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Home My WebLink About17601 59th Ave NE_PWD708_2026 (3) âœ” âœ” Arlington Electrical Equipment and Pole Yard 31052200400200 17601 59th Ave NE Construction of a yard to replace the existing remote yard at Tveit and 87th Ave NE Snohomish County PUD No. 1 PO Box 1107 Everett WA 98206 425-783-8624 brdavis@snopud.com Snohomish County PUD No. 1 PO Box 1107 Everett WA 98206 425-78-8624 brdavis@snopud.com Ben Davis, PE Same as Owner Everett WA 98206 425-783-8624 brdavis@snopud.com 45224 7-14-17 To be determined N/A N/A N/A N/A N/A N/A N/A N/A Benjamin Ryan Davis 08/17/2016 5,000 / 5,000 5,000 / 5,000 981,048.13 CONTRUCTION PLAN REVIEW & INSPECTION FEE WORKSHEET Community & Economic Development Department 18204 59th Avenue NE City of Arlington ï¬ ï¬ Arlington WA 98223 ï¬ (360) 403-3551 This form is to be completed and submitted with Type I , Type II Type III Construction Permit Application. 1) Based on permit type requested (Type I, Type II or Type III), complete the form as follows: ï¬ Type I permits complete all sections. ï¬ 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 ï¬ 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. PLAN REVIEW & INSPECTION FEES PLAN REVIEW & INSPECTION FEE (6% of Project Value) $ - GRADING FEE (4) (Cubic Yard ) $ - Review fees due at time of submittal Total Review Fees Due $ - 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: ï¬ Road and Alley (Public) ï¬ Stormwater Drainage and Grading (Public) ï¬ Utilities (Public) ï¬ Temporary Erosion and Sediment Control (Public and Private) ASSURANCE DEVICE Base Calculation of Performance Device $ 981,048.13 PERFORMANCE DEVICE 150% Amount Due $ 1,471,572.19 Base Calculation of Maintenance Device $ 927,403.13 MAINTENANCE DEVICE 20% Amount Due $ 185,480.63 1 CONSTRUCTION CALCULATION WORKSHEET TEMPORARY EROSION & SEDIMENT CONTROL Include Public Improvements & Private Development Description Unit Price Unit Quantity Cost Reference # Backfill & compaction-embankment $ 6.50 CY $ - Check dams $ 78.00 EACH $ - BMP C207 Catch Basin Protection $ 35.50 EACH 6 $ 213.00 Crushed surfacing 1 1/4" minus $ 18.00 TON $ - WSDOT 9-03.9(3) Ditching $ 8.00 CY $ - Excavation-bulk $ 3.00 CY 2705 $ 8,115.00 Fence, silt $ 2.00 LF 700 $ 1,400.00 BMP C233 Fence, Temporary (NGPA) $ 2.00 LF $ - Geotextile Fabric $ 2.50 SY $ - Hay Bale Silt Trap $ 0.50 EACH $ - Hydroseeding $ 4,200.00 ACRE 1 $ 4,200.00 BMP C120 Interceptor Swale / Dike $ 1.00 LF $ - Jute Mesh $ 2.00 SY $ - BMP C122 Level Spreader $ 1.75 LF $ - Mulch, by hand, straw, 3" deep $ 3.00 SY $ - BMP C121 Mulch, by machine, straw, 2" deep $ 1.00 SY 5000 $ 5,000.00 BMP C121 Piping, temporary, CPP, 6" $ 12.50 LF $ - Piping, temporary, CPP, 8" $ 19.00 LF $ - Piping, temporary, CPP, 12" $ 24.00 LF $ - Plastic covering, 6mm thick, sandbagged $ 3.00 SY 2500 $ 7,500.00 BMP C123 Rip Rap, machine placed; slopes $ 50.00 CY $ - WSDOT 9-13.1(2) Rock Construction Entrance, 50'x15'x1' $ 1,800.00 EACH $ - BMP C105 Rock Construction Entrance, 100'x15'x1' $ 3,600.00 EACH 2 $ 7,200.00 BMP C105 Sediment pond riser assembly $ 3,050.00 EACH $ - BMP C241 Sediment trap, 5' high berm $ 21.00 LF $ - BMP C240 Sed. trap, 5' high, riprapped spillway berm section $ 79.00 LF $ - BMP C240 Seeding, by hand $ 1.00 SY 5000 $ 5,000.00 BMP C120 Sodding, 1" deep, level ground $ 8.00 SY $ - BMP C120 Sodding, 1" deep, sloped ground $ 9.50 SY $ - BMP C120 TESC Supervisor $ 84.00 HR 32 $ 2,688.00 Water truck, dust control $ 130.00 HR $ - BMP C140 WRITE-IN-ITEMS High Visibility Fence $ 1.00 LF 1600 $ 1,600.00 $ - $ - $ - $ - SUBTOTAL (TESC Only): $ 42,916.00 MOBILIZATION 10%: $ 4,291.60 CONTINGENCY 15%: $ 6,437.40 TOTAL: $ 53,645.00 CONSTRUCTION CALCULATION WORKSHEET STORMWATER DRAINAGE Public Private Public Improvements Private Development Description Unit Price Unit Quantity Cost Quantity Cost Access Road, Retention / Detention $ 26.00 SY $ - $ - * (CBs include frame and lid) Beehive $ 90.00 EACH $ - $ - CB Type I $ 1,650.00 EACH 1 $ 1,650.00 $ - CB Type IL $ 1,850.00 EACH $ - $ - CB Type II, 48" Dia $ 2,550.00 EACH $ - $ - for additional depth over 4' $ 650.00 FT $ - $ - CB Type II, 54" Dia $ 2,700.00 EACH $ - $ - for additional depth over 4' $ 600.00 FT $ - $ - CB Type II, 60" Dia $ 2,900.00 EACH $ - $ - for additional depth over 4' $ 750.00 FT $ - $ - CB Type II, 72" Dia $ 4,000.00 EACH $ - $ - for additional depth over 4' $ 900.00 FT $ - $ - Through-curb Inlet Framework (Add) $ 550.00 EACH $ - $ - Cleanout, PVC, 4" $ 200.00 EACH $ - $ - Cleanout, PVC, 6" $ 250.00 EACH $ - $ - Cleanout, PVC, 8" $ 300.00 EACH $ - $ - Culvert, Box __ ft x __ ft $ - LS $ - $ - Culvert, PVC, 4" $ 12.00 LF $ - $ - Culvert, PVC, 6" $ 17.00 LF $ - $ - Culvert, PVC, 8" $ 19.00 LF $ - $ - Culvert, PVC, 12" $ 30.00 LF $ - $ - Culvert, CMP, 8" $ 23.00 LF $ - $ - Culvert, CMP, 12" $ 35.00 LF $ - $ - Culvert, CMP, 15" $ 42.00 LF $ - $ - Culvert, CMP, 18" $ 47.00 LF $ - $ - Culvert, CMP, 24" $ 69.00 LF $ - $ - Culvert, CMP, 30" $ 100.00 LF $ - $ - Culvert, CMP, 36" $ 150.00 LF $ - $ - Culvert, CMP, 48" $ 194.00 LF $ - $ - Culvert, CMP, 60" $ 310.00 LF $ - $ - Culvert, CMP, 72" $ 400.00 LF $ - $ - Culvert, Concrete, 8" $ 36.00 LF $ - $ - Culvert, Concrete, 12" $ 43.00 LF $ - $ - Culvert, Concrete, 15" $ 52.00 LF $ - $ - Culvert, Concrete, 18" $ 55.00 LF $ - $ - Culvert, Concrete, 24" $ 85.00 LF $ - $ - Culvert, Concrete, 30" $ 136.00 LF $ - $ - Culvert, Concrete, 36" $ 165.00 LF $ - $ - Culvert, Concrete, 42" $ 196.00 LF $ - $ - Culvert, Concrete, 48" $ 210.00 LF $ - $ - Culvert, CPP, 6" $ 16.00 LF $ - $ - Culvert, CPP, 8" $ 22.00 LF $ - $ - Culvert, CPP, 12" $ 28.00 LF $ - $ - Culvert, CPP, 15" $ 34.00 LF $ - $ - Culvert, CPP, 18" $ 39.00 LF $ - $ - CONSTRUCTION CALCULATION WORKSHEET Culvert, CPP, 24" $ 49.00 LF $ - $ - Culvert, CPP, 30" $ 62.00 LF $ - $ - Culvert, CPP, 36" $ 69.00 LF $ - $ - Ditching $ 12.00 CY $ - $ - Flow Dispersal Trench (1,436 base+) $ 40.00 LF $ - $ - French Drain (3' depth) $ 39.00 LF $ - $ - Geotextile, laid in trench, polypropylene $ 5.00 SY $ - $ - Infiltration pond testing $ 125.00 HR $ - $ - Mid-tank Access Riser, 48" dia, 6' deep $ 2,025.00 EACH $ - $ - Pipe, High Density Water Pipe (HDWP) $ 160.00 LF $ - $ - Pipe, C900 $ 90.00 LF $ - $ - Pond Overflow Spillway $ 18.00 SY $ - $ - Restrictor/Oil Separator, 12" $ 1,500.00 EACH $ - $ - Restrictor/Oil Separator, 15" $ 1,550.00 EACH $ - $ - Restrictor/Oil Separator, 18" $ 1,680.00 EACH $ - $ - Riprap, placed $ 52.00 CY $ - $ - Tank End Reducer (36" Dia) $ 1,280.00 EACH $ - $ - Thru-Inlet at CB $ 150.00 EACH $ - $ - Trash Rack, 12" $ 320.00 EACH $ - $ - Trash Rack, 15" $ 325.00 EACH $ - $ - Trash Rack, 18" $ 350.00 EACH $ - $ - Trash Rack, 21" $ 375.00 EACH $ - $ - WRITE-IN-ITEMS Oil/stop Valve $ 7,500.00 EACH 1 $ 7,500.00 $ - $ - $ - $ - $ - $ - $ - SUBTOTAL: $ 9,150.00 $ - MOBILIZATION 10%: $ 915.00 CONTINGENCY 15%: $ 1,372.50 TOTAL: $ 11,437.50 $ - CONSTRUCTION CALCULATION WORKSHEET GENERAL ITEMS Public Improvements Description Unit Price Unit Quantity Cost Backfill & Compaction- embankment $ 8.00 CY $ - Backfill & Compaction- trench $ 11.00 CY $ - Clear/Remove Brush, by hand (acre) $ 2,363.00 ACRE $ - Bollards - fixed $ 325.00 EACH 3 $ 975.00 Bollards - removable $ 600.00 EACH $ - Clearing/Grubbing/Tree Removal $ 6,000.00 ACRE 1 $ 6,000.00 Excavation - bulk $ 2.50 CY 2500 $ 6,250.00 Excavation - Trench $ 5.00 CY $ - Fencing, cedar, 6' high $ 25.00 LF $ - Fencing, chain link, 4' $ 19.50 LF $ - Fencing, chain link, vinyl coated, 6' high $ 18.00 LF 315 $ 5,670.00 Fencing, chain link, gate, vinyl coated, 20' $ 1,563.00 EACH 1 $ 1,563.00 Fencing, split rail, 3' high $ 14.00 LF $ - Fill & compact - common barrow $ 27.00 CY $ - Fill & compact - gravel base $ 30.00 CY $ - Fill & compact - screened topsoil $ 45.00 CY $ - Gabion, 12" deep, stone filled mesh $ 62.00 SY $ - Gabion, 18" deep, stone filled mesh $ 86.00 SY $ - Gabion, 36" deep, stone filled mesh $ 152.00 SY $ - Grading, fine, by hand $ 2.00 SY $ - Grading, fine, with grader $ 1.25 SY $ - Guard Post $ 90.00 EACH $ - Monuments $ 104.00 EACH $ - Sensitive Areas Sign $ 20.00 EACH $ - Sodding, 1" deep, sloped ground $ 10.00 SY $ - Topsoil Type A (imported) $ 30.00 CY $ - Traffic control crew ( 2 flaggers ) $ 98.00 HR $ - Trail, 4" chipped wood $ 9.00 SY $ - Trail, 4" crushed cinder $ 10.00 SY $ - Trail, 4" top course $ 9.50 SY $ - Wall, retaining, concrete $ 66.00 SF $ - Wall, rockery $ 13.00 SF $ - WRITE-IN-ITEMS 10' Tall Fencing $ 100.00 LF 1150 $ 115,000.00 10' Automatic Gate $ 20,000.00 EACH 1 $ 20,000.00 $ - $ - Subtotal $ 155,458.00 CONSTRUCTION CALCULATION WORKSHEET STREET IMPROVEMENT Public Improvements Description Unit Price Unit Quantity Cost AC Grinding, 4' wide machine < 1000sy $ 35.00 SY $ - AC Grinding, 4' wide machine 1000-2000sy $ 8.50 SY $ - AC Grinding, 4' wide machine > 2000sy $ 2.50 SY $ - AC Removal/Disposal/Repair $ 60.00 SY $ - Barricade, Type I $ 36.00 LF $ - Barricade Type II $ 25.00 LF $ - Barricade, Type III ( Permanent ) $ 55.00 LF $ - Conduit, 2" $ 5.00 LF $ - Curb & Gutter, rolled $ 20.00 LF $ - Curb & Gutter, vertical $ 15.00 LF 112 $ 1,680.00 Curb and Gutter, demolition and disposal $ 20.00 LF $ - Curb, extruded asphalt $ 5.00 LF $ - Curb, extruded concrete $ 4.50 LF $ - Guard Rail $ 30.00 LF $ - Sawcut, asphalt, 3" depth $ 3.50 LF $ - Sawcut, concrete, per 1" depth $ 3.00 LF $ - Sealant, asphalt $ 2.00 LF $ - Shoulder, gravel, 4" thick $ 11.00 SY $ - Sidewalk, 4" thick $ 40.00 SY $ - Sidewalk, 4" thick, demolition and disposal $ 36.00 SY $ - Sidewalk, 6" thick $ 45.00 SY $ - Sidewalk, 6" thick, demolition and disposal $ 45.00 SY $ - Signs $ - LS $ - Sign, Handicap $ 100.00 EACH $ - Striping, per stall $ 7.50 EACH $ - Street Light System $ - LS $ - Traffic Signal $ - LS $ - Traffic Signal Modification $ - LS $ - Striping, thermoplastic, ( for crosswalk ) $ 3.50 SF $ - Striping, 4" reflectorized line $ 0.40 LF $ - AC Patching/Trenching Restoration $ 100.00 TON $ - Controlled Density Fill (CDF) $ 90.00 CY $ - WRITE-IN-ITEMS $ - $ - $ - $ - $ - $ - Subtotal $ 1,680.00 CONSTRUCTION CALCULATION WORKSHEET STREET SURFACING/PAVEMENT Public Improvements Description Unit Price Unit Quantity Cost Asphalt Overlay, 1.5" AC $ 12.00 SY $ - Asphalt Overlay, 2" AC $ 15.00 SY $ - Asphalt Road 2", First 2500 SY $ 10.00 SY $ - Asphalt Road 2", Qty. over 2500SY $ 9.00 SY $ - Asphalt Road 3", First 2500 SY $ 15.00 SY 2500 $ 37,500.00 Asphalt Road 3", Qty. over 2500 SY $ 13.00 SY 635 $ 8,255.00 Asphalt Road 5", First 2500 SY $ 22.00 SY $ - Asphalt Road 5", Qty. Over 2500 SY $ 22.00 SY $ - Asphalt Road 6", First 2500 SY $ 25.00 SY $ - Asphalt Road 6", Qty. Over 2500 SY $ 24.00 SY $ - Asphalt Treated Base, 4" thick $ 14.00 SY 4033 $ 56,462.00 Gravel Base Course 2" $ 7.50 SY $ - Gravel Base Course 4" $ 15.00 SY $ - Gravel Base Course 6" $ 22.50 SY 3135 $ 70,537.50 Gravel Road, 4" rock, First 2500 SY $ 15.00 SY $ - Gravel Road, 4" rock, Qty. over 2500 SY $ 11.00 SY $ - Concrete Road, 5", no base, over 2500 SY $ 22.00 SY $ - Concrete Road, 6", no base, over 2500 SY $ 32.00 SY $ - Thickened Edge $ 11.00 LF $ - WRITE-IN-ITEMS AASHTO Grade No. 57 - 12" $ 50.00 SY 3135 $ 156,750.00 Bioretention soil mix - 18" $ 35.00 SY 3135 $ 109,725.00 $ - $ - Subtotal $ 439,229.50 CONSTRUCTION CALCULATION WORKSHEET WATER SYSTEM Public Improvements Description Unit Price Unit Quantity Cost Blowoff $ 1,800.00 EACH $ - Connection to Existing Water Main $ 2,000.00 EACH 2 $ 4,000.00 Ductile Iron Watermain, CL 52, 6 Inch Dia $ 65.00 LF $ - Ductile Iron Watermain, CL 52, 8 Inch Dia $ 85.00 LF 18 $ 1,530.00 Ductile Iron Watermain, CL 52, 10 Inch Dia $ 103.00 LF $ - Ductile Iron Watermain, CL 52, 12 Inch Dia. $ 125.00 LF 1015 $ 126,875.00 Gate Valve, 6 inch Dia $ 250.00 EACH $ - Gate Valve, 8 Inch Dia $ 380.00 EACH $ - Gate Valve, 10 Inch Dia $ 425.00 EACH $ - Gate Valve, 12 Inch Dia $ 500.00 EACH 2 $ 1,000.00 Fire Hydrant Assembly, with Guard Posts $ 3,000.00 EACH 1 $ 3,000.00 Fire Hydrant Assembly, without Guard Posts $ 2,500.00 EACH $ - Air-Vac, 8 Inch Dia $ 6,000.00 EACH $ - Air-Vac,10 Inch Dia $ 7,500.00 EACH $ - Air-Vac, 12 Inch Dia $ 12,000.00 EACH $ - Pressure Reducing Valve Assembly, 8 In. Dia $ 3,800.00 EACH $ - Pressure Reducing Valve Assembly, 10 In. Dia $ 4,200.00 EACH $ - Pressure Reducing Valve Assembly, 12 In. Dia $ 5,000.00 EACH $ - Valve Marker Post $ 350.00 EACH $ - WRITE-IN-ITEMS $ - $ - $ - $ - $ - Subtotal $ 136,405.00 CONSTRUCTION CALCULATION WORKSHEET SANITARY SEWER Public Improvements Description Unit Price Unit Quantity Cost Connection to Existing Sewer Main $ - EACH $ - Clean Outs $ 500.00 EACH $ - Grease Interceptor, 500 gallon $ 6,000.00 EACH $ - Grease Interceptor, 1000 gallon $ 10,000.00 EACH $ - Grease Interceptor, 1500 gallon $ 15,000.00 EACH $ - Side Sewer Pipe, PVC. 4 Inch Dia $ 8.00 LF $ - Side Sewer Pipe, PVC. 6 Inch Dia $ 12.00 LF $ - Sewer Pipe, PVC, 8 inch Dia $ 33.00 LF $ - Sewer Pipe, PVC, 12 Inch Dia $ 41.00 LF $ - Sewer Pipe, PVC, ____ Inch Dia $ - LF $ - Lift Station (Entire System) $ - LS $ - Manhole, 48 Inch Dia $ 3,000.00 EACH $ - for additional depth over 4 feet/per foot $ 532.00 FEET $ - Manhole, 54 Inch Dia $ 3,500.00 EACH $ - for additional depth over 4 feet/per foot $ 532.00 FEET $ - Manhole, 60 Inch Dia $ 3,700.00 EACH $ - for additional depth over 4 feet/per foot $ 532.00 FEET $ - Manhole, 72 Inch Dia $ 4,000.00 EACH $ - for additional depth over 4 feet/per foot $ 625.00 FEET $ - Manhole, 96 Inch Dia $ 5,000.00 EACH $ - for additional depth over 4 feet/per foot $ 625.00 FEET $ - Outside Drop $ - LS $ - Inside Drop $ - LS $ - Pipe, C-900 $ 90.00 LF $ - Pipe, High Density Water Pipe (HDWP) $ 160.00 LF $ - WRITE-IN-ITEMS $ - $ - $ - $ - $ - $ - Subtotal $ - CONSTRUCTION CALCULATION WORKSHEET LANDSCAPING & VEGETATION Include Public Improvements & Private Development Description Unit Price Unit Quantity Cost Street Trees $ 500.00 EACH $ - Root Barrier EACH $ - Median Landscaping $ - LS $ - Right-of-Way Landscaping $ - LS $ - Wetland Landscaping $ - LS $ - Private Landscaping $ - LS $ - WRITE-IN-ITEMS $ - $ - $ - $ - $ - $ - Subtotal $ - SUBTOTAL OF ALL PAGES $ 732,772.50 MOBILIZATION 10%: $ 73,277.25 CONTINGENCY 15%: $ 109,915.88 GRANDTOTAL: $ 915,965.63 Table of Contents 1.0 Project Overview ....................................................................................................................1 2.0 Existing Conditions Summary ...............................................................................................3 3.0 Off-site Analysis Report .........................................................................................................4 4.0 Minimum Requirements ........................................................................................................5 Governing Guidelines ...............................................................................................................7 Design Criteria ..........................................................................................................................7 5.0 Stormwater Control Plan .....................................................................................................14 Existing Site Hydrology .........................................................................................................14 Developed Site Hydrology .....................................................................................................14 Performance Standards and Goals ..........................................................................................15 6.0 Stormwater Pollution Prevention Plan (SWPPP) ..............................................................16 7.0 Special Reports and Studies .................................................................................................17 8.0 Other Permits ........................................................................................................................18 Table of Figures Figure 1 â€“ Vicinity Map .................................................................................................................2 Figure 2 - Flow Chart for Determining Requirements for New Development ........................6 List of Appendices Appendix A â€“ Improvement Plans Appendix B â€“ Flow Control Appendix C â€“ Runoff Treatment Appendix D â€“ Well Head Protection Zones Appendix E â€“ Soil Map Appendix F â€“ Operations and Maintenance Manual Stormwater Site Plan Page i Arlington Electrical Equipment &Pole Storage Yard July, 2016 1.0 Project Overview This Stormwater Site Plan Report provides stormwater requirements and design calculations for the proposed Snohomish County PUD No. 1 Arlington Electrical Equipment and Pole Storage Yard. The project property is located on 59th Ave NE south of the intersection with 180th Street NE, Arlington, WA 98223 within a portion of Section 22, Township 31, Range 5 East, WM. The project site is approximately 26.5 acres in area. Industrial uses border the site in all directions. 59th Ave NE borders the west side of the parcel, and railroad tracks owned by BNSF border the parcel to the east. A temporary storage yard adjacent to 59th Ave NE was constructed in 2013 creating 0.23 acres of gravel surfacing. There is no other impervious surfacing on-site. The site is predominately flat with slopes on average approximately 1-3 percent. The northeast corner of the site is approximately 10 feet higher than the western portion of the parcel. There are no known existing surface flows leaving the site. All stormwater runoff infiltrates onsite into existing outwash soils. Only a portion of the site will be developed. The 1.7 acre yard is centrally on the larger site. Access to the proposed yard will be via an access and utility easement on the AAMP (northern property owner) property. The access easement will provide a paved surface (with a minimum width of 20 feet) north to 180th Street NE and then west onto 59th Ave NE. The total disturbed area is approximately 5.0 acres. The developed storage yard is 1.7 acres in size finished with permeable gravel and asphalt. The remaining disturbed area will be used for on-site disposal of organic strippings. A water main will also be extended from the Pick and Pull site to the south connecting into the AAMP facility to the north. The proposed stormwater facilities will comply with the 2012 Department of Ecology Stormwater Management Manual for Western Washington (DOE Manual) and the City of Arlington Design and Construction Standards and Specifications. The pollution generating impervious surfaces (PGIS) will be treated by a water quality layer of material within the gravel surfacing prior to infiltrating into the existing subgrade. Refer to Section 4 of this report for additional information on the proposed drainage systems. Stormwater Site Plan Page 1 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Figure 1 â€“ Vicinity Map Project Site Stormwater Site Plan Page 2 Arlington Electrical Equipment &Pole Storage Yard July, 2016 2.0 Existing Conditions Summary The project site is approximately 26.5 acres in area. The project consists of one parcel. There is a small building, approximately 2,000 square feet centrally located on the parcel. The building, a dilapidated barn, is the only structure onsite. The rest of the parcel is vegetated predominately with grass and shrubs. There are a few trees scattered throughout the site. To the north of the site are multiple larger buildings (warehouses), and to the south of the site is a parking lot and miscellaneous buildings. The site is predominately flat with slopes on average approximately 1-3 percent. The northeast corner of the site is approximately 10 feet higher than the western portion of the parcel. There are no known existing flows leaving the site. All stormwater runoff infiltrates onsite into the existing soils. According to the Natural Resources Conservation Service (NRCS), the soils on the project site primarily consist of Lynnwood loamy sands with 0-3 % slopes with a Hydrologic Soil Group Type A. A Type A soil was used in WWHM3 for stormwater facility sizing purposes. GeoEngineers completed a geotechnical engineering report establishing a minimum of 1.2 inches/hour as the estimated long-term infiltration which was used in facility sizing. A portion of the site lies within a wellhead protection zone. A City of Arlington airport well is located approximately 2,000 feet north of the project site. The eastern half of the site which is where the proposed development is located is within the 1-year and 1-year buffer protection zones. See Appendix D for wellhead protection zone map. Stormwater Site Plan Page 3 Arlington Electrical Equipment &Pole Storage Yard July, 2016 3.0 Off-site Analysis Report This section evaluates the upstream and downstream drainage system. The intent of this section is to identify any existing or potential drainage impacts created or exacerbated by the proposed project and drainage facilities. Task 1: Study Area Definition The offsite analysis study area was conducted with the use of Snohomish County GIS aerial and topographic information and a topographic survey of the site. Task 2: Review of available information The following resources were utilized in preparation of this section: USGS Topographic Map Snohomish County PDS Permit, Planning and Zoning Interactive Map City of Arlington Wellhead protection Zone Map National Resources Conservation Service Web Soil Survey Task 3: Upstream & Downstream Study An upstream and downstream study was not completed because there is no upstream drainage basin and all stormwater infiltrates into the existing site soils. Stormwater Site Plan Page 4 Arlington Electrical Equipment &Pole Storage Yard July, 2016 4.0 Minimum Requirements Not all of the Minimum Requirements apply to every development or redevelopment project. The applicability varies depending on the type and size of the project. This section identifies thresholds that determine the applicability of the Minimum Requirements to different projects. The flow chart below identifies the applicable requirements. Stormwater Site Plan Page 5 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Figure 2 - Flow Chart for Determining Requirements for New Development Start Here Does the site have Yes See Redevelopment 35% or more of Minimum existing impervious Requirements and coverage? Flow Chart (Figure 2.3) No Does the project convert Â¾ acres of native vegetation to Does the project add No lawn or landscaped 5,000 square feet or areas, or convert 2.5 more of new acres of native impervious surfaces? vegetation to pasture? Yes No Yes Does the project have 2,000 square feet or All Minimum more of new, replaced, Requirements apply to or new plus replaced the new impervious impervious surfaces? surfaces and converted pervious surfaces. Yes No Minimum Does the project have Requirements #1 land-disturbing through #5 apply to activities of 7,000 the new and replaced Yes square feet or more? impervious surfaces and the land disturbed. No See Minimum Requirement #2, Construction Stormwater Pollution Prevention Stormwater Site Plan Page 6 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Governing Guidelines The project site is located within the City of Arlington. The Washington State Department of Ecology Stormwater Management Manual for Western Washington, 2012 (DOE Manual) will be used for stormwater design. The Western Washington Hydrology Model Version 2012 (WWHM), a continuous simulation model will be used to size all stormwater facilities. Design Criteria Per Figure 8 in the DOE Manual â€“ Flow chart for determining requirements for new development â€“ all minimum requirements apply to the area of the site being developed. The following section describes how each Minimum Requirement (MR) will be incorporated into the proposed project. MR #1 through #10 are addressed as follows: MR #1: Preparation of Stormwater Site Plans. This report and accompanying improvement plans constitute the Stormwater Site Plan. MR #2: Construction Stormwater Pollution Prevention (SWPPP). A SWPPP will be prepared as a separate document for use during construction. Even though the project likely does not require coverage by a Department of Ecolgoy Construction Stormwater General Permit due to on-site infiltration the District will obtain coverage in the unlikely event construction stormwater leaves the project site. The following section provides a detailed description of the BMPs to be implemented based on the 12 required elements of the SWPPP. For additional information refer to the project TESC plans and SWPPP. Element #1 â€“ 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. A large portion of the site will remain undisturbed throughout construction. Clearing limits will be delineated by silt fence and high visibility fence. The following relevant BMPs for this project include: BMP C101: Preserving Natural Vegetation BMP C233: Silt Fence BMP C103: High Visibility Plastic or Metal Fence Element #2 â€“ Establish Construction Access Stormwater Site Plan Page 7 Arlington Electrical Equipment &Pole Storage Yard July, 2016 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. The following relevant BMPs for this project include: BMP C105: Stabilized Construction Entrance BMP C107: Construction Road/Parking Area Stabilization Element #3 â€“ Control Flow Rates In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site will be controlled. The following relevant BMPs for this project include: Not applicable. It is anticipated that all construction stormwater will infiltrate into the existing subgrade. Element #4 â€“ Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before entering a receiving water body. The following relevant BMPs for this project include: BMP C220: Storm Drain Inlet Protection BMP C233: Silt Fence Element #5 â€“ 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 following relevant BMPs for this project include: BMP C120: Temporary and Permanent Seeding BMP C121: Mulching BMP C123: Plastic Covering 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. Element #6 â€“ Protect Slopes All cut and fill slopes shall be designed, constructed, and protected in a manner that minimizes erosion. The following relevant BMPs for this project include: Stormwater Site Plan Page 8 Arlington Electrical Equipment &Pole Storage Yard July, 2016 BMP C121: Mulching Element #7 â€“ Protect Permanent Drain Inlets All existing and proposed storm drain inlets and culverts made operable during construction that may receive stormwater on and downstream of the site shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. The following relevant BMPs for this project include: BMP C220: Storm Drain Inlet Protection Element #8 â€“ Stabilize Channels and Outlets There are no known channels and/or outlets on site to stabilize. Element #9 â€“ Control Pollutants All pollutants, including waste materials and demolition debris, that occur during construction 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. Vehicles, construction equipment, and/or petroleum product storage/dispensing: â€¢ 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. â€¢ Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. â€¢ Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. 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 C151). In order to prevent, reduce, or eliminate the discharge of pollutants from material delivery and storage to the stormwater system, Material Delivery and Storage Contamination (BMP C153) shall be implemented. Stormwater Site Plan Page 9 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Sanitary wastewater: Portable sanitation facilities will be firmly secured, regularly maintained, and emptied when necessary. Solid Waste: Solid waste will be stored in secure, clearly marked containers. Element #10 â€“ Control Dewatering Large scale dewatering is not anticipated during construction. A sedimentation bag with outfall into existing vegetation will be used for small volumes of localized de-watering. Element #11 â€“ 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 BMPâ€™s 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. Element #12 â€“ Manage the Project All BMPâ€™s shall be inspected and repaired in accordance with DOE permit requirements. The full project SWPPP will be kept on-site during construction. Element #13 â€“ Protect Low Impact Development BMPâ€™s The project does not have traditional low impact development BMPâ€™s. The project will utilize a custom biorention soil mix under a pervious gravel section for stormwater treatment. A geotechnical special inspection will be on-site during construction to verify the Contractor follows proper construction to no foul or over compact the pervious section material and/or subgrade. The District will also be providing periodic inspection to verify the TESC and SWPPP measures are properly installed and maintained throughout construction. MR #3: Source Control of Pollution. All known, available and reasonable Source Control BMPs shall be applied to this project. The District will promptly contain and clean up solid and liquid pollutant leaks and spills including oils and fuels. The District will periodically contract street sweeping to remove dust and debris that could contaminate stormwater and will not hose down Stormwater Site Plan Page 10 Arlington Electrical Equipment &Pole Storage Yard July, 2016 pollutants. The District will maintain the transformer storage area including periodic inspection of the oil stop valve and will repair the pavement and containment area if damaged. Any damaged and/or leaking equipment will promptly be removed from the site and repaired at the Districtâ€™s Operations Center. MR #4: Preservation of Natural Drainage Systems and Outfalls. The proposed stormwater site plan will maintain the existing outfall infiltrating into the existing subgrade. MR #5: On-Site Stormwater Management. The DOE Manual requires the use of on-site Stormwater Management BMPs to infiltrate, disperse, and retain stormwater runoff on-site to the maximum extent feasible without causing flooding or erosion impacts. Existing onsite soils and the proposed stormwater facility design allows for 100% infiltration of all proposed impervious and pervious surfaces from 50% of the 2 year peak flow up to the full 50 year peak flow as modeled by WWHM2012. MR #6: Runoff Treatment. The developed portion of the site will be used for industrial uses which requires enhanced water quality treatment per the DOE Manual. Treatment of stormwater runoff will be provided by a custom bioretention soil mix within the pervious (or gravel) areas. The custom bioretention soil mix complies with the Volume V, page 7-17 of the DOE Manual. A custom soil mix will be used due to a couple factors. The existing topsoil does have a cation exchange rate greater than five, however the depth of the topsoil is less than 18 inches which is insufficient for water quality treatment. The site will also be developed in the winter months which is not ideal for mixing and reuse of existing on-site materials. The paved access drives will be designed to sheet flow drainage into the pervious gravel sections for treatment prior to infiltration. The gravel areas have been designed to treat the tributary pavement areas. In order to allow for treatment within the 18â€ water quality section without backwatering during large storm events a 4â€ layer of rock was also incorporated into the gravel section to allow for ponding at the subgrade interface prior to infiltrating into the subgrade. The site design also incorporates a paved and curbed area for transformer storage. The transformers stored on-site are filled with a non-conductive mineral oil. Mineral oil transfer and/or filling will not occur on-site so the spill potential on-site is limited, however vandalism has resulted in oil spills of stored and/or operational transformer in the past. To reduce the risk of contaminating soil as a result of an accidental spill an oil stop valve and curbed area have been included in the site development plans. During Stormwater Site Plan Page 11 Arlington Electrical Equipment &Pole Storage Yard July, 2016 normal operations the transformer pavement area will drain onto the gravel section via a storm drain outlet and will be treated by the water quality section within the gravel section. The stormwater quality treatment design is discussed in more detail in Appendix C of this report. MR #7: Flow Control. All stormwater generated on the project site from the proposed impervious and pervious surfaces from 50% of the 2 year peak flow up to the full 50 year peak flow as modeled by WWHM2012 will infiltrate into the subgrade mimicking existing conditions. The long term infiltration rate of the subgrade soils has been established by grain size analysis conducted by GeoEngineers (see Geotechnical report dated May 4, 2016). GeoEngineers took several samples of the subgrade material at different locations and depths on the 26.5 acre site. The site soils are consistent briefly described as sand with a higher percentage of silt at lower depths. The proposed gravel section will require stripping a minimum of 2.5â€™ from the existing site for construction of the proposed section. The low long-term infiltration rate calculated by GeoEngineers is 1.2 inches/hour at 3 feet below existing grade. The high long-term infiltration rate calculated by GeoEngineers is 7.7 inches/hour at 6 feet below existing grade. For design of the infiltration facilities a conservative rate of 1.2 inches per hour was used to verify 100% infiltration and that ponding of water at the subgrade line did not backwater into the treatment section. The DOE Manual in Volume III, page 3-85 states that the base of all infiltration basins or trenches shall be greater or equal to 5 feet above the seasonal high water mark. This can be reduced to 3 feet with a groundwater mounding analysis. A Hydrogeologic Assessment was completed to support the site development and address this design constraint as well as discuss the sole source aquifer and it relates to the proposed site development in more detail. Two data loggers were installed and measured seasonal groundwater elevations during the rainy season for several years. In general terms the groundwater elevation from existing subgrade deepens from the south property line to the north. The maximum recorded groundwater elevation below existing grade near the middle of the site is approximately 7 feet. The maximum recorded groundwater elevation below existing grade near the south end of the site is approximately 4 feet. The proposed development borders the north property line and the bottom of the proposed facilities 2.5 feet below existing grade. Assuming the seasonal groundwater level deepens to the north the designed facilities have the required separation. This is consistent with visual observations of two stormwater ponds on the AAMP property which border the development to the north. See separate Hydrogeologic Assessment completed by GeoEngineers dated April 26, 2016 for additional information. Stormwater Site Plan Page 12 Arlington Electrical Equipment &Pole Storage Yard July, 2016 The imported materials that will be placed on the prepared subgrade in the gravel areas have a low percentage of fines and will not restrict infiltration of stormwater into the subgrade. The subgrade is the confining layer of material and the infiltration rate through this material was used in design. The stormwater infiltration design is discussed in more detail in Appendix B of this report. MR #8: Wetlands Protection There are no wetlands or wetland buffers impacting the site. MR #9: Basin/Watershed Planning. A portion of the site lies within a wellhead protection zone. A City of Arlington airport well is located approximately 2,000 feet north of the project site. The proposed gravel section with an 18 inch water quality section will provide adequate treatment of stormwater prior to infiltration reducing potential impacts to the water source. See Appendix D for wellhead protection zone map. MR #10: Operation and Maintenance. An Operation and Maintenance Manual is included in Appendix F of this report. Stormwater Site Plan Page 13 Arlington Electrical Equipment &Pole Storage Yard July, 2016 5.0 Stormwater Control Plan The following section details the selection of stormwater control BMPs and facilities that will serve the proposed project in its developed condition. The selection of stormwater control and BMP facilities follows the 2012 DOE Manual. Existing Site Hydrology The project site is 26.5-acres in area with an old dilapidated barn in the center of the property. Vegetation of the site consists of recently mowed grasses, scotch broom, blackberry and a few large deciduous and conifer trees. The site is predominately flat with slopes of approximately 2 percent. The north east corner of the site is the high side, and gently slopes to the west. The west side of the site at NE 59th Street is the low side of the site. Off-site flows are limited. Properties to the north and south are developed with existing site drainage systems. There is no observed runoff coming from the project site. Based on site observation and the geotechnical report, the majority of all stormwater runoff infiltrates into the existing soils. Refer to the Geotechnical Report prepared for this project for additional soils information. Developed Site Hydrology Developed site conditions will mimic existing site drainage conditions by infiltrating stormwater runoff into the existing subgrade. Only a portion of the 26.5 acre site will be developed for creation of the proposed Arlington Electrical Equipment and Pole Storage Yard. The developed yard is approximately 1.7 acres. During development an additional 1.5 acres will be disturbed for on-site disposal of organic strippings. The paved access drives sheet flow drainage into the pervious gravel sections for treatment prior to infiltration. The gravel areas have been designed to treat tributary pavement areas with an 18â€ water quality section. The site design also incorporates a paved, curbed area with an oil stop valve for transformer storage to reduce the risk of contaminating soil as a result of an accidental spill. During normal operations the transformer pavement area will drain onto the gravel section via a storm drain outlet and will be treated by the water quality section within the gravel section. Stormwater Site Plan Page 14 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Performance Standards and Goals The stormwater facilities have been designed using the Western Washington Hydrology Model Version 2012. The stormwater discharges match developed discharge durations to pre-developed durations for the range of pre-developed discharge rates from 50% of the 2-year peak flow up to the full 50-year peak flow. WWHM2012 is based on continuous simulation hydrology and according to the 2012 SMMWW is acceptable for sizing infiltration and water quality facilities in Western Washington. The pre-developed condition is assumed to be forested with Type A/B soils. For further detailed information concerning the design of the stormwater facilities reference Appendices B & C. Stormwater Site Plan Page 15 Arlington Electrical Equipment &Pole Storage Yard July, 2016 6.0 Stormwater Pollution Prevention Plan (SWPPP) A site specific SWPPP will be provided prior to construction. Stormwater Site Plan Page 16 Arlington Electrical Equipment &Pole Storage Yard July, 2016 7.0 Special Reports and Studies â€¢ Critical Area Reconnaissance - GeoEngineers, Inc., June 28, 2016. â€¢ Geotechnical Engineering Report - GeoEngineers, Inc., May 4, 2016 â€¢ Hydrogeologic Assessment - GeoEngineers, Inc., April 26, 2016 â€¢ Traffic Analysis â€“ Gibson Traffic Consultants, Inc., April 21, 2016 â€¢ AHERA Inspection Report â€“ Snohomish County PUD No. 1, July 14, 2014 â€¢ Cultural Resources Assessment - Cultural Resources Consultants, July 8, 2016 Stormwater Site Plan Page 17 Arlington Electrical Equipment &Pole Storage Yard July, 2016 8.0 Other Permits â€¢ City of Arlington Grading Permit â€¢ City of Arlington Zoning Permit â€¢ City of Arlington Civil Permit â€¢ Washington State Department of Ecology Construction Stormwater General Permit â€¢ SEPA Threshold Determination (Snohomish County PUD No. 1 Lead Agency) â€¢ City of Arlington Avigation Easement Stormwater Site Plan Page 18 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Appendix A â€“ Improvement Plans Stormwater Site Plan Appendix A Arlington Electrical Equipment &Pole Storage Yard July, 2016 Appendix B â€“ Flow Control Stormwater Site Plan Appendix B Arlington Electrical Equipment &Pole Storage Yard July, 2016 Sedimentation and Erosion Control In our opinion, the erosion potential of the on-site soils is low to moderate. Construction activities, including stripping and grading, will expose soils to the erosion effects of wind and water. The amount and potential impacts of erosion are partly related to the time of year that construction actually occurs. Wet weather construction will increase the amount and extent of erosion and potential sedimentation. Erosion and sedimentation control measures may be implemented by using a combination of interceptor swales, straw bale barriers, silt fences and straw mulch for temporary erosion protection of exposed soils. All disturbed areas should be finish graded and seeded as soon as practicable to reduce the risk of erosion. Erosion and sedimentation control measures should be installed and maintained in accordance with the requirements of the City of Arlington. Infiltration Facilities We understand that the District is planning to design the unpaved gravel areas for stormwater infiltration at the site. We understand that the pole storage yard gravel surfacing section will be underlain by a bioretention soil mix layer for stormwater treatment. We also understand that infiltration requirements will be designed in accordance with the Washington State Department of Ecologyâ€™s 2012 SWMMWW. Since the soils have not been glacially consolidated, a pilot infiltration test (PIT) is not required in order to estimate an initial saturated hydraulic conductivity (Ksat) per Section 3.3.4 of the SWMMWW. The initial saturated hydraulic conductivity values were estimated using the grain size analysis method per Section 3.3.6 of the SWMMWW. We completed eight grain size analyses on selected samples from our explorations. The estimated long-term (factored) saturated hydraulic conductivity values for each sample is summarized in Table 5. TABLE 5. ESTIMATED LONG-TERM SATURATED HYDRAULIC CONDUCTIVITY Long-Term Rate (factored) Ksat USCS Depth D10 D60 D90 ffines Exploration Symbol (feet) (mm) (mm) (mm) (%) (cm/s) (in/hr) B-2 SP-SM 5 0.170 5.37 16.2 5.8 3.81 x 10-3 5.4 B-3 SM 2Â½ 0.040 0.61 8.6 13.2 1.62 x 10-3 2.3 B-5 SP-SM 5 0.100 3.07 25.5 8.1 1.76 x 10-3 2.5 TP-1 SP 6 0.120 0.31 0.7 3.7 4.52 x 10-3 6.4 TP-3 SP 6 0.230 1.22 13.3 2.6 5.43 x 10-3 7.7 TP-7 SP-SM 3 0.070 0.51 3.8 11.2 2.33 x 10-3 3.3 TP-8 SM 3 0.001 0.23 0.7 27.1 8.47 x 10-4 1.2 TP-8 SP 6 0.200 0.85 8.6 2.8 5.36 x 10-3 7.6 Notes: mm = millimeter; cm/s = centimeters per second; in/hr = inchers per hour Conservative Rate used for design May 4, 2016 | Page 12 File No. 0482-051-03 NORTH CENTER INFILTRATION AREA NORTH CENTER TRIBUTARY INFILTRATION AREA PAVEMENT AREA 5,746SF = 75.8^2SF 7,489 SF = 0.17AC WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Arlington (North Center) Site Name: PUD Pole Yard Site Address: 59th Ave NE City : Arlington Report Date: 7/15/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.20 Version Date: 2016/02/25 Version : 4.2.12 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : PreDev North Center Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .3 Pervious Total 0.3 Impervious Land Use acre Impervious Total 0 Basin Total 0.3 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : North Center Pervious Bottom Length: 75.80 ft. Bottom Width: 75.80 ft. Total gravel area is Trench bottom slope 1: 0 To 1 5,746 square feet Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer: 0.33333 Pour Space of material for first layer: 0.4 Material thickness of second layer: 0 Pour Space of material for second layer: 0 Material thickness of third layer: 0 Pour Space of material for third layer: 0 Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 57.77 Total Volume Through Riser (ac-ft.): 0 No backwater into treatment layer Total Volume Through Facility (ac-ft.): 57.77 above 4 inches of rock at base of facility Percent Infiltrated: 100 Total Precip Applied to Facility: 26.715 Total Evap From Facility: 1.834 Discharge Structure Riser Height: 0.333333333 ft. Riser Diameter: 24 in. Precipitation applied to facility 5,746 sf 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 0.131 0.000 0.000 0.000 0.0148 0.131 0.000 0.000 0.159 0.0296 0.131 0.001 0.000 0.159 0.0444 0.131 0.002 0.000 0.159 0.0593 0.131 0.003 0.000 0.159 0.0741 0.131 0.003 0.000 0.159 0.0889 0.131 0.004 0.000 0.159 0.1037 0.131 0.005 0.000 0.159 0.1185 0.131 0.006 0.000 0.159 0.1333 0.131 0.007 0.000 0.159 0.1481 0.131 0.007 0.000 0.159 0.1630 0.131 0.008 0.000 0.159 0.1778 0.131 0.009 0.000 0.159 0.1926 0.131 0.010 0.000 0.159 0.2074 0.131 0.010 0.000 0.159 0.2222 0.131 0.011 0.000 0.159 0.2370 0.131 0.012 0.000 0.159 0.2519 0.131 0.013 0.000 0.159 0.2667 0.131 0.014 0.000 0.159 0.2815 0.131 0.014 0.000 0.159 0.2963 0.131 0.015 0.000 0.159 0.3111 0.131 0.016 0.000 0.159 0.3259 0.131 0.017 0.000 0.159 0.3407 0.131 0.019 0.013 0.159 0.3556 0.131 0.021 0.070 0.159 0.3704 0.131 0.023 0.151 0.159 0.3852 0.131 0.025 0.250 0.159 0.4000 0.131 0.027 0.365 0.159 0.4148 0.131 0.028 0.493 0.159 0.4296 0.131 0.030 0.633 0.159 0.4444 0.131 0.032 0.784 0.159 0.4593 0.131 0.034 0.946 0.159 0.4741 0.131 0.036 1.117 0.159 0.4889 0.131 0.038 1.297 0.159 0.5037 0.131 0.040 1.486 0.159 0.5185 0.131 0.042 1.682 0.159 0.5333 0.131 0.044 1.886 0.159 0.5481 0.131 0.046 2.097 0.159 0.5630 0.131 0.048 2.314 0.159 0.5778 0.131 0.050 2.537 0.159 0.5926 0.131 0.052 2.766 0.159 0.6074 0.131 0.054 3.000 0.159 0.6222 0.131 0.056 3.239 0.159 0.6370 0.131 0.058 3.482 0.159 0.6519 0.131 0.060 3.729 0.159 0.6667 0.131 0.062 3.979 0.159 0.6815 0.131 0.064 4.232 0.159 0.6963 0.131 0.066 4.487 0.159 0.7111 0.131 0.068 4.745 0.159 0.7259 0.131 0.070 5.004 0.159 0.7407 0.131 0.071 5.264 0.159 0.7556 0.131 0.073 5.525 0.159 0.7704 0.131 0.075 5.786 0.159 0.7852 0.131 0.077 6.047 0.159 0.8000 0.131 0.079 6.307 0.159 0.8148 0.131 0.081 6.566 0.159 0.8296 0.131 0.083 6.823 0.159 0.8444 0.131 0.085 7.078 0.159 0.8593 0.131 0.087 7.331 0.159 0.8741 0.131 0.089 7.580 0.159 0.8889 0.131 0.091 7.826 0.159 0.9037 0.131 0.093 8.068 0.159 0.9185 0.131 0.095 8.306 0.159 0.9333 0.131 0.097 8.540 0.159 0.9481 0.131 0.099 8.768 0.159 0.9630 0.131 0.101 8.991 0.159 0.9778 0.131 0.103 9.208 0.159 0.9926 0.131 0.105 9.419 0.159 1.0074 0.131 0.107 9.624 0.159 1.0222 0.131 0.109 9.823 0.159 1.0370 0.131 0.111 10.01 0.159 1.0518 0.131 0.112 10.20 0.159 1.0667 0.131 0.114 10.37 0.159 1.0815 0.131 0.116 10.54 0.159 1.0963 0.131 0.118 10.71 0.159 1.1111 0.131 0.120 10.86 0.159 1.1259 0.131 0.122 11.01 0.159 1.1407 0.131 0.124 11.15 0.159 1.1556 0.131 0.126 11.29 0.159 1.1704 0.131 0.128 11.41 0.159 1.1852 0.131 0.130 11.53 0.159 1.2000 0.131 0.132 11.65 0.159 1.2148 0.131 0.134 11.76 0.159 1.2296 0.131 0.136 11.86 0.159 1.2444 0.131 0.138 11.96 0.159 1.2593 0.131 0.140 12.05 0.159 1.2741 0.131 0.142 12.14 0.159 1.2889 0.131 0.144 12.22 0.159 1.3037 0.131 0.146 12.30 0.159 1.3185 0.131 0.148 12.38 0.159 ___________________________________________________________________ Name : Lateral I Basin 1 Bypass: No pavement tributuary to Impervious Land Use acre gravel area ROADS FLAT LAT 0.17 ___________________________________________________________________ Element Flows To: Outlet 1 Outlet 2 North Center Pervious ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.3 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.17 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000344 5 year 0.000747 10 year 0.001198 25 year 0.002092 50 year 0.003092 100 year 0.004485 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.000 1950 0.001 0.000 1951 0.000 0.000 1952 0.000 0.000 1953 0.000 0.000 1954 0.002 0.000 1955 0.001 0.000 1956 0.000 0.000 1957 0.000 0.000 1958 0.000 0.000 1959 0.001 0.000 1960 0.000 0.000 1961 0.001 0.000 1962 0.000 0.000 1963 0.000 0.000 1964 0.001 0.000 1965 0.000 0.000 1966 0.000 0.000 1967 0.000 0.000 1968 0.000 0.000 1969 0.000 0.000 1970 0.000 0.000 1971 0.001 0.000 1972 0.000 0.000 1973 0.000 0.000 1974 0.001 0.000 1975 0.000 0.000 1976 0.001 0.000 1977 0.000 0.000 1978 0.000 0.000 1979 0.000 0.000 1980 0.000 0.000 1981 0.000 0.000 1982 0.000 0.000 1983 0.000 0.000 1984 0.000 0.000 1985 0.000 0.000 1986 0.002 0.000 1987 0.001 0.000 1988 0.000 0.000 1989 0.000 0.000 1990 0.000 0.000 1991 0.000 0.000 1992 0.000 0.000 1993 0.000 0.000 1994 0.000 0.000 1995 0.000 0.000 1996 0.003 0.000 1997 0.007 0.000 1998 0.000 0.000 1999 0.000 0.000 2000 0.000 0.000 2001 0.000 0.000 2002 0.000 0.000 2003 0.000 0.000 2004 0.000 0.000 2005 0.000 0.000 2006 0.008 0.000 2007 0.000 0.000 2008 0.000 0.000 2009 0.000 0.000 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0080 0.0000 2 0.0074 0.0000 3 0.0027 0.0000 4 0.0021 0.0000 5 0.0017 0.0000 6 0.0014 0.0000 7 0.0013 0.0000 8 0.0012 0.0000 9 0.0011 0.0000 10 0.0008 0.0000 11 0.0007 0.0000 12 0.0006 0.0000 13 0.0005 0.0000 14 0.0005 0.0000 15 0.0005 0.0000 16 0.0005 0.0000 17 0.0005 0.0000 18 0.0004 0.0000 19 0.0004 0.0000 20 0.0004 0.0000 21 0.0004 0.0000 22 0.0004 0.0000 23 0.0003 0.0000 24 0.0002 0.0000 25 0.0002 0.0000 26 0.0002 0.0000 27 0.0002 0.0000 28 0.0002 0.0000 29 0.0002 0.0000 30 0.0002 0.0000 31 0.0002 0.0000 32 0.0002 0.0000 33 0.0002 0.0000 34 0.0002 0.0000 35 0.0002 0.0000 36 0.0002 0.0000 37 0.0002 0.0000 38 0.0002 0.0000 39 0.0002 0.0000 40 0.0002 0.0000 41 0.0002 0.0000 42 0.0002 0.0000 43 0.0002 0.0000 44 0.0002 0.0000 45 0.0002 0.0000 46 0.0002 0.0000 47 0.0002 0.0000 48 0.0002 0.0000 49 0.0002 0.0000 50 0.0002 0.0000 51 0.0002 0.0000 52 0.0002 0.0000 53 0.0002 0.0000 54 0.0002 0.0000 55 0.0002 0.0000 56 0.0002 0.0000 57 0.0002 0.0000 58 0.0002 0.0000 59 0.0002 0.0000 60 0.0002 0.0000 61 0.0002 0.0000 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0002 2402 0 0 Pass 0.0002 1352 0 0 Pass 0.0002 437 0 0 Pass 0.0003 112 0 0 Pass 0.0003 104 0 0 Pass 0.0003 89 0 0 Pass 0.0003 77 0 0 Pass 0.0004 66 0 0 Pass 0.0004 61 0 0 Pass 0.0004 58 0 0 Pass 0.0005 54 0 0 Pass 0.0005 50 0 0 Pass 0.0005 49 0 0 Pass 0.0006 47 0 0 Pass 0.0006 43 0 0 Pass 0.0006 40 0 0 Pass 0.0006 36 0 0 Pass 0.0007 36 0 0 Pass 0.0007 32 0 0 Pass 0.0007 31 0 0 Pass 0.0008 31 0 0 Pass 0.0008 29 0 0 Pass 0.0008 29 0 0 Pass 0.0009 27 0 0 Pass 0.0009 26 0 0 Pass 0.0009 26 0 0 Pass 0.0009 26 0 0 Pass 0.0010 25 0 0 Pass 0.0010 23 0 0 Pass 0.0010 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 21 0 0 Pass 0.0012 19 0 0 Pass 0.0012 18 0 0 Pass 0.0012 17 0 0 Pass 0.0013 16 0 0 Pass 0.0013 16 0 0 Pass 0.0013 15 0 0 Pass 0.0014 15 0 0 Pass 0.0014 14 0 0 Pass 0.0014 13 0 0 Pass 0.0014 13 0 0 Pass 0.0015 13 0 0 Pass 0.0015 13 0 0 Pass 0.0015 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0017 11 0 0 Pass 0.0017 11 0 0 Pass 0.0017 11 0 0 Pass 0.0018 11 0 0 Pass 0.0018 11 0 0 Pass 0.0018 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0021 11 0 0 Pass 0.0021 10 0 0 Pass 0.0021 9 0 0 Pass 0.0021 9 0 0 Pass 0.0022 8 0 0 Pass 0.0022 8 0 0 Pass 0.0022 8 0 0 Pass 0.0023 8 0 0 Pass 0.0023 8 0 0 Pass 0.0023 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 7 0 0 Pass 0.0026 7 0 0 Pass 0.0027 7 0 0 Pass 0.0027 7 0 0 Pass 0.0027 6 0 0 Pass 0.0028 6 0 0 Pass 0.0028 6 0 0 Pass 0.0028 6 0 0 Pass 0.0029 6 0 0 Pass 0.0029 6 0 0 Pass 0.0029 6 0 0 Pass 0.0029 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0031 5 0 0 Pass 0.0031 5 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 North Center Pervious POC N 52.61 N 99.92 Total Volume Infiltrated 52.61 0.00 0.00 99.92 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd 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 Â© by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. SOUTH CENTER INFILTRATION AREA TRIBUTARY PAVEMENT AREA 6,181 SF = 0.14AC SOUTH CENTER INFILTRATION AREA 7,868SF = 88.7^2SF WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Arlington (South Center) Site Name: PUD Pole Yard Site Address: 59th Ave NE City : Arlington Report Date: 7/15/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.20 Version Date: 2016/02/25 Version : 4.2.12 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : PreDev South Center Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .32 Pervious Total 0.32 Impervious Land Use acre Impervious Total 0 Basin Total 0.32 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : South Center Pervious Bottom Length: 88.70 ft. Bottom Width: 88.70 ft. Total gravel area is Trench bottom slope 1: 0 To 1 7,868 square feet Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer: 0.3333 Pour Space of material for first layer: 0.4 Material thickness of second layer: 0 Pour Space of material for second layer: 0 No backwater into treatment layer Material thickness of third layer: 0 Pour Space of material for third layer: 0 above 4 inches of rock at base of facility Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 60.247 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 60.247 Percent Infiltrated: 100 Total Precip Applied to Facility: 35.347 Total Evap From Facility: 2.18 Discharge Structure Riser Height: 0.3333 ft. Precipitation applied to Riser Diameter: 24 in. facility 7,868 sf 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 0.180 0.000 0.000 0.000 0.0148 0.180 0.001 0.000 0.218 0.0296 0.180 0.002 0.000 0.218 0.0444 0.180 0.003 0.000 0.218 0.0593 0.180 0.004 0.000 0.218 0.0741 0.180 0.005 0.000 0.218 0.0889 0.180 0.006 0.000 0.218 0.1037 0.180 0.007 0.000 0.218 0.1185 0.180 0.008 0.000 0.218 0.1333 0.180 0.009 0.000 0.218 0.1481 0.180 0.010 0.000 0.218 0.1630 0.180 0.011 0.000 0.218 0.1778 0.180 0.012 0.000 0.218 0.1926 0.180 0.013 0.000 0.218 0.2074 0.180 0.015 0.000 0.218 0.2222 0.180 0.016 0.000 0.218 0.2370 0.180 0.017 0.000 0.218 0.2518 0.180 0.018 0.000 0.218 0.2667 0.180 0.019 0.000 0.218 0.2815 0.180 0.020 0.000 0.218 0.2963 0.180 0.021 0.000 0.218 0.3111 0.180 0.022 0.000 0.218 0.3259 0.180 0.023 0.000 0.218 0.3407 0.180 0.026 0.013 0.218 0.3555 0.180 0.028 0.070 0.218 0.3704 0.180 0.031 0.151 0.218 0.3852 0.180 0.034 0.250 0.218 0.4000 0.180 0.036 0.365 0.218 0.4148 0.180 0.039 0.493 0.218 0.4296 0.180 0.042 0.633 0.218 0.4444 0.180 0.045 0.785 0.218 0.4592 0.180 0.047 0.946 0.218 0.4741 0.180 0.050 1.117 0.218 0.4889 0.180 0.053 1.298 0.218 0.5037 0.180 0.055 1.486 0.218 0.5185 0.180 0.058 1.683 0.218 0.5333 0.180 0.061 1.887 0.218 0.5481 0.180 0.063 2.097 0.218 0.5629 0.180 0.066 2.314 0.218 0.5778 0.180 0.069 2.538 0.218 0.5926 0.180 0.071 2.767 0.218 0.6074 0.180 0.074 3.001 0.218 0.6222 0.180 0.077 3.239 0.218 0.6370 0.180 0.079 3.482 0.218 0.6518 0.180 0.082 3.729 0.218 0.6667 0.180 0.085 3.979 0.218 0.6815 0.180 0.087 4.232 0.218 0.6963 0.180 0.090 4.488 0.218 0.7111 0.180 0.093 4.745 0.218 0.7259 0.180 0.095 5.004 0.218 0.7407 0.180 0.098 5.265 0.218 0.7555 0.180 0.101 5.526 0.218 0.7704 0.180 0.103 5.787 0.218 0.7852 0.180 0.106 6.047 0.218 0.8000 0.180 0.109 6.307 0.218 0.8148 0.180 0.111 6.566 0.218 0.8296 0.180 0.114 6.823 0.218 0.8444 0.180 0.117 7.078 0.218 0.8592 0.180 0.119 7.331 0.218 0.8741 0.180 0.122 7.580 0.218 0.8889 0.180 0.125 7.826 0.218 0.9037 0.180 0.127 8.068 0.218 0.9185 0.180 0.130 8.306 0.218 0.9333 0.180 0.133 8.540 0.218 0.9481 0.180 0.135 8.768 0.218 0.9629 0.180 0.138 8.991 0.218 0.9778 0.180 0.141 9.208 0.218 0.9926 0.180 0.144 9.419 0.218 1.0074 0.180 0.146 9.625 0.218 1.0222 0.180 0.149 9.823 0.218 1.0370 0.180 0.152 10.01 0.218 1.0518 0.180 0.154 10.20 0.218 1.0666 0.180 0.157 10.37 0.218 1.0815 0.180 0.160 10.54 0.218 1.0963 0.180 0.162 10.71 0.218 1.1111 0.180 0.165 10.86 0.218 1.1259 0.180 0.168 11.01 0.218 1.1407 0.180 0.170 11.15 0.218 1.1555 0.180 0.173 11.29 0.218 1.1703 0.180 0.176 11.41 0.218 1.1852 0.180 0.178 11.53 0.218 1.2000 0.180 0.181 11.65 0.218 1.2148 0.180 0.184 11.76 0.218 1.2296 0.180 0.186 11.86 0.218 1.2444 0.180 0.189 11.96 0.218 1.2592 0.180 0.192 12.05 0.218 1.2740 0.180 0.194 12.14 0.218 1.2889 0.180 0.197 12.22 0.218 1.3037 0.180 0.200 12.30 0.218 1.3185 0.180 0.202 12.38 0.218 ___________________________________________________________________ Name : Impervious pavement tributuary to Bypass: No gravel area Impervious Land Use acre ROADS FLAT LAT 0.14 ___________________________________________________________________ Element Flows To: Outlet 1 Outlet 2 South Center Pervious ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.32 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.14 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000367 5 year 0.000797 10 year 0.001278 25 year 0.002232 50 year 0.003298 100 year 0.004784 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.000 1950 0.001 0.000 1951 0.001 0.000 1952 0.000 0.000 1953 0.000 0.000 1954 0.002 0.000 1955 0.001 0.000 1956 0.000 0.000 1957 0.000 0.000 1958 0.000 0.000 1959 0.001 0.000 1960 0.000 0.000 1961 0.001 0.000 1962 0.000 0.000 1963 0.000 0.000 1964 0.001 0.000 1965 0.000 0.000 1966 0.000 0.000 1967 0.000 0.000 1968 0.000 0.000 1969 0.000 0.000 1970 0.000 0.000 1971 0.001 0.000 1972 0.000 0.000 1973 0.000 0.000 1974 0.001 0.000 1975 0.000 0.000 1976 0.001 0.000 1977 0.000 0.000 1978 0.000 0.000 1979 0.001 0.000 1980 0.000 0.000 1981 0.000 0.000 1982 0.000 0.000 1983 0.000 0.000 1984 0.000 0.000 1985 0.000 0.000 1986 0.002 0.000 1987 0.001 0.000 1988 0.000 0.000 1989 0.000 0.000 1990 0.000 0.000 1991 0.000 0.000 1992 0.000 0.000 1993 0.000 0.000 1994 0.000 0.000 1995 0.000 0.000 1996 0.003 0.000 1997 0.008 0.000 1998 0.000 0.000 1999 0.000 0.000 2000 0.000 0.000 2001 0.000 0.000 2002 0.000 0.000 2003 0.000 0.000 2004 0.000 0.000 2005 0.000 0.000 2006 0.009 0.000 2007 0.000 0.000 2008 0.000 0.000 2009 0.000 0.000 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0085 0.0000 2 0.0079 0.0000 3 0.0029 0.0000 4 0.0023 0.0000 5 0.0018 0.0000 6 0.0015 0.0000 7 0.0013 0.0000 8 0.0012 0.0000 9 0.0012 0.0000 10 0.0008 0.0000 11 0.0007 0.0000 12 0.0007 0.0000 13 0.0006 0.0000 14 0.0006 0.0000 15 0.0005 0.0000 16 0.0005 0.0000 17 0.0005 0.0000 18 0.0005 0.0000 19 0.0005 0.0000 20 0.0004 0.0000 21 0.0004 0.0000 22 0.0004 0.0000 23 0.0003 0.0000 24 0.0003 0.0000 25 0.0003 0.0000 26 0.0003 0.0000 27 0.0003 0.0000 28 0.0003 0.0000 29 0.0003 0.0000 30 0.0003 0.0000 31 0.0003 0.0000 32 0.0003 0.0000 33 0.0003 0.0000 34 0.0003 0.0000 35 0.0003 0.0000 36 0.0003 0.0000 37 0.0003 0.0000 38 0.0003 0.0000 39 0.0003 0.0000 40 0.0003 0.0000 41 0.0003 0.0000 42 0.0003 0.0000 43 0.0003 0.0000 44 0.0003 0.0000 45 0.0003 0.0000 46 0.0003 0.0000 47 0.0003 0.0000 48 0.0003 0.0000 49 0.0003 0.0000 50 0.0003 0.0000 51 0.0003 0.0000 52 0.0003 0.0000 53 0.0003 0.0000 54 0.0003 0.0000 55 0.0002 0.0000 56 0.0002 0.0000 57 0.0002 0.0000 58 0.0002 0.0000 59 0.0002 0.0000 60 0.0002 0.0000 61 0.0002 0.0000 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0002 2402 0 0 Pass 0.0002 1352 0 0 Pass 0.0002 437 0 0 Pass 0.0003 112 0 0 Pass 0.0003 104 0 0 Pass 0.0003 89 0 0 Pass 0.0004 77 0 0 Pass 0.0004 66 0 0 Pass 0.0004 61 0 0 Pass 0.0005 58 0 0 Pass 0.0005 54 0 0 Pass 0.0005 50 0 0 Pass 0.0006 49 0 0 Pass 0.0006 47 0 0 Pass 0.0006 43 0 0 Pass 0.0007 40 0 0 Pass 0.0007 36 0 0 Pass 0.0007 36 0 0 Pass 0.0007 32 0 0 Pass 0.0008 31 0 0 Pass 0.0008 31 0 0 Pass 0.0008 29 0 0 Pass 0.0009 29 0 0 Pass 0.0009 27 0 0 Pass 0.0009 26 0 0 Pass 0.0010 26 0 0 Pass 0.0010 26 0 0 Pass 0.0010 25 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0012 23 0 0 Pass 0.0012 23 0 0 Pass 0.0012 21 0 0 Pass 0.0013 19 0 0 Pass 0.0013 18 0 0 Pass 0.0013 17 0 0 Pass 0.0013 16 0 0 Pass 0.0014 16 0 0 Pass 0.0014 15 0 0 Pass 0.0014 15 0 0 Pass 0.0015 14 0 0 Pass 0.0015 13 0 0 Pass 0.0015 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0017 13 0 0 Pass 0.0017 13 0 0 Pass 0.0017 13 0 0 Pass 0.0018 13 0 0 Pass 0.0018 11 0 0 Pass 0.0018 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0021 11 0 0 Pass 0.0021 11 0 0 Pass 0.0021 11 0 0 Pass 0.0022 11 0 0 Pass 0.0022 11 0 0 Pass 0.0022 10 0 0 Pass 0.0023 9 0 0 Pass 0.0023 9 0 0 Pass 0.0023 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 8 0 0 Pass 0.0027 8 0 0 Pass 0.0027 8 0 0 Pass 0.0027 8 0 0 Pass 0.0028 8 0 0 Pass 0.0028 7 0 0 Pass 0.0028 7 0 0 Pass 0.0029 7 0 0 Pass 0.0029 7 0 0 Pass 0.0029 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0031 6 0 0 Pass 0.0031 6 0 0 Pass 0.0031 6 0 0 Pass 0.0032 6 0 0 Pass 0.0032 6 0 0 Pass 0.0032 6 0 0 Pass 0.0033 5 0 0 Pass 0.0033 5 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 South Center Pervious POC N 54.86 N 99.93 Total Volume Infiltrated 54.86 0.00 0.00 99.93 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd 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 Â© by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. SOUTH CENTER INFILTRATION AREA TRIBUTARY PAVEMENT AREA 11,063 SF = 0.25AC PERIMETER INFILTRATION AREA 31,223SF = 176.70^2SF WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Arlington (Perimeter) Site Name: PUD Pole Yard Site Address: 59th Ave NE City : Arlington Report Date: 7/15/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.20 Version Date: 2016/02/25 Version : 4.2.12 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : PreDev Perimeter Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .96 Pervious Total 0.96 Impervious Land Use acre Impervious Total 0 Basin Total 0.96 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : North Center Pervious Bottom Length: 176.70 ft. Bottom Width: 176.70 ft. Total gravel area is Trench bottom slope 1: 0 To 1 Trench Left side slope 0: 0 To 1 31,223 square feet Trench right side slope 2: 0 To 1 Material thickness of first layer: 0.3333 Pour Space of material for first layer: 0.4 Material thickness of second layer: 0 Pour Space of material for second layer: 0 No backwater into treatment layer Material thickness of third layer: 0 above 4 inches of rock at base of facility Pour Space of material for third layer: 0 Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 175.889 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 175.889 Percent Infiltrated: 100 Total Precip Applied to Facility: 134.404 Total Evap From Facility: 6.913 Discharge Structure Riser Height: 0.3333 ft. Precipitation applied to Riser Diameter: 24 in. facility 31,223 sf 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 0.716 0.000 0.000 0.000 0.0148 0.716 0.004 0.000 0.867 0.0296 0.716 0.008 0.000 0.867 0.0444 0.716 0.012 0.000 0.867 0.0593 0.716 0.017 0.000 0.867 0.0741 0.716 0.021 0.000 0.867 0.0889 0.716 0.025 0.000 0.867 0.1037 0.716 0.029 0.000 0.867 0.1185 0.716 0.034 0.000 0.867 0.1333 0.716 0.038 0.000 0.867 0.1481 0.716 0.042 0.000 0.867 0.1630 0.716 0.046 0.000 0.867 0.1778 0.716 0.051 0.000 0.867 0.1926 0.716 0.055 0.000 0.867 0.2074 0.716 0.059 0.000 0.867 0.2222 0.716 0.063 0.000 0.867 0.2370 0.716 0.068 0.000 0.867 0.2518 0.716 0.072 0.000 0.867 0.2667 0.716 0.076 0.000 0.867 0.2815 0.716 0.080 0.000 0.867 0.2963 0.716 0.084 0.000 0.867 0.3111 0.716 0.089 0.000 0.867 0.3259 0.716 0.093 0.000 0.867 0.3407 0.716 0.104 0.013 0.867 0.3555 0.716 0.114 0.070 0.867 0.3704 0.716 0.125 0.151 0.867 0.3852 0.716 0.135 0.250 0.867 0.4000 0.716 0.146 0.365 0.867 0.4148 0.716 0.157 0.493 0.867 0.4296 0.716 0.167 0.633 0.867 0.4444 0.716 0.178 0.785 0.867 0.4592 0.716 0.189 0.946 0.867 0.4741 0.716 0.199 1.117 0.867 0.4889 0.716 0.210 1.298 0.867 0.5037 0.716 0.220 1.486 0.867 0.5185 0.716 0.231 1.683 0.867 0.5333 0.716 0.242 1.887 0.867 0.5481 0.716 0.252 2.097 0.867 0.5629 0.716 0.263 2.314 0.867 0.5778 0.716 0.274 2.538 0.867 0.5926 0.716 0.284 2.767 0.867 0.6074 0.716 0.295 3.001 0.867 0.6222 0.716 0.305 3.239 0.867 0.6370 0.716 0.316 3.482 0.867 0.6518 0.716 0.327 3.729 0.867 0.6667 0.716 0.337 3.979 0.867 0.6815 0.716 0.348 4.232 0.867 0.6963 0.716 0.358 4.488 0.867 0.7111 0.716 0.369 4.745 0.867 0.7259 0.716 0.380 5.004 0.867 0.7407 0.716 0.390 5.265 0.867 0.7555 0.716 0.401 5.526 0.867 0.7704 0.716 0.412 5.787 0.867 0.7852 0.716 0.422 6.047 0.867 0.8000 0.716 0.433 6.307 0.867 0.8148 0.716 0.443 6.566 0.867 0.8296 0.716 0.454 6.823 0.867 0.8444 0.716 0.465 7.078 0.867 0.8592 0.716 0.475 7.331 0.867 0.8741 0.716 0.486 7.580 0.867 0.8889 0.716 0.497 7.826 0.867 0.9037 0.716 0.507 8.068 0.867 0.9185 0.716 0.518 8.306 0.867 0.9333 0.716 0.528 8.540 0.867 0.9481 0.716 0.539 8.768 0.867 0.9629 0.716 0.550 8.991 0.867 0.9778 0.716 0.560 9.208 0.867 0.9926 0.716 0.571 9.419 0.867 1.0074 0.716 0.581 9.625 0.867 1.0222 0.716 0.592 9.823 0.867 1.0370 0.716 0.603 10.01 0.867 1.0518 0.716 0.613 10.20 0.867 1.0666 0.716 0.624 10.37 0.867 1.0815 0.716 0.635 10.54 0.867 1.0963 0.716 0.645 10.71 0.867 1.1111 0.716 0.656 10.86 0.867 1.1259 0.716 0.666 11.01 0.867 1.1407 0.716 0.677 11.15 0.867 1.1555 0.716 0.688 11.29 0.867 1.1703 0.716 0.698 11.41 0.867 1.1852 0.716 0.709 11.53 0.867 1.2000 0.716 0.719 11.65 0.867 1.2148 0.716 0.730 11.76 0.867 1.2296 0.716 0.741 11.86 0.867 1.2444 0.716 0.751 11.96 0.867 1.2592 0.716 0.762 12.05 0.867 1.2740 0.716 0.773 12.14 0.867 1.2889 0.716 0.783 12.22 0.867 1.3037 0.716 0.794 12.30 0.867 1.3185 0.716 0.804 12.38 0.867 ___________________________________________________________________ Name : Lateral I Basin 1 pavement tributuary to Bypass: No gravel area Impervious Land Use acre ROADS FLAT LAT 0.25 ___________________________________________________________________ Element Flows To: Outlet 1 Outlet 2 North Center Pervious ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.96 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.25 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.001102 5 year 0.00239 10 year 0.003834 25 year 0.006695 50 year 0.009894 100 year 0.014351 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.001 0.000 1950 0.002 0.000 1951 0.002 0.000 1952 0.001 0.000 1953 0.001 0.000 1954 0.005 0.000 1955 0.004 0.000 1956 0.001 0.000 1957 0.001 0.000 1958 0.001 0.000 1959 0.002 0.000 1960 0.001 0.000 1961 0.004 0.000 1962 0.001 0.000 1963 0.001 0.000 1964 0.003 0.000 1965 0.001 0.000 1966 0.001 0.000 1967 0.001 0.000 1968 0.001 0.000 1969 0.001 0.000 1970 0.001 0.000 1971 0.004 0.000 1972 0.001 0.000 1973 0.001 0.000 1974 0.002 0.000 1975 0.001 0.000 1976 0.002 0.000 1977 0.001 0.000 1978 0.001 0.000 1979 0.002 0.000 1980 0.001 0.000 1981 0.001 0.000 1982 0.001 0.000 1983 0.001 0.000 1984 0.001 0.000 1985 0.001 0.000 1986 0.007 0.000 1987 0.004 0.000 1988 0.001 0.000 1989 0.001 0.000 1990 0.001 0.000 1991 0.001 0.000 1992 0.001 0.000 1993 0.001 0.000 1994 0.001 0.000 1995 0.001 0.000 1996 0.009 0.000 1997 0.024 0.000 1998 0.001 0.000 1999 0.001 0.000 2000 0.001 0.000 2001 0.001 0.000 2002 0.001 0.000 2003 0.001 0.000 2004 0.001 0.000 2005 0.001 0.000 2006 0.026 0.000 2007 0.001 0.000 2008 0.001 0.000 2009 0.001 0.000 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0256 0.0000 2 0.0238 0.0000 3 0.0087 0.0000 4 0.0068 0.0000 5 0.0053 0.0000 6 0.0044 0.0000 7 0.0040 0.0000 8 0.0037 0.0000 9 0.0036 0.0000 10 0.0025 0.0000 11 0.0022 0.0000 12 0.0020 0.0000 13 0.0017 0.0000 14 0.0017 0.0000 15 0.0016 0.0000 16 0.0015 0.0000 17 0.0015 0.0000 18 0.0014 0.0000 19 0.0014 0.0000 20 0.0013 0.0000 21 0.0012 0.0000 22 0.0011 0.0000 23 0.0009 0.0000 24 0.0008 0.0000 25 0.0008 0.0000 26 0.0008 0.0000 27 0.0008 0.0000 28 0.0008 0.0000 29 0.0008 0.0000 30 0.0008 0.0000 31 0.0008 0.0000 32 0.0008 0.0000 33 0.0008 0.0000 34 0.0008 0.0000 35 0.0008 0.0000 36 0.0008 0.0000 37 0.0008 0.0000 38 0.0008 0.0000 39 0.0008 0.0000 40 0.0008 0.0000 41 0.0008 0.0000 42 0.0008 0.0000 43 0.0008 0.0000 44 0.0008 0.0000 45 0.0008 0.0000 46 0.0008 0.0000 47 0.0008 0.0000 48 0.0008 0.0000 49 0.0008 0.0000 50 0.0008 0.0000 51 0.0008 0.0000 52 0.0008 0.0000 53 0.0008 0.0000 54 0.0008 0.0000 55 0.0007 0.0000 56 0.0007 0.0000 57 0.0007 0.0000 58 0.0007 0.0000 59 0.0007 0.0000 60 0.0007 0.0000 61 0.0005 0.0000 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0006 2355 0 0 Pass 0.0006 1329 0 0 Pass 0.0007 438 0 0 Pass 0.0008 112 0 0 Pass 0.0009 103 0 0 Pass 0.0010 89 0 0 Pass 0.0011 77 0 0 Pass 0.0012 66 0 0 Pass 0.0013 61 0 0 Pass 0.0014 58 0 0 Pass 0.0015 54 0 0 Pass 0.0016 50 0 0 Pass 0.0017 49 0 0 Pass 0.0018 47 0 0 Pass 0.0019 43 0 0 Pass 0.0020 40 0 0 Pass 0.0021 36 0 0 Pass 0.0022 36 0 0 Pass 0.0022 32 0 0 Pass 0.0023 31 0 0 Pass 0.0024 31 0 0 Pass 0.0025 29 0 0 Pass 0.0026 29 0 0 Pass 0.0027 27 0 0 Pass 0.0028 26 0 0 Pass 0.0029 26 0 0 Pass 0.0030 26 0 0 Pass 0.0031 25 0 0 Pass 0.0032 23 0 0 Pass 0.0033 23 0 0 Pass 0.0034 23 0 0 Pass 0.0035 23 0 0 Pass 0.0036 23 0 0 Pass 0.0037 21 0 0 Pass 0.0038 19 0 0 Pass 0.0039 18 0 0 Pass 0.0039 17 0 0 Pass 0.0040 16 0 0 Pass 0.0041 16 0 0 Pass 0.0042 15 0 0 Pass 0.0043 15 0 0 Pass 0.0044 14 0 0 Pass 0.0045 13 0 0 Pass 0.0046 13 0 0 Pass 0.0047 13 0 0 Pass 0.0048 13 0 0 Pass 0.0049 13 0 0 Pass 0.0050 13 0 0 Pass 0.0051 13 0 0 Pass 0.0052 13 0 0 Pass 0.0053 13 0 0 Pass 0.0054 11 0 0 Pass 0.0055 11 0 0 Pass 0.0056 11 0 0 Pass 0.0056 11 0 0 Pass 0.0057 11 0 0 Pass 0.0058 11 0 0 Pass 0.0059 11 0 0 Pass 0.0060 11 0 0 Pass 0.0061 11 0 0 Pass 0.0062 11 0 0 Pass 0.0063 11 0 0 Pass 0.0064 11 0 0 Pass 0.0065 11 0 0 Pass 0.0066 10 0 0 Pass 0.0067 10 0 0 Pass 0.0068 9 0 0 Pass 0.0069 9 0 0 Pass 0.0070 8 0 0 Pass 0.0071 8 0 0 Pass 0.0072 8 0 0 Pass 0.0073 8 0 0 Pass 0.0073 8 0 0 Pass 0.0074 8 0 0 Pass 0.0075 8 0 0 Pass 0.0076 8 0 0 Pass 0.0077 8 0 0 Pass 0.0078 8 0 0 Pass 0.0079 8 0 0 Pass 0.0080 8 0 0 Pass 0.0081 8 0 0 Pass 0.0082 8 0 0 Pass 0.0083 8 0 0 Pass 0.0084 7 0 0 Pass 0.0085 7 0 0 Pass 0.0086 7 0 0 Pass 0.0087 7 0 0 Pass 0.0088 6 0 0 Pass 0.0089 6 0 0 Pass 0.0090 6 0 0 Pass 0.0090 6 0 0 Pass 0.0091 6 0 0 Pass 0.0092 6 0 0 Pass 0.0093 6 0 0 Pass 0.0094 6 0 0 Pass 0.0095 6 0 0 Pass 0.0096 6 0 0 Pass 0.0097 6 0 0 Pass 0.0098 5 0 0 Pass 0.0099 5 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 North Center Pervious POC N 160.09 N 99.98 Total Volume Infiltrated 160.09 0.00 0.00 99.98 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd 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 Â© by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. Appendix C â€“ Runoff Treatment Stormwater Site Plan Appendix C Arlington Electrical Equipment &Pole Storage Yard July, 2016 8410 154th Avenue NE Redmond, Washington 98052 425.861.6000 August 16, 2016 Snohomish County PUD No. 1 Facilities Department 2323 California Street P.O. Box 1107 Everett, Washington 98206 Attention: Ben Davis, PE Subject: Custom Bioretention Soil Mix Proposed Pole Storage Yard Arlington Site Development Arlington, Washington File No. 0482-051-03 INTRODUCTION This letter contains the laboratory testing results and recommendations for a custom bioretention soil mix for use in the design and construction of the proposed Pole Storage Yard at the Districtâ€™s Arlington Site located between 172nd Street NE and 180th Street NE off of 59th Avenue NE in Arlington, Washington. GeoEngineers previously prepared a geotechnical report for the project titled, â€œGeotechnical Engineering Services, Proposed Pole Storage Yard, Arlington Site Development, Arlington, Washington,â€ dated May 4, 2016. Project Description We understand that a portion of the Arlington property is being developed for a Pole Storage Yard to store treated poles and transformers. Development of the pole storage yard will include constructing gravel laydown areas, asphalt paved access roads and transformer storage areas, and installation of a water line. We understand that the native soils do not meet the minimum requirements for treatment of stormwater infiltration at the site. In order to meet storm water guidelines, the District is looking at using an imported amended soil mix that will be placed below the pole storage yard surfacing gravel to improve treatment of stormwater infiltration. The amended material will need to support occasional truck traffic loads, therefore the Default Bioretention Soil Media (BSM) standard 60/40 compost soil mix (by volume) from the 2014 Stormwater Management Manual for Western Washington (SWMMWW) will not be sufficient from a structural support standpoint. Snohomish County PUD No. 1 | August 16, 2016 Page 2 Purpose and Scope The purpose of our engineering services is to develop a custom bioretention soil using a compost and gravel borrow mixture which will: (1) meet the 2014 SWMMWW requirements for a custom bioretention soil mix and (2) provide support for occasional truck traffic. CUSTOM BIORETENTION SOIL MIX REQUIREMENTS We understand that the 2014 SWMMWW allows for development of a custom bioretention soil mix. The SWMMWW lists the following criteria for a custom soil mix: â– Cation-exchange capacity (CEC) â‰¥ 5 milliequivalents/100 grams of dry soil; USEPA 9081. â– pH between 5.5 and 7.0. â– 5 to 8 percent organic matter content (by weight) before and after the saturated hydraulic conductivity test (ASTM D 2974). â– 2 to 5 percent fines passing the U.S. Standard No. 200 sieve â– Measured (initial) saturated hydraulic conductivity of less than 12 inches per hour; ASTM D 2434 (constant head) at 85 percent and 90 percent compaction (ASTM D 1557) as modified by Appendix V-B of the SWMMWW. â– Design (long-term) saturated hydraulic conductivity of more than 1 inch per hour. â– Compost to meet requirements of Volume V of the SWMMWW. SAMPLES FOR TESTING Gravel borrow and compost samples were collected from Lenz Enterprises, Inc. on June 15, 2016. Grain size analysis test results for the gravel borrow are presented in Appendix A. The borrow sample material meets the Washington State Department of Transportation (WSDOT) requirements for gravel borrow and is classified as a poorly graded sand with gravel with 4 percent passing the 200 sieve. The technical data sheet for the compost material that we received is presented in Appendix A (Figure A-1). File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 3 LABORATORY TESTING CEC Testing Cation Exchange Capacity (CEC) testing was performed following USEPA 9081 on a 5, 10, 15 and 20 percent compost to gravel borrow mix. The CEC test results are presented in Appendix A and are shown on the plot below. 10 9 8 7 6 5 4 3 CEC (meq/100grm) 2 1 0 0 5 10 15 20 25 Percent Compost by Weight pH Testing pH testing was performed on a 5, 10, 15 and 20 percent compost to gravel borrow mix. The pH test results are shown on the plot below. pH tests were also performed on the gravel borrow (pH = 6.1) and the compost (pH = 8.2) for baseline purposes. 10 9 8 7 6 pH5 4 3 2 1 0 0 5 10 15 20 25 Percent Compost by Weight File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 4 Organic Content Testing Organic content testing was performed following ASTM D 2974 on a 5, 10, 15 and 20 percent compost to gravel borrow mix prior to conducting the saturated hydraulic conductivity tests. One organic content test was performed on the 15 percent compost to gravel borrow mix following the saturated hydraulic conductivity test. The organic content test results are shown on the plot below. 10 9 8 7 6 5 4 3 2 Organic Content (percent)1 0 0 5 10 15 20 25 Percent Compost by Weight Before Hydraulic Conductivity Test After Hydraulic Conductivity Test Grain Size Analysis Grain size analysis testing was performed following ASTM D 6913 on the gravel borrow sample, the 10, 15 and 20 percent compost to gravel borrow mix. The grain size analysis test results are presented in Appendix A (Figure A-2). Proctor Testing Laboratory compaction testing was performed following ASTM D 1157 on the 10, 15 and 20 percent compost to gravel borrow mix designs. The laboratory compaction test results are presented in Appendix A (Figures A-3 through A-5) and the measured maximum dry density (MDD) test results are shown on the plot below. 128 126 124 122 120 118 116 114 112 110 108 Maximum Dry Density (pcf) 106 0 5 10 15 20 25 Percent Compost by Weight Uncorrected With Rock Correction File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 5 Saturated Hydraulic Conductivity Testing Saturated hydraulic conductivity testing was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 SWMMWW at 85 percent compaction (ASTM D 1557). The tests were completed on samples compacted at 85 and 90 percent of the MDD, respectively. The measured (initial) saturated hydraulic conductivity test results are presented in Appendix A (Figures A-6 through A-8) and are summarized on the plot below. 25 85% Compaction 20 90% Compaction 15 10 5 Measured (initial) saturated hydraulic conductivity (in/hour) 0 0 5 10 15 20 25 Percent Compost by Weight The 2014 SWMMWW recommends a factor of safety of 4.0 for the design hydraulic conductivity value. The design (long-term) saturated hydraulic conductivity values with an applied safety factor of 4.0 is shown in the plot below for the samples compacted at 85 and 90 percent of the MDD. 7 6 85% Compaction 90% Compaction 5 4 -term) saturated 3 2 1 Design (long hydraulic conductivity (in/hour) 0 0 5 10 15 20 25 Percent Compost by Weight CONCLUSIONS AND RECOMMENDATIONS Based on the results of the laboratory testing, the 15 percent compost to gravel borrow mix meets the requirements of the 2014 SWMMWW Design Criteria for Custom Bioretention Soil Mixes, with the exception of the pH values, which were slightly higher than the 7.0 maximum requirement. The pH of the tested File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 6 compost sample was 8.2. For the project specifications, we recommend compost with a pH between 5 and 7 be used for the bioretention soil mix in order to meet the SWMMWW design criteria. We recommend that the project specifications require gravel borrow be amended with 15 percent compost by weight for the custom bioretention soil mix below the gravel surfaced Pole Storage Yard. The gravel borrow should meet the requirements of section 9-03.14(1) of the 2016 WSDOT Standard Specifications. The compost should meet the requirements of the 2014 SWMMWW for bioretention. The materials should be adequately mixed to provide a uniform blended soil. The project specifications should require the contractor submit samples of their proposed custom bioretention soil mix for testing and verification purposes. GeoEngineers should test the submitted samples to confirm that the requirements of 2014 SWMMWW are satisfied (BMP T7.30, Design Criteria for Custom Bioretention Soil Mixes). A minimum 18-inch layer of the custom bioretention soil mix should be placed and compacted in areas designated for stormwater treatment. We recommend the bioretention soil mix be compacted in maximum 12 inch loose lifts to at least 85 percent of the MDD (corrected for gravel content) as determined by ASTM D 1557. This compaction effort is less than the standard of practice for support of traffic, therefore, periodic maintenance may be needed to repair rutting within the gravel surfacing if occasional vehicles are routed over these unpaved areas. The bioretention soil mix should not be placed below the asphalt or concrete paved areas of the site. In our opinion, a geotextile separation fabric is not needed above or below the bioretention gravel borrow mix, provided the bioretention soil is prepared as described above. The subgrade conditions and gravel surfacing recommendations provided in our May 4, 2016 geotechnical report should be followed. Although our proposed bioretention soil mix satisfies the 2014 SWMMWW design criteria for stormwater treatment, the structural capacity of the mix is limited because of the organic content and compaction criteria, and is not intended for support of significant equipment traffic. LIMITATIONS We have prepared this report for Snohomish County PUD No. 1. Copies of this report may be distributed to authorized agents and regulatory agencies as may be required for the project. Our evaluation pertains only to the physical properties of soil mechanics and hydrogeology as it pertains to the requirements of the 2014 SWMMWW design criteria. Chemical and treatment efficacy of the bioretention soil mix was not included in our scope of services. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. The conclusions, recommendations, and opinions presented in this report are based on our professional knowledge, judgment, laboratory test results, and experience. No warranty or other conditions, express or implied, should be understood. Any electronic form, facsimile or hard copy of the original document (email, text, table and/or figure), if provided, and any attachments should be considered a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record. File No. 0000-001-00 File No. 0482-051-03 APPENDIX A Laboratory Test Results 0482-051-03 Date Exported: 06/24/16 U.S. STANDARD SIEVE SIZE 3â€ 1.5â€ 3/4â€ 3/8â€ #4 #10 #20 #40 #60 #100 #200 100 90 80 70 60 PERCENT PASSING BY WEIGHT 50 40 30 20 10 0 Proposed Pole Storage Yard 1000 100 10 1 0.1 0.01 0.001 Sieve Analysis Results GRAIN SIZE IN MILLIMETERS Arlington, WA GRAVEL SAND COBBLES SILT OR CLAY COARSE FINE COARSE MEDIUM FINE Depth Moisture Symbol Sample (feet) (%) Soil Description No Compost N/A 5.4 Poorly graded sand with gravel (SP) Figure A 10% Compost N/A 8.0 Poorly graded sand with gravel and organic matter (SP) 15% Compost N/A 8.2 Poorly graded sand with silt and gravel and organic matter (SP-SM) 20% Compost N/A 12.1 Poorly graded sand with gravel and organic matter (SP) -2 Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they were performed,andshouldnotbe interpreted as representativeofanyothersamples obtained atother times,depthsorlocations,orgenerated by separate operationsorprocesses. Thegrainsizeanalysis results were obtained in general accordancewithASTMD6913. MOISTURE CONTENT (%) 0 5 10 15 20 25 30 140 135 130 125 (pcf) 120 DRY DENSITY 115 100% Saturation 110 (Gs=2.65) 105 100 Optimum Maximum Depth Moisture Dry Density Symbol Sample (feet) Soil Description (%) (pcf) Corrected 10% 9.9 127.1 N/A 10 Percent Compost/Gravel Borrow Mix Uncorrected Compost 13.5 116.0 Note: This report may not be reproduced, except in full, without written approval Compaction Test Results of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they were performed, and should not be interpreted as 10% Compost Mix representative of any other samples obtained at other times, depths or locations,orgenerated by separate operationsorprocesses. Proposed Pole Storage Yard The Proctor results were obtained in general accordance with Exported: 06/27/16 ASTMD1557. Arlington, WA Date -03 051 Figure A-3 0482- MOISTURE CONTENT (%) 0 5 10 15 20 25 30 140 135 130 125 (pcf) 120 DRY DENSITY 115 100% Saturation 110 (Gs=2.65) 105 100 Optimum Maximum Depth Moisture Dry Density Symbol Sample (feet) Soil Description (%) (pcf) Corrected 15% 9.1 126.0 N/A 15 Percent Compost/Gravel Borrow Mix Uncorrected Compost 12.5 114.0 Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific Compaction Test Results sample on which they were performed, and should not be interpreted as 15% Compost Mix representative of any other samples obtained at other times, depths or locations,orgenerated by separate operationsorprocesses. Proposed Pole Storage Yard The Proctor results were obtained in general accordance with Exported: 06/30/16 ASTMD1557. Arlington, WA Date -03 051 Figure A-4 0482- MOISTURE CONTENT (%) 0 5 10 15 20 25 125 120 100% 115 Saturation (Gs=2.65) (pcf) 110 DRY DENSITY 105 100 95 Optimum Maximum Depth Moisture Dry Density Symbol Sample (feet) Soil Description (%) (pcf) Corrected 20% 10.6 120.0 Grab Poorly graded sand with gravel and organic matter (SP) Uncorrected Compost 13.7 109.6 Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific Compaction Test Results sample on which they were performed, and should not be interpreted as 20% Compost Mix representative of any other samples obtained at other times, depths or locations,orgenerated by separate operationsorprocesses. Proposed Pole Storage Yard The Proctor results were obtained in general accordance with Exported: 07/08/16 ASTMD1557. Arlington, WA Date -03 051 Figure A-5 0482- Boring #: N/A Sample #: 10% Mix Depth: N/A Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 116.0 Optimum Moisture Content (%) 13.5 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 85.0 Sample Prepared Moisture Content (%) 13.5 Sample length (in): 8.00 (cm): 20.32 (L) Remolded Compaction (%) 85.3 Sample volume (in3): 226.19 (cm3): 3707.33 Sample Back Calculated After Test 86.4 Compaction (%) Sample volume (ft3): 0.1309 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 80.00 81.00 1.00 15.2 50.0 233 1.18E-03 0.066 1.79E-02 22.0 0.9547 1.70E-0224.1 2 80.00 81.00 1.00 15.2 50.0 234 1.17E-03 0.066 1.78E-02 22.0 0.9547 1.70E-0224.0 3 80.00 81.00 1.00 15.2 50.0 232 1.18E-03 0.066 1.80E-02 22.0 0.9547 1.71E-0224.2 4 80.00 81.00 1.00 15.2 50.0 233 1.18E-03 0.066 1.79E-02 22.0 0.9547 1.70E-0224.1 avg 1.79E-02 1.70E-02 24.1 1 80.00 81.00 1.00 15.2 100.0 469 1.17E-03 0.066 1.78E-02 22.0 0.9547 1.69E-02 24.0 2 80.00 81.00 1.00 15.2 100.0 473 1.16E-03 0.066 1.76E-02 22.0 0.9547 1.68E-02 23.8 3 80.00 81.00 1.00 15.2 100.0 473 1.16E-03 0.066 1.76E-02 22.0 0.9547 1.68E-02 23.8 4 80.00 81.00 1.00 15.2 100.0 471 1.16E-03 0.066 1.77E-02 22.0 0.9547 1.69E-02 23.9 5 80.00 81.00 1.00 15.2 100.0 473 1.16E-03 0.066 1.76E-02 22.1 0.9524 1.67E-02 23.7 6 80.00 81.00 1.00 15.2 250.0 1207 1.14E-03 0.066 1.73E-02 22.1 0.9524 1.64E-02 23.2 avg 1.76E-02 1.67E-02 23.7 Total avg 1.77E-02 1.69E-02 23.9 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 10% Compost Mix at 85% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-6 Manual for Western Washington (SWMMWW). Boring #: 10% Compost Sample #: 10% Mix (2) Depth: Grab Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 116.0 Sample area (in2): 28.274 (cm2): 182.43 (A) Optimum Moisture Content (%) 13.5 Target Relative Density (%) 90.0 Sample length (in): 9.00 (cm): 22.86 (L) Sample Prepared Moisture Content (%) 13.5 3 3 Remolded Compaction (%) 90.3 Sample volume (in): 254.47 (cm ): 4170.75 Sample Back Calculated After Test 90 Sample volume (ft3): 0.1473 Compaction (%) Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 79.50 81.80 2.30 15.2 10.0 117 4.69E-04 0.151 3.10E-03 19.4 1.0169 3.14E-034.5 2 79.50 81.80 2.30 15.2 10.0 121 4.53E-04 0.151 2.99E-03 19.4 1.0169 3.04E-034.3 3 79.50 81.80 2.30 15.2 10.0 119 4.61E-04 0.151 3.04E-03 19.4 1.0169 3.09E-034.4 4 79.50 81.80 2.30 15.2 10.0 112 4.89E-04 0.151 3.23E-03 19.4 1.0169 3.28E-034.7 5 79.50 81.80 2.30 15.2 20.0 217 5.05E-04 0.151 3.34E-03 19.4 1.0169 3.39E-034.8 6 79.50 81.80 2.30 15.2 20.0 210 5.22E-04 0.151 3.45E-03 19.5 1.0144 3.49E-035.0 avg 3.19E-03 3.24E-03 4.6 7 79.50 81.80 2.30 15.2 20.0 205 5.35E-04 0.151 3.53E-03 19.5 1.0144 3.58E-035.1 8 79.50 81.80 2.30 15.2 20.0 214 5.12E-04 0.151 3.39E-03 19.5 1.0144 3.43E-034.9 9 79.50 81.80 2.30 15.2 20.0 211 5.20E-04 0.151 3.43E-03 19.5 1.0144 3.48E-034.9 10 79.50 81.80 2.30 15.2 40.0 436 5.03E-04 0.151 3.32E-03 19.4 1.0169 3.37E-034.8 11 79.50 81.80 2.30 15.2 40.0 449 4.88E-04 0.151 3.23E-03 19.4 1.0169 3.28E-034.6 12 79.50 81.80 2.30 15.2 40.0 449 4.88E-04 0.151 3.23E-03 19.4 1.0169 3.28E-034.6 13 79.50 81.80 2.30 15.2 40.0 455 4.82E-04 0.151 3.18E-03 19.4 1.0169 3.23E-034.6 avg 3.33E-03 3.37E-03 4.8 14 79.50 81.80 2.30 15.2 40.0 478 4.59E-04 0.151 3.03E-03 19.3 1.0195 3.08E-034.4 15 79.50 81.80 2.30 15.2 40.0 469 4.68E-04 0.151 3.09E-03 19.2 1.0220 3.15E-034.5 16 79.50 81.80 2.30 15.2 40.0 479 4.58E-04 0.151 3.03E-03 19.2 1.0220 3.09E-034.4 avg 3.05E-03 3.11E-03 4.4 Total avg 3.19E-03 3.24E-03 4.6 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 10% Compost Mix at 90% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-7 Manual for Western Washington (SWMMWW). Constant Head Hydraulic Conductivity Test Project: Arlington Pole Storage Yard Date: 6/28/16 Project #: 0482-051-03 Tested by: S. Swenson Boring #: N/A Sample #: 15% Mix Depth: N/A Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 114.0 Optimum Moisture Content (%) 12.5 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 85.0 Sample Prepared Moisture Content (%) 13.0 Sample length (in): 9.00 (cm): 22.86 (L) Remolded Compaction (%) 84.5 Sample volume (in3): 254.47 (cm3): 4170.75 Sample Back Calculated After Test 91.2 Compaction (%) Sample volume (ft3): 0.1473 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 80.60 81.60 1.00 15.2 10.0 212 2.59E-04 0.066 3.93E-03 20.7 0.9850 3.86E-035.5 2 80.60 81.60 1.00 15.2 10.0 215 2.55E-04 0.066 3.88E-03 20.7 0.9850 3.81E-035.4 3 80.60 81.60 1.00 15.2 10.0 219 2.50E-04 0.066 3.80E-03 20.7 0.9850 3.74E-035.3 4 80.60 81.60 1.00 15.2 10.0 210 2.61E-04 0.066 3.97E-03 20.7 0.9850 3.90E-035.5 5 80.60 81.60 1.00 15.2 10.0 209 2.62E-04 0.066 3.99E-03 20.7 0.9850 3.92E-035.6 6 80.60 81.60 1.00 15.2 10.0 209 2.62E-04 0.066 3.99E-03 21.1 0.9755 3.88E-035.5 7 80.60 81.60 1.00 15.2 10.0 215 2.55E-04 0.066 3.88E-03 21.2 0.9732 3.76E-035.3 avg 3.92E-03 3.84E-03 5.4 1 80.60 81.60 1.00 15.2 20.0 421 2.60E-04 0.066 3.96E-03 21.0 0.9779 3.86E-035.5 2 80.60 81.60 1.00 15.2 20.0 401 2.73E-04 0.066 4.16E-03 20.7 0.9850 4.09E-035.8 3 80.60 81.60 1.00 15.2 20.0 440 2.49E-04 0.066 3.79E-03 20.7 0.9850 3.72E-035.3 4 80.60 81.60 1.00 15.2 20.0 423 2.59E-04 0.066 3.94E-03 21.0 0.9779 3.84E-035.4 avg 3.96E-03 3.88E-03 5.5 Total avg 3.94E-03 3.86E-03 5.5 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 15% Compost Mix at 85% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-8 Manual for Western Washington (SWMMWW). Boring #: Sample #: 15% Mix Depth: Grab Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 114.0 Optimum Moisture Content (%) 12.5 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 90.0 Sample Prepared Moisture Content (%) 12.5 Sample length (in): 9.00 (cm): 22.86 (L) Remolded Compaction (%) 90 Sample volume (in3): 254.47 (cm3): 4170.75 Sample Back Calculated After Test 90.2 Compaction (%) Sample volume (ft3): 0.1473 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 80.20 81.90 1.70 15.2 10.0 393 1.39E-04 0.112 1.25E-03 19.3 1.0195 1.27E-031.8 2 80.20 81.90 1.70 15.2 10.0 408 1.34E-04 0.112 1.20E-03 19.2 1.0220 1.23E-031.7 3 80.20 81.90 1.70 15.2 10.0 393 1.39E-04 0.112 1.25E-03 19.2 1.0220 1.27E-031.8 4 80.20 81.90 1.70 15.2 10.0 374 1.47E-04 0.112 1.31E-03 19.2 1.0220 1.34E-031.9 5 80.20 81.90 1.70 15.2 10.0 382 1.43E-04 0.112 1.28E-03 19.2 1.0220 1.31E-031.9 6 80.20 81.90 1.70 15.2 10.0 380 1.44E-04 0.112 1.29E-03 19.2 1.0220 1.32E-031.9 7 80.20 81.90 1.70 15.2 10.0 374 1.47E-04 0.112 1.31E-03 19.2 1.0220 1.34E-031.9 8 80.20 81.90 1.70 15.2 10.0 372 1.47E-04 0.112 1.32E-03 19.2 1.0220 1.34E-031.9 9 80.20 81.90 1.70 15.2 10.0 377 1.45E-04 0.112 1.30E-03 19.2 1.0220 1.33E-031.9 10 80.20 81.90 1.70 15.2 10.0 367 1.49E-04 0.112 1.34E-03 19.2 1.0220 1.36E-031.9 11 80.20 81.90 1.70 15.2 10.0 369 1.49E-04 0.112 1.33E-03 19.2 1.0220 1.35E-031.9 12 80.20 81.90 1.70 15.2 10.0 371 1.48E-04 0.112 1.32E-03 19.2 1.0220 1.35E-031.9 avg 1.29E-03 1.32E-03 1.9 1 80.20 81.90 1.70 15.2 67.0 2442 1.50E-04 0.112 1.34E-03 21.0 0.9779 1.31E-03 1.9 2 80.20 81.90 1.70 15.2 114.0 4029 1.55E-04 0.112 1.39E-03 20.7 0.9850 1.36E-03 1.9 avg 1.37E-03 1.34E-03 1.9 Total avg 1.33E-03 1.33E-03 1.9 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 15% Compost Mix at 90% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-9 Manual for Western Washington (SWMMWW). Constant Head Permeability Test data Project: Arlington Pole Storage Yard Date: 6/28/16 Project #: 0482-051-03 Tested by: S. Swenson Boring #: N/A Sample #: 20% Mix Depth: N/A Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 109.6 Optimum Moisture Content (%) 13.7 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 85.0 Sample Prepared Moisture Content (%) 13.7 Sample length (in): 9.00 (cm): 22.86 (L) Remolded Compaction (%) 84.7 Sample volume (in3): 254.47 (cm3): 4170.75 Sample Back Calculated After Test 85.4 Compaction (%) Sample volume (ft3): 0.1473 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 79.90 81.90 2.00 15.2 5.0 176 1.56E-04 0.132 1.18E-03 20.8 0.9826 1.16E-03 1.6 2 79.90 81.90 2.00 15.2 5.0 185 1.48E-04 0.132 1.13E-03 20.9 0.9803 1.10E-03 1.6 3 79.90 81.90 2.00 15.2 5.0 158 1.73E-04 0.132 1.32E-03 20.8 0.9826 1.29E-03 1.8 4 79.90 81.90 2.00 15.2 5.0 154 1.78E-04 0.132 1.35E-03 20.9 0.9803 1.32E-03 1.9 5 79.90 81.90 2.00 15.2 5.0 153 1.79E-04 0.132 1.36E-03 20.9 0.9803 1.33E-03 1.9 avg 1.26E-03 1.24E-03 1.8 1 79.90 81.90 2.00 15.2 10.0 350 1.57E-04 0.132 1.19E-03 21.0 0.9779 1.16E-031.6 2 79.90 81.90 2.00 15.2 10.0 337 1.63E-04 0.132 1.24E-03 20.9 0.9803 1.21E-031.7 3 79.90 81.90 2.00 15.2 10.0 338 1.62E-04 0.132 1.23E-03 21.1 0.9755 1.20E-031.7 4 79.90 81.90 2.00 15.2 10.0 342 1.60E-04 0.132 1.22E-03 21.0 0.9779 1.19E-031.7 5 79.90 81.90 2.00 15.2 10.0 340 1.61E-04 0.132 1.23E-03 21.1 0.9755 1.19E-031.7 6 79.90 81.90 2.00 15.2 10.0 335 1.64E-04 0.132 1.24E-03 21.1 0.9755 1.21E-031.7 7 79.90 81.90 2.00 15.2 10.0 337 1.63E-04 0.132 1.24E-03 21.1 0.9755 1.20E-031.7 8 79.90 81.90 2.00 15.2 10.0 341 1.61E-04 0.132 1.22E-03 21.1 0.9755 1.19E-031.7 9 79.90 81.90 2.00 15.2 10.0 336 1.63E-04 0.132 1.24E-03 21.2 0.9732 1.20E-031.7 10 79.90 81.90 2.00 15.2 10.0 339 1.62E-04 0.132 1.23E-03 21.2 0.9732 1.19E-031.7 avg 1.23E-03 1.20E-03 1.7 Total avg 1.25E-03 1.22E-03 1.7 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 20% Compost Mix at 85% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-10 Manual for Western Washington (SWMMWW). Appendix D â€“ Well Head Protection Zones Stormwater Site Plan Appendix D Arlington Electrical Equipment &Pole Storage Yard July, 2016 Haller Park Wellfield 4 3 2 1 6 9 10 11 12 7 16 15 14 13 18 Airport Well Project Site 21 22 23 24 19 Area of project site being developed. 28 27 26 25 30 33 34 35 36 31 FIGURE 1 Wells 1-Year-Buffer Wellhead Protection Zone 5-Year 6-Month 5-Year-Buffer WELLHEAD PROTECTION ZONES 6-Month-Buffer 10-Year 1-Year 10-Year-Buffer CITY OF ARLINGTON Feet 0 2,000 Appendix E â€“ Soil Map Stormwater Site Plan Appendix E Arlington Electrical Equipment &Pole Storage Yard July, 2016 Hydrologic Soil Groupâ€”Snohomish County Area, Washington (Arlington Temporary Storage Yard) 122Â° 9' 12'' 122Â° 8' 19'' 563000 563100 563200 563300 563400 563500 563600 563700 563800 563900 564000 48Â° 9' 35'' 48Â° 9' 35'' 5334400 5334400 180th St 59th Dr Bovee Ln 5334300 5334300 Upland Dr 72 5334200 5334200 74 18 5334100 Hillside Ct 5334100 30 39 59th Ave 5334000 5334000 5333900 5333900 67th Ave Highland View Dr 5333800 5333800 5333700 5333700 48Â° 9' 11'' 48Â° 9' 11'' 563000 563100 563200 563300 563400 563500 563600 563700 563800 563900 564000 Map Scale: 1:5,280 if printed on A size (8.5" x 11") sheet. Meters 122Â° 9' 13'' 0 50 100 200 300 122Â° 8' 19'' Feet 0 250 500 1,000 1,500 Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 1 of 4 Hydrologic Soil Groupâ€“Snohomish County Area, Washington (Arlington Temporary Storage Yard) MAP LEGEND MAP INFORMATION Area of Interest (AOI) Map Scale: 1:5,280 if printed on A size (8.5" Ã— 11") sheet. Area of Interest (AOI) The soil surveys that comprise your AOI were mapped at 1:24,000. Soils Soil Map Units Warning: Soil Map may not be valid at this scale. Soil Ratings Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line A placement. The maps do not show the small areas of contrasting A/D soils that could have been shown at a more detailed scale. B Please rely on the bar scale on each map sheet for accurate map B/D measurements. C Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov C/D Coordinate System: UTM Zone 10N NAD83 D This product is generated from the USDA-NRCS certified data as of Not rated or not available the version date(s) listed below. Political Features Soil Survey Area: Snohomish County Area, Washington Cities Survey Area Data: Version 7, Jun 29, 2012 Water Features Date(s) aerial images were photographed: 7/24/2006 Streams and Canals The orthophoto or other base map on which the soil lines were Transportation compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting Rails of map unit boundaries may be evident. Interstate Highways US Routes Major Roads Local Roads Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 2 of 4 Hydrologic Soil Groupâ€“Snohomish County Area, Washington Arlington Temporary Storage Yard Hydrologic Soil Group Hydrologic Soil Groupâ€” Summary by Map Unit â€” Snohomish County Area, Washington (WA661) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 18 Everett gravelly sandy loam, 8 A 5.4 6.8% to 15 percent slopes 30 Lynnwood loamy sand, 0 to 3 A 61.2 76.7% percent slopes 39 Norma loam B/D 12.5 15.7% 72 Tokul gravelly loam, 0 to 8 C 0.3 0.3% percent slopes 74 Tokul gravelly loam, 15 to 25 C 0.3 0.4% percent slopes Totals for Area of Interest 79.8 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Groupâ€“Snohomish County Area, Washington Arlington Temporary Storage Yard Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 4 of 4 Appendix F â€“ Operations and Maintenance Manual Stormwater Site Plan Appendix F Arlington Electrical Equipment &Pole Storage Yard July, 2016 Drip pan NOT TO SCALE Figure IV-2.2.2 Drip Pan Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. Drip pan within rails NOT TO SCALE Figure IV-2.2.3 Drip Pan Within Rails Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.4 Loading Dock with Door Skirt Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.5 Loading Dock with Overhang Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.8 Secondary Containment System Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. Lid NOT TO SCALE Figure IV-2.2.9 Locking System for Drum Lid Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.10 Covered and Bermed Containment Area Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. *Note that the secondary containment is not shown in this figure NOT TO SCALE Figure IV-2.2.11 Mounted Container - with Drip Pan Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.13 Covered Storage Area for Bulk Solids (include berm if needed) D E P A R T M E N T O F Revised December 2015 ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.14 Material Covered with Plastic Sheeting Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. Geotechnical Engineering Services Proposed Pole Storage Yard Arlington Site Development Arlington, Washington for Snohomish County PUD No. 1 May 4, 2016 Geotechnical Engineering Services Proposed Pole Storage Yard Arlington Site Development Arlington, Washington for Snohomish County PUD No. 1 May 4, 2016 8410 154th Avenue NE Redmond, Washington 98052 425.861.6000 Table of Contents INTRODUCTION ........................................................................................................................................................... 1 Project Description ............................................................................................................................................... 1 Purpose and Scope .............................................................................................................................................. 1 FIELD EXPLORATION AND LABORATORY TESTING ................................................................................................. 1 Field Explorations ................................................................................................................................................. 1 Laboratory Testing ............................................................................................................................................... 1 SITE CONDITIONS ....................................................................................................................................................... 2 Surface Conditions............................................................................................................................................... 2 Geology ................................................................................................................................................................. 2 Subsurface Conditions ........................................................................................................................................ 2 Groundwater Conditions ...................................................................................................................................... 2 CONCLUSIONS AND RECOMMENDATIONS .............................................................................................................. 3 Summary of Key Geotechnical Issues ................................................................................................................ 3 Earthquake Engineering ...................................................................................................................................... 4 2012 IBC Seismic Design Information ........................................................................................................ 4 Liquefaction ................................................................................................................................................... 4 Lateral Spreading .......................................................................................................................................... 5 Pole Storage Yard Gravel Surfacing .................................................................................................................... 5 Pavement Recommendations ............................................................................................................................. 6 Subgrade Preparation ................................................................................................................................... 6 New Hot Mix Asphalt Pavement ................................................................................................................... 6 Portland Cement Concrete Pavement ......................................................................................................... 7 Asphalt-Treated Base .................................................................................................................................... 7 Earthwork ............................................................................................................................................................. 8 Clearing and Site Preparation ...................................................................................................................... 8 Subgrade Preparation ................................................................................................................................... 8 Structural Fill ................................................................................................................................................. 9 Excavations ....................................................................................................................................................... 10 Temporary Cut Slopes ................................................................................................................................ 11 Utility Trenches ........................................................................................................................................... 11 Sedimentation and Erosion Control .......................................................................................................... 12 INFILTRATION FACILITIES ........................................................................................................................................ 12 Recommended Additional Geotechnical Services .......................................................................................... 13 LIMITATIONS ............................................................................................................................................................. 13 REFERENCES ............................................................................................................................................................ 14 May 4, 2016 | Page i File No. 0482-051-03 Table of Contents (continued) LIST OF FIGURES Figure 1. Vicinity Map Figure 2. Site Plan Figure 3. Compaction Criteria for Trench Backfill Figure 4. Groundwater Level Data APPENDICES Appendix A. Field Exploration Figure A-1. Key to Exploration Logs Figures A-2 through A-7. Log of Borings Figures A-8 through A-15. Log of Test Pits Appendix B. Laboratory Testing Figures B-1 and B-2. Sieve Analysis Results Appendix C. Report Limitations and Guidelines for Use May 4, 2016 | Page ii File No. 0482-051-03 INTRODUCTION This report contains the results of our geotechnical engineering services for use in the design and construction of the proposed Pole Storage Yard at the Districtâ€™s Arlington Site located between 172nd Street NE and 180th Street NE off of 59th Avenue NE in Arlington, Washington. The project location is shown in the Vicinity Map, Figure 1. The layout of the conceptual site improvements is shown relative to surrounding physical features in the Site Plan, Figure 2. Project Description We understand that a portion of the site is being developed for a Pole Storage Yard to store treated poles and transformers. Development of the pole storage yard will include constructing gravel laydown areas, asphalt paved access roads and transformer storage areas, and installation of a water line. We understand that design of the local office building, solar array area, additional roadways, and the substation will occur at a later date; therefore, this report does not include recommendations for these portions of the project. Purpose and Scope The purpose of our engineering services is to provide geotechnical recommendations for design of the proposed Pole Storage Yard. Geotechnical engineering recommendations for design of the remaining portions of the site are not included in this report, but will be provided at a later stage during development of the site. Our geotechnical engineering services were completed in accordance with our proposal for the project, dated March 10, 2016 and our on-call agreement with the District. FIELD EXPLORATION AND LABORATORY TESTING Field Explorations The subsurface conditions at the site were evaluated by drilling six borings (B-1 through B-6) and by excavating eight test pits (TP-1 through TP-8). The borings were advanced to depths of 26Â½ to 51Â½ feet below existing site grade and the test pits were excavated to depths ranging from 11 to 12 feet below the existing ground surface (bgs). Test pit TP-4 was completed within the footprint of the proposed Pole Storage Yard to a depth of 12 feet. Boring B-1 was completed within 150 feet of the Pole Storage Yard to a depth of 26Â½ feet. The approximate locations of the explorations are shown in the Site Plan, Figure 2. A detailed description of the field explorations is presented in Appendix A. Laboratory Testing Soil samples were collected from the explorations, taken to our laboratory and evaluated to confirm or modify field classifications, as well as to evaluate engineering properties of the soil. Representative samples were selected for laboratory testing consisting of determination of moisture content, grain size distribution, percent passing U.S. No. 200 sieve, organic content, and cation-exchange capacity (CEC). A description of the laboratory testing and the test results are presented in Appendix B. May 4, 2016 | Page 1 File No. 0482-051-03 SITE CONDITIONS Surface Conditions The Arlington property is about 25.6 acres and is relatively flat and currently undeveloped. The property ranges from about Elevation 140 feet on the northeast corner to Elevation 131 feet on the southwest corner. The proposed Pole Storage Yard occupies about 1.4 acres and is relatively flat with the ground surface elevation between about 135 to 136 feet. Vegetation on the property consists of mowed blackberry brambles and a few large deciduous and conifer trees. An old barn is located in the center of the property. The locations of surrounding property features with respect to the proposed Pole Storage Yard improvements are shown in the Site Plan, Figure 2. Geology Our review of the U.S. Geological Survey map, Geologic Map of the Arlington West 7.5-Minute Quadrangle Snohomish County, Washington by James P. Minard indicates that surficial soils at the Arlington property consist primarily of recessional outwash deposits of the Marysville Sand Member. The Marysville Sand Member typically consists of stratified outwash sand with occasional gravel, and isolated areas of silt and clay. The sediments were deposited by meltwater from the stagnating and receding Vashon glacier and are typically medium dense/stiff. We observed recessional outwash deposits in each of the explorations completed on the property. Subsurface Conditions Based on the explorations completed on the property, the subsurface conditions generally consist of a thin layer of silty sand overlying recessional outwash deposits. At the surface, we observed 4 to 8 inches of topsoil with roots overlying either fill or native recessional outwash deposits. The topsoil thickness was measured by hand to be 4 inches at four locations and 8 inches in one location within the footprint of the proposed Pole Storage Yard. A 2-foot-thick layer of disturbed native soils was observed in test pits TP-2 through TP-8. A 4-foot-thick layer of disturbed native soils or fill was observed in boring B-4. The fill or disturbed native soils consist of loose silty sand with occasional gravel. The fill/disturbed native soils overlie native glacially deposited recessional outwash (Marysville Sand Member) consisting of medium dense to dense sand with variable silt and gravel content. The recessional outwash soils were observed to the depth explored. Groundwater Conditions Groundwater observed at the time of the explorations generally ranged from 7Â½ to 12 feet bgs. Groundwater was also measured in two monitoring wells installed in borings B-3 and B-4, and data loggers were placed in the wells to record groundwater elevation data after June 25, 2012. A summary of the groundwater elevations observed at the time of drilling, and the minimum and maximum measured elevations in the monitoring wells is summarized in Table 1. Measurements from the data loggers installed within borings B-3 and B-4 are shown graphically in Figure 4. Groundwater monitoring wells B-3 and B-4 are approximately 935 feet apart and the water elevation from B-3 was 5.24 feet lower than the water elevation in B-4 February 9, 2016. The water levels in the two wells indicate a two-dimensional gradient of 0.005 feet per foot, comparable to the Vashon Recessional gradient. May 4, 2016 | Page 2 File No. 0482-051-03 Based on this estimated gradient and the depth to groundwater measurements, we anticipate that seasonal high groundwater levels below the proposed Pole Storage Yard will be greater than 5 feet below existing grade. TABLE 1. SUMMARY OF GROUNDWATER CONDITIONS Depth to Groundwater Approximate Groundwater Elevation Exploration (feet) (feet) B-1 11 126 B-2 11 121 B-3 (MW) 8 (min) to 19 (max) 115 (min) to 126 (max) B-4 (MW) 4 (min) to 16 (max) 119 (min) to 131 (max) B-5 8 128Â½ B-6 7Â½ 129 TP-1 11 121 TP-2 9 123 TP-3 10 124 TP-4 12 123 TP-5 9 125 TP-6 9 129 TP-7 9 127 TP-8 8 127 Notes: 1. The ground surface elevations at the exploration locations were estimated from the base survey map and are approximate. 2. Groundwater measurements from data loggers installed within borings B-3 and B-4 are shown graphically in Figure 4. CONCLUSIONS AND RECOMMENDATIONS Summary of Key Geotechnical Issues Based on the results of our subsurface exploration program, it is our opinion that the proposed Pole Storage Yard project for the Arlington Site Development may be constructed satisfactorily as planned with respect to geotechnical elements. The key geotechnical issues for the project include: â– The site is designated as seismic Site Class D per the 2012 International Building Code (IBC) (IBC, 2012). â– New hot-mix asphalt (HMA) pavement sections should consist of at least 3 inches HMA over 4 inches of base course in light-duty pavement areas (automobile parking) and at least 4 inches HMA over 8 inches of base course in heavy-duty pavement areas (access roads, etc.). Thicker pavement sections may be required depending on actual equipment and traffic loads. Alternatively the City of Arlington design standards should be met, if required. â– The recessional outwash soils observed generally contain a low to moderate percentage of fines. The near surface soils (upper 4 feet, typically) contain a higher percentage of fines. The on-site soils May 4, 2016 | Page 3 File No. 0482-051-03 may be used as structural fill during dry weather conditions (typically June through September) provided the soil is properly moisture conditioned. Imported Gravel Borrow may be required for use as structural fill during wet weather conditions and during the wet season (typically October through May) if the on-site soils cannot be properly moisture conditioned and compacted. â– Based on grain-size analysis and the 2012 Stormwater Management Manual for Western Washington (SWMMWW), the estimated long-term saturated hydraulic conductivity values range from about 1 (silty sand) to 8 (clean sand) inches per hour. Based on limited CEC testing, the topsoil appears to meet the SWMMWW requirements for bio-treatment, but the recessional outwash sand do not. These geotechnical issues and other considerations are discussed further, and recommendations pertaining to the geotechnical aspects of the project are presented in the following sections. Earthquake Engineering 2012 IBC Seismic Design Information We recommend the 2012 IBC parameters for Site Class, short period spectral response acceleration (SS), 1-second period spectral response acceleration (S1), and Seismic Coefficients FA and FV presented in Table 2. TABLE 2. 2012 IBC SEISMIC PARAMETERS 2012 IBC Parameter Recommended Value Site Class D Short Period Spectral Response Acceleration, SS (percent g) 107.1 1-Second Period Spectral Response Acceleration, S1 (percent g) 41.7 Seismic Coefficient, FA 1.072 Seismic Coefficient, FV 1.583 Notes: Based on site coordinates 48.15697Â°N, 122.14559Â°W, and Site Class D using the USGS online Design Maps. Liquefaction Liquefaction is a phenomenon where soils experience a rapid loss of internal strength as pore water pressures increase in response to strong ground shaking. The increased pore water pressure may temporarily meet or exceed soil overburden pressures to produce conditions that allow soil and water to flow, deform, or erupt from the ground surface. Ground settlement, lateral spreading and/or sand boils may result from soil liquefaction. Structures supported on or within liquefied soils may suffer foundation settlement or lateral movement that can be damaging to the structure. The evaluation of liquefaction potential is a complex procedure and is dependent on numerous site parameters, including soil grain size, soil density, site geometry, static stresses, and the design ground acceleration. Typically, the liquefaction potential of a site is evaluated by comparing the cyclic shear stress ratio (the ratio of the cyclic shear stress to the initial effective overburden stress) induced by an earthquake to the cyclic shear stress ratio required to cause liquefaction. Estimation of the cyclic shear stress required to initiate liquefaction and the cyclic shear stress initiated by a design earthquake were completed using the empirical method developed by Seed et al. (1985) as revised at the National Control for Earthquake May 4, 2016 | Page 4 File No. 0482-051-03 Engineering Research (NCEER) workshop in 1997 (Youd, et al., 2001). The cyclic shear stress ratio required to cause liquefaction at the site was estimated using empirical procedures based on correlations from the standard penetration tests (SPTs). Estimated ground settlement resulting from earthquake-induced liquefaction was analyzed using an empirical procedure that relates settlement to average SPT N-values. A design earthquake with a magnitude of 7.0 and a peak horizontal acceleration of 0.28g (28 percent of the acceleration due to gravity) was used for our analysis. This analysis also assumes a level ground surface. The analysis indicates that isolated zones in the medium dense sand deposits have a moderate to high potential for liquefaction during a design earthquake event. These zones appear to be discontinuous and are generally located between the depths of 20 to 50 feet bgs. The liquefaction potential is low during an event with a lower level of ground shaking. Our analyses indicate that settlement caused by liquefaction of the saturated medium dense sand layers during a design earthquake could be on the order of 1 to 2 inches. Because of the discontinuous nature of the potentially liquefiable sand layers and random nature of liquefaction, differential settlement may be on the same order as the total settlement. Lateral Spreading Lateral spreading occurs when the shear strength of the liquefied soil is incrementally exceeded by the lateral inertial forces induced during an earthquake. The result of lateral spreading is typically horizontal movement of non-liquefied soils located above liquefied soils. Lateral spreading generally develops in areas where sloping ground is present or near a free face. If liquefaction were to occur within the sand deposits underlying the site, we anticipate there would be a low potential for lateral spreading to occur within the medium dense sand layers since the ground surface at the site is relatively flat. Pole Storage Yard Gravel Surfacing We understand that the Pole Storage Yard gravel surfacing will be used to infiltrate storm water as well as provide support for storage of materials and occasional truck traffic. The gravel surfacing will be underlain by an 18-inch-thick layer of engineered bioretention soil for treatment of infiltrated stormwater. We recommend that the bioretention soil mix be placed in 1-foot maximum lifts and compacted to at least 90 percent of the maximum dry density (MDD) prior to placing the gravel surfacing. Prior to placing the bioretention soil layer, the exposed subgrade should be compacted to at least 90 percent of the MDD or to the extent practical. Two recommended unpaved gravel surfacing options are provided in Table 3. We recommend that a moderate to high-strength reinforcement/separation/drainage geotextile, such as TenCate Mirafi RS380i, be used as part of the gravel surfacing section (Option 1) in lieu of placing a subbase layer. Alternatively, a light-weight separation/drainage geotextile, such as TenCate Mirafi 160N can be placed between the compacted bioretention soil mix and the compacted subbase layer (Option 2). The TenCate Mirafi RS380i geotextile will provide much better performance to support equipment and will provide a better working surface to facilitate placement and compaction of the crushed gravel surfacing. Some rutting and disturbance of the gravel surfacing may occur, depending on the traffic loading conditions, especially if the light-weight separation geotextile is used. Maintenance of the gravel surface including adding additional gravel and smoothing rutted areas will likely be necessary. May 4, 2016 | Page 5 File No. 0482-051-03 TABLE 3. RECOMMENDED UNPAVED GRAVEL SURFACING OPTIONS Material Option 1 Option 2 Crushed Gravel 8 inches 6 inches (AASHTO Grading No. 57) Gravel Borrow Subbase None 12 inches (WSDOT 9-03.14(1)) TenCate Mirafi RS380i TenCate Mirafi 160N Geotextile (or approved equivalent) (or approved equivalent) Bioretention Soil 18 inches 18 inches There are some specialized bioretention gravel/sand soil mixes on the market that can be compacted to 95 percent of the MDD, such as CU-Structural Soilâ„¢ (a proprietary mix). GeoEngineers can provide gravel surfacing recommendations for specialized bioretention soil mixes, if requested. Pavement Recommendations Subgrade Preparation We recommend the subgrade and subbase soils in new pavement areas be prepared and evaluated as described in the â€œEarthworkâ€ section of this report. If the subgrade soils are excessively loose or soft, it may be necessary to excavate localized areas and replace them with structural fill or crushed surfacing base course. All exposed subgrade soils should be compacted to at least 95 percent of the MDD under paved roads prior to placing imported subbase materials. Pavement subgrade conditions should be observed during construction and prior to placing the subbase materials in order to evaluate the presence of unsuitable subgrade soils and the need for over-excavation. New Hot Mix Asphalt Pavement We recommend the pavement sections presented in Table 4. Asphalt pavement should consist of HMA (PG 58-22) per Washington State Department of Transportation (WSDOT) Sections 5-04 and 9-03. Recommendations are provided for options to replace gravel with a moderate-strength geotextile. Alternatively, the site development may follow the City of Arlington typical roadway standards. The exposed subgrade soils should be compacted to at least 95 percent of the MDD per ASTM International (ASTM) Standard Practices Test Method D 1557. We recommend that a proof-roll of the exposed subgrade (prior to compacting), installation of geotextile (if applicable) and compacted base course be observed by a representative from our firm prior to paving. Soft or yielding areas observed during proof-rolling may require over-excavation and replacement with compacted structural fill. TABLE 4. RECOMMENDED PAVEMENT SECTIONS Option 1 Option 2 City of Arlington Std. Material Light-Duty Heavy-Duty Light-Duty Heavy-Duty Plan R-020 3 inches HMA (PG 58-22) 3 inches 4 inches 3 inches 4 inches (Class B) Asphalt-Treated Base (See ATB (See ATB None None 4 inches (WSDOT 4-06) Section Below) Section Below) May 4, 2016 | Page 6 File No. 0482-051-03 Option 1 Option 2 City of Arlington Std. Material Light-Duty Heavy-Duty Light-Duty Heavy-Duty Plan R-020 Base Course 4 inches 8 inches 8 inches 10 inches 6 inches (WSDOT 903.9(3)) Gravel Borrow Subbase 12 inches 12 inches None None None (WSDOT 9-03.14(1)) Mirafi RS380i Mirafi RS380i Reinforcement None None (or approved (or approved None Geotextile equivalent) equivalent) Notes: ASB â€“ Asphalt-treated base The pavement sections recommended above are based on our experience. Thicker asphalt sections may be needed based on the actual traffic data, truck loads, and intended use. All paved, unpaved and landscaped areas should be graded so surface drainage is directed to appropriate catch basins or infiltration areas. Portland Cement Concrete Pavement Portland cement concrete (PCC) sections should be considered for trash dumpster areas and where other concentrated heavy loads may occur. We recommend that these pavements consist of at least 6 inches of PCC over 6 inches of crushed surfacing base course. A thicker concrete section may be needed based on the actual traffic data. If the concrete pavement will have doweled joints, we recommend that the concrete thickness be increased by an amount equal to the diameter of the dowels. The base course, 12-inch subbase, and upper 12 inches of exposed subgrade soils should be compacted to at least 95 percent MDD. We recommend PCC pavements incorporate construction joints and/or crack control joints spaced at maximum distances of 12 feet apart, center-to-center, in both the longitudinal and transverse directions. Crack control joints may be created by placing an insert or groove into the fresh concrete surface during finishing, or by saw-cutting the concrete after it has initially set-up. We recommend the depth of the crack control joints be approximately one-fourth the thickness of the concrete; or about 1Â½ inches deep for the recommended concrete thickness of 6 inches. We also recommend the crack control joints be sealed with an appropriate sealant to help restrict water infiltration into the joints. Asphalt-Treated Base If pavements are constructed during the wet seasons, consideration may be given to covering the areas to be paved (subbase materials) with asphalt-treated base (ATB) for protection. Light-duty pavement areas should be surfaced with 3 inches of ATB, and heavy-duty pavement areas should be surfaced with 6 inches of ATB. Prior to placement of the final pavement sections, we recommend that the ATB surface be evaluated and areas of ATB pavement failure be removed and the subgrade repaired. If ATB is used, and is serviceable when final pavements are constructed, the crushed surfacing base course can be eliminated, and the design PCC or asphalt concrete pavement thickness can be placed directly over the ATB. May 4, 2016 | Page 7 File No. 0482-051-03 Earthwork Based on the subsurface soil conditions encountered in the explorations, we anticipate the soils at the site may be excavated using conventional construction equipment. The materials we encountered include fill and medium dense to dense outwash soils. Glacial soils in the area commonly contain cobbles and boulders that may be encountered during excavation. Accordingly, the contractor should be prepared to deal with boulders. Ideally, earthwork should be undertaken during extended periods of dry weather (June through September) when the surficial soils will be less susceptible to disturbance and provide better support for construction equipment. Dry weather construction will help reduce earthwork costs and increase the potential for reusing the fill and recessional outwash soils as structural fill. Clearing and Site Preparation Areas to be developed or graded should be cleared of surface and subsurface deleterious matter, including any debris, shrubs, trees and associated stumps and roots. Graded areas should be stripped of organic soils. Based on our observations, stripping depths on the order of 4 to 8 inches will be needed to remove organic topsoil and root mass materials in most areas. Deeper zones of organic soils should be expected in areas of dense vegetation or where large tree bulbs are located. The organic soils can be stockpiled and used later for landscaping purposes or may be spread over disturbed areas following completion of grading. If spread out, the organic strippings should be in a layer less than 1-foot-thick, should not be placed on slopes greater than 3H:1V (horizontal to vertical) and should be track-rolled to a uniformly compacted condition. Materials that cannot be used for landscaping or protection of disturbed areas should be removed from the project site. Subgrade Preparation Prior to placing new fills, subbase materials, or pavement base course materials, subgrade areas for pavements and gravel surfacing should be evaluated to locate any soft or pumping soils. Prior to proof-rolling, all unsuitable soils should be removed from below pavement areas. Proof-rolling can be completed using a piece of heavy tire-mounted equipment such as a loaded dump truck. During wet weather, the exposed subgrade areas should be probed to determine the extent of soft soils. If soft or pumping soils are observed, they should be removed and replaced with structural fill. Once approved, the subgrade areas should be recompacted to a firm or dense condition, if possible. The achievable degree of compaction will depend on when construction is performed. If the work is performed during dry weather conditions, we recommend that all subgrade areas below pavement be recompacted to at least 95 MDD in accordance with the ASTM D 1557 (Modified Proctor), or to at least 90 percent MDD under unpaved gravel areas. If the work is performed during wet weather conditions, it may not be possible to recompact the subgrade to 95 percent of the MDD. In this case, we recommend that the subgrade be compacted to the extent possible without causing undue weaving or pumping of the subgrade soils. Subgrade disturbance or deterioration could occur if the subgrade is wet and cannot be dried. If the subgrade deteriorates during compaction, it may become necessary to modify the compaction criteria or methods. May 4, 2016 | Page 8 File No. 0482-051-03 Structural Fill All fill, whether on-site or imported, supporting pavement areas or in utility trenches, should meet the criteria for structural fill presented below. The suitability of soil for use as structural fill depends on its gradation and moisture content. Materials Materials used to construct the Pole Storage Yard unpaved gravel surfacing, pavement areas, and to backfill utility trenches are classified as structural fill for the purpose of this report. Structural fill material quality varies depending upon its use as described below: â– Structural fill placed as backfill and subbase layer below the Pole Storage Yard, roadway areas, and to backfill utility trenches should consist of Imported Gravel Borrow as described in Section 9-03.14(1) of the 2012 WSDOT Standard Specifications, with the additional restriction that the fines content be limited to no more than 5 percent. However, if the native on-site soils can be properly moisture conditioned, and properly placed and compacted in thin lifts, it may be possible to reuse the sandy on-site soils in utility trenches and under proposed pavement and gravel surface areas below the subbase layer. â– Crushed gravel surfacing for the Pole Storage Yard should be in accordance with AASHTO Grading No. 57, or as approved in writing by the District. â– Structural fill placed as crushed surfacing base course below pavements should conform to Section 9-03.9 (3) of the 2012 WSDOT Standard Specifications. Reuse of On-site Soils The near surface on-site soils consist of recessional outwash sand below the topsoil and fill soils. On-site recessional outwash soils may be suitable for structural fill below parking areas and in utility trenches provided that the soil can be properly moisture conditioned and compacted. It may be necessary to import gravel borrow as described above to achieve adequate compaction, depending on weather conditions. The contractor should plan to cover and maintain all fill stockpiles with plastic sheeting if the fill is planned to be used as structural fill. The reuse of on-site soils is highly dependent on the skill of the contractor and schedule, and we will work with the design team and contractor to maximize the reuse of on-site soils during the wet and dry seasons. Fill Placement and Compaction Criteria Structural fill should be mechanically compacted to a firm, non-yielding condition. Structural fill should be placed in loose lifts not exceeding 12 inches in thickness when using heavy compaction equipment, or 6 inches when using light-weight hand operated compaction equipment. The actual thickness will be dependent on the structural fill material used, and the type and size of compaction equipment. Each lift should be conditioned to within 2 percent of the soils optimum moisture content and compacted to the specified density before placing subsequent lifts. Structural fill should be compacted to the following criteria: â– Structural fill in new pavement and hardscape areas, including the upper 2 feet of utility trench backfill under paved areas, should be compacted to at least 95 percent of the MDD estimated in accordance with ASTM D 1557. May 4, 2016 | Page 9 File No. 0482-051-03 â– Structural fill in planned unpaved gravel surfacing areas placed below the bio-retention soil layer should be compacted to at least 90 percent of the MDD estimated in accordance with ASTM D 1557. â– Utility trench backfill more than 2 feet below final subgrade should be compacted to at least 90 percent of the MDD, see Figure 3. â– Structural fill placed as crushed surfacing base course below pavements or as the unpaved gravel surfacing layer should be compacted to 95 percent of the MDD. â– Non-structural fill, such as fill placed in landscape areas, should be compacted to at least 90 percent of the MDD. Weather Considerations Disturbance of near surface soils should be expected, especially if earthwork is completed during periods of wet weather. During dry weather the soils will: (1) be less susceptible to disturbance; (2) provide better support for construction equipment; and (3) be more likely to meet the required compaction criteria. The wet weather season generally begins in October and continues through May in western Washington; however, periods of wet weather may occur during any month of the year. For earthwork activities during wet weather, we recommend that the following steps be taken: â– The ground surface in and around the work area should be sloped so that surface water is directed away from the work area. The ground surface should be graded so that areas of ponded water do not develop. Measures should be taken by the contractor to prevent surface water from collecting in excavations and trenches. Measures should be implemented to remove surface water from the work area. â– Earthwork activities should not take place during periods of moderate to heavy precipitation. â– Slopes with exposed soils should be covered with plastic sheeting. â– The contractor should take necessary measures to prevent on-site soils and soils to be used as fill from becoming wet or unstable. These measures may include the use of plastic sheeting, sumps with pumps, and grading. The site soils should not be left uncompacted and exposed to moisture. Sealing the surficial soils by rolling with a smooth-drum roller prior to periods of precipitation will help reduce the extent that these soils become wet or unstable. â– The contractor should cover all soil stockpiles that will be used as structural fill with plastic sheeting. Excavations The stability of open cut slopes is a function of soil type, groundwater seepage, slope inclination, slope height and nearby surface loads. The use of inadequately designed open cuts could impact the stability of adjacent work areas, existing utilities, and endanger personnel. The contractor performing the work has the primary responsibility for protection of workmen and adjacent improvements. In our opinion, the contractor will be in the best position to observe subsurface conditions continuously throughout the construction process and to respond to variable soil and groundwater conditions. Therefore, the contractor should have the primary responsibility for deciding whether or not to use open cut slopes for much of the excavations rather than some form of temporary excavation support, and for establishing the safe inclination of the cut slope. Acceptable slope inclinations for utilities and ancillary excavations should be determined during construction. Because of the diversity of construction techniques and available shoring May 4, 2016 | Page 10 File No. 0482-051-03 systems, the design of temporary shoring is most appropriately left up to the contractor proposing to complete the installation. Temporary cut slopes and shoring must comply with the provisions of Title 296 Washington Administrative Code (WAC), Part N, â€œExcavation, Trenching and Shoring.â€ Because the contractor has control of the construction operations, the contractor should be made responsible for the stability of cut slopes, as well as the safety of the excavations. The contractor should take all necessary steps to ensure the safety of the workers near the slopes. Temporary Cut Slopes For planning purposes, temporary unsupported cut slopes more than 4 feet high may be inclined at 1.5H:1V in the fill soils and native recessional outwash soils encountered at the site. These slopes may need to be flattened by the contractor if significant caving/sloughing or groundwater seepage occurs. Deeper excavations near or below the water table may require dewatering and/or shoring to maintain safe working conditions. For open cuts at the site, we recommend that: â– No traffic, construction equipment, stockpiles, or building supplies be allowed at the top of the cut slopes within a distance of at least 5 feet from the top of the cut. â– The excavation does not encroach on a 1H:1V influence line projected down from the edges of nearby or planned foundation elements. â– Exposed soil along the slope be protected from surface erosion using waterproof tarps, visqueen or flash coating with shotcrete. â– Construction activities be scheduled so that the length of time the temporary cut is left open is reduced to the extent practicable. â– Erosion control measures be implemented as appropriate such that runoff from the site is reduced to the extent practicable. â– Surface water be diverted away from the excavation. â– The general condition of the slopes be observed periodically by GeoEngineers to confirm adequate stability. Utility Trenches Trench excavation, pipe bedding, and trench backfilling should be completed using the general procedures described in the 2014 WSDOT Standard Specifications or other suitable procedures specified by the project civil engineer. The recessional outwash and fill soils encountered at the site are generally of low corrosivity based on our experience in the Puget Sound area. Utility trench backfill should consist of structural fill and should be placed in uniform horizontal lifts such that adequate compaction can be achieved throughout the lift. Each lift must be compacted prior to placing the subsequent lift. Prior to compaction, the backfill should be moisture conditioned to within 2 percent of the optimum moisture content, if necessary. The backfill should be compacted in accordance with the criteria discussed above. Figure 3 illustrates the recommended trench compaction criteria under pavement and non-structural areas. May 4, 2016 | Page 11 File No. 0482-051-03 Sedimentation and Erosion Control In our opinion, the erosion potential of the on-site soils is low to moderate. Construction activities, including stripping and grading, will expose soils to the erosion effects of wind and water. The amount and potential impacts of erosion are partly related to the time of year that construction actually occurs. Wet weather construction will increase the amount and extent of erosion and potential sedimentation. Erosion and sedimentation control measures may be implemented by using a combination of interceptor swales, straw bale barriers, silt fences and straw mulch for temporary erosion protection of exposed soils. All disturbed areas should be finish graded and seeded as soon as practicable to reduce the risk of erosion. Erosion and sedimentation control measures should be installed and maintained in accordance with the requirements of the City of Arlington. Infiltration Facilities We understand that the District is planning to design the unpaved gravel areas for stormwater infiltration at the site. We understand that the pole storage yard gravel surfacing section will be underlain by a bioretention soil mix layer for stormwater treatment. We also understand that infiltration requirements will be designed in accordance with the Washington State Department of Ecologyâ€™s 2012 SWMMWW. Since the soils have not been glacially consolidated, a pilot infiltration test (PIT) is not required in order to estimate an initial saturated hydraulic conductivity (Ksat) per Section 3.3.4 of the SWMMWW. The initial saturated hydraulic conductivity values were estimated using the grain size analysis method per Section 3.3.6 of the SWMMWW. We completed eight grain size analyses on selected samples from our explorations. The estimated long-term (factored) saturated hydraulic conductivity values for each sample is summarized in Table 5. TABLE 5. ESTIMATED LONG-TERM SATURATED HYDRAULIC CONDUCTIVITY Long-Term Rate (factored) Ksat USCS Depth D10 D60 D90 ffines Exploration Symbol (feet) (mm) (mm) (mm) (%) (cm/s) (in/hr) B-2 SP-SM 5 0.170 5.37 16.2 5.8 3.81 x 10-3 5.4 B-3 SM 2Â½ 0.040 0.61 8.6 13.2 1.62 x 10-3 2.3 B-5 SP-SM 5 0.100 3.07 25.5 8.1 1.76 x 10-3 2.5 TP-1 SP 6 0.120 0.31 0.7 3.7 4.52 x 10-3 6.4 TP-3 SP 6 0.230 1.22 13.3 2.6 5.43 x 10-3 7.7 TP-7 SP-SM 3 0.070 0.51 3.8 11.2 2.33 x 10-3 3.3 TP-8 SM 3 0.001 0.23 0.7 27.1 8.47 x 10-4 1.2 TP-8 SP 6 0.200 0.85 8.6 2.8 5.36 x 10-3 7.6 Notes: mm = millimeter; cm/s = centimeters per second; in/hr = inchers per hour May 4, 2016 | Page 12 File No. 0482-051-03 The estimated hydraulic conductivity values (Ksat) in Table 5 are the long-term infiltration rates and include correction factors. The correction factors used for site variability, test method, and degree of influent control to prevent siltation and bio-buildup are 0.33, 0.4, and 0.9, respectively. The combined correction factors result in an overall safety factor of 8.4 and were applied as outlined in Section 3.3.6 of the SWMMWW. PITs may be completed to confirm the estimated initial infiltration rates and improve the long-term correction factor. Mounding analysis may be required, depending on the planned bottom elevation of the infiltration facility and the anticipated groundwater elevation at the site. Provided the bottom of the gravel surfacing is constructed within about 1 foot of the existing site grades, mounding analysis will likely not be required since we anticipate at least 5 feet of separation between the gravel and the seasonal high ground water level. The 2012 SWMMWW requires a CEC greater than or equal to 5 milliequivalent (meq) and an organic content greater than 0.5 percent for bio-treatment of stormwater. The CEC was measured to be 14.6 meq within the topsoil (TP-1) and 3.7 meq within the outwash sands (TP-2). The organic content was measured to be 5.7 percent within the topsoil (TP-2) and 0.8 percent with the outwash sand (TP-3). Based on the results of the preliminary testing, the topsoil at the site appears to meet the requirement for bio-treatment; however, the glacial outwash soils do not. We understand that a bioretention soil mix layer will be placed below the unpaved gravel surfacing for bio-treatment of stormwater. Recommended Additional Geotechnical Services Throughout this report, recommendations are provided where we consider additional geotechnical services to be appropriate. These additional services are summarized below: â– This report specifically addresses the proposed Pole Storage Yard site. Additional explorations will be needed for future development of other portions of the property, based on the final development plans and location of structures. Additional explorations and infiltration recommendations can be provided if requested. â– GeoEngineers should be consulted as the design progresses and retained to review the project plans and specifications when complete to confirm that our design recommendations have been implemented as intended. â– During construction, GeoEngineers should observe and evaluate the suitability of subgrades, observe installation of geotextiles, observe placement and compaction of the bioretention layer, observe and test structural backfill and gravel layers, evaluate temporary and permanent slope conditions, and provide a summary letter of our construction observation services. The purposes of GeoEngineers construction phase services are to confirm that the subsurface conditions are consistent with those observed in the explorations and other reasons described in Appendix C, Report Limitations and Guidelines for Use. LIMITATIONS We have prepared this report for the exclusive use of the Snohomish County PUD No. 1 and their authorized agents for the proposed Pole Storage Yard project as part of the Arlington Property Development in Arlington, Washington. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was May 4, 2016 | Page 13 File No. 0482-051-03 prepared. The conclusions, recommendations, and opinions presented in this report are based on our professional knowledge, judgment and experience. No warranty or other conditions, express or implied, should be understood. Any electronic form, facsimile or hard copy of the original document (email, text, table and/or figure), if provided, and any attachments should be considered a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record. Please refer to Appendix C, titled â€œReport Limitations and Guidelines for Useâ€ for additional information pertaining to use of this report. REFERENCES International Code Council, 2012, International Building Code. Minard, James P. 1985. â€œGeologic Map of the Arlington West 7.5 Minute Quadrangle, Snohomish County, Washingtonâ€ Department of the Interior, U.S. Geological Survey. Miscellaneous Field Studies Map MF-1740. Seed, H.B., et al, 1985. The influence of SPT procedures in soil liquefaction resistance evaluations. U.S. Geological Survey, 2009. â€œEarthquake Hazards Program, Interpolated Probabilistic Ground Motion for the Conterminous 48 States by Latitude Longitude, 2002 Data,â€ accessed using Earthquake Ground Motion Parameters Java Program Version 5.0.9 on October 13, 2009. Washington State Department of Ecology, 2012. â€œStormwater Management Manual for Western Washington â€“ Volume III, Hydrologic Analysis and Flow Control BMPs,â€ August 2012, Publication No. 12-10-030. Washington State Department of Transportation, 2014. Standard Specifications for Road, Bridge and Municipal Construction. Youd, T.L., et al, 2001. Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils May 4, 2016 | Page 14 File No. 0482-051-03 FIGURES UV9 Olympic Pl NE Portage St Burn Rd 206Th St NE PP oo Old Burn Rd 204Th St NE rr Lois Ln t t a ouutthhPPoorrttaa 64Th Dr NE 69Th Ave NE agg SSo gg e ee C CC C r 43Rd Ave NE rreeee re k e e 71St Ave NE e k 200Th St NE 62Nd Dr NE k Cemetery Rd 199Th St NE PP Knoll Dr r r a a i ir r i 196Th Pl NE 62Nd Ave NE iee Smokey Point Blvd CCrree ee Vista Dr Crown Ridge Blvd kk 192Nd Pl NE 23Rd Ave NE 68Th Dr NE 47Th Ave NE 63Rd Ave NE 191St Pl NE 190Th Pl NE 59Th Dr NE 188Th St NE 188Th St NE 23Rd Ave NE 188Th St NE 66Th Ave NE Champions Dr Greywalls Dr Service Rd 35Th Ave NE 184Th St NE Harrow Pl Eaglefield Dr 59Th Ave NE Oxford Dr 31St Dr NE 180Th St NE 178Th Pl NE 176Th Pl NE Arlington Muni Ironwood St 174Th Pl NE Stillaguamish Hwy 19Th Ave NE 43Rd Ave NE ARLINGTON Highland View Dr 25Th Ave NE SITE Redhawk Dr 19Th Dr NE 531 79Th Ave NE 169Th Pl NE 27Th Ave NE Twin Lakes Ave 27Th Ave NE 168Th St NE 168Th St NE 79Th Ave NE 71St Dr NE Map Revised: 17 August 2012 syi Mcpherson Rd 25Th Ave NE 165Th Pl NE kk 162Nd Pl NE ee ee rr CC aa 162Nd St NE dd ee cc ll i Gissberg Twin LakesPacific Hwy uiu 51St Ave NE QQ rkrk o 19Th Ave NE F F 156Th St NE lele 156Th St NE d didi 73Rd Ave NE M 77Th Ave NE Â§Â¨Â¦ 152Nd St NE 81St Ave NE 5 18Th Dr NE45Th Rd 147Th Pl NE 23Rd Ave NE 40Th Ave NE 67Th Ave NE 145Th St NE ddaa CCrreeekk QQuilccee 143Rd Pl NE Nina Lake W a s h i n g t o n Â§Â¨Â¦405 Âµ Â§Â¨Â¦90 2,000 0 2,000 Â§Â¨Â¦5 I d a h o Â§Â¨Â¦84 Feet O r e g o n Notes: Vicinity Map 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. Proposed Pole Storage Yard can not guarantee the accuracy and content of electronic files. The master Arlington Site Development file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Arlington, Washington 3. It is unlawful to copy or reproduce all or any part thereof, whether for personal use or resale, without permission. Data Sources: ESRI Data & Maps Figure 1 Projection: NAD 1983 UTM Zone 10N Office: SEA Path: W:\Seattle\Projects\0\0482051\01\GIS\MXD\048205101_VicinityMap.mxd PROPOSED POLE YARD X X B-1 X X 3013 DEA_CON X X TP-6 SCY X : X 3012 X 137.24 DEA_CON X REDM:BDR X 3011 TP-4 134.49 TP-1 X DEA_CON X X X TP-3 TP-7 3010 134.56 DEA_CON B-5 B-3 3009 135.31 B-2 DEA_CON TP-5 TP-2 TP-8 B-6 3008 131.92 DEA_CON B-4 BOUNDARY Notes: Legend N Site Plan 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in W E B-1 Approximate boring location Proposed Pole Yard showing features discussed in an attached document. S GeoEngineers, Inc. cannot guarantee the accuracy and content of B-3 Approximate boring/groundwater monitoring well location Arlington, Washington electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. TP-1 Approximate test pit location Figure 2 Reference: Snohomish County PUD No. 1. P:\0\0482051\CAD\03\T100 Geotech\048205103_T100_F2.dwg\TAB:F2 modified on Mar 28, 2016 - 11:55am GROUND SURFACE NON-STRUCTURAL HARDSCAPE OR AREAS PAVEMENT AREAS 95 VARIES 90 95 2 FEET SCY : REDM:BDR VARIES 90 90 (SEE NOTE 1) VARIES PIPE NOT TO SCALE LEGEND: RECOMMENDED COMPACTION AS A PERCENTAGE OF 95 MAXIMUM DRY DENSITY, BY TEST METHOD ASTM D1557 (MODIFIED PROCTOR) CONCRETE OR ASPHALT PAVEMENT BASE COURSE TRENCH BACKFILL Compaction Criteria for Trench Backfill PIPE BEDDING Proposed Pole Storage Yard Arlington Site Development Arlington, Washington NOTES: 1. All backfill under building areas should be compacted to Figure 3 at least 95 percent per ASTM D1557. P:\0\0482051\CAD\03\T100 Geotech\048205103_T100_F3.dwg\TAB:F3 modified on Mar 28, 2016 - 11:55am 0 3.0 Precipitation B-3 Pressure Transducer Data B-3 Manual Water Readings B-4 Pressure Transducer Data 2.8 B-4 Manual Water Readings 2.6 5 2.4 2.2 2.0 10 1.8 1.6 1.4 15 1.2 1.0 0.8 20 0.6 Daily Precipitation (inches) 0.4 0.2 Water Level (Feet Below Ground Surface) 25 0.0 6/1/2012 8/1/2012 2/1/2013 4/1/2013 6/1/2013 8/1/2013 2/1/2014 4/1/2014 6/1/2014 8/1/2014 2/1/2015 4/1/2015 6/1/2015 8/1/2015 2/1/2016 4/1/2016 10/1/2012 12/1/2012 10/1/2013 12/1/2013 10/1/2014 12/1/2014 10/1/2015 12/1/2015 Groundwater Level Data Notes: Proposed Pole Storage Yard 1. Precipitation Data from NOAA Land Based Station Lake Stevens 0.9 NW WA US GHCND:US1WASN0074 Arlington Site Development 2. Ground surface elevation for B-3 is approximately 134 feet (NAVD88) Arlington, Washington 3. Ground surface elevation for B-4 is approximately 134.5 feet (NAVD88) Figure 4 APPENDICES APPENDIX A Field Explorations APPENDIX A FIELD EXPLORATIONS Subsurface conditions were explored across the property by drilling six borings (B-1 through B-6) and excavating eight test pits (TP-1 to TP-8). The borings were completed on June 13 and 14, 2012 to depths ranging from 26Â½ to 51Â½ feet bgs. The test pits were completed on June 15, 2012 to depths ranging from 11 to 12 feet bgs. The locations of the explorations were surveyed by David Evans & Associates after completion of the fieldwork. The locations of the explorations are shown in the Site Plan, Figure 2. Ground surface elevations shown in the exploration logs were estimated based on the existing grade contour lines shown in Figure 2. Borings The borings were completed using a tracked drill rig with continuous-flight, hollow-stem auger drilling equipment, owned and operated by Geologic Drill Explorations, Inc. of Spokane, Washington. The borings were continuously monitored by a geotechnical engineer from our firm who examined and classified the soils encountered, obtained representative soil samples, observed groundwater conditions, and prepared a detailed log of each boring. The soils encountered in the borings were sampled at 2Â½- to 5-foot vertical intervals with a 2-inch, outside-diameter, split-barrel SPT sampler. The samples were obtained by driving the sampler 18 inches into the soil with a 140-pound automatic hammer free-falling 30 inches. The number of blows required for each 6 inches of penetration was recorded. The blow count ("N-value") of the soil was calculated as the number of blows required for the final 12 inches of penetration. This resistance, or N-value, provides a measure of the relative density of granular soils and the relative consistency of cohesive soils. Where very dense soil conditions preclude driving the full 18 inches, the penetration resistance for the partial penetration was entered in the logs. The blow counts are shown in the boring logs at the respective sample depths. Soils encountered in the borings were visually classified in general accordance with the classification system described in Figure A-1. A key to the boring log symbols is also presented in Figure A-1. The logs of the borings are presented in Figures A-2 through A-7. The boring logs are based on our interpretation of the field and laboratory data and indicate the various types of soils and groundwater conditions encountered. The logs also indicate the depths at which these soils or their characteristics change; although, the change may actually be gradual. If the change occurred between samples, it was interpreted. The densities noted in the boring logs are based on the blow count data obtained in the borings and judgment based on the conditions encountered. Observations of groundwater conditions were made during drilling. Groundwater conditions observed during drilling represent a short-term condition and may or may not be representative of the long-term groundwater conditions at the site. Monitoring Wells A representative of GeoEngineers observed the installation of monitoring wells in borings B-3 and B-4. The monitoring wells were constructed using 2-inch-diameter, polyvinyl chloride (PVC) casing. The depth to which the casing was installed was selected based on our understanding of subsurface soil and groundwater conditions observed during drilling. The lower portion of the casing was slotted to allow entry May 4, 2016| Page A-1 File No. 0482-051-03 of water into the casing. Medium sand was placed in the borehole annulus surrounding the slotted portion of the casing. A bentonite seal was placed above and below (if applicable) the slotted portion of the casing. The monitoring wells were protected by installing flush-mount steel monuments set in concrete. Completion details for the monitoring wells are shown in the logs presented in Figures A-4 and A-5. Data loggers were installed within the monitoring wells to record groundwater elevations versus time. Test Pits Eight test pits (TP-1 through TP-8) were excavated using a rubber tire backhoe. The test pits were continuously observed by an engineer from our firm who classified the soils encountered, obtained representative soil samples and maintained a detailed log of each test pit. The upper 4 feet of each test pit was probed with a Â½-inch-diameter steel probe rod to estimate density. Probe depths (P) are shown in the test pit logs. In addition, pertinent information, including soil sample depths, stratigraphy, caving, and groundwater seepage were recorded. The soils encountered during excavation were visually classified in general accordance with the soil classification system described in Figure A-1. The logs of the test pits are presented in Figures A-8 through A-15. Representative soil samples were obtained from the test pits, logged, sealed in plastic bags and transported to our laboratory. The field classifications were further evaluated in our laboratory. Observations of groundwater conditions were made during excavation. Groundwater conditions encountered during excavation are presented in the test pit logs. Groundwater conditions observed during excavation represent a short-term condition and may or may not be representative of the long-term groundwater conditions at the site. May 4, 2016 | Page A-2 File No. 0482-051-03 SOIL CLASSIFICATION CHART ADDITIONAL MATERIAL SYMBOLS SYMBOLS TYPICAL SYMBOLS TYPICAL MAJOR DIVISIONS GRAPH LETTER DESCRIPTIONS GRAPH LETTER DESCRIPTIONS WELL-GRADED GRAVELS, CLEAN GW GRAVEL - SAND MIXTURES AC Asphalt Concrete GRAVEL GRAVELS AND GRAVELLY (LITTLE OR NO FINES) GP POORLY-GRADED GRAVELS, SOILS GRAVEL - SAND MIXTURES CC Cement Concrete COARSE GRAVELS WITH GM SILTY GRAVELS, GRAVEL - SAND GRAINED MORE THAN 50% - SILT MIXTURES Crushed Rock/ OF COARSE FINES CR SOILS FRACTION Quarry Spalls RETAINED ON NO. (APPRECIABLE AMOUNT CLAYEY GRAVELS, GRAVEL - 4 SIEVE OF FINES) GC SAND - CLAY MIXTURES Topsoil/ TS Forest Duff/Sod SW WELL-GRADED SANDS, CLEAN SANDS GRAVELLY SANDS MORE THAN 50% SAND Groundwater Contact RETAINED ON NO. AND (LITTLE OR NO FINES) 200 SIEVE POORLY-GRADED SANDS, SANDY SP GRAVELLY SAND Measured groundwater level in SOILS exploration, well, or piezometer MORE THAN 50% SANDS WITH SM SILTY SANDS, SAND - SILT OF COARSE MIXTURES FRACTION FINES Measured free product in well or PASSING NO. 4 piezometer SIEVE (APPRECIABLE AMOUNT SC CLAYEY SANDS, SAND - CLAY OF FINES) MIXTURES INORGANIC SILTS, ROCK Graphic Log Contact ML FLOUR, CLAYEY SILTS WITH SLIGHT PLASTICITY INORGANIC CLAYS OF LOW TO Distinct contact between soil strata SILTS MEDIUM PLASTICITY, GRAVELLY AND LIQUID LIMIT CL CLAYS, SANDY CLAYS, SILTY FINE LESS THAN 50 CLAYS, LEAN CLAYS GRAINED CLAYS Approximate contact between soil SOILS OL ORGANIC SILTS AND ORGANIC strata SILTY CLAYS OF LOW PLASTICITY INORGANIC SILTS, MICACEOUS Material Description Contact MORE THAN 50% MH PASSING NO. 200 OR DIATOMACEOUS SILTY SIEVE SOILS SILTS Contact between geologic units LIQUID LIMIT CH INORGANIC CLAYS OF HIGH AND GREATER THAN 50 PLASTICITY CLAYS Contact between soil of the same OH ORGANIC CLAYS AND SILTS OF geologic unit MEDIUM TO HIGH PLASTICITY PEAT, HUMUS, SWAMP SOILS HIGHLY ORGANIC SOILS PT WITH HIGH ORGANIC CONTENTS Laboratory / Field Tests NOTE: Multiple symbols are used to indicate borderline or dual soil classifications %F Percent fines %G Percent gravel Sampler Symbol Descriptions AL Atterberg limits CA Chemical analysis 2.4-inch I.D. split barrel CP Laboratory compaction test CS Consolidation test Standard Penetration Test (SPT) DS Direct shear Shelby tube HA Hydrometer analysis MC Moisture content Piston MD Moisture content and dry density OC Organic content Direct-Push PM Permeability or hydraulic conductivity PI Plasticity index Bulk or grab PP Pocket penetrometer PPM Parts per million Continuous Coring SA Sieve analysis TX Triaxial compression Blowcount is recorded for driven samplers as the number UC Unconfined compression of blows required to advance sampler 12 inches (or VS Vane shear distance noted). See exploration log for hammer weight and drop. Sheen Classification NS No Visible Sheen A "P" indicates sampler pushed using the weight of the SS Slight Sheen drill rig. MS Moderate Sheen HS Heavy Sheen A "WOH" indicates sampler pushed using the weight of NT Not Tested the hammer. NOTE: The reader must refer to the discussion in the report text and the logs of explorations for a proper understanding of subsurface conditions. Descriptions on the logs apply only at the specific exploration locations and at the time the explorations were made; they are not warranted to be representative of subsurface conditions at other locations or times. KEY TO EXPLORATION LOGS FIGURE A-1 Rev. 02/16 Start End Total Logged By SMJ Geologic Drill Drilling Drilled 6/13/2012 6/13/2012 Depth (ft) 26.5 Checked By BPD Driller Explorations, Inc. Method Hollow-stem Auger Surface Elevation (ft) 137 Hammer Autohammer Drilling Diedrich D-50 Track Rig Vertical Datum NAVD88 Data 140 (lbs) / 30 (in) Drop Equipment Easting (X) System Groundwater Northing (Y) Datum Depth to Date Measured Water (ft) Elevation (ft) Notes: Elevation estimated from base survey map See Remarks FIELD DATA MATERIAL REMARKS DESCRIPTION Elevation (feet)Depth (feet)IntervalRecovered (in)Blows/footCollected SampleSample NameTestingWater LevelGraphic LogGroupClassification MoistureContent (%)FinesContent (%) 0 TS 7 inches topsoil and roots Recently mowed weeds and blackberries SP-SM Light brown fine to medium sand with silt and trace gravel (loose to medium dense, moist) 135 (recessional outwash) 18 10 1 10 SP Light brown fine to medium sand with trace 5 gravel (medium dense, moist) 12 20 2 5 130 SP-SM Grayish brown fine to medium sand with silt and occasional gravel (medium dense to 12 30 3 dense, moist) 10 4 Groundwater seepage observed at 10 feet 10 21 Becomes moist to wet SP Brown fine to medium sand (medium dense, wet) 125 15 5 Driller added drilling mud at 15 feet 18 20 120 SP-SM Grayish brown fine to medium sand with silt (medium dense, wet) 20 6 12 22 115 25 7 10 22 Notes: See Figure A-1 for explanation of symbols. Elevation estimated from base survey map Log of Boring B-1 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-2 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_GEOTECH_STANDARDProject Number: 0482-051-03 Sheet 1 of 1 Start End Total Logged By SMJ Geologic Drill Drilling Drilled 6/14/2012 6/14/2012 Depth (ft) 26.5 Checked By BPD Driller Explorations, Inc. Method Hollow-stem Auger Surface Elevation (ft) 132 Hammer Autohammer Drilling Diedrich D-50 Track Rig Vertical Datum NAVD88 Data 140 (lbs) / 30 (in) Drop Equipment Easting (X) System Groundwater Northing (Y) Datum Depth to Date Measured Water (ft) Elevation (ft) Notes: Elevation estimated from base survey map See Remarks FIELD DATA MATERIAL REMARKS DESCRIPTION Elevation (feet)Depth (feet)IntervalRecovered (in)Blows/footCollected SampleSample NameTestingWater LevelGraphic LogGroupClassification MoistureContent (%)FinesContent (%) 0 TS 8 inches topsoil and roots Recently mowed weeds and blackberries SP-SM Light brown medium to coarse sand with silt and trace gravel (medium dense, moist) 130 (recessional outwash) 18 15 1 9 5 2 4 6 SA 18 26 Increased gravel content SA 125 SP-SM Grayish brown fine to medium sand with silt and gravel (meidum dense, moist to wet) 12 18 3 8 10 4 14 18 Becomes wet Groundwater seepage observed at 11 feet 120 ML/SW-SM Grayish brown silt and interbedded fine to coarse sand with gravel (medium dense, wet) 15 5 Driller added drilling mud at 15 feet 16 28 115 SM Grayish brown silty fine to medium sand with occasional gravel silt layer (medium dense, wet) 20 6 12 23 110 25 7 1 foot of heave at 25 feet 12 14 Notes: See Figure A-1 for explanation of symbols. Elevation estimated from base survey map Log of Boring B-2 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-3 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_GEOTECH_STANDARDProject Number: 0482-051-03 Sheet 1 of 1 Start End Total Logged By SMJ Geologic Drill Drilling 51.5 Driller Hollow-stem Auger Drilled 6/14/2012 6/14/2012 Depth (ft) Checked By BPD Explorations, Inc. Method Hammer Autohammer Drilling Diedrich D-50 Track Rig Data 140 (lbs) / 30 (in) Drop Equipment DOE Well I.D.: BHJ197 A 2 (in) well was installed on to a depth of 20 (ft). Surface Elevation (ft) 134 Top of Casing Vertical Datum NAVD88 Elevation (ft) Groundwater Depth to Date Measured Water (ft) Elevation (ft) Easting (X) Horizontal Northing (Y) Datum 6/25/2012 9.7 124.3 Notes: Elevation estimated from base survey map FIELD DATA WELL LOG MATERIAL Steel surface DESCRIPTION monument Elevation (feet)Depth (feet)IntervalRecovered (in)Blows/footCollected SampleSample NameTestingWater LevelGraphic LogGroupClassification MoistureContent (%)FinesContent (%) 0 TS 6 inches topsoil and roots Concrete surface SM Light brown silty fine to medium sand with 1.0 seal gravel, trace organic matter (medium dense, moist) Bentonite 16 14 1 11 13 SA 130 4.0 2-inch Schedule SP Light brown and gray fine to medium sand with 40 PVC well 5 trace gravel (loose, moist) (recessional 5.0 casing 12 14 2 outwash) 5 10-20 sand backfill SP-SM Grayish brown fine to medium sand with silt and gravel (medium dense, moist) 12 30 3 7 125 SW-SM Brown fine to coarse sand with silt and gravel 10 (medium dense, wet) 5 25 4 SP-SM Grayish brown fine to medium sand with silt 2-inch Schedule and occasional gravel (medium dense, wet) 40 PVC screen, 0.02-inch slot 120 width 15 18 29 5 Driller added drilling mud at 15 feet 115 20 19.8 End cap 9 23 6 12 6 20.0 %F Bentonite 110 25 16 25 7 SM Grayish brown silty fine to medim sand with occasional gravel (medium dense, wet) 105 30 14 25 8 ML Grayish brown silt with occasional interbedded fine to medium sand with gravel (medium dense, wet) 100 35 Notes: See Figure A-1 for explanation of symbols. Elevation estimated from base survey map Log of Boring B-3 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-4 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_GEOTECH_WELLProject Number: 0482-051-03 Sheet 1 of 2 FIELD DATA WELL LOG MATERIAL DESCRIPTION Elevation (feet)Depth (feet)IntervalRecovered (in)Blows/footCollected SampleSample NameTestingWater LevelGraphic LogGroupClassification MoistureContent (%)FinesContent (%) 35 12 27 9 Bentonite 95 40 18 32 10 Becomes dense 90 45 Becomes medium dense 18 22 11 23 6 %F 85 50 18 17 12 51.5 Notes: See Figure A-1 for explanation of symbols. Elevation estimated from base survey map Log of Boring B-3 (continued) Project: Arlington Site Development Project Location: Arlington, Washington Figure A-4 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_GEOTECH_WELLProject Number: 0482-051-03 Sheet 2 of 2 Start End Total Logged By SMJ Geologic Drill Drilling 26.5 Driller Hollow-stem Auger Drilled 6/14/2012 6/14/2012 Depth (ft) Checked By BPD Explorations, Inc. Method Hammer Autohammer Drilling Diedrich D-50 Track Rig Data 140 (lbs) / 30 (in) Drop Equipment DOE Well I.D.: BHJ196 A 2 (in) well was installed on to a depth of 20 (ft). Surface Elevation (ft) 134.5 Top of Casing Vertical Datum NAVD88 Elevation (ft) Groundwater Depth to Date Measured Water (ft) Elevation (ft) Easting (X) Horizontal Northing (Y) Datum 6/25/2012 5.7 128.8 Notes: Elevation estimated from base survey map FIELD DATA WELL LOG MATERIAL Steel surface DESCRIPTION monument Elevation (feet)Depth (feet)IntervalRecovered (in)Blows/footCollected SampleSample NameTestingWater LevelGraphic LogGroupClassification MoistureContent (%)FinesContent (%) 0 TS 9 inches topsoil and roots Concrete surface SM Light brown silty fine to medium sand with 1.0 seal gravel, trace organic matter (loose, moist) Bentonite 18 8 1 11 MC 4.0 2-inch Schedule 130 SP-SM Light brown fine to medium sand with silt and 40 PVC well 5 gravel (medium dense, moist) (recessional 5.0 casing 18 22 2 outwash) 6 MC 10-20 sand backfill 12 22 3 Becomes wet 125 SP Grayish brown fine to medium sand with gravel 10 (medium dense, wet) 18 23 4 SP-SM Grayish brown fine to medium sand with silt 2-inch Schedule and occasional gravel (medium dense, wet) 40 PVC screen, Driller added drilling mud at 13 feet 0.02-inch slot width 120 15 18 21 5 SM Grayish brown silty fine to medium sand (medium dense to dense, wet) 115 19.8 20 End cap 18 30 6 1 foot heave at 20 feet 12 20.0 MC 110 25 18 12 7 26.5 Notes: See Figure A-1 for explanation of symbols. Elevation estimated from base survey map Log of Boring B-4 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-5 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_GEOTECH_WELLProject Number: 0482-051-03 Sheet 1 of 1 Start End Total Logged By SMJ Geologic Drill Drilling Drilled 6/13/2012 6/13/2012 Depth (ft) 26.5 Checked By BPD Driller Explorations, Inc. Method Hollow-stem Auger Surface Elevation (ft) 136.5 Hammer Autohammer Drilling Diedrich D-50 Track Rig Vertical Datum NAVD88 Data 140 (lbs) / 30 (in) Drop Equipment Easting (X) System Groundwater Northing (Y) Datum Depth to Date Measured Water (ft) Elevation (ft) Notes: Elevation estimated from base survey map See Remarks FIELD DATA MATERIAL REMARKS DESCRIPTION Elevation (feet)Depth (feet)IntervalRecovered (in)Blows/footCollected SampleSample NameTestingWater LevelGraphic LogGroupClassification MoistureContent (%)FinesContent (%) 0 TS 6 inches topsoil and roots Recently mowed weeds and blackberries SP-SM Grayish brown fine to medium sand with silt, 135 trace roots (loose, moist) (recessional outwash) 14 9 1 6 MC 5 2 7 8 18 15 Becomes medium dense with gravel SA 130 12 16 3 Becomes wet Groundwater seepage observed at 8 feet 10 4 Driller added drilling mud at 10 feet 18 23 125 SW-SM Grayish brown fine to coarse sand with silt and gravel (medium dense, wet) 15 5 10 27 120 SM Grayish brown silty fine to medium sand (medium dense, wet) 20 6 12 12 115 25 7 12 22 110 Notes: See Figure A-1 for explanation of symbols. Elevation estimated from base survey map Log of Boring B-5 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-6 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_GEOTECH_STANDARDProject Number: 0482-051-03 Sheet 1 of 1 Start End Total Logged By SMJ Geologic Drill Drilling Drilled 6/13/2012 6/13/2012 Depth (ft) 26.5 Checked By BPD Driller Explorations, Inc. Method Hollow-stem Auger Surface Elevation (ft) 136.5 Hammer Autohammer Drilling Diedrich D-50 Track Rig Vertical Datum NAVD88 Data 140 (lbs) / 30 (in) Drop Equipment Easting (X) System Groundwater Northing (Y) Datum Depth to Date Measured Water (ft) Elevation (ft) Notes: Elevation estimated from base survey map See Remarks FIELD DATA MATERIAL REMARKS DESCRIPTION Elevation (feet)Depth (feet)IntervalRecovered (in)Blows/footCollected SampleSample NameTestingWater LevelGraphic LogGroupClassification MoistureContent (%)FinesContent (%) 0 TS 6 inches topsoil and roots Recently mowed weeds and blackberries SM Light brown silty fine to medium sand with 135 occasional gravel, organic matter (medium dense, moist) (recessional outwash) 12 14 1 20 SP-SM Light brown fine to medium sand with silt and 5 occasional gravel (medium dense, moist) 12 24 2 (recessional outwash) 7 130 18 30 3 Becomes medium dense to dense and wet Groundwater seepage observed at 7Â½ feet 2 inch silt lense SW-SM Grayish brown fine to coarse sand with gravel 10 4 17 30 (medium dense to dense, wet) 125 SM Grayish brown silty fine to medium sand with occasional gravel (medium dense, wet) 15 5 18 28 120 20 6 18 25 115 25 7 3 feet heave at 25 feet 18 24 SM Brown silty fine to medium sand (medium dense, wet) 110 Notes: See Figure A-1 for explanation of symbols. Elevation estimated from base survey map Log of Boring B-6 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-7 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_GEOTECH_STANDARDProject Number: 0482-051-03 Sheet 1 of 1 Date Excavated: 6/15/2012 Logged By: SMJ Equipment: Rubber Tire Backhoe Total Depth (ft) 12.0 SAMPLE MATERIAL REMARKS DESCRIPTION Elevation (feet)Depth (feet)Testing SampleSample NameTestingGraphic LogGroupClassificationEncountered Water MoistureContent, % 1 6 inches topsoil and roots Recently mowed weeds and blackberries TS Probe(P) = 6 to 8 inches SM Brown silty fine to medium sand with occasional gravel and organic CEC = 14.6 matter, oxidation staining (loose to medium dense, moist) 131 1 130 2 129 3 2 Grades to light brown 12 P = 6 inches 128 4 P = 4 inches 127 5 SP Light brown fine to medium sand (medium dense, moist) (recessional outwash) 126 6 3 9 SA (%F = 4) SA 125 7 124 8 123 9 4 SW Grayish brown fine to coarse sand with gravel and occasional cobbles (medium dense, moist) 122 10 121 11 Becomes wet 5 120 12 Slow groundwater seepage observed at 11 feet. No caving observed. Notes: See Figure A-1 for explanation of symbols. The depths on the test pit logs are based on an average of measurements across the test pit and should be considered accurate to 0.5 foot. Elevation estimated from base survey map Log of Test Pit TP-1 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-8 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_TESTPIT_1P_GEOTECProject Number: 0482-051-03 Sheet 1 of 1 Date Excavated: 6/15/2012 Logged By: SMJ Equipment: Rubber Tire Backhoe Total Depth (ft) 12.0 SAMPLE MATERIAL REMARKS DESCRIPTION Elevation (feet)Depth (feet)Testing SampleSample NameTestingGraphic LogGroupClassificationEncountered Water MoistureContent, % 1 8-inches topsoil and roots Recently mowed weeds and blackberries TS Probe(P) = 12 inches OC = 5.7% SM Brown silty fine to medium sand with occasional gravel, cobbles and 131 1 organic matter (loose, moist) 130 2 SP Light brown fine to medium sand (medium dense, moist) (recessional P = 6 inches outwash) 129 3 2 P = 4 inches 6 CEC = 3.7 128 4 P = 3 inches 127 5 126 6 3 SP Gray and brown coarse sand with gravel and occasional cobbles P = 2 inches (medium dense, moist) 125 7 124 8 SW Grayish brown fine to coarse sand with gravel (medium dense, moist) 123 9 4 Becomes wet 122 10 121 11 5 120 12 Slow groundwater seepage observed at 9 feet. Severe caving observed at 12 feet. Notes: See Figure A-1 for explanation of symbols. The depths on the test pit logs are based on an average of measurements across the test pit and should be considered accurate to 0.5 foot. Elevation estimated from base survey map Log of Test Pit TP-2 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-9 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_TESTPIT_1P_GEOTECProject Number: 0482-051-03 Sheet 1 of 1 Date Excavated: 6/15/2012 Logged By: SMJ Equipment: Rubber Tire Backhoe Total Depth (ft) 12.0 SAMPLE MATERIAL REMARKS DESCRIPTION Elevation (feet)Depth (feet)Testing SampleSample NameTestingGraphic LogGroupClassificationEncountered Water MoistureContent, % 1 6-inches topsoil and roots Recently mowed weeds and blackberries TS Probe(P) = 12 inches SM Brown silty fine to medium sand with occasional gravel (loose, moist) 133 1 132 2 SP Light brown fine to medium sand with occasional gravel (loose to P = 8 inches medium dense, moist) (recessional outwash) 131 3 2 P = 6 inches 9 OC = 0.8% 130 4 P = 4 to 5 inches 129 5 128 6 3 P = 4 inches Grades to brown with increased gravel 5 SA SA (%F = 3) 127 7 126 8 SW Gray and brown fine to coarse sand with gravel (medium dense, moist) 125 9 4 124 10 Becomes wet 123 11 5 122 12 Moderate groundwater seepage observed at 10 feet. Slight caving observed at 12 feet. Notes: See Figure A-1 for explanation of symbols. The depths on the test pit logs are based on an average of measurements across the test pit and should be considered accurate to 0.5 foot. Elevation estimated from base survey map Log of Test Pit TP-3 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-10 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_TESTPIT_1P_GEOTECProject Number: 0482-051-03 Sheet 1 of 1 Date Excavated: 6/15/2012 Logged By: SMJ Equipment: Rubber Tire Backhoe Total Depth (ft) 12.0 SAMPLE MATERIAL REMARKS DESCRIPTION Elevation (feet)Depth (feet)Testing SampleSample NameTestingGraphic LogGroupClassificationEncountered Water MoistureContent, % 1 6-inches topsoil and roots Recently mowed weeds and blackberries TS Probe(P) = 12 inches SM Reddish brown silty fine to medium sand with occasional gravel (loose, moist) 134 1 133 2 P = 8 inches 132 3 2 Light brown fine to medium sand (medium dense, moist) (recessional 5 P = 6 inches SP outwash) 131 4 P = 4 inches 130 5 129 6 3 P = 2 inches 128 7 Occasional gravel 127 8 4 126 9 125 10 SP-SM Grayish brown fine to medium sand with silt and occasional gravel (medium dense, moist) 124 11 5 Becomes wet 123 12 Slow groundwater seepage observed at 12 feet. No caving observed. Notes: See Figure A-1 for explanation of symbols. The depths on the test pit logs are based on an average of measurements across the test pit and should be considered accurate to 0.5 foot. Elevation estimated from base survey map Log of Test Pit TP-4 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-11 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_TESTPIT_1P_GEOTECProject Number: 0482-051-03 Sheet 1 of 1 Date Excavated: 6/15/2012 Logged By: SMJ Equipment: Rubber Tire Backhoe Total Depth (ft) 11.0 SAMPLE MATERIAL REMARKS DESCRIPTION Elevation (feet)Depth (feet)Testing SampleSample NameTestingGraphic LogGroupClassificationEncountered Water MoistureContent, % 1 8-inches topsoil and roots Recently mowed weeds and blackberries TS Probe(P) = 12 inches SM Reddish dark brown silty fine to medium sand with occasional gravel 133 1 and organic matter (loose, moist) 132 2 SP Light brown fine to medium sand with occasional gravel and cobbles P = 8 inches (medium dense, moist) (recessional outwash) 131 3 2 5 P = 8 inches 130 4 P = 4 inches 129 5 128 6 3 P = 2 inches 127 7 126 8 125 9 4 SP-SM Gray and brown fine to medium sand with silt and occasional gravel (medium dense, wet) 124 10 5 123 11 Moderate groundwater seepage at 9 feet. Moderate caving observed at 11 feet. Notes: See Figure A-1 for explanation of symbols. The depths on the test pit logs are based on an average of measurements across the test pit and should be considered accurate to 0.5 foot. Elevation estimated from base survey map Log of Test Pit TP-5 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-12 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_TESTPIT_1P_GEOTECProject Number: 0482-051-03 Sheet 1 of 1 Date Excavated: 6/15/2012 Logged By: SMJ Equipment: Rubber Tire Backhoe Total Depth (ft) 11.0 SAMPLE MATERIAL REMARKS DESCRIPTION Elevation (feet)Depth (feet)Testing SampleSample NameTestingGraphic LogGroupClassificationEncountered Water MoistureContent, % 1 6-inches topsoil and roots Recently mowed weeds and blackberries TS Probe(P) = 12 inches SP-SM Reddish brown silty fine to medium sand with occasional gravel and organic matter (loose, moist) 137 1 136 2 SP Light brown fine to medium sand with occasional gravel (medium dense, P = 8 inches moist) (recessional outwash) 135 3 2 6 P = 6 inches 134 4 P = 4 inches 133 5 132 6 3 P = 2 inches 131 7 130 8 129 9 4 SW Gray and brown fine to coarse sand with gravel (medium dense, wet) 128 10 GP Gray and brown fine to medium gravel with sand (medium dense, wet) 5 127 11 Slow groundwater seepage observed at 9 feet. Severe caving observed at 11 feet. Notes: See Figure A-1 for explanation of symbols. The depths on the test pit logs are based on an average of measurements across the test pit and should be considered accurate to 0.5 foot. Elevation estimated from base survey map Log of Test Pit TP-6 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-13 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_TESTPIT_1P_GEOTECProject Number: 0482-051-03 Sheet 1 of 1 Date Excavated: 6/15/2012 Logged By: SMJ Equipment: Rubber Tire Backhoe Total Depth (ft) 12.0 SAMPLE MATERIAL REMARKS DESCRIPTION Elevation (feet)Depth (feet)Testing SampleSample NameTestingGraphic LogGroupClassificationEncountered Water MoistureContent, % 1 6-inches topsoil and roots Recently mowed weeds and blackberries TS Probe(P) = 12 inches SM Reddish brown silty fine to medium sand with occasional gravel and organic matter (loose, moist) 135 1 134 2 SP-SM Light brown fine to medium sand with silt and occasional gravel (loose P = 12 inches to medium dense, moist) (recessional outwash) 133 3 2 P = 8 inches 8 SA SA (%F = 11) 132 4 P = 4 inches SP Grayish brown fine to medium sand with occasional gravel (medium dense, moist) 131 5 130 6 3 P = 2 inches 129 7 128 8 SM Gray silty fine sand (medium dense, moist) 127 9 4 Becomes wet 126 10 125 11 SP-SM Grayish brown fine to medium sand with silt and occasional gravel (medium dense, wet) 5 124 12 Slow groundwater seepage observed at 9 feet. Slight caving observed at 9 feet. Notes: See Figure A-1 for explanation of symbols. The depths on the test pit logs are based on an average of measurements across the test pit and should be considered accurate to 0.5 foot. Elevation estimated from base survey map Log of Test Pit TP-7 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-14 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_TESTPIT_1P_GEOTECProject Number: 0482-051-03 Sheet 1 of 1 Date Excavated: 6/15/2012 Logged By: SMJ Equipment: Rubber Tire Backhoe Total Depth (ft) 12.0 SAMPLE MATERIAL REMARKS DESCRIPTION Elevation (feet)Depth (feet)Testing SampleSample NameTestingGraphic LogGroupClassificationEncountered Water MoistureContent, % 1 8-inches topsoil and roots Recently mowed weeds and blackberries TS Probe(P) = 12 inches SM Reddish brown silty fine to medium sand with organic matter (loose to 135 1 medium dense, moist) P = 8 inches 134 2 P = 8 inches 133 3 2 P = 4 inches 17 SA SA (%F = 27) 132 4 131 5 SP Light brown fine to medium sand with gravel (medium dense, moist) (recessional outwash) 130 6 3 P = 2 inches 5 SA SA (%F = 3) 129 7 128 8 127 9 4 126 10 Grades to grayish brown and becomes wet SP-SM Grayish brown fine to medium sand with gravel and occasional cobbles (medium dense, wet) 125 11 5 124 12 Moderate groundwater seepage observed at 10 feet. Moderate caving observed at 10 feet. Notes: See Figure A-1 for explanation of symbols. The depths on the test pit logs are based on an average of measurements across the test pit and should be considered accurate to 0.5 foot. Elevation estimated from base survey map Log of Test Pit TP-8 Project: Arlington Site Development Project Location: Arlington, Washington Figure A-15 Seattle: Date:5/4/16 Path:P:\0\0482051\GINT\048205103.GPJ DBTemplate/LibTemplate:GEOENGINEERS8.GDT/GEI8_TESTPIT_1P_GEOTECProject Number: 0482-051-03 Sheet 1 of 1 APPENDIX B Laboratory Testing APPENDIX B LABORATORY TESTING Soil samples obtained from the explorations were transported to our laboratory and evaluated to confirm or modify field classifications, as well as to evaluate engineering and index properties of the soil samples. Representative samples were selected for laboratory testing consisting of moisture content, grain size distribution determination, percent passing U.S. No. 200 sieve, organic content, and cation exchange capacity. The tests were performed in general accordance with ASTM Standard Practices and Test Methods or other applicable procedures. Soil Classification All soil samples obtained from the explorations were visually classified in the field and/or in our laboratory using a system based on the Unified Soil Classification System (USCS) and ASTM classification methods. ASTM test method D 2488 was used to visually classify the soil samples, while ASTM D 2487 was used to classify the soils based on laboratory tests results. These classification procedures are incorporated in the exploration logs shown in Figures A-2 through A-15. Moisture Content Testing Moisture content tests were completed in general accordance with ASTM D 2216 for representative samples obtained from the explorations. The results of these tests are presented in the boring and test pit logs shown in Figures A-2 through A-15 at the depths at which the samples were obtained. Percent Passing U.S. No. 200 Sieve Selected samples were "washed" through the U.S. No. 200 mesh sieve to determine the relative percentages of coarse- and fine-grained particles in the soil. The percent passing value represents the percentage by weight of the sample finer than the U.S. No. 200 sieve. These tests were conducted to verify field descriptions and to determine the fines content for analysis purposes. The tests were conducted in general accordance with ASTM D 1140, and the results are shown in the exploration logs at the respective sample depths. Sieve Analyses Sieve analyses were performed on eight samples in general accordance with ASTM D 422 to determine the sample grain size distribution. The wet sieve analysis method was used to determine the percentage of soil greater than the U.S. No. 200 mesh sieve. The results of the sieve analyses were plotted, classified in general accordance with the USCS, and are presented in Figures B-1 and B-2. Organic Content Organic content tests were completed on two samples in general accordance with ASTM D 2974 for representative samples obtained from the explorations. The results of these tests are presented in the test pit logs shown in Figures A-9 and A-10. Cation Exchange Capacity (CEC) CEC tests were completed on two samples in general accordance with U.S. Environmental Protection Agency (EPA) Method 9081. The results of these tests are presented in the test pit logs shown in Figures A-8 and A-9. May 4, 2016 | Page B-1 File No. 0482-051-03 0482-051-01 SAS: SAS 06-26-2012 U.S. STANDARD SIEVE SIZE 3â€ 1.5â€ 3/4â€ 3/8â€ #4 #10 #20 #40 #60 #100 #200 100 90 80 70 60 50 40 30 20 PERCENT PASSING BY WEIGHT . 10 SIEVE ANALYSIS RESULTS 0 1000 100 10 1 0.1 0.01 0.001 FIGURE GRAIN SIZE IN MILLIMETERS GRAVEL SAND B BOULDERS COBBLES SILT OR CLAY -1 COARSE FINE COARSE MEDIUM FINE EXPLORATION DEPTH SYMBOL SOIL CLASSIFICATION NUMBER (ft) B-2 5 Medium to coarse sand with silt and gravel (SP-SM) B-3 2Â½ Silty fine to medium sand with gravel (SM) B-5 5 Fine to medium sand with silt and gravel (SP-SM) TP-1 6 Fine to medium sand (SP) 0482-051-01 SAS: SAS 06-26-2012 U.S. STANDARD SIEVE SIZE 3â€ 1.5â€ 3/4â€ 3/8â€ #4 #10 #20 #40 #60 #100 #200 100 90 80 70 60 50 40 30 20 PERCENT PASSING BY WEIGHT . 10 SIEVE ANALYSIS RESULTS 0 1000 100 10 1 0.1 0.01 0.001 FIGURE B GRAIN SIZE IN MILLIMETERS GRAVEL SAND BOULDERS COBBLES SILT OR CLAY -2 COARSE FINE COARSE MEDIUM FINE EXPLORATION DEPTH SYMBOL SOIL CLASSIFICATION NUMBER (ft) TP-3 6 Fine to medium sand with gravel (SP) TP-7 3 Fine to medium sand with silt and occasional gravel (SP-SM) TP-8 3 Silty fine to medium sand (SM) TP-8 6 Fine to medium sand with gravel (SP) APPENDIX C Report Limitations and Guidelines for Use APPENDIX C REPORT LIMITATIONS AND GUIDELINES FOR USE1 This appendix provides information to help you manage your risks with respect to the use of this report. Read These Provisions Closely It is important to recognize that the geoscience practices (geotechnical engineering, geology and environmental science) rely on professional judgment and opinion to a greater extent than other engineering and natural science disciplines, where more precise and/or readily observable data may exist. To help clients better understand how this difference pertains to our services, GeoEngineers includes the following explanatory â€œlimitationsâ€ provisions in its reports. Please confer with GeoEngineers if you need to know more how these â€œReport Limitations and Guidelines for Useâ€ apply to your project or site. Geotechnical Services are Performed for Specific Purposes, Persons and Projects This report has been prepared for Snohomish County PUD No. 1 and for the proposed Pole Storage Yard project as part of the Arlington property development in Arlington, Washington. The information contained herein is not applicable to other sites or projects. GeoEngineers structures its services to meet the specific needs of its clients. No party other than the party to whom this report is addressed may rely on the product of our services unless we agree to such reliance in advance and in writing. Within the limitations of the agreed scope of services for the Project, and its schedule and budget, our services have been executed in accordance with our Agreement with Snohomish County PUD No. 1 (Contract No. 80173) including Amendment 1 and generally accepted geotechnical practices in this area at the time this report was prepared. We do not authorize, and will not be responsible for, the use of this report for any purposes or projects other than those identified in the report. A Geotechnical Engineering or Geologic Report is based on a Unique Set of Project-Specific Factors This report has been prepared for the proposed Pole Storage Yard project as part of the Arlington property development in Arlington, Washington. GeoEngineers considered a number of unique, project-specific factors when establishing the scope of services for this project and report. Unless GeoEngineers specifically indicates otherwise, it is important not to rely on this report if it was: â– not prepared for you, â– not prepared for your project, â– not prepared for the specific site explored, or â– completed before important project changes were made. 1 Developed based on material provided by ASFE, Professional Firms Practicing in the Geosciences; www.asfe.org. May 4, 2016 | Page C-1 File No. 0482-051-03 For example, changes that can affect the applicability of this report include those that affect: â– the function of the proposed structure; â– elevation, configuration, location, orientation or weight of the proposed structure; â– composition of the design team; or â– project ownership. If changes occur after the date of this report, GeoEngineers cannot be responsible for any consequences of such changes in relation to this report unless we have been given the opportunity to review our interpretations and recommendations. Based on that review, we can provide written modifications or confirmation, as appropriate. Environmental Concerns are Not Covered Unless environmental services were specifically included in our scope of services, this report does not provide any environmental findings, conclusions, or recommendations, including but not limited to, the likelihood of encountering underground storage tanks or regulated contaminants. Subsurface Conditions Can Change This geotechnical or geologic report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by man-made events such as construction on or adjacent to the site, new information or technology that becomes available subsequent to the report date, or by natural events such as floods, earthquakes, slope instability or groundwater fluctuations. If more than a few months have passed since issuance of our report or work product, or if any of the described events may have occurred, please contact GeoEngineers before applying this report for its intended purpose so that we may evaluate whether changed conditions affect the continued reliability or applicability of our conclusions and recommendations. Geotechnical and Geologic Findings are Professional Opinions Our interpretations of subsurface conditions are based on field observations from widely spaced sampling locations at the site. Site exploration identifies the specific subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field and laboratory data and then applied its professional judgment to render an informed opinion about subsurface conditions at other locations. Actual subsurface conditions may differ, sometimes significantly, from the opinions presented in this report. Our report, conclusions and interpretations are not a warranty of the actual subsurface conditions. Geotechnical Engineering Report Recommendations are Not Final We have developed the following recommendations based on data gathered from subsurface investigation(s). These investigations sample just a small percentage of a site to create a snapshot of the subsurface conditions elsewhere on the site. Such sampling on its own cannot provide a complete and accurate view of subsurface conditions for the entire site. Therefore, the recommendations included in this report are preliminary and should not be considered final. GeoEngineersâ€™ recommendations can be finalized only by observing actual subsurface conditions revealed during construction. GeoEngineers May 4, 2016 | Page C-2 File No. 0482-051-03 cannot assume responsibility or liability for the recommendations in this report if we do not perform construction observation. We recommend that you allow sufficient monitoring, testing and consultation during construction by GeoEngineers to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes if the conditions revealed during the work differ from those anticipated, and to evaluate whether earthwork activities are completed in accordance with our recommendations. Retaining GeoEngineers for construction observation for this project is the most effective means of managing the risks associated with unanticipated conditions. If another party performs field observation and confirms our expectations, the other party must take full responsibility for both the observations and recommendations. Please note, however, that another party would lack our project- specific knowledge and resources. A Geotechnical Engineering or Geologic Report Could Be Subject to Misinterpretation Misinterpretation of this report by members of the design team or by contractors can result in costly problems. GeoEngineers can help reduce the risks of misinterpretation by conferring with appropriate members of the design team after submitting the report, reviewing pertinent elements of the design teamâ€™s plans and specifications, participating in pre-bid and preconstruction conferences, and providing construction observation. Do Not Redraw the Exploration Logs Geotechnical engineers and geologists prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. The logs included in a geotechnical engineering or geologic report should never be redrawn for inclusion in architectural or other design drawings. Photographic or electronic reproduction is acceptable, but separating logs from the report can create a risk of misinterpretation. Give Contractors a Complete Report and Guidance To help reduce the risk of problems associated with unanticipated subsurface conditions, GeoEngineers recommends giving contractors the complete geotechnical engineering or geologic report, including these â€œReport Limitations and Guidelines for Use.â€ When providing the report, you should preface it with a clearly written letter of transmittal that: â– advises contractors that the report was not prepared for purposes of bid development and that its accuracy is limited; and â– encourages contractors to confer with GeoEngineers and/or to conduct additional study to obtain the specific types of information they need or prefer. Contractors are Responsible for Site Safety on Their Own Construction Projects Our geotechnical recommendations are not intended to direct the contractorâ€™s procedures, methods, schedule or management of the work site. The contractor is solely responsible for job site safety and for managing construction operations to minimize risks to on-site personnel and adjacent properties. May 4, 2016 | Page C-3 File No. 0482-051-03 Biological Pollutants GeoEngineersâ€™ Scope of Work specifically excludes the investigation, detection, prevention or assessment of the presence of Biological Pollutants. Accordingly, this report does not include any interpretations, recommendations, findings or conclusions regarding the detecting, assessing, preventing or abating of Biological Pollutants, and no conclusions or inferences should be drawn regarding Biological Pollutants as they may relate to this project. The term â€œBiological Pollutantsâ€ includes, but is not limited to, molds, fungi, spores, bacteria and viruses, and/or any of their byproducts. A Client that desires these specialized services is advised to obtain them from a consultant who offers services in this specialized field. May 4, 2016 | Page C-4 File No. 0482-051-03 Have we delivered World Class Client Service? Please let us know by visiting www.geoengineers.com/feedback. Hydrogeologic Assessment Proposed Pole Yard Arlington, Washington for Snohomish County PUD No. 1 April 26, 2016 Hydrogeologic Assessment Proposed Pole Yard Arlington, Washington for Snohomish County PUD No. 1 April 26, 2016 8410 154th Avenue NE Redmond, Washington 98052 425.861.6000 Table of Contents INTRODUCTION ....................................................................................................................................................... 1 SCOPE OF SERVICES ............................................................................................................................................. 1 SITE DESCRIPTION AND LOCATION ...................................................................................................................... 2 PROPOSED LAND USE ACTIVITES ......................................................................................................................... 2 Pole and Transformer Storage .......................................................................................................................... 3 OVERVIEW OF GEOLOGIC AND HYDROGEOLOGIC CONDITIONS ......................................................................... 3 General Geology ................................................................................................................................................. 3 Hydrogeologic Conditions .................................................................................................................................. 4 Recharge ..................................................................................................................................................... 5 Surface Water Bodies ................................................................................................................................. 5 Water Supplies ............................................................................................................................................ 5 Water Quality ............................................................................................................................................... 5 HYDROGEOLOGIC SITE EVALUATION .................................................................................................................... 6 Soil Texture, Permeability, and Contaminant Attenuation Properties ............................................................ 6 Characteristics of the Unsaturated Soil ............................................................................................................ 6 Depth to Groundwater ....................................................................................................................................... 7 Aquifer Properties .............................................................................................................................................. 8 Potential Impacts to the Aquifer or Groundwater ............................................................................................ 8 Hazardous Materials ................................................................................................................................... 9 CONCLUSIONS AND RECOMMENDATIONS .......................................................................................................... 9 LIMITATIONS ......................................................................................................................................................... 10 REFERNECES ....................................................................................................................................................... 10 LIST OF FIGURES Figure 1. Vicinity Map Figure 2. Site Plan Figure 3. Water Level Data Figure 4. Well Location Map APPENDICES Appendix A. Water Well Reports Figure A-1 â€“ Albert Kluin Sr Well Figure A-2 â€“ Atonement Free Lutheran Well Figure A-3 â€“ Bud Nold Well Figure A-4 â€“ Canus Investment Corp (100 feet deep) Figure A-5 â€“ Canus Investment Corp (217 feet deep) Figure A-6 â€“ City of Arlington, Airport Well Figure A-7 â€“ Elwood R Falor Well Figure A-8 â€“ Gary Bohanon Well Appendix B. Report Limitations and Guidelines for Use April 26, 2016 | Page i File No. 0482-051-03 INTRODUCTION This report presents the results of our hydrogeologic assessment of the proposed Snohomish County Public Utility District No. 1 (Snohomish County PUD) Pole Yard project located between 172nd Street NE and 180th Street NE, east of 59th Avenue NE and west of the Burlington-Northern Santa Fe (BNSF) railroad in Arlington, Washington. The project location is shown on the Vicinity Map, Figure 1. The preliminary layout of the Proposed Pole Yard is shown relative to surrounding physical features on the Site Plan, Figure 2. We previously prepared a draft geotechnical report for the project titled, â€œGeotechnical Engineering Services, Local Office Replacement and Substation, Arlington, Washington,â€ dated May 20, 2013. Additionally, we have been monitoring groundwater levels at the site since February 2013. This report is based on our previous experience at the site and discussions with Snohomish County PUD. We understand that a portion of the site is being developed for a permanent treated-pole and transformer storage area (Pole Yard). Development of this Pole Yard will include constructing gravel laydown areas and asphalt-paved roadways. We understand that the transformer storage area will be paved and curbed, with stormwater captured and routed to an on-site oil stop valve. This hydrogeologic site assessment is provided for the evaluation of the potential groundwater impacts from the proposed Pole Yard on Snohomish PUD property (the site). The City of Arlington (City) requires that a hydrogeologic site assessment be completed for this project because it is located within the 1-year time-of-travel wellhead protection zone associated with a City of Arlington water-supply well, referred to as the Airport Well. The City requires submitting a written assessment that details the hydrogeologic characteristics and subsurface conditions and indicates the susceptibility and potential for contamination of groundwater supplies. The report will be prepared to meet the requirements of a hydrogeologic site assessment per Arlington Municipal Code, Chapter 20.93. SCOPE OF SERVICES Proposed project activities include permanent treated-pole and transformer storage facilities. Our scope of services for this task includes the following: 1. Reviewing available published and site-specific reports and other information regarding the geologic setting, hydrogeology and background water quality of the site and vicinity. 2. Reviewing available well and borehole data within 1,000 feet of the site. 3. Estimating groundwater elevations, recharge potential, flow direction and gradient. Three groundwater monitoring points are needed to estimate the direction of groundwater flow beneath the site. There are two existing groundwater monitoring wells on the site. Access to another well that is completed within the shallow recessional outwash aquifer (less than approximately 50 feet below ground surface) is needed for an accurate flow direction and gradient. 4. Completing a brief site visit to observe geologic conditions, nearby surface water features and springs. 5. Preparing an evaluation of the risk of the hazardous materials to be stored on the facility. If we find that there are potential risks or impacts to critical public aquifer storage recharge areas, we will provide April 26, 2016 | Page 1 File No. 0482-051-03 a discussion of alternatives to avoid or prevent the impacts. We will also describe and list best management practices (BMP) plans. 6. Preparing a hydrogeologic site assessment report by a qualified licensed hydrogeologist. We will submit a draft report to Snohomish County PUD for internal review and comment. After comments are discussed and incorporated, we will produce the final report for submittal to the City. The report will be based on the Cityâ€™s requirements that include descriptions of: ï‚§ Soil texture, permeability, and contaminant attenuation properties; ï‚§ Characteristics of the unsaturated top layer of soil, the vadose zone, and geologic material, including permeability and attenuation properties; ï‚§ Depth to groundwater and/or impermeable soil layer; ï‚§ Aquifer properties such as hydraulic conductivity and gradients; and ï‚§ Potential impacts to the aquifer or groundwater. We received information from Snohomish PUD on the substances used to treat power poles, a preliminary design plan for the Pole Yard, and general descriptions of the proposed facility uses and on-site handling or storage of hazardous materials. Other sources of information are listed in the Bibliography at the end of this report. SITE DESCRIPTION AND LOCATION The site is located approximately 2.8 miles south of the Stillaguamish River within the city limits of Arlington, Washington. Topographically, the site is located within the Marysville Trough, which is a north-south trending lowland that extends from the Stillaguamish River to approximately one mile south of the City of Marysville. The 25.6-acre site is relatively flat, and is currently undeveloped other than a temporary pole storage yard at the western edge of the property. The site grade ranges from about Elevation 140 feet1 in the northeast corner to Elevation 131 feet in the southwest corner. Vegetation on the site consists of recently mowed blackberry brambles, shrubs and scattered deciduous and conifer trees. An abandoned barn is located near the center of the property. The locations of adjacent roads and railroad, the proposed Pole Yard, and locations of boreholes and test pits related to our 2013 geotechnical study are shown on the Site Plan, Figure 2. PROPOSED LAND USE ACTIVITES A Pole Yard operated by Snohomish PUD is proposed for the site. Our understanding of the site activities are based on information provided by Ben Davis, PE of Snohomish PUD. The following activities are proposed: â– Treated power-pole storage 1 Note that all elevations provided in the report are relative to the North American Vertical Datum 1988 (NAVD88). April 26, 2016 | Page 2 File No. 0482-051-03 â– Power transformer storage â– Paved access roads â– Vehicle storage The transformer storage area will be paved and curbed in order to capture and convey stormwater to a treatment area. Within the pole storage area, the existing topsoil will be removed and a layer of soil, specially designed to absorb chemicals that may leach from the treated poles, will be installed. No fueling, fuel storage or vehicle maintenance is proposed at the site. Pole and Transformer Storage Power poles stored at Pole Yard may contain either copper-naphthenate (Cu-Nap), for poles used by Snohomish PUD after 2002, or pentachlorophenol (Penta), for poles used by Snohomish PUD before 2002. Cu-Nap-treated poles will be stored uncovered on-site for short periods of time before they are installed. Penta-treated poles will be temporarily stored uncovered after they have been decommissioned. Approximately four to six times per year, Snohomish PUD operations crews load a 10-yard dump truck with decommissioned poles and haul them off site for disposal. The majority of these poles have been treated with Penta. Rarely, creosote-treated poles are also decommissioned. The Snohomish PUD operations crews may cut Cu-Nap-treated and/or Penta-treated poles on site with a chainsaw in order to fit them into a 10- yard dump truck for disposal. No chipping or treating of poles will occur on Snohomish PUD property. New and decommissioned transformers are to be stored on site within the Pole Yard. New transformers delivered to the site are to be filled off site with mineral oil. There will be no oil-transfer activities on site. Mineral-oil-filled transformers that have been decommissioned and not visibly leaking may be temporarily stored on site. Any decommissioned transformers that are visibly leaking are double-bagged and taken to an off-site disposal facility. No older decommissioned transformers that have the potential to contain polychlorinated biphenyls (PCBs) will be transported to the site. Some vehicles may be stored uncovered elsewhere within the site that may contain potential contaminants, such as oil, diesel, gas and hydraulic fluid. The maintenance of vehicles will be done off site. Visibly leaking vehicles will be removed from the site for service at an off-site location. OVERVIEW OF GEOLOGIC AND HYDROGEOLOGIC CONDITIONS Geologic and hydrogeologic conditions in the vicinity of the site were evaluated by reviewing available published information and the site-specific geotechnical report by GeoEngineers, Inc. (GeoEngineers 2013). The following sections present a general overview of the geologic and hydrogeologic conditions in the site vicinity. General Geology The site is underlain by glacial deposits that were laid down by continental glaciers that advanced into Snohomish County several times during the Pleistocene Epoch (between 2 million and 10,000 years ago). The most recent glaciation period, the Vashon Stade, ended approximately 13,000 years ago. The Vashon Glacier covered the Puget Sound Basin before halting and retreating. After the glaciation period, the Stillaguamish River cut through the glacial deposits and deposited alluvium. The geologic units present in April 26, 2016 | Page 3 File No. 0482-051-03 the project vicinity are, from youngest to oldest: River Alluvium (Qal), Vashon Recessional Outwash (Qvr), Vashon Till (Qvt), Vashon Advance Outwash (Qva), Transitional Beds (Qtb), and Older Gravel (Qog). The following unit descriptions are from Thomas et al. (1997): â– The Qal unit is composed of fluvial deposits from the Stillaguamish River deposited after the glaciation period. Alluvium consists primarily of sand with some gravel, with lenses of fine-grained overbank deposits, gravel and cobbles. The alluvium is typically 40 feet thick near the river. â– The Qvr unit was deposited by the retreating glacier, and covers most of the Marysville Trough. The Qvr is composed of moderately to well-sorted gravel and sand that grades to silt and is typically 40 to 250 feet thick. â– The Qvt unit underlies the Qvr and was deposited by the advancing glacier overriding and reworking older deposits and rocks. Glacial till is compact and typically consists of an unsorted combination of clay- through cobble-sized sediments. The average thickness of Qvt is about 70 feet, but can range from 0 to 250 feet thick. â– The Qva unit underlies the Qvt. The Qva was deposited by meltwater originating from the advancing glacier. The Qva typically has fine-grained sediments that grade upward into coarse-grained deposits. The advance outwash is typically 120 feet thick and up to 350 feet thick. â– The Qtb underlies the Qva. The Qtb is an interglacial unit that was deposited in a low energy environment, consisting of fine-grained materials of sandy to silty clay, with lenses of sand and gravel. The Qtb unit is typically 100 feet thick, up to 400 feet thick. â– The Qog unit underlies the Qtb and is comprised of a wide range of generally coarse-grained sands and gravels. The typical thickness of Qog is about 500 feet, but it can be as thick as 1,000 feet. Hydrogeologic Conditions There are four aquifers in the project vicinity: the Alluvial Aquifer, the Vashon Recessional Aquifer, the Vashon Advance Aquifer and the Deep Aquifer. The Alluvial Aquifer is shallow and is in direct contact with the Stillaguamish River (Pacific Groundwater Group 2007a). The Alluvial Aquifer extends nearly 2 miles south of the present-day location of the Stillaguamish River, but is not present within Â¼-mile of the project site, according to mapping by Minard (1985). The Vashon Recessional Aquifer is an unconfined aquifer that occurs throughout most of the Marysville Trough, including beneath the site. The Vashon Recessional and Vashon Advance Aquifers are hydraulically connected. The transmissivity in the Vashon Recessional Aquifer in the Marysville Trough has a median estimated transmissivity of 15,000 gallons per day per foot (gpd/ft), which may be larger than expected because of a hydraulic connection with the Qva aquifer (Pacific Groundwater Group 2007a). The typical thickness of the Vashon Recessional Aquifer is about 40 feet (Thomas et al. 1997). Water levels in the Vashon Recessional Aquifer vary seasonally and annually between 4 and 19 feet below ground surface (bgs) at the site, based on data recorded during 2013 (GeoEngineers 2013) and subsequently. The Vashon Advance Aquifer is confined or unconfined depending on the presence of Qvt, which acts as a confining unit. In the Marysville Trough, the Qvt is generally eroded, effectively allowing the Qva and Qvr to be hydraulically connected (Pacific Groundwater Group 2007a). In some areas, however, Qvt can be April 26, 2016 | Page 4 File No. 0482-051-03 between 70 and 250 feet thick (Thomas et al. 1997) and can act as a confining unit between the Vashon Recessional and Vashon Advance Aquifers. The Deep Aquifer is confined by the Qtb and has a top elevation from about 100 feet to below â€“400 feet. The median value of transmissivity for the Deep Aquifer is 3,300 gpd/ft (Pacific Groundwater Group 2007a). In the vicinity of the site, the top of the Deep Aquifer is 100 feet bgs, and water levels are at about 102 feet bgs. Recharge Recharge to the aquifers is primarily by infiltration and percolation of precipitation. Average annual recharge to the groundwater by infiltration and percolation is estimated to be approximately 24 inches per year in the vicinity of the City of Arlington (Thomas et al. 1997). According to the same source, the average minimum permeability is 1.3 inches per hour for outwash deposits. The recharge potential for the proposed Pole Yard is high based on the relatively permeable surface and subsurface soils (Thomas et al. 1997). Surface Water Bodies Slightly more than Â¼ mile south of the site is an ephemeral drainage to the Middle Fork Quilceda Creek, which is not a salmon-bearing stream within the nearby reach (DNR 2016). Water Supplies The City of Arlingtonâ€™s water supply is obtained from the Haller Wellfield, the Airport Well, and an intertie between Snohomish PUD and the City of Everett (City of Arlington 2016). The Haller Wellfield is located adjacent to the Stillaguamish River, approximately 3 miles north of the Pole Yard site. The Airport Well is located approximately Â½ mile northwest of the project site. The source of the Airport Well is the Deep Aquifer (Pacific Groundwater Group 2007a). Other water-supply wells exist within the site vicinity; according to Ecology records, there are seven water-supply wells within Â¼ mile of the site boundary. No springs were identified within Â¼ mile from the site. The monitoring wells installed on site by GeoEngineers in 2012 are completed within the Vashon Recessional Aquifer. Water Quality A USGS study conducted in 1992-1993 (Thomas et al. 1997) found the groundwater quality in Snohomish County to be generally good. Water quality was observed to be soft or moderately hard, and dissolved solids concentrations ranged between 36 to 1,040 milligrams per liter (mg/L) with a median of 133 mg/L. The groundwater system had no widespread groundwater contamination, although some contamination was possible because of the presence of agriculture and septic systems. High natural concentrations of iron and manganese, two secondary (aesthetic) contaminants, were common. High iron and manganese have been detected in some water systems near the site, including the Cityâ€™s Arlington Well (Washington Department of Health database 2016). Near Arlington, detectable arsenic was found with concentrations that ranged from less than 1 to 280 micrograms per liter (Âµg/L) and a median of 2 Âµg/L. April 26, 2016 | Page 5 File No. 0482-051-03 HYDROGEOLOGIC SITE EVALUATION The following summary of findings is provided to address the City of Arlingtonâ€™s hydrogeologic site evaluation requirements as listed in Arlington Municipal Code (AMC), Chapter 20.93, Part IX Aquifer Recharge Areas (AMC 20.93.930). A portion of the subject site is located within the 1-year time-of-travel zone of the Airport Well (Pacific Groundwater Group 2007b). Although the Wellhead Protection and Watershed Control Program (RH2 2016) recommends the evaluation of restricting land uses with the 1-year time-of-travel zone through a wellhead protection ordinance, no ordinance currently exists. Soil Texture, Permeability, and Contaminant Attenuation Properties On-site subsurface explorations consisted of six borings (B-1 through B-6) and eight test pits (TP-1 through TP-8) conducted by GeoEngineers (2013). The borings were drilled in 2012 to depths of 26Â½ to 51Â½ feet bgs and the test pits were excavated to depths ranging from 11 to 12 feet below the existing site grade. The approximate locations of the explorations are shown on the Site Plan, Figure 2. Based on the explorations completed at the site, the subsurface conditions generally consist of a thin layer of silty sand overlying recessional outwash (Qvr) deposits. At the surface, we observed 4 to 8 inches of topsoil with roots overlying either fill or native recessional outwash deposits. The topsoil thickness was measured to be 4 inches at four locations and 8 inches in one location across the proposed Pole Yard. A 2-foot thick layer of disturbed native soils was observed in test pits TP-2 through TP-8. A 4-foot-thick layer of disturbed native soils or fill was observed in Boring B-4. The fill or disturbed native soils consist of loose silty sand, with occasional gravel. The fill/disturbed native soils overlie native glacially deposited recessional outwash (Marysville Sand Member) consisting of medium dense to dense sand, with variable silt and gravel content. Recessional outwash soils (Qvr) were observed to the full depth explored. The permeability of the recessional outwash in Snohomish County is conservatively estimated to be 1.3 inches per hour (Thomas et al. 1997). The moderate to high permeability of the soil increases the susceptibility of the underlying aquifer to contamination from the ground surface. However, the concentration of contaminants reaching the water table may be reduced by attenuation processes occurring within the vadose zone. Attenuation processes include biodegradation, dispersion, dilution and sorption and chemical and biological stabilization (EPA 1998). Because the water table in the recessional outwash aquifer is relatively shallow, attenuation of contaminants has a relatively short distance in which to occur before they reach the water table. Biodegradation is the most important attenuation mechanism (EPA 1998), with the organic-material content of the soil affecting contaminant attenuation and transport. The upper layer of the natural soils will be removed from the Pole Yard and replaced by soils specially selected for their attenuation properties beneath permeable areas. The treatment layer will comply with the current (2012) Ecology Stormwater Manual for Western Washington for enhanced treatment. Characteristics of the Unsaturated Soil The surface unsaturated soil is mapped as recessional outwash, which is medium dense to dense sand with variable silt and gravel. A 2- to 4-foot-thick layer of disturbed native soils or fill that consists of loose silty sand with occasional gravel was encountered overlying the recessional outwash. Beneath the surface April 26, 2016 | Page 6 File No. 0482-051-03 layer, at least between 7Â½ and 12 feet of unsaturated recessional outwash was encountered in 2012 (GeoEngineers 2012). The thickness of the unsaturated zone varies with fluctuating groundwater levels, as discussed below. The depth to the bottom of the aquifer was not clearly defined by previous explorations on site. Depth to Groundwater In 2012, groundwater was observed to range from 7 to 12 feet bgs (Elevation 121 to 129 feet). Based on water level data between 2013 and 2016 at the two monitoring wells installed on site in the shallow Vashon Recessional Aquifer, the water levels fluctuate seasonally up to 14 feet and depths range from 4 to 19 feet bgs (Elevation 115 to 131 feet) (Water Level Data, Figure 3). Our review of Washington State Department of Ecology (Ecology) Water Well Reports available on their Well Log Viewer website indicates that there are several records of water-supply wells located within Â¼ mile of the site. Locations of the wells provided on the logs are typically to the nearest quarter-quarter section and are generally considered approximate. According to Ecology records summarized in Table 1 below, there are eight water-supply wells that potentially could be located within a Â¼ mile of the property (Well Location Map, Figure 4). These wells are reportedly drilled to depths ranging from 38 to 217 feet bgs, with water levels ranging from 12 to 217 feet below the top of wells. TABLE 1. SUMMARY OF WATER-SUPPLY WELLS WITHIN THE SITE VICINITY Well Well Water State Plane Coordinates Completion Well Owner Depth Diameter Level Date (feet, bgs) (inches) (feet, bgs) Easting Northing Albert Kluin Sr 38 36 - 05/26/1952 1239205 1032849 Atonement Free 40 6 12 10/12/1987 1240489 1032802 Lutheran Bud Nold 40 6 - 06/21/1989 1240524 1034132 Canus Investment Corp. 217 6 217 10/04/1980 1240563 1035461 Canus Investment Corp. 100 6 12 08/15/1980 1240563 1035461 City of Arlington1 185 10 102 08/1945 1236680 1035611 Elwood R Falor 46 6 - 09/14/1957 1239262 1035509 Gary Bohanon 40 6 - 12/06/1989 1240489 1032802 1 According to the Wellhead Protection Memorandum (Pacific Groundwater Group 2007b), the City of Arlingtonâ€™s Airport Well is located approximately 2,100 feet from the border of the Snohomish PUD site. In addition to these eight water wells, 126 resource protection wells and dewatering wells that range from 12 to 217 feet deep are listed by Ecology within Â¼ mile of the Pole Yard site. The dewatering wells and most of the resource protection wells have likely been decommissioned based on Ecology well log records. Most of the resource protection wells are associated with Welco Lumber. The only known active water supply wells are owned by the Arlington Water Department (Group A), referred to in this report as the Airport April 26, 2016 | Page 7 File No. 0482-051-03 Well, and the Atonement Free Lutheran Church (Group B). Most of these wells do not have accurate locations beyond the typical quarter-quarter section. The Water Well Reports for these wells indicate that groundwater within the Vashon Recessional Aquifer is approximately 10 feet below ground surface. Copies of Water Well Reports for these wells are included in Appendix A. Aquifer Properties Pacific Groundwater Group (2007b) conducted a capture zone study in the vicinity of the City of Arlington, and characterized the three aquifers that are the source of the Cityâ€™s water supply: the Alluvial Aquifer, the Vashon Advance Aquifer, and the Deep Aquifer. The values for primary aquifer parameters determined from their study are presented in Table 2 below. The flow direction for the Deep Aquifer near the site is to the northwest towards the Stillaguamish River. The unconfined Vashon Recessional Aquifer beneath the site likely has a similar flow direction as the Deep Aquifer. TABLE 2. AQUIFER PARAMETERS Hydraulic Conductivity Hydraulic Gradient Effective Porosity Name K i ne (feet per day) (feet per foot) (ftÂ³/ftÂ³) Alluvial Aquifer 3,119 0.002 0.27 Vashon Recessional 180 0.011 0.27 Aquifer Vashon Advance Aquifer 40 0.016 0.27 Deep Aquifer 134 0.05 0.27 Notes: Data from Pacific Groundwater Group (2007b) We were not able to access a third well completed in the shallow Vashon Recessional Aquifer. Therefore, a site-specific hydraulic gradient and flow direction were not obtained. However, the on-site monitoring wells B-3 and B-4 are approximately 935 feet apart and the water elevation from B-3 was 5.2 feet lower than the water elevation in B-4 on February 9, 2016, consistent with a northwest flowing aquifer. The water levels in the two wells indicate a two-dimensional gradient of 0.005 feet per foot. Based on this estimated gradient and depth to groundwater measurements, we anticipate that groundwater levels below the proposed Pole Yard will be greater than 5 feet below existing grade. Potential Impacts to the Aquifer or Groundwater Because of the high permeability of the recessional outwash and the shallow depth to groundwater, the site is susceptible to shallow groundwater contamination. The source aquifer for the Airport Well is the Deep Aquifer encountered at a depth of 112 feet bgs. In order for contamination to reach the Deep Aquifer it would have to travel down through the unconfined shallow Vashon Recessional Aquifer and through a confining layer that is 9-foot-thick and consists of fine sand and clay at the well location. The confining unit therefore provides protection from contaminants potentially released at the surface. April 26, 2016 | Page 8 File No. 0482-051-03 Hazardous Materials Snohomish PUD no longer uses Penta- or creosote-treated wood poles. These products are being phased out of use as old poles are replaced with newer ones. The use of Penta and creosote to treat and preserve wood poles has been replaced by Cu-Nap. Cu-Nap is a non-restricted oil-borne wood preservative used to protect wood from decay by microorganisms and wood-eating insects. Cu-Nap concentrate is classified as a â€œgeneral useâ€ pesticide by the United States Environmental Protection Agency (EPA) under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). It has been standardized for use by the American Wood Protection Association (AWPA) (EPA Reg. No. 71992-1-54471). General use pesticides are those that are not classified by EPA for restricted use (40 CFR 152.175). The FIFRA requires that all pesticides sold or distributed in the United States be registered by the EPA. Registration is based on evaluation of scientific data and assessment of risks and benefits of a product's use. Cu-Nap-treated poles will be stored at the site according to all applicable regulations. There will be no storage or application of concentrated Cu-Nap or Penta or PCBs at the site (personal communication Ben Davis, Snohomish PUD, March 15, 2016). Equipment (vehicles or transformers) will be inspected for leaks prior to being stored at the site. Any leaking equipment will be assessed and taken to an off-site facility. CONCLUSIONS AND RECOMMENDATIONS The water-table aquifer beneath the site is shallow and is potentially susceptible to water quality impacts due to the highly permeable nature of the surface soils. However, the deeper regional aquifer that is a source for the City of Arlingtonâ€™s Airport Well, located more than 2,000 feet from the site, is likely protected by the presence of one or more fine-grained layers that form aquitards, or confining units, beneath the site, and would limit or delay contamination from reaching the deep aquifer. Furthermore, steps are planned at the site that will reduce the likelihood of the potential contaminants such as hydrocarbons, mineral oil and Cu-Nap from reaching the groundwater table. Because of the activities proposed on the site and its location within the 1-year time-of-travel wellhead protection zone of the Cityâ€™s Airport Well, we recommend the following: 1. Incorporate Best Management Practices (BMPs) that conform to Ecologyâ€™s Stormwater Management Manual for Western Washington. 2. Infiltration facilities, if proposed, should meet BMPs to protect groundwater quality. 3. Store the transformers only in a paved area designated for that purpose. 4. Capture and convey stormwater that occurs within the transformer storage area to an on-site treatment area. 5. Add a layer of soil beneath permeable sections that has improved contaminant attenuation properties. 6. Require that an approved Spill Prevention and Control Plan be prepared before the facility is actively used that identifies equipment and structures that could fail, resulting in an impact to the underlying aquifer. Spill plans shall include provisions for regular inspection, repair, and replacement of structures and equipment with the potential to fail. April 26, 2016 | Page 9 File No. 0482-051-03 In our opinion, the proposed development will likely cause little or no adverse impact to the quality of water in the shallow aquifer beneath the site if the above-mentioned recommendations are implemented, including infiltration of stormwater with sufficient treatment BMPs for the transformer storage area. The occurrence of 9 feet of unsaturated soil and a confining layer beneath the shallow aquifer will provide added protection against impacts to the deep aquifer that is the source of the City of Arlingtonâ€™s water supply. LIMITATIONS We have prepared this report for use by Snohomish County PUD No. 1 for the proposed Local Office Replacement and Substation located between 172nd Street NE and 180th Street NE off of 59th Avenue NE in Arlington, Washington. Our services were provided to complete a hydrogeologic assessment related to permitting for planned facilities and activities to be located on the property. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of hydrogeology in this area at the time this report was prepared. No warranty or other conditions, express or implied, should be understood. Please refer to Appendix B titled â€œReport Limitations and Guidelines for Useâ€ for additional information pertaining to use of this report. REFERNECES City of Arlington, 2016, 2015 Comprehensive Water System Plan. Final. Released January 2016. Prepared with assistance from RH2 Engineering Inc. and FCS Group Inc. GeoEngineers, Inc., May 20, 2013, Geotechnical Engineering Services, Local Office Replacement and Substation, Arlington, Washington. Prepared for Snohomish County PUD No. 1. File No. 0482-051-01. Snohomish County Planning and Development Services, GIS-Cartography Section. 2007. Aquifer Recharge/Wellhead Protection Map. Revised October 1, 2007. Available at http://snohomishcountywa.gov/DocumentCenter/View/8240 Thomas, B.E., Wilkinson, J.M., and Embrey, S.S. 1997. The Ground-Water System and Ground-Water Quality in Western Snohomish County, Washington. US Geological Survey Water-Resources Investigations Report 86-4312. Washington State Department of Natural Resources (DNR). 2016. Forest Practices Application Mapping Tool. Accessed on 30 March 2016. Available at https://fortress.wa.gov/dnr/protectiongis/fpamt/index.html# Minard, J.P., 1985, Geologic Maps of the Arlington West 7.5 Minute Quadrangle, Snohomish County, Washington. United States Geological Survey. Miscellaneous Field Studies Map MP-1740. Available at http://ngmdb.usgs.gov/Prodesc/proddesc_7432.htm Pacific Groundwater Group, January 2007a, Hydrogeologic Conceptual Model Summary Report. City of Arlington. April 26, 2016 | Page 10 File No. 0482-051-03 Pacific Groundwater Group. February 4, 2007b, Wellhead Protection Capture Zone Delineation Memorandum. City of Arlington. Snohomish County Planning and Development Services, GIS-Cartography Section, 2007, Aquifer Recharge/Wellhead Protection Map. Revised October 1, 2007. Available at http://snohomishcountywa.gov/DocumentCenter/View/8240 Thomas, B.E., Wilkinson, J.M., and Embrey, S.S., 1997, The Ground-Water System and Ground-Water Quality in Western Snohomish County, Washington. US Geological Survey Water-Resources Investigations Report 86-4312. U.S. Environmental Protection Agency, 1998, Technical Protocol for Evaluation Natural Attenuation of Chlorinated Solvents in Ground Water (Appendix A), U.S. EPA, Office of Research and Development, EPA./600/R-98/128. Washington State Department of Health, 2016, Sentry Internet. Division of Environmental Health, Office of Drinking Water. Available at https://fortress.wa.gov/doh/eh/portal/odw/si/Intro.aspx April 26, 2016 | Page 11 File No. 0482-051-03 FIGURES UV9 Olympic Pl NE Portage St Burn Rd 206Th St NE PP oo Old Burn Rd 204Th St NE rr Lois Ln t t a ouutthhPPoorrttaa 64Th Dr NE 69Th Ave NE agg SSo gg e ee C CC C r 43Rd Ave NE rreeee re k e e 71St Ave NE e k 200Th St NE 62Nd Dr NE k Cemetery Rd 199Th St NE PP Knoll Dr r r a a i ir r i 196Th Pl NE 62Nd Ave NE iee Smokey Point Blvd CCrree ee Vista Dr Crown Ridge Blvd kk 192Nd Pl NE 23Rd Ave NE 68Th Dr NE 47Th Ave NE 63Rd Ave NE 191St Pl NE 190Th Pl NE 59Th Dr NE 188Th St NE 188Th St NE 23Rd Ave NE 188Th St NE 66Th Ave NE Champions Dr Greywalls Dr Service Rd 35Th Ave NE 184Th St NE Harrow Pl Eaglefield Dr 59Th Ave NE Oxford Dr 31St Dr NE 180Th St NE 178Th Pl NE 176Th Pl NE Arlington Muni Ironwood St 174Th Pl NE Stillaguamish Hwy 43Rd Ave NE Highland View Dr 19Th Ave NE 25Th Ave NE SITE Redhawk Dr 19Th Dr NE 531 79Th Ave NE 169Th Pl NE 27Th Ave NE Twin Lakes Ave 27Th Ave NE 168Th St NE 168Th St NE 79Th Ave NE 71St Dr NE Map Revised: 17 August 2012 syi Mcpherson Rd 25Th Ave NE 165Th Pl NE kk 162Nd Pl NE ee ee rr CC aa 162Nd St NE dd ee cc ll i Gissberg Twin LakesPacific Hwy uiu 51St Ave NE QQ rkrk o 19Th Ave NE F F 156Th St NE lele 156Th St NE d didi 73Rd Ave NE M 77Th Ave NE Â§Â¨Â¦ 152Nd St NE 81St Ave NE 5 18Th Dr NE45Th Rd 147Th Pl NE 23Rd Ave NE 40Th Ave NE 67Th Ave NE 145Th St NE ddaa CCrreeekk QQuilccee 143Rd Pl NE Nina Lake W a s h i n g t o n Â§Â¨Â¦405 Âµ Â§Â¨Â¦90 2,000 0 2,000 Â§Â¨Â¦5 I d a h o Â§Â¨Â¦84 Feet O r e g o n Notes: Vicinity Map 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. can not guarantee the accuracy and content of electronic files. The master Proposed Pole Yard file is stored by GeoEngineers, Inc. and will serve as the official record of Arlington, Washington this communication. 3. It is unlawful to copy or reproduce all or any part thereof, whether for personal use or resale, without permission. Data Sources: ESRI Data & Maps Figure 1 Projection: NAD 1983 UTM Zone 10N Office: SEA Path: W:\Seattle\Projects\0\0482051\01\GIS\MXD\048205101_VicinityMap.mxd PROPOSED POLE YARD X X 136 B-1 137 137 X 135 X 142 3013 DEA_CON 135 10428 10427136.19 136.11TOE X TOE 10426 136.05 TOE137 10429 136.21 TOE 10425 136.14 X TOE 10430 136.18 TP-6 TOE 136 SCY X 140 : X 138 3012 X 137.24 DEA_CON X REDM:BDR X 133 136 3011 TP-4 134.49 X DEA_CON 132 133 133 134 TP-1 135 133 X X X 135 TP-3 TP-7 3010 134.56 132 DEA_CON B-5 136 135 135 B-3 136 136 3009 135.31 B-2 DEA_CON 132 TP-5 TP-2 TP-8 B-6 131 3008 131.92 132 DEA_CON 133 132 132 131 133 B-4 SITE BOUNDARY Notes: Legend N Site Plan 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in W E B-1 Approximate boring location showing features discussed in an attached document. Proposed Pole Yard GeoEngineers, Inc. cannot guarantee the accuracy and content S Arlington, Washington B-3 Approximate boring/groundwater monitoring well location 200 0 200 of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. TP-1 Approximate test pit location Feet Figure 2 Reference: Snohomish County PUD No. 1. P:\0\0482051\CAD\03\T100 Geotech\048205103_T100_F2.dwg\TAB:F2 modified on Mar 28, 2016 - 11:55am 0 3.0 Precipitation B-3 Pressure Transducer Data B-3 Manual Water Readings B-4 Pressure Transducer Data 2.8 B-4 Manual Water Readings 2.6 5 2.4 2.2 2.0 10 1.8 1.6 1.4 15 1.2 1.0 0.8 20 0.6 0.4 0.2 Daily Precipitation (inches) 25 0.0 Water Level (Feet Below Ground Surface) 6/1/2012 8/1/2012 2/1/2013 4/1/2013 6/1/2013 8/1/2013 2/1/2014 4/1/2014 6/1/2014 8/1/2014 2/1/2015 4/1/2015 6/1/2015 8/1/2015 2/1/2016 4/1/2016 10/1/2012 12/1/2012 10/1/2013 12/1/2013 10/1/2014 12/1/2014 10/1/2015 12/1/2015 Water Level Data Notes: 1. Precipitation Data from NOAA Land Based Station Lake Stevens 0.9 Proposed Pole Yard NW WA US GHCND:US1WASN0074 2. Ground surface elevation for B-3 is approximately 134 feet (NAVD88) Arlington, Washington 3. Ground surface elevation for B-4 is approximately 134.5 feet (NAVD88) Figure 3 59th Ave NE CITY OF 67th Ave NE ARLINGTON ELWOOD CANUS R FALOR ï‚¡@< INVESTMENT ï‚¡@< CORP.ï‚¡@< BUD NOLD ï‚¡@< ATONEMENT ALBERT FREE 59th Ave NE KLUIN SR LUTHERAN ï‚¡@< GARY BOHANONï‚¡@< SR 531 SR 531 172nd St NE SR 531 NE MiddleFork Quilceda Creek 67th Ave NE Legend Site Boundary 1,000 0 1,000 0.25 mile Buffer Tax Parcel Boundary Feet Âµ Notes: 1. The locations of all features shown are approximate. Well Locations are approximate and may only be accurate to Well Location Map a quarter-quarter section. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the Proposed Pole Yard accuracy and content of electronic files. The master file Arlington, Washington is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Data Source: Figure 4 Projection: NAD 1983 StatePlane Washington North FIPS 4601 Feet P:\0\0482051\GIS\MXD\048205101_WellLocations.mxd Date Exported: 04/26/16 by maugust APPENDICES APPENDIX A Water Well Reports APPENDIX B Report Limitations and Guidelines for Use APPENDIX B REPORT LIMITATIONS AND GUIDELINES FOR USE2 This appendix provides information to help you manage your risks with respect to the use of this report. Hydrogeologic Services are Performed for Specific Purposes, Persons and Projects This report has been prepared for the exclusive use of Snohomish County Public Utilities District No. 1. This report is not intended for use by others, and the information contained herein is not applicable to other sites. GeoEngineers structures our services to meet the specific needs of our clients. For example, a hydrogeologic study conducted for a civil engineer or architect may not fulfill the needs of a construction contractor or even another civil engineer or architect that are involved in the same project. Because each hydrogeologic study is unique, each hydrogeologic report is unique, prepared solely for the specific client and project site. Our report is prepared for the exclusive use of Snohomish County Public Utilities District No. 1. No other party may rely on the product of our services unless we agree in advance to such reliance in writing. This is to provide our firm with reasonable protection against open-ended liability claims by third parties with whom there would otherwise be no contractual limits to their actions. Within the limitations of scope, schedule and budget, our services have been executed in accordance with our Agreement with Tacoma Public Utilities and generally accepted geotechnical practices in this area at the time this report was prepared. This report should not be applied for any purpose or project except the one originally contemplated. A Hydrogeologic Report is Based on a Unique Set of Project-Specific Factors This report has been prepared for the proposed Pole Yard site in Arlington, Washington. GeoEngineers considered a number of unique, project-specific factors when establishing the scope of services for this project and report. Unless GeoEngineers specifically indicates otherwise, do not rely on this report if it was: â– not prepared for you, â– not prepared for your project, â– not prepared for the specific site explored, or â– completed before important project changes were made. For example, changes that can affect the applicability of this report include those that affect: â– the function of the proposed structure; â– elevation, configuration, location, orientation or weight of the proposed structure; â– composition of the design team; or â– project ownership. 2 Developed based on material provided by ASFE, Professional Firms Practicing in the Geosciences; www.asfe.org. April 26, 2016 | Page B-1 File No. 0482-051-03 If important changes are made after the date of this report, GeoEngineers should be given the opportunity to review our interpretations and recommendations and provide written modifications or confirmation, as appropriate. Subsurface Conditions Can Change This hydrogeologic report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by manmade events such as construction on or adjacent to the site, or by natural events such as floods, earthquakes, slope instability or ground water fluctuations. Always contact GeoEngineers before applying a report to determine if it remains applicable. Topsoil For the purposes of this report, we consider topsoil to consist of generally fine-grained soil with an appreciable amount of organic matter based on visual examination, and to be unsuitable for direct support of the proposed improvements. However, the organic content and other mineralogical and gradational characteristics used to evaluate the suitability of soil for use in landscaping and agricultural purposes was not determined, nor considered in our analyses. Therefore, the information and recommendations in this report, and our logs and descriptions should not be used as a basis for estimating the volume of topsoil available for such purposes. Most Hydrogeologic Findings Are Professional Opinions Our interpretations of subsurface conditions are based on field observations from widely spaced sampling locations at the site. Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field and published data and then applied our professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ, sometimes significantly, from those indicated in this report. Our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. Read These Provisions Closely Some clients, design professionals and contractors may not recognize that the geoscience practices (hydrogeology or geology) are far less exact than other engineering and natural science disciplines. This lack of understanding can create unrealistic expectations that could lead to disappointments, claims and disputes. GeoEngineers includes these explanatory â€œlimitationsâ€ provisions in our reports to help reduce such risks. Please confer with GeoEngineers if you are unclear how these â€œReport Limitations and Guidelines for Useâ€ apply to your project or site. Hydrogeologic, Geotechnical, Geologic and Environmental Reports Should not be Interchanged The equipment, techniques and personnel used to perform an environmental study differ significantly from those used to perform a hydrogeologic, geotechnical or geologic study and vice versa. For that reason, a geotechnical engineering or geologic report does not usually relate any environmental findings, conclusions or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Similarly, environmental reports are not used to address geotechnical or geologic concerns regarding a specific project. April 26, 2016 | Page B-2 File No. 0482-051-03 Biological Pollutants GeoEngineersâ€™ Scope of Work specifically excludes the investigation, detection, prevention, or assessment of the presence of Biological Pollutants in or around any structure. Accordingly, this report includes no interpretations, recommendations, findings, or conclusions for the purpose of detecting, preventing, assessing, or abating Biological Pollutants. The term â€œBiological Pollutantsâ€ includes, but is not limited to, molds, fungi, spores, bacteria, and viruses, and/or any of their byproducts. April 26, 2016 | Page B-3 File No. 0482-051-03 Have we delivered World Class Client Service? Please let us know by visiting www.geoengineers.com/feedback. Plaza 600 Building 600 Stewart Street, Suite 1700 Seattle, Washington 98101 206.728.6274 June 28, 2016 Snohomish County PUD No. 1 Facilities Department 2320 California Street Everett, Washington 98201 Attention: Ben Davis, PE Subject: Response Letter Wetlands/Streams Proposed Arlington Local Office Replacement and Substation Arlington, Washington File No. 0482-051-03 GeoEngineers, Inc. (GeoEngineers) understands that the project site (Figure 1) located near 180th Street NE and 59th Avenue NE in Arlington, Washington is being developed for a new local office building, access roadways, solar arrays, substation, and a pole and transformer storage area for the Snohomish County PUD No. 1 (SnoPUD). The site is located immediately east of the Arlington Municipal Airport. Development of the pole and transformer storage area will include constructing gravel laydown areas, asphalt paved roadways, and installation of a waterline. GeoEngineers further understands that design of the local office building, other roadways, solar arrays, and the substation will occur at a later date. SnoPUD requested that GeoEngineers complete a wetland reconnaissance of the site to provide our opinion related to wetlands that may be located on the project site. Following your request, GeoEngineersâ€™ Professional Wetland Scientist (PWS), performed a reconnaissance of the site on March 16, 2016. The PWS accessed the site via the man-gate along the southern property line and conducted a pedestrian survey of the property. General site observations of the approximate 26-acre parcel verified that the project site is Photo 1. Representative condition of the site, May 10, 2016. Snohomish County PUD No. 1 | June 28, 2016 Page 2 undeveloped and relatively flat uplands with no structures except for an abandoned barn located near the north-central portion of the project site (Photo 1). The parcel is predominantly vegetated with mowed grasses, forbs and Scotch broom (Cytisus scoparius); as well as, trees including big leaf maple (Acer macrophyllum), Douglas fir (Pseudotsuga menziesii) and ornamental apple (Malus spp.) which are indicative of uplands. While on site, GeoEngineersâ€™ PWS looked for wetland indicators such as changes in vegetation type, depressional areas and the presence of surface water. However, no wetlands were observed on the site during the pedestrian survey. Precipitation data collected at the Arlington Airport (Weather Underground, 2016) indicates 0.77 inches of rain near the site in the week preceding our March site visit. There was no surface water observed on site; however, a ditch was observed immediately east of the site and adjacent to the Burlington Northernâ€“ Santa Fe (BNSF) railroad line. Presumably this ditch is owned and maintained by BNSF. The average wetted width of the ditch was approximately 4 to 5 feet wide and appeared to be flowing slowly south at approximately 0.5 foot per second. Average depth of the wetted channel was approximately 12 inches. The east bank of the ditch has no vegetation and is covered in rail ballast extending into the ditch (Photo 2). The west bank of the channel is fully vegetated and covered with willows (Salix spp.), Himalayan blackberry (Rubus armeniacus), red alder (Alnus rubra) and cottonwood (Populus balsamifera) trees. No fish were observed in the ditch by the PWS. Following the March 16 site visit, the GeoEngineers PWS reviewed available public data regarding the ditch observed along the eastern boundary of the site. The Washington State Department of Fish and Wildlife (WDFW, 2016a), the Washington State Department of Natural Resources (WDNR, 2016) and Snohomish County (2016) do not map streams or waterways within the project boundary. WDFW (2016b) maps an â€œintermittent/ephemeralâ€ water course traversing the site from the northeast corner to the south-central portion of the site prior to leaving the property. We did not observe features at the site as mapped by WDFW (2016b). Based on our observations and data obtained from other sources, we believe that there are substantial errors in the WDFW (2016b) mapping data. The City of Arlington Stormwater Infrastructure Map (2016a) indicates the ditch along the eastern edge of the site conveys flows from a series of stormwater ponds located approximately 2,500 feet north of the site, near the intersection of 67th Ave NE and Woodlands Way. These stormwater ponds collect runoff from a larger residential development located southeast of the ponds. According to the City of Arlington (2016), the ditch flows south along the BNSF railway, past the eastern edge of the site and is eventually collected within the closed stormwater system of the developed area located south of the site. File No. 0482-051-03 Snohomish County PUD No. 1 | June 28, 2016 Page 3 The GeoEngineers PWS returned to the site on May 10, 2016 to verify public data and investigate the hydrology of the ditch. Precipitation data collected at the Arlington Airport (Weather Underground, 2016) indicates very little rain (0.02 inches) in the week prior to the May site visit. The ditch (Photo 2) was completely dry with vegetation establishing in the bed of the channel. We observed indications of recent inundation but it appears that this ditch experiences intermittent flow. This ditch is likely inundated during the winter when shallow groundwater is elevated and surface runoff is high. However, the ditch is not expected to flow perennially. As mapped by the City of Arlington (2016a), we observed less than 0.5 cubic feet per second (cfs) of flow from the stormwater ponds located 2,500 feet north of the site into a closed conveyance in the 67th Avenue NE right-of-way. Because of private property access issues, the PWS was not able to observe the mapped outfall of this stormwater system into the ditch adjacent to the BNSF railway. Most likely, the ditch adjacent to the BNSF railway conveys flow from the stormwater system located north of the site. According to Marc Hayes, City of Arlington Manager of Community and Economic Development (2016), smaller volumes, such as the 0.5 cfs observed Photo 2. Ditch adjacent to site, May 10, 2016. entering the stormwater system on May 10, 2016, likely infiltrate into the sandy substrate of the nearly level ditch prior to flowing past the site. We expect the ditch to be inundated only after periods of rain and runoff from the developed areas east of the site. It is our opinion that this ditch primarily functions as a stormwater conveyance and infiltration feature. We observed inundation in the ditch approximately 450 feet south of the site. At this location we observed water flowing into the ditch from a 24-inch round concrete pipe culvert that conveys flow under the BNSF railway from the area east of the railway. The City of Arlington (2016a) identifies the area east of the BNSF railway as constructed stormwater feature. Based on our observations, available map data and professional experience on similar sites, it is GeoEngineersâ€™ opinion that wetlands and stream features, regulated under City of Arlington Code Chapter 20.88.700 and 28.88.800 are not located within or adjacent to the site. REFERENCES City of Arlington. 2016a. Stormwater Inventory Map, dated April 15, 2015. http://www.arlingtonwa.gov/modules/showdocument.aspx?documentid=6637 Accessed May 2016. City of Arlington. 2016b. Personal communication between Marc Hayes (City of Arlington Manager of Community and Economic Development) and Ben Davis (SnoPUD). May 13, 2016. File No. 0482-051-03 Stormwater Stormwater Pond Pond Project Site Ditch Stormwater Pond Legend Approximate Site Boundary Not to Scale Site Map Notes: Arlington Office Replacement/Substation 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing Arlington, Washington features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Figure 1 Data Source: U.S. Fish and Wildlife Service National Wetland Inventory Map 00482-051-03 Date Exported: 04/26/16 MEMORANDUM To: Eric Scott, PE, City of Arlington From: Brad Lincoln, PE Subject: Arlington Pole Yard Date: April 21, 2016 Project: GTC #16-068 Gibson Traffic Consultants, Inc. (GTC) has been retained to provide a traffic analysis for the proposed Arlington Pole Yard development. The development is located on the east side of 59th Avenue NE, between 180th Street NE and 172nd Street NE in the City of Arlington. A site vicinity map is included in Figure 1. Specifically, this memorandum addresses the trip generation, trip distribution, access analysis and traffic mitigation fees. The site is currently vacant. The pole yard will be one of several things that maybe be developed at some future date on this site; however, this memorandum only focuses on the pole yard. Brad Lincoln, responsible for this memorandum, is a licensed professional engineer (Civil) in the State of Washington and member of the Washington State section of ITE. 1. TRIP GENERATION There is an existing similar pole yard located in the City of Arlington. Counts at the existing pole yard and information from the client were utilized to determine the trip generation from the proposed pole yard site. The client provided the following information regarding the operations of the pole yard: ï‚· There are no permanent employees on site ï‚· Employees visit the site at varying times between 7:00 AM and 3:45 PM ï‚· Visits include picking-up and dropping-off power poles ï‚· Access gates are closed and locked on a typical weekday by 4:00 PM The Arlington Pole Yard is anticipated to generate between 8 and 10 daily trips using the operations information from the client. There is one trip that might occur during the AM peak-hour and one of that might occur during the PM peak-hour. 2802 Wetmore Avenue ï‚ Suite 220 ï‚ Everett WA, 98201 Tel: 425-339-8266 ï‚ Fax: 425-258-2922 ï‚ E-mail: info@gibsontraffic.com D R N R U B 132ND ST NE MAP GTC #16-068FIGURE 1 SITE VICINITY TRAFFIC IMPACT STUDY 204TH ST NE 67TH AVE NE T S H T 7 9 1 63RD AVE SITE PROJECT 132ND ST NE 188TH ST NE ENEVAHT95 152ND ST NE N 4/19/2016 51ST AVE NE CEMETERY RD47TH AVE DEVELOPMENT SITE 188TH ST NE 168TH ST NE D BLV NT 204TH ST NE POI EY OK LEGEND SM 136TH ST NE ONSULTANTS C 27TH AVE NE RAFFIC T 140TH ST NE116TH ST NE 172ND ST NE IBSON G CITY OF ARLINGTON ARLINGTON POLE YARD Arlington Pole Yard Traffic Analysis A count at the existing site was also performed by the independent count firm, TDG on April 14, 2016 during the PM peak-hour to confirm the anticipated trip generation. One heavy vehicle entered the pole yard and two heavy vehicles exited the pole yard 15 minutes before the PM peak-hour of 4:00 PM to 5:00 PM. There were not any trips that occurred during the two hour 4:00 PM to 6:00 PM count period. The new pole yard will be similar in size and use to the existing pole yard and is therefore not anticipated to be a significant trip generator. 2. TRIP DISTRIBUTION The Arlington Pole Yard development will generate less than 10 peak-hour trips during the AM and PM peak-hours. A trip distribution should therefore not be required for the Arlington Pole Yard development. 3. ACCESS ANALYSIS The Arlington Pole Yard is proposed to have a temporary access to 180th Street NE approximately 0.25 miles east of 59th Avenue NE during construction. A permanent access to 59th Avenue NE approximately 0.28 miles north of 172nd Street NE is proposed. Both locations have sufficient sight distances to meet City of Arlington requirements. 4. MITIGATION The Arlington Pole Yard is anticipated to generate 1 PM peak-hour trips due to the possibility of a vehicle leaving the site late. The Arlington Pole Yard development should therefore only be required to pay traffic mitigation fees for one PM peak-hour trip. The City of Arlington has a mitigation fee of $3,355 per PM peak-hour trip. This results in a mitigation fee to the City of Arlington of $3,355.00. Gibson Traffic Consultants, Inc. April 2016 info@gibsontraffic.com 3 GTC #16-068 Attachments TURNING MOVEMENTS DIAGRAM 3:45 PM - 5:45 PM PEAK HOUR: 4:00 PM TO 5:00 PM Peds = 2 Turn- Bicycles0 U 0 0 0 0 0 0 Power Station Driveway Tveit Road Tveit Road 0 0 Bicycles 44 44 44 0 0 U-Turn U-Turn 0 0 Peds = 2 Peds = 0 65 65 65 Bicycles 0 0 0 0 0 HV PHF 0 0 INTERSECTION SB #N/A #N/A PEAK HOUR VOLUME 0 0 NB #N/A #N/A IN 109 Turn- WB 4.5% 0.92 Pole Yard Driveway U Bicycles OUT 109 EB 4.6% 0.71 Peds = 4 INTRS. 4.6% 0.78 PHF = Peak Hour Factor HV = Heavy Vehicle Tveit Road @ Power Station Driveway/Pole Yard Driveway Arlington, WA COUNTED BY: CN DATE OF COUNT: Thu. 4/14/16 REDUCED BY: CN TIME OF COUNT: 3:45 PM - 5:45 PM REDUCTION DATE: Thu. 4/14/16 WEATHER: Sunny 0 0 0 0 0 0 0 0 30 23 21 30 35 20 24 26 109 4.6% 0.78 0 0 0 0 0 0 0 0 104 109 106 109 105 INTERVAL TOTALS 4/14/2016 INTERVAL TOTALS CN Sunny INTERSECTION 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 Right Right Thru 0 0 0 0 0 0 0 0 18 11 13 18 23 15 19 19 65 Thru 0 0 0 0 0 0 0 0 60 65 69 75 76 65 0.71 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Left Left COUNTED BY: WEATHER: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 U-Turn U-Turn Tveit Road Tveit Road FROM WEST ON HV 0 0 0 0 0 0 0 0 3 2 0 0 1 1 0 0 3 FROM WEST ON HV 0 0 0 0 0 0 0 0 5 3 2 2 2 4.6% 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bicycle Bicycle 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 2 0 0 0 0 0 0 0 0 0 2 2 2 2 Peds DATE OF REDUCTION: Peds 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Right Right Thru 0 0 0 0 0 0 0 0 9 12 8 12 12 5 5 7 44 Thru 0 0 0 0 0 0 0 0 41 44 37 34 29 5:00 PM 44 0.92 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 TO 0 0 0 0 0 0 0 0 0 0 0 0 0 Left Left 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 U-Turn U-Turn Tveit Road Tveit Road FROM EAST ON HV 0 0 0 0 0 0 0 0 0 1 1 0 0 1 0 0 2 FROM EAST ON HV 0 0 0 0 0 0 0 0 2 2 2 1 1 4.5% Thu. 4/14/16 3:45 PM - 5:45 PM 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bicycle Bicycle 4:00 PM 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Peds Peds 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Right Right 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Thru Thru DATE OF COUNT: TIME OF COUNT: 0 #N/A 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 ROLLING HOUR COUNT 0 0 0 0 0 0 0 0 2 0 0 0 0 Left Left 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 U-Turn U-Turn FROM SOUTH ON HV 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 FROM SOUTH ON HV 0 0 0 0 0 0 0 0 2 0 0 0 0 Pole Yard Driveway #N/A 3:45 PM - 5:45 PM PEAK HOUR: Pole Yard Driveway INTERSECTION TURNING MOVEMENTS REDUCTION SHEET 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bicycle Bicycle 0 0 0 0 0 0 0 0 5 4 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 9 4 0 0 0 Peds Peds 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Right Right 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Thru Thru 0 #N/A 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Left Left 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 U-Turn U-Turn HV 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 HV 0 0 0 0 0 0 0 0 0 0 0 0 0 FROM NORTH ON #N/A FROM NORTH ON Power Station Driveway Power Station Driveway 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bicycle Bicycle 0 0 0 0 0 0 0 0 0 0 0 0 2 2 0 0 2 CN 0 0 0 0 0 0 0 0 0 2 4 4 4 Tveit Road @ Power Station Driveway/Pole Yard Driveway Arlington, WA Peds Peds AT TIME % HV INTERVAL ENDING 02:00 PM 02:15 PM 02:30 PM 02:45 PM 03:00 PM 03:15 PM 03:30 PM 03:45 PM 04:00 PM 04:15 PM 04:30 PM 04:45 PM 05:00 PM 05:15 PM 05:30 PM 05:45 PM FACTOR PEAK HOUR TIME INTERVAL ALL MOVEMENTS LOCATION: PEAK HOUR TOTALS HV = Heavy Vehicle PHF = Peak Hour Factor REDUCED BY: 1:45 PM - 2:45 PM 2:00 PM - 3:00 PM 2:15 PM - 3:15 PM 2:30 PM - 3:30 PM 2:45 PM - 3:45 PM 3:00 PM - 4:00 PM 3:15 PM - 4:15 PM 3:30 PM - 4:30 PM 3:45 PM - 4:45 PM 4:00 PM - 5:00 PM 4:15 PM - 5:15 PM 4:30 PM - 5:30 PM 4:45 PM - 5:45 PM 238 N Olympic Avenue REVIEW COMMENT FORM Arlington, WA 98223 360-403-3551 Project Name: PUD Equipment & Pole Yard Permit No.: 708 Review Date: 9/14/2016 Contact: Ben Davis Phone No.: 425 783-8465 Review Phase:1 Report Date: Reviewing Dept.: CED Applicant: Snohomish County PUD DWG Issue Date: # Rev. Dwg. or Addâ€™l Ref. City Comment Response/Resolution Spec. Ref. Approved 1. MH Sht. C-1 Since the City is requiring an easement, with legal description, for the water main extension within the proposed 63rd Ave. alignment it may make more sense to just create the legal for the Right of Way dedication at this time instead of later. The dedication process would have no impact on the project schedule. 2. MH Sht. C-2 Please provide a copy of the agreement between the PUD and AAMP regarding access and utility easement. 3. MH Sht. C-3 Tree mitigation for significant trees; replacement at a 3:1 ratio, or pay in lieu of to the cityâ€™s tree replacement fund. 4. MH Sht. C-7 4â€ ATB required in existing/future Right of Way. 5. MH Sht. C-8 Why is there a â€œnotchâ€ shown in proposed asphalt section at north end? If itâ€™s because of existing asphalt, please remove and replace with new asphalt section. Please shift the proposed access road 3â€™ to the west to better align with the future 63rd Ave. 6. MH Sht. C-14 Provide a minimum burial depth of 48â€ bgs, for the water main extension. 7. MH General All reports/studies/analysis and mitigations are accepted as submitted. 8. GS Water At Point of Connection on the south property line at item #4: The existing main is a 12" D.I. Also at this location install a 12" tee with a valve for future connection with 59th Avenue. 9. GS Water Re-orient compass 10. GS Water At point of connection by lot #4 do an 8" hot tap instead of a cut in tee, use 8" D.I. to connect to the 12" D.I. with an 8" x 12" reducer. 11. GS Water The 12" D.I. will need to be connected to the 12" Transmission main on the north side of 180 St. N.E. Page 1 of 3 238 N Olympic Avenue REVIEW COMMENT FORM Arlington, WA 98223 360-403-3551 Project Name: PUD Equipment & Pole Yard Permit No.: 708 Review Date: 9/14/2016 Contact: Ben Davis Phone No.: 425 783-8465 Review Phase:1 Report Date: Reviewing Dept.: CED Applicant: Snohomish County PUD DWG Issue Date: # Rev. Dwg. or Addâ€™l Ref. City Comment Response/Resolution Spec. Ref. Approved 12. GS Water On the construction notes add: (18) All in-line pipe joints shall be restrained with "Field Lock" type gaskets (19) All fittings shall be restrained joints and have thrust blocking. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. Page 2 of 3 238 N Olympic Avenue REVIEW COMMENT FORM Arlington, WA 98223 360-403-3551 Project Name: PUD Equipment & Pole Yard Permit No.: 708 Review Date: 9/14/2016 Contact: Ben Davis Phone No.: 425 783-8465 Review Phase:1 Report Date: Reviewing Dept.: CED Applicant: Snohomish County PUD DWG Issue Date: # Rev. Dwg. or Addâ€™l Ref. City Comment Response/Resolution Spec. Ref. Approved 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. Page 3 of 3 REVIEW COMMENT SUMMARY AND RESOLUTION SHEET Submittal: Snohomish County PUD No.1 Arlington Electrical Equipment and Pole Storage Yard CODE A. Incorporated B. Open/Under Review Agency/Company/Reviewer C. Evaluated/Not Incorporated D. Beyond Scope/Not Evaluated Robert O'Brien E. Clarify or discuss Submittal Date: 9/16/2016 X. Comment closed Comment Final Dwg No. Specification Correction Disposition Item No. Reviewer or Reference Review Comment Response Verification Page No. Chapter/Section Code (initials) 1 O'Brien Hydraulic Report Provide informaiton for stormwater mitigation for the offsite See Section 3 of the revised Stormwater Site Plan Page 4 improvments and increase in impervious area. Provide a downstream which has been added to discuss off-site analysis to show no impacts in temporary condition if temporary improvements and resulant no impacts. stormwater facilities are not constructed. 2 O'Brien WWHM Results Update WWHM model to reflect actual proposed cross section and Complete. See Appendix B of the revised include results to show water surface elevations remains in 4-inch Stormwater Site Plan. crushed aggragegate below treatment layer. 3 O'Brien C3 Provide silt fencing along north and northeast areas of spread Complete. Silt fence is now required on the north, Demolitions & strippings and excavated material area. Although the site historically east and west project limits. See Sheet C3 included TESC Plan drains south, the added elevation of the mounded strippings and in the revised Stormwater Site Plan. excavated soil will cause new flow paths around and from the mounded soil. Table of Contents 1.0 Project Overview ....................................................................................................................1 2.0 Existing Conditions Summary ...............................................................................................3 3.0 Off-Site Improvements ...........................................................................................................4 4.0 Off-site Analysis Report .........................................................................................................6 5.0 Minimum Requirements ........................................................................................................7 Governing Guidelines ...............................................................................................................9 Design Criteria ..........................................................................................................................9 6.0 Stormwater Control Plan .....................................................................................................16 Existing Site Hydrology .........................................................................................................16 Developed Site Hydrology .....................................................................................................16 Performance Standards and Goals ..........................................................................................17 7.0 Stormwater Pollution Prevention Plan (SWPPP) ..............................................................18 8.0 Special Reports and Studies .................................................................................................19 9.0 Other Permits ........................................................................................................................20 Table of Figures Figure 1 â€“ Vicinity Map .................................................................................................................2 Figure 2 â€“ Off-site Drive Aisle Aerial (2009) ...............................................................................5 Figure 3 - Flow Chart for Determining Requirements for New Development ........................8 List of Appendices Appendix A â€“ Improvement Plans Appendix B â€“ Flow Control Appendix C â€“ Runoff Treatment Appendix D â€“ Well Head Protection Zones Appendix E â€“ Soil Map Appendix F â€“ Operations and Maintenance Manual Stormwater Site Plan Page i Arlington Electrical Equipment &Pole Storage Yard July, 2016 1.0 Project Overview This Stormwater Site Plan Report provides stormwater requirements and design calculations for the proposed Snohomish County PUD No. 1 Arlington Electrical Equipment and Pole Storage Yard. The project property is located on 59th Ave NE south of the intersection with 180th Street NE, Arlington, WA 98223 within a portion of Section 22, Township 31, Range 5 East, WM. The project site is approximately 26.5 acres in area. Industrial uses border the site in all directions. 59th Ave NE borders the west side of the parcel, and railroad tracks owned by BNSF border the parcel to the east. A temporary storage yard adjacent to 59th Ave NE was constructed in 2013 creating 0.23 acres of gravel surfacing. There is no other impervious surfacing on-site. The site is predominately flat with slopes on average approximately 1-3 percent. The northeast corner of the site is approximately 10 feet higher than the western portion of the parcel. There are no known existing surface flows leaving the site. All stormwater runoff infiltrates onsite into existing outwash soils. Only a portion of the site will be developed. The 1.7 acre yard is centrally on the larger site. Access to the proposed yard will be via an access and utility easement on the AAMP (northern property owner) property. The access easement will provide a paved surface (with a minimum width of 20 feet) north to 180th Street NE and then west onto 59th Ave NE. The total disturbed area is approximately 5.0 acres. The developed storage yard is 1.7 acres in size finished with permeable gravel and asphalt. The remaining disturbed area will be used for on-site disposal of organic strippings. A water main will also be extended from the Pick and Pull site to the south connecting into the AAMP facility to the north. The proposed stormwater facilities will comply with the 2012 Department of Ecology Stormwater Management Manual for Western Washington (DOE Manual) and the City of Arlington Design and Construction Standards and Specifications. The pollution generating impervious surfaces (PGIS) will be treated by a water quality layer of material within the gravel surfacing prior to infiltrating into the existing subgrade. Refer to Section 4 of this report for additional information on the proposed drainage systems. Stormwater Site Plan Page 1 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Figure 1 â€“ Vicinity Map Project Site Stormwater Site Plan Page 2 Arlington Electrical Equipment &Pole Storage Yard July, 2016 2.0 Existing Conditions Summary The project site is approximately 26.5 acres in area. The project consists of one parcel. There is a small building, approximately 2,000 square feet centrally located on the parcel. The building, a dilapidated barn, is the only structure onsite. The rest of the parcel is vegetated predominately with grass and shrubs. There are a few trees scattered throughout the site. To the north of the site are multiple larger buildings (warehouses), and to the south of the site is a parking lot and miscellaneous buildings. The site is predominately flat with slopes on average approximately 1-3 percent. The northeast corner of the site is approximately 10 feet higher than the western portion of the parcel. There are no known existing flows leaving the site. All stormwater runoff infiltrates onsite into the existing soils. According to the Natural Resources Conservation Service (NRCS), the soils on the project site primarily consist of Lynnwood loamy sands with 0-3 % slopes with a Hydrologic Soil Group Type A. A Type A soil was used in WWHM3 for stormwater facility sizing purposes. GeoEngineers completed a geotechnical engineering report establishing a minimum of 1.2 inches/hour as the estimated long-term infiltration which was used in facility sizing. A portion of the site lies within a wellhead protection zone. A City of Arlington airport well is located approximately 2,000 feet north of the project site. The eastern half of the site which is where the proposed development is located is within the 1-year and 1-year buffer protection zones. See Appendix D for wellhead protection zone map. Stormwater Site Plan Page 3 Arlington Electrical Equipment &Pole Storage Yard July, 2016 3.0 Off-Site Improvements In order to establish paved access for emergency vehicles approximately 8,080 square feet of a gravel parking lot will be paved with asphalt treated base. The proposed improvements are temporary until AAMP (property owner to the north) and/or the City of Arlington construct full roadway improvements as described in â€œAgreement for Deferral of Inprovementsâ€ recording number 201112200120. The area to be paved was historically a parking lot for Bayliner employees (see Figure 2). Since the AAMP property was redeveloped (about 2011) the parking area has largely been unused. The conversion of this area to a paved surface will not impact the larger infiltration storm system that was designed to handle drainage from the gravel parking area with similar runoff characteristics. In addition the project adds less than 10,000 square feet of impervious surfacing and causes less than a 0.1 cubic feet per second increase in the 100- year flow frequency because all drainage will continue to infiltrate into the existing storm system. In accordance with threshold applicability of Minimum Requirement #7: Flow Control no additional storm drainage facilities are proposed other than those currently in operation at the AAMP facility. Stormwater Site Plan Page 4 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Figure 2 â€“ Off-site Drive Aisle Aerial (2009) Stormwater Site Plan Page 5 Arlington Electrical Equipment &Pole Storage Yard July, 2016 4.0 Off-site Analysis Report This section evaluates the upstream and downstream drainage system. The intent of this section is to identify any existing or potential drainage impacts created or exacerbated by the proposed project and drainage facilities. Task 1: Study Area Definition The offsite analysis study area was conducted with the use of Snohomish County GIS aerial and topographic information and a topographic survey of the site. Task 2: Review of available information The following resources were utilized in preparation of this section: USGS Topographic Map Snohomish County PDS Permit, Planning and Zoning Interactive Map City of Arlington Wellhead protection Zone Map National Resources Conservation Service Web Soil Survey Task 3: Upstream & Downstream Study An upstream and downstream study was not completed because there is no upstream drainage basin and all stormwater infiltrates into the existing site soils. Stormwater Site Plan Page 6 Arlington Electrical Equipment &Pole Storage Yard July, 2016 5.0 Minimum Requirements Not all of the Minimum Requirements apply to every development or redevelopment project. The applicability varies depending on the type and size of the project. This section identifies thresholds that determine the applicability of the Minimum Requirements to different projects. The flow chart below identifies the applicable requirements. Stormwater Site Plan Page 7 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Figure 3 - Flow Chart for Determining Requirements for New Development Start Here Does the site have Yes See Redevelopment 35% or more of Minimum existing impervious Requirements and coverage? Flow Chart (Figure 2.3) No Does the project convert Â¾ acres of native vegetation to Does the project add No lawn or landscaped 5,000 square feet or areas, or convert 2.5 more of new acres of native impervious surfaces? vegetation to pasture? Yes No Yes Does the project have 2,000 square feet or All Minimum more of new, replaced, Requirements apply to or new plus replaced the new impervious impervious surfaces? surfaces and converted pervious surfaces. Yes No Minimum Does the project have Requirements #1 land-disturbing through #5 apply to activities of 7,000 the new and replaced Yes square feet or more? impervious surfaces and the land disturbed. No See Minimum Requirement #2, Construction Stormwater Pollution Prevention Stormwater Site Plan Page 8 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Governing Guidelines The project site is located within the City of Arlington. The Washington State Department of Ecology Stormwater Management Manual for Western Washington, 2012 (DOE Manual) will be used for stormwater design. The Western Washington Hydrology Model Version 2012 (WWHM), a continuous simulation model will be used to size all stormwater facilities. Design Criteria Per Figure 8 in the DOE Manual â€“ Flow chart for determining requirements for new development â€“ all minimum requirements apply to the area of the site being developed. The following section describes how each Minimum Requirement (MR) will be incorporated into the proposed project. MR #1 through #10 are addressed as follows: MR #1: Preparation of Stormwater Site Plans. This report and accompanying improvement plans constitute the Stormwater Site Plan. MR #2: Construction Stormwater Pollution Prevention (SWPPP). A SWPPP will be prepared as a separate document for use during construction. Even though the project likely does not require coverage by a Department of Ecolgoy Construction Stormwater General Permit due to on-site infiltration the District will obtain coverage in the unlikely event construction stormwater leaves the project site. The following section provides a detailed description of the BMPs to be implemented based on the 12 required elements of the SWPPP. For additional information refer to the project TESC plans and SWPPP. Element #1 â€“ 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. A large portion of the site will remain undisturbed throughout construction. Clearing limits will be delineated by silt fence and high visibility fence. The following relevant BMPs for this project include: BMP C101: Preserving Natural Vegetation BMP C233: Silt Fence BMP C103: High Visibility Plastic or Metal Fence Element #2 â€“ Establish Construction Access Stormwater Site Plan Page 9 Arlington Electrical Equipment &Pole Storage Yard July, 2016 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. The following relevant BMPs for this project include: BMP C105: Stabilized Construction Entrance BMP C107: Construction Road/Parking Area Stabilization Element #3 â€“ Control Flow Rates In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site will be controlled. The following relevant BMPs for this project include: Not applicable. It is anticipated that all construction stormwater will infiltrate into the existing subgrade. Element #4 â€“ Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before entering a receiving water body. The following relevant BMPs for this project include: BMP C220: Storm Drain Inlet Protection BMP C233: Silt Fence Element #5 â€“ 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 following relevant BMPs for this project include: BMP C120: Temporary and Permanent Seeding BMP C121: Mulching BMP C123: Plastic Covering 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. Element #6 â€“ Protect Slopes All cut and fill slopes shall be designed, constructed, and protected in a manner that minimizes erosion. The following relevant BMPs for this project include: Stormwater Site Plan Page 10 Arlington Electrical Equipment &Pole Storage Yard July, 2016 BMP C121: Mulching Element #7 â€“ Protect Permanent Drain Inlets All existing and proposed storm drain inlets and culverts made operable during construction that may receive stormwater on and downstream of the site shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. The following relevant BMPs for this project include: BMP C220: Storm Drain Inlet Protection Element #8 â€“ Stabilize Channels and Outlets There are no known channels and/or outlets on site to stabilize. Element #9 â€“ Control Pollutants All pollutants, including waste materials and demolition debris, that occur during construction 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. Vehicles, construction equipment, and/or petroleum product storage/dispensing: â€¢ 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. â€¢ Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. â€¢ Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. 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 C151). In order to prevent, reduce, or eliminate the discharge of pollutants from material delivery and storage to the stormwater system, Material Delivery and Storage Contamination (BMP C153) shall be implemented. Stormwater Site Plan Page 11 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Sanitary wastewater: Portable sanitation facilities will be firmly secured, regularly maintained, and emptied when necessary. Solid Waste: Solid waste will be stored in secure, clearly marked containers. Element #10 â€“ Control Dewatering Large scale dewatering is not anticipated during construction. A sedimentation bag with outfall into existing vegetation will be used for small volumes of localized de-watering. Element #11 â€“ 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 BMPâ€™s 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. Element #12 â€“ Manage the Project All BMPâ€™s shall be inspected and repaired in accordance with DOE permit requirements. The full project SWPPP will be kept on-site during construction. Element #13 â€“ Protect Low Impact Development BMPâ€™s The project does not have traditional low impact development BMPâ€™s. The project will utilize a custom biorention soil mix under a pervious gravel section for stormwater treatment. A geotechnical special inspection will be on-site during construction to verify the Contractor follows proper construction to no foul or over compact the pervious section material and/or subgrade. The District will also be providing periodic inspection to verify the TESC and SWPPP measures are properly installed and maintained throughout construction. MR #3: Source Control of Pollution. All known, available and reasonable Source Control BMPs shall be applied to this project. The District will promptly contain and clean up solid and liquid pollutant leaks and spills including oils and fuels. The District will periodically contract street sweeping to remove dust and debris that could contaminate stormwater and will not hose down Stormwater Site Plan Page 12 Arlington Electrical Equipment &Pole Storage Yard July, 2016 pollutants. The District will maintain the transformer storage area including periodic inspection of the oil stop valve and will repair the pavement and containment area if damaged. Any damaged and/or leaking equipment will promptly be removed from the site and repaired at the Districtâ€™s Operations Center. MR #4: Preservation of Natural Drainage Systems and Outfalls. The proposed stormwater site plan will maintain the existing outfall infiltrating into the existing subgrade. MR #5: On-Site Stormwater Management. The DOE Manual requires the use of on-site Stormwater Management BMPs to infiltrate, disperse, and retain stormwater runoff on-site to the maximum extent feasible without causing flooding or erosion impacts. Existing onsite soils and the proposed stormwater facility design allows for 100% infiltration of all proposed impervious and pervious surfaces from 50% of the 2 year peak flow up to the full 50 year peak flow as modeled by WWHM2012. MR #6: Runoff Treatment. The developed portion of the site will be used for industrial uses which requires enhanced water quality treatment per the DOE Manual. Treatment of stormwater runoff will be provided by a custom bioretention soil mix within the pervious (or gravel) areas. The custom bioretention soil mix complies with the Volume V, page 7-17 of the DOE Manual. A custom soil mix will be used due to a couple factors. The existing topsoil does have a cation exchange rate greater than five, however the depth of the topsoil is less than 18 inches which is insufficient for water quality treatment. The site will also be developed in the winter months which is not ideal for mixing and reuse of existing on-site materials. The paved access drives will be designed to sheet flow drainage into the pervious gravel sections for treatment prior to infiltration. The gravel areas have been designed to treat the tributary pavement areas. In order to allow for treatment within the 18â€ water quality section without backwatering during large storm events a 4â€ layer of rock was also incorporated into the gravel section to allow for ponding at the subgrade interface prior to infiltrating into the subgrade. The site design also incorporates a paved and curbed area for transformer storage. The transformers stored on-site are filled with a non-conductive mineral oil. Mineral oil transfer and/or filling will not occur on-site so the spill potential on-site is limited, however vandalism has resulted in oil spills of stored and/or operational transformer in the past. To reduce the risk of contaminating soil as a result of an accidental spill an oil stop valve and curbed area have been included in the site development plans. During Stormwater Site Plan Page 13 Arlington Electrical Equipment &Pole Storage Yard July, 2016 normal operations the transformer pavement area will drain onto the gravel section via a storm drain outlet and will be treated by the water quality section within the gravel section. The stormwater quality treatment design is discussed in more detail in Appendix C of this report. MR #7: Flow Control. All stormwater generated on the project site from the proposed impervious and pervious surfaces from 50% of the 2 year peak flow up to the full 50 year peak flow as modeled by WWHM2012 will infiltrate into the subgrade mimicking existing conditions. The long term infiltration rate of the subgrade soils has been established by grain size analysis conducted by GeoEngineers (see Geotechnical report dated May 4, 2016). GeoEngineers took several samples of the subgrade material at different locations and depths on the 26.5 acre site. The site soils are consistent briefly described as sand with a higher percentage of silt at lower depths. The proposed gravel section will require stripping a minimum of 2.5â€™ from the existing site for construction of the proposed section. The low long-term infiltration rate calculated by GeoEngineers is 1.2 inches/hour at 3 feet below existing grade. The high long-term infiltration rate calculated by GeoEngineers is 7.7 inches/hour at 6 feet below existing grade. For design of the infiltration facilities a conservative rate of 1.2 inches per hour was used to verify 100% infiltration and that ponding of water at the subgrade line did not backwater into the treatment section. The DOE Manual in Volume III, page 3-85 states that the base of all infiltration basins or trenches shall be greater or equal to 5 feet above the seasonal high water mark. This can be reduced to 3 feet with a groundwater mounding analysis. A Hydrogeologic Assessment was completed to support the site development and address this design constraint as well as discuss the sole source aquifer and it relates to the proposed site development in more detail. Two data loggers were installed and measured seasonal groundwater elevations during the rainy season for several years. In general terms the groundwater elevation from existing subgrade deepens from the south property line to the north. The maximum recorded groundwater elevation below existing grade near the middle of the site is approximately 7 feet. The maximum recorded groundwater elevation below existing grade near the south end of the site is approximately 4 feet. The proposed development borders the north property line and the bottom of the proposed facilities 2.5 feet below existing grade. Assuming the seasonal groundwater level deepens to the north the designed facilities have the required separation. This is consistent with visual observations of two stormwater ponds on the AAMP property which border the development to the north. See separate Hydrogeologic Assessment completed by GeoEngineers dated April 26, 2016 for additional information. Stormwater Site Plan Page 14 Arlington Electrical Equipment &Pole Storage Yard July, 2016 The imported materials that will be placed on the prepared subgrade in the gravel areas have a low percentage of fines and will not restrict infiltration of stormwater into the subgrade. The subgrade is the confining layer of material and the infiltration rate through this material was used in design. The stormwater infiltration design is discussed in more detail in Appendix B of this report. MR #8: Wetlands Protection There are no wetlands or wetland buffers impacting the site. MR #9: Basin/Watershed Planning. A portion of the site lies within a wellhead protection zone. A City of Arlington airport well is located approximately 2,000 feet north of the project site. The proposed gravel section with an 18 inch water quality section will provide adequate treatment of stormwater prior to infiltration reducing potential impacts to the water source. See Appendix D for wellhead protection zone map. MR #10: Operation and Maintenance. An Operation and Maintenance Manual is included in Appendix F of this report. Stormwater Site Plan Page 15 Arlington Electrical Equipment &Pole Storage Yard July, 2016 6.0 Stormwater Control Plan The following section details the selection of stormwater control BMPs and facilities that will serve the proposed project in its developed condition. The selection of stormwater control and BMP facilities follows the 2012 DOE Manual. Existing Site Hydrology The project site is 26.5-acres in area with an old dilapidated barn in the center of the property. Vegetation of the site consists of recently mowed grasses, scotch broom, blackberry and a few large deciduous and conifer trees. The site is predominately flat with slopes of approximately 2 percent. The north east corner of the site is the high side, and gently slopes to the west. The west side of the site at NE 59th Street is the low side of the site. Off-site flows are limited. Properties to the north and south are developed with existing site drainage systems. There is no observed runoff coming from the project site. Based on site observation and the geotechnical report, the majority of all stormwater runoff infiltrates into the existing soils. Refer to the Geotechnical Report prepared for this project for additional soils information. Developed Site Hydrology Developed site conditions will mimic existing site drainage conditions by infiltrating stormwater runoff into the existing subgrade. Only a portion of the 26.5 acre site will be developed for creation of the proposed Arlington Electrical Equipment and Pole Storage Yard. The developed yard is approximately 1.7 acres. During development an additional 1.5 acres will be disturbed for on-site disposal of organic strippings. The paved access drives sheet flow drainage into the pervious gravel sections for treatment prior to infiltration. The gravel areas have been designed to treat tributary pavement areas with an 18â€ water quality section. The site design also incorporates a paved, curbed area with an oil stop valve for transformer storage to reduce the risk of contaminating soil as a result of an accidental spill. During normal operations the transformer pavement area will drain onto the gravel section via a storm drain outlet and will be treated by the water quality section within the gravel section. Stormwater Site Plan Page 16 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Performance Standards and Goals The stormwater facilities have been designed using the Western Washington Hydrology Model Version 2012. The stormwater discharges match developed discharge durations to pre-developed durations for the range of pre-developed discharge rates from 50% of the 2-year peak flow up to the full 50-year peak flow. WWHM2012 is based on continuous simulation hydrology and according to the 2012 SMMWW is acceptable for sizing infiltration and water quality facilities in Western Washington. The pre-developed condition is assumed to be forested with Type A/B soils. For further detailed information concerning the design of the stormwater facilities reference Appendices B & C. Stormwater Site Plan Page 17 Arlington Electrical Equipment &Pole Storage Yard July, 2016 7.0 Stormwater Pollution Prevention Plan (SWPPP) A site specific SWPPP will be provided prior to construction. Stormwater Site Plan Page 18 Arlington Electrical Equipment &Pole Storage Yard July, 2016 8.0 Special Reports and Studies â€¢ Critical Area Reconnaissance - GeoEngineers, Inc., June 28, 2016. â€¢ Geotechnical Engineering Report - GeoEngineers, Inc., May 4, 2016 â€¢ Hydrogeologic Assessment - GeoEngineers, Inc., April 26, 2016 â€¢ Traffic Analysis â€“ Gibson Traffic Consultants, Inc., April 21, 2016 â€¢ AHERA Inspection Report â€“ Snohomish County PUD No. 1, July 14, 2014 â€¢ Cultural Resources Assessment - Cultural Resources Consultants, July 8, 2016 Stormwater Site Plan Page 19 Arlington Electrical Equipment &Pole Storage Yard July, 2016 9.0 Other Permits â€¢ City of Arlington Grading Permit â€¢ City of Arlington Zoning Permit â€¢ City of Arlington Civil Permit â€¢ Washington State Department of Ecology Construction Stormwater General Permit â€¢ SEPA Threshold Determination (Snohomish County PUD No. 1 Lead Agency) â€¢ City of Arlington Avigation Easement Stormwater Site Plan Page 20 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Appendix A â€“ Improvement Plans Stormwater Site Plan Appendix A Arlington Electrical Equipment &Pole Storage Yard July, 2016 Lockey TE hydraulic closer sized to accommodate door. 09/22/2016 Appendix B â€“ Flow Control Stormwater Site Plan Appendix B Arlington Electrical Equipment &Pole Storage Yard July, 2016 Sedimentation and Erosion Control In our opinion, the erosion potential of the on-site soils is low to moderate. Construction activities, including stripping and grading, will expose soils to the erosion effects of wind and water. The amount and potential impacts of erosion are partly related to the time of year that construction actually occurs. Wet weather construction will increase the amount and extent of erosion and potential sedimentation. Erosion and sedimentation control measures may be implemented by using a combination of interceptor swales, straw bale barriers, silt fences and straw mulch for temporary erosion protection of exposed soils. All disturbed areas should be finish graded and seeded as soon as practicable to reduce the risk of erosion. Erosion and sedimentation control measures should be installed and maintained in accordance with the requirements of the City of Arlington. Infiltration Facilities We understand that the District is planning to design the unpaved gravel areas for stormwater infiltration at the site. We understand that the pole storage yard gravel surfacing section will be underlain by a bioretention soil mix layer for stormwater treatment. We also understand that infiltration requirements will be designed in accordance with the Washington State Department of Ecologyâ€™s 2012 SWMMWW. Since the soils have not been glacially consolidated, a pilot infiltration test (PIT) is not required in order to estimate an initial saturated hydraulic conductivity (Ksat) per Section 3.3.4 of the SWMMWW. The initial saturated hydraulic conductivity values were estimated using the grain size analysis method per Section 3.3.6 of the SWMMWW. We completed eight grain size analyses on selected samples from our explorations. The estimated long-term (factored) saturated hydraulic conductivity values for each sample is summarized in Table 5. TABLE 5. ESTIMATED LONG-TERM SATURATED HYDRAULIC CONDUCTIVITY Long-Term Rate (factored) Ksat USCS Depth D10 D60 D90 ffines Exploration Symbol (feet) (mm) (mm) (mm) (%) (cm/s) (in/hr) B-2 SP-SM 5 0.170 5.37 16.2 5.8 3.81 x 10-3 5.4 B-3 SM 2Â½ 0.040 0.61 8.6 13.2 1.62 x 10-3 2.3 B-5 SP-SM 5 0.100 3.07 25.5 8.1 1.76 x 10-3 2.5 TP-1 SP 6 0.120 0.31 0.7 3.7 4.52 x 10-3 6.4 TP-3 SP 6 0.230 1.22 13.3 2.6 5.43 x 10-3 7.7 TP-7 SP-SM 3 0.070 0.51 3.8 11.2 2.33 x 10-3 3.3 TP-8 SM 3 0.001 0.23 0.7 27.1 8.47 x 10-4 1.2 TP-8 SP 6 0.200 0.85 8.6 2.8 5.36 x 10-3 7.6 Notes: mm = millimeter; cm/s = centimeters per second; in/hr = inchers per hour Conservative Rate used for design May 4, 2016 | Page 12 File No. 0482-051-03 NORTH CENTER INFILTRATION AREA NORTH CENTER TRIBUTARY INFILTRATION AREA PAVEMENT AREA 5,746SF = 75.8^2SF 7,489 SF = 0.17AC WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Arlington (North Center) Site Name: PUD Pole Yard Site Address: 59th Ave NE City : Arlington Report Date: 10/3/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.20 Version Date: 2016/02/25 Version : 4.2.12 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : PreDev North Center Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .3 Pervious Total 0.3 Impervious Land Use acre Impervious Total 0 Basin Total 0.3 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : North Center Pervious Bottom Length: 75.80 ft. Bottom Width: 75.80 ft. Trench bottom slope 1: 0 To 1 Total gravel area is Trench Left side slope 0: 0 To 1 5,746 square feet Trench right side slope 2: 0 To 1 Material thickness of first layer: 0.6666666 Pour Space of material for first layer: 0.4 Material thickness of second layer: 1.5 Pour Space of material for second layer: 0.4 Material thickness of third layer: 0.333333 Pour Space of material for third layer: 0.4 Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 57.77 Total Volume Through Riser (ac-ft.): 0 No backwater into treatment layer Total Volume Through Facility (ac-ft.): 57.77 above 4 inches of rock at base of facility Percent Infiltrated: 100 Total Precip Applied to Facility: 26.715 Total Evap From Facility: 1.834 Discharge Structure Riser Height: 0.333333333 ft. Riser Diameter: 24 in. Precipitation applied to facility 5,746 sf 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 0.131 0.000 0.000 0.000 0.0148 0.131 0.000 0.000 0.159 0.0296 0.131 0.001 0.000 0.159 0.0444 0.131 0.002 0.000 0.159 0.0593 0.131 0.003 0.000 0.159 0.0741 0.131 0.003 0.000 0.159 0.0889 0.131 0.004 0.000 0.159 0.1037 0.131 0.005 0.000 0.159 0.1185 0.131 0.006 0.000 0.159 0.1333 0.131 0.007 0.000 0.159 0.1481 0.131 0.007 0.000 0.159 0.1630 0.131 0.008 0.000 0.159 0.1778 0.131 0.009 0.000 0.159 0.1926 0.131 0.010 0.000 0.159 0.2074 0.131 0.010 0.000 0.159 0.2222 0.131 0.011 0.000 0.159 0.2370 0.131 0.012 0.000 0.159 0.2519 0.131 0.013 0.000 0.159 0.2667 0.131 0.014 0.000 0.159 0.2815 0.131 0.014 0.000 0.159 0.2963 0.131 0.015 0.000 0.159 0.3111 0.131 0.016 0.000 0.159 0.3259 0.131 0.017 0.000 0.159 0.3407 0.131 0.018 0.013 0.159 0.3556 0.131 0.018 0.070 0.159 0.3704 0.131 0.019 0.151 0.159 0.3852 0.131 0.020 0.250 0.159 0.4000 0.131 0.021 0.365 0.159 0.4148 0.131 0.021 0.493 0.159 0.4296 0.131 0.022 0.633 0.159 0.4444 0.131 0.023 0.784 0.159 0.4593 0.131 0.024 0.946 0.159 0.4741 0.131 0.025 1.117 0.159 0.4889 0.131 0.025 1.297 0.159 0.5037 0.131 0.026 1.486 0.159 0.5185 0.131 0.027 1.682 0.159 0.5333 0.131 0.028 1.886 0.159 0.5481 0.131 0.028 2.097 0.159 0.5630 0.131 0.029 2.314 0.159 0.5778 0.131 0.030 2.537 0.159 0.5926 0.131 0.031 2.766 0.159 0.6074 0.131 0.032 3.000 0.159 0.6222 0.131 0.032 3.239 0.159 0.6370 0.131 0.033 3.482 0.159 0.6519 0.131 0.034 3.729 0.159 0.6667 0.131 0.035 3.979 0.159 0.6815 0.131 0.036 4.232 0.159 0.6963 0.131 0.036 4.487 0.159 0.7111 0.131 0.037 4.745 0.159 0.7259 0.131 0.038 5.004 0.159 0.7407 0.131 0.039 5.264 0.159 0.7556 0.131 0.039 5.525 0.159 0.7704 0.131 0.040 5.786 0.159 0.7852 0.131 0.041 6.047 0.159 0.8000 0.131 0.042 6.307 0.159 0.8148 0.131 0.043 6.566 0.159 0.8296 0.131 0.043 6.823 0.159 0.8444 0.131 0.044 7.078 0.159 0.8593 0.131 0.045 7.331 0.159 0.8741 0.131 0.046 7.580 0.159 0.8889 0.131 0.046 7.826 0.159 0.9037 0.131 0.047 8.068 0.159 0.9185 0.131 0.048 8.306 0.159 0.9333 0.131 0.049 8.540 0.159 0.9481 0.131 0.050 8.768 0.159 0.9630 0.131 0.050 8.991 0.159 0.9778 0.131 0.051 9.208 0.159 0.9926 0.131 0.052 9.419 0.159 1.0074 0.131 0.053 9.624 0.159 1.0222 0.131 0.053 9.823 0.159 1.0370 0.131 0.054 10.01 0.159 1.0518 0.131 0.055 10.20 0.159 1.0667 0.131 0.056 10.37 0.159 1.0815 0.131 0.057 10.54 0.159 1.0963 0.131 0.057 10.71 0.159 1.1111 0.131 0.058 10.86 0.159 1.1259 0.131 0.059 11.01 0.159 1.1407 0.131 0.060 11.15 0.159 1.1556 0.131 0.061 11.29 0.159 1.1704 0.131 0.061 11.41 0.159 1.1852 0.131 0.062 11.53 0.159 1.2000 0.131 0.063 11.65 0.159 1.2148 0.131 0.064 11.76 0.159 1.2296 0.131 0.064 11.86 0.159 1.2444 0.131 0.065 11.96 0.159 1.2593 0.131 0.066 12.05 0.159 1.2741 0.131 0.067 12.14 0.159 1.2889 0.131 0.068 12.22 0.159 1.3037 0.131 0.068 12.30 0.159 1.3185 0.131 0.069 12.38 0.159 ___________________________________________________________________ Name : Lateral I Basin 1 Bypass: No pavement tributuary to Impervious Land Use acre gravel area ROADS FLAT LAT 0.17 ___________________________________________________________________ Element Flows To: Outlet 1 Outlet 2 North Center Pervious ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.3 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.17 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000344 5 year 0.000747 10 year 0.001198 25 year 0.002092 50 year 0.003092 100 year 0.004485 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.000 1950 0.001 0.000 1951 0.000 0.000 1952 0.000 0.000 1953 0.000 0.000 1954 0.002 0.000 1955 0.001 0.000 1956 0.000 0.000 1957 0.000 0.000 1958 0.000 0.000 1959 0.001 0.000 1960 0.000 0.000 1961 0.001 0.000 1962 0.000 0.000 1963 0.000 0.000 1964 0.001 0.000 1965 0.000 0.000 1966 0.000 0.000 1967 0.000 0.000 1968 0.000 0.000 1969 0.000 0.000 1970 0.000 0.000 1971 0.001 0.000 1972 0.000 0.000 1973 0.000 0.000 1974 0.001 0.000 1975 0.000 0.000 1976 0.001 0.000 1977 0.000 0.000 1978 0.000 0.000 1979 0.000 0.000 1980 0.000 0.000 1981 0.000 0.000 1982 0.000 0.000 1983 0.000 0.000 1984 0.000 0.000 1985 0.000 0.000 1986 0.002 0.000 1987 0.001 0.000 1988 0.000 0.000 1989 0.000 0.000 1990 0.000 0.000 1991 0.000 0.000 1992 0.000 0.000 1993 0.000 0.000 1994 0.000 0.000 1995 0.000 0.000 1996 0.003 0.000 1997 0.007 0.000 1998 0.000 0.000 1999 0.000 0.000 2000 0.000 0.000 2001 0.000 0.000 2002 0.000 0.000 2003 0.000 0.000 2004 0.000 0.000 2005 0.000 0.000 2006 0.008 0.000 2007 0.000 0.000 2008 0.000 0.000 2009 0.000 0.000 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0080 0.0000 2 0.0074 0.0000 3 0.0027 0.0000 4 0.0021 0.0000 5 0.0017 0.0000 6 0.0014 0.0000 7 0.0013 0.0000 8 0.0012 0.0000 9 0.0011 0.0000 10 0.0008 0.0000 11 0.0007 0.0000 12 0.0006 0.0000 13 0.0005 0.0000 14 0.0005 0.0000 15 0.0005 0.0000 16 0.0005 0.0000 17 0.0005 0.0000 18 0.0004 0.0000 19 0.0004 0.0000 20 0.0004 0.0000 21 0.0004 0.0000 22 0.0004 0.0000 23 0.0003 0.0000 24 0.0002 0.0000 25 0.0002 0.0000 26 0.0002 0.0000 27 0.0002 0.0000 28 0.0002 0.0000 29 0.0002 0.0000 30 0.0002 0.0000 31 0.0002 0.0000 32 0.0002 0.0000 33 0.0002 0.0000 34 0.0002 0.0000 35 0.0002 0.0000 36 0.0002 0.0000 37 0.0002 0.0000 38 0.0002 0.0000 39 0.0002 0.0000 40 0.0002 0.0000 41 0.0002 0.0000 42 0.0002 0.0000 43 0.0002 0.0000 44 0.0002 0.0000 45 0.0002 0.0000 46 0.0002 0.0000 47 0.0002 0.0000 48 0.0002 0.0000 49 0.0002 0.0000 50 0.0002 0.0000 51 0.0002 0.0000 52 0.0002 0.0000 53 0.0002 0.0000 54 0.0002 0.0000 55 0.0002 0.0000 56 0.0002 0.0000 57 0.0002 0.0000 58 0.0002 0.0000 59 0.0002 0.0000 60 0.0002 0.0000 61 0.0002 0.0000 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0002 2363 0 0 Pass 0.0002 1352 0 0 Pass 0.0002 470 0 0 Pass 0.0003 112 0 0 Pass 0.0003 103 0 0 Pass 0.0003 89 0 0 Pass 0.0003 77 0 0 Pass 0.0004 66 0 0 Pass 0.0004 62 0 0 Pass 0.0004 58 0 0 Pass 0.0005 54 0 0 Pass 0.0005 50 0 0 Pass 0.0005 49 0 0 Pass 0.0006 47 0 0 Pass 0.0006 43 0 0 Pass 0.0006 40 0 0 Pass 0.0006 36 0 0 Pass 0.0007 36 0 0 Pass 0.0007 32 0 0 Pass 0.0007 31 0 0 Pass 0.0008 31 0 0 Pass 0.0008 29 0 0 Pass 0.0008 29 0 0 Pass 0.0009 27 0 0 Pass 0.0009 26 0 0 Pass 0.0009 26 0 0 Pass 0.0009 26 0 0 Pass 0.0010 25 0 0 Pass 0.0010 23 0 0 Pass 0.0010 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 21 0 0 Pass 0.0012 19 0 0 Pass 0.0012 18 0 0 Pass 0.0012 17 0 0 Pass 0.0013 16 0 0 Pass 0.0013 16 0 0 Pass 0.0013 15 0 0 Pass 0.0014 15 0 0 Pass 0.0014 14 0 0 Pass 0.0014 13 0 0 Pass 0.0014 13 0 0 Pass 0.0015 13 0 0 Pass 0.0015 13 0 0 Pass 0.0015 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0017 11 0 0 Pass 0.0017 11 0 0 Pass 0.0017 11 0 0 Pass 0.0018 11 0 0 Pass 0.0018 11 0 0 Pass 0.0018 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0021 10 0 0 Pass 0.0021 10 0 0 Pass 0.0021 9 0 0 Pass 0.0021 9 0 0 Pass 0.0022 8 0 0 Pass 0.0022 8 0 0 Pass 0.0022 8 0 0 Pass 0.0023 8 0 0 Pass 0.0023 8 0 0 Pass 0.0023 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 7 0 0 Pass 0.0026 7 0 0 Pass 0.0027 7 0 0 Pass 0.0027 7 0 0 Pass 0.0027 6 0 0 Pass 0.0028 6 0 0 Pass 0.0028 6 0 0 Pass 0.0028 6 0 0 Pass 0.0029 6 0 0 Pass 0.0029 6 0 0 Pass 0.0029 6 0 0 Pass 0.0029 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0031 5 0 0 Pass 0.0031 5 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 North Center Pervious POC N 52.61 N 99.92 Total Volume Infiltrated 52.61 0.00 0.00 99.92 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd 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 Â© by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. less than 4 inches SOUTH CENTER INFILTRATION AREA TRIBUTARY PAVEMENT AREA 6,181 SF = 0.14AC SOUTH CENTER INFILTRATION AREA 7,868SF = 88.7^2SF WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Arlington (South Center) Site Name: PUD Pole Yard Site Address: 59th Ave NE City : Arlington Report Date: 10/3/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.20 Version Date: 2016/02/25 Version : 4.2.12 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : PreDev South Center Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .32 Pervious Total 0.32 Impervious Land Use acre Impervious Total 0 Basin Total 0.32 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : South Center Pervious Bottom Length: 88.70 ft. Bottom Width: 88.70 ft. Trench bottom slope 1: 0 To 1 Total gravel area is Trench Left side slope 0: 0 To 1 7,868 square feet Trench right side slope 2: 0 To 1 Material thickness of first layer: 0.6666 Pour Space of material for first layer: 0.4 Material thickness of second layer: 1.5 Pour Space of material for second layer: 0.4 Material thickness of third layer: 0.3333 No backwater into treatment layer Pour Space of material for third layer: 0.4 above 4 inches of rock at base of facility Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 62.013 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 62.013 Percent Infiltrated: 100 Total Precip Applied to Facility: 37.219 Total Evap From Facility: 2.314 Discharge Structure Riser Height: 0.3333 ft. Precipitation applied to Riser Diameter: 24 in. facility 7,868 sf 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 0.180 0.000 0.000 0.000 0.0278 0.180 0.002 0.000 0.218 0.0556 0.180 0.004 0.000 0.218 0.0833 0.180 0.006 0.000 0.218 0.1111 0.180 0.008 0.000 0.218 0.1389 0.180 0.010 0.000 0.218 0.1667 0.180 0.012 0.000 0.218 0.1944 0.180 0.014 0.000 0.218 0.2222 0.180 0.016 0.000 0.218 0.2500 0.180 0.018 0.000 0.218 0.2778 0.180 0.020 0.000 0.218 0.3056 0.180 0.022 0.000 0.218 0.3333 0.180 0.024 0.000 0.218 0.3611 0.180 0.026 0.098 0.218 0.3889 0.180 0.028 0.278 0.218 0.4167 0.180 0.030 0.510 0.218 0.4444 0.180 0.032 0.785 0.218 0.4722 0.180 0.034 1.096 0.218 0.5000 0.180 0.036 1.438 0.218 0.5278 0.180 0.038 1.809 0.218 0.5556 0.180 0.040 2.205 0.218 0.5833 0.180 0.042 2.623 0.218 0.6111 0.180 0.044 3.060 0.218 0.6389 0.180 0.046 3.513 0.218 0.6667 0.180 0.048 3.979 0.218 0.6944 0.180 0.050 4.456 0.218 0.7222 0.180 0.052 4.940 0.218 0.7500 0.180 0.054 5.428 0.218 0.7778 0.180 0.056 5.917 0.218 0.8056 0.180 0.058 6.405 0.218 0.8333 0.180 0.060 6.888 0.218 0.8611 0.180 0.062 7.363 0.218 0.8889 0.180 0.064 7.827 0.218 0.9167 0.180 0.066 8.277 0.218 0.9444 0.180 0.068 8.712 0.218 0.9722 0.180 0.070 9.128 0.218 1.0000 0.180 0.072 9.523 0.218 1.0278 0.180 0.074 9.896 0.218 1.0556 0.180 0.076 10.24 0.218 1.0833 0.180 0.078 10.56 0.218 1.1111 0.180 0.080 10.86 0.218 1.1389 0.180 0.082 11.14 0.218 1.1667 0.180 0.084 11.38 0.218 1.1944 0.180 0.086 11.61 0.218 1.2222 0.180 0.088 11.81 0.218 1.2500 0.180 0.090 11.99 0.218 1.2778 0.180 0.092 12.16 0.218 1.3056 0.180 0.094 12.31 0.218 1.3333 0.180 0.096 12.59 0.218 1.3611 0.180 0.098 12.77 0.218 1.3889 0.180 0.100 12.94 0.218 1.4167 0.180 0.102 13.11 0.218 1.4444 0.180 0.104 13.28 0.218 1.4722 0.180 0.106 13.44 0.218 1.5000 0.180 0.108 13.60 0.218 1.5278 0.180 0.110 13.76 0.218 1.5556 0.180 0.112 13.92 0.218 1.5833 0.180 0.114 14.08 0.218 1.6111 0.180 0.116 14.24 0.218 1.6389 0.180 0.118 14.39 0.218 1.6667 0.180 0.120 14.54 0.218 1.6944 0.180 0.122 14.69 0.218 1.7222 0.180 0.124 14.84 0.218 1.7500 0.180 0.126 14.99 0.218 1.7778 0.180 0.128 15.14 0.218 1.8056 0.180 0.130 15.28 0.218 1.8333 0.180 0.132 15.43 0.218 1.8611 0.180 0.134 15.57 0.218 1.8889 0.180 0.136 15.71 0.218 1.9167 0.180 0.138 15.85 0.218 1.9444 0.180 0.140 15.99 0.218 1.9722 0.180 0.142 16.12 0.218 2.0000 0.180 0.144 16.26 0.218 2.0278 0.180 0.146 16.40 0.218 2.0556 0.180 0.148 16.53 0.218 2.0833 0.180 0.150 16.66 0.218 2.1111 0.180 0.152 16.79 0.218 2.1389 0.180 0.154 16.92 0.218 2.1667 0.180 0.156 17.05 0.218 2.1944 0.180 0.158 17.18 0.218 2.2222 0.180 0.160 17.31 0.218 2.2500 0.180 0.162 17.44 0.218 2.2778 0.180 0.164 17.56 0.218 2.3056 0.180 0.166 17.69 0.218 2.3333 0.180 0.168 17.81 0.218 2.3611 0.180 0.170 17.94 0.218 2.3889 0.180 0.172 18.06 0.218 2.4167 0.180 0.174 18.18 0.218 2.4444 0.180 0.176 18.30 0.218 2.4722 0.180 0.178 18.42 0.218 2.5000 0.180 0.183 18.54 0.218 ___________________________________________________________________ Name : Impervious Bypass: No pavement tributuary to Impervious Land Use acre gravel area ROADS FLAT LAT 0.14 ___________________________________________________________________ Element Flows To: Outlet 1 Outlet 2 South Center Pervious ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.32 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.14 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000367 5 year 0.000797 10 year 0.001278 25 year 0.002232 50 year 0.003298 100 year 0.004784 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.000 1950 0.001 0.000 1951 0.001 0.000 1952 0.000 0.000 1953 0.000 0.000 1954 0.002 0.000 1955 0.001 0.000 1956 0.000 0.000 1957 0.000 0.000 1958 0.000 0.000 1959 0.001 0.000 1960 0.000 0.000 1961 0.001 0.000 1962 0.000 0.000 1963 0.000 0.000 1964 0.001 0.000 1965 0.000 0.000 1966 0.000 0.000 1967 0.000 0.000 1968 0.000 0.000 1969 0.000 0.000 1970 0.000 0.000 1971 0.001 0.000 1972 0.000 0.000 1973 0.000 0.000 1974 0.001 0.000 1975 0.000 0.000 1976 0.001 0.000 1977 0.000 0.000 1978 0.000 0.000 1979 0.001 0.000 1980 0.000 0.000 1981 0.000 0.000 1982 0.000 0.000 1983 0.000 0.000 1984 0.000 0.000 1985 0.000 0.000 1986 0.002 0.000 1987 0.001 0.000 1988 0.000 0.000 1989 0.000 0.000 1990 0.000 0.000 1991 0.000 0.000 1992 0.000 0.000 1993 0.000 0.000 1994 0.000 0.000 1995 0.000 0.000 1996 0.003 0.000 1997 0.008 0.000 1998 0.000 0.000 1999 0.000 0.000 2000 0.000 0.000 2001 0.000 0.000 2002 0.000 0.000 2003 0.000 0.000 2004 0.000 0.000 2005 0.000 0.000 2006 0.009 0.000 2007 0.000 0.000 2008 0.000 0.000 2009 0.000 0.000 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0085 0.0000 2 0.0079 0.0000 3 0.0029 0.0000 4 0.0023 0.0000 5 0.0018 0.0000 6 0.0015 0.0000 7 0.0013 0.0000 8 0.0012 0.0000 9 0.0012 0.0000 10 0.0008 0.0000 11 0.0007 0.0000 12 0.0007 0.0000 13 0.0006 0.0000 14 0.0006 0.0000 15 0.0005 0.0000 16 0.0005 0.0000 17 0.0005 0.0000 18 0.0005 0.0000 19 0.0005 0.0000 20 0.0004 0.0000 21 0.0004 0.0000 22 0.0004 0.0000 23 0.0003 0.0000 24 0.0003 0.0000 25 0.0003 0.0000 26 0.0003 0.0000 27 0.0003 0.0000 28 0.0003 0.0000 29 0.0003 0.0000 30 0.0003 0.0000 31 0.0003 0.0000 32 0.0003 0.0000 33 0.0003 0.0000 34 0.0003 0.0000 35 0.0003 0.0000 36 0.0003 0.0000 37 0.0003 0.0000 38 0.0003 0.0000 39 0.0003 0.0000 40 0.0003 0.0000 41 0.0003 0.0000 42 0.0003 0.0000 43 0.0003 0.0000 44 0.0003 0.0000 45 0.0003 0.0000 46 0.0003 0.0000 47 0.0003 0.0000 48 0.0003 0.0000 49 0.0003 0.0000 50 0.0003 0.0000 51 0.0003 0.0000 52 0.0003 0.0000 53 0.0003 0.0000 54 0.0003 0.0000 55 0.0002 0.0000 56 0.0002 0.0000 57 0.0002 0.0000 58 0.0002 0.0000 59 0.0002 0.0000 60 0.0002 0.0000 61 0.0002 0.0000 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0002 2391 0 0 Pass 0.0002 1364 0 0 Pass 0.0002 450 0 0 Pass 0.0003 112 0 0 Pass 0.0003 103 0 0 Pass 0.0003 89 0 0 Pass 0.0004 77 0 0 Pass 0.0004 66 0 0 Pass 0.0004 61 0 0 Pass 0.0005 58 0 0 Pass 0.0005 54 0 0 Pass 0.0005 50 0 0 Pass 0.0006 49 0 0 Pass 0.0006 47 0 0 Pass 0.0006 43 0 0 Pass 0.0007 40 0 0 Pass 0.0007 36 0 0 Pass 0.0007 36 0 0 Pass 0.0007 32 0 0 Pass 0.0008 31 0 0 Pass 0.0008 31 0 0 Pass 0.0008 29 0 0 Pass 0.0009 29 0 0 Pass 0.0009 27 0 0 Pass 0.0009 26 0 0 Pass 0.0010 26 0 0 Pass 0.0010 26 0 0 Pass 0.0010 25 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0012 23 0 0 Pass 0.0012 23 0 0 Pass 0.0012 21 0 0 Pass 0.0013 19 0 0 Pass 0.0013 18 0 0 Pass 0.0013 17 0 0 Pass 0.0013 16 0 0 Pass 0.0014 16 0 0 Pass 0.0014 15 0 0 Pass 0.0014 15 0 0 Pass 0.0015 14 0 0 Pass 0.0015 13 0 0 Pass 0.0015 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0017 13 0 0 Pass 0.0017 13 0 0 Pass 0.0017 13 0 0 Pass 0.0018 13 0 0 Pass 0.0018 11 0 0 Pass 0.0018 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0021 11 0 0 Pass 0.0021 11 0 0 Pass 0.0021 11 0 0 Pass 0.0022 11 0 0 Pass 0.0022 11 0 0 Pass 0.0022 10 0 0 Pass 0.0023 9 0 0 Pass 0.0023 9 0 0 Pass 0.0023 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 8 0 0 Pass 0.0027 8 0 0 Pass 0.0027 8 0 0 Pass 0.0027 8 0 0 Pass 0.0028 8 0 0 Pass 0.0028 7 0 0 Pass 0.0028 7 0 0 Pass 0.0029 7 0 0 Pass 0.0029 7 0 0 Pass 0.0029 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0031 6 0 0 Pass 0.0031 6 0 0 Pass 0.0031 6 0 0 Pass 0.0032 6 0 0 Pass 0.0032 6 0 0 Pass 0.0032 6 0 0 Pass 0.0033 5 0 0 Pass 0.0033 5 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 South Center Pervious POC N 56.46 N 99.96 Total Volume Infiltrated 56.46 0.00 0.00 99.96 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd 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 Â© by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. less than 4 inches PERIMETER INFILTRATION AREA TRIBUTARY PAVEMENT AREA 11,063 SF = 0.25AC PERIMETER INFILTRATION AREA 31,223SF = 176.70^2SF WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Arlington (Perimeter) Site Name: PUD Pole Yard Site Address: 59th Ave NE City : Arlington Report Date: 10/3/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.20 Version Date: 2016/02/25 Version : 4.2.12 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : PreDev Perimeter Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .96 Pervious Total 0.96 Impervious Land Use acre Impervious Total 0 Basin Total 0.96 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : North Center Pervious Bottom Length: 176.70 ft. Bottom Width: 176.70 ft. Trench bottom slope 1: 0 To 1 Total gravel area is Trench Left side slope 0: 0 To 1 31,223 square feet Trench right side slope 2: 0 To 1 Material thickness of first layer: 0.66666 Pour Space of material for first layer: 0.4 Material thickness of second layer: 1.5 Pour Space of material for second layer: 0.4 No backwater into treatment layer Material thickness of third layer: 0.333 above 4 inches of rock at base of facility Pour Space of material for third layer: 0.4 Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 186.463 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 186.463 Percent Infiltrated: 100 Total Precip Applied to Facility: 145.611 Total Evap From Facility: 7.569 Discharge Structure Riser Height: 0.3333 ft. Precipitation applied to Riser Diameter: 24 in. facility 31,223 sf 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 0.716 0.000 0.000 0.000 0.0278 0.716 0.008 0.000 0.867 0.0556 0.716 0.015 0.000 0.867 0.0833 0.716 0.023 0.000 0.867 0.1111 0.716 0.031 0.000 0.867 0.1389 0.716 0.039 0.000 0.867 0.1667 0.716 0.047 0.000 0.867 0.1944 0.716 0.055 0.000 0.867 0.2222 0.716 0.063 0.000 0.867 0.2500 0.716 0.071 0.000 0.867 0.2778 0.716 0.079 0.000 0.867 0.3056 0.716 0.087 0.000 0.867 0.3333 0.716 0.095 0.000 0.867 0.3611 0.716 0.103 0.098 0.867 0.3889 0.716 0.111 0.278 0.867 0.4167 0.716 0.119 0.510 0.867 0.4444 0.716 0.127 0.785 0.867 0.4722 0.716 0.135 1.096 0.867 0.5000 0.716 0.143 1.438 0.867 0.5278 0.716 0.151 1.809 0.867 0.5556 0.716 0.159 2.205 0.867 0.5833 0.716 0.167 2.623 0.867 0.6111 0.716 0.175 3.060 0.867 0.6389 0.716 0.183 3.513 0.867 0.6667 0.716 0.191 3.979 0.867 0.6944 0.716 0.199 4.456 0.867 0.7222 0.716 0.207 4.940 0.867 0.7500 0.716 0.215 5.428 0.867 0.7778 0.716 0.223 5.917 0.867 0.8056 0.716 0.231 6.405 0.867 0.8333 0.716 0.238 6.888 0.867 0.8611 0.716 0.246 7.363 0.867 0.8889 0.716 0.254 7.827 0.867 0.9167 0.716 0.262 8.277 0.867 0.9444 0.716 0.270 8.712 0.867 0.9722 0.716 0.278 9.128 0.867 1.0000 0.716 0.286 9.523 0.867 1.0278 0.716 0.294 9.896 0.867 1.0556 0.716 0.302 10.24 0.867 1.0833 0.716 0.310 10.56 0.867 1.1111 0.716 0.318 10.86 0.867 1.1389 0.716 0.326 11.14 0.867 1.1667 0.716 0.334 11.38 0.867 1.1944 0.716 0.342 11.61 0.867 1.2222 0.716 0.350 11.81 0.867 1.2500 0.716 0.358 11.99 0.867 1.2778 0.716 0.366 12.16 0.867 1.3056 0.716 0.374 12.31 0.867 1.3333 0.716 0.382 12.59 0.867 1.3611 0.716 0.390 12.77 0.867 1.3889 0.716 0.398 12.94 0.867 1.4167 0.716 0.406 13.11 0.867 1.4444 0.716 0.414 13.28 0.867 1.4722 0.716 0.422 13.44 0.867 1.5000 0.716 0.430 13.60 0.867 1.5278 0.716 0.438 13.76 0.867 1.5556 0.716 0.446 13.92 0.867 1.5833 0.716 0.454 14.08 0.867 1.6111 0.716 0.461 14.24 0.867 1.6389 0.716 0.469 14.39 0.867 1.6667 0.716 0.477 14.54 0.867 1.6944 0.716 0.485 14.69 0.867 1.7222 0.716 0.493 14.84 0.867 1.7500 0.716 0.501 14.99 0.867 1.7778 0.716 0.509 15.14 0.867 1.8056 0.716 0.517 15.28 0.867 1.8333 0.716 0.525 15.43 0.867 1.8611 0.716 0.533 15.57 0.867 1.8889 0.716 0.541 15.71 0.867 1.9167 0.716 0.549 15.85 0.867 1.9444 0.716 0.557 15.99 0.867 1.9722 0.716 0.565 16.12 0.867 2.0000 0.716 0.573 16.26 0.867 2.0278 0.716 0.581 16.40 0.867 2.0556 0.716 0.589 16.53 0.867 2.0833 0.716 0.597 16.66 0.867 2.1111 0.716 0.605 16.79 0.867 2.1389 0.716 0.613 16.92 0.867 2.1667 0.716 0.621 17.05 0.867 2.1944 0.716 0.629 17.18 0.867 2.2222 0.716 0.637 17.31 0.867 2.2500 0.716 0.645 17.44 0.867 2.2778 0.716 0.653 17.56 0.867 2.3056 0.716 0.661 17.69 0.867 2.3333 0.716 0.669 17.81 0.867 2.3611 0.716 0.677 17.94 0.867 2.3889 0.716 0.684 18.06 0.867 2.4167 0.716 0.692 18.18 0.867 2.4444 0.716 0.700 18.30 0.867 2.4722 0.716 0.708 18.42 0.867 2.5000 0.716 0.728 18.54 0.867 ___________________________________________________________________ Name : Lateral I Basin 1 Bypass: No pavement tributuary to Impervious Land Use acre gravel area ROADS FLAT LAT 0.25 ___________________________________________________________________ Element Flows To: Outlet 1 Outlet 2 North Center Pervious ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.96 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.25 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.001102 5 year 0.00239 10 year 0.003834 25 year 0.006695 50 year 0.009894 100 year 0.014351 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.001 0.000 1950 0.002 0.000 1951 0.002 0.000 1952 0.001 0.000 1953 0.001 0.000 1954 0.005 0.000 1955 0.004 0.000 1956 0.001 0.000 1957 0.001 0.000 1958 0.001 0.000 1959 0.002 0.000 1960 0.001 0.000 1961 0.004 0.000 1962 0.001 0.000 1963 0.001 0.000 1964 0.003 0.000 1965 0.001 0.000 1966 0.001 0.000 1967 0.001 0.000 1968 0.001 0.000 1969 0.001 0.000 1970 0.001 0.000 1971 0.004 0.000 1972 0.001 0.000 1973 0.001 0.000 1974 0.002 0.000 1975 0.001 0.000 1976 0.002 0.000 1977 0.001 0.000 1978 0.001 0.000 1979 0.002 0.000 1980 0.001 0.000 1981 0.001 0.000 1982 0.001 0.000 1983 0.001 0.000 1984 0.001 0.000 1985 0.001 0.000 1986 0.007 0.000 1987 0.004 0.000 1988 0.001 0.000 1989 0.001 0.000 1990 0.001 0.000 1991 0.001 0.000 1992 0.001 0.000 1993 0.001 0.000 1994 0.001 0.000 1995 0.001 0.000 1996 0.009 0.000 1997 0.024 0.000 1998 0.001 0.000 1999 0.001 0.000 2000 0.001 0.000 2001 0.001 0.000 2002 0.001 0.000 2003 0.001 0.000 2004 0.001 0.000 2005 0.001 0.000 2006 0.026 0.000 2007 0.001 0.000 2008 0.001 0.000 2009 0.001 0.000 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0256 0.0000 2 0.0238 0.0000 3 0.0087 0.0000 4 0.0068 0.0000 5 0.0053 0.0000 6 0.0044 0.0000 7 0.0040 0.0000 8 0.0037 0.0000 9 0.0036 0.0000 10 0.0025 0.0000 11 0.0022 0.0000 12 0.0020 0.0000 13 0.0017 0.0000 14 0.0017 0.0000 15 0.0016 0.0000 16 0.0015 0.0000 17 0.0015 0.0000 18 0.0014 0.0000 19 0.0014 0.0000 20 0.0013 0.0000 21 0.0012 0.0000 22 0.0011 0.0000 23 0.0009 0.0000 24 0.0008 0.0000 25 0.0008 0.0000 26 0.0008 0.0000 27 0.0008 0.0000 28 0.0008 0.0000 29 0.0008 0.0000 30 0.0008 0.0000 31 0.0008 0.0000 32 0.0008 0.0000 33 0.0008 0.0000 34 0.0008 0.0000 35 0.0008 0.0000 36 0.0008 0.0000 37 0.0008 0.0000 38 0.0008 0.0000 39 0.0008 0.0000 40 0.0008 0.0000 41 0.0008 0.0000 42 0.0008 0.0000 43 0.0008 0.0000 44 0.0008 0.0000 45 0.0008 0.0000 46 0.0008 0.0000 47 0.0008 0.0000 48 0.0008 0.0000 49 0.0008 0.0000 50 0.0008 0.0000 51 0.0008 0.0000 52 0.0008 0.0000 53 0.0008 0.0000 54 0.0008 0.0000 55 0.0007 0.0000 56 0.0007 0.0000 57 0.0007 0.0000 58 0.0007 0.0000 59 0.0007 0.0000 60 0.0007 0.0000 61 0.0005 0.0000 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0006 2355 0 0 Pass 0.0006 1329 0 0 Pass 0.0007 438 0 0 Pass 0.0008 112 0 0 Pass 0.0009 103 0 0 Pass 0.0010 89 0 0 Pass 0.0011 77 0 0 Pass 0.0012 66 0 0 Pass 0.0013 61 0 0 Pass 0.0014 58 0 0 Pass 0.0015 54 0 0 Pass 0.0016 50 0 0 Pass 0.0017 49 0 0 Pass 0.0018 47 0 0 Pass 0.0019 43 0 0 Pass 0.0020 40 0 0 Pass 0.0021 36 0 0 Pass 0.0022 36 0 0 Pass 0.0022 32 0 0 Pass 0.0023 31 0 0 Pass 0.0024 31 0 0 Pass 0.0025 29 0 0 Pass 0.0026 29 0 0 Pass 0.0027 27 0 0 Pass 0.0028 26 0 0 Pass 0.0029 26 0 0 Pass 0.0030 26 0 0 Pass 0.0031 25 0 0 Pass 0.0032 23 0 0 Pass 0.0033 23 0 0 Pass 0.0034 23 0 0 Pass 0.0035 23 0 0 Pass 0.0036 23 0 0 Pass 0.0037 21 0 0 Pass 0.0038 19 0 0 Pass 0.0039 18 0 0 Pass 0.0039 17 0 0 Pass 0.0040 16 0 0 Pass 0.0041 16 0 0 Pass 0.0042 15 0 0 Pass 0.0043 15 0 0 Pass 0.0044 14 0 0 Pass 0.0045 13 0 0 Pass 0.0046 13 0 0 Pass 0.0047 13 0 0 Pass 0.0048 13 0 0 Pass 0.0049 13 0 0 Pass 0.0050 13 0 0 Pass 0.0051 13 0 0 Pass 0.0052 13 0 0 Pass 0.0053 13 0 0 Pass 0.0054 11 0 0 Pass 0.0055 11 0 0 Pass 0.0056 11 0 0 Pass 0.0056 11 0 0 Pass 0.0057 11 0 0 Pass 0.0058 11 0 0 Pass 0.0059 11 0 0 Pass 0.0060 11 0 0 Pass 0.0061 11 0 0 Pass 0.0062 11 0 0 Pass 0.0063 11 0 0 Pass 0.0064 11 0 0 Pass 0.0065 11 0 0 Pass 0.0066 10 0 0 Pass 0.0067 10 0 0 Pass 0.0068 9 0 0 Pass 0.0069 9 0 0 Pass 0.0070 8 0 0 Pass 0.0071 8 0 0 Pass 0.0072 8 0 0 Pass 0.0073 8 0 0 Pass 0.0073 8 0 0 Pass 0.0074 8 0 0 Pass 0.0075 8 0 0 Pass 0.0076 8 0 0 Pass 0.0077 8 0 0 Pass 0.0078 8 0 0 Pass 0.0079 8 0 0 Pass 0.0080 8 0 0 Pass 0.0081 8 0 0 Pass 0.0082 8 0 0 Pass 0.0083 8 0 0 Pass 0.0084 7 0 0 Pass 0.0085 7 0 0 Pass 0.0086 7 0 0 Pass 0.0087 7 0 0 Pass 0.0088 6 0 0 Pass 0.0089 6 0 0 Pass 0.0090 6 0 0 Pass 0.0090 6 0 0 Pass 0.0091 6 0 0 Pass 0.0092 6 0 0 Pass 0.0093 6 0 0 Pass 0.0094 6 0 0 Pass 0.0095 6 0 0 Pass 0.0096 6 0 0 Pass 0.0097 6 0 0 Pass 0.0098 5 0 0 Pass 0.0099 5 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 North Center Pervious POC N 169.70 N 99.99 Total Volume Infiltrated 169.70 0.00 0.00 99.99 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd 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 Â© by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. less than 4 inches Appendix C â€“ Runoff Treatment Stormwater Site Plan Appendix C Arlington Electrical Equipment &Pole Storage Yard July, 2016 8410 154th Avenue NE Redmond, Washington 98052 425.861.6000 August 16, 2016 Snohomish County PUD No. 1 Facilities Department 2323 California Street P.O. Box 1107 Everett, Washington 98206 Attention: Ben Davis, PE Subject: Custom Bioretention Soil Mix Proposed Pole Storage Yard Arlington Site Development Arlington, Washington File No. 0482-051-03 INTRODUCTION This letter contains the laboratory testing results and recommendations for a custom bioretention soil mix for use in the design and construction of the proposed Pole Storage Yard at the Districtâ€™s Arlington Site located between 172nd Street NE and 180th Street NE off of 59th Avenue NE in Arlington, Washington. GeoEngineers previously prepared a geotechnical report for the project titled, â€œGeotechnical Engineering Services, Proposed Pole Storage Yard, Arlington Site Development, Arlington, Washington,â€ dated May 4, 2016. Project Description We understand that a portion of the Arlington property is being developed for a Pole Storage Yard to store treated poles and transformers. Development of the pole storage yard will include constructing gravel laydown areas, asphalt paved access roads and transformer storage areas, and installation of a water line. We understand that the native soils do not meet the minimum requirements for treatment of stormwater infiltration at the site. In order to meet storm water guidelines, the District is looking at using an imported amended soil mix that will be placed below the pole storage yard surfacing gravel to improve treatment of stormwater infiltration. The amended material will need to support occasional truck traffic loads, therefore the Default Bioretention Soil Media (BSM) standard 60/40 compost soil mix (by volume) from the 2014 Stormwater Management Manual for Western Washington (SWMMWW) will not be sufficient from a structural support standpoint. Snohomish County PUD No. 1 | August 16, 2016 Page 2 Purpose and Scope The purpose of our engineering services is to develop a custom bioretention soil using a compost and gravel borrow mixture which will: (1) meet the 2014 SWMMWW requirements for a custom bioretention soil mix and (2) provide support for occasional truck traffic. CUSTOM BIORETENTION SOIL MIX REQUIREMENTS We understand that the 2014 SWMMWW allows for development of a custom bioretention soil mix. The SWMMWW lists the following criteria for a custom soil mix: â– Cation-exchange capacity (CEC) â‰¥ 5 milliequivalents/100 grams of dry soil; USEPA 9081. â– pH between 5.5 and 7.0. â– 5 to 8 percent organic matter content (by weight) before and after the saturated hydraulic conductivity test (ASTM D 2974). â– 2 to 5 percent fines passing the U.S. Standard No. 200 sieve â– Measured (initial) saturated hydraulic conductivity of less than 12 inches per hour; ASTM D 2434 (constant head) at 85 percent and 90 percent compaction (ASTM D 1557) as modified by Appendix V-B of the SWMMWW. â– Design (long-term) saturated hydraulic conductivity of more than 1 inch per hour. â– Compost to meet requirements of Volume V of the SWMMWW. SAMPLES FOR TESTING Gravel borrow and compost samples were collected from Lenz Enterprises, Inc. on June 15, 2016. Grain size analysis test results for the gravel borrow are presented in Appendix A. The borrow sample material meets the Washington State Department of Transportation (WSDOT) requirements for gravel borrow and is classified as a poorly graded sand with gravel with 4 percent passing the 200 sieve. The technical data sheet for the compost material that we received is presented in Appendix A (Figure A-1). File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 3 LABORATORY TESTING CEC Testing Cation Exchange Capacity (CEC) testing was performed following USEPA 9081 on a 5, 10, 15 and 20 percent compost to gravel borrow mix. The CEC test results are presented in Appendix A and are shown on the plot below. 10 9 8 7 6 5 4 3 CEC (meq/100grm) 2 1 0 0 5 10 15 20 25 Percent Compost by Weight pH Testing pH testing was performed on a 5, 10, 15 and 20 percent compost to gravel borrow mix. The pH test results are shown on the plot below. pH tests were also performed on the gravel borrow (pH = 6.1) and the compost (pH = 8.2) for baseline purposes. 10 9 8 7 6 pH5 4 3 2 1 0 0 5 10 15 20 25 Percent Compost by Weight File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 4 Organic Content Testing Organic content testing was performed following ASTM D 2974 on a 5, 10, 15 and 20 percent compost to gravel borrow mix prior to conducting the saturated hydraulic conductivity tests. One organic content test was performed on the 15 percent compost to gravel borrow mix following the saturated hydraulic conductivity test. The organic content test results are shown on the plot below. 10 9 8 7 6 5 4 3 2 Organic Content (percent)1 0 0 5 10 15 20 25 Percent Compost by Weight Before Hydraulic Conductivity Test After Hydraulic Conductivity Test Grain Size Analysis Grain size analysis testing was performed following ASTM D 6913 on the gravel borrow sample, the 10, 15 and 20 percent compost to gravel borrow mix. The grain size analysis test results are presented in Appendix A (Figure A-2). Proctor Testing Laboratory compaction testing was performed following ASTM D 1157 on the 10, 15 and 20 percent compost to gravel borrow mix designs. The laboratory compaction test results are presented in Appendix A (Figures A-3 through A-5) and the measured maximum dry density (MDD) test results are shown on the plot below. 128 126 124 122 120 118 116 114 112 110 108 Maximum Dry Density (pcf) 106 0 5 10 15 20 25 Percent Compost by Weight Uncorrected With Rock Correction File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 5 Saturated Hydraulic Conductivity Testing Saturated hydraulic conductivity testing was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 SWMMWW at 85 percent compaction (ASTM D 1557). The tests were completed on samples compacted at 85 and 90 percent of the MDD, respectively. The measured (initial) saturated hydraulic conductivity test results are presented in Appendix A (Figures A-6 through A-8) and are summarized on the plot below. 25 85% Compaction 20 90% Compaction 15 10 5 Measured (initial) saturated hydraulic conductivity (in/hour) 0 0 5 10 15 20 25 Percent Compost by Weight The 2014 SWMMWW recommends a factor of safety of 4.0 for the design hydraulic conductivity value. The design (long-term) saturated hydraulic conductivity values with an applied safety factor of 4.0 is shown in the plot below for the samples compacted at 85 and 90 percent of the MDD. 7 6 85% Compaction 90% Compaction 5 4 -term) saturated 3 2 1 Design (long hydraulic conductivity (in/hour) 0 0 5 10 15 20 25 Percent Compost by Weight CONCLUSIONS AND RECOMMENDATIONS Based on the results of the laboratory testing, the 15 percent compost to gravel borrow mix meets the requirements of the 2014 SWMMWW Design Criteria for Custom Bioretention Soil Mixes, with the exception of the pH values, which were slightly higher than the 7.0 maximum requirement. The pH of the tested File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 6 compost sample was 8.2. For the project specifications, we recommend compost with a pH between 5 and 7 be used for the bioretention soil mix in order to meet the SWMMWW design criteria. We recommend that the project specifications require gravel borrow be amended with 15 percent compost by weight for the custom bioretention soil mix below the gravel surfaced Pole Storage Yard. The gravel borrow should meet the requirements of section 9-03.14(1) of the 2016 WSDOT Standard Specifications. The compost should meet the requirements of the 2014 SWMMWW for bioretention. The materials should be adequately mixed to provide a uniform blended soil. The project specifications should require the contractor submit samples of their proposed custom bioretention soil mix for testing and verification purposes. GeoEngineers should test the submitted samples to confirm that the requirements of 2014 SWMMWW are satisfied (BMP T7.30, Design Criteria for Custom Bioretention Soil Mixes). A minimum 18-inch layer of the custom bioretention soil mix should be placed and compacted in areas designated for stormwater treatment. We recommend the bioretention soil mix be compacted in maximum 12 inch loose lifts to at least 85 percent of the MDD (corrected for gravel content) as determined by ASTM D 1557. This compaction effort is less than the standard of practice for support of traffic, therefore, periodic maintenance may be needed to repair rutting within the gravel surfacing if occasional vehicles are routed over these unpaved areas. The bioretention soil mix should not be placed below the asphalt or concrete paved areas of the site. In our opinion, a geotextile separation fabric is not needed above or below the bioretention gravel borrow mix, provided the bioretention soil is prepared as described above. The subgrade conditions and gravel surfacing recommendations provided in our May 4, 2016 geotechnical report should be followed. Although our proposed bioretention soil mix satisfies the 2014 SWMMWW design criteria for stormwater treatment, the structural capacity of the mix is limited because of the organic content and compaction criteria, and is not intended for support of significant equipment traffic. LIMITATIONS We have prepared this report for Snohomish County PUD No. 1. Copies of this report may be distributed to authorized agents and regulatory agencies as may be required for the project. Our evaluation pertains only to the physical properties of soil mechanics and hydrogeology as it pertains to the requirements of the 2014 SWMMWW design criteria. Chemical and treatment efficacy of the bioretention soil mix was not included in our scope of services. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. The conclusions, recommendations, and opinions presented in this report are based on our professional knowledge, judgment, laboratory test results, and experience. No warranty or other conditions, express or implied, should be understood. Any electronic form, facsimile or hard copy of the original document (email, text, table and/or figure), if provided, and any attachments should be considered a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record. File No. 0000-001-00 File No. 0482-051-03 APPENDIX A Laboratory Test Results 0482-051-03 Date Exported: 06/24/16 U.S. STANDARD SIEVE SIZE 3â€ 1.5â€ 3/4â€ 3/8â€ #4 #10 #20 #40 #60 #100 #200 100 90 80 70 60 PERCENT PASSING BY WEIGHT 50 40 30 20 10 0 Proposed Pole Storage Yard 1000 100 10 1 0.1 0.01 0.001 Sieve Analysis Results GRAIN SIZE IN MILLIMETERS Arlington, WA GRAVEL SAND COBBLES SILT OR CLAY COARSE FINE COARSE MEDIUM FINE Depth Moisture Symbol Sample (feet) (%) Soil Description No Compost N/A 5.4 Poorly graded sand with gravel (SP) Figure A 10% Compost N/A 8.0 Poorly graded sand with gravel and organic matter (SP) 15% Compost N/A 8.2 Poorly graded sand with silt and gravel and organic matter (SP-SM) 20% Compost N/A 12.1 Poorly graded sand with gravel and organic matter (SP) -2 Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they were performed,andshouldnotbe interpreted as representativeofanyothersamples obtained atother times,depthsorlocations,orgenerated by separate operationsorprocesses. Thegrainsizeanalysis results were obtained in general accordancewithASTMD6913. MOISTURE CONTENT (%) 0 5 10 15 20 25 30 140 135 130 125 (pcf) 120 DRY DENSITY 115 100% Saturation 110 (Gs=2.65) 105 100 Optimum Maximum Depth Moisture Dry Density Symbol Sample (feet) Soil Description (%) (pcf) Corrected 10% 9.9 127.1 N/A 10 Percent Compost/Gravel Borrow Mix Uncorrected Compost 13.5 116.0 Note: This report may not be reproduced, except in full, without written approval Compaction Test Results of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they were performed, and should not be interpreted as 10% Compost Mix representative of any other samples obtained at other times, depths or locations,orgenerated by separate operationsorprocesses. Proposed Pole Storage Yard The Proctor results were obtained in general accordance with Exported: 06/27/16 ASTMD1557. Arlington, WA Date -03 051 Figure A-3 0482- MOISTURE CONTENT (%) 0 5 10 15 20 25 30 140 135 130 125 (pcf) 120 DRY DENSITY 115 100% Saturation 110 (Gs=2.65) 105 100 Optimum Maximum Depth Moisture Dry Density Symbol Sample (feet) Soil Description (%) (pcf) Corrected 15% 9.1 126.0 N/A 15 Percent Compost/Gravel Borrow Mix Uncorrected Compost 12.5 114.0 Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific Compaction Test Results sample on which they were performed, and should not be interpreted as 15% Compost Mix representative of any other samples obtained at other times, depths or locations,orgenerated by separate operationsorprocesses. Proposed Pole Storage Yard The Proctor results were obtained in general accordance with Exported: 06/30/16 ASTMD1557. Arlington, WA Date -03 051 Figure A-4 0482- MOISTURE CONTENT (%) 0 5 10 15 20 25 125 120 100% 115 Saturation (Gs=2.65) (pcf) 110 DRY DENSITY 105 100 95 Optimum Maximum Depth Moisture Dry Density Symbol Sample (feet) Soil Description (%) (pcf) Corrected 20% 10.6 120.0 Grab Poorly graded sand with gravel and organic matter (SP) Uncorrected Compost 13.7 109.6 Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific Compaction Test Results sample on which they were performed, and should not be interpreted as 20% Compost Mix representative of any other samples obtained at other times, depths or locations,orgenerated by separate operationsorprocesses. Proposed Pole Storage Yard The Proctor results were obtained in general accordance with Exported: 07/08/16 ASTMD1557. Arlington, WA Date -03 051 Figure A-5 0482- Boring #: N/A Sample #: 10% Mix Depth: N/A Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 116.0 Optimum Moisture Content (%) 13.5 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 85.0 Sample Prepared Moisture Content (%) 13.5 Sample length (in): 8.00 (cm): 20.32 (L) Remolded Compaction (%) 85.3 Sample volume (in3): 226.19 (cm3): 3707.33 Sample Back Calculated After Test 86.4 Compaction (%) Sample volume (ft3): 0.1309 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 80.00 81.00 1.00 15.2 50.0 233 1.18E-03 0.066 1.79E-02 22.0 0.9547 1.70E-0224.1 2 80.00 81.00 1.00 15.2 50.0 234 1.17E-03 0.066 1.78E-02 22.0 0.9547 1.70E-0224.0 3 80.00 81.00 1.00 15.2 50.0 232 1.18E-03 0.066 1.80E-02 22.0 0.9547 1.71E-0224.2 4 80.00 81.00 1.00 15.2 50.0 233 1.18E-03 0.066 1.79E-02 22.0 0.9547 1.70E-0224.1 avg 1.79E-02 1.70E-02 24.1 1 80.00 81.00 1.00 15.2 100.0 469 1.17E-03 0.066 1.78E-02 22.0 0.9547 1.69E-02 24.0 2 80.00 81.00 1.00 15.2 100.0 473 1.16E-03 0.066 1.76E-02 22.0 0.9547 1.68E-02 23.8 3 80.00 81.00 1.00 15.2 100.0 473 1.16E-03 0.066 1.76E-02 22.0 0.9547 1.68E-02 23.8 4 80.00 81.00 1.00 15.2 100.0 471 1.16E-03 0.066 1.77E-02 22.0 0.9547 1.69E-02 23.9 5 80.00 81.00 1.00 15.2 100.0 473 1.16E-03 0.066 1.76E-02 22.1 0.9524 1.67E-02 23.7 6 80.00 81.00 1.00 15.2 250.0 1207 1.14E-03 0.066 1.73E-02 22.1 0.9524 1.64E-02 23.2 avg 1.76E-02 1.67E-02 23.7 Total avg 1.77E-02 1.69E-02 23.9 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 10% Compost Mix at 85% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-6 Manual for Western Washington (SWMMWW). Boring #: 10% Compost Sample #: 10% Mix (2) Depth: Grab Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 116.0 Sample area (in2): 28.274 (cm2): 182.43 (A) Optimum Moisture Content (%) 13.5 Target Relative Density (%) 90.0 Sample length (in): 9.00 (cm): 22.86 (L) Sample Prepared Moisture Content (%) 13.5 3 3 Remolded Compaction (%) 90.3 Sample volume (in): 254.47 (cm ): 4170.75 Sample Back Calculated After Test 90 Sample volume (ft3): 0.1473 Compaction (%) Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 79.50 81.80 2.30 15.2 10.0 117 4.69E-04 0.151 3.10E-03 19.4 1.0169 3.14E-034.5 2 79.50 81.80 2.30 15.2 10.0 121 4.53E-04 0.151 2.99E-03 19.4 1.0169 3.04E-034.3 3 79.50 81.80 2.30 15.2 10.0 119 4.61E-04 0.151 3.04E-03 19.4 1.0169 3.09E-034.4 4 79.50 81.80 2.30 15.2 10.0 112 4.89E-04 0.151 3.23E-03 19.4 1.0169 3.28E-034.7 5 79.50 81.80 2.30 15.2 20.0 217 5.05E-04 0.151 3.34E-03 19.4 1.0169 3.39E-034.8 6 79.50 81.80 2.30 15.2 20.0 210 5.22E-04 0.151 3.45E-03 19.5 1.0144 3.49E-035.0 avg 3.19E-03 3.24E-03 4.6 7 79.50 81.80 2.30 15.2 20.0 205 5.35E-04 0.151 3.53E-03 19.5 1.0144 3.58E-035.1 8 79.50 81.80 2.30 15.2 20.0 214 5.12E-04 0.151 3.39E-03 19.5 1.0144 3.43E-034.9 9 79.50 81.80 2.30 15.2 20.0 211 5.20E-04 0.151 3.43E-03 19.5 1.0144 3.48E-034.9 10 79.50 81.80 2.30 15.2 40.0 436 5.03E-04 0.151 3.32E-03 19.4 1.0169 3.37E-034.8 11 79.50 81.80 2.30 15.2 40.0 449 4.88E-04 0.151 3.23E-03 19.4 1.0169 3.28E-034.6 12 79.50 81.80 2.30 15.2 40.0 449 4.88E-04 0.151 3.23E-03 19.4 1.0169 3.28E-034.6 13 79.50 81.80 2.30 15.2 40.0 455 4.82E-04 0.151 3.18E-03 19.4 1.0169 3.23E-034.6 avg 3.33E-03 3.37E-03 4.8 14 79.50 81.80 2.30 15.2 40.0 478 4.59E-04 0.151 3.03E-03 19.3 1.0195 3.08E-034.4 15 79.50 81.80 2.30 15.2 40.0 469 4.68E-04 0.151 3.09E-03 19.2 1.0220 3.15E-034.5 16 79.50 81.80 2.30 15.2 40.0 479 4.58E-04 0.151 3.03E-03 19.2 1.0220 3.09E-034.4 avg 3.05E-03 3.11E-03 4.4 Total avg 3.19E-03 3.24E-03 4.6 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 10% Compost Mix at 90% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-7 Manual for Western Washington (SWMMWW). Constant Head Hydraulic Conductivity Test Project: Arlington Pole Storage Yard Date: 6/28/16 Project #: 0482-051-03 Tested by: S. Swenson Boring #: N/A Sample #: 15% Mix Depth: N/A Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 114.0 Optimum Moisture Content (%) 12.5 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 85.0 Sample Prepared Moisture Content (%) 13.0 Sample length (in): 9.00 (cm): 22.86 (L) Remolded Compaction (%) 84.5 Sample volume (in3): 254.47 (cm3): 4170.75 Sample Back Calculated After Test 91.2 Compaction (%) Sample volume (ft3): 0.1473 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 80.60 81.60 1.00 15.2 10.0 212 2.59E-04 0.066 3.93E-03 20.7 0.9850 3.86E-035.5 2 80.60 81.60 1.00 15.2 10.0 215 2.55E-04 0.066 3.88E-03 20.7 0.9850 3.81E-035.4 3 80.60 81.60 1.00 15.2 10.0 219 2.50E-04 0.066 3.80E-03 20.7 0.9850 3.74E-035.3 4 80.60 81.60 1.00 15.2 10.0 210 2.61E-04 0.066 3.97E-03 20.7 0.9850 3.90E-035.5 5 80.60 81.60 1.00 15.2 10.0 209 2.62E-04 0.066 3.99E-03 20.7 0.9850 3.92E-035.6 6 80.60 81.60 1.00 15.2 10.0 209 2.62E-04 0.066 3.99E-03 21.1 0.9755 3.88E-035.5 7 80.60 81.60 1.00 15.2 10.0 215 2.55E-04 0.066 3.88E-03 21.2 0.9732 3.76E-035.3 avg 3.92E-03 3.84E-03 5.4 1 80.60 81.60 1.00 15.2 20.0 421 2.60E-04 0.066 3.96E-03 21.0 0.9779 3.86E-035.5 2 80.60 81.60 1.00 15.2 20.0 401 2.73E-04 0.066 4.16E-03 20.7 0.9850 4.09E-035.8 3 80.60 81.60 1.00 15.2 20.0 440 2.49E-04 0.066 3.79E-03 20.7 0.9850 3.72E-035.3 4 80.60 81.60 1.00 15.2 20.0 423 2.59E-04 0.066 3.94E-03 21.0 0.9779 3.84E-035.4 avg 3.96E-03 3.88E-03 5.5 Total avg 3.94E-03 3.86E-03 5.5 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 15% Compost Mix at 85% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-8 Manual for Western Washington (SWMMWW). Boring #: Sample #: 15% Mix Depth: Grab Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 114.0 Optimum Moisture Content (%) 12.5 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 90.0 Sample Prepared Moisture Content (%) 12.5 Sample length (in): 9.00 (cm): 22.86 (L) Remolded Compaction (%) 90 Sample volume (in3): 254.47 (cm3): 4170.75 Sample Back Calculated After Test 90.2 Compaction (%) Sample volume (ft3): 0.1473 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 80.20 81.90 1.70 15.2 10.0 393 1.39E-04 0.112 1.25E-03 19.3 1.0195 1.27E-031.8 2 80.20 81.90 1.70 15.2 10.0 408 1.34E-04 0.112 1.20E-03 19.2 1.0220 1.23E-031.7 3 80.20 81.90 1.70 15.2 10.0 393 1.39E-04 0.112 1.25E-03 19.2 1.0220 1.27E-031.8 4 80.20 81.90 1.70 15.2 10.0 374 1.47E-04 0.112 1.31E-03 19.2 1.0220 1.34E-031.9 5 80.20 81.90 1.70 15.2 10.0 382 1.43E-04 0.112 1.28E-03 19.2 1.0220 1.31E-031.9 6 80.20 81.90 1.70 15.2 10.0 380 1.44E-04 0.112 1.29E-03 19.2 1.0220 1.32E-031.9 7 80.20 81.90 1.70 15.2 10.0 374 1.47E-04 0.112 1.31E-03 19.2 1.0220 1.34E-031.9 8 80.20 81.90 1.70 15.2 10.0 372 1.47E-04 0.112 1.32E-03 19.2 1.0220 1.34E-031.9 9 80.20 81.90 1.70 15.2 10.0 377 1.45E-04 0.112 1.30E-03 19.2 1.0220 1.33E-031.9 10 80.20 81.90 1.70 15.2 10.0 367 1.49E-04 0.112 1.34E-03 19.2 1.0220 1.36E-031.9 11 80.20 81.90 1.70 15.2 10.0 369 1.49E-04 0.112 1.33E-03 19.2 1.0220 1.35E-031.9 12 80.20 81.90 1.70 15.2 10.0 371 1.48E-04 0.112 1.32E-03 19.2 1.0220 1.35E-031.9 avg 1.29E-03 1.32E-03 1.9 1 80.20 81.90 1.70 15.2 67.0 2442 1.50E-04 0.112 1.34E-03 21.0 0.9779 1.31E-03 1.9 2 80.20 81.90 1.70 15.2 114.0 4029 1.55E-04 0.112 1.39E-03 20.7 0.9850 1.36E-03 1.9 avg 1.37E-03 1.34E-03 1.9 Total avg 1.33E-03 1.33E-03 1.9 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 15% Compost Mix at 90% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-9 Manual for Western Washington (SWMMWW). Constant Head Permeability Test data Project: Arlington Pole Storage Yard Date: 6/28/16 Project #: 0482-051-03 Tested by: S. Swenson Boring #: N/A Sample #: 20% Mix Depth: N/A Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 109.6 Optimum Moisture Content (%) 13.7 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 85.0 Sample Prepared Moisture Content (%) 13.7 Sample length (in): 9.00 (cm): 22.86 (L) Remolded Compaction (%) 84.7 Sample volume (in3): 254.47 (cm3): 4170.75 Sample Back Calculated After Test 85.4 Compaction (%) Sample volume (ft3): 0.1473 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 79.90 81.90 2.00 15.2 5.0 176 1.56E-04 0.132 1.18E-03 20.8 0.9826 1.16E-03 1.6 2 79.90 81.90 2.00 15.2 5.0 185 1.48E-04 0.132 1.13E-03 20.9 0.9803 1.10E-03 1.6 3 79.90 81.90 2.00 15.2 5.0 158 1.73E-04 0.132 1.32E-03 20.8 0.9826 1.29E-03 1.8 4 79.90 81.90 2.00 15.2 5.0 154 1.78E-04 0.132 1.35E-03 20.9 0.9803 1.32E-03 1.9 5 79.90 81.90 2.00 15.2 5.0 153 1.79E-04 0.132 1.36E-03 20.9 0.9803 1.33E-03 1.9 avg 1.26E-03 1.24E-03 1.8 1 79.90 81.90 2.00 15.2 10.0 350 1.57E-04 0.132 1.19E-03 21.0 0.9779 1.16E-031.6 2 79.90 81.90 2.00 15.2 10.0 337 1.63E-04 0.132 1.24E-03 20.9 0.9803 1.21E-031.7 3 79.90 81.90 2.00 15.2 10.0 338 1.62E-04 0.132 1.23E-03 21.1 0.9755 1.20E-031.7 4 79.90 81.90 2.00 15.2 10.0 342 1.60E-04 0.132 1.22E-03 21.0 0.9779 1.19E-031.7 5 79.90 81.90 2.00 15.2 10.0 340 1.61E-04 0.132 1.23E-03 21.1 0.9755 1.19E-031.7 6 79.90 81.90 2.00 15.2 10.0 335 1.64E-04 0.132 1.24E-03 21.1 0.9755 1.21E-031.7 7 79.90 81.90 2.00 15.2 10.0 337 1.63E-04 0.132 1.24E-03 21.1 0.9755 1.20E-031.7 8 79.90 81.90 2.00 15.2 10.0 341 1.61E-04 0.132 1.22E-03 21.1 0.9755 1.19E-031.7 9 79.90 81.90 2.00 15.2 10.0 336 1.63E-04 0.132 1.24E-03 21.2 0.9732 1.20E-031.7 10 79.90 81.90 2.00 15.2 10.0 339 1.62E-04 0.132 1.23E-03 21.2 0.9732 1.19E-031.7 avg 1.23E-03 1.20E-03 1.7 Total avg 1.25E-03 1.22E-03 1.7 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 20% Compost Mix at 85% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-10 Manual for Western Washington (SWMMWW). Appendix D â€“ Well Head Protection Zones Stormwater Site Plan Appendix D Arlington Electrical Equipment &Pole Storage Yard July, 2016 Haller Park Wellfield 4 3 2 1 6 9 10 11 12 7 16 15 14 13 18 Airport Well Project Site 21 22 23 24 19 Area of project site being developed. 28 27 26 25 30 33 34 35 36 31 FIGURE 1 Wells 1-Year-Buffer Wellhead Protection Zone 5-Year 6-Month 5-Year-Buffer WELLHEAD PROTECTION ZONES 6-Month-Buffer 10-Year 1-Year 10-Year-Buffer CITY OF ARLINGTON Feet 0 2,000 Appendix E â€“ Soil Map Stormwater Site Plan Appendix E Arlington Electrical Equipment &Pole Storage Yard July, 2016 Hydrologic Soil Groupâ€”Snohomish County Area, Washington (Arlington Temporary Storage Yard) 122Â° 9' 12'' 122Â° 8' 19'' 563000 563100 563200 563300 563400 563500 563600 563700 563800 563900 564000 48Â° 9' 35'' 48Â° 9' 35'' 5334400 5334400 180th St 59th Dr Bovee Ln 5334300 5334300 Upland Dr 72 5334200 5334200 74 18 5334100 Hillside Ct 5334100 30 39 59th Ave 5334000 5334000 5333900 5333900 67th Ave Highland View Dr 5333800 5333800 5333700 5333700 48Â° 9' 11'' 48Â° 9' 11'' 563000 563100 563200 563300 563400 563500 563600 563700 563800 563900 564000 Map Scale: 1:5,280 if printed on A size (8.5" x 11") sheet. Meters 122Â° 9' 13'' 0 50 100 200 300 122Â° 8' 19'' Feet 0 250 500 1,000 1,500 Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 1 of 4 Hydrologic Soil Groupâ€“Snohomish County Area, Washington (Arlington Temporary Storage Yard) MAP LEGEND MAP INFORMATION Area of Interest (AOI) Map Scale: 1:5,280 if printed on A size (8.5" Ã— 11") sheet. Area of Interest (AOI) The soil surveys that comprise your AOI were mapped at 1:24,000. Soils Soil Map Units Warning: Soil Map may not be valid at this scale. Soil Ratings Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line A placement. The maps do not show the small areas of contrasting A/D soils that could have been shown at a more detailed scale. B Please rely on the bar scale on each map sheet for accurate map B/D measurements. C Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov C/D Coordinate System: UTM Zone 10N NAD83 D This product is generated from the USDA-NRCS certified data as of Not rated or not available the version date(s) listed below. Political Features Soil Survey Area: Snohomish County Area, Washington Cities Survey Area Data: Version 7, Jun 29, 2012 Water Features Date(s) aerial images were photographed: 7/24/2006 Streams and Canals The orthophoto or other base map on which the soil lines were Transportation compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting Rails of map unit boundaries may be evident. Interstate Highways US Routes Major Roads Local Roads Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 2 of 4 Hydrologic Soil Groupâ€“Snohomish County Area, Washington Arlington Temporary Storage Yard Hydrologic Soil Group Hydrologic Soil Groupâ€” Summary by Map Unit â€” Snohomish County Area, Washington (WA661) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 18 Everett gravelly sandy loam, 8 A 5.4 6.8% to 15 percent slopes 30 Lynnwood loamy sand, 0 to 3 A 61.2 76.7% percent slopes 39 Norma loam B/D 12.5 15.7% 72 Tokul gravelly loam, 0 to 8 C 0.3 0.3% percent slopes 74 Tokul gravelly loam, 15 to 25 C 0.3 0.4% percent slopes Totals for Area of Interest 79.8 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Groupâ€“Snohomish County Area, Washington Arlington Temporary Storage Yard Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 4 of 4 Appendix F â€“ Operations and Maintenance Manual Stormwater Site Plan Appendix F Arlington Electrical Equipment &Pole Storage Yard July, 2016 Drip pan NOT TO SCALE Figure IV-2.2.2 Drip Pan Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. Drip pan within rails NOT TO SCALE Figure IV-2.2.3 Drip Pan Within Rails Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.4 Loading Dock with Door Skirt Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.5 Loading Dock with Overhang Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.8 Secondary Containment System Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. Lid NOT TO SCALE Figure IV-2.2.9 Locking System for Drum Lid Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.10 Covered and Bermed Containment Area Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. *Note that the secondary containment is not shown in this figure NOT TO SCALE Figure IV-2.2.11 Mounted Container - with Drip Pan Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.13 Covered Storage Area for Bulk Solids (include berm if needed) D E P A R T M E N T O F Revised December 2015 ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.14 Material Covered with Plastic Sheeting Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. TRANSMITTAL DATE: 10/3/16 TO: City of Arlington Community & Economic Development 18204 59th Avenue NE Arlington, WA 98223 FROM: Ben Davis, PE TELEPHONE NO: 425-783-8465 PROJECT: Arlington Electrical Equipment and Pole Storage Yard COPIES: file DELIVERY METHOD: REGULAR MAIL OVERNIGHT MAIL COURIER E-MAIL OTHER ITEM COPIES DATE DESCRIPTION 1 2 10/3/16 City of Arlington Comments w/responses (dated 9-14-16) 2 2 10/3/16 City of Arlington Consultant Comments w/responses (dated 9-14-16) 3 2 10/3/16 Stormwater Site Plan (Drainage Report) 4 2 10/3/16 Construction Plans (22â€x34â€) 5 2 10/3/16 Avigation Easement AS YOU REQUESTED FOR YOUR APPROVAL RETURN REQUESTED FOR YOUR INFORMATION RECORDS MANAGEMENT FOR YOUR USE FOR YOUR REVIEW COMMENTS: Initials: brd File Name: K:\Projects\Local Offices\New Local Offices\Arlington Local Office\9.0 Other Site Projects\9.6 Remote Pole Yard\Permit Documents\10-03- 16\T_10-03-16_Civl Permit Resubmittal.docx 2320 California Street Everett Washington 98201 Table of Contents 1.0 Project Overview ....................................................................................................................1 2.0 Existing Conditions Summary ...............................................................................................3 3.0 Off-Site Improvements ...........................................................................................................4 4.0 Off-site Analysis Report .........................................................................................................6 5.0 Minimum Requirements ........................................................................................................7 Governing Guidelines ...............................................................................................................9 Design Criteria ..........................................................................................................................9 6.0 Stormwater Control Plan .....................................................................................................16 Existing Site Hydrology .........................................................................................................16 Developed Site Hydrology .....................................................................................................16 Performance Standards and Goals ..........................................................................................17 7.0 Stormwater Pollution Prevention Plan (SWPPP) ..............................................................18 8.0 Special Reports and Studies .................................................................................................19 9.0 Other Permits ........................................................................................................................20 Table of Figures Figure 1 â€“ Vicinity Map .................................................................................................................2 Figure 2 â€“ Off-site Drive Aisle Aerial (2009) ...............................................................................5 Figure 3 - Flow Chart for Determining Requirements for New Development ........................8 List of Appendices Appendix A â€“ Improvement Plans Appendix B â€“ Flow Control Appendix C â€“ Runoff Treatment Appendix D â€“ Well Head Protection Zones Appendix E â€“ Soil Map Appendix F â€“ Operations and Maintenance Manual Stormwater Site Plan Page i Arlington Electrical Equipment &Pole Storage Yard July, 2016 1.0 Project Overview This Stormwater Site Plan Report provides stormwater requirements and design calculations for the proposed Snohomish County PUD No. 1 Arlington Electrical Equipment and Pole Storage Yard. The project property is located on 59th Ave NE south of the intersection with 180th Street NE, Arlington, WA 98223 within a portion of Section 22, Township 31, Range 5 East, WM. The project site is approximately 26.5 acres in area. Industrial uses border the site in all directions. 59th Ave NE borders the west side of the parcel, and railroad tracks owned by BNSF border the parcel to the east. A temporary storage yard adjacent to 59th Ave NE was constructed in 2013 creating 0.23 acres of gravel surfacing. There is no other impervious surfacing on-site. The site is predominately flat with slopes on average approximately 1-3 percent. The northeast corner of the site is approximately 10 feet higher than the western portion of the parcel. There are no known existing surface flows leaving the site. All stormwater runoff infiltrates onsite into existing outwash soils. Only a portion of the site will be developed. The 1.7 acre yard is centrally on the larger site. Access to the proposed yard will be via an access and utility easement on the AAMP (northern property owner) property. The access easement will provide a paved surface (with a minimum width of 20 feet) north to 180th Street NE and then west onto 59th Ave NE. The total disturbed area is approximately 5.0 acres. The developed storage yard is 1.7 acres in size finished with permeable gravel and asphalt. The remaining disturbed area will be used for on-site disposal of organic strippings. A water main will also be extended from the Pick and Pull site to the south connecting into the AAMP facility to the north. The proposed stormwater facilities will comply with the 2012 Department of Ecology Stormwater Management Manual for Western Washington (DOE Manual) and the City of Arlington Design and Construction Standards and Specifications. The pollution generating impervious surfaces (PGIS) will be treated by a water quality layer of material within the gravel surfacing prior to infiltrating into the existing subgrade. Refer to Section 4 of this report for additional information on the proposed drainage systems. Stormwater Site Plan Page 1 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Figure 1 â€“ Vicinity Map Project Site Stormwater Site Plan Page 2 Arlington Electrical Equipment &Pole Storage Yard July, 2016 2.0 Existing Conditions Summary The project site is approximately 26.5 acres in area. The project consists of one parcel. There is a small building, approximately 2,000 square feet centrally located on the parcel. The building, a dilapidated barn, is the only structure onsite. The rest of the parcel is vegetated predominately with grass and shrubs. There are a few trees scattered throughout the site. To the north of the site are multiple larger buildings (warehouses), and to the south of the site is a parking lot and miscellaneous buildings. The site is predominately flat with slopes on average approximately 1-3 percent. The northeast corner of the site is approximately 10 feet higher than the western portion of the parcel. There are no known existing flows leaving the site. All stormwater runoff infiltrates onsite into the existing soils. According to the Natural Resources Conservation Service (NRCS), the soils on the project site primarily consist of Lynnwood loamy sands with 0-3 % slopes with a Hydrologic Soil Group Type A. A Type A soil was used in WWHM3 for stormwater facility sizing purposes. GeoEngineers completed a geotechnical engineering report establishing a minimum of 1.2 inches/hour as the estimated long-term infiltration which was used in facility sizing. A portion of the site lies within a wellhead protection zone. A City of Arlington airport well is located approximately 2,000 feet north of the project site. The eastern half of the site which is where the proposed development is located is within the 1-year and 1-year buffer protection zones. See Appendix D for wellhead protection zone map. Stormwater Site Plan Page 3 Arlington Electrical Equipment &Pole Storage Yard July, 2016 3.0 Off-Site Improvements In order to establish paved access for emergency vehicles a 20â€™ wide drive aisle will be paved with asphalt treated base. The proposed improvements are temporary until AAMP (property owner to the north) and/or the City of Arlington construct full roadway improvements as described in â€œAgreement for Deferral of Inprovementsâ€ recording number 201112200120. The area to be paved was historically a parking lot for Bayliner employees (see Figure 2). Since the AAMP property was redeveloped (about 2011) the parking area has largely been unused. The conversion of this area to a paved surface will not impact the larger infiltration storm system that was designed to handle drainage from the gravel parking area with similar runoff characteristics. The temporary asphalt drive aisle will be replaced with construction of full roadway improvements and new stormwater facilities. Stormwater Site Plan Page 4 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Figure 2 â€“ Off-site Drive Aisle Aerial (2009) Stormwater Site Plan Page 5 Arlington Electrical Equipment &Pole Storage Yard July, 2016 4.0 Off-site Analysis Report This section evaluates the upstream and downstream drainage system. The intent of this section is to identify any existing or potential drainage impacts created or exacerbated by the proposed project and drainage facilities. Task 1: Study Area Definition The offsite analysis study area was conducted with the use of Snohomish County GIS aerial and topographic information and a topographic survey of the site. Task 2: Review of available information The following resources were utilized in preparation of this section: USGS Topographic Map Snohomish County PDS Permit, Planning and Zoning Interactive Map City of Arlington Wellhead protection Zone Map National Resources Conservation Service Web Soil Survey Task 3: Upstream & Downstream Study An upstream and downstream study was not completed because there is no upstream drainage basin and all stormwater infiltrates into the existing site soils. Stormwater Site Plan Page 6 Arlington Electrical Equipment &Pole Storage Yard July, 2016 5.0 Minimum Requirements Not all of the Minimum Requirements apply to every development or redevelopment project. The applicability varies depending on the type and size of the project. This section identifies thresholds that determine the applicability of the Minimum Requirements to different projects. The flow chart below identifies the applicable requirements. Stormwater Site Plan Page 7 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Figure 3 - Flow Chart for Determining Requirements for New Development Start Here Does the site have Yes See Redevelopment 35% or more of Minimum existing impervious Requirements and coverage? Flow Chart (Figure 2.3) No Does the project convert Â¾ acres of native vegetation to Does the project add No lawn or landscaped 5,000 square feet or areas, or convert 2.5 more of new acres of native impervious surfaces? vegetation to pasture? Yes No Yes Does the project have 2,000 square feet or All Minimum more of new, replaced, Requirements apply to or new plus replaced the new impervious impervious surfaces? surfaces and converted pervious surfaces. Yes No Minimum Does the project have Requirements #1 land-disturbing through #5 apply to activities of 7,000 the new and replaced Yes square feet or more? impervious surfaces and the land disturbed. No See Minimum Requirement #2, Construction Stormwater Pollution Prevention Stormwater Site Plan Page 8 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Governing Guidelines The project site is located within the City of Arlington. The Washington State Department of Ecology Stormwater Management Manual for Western Washington, 2012 (DOE Manual) will be used for stormwater design. The Western Washington Hydrology Model Version 2012 (WWHM), a continuous simulation model will be used to size all stormwater facilities. Design Criteria Per Figure 8 in the DOE Manual â€“ Flow chart for determining requirements for new development â€“ all minimum requirements apply to the area of the site being developed. The following section describes how each Minimum Requirement (MR) will be incorporated into the proposed project. MR #1 through #10 are addressed as follows: MR #1: Preparation of Stormwater Site Plans. This report and accompanying improvement plans constitute the Stormwater Site Plan. MR #2: Construction Stormwater Pollution Prevention (SWPPP). A SWPPP will be prepared as a separate document for use during construction. Even though the project likely does not require coverage by a Department of Ecolgoy Construction Stormwater General Permit due to on-site infiltration the District will obtain coverage in the unlikely event construction stormwater leaves the project site. The following section provides a detailed description of the BMPs to be implemented based on the 12 required elements of the SWPPP. For additional information refer to the project TESC plans and SWPPP. Element #1 â€“ 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. A large portion of the site will remain undisturbed throughout construction. Clearing limits will be delineated by silt fence and high visibility fence. The following relevant BMPs for this project include: BMP C101: Preserving Natural Vegetation BMP C233: Silt Fence BMP C103: High Visibility Plastic or Metal Fence Element #2 â€“ Establish Construction Access Stormwater Site Plan Page 9 Arlington Electrical Equipment &Pole Storage Yard July, 2016 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. The following relevant BMPs for this project include: BMP C105: Stabilized Construction Entrance BMP C107: Construction Road/Parking Area Stabilization Element #3 â€“ Control Flow Rates In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site will be controlled. The following relevant BMPs for this project include: Not applicable. It is anticipated that all construction stormwater will infiltrate into the existing subgrade. Element #4 â€“ Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before entering a receiving water body. The following relevant BMPs for this project include: BMP C220: Storm Drain Inlet Protection BMP C233: Silt Fence Element #5 â€“ 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 following relevant BMPs for this project include: BMP C120: Temporary and Permanent Seeding BMP C121: Mulching BMP C123: Plastic Covering 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. Element #6 â€“ Protect Slopes All cut and fill slopes shall be designed, constructed, and protected in a manner that minimizes erosion. The following relevant BMPs for this project include: Stormwater Site Plan Page 10 Arlington Electrical Equipment &Pole Storage Yard July, 2016 BMP C121: Mulching Element #7 â€“ Protect Permanent Drain Inlets All existing and proposed storm drain inlets and culverts made operable during construction that may receive stormwater on and downstream of the site shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. The following relevant BMPs for this project include: BMP C220: Storm Drain Inlet Protection Element #8 â€“ Stabilize Channels and Outlets There are no known channels and/or outlets on site to stabilize. Element #9 â€“ Control Pollutants All pollutants, including waste materials and demolition debris, that occur during construction 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. Vehicles, construction equipment, and/or petroleum product storage/dispensing: â€¢ 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. â€¢ Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. â€¢ Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. 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 C151). In order to prevent, reduce, or eliminate the discharge of pollutants from material delivery and storage to the stormwater system, Material Delivery and Storage Contamination (BMP C153) shall be implemented. Stormwater Site Plan Page 11 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Sanitary wastewater: Portable sanitation facilities will be firmly secured, regularly maintained, and emptied when necessary. Solid Waste: Solid waste will be stored in secure, clearly marked containers. Element #10 â€“ Control Dewatering Large scale dewatering is not anticipated during construction. A sedimentation bag with outfall into existing vegetation will be used for small volumes of localized de-watering. Element #11 â€“ 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 BMPâ€™s 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. Element #12 â€“ Manage the Project All BMPâ€™s shall be inspected and repaired in accordance with DOE permit requirements. The full project SWPPP will be kept on-site during construction. Element #13 â€“ Protect Low Impact Development BMPâ€™s The project does not have traditional low impact development BMPâ€™s. The project will utilize a custom biorention soil mix under a pervious gravel section for stormwater treatment. A geotechnical special inspection will be on-site during construction to verify the Contractor follows proper construction to no foul or over compact the pervious section material and/or subgrade. The District will also be providing periodic inspection to verify the TESC and SWPPP measures are properly installed and maintained throughout construction. MR #3: Source Control of Pollution. All known, available and reasonable Source Control BMPs shall be applied to this project. The District will promptly contain and clean up solid and liquid pollutant leaks and spills including oils and fuels. The District will periodically contract street sweeping to remove dust and debris that could contaminate stormwater and will not hose down Stormwater Site Plan Page 12 Arlington Electrical Equipment &Pole Storage Yard July, 2016 pollutants. The District will maintain the transformer storage area including periodic inspection of the oil stop valve and will repair the pavement and containment area if damaged. Any damaged and/or leaking equipment will promptly be removed from the site and repaired at the Districtâ€™s Operations Center. MR #4: Preservation of Natural Drainage Systems and Outfalls. The proposed stormwater site plan will maintain the existing outfall infiltrating into the existing subgrade. MR #5: On-Site Stormwater Management. The DOE Manual requires the use of on-site Stormwater Management BMPs to infiltrate, disperse, and retain stormwater runoff on-site to the maximum extent feasible without causing flooding or erosion impacts. Existing onsite soils and the proposed stormwater facility design allows for 100% infiltration of all proposed impervious and pervious surfaces from 50% of the 2 year peak flow up to the full 50 year peak flow as modeled by WWHM2012. MR #6: Runoff Treatment. The developed portion of the site will be used for industrial uses which requires enhanced water quality treatment per the DOE Manual. Treatment of stormwater runoff will be provided by a custom bioretention soil mix within the pervious (or gravel) areas. The custom bioretention soil mix complies with the Volume V, page 7-17 of the DOE Manual. A custom soil mix will be used due to a couple factors. The existing topsoil does have a cation exchange rate greater than five, however the depth of the topsoil is less than 18 inches which is insufficient for water quality treatment. The site will also be developed in the winter months which is not ideal for mixing and reuse of existing on-site materials. The paved access drives will be designed to sheet flow drainage into the pervious gravel sections for treatment prior to infiltration. The gravel areas have been designed to treat the tributary pavement areas. In order to allow for treatment within the 18â€ water quality section without backwatering during large storm events a 4â€ layer of rock was also incorporated into the gravel section to allow for ponding at the subgrade interface prior to infiltrating into the subgrade. The site design also incorporates a paved and curbed area for transformer storage. The transformers stored on-site are filled with a non-conductive mineral oil. Mineral oil transfer and/or filling will not occur on-site so the spill potential on-site is limited, however vandalism has resulted in oil spills of stored and/or operational transformer in the past. To reduce the risk of contaminating soil as a result of an accidental spill an oil stop valve and curbed area have been included in the site development plans. During Stormwater Site Plan Page 13 Arlington Electrical Equipment &Pole Storage Yard July, 2016 normal operations the transformer pavement area will drain onto the gravel section via a storm drain outlet and will be treated by the water quality section within the gravel section. The stormwater quality treatment design is discussed in more detail in Appendix C of this report. MR #7: Flow Control. All stormwater generated on the project site from the proposed impervious and pervious surfaces from 50% of the 2 year peak flow up to the full 50 year peak flow as modeled by WWHM2012 will infiltrate into the subgrade mimicking existing conditions. The long term infiltration rate of the subgrade soils has been established by grain size analysis conducted by GeoEngineers (see Geotechnical report dated May 4, 2016). GeoEngineers took several samples of the subgrade material at different locations and depths on the 26.5 acre site. The site soils are consistent briefly described as sand with a higher percentage of silt at lower depths. The proposed gravel section will require stripping a minimum of 2.5â€™ from the existing site for construction of the proposed section. The low long-term infiltration rate calculated by GeoEngineers is 1.2 inches/hour at 3 feet below existing grade. The high long-term infiltration rate calculated by GeoEngineers is 7.7 inches/hour at 6 feet below existing grade. For design of the infiltration facilities a conservative rate of 1.2 inches per hour was used to verify 100% infiltration and that ponding of water at the subgrade line did not backwater into the treatment section. The DOE Manual in Volume III, page 3-85 states that the base of all infiltration basins or trenches shall be greater or equal to 5 feet above the seasonal high water mark. This can be reduced to 3 feet with a groundwater mounding analysis. A Hydrogeologic Assessment was completed to support the site development and address this design constraint as well as discuss the sole source aquifer and it relates to the proposed site development in more detail. Two data loggers were installed and measured seasonal groundwater elevations during the rainy season for several years. In general terms the groundwater elevation from existing subgrade deepens from the south property line to the north. The maximum recorded groundwater elevation below existing grade near the middle of the site is approximately 7 feet. The maximum recorded groundwater elevation below existing grade near the south end of the site is approximately 4 feet. The proposed development borders the north property line and the bottom of the proposed facilities 2.5 feet below existing grade. Assuming the seasonal groundwater level deepens to the north the designed facilities have the required separation. This is consistent with visual observations of two stormwater ponds on the AAMP property which border the development to the north. See separate Hydrogeologic Assessment completed by GeoEngineers dated April 26, 2016 for additional information. Stormwater Site Plan Page 14 Arlington Electrical Equipment &Pole Storage Yard July, 2016 The imported materials that will be placed on the prepared subgrade in the gravel areas have a low percentage of fines and will not restrict infiltration of stormwater into the subgrade. The subgrade is the confining layer of material and the infiltration rate through this material was used in design. The stormwater infiltration design is discussed in more detail in Appendix B of this report. MR #8: Wetlands Protection There are no wetlands or wetland buffers impacting the site. MR #9: Basin/Watershed Planning. A portion of the site lies within a wellhead protection zone. A City of Arlington airport well is located approximately 2,000 feet north of the project site. The proposed gravel section with an 18 inch water quality section will provide adequate treatment of stormwater prior to infiltration reducing potential impacts to the water source. See Appendix D for wellhead protection zone map. MR #10: Operation and Maintenance. An Operation and Maintenance Manual is included in Appendix F of this report. Stormwater Site Plan Page 15 Arlington Electrical Equipment &Pole Storage Yard July, 2016 6.0 Stormwater Control Plan The following section details the selection of stormwater control BMPs and facilities that will serve the proposed project in its developed condition. The selection of stormwater control and BMP facilities follows the 2012 DOE Manual. Existing Site Hydrology The project site is 26.5-acres in area with an old dilapidated barn in the center of the property. Vegetation of the site consists of recently mowed grasses, scotch broom, blackberry and a few large deciduous and conifer trees. The site is predominately flat with slopes of approximately 2 percent. The north east corner of the site is the high side, and gently slopes to the west. The west side of the site at NE 59th Street is the low side of the site. Off-site flows are limited. Properties to the north and south are developed with existing site drainage systems. There is no observed runoff coming from the project site. Based on site observation and the geotechnical report, the majority of all stormwater runoff infiltrates into the existing soils. Refer to the Geotechnical Report prepared for this project for additional soils information. Developed Site Hydrology Developed site conditions will mimic existing site drainage conditions by infiltrating stormwater runoff into the existing subgrade. Only a portion of the 26.5 acre site will be developed for creation of the proposed Arlington Electrical Equipment and Pole Storage Yard. The developed yard is approximately 1.7 acres. During development an additional 1.5 acres will be disturbed for on-site disposal of organic strippings. The paved access drives sheet flow drainage into the pervious gravel sections for treatment prior to infiltration. The gravel areas have been designed to treat tributary pavement areas with an 18â€ water quality section. The site design also incorporates a paved, curbed area with an oil stop valve for transformer storage to reduce the risk of contaminating soil as a result of an accidental spill. During normal operations the transformer pavement area will drain onto the gravel section via a storm drain outlet and will be treated by the water quality section within the gravel section. Stormwater Site Plan Page 16 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Performance Standards and Goals The stormwater facilities have been designed using the Western Washington Hydrology Model Version 2012. The stormwater discharges match developed discharge durations to pre-developed durations for the range of pre-developed discharge rates from 50% of the 2-year peak flow up to the full 50-year peak flow. WWHM2012 is based on continuous simulation hydrology and according to the 2012 SMMWW is acceptable for sizing infiltration and water quality facilities in Western Washington. The pre-developed condition is assumed to be forested with Type A/B soils. For further detailed information concerning the design of the stormwater facilities reference Appendices B & C. Stormwater Site Plan Page 17 Arlington Electrical Equipment &Pole Storage Yard July, 2016 7.0 Stormwater Pollution Prevention Plan (SWPPP) A site specific SWPPP will be provided prior to construction. Stormwater Site Plan Page 18 Arlington Electrical Equipment &Pole Storage Yard July, 2016 8.0 Special Reports and Studies â€¢ Critical Area Reconnaissance - GeoEngineers, Inc., June 28, 2016. â€¢ Geotechnical Engineering Report - GeoEngineers, Inc., May 4, 2016 â€¢ Hydrogeologic Assessment - GeoEngineers, Inc., April 26, 2016 â€¢ Traffic Analysis â€“ Gibson Traffic Consultants, Inc., April 21, 2016 â€¢ AHERA Inspection Report â€“ Snohomish County PUD No. 1, July 14, 2014 â€¢ Cultural Resources Assessment - Cultural Resources Consultants, July 8, 2016 Stormwater Site Plan Page 19 Arlington Electrical Equipment &Pole Storage Yard July, 2016 9.0 Other Permits â€¢ City of Arlington Grading Permit â€¢ City of Arlington Zoning Permit â€¢ City of Arlington Civil Permit â€¢ Washington State Department of Ecology Construction Stormwater General Permit â€¢ SEPA Threshold Determination (Snohomish County PUD No. 1 Lead Agency) â€¢ City of Arlington Avigation Easement Stormwater Site Plan Page 20 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Appendix A â€“ Improvement Plans Stormwater Site Plan Appendix A Arlington Electrical Equipment &Pole Storage Yard July, 2016 Lockey TE hydraulic closer sized to accommodate door. 09/22/2016 Appendix B â€“ Flow Control Stormwater Site Plan Appendix B Arlington Electrical Equipment &Pole Storage Yard July, 2016 Sedimentation and Erosion Control In our opinion, the erosion potential of the on-site soils is low to moderate. Construction activities, including stripping and grading, will expose soils to the erosion effects of wind and water. The amount and potential impacts of erosion are partly related to the time of year that construction actually occurs. Wet weather construction will increase the amount and extent of erosion and potential sedimentation. Erosion and sedimentation control measures may be implemented by using a combination of interceptor swales, straw bale barriers, silt fences and straw mulch for temporary erosion protection of exposed soils. All disturbed areas should be finish graded and seeded as soon as practicable to reduce the risk of erosion. Erosion and sedimentation control measures should be installed and maintained in accordance with the requirements of the City of Arlington. Infiltration Facilities We understand that the District is planning to design the unpaved gravel areas for stormwater infiltration at the site. We understand that the pole storage yard gravel surfacing section will be underlain by a bioretention soil mix layer for stormwater treatment. We also understand that infiltration requirements will be designed in accordance with the Washington State Department of Ecologyâ€™s 2012 SWMMWW. Since the soils have not been glacially consolidated, a pilot infiltration test (PIT) is not required in order to estimate an initial saturated hydraulic conductivity (Ksat) per Section 3.3.4 of the SWMMWW. The initial saturated hydraulic conductivity values were estimated using the grain size analysis method per Section 3.3.6 of the SWMMWW. We completed eight grain size analyses on selected samples from our explorations. The estimated long-term (factored) saturated hydraulic conductivity values for each sample is summarized in Table 5. TABLE 5. ESTIMATED LONG-TERM SATURATED HYDRAULIC CONDUCTIVITY Long-Term Rate (factored) Ksat USCS Depth D10 D60 D90 ffines Exploration Symbol (feet) (mm) (mm) (mm) (%) (cm/s) (in/hr) B-2 SP-SM 5 0.170 5.37 16.2 5.8 3.81 x 10-3 5.4 B-3 SM 2Â½ 0.040 0.61 8.6 13.2 1.62 x 10-3 2.3 B-5 SP-SM 5 0.100 3.07 25.5 8.1 1.76 x 10-3 2.5 TP-1 SP 6 0.120 0.31 0.7 3.7 4.52 x 10-3 6.4 TP-3 SP 6 0.230 1.22 13.3 2.6 5.43 x 10-3 7.7 TP-7 SP-SM 3 0.070 0.51 3.8 11.2 2.33 x 10-3 3.3 TP-8 SM 3 0.001 0.23 0.7 27.1 8.47 x 10-4 1.2 TP-8 SP 6 0.200 0.85 8.6 2.8 5.36 x 10-3 7.6 Notes: mm = millimeter; cm/s = centimeters per second; in/hr = inchers per hour Conservative Rate used for design May 4, 2016 | Page 12 File No. 0482-051-03 NORTH CENTER INFILTRATION AREA NORTH CENTER TRIBUTARY INFILTRATION AREA PAVEMENT AREA 5,746SF = 75.8^2SF 7,489 SF = 0.17AC WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Arlington (North Center) Site Name: PUD Pole Yard Site Address: 59th Ave NE City : Arlington Report Date: 10/3/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.20 Version Date: 2016/02/25 Version : 4.2.12 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : PreDev North Center Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .3 Pervious Total 0.3 Impervious Land Use acre Impervious Total 0 Basin Total 0.3 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : North Center Pervious Bottom Length: 75.80 ft. Bottom Width: 75.80 ft. Trench bottom slope 1: 0 To 1 Total gravel area is Trench Left side slope 0: 0 To 1 5,746 square feet Trench right side slope 2: 0 To 1 Material thickness of first layer: 0.6666666 Pour Space of material for first layer: 0.4 Material thickness of second layer: 1.5 Pour Space of material for second layer: 0.4 Material thickness of third layer: 0.333333 Pour Space of material for third layer: 0.4 Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 57.77 Total Volume Through Riser (ac-ft.): 0 No backwater into treatment layer Total Volume Through Facility (ac-ft.): 57.77 above 4 inches of rock at base of facility Percent Infiltrated: 100 Total Precip Applied to Facility: 26.715 Total Evap From Facility: 1.834 Discharge Structure Riser Height: 0.333333333 ft. Riser Diameter: 24 in. Precipitation applied to facility 5,746 sf 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 0.131 0.000 0.000 0.000 0.0148 0.131 0.000 0.000 0.159 0.0296 0.131 0.001 0.000 0.159 0.0444 0.131 0.002 0.000 0.159 0.0593 0.131 0.003 0.000 0.159 0.0741 0.131 0.003 0.000 0.159 0.0889 0.131 0.004 0.000 0.159 0.1037 0.131 0.005 0.000 0.159 0.1185 0.131 0.006 0.000 0.159 0.1333 0.131 0.007 0.000 0.159 0.1481 0.131 0.007 0.000 0.159 0.1630 0.131 0.008 0.000 0.159 0.1778 0.131 0.009 0.000 0.159 0.1926 0.131 0.010 0.000 0.159 0.2074 0.131 0.010 0.000 0.159 0.2222 0.131 0.011 0.000 0.159 0.2370 0.131 0.012 0.000 0.159 0.2519 0.131 0.013 0.000 0.159 0.2667 0.131 0.014 0.000 0.159 0.2815 0.131 0.014 0.000 0.159 0.2963 0.131 0.015 0.000 0.159 0.3111 0.131 0.016 0.000 0.159 0.3259 0.131 0.017 0.000 0.159 0.3407 0.131 0.018 0.013 0.159 0.3556 0.131 0.018 0.070 0.159 0.3704 0.131 0.019 0.151 0.159 0.3852 0.131 0.020 0.250 0.159 0.4000 0.131 0.021 0.365 0.159 0.4148 0.131 0.021 0.493 0.159 0.4296 0.131 0.022 0.633 0.159 0.4444 0.131 0.023 0.784 0.159 0.4593 0.131 0.024 0.946 0.159 0.4741 0.131 0.025 1.117 0.159 0.4889 0.131 0.025 1.297 0.159 0.5037 0.131 0.026 1.486 0.159 0.5185 0.131 0.027 1.682 0.159 0.5333 0.131 0.028 1.886 0.159 0.5481 0.131 0.028 2.097 0.159 0.5630 0.131 0.029 2.314 0.159 0.5778 0.131 0.030 2.537 0.159 0.5926 0.131 0.031 2.766 0.159 0.6074 0.131 0.032 3.000 0.159 0.6222 0.131 0.032 3.239 0.159 0.6370 0.131 0.033 3.482 0.159 0.6519 0.131 0.034 3.729 0.159 0.6667 0.131 0.035 3.979 0.159 0.6815 0.131 0.036 4.232 0.159 0.6963 0.131 0.036 4.487 0.159 0.7111 0.131 0.037 4.745 0.159 0.7259 0.131 0.038 5.004 0.159 0.7407 0.131 0.039 5.264 0.159 0.7556 0.131 0.039 5.525 0.159 0.7704 0.131 0.040 5.786 0.159 0.7852 0.131 0.041 6.047 0.159 0.8000 0.131 0.042 6.307 0.159 0.8148 0.131 0.043 6.566 0.159 0.8296 0.131 0.043 6.823 0.159 0.8444 0.131 0.044 7.078 0.159 0.8593 0.131 0.045 7.331 0.159 0.8741 0.131 0.046 7.580 0.159 0.8889 0.131 0.046 7.826 0.159 0.9037 0.131 0.047 8.068 0.159 0.9185 0.131 0.048 8.306 0.159 0.9333 0.131 0.049 8.540 0.159 0.9481 0.131 0.050 8.768 0.159 0.9630 0.131 0.050 8.991 0.159 0.9778 0.131 0.051 9.208 0.159 0.9926 0.131 0.052 9.419 0.159 1.0074 0.131 0.053 9.624 0.159 1.0222 0.131 0.053 9.823 0.159 1.0370 0.131 0.054 10.01 0.159 1.0518 0.131 0.055 10.20 0.159 1.0667 0.131 0.056 10.37 0.159 1.0815 0.131 0.057 10.54 0.159 1.0963 0.131 0.057 10.71 0.159 1.1111 0.131 0.058 10.86 0.159 1.1259 0.131 0.059 11.01 0.159 1.1407 0.131 0.060 11.15 0.159 1.1556 0.131 0.061 11.29 0.159 1.1704 0.131 0.061 11.41 0.159 1.1852 0.131 0.062 11.53 0.159 1.2000 0.131 0.063 11.65 0.159 1.2148 0.131 0.064 11.76 0.159 1.2296 0.131 0.064 11.86 0.159 1.2444 0.131 0.065 11.96 0.159 1.2593 0.131 0.066 12.05 0.159 1.2741 0.131 0.067 12.14 0.159 1.2889 0.131 0.068 12.22 0.159 1.3037 0.131 0.068 12.30 0.159 1.3185 0.131 0.069 12.38 0.159 ___________________________________________________________________ Name : Lateral I Basin 1 Bypass: No pavement tributuary to Impervious Land Use acre gravel area ROADS FLAT LAT 0.17 ___________________________________________________________________ Element Flows To: Outlet 1 Outlet 2 North Center Pervious ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.3 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.17 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000344 5 year 0.000747 10 year 0.001198 25 year 0.002092 50 year 0.003092 100 year 0.004485 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.000 1950 0.001 0.000 1951 0.000 0.000 1952 0.000 0.000 1953 0.000 0.000 1954 0.002 0.000 1955 0.001 0.000 1956 0.000 0.000 1957 0.000 0.000 1958 0.000 0.000 1959 0.001 0.000 1960 0.000 0.000 1961 0.001 0.000 1962 0.000 0.000 1963 0.000 0.000 1964 0.001 0.000 1965 0.000 0.000 1966 0.000 0.000 1967 0.000 0.000 1968 0.000 0.000 1969 0.000 0.000 1970 0.000 0.000 1971 0.001 0.000 1972 0.000 0.000 1973 0.000 0.000 1974 0.001 0.000 1975 0.000 0.000 1976 0.001 0.000 1977 0.000 0.000 1978 0.000 0.000 1979 0.000 0.000 1980 0.000 0.000 1981 0.000 0.000 1982 0.000 0.000 1983 0.000 0.000 1984 0.000 0.000 1985 0.000 0.000 1986 0.002 0.000 1987 0.001 0.000 1988 0.000 0.000 1989 0.000 0.000 1990 0.000 0.000 1991 0.000 0.000 1992 0.000 0.000 1993 0.000 0.000 1994 0.000 0.000 1995 0.000 0.000 1996 0.003 0.000 1997 0.007 0.000 1998 0.000 0.000 1999 0.000 0.000 2000 0.000 0.000 2001 0.000 0.000 2002 0.000 0.000 2003 0.000 0.000 2004 0.000 0.000 2005 0.000 0.000 2006 0.008 0.000 2007 0.000 0.000 2008 0.000 0.000 2009 0.000 0.000 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0080 0.0000 2 0.0074 0.0000 3 0.0027 0.0000 4 0.0021 0.0000 5 0.0017 0.0000 6 0.0014 0.0000 7 0.0013 0.0000 8 0.0012 0.0000 9 0.0011 0.0000 10 0.0008 0.0000 11 0.0007 0.0000 12 0.0006 0.0000 13 0.0005 0.0000 14 0.0005 0.0000 15 0.0005 0.0000 16 0.0005 0.0000 17 0.0005 0.0000 18 0.0004 0.0000 19 0.0004 0.0000 20 0.0004 0.0000 21 0.0004 0.0000 22 0.0004 0.0000 23 0.0003 0.0000 24 0.0002 0.0000 25 0.0002 0.0000 26 0.0002 0.0000 27 0.0002 0.0000 28 0.0002 0.0000 29 0.0002 0.0000 30 0.0002 0.0000 31 0.0002 0.0000 32 0.0002 0.0000 33 0.0002 0.0000 34 0.0002 0.0000 35 0.0002 0.0000 36 0.0002 0.0000 37 0.0002 0.0000 38 0.0002 0.0000 39 0.0002 0.0000 40 0.0002 0.0000 41 0.0002 0.0000 42 0.0002 0.0000 43 0.0002 0.0000 44 0.0002 0.0000 45 0.0002 0.0000 46 0.0002 0.0000 47 0.0002 0.0000 48 0.0002 0.0000 49 0.0002 0.0000 50 0.0002 0.0000 51 0.0002 0.0000 52 0.0002 0.0000 53 0.0002 0.0000 54 0.0002 0.0000 55 0.0002 0.0000 56 0.0002 0.0000 57 0.0002 0.0000 58 0.0002 0.0000 59 0.0002 0.0000 60 0.0002 0.0000 61 0.0002 0.0000 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0002 2363 0 0 Pass 0.0002 1352 0 0 Pass 0.0002 470 0 0 Pass 0.0003 112 0 0 Pass 0.0003 103 0 0 Pass 0.0003 89 0 0 Pass 0.0003 77 0 0 Pass 0.0004 66 0 0 Pass 0.0004 62 0 0 Pass 0.0004 58 0 0 Pass 0.0005 54 0 0 Pass 0.0005 50 0 0 Pass 0.0005 49 0 0 Pass 0.0006 47 0 0 Pass 0.0006 43 0 0 Pass 0.0006 40 0 0 Pass 0.0006 36 0 0 Pass 0.0007 36 0 0 Pass 0.0007 32 0 0 Pass 0.0007 31 0 0 Pass 0.0008 31 0 0 Pass 0.0008 29 0 0 Pass 0.0008 29 0 0 Pass 0.0009 27 0 0 Pass 0.0009 26 0 0 Pass 0.0009 26 0 0 Pass 0.0009 26 0 0 Pass 0.0010 25 0 0 Pass 0.0010 23 0 0 Pass 0.0010 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 21 0 0 Pass 0.0012 19 0 0 Pass 0.0012 18 0 0 Pass 0.0012 17 0 0 Pass 0.0013 16 0 0 Pass 0.0013 16 0 0 Pass 0.0013 15 0 0 Pass 0.0014 15 0 0 Pass 0.0014 14 0 0 Pass 0.0014 13 0 0 Pass 0.0014 13 0 0 Pass 0.0015 13 0 0 Pass 0.0015 13 0 0 Pass 0.0015 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0017 11 0 0 Pass 0.0017 11 0 0 Pass 0.0017 11 0 0 Pass 0.0018 11 0 0 Pass 0.0018 11 0 0 Pass 0.0018 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0021 10 0 0 Pass 0.0021 10 0 0 Pass 0.0021 9 0 0 Pass 0.0021 9 0 0 Pass 0.0022 8 0 0 Pass 0.0022 8 0 0 Pass 0.0022 8 0 0 Pass 0.0023 8 0 0 Pass 0.0023 8 0 0 Pass 0.0023 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 7 0 0 Pass 0.0026 7 0 0 Pass 0.0027 7 0 0 Pass 0.0027 7 0 0 Pass 0.0027 6 0 0 Pass 0.0028 6 0 0 Pass 0.0028 6 0 0 Pass 0.0028 6 0 0 Pass 0.0029 6 0 0 Pass 0.0029 6 0 0 Pass 0.0029 6 0 0 Pass 0.0029 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0031 5 0 0 Pass 0.0031 5 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 North Center Pervious POC N 52.61 N 99.92 Total Volume Infiltrated 52.61 0.00 0.00 99.92 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd 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 Â© by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. less than 4 inches SOUTH CENTER INFILTRATION AREA TRIBUTARY PAVEMENT AREA 6,181 SF = 0.14AC SOUTH CENTER INFILTRATION AREA 7,868SF = 88.7^2SF WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Arlington (South Center) Site Name: PUD Pole Yard Site Address: 59th Ave NE City : Arlington Report Date: 10/3/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.20 Version Date: 2016/02/25 Version : 4.2.12 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : PreDev South Center Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .32 Pervious Total 0.32 Impervious Land Use acre Impervious Total 0 Basin Total 0.32 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : South Center Pervious Bottom Length: 88.70 ft. Bottom Width: 88.70 ft. Trench bottom slope 1: 0 To 1 Total gravel area is Trench Left side slope 0: 0 To 1 7,868 square feet Trench right side slope 2: 0 To 1 Material thickness of first layer: 0.6666 Pour Space of material for first layer: 0.4 Material thickness of second layer: 1.5 Pour Space of material for second layer: 0.4 Material thickness of third layer: 0.3333 No backwater into treatment layer Pour Space of material for third layer: 0.4 above 4 inches of rock at base of facility Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 62.013 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 62.013 Percent Infiltrated: 100 Total Precip Applied to Facility: 37.219 Total Evap From Facility: 2.314 Discharge Structure Riser Height: 0.3333 ft. Precipitation applied to Riser Diameter: 24 in. facility 7,868 sf 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 0.180 0.000 0.000 0.000 0.0278 0.180 0.002 0.000 0.218 0.0556 0.180 0.004 0.000 0.218 0.0833 0.180 0.006 0.000 0.218 0.1111 0.180 0.008 0.000 0.218 0.1389 0.180 0.010 0.000 0.218 0.1667 0.180 0.012 0.000 0.218 0.1944 0.180 0.014 0.000 0.218 0.2222 0.180 0.016 0.000 0.218 0.2500 0.180 0.018 0.000 0.218 0.2778 0.180 0.020 0.000 0.218 0.3056 0.180 0.022 0.000 0.218 0.3333 0.180 0.024 0.000 0.218 0.3611 0.180 0.026 0.098 0.218 0.3889 0.180 0.028 0.278 0.218 0.4167 0.180 0.030 0.510 0.218 0.4444 0.180 0.032 0.785 0.218 0.4722 0.180 0.034 1.096 0.218 0.5000 0.180 0.036 1.438 0.218 0.5278 0.180 0.038 1.809 0.218 0.5556 0.180 0.040 2.205 0.218 0.5833 0.180 0.042 2.623 0.218 0.6111 0.180 0.044 3.060 0.218 0.6389 0.180 0.046 3.513 0.218 0.6667 0.180 0.048 3.979 0.218 0.6944 0.180 0.050 4.456 0.218 0.7222 0.180 0.052 4.940 0.218 0.7500 0.180 0.054 5.428 0.218 0.7778 0.180 0.056 5.917 0.218 0.8056 0.180 0.058 6.405 0.218 0.8333 0.180 0.060 6.888 0.218 0.8611 0.180 0.062 7.363 0.218 0.8889 0.180 0.064 7.827 0.218 0.9167 0.180 0.066 8.277 0.218 0.9444 0.180 0.068 8.712 0.218 0.9722 0.180 0.070 9.128 0.218 1.0000 0.180 0.072 9.523 0.218 1.0278 0.180 0.074 9.896 0.218 1.0556 0.180 0.076 10.24 0.218 1.0833 0.180 0.078 10.56 0.218 1.1111 0.180 0.080 10.86 0.218 1.1389 0.180 0.082 11.14 0.218 1.1667 0.180 0.084 11.38 0.218 1.1944 0.180 0.086 11.61 0.218 1.2222 0.180 0.088 11.81 0.218 1.2500 0.180 0.090 11.99 0.218 1.2778 0.180 0.092 12.16 0.218 1.3056 0.180 0.094 12.31 0.218 1.3333 0.180 0.096 12.59 0.218 1.3611 0.180 0.098 12.77 0.218 1.3889 0.180 0.100 12.94 0.218 1.4167 0.180 0.102 13.11 0.218 1.4444 0.180 0.104 13.28 0.218 1.4722 0.180 0.106 13.44 0.218 1.5000 0.180 0.108 13.60 0.218 1.5278 0.180 0.110 13.76 0.218 1.5556 0.180 0.112 13.92 0.218 1.5833 0.180 0.114 14.08 0.218 1.6111 0.180 0.116 14.24 0.218 1.6389 0.180 0.118 14.39 0.218 1.6667 0.180 0.120 14.54 0.218 1.6944 0.180 0.122 14.69 0.218 1.7222 0.180 0.124 14.84 0.218 1.7500 0.180 0.126 14.99 0.218 1.7778 0.180 0.128 15.14 0.218 1.8056 0.180 0.130 15.28 0.218 1.8333 0.180 0.132 15.43 0.218 1.8611 0.180 0.134 15.57 0.218 1.8889 0.180 0.136 15.71 0.218 1.9167 0.180 0.138 15.85 0.218 1.9444 0.180 0.140 15.99 0.218 1.9722 0.180 0.142 16.12 0.218 2.0000 0.180 0.144 16.26 0.218 2.0278 0.180 0.146 16.40 0.218 2.0556 0.180 0.148 16.53 0.218 2.0833 0.180 0.150 16.66 0.218 2.1111 0.180 0.152 16.79 0.218 2.1389 0.180 0.154 16.92 0.218 2.1667 0.180 0.156 17.05 0.218 2.1944 0.180 0.158 17.18 0.218 2.2222 0.180 0.160 17.31 0.218 2.2500 0.180 0.162 17.44 0.218 2.2778 0.180 0.164 17.56 0.218 2.3056 0.180 0.166 17.69 0.218 2.3333 0.180 0.168 17.81 0.218 2.3611 0.180 0.170 17.94 0.218 2.3889 0.180 0.172 18.06 0.218 2.4167 0.180 0.174 18.18 0.218 2.4444 0.180 0.176 18.30 0.218 2.4722 0.180 0.178 18.42 0.218 2.5000 0.180 0.183 18.54 0.218 ___________________________________________________________________ Name : Impervious Bypass: No pavement tributuary to Impervious Land Use acre gravel area ROADS FLAT LAT 0.14 ___________________________________________________________________ Element Flows To: Outlet 1 Outlet 2 South Center Pervious ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.32 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.14 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000367 5 year 0.000797 10 year 0.001278 25 year 0.002232 50 year 0.003298 100 year 0.004784 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.000 1950 0.001 0.000 1951 0.001 0.000 1952 0.000 0.000 1953 0.000 0.000 1954 0.002 0.000 1955 0.001 0.000 1956 0.000 0.000 1957 0.000 0.000 1958 0.000 0.000 1959 0.001 0.000 1960 0.000 0.000 1961 0.001 0.000 1962 0.000 0.000 1963 0.000 0.000 1964 0.001 0.000 1965 0.000 0.000 1966 0.000 0.000 1967 0.000 0.000 1968 0.000 0.000 1969 0.000 0.000 1970 0.000 0.000 1971 0.001 0.000 1972 0.000 0.000 1973 0.000 0.000 1974 0.001 0.000 1975 0.000 0.000 1976 0.001 0.000 1977 0.000 0.000 1978 0.000 0.000 1979 0.001 0.000 1980 0.000 0.000 1981 0.000 0.000 1982 0.000 0.000 1983 0.000 0.000 1984 0.000 0.000 1985 0.000 0.000 1986 0.002 0.000 1987 0.001 0.000 1988 0.000 0.000 1989 0.000 0.000 1990 0.000 0.000 1991 0.000 0.000 1992 0.000 0.000 1993 0.000 0.000 1994 0.000 0.000 1995 0.000 0.000 1996 0.003 0.000 1997 0.008 0.000 1998 0.000 0.000 1999 0.000 0.000 2000 0.000 0.000 2001 0.000 0.000 2002 0.000 0.000 2003 0.000 0.000 2004 0.000 0.000 2005 0.000 0.000 2006 0.009 0.000 2007 0.000 0.000 2008 0.000 0.000 2009 0.000 0.000 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0085 0.0000 2 0.0079 0.0000 3 0.0029 0.0000 4 0.0023 0.0000 5 0.0018 0.0000 6 0.0015 0.0000 7 0.0013 0.0000 8 0.0012 0.0000 9 0.0012 0.0000 10 0.0008 0.0000 11 0.0007 0.0000 12 0.0007 0.0000 13 0.0006 0.0000 14 0.0006 0.0000 15 0.0005 0.0000 16 0.0005 0.0000 17 0.0005 0.0000 18 0.0005 0.0000 19 0.0005 0.0000 20 0.0004 0.0000 21 0.0004 0.0000 22 0.0004 0.0000 23 0.0003 0.0000 24 0.0003 0.0000 25 0.0003 0.0000 26 0.0003 0.0000 27 0.0003 0.0000 28 0.0003 0.0000 29 0.0003 0.0000 30 0.0003 0.0000 31 0.0003 0.0000 32 0.0003 0.0000 33 0.0003 0.0000 34 0.0003 0.0000 35 0.0003 0.0000 36 0.0003 0.0000 37 0.0003 0.0000 38 0.0003 0.0000 39 0.0003 0.0000 40 0.0003 0.0000 41 0.0003 0.0000 42 0.0003 0.0000 43 0.0003 0.0000 44 0.0003 0.0000 45 0.0003 0.0000 46 0.0003 0.0000 47 0.0003 0.0000 48 0.0003 0.0000 49 0.0003 0.0000 50 0.0003 0.0000 51 0.0003 0.0000 52 0.0003 0.0000 53 0.0003 0.0000 54 0.0003 0.0000 55 0.0002 0.0000 56 0.0002 0.0000 57 0.0002 0.0000 58 0.0002 0.0000 59 0.0002 0.0000 60 0.0002 0.0000 61 0.0002 0.0000 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0002 2391 0 0 Pass 0.0002 1364 0 0 Pass 0.0002 450 0 0 Pass 0.0003 112 0 0 Pass 0.0003 103 0 0 Pass 0.0003 89 0 0 Pass 0.0004 77 0 0 Pass 0.0004 66 0 0 Pass 0.0004 61 0 0 Pass 0.0005 58 0 0 Pass 0.0005 54 0 0 Pass 0.0005 50 0 0 Pass 0.0006 49 0 0 Pass 0.0006 47 0 0 Pass 0.0006 43 0 0 Pass 0.0007 40 0 0 Pass 0.0007 36 0 0 Pass 0.0007 36 0 0 Pass 0.0007 32 0 0 Pass 0.0008 31 0 0 Pass 0.0008 31 0 0 Pass 0.0008 29 0 0 Pass 0.0009 29 0 0 Pass 0.0009 27 0 0 Pass 0.0009 26 0 0 Pass 0.0010 26 0 0 Pass 0.0010 26 0 0 Pass 0.0010 25 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0012 23 0 0 Pass 0.0012 23 0 0 Pass 0.0012 21 0 0 Pass 0.0013 19 0 0 Pass 0.0013 18 0 0 Pass 0.0013 17 0 0 Pass 0.0013 16 0 0 Pass 0.0014 16 0 0 Pass 0.0014 15 0 0 Pass 0.0014 15 0 0 Pass 0.0015 14 0 0 Pass 0.0015 13 0 0 Pass 0.0015 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0017 13 0 0 Pass 0.0017 13 0 0 Pass 0.0017 13 0 0 Pass 0.0018 13 0 0 Pass 0.0018 11 0 0 Pass 0.0018 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0021 11 0 0 Pass 0.0021 11 0 0 Pass 0.0021 11 0 0 Pass 0.0022 11 0 0 Pass 0.0022 11 0 0 Pass 0.0022 10 0 0 Pass 0.0023 9 0 0 Pass 0.0023 9 0 0 Pass 0.0023 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 8 0 0 Pass 0.0027 8 0 0 Pass 0.0027 8 0 0 Pass 0.0027 8 0 0 Pass 0.0028 8 0 0 Pass 0.0028 7 0 0 Pass 0.0028 7 0 0 Pass 0.0029 7 0 0 Pass 0.0029 7 0 0 Pass 0.0029 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0031 6 0 0 Pass 0.0031 6 0 0 Pass 0.0031 6 0 0 Pass 0.0032 6 0 0 Pass 0.0032 6 0 0 Pass 0.0032 6 0 0 Pass 0.0033 5 0 0 Pass 0.0033 5 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 South Center Pervious POC N 56.46 N 99.96 Total Volume Infiltrated 56.46 0.00 0.00 99.96 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd 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 Â© by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. less than 4 inches PERIMETER INFILTRATION AREA TRIBUTARY PAVEMENT AREA 11,063 SF = 0.25AC PERIMETER INFILTRATION AREA 31,223SF = 176.70^2SF WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Arlington (Perimeter) Site Name: PUD Pole Yard Site Address: 59th Ave NE City : Arlington Report Date: 10/3/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.20 Version Date: 2016/02/25 Version : 4.2.12 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : PreDev Perimeter Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .96 Pervious Total 0.96 Impervious Land Use acre Impervious Total 0 Basin Total 0.96 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : North Center Pervious Bottom Length: 176.70 ft. Bottom Width: 176.70 ft. Trench bottom slope 1: 0 To 1 Total gravel area is Trench Left side slope 0: 0 To 1 31,223 square feet Trench right side slope 2: 0 To 1 Material thickness of first layer: 0.66666 Pour Space of material for first layer: 0.4 Material thickness of second layer: 1.5 Pour Space of material for second layer: 0.4 No backwater into treatment layer Material thickness of third layer: 0.333 above 4 inches of rock at base of facility Pour Space of material for third layer: 0.4 Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 186.463 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 186.463 Percent Infiltrated: 100 Total Precip Applied to Facility: 145.611 Total Evap From Facility: 7.569 Discharge Structure Riser Height: 0.3333 ft. Precipitation applied to Riser Diameter: 24 in. facility 31,223 sf 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 0.716 0.000 0.000 0.000 0.0278 0.716 0.008 0.000 0.867 0.0556 0.716 0.015 0.000 0.867 0.0833 0.716 0.023 0.000 0.867 0.1111 0.716 0.031 0.000 0.867 0.1389 0.716 0.039 0.000 0.867 0.1667 0.716 0.047 0.000 0.867 0.1944 0.716 0.055 0.000 0.867 0.2222 0.716 0.063 0.000 0.867 0.2500 0.716 0.071 0.000 0.867 0.2778 0.716 0.079 0.000 0.867 0.3056 0.716 0.087 0.000 0.867 0.3333 0.716 0.095 0.000 0.867 0.3611 0.716 0.103 0.098 0.867 0.3889 0.716 0.111 0.278 0.867 0.4167 0.716 0.119 0.510 0.867 0.4444 0.716 0.127 0.785 0.867 0.4722 0.716 0.135 1.096 0.867 0.5000 0.716 0.143 1.438 0.867 0.5278 0.716 0.151 1.809 0.867 0.5556 0.716 0.159 2.205 0.867 0.5833 0.716 0.167 2.623 0.867 0.6111 0.716 0.175 3.060 0.867 0.6389 0.716 0.183 3.513 0.867 0.6667 0.716 0.191 3.979 0.867 0.6944 0.716 0.199 4.456 0.867 0.7222 0.716 0.207 4.940 0.867 0.7500 0.716 0.215 5.428 0.867 0.7778 0.716 0.223 5.917 0.867 0.8056 0.716 0.231 6.405 0.867 0.8333 0.716 0.238 6.888 0.867 0.8611 0.716 0.246 7.363 0.867 0.8889 0.716 0.254 7.827 0.867 0.9167 0.716 0.262 8.277 0.867 0.9444 0.716 0.270 8.712 0.867 0.9722 0.716 0.278 9.128 0.867 1.0000 0.716 0.286 9.523 0.867 1.0278 0.716 0.294 9.896 0.867 1.0556 0.716 0.302 10.24 0.867 1.0833 0.716 0.310 10.56 0.867 1.1111 0.716 0.318 10.86 0.867 1.1389 0.716 0.326 11.14 0.867 1.1667 0.716 0.334 11.38 0.867 1.1944 0.716 0.342 11.61 0.867 1.2222 0.716 0.350 11.81 0.867 1.2500 0.716 0.358 11.99 0.867 1.2778 0.716 0.366 12.16 0.867 1.3056 0.716 0.374 12.31 0.867 1.3333 0.716 0.382 12.59 0.867 1.3611 0.716 0.390 12.77 0.867 1.3889 0.716 0.398 12.94 0.867 1.4167 0.716 0.406 13.11 0.867 1.4444 0.716 0.414 13.28 0.867 1.4722 0.716 0.422 13.44 0.867 1.5000 0.716 0.430 13.60 0.867 1.5278 0.716 0.438 13.76 0.867 1.5556 0.716 0.446 13.92 0.867 1.5833 0.716 0.454 14.08 0.867 1.6111 0.716 0.461 14.24 0.867 1.6389 0.716 0.469 14.39 0.867 1.6667 0.716 0.477 14.54 0.867 1.6944 0.716 0.485 14.69 0.867 1.7222 0.716 0.493 14.84 0.867 1.7500 0.716 0.501 14.99 0.867 1.7778 0.716 0.509 15.14 0.867 1.8056 0.716 0.517 15.28 0.867 1.8333 0.716 0.525 15.43 0.867 1.8611 0.716 0.533 15.57 0.867 1.8889 0.716 0.541 15.71 0.867 1.9167 0.716 0.549 15.85 0.867 1.9444 0.716 0.557 15.99 0.867 1.9722 0.716 0.565 16.12 0.867 2.0000 0.716 0.573 16.26 0.867 2.0278 0.716 0.581 16.40 0.867 2.0556 0.716 0.589 16.53 0.867 2.0833 0.716 0.597 16.66 0.867 2.1111 0.716 0.605 16.79 0.867 2.1389 0.716 0.613 16.92 0.867 2.1667 0.716 0.621 17.05 0.867 2.1944 0.716 0.629 17.18 0.867 2.2222 0.716 0.637 17.31 0.867 2.2500 0.716 0.645 17.44 0.867 2.2778 0.716 0.653 17.56 0.867 2.3056 0.716 0.661 17.69 0.867 2.3333 0.716 0.669 17.81 0.867 2.3611 0.716 0.677 17.94 0.867 2.3889 0.716 0.684 18.06 0.867 2.4167 0.716 0.692 18.18 0.867 2.4444 0.716 0.700 18.30 0.867 2.4722 0.716 0.708 18.42 0.867 2.5000 0.716 0.728 18.54 0.867 ___________________________________________________________________ Name : Lateral I Basin 1 Bypass: No pavement tributuary to Impervious Land Use acre gravel area ROADS FLAT LAT 0.25 ___________________________________________________________________ Element Flows To: Outlet 1 Outlet 2 North Center Pervious ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.96 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.25 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.001102 5 year 0.00239 10 year 0.003834 25 year 0.006695 50 year 0.009894 100 year 0.014351 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.001 0.000 1950 0.002 0.000 1951 0.002 0.000 1952 0.001 0.000 1953 0.001 0.000 1954 0.005 0.000 1955 0.004 0.000 1956 0.001 0.000 1957 0.001 0.000 1958 0.001 0.000 1959 0.002 0.000 1960 0.001 0.000 1961 0.004 0.000 1962 0.001 0.000 1963 0.001 0.000 1964 0.003 0.000 1965 0.001 0.000 1966 0.001 0.000 1967 0.001 0.000 1968 0.001 0.000 1969 0.001 0.000 1970 0.001 0.000 1971 0.004 0.000 1972 0.001 0.000 1973 0.001 0.000 1974 0.002 0.000 1975 0.001 0.000 1976 0.002 0.000 1977 0.001 0.000 1978 0.001 0.000 1979 0.002 0.000 1980 0.001 0.000 1981 0.001 0.000 1982 0.001 0.000 1983 0.001 0.000 1984 0.001 0.000 1985 0.001 0.000 1986 0.007 0.000 1987 0.004 0.000 1988 0.001 0.000 1989 0.001 0.000 1990 0.001 0.000 1991 0.001 0.000 1992 0.001 0.000 1993 0.001 0.000 1994 0.001 0.000 1995 0.001 0.000 1996 0.009 0.000 1997 0.024 0.000 1998 0.001 0.000 1999 0.001 0.000 2000 0.001 0.000 2001 0.001 0.000 2002 0.001 0.000 2003 0.001 0.000 2004 0.001 0.000 2005 0.001 0.000 2006 0.026 0.000 2007 0.001 0.000 2008 0.001 0.000 2009 0.001 0.000 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0256 0.0000 2 0.0238 0.0000 3 0.0087 0.0000 4 0.0068 0.0000 5 0.0053 0.0000 6 0.0044 0.0000 7 0.0040 0.0000 8 0.0037 0.0000 9 0.0036 0.0000 10 0.0025 0.0000 11 0.0022 0.0000 12 0.0020 0.0000 13 0.0017 0.0000 14 0.0017 0.0000 15 0.0016 0.0000 16 0.0015 0.0000 17 0.0015 0.0000 18 0.0014 0.0000 19 0.0014 0.0000 20 0.0013 0.0000 21 0.0012 0.0000 22 0.0011 0.0000 23 0.0009 0.0000 24 0.0008 0.0000 25 0.0008 0.0000 26 0.0008 0.0000 27 0.0008 0.0000 28 0.0008 0.0000 29 0.0008 0.0000 30 0.0008 0.0000 31 0.0008 0.0000 32 0.0008 0.0000 33 0.0008 0.0000 34 0.0008 0.0000 35 0.0008 0.0000 36 0.0008 0.0000 37 0.0008 0.0000 38 0.0008 0.0000 39 0.0008 0.0000 40 0.0008 0.0000 41 0.0008 0.0000 42 0.0008 0.0000 43 0.0008 0.0000 44 0.0008 0.0000 45 0.0008 0.0000 46 0.0008 0.0000 47 0.0008 0.0000 48 0.0008 0.0000 49 0.0008 0.0000 50 0.0008 0.0000 51 0.0008 0.0000 52 0.0008 0.0000 53 0.0008 0.0000 54 0.0008 0.0000 55 0.0007 0.0000 56 0.0007 0.0000 57 0.0007 0.0000 58 0.0007 0.0000 59 0.0007 0.0000 60 0.0007 0.0000 61 0.0005 0.0000 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0006 2355 0 0 Pass 0.0006 1329 0 0 Pass 0.0007 438 0 0 Pass 0.0008 112 0 0 Pass 0.0009 103 0 0 Pass 0.0010 89 0 0 Pass 0.0011 77 0 0 Pass 0.0012 66 0 0 Pass 0.0013 61 0 0 Pass 0.0014 58 0 0 Pass 0.0015 54 0 0 Pass 0.0016 50 0 0 Pass 0.0017 49 0 0 Pass 0.0018 47 0 0 Pass 0.0019 43 0 0 Pass 0.0020 40 0 0 Pass 0.0021 36 0 0 Pass 0.0022 36 0 0 Pass 0.0022 32 0 0 Pass 0.0023 31 0 0 Pass 0.0024 31 0 0 Pass 0.0025 29 0 0 Pass 0.0026 29 0 0 Pass 0.0027 27 0 0 Pass 0.0028 26 0 0 Pass 0.0029 26 0 0 Pass 0.0030 26 0 0 Pass 0.0031 25 0 0 Pass 0.0032 23 0 0 Pass 0.0033 23 0 0 Pass 0.0034 23 0 0 Pass 0.0035 23 0 0 Pass 0.0036 23 0 0 Pass 0.0037 21 0 0 Pass 0.0038 19 0 0 Pass 0.0039 18 0 0 Pass 0.0039 17 0 0 Pass 0.0040 16 0 0 Pass 0.0041 16 0 0 Pass 0.0042 15 0 0 Pass 0.0043 15 0 0 Pass 0.0044 14 0 0 Pass 0.0045 13 0 0 Pass 0.0046 13 0 0 Pass 0.0047 13 0 0 Pass 0.0048 13 0 0 Pass 0.0049 13 0 0 Pass 0.0050 13 0 0 Pass 0.0051 13 0 0 Pass 0.0052 13 0 0 Pass 0.0053 13 0 0 Pass 0.0054 11 0 0 Pass 0.0055 11 0 0 Pass 0.0056 11 0 0 Pass 0.0056 11 0 0 Pass 0.0057 11 0 0 Pass 0.0058 11 0 0 Pass 0.0059 11 0 0 Pass 0.0060 11 0 0 Pass 0.0061 11 0 0 Pass 0.0062 11 0 0 Pass 0.0063 11 0 0 Pass 0.0064 11 0 0 Pass 0.0065 11 0 0 Pass 0.0066 10 0 0 Pass 0.0067 10 0 0 Pass 0.0068 9 0 0 Pass 0.0069 9 0 0 Pass 0.0070 8 0 0 Pass 0.0071 8 0 0 Pass 0.0072 8 0 0 Pass 0.0073 8 0 0 Pass 0.0073 8 0 0 Pass 0.0074 8 0 0 Pass 0.0075 8 0 0 Pass 0.0076 8 0 0 Pass 0.0077 8 0 0 Pass 0.0078 8 0 0 Pass 0.0079 8 0 0 Pass 0.0080 8 0 0 Pass 0.0081 8 0 0 Pass 0.0082 8 0 0 Pass 0.0083 8 0 0 Pass 0.0084 7 0 0 Pass 0.0085 7 0 0 Pass 0.0086 7 0 0 Pass 0.0087 7 0 0 Pass 0.0088 6 0 0 Pass 0.0089 6 0 0 Pass 0.0090 6 0 0 Pass 0.0090 6 0 0 Pass 0.0091 6 0 0 Pass 0.0092 6 0 0 Pass 0.0093 6 0 0 Pass 0.0094 6 0 0 Pass 0.0095 6 0 0 Pass 0.0096 6 0 0 Pass 0.0097 6 0 0 Pass 0.0098 5 0 0 Pass 0.0099 5 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 North Center Pervious POC N 169.70 N 99.99 Total Volume Infiltrated 169.70 0.00 0.00 99.99 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd 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 Â© by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. less than 4 inches Appendix C â€“ Runoff Treatment Stormwater Site Plan Appendix C Arlington Electrical Equipment &Pole Storage Yard July, 2016 8410 154th Avenue NE Redmond, Washington 98052 425.861.6000 August 16, 2016 Snohomish County PUD No. 1 Facilities Department 2323 California Street P.O. Box 1107 Everett, Washington 98206 Attention: Ben Davis, PE Subject: Custom Bioretention Soil Mix Proposed Pole Storage Yard Arlington Site Development Arlington, Washington File No. 0482-051-03 INTRODUCTION This letter contains the laboratory testing results and recommendations for a custom bioretention soil mix for use in the design and construction of the proposed Pole Storage Yard at the Districtâ€™s Arlington Site located between 172nd Street NE and 180th Street NE off of 59th Avenue NE in Arlington, Washington. GeoEngineers previously prepared a geotechnical report for the project titled, â€œGeotechnical Engineering Services, Proposed Pole Storage Yard, Arlington Site Development, Arlington, Washington,â€ dated May 4, 2016. Project Description We understand that a portion of the Arlington property is being developed for a Pole Storage Yard to store treated poles and transformers. Development of the pole storage yard will include constructing gravel laydown areas, asphalt paved access roads and transformer storage areas, and installation of a water line. We understand that the native soils do not meet the minimum requirements for treatment of stormwater infiltration at the site. In order to meet storm water guidelines, the District is looking at using an imported amended soil mix that will be placed below the pole storage yard surfacing gravel to improve treatment of stormwater infiltration. The amended material will need to support occasional truck traffic loads, therefore the Default Bioretention Soil Media (BSM) standard 60/40 compost soil mix (by volume) from the 2014 Stormwater Management Manual for Western Washington (SWMMWW) will not be sufficient from a structural support standpoint. Snohomish County PUD No. 1 | August 16, 2016 Page 2 Purpose and Scope The purpose of our engineering services is to develop a custom bioretention soil using a compost and gravel borrow mixture which will: (1) meet the 2014 SWMMWW requirements for a custom bioretention soil mix and (2) provide support for occasional truck traffic. CUSTOM BIORETENTION SOIL MIX REQUIREMENTS We understand that the 2014 SWMMWW allows for development of a custom bioretention soil mix. The SWMMWW lists the following criteria for a custom soil mix: â– Cation-exchange capacity (CEC) â‰¥ 5 milliequivalents/100 grams of dry soil; USEPA 9081. â– pH between 5.5 and 7.0. â– 5 to 8 percent organic matter content (by weight) before and after the saturated hydraulic conductivity test (ASTM D 2974). â– 2 to 5 percent fines passing the U.S. Standard No. 200 sieve â– Measured (initial) saturated hydraulic conductivity of less than 12 inches per hour; ASTM D 2434 (constant head) at 85 percent and 90 percent compaction (ASTM D 1557) as modified by Appendix V-B of the SWMMWW. â– Design (long-term) saturated hydraulic conductivity of more than 1 inch per hour. â– Compost to meet requirements of Volume V of the SWMMWW. SAMPLES FOR TESTING Gravel borrow and compost samples were collected from Lenz Enterprises, Inc. on June 15, 2016. Grain size analysis test results for the gravel borrow are presented in Appendix A. The borrow sample material meets the Washington State Department of Transportation (WSDOT) requirements for gravel borrow and is classified as a poorly graded sand with gravel with 4 percent passing the 200 sieve. The technical data sheet for the compost material that we received is presented in Appendix A (Figure A-1). File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 3 LABORATORY TESTING CEC Testing Cation Exchange Capacity (CEC) testing was performed following USEPA 9081 on a 5, 10, 15 and 20 percent compost to gravel borrow mix. The CEC test results are presented in Appendix A and are shown on the plot below. 10 9 8 7 6 5 4 3 CEC (meq/100grm) 2 1 0 0 5 10 15 20 25 Percent Compost by Weight pH Testing pH testing was performed on a 5, 10, 15 and 20 percent compost to gravel borrow mix. The pH test results are shown on the plot below. pH tests were also performed on the gravel borrow (pH = 6.1) and the compost (pH = 8.2) for baseline purposes. 10 9 8 7 6 pH5 4 3 2 1 0 0 5 10 15 20 25 Percent Compost by Weight File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 4 Organic Content Testing Organic content testing was performed following ASTM D 2974 on a 5, 10, 15 and 20 percent compost to gravel borrow mix prior to conducting the saturated hydraulic conductivity tests. One organic content test was performed on the 15 percent compost to gravel borrow mix following the saturated hydraulic conductivity test. The organic content test results are shown on the plot below. 10 9 8 7 6 5 4 3 2 Organic Content (percent)1 0 0 5 10 15 20 25 Percent Compost by Weight Before Hydraulic Conductivity Test After Hydraulic Conductivity Test Grain Size Analysis Grain size analysis testing was performed following ASTM D 6913 on the gravel borrow sample, the 10, 15 and 20 percent compost to gravel borrow mix. The grain size analysis test results are presented in Appendix A (Figure A-2). Proctor Testing Laboratory compaction testing was performed following ASTM D 1157 on the 10, 15 and 20 percent compost to gravel borrow mix designs. The laboratory compaction test results are presented in Appendix A (Figures A-3 through A-5) and the measured maximum dry density (MDD) test results are shown on the plot below. 128 126 124 122 120 118 116 114 112 110 108 Maximum Dry Density (pcf) 106 0 5 10 15 20 25 Percent Compost by Weight Uncorrected With Rock Correction File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 5 Saturated Hydraulic Conductivity Testing Saturated hydraulic conductivity testing was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 SWMMWW at 85 percent compaction (ASTM D 1557). The tests were completed on samples compacted at 85 and 90 percent of the MDD, respectively. The measured (initial) saturated hydraulic conductivity test results are presented in Appendix A (Figures A-6 through A-8) and are summarized on the plot below. 25 85% Compaction 20 90% Compaction 15 10 5 Measured (initial) saturated hydraulic conductivity (in/hour) 0 0 5 10 15 20 25 Percent Compost by Weight The 2014 SWMMWW recommends a factor of safety of 4.0 for the design hydraulic conductivity value. The design (long-term) saturated hydraulic conductivity values with an applied safety factor of 4.0 is shown in the plot below for the samples compacted at 85 and 90 percent of the MDD. 7 6 85% Compaction 90% Compaction 5 4 -term) saturated 3 2 1 Design (long hydraulic conductivity (in/hour) 0 0 5 10 15 20 25 Percent Compost by Weight CONCLUSIONS AND RECOMMENDATIONS Based on the results of the laboratory testing, the 15 percent compost to gravel borrow mix meets the requirements of the 2014 SWMMWW Design Criteria for Custom Bioretention Soil Mixes, with the exception of the pH values, which were slightly higher than the 7.0 maximum requirement. The pH of the tested File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 6 compost sample was 8.2. For the project specifications, we recommend compost with a pH between 5 and 7 be used for the bioretention soil mix in order to meet the SWMMWW design criteria. We recommend that the project specifications require gravel borrow be amended with 15 percent compost by weight for the custom bioretention soil mix below the gravel surfaced Pole Storage Yard. The gravel borrow should meet the requirements of section 9-03.14(1) of the 2016 WSDOT Standard Specifications. The compost should meet the requirements of the 2014 SWMMWW for bioretention. The materials should be adequately mixed to provide a uniform blended soil. The project specifications should require the contractor submit samples of their proposed custom bioretention soil mix for testing and verification purposes. GeoEngineers should test the submitted samples to confirm that the requirements of 2014 SWMMWW are satisfied (BMP T7.30, Design Criteria for Custom Bioretention Soil Mixes). A minimum 18-inch layer of the custom bioretention soil mix should be placed and compacted in areas designated for stormwater treatment. We recommend the bioretention soil mix be compacted in maximum 12 inch loose lifts to at least 85 percent of the MDD (corrected for gravel content) as determined by ASTM D 1557. This compaction effort is less than the standard of practice for support of traffic, therefore, periodic maintenance may be needed to repair rutting within the gravel surfacing if occasional vehicles are routed over these unpaved areas. The bioretention soil mix should not be placed below the asphalt or concrete paved areas of the site. In our opinion, a geotextile separation fabric is not needed above or below the bioretention gravel borrow mix, provided the bioretention soil is prepared as described above. The subgrade conditions and gravel surfacing recommendations provided in our May 4, 2016 geotechnical report should be followed. Although our proposed bioretention soil mix satisfies the 2014 SWMMWW design criteria for stormwater treatment, the structural capacity of the mix is limited because of the organic content and compaction criteria, and is not intended for support of significant equipment traffic. LIMITATIONS We have prepared this report for Snohomish County PUD No. 1. Copies of this report may be distributed to authorized agents and regulatory agencies as may be required for the project. Our evaluation pertains only to the physical properties of soil mechanics and hydrogeology as it pertains to the requirements of the 2014 SWMMWW design criteria. Chemical and treatment efficacy of the bioretention soil mix was not included in our scope of services. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. The conclusions, recommendations, and opinions presented in this report are based on our professional knowledge, judgment, laboratory test results, and experience. No warranty or other conditions, express or implied, should be understood. Any electronic form, facsimile or hard copy of the original document (email, text, table and/or figure), if provided, and any attachments should be considered a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record. File No. 0000-001-00 File No. 0482-051-03 APPENDIX A Laboratory Test Results 0482-051-03 Date Exported: 06/24/16 U.S. STANDARD SIEVE SIZE 3â€ 1.5â€ 3/4â€ 3/8â€ #4 #10 #20 #40 #60 #100 #200 100 90 80 70 60 PERCENT PASSING BY WEIGHT 50 40 30 20 10 0 Proposed Pole Storage Yard 1000 100 10 1 0.1 0.01 0.001 Sieve Analysis Results GRAIN SIZE IN MILLIMETERS Arlington, WA GRAVEL SAND COBBLES SILT OR CLAY COARSE FINE COARSE MEDIUM FINE Depth Moisture Symbol Sample (feet) (%) Soil Description No Compost N/A 5.4 Poorly graded sand with gravel (SP) Figure A 10% Compost N/A 8.0 Poorly graded sand with gravel and organic matter (SP) 15% Compost N/A 8.2 Poorly graded sand with silt and gravel and organic matter (SP-SM) 20% Compost N/A 12.1 Poorly graded sand with gravel and organic matter (SP) -2 Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they were performed,andshouldnotbe interpreted as representativeofanyothersamples obtained atother times,depthsorlocations,orgenerated by separate operationsorprocesses. Thegrainsizeanalysis results were obtained in general accordancewithASTMD6913. MOISTURE CONTENT (%) 0 5 10 15 20 25 30 140 135 130 125 (pcf) 120 DRY DENSITY 115 100% Saturation 110 (Gs=2.65) 105 100 Optimum Maximum Depth Moisture Dry Density Symbol Sample (feet) Soil Description (%) (pcf) Corrected 10% 9.9 127.1 N/A 10 Percent Compost/Gravel Borrow Mix Uncorrected Compost 13.5 116.0 Note: This report may not be reproduced, except in full, without written approval Compaction Test Results of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they were performed, and should not be interpreted as 10% Compost Mix representative of any other samples obtained at other times, depths or locations,orgenerated by separate operationsorprocesses. Proposed Pole Storage Yard The Proctor results were obtained in general accordance with Exported: 06/27/16 ASTMD1557. Arlington, WA Date -03 051 Figure A-3 0482- MOISTURE CONTENT (%) 0 5 10 15 20 25 30 140 135 130 125 (pcf) 120 DRY DENSITY 115 100% Saturation 110 (Gs=2.65) 105 100 Optimum Maximum Depth Moisture Dry Density Symbol Sample (feet) Soil Description (%) (pcf) Corrected 15% 9.1 126.0 N/A 15 Percent Compost/Gravel Borrow Mix Uncorrected Compost 12.5 114.0 Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific Compaction Test Results sample on which they were performed, and should not be interpreted as 15% Compost Mix representative of any other samples obtained at other times, depths or locations,orgenerated by separate operationsorprocesses. Proposed Pole Storage Yard The Proctor results were obtained in general accordance with Exported: 06/30/16 ASTMD1557. Arlington, WA Date -03 051 Figure A-4 0482- MOISTURE CONTENT (%) 0 5 10 15 20 25 125 120 100% 115 Saturation (Gs=2.65) (pcf) 110 DRY DENSITY 105 100 95 Optimum Maximum Depth Moisture Dry Density Symbol Sample (feet) Soil Description (%) (pcf) Corrected 20% 10.6 120.0 Grab Poorly graded sand with gravel and organic matter (SP) Uncorrected Compost 13.7 109.6 Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific Compaction Test Results sample on which they were performed, and should not be interpreted as 20% Compost Mix representative of any other samples obtained at other times, depths or locations,orgenerated by separate operationsorprocesses. Proposed Pole Storage Yard The Proctor results were obtained in general accordance with Exported: 07/08/16 ASTMD1557. Arlington, WA Date -03 051 Figure A-5 0482- Boring #: N/A Sample #: 10% Mix Depth: N/A Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 116.0 Optimum Moisture Content (%) 13.5 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 85.0 Sample Prepared Moisture Content (%) 13.5 Sample length (in): 8.00 (cm): 20.32 (L) Remolded Compaction (%) 85.3 Sample volume (in3): 226.19 (cm3): 3707.33 Sample Back Calculated After Test 86.4 Compaction (%) Sample volume (ft3): 0.1309 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 80.00 81.00 1.00 15.2 50.0 233 1.18E-03 0.066 1.79E-02 22.0 0.9547 1.70E-0224.1 2 80.00 81.00 1.00 15.2 50.0 234 1.17E-03 0.066 1.78E-02 22.0 0.9547 1.70E-0224.0 3 80.00 81.00 1.00 15.2 50.0 232 1.18E-03 0.066 1.80E-02 22.0 0.9547 1.71E-0224.2 4 80.00 81.00 1.00 15.2 50.0 233 1.18E-03 0.066 1.79E-02 22.0 0.9547 1.70E-0224.1 avg 1.79E-02 1.70E-02 24.1 1 80.00 81.00 1.00 15.2 100.0 469 1.17E-03 0.066 1.78E-02 22.0 0.9547 1.69E-02 24.0 2 80.00 81.00 1.00 15.2 100.0 473 1.16E-03 0.066 1.76E-02 22.0 0.9547 1.68E-02 23.8 3 80.00 81.00 1.00 15.2 100.0 473 1.16E-03 0.066 1.76E-02 22.0 0.9547 1.68E-02 23.8 4 80.00 81.00 1.00 15.2 100.0 471 1.16E-03 0.066 1.77E-02 22.0 0.9547 1.69E-02 23.9 5 80.00 81.00 1.00 15.2 100.0 473 1.16E-03 0.066 1.76E-02 22.1 0.9524 1.67E-02 23.7 6 80.00 81.00 1.00 15.2 250.0 1207 1.14E-03 0.066 1.73E-02 22.1 0.9524 1.64E-02 23.2 avg 1.76E-02 1.67E-02 23.7 Total avg 1.77E-02 1.69E-02 23.9 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 10% Compost Mix at 85% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-6 Manual for Western Washington (SWMMWW). Boring #: 10% Compost Sample #: 10% Mix (2) Depth: Grab Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 116.0 Sample area (in2): 28.274 (cm2): 182.43 (A) Optimum Moisture Content (%) 13.5 Target Relative Density (%) 90.0 Sample length (in): 9.00 (cm): 22.86 (L) Sample Prepared Moisture Content (%) 13.5 3 3 Remolded Compaction (%) 90.3 Sample volume (in): 254.47 (cm ): 4170.75 Sample Back Calculated After Test 90 Sample volume (ft3): 0.1473 Compaction (%) Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 79.50 81.80 2.30 15.2 10.0 117 4.69E-04 0.151 3.10E-03 19.4 1.0169 3.14E-034.5 2 79.50 81.80 2.30 15.2 10.0 121 4.53E-04 0.151 2.99E-03 19.4 1.0169 3.04E-034.3 3 79.50 81.80 2.30 15.2 10.0 119 4.61E-04 0.151 3.04E-03 19.4 1.0169 3.09E-034.4 4 79.50 81.80 2.30 15.2 10.0 112 4.89E-04 0.151 3.23E-03 19.4 1.0169 3.28E-034.7 5 79.50 81.80 2.30 15.2 20.0 217 5.05E-04 0.151 3.34E-03 19.4 1.0169 3.39E-034.8 6 79.50 81.80 2.30 15.2 20.0 210 5.22E-04 0.151 3.45E-03 19.5 1.0144 3.49E-035.0 avg 3.19E-03 3.24E-03 4.6 7 79.50 81.80 2.30 15.2 20.0 205 5.35E-04 0.151 3.53E-03 19.5 1.0144 3.58E-035.1 8 79.50 81.80 2.30 15.2 20.0 214 5.12E-04 0.151 3.39E-03 19.5 1.0144 3.43E-034.9 9 79.50 81.80 2.30 15.2 20.0 211 5.20E-04 0.151 3.43E-03 19.5 1.0144 3.48E-034.9 10 79.50 81.80 2.30 15.2 40.0 436 5.03E-04 0.151 3.32E-03 19.4 1.0169 3.37E-034.8 11 79.50 81.80 2.30 15.2 40.0 449 4.88E-04 0.151 3.23E-03 19.4 1.0169 3.28E-034.6 12 79.50 81.80 2.30 15.2 40.0 449 4.88E-04 0.151 3.23E-03 19.4 1.0169 3.28E-034.6 13 79.50 81.80 2.30 15.2 40.0 455 4.82E-04 0.151 3.18E-03 19.4 1.0169 3.23E-034.6 avg 3.33E-03 3.37E-03 4.8 14 79.50 81.80 2.30 15.2 40.0 478 4.59E-04 0.151 3.03E-03 19.3 1.0195 3.08E-034.4 15 79.50 81.80 2.30 15.2 40.0 469 4.68E-04 0.151 3.09E-03 19.2 1.0220 3.15E-034.5 16 79.50 81.80 2.30 15.2 40.0 479 4.58E-04 0.151 3.03E-03 19.2 1.0220 3.09E-034.4 avg 3.05E-03 3.11E-03 4.4 Total avg 3.19E-03 3.24E-03 4.6 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 10% Compost Mix at 90% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-7 Manual for Western Washington (SWMMWW). Constant Head Hydraulic Conductivity Test Project: Arlington Pole Storage Yard Date: 6/28/16 Project #: 0482-051-03 Tested by: S. Swenson Boring #: N/A Sample #: 15% Mix Depth: N/A Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 114.0 Optimum Moisture Content (%) 12.5 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 85.0 Sample Prepared Moisture Content (%) 13.0 Sample length (in): 9.00 (cm): 22.86 (L) Remolded Compaction (%) 84.5 Sample volume (in3): 254.47 (cm3): 4170.75 Sample Back Calculated After Test 91.2 Compaction (%) Sample volume (ft3): 0.1473 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 80.60 81.60 1.00 15.2 10.0 212 2.59E-04 0.066 3.93E-03 20.7 0.9850 3.86E-035.5 2 80.60 81.60 1.00 15.2 10.0 215 2.55E-04 0.066 3.88E-03 20.7 0.9850 3.81E-035.4 3 80.60 81.60 1.00 15.2 10.0 219 2.50E-04 0.066 3.80E-03 20.7 0.9850 3.74E-035.3 4 80.60 81.60 1.00 15.2 10.0 210 2.61E-04 0.066 3.97E-03 20.7 0.9850 3.90E-035.5 5 80.60 81.60 1.00 15.2 10.0 209 2.62E-04 0.066 3.99E-03 20.7 0.9850 3.92E-035.6 6 80.60 81.60 1.00 15.2 10.0 209 2.62E-04 0.066 3.99E-03 21.1 0.9755 3.88E-035.5 7 80.60 81.60 1.00 15.2 10.0 215 2.55E-04 0.066 3.88E-03 21.2 0.9732 3.76E-035.3 avg 3.92E-03 3.84E-03 5.4 1 80.60 81.60 1.00 15.2 20.0 421 2.60E-04 0.066 3.96E-03 21.0 0.9779 3.86E-035.5 2 80.60 81.60 1.00 15.2 20.0 401 2.73E-04 0.066 4.16E-03 20.7 0.9850 4.09E-035.8 3 80.60 81.60 1.00 15.2 20.0 440 2.49E-04 0.066 3.79E-03 20.7 0.9850 3.72E-035.3 4 80.60 81.60 1.00 15.2 20.0 423 2.59E-04 0.066 3.94E-03 21.0 0.9779 3.84E-035.4 avg 3.96E-03 3.88E-03 5.5 Total avg 3.94E-03 3.86E-03 5.5 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 15% Compost Mix at 85% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-8 Manual for Western Washington (SWMMWW). Boring #: Sample #: 15% Mix Depth: Grab Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 114.0 Optimum Moisture Content (%) 12.5 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 90.0 Sample Prepared Moisture Content (%) 12.5 Sample length (in): 9.00 (cm): 22.86 (L) Remolded Compaction (%) 90 Sample volume (in3): 254.47 (cm3): 4170.75 Sample Back Calculated After Test 90.2 Compaction (%) Sample volume (ft3): 0.1473 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 80.20 81.90 1.70 15.2 10.0 393 1.39E-04 0.112 1.25E-03 19.3 1.0195 1.27E-031.8 2 80.20 81.90 1.70 15.2 10.0 408 1.34E-04 0.112 1.20E-03 19.2 1.0220 1.23E-031.7 3 80.20 81.90 1.70 15.2 10.0 393 1.39E-04 0.112 1.25E-03 19.2 1.0220 1.27E-031.8 4 80.20 81.90 1.70 15.2 10.0 374 1.47E-04 0.112 1.31E-03 19.2 1.0220 1.34E-031.9 5 80.20 81.90 1.70 15.2 10.0 382 1.43E-04 0.112 1.28E-03 19.2 1.0220 1.31E-031.9 6 80.20 81.90 1.70 15.2 10.0 380 1.44E-04 0.112 1.29E-03 19.2 1.0220 1.32E-031.9 7 80.20 81.90 1.70 15.2 10.0 374 1.47E-04 0.112 1.31E-03 19.2 1.0220 1.34E-031.9 8 80.20 81.90 1.70 15.2 10.0 372 1.47E-04 0.112 1.32E-03 19.2 1.0220 1.34E-031.9 9 80.20 81.90 1.70 15.2 10.0 377 1.45E-04 0.112 1.30E-03 19.2 1.0220 1.33E-031.9 10 80.20 81.90 1.70 15.2 10.0 367 1.49E-04 0.112 1.34E-03 19.2 1.0220 1.36E-031.9 11 80.20 81.90 1.70 15.2 10.0 369 1.49E-04 0.112 1.33E-03 19.2 1.0220 1.35E-031.9 12 80.20 81.90 1.70 15.2 10.0 371 1.48E-04 0.112 1.32E-03 19.2 1.0220 1.35E-031.9 avg 1.29E-03 1.32E-03 1.9 1 80.20 81.90 1.70 15.2 67.0 2442 1.50E-04 0.112 1.34E-03 21.0 0.9779 1.31E-03 1.9 2 80.20 81.90 1.70 15.2 114.0 4029 1.55E-04 0.112 1.39E-03 20.7 0.9850 1.36E-03 1.9 avg 1.37E-03 1.34E-03 1.9 Total avg 1.33E-03 1.33E-03 1.9 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 15% Compost Mix at 90% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-9 Manual for Western Washington (SWMMWW). Constant Head Permeability Test data Project: Arlington Pole Storage Yard Date: 6/28/16 Project #: 0482-051-03 Tested by: S. Swenson Boring #: N/A Sample #: 20% Mix Depth: N/A Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 109.6 Optimum Moisture Content (%) 13.7 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 85.0 Sample Prepared Moisture Content (%) 13.7 Sample length (in): 9.00 (cm): 22.86 (L) Remolded Compaction (%) 84.7 Sample volume (in3): 254.47 (cm3): 4170.75 Sample Back Calculated After Test 85.4 Compaction (%) Sample volume (ft3): 0.1473 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 79.90 81.90 2.00 15.2 5.0 176 1.56E-04 0.132 1.18E-03 20.8 0.9826 1.16E-03 1.6 2 79.90 81.90 2.00 15.2 5.0 185 1.48E-04 0.132 1.13E-03 20.9 0.9803 1.10E-03 1.6 3 79.90 81.90 2.00 15.2 5.0 158 1.73E-04 0.132 1.32E-03 20.8 0.9826 1.29E-03 1.8 4 79.90 81.90 2.00 15.2 5.0 154 1.78E-04 0.132 1.35E-03 20.9 0.9803 1.32E-03 1.9 5 79.90 81.90 2.00 15.2 5.0 153 1.79E-04 0.132 1.36E-03 20.9 0.9803 1.33E-03 1.9 avg 1.26E-03 1.24E-03 1.8 1 79.90 81.90 2.00 15.2 10.0 350 1.57E-04 0.132 1.19E-03 21.0 0.9779 1.16E-031.6 2 79.90 81.90 2.00 15.2 10.0 337 1.63E-04 0.132 1.24E-03 20.9 0.9803 1.21E-031.7 3 79.90 81.90 2.00 15.2 10.0 338 1.62E-04 0.132 1.23E-03 21.1 0.9755 1.20E-031.7 4 79.90 81.90 2.00 15.2 10.0 342 1.60E-04 0.132 1.22E-03 21.0 0.9779 1.19E-031.7 5 79.90 81.90 2.00 15.2 10.0 340 1.61E-04 0.132 1.23E-03 21.1 0.9755 1.19E-031.7 6 79.90 81.90 2.00 15.2 10.0 335 1.64E-04 0.132 1.24E-03 21.1 0.9755 1.21E-031.7 7 79.90 81.90 2.00 15.2 10.0 337 1.63E-04 0.132 1.24E-03 21.1 0.9755 1.20E-031.7 8 79.90 81.90 2.00 15.2 10.0 341 1.61E-04 0.132 1.22E-03 21.1 0.9755 1.19E-031.7 9 79.90 81.90 2.00 15.2 10.0 336 1.63E-04 0.132 1.24E-03 21.2 0.9732 1.20E-031.7 10 79.90 81.90 2.00 15.2 10.0 339 1.62E-04 0.132 1.23E-03 21.2 0.9732 1.19E-031.7 avg 1.23E-03 1.20E-03 1.7 Total avg 1.25E-03 1.22E-03 1.7 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 20% Compost Mix at 85% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-10 Manual for Western Washington (SWMMWW). Appendix D â€“ Well Head Protection Zones Stormwater Site Plan Appendix D Arlington Electrical Equipment &Pole Storage Yard July, 2016 Haller Park Wellfield 4 3 2 1 6 9 10 11 12 7 16 15 14 13 18 Airport Well Project Site 21 22 23 24 19 Area of project site being developed. 28 27 26 25 30 33 34 35 36 31 FIGURE 1 Wells 1-Year-Buffer Wellhead Protection Zone 5-Year 6-Month 5-Year-Buffer WELLHEAD PROTECTION ZONES 6-Month-Buffer 10-Year 1-Year 10-Year-Buffer CITY OF ARLINGTON Feet 0 2,000 Appendix E â€“ Soil Map Stormwater Site Plan Appendix E Arlington Electrical Equipment &Pole Storage Yard July, 2016 Hydrologic Soil Groupâ€”Snohomish County Area, Washington (Arlington Temporary Storage Yard) 122Â° 9' 12'' 122Â° 8' 19'' 563000 563100 563200 563300 563400 563500 563600 563700 563800 563900 564000 48Â° 9' 35'' 48Â° 9' 35'' 5334400 5334400 180th St 59th Dr Bovee Ln 5334300 5334300 Upland Dr 72 5334200 5334200 74 18 5334100 Hillside Ct 5334100 30 39 59th Ave 5334000 5334000 5333900 5333900 67th Ave Highland View Dr 5333800 5333800 5333700 5333700 48Â° 9' 11'' 48Â° 9' 11'' 563000 563100 563200 563300 563400 563500 563600 563700 563800 563900 564000 Map Scale: 1:5,280 if printed on A size (8.5" x 11") sheet. Meters 122Â° 9' 13'' 0 50 100 200 300 122Â° 8' 19'' Feet 0 250 500 1,000 1,500 Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 1 of 4 Hydrologic Soil Groupâ€“Snohomish County Area, Washington (Arlington Temporary Storage Yard) MAP LEGEND MAP INFORMATION Area of Interest (AOI) Map Scale: 1:5,280 if printed on A size (8.5" Ã— 11") sheet. Area of Interest (AOI) The soil surveys that comprise your AOI were mapped at 1:24,000. Soils Soil Map Units Warning: Soil Map may not be valid at this scale. Soil Ratings Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line A placement. The maps do not show the small areas of contrasting A/D soils that could have been shown at a more detailed scale. B Please rely on the bar scale on each map sheet for accurate map B/D measurements. C Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov C/D Coordinate System: UTM Zone 10N NAD83 D This product is generated from the USDA-NRCS certified data as of Not rated or not available the version date(s) listed below. Political Features Soil Survey Area: Snohomish County Area, Washington Cities Survey Area Data: Version 7, Jun 29, 2012 Water Features Date(s) aerial images were photographed: 7/24/2006 Streams and Canals The orthophoto or other base map on which the soil lines were Transportation compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting Rails of map unit boundaries may be evident. Interstate Highways US Routes Major Roads Local Roads Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 2 of 4 Hydrologic Soil Groupâ€“Snohomish County Area, Washington Arlington Temporary Storage Yard Hydrologic Soil Group Hydrologic Soil Groupâ€” Summary by Map Unit â€” Snohomish County Area, Washington (WA661) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 18 Everett gravelly sandy loam, 8 A 5.4 6.8% to 15 percent slopes 30 Lynnwood loamy sand, 0 to 3 A 61.2 76.7% percent slopes 39 Norma loam B/D 12.5 15.7% 72 Tokul gravelly loam, 0 to 8 C 0.3 0.3% percent slopes 74 Tokul gravelly loam, 15 to 25 C 0.3 0.4% percent slopes Totals for Area of Interest 79.8 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Groupâ€“Snohomish County Area, Washington Arlington Temporary Storage Yard Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 4 of 4 Appendix F â€“ Operations and Maintenance Manual Stormwater Site Plan Appendix F Arlington Electrical Equipment &Pole Storage Yard July, 2016 Drip pan NOT TO SCALE Figure IV-2.2.2 Drip Pan Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. Drip pan within rails NOT TO SCALE Figure IV-2.2.3 Drip Pan Within Rails Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.4 Loading Dock with Door Skirt Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.5 Loading Dock with Overhang Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.8 Secondary Containment System Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. Lid NOT TO SCALE Figure IV-2.2.9 Locking System for Drum Lid Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.10 Covered and Bermed Containment Area Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. *Note that the secondary containment is not shown in this figure NOT TO SCALE Figure IV-2.2.11 Mounted Container - with Drip Pan Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.13 Covered Storage Area for Bulk Solids (include berm if needed) D E P A R T M E N T O F Revised December 2015 ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.14 Material Covered with Plastic Sheeting Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. PWC- Arlington Electrical Equipment and Pole Yard Contractor: PELLCO Construction, Inc Submittal No. 004 Date: 11/17/2016 Resubmittal: Previous Submittal No: This section to be completed by Contractor For District Use Item No. P/C Spec. Paragraph Contractor's Cat. or Dwg. No. Description of Item Copies of Subm. Reviewed By Notes 1 334111 Water Products 1 Submittal Review: By Date Initial Review By: Cody A. Bye 11/17/2016 Substitution: (Per Section 01010, 1.12) Remarks. Engineering Design Review Final Review Returned to Contractor HD Fowler Company Submittal -Water Sec. 15: Ln 29 Vendor: 85870 TYTON JDlNTÂ® PIPE Each ofthe following is a nationally recognized standards organization; ANSI/AWWA C151/A2l.5, Ductile Iron Pipe, Centrifugally Cast forWater. I American National Standards Institute (ANSI) American WaterWorks Association (A\/IANA) Ductile Iron TYTON JOINT Pipe is centrifu- American SocietyforTesting and Materials (ASTM) gally cast in metal molds in accordance Underwriters Laboratories (UL) with ANSI/AWWA C151/A21.5. National Fire Protection Association (NFPA) National Sanitation Foundation (NSF) The asphaltic outside coating is in accor- Factory Mutual (FM) dance with ANSI/AWWA C151/A21.51. As specified in ANSI/AWWA C151/A21.51, TYTON JOINT is U.S. Pipeâ€™s trademark for pipe with a push-on type connection. Simplicity, sturdiness pipe weights have been calculated using and watertightness are built into the system by design. Convincing proof of its worldwide acceptance standard barrel weights and weights of is shown bythe fact that more than 95% ofthe pipe now sold by U.S. Pipe is TYTON JOINT Pipe. bells being produced. TYTON JOINT Pipe is available in sizes 3" through 64". Sizes 3" through 42" are available in nominal ANSI/AWWA C104/A21.4, Cement-Mortar 18-foot laying lengths. 4â€œ through 30â€œ sizes, along with sizes 48" through 64", are available in Lining For Ductile-Iron Pipe and Fittings nominal 20-foot laying lengths. For Water. The cement-mortar lining and inside TYTONJOINT Pipe in sizes 4â€œ through 36" are UL Listed, and sizes 4" through 16" are FM Approved. coating are in accordancewith ANSI/AWWA When TYTON JOINT Pipe is used for bridge crossings or other above-ground installations, each length C104/A21/I. of pipe must be supported in a mannerto restrict both vertical and horizontal movement. Special linings and/orcoatings can be furnished for specific conditions. ATYTONÂ® Gasket is the only accessory required when installing TYTON JOINT Pipe. It is a circular rubber gasket that has a modified bulb shape in cross section. Gaskets are furnished in accordance ANSI/AWWA C111/A2l.ll, Rubber-Gasket with ANSI/AWWA C111/A21.1. Composition and dimensions of the gasket have been carefully Joints for Ductile-Iron Pressure Pipe engineered to ensure a watertight and lasting seal. The standard TYTON Gasket is manufactured of and Fittings. SBR â€” styrene butadiene rubber. Gaskets of special elastomers may be ordered for special TYTONÂ® Gaskets are furnished in accor- applications. The gasket contour and bell socket contour ensure that the gasket will remain seated dance with ANSI/AWWA C111/A21.11. during proper assembly of the pipe. When joint restraint is required for push-on joint pipe, two options are available from U.S. Pipe. Forjoint restraint of 4" through 24", FIELD LOK 350Â® Gaskets ANSI/AWWA C105/A21.5, Polyethylene may be used. FIELD LOK 350 Gaskets are rated for 350 psi in sizes 4" through 24". In addition, for 4" Encasement for Ductile Iron Pipe through 36" sizes, TR FLEX Pipe and Fittings may be used, and for 30" through 64" sizes, HP LOKÂ® Systems. Pipe and Fittings may be used. TR FLEX Pipe and Fittings are rated forworking pressures for 350 psi If specifiers and users believe that corro- in 4" through 24" sizes, 250 psi in sizes 30â€œ through 36". For HP LOK Pipe and Fittings, the working sive soils will be encountered where our pressure is 350 psi for 30" through 64". For higher pressure applications contact your U.S. Pipe products are to be installed, please refer representative. Complete details on FIELD LOK 350 Gaskets, TR FLEX Pipe and Fittings, and HP LOK to ANSI/AWWA C105/A21.5, for proper external protection procedures. Pipe and Fittings can be found on our website, www.uspipe.com. NOTE; U.S. Pipequalifies forFederalProcurementunderPublicLawNo. 94-580, Section 6002, knownas the ASTM A746-D3 "Standard specification ResourceRecoveryActof1976, since, due to modern technology, recyclediron andsteelscrapareusedtoa for Ductile Iron Gravity Sewer Pipe." largedegreeinourDuctileIronPipeproduction. Theplainendofthepipeisfurnishedbeveledorwithaquarterellipseontheedgetoallowassembly. Morethan40 ASTM A716-D8 "Standard Specification yearsofsuccessfulexperiencehaveproveditssealingcapabilities. Hydrostatictestshaveshown thatthesystem for Ductile Iron Culvert Pipe." willwithstandpressures farin excessofratedpressures. ASTM A536 "Standard Specification for TYTONÂ®, TYTONl0lNTÂ®, TR FLFXÂ®, HPLOKÂ®andFIELD LOK350Â® are Registered Trademarks of U.S. Pipe andFoundryCompany LLC. Ductile Iron Castings." REVISED 41816 HD Fowler Company Submittal -Water Sec. 15: Ln 29 Vendor: 85870 PRESSURE CLASS â€” THICKNESSES, DIMENSIONS AND WEIGHT 18-FOOT LAYING LENGTH 20-FOOT LAYING LENGTH OUTSIDE BARREL WEIGHT WEIGHT PER WEIGHT PER SIZE THICKNESS THICKNESS DIAMETER* PER FOOT LENGTHt LENGTHT Inches CLASS Inches Inches Pounds Pounds Pounds 3.00 11.8 220 â€” 3.00 12.8 240 â€” (:1(:100.|>Q0CD\l-I> 3.00 13.7 255 â€” CD-5O0O0 0.20 4.30 11.3 215 235 4 0.20 4.30 12.6 235 260 4 LTILTI00|\DO3|â€”\-I>LTIU"lLTILTILTI 0.32 4.30 13.8 260 285 4 54 0.35 4.30 15.0 280 310 4 55 0.33 4.30 16.1 300 330 4 50 0.41 4.30 17.3 320 355 0 50 0.25 0.00 16.0 305 335 0 51 0.23 0.00 17.8 335 370 52 0.31 0.00 19.6 370 410 53 0.34 0.00 21.4 400 445 54 0.37 0.00 23.2 435 480 55 0.40 0.00 25.0 465 515 Oâ€˜-DOâ€˜-iO'JO'JO'J 50 0.43 0.00 26.7 495 550 3 50 0.27 0.05 22.8 430 475 3 51 0.30 0.05 25.2 475 525 52 0.33 0.05 27.7 520 575 53 0.30 0.05 30.1 560 620 54 0.30 0.05 32.5 605 670 55 0.42 0.05 34.8 650 720 XXXXX 50 0.45 0.05 37.2 690 765 NOTE: Thicknesses anddimensions of3"through 64"ductile ironpipe conform toANS///IWI/llA C151/7421.51. Weights mayvaryfrom the standardbecause ofdifferences in be/I weights. *To/erance of0.D. ofspigotend; 3-12in., 10.06in.,- 14-24 in., +0.05in., -0.08in.; 30-48in., +0.08in., -0.06in.,- 54-64 in., +0.04 in., -0.10 in. T Includingbe/I; calculated weightofpipe roundedoffto nearest5lbs. Table continued on next page. H 115010511.-1 1e.15 Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal-Water Sec. 20: Ln 38 Vendor: 85870 THICKNESS CLASS â€” THICKNESSES, DIMENSIONS AND WEIGHT (cont.) 18-FOOTLAYING LENGTH 20-FOOT LAYING LENGTH OUTSIDE BARREL WEIGHT WEIGHT PER WEIGHT PER SIZE THICKNESS THICKNESS DIAMETER* PER FOOT LENGTHt LENGTHT Inches CLASS Inches Inches Pounds Pounds Pounds â€˜: 50 0.20 1; 30.1 570 630 : 51 0.32 -- 33.2 625 690 : 52 0.35 -- 36.2 680 750 : 53 0.33 -- 39.2 730 810 : 54 0.41 -- 42.1 785 870 : 0.44 -- 45.1 840 930 la 48.0 890 990 my u ......_.u '2 :1.1:1 _ 5:1:1 38.4 725 800 Q0-|>g]H '591â€˜ '2 0.34 13.20 42.0 790 875 '2 0.37 13.20 45.6 855 945 '2 0'10'1O0l\)CD|â€”\U"lO5L71LTIL710'1 0.40 13.20 49.2 920 1015 '2 54 0.43 13.20 52.8 985 1090 '2 55 0.46 13.20 56.3 1045 1160 '2 56 0.49 13.20 59.9 1110 1230 u ... u 47.5 910 1005 0.30 15.30 51.7 985 1090 0.30 15.30 55.9 1060 1170 0.42 15.30 60.1 1135 1255 U -- U 64.2 1210 1340 U â€” U 68.4 1285 1420 LLLLLLL 72.5 1360 1505 u _- u J 55.8 1065 1175 U -- U ' 0.37 17.40 60.6 1150 1275 ' 0.40 17.40 65.4 1240 1370 ' 0.43 17.40 70.1 1325 1465 J 74.9 1410 1560 u ... u J 79.7 1495 1655 U -- U J :1:1:1:1:1:1:1:1 :1:1:1:1:1:1:1:1 84.4 1580 1750 Oâ€˜)-5O1-5Oâ€˜)-5Oâ€˜)-5O1Oâ€˜)-5Oâ€˜)-5-5 U1U"IO000CD|\>3|\)lâ€”*1â€”\-I>U1U"IO5U1U1U1U1U1U1U1U1U1U1L71 U CA.)O0LJTI-I>l\DO0Q0LOUâ€˜lIi-I>O3 â€”S->"'.\'9"â€˜Q0-I?.\'S->"'09U-I?.\'Q99"â€˜-I?.\'09-I? NOTE: Thicknesses anddimensions of3"through 64"ductile ironpipe conform toANSI/AWWA C151/421.51. Weights may varyfrom thestandardbecause ofdifferences in bell weights. *To/erance of0.D. ofspigotend.- 3-12in., :0.06 in.,- 14-24 in., +0.05in., -0.08in.,- 30-48in., +0.08in., -0.06in.,- 54-64 in., +0.04 in., -0.10in. f Includingbell; calculated weightofpipe roundedoffto nearest5lbs. Table continued on next page. : 115010511.-1 1e.15 Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal-Water Sec. 20: Ln 39 Vendor: 85870 . .,.._,4.. FIELD LOK 350Â® GASKET i Certiï¬edto P3 866DIPPIPE ANSI/NSF61 FIELD LOK 350Â® Gasket Restrained joint pipe and fittings are used in pressurized Ductile Iron pipelines to prevent the joints ofthe line from separating due to thrust forces. Thrust forces generally occur at changes of ANSI/AWWA G111/A21.1I Standard for direction in the line. Usually, a calculated length of pipeline extending from the location of Rubber-Gasket Joints for Ductile Iron the thrust force is restrained in the joints so that this force can be transmitted to the soil Pressure Pipe and Fittings. surrounding the line. The entire pipeline is often restrained for installations in poor soil orfor crit- ical lines. FIELD LOK 350 Gaskets are available in 4"â€”24â€œ sizes and the pressure rating is U.S. Pipeâ€™s FIELD LOK350 Gasket has proven to be an extremely successful, trouble-free means based on the performance requirements ofjoint restraint forwell over one million Ductile Iron pipe and fitting joint assemblies across of ANSI/AWWA C111/A21.11. North America. By simply inserting a FIELD LOK350 Gasket into the socket of a TYTON JOlNTÂ® Pipe, Fitting orValve, restraint is instantly achieved when the joint is assembled. Stainless steel locking segments vulcanized into the FIELD LOK350 Gasket grip the pipe to prevent joint separation. FIELD LOK 350 Gaskets, utilizing patented improvements, are rated by U.S. Pipe for operating pressures up to 350 psi â€” a rating that now matches that of Pressure Glass 350 pipe â€” giving the engineer and user new flexibility in designing piping systems. Q Underwriters Laboratories lists the 4"â€”24" sizes for 350 psi. Factory Mutual, utilizing a safety factor of 4, approves the 4"â€”16" sizes for 250 psi and the 18"â€”24" sizes for 200 psi service. With the use ofthe FIELD LOK 350 Gasket, push-on joint Ductile Iron TYTON JOINT Pipe or Fittings can be quickly and securely restrained as thejoint is assembled. The restraint provided shall be a boltless, integral restraining system and shall be rated for 350 psi in accordance with the per- formance requirements ofANSI/AWWA C111/A21.11. Field cut pipe are no longer a problem to restrain. No pipe surface preparation* or grooving is required forfield cut pipe otherthan the cut end needing to be beveled as required for any push-on joint spigot end. With the FIELD LOK350 Gasket in place, thejoints are restrained without thrust blocks, bolts, grooves, rods, clamps or retainer glands, resulting in savings of labor, material and time. CAUTION: U.S. Pipe does notrecommendFIELDLOK350 Gaskets foruseaboveground. The /ong-term effectofcyclicalmovements can begradualjointseparation to thepointthattheseal on thegasketbulb is compromised. Sources ofcyclicalmovements include vibration as maybe foundon bridgecrossings, andthermalexpansion andcontraction resultingfrom atmospheric temperature changes. These conditions arenotexperienced with buriedpipelines. *Seenote onpage 5regardingpipe with thickcoatings ortape wrap. FIELDLOKÂ®, FIELDLOK350Â®, TYTONÂ®, TYTON/0/NTÂ® and TRFLEXÂ® areRegistered Trademarks ofU.S. PipeandFoundryCompany. NDTE: ifspecifiers andusersbelieve thatcorrosive soils willbe encountered whereproducts are tobe installed, pleaserefertoANS//AWW4 C105/A21.5 Polyethylene Encasement for Ductile Iron Pipe Systems forproperexternalprotectionprocedures. Pressure Rating; The working pressure rating ofthe FIELD LOK 350 Gasket Restrained Joint System does not exceed that ofthe working pressure rating of the pipe in which it is installed. u.s. PIPE AND FOUNDRY co. FIELD LOK 350Â® GASKET BRO-080 160502 Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal-Water Sec. 15: Ln 24: Sec. 15: Ln 30: Sec. 15: Ln 33 Vendor: 84890 23U - ANSI/AWWA C153/A21.53 Mechanical Joint Compact Ductile Iron Fittings TY LER U N I ONâ€ Revised022010 Quality Waterworks Products U DOMESTIC D NDN_DOMES."C SUBMITTAL: C153 MECHANICAL JOINT PRODUCT [Current revisions for the noted Standards apply} SIZES: 2â€ through E4â€ I2" not included in ANSIIAWWA C153 standard] STANDARDS: Aivsi/Awwn 0153/421.53, MFPA13224, 3"-10" UL and 3410" FM listed 0. approved (File - Tyler Union} MATERIAL: Cast ofASTM A536 qualified ductile iron. Date code is cast on and required for traceability. PRESSURE RATING: *FIanged fittings rated at 250 psi. Mechanical joints 2" - 24â€ rated at 350 psi and 30â€ -48â€ at 250 psi. *Note: With rubber annular ring flange gasket, 2" â€” 24" Flanged fittings can be rated at 350 psi. Note: Wyes over 12â€ are not pressure rated. Contact Tyler Union for rating in your application. DEFLECTION: lvlaxjoint deflection 2â€œâ€” 12â€œ, 5Â° and l4â€â€” 48â€, 3". Reduces by 50% at nominal pipe 81 fitting diameters NSFâ€”51 81 NSF?-72: Meets all requirements including Annex G, Tyler Union's Underwriters Laboratory listing MH15439. ASPHALT COATING: Per ANSI/AWWA C104/A21.-4 and ANSI/AWWA C153/A2153. CEMENT LINING: Per ANSIIAWWA C10-4jA21.4, with double cement lining. EPOXY COATING: Fusion bonded epoxy per ANSIIAWWA C116/A21.16. Additional coatings available upon request. BARE FITTINGS: Available upon request. FASTENERS: High strength low alloy weathering steel per ANSI/AWWA C111/A2111 and ASTM A242 INSTALLATION: Install per AWWA C600,/C651 using pipe conforming to ANSI/AWWA C151,i'A21.51 orAWWA C9001905. ivâ€”- 0â€”- 1 31 T illel' ' I S r 00.. 2 mm â€œ'\w \ _[T 0.25 K2 ..- 0 0 A 0.12 F KI NOMINALJOINTDIMENSIONS IN INCHES BOLTS Size ADiaâ€˜. BHub C Dia'. W-WI-_n--FDia'. J Dia'. KBâ€˜.3 ia 1 M s T 5â€˜i2e ow. 4 0 50 2 0 3 3 4 5T"-.0230 iouienÂ»- 04 2 tnU5 Uiltoo": 033 324 520230 __ 4_0_0_ _____u'1u1u1â€˜DUI:-I _Â§_____totn ____~03? itoctoa I...I"l--14:001 I-D14?â€˜DUIG0 19149â€˜ r-.11-Di-iilt 000 mu 035 324235 -iDm|â€”\ 030.,1-"1"": 250.Iâ€œ~â€˜!â€˜~'!â€~â€˜ 5'5â€œ00. I"-Jlâ€˜~JC3â€˜ 9991??â€œi-i:::i.o2 200PP.. 050I"-'55â€˜.. 1100 11â€˜lâ€”"ï¬‚-â€˜I10-â€˜J12 003$3... P???$540101 043P.. 03013".E3â€˜. 5-.i-.10ii"e"-0â€˜""' 324235 mmhuw 0.05 2.50 10.12 10.22 0.15 11.25 13.31 13.32 0.00 1.00 0.45 0.30 220 32424.0 10 11.10 2.50 12.22 T234 1120 114500 15.02 15.02 0'50 1.00 0.42 0.40 2/0 3/424.0 12 13.20 2.50 14.32 14.44 13.30 10.25 12.00 12.00 0.23 1.00 0.40 0.42 2/0 3/424.0 mmmm-lb-I=-r~.i 14 15.30 3.50 10.40 10.54 15.44 10.25 20.31 20.25 0.20 1.25 0.55 0.42 2/0 3,/424.5 10 2' 40 50 50 3 54 54 21 00 55 22 0 B 0 55 0 1:| ""-I 3{4x4 Iii"!-"hm Iâ€™-â€˜I-1'52.50 0'1-4U10 I5-._I-I-1~.=='-0250 I'\.Ilâ€”"2:2.I-'4 l-it--1'sari54 I"'1-J5'â€œ.25 I5-I2--I2333 24=00.LNG 11500QUI l"'Iâ€œâ€˜01 0bi.00 2-'4.El-J1 T*2-aeB 3 4x2=-.U'l'L.l'l I-|'l--1'Iâ€˜-JI"-.1 20 21.50 3.50 22.20 22.84 21.74 25.50 22.03 22.00 1.02 1.44 0.59 0.57 2/El 32"4x4.5 14 24 25.50 3.50 25.90 27.04 25.94 30.00 31.53 31.50 1.02 1.55 0.T5 0.51 T,/B 3f4iii5.0 15 30 32.00 4.50 33.29 33.45 32.1? 35.55 39.12 39.12 1.31 2.00 0.82 0.55 1-1,119 1xl':':-.0 20 35 35.30 4.50 39.59 39.75 35.4? 43.25 45.00 45.00 1.45 2.00 1.00 0.74 1-U3 115.0 7-.5 43' 44050 4-50 45.20 2550 43.02 50.02 HE 15352â€˜ 5.45 2.00 T275 0.02 1-3,-'0 '1-122205 20 45 50.50 4.50 52.09 52.25 50.97 52.50 50.00 50.00 1.45 2.00 1.35 0.90 1-3,I'B 1-1!â€™415.5 32 54 Availableon Hequest 50 AvailableonRequest 54 Avallabieon Request Anniston: 1501 W 12"â€œSt. I Ariniston, AL 36201 I [300] 226-2501 Elmer: 201 Kenyon Ave. Elmer, NewJersey 03318 Corona: 1001 El CaminoAve. I Corona, CA92079 I [SEE] 52?-B421 NewLenox: 2200 West Havenl New Lenox, ILE0451 E 11910CR492 I Tyler, Texas T5206 I I800] 52?-B420 Portland: 15570 N. Lombard St. I Portland, DR 92203 Dallas: 1201Ave. 5. 5uite100 I Grande Prairie, TX25050 Oxford: 1800Greenbrier Dear Road IAnniston, AL 3520? Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal-Water Sec. 20: Ln 41: Sec. 20: Ln 44: Sec. 20: Ln 45 Vendor: 84890 _ ZBU - ANSI/AWWA C110/A21.10 E L Class 125 Flange Joint Full Body Ductile Iron Fittings ER U N N O N5â€™ Revised 012010 Quality Waterworks Products |:| DOMESTIC E NON_DDMES.|.|c SUBMITTAL: C110 FLANGE JOINT CLASS 125 PRODUCT lï¬urrerit revisions for the noted Standards a_pply_l SIZES: 2â€ through E4â€ {Contact Tyler Union for 54â€ â€” 64â€ Flange fitting information] STANDARDS: ANSI/AWWA C110/A2110, NFPA 13/â€™24, ASME B101, 3â€ - 12â€ UL listed and FM approved MATERIAL: Cast ofASTM A536 qualified ductile iron. Date code is cast on and required for traceability. PRESSURE RATING: *Flanged fittings *2" â€” 43â€ rated at 250 psi. 5-1iâ€â€” 64â€ rated at 150psi. *Note: With rubber annular ring flange gasket, 2â€ â€” 24â€ Flanged fittings can be rated at 350 psi. DEFLECTION: Deflection is â€œnotâ€ recommended for flange joint due to the rigidity ofthe joint. NSF-61 81 NSF372: Meets all requirements including Annex G, Tyler Union's Underwriters Laboratory listing lvlH16A39. COATING: Asphaltic or Primer per ANSI/AWWA C1042â€™A21.4, Standard primer is Tnemec Pota Pox 140M-1211. Contact Tyler Union for additional coating options. CEMENT LINING: Per ANSI/AWWA E104,i'A21.4, with double cement lining. EPOXY COATING: Fusion bonded epoxy per ANSI/AWWA C116/A2116. Additional coatings available upon request. BARE FITTINGS: Available upon request. FLANGE5: ANSI Class 125 per ASiv1E 015.1 and ANSI/AWâ€˜-NA C111/A2111. Bolt holes shall straddle the center line NOTE: Class 125 ASME B1G.1 are not compatible with Class 250 Flanges NOTE: Class 250 ASME B16.1 fittings are available upon request. FASTENERS: High strength low alloy weathering steel per ANSIIAWWA C111fA21.11 and ASTM A242 INSTALLATION: Install per AWWA CEDDICES1 using pipe conforming to ANSIIAWWA C151,i'A21.51. FLANGE DETAILS IN INCHES BDLTS Inches DI Pipe 0.0. Diameter Thickness "T" Diameter 2 2.51 6.00 4.75 0.62 0.750 5/8 x 2.25 A - 202 2.50 .6-.00 025 0-2:50 2e=<2~2:Â» 0- -I 4.00 0.00 2.50 0.04 0.250 5/000.00 "-0 -i. . . 0.00 11.00 0.50 1.00 0.025 5/4:05.50 I.Â» __ Â£2K,3, o\1 -,| 0.05 10.50 11.25 1.12 0.025 0./4:Â».-0.50 D551-HUI D-'-'-10000-PI y i . '| | 10 11.10 10.00 14.25 1.10 1.000 2/004.00 12 \ 4' ,1-1 .-' 12 15.20 10.01:I 12.00 1.25 1.000 210 x 4.00 12 '4'02â€˜ 12 ____:.->/ _ /7 14 15.00 21.00 10.25 1.0-0 1.125 1 x 4.50 12 '"-(2.2 _ _ _ 16 12.43 23.50 21.25 1.421 1.125 1 x 4.50 16 ~â€”â€”â€”*"â€â€™ 18 19.50 25.00 22.75 1.56 1.250 1-1/'8 x 5.00 10 - 0.0. * 20 21.60 27.50 25.00 1.69 1.250 1-1/3 it 5.00 20 P A W 00 02.00 50.25 00.00 2.12 1.025 1-11405.50 20 <:jâ€™""â€œ ,,... as 00.00 40.00 42.25 2.00 1.025 1-112x2.00 02 -â€”-_______-::â€™}""'--._______ 42 44.50 50.00 40.50 2.02 1.025 1-1/202.50 50 40 50.80 59.50 56.00 2.25 1.625 1-1/2 x 8.0C1 44 54 Available- on Request so Available- on Request E4 Available on Request Anniston: 1503. W 17"â€œ St. Ii Anniston, Al. 36201 I (B00) 225-W501 Elmer: 7'01 Kenyon Ave. Elmer, NewJersey 03313 Corona: 1001 El CaminoAve. 0 Corona, CA 92329 0 [356] 52?-B421 New Lenox: 2200 West Haven: New Lenox, ILE0451 E 11010CR 492 0 Tyler, Texas T5205 I I800] 52?-EMS Portland: 15520 N. Lombard St. 0 Portland, OR 97203 Dallas:1201Ave- S. Suite100 Ii Grande Prairie, TM?5050 Dxforcl: 1800 Greenbrier Dear Road IAnniston, AL3520? Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal -Water Sec. 15: Ln 34: Sec. 15: Ln 37 Vendor: 82790 HD Fowler Company Submittal-Water Sec. 15: Ln 34: Sec. 15: Ln 37 Vendor: 82790 ROMAC INDUSTRIES, INC. ROMAGRIP MECHANICAL JOINT RESTRAINING GLAND 3 THROUGH 12 INCH SUBMITTAL INFORMATION USE The Romac RomaGrip restraining gland is used for the restraint of mechanical joint ductile iron pipe, valves, fittings, and fire hydrants in water transmission and fire protection lines. It may also be used on IPS sizes steel pipe (minimum thickness STD weight class pipe) with MJ by IPS transition gasket. The RomaGrip replaces costly concrete thrust blocks, corrodible steel tie rods and clamps. Not for use on plain end mechanical joint fittings. The RomaGrip may be used on cast iron pipe as long as it has the same OD as ductile iron pipe. Note: Some initial axial movement may occur in lug style restraints as the lugs seat. Movement is directly related to the size of the piping system and the system pressure. In general terms movement of approximately 0.40 may be seen. If this is critical to your application please contact Romac Engineering for additional information. MATERIALS Gland Ductile (nodular) iron, meeting or exceeding ASTM A 536-84, Grade 65-45-12. Gaskets A standard MJ gasket is used with this fitting. Meets ANSI/AWWA C111/A21.11 for gasket specs. Restraining Bolt 7/8 9 roll thread, Ductile (nodular) iron, meeting or exceeding ASTM A 536-84. Restraining Lugs Ductile (nodular) iron, meeting or exceeding ASTM A 536-84. Heat treated using a proprietary process. Lug Locators Polyurethane, a thermo-set plastic. Coatings Shop coat applied to the casting for corrosion protection in transit. Fusion bonded Romabond Polyester coated glands and Xylan coated restraining bolts and lugs optional. PERFORMANCE Nominal Number of Approx. Working Test Maximum Pipe Restraining Weight Pressure Pressure Joint Size Bolts (lbs) (psi) (psi) Deflection 3 2 6 350 700 5Â° 4 2 7.5 350 700 5Â° 6 3 11 350 700 5Â° 8 4 16.5 350 700 5Â° 10 6 23 350 700 5Â° 12 8 29.5 350 700 5Â° FM Approved FM approved for cast iron and ductile iron pipe at 175 psi working pressure (4 : 1 test). UL Listed UL listed for cast iron and ductile iron pipe. Document Number 05-8-0017 8/15 This information is based on the best data available at the date printed above, please check with Romac Engineering Department for any updates or changes. HD Fowler Company Submittal-Water Sec. 30: Ln 79 Vendor: 82790 October 17, 2012 ROMAC INDUSTRIES, INC. 1-800-426-9341 Romac â€œDuctile Lugâ€ www.romac.com Lug: Ductile iron per ASTM A 536, Grade 65-45-12. Use: Restraint of MJ fittings 4" - 24". Accommodates 3/4" rod. Max. Load: 7,500 lbs. 3 5/ Material Specifications 8" 15/ 32" APPROX. WEIGHT CATALOG NUMBER LIST PRICE (lbs.) Ductile Lug .844 # $4.50 Ductile lugs are packaged 50 per box. To Order: Specify catalog number. 90Â° Eye Bolt Eye Bolt: 3/ 4" UNC rolled thread, high strength, low alloy steel per AWWA C111 (Corten or Mayari-R). 1.875" 3/ Nut and Washer: 4" heavy hex, high strength low alloy steel. 90Âº EYE BOLT 2.75" Use: Restraint of MJ fittings 4" - 24". 4.25 3/4" TIE-ROD (see page 7-21) 5.00" Accommodates 3/4" rod. Material Specifications Max. Load: 7,500 lbs. ITEM CATALOG LIST PRICE EACH per QUANTITY APPROX. NUMBER 1 - 200 400 600 800 1000 WEIGHT (lbs.) 3/ 4" Eye-Bolts EYE-3/4 $11.28 $11.20 $11.12 $11.02 $10.88 200 # / crate 3/ 4" Nuts HH-3/4 1.78 1.71 1.66 1.58 1.50 40 # / crate 3/ 4" Washers WASHER-3/4 1.58 1.48 1.48 1.41 1.31 4 # / 100 Bolts and nuts are packaged 200 per crate. To Order: Specify catalog number. 7-20 HD Fowler Company Submittal-Water Sec. 30: Ln 79 Vendor: 82790 ROMAC INDUSTRIES INC. 90Â° EYE BOLT DATA SHEET SUBMITTAL INFORMATION MATERIAL: EYE BOLT 3/4" high strength low alloy steel meets AWWA , 45,000 psi yield strength min. NUT 3/4" heavy hex, high strength low alloy steel meets Mayari- ALLOWABLE FORCE PER BOLT: 7,500 pounds when installed properly. PRECAUTIONS: 1. The number of restraining rods required for a specific application must be carefully engineered. Failure to take into account factors such as pipe diameter(s), peak pressures, deflections, and other key variables can lead to failure of the restraint system. 2. Romac 90Â° eye bolts are not recommended for use on light weight or low quality Mechanical Joint followers. Using these followers for restraint can result in follower failure. 3. Make sure the restraining rod strength is taken into account when calculating the number of rods to use. Not all threaded rod used in pipe restraint is rated for the 7,500 pounds pull that a 90Â° eye bolt can withstand. This information is based on the best data available at the date printed above, please check with Romac Engineering Department for any updates or changes. Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal -Water HD Fowler Company Submittal -Water HD Fowler Company Submittal -Water ROMAC INDUSTRIES INC. STYLE FTS420 TAPPING SLEEVE SUBMITTAL INFORMATION Materials Flange AWWA Class D Steel Ring Flange, compatible with ANSI Class 125 and 150 bolt circles, are standard. Other flange styles are available. Designed to fit tapping valve lip per MSS SP-60 where applicable. Bolts and Nuts High strength low alloy steel bolts and nuts. Steel meets AWWA Standard C111. Type 304 and 316 Stainless Steel bolt material optional. Test Plug Â¾ inch NPT type 304 Stainless Steel. Plug threads coated to prevent galling. Flange Gaskets full face proprietary gasket are made from Styrene Butadiene Rubber (SBR) compounded for water and sewer service in accordance with ASTM D 2000. Other compounds available for petroleum, chemicals, or high temperature service. Outlet Gaskets compounded for water and sewer service in accordance with ASTM D 2000. Other compounds available on request. Coating Fusion bonded epoxy in accordance with AWWA C213. Working Pressure (psig): NOM.PIPE WORKING PRESSURE RATING PER OUTLET SIZE (PSI) SIZE <=3 4 6 8 10 12 14 16 18 20 24 28 30 36 42 48 6 250 250 250 8 250 250 250 250 10 250 250 250 250 175* 12 250 250 250 250 175* 175* 14 250 250 250 250 175* 175* 150 16 250 250 250 250 175* 175* 150 150 18 250 250 250 250 175* 175* 150 150 150 20 250 250 250 250 175* 175* 150 150 150 150 24 250 250 250 250 175* 175* 150 150 150 150 150 28 200 200 200 200 175* 175* 150 150 150 150 150 150 30 150 150 150 150 150 150 150 150 150 150 150 150 150 36 150 150 150 150 150 150 150 150 150 150 150 150 150 150 42 150 150 150 150 150 150 150 150 150 150 150 100 100 100 100 >42 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 NOTE: Meets requirements of AWWA C223 Test Pressure = 1.25 X working pressure. s are provided with a Romac Tapping Flange Gasket. * than 175 psi and up to 250 psi. with class E flanges. For higher pressure ratings consult your representative. SIZES AND RANGES See Catalog. Other sizes available on request. This information is based on the best data available at the date printed above, please check with Romac Engineering Department for any updates or changes. HD Fowler Company Submittal-Water Sec. 25: Ln 53: Sec. 25: Ln 61 Vendor: 77720 SPECIFICATIONS / AVAILABLE CONFIGURATIONS & STYLE NUMBERS (2â€-20â€) M&H AWWA C515 RESILIENT WEDGE GATE VALVES (2000) M&H Valve AWWA C515 Resilient Wedge Gate Valves Meet or Exceed the Requirements of AWWA Standard C515 Size Range Water Working Bubble Tight Hydrostatic Shell Pressure psi Seat Test psi Test psi AWWA 2â€ â€“ 20â€ 250 Water Works 250 & 400 500 ULFM 4â€ â€“ 16â€ 200 Fire Protection 250 & 400 500 Style No. Style No. Style No. Available End Connections (No Gear) Size With With With Range 2â€ Nut Hand wheel Post Plate Mechanical Joint (NRS) (no 2 Â½â€) 2â€-16â€ 7571 7571-HW 7571-P (3â€-16â€) Flanged Ends (NRS) 2â€-16â€ 7561 7561-HW 7561-P (3â€-16â€) Flanged End X Mechanical Joint (NRS) 3â€-16â€ 7572 7572-HW 7572-P (3â€-16â€) Push-on (NRS) (For PVC / SDR) 2â€-12â€ 7597 7597-HW 7597-P (3â€-12â€) Threaded (NRS) 2â€-3â€ 7057 7057-HW 7057-P (3â€only) Threaded (NRS)(With T-Head Nut) 2â€-3â€ 7067-07THN (With T-Head Nut) ***Threaded (OS&Y) 2â€-3â€ N/A 7067 N/A Tyton X Tyton (NRS) (For D.I. / C900) 4â€-12â€&16â€ 7901 7901-HW 7901-P (4â€-12â€&16â€) Tyton X Flange (NRS) (For D.I. / C900) 4â€-12â€ 7902 7902-HW 7902-P (4â€-12â€) ***Flanged Ends (OS&Y) 2â€-16â€ N/A 7068 & 7068A* N/A **Tapping Valve (NRS) 4â€-16â€ 7950 7950-HW 7950-P (4â€-16) M.J. Cutting-in Valve (NRS) 4â€-12â€ 7576 7576-HW 7576-P (4â€-12â€) ****Flanged End (Open Mitre Box) 3â€-12â€ 7211-O 7211-O-HW N/A ****Flanged End (Enclosed Mitre Box) 4â€-12â€ 7211-C 7211-C-HW N/A Style No. Style No. Available End Connections (Bevel Gear) Size With With Range 2â€ Nut Hand wheel Mechanical Joint (NRS) 14-20â€ 7571-B 7571-BHW Flanged Ends (NRS) 14â€-20â€ 7561-B 7561-BHW Flanged End X Mechanical Joint (NRS) 14â€-20â€ 7572-B 7572-BHW Tyton X Tyton (NRS) (For D.I. / C900) 16â€ 7901-B 7901-BHW Flanged Ends (OS&Y) 14â€-20â€ 7068-B 7068-BHW **Tapping Valve (NRS) 14â€-16â€ 7950-B 7950-BHW Style No. Style No. Available End Connections (Spur Gear) Size With With Range 2â€ Nut Hand wheel Mechanical Joint (NRS) 14-20â€ 7571-S 7571-SHW Flanged Ends (NRS) 14â€-20â€ 7561-S 7561-SHW Flanged End X Mechanical Joint (NRS) 14â€-20â€ 7572-S 7572-SHW Tyton X Tyton (NRS) (For D.I. / C900) 16â€ 7901-S 7901-SHW Flanged Ends (OS&Y) 14â€-20â€ 7068-S 7068-SHW **Tapping Valve (NRS) 14â€-16â€ 7950-S 7950-SHW Note: 2â€ to 3â€ sizes full wall ductile iron (per AWWA Dimensions) *7068A is Tapped & Plugged in â€œAâ€ Position (2â€ â€“ 4â€ = Â½â€ tap)(6â€ â€“ 12â€ = Â¾â€ tap) **Each size accommodates a full size diameter tapping cutter.. ***2â€ OS&Y Flanged and Threaded versions are UL Listed ****All other end connections available. 18â€ and larger RS gate valves will be furnished with either bevel or spur gearing. By-pass valve not required on gate valves through 24â€ NOTE: It is recommended that valves be installed with stems vertical when used in raw sewage or sludge applications or in water with excessive sediment. September 1, 2012 / C515 Gate Valves HD Fowler Company Submittal-Water Sec. 25: Ln 53: Sec. 25: Ln 61 Vendor: 77720 RECOMMEND SPECIFICATIONS (NRS STYLE 7000)(OS&Y STYLE 7068)(2â€-20â€) M&H AWWA C515 RESILIENT WEDGE GATE VALVES (2000) RECOMMENDED SPECIFICATIONS (2â€-20â€) 1. Valves shall conform to the latest revision of AWWA Standard C515 covering resilient seated gate valves for water supply service. 2. The valves shall have a ductile iron body, bonnet, and O-ring plate. The wedge shall be totally encapsulated with rubber. 3. The sealing rubber shall be permanently bonded to the wedge per ASTM D-429. 4. Valves shall be supplied with O-ring seals at all pressure retaining joints. No flat gaskets shall be allowed. 5. The valves shall be either non-rising stem or rising stem, opening by turning left or right, and provided with 2â€ square operating nut or a handwheel with the word â€œOpenâ€ and an arrow to indicate the direction to open. 6. Stems shall be cast copper alloy with integral collars in full compliance with AWWA. All stems shall operate with copper alloy stem nuts independent of wedge and of stem (in NRS valves). OS&Y (rising stems) shall be bronze 7. All stems shall have two O-rings located above the thrust collar and one O-ring below. Stem O-rings shall be replaceable with valve fully opened and subjected to full pressure. 8. The stems on 4â€-20â€ shall have a low torque thrust bearing located above and below the stem collar to reduce friction during operation. 9. Waterway shall be smooth, unobstructed and free of all pockets, cavities and depressions in the seat area. Valves 4â€ and larger shall accept a full size tapping cutter. 10. The body, bonnet and O-ring plate shall be fusion-bonded epoxy coated, both interior and exterior on body and bonnet. Epoxy shall be applied in accordance with AWWA C550 and be NSF 61 Certified. 11. Each valve shall have makerâ€™s name, pressure rating, and year in which it was manufactured cast in the body. Country of origin to be clearly cast into body & cover castings. 12. Prior to shipment from the factory, each valve shall be tested by hydrostatic pressure equal to the requirements of AWWA C509 (and UL/FM where applicable). 13. Valves shall have all component parts cast and assembled in the USA and shall be manufactured by the M&H Valve Company. NOTE: It is recommended that valves be installed with stems vertical when used in raw sewage or sludge applications or in water with excessive sediment. September 1, 2012 / C515 Gate Valves HD Fowler Company Submittal-Water Sec. 25: Ln 53: Sec. 25: Ln 61 Vendor: 77720 MATERIAL SPECIFICATIONS (1 of 2) M&H AWWA C515 RESILIENT WEDGE GATE VALVES (2000) CAST IRON SPECIFICATION ASTM A126 CLASS B Physical Properties Minimum tensile strength 31,000 psi Minimum transverse strength 3,300 lbs. Minimum deflection (12â€ Centers) .12 in Chemical Analysis (percent) Phosphorus (maximum) .75 Sulfur (maximum) .15 DUCTILE IRON SPECIFICATION ASTM A536 Physical Properties Minimum tensile strength 65,000 psi Minimum yield strength 45,000 psi SBR-STYRENE BUTADINE RUBBER â€“ ASTM D-5000 â€œO-Ringsâ€ & â€œWedge / Seat Rubberâ€ Hardness 78 5 100% Modulus (PSI) 800 ALTERNATE---EPDM â€œO-Ringsâ€ & â€œWedge / Seat Rubberâ€ Hardness 80 2 100% Modulus (PSI) 600 Tensile (PSI) 1,450 Elongation (%) 150 Compression set, ASTM D395 Method B 18% max. September 1, 2012 / C515 Gate Valves HD Fowler Company Submittal-Water Sec. 25: Ln 53: Sec. 25: Ln 61 Vendor: 77720 MATERIAL SPECIFICATIONS (2 of 2) M&H AWWA C515 RESILIENT WEDGE GATE VALVES (2000) STANDARD CAST BRONZEâ€”ASTM B584 CDA836 (Stem Nut) Physical Properties Minimum tensile strength 30,000psi Minimum yield strength 14,000psi Minimum elongation (in 2 inches) 20% Chemical Analysis *Copper 84.0 â€“ 86.0 Lead 4.0 â€“ 6.0 Tin 4.0 â€“ 6.0 Nickel (maximum) 1.0 Zinc 4.0 â€“ 6.0 * = CU + NI = 79% Min CAST BRONZE â€“ ASTM B584 CDA867 (Stem) Physical Properties Minimum tensile strength 80,000 psi Minimum yield strength 32,000 psi Minimum elongation (in 2 inches) 15% Chemical Analysis Copper 55.0 â€“ 60.0 Lead (maximum) .50 â€“ 1.5 Aluminum 1.0 â€“ 3.0 Iron 1.0 â€“ 3.0 Nickel (maximum) 1.0 Zinc 30.0 â€“ 38.0 Manganese 1.0 â€“ 3.5 Tin (maximum) .2 ALTENATE CAST BRONZE â€“ NDZ-S ASTM B763 UNS C99500 (Stem ) Physical Properties Minimum tensile strength 70,000 psi Minimum yield strength 40,000 psi Minimum elongation (in 2 inches) 12% Chemical Analysis Copper 82.8 Lead (maximum) .25 Aluminum (maximum) 2.0 Iron (maximum) 5.5 Nickel (maximum) 5.5 Zinc (maximum) 2.0 Silicon (maximum) 2.0 September 1, 2012 / C515 Gate Valves HD Fowler Company Submittal-Water Sec. 25: Ln 53: Sec. 25: Ln 61 Vendor: 77720 ITEM DESCRIPTION MATERIAL ASTM SPEC R1 HOLD DOWN HEX BOLT 304 STAINLESS STEEL â€”â€”â€” R2 HOLD DOWN BOLT WASHER 304 STAINLESS STEEL â€”â€”â€” R3 OPERATING NUT OR HAND WHEEL CAST IRON ASTM A126 CLASS B R4 BOLTS/NUTS (STUFFING BOX) 304 STAINLESS STEEL â€”â€”â€” R5 STUFFING BOX/SEAL PLATE DUCTILE IRON ASTM A536 70â€”50â€”O5 R6 Oâ€”RlNG (STEM) QW=3 NBR â€”â€”â€” R7 Oâ€”RING (STUFFING BOX) NBR â€”â€”â€” R8 THRUST WASHER DELRIN â€”â€”â€” R9 STEM (AWWA GRADE C) BRONZE ASTM B584 CDA 867 R1O HEX HEAD BOLTS & NUTS 304 STAINLESS STEEL â€”â€”â€” R11 COVER/BONNET DUCTILE IRON ASTM A536 70â€”50â€”O5 R12 STEM NUT (AWWA GRADE A) BRONZE EPDM ASTM A584 CDA 844 R13 WEDGE/DISC/GATE CAST IRON & SBR COATED ASTM A126 CLASS B R14 Oâ€”R|NG (COVER) NBR â€”â€”â€” R15 BODY â€” ALL TYPES DUCTILE IRON ASTM A536 70â€”50â€”O5 R16 POST PLATE CAST IRON ASTM A126 CLASS B R17 PIPE PLUG (OPTIONAL) GALVANIZED I I: i_ j] â€œÂ§!IÂ§ i_ IJ \ I â€”_ 1 _-.7-I>,///4' Ill !=Â¢/1%; â€” 2- 40 _*Â§ _ _ f Â§Â§EnQâ€˜: E_ 54 L_ ;4 L_ ; \ 44 E_ ; L ;; __ I ,_ -%,,@@, Â§\ Ij I- ,, L_ ~, . â€˜-1.â€˜--_I li-,, \\ /// >â€œÂ§ , > Â§ III_ ~,_ I1_â€˜.yâ€˜I >Â§ > 7 ,, >Â§ ,, LÂ§ â€”< ////////////////////////Â¢ \\\\\\\\\\\\\\ \Â§i I 0 I-I_| sâ€œâ€˜â€œ "â€/// Â§ â€// _ Q) â€™ \~\\â€œ (5) /0 â€//// â€â€™///// | G) G) gg 4â€ 12â€ MACH VALVE COMPANY RESILIENT SEAT GATE VALVE ANN'STÂ°NÂ»"â€˜â€"BAMA Dwg, NO, C515â€”NRSâ€”STYLE 7000 A DIVISION OF MCWANE INC. 7000 VALVE ASSEMBLY / MATERIAL LIST THIS DRAWING AND ALL INFORMATION IS OUR PROPERTY AND SHALL NOT BE USED COPIED. OR REPRODUCED WITHOUT WRITTEN CONSENT. DESIGN AND INVENTION RIGHTS RESERVED. HD Fowler Company Submittal-Water Sec. 25: Ln 53: Sec. 25: Ln 61 Vendor: 77720 LISTED 7572 WITH 2â€ SQUARE NUT @ â‚¬% @E A.W.W.A Standard c515 7572-HW WITH HANDWHEEL WITH POST PLATE Â® 88% APPROVED 7572TID OPTIONAL T K HANDWHEEL 2" SQUARE OPTIONAL POST PLATE Md END IN I=1 ACCORDANCE TO ANSI/AWWA C111/A21.11 E1! G I [E] [E] â€˜ l!l |!| U 11:1] â€˜ Z I â€˜ Q // $ \ I Q D E0 E I 4 * \. / :â€˜Qm â€œâ€˜=iâ€”Q \|i, \\\â€˜ % I K I â€˜CT _T'FT_ NUMBER & 9121: FLANGED END â€˜N <â€”E3â€”> OF sous ACCORDANCE WITH Hâ€”FLANGED ENDS 125 LB. STD. DRILLING Jâ€”MJ END PER ASME/ANSI B161 VQIQIQE A B c 0 E F 6 1-1 J K WEIGHT 2" NUT **3 8 1/4 4 1/4 2 1/2 7 3/4 7 1/2 3/4 12 3/8 4-5/8 4-5/s 1O 38 4 91/4 43/4 21/2 91/8 9 15/16 143/4 s-5/8 4-3/4 10 75 6 101/2 51/4 21/2 113/8 11 1 19 8â€”3/4 6-3/4 12 120 8 12 5/16 6 9/16 21/2 13 3/4 131/2 1 1/8 221/2 8-3/4 6-3/4 14 185 10 141/4 7 3/4 21/2 15 3/4 16 1 3/16 261/2 12-7/6 6-3/4 18 331 12 15 8 2 5/s 18 19 1 1/4 30 12-7/8 8-3/4 18 523 NOTE: 3" MANUFACTURED TO c509 SPEC, BUT MADE OF DUCTILE IRON *HANDWHEEL--ADD 6.5# (3"-4"), 7#(6"), 1o#(s"), 16#(10" & 12") *lND|CATOR POST PLATE ADD 16# <3"-12") ONLY *PALLET QUANTITIES 2" NUT: 3o(3"), 4o(4"), 21(6"), 8(6)", 6(1o"), 4(12") *PALLET QUANTITIES HANDWHEEL: 30(3"), 4o(4"), 21(6"), s(s"), 6(1o"), 4(12") *TURNS TO OPEN: 1o(3"), 13 1/2(4"), 19 1/2(6"), 25 1/2(s"), 31 1/2(1oâ€), 37 3/4(12") **3" to C509 spec but ductile iron DWNI TRIJ 3" 12" I/I&H VALVE COMPANY RESILIENT SEAT GATE VALVE ANNISTON,ALABAMA _ A DIVISION OF MCWANE |1\1c. DWG"7Ng'72 |â‚¬_:|i5AIN5GEST>2ILkI-$7572 THIS DRAWINGANDALLINFORMATION IS OUR PROPERTYAND SHALLNOTBE USED COPIED, OR REPRODUCED WITHOUTWRITTEN CONSENT. DESIGN AND INVENTION RIGHTS RESERVED. Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal-Water Sec. 15: Ln 25 Vendor: 84070 â€˜f_U0â€˜Go!â€˜dmanDrive Â®SEG ERG_ FOR 'câ€˜eaa_mRidge,NJ05514 CORPORATION APPROVAL I I I I W IDRQNO. 1, I Â»~â€”â€”Fs<aâ€™/zz'Â¥@â€”â€”~'-5 Wm I YIva-9224/22230/s2ss1924Â¢2I. M ,. Â»- 1 J_ _.4_â€˜.â€˜ I:Iâ€˜ L..- I I I / \ 1 \ â€˜=A / __ . \_ Â® SIGMA 3, ITEM NO. â€œâ€˜\- HEATNO-.&DATE U3 P# - INDIAR y n|NDIAn â€œ*1/2" RECESSED LETTER I â€˜*1 1/4" E:&:+----I- "I;3_.._____________ I II I II I71/2"r2Jâ€”â‚¬I Ir" " 8"@ Â¿-I , 101/4'15 ___ ,, __ ____ .i _ ____ __ I ; DRG. NO. ~ DIM " A " DIM " B " *WE|GHTW I vs-s224I I 24" A _ 14 1/Ii; 7 3I3_LBSÃ€ . I vaggso _ 7 301; *2o1r2" ??LBS ?_ I vs-9236 as" W 2e 1/2" 751 LBS f I vs;9IÃ©_4I2i 42" 3211;" I ??LBSH_'__ _ W I : I DESCRIPTION: A I Iâ€™\IIATERIT\II;:IIGfafCast Iron I -I I ( I ~ ( RICH VALVE BOX BOTTOM cammm PAINTED , . I I_â€˜cI1;1Ec|<E5Ã©Y: I I mac-:.waI1bcIÃ©Â§TIf IÂ»Â§PI5\/DIONâ€˜: R5/I|Ã©|o|\i-*0" IlÂ§1;IDf_-Â§II3III\I}Â°l"[Hl.* " j AÂ§HIS_DIÂ§Y. 7 Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal-Water Sec. 15: Ln 26 Vendor: 84175 1|76:9â€œ[|iWja__l__ GOId F > @ 1â€˜â€˜JS08 __â€œOHD} $202>|> 1|[JS@_@@___ Say; SN?â€œ _____A__ L |_|_|_ :8 1WOI_E1_J_wUâ€˜mg_ZUC3_gm\m_wÂ§_<__5_ï¬‚_w<<:_IOC___â‚¬E_____,_wZ_m___Im_"__w_Â§_mm_OZ_ï¬‚_mENoUCO]:OzOm_Zm_1_zUCm1_JEmm\m_mW>Z___OEU__>72___>W]_lOWOF?/SZO>m_m:5>HIM]_lI_m_Z_HO_HC<_>]_]_OZ<<IO_L_mMOEOOZ]_l>_Z_mU_v_~o_u_h_m;_ï¬‚<_u__ï¬‚O_____wWâ€˜_)<_ZOm>20noz_â€œ_U_m_â€™___>_ 500 _| h OD:>Ummg_3_O_/_<UzmmE wO>_|_wU0mm<_m_OZZ9_mgrmHmU_~><<__/_O _MWN 1_Z_mT_gmU29Ooggmzau_/_O_ gm/1%Â§g_>r-gmmo__w8%umH\W/AU_N>3_ZN>_U_U_OX_>__ï¬‚_QmwuO83MO":Wï¬‚wmgmï¬ormwwwoo3Â°:>50â€œâ€œEm>_U_Â§_E:gw_Â§___Â§___%\%_s______â€˜______\_ 92__Â°__U_N>2_/__12_ >m;>>2â€œ 0__Â§Â§___6_Om\Oo\;3%_8|Â§|@_wow__â€œTQXHq_w$ww|2K >ZOrmm%_Mg\]_/my ___O_|_%>7_O_w_ U_7>_mZm_OZm<>__<mÂ£5â€œ>mmE/__|_m$____o_u__Z__m__woxO____|__m_N<<G_m_ZQ__mm%_mn_1__mU_ OU15___ go 2|__m_m_O_H_ _N_m< Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal-Water Sec. 15: Ln 27 Vendor: 84175 mUh_ 1||_____Sam 69$_LwiwSmogI @_$__m_gL1% I.% L_b___mLI J3_Pll /_â€™__ J___| Â§H__%_H__DOmg__mZ2_UÂ§Â£_zmmm{__w__UzEn_EÂ§_~_ï¬Hï¬E__m__ï¬‚__bÂ§ï¬__Â§_M_Hï¬___FPE300%UmÂ§_3_Oz_Z:__________)__â€œE___:____â€œ______ï¬‚_*__â€™____=m_~___r___=__gmUm5___:__â€œ_________Â£___ï¬_________d__â€œ.__J_____â€˜:____U_J_â€œ_%__T____H_____I_â€œNm________z_U_2;______H_z_mI_Â£_:1________â€™____:____m%_:_w=_____Â£mm:_n_"U___________L_m____GH____E______m_____=_3__â€œ_n__m________â€™__an________u 7|__m_n__ QI_|_m_______m_~____ _I |_| mmgoz}|__P NR5 â€˜_U_m}{____z_____m_____'____Fmz}__S_ï¬‚â€˜Ira_â€™___}n___@______tâ€œ_____â€™__Dam_}__|___H_|_r_m___H_______1ï¬xDm}q1_}ï¬m__rm:_uâ€œ__=____â€œ_H__1___E1__}g__uK_U_UÂ¢:Em_u_n g___U5H__E"_H__E________H___=Q_=hH_2_m_â€œ\_%mï¬a=H%Q:__\m:_;_u_D_{__Â£HEm E|Â§'&_E%__"___"_EH____i___;D__32%m__Â§__hmD%__E|Â§T_m__j~Â¥Ill.â€˜I _|L w__mm_ï¬__H_"uD__Um_EngMac:_U___{__w 5:mm_â€™%__nmuUmmuUE_mZm__U_EwM__ï¬_â€____p__m_mEaâ€œ:â€œOFgram_Z____________<_mUHIm_Â§_mm_Zï¬Imm____u_M_u_mn_1_5"103EEO _M H}_|mQ__Ewig "H? Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal-Water Sec. 30: Ln 74 Vendor: 77720 GENERAL FEATURES / SPEC M&H AWWA C502 FIRE HYDRANTS Style 929 Traffic Model 250 PSI Working Pressure â€“ 500 PSI Hydrostatic Test â€“ AWWA UL / FM Approval Type: Compression type, opening against line pressure. working parts, including main valve assembly, are Main valve on Traffic Model will remain closed should removable through the top of hydrant without excavating. hydrant be broken off by traffic accident. Two positive acting non-corrodible drain valves are integral parts of main valve assembly. All parts of hydrant of same Classification and Size: Hydrants are classified by the size and type are interchangeable with out any special main valve size, number and size of hose and pumper fittings. Integral operating nut and weather shield provide nozzles. Hydrant size is designated as a 5 Â¼ â€œ, size being tamper resistant top works and protects the operating the inside diameter of the main valve seat opening. mechanism form the elements. Also operating hold down is O-ring sealed for added protection. Length: Hydrant lengths are determined by depth of trench below ground level. Lengths are in multiples of six inches. Dry Top: Operating threads are isolated from the waterway by a seal plate having double O-rings. Operating nut has Barrel: Upper section of barrel (nozzle section) contains the lubricating hole in top for lubrication of operating threads hose and pumper nozzles. The water way is uniform in and thrust bearing. diameter for entire length of barrel. Dry Barrel: When the valve of the hydrant is closed, two Hydrant Inlet: Hydrant shoe or elbow is provided with drain valves in the hydrant shoe automatically open and flange or mechanical joint connection to fit connecting pipe. allow rapid and complete drainage of the hydrant barrel. All type shoes except flanged are provided with lugs for This dry barrel eliminates danger of damage to the hydrant strapping. The two drain openings in the hydrant shoe are by freezing. bronze bushed. All shoes are protected from corrosion with fusion bonded epoxy coating. Materials of Construction: All iron parts are made of high strength gray iron conforming to specification A-126, Class Hose and Pumper Nozzles: Threaded and screwed into B of the American Society for Testing Materials or ductile tapped openings in nozzle section of hydrant. Hose and iron. All non-corrodible metal parts are made of copper pumper nozzle caps are provided with rubber gaskets and alloys conforming to AWWA Standard C502 requirements. chained to nozzle section. Other materials are also of high quality for their respective uses. Operating Mechanism and Working Parts: Main valve rod is made of steel and is bronze sheathed where it passes Shop Tests: Tested to 500 pounds hydrostatic pressure through a two piece bonnet system. Bronze retainer ring supplied from the inlet side, first with main valve closed for bushing is permanently affixed into shoe. Main valve seat testing of valve seat; second, with main valve open for ring is threaded into seat retainer ring providing bronze to testing of drain valves and entire hydrant. bronze assembly. Main valve seat material is rubber. All September 2012 / M&H C502 / Model 929 HD Fowler Company Submittal-Water Sec. 30: Ln 74 Vendor: 77720 SUGGESTED SPECIFICATIONS (1 of 2) M&H AWWA C502 FIRE HYDRANTS Model 929 Traffic Model 250 PSI Working Pressure â€“ 500 PSI Hydrostatic Test - AWWA UL / FM Approved _______________________________________________________________________________________ GENERAL Fire hydrants shall comply in all respects with AWWA Standard C-502, latest revision. Fire hydrants shall be of the compression type, with the main valve opening against the pressure and closing with the pressure. The main valve opening shall be (5 Â¼â€) in diameter. Fire Hydrant shall be of a dry barrel, dry top design. The nozzle section shall consist of two (2) hose nozzles and one (1) pumper nozzle or other as specified. _______________________________________________________________________________________ RATING Fire hydrants shall be rated at 250 psi water working pressure, tested at 500 pounds hydrostatic for structural soundness in the following manner: 500 pound hydrostatic test supplied from the inlet side, first with the main valve closed for the testing of the valve seat: second, with the main valve open for testing of the drain valves and the hydrant barrel. Testing to be complete in accordance with AWWA C-502 and UL & FM requirements. _______________________________________________________________________________________ END Hydrants shall be connected to the main by a 6â€ fusion bonded, epoxy coated mechanical joint or CONFIGURATION flanged shoe. Mechanical joint shoes shall be fitted with strapping lugs. _______________________________________________________________________________________ DESIGN The main valve seat of the hydrant shall be made of rubber and be supported by a one-piece bronze top plate / drain valve mechanism. Drain valves shall have replaceable rubber facings. The bottom stem threads of the main valve rod shall be fitted with an epoxy coated, cast iron bottom plate, sealing lower rod threads from the water. Changes in size or shape of the waterway (hydrant nozzles) shall be accomplished by means of easy curves. Exclusive of the main valve opening, the net area of the waterway of the barrel and the foot piece at the smallest part shall not be less than 120% of that of the net opening of the main valve. Hose and pumper nozzles shall be threaded and screwed into the nozzle section. And then mechanically locked to prevent turning. Hose and pumper caps shall be chained to the hydrant The hydrant shall be so designed that when it is in place, no excavation will be required to remove the main valve and movable parts of the drain valve. Further, the hydrant shall be of the type that can be extended without excavating. Hydrants shall be so designed that, in the event of accident, or breaking of the hydrant above or near grade level; the main valve will remain closed. The main valve rod shall be made in two parts and fitted with breakable coupling at the ground line flange. The ground line connection between nozzle section and the barrel shall incorporate the use of breakaway lugs. This connection shall be so designed that the nozzle section can be rotated in any increment of 360. The ground line connection between the barrel and nozzle sections shall have an o-ring to provide a seal. The operating threads of the hydrant shall be so designed as to avoid the working of any iron or steel parts against either iron or steel. The operating stem and operating nut threads shall be square or acme type. September 2012 / M&H C502 / Model 929 HD Fowler Company Submittal-Water Sec. 30: Ln 74 Vendor: 77720 SUGGESTED SPECIFICATIONS (2 of 2) . DESIGN The operating thread shall be lubricated at factory with food grade grease. Access shall be provided (Continued) to field lubricate the operating mechanism. The operating thread shall be sealed from water at all times when the valve is either in the opened or closed position. The operating rod shall be bronze sheathed where it passes through the double â€œOâ€ ring seal in the bonnet. The bonnet shall be weather proof and utilize a weather shield integral with the external wrench operating nut. The operating nut shall be made of bronze with a self-lubricating design. Hydrants shall be of the dry barrel type and hydrant shoe shall have two positive acting non-corrosive drain valves that shall drain the hydrant completely by opening when the main valve is closed, and close tightly in accordance with AWWA C-502 requirements when main valve is open. The main valve assembly shall be seated in the hydrant with a bronze-to-bronze interface to facilitate removal of the main valve, should maintenance be required. The nozzle section shall consist of two-2 1/2â€ hose nozzles to the specified thread designation (NST or other, as specified) and one pumper nozzle 4 Â½â€ in diameter to the specified thread designation (NST or other, as specified), or other combination of nozzle outlets, including independent hose gate valves, as specified. Two O-ring seals shall be utilized where the main hydrant rod passes through the 1 piece bonnet. Hydrant standpipe shall be ductile iron and single piece for all bury depths. All like parts of hydrants of the same size and model produced by the same manufacturer shall be inter- changeable. Hydrant shall open by turning to the (left or right). Direction of opening to be permanently marked on hydrant bonnet. Threads on hose and steamer nozzles shall be National Standard unless otherwise specified. Size and shape of operating nuts cap nuts shall conform to National Standard unless otherwise specified. Bury shall be (specify depth of bury) measuring depth from grade line to bottom of trench or connecting pipe. Auxiliary shut-off (isolation) gate valves, when required, shall be of the same manufacture as the hydrant. _______________________________________________________________________________________ COATING Hydrant shoes shall have an interior and exterior thermosetting epoxy coating of 5 to 6 mils meeting AWWA C550. Exterior on hydrant nozzle section shall be Fire Hydrant Red (or as specified). _______________________________________________________________________________________ MARKINGS Hydrant shall be marked with the name of the manufacturer, size of valve opening, direction of opening and the year of manufacture all in accordance with the AWWA C-502. Country of origin to be cast on all major hydrant castings. _______________________________________________________________________________________ SOURCE Hydrants shall be M&H Model 929 or approved equal September 2012 / M&H C502 / Model 929 HD Fowler Company Submittal-Water Sec. 30: Ln 74 Vendor: 77720 Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal-Water Sec. 30: Ln 76 Vendor: 72810 HD Fowler Company Submittal -Water Sec. 30: Ln 76 Vendor: 72810 Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal -Water Beauwest Fasteners HD Fowler Company Submittal-Water Sec. 30: Ln 77 Vendor: 77780 HD Fowler Company Submittal-Water Sec. 30: Ln 77 Vendor: 77780 Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal-Water Sec. 30: Ln 83 Vendor: 70840 %|TE HYDRANT GUARD POST I N C O H P D R A T E D Qâ€œ:- MÂ£z?1â€˜Â£2I;. Robs â€œâ€œâ€˜â€œ""""" 6 I I \__/ n-5'â€”Â¢ |I|4mâ‚¬Tâ€˜El'L 285* page 51 Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) HD Fowler Company Submittal-Water Sec. 20: Ln 52 Vendor: 67890 â€” PRODUCT INFORMATION & SPECIFICATIONS â€” Detectable Marking Tape Christyâ€™sâ„¢ Detectable Marking Tape provides for easy buried pipeline detection and below ground identification and warning. The tape can be located below ground with a non-ferrous metal detector, when buried at the proper depths. Christyâ€™sâ„¢ Detectable Tape Must Be Buried Flat For Maximum Detectability and Line Protection. We recommend bury depths of: TAPE WIDTH 2â€ 3â€ 6â€ 12â€ or wider TAPE BURY DEPTH 6â€ - 18â€ 6â€ - 28â€ 6â€ - 36â€ 6â€ - 36â€ Detectable Marking Tape SPECIFICATIONS Tape consists of Minimum 4.5 MIL overall thickness, with 0.0035 MIL solid aluminium foil core. The warning mes- sage is â€œBuried, or Encasedâ€ to prevent ink rub-off and is impervious to acid, alkalis and other destructive elements found in soil. All Christyâ€™s tape meets or exceeds the industry standards including the America Public Works As- sociation (APWA) color code. TEST DATA VALUE MATERIAL IDENTIFICATION 3â€ & 6â€ WIDE 4.5 MIL OVERALL FOIL THICKNESS 0035 MIL TEST PROCEDURE ASTM-D-8820, METHOD A 90% SPECIMEN CONDITIONS 73ÂºF / 50% R.H TEST TEMPERATURE 73ÂºF ELONGATION 90% TENSILE STRENGTH TRANSVERSE 5530 PSI TENSILE STRENGTH LONGITUDINAL 4544 PSI ROLL WEIGHT 3â€ X 1000â€™ +â„- 7.5 LBS ROLL WEIGHT 6â€ X 1000â€™ +â„- 15 LBS MINIMUM WEIGHT 10 LBS PER 1000â€™ UNIT MAXIMUM IMPRINT LENGTH 36â€ COLOR CODE DESCRIPTION Blue WATER & ASSOCIATED LINES BROWN FORCE MAINS & ASSOCIATED LINES GREEN SANITARY & ASSOCIATED LINES ORANGE TELECOMMUNICATIONS & TELEPHONE LINES purple RECLAIMED WATER LINES reD ELECTRIC & ASSOCIATED LINES YELLOW GAS & ASSOCIATED LINES The tape is manufactured by T. Christy Enterprises, Inc. (800) 258-4583. The model number is _________________ (TA-DT-XX-XXX). See model number designations on the following page. Subject to change without notice. May 2011 www.tchristy.com â€¢ (800) 258-4583 HD Fowler Company Submittal-Water Sec. 20: Ln 52 Vendor: 67890 â€” PRODUCT INFORMATION & SPECIFICATIONS â€” STANDARD COLOR/LEGEND COMBINATIONS How to Order Underground Marking Tapes TA.XX.XX.XXXXX example: TA.DT.2.PRW is 2" Detectable Purple Reclaimed Water. Type of Tape Width of Tape Colors Legend DT - Detectable 2 - 2" B - Blue Cp - Cathodic protection RAW - Raw Water 3 - 3" p - purple e - electric rJ - restrained Joint 6 - 6" Y - Yellow F- Fire RW - Reclaimed Water 12 - 12" G - Green FM - Force main STDR - Storm Drain r - red FO - Fiber Optic T - Telephone W - White G - Gas W - Water O - Orange I - Irrigation Br - Brown NPW - Non-Potable Water STANDARD COLOR/LEGEND COMBINATIONS Color Legend Text Blue BI "Caution Irrigation Line Buried Below" Blue BNPW "Caution Non-Potable Water Line Buried Below" Blue BPW "Caution Potable Water Line Buried Below" Blue BW "Caution Water Line Buried Below" Blue rJ "Caution restrained Joint Buried Below" Brown BFM "Caution Force Main Buried Below" Green GFM "Caution Force Main Buried Below" Green GI "Caution Irrigation Line Buried Below" Green GNPW "Caution Non-Potable Line Buried Below" Green GPW "Caution potable line Buried Below" Green GRAW "Caution Raw Water Line Buried Below" Green GS "Caution Sewer Line Buried Below " Green GSTDR "Caution Storm Drain Buried Below" Orange OFO "Caution Fiber Optic Line Buried Below" Orange OT "Caution Telephone line Buried Below" Orange OCP "Caution Cathodic protection Cable Buried Below" purple PRW "Caution Recycled/Reclaimed Water Line Buried Below" purple PNPW "Caution Non-Potable Line Buried Below" red re "Caution electric line Buried Below" NOTE: Not all widths are red rF "Caution Fire line Buried Below" available as standard for Yellow YG "Caution Gas Line Buried Below" the stock color/legend combinations shown. Contact Christy'sâ„¢ SPECIAL AND CUSTOM LEGENDS for stock availability of Christy'sâ„¢ offers a full range of non-standard legend/color combinations in addition to the specific products. Non- combinations listed below, including specialty applications such as Telemetry, Irrigation stock combinations are and additional water line wording. All standard combinations listed are available in at subject to minimum least one color/width combination. We offer specific agency legends, designations or requirements and plate color combinations. Custom legends can include the use of specific wording, insignias charges. and phone numbers. Call for special pricing. Subject to change without notice. May 2011 www.tchristy.com â€¢ (800) 258-4583 Powered by TCPDF (www.tcpdf.org) Powered by TCPDF (www.tcpdf.org) Table of Contents 1.0 Project Overview ....................................................................................................................1 2.0 Existing Conditions Summary ...............................................................................................3 3.0 Off-Site Improvements ...........................................................................................................4 4.0 Off-site Analysis Report .........................................................................................................6 5.0 Minimum Requirements ........................................................................................................7 Governing Guidelines ...............................................................................................................9 Design Criteria ..........................................................................................................................9 6.0 Stormwater Control Plan .....................................................................................................16 Existing Site Hydrology .........................................................................................................16 Developed Site Hydrology .....................................................................................................16 Performance Standards and Goals ..........................................................................................17 7.0 Stormwater Pollution Prevention Plan (SWPPP) ..............................................................18 8.0 Special Reports and Studies .................................................................................................19 9.0 Other Permits ........................................................................................................................20 Table of Figures Figure 1 â€“ Vicinity Map .................................................................................................................2 Figure 2 â€“ Off-site Drive Aisle Aerial (2009) ...............................................................................5 Figure 3 - Flow Chart for Determining Requirements for New Development ........................8 List of Appendices Appendix A â€“ Improvement Plans Appendix B â€“ Flow Control Appendix C â€“ Runoff Treatment Appendix D â€“ Well Head Protection Zones Appendix E â€“ Soil Map Appendix F â€“ Operations and Maintenance Manual Stormwater Site Plan Page i Arlington Electrical Equipment &Pole Storage Yard July, 2016 1.0 Project Overview This Stormwater Site Plan Report provides stormwater requirements and design calculations for the proposed Snohomish County PUD No. 1 Arlington Electrical Equipment and Pole Storage Yard. The project property is located on 59th Ave NE south of the intersection with 180th Street NE, Arlington, WA 98223 within a portion of Section 22, Township 31, Range 5 East, WM. The project site is approximately 26.5 acres in area. Industrial uses border the site in all directions. 59th Ave NE borders the west side of the parcel, and railroad tracks owned by BNSF border the parcel to the east. A temporary storage yard adjacent to 59th Ave NE was constructed in 2013 creating 0.23 acres of gravel surfacing. There is no other impervious surfacing on-site. The site is predominately flat with slopes on average approximately 1-3 percent. The northeast corner of the site is approximately 10 feet higher than the western portion of the parcel. There are no known existing surface flows leaving the site. All stormwater runoff infiltrates onsite into existing outwash soils. Only a portion of the site will be developed. The 1.7 acre yard is centrally on the larger site. Access to the proposed yard will be via an access and utility easement on the AAMP (northern property owner) property. The access easement will provide a paved surface (with a minimum width of 20 feet) north to 180th Street NE and then west onto 59th Ave NE. The total disturbed area is approximately 5.0 acres. The developed storage yard is 1.7 acres in size finished with permeable gravel and asphalt. The remaining disturbed area will be used for on-site disposal of organic strippings. A water main will also be extended from the Pick and Pull site to the south connecting into the AAMP facility to the north. The proposed stormwater facilities will comply with the 2012 Department of Ecology Stormwater Management Manual for Western Washington (DOE Manual) and the City of Arlington Design and Construction Standards and Specifications. The pollution generating impervious surfaces (PGIS) will be treated by a water quality layer of material within the gravel surfacing prior to infiltrating into the existing subgrade. Refer to Section 4 of this report for additional information on the proposed drainage systems. Stormwater Site Plan Page 1 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Figure 1 â€“ Vicinity Map Project Site Stormwater Site Plan Page 2 Arlington Electrical Equipment &Pole Storage Yard July, 2016 2.0 Existing Conditions Summary The project site is approximately 26.5 acres in area. The project consists of one parcel. There is a small building, approximately 2,000 square feet centrally located on the parcel. The building, a dilapidated barn, is the only structure onsite. The rest of the parcel is vegetated predominately with grass and shrubs. There are a few trees scattered throughout the site. To the north of the site are multiple larger buildings (warehouses), and to the south of the site is a parking lot and miscellaneous buildings. The site is predominately flat with slopes on average approximately 1-3 percent. The northeast corner of the site is approximately 10 feet higher than the western portion of the parcel. There are no known existing flows leaving the site. All stormwater runoff infiltrates onsite into the existing soils. According to the Natural Resources Conservation Service (NRCS), the soils on the project site primarily consist of Lynnwood loamy sands with 0-3 % slopes with a Hydrologic Soil Group Type A. A Type A soil was used in WWHM3 for stormwater facility sizing purposes. GeoEngineers completed a geotechnical engineering report establishing a minimum of 1.2 inches/hour as the estimated long-term infiltration which was used in facility sizing. A portion of the site lies within a wellhead protection zone. A City of Arlington airport well is located approximately 2,000 feet north of the project site. The eastern half of the site which is where the proposed development is located is within the 1-year and 1-year buffer protection zones. See Appendix D for wellhead protection zone map. Stormwater Site Plan Page 3 Arlington Electrical Equipment &Pole Storage Yard July, 2016 3.0 Off-Site Improvements In order to establish paved access for emergency vehicles a 20â€™ wide drive aisle will be paved with asphalt treated base. The proposed improvements are temporary until AAMP (property owner to the north) and/or the City of Arlington construct full roadway improvements as described in â€œAgreement for Deferral of Inprovementsâ€ recording number 201112200120. The area to be paved was historically a parking lot for Bayliner employees (see Figure 2). Since the AAMP property was redeveloped (about 2011) the parking area has largely been unused. The conversion of this area to a paved surface will not impact the larger infiltration storm system that was designed to handle drainage from the gravel parking area with similar runoff characteristics. The temporary asphalt drive aisle will be replaced with construction of full roadway improvements and new stormwater facilities. Stormwater Site Plan Page 4 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Figure 2 â€“ Off-site Drive Aisle Aerial (2009) Stormwater Site Plan Page 5 Arlington Electrical Equipment &Pole Storage Yard July, 2016 4.0 Off-site Analysis Report This section evaluates the upstream and downstream drainage system. The intent of this section is to identify any existing or potential drainage impacts created or exacerbated by the proposed project and drainage facilities. Task 1: Study Area Definition The offsite analysis study area was conducted with the use of Snohomish County GIS aerial and topographic information and a topographic survey of the site. Task 2: Review of available information The following resources were utilized in preparation of this section: USGS Topographic Map Snohomish County PDS Permit, Planning and Zoning Interactive Map City of Arlington Wellhead protection Zone Map National Resources Conservation Service Web Soil Survey Task 3: Upstream & Downstream Study An upstream and downstream study was not completed because there is no upstream drainage basin and all stormwater infiltrates into the existing site soils. Stormwater Site Plan Page 6 Arlington Electrical Equipment &Pole Storage Yard July, 2016 5.0 Minimum Requirements Not all of the Minimum Requirements apply to every development or redevelopment project. The applicability varies depending on the type and size of the project. This section identifies thresholds that determine the applicability of the Minimum Requirements to different projects. The flow chart below identifies the applicable requirements. Stormwater Site Plan Page 7 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Figure 3 - Flow Chart for Determining Requirements for New Development Start Here Does the site have Yes See Redevelopment 35% or more of Minimum existing impervious Requirements and coverage? Flow Chart (Figure 2.3) No Does the project convert Â¾ acres of native vegetation to Does the project add No lawn or landscaped 5,000 square feet or areas, or convert 2.5 more of new acres of native impervious surfaces? vegetation to pasture? Yes No Yes Does the project have 2,000 square feet or All Minimum more of new, replaced, Requirements apply to or new plus replaced the new impervious impervious surfaces? surfaces and converted pervious surfaces. Yes No Minimum Does the project have Requirements #1 land-disturbing through #5 apply to activities of 7,000 the new and replaced Yes square feet or more? impervious surfaces and the land disturbed. No See Minimum Requirement #2, Construction Stormwater Pollution Prevention Stormwater Site Plan Page 8 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Governing Guidelines The project site is located within the City of Arlington. The Washington State Department of Ecology Stormwater Management Manual for Western Washington, 2012 (DOE Manual) will be used for stormwater design. The Western Washington Hydrology Model Version 2012 (WWHM), a continuous simulation model will be used to size all stormwater facilities. Design Criteria Per Figure 8 in the DOE Manual â€“ Flow chart for determining requirements for new development â€“ all minimum requirements apply to the area of the site being developed. The following section describes how each Minimum Requirement (MR) will be incorporated into the proposed project. MR #1 through #10 are addressed as follows: MR #1: Preparation of Stormwater Site Plans. This report and accompanying improvement plans constitute the Stormwater Site Plan. MR #2: Construction Stormwater Pollution Prevention (SWPPP). A SWPPP will be prepared as a separate document for use during construction. Even though the project likely does not require coverage by a Department of Ecolgoy Construction Stormwater General Permit due to on-site infiltration the District will obtain coverage in the unlikely event construction stormwater leaves the project site. The following section provides a detailed description of the BMPs to be implemented based on the 12 required elements of the SWPPP. For additional information refer to the project TESC plans and SWPPP. Element #1 â€“ 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. A large portion of the site will remain undisturbed throughout construction. Clearing limits will be delineated by silt fence and high visibility fence. The following relevant BMPs for this project include: BMP C101: Preserving Natural Vegetation BMP C233: Silt Fence BMP C103: High Visibility Plastic or Metal Fence Element #2 â€“ Establish Construction Access Stormwater Site Plan Page 9 Arlington Electrical Equipment &Pole Storage Yard July, 2016 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. The following relevant BMPs for this project include: BMP C105: Stabilized Construction Entrance BMP C107: Construction Road/Parking Area Stabilization Element #3 â€“ Control Flow Rates In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site will be controlled. The following relevant BMPs for this project include: Not applicable. It is anticipated that all construction stormwater will infiltrate into the existing subgrade. Element #4 â€“ Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before entering a receiving water body. The following relevant BMPs for this project include: BMP C220: Storm Drain Inlet Protection BMP C233: Silt Fence Element #5 â€“ 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 following relevant BMPs for this project include: BMP C120: Temporary and Permanent Seeding BMP C121: Mulching BMP C123: Plastic Covering 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. Element #6 â€“ Protect Slopes All cut and fill slopes shall be designed, constructed, and protected in a manner that minimizes erosion. The following relevant BMPs for this project include: Stormwater Site Plan Page 10 Arlington Electrical Equipment &Pole Storage Yard July, 2016 BMP C121: Mulching Element #7 â€“ Protect Permanent Drain Inlets All existing and proposed storm drain inlets and culverts made operable during construction that may receive stormwater on and downstream of the site shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. The following relevant BMPs for this project include: BMP C220: Storm Drain Inlet Protection Element #8 â€“ Stabilize Channels and Outlets There are no known channels and/or outlets on site to stabilize. Element #9 â€“ Control Pollutants All pollutants, including waste materials and demolition debris, that occur during construction 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. Vehicles, construction equipment, and/or petroleum product storage/dispensing: â€¢ 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. â€¢ Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. â€¢ Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. 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 C151). In order to prevent, reduce, or eliminate the discharge of pollutants from material delivery and storage to the stormwater system, Material Delivery and Storage Contamination (BMP C153) shall be implemented. Stormwater Site Plan Page 11 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Sanitary wastewater: Portable sanitation facilities will be firmly secured, regularly maintained, and emptied when necessary. Solid Waste: Solid waste will be stored in secure, clearly marked containers. Element #10 â€“ Control Dewatering Large scale dewatering is not anticipated during construction. A sedimentation bag with outfall into existing vegetation will be used for small volumes of localized de-watering. Element #11 â€“ 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 BMPâ€™s 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. Element #12 â€“ Manage the Project All BMPâ€™s shall be inspected and repaired in accordance with DOE permit requirements. The full project SWPPP will be kept on-site during construction. Element #13 â€“ Protect Low Impact Development BMPâ€™s The project does not have traditional low impact development BMPâ€™s. The project will utilize a custom biorention soil mix under a pervious gravel section for stormwater treatment. A geotechnical special inspection will be on-site during construction to verify the Contractor follows proper construction to no foul or over compact the pervious section material and/or subgrade. The District will also be providing periodic inspection to verify the TESC and SWPPP measures are properly installed and maintained throughout construction. MR #3: Source Control of Pollution. All known, available and reasonable Source Control BMPs shall be applied to this project. The District will promptly contain and clean up solid and liquid pollutant leaks and spills including oils and fuels. The District will periodically contract street sweeping to remove dust and debris that could contaminate stormwater and will not hose down Stormwater Site Plan Page 12 Arlington Electrical Equipment &Pole Storage Yard July, 2016 pollutants. The District will maintain the transformer storage area including periodic inspection of the oil stop valve and will repair the pavement and containment area if damaged. Any damaged and/or leaking equipment will promptly be removed from the site and repaired at the Districtâ€™s Operations Center. MR #4: Preservation of Natural Drainage Systems and Outfalls. The proposed stormwater site plan will maintain the existing outfall infiltrating into the existing subgrade. MR #5: On-Site Stormwater Management. The DOE Manual requires the use of on-site Stormwater Management BMPs to infiltrate, disperse, and retain stormwater runoff on-site to the maximum extent feasible without causing flooding or erosion impacts. Existing onsite soils and the proposed stormwater facility design allows for 100% infiltration of all proposed impervious and pervious surfaces from 50% of the 2 year peak flow up to the full 50 year peak flow as modeled by WWHM2012. MR #6: Runoff Treatment. The developed portion of the site will be used for industrial uses which requires enhanced water quality treatment per the DOE Manual. Treatment of stormwater runoff will be provided by a custom bioretention soil mix within the pervious (or gravel) areas. The custom bioretention soil mix complies with the Volume V, page 7-17 of the DOE Manual. A custom soil mix will be used due to a couple factors. The existing topsoil does have a cation exchange rate greater than five, however the depth of the topsoil is less than 18 inches which is insufficient for water quality treatment. The site will also be developed in the winter months which is not ideal for mixing and reuse of existing on-site materials. The paved access drives will be designed to sheet flow drainage into the pervious gravel sections for treatment prior to infiltration. The gravel areas have been designed to treat the tributary pavement areas. In order to allow for treatment within the 18â€ water quality section without backwatering during large storm events a 4â€ layer of rock was also incorporated into the gravel section to allow for ponding at the subgrade interface prior to infiltrating into the subgrade. The site design also incorporates a paved and curbed area for transformer storage. The transformers stored on-site are filled with a non-conductive mineral oil. Mineral oil transfer and/or filling will not occur on-site so the spill potential on-site is limited, however vandalism has resulted in oil spills of stored and/or operational transformer in the past. To reduce the risk of contaminating soil as a result of an accidental spill an oil stop valve and curbed area have been included in the site development plans. During Stormwater Site Plan Page 13 Arlington Electrical Equipment &Pole Storage Yard July, 2016 normal operations the transformer pavement area will drain onto the gravel section via a storm drain outlet and will be treated by the water quality section within the gravel section. The stormwater quality treatment design is discussed in more detail in Appendix C of this report. MR #7: Flow Control. All stormwater generated on the project site from the proposed impervious and pervious surfaces from 50% of the 2 year peak flow up to the full 50 year peak flow as modeled by WWHM2012 will infiltrate into the subgrade mimicking existing conditions. The long term infiltration rate of the subgrade soils has been established by grain size analysis conducted by GeoEngineers (see Geotechnical report dated May 4, 2016). GeoEngineers took several samples of the subgrade material at different locations and depths on the 26.5 acre site. The site soils are consistent briefly described as sand with a higher percentage of silt at lower depths. The proposed gravel section will require stripping a minimum of 2.5â€™ from the existing site for construction of the proposed section. The low long-term infiltration rate calculated by GeoEngineers is 1.2 inches/hour at 3 feet below existing grade. The high long-term infiltration rate calculated by GeoEngineers is 7.7 inches/hour at 6 feet below existing grade. For design of the infiltration facilities a conservative rate of 1.2 inches per hour was used to verify 100% infiltration and that ponding of water at the subgrade line did not backwater into the treatment section. The DOE Manual in Volume III, page 3-85 states that the base of all infiltration basins or trenches shall be greater or equal to 5 feet above the seasonal high water mark. This can be reduced to 3 feet with a groundwater mounding analysis. A Hydrogeologic Assessment was completed to support the site development and address this design constraint as well as discuss the sole source aquifer and it relates to the proposed site development in more detail. Two data loggers were installed and measured seasonal groundwater elevations during the rainy season for several years. In general terms the groundwater elevation from existing subgrade deepens from the south property line to the north. The maximum recorded groundwater elevation below existing grade near the middle of the site is approximately 7 feet. The maximum recorded groundwater elevation below existing grade near the south end of the site is approximately 4 feet. The proposed development borders the north property line and the bottom of the proposed facilities 2.5 feet below existing grade. Assuming the seasonal groundwater level deepens to the north the designed facilities have the required separation. This is consistent with visual observations of two stormwater ponds on the AAMP property which border the development to the north. See separate Hydrogeologic Assessment completed by GeoEngineers dated April 26, 2016 for additional information. Stormwater Site Plan Page 14 Arlington Electrical Equipment &Pole Storage Yard July, 2016 The imported materials that will be placed on the prepared subgrade in the gravel areas have a low percentage of fines and will not restrict infiltration of stormwater into the subgrade. The subgrade is the confining layer of material and the infiltration rate through this material was used in design. The stormwater infiltration design is discussed in more detail in Appendix B of this report. MR #8: Wetlands Protection There are no wetlands or wetland buffers impacting the site. MR #9: Basin/Watershed Planning. A portion of the site lies within a wellhead protection zone. A City of Arlington airport well is located approximately 2,000 feet north of the project site. The proposed gravel section with an 18 inch water quality section will provide adequate treatment of stormwater prior to infiltration reducing potential impacts to the water source. See Appendix D for wellhead protection zone map. MR #10: Operation and Maintenance. An Operation and Maintenance Manual is included in Appendix F of this report. Stormwater Site Plan Page 15 Arlington Electrical Equipment &Pole Storage Yard July, 2016 6.0 Stormwater Control Plan The following section details the selection of stormwater control BMPs and facilities that will serve the proposed project in its developed condition. The selection of stormwater control and BMP facilities follows the 2012 DOE Manual. Existing Site Hydrology The project site is 26.5-acres in area with an old dilapidated barn in the center of the property. Vegetation of the site consists of recently mowed grasses, scotch broom, blackberry and a few large deciduous and conifer trees. The site is predominately flat with slopes of approximately 2 percent. The north east corner of the site is the high side, and gently slopes to the west. The west side of the site at NE 59th Street is the low side of the site. Off-site flows are limited. Properties to the north and south are developed with existing site drainage systems. There is no observed runoff coming from the project site. Based on site observation and the geotechnical report, the majority of all stormwater runoff infiltrates into the existing soils. Refer to the Geotechnical Report prepared for this project for additional soils information. Developed Site Hydrology Developed site conditions will mimic existing site drainage conditions by infiltrating stormwater runoff into the existing subgrade. Only a portion of the 26.5 acre site will be developed for creation of the proposed Arlington Electrical Equipment and Pole Storage Yard. The developed yard is approximately 1.7 acres. During development an additional 1.5 acres will be disturbed for on-site disposal of organic strippings. The paved access drives sheet flow drainage into the pervious gravel sections for treatment prior to infiltration. The gravel areas have been designed to treat tributary pavement areas with an 18â€ water quality section. The site design also incorporates a paved, curbed area with an oil stop valve for transformer storage to reduce the risk of contaminating soil as a result of an accidental spill. During normal operations the transformer pavement area will drain onto the gravel section via a storm drain outlet and will be treated by the water quality section within the gravel section. Stormwater Site Plan Page 16 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Performance Standards and Goals The stormwater facilities have been designed using the Western Washington Hydrology Model Version 2012. The stormwater discharges match developed discharge durations to pre-developed durations for the range of pre-developed discharge rates from 50% of the 2-year peak flow up to the full 50-year peak flow. WWHM2012 is based on continuous simulation hydrology and according to the 2012 SMMWW is acceptable for sizing infiltration and water quality facilities in Western Washington. The pre-developed condition is assumed to be forested with Type A/B soils. For further detailed information concerning the design of the stormwater facilities reference Appendices B & C. Stormwater Site Plan Page 17 Arlington Electrical Equipment &Pole Storage Yard July, 2016 7.0 Stormwater Pollution Prevention Plan (SWPPP) A site specific SWPPP will be provided prior to construction. Stormwater Site Plan Page 18 Arlington Electrical Equipment &Pole Storage Yard July, 2016 8.0 Special Reports and Studies â€¢ Critical Area Reconnaissance - GeoEngineers, Inc., June 28, 2016. â€¢ Geotechnical Engineering Report - GeoEngineers, Inc., May 4, 2016 â€¢ Hydrogeologic Assessment - GeoEngineers, Inc., April 26, 2016 â€¢ Traffic Analysis â€“ Gibson Traffic Consultants, Inc., April 21, 2016 â€¢ AHERA Inspection Report â€“ Snohomish County PUD No. 1, July 14, 2014 â€¢ Cultural Resources Assessment - Cultural Resources Consultants, July 8, 2016 Stormwater Site Plan Page 19 Arlington Electrical Equipment &Pole Storage Yard July, 2016 9.0 Other Permits â€¢ City of Arlington Grading Permit â€¢ City of Arlington Zoning Permit â€¢ City of Arlington Civil Permit â€¢ Washington State Department of Ecology Construction Stormwater General Permit â€¢ SEPA Threshold Determination (Snohomish County PUD No. 1 Lead Agency) â€¢ City of Arlington Avigation Easement Stormwater Site Plan Page 20 Arlington Electrical Equipment &Pole Storage Yard July, 2016 Appendix A â€“ Improvement Plans Stormwater Site Plan Appendix A Arlington Electrical Equipment &Pole Storage Yard July, 2016 Lockey TE hydraulic closer sized to accommodate door. 09/22/2016 Appendix B â€“ Flow Control Stormwater Site Plan Appendix B Arlington Electrical Equipment &Pole Storage Yard July, 2016 Sedimentation and Erosion Control In our opinion, the erosion potential of the on-site soils is low to moderate. Construction activities, including stripping and grading, will expose soils to the erosion effects of wind and water. The amount and potential impacts of erosion are partly related to the time of year that construction actually occurs. Wet weather construction will increase the amount and extent of erosion and potential sedimentation. Erosion and sedimentation control measures may be implemented by using a combination of interceptor swales, straw bale barriers, silt fences and straw mulch for temporary erosion protection of exposed soils. All disturbed areas should be finish graded and seeded as soon as practicable to reduce the risk of erosion. Erosion and sedimentation control measures should be installed and maintained in accordance with the requirements of the City of Arlington. Infiltration Facilities We understand that the District is planning to design the unpaved gravel areas for stormwater infiltration at the site. We understand that the pole storage yard gravel surfacing section will be underlain by a bioretention soil mix layer for stormwater treatment. We also understand that infiltration requirements will be designed in accordance with the Washington State Department of Ecologyâ€™s 2012 SWMMWW. Since the soils have not been glacially consolidated, a pilot infiltration test (PIT) is not required in order to estimate an initial saturated hydraulic conductivity (Ksat) per Section 3.3.4 of the SWMMWW. The initial saturated hydraulic conductivity values were estimated using the grain size analysis method per Section 3.3.6 of the SWMMWW. We completed eight grain size analyses on selected samples from our explorations. The estimated long-term (factored) saturated hydraulic conductivity values for each sample is summarized in Table 5. TABLE 5. ESTIMATED LONG-TERM SATURATED HYDRAULIC CONDUCTIVITY Long-Term Rate (factored) Ksat USCS Depth D10 D60 D90 ffines Exploration Symbol (feet) (mm) (mm) (mm) (%) (cm/s) (in/hr) B-2 SP-SM 5 0.170 5.37 16.2 5.8 3.81 x 10-3 5.4 B-3 SM 2Â½ 0.040 0.61 8.6 13.2 1.62 x 10-3 2.3 B-5 SP-SM 5 0.100 3.07 25.5 8.1 1.76 x 10-3 2.5 TP-1 SP 6 0.120 0.31 0.7 3.7 4.52 x 10-3 6.4 TP-3 SP 6 0.230 1.22 13.3 2.6 5.43 x 10-3 7.7 TP-7 SP-SM 3 0.070 0.51 3.8 11.2 2.33 x 10-3 3.3 TP-8 SM 3 0.001 0.23 0.7 27.1 8.47 x 10-4 1.2 TP-8 SP 6 0.200 0.85 8.6 2.8 5.36 x 10-3 7.6 Notes: mm = millimeter; cm/s = centimeters per second; in/hr = inchers per hour Conservative Rate used for design May 4, 2016 | Page 12 File No. 0482-051-03 NORTH CENTER INFILTRATION AREA NORTH CENTER TRIBUTARY INFILTRATION AREA PAVEMENT AREA 5,746SF = 75.8^2SF 7,489 SF = 0.17AC WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Arlington (North Center) Site Name: PUD Pole Yard Site Address: 59th Ave NE City : Arlington Report Date: 10/3/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.20 Version Date: 2016/02/25 Version : 4.2.12 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : PreDev North Center Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .3 Pervious Total 0.3 Impervious Land Use acre Impervious Total 0 Basin Total 0.3 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : North Center Pervious Bottom Length: 75.80 ft. Bottom Width: 75.80 ft. Trench bottom slope 1: 0 To 1 Total gravel area is Trench Left side slope 0: 0 To 1 5,746 square feet Trench right side slope 2: 0 To 1 Material thickness of first layer: 0.6666666 Pour Space of material for first layer: 0.4 Material thickness of second layer: 1.5 Pour Space of material for second layer: 0.4 Material thickness of third layer: 0.333333 Pour Space of material for third layer: 0.4 Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 57.77 Total Volume Through Riser (ac-ft.): 0 No backwater into treatment layer Total Volume Through Facility (ac-ft.): 57.77 above 4 inches of rock at base of facility Percent Infiltrated: 100 Total Precip Applied to Facility: 26.715 Total Evap From Facility: 1.834 Discharge Structure Riser Height: 0.333333333 ft. Riser Diameter: 24 in. Precipitation applied to facility 5,746 sf 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 0.131 0.000 0.000 0.000 0.0148 0.131 0.000 0.000 0.159 0.0296 0.131 0.001 0.000 0.159 0.0444 0.131 0.002 0.000 0.159 0.0593 0.131 0.003 0.000 0.159 0.0741 0.131 0.003 0.000 0.159 0.0889 0.131 0.004 0.000 0.159 0.1037 0.131 0.005 0.000 0.159 0.1185 0.131 0.006 0.000 0.159 0.1333 0.131 0.007 0.000 0.159 0.1481 0.131 0.007 0.000 0.159 0.1630 0.131 0.008 0.000 0.159 0.1778 0.131 0.009 0.000 0.159 0.1926 0.131 0.010 0.000 0.159 0.2074 0.131 0.010 0.000 0.159 0.2222 0.131 0.011 0.000 0.159 0.2370 0.131 0.012 0.000 0.159 0.2519 0.131 0.013 0.000 0.159 0.2667 0.131 0.014 0.000 0.159 0.2815 0.131 0.014 0.000 0.159 0.2963 0.131 0.015 0.000 0.159 0.3111 0.131 0.016 0.000 0.159 0.3259 0.131 0.017 0.000 0.159 0.3407 0.131 0.018 0.013 0.159 0.3556 0.131 0.018 0.070 0.159 0.3704 0.131 0.019 0.151 0.159 0.3852 0.131 0.020 0.250 0.159 0.4000 0.131 0.021 0.365 0.159 0.4148 0.131 0.021 0.493 0.159 0.4296 0.131 0.022 0.633 0.159 0.4444 0.131 0.023 0.784 0.159 0.4593 0.131 0.024 0.946 0.159 0.4741 0.131 0.025 1.117 0.159 0.4889 0.131 0.025 1.297 0.159 0.5037 0.131 0.026 1.486 0.159 0.5185 0.131 0.027 1.682 0.159 0.5333 0.131 0.028 1.886 0.159 0.5481 0.131 0.028 2.097 0.159 0.5630 0.131 0.029 2.314 0.159 0.5778 0.131 0.030 2.537 0.159 0.5926 0.131 0.031 2.766 0.159 0.6074 0.131 0.032 3.000 0.159 0.6222 0.131 0.032 3.239 0.159 0.6370 0.131 0.033 3.482 0.159 0.6519 0.131 0.034 3.729 0.159 0.6667 0.131 0.035 3.979 0.159 0.6815 0.131 0.036 4.232 0.159 0.6963 0.131 0.036 4.487 0.159 0.7111 0.131 0.037 4.745 0.159 0.7259 0.131 0.038 5.004 0.159 0.7407 0.131 0.039 5.264 0.159 0.7556 0.131 0.039 5.525 0.159 0.7704 0.131 0.040 5.786 0.159 0.7852 0.131 0.041 6.047 0.159 0.8000 0.131 0.042 6.307 0.159 0.8148 0.131 0.043 6.566 0.159 0.8296 0.131 0.043 6.823 0.159 0.8444 0.131 0.044 7.078 0.159 0.8593 0.131 0.045 7.331 0.159 0.8741 0.131 0.046 7.580 0.159 0.8889 0.131 0.046 7.826 0.159 0.9037 0.131 0.047 8.068 0.159 0.9185 0.131 0.048 8.306 0.159 0.9333 0.131 0.049 8.540 0.159 0.9481 0.131 0.050 8.768 0.159 0.9630 0.131 0.050 8.991 0.159 0.9778 0.131 0.051 9.208 0.159 0.9926 0.131 0.052 9.419 0.159 1.0074 0.131 0.053 9.624 0.159 1.0222 0.131 0.053 9.823 0.159 1.0370 0.131 0.054 10.01 0.159 1.0518 0.131 0.055 10.20 0.159 1.0667 0.131 0.056 10.37 0.159 1.0815 0.131 0.057 10.54 0.159 1.0963 0.131 0.057 10.71 0.159 1.1111 0.131 0.058 10.86 0.159 1.1259 0.131 0.059 11.01 0.159 1.1407 0.131 0.060 11.15 0.159 1.1556 0.131 0.061 11.29 0.159 1.1704 0.131 0.061 11.41 0.159 1.1852 0.131 0.062 11.53 0.159 1.2000 0.131 0.063 11.65 0.159 1.2148 0.131 0.064 11.76 0.159 1.2296 0.131 0.064 11.86 0.159 1.2444 0.131 0.065 11.96 0.159 1.2593 0.131 0.066 12.05 0.159 1.2741 0.131 0.067 12.14 0.159 1.2889 0.131 0.068 12.22 0.159 1.3037 0.131 0.068 12.30 0.159 1.3185 0.131 0.069 12.38 0.159 ___________________________________________________________________ Name : Lateral I Basin 1 Bypass: No pavement tributuary to Impervious Land Use acre gravel area ROADS FLAT LAT 0.17 ___________________________________________________________________ Element Flows To: Outlet 1 Outlet 2 North Center Pervious ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.3 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.17 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000344 5 year 0.000747 10 year 0.001198 25 year 0.002092 50 year 0.003092 100 year 0.004485 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.000 1950 0.001 0.000 1951 0.000 0.000 1952 0.000 0.000 1953 0.000 0.000 1954 0.002 0.000 1955 0.001 0.000 1956 0.000 0.000 1957 0.000 0.000 1958 0.000 0.000 1959 0.001 0.000 1960 0.000 0.000 1961 0.001 0.000 1962 0.000 0.000 1963 0.000 0.000 1964 0.001 0.000 1965 0.000 0.000 1966 0.000 0.000 1967 0.000 0.000 1968 0.000 0.000 1969 0.000 0.000 1970 0.000 0.000 1971 0.001 0.000 1972 0.000 0.000 1973 0.000 0.000 1974 0.001 0.000 1975 0.000 0.000 1976 0.001 0.000 1977 0.000 0.000 1978 0.000 0.000 1979 0.000 0.000 1980 0.000 0.000 1981 0.000 0.000 1982 0.000 0.000 1983 0.000 0.000 1984 0.000 0.000 1985 0.000 0.000 1986 0.002 0.000 1987 0.001 0.000 1988 0.000 0.000 1989 0.000 0.000 1990 0.000 0.000 1991 0.000 0.000 1992 0.000 0.000 1993 0.000 0.000 1994 0.000 0.000 1995 0.000 0.000 1996 0.003 0.000 1997 0.007 0.000 1998 0.000 0.000 1999 0.000 0.000 2000 0.000 0.000 2001 0.000 0.000 2002 0.000 0.000 2003 0.000 0.000 2004 0.000 0.000 2005 0.000 0.000 2006 0.008 0.000 2007 0.000 0.000 2008 0.000 0.000 2009 0.000 0.000 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0080 0.0000 2 0.0074 0.0000 3 0.0027 0.0000 4 0.0021 0.0000 5 0.0017 0.0000 6 0.0014 0.0000 7 0.0013 0.0000 8 0.0012 0.0000 9 0.0011 0.0000 10 0.0008 0.0000 11 0.0007 0.0000 12 0.0006 0.0000 13 0.0005 0.0000 14 0.0005 0.0000 15 0.0005 0.0000 16 0.0005 0.0000 17 0.0005 0.0000 18 0.0004 0.0000 19 0.0004 0.0000 20 0.0004 0.0000 21 0.0004 0.0000 22 0.0004 0.0000 23 0.0003 0.0000 24 0.0002 0.0000 25 0.0002 0.0000 26 0.0002 0.0000 27 0.0002 0.0000 28 0.0002 0.0000 29 0.0002 0.0000 30 0.0002 0.0000 31 0.0002 0.0000 32 0.0002 0.0000 33 0.0002 0.0000 34 0.0002 0.0000 35 0.0002 0.0000 36 0.0002 0.0000 37 0.0002 0.0000 38 0.0002 0.0000 39 0.0002 0.0000 40 0.0002 0.0000 41 0.0002 0.0000 42 0.0002 0.0000 43 0.0002 0.0000 44 0.0002 0.0000 45 0.0002 0.0000 46 0.0002 0.0000 47 0.0002 0.0000 48 0.0002 0.0000 49 0.0002 0.0000 50 0.0002 0.0000 51 0.0002 0.0000 52 0.0002 0.0000 53 0.0002 0.0000 54 0.0002 0.0000 55 0.0002 0.0000 56 0.0002 0.0000 57 0.0002 0.0000 58 0.0002 0.0000 59 0.0002 0.0000 60 0.0002 0.0000 61 0.0002 0.0000 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0002 2363 0 0 Pass 0.0002 1352 0 0 Pass 0.0002 470 0 0 Pass 0.0003 112 0 0 Pass 0.0003 103 0 0 Pass 0.0003 89 0 0 Pass 0.0003 77 0 0 Pass 0.0004 66 0 0 Pass 0.0004 62 0 0 Pass 0.0004 58 0 0 Pass 0.0005 54 0 0 Pass 0.0005 50 0 0 Pass 0.0005 49 0 0 Pass 0.0006 47 0 0 Pass 0.0006 43 0 0 Pass 0.0006 40 0 0 Pass 0.0006 36 0 0 Pass 0.0007 36 0 0 Pass 0.0007 32 0 0 Pass 0.0007 31 0 0 Pass 0.0008 31 0 0 Pass 0.0008 29 0 0 Pass 0.0008 29 0 0 Pass 0.0009 27 0 0 Pass 0.0009 26 0 0 Pass 0.0009 26 0 0 Pass 0.0009 26 0 0 Pass 0.0010 25 0 0 Pass 0.0010 23 0 0 Pass 0.0010 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 21 0 0 Pass 0.0012 19 0 0 Pass 0.0012 18 0 0 Pass 0.0012 17 0 0 Pass 0.0013 16 0 0 Pass 0.0013 16 0 0 Pass 0.0013 15 0 0 Pass 0.0014 15 0 0 Pass 0.0014 14 0 0 Pass 0.0014 13 0 0 Pass 0.0014 13 0 0 Pass 0.0015 13 0 0 Pass 0.0015 13 0 0 Pass 0.0015 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0017 11 0 0 Pass 0.0017 11 0 0 Pass 0.0017 11 0 0 Pass 0.0018 11 0 0 Pass 0.0018 11 0 0 Pass 0.0018 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0021 10 0 0 Pass 0.0021 10 0 0 Pass 0.0021 9 0 0 Pass 0.0021 9 0 0 Pass 0.0022 8 0 0 Pass 0.0022 8 0 0 Pass 0.0022 8 0 0 Pass 0.0023 8 0 0 Pass 0.0023 8 0 0 Pass 0.0023 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 7 0 0 Pass 0.0026 7 0 0 Pass 0.0027 7 0 0 Pass 0.0027 7 0 0 Pass 0.0027 6 0 0 Pass 0.0028 6 0 0 Pass 0.0028 6 0 0 Pass 0.0028 6 0 0 Pass 0.0029 6 0 0 Pass 0.0029 6 0 0 Pass 0.0029 6 0 0 Pass 0.0029 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0031 5 0 0 Pass 0.0031 5 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 North Center Pervious POC N 52.61 N 99.92 Total Volume Infiltrated 52.61 0.00 0.00 99.92 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd 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 Â© by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. less than 4 inches SOUTH CENTER INFILTRATION AREA TRIBUTARY PAVEMENT AREA 6,181 SF = 0.14AC SOUTH CENTER INFILTRATION AREA 7,868SF = 88.7^2SF WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Arlington (South Center) Site Name: PUD Pole Yard Site Address: 59th Ave NE City : Arlington Report Date: 10/3/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.20 Version Date: 2016/02/25 Version : 4.2.12 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : PreDev South Center Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .32 Pervious Total 0.32 Impervious Land Use acre Impervious Total 0 Basin Total 0.32 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : South Center Pervious Bottom Length: 88.70 ft. Bottom Width: 88.70 ft. Trench bottom slope 1: 0 To 1 Total gravel area is Trench Left side slope 0: 0 To 1 7,868 square feet Trench right side slope 2: 0 To 1 Material thickness of first layer: 0.6666 Pour Space of material for first layer: 0.4 Material thickness of second layer: 1.5 Pour Space of material for second layer: 0.4 Material thickness of third layer: 0.3333 No backwater into treatment layer Pour Space of material for third layer: 0.4 above 4 inches of rock at base of facility Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 62.013 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 62.013 Percent Infiltrated: 100 Total Precip Applied to Facility: 37.219 Total Evap From Facility: 2.314 Discharge Structure Riser Height: 0.3333 ft. Precipitation applied to Riser Diameter: 24 in. facility 7,868 sf 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 0.180 0.000 0.000 0.000 0.0278 0.180 0.002 0.000 0.218 0.0556 0.180 0.004 0.000 0.218 0.0833 0.180 0.006 0.000 0.218 0.1111 0.180 0.008 0.000 0.218 0.1389 0.180 0.010 0.000 0.218 0.1667 0.180 0.012 0.000 0.218 0.1944 0.180 0.014 0.000 0.218 0.2222 0.180 0.016 0.000 0.218 0.2500 0.180 0.018 0.000 0.218 0.2778 0.180 0.020 0.000 0.218 0.3056 0.180 0.022 0.000 0.218 0.3333 0.180 0.024 0.000 0.218 0.3611 0.180 0.026 0.098 0.218 0.3889 0.180 0.028 0.278 0.218 0.4167 0.180 0.030 0.510 0.218 0.4444 0.180 0.032 0.785 0.218 0.4722 0.180 0.034 1.096 0.218 0.5000 0.180 0.036 1.438 0.218 0.5278 0.180 0.038 1.809 0.218 0.5556 0.180 0.040 2.205 0.218 0.5833 0.180 0.042 2.623 0.218 0.6111 0.180 0.044 3.060 0.218 0.6389 0.180 0.046 3.513 0.218 0.6667 0.180 0.048 3.979 0.218 0.6944 0.180 0.050 4.456 0.218 0.7222 0.180 0.052 4.940 0.218 0.7500 0.180 0.054 5.428 0.218 0.7778 0.180 0.056 5.917 0.218 0.8056 0.180 0.058 6.405 0.218 0.8333 0.180 0.060 6.888 0.218 0.8611 0.180 0.062 7.363 0.218 0.8889 0.180 0.064 7.827 0.218 0.9167 0.180 0.066 8.277 0.218 0.9444 0.180 0.068 8.712 0.218 0.9722 0.180 0.070 9.128 0.218 1.0000 0.180 0.072 9.523 0.218 1.0278 0.180 0.074 9.896 0.218 1.0556 0.180 0.076 10.24 0.218 1.0833 0.180 0.078 10.56 0.218 1.1111 0.180 0.080 10.86 0.218 1.1389 0.180 0.082 11.14 0.218 1.1667 0.180 0.084 11.38 0.218 1.1944 0.180 0.086 11.61 0.218 1.2222 0.180 0.088 11.81 0.218 1.2500 0.180 0.090 11.99 0.218 1.2778 0.180 0.092 12.16 0.218 1.3056 0.180 0.094 12.31 0.218 1.3333 0.180 0.096 12.59 0.218 1.3611 0.180 0.098 12.77 0.218 1.3889 0.180 0.100 12.94 0.218 1.4167 0.180 0.102 13.11 0.218 1.4444 0.180 0.104 13.28 0.218 1.4722 0.180 0.106 13.44 0.218 1.5000 0.180 0.108 13.60 0.218 1.5278 0.180 0.110 13.76 0.218 1.5556 0.180 0.112 13.92 0.218 1.5833 0.180 0.114 14.08 0.218 1.6111 0.180 0.116 14.24 0.218 1.6389 0.180 0.118 14.39 0.218 1.6667 0.180 0.120 14.54 0.218 1.6944 0.180 0.122 14.69 0.218 1.7222 0.180 0.124 14.84 0.218 1.7500 0.180 0.126 14.99 0.218 1.7778 0.180 0.128 15.14 0.218 1.8056 0.180 0.130 15.28 0.218 1.8333 0.180 0.132 15.43 0.218 1.8611 0.180 0.134 15.57 0.218 1.8889 0.180 0.136 15.71 0.218 1.9167 0.180 0.138 15.85 0.218 1.9444 0.180 0.140 15.99 0.218 1.9722 0.180 0.142 16.12 0.218 2.0000 0.180 0.144 16.26 0.218 2.0278 0.180 0.146 16.40 0.218 2.0556 0.180 0.148 16.53 0.218 2.0833 0.180 0.150 16.66 0.218 2.1111 0.180 0.152 16.79 0.218 2.1389 0.180 0.154 16.92 0.218 2.1667 0.180 0.156 17.05 0.218 2.1944 0.180 0.158 17.18 0.218 2.2222 0.180 0.160 17.31 0.218 2.2500 0.180 0.162 17.44 0.218 2.2778 0.180 0.164 17.56 0.218 2.3056 0.180 0.166 17.69 0.218 2.3333 0.180 0.168 17.81 0.218 2.3611 0.180 0.170 17.94 0.218 2.3889 0.180 0.172 18.06 0.218 2.4167 0.180 0.174 18.18 0.218 2.4444 0.180 0.176 18.30 0.218 2.4722 0.180 0.178 18.42 0.218 2.5000 0.180 0.183 18.54 0.218 ___________________________________________________________________ Name : Impervious Bypass: No pavement tributuary to Impervious Land Use acre gravel area ROADS FLAT LAT 0.14 ___________________________________________________________________ Element Flows To: Outlet 1 Outlet 2 South Center Pervious ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.32 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.14 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000367 5 year 0.000797 10 year 0.001278 25 year 0.002232 50 year 0.003298 100 year 0.004784 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.000 1950 0.001 0.000 1951 0.001 0.000 1952 0.000 0.000 1953 0.000 0.000 1954 0.002 0.000 1955 0.001 0.000 1956 0.000 0.000 1957 0.000 0.000 1958 0.000 0.000 1959 0.001 0.000 1960 0.000 0.000 1961 0.001 0.000 1962 0.000 0.000 1963 0.000 0.000 1964 0.001 0.000 1965 0.000 0.000 1966 0.000 0.000 1967 0.000 0.000 1968 0.000 0.000 1969 0.000 0.000 1970 0.000 0.000 1971 0.001 0.000 1972 0.000 0.000 1973 0.000 0.000 1974 0.001 0.000 1975 0.000 0.000 1976 0.001 0.000 1977 0.000 0.000 1978 0.000 0.000 1979 0.001 0.000 1980 0.000 0.000 1981 0.000 0.000 1982 0.000 0.000 1983 0.000 0.000 1984 0.000 0.000 1985 0.000 0.000 1986 0.002 0.000 1987 0.001 0.000 1988 0.000 0.000 1989 0.000 0.000 1990 0.000 0.000 1991 0.000 0.000 1992 0.000 0.000 1993 0.000 0.000 1994 0.000 0.000 1995 0.000 0.000 1996 0.003 0.000 1997 0.008 0.000 1998 0.000 0.000 1999 0.000 0.000 2000 0.000 0.000 2001 0.000 0.000 2002 0.000 0.000 2003 0.000 0.000 2004 0.000 0.000 2005 0.000 0.000 2006 0.009 0.000 2007 0.000 0.000 2008 0.000 0.000 2009 0.000 0.000 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0085 0.0000 2 0.0079 0.0000 3 0.0029 0.0000 4 0.0023 0.0000 5 0.0018 0.0000 6 0.0015 0.0000 7 0.0013 0.0000 8 0.0012 0.0000 9 0.0012 0.0000 10 0.0008 0.0000 11 0.0007 0.0000 12 0.0007 0.0000 13 0.0006 0.0000 14 0.0006 0.0000 15 0.0005 0.0000 16 0.0005 0.0000 17 0.0005 0.0000 18 0.0005 0.0000 19 0.0005 0.0000 20 0.0004 0.0000 21 0.0004 0.0000 22 0.0004 0.0000 23 0.0003 0.0000 24 0.0003 0.0000 25 0.0003 0.0000 26 0.0003 0.0000 27 0.0003 0.0000 28 0.0003 0.0000 29 0.0003 0.0000 30 0.0003 0.0000 31 0.0003 0.0000 32 0.0003 0.0000 33 0.0003 0.0000 34 0.0003 0.0000 35 0.0003 0.0000 36 0.0003 0.0000 37 0.0003 0.0000 38 0.0003 0.0000 39 0.0003 0.0000 40 0.0003 0.0000 41 0.0003 0.0000 42 0.0003 0.0000 43 0.0003 0.0000 44 0.0003 0.0000 45 0.0003 0.0000 46 0.0003 0.0000 47 0.0003 0.0000 48 0.0003 0.0000 49 0.0003 0.0000 50 0.0003 0.0000 51 0.0003 0.0000 52 0.0003 0.0000 53 0.0003 0.0000 54 0.0003 0.0000 55 0.0002 0.0000 56 0.0002 0.0000 57 0.0002 0.0000 58 0.0002 0.0000 59 0.0002 0.0000 60 0.0002 0.0000 61 0.0002 0.0000 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0002 2391 0 0 Pass 0.0002 1364 0 0 Pass 0.0002 450 0 0 Pass 0.0003 112 0 0 Pass 0.0003 103 0 0 Pass 0.0003 89 0 0 Pass 0.0004 77 0 0 Pass 0.0004 66 0 0 Pass 0.0004 61 0 0 Pass 0.0005 58 0 0 Pass 0.0005 54 0 0 Pass 0.0005 50 0 0 Pass 0.0006 49 0 0 Pass 0.0006 47 0 0 Pass 0.0006 43 0 0 Pass 0.0007 40 0 0 Pass 0.0007 36 0 0 Pass 0.0007 36 0 0 Pass 0.0007 32 0 0 Pass 0.0008 31 0 0 Pass 0.0008 31 0 0 Pass 0.0008 29 0 0 Pass 0.0009 29 0 0 Pass 0.0009 27 0 0 Pass 0.0009 26 0 0 Pass 0.0010 26 0 0 Pass 0.0010 26 0 0 Pass 0.0010 25 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0011 23 0 0 Pass 0.0012 23 0 0 Pass 0.0012 23 0 0 Pass 0.0012 21 0 0 Pass 0.0013 19 0 0 Pass 0.0013 18 0 0 Pass 0.0013 17 0 0 Pass 0.0013 16 0 0 Pass 0.0014 16 0 0 Pass 0.0014 15 0 0 Pass 0.0014 15 0 0 Pass 0.0015 14 0 0 Pass 0.0015 13 0 0 Pass 0.0015 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0016 13 0 0 Pass 0.0017 13 0 0 Pass 0.0017 13 0 0 Pass 0.0017 13 0 0 Pass 0.0018 13 0 0 Pass 0.0018 11 0 0 Pass 0.0018 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0019 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0020 11 0 0 Pass 0.0021 11 0 0 Pass 0.0021 11 0 0 Pass 0.0021 11 0 0 Pass 0.0022 11 0 0 Pass 0.0022 11 0 0 Pass 0.0022 10 0 0 Pass 0.0023 9 0 0 Pass 0.0023 9 0 0 Pass 0.0023 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0024 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0025 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 8 0 0 Pass 0.0026 8 0 0 Pass 0.0027 8 0 0 Pass 0.0027 8 0 0 Pass 0.0027 8 0 0 Pass 0.0028 8 0 0 Pass 0.0028 7 0 0 Pass 0.0028 7 0 0 Pass 0.0029 7 0 0 Pass 0.0029 7 0 0 Pass 0.0029 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0030 6 0 0 Pass 0.0031 6 0 0 Pass 0.0031 6 0 0 Pass 0.0031 6 0 0 Pass 0.0032 6 0 0 Pass 0.0032 6 0 0 Pass 0.0032 6 0 0 Pass 0.0033 5 0 0 Pass 0.0033 5 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 South Center Pervious POC N 56.46 N 99.96 Total Volume Infiltrated 56.46 0.00 0.00 99.96 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd 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 Â© by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. less than 4 inches PERIMETER INFILTRATION AREA TRIBUTARY PAVEMENT AREA 11,063 SF = 0.25AC PERIMETER INFILTRATION AREA 31,223SF = 176.70^2SF WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Arlington (Perimeter) Site Name: PUD Pole Yard Site Address: 59th Ave NE City : Arlington Report Date: 10/3/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.20 Version Date: 2016/02/25 Version : 4.2.12 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : PreDev Perimeter Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .96 Pervious Total 0.96 Impervious Land Use acre Impervious Total 0 Basin Total 0.96 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : North Center Pervious Bottom Length: 176.70 ft. Bottom Width: 176.70 ft. Trench bottom slope 1: 0 To 1 Total gravel area is Trench Left side slope 0: 0 To 1 31,223 square feet Trench right side slope 2: 0 To 1 Material thickness of first layer: 0.66666 Pour Space of material for first layer: 0.4 Material thickness of second layer: 1.5 Pour Space of material for second layer: 0.4 No backwater into treatment layer Material thickness of third layer: 0.333 above 4 inches of rock at base of facility Pour Space of material for third layer: 0.4 Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 186.463 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 186.463 Percent Infiltrated: 100 Total Precip Applied to Facility: 145.611 Total Evap From Facility: 7.569 Discharge Structure Riser Height: 0.3333 ft. Precipitation applied to Riser Diameter: 24 in. facility 31,223 sf 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 0.716 0.000 0.000 0.000 0.0278 0.716 0.008 0.000 0.867 0.0556 0.716 0.015 0.000 0.867 0.0833 0.716 0.023 0.000 0.867 0.1111 0.716 0.031 0.000 0.867 0.1389 0.716 0.039 0.000 0.867 0.1667 0.716 0.047 0.000 0.867 0.1944 0.716 0.055 0.000 0.867 0.2222 0.716 0.063 0.000 0.867 0.2500 0.716 0.071 0.000 0.867 0.2778 0.716 0.079 0.000 0.867 0.3056 0.716 0.087 0.000 0.867 0.3333 0.716 0.095 0.000 0.867 0.3611 0.716 0.103 0.098 0.867 0.3889 0.716 0.111 0.278 0.867 0.4167 0.716 0.119 0.510 0.867 0.4444 0.716 0.127 0.785 0.867 0.4722 0.716 0.135 1.096 0.867 0.5000 0.716 0.143 1.438 0.867 0.5278 0.716 0.151 1.809 0.867 0.5556 0.716 0.159 2.205 0.867 0.5833 0.716 0.167 2.623 0.867 0.6111 0.716 0.175 3.060 0.867 0.6389 0.716 0.183 3.513 0.867 0.6667 0.716 0.191 3.979 0.867 0.6944 0.716 0.199 4.456 0.867 0.7222 0.716 0.207 4.940 0.867 0.7500 0.716 0.215 5.428 0.867 0.7778 0.716 0.223 5.917 0.867 0.8056 0.716 0.231 6.405 0.867 0.8333 0.716 0.238 6.888 0.867 0.8611 0.716 0.246 7.363 0.867 0.8889 0.716 0.254 7.827 0.867 0.9167 0.716 0.262 8.277 0.867 0.9444 0.716 0.270 8.712 0.867 0.9722 0.716 0.278 9.128 0.867 1.0000 0.716 0.286 9.523 0.867 1.0278 0.716 0.294 9.896 0.867 1.0556 0.716 0.302 10.24 0.867 1.0833 0.716 0.310 10.56 0.867 1.1111 0.716 0.318 10.86 0.867 1.1389 0.716 0.326 11.14 0.867 1.1667 0.716 0.334 11.38 0.867 1.1944 0.716 0.342 11.61 0.867 1.2222 0.716 0.350 11.81 0.867 1.2500 0.716 0.358 11.99 0.867 1.2778 0.716 0.366 12.16 0.867 1.3056 0.716 0.374 12.31 0.867 1.3333 0.716 0.382 12.59 0.867 1.3611 0.716 0.390 12.77 0.867 1.3889 0.716 0.398 12.94 0.867 1.4167 0.716 0.406 13.11 0.867 1.4444 0.716 0.414 13.28 0.867 1.4722 0.716 0.422 13.44 0.867 1.5000 0.716 0.430 13.60 0.867 1.5278 0.716 0.438 13.76 0.867 1.5556 0.716 0.446 13.92 0.867 1.5833 0.716 0.454 14.08 0.867 1.6111 0.716 0.461 14.24 0.867 1.6389 0.716 0.469 14.39 0.867 1.6667 0.716 0.477 14.54 0.867 1.6944 0.716 0.485 14.69 0.867 1.7222 0.716 0.493 14.84 0.867 1.7500 0.716 0.501 14.99 0.867 1.7778 0.716 0.509 15.14 0.867 1.8056 0.716 0.517 15.28 0.867 1.8333 0.716 0.525 15.43 0.867 1.8611 0.716 0.533 15.57 0.867 1.8889 0.716 0.541 15.71 0.867 1.9167 0.716 0.549 15.85 0.867 1.9444 0.716 0.557 15.99 0.867 1.9722 0.716 0.565 16.12 0.867 2.0000 0.716 0.573 16.26 0.867 2.0278 0.716 0.581 16.40 0.867 2.0556 0.716 0.589 16.53 0.867 2.0833 0.716 0.597 16.66 0.867 2.1111 0.716 0.605 16.79 0.867 2.1389 0.716 0.613 16.92 0.867 2.1667 0.716 0.621 17.05 0.867 2.1944 0.716 0.629 17.18 0.867 2.2222 0.716 0.637 17.31 0.867 2.2500 0.716 0.645 17.44 0.867 2.2778 0.716 0.653 17.56 0.867 2.3056 0.716 0.661 17.69 0.867 2.3333 0.716 0.669 17.81 0.867 2.3611 0.716 0.677 17.94 0.867 2.3889 0.716 0.684 18.06 0.867 2.4167 0.716 0.692 18.18 0.867 2.4444 0.716 0.700 18.30 0.867 2.4722 0.716 0.708 18.42 0.867 2.5000 0.716 0.728 18.54 0.867 ___________________________________________________________________ Name : Lateral I Basin 1 Bypass: No pavement tributuary to Impervious Land Use acre gravel area ROADS FLAT LAT 0.25 ___________________________________________________________________ Element Flows To: Outlet 1 Outlet 2 North Center Pervious ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.96 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.25 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.001102 5 year 0.00239 10 year 0.003834 25 year 0.006695 50 year 0.009894 100 year 0.014351 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.001 0.000 1950 0.002 0.000 1951 0.002 0.000 1952 0.001 0.000 1953 0.001 0.000 1954 0.005 0.000 1955 0.004 0.000 1956 0.001 0.000 1957 0.001 0.000 1958 0.001 0.000 1959 0.002 0.000 1960 0.001 0.000 1961 0.004 0.000 1962 0.001 0.000 1963 0.001 0.000 1964 0.003 0.000 1965 0.001 0.000 1966 0.001 0.000 1967 0.001 0.000 1968 0.001 0.000 1969 0.001 0.000 1970 0.001 0.000 1971 0.004 0.000 1972 0.001 0.000 1973 0.001 0.000 1974 0.002 0.000 1975 0.001 0.000 1976 0.002 0.000 1977 0.001 0.000 1978 0.001 0.000 1979 0.002 0.000 1980 0.001 0.000 1981 0.001 0.000 1982 0.001 0.000 1983 0.001 0.000 1984 0.001 0.000 1985 0.001 0.000 1986 0.007 0.000 1987 0.004 0.000 1988 0.001 0.000 1989 0.001 0.000 1990 0.001 0.000 1991 0.001 0.000 1992 0.001 0.000 1993 0.001 0.000 1994 0.001 0.000 1995 0.001 0.000 1996 0.009 0.000 1997 0.024 0.000 1998 0.001 0.000 1999 0.001 0.000 2000 0.001 0.000 2001 0.001 0.000 2002 0.001 0.000 2003 0.001 0.000 2004 0.001 0.000 2005 0.001 0.000 2006 0.026 0.000 2007 0.001 0.000 2008 0.001 0.000 2009 0.001 0.000 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0256 0.0000 2 0.0238 0.0000 3 0.0087 0.0000 4 0.0068 0.0000 5 0.0053 0.0000 6 0.0044 0.0000 7 0.0040 0.0000 8 0.0037 0.0000 9 0.0036 0.0000 10 0.0025 0.0000 11 0.0022 0.0000 12 0.0020 0.0000 13 0.0017 0.0000 14 0.0017 0.0000 15 0.0016 0.0000 16 0.0015 0.0000 17 0.0015 0.0000 18 0.0014 0.0000 19 0.0014 0.0000 20 0.0013 0.0000 21 0.0012 0.0000 22 0.0011 0.0000 23 0.0009 0.0000 24 0.0008 0.0000 25 0.0008 0.0000 26 0.0008 0.0000 27 0.0008 0.0000 28 0.0008 0.0000 29 0.0008 0.0000 30 0.0008 0.0000 31 0.0008 0.0000 32 0.0008 0.0000 33 0.0008 0.0000 34 0.0008 0.0000 35 0.0008 0.0000 36 0.0008 0.0000 37 0.0008 0.0000 38 0.0008 0.0000 39 0.0008 0.0000 40 0.0008 0.0000 41 0.0008 0.0000 42 0.0008 0.0000 43 0.0008 0.0000 44 0.0008 0.0000 45 0.0008 0.0000 46 0.0008 0.0000 47 0.0008 0.0000 48 0.0008 0.0000 49 0.0008 0.0000 50 0.0008 0.0000 51 0.0008 0.0000 52 0.0008 0.0000 53 0.0008 0.0000 54 0.0008 0.0000 55 0.0007 0.0000 56 0.0007 0.0000 57 0.0007 0.0000 58 0.0007 0.0000 59 0.0007 0.0000 60 0.0007 0.0000 61 0.0005 0.0000 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0006 2355 0 0 Pass 0.0006 1329 0 0 Pass 0.0007 438 0 0 Pass 0.0008 112 0 0 Pass 0.0009 103 0 0 Pass 0.0010 89 0 0 Pass 0.0011 77 0 0 Pass 0.0012 66 0 0 Pass 0.0013 61 0 0 Pass 0.0014 58 0 0 Pass 0.0015 54 0 0 Pass 0.0016 50 0 0 Pass 0.0017 49 0 0 Pass 0.0018 47 0 0 Pass 0.0019 43 0 0 Pass 0.0020 40 0 0 Pass 0.0021 36 0 0 Pass 0.0022 36 0 0 Pass 0.0022 32 0 0 Pass 0.0023 31 0 0 Pass 0.0024 31 0 0 Pass 0.0025 29 0 0 Pass 0.0026 29 0 0 Pass 0.0027 27 0 0 Pass 0.0028 26 0 0 Pass 0.0029 26 0 0 Pass 0.0030 26 0 0 Pass 0.0031 25 0 0 Pass 0.0032 23 0 0 Pass 0.0033 23 0 0 Pass 0.0034 23 0 0 Pass 0.0035 23 0 0 Pass 0.0036 23 0 0 Pass 0.0037 21 0 0 Pass 0.0038 19 0 0 Pass 0.0039 18 0 0 Pass 0.0039 17 0 0 Pass 0.0040 16 0 0 Pass 0.0041 16 0 0 Pass 0.0042 15 0 0 Pass 0.0043 15 0 0 Pass 0.0044 14 0 0 Pass 0.0045 13 0 0 Pass 0.0046 13 0 0 Pass 0.0047 13 0 0 Pass 0.0048 13 0 0 Pass 0.0049 13 0 0 Pass 0.0050 13 0 0 Pass 0.0051 13 0 0 Pass 0.0052 13 0 0 Pass 0.0053 13 0 0 Pass 0.0054 11 0 0 Pass 0.0055 11 0 0 Pass 0.0056 11 0 0 Pass 0.0056 11 0 0 Pass 0.0057 11 0 0 Pass 0.0058 11 0 0 Pass 0.0059 11 0 0 Pass 0.0060 11 0 0 Pass 0.0061 11 0 0 Pass 0.0062 11 0 0 Pass 0.0063 11 0 0 Pass 0.0064 11 0 0 Pass 0.0065 11 0 0 Pass 0.0066 10 0 0 Pass 0.0067 10 0 0 Pass 0.0068 9 0 0 Pass 0.0069 9 0 0 Pass 0.0070 8 0 0 Pass 0.0071 8 0 0 Pass 0.0072 8 0 0 Pass 0.0073 8 0 0 Pass 0.0073 8 0 0 Pass 0.0074 8 0 0 Pass 0.0075 8 0 0 Pass 0.0076 8 0 0 Pass 0.0077 8 0 0 Pass 0.0078 8 0 0 Pass 0.0079 8 0 0 Pass 0.0080 8 0 0 Pass 0.0081 8 0 0 Pass 0.0082 8 0 0 Pass 0.0083 8 0 0 Pass 0.0084 7 0 0 Pass 0.0085 7 0 0 Pass 0.0086 7 0 0 Pass 0.0087 7 0 0 Pass 0.0088 6 0 0 Pass 0.0089 6 0 0 Pass 0.0090 6 0 0 Pass 0.0090 6 0 0 Pass 0.0091 6 0 0 Pass 0.0092 6 0 0 Pass 0.0093 6 0 0 Pass 0.0094 6 0 0 Pass 0.0095 6 0 0 Pass 0.0096 6 0 0 Pass 0.0097 6 0 0 Pass 0.0098 5 0 0 Pass 0.0099 5 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 North Center Pervious POC N 169.70 N 99.99 Total Volume Infiltrated 169.70 0.00 0.00 99.99 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd 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 Â© by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. less than 4 inches Appendix C â€“ Runoff Treatment Stormwater Site Plan Appendix C Arlington Electrical Equipment &Pole Storage Yard July, 2016 8410 154th Avenue NE Redmond, Washington 98052 425.861.6000 August 16, 2016 Snohomish County PUD No. 1 Facilities Department 2323 California Street P.O. Box 1107 Everett, Washington 98206 Attention: Ben Davis, PE Subject: Custom Bioretention Soil Mix Proposed Pole Storage Yard Arlington Site Development Arlington, Washington File No. 0482-051-03 INTRODUCTION This letter contains the laboratory testing results and recommendations for a custom bioretention soil mix for use in the design and construction of the proposed Pole Storage Yard at the Districtâ€™s Arlington Site located between 172nd Street NE and 180th Street NE off of 59th Avenue NE in Arlington, Washington. GeoEngineers previously prepared a geotechnical report for the project titled, â€œGeotechnical Engineering Services, Proposed Pole Storage Yard, Arlington Site Development, Arlington, Washington,â€ dated May 4, 2016. Project Description We understand that a portion of the Arlington property is being developed for a Pole Storage Yard to store treated poles and transformers. Development of the pole storage yard will include constructing gravel laydown areas, asphalt paved access roads and transformer storage areas, and installation of a water line. We understand that the native soils do not meet the minimum requirements for treatment of stormwater infiltration at the site. In order to meet storm water guidelines, the District is looking at using an imported amended soil mix that will be placed below the pole storage yard surfacing gravel to improve treatment of stormwater infiltration. The amended material will need to support occasional truck traffic loads, therefore the Default Bioretention Soil Media (BSM) standard 60/40 compost soil mix (by volume) from the 2014 Stormwater Management Manual for Western Washington (SWMMWW) will not be sufficient from a structural support standpoint. Snohomish County PUD No. 1 | August 16, 2016 Page 2 Purpose and Scope The purpose of our engineering services is to develop a custom bioretention soil using a compost and gravel borrow mixture which will: (1) meet the 2014 SWMMWW requirements for a custom bioretention soil mix and (2) provide support for occasional truck traffic. CUSTOM BIORETENTION SOIL MIX REQUIREMENTS We understand that the 2014 SWMMWW allows for development of a custom bioretention soil mix. The SWMMWW lists the following criteria for a custom soil mix: â– Cation-exchange capacity (CEC) â‰¥ 5 milliequivalents/100 grams of dry soil; USEPA 9081. â– pH between 5.5 and 7.0. â– 5 to 8 percent organic matter content (by weight) before and after the saturated hydraulic conductivity test (ASTM D 2974). â– 2 to 5 percent fines passing the U.S. Standard No. 200 sieve â– Measured (initial) saturated hydraulic conductivity of less than 12 inches per hour; ASTM D 2434 (constant head) at 85 percent and 90 percent compaction (ASTM D 1557) as modified by Appendix V-B of the SWMMWW. â– Design (long-term) saturated hydraulic conductivity of more than 1 inch per hour. â– Compost to meet requirements of Volume V of the SWMMWW. SAMPLES FOR TESTING Gravel borrow and compost samples were collected from Lenz Enterprises, Inc. on June 15, 2016. Grain size analysis test results for the gravel borrow are presented in Appendix A. The borrow sample material meets the Washington State Department of Transportation (WSDOT) requirements for gravel borrow and is classified as a poorly graded sand with gravel with 4 percent passing the 200 sieve. The technical data sheet for the compost material that we received is presented in Appendix A (Figure A-1). File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 3 LABORATORY TESTING CEC Testing Cation Exchange Capacity (CEC) testing was performed following USEPA 9081 on a 5, 10, 15 and 20 percent compost to gravel borrow mix. The CEC test results are presented in Appendix A and are shown on the plot below. 10 9 8 7 6 5 4 3 CEC (meq/100grm) 2 1 0 0 5 10 15 20 25 Percent Compost by Weight pH Testing pH testing was performed on a 5, 10, 15 and 20 percent compost to gravel borrow mix. The pH test results are shown on the plot below. pH tests were also performed on the gravel borrow (pH = 6.1) and the compost (pH = 8.2) for baseline purposes. 10 9 8 7 6 pH5 4 3 2 1 0 0 5 10 15 20 25 Percent Compost by Weight File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 4 Organic Content Testing Organic content testing was performed following ASTM D 2974 on a 5, 10, 15 and 20 percent compost to gravel borrow mix prior to conducting the saturated hydraulic conductivity tests. One organic content test was performed on the 15 percent compost to gravel borrow mix following the saturated hydraulic conductivity test. The organic content test results are shown on the plot below. 10 9 8 7 6 5 4 3 2 Organic Content (percent)1 0 0 5 10 15 20 25 Percent Compost by Weight Before Hydraulic Conductivity Test After Hydraulic Conductivity Test Grain Size Analysis Grain size analysis testing was performed following ASTM D 6913 on the gravel borrow sample, the 10, 15 and 20 percent compost to gravel borrow mix. The grain size analysis test results are presented in Appendix A (Figure A-2). Proctor Testing Laboratory compaction testing was performed following ASTM D 1157 on the 10, 15 and 20 percent compost to gravel borrow mix designs. The laboratory compaction test results are presented in Appendix A (Figures A-3 through A-5) and the measured maximum dry density (MDD) test results are shown on the plot below. 128 126 124 122 120 118 116 114 112 110 108 Maximum Dry Density (pcf) 106 0 5 10 15 20 25 Percent Compost by Weight Uncorrected With Rock Correction File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 5 Saturated Hydraulic Conductivity Testing Saturated hydraulic conductivity testing was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 SWMMWW at 85 percent compaction (ASTM D 1557). The tests were completed on samples compacted at 85 and 90 percent of the MDD, respectively. The measured (initial) saturated hydraulic conductivity test results are presented in Appendix A (Figures A-6 through A-8) and are summarized on the plot below. 25 85% Compaction 20 90% Compaction 15 10 5 Measured (initial) saturated hydraulic conductivity (in/hour) 0 0 5 10 15 20 25 Percent Compost by Weight The 2014 SWMMWW recommends a factor of safety of 4.0 for the design hydraulic conductivity value. The design (long-term) saturated hydraulic conductivity values with an applied safety factor of 4.0 is shown in the plot below for the samples compacted at 85 and 90 percent of the MDD. 7 6 85% Compaction 90% Compaction 5 4 -term) saturated 3 2 1 Design (long hydraulic conductivity (in/hour) 0 0 5 10 15 20 25 Percent Compost by Weight CONCLUSIONS AND RECOMMENDATIONS Based on the results of the laboratory testing, the 15 percent compost to gravel borrow mix meets the requirements of the 2014 SWMMWW Design Criteria for Custom Bioretention Soil Mixes, with the exception of the pH values, which were slightly higher than the 7.0 maximum requirement. The pH of the tested File No. 0000-001-00 File No. 0482-051-03 Snohomish County PUD No. 1 | August 16, 2016 Page 6 compost sample was 8.2. For the project specifications, we recommend compost with a pH between 5 and 7 be used for the bioretention soil mix in order to meet the SWMMWW design criteria. We recommend that the project specifications require gravel borrow be amended with 15 percent compost by weight for the custom bioretention soil mix below the gravel surfaced Pole Storage Yard. The gravel borrow should meet the requirements of section 9-03.14(1) of the 2016 WSDOT Standard Specifications. The compost should meet the requirements of the 2014 SWMMWW for bioretention. The materials should be adequately mixed to provide a uniform blended soil. The project specifications should require the contractor submit samples of their proposed custom bioretention soil mix for testing and verification purposes. GeoEngineers should test the submitted samples to confirm that the requirements of 2014 SWMMWW are satisfied (BMP T7.30, Design Criteria for Custom Bioretention Soil Mixes). A minimum 18-inch layer of the custom bioretention soil mix should be placed and compacted in areas designated for stormwater treatment. We recommend the bioretention soil mix be compacted in maximum 12 inch loose lifts to at least 85 percent of the MDD (corrected for gravel content) as determined by ASTM D 1557. This compaction effort is less than the standard of practice for support of traffic, therefore, periodic maintenance may be needed to repair rutting within the gravel surfacing if occasional vehicles are routed over these unpaved areas. The bioretention soil mix should not be placed below the asphalt or concrete paved areas of the site. In our opinion, a geotextile separation fabric is not needed above or below the bioretention gravel borrow mix, provided the bioretention soil is prepared as described above. The subgrade conditions and gravel surfacing recommendations provided in our May 4, 2016 geotechnical report should be followed. Although our proposed bioretention soil mix satisfies the 2014 SWMMWW design criteria for stormwater treatment, the structural capacity of the mix is limited because of the organic content and compaction criteria, and is not intended for support of significant equipment traffic. LIMITATIONS We have prepared this report for Snohomish County PUD No. 1. Copies of this report may be distributed to authorized agents and regulatory agencies as may be required for the project. Our evaluation pertains only to the physical properties of soil mechanics and hydrogeology as it pertains to the requirements of the 2014 SWMMWW design criteria. Chemical and treatment efficacy of the bioretention soil mix was not included in our scope of services. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. The conclusions, recommendations, and opinions presented in this report are based on our professional knowledge, judgment, laboratory test results, and experience. No warranty or other conditions, express or implied, should be understood. Any electronic form, facsimile or hard copy of the original document (email, text, table and/or figure), if provided, and any attachments should be considered a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record. File No. 0000-001-00 File No. 0482-051-03 APPENDIX A Laboratory Test Results 0482-051-03 Date Exported: 06/24/16 U.S. STANDARD SIEVE SIZE 3â€ 1.5â€ 3/4â€ 3/8â€ #4 #10 #20 #40 #60 #100 #200 100 90 80 70 60 PERCENT PASSING BY WEIGHT 50 40 30 20 10 0 Proposed Pole Storage Yard 1000 100 10 1 0.1 0.01 0.001 Sieve Analysis Results GRAIN SIZE IN MILLIMETERS Arlington, WA GRAVEL SAND COBBLES SILT OR CLAY COARSE FINE COARSE MEDIUM FINE Depth Moisture Symbol Sample (feet) (%) Soil Description No Compost N/A 5.4 Poorly graded sand with gravel (SP) Figure A 10% Compost N/A 8.0 Poorly graded sand with gravel and organic matter (SP) 15% Compost N/A 8.2 Poorly graded sand with silt and gravel and organic matter (SP-SM) 20% Compost N/A 12.1 Poorly graded sand with gravel and organic matter (SP) -2 Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they were performed,andshouldnotbe interpreted as representativeofanyothersamples obtained atother times,depthsorlocations,orgenerated by separate operationsorprocesses. Thegrainsizeanalysis results were obtained in general accordancewithASTMD6913. MOISTURE CONTENT (%) 0 5 10 15 20 25 30 140 135 130 125 (pcf) 120 DRY DENSITY 115 100% Saturation 110 (Gs=2.65) 105 100 Optimum Maximum Depth Moisture Dry Density Symbol Sample (feet) Soil Description (%) (pcf) Corrected 10% 9.9 127.1 N/A 10 Percent Compost/Gravel Borrow Mix Uncorrected Compost 13.5 116.0 Note: This report may not be reproduced, except in full, without written approval Compaction Test Results of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they were performed, and should not be interpreted as 10% Compost Mix representative of any other samples obtained at other times, depths or locations,orgenerated by separate operationsorprocesses. Proposed Pole Storage Yard The Proctor results were obtained in general accordance with Exported: 06/27/16 ASTMD1557. Arlington, WA Date -03 051 Figure A-3 0482- MOISTURE CONTENT (%) 0 5 10 15 20 25 30 140 135 130 125 (pcf) 120 DRY DENSITY 115 100% Saturation 110 (Gs=2.65) 105 100 Optimum Maximum Depth Moisture Dry Density Symbol Sample (feet) Soil Description (%) (pcf) Corrected 15% 9.1 126.0 N/A 15 Percent Compost/Gravel Borrow Mix Uncorrected Compost 12.5 114.0 Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific Compaction Test Results sample on which they were performed, and should not be interpreted as 15% Compost Mix representative of any other samples obtained at other times, depths or locations,orgenerated by separate operationsorprocesses. Proposed Pole Storage Yard The Proctor results were obtained in general accordance with Exported: 06/30/16 ASTMD1557. Arlington, WA Date -03 051 Figure A-4 0482- MOISTURE CONTENT (%) 0 5 10 15 20 25 125 120 100% 115 Saturation (Gs=2.65) (pcf) 110 DRY DENSITY 105 100 95 Optimum Maximum Depth Moisture Dry Density Symbol Sample (feet) Soil Description (%) (pcf) Corrected 20% 10.6 120.0 Grab Poorly graded sand with gravel and organic matter (SP) Uncorrected Compost 13.7 109.6 Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific Compaction Test Results sample on which they were performed, and should not be interpreted as 20% Compost Mix representative of any other samples obtained at other times, depths or locations,orgenerated by separate operationsorprocesses. Proposed Pole Storage Yard The Proctor results were obtained in general accordance with Exported: 07/08/16 ASTMD1557. Arlington, WA Date -03 051 Figure A-5 0482- Boring #: N/A Sample #: 10% Mix Depth: N/A Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 116.0 Optimum Moisture Content (%) 13.5 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 85.0 Sample Prepared Moisture Content (%) 13.5 Sample length (in): 8.00 (cm): 20.32 (L) Remolded Compaction (%) 85.3 Sample volume (in3): 226.19 (cm3): 3707.33 Sample Back Calculated After Test 86.4 Compaction (%) Sample volume (ft3): 0.1309 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 80.00 81.00 1.00 15.2 50.0 233 1.18E-03 0.066 1.79E-02 22.0 0.9547 1.70E-0224.1 2 80.00 81.00 1.00 15.2 50.0 234 1.17E-03 0.066 1.78E-02 22.0 0.9547 1.70E-0224.0 3 80.00 81.00 1.00 15.2 50.0 232 1.18E-03 0.066 1.80E-02 22.0 0.9547 1.71E-0224.2 4 80.00 81.00 1.00 15.2 50.0 233 1.18E-03 0.066 1.79E-02 22.0 0.9547 1.70E-0224.1 avg 1.79E-02 1.70E-02 24.1 1 80.00 81.00 1.00 15.2 100.0 469 1.17E-03 0.066 1.78E-02 22.0 0.9547 1.69E-02 24.0 2 80.00 81.00 1.00 15.2 100.0 473 1.16E-03 0.066 1.76E-02 22.0 0.9547 1.68E-02 23.8 3 80.00 81.00 1.00 15.2 100.0 473 1.16E-03 0.066 1.76E-02 22.0 0.9547 1.68E-02 23.8 4 80.00 81.00 1.00 15.2 100.0 471 1.16E-03 0.066 1.77E-02 22.0 0.9547 1.69E-02 23.9 5 80.00 81.00 1.00 15.2 100.0 473 1.16E-03 0.066 1.76E-02 22.1 0.9524 1.67E-02 23.7 6 80.00 81.00 1.00 15.2 250.0 1207 1.14E-03 0.066 1.73E-02 22.1 0.9524 1.64E-02 23.2 avg 1.76E-02 1.67E-02 23.7 Total avg 1.77E-02 1.69E-02 23.9 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 10% Compost Mix at 85% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-6 Manual for Western Washington (SWMMWW). Boring #: 10% Compost Sample #: 10% Mix (2) Depth: Grab Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 116.0 Sample area (in2): 28.274 (cm2): 182.43 (A) Optimum Moisture Content (%) 13.5 Target Relative Density (%) 90.0 Sample length (in): 9.00 (cm): 22.86 (L) Sample Prepared Moisture Content (%) 13.5 3 3 Remolded Compaction (%) 90.3 Sample volume (in): 254.47 (cm ): 4170.75 Sample Back Calculated After Test 90 Sample volume (ft3): 0.1473 Compaction (%) Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 79.50 81.80 2.30 15.2 10.0 117 4.69E-04 0.151 3.10E-03 19.4 1.0169 3.14E-034.5 2 79.50 81.80 2.30 15.2 10.0 121 4.53E-04 0.151 2.99E-03 19.4 1.0169 3.04E-034.3 3 79.50 81.80 2.30 15.2 10.0 119 4.61E-04 0.151 3.04E-03 19.4 1.0169 3.09E-034.4 4 79.50 81.80 2.30 15.2 10.0 112 4.89E-04 0.151 3.23E-03 19.4 1.0169 3.28E-034.7 5 79.50 81.80 2.30 15.2 20.0 217 5.05E-04 0.151 3.34E-03 19.4 1.0169 3.39E-034.8 6 79.50 81.80 2.30 15.2 20.0 210 5.22E-04 0.151 3.45E-03 19.5 1.0144 3.49E-035.0 avg 3.19E-03 3.24E-03 4.6 7 79.50 81.80 2.30 15.2 20.0 205 5.35E-04 0.151 3.53E-03 19.5 1.0144 3.58E-035.1 8 79.50 81.80 2.30 15.2 20.0 214 5.12E-04 0.151 3.39E-03 19.5 1.0144 3.43E-034.9 9 79.50 81.80 2.30 15.2 20.0 211 5.20E-04 0.151 3.43E-03 19.5 1.0144 3.48E-034.9 10 79.50 81.80 2.30 15.2 40.0 436 5.03E-04 0.151 3.32E-03 19.4 1.0169 3.37E-034.8 11 79.50 81.80 2.30 15.2 40.0 449 4.88E-04 0.151 3.23E-03 19.4 1.0169 3.28E-034.6 12 79.50 81.80 2.30 15.2 40.0 449 4.88E-04 0.151 3.23E-03 19.4 1.0169 3.28E-034.6 13 79.50 81.80 2.30 15.2 40.0 455 4.82E-04 0.151 3.18E-03 19.4 1.0169 3.23E-034.6 avg 3.33E-03 3.37E-03 4.8 14 79.50 81.80 2.30 15.2 40.0 478 4.59E-04 0.151 3.03E-03 19.3 1.0195 3.08E-034.4 15 79.50 81.80 2.30 15.2 40.0 469 4.68E-04 0.151 3.09E-03 19.2 1.0220 3.15E-034.5 16 79.50 81.80 2.30 15.2 40.0 479 4.58E-04 0.151 3.03E-03 19.2 1.0220 3.09E-034.4 avg 3.05E-03 3.11E-03 4.4 Total avg 3.19E-03 3.24E-03 4.6 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 10% Compost Mix at 90% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-7 Manual for Western Washington (SWMMWW). Constant Head Hydraulic Conductivity Test Project: Arlington Pole Storage Yard Date: 6/28/16 Project #: 0482-051-03 Tested by: S. Swenson Boring #: N/A Sample #: 15% Mix Depth: N/A Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 114.0 Optimum Moisture Content (%) 12.5 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 85.0 Sample Prepared Moisture Content (%) 13.0 Sample length (in): 9.00 (cm): 22.86 (L) Remolded Compaction (%) 84.5 Sample volume (in3): 254.47 (cm3): 4170.75 Sample Back Calculated After Test 91.2 Compaction (%) Sample volume (ft3): 0.1473 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 80.60 81.60 1.00 15.2 10.0 212 2.59E-04 0.066 3.93E-03 20.7 0.9850 3.86E-035.5 2 80.60 81.60 1.00 15.2 10.0 215 2.55E-04 0.066 3.88E-03 20.7 0.9850 3.81E-035.4 3 80.60 81.60 1.00 15.2 10.0 219 2.50E-04 0.066 3.80E-03 20.7 0.9850 3.74E-035.3 4 80.60 81.60 1.00 15.2 10.0 210 2.61E-04 0.066 3.97E-03 20.7 0.9850 3.90E-035.5 5 80.60 81.60 1.00 15.2 10.0 209 2.62E-04 0.066 3.99E-03 20.7 0.9850 3.92E-035.6 6 80.60 81.60 1.00 15.2 10.0 209 2.62E-04 0.066 3.99E-03 21.1 0.9755 3.88E-035.5 7 80.60 81.60 1.00 15.2 10.0 215 2.55E-04 0.066 3.88E-03 21.2 0.9732 3.76E-035.3 avg 3.92E-03 3.84E-03 5.4 1 80.60 81.60 1.00 15.2 20.0 421 2.60E-04 0.066 3.96E-03 21.0 0.9779 3.86E-035.5 2 80.60 81.60 1.00 15.2 20.0 401 2.73E-04 0.066 4.16E-03 20.7 0.9850 4.09E-035.8 3 80.60 81.60 1.00 15.2 20.0 440 2.49E-04 0.066 3.79E-03 20.7 0.9850 3.72E-035.3 4 80.60 81.60 1.00 15.2 20.0 423 2.59E-04 0.066 3.94E-03 21.0 0.9779 3.84E-035.4 avg 3.96E-03 3.88E-03 5.5 Total avg 3.94E-03 3.86E-03 5.5 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 15% Compost Mix at 85% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-8 Manual for Western Washington (SWMMWW). Boring #: Sample #: 15% Mix Depth: Grab Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 114.0 Optimum Moisture Content (%) 12.5 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 90.0 Sample Prepared Moisture Content (%) 12.5 Sample length (in): 9.00 (cm): 22.86 (L) Remolded Compaction (%) 90 Sample volume (in3): 254.47 (cm3): 4170.75 Sample Back Calculated After Test 90.2 Compaction (%) Sample volume (ft3): 0.1473 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 80.20 81.90 1.70 15.2 10.0 393 1.39E-04 0.112 1.25E-03 19.3 1.0195 1.27E-031.8 2 80.20 81.90 1.70 15.2 10.0 408 1.34E-04 0.112 1.20E-03 19.2 1.0220 1.23E-031.7 3 80.20 81.90 1.70 15.2 10.0 393 1.39E-04 0.112 1.25E-03 19.2 1.0220 1.27E-031.8 4 80.20 81.90 1.70 15.2 10.0 374 1.47E-04 0.112 1.31E-03 19.2 1.0220 1.34E-031.9 5 80.20 81.90 1.70 15.2 10.0 382 1.43E-04 0.112 1.28E-03 19.2 1.0220 1.31E-031.9 6 80.20 81.90 1.70 15.2 10.0 380 1.44E-04 0.112 1.29E-03 19.2 1.0220 1.32E-031.9 7 80.20 81.90 1.70 15.2 10.0 374 1.47E-04 0.112 1.31E-03 19.2 1.0220 1.34E-031.9 8 80.20 81.90 1.70 15.2 10.0 372 1.47E-04 0.112 1.32E-03 19.2 1.0220 1.34E-031.9 9 80.20 81.90 1.70 15.2 10.0 377 1.45E-04 0.112 1.30E-03 19.2 1.0220 1.33E-031.9 10 80.20 81.90 1.70 15.2 10.0 367 1.49E-04 0.112 1.34E-03 19.2 1.0220 1.36E-031.9 11 80.20 81.90 1.70 15.2 10.0 369 1.49E-04 0.112 1.33E-03 19.2 1.0220 1.35E-031.9 12 80.20 81.90 1.70 15.2 10.0 371 1.48E-04 0.112 1.32E-03 19.2 1.0220 1.35E-031.9 avg 1.29E-03 1.32E-03 1.9 1 80.20 81.90 1.70 15.2 67.0 2442 1.50E-04 0.112 1.34E-03 21.0 0.9779 1.31E-03 1.9 2 80.20 81.90 1.70 15.2 114.0 4029 1.55E-04 0.112 1.39E-03 20.7 0.9850 1.36E-03 1.9 avg 1.37E-03 1.34E-03 1.9 Total avg 1.33E-03 1.33E-03 1.9 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 15% Compost Mix at 90% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-9 Manual for Western Washington (SWMMWW). Constant Head Permeability Test data Project: Arlington Pole Storage Yard Date: 6/28/16 Project #: 0482-051-03 Tested by: S. Swenson Boring #: N/A Sample #: 20% Mix Depth: N/A Sample dia. (in): 6.00 (cm): 15.24 Max. Dry Density (pcf) 109.6 Optimum Moisture Content (%) 13.7 Sample area (in2): 28.274 (cm2): 182.43 (A) Target Relative Density (%) 85.0 Sample Prepared Moisture Content (%) 13.7 Sample length (in): 9.00 (cm): 22.86 (L) Remolded Compaction (%) 84.7 Sample volume (in3): 254.47 (cm3): 4170.75 Sample Back Calculated After Test 85.4 Compaction (%) Sample volume (ft3): 0.1473 Permeability (k) = LQ/Ad*(h1-h2) Darcy Manometer Manometer Manometer Flowrate Velocity Test H1 H2 Head L Q Time Q/At Gradient k Temp Viscosity k 20Â°C k Number (cm) (cm) (cm) (cm) (cmÂ³) (s) (cm/s) h/L (cm/s) (Â°C) (mPaâ€¢s) (cm/s) (in/hr) 1 79.90 81.90 2.00 15.2 5.0 176 1.56E-04 0.132 1.18E-03 20.8 0.9826 1.16E-03 1.6 2 79.90 81.90 2.00 15.2 5.0 185 1.48E-04 0.132 1.13E-03 20.9 0.9803 1.10E-03 1.6 3 79.90 81.90 2.00 15.2 5.0 158 1.73E-04 0.132 1.32E-03 20.8 0.9826 1.29E-03 1.8 4 79.90 81.90 2.00 15.2 5.0 154 1.78E-04 0.132 1.35E-03 20.9 0.9803 1.32E-03 1.9 5 79.90 81.90 2.00 15.2 5.0 153 1.79E-04 0.132 1.36E-03 20.9 0.9803 1.33E-03 1.9 avg 1.26E-03 1.24E-03 1.8 1 79.90 81.90 2.00 15.2 10.0 350 1.57E-04 0.132 1.19E-03 21.0 0.9779 1.16E-031.6 2 79.90 81.90 2.00 15.2 10.0 337 1.63E-04 0.132 1.24E-03 20.9 0.9803 1.21E-031.7 3 79.90 81.90 2.00 15.2 10.0 338 1.62E-04 0.132 1.23E-03 21.1 0.9755 1.20E-031.7 4 79.90 81.90 2.00 15.2 10.0 342 1.60E-04 0.132 1.22E-03 21.0 0.9779 1.19E-031.7 5 79.90 81.90 2.00 15.2 10.0 340 1.61E-04 0.132 1.23E-03 21.1 0.9755 1.19E-031.7 6 79.90 81.90 2.00 15.2 10.0 335 1.64E-04 0.132 1.24E-03 21.1 0.9755 1.21E-031.7 7 79.90 81.90 2.00 15.2 10.0 337 1.63E-04 0.132 1.24E-03 21.1 0.9755 1.20E-031.7 8 79.90 81.90 2.00 15.2 10.0 341 1.61E-04 0.132 1.22E-03 21.1 0.9755 1.19E-031.7 9 79.90 81.90 2.00 15.2 10.0 336 1.63E-04 0.132 1.24E-03 21.2 0.9732 1.20E-031.7 10 79.90 81.90 2.00 15.2 10.0 339 1.62E-04 0.132 1.23E-03 21.2 0.9732 1.19E-031.7 avg 1.23E-03 1.20E-03 1.7 Total avg 1.25E-03 1.22E-03 1.7 References: Kestin, Sokolov & Wakeham (1978) Saturated Hydraulic Conductivity Test 20% Compost Mix at 85% Compaction Proposed Pole Storage Yard Arlington, Washington Notes: 1. The test was performed following ASTM D 2434 (withdrawn 2015) as modified by Appendix V-B of the 2014 Stormwater Management Figure A-10 Manual for Western Washington (SWMMWW). Appendix D â€“ Well Head Protection Zones Stormwater Site Plan Appendix D Arlington Electrical Equipment &Pole Storage Yard July, 2016 Haller Park Wellfield 4 3 2 1 6 9 10 11 12 7 16 15 14 13 18 Airport Well Project Site 21 22 23 24 19 Area of project site being developed. 28 27 26 25 30 33 34 35 36 31 FIGURE 1 Wells 1-Year-Buffer Wellhead Protection Zone 5-Year 6-Month 5-Year-Buffer WELLHEAD PROTECTION ZONES 6-Month-Buffer 10-Year 1-Year 10-Year-Buffer CITY OF ARLINGTON Feet 0 2,000 Appendix E â€“ Soil Map Stormwater Site Plan Appendix E Arlington Electrical Equipment &Pole Storage Yard July, 2016 Hydrologic Soil Groupâ€”Snohomish County Area, Washington (Arlington Temporary Storage Yard) 122Â° 9' 12'' 122Â° 8' 19'' 563000 563100 563200 563300 563400 563500 563600 563700 563800 563900 564000 48Â° 9' 35'' 48Â° 9' 35'' 5334400 5334400 180th St 59th Dr Bovee Ln 5334300 5334300 Upland Dr 72 5334200 5334200 74 18 5334100 Hillside Ct 5334100 30 39 59th Ave 5334000 5334000 5333900 5333900 67th Ave Highland View Dr 5333800 5333800 5333700 5333700 48Â° 9' 11'' 48Â° 9' 11'' 563000 563100 563200 563300 563400 563500 563600 563700 563800 563900 564000 Map Scale: 1:5,280 if printed on A size (8.5" x 11") sheet. Meters 122Â° 9' 13'' 0 50 100 200 300 122Â° 8' 19'' Feet 0 250 500 1,000 1,500 Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 1 of 4 Hydrologic Soil Groupâ€“Snohomish County Area, Washington (Arlington Temporary Storage Yard) MAP LEGEND MAP INFORMATION Area of Interest (AOI) Map Scale: 1:5,280 if printed on A size (8.5" Ã— 11") sheet. Area of Interest (AOI) The soil surveys that comprise your AOI were mapped at 1:24,000. Soils Soil Map Units Warning: Soil Map may not be valid at this scale. Soil Ratings Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line A placement. The maps do not show the small areas of contrasting A/D soils that could have been shown at a more detailed scale. B Please rely on the bar scale on each map sheet for accurate map B/D measurements. C Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov C/D Coordinate System: UTM Zone 10N NAD83 D This product is generated from the USDA-NRCS certified data as of Not rated or not available the version date(s) listed below. Political Features Soil Survey Area: Snohomish County Area, Washington Cities Survey Area Data: Version 7, Jun 29, 2012 Water Features Date(s) aerial images were photographed: 7/24/2006 Streams and Canals The orthophoto or other base map on which the soil lines were Transportation compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting Rails of map unit boundaries may be evident. Interstate Highways US Routes Major Roads Local Roads Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 2 of 4 Hydrologic Soil Groupâ€“Snohomish County Area, Washington Arlington Temporary Storage Yard Hydrologic Soil Group Hydrologic Soil Groupâ€” Summary by Map Unit â€” Snohomish County Area, Washington (WA661) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 18 Everett gravelly sandy loam, 8 A 5.4 6.8% to 15 percent slopes 30 Lynnwood loamy sand, 0 to 3 A 61.2 76.7% percent slopes 39 Norma loam B/D 12.5 15.7% 72 Tokul gravelly loam, 0 to 8 C 0.3 0.3% percent slopes 74 Tokul gravelly loam, 15 to 25 C 0.3 0.4% percent slopes Totals for Area of Interest 79.8 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Groupâ€“Snohomish County Area, Washington Arlington Temporary Storage Yard Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Natural Resources Web Soil Survey 5/28/2013 Conservation Service National Cooperative Soil Survey Page 4 of 4 Appendix F â€“ Operations and Maintenance Manual Stormwater Site Plan Appendix F Arlington Electrical Equipment &Pole Storage Yard July, 2016 Drip pan NOT TO SCALE Figure IV-2.2.2 Drip Pan Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. Drip pan within rails NOT TO SCALE Figure IV-2.2.3 Drip Pan Within Rails Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.4 Loading Dock with Door Skirt Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.5 Loading Dock with Overhang Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.8 Secondary Containment System Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. Lid NOT TO SCALE Figure IV-2.2.9 Locking System for Drum Lid Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.10 Covered and Bermed Containment Area Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. *Note that the secondary containment is not shown in this figure NOT TO SCALE Figure IV-2.2.11 Mounted Container - with Drip Pan Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.13 Covered Storage Area for Bulk Solids (include berm if needed) D E P A R T M E N T O F Revised December 2015 ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. NOT TO SCALE Figure IV-2.2.14 Material Covered with Plastic Sheeting Revised December 2015 D E P A R T M E N T O F ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. Hydrogeologic Assessment Proposed Pole Yard Arlington, Washington for Snohomish County PUD No. 1 April 26, 2016 Hydrogeologic Assessment Proposed Pole Yard Arlington, Washington for Snohomish County PUD No. 1 April 26, 2016 8410 154th Avenue NE Redmond, Washington 98052 425.861.6000 Table of Contents INTRODUCTION ....................................................................................................................................................... 1 SCOPE OF SERVICES ............................................................................................................................................. 1 SITE DESCRIPTION AND LOCATION ...................................................................................................................... 2 PROPOSED LAND USE ACTIVITES ......................................................................................................................... 2 Pole and Transformer Storage .......................................................................................................................... 3 OVERVIEW OF GEOLOGIC AND HYDROGEOLOGIC CONDITIONS ......................................................................... 3 General Geology ................................................................................................................................................. 3 Hydrogeologic Conditions .................................................................................................................................. 4 Recharge ..................................................................................................................................................... 5 Surface Water Bodies ................................................................................................................................. 5 Water Supplies ............................................................................................................................................ 5 Water Quality ............................................................................................................................................... 5 HYDROGEOLOGIC SITE EVALUATION .................................................................................................................... 6 Soil Texture, Permeability, and Contaminant Attenuation Properties ............................................................ 6 Characteristics of the Unsaturated Soil ............................................................................................................ 6 Depth to Groundwater ....................................................................................................................................... 7 Aquifer Properties .............................................................................................................................................. 8 Potential Impacts to the Aquifer or Groundwater ............................................................................................ 8 Hazardous Materials ................................................................................................................................... 9 CONCLUSIONS AND RECOMMENDATIONS .......................................................................................................... 9 LIMITATIONS ......................................................................................................................................................... 10 REFERNECES ....................................................................................................................................................... 10 LIST OF FIGURES Figure 1. Vicinity Map Figure 2. Site Plan Figure 3. Water Level Data Figure 4. Well Location Map APPENDICES Appendix A. Water Well Reports Figure A-1 â€“ Albert Kluin Sr Well Figure A-2 â€“ Atonement Free Lutheran Well Figure A-3 â€“ Bud Nold Well Figure A-4 â€“ Canus Investment Corp (100 feet deep) Figure A-5 â€“ Canus Investment Corp (217 feet deep) Figure A-6 â€“ City of Arlington, Airport Well Figure A-7 â€“ Elwood R Falor Well Figure A-8 â€“ Gary Bohanon Well Appendix B. Report Limitations and Guidelines for Use April 26, 2016 | Page i File No. 0482-051-03 INTRODUCTION This report presents the results of our hydrogeologic assessment of the proposed Snohomish County Public Utility District No. 1 (Snohomish County PUD) Pole Yard project located between 172nd Street NE and 180th Street NE, east of 59th Avenue NE and west of the Burlington-Northern Santa Fe (BNSF) railroad in Arlington, Washington. The project location is shown on the Vicinity Map, Figure 1. The preliminary layout of the Proposed Pole Yard is shown relative to surrounding physical features on the Site Plan, Figure 2. We previously prepared a draft geotechnical report for the project titled, â€œGeotechnical Engineering Services, Local Office Replacement and Substation, Arlington, Washington,â€ dated May 20, 2013. Additionally, we have been monitoring groundwater levels at the site since February 2013. This report is based on our previous experience at the site and discussions with Snohomish County PUD. We understand that a portion of the site is being developed for a permanent treated-pole and transformer storage area (Pole Yard). Development of this Pole Yard will include constructing gravel laydown areas and asphalt-paved roadways. We understand that the transformer storage area will be paved and curbed, with stormwater captured and routed to an on-site oil stop valve. This hydrogeologic site assessment is provided for the evaluation of the potential groundwater impacts from the proposed Pole Yard on Snohomish PUD property (the site). The City of Arlington (City) requires that a hydrogeologic site assessment be completed for this project because it is located within the 1-year time-of-travel wellhead protection zone associated with a City of Arlington water-supply well, referred to as the Airport Well. The City requires submitting a written assessment that details the hydrogeologic characteristics and subsurface conditions and indicates the susceptibility and potential for contamination of groundwater supplies. The report will be prepared to meet the requirements of a hydrogeologic site assessment per Arlington Municipal Code, Chapter 20.93. SCOPE OF SERVICES Proposed project activities include permanent treated-pole and transformer storage facilities. Our scope of services for this task includes the following: 1. Reviewing available published and site-specific reports and other information regarding the geologic setting, hydrogeology and background water quality of the site and vicinity. 2. Reviewing available well and borehole data within 1,000 feet of the site. 3. Estimating groundwater elevations, recharge potential, flow direction and gradient. Three groundwater monitoring points are needed to estimate the direction of groundwater flow beneath the site. There are two existing groundwater monitoring wells on the site. Access to another well that is completed within the shallow recessional outwash aquifer (less than approximately 50 feet below ground surface) is needed for an accurate flow direction and gradient. 4. Completing a brief site visit to observe geologic conditions, nearby surface water features and springs. 5. Preparing an evaluation of the risk of the hazardous materials to be stored on the facility. If we find that there are potential risks or impacts to critical public aquifer storage recharge areas, we will provide April 26, 2016 | Page 1 File No. 0482-051-03 a discussion of alternatives to avoid or prevent the impacts. We will also describe and list best management practices (BMP) plans. 6. Preparing a hydrogeologic site assessment report by a qualified licensed hydrogeologist. We will submit a draft report to Snohomish County PUD for internal review and comment. After comments are discussed and incorporated, we will produce the final report for submittal to the City. The report will be based on the Cityâ€™s requirements that include descriptions of: ï‚§ Soil texture, permeability, and contaminant attenuation properties; ï‚§ Characteristics of the unsaturated top layer of soil, the vadose zone, and geologic material, including permeability and attenuation properties; ï‚§ Depth to groundwater and/or impermeable soil layer; ï‚§ Aquifer properties such as hydraulic conductivity and gradients; and ï‚§ Potential impacts to the aquifer or groundwater. We received information from Snohomish PUD on the substances used to treat power poles, a preliminary design plan for the Pole Yard, and general descriptions of the proposed facility uses and on-site handling or storage of hazardous materials. Other sources of information are listed in the Bibliography at the end of this report. SITE DESCRIPTION AND LOCATION The site is located approximately 2.8 miles south of the Stillaguamish River within the city limits of Arlington, Washington. Topographically, the site is located within the Marysville Trough, which is a north-south trending lowland that extends from the Stillaguamish River to approximately one mile south of the City of Marysville. The 25.6-acre site is relatively flat, and is currently undeveloped other than a temporary pole storage yard at the western edge of the property. The site grade ranges from about Elevation 140 feet1 in the northeast corner to Elevation 131 feet in the southwest corner. Vegetation on the site consists of recently mowed blackberry brambles, shrubs and scattered deciduous and conifer trees. An abandoned barn is located near the center of the property. The locations of adjacent roads and railroad, the proposed Pole Yard, and locations of boreholes and test pits related to our 2013 geotechnical study are shown on the Site Plan, Figure 2. PROPOSED LAND USE ACTIVITES A Pole Yard operated by Snohomish PUD is proposed for the site. Our understanding of the site activities are based on information provided by Ben Davis, PE of Snohomish PUD. The following activities are proposed: â– Treated power-pole storage 1 Note that all elevations provided in the report are relative to the North American Vertical Datum 1988 (NAVD88). April 26, 2016 | Page 2 File No. 0482-051-03 â– Power transformer storage â– Paved access roads â– Vehicle storage The transformer storage area will be paved and curbed in order to capture and convey stormwater to a treatment area. Within the pole storage area, the existing topsoil will be removed and a layer of soil, specially designed to absorb chemicals that may leach from the treated poles, will be installed. No fueling, fuel storage or vehicle maintenance is proposed at the site. Pole and Transformer Storage Power poles stored at Pole Yard may contain either copper-naphthenate (Cu-Nap), for poles used by Snohomish PUD after 2002, or pentachlorophenol (Penta), for poles used by Snohomish PUD before 2002. Cu-Nap-treated poles will be stored uncovered on-site for short periods of time before they are installed. Penta-treated poles will be temporarily stored uncovered after they have been decommissioned. Approximately four to six times per year, Snohomish PUD operations crews load a 10-yard dump truck with decommissioned poles and haul them off site for disposal. The majority of these poles have been treated with Penta. Rarely, creosote-treated poles are also decommissioned. The Snohomish PUD operations crews may cut Cu-Nap-treated and/or Penta-treated poles on site with a chainsaw in order to fit them into a 10- yard dump truck for disposal. No chipping or treating of poles will occur on Snohomish PUD property. New and decommissioned transformers are to be stored on site within the Pole Yard. New transformers delivered to the site are to be filled off site with mineral oil. There will be no oil-transfer activities on site. Mineral-oil-filled transformers that have been decommissioned and not visibly leaking may be temporarily stored on site. Any decommissioned transformers that are visibly leaking are double-bagged and taken to an off-site disposal facility. No older decommissioned transformers that have the potential to contain polychlorinated biphenyls (PCBs) will be transported to the site. Some vehicles may be stored uncovered elsewhere within the site that may contain potential contaminants, such as oil, diesel, gas and hydraulic fluid. The maintenance of vehicles will be done off site. Visibly leaking vehicles will be removed from the site for service at an off-site location. OVERVIEW OF GEOLOGIC AND HYDROGEOLOGIC CONDITIONS Geologic and hydrogeologic conditions in the vicinity of the site were evaluated by reviewing available published information and the site-specific geotechnical report by GeoEngineers, Inc. (GeoEngineers 2013). The following sections present a general overview of the geologic and hydrogeologic conditions in the site vicinity. General Geology The site is underlain by glacial deposits that were laid down by continental glaciers that advanced into Snohomish County several times during the Pleistocene Epoch (between 2 million and 10,000 years ago). The most recent glaciation period, the Vashon Stade, ended approximately 13,000 years ago. The Vashon Glacier covered the Puget Sound Basin before halting and retreating. After the glaciation period, the Stillaguamish River cut through the glacial deposits and deposited alluvium. The geologic units present in April 26, 2016 | Page 3 File No. 0482-051-03 the project vicinity are, from youngest to oldest: River Alluvium (Qal), Vashon Recessional Outwash (Qvr), Vashon Till (Qvt), Vashon Advance Outwash (Qva), Transitional Beds (Qtb), and Older Gravel (Qog). The following unit descriptions are from Thomas et al. (1997): â– The Qal unit is composed of fluvial deposits from the Stillaguamish River deposited after the glaciation period. Alluvium consists primarily of sand with some gravel, with lenses of fine-grained overbank deposits, gravel and cobbles. The alluvium is typically 40 feet thick near the river. â– The Qvr unit was deposited by the retreating glacier, and covers most of the Marysville Trough. The Qvr is composed of moderately to well-sorted gravel and sand that grades to silt and is typically 40 to 250 feet thick. â– The Qvt unit underlies the Qvr and was deposited by the advancing glacier overriding and reworking older deposits and rocks. Glacial till is compact and typically consists of an unsorted combination of clay- through cobble-sized sediments. The average thickness of Qvt is about 70 feet, but can range from 0 to 250 feet thick. â– The Qva unit underlies the Qvt. The Qva was deposited by meltwater originating from the advancing glacier. The Qva typically has fine-grained sediments that grade upward into coarse-grained deposits. The advance outwash is typically 120 feet thick and up to 350 feet thick. â– The Qtb underlies the Qva. The Qtb is an interglacial unit that was deposited in a low energy environment, consisting of fine-grained materials of sandy to silty clay, with lenses of sand and gravel. The Qtb unit is typically 100 feet thick, up to 400 feet thick. â– The Qog unit underlies the Qtb and is comprised of a wide range of generally coarse-grained sands and gravels. The typical thickness of Qog is about 500 feet, but it can be as thick as 1,000 feet. Hydrogeologic Conditions There are four aquifers in the project vicinity: the Alluvial Aquifer, the Vashon Recessional Aquifer, the Vashon Advance Aquifer and the Deep Aquifer. The Alluvial Aquifer is shallow and is in direct contact with the Stillaguamish River (Pacific Groundwater Group 2007a). The Alluvial Aquifer extends nearly 2 miles south of the present-day location of the Stillaguamish River, but is not present within Â¼-mile of the project site, according to mapping by Minard (1985). The Vashon Recessional Aquifer is an unconfined aquifer that occurs throughout most of the Marysville Trough, including beneath the site. The Vashon Recessional and Vashon Advance Aquifers are hydraulically connected. The transmissivity in the Vashon Recessional Aquifer in the Marysville Trough has a median estimated transmissivity of 15,000 gallons per day per foot (gpd/ft), which may be larger than expected because of a hydraulic connection with the Qva aquifer (Pacific Groundwater Group 2007a). The typical thickness of the Vashon Recessional Aquifer is about 40 feet (Thomas et al. 1997). Water levels in the Vashon Recessional Aquifer vary seasonally and annually between 4 and 19 feet below ground surface (bgs) at the site, based on data recorded during 2013 (GeoEngineers 2013) and subsequently. The Vashon Advance Aquifer is confined or unconfined depending on the presence of Qvt, which acts as a confining unit. In the Marysville Trough, the Qvt is generally eroded, effectively allowing the Qva and Qvr to be hydraulically connected (Pacific Groundwater Group 2007a). In some areas, however, Qvt can be April 26, 2016 | Page 4 File No. 0482-051-03 between 70 and 250 feet thick (Thomas et al. 1997) and can act as a confining unit between the Vashon Recessional and Vashon Advance Aquifers. The Deep Aquifer is confined by the Qtb and has a top elevation from about 100 feet to below â€“400 feet. The median value of transmissivity for the Deep Aquifer is 3,300 gpd/ft (Pacific Groundwater Group 2007a). In the vicinity of the site, the top of the Deep Aquifer is 100 feet bgs, and water levels are at about 102 feet bgs. Recharge Recharge to the aquifers is primarily by infiltration and percolation of precipitation. Average annual recharge to the groundwater by infiltration and percolation is estimated to be approximately 24 inches per year in the vicinity of the City of Arlington (Thomas et al. 1997). According to the same source, the average minimum permeability is 1.3 inches per hour for outwash deposits. The recharge potential for the proposed Pole Yard is high based on the relatively permeable surface and subsurface soils (Thomas et al. 1997). Surface Water Bodies Slightly more than Â¼ mile south of the site is an ephemeral drainage to the Middle Fork Quilceda Creek, which is not a salmon-bearing stream within the nearby reach (DNR 2016). Water Supplies The City of Arlingtonâ€™s water supply is obtained from the Haller Wellfield, the Airport Well, and an intertie between Snohomish PUD and the City of Everett (City of Arlington 2016). The Haller Wellfield is located adjacent to the Stillaguamish River, approximately 3 miles north of the Pole Yard site. The Airport Well is located approximately Â½ mile northwest of the project site. The source of the Airport Well is the Deep Aquifer (Pacific Groundwater Group 2007a). Other water-supply wells exist within the site vicinity; according to Ecology records, there are seven water-supply wells within Â¼ mile of the site boundary. No springs were identified within Â¼ mile from the site. The monitoring wells installed on site by GeoEngineers in 2012 are completed within the Vashon Recessional Aquifer. Water Quality A USGS study conducted in 1992-1993 (Thomas et al. 1997) found the groundwater quality in Snohomish County to be generally good. Water quality was observed to be soft or moderately hard, and dissolved solids concentrations ranged between 36 to 1,040 milligrams per liter (mg/L) with a median of 133 mg/L. The groundwater system had no widespread groundwater contamination, although some contamination was possible because of the presence of agriculture and septic systems. High natural concentrations of iron and manganese, two secondary (aesthetic) contaminants, were common. High iron and manganese have been detected in some water systems near the site, including the Cityâ€™s Arlington Well (Washington Department of Health database 2016). Near Arlington, detectable arsenic was found with concentrations that ranged from less than 1 to 280 micrograms per liter (Âµg/L) and a median of 2 Âµg/L. April 26, 2016 | Page 5 File No. 0482-051-03 HYDROGEOLOGIC SITE EVALUATION The following summary of findings is provided to address the City of Arlingtonâ€™s hydrogeologic site evaluation requirements as listed in Arlington Municipal Code (AMC), Chapter 20.93, Part IX Aquifer Recharge Areas (AMC 20.93.930). A portion of the subject site is located within the 1-year time-of-travel zone of the Airport Well (Pacific Groundwater Group 2007b). Although the Wellhead Protection and Watershed Control Program (RH2 2016) recommends the evaluation of restricting land uses with the 1-year time-of-travel zone through a wellhead protection ordinance, no ordinance currently exists. Soil Texture, Permeability, and Contaminant Attenuation Properties On-site subsurface explorations consisted of six borings (B-1 through B-6) and eight test pits (TP-1 through TP-8) conducted by GeoEngineers (2013). The borings were drilled in 2012 to depths of 26Â½ to 51Â½ feet bgs and the test pits were excavated to depths ranging from 11 to 12 feet below the existing site grade. The approximate locations of the explorations are shown on the Site Plan, Figure 2. Based on the explorations completed at the site, the subsurface conditions generally consist of a thin layer of silty sand overlying recessional outwash (Qvr) deposits. At the surface, we observed 4 to 8 inches of topsoil with roots overlying either fill or native recessional outwash deposits. The topsoil thickness was measured to be 4 inches at four locations and 8 inches in one location across the proposed Pole Yard. A 2-foot thick layer of disturbed native soils was observed in test pits TP-2 through TP-8. A 4-foot-thick layer of disturbed native soils or fill was observed in Boring B-4. The fill or disturbed native soils consist of loose silty sand, with occasional gravel. The fill/disturbed native soils overlie native glacially deposited recessional outwash (Marysville Sand Member) consisting of medium dense to dense sand, with variable silt and gravel content. Recessional outwash soils (Qvr) were observed to the full depth explored. The permeability of the recessional outwash in Snohomish County is conservatively estimated to be 1.3 inches per hour (Thomas et al. 1997). The moderate to high permeability of the soil increases the susceptibility of the underlying aquifer to contamination from the ground surface. However, the concentration of contaminants reaching the water table may be reduced by attenuation processes occurring within the vadose zone. Attenuation processes include biodegradation, dispersion, dilution and sorption and chemical and biological stabilization (EPA 1998). Because the water table in the recessional outwash aquifer is relatively shallow, attenuation of contaminants has a relatively short distance in which to occur before they reach the water table. Biodegradation is the most important attenuation mechanism (EPA 1998), with the organic-material content of the soil affecting contaminant attenuation and transport. The upper layer of the natural soils will be removed from the Pole Yard and replaced by soils specially selected for their attenuation properties beneath permeable areas. The treatment layer will comply with the current (2012) Ecology Stormwater Manual for Western Washington for enhanced treatment. Characteristics of the Unsaturated Soil The surface unsaturated soil is mapped as recessional outwash, which is medium dense to dense sand with variable silt and gravel. A 2- to 4-foot-thick layer of disturbed native soils or fill that consists of loose silty sand with occasional gravel was encountered overlying the recessional outwash. Beneath the surface April 26, 2016 | Page 6 File No. 0482-051-03 layer, at least between 7Â½ and 12 feet of unsaturated recessional outwash was encountered in 2012 (GeoEngineers 2012). The thickness of the unsaturated zone varies with fluctuating groundwater levels, as discussed below. The depth to the bottom of the aquifer was not clearly defined by previous explorations on site. Depth to Groundwater In 2012, groundwater was observed to range from 7 to 12 feet bgs (Elevation 121 to 129 feet). Based on water level data between 2013 and 2016 at the two monitoring wells installed on site in the shallow Vashon Recessional Aquifer, the water levels fluctuate seasonally up to 14 feet and depths range from 4 to 19 feet bgs (Elevation 115 to 131 feet) (Water Level Data, Figure 3). Our review of Washington State Department of Ecology (Ecology) Water Well Reports available on their Well Log Viewer website indicates that there are several records of water-supply wells located within Â¼ mile of the site. Locations of the wells provided on the logs are typically to the nearest quarter-quarter section and are generally considered approximate. According to Ecology records summarized in Table 1 below, there are eight water-supply wells that potentially could be located within a Â¼ mile of the property (Well Location Map, Figure 4). These wells are reportedly drilled to depths ranging from 38 to 217 feet bgs, with water levels ranging from 12 to 217 feet below the top of wells. TABLE 1. SUMMARY OF WATER-SUPPLY WELLS WITHIN THE SITE VICINITY Well Well Water State Plane Coordinates Completion Well Owner Depth Diameter Level Date (feet, bgs) (inches) (feet, bgs) Easting Northing Albert Kluin Sr 38 36 - 05/26/1952 1239205 1032849 Atonement Free 40 6 12 10/12/1987 1240489 1032802 Lutheran Bud Nold 40 6 - 06/21/1989 1240524 1034132 Canus Investment Corp. 217 6 217 10/04/1980 1240563 1035461 Canus Investment Corp. 100 6 12 08/15/1980 1240563 1035461 City of Arlington1 185 10 102 08/1945 1236680 1035611 Elwood R Falor 46 6 - 09/14/1957 1239262 1035509 Gary Bohanon 40 6 - 12/06/1989 1240489 1032802 1 According to the Wellhead Protection Memorandum (Pacific Groundwater Group 2007b), the City of Arlingtonâ€™s Airport Well is located approximately 2,100 feet from the border of the Snohomish PUD site. In addition to these eight water wells, 126 resource protection wells and dewatering wells that range from 12 to 217 feet deep are listed by Ecology within Â¼ mile of the Pole Yard site. The dewatering wells and most of the resource protection wells have likely been decommissioned based on Ecology well log records. Most of the resource protection wells are associated with Welco Lumber. The only known active water supply wells are owned by the Arlington Water Department (Group A), referred to in this report as the Airport April 26, 2016 | Page 7 File No. 0482-051-03 Well, and the Atonement Free Lutheran Church (Group B). Most of these wells do not have accurate locations beyond the typical quarter-quarter section. The Water Well Reports for these wells indicate that groundwater within the Vashon Recessional Aquifer is approximately 10 feet below ground surface. Copies of Water Well Reports for these wells are included in Appendix A. Aquifer Properties Pacific Groundwater Group (2007b) conducted a capture zone study in the vicinity of the City of Arlington, and characterized the three aquifers that are the source of the Cityâ€™s water supply: the Alluvial Aquifer, the Vashon Advance Aquifer, and the Deep Aquifer. The values for primary aquifer parameters determined from their study are presented in Table 2 below. The flow direction for the Deep Aquifer near the site is to the northwest towards the Stillaguamish River. The unconfined Vashon Recessional Aquifer beneath the site likely has a similar flow direction as the Deep Aquifer. TABLE 2. AQUIFER PARAMETERS Hydraulic Conductivity Hydraulic Gradient Effective Porosity Name K i ne (feet per day) (feet per foot) (ftÂ³/ftÂ³) Alluvial Aquifer 3,119 0.002 0.27 Vashon Recessional 180 0.011 0.27 Aquifer Vashon Advance Aquifer 40 0.016 0.27 Deep Aquifer 134 0.05 0.27 Notes: Data from Pacific Groundwater Group (2007b) We were not able to access a third well completed in the shallow Vashon Recessional Aquifer. Therefore, a site-specific hydraulic gradient and flow direction were not obtained. However, the on-site monitoring wells B-3 and B-4 are approximately 935 feet apart and the water elevation from B-3 was 5.2 feet lower than the water elevation in B-4 on February 9, 2016, consistent with a northwest flowing aquifer. The water levels in the two wells indicate a two-dimensional gradient of 0.005 feet per foot. Based on this estimated gradient and depth to groundwater measurements, we anticipate that groundwater levels below the proposed Pole Yard will be greater than 5 feet below existing grade. Potential Impacts to the Aquifer or Groundwater Because of the high permeability of the recessional outwash and the shallow depth to groundwater, the site is susceptible to shallow groundwater contamination. The source aquifer for the Airport Well is the Deep Aquifer encountered at a depth of 112 feet bgs. In order for contamination to reach the Deep Aquifer it would have to travel down through the unconfined shallow Vashon Recessional Aquifer and through a confining layer that is 9-foot-thick and consists of fine sand and clay at the well location. The confining unit therefore provides protection from contaminants potentially released at the surface. April 26, 2016 | Page 8 File No. 0482-051-03 Hazardous Materials Snohomish PUD no longer uses Penta- or creosote-treated wood poles. These products are being phased out of use as old poles are replaced with newer ones. The use of Penta and creosote to treat and preserve wood poles has been replaced by Cu-Nap. Cu-Nap is a non-restricted oil-borne wood preservative used to protect wood from decay by microorganisms and wood-eating insects. Cu-Nap concentrate is classified as a â€œgeneral useâ€ pesticide by the United States Environmental Protection Agency (EPA) under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). It has been standardized for use by the American Wood Protection Association (AWPA) (EPA Reg. No. 71992-1-54471). General use pesticides are those that are not classified by EPA for restricted use (40 CFR 152.175). The FIFRA requires that all pesticides sold or distributed in the United States be registered by the EPA. Registration is based on evaluation of scientific data and assessment of risks and benefits of a product's use. Cu-Nap-treated poles will be stored at the site according to all applicable regulations. There will be no storage or application of concentrated Cu-Nap or Penta or PCBs at the site (personal communication Ben Davis, Snohomish PUD, March 15, 2016). Equipment (vehicles or transformers) will be inspected for leaks prior to being stored at the site. Any leaking equipment will be assessed and taken to an off-site facility. CONCLUSIONS AND RECOMMENDATIONS The water-table aquifer beneath the site is shallow and is potentially susceptible to water quality impacts due to the highly permeable nature of the surface soils. However, the deeper regional aquifer that is a source for the City of Arlingtonâ€™s Airport Well, located more than 2,000 feet from the site, is likely protected by the presence of one or more fine-grained layers that form aquitards, or confining units, beneath the site, and would limit or delay contamination from reaching the deep aquifer. Furthermore, steps are planned at the site that will reduce the likelihood of the potential contaminants such as hydrocarbons, mineral oil and Cu-Nap from reaching the groundwater table. Because of the activities proposed on the site and its location within the 1-year time-of-travel wellhead protection zone of the Cityâ€™s Airport Well, we recommend the following: 1. Incorporate Best Management Practices (BMPs) that conform to Ecologyâ€™s Stormwater Management Manual for Western Washington. 2. Infiltration facilities, if proposed, should meet BMPs to protect groundwater quality. 3. Store the transformers only in a paved area designated for that purpose. 4. Capture and convey stormwater that occurs within the transformer storage area to an on-site treatment area. 5. Add a layer of soil beneath permeable sections that has improved contaminant attenuation properties. 6. Require that an approved Spill Prevention and Control Plan be prepared before the facility is actively used that identifies equipment and structures that could fail, resulting in an impact to the underlying aquifer. Spill plans shall include provisions for regular inspection, repair, and replacement of structures and equipment with the potential to fail. April 26, 2016 | Page 9 File No. 0482-051-03 In our opinion, the proposed development will likely cause little or no adverse impact to the quality of water in the shallow aquifer beneath the site if the above-mentioned recommendations are implemented, including infiltration of stormwater with sufficient treatment BMPs for the transformer storage area. The occurrence of 9 feet of unsaturated soil and a confining layer beneath the shallow aquifer will provide added protection against impacts to the deep aquifer that is the source of the City of Arlingtonâ€™s water supply. LIMITATIONS We have prepared this report for use by Snohomish County PUD No. 1 for the proposed Local Office Replacement and Substation located between 172nd Street NE and 180th Street NE off of 59th Avenue NE in Arlington, Washington. Our services were provided to complete a hydrogeologic assessment related to permitting for planned facilities and activities to be located on the property. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of hydrogeology in this area at the time this report was prepared. No warranty or other conditions, express or implied, should be understood. Please refer to Appendix B titled â€œReport Limitations and Guidelines for Useâ€ for additional information pertaining to use of this report. REFERNECES City of Arlington, 2016, 2015 Comprehensive Water System Plan. Final. Released January 2016. Prepared with assistance from RH2 Engineering Inc. and FCS Group Inc. GeoEngineers, Inc., May 20, 2013, Geotechnical Engineering Services, Local Office Replacement and Substation, Arlington, Washington. Prepared for Snohomish County PUD No. 1. File No. 0482-051-01. Snohomish County Planning and Development Services, GIS-Cartography Section. 2007. Aquifer Recharge/Wellhead Protection Map. Revised October 1, 2007. Available at http://snohomishcountywa.gov/DocumentCenter/View/8240 Thomas, B.E., Wilkinson, J.M., and Embrey, S.S. 1997. The Ground-Water System and Ground-Water Quality in Western Snohomish County, Washington. US Geological Survey Water-Resources Investigations Report 86-4312. Washington State Department of Natural Resources (DNR). 2016. Forest Practices Application Mapping Tool. Accessed on 30 March 2016. Available at https://fortress.wa.gov/dnr/protectiongis/fpamt/index.html# Minard, J.P., 1985, Geologic Maps of the Arlington West 7.5 Minute Quadrangle, Snohomish County, Washington. United States Geological Survey. Miscellaneous Field Studies Map MP-1740. Available at http://ngmdb.usgs.gov/Prodesc/proddesc_7432.htm Pacific Groundwater Group, January 2007a, Hydrogeologic Conceptual Model Summary Report. City of Arlington. April 26, 2016 | Page 10 File No. 0482-051-03 Pacific Groundwater Group. February 4, 2007b, Wellhead Protection Capture Zone Delineation Memorandum. City of Arlington. Snohomish County Planning and Development Services, GIS-Cartography Section, 2007, Aquifer Recharge/Wellhead Protection Map. Revised October 1, 2007. Available at http://snohomishcountywa.gov/DocumentCenter/View/8240 Thomas, B.E., Wilkinson, J.M., and Embrey, S.S., 1997, The Ground-Water System and Ground-Water Quality in Western Snohomish County, Washington. US Geological Survey Water-Resources Investigations Report 86-4312. U.S. Environmental Protection Agency, 1998, Technical Protocol for Evaluation Natural Attenuation of Chlorinated Solvents in Ground Water (Appendix A), U.S. EPA, Office of Research and Development, EPA./600/R-98/128. Washington State Department of Health, 2016, Sentry Internet. Division of Environmental Health, Office of Drinking Water. Available at https://fortress.wa.gov/doh/eh/portal/odw/si/Intro.aspx April 26, 2016 | Page 11 File No. 0482-051-03 FIGURES UV9 Olympic Pl NE Portage St Burn Rd 206Th St NE PP oo Old Burn Rd 204Th St NE rr Lois Ln t t a ouutthhPPoorrttaa 64Th Dr NE 69Th Ave NE agg SSo gg e ee C CC C r 43Rd Ave NE rreeee re k e e 71St Ave NE e k 200Th St NE 62Nd Dr NE k Cemetery Rd 199Th St NE PP Knoll Dr r r a a i ir r i 196Th Pl NE 62Nd Ave NE iee Smokey Point Blvd CCrree ee Vista Dr Crown Ridge Blvd kk 192Nd Pl NE 23Rd Ave NE 68Th Dr NE 47Th Ave NE 63Rd Ave NE 191St Pl NE 190Th Pl NE 59Th Dr NE 188Th St NE 188Th St NE 23Rd Ave NE 188Th St NE 66Th Ave NE Champions Dr Greywalls Dr Service Rd 35Th Ave NE 184Th St NE Harrow Pl Eaglefield Dr 59Th Ave NE Oxford Dr 31St Dr NE 180Th St NE 178Th Pl NE 176Th Pl NE Arlington Muni Ironwood St 174Th Pl NE Stillaguamish Hwy 43Rd Ave NE Highland View Dr 19Th Ave NE 25Th Ave NE SITE Redhawk Dr 19Th Dr NE 531 79Th Ave NE 169Th Pl NE 27Th Ave NE Twin Lakes Ave 27Th Ave NE 168Th St NE 168Th St NE 79Th Ave NE 71St Dr NE Map Revised: 17 August 2012 syi Mcpherson Rd 25Th Ave NE 165Th Pl NE kk 162Nd Pl NE ee ee rr CC aa 162Nd St NE dd ee cc ll i Gissberg Twin LakesPacific Hwy uiu 51St Ave NE QQ rkrk o 19Th Ave NE F F 156Th St NE lele 156Th St NE d didi 73Rd Ave NE M 77Th Ave NE Â§Â¨Â¦ 152Nd St NE 81St Ave NE 5 18Th Dr NE45Th Rd 147Th Pl NE 23Rd Ave NE 40Th Ave NE 67Th Ave NE 145Th St NE ddaa CCrreeekk QQuilccee 143Rd Pl NE Nina Lake W a s h i n g t o n Â§Â¨Â¦405 Âµ Â§Â¨Â¦90 2,000 0 2,000 Â§Â¨Â¦5 I d a h o Â§Â¨Â¦84 Feet O r e g o n Notes: Vicinity Map 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. can not guarantee the accuracy and content of electronic files. The master Proposed Pole Yard file is stored by GeoEngineers, Inc. and will serve as the official record of Arlington, Washington this communication. 3. It is unlawful to copy or reproduce all or any part thereof, whether for personal use or resale, without permission. Data Sources: ESRI Data & Maps Figure 1 Projection: NAD 1983 UTM Zone 10N Office: SEA Path: W:\Seattle\Projects\0\0482051\01\GIS\MXD\048205101_VicinityMap.mxd PROPOSED POLE YARD X X 136 B-1 137 137 X 135 X 142 3013 DEA_CON 135 10428 10427136.19 136.11TOE X TOE 10426 136.05 TOE137 10429 136.21 TOE 10425 136.14 X TOE 10430 136.18 TP-6 TOE 136 SCY X 140 : X 138 3012 X 137.24 DEA_CON X REDM:BDR X 133 136 3011 TP-4 134.49 X DEA_CON 132 133 133 134 TP-1 135 133 X X X 135 TP-3 TP-7 3010 134.56 132 DEA_CON B-5 136 135 135 B-3 136 136 3009 135.31 B-2 DEA_CON 132 TP-5 TP-2 TP-8 B-6 131 3008 131.92 132 DEA_CON 133 132 132 131 133 B-4 SITE BOUNDARY Notes: Legend N Site Plan 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in W E B-1 Approximate boring location showing features discussed in an attached document. Proposed Pole Yard GeoEngineers, Inc. cannot guarantee the accuracy and content S Arlington, Washington B-3 Approximate boring/groundwater monitoring well location 200 0 200 of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. TP-1 Approximate test pit location Feet Figure 2 Reference: Snohomish County PUD No. 1. P:\0\0482051\CAD\03\T100 Geotech\048205103_T100_F2.dwg\TAB:F2 modified on Mar 28, 2016 - 11:55am 0 3.0 Precipitation B-3 Pressure Transducer Data B-3 Manual Water Readings B-4 Pressure Transducer Data 2.8 B-4 Manual Water Readings 2.6 5 2.4 2.2 2.0 10 1.8 1.6 1.4 15 1.2 1.0 0.8 20 0.6 0.4 0.2 Daily Precipitation (inches) 25 0.0 Water Level (Feet Below Ground Surface) 6/1/2012 8/1/2012 2/1/2013 4/1/2013 6/1/2013 8/1/2013 2/1/2014 4/1/2014 6/1/2014 8/1/2014 2/1/2015 4/1/2015 6/1/2015 8/1/2015 2/1/2016 4/1/2016 10/1/2012 12/1/2012 10/1/2013 12/1/2013 10/1/2014 12/1/2014 10/1/2015 12/1/2015 Water Level Data Notes: 1. Precipitation Data from NOAA Land Based Station Lake Stevens 0.9 Proposed Pole Yard NW WA US GHCND:US1WASN0074 2. Ground surface elevation for B-3 is approximately 134 feet (NAVD88) Arlington, Washington 3. Ground surface elevation for B-4 is approximately 134.5 feet (NAVD88) Figure 3 59th Ave NE CITY OF 67th Ave NE ARLINGTON ELWOOD CANUS R FALOR ï‚¡@< INVESTMENT ï‚¡@< CORP.ï‚¡@< BUD NOLD ï‚¡@< ATONEMENT ALBERT FREE 59th Ave NE KLUIN SR LUTHERAN ï‚¡@< GARY BOHANONï‚¡@< SR 531 SR 531 172nd St NE SR 531 NE MiddleFork Quilceda Creek 67th Ave NE Legend Site Boundary 1,000 0 1,000 0.25 mile Buffer Tax Parcel Boundary Feet Âµ Notes: 1. The locations of all features shown are approximate. Well Locations are approximate and may only be accurate to Well Location Map a quarter-quarter section. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the Proposed Pole Yard accuracy and content of electronic files. The master file Arlington, Washington is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Data Source: Figure 4 Projection: NAD 1983 StatePlane Washington North FIPS 4601 Feet P:\0\0482051\GIS\MXD\048205101_WellLocations.mxd Date Exported: 04/26/16 by maugust APPENDICES APPENDIX A Water Well Reports APPENDIX B Report Limitations and Guidelines for Use APPENDIX B REPORT LIMITATIONS AND GUIDELINES FOR USE2 This appendix provides information to help you manage your risks with respect to the use of this report. Hydrogeologic Services are Performed for Specific Purposes, Persons and Projects This report has been prepared for the exclusive use of Snohomish County Public Utilities District No. 1. This report is not intended for use by others, and the information contained herein is not applicable to other sites. GeoEngineers structures our services to meet the specific needs of our clients. For example, a hydrogeologic study conducted for a civil engineer or architect may not fulfill the needs of a construction contractor or even another civil engineer or architect that are involved in the same project. Because each hydrogeologic study is unique, each hydrogeologic report is unique, prepared solely for the specific client and project site. Our report is prepared for the exclusive use of Snohomish County Public Utilities District No. 1. No other party may rely on the product of our services unless we agree in advance to such reliance in writing. This is to provide our firm with reasonable protection against open-ended liability claims by third parties with whom there would otherwise be no contractual limits to their actions. Within the limitations of scope, schedule and budget, our services have been executed in accordance with our Agreement with Tacoma Public Utilities and generally accepted geotechnical practices in this area at the time this report was prepared. This report should not be applied for any purpose or project except the one originally contemplated. A Hydrogeologic Report is Based on a Unique Set of Project-Specific Factors This report has been prepared for the proposed Pole Yard site in Arlington, Washington. GeoEngineers considered a number of unique, project-specific factors when establishing the scope of services for this project and report. Unless GeoEngineers specifically indicates otherwise, do not rely on this report if it was: â– not prepared for you, â– not prepared for your project, â– not prepared for the specific site explored, or â– completed before important project changes were made. For example, changes that can affect the applicability of this report include those that affect: â– the function of the proposed structure; â– elevation, configuration, location, orientation or weight of the proposed structure; â– composition of the design team; or â– project ownership. 2 Developed based on material provided by ASFE, Professional Firms Practicing in the Geosciences; www.asfe.org. April 26, 2016 | Page B-1 File No. 0482-051-03 If important changes are made after the date of this report, GeoEngineers should be given the opportunity to review our interpretations and recommendations and provide written modifications or confirmation, as appropriate. Subsurface Conditions Can Change This hydrogeologic report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by manmade events such as construction on or adjacent to the site, or by natural events such as floods, earthquakes, slope instability or ground water fluctuations. Always contact GeoEngineers before applying a report to determine if it remains applicable. Topsoil For the purposes of this report, we consider topsoil to consist of generally fine-grained soil with an appreciable amount of organic matter based on visual examination, and to be unsuitable for direct support of the proposed improvements. However, the organic content and other mineralogical and gradational characteristics used to evaluate the suitability of soil for use in landscaping and agricultural purposes was not determined, nor considered in our analyses. Therefore, the information and recommendations in this report, and our logs and descriptions should not be used as a basis for estimating the volume of topsoil available for such purposes. Most Hydrogeologic Findings Are Professional Opinions Our interpretations of subsurface conditions are based on field observations from widely spaced sampling locations at the site. Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field and published data and then applied our professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ, sometimes significantly, from those indicated in this report. Our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. Read These Provisions Closely Some clients, design professionals and contractors may not recognize that the geoscience practices (hydrogeology or geology) are far less exact than other engineering and natural science disciplines. This lack of understanding can create unrealistic expectations that could lead to disappointments, claims and disputes. GeoEngineers includes these explanatory â€œlimitationsâ€ provisions in our reports to help reduce such risks. Please confer with GeoEngineers if you are unclear how these â€œReport Limitations and Guidelines for Useâ€ apply to your project or site. Hydrogeologic, Geotechnical, Geologic and Environmental Reports Should not be Interchanged The equipment, techniques and personnel used to perform an environmental study differ significantly from those used to perform a hydrogeologic, geotechnical or geologic study and vice versa. For that reason, a geotechnical engineering or geologic report does not usually relate any environmental findings, conclusions or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Similarly, environmental reports are not used to address geotechnical or geologic concerns regarding a specific project. April 26, 2016 | Page B-2 File No. 0482-051-03 Biological Pollutants GeoEngineersâ€™ Scope of Work specifically excludes the investigation, detection, prevention, or assessment of the presence of Biological Pollutants in or around any structure. Accordingly, this report includes no interpretations, recommendations, findings, or conclusions for the purpose of detecting, preventing, assessing, or abating Biological Pollutants. The term â€œBiological Pollutantsâ€ includes, but is not limited to, molds, fungi, spores, bacteria, and viruses, and/or any of their byproducts. April 26, 2016 | Page B-3 File No. 0482-051-03 Have we delivered World Class Client Service? Please let us know by visiting www.geoengineers.com/feedback. Plaza 600 Building 600 Stewart Street, Suite 1700 Seattle, Washington 98101 206.728.6274 June 28, 2016 Snohomish County PUD No. 1 Facilities Department 2320 California Street Everett, Washington 98201 Attention: Ben Davis, PE Subject: Response Letter Wetlands/Streams Proposed Arlington Local Office Replacement and Substation Arlington, Washington File No. 0482-051-03 GeoEngineers, Inc. (GeoEngineers) understands that the project site (Figure 1) located near 180th Street NE and 59th Avenue NE in Arlington, Washington is being developed for a new local office building, access roadways, solar arrays, substation, and a pole and transformer storage area for the Snohomish County PUD No. 1 (SnoPUD). The site is located immediately east of the Arlington Municipal Airport. Development of the pole and transformer storage area will include constructing gravel laydown areas, asphalt paved roadways, and installation of a waterline. GeoEngineers further understands that design of the local office building, other roadways, solar arrays, and the substation will occur at a later date. SnoPUD requested that GeoEngineers complete a wetland reconnaissance of the site to provide our opinion related to wetlands that may be located on the project site. Following your request, GeoEngineersâ€™ Professional Wetland Scientist (PWS), performed a reconnaissance of the site on March 16, 2016. The PWS accessed the site via the man-gate along the southern property line and conducted a pedestrian survey of the property. General site observations of the approximate 26-acre parcel verified that the project site is Photo 1. Representative condition of the site, May 10, 2016. Snohomish County PUD No. 1 | June 28, 2016 Page 2 undeveloped and relatively flat uplands with no structures except for an abandoned barn located near the north-central portion of the project site (Photo 1). The parcel is predominantly vegetated with mowed grasses, forbs and Scotch broom (Cytisus scoparius); as well as, trees including big leaf maple (Acer macrophyllum), Douglas fir (Pseudotsuga menziesii) and ornamental apple (Malus spp.) which are indicative of uplands. While on site, GeoEngineersâ€™ PWS looked for wetland indicators such as changes in vegetation type, depressional areas and the presence of surface water. However, no wetlands were observed on the site during the pedestrian survey. Precipitation data collected at the Arlington Airport (Weather Underground, 2016) indicates 0.77 inches of rain near the site in the week preceding our March site visit. There was no surface water observed on site; however, a ditch was observed immediately east of the site and adjacent to the Burlington Northernâ€“ Santa Fe (BNSF) railroad line. Presumably this ditch is owned and maintained by BNSF. The average wetted width of the ditch was approximately 4 to 5 feet wide and appeared to be flowing slowly south at approximately 0.5 foot per second. Average depth of the wetted channel was approximately 12 inches. The east bank of the ditch has no vegetation and is covered in rail ballast extending into the ditch (Photo 2). The west bank of the channel is fully vegetated and covered with willows (Salix spp.), Himalayan blackberry (Rubus armeniacus), red alder (Alnus rubra) and cottonwood (Populus balsamifera) trees. No fish were observed in the ditch by the PWS. Following the March 16 site visit, the GeoEngineers PWS reviewed available public data regarding the ditch observed along the eastern boundary of the site. The Washington State Department of Fish and Wildlife (WDFW, 2016a), the Washington State Department of Natural Resources (WDNR, 2016) and Snohomish County (2016) do not map streams or waterways within the project boundary. WDFW (2016b) maps an â€œintermittent/ephemeralâ€ water course traversing the site from the northeast corner to the south-central portion of the site prior to leaving the property. We did not observe features at the site as mapped by WDFW (2016b). Based on our observations and data obtained from other sources, we believe that there are substantial errors in the WDFW (2016b) mapping data. The City of Arlington Stormwater Infrastructure Map (2016a) indicates the ditch along the eastern edge of the site conveys flows from a series of stormwater ponds located approximately 2,500 feet north of the site, near the intersection of 67th Ave NE and Woodlands Way. These stormwater ponds collect runoff from a larger residential development located southeast of the ponds. According to the City of Arlington (2016), the ditch flows south along the BNSF railway, past the eastern edge of the site and is eventually collected within the closed stormwater system of the developed area located south of the site. File No. 0482-051-03 Snohomish County PUD No. 1 | June 28, 2016 Page 3 The GeoEngineers PWS returned to the site on May 10, 2016 to verify public data and investigate the hydrology of the ditch. Precipitation data collected at the Arlington Airport (Weather Underground, 2016) indicates very little rain (0.02 inches) in the week prior to the May site visit. The ditch (Photo 2) was completely dry with vegetation establishing in the bed of the channel. We observed indications of recent inundation but it appears that this ditch experiences intermittent flow. This ditch is likely inundated during the winter when shallow groundwater is elevated and surface runoff is high. However, the ditch is not expected to flow perennially. As mapped by the City of Arlington (2016a), we observed less than 0.5 cubic feet per second (cfs) of flow from the stormwater ponds located 2,500 feet north of the site into a closed conveyance in the 67th Avenue NE right-of-way. Because of private property access issues, the PWS was not able to observe the mapped outfall of this stormwater system into the ditch adjacent to the BNSF railway. Most likely, the ditch adjacent to the BNSF railway conveys flow from the stormwater system located north of the site. According to Marc Hayes, City of Arlington Manager of Community and Economic Development (2016), smaller volumes, such as the 0.5 cfs observed Photo 2. Ditch adjacent to site, May 10, 2016. entering the stormwater system on May 10, 2016, likely infiltrate into the sandy substrate of the nearly level ditch prior to flowing past the site. We expect the ditch to be inundated only after periods of rain and runoff from the developed areas east of the site. It is our opinion that this ditch primarily functions as a stormwater conveyance and infiltration feature. We observed inundation in the ditch approximately 450 feet south of the site. At this location we observed water flowing into the ditch from a 24-inch round concrete pipe culvert that conveys flow under the BNSF railway from the area east of the railway. The City of Arlington (2016a) identifies the area east of the BNSF railway as constructed stormwater feature. Based on our observations, available map data and professional experience on similar sites, it is GeoEngineersâ€™ opinion that wetlands and stream features, regulated under City of Arlington Code Chapter 20.88.700 and 28.88.800 are not located within or adjacent to the site. REFERENCES City of Arlington. 2016a. Stormwater Inventory Map, dated April 15, 2015. http://www.arlingtonwa.gov/modules/showdocument.aspx?documentid=6637 Accessed May 2016. City of Arlington. 2016b. Personal communication between Marc Hayes (City of Arlington Manager of Community and Economic Development) and Ben Davis (SnoPUD). May 13, 2016. File No. 0482-051-03 Stormwater Stormwater Pond Pond Project Site Ditch Stormwater Pond Legend Approximate Site Boundary Not to Scale Site Map Notes: Arlington Office Replacement/Substation 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing Arlington, Washington features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Figure 1 Data Source: U.S. Fish and Wildlife Service National Wetland Inventory Map 00482-051-03 Date Exported: 04/26/16 WATER UTILITY BILL OF SALE AND WARRANTY Community & Economic Development City of Arlington 18204 59th Avenue NE â€¢ Arlington, WA 98223 â€¢ Phone (360] 403 3551 (Items that will be dedicated to the City of Arlington and will become part of the Public Utility System) Know all men by these presents, Public Utility District No. 1, does hereby grant, bargain, sell and convey, for a valuable consideration, unto the City of Arlington, Washington, a municipal corporation, all of that certain water pipe and appurtenances, situated and described below: QUANTITY SIZE DESCRIPTION CONSTRUCTION COST 1.004| Lf. 12 inch Ductile Iron $ 88352.00 89] l.f. 8 inch Ductile Iron $ 6,675.00 Lf. inch Ductile Iron $ Lf. inch Ductile Iron $ 11 ea. Fire Hydrant Assembly $ 5,000.00 ea. Blow Off Assembly $ ea. Pressure Reducing Valve $ - ea. inch Casing $ ea. inch Services[s) $ - ea. inch Services[s) $ - ea. inch Services[s] $ .._,._!_ Other* $ Total $ 100,027.00 *Not Required: Items outside the City's right of way or utility easements. in the Plat or development of the PUD Electrical Equipment and Pole Yard and more particularly in easements, streets, and public right-of-ways as described and as shown on an as-built drawing of said installation, attached hereto and made a part of this document The grantor represents and warrants to the City of Arlington that all of the expenses in connection with construction and installation of said pipe line and appurtenances have been full paid and the same is free from liens and debts; the grantor agrees to indemnify and hold the City harmless from any lawful claims of any party for labor or materials arising out of construction and installation of said line and appurtenances. The grantor warrants to the City that said line and appurtenances were constructed and installed in accordance with City standards and specifications. The grantor warrants the labor and materials used in said construction and installation for a period of two years from the date of maintenance bond acceptance by the City; further, the grantor agrees to indemnify and hold the City harmless from any and all claims for damages arising from defective materials or workmanship for a period of two years from the date of maintenance bond acceptance by the City. ACCEPTED BY CITY OF ARLINGTON Signature: ^ Signature: Print Name^ rt^^i.g^^EjJ L.. ^ftfZ^/CS. Print Name: LAUNAPETERSON Title: rt^/uA/^2. /^L eSTTTTf ^gSmc^Title PERMIT TECHNICIAN H This record was acknowledged before me on ? 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