklist be included in this appendix to keep monitoring and inspection information in one document,but this is optional. However, it is mandatory that this SWPPP and the site inspection forms be kept onsite at all times during construction, and that inspections be performed and documented as outlined below. At a minimum, each inspection report or checklist shall include: a. Inspection date/times b. Weather information: general conditions during inspection, approximate amount of precipitation since the last inspection, and approximate amount of precipitation within the last 24 hours. C. A summary or list of all BMPs that have been implemented, including observations of all erosion/sediment control structures or practices. d. The following shall be noted: i. locations of BMPs inspected, ii. locations of BMPs that need maintenance, iii. the reason maintenance is needed, iv. locations of BMPs that failed to operate as designed or intended, and v. locations where additional or different BMPs are needed, and the reason(s)why e. A description of stormwater discharged from the site. The presence of suspended sediment, turbid water, discoloration, and/or oil sheen shall be noted, as applicable. f. A description of any water quality monitoring performed during inspection, and the results of that monitoring. g. General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. h. A statement that, in the judgment of the person conducting the site inspection, the site is either in compliance or out of compliance with the terms and conditions of the SWPPP and the NPDES permit. If the site inspection indicates that the site is out of compliance, the inspection report shall include a summary of the remedial actions required to bring the site back into compliance, as well as a schedule of implementation. 28 Stormwater Pollution Prevention Plan i. Name, title, and signature of person conducting the site inspection; and the following statement: "I certify under penalty of law that this report is true, accurate, and complete, to the best of my knowledge and belief'. When the site inspection indicates that the site is not in compliance with any terms and conditions of the NPDES permit, the Permittee shall take immediate action(s)to: stop, contain, and clean up the unauthorized discharges, or otherwise stop the noncompliance; correct the problem(s); implement appropriate Best Management Practices (BMPs), and/or conduct maintenance of existing BMPs; and achieve compliance with all applicable standards and permit conditions. In addition, if the noncompliance causes a threat to human health or the environment, the Permittee shall comply with the Noncompliance Notification requirements in Special Condition S5.F of the permit. 29 Stormwater Pollution Prevention Plan Site Inspection Form General Information Project Name: Inspector Name: Title: CESCL # : Date: Time: Inspection Type: ❑ After a rain event ❑ Weekly ❑ Turbidity/transparency benchmark exceedance ❑ Other Weather Precipitation Since last inspection In last 24 hours Description of General Site Conditions: Inspection of BMPs Element 1: Mark Clearing Limits BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FY N NIP Element 2: Establish Construction Access BMP: Inspected Functioning Location Y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning problem/Corrective Action Y N FYFN NIP LLI 29 Stormwater Pollution Prevention Plan Element 3: Control Flow Rates BMP: Location Inspected Functioning problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 4: Install Sediment Controls BMP: Inspected Functioning Location y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP 30 Stormwater Pollution Prevention Plan Element S: Stabilize Soils BMP: Location Inspected Functioning problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning problem/Corrective Action Y N FY N1 NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 6: Protect Slopes BMP: Inspected Functioning Location y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP 31 Stormwater Pollution Prevention Plan Element 7: Protect Drain Inlets BMP: Location Inspected Functioning problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning problem/Corrective Action Y N FY N1 NIP Element 8: Stabilize Channels and Outlets BMP: Inspected Functioning Location y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning Problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP 32 Stormwater Pollution Prevention Plan Element 9: Control Pollutants BMP: Inspected Functioning Location y N Y N NIP Problem/Corrective Action BMP: Inspected Functioning Location y N Y N NIP Problem/Corrective Action Element 10: Control Dewatering BMP: Inspected Functioning Location y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FY N NIP 33 Stormwater Pollution Prevention Plan Stormwater Discharges From the Site Observed? Problem/Corrective Action YFN Location Turbidity Discoloration Sheen Location Turbidity Discoloration Sheen 34 Stormwater Pollution Prevention Plan Water Quality Monitoring Was any water quality monitoring conducted? ❑ Yes ❑ No If water quality monitoring was conducted, record results here: If water quality monitoring indicated turbidity 250 NTU or greater; or transparency 6 cm or less, was Ecology notified by phone within 24 hrs? ❑ Yes ❑ No If Ecology was notified, indicate the date,time, contact name and phone number below: Date: Time: Contact Name: Phone #: General Comments and Notes Include BMP repairs, maintenance, or installations made as a result of the inspection. Were Photos Taken? ❑ Yes ❑ No If photos taken, describe photos below: 35 CONTRUCTION PLAN REVIEW & INSPECTION FEE WORKSHEET Community& Economic Development Department City of Arlington . 18204 59th Avenue NE . Arlington WA 98223 . (360)403-3551 This form is to be completed and submitted with Tvpe I , Tvpe 11 Type III Construction Permit Application. 1) Based on permit type requested (Type I,Type II or Type III), complete the form as follows: . Type I permits complete all sections. . Type II permits complete as follows: - Grading Only-Complete Temporary Erosion and Sediment Control (TESC). - Stormwater Drainage Only-Complete the Temporary Erosion and Sediment Control and Stormwater Drainage Section for Public or Private . Type III permits complete the Temporary Erosion and Sediment Control (TESC). 2) The developer shall enter the quantities shown on the construction drawings into the Construction Calculation Worksheet. This document is used to determine the amount of plan reivew and inspection fees due to the city. 3) Excel will auto-calculate the relevant fields and subtotals throughout the document. Only the'Quantity'columns should be completed. 4) The summary page calculates the fees due at intake for Civil and Stormwater Drainage construction permits only. This does not include fees for Grading or those required by other departments or agencies. Grading fees are based on Cubic Yard Quantity and shall be calculated at time of permit submittal. Grading fees shall be paid at permit submittal. 5) If an item that is part of your project does not exist in the spreadsheet complete the Write-In-Items section with the item, quantity and associated unit cost. There are a few unit prices that are blank, please complete them accordingly. 6) Inspection fees shall be calculated for Private Development during the review process and shall be paid upon permit issuance. PROJECT COSTS PUBLIC TOTAL PRIVATE TOTAL TOTAL PROJECT COST $ 6,858.75 $ 157,162.50 1 $ 164,021.25 Verify formula, totals do not match PLAN REVIEW& INSPECTION FEES PLAN REVIEW&INSPECTION FEE (6%of Project Value) $ 9,841.28 GRADING FEE(4) (Cubic Yard ) $ - Review fees due at time of submittal Total Review Fees Due $ 9,841.28 An Assurance Device such as a Performance Bond or Assignment of Funds needs to be on file with the City of Arlington prior to permit issuance. The Assurance Device shall be 150%of the Construction Calculation Worksheet which are as follows: Road and Alley (Public) Stormwater Drainage and Grading (Public) Utilities (Public) Temporary Erosion and Sediment Control (Public and Private) ASSURANCE DEVICE Base Calculation of Performance Device $ 6,858.75 PERFORMANCE DEVICE 150% Amount Due $ 10,288.13 Base Calculation of Maintenance Device $ 6,250.00 MAINTENANCE DEVICE 20% Amount Due $ 1,250.00 1 Rev 7/2017 GEOTECHNICAL ENGINEERING REPORT EAST ARLINGTON SUBSTATION SITE IMPROVEMENTS 21210 - 8711 Avenue NE Arlington, Washington Project No. 1643.01 B 15 September 2016 Prepared for: Snohomish County PUD No. 1 LL 1' 'of � z Y 7 -ate Prepared by: ZGA Zipper Geo Associates, LLC Geotechnical and Environmental Consultants 19023 36t" Avenue W., Suite D Lynnwood, WA 98036 Zipper Geo Associates, LLC Geotechnical and Environmental Consulting Project No. 1643.01E 15 September 2016 Snohomish County PUD No. 1 Distribution & Engineering Services Division PO Box 1107 Everett, Washington 98206-1107 Attention: Mr.Tom Hendricks, PE Professional Engineer Subject: Geotechnical Engineering Report East Arlington Substation Site Improvements 21210—871h Avenue NE Arlington, Washington Dear Mr. Hendricks: In accordance with your request and written authorization, Zipper Geo Associates, LLC (ZGA) has completed the subsurface exploration and geotechnical engineering evaluation for the proposed East Arlington Substation Site Improvements. This report presents the findings of the subsurface exploration and geotechnical recommendations for the project. Our work was completed in general accordance with the scope of services described in Contract No. CW2225339. Written authorization to proceed was provided by the District on 26 May 2016. We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report,or if we may be of further assistance,please contact us. Sincerely, o as � Zipper Geo Associates LLC �te )��9�0 �tiRT A. / .y 40 of W't �JcP . .Bering Geologsl �. David C. Williams, LG, LEG C� 1172 �`� Robert A. Ross, PE �O 'P�r 38384 Principal Engineering Geologist G0 Principal �S810 DAVID C. WILLIAMS Distribution: Addressee (1 electronic, 1 hard copy) 19023 361h Avenue West, Suite D Lynnwood, WA 98036 (425) 582-9928 TABLE OF CONTENTS INTRODUCTION .....................................................................................................................1 PROJECT INFORMATION.........................................................................................................1 Site Location and Description .............................................................................................1 ProjectDescription.............................................................................................................1 SITE CONDITIONS...................................................................................................................2 SurfaceConditions.............................................................................................................2 Subsurface Conditions........................................................................................................2 Groundwater.....................................................................................................................3 CONCLUSIONSAND................................................................................................................4 RECOMMENDATIONS.............................................................................................................4 Geotechnical Considerations ..............................................................................................4 Geologically Hazardous Areas.............................................................................................4 Earthwork..........................................................................................................................6 SitePreparation.................................................................................................................6 Structural Fill Placement and Compaction...........................................................................7 Utility Installation Recommendations.................................................................................9 Below-grade Vault Recommendations..............................................................................11 Shallow Foundation Design Recommendations.................................................................12 Shallow Foundation Construction Considerations..............................................................12 Seismic Design Parameters...............................................................................................13 Drilled Pier Foundation/Direct Burial Recommendations.................................................13 Open Shaft Construction Considerations...........................................................................19 IBC Non-constrained Pole Design Recommendations.........................................................20 Concrete Slab Subgrade Preparation Recommendations ...................................................21 Stormwater Infiltration Considerations.............................................................................21 ErosionControl ................................................................................................................23 CLOSURE..............................................................................................................................24 FIGURES Figure 1—Site and Exploration Plan APPENDICES Appendix A—Subsurface Exploration Procedures and Logs Appendix B—Boring Logs by Others Appendix C—Laboratory Testing Procedures and Results GEOTECHNICAL ENGINEERING REPORT EAST ARLINGTON SUBSTATION SITE IMPROVEMENTS 21210—87T"AVENUE NE ARLINGTON, WASHINGTON Project No. 1643.01B 15 September 2016 INTRODUCTION The geotechnical engineering exploration and analysis have been completed for the proposed East Arlington Substation Site Improvements project in Arlington, Washington. Two exploratory borings (B-7, B-8) were completed to depths ranging from approximately 7.5 to 15 feet below the existing ground surface to evaluate subsurface conditions. In addition, we considered subsurface conditions as described on the logs of four borings (B-1-90 through B-4-90) advanced by Dames & Moore in January 1991 as part of a previous geotechnical evaluation of the site. Descriptive logs of the ZGA explorations are included in Appendix A and logs of the Dames& Moore borings are included in Appendix B. PROJECT INFORMATION Site Location and Description The project site is located at 21210—87th Avenue NE in Arlington,Washington.The site,which is an active substation, is roughly rectangular and has rough dimensions of 175 feet (north-south) by 265 feet (east- west). The substation is bordered to the east by 871h Avenue NE, to the west by a transmission line easement, to the north by a US Navy switch yard, and to the south by Tveit Road. The project site is illustrated on the Site and Exploration Plan, Figure 1. Project Description The project consists of replacing the existing substation components with new ones. Site improvements are expected to include: • Dead end towers; • Circuit breakers, disconnect switches, neutral reactors, and bus supports; • A slab-supported control enclosure at the east; • Below-grade conduits and pre-cast concrete vaults; • A stormwater infiltration system consisting of a perforated pipe and washed rock-filled trenches along with catch basins; Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 • The finished grade is expected to remain essentially the same as the existing grade. SITE CONDITIONS Surface Conditions The site and adjacent areas are largely level. The ground surface elevation in the main yard is at or near 160 feet, and there is a small hump at elevation 162 feet near the northwest corner. With the exception of the northwest corner,the entire yard is surfaced with coarse gravel-size crushed rock. Surfacing in the northwest corner consists of gravelly sand and quarry spalls. We did not observe standing or flowing surface water in the yard or immediately adjacent areas during our site visits. Subsurface Conditions The publication Geologic Map of the Arlington East Quadrangle, Snohomish County, Washington (US Geological Survey Map MF-1739, dated 1985) describes the site as underlain by the Marysville Sand member of recessional outwash deposits. However, based upon the conditions disclosed by borings completed on the site, it appears that the native soils are more representative of the glacial till which has been mapped to the southeast and northwest of the site and underlies the recessional deposits. Specifically, we have interpreted that much of the native soil is consistent with ablation till which was formed during retreat of the last glacial ice mass that covered western Washington. Some granular recessional outwash was also observed above the ablation till. The developed nature of the site suggests that fill material is present as well. The subsurface exploration program completed for this study included advancing two hollow stem auger borings(B-7 and B-8)at the approximate exploration locations shown on Figure 1. Figure 1 also illustrates the approximate locations of four borings (B-1-90 through B-4-90) advanced by Dames& Moore in 1991. Details of the field exploration program completed for this study, along with the logs of borings B-7 and B-8,are presented in Appendix A. Logs of the Dames&Moore borings are included in Appendix B. Details of the geotechnical laboratory testing program and the results of the laboratory tests are presented in Appendix C and on the logs in Appendix A as appropriate. The soil descriptions presented below have been generalized for ease of report interpretation. Please refer to the exploration logs for detailed soil descriptions at the exploration locations. Variations in subsurface conditions may exist between the exploration locations and the nature and extent of variations between the explorations may not become evident until construction. If variations then appear, it may be necessary to reevaluate the recommendations of this report. Subsurface conditions as disclosed by the borings are summarized below. Fill material consisting of a few inches of coarse gravel size crushed rock mantled most of the yard; only a relatively small area in the vicinity of boring B-8 lacked this surfacing. Probable fill material consisting of Page 2 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 medium dense to very dense gravelly sand was observed to boring B-7's termination depth of 7.5 feet. Drilling action suggested the presence of coarse gravel and/or cobbles at this location. Approximately 2 feet of loose to medium dense sandy gravel with some quarry spalls (fill) was observed at the location of boring B-8. Dames&Moore reported about 3 inches and 2 feet of medium dense silty gravel (base course fill) at the locations of borings B-1-90 an B-2-90, respectively. Dames & Moore also observed approximately 5 feet of loose silty fine sand with wood fragments interpreted as fill at the boring B-4-90 location. It should be noted that the composition and depth of fill material may vary over relatively short distances. Native soils observed below surficial fill material generally consisted of medium dense to very dense silty sand with a variable gravel content. A 2-foot thick horizon of hard silt was observed immediately below the fill at the location of boring B-8. Visual observation and laboratory testing indicated that the soils were moist to wet at the time of drilling. Groundwater Groundwater was not observed while advancing borings B-7 and B-8. Dames&Moore reported observing groundwater at depths ranging from approximately 6 to 13 feet while advancing their borings in January 1991. Groundwater conditions should be expected to fluctuate due to changes in seasonal precipitation, site utilization, and other factors. Subsurface conditions observed at the locations of borings B-1 and B-8, as well as conditions described in the Dames & Moore report, are summarized in the table below. Table 1: Subsurface Conditions Summary Exploration Approx. Ground Surface Approx. Fill Thickness (feet) Approx. Groundwater* Elev. (feet) Depth/ Elevation (feet) B-7 160 7.5+ NE B-8 160 2 NE B-1-90 160 2 10/ 150 B-2-90 160 0.25 13/ 147 B-3-90 159 NE 6/153 B-4-90 158 5 13/ 145 Ground surface elevations were derived from topographic survey, dated 11 July 2016, by Harmsen & Associates, Inc. NE: Not encountered at the time of exploration *Groundwater observed at time of drilling Page 3 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 Relative to conditions encountered during construction of the proposed site improvements, the contractor should be aware that excavations are expected to encounter existing foundations which are expected to include drilled piers, augercast piles, and slabs. Conduits and grounding grid should be expected in excavations as well. CONCLUSIONS AND RECOMMENDATIONS Geotechnical Considerations Based on information gathered during the field exploration, laboratory testing, and analysis,we conclude that construction of the proposed improvements is feasible from the geotechnical perspective provided that the recommendations presented herein are followed during design and construction. Selected aspects of the site conditions that should be considered during design and construction are summarized below. • The site is underlain primarily by native soils consisting of at least medium dense granular soil, much of which has a relatively high fines content. Some granular fill material ranging from loose to dense was observed at some of the boring locations. Groundwater was not observed at the locations of borings B-7 and B-8 advanced most recently, and groundwater was observed at depths of approximately 6 to 13 feet in January 1991 at the Dames&Moore boring locations. The soil and groundwater conditions may be considered favorable relative to the proposed site improvements. • The use of both shallow foundations as well as drilled pier foundations typically used for the District's substations may be considered feasible from the geotechnical perspective. • The overall high fines content of the site soils will yield an effective overall relatively low infiltration rate relative to stormwater management. Geotechnical engineering recommendations for site grading, drainage, foundations, and other geotechnically-related aspects of the project are presented in the following sections. The recommendations contained in this report are based upon the results of and the field exploration, laboratory testing, engineering analyses, and our current understanding of the proposed substation design. ASTM and WSDOT specification codes cited herein refer to the current manual published by the American Society for Testing& Materials and the 2010 edition of the WSDOT Standard Specifications for Road, Bridge, and Municipal Construction (Publication M41-10). Geologically Hazardous Areas The City of Arlington regulates geologically hazardous areas via Chapter 20.88 of the Arlington Municipal Code(AMC). Geologically hazardous areas"...include areas susceptible to erosion,sliding,seismic activity, or other geological events.They pose a threat to the health and safety of citizens when used as sites for Page 4 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 incompatible commercial, residential or industrial development". Geologically hazardous areas relative to the project site are discussed below. Erosion Hazard The AMC defines an erosion hazard as a landform or soil type subject to being worn away by the action of water, wind,freeze-thaw or ice. The site is mantled with granular fill material consisting primarily of coarse gravel size crushed rock with secondary gravelly sand and quarry spalls, and the site is level. We did not observe evidence of surface water erosion on or immediately adjacent to the site during our visits. It is our opinion that the use of conventional Temporary Erosion and Sedimentation Control (TESC) measures approved by the City of Arlington during construction will reduce the potential for sediment generation and off-site sediment transport. Erosion control recommendations are presented subsequently in this report. Landslide Hazard The AMC defines a landslide hazard as an area potentially subject to risk of mass movement due to a combination of factors, including historic failures. The site and immediately surrounding area are level, so the risk of landsliding on the site or immediately adjacent to it is negligible. The exploratory borings did not disclose landslide deposits or landslide debris. Based upon our current understanding of site conditions, it is our opinion that the site does not meet the AMC definition of a landslide hazard area. Seismic Hazard Area The AMC defines seismic hazard areas as areas that include areas subject to severe risk of earthquake damage as a result of seismic induced settlement, shaking, slope failure or soil liquefaction. These conditions occur in areas underlain by cohesionless soils of low density usually in association with a shallow groundwater table. Ground Surface Rupture: According to the US Geological Survey on-line fault map database, the site is approximately 8 miles southwest of the Devils Mountain fault. The north-dipping fault zone of the Devils Mountain fault extends westward for more than 75 miles from the Cascade Range foothills to offshore Vancouver Island.At its east end,the Devils Mountain fault intersects or merges with the Darrington fault zone. At its west end, the Devils Mountain fault may merge with the Leech River and/or San Juan faults on Vancouver Island. Quaternary strata are deformed on nearly all seismic-reflection profiles crossing the fault in the eastern Strait of Juan de Fuca,and onshore subsurface data suggest offset of upper Pleistocene strata across the fault. The most recent significant displacement along the fault is thought to have Page 5 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 occurred over 130,000 years ago, and data suggest that the slip rate is less than 0.2 millimeters per year. Based upon the proximity of the site to the referenced mapped fault, it is our opinion that the risk of ground surface rupture is low. The USGS on-line Quaternary fault mapping may be viewed at http://earthquake.usgs.gov/hazards/qfaults/map/. Landsliding: Based on the level topography of the site and surrounding vicinity, the risk of earthquake- induced landsliding is negligible, in our opinion. Soil Liquefaction: Liquefaction is a phenomenon wherein saturated cohesionless soils build up excess pore water pressures during earthquake loading. Liquefaction typically occurs in loose soils, but may occur in denser soils if the ground shaking is sufficiently strong. Based upon the observed overall medium dense to very dense soils disclosed by the borings and the lack of a pervasive shallow groundwater condition, it is our opinion that the risk of liquefaction is negligible. Slopes The AMC also regulates some slopes as follows: • Moderate slopes shall include any slope greater than or equal to fifteen percent and less than thirty-three percent. • Steep slopes shall include any slope greater than or equal to thirty-three percent. The project site is level and does not contain slopes regulated under the AMC. Earthwork The following sections present recommendations for site preparation, subgrade preparation and placement of engineered fills on the project. The recommendations presented in this report for design and construction of foundations and slabs are contingent upon following the recommendations outlined in this section. Earthwork on the project should be observed and evaluated by a ZGA representative. Evaluation of earthwork should include observation and testing of structural fill, subgrade preparation, foundation bearing soils, deep foundations, and subsurface drainage installations. Site Preparation Demolition: Activities completed prior to construction are recommended to include removal of existing foundations,slabs,and conduits that maybe in conflict with proposed improvements. Following removal of existing shallow foundations, slabs, and conduits, we recommend backfilling the excavations with structural fill placed and compacted per the recommendations presented in the Structural Fill section of Page 6 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 this report. We anticipate that drilled piers and augercast piles may be present as well. If it is feasible to remove the drilled piers, the resultant excavations should be backfilled with either compacted structural fill or with Controlled Density Fill (CDF) or lean mix concrete with a minimum 28-day 50 psi compressive strength. If these foundations are only partially removed, we recommend that they be cut off at least 2 feet below the subgrade elevation of new foundations or slab and the space between be backfilled with compacted structural fill, CDF, or lean mix concrete. Stripping: We recommend leaving the existing yard rock in place to serve as an all-weather working surface and the reduce disturbance of the underlying soils by construction equipment. Structural Fill Placement and Compaction We anticipate that the yard grade will be at or very near existing grade following construction,so extensive grading will not be required. Structural fill will be placed for conduit and vault installations,storm drainage piping and structures, and below and adjacent to new foundations and slabs. All fill material should be placed in accordance with the recommendations herein for structural fill. Prior to placement,the surfaces to receive structural fill should be observed by a ZGA representative in order to assess the subgrade adequacy. In the event that soft or loose soils are present at the subgrade elevation, the soils should be compacted to a firm and non-yielding condition prior to placing structural fill. This may require partial removal of existing fill material and replacing it as compacted structural fill. In the event that the soils cannot be adequately compacted, they should be removed as necessary and replaced with compacted granular fill material. The suitability of soils for use as structural fill depends primarily on the gradation and moisture content of the soil when it is placed. As the amount of fines (that soil fraction passing the US No. 200 sieve) increases, soil becomes increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult, or impossible, to achieve. Generally, soils containing more than about 5 percent fines by weight (based on that soil fraction passing the US No. 4 sieve) cannot be compacted to a firm, non-yielding condition when the moisture content is more than a few percent from optimum. The optimum moisture content is that which yields the greatest soil density under a given compactive effort. Re-use of On-site Soils: The fines content of the shallow soils likely to be encountered in excavations for foundations,conduits, and vaults,for example,was quite variable, ranging from about 4 to 36 percent for tested samples. Consequently,the moisture sensitivity of the site soils should be expected to vary across the site, and the feasibility of using on-site soils as structural fill would best be made during construction. If construction is scheduled for the wetter time of year,we suggest that the District consider that it would be difficult, or impossible, to dry wet of optimum soils prior to their use as structural fill. Imported Structural Fill: We recommend that import soils for use as general structural fill material consist of a well-graded sand and gravel with a low fines content, such as the District's standard substation fill, Page 7 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 the gradation of which is presented in the table below. Alternatively, material meeting the gradation criteria for Crushed Surfacing-Base Course per WSDOT 9-03.9(3) may be used as structural fill. Table 2: Snohomish County PUD No. 1 Substation Import Granular Fill Gradation US Standard Sieve Size Percent Passing by Dry Weight Basis 2 inch 100 inch 56- 100 inch 40-78 No. 10 22 -57 No.40 8-32 No. 200 < 5 The use of other fill types should be reviewed and approved by ZGA prior to their use on site. Compaction Recommendations: Structural fill should be placed in horizontal lifts and compacted to a firm and non-yielding condition using equipment and procedures that will produce the recommended moisture content and densities throughout the fill. Fill lifts should generally not exceed 10 inches in loose thickness, although the nature of the compaction equipment in use and its effectiveness will influence functional fill lift thicknesses. Recommended compaction criteria for structural fill materials, including trench backfill, are as follows: Table 3: Recommended Soil Compaction Levels Location Minimum Percent Compaction* All fill below and adjacent to slabs and shallow foundations 95 General fill embankments and utility trench backfill 95 Conduit trench backfill above bedding sand or CDF 95 Landscaping areas 85-90 * ASTM D 1557 Modified Proctor Maximum Dry Density Earthwork may be difficult or impossible during periods of elevated soil moisture and wet weather. If soils are stockpiled for future use and wet weather is anticipated,the stockpile should be protected with plastic sheeting that is securely anchored. Subgrade soils that become disturbed due to elevated moisture conditions should be overexcavated to expose firm, non-yielding, non-organic soils and backfilled with compacted structural fill. We recommend that the earthwork portion of this project be completed during extended periods of dry weather if possible. If earthwork is completed during the wet season (typically November through June) it will be necessary to take extra precautionary measures to protect subgrade soils. Wet season earthwork may require additional mitigative measures beyond that which would be expected during the drier summer Page 8 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 and fall months. This could include diversion of surface runoff around exposed soils and draining of ponded water. Once subgrades are established, it will be necessary to protect the exposed subgrade soils from construction traffic during wet weather. Placing quarry spalls, crushed recycled concrete, or salvaged yard rock over these areas would further protect the soils from construction traffic. If earthwork takes place during freezing conditions, we recommend allowing the exposed subgrade to thaw and then recompacting the subgrade prior to placing subsequent lifts of engineered fill. Frozen soil should not be used as structural fill. We recommend that a ZGA representative be present during the construction phase of the project to observe earthwork operations and to perform necessary tests and observations during subgrade preparation, placement and compaction of structural fill, backfilling of excavations, and prior to construction of foundations and slabs. Drainage: Positive drainage should be provided during construction and maintained throughout the life of the project. Uncontrolled movement of water into trenches or foundation and slab excavations during construction should be prevented. Additional Considerations: It is anticipated that excavations for the proposed improvements can be accomplished with conventional earthmoving equipment. Excavation Quantities: It has been our experience that grading calculations need to accommodate a "shrink or swell" factor when comparing in-place soil volumes to truck volumes. We recommend considering that the in-place volume of soil removed from excavations will increase by approximately 25 to 40 percent when measured on a loose cubic yards basis (truck yards). Likewise, loose truck yards delivered to the site will shrink on the order of 25 to 30 percent when compared to the in-place compacted volume of the soil. Truck yards are also subject to other discrepancies when correlating to bank yards, including "rounding errors"that can be significant. Utility Installation Recommendations Below-grade utilities are expected to include conduits,vaults, and storm sewer piping and structures. We recommend that utility trenching conform to all applicable federal, state, and local regulations, such as OSHA and WISHA,for open excavations. The existing shallow soils are generally expected to be adequate for support of conduits,storm drainage piping, and associated vaults and catch basins, although localized subgrade improvement may be necessary given the potential for localized soft or loose soils at the base of excavations. Some of the site soils may be easily disturbed by excavation and construction equipment, particularly during wet weather,and may need to be compacted prior to utility installation. Subgrade soils that cannot be compacted to a firm and non-yielding condition should be removed and replaced with clean granular Page 9 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 structural fill that can be compacted to the density recommended in the Structural Fill section of this report. All trenches should be wide enough to allow for compaction around the haunches of the pipe. If water is encountered in the excavations, it should be removed prior to fill placement. Materials, placement and compaction of utility trench backfill exclusive of CDF should be in accordance with the recommendations presented in the Structural Fill section of this report. In our opinion, the initial lift thickness should not exceed 1 foot unless recommended by the manufacturer to protect utilities from damage by compacting equipment. Light,hand operated compaction equipment may be utilized directly above utilities if damage resulting from heavier compaction equipment is of concern. Dewatering: Groundwater was not observed while advancing borings B-7 and B-8. Groundwater was observed at depths ranging from approximately 6 to 13 feet at the locations of the four Dames & Moore borings. While it should be recognized that groundwater conditions are likely to vary seasonally, we anticipate that the need for dewatering most excavations for conduits, vaults, the stormwater management system, and shallow foundations will be low. However, depending upon the time of year that the work takes place, perched groundwater may be encountered. The contractor should be prepared to pump water from excavations as necessary to maintain a relatively dry trench condition. Temporary Excavation Slopes: We recommend that utility trenching, installation,and backfilling conform to all applicable Federal, State, and local regulations such as WISHA and OSHA regulations for open excavations. In order to maintain the function of any existing utilities that may be located near excavations,we recommend that temporary excavations not encroach upon the bearing splay of existing utilities,foundations, or slabs. The bearing splay of structures and utilities should be considered to begin at the edge of the utility,foundation,or slab and extend downward at a 1H:1V(Horizontal:Vertical)slope. If, due to space constraints, an open excavation cannot be completed without encroaching on a utility, we recommend shoring the new utility excavation with a slip box or other suitable means that provide for protection of workers and that maintain excavation sidewall integrity to the depth of the excavation. Temporary slope stability is a function of many factors, including the following: • The presence and abundance of groundwater; • The type and density of the various soil strata; • The depth of cut; • Surcharge loadings adjacent to the excavation; Page 10 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 • The length of time the excavation remains open. It is exceedingly difficult under the variable circumstances presented by uncontrolled fill material to pre- establish a safe and "maintenance-free" temporary cut slope angle. Therefore, it should be the responsibility of the contractor to maintain safe slope configurations since the contractor is continuously at the job site, able to observe the nature and condition of the cut slopes, and able to monitor the subsurface materials and groundwater conditions encountered. It may be necessary to drape temporary slopes with plastic or to otherwise protect the slopes from the elements and minimize sloughing and erosion. We do not recommend vertical slopes or cuts deeper than 4 feet if worker access is necessary. The cuts should be adequately sloped or supported to prevent injury to personnel from local sloughing and spalling. The excavation should conform to applicable Federal, State, and local regulations. Based upon our review of WAC 296-155-66401 (Appendix A—Soil Classification),we have interpreted the existing soils disclosed by the explorations to a depth of about 10 feet as meeting the Type C definition. The contractor should be responsible for determining soil types in all excavations and should be prepared to adequately shore or slope all excavations. Please note that some of the granular soils have a low fines content and that unsupported excavation sidewalls in these soils may slough or cave readily. Below-grade Vault Recommendations Bearing Conditions: Below-grade conduit vaults will be installed as part of the project. Based upon our experience with other District facilities, and depending on the orientation of the new conduit sweeps,the vault bases may be up to approximately 6 feet below grade. Based upon conditions disclosed by the explorations, we anticipate that vault subgrades will generally consist of at least medium dense granular soils. Some variation in soil type and density at vault subgrade locations should be expected. The vaults will exert a relatively low bearing pressure. We recommend placing a minimum 6-inch compacted thickness of crushed rock below the vaults as a leveling course. The crushed rock should conform to the quality and gradation requirements for Crushed Surfacing — Base Course per WSDOT Specification 9-03.9(3). Buoyancy Considerations: A seasonal shallow perched groundwater condition may develop above the site-characteristic shallow silt soils, and this may subject the vaults to buoyant forces. Potential buoyant forces acting on the vaults may be calculated by multiplying the volume of the portion of the vault below the water table (in cubic feet) by 62.4 pcf. Buoyant forces maybe resisted by the weight of a vault and its contents. Additional resistance to buoyant forces may be achieved by installing flanges on the vault base. The weight of the soil backfill placed above the flanges will assist in counteracting buoyant forces. We recommend using a soil density of 125 pcf for backfill above the water table, and 60 pcf for backfill below the water table. Page 11 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 Shallow Foundation Design Recommendations It will be feasible to use conventional shallow foundations for new structures bearing upon at least medium dense native soil, existing medium dense fill material lacking debris and more than about 4 percent organics, and new structural fill placed and compacted in accordance with the recommendations presented in this report. Recommended criteria for shallow foundations are summarized below. Net allowable bearing pressure: 3,000 psf for at least medium dense native granular soils or granular structural fill compacted to at least 95 percent of the modified Proctor maximum dry density. This value incorporates a factor of safety of 3. A one-third increase may be applied for short-term wind or seismic loading. Minimum dimensions: 15 inches Minimum embedment for frost protection: 18 inches Estimated total settlement: Less than 1 inch Estimates differential settlement: One half of total settlement Ultimate passive resistance: 425 psf. This value assumes that foundations are backfilled with granular backfill compacted to 95 percent density and does not include a factor of safety. Neglect the upper 18 inches of embedment when calculating passive resistance. Ultimate coefficient of base friction: 0.45 Shallow Foundation Construction Considerations The base of all foundation excavations should be free of water, loose soil, or debris prior to placing concrete, and should be prepared as recommended in this report. Concrete should be placed soon after excavating to reduce bearing soil disturbance. Should the soils at bearing level become excessively dry, disturbed, saturated, or frozen, the affected soil should be removed prior to placing concrete. We recommend placing a 6-inch thick lift of compacted crushed rock above the bearing soils to reduce disturbance of the underlying bearing soils until such time as concrete is poured. It is recommended that a ZGA representative evaluate foundation subgrades prior to placing the crushed rock and prior to form and reinforcing steel placement. If unsuitable bearing soils are encountered in foundation excavations,the excavation should be extended deeper to suitable soils. The foundations could bear directly on suitable soils at the lower level or on lean concrete or CDF backfill placed in the excavations. As an alternative, the foundations could also bear on properly compacted backfill extending down to the suitable soils. Overexcavation for compacted backfill placement below foundations should extend laterally beyond all edges of the foundations a distance of Page 12 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 one foot per foot of overexcavation depth below foundation base elevation. The overexcavation should then be backfilled up to the footing base elevation with imported granular material placed in lifts of 10 inches or less in loose thickness and compacted to at least 95 percent of the material's modified Proctor maximum dry density (ASTM D 1557). If excavations are backfilled with lean mix concrete or CDF, we recommend using material with a minimum compressive strength of 55 psi. In this case, the overexcavation need only be as wide as the foundation. Seismic Design Parameters Table 4: Seismic Design Parameters Category Designation or Value 2012 International Building Code(IBC)1 C Z S,Spectral Acceleration for a Short Period 1.051g,Site Class B S1 Spectral Acceleration for a 1-Second Period 0.408g,Site Class B SM,Spectral Acceleration for a Short Period 1.134g,Site Class C SM,Spectral Acceleration for a 1-Second Period 0.650g,Site Class C 1. In general accordance with the 2012 International Building Code, Table 1613.5.2. 2. The 2012 International Building Code requires a site soil profile determination extending a depth of 100 feet for seismic site classification. The current scope requested did not include the required 100 foot soil profile determination. The borings reviewed as part of our evaluation extended to a maximum depth of approximately 29 feet and this seismic site class definition considers that stiff soils as noted on the published geologic mapping exist below the maximum depth of the subsurface exploration. Additional exploration to greater depths could be considered to confirm the conditions below the current depth of exploration. Drilled Pier Foundation/Direct Burial Recommendations Drilled piers may be used to support the new slabs as an alternative to the recommendations presented above,as well the new dead end structures. In addition,we understand that the dead end structures may be installed via direct burial. Based upon conditions observed at the locations of the exploratory borings advanced for this current evaluation and also by Dames & Moore in 1991, site conditions are favorable for the use of drilled pier foundations or direct burial. We understand that the District will design the foundations in-house. The tables below provide recommended soil values for incorporation into the District's design relative to specific borings. We have not incorporated factors of safety into the listed values. The depth intervals referenced in the tables are relative to the existing ground surface elevation at the specific boring locations. Cohesion values are not provided as the soils are primarily granular. The pressuremeter elastic modulus values are based upon published correlations with Standard Penetration Test values (N) published in "Estimating Foundation Settlements in Residual Soils", Journal of the Page 13 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 Geotechnical Engineering Division, Vol. 103, No. 3, March 1977. The soil wet density values listed do not consider buoyancy effects of soils below groundwater. Table 5A: Recommended Soil Parameters Based on ZGA Boring B-7 Depth interval Soil Condition Averaged Correlated Soil Wet Internal Friction in feet below Standard Pressuremeter Density Angle existing grade Penetration Elastic Modulus (pcf) (0,in degrees) Resistance(N) (kips/in')' 0-2 Med. dense 19 2.5 125 32 gravelly sand (fill) 2—7.5 Dense gravelly 50 3.13 140 41 sand(fill) 1. The pressuremeter modulus values are based upon published correlations between Standard Penetration Test values(N)and the pressuremeter modulus; a factor of safety does not apply. Table 5B: Recommended Soil Parameters Based on ZGA Boring B-7 Depth Soil Condition Relative Ultimate Ultimate Moisture Rankine interval in Density Friction Friction Content Coefficient feet below (Dr aspercent) Factor' Factor (percent by Active/Passive existing dry weight grade basis) 0-2 Med.dense 50 0.55 0.40 7 0.31/3.25(neglect gravelly sand 0-1.5 feet) (fill) 2—7.5 Dense gravelly 85 0.55 0.40 12 0.21/4.81 sand (fill) 1. The ultimate friction factors are based upon published values for adhesion between concrete and the applicable soil type. 2. The ultimate friction factors are based upon published values for adhesion between steel and the applicable soil type. 3. Passive resistance in the upper 1.5 feet should be neglected entirely. Page 14 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 Table 6A: Recommended Soil Parameters Based on ZGA Boring B-8 Depth interval Soil Condition Average Correlated Soil Wet Internal Friction in feet below Standard Elastic Density Angle existing grade Penetration Pressuremeter (pcf) (0,in degrees) Resistance(N) Modulus (kips/in')' 0-2 Loose to med. 22 2.64 125 34 dense sandy gravel with cobbles(fill) 2—3.8 Hard silt 46 4.17 130 40 3.8—9.5 Med. dense 26 2.78 135 35 gravelly silty sand 9.5—15 Med.dense 14 1.53 130 31 gravelly silty sand 1. The pressuremeter modulus values are based upon published correlations between Standard Penetration Test values(N)and the pressuremeter modulus;a factor of safety does not apply. Table 613: Recommended Soil Parameters Based on ZGA Boring B-8 Depth Soil Condition Relative Ultimate Ultimate Moisture Rankine interval in Density Friction Friction Content Coefficient feet below (Dr aspercent) Factor' Factor (percent by Active/Passive' existing dry weight grade basis) 0-2 Loose to med. 55 0.55 0.4 6 0.28/3.54(neglect dense sandy 0—1.5 feet) gravel with cobbles(fill) 2—3.8 Hard silt 80 0.33 0.2 21 0.22/4.6 3.8—9.5 Med. dense 60 0.55 0.4 26 0.273.69 gravelly silty sand 9.5—15 Med. dense 40 0.55 0.4 14 0.32/3.12 gravelly silty sand _ 1. The ultimate friction factors are based upon published values for adhesion between concrete and the applicable soil type. 2. The ultimate friction factors are based upon published values for adhesion between steel and the applicable soil type. 3. Passive resistance in the upper 1.5 feet should be neglected entirely. Page 15 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 Table 7A: Recommended Soil Parameters Based on Dames&Moore Boring B-1-90 Depth interval Soil Condition Average Correlated Soil Wet Internal Friction in feet below Standard Elastic Density Angle existing grade Penetration Pressuremeter (pcf) (0,in degrees) Resistance(N) Modulus (kips/in')' 0—12.5 Med. dense silty 17 2.5 146 32 gravel (fill) above med. dense silty sand 12.5—26.5 Medium dense 28 2.78 142 35 silty sand 1. The pressuremeter modulus values are based upon published correlations between Standard Penetration Test values(N)and the pressuremeter modulus;a factor of safety does not apply. Table 7B: Recommended Soil Parameters Based on Dames&Moore Boring B-1-90 Depth Soil Condition Relative Ultimate Ultimate Moisture Rankine interval in Density Friction Friction Content Coefficient feet below (Dr as percent) Factor' Factor' (percent by Active/Passive' existing dry weight grade basis) 0—12.5 Med.dense 45 0.5 0.3 13 0.31/3.25(neglect silty gravel (fill) 0—1.5 feet) above med. dense silty sand 12.5—26.5 Med.dense 65 0.5 0.3 12 0.27/3.69 silty sand 1. The ultimate friction factors are based upon published values for adhesion between concrete and the applicable soil type. 2. The ultimate friction factors are based upon published values for adhesion between steel and the applicable soil type. 3. Passive resistance in the upper 1.5 feet should be neglected entirely. Page 16 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 Table 8A: Recommended Soil Parameters Based on Dames&Moore Boring B-2-90 Depth interval Soil Condition Average Correlated Soil Wet Internal Friction in feet below Standard Elastic Density Angle existing grade Penetration Pressuremeter (pcf) (0,in degrees) Resistance(N) Modulus (kips/in2)1 0-6 Med. dense sand 48 3.47 140 40 with gravel 6-24 Med.dense to 26 2.78 140 35 dense silty sand 1. The pressuremeter modulus values are based upon published correlations between Standard Penetration Test values(N)and the pressuremeter modulus;a factor of safety does not apply. Table 8B: Recommended Soil Parameters Based on Dames&Moore Boring B-2-90 Depth Soil Condition Relative Ultimate Ultimate Moisture Rankine interval in Density Friction Friction Content Coefficient feet below (Dr aspercent) Factor' Factor (percent by Active/Passive' existing dry weight grade basis) 0-6 Med.dense 83 0.5 0.3 14 0.22/4.6 (neglect silty gravel (fill) 0-1.5 feet) above med. dense silt sand 6-24 Medium dense 60 0.5 0.25 10 0.27/3.69 silty sand 1. The ultimate friction factors are based upon published values for adhesion between concrete and the applicable soil type. 2. The ultimate friction factors are based upon published values for adhesion between steel and the applicable soil type. 3. Passive resistance in the upper 1.5 feet should be neglected entirely. Page 17 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 Table 9A: Recommended Soil Parameters Based on Dames& Moore Boring B-3-90 Depth interval Soil Condition Average Correlated Soil Wet Internal Friction in feet below Standard Elastic Density Angle existing grade Penetration Pressuremeter (pcf) (0,in degrees) Resistance(N) Modulus (kips/in')' 0-6 Loose to med. 15 1.53 130 32 dense sand 6—26.5 Dense to v.dense 42 4.03 143 39 sand,silty sand, and gravel 1. The pressuremeter modulus values are based upon published correlations between Standard Penetration Test values(N)and the pressuremeter modulus;a factor of safety does not apply. Table 9B: Recommended Soil Parameters Based on Dames&Moore Boring B-3-90 Depth Soil Condition Relative Ultimate Ultimate Moisture Rankine interval in Density Friction Friction Content Coefficient feet below (Dr aspercent) Factor' Factor (percent by Active/Passive' existing dry weight grade basis) 0-6 Loose to med. 42 0.5 0.3 6 0.31/3.25(neglect dense sand 0—1.5 feet) 6—26.5 Dense to v. 75 0.5 0.3 11 0.23/4.4 dense sand, silty sand,and gravel 1. The ultimate friction factors are based upon published values for adhesion between concrete and the applicable soil type. 2. The ultimate friction factors are based upon published values for adhesion between steel and the applicable soil type. 3. Passive resistance in the upper 1.5 feet should be neglected entirely. Page 18 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 Table 10A: Recommended Soil Parameters Based on Dames&Moore Boring B-4-90 Depth interval Soil Condition Average Correlated Soil Wet Internal Friction in feet below Standard Elastic Density Angle existing grade Penetration Pressuremeter (pcf) (0,in degrees) Resistance(N) Modulus (kips/in')' 0—7.5 Loose silty sand 4 0.76 110 28 (fill to 5 feet) 7.5—18 Dense silty gravel 73 4.86 121 44 18-29 Med.dense to 24 2.78 125 35 dense silty sand with gravel 1. The pressuremeter modulus values are based upon published correlations between Standard Penetration Test values(N)and the pressuremeter modulus; a factor of safety does not apply. Table 10B: Recommended Soil Parameters Based on Dames&Moore Boring B-4-90 Depth Soil Condition Relative Ultimate Ultimate Moisture Rankine interval in Density Friction Friction Content Coefficient feet below (Dr as percent) Factor' Factor (percent by Active/Passive' existing dry weight grade basis) 0—7.5 Loose silty sand 15 0.5 0.25 5 0.36/2.77(neglect (fill to 5 feet) 0-1.5 feet) 7.5-18 Dense silty 95 0.5 0.3 8 0.18/5.55 gravel 18-29 Med. dense to 55 0.5 0.3 15 0.27/3.69 dense silty sand with gravel 1. The ultimate friction factors are based upon published values for adhesion between concrete and the applicable soil type. 2. The ultimate friction factors are based upon published values for adhesion between steel and the applicable soil type. 3. Passive resistance in the upper 1.5 feet should be neglected entirely. Drilled Pier End Bearing Considerations: When calculating drilled pier end bearing values, it will be necessary to consider the density of the soils to a depth below the shaft that is a function of the shaft diameter. We can provide specific end bearing capacity recommendations once preliminary design efforts for the drilled pier foundations have identified likely drilled pier diameters and depths. Open Shaft Construction Considerations Given the soil conditions encountered at the exploratory boring locations,we anticipate that construction of the shafts can be accomplished with standard drilling equipment. Though not recovered as part of the sampling process,the drilling and sampling process suggested the presence of coarse gravel and cobbles Page 19 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 within the native soils,and boulders may also be present in the native soils as well. The contractor should be prepared to deal with the presence of cobbles and boulders over the drilled depth interval, as well as obstructions within the alluvial deposits, such as logs. We recommend that the contractor be prepared to case drilled boreholes to reduce sidewall sloughing. We recommend that the contractor be required to have on site sufficient material to case the entire drilled depth. We recommend that the drilling contractor have a cleanout bucket on site to remove loose soils from the bottom of the borings. We recommend that the foundation concrete be tremied from the bottom of the hole to displace water and to reduce the risk of contaminating or segregating the concrete mix should any accumulate in the shafts. A minimum 5-foot head of concrete should be maintained above the tremie. The Drilled Shaft Manual published by the Federal Highway Administration recommends that concrete be placed by tremie methods if more than 3 inches of water has accumulated in the excavation. IBC Non-constrained Pole Design Recommendations Section 1805.7.2.1 of the 2003 the International Building Code (IBC) describes the methodology for determining a drilled pier foundation or pole depth of embedment in cases where no constraint is provided at the surface to resist lateral forces. As per your request, we have evaluated the equivalent passive soil pressure per foot of depth for use in the IBC method. Recommended lateral bearing pressures as a function of pole depth are listed below in Table 8. We recommend neglecting resistance in the upper 1.5 feet of embedment. Please note that the values listed below for soil conditions observed at the locations of borings B-1 and B-2 are relative to the ground surface elevation at the boring locations. Table 11: IBC Non-constrained Pole Lateral Bearing Pressure ZGA Boring Recommended Lateral Bearing Pressure(lbs/ft2/ft)of Embedment Depth',' B-7 0.5 to 2 feet: 160 2 to 7.5 feet:270 B-8 1.5 to 2 feet: 175 2 to 3.8 feet: 240 3.8 to 9.5 feet: 200 9.5—15 feet: 160 B-1-90 1.5—12.5 feet: 190 12.5—26.5 feet: 210 B-2-90 1.5—6 feet: 250 6—24 feet: 200 B-3-90 1.5—6 feet: 170 6—26.5 feet:250 Page 20 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 Table 11: IBC Non-constrained Pole Lateral Bearing Pressure B-4-90 1.5—7.5 feet: 120 7.5—18 feet:260 18—29 feet: 180 1. Values incorporate a factor of safety=2.5 2. Neglect upper 1.5 feet Concrete Slab Subgrade Preparation Recommendations The following subgrade preparation recommendations should be implemented in association with the construction of new concrete slabs, such as the one that will support the new control enclosure. Slab subgrade soils are anticipated to generally consist of at least medium dense granular soil, although some variation in this condition should be expected given the history of prior site grading. We recommend compacting the slab subgrades to a firm and non-yielding condition and to at least 95 percent of the modified Proctor maximum dry density prior to placing a crushed rock leveling course and prior to forming the slabs. Provided that the slab subgrades are prepared as described herein, we anticipate that total settlement will be negligible. Stormwater Infiltration Considerations The District's substations are frequently equipped with a perforated pipe installed around the yard perimeter or in other applicable locations that serves to allow infiltration of stormwater collected from the yard and impervious surfaces. Our scope of services did not include field infiltration testing. However, conclusions regarding stormwater infiltration can be drawn from subsurface conditions disclosed by the subsurface explorations and laboratory testing completed to date. We understand that surface water management for the project will be addressed in accordance with the design criteria presented in the Washington State Department of Ecology Stormwater Management Manual for Western Washington(2012,amended in 2014)as adopted by the City of Arlington. The Ecology manual allows establishing a preliminary infiltration rate (saturated hydraulic conductivity) for normally consolidated soils based upon the grain size distribution of the site soils utilizing methods presented in Section 3.3.6 of the manual. Saturated Hydraulic Conductivity The manual allows a determination of a stormwater receptor soil saturated hydraulic conductivity to be estimated based on grain size distribution characteristics in accordance with the following formula: Log10(Ksat,initia,) _ -1.57+ 1.9D10+0.015D60—0.013D90-2.08fti,,,where: Dio=grain size diameter(mm)for which 10 percent of the sample by weight is finer Page 21 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 D60=grain size diameter(mm)for which 60 percent of the sample by weight is finer D90=grain size diameter(mm)for which 90 percent of the sample by weight is finer ff;ne,=fraction of the sample by weight that passes the US No. 200 sieve. The calculated hydraulic conductivity values for four representative samples of the site soils are listed in the table below. Table 12: Saturated Hydraulic Conductivity Summary Boring/Sample Approximate sample depth Approximate Saturated Hydraulic (feet) Conductivity(centimeters per second/inches per hour) B-8/S-3 5-6.5 3.14 X 10-3/4.5 B-8/S-5 10—11.5 3.1 X 10-3/4.4 B-2-90/S-2 8 5.7 X 10-3/8 B-4-90/S-1 3 4.1 X 10-3/6 The saturated hydraulic conductivity values of the site's granular soils may be considered favorable for stormwater infiltration. Please note that the actual design baseline infiltration rate may need to be based upon the results of field testing completed in accordance with the current stormwater manual adopted by the City of Arlington. On a preliminary basis,we recommend that a baseline saturated hydraulic conductivity of 4 X 10-3 cm/sec be considered when evaluating infiltration system design. The manual requires applying correction factors to the baseline infiltration rate, whether determined by the grain size method or via field infiltration testing. Table 3.3.1 Correction Factors to be Used with In-Situ Saturated Hydraulic Conductivity Measurements to Estimate Design Rates of the manual calls for 40 percent reduction of the baseline rate. Table 3.3.1 also requires applying correction factors for site variability and number of locations tested (CF.) and the degree of influent control to prevent siltation and bio-buildup(CF,). Given the variability of the shallow soil conditions at the site we recommend applying CF,, and CF, factors of 0.8 and 0.9, respectively. Storage Considerations In the event that it becomes necessary to provide some storage capacity in the yard given the low effective infiltration rate of the site's soils, it would be feasible to include a layer of imported crushed rock with a high void ratio below the yard rock. We collected a sample of processed material meeting the gradation specification for Crushed Surfacing— Base Course as described in WSDOT 9-03.9(3) from Cal Portland of Everett, Washington and completed a permeability test in order to determine its usefulness in terms of Page 22 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 providing benefits in terms of stormwater management. The sample was compacted to approximately 95 percent of the modified Proctor maximum dry density in order to replicate its condition in the substation and tested for permeability via the ASTM D 2434 methodology. The sample was found to have a saturated hydraulic conductivity of 2.2 X 10-2 cm/sec (30.8 inches/hour). In the past the District has had laboratory testing completed on crushed surfacing base course sourced from the Iron Mountain Quarry in Granite Falls, Washington. Samples of this material have been shown to have a permeability of 130 inches/hour and void ratio of over 40 percent. The Iron Mountain Quarry products are 100 percent crushed rock and no naturally occurring sand is blended with crushed rock to produce the finished product. Consequently, the crushed products from Iron Mountain Quarry tend to have a high permeability and void ratio compared to other local vendor products that combine crushed rock and naturally occurring sand. Groundwater Considerations Groundwater was observed at depths of approximately 6 to 13 feet while drilling at the Dames & Moore boring locations;groundwater was not observed at the locations of borings B-7 and B-8 advanced for our current evaluation. Groundwater at the previously observed depths is not expected to adversely affect infiltration of stormwater through the yard or a perimeter infiltration trench system. Erosion Control Construction phase erosion control activities are recommended to include measures intended to reduce erosion and subsequent sediment transport. We recommend that the project incorporate the following erosion and sedimentation control measures during construction: • Capturing water from low permeability surfaces and directing it away from bare soil exposures. • Erosion control BMP inspection and maintenance: The contractor should be aware that inspection and maintenance of erosion control BMPs is critical toward their satisfactory performance. Repair and/or replacement of dysfunctional erosion control elements should be anticipated. • Undertake site preparation, excavation, and filling during periods of little or no rainfall. • Cover excavation surfaces with anchored plastic sheeting if surfaces will be left exposed during wet weather. • Cover soil stockpiles with anchored plastic sheeting. Page 23 Zipper Geo Associates, LLC East Arlington Substation Site Improvements Project No. 1643.0113 15 September 2016 • Provide an all-weather quarry spall construction site entrance. • Provide for street cleaning on an as-needed basis. • Protect exposed soil surfaces that will be subject to vehicle traffic with crushed rock or crushed recycled concrete to reduce the likelihood of subgrade disturbance and sediment generation during wet weather or wet site conditions. • Install perimeter siltation control fencing on the lower perimeter of work areas. • If grounding wells are installed,containment of the cuttings produced during the drilling process will reduce the likelihood of off-site sediment migration. Cuttings with a high fines content should be removed from the site following completion of drilling. CLOSURE The analysis and recommendations presented in this report are based, in part, on the explorations completed for this study. The number, location, and depth of the explorations were completed within the constraints of budget and site access so as to yield the information to formulate our recommendations. Project plans were in the preliminary stage at the time this report was prepared. We therefore recommend we be provided an opportunity to review the final plans and specifications when they become available in order to assess that the recommendations and design considerations presented in this report have been properly interpreted and implemented into the project design. The performance of earthwork, structural fill,foundations, and pavements depend greatly on proper site preparation and construction procedures. We recommend that Zipper Geo Associates, LLC be retained to provide geotechnical engineering services during the earthwork-related construction phases of the project. If variations in subsurface conditions are observed at that time, a qualified geotechnical engineer could provide additional geotechnical recommendations to the contractor and design team in a timely manner as the project construction progresses. This report has been prepared for the exclusive use of Snohomish County PUD No. 1, and its agents, in accordance with locally accepted geotechnical engineering practice. No other warranty, express or implied, is made. Page 24 'STABLISHED BY GPS II I i I i a N 89'5824" E 3 N ,. .. .. ,. I `� 360.00' x x ' a I T CHAIN LINK _ W/3 STRANDS B_2_90 ❑ d I 3 BARB WIRE x❑ ❑ ❑ ALL SIDES / a x I 3 I B-8 ❑ ❑ I I IF`'� � � ❑ VERTICAL ELEC. CONDUIT(TYP.) I ® ® ® m 6x6 STEEL POST(TYP.) r; I �I A. I I ❑ ❑ ❑ B-1-90 ❑ B-7 � ❑ I I I I 3 I I J ❑ x ° ° ❑ x ❑ � ❑ � ❑ LEGEND o ❑ I I / 3 CONC. PAD (TYP.)I A< xx x I B-7 ZGA BORING NUMBER AND I ❑ ❑ ❑ Q El ° ° El ° I APPROXIMATE LOCATION El I ti I I ARBORVIT: j /a 2'W 0 B-1-90 DAMES& MOORE 1991 I ❑ ❑ ❑ ° CHAIN LINK If BORING NUMBER AND a TEEL SHEDS FENCEALLSIDES i APPROXIMATE LOCATION MULTIPLE. I ❑ ElON CONC. J D 0/H POWER LINES PAD i n. I PRECAST CABLE TRENCH (TYP.) ❑ --,�+.--.- --..- ,' �i W 60 0 30 60 ®I ❑ ❑ ---D--—-- ---_J� APPROXIMATE SCALE IN FEET ❑ ❑ ❑ J , a I ❑ ❑ ARBORVITAE I 8'W a CC) I STEEL SHED I J I WOOD BOARD FENCE/GATE FS8 I I a ON CAOONC. I / CB SOLID LID RIM=161.26 a I ® ® I I 18"CMP E IE=156.96 D 18"CMP N IE=156.96 I a I I 6"PVC S IE=158.46 3 d AIN LI K o I CB RIM=15737 CB RIM=1 .60 6"PVC N IE=15959.40 3 PVC W E=154.72 I I ® ® j l l 4"PVC E CAPPED I IIE=154.72 -r-------1-56-- a� 3 B-3-90 - . _�� -P p P P - ► �fl �fl B6' �fl B-4-90 �ARBOR VITAE 6'W ARBOR-VITAE 6'W �r ----- N 89'5824" E 360.00' ur—O�r ur in 3 �� 1 -- UT UT UT UT UT UT G G- v = SD—SD—SD SD SD 3G G G G G G G G G G G G G G G G G. G G G G G�S US OS Ob = CENTER LINE, DBL YELLOW T PROPOSED EAST ARLINGTON 212 th ST (T VEI T RD). v �b a 1rja IL K� I c SUBSTATION IMPROVEMENTS ARLINGTON,WASHINGTON SITE AND EXPLORATION PLAN DATE:SEPTEMBER 2016 Job No. 1643.01 B Zipper Geo Associates,LLC FIGURE 19023 36th Ave.W.,Suite D FIGURE TAKEN FROM DRAWING S-4-P12N, DATED 16 MAY 2016, PROVIDED BY SNOHOMISH COUNTY PUD NO.1 AND ZGA FIELD MEASUREMENTS Lynnwood,WA,98036 SHT.1 of 1 APPENDIX A FIELD EXPLORATION AND TESTING PROCEDURES AND LOGS FIELD EXPLORATION AND TESTING PROCEDURES AND LOGS Our field exploration program for this project included completing a visual reconnaissance of the site and advancing two borings (13-7 and B-8)at the approximate exploration locations shown on Figure 1,the Site and Exploration Plan. Exploration locations were determined in the field using steel and fiberglass tapes by measuring distances from existing site features shown on the Assembly Plan, Drawing S-4-P11N (undated), provided by the District. As such,the exploration locations should be considered accurate to the degree implied by the measurement method. The ground surface elevation at each exploration location was interpolated from contours shown on the Topographic Map, East Arlington Sub-Station, dated 11 July 2016, prepared by Harmsen & Associates, Inc. The following sections describe our procedures associated with the explorations. Descriptive logs of the explorations are enclosed in this appendix. Boring Procedures The borings were advanced using a track-mounted drill rig operated by an independent drilling company working under subcontract to ZGA. The borings were advanced using hollow stem auger drilling methods. An engineering geologist from our firm continuously observed the borings, logged the subsurface conditions encountered, and obtained representative soil samples. All samples were stored in moisture- tight containers and transported to our laboratory for further evaluation and testing. Samples were generally obtained by means of the Standard Penetration Test at 2.5-foot to 5-foot intervals throughout the drilling operation. The Standard Penetration Test (ASTM D 1586) procedure consists of driving a standard 2-inch outside diameter steel split spoon sampler 18 inches into the soil with a 140-pound hammer free falling 30 inches. The number of blows required to drive the sampler through each 6-inch interval is recorded, and the total number of blows struck during the final 12 inches is recorded as the Standard Penetration Resistance, or "blow count" (N value). If a total of 50 blows are struck within any 6-inch interval, the driving is stopped and the blow count is recorded as 50 blows for the actual penetration distance. The resulting Standard Penetration Resistance values indicate the relative density of granular soils and the relative consistency of cohesive soils. The enclosed boring logs describe the vertical sequence of soils and materials encountered in each boring, based primarily upon our field classifications. Where a soil contact was observed to be gradational, our logs indicate the average contact depth. Where a soil type changed between sample intervals,we inferred the contact depth. Our logs also graphically indicate the blow count, sample type, sample number, and approximate depth of each soil sample obtained from the boring. If groundwater was encountered in a borehole,the approximate groundwater depth and date of observation are depicted on the log. Please note that borings B-7 and B-8 were both terminated due to electrical shock problems while drilling. The reason for the shocks experienced by the drilling crew could not be determined,so the District Safety Watch concluded that the drilling and sampling should be terminated. Sample Screening The boring logs also include the results of sample container headspace measurements taken with a RAE Systems photoionization detector (PID). The measurements indicate the relative concentration of petroleum hydrocarbons in the headspace air, but do not identify the type of hydrocarbon. The sample headspace readings, recorded as hydrocarbon concentration in parts per million (ppm) are presented on the logs in this appendix. The sample screening did not detect hydrocarbon levels of concern. Boring Location: See Figure 1A,Site and Exploration Plan Drilling Company: Boretecl Bore Hole Dia.:6" Top Elevation: 160 Feet Drilling Method: Hollow Stem Auger Hammer Type: Cathead B-7 Date Drilled: 6.2.16 Drill Rig: Track Logged by: DCW SOIL DESCRIPTION L PENETRATION RESISTANCE(blows/foot) a U) C J Standard Penetration Test o E E The stratification lines represent the approximate boundaries z d _0 m between soil types. The transition may be gradual. Refer to o Hammer Weight and Drop: o report text and appendices for additional information. � m a 0 20 40 60 0 11 2 inches coarse crushed rock above medium dense to very T I 1 dense,damp,gray-brown,gravelly SAND(Probable fill). S-1 I 18 0 -j 19 0.8 Drillingaction suggests the presence of coarse ravel and/or 1 gg p g . III IIIIIIIII Illlii cobbles. Blowcounts for samples S-2 and S-3 may be rr:- overstated. ( III II IIIIIIIII IIIIIII S-2 12 50/6 0.8 -f-I-I-f� -f -fT7TTTTTT TTTrrrr- IIIIIIIII IIIIIIIII 111111 ... �JJJJJII 1.1.1111.1.11 1LLL_ . IIIIIIIII IIIIIIIII IIII ' IIIIIIIII IIIIIIIII IIIIIII : 5 S-3 = 3 50/3 1.2 '.. IIIIIII IIIIIIIII IIIIIIII -I -4-4-F-I-4 44444-I-+-f-+ 4-.++-I-+- ' IIIIIIII IIIIIIIII IIII i (IIIIIIIII IIIIIIIII IIII ' �yrt-trtrtrt rtrty-tttttt tttt- IIIIIIIII IIIIIIIII IIII ' Boringterminated at 7.5 feet due to electrical shock. -7I7-7-7T77 T-TTT-TTTTT TTTrTT i F Groundwater not encountered ATD. 1 1 1 1 1 1 1 I I IIIIIIII IIIIIIIII 111111111 11111111 IIIIIIIII IIII II 11ii111 1111i11i1 ills II 10 i11111111 1111111 1111 II 11111111 11111111 1111 II 11 �t -+1+tt+.t.t+ tt.tt- I-.t--. 11111111 111111111 1111 II 11111111 111111111 111111111 _ IIIIIIII IIIIIIIII IIIIIIIII IIIIIIII IIIIIIIII IIIIIIIII _ IIIIIIII IIIIIIIII IIIIIIIII _ IIIIIIII IIIIIIIII IIIIIIIII 15 IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIII IIIIIIIII IIIIIIIII ' IIIIIII IIIIIIIII IIIIIIIII IIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIII _1i _[_trtrtrt rtrtttttttt tttttl-tt- IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIII IIIIIIII -1-I-7-1-7-f7 777T7TTTT TT77T7T - IIIIIIIII III � IIII � IIIIIII 20 IIIIIIIII IIIIIIIII IIII i l i i i M H i H N k i IIIIIIII iiliiiili iii111i1 11111111 111111111 IIII 111111111 111111111 1111 � � 111111111 111111111 IIIIIII ��trt�rtrtrt rtrtrtTTrt*TT rtrrrrrr- 25 SAMPLE LEGEND GROUNDWATER LEGEND O % Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand O %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonite Plastic Limit Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing East Arlington Substation TESTING KEY ❑ Blank Casing 21210 - 87th Avenue NE GSA=Grain Size Analysis V Groundwater level at Arlington, WA time of drilling(ATD)or 200W=200 Wash Analysis N on date of Date: 9.15.16 Project No.: 1643.01 B Consol. =Consolidation Test N measurement. Zipper Geo Associates BORING Att.=Atterberq Limits B-7 19023 36th Ave. W, Suite D LOG; Lynnwood, WA Page 1 of 1 Boring Location: See Figure 1B,Site and Exploration Plan Drilling Company: Boretecl Bore Hole Dia.:6" Top Elevation: 160 Feet Drilling Method: Hollow Stem Auger Hammer Type: Cathead B-8 Date Drilled: 6.2.16 Drill Rig: Track Logged by_: DCW SOIL DESCRIPTION L PENETRATION RESISTANCE(blows/foot) a U) C J Standard Penetration Test o E E The stratification lines represent the approximate boundaries z d _0 m between soil types. The transition may be gradual. Refer to o Hammer Weight and Drop: o report text and appendices for additional information. � m a 0 20 40 60 0 Loose to medium dense,moist,brown, sandy GRAVEL with © +-++++r t r some cobble-size quarry spalls(Fill) s-1 2 + 22 1.4 11 IIIIIIIII IIII III IIIIIIIII Illlii -------------------------------------------- Hard,wet,brown-gray, SILT I S-2 12 ITT f7 7T TTTTTT TT 7 - 46 0.7 -------------------------------------------- IIIIIIII IITIII JJJJJJII 111111L11 1L-LL_ . Medium dense,wet, brown, gravelly,silty SAND interbedded 5 with silty SAND with some gravel T '.. IlI11I11 IIIIIIIII Illlllli S-3 I 18 1 1 1 P +++I I I II I 1 1 1 1 1+++ 1 25 1.3 11 h4 I+ +#4++ + r IIIIIIII IIIIIIIII IIII IIIIIIII IIIIIIIII IIII . -Y-17 7rt�rtrtrt rttrt t t t.ttt t t..fi r r � � '`. IIIIIIIII IIIIIIIII IIIIIIII I S-4 18 26 0.7��TT�I�f� �� TTTTTTTTT-Tl-1-1-` IIIIIII IIIIIIII IIIIIII IIIIIIIII II, IIIII,II IITIII_! ;. IIIIIIIII IIIIIIIII IIII ' 10 T S-5 I 18 16 1.7 IIIIIIII IIIIIIIII Ili IIIIIIII IIIIIIIII IIII ".. '.. - IIIIIIII IIIIIIIII IIII ' TIIIIIIII IIIIIIIII IIIIIII : S-6 I 18 T7� T�7 rtrt t TTTT TTTTTT 11 0.7 III� III IIIIIIIII IIIIIII . IIIIIII IIIIIIIII IIIIIIII 15 Boring terminated at 15 feet due to electrical shock. Groundwater not observed ATD. - Illliill IIIIIIIII liilll IIIIIII IIIIIIIII IIII IIIIIIIII -i-i��rt�rtrtrt rtrtrtttt+tt trrrrrr..�i- iillliill iillliill IIIIIIIII iilliiill iilliiill IIIIIIIII -177-17 f7 77TTTTTTT TTT-l-T7T 7- IIIIIIIII IIIIIIIII IIIIIIII 20 IIIIIII iiliiiiii IIII IIIIIII IIIIIIIII IIII IIIIIII iiliiiili iii111i1 IIIIIII iilliiill IIII IIIIIIII iilliiill IIIII � IIIIIIII iilliiill iiillll 11111111 "444 *Trt rt"""- 25 SAMPLE LEGEND GROUNDWATER LEGEND O % Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand O %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonite Plastic Limit Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing East Arlington Substation TESTING KEY ❑ Blank Casing 21210 - 87th Avenue NE GSA=Grain Size Analysis V Groundwater level at Arlington, WA time of drilling(ATD)or 200W=200 Wash Analysis N on date of Date: 9.15.15 Project No.: 1643.01 B Consol. =Consolidation Test N measurement. Zipper Geo Associates BORING p Att.=Atterberq Limits B-p 19023 36th Ave. W, Suite D LOG; Lynnwood, WA Page 1 of 1 APPENDIX B BORING LOGS BY OTHERS APPENDIX B BORING LOGS BY OTHERS This appendix contains descriptive logs of four borings advanced by Dames&Moore in January 1991. The approximate locations of the borings are shown on the Site and Exploration Plan, Figure 1B. BORING B- 1 - 90 o ,�.o� q* 4�' q„ ,�� Surface Elevation: 340.0± .f--4 0 GM . medium gravel (base course) (loose) Brown silty medium gravel (wet) (base course) edium dense) SM Brown silty fine sand with traces of fine to coarse gravel end traces of clay (damp) (medium dense) I5.1 125 18 Grades with interbedded brown medium sand layers 1 gbi Bluish ray silty fine sand with traces of fine 10.4 134 18 gravel moist/damp) (medium dense) 15 Increasing gravel and trace of clay 13.0 124 28 i i 20 10.1 131 31 i GM Bluish gray silty tine to coarse gravel with (aces of clay and traces of medium Band wet) (medium dense) 25 0 27 0° Boring completed at a depth of 28.5 feet on 1-2-91. Groundwater encountered at a depth of 10 feet during drilling, CQ 0 30 � f S .� 35 i t 0 w rs LOG OF BORING Darnes & Moore Plate A— 1 Job No. 03229-006-016 BORING B-2- 90 o o g a,4 4) Surface Elevation' 340.01 � 0-7 gavel (base course) 'y'':?; Sp Brown medium sand with fine to medium gravel and traces of silt (dense) { 13.8 123 48 «j. SM Bluish gray sad brown silty fine sand with traces f fine to coarse gravel and traces of clay medium dense) (damp) 18 -10 34 ® Bluish gray below 12.5' (dense) (wet) i5 9.3 134 30 I 20 € 11.0 122 24 Boring completed at a depth of 24 feet on 1-2 91. 25 Possible perched water table encountered at 13' during drilling. 0 w Co. N 0 a 30 0 I CU Cr ,. 35 Co. 0 i 1 W Q p o Dames & Maare -� LOG OF BORING Plate A— 2 Job No. 03229-006-016 BORING B-3- 9O Sp Brown gravelly medium sand with traces of silt (damp) (loose to medium dense) ".4i. :'•� 40 v:; Brownish gray and medium dense below B' :. :Sl. 10 12.4 124 38 GM Bluish gray silty fine gravel (inedium dense) 15 50/4' ® kL Blue to gray silty fine sand with occasional fine to coarse gravel (moist) {very dense} I Increasing gravel at 20' i 20 8.9 135 50 25 e 10.6 129 31 MBorin completed at a depth of 26.5 feet. ,y possife perched groundwater encountered at a I depth of B'. N Q F 30 Cr ,� 35 w I I 0 W " Dames & Moore s LOG OF BORING Plate A— 3 Job No. 03229-006-016 BORING B -4-90 Al Surface Elevation. W-+ G GIA Silty fine to medium gravei (bass course) (wet) i SM Resh (fill) (n silty fine sand with wood fragments d fill kxise 4 1 5 Harder dn111ng at about 5' Grades with increasing gravel GM Grayish Been Bitty flne to coarse gravel (dance 8.2 50/5' to very dense) Grades grayer at 9.5 10 Grades back to brown at 10.5 7.9 112 46 Grades wet at about 13.5 to 14 15 14.6 96 22 ® fls" g inch ?wet)s medium dansa tth occaslonal fine 20 Gld Cray find to coarse grovel (wet) (medium dense 20 25 o SM Cray sfity fine sand with Geese w� e(rnsdium b� grovel and traces of days( ) i 30 IT BorfN completed of a depth of 29 feat on 1 0 Ground drlllirsg cantered at depths of 13'-14' 30 piezometer installed with tlp depth of about 29' slotie Green from 291-18') (blank screen frorn gsand gpock to 17 depth) Grour adwctPovtitlee(aboutd6ahoursa after completion of instollotfon of the plezometer.) i i 35 ft 4 LOG OF BORING Dames & Moore Plate A— 4 Job No. 03229-006--016 KEY: Indicates depth at which undisturbed Dames & Moore sample was extracted. 3 ® Indicates depth at which disturbed Dames & Moore sample was extracted. ® Indicates depth at which Dames & Moore sample was attempted with no recovery. ® Indicates depth at which Split Spoon sample was extracted. Indicates depth at which Split Spoon sample was attempted with no recovery. i ® Indicates depth at which Grab sample was collected. i i NOTE: Blows per foot indicates number of blows required to drive the Dames & Moore sampler the last 12 inches of a total 18 inches run with a 300 pound hammer and a 30—inch drop. I i i KEY Dames & Moore Job No. 03229-006-016 Plate A—5 APPENDIX C LABORATORY TESTING PROCEDURES AND RESULTS LABORATORY PROCEDURES A series of laboratory tests were performed during the course of this study to evaluate the index and geotechnical engineering properties of the subsurface soils. Descriptions of the types of tests performed are given below. Visual Classification Samples recovered from the exploration locations were visually classified in the field during the exploration program. Representative portions of the samples were carefully packaged in moisture tight containers and transported to our laboratory where the field classifications were verified or modified as required. Visual classification was generally done in accordance with ASTM D 2488. Visual soil classification includes evaluation of color, relative moisture content, soil type based upon grain size, and accessory soil types included in the sample. Soil classifications are presented on the exploration logs in Appendix A. Moisture Content Determinations Moisture content determinations were performed on representative samples obtained from the explorations in order to aid in identification and correlation of soil types. The determinations were made in general accordance with the test procedures described in ASTM D 2216. The results are shown on the exploration logs in Appendix A. Grain Size Analysis A grain size analysis indicates the range in diameter of soil particles included in a particular sample. Grain size analyses were performed on representative samples in general accordance with ASTM D 422. The results of the grain size determinations for the samples were used in classification of the soils, and are presented in this appendix. Laboratory Maximum Density Test The laboratory maximum density represents the highest degree of density which can be obtained from a particular soil type by imparting a predetermined compaction effort. The test determines the "optimum" moisture content of the soil at the laboratory maximum density. The laboratory maximum density test was performed in general accordance with ASTM D 1557 on a sample of crushed surfacing base course sourced from Cal Portland in Everett, Washington prior to completing a permeability test, and the results are presented in this appendix. Permeability of Granular Soils(Constant Head Method) The coefficient of permeability (hydraulic conductivity) of the sample of crushed surfacing base course sourced from Cal Portland in Everett, Washington was determined in general accordance with the ASTM D 2434 testing procedure. The testing was completed on the sample after it had been compacted to approximately 95 percent ofthe modified Proctor maximum dry density per ASTM D 1557. The test results are summarized in this appendix and discussed in the report text. GRAIN SIZE ANALYSIS Test Results Summary ASTM D 422 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 1 1/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 Im 60 LLI Z 1.— 50 Z W tU W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS Coarse Fine ::h Medium Fine Silt Clay BOULDERS COBBLES GRAVEL FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description B-8 S-3 5-6.5 12.5 37.0 Gravelly siltySAND Project No.: 1643.01 B PROJECT NAME: Zipper Geo Associates, LLC Geotechnical and Environmental Consultants DATE OF TESTING: 6/9/2016 East Arlington Substation GRAIN SIZE ANALYSIS Test Results Summary ASTM D 422 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 1 1/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 Im 60 LU Z M 1.— 50 Z LU tU W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS Coarse Fine ::h Medium Fine Silt Clay BOULDERS COBBLES GRAVEL FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description B-8 S-5 10- 11.5 10.5 39.6 Gravelly siltySAND Project No.: 1643.01 B PROJECT NAME: Zipper Geo Associates, LLC Geotechnical and Environmental Consultants DATE OF TESTING: 6/9/2016 East Arlington Substation ULM.", HWAGEOSCiENCES INC. C;rate:cluiical Er>'gincerirrg 'ftydr�ogcolo � Geoerrvirnnmen!.ul ^Inspection and restir:,g June 6,2016 HWA Project No. 2012-102-23, Task 1100 Zipper Geo Associates, LLC 19023 36th Ave W, Suite D Lynnwood,Washington 98036 Attention: Mr. David Williams,LG, LEG Subject: Soil Laboratory Testing Report Hydraulic Conductivity and Compaction Testing East Arlington-Oso Substation Project Dear Mr. Williams: As requested,HWA GeoSciences Inc. (HWA)performed laboratory testing for the above referenced project. Herein we present the results of our laboratory analyses,which are summarized on the attached report. The laboratory testing program was performed in general accordance with your instructions and appropriate ASTM Standards as outlined below. SAMPLE DESCRIPTION: The subject sample was delivered to our laboratory on May 31,2016 by Zipper Geo Associates(ZGA)personnel. The sample of Crushed Surfacing Base Course (CSBC)was delivered in two 5-gallon buckets and was designated with the Zipper Geo sample number"052616". LABORATORY COMPACTION CHARACTERISTICS OF SOIL(PROCTOR TEST): The moisture/density relationship for the submitted sample was determined in general accordance with method ASTM D1557(Modified Proctor)Method C. The test results are summarized on the attached Laboratory Compaction Characteristics of Soil report,Figure 1. PERMEABILITY OF GRANULAR SOILS(CONSTANT HEAD METHOD): The coefficient of permeability(also commonly referred to as hydraulic conductivity) of the material was measured in general accordance with method ASTM D2434. The sample was compacted in the test apparatus to approximately 95%of the Maximum Dry Density(MDD)as determined by ASTM D1557 without gravel correction. Subsequently,the sample was saturated and testing was conducted using a flow gradient of about 0.3. The test results are summarized in Table 1. 21312 3&Drive SE Suite 110 Bothell,WA 98021-7010 Tel:425.774.0106 Fax:425,774.2714 www.hwageo.com June 6,2016 HWA Project No.20.12-102 T1100 Table 1 Summary of Constant Head Permeability Testing Results Sample Moisture Dry Density Hydraulic Permeability Designation Content (Pct) Conductivity (in/hour) (%) (cm/sec) 052 116 7.5 132.9 2.2 x 10 2 30.8 O•0 CLOSURE: Experience has shown that laboratory test data for soils and other similar materials vary with each representative sample. As such,HWA has no knowledge as to the extent and quantity of material the tested sample may represent. HWA also makes no warranty as to how representative either the sample tested or the test results obtained are to actual field conditions. It is a well established fact that sampling methods present varying degrees of disturbance or variance that affect sample representativeness. No copy should be made of this report except in its entirety. We appreciate the opportunity to provide laboratory testing services on this project. Should you have any questions or comments,or if we may be of further service,please call. Sincerely, HWA GEOSCIENCES INC. Daniel Walton Steven E. Greene,LG, LEG Materials Laboratory Technician Principal Engineering Geologist Attachments: Figure 1 Laboratory Compaction Characteristics of Soil T1100 Letter Report 2 HWA GeoSciences Inc. 3i yl yF. LABORATORY COMPACTION CHARACTERISTICS OF SOIL CLIENT: Zipper Geo HWAGEOSCIENCES INC. PROJECT: East Arlington-Oso Substation Project SAMPLE ID: 52616 PROJECT NO: 2012-102 T1100 Sampled By: Client Tested By: DW Date Sampled: NA Date Received: 513112016 Date Tested: 612f2016 MATERIAL TYPE OR DESCRIPTION: Crushed Surfacing Base Course CSBC MATERIAL SOURCE, SAMPLE LOCATION AND DEPTH: NIA Designation:QASTM D 698 FX ASTM D 1557 Natural Moisture Content: 2.7 % Method: r-JA B QC Oversize: 12.2 % retained on: 314 in. Preparation:QDry QX Moist Rammer:[ Auto Manual Assumed S.G.: 2.85 Test Data Dry Density cf) 1 134.5 139.9 1 140.3 1 136.E Moisture Content(%) 4.6 6.5 8.3 1 10.1 145 Rock Corrected Curve per ASTM D4718 �--� Lab Proctor Curve ....... 100%Saturation Line _ ..............-- -- 140 a d G 135 130 2 4 6 8 10 12 14 Moisture Content Data Summary* Test Values At Other Oversize Percentages Percent Oversize 12.2% 0.0% 5.0% 10.0% 15.0% 20.0% 25.0% 30.0% Max.Dry Density(pcf)* 144.3 140.6 142.1 143.6 145.2 146.8 148.4 150.6 Optimum Moisture(%)* 6.7 T5 7.2 6.9 A 5 6.2 5.9 5.6 values corn r ovens ze ma r per AST 4 D4718,using assumed Specific Gravity shown a d size m ontent of 1% Reviewed By: FIGURE 1 This report applies only to the items tested,and may be reproduced in full,with written approval of HWA GEOSCIENCES INC. GRAIN SIZE ANALYSIS Test Results Summary ASTM D 422 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 1 1/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 Im 60 LU Z 50 Z W U W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS Coarse Fine ::h--Nrs- Medium Fine Silt Clay BOULDERS COBBLES GRAVEL FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description Cal Portland, 052616 grab 2.1 6.8 Sandy GRAVEL, Everett some Fines Project No.: 1643.01 PROJECT NAME: Zipper Geo Associates, LLC Geotechnical and Environmental Consultants DATE OF TESTING: 5/31/2016 East Arlington -Oso Substation SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE Purpose of Checklist: The State Environmental Policy Act (SEPA), chapter 43.21 C RCW, requires all governmental agencies to consider the environmental impacts of a proposal before making decisions. An environmental impact statement (EIS) must be prepared for all proposals with probable significant adverse impacts on the environment. The purpose of this checklist is to provide information to help the Responsible Official of the Public Utility District No. 1 of Snohomish County (the District), and any other agencies with jurisdiction, to identify impacts from a proposal (and to reduce or avoid impacts from the proposal, if it can be done) and to help the District decide whether an EIS is required. A. BACKGROUND 1. Name of proposed project, if applicable: East Arlington Substation 2. Name of applicant: Public Utility District No. 1 of Snohomish County (the District or Snohomish PUD) 3. Address and phone number of applicant and contact person: P.U.D. No. 1 of Snohomish County P.O. Box 1107 Everett, WA 98206-1107 Project Leader/Contact Person: Tom Hendricks Phone: (425) 783-5022 4. Date checklist prepared: January 3, 2018 5. Agency Requesting Checklist: Public Utility District No. 1 of Snohomish County 6. Proposed timing or schedule (including phasing, if applicable): • Substation design in 2017 and first quarter 2018 • Permitting in first quarter 2018 • Site construction July 2018 through October 2018 • Substation electrical construction January 2019 through May 2019 with energization in 2019 7. Do you have any plans for future additions, expansion, or further activity related to or connected with this proposal? If yes, explain. Yes. Ongoing maintenance of all equipment, conductor, poles, stormwater system, landscaping, site access driveways, and other appurtenances as needed to maintain the facility and preserve electrical system reliability. Future plans may include necessary vegetation management, upgrades in capacity, and other routine utility repair or maintenance within the substation facility and utility corridor. 8. List any environmental information you know about that has been prepared, or will be prepared, directly related to this proposal. Page 1 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE • Geotechnical Engineering Report prepared by Zipper Geo Associates, LLC, dated September 15, 2016. • Critical Area Determination Report prepared by Wetland Resources, Inc., dated July 2016 and revised January 25, 2017. • Sound Analysis, prepared by BRC Acoustics &Audiovisual Design, dated October 12, 2016. • Cultural Resources Survey East Arlington Substation Addendum to the Eagle Creek Substation Report prepared by Tierra Right of Way, dated May 30, 2017. 9. Do you know whether applications are pending for governmental approvals of other proposals directly affecting the property covered by your proposal? If yes, explain. No. 10. List any government approvals or permits that will be needed for your proposal, if known. Snohomish PUD: • SEPA Checklist and Threshold Determination Washington State Department of Ecology: • Construction Stormwater General Permit 11. Give a brief, complete description of your proposal, including the proposed uses and the size of the project and site. There are several questions later in this checklist that ask you to describe certain aspects of your proposal. You do not need to repeat those answers on this page. Proposal: To replace the existing East Arlington 115kV single bus with a six breaker ring bus with Smart Grid capability. This project is part of the Snohomish PUD Electric System Capital Program to provide additional electrical capacity and significantly improve electric service reliability to the City of Arlington and the northern Snohomish County service area. The existing East Arlington Substation is located on the eastern portion of a 1.66 acre parcel in the City of Arlington, WA. Construction of the substation site will consist of.• • Demolition of the existing equipment, structural steel, concrete foundations, control enclosures, cable trench, conduit, ground grid, and security fence with the exception of the common fence with the Navy's Area 51 yard. • The substation will generally consist of: a) A 1.0 acre substation yard surfaced with crushed rock. The yard will be enclosed with a security fence in compliance with the National Electric Safety Code. b) Six Transmission line termination (dead-end) structures c) Six 115kV Circuit Breakers d) One Control Enclosure Page 2 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE e) 115kV Switches, EMVTs, and Arrestors f) Overhead Bus and Conductors g) Grounding System h) Underground Conduits and Conductor i) Other improvements at the substation include: a site drainage system; access driveways for ingress and egress with access control gates; and site landscaping with irrigation. Transmission and distribution line construction associated with this project will include: Reconductoring the transmission poles between the East Arlington and Oso Substations. 12. Location of the proposal. Give sufficient information for a person to understand the precise location of your proposed project, including a street address, if any, and section, township, and range, if known. If a proposal would occur over a range of area, provide the range or boundaries of the site(s). Provide a legal description, site plan, vicinity map, and topographic map, if reasonably available. While you should submit any plans required by the agency, you are not required to duplicate maps or detailed plans submitted with any permit applications related to this checklist. Tax Number: 31051200200500 Street Address: 21210 87'Avenue NE, Arlington, WA 98223 7 s rn(I) dt ARLINGTON R F,g, 4 16D � SR � _, ? 204TH ST NE CEM RT$� r g PROJECT SITE 21210 87TH AVE NE ARLINGTON,WA 98223 Vicinity Map NW%, SEC 12, TWP 31N, R 5E, W.M. Page 3 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE Legal Description: Per Deed Recorded under Auditor's file number 927207 & 927174. Commencing 20 Feet North 3° East of the SE Corner of the SW'/4 of the NW '/4 of Section 12, Township 31 N., Range 5 E., W.M.; thence North 3° East 200 Feet; thence South 870 30' West Parallel with the East and West Centerline of Said Section 12, 360 Feet; thence South 30 West 200 Feet; thence North 870 30' East 360 Feet to the Point of Beginning. Subject to Unrecorded Perpetual Easement over and across the westerly portion thereof, for the maintenance and operation of two 110,000 volt lines of Puget Sound Power& Light Company known as Baker River No. 1 and Baker River No. 2. B. ENVIRONMENTAL ELEMENTS 1. Earth a. General description of the site (Underline one): Flat, rolling, hilly, steep slopes, mountainous, other b. What is the steepest slope on the site (approximate percent slope)? The generally flat ground surface elevation in the main yard is at or near 160 feet, and there is a small hump at elevation 162 near the northwest corner where the steepest slope is possibly 17%. c. What general types of soils are found on the site (for example, clay, sand, gravel, peat, muck)? If you know the classification of agricultural soils, specify them and note any agricultural land of long-term commercial significance and whether the proposal results in removing any of these soils. In the US Department of Agriculture's 1983 Soil Survey of Snohomish County Area Washington the on-site soils are mapped mostly as Everett very gravelly sandy loam. The 2016 geotechnical report states the publication Geologic Map of the Arlington East Quadrangle, Snohomish County, Washington (US Geological Survey Map MF-1739, dated 1985) describes the site as underlain by the Marysville Sand member of recessional outwash deposits. However, based upon the conditions disclosed by the borings completed on the site, it appears that the native soils are more representative of the glacial till which has been mapped to the southeast and northwest of the site and underlies the recessional deposits. There is no agricultural land of long-term significance in the vicinity. d. Are there surface indications or history of unstable soils in the immediate vicinity? If so, describe. No. e. Describe the purpose, type, total area, and approximate quantities and total affected area of any filling, excavation, and grading proposed. Indicate source of fill. Page 4 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE Approximately 75 % of the 1.66 acre site will be affected by the land disturbing activities. Approximate earthwork quantities for the substation site and access driveways are: Cut + 1,800 cubic yards Fill + 2,500 cubic yards An unknown quantity may also be needed to replace excavated soil that is too wet to achieve proper compaction for use as trench or foundation backfill material. Granular fill material will be imported from a state approved licensed quarry within the Snohomish County area determined at the time of construction. Surplus and unsuitable soils (quantity not yet known) will be disposed of / off-site at an approved location selected by the construction contractor. c/ Unsuitable soils include cohesive, debris-filled and organic soils that cannot be used for backfill or foundation support. Such soils will be removed and replaced with imported granular, compactable soils, or controlled density fill material. f Could erosion occur as a result of clearing, construction, or use? If so, generally describe. The existing substation yard is essentially flat, so the potential for erosion is very low. Site excavation and grading during construction will expose soils and increase erosion potential, but proper precautions and BMPs implemented by the site construction contractor should prevent erosion. Once all permanent improvements are installed and vegetation / landscaping are established, the potential for erosion will be negligible. g. About what percent of the site will be covered with impervious surfaces after project construction (for example, asphalt or buildings)? Approximately 23.7% of the existing substation site is currently covered with impervious surfaces. After project construction, impervious surface coverage will be reduced to approximately 8.1%. h. Proposed measures to reduce or control erosion, or other impacts to the earth, if any: The Construction Stormwater Pollution Prevention (SWPP) Plan for the project will dictate appropriate BMP's for avoiding, preventing and minimizing erosion and sedimentation during construction. The SWPP Plan and implementation will comply with the City of Arlington stormwater regulations and the Washington State Department of Ecology Construction Stormwater General Permit. 2. Air a. What types of emissions to the air would result from the proposal (i.e., dust, automobile, odors, industrial wood smoke) during construction and when the project is completed? If any, generally describe and give approximate quantities if known. Short term direct emissions from vehicles and construction equipment will Page 5 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE occur during the specific construction phase of the project. Odors from construction materials may occur, engine exhaust will be present during construction, and dust may be generated during short term clearing and grading activities. A temporary increase in carbon dioxide, nitrous oxide and methane emissions from off road, on road and possibly stationary sources involved in the construction phase will occur during the period of active construction and discontinue when construction is complete. The greenhouse gas emissions associated with the active construction of the project are estimated to be as follows: Carbon dioxide: 117.3 metric tons Methane: 4.1 kilograms Nitrous oxide: 3.4 kilograms Total combined in CO2 equivalents: 118.5 metric tons The embodied greenhouse gas emissions associated with the use of steel, concrete, timber, asphalt, and fiberglass materials in the construction of the site are estimated to total 131.1 metric tons of CO2 equivalents. Long term emissions for the completed project are expected to remain consistent with existing emissions resulting from daily operations. These include emissions that may be associated with routine maintenance and / or repair of the completed project. b. Are there any off-site sources of emissions or odor that may affect your proposal? If so, generally describe. Off-site emission sources and climate change may have the potential to affect the proposal. The Puget Sound Clean Air Agency has established local ambient air standards for six criteria air pollutants and the Agency monitors and reports on these air quality observations annually. These criteria air pollutants are: • Particulate Matter(10 micrometers and 2.5 micrometers in diameter) • Ozone • Nitrogen Dioxide • Carbon Monoxide • Sulfur Dioxide • Lead Efforts to address air quality in the region have successfully achieved attainment for several of the criteria pollutants however observation sites in King, Pierce and Snohomish counties continue to exceed the Puget Sound Clean Air Agency local PM2.5 health goal for fine particulate matter. Observations at sites monitoring ozone indicate ozone levels remain a concern in the region. Carbon dioxide and methane are additional emissions of interest associated with climate change with the potential to affect weather conditions in the Snohomish County region. Potential impacts in the Pacific Northwest due to climate change have been assessed through the National Oceanic and Atmospheric Page 6 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE Administration U.S. Global Change Research Program, and summarized in the 2017 report titled "Climate Science Special Report: Fourth National Climate Assessment, Volume 1." The projected changes include declining springtime snowpack, reduced summer stream flows, warmer water temperatures, higher ambient temperatures and rising sea levels. Such changes could result in reduced water supplies, and thus the need to seek new sources or methods to meet future water demand. c. Proposed measures to reduce or control emissions or other impacts to air, if any: PUD No. 1 of Snohomish County has adopted a Climate Change Policy providing guidance to address planning and operational changes necessary to reduce greenhouse gas emissions from non-generation related activities and improve the energy efficiency of generation, transmission, distribution and administrative facilities. Total utility greenhouse gas emissions inclusive of all Snohomish PUD operations are also calculated and reported annually to the US Energy Information Agency under the 1606 (b) reporting program and this process is expected to continue. In addition, the PUD continuously monitors and evaluates weather events and projected climate conditions in order to address operational needs and for resource availability and conservation planning considerations. Both short term actions to address immediate weather conditions and longer r term planning to address seasonal changes in hydrologic conditions will continue to be implemented. In regard to the proposed project, all passenger vehicles and construction related vehicles and equipment are and will be properly maintained and will comply with applicable emission control devices and federal and state air quality regulations for exhaust pipe emissions. Operational measures to increase fuel efficiency and reduce fuel related emissions will be applied when practicable and attainable at reasonable cost. Idling of combustion engines will be minimized and equipment will be turned off when applicable. Erosion control and dust control measures will be addressed as needed. Best management practices to limit deposition of soil on roadways will be implemented and active dust suppression measures will be evaluated and applied as necessary. Dust during construction will also be controlled through street sweeping and wetting the construction area during dry weather. 3. Water a. Surface Water: 1) Is there any surface water body on or in the immediate vicinity of the site (including year-round and seasonal streams, saltwater, lakes, ponds, wetlands)? If yes, describe type and provide names. If appropriate, state what stream or river it flows into. No saltwater, lakes, or ponds exist in the immediate vicinity of the substation site. Page 7 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE The substation site is located within the Eagle Creek 4t"Tier Basin at the northwest corner of the intersection of Tveit Road and 871h Ave NE. The South Fork of the Stillaguamish River lies approximately 0.66 miles northeast of the site. The edge of the mapped floodplain associated with the river lies approximately 0.34 miles to the northeast. Referring to the January 25, 2017 revision of the Critical Area Determination Report for the East Arlington and Eagle Creek Substations prepared by Wetland Resources, Inc. and the Critical Area Determination Map on page 9, Eagle Creek flows through Wetland A and B east of the substation property. • Wetland A is classified as a Category II wetland with a Habitat Score of 7 and a 33% increased protective buffer of 219 feet. • Wetland B is also classified as a Category II wetland with a Habitat Score of 8 and a 33% increased protective buffer of 299 feet. • Wetland C is classified as a Category III wetland with a Habitat Score of 6 and a 33% increased protective buffer of 140 feet. • Washington Department of Fish and Wildlife reports that Eagle Creek is used by Coho Salmon, which is not listed as Threatened or Endangered species. As such, Eagle Creek would be classified under AMC 20.93.700 as a Type F Water. AMC Table 20.93-3 requires 100 foot buffers for Type F Waters. The buffers from Wetlands A, B, and C would technically cast onto the existing substation property, however, the East Arlington Substation was lawfully developed prior to the adoption of AMC 20.88 or 20.93, so it is considered a legal nonconforming use. The proposed redevelopment of the substation into a switching station will not change the extent of nonconformity as no expansion of the developed area will occur. As such, the proposed project is an allowed activity under AMC 20.93.820(4)(H). AMC 20.32.040(a) allows renovation of nonconforming situations in accordance with a zoning permit. Page 8 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE RI E3k�:r IF 71 246 CATEGORY 11 f(ABITAT A s - . s ' . � 1 ; i "l�El�dliP}iA �'•#i�Ei�- � ,t>� �.'.s_. --- N - - 1 Y SCORE Critical Area Determination Map 2) Will the project require any work over, in, or adjacent to (within 200 feet) the described waters? If yes, please describe and attach available plans. Yes, the substation project will require work within 200 feet of Wetlands A, B, C and Eagle Creek. 3) Estimate the amount of fill and dredge material that would be placed in or removed from surface water or wetlands and indicate the area of the site that would be affected. Indicate the source of fill material. None. 4) Will the proposal require surface water withdrawals or diversions? Give general description, purpose, and approximate quantities if known. No. 5) Does the proposal lie within a 100-year flood plain? If so, note location on the site plan. No. 6) Does the proposal involve any discharges of waste materials to surface waters? If so, describe the type of waste and anticipated volume of discharge. No. Page 9 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE b. Ground Water: 1) Will groundwater be withdrawn from a well for drinking water or other purposes? If so, give a general description of the well, proposed uses and approximate quantities withdrawn from the well. Will water be discharged to groundwater? Give general description, purpose, and approximate quantities if known. No. 2) Describe waste material that will be discharged into the ground from septic tanks or other sources, if any (for example: domestic sewage; industrial waste materials, agricultural wastes; etc.) Describe the general size of the system, the number of such systems, the number of houses to be served (if applicable), or the number of animals or humans the system(s) are expected to serve. None. c. Water Runoff(including storm water): 1) Describe the source of runoff(including storm water) and method of collection and disposal, if any (include quantities, if known). Where will this water flow? Will this water flow into other waters? If so, describe. The main source of runoff is rainfall, with the potential for minor runoff contributions from irrigation. The method of runoff disposal is to infiltrate and disperse stormwater on-site to the maximum extent feasible utilizing infiltration and dispersion BMP's in accordance with the City of Arlington stormwater regulations. Surface water runoff and interflow generated on-site will ultimately drain toward Eagle Creek. 2) Could waste materials enter ground or surface waters? If so, generally describe. No. 3) Does the proposal alter or otherwise affect drainage patterns in the vicinity of the site? If so, describe. No. d. Proposed measures to reduce or control surface, ground, and runoff water impacts, if any: Construction stormwater pollution prevention: The Construction Stormwater Pollution Prevention (SWPP) Plan for the project will dictate appropriate BMP's for preventing or minimizing erosion and sedimentation during construction. The SWPP Plan and implementation will comply with the City of Arlington stormwater regulations and the Washington State Department of Ecology Construction Stormwater General Permit. Permanent stormwater management: Stormwater runoff impacts will be mitigated using on-site stormwater management infiltration and dispersion BMP's in accordance with the City of Arlington stormwater regulations. Page 10 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE 4. Plants a. Check the types of vegetation found on the site: deciduous tree: alder, maple, aspen, other _X_evergreen tree: fir, cedar, pine, other shrubs X_grass pasture crop or grain orchards, vineyards or other permanent crops wet soil plants: cattail, buttercup, bullrush, skunk cabbage, other water plants: water lily, eelgrass, milfoil, other other types of vegetation b. What kind and amount of vegetation will be removed or altered? The existing screening arborvitae trees along the east and south sides of the substation will be removed. c. List threatened or endangered species known to be on or near the site. No threatened or endangered plant species are reported on the Washington Department of Fish and Wildlife's Priority Habitats and Species database. None were observed by Wetland Resources, Inc. staff during site visits. d. Proposed landscaping, use of native plants, or other measures to preserve or enhance vegetation on the site, if any: The area outside the south side of the new substation security fence will be landscaped with a variety of native and Pacific Northwest adapted trees, shrubs and plants. Snohomish PUD provides routine maintenance to preserve and enhance site landscaping. 5. Animals a. List any birds and other animals which have been observed on or near the site or are known to be on or near the site. Examples include: Birds: hawk, heron, eagle, songbirds, other. Mammals: deer, bear, elk, beaver, other. Fish: bass, salmon, trout, herring, shellfish, other, Songbirds, birds of prey, small mammals, and coho salmon may be anticipated to be present near the site. b. List any threatened or endangered species known to be on or near the site. None. c. Is the site part of a migration route? If so, explain. Puget Sound Flyway. Page 11 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D No. 1 of Snohomish County USE d. Proposed measures to preserve or enhance wildlife, if any: Addition of native plants to the landscaping may attract birds. e. List any invasive animal species known to be on or near the site. None known. 6. EnergV and Natural Resources a. What kinds of energy (electric, natural gas, oil, wood stove, solar) will be used to meet the completed project's energy needs? Describe whether it will be used for heating, manufacturing, etc. Small amounts of electrical energy will be used to operate the equipment and for lighting the substation when needed. b. Would your project affect the potential use of solar energy by adjacent properties? If so, generally describe. No. c. What kinds of energy conservation features are included in the plans of this proposal? List other proposed measures to reduce or control energy impacts, if any: The substation facility will utilize equipment designed to reduce electrical system losses. 7. Environmental Health a. Are there any environmental health hazards, including exposure to toxic chemicals, risk of fire and explosion, spill, or hazardous waste, that could occur as a result of this proposal? If so, describe. Snohomish PUD constructs and operates its electrical system in compliance with all applicable public safety standards. There is a present and future potential electrical hazard if someone were to gain access to the substation by breaching the security fence. The fence is designed and intended to discourage such occurrences and will comply with the requirements of the National Electrical Safety Code (NESC) ANSI C2 and WAC Chapter 296-45. Transformer oil (mineral insulating oil) and battery acid will be located at the substation in quantities covered by the federal Emergency Planning and Community Right-to-Know Act, Section 312. The amounts of oil and battery acid amounts over 500 lbs, for each location are reported annually j to the Washington State Emergency Response Commission, the V Snohomish County Department of Emergency Management, and the local fire jurisdiction, which in this case is the Arlington Fire Department. The site will include six 115kV circuit breakers containing sulfur hexafluoride gas (SF6) which is utilized in sealed equipment and is not released during routine maintenance and operations. SF6 gas has low toxicity, readily mixes with air, and is used in limited quantities. Electric fields and magnetic fields (EMF) are associated with every power delivery system and electrical device. Possible effects upon human health from electric and magnetic fields continue to be investigated, with Page 12 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE emphasis directed primarily at magnetic fields. The Snohomish PUD looks to the research community for guidance and continues to monitor the research for definitive answers concerning EMF and human health. Current research findings are inconclusive. There are no established or known levels of human exposure to power line magnetic fields which have been determined to be harmful. Neither Washington State nor the Federal government regulates exposure to EMF. 1) Describe any known or possible contamination at the site from present or past uses. None known. 2) Describe existing hazardous chemicals/conditions that might affect project development and design. This includes underground hazardous liquid and gas transmission pipelines located within the project area and in the vicinity. None known. 3) Describe any toxic or hazardous chemicals that might be stored, used, or produced during the project's development or construction, or at any time during the operating life of the project. The control enclosure will contain storage for batteries, used for system control and data communication. The batteries typically contain lead and sulfuric acid and will be installed in accordance with the Uniform Fire Code. The eighteen EMVT's and one Station Service Transformer will contain approximately 60 and 80 gallons per unit respectively of mineral insulating oil that serves as an insulating and cooling medium. 4) Describe special emergency services that might be required. No special emergency services are required beyond normal community emergency response for fire, police and emergency medical aid. 5) Proposed measures to reduce or control environmental health hazards, if any: Electrical Facilities: The substation will be surrounded by a security fence with warning signs and locked entry gates to prevent access by unauthorized persons. Electrical protective devices, such as circuit breakers, insulators, and system remote surveillance equipment will be installed to reduce hazards from faults or overloads. Regular inspections and maintenance will be performed, which will help prevent hazardous conditions. A substation grounding system will be installed to protect people within or adjacent to the substation fence from shock in the event of an electrical fault. Oil and Hazardous Material Spills: Substation facilities are designed to contain the release of mineral insulating oil and battery acid during routine operations and emergency conditions. Spill response procedures have been developed in the Snohomish PUD Spill Prevention Control and Countermeasure (SPCC) Plan to address spill situations, as required by federal and state oil use Page 13 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE regulations. The Plan provides for emergency condition notification, site specific response procedures, and utilization of an emergency spill response contractor if initial Snohomish PUD response resources are not sufficient. Oil spill prevention measures include: • Detect oil-filled EMVT and station service transformer failure and/or disrharne thrnnnh rrnrtinr�visual insner_finn and system mnnitnrinn • In the event oil is discharged, initiate the Snohomish PUD Oil Spill Contingency Plan in accordance with 40 CFR Part 109—Criteria for State, Local, and Regional Oil Removal Contingency Plans • Notify authorities, recover, and cleanup an oil discharge in accordance with Washington Administrative Code (WAC), Chapter 173-303— Dangerous Waste Regulations, Section 173-303-145—Spills and Discharges to the Environment. b. Noise: 1) What types of noise exist in the area which may affect your project (for example: traffic, equipment operation, other)? There is traffic noise on 212th ST NE (Tveit Rd) and 87t' Ave NE. Traffic or other noises will not affect the project. 2) What types and levels of noise would be created by or associated with the project on a short-term or a long-term basis (for example: traffic, construction, operation, other)? Indicate what hours noise would come from the site. There will be short-term noise from equipment during construction of the substation for a period of about 9 months. Construction sound levels may intermittently reach 70 dBA at the nearest residential properties. Construction work hours will be limited to the City of Arlington requirements, but are anticipated to occur Monday through Friday from 7:30 a.m. to 5:00 p.m., excluding holidays. There will be occasional minor noise from maintenance vehicles entering and leaving the substation after the substation is in operation. 3) Proposed measures to reduce or control noise impacts, if any: A low noise station service transformer will be utilized in the substation. Based on the results of the acoustical analysis, the noise levels created by the transformer at the substation property lines will be below the 1� permissible limits specified by the current City of Arlington Code (55dBA). 8. Land and Shoreline Use a. What is the current use of the site and adjacent properties?Will the proposal affect current land uses on nearby or adjacent properties? If so, describe. The site is currently used as an electrical substation and zoned Public/ Semi-Public by the City of Arlington. Adjacent to the site's west property line is a 100-ft wide transmission easement containing two 230kV Puget Sound Energy(PSE)transmission lines. Page 14 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE The adjacent property to the north is the Navy's Area 51 electrical substation zoned RHD (High-Density Residential). Adjacent properties to the west of the transmission corridor and north of the Navy's yard are zoned RHD (High-Density Residential). Properties to the east are zoned RLMD(Low to Moderate Density Residential). The adjacent property to the south across 2121" St NE is the Eagle Creek Substation, also zoned Public/Semi Public. The proposal will not affect current land uses on adjacent properties. b. Has the project site been used as working farmlands or working forest lands? If so, describe. How much agricultural or forest land of long-term commercial significance will be converted to other uses as a result of the proposal, if any? If resource lands have not been designated, how many acres in farmland or forest land tax status will be converted to nonfarm or nonforest use? No. 1) Will the proposal affect or be affected by surrounding working farm or forest land normal business operations, such as oversize equipment access, the application of pesticides, tilling, and harvesting? If so, how: No. c. Describe any structures on the site. Two equipment enclosures, dead-end structures, switches, bus supports, circuit breakers, etc. d. Will any structures be demolished? If so, what? Yes, everything inside the existing substation security fence including the fence will be demolished. e. What is the current zoning classification of the site? Public/Semi-Public f. What is the current comprehensive plan designation of the site? Public/Semi-Public g. If applicable, what is the current shoreline master program designation of the site? Not applicable. h. Has any part of the site been classified as a critical area by the city or county? If so, specify. No. i. Approximately how many people would reside or work in the completed project? None. j. Approximately how many people would the completed project displace? None. k. Proposed measures to avoid or reduce displacement impacts, if any: None. Page 15 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE I. Proposed measures to ensure the proposal is compatible with existing and projected land uses and plans, if any: Mitigation of visual impacts through enhanced landscaping. 9. Housing a. Approximately how many units would be provided, if any? Indicate whether high, middle, or low-income housing. None. b. Approximately how many units, if any would be eliminated? Indicate whether high, middle, or low-income housing. None. c. Proposed measures to reduce or control housing impacts, if any: None. 10. Aesthetics a. What is the tallest height of any proposed structure(s), not including antennas; what is the principal exterior building material(s) proposed? There are no buildings proposed. Approximate transmission pole and substation structure/equipment heights: Three Temporary Wood Transmission Poles 60 ft Six Transmission Line Termination (Dead-End) Structures 40 ft High Bus and Support Structures 25 ft Low Bus and Support Structures 18 ft Equipment Enclosure 13 ft b What views in the immediate vicinity would be altered or obstructed? Similar to existing conditions. c. Proposed measures to reduce or control aesthetic impacts, if any: Landscaping will be added to the south and potentially east side of the substation site. 11. Light and Glare a. What type of light or glare will the proposal produce?What time of day would it mainly occur? Interior security and emergency lighting will be installed inside the substation and will normally be used only if needed during nighttime emergency repair work. b. Could light or glare from the finished project be a safety hazard or interfere with views? No. Page 16 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE c. What existing off-site sources of light or glare may affect your proposal? None. d. Proposed measures to reduce or control light and glare impacts, if any: Lighting identified in paragraph (a) above will be directed inward, toward equipment being worked on during nighttime emergency repair work. Any security lighting will be motion activated to minimize illumination time. 12. Recreation a. What designated and informal recreational opportunities are in the immediate vicinity? None. b. Would the proposed project displace any existing recreational uses? If so, describe. No. c. Proposed measures to reduce or control impacts on recreation, including recreation opportunities to be provided by the project or applicant, if any: None. 13. Historic and Cultural Preservation a. Are there any buildings, structures, or sites, located on or near the site that are over 45 years old listed in or eligible for listing in national, state, or local preservation registers located on or near the site? If so, specifically describe. None known. b. Are there any landmarks, features, or other evidence of Indian or historic use or occupation?This may include human burials or old cemeteries. Are there any material evidence, artifacts, or areas of cultural importance on or near the site? Please list any professional studies conducted at the site to identify such resources. None known. c. Describe the methods used to assess the potential impacts to cultural and historic resources on or near the project site. Examples include consultation with tribes and the department of archeology and historic preservation, archaeological surveys, historic maps, GIS data, etc. An addendum to the Cultural Resources Assessment Report for the Eagle Creek Substation Project was completed on May 30, 2017 to assess the potential cultural and historic resources on or near the East Arlington Substation Project site. If any artifacts, historical or cultural features are uncovered during site / clearing and excavation, work will be immediately stopped and contact made with appropriate staff at the City of Arlington and the Washington State Department of Archaeology & Historic Preservation. All protocols outlined in the Monitoring and Inadvertent Discovery Plan (MIDP) for the Eagle Creek project (Steinkraus 2017) will be applied. Page 17 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE d. Proposed measures to avoid, minimize, or compensate for loss, changes to, and disturbance to resources. Please include plans for the above and any permits that may be required. None. 14. Transportation a. Identify public streets and highways serving the site, and describe proposed access to the existing street system. Show on site pians, if any. 212th St NE (Tveit Rd) is the southern frontage and 87t" Ave NE is the eastern frontage of the substation site. The main access to and from the substation will be directly from 212th St NE. b. Is the site or affected geographic area currently served by public transit? If so, generally describe. If not, what is the approximate distance to the nearest transit stop? Not applicable. c. How many parking spaces would the completed project have? How many would the project eliminate? One parking space outside the security fence will be provided for maintenance vehicles. d. Will the proposal require any new or improvements to existing roads, streets, pedestrian, bicycle or state transportation facilities, not including driveways? If so, generally describe (indicate whether public or private). No. e. Will the project use (or occur in the immediate vicinity of) water, rail, or air transportation? If so, generally describe. No. f. How many vehicular trips per day would be generated by the completed project? If known, indicate when peak volumes would occur. Trips per day will be less than one per day, on the average. g. Proposed measures to reduce or control transportation impacts, if any: None. 15. Public Services a. Would the project result in an increased need for public services (for example: fire protection, police protection, health care, schools, other)? If so, generally describe. No. b. Proposed measures to reduce or control direct impacts on public services, if any. None. Page 18 of 19 SEPA ENVIRONMENTAL CHECKLIST FOR East Arlington Substation AGENCY P.U.D. No. 1 of Snohomish County USE 16. Utilities a. Underline utilities currently available at the site: electricity, natural gas, water, refuse service, telephone, sanitary sewer, septic system, storm sewer, cable TV. b. Describe the utilities that are proposed for the project,the utility providing the service, and the general construction activities on the site or in the immediate vicinity which might be needed. Power: Snohomish PUD Telephone: Snohomish PUD fiber system Water: City of Arlington (landscape irrigation) C. SIGNATURE The above answers are true and complete to the best of my knowledge. I understand that the lead agency is relying on them to make its decision. Signature: ✓1wn Name of signee: o v+n e� J i GLC S Position and Agency/Organization: Date Submitted: 2 7 2 o I B i Page 19of19 i Stormwater Pollution Prevention Plan For East Arlington Switching Station Owner Snohomish County PUD No. 1 P.O. Box 1107 Everett, WA, 98206-1107 Project Site Location 21210 87`h Ave NE Arlington, WA 98203 SWPPP Prepared By Snohomish County PUD No. 1 P.O. Box 1107 Everett, WA (425)-783-5022 Tom Hendricks, PE SWPPP Preparation Date 5/16/2018 Approximate Project Construction Dates July 2018 Through November 2018 4� A� D 3M Contents 1.0 Introduction 1 2.0 Site Description 3 2.1 Existing Conditions 3 2.2 Proposed Construction Activities 4 3.0 Construction Stormwater BMPs 6 3.1 The 12 BMP Elements 6 3.1.1 Element#1 —Mark Clearing Limits 6 3.1.2 Element#2—Establish Construction Access 6 3.1.3 Element#3 —Control Flow Rates 7 3.1.4 Element#4—Install Sediment Controls 7 3.1.5 Element#5 —Stabilize Soils 8 3.1.6 Element#6—Protect Slopes 9 3.1.7 Element#7—Protect Drain Inlets 9 3.1.8 Element#8—Stabilize Channels and Outlets 10 3.1.9 Element#9—Control Pollutants 10 3.1.10 Element#10—Control Dewatering 11 3.1.11 Element#11 —Maintain BMPs 12 3.1.12 Element#12—Manage the Project 12 3.2 Site Specific BMPs 14 4.0 Construction Phasing and BMP Implementation 15 5.0 Pollution Prevention Team 16 5.1 Roles and Responsibilities 16 5.2 Team Members 16 6.0 Site Inspections and Monitoring 17 6.1 Site Inspection 17 6.1.1 Site Inspection Frequency 17 6.1.2 Site Inspection Documentation 17 6.2 Stormwater Quality Monitoring 18 6.2.1 Turbidity 18 6.2.2 pH Sampling 19 7.0 Reporting and Recordkeeping 20 7.1 Recordkeeping 20 7.1.1 Site Log Book 20 7.1.2 Records Retention 20 7.1.3 Access to Plans and Records 20 ii 7.1.4 Updating the SWPPP 20 7.2 Reporting 21 7.2.1 Discharge Monitoring Reports 21 7.2.2 Notification of Noncompliance 21 7.2.3 Permit Application and Changes 21 Appendix A Site plans—Refer to Contract Drawings Appendix B Construction BMPs Appendix C Alternative Construction BMP list Appendix D General Permit Appendix E Site Log and Inspection Forms iii Stormwater Pollution Prevention Plan 1.0 Introduction This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the NPDES stormwater permit requirements for the East Arlington Switching Station project located at 21210 87th Ave NE, Arlington. The existing substation property lies to the northwest of the intersection of 212th St NE and 87th Ave NE. The construction site is a 1.25-acre portion of a 1.66 acre parcel that currently contains the East Arlington Substation. The proposed development consists of the removal of the existing out dated 115kV and 12kV substation and replacement with a new six-breaker ring bus 115kV switching station. Construction activities will include installing TESC measures, demolition of the existing substation improvements, excavation, grading, installation of drainage features, construction of foundations and slabs for the new equipment, installation of underground conduit and vaults, constructing a grounding system, installing a new security fence with high voltage warning signs, one paved main driveway and four maintenance access gravel driveways, landscaping, and an irrigation system. The purpose of this SWPPP is to describe the proposed construction activities and all temporary and permanent erosion and sediment control (TESC) measures, pollution prevention measures, and inspection activities that will be implemented during the proposed construction project. The objectives of the SWPPP are to: 1. Implement Best Management Practices (BMPs) to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. Prevent violations of surface water quality, ground water quality, or sediment management standards. 3. Prevent, during the construction phase, adverse water quality impacts including impacts on beneficial uses of the receiving water by controlling peak flow rates and volumes of stormwater runoff at the Permittee's outfalls and downstream of the outfalls. This SWPPP was prepared using the Ecology SWPPP Template downloaded from the Ecology website on March 29, 2018. This SWPPP was prepared based on the requirements set forth in the Construction Stormwater General Permit,Stormwater Management Manual for Western Washington (SWMMWW 2012/14). The report is divided into seven main sections with several appendices that include stormwater related reference materials. The topics presented in each of the main sections are: ■ Section 1— INTRODUCTION. This section provides a summary description of the project, and the organization of the SWPPP document. 1 Stormwater Pollution Prevention Plan ■ Section 2—SITE DESCRIPTION. This section provides a detailed description of the existing site conditions, proposed construction activities, and calculated stormwater flow rates for existing conditions and post—construction conditions. ■ Section 3—CONSTRUCTION BMPs. This section provides a detailed description of the BMPs to be implemented based on the 12 required elements of the SWPPP. ■ Section 4—CONSTRUCTION PHASING AND BMP IMPLEMENTATION. This section provides a description of the timing of the BMP implementation in relation to the project schedule. ■ Section 5— POLLUTION PREVENTION TEAM. This section identifies the appropriate contact names (emergency and non-emergency), monitoring personnel, and the onsite temporary erosion and sedimentation control inspector ■ Section 6— INSPECTION AND MONITORING. This section provides a description of the inspection and monitoring requirements such as the parameters of concern to be monitored, sample locations, sample frequencies, and sampling methods for all stormwater discharge locations from the site. ■ Section 7— RECORDKEEPING. This section describes the requirements for documentation of the BMP implementation, site inspections, monitoring results, and changes to the implementation of certain BMPs due to site factors experienced during construction. 2 Stormwater Pollution Prevention Plan 2.0 Site Description 2.1 Existing Conditions The existing substation site is located 21210 87th Avenue NE in the City of Arlington, WA 98223. Eagle Creek lies to the east with buffers that extend onto the site. The existing substation site is generally flat with any upstream runoff bypassing the site in a grass-lined swale to the west of the existing substation fence and flowing into an 18-inch CMP near the southwest substation fence corner that turns eastward and extends along the north side of 2121h St NE to a city catch basin at the intersection of 212th St NE and 87th Ave NE eventually discharging into Eagle Creek. Currently any stormwater inside the substation yard that doesn't infiltrate into the substation gravel and native subgrade is gathered in perforated pipe underneath the cable trench and is collected in an oil separator basin near the southeast corner of the site, which discharges through an oil trap to the previously mentioned city catch basin at the intersection of 212th St NE and 87th Ave NE. The eastern 75% of the property contains the developed electrical substation site and the western 25% is covered with native shrubs and emergent species. Along the south and east substation security fence a single row of arborvitae trees exists for visual screening purposes. Grades in the existing substation yard generally descend from northwest to southeast with the local high elevation of 162 feet in a small area of the northwest corner of the existing yard and the low of 156 feet in the southeast corner of the property outside the fence. Three wetlands exist in fairly close proximity with buffers that extend onto the substation site. Refer to The Critical Area Determination Report for Snohomish County PUD No. 1 East Arlington and Eagle Creek Substations prepared by Wetland Resources, Inc. dated July 2016 and revised on January 25, 2017 Zipper Geo Associates, LLC has prepared a geotechnical report for the site titled Geotechnical Engineering Report, Proposed Eagle Creek Substation dated September 15, 2016. With the exception of the northwest corner, the entire yard is surfaced with coarse gravel-size crushed rock. Surfacing in the northwest corner consists of gravelly sand and quarry spalls. The thickness of the fill varied across the yard from about 2 feet to 7.5 feet in depth with characteristics varying from medium dense silty gravel to medium dense to very dense gravelly sand. Native soils observed below the surficial fill material generally consisted of medium dense to very dense silty sand with variable gravel content. The US Department of Agriculture's Soil Survey of Snohomish County Area Washington has the on-site soils mapped mostly as Everett very b gravelly sandy loam, with 0 to 8 percent slopes. The 2016 geotechnical report states the Geologic Map of the Arlington East Quadrangle, Snohomish County, Washington describes the site as underlain by the Marysville Sand member of recessional outwash deposits. However, based upon the condition disclosed by the boring completed on the site, it appears that the native soils are more representative of the glacial till which has been mapped to the southeast and northwest of the site and underlies the recessional deposits. 3 Stormwater Pollution Prevention Plan 2.2 Proposed Construction Activities This project involves the demolition of the existing PUD East Arlington Substation and the reconstruction of a new six breaker 115 kV ring bus switching station. The entire existing substation site will be redeveloped with new foundations and equipment including a new fence with enhanced maintenance access from 212th St NE and from 87th Ave NE. Construction activities will include installing TESC measures; demolition of existing concrete foundations & slabs, conduit& conductor, cable trench, grounding system, and security fence except the common fence with the Navy's Area 51 yard. Removal of unsuitable soils; regrading the site and excavation of trenches and foundations; installing new conduit, foundations, slabs, a stormwater interceptor trench, electrical vaults, security fence, and gravel & asphalt driveways. Upstream runoff currently bypasses the substation site in a grass-lined swale to the west of the existing substation fence and enters an 18" CMP near the southwest substation fence corner that turns and extends eastward along the north side of 212th St NE to a city catch basin at the intersection with 87th Ave NE which discharges eastward through a 12 inch CPP into Eagle Creek. This existing bypass condition is outside the proposed construction area and will remain unchanged after the proposed development. For the substation redevelopment the site runoff is intended to be infiltrated through the substation gravel or into the landscaping areas. Precipitation falling within the substation yard will infiltrate through the imported crushed rock fill layer and then at a relatively slower rate will infiltrate into the native soil below. The imported crushed rock base and interceptor trench will act as a reservoir, retaining water during intense rainfall events. Water runoff from landscaped areas will drain naturally. The following summarizes details regarding site areas: • Total existing developed substation area: 1.25 acres • Percent impervious area before construction: 23.67% • Percent impervious area after construction: 8.07% • Disturbed area during construction: 1.25 acres • Disturbed area that is characterized as impervious (i.e., access roads, staging,parking): 0.2959 acres • 2-year stormwater runoff peak flow prior to construction(existing): 0.181 cfs • 10-year stormwater runoff peak flow prior to construction(existing): 0.324 cfs • 2-year stormwater runoff peak flow during construction: 0.025 cfs • 10-year stormwater runoff peak flow during construction: 0.045 cfs • 2-year stormwater runoff peak flow after construction: 0.025 cfs • 10-year stormwater runoff peak flow after construction: 0.045 cfs 4 Stormwater Pollution Prevention Plan Peak flow values were calculated using the WWHM12 software. Refer to the Full Drainage Report for the calculations. No temporary/permanent TESC or flow control BMP's are proposed that require flow rate based engineering calculation. After the imported substation gravel in the substation yard and gravel perimeter is graded to final top of rock elevation, the gravel driveways are graded to final elevation, and the asphalt pavement for the main driveway is placed; the landscaping and irrigation system will be installed to stabilize the site. Should any unexpected contaminated soils be uncovered the District's Environmental Affairs department will be contacted and proper cleanup measures will be implemented. Any ground water encountered will be dealt with appropriately and the method will be selected by the site contractor. The method could be pumping the groundwater into a Baker tank and either hauling contaminated water to an offsite disposal site or metering the uncontaminated discharge into existing native vegetation and grassy areas onsite. 5 Stormwater Pollution Prevention Plan 3.0 Construction Stormwater BMPs 3.1 The 12 BMP Elements 3.1.1 Element#1 —Mark Clearing Limits To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. Trees that are to be preserved, as well as all sensitive areas and their buffers, shall be clearly delineated,both in the field and on the plans. In general, natural vegetation and native topsoil shall be retained in an undisturbed state to the maximum extent possible. The BMPs relevant to marking the clearing limits that will be applied for this project include: • Preserving Natural Vegetation (BMP C 101) • High Visibility Plastic or Metal Fence (BMP C 103) High visibility fence will be staked along property lines where property line fencing does not exist as well as around vegetated areas to be preserved. Preserved areas will provide stormwater filtration, and reduce runoff velocity. Alternate BMPs for marking clearing limits are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.2 Element#2—Establish Construction Access Construction access or activities occurring on unpaved areas shall be minimized, yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads, and wheel washing, street sweeping, and street cleaning shall be employed to prevent sediment from entering state waters. All wash wastewater shall be controlled on site. The specific BMPs related to establishing construction access that will be used on this project include: • Stabilized Construction Entrance (BMP C 105) • Construction Road/Parking Area Stabilization(BMP C 107) The existing two gravel driveways will be utilized as the project site's stabilized construction entrances. The existing gravel area in the southeast corner of the property will provide a suitable parking area for construction traffic. A secondary parking area will be north of the existing substation in the gravel area east of the Navy's Area 51 yard. Alternate construction access BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate 6 Stormwater Pollution Prevention Plan during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.3 Element#3—Control Flow Rates In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site shall be controlled. Any stormwater collected will be directed to a collection point along the west side of the construction site and dispersed through a silt bag into the natural vegetation which covers the west 25% of the substation property. Dispersed stormwater will sheet flow over the preserved vegetated areas and surface infiltrate. Flow control will be provided via infiltration and attenuation. The project will ultimately reduce the impervious surface area on-site and enhance the landscaping surface area. An increase in stormwater runoff velocity and peak flow rates are not expected as a result of the proposed construction activity. Dispersion and infiltration BMP's shall be used to contain stormwater on-site. Alternate flow control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. In general, discharge rates of stormwater from the site will be controlled where increases in impervious area or soil compaction during construction could lead to downstream erosion, or where necessary to meet local agency stormwater discharge requirements (e.g. discharge to combined sewer systems). 3.1.4 Element#4—Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharged to an infiltration facility. The specific BMPs to be used for controlling sediment on this project include: • Storm Drain Inlet Protection(BMP C220) • Silt Fence (BMP C233) • Straw Wattles (BMP C235) 7 Stormwater Pollution Prevention Plan The preserved natural vegetation to the west of the disturbance will provide stormwater filtration, and reduce any runoff velocity. Storm drain inlet protection will be installed in all proposed catch basins susceptible to sediment loading. Silt fencing will be installed along the west side of the construction area to prevent any sediment laden water from discharging into the grassy swale along the west side that directs any flow to the 18-inch CMP. Straw wattles would be an alternate sediment control BMP placed in the grassy swale to control any potential flow in the grassy swale. Alternate sediment control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. In addition, sediment will be removed from paved areas in and adjacent to construction work areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on vehicle tires away from the site and to minimize wash off of sediments from adjacent streets in runoff. In some cases, sediment discharge in concentrated runoff can be controlled using permanent stormwater BMPs (e.g., infiltration swales, ponds, trenches). Sediment loads can limit the effectiveness of some permanent stormwater BMPs, such as those used for infiltration or biofiltration; however, those BMPs designed to remove solids by settling(wet ponds or detention ponds) can be used during the construction phase. When permanent stormwater BMPs will be used to control sediment discharge during construction, the structure will be protected from excessive sedimentation with adequate erosion and sediment control BMPs. Any accumulated sediment shall be removed after construction is complete and the permanent stormwater BMP will be restabilized with vegetation per applicable design requirements once the remainder of the site has been stabilized. 3.1.5 Element#5—Stabilize Soils Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. The specific BMPs for soil stabilization that shall be used on this project include: • Temporary and Permanent Seeding(BMP C 120) • Plastic Covering(BMP C123) • Topsoiling(BMP C 125) • Surface Roughening (BMP C130) • Dust Control (BMP C 140) • Early application of gravel base on areas to be graveled. 8 Stormwater Pollution Prevention Plan Alternate soil stabilization BMPs are included in Appendix C as a quick reference tool for the on-site inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction. The Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, no soils shall remain exposed and unworked for more than 7 days during the dry season(May 1 to September 30) and 2 days during the wet season(October 1 to April 30). Regardless of the time of year, all soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on weather forecasts. In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion, protected with sediment trapping measures, and where possible,be located away from storm drain inlets, waterways, and drainage channels. 3.1.6 Element#6—Protect Slopes All cut and fill slopes will be designed, constructed, and protected in a manner that minimizes erosion. The following specific BMPs will be used to protect slopes for this project: • Temporary and Permanent Seeding(BMP C 120) • Straw Wattle (BMP C235) Alternate slope protection BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.7 Element#7—Protect Drain Inlets Two storm drain inlets exist near the site that could potentially receive surface runoff from the construction site. One is at the corner of 2121h St NE and 87th Ave NE and the other is approximately 240 feet west along the north side of 212th St NE. Also the 18" CMP inlet near the southwest fence corner could potentially receive surface runoff from the construction site since the grassy swale along the west side of the construction site flows directly into this culvert. The grassy swale should be dry during the timeframe of this construction,but a rain event could change these dry conditions and create flow that would enter the culvert and City's storm water drainage system. All storm drain inlets and culverts made operable during construction shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. However, the first priority is to keep all access roads clean of sediment and keep street wash water separate 9 Stormwater Pollution Prevention Plan from entering storm drains until treatment can be provided. Storm Drain Inlet Protection(BMP C220)will be implemented for all drainage inlets and culverts that could potentially be impacted by sediment-laden runoff on and near the project site. The following inlet protection measures will be applied on this project: • Storm Drain Inlet Protection(BMP C220) If the BMP options listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D), or if no BMPs are listed above but deemed necessary during construction, the Certified Erosion and Sediment Control Lead shall implement one or more of the alternative BMP inlet protection options listed in Appendix C. 3.1.8 Element#8—Stabilize Channels and Outlets Where site runoff is to be conveyed in channels efforts will be taken to prevent downstream erosion. The specific BMPs for channel and outlet stabilization that shall be used on this project include: • Grass-Lined Swales (BMP C201) • Outlet Protection (BMP C209) There are no channels or direct discharge to a stream for this project. A natural grass swale does exist west of the construction area. This grassy swale shall be utilized to intercept any surface water runoff that may flow out of the natural vegetation area covering the west 25% of the of the substation property as a result of dewatering the construction site. The outlet of any pipe discharge shall be protected to prevent scouring and downstream erosion. Alternate channel and outlet stabilization BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.9 Element#9—Control Pollutants All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well-organized, and free of debris. If required, BMPs to be implemented to control specific sources of pollutants are discussed below. 10 Stormwater Pollution Prevention Plan Vehicles, construction equipment, and/or petroleum product storage/dispensing: ■ All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. ■ On-site fueling tanks and petroleum product storage containers shall include secondary containment. ■ Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. ■ In order to perform emergency repairs on site, temporary plastic will be placed beneath and, if raining, over the vehicle. ■ Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Chemical storage: ■ Any chemicals stored in the construction areas will conform to the appropriate source control BMPs listed in Volume IV of the Ecology stormwater manual. In Western WA, all chemicals shall have cover, containment, and protection provided on site,per BMP C 153 for Material Delivery, Storage and Containment. Demolition: ■ Dust released from demolished sidewalks, structures, or foundations will be controlled using Dust Control measures (BMP C 140). ■ Storm drain inlets vulnerable to stormwater discharge carrying dust, soil, or debris will be protected using Storm Drain Inlet Protection (BMP C 152) ■ Process water and slurry resulting from sawcutting and surfacing operations will be prevented from entering the waters of the State by implementing Sawcutting and Surfacing Pollution Prevention measures (BMP C 152). Concrete and grout: ■ Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures (BMP C 151). Ultimately, a Spill Prevention, Control, and Countermeasure (SPCC) Plan under the Federal regulations of the Clean Water Act(CWA) will be required for the substation once operational. 3.1.10 Element#10—Control Dewatering All dewatering water from open cut excavation, tunneling, foundation work, trench, or underground vaults shall be discharged into a controlled conveyance system prior to discharge to 11 Stormwater Pollution Prevention Plan a sediment trap or sediment pond. Any channels will be stabilized, per Element#8. Clean, non- turbid dewatering water will not be routed through stormwater sediment ponds, and will be discharged to systems tributary to the receiving waters of the State in a manner that does not cause erosion, flooding, or a violation of State water quality standards in the receiving water. Highly turbid dewatering water from soils known or suspected to be contaminated, or from use of construction equipment, will require additional monitoring and treatment as required for the specific pollutants based on the receiving waters into which the discharge is occurring. Such monitoring is the responsibility of the contractor. However, the dewatering of soils known to be free of contamination will trigger BMPs to trap sediment and reduce turbidity. At a minimum, geotextile fabric socks/bags/cells will be used to filter this material. Other BMPs to be used for sediment trapping and turbidity reduction include the following: • Concrete Handling(BMP C151) • Use of a sedimentation bag, with outfall to vegetated area for small volumes of localized dewatering. 3.1.11 Element#11 —Maintain BMPs All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMPs specifications. Visual monitoring of the BMPs will be conducted at least once every calendar week and within 24 hours of any rainfall event that causes a discharge from the site. If the site becomes inactive, and is temporarily stabilized, the inspection frequency will be reduced to once every month. All temporary erosion and sediment control BMPs shall be removed within 30 days after the final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil resulting from removal of BMPs or vegetation shall be permanently stabilized. 3.1.12 Element#12—Manage the Project Erosion and sediment control BMPs for this project have been designed based on the following principles: ■ Design the project to fit the existing topography, soils, and drainage patterns. ■ Emphasize erosion control rather than sediment control. ■ Minimize the extent and duration of the area exposed. ■ Keep runoff velocities low. ■ Retain sediment on site. ■ Thoroughly monitor site and maintain all ESC measures. ■ Schedule major earthwork during the dry season. 12 Stormwater Pollution Prevention Plan In addition,project management will incorporate the key components listed below: As this project site is located west of the Cascade Mountain Crest, the project will be managed according to the following key project components: Phasing of Construction ■ The construction project is being phased to the extent practicable in order to prevent soil erosion, and, to the maximum extent possible, the transport of sediment from the site during construction. ■ Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of the clearing activities during each phase of construction, per the Scheduling BMP (C162). Seasonal Work Limitations ■ From October 1 through April 30, clearing, grading, and other soil disturbing activities shall only be permitted if shown to the satisfaction of the local permitting authority that silt-laden runoff will be prevented from leaving the site through a combination of the following: ❑ Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters; and ❑ Limitations on activities and the extent of disturbed areas; and ❑ Proposed erosion and sediment control measures. ■ Based on the information provided and/or local weather conditions, the local permitting authority may expand or restrict the seasonal limitation on site disturbance. ■ The following activities are exempt from the seasonal clearing and grading limitations: ❑ Routine maintenance and necessary repair of erosion and sediment control BMPs; ❑ Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil; and ❑ Activities where there is 100 percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. Coordination with Utilities and Other Jurisdictions ■ Care has been taken to coordinate with utilities, other construction projects, and the local jurisdiction in preparing this SWPPP and scheduling the construction work. 13 Stormwater Pollution Prevention Plan Inspection and Monitoring ■ All BMPs shall be inspected, maintained, and repaired as needed to assure continued performance of their intended function. Site inspections shall be conducted by a person who is knowledgeable in the principles and practices of erosion and sediment control. This person has the necessary skills to: ❑ Assess the site conditions and construction activities that could impact the quality of stormwater, and ❑ Assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. ■ A Certified Erosion and Sediment Control Lead shall be on-site or on-call at all times. ■ Whenever inspection and/or monitoring reveals that the BMPs identified in this SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP ■ This SWPPP shall be retained on-site or within reasonable access to the site. ■ The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. ■ The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven (7) days following the inspection. 3.2 Site Specific BMPs Site specific BMPs are shown on the TESC Plan Sheets and Details in Appendix A. These site specific plan sheets will be updated annually. 14 Stormwater Pollution Prevention Plan 4.0 Construction Phasing and BMP Implementation The BMP implementation schedule will be driven by the construction schedule. The following provides a sequential list of the proposed construction schedule milestones and the corresponding BMP implementation schedule. The list contains key milestones such as wet season construction. The BMP implementation schedule listed below is keyed to proposed phases of the construction project, and reflects differences in BMP installations and inspections that relate to wet season construction. The project site is located west of the Cascade Mountain Crest. As such, the dry season is considered to be from May 1 to September 30 and the wet season is considered to be from October 1 to April 30. ■ Estimate of Construction start date: 07/16/18 ■ Estimate of Construction finish date: 11/09/18 ■ Mobilize equipment on site: 07/16/18 ■ Mobilize and store all ESC and soil stabilization products (store materials on hand BMP C150): 07/17/18 ■ Mark the limits of site disturbance: 07/17/18 ■ Install silt fencing and storm drain inlet protection: 07/17/18 ■ Start demolition phase: 07/18/18 ■ Start site grading & excavation: 07/30/18 ■ Install interceptor trench and CB's: 08/06/18 ■ Site inspections and monitoring conducted weekly and for applicable rain events as detailed in Section 6 of this SWPPP: 08/06/18 ■ Implement soil stabilization and sediment control BMPs during earthwork activities: 08/06/18 ■ Start grounding well installation: 08/06/18 ■ Start drilled pier installation: 08/13/18 ■ Begin conduit, vaults, and foundation installation: 08/20/18 ■ Wet Season starts: 10/01/18 ■ Start Installation of irrigation and landscaping: 10/01/18 ■ Complete site work: 11/08/18 ■ Remove remaining TESC facilities 11/09/18 ■ Construction Complete 11/09/18 15 Stormwater Pollution Prevention Plan 5.0 Pollution Prevention Team 5.1 Roles and Responsibilities The pollution prevention team consists of personnel responsible for implementation of the SWPPP, including the following: ■ Certified Erosion and Sediment Control Lead(CESCL)—primary contractor contact, responsible for site inspections (BMPs, visual monitoring, sampling, etc.); to be called upon in case of failure of any ESC measures. ■ Resident Engineer—For projects with engineered structures only (sediment ponds/traps, sand filters, etc.): site representative for the owner that is the project's supervising engineer responsible for inspections and issuing instructions and drawings to the contractor's site supervisor or representative. ■ Emergency Ecology Contact—individual to be contacted at Ecology in case of emergency. ■ Emergency Owner Contact—individual that is the site owner or representative of the site owner to be contacted in the case of an emergency. ■ Non-Emergency Ecology Contact—individual that is the site owner or representative of the site owner than can be contacted if required. ■ Monitoring Personnel—personnel responsible for conducting water quality monitoring; for most sites this person is also the Certified Erosion and Sediment Control Lead. 5.2 Team Members Names and contact information for those identified as members of the pollution prevention team are provided in the following table. Title Name(s) Phone Number Certified Erosion and Sediment Control Lead Pending Project Bid (CESCL) Resident Engineer Tom Hendricks,PE 425-783-5022 Emergency Ecology Contact Northwest Region 425-649-7000 Emergency Owner Contact Tom Hendricks 425-783-5022 Non-Emergency Ecology Contact Pending Project Bid Monitoring Personnel Pending Project Bid 16 Stormwater Pollution Prevention Plan 6.0 Site Inspections and Monitoring Monitoring includes visual inspection, monitoring for water quality parameters of concern, and documentation of the inspection and monitoring findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: ■ A record of the implementation of the SWPPP and other permit requirements; ■ Site inspections; and, ■ Stormwater quality monitoring. For convenience, the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. This SWPPP may function as the site log book if desired, or the forms may be separated and included in a separate site log book. However, if separated, the site log book but must be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 6.1 Site Inspection All BMPs will be inspected, maintained, and repaired as needed to assure continued performance of their intended function. The inspector will be a Certified Erosion and Sediment Control Lead (CESCL)per BMP C160. The name and contact information for the CESCL is provided in Section 5 of this SWPPP. Site inspection will occur in all areas disturbed by construction activities and at all stormwater discharge points. Stormwater will be examined for the presence of suspended sediment, turbidity, discoloration, and oily sheen. The site inspector will evaluate and document the effectiveness of the installed BMPs and determine if it is necessary to repair or replace any of the BMPs to improve the quality of stormwater discharges. All maintenance and repairs will be documented in the site log book or forms provided in this document. All new BMPs or design changes will be documented in the SWPPP as soon as possible. 6.1.1 Site Inspection Frequency Site inspections will be conducted at least once a week and within 24 hours following any discharge from the site. For temporary stabilization inactive sites, inspection can be reduced to once per month. 6.1.2 Site Inspection Documentation The site inspector will record each site inspection using the site log inspection forms provided in Appendix E. The site inspection log forms may be separated from this SWPPP document,but will be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 17 Stormwater Pollution Prevention Plan 6.2 Stormwater Quality Monitoring 6.2.1 Turbidity Site discharge during construction could drain to the to the city catch basin at the intersection of 212th St NE and 871h Ave NE eventually discharging into Eagle Creek that discharges into the Stillaguamish River. The three sample locations will be: Sample Location A. Stormwater along the gutter of 212th St NE west of the construction site. This location will represent one potential source of upstream background turbidity. Sample Location B Stormwater in the grassy swale north of the construction site. This location will represent a second potential source of upstream background turbidity. Sample Location B. The city catch basin at the intersection of 212th St NE and 87th Ave NE labeled CB I on drawing S-4-05. This sample location represents turbidity downstream of the discharge point. Monitoring requirements for the proposed project will include either turbidity or water transparency sampling to monitor site discharges for water quality compliance with the 2016 Construction Stormwater General Permit(Appendix D). Sampling will be conducted at all discharge points at least once per calendar week. If there is no flow, the attempt to sample will be recorded in the site log book and reported to Ecology in the monthly Discharge Monitoring Report (DMR) as "No Discharge". Turbidity or transparency monitoring will follow the analytical methodologies described in Section S4 of the 2016 Construction Stormwater General Permit (Appendix D). The key benchmark values that require action are 25 NTU for turbidity(equivalent to 32 cm transparency) and 250 NTU for turbidity(equivalent to 6 cm transparency). If the 25 NTU benchmark for turbidity(equivalent to 32 cm transparency) is exceeded, the following steps will be conducted: I. Ensure all BMPs specified in this SWPPP are installed and functioning as intended. 2. Assess whether additional BMPs should be implemented, and document revisions to the SWPPP as necessary. 3. Sample discharge location daily until the analysis results are less than 25 NTU(turbidity) or greater than 32 cm(transparency). If the turbidity is greater than 25 NTU (or transparency is less than 32 cm)but less than 250 NTU(transparency greater than 6 cm) for more than 3 days, additional treatment BMPs will be implemented within 24 hours of the third consecutive sample that exceeded the benchmark value. Additional treatment BMPs to be considered will include, but are not limited to, off-site treatment, infiltration, filtration and chemical treatment. 18 Stormwater Pollution Prevention Plan If the 250 NTU benchmark for turbidity(or less than 6 cm transparency) is exceeded at any time, the following steps will be conducted: 1. Notify Ecology by phone within 24 hours of analysis (see Section 5.0 of this SWPPP for contact information). 2. Continue daily sampling until the turbidity is less than 25 NTU(or transparency is greater than 32 cm). 3. Initiate additional treatment BMPs such as off-site treatment, infiltration, filtration and chemical treatment within 24 hours of the first 250 NTU exceedance. 4. Implement additional treatment BMPs as soon as possible, but within 7 days of the first 250 NTU exceedance. 5. Describe inspection results and remedial actions taken in the site log book and in monthly discharge monitoring reports as described in Section 7.0 of this SWPPP. 6.2.2 pH Sampling 1. The project does not have "Significant concrete work" (i.e., greater than 1000 cubic yards poured concrete over the life of the project). 19 Stormwater Pollution Prevention Plan 7.0 Reporting and Recordkeeping 7.1 Recordkeeping 7.1.1 Site Log Book A site log book will be maintained for all on-site construction activities and will include: ■ A record of the implementation of the SWPPP and other permit requirements; ■ Site inspections; and, ■ Stormwater quality monitoring. For convenience, the inspection form included in this SWPPP includes the required information for the site log book. 7.1.2 Records Retention Records of all monitoring information(site log book, inspection reports/checklists, etc.), this Stormwater Pollution Prevention Plan, and any other documentation of compliance with permit requirements will be retained during the life of the construction project and for a minimum of three years following the termination of permit coverage in accordance with permit condition S5.C. 7.1.3 Access to Plans and Records The SWPPP, General Permit,Notice of Authorization letter, and Site Log Book will be retained on site or within reasonable access to the site and will be made immediately available upon request to Ecology or the local jurisdiction. A copy of this SWPPP will be provided to Ecology within 14 days of receipt of a written request for the SWPPP from Ecology. Any other information requested by Ecology will be submitted within a reasonable time. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with permit condition S5.G. 7.1.4 Updating the SWPPP In accordance with Conditions S3, S4.13, and S9.13.2 of the General Permit, this SWPPP will be modified if the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site or there has been a change in design, construction, operation, or maintenance at the site that has a significant effect on the discharge, or potential for discharge, of pollutants to the waters of the State. The SWPPP will be modified within seven days of determination based on inspection(s)that additional or modified BMPs are necessary to correct problems identified, and an updated timeline for BMP implementation will be prepared. 20 Stormwater Pollution Prevention Plan 7.2 Reporting 7.2.1 Discharge Monitoring Reports 7.2.2 Notification of Noncompliance If any of the terms and conditions of the permit are not met, and it causes a threat to human health or the environment, the following steps will be taken in accordance with permit section S5.F: l. Ecology will be immediately notified of the failure to comply. 2. Immediate action will be taken to control the noncompliance issue and to correct the problem. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days,unless requested earlier by Ecology. 7.2.3 Permit Application and Changes In accordance with permit condition S2.A, a complete application form will be submitted to Ecology and the appropriate local jurisdiction(if applicable)to be covered by the General Permit. 21 Stormwater Pollution Prevention Plan Appendix A — Site Plans Refer to Contract Drawings 22 Stormwater Pollution Prevention Plan Appendix B — Construction BMPs Preserving Natural Vegetation(BMP C 101) High Visibility Plastic or Metal Fence (BMP C 103) Stabilized Construction Entrance (BMP C 105) Construction Road/Parking Area Stabilization(BMP C107) Temporary and Permanent Seeding(BMP C 120) Plastic Covering(BMP C123) Topsoiling(BMP C125) Surface Roughening (BMP C130) Dust Control (BMP C 140) Materials on Hand (BMP C150) Concrete Handling(BMP C151) Certified Erosion and Sediment Control Lead(BMP C160) Scheduling(BMP C 162) Interceptor Swale (BMP C200) Grass-Lined Swales (BMP C201) Subsurface Drains (BMP C205) Level Spreader(BMP C206) Outlet Protection (BMP C209) Storm Drain Inlet Protection(BMP C220) Silt Fence (BMP C233) Vegetated Strip (BMP C234) Straw Wattle (BMP C235) 23 Table 4.1.1 Source Control BMPs by SWPPP Element V N U N Q U Q ate, 2yIL V) O a E' BMP or Element Name -' E r4 ° Ln i0 00 On `-' m `-' `-' 3 v u xk xz x0 xz xz xz U 0 .� a ., t u .. .. .. .. *' .. c .. .. E C i -11 C VI L C C C N N C C 'gyp C C �"� O' E r6 E �o E E Q E Oo Y E £ '�' > W v N N 0! N O Gl 'Q G1 0 01 7 Gl O T c T c Ol OL N W d � U W Lu U W Ln w Ln W U O W d W G LU G W d BMP C101:Preserving Natural ✓ Vegetation BMP C102:Buffer Zones ✓ ✓ BMP C103:High Visibility Fence ✓ ✓ BMP C105:Stabilized Construction ✓ Entrance/Exit BMP C106:Wheel Wash ✓ BMP C107:Construction Road/Parking ✓ Area Stabilization BMP C120:Temporary and Permanent ✓ ✓ Seeding BMP C121:Mulching ✓ ✓ BMP C122:Nets and Blankets ✓ ✓ ✓ BMP C123:Plastic Covering ✓ ✓ BMP C124:Sodding ✓ ✓ BMP C125:Topsoiling/Composting ✓ BMP C126:Polyacrylamide(PAM)for ✓ Soil Erosion Protection BMP C130:Surface Roughening ✓ ✓ BMP C131:Gradient Terraces ✓ ✓ BMP C140:Dust Control ✓ BMP C150:Materials on Hand ✓ ✓ BMP C151:Concrete Handling ✓ BMP C152:Sawcutting and Surfacing ✓ Pollution Prevention BMP C153:Material Delivery,Storage ✓ and Containment BMP C154:Concrete Washout Area ✓ BMP C160:Certified Erosion and ✓ ✓ Sediment Control Lead BMP C162:Scheduling ✓ Volume II— Construction Stormwater Pollution Prevention -December 2014 4-2 BMP C101: Preserving Natural Vegetation Purpose The purpose of preserving natural vegetation is to reduce erosion wherever practicable. Limiting site disturbance is the single most effective method for reducing erosion. For example, conifers can hold up to about 50 percent of all rain that falls during a storm. Up to 20-30 percent of this rain may never reach the ground but is taken up by the tree or evaporates. Another benefit is that the rain held in the tree can be released slowly to the ground after the storm. Conditions of Use Natural vegetation should be preserved on steep slopes, near perennial and intermittent watercourses or swales, and on building sites in wooded areas. • As required by local governments. • Phase construction to preserve natural vegetation on the project site for as long as possible during the construction period. Design and Natural vegetation can be preserved in natural clumps or as individual Installation trees, shrubs and vines. Specifications The preservation of individual plants is more difficult because heavy equipment is generally used to remove unwanted vegetation. The points to remember when attempting to save individual plants are: • Is the plant worth saving? Consider the location, species, size, age,vigor, and the work involved. Local governments may also have ordinances to save natural vegetation and trees. • Fence or clearly mark areas around trees that are to be saved. It is preferable to keep ground disturbance away from the trees at least as far out as the dripline. Plants need protection from three kinds of injuries: • Construction Equipment- This injury can be above or below the ground level. Damage results from scarring, cutting of roots, and compaction of the soil. Placing a fenced buffer zone around plants to be saved prior to construction can prevent construction equipment injuries. • Grade Changes - Changing the natural ground level will alter grades, which affects the plant's ability to obtain the necessary air, water, and minerals. Minor fills usually do not cause problems although sensitivity between species does vary and should be checked. Trees can typically tolerate fill of 6 inches or less. For shrubs and other plants, the fill should be less. When there are major changes in grade, it may become necessary to supply air to the roots of plants. This can be done by placing a layer of gravel and a tile system over the roots before the fill is made. A tile Volume II—Construction Stormwater Pollution Prevention-December 2014 4-3 system protects a tree from a raised grade. The tile system should be laid out on the original grade leading from a dry well around the tree trunk. The system should then be covered with small stones to allow air to circulate over the root area. Lowering the natural ground level can seriously damage trees and shrubs. The highest percentage of the plant roots are in the upper 12 inches of the soil and cuts of only 2-3 inches can cause serious injury. To protect the roots it may be necessary to terrace the immediate area around the plants to be saved. If roots are exposed, construction of retaining walls may be needed to keep the soil in place. Plants can also be preserved by leaving them on an undisturbed, gently sloping mound. To increase the chances for survival, it is best to limit grade changes and other soil disturbances to areas outside the dripline of the plant. • Excavations -Protect trees and other plants when excavating for drainfields, power, water, and sewer lines. Where possible, the trenches should be routed around trees and large shrubs. When this is not possible, it is best to tunnel under them. This can be done with hand tools or with power augers. If it is not possible to route the trench around plants to be saved, then the following should be observed: Cut as few roots as possible. When you have to cut, cut clean. Paint cut root ends with a wood dressing like asphalt base paint if roots will be exposed for more than 24-hours. Backfill the trench as soon as possible. Tunnel beneath root systems as close to the center of the main trunk to preserve most of the important feeder roots. Some problems that can be encountered with a few specific trees are: • Maple, Dogwood, Red alder, Western hemlock, Western red cedar, and Douglas fir do not readily adjust to changes in environment and special care should be taken to protect these trees. • The windthrow hazard of Pacific silver fir and madrona is high, while that of Western hemlock is moderate. The danger of windthrow increases where dense stands have been thinned. Other species (unless they are on shallow, wet soils less than 20 inches deep) have a low windthrow hazard. • Cottonwoods, maples, and willows have water-seeking roots. These can cause trouble in sewer lines and infiltration fields. On the other hand, they thrive in high moisture conditions that other trees would not. • Thinning operations in pure or mixed stands of Grand fir, Pacific silver fir,Noble fir, Sitka spruce, Western red cedar, Western hemlock, Pacific dogwood, and Red alder can cause serious disease problems. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-4 Disease can become established through damaged limbs, trunks, roots, and freshly cut stumps. Diseased and weakened trees are also susceptible to insect attack. Maintenance Inspect flagged and/or fenced areas regularly to make sure flagging or Standards fencing has not been removed or damaged. If the flagging or fencing has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. • If tree roots have been exposed or injured, "prune" cleanly with an appropriate pruning saw or loppers directly above the damaged roots and recover with native soils. Treatment of sap flowing trees (fir, hemlock,pine, soft maples) is not advised as sap forms a natural healing barrier. BMP C102: Buffer Zones Purpose Creation of an undisturbed area or strip of natural vegetation or an established suitable planting that will provide a living filter to reduce soil erosion and runoff velocities. Conditions of Use Natural buffer zones are used along streams, wetlands and other bodies of water that need protection from erosion and sedimentation. Vegetative buffer zones can be used to protect natural swales and can be incorporated into the natural landscaping of an area. Critical-areas buffer zones should not be used as sediment treatment areas. These areas shall remain completely undisturbed. The local permitting authority may expand the buffer widths temporarily to allow the use of the expanded area for removal of sediment. Design and • Preserving natural vegetation or plantings in clumps,blocks, or strips Installation is generally the easiest and most successful method. Specifications Leave all unstable steep slopes in natural vegetation. • Mark clearing limits and keep all equipment and construction debris out of the natural areas and buffer zones. Steel construction fencing is the most effective method in protecting sensitive areas and buffers. Alternatively, wire-backed silt fence on steel posts is marginally effective. Flagging alone is typically not effective. • Keep all excavations outside the dripline of trees and shrubs. • Do not push debris or extra soil into the buffer zone area because it will cause damage from burying and smothering. • Vegetative buffer zones for streams, lakes or other waterways shall be established by the local permitting authority or other state or federal permits or approvals. Maintenance Inspect the area frequently to make sure flagging remains in place and the Standards area remains undisturbed. Replace all damaged flagging immediately. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-5 BMP C103: High Visibility Fence Purpose Fencing is intended to: l. Restrict clearing to approved limits. 2. Prevent disturbance of sensitive areas, their buffers, and other areas required to be left undisturbed. 3. Limit construction traffic to designated construction entrances, exits, or internal roads. 4. Protect areas where marking with survey tape may not provide adequate protection. Conditions of Use To establish clearing limits plastic, fabric, or metal fence may be used: • At the boundary of sensitive areas, their buffers, and other areas required to be left uncleared. • As necessary to control vehicle access to and on the site. Design and High visibility plastic fence shall be composed of a high-density Installation polyethylene material and shall be at least four feet in height. Posts for Specifications the fencing shall be steel or wood and placed every 6 feet on center (maximum) or as needed to ensure rigidity. The fencing shall be fastened to the post every six inches with a polyethylene tie. On long continuous lengths of fencing, a tension wire or rope shall be used as a top stringer to prevent sagging between posts. The fence color shall be high visibility orange. The fence tensile strength shall be 360 lbs./ft. using the ASTM D4595 testing method. If appropriate install fabric silt fence in accordance with BMP C233 to act as high visibility fence. Silt fence shall be at least 3 feet high and must be highly visible to meet the requirements of this BMP. Metal fences shall be designed and installed according to the manufacturer's specifications. Metal fences shall be at least 3 feet high and must be highly visible. Fences shall not be wired or stapled to trees. Maintenance If the fence has been damaged or visibility reduced, it shall be repaired or Standards replaced immediately and visibility restored. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-6 BMP C105: Stabilized Construction Entrance / Exit Purpose Stabilized Construction entrances are established to reduce the amount of sediment transported onto paved roads by vehicles or equipment. This is done by constructing a stabilized pad of quarry spalls at entrances and exits for construction sites. Conditions of Use Construction entrances shall be stabilized wherever traffic will be entering or leaving a construction site if paved roads or other paved areas are within 1,000 feet of the site. For residential construction provide stabilized construction entrances for each residence, rather than only at the main subdivision entrance. Stabilized surfaces shall be of sufficient length/width to provide vehicle access/parking,based on lot size/configuration. On large commercial, highway, and road projects, the designer should include enough extra materials in the contract to allow for additional stabilized entrances not shown in the initial Construction SWPPP. It is difficult to determine exactly where access to these projects will take place; additional materials will enable the contractor to install them where needed. Design and See Figure 4.1.1 for details. Note: the 100' minimum length of the Installation entrance shall be reduced to the maximum practicable size when the size Specifications or configuration of the site does not allow the full length(100'). Construct stabilized construction entrances with a 12-inch thick pad of 4- inch to 8-inch quarry spalls, a 4-inch course of asphalt treated base (ATB), or use existing pavement. Do not use crushed concrete, cement, or calcium chloride for construction entrance stabilization because these products raise pH levels in stormwater and concrete discharge to surface waters of the State is prohibited. A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into the rock pad. The geotextile shall meet the following standards: Grab Tensile Strength(ASTM D4751) 200 psi min. Grab Tensile Elongation(ASTM 30%max. D4632) Mullen Burst Strength (ASTM 400 psi min. D3786-80a) AOS (ASTM D4751) 20-45 (U.S. standard sieve size) • Consider early installation of the first lift of asphalt in areas that will paved; this can be used as a stabilized entrance. Also consider the installation of excess concrete as a stabilized entrance. During large concrete pours, excess concrete is often available for this purpose. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-7 • Fencing(see BMP C 103) shall be installed as necessary to restrict traffic to the construction entrance. • Whenever possible, the entrance shall be constructed on a firm, compacted subgrade. This can substantially increase the effectiveness of the pad and reduce the need for maintenance. • Construction entrances should avoid crossing existing sidewalks and back of walk drains if at all possible. If a construction entrance must cross a sidewalk or back of walk drain, the full length of the sidewalk and back of walk drain must be covered and protected from sediment leaving the site. Maintenance Quarry spalls shall be added if the pad is no longer in accordance with Standards the specifications. • If the entrance is not preventing sediment from being tracked onto pavement, then alternative measures to keep the streets free of sediment shall be used. This may include replacement/cleaning of the existing quarry spalls, street sweeping, an increase in the dimensions of the entrance, or the installation of a wheel wash. • Any sediment that is tracked onto pavement shall be removed by shoveling or street sweeping. The sediment collected by sweeping shall be removed or stabilized on site. The pavement shall not be cleaned by washing down the street, except when high efficiency sweeping is ineffective and there is a threat to public safety. If it is necessary to wash the streets, the construction of a small sump to contain the wash water shall be considered. The sediment would then be washed into the sump where it can be controlled. • Perform street sweeping by hand or with a high efficiency sweeper. Do not use a non-high efficiency mechanical sweeper because this creates dust and throws soils into storm systems or conveyance ditches. • Any quarry spalls that are loosened from the pad, which end up on the roadway shall be removed immediately. • If vehicles are entering or exiting the site at points other than the construction entrance(s), fencing(see BMP C 103) shall be installed to control traffic. • Upon project completion and site stabilization, all construction accesses intended as permanent access for maintenance shall be permanently stabilized. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-8 Driveway shall meet the requnEments ofthe perniorng agency It is recommended that the entrance be crowned so that mnoffdrams offthe pad A" A'� ]ustall driveway culvert&there is a roadside ditch present 4'—8"auanv malls Geotextae 12"min.thickness f '1 Provide 0 NNidth of in=ss/e=ss area Figure 4.1.1 —Stabilized Construction Entrance Approved as Ecology has approved products as able to meet the requirements of BMP Equivalent C 105. The products did not pass through the Technology Assessment Protocol—Ecology(TAPE)process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at http://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html BMP C106: Wheel Wash Purpose Wheel washes reduce the amount of sediment transported onto paved roads by motor vehicles. Conditions of Use When a stabilized construction entrance (see BMP C 105) is not preventing sediment from being tracked onto pavement. • Wheel washing is generally an effective BMP when installed with careful attention to topography. For example, a wheel wash can be detrimental if installed at the top of a slope abutting a right-of-way where the water from the dripping truck can run unimpeded into the street. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-9 • Pressure washing combined with an adequately sized and surfaced pad with direct drainage to a large 10-foot x I0-foot sump can be very effective. • Discharge wheel wash or tire bath wastewater to a separate on-site treatment system that prevents discharge to surface water, such as closed-loop recirculation or upland land application, or to the sanitary sewer with local sewer district approval. • Wheel wash or tire bath wastewater should not include wastewater from concrete washout areas. Design and Suggested details are shown in Figure 4.1.2. The Local Permitting Installation Authority may allow other designs. A minimum of 6 inches of asphalt Specifications treated base (ATB) over crushed base material or 8 inches over a good subgrade is recommended to pave the wheel wash. Use a low clearance truck to test the wheel wash before paving. Either a belly dump or lowboy will work well to test clearance. Keep the water level from 12 to 14 inches deep to avoid damage to truck hubs and filling the truck tongues with water. Midpoint spray nozzles are only needed in extremely muddy conditions. Wheel wash systems should be designed with a small grade change, 6-to 12-inches for a 10-foot-wide pond, to allow sediment to flow to the low side of pond to help prevent re-suspension of sediment. A drainpipe with a 2-to 3-foot riser should be installed on the low side of the pond to allow for easy cleaning and refilling. Polymers may be used to promote coagulation and flocculation in a closed-loop system. Polyacrylamide (PAM) added to the wheel wash water at a rate of 0.25 - 0.5 pounds per 1,000 gallons of water increases effectiveness and reduces cleanup time. If PAM is already being used for dust or erosion control and is being applied by a water truck, the same truck can be used to change the wash water. Maintenance The wheel wash should start out the day with fresh water. Standards The wash water should be changed a minimum of once per day. On large earthwork jobs where more than 10-20 trucks per hour are expected, the wash water will need to be changed more often. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-10 6" SEWER PIPE WITH 3" TRASH PUMP WITH FLOATS BUTTERFLY VALVES A ON SUCTION HOSE 2" SCHEDULE 40 8'x8' SUMP WITH 5' 1-1/2" SCHEDULE 40 OF CATCH FOR SPRAYERS 2X MIDPOINT SPRAY NOZZLES SLOPE 5:1 f'�?'1 'It I IF NEEDED � SLOPE SLOPE i 2X SLOPE 1.1 6" ATB CONSTRUCTION SLOPE ENTRANCE 15' ATB APRON TO PROTECT A BALL VALVES \ \� GROUND FROM SPLASHING WATER ASPHALT CURB ON THE 6" SLEEVE UNDER ROAD LOW ROAD SIDE TO DIRECT WATER BACK TO POND PLAN VIEW 15' 15' 20' 1 15' 1 50' CURB 6" SLEEVE ELEVATION VIEW LOCATE INVERT OF TOP PIPE 1' ABOVE BOTTOM OF WHEEL WASH 18' 8'x8' SUMP WATER LEVEL -\-,I IR111 3' 5' 12' DRAIN PIPE V1:1 SLOPE SECTION A-A NOTES: 1. BUILD 8'x8' SUMP TO ACCOMODATE CLEANING BY TRACKHOE. Figure 4.1.2 —Wheel Wash Notes: 1. Asphalt construction entrance 6 in. asphalt treated base (ATB). 2. 3-inch trash pump with floats on the suction hose. 3. Midpoint spray nozzles, if needed. 4. 6-inch sewer pipe with butterfly valves. Bottom one is a drain. Locate top pipe's invert 1 foot above bottom of wheel wash. 5. 8 foot x 8 foot sump with 5 feet of catch. Build so the sump can be cleaned with a trackhoe. 6. Asphalt curb on the low road side to direct water back to pond. 7. 6-inch sleeve under road. 8. Ball valves. 9. 15 foot. ATB apron to protect ground from splashing water. Volume II— Construction Stormwater Pollution Prevention -December 2014 4-11 BMP C107: Construction Road/Parking Area Stabilization Purpose Stabilizing subdivision roads, parking areas, and other on-site vehicle transportation routes immediately after grading reduces erosion caused by construction traffic or runoff. Conditions of Use Roads or parking areas shall be stabilized wherever they are constructed, whether permanent or temporary, for use by construction traffic. High Visibility Fencing(see BMP C103) shall be installed, if necessary, to limit the access of vehicles to only those roads and parking areas that are stabilized. Design and • On areas that will receive asphalt as part of the project, install the first Installation lift as soon as possible. Specifications • A 6-inch depth of 2-to 4-inch crushed rock, gravel base, or crushed surfacing base course shall be applied immediately after grading or utility installation. A 4-inch course of asphalt treated base (ATB) may also be used, or the road/parking area may be paved. It may also be possible to use cement or calcium chloride for soil stabilization. If cement or cement kiln dust is used for roadbase stabilization, pH monitoring and BMPs (BMPs C252 and C253) are necessary to evaluate and minimize the effects on stormwater. If the area will not be used for permanent roads,parking areas, or structures, a 6-inch depth of hog fuel may also be used, but this is likely to require more maintenance. Whenever possible, construction roads and parking areas shall be placed on a firm, compacted subgrade. • Temporary road gradients shall not exceed 15 percent. Roadways shall be carefully graded to drain. Drainage ditches shall be provided on each side of the roadway in the case of a crowned section, or on one side in the case of a super-elevated section. Drainage ditches shall be directed to a sediment control BMP. Rather than relying on ditches, it may also be possible to grade the road so that runoff sheet-flows into a heavily vegetated area with a well-developed topsoil. Landscaped areas are not adequate. If this area has at least 50 feet of vegetation that water can flow through, then it is generally preferable to use the vegetation to treat runoff, rather than a sediment pond or trap. The 50 feet shall not include wetlands or their buffers. If runoff is allowed to sheetflow through adjacent vegetated areas, it is vital to design the roadways and parking areas so that no concentrated runoff is created. • Storm drain inlets shall be protected to prevent sediment-laden water entering the storm drain system (see BMP C220). Maintenance Inspect stabilized areas regularly, especially after large storm events. Standards Crushed rock, gravel base, etc., shall be added as required to maintain a Volume II—Construction Stormwater Pollution Prevention-December 2014 4-12 stable driving surface and to stabilize any areas that have eroded. Following construction, these areas shall be restored to pre-construction condition or better to prevent future erosion. Perform street cleaning at the end of each day or more often if necessary. BMP C120: Temporary and Permanent Seeding Purpose Seeding reduces erosion by stabilizing exposed soils. A well-established vegetative cover is one of the most effective methods of reducing erosion. Conditions of Use Use seeding throughout the project on disturbed areas that have reached final grade or that will remain unworked for more than 30 days. The optimum seeding windows for western Washington are April 1 through June 30 and September 1 through October 1. Between July 1 and August 30 seeding requires irrigation until 75 percent grass cover is established. Between October 1 and March 30 seeding requires a cover of mulch with straw or an erosion control blanket until 75 percent grass cover is established. Review all disturbed areas in late August to early September and complete all seeding by the end of September. Otherwise, vegetation will not establish itself enough to provide more than average protection. • Mulch is required at all times for seeding because it protects seeds from heat, moisture loss, and transport due to runoff. Mulch can be applied on top of the seed or simultaneously by hydroseeding. See BMP C 121: Mulching for specifications. • Seed and mulch, all disturbed areas not otherwise vegetated at final site stabilization. Final stabilization means the completion of all soil disturbing activities at the site and the establishment of a permanent vegetative cover, or equivalent permanent stabilization measures (such as pavement, riprap, gabions, or geotextiles)which will prevent erosion. Design and Seed retention/detention ponds as required. Installation Install channels intended for vegetation before starting major Specifications earthwork and hydroseed with a Bonded Fiber Matrix. For vegetated channels that will have high flows, install erosion control blankets over hydroseed. Before allowing water to flow in vegetated channels, establish 75 percent vegetation cover. If vegetated channels cannot be established by seed before water flow; install sod in the channel bottom—over hydromulch and erosion control blankets. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-13 • Confirm the installation of all required surface water control measures to prevent seed from washing away. • Hydroseed applications shall include a minimum of 1,500 pounds per acre of mulch with 3 percent tackifier. See BMP C 121: Mulching for specifications. • Areas that will have seeding only and not landscaping may need compost or meal-based mulch included in the hydroseed in order to establish vegetation. Re-install native topsoil on the disturbed soil surface before application. • When installing seed via hydroseeding operations, only about 1/3 of the seed actually ends up in contact with the soil surface. This reduces the ability to establish a good stand of grass quickly. To overcome this, consider increasing seed quantities by up to 50 percent. • Enhance vegetation establishment by dividing the hydromulch operation into two phases: 1. Phase 1- Install all seed and fertilizer with 25-30 percent mulch and tackifier onto soil in the first lift. 2. Phase 2- Install the rest of the mulch and tackifier over the first lift. Or, enhance vegetation by: 1. Installing the mulch, seed, fertilizer, and tackifier in one lift. 2. Spread or blow straw over the top of the hydromulch at a rate of 800-1000 pounds per acre. 3. Hold straw in place with a standard tackifier. Both of these approaches will increase cost moderately but will greatly improve and enhance vegetative establishment. The increased cost may be offset by the reduced need for: • Irrigation. • Reapplication of mulch. • Repair of failed slope surfaces. This technique works with standard hydromulch(1,500 pounds per acre minimum) and BFM/MBFMs (3,000 pounds per acre minimum). • Seed may be installed by hand if: • Temporary and covered by straw, mulch, or topsoil. • Permanent in small areas (usually less than 1 acre) and covered with mulch, topsoil, or erosion blankets. • The seed mixes listed in the tables below include recommended mixes for both temporary and permanent seeding. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-14 • Apply these mixes, with the exception of the wetland mix, at a rate of 120 pounds per acre. This rate can be reduced if soil amendments or slow-release fertilizers are used. • Consult the local suppliers or the local conservation district for their recommendations because the appropriate mix depends on a variety of factors, including location, exposure, soil type, slope, and expected foot traffic. Alternative seed mixes approved by the local authority may be used. • Other mixes may be appropriate, depending on the soil type and hydrology of the area. • Table 4.1.2 lists the standard mix for areas requiring a temporary vegetative cover. Table 4.1.2 Temporary Erosion Control Seed Mix %Weight %Puri %Germination Chewings or annual blue grass 40 98 90 Festuca rubra var. commutata or Poa anna Perennial rye - 50 98 90 Lolium perenne Redtop or colonial bentgrass 5 92 85 Agrostis alba or Agrostis tenuis White dutch clover 5 98 90 Trifolium repens • Table 4.1.3 lists a recommended mix for landscaping seed. Table 4.1.3 Landscaping Seed Mix %Weight %Puri %Germination Perennial rye blend 70 98 90 Lolium perenne Chewings and red fescue blend 30 98 90 Festuca rubra var. commutata or Festuca rubra Volume II—Construction Stormwater Pollution Prevention -December 2014 4-15 • Table 4.1.4 lists a turf seed mix for dry situations where there is no need for watering. This mix requires very little maintenance. Table 4.1.4 Low-Growing Turf Seed Mix %Wei ht %Puri %Germination Dwarf tall fescue (several varieties) 45 98 90 Festuca arundinacea var. Dwarf perennial rye (Barclay) 30 98 90 Lolium perenne var. Barclay Red fescue 20 98 90 Festuca rubra Colonial bentgrass 5 98 90 Agrostis tenuis • Table 4.1.5 lists a mix for bioswales and other intermittently wet areas. Table 4.1.5 Bioswale Seed Mix* %Wei ht %Puri %Germination Tall or meadow fescue 75-80 98 90 Festuca arundinacea or Festuca elation Seaside/Creeping bentgrass 10-15 92 85 Agrostis palustris Redtop bentgrass 5-10 90 80 Agrostis alba or Agrostis gigantea *Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix Volume II—Construction Stormwater Pollution Prevention -December 2014 4-16 • Table 4.1.6 lists a low-growing, relatively non-invasive seed mix appropriate for very wet areas that are not regulated wetlands. Apply this mixture at a rate of 60 pounds per acre. Consult Hydraulic Permit Authority(HPA) for seed mixes if applicable. Table 4.1.6 Wet Area Seed Mix* %Wei ht %Puri %Germination Tall or meadow fescue 60-70 98 90 Festuca arundinacea or Festuca elation Seaside/Creeping bentgrass 10-15 98 85 Agrostis palustris Meadow foxtail 10-15 90 80 Alepocurus pratensis Alsike clover 1-6 98 90 Trifolium hybridum Redtop bentgrass 1-6 92 85 Agrostis alba *Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix • Table 4.1.7 lists a recommended meadow seed mix for infrequently maintained areas or non-maintained areas where colonization by native plants is desirable. Likely applications include rural road and utility right-of-way. Seeding should take place in September or very early October in order to obtain adequate establishment prior to the winter months. Consider the appropriateness of clover, a fairly invasive species, in the mix. Amending the soil can reduce the need for clover. Table 4.1.7 Meadow Seed Mix %Wei ht %Puri %Germination Redtop or Oregon bentgrass 20 92 85 Agrostis alba or Agrostis oregonensis Red fescue 70 98 90 Festuca rubra White dutch clover 10 98 90 Trifolium repens Volume II—Construction Stormwater Pollution Prevention -December 2014 4-17 • Roughening and Rototilling: • The seedbed should be firm and rough. Roughen all soil no matter what the slope. Track walk slopes before seeding if engineering purposes require compaction. Backblading or smoothing of slopes greater than 4H:1 V is not allowed if they are to be seeded. • Restoration-based landscape practices require deeper incorporation than that provided by a simple single-pass rototilling treatment. Wherever practical, initially rip the subgrade to improve long-term permeability, infiltration, and water inflow qualities. At a minimum,permanent areas shall use soil amendments to achieve organic matter and permeability performance defined in engineered soil/landscape systems. For systems that are deeper than 8 inches complete the rototilling process in multiple lifts, or prepare the engineered soil system per specifications and place to achieve the specified depth. • Fertilizers: • Conducting soil tests to determine the exact type and quantity of fertilizer is recommended. This will prevent the over-application of fertilizer. • Organic matter is the most appropriate form of fertilizer because it provides nutrients (including nitrogen, phosphorus, and potassium) in the least water-soluble form. • In general,use 10-4-6 N-P-K(nitrogen-phosphorus-potassium) fertilizer at a rate of 90 pounds per acre. Always use slow-release fertilizers because they are more efficient and have fewer environmental impacts. Do not add fertilizer to the hydromulch machine, or agitate, more than 20 minutes before use. Too much agitation destroys the slow-release coating. • There are numerous products available that take the place of chemical fertilizers. These include several with seaweed extracts that are beneficial to soil microbes and organisms. If 100 percent cottonseed meal is used as the mulch in hydroseed, chemical fertilizer may not be necessary. Cottonseed meal provides a good source of long-term, slow-release, available nitrogen. • Bonded Fiber Matrix and Mechanically Bonded Fiber Matrix: • On steep slopes use Bonded Fiber Matrix (BFM) or Mechanically Bonded Fiber Matrix (MBFM)products. Apply BFM/MBFM products at a minimum rate of 3,000 pounds per acre of mulch with approximately 10 percent tackifier. Achieve a minimum of 95 percent soil coverage during application. Numerous products are available commercially. Installed products per manufacturer's instructions. Most products require 24-36 hours to cure before rainfall and cannot be installed on wet or saturated soils. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-18 Generally, products come in 40-50 pound bags and include all necessary ingredients except for seed and fertilizer. • BFMs and MBFMs provide good alternatives to blankets in most areas requiring vegetation establishment. Advantages over blankets include: • BFM and MBFMs do not require surface preparation. • Helicopters can assist in installing BFM and MBFMs in remote areas. • On slopes steeper than 2.5H:IV, blanket installers may require ropes and harnesses for safety. • Installing BFM and MBFMs can save at least 51,000 per acre compared to blankets. Maintenance Reseed any seeded areas that fail to establish at least 80 percent cover Standards (100 percent cover for areas that receive sheet or concentrated flows). If reseeding is ineffective, use an alternate method such as sodding, mulching, or nets/blankets. If winter weather prevents adequate grass growth, this time limit may be relaxed at the discretion of the local authority when sensitive areas would otherwise be protected. • Reseed and protect by mulch any areas that experience erosion after achieving adequate cover. Reseed and protect by mulch any eroded area. • Supply seeded areas with adequate moisture, but do not water to the extent that it causes runoff. Approved as Ecology has approved products as able to meet the requirements of BMP Equivalent C120. The products did not pass through the Technology Assessment Protocol—Ecology(TAPE)process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at hM2://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html. BMP C121: Mulching Purpose Mulching soils provides immediate temporary protection from erosion. Mulch also enhances plant establishment by conserving moisture, holding fertilizer, seed, and topsoil in place, and moderating soil temperatures. There is an enormous variety of mulches that can be used. This section discusses only the most common types of mulch. Conditions of Use As a temporary cover measure, mulch should be used: • For less than 30 days on disturbed areas that require cover. • At all times for seeded areas, especially during the wet season and during the hot summer months. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-19 • During the wet season on slopes steeper than 3H:1V with more than 10 feet of vertical relief. Mulch may be applied at any time of the year and must be refreshed periodically. • For seeded areas mulch may be made up of 100 percent: cottonseed meal; fibers made of wood, recycled cellulose, hemp, kenaf; compost; or blends of these. Tackifier shall be plant-based, such as guar or alpha plantago, or chemical-based such as polyacrylamide or polymers. Any mulch or tackifier product used shall be installed per manufacturer's instructions. Generally, mulches come in 40-50 pound bags. Seed and fertilizer are added at time of application. Design and For mulch materials, application rates, and specifications, see Table 4.1.8. Installation Always use a 2-inch minimum mulch thickness; increase the thickness Specifications until the ground is 95% covered(i.e. not visible under the mulch layer). Note: Thickness may be increased for disturbed areas in or near sensitive areas or other areas highly susceptible to erosion. Where the option of"Compost" is selected, it should be a coarse compost that meets the following size gradations when tested in accordance with the U.S. Composting Council "Test Methods for the Examination of Compost and Composting" (TMECC) Test Method 02.02-B. Coarse Compost Minimum Percent passing 3" sieve openings 100% Minimum Percent passing 1" sieve openings 90% Minimum Percent passing 3/4" sieve openings 70% Minimum Percent passing '/4" sieve openings 40% Mulch used within the ordinary high-water mark of surface waters should be selected to minimize potential flotation of organic matter. Composted organic materials have higher specific gravities (densities) than straw, wood, or chipped material. Consult Hydraulic Permit Authority(HPA) for mulch mixes if applicable. Maintenance • The thickness of the cover must be maintained. Standards • Any areas that experience erosion shall be remulched and/or protected with a net or blanket. If the erosion problem is drainage related, then the problem shall be fixed and the eroded area remulched. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-20 Table 4.1.8 Mulch Standards and Guidelines Application Mulch Material Quality Standards Rates Remarks Straw Air-dried;free from 2"-3"thick;5 Cost-effective protection when applied with adequate thickness. undesirable seed and bales per 1,000 Hand-application generally requires greater thickness than coarse material. sf or 2-3 tons per blown straw.The thickness of straw may be reduced by half acre when used in conjunction with seeding.In windy areas straw must be held in place by crimping,using a tackifier,or covering with netting.Blown straw always has to be held in place with a tackifier as even light winds will blow it away. Straw,however, has several deficiencies that should be considered when selecting mulch materials.It often introduces and/or encourages the propagation of weed species and it has no significant long- term benefits.It should also not be used within the ordinary high-water elevation of surface waters(due to flotation). Hydromulch No growth Approx.25-30 Shall be applied with hydromulcher. Shall not be used without inhibiting factors. lbs per 1,000 sf seed and tackifier unless the application rate is at least doubled. or 1,500-2,000 Fibers longer than about 3/4-1 inch clog hydromulch equipment. lbs per acre Fibers should be kept to less than 3/4 inch. Compost No visible water or 2"thick min.; More effective control can be obtained by increasing thickness dust during approx. 100 tons to 3".Excellent mulch for protecting final grades until handling.Must be per acre(approx. landscaping because it can be directly seeded or tilled into soil produced per WAC 800 lbs per yard) as an amendment.Compost used for mulch has a coarser size 173-350,Solid gradation than compost used for BMP C125 or BMP T5.13(see Waste Handling Chapter 5 of Volume V of this manual)It is more stable and Standards,but may practical to use in wet areas and during rainy weather have up to 35% conditions.Do not use near wetlands or near phosphorous biosolids. impaired water bodies. Chipped Site Average size shall 2"thick min.; This is a cost-effective way to dispose of debris from clearing Vegetation be several inches. and grubbing,and it eliminates the problems associated with Gradations from burning.Generally,it should not be used on slopes above fines to 6 inches in approx. 10%because of its tendency to be transported by length for texture, runoff.It is not recommended within 200 feet of surface waters. variation,and If seeding is expected shortly after mulch,the decomposition of interlocking the chipped vegetation may tie up nutrients important to grass properties. establishment. Wood-based No visible water or 2"thick min.; This material is often called"hog or hogged fuel."The use of Mulch or Wood dust during approx. 100 tons mulch ultimately improves the organic matter in the soil. Straw handling.Must be per acre(approx. Special caution is advised regarding the source and composition purchased from a 800 lbs.per of wood-based mulches.Its preparation typically does not supplier with a Solid cubic yard) provide any weed seed control,so evidence of residual Waste Handling vegetation in its composition or known inclusion of weed plants Permit or one or seeds should be monitored and prevented(or minimized). exempt from solid waste regulations. Wood Strand A blend of loose, 2"thick min. Cost-effective protection when applied with adequate thickness. Mulch long,thin wood A minimum of 95-percent of the wood strand shall have lengths pieces derived from between 2 and 10-inches,with a width and thickness between native conifer or 1/16 and%-inches.The mulch shall not contain resin,tannin,or deciduous trees with other compounds in quantities that would be detrimental to plant high length-to-width life. Sawdust or wood shavings shall not be used as mulch. ratio. (WSDOT specification(9-14.4(4)) Volume II—Construction Stormwater Pollution Prevention -December 2014 4-21 BMP C122: Nets and Blankets Purpose Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so that vegetation can become well established. In addition, some nets and blankets can be used to permanently reinforce turf to protect drainage ways during high flows. Nets (commonly called matting) are strands of material woven into an open, but high-tensile strength net(for example, coconut fiber matting). Blankets are strands of material that are not tightly woven,but instead form a layer of interlocking fibers, typically held together by a biodegradable or photodegradable netting (for example, excelsior or straw blankets). They generally have lower tensile strength than nets,but cover the ground more completely. Coir(coconut fiber) fabric comes as both nets and blankets. Conditions of Use Erosion control nets and blankets should be used: • To aid permanent vegetated stabilization of slopes 2H:I V or greater and with more than 10 feet of vertical relief. • For drainage ditches and swales (highly recommended). The application of appropriate netting or blanket to drainage ditches and swales can protect bare soil from channelized runoff while vegetation is established. Nets and blankets also can capture a great deal of sediment due to their open, porous structure. Nets and blankets can be used to permanently stabilize channels and may provide a cost- effective, environmentally preferable alternative to riprap. 100 percent synthetic blankets manufactured for use in ditches may be easily reused as temporary ditch liners. Disadvantages of blankets include: • Surface preparation required. • On slopes steeper than 2.5H:1 V, blanket installers may need to be roped and harnessed for safety. • They cost at least$4,000-6,000 per acre installed. Advantages of blankets include: • Installation without mobilizing special equipment. • Installation by anyone with minimal training • Installation in stages or phases as the project progresses. • Installers can hand place seed and fertilizer as they progress down the slope. • Installation in any weather. • There are numerous types of blankets that can be designed with various parameters in mind. Those parameters include: fiber blend, mesh strength, longevity, biodegradability, cost, and availability. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-22 Design and See Figure 4.1.3 and Figure 4.1.4 for typical orientation and Installation installation of blankets used in channels and as slope protection. Note: Specifications these are typical only; all blankets must be installed per manufacturer's installation instructions. • Installation is critical to the effectiveness of these products. If good ground contact is not achieved, runoff can concentrate under the product, resulting in significant erosion. • Installation of Blankets on Slopes: 1. Complete final grade and track walk up and down the slope. 2. Install hydromulch with seed and fertilizer. 3. Dig a small trench, approximately 12 inches wide by 6 inches deep along the top of the slope. 4. Install the leading edge of the blanket into the small trench and staple approximately every 18 inches. NOTE: Staples are metal, "U"-shaped, and a minimum of 6 inches long. Longer staples are used in sandy soils. Biodegradable stakes are also available. 5. Roll the blanket slowly down the slope as installer walks backwards. NOTE: The blanket rests against the installer's legs. Staples are installed as the blanket is unrolled. It is critical that the proper staple pattern is used for the blanket being installed. The blanket is not to be allowed to roll down the slope on its own as this stretches the blanket making it impossible to maintain soil contact. In addition, no one is allowed to walk on the blanket after it is in place. 6. If the blanket is not long enough to cover the entire slope length, the trailing edge of the upper blanket should overlap the leading edge of the lower blanket and be stapled. On steeper slopes, this overlap should be installed in a small trench, stapled, and covered with soil. • With the variety of products available, it is impossible to cover all the details of appropriate use and installation. Therefore, it is critical that the design engineer consult the manufacturer's information and that a site visit takes place in order to ensure that the product specified is appropriate. Information is also available at the following web sites: 1. WSDOT (Section 3.2.4): http://www.wsdot.wa.gov/NR/rdonl3 res/3B41E087-FA86-4717- 932D-D7A8556CCD57/0/ErosionTraininrManual.pdf 2. Texas Transportation Institute: hqp://www.txdot.gov/business/doing business/product_evaluation/ erosion control.htm Volume II—Construction Stormwater Pollution Prevention -December 2014 4-23 • Use jute matting in conjunction with mulch(BMP C121). Excelsior, woven straw blankets and coir(coconut fiber)blankets may be installed without mulch. There are many other types of erosion control nets and blankets on the market that may be appropriate in certain circumstances. • In general, most nets (e.g.,jute matting) require mulch in order to prevent erosion because they have a fairly open structure. Blankets typically do not require mulch because they usually provide complete protection of the surface. • Extremely steep,unstable, wet, or rocky slopes are often appropriate candidates for use of synthetic blankets, as are riverbanks,beaches and other high-energy environments. If synthetic blankets are used, the soil should be hydromulched first. • 100-percent biodegradable blankets are available for use in sensitive areas. These organic blankets are usually held together with a paper or fiber mesh and stitching which may last up to a year. • Most netting used with blankets is photodegradable, meaning they break down under sunlight(not UV stabilized). However, this process can take months or years even under bright sun. Once vegetation is established, sunlight does not reach the mesh. It is not uncommon to find non-degraded netting still in place several years after installation. This can be a problem if maintenance requires the use of mowers or ditch cleaning equipment. In addition, birds and small animals can become trapped in the netting. Maintenance • Maintain good contact with the ground. Erosion must not occur Standards beneath the net or blanket. • Repair and staple any areas of the net or blanket that are damaged or not in close contact with the ground. • Fix and protect eroded areas if erosion occurs due to poorly controlled drainage. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-24 aIG (300 \ \ (150mm) \ \ Longitudinal Anchor Trench Terminal Slope and Channel Anchor Trench 11 g - Stake at 3'-5' (1-1.5m)intervals. � P � P P � P e P P Check slot at 25'(7.6m)intervals Isometric View P P P 6'(150mm) -W r ) (150mm) Initial Channel Anchor Trench Intermittent Check Slot NOTES: 1.Check slots to be constructed per manufacturers specifications. 2.Staking or stapling layout per manufacturers specifications. Figure 4.1.3—Channel Installation Slope surface shall be smooth before placement for proper soil contact. If there is a berm at the Stapling pattern as per top of slope,anchor manufacturer's recommendations. upslope of the berm. Min.2" Overlap �I I-I I Anchor in 6"x6"min.Trench and staple at 12" intervals. li Min.6"overlap. Ell Staple overlaps III—I 1-1 1-1 I El I l—1 I El . max.5"spacing. Bring material down to a level area,turn Do not stretch blankets/mattings tight- the end under 4"and staple at 12"intervals. allow the rolls to mold to any irregularities. For slopes less than 31-1:1 V,rolls Lime,fertilize,and seed before installation. may be placed in horizontal strips. Planting of shrubs,trees,etc.Should occur after installation. Figure 4.1.4—Slope Installation Volume II— Construction Stormwater Pollution Prevention -December 2014 4-25 BMP C123: Plastic Covering Purpose Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas. Conditions of Plastic covering may be used on disturbed areas that require cover Use measures for less than 30 days, except as stated below. • Plastic is particularly useful for protecting cut and fill slopes and stockpiles. Note: The relatively rapid breakdown of most polyethylene sheeting makes it unsuitable for long-term (greater than six months) applications. • Due to rapid runoff caused by plastic covering, do not use this method upslope of areas that might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes. • Plastic sheeting may result in increased runoff volumes and velocities, requiring additional on-site measures to counteract the increases. Creating a trough with wattles or other material can convey clean water away from these areas. • To prevent undercutting, trench and backfill rolled plastic covering products. • While plastic is inexpensive to purchase, the added cost of installation, maintenance, removal, and disposal make this an expensive material,up to $1.50-2.00 per square yard. • Whenever plastic is used to protect slopes install water collection measures at the base of the slope. These measures include plastic- covered berms, channels, and pipes used to covey clean rainwater away from bare soil and disturbed areas. Do not mix clean runoff from a plastic covered slope with dirty runoff from a project. • Other uses for plastic include: 1. Temporary ditch liner. 2. Pond liner in temporary sediment pond. 3. Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel being stored. 4. Emergency slope protection during heavy rains. 5. Temporary drainpipe ("elephant trunk")used to direct water. Design and • Plastic slope cover must be installed as follows: Installation 1. Run plastic up and down slope, not across slope. Specifications 2. Plastic may be installed perpendicular to a slope if the slope length is less than 10 feet. 3. Minimum of 8-inch overlap at seams. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-26 4. On long or wide slopes, or slopes subject to wind, tape all seams. 5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench at the top of the slope and backfill with soil to keep water from flowing underneath. 6. Place sand filled burlap or geotextile bags every 3 to 6 feet along seams and tie them together with twine to hold them in place. 7. Inspect plastic for rips, tears, and open seams regularly and repair immediately. This prevents high velocity runoff from contacting bare soil which causes extreme erosion. 8. Sandbags may be lowered into place tied to ropes. However, all sandbags must be staked in place. • Plastic sheeting shall have a minimum thickness of 0.06 millimeters. • If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable protection shall be installed at the toe of the slope in order to reduce the velocity of runoff. Maintenance • Torn sheets must be replaced and open seams repaired. Standards • Completely remove and replace the plastic if it begins to deteriorate due to ultraviolet radiation. • Completely remove plastic when no longer needed. • Dispose of old tires used to weight down plastic sheeting appropriately. Approved as Ecology has approved products as able to meet the requirements of BMP Equivalent C 123. The products did not pass through the Technology Assessment Protocol—Ecology(TAPE)process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at http://www.ecy.wa._og_v/programs/wq/stormwater/newtech/equivalent.html BMP C124: Sodding Purpose The purpose of sodding is to establish permanent turf for immediate erosion protection and to stabilize drainage ways where concentrated overland flow will occur. Conditions of Use Sodding may be used in the following areas: • Disturbed areas that require short-term or long-term cover. • Disturbed areas that require immediate vegetative cover. • All waterways that require vegetative lining. Waterways may also be seeded rather than sodded, and protected with a net or blanket. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-27 Design and Sod shall be free of weeds, of uniform thickness (approximately I-inch Installation thick), and shall have a dense root mat for mechanical strength. Specifications The following steps are recommended for sod installation: • Shape and smooth the surface to final grade in accordance with the approved grading plan. The swale needs to be overexcavated 4 to 6 inches below design elevation to allow room for placing soil amendment and sod. • Amend 4 inches (minimum) of compost into the top 8 inches of the soil if the organic content of the soil is less than ten percent or the permeability is less than 0.6 inches per hour. See hqp://www.ecy.wa.goy/programs/swfa/organics/soil.html for further information. • Fertilize according to the supplier's recommendations. • Work lime and fertilizer I to 2 inches into the soil, and smooth the surface. • Lay strips of sod beginning at the lowest area to be sodded and perpendicular to the direction of water flow. Wedge strips securely into place. Square the ends of each strip to provide for a close, tight fit. Stagger joints at least 12 inches. Staple on slopes steeper than 3H:IV. Staple the upstream edge of each sod strip. • Roll the sodded area and irrigate. • When sodding is carried out in alternating strips or other patterns, seed the areas between the sod immediately after sodding. Maintenance If the grass is unhealthy, the cause shall be determined and appropriate Standards action taken to reestablish a healthy groundcover. If it is impossible to establish a healthy groundcover due to frequent saturation, instability, or some other cause, the sod shall be removed, the area seeded with an appropriate mix, and protected with a net or blanket. BMP C125: Topsoiling / Composting Purpose Topsoiling and composting provide a suitable growth medium for final site stabilization with vegetation. While not a permanent cover practice in itself, topsoiling and composting are an integral component of providing permanent cover in those areas where there is an unsuitable soil surface for plant growth. Use this BMP in conjunction with other BMPs such as seeding, mulching, or sodding. Note that this BMP is functionally the same as BMP T5.13 (see Chapter 5 of Volume V of this manual)which is required for all disturbed areas that will be developed as lawn or landscaped areas at the completed project site. Native soils and disturbed soils that have been organically amended not only retain much more stormwater,but they also serve as effective Volume II—Construction Stormwater Pollution Prevention-December 2014 4-28 biofilters for urban pollutants and, by supporting more vigorous plant growth, reduce the water, fertilizer and pesticides needed to support installed landscapes. Topsoil does not include any subsoils but only the material from the top several inches including organic debris. Conditions of • Permanent landscaped areas shall contain healthy topsoil that reduces Use the need for fertilizers, improves overall topsoil quality,provides for better vegetal health and vitality, improves hydrologic characteristics, and reduces the need for irrigation. • Leave native soils and the duff layer undisturbed to the maximum extent practicable. Stripping of existing, properly functioning soil system and vegetation for the purpose of topsoiling during construction is not acceptable. Preserve existing soil systems in undisturbed and uncompacted conditions if functioning properly. • Areas that already have good topsoil, such as undisturbed areas, do not require soil amendments. • Restore, to the maximum extent practical, native soils disturbed during clearing and grading to a condition equal to or better than the original site condition's moisture-holding capacity. Use on-site native topsoil, incorporate amendments into on-site soil, or import blended topsoil to meet this requirement. • Topsoiling is a required procedure when establishing vegetation on shallow soils, and soils of critically low pH (high acid) levels. • Beware of where the topsoil comes from, and what vegetation was on site before disturbance, invasive plant seeds may be included and could cause problems for establishing native plants, landscaped areas, or grasses. • Topsoil from the site will contain mycorrhizal bacteria that are necessary for healthy root growth and nutrient transfer. These native mycorrhiza are acclimated to the site and will provide optimum conditions for establishing grasses. Use commercially available mycorrhiza products when using off-site topsoil. Design and Meet the following requirements for disturbed areas that will be Installation developed as lawn or landscaped areas at the completed project site: Specifications Maximize the depth of the topsoil wherever possible to provide the • maximum possible infiltration capacity and beneficial growth medium. Topsoil shall have: • A minimum depth of 8-inches. Scarify subsoils below the topsoil layer at least 4-inches with some incorporation of the upper material to avoid stratified layers, where feasible. Ripping or re- structuring the subgrade may also provide additional benefits regarding the overall infiltration and interflow dynamics of the soil system. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-29 • A minimum organic content of 10% dry weight in planting beds, and 5% organic matter content in turf areas. Incorporate organic amendments to a minimum 8-inch depth except where tree roots or other natural features limit the depth of incorporation. • A pH between 6.0 and 8.0 or matching the pH of the undisturbed soil. • If blended topsoil is imported, then fines should be limited to 25 percent passing through a 200 sieve. • Mulch planting beds with 2 inches of organic material • Accomplish the required organic content, depth, and pH by returning native topsoil to the site, importing topsoil of sufficient organic content, and/or incorporating organic amendments.When using the option of incorporating amendments to meet the organic content requirement,use compost that meets the compost specification for Bioretention(See BMP T7.30 in Chapter 7 of Volume V of this manual), with the exception that the compost may have up to 35% biosolids or manure. • Sections three through seven of the document entitled, Guidelines and Resources for Implementing Soil Quality and Depth BMP T5.13 in WDOE Stormwater Management Manual for Western Washington, provides useful guidance for implementing whichever option is chosen. It includes guidance for pre-approved default strategies and guidance for custom strategies. Check with your local jurisdiction concerning its acceptance of this guidance. It is available through the organization, Soils for Salmon. As of this printing the document may be found at: hLtp://www.soilsforsalmon.org/pdf/Soil BMP Manuql.pdf. • The final composition and construction of the soil system will result in a natural selection or favoring of certain plant species over time. For example, incorporation of topsoil may favor grasses, while layering with mildly acidic, high-carbon amendments may favor more woody vegetation. • Allow sufficient time in scheduling for topsoil spreading prior to seeding, sodding, or planting. • Take care when applying top soil to subsoils with contrasting textures. Sandy topsoil over clayey subsoil is a particularly poor combination, as water creeps along the junction between the soil layers and causes the topsoil to slough. If topsoil and subsoil are not properly bonded, water will not infiltrate the soil profile evenly and it will be difficult to establish vegetation. The best method to prevent a lack of bonding is to actually work the topsoil into the layer below for a depth of at least 6 inches. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-30 • Field exploration of the site shall be made to determine if there is surface soil of sufficient quantity and quality to justify stripping. Topsoil shall be friable and loamy(loam, sandy loam, silt loam, sandy clay loam, and clay loam). Avoid areas of natural ground water recharge. • Stripping shall be confined to the immediate construction area. A 4- inch to 6-inch stripping depth is common, but depth may vary depending on the particular soil. All surface runoff control structures shall be in place prior to stripping. • Do not place topsoil while in a frozen or muddy condition, when the subgrade is excessively wet, or when conditions exist that may otherwise be detrimental to proper grading or proposed sodding or seeding. • In any areas requiring grading remove and stockpile the duff layer and topsoil on site in a designated, controlled area, not adjacent to public resources and critical areas. Stockpiled topsoil is to be reapplied to other portions of the site where feasible. • Locate the topsoil stockpile so that it meets specifications and does not interfere with work on the site. It may be possible to locate more than one pile in proximity to areas where topsoil will be used. Stockpiling of topsoil shall occur in the following manner: • Side slopes of the stockpile shall not exceed 2H:1 V. • Between October 1 and April 30: • An interceptor dike with gravel outlet and silt fence shall surround all topsoil. • Within 2 days complete erosion control seeding, or covering stockpiles with clear plastic, or other mulching materials. • Between May 1 and September 30: • An interceptor dike with gravel outlet and silt fence shall surround all topsoil if the stockpile will remain in place for a longer period of time than active construction grading. • Within 7 days complete erosion control seeding, or covering stockpiles with clear plastic, or other mulching materials. • When native topsoil is to be stockpiled and reused the following should apply to ensure that the mycorrhizal bacterial, earthworms, and other beneficial organisms will not be destroyed: 1. Re-install topsoil within 4 to 6 weeks. 2. Do not allow the saturation of topsoil with water. 3. Do not use plastic covering. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-31 Maintenance • Inspect stockpiles regularly, especially after large storm events. Standards Stabilize any areas that have eroded. • Establish soil quality and depth toward the end of construction and once established, protect from compaction, such as from large machinery use, and from erosion. • Plant and mulch soil after installation. • Leave plant debris or its equivalent on the soil surface to replenish organic matter. • Reduce and adjust, where possible, the use of irrigation, fertilizers, herbicides and pesticides, rather than continuing to implement formerly established practices. BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection Purpose Polyacrylamide (PAM) is used on construction sites to prevent soil erosion. Applying PAM to bare soil in advance of a rain event significantly reduces erosion and controls sediment in two ways. First, PAM increases the soil's available pore volume, thus increasing infiltration through flocculation and reducing the quantity of stormwater runoff. Second, it increases flocculation of suspended particles and aids in their deposition, thus reducing stormwater runoff turbidity and improving water quality. Conditions of Use PAM shall not be directly applied to water or allowed to enter a water body. In areas that drain to a sediment pond, PAM can be applied to bare soil under the following conditions: • During rough grading operations. • In Staging areas. • Balanced cut and fill earthwork. • Haul roads prior to placement of crushed rock surfacing. • Compacted soil roadbase. • Stockpiles. • After final grade and before paving or final seeding and planting. • Pit sites. • Sites having a winter shut down. In the case of winter shut down, or where soil will remain unworked for several months, PAM should be used together with mulch. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-32 Design and PAM may be applied with water in dissolved form. The preferred Installation application method is the dissolved form. Specifications PAM is to be applied at a maximum rate of 2/3 pound PAM per 1,000 gallons water(80 mg/L)per 1 acre of bare soil. Table 4.1.9 can be used to determine the PAM and water application rate for a disturbed soil area. Higher concentrations of PAM do not provide any additional effectiveness. Table 4.1.9 PAM and Water Application Rates Disturbed Area(ac) PAM(lbs) Water(gal) 0.50 0.33 500 1.00 0.66 1,000 1.50 1.00 1,500 2.00 1.32 2,000 2.50 1.65 2,500 3.00 2.00 3,000 3.50 2.33 3,500 4.00 2.65 4,000 4.50 3.00 4,500 5.00 3.33 5,000 The Preferred Method: • Pre-measure the area where PAM is to be applied and calculate the amount of product and water necessary to provide coverage at the specified application rate (2/3 pound PAM/1000 gallons/acre). • PAM has infinite solubility in water, but dissolves very slowly. Dissolve pre-measured dry granular PAM with a known quantity of clean water in a bucket several hours or overnight. Mechanical mixing will help dissolve the PAM. Always add PAM to water-not water to PAM. • Pre-fill the water truck about 1/8 full with water. The water does not have to be potable, but it must have relatively low turbidity—in the range of 20 NTU or less. • Add PAM/Water mixture to the truck • Completely fill the water truck to specified volume. • Spray PAM/Water mixture onto dry soil until the soil surface is uniformly and completely wetted. An Alternate Method: PAM may also be applied as a powder at the rate of 5 lbs. per acre. This must be applied on a day that is dry. For areas less than 5-10 acres, a hand- held"organ grinder" fertilizer spreader set to the smallest setting will work. Tractor-mounted spreaders will work for larger areas. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-33 The following shall be used for application of powdered PAM: • Powered PAM shall be used in conjunction with other BMPs and not in place of other BMPs. • Do not use PAM on a slope that flows directly into a stream or wetland. The stormwater runoff shall pass through a sediment control BMP prior to discharging to surface waters. • Do not add PAM to water discharging from site. • When the total drainage area is greater than or equal to 5 acres, PAM treated areas shall drain to a sediment pond. • Areas less than 5 acres shall drain to sediment control BMPs, such as a minimum of 3 check dams per acre. The total number of check dams used shall be maximized to achieve the greatest amount of settlement of sediment prior to discharging from the site. Each check dam shall be spaced evenly in the drainage channel through which stormwater flows are discharged off-site. • On all sites, the use of silt fence shall be maximized to limit the discharges of sediment from the site. • All areas not being actively worked shall be covered and protected from rainfall. PAM shall not be the only cover BMP used. • PAM can be applied to wet soil, but dry soil is preferred due to less sediment loss. • PAM will work when applied to saturated soil but is not as effective as applications to dry or damp soil. • Keep the granular PAM supply out of the sun. Granular PAM loses its effectiveness in three months after exposure to sunlight and air. • Proper application and re-application plans are necessary to ensure total effectiveness of PAM usage. • PAM, combined with water, is very slippery and can be a safety hazard. Care must be taken to prevent spills of PAM powder onto paved surfaces. During an application of PAM, prevent over-spray from reaching pavement as pavement will become slippery. If PAM powder gets on skin or clothing, wipe it off with a rough towel rather than washing with water-this only makes cleanup messier and take longer. • Some PAMs are more toxic and carcinogenic than others. Only the most environmentally safe PAM products should be used. The specific PAM copolymer formulation must be anionic. Cationic PAM shall not be used in any application because of known aquatic toxicity problems. Only the highest drinking water grade PAM, certified for compliance with ANSUNSF Standard 60 for Volume II—Construction Stormwater Pollution Prevention -December 2014 4-34 drinking water treatment, will be used for soil applications. Recent media attention and high interest in PAM has resulted in some entrepreneurial exploitation of the term "polymer." All PAM are polymers, but not all polymers are PAM, and not all PAM products comply with ANSI/NSF Standard 60. PAM use shall be reviewed and approved by the local permitting authority. • PAM designated for these uses should be "water soluble" or "linear" or "non-crosslinked". Cross-linked or water absorbent PAM, polymerized in highly acidic (pH<2) conditions, are used to maintain soil moisture content. • The PAM anionic charge density may vary from 2-30 percent; a value of 18 percent is typical. Studies conducted by the United States Department of Agriculture (USDA)/ARS demonstrated that soil stabilization was optimized by using very high molecular weight (12- 15 mg/mole), highly anionic (>20%hydrolysis) PAM. • PAM tackifiers are available and being used in place of guar and alpha plantago. Typically, PAM tackifiers should be used at a rate of no more than 0.5-1 lb. per 1000 gallons of water in a hydromulch machine. Some tackifier product instructions say to use at a rate of 3 —5 lbs. per acre, which can be too much. In addition,pump problems can occur at higher rates due to increased viscosity. Maintenance • PAM may be reapplied on actively worked areas after a 48-hour Standards period. • Reapplication is not required unless PAM treated soil is disturbed or unless turbidity levels show the need for an additional application. If PAM treated soil is left undisturbed a reapplication may be necessary after two months. More PAM applications may be required for steep slopes, silty and clayey soils (USDA Classification Type "C" and "D" soils), long grades, and high precipitation areas. When PAM is applied first to bare soil and then covered with straw, a reapplication may not be necessary for several months. • Loss of sediment and PAM may be a basis for penalties per RCW 90.48.080. BMP C130: Surface Roughening Purpose Surface roughening aids in the establishment of vegetative cover, reduces runoff velocity, increases infiltration, and provides for sediment trapping through the provision of a rough soil surface. Horizontal depressions are created by operating a tiller or other suitable equipment on the contour or by leaving slopes in a roughened condition by not fine grading them. Use this BMP in conjunction with other BMPs such as seeding, mulching, or sodding. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-35 Conditions for • All slopes steeper than 3H:1 V and greater than 5 vertical feet Use require surface roughening to a depth of 2 to 4 inches prior to seeding.. • Areas that will not be stabilized immediately may be roughened to reduce runoff velocity until seeding takes place. • Slopes with a stable rock face do not require roughening. • Slopes where mowing is planned should not be excessively roughened. Design and There are different methods for achieving a roughened soil surface on a Installation slope, and the selection of an appropriate method depends upon the type of Specifications slope. Roughening methods include stair-step grading, grooving, contour furrows, and tracking. See Figure 4.1.5 for tracking and contour furrows. Factors to be considered in choosing a method are slope steepness, mowing requirements, and whether the slope is formed by cutting or filling. • Disturbed areas that will not require mowing may be stair-step graded, grooved, or left rough after filling. • Stair-step grading is particularly appropriate in soils containing large amounts of soft rock. Each "step" catches material that sloughs from above, and provides a level site where vegetation can become established. Stairs should be wide enough to work with standard earth moving equipment. Stair steps must be on contour or gullies will form on the slope. • Areas that will be mowed(these areas should have slopes less steep than 3H:IV)may have small furrows left by disking, harrowing, raking, or seed-planting machinery operated on the contour. • Graded areas with slopes steeper than 3H:IV but less than 2H:I V should be roughened before seeding. This can be accomplished in a variety of ways, including "track walking," or driving a crawler tractor up and down the slope, leaving a pattern of cleat imprints parallel to slope contours. • Tracking is done by operating equipment up and down the slope to leave horizontal depressions in the soil. Maintenance • Areas that are graded in this manner should be seeded as quickly as Standards possible. • Regular inspections should be made of the area. If rills appear, they should be re-graded and re-seeded immediately. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-36 Tracking 10 e e.e e ee ee 88ee. � �ee � � e e� eeeee ee ee e � e ee e ee ee e e e o 88 e e e e e e e e 'TRACKING'with machinery up and down the slope provides grooves that will catch seed,rainfall and reduce runoff. \ e e e Contour Furrows (15, 6"min (150mm) \\\\\ 3 Maximum Grooves Will Catch Seed, Fertilizer, and Decrease Rainfall e Runoff. /\ / X//\� Figure 4.1.5—Surface Roughening by Tracking and Contour Furrows Volume II—Construction Stormwater Pollution Prevention -December 2014 4-37 BMP C131: Gradient Terraces Purpose Gradient terraces reduce erosion damage by intercepting surface runoff and conducting it to a stable outlet at a non-erosive velocity. Conditions of Use Gradient terraces normally are limited to denuded land having a water erosion problem. They should not be constructed on deep sands or on soils that are too stony, steep, or shallow to permit practical and economical installation and maintenance. Gradient terraces may be used only where suitable outlets are or will be made available. See Figure 4.1.6 for gradient terraces. Design and The maximum vertical spacing of gradient terraces should be Installation determined by the following method: Specifications VI = (0.8)s+y Where: VI =vertical interval in feet s = land rise per 100 feet, expressed in feet y =a soil and cover variable with values from 1.0 to 4.0 Values of"y" are influenced by soil erodibility and cover practices. The lower values are applicable to erosive soils where little to no residue is left on the surface. The higher value is applicable only to erosion-resistant soils where a large amount of residue (I1/2 tons of straw/acre equivalent) is on the surface. • The minimum constructed cross-section should meet the design dimensions. • The top of the constructed ridge should not be lower at any point than the design elevation plus the specified overfill for settlement. The opening at the outlet end of the terrace should have a cross section equal to that specified for the terrace channel. • Channel grades may be either uniform or variable with a maximum grade of 0.6 feet per 100 feet length (0.6%). For short distances, terrace grades may be increased to improve alignment. The channel velocity should not exceed that which is nonerosive for the soil type. • All gradient terraces should have adequate outlets. Such an outlet may be a grassed waterway, vegetated area, or tile outlet. In all cases the outlet must convey runoff from the terrace or terrace system to a point where the outflow will not cause damage. Vegetative cover should be used in the outlet channel. • The design elevation of the water surface of the terrace should not be lower than the design elevation of the water surface in the outlet at their junction, when both are operating at design flow. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-38 • Vertical spacing determined by the above methods may be increased as much as 0.5 feet or 10 percent, whichever is greater, to provide better alignment or location, to avoid obstacles, to adjust for equipment size, or to reach a satisfactory outlet. The drainage area above the terrace should not exceed the area that would be drained by a terrace with normal spacing. • The terrace should have enough capacity to handle the peak runoff expected from a 2-year, 24-hour design storm without overtopping. • The terrace cross-section should be proportioned to fit the land slope. The ridge height should include a reasonable settlement factor. The ridge should have a minimum top width of 3 feet at the design height. The minimum cross-sectional area of the terrace channel should be 8 square feet for land slopes of 5 percent or less, 7 square feet for slopes from 5 to 8 percent, and 6 square feet for slopes steeper than 8 percent. The terrace can be constructed wide enough to be maintained using a small vehicle. Maintenance • Maintenance should be performed as needed. Terraces should be Standards inspected regularly; at least once a year, and after large storm events. Slope to adequate outlet. 10' min. i 0* ��1 �\ly��I' � I 60''�, a Figure 4.1.6—Gradient Terraces Volume II—Construction Stormwater Pollution Prevention -December 2014 4-39 BMP C140: Dust Control Purpose Dust control prevents wind transport of dust from disturbed soil surfaces onto roadways, drainage ways, and surface waters. Conditions of'Use • In areas (including roadways) subject to surface and air movement of dust where on-site and off-site impacts to roadways, drainage ways, or surface waters are likely. Design and • Vegetate or mulch areas that will not receive vehicle traffic. In areas Installation where planting, mulching, or paving is impractical, apply gravel or Specifications landscaping rock. • Limit dust generation by clearing only those areas where immediate activity will take place, leaving the remaining area(s) in the original condition. Maintain the original ground cover as long as practical. • Construct natural or artificial windbreaks or windscreens. These may be designed as enclosures for small dust sources. • Sprinkle the site with water until surface is wet. Repeat as needed. To prevent carryout of mud onto street, refer to Stabilized Construction Entrance (BMP C 105). • Irrigation water can be used for dust control. Irrigation systems should be installed as a first step on sites where dust control is a concern. • Spray exposed soil areas with a dust palliative, following the manufacturer's instructions and cautions regarding handling and application. Used oil is prohibited from use as a dust suppressant. Local governments may approve other dust palliatives such as calcium chloride or PAM. • PAM (BMP C126) added to water at a rate of 0.5 lbs. per 1,000 gallons of water per acre and applied from a water truck is more effective than water alone. This is due to increased infiltration of water into the soil and reduced evaporation. In addition, small soil particles are bonded together and are not as easily transported by wind. Adding PAM may actually reduce the quantity of water needed for dust control. Use of PAM could be a cost-effective dust control method. Techniques that can be used for unpaved roads and lots include: • Lower speed limits. High vehicle speed increases the amount of dust stirred up from unpaved roads and lots. • Upgrade the road surface strength by improving particle size, shape, and mineral types that make up the surface and base materials. • Add surface gravel to reduce the source of dust emission. Limit the amount of fine particles (those smaller than .075 mm) to 10 to 20 percent. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-40 • Use geotextile fabrics to increase the strength of new roads or roads undergoing reconstruction. • Encourage the use of alternate,paved routes, if available. • Restrict use of paved roadways by tracked vehicles and heavy trucks to prevent damage to road surface and base. • Apply chemical dust suppressants using the admix method,blending the product with the top few inches of surface material. Suppressants may also be applied as surface treatments. • Pave unpaved permanent roads and other trafficked areas. • Use vacuum street sweepers. • Remove mud and other dirt promptly so it does not dry and then turn into dust. • Limit dust-causing work on windy days. • Contact your local Air Pollution Control Authority for guidance and training on other dust control measures. Compliance with the local Air Pollution Control Authority constitutes compliance with this BMP. Maintenance Respray area as necessary to keep dust to a minimum. Standards BMP C150: Materials on Hand Purpose Keep quantities of erosion prevention and sediment control materials on the project site at all times to be used for regular maintenance and emergency situations such as unexpected heavy summer rains. Having these materials on-site reduces the time needed to implement BMPs when inspections indicate that existing BMPs are not meeting the Construction SWPPP requirements. In addition, contractors can save money by buying some materials in bulk and storing them at their office or yard. Conditions of Use Construction projects of any size or type can benefit from having materials on hand. A small commercial development project could have a roll of plastic and some gravel available for immediate protection of bare soil and temporary berm construction. A large earthwork project, such as highway construction, might have several tons of straw, several rolls of plastic, flexible pipe, sandbags, geotextile fabric and steel "T"posts. • Materials are stockpiled and readily available before any site clearing, grubbing, or earthwork begins. A large contractor or developer could keep a stockpile of materials that are available for use on several projects. • If storage space at the project site is at a premium, the contractor could maintain the materials at their office or yard. The office or yard must be less than an hour from the project site. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-41 Design and Depending on project type, size, complexity, and length, materials and Installation quantities will vary. A good minimum list of items that will cover Specifications numerous situations includes: Material Clear Plastic, 6 mil Drainpipe, 6 or 8 inch diameter Sandbags, filled Straw Bales for mulching, Quarry Spalls Washed Gravel Geotextile Fabric Catch Basin Inserts Steel "T"Posts Silt fence material Straw Wattles Maintenance • All materials with the exception of the quarry spalls, steel "T"posts, Standards and gravel should be kept covered and out of both sun and rain. • Re-stock materials used as needed. BMP C151: Concrete Handling Purpose Concrete work can generate process water and slurry that contain fine particles and high pH, both of which can violate water quality standards in the receiving water. Concrete spillage or concrete discharge to surface waters of the State is prohibited. Use this BMP to minimize and eliminate concrete, concrete process water, and concrete slurry from entering waters of the state. Conditions of Use Any time concrete is used, utilize these management practices. Concrete construction projects include, but are not limited to, the following: • Curbs • Sidewalks • Roads • Bridges • Foundations • Floors • Runways Design and Assure that washout of concrete trucks, chutes,pumps, and internals is Installation performed at an approved off-site location or in designated concrete Volume II—Construction Stormwater Pollution Prevention -December 2014 4-42 Specifications washout areas. Do not wash out concrete trucks onto the ground, or into storm drains, open ditches, streets, or streams. Refer to BMP C 154 for information on concrete washout areas. • Return unused concrete remaining in the truck and pump to the originating batch plant for recycling. Do not dump excess concrete on site, except in designated concrete washout areas. • Wash off hand tools including, but not limited to, screeds, shovels, rakes, floats, and trowels into formed areas only. • Wash equipment difficult to move, such as concrete pavers in areas that do not directly drain to natural or constructed stormwater conveyances. • Do not allow washdown from areas, such as concrete aggregate driveways, to drain directly to natural or constructed stormwater conveyances. • Contain washwater and leftover product in a lined container when no formed areas are available. Dispose of contained concrete in a manner that does not violate ground water or surface water quality standards. • Always use forms or solid barriers for concrete pours, such as pilings, within 15-feet of surface waters. • Refer to BMPs C252 and C253 for pH adjustment requirements. • Refer to the Construction Stormwater General Permit for pH monitoring requirements if the project involves one of the following activities: • Significant concrete work(greater than 1,000 cubic yards poured concrete or recycled concrete used over the life of a project). • The use of engineered soils amended with(but not limited to) Portland cement-treated base, cement kiln dust or fly ash. • Discharging stormwater to segments of water bodies on the 303(d) list(Category 5) for high pH. Maintenance Check containers for holes in the liner daily during concrete pours and Standards repair the same day. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-43 BMP C152: Sawcutting and Surfacing Pollution Prevention Purpose Sawcutting and surfacing operations generate slurry and process water that contains fine particles and high pH (concrete cutting),both of which can violate the water quality standards in the receiving water. Concrete spillage or concrete discharge to surface waters of the State is prohibited. Use this BMP to minimize and eliminate process water and slurry created through sawcutting or surfacing from entering waters of the State. Conditions of Use Utilize these management practices anytime sawcutting or surfacing operations take place. Sawcutting and surfacing operations include,but are not limited to, the following: • Sawing • Coring • Grinding • Roughening • Hydro-demolition • Bridge and road surfacing Design and • Vacuum slurry and cuttings during cutting and surfacing operations. Installation Slurry and cuttings shall not remain on permanent concrete or asphalt Specifications pavement overnight. • Slurry and cuttings shall not drain to any natural or constructed drainage conveyance including stormwater systems. This may require temporarily blocking catch basins. • Dispose of collected slurry and cuttings in a manner that does not violate ground water or surface water quality standards. • Do not allow process water generated during hydro-demolition, surface roughening or similar operations to drain to any natural or constructed drainage conveyance including stormwater systems. Dispose process water in a manner that does not violate ground water or surface water quality standards. • Handle and dispose cleaning waste material and demolition debris in a manner that does not cause contamination of water. Dispose of sweeping material from a pick-up sweeper at an appropriate disposal site. Maintenance Continually monitor operations to determine whether slurry, cuttings, or Standards process water could enter waters of the state. If inspections show that a violation of water quality standards could occur, stop operations and immediately implement preventive measures such as berms,barriers, secondary containment, and vacuum trucks. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-44 BMP C153: Material Delivery, Storage and Containment Purpose Prevent, reduce, or eliminate the discharge of pollutants to the stormwater system or watercourses from material delivery and storage. Minimize the storage of hazardous materials on-site, store materials in a designated area, and install secondary containment. Conditions of Use These procedures are suitable for use at all construction sites with delivery and storage of the following materials: • Petroleum products such as fuel, oil and grease • Soil stabilizers and binders (e.g., Polyacrylamide) • Fertilizers, pesticides and herbicides • Detergents • Asphalt and concrete compounds • Hazardous chemicals such as acids, lime, adhesives,paints, solvents, and curing compounds • Any other material that may be detrimental if released to the environment Design and The following steps should be taken to minimize risk: Installation Temporary storage area should be located away from vehicular traffic, Specifications near the construction entrance(s), and away from waterways or storm drains. • Material Safety Data Sheets (MSDS) should be supplied for all materials stored. Chemicals should be kept in their original labeled containers. • Hazardous material storage on-site should be minimized. • Hazardous materials should be handled as infrequently as possible. • During the wet weather season(Oct I —April 30), consider storing materials in a covered area. • Materials should be stored in secondary containments, such as earthen dike, horse trough, or even a children's wading pool for non-reactive materials such as detergents, oil, grease, and paints. Small amounts of material may be secondarily contained in"bus boy"trays or concrete mixing trays. • Do not store chemicals, drums, or bagged materials directly on the ground. Place these items on a pallet and, when possible, and within secondary containment. • If drums must be kept uncovered, store them at a slight angle to reduce ponding of rainwater on the lids to reduce corrosion. Domed plastic covers are inexpensive and snap to the top of drums, preventing water from collecting. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-45 Material Storage Areas and Secondary Containment Practices: • Liquids, petroleum products, and substances listed in 40 CFR Parts 110, 117, or 302 shall be stored in approved containers and drums and shall not be overfilled. Containers and drums shall be stored in temporary secondary containment facilities. • Temporary secondary containment facilities shall provide for a spill containment volume able to contain 10% of the total enclosed container volume of all containers, or 110% of the capacity of the largest container within its boundary, whichever is greater. • Secondary containment facilities shall be impervious to the materials stored therein for a minimum contact time of 72 hours. • Secondary containment facilities shall be maintained free of accumulated rainwater and spills. In the event of spills or leaks, accumulated rainwater and spills shall be collected and placed into drums. These liquids shall be handled as hazardous waste unless testing determines them to be non-hazardous. • Sufficient separation should be provided between stored containers to allow for spill cleanup and emergency response access. • During the wet weather season(Oct 1 —April 30), each secondary containment facility shall be covered during non-working days,prior to and during rain events. • Keep material storage areas clean, organized and equipped with an ample supply of appropriate spill clean-up material (spill kit). • The spill kit should include, at a minimum: • I-Water Resistant Nylon Bag • 3-Oil Absorbent Socks 3"x 4' • 2-Oil Absorbent Socks 3"x 10' • 12-Oil Absorbent Pads 17"x19" • 1-Pair Splash Resistant Goggles • 3-Pair Nitrile Gloves • 10-Disposable Bags with Ties • Instructions Volume II—Construction Stormwater Pollution Prevention -December 2014 4-46 BMP C154: Concrete Washout Area Purpose Prevent or reduce the discharge of pollutants to stormwater from concrete waste by conducting washout off-site, or performing on-site washout in a designated area to prevent pollutants from entering surface waters or ground water. Conditions of Use Concrete washout area best management practices are implemented on construction projects where: • Concrete is used as a construction material • It is not possible to dispose of all concrete wastewater and washout off-site (ready mix plant, etc.). • Concrete trucks, pumpers, or other concrete coated equipment are washed on-site. • Note: If less than 10 concrete trucks or pumpers need to be washed out on-site, the washwater may be disposed of in a formed area awaiting concrete or an upland disposal site where it will not contaminate surface or ground water. The upland disposal site shall be at least 50 feet from sensitive areas such as storm drains, open ditches, or water bodies, including wetlands. Design and Implementation Installation The following steps will help reduce stormwater pollution from concrete Specifications wastes: • Perform washout of concrete trucks at an approved off-site location or in designated concrete washout areas only. • Do not wash out concrete trucks onto the ground, or into storm drains, open ditches, streets, or streams. • Do not allow excess concrete to be dumped on-site, except in designated concrete washout areas. • Concrete washout areas may be prefabricated concrete washout containers, or self-installed structures (above-grade or below-grade). • Prefabricated containers are most resistant to damage and protect against spills and leaks. Companies may offer delivery service and provide regular maintenance and disposal of solid and liquid waste. • If self-installed concrete washout areas are used, below-grade structures are preferred over above-grade structures because they are less prone to spills and leaks. • Self-installed above-grade structures should only be used if excavation is not practical. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-47 Education • Discuss the concrete management techniques described in this BMP with the ready-mix concrete supplier before any deliveries are made. • Educate employees and subcontractors on the concrete waste management techniques described in this BMP. • Arrange for contractor's superintendent or Certified Erosion and Sediment Control Lead(CESCL)to oversee and enforce concrete waste management procedures. • A sign should be installed adjacent to each temporary concrete washout facility to inform concrete equipment operators to utilize the proper facilities. Contracts Incorporate requirements for concrete waste management into concrete supplier and subcontractor agreements. Location and Placement • Locate washout area at least 50 feet from sensitive areas such as storm drains, open ditches, or water bodies, including wetlands. • Allow convenient access for concrete trucks,preferably near the area where the concrete is being poured. • If trucks need to leave a paved area to access washout, prevent track- out with a pad of rock or quarry spalls (see BMP C 105). These areas should be far enough away from other construction traffic to reduce the likelihood of accidental damage and spills. • The number of facilities you install should depend on the expected demand for storage capacity. • On large sites with extensive concrete work, washouts should be placed in multiple locations for ease of use by concrete truck drivers. On-site Temporary Concrete Washout Facility, Transit Truck Washout Procedures: • Temporary concrete washout facilities shall be located a minimum of 50 ft from sensitive areas including storm drain inlets, open drainage facilities, and watercourses. See Figures 4.1.7 and 4.1.8. • Concrete washout facilities shall be constructed and maintained in sufficient quantity and size to contain all liquid and concrete waste generated by washout operations. • Washout of concrete trucks shall be performed in designated areas only. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-48 • Concrete washout from concrete pumper bins can be washed into concrete pumper trucks and discharged into designated washout area or properly disposed of off-site. • Once concrete wastes are washed into the designated area and allowed to harden, the concrete should be broken up, removed, and disposed of per applicable solid waste regulations. Dispose of hardened concrete on a regular basis. • Temporary Above-Grade Concrete Washout Facility • Temporary concrete washout facility(type above grade) should be constructed as shown on the details below, with a recommended minimum length and minimum width of 10 ft, but with sufficient quantity and volume to contain all liquid and concrete waste generated by washout operations. • Plastic lining material should be a minimum of 10 mil polyethylene sheeting and should be free of holes, tears, or other defects that compromise the impermeability of the material. • Temporary Below-Grade Concrete Washout Facility • Temporary concrete washout facilities (type below grade) should be constructed as shown on the details below, with a recommended minimum length and minimum width of 10 ft. The quantity and volume should be sufficient to contain all liquid and concrete waste generated by washout operations. • Lath and flagging should be commercial type. • Plastic lining material shall be a minimum of 10 mil polyethylene sheeting and should be free of holes, tears, or other defects that compromise the impermeability of the material. • Liner seams shall be installed in accordance with manufacturers' recommendations. • Soil base shall be prepared free of rocks or other debris that may cause tears or holes in the plastic lining material. Maintenance Inspection and Maintenance Standards • Inspect and verify that concrete washout BMPs are in place prior to the commencement of concrete work. • During periods of concrete work, inspect daily to verify continued performance. • Check overall condition and performance. • Check remaining capacity(% full). • If using self-installed washout facilities, verify plastic liners are intact and sidewalls are not damaged. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-49 • If using prefabricated containers, check for leaks. • Washout facilities shall be maintained to provide adequate holding capacity with a minimum freeboard of 12 inches. • Washout facilities must be cleaned, or new facilities must be constructed and ready for use once the washout is 75% full. • If the washout is nearing,capacity, vacuum and dispose of the waste material in an approved manner. • Do not discharge liquid or slurry to waterways, storm drains or directly onto ground. • Do not use sanitary sewer without local approval. • Place a secure, non-collapsing, non-water collecting cover over the concrete washout facility prior to predicted wet weather to prevent accumulation and overflow of precipitation. • Remove and dispose of hardened concrete and return the structure to a functional condition. Concrete may be reused on-site or hauled away for disposal or recycling. • When you remove materials from the self-installed concrete washout, build a new structure; or, if the previous structure is still intact, inspect for signs of weakening or damage, and make any necessary repairs. Re-line the structure with new plastic after each cleaning. Removal of Temporary Concrete Washout Facilities • When temporary concrete washout facilities are no longer required for the work, the hardened concrete, slurries and liquids shall be removed and properly disposed of. • Materials used to construct temporary concrete washout facilities shall be removed from the site of the work and disposed of or recycled. • Holes, depressions or other ground disturbance caused by the removal of the temporary concrete washout facilities shall be backfilled, repaired, and stabilized to prevent erosion. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-50 SANDBAG 10 mP PLASTIC LINRIG 10 mil PLASTIC LINING 1 m WOOD FRAME SECURELY ' FASTENED AROUND BERM ENTIRE PERIMETER WITH TWO STAKES LATH AND NOT TO SCALE FLAGGING ON yECIpN Y-B' 3 SDES NOT TO SCALE 31, MINIMUM O O TWO-STA (ED O O 21112 ROUGH 3m MINIMUM ►{ WOOD FRAME 0 B B' A A' VARIES O VARIES STAKE (TYP.) O /.. O O O SANDBAG-` 10 mil PLASTIC LINING; 10 mil PLASTIC LINING NOT TO SCALE BFRM HOT TO SCALE TYPE 'BELOW GRADE' TYPE 'ABOVE GRADE' NOTES: WITH WOOD PLANKS 1. ACTUAL LAYOUT DETERMINED IN THE FIELD. 2. THE CONCRETE WASHOUT SIGN (SEE PAGE 6) SHALL BE INSTALLED WITHIN 10 m OF THE TEMPORARY CONCRETE WASHOUT FACIUTY. Figure 4.1.7a—Concrete Washout Area Volume II—Construction Stormwater Pollution Prevention -December 2014 4-51 STRAW BALE STAPLES BINDING WIRE (2 PER BALE) 10 mil PLASTIC LINING WOOD OR METAL NATIVE MATERIAL STAKES(2 PER BALE) (OPTIONAL) SECTKW B-B' NOT TO SCALE PLYWOOD 1200 mm x610 mm 3m MINIMUM ► STAKE PAINTED WHITE (TYP-) I!CONCRETE j i =_BLACK LETTERS ��WASHOUTl� 150 mm HEIGHT __LAG SCREWS 915 mm (12.5 mm) B B. WOOD POST 915 m�m (89 mm x 89 mm x 2.4 m) VARIES I CONCRETE WASHOUT SIGN DETAIL (OR EQUIVALENT) ■ ■ ■ ■ ■ sa STRAW BALE 200 mm 1^� 3.05 mm DIA. 10 mil PLASTIC LINING (TYp.) I I� STEEL WIRE NOT TO SCAIF TYPE ABOVE GRADE' STAPLE DETAIL WITH STRAW BALES H4ffi 1. ACTUAL LAYOUT DETERMINED IN THE FIELD. 2. THE CONCRETE WASHOUT SIGN (SEE FIG. 4-1S) SHALL BE INSTALLED WITHIN 10 In OF THE TEMPORARY CONCRETE WASHOUT FACIUTTY. C. N15/FCA-14.01N0 W 8-14-02 Figure 4.1.7b—Concrete Washout Area Figure 4.1.8— Prefabricated Concrete Washout Container w/Ramp Volume II— Construction Stormwater Pollution Prevention -December 2014 4-52 BMP C160: Certified Erosion and Sediment Control Lead Purpose The project proponent designates at least one person as the responsible representative in charge of erosion and sediment control (ESC), and water quality protection. The designated person shall be the Certified Erosion and Sediment Control Lead(CESCL)who is responsible for ensuring compliance with all local, state, and federal erosion and sediment control and water quality requirements. Conditions of Use A CESCL shall be made available on projects one acre or larger that discharge stormwater to surface waters of the state. Sites less than one acre may have a person without CESCL certification conduct inspections; sampling is not required on sites that disturb less than an acre. • The CESCL shall: • Have a current certificate proving attendance in an erosion and sediment control training course that meets the minimum ESC training and certification requirements established by Ecology(see details below). Ecology will maintain a list of ESC training and certification providers at: hLtp://www.ecy.wa.goy/programs/wq/storinwater/cescl.html OR • Be a Certified Professional in Erosion and Sediment Control (CPESC); for additional information go to: www.cpesc.net Specifications • Certification shall remain valid for three years. • The CESCL shall have authority to act on behalf of the contractor or developer and shall be available, or on-call, 24 hours per day throughout the period of construction. • The Construction SWPPP shall include the name, telephone number, fax number, and address of the designated CESCL. • A CESCL may provide inspection and compliance services for multiple construction projects in the same geographic region. Duties and responsibilities of the CESCL shall include, but are not limited to the following: • Maintaining permit file on site at all times which includes the Construction SWPPP and any associated permits and plans. • Directing BMP installation, inspection, maintenance, modification, and removal. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-53 • Updating all project drawings and the Construction SWPPP with changes made. • Completing any sampling requirements including reporting results using WebDMR. • Keeping daily logs, and inspection reports. Inspection reports should include: • Inspection date/time. • Weather information; general conditions during inspection and approximate amount of precipitation since the last inspection. • A summary or list of all BMPs implemented, including observations of all erosion/sediment control structures or practices. The following shall be noted: 1. Locations of BMPs inspected. 2. Locations of BMPs that need maintenance. 3. Locations of BMPs that failed to operate as designed or intended. 4. Locations of where additional or different BMPs are required. • Visual monitoring results, including a description of discharged stormwater. The presence of suspended sediment, turbid water, discoloration, and oil sheen shall be noted, as applicable. • Any water quality monitoring performed during inspection. • General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. • Facilitate, participate in, and take corrective actions resulting from inspections performed by outside agencies or the owner. BMP C162: Scheduling Purpose Sequencing a construction project reduces the amount and duration of soil exposed to erosion by wind, rain, runoff, and vehicle tracking. Conditions of Use The construction sequence schedule is an orderly listing of all major land- disturbing activities together with the necessary erosion and sedimentation control measures planned for the project. This type of schedule guides the contractor on work to be done before other work is started so that serious erosion and sedimentation problems can be avoided. Following a specified work schedule that coordinates the timing of land- disturbing activities and the installation of control measures is perhaps the most cost-effective way of controlling erosion during construction. The removal of surface ground cover leaves a site vulnerable to accelerated Volume II—Construction Stormwater Pollution Prevention -December 2014 4-54 erosion. Construction procedures that limit land clearing provide timely installation of erosion and sedimentation controls, and restore protective cover quickly can significantly reduce the erosion potential of a site. Design Minimize construction during rainy periods. Considerations Schedule projects to disturb only small portions of the site at any one • time. Complete grading as soon as possible. Immediately stabilize the disturbed portion before grading the next portion. Practice staged seeding in order to revegetate cut and fill slopes as the work progresses. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-SS Table 4.2.1 Runoff Conveyance and Treatment BMPs by SWPPP Element _ v _ O v U U N O U ++ ro O +p+ +p+ � *' Q p0 in iJ O O co O E' U C 00 a a N -p U O M C M v U % n ao � M -4 .� 3 v BMP or Element Name u OJ u �, U a, U p G +� in on C � C 41 C C C C N in C � C � C +' p' (U G1 E (U (U p a) C (U ++ N O '� y N O N W L.L ai w Ln w Ln W W U O W a_ W U > W d 0 BMP C200:Interceptor Dike and Swale ✓ ✓ BMP C201:Grass-Lined Channels ✓ ✓ BMP C202:Channel Lining ✓ BMP C203:Water Bars ✓ ✓ ✓ BMP C204:Pipe Slope Drains ✓ BMP C205:Subsurface Drains ✓ BMP C206:Level Spreader ✓ ✓ BMP C207:Check Dams ✓ ✓ ✓ ✓ BMP C208:Triangular Silt Dike(TSD) ✓ ✓ (Geotextile Encased Check Dam) BMP C209:Outlet Protection ✓ ✓ BMP C220:Storm Drain Inlet ✓ Protection BMP C231:Brush Barrier ✓ ✓ BMP C232:Gravel Filter Berm ✓ BMP C233:Silt Fence ✓ ✓ BMP C234:Vegetated Strip ✓ ✓ BMP C235:Wattles ✓ ✓ BMP C236:Vegetated Filtration ✓ BMP C240:Sediment Trap ✓ ✓ BMP C241:Temporary Sediment Pond ✓ ✓ Volume II— Construction Stormwater Pollution Prevention -December 2014 4-56 BMP C250:Construction Stormwater Chemical Treatment BMP C251:Construction Stormwater ✓ Filtration BMP C252:High pH Neutralization Using CO2 BMP C253:pH Control for High pH ✓ Water BMP C200: Interceptor Dike and Swale Purpose Provide a ridge of compacted soil, or a ridge with an upslope swale, at the top or base of a disturbed slope or along the perimeter of a disturbed construction area to convey stormwater. Use the dike and/or swale to intercept the runoff from unprotected areas and direct it to areas where erosion can be controlled. This can prevent storm runoff from entering the work area or sediment-laden runoff from leaving the construction site. Conditions of Use Where the runoff from an exposed site or disturbed slope must be conveyed to an erosion control facility which can safely convey the stormwater. • Locate upslope of a construction site to prevent runoff from entering disturbed area. • When placed horizontally across a disturbed slope, it reduces the amount and velocity of runoff flowing down the slope. • Locate downslope to collect runoff from a disturbed area and direct water to a sediment basin. Design and • Dike and/or swale and channel must be stabilized with temporary or Installation permanent vegetation or other channel protection during construction. Specifications • Channel requires a positive grade for drainage; steeper grades require channel protection and check dams. • Review construction for areas where overtopping may occur. • Can be used at top of new fill before vegetation is established. • May be used as a permanent diversion channel to carry the runoff. • Sub-basin tributary area should be one acre or less. • Design capacity for the peak volumetric flow rate calculated using a 10-minute time step from a 10-year, 24-hour storm, assuming a Type IA rainfall distribution, for temporary facilities. Alternatively,use 1.6 times the 10-year, 1-hour flow indicated by an approved continuous runoff model. For facilities that will also serve on a permanent basis, consult the local government's drainage requirements. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-57 Interceptor dikes shall meet the following criteria: Top Width 2 feet minimum. Height 1.5 feet minimum on berm. Side Slope 2H:1 V or flatter. Grade Depends on topography, however, dike system minimum is 0.5%, and maximum is 1%. Compaction Minimum of 90 percent ASTM D698 standard proctor. Horizontal Spacing of Interceptor Dikes: Average Slope Slope Percent Flowpath Length 20H:1V or less 3-5% 300 feet (10 to 20)H:1V 5-10% 200 feet (4 to 10)H:1V 10-25% 100 feet (2 to 4)H:1 V 25-50% 50 feet Stabilization depends on velocity and reach Slopes<5% Seed and mulch applied within 5 days of dike construction(see BMP C 121, Mulching). Slopes 5 - 40% Dependent on runoff velocities and dike materials. Stabilization should be done immediately using either sod or riprap or other measures to avoid erosion. • The upslope side of the dike shall provide positive drainage to the dike outlet. No erosion shall occur at the outlet. Provide energy dissipation measures as necessary. Sediment-laden runoff must be released through a sediment trapping facility. • Minimize construction traffic over temporary dikes. Use temporary cross culverts for channel crossing. Interceptor swales shall meet the following criteria: Bottom Width 2 feet minimum; the cross-section bottom shall be level. Depth 1-foot minimum. Side Slope 2H:1V or flatter. Grade Maximum 5 percent, with positive drainage to a suitable outlet(such as a sediment pond). Stabilization Seed as per BMP C 120, Temporary and Permanent Seeding, or BMP C202, Channel Lining, 12 inches thick riprap pressed into the bank and extending at least 8 inches vertical from the bottom. • Inspect diversion dikes and interceptor swales once a week and after every rainfall. Immediately remove sediment from the flow area. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-58 • Damage caused by construction traffic or other activity must be repaired before the end of each working day. Check outlets and make timely repairs as needed to avoid gully formation. When the area below the temporary diversion dike is permanently stabilized, remove the dike and fill and stabilize the channel to blend with the natural surface. BMP C201: Grass-Lined Channels Purpose To provide a channel with a vegetative lining for conveyance of runoff. See Figure 4.2.1 for typical grass-lined channels. Conditions of Use This practice applies to construction sites where concentrated runoff needs to be contained to prevent erosion or flooding. • When a vegetative lining can provide sufficient stability for the channel cross section and at lower velocities of water(normally dependent on grade). This means that the channel slopes are generally less than 5 percent and space is available for a relatively large cross section. • Typical uses include roadside ditches, channels at property boundaries, outlets for diversions, and other channels and drainage ditches in low areas. • Channels that will be vegetated should be installed before major earthwork and hydroseeded with a bonded fiber matrix (BFM). The vegetation should be well established(i.e., 75 percent cover)before water is allowed to flow in the ditch. With channels that will have high flows, erosion control blankets should be installed over the hydroseed. If vegetation cannot be established from seed before water is allowed in the ditch, sod should be installed in the bottom of the ditch in lieu of hydromulch and blankets. Design and Locate the channel where it can conform to the topography and other Installation features such as roads. Specifications . Locate them to use natural drainage systems to the greatest extent possible. • Avoid sharp changes in alignment or bends and changes in grade. • Do not reshape the landscape to fit the drainage channel. • The maximum design velocity shall be based on soil conditions, type of vegetation, and method of revegetation, but at no times shall velocity exceed 5 feet/second. The channel shall not be overtopped by the peak volumetric flow rate calculated using a 10-minute time step from a 10-year, 24-hour storm, assuming a Type I rainfall distribution. Alternatively, use 1.6 times the 10-year, 1-hour flow indicated by an approved continuous runoff model to determine a flow rate which the channel must contain. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-59 • Where the grass-lined channel will also function as a permanent stormwater conveyance facility, consult the drainage conveyance requirements of the local government with jurisdiction. • An established grass or vegetated lining is required before the channel can be used to convey stormwater, unless stabilized with nets or blankets. • If design velocity of a channel to be vegetated by seeding exceeds 2 ft/sec, a temporary channel liner is required. Geotextile or special mulch protection such as fiberglass roving or straw and netting provides stability until the vegetation is fully established. See Figure 4.2.2. • Check dams shall be removed when the grass has matured sufficiently to protect the ditch or swale unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. • If vegetation is established by sodding, the permissible velocity for established vegetation may be used and no temporary liner is needed. • Do not subject grass-lined channel to sedimentation from disturbed areas. Use sediment-trapping BMPs upstream of the channel. • V-shaped grass channels generally apply where the quantity of water is small, such as in short reaches along roadsides. The V-shaped cross section is least desirable because it is difficult to stabilize the bottom where velocities may be high. • Trapezoidal grass channels are used where runoff volumes are large and slope is low so that velocities are nonerosive to vegetated linings. (Note: it is difficult to construct small parabolic shaped channels.) • Subsurface drainage, or riprap channel bottoms, may be necessary on sites that are subject to prolonged wet conditions due to long duration flows or a high water table. • Provide outlet protection at culvert ends and at channel intersections. • Grass channels, at a minimum, should carry peak runoff for temporary construction drainage facilities from the 10-year, 24-hour storm without eroding. Where flood hazard exists, increase the capacity according to the potential damage. • Grassed channel side slopes generally are constructed 3H:1 V or flatter to aid in the establishment of vegetation and for maintenance. • Construct channels a minimum of 0.2 foot larger around the periphery to allow for soil bulking during seedbed preparations and sod buildup. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-60 Maintenance During the establishment period, check grass-lined channels after every Standards rainfall. • After grass is established, periodically check the channel; check it after every heavy rainfall event. Immediately make repairs. • It is particularly important to check the channel outlet and all road crossings for bank stability and evidence of piping or scour holes. • Remove all significant sediment accumulations to maintain the designed carrying capacity. Keep the grass in a healthy, vigorous condition at all times, since it is the primary erosion protection for the channel. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-61 Typical V-Shaped Channel Cross-section Filter (150-225mmi Fabric i��/�\ Key in Fabric Grass-Lined With Rock Center Typical Parabolic Channel Cross-Section �� Ili a Ali 6"-9" 050-225mm) /\\ j\ Filter /. Key In Fabric Fabric I with Channel Liner With Rock Center for Base Flow Typical Trapezoidal Channel Cross-Section Design Depth \ \\I Dvercut channel bulking during /�\\ \\;�\\j�\j: \�\\\��\\// to seedbed preparation and growth of vegetation. Filter \ With Rock Center For Base Flow Fabric Figure 4.2.1 —Typical Grass-Lined Channels Volume H Construction Stormwater Pollution Prevention -December 2014 4-62 `1 Overlap 6'(150mm)minimum Excavate Channel to Design �. Grade and Cross Section \ � �9 (n DeP OVERCUTCHANNEL Longitudinal 2'(50mm) TOALLOW anchor trench BULKING DURING SEEDBED PREPARATION rr ► TYPICAL INSTALLATION \ \ \ WITHEROSIONCONTROL BLANKETS OR TURF REINFORCEMENTMATS \/\\/\\/ \/\\/\\ Intermittent Check Slot Longitudinal Anchor Trench Shingle-lap spliced ends or begin new roll in an intermittent check slot Prepare soil and apply seed before installing blankets,mats or other N temporary channel liner system NOTES: 1 Design velocities exceeding 2 ft/sec (0.5m/sec)require temporary blankets, mats or similar liners to protect seed and soil until vegetation becomes established. 2 Grass-lined channels with design velocities exceeding 6 ft/sec (2m/sec) should include turf reinforcement mats. Figure 4.2.2—Temporary Channel Liners Volume II— Construction Stormwater Pollution Prevention -December 2014 4-63 BMP C202: Channel Lining Purpose To protect channels by providing a channel liner using either blankets or riprap. Conditions of When natural soils or vegetated stabilized soils in a channel are not adequate Use to prevent channel erosion. • When a permanent ditch or pipe system is to be installed and a temporary measure is needed. • In almost all cases, synthetic and organic coconut blankets are more effective than riprap for protecting channels from erosion. Blankets can be used with and without vegetation. Blanketed channels can be designed to handle any expected flow and longevity requirement. Some synthetic blankets have a predicted life span of 50 years or more, even in sunlight. • Other reasons why blankets are better than rock include the availability of blankets over rock. In many areas of the state, rock is not easily obtainable or is very expensive to haul to a site. Blankets can be delivered anywhere. Rock requires the use of dump trucks to haul and heavy equipment to place. Blankets usually only require laborers with hand tools, and sometimes a backhoe. • The Federal Highway Administration recommends not using flexible liners whenever the slope exceeds 10 percent or the shear stress exceeds 8 lbs/fe. Design and See BMP C 122 for information on blankets. Installation Since riprap is used where erosion potential is high, construction must be Specifications sequenced so that the riprap is put in place with the minimum possible delay. • Disturbance of areas where riprap is to be placed should be undertaken only when final preparation and placement of the riprap can follow immediately behind the initial disturbance. Where riprap is used for outlet protection, the riprap should be placed before or in conjunction with the construction of the pipe or channel so that it is in place when the pipe or channel begins to operate. • The designer, after determining the riprap size that will be stable under the flow conditions, shall consider that size to be a minimum size and then, based on riprap gradations actually available in the area, select the size or sizes that equal or exceed the minimum size. The possibility of drainage structure damage by children shall be considered in selecting a riprap size, especially if there is nearby water or a gully in which to toss the stones. • Stone for riprap shall consist of field stone or quarry stone of approximately rectangular shape. The stone shall be hard and angular Volume II—Construction Stormwater Pollution Prevention -December 2014 4-64 and of such quality that it will not disintegrate on exposure to water or weathering and it shall be suitable in all respects for the purpose intended. • A lining of engineering filter fabric (geotextile) shall be placed between the riprap and the underlying soil surface to prevent soil movement into or through the riprap. The geotextile should be keyed in at the top of the bank. • Filter fabric shall not be used on slopes greater than 1-1/2H:1V as slippage may occur. It should be used in conjunction with a layer of coarse aggregate (granular filter blanket)when the riprap to be placed is 12 inches and larger. BMP C203: Water Bars Purpose A small ditch or ridge of material is constructed diagonally across a road or right-of-way to divert stormwater runoff from the road surface, wheel tracks, or a shallow road ditch. See Figure 4.2.3. Conditions of use Clearing right-of-way and construction of access for power lines, pipelines, and other similar installations often require long narrow right-of-ways over sloping terrain. Disturbance and compaction promotes gully formation in these cleared strips by increasing the volume and velocity of runoff. Gully formation may be especially severe in tire tracks and ruts. To prevent gullying, runoff can often be diverted across the width of the right-of-way to undisturbed areas by using small predesigned diversions. • Give special consideration to each individual outlet area, as well as to the cumulative effect of added diversions. Use gravel to stabilize the diversion where significant vehicular traffic is anticipated. Design and Height: 8-inch minimum measured from the channel bottom to the ridge top. Installation Side slope of channel: 2H:1 V maximum; 3H:1 V or flatter when vehicles Specifications will cross. • Base width of ridge: 6-inch minimum. • Locate them to use natural drainage systems and to discharge into well vegetated stable areas. • Guideline for Spacing: Slope % Spacing (ft) < 5 125 5 - 10 100 10 -20 75 20 - 35 50 > 35 Use rock lined ditch Volume II—Construction Stormwater Pollution Prevention -December 2014 4-65 • Grade of water bar and angle: Select angle that results in ditch slope less than 2 percent. • Install as soon as the clearing and grading is complete. Reconstruct when construction is complete on a section when utilities are being installed. • Compact the ridge when installed. • Stabilize, seed, and mulch the portions that are not subject to traffic. Gravel the areas crossed by vehicles. Maintenance Periodically inspect right-of-way diversions for wear and after every heavy Standards rainfall for erosion damage. • Immediately remove sediment from the flow area and repair the dike. • Check outlet areas and make timely repairs as needed. • When permanent road drainage is established and the area above the temporary right-of-way diversion is permanently stabilized, remove the dikes and fill the channel to blend with the natural ground, and appropriately stabilize the disturbed area. ated l(l � io m dip to const ct . r; DE EP VIA TE R BA R �,B;;I � R A=24 to 30 inches ?' �/ �� O B-6 to 10 feet '• �� SHALLOW WATER BAR A=8 to 1 2 inches B=6to12feet Figure 4.2.3—Water Bar Volume II—Construction Stormwater Pollution Prevention -December 2014 4-66 BMP C204: Pipe Slope Drains Purpose To use a pipe to convey stormwater anytime water needs to be diverted away from or over bare soil to prevent gullies, channel erosion, and saturation of slide-prone soils. Conditions of Use Pipe slope drains should be used when a temporary or permanent stormwater conveyance is needed to move the water down a steep slope to avoid erosion(Figure 4.2.4). On highway projects, pipe slope drains should be used at bridge ends to collect runoff and pipe it to the base of the fill slopes along bridge approaches. These can be designed into a project and included as bid items. Another use on road projects is to collect runoff from pavement and pipe it away from side slopes. These are useful because there is generally a time lag between having the first lift of asphalt installed and the curbs, gutters, and permanent drainage installed. Used in conjunction with sand bags, or other temporary diversion devices, these will prevent massive amounts of sediment from leaving a project. Water can be collected, channeled with sand bags, Triangular Silt Dikes, berms, or other material, and piped to temporary sediment ponds. Pipe slope drains can be: • Connected to new catch basins and used temporarily until all permanent piping is installed; • Used to drain water collected from aquifers exposed on cut slopes and take it to the base of the slope; • Used to collect clean runoff from plastic sheeting and direct it away from exposed soil; • Installed in conjunction with silt fence to drain collected water to a controlled area; • Used to divert small seasonal streams away from construction. They have been used successfully on culvert replacement and extension jobs. Large flex pipe can be used on larger streams during culvert removal, repair, or replacement; and, • Connected to existing down spouts and roof drains and used to divert water away from work areas during building renovation, demolition, and construction projects. There are now several commercially available collectors that are attached to the pipe inlet and help prevent erosion at the inlet. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-67 Design and Size the pipe to convey the flow. The capacity for temporary drains shall be Installation sufficient to handle the peak volumetric flow rate calculated using a 10- Specifications minute time step from a 10-year, 24-hour storm event, assuming a Type IA rainfall distribution. Alternatively, use 1.6 times the 10-year, 1-hour flow indicated by an approved continuous runoff model. Consult local drainage requirements for sizing permanent pipe slope drains. • Use care in clearing vegetated slopes for installation. • Re-establish cover immediately on areas disturbed by installation. • Use temporary drains on new cut or fill slopes. • Use diversion dikes or swales to collect water at the top of the slope. • Ensure that the entrance area is stable and large enough to direct flow into the pipe. • Piping of water through the berm at the entrance area is a common failure mode. • The entrance shall consist of a standard flared end section for culverts 12 inches and larger with a minimum 6-inch metal toe plate to prevent runoff from undercutting the pipe inlet. The slope of the entrance shall be at least 3 percent. Sand bags may also be used at pipe entrances as a temporary measure. • The soil around and under the pipe and entrance section shall be thoroughly compacted to prevent undercutting. • The flared inlet section shall be securely connected to the slope drain and have watertight connecting bands. • Slope drain sections shall be securely fastened together, fused or have gasketed watertight fittings, and shall be securely anchored into the soil. • Thrust blocks should be installed anytime 90 degree bends are utilized. Depending on size of pipe and flow, these can be constructed with sand bags, straw bales staked in place, "t"posts and wire, or ecology blocks. • Pipe needs to be secured along its full length to prevent movement. This can be done with steel "t"posts and wire. A post is installed on each side of the pipe and the pipe is wired to them. This should be done every 10-20 feet of pipe length or so, depending on the size of the pipe and quantity of water to divert. • Interceptor dikes shall be used to direct runoff into a slope drain. The height of the dike shall be at least 1 foot higher at all points than the top of the inlet pipe. • The area below the outlet must be stabilized with a riprap apron (see BMP C209 Outlet Protection, for the appropriate outlet material). Volume II—Construction Stormwater Pollution Prevention -December 2014 4-68 • If the pipe slope drain is conveying sediment-laden water, direct all flows into the sediment trapping facility. • Materials specifications for any permanent piped system shall be set by the local government. Maintenance Check inlet and outlet points regularly, especially after storms. Standards The inlet should be free of undercutting, and no water should be going around the point of entry. If there are problems, the headwall should be reinforced with compacted earth or sand bags. • The outlet point should be free of erosion and installed with appropriate outlet protection. • For permanent installations, inspect pipe periodically for vandalism and physical distress such as slides and wind-throw. • Normally the pipe slope is so steep that clogging is not a problem with smooth wall pipe, however, debris may become lodged in the pipe. Dike material compacted 90%modified proctor CPEP or equivalent pipe Interceptor Dike 12' WIN. \ — Provide riprap pad �L —_� or equivalent energy dissipation Discharge to a stabilized Standard flared watercourse,sediment retention end section facility,or stabilized outlet Inlet and all sections must be securely fastened together with gasketed watertight fittings Figure 4.2.4— Pipe Slope Drain Volume II—Construction Stormwater Pollution Prevention -December 2014 4-69 BMP C205: Subsurface Drains Purpose To intercept, collect, and convey ground water to a satisfactory outlet, using a perforated pipe or conduit below the ground surface. Subsurface drains are also known as "french drains."The perforated pipe provides a dewatering mechanism to drain excessively wet soils, provide a stable base for construction, improve stability of structures with shallow foundations, or to reduce hydrostatic pressure to improve slope stability. Conditions of Use Use when excessive water must be removed from the soil. The soil permeability, depth to water table and impervious layers are all factors which may govern the use of subsurface drains. Design and Relief drains are used either to lower the water table in large, relatively Installation flat areas, improve the growth of vegetation, or to remove surface water. Specifications Relief drains are installed along a slope and drain in the direction of the slope. They can be installed in a grid pattern, a herringbone pattern, or a random pattern. • Interceptor drains are used to remove excess ground water from a slope, stabilize steep slopes, and lower the water table immediately below a slope to prevent the soil from becoming saturated. Interceptor drains are installed perpendicular to a slope and drain to the side of the slope. They usually consist of a single pipe or series of single pipes instead of a patterned layout. • Depth and spacing of interceptor drains --The depth of an interceptor drain is determined primarily by the depth to which the water table is to be lowered or the depth to a confining layer. For practical reasons, the maximum depth is usually limited to 6 feet, with a minimum cover of 2 feet to protect the conduit. • The soil should have depth and sufficient permeability to permit installation of an effective drainage system at a depth of 2 to 6 feet. • An adequate outlet for the drainage system must be available either by gravity or by pumping. • The quantity and quality of discharge needs to be accounted for in the receiving stream(additional detention may be required). • This standard does not apply to subsurface drains for building foundations or deep excavations. • The capacity of an interceptor drain is determined by calculating the maximum rate of ground water flow to be intercepted. Therefore, it is Volume II—Construction Stormwater Pollution Prevention -December 2014 4-70 good practice to make complete subsurface investigations, including hydraulic conductivity of the soil,before designing a subsurface drainage system. • Size of drain--Size subsurface drains to carry the required capacity without pressure flow. Minimum diameter for a subsurface drain is 4 inches. • The minimum velocity required to prevent silting is 1.4 ft./sec. The line shall be graded to achieve this velocity at a minimum. The maximum allowable velocity using a sand-gravel filter or envelope is 9 ft/sec. • Filter material and fabric shall be used around all drains for proper bedding and filtration of fine materials. Envelopes and filters should surround the drain to a minimum of 3-inch thickness. • The outlet of the subsurface drain shall empty into a sediment pond through a catch basin. If free of sediment, it can then empty into a receiving channel, swale, or stable vegetated area adequately protected from erosion and undermining. • The trench shall be constructed on a continuous grade with no reverse grades or low spots. • Soft or yielding soils under the drain shall be stabilized with gravel or other suitable material. • Backfilling shall be done immediately after placement of the pipe. No sections of pipe shall remain uncovered overnight or during a rainstorm. Backfill material shall be placed in the trench in such a manner that the drain pipe is not displaced or damaged. • Do not install permanent drains near trees to avoid the tree roots that tend to clog the line. Use solid pipe with watertight connections where it is necessary to pass a subsurface drainage system through a stand of trees. • Outlet--Ensure that the outlet of a drain empties into a channel or other watercourse above the normal water level. • Secure an animal guard to the outlet end of the pipe to keep out rodents. • Use outlet pipe of corrugated metal, cast iron, or heavy-duty plastic without perforations and at least 10 feet long. Do not use an envelope or filter material around the outlet pipe, and bury at least two-thirds of the pipe length. • When outlet velocities exceed those allowable for the receiving stream, outlet protection must be provided. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-71 Maintenance Subsurface drains shall be checked periodically to ensure that they are Standards free-flowing and not clogged with sediment or roots. • The outlet shall be kept clean and free of debris. • Surface inlets shall be kept open and free of sediment and other debris. • Trees located too close to a subsurface drain often clog the system with their roots. If a drain becomes clogged, relocate the drain or remove the trees as a last resort. Drain placement should be planned to minimize this problem. • Where drains are crossed by heavy vehicles, the line shall be checked to ensure that it is not crushed. BMP C206: Level Spreader Purpose To provide a temporary outlet for dikes and diversions consisting of an excavated depression constructed at zero grade across a slope. To convert concentrated runoff to sheet flow and release it onto areas stabilized by existing vegetation or an engineered filter strip. Conditions of Use Used when a concentrated flow of water needs to be dispersed over a large area with existing stable vegetation. • Items to consider are: 1. What is the risk of erosion or damage if the flow may become concentrated? 2. Is an easement required if discharged to adjoining property? 3. Most of the flow should be as ground water and not as surface flow. 4. Is there an unstable area downstream that cannot accept additional ground water? • Use only where the slopes are gentle, the water volume is relatively low, and the soil will adsorb most of the low flow events. Design and Use above undisturbed areas that are stabilized by existing vegetation. Installation If the level spreader has any low points, flow will concentrate, create Specifications channels and may cause erosion. • Discharge area below the outlet must be uniform with a slope flatter than 5H:IV. • Outlet to be constructed level in a stable, undisturbed soil profile (not on fill). • The runoff shall not re-concentrate after release unless intercepted by another downstream measure. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-72 • The grade of the channel for the last 20 feet of the dike or interceptor entering the level spreader shall be less than or equal to 1 percent. The grade of the level spreader shall be 0 percent to ensure uniform spreading of storm runoff. • A 6-inch high gravel berm placed across the level lip shall consist of washed crushed rock, 2-to 4-inch or 3/4-inch to 11/2-inch size. • The spreader length shall be determined by estimating the peak flow expected from the 10-year, 24-hour design storm. The length of the spreader shall be a minimum of 15 feet for 0.1 cfs and shall increase by 10 feet for each 0.1 cfs thereafter to a maximum of 0.5 cfs per spreader. Use multiple spreaders for higher flows. • The width of the spreader should be at least 6 feet. • The depth of the spreader as measured from the lip should be at least 6 inches and it should be uniform across the entire length. • Level spreaders shall be setback from the property line unless there is an easement for flow. • Level spreaders, when installed every so often in grassy swales, keep the flows from concentrating. Materials that can be used include sand bags, lumber, logs, concrete, and pipe. To function properly, the material needs to be installed level and on contour. F 4.2.5Fi. rug e425 and 4.2.6 provide a cross-section and a detail of a level spreader. A capped perforated pipe could also be used as a spreader. Maintenance The spreader should be inspected after every runoff event to ensure that it Standards is functioning correctly. • The contractor should avoid the placement of any material on the structure and should prevent construction traffic from crossing over the structure. • If the spreader is damaged by construction traffic, it shall be immediately repaired. Pressure-Treated 2"x10" Densely vegetated for a Min. of 100' and slope tea+—�— less than 5:1 �N 1'Min. III=I -''� 3' Min. Figure 4.2.5—Cross Section of Level Spreader Volume II—Construction Stormwater Pollution Prevention -December 2014 4-73 Treated 2"x10" may be abutted end to Spreader must be level end for max. spreader length of 50' 6" min. 1" min. 6" min. II=III=III=1 I—III—III—III—III+F1=III—III=III=III=11 III=III=III 18" min. rebar supports 8' max. spacing Figure 4.2.6— Detail of Level Spreader BMP C207: Check Dams Purpose Construction of small dams across a swale or ditch reduces the velocity of concentrated flow and dissipates energy at the check dam. Conditions of Use Where temporary channels or permanent channels are not yet vegetated, channel lining is infeasible, and/or velocity checks are required. • Check dams may not be placed in streams unless approved by the State Department of Fish and Wildlife. Check dams may not be placed in wetlands without approval from a permitting agency. • Do not place check dams below the expected backwater from any salmonid bearing water between October 1 and May 31 to ensure that there is no loss of high flow refuge habitat for overwintering juvenile salmonids and emergent salmonid fry. • Construct rock check dams from appropriately sized rock. The rock used must be large enough to stay in place given the expected design flow through the channel. The rock must be placed by hand or by mechanical means (no dumping of rock to form dam)to achieve complete coverage of the ditch or swale and to ensure that the center of the dam is lower than the edges. • Check dams may also be constructed of either rock or pea-gravel filled bags. Numerous new products are also available for this purpose. They tend to be re-usable, quick and easy to install, effective, and cost efficient. • Place check dams perpendicular to the flow of water. • The dam should form a triangle when viewed from the side. This prevents undercutting as water flows over the face of the dam rather than falling directly onto the ditch bottom. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-74 • Before installing check dams impound and bypass upstream water flow away from the work area. Options for bypassing include pumps, siphons, or temporary channels. • Check dams in association with sumps work more effectively at slowing flow and retaining sediment than just a check dam alone. A deep sump should be provided immediately upstream of the check dam. • In some cases, if carefully located and designed, check dams can remain as permanent installations with very minor regrading. They may be left as either spillways, in which case accumulated sediment would be graded and seeded, or as check dams to prevent further sediment from leaving the site. • The maximum spacing between the dams shall be such that the toe of the upstream dam is at the same elevation as the top of the downstream dam. • Keep the maximum height at 2 feet at the center of the dam. • Keep the center of the check dam at least 12 inches lower than the outer edges at natural ground elevation. • Keep the side slopes of the check dam at 211:1 V or flatter. • Key the stone into the ditch banks and extend it beyond the abutments a minimum of 18 inches to avoid washouts from overflow around the dam. • Use filter fabric foundation under a rock or sand bag check dam. If a blanket ditch liner is used, filter fabric is not necessary. A piece of organic or synthetic blanket cut to fit will also work for this purpose. • In the case of grass-lined ditches and swales, all check dams and accumulated sediment shall be removed when the grass has matured sufficiently to protect the ditch or swale -unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. • Ensure that channel appurtenances, such as culvert entrances below check dams, are not subject to damage or blockage from displaced stones. Figure 4.2.7 depicts a typical rock check dam. Maintenance Check dams shall be monitored for performance and sediment Standards accumulation during and after each runoff producing rainfall. Sediment shall be removed when it reaches one half the sump depth. • Anticipate submergence and deposition above the check dam and erosion from high flows around the edges of the dam. • If significant erosion occurs between dams, install a protective riprap liner in that portion of the channel. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-75 Approved as Ecology has approved products as able to meet the requirements of BMP Equivalent C207. The products did not pass through the Technology Assessment Protocol—Ecology(TAPE)process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at hM2://www.ecy.wa.gov/pro,grams/wq/stormwater/newtech/equivalent.html Volume II—Construction Stormwater Pollution Prevention -December 2014 4-76 View Looking Upstream A 18"(0.5m) 12" (150mm) s° °° ° ° oo * o�o ��go °�i 24"(0.6m) NOTE: °off° °oo o��o °° i o° Key stone into channel banks and extend it beyond the abutments a minimum of 18"(0.5m)to prevent A flow around dam. Section A - A FLOW 24" (0.6m) �0000 °e °�ao00000 on �e Oo o 8' (2.4m) Spacing Between Check Dams 'L'=the distance such that points'A'and 'B'are of equal elevation. 'L' o 0o vo. Oo�oaf ��POINT'A' �POINT'B' \ \\\X NOT TO SCALE Figure 4.2.7— Rock Check Dam Volume II— Construction Stormwater Pollution Prevention -December 2014 4-77 BMP C208: Triangular Silt Dike (TSD) (Geotextile-Encased Check Dam) Purpose Triangular silt dikes may be used as check dams, for perimeter protection, for temporary soil stockpile protection, for drop inlet protection, or as a temporary interceptor dike. Conditions of use • May be used on soil or pavement with adhesive or staples. • TSDs have been used to build temporary: 1. sediment ponds; 2. diversion ditches; 3. concrete wash out facilities; 4. curbing; 5. water bars; 6. level spreaders; and, 7. berms. Design and Made of urethane foam sewn into a woven geosynthetic fabric. Installation It is triangular, 10 inches to 14 inches high in the center, with a 20-inch to Specifications 28-inch base. A 2—foot apron extends beyond both sides of the triangle along its standard section of 7 feet. A sleeve at one end allows attachment of additional sections as needed. • Install with ends curved up to prevent water from flowing around the ends. • The fabric flaps and check dam units are attached to the ground with wire staples. Wire staples should be No. 1 I gauge wire and should be 200 mm to 300 mm in length. • When multiple units are installed, the sleeve of fabric at the end of the unit shall overlap the abutting unit and be stapled. • Check dams should be located and installed as soon as construction will allow. • Check dams should be placed perpendicular to the flow of water. • When used as check dams, the leading edge must be secured with rocks, sandbags, or a small key slot and staples. • In the case of grass-lined ditches and swales, check dams and accumulated sediment shall be removed when the grass has matured sufficiently to protect the ditch or swale unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. Maintenance • Triangular silt dams shall be inspected for performance and sediment Volume II—Construction Stormwater Pollution Prevention-December 2014 4-78 Standards accumulation during and after each runoff producing rainfall. Sediment shall be removed when it reaches one half the height of the dam. • Anticipate submergence and deposition above the triangular silt dam and erosion from high flows around the edges of the dam. Immediately repair any damage or any undercutting of the dam. BMP C209: Outlet Protection Purpose Outlet protection prevents scour at conveyance outlets and minimizes the potential for downstream erosion by reducing the velocity of concentrated stormwater flows. Conditions of use Outlet protection is required at the outlets of all ponds,pipes, ditches, or other conveyances, and where runoff is conveyed to a natural or manmade drainage feature such as a stream, wetland, lake, or ditch. Design and The receiving channel at the outlet of a culvert shall be protected from Installation erosion by rock lining a minimum of 6 feet downstream and extending up Specifications the channel sides a minimum of 1—foot above the maximum tailwater elevation or 1-foot above the crown, whichever is higher. For large pipes (more than 18 inches in diameter), the outlet protection lining of the channel is lengthened to four times the diameter of the culvert. • Standard wingwalls, and tapered outlets and paved channels should also be considered when appropriate for permanent culvert outlet protection. (See WSDOT Hydraulic Manual, available through WSDOT Engineering Publications). • Organic or synthetic erosion blankets, with or without vegetation, are usually more effective than rock, cheaper, and easier to install. Materials can be chosen using manufacturer product specifications. ASTM test results are available for most products and the designer can choose the correct material for the expected flow. • With low flows, vegetation(including sod) can be effective. • The following guidelines shall be used for riprap outlet protection: 1. If the discharge velocity at the outlet is less than 5 fps (pipe slope less than 1 percent),use 2-inch to 8-inch riprap. Minimum thickness is 1-foot. 2. For 5 to 10 fps discharge velocity at the outlet(pipe slope less than 3 percent),use 24-inch to 48-inch riprap. Minimum thickness is 2 feet. 3. For outlets at the base of steep slope pipes (pipe slope greater than 10 percent), an engineered energy dissipater shall be used. • Filter fabric or erosion control blankets should always be used under riprap to prevent scour and channel erosion. Volume II—Construction Stormwater Pollution Prevention-December 2014 4-79 New pipe outfalls can provide an opportunity for low-cost fish habitat improvements. For example, an alcove of low-velocity water can be created by constructing the pipe outfall and associated energy dissipater back from the stream edge and digging a channel, over- widened to the upstream side, from the outfall. Overwintering juvenile and migrating adult salmonids may use the alcove as shelter during high flows. Bank stabilization, bioengineering, and habitat features may be required for disturbed areas. This work may require a HPA. See Volume V for more information on outfall system design. Maintenance • Inspect and repair as needed. Standards . Add rock as needed to maintain the intended function. • Clean energy dissipater if sediment builds up. BMP C220: Storm Drain Inlet Protection Purpose Storm drain inlet protection prevents coarse sediment from entering drainage systems prior to permanent stabilization of the disturbed area. Conditions of Use Use storm drain inlet protection at inlets that are operational before permanent stabilization of the disturbed drainage area. Provide protection for all storm drain inlets downslope and within 500 feet of a disturbed or construction area, unless conveying runoff entering catch basins to a sediment pond or trap. Also consider inlet protection for lawn and yard drains on new home construction. These small and numerous drains coupled with lack of gutters in new home construction can add significant amounts of sediment into the roof drain system. If possible delay installing lawn and yard drains until just before landscaping or cap these drains to prevent sediment from entering the system until completion of landscaping. Provide 18-inches of sod around each finished lawn and yard drain. Table 4.2.2 lists several options for inlet protection. All of the methods for storm drain inlet protection tend to plug and require a high frequency of maintenance. Limit drainage areas to one acre or less. Possibly provide emergency overflows with additional end-of-pipe treatment where stormwater ponding would cause a hazard. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-80 Table 4.2.2 Storm Drain Inlet Protection Applicable for Type of Inlet Emergency Paved/ Earthen Protection Overflow Surfaces Conditions of Use Drop Inlet Protection Excavated drop inlet Yes, Earthen Applicable for heavy flows. Easy protection temporary to maintain. Large area flooding will Requirement: 30' X 30'/acre occur Block and gravel drop Yes Paved or Earthen Applicablefor heavy concentrated inlet protection flows. Will not pond. Gravel and wire drop No Applicablefor heavy concentrated inlet protection flows. Will pond. Can withstand traffic. Catch basin filters Yes Paved or Earthen Frequent maintenance required. Curb Inlet Protection Curb inlet protection Small capacity Paved Used for sturdy, more compact with a wooden weir overflow installation. Block and gravel curb Yes Paved Sturdy, but limited filtration. inlet protection Culvert Inlet Protection Culvert inlet sediment 18 month expected life. trap Design and Excavated Drop Inlet Protection - An excavated impoundment around the Installation storm drain. Sediment settles out of the stormwater prior to entering the Specifications storm drain. • Provide a depth of 1-2 ft as measured from the crest of the inlet structure. • Slope sides of excavation no steeper than 2H:IV. • Minimum volume of excavation 35 cubic yards. • Shape basin to fit site with longest dimension oriented toward the longest inflow area. • Install provisions for draining to prevent standing water problems. • Clear the area of all debris. • Grade the approach to the inlet uniformly. • Drill weep holes into the side of the inlet. • Protect weep holes with screen wire and washed aggregate. • Seal weep holes when removing structure and stabilizing area. Volume II— Construction Stormwater Pollution Prevention -December 2014 4-81 • Build a temporary dike, if necessary, to the down slope side of the structure to prevent bypass flow. Block and Gravel Filter-A barrier formed around the storm drain inlet with standard concrete blocks and gravel. See Figure 4.2.8. • Provide a height of 1 to 2 feet above inlet. • Recess the first row 2-inches into the ground for stability. • Support subsequent courses by placing a 2x4 through the block opening. • Do not use mortar. • Lay some blocks in the bottom row on their side for dewatering the pool. • Place hardware cloth or comparable wire mesh with 1/2-inch openings over all block openings. • Place gravel just below the top of blocks on slopes of 2H:1 V or flatter. • An alternative design is a gravel donut. • Provide an inlet slope of 3H:1V. • Provide an outlet slope of 2H:IV. • Provide al-foot wide level stone area between the structure and the inlet. • Use inlet slope stones 3 inches in diameter or larger. • Use gravel '/2-to 3/4-inch at a minimum thickness of 1-foot for the outlet slope. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-82 Plan View A Drain O o Grate o �Qo ao ao0 0 ° 4� 6-0° 0 0 ado° oao0�0 v oo°DOo e DO' O oo Ooc, 0 � a�OooQ�Q ao0�41 00 o asOq�°,00 0o Concrete �0 ��oa oo Block g�4 ooeQe a 0` oLl ��oe�o O4 aOD°�O�o°o Gravel .O Backfill o 0 �DES 9 �00 00 ��°m00 0°oD o ��°oD °o"D o" °o"D �O 0 00 0 �ao04 Oo^ oo °aoOa�^/oo oa"O Oa�Oa oD°O � aD� DOS 0 �oo oa � �� Oo � O oDO Section A - A Concrete Block Wire Screen or Filter Fabric Gravel Backfill Overflow Water Ponding Height ° o o l a O 6O o� o Water) °�0� 000 Drop Inlet Notes: 1. Drop inlet sediment barriers are to be used for small,nearly level drainage areas.(less than 5%) 2. Excavate a basin of sufficient size adjacent to the drop inlet. 3.The top of the structure(ponding height)must be well below the ground elevation downslope to prevent runoff from bypassing the inlet.A temporary dike may be necessary on the downslope side of the structure. Figure 4.2.8- Block and Gravel Filter Gravel and Wire Mesh Filter- A gravel barrier placed over the top of the inlet. This structure does not provide an overflow. • Use a hardware cloth or comparable wire mesh with '/2-inch openings. • Use coarse aggregate. • Provide a height 1-foot or more, 18-inches wider than inlet on all sides. • Place wire mesh over the drop inlet so that the wire extends a minimum of 1-foot beyond each side of the inlet structure. • Overlap the strips if more than one strip of mesh is necessary. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-83 • Place coarse aggregate over the wire mesh. • Provide at least a 12-inch depth of gravel over the entire inlet opening and extend at least 18-inches on all sides. Catchbasin Filters—Use inserts designed by manufacturers for construction sites. The limited sediment storage capacity increases the amount of inspection and maintenance required, which may be daily for heavy sediment loads. To reduce maintenance requirements combine a catchbasin filter with another type of inlet protection. This type of inlet protection provides flow bypass without overflow and therefore may be a better method for inlets located along active rights-of-way. • Provides 5 cubic feet of storage. • Requires dewatering provisions. • Provides a high-flow bypass that will not clog under normal use at a construction site. • Insert the catchbasin filter in the catchbasin just below the grating. Curb Inlet Protection with Wooden Weir—Barrier formed around a curb inlet with a wooden frame and gravel. • Use wire mesh with 1/2-inch openings. • Use extra strength filter cloth. • Construct a frame. • Attach the wire and filter fabric to the frame. • Pile coarse washed aggregate against wire/fabric. • Place weight on frame anchors. Block and Gravel Curb Inlet Protection—Barrier formed around a curb inlet with concrete blocks and gravel. See Figure 4.2.9. • Use wire mesh with 1/2-inch openings. • Place two concrete blocks on their sides abutting the curb at either side of the inlet opening. These are spacer blocks. • Place a 2x4 stud through the outer holes of each spacer block to align the front blocks. • Place blocks on their sides across the front of the inlet and abutting the spacer blocks. • Place wire mesh over the outside vertical face. • Pile coarse aggregate against the wire to the top of the barrier. Curb and Gutter Sediment Barrier—Sandbag or rock berm(riprap and aggregate) 3 feet high and 3 feet wide in a horseshoe shape. See Figure 4.2.10. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-84 • Construct a horseshoe shaped berm, faced with coarse aggregate if using riprap, 3 feet high and 3 feet wide, at least 2 feet from the inlet. • Construct a horseshoe shaped sedimentation trap on the outside of the berm sized to sediment trap standards for protecting a culvert inlet. Maintenance • Inspect catch basin filters frequently, especially after storm events. Standards Clean and replace clogged inserts. For systems with clogged stone filters: pull away the stones from the inlet and clean or replace. An alternative approach would be to use the clogged stone as fill and put fresh stone around the inlet. • Do not wash sediment into storm drains while cleaning. Spread all excavated material evenly over the surrounding land area or stockpile and stabilize as appropriate. Approved as Ecology has approved products as able to meet the requirements of BMP Equivalent C220. The products did not pass through the Technology Assessment Protocol—Ecology(TAPE)process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at http://www.ecy.wa. og v/pro,grams/wq/stormwater/newtech/equivalent.html Volume II—Construction Stormwater Pollution Prevention -December 2014 4-85 Plan View Back of Sidewalk A Catch Basin 2x4 Wood Stud Back of Curb Concrete Block Curb Inlet `o� o Oo- ° a o�'°. °. oolY� oa °a °• Oo � bpdo o•.o� �0 p8O �.�mLH 000O°p. �Ua�b O°°• p °p• p°p° `O p• ° °op• g ° op�°• ` ao o oaO�g: o o oo �•o a g'o 4op.oQo�o°oop. 9° o Qo°�CQ °q°�o•Qo° op°o.oQ�.�°o °Oo•.D� o�. �o °° a�Q oaa ate•. 4 °o a a:° q o s oa.b�q •8�0° a Oo oa SJo 0 Wire Screen or Filter Fabric A Concrete Block Section A - A ( Drain Gravel 20mm) %"Drain Gravel (20mm) Ponding Height Concrete Block Overflow °g4 0 a Curb Inlet Wire Screen or Filter Fabric �\ Catch Basin \\' 4 Wood Stud (100x50 Timber Stud) \j NOTES: 1. Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment, where water can pond and allow sediment to separate from runoff. 2. Barrier shall allow for overflow from severe storm event. 3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately. Figure 4.2.9—Block and Gravel Curb Inlet Protection Volume II—Construction Stormwater Pollution Prevention -December 2014 4-86 Plan View Back of Sidewalk Burlap Sacks to Catch Basin Overlap onto Curb Curb Inlet Back of Curb RUNOFF RUNOFF SPILLWAY Gravel Filled Sandbags Stacked Tightly NOTES: 1.Place curb type sediment barriers on gently sloping street segments,where water can pond and allow sediment to separate from runoff. 2. Sandbags of either burlap or woven'geotextile'fabric,are filled with gravel,layered and packed tightly. 3.Leave a one sandbag gap in the top row to provide a spillway for overflow. 4.Inspect barriers and remove sediment after each storm event.Sediment and gravel must be removed from the traveled way immediately. Figure 4.2.10—Curb and Gutter Barrier Volume II— Construction Stormwater Pollution Prevention -December 2014 4-87 BMP C231: Brush Barrier Purpose The purpose of brush barriers is to reduce the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use • Brush barriers may be used downslope of all disturbed areas of less than one-quarter acre. Brush barriers are not intended to treat concentrated flows, nor are they intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to a sediment pond. The only circumstance in which overland flow can be treated solely by a brush barrier, rather than by a sediment pond, is when the area draining to the barrier is small. Brush barriers should only be installed on contours. Design and • Height 2 feet(minimum) to 5 feet(maximum). Installation . Width 5 feet at base (minimum) to 15 feet(maximum). Specifications • Filter fabric (geotextile) may be anchored over the brush berm to enhance the filtration ability of the barrier. Ten-ounce burlap is an adequate alternative to filter fabric. • Chipped site vegetation, composted mulch, or wood-based mulch (hog fuel) can be used to construct brush barriers. • A 100 percent biodegradable installation can be constructed using 10- ounce burlap held in place by wooden stakes. Figure 4.2.11 depicts a typical brush barrier. Maintenance • There shall be no signs of erosion or concentrated runoff under or Standards around the barrier. If concentrated flows are bypassing the barrier, it must be expanded or augmented by toed-in filter fabric. The dimensions of the barrier must be maintained. If required,drape filter fabric over brush and secure in 4"x4" min.trench with compacted backfill. Anchor downhill edge of - filter fabric with stakes, sandbags,or equivalent. �*C 2'Min.Height Min.5'wide brush barrier with max.6"diameter woody debris. Alternatively topsoil strippings may be used to form the barrier. Figure 4.2.11 —Brush Barrier Volume II—Construction Stormwater Pollution Prevention -December 2014 4-88 BMP C232: Gravel Filter Berm Purpose A gravel filter berm is constructed on rights-of-way or traffic areas within a construction site to retain sediment by using a filter berm of gravel or crushed rock. Conditions of Use Where a temporary measure is needed to retain sediment from rights-of- way or in traffic areas on construction sites. Design and Berm material shall be 3/4 to 3 inches in size, washed well-grade gravel Installation or crushed rock with less than 5 percent fines. Specifications Spacing of berms: — Every 300 feet on slopes less than 5 percent — Every 200 feet on slopes between 5 percent and 10 percent — Every 100 feet on slopes greater than 10 percent • Berm dimensions: — 1 foot high with 3H:1 V side slopes — 8 linear feet per 1 cfs runoff based on the I0-year, 24-hour design storm Maintenance • Regular inspection is required. Sediment shall be removed and filter Standards material replaced as needed. BMP C233: Silt Fence Purpose Use of a silt fence reduces the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. See Figure 4.2.12 for details on silt fence construction. Conditions of Use Silt fence may be used downslope of all disturbed areas. • Silt fence shall prevent soil carried by runoff water from going beneath, through, or over the top of the silt fence, but shall allow the water to pass through the fence. • Silt fence is not intended to treat concentrated flows, nor is it intended to treat substantial amounts of overland flow. Convey any concentrated flows through the drainage system to a sediment pond. • Do not construct silt fences in streams or use in V-shaped ditches. Silt fences do not provide an adequate method of silt control for anything deeper than sheet or overland flow. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-89 Joints in filter fabric shall be spliced at posts. Use staples,wire rings or 2"x2"by 14 Ga.wire or equivalent to attach fabric to posts equivalent, if standard r� strength fabric used I Filter fabric II E CV II 6'max Minimum 4"x4"trench - .E N J Backfill trench with native soil' I �� Post spacing may be increased or 3/4"-1.5"washed gravel to 8'if wire backing is used 2"x2"wood posts,steel fence posts,or equivalent Figure 4.2.12—Silt Fence Design and • Use in combination with sediment basins or other BMPs. Installation Maximum slope steepness (normal (perpendicular) to fence line) Specifications 1H:IV. Maximum sheet or overland flow path length to the fence of 100 feet. • Do not allow flows greater than 0.5 cfs. The geotextile used shall meet the following standards. All geotextile properties listed below are minimum average roll values (i.e., the test result for any sampled roll in a lot shall meet or exceed the values shown in Table 4.2.3): Table 4.2.3 Geotextile Standards Polymeric Mesh AOS 0.60 mm maximum for slit film woven(#30 sieve).0.30 (ASTM D4751) mm maximum for all other geotextile types(#50 sieve). 0.15 mm minimum for all fabric types(#100 sieve). Water Permittivity 0.02 sec minimum (ASTM D4491) Grab Tensile Strength 180 lbs.Minimum for extra strength fabric. (ASTM D4632) 100 lbs minimum for standard strength fabric. Grab Tensile Strength 30%maximum (ASTM D4632) Ultraviolet Resistance 70%minimum (ASTM D4355) • Support standard strength fabrics with wire mesh, chicken wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the strength of the fabric. Silt fence materials are available that have synthetic mesh backing attached. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-90 • Filter fabric material shall contain ultraviolet ray inhibitors and stabilizers to provide a minimum of six months of expected usable construction life at a temperature range of 0°F. to 120°F. • One-hundred percent biodegradable silt fence is available that is strong, long lasting, and can be left in place after the project is completed, if permitted by local regulations. • Refer to Figure 4.2.12 for standard silt fence details. Include the following standard Notes for silt fence on construction plans and specifications: 1. The contractor shall install and maintain temporary silt fences at the locations shown in the Plans. 2. Construct silt fences in areas of clearing, grading, or drainage prior to starting those activities. 3. The silt fence shall have a 2-feet min. and a 2'/2-feet max. height above the original ground surface. 4. The filter fabric shall be sewn together at the point of manufacture to form filter fabric lengths as required. Locate all sewn seams at support posts. Alternatively, two sections of silt fence can be overlapped, provided the Contractor can demonstrate, to the satisfaction of the Engineer, that the overlap is long enough and that the adjacent fence sections are close enough together to prevent silt laden water from escaping through the fence at the overlap. 5. Attach the filter fabric on the up-slope side of the posts and secure with staples, wire, or in accordance with the manufacturer's recommendations. Attach the filter fabric to the posts in a manner that reduces the potential for tearing. 6. Support the filter fabric with wire or plastic mesh, dependent on the properties of the geotextile selected for use. If wire or plastic mesh is used, fasten the mesh securely to the up-slope side of the posts with the filter fabric up-slope of the mesh. 7. Mesh support, if used, shall consist of steel wire with a maximum mesh spacing of 2-inches, or a prefabricated polymeric mesh. The strength of the wire or polymeric mesh shall be equivalent to or greater than 180 lbs. grab tensile strength. The polymeric mesh must be as resistant to the same level of ultraviolet radiation as the filter fabric it supports. 8. Bury the bottom of the filter fabric 4-inches min. below the ground surface. Backfill and tamp soil in place over the buried portion of the filter fabric, so that no flow can pass beneath the fence and scouring cannot occur. When wire or polymeric back-up support Volume II—Construction Stormwater Pollution Prevention -December 2014 4-91 mesh is used, the wire or polymeric mesh shall extend into the ground 3-inches min. 9. Drive or place the fence posts into the ground 18-inches min. A 12—inch min. depth is allowed if topsoil or other soft subgrade soil is not present and 18-inches cannot be reached. Increase fence post min. depths by 6 inches if the fence is located on slopes of 3H:1 V or steeper and the slope is perpendicular to the fence. If required post depths cannot be obtained, the posts shall be adequately secured by bracing or guying to prevent overturning of the fence due to sediment loading. 10. Use wood, steel or equivalent posts. The spacing of the support posts shall be a maximum of 6-feet. Posts shall consist of either: • Wood with dimensions of 2-inches by 2-inches wide min. and a 3-feet min. length. Wood posts shall be free of defects such as knots, splits, or gouges. • No. 6 steel rebar or larger. • ASTM A 120 steel pipe with a minimum diameter of 1-inch. • U, T, L, or C shape steel posts with a minimum weight of 1.35 lbs./ft. • Other steel posts having equivalent strength and bending resistance to the post sizes listed above. 11. Locate silt fences on contour as much as possible, except at the ends of the fence, where the fence shall be turned uphill such that the silt fence captures the runoff water and prevents water from flowing around the end of the fence. 12. If the fence must cross contours, with the exception of the ends of the fence, place gravel check dams perpendicular to the back of the fence to minimize concentrated flow and erosion. The slope of the fence line where contours must be crossed shall not be steeper than 3H:1 V. • Gravel check dams shall be approximately 1-foot deep at the back of the fence. Gravel check dams shall be continued perpendicular to the fence at the same elevation until the top of the check dam intercepts the ground surface behind the fence. • Gravel check dams shall consist of crushed surfacing base course, gravel backfill for walls, or shoulder ballast. Gravel check dams shall be located every 10 feet along the fence where the fence must cross contours. • Refer to Figure 4.2.13 for slicing method details. Silt fence installation using the slicing method specifications: Volume II—Construction Stormwater Pollution Prevention -December 2014 4-92 1. The base of both end posts must be at least 2-to 4-inches above the top of the filter fabric on the middle posts for ditch checks to drain properly. Use a hand level or string level, if necessary, to mark base points before installation. 2. Install posts 3-to 4-feet apart in critical retention areas and 6-to 7- feet apart in standard applications. 3. Install posts 24-inches deep on the downstream side of the silt fence, and as close as possible to the filter fabric, enabling posts to support the filter fabric from upstream water pressure. 4. Install posts with the nipples facing away from the filter fabric. 5. Attach the filter fabric to each post with three ties, all spaced within the top 8-inches of the filter fabric. Attach each tie diagonally 45 degrees through the filter fabric, with each puncture at least 1-inch vertically apart. Each tie should be positioned to hang on a post nipple when tightening to prevent sagging. 6. Wrap approximately 6-inches of fabric around the end posts and secure with 3 ties. 7. No more than 24-inches of a 36-inch filter fabric is allowed above ground level. Compact the soil immediately next to the filter fabric with the front wheel of the tractor, skid steer, or roller exerting at least 60 pounds per square inch. Compact the upstream side first and then each side twice for a total of four trips. Check and correct the silt fence installation for any deviation before compaction. Use a flat-bladed shovel to tuck fabric deeper into the ground if necessary. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-93 Ponding height POST SPACING: max.24- 7'max.on open runs 4'max.on pooling areas ------------ ---------------Top of Fabric 117177177 Bit Attach fabric to upstream side of post [O�8• FLOW Drive over each side of POST DEPTH: silt fence 2 to 4 times As much below ground with device exerting as fabric above ground 6o p.s.1.or greater 100%cwnpactloj' te0%compaCrall Diagonal attachment doubles strength. /\\\71 /—\/ �/�\ ATTACHMENT DETAILS: /�\ •Gather fabric at posts,if needed. �\\\ P P top•Utilize three ties per oat,all within t 8"of fabric. �\\\ •Position each lie diagonally,puncturing holes vertically ✓/\\/\\/\�/ \� a minimum of 1•apart. \ \ •Hang each tie on a post nipple and tighten secrsely. No more than 24"of a 36"fabric Use cable ties(50lbs)or sort wife. is allowed above ground. Roll of silt fence t� Operation Post installed after Li 01 compaction Fabric Oabove ground Silt Fence M. 200-300mm Horizontal chisel point Slicing blade (76 mm width) (1 S mm width) Completed Installation Vibratory plow is not acceptable because of horizontal compaction Figure 4.2.13—Silt Fence Installation by Slicing Method Maintenance • Repair any damage immediately. Standards • Intercept and convey all evident concentrated flows uphill of the silt fence to a sediment pond. • Check the uphill side of the fence for signs of the fence clogging and acting as a barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace the fence or remove the trapped sediment. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-94 • Remove sediment deposits when the deposit reaches approximately one-third the height of the silt fence, or install a second silt fence. • Replace filter fabric that has deteriorated due to ultraviolet breakdown. BMP C234: Vegetated Strip Puy^pose Vegetated strips reduce the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use • Vegetated strips may be used downslope of all disturbed areas. • Vegetated strips are not intended to treat concentrated flows, nor are they intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to a sediment pond. The only circumstance in which overland flow can be treated solely by a strip, rather than by a sediment pond, is when the following criteria are met (see Table 4.2.4): Table 4.2.4 Contributing Drainage Area for Vegetated Strips Average Contributing Average Contributing area Max Contributing area Sloe Percent Sloe area Flow path Length 1.5H:1 V or flatter 67%or flatter 100 feet 2H:1 V or flatter 50%or flatter 115 feet 4H:1V or flatter 25%or flatter 150 feet 6H:1 V or flatter 16.7%or flatter 200 feet 1 OH:1 V or flatter 10%or flatter 250 feet Design and The vegetated strip shall consist of a minimum of a 25-foot flowpath Installation length continuous strip of dense vegetation with topsoil. Grass- Specifications covered, landscaped areas are generally not adequate because the volume of sediment overwhelms the grass. Ideally, vegetated strips shall consist of undisturbed native growth with a well-developed soil that allows for infiltration of runoff. • The slope within the strip shall not exceed 4H:IV. • The uphill boundary of the vegetated strip shall be delineated with clearing limits. Maintenance Any areas damaged by erosion or construction activity shall be Standards seeded immediately and protected by mulch. • If more than 5 feet of the original vegetated strip width has had vegetation removed or is being eroded, sod must be installed. • If there are indications that concentrated flows are traveling across the buffer, surface water controls must be installed to reduce the flows Volume II—Construction Stormwater Pollution Prevention -December 2014 4-95 entering the buffer, or additional perimeter protection must be installed. BMP C235: Wattles Purpose Wattles are temporary erosion and sediment control barriers consisting of straw, compost, or other material that is wrapped in biodegradable tubular plastic or similar encasing material. They reduce the velocity and can spread the flow of rill and sheet runoff, and can capture and retain sediment. Wattles are typically 8 to 10 inches in diameter and 25 to 30 feet in length. Wattles are placed in shallow trenches and staked along the contour of disturbed or newly constructed slopes. See Figure 4.2.14 for typical construction details. WSDOT Standard Plan I-30.30-00 also provides information on Wattles (hM2://www.wsdot.wa.gov/Design/Standards/Plans.htm#Section Conditions of Use Use wattles: • In disturbed areas that require immediate erosion protection. • On exposed soils during the period of short construction delays, or over winter months. • On slopes requiring stabilization until permanent vegetation can be established. • The material used dictates the effectiveness period of the wattle. Generally, Wattles are typically effective for one to two seasons. • Prevent rilling beneath wattles by properly entrenching and abutting wattles together to prevent water from passing between them. Design Criteria Install wattles perpendicular to the flow direction and parallel to the slope contour. • Narrow trenches should be dug across the slope on contour to a depth of 3-to 5-inches on clay soils and soils with gradual slopes. On loose soils, steep slopes, and areas with high rainfall, the trenches should be dug to a depth of 5-to 7- inches, or 1/2 to 2/3 of the thickness of the wattle. • Start building trenches and installing wattles from the base of the slope and work up. Spread excavated material evenly along the uphill slope and compacted using hand tamping or other methods. • Construct trenches at intervals of 10-to 25-feet depending on the steepness of the slope, soil type, and rainfall. The steeper the slope the closer together the trenches. • Install the wattles snugly into the trenches and abut tightly end to end. Do not overlap the ends. • Install stakes at each end of the wattle, and at 4-foot centers along entire length of wattle. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-96 • If required, install pilot holes for the stakes using a straight bar to drive holes through the wattle and into the soil. • Wooden stakes should be approximately 3/4 x 3/4 x 24 inches min. Willow cuttings or 3/8-inch rebar can also be used for stakes. • Stakes should be driven through the middle of the wattle, leaving 2 to 3 inches of the stake protruding above the wattle. Maintenance Wattles may require maintenance to ensure they are in contact with Standards soil and thoroughly entrenched, especially after significant rainfall on steep sandy soils. Volume II—Construction Stormwater Pollution Prevention -December 2014 4-97 T-4' Straw Rolls Must \�\ Be Placed Along AjVA Slope Contours j j Adjacent rolls shall \ tightly abut \y Spacing Dependson Soil Slope Steepness e and /\//\\i Sediment,organic matter, \\\\/ and native seeds are /\ captured behind the rolls. 3"-5"(75-125mm) (200-250mm) \ Live Stake �,\\ 1" X 1" Stake not to scale (25 x 25mm) NOTE: 1.Straw roll installation requires the placement and secure staking of the roll in a trench,Y-5"(75-125mm) deep,dug on contour. runoff must not be allowed to run under or around roll. Figure 4.2.14—Wattles Volume II— Construction Stormwater Pollution Prevention -December 2014 4-98 Stormwater Pollution Prevention Plan Appendix C — Alternative BMPs The following includes a list of possible alternative BMPs for each of the 12 elements not described in the main SWPPP text. This list can be referenced in the event a BMP for a specific element is not functioning as designed and an alternative BMP needs to be implemented. Element#1 -Mark Clearing Limits BMP C 102 Buffer Zones Element#2 -Establish Construction Access BMP C106 Wheel Wash Element#3 - Control Flow Rates BMP C203 Water Bars BMP C235 Wattles BMP C240 Sediment Trap BMP C241 Sediment Pond Element#4 -Install Sediment Controls BMP C231 Brush Barrier BMP C232 Gravel Filter Berm BMP C234 Vegetated Strip BMP C235 Wattles BMP C240 Sediment Trap BMP C241 Sediment Pond Element#5 - Stabilize Soils BMP C 122 Nets & Blankets BMP C 124 Sodding BMP C 126 Polyacrylamides for Soil Erosion Protection BMP C130 Surface Roughening BMP C 131 Gradient Terraces Element#6 - Protect Slopes BMP C 122 Nets & Blankets BMP C130 Surface Roughening BMP C 131 Gradient Terraces Element#7—Protect Drain Inlets Element#8 - Stabilize Channels and Outlets BMP C 122 Nets & Blankets BMP C202 Channel Lining BMP C208 Triangular Silt Dike 24 Stormwater Pollution Prevention Plan Element#9—Control Pollutants BMP C 154 Concrete Washout Area Element#10 - Control Dewatering BMP C203 Water Bars BMP C206 Level Spreader BMP C236 Vegetated Filtration Element#11 —Maintain BMP's Element#12 —Manage the Project Element#13—Protect Low Impact Development BMP C 102 Buffer Zones BMP C208 Triangular Silt Dike BMP C231 Brush Barrier BMP C234 Vegetated Strip 25 Stormwater Pollution Prevention Plan Appendix D — General Permit 26 Issuance Date: November 18, 2015 Effective Date: January 1, 2016 Expiration Date: December 31,2020 CONSTRUCTION STORMWATER GENERAL PERMIT National Pollutant Discharge Elimination System (NPDES) and State Waste Discharge General Permit for Stormwater Discharges Associated with Construction Activity State of Washington Department of Ecology Olympia, Washington 98504 In compliance with the provisions of Chapter 90.48 Revised Code of Washington (State of Washington Water Pollution Control Act) and Title 33 United States Code, Section 1251 et seq. The Federal Water Pollution Control Act (The Clean Water Act) Until this permit expires, is modified, or revoked, Permittees that have properly obtained coverage under this general permit are authorized to discharge ui accordance with the special and general conditions that follow. Hea hbr R. Bartlett Wate,-Quality Program Manager Washington State Department of Ecology TABLE OF CONTENTS LISTOF TABLES...........................................................................................................................3 SUMMARY OF PERMIT REPORT SUBMITTALS.....................................................................4 SPECIAL CONDITIONS................................................................................................................5 S 1. PERMIT COVERAGE........................................................................................................5 S2. APPLICATION REQUIREMENTS ...................................................................................8 S3. COMPLIANCE WITH STANDARDS.............................................................................12 S4. MONITORING REQUIREMENTS, BENCHMARKS, AND REPORTINGTRIGGERS ................................................................................................13 S5. REPORTING AND RECORDKEEPING REQUIREMENTS .........................................20 S6. PERMIT FEES...................................................................................................................23 S7. SOLID AND LIQUID WASTE DISPOSAL ....................................................................23 S8. DISCHARGES TO 303(d) OR TMDL WATERBODIES................................................23 S9. STORMWATER POLLUTION PREVENTION PLAN...................................................27 S 10. NOTICE OF TERMINATION.........................................................................................37 GENERALCONDITIONS ...........................................................................................................38 G1. DISCHARGE VIOLATIONS ...........................................................................................38 G2. SIGNATORY REQUIREMENTS.....................................................................................38 G3. RIGHT OF INSPECTION AND ENTRY.........................................................................39 G4. GENERAL PERMIT MODIFICATION AND REVOCATION......................................39 G5. REVOCATION OF COVERAGE UNDER THE PERMIT .............................................39 G6. REPORTING A CAUSE FOR MODIFICATION............................................................40 G7. COMPLIANCE WITH OTHER LAWS AND STATUTES.............................................40 G8. DUTY TO REAPPLY.......................................................................................................40 G9. TRANSFER OF GENERAL PERMIT COVERAGE.......................................................41 G10. REMOVED SUBSTANCES .............................................................................................41 G11. DUTY TO PROVIDE INFORMATION...........................................................................41 G12. OTHER REQUIREMENTS OF 40 CFR...........................................................................41 G 13. ADDITIONAL MONITORING........................................................................................41 G14. PENALTIES FOR VIOLATING PERMIT CONDITIONS .............................................41 G15. UPSET...............................................................................................................................42 G16. PROPERTY RIGHTS........................................................................................................42 Construction Stormwater General Permit Page 2 G17. DUTY TO COMPLY ........................................................................................................42 G18. TOXIC POLLUTANTS.....................................................................................................42 G19. PENALTIES FOR TAMPERING.....................................................................................43 G20. REPORTING PLANNED CHANGES .............................................................................43 G21. REPORTING OTHER INFORMATION..........................................................................43 G22. REPORTING ANTICIPATED NON-COMPLIANCE.....................................................43 G23. REQUESTS TO BE EXCLUDED FROM COVERAGE UNDER THE PERMIT..........44 G24. APPEALS ..........................................................................................................................44 G25. SEVERABILITY...............................................................................................................44 G26. BYPASS PROHIBITED....................................................................................................44 APPENDIX A—DEFINITIONS...................................................................................................47 APPENDIX B—ACRONYMS .....................................................................................................55 LIST OF TABLES Table 1: Summary of Required Submittals................................................................................... 4 Table 2: Summary of Required On-site Documentation............................................................... 4 Table 3: Summary of Primary Monitoring Requirements .......................................................... 15 Table 4: Monitoring and Reporting Requirements ..................................................................... 17 Table 5: Turbidity, Fine Sediment& Phosphorus Sampling and Limits for 303(d)-Listed Waters.................................................................................................... 25 Table 6: pH Sampling and Limits for 303(d)-Listed Waters...................................................... 26 Construction Stormwater General Permit Page 3 SUMMARY OF PERMIT REPORT SUBMITTALS Refer to the Special and General Conditions within this permit for additional submittal requirements. Appendix A provides a list of definitions. Appendix B provides a list of acronyms. Table 1: Summary of Required Submittals Permit Submittal Frequency First Submittal Date Section S5.A and High Turbidity/Transparency Phone As Necessary Within 24 hours S8 Reporting S5.B Discharge Monitoring Report Monthly* Within 15 days following the end of each month S5.F and Noncompliance Notification — As necessary Within 24-hours S8 Telephone Notification S5.F Noncompliance Notification — As necessary Within 5 Days of non- Written Report compliance S9.0 Request for Chemical Treatment As necessary Written approval from Form Ecology is required prior to using chemical treatment (with the exception of dry ice or CO2 to adjust pH) G2 Notice of Change in Authorization As necessary G6 Permit Application for Substantive As necessary Changes to the Discharge G8 Application for Permit Renewal 1/permit cycle No later than 180 days before expiration G9 Notice of Permit Transfer As necessary G20 Notice of Planned Changes As necessary G22 Reporting Anticipated Non- As necessary compliance SPECIAL NOTE: *Permittees must submit electronic Discharge Monitoring Reports(DMRs)to the Washington State Department of Ecology monthly,regardless of site discharge,for the full duration of permit coverage.Refer to Section S5.13 of this General Permit for more specific information regarding DMRs. Table 2: Summary of Required On-site Documentation Document Title Permit Conditions Permit Coverage Letter See Conditions S2, S5 Construction Stormwater General Permit See Conditions S2, S5 Site Log Book See Conditions S4, S5 Stormwater Pollution Prevention Plan (SWPPP) See Conditions S9, S5 Construction Stormwater General Permit Page 4 SPECIAL CONDITIONS S1. PERMIT COVERAGE A. Permit Area This Construction Stormwater General Permit(CSWGP) covers all areas of Washington State, except for federal operators and Indian Country as specified in Special Condition S 1.E.3. B. Operators Required to Seek Coverage Under this General Permit: 1. Operators of the following construction activities are required to seek coverage under this CSWGP: a. Clearing, grading and/or excavation that results in the disturbance of one or more acres (including off-site disturbance acreage authorized in S 1.C.2) and discharges stormwater to surface waters of the State; and clearing, grading and/or excavation on sites smaller than one acre that are part of a larger common plan of development or sale, if the common plan of development or sale will ultimately disturb one acre or more and discharge stormwater to surface waters of the State. i. This includes forest practices (including,but not limited to, class IV conversions) that are part of a construction activity that will result in the disturbance of one or more acres, and discharge to surface waters of the State (that is, forest practices that prepare a site for construction activities); and b. Any size construction activity discharging stormwater to waters of the State that the Washington State Department of Ecology(Ecology): i. Determines to be a significant contributor of pollutants to waters of the State of Washington. ii. Reasonably expects to cause a violation of any water quality standard. 2. Operators of the following activities are not required to seek coverage under this CSWGP (unless specifically required under Special Condition S1.B.l.b. above): a. Construction activities that discharge all stormwater and non-stormwater to ground water, sanitary sewer, or combined sewer, and have no point source discharge to either surface water or a storm sewer system that drains to surface waters of the State. b. Construction activities covered under an Erosivity Waiver(Special Condition S2.C). c. Routine maintenance that is performed to maintain the original line and grade, hydraulic capacity, or original purpose of a facility. Construction Stormwater General Permit Page 5 C. Authorized Discharges: 1. Stormwater Associated with Construction Activity. Subject to compliance with the terms and conditions of this permit, Permittees are authorized to discharge stormwater associated with construction activity to surface waters of the State or to a storm sewer system that drains to surface waters of the State. (Note that"surface waters of the State"may exist on a construction site as well as off site; for example, a creek running through a site.) 2. Stormwater Associated with Construction Support Activity. This permit also authorizes stormwater discharge from support activities related to the permitted construction site (for example, an on-site portable rock crusher, off-site equipment staging yards, material storage areas, borrow areas, etc.)provided: a. The support activity relates directly to the permitted construction site that is required to have an NPDES permit; and b. The support activity is not a commercial operation serving multiple unrelated construction projects, and does not operate beyond the completion of the construction activity; and c. Appropriate controls and measures are identified in the Stormwater Pollution Prevention Plan (SWPPP) for the discharges from the support activity areas. 3. Non-Stormwater Discharges. The categories and sources of non-stormwater discharges identified below are authorized conditionally,provided the discharge is consistent with the terms and conditions of this permit: a. Discharges from fire-fighting activities. b. Fire hydrant system flushing. c. Potable water, including uncontaminated water line flushing. d. Hydrostatic test water. e. Uncontaminated air conditioning or compressor condensate. f. Uncontaminated ground water or spring water. g. Uncontaminated excavation dewatering water(in accordance with S9.D.10). h. Uncontaminated discharges from foundation or footing drains. i. Uncontaminated water used to control dust. Permittees must minimize the amount of dust control water used. j. Routine external building wash down that does not use detergents. k. Landscape irrigation water. The SWPPP must adequately address all authorized non-stormwater discharges, except for discharges from fire-fighting activities, and must comply with Special Condition S3. Construction Stormwater General Permit Page 6 At a minimum, discharges from potable water(including water line flushing), fire hydrant system flushing, and pipeline hydrostatic test water must undergo the following: dechlorination to a concentration of 0.1 parts per million (ppm) or less, and pH adjustment to within 6.5 — 8.5 standard units (su), if necessary. D. Prohibited Discharges: The following discharges to waters of the State, including ground water, are prohibited. 1. Concrete wastewater. 2. Wastewater from washout and clean-up of stucco,paint, form release oils, curing compounds and other construction materials. 3. Process wastewater as defined by 40 Code of Federal Regulations (CFR) 122.2 (see Appendix A of this permit). 4. Slurry materials and waste from shaft drilling, including process wastewater from shaft drilling for construction of building, road, and bridge foundations unless managed according to Special Condition S9.D.9.j. 5. Fuels, oils, or other pollutants used in vehicle and equipment operation and maintenance. 6. Soaps or solvents used in vehicle and equipment washing. 7. Wheel wash wastewater, unless managed according to Special Condition S9.D.9. 8. Discharges from dewatering activities, including discharges from dewatering of trenches and excavations, unless managed according to Special Condition S9.D.10. E. Limits on Coverage Ecology may require any discharger to apply for and obtain coverage under an individual permit or another more specific general permit. Such alternative coverage will be required when Ecology determines that this CSWGP does not provide adequate assurance that water quality will be protected, or there is a reasonable potential for the project to cause or contribute to a violation of water quality standards. The following stormwater discharges are not covered by this permit: 1. Post-construction stormwater discharges that originate from the site after completion of construction activities and the site has undergone final stabilization. 2. Non-point source silvicultural activities such as nursery operations, site preparation, reforestation and subsequent cultural treatment, thinning, prescribed burning, pest and fire control, harvesting operations, surface drainage, or road construction and maintenance, from which there is natural runoff as excluded in 40 CFR Subpart 122. 3. Stormwater from any federal operator. Construction Stormwater General Permit Page 7 4. Stormwater from facilities located on"Indian Country" as defined in 18 U.S.C.§1151, except portions of the Puyallup Reservation as noted below. Indian Country includes: a. All land within any Indian Reservation notwithstanding the issuance of any patent, and, including rights-of-way running through the reservation. This includes all federal, tribal, and Indian and non-Indian privately owned land within the reservation. b. All off-reservation Indian allotments, the Indian titles to which have not been extinguished, including rights-of-way running through the same. c. All off-reservation federal trust lands held for Native American Tribes. Puyallup Exception: Following the Puyallup Tribes of Indians Land Settlement Act of 1989, 25 U.S.C. §1773; the permit does apply to land within the Puyallup Reservation except for discharges to surface water on land held in trust by the federal government. 5. Stormwater from any site covered under an existing NPDES individual permit in which stormwater management and/or treatment requirements are included for all stormwater discharges associated with construction activity. 6. Stormwater from a site where an applicable Total Maximum Daily Load(TMDL) requirement specifically precludes or prohibits discharges from construction activity. S2. APPLICATION REQUIREMENTS A. Permit Application Forms 1. Notice of Intent Form/Timeline a. Operators of new or previously unpermitted construction activities must submit a complete and accurate permit application (Notice of Intent, or NOI)to Ecology. b. Operators must apply using the electronic application form(NOI) available on Ecology's website http://www.ecy.wa.goy/programs/wq/stormwater/ construction/index.html. Permittees unable to submit electronically(for example, those who do not have an internet connection)must contact Ecology to request a waiver and obtain instructions on how to obtain a paper NOI. Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 Construction Stormwater General Permit Page 8 c. The operator must submit the NOI at least 60 days before discharging stormwater from construction activities and must submit it on or before the date of the first public notice (see Special Condition S2.B below for details). The 30- day public comment period begins on the publication date of the second public notice. Unless Ecology responds to the complete application in writing, based on public comments, or any other relevant factors, coverage under the general permit will automatically commence on the thirty-first day following receipt by Ecology of a completed NOI, or the issuance date of this permit, whichever is later; unless Ecology specifies a later date in writing as required by WAC173- 226-200(2). d. If an applicant intends to use a Best Management Practice (BMP) selected on the basis of Special Condition S9.C.4 ("demonstrably equivalent"BMPs), the applicant must notify Ecology of its selection as part of the NOI. In the event the applicant selects BMPs after submission of the NOI, it must provide notice of the selection of an equivalent BMP to Ecology at least 60 days before intended use of the equivalent BMP. e. Permittees must notify Ecology regarding any changes to the information provided on the NOI by submitting an updated NOI. Examples of such changes include, but are not limited to: i. Changes to the Permittee's mailing address, ii. Changes to the on-site contact person information, and iii. Changes to the area/acreage affected by construction activity. f. Applicants must notify Ecology if they are aware of contaminated soils and/or groundwater associated with the construction activity. Provide detailed information with the NOI (as known and readily available) on the nature and extent of the contamination (concentrations, locations, and depth), as well as pollution prevention and/or treatment BMPs proposed to control the discharge of soil and/or groundwater contaminants in stormwater. Examples of such detail may include,but are not limited to: i. List or table of all known contaminants with laboratory test results showing concentration and depth, ii. Map with sample locations, iii. Temporary Erosion and Sediment Control (TESC)plans, iv. Related portions of the Stormwater Pollution Prevention Plan (SWPPP) that address the management of contaminated and potentially contaminated construction stormwater and dewatering water, V. Dewatering plan and/or dewatering contingency plan. Construction Stormwater General Permit Page 9 2. Transfer of Coverage Form The Permittee can transfer current coverage under this permit to one or more new operators, including operators of sites within a Common Plan of Development, provided the Permittee submits a Transfer of Coverage Form in accordance with General Condition G9. Transfers do not require public notice. B. Public Notice For new or previously unpermitted construction activities, the applicant must publish a public notice at least one time each week for two consecutive weeks, at least 7 days apart, in a newspaper with general circulation in the county where the construction is to take place. The notice must contain: 1. A statement that"The applicant is seeking coverage under the Washington State Department of Ecology's Construction Stormwater NPDES and State Waste Discharge General Permit". 2. The name, address and location of the construction site. 3. The name and address of the applicant. 4. The type of construction activity that will result in a discharge (for example, residential construction, commercial construction, etc.), and the number of acres to be disturbed. 5. The name of the receiving water(s) (that is, the surface water(s)to which the site will discharge), or, if the discharge is through a storm sewer system, the name of the operator of the system. 6. The statement: "Any persons desiring to present their views to the Washington State Department of Ecology regarding this application, or interested in Ecology's action on this application, may notify Ecology in writing no later than 30 days of the last date of publication of this notice. Ecology reviews public comments and considers whether discharges from this project would cause a measurable change in receiving water quality, and, if so,whether the project is necessary and in the overriding public interest according to Tier II antidegradation requirements under WAC 173-201A-320. Comments can be submitted to: Department of Ecology, PO Box 47696, Olympia, Washington 98504-7696 Attn: Water Quality Program, Construction Stormwater." Construction Stormwater General Permit Page 10 C. Erosivity Waiver Construction site operators may qualify for an erosivity waiver from the CSWGP if the following conditions are met: 1. The site will result in the disturbance of fewer than 5 acres and the site is not a portion of a common plan of development or sale that will disturb 5 acres or greater. 2. Calculation of Erosivity"R"Factor and Regional Timeframe: a. The project's rainfall erosivity factor ("R"Factor) must be less than 5 during the period of construction activity, as calculated(see the CSWGP homepage http://www.ccy.wa.goy/programs/wg/stonnwater/construction/index.html for a link to the EPA's calculator and step by step instructions on computing the "R" Factor in the EPA Erosivity Waiver Fact Sheet). The period of construction activity starts when the land is first disturbed and ends with final stabilization. In addition: b. The entire period of construction activity must fall within the following timeframes: i. For sites west of the Cascades Crest: June 15 — September 15. ii. For sites east of the Cascades Crest, excluding the Central Basin: June 15 —October 15. iii. For sites east of the Cascades Crest,within the Central Basin: no additional timeframe restrictions apply. The Central Basin is defined as the portions of Eastern Washington with mean annual precipitation of less than 12 inches. For a map of the Central Basin(Average Annual Precipitation Region 2), refer to hqp://www.ecy.wa.goy/programs/wq/stonnwater/ constiruction/resourcesguidance.html. 3. Construction site operators must submit a complete Erosivity Waiver certification form at least one week before disturbing the land. Certification must include statements that the operator will: a. Comply with applicable local stormwater requirements; and b. Implement appropriate erosion and sediment control BMPs to prevent violations of water quality standards. 4. This waiver is not available for facilities declared significant contributors of pollutants as defined in Special Condition S I.B.Lb. or for any size construction activity that could reasonably expect to cause a violation of any water quality standard as defined in Special Condition S 1.13.Lb.ii. 5. This waiver does not apply to construction activities which include non- stormwater discharges listed in Special Condition S 1.C.3. Construction Stormwater General Permit Page 11 6. If construction activity extends beyond the certified waiver period for any reason, the operator must either: a. Recalculate the rainfall erosivity"R" factor using the original start date and a new projected ending date and, if the "R" factor is still under 5 and the entire project falls within the applicable regional timeframe in Special Condition S2.C.2.b, complete and submit an amended waiver certification form before the original waiver expires; or b. Submit a complete permit application to Ecology in accordance with Special Condition S2.A and B before the end of the certified waiver period. S3. COMPLIANCE WITH STANDARDS A. Discharges must not cause or contribute to a violation of surface water quality standards (Chapter 173-201A WAC), ground water quality standards (Chapter 173-200 WAC), sediment management standards (Chapter 173-204 WAC), and human health-based criteria in the National Toxics Rule (40 CFR Part 131.36). Discharges not in compliance with these standards are not authorized. B. Prior to the discharge of stormwater and non-stormwater to waters of the State, the Permittee must apply all known, available, and reasonable methods of prevention, control, and treatment(AKART). This includes the preparation and implementation of an adequate SWPPP, with all appropriate BMPs installed and maintained in accordance with the SWPPP and the terms and conditions of this permit. C. Ecology presumes that a Permittee complies with water quality standards unless discharge monitoring data or other site-specific information demonstrates that a discharge causes or contributes to a violation of water quality standards, when the Permittee complies with the following conditions. The Permittee must fully: 1. Comply with all permit conditions, including planning, sampling, monitoring, reporting, and recordkeeping conditions. 2. Implement stormwater BMPs contained in stormwater management manuals published or approved by Ecology, or BMPs that are demonstrably equivalent to BMPs contained in stormwater technical manuals published or approved by Ecology, including the proper selection, implementation, and maintenance of all applicable and appropriate BMPs for on-site pollution control. (For purposes of this section, the stormwater manuals listed in Appendix 10 of the Phase I Municipal Stormwater Permit are approved by Ecology.) D. Where construction sites also discharge to ground water, the ground water discharges must also meet the terms and conditions of this CSWGP. Permittees who discharge to ground water through an injection well must also comply with any applicable requirements of the Underground Injection Control (UIC)regulations, Chapter 173-218 WAC. Construction Stormwater General Permit Page 12 S4. MONITORING REQUIREMENTS, BENCHMARKS,AND REPORTING TRIGGERS A. Site Log Book The Permittee must maintain a site log book that contains a record of the implementation of the SWPPP and other permit requirements, including the installation and maintenance of BMPs, site inspections, and stormwater monitoring. B. Site Inspections The Permittee's site inspections must include all areas disturbed by construction activities, all BMPs, and all stormwater discharge points under the Permittee's operational control. (See Special Conditions S4.B.3 and BA below for detailed requirements of the Permittee's Certified Erosion and Sediment Control Lead [CESCL].) Construction sites one acre or larger that discharge stormwater to surface waters of the State must have site inspections conducted by a certified CESCL. Sites less than one acre may have a person without CESCL certification conduct inspections. 1. The Permittee must examine stormwater visually for the presence of suspended sediment, turbidity, discoloration, and oil sheen. The Permittee must evaluate the effectiveness of BMPs and determine if it is necessary to install, maintain, or repair BMPs to improve the quality of stormwater discharges. Based on the results of the inspection, the Permittee must correct the problems identified by: a. Reviewing the SWPPP for compliance with Special Condition S9 and making appropriate revisions within 7 days of the inspection. b. Immediately beginning the process of fully implementing and maintaining appropriate source control and/or treatment BMPs as soon as possible, addressing the problems no later than within 10 days of the inspection. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when an extension is requested by a Permittee within the initial 10-day response period. c. Documenting BMP implementation and maintenance in the site log book. 2. The Permittee must inspect all areas disturbed by construction activities, all BMPs, and all stormwater discharge points at least once every calendar week and within 24 hours of any discharge from the site. (For purposes of this condition, individual discharge events that last more than one day do not require daily inspections. For example, if a stormwater pond discharges continuously over the course of a week, only one inspection is required that week.) The Permittee may reduce the inspection frequency for temporarily stabilized, inactive sites to once every calendar month. Construction Stormwater General Permit Page 13 3. The Permittee must have staff knowledgeable in the principles and practices of erosion and sediment control. The CESCL(sites one acre or more) or inspector (sites less than one acre) must have the skills to assess the: a. Site conditions and construction activities that could impact the quality of stormwater, and b. Effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. 4. The SWPPP must identify the CESCL or inspector,who must be present on site or on-call at all times. The CESCL must obtain this certification through an approved erosion and sediment control training program that meets the minimum training standards established by Ecology(see BMP C 160 in the manual referred to in Special Condition S9.C.1 and 2). 5. The Permittee must summarize the results of each inspection in an inspection report or checklist and enter the report/checklist into, or attach it to, the site log book. At a minimum, each inspection report or checklist must include: a. Inspection date and time. b. Weather information, the general conditions during inspection and the approximate amount of precipitation since the last inspection, and precipitation within the last 24 hours. c. A summary or list of all implemented BMPs, including observations of all erosion/sediment control structures or practices. d. A description of the locations: i. Of BMPs inspected; ii. Of BMPs that need maintenance and why; iii. Of BMPs that failed to operate as designed or intended; and iv. Where additional or different BMPs are needed, and why. e. A description of stormwater discharged from the site. The Permittee must note the presence of suspended sediment, turbidity, discoloration, and oil sheen, as applicable. f. Any water quality monitoring performed during inspection. g. General comments and notes, including a brief description of any BMP repairs, maintenance or installations made following the inspection. h. A summary report and a schedule of implementation of the remedial actions that the Permittee plans to take if the site inspection indicates that the site is out of compliance. The remedial actions taken must meet the requirements of the SWPPP and the permit. Construction Stormwater General Permit Page 14 i. The name, title, and signature of the person conducting the site inspection, a phone number or other reliable method to reach this person, and the following statement: "I certify that this report is true, accurate, and complete to the best of my knowledge and belief." Table 3: Summary of Primary Monitoring Requirements Size of Soil Weekly Site Weekly Weekly Weekly pH CESCL Disturbancel Inspections Sampling w/ Sampling w/ Sampling2 Required for Turbidity Transparency Inspections? Meter Tube Sites that disturb Required Not Required Not Required Not Required No less than 1 acre, but are part of a larger Common Plan of Development Sites that disturb 1 Required Sampling Required — Required Yes acre or more, but either method' fewer than 5 acres Sites that disturb 5 Required Required Not Required' Required Yes acres or more ' Soil disturbance is calculated by adding together all areas that will be affected by construction activity. Construction activity means clearing,grading,excavation,and any other activity that disturbs the surface of the land,including ingress/egress from the site. 2 If construction activity results in the disturbance of 1 acre or more,and involves significant concrete work(1,000 cubic yards of poured over the life of a project)or the use of recycled concrete or engineered soils(soil amendments including but not limited to Portland cement-treated base[CTB],cement kiln dust[CKD], or fly ash),and stormwater from the affected area drains to surface waters of the State or to a storm sewer stormwater collection system that drains to other surface waters of the State,the Permittee must conduct pH sampling in accordance with Special Condition S4.13. 3 Sites with one or more acres,but fewer than 5 acres of soil disturbance,must conduct turbidity or transparency sampling in accordance with Special Condition S4.C. ' Sites equal to or greater than 5 acres of soil disturbance must conduct turbidity sampling using a turbidity meter in accordance with Special Condition S4.C. Construction Stormwater General Permit Page 15 C. Turbidity/Transparency Sampling Requirements 1. Sampling Methods a. If construction activity involves the disturbance of 5 acres or more, the Permittee must conduct turbidity sampling per Special Condition S4.C. b. If construction activity involves 1 acre or more but fewer than 5 acres of soil disturbance, the Permittee must conduct either transparency sampling or turbidity sampling per Special Condition S4.C. 2. Sampling Frequency a. The Permittee must sample all discharge points at least once every calendar week when stormwater(or authorized non-stormwater) discharges from the site or enters any on-site surface waters of the state (for example, a creek running through a site); sampling is not required on sites that disturb less than an acre. b. Samples must be representative of the flow and characteristics of the discharge. c. Sampling is not required when there is no discharge during a calendar week. d. Sampling is not required outside of normal working hours or during unsafe conditions. e. If the Permittee is unable to sample during a monitoring period, the Permittee must include a brief explanation in the monthly Discharge Monitoring Report (DMR). £ Sampling is not required before construction activity begins. g. The Permittee may reduce the sampling frequency for temporarily stabilized, inactive sites to once every calendar month. 3. Sampling Locations a. Sampling is required at all points where stormwater associated with construction activity(or authorized non-stormwater) is discharged off site, including where it enters any on-site surface waters of the state (for example, a creek running through a site). b. The Permittee may discontinue sampling at discharge points that drain areas of the project that are fully stabilized to prevent erosion. c. The Permittee must identify all sampling point(s) on the SWPPP site map and clearly mark these points in the field with a flag, tape, stake or other visible marker. d. Sampling is not required for discharge that is sent directly to sanitary or combined sewer systems. Construction Stormwater General Permit Page 16 e. The Permittee may discontinue sampling at discharge points in areas of the project where the Permittee no longer has operational control of the construction activity. 4. Sampling and Analysis Methods a. The Permittee performs turbidity analysis with a calibrated turbidity meter (turbidimeter) either on site or at an accredited lab. The Permittee must record the results in the site log book in nephelometric turbidity units (NTUs). b. The Permittee performs transparency analysis on site with a 13/4-inch-diameter, 60-centimeter(cm)-long transparency tube. The Permittee will record the results in the site log book in centimeters (cm). Table 4: Monitoring and Reporting Requirements Parameter Unit Analytical Method Sampling Benchmark Phone Frequency Value Reporting Trigger Value Turbidity NTU SM2130 Weekly, if 25 NTUs 250 NTUs discharging Transparency cm Manufacturer Weekly, if 33 cm 6 cm instructions, or discharging Ecology guidance 5. Turbidity/Transparency Benchmark Values and Reporting Triggers The benchmark value for turbidity is 25 NTUs or less. The benchmark value for transparency is 33 centimeters (cm). Note: Benchmark values do not apply to discharges to segments of water bodies on Washington State's 303(d) list (Category 5) for turbidity, fine sediment, or phosphorus; these discharges are subject to a numeric effluent limit for turbidity. Refer to Special Condition S8 for more information. a. Turbidity 26—249 NTUs, or Transparency 32 —7 cm: If the discharge turbidity is 26 to 249 NTUs; or if discharge transparency is less than 33 cm, but equal to or greater than 6 cm, the Permittee must: i. Review the SWPPP for compliance with Special Condition S9 and make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. ii. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible, addressing the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. Construction Stormwater General Permit Page 17 iii. Document BMP implementation and maintenance in the site log book. b. Turbidity 250 NTUs or greater, or Transparency 6 cm or less: If a discharge point's turbidity is 250 NTUs or greater, or if discharge transparency is less than or equal to 6 cm, the Permittee must complete the reporting and adaptive management process described below. i. Telephone or submit an electronic report to the applicable Ecology Region's Environmental Report Tracking System (ERTS) number (or through Ecology's Water Quality Permitting Portal [WQWebPortal] — Permit Submittals when the form is available)within 24 hours, in accordance with Special Condition S5.A. • Central Region (Okanogan, Chelan, Douglas, Kittitas, Yakima, Klickitat, Benton): (509) 575-2490 • Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400 • Northwest Region (Kitsap, Snohomish, Island, King, San Juan, Skagit, Whatcom): (425) 649-7000 • Southwest Region (Grays Harbor, Lewis, Mason, Thurston, Pierce, Clark, Cowlitz, Skamania, Wahkiakum, Clallam, Jefferson, Pacific): (360) 407-6300 Links to these numbers and the ERTS reporting page are located on the following web site: http://www.ecy.wa.gov/programs/wq/stonnwater/construction/index.html. ii. Review the SWPPP for compliance with Special Condition S9 and make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. iii. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible, addressing the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. iv. Document BMP implementation and maintenance in the site log book. V. Sample discharges daily until: a) Turbidity is 25 NTUs (or lower); or b) Transparency is 33 cm(or greater); or Construction Stormwater General Permit Page 18 c) The Permittee has demonstrated compliance with the water quality limit for turbidity: 1) No more than 5 NTUs over background turbidity, if background is less than 50 NTUs, or 2) No more than 10% over background turbidity, if background is 50 NTUs or greater; or d) The discharge stops or is eliminated. D. pH Sampling Requirements— Significant Concrete Work or Engineered Soils If construction activity results in the disturbance of 1 acre or more, and involves significant concrete work(significant concrete work means greater than 1000 cubic yards poured concrete used over the life of a project) or the use of recycled concrete or engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD], or fly ash), and stormwater from the affected area drains to surface waters of the State or to a storm sewer system that drains to surface waters of the State, the Permittee must conduct pH sampling as set forth below. Note: In addition, discharges to segments of water bodies on Washington State's 303(d) list (Category 5) for high pH are subject to a numeric effluent limit for pH; refer to Special Condition S8. 1. For sites with significant concrete work, the Permittee must begin the pH sampling period when the concrete is first poured and exposed to precipitation, and continue weekly throughout and after the concrete pour and curing period, until stormwater pH is in the range of 6.5 to 8.5 (su). 2. For sites with recycled concrete, the Permittee must begin the weekly pH sampling period when the recycled concrete is first exposed to precipitation and must continue until the recycled concrete is fully stabilized and stormwater pH is in the range of 6.5 to 8.5 (su). 3. For sites with engineered soils, the Permittee must begin the pH sampling period when the soil amendments are first exposed to precipitation and must continue until the area of engineered soils is fully stabilized. 4. During the applicable pH monitoring period defined above, the Permittee must obtain a representative sample of stormwater and conduct pH analysis at least once per week. 5. The Permittee must sample pH in the sediment trap/pond(s) or other locations that receive stormwater runoff from the area of significant concrete work or engineered soils before the stormwater discharges to surface waters. 6. The benchmark value for pH is 8.5 standard units. Anytime sampling indicates that pH is 8.5 or greater, the Permittee must either: Construction Stormwater General Permit Page 19 a. Prevent the high pH water(8.5 or above) from entering storm sewer systems or surface waters; or b. If necessary, adjust or neutralize the high pH water until it is in the range of pH 6.5 to 8.5 (su)using an appropriate treatment BMP such as carbon dioxide (CO2) sparging or dry ice. The Permittee must obtain written approval from Ecology before using any form of chemical treatment other than CO2 sparging or dry ice. 7. The Permittee must perform pH analysis on site with a calibrated pH meter,pH test kit, or wide range pH indicator paper. The Permittee must record pH sampling results in the site log book. S5. REPORTING AND RECORDKEEPING REQUIREMENTS A. High Turbidity Reporting Anytime sampling performed in accordance with Special Condition S4.0 indicates turbidity has reached the 250 NTUs or more (or transparency less than or equal to 6 cm) high turbidity reporting level, the Permittee must either call the applicable Ecology Region's Environmental Report Tracking System (ERTS) number by phone within 24 hours of analysis or submit an electronic ERTS report (or submit an electronic report through Ecology's Water Quality Permitting Portal (WQWebPortal)—Permit Submittals when the form is available). See the CSWGP web site for links to ERTS and the WQWebPortal: http://www.ecy.wa.gov/programs/wq/stonnwater/construction/ index.html. Also, see phone numbers in Special Condition S4.C.5.b.i. B. Discharge Monitoring Reports (DMRs) Permittees required to conduct water quality sampling in accordance with Special Conditions S4.0 (Turbidity/Transparency), S4.D (pH), S8 (303[d]/TMDL sampling), and/or G13 (Additional Sampling) must submit the results to Ecology. Permittees must submit monitoring data using Ecology's WQWebDMR web application accessed through Ecology's Water Quality Permitting Portal. To find out more information and to sign up for WQWebDMR go to: http://www.ecy.wa.gov/pro rg ams/ wq//permits/paris/portal.html. Permittees unable to submit electronically(for example, those who do not have an internet connection)must contact Ecology to request a waiver and obtain instructions on how to obtain a paper copy DMR at: Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 Permittees who obtain a waiver not to use WQWebDMR must use the forms provided to them by Ecology; submittals must be mailed to the address above. Permittees shall Construction Stormwater General Permit Page 20 submit DMR forms to be received by Ecology within 15 days following the end of each month. If there was no discharge during a given monitoring period, all Permittees must submit a DMR as required with"no discharge" entered in place of the monitoring results. DMRs are required for the full duration of permit coverage (from issuance date to termination). For more information, contact Ecology staff using information provided at the following web site: www.ecy.wa.gov/programs/wq/permits/paris/contacts.html. C. Records Retention The Permittee must retain records of all monitoring information(site log book, sampling results, inspection reports/checklists, etc.), Stormwater Pollution Prevention Plan, copy of the permit coverage letter(including Transfer of Coverage documentation), and any other documentation of compliance with permit requirements for the entire life of the construction project and for a minimum of three years following the termination of permit coverage. Such information must include all calibration and maintenance records, and records of all data used to complete the application for this permit. This period of retention must be extended during the course of any unresolved litigation regarding the discharge of pollutants by the Permittee or when requested by Ecology. D. Recording Results For each measurement or sample taken, the Permittee must record the following information: 1. Date, place, method, and time of sampling or measurement. 2. The first and last name of the individual who performed the sampling or measurement. 3. The date(s)the analyses were performed. 4. The first and last name of the individual who performed the analyses. 5. The analytical techniques or methods used. 6. The results of all analyses. E. Additional Monitoring by the Permittee If the Permittee monitors any pollutant more frequently than required by this permit using test procedures specified by Special Condition S4 of this permit, the results of this monitoring must be included in the calculation and reporting of the data submitted in the Permittee's DMR. F. Noncompliance Notification In the event the Permittee is unable to comply with any part of the terms and conditions of this permit, and the resulting noncompliance may cause a threat to human health or the environment(such as but not limited to spills of fuels or other materials, catastrophic pond or slope failure, and discharges that violate water quality standards), or exceed Construction Stormwater General Permit Page 21 numeric effluent limitations (see S8. Discharges to 303(d) or TMDL Waterbodies), the Permittee must, upon becoming aware of the circumstance: 1. Notify Ecology within 24-hours of the failure to comply by calling the applicable Regional office ERTS phone number(refer to Special Condition S4.C.5.b.i. or www.ecy.wa ,Lov/programs/wg/stortnwater/construction/turbidity.html for Regional ERTS phone numbers). 2. Immediately take action to prevent the discharge/pollution, or otherwise stop or correct the noncompliance, and, if applicable, repeat sampling and analysis of any noncompliance immediately and submit the results to Ecology within five (5) days of becoming aware of the violation. 3. Submit a detailed written report to Ecology within five (5) days, of the time the Permittee becomes aware of the circumstances,unless requested earlier by Ecology. The report must be submitted using Ecology's Water Quality Permitting Portal (WQWebPortal) - Permit Submittals,unless a waiver from electronic reporting has been granted according to S5.B. The report must contain a description of the noncompliance, including exact dates and times, and if the noncompliance has not been corrected, the anticipated time it is expected to continue; and the steps taken or planned to reduce, eliminate, and prevent reoccurrence of the noncompliance. The Permittee must report any unanticipated bypass and/or upset that exceeds any effluent limit in the permit in accordance with the 24-hour reporting requirement contained in 40 C.F.R. 122.41(1)(6). Compliance with these requirements does not relieve the Permittee from responsibility to maintain continuous compliance with the terms and conditions of this permit or the resulting liability for failure to comply. Upon request of the Permittee, Ecology may waive the requirement for a written report on a case-by- case basis, if the immediate notification is received by Ecology within 24 hours. G. Access to Plans and Records 1. The Permittee must retain the following permit documentation(plans and records) on site, or within reasonable access to the site, for use by the operator or for on-site review by Ecology or the local jurisdiction: a. General Permit b. Permit Coverage Letter c. Stormwater Pollution Prevention Plan (SWPPP) d. Site Log Book 2. The Permittee must address written requests for plans and records listed above (Special Condition S5.G.1) as follows: Construction Stormwater General Permit Page 22 a. The Permittee must provide a copy of plans and records to Ecology within 14 days of receipt of a written request from Ecology. b. The Permittee must provide a copy of plans and records to the public when requested in writing. Upon receiving a written request from the public for the Permittee's plans and records, the Permittee must either: i. Provide a copy of the plans and records to the requester within 14 days of a receipt of the written request; or ii. Notify the requester within 10 days of receipt of the written request of the location and times within normal business hours when the plans and records may be viewed; and provide access to the plans and records within 14 days of receipt of the written request; or iii. Within 14 days of receipt of the written request, the Permittee may submit a copy of the plans and records to Ecology for viewing and/or copying by the requester at an Ecology office, or a mutually agreed location. If plans and records are viewed and/or copied at a location other than at an Ecology office, the Permittee will provide reasonable access to copying services for which a reasonable fee may be charged. The Permittee must notify the requester within 10 days of receipt of the request where the plans and records may be viewed and/or copied. S6. PERMIT FEES The Permittee must pay permit fees assessed by Ecology. Fees for stormwater discharges covered under this permit are established by Chapter 173-224 WAC. Ecology continues to assess permit fees until the permit is terminated in accordance with Special Condition S 10 or revoked in accordance with General Condition G5. S7. SOLID AND LIQUID WASTE DISPOSAL The Permittee must handle and dispose of solid and liquid wastes generated by construction activity, such as demolition debris, construction materials, contaminated materials, and waste materials from maintenance activities, including liquids and solids from cleaning catch basins and other stormwater facilities, in accordance with: A. Special Condition S3, Compliance with Standards B. WAC 173-216-110 C. Other applicable regulations S8. DISCHARGES TO 303(d) OR TMDL WATERBODIES A. Sampling and Numeric Effluent Limits For Certain Discharges to 303(d)-listed Waterbodies Construction Stormwater General Permit Page 23 1. Permittees who discharge to segments of waterbodies listed as impaired by the State of Washington under Section 303(d) of the Clean Water Act for turbidity, fine sediment, high pH, or phosphorus, must conduct water quality sampling according to the requirements of this section, and Special Conditions S4.C.2.b-f and S4.C.3.b-d, and must comply with the applicable numeric effluent limitations in S&C and S&D. 2. All references and requirements associated with Section 303(d) of the Clean Water Act mean the most current listing by Ecology of impaired waters (Category 5)that exists on January 1, 2016, or the date when the operator's complete permit application is received by Ecology, whichever is later. B. Limits on Coverage for New Discharges to TMDL or 303(d)-listed Waters Operators of construction sites that discharge to a TMDL or 303(d)-listed waterbody are not eligible for coverage under this permit unless the operator: 1. Prevents exposing stormwater to pollutants for which the waterbody is impaired, and retains documentation in the SWPPP that details procedures taken to prevent exposure on site; or 2. Documents that the pollutants for which the waterbody is impaired are not present at the site, and retains documentation of this finding within the SWPPP; or 3. Provides Ecology with data indicating the discharge is not expected to cause or contribute to an exceedance of a water quality standard, and retains such data on site with the SWPPP. The operator must provide data and other technical information to Ecology that sufficiently demonstrate: a. For discharges to waters without an EPA-approved or-established TMDL, that the discharge of the pollutant for which the water is impaired will meet in- stream water quality criteria at the point of discharge to the waterbody; or b. For discharges to waters with an EPA-approved or-established TMDL, that there is sufficient remaining wasteload allocation in the TMDL to allow construction stormwater discharge and that existing dischargers to the waterbody are subject to compliance schedules designed to bring the waterbody into attainment with water quality standards. Operators of construction sites are eligible for coverage under this permit if Ecology issues permit coverage based upon an affirmative determination that the discharge will not cause or contribute to the existing impairment. C. Sampling and Numeric Effluent Limits for Discharges to Water Bodies on the 303(d) List for Turbidity, Fine Sediment, or Phosphorus 1. Permittees who discharge to segments of water bodies on the 303(d) list (Category 5) for turbidity, fine sediment, or phosphorus must conduct turbidity sampling in accordance with Special Condition S4.C.2 and comply with either of the numeric effluent limits noted in Table 5 below. Construction Stormwater General Permit Page 24 2. As an alternative to the 25 NTUs effluent limit noted in Table 5 below (applied at the point where stormwater [or authorized non-stormwater] is discharged off-site), Permittees may choose to comply with the surface water quality standard for turbidity. The standard is: no more than 5 NTUs over background turbidity when the background turbidity is 50 NTUs or less, or no more than a 10% increase in turbidity when the background turbidity is more than 50 NTUs. In order to use the water quality standard requirement, the sampling must take place at the following locations: a. Background turbidity in the 303(d)-listed receiving water immediately upstream (upgradient) or outside the area of influence of the discharge. b. Turbidity at the point of discharge into the 303(d)-listed receiving water, inside the area of influence of the discharge. 3. Discharges that exceed the numeric effluent limit for turbidity constitute a violation of this permit. 4. Permittees whose discharges exceed the numeric effluent limit shall sample discharges daily until the violation is corrected and comply with the non- compliance notification requirements in Special Condition S5.F. Table 5: Turbidity, Fine Sediment & Phosphorus Sampling and Limits for 303(d)-Listed Waters Parameter identified Parameter Unit Analytical Sampling Numeric Effluent in 303(d) listing Sampled Method Frequency Limit' • Turbidity Turbidity NTU SM2130 Weekly, if 25 NTUs, at the • Fine Sediment discharging point where • Phosphorus stormwater is discharged from the site; OR In compliance with the surface water quality standard for turbidity(S8.C.2.a) 'Permittees subject to a numeric effluent limit for turbidity may, at their discretion, choose either numeric effluent limitation based on site-specific considerations including, but not limited to, safety, access and convenience. D. Discharges to Water Bodies on the 303(d) List for High pH 1. Permittees who discharge to segments of water bodies on the 303(d) list (Category 5) for high pH must conduct pH sampling in accordance with the table below, and comply with the numeric effluent limit of pH 6.5 to 8.5 su(Table 6). Construction Stormwater General Permit Page 25 Table 6: pH Sampling and Limits for 303(d)-Listed Waters Parameter identified in Parameter Analytical Sampling Numeric Effluent 303(d) listing Sampled/Units Method Frequency Limit High pH pH /Standard pH meter Weekly, if In the range of 6.5 Units discharging —8.5 2. At the Permittee's discretion, compliance with the limit shall be assessed at one of the following locations: a. Directly in the 303(d)-listed waterbody segment, inside the immediate area of influence of the discharge; or b. Alternatively, the Permittee may measure pH at the point where the discharge leaves the construction site, rather than in the receiving water. 3. Discharges that exceed the numeric effluent limit for pH (outside the range of 6.5 — 8.5 su) constitute a violation of this permit. 4. Permittees whose discharges exceed the numeric effluent limit shall sample discharges daily until the violation is corrected and comply with the non- compliance notification requirements in Special Condition S5.F. E. Sampling and Limits for Sites Discharging to Waters Covered by a TMDL or Another Pollution Control Plan 1. Discharges to a waterbody that is subject to a Total Maximum Daily Load (TMDL) for turbidity, fine sediment, high pH, or phosphorus must be consistent with the TMDL. Refer to hqp://www.ecy.wa.gov/programs/wq/tmdl/ TMDLsbyWria/TMDLbyWria.html for more information on TMDLs. a. Where an applicable TMDL sets specific waste load allocations or requirements for discharges covered by this permit, discharges must be consistent with any specific waste load allocations or requirements established by the applicable TMDL. i. The Permittee must sample discharges weekly or as otherwise specified by the TMDL to evaluate compliance with the specific waste load allocations or requirements. ii. Analytical methods used to meet the monitoring requirements must conform to the latest revision of the Guidelines Establishing Test Procedures for the Analysis of Pollutants contained in 40 CFR Part 136. Turbidity and pH methods need not be accredited or registered unless conducted at a laboratory which must otherwise be accredited or registered. b. Where an applicable TMDL has established a general waste load allocation for construction stormwater discharges,but has not identified specific requirements, Construction Stormwater General Permit Page 26 compliance with Special Conditions S4 (Monitoring) and S9 (SWPPPs) will constitute compliance with the approved TMDL. c. Where an applicable TMDL has not specified a waste load allocation for construction stormwater discharges,but has not excluded these discharges, compliance with Special Conditions S4 (Monitoring) and S9 (SWPPPs) will constitute compliance with the approved TMDL. d. Where an applicable TMDL specifically precludes or prohibits discharges from construction activity, the operator is not eligible for coverage under this permit. 2. Applicable TMDL means a TMDL for turbidity, fine sediment, high pH, or phosphorus that is completed and approved by EPA before January 1, 2016, or before the date the operator's complete permit application is received by Ecology, whichever is later. TMDLs completed after the operator's complete permit application is received by Ecology become applicable to the Permittee only if they are imposed through an administrative order by Ecology, or through a modification of permit coverage. S9. STORMWATER POLLUTION PREVENTION PLAN The Permittee must prepare and properly implement an adequate Stormwater Pollution Prevention Plan(SWPPP) for construction activity in accordance with the requirements of this permit beginning with initial soil disturbance and until final stabilization. A. The Permittee's SWPPP must meet the following objectives: 1. To implement best management practices (BMPs)to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. To prevent violations of surface water quality, ground water quality, or sediment management standards. 3. To control peak volumetric flow rates and velocities of stormwater discharges. B. General Requirements 1. The SWPPP must include a narrative and drawings. All BMPs must be clearly referenced in the narrative and marked on the drawings. The SWPPP narrative must include documentation to explain and justify the pollution prevention decisions made for the project. Documentation must include: a. Information about existing site conditions (topography, drainage, soils, vegetation, etc.). b. Potential erosion problem areas. c. The 13 elements of a SWPPP in Special Condition S9.13.1-13, including BMPs used to address each element. Construction Stormwater General Permit Page 27 d. Construction phasing/sequence and general BMP implementation schedule. e. The actions to be taken if BMP performance goals are not achieved—for example, a contingency plan for additional treatment and/or storage of stormwater that would violate the water quality standards if discharged. f. Engineering calculations for ponds, treatment systems, and any other designed structures. 2. The Permittee must modify the SWPPP if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is, or would be, ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The Permittee must then: a. Review the SWPPP for compliance with Special Condition S9 and make appropriate revisions within 7 days of the inspection or investigation. b. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible, addressing the problems no later than 10 days from the inspection or investigation. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when an extension is requested by a Permittee within the initial 10-day response period. c. Document BMP implementation and maintenance in the site log book. The Permittee must modify the SWPPP whenever there is a change in design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the State. C. Stormwater Best Management Practices (BMPs) BMPs must be consistent with: 1. Stormwater Management Manual for Western Washington(most current approved edition at the time this permit was issued), for sites west of the crest of the Cascade Mountains; or 2. Stormwater Management Manual for Eastern Washington (most current approved edition at the time this permit was issued), for sites east of the crest of the Cascade Mountains; or 3. Revisions to the manuals listed in Special Condition S9.C.1. &2., or other stormwater management guidance documents or manuals which provide an equivalent level of pollution prevention, that are approved by Ecology and incorporated into this permit in accordance with the permit modification requirements of WAC 173-226-230; or Construction Stormwater General Permit Page 28 4. Documentation in the SWPPP that the BMPs selected provide an equivalent level of pollution prevention, compared to the applicable Stormwater Management Manuals, including: a. The technical basis for the selection of all stormwater BMPs (scientific, technical studies, and/or modeling) that support the performance claims for the BMPs being selected. b. An assessment of how the selected BMP will satisfy AKART requirements and the applicable federal technology-based treatment requirements under 40 CFR part 125.3. D. SWPPP—Narrative Contents and Requirements The Permittee must include each of the 13 elements below in Special Condition S9.D.1-13 in the narrative of the SWPPP and implement them unless site conditions render the element unnecessary and the exemption from that element is clearly justified in the SWPPP. 1. Preserve Vegetation/Mark Clearing Limits a. Before beginning land-disturbing activities, including clearing and grading, clearly mark all clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the construction area. b. Retain the duff layer, native topsoil, and natural vegetation in an undisturbed state to the maximum degree practicable. 2. Establish Construction Access a. Limit construction vehicle access and exit to one route, if possible. b. Stabilize access points with a pad of quarry spalls, crushed rock, or other equivalent BMPs, to minimize tracking sediment onto roads. c. Locate wheel wash or tire baths on site, if the stabilized construction entrance is not effective in preventing tracking sediment onto roads. d. If sediment is tracked off site, clean the affected roadway thoroughly at the end of each day, or more frequently as necessary(for example, during wet weather). Remove sediment from roads by shoveling, sweeping, or pickup and transport of the sediment to a controlled sediment disposal area. e. Conduct street washing only after sediment removal in accordance with Special Condition S9.D.2.d. Control street wash wastewater by pumping back on site or otherwise preventing it from discharging into systems tributary to waters of the State. 3. Control Flow Rates a. Protect properties and waterways downstream of development sites from erosion and the associated discharge of turbid waters due to increases in the Construction Stormwater General Permit Page 29 velocity and peak volumetric flow rate of stormwater runoff from the project site, as required by local plan approval authority. b. Where necessary to comply with Special Condition S9.D.3.a, construct stormwater retention or detention facilities as one of the first steps in grading. Assure that detention facilities function properly before constructing site improvements (for example, impervious surfaces). c. If permanent infiltration ponds are used for flow control during construction, protect these facilities from siltation during the construction phase. 4. Install Sediment Controls The Permittee must design, install and maintain effective erosion controls and sediment controls to minimize the discharge of pollutants. At a minimum, the Permittee must design, install and maintain such controls to: a. Construct sediment control BMPs (sediment ponds, traps, filters, infiltration facilities, etc.) as one of the first steps in grading. These BMPs must be functional before other land disturbing activities take place. b. Minimize sediment discharges from the site. The design, installation and maintenance of erosion and sediment controls must address factors such as the amount, frequency, intensity and duration of precipitation, the nature of resulting stormwater runoff, and soil characteristics, including the range of soil particle sizes expected to be present on the site. c. Direct stormwater runoff from disturbed areas through a sediment pond or other appropriate sediment removal BMP, before the runoff leaves a construction site or before discharge to an infiltration facility. Runoff from fully stabilized areas may be discharged without a sediment removal BMP, but must meet the flow control performance standard of Special Condition S9.D.3.a. d. Locate BMPs intended to trap sediment on site in a manner to avoid interference with the movement of juvenile salmonids attempting to enter off-channel areas or drainages. e. Provide and maintain natural buffers around surface waters, direct stormwater to vegetated areas to increase sediment removal and maximize stormwater infiltration, unless infeasible. f. Where feasible, design outlet structures that withdraw impounded stormwater from the surface to avoid discharging sediment that is still suspended lower in the water column. 5. Stabilize Soils a. The Permittee must stabilize exposed and unworked soils by application of effective BMPs that prevent erosion. Applicable BMPs include, but are not limited to: temporary and permanent seeding, sodding, mulching, plastic covering, erosion control fabrics and matting, soil application of polyacrylamide Construction Stormwater General Permit Page 30 (PAM), the early application of gravel base on areas to be paved, and dust control. b. The Permittee must control stormwater volume and velocity within the site to minimize soil erosion. c. The Permittee must control stormwater discharges, including both peak flow rates and total stormwater volume, to minimize erosion at outlets and to minimize downstream channel and stream bank erosion. d. Depending on the geographic location of the project, the Permittee must not allow soils to remain exposed and unworked for more than the time periods set forth below to prevent erosion: West of the Cascade Mountains Crest During the dry season (May 1 - September 30): 7 days During the wet season(October 1 - April 30): 2 days East of the Cascade Mountains Crest, except for Central Basin* During the dry season (July 1 - September 30): 10 days During the wet season(October 1 - June 30): 5 days The Central Basin*, East of the Cascade Mountains Crest During the dry season(July 1 - September 30): 30 days During the wet season(October 1 - June 30): 15 days *Note: The Central Basin is defined as the portions of Eastern Washington with mean annual precipitation of less than 12 inches. e. The Permittee must stabilize soils at the end of the shift before a holiday or weekend if needed based on the weather forecast. f. The Permittee must stabilize soil stockpiles from erosion,protected with sediment trapping measures, and where possible, be located away from storm drain inlets,waterways, and drainage channels. g. The Permittee must minimize the amount of soil exposed during construction activity. h. The Permittee must minimize the disturbance of steep slopes. i. The Permittee must minimize soil compaction and, unless infeasible, preserve topsoil. 6. Protect Slopes a. The Permittee must design and construct cut-and-fill slopes in a manner to minimize erosion. Applicable practices include, but are not limited to, reducing continuous length of slope with terracing and diversions, reducing slope steepness, and roughening slope surfaces (for example, track walking). Construction Stormwater General Permit Page 31 b. The Permittee must divert off-site stormwater(run-on) or ground water away from slopes and disturbed areas with interceptor dikes,pipes, and/or swales. Off-site stormwater should be managed separately from stormwater generated on the site. c. At the top of slopes, collect drainage in pipe slope drains or protected channels to prevent erosion. i. West of the Cascade Mountains Crest: Temporary pipe slope drains must handle the peak 10-minute flow rate from a Type IA, 10-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, 1-hour flow rate predicted by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydrologic analysis must use the existing land cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis must use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the Western Washington Hydrology Model (WWHM) to predict flows, bare soil areas should be modeled as "landscaped area." ii. East of the Cascade Mountains Crest: Temporary pipe slope drains must handle the expected peak flow rate from a 6-month, 3-hour storm for the developed condition, referred to as the short duration storm. d. Place excavated material on the uphill side of trenches, consistent with safety and space considerations. e. Place check dams at regular intervals within constructed channels that are cut down a slope. 7. Protect Drain Inlets a. Protect all storm drain inlets made operable during construction so that stormwater runoff does not enter the conveyance system without first being filtered or treated to remove sediment. b. Clean or remove and replace inlet protection devices when sediment has filled one-third of the available storage (unless a different standard is specified by the product manufacturer). 8. Stabilize Channels and Outlets a. Design, construct and stabilize all on-site conveyance channels to prevent erosion from the following expected peak flows: i. West of the Cascade Mountains Crest: Channels must handle the peak 10-minute flow rate from a Type IA, 10-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, 1-hour flow rate indicated by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydrologic analysis must use the existing land Construction Stormwater General Permit Page 32 cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis must use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the WWHM to predict flows, bare soil areas should be modeled as "landscaped area." ii. East of the Cascade Mountains Crest: Channels must handle the expected peak flow rate from a 6-month, 3-hour storm for the developed condition, referred to as the short duration storm. b. Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches at the outlets of all conveyance systems. 9. Control Pollutants Design, install, implement and maintain effective pollution prevention measures to minimize the discharge of pollutants. The Permittee must: a. Handle and dispose of all pollutants, including waste materials and demolition debris that occur on site in a manner that does not cause contamination of stormwater. b. Provide cover, containment, and protection from vandalism for all chemicals, liquid products,petroleum products, and other materials that have the potential to pose a threat to human health or the environment. On-site fueling tanks must include secondary containment. Secondary containment means placing tanks or containers within an impervious structure capable of containing 110% of the volume contained in the largest tank within the containment structure. Double- walled tanks do not require additional secondary containment. c. Conduct maintenance, fueling, and repair of heavy equipment and vehicles using spill prevention and control measures. Clean contaminated surfaces immediately following any spill incident. d. Discharge wheel wash or tire bath wastewater to a separate on-site treatment system that prevents discharge to surface water, such as closed-loop recirculation or upland land application, or to the sanitary sewer with local sewer district approval. e. Apply fertilizers and pesticides in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Follow manufacturers' label requirements for application rates and procedures. f. Use BMPs to prevent contamination of stormwater runoff by pH-modifying sources. The sources for this contamination include,but are not limited to: bulk cement, cement kiln dust, fly ash, new concrete washing and curing waters, recycled concrete stockpiles, waste streams generated from concrete grinding and sawing, exposed aggregate processes, dewatering concrete vaults, concrete Construction Stormwater General Permit Page 33 pumping and mixer washout waters. (Also refer to the definition for "concrete wastewater" in Appendix A--Definitions.) g. Adjust the pH of stormwater or authorized non-stormwater if necessary to prevent an exceedance of groundwater and/or surface water quality standards. h. Assure that washout of concrete trucks is performed off-site or in designated concrete washout areas only. Do not wash out concrete trucks or concrete handling equipment onto the ground, or into storm drains, open ditches, streets, or streams. Do not dump excess concrete on site, except in designated concrete washout areas. Concrete spillage or concrete discharge to surface waters of the State is prohibited. i. Obtain written approval from Ecology before using any chemical treatment, with the exception of CO2 or dry ice used to adjust pH. j. Uncontaminated water from water-only based shaft drilling for construction of building, road, and bridge foundations may be infiltrated provided the wastewater is managed in a way that prohibits discharge to surface waters. Prior to infiltration, water from water-only based shaft drilling that comes into contact with curing concrete must be neutralized until pH is in the range of 6.5 to 8.5 (su). 10. Control Dewatering a. Permittees must discharge foundation, vault, and trench dewatering water, which have characteristics similar to stormwater runoff at the site, into a controlled conveyance system before discharge to a sediment trap or sediment pond. b. Permittees may discharge clean, non-turbid dewatering water, such as well- point ground water, to systems tributary to, or directly into surface waters of the State, as specified in Special Condition S9.D.8,provided the dewatering flow does not cause erosion or flooding of receiving waters. Do not route clean dewatering water through stormwater sediment ponds. Note that"surface waters of the State"may exist on a construction site as well as off site; for example, a creek running through a site. c. Other dewatering treatment or disposal options may include: i. Infiltration. ii. Transport off site in a vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute state waters. iii. Ecology-approved on-site chemical treatment or other suitable treatment technologies (see S9.D.9.i. regarding chemical treatment written approval). iv. Sanitary or combined sewer discharge with local sewer district approval, if there is no other option. Construction Stormwater General Permit Page 34 V. Use of a sedimentation bag with discharge to a ditch or swale for small volumes of localized dewatering. d. Permittees must handle highly turbid or contaminated dewatering water separately from stormwater. 11. Maintain BMPs a. Permittees must maintain and repair all temporary and permanent erosion and sediment control BMPs as needed to assure continued performance of their intended function in accordance with BMP specifications. b. Permittees must remove all temporary erosion and sediment control BMPs within 30 days after achieving final site stabilization or after the temporary BMPs are no longer needed. 12. Manage the Project a. Phase development projects to the maximum degree practicable and take into account seasonal work limitations. b. Inspection and monitoring—Inspect, maintain and repair all BMPs as needed to assure continued performance of their intended function. Conduct site inspections and monitoring in accordance with Special Condition S4. c. Maintaining an updated construction SWPPP—Maintain, update, and implement the SWPPP in accordance with Special Conditions S3, S4 and S9. 13. Protect Low Impact Development(LID) BMPs The primary purpose of LID BMPs/On-site LID Stormwater Management BMPs is to reduce the disruption of the natural site hydrology. LID BMPs are permanent facilities. a. Permittees must protect all Bioretention and Rain Garden facilities from sedimentation through installation and maintenance of erosion and sediment control BMPs on portions of the site that drain into the Bioretention and/or Rain Garden facilities. Restore the facilities to their fully functioning condition if they accumulate sediment during construction. Restoring the facility must include removal of sediment and any sediment-laden Bioretention/Rain Garden soils, and replacing the removed soils with soils meeting the design specification. b. Permittees must maintain the infiltration capabilities of Bioretention and Rain Garden facilities by protecting against compaction by construction equipment and foot traffic. Protect completed lawn and landscaped areas from compaction due to construction equipment. c. Permittees must control erosion and avoid introducing sediment from surrounding land uses onto permeable pavements. Do not allow muddy Construction Stormwater General Permit Page 35 construction equipment on the base material or pavement. Do not allow sediment-laden runoff onto permeable pavements. d. Permittees must clean permeable pavements fouled with sediments or no longer passing an initial infiltration test using local stormwater manual methodology or the manufacturer's procedures. e. Permittees must keep all heavy equipment off existing soils under LID facilities that have been excavated to final grade to retain the infiltration rate of the soils. E. SWPPP—Map Contents and Requirements The Permittee's SWPPP must also include a vicinity map or general location map (for example, a USGS quadrangle map, a portion of a county or city map, or other appropriate map)with enough detail to identify the location of the construction site and receiving waters within one mile of the site. The SWPPP must also include a legible site map (or maps) showing the entire construction site. The following features must be identified,unless not applicable due to site conditions: 1. The direction of north, property lines, and existing structures and roads. 2. Cut and fill slopes indicating the top and bottom of slope catch lines. 3. Approximate slopes, contours, and direction of stormwater flow before and after major grading activities. 4. Areas of soil disturbance and areas that will not be disturbed. 5. Locations of structural and nonstructural controls (BMPs) identified in the SWPPP. 6. Locations of off-site material, stockpiles, waste storage,borrow areas, and vehicle/equipment storage areas. 7. Locations of all surface water bodies, including wetlands. 8. Locations where stormwater or non-stormwater discharges off-site and/or to a surface waterbody, including wetlands. 9. Location of water quality sampling station(s), if sampling is required by state or local permitting authority. 10. Areas where final stabilization has been accomplished and no further construction- phase permit requirements apply. 11. Location or proposed location of LID facilities. Construction Stormwater General Permit Page 36 510. NOTICE OF TERMINATION A. The site is eligible for termination of coverage when it has met any of the following conditions: 1. The site has undergone final stabilization, the Permittee has removed all temporary BMPs (except biodegradable BMPs clearly manufactured with the intention for the material to be left in place and not interfere with maintenance or land use), and all stormwater discharges associated with construction activity have been eliminated; or 2. All portions of the site that have not undergone final stabilization per Special Condition S 10.A.1 have been sold and/or transferred(per General Condition G9), and the Permittee no longer has operational control of the construction activity; or 3. For residential construction only, the Permittee has completed temporary stabilization and the homeowners have taken possession of the residences. B. When the site is eligible for termination, the Permittee must submit a complete and accurate Notice of Termination (NOT) form, signed in accordance with General Condition G2, to: Department of Ecology Water Quality Program—Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 When an electronic termination form is available, the Permittee may choose to submit a complete and accurate Notice of Termination (NOT) form through the Water Quality Permitting Portal rather than mailing a hardcopy as noted above. The termination is effective on the thirty-first calendar day following the date Ecology receives a complete NOT form,unless Ecology notifies the Permittee that the termination request is denied because the Permittee has not met the eligibility requirements in Special Condition S 1 O.A. Permittees are required to comply with all conditions and effluent limitations in the permit until the permit has been terminated. Permittees transferring the property to a new property owner or operator/Permittee are required to complete and submit the Notice of Transfer form to Ecology,but are not required to submit a Notice of Termination form for this type of transaction. Construction Stormwater General Permit Page 37 GENERAL CONDITIONS G1. DISCHARGE VIOLATIONS All discharges and activities authorized by this general permit must be consistent with the terms and conditions of this general permit. Any discharge of any pollutant more frequent than or at a level in excess of that identified and authorized by the general permit must constitute a violation of the terms and conditions of this permit. G2. SIGNATORY REQUIREMENTS A. All permit applications must bear a certification of correctness to be signed: I. In the case of corporations,by a responsible corporate officer; 2. In the case of a partnership, by a general partner of a partnership; 3. In the case of sole proprietorship,by the proprietor; or 4. In the case of a municipal, state, or other public facility, by either a principal executive officer or ranking elected official. B. All reports required by this permit and other information requested by Ecology (including NOIs,NOTs, and Transfer of Coverage forms) must be signed by a person described above or by a duly authorized representative of that person. A person is a duly authorized representative only if- 1. The authorization is made in writing by a person described above and submitted to Ecology. 2. The authorization specifies either an individual or a position having responsibility for the overall operation of the regulated facility, such as the position of plant manager, superintendent, position of equivalent responsibility, or an individual or position having overall responsibility for environmental matters. C. Changes to authorization. If an authorization under paragraph G2.B.2 above is no longer accurate because a different individual or position has responsibility for the overall operation of the facility, a new authorization satisfying the requirements of paragraph G2.13.2 above must be submitted to Ecology prior to or together with any reports, information, or applications to be signed by an authorized representative. D. Certification. Any person signing a document under this section must make the following certification: "I certify under penalty of law, that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gathered and evaluated the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering information, the information submitted is, to the best of my Construction Stormwater General Permit Page 38 knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations." G3. RIGHT OF INSPECTION AND ENTRY The Permittee must allow an authorized representative of Ecology,upon the presentation of credentials and such other documents as may be required by law: A. To enter upon the premises where a discharge is located or where any records are kept under the terms and conditions of this permit. B. To have access to and copy—at reasonable times and at reasonable cost—any records required to be kept under the terms and conditions of this permit. C. To inspect—at reasonable times—any facilities, equipment (including monitoring and control equipment), practices, methods, or operations regulated or required under this permit. D. To sample or monitor—at reasonable times—any substances or parameters at any location for purposes of assuring permit compliance or as otherwise authorized by the Clean Water Act. G4. GENERAL PERMIT MODIFICATION AND REVOCATION This permit may be modified, revoked and reissued, or terminated in accordance with the provisions of Chapter 173-226 WAC. Grounds for modification, revocation and reissuance, or termination include,but are not limited to, the following: A. When a change occurs in the technology or practices for control or abatement of pollutants applicable to the category of dischargers covered under this permit. B. When effluent limitation guidelines or standards are promulgated pursuant to the CWA or Chapter 90.48 RCW, for the category of dischargers covered under this permit. C. When a water quality management plan containing requirements applicable to the category of dischargers covered under this permit is approved, or D. When information is obtained that indicates cumulative effects on the environment from dischargers covered under this permit are unacceptable. G5. REVOCATION OF COVERAGE UNDER THE PERMIT Pursuant to Chapter 43.21B RCW and Chapter 173-226 WAC,the Director may terminate coverage for any discharger under this permit for cause. Cases where coverage may be terminated include, but are not limited to, the following: A. Violation of any term or condition of this permit. B. Obtaining coverage under this permit by misrepresentation or failure to disclose fully all relevant facts. Construction Stormwater General Permit Page 39 C. A change in any condition that requires either a temporary or permanent reduction or elimination of the permitted discharge. D. Failure or refusal of the Permittee to allow entry as required in RCW 90.48.090. E. A determination that the permitted activity endangers human health or the environment, or contributes to water quality standards violations. F. Nonpayment of permit fees or penalties assessed pursuant to RCW 90.48.465 and Chapter 173-224 WAC. G. Failure of the Permittee to satisfy the public notice requirements of WAC 173-226- 130(5), when applicable. The Director may require any discharger under this permit to apply for and obtain coverage under an individual permit or another more specific general permit. Permittees who have their coverage revoked for cause according to WAC 173-226-240 may request temporary coverage under this permit during the time an individual permit is being developed, provided the request is made within ninety(90) days from the time of revocation and is submitted along with a complete individual permit application form. G6. REPORTING A CAUSE FOR MODIFICATION The Permittee must submit a new application, or a supplement to the previous application, whenever a material change to the construction activity or in the quantity or type of discharge is anticipated which is not specifically authorized by this permit. This application must be submitted at least sixty(60) days prior to any proposed changes. Filing a request for a permit modification, revocation and reissuance, or termination, or a notification of planned changes or anticipated noncompliance does not relieve the Permittee of the duty to comply with the existing permit until it is modified or reissued. G7. COMPLIANCE WITH OTHER LAWS AND STATUTES Nothing in this permit will be construed as excusing the Permittee from compliance with any applicable federal, state, or local statutes, ordinances, or regulations. G8. DUTY TO REAPPLY The Permittee must apply for permit renewal at least 180 days prior to the specified expiration date of this permit. The Permittee must reapply using the electronic application form(NOI) available on Ecology's website. Permittees unable to submit electronically(for example, those who do not have an internet connection) must contact Ecology to request a waiver and obtain instructions on how to obtain a paper NOI. Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 Construction Stormwater General Permit Page 40 G9. TRANSFER OF GENERAL PERMIT COVERAGE Coverage under this general permit is automatically transferred to a new discharger, including operators of lots/parcels within a common plan of development or sale, if: A. A written agreement(Transfer of Coverage Form) between the current discharger (Permittee) and new discharger, signed by both parties and containing a specific date for transfer of permit responsibility, coverage, and liability(including any Administrative Orders associated with the Permit) is submitted to the Director; and B. The Director does not notify the current discharger and new discharger of the Director's intent to revoke coverage under the general permit. If this notice is not given, the transfer is effective on the date specified in the written agreement. When a current discharger(Permittee)transfers a portion of a permitted site, the current discharger must also submit an updated application form(NOI) to the Director indicating the remaining permitted acreage after the transfer. G10. REMOVED SUBSTANCES The Permittee must not re-suspend or reintroduce collected screenings, grit, solids, sludges, filter backwash, or other pollutants removed in the course of treatment or control of stormwater to the final effluent stream for discharge to state waters. G11. DUTY TO PROVIDE INFORMATION The Permittee must submit to Ecology, within a reasonable time, all information that Ecology may request to determine whether cause exists for modifying, revoking and reissuing, or terminating this permit or to determine compliance with this permit. The Permittee must also submit to Ecology,upon request, copies of records required to be kept by this permit [40 CFR 122.41(h)]. G12. OTHER REQUIREMENTS OF 40 CFR All other requirements of 40 CFR 122.41 and 122.42 are incorporated in this permit by reference. G13. ADDITIONAL MONITORING Ecology may establish specific monitoring requirements in addition to those contained in this permit by administrative order or permit modification. G14. PENALTIES FOR VIOLATING PERMIT CONDITIONS Any person who is found guilty of willfully violating the terms and conditions of this permit shall be deemed guilty of a crime, and upon conviction thereof shall be punished by a fine of up to ten thousand dollars ($10,000) and costs of prosecution, or by imprisonment at the discretion of the court. Each day upon which a willful violation occurs may be deemed a separate and additional violation. Construction Stormwater General Permit Page 41 Any person who violates the terms and conditions of a waste discharge permit shall incur, in addition to any other penalty as provided by law, a civil penalty in the amount of up to ten thousand dollars ($10,000) for every such violation. Each and every such violation shall be a separate and distinct offense, and in case of a continuing violation, every day's continuance shall be deemed to be a separate and distinct violation. G15. UPSET Definition—"Upset"means an exceptional incident in which there is unintentional and temporary noncompliance with technology-based permit effluent limitations because of factors beyond the reasonable control of the Permittee. An upset does not include noncompliance to the extent caused by operational error, improperly designed treatment facilities, inadequate treatment facilities, lack of preventive maintenance, or careless or improper operation. An upset constitutes an affirmative defense to an action brought for noncompliance with such technology-based permit effluent limitations if the requirements of the following paragraph are met. A Permittee who wishes to establish the affirmative defense of upset must demonstrate, through properly signed, contemporaneous operating logs or other relevant evidence that: 1) an upset occurred and that the Permittee can identify the cause(s) of the upset; 2)the permitted facility was being properly operated at the time of the upset; 3) the Permittee submitted notice of the upset as required in Special Condition SS.F, and; 4) the Permittee complied with any remedial measures required under this permit. In any enforcement proceeding, the Permittee seeking to establish the occurrence of an upset has the burden of proof. G16. PROPERTY RIGHTS This permit does not convey any property rights of any sort, or any exclusive privilege. G17. DUTY TO COMPLY The Permittee must comply with all conditions of this permit. Any permit noncompliance constitutes a violation of the Clean Water Act and is grounds for enforcement action; for permit termination, revocation and reissuance, or modification; or denial of a permit renewal application. G18. TOXIC POLLUTANTS The Permittee must comply with effluent standards or prohibitions established under Section 307(a) of the Clean Water Act for toxic pollutants within the time provided in the regulations that establish those standards or prohibitions, even if this permit has not yet been modified to incorporate the requirement. Construction Stormwater General Permit Page 42 G19. PENALTIES FOR TAMPERING The Clean Water Act provides that any person who falsifies, tampers with, or knowingly renders inaccurate any monitoring device or method required to be maintained under this permit shall, upon conviction, be punished by a fine of not more than $10,000 per violation, or by imprisonment for not more than two years per violation, or by both. If a conviction of a person is for a violation committed after a first conviction of such person under this condition,punishment shall be a fine of not more than$20,000 per day of violation, or imprisonment of not more than four(4) years, or both. G20. REPORTING PLANNED CHANGES The Permittee must, as soon as possible, give notice to Ecology of planned physical alterations, modifications or additions to the permitted construction activity. The Permittee should be aware that, depending on the nature and size of the changes to the original permit, a new public notice and other permit process requirements may be required. Changes in activities that require reporting to Ecology include those that will result in: A. The permitted facility being determined to be a new source pursuant to 40 CFR 122.29(b). B. A significant change in the nature or an increase in quantity of pollutants discharged, including but not limited to: for sites 5 acres or larger, a 20% or greater increase in acreage disturbed by construction activity. C. A change in or addition of surface water(s)receiving stormwater or non-stormwater from the construction activity. D. A change in the construction plans and/or activity that affects the Permittee's monitoring requirements in Special Condition S4. Following such notice,permit coverage may be modified, or revoked and reissued pursuant to 40 CFR 122.62(a) to specify and limit any pollutants not previously limited. Until such modification is effective, any new or increased discharge in excess of permit limits or not specifically authorized by this permit constitutes a violation. G21. REPORTING OTHER INFORMATION Where the Permittee becomes aware that it failed to submit any relevant facts in a permit application, or submitted incorrect information in a permit application or in any report to Ecology, it must promptly submit such facts or information. G22. REPORTING ANTICIPATED NON-COMPLIANCE The Permittee must give advance notice to Ecology by submission of a new application or supplement thereto at least forty-five (45) days prior to commencement of such discharges, of any facility expansions, production increases, or other planned changes, such as process modifications, in the permitted facility or activity which may result in noncompliance with permit limits or conditions. Any maintenance of facilities, which might necessitate Construction Stormwater General Permit Page 43 unavoidable interruption of operation and degradation of effluent quality, must be scheduled during non-critical water quality periods and carried out in a manner approved by Ecology. G23. REQUESTS TO BE EXCLUDED FROM COVERAGE UNDER THE PERMIT Any discharger authorized by this permit may request to be excluded from coverage under the general permit by applying for an individual permit. The discharger must submit to the Director an application as described in WAC 173-220-040 or WAC 173-216-070, whichever is applicable, with reasons supporting the request. These reasons will fully document how an individual permit will apply to the applicant in a way that the general permit cannot. Ecology may make specific requests for information to support the request. The Director will either issue an individual permit or deny the request with a statement explaining the reason for the denial. When an individual permit is issued to a discharger otherwise subject to the construction stormwater general permit, the applicability of the construction stormwater general permit to that Permittee is automatically terminated on the effective date of the individual permit. G24. APPEALS A. The terms and conditions of this general permit, as they apply to the appropriate class of dischargers, are subject to appeal by any person within 30 days of issuance of this general permit, in accordance with Chapter 43.21B RCW, and Chapter 173-226 WAC. B. The terms and conditions of this general permit, as they apply to an individual discharger, are appealable in accordance with Chapter 43.2113 RCW within 30 days of the effective date of coverage of that discharger. Consideration of an appeal of general permit coverage of an individual discharger is limited to the general permit's applicability or nonapplicability to that individual discharger. C. The appeal of general permit coverage of an individual discharger does not affect any other dischargers covered under this general permit. If the terms and conditions of this general permit are found to be inapplicable to any individual discharger(s), the matter shall be remanded to Ecology for consideration of issuance of an individual permit or permits. G25. SEVERABILITY The provisions of this permit are severable, and if any provision of this permit, or application of any provision of this permit to any circumstance, is held invalid, the application of such provision to other circumstances, and the remainder of this permit shall not be affected thereby. G26. BYPASS PROHIBITED A. Bypass Procedures Bypass, which is the intentional diversion of waste streams from any portion of a treatment facility, is prohibited for stormwater events below the design criteria for Construction Stormwater General Permit Page 44 stormwater management. Ecology may take enforcement action against a Permittee for bypass unless one of the following circumstances (1, 2, 3 or 4) is applicable. 1. Bypass of stormwater is consistent with the design criteria and part of an approved management practice in the applicable stormwater management manual. 2. Bypass for essential maintenance without the potential to cause violation of permit limits or conditions. Bypass is authorized if it is for essential maintenance and does not have the potential to cause violations of limitations or other conditions of this permit, or adversely impact public health. 3. Bypass of stormwater is unavoidable,unanticipated, and results in noncompliance of this permit. This bypass is permitted only if: a. Bypass is unavoidable to prevent loss of life, personal injury, or severe property damage. "Severe property damage"means substantial physical damage to property, damage to the treatment facilities which would cause them to become inoperable, or substantial and permanent loss of natural resources which can reasonably be expected to occur in the absence of a bypass. b. There are no feasible alternatives to the bypass, such as the use of auxiliary treatment facilities, retention of untreated wastes, maintenance during normal periods of equipment downtime (but not if adequate backup equipment should have been installed in the exercise of reasonable engineering judgment to prevent a bypass which occurred during normal periods of equipment downtime or preventative maintenance), or transport of untreated wastes to another treatment facility. c. Ecology is properly notified of the bypass as required in Special Condition S5.F of this permit. 4. A planned action that would cause bypass of stormwater and has the potential to result in noncompliance of this permit during a storm event. The Permittee must notify Ecology at least thirty(30) days before the planned date of bypass. The notice must contain: a. A description of the bypass and its cause. b. An analysis of all known alternatives which would eliminate,reduce, or mitigate the need for bypassing. c. A cost-effectiveness analysis of alternatives including comparative resource damage assessment. d. The minimum and maximum duration of bypass under each alternative. e. A recommendation as to the preferred alternative for conducting the bypass. Construction Stormwater General Permit Page 45 f. The projected date of bypass initiation. g. A statement of compliance with SEPA. h. A request for modification of water quality standards as provided for in WAC 173-201A-110, if an exceedance of any water quality standard is anticipated. i. Steps taken or planned to reduce, eliminate, and prevent reoccurrence of the bypass. 5. For probable construction bypasses, the need to bypass is to be identified as early in the planning process as possible. The analysis required above must be considered during preparation of the Stormwater Pollution Prevention Plan (SWPPP) and must be included to the extent practical. In cases where the probable need to bypass is determined early, continued analysis is necessary up to and including the construction period in an effort to minimize or eliminate the bypass. Ecology will consider the following before issuing an administrative order for this type bypass: a. If the bypass is necessary to perform construction or maintenance-related activities essential to meet the requirements of this permit. b. If there are feasible alternatives to bypass, such as the use of auxiliary treatment facilities, retention of untreated wastes, stopping production, maintenance during normal periods of equipment down time, or transport of untreated wastes to another treatment facility. c. If the bypass is planned and scheduled to minimize adverse effects on the public and the environment. After consideration of the above and the adverse effects of the proposed bypass and any other relevant factors, Ecology will approve, conditionally approve, or deny the request. The public must be notified and given an opportunity to comment on bypass incidents of significant duration, to the extent feasible. Approval of a request to bypass will be by administrative order issued by Ecology under RCW 90.48.120. B. Duty to Mitigate The Permittee is required to take all reasonable steps to minimize or prevent any discharge or sludge use or disposal in violation of this permit that has a reasonable likelihood of adversely affecting human health or the environment. Construction Stormwater General Permit Page 46 APPENDIX A—DEFINITIONS AKART is an acronym for"all known, available, and reasonable methods of prevention, control, and treatment."AKART represents the most current methodology that can be reasonably required for preventing, controlling, or abating the pollutants and controlling pollution associated with a discharge. Applicable TMDL means a TMDL for turbidity, fine sediment, high pH, or phosphorus,which was completed and approved by EPA before January 1, 2016, or before the date the operator's complete permit application is received by Ecology, whichever is later. Applicant means an operator seeking coverage under this permit. Benchmark means a pollutant concentration used as a permit threshold,below which a pollutant is considered unlikely to cause a water quality violation, and above which it may. When pollutant concentrations exceed benchmarks, corrective action requirements take effect. Benchmark values are not water quality standards and are not numeric effluent limitations; they are indicator values. Best Management Practices (BMPs) means schedules of activities,prohibitions of practices, maintenance procedures, and other physical, structural and/or managerial practices to prevent or reduce the pollution of waters of the State. BMPs include treatment systems, operating procedures, and practices to control: stormwater associated with construction activity, spillage or leaks, sludge or waste disposal, or drainage from raw material storage. Buffer means an area designated by a local jurisdiction that is contiguous to and intended to protect a sensitive area. Bypass means the intentional diversion of waste streams from any portion of a treatment facility. Calendar Day A period of 24 consecutive hours starting at 12:00 midnight and ending the following 12:00 midnight. Calendar Week(same as Week) means a period of seven consecutive days starting at 12:01 a.m. (0:01 hours) on Sunday. Certified Erosion and Sediment Control Lead (CESCL) means a person who has current certification through an approved erosion and sediment control training program that meets the minimum training standards established by Ecology(see BMP C160 in the SWMM). Chemical Treatment means the addition of chemicals to stormwater and/or authorized non- stormwater prior to filtration and discharge to surface waters. Clean Water Act(CWA) means the Federal Water Pollution Control Act enacted by Public Law 92-500, as amended by Public Laws 95-217, 95-576, 96-483, and 97-117; USC 1251 et seq. Combined Sewer means a sewer which has been designed to serve as a sanitary sewer and a storm sewer, and into which inflow is allowed by local ordinance. Construction Stormwater General Permit Page 47 Common Plan of Development or Sale means a site where multiple separate and distinct construction activities may be taking place at different times on different schedules and/or by different contractors, but still under a single plan. Examples include: 1)phased projects and projects with multiple filings or lots, even if the separate phases or filings/lots will be constructed under separate contract or by separate owners (e.g., a development where lots are sold to separate builders); 2) a development plan that may be phased over multiple years, but is still under a consistent plan for long-term development; 3)projects in a contiguous area that may be unrelated but still under the same contract, such as construction of a building extension and a new parking lot at the same facility; and 4) linear projects such as roads, pipelines, or utilities. If the project is part of a common plan of development or sale, the disturbed area of the entire plan must be used in determining permit requirements. Composite Sample means a mixture of grab samples collected at the same sampling point at different times, formed either by continuous sampling or by mixing discrete samples. May be "time-composite" (collected at constant time intervals) or "flow-proportional" (collected either as a constant sample volume at time intervals proportional to stream flow, or collected by increasing the volume of each aliquot as the flow increases while maintaining a constant time interval between the aliquots. Concrete Wastewater means any water used in the production,pouring and/or clean-up of concrete or concrete products, and any water used to cut, grind, wash, or otherwise modify concrete or concrete products. Examples include water used for or resulting from concrete truck/mixer/pumper/tool/chute rinsing or washing, concrete saw cutting and surfacing(sawing, coring, grinding, roughening, hydro-demolition,bridge and road surfacing). When stormwater comingles with concrete wastewater, the resulting water is considered concrete wastewater and must be managed to prevent discharge to waters of the State, including ground water. Construction Activity means land disturbing operations including clearing, grading or excavation which disturbs the surface of the land. Such activities may include road construction, construction of residential houses, office buildings, or industrial buildings, site preparation, soil compaction, movement and stockpiling of topsoils, and demolition activity. Contaminant means any hazardous substance that does not occur naturally or occurs at greater than natural background levels. See definition of"hazardous substance" and WAC 173-340-200. Contaminated Groundwater means groundwater which contains contaminants,pollutants, or hazardous substances that do not occur naturally or occur at levels greater than natural background. Contaminated Soil means soil which contains contaminants,pollutants, or hazardous substances that do not occur naturally or occur at levels greater than natural background. Demonstrably Equivalent means that the technical basis for the selection of all stormwater BMPs is documented within a SWPPP, including: 1. The method and reasons for choosing the stormwater BMPs selected. Construction Stormwater General Permit Page 48 2. The pollutant removal performance expected from the BMPs selected. 3. The technical basis supporting the performance claims for the BMPs selected, including any available data concerning field performance of the BMPs selected. 4. An assessment of how the selected BMPs will comply with state water quality standards. 5. An assessment of how the selected BMPs will satisfy both applicable federal technology- based treatment requirements and state requirements to use all known, available, and reasonable methods of prevention, control, and treatment(AKART). Department means the Washington State Department of Ecology. Detention means the temporary storage of stormwater to improve quality and/or to reduce the mass flow rate of discharge. Dewatering means the act of pumping ground water or stormwater away from an active construction site. Director means the Director of the Washington State Department of Ecology or his/her authorized representative. Discharger means an owner or operator of any facility or activity subject to regulation under Chapter 90.48 RCW or the Federal Clean Water Act. Domestic Wastewater means water carrying human wastes, including kitchen, bath, and laundry wastes from residences, buildings, industrial establishments, or other places, together with such ground water infiltration or surface waters as may be present. Ecology means the Washington State Department of Ecology. Engineered Soils means the use of soil amendments including, but not limited, to Portland cement treated base (CTB), cement kiln dust (CKD), or fly ash to achieve certain desirable soil characteristics. Equivalent BMPs means operational, source control, treatment, or innovative BMPs which result in equal or better quality of stormwater discharge to surface water or to ground water than BMPs selected from the SWMM. Erosion means the wearing away of the land surface by running water, wind, ice, or other geological agents, including such processes as gravitational creep. Erosion and Sediment Control BMPs means BMPs intended to prevent erosion and sedimentation, such as preserving natural vegetation, seeding, mulching and matting,plastic covering, filter fences, sediment traps, and ponds. Erosion and sediment control BMPs are synonymous with stabilization and structural BMPs. Federal Operator is an entity that meets the definition of"Operator" in this permit and is either any department, agency or instrumentality of the executive, legislative, and judicial branches of Construction Stormwater General Permit Page 49 the Federal government of the United States, or another entity, such as a private contractor, performing construction activity for any such department, agency, or instrumentality. Final Stabilization (same as fully stabilized or full stabilization)means the establishment of a permanent vegetative cover, or equivalent permanent stabilization measures (examples of permanent non-vegetative stabilization methods include,but are not limited to riprap, gabions or geotextiles) which prevents erosion. Ground Water means water in a saturated zone or stratum beneath the land surface or a surface waterbody. Hazardous Substance means any dangerous or extremely hazardous waste as defined in RCW 70.105.010(5)and(6),or any dangerous or extremely dangerous waste as designated by rule under chapter 70.105 RCW; any hazardous substance as defined in RCW 70.105.010(10) or any hazardous substance as defined by rule under chapter 70.105 RCW; any substance that, on the effective date of this section,is a hazardous substance under section 101(14)of the federal cleanup law,42 U.S.C., Sec. 9601(14);petroleum or petroleum products; and any substance or category of substances, including solid waste decomposition products, determined by the director by rule to present a threat to human health or the environment if released into the environment. The term hazardous substance does not include any of the following when contained in an underground storage tank from which there is not a release: crude oil or any fraction thereof or petroleum, if the tank is in compliance with all applicable federal, state, and local law. Injection Well means a well that is used for the subsurface emplacement of fluids. (See Well.) Jurisdiction means a political unit such as a city, town or county; incorporated for local self- government. National Pollutant Discharge Elimination System (NPDES)means the national program for issuing, modifying, revoking and reissuing,terminating, monitoring, and enforcing permits, and imposing and enforcing pretreatment requirements, under sections 307, 402, 318, and 405 of the Federal Clean Water Act, for the discharge of pollutants to surface waters of the State from point sources. These permits are referred to as NPDES permits and, in Washington State, are administered by the Washington State Department of Ecology. Notice of Intent (NOI) means the application for, or a request for coverage under this general permit pursuant to WAC 173-226-200. Notice of Termination (NOT)means a request for termination of coverage under this general permit as specified by Special Condition S 10 of this permit. Operator means any party associated with a construction project that meets either of the following two criteria: • The party has operational control over construction plans and specifications, including the ability to make modifications to those plans and specifications; or Construction Stormwater General Permit Page 50 • The party has day-to-day operational control of those activities at a project that are necessary to ensure compliance with a SWPPP for the site or other permit conditions (e.g., they are authorized to direct workers at a site to carry out activities required by the SWPPP or comply with other permit conditions). Permittee means individual or entity that receives notice of coverage under this general permit. pH means a liquid's measure of acidity or alkalinity. A pH of 7 is defined as neutral. Large variations above or below this value are considered harmful to most aquatic life. pH Monitoring Period means the time period in which the pH of stormwater runoff from a site must be tested a minimum of once every seven days to determine if stormwater pH is between 6.5 and 8.5. Point Source means any discernible, confined, and discrete conveyance, including but not limited to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, and container from which pollutants are or may be discharged to surface waters of the State. This term does not include return flows from irrigated agriculture. (See Fact Sheet for further explanation.) Pollutant means dredged spoil, solid waste, incinerator residue, filter backwash, sewage, garbage, domestic sewage sludge (biosolids), munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt, and industrial, municipal, and agricultural waste. This term does not include sewage from vessels within the meaning of section 312 of the CWA, nor does it include dredged or fill material discharged in accordance with a permit issued under section 404 of the CWA. Pollution means contamination or other alteration of the physical, chemical, or biological properties of waters of the State; including change in temperature, taste, color, turbidity, or odor of the waters; or such discharge of any liquid, gaseous, solid, radioactive or other substance into any waters of the State as will or is likely to create a nuisance or render such waters harmful, detrimental or injurious to the public health, safety or welfare; or to domestic, commercial, industrial, agricultural, recreational, or other legitimate beneficial uses; or to livestock, wild animals, birds, fish or other aquatic life. Process Wastewater means any water which, during manufacturing or processing, comes into direct contact with or results from the production or use of any raw material, intermediate product, finished product,byproduct, or waste product. If stormwater commingles with process wastewater, the commingled water is considered process wastewater. Receiving Water means the waterbody at the point of discharge. If the discharge is to a storm sewer system, either surface or subsurface, the receiving water is the waterbody to which the storm system discharges. Systems designed primarily for other purposes such as for ground water drainage, redirecting stream natural flows, or for conveyance of irrigation water/return flows that coincidentally convey stormwater are considered the receiving water. Construction Stormwater General Permit Page 51 Representative means a stormwater or wastewater sample which represents the flow and characteristics of the discharge. Representative samples may be a grab sample, a time- proportionate composite sample, or a flow proportionate sample. Ecology's Construction Stormwater Monitoring Manual provides guidance on representative sampling. Responsible Corporate Officer for the purpose of signatory authority means: (i) a president, secretary, treasurer, or vice-president of the corporation in charge of a principal business function, or any other person who performs similar policy- or decision-making functions for the corporation, or(ii) the manager of one or more manufacturing, production, or operating facilities, provided, the manager is authorized to make management decisions which govern the operation of the regulated facility including having the explicit or implicit duty of making major capital investment recommendations, and initiating and directing other comprehensive measures to assure long term environmental compliance with environmental laws and regulations; the manager can ensure that the necessary systems are established or actions taken to gather complete and accurate information for permit application requirements; and where authority to sign documents has been assigned or delegated to the manager in accordance with corporate procedures (40 CFR 122.22). Sanitary Sewer means a sewer which is designed to convey domestic wastewater. Sediment means the fragmented material that originates from the weathering and erosion of rocks or unconsolidated deposits, and is transported by, suspended in, or deposited by water. Sedimentation means the depositing or formation of sediment. Sensitive Area means a waterbody, wetland, stream, aquifer recharge area, or channel migration zone. SEPA(State Environmental Policy Act) means the Washington State Law, RCW 43.21C.020, intended to prevent or eliminate damage to the environment. Significant Amount means an amount of a pollutant in a discharge that is amenable to available and reasonable methods of prevention or treatment; or an amount of a pollutant that has a reasonable potential to cause a violation of surface or ground water quality or sediment management standards. Significant Concrete Work means greater than 1000 cubic yards poured concrete used over the life of a project. Significant Contributor of Pollutants means a facility determined by Ecology to be a contributor of a significant amount(s) of a pollutant(s) to waters of the State of Washington. Site means the land or water area where any "facility or activity" is physically located or conducted. Source Control BMPs means physical, structural or mechanical devices or facilities that are intended to prevent pollutants from entering stormwater. A few examples of source control Construction Stormwater General Permit Page 52 BMPs are erosion control practices, maintenance of stormwater facilities, constructing roofs over storage and working areas, and directing wash water and similar discharges to the sanitary sewer or a dead end sump. Stabilization means the application of appropriate BMPs to prevent the erosion of soils, such as, temporary and permanent seeding, vegetative covers, mulching and matting,plastic covering and sodding. See also the definition of Erosion and Sediment Control BMPs. Storm Drain means any drain which drains directly into a storm sewer system, usually found along roadways or in parking lots. Storm Sewer System means a means a conveyance, or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains designed or used for collecting or conveying stormwater. This does not include systems which are part of a combined sewer or Publicly Owned Treatment Works (POTW) as defined at 40 CFR 122.2. Stormwater means that portion of precipitation that does not naturally percolate into the ground or evaporate, but flows via overland flow, interflow, pipes, and other features of a stormwater drainage system into a defined surface waterbody, or a constructed infiltration facility. Stormwater Management Manual(SWMM) or Manual means the technical Manual published by Ecology for use by local governments that contain descriptions of and design criteria for BMPs to prevent, control, or treat pollutants in stormwater. Stormwater Pollution Prevention Plan (SWPPP) means a documented plan to implement measures to identify,prevent, and control the contamination of point source discharges of stormwater. Surface Waters of the State includes lakes, rivers, ponds, streams, inland waters, salt waters, and all other surface waters and water courses within the jurisdiction of the State of Washington. Temporary Stabilization means the exposed ground surface has been covered with appropriate materials to provide temporary stabilization of the surface from water or wind erosion. Materials include, but are not limited to, mulch, riprap, erosion control mats or blankets and temporary cover crops. Seeding alone is not considered stabilization. Temporary stabilization is not a substitute for the more permanent"final stabilization." Total Maximum Daily Load (TMDL) means a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet state water quality standards. Percentages of the total maximum daily load are allocated to the various pollutant sources. A TMDL is the sum of the allowable loads of a single pollutant from all contributing point and nonpoint sources. The TMDL calculations must include a "margin of safety" to ensure that the waterbody can be protected in case there are unforeseen events or unknown sources of the pollutant. The calculation must also account for seasonable variation in water quality. Construction Stormwater General Permit Page 53 Transfer of Coverage (TOC)means a request for transfer of coverage under this general permit as specified by General Condition G9 of this permit. Treatment BMPs means BMPs that are intended to remove pollutants from stormwater. A few examples of treatment BMPs are detention ponds, oil/water separators, biofiltration, and constructed wetlands. Transparency means a measurement of water clarity in centimeters (cm), using a 60 cm transparency tube. The transparency tube is used to estimate the relative clarity or transparency of water by noting the depth at which a black and white Secchi disc becomes visible when water is released from a value in the bottom of the tube. A transparency tube is sometimes referred to as a"turbidity tube." Turbidity means the clarity of water expressed as nephelometric turbidity units (NTUs) and measured with a calibrated turbidimeter. Uncontaminated means free from any contaminant. See definition of"contaminant" and WAC 173-340-200. Waste Load Allocation (WLA) means the portion of a receiving water's loading capacity that is allocated to one of its existing or future point sources of pollution. WLAs constitute a type of water quality based effluent limitation (40 CFR 130.2[h]). Water-only Based Shaft Drilling is a shaft drilling process that uses water only and no additives are involved in the drilling of shafts for construction of building, road, or bridge foundations. Water quality means the chemical,physical, and biological characteristics of water,usually with respect to its suitability for a particular purpose. Waters of the State includes those waters as defined as "waters of the United States" in 40 CFR Subpart 122.2 within the geographic boundaries of Washington State and "waters of the State" as defined in Chapter 90.48 RCW, which include lakes, rivers,ponds, streams, inland waters, underground waters, salt waters, and all other surface waters and water courses within the jurisdiction of the state of Washington. Well means a bored, drilled or driven shaft, or dug hole whose depth is greater than the largest surface dimension. (See Injection well.) Wheel Wash Wastewater means any water used in, or resulting from the operation of, a tire bath or wheel wash(BMP C 106: Wheel Wash), or other structure or practice that uses water to physically remove mud and debris from vehicles leaving a construction site and prevent track- out onto roads. When stormwater comingles with wheel wash wastewater, the resulting water is considered wheel wash wastewater and must be managed according to Special Condition S9.D.9. Construction Stormwater General Permit Page 54 APPENDIX B—ACRONYMS AKART All Known, Available, and Reasonable Methods of Prevention, Control, and Treatment BMP Best Management Practice CESCL Certified Erosion and Sediment Control Lead CFR Code of Federal Regulations CKD Cement Kiln Dust CM Centimeters CTB Cement-Treated Base CWA Clean Water Act DMR Discharge Monitoring Report EPA Environmental Protection Agency ERTS Environmental Report Tracking System ESC Erosion and Sediment Control FR Federal Register LID Low Impact Development NOI Notice of Intent NOT Notice of Termination NPDES National Pollutant Discharge Elimination System NTU Nephelometric Turbidity Unit RCW Revised Code of Washington SEPA State Environmental Policy Act SWMM Stormwater Management Manual SWPPP Stormwater Pollution Prevention Plan TMDL Total Maximum Daily Load UIC Underground Injection Control USC United States Code USEPA United States Environmental Protection Agency WAC Washington Administrative Code WQ Water Quality WWHM Western Washington Hydrology Model Construction Stormwater General Permit Page 55 Stormwater Pollution Prevention Plan Appendix E — Site Inspection Forms (and Site Log) The results of each inspection shall be summarized in an inspection report or checklist that is entered into or attached to the site log book. It is suggested that the inspection report or checklist be included in this appendix to keep monitoring and inspection information in one document,but this is optional. However, it is mandatory that this SWPPP and the site inspection forms be kept onsite at all times during construction, and that inspections be performed and documented as outlined below. At a minimum, each inspection report or checklist shall include: a. Inspection date/times b. Weather information: general conditions during inspection, approximate amount of precipitation since the last inspection, and approximate amount of precipitation within the last 24 hours. C. A summary or list of all BMPs that have been implemented, including observations of all erosion/sediment control structures or practices. d. The following shall be noted: i. locations of BMPs inspected, ii. locations of BMPs that need maintenance, iii. the reason maintenance is needed, iv. locations of BMPs that failed to operate as designed or intended, and v. locations where additional or different BMPs are needed, and the reason(s)why e. A description of stormwater discharged from the site. The presence of suspended sediment, turbid water, discoloration, and/or oil sheen shall be noted, as applicable. f. A description of any water quality monitoring performed during inspection, and the results of that monitoring. g. General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. h. A statement that, in the judgment of the person conducting the site inspection, the site is either in compliance or out of compliance with the terms and conditions of the SWPPP and the NPDES permit. If the site inspection indicates that the site is out of compliance, the inspection report shall include a summary of the remedial actions required to bring the site back into compliance, as well as a schedule of implementation. 28 Stormwater Pollution Prevention Plan i. Name, title, and signature of person conducting the site inspection; and the following statement: "I certify under penalty of law that this report is true, accurate, and complete, to the best of my knowledge and belief'. When the site inspection indicates that the site is not in compliance with any terms and conditions of the NPDES permit, the Permittee shall take immediate action(s)to: stop, contain, and clean up the unauthorized discharges, or otherwise stop the noncompliance; correct the problem(s); implement appropriate Best Management Practices (BMPs), and/or conduct maintenance of existing BMPs; and achieve compliance with all applicable standards and permit conditions. In addition, if the noncompliance causes a threat to human health or the environment, the Permittee shall comply with the Noncompliance Notification requirements in Special Condition S5.F of the permit. 29 Stormwater Pollution Prevention Plan Site Inspection Form General Information Project Name: Inspector Name: Title: CESCL # : Date: Time: Inspection Type: ❑ After a rain event ❑ Weekly ❑ Turbidity/transparency benchmark exceedance ❑ Other Weather Precipitation Since last inspection In last 24 hours Description of General Site Conditions: Inspection of BMPs Element 1: Mark Clearing Limits BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FY N NIP Element 2: Establish Construction Access BMP: Inspected Functioning Location Y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning problem/Corrective Action Y N FYFN NIP LLI 29 Stormwater Pollution Prevention Plan Element 3: Control Flow Rates BMP: Location Inspected Functioning problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 4: Install Sediment Controls BMP: Inspected Functioning Location y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP 30 Stormwater Pollution Prevention Plan Element S: Stabilize Soils BMP: Location Inspected Functioning problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning problem/Corrective Action Y N FY N1 NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 6: Protect Slopes BMP: Inspected Functioning Location y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP 31 Stormwater Pollution Prevention Plan Element 7: Protect Drain Inlets BMP: Location Inspected Functioning problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning problem/Corrective Action Y N FY N1 NIP Element 8: Stabilize Channels and Outlets BMP: Inspected Functioning Location y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning Problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP 32 Stormwater Pollution Prevention Plan Element 9: Control Pollutants BMP: Inspected Functioning Location y N Y N NIP Problem/Corrective Action BMP: Inspected Functioning Location y N Y N NIP Problem/Corrective Action Element 10: Control Dewatering BMP: Inspected Functioning Location y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FY N NIP 33 Stormwater Pollution Prevention Plan Stormwater Discharges From the Site Observed? Problem/Corrective Action YFN Location Turbidity Discoloration Sheen Location Turbidity Discoloration Sheen 34 Stormwater Pollution Prevention Plan Water Quality Monitoring Was any water quality monitoring conducted? ❑ Yes ❑ No If water quality monitoring was conducted, record results here: If water quality monitoring indicated turbidity 250 NTU or greater; or transparency 6 cm or less, was Ecology notified by phone within 24 hrs? ❑ Yes ❑ No If Ecology was notified, indicate the date,time, contact name and phone number below: Date: Time: Contact Name: Phone #: General Comments and Notes Include BMP repairs, maintenance, or installations made as a result of the inspection. Were Photos Taken? ❑ Yes ❑ No If photos taken, describe photos below: 35