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7530 204th St Ne_PWD3732- Submittal and Review Docs_2026
i CONSTRUCTION PERMIT APPLICATION Community&Economic Development City of Arlington • 18204 59th Avenue NE • Arlington,WA 98223 • Phone(360) 403-3551 CIVIL(TYPE I) GRADING/PAVING/DRAINAGE(TYPE II) RIGHT OF WAY(TYPE III) TYPE I&II ONLY NEW DEVELOPMENT REDEVELOPMENT Project Name:Wet Rabbit Express Car Wash Snohomish County Tax Parcel I.D.#: 310514000100600, 310514000101000 Project Address/Location:7530 20th St SE Description of Project:Construction of an automated conveyor type car wash (+/- 5,000 sf tunnel) OWNER Name: Charles Chaffee Address: 23594 13th Ave NE city: Arlington State:WA zip:98223 Phone: Email: APPLICANT Name:Chris McClure Address:3213 W. Wheeler St. #750 city:Seattle State:WA zi :98199 Phone:(206) 284-8200 Email: chris@wetrabbitexpress.com ENGINEER Name: Travis Cheshire, P.E. (PACLAND - Seattle) Address: 6814 Greenwood Ave N City: Seattle State:WA Zip: 98103 Phone: (206) 212-0608 Email:theshire@pacland.com License#:23031991 Expiration:0 1/29/2025 CONTRACTOR Name:TBD Address: City: State: Zip: Phone: Email: License#: Expiration: 1, hereby certify that I have read and examined this application, City of Arlington Municipal Code, Standard Plan & Specifications. Performance of the proposed work shall follow all applicable laws and regulations.The owner/applicant shall assume full and complete responsibility for said work and shall be responsible for the acquisition and compliance of all applicable permits and/or authorizations which may include, but not limited to, Right of Way Permit,WSDW Hydraulic Project Approval(HPA),WSDOE Notice of Intent(NOI),National Pollutant Discharge Elimination System(NPDES),Army Corp.of Engineers Perm' ps,,�th&�re, ments of the Endangered Species Act,and the Forest Practices Application(FPA). Signature , Print Name: Chris McClure Date:4/3/24 Pagel of 2 REV11/2021 Complete package constitutes all items. Only complete submittals will be accepted. Civil-Submittal Requirements,Type I: Electronic files shall be PDF on USB flash-drive,email,or drop-box ❑ Complete Application ❑ Construction Plans including cut/fill quantities ■ 2 full size plan sets 22"x 34" ■ PDF file of the complete plan set ■ 2 full size set of landscape plans 22"x 34" ❑ Marysville Utility plans,if applicable(2 sets) ❑ Drainage Analysis including calculations and downstream analysis (2 sets)and(PDF file); refer to Stormwater Drainage Requirements ❑ Geotechnical Report(2 sets)and(PDF file) ❑ SEPA is required if 500 or more cubic yards of cut/fill is proposed(not required if included with a Land Use Permit);if there is not a Land Use Permit associated with the project,Public Notice Materials will be required ❑ Grading cut/fill quantity: net --: 74 cy (imp0rt) ❑ Design Vehicle-demonstrate turning radius include 45'Fire truck,dual axle,256-inch wheelbase ❑ Drafts of easement(s)dedication(s),and/or CAPE(s)for review ❑ Flood Hazard Permit Application and required documentation if project is within 100-year flood plain;refer to Flood Hazard guidance documents ❑ Construction Calculation Worksheet ❑ NPDES Permit(if required);See Storm Water Drainage Report,New or Redevelopment Flowcharts ❑ Assurance Device will be required prior to Permit Issuance(Bond or Assignment of Funds) ❑ Permit Fee due at time of permit submittal Grading Paving Drainage Submittal Requirements,Type II:Electronic filesshall be PDF on USB flash-drive,email,or drop-box ❑ Complete Application ❑ Construction Plans including import/export quantities ■ 2 full size plan sets 22"x 34" ■ PDF file of the complete plan set ❑ Drainage Analysis including calculations and downstream analysis(2 sets)and (PDF file);refer to Stormwater Drainage Requirements ❑ Geotechnical Report(2 sets)and(PDF file) ❑ SEPA is required if 500 or more cubic yards of cut/fill is proposed(not required if included with a Land Use Permit) ❑ SEPA Public Notice Material Requirements: ■ Snohomish County Assessor's Quarter Section Map: ❑ Show Subject Property ❑ Show 500 ft.Boundary ■ Current Owner List(of properties within 50Oft.radius)including the following: ❑ Tax Parcel ID Number(s) ❑ Owner(s)Full Name(s) ❑ Owner(s) Mailing Address(es) ❑ Current Resident&Property Address (if property owner doesn't reside at the property) ■ Mailing Material:Provide❑ white,#10 envelopes with the following affixed to the envelopes: ❑ Postage ❑ Mailing Labels ❑ Return Address labels: 18204 591h Ave NE,Arlington WA 98223 ❑ Grading cut/fill quantity: ❑ Construction Calculation Worksheet ❑ NPDES Permit(if required);See Storm Water Drainage Report,New or Redevelopment Flowcharts ❑ Permit fee due at time of permit submittal Right of Way Submittal Requirements,Type III: Electronic files shall be PDF on USB flash-drive,email,or drop-box ❑ Complete Application. ❑ Construction Plans. ❑ Traffic Control Plan. ❑ Road Closure Request. ❑ Temporary Erosion&Sediment Control(TESC)Plan. ❑ Certificate of Insurance with the City of Arlington named as Additional Insured. ❑ Assurance Device will be required prior to Permit Issuance(Bond or Assignment of Funds). ❑ Engineers Estimated Cost of Construction;$ ❑ Permit fee due at time of permit issuance. Page 2 of 2 WETRABBIT EXPRESS CAR WASH 7530 204th St NE Arlington, Washington 98223 Preliminary Storm water Site Plan M rd i in 6814 Greenwood Avenue N Seattle,WA 98103 T 206.522.9510 www.pacland.com ,,LEA NA �S of W A$�Y�yF �\oP N y, 40514 i � s S ' NAL F�'c�ONAL 2024.04.05 10:33:47-07'00' Prepared By: Travis Cheshire, P.E. Reviewed By:Sean Mallon, P.E. Prepared:December 2023 Revised:April 2024 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section Table of Contents 0 Page EXECUTIVESUMMARY...........................................................................................................................................3 SECTION 1—PROJECT OVERVIEW ..........................................................................................................................5 SECTION 2-EXISTING CONDITIONS SUMMARY.....................................................................................................8 SECTION 3—DEVELOPED CONDITIONS SUMMARY................................................................................................9 SECTION 4-OFF-SITE ANALYSIS...........................................................................................................................10 SECTION 5-CONDITIONS AND REQUIREMENTS...................................................................................................11 SECTION 6-FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN .........................................13 HYDROLOGICANALYSIS.................................................................................................................................................13 EXISTING SITE HYDROLOGY............................................................................................................................................13 DEVELOPED SITE HYDROLOGY........................................................................................................................................14 FLOWCONTROL SYSTEM...............................................................................................................................................15 WATERQUALITY SYSTEM..............................................................................................................................................15 SECTION 7-CONVEYANCE SYSTEM ANALYSIS AND DESIGN.................................................................................16 CONVEYANCE..............................................................................................................................................................16 100-YEAR FLOOD/OVERFLOW CONDITION.......................................................................................................................16 SECTION 8-SPECIAL REPORTS AND STUDIES.......................................................................................................17 SECTION 9-OTHER PERMITSSECTION 8-SPECIAL REPORTS AND STUDIES..........................................................17 SECTION 9-OTHER PERMITS...............................................................................................................................18 SECTION 10-CSWPPP ANALYSIS AND DESIGNSECTION 9-OTHER PERMITS........................................................18 SECTION 10-CSWPPP ANALYSIS AND DESIGN.....................................................................................................19 SECTION 11-OPERATIONS AND MAINTENANCE MANUALSECTION 10-CSWPPP ANALYSIS AND DESIGN...........19 SECTION 11-OPERATIONS AND MAINTENANCE MANUAL..................................................................................22 SECTION 11-OPERATIONS AND MAINTENANCE MANUAL..................................................................................22 APPENDICES: A—BASIN MAPS AND CIVIL PLANS B—DESIGN CALCULATIONS C—GEOTECH REPORT D—STORMWATER OPERATIONS&MAINTENANCE E—CONSTRUCTION SWPPP PACLAND Project# 10700009 Page 2 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington ExecutiveSUMMGry The project site is located along the southeast quadrant of the intersection of 204t"Street NE and State Route 9 and is comprised of two Snohomish County tax parcels.Tax Parcel 310514-001-006-00 is a developed site with a property address of 7530 204th Street NE in Arlington, Washington. This parcel encompasses 0.76 acres of relatively level land with an unoccupied commercial building formerly occupied by Arlington Family Medicine located in the southeastern portion of the parcel.The building is a 3,520 square foot, one-story, wood-framed structure reportedly build in 1984.Asphalt surfaced drive lanes and parking are found to the north,west, and south of the commercial building. The development is serviced by underground utilities and includes an underground stormwater conveyance system. Vegetation includes ornamental plantings in parking lot islands and around the building, a row of large trees along the west and south property lines which appear to serve as a wind block, and a lawn south of the building. Asphalt pavements near the west and south rows of trees exhibit moderate root damage. Tax Parcel 310514-001-010-00 is a relatively level, undeveloped site located east of and adjoining the southern portion of the above discussed developed parcel's east property line.The parcel is irregular in shape and encompasses 0.76 acres. It appears that some underground utilities may be located near the east property line. Vegetation within the undeveloped parcel primarily consists of well-developed tall grasses with dense blackberry brush along its west and north property lines. The project consists of demolishing the existing medical office building, and all existing surface and underground (utilities) site improvements.A+/-4,920 sf Wet Rabbit Express Car Wash (conveyor type) and a +/-450 sf canopy structure for attended, point-of-sale transactions will be constructed along with surface parking for employees,vacuum stalls, landscaping, access drive between 2041" St NE and 771n Ave NE, and supporting utility infrastructure. The project will manage stormwater runoff for both flow control and water quality per 2014 DOE requirements. The roof drainage will be collected and conveyed to the underground stormwater infiltration facility (gravel filled trench) located west of the building beneath the drive aisle.The balance of the site including a portion of the access drive on the neighboring parcel will manage stormwater runoff via multiple catch basin inlets strategically placed at low points. The runoff will then be conveyed underground via a network of storm piping. Prior to entering the infiltration facility oil control will be provided via a CPS separator immediately upstream of the infiltration trench. Stormwater runoff for the neighboring parcel will be managed via a shallow surface infiltration pond.The access road and parking area will collect and convey runoff via sheet flow to the gutter line and discharge to a riprap spillway into the surface pond.The stormwater infiltration systems will infiltrate 100%of all stormwater runoff generated by the project.The native soils below the infiltration facility will complete the water quality treatment process as they meet DOE requirements with respect to organic content and cation exchange capacity(CEC).A piped overflow from the infiltration facility to the municipal system will be provided as an added precaution for large storm events. Design Criteria: The City of Arlington has adopted the 2014 Washington State Department of Ecology Stormwater Management Manual for Western Washington (SMMWW). The site development will result in more than 5,000 sf of new hard surfaces therefore must comply with Minimum Requirements 1-9.Applicable stormwater requirements are outlined in Table 1 below. PACLAND Project#10700009 Page 3 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Table 1 (2014 DOE SMMWW) Jurisdictional Requirements Peak Runoff Control: Match the pre-developed discharge rates from 50%of the 2-year peak flow up through the full 50-year peak flow. Projects discharging directly to approved water bodies may omit this requirement. Water Quality: Upstream of detention: 91%of runoff volume Downstream of detention: Full 2-year release rate Conveyance Design: 25-year event Hydrologic Design Western Washington Hydrology Model (WWHM2012, updated Method: 1/27/23)for water quality and water quantity analysis Proposed Drainage System: The project will manage stormwater runoff for both flow control and water quality per 2014 DOE requirements.The roof drainage will be collected and conveyed to the underground stormwater infiltration facility(gravel filled trench) located west of the building beneath the drive aisle.The balance of the site including a portion of the access drive on the neighboring parcel will manage stormwater runoff via multiple catch basin inlets strategically placed at low points.The runoff will then be conveyed underground via a network of storm piping. Prior to entering the infiltration facility oil control will be provided via a CPS separator immediately upstream of the infiltration trench. Stormwater runoff for the neighboring parcel will be managed via a shallow surface infiltration pond.The access road and parking area will collect and convey runoff via sheet flow to the gutter line and then to a riprap spillway into the surface pond.The stormwater infiltration systems will infiltrate 100%of all stormwater runoff generated by the project.The native soils below the infiltration facility will complete the water quality treatment process as they meet DOE requirements with respect to organic content and cation exchange capacity (CEC). A piped overflow from the infiltration facility to the municipal system will be provided as an added precaution for large storm events. Construction of the new storm drainage facilities will be in accordance with the Washington State Department of Ecology's 2014 SMMWW as required by the City of Arlington. PACLAND Project#10700009 Page 4 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section 7 — Project Overview ?'Itk I,NE ENgMadO MM •• E 41�n1,M i Awm m - - i0�y.91N w y 3 r � a r 1 + I `ol ; °< —r 00 i 'oleiH VE �• `/ I; VICINITY MAP NOT TO SCALE Figure 1.0-Site Location PACLAND Project#10700009 Page 5 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Jk- �C R :,r -ti•-. %.to ti. �.S:� . Figure 1.1 —Aerial Image(from Google Maps) Location: 7530 204t" Street NE, Arlington, Washington, 98223 Section/Township/Range: A portion of the NW%of Section 14,Township 31 North, Range 5 East, W.M. Parcel/Tax Lot: 310514-001-006-00 (0.76 AC) and 310514-001-010-00 (0.76 AC) Disturbed Area: +/- 1.33 AC City, County, State: Arlington, Snohomish County, Washington Governing Agency: City of Arlington Design Criteria: 2014 Washington State Department of Ecology Stormwater Management Manual for Western Washington (SMMWW). PACLAND Project# 10700009 Page 6 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Soils: Geotechnical Report Per the Geotechnical Engineering Report prepared by ZipperGeo, dated March 28, 2024;The subsurface evaluation completed by ZGA for this project included four borings (B-1 through B-4) and one cone penetrometer test (CPT-01). CPT-01 was completed near the center of the proposed car wash development(currently developed western parcel) and extended to a depth of about 60 feet below grade.The CPT exploration included seismic shear wave velocity measurements. Borings B-1 and B-2 were completed in the north and south portions of the western parcel's existing parking lot, respectively, and extended about 36%2 feet below grade. Borings B-3 and B-4 were completed in the undeveloped eastern parcel and extended about 31%2 to 36%2 feet below grade. Groundwater monitoring wells were installed in borings B-1 through B-3 to evaluate changes in groundwater levels through the wet season. At the time drilling groundwater was observed in borings B-1 through B-3 about 25 to 30 below existing ground surface. Soil conditions observed in the site explorations are consistent with normally consolidated glacial recessional outwash deposits of the Marysville Sand Member and generally consist of the following. • Loose to medium dense sand with variable silt and silt with variable sand content in the upper 5 to 7%2 feet. Soil mottling was observed in some of the samples collected in this depth range. • From about 5 to 7%2 feet down to about 15 to 17%2 feet,the outwash generally consists of medium dense to very dense gravelly sand to sandy gravel with trace to some silt. • From about 15 to 17%2 feet to the maximum depth explored at 60 feet below grade,the outwash generally consists of loose to medium dense sand with trace to some silt. Based on the results of the subsurface exploration and analysis, stormwater infiltration systems appear geotechnically feasible. A summary of grain size analysis tests relative to stormwater infiltration is provided below. Summary of Grain Size Analysis Tests Relative to Stormwater Infiltration Sample Initial(unfactored) Sample Design Infiltration Exploration Depth Soil Formation Saturated Hydraulic Number Rates(in/hr) IN Conductivity(In/hr) B 1 S-3 7% Marysville Sand Member 20.2 3.6 B-1 S4 10 Marysville Sand Member 37.1 6.7 B-1 S-5 10 Marysville Sand Member 19.3 3.5 B-2 S-2 5 Marysville Sand Member 3.8 0.7 B-2 S-3 7% Marysville Sand Member 12,6 2.3 B-2 S-4 10 Marysville Sand Member 15.6 2.8 B-2 S-S 15 Marysville Sand Member 14.7 2.6 B-3 S-2 5 Marysville Sand Member 39.9 7.2 a 3 S-3 7% Marysville Sand Member 2.0 0.4 B-3 S-4 10 Marysville Sand Member 4.4 0.8 B-3 S-5 1s Marysville Sand Member 4.5 0.8 B-4 S-2 5 Marysville Sand Member 11.9 2.2 B-4 S-3 7% Marysville Sand Member 8.3 1.5 B-4 S-5 15 Marysville Sand Member 28.4 5.1 :. Includes Correction Factors:CFv=0.5,CFt=0.4,and Urn=0.9 For additional details this report is included in Appendix C. PACLAND Project#10700009 Page 7 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington SectionI Conditions Summary The project site is located along the southeast quadrant of the intersection of 204t"Street NE and State Route 9 and is comprised of two Snohomish County tax parcels.Tax Parcel 310514-001-006-00 is a developed site with a property address of 7530 204th Street NE in Arlington, Washington. This parcel encompasses 0.76 acres of relatively level land with an unoccupied commercial building formerly occupied by Arlington Family Medicine located in the southeastern portion of the parcel.The building is a 3,520 square foot, one-story, wood-framed structure reportedly build in 1984.Asphalt surfaced drive lanes and parking are found to the north,west, and south of the commercial building. The development is serviced by underground utilities and includes an underground stormwater conveyance system.The existing stormwater management system does not appear to be connected to the municipal system, so it is assumed that the stormwater infiltrates into the underlying soils. Vegetation includes ornamental plantings in parking lot islands and around the building, a row of large trees along the west and south property lines which appear to serve as a wind block, and a lawn south of the building.Asphalt pavements near the west and south rows of trees exhibit moderate root damage. Tax Parcel 310514-001-010-00 is a relatively level, undeveloped site located east of and adjoining the southern portion of the above discussed developed parcel's east property line.The parcel is irregular in shape and encompasses 0.76 acres. It appears that some underground utilities may be located near the east property line. Vegetation within the undeveloped parcel primarily consists of well-developed tall grasses with dense blackberry brush along its west and north property lines. Stormwater runoff appears to sheet flow from SE to NE where it either infiltrates directly into the underlying soils or to the drainage ditch along the northern property boundary. PACLAND Project#10700009 Page 8 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington SectionDeveloped Conditions Summary The project will manage stormwater runoff for both flow control and water quality per 2014 DOE requirements.The roof drainage will be collected and conveyed to the underground stormwater infiltration facility(gravel filled trench) located west of the building beneath the drive aisle.The balance of the site including a portion of the access drive on the neighboring parcel will manage stormwater runoff via multiple catch basin inlets strategically placed at low points.The runoff will then be conveyed underground via a network of storm piping. Prior to entering the infiltration facility oil control will be provided via a CPS separator immediately upstream of the infiltration trench. Stormwater runoff for the neighboring parcel will be managed via a shallow surface infiltration pond.The access road and parking area will collect and convey runoff via sheet flow to the gutter line and then to a riprap spillway into the surface pond.The stormwater infiltration systems will infiltrate 100%of all stormwater runoff generated by the project.The native soils below the infiltration facility will complete the water quality treatment process as they meet DOE requirements with respect to organic content and cation exchange capacity (CEC). A piped overflow from the infiltration facility to the municipal system will be provided as an added precaution for large storm events. PACLAND Project#10700009 Page 9 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section i Upstream Analysis Due to the topography of the area,the site does not experience a significant amount of off-site run-on. The public right-of-way to the west and north of the car wash parcel are down gradient.The area west of the car wash parcel is comprised of an existing drainage ditch down gradient from parking area. South of car wash site is an existing parking area which is situated approximately 5' higher than the parking area however it is contained within curbing.The area between the two parking areas is approximately 10—12 feet with no significant stormwater run-on generated due to the tree canopy above. and surrounding properties along the north, south, and west sides of the site are downgradient from the project and minimal stormwater run-on is anticipated. Downstream Analysis This design proposes to route all runoff from target impervious surfaces generated from the project to an underground infiltration facility.The infiltration facility has been designed to infiltrate 100%of all surface water runoff. With a conservatively large trench, it is unlikely that the piped overflow from infiltration facility to the municipal system will be used.Therefore,the proposed development is not anticipated to have a significant impact to the existing downstream stormwater conveyance system. PACLAND Project#10700009 Page 10 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Conditions / I Requirements As required by the 2014 Stormwater Management Manual for Western Washington (SWMMWW) this project is subject to full drainage review.Therefore,the storm drainage design for this project is required to comply with all nine (9) Minimum Requirements.The requirements have been met as follows: Minimum Requirement#1: Preparation of Stormwater Site Plans This project proposes to replace greater than 2,000 square feet of impervious surface;thus, Minimum requirement#1 applies and a Stormwater Site Plan must be prepared for review by the local jurisdiction. Response: This Storm Drainage Report has been prepared to address this requirement. Minimum Requirement#2: Construction Stormwater Pollution Prevention All erosion and sediment control measures shall be governed by the requirements of Department of Ecology's 2014 Stormwater Management Manual for Western Washington and the General Permit for Construction Stormwater.The thirteen elements as identified in the manual and provided below will be incorporated into the TESC plans: Element 1: Preserve Vegetation/Mark Clearing Limits Element 2: Establish Construction Access Element 3: Control Flow Rates Element 4: Install Sediment Controls Element 5: Stabilize Soils Element 6: Protect Slopes Element 7: Protect Drain Inlets Element 8: Stabilize Channels and Outlets Element 9: Control Pollutants Element 10: Control De-watering Element 11: Maintain BMPs Element 12: Manage the Project Element 13: Protect Low Impact Development BMPs Response:Erosion and sediment control measures will be implemented during construction to address the above elements as needed. See Section 10 of this report for a complete description of the construction and erosion control strategies being implemented.A Construction SWPPP will be provided prior to construction permit issuance. Minimum Requirement#3: Source Control of Pollution All known, available and reasonable source control BMPs must be applied to all projects. Source control BMPs must be selected, designed, and maintained according to the 2014 SMMWW. Response: Source control will be provided as needed per Volume IV of the SMMWW. PACLAND Project#10700009 Page 11 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Minimum Requirement#4: Preservation of Natural Drainage Systems and Outfalls Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location,to the maximum extent practicable.The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters and downgradient properties.All outfalls require energy dissipation. Response: The developed site will discharge to the some locations as in the current condition. Storm water runoff within the car wash parcel and a small portion of the neighboring parcel will be routed underground to a subsurface infiltration facility(gravel filled infiltration trench). The neighboring parcel will discharge stormwater runoff to a shallow surface infiltration pond. The proposed site improvements will not alter the existing drainage patterns, thus preserving the natural drainage system/outfall. Construction of the new storm drainage facilities will be in accordance with the Washington State Department of Ecology's 2014 SMMWW, as required by the City of Arlington. Minimum Requirement#S: On-site Stormwater Management Projects shall employ On-site Stormwater Management BMPs in accordance with the following projects thresholds,standards, and lists to infiltrate, disperse, and retain stormwater runoff on-site to the extent feasible without causing flooding or erosion impacts. Response: This project has chosen to meet the Low Impact Development Performance Standard by infiltrating 100%of the stormwater runoff generated by the development.Additionally, amended soils shall be utilized for all disturbed landscape areas per BMP T5.13:Post-Construction Soil Quality and Depth. Minimum Requirement#6: Runoff Treatment Projects in which the total of effective, pollution-generating hard surface (PGHS) is 5,000 SF or more in a threshold discharge area of the project require construction of stormwater treatment facilities. Projects in which the total of pollution-generating pervious surfaces (PGPS) is three-quarters (3/4) of an acre or more in a threshold discharge area, and from which there is a surface discharge in a natural or man- made conveyance system from the site also require treatment facilities. Response: Target Pollutant-generating impervious surfaces(PGIS)associated with the project are comprised primarily of the private roadway, drive aisles and parking areas throughout the site. Runoff from sidewalks that drain to these areas are also included in the PGIS total area. PGIS surfaces from the car wash parcel will be treated for oil control via a CPS O/W separator prior to entering the underground infiltration facility. The native soils below the infiltration facilities(gravel trench and surface pond) will complete the water quality treatment process as they meet DOE requirements with respect to organic content and cation exchange capacity(CEC). See Section 6 of this report for water quality treatment design. Minimum Requirement#7: Flow Control Projects must provide flow control to reduce the impacts of stormwater runoff from hard surfaces and land cover conversions.The requirement below applies to projects that discharge stormwater directly, or indirectly through a conveyance system, into a fresh waterbody. Stormwater discharges shall match developed discharge durations for the range of pre-developed discharge rates from 50%of the pre- developed 2-year peak flow up to the full 50-year peak flow.The pre-developed condition should match a forested land cover. Proper Flow Control BMPs shall be selected and designed according to the current SMMWW. PACLAND Project#10700009 Page 12 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Response:Per SMMWW requirements, existing conditions will be treated as fully forested. Flow control will be achieved through 100%infiltration of the stormwater runoff generated from the project. See Section 6 of this report for flow control design. Minimum Requirement#8:Wetlands Protection The thresholds identified in Minimum Requirement#6 and Minimum Requirement#7 shall also be applied for any discharge to wetlands. Response: This Minimum Requirement is not applicable, as the project does not discharge to a wetland. Minimum Requirement#9: Operation and Maintenance An operation and maintenance manual that is consistent with the provisions in the SMMWW shall be provided for proposed runoff treatment and Flow Control BMPs, and the parties responsible for maintenance and operation shall be identified. Response: A Stormwater Facility Operation and Maintenance Manual will be provided at the time of construction permit submittal. Section 6 - Flow Control and Water Quality Facility Analysis and Design The City of Arlington standards reference the 2014 SMMWW and require that the developed discharge durations match the pre-developed durations for 50%of the pre-developed 2-year peak flow up to the full 50-year peak flow.The pre-developed condition shall be considered as a forested land cover. Hydrologic Analysis Hydrologic analysis for evaluating the flow frequency comparison between the existing conditions and proposed conditions for the project was performed using the Washington Department of Ecology's Wester Washington Hydrologic Method of computer modeling WWHM2012 program.The model utilizes design data for specific soil types and vegetative covers to simulate runoff.The software program routes the flows generated from the basin analysis through a proposed conveyance system to storm water BMPs or structural detention facilities.The model is designed to meet the standard requirements stated in the Department of Ecology's Stormwater Management Manual for Western Washington. A single model was created to analyze the existing conditions in comparison with the proposed conditions to determine the anticipated increase in peak flows for the project. Refer to Appendix B,for model results. Existing Site Hydrology Tax Parcel 310514-001-006-00 (Parcel 1) encompasses 0.76 acres of relatively level land with an unoccupied commercial building formerly occupied by Arlington Family Medicine located in the southeastern portion of the parcel.The building is a 3,520 square foot, one-story,wood-framed structure reportedly build in 1984. Asphalt surfaced drive lanes and parking are found to the north, west, and south of the commercial building.The development is serviced by underground utilities and includes an underground stormwater conveyance system.The existing stormwater management system does not appear to be connected to the municipal system, so it is assumed that the stormwater PACLAND Project#10700009 Page 13 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington infiltrates into the underlying soils. Vegetation includes ornamental plantings in parking lot islands and around the building, a row of large trees along the west and south property lines which appear to serve as a wind block, and a lawn south of the building. Tax Parcel 310514-001-010-00 (Parcel 2) is a relatively level, undeveloped site located east of and adjoining the southern portion of the above discussed developed parcel's east property line.The parcel is irregular in shape and encompasses 0.76 acres. Vegetation within the undeveloped parcel primarily consists of well-developed tall grasses with dense blackberry brush along its west and north property lines. Stormwater runoff appears to sheet flow from SE to NE where it either infiltrates directly into the underlying soils or to the drainage ditch along the northern property boundary. The pre-developed conditions for the project site are shown in Table 2A&2B below. Existing peak runoff rates were determined using the WWHM2012 modeling software and the calculations can be found in Appendix B. Table 2A—Car Wash Site (Parcel 1) Pre-Developed(Existing)Conditions Land Cover Area (AC) Roof 0.08 Landscape 0.22 Sidewalk 0.04 Pavement/Gravel 0.42 Total 0.76 *Per the requirements of the SMMWW,all existing conditions shall be modeled as forested conditions. Table 2B—Future Development Site(Parcel 2) Pre-Developed(Existing)Conditions Land Cover Area (AC) Undeveloped—Grass& 0.76 Shrubs Total 0.76 *Per the requirements of the SMMWW,all existing conditions shall be modeled as forested conditions. Developed Site Hydrology The project will manage stormwater runoff for both flow control and water quality per 2014 DOE requirements.The roof drainage will be collected and conveyed to the underground stormwater infiltration facility(gravel filled trench) located west of the building beneath the drive aisle.The balance of the site including a portion of the access drive on the neighboring parcel will manage stormwater runoff via multiple catch basin inlets strategically placed at low points.The runoff will then be conveyed underground via a network of storm piping. Prior to entering the infiltration facility oil control will be provided via a CPS separator immediately upstream of the infiltration trench. Stormwater runoff for the neighboring parcel will be managed via a shallow surface infiltration pond.The access road and parking area will collect and convey runoff via sheet flow to the gutter line and then to a riprap spillway into the surface pond.The stormwater infiltration systems will infiltrate 100%of all stormwater runoff generated by the project.The native soils below the infiltration facility will complete the water quality treatment process as they meet DOE requirements with respect to organic content and cation exchange capacity PACLAND Project#10700009 Page 14 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington (CEC). A piped overflow from the infiltration facility to the municipal system will be provided as an added precaution for large storm events. Construction of the new storm drainage facilities will be in accordance with the Washington State Department of Ecology's 2014 SMMWW, as required by the City of Arlington. Refer to Appendix B for detailed WWHM analysis results.The developed conditions for the project site are shown in Tables 3A&3B below. Table 3A-Car Wash Site (Sub basin A) Developed(Proposed)Conditions Land Cover Area (AC) Roof/Canopy 0.137 Landscape 0.240 Sidewalk 0.026 Pavement 0.433 Total 0.836 Table 3B- Future Development Site(Sub basin B) Developed(Proposed)Conditions Land Cover Area (AC) Roof/Canopy 0.000 Landscape 0.472 Sidewalk 0.000 Pavement 0.209 Total 0.681 The area within the public right-of-way has been excluded from developed conditions as the stormwater runoff from this area is currently managed by the municipal stormwater system. Flow Control System The project will manage stormwater runoff for flow control per 2014 DOE requirements by implementing a below grade infiltration system.The infiltration gallery is 25'W x 1001 x 4'D and comprised of gravel trench with a network of perforated pipes configured as a manifold.The system has been designed to infiltrate 100%of the stormwater runoff generated by the by the car wash parcel (sub basin A).The surface infiltration pond on the adjacent parcel (sub basin B) has been designed to infiltrate 100%of the stormwater runoff generated by the access road and parking area. Refer to Appendix B,for WWHM model results. Water Quality System Per the 2014 SWMMWW,the water quality facilities shall be sized to treat the 91s' percentile of the 24- hour runoff model upstream of detention and the full 2-year release rate downstream of detention. Upstream of the infiltration facility oil control will be provided via a CPS O/W separator.The native soils below the infiltration facility will complete the water quality treatment process as they meet DOE requirements with respect to SSC-6 Soil physical and Chemical Suitability for Treatment. PACLAND Project#10700009 Page 15 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Conveyance System AnGAISiS and Design Conveyance On-site storm water conveyance shall be calculated through gravity flow analysis of the piping network. Based on a 100-year storm event, peak runoff shall be routed through the system and determined to be adequate. A Uniform Flow Analysis utilizing Manning's equation was employed with a Manning's "n" value of 0.012. Manning's equation - _ 1.49 x A x R Z Q /3 x S 1/2 n With: Q= Flow from 100-year storm event (1.36 CFS) n = Manning's Roughness Coefficient (0.012) A= Flow Area (SF) R= Hydraulic Radius =Area/Wetted Perimeter(LF) S =Slope of the pipe (ft/ft) Conveyance calculations are included in Appendix B. 100-Year Flood/Overflow Condition Review of the current FEMA FIRM maps (map#53061C0392F) indicates that the project site lies within the Zone designation X, meaning the subject property is within an area determined to be outside the 500-year floodplain. During extreme storm events the stormwater runoff will pond and then sheet flow west to the private road tract area. The stormwater system for this project has been designed to address storm events in accordance with design criteria described previously. In the event of a larger storm, it is unlikely that the system would fail. A piped overflow to the municipal system has been incorporated into the design as an added precaution during extreme storm events. PACLAND Project#10700009 Page 16 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section i - speCiGl Reports I I Studies The following Special Reports and Studies were used or have been completed for this project: • Arborist Report, prepared by Greenforest Incorporated, dated October 12, 2023. • Geotechnical Engineering Investigation Report, prepared by ZipperGeo, dated March 28, 2024. • Phase 1 Environmental Site Assessment, prepared by ZipperGeo, dated October 24, 2023. • Wetland Letter of Findings, prepared by Harmsen, dated October 24, 2023. • Traffic Impact Analysis, prepared by Transpogroup, dated December 2023. PACLAND Project#10700009 Page 17 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section • Permits The following governmental approvals or permits will likely be required for this project: • Zoning Permit • Design Review • SEPA • Construction Permit(Civil) • Building Permit • Construction Stormwater General Permit/NPDES Permit—Department of Ecology These permits will require approval by the City of Arlington and Department of Ecology. PACLAND Project#10700009 Page 18 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section 70 - CSWPPP Analysis and Design All erosion and sediment control measures shall be governed by the requirements Department of Ecology's 2014 Storm Water Management for Western Washington. A Stormwater Pollution Prevention Plan (SWPPP)will be prepared for this project. A temporary erosion and sedimentation control plan will be prepared to assist the contractor in complying with these requirements. The Erosion and Sediment Control (ESC) plan will be included with the construction plans. 1. Construction Sequence and Procedure The proposed development will include an erosion/sedimentation control plan designed to prevent sediment-laden run-off from leaving the site during construction. The erosion potential of the site is influenced by four major factors: soil characteristics,vegetative cover,topography, and climate. Erosion/sedimentation control is achieved by a combination of structural measures, cover measures, and construction practices that are tailored to fit the specific site. The contractor will be responsible for implementing the following erosion control and storm water management control measures. The contractor may designate these tasks to certain subcontractors as they see fit, but the ultimate responsibility for implementing these controls and ensuring their proper functioning remains with the contractor. The order of activities will be as follows. Phase 1 1. Prior to any construction work on the site, representatives from the City of Arlington must approve the storm water pollution prevention plan. 2. Mark clearing limits. 3. Install inlet protection to all existing catch basins. 4. Install temporary stabilized construction entrance. Existing paved area to remain and be utilized until construction phasing requires removal. 5. Install perimeter silt fences, interceptor swales, etc. 6. Install sediment control pond and/or tank(s). 7. Remove any existing structures that may be on site. 8. Protect and stabilize slopes. 9. Begin clearing and grubbing operations. Clearing and grubbing done from October 1st through April 30t" is authorized as long as there are erosion and sediment control measures. 10. Commence site grading. Phase 2 1. Disturbed areas of the site where construction activity has ceased for more than 7 days between May 1 and September 30 or 2 days between October 1 and April 30 shall be temporarily seeded and watered. 2. Construct building pad and install concrete wash out area. 3. Construct permanent storm water facilities. Remove temporary sedimentation ponds. 4. Install utilities, underdrains, storm sewers, curbs and gutters. 5. Install inlet/outlet protection at the locations of all grate inlets, curb inlets, and at the ends of all exposed storm sewer pipes. 6. Prepare site for paving. Finalize pavement subgrade preparation. PACLAND Project#10700009 Page 19 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 7. Remove inlet protection around inlets and manholes no more than 48 hours prior to placing stabilized base course. 8. Install base material as required for pavement. Pave site. Do not pave over catch basins. 9. Complete final grading in non-parking areas and install permanent seeding and planting. 10. Remove silt fencing only after all paving is complete and exposed surfaces are stabilized. 11. Remove temporary construction exits only prior to pavement construction in these areas (These areas are to be paved last). The degree of erosion risk on the proposed project site is high given the proximity to a steep slope.The contractor shall refer to the geotechnical report for further recommendations. 2. Temporary Soil Stabilization Temporary stabilization practices for this project include: • Temporary seeding and planting of all unpaved areas using the hydro-mulching grass seeding technique. • Mulching exposed areas. • Installation of rolled erosion control products. Structural practices for this project include the following. Refer to the Erosion Control plans for specific locations and details: • Inlet protection using fiber fabric. • Perimeter protection using silt fences. • Stabilized construction entrance/exit points and staging area. • Temporary sediment tank. • Silt fence. Daily inspection of the erosion control measures will be required during construction. Any sediment buildup shall be removed and disposed offsite at an appropriate disposal facility. Vehicle tracking of mud off-site shall be avoided. A gravel construction entrance/exit will be installed at a location to enter the site. The construction entrance/exit is a minimum requirement and may be supplemented if tracking of mud onto public streets becomes excessive. In the event that mud is tracked off site, it shall be swept and disposed of offsite on a daily basis. Because vegetative cover is the most important form of erosion control, construction practices must adhere to stringent cover requirements. More specifically,the contractor will not be allowed to leave soils open for more than 7 days between May 1st and September 30th and 2 days between October 1st and April 30th. Soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. Applicable practices include, but are not limited to,temporary and permanent seeding, sodding, mulching, plastic covering, and soil application of polyacrylamide. Soil stockpiles must be stabilized from erosion, protected with sediment trapping measures, and,where possible, be located away from storm drain inlets, waterways and drainage channels. PACLAND Project#10700009 Page 20 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 3. Temporary Sediment Control Construction storm water shall be detained on-site during construction in a temporary sediment control tank located at the northeast corner of the project.The DOE requires temporary sediment storage to be designed to manage the 2-year developed peak flow. 4. Permanent Erosion Control and Site Restoration Upon completion of the project, areas of the site that are not stabilized with paving, rooftops, or landscaping as shown on the site plans will be protected with either grass, ground cover/plantings or existing vegetation as shown on the Landscape Plans. S. Inspection Sequence The construction site operator will periodically inspect its sites. Because our project disturbs more than one acre, a certified erosion and sediment control lead will be identified within the SWPPP. This individual will be present on site or on call at all times. 6.Control of Pollutants Other than Sediments Pollutants shall be controlled on the work site through the utilization of a centralized area for equipment, a concrete truck washout, and an area designated for temporary storage of debris and stockpiled materials. PACLAND Project#10700009 Page 21 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington A manual detailing the operations and maintenance for all privately maintained conveyance and collection facilities will be provided prior to construction permit issuance. PACLAND Project#10700009 Page 22 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Appendix A — Basin Maps & Civil Plans PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 0 x w =R a ■ a @ :@ W Q gg Z p Z B Z Q H m l j j~�♦ Q I ,,,♦ Cr Q W N $ a ♦, CD w 2 p , ♦ , xo0 W N H 3 I F O Q 4 m^J Ld Ld g HJp Q 2 4# , ?i J# -� W � � W Q 2 , , W , o ---------'&--------------------------� $ 1 y ct 1 ----------------------------------J �3 W a 2 U z� 00 o� �H 4 ry H Z Z 4 d y^ZO�II-fdOZ'81�0 aP3-Y3tlY-tlY11M\SY3tlY�llpddf6�S1A0C�Al 15 H1/02 O[SL�1@BOtl 13M\"°�`-''�'v'-,a'iLuyvul�.=: PACLAND Project#10980002 w@ Rabbi Express Car Wash k7mw»rslePlan Arlington,Washington 9 § ƒ \~ U § \\. | q5 � Lou o ƒ # LU aE % 7 LU . E0 ° §$) -(¥ `A, A� �.. u 0 w�. . a a.. �� . m 7 ! 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I w W Q � W 2 i 'r W U NO oz w � � -I I o F w h I I1 I �7r— i I ID A f � I I I I I -JI I' fl i �: I ` 0 wast¢j- ZDZ to A4 wo aoszxrxr,�x�\3w is wwz aseUieara i \web w>buiwow\s w@ Rabbi Express Car Wash k7mw»rslePlan Arlington,Washington , 7 Id | | | $ , o , . k I n . §Z2 Ilia 2§k =e >3A # ] ) v m w 0 z §$§ ƒ $ m | G \ \ } / � � { � ----------3 �� , ---—~ 6 j ------------- � � ! � |� | ! _aZDZww 1 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Appendix 6 — Design Calculations • Conveyance • WWHM Analysis PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington MANNING'S EQUATION FOR PIPE FLOW Project: WET RABBIT Location: ARLINGTON. WA By: TAC Date: Chk. By: SMM Date: mdo version 12.8.00 Clear Data u Entry Cells INPUT D= 12 inches d= 11.28 inches Mannings Formula d n= 0.012 mannings coeff D 0 56.7 degrees Q=(1.486/n)ARnI"'S'1 S= 0.005 slope in/in R-A,'P A=cross sectional area P=wetted perimeter V=(1.49/n)R,"''S'`2 S=slope of channel Q=V x A n=Manning's roughness coefficient Solution to Mannings Equation Manning's n-values Welled y rau is Area.ftz Perimeter,ft Radius,ft velocity ft/s flow.cfs PVC 0.01 0.77 2.65 0.29 3.83 2.94 PE(<9"dia) 0.015 PE(>12"dia) 0.02 PE(9-12"dia) 0.017 CMP 0.025 ADS N12 0,012 Created by: Mike O'Shea HCMP 0.023 Conc 0.013 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington WWHM2012 PROJECT REPORT FLOW CONTROL SUB BASIN A PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington General Model Information WWHM2012 Project Name:Flow Control Sub basin A Site Name: Arlington Wet Rabbit Site Address: 7530 204th St NE City: Arlington Report Date: 3/29/2024 Gage: Everett Data Start: 1948/10/01 Data End: 2009/09/30 Timestep: 15 Minute Precip Scale: 1.200 Version Date: 2023/01/27 Version: 4.2.19 POC Thresholds Low Flow Threshold for POC1: 50 Percent of the 2 Year High Flow Threshold for POC1: 50 Year Flow Control Sub basin A 3/29/2024 3:21:51 PM Page 2 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Landuse Basin Data Predeveloped Land Use Sub Basin A (Pre) Bypass: No Groundwater: No Pervious Land Use acre C, Forest, Flat 0.836 Pervious Total 0.836 Impervious Land Use acre Impervious Total 0 Basin Total 0.836 Flow Control Sub basin A 3/29/2024 3:21:51 PM Page 3 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Mitigated Land Use Sub Basin A (Post) Bypass: No GrounclWater: No Pervious Land Use acre C, Lawn, Flat 0.24 Pervious Total 0.24 Impervious Land Use acre ROOF TOPS FLAT 0.137 SIDEWALKS FLAT 0.026 PARKING FLAT 0.433 Impervious Total 0.596 Basin Total 0.836 Flow Control Sub basin A 3 29 2024 3:21:51 PM Page 4 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Routing Elements Predeveloped Routing Flow Control Sub basin A 3 29 2024 3:21:51 PM Page 5 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Mitigated Routing Gravel Trench Bed 1 Bottom Length: 25.00 ft. Bottom Width: 100.00 ft. Trench bottom slope 1: 0 To 1 Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer: 3.5 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: 2.6 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 141.265 Total Volume Through Riser(ac-ft.): 0 Total Volume Through Facility (ac-ft.): 141.265 Percent Infiltrated: 100 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 3 ft. Riser Diameter: 12 in. Element Flows To: Outlet 1 Outlet 2 Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-%) Discharge(cfs) Infilt(cfs) 0.0000 0.057 0.000 0.000 0.000 0.0389 0.057 0.000 0.000 0.150 0.0778 0.057 0.001 0.000 0.150 0.1167 0.057 0.002 0.000 0.150 0.1556 0.057 0.003 0.000 0.150 0.1944 0.057 0.004 0.000 0.150 0.2333 0.057 0.005 0.000 0.150 0.2722 0.057 0.006 0.000 0.150 0.3111 0.057 0.007 0.000 0.150 0.3500 0.057 0.008 0.000 0.150 0.3889 0.057 0.008 0.000 0.150 0.4278 0.057 0.009 0.000 0.150 0.4667 0.057 0.010 0.000 0.150 0.5056 0.057 0.011 0.000 0.150 0.5444 0.057 0.012 0.000 0.150 0.5833 0.057 0.013 0.000 0.150 0.6222 0.057 0.014 0.000 0.150 0.6611 0.057 0.015 0.000 0.150 0.7000 0.057 0.016 0.000 0.150 0.7389 0.057 0.017 0.000 0.150 0.7778 0.057 0.017 0.000 0.150 0.8167 0.057 0.018 0.000 0.150 0.8556 0.057 0.019 0.000 0.150 0.8944 0.057 0.020 0.000 0.150 Flow Control Sub basin A 3/29/2024 3:21:51 PM Page 6 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 0.9333 0.057 0.021 0.000 0.150 0.9722 0.057 0.022 0.000 0.150 1.0111 0.057 0.023 0.000 0.150 1.0500 0.057 0.024 0.000 0.150 1.0889 0.057 0.025 0.000 0.150 1.1278 0.057 0.025 0.000 0.150 1.1667 0.057 0.026 0.000 0.150 1.2056 0.057 0.027 0.000 0.150 1.2444 0.057 0.028 0.000 0.150 1.2833 0.057 0.029 0.000 0.150 1.3222 0.057 0.030 0.000 0.150 1.3611 0.057 0.031 0.000 0.150 1.4000 0.057 0.032 0.000 0.150 1.4389 0.057 0.033 0.000 0.150 1.4778 0.057 0.033 0.000 0.150 1.5167 0.057 0.034 0.000 0.150 1.5556 0.057 0.035 0.000 0.150 1.5944 0.057 0.036 0.000 0.150 1.6333 0.057 0.037 0.000 0.150 1.6722 0.057 0.038 0.000 0.150 1.7111 0.057 0.039 0.000 0.150 1.7500 0.057 0.040 0.000 0.150 1.7889 0.057 0.041 0.000 0.150 1.8278 0.057 0.042 0.000 0.150 1.8667 0.057 0.042 0.000 0.150 1.9056 0.057 0.043 0.000 0.150 1.9444 0.057 0.044 0.000 0.150 1.9833 0.057 0.045 0.000 0.150 2.0222 0.057 0.046 0.000 0.150 2.0611 0.057 0.047 0.000 0.150 2.1000 0.057 0.048 0.000 0.150 2.1389 0.057 0.049 0.000 0.150 2.1778 0.057 0.050 0.000 0.150 2.2167 0.057 0.050 0.000 0.150 2.2556 0.057 0.051 0.000 0.150 2.2944 0.057 0.052 0.000 0.150 2.3333 0.057 0.053 0.000 0.150 2.3722 0.057 0.054 0.000 0.150 2.4111 0.057 0.055 0.000 0.150 2.4500 0.057 0.056 0.000 0.150 2.4889 0.057 0.057 0.000 0.150 2.5278 0.057 0.058 0.000 0.150 2.5667 0.057 0.058 0.000 0.150 2.6056 0.057 0.059 0.000 0.150 2.6444 0.057 0.060 0.000 0.150 2.6833 0.057 0.061 0.000 0.150 2.7222 0.057 0.062 0.000 0.150 2.7611 0.057 0.063 0.000 0.150 2.8000 0.057 0.064 0.000 0.150 2.8389 0.057 0.065 0.000 0.150 2.8778 0.057 0.066 0.000 0.150 2.9167 0.057 0.067 0.000 0.150 2.9556 0.057 0.067 0.000 0.150 2.9944 0.057 0.068 0.000 0.150 3.0333 0.057 0.069 0.064 0.150 3.0722 0.057 0.070 0.205 0.150 3.1111 0.057 0.071 0.389 0.150 3.1500 0.057 0.072 0.604 0.150 Flow Control Sub basin A 3/29/2024 3:21:51 PM Page 7 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 3.1889 0.057 0.073 0.838 0.150 3.2278 0.057 0.074 1.080 0.150 3.2667 0.057 0.075 1.318 0.150 3.3056 0.057 0.075 1.540 0.150 3.3444 0.057 0.076 1.736 0.150 3.3833 0.057 0.077 1.900 0.150 3.4222 0.057 0.078 2.029 0.150 3.4611 0.057 0.079 2.126 0.150 3.5000 0.057 0.080 2.203 0.150 Flow Control Sub basin A 3 29 2024 3:21:51 PM Page 8 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Analysis Results POC 1 J e. oa Cri IL Jt3 .�.-w•'r JCI ..- Is-5 Ilri< 'iF I'i--I t lii JJt ..........��.�......,...... Jpt N BA 9J 95 95 49935 i• + Predeveloped x Mitigated Predeveloped Landuse Totals for POC#1 Total Pervious Area: 0.836 Total Impervious Area: 0 Mitigated Landuse Totals for POC#1 Total Pervious Area: 0.24 Total Impervious Area: 0.596 Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC#1 Return Period Flow(cfs) 2 year 0.02809 5 year 0.043091 10 year 0.05466 25 year 0.071212 50 year 0.084997 100 year 0.100073 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 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC#1 Year Predeveloped Mitigated 1949 0.028 0.000 1950 0.029 0.000 1951 0.026 0.000 1952 0.020 0.000 1953 0.017 0.000 1954 0.092 0.000 1955 0.036 0.000 1956 0.032 0.000 1957 0.040 0.000 1958 0.029 0.000 Flow Control Sub basin A 3 29 2024 3:21:51 PM Page 9 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 1959 0.028 0.000 1960 0.026 0.000 1961 0.050 0.000 1962 0.025 0.000 1963 0.041 0.000 1964 0.029 0.000 1965 0.024 0.000 1966 0.014 0.000 1967 0.029 0.000 1968 0.035 0.000 1969 0.086 0.000 1970 0.020 0.000 1971 0.032 0.000 1972 0.024 0.000 1973 0.022 0.000 1974 0.048 0.000 1975 0.020 0.000 1976 0.020 0.000 1977 0.017 0.000 1978 0.020 0.000 1979 0.056 0.000 1980 0.026 0.000 1981 0.021 0.000 1982 0.027 0.000 1983 0.046 0.000 1984 0.028 0.000 1985 0.033 0.000 1986 0.078 0.000 1987 0.037 0.000 1988 0.019 0.000 1989 0.020 0.000 1990 0.026 0.000 1991 0.027 0.000 1992 0.021 0.000 1993 0.017 0.000 1994 0.019 0.000 1995 0.027 0.000 1996 0.047 0.000 1997 0.093 0.000 1998 0.017 0.000 1999 0.022 0.000 2000 0.017 0.000 2001 0.007 0.000 2002 0.025 0.000 2003 0.020 0.000 2004 0.034 0.000 2005 0.023 0.000 2006 0.062 0.000 2007 0.049 0.000 2008 0.069 0.000 2009 0.021 0.000 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC#1 Rank Predeveloped Mitigated 1 0.0930 0.0000 2 0.0918 0.0000 3 0.0856 0.0000 Flow Control Sub basin A i L t.I PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 4 0.0784 0.0000 5 0.0692 0.0000 6 0.0623 0.0000 7 0.0562 0.0000 8 0.0499 0.0000 9 0.0493 0.0000 10 0.0482 0.0000 11 0.0468 0.0000 12 0.0456 0.0000 13 0.0406 0.0000 14 0.0395 0.0000 15 0.0374 0.0000 16 0.0362 0.0000 17 0.0352 0.0000 18 0.0336 0.0000 19 0.0334 0.0000 20 0.0319 0.0000 21 0.0319 0.0000 22 0.0292 0.0000 23 0.0290 0.0000 24 0.0287 0.0000 25 0.0286 0.0000 26 0.0283 0.0000 27 0.0281 0.0000 28 0.0275 0.0000 29 0.0274 0.0000 30 0.0270 0.0000 31 0.0268 0.0000 32 0.0264 0.0000 33 0.0263 0.0000 34 0.0262 0.0000 35 0.0257 0.0000 36 0.0255 0.0000 37 0.0246 0.0000 38 0.0244 0.0000 39 0.0235 0.0000 40 0.0234 0.0000 41 0.0224 0.0000 42 0.0223 0.0000 43 0.0211 0.0000 44 0.0206 0.0000 45 0.0206 0.0000 46 0.0202 0.0000 47 0.0202 0.0000 48 0.0202 0.0000 49 0.0202 0.0000 50 0.0200 0.0000 51 0.0197 0.0000 52 0.0196 0.0000 53 0.0194 0.0000 54 0.0187 0.0000 55 0.0171 0.0000 56 0.0170 0.0000 57 0.0170 0.0000 58 0.0170 0.0000 59 0.0168 0.0000 60 0.0143 0.0000 61 0.0067 0.0000 Flow Control Sub basin A T"M PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Flow Control Sub basin A 3 29'2024 3 23.35 PM Page 12 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Duration Flows The Facility PASSED Flow(cfs) Predev Mit Percentage Pass/Fail 0.0140 19622 0 0 Pass 0.0148 16989 0 0 Pass 0.0155 14679 0 0 Pass 0.0162 12735 0 0 Pass 0.0169 10925 0 0 Pass 0.0176 9445 0 0 Pass 0.0183 8173 0 0 Pass 0.0191 7075 0 0 Pass 0.0198 6139 0 0 Pass 0.0205 5313 0 0 Pass 0.0212 4654 0 0 Pass 0.0219 4070 0 0 Pass 0.0226 3551 0 0 Pass 0.0234 3136 0 0 Pass 0.0241 2761 0 0 Pass 0.0248 2447 0 0 Pass 0.0255 2145 0 0 Pass 0.0262 1894 0 0 Pass 0.0269 1657 0 0 Pass 0.0277 1508 0 0 Pass 0.0284 1370 0 0 Pass 0.0291 1250 0 0 Pass 0.0298 1154 0 0 Pass 0.0305 1069 0 0 Pass 0.0312 1009 0 0 Pass 0.0320 949 0 0 Pass 0.0327 888 0 0 Pass 0.0334 825 0 0 Pass 0.0341 777 0 0 Pass 0.0348 734 0 0 Pass 0.0355 686 0 0 Pass 0.0363 648 0 0 Pass 0.0370 622 0 0 Pass 0.0377 602 0 0 Pass 0.0384 583 0 0 Pass 0.0391 561 0 0 Pass 0.0398 538 0 0 Pass 0.0406 506 0 0 Pass 0.0413 487 0 0 Pass 0.0420 473 0 0 Pass 0.0427 457 0 0 Pass 0.0434 440 0 0 Pass 0.0441 424 0 0 Pass 0.0449 409 0 0 Pass 0.0456 394 0 0 Pass 0.0463 380 0 0 Pass 0.0470 368 0 0 Pass 0.0477 353 0 0 Pass 0.0484 341 0 0 Pass 0.0492 333 0 0 Pass 0.0499 322 0 0 Pass 0.0506 313 0 0 Pass 0.0513 302 0 0 Pass Flow Control Sub basin A 3 9-;J2�; _35 PP.I �ciga 3 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 0.0520 293 0 0 Pass 0.0527 284 0 0 Pass 0.0535 276 0 0 Pass 0.0542 266 0 0 Pass 0.0549 257 0 0 Pass 0.0556 241 0 0 Pass 0.0563 234 0 0 Pass 0.0570 226 0 0 Pass 0.0578 212 0 0 Pass 0.0585 205 0 0 Pass 0.0592 195 0 0 Pass 0.0599 187 0 0 Pass 0.0606 177 0 0 Pass 0.0613 166 0 0 Pass 0.0621 160 0 0 Pass 0.0628 150 0 0 Pass 0.0635 146 0 0 Pass 0.0642 135 0 0 Pass 0.0649 128 0 0 Pass 0.0656 120 0 0 Pass 0.0664 111 0 0 Pass 0.0671 99 0 0 Pass 0.0678 85 0 0 Pass 0.0685 75 0 0 Pass 0.0692 63 0 0 Pass 0.0699 59 0 0 Pass 0.0707 56 0 0 Pass 0.0714 50 0 0 Pass 0.0721 42 0 0 Pass 0.0728 39 0 0 Pass 0.0735 37 0 0 Pass 0.0742 36 0 0 Pass 0.0750 30 0 0 Pass 0.0757 28 0 0 Pass 0.0764 26 0 0 Pass 0.0771 19 0 0 Pass 0.0778 16 0 0 Pass 0.0785 13 0 0 Pass 0.0793 8 0 0 Pass 0.0800 6 0 0 Pass 0.0807 5 0 0 Pass 0.0814 4 0 0 Pass 0.0821 4 0 0 Pass 0.0828 3 0 0 Pass 0.0836 3 0 0 Pass 0.0843 3 0 0 Pass 0.0850 3 0 0 Pass Flow Control Sub basin A 3129 2024 3:23:35 PM PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Water Quality Water Quality BMP Flow and Volume for POC#1 On-line facility volume: 0.079 acre-feet On-line facility target flow: 0.112 cfs. Adjusted for 15 min: 0.112 cfs. Off-line facility target flow: 0.0632 cfs. Adjusted for 15 min: 0.0632 cfs. Flow Control Sub basin A 312T2024 3:23:35 PM Page 15 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington LID Report tJD Technique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Water Comment Treatment 7 PleedS Through Volume Volume Volume Quality Treatment Facility (ac-11) Infiltration Infihrated Trealed (ac-fi) (ac-n) Credit Gravel Trench Bed 1 POC ❑ 12855 ❑ 10000 Total Volume Infiltrated 128.55 0.00 000 10000 0.00 0%No Treat Credit Duration Comphartee with uD Standard Analysis 8%of 2-yr to 50%of 2-W Result= Passed Flow Control Sub basin A 3129 2024 3 23.35 PM Page 16 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. Flow Control Sub basin A 3 29 2024 3:23:55 PM Page 17 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Appendix Predeveloped Schematic 0 Sub Basin (Pre) 0.84ac Flow Control Sub basin A 3 29 2024 3:23:55 PM Page 18 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Mitigated Schematic i wn ub Basin (Post) .84ac SI Gravel ~� Trench Bed 1 Flow Control Sub basin A 3 29 2024 3:23:56 PM Page 19 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 Flow Control Sub basin A.wdm MESSU 2.5 PreFlow Control Sub basin A.MES 27 PreFlow Control Sub basin A.L61 28 PreFlow Control Sub basin A.L62 30 POCFlow Control Sub basin. Al.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 10 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE. DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Sub Basin A (Pre) MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM It # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 10 C, Forest, Flat 1 1 1 1 27 0 END GEN-INFO *** Section. PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 10 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 10 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 20 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 10 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 10 0 4.5 0.08 400 0.05 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 10 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 10 0.2 0.5 0.35 6 0.5 0.7 END PWAT-PARM4 PWAT-STATEI <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 10 0 0 0 0 2.5 1 0 END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section. IWATER*** ACTIVITY <PLS > ************* Active Sections # - # ATMP SNOW TWAT SLD IWG IQAL *** END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW TWAT SLD IWG IQAL ********* END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 TWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END TWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATEI Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 21 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Sub Basin A (Pre)*** PERLND 10 0.836 COPY 501 12 PERLND 10 0.836 COPY 501 13 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 TNPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PINK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC Al A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1.2 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1.2 IMPLND 1 999 EXTNL PREC Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 22 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNT, PETTNP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY TNPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 END MASS-LINK END RUN Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 23 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Mitigated UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>** <-ID-> *** WDM 26 Flow Control Sub basin A.wdm MESSU 2.5 MitFlow Control Sub basin A.MES 27 MitFlow Control Sub basin A.L61 28 MitFlow Control Sub basin A.L62 30 POCFlow Control Sub basin. Al.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 16 TMPI.ND 4 IMPLND 8 IMPLND 11 RCHRES 1 COPY 1 COPY 501 DTSPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INF01 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Gravel Trench Bed 1 MAX 1 2 30 9 END DISPLY-INFOl END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 16 C, Lawn, Flat 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 16 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 24 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 16 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRTNT-TNFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 16 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARMI PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 16 0 4.5 0.03 400 0.05 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 16 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW TRC LZETP *** 16 0.1 0.25 0.25 6 0.5 0.25 END PWAT-PARM4 PWAT-STATEI <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 16 0 0 0 0 2.5 1 0 END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 4 ROOF TOPS/FLAT 1 1 1 27 0 8 SIDEWALKS/FLAT 1 1 1 27 0 11 PARKING/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 4 0 0 1 0 0 0 8 0 0 1 0 0 0 11 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <TLS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 4 0 0 4 0 0 4 1 9 8 0 0 4 0 0 0 1 9 11 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 4 0 0 0 0 0 8 0 0 0 0 0 11 0 0 0 0 0 Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 25 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington END IWAT-PARMl IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 4 400 0.01 0.1 0.1 8 400 0.01 0.1 0.1 11 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 4 0 0 8 0 0 11 0 0 END IWAT-PARM3 IWAT-STATEI. <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 4 0 0 8 0 0 11 0 0 END TWAT-STATEI END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Sub Basin A (Post)*** PERLND 16 0.24 RCHRES 1 2 PERLND 16 0.24 RCHRES 1 3 IMPLND 4 0.137 RCHRES 1 5 IMPLND 8 0.026 RCHRES 1 5 IMPLND 11 0.433 RCHRES 1 5 ******Routing****** PERLND 16 0.24 COPY 1 12 IMPLND 4 0.137 COPY 1 15 IMPLND 8 0.026 COPY 1 15 IMPLND 11 0.433 COPY 1 15 PERLND 16 0.24 COPY 1 13 RCHRES 1 1 COPY 501 17 END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> It <Name> # #<-factor->strg <Name> # # <Name> # It *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** I Gravel Trench Be-007 2 1 1 1 28 0 1 END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 26 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 1 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-TNFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC Al A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** 1 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** 1 1 0.01 0.0 0.0 0.5 0.0 END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> 1 0 4.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES FTABLE 1 92 5 Depth Area Volume Outflowl Outflow2 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.057392 0.000000 0,000000 0,000000 0.038889 0.057392 0.000893 0.000000 0.150463 0.077778 0.057392 0.001786 0.000000 0.150463 0.116667 0.057392 0.002678 0.000000 0.150463 0.155556 0.057392 0.003571 0.000000 0.150463 0.194444 0.057392 0.004464 0.000000 0.150463 0.233333 0.057392 0.005357 0.000000 0,150463 0.27222.2 0.057392 0.006249 0.000000 0.150463 0.311111 0.057392 0.007142 0.000000 0.150463 0.350000 0.057392 0.008035 0.000000 0.150463 0.388889 0.057392 0.008928 0.000000 0.150463 0.427778 0.057392 0.009820 0.000000 0.150463 0.466667 0.057392 0.010713 0,000000 0.150463 0.505556 0.057392 0.01.1606 0.000000 0.150463 0.544444 0.057392 0.012499 0.000000 0.150463 0.583333 0.057392 0.013391 0.000000 0.150463 0.622222 0.057392 0.01,4284 0.000000 0.150463 0.661111 0.057392 0.015177 0.000000 0.150463 0.700000 0.057392 0.016070 0.000000 0.150463 0.738889 0.057392 0,016963 0.000000 0.150463 0.777778 0.057392 0.017855 0.000000 0.150463 0.816667 0.057392 0.018748 0,000000 0.150463 0.855556 0.057392 0.019641 0.000000 0.150463 0.894444 0.057392 0.020534 0.000000 0.150463 0.933333 0.057392 0.021426 0.000000 0.150463 0.972222 0.057392 0.022319 0.000000 0.150463 1.011111 0.057392 0.023212 0.000000 0.150463 1.050000 0.057392 0.024105 0.000000 0.150463 1.088889 0.057392 0.024997 0.000000 0.150463 1.127778 0.057392 0.025890 0.000000 0.150463 1.166667 0,057392 0.026783 0.000000 0,150463 1.205556 0.057392 0.027676 0.000000 0.150463 Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 27 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 1.244444 0.057392 0.028569 0.000000 0.150463 1.283333 0.057392 0.029461 0.000000 0.150463 1.322222 0.057392 0.030354 0,000000 0,150463 1.361111 0.057392 0.031247 0.000000 0.150463 1.400000 0.057392 0.032140 0.000000 0.150463 1.438889 0.057392 0.033032 0,000000 0.150463 1.477778 0.057392 0.033925 0.000000 0.150463 1.516667 0.057392 0.034818 0.000000 0.150463 1.555556 0.057392 0.035711 0.000000 0,150463 1.594444 0.057392 0.036603 0.000000 0.150463 1.633333 0.057392 0.037496 0.000000 0.150463 1.672222 0.057392 0.038389 0.000000 0.150463 1.711111 0.057392 0.039282 0.000000 0.150463 1.750000 0.057392 0.040174 0.000000 0.150463 1.788889 0.057392 0.041067 0,000000 0.150463 1.827778 0.057392 0.041960 0.000000 0.150463 1.866667 0.057392 0.042853 0.000000 0.150463 1.905556 0.057392 0.043746 0.000000 0.150463 1.944444 0.057392 0.044638 0.000000 0.150463 1.983333 0.057392 0.045531 0.000000 0.150463 2.022222 0.057392 0.046424 0.000000 0.150463 2.061111 0.057392 0.047317 0.000000 0.150463 2.100000 0.057392 0.048209 0.000000 0.150463 2.138889 0.057392 0.049102 0,000000 0.150463 2.177778 0.057392 0.049995 0.000000 0.150463 2.216667 0.057392 0.050888 0.000000 0.150463 2.255556 0.057392 0.051780 0.000000 0.150463 2.294444 0.057392 0.052673 0.000000 0.150463 2.333333 0.057392 0.053566 0.000000 0.150463 2.372222 0.057392 0.054459 0.000000 0,150463 2.41.1111 0.057392 0.055351 0.000000 0.150463 2.450000 0.057392 0.056244 0.000000 0.150463 2.488889 0,057392 0.057137 0,000000 0.150463 2.527778 0.057392 0.058030 0.000000 0.150463 2.566667 0.057392 0.058923 0.000000 0.150463 2.605556 0.057392 0.059815 0.000000 0.150463 2.644444 0.057392 0.060708 0.000000 0.150463 2.683333 0.057392 0.061601 0.000000 0.150463 2.722222 0.057392 0.062494 0,000000 0,150463 2.761111 0.057392 0.063386 0.000000 0.150463 2.800000 0.057392 0.064279 0.000000 0.150463 2.838889 0.057392 0.065172 0.000000 0.150463 2.877778 0.057392 0.066065 0.000000 0.150463 2.916667 0.057392 0.066957 0.000000 0.150463 2.955556 0.057392 0.067850 0.000000 0,150463 2.994444 0.057392 0.068743 0.000000 0.150463 3.033333 0.057392 0.069636 0.064540 0.150463 3.072222 0.057392 0.070529 0.205391 0.150463 3.111111 0.057392 0.071421 0.389839 0.150463 3.150000 0.057392 0.072314 0.604786 0.150463 3.188889 0.057392 0.073207 0,838881 0.150463 3.227778 0.057392 0.074100 1 .080576 0.150463 3.266667 0.057392 0.074992 1.318080 0.150463 3.305556 0.057392 0.075885 1.540028 0.150463 3.344444 0.057392 0.076778 1..736538 0.150463 3.383333 0.057392 0.077671 1.900552 0.150463 3.422222 0.057392 0.078563 2.029388 0.150463 3.461111 0.057392 0,079456 2.126492 0.150463 3.500000 0.057392 0.080349 2.203335 0.150463 3.538889 0.057392 0.082581 2.312114 0.150463 END FTABLE 1 END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1.2 PERLND 1, 999 EXTNL PREC WDM 2 PREC ENGL 1.2 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGI. 0.76 IMPLND 1 999 EXTNL PETINP Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 28 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** RCHRES 1 HYDR RO 1 1 1 WDM 1.000 FLOW ENGL REPL RCHRES 1 HYDR O 1 1 1 WDM 1001 FLOW ENGL REPL RCHRES 1 HYDR O 2 1 1 WDM 1002 FLOW ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1003 STAG ENGL REPL COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 2 PERI.ND PWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 2 MASS-LINK 3 PERLND PWATER IFWO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 3 MASS-LINK 5 IMPLND IWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 5 MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 MASS-LINK 15 IMPLND IWATER SURO 0,083333 COPY INPUT MEAN END MASS-LINK 15 MASS-LINK 17 RCHRES OFLOW OVOL 1 COPY INPUT MEAN END MASS-LINK 17 END MASS-LINK END RUN Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 29 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Predeveloped HSPF Message File Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 30 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Mitigated HSPF Message File Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 31 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Disclaimer Legal Notice 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©by :Clear Creek Solutions, Inc. 2005-2024;All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia,WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com Flow Control Sub basin A 3/29/2024 3:23:57 PM Page 32 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington WWHM2012 PROJECT REPORT FLOW CONTROL SUB BASIN A PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington General Model Information WWHM2012 Project Name:Flow Control Sub basin B Site Name: Site Address: City: Report Date: 2/14/2024 Gage: Everett Data Start: 1948/10/01 Data End: 2009/09/30 Timestep: 15 Minute Precip Scale: 1.200 Version Date: 2023/01/27 Version: 4.2.19 POC Thresholds Low Flow Threshold for POC1: 50 Percent of the 2 Year High Flow Threshold for POC1: 50 Year Flow Control Sub basin B 2/14/2024 2:08:52 PM Page 2 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Landuse Basin Data Predeveloped Land Use Sub Basin B (Pre) Bypass: No Groundwater: No Pervious Land Use acre C, Forest, Flat 0.681 Pervious Total 0.681 Impervious Land Use acre Impervious Total 0 Basin Total 0.681 Flow Control Sub basin B 2/14/2024 2:08:52 PM Page 3 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Mitigated Land Use Basin 1 Bypass: No GroundWater: No Pervious Land Use acre C, Pasture, Flat 0.397 Pervious Total 0.397 Impervious Land Use acre ROADS FLAT 0.209 POND 0.075 Impervious Total 0.284 Basin Total 0.681 Flow Control Sub basin B 214 2024 2:08:52 PM Page 4 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Routing Elements Predeveloped Routing Flow Control Sub basin B 2/14/2024 2:08:52 PM Page 5 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Mitigated Routing Trapezoidal Pond 1 Bottom Length: 50.00 ft. Bottom Width: 20.00 ft. Depth: 4 ft. Volume at riser head: 0.1210 acre-feet. Infiltration On Infiltration rate: 1.5 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 84.942 Total Volume Through Riser(ac-ft.): 0.004 Total Volume Through Facility (ac-ft.): 84.946 Percent Infiltrated: 100 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Side slope 1: 3 To 1 Side slope 2: 3 To 1 Side slope 3: 3 To 1 Side slope 4: 3 To 1 Discharge Structure Riser Height: 3 ft. Riser Diameter: 12 in. Element Flows To: Outlet 1 Outlet 2 Pond Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.023 0.000 0.000 0.000 0.0444 0.023 0.001 0.000 0.034 0.0889 0.023 0.002 0.000 0.034 0.1333 0.024 0.003 0.000 0.034 0.1778 0.024 0.004 0.000 0.034 0.2222 0.025 0.005 0.000 0.034 0.2667 0.025 0.006 0.000 0.034 0.3111 0.026 0.007 0.000 0.034 0.3556 0.026 0.008 0.000 0.034 0.4000 0.026 0.010 0.000 0.034 0.4444 0.027 0.011 0.000 0.034 0.4889 0.027 0.012 0.000 0.034 0.5333 0.028 0.013 0.000 0.034 0.5778 0.028 0.014 0.000 0.034 0.6222 0.029 0.016 0.000 0.034 0.6667 0.029 0.017 0.000 0.034 0.7111 0.030 0.018 0.000 0.034 0.7556 0.030 0.020 0.000 0.034 0.8000 0.031 0.021 0.000 0.034 0.8444 0.031 0.023 0.000 0.034 0.8889 0.032 0.024 0.000 0.034 0.9333 0.032 0.025 0.000 0.034 0.9778 0.033 0.027 0.000 0.034 1.0222 0.033 0.028 0.000 0.034 1.0667 0.034 0.030 0.000 0.034 1.1111 0.034 0.031 0.000 0.034 1.1556 0.035 0.033 0.000 0.034 Flow Control Sub basin B 2/14/2024 2:08:52 PM Page 6 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 1.2000 0.035 0.035 0.000 0.034 1.2444 0.036 0.036 0.000 0.034 1.2889 0.036 0.038 0.000 0.034 1.3333 0.037 0.039 0.000 0.034 1.3778 0.037 0.041 0.000 0.034 1.4222 0.038 0.043 0.000 0.034 1.4667 0.038 0.044 0.000 0.034 1.5111 0.039 0.046 0.000 0.034 1.5556 0.040 0.048 0.000 0.034 1.6000 0.040 0.050 0.000 0.034 1.6444 0.041 0.052 0.000 0.034 1.6889 0.041 0.053 0.000 0.034 1.7333 0.042 0.055 0.000 0.034 1.7778 0.042 0.057 0.000 0.034 1.8222 0.043 0.059 0.000 0.034 1.8667 0.043 0.061 0.000 0.034 1.9111 0.044 0.063 0.000 0.034 1.9556 0.045 0.065 0.000 0.034 2.0000 0.045 0.067 0.000 0.034 2.0444 0.046 0.069 0.000 0.034 2.0889 0.046 0.071 0.000 0.034 2.1333 0.047 0.073 0.000 0.034 2.1778 0.047 0.075 0.000 0.034 2.2222 0.048 0.077 0.000 0.034 2.2667 0.049 0.080 0.000 0.034 2.3111 0.049 0.082 0.000 0.034 2.3556 0.050 0.084 0.000 0.034 2.4000 0.050 0.086 0.000 0.034 2.4444 0.051 0.088 0.000 0.034 2.4889 0.052 0.091 0.000 0.034 2.5333 0.052 0.093 0.000 0.034 2.5778 0.053 0.095 0.000 0.034 2.6222 0.053 0.098 0.000 0.034 2.6667 0.054 0.100 0.000 0.034 2.7111 0.055 0.103 0.000 0.034 2.7556 0.055 0.105 0.000 0.034 2.8000 0.056 0.108 0.000 0.034 2.8444 0.057 0.110 0.000 0.034 2.8889 0.057 0.113 0.000 0.034 2.9333 0.058 0.115 0.000 0.034 2.9778 0.059 0.118 0.000 0.034 3.0222 0.059 0.121 0.035 0.034 3.0667 0.060 0.123 0.182 0.034 3.1111 0.061 0.126 0.389 0.034 3.1556 0.061 0.129 0.637 0.034 3.2000 0.062 0.131 0.907 0.034 3.2444 0.062 0.134 1.183 0.034 3.2889 0.063 0.137 1.447 0.034 3.3333 0.064 0.140 1.683 0.034 3.3778 0.065 0.143 1.879 0.034 3.4222 0.065 0.146 2.029 0.034 3.4667 0.066 0.149 2.138 0.034 3.5111 0.067 0.152 2.251 0.034 3.5556 0.067 0.155 2.347 0.034 3.6000 0.068 0.158 2.439 0.034 3.6444 0.069 0.161 2.528 0.034 3.6889 0.069 0.164 2.614 0.034 3.7333 0.070 0.167 2.697 0.034 Flow Control Sub basin B 2/14/2024 2:08:52 PM Page 7 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 3.7778 0.071 0.170 2.777 0.034 3.8222 0.071 0.173 2.856 0.034 3.8667 0.072 0.176 2.932 0.034 3.9111 0.073 0.180 3.006 0.034 3.9556 0.074 0.183 3.078 0.034 4.0000 0.074 0.186 3.149 0.034 4.0444 0.075 0.189 3.218 0.034 Flow Control Sub basin B 2/14/2024 2:08:52 PM Page 8 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Analysis Results POC 1 ow 0 - IL omyo 1X5 IK4 IM2 IW2 lort 1 I' t1p Pere�nt Tm�Eao�ed.nv >-+ - 5 10 5 A u. b tl 3C Z M 9 Z6 ))w + Predeveloped x Mitigated Predeveloped Landuse Totals for POC#1 Total Pervious Area: 0.681 Total Impervious Area: 0 Mitigated Landuse Totals for POC#1 Total Pervious Area: 0.397 Total Impervious Area: 0.284 Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC#1 Return Period Flow(cfs) 2 year 0.022882 5 year 0.035101 10 year 0.044526 25 year 0.058009 50 year 0.069238 100 year 0.081519 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 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC#1 Year Predeveloped Mitigated 1949 0.023 0.000 1950 0.023 0.000 1951 0.021 0.000 1952 0.016 0.000 1953 0.014 0.000 1954 0.075 0.000 1955 0.029 0.000 1956 0.026 0.000 1957 0.032 0.000 1958 0.023 0.000 Flow Control Sub basin B 214 2024 2:08:52 PM Page 9 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 1959 0.023 0.000 1960 0.021 0.000 1961 0.041 0.000 1962 0.020 0.000 1963 0.033 0.000 1964 0.024 0.000 1965 0.020 0.000 1966 0.012 0.000 1967 0.024 0.000 1968 0.029 0.000 1969 0.070 0.000 1970 0.016 0.000 1971 0.026 0.000 1972 0.019 0.000 1973 0.018 0.000 1974 0.039 0.000 1975 0.016 0.000 1976 0.016 0.000 1977 0.014 0.000 1978 0.016 0.000 1979 0.046 0.000 1980 0.021 0.000 1981 0.017 0.000 1982 0.022 0.000 1983 0.037 0.000 1984 0.022 0.000 1985 0.027 0.000 1986 0.064 0.000 1987 0.030 0.000 1988 0.016 0.000 1989 0.016 0.000 1990 0.021 0.000 1991 0.022 0.000 1992 0.017 0.000 1993 0.014 0.000 1994 0.015 0.000 1995 0.022 0.000 1996 0.038 0.000 1997 0.076 0.018 1998 0.014 0.000 1999 0.018 0.000 2000 0.014 0.000 2001 0.005 0.000 2002 0.021 0.000 2003 0.016 0.000 2004 0.027 0.000 2005 0.019 0.000 2006 0.051 0.000 2007 0.040 0.000 2008 0.056 0.000 2009 0.017 0.000 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC#1 Rank Predeveloped Mitigated 1 0.0758 0.0184 2 0.0747 0.0000 3 0.0697 0.0000 Flow Control Sub basin B 214 2024 2:12:25 PM Page 10 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 4 0.0639 0.0000 5 0.0563 0.0000 6 0.0507 0.0000 7 0.0458 0.0000 8 0.0406 0.0000 9 0.0401 0.0000 10 0.0392 0.0000 11 0.0381 0.0000 12 0.0372 0.0000 13 0.0331 0.0000 14 0.0322 0.0000 15 0.0305 0.0000 16 0.0295 0.0000 17 0.0287 0.0000 18 0.0274 0.0000 19 0.0272 0.0000 20 0.0260 0.0000 21 0.0260 0.0000 22 0.0238 0.0000 23 0.0236 0.0000 24 0.0234 0.0000 25 0.0233 0.0000 26 0.0231 0.0000 27 0.0229 0.0000 28 0.0224 0.0000 29 0.0223 0.0000 30 0.0220 0.0000 31 0.0218 0.0000 32 0.0215 0.0000 33 0.0215 0.0000 34 0.0213 0.0000 35 0.0209 0.0000 36 0.0208 0.0000 37 0.0201 0.0000 38 0.0199 0.0000 39 0.0192 0.0000 40 0.0191 0.0000 41 0.0182 0.0000 42 0.0181 0.0000 43 0.0172 0.0000 44 0.0168 0.0000 45 0.0167 0.0000 46 0.0165 0.0000 47 0.0165 0.0000 48 0.0165 0.0000 49 0.0164 0.0000 50 0.0163 0.0000 51 0.0161 0.0000 52 0.0160 0.0000 53 0.0158 0.0000 54 0.0152 0.0000 55 0.0140 0.0000 56 0.0139 0.0000 57 0.0139 0.0000 58 0.0138 0.0000 59 0.0137 0.0000 60 0.0116 0.0000 61 0.0055 0.0000 Flow Control Sub basin B 214 2024 2:12:25 PM Page 11 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Flow Control Sub basin B 2/14/2024 2:12:25 PM Page 12 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Duration Flows The Facility PASSED Flow(cfs) Predev Mit Percentage Pass/Fail 0.0114 19601 7 0 Pass 0.0120 17002 7 0 Pass 0.0126 14690 7 0 Pass 0.0132 12731 5 0 Pass 0.0138 10934 5 0 Pass 0.0144 9437 5 0 Pass 0.0149 8173 4 0 Pass 0.0155 7084 4 0 Pass 0.0161 6126 4 0 Pass 0.0167 5315 3 0 Pass 0.0173 4661 3 0 Pass 0.0179 4066 1 0 Pass 0.0184 3555 0 0 Pass 0.0190 3136 0 0 Pass 0.0196 2761 0 0 Pass 0.0202 2449 0 0 Pass 0.0208 2145 0 0 Pass 0.0214 1894 0 0 Pass 0.0219 1657 0 0 Pass 0.0225 1508 0 0 Pass 0.0231 1370 0 0 Pass 0.0237 1249 0 0 Pass 0.0243 1154 0 0 Pass 0.0249 1071 0 0 Pass 0.0255 1009 0 0 Pass 0.0260 950 0 0 Pass 0.0266 888 0 0 Pass 0.0272 825 0 0 Pass 0.0278 777 0 0 Pass 0.0284 733 0 0 Pass 0.0290 687 0 0 Pass 0.0295 648 0 0 Pass 0.0301 622 0 0 Pass 0.0307 602 0 0 Pass 0.0313 583 0 0 Pass 0.0319 561 0 0 Pass 0.0325 538 0 0 Pass 0.0330 506 0 0 Pass 0.0336 487 0 0 Pass 0.0342 473 0 0 Pass 0.0348 457 0 0 Pass 0.0354 440 0 0 Pass 0.0360 424 0 0 Pass 0.0365 409 0 0 Pass 0.0371 394 0 0 Pass 0.0377 380 0 0 Pass 0.0383 368 0 0 Pass 0.0389 353 0 0 Pass 0.0395 341 0 0 Pass 0.0400 333 0 0 Pass 0.0406 322 0 0 Pass 0.0412 313 0 0 Pass 0.0418 303 0 0 Pass Flow Control Sub basin B 2.14 2024 2:12:25 PM Page 13 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 0.0424 293 0 0 Pass 0.0430 284 0 0 Pass 0.0436 276 0 0 Pass 0.0441 265 0 0 Pass 0.0447 257 0 0 Pass 0.0453 241 0 0 Pass 0.0459 234 0 0 Pass 0.0465 226 0 0 Pass 0.0471 212 0 0 Pass 0.0476 205 0 0 Pass 0.0482 195 0 0 Pass 0.0488 187 0 0 Pass 0.0494 177 0 0 Pass 0.0500 166 0 0 Pass 0.0506 160 0 0 Pass 0.0511 150 0 0 Pass 0.0517 146 0 0 Pass 0.0523 135 0 0 Pass 0.0529 128 0 0 Pass 0.0535 120 0 0 Pass 0.0541 111 0 0 Pass 0.0546 99 0 0 Pass 0.0552 85 0 0 Pass 0.0558 75 0 0 Pass 0.0564 63 0 0 Pass 0.0570 59 0 0 Pass 0.0576 56 0 0 Pass 0.0581 50 0 0 Pass 0.0587 42 0 0 Pass 0.0593 39 0 0 Pass 0.0599 37 0 0 Pass 0.0605 36 0 0 Pass 0.0611 30 0 0 Pass 0.0616 28 0 0 Pass 0.0622 26 0 0 Pass 0.0628 20 0 0 Pass 0.0634 16 0 0 Pass 0.0640 13 0 0 Pass 0.0646 8 0 0 Pass 0.0652 6 0 0 Pass 0.0657 5 0 0 Pass 0.0663 4 0 0 Pass 0.0669 4 0 0 Pass 0.0675 3 0 0 Pass 0.0681 3 0 0 Pass 0.0687 3 0 0 Pass 0.0692 3 0 0 Pass Flow Control Sub basin B 214 2024 2:12:25 PM Page 14 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Water Quality 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. Flow Control Sub basin B 2/14/2024 2:12:25 PM Page 15 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington LID Report LID Technique used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Comment Treatment') Needs Through Volume Volume Volume Water Quality Treatment Facility (ac-R) Infiltration Infiltrated Treated lac-try (ac-fi) Credd Trapezoidal Pond 1 POC Q 77.30 0 99.99 Total volume Infiltrated 7730 0-00 000 99.99 000 0%No Treat. Credit Compliance with LID Duration Standard 8%of 2-yr to 50%of Analysis 2 Result Passed Flow Control Sub basin B 214 2024 2:12:25 PM Page 16 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. Flow Control Sub basin B 214 2024 2:12:55 PM Page 17 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Appendix Predeveloped Schematic Sub Basin B (Pre) 0.68ac Flow Control Sub basin B 2/14/2024 2:12:55 PM Page 18 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Mitigated Schematic i Basin 1 0.68ac SI rapezoidal Pond 1 Flow Control Sub basin B 2/14/2024 2:12:56 PM Page 19 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 Flow Control Sub basin B.wdm MESSU 2.5 PreFlow Control Sub basin B.MES 27 PreFlow Control Sub basin B.L61 28 PreFlow Control Sub basin B.1,62 30 POCFlow Control Sub basin Bl.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 10 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE. DISPLY DISPLY-INFOl # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Sub Basin B (Pre) MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM It # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 10 C, Forest, Flat 1 1 1 1 27 0 END GEN-INFO *** Section. PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 10 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 10 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 20 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 10 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 10 0 4.5 0.08 400 0.05 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 10 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 10 0.2 0.5 0.35 6 0.5 0.7 END PWAT-PARM4 PWAT-STATEI <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 10 0 0 0 0 2.5 1 0 END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section. IWATER*** ACTIVITY <PLS > ************* Active Sections # - # ATMP SNOW TWAT SLD IWG IQAL *** END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW TWAT SLD IWG IQAL ********* END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 TWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END TWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATEI Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 21 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Sub Basin B (Pre)*** PERLND 10 0.681 COPY 501 12 PERLND 10 0.681 COPY 501 13 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 TNPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PINK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC Al A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1.2 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1.2 IMPLND 1 999 EXTNL PREC Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 22 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNT, PETTNP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY TNPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 END MASS-LINK END RUN Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 23 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Mitigated UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>** <-ID-> *** WDM 26 Flow Control Sub basin B.wdm MESSU 2.5 MitFlow Control Sub basin B.MES 27 MitFlow Control Sub basin B.L61 28 MitFlow Control Sub basin B.1,62 30 POCFlow Control Sub basin Bl.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 13 TMPI.ND 1 IMPLND 14 RCHRES 1 COPY 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INF01. # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Trapezoidal Pond 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERTES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-TNFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Ergl Metr *** in out *** 13 C, Pasture, Flat 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PI.S > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 13 0 0 1 0 0 0 0 0 0 0 0 0 END ACTTVTTY PRINT-INFO <PLS > ***************** Print-flags **"*******"*******"********** PIVL PYR Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 24 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC 13 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 13 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 13 0 4.5 0.06 400 0.05 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 13 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 13 0.15 0.4 0.3 6 0.5 0.4 END PWAT-PARM4 PWAT-STATEI <PLS > *** Initial conditions at start of simulation ran. from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 13 0 0 0 0 2.5 1 0 END PWAT-STATEI END PERLND IMPT.ND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 1 ROADS/FLAT 1 1 1 27 0 14 POND 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW TWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 14 0 0 1 0 0 0 END ACTIVTTY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 4 1 9 14 0 0 4 0 0 0 1 9 END PRINT-INFO TWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** ] 0 0 0 0 0 14 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 25 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 1 400 0.01 0.1 " . I 14 400 0.01 0.1 S.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 14 0 0 END IWAT-PARM3 IWAT-STATEI <PI.S > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 14 0 0 END IWAT-STATEI END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERI.ND 1.3 0.397 RCHRES 1 2 PERLND 13 0.397 RCHRES 1 3 IMPLND 1 0.209 RCHRES 1 5 IMPLND 14 0.075 RCHRES 1 5 ******Routing****** PERLND 13 0.397 COPY 1 12 IMPLND 1 0.209 COPY 1 15 IMPLND 14 0.075 COPY 1 15 PERLND 13 0.397 COPY 1 13 RCHRES 1 1 COPY 501 17 END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** 1 Trapezoidal Pond-007 2 1 1 1 28 0 1 END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1. 9 END PRINT-INFO HYDR-PARM1 Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 26 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington RCHRES Flags for each HYDR Section *** # - # VC Al A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit 1 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** 1 1 0.01 0.0 0.0 0.5 0.0 END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> 1 0 4.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES FTABLE 1 91 5 Depth Area Volume Outflowl Outflow2 Velocity Travel Time*** (ft) (acres) (acne-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.022957 0.000000 0.000000 0.000000 0.044444 0.023387 0.001030 0.000000 0,034722 0.088889 0.023820 0.002079 0.000000 0.034722 0.133333 0.024257 0.003147 0.000000 0.034722 0.177778 0,024697 0.004235 0,000000 0,034722 0.22222.2 0.025140 0.005343 0.000000 0.034722 0.266667 0.025587 0.006470 0.000000 0.034722 0.311111 0.026037 0.007617 0.000000 0.034722 0.355556 0.026490 0.008784 0.000000 0.034722 0.400000 0.026946 0.009972 0.000000 0.034722 0.444444 0.027405 0.011180 0,000000 0,034722 0.488889 0.027868 0.012408 0.000000 0.034722 0.533333 0.028334 0.013657 0.000000 0.034722 0.577778 0.028804 0.014927 0.000000 0.034722 0.622222 0.029276 0.01.6217 0.000000 0.034722 0.666667 0.029752 0.017529 0.000000 0.034722 0.711111 0.030231 0.018862 0.000000 0.034722 0.755556 0.030714 0.020216 0.000000 0.03472.2 0.800000 0.031199 0.021592 0.000000 0.034722 0.844444 0.031688 0.022990 0.000000 0.034722 0.888889 0.032180 0.02.4409 0.000000 0.034722 0.933333 0.032676 0.025850 0.000000 0.034722 0.977778 0.033175 0.027314 0,000000 0.034722 1.022222 0.033677 0.028799 0.000000 0.034722 1.066667 0.034182 0.030307 0.000000 0.034722 1.111111 0.034690 0.031838 0.000000 0.034722 1 .155556 0.035202 0.033391 0.000000 0.034722 1.200000 0.035717 0.034967 0.000000 0.034722 1.244444 0.036235 0.036566 0.000000 0.034722 1.288889 0.036757 0,038188 0.000000 0.034722 1.333333 0.037282 0.039833 0.000000 0.034722 1.377778 0.037810 0.041502 0,000000 0,034722 1 .422222. 0.038341 0.043194 0.000000 0.034722 1.466667 0.038876 0.044910 0.000000 0.034722 1.511111 0.039414 0.046650 0.000000 0.034722 1.555556 0.039955 0.048413 0.000000 0.034722 1.600000 0.040500 0.050201 0.000000 0.034722 1.644444 0.041047 0.052014 0.000000 0,034722 1.688889 0.041598 0.053850 0.000000 0.034722 1.733333 0.042152 0.055711 0.000000 0.034722 1.777778 0,042710 0.057597 0.000000 0.034722 1.822222 0.043271 0.059508 0.000000 0.034722 Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 27 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 1.866667 0.043835 0.061443 0.000000 0.034722 1.911111 0.044402 0.063404 0.000000 0.034722 1.955556 0.044973 0.065390 0,000000 0,034722 2.000000 0.045546 0.067402 0.000000 0.034722 2.044444 0.046123 0.069439 0.000000 0.034722 2.088889 0.046704 0.071502 0,000000 0.034722 2.133333 0.047287 0.073590 0.000000 0.034722 2.177778 0.047874 0.075705 0.000000 0.034722 2.222222 0.048464 0.077846 0.000000 0.034722 2.266667 0.049058 0.080013 0.000000 0.03472.2 2.311111 0.049655 0.082207 0.000000 0.034722 2.355556 0.050254 0.084427 0.000000 0.034722 2.400000 0.050858 0.086674 0.000000 0.034722 2.444444 0.051464 0.088948 0.000000 0.034722 2.488889 0.052074 0.091249 0,000000 0.034722 2.533333 0.052687 0.093577 0.000000 0.034722 2.577778 0.053303 0.095932 0.000000 0.034722 2.622222 0.053923 0.098315 0.000000 0.034722 2.666667 0.054545 0.100725 0.000000 0.034722 2.711111 0.055172 0.103163 0.000000 0.034722 2.755556 0.055801 0.105629 0.000000 0.034722 2.800000 0.056433 0.108123 0.000000 0.034722 2.844444 0.057069 0.110646 0.000000 0.034722 2.888889 0.057708 0,113196 0,000000 0,034722 2.933333 0.058351 0.115775 0.000000 0.034722 2.977778 0.058996 0.118383 0.000000 0.034722 3.022222 0.059645 0.121020 0.035147 0.034722 3.066667 0.060298 0.123685 0.182234 0.034722 3.111111 0.060953 0.126379 0.389839 0.034722 3.155556 0.061612 0.129103 0.637321 0,034722 3.200000 0.062274 0.131856 0.907676 0.034722 3.244444 0.062939 0,134639 1.183559 0.034722 3.288889 0,063607 0.137451 1,447495 0,034722 3.333333 0.064279 0.140293 1 .683468 0.034722 3.377778 0.064954 0.143165 1.879270 0.034722 3.422222 0.065632 0.146066 2.029388 0.034722 3.466667 0.066314 0.148999 2.138326 0.034722 3.511111 0.066999 0.151961 2.251735 0.034722 3.555556 0.067687 0,154954 2,347596 0,034722 3.600000 0.068378 0.157978 2.439693 0.034722 3.644444 0.069073 0.161032 2.528438 0.034722 3.688889 0.069771 0.164118 2.614172 0.034722 3.733333 0.070472 0.167234 2.6971.82 0.034722 3.777778 0.071176 0.170382 2.777713 0.034722 3.822222 0.071884 0.173561 2.855973 0.034722 3.866667 0.072595 0.176772 2.932146 0.03472.2 3.911111 0.073309 0.180014 3.006389 0.034722 3.955556 0.074027 0.183288 3.078843 0.034722 4.000000 0.074747 0.186594 3.149630 0.034722 END FTABLE 1 END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1.2 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1.2 IMPLND 1 999 EXTNL PREC WDM 1 EVAP F.NGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** RCHRES 1 HYDR RO 1 1 1 WDM 1000 FLOW ENGL REPL RCHRES 1. HYDR O 1. 1 1 WDM 1.002 FLOW ENGL REPI, RCHRES 1 HYDR O 2 1 1 WDM 1003 FLOW ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1001 STAG ENGL REPL COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 28 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPi. END EXT TARGETS MASS-LTNK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 2 PERLND PWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 2 MASS-LINK 3 PERLND PWATER IFWO 0.083333 RCHRES INFLOW IVOL END MASS-L.INK 3 MASS-LINK S TMPLND TWATER SURO 0.083333 RCHRES INFLOW TVOL END MASS-LINK 5 MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 MASS-LINK 15 IMPL.ND TWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 MASS-LINK 17 RCHRES OFLOW OVOL 1 COPY INPUT MEAN END MASS-LINK 17 END MASS-LINK END RUN Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 29 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Predeveloped HSPF Message File Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 30 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Mitigated HSPF Message File Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 31 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Disclaimer Legal Notice 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©by :Clear Creek Solutions, Inc. 2005-2024;All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia,WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com Flow Control Sub basin B 2/14/2024 2:12:58 PM Page 32 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Appendix C — Geotechnical Report PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GEOTECHNICAL ENGINEERING REPORT ARLINGTON COMMERCIAL DEVELOPMENT 7530 204T" STREET NE ARLINGTON, WASHINGTON ZGA Project No. 2760.01 March 28, 2024 Prepared for: WET RABBIT, LLC � r Prepared by: Zi pperGeo Geoprofessional Consultants 19019 36th Avenue W.,Suite E Lynnwood,WA 98036 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington ZipperGeo Geoprofessional Consultants ZGA Project No.2760.01 March 28,2024 Wet Rabbit,LLC 3213 West Wheeler Street,#750 Seattle,Washington 98199 Attention: Mr.Chris McClure Subject: Geotechnical Engineering Report Arlington Commercial Development 7530 204`h Street NE Arlington,Washington 98223 Parcel Numbers 310514-001-006-00 and 310514-001-010-00 Dear Mr.McClure, In accordance with your request and written authorization,Zipper Geo Associates,LLC(ZGA)has completed the subsurface evaluation and geotechnical engineering report for the above-referenced project. This report presents the findings of the subsurface evaluation and geotechnical recommendations for the project design and construction.Our services have been completed in general accordance with our Proposal for Geotechnical Services (Proposal No. P23120) dated September 22, 2023. Written authorization to proceed was provided by you on September 22,2023. We appreciate the opportunity to be of service to you on this project.If you have any questions concerning this report,or if we may be of further service,please contact us. Sincerely, Zipper Geo Associates,LLC of W aah/ ,p %QP ' 09 l ��oR WAS �—A a s t 0. 1763 y IR 3128124 e 38384 3128124 anaOd Geo�o o�� ;1S - ONAU JAMES P. OWRGIS James P.Georgis,L.E.G. Robert A.Ross,P.E. Principal Principal 19019 36`h Avenue West,Suite E Lynnwood,WA 98036 (425)582-9928 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington TABLE OF CONTENTS Page 1.0 INTRODUCTION.....................................................................................................................1 1.1 Site Description........................................................................................................................1 1.2 Project Understanding.............................................................................................................2 2.0 SUBSURFACE CONDITIONS.....................................................................................................2 2.1 Published Geologic Information..............................................................................................2 2.2 Soil Conditions.........................................................................................................................2 2.3 Groundwater Conditions.........................................................................................................3 3.0 CONCLUSIONS AND RECOMMENDATIONS..............................................................................4 3.1 General....................................................................................................................................4 3.2 Seismic Design Considerations................................................................................................5 3.3 Site Preparation.......................................................................................................................7 3.4 Structural Fill............................................................................................................................9 3.5 Utility Trenching and Backfilling............................................................................................11 3.6 Temporary Shoring................................................................................................................12 3.7 Temporary and Permanent Slopes........................................................................................12 3.8 Corrosion Considerations......................................................................................................13 3.9 Shallow Foundations..............................................................................................................13 3.10 On-Grade Concrete Floor Slabs.............................................................................................14 3.11 Mat Foundation Option.........................................................................................................15 3.12 Backfilled Walls......................................................................................................................17 3.13 Drainage Considerations........................................................................................................17 3.14 Infiltration Considerations.....................................................................................................18 3.15 Pavements.............................................................................................................................20 4.0 CLOSURE..............................................................................................................................21 FIGURES Figure 1—Site and Exploration Plan APPENDICES Appendix A—Subsurface Exploration Procedures and Logs Appendix B—Laboratory Testing Procedures and Results PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GEOTECHNICAL ENGINEERING REPORT ARLINGTON COMMERCIAL DEVELOPMENT 7530 204T"STREET NE ARLINGTON,WASHINGTON Project No.2760.01 March 28,2024 1.0 INTRODUCTION This report presents the surface and subsurface conditions encountered at the site and our geotechnical engineering recommendations for the proposed Arlington Commercial Development. Our scope of services included reviewing readily available geologic data,a site reconnaissance,subsurface evaluation, laboratory testing, geotechnical engineering analysis, and preparation of this report. The project description,site conditions,and our geotechnical conclusions and recommendations are presented in the text of this report. Supporting data including detailed exploration logs and field exploration procedures and the results of laboratory testing are presented as appendices. 1.1 Site Description The site is comprised of two adjoining Snohomish County tax parcels.Tax Parcel 310514-001-006-00 is a developed site with a property address of 7530 204`"Street NE in Arlington,Washington.According to Snohomish County Assessor's records,the developed parcel encompasses 0.86 acres of relatively level land with an unoccupied commercial building formerly occupied by Arlington Family Medicine located in the southeastern portion of the parcel. The building is a 3,520 square foot, one-story, wood-framed structure reportedly build in 1984.Asphalt surfaced drive lanes and parking are found to the north,west, and south of the commercial building.The development is services by underground utilities and includes a stormwater system. Vegetation includes ornamental plantings in parking lot islands and around the building,a row of large trees along the west and south property lines which appear to serve as a wind block,and a lawn south of the building.Asphalt pavements near the west and south rows of trees exhibit moderate root damage. Tax Parcel 310514-001-010-00 is a relatively level, undeveloped site located east of and adjoining the southern portion of the above discussed developed parcel's east property line.The parcel is irregular in shape and according to Snohomish County Assessor's records encompasses 0.81 acres. It appears that some underground utilities may be located near the east property line. Vegetation within the undeveloped parcel primarily consists of well-developed tall grasses with dense blackberry brush along its west and north property lines. A roughly"L"shaped drainage ditch is located along the northern portion of the developed parcels east property line and along the entire north property line of the undeveloped parcel.Running water of about 3 to 4 inches deep was observed in the drainage ditch during our site reconnaissance.The enclosed Site and Exploration Plan,Figure 1,includes an aerial photograph of the subject parcels. Page 1 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants 1.2 Project Understanding We understand that Wet Rabbit,LLC intends to redevelop the currently vacant developed parcel(310514- 001-006-00)with a new Wet Rabbit-branded car wash facility.We understand that redevelopment will generally include demolition of the existing structure,minor regrading,construction of a new drive-thru car wash tunnel in the west-central west side of the site,and reconfiguration and repaving of the parking lot and drive lanes.We understand that development of the currently undeveloped parcel(310514-001- 010-00) may include a one-story Quick Service Restaurant (QSR) or similar commercial development. Lightly loaded shallow foundations with slab-on-grade floors are anticipated. We understand that stormwater management design will be completed in accordance with the 2014 Washington State Department of Ecology (Ecology) Stormwater Management Manual for Western Washington(stormwater Manual).We understand that a below grade infiltration gallery is planned in the east-central portion of the western developed parcel with a bottom of facility elevation of about 122.5 feet.We understand that a stormwater infiltration pond is planned in the western portion of the eastern undeveloped parcel with a bottom of pond elevation of about 124 feet. 2.0 SUBSURFACE CONDITIONS 2.1 Published Geologic Information We assessed the geologic setting of site and the surrounding vicinity by reviewing the Geologic Map of the Arlington West Quadrangle,Snohomish County, Washington (US Geological Survey, Map MF-1740, 1985). The published geologic mapping shows the site is underlain by Vashon Recessional Outwash, Marysville Sand Member.The Marysville Sand Member is described as mostly well-drained,stratified to massive outwash sand, with some fine gravel, and some areas of silt and clay. The sediments were deposited by melt water flowing south from the stagnating and receding Vashon glacier.The outwash is reported to have a maximum thickness of about 140 feet. Subsurface conditions disclosed by the explorations advanced for this evaluation are consistent with the published mapping. 2.2 Soil Conditions The subsurface evaluation completed by ZGA for this project included four borings(B-1 through B-4)and one cone penetrometer test(CPT-01). CPT-01 was completed near the center of the proposed car wash development(currently developed western parcel)and extended to a depth of about 60 feet below grade. The CPT exploration included seismic shear wave velocity measurements. Borings B-1 and B-2 were completed in the north and south portions of the western parcel's existing parking lot,respectively,and extended about 36%feet below grade.Borings B-3 and B-4 were completed in the undeveloped eastern parcel and extended about 31Y2 to 36Y2 feet below grade.Groundwater monitoring wells were installed in borings B-1 through B-3 to evaluate changes in groundwater levels through the wet season. The enclosed Site and Exploration Plan, Figure 1, presents the approximate locations of our subsurface explorations completed for this project. Soil samples recovered from the borings were visually classified in general accordance with the Explanation of Exploration Logs enclosed in Appendix A. Detailed, descriptive logs of the subsurface explorations and the procedures utilized in the subsurface exploration program are also presented in Page 2 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants Appendix A.In general,our explorations disclosed asphalt pavement and topsoil over recessional glacial outwash deposits interpreted as the Marysville Sand Member.Generalized descriptions of subsurface soil conditions observed at the exploration locations are presented below. 2.2.1 Pavement Section Borings B-1 and B-2 were completed in the parking lot of the western parcel and encountered about 2 inches of asphalt.The thickness of the pavement at the CPT location could not be accurately determined due to the small diameter of the conical probe used to complete the exploration. 2.2.2 Topsoil Borings B-3 and B-4 were completed in the undeveloped eastern parcel and encountered about 3 to 4 inches of topsoil.In general,the topsoil consisted of loose,brown sand with silt and abundant fine roots. 2.2.3 Glacial Recessional Outwash Soil interpreted as glacial recessional outwash deposits of the Marysville Sand Member were encountered below the pavement in the western parcel and below the topsoil in the eastern undeveloped parcel.The glacial outwash deposits extended to the maximum depth explored of 36Y2 feet in the borings and 60 feet in the CPT. In general,the upper 5 to 7Y2 feet of the outwash consists of loose to medium dense sand with variable silt and silt with variable sand content.Soil mottling was observed in some of the samples collected in this depth range. From about 5 to 7Y2 feet down to about 15 to 17Y2 feet,the outwash generally consists of medium dense to very dense gravelly sand to sandy gravel with trace to some silt.From about 15 to 17% feet to the maximum depth explored at 60 feet below grade,the outwash generally consists of loose to medium dense sand with trace to some silt. 2.3 Groundwater Conditions Groundwater was observed in borings B-1 through B-3 about 25 to 30 feet below grade at the time of drilling. Groundwater monitoring wells were installed in borings B-1 through B-3. Groundwater monitoring well readings are typically more accurate than groundwater depth estimates completed at the time of drilling and are presented in the table below. Groundwater Monitoring Well Data Boring Approx.Surface Date of Groundwater Approx.Depth to Approx.Groundwater Number Elevation(ft) Measurement Groundwater(ft) Elevation(ft) 10/17/23 25.41 102.21 10/19/23 25.81 101.81 11/13/23 25.23 102.39 B-1 127.62 12/19/23 24.73 1 102.89 01/24/24 12.98 114.64 02/16/24 11.91 115.71 03/26/24 10.64 116.98 Page 3 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants Groundwater Monitoring Well Data Boring Approx.Surface Date of Groundwater Approx.Depth to Approx.Groundwater Number Elevation(ft) Measurement Groundwater(ft) Elevation(ft) 10/17/23 27.37 102.42 10/19/23 27.18 102.61 11/13/23 27.41 102.38 B-2 129.711 12/19/23 23.91 105.88 01/24/24 16.50 113.29 02/16/24 14.41 115.38 03/26/24 13.37 116A2 10/17/23 28.62 103.38 10/19/23 28.83 103.17 11/13/23 28.65 103.35 B-3 132 00 12/19/23 24.70 107.30 01/24/24 17.05 114.95 02/16/24 15.61 116.39 03/26/24 14.75 117.25 Ground surface elevations at the exploration locations are based on survey data provided by PacLand. Groundwater levels,flow rates and soil moisture conditions should be expected to vary throughout the year.Fluctuations of the groundwater levels will likely occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the explorations were performed.Therefore, groundwater levels during construction or at other times in the life of the development should be expected to vary. 3.0 CONCLUSIONS AND RECOMMENDATIONS 3.1 General Based on the results of our subsurface explorations, laboratory testing, and geotechnical engineering analyses, we conclude that the proposed development is feasible from a geotechnical standpoint, contingent on proper design and construction practices.The explorations completed for our evaluation encountered soils susceptible to seismic induced liquefaction settlements.This condition requires special design considerations,as discussed below. The liquefaction potential of the development was evaluated in accordance with the 2018 International Building Code(IBC). Based on our analysis,we estimate total seismic settlements of approximately 3 to 3%= inches could occur during the design earthquake. We estimate differential seismic settlements of approximately 1%to 1%z inches over a horizontal distance of 40 feet. In our experience,these levels of total and differential seismic settlement are typically considered expectable for most structures from a collapse prevention perspective,but should be evaluated by the owner relative to risk management and the project structural engineer relative to 2018 IBC design requirements and the specific building design being considered. If these levels of potential seismic settlement are not considered acceptable for conventional spread footings,we recommend that a mat foundation be considered.Due to the presence Page 4 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants of about 10 to 15 feet of dense to very dense gravelly soils above the potential zone of liquefaction,ground improvement methods,such as stone columns,are not recommended for liquefaction mitigation at this site.This report includes geotechnical design recommendations for both conventional spread and mat foundation options. Geotechnical engineering recommendations for foundation systems and other earthwork related phases of the project are outlined below. The recommendations contained in this report are based upon the results of field and laboratory testing(which are presented in Appendices A and B),engineering analyses, and our current understanding of the proposed project. ASTM and Washington State Department of Transportation (WSDOT) specification codes cited herein respectively refer to the current manual published by the American Society for Testing & Materials and the current edition of the Standard Specifications for Road,Bridge,and Municipal Construction,(M41-10). 3.2 Seismic Design Considerations The seismic performance of the proposed development was evaluated relative to seismic hazards resulting from ground shaking associated with a design seismic event with a 2,475-year return period determined in accordance with the 2018 International Building Code(IBC).Conformance to the above criteria for seismic excitation does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur if a maximum level earthquake occurs.The primary goal of the IBC seismic design procedure is to protect life and not to avoid all damage,since such design may be economically prohibitive. Following a major earthquake,a building may be damaged beyond repair, yet not collapse. 3.2.1 Ground Fault Rupture Based on review of the United States Geological Survey Quaternary Fault and Fold Database of the United States there are no mapped Quaternary faults within 10 miles of the site.It is our opinion that the risk of ground surface rupture at the site is low. 3.2.2 Landsliding Based on the relatively level topography of the site and surrounding vicinity,it is our opinion that the risk of earthquake-induced landsliding is low. 3.2.3 Liquefaction Liquefaction is a phenomenon wherein saturated cohesionless soils build up excess pore water pressures during earthquake loading. Liquefaction typically occurs in loose soils,but may occur in denser soils if the ground shaking is sufficiently strong. ZGA completed a liquefaction analysis in general accordance with the 2018 IBC and ASCE 7-16. Specifically,our analysis used the following primary seismic ground motion parameters. • A Maximum Considered Earthquake Geometric Mean (MCEG) Peak Ground Acceleration of 0.441g,based on Figure 22-9 of ASCE 7-16. Page 5 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants • A Modified Peak Ground Acceleration(PGQ of 0.511g based on Site Class D,per Section 11.8.3 of ASCE 7-16(Site Class modification to MCEG without regard to liquefaction in accordance with Sections 11.4.8 and 20.3.1 of ASCE 7-16). • A Geometric Mean Magnitude of 6.8 based on 2014 USGS National Seismic Hazard Mapping Project deaggregation data for a seismic event with a 2%probability of exceedance in 50 years (2,475 year return period). Our liquefaction analysis was completed using the computer program CLiq(Version 3.5.2.10)developed by GeoLogismiki.Our analysis was based on CPT-1 completed to a depth of about 60 feet below existing grade.The approximate exploration location is shown on the enclosed Site and Exploration Plans,Figure 1. Our analysis indicates the potential for liquefaction below the groundwater table,which was modeled at a median depth of 20 feet below grade in our analysis. 3.2.3.1 Liquefaction Settlement Based on our analyses, we estimate a total seismic settlement of approximately 3 to 3Y inches. We estimate a differential seismic settlement of approximately 1%to 1Y2 inches over a horizontal distance of 40 feet. If these levels of seismic induced liquefaction settlement are not acceptable for conventional spread footings,we recommend that a mat foundation be considered as discussed in subsequent sections of this report. 3.2.3.2 Lateral Spread Lateral spreading is a phenomenon in which soil deposits which underlie a site can experience significant lateral displacements associated with the reduction in soil strength caused by soil liquefaction. This phenomenon tends to occur most commonly at sites where the soil deposits can flow toward a "free- face",such as a water body. Given the relatively level nature of the site and lack of a free-face condition, it is our opinion that the potential for distress at the site from lateral spreading is low. 3.2.4 IBC Seismic Design Parameters Per the 2018 IBC seismic design procedures and ASCE 7-16,the presence of liquefiable soils requires a Site Class definition of F. However,through reference to Sections 11.4.8 and 20.3.1 of ASCE 7-16,the 2018 IBC allows site coefficients F, and F to be determined assuming that liquefaction does not occur for structures with fundamental periods of vibration less than 0.5 seconds. Based on the results of the field evaluation,Site Class D may be used to determine the values of Fa and F in accordance with Sections 11.4.8 and 20.3.1 of ASCE 7-16. If exceptions for Site Class D presented in Section 11.4.8 of ASCE 7-16 do not apply,a ground motion hazard analysis may be required. IBC Seismic Design Criteria Parameter Value 2018 International Building Code Site Classification(IBC)I Site Class F Z' Site Latitude/Longitude 48.1803/-122.1283 Spectral Short-Period Acceleration,Ss 1.038g Page 6 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants IBC Seismic Design Criteria Parameter Value Spectral 1-Second Acceleration,S1 0.371g Site Coefficient for a Short Period,FA 1.085 Site Coefficient for a 1-Second Period,Fv See ASCE Section 11.4.8 Spectral Acceleration for a 0.2-Second Period,Sens 1.126g Spectral Acceleration for a 1-Second Period,Sm, See ASCE Section 11.4.8 Design Short-Period Spectral Acceleration,SDs 0.751g Design 1-Second Spectral Acceleration,Soi See ASCE Section 11.4.8 1. IBC Site Class is based on the average characteristics of the upper 100 feet of the subsurface profile. 2. The explorations completed for this study extended to a maximum depth of about 60 feet below grade. ZGA therefore determined the Site Class assuming that medium dense to dense glacial outwash soils with an average n value greater than 15 extend to 100 feet as suggested by published geologic maps for the project area. 3. Per the 2018 International Building Code and ASCE 7-16,Chapter 20,any profile containing soils vulnerable to potential failure or collapse under seismic loading such as liquefiable soils. 3.3 Site Preparation 3.3.1 Existing Structure Removal The western parcel is currently developed with an unoccupied commercial building with associated asphalt pavement and concrete flatwork. After the building is removed, we recommend that any remaining foundation elements or other below grade structures, if encountered, be demolished and removed from the proposed development areas. We recommend that the resulting excavation be backfilled with compacted structural fill. 3.3.2 Existing Utility Removal We recommend that all underground utilities within the prosed building pad be completely removed. Utility pipes outside the building envelope could be abandoned in place,provided they are fully grouted with controlled density fill (CDF) and the trench backfill is density tested to verify that it meets the compaction levels presented in the project specifications. Localized excavations made for removal of utilities or existing unsuitable trench backfill should be backfilled with structural fill as outlined in the following section of this report. 3.3.3 Erosion Control Measures Stripped surfaces and soil stockpiles are typically a source of runoff sediments. We recommend that silt fences,berms,and/or swales be installed around the downslope side of stripped areas and stockpiles in order to capture runoff water and sediment. If earthwork occurs during wet weather,we recommend that all stripped surfaces be covered with straw to reduce runoff erosion,whereas soil stockpiles should be protected with anchored plastic sheeting. Page 7 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants 3.3.4 Temporary Drainage Stripping,excavation,grading,and subgrade preparation should be performed in a manner and sequence that will provide drainage at all times and provide proper control of erosion. The upper 5 to 7'/:feet of the site soils have a moderate fines(silt and clay)content and are therefore susceptible to disturbance and erosion when wet.The site should be graded to prevent water from ponding in construction areas and/or flowing into and/or over excavations. Exposed grades should be crowned,sloped,and smooth- drum rolled at the end of each day to facilitate drainage if inclement weather is forecasted. Accumulated water must be removed from subgrades and work areas immediately and prior to performing further work in the area. Equipment access may be limited,and the amount of soil rendered unfit for use as structural fill may be greatly increased if drainage efforts are not accomplished in a timely manner. 3.3.5 Clearing and Stripping Vegetation in the western developed parcel includes ornamental plantings in parking lot islands and around the building,a row of large trees along the west and south property lines which appear to serve as a wind block,and a lawn south of the building.Asphalt pavements near the west and south rows of trees exhibit moderate root damage.We anticipate that clearing and stripping depths on the order of 6 to 12 inches may be required in landscaped areas.Deeper excavations may be needed to remove tree roots along the south and west sides of the site. Vegetation within the undeveloped eastern parcel primarily consists of well-developed tall grasses with dense blackberry brush along its west and north property lines.Based on borings B-3 and B-4,we anticipate topsoil stripping depths on the order of 4 to 6 inches in the eastern parcel.Any excavations that extend below finish grades should be backfilled with structural fill as outlined subsequently in this report. 3.3.6 Subgrade Preparation and Protection Once site preparation is complete, all areas that do not require over-excavation and are at design subgrade elevation or areas that will receive new structural fill should be compacted to a firm and unyielding condition,and to achieve the recommended compaction level within the upper 12 inches of exposed subgrade soil presented in Section 3.5.6 of this report. Some moisture conditioning of site soils may be required to achieve a moisture content appropriate for compaction. This is generally within±2 percent of the soil's optimum moisture content determined in accordance with ASTM D 1557 test procedure. Our laboratory testing indicates that,at the time our explorations were completed, in-situ moisture contents collected from the upper 5 feet of the site range from about S to 29 percent. As a result,we expect that moisture conditioning of site soils during construction will be required to achieve suitable moisture contents(plus or minus two percent of optimum)for compaction. Earthwork should be completed during drier periods of the year when soil moisture content can be controlled by aeration and drying if possible. If earthwork or construction activities take place during extended periods of wet weather, it will be difficult to achieve a firm, non-yielding surface and recommended compaction levels. In the event the exposed subgrade becomes unstable, yielding, or unable to be compacted due to high moisture conditions,we recommend that the materials be removed to a sufficient depth in order to develop stable subgrade soils that can be compacted to the minimum Page 8 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants recommended levels.The severity of construction problems will be dependent,in part,on the precautions that are taken by the contractor to protect the subgrade soils. Once compacted,subgrades should be evaluated through density testing and proof rolling with a loaded dump truck or heavy rubber-tired construction equipment weighing at least 20 tons to assess the subgrade adequacy and to detect soft and/or yielding soils. In the event that compaction fails to meet the specified criteria,the upper 12 inches of subgrade should be scarified,and moisture conditioned as necessary to obtain the specified compaction level. Those soils which are soft,yielding,or unable to be compacted to the specified criteria should be over-excavated and replaced with suitable material as recommended in the Structural Fill section of this report. To protect stable subgrades in the wet season,we recommend using crushed rock. The thickness of the protective layer should be determined at the time of construction and be based on the moisture condition of the soil and the amount of anticipated traffic. 3.3.7 Freezing Conditions If earthwork takes place during freezing conditions,all exposed subgrades should be allowed to thaw and then be compacted prior to placing subsequent lifts of structural fill or pouring foundations. Alternatively, the frozen material could be stripped from the subgrade to expose unfrozen soil prior to placing subsequent lifts of fill or foundation components. The frozen soil should not be reused as structural fill until allowed to thaw and adjusted to the proper moisture content,which may not be possible during winter months. 3.4 Structural Fill Structural fill includes any material placed below foundations,floor slabs,and pavement sections,within utility trenches,and behind retaining walls. Prior to the placement of structural fill,all surfaces to receive fill should be prepared as previously recommended in the Site Preparation section of this report. 3.4.1 Laboratory Testing Representative samples of on-site and imported soils to be used as structural fill should be submitted for laboratory testing at least four days in advance of its intended use and required density testing in order to complete the necessary Proctor tests. 3.4.2 Re-Use of Site Soils as Structural Fill It is our opinion that the soils encountered on the site are adequate for reuse as structural fill from a compositional standpoint provided it is placed and compacted in accordance with the recommendations presented in this report. Our laboratory testing indicates that, at the time our explorations were completed,in-situ moisture contents collected from the upper 5 feet of the site range from about 5 to 29 percent. As a result,we expect that some moisture conditioning during construction of site soils will be required to achieve suitable moisture contents(plus or minus two percent of optimum)for compaction. Drying of over-optimum moisture soils may be achieved by scarifying or windrowing surficial materials during extended periods of dry weather. If encountered, soils which are dry of optimum may be Page 9 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants moistened through the application of water and thorough blending to facilitate a uniform moisture distribution in the soil prior to compaction. We recommend that site soils used as structural fill have less than 4 percent organics by weight,have no woody debris greater than %-inch in diameter, and contain no other deleterious materials. We recommend that all pieces of organic material greater than%:-inch in diameter be picked out of the fill before it is placed and compacted. Deleterious debris includes waste building materials,organics,trash, and asphalt and,if encountered,it should be removed from the soil prior to its reuse as structural fill. 3.4.3 Imported Structural Fill If additional material is required for grading and fills,the appropriate type of imported structural fill will depend on the weather conditions. During extended periods of dry weather,we recommend imported fill meet the requirements of Common Borrow,Options 1 or 2 as specified in Section 9-03.14(3)of the 2023 Washington State Department of Transportation, Standard Specifications for Road, Bridge, and Municipal Construction(WSDOT Standard Specifications).The on-site soils would generally be classified as Common Borrow. During wet weather, higher-quality (lower fines content)structural fill might be required,as Common Borrow may contain sufficient fines to be moisture sensitive. During wet weather we recommend that imported structural fill meet the requirements of Gravel Borrow as specified in Section 9-03.14(1)of the 2023 WSDOT Standard Specifications. 3.4.4 Moisture Content The suitability of soil for use as structural fill will depend on the prevailing weather at the time of construction,the moisture content of the soil,and the fines content(that portion passing the U.S.No.200 sieve) of the soil. As the amount of fines increases, the soil becomes increasingly sensitive to small changes in moisture content. Soils containing more than about 5 percent fines(such as most of the on- site soils encountered in the upper 2 feet of the site)cannot be consistently compacted to the appropriate levels when the moisture content is more than approximately 2 percent above or below the optimum moisture content(per ASTM D1557). Optimum moisture content is that moisture content which results in the greatest compacted dry density with a specified compactive effort.The moisture content of fill at the time of placement should be within plus or minus 2 percent of optimum moisture content for compaction as determined by the ASTM D1557 test method. 3.4.5 Fill Placement We recommend that structural fill be placed in horizontal lifts not exceeding 8 inches in loose thickness and each lift of fill be compacted using compaction equipment suitable for the soil type and lift thickness to the minimum levels recommended below based on the maximum laboratory dry density as determined by the ASTM D1557 Modified Proctor Compaction Test. 3.4.6 Compaction Criteria Our recommendations for soil compaction are summarized in the following table. We recommend that a geotechnical engineer be present during grading so that an adequate number of density tests may be conducted as structural fill placement occurs. Page 10 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants RECOMMENDED SOIL COMPACTION LEVELS Location Minimum Percent Compaction* All fill below building floor slabs and foundations 95 Upper 2 feet of fill below exterior slabs and pavements 95 Pavement and exterior slab fill below two feet 92 Upper two feet of utility trench backfill 95 Utility trenches below two feet 92 Landscape areas 90 * ASTM D1557 Modified Proctor Maximum Dry Density 3.5 Utility Trenching and Backfilling We recommend that utility trenching conforms to all applicable federal,state,and local regulations,such as OSHA and WISHA,for open excavations. Trench excavation safety guidelines are presented in WAC Chapter 296-155 and WISHA RCW Chapter 49.17. 3.5.1 Trench Dewatering Groundwater was encountered in borings B-1 through B-3 at depths of about 25 to 30 feet below existing grade at the time of our evaluation.As such,significant construction dewatering associated with utility installations is not anticipated.However,some excavations for utilities and underground structures may encounter zones of perched groundwater that may develop above lower permeability layers in the site outwash soils.The amount of perched groundwater seepage that may be encountered in site excavations will likely be a function of the time of year,the size of the excavation,the excavation depth,and how long the excavation remains open. The type and extent of dewatering measures needed, if any, will be a function of the groundwater conditions at the time of construction.Temporary systems could include pumped sumps,wellpoints,or pumped wells. If dewatering becomes necessary,the appropriate type of dewatering system and means of water disposal should be determined by the contractor based on the conditions encountered. 3.5.2 Utility Subgrade Preparation We recommend that all utility subgrades be firm and unyielding and free of soils that are loose,disturbed, or pumping. Soils that pump or yield should be removed and replaced. All structural fill used to replace over-excavated soils should be compacted as recommended in the Structural Fill section of this report. 3.5.3 Bedding and Initial Backfill We recommend that a minimum of 4 inches of bedding material be placed above and below all utilities or in general accordance with the utility manufacturer's recommendations and local ordinances. We recommend that pipe bedding consist of Gravel Backfill for Pipe Zone Bedding as specified in Section 9- 03.12(3)of the 2023 WSDOT Standard Specifications. All trenches should be wide enough to allow for compaction around the haunches of the pipe,or material such as pea gravel should be used below the Page 11 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants spring line of the pipes to eliminate the need for mechanical compaction in this portion of the trenches. If water is encountered in the excavations,it should be removed prior to fill placement. 3.5.4 Trench Backfill Materials, placement and compaction of utility trench backfill should be in accordance with the recommendations presented in the Structural Fill section of this report. In our opinion,the initial lift thickness should not exceed 1 foot unless recommended by the manufacturer to protect utilities from damage by compacting equipment. Light,hand operated compaction equipment may be utilized directly above utilities if damage resulting from heavier compaction equipment is of concern. 3.6 Temporary Shoring We recommend that temporary shoring systems be used where excavations will be located adjacent to existing foundations,property lines, roadways or utilities,or where ground loss could damage existing facilities. A trench box is one type of support system which might be used. The zone between the trench box and the excavation face should be backfilled as necessary to limit ground movements. As an alternative,braced or unbraced shoring of various types could be considered. 3.7 Temporary and Permanent Slopes Temporary excavation slope stability is a function of many factors,including: • The presence and abundance of groundwater; • The type and density of the various soil strata; • The depth of cut; • Surcharge loadings adjacent to the excavation;and • The length of time the excavation remains open. It is exceedingly difficult under the variable circumstances to pre-establish a safe and"maintenance-free" temporary cut slope angle.For planning purposes,temporary cuts in loose soils on the order of 1.5H:1V and temporary cuts in medium dense to very dense soils on the order of 1H:1V could be considered.These planning level temporary cut slope inclinations assume a drained condition.Flatter slopes may be needed if groundwater seepage is present.However,it should be the responsibility of the contractor to maintain safe temporary slope configurations since the contractor is continuously at the job site,able to observe the nature and condition of the cut slopes,and able to monitor the subsurface materials and groundwater conditions encountered. Unsupported vertical slopes or cuts deeper than 4 feet are not recommended. The cuts should be adequately sloped, shored,or supported to prevent injury to personnel from local sloughing and spalling.The excavation should conform to applicable Federal,State,and Local regulations. According to Chapter 296-155 of the Washington Administrative Code(WAC),the contractor should make a determination of excavation side slopes based on classification of soils encountered at the time of excavation.Temporary cuts may need to be constructed at flatter angles based upon the soil moisture, soil density,and groundwater conditions at the time of construction. Adjustments to the slope angles should be determined by the contractor at that time. Page 12 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants We recommend that all permanent cut or fill slopes constructed in native or properly compacted fill soils be designed at a 2H:1V(Horizontal:Vertical)inclination or flatter. All permanent cut and fill slopes should be adequately protected from erosion both temporarily and permanently. 3.8 Corrosion Considerations Soils in the vicinity of the project site are considered to be very slightly corrosive to concrete and are not typically associated with high sulfate contents. As such, the relative degree of sulfate attack would be considered negligible and ASTM Type 1/II Portland cement is suitable for all concrete below and at grade. 3.9 Shallow Foundations Based on our analyses, it is geotechnically feasible to support the proposed buildings on conventional shallow footings provided that foundation subgrades are properly prepared. We anticipate that foundation subgrade soils will generally consist of loose to medium dense sand with variable silt content. Our analyses indicate the potential for liquefaction induced settlement due to ground vibrations associated with the 2018 IBC design seismic event with a return period of 2,475 years.The foundation recommendations presented below assume that the levels of potential seismic settlement presented in Seismic Design Considerations section of this report(total seismic settlement of approximately 3 to 336 inches and differential seismic settlement of approximately 1%to 1%z inches over a horizontal distance of 40 feet)are considered acceptable and meet the Life Safety and Collapse Performance objectives of the 2018 IBC. If these conditions and levels of seismic settlement are not acceptable for the planned building, we recommend that the mat foundation option presented in this report be utilized to mitigate potential seismic settlements. However, if a mat foundation is utilized for the building, the spread foundation recommendations presented below may be used for ancillary structures determined by the structural engineer and owner to be less sensitive to potential seismic settlements. 3.9.1 Foundation Subgrade Preparation We recommend that the subgrade exposed at the bottom of foundation excavations be compacted to a firm and non-yielding condition and to at least 95 percent of the modified Proctor maximum dry density determined in accordance with ASTM D 1557. If the exposed subgrade cannot be compacted to the required density,we recommend that it be removed to a depth of 12 inches and be replaced with WSDOT Standard Specification Section 9-03.9(3),Crushed Surfacing Base Course compacted to at least 95 percent of the modified Proctor maximum dry density. We recommend that the over-excavation extend outside the limits of the footings a distance equal to the depth of over-excavation. 3.9.2 Allowable Bearing Pressure Continuous and isolated column footings bearing on compacted glacial outwash or structural fill placed and compacted in accordance with this report may be designed for a maximum allowable, net,bearing capacity of 2,000 psf. A one-third increase of the bearing pressure may be used for short-term transient Page 13 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants loads such as wind and seismic forces. The above-recommended allowable bearing pressure includes a 3.0 factor of safety. 3.9.3 Shallow Foundation Depth and Width For frost protection,the bottom of all exterior footings should bear at least 18 inches below the lowest adjacent outside grade,whereas the bottoms of interior footings should bear at least 12 inches below the surrounding slab surface level. We recommend that all continuous wall and isolated column footings be at least 12 and 24 inches wide,respectively. 3.9.4 Lateral Resistance Resistance to lateral loads can be calculated assuming an allowable passive resistance of 300 pcf equivalent fluid pressure(triangular distribution)and an allowable base friction coefficient of 0.35.The allowable passive resistance and friction coefficient include a 1.5 factor of safety.We recommend that passive resistance be neglected in the upper 18 inches of embedment. 3.9.5 Estimated Settlement Assuming the foundation subgrade soils,and structural fill compaction are completed in accordance with recommendations presented herein,we estimate that total and differential static settlements will be less than 1 inch and%inch over 40 feet,respectively. 3.10 On-Grade Concrete Floor Slabs Our analyses indicate the potential for liquefaction induced settlement due to ground vibrations associated with the 2018 IBC design seismic event with a return period of 2,475 years. The on-grade concrete floor slab recommendations presented below assume that the levels of potential seismic settlement presented in Seismic Design Considerations section of this report(total seismic settlement of approximately 3 to 3Y2 inches and differential seismic settlement of approximately 1%to 1Y2 inches over a horizontal distance of 40 feet)are considered acceptable.If these levels of seismic settlement are not acceptable,we recommend that the mat foundation option presented in this report be utilized to mitigate potential seismic settlements. 3.10.1 Subgrade Preparation After excavation to subgrade elevation,the base of the excavation is frequently disturbed or altered due to utility excavations,construction traffic,desiccation,or rainfall. As a result,the slab-on-grade subgrade may become unsuitable for floor slab support.We recommend that the slab subgrade be compacted to a firm and non-yielding condition and to at least 95 percent of the modified Proctor maximum dry density determined in accordance with ASTM D 1557.At the time of slab base placement,the subgrade should be evaluated by ZGA to verify a firm and non-yielding condition and adequate compaction. 3.10.2 Slab Base To provide a capillary break and uniform slab bearing surface, we recommend the on-grade slabs be underlain by a 4-inch thick layer of compacted clean crushed rock.In our opinion,the WSDOT Standard Specifications for Road,Bridge,and Municipal Construction does not include a material well suited for this Page 14 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants application below slabs. As such, we recommend that the capillary break conform to the graduation requirements for Type 21 or 22 Crushed Gravel as presented in the 2023 City of Seattle Standard Specifications for Road, Bridge, and Municipal Construction, Section 9-03.14, Mineral Aggregate Chart. Alternative capillary break materials should be submitted to the geotechnical engineer for review and approval before use. 3.10.3 Vapor Barrier Where potential slab moisture is a concern or where moisture sensitive floor coverings are planned,we recommend using a 15-mil,puncture-resistant proprietary product such as Stego Wrap,or an approved equivalent that is classified as a Class A vapor retarder in accordance with ASTM E 1745. Overlap lengths and the appropriate tape used to seal the laps should be in accordance with the vapor retarder manufacturer's recommendations. When conditions warrant the use of a vapor retarder, the slab designer and slab contractor should refer to ACI 302 and ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder/barrier. 3.11 Mat Foundation Option Our analyses indicate the potential for liquefaction induced settlement due to ground vibrations associated with the IBC design seismic event with a return period of 2,475 years. As discussed in the Seismic Design Considerations section of this report, we estimate a total seismic settlement of approximately 3 to 3Y2 inches and a differential seismic settlement of approximately 1%to 1'/:inches over a horizontal distance of 40 feet for the 2018 IBC design earthquake.A mat foundation could be considered to mitigate this seismic settlement risk. Geotechnical recommendations for a mat foundation are presented below. 3.11.1 Subgrade Preparation After excavation to subgrade elevation,the base of the excavation is frequently disturbed or altered due to utility excavations, construction traffic,desiccation,or rainfall. As a result,the foundation subgrade may become unsuitable.We recommend that the upper foot of mat foundation subgrade be compacted to a firm and non-yielding condition and to at least 95 percent of the modified Proctor maximum dry density determined in accordance with ASTM D 1557.At the time of slab base placement,the subgrade should be evaluated by ZGA to verify a firm and non-yielding condition and adequate compaction. 3.11.2 Mat Foundation Base To provide a capillary break and uniform slab bearing surface, we recommend the on-grade slabs be underlain by a 6-inch thick layer of compacted clean crushed rock.In our opinion,the WSDOT Standard Specifications for Road,Bridge,and Municipal Construction does not include a material well suited for this application below slabs. As such, we recommend that the capillary break conform to the graduation requirements for Type 21 or 22 Crushed Gravel as presented in the 2023 City of Seattle Standard Specifications for Road, Bridge,and Municipal Construction,Section 9-03.14, Mineral Aggregate Chart. Alternative capillary break materials should be submitted to the geotechnical engineer for review and approval before use. Page 15 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants 3.11.3 Modulus of Subgrade Reaction For mat foundation design supported on 6 inches of compacted structural fill as described above,we recommend a vertical modulus of subgrade reaction of 200 pounds per cubic inch (pci) be used. This vertical modulus is for a 1-foot by 1-foot loaded area. 3.11.4 Allowable Bearing Pressure and Static Settlement The soil bearing capacities for mat foundations supported on granular soils are typically very large due to large foundation widths and are therefore typically controlled by allowable settlement. Based on a mat foundation width of about 40 feet,length of about 50 to 70 feet,and embedment depth of about 1.5 feet, we recommend an allowable,net soil bearing capacity of 3,000 psf to limit total static settlement to less than 1 inch and differential static settlement to less than Y22 inch. A one-third increase of the bearing pressure may be used for short-term transient loads such as wind and seismic forces. Based on previous projects utilizing a mat foundation to support a structure of this size,we anticipate that actual loads would be substantially less than the allowable load of 3,000 psf.As such,total and differential static settlements are anticipated to be small.Settlements would occur elastically as loads are applied. 3.11.5 Mat Foundation Depth For frost protection,we recommend that the bottom of the mat foundation around the perimeter of the building bear at least 18 inches below the adjacent outside grade. 3.11.6 Lateral Resistance Resistance to lateral loads can be calculated assuming an allowable passive resistance of 300 pcf equivalent fluid pressure(triangular distribution)and an allowable base friction coefficient of 0.35.The allowable passive resistance and friction coefficient include a 1.5 factor of safety.We recommend that passive resistance be neglected in the upper 18 inches of embedment. 3.11.7 Vapor Barrier Where potential slab moisture is a concern or where moisture sensitive floor coverings are planned,we recommend using a 15-mil,puncture-resistant proprietary product such as Stego Wrap,or an approved equivalent that is classified as a Class A vapor retarder in accordance with ASTM E 1745. Overlap lengths and the appropriate tape used to seal the laps should be in accordance with the vapor retarder manufacturer's recommendations. When conditions warrant the use of a vapor retarder, the slab designer and slab contractor should refer to ACI 302 and ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder/barrier. 3.11.8 Estimated Seismic Settlements As discussed in the Seismic Considerations section of this report,our analyses indicate the potential for liquefaction induced settlement during the 2018 IBC design earthquake. Based on our analyses, we estimate a total seismic settlement of the soils beneath the slab of approximately 2%2 to 3 inches and a differential seismic settlement of approximately 1%to 1Y22 inches over a horizontal distance of 40 feet. Page 16 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants 3.12 Backfilled Walls We anticipate that the development may include some backfilled,cast-in-place(CIP),concrete,building foundation and/or landscape retaining walls.For recommended bearing capacities and lateral resistance parameters,refer to Shallow Foundations(Section 3.9)of this report.Please refer to Section 3.13.3 of this report for wall drainage recommendations. Additional recommendations for CIP retaining walls are provided below. 3.12.1 Lateral Earth Pressures The lateral soil pressures acting on backfilled retaining walls will depend on the nature and density of the soil behind the wall,and the ability of the wall to yield in response to the earth loads. Yielding walls(i.e., walls that are free to translate or rotate)that are able to displace laterally at least 0.001H,where H is the height of the wall,may be designed for active earth pressures. Non-yielding walls(i.e.,walls that are not free to translate or rotate)should be designed for at-rest earth pressures. Non-yielding walls include walls that are braced to another wall or structure,and wall corners. For backfilled walls,assuming they are backfilled and drained in accordance with Section 3.12.3 of this report,we recommend that yielding walls supporting horizontal backfill be designed using an equivalent fluid density of 35 pcf(active earth pressure).Non-yielding walls should be designed using an equivalent fluid density of 55 pcf (at-rest earth pressure). Surcharge pressures due to sloping backfill, adjacent footings,vehicles,construction equipment,etc.must be added to these lateral earth pressure values. For traffic loads,we recommend using an equivalent two-foot soil surcharge of 250 psf.For retaining walls over 6 feet tall with level backfill conditions,we recommend that a uniformly distributed seismic pressure of 12H psf,where H is the height of the wall, be applied to the walls if required by code. The above equivalent fluid pressures are based on the assumption of no buildup of hydrostatic pressure behind the wall. If groundwater is allowed to saturate the backfill soils, hydrostatic pressures will act against a retaining wall. 3.13 Drainage Considerations 3.13.1 Surface Drainage Final site grades should be sloped to carry surface water away from buildings and other drainage-sensitive areas. Additionally,site grades should be designed such that concentrated runoff on softscape surfaces is avoided. Any surface runoff directed towards softscaped slopes should be collected at the top of the slope and routed to the bottom of the slope and discharged in a manner that prevents erosion. 3.13.2 Building Perimeter Foundation Drains and Wall Drains We recommend that the building be provided with a footing drain system to reduce the risk of future moisture problems.The footing drains should consist of a minimum 4-inch diameter,Schedule 40,rigid, perforated PVC pipe placed at the base of the heel of the footing with the perforations facing down. The pipe should be surrounded by a minimum of 6 inches of clean free-draining granular material conforming to 2023 WSDOT Standard Specification 9-03.12(4), Gravel Backfill for Drains.A non-woven filter fabric such as Mirafi 140N,or equivalent,should envelope the free-draining granular material.At appropriate Page 17 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants intervals such that water backup does not occur,the drainpipe should be connected to a tightline system leading to a suitable discharge.Cleanouts should be provided for future maintenance.The tightline system must be separate from the roof drain system. Roof drains should be connected to a separate solid wall PVC tightline system and routed to a suitable discharge location. 3.23.2 Backfilled Retaining Wall Drains Adequate drainage measures must be installed to collect and direct subsurface water away from subgrade walls.All backfilled walls should include a drainage aggregate zone extending 1X feet from the back of wall for the full height of the wall. The drainage aggregate should consist of material meeting the requirements of 2023 WSDOT 9-03.12(2)Gravel Backfill for Walls.A minimum 4-inch diameter,Schedule 40,rigid, perforated PVC pipe should be provided at the base of backfilled walls with the perforations facing down to collect and direct subsurface water to an appropriate discharge point.The pipe should be surrounded by a minimum of 6 inches of clean free-draining granular material conforming to 2023 WSDOT Standard Specification 9-03.12(4),Gravel Backfill for Drains. A non-woven filter fabric such as Mirafi 140N, or equivalent, should envelope the free-draining granular material. At appropriate intervals such that water backup does not occur,the drainpipe should be connected to a tightline system leading to a suitable discharge.Cleanouts should be provided for future maintenance. The tightline system must be separate from the roof drain system. 3.14 Infiltration Considerations We understand that stormwater management design will be completed in accordance with the 2014 Washington State Department of Ecology Stormwater Management Manual for Western Washington (2014 DOE Manual).We understand that a below grade infiltration gallery is planned in the east-central portion of the western developed parcel with a bottom of facility elevation of about 122.5 feet. We understand that a stormwater infiltration pond is planned in the western portion of the eastern undeveloped parcel with a bottom of pond elevation of about 124 feet. Based on the results of our subsurface exploration and analysis,shallow stormwater infiltration systems appear geotechnically feasible. The following sections provide geotechnical design recommendations regarding stormwater infiltration into the recessional glacial recessional outwash deposits encountered on site. 3.14.1 Design Infiltration Rates Soil conditions observed in the site explorations are consistent with normally consolidated glacial recessional outwash deposits of the Marysville Sand Member and generally consist of the following. • Loose to medium dense sand with variable silt and silt with variable sand content in the upper 5 to 7%feet.Soil mottling was observed in some of the samples collected in this depth range. • From about 5 to 7'%feet down to about 15 to 17%feet,the outwash generally consists of medium dense to very dense gravelly sand to sandy gravel with trace to some silt. • From about 15 to 17'/:feet to the maximum depth explored at 60 feet below grade,the outwash generally consists of loose to medium dense sand with trace to some silt. Page 18 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants Volume 3, Section 3.3.6 of the 2014 DOE Manual includes provisions for the determination of initial and design saturated hydraulic conductivities for receptor soils based on 1)Large-Scale Pilot Infiltration Tests,2) Small-Scale Pilot Infiltration Tests,and 3)by means of the Soil Grain Size Analyses Method. We completed our evaluation of the design infiltration rate using the Soil Grain Size Analysis Method based on test results of soil samples collected in ZGA's explorations.Grain size analysis test results are presented in Appendix 8 of this report. The Design Infiltration Rates presented in the table below include the following correction factors in accordance with Volume 3,Section 3.3.6 of the 2014 DOE Manual. • Site Variability and number of locations tested(CFv)=0.5 • Test Method(CFt)=0.4 • Degree of influent control to prevent siltation and bio-buildup(CFm)=0.9 Summary of Grain Size Analysis Tests Relative to Stormwater Infiltration Sample Initial(unfactored) Sample Design Infiltration Exploration Depth Soil Formation Saturated Hydraulic Number Rate'(in/hr) (ft) Conductivity(in/hr) B-1 S-3 7% Marysville Sand Member 20.2 3.6 B-1 S-4 10 Marysville Sand Member 37.1 6.7 B-1 S-5 10 Marysville Sand Member 19.3 3.5 B-2 S-2 5 Marysville Sand Member 3.8 0.7 B-2 S-3 7/ Marysville Sand Member 12.5 2.3 B-2 S-4 10 Marysville Sand Member 15.6 2.8 B-2 S-5 15 Marysville Sand Member 14.7 2.6 B-3 S-2 5 Marysville Sand Member 39.9 7.2 B-3 S-3 7/ Marysville Sand Member 2.0 0.4 B-3 S-4 10 Marysville Sand Member 4.4 0.8 B-3 S-5 15 Marysville Sand Member 4.5 0.8 B-4 S-2 5 Marysville Sand Member 11.9 2.2 B-4 S-3 71 Marysville Sand Member 8.3 1.5 B-4 S-5 15 Marysville Sand Member 28.4 5.1 1. Includes Correction Factors:CFv=O.S,CFt=0.4,and CFm=0.9 Based on our subsurface explorations,laboratory testing,and the calculated infiltration rates presented in the table above,we recommend a design infiltration rate of 2.6 inches per hour for a stormwater gallery located in the east-central portion of the western parcel with a bottom of gallery elevation of 122.5 feet. For an infiltration pond located in the western portion of the eastern parcel with a bottom of pond elevation of 124 feet,we recommend a design infiltration rate of 1.5 inches per hour.The design infiltration rate for the Page 19 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants pond may be increased to 2.6 inches per hour if the bottom of the pond is lowered to an elevation less than 120.5 feet. 3.14.2 Seasonal High Groundwater ZGA monitored groundwater levels on a roughly monthly basis in observation wells installed in borings B- 1 through B-3 between 17 October 2023 and 26 March 2024. Based on our measurements, we recommend a seasonal high groundwater elevation of 117.5 feet. 3.14.3 Infiltration System Overflow Considerations The design of infiltration system is based on a number of design parameters with variable uncertainties. Therefore, we recommend that infiltration systems include an overflow when permitted by code to reduce the potential for water in the system from rising above the top of the system storage aggregate or the bottom of the base course for the parking lot pavement section during periods of unusually high or intense precipitation. 3.14.4 Water Quality Treatment Characteristics of Receptor Soils Soil requirements for water quality treatment considerations are presented under Site Suitability Criteria (SSC)4 and 6 in Volume 3,Section 3.3.7 of the 2014 DOE Manual.Laboratory test results relative to water quality treatment characteristics are summarized below.Analytical laboratory test results are presented in Appendix 8 of this report. 3.14.4.1 Organic Content SSC-6 requires a minimum organic content of 1 percent for treatment facilities. Organic content tests completed on three samples collected from borings B-1,B-2,and B-4(at depths of about 5,7Y2,and 10 feet below grade) had organic contents ranging from 1.1 to 1.6 percent by weight with an average of about 1.4 percent by weight. 3.14.4.2 Cation Exchange Capacity SSC-6 requires a minimum Cation Exchange Capacity(CEC)of 5 milliequivalents/100grams dry soil for treatment facilities.CEC tests completed on three samples collected from borings B-1,B-2,and B-4(at depths of about 5, 7%:, and 10 feet below grade) had CEC values ranging from 5.8 to 6.5 mill ieq uiva lents/100grams dry soil with an average of about 6.2 milliequivalents/100grams dry soil. It should be noted that SSC-6 states that lower CEC(less than 5 milliequivalents/100grams dry soil)may be considered if it is based on a soil loading capacity determination for the target pollutants that is accepted by the local jurisdiction. 3.15 Pavements 3.15.1 Asphalt Pavements The following pavement sections represent our minimum recommendations for an average level of performance during a 20-year design life; therefore, an average level of maintenance will likely be required. A 20-year pavement life typically assumes that an overlay will be placed after about 12 years. Page 20 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants Thicker asphalt, base,and subbase courses would offer better long-term performance, but would cost more initially. Conversely,thinner courses would be more susceptible to"alligator"cracking and other failure modes. As such,pavement design can be considered a compromise between a high initial cost and low maintenance costs versus a low initial cost and higher maintenance costs. The native subgrade soils are anticipated to consist of a mixture of sand with varying portions of silt. Based on our experience with similar soils,we have estimated a California Bearing Ration (CBR)value of 15 percent for this project.No traffic loading was provided for this project. We have assumed relatively low traffic volumes. We recommend that the upper 12 inches of pavement subgrades be prepared in accordance with the recommendations presented in the Subgrade Preparation section of this report. We recommend that the crushed aggregate base course conform to Section 9-03.9(3) of the WSDOT Standard Specifications.All base material should be compacted to at least 95 percent of the maximum dry density determined in accordance with ASTM:D 1557. 3.15.1.1 Asphalt Pavement Recommendations For light duty pavements(parking stall areas),we recommend 2Y2 inches of asphalt concrete over 4 inches of crushed rock base course. For heavy duty pavements(main access roads,truck delivery routes,etc.), we recommend 3Y2 inches of asphalt concrete over 6 inches of crushed rock base course. We recommend that the asphalt concrete conform to Section 9-02.1(4)for PG 58-22 or PG 64-22, Performance Graded Asphalt Binder as presented in the 2022 WSDOT Standard Specifications. We also recommend that the gradation of the asphalt aggregate conform to the aggregate gradation control points for%-inch mixes as presented in Section 9-03.8(6),HMA Proportions of Materials. We recommend that asphalt be compacted to a minimum of 92 percent and a maximum of 96 percent of the theoretical maximum density. 3.15.2 Concrete Pavements Concrete pavement design recommendations are based on an assumed modulus of rupture of 600 psi and a minimum compressive strength of 4,000 psi for the concrete. For light duty pavements,we recommend 5 inches of concrete over 4 inches of crushed aggregate base. For heavy duty pavements,we recommend 6 inches of concrete over 4 inches of crushed aggregate base. We recommend that concrete pavements be lightly reinforced with 6x6-W2.OxW2.0 welded wire fabric or equivalent to control cracking and have relatively closely spaced control joints on the order of 10 to 12 feet. We recommend that contraction joints be cut before the development of tensile stresses in the concrete. We recommend that the contraction joints be cut to a minimum depth of one inch.We further recommend that loading dock and trash enclosure pavements be reinforced with#4 bars at 15 inches each direction. 4.0 CLOSURE The analysis and recommendations presented in this report are based, in part, on the explorations completed for this study. The number,location,and depth of the explorations were completed within the constraints of budget and site access so as to yield the information for our environmental scope and Page 21 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Arlington Commercial Development Zi pperGeo ZGA Project No.2760.01 March 28,2024 Geoprofewonal Consultants to formulate our geotechnical recommendations.Project plans were in the preliminary stage at the time this report was prepared. We therefore recommend that ZGA be provided an opportunity to review the final plans and specifications when they become available in order to assess that the recommendations and design considerations presented in this report have been properly interpreted and implemented into the project design. The performance of earthwork,structural fill,foundations,and pavements depend greatly on proper site preparation and construction procedures. We recommend that Zipper Geo Associates, LLC be retained to provide geotechnical engineering services during the earthwork-related construction phases of the project. If variations in subsurface conditions are observed at that time,a qualified geotechnical engineer could provide additional geotechnical recommendations to the contractor and design team in a timely manner as the project construction progresses. This report has been prepared for the exclusive use of Wet Rabbit, LLC, and their agents, for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties,either express or implied,are intended or made. Site safety and excavation support are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Zipper Geo Associates,LLC reviews the changes and either verifies or modifies the conclusions of this report in writing. Page 22 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington APPENDIX A SUBSURFACE EXPLORATION PROCEDURES AND LOGS PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington APPENDIX A SUBSURFACE EXPLORATION PROCEDURES AND LOGS Subsurface Exploration Description Our subsurface evaluation for this project included advancing four borings(B-1 through B-4)and one cone penetrometer test(CPT-1),completed in October 2023.The approximate locations of the explorations are presented on the Site and Exploration Plan,Figure 1.Exploration locations and ground surface elevations were provided to ZGA by Pacland based on a site-specific survey completed by Hamsen. Soil Borings The borings were advanced using a track-mounted drill rig operated by a local drilling company(Holocene Drill,Inc.)working under subcontract to ZGA. The borings were advanced using hollow stem auger drilling methods. A geologist from our firm continuously observed the borings,logged the subsurface conditions encountered, and obtained representative soil samples. All samples were stored in moisture-tight containers and transported to our laboratory for further evaluation and testing. Samples were obtained by means of the Standard Penetration Test at 2.5-to 5-foot intervals throughout the drilling operation. The Standard Penetration Test(ASTM D 1586) procedure consists of driving a standard 2-inch outside diameter steel split spoon sampler 18 inches into the soil with a 140-pound hammer free falling 30 inches. The number of blows required to drive the sampler through each 6-inch interval is recorded,and the total number of blows struck during the final 12 inches is recorded as the Standard Penetration Resistance,or "blow count"(N value). If a total of 50 blows are struck within any 6-inch interval,the driving was stopped, and the blow count is recorded as 50 blows for the actual penetration distance. The resulting Standard Penetration Resistance values indicate the relative density of granular soils and the relative consistency of cohesive soils. The enclosed boring logs describes the vertical sequence of soils and materials encountered in the borings, based primarily upon our field classifications. Where a soil contact was observed to be gradational,our logs indicate the average contact depth. Where a soil type changed between sample intervals,we inferred the contact depth. Our logs also graphically indicate the blow count,sample type,sample number,and approximate depth of each soil sample obtained from the borings. If groundwater was encountered,the approximate groundwater depth, and date of observation, are depicted on the logs. Groundwater monitoring well installations are also graphically indicated on the logs. Cone Penetrometer Test(CPT) One electric cone penetrometer probe was completed using a truck-mounted probe rig operated by an independent firm(In-Situ Engineering,Inc.)working under subcontract to ZGA. An engineer from our firm continuously observed the probes while electronic monitoring equipment in the probe rig automatically logged the subsurface conditions. After the probe was completed,the probe hole was backfilled with a bentonite slurry. Throughout the probing operation, soil and groundwater properties were measured at 5-centimeter depth intervals by means of the Cone Penetration Test(CPT) in general accordance with ASTM D3441. PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington This testing procedure involves pushing a standard 1.5-inch diameter steel cone penetrometer into the soil with hydraulic rams. A cone penetrometer consists of a conical tip,a cylindrical sleeve,and a pressure transducer. As the penetrometer is pushed downward,the tip resistance,sleeve friction,and porewater pressure are measured electronically and plotted as a function of depth. Through interpretation,the resulting graphs can reveal soil types and groundwater levels,as well as the relative density of granular soils and the relative consistency of cohesive soils.The CPT exploration completed for this project also included measurements of soil shear wave velocity. The enclosed CPT graph presents the vertical plots of several soil properties and groundwater pressures measured by the cone penetrometer at each probe location. These graphs also depict the Standard Penetration Resistance(Nro)corresponding to each test interval,based on published conversion charts. PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington EXPLANATION OF EXPLORATION LOGS SOIL DESCRIPTION: Soil descriptions presented on the borings logs are based on visual observations. Soil descriptions include density(coarse- grained soils)or consistency(fine-grained soils),moisture,color,major soil type,and grain size modifiers and should not be interpreted to suggest laboratory or field testing unless indicated on the logs. Soil descriptions include the following: Density/consistency,moisture,color,grain size modifier (adjective Implying 31-49 percent),major soil type(CAPITALIZED implying 50+percent),minor grain size modifier(some implying 6-12 percent,with implying 13-30 percent,and trace implying 0-5 percent),descriptive modifiers(i.e.roots,fill debris,cemented,etc.),and interpreted general geologic description. Descriptions may also include comments describing geologic properties such as dilatancy,toughness,structure,plasticity,and angularity of coarse-grained particles. Additional information regarding geologic properties is presented in the report text as applicable. DENSITY/CONSISTENCY: Soil density/consistency in borings is related to the blow count number in blows per foot using the sampling method indicated on the logs.Soil density/consistency in test pits is related to a"Field Test"as described below. Soil consistency in test pits or borings may be augmented by field Torvane or Packet Penetrometer testing. Coarse-Grained Soils Density SPT Field Test Descriptor #blowsi t Very Loose 0-4 f Easily penetrated with Y:-inch steel rod pushed by hand. Loose 5-10 Difficult to penetrate with h-Inch steel rod pushed by hand. . -._...-_._...._._..._._...- ...._. Medium 11-30 Easily y penetrated a foot with Minch steel rod driven with 5-lb hammer. ............................................................ . ..... ............................................................................................................................._................... Dense 31-50 Difficult to penetrate a foot with%-inch steel rod driven with 5-lb hammer. ........................ .-.___-._.. Very Dense >50 Penetrated only a few inches with%inch steel rod driven with 5-lb hammer. Fine-Grained Soils Torvane Pocket Penetrometer Consistency SPT Undrained Unconfined Field Test Descriptor (#blowslft) shear Compressive strength(tsf) Strength (tsf) VerySoft -1 <0.125 <0.25 Easily penetrates sev....... Y _. - - - - Soft 3 a 0.125-0.25 i 0 25-0.5 Easily penetrates one inch by thumb. _ -- .............. ........................................................................I................... Medium a1Bl 5 R 0.25-0.5 0.5-1.0 Penetrated over%in.................._._..............._...._.__._.....................__..._-_.._..__... .._.. SUff is 0.5-1.0 1.0-2.0 Indented by thumb but penetrated only with great effort: Very_Stiff i 16--30 1.0-2.0 2 0-4.0 Readily indented by thumbnail.— Hard r >30 >2.0 >4,0 Indented by thumbnail with difficuR effort. MOISTURE Descriptor Field Test Dry Absence of moisture,dusty,dry to the touch. .................................... .................._.. Damp Too low to achieve compaction .-..- ..._... -........_ .._ . ....-._ PP ......... _ Moist Appears near optimum moisture content for compaction Wet Too wet to achieve compaction Saturated Below the 9 roundwater table,visible free moisture MAJOR SOIL TYPE: Coarse-grained soils with over 50%of the material retained on the U.S.No.200 sieve. Coarse-grained soils Include boulders, cobbles,gravels and sands. Fine-grained soils with over 50%of the material passing the U.S.No.200 sieve. Fine-grained soils include silts and clays. GRAIN SIZE Descriptor Sieve Size Grain Size Boulder >12" >12" Cobble 3-12 3-12 -_.. Gravel 3"-#4 - 3'-0 19" __.__._...._ Sand >94-#200 <0.19"->0.0029" Silt/Clay Passing#200 <0.0029" GRAIN SIZE MODIFIERS Descriptor Approximate Percentage Trace 0-5 Some 6-12 ....._.....__..... ....._......._._.._-..: -------- - --------- With 13-30 -------------------------------------- (silty,clayey,sandy,gravelly) s 31-50 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Boring Location: See Site and Exploration Plan Drilling Company:Holocene Bore Hole Dia.:8-inch T Elevation, 127.62 Feel Drillina Method: Hollow Stem Auger Hammer Tvoe:AlltgmabC B-1 Date Drilled: 10/1212023 Drill Rig: Diedrich D-50 Logaed by KRN SOIL DESCRIPTION PENETRATION RESISTANCE(biowsltoop N EUJ A Standard Penetration Test c �+ nThe stratification lines represent the approximate boundaries a d a Hammer Weight and Drop: ID between S between soil types. The transition may be gradual. Refer to c 3 "Q � c F report text and appendices for additional information. ( ° ° 0 20 40 60 m 0 Approximately 2-inches of asphalt over moist,brown,SAND with gravel to gravelly SAND,trace silt.(Marysville Sand Member) Very loose,moist,brown and mottled gray,silty SAND to �� T tZ• - I 3 SILT,some sand.No odors,no staining,PID<1 ppmv. 11 5 Dense,moist,gray,mottled,SILT,some sand,some roots.No 12 T ts• 4d cec odors,no staining,PID<1 ppmv. 11 oRc Grades to SAND,some gravel. Dense,moist,brown to gray,gravelly SAND,some sift. s-3 I tr M GSA 10 1 Dense,moist,brown to gray,gravelly SAND,some silt.No odors,no staining,PID<t ppmv. se s GSA I 15 T Dense,moist,brown to golden brown,gravelly SAND,some 11 I s <3 GSA silt.No odors,no staining,PID<1 ppmv. 1 h 20 ..-'•.tea Medium dense,moist,golden brown,SAND,trace to some silt.No odors,no staining,PID<t ppmv. s$ tr =. H25 SAMPLE LEGEND GROUNDWATER LEGEND 0 q Fines(<0.075 mm) I2-inch O.D.split spoon sample 0 Clean Sand 0 %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonile Plastic Limit I--E) Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis 1 Groundwater level at Arlington,WA time of drilling(ATD)or 20OW=200 Wash Analysis i� on date of Dale: March 2024 Project No.: 2760,01 Consol.=Consolidation Test N measurement. Att.=Atterberq Limits ZipperGeo BORING B_� G-P,a+es:�onal Co�=�«<�r. LOG: 19019 36th Ave.W,Suite E Lynnwood,WA Page 1 of 2 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Boring Location: See Site and Exploration Plan Drilling Company:Holocene Bore Hole Dia.:8-inch Too Elevation, 127.62 Feel Drillina Method: Hollow Stem Auger Hammer Tvoe:AlltgmabC B-1 Date Drilled: 10/1212023 Drill Rig: Diedrich D-50 Logaed by KRN SOIL DESCRIPTION m PENETRATION RESISTANCE(biowsltoop N EUJ A Standard Penetration Test �+ The stratification lines represent the approximate boundaries a d a o S ID between soil t o g c � Hammer Weight and Drop: types. The transition may be gradual. Refer to a 3 report text and appendices for additional information. ( 2 —o ~ 0 0 20 40 60 m 25 S-7 18, ^" '6 Medium dense,saturated,golden brown,SAND,trace to `�' :;� some sift.No odors,no staining,PID<1 ppmv. — 30 Loose,saturated,golden brown,SAND,trace to some silt. Boring completed at approximately 31.5 feet.Groundwater 11 was encountered at approximately 25 feet below ground surface at time of drilling.Ecology Well Tag ID BPX 514. 35 40 45 50 SAMPLE LEGEND GROUNDWATER LEGEND 0 q Fines(<0.075 mm) I2-inch O.D.split spoon sample 0 Clean Sand 0 %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonile Plastic Limit I--E Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis 1 Groundwater level at Arlington,WA time of drilling(ATD)or 20OW=200 Wash Analysis i� on date of Dale: March 2024 Project No.: 2760,01 Consol.=Consolidation Test N measurement. Att.=Atterberq Limits ZipperGeo BORING B�1 G-P,a+es:�ona1Co�=.«<�r.. LOG: 19019 36th Ave.W,Suite E Lynnwood,WA Page 2 of 2 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Borma Location: See Site and Exploration Plan Drilling Company:Holocene Bore Hole Dia.:8-inch Too Elevation 129.79 Feel Drilling Method: Hollow Stem Auger Hammer Type:Automatic B-2 Date Drilled 1 0/1 212 0 2 3 Drill Rig: Diedrich D-50 Logged bv: KRN SOIL DESCRIPTION PENETRATION RESISTANCE(blowsrfomj d w r W ♦ Standard Penetration Test o aThe stratification lines represent the approximate boundaries z a m a Hammer Weight and Drop: V m 0 between soil types. The transition may be gradual. Refer to a Q 3 report text and appendices for additional information. U)= ° ° 0 0 20 40 60 m 0 Approximately 2-inches of asphalt over moist,brown SAND, with gravel to gravelly SAND,trace silt.(Marysville Sand Member) Loose,moist,dark brown,silty SAND to sandy SILT,some S 1 T 16 e fine roots.No odors,no staining,PID<1 ppmv. 11 Grades to brown,decreasing roots,trace fine gravel. 5 Medium dense.moist,brown.silty SAND,trace gravel,trace SY T 18„ 12 GSA roots.No odors,no staining,PID<1 ppmv. 11 Very dense,moist,light brown to brown,gravelly SAND,with csA silt.No odors,no staining,PID<1 ppmv. S 3 16„ 58 cec ORG 1 i) Very dense,moist.brown to dark brown,GRAVEL,with sand s-a T 78„ 63 GSA and silt.No odors,no staining,PID<1 ppmv. 11 15 Dense,moist,brown,GRAVEL,with sand and silt.No odors, s-s I 18„ 41 34 GSA no staining,PID<1 ppmv. 1 Medium dense,moist,golden brown,SAND with trace to s-6 :ome silt.No odors,no staining,PID 0 ppmv. 11 SAMPLE LEGEND GROUNDWATER LEGEND 0 %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand 0 %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Benlonite Plastic Limit 1--8 Liquid Limit N GrouUConcrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis Groundwater level at Arlington,WA time of drilling(ATD)or 20OW=200 Wash Analysis on date of Date: March 2024 Project No.: 2760,01 Consol.=Consolidation Test measurement. Att.=Atterberq Limits ZipperGeo BORING B_2 LOG: '9019 36th Ave.W,Suite E Lynnwood,WA Page 1 of 2 PACLAND Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Borma Location: See Site and Exploration Plan Drilling Company:Holocene Bore Hole Dia.:8-inch Too Elevation 129.79 Feel Drilling Method: Hollow Stem Auger Hammer Type:Automatic B-2 Date Drilled 1 0/1 212 0 2 3 Drill Rig: Diedrich D-50 Logged by_: KRN SOIL DESCRIPTION PENETRATION RESISTANCE(blowsrfooi) m w r W ♦ Standard Penetration Test o aThe stratification lines represent the approximate boundaries z a m Hammer Weight and Drop: V m between soil types. The transition may be gradual. Refer to a 2 3 m report text and appendices for additional information. fait= ° ° ~ 0 0 20 40 60 00 25 ::. Medium dense,wet to saturated,golden brown,SAND with =: trace to some silt.No odors,no staining,PID<1 ppmv. s-r 1e .y ++ 30 Medium dense,saturated,golden brown,SAND,trace to S-a T 18 .._ some silt.No odors,no staining,PID 0 ppmv. 11 z 35 Medium dense.saturated.golden brown,SAND,trace to S.9 T 1r some silt.No odors,no staining,PID<1 ppmv. 11 Boring completed at approximately 36.5 feet.Groundwater was encountered at approximately 30 feet below ground surface at time of drilling.Ecology Well Tag ID BPX 515. 40 45 r 50 SAMPLE LEGEND GROUNDWAIERLEGEND 0 %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand 0 %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Benlonite Plastic Limit 1--8 Liquid Limit N GrouUConcrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis Groundwater level at Arlington,WA time of drilling(ATD)or 20OW=200 Wash Analysis on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test measurement. Att.=Atterberq Limits ZipperGeo BORING B-2 C—P"1Pt,o— t... LOG: 19019 36th Ave.W,Suite E Lynnwood,WA Page 2 of 2 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Borma Location: See Site and Exploration Plan Drilling Company:Holocene Bore Hole Dia.:8-inch Too Elevation 132.00 Feel Drilling Method: Hollow Stem Auger Hammer Type:Automatic B-3 Date Drilled 1 0/1 212 0 2 3 Drill Rig: Diedrich D-50 Logged by_: KRN SOIL DESCRIPTION PENETRATION RESISTANCE(blowsrfooi) m w r W ♦ Standard Penetration Test o aThe stratification lines represent the approximate boundaries z a m Q Hammer Weight and Drop: V m between soil types. The transition may be gradual. Refer to n 3 m report text and appendices for additional information. rail= ° ° ~ 0 0 20 40 60 m 0 Grass over approximately 3 inches of moist,brown.SAND with sill,abundant grass roots.(Marysville Sand member) Loose,moist,brown,SAND with sill to silly SAND,some fine S 1 T 18„ 6 roots.No odors,no staining,PID<1 ppmv. 11 5 Medium dense.moist,dark brown,SAND with gravel,some 9-2 I 18„ 27 c&1 silt.No odors,no staining,PID<1 ppmv. Dense,moist to wet,brown,sandy SILT,trace gravel.No S 3 I e• ,aGSAodors,no staining,PID<1ppmv. 10 Dense,moist to wet,brown,silty SAND.with gravel.No odors, s-a T 12„ se csq no staining,PID<1 ppmv. 11 Grades to gravelly SAND,some silt. 15 Very dense,wet,brown,silty SAND some gravel.No odors, s-s I e b2 Gsn no staining,PID<i ppmv. 1 Very dense,wet,brown,SAND with silt,decreasing fines to s-s :ome silt.No odors,no staining,PID<1 ppmv. 11 77, SAMPLE LEGEND GROUNDWATER LEGEND 0 %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand 0 %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Benlonite Plastic Limit 1--8 Liquid Limit N GrouUConcrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis Groundwater level at Arlington,WA time of drilling(ATD)or 20OW=200 Wash Analysis on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test measurement. Att.=Atterberq Limits ZipperGeo BORING B-3 G—proless,nnal LOG: '9019 36th Ave.W,Suite E Lynnwood,WA Page 1 of 2 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Borma Location: See Site and Exploration Plan Drilling Company:Holocene Bore Hole Dia.:8-inch Too Elevation 132.00 Feel Drilling Method: Hollow Stem Auger Hammer Type:Automatic B-3 Date Drilled 1 0/1 212 0 2 3 Drill Rig: Diedrich D-50 Logged by_: KRN SOIL DESCRIPTION PENETRATION RESISTANCE(blowsrfooi) m w r W ♦ Standard Penetration Test o aThe stratification lines represent the approximate boundaries z a m Q Hammer Weight and Drop: V m between soil types. The transition may be gradual. Refer to n ; 3 m report text and appendices for additional information. ran= ° ° ~ 0 0 20 40 60 m 25 ::. Medium dense,wet.brown,SAND,trace to some silt.No =: odors,no staining,PID<1 ppmv. s-r 1e• 30 Medium dense,saturated.brown.SAND,trace to some silt. s-a T it..r— Zz No odors,no staining,PID<1 ppmv. 11 :_z: - 35 Medium dense,saturated,brown.SAND,trace to some silt. S.9 T 1W No odors,no staining,PID<1 ppmv. 11 Boring completed at approximately 36.5 feet.Groundwater was encountered at approximately 30 feet below ground surface at time of drilling.Ecology Well Tag ID BPX 516. 40 45 r 50 SAMPLE LEGEND GROUNOWAIERLEGEND 0 %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand 0 %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Benlonite Plastic Limit 1--8 Liquid Limit N GrouUConcrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis Groundwater level at Arlington,WA time of drilling(ATD)or 20OW=200 Wash Analysis on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test measurement. Att.=Atterberq,Limits ZipperGeo BORING B_3 �F��,"rPt,���., t... LOG: 19019 36th Ave.W,Suite E Lynnwood,WA Page 2 of 2 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Bonno Location: See Site and Exploration Plan Drilling Company:Holocene Bore Hole Dia.:8-inch Too Elevation 130.61 Feel Drilling Method: Hollow Stem Auger Hammer Type:Automatic B-4 Date Drilled 1 0/1 212 0 2 3 Drill Rig: Diedrich D-50 Logged by_: KRN SOIL DESCRIPTION PENETRATION RESISTANCE(blowsrfool) m w r W ♦ Standard Penetration Test o aThe stratification lines represent the approximate boundaries z a m Q Hammer Weight and Drop: V m between soil types. The transition may be gradual. Refer to n 3 m report text and appendices for additional information. rail= ° ° ~ 0 0 20 40 60 m 0 Grass over approximately 4 inches of moist,brown.SAND with sill,abundant roots.(Marysville Sand Member) Loose,moist,brown.SAND,with to some gravel,some sill, T 5 trace roots.No odors,no staining,PID<1 ppmv. L 5 Loose,moist,brown,SAND,with silt,trace gravel.No odors, s-2 I 18 10 GSA no staining.PID 0 ppmv. T1 Dense,moist,dark brown,silty SAND,trace gravel.No odors, s s I 18' 41 GSA no staining,PID<1 ppmv. 10 Dense,moist,light brown,gravelly SAND,some silt.No odors. csAsr I y' ar G c no staining.PID<7 ppmv. 1 oRG 15 Dense,moist,light brown,gravelly SAND to sandy GRAVEL. s-s I 12• 35 No odors,no staining,PID<1 ppmv, 1 Medium dense,moist,light brown.SAND with gravel,trace s-e T ,O 21 silt.No odors,no staining,PID<1 ppmv. 1 -11 SAMPLELEGEND GROUNDWAIERLEGFNU %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand 0 %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonite Plastic Limit 1--8 Liquid Limit N GrouUConcrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis Groundwater level at Arlington,WA time of drilling(ATD)or 20OW=200 Wash Analysis on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test measurement. Att.=Atterberq Limits ZipperGeo BORING B-4 G—nrolP.z,—i LOG: '9019 36th Ave.W,Suite E Lynnwood,WA Page 1 of 2 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Bonno Location: See Site and Exploration Plan Drilling Company:Holocene Bore Hole Dia.:8-inch Too Elevation 130.61 Feel Drilling Method: Hollow Stem Auger Hammer Type:Automatic B-4 Date Drilled 1 0/1 212 0 2 3 Drill Rig: Diedrich D-50 Logged by_: KRN SOIL DESCRIPTION PENETRATION RESISTANCE(blowsrfool) m w r W ♦ Standard Penetration Test o aThe stratification lines represent the approximate boundaries z a m Q Hammer Weight and Drop: V m d between soil types. The transition may be gradual. Refer to report text and appendices for additional information. ran= ° ° ~ 0 20 40 60 m 25 Medium dense.moist,light brown,SAND with gravel,trace silt.No odors,no staining,PID<1 ppmv, s r a 30 Medium dense.moist to wet,light brown.SAND with gravel. so T 12. trace silt.No odors,no staining,PID<1 ppmv. 11 Boring completed at approximately 31.5 feet.Groundwater was riot encountered at time of drilling.Borehole backfilled j with bentonite. I 35 j I i i I I 45 r 50 SAMPLE LEGEND GROUNDWATER LEGEND O %Fines(<0.075 mm) I2-inch O.D.split spoon sample Il Clean Sand 0 %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Benlonite Plastic Limit 1--8 Liquid Limit N GrouUConcrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis Groundwater level at Arlington,WA time of drilling(ATD)or 20OW=200 Wash Analysis on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test measurement. Att.=Atterberq Limits ZipperGeo BORING B-4 C—P"fPt,h— t... LOG: 19019 36th Ave.W,Suite E Lynnwood,WA Page 2 of 2 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington CPT-01 CPT CONTRACTOR:In Situ Engineering OPERATOR:Forinash CUSTOMER:Zippergeo CONE ID:DDG1369 LOCATION:Arlington TEST DATE:10/17/2023 9:30:24 AM JOB NUMBER:2760.01 PREDRILL:Oft BACKFILL:20%Slurry&Bentonite Chips SURFACE PATCH:Cold Patch Tip COR Sleeve Stress F.Ratio Pore Pressure SBT FR SPT (tsf) (tso M (psi) (RC 1983) (blows/ft) O o 600 0 9 0 9 -10 is 0 12 0 120 10 20 '7T f�t 30 Depth 40 50 60 70 TOTAL DEPTH:60.203 R 1 sensitive Fine grained 4 silty clay to clay 7 silly sand to sandy silt 10 gravelly sand to sand 2 organic material 5 clayey silt to silty clay 8 sand to silty sand 11 very stiff fine grained(') 3 clay 6 sandy silt to clayey silt 9 sand 12 sand to clayey sand(') 'SBT/SPT CORRELATION:UBC-1983 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington HOLE NUMBER:CPT-01 Depth 3.12f1 Arrival 7.27mS Ref* Velocity' I Depth 9.68ft Arrival 17.66mS Ref 3.1211 Velocity 577.77ft/S Depth 16.08ft I Arrival 22.97mS Ref 9.68ft Velocity 1181.03ft/S Depth 22.47ft I Arrival 28.59mS Ref 16.08ft Velocity 1127.77ft/S Depth 28.87ft Arrival 35.39mS Ref 22.47ft Velocity 936.85ft/S Depth 35.43ft Arrival42.42mS Ref 28.87ft Velocity 930.45ft/S Depth 41.83ft Arrival 49.14mS Ref 35.43ft Velocity 950.28fl/S Depth 48.39ft Arrival 55.43mS Ref41.83ft Velocity 1041.82ft/S Depth 54.79ft Arrival 61.17mS Ref 48.39ft Velocity 1112.91f/S Depth 60.20ft Arrival 66.05mS Ref 54.79ft Velocity 1107.69fVS 0 20 40 60 80 100 120 140 160 Time(mS) Hammer to Rod String Distance(ft):2.49 =Not Determined COMMENT: PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington APPENDIX B LABORATORY TESTING PROCEDURES AND RESULTS PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington LABORATORY TESTING PROCEDURES A series of laboratory tests were performed during the course of this study to evaluate the index and geotechnical engineering properties of the subsurface soils. Descriptions of the types of tests performed are given below. Visual Classification Samples recovered from the exploration locations were visually classified in the field during the exploration program. Representative portions of the samples were carefully packaged in moisture tight containers and transported to our laboratory where the field classifications were verified or modified as required. Visual classification was generally done in accordance with ASTM D2488. Visual soil classification includes evaluation of color,relative moisture content,soil type based upon grain size,and accessory soil types included in the sample. Soil classifications are presented on the exploration logs in Appendix A. Moisture Content Determinations Moisture content determinations were performed on representative samples obtained from the explorations to aid in identification and correlation of soil types. The determinations were made in general accordance with the test procedures described in ASTM D2216. Moisture contents are presented on the exploration logs in Appendix A. Grain Size Analysis A grain size analysis presents the range in diameter of soil particles that comprise a particular sample. Grain size analyses were performed on representative samples in general accordance with ASTM:D6913. The results of the grain size determinations for the samples were used in classification of the soils and are presented in this appendix. Cation Exchange Capacity Cation exchange capacity tests were completed on representative samples collected from prospective infiltration receptor soils by an independent analytical laboratory in accordance with the Washington State Department of Ecology SW-846 9081 test method.Test results are presented in this appendix. Organic Content Tests Organic content tests were completed on representative samples collected from prospective infiltration receptor soils by an independent analytical laboratory in accordance with ASTM D2974 test method.Test results are presented in this appendix. PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36' 12- 6' 3' 1 UY 314' ". 4 10 20 40 60 i,() 200 100 90 = 80 W 70 } to W 6U Z LL 50 Z w V W 40 a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS Coarse rme Coarse Medium Fine Silt Clay BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth feet Moisture(%) Fines % Description Gravelly SAND, B-1 S-3 7.5 5.6 10.1 some silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES US STANDARD SIEVE SIZE HYDROMFTER 36" 12' ti' 3• 1 112' 314" 318" 4 10 10 40 60 t40 200 100 90 = 80 W 70 m W 60 2 U- H 50 Z W U W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0 001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Silt Clay J BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture I%) Fines(%) I Description Gravelly SAND. B-1 S-4 10 6.8 7.9 some silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotecnnkal and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMFTER 36" 1P" 6' 3' 1112' w 31- a 10 20 60 60 140 200 100 90 = 80 uJ 70 m W 60 2 LL 50 Z W U W 40 W o_ 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0 001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Sip Clay J BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture(%) Fines(%) Description Gravelly SAND, B-1 S-5 15 6.1 9.1 some silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotecnnkal and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMFTER 36" 12' ti' 3' 1/12' 314" 318` 4 10 20 40 60 140 200 100 90 = 80 W 70 m W 60 2 LL H 50 Z W U W 40 W o_ 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0 001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Sip Clay J BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture(%) Fines(%) Description Silty SAND, B-2 S-2 5 16.3 48.1 trace grave PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotecnnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commerical Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES US STANDARD SIEVE SIZE HYDROMFTER 36" 12' ti' 3• 1"r 34" 318" 4 10 10 40 60 t40 200 100 90 = 80 2 W 70 m W 60 2 U- H 50 Z W U Of 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0 001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Silt Clay J BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture I%) Fines(%) I Description Gravelly SAND. B-2 S-3 7.5 6.2 17.5 with silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotecnnkal and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36' 12' 6' 3' 1112' 3l4' 3i6" 4 10 20 40 60 140 200 100 90 = 80 LU ?� 70 } m w 60 z LL 50 z w W 40 w a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0 001 PARTICLE SIZE IN MILLIMETERS JCoarse Fine Coarse Medium Fine Sill J BOULDERS COBBLES GRAVEL SAND FINE GRAWED Comments: Exploration Sample Depth (feet) Moisture(% Fines % Description GRAVEL,with B-2 S-4 10 5.2 15.3 sand and silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S STANDARD SIEVE SIZE HYDROMETER W IT 6' a' Iv" ern' 3.9' a 10 20 <0 60 140 200 100 90 = so W 70 } m W 6D Z LL 50 Z W V W 40 a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS Coarse F me t�,N—LL-dium rine Silt Clay BOULDERS COBBLES GRAVEL D FINE GRAINED Comments: Exploration Sample Depth feet Moisture %) Fines % Description GRAVEL.with B-2 S-5 15 5.1 13.3 sand and silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC G�te hnicaf and ErnironmentA Con-lt.antS DATE OF TESTING: 10/16/2023 Arlington Commercial Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMFTER 36" 1P" 6' 3' 1 112' 314" 37a' < 10 20 60 60 140 200 100 90 = 80 uJ 70 m W 60 2 LL H 50 Z uJ U of 40 uJ o_ 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0 001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Sip Clay J BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture(%) Fines(%) Description SAND,with B-3 S-2 5 5.4 6.8 gravel,some silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotecnnkat and Environmentat Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12, 6 3' 11R' 314- &8" 4 10 10 411 60 140 200 100 90 = 80 W 70 m W 60 2 LL H 50 Z Lu U Of 40 UJ a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0 001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Shc Ca'; J BOULDERS COBBLES GRAVEL SAND FME GRAINED Comments: Exoloration Sample Depth (feet) Moisture % Fines(%) Description Sandy SILT, B-3 S-3 7.5 26.1 61.4 trace gravel PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotechnical and Environmental consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES US STANDARD SIEVE SIZE HYDROMETER 36" 12' 6' 3' 1 11r W W 4 10 20 40 6D 140 200 100 90 = 80 Lu ?� 70 } m w 60 z LL 50 z w W 40 w a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0 001 PARTICLE SIZE IN MILLIMETERS Coarse Fine P.1. edwm Fine 9dlClay BOULDERS COBBLES GRAVEL FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture % Fines(%) Description B-3 S-4 10 17.6 35.9 Silty SAND,with gravel PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotechnical and Environmental consultan!s DATE OF TESTING: 10/16/2023 Arlington Commercial Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES US STANDARD SIEVE SIZE HYDROMFTER 36" 12' ti' 3- 1 1rP 34- 3+6' a 10 21 40 60 140 200 100 go = 80 uJ 70 m W 60 2 LL 50 Z W U Of 40 W o_ 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0 001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Sip Clay J BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture(%) Fines m Description Silty SAND, B-3 S-5 15 21.4 43.5 some gravel PROJECT NO:2760.01 PROJECT NAME, Zipper Geo Associates,LLC Geotecnnkal and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commerical Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES US STANDARD SIEVE SIZE HYDROMFTER 36" tY t' 3- 1lir 34" 316' 4 10 A) 40 6r, t40 200 100 90 = 80 W 70 m W 60 2 LL H 50 Z W U W 40 W a 30 20 10 0 iLiHIL 1000.000 100.000 10.000 1.000 0.100 0.010 0 001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medtum Fine Silt Clay J BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture I%) Fines(%) I Description SAND,with silt, B-4 S-2 5 14.7 23.8 trace gravel PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotecnnkal and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES US STANDARD SIEVE SIZE HYDROMFTER 36" 12' ti' 3- 1 11T TV 3+6' 4 10 20 40 60 140 200 100 90 = 80 W 70 m W 60 2 LL H 50 Z W U W 40 W o_ 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0 001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Sip clay J BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture(%) Fines(%) Description Silty SAND, B-4 S-3 7.5 18.5 30.6 trace gravel PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotecnnkal and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12, 6 3' 11/2' 3!e" 3W a 10 10 40 60 140 200 100 90 = 80 W 70 m W 60 2 LL H 50 Z W U W 40 IL a 30 20 10 im 0 1000.000 100.000 10.000 1.000 0.100 0.010 0 001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Shc Ca'; J BOULDERS COBBLES GRAVEL SAND FME GRAINED Comments: Exoloration Sample Depth (feet) Moisture % Fines(%) Description Gravelly SAND, B-4 S-5 15 6.1 7.4 some silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotechnical and Environmental consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington AMEST Am Test Inc. L A e o R A T o A I E s Professional 13600 NE 126TH PL Analytical Suite C Services Kirkland,WA 98034 (425)885-1664 Oct 25 2023 ZIPPER GEO ASSOCIATES,LLC 19019 36TH AVENUE W SUITE E LYNNWOOD,WA 98036 Attention: JAMES GEORGIS Dear JAMES GEORGIS: Enclosed please find the analytical data for your ARLINGTON COMMERCIAL DEVELOPMENT project. The following is a cross correlation of client and laboratory identifications for your convenience. CLIENT ID MATRIX JAMTEST ID ITEST B-1 S-2 5' Soil 23-A018155 CONV B-2 S-3 7.5' Soil 23-A018156 CONV B-4 S-4 10' Soil 23-A018157 CONV Your samples were received on Monday,October 16,2023.At the time of receipt,the samples were logged in and properly maintained prior to the subsequent analysis. The analytical procedures used at AmTest are well documented and are typically derived from the protocols of the EPA,USDA,FDA or the Army Corps of Engineers. Following the analytical data you will find the Quality Control(QC)results. Please note that the detection limits that are listed in the body of the report refer to the Practical Quantitation Limits(PQL's),as opposed to the Method Detection Limits(MDL's). If you should have any questions pertaining to the data package,please feel free to contact me. Sincerely, 410-vi W " Aaron Young Vice President Project#: 2760.01 BACT=Bacteriological MET=Metals NUT=Nutrients MIN=Minerals CONV=Conventionals ORG=Organics DEM=Demand P.1 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Am Test Inc. Professional 13600 NE 126TH PL Analytical Suite C Services Kirkland,WA 98034 AWFwW (425)885-1664 L A 8 O R A T O R 1 E 8 www.amtestlab.com ANALYSIS REPORT ZIPPER GEO ASSOCIATES, LLC Date Received: 10/16/23 19019 36TH AVENUE W Date Reported: 10/25/23 LYNNWOOD, WA 98036 Attention: JAMES GEORGIS Project Name:ARLINGTON COMMERCIAL DEVELOPMENT Project#:2760.01 All results reported on an as received basis. AMTEST Identification Number 23-AO18155 Client Identification B-1 S-2 5' Sampling Date 10/16/23 Conventionals PARAMETER RESULT UNITS Q D.L. METHOD JANALYST I DATE Cation Exchange Capacity 15.8 meq/100g 1 10.5 SW-846 9081 1CM 10/19/23 AMTEST Identification Number 23-AO18156 Client Identification B-2 S-3 7.5' Sampling Date 10/16/23 Conventionals PARAMETER RESULT UNITS IQ D.L. IMETHOD JANAILYST DATE Cation Exchange Capacity 6.3 meq/100g 1 10,5 ISW-846 9081 ,CM 10/19/23 P.2 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington ZIPPER GEO ASSOCIATES,LLC Project Name:ARLINGTON COMMERCIAL DEVELOPMENT AmTest I D:23-AO18157 AMTEST Identification Number 23-A018157 Client Identification B-4 S-4 10' Sampling Date 10/16/23 Conventionals PARAMETER RESULT UNITS 10 D.L METHOD JANALYST I DATE Cation Exchange Capacity 16.5 meq/100g 1 10.5 SW-846 9081 J CM 10/19/23 L". " --'-7 Aar n Young Vice President P.3 PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Am Test Inc. Professional 13600 NE 126th PL Analytical Suite C AWFST Services Kirkland,WA,98034 (425)885-1664 L A B O R A T O R 1 E S www.amtestlab.com OC Summary for sample numbers:23-AO18155 to 23-AO18157 DUPLICATES SAMPLE# JANALYTE UNITS ISAMPLEVALUE IDUPVALUE I RPD 23-AO17935 Cation Exchange Capacity meq/100g 2.7 2.9 7.1 23-AO18157 Cation Exchange Capacity meq/100g 6.5 5.1 24. STANDARD REFERENCE MATERIALS ANALYTE UNITS ITRUE VALUE MEASURED VALUE IRECOVERY Cation Exchange Capacity meq/100g 12.0 2.0 100.% Cation Exchange Capacity meq/100g 12.0 2.0 100.% BLANKS ANALYTE I UNITS IRESULT Cation Exchange Capacity meq/100g <0.1 Cation Exchange Capacity meq/100g <0.1 PA PACLAND Project#10980002 w@ Rabbi Express Car Wash k7mw»rslePlan Arlington,Washington / f R : § k ! f \ ƒ @ ! \ o ; \ co 0 / k / -J 0 \ § \ } ; > / § § 7 K \ W / 3 k k \ 0 t ■ - ) > a 6 ! ! ! ) Cr m�__n = , , ■ 110sw, , m m ! ! _e# $ \ / ®®% k { \ f k 0 E __e, = o } 2 �} ) Sj \ 0 0 .. - \SE / } g. kk N / \ ! © / E E COi / / (k - § ; § $ k( / ƒo 0 _ \ e_e01=1103d S t ( / &a_OO kj mnm ® ® ® £ » &__a „ f / g8n»m « < ; i ® § ��wLLOU E g k Oeej, , ,HId3O © \ / \ ) _IVN__ mIVM one ) \ PAEUND Project#mg802 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Appendix D — Stormwater Operations & Maintenance PACLAND Project#10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Maintain Stormwater Facilities The owner or operator of the project shall be responsible for maintaining the stormwater facilities in accordance with local requirements. Proper maintenance is important for adequate functioning of the stormwater facilities. The following maintenance program is recommended for this project: PACLAND Project# 10980002 Wet Rabbit bp@a Car Wash aemw Sr»@ man Arlington,Washington \ \ k | § 2 K e \ \ \ \ r \ \ $ \/ & @ } /.§ &§ \ » 2 7 } I § & 02 .§ 2 c ® � � � \ \ 2 2 ° = / CZ k e } 2 g be0 ; \ \ } § § � A2 : .� UC ° E k '20 k .E k 2 § § tom 0 u ° f § 92 ? § b ) col } ( e 2 $ \ 7 \ \ ) \ \ { Ek \ ? \ § k \ } 2 0 a � V -0 Z ; / § \ ( ) \ ] � 77 � o # # 7 ) [ 3 m ( \ /R § / kk 'u E 3 � s a § R33 § . . .( § . . c mN D Project# 10980002 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Appendix E — Construction SWPPP PACLAND Project#10980002 GEOTECHNICAL ENGINEERING REPORT ARLINGTON COMMERCIAL DEVELOPMENT 7530 204T" STREET NE ARLINGTON, WASHINGTON ZGA Project No. 2760.01 March 28, 2024 Prepared for: WET RABBIT, LLC vT I.L .�1 Prepared by: ZipperGeo Geoprofessional Consultants 19019 36th Avenue W., Suite E Lynnwood, WA 98036 Zipp Geo Geoprofessional Consultants ZGA Project No. 2760.01 March 28, 2024 Wet Rabbit, LLC 3213 West Wheeler Street, #750 Seattle, Washington 98199 Attention: Mr. Chris McClure Subject: Geotechnical Engineering Report Arlington Commercial Development 7530 204t"Street NE Arlington, Washington 98223 Parcel Numbers 310514-001-006-00 and 310514-001-010-00 Dear Mr. McClure, In accordance with your request and written authorization,Zipper Geo Associates, LLC(ZGA) has completed the subsurface evaluation and geotechnical engineering report for the above-referenced project. This report presents the findings of the subsurface evaluation and geotechnical recommendations for the project design and construction.Our services have been completed in general accordance with our Proposal for Geotechnical Services (Proposal No. P23120) dated September 22, 2023. Written authorization to proceed was provided by you on September 22, 2023. We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report,or if we may be of further service, please contact us. Sincerely, Zipper Geo Associates, LLC 0Cf W ashA. co O�oR wA ti G,P 4 atAm—A - c ,n s• x 2 � t��� 3128124 •off 38384 3128124 hied o�o RIN At, .LAMES P. (3EORllIS James P. Georgis, L.E.G. Robert A. Ross, P.E. Principal Principal 19019 36t"Avenue West, Suite E Lynnwood, WA 98036 (425) 582-9928 TABLE OF CONTENTS Page 1.0 INTRODUCTION .....................................................................................................................1 1.1 Site Description........................................................................................................................ 1 1.2 Project Understanding.............................................................................................................2 2.0 SUBSURFACE CONDITIONS.....................................................................................................2 2.1 Published Geologic Information..............................................................................................2 2.2 Soil Conditions.........................................................................................................................2 2.3 Groundwater Conditions.........................................................................................................3 3.0 CONCLUSIONS AND RECOMMENDATIONS..............................................................................4 3.1 General ....................................................................................................................................4 3.2 Seismic Design Considerations................................................................................................5 3.3 Site Preparation.......................................................................................................................7 3.4 Structural Fill............................................................................................................................9 3.5 Utility Trenching and Backfilling............................................................................................11 3.6 Temporary Shoring................................................................................................................12 3.7 Temporary and Permanent Slopes........................................................................................12 3.8 Corrosion Considerations ......................................................................................................13 3.9 Shallow Foundations..............................................................................................................13 3.10 On-Grade Concrete Floor Slabs.............................................................................................14 3.11 Mat Foundation Option.........................................................................................................15 3.12 Backfilled Walls......................................................................................................................17 3.13 Drainage Considerations........................................................................................................17 3.14 Infiltration Considerations.....................................................................................................18 3.15 Pavements.............................................................................................................................20 4.0 CLOSURE..............................................................................................................................21 FIGURES Figure 1—Site and Exploration Plan APPENDICES Appendix A—Subsurface Exploration Procedures and Logs Appendix B—Laboratory Testing Procedures and Results GEOTECHNICAL ENGINEERING REPORT ARLINGTON COMMERCIAL DEVELOPMENT 7530 204T" STREET NE ARLINGTON, WASHINGTON Project No. 2760.01 March 28, 2024 1.0 INTRODUCTION This report presents the surface and subsurface conditions encountered at the site and our geotechnical engineering recommendations for the proposed Arlington Commercial Development. Our scope of services included reviewing readily available geologic data, a site reconnaissance, subsurface evaluation, laboratory testing, geotechnical engineering analysis, and preparation of this report. The project description,site conditions, and our geotechnical conclusions and recommendations are presented in the text of this report. Supporting data including detailed exploration logs and field exploration procedures and the results of laboratory testing are presented as appendices. 1.1 Site Description The site is comprised of two adjoining Snohomish County tax parcels. Tax Parcel 310514-001-006-00 is a developed site with a property address of 7530 204th Street NE in Arlington, Washington. According to Snohomish County Assessor's records, the developed parcel encompasses 0.86 acres of relatively level land with an unoccupied commercial building formerly occupied by Arlington Family Medicine located in the southeastern portion of the parcel. The building is a 3,520 square foot, one-story, wood-framed structure reportedly build in 1984.Asphalt surfaced drive lanes and parking are found to the north,west, and south of the commercial building.The development is services by underground utilities and includes a stormwater system. Vegetation includes ornamental plantings in parking lot islands and around the building, a row of large trees along the west and south property lines which appear to serve as a wind block, and a lawn south of the building. Asphalt pavements near the west and south rows of trees exhibit moderate root damage. Tax Parcel 310514-001-010-00 is a relatively level, undeveloped site located east of and adjoining the southern portion of the above discussed developed parcel's east property line. The parcel is irregular in shape and according to Snohomish County Assessor's records encompasses 0.81 acres. It appears that some underground utilities may be located near the east property line. Vegetation within the undeveloped parcel primarily consists of well-developed tall grasses with dense blackberry brush along its west and north property lines. A roughly "L" shaped drainage ditch is located along the northern portion of the developed parcels east property line and along the entire north property line of the undeveloped parcel. Running water of about 3 to 4 inches deep was observed in the drainage ditch during our site reconnaissance. The enclosed Site and Exploration Plan, Figure 1, includes an aerial photograph of the subject parcels. Page 1 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants 1.2 Project Understanding We understand that Wet Rabbit, LLC intends to redevelop the currently vacant developed parcel (310514- 001-006-00) with a new Wet Rabbit-branded car wash facility. We understand that redevelopment will generally include demolition of the existing structure, minor regrading, construction of a new drive-thru car wash tunnel in the west-central west side of the site, and reconfiguration and repaving of the parking lot and drive lanes. We understand that development of the currently undeveloped parcel (310514-001- 010-00) may include a one-story Quick Service Restaurant (QSR) or similar commercial development. Lightly loaded shallow foundations with slab-on-grade floors are anticipated. We understand that stormwater management design will be completed in accordance with the 2014 Washington State Department of Ecology (Ecology) Stormwater Management Manual for Western Washington (Stormwater Manual).We understand that a below grade infiltration gallery is planned in the east-central portion of the western developed parcel with a bottom of facility elevation of about 122.5 feet. We understand that a stormwater infiltration pond is planned in the western portion of the eastern undeveloped parcel with a bottom of pond elevation of about 124 feet. 2.0 SUBSURFACE CONDITIONS 2.1 Published Geologic Information We assessed the geologic setting of site and the surrounding vicinity by reviewing the Geologic Map of the Arlington West Quadrangle, Snohomish County, Washington (US Geological Survey, Map MF-1740, 1985). The published geologic mapping shows the site is underlain by Vashon Recessional Outwash, Marysville Sand Member. The Marysville Sand Member is described as mostly well-drained, stratified to massive outwash sand, with some fine gravel, and some areas of silt and clay. The sediments were deposited by melt water flowing south from the stagnating and receding Vashon glacier. The outwash is reported to have a maximum thickness of about 140 feet. Subsurface conditions disclosed by the explorations advanced for this evaluation are consistent with the published mapping. 2.2 Soil Conditions The subsurface evaluation completed by ZGA for this project included four borings (13-1 through 13-4) and one cone penetrometer test (CPT-01). CPT-01 was completed near the center of the proposed car wash development(currently developed western parcel) and extended to a depth of about 60 feet below grade. The CPT exploration included seismic shear wave velocity measurements. Borings B-1 and B-2 were completed in the north and south portions of the western parcel's existing parking lot, respectively, and extended about 36% feet below grade. Borings B-3 and B-4 were completed in the undeveloped eastern parcel and extended about 31%to 36% feet below grade. Groundwater monitoring wells were installed in borings B-1 through B-3 to evaluate changes in groundwater levels through the wet season. The enclosed Site and Exploration Plan, Figure 1, presents the approximate locations of our subsurface explorations completed for this project. Soil samples recovered from the borings were visually classified in general accordance with the Explanation of Exploration Logs enclosed in Appendix A. Detailed, descriptive logs of the subsurface explorations and the procedures utilized in the subsurface exploration program are also presented in Page 2 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants Appendix A. In general, our explorations disclosed asphalt pavement and topsoil over recessional glacial outwash deposits interpreted as the Marysville Sand Member.Generalized descriptions of subsurface soil conditions observed at the exploration locations are presented below. 2.2.1 Pavement Section Borings B-1 and B-2 were completed in the parking lot of the western parcel and encountered about 2 inches of asphalt.The thickness of the pavement at the CPT location could not be accurately determined due to the small diameter of the conical probe used to complete the exploration. 2.2.2 Topsoil Borings B-3 and B-4 were completed in the undeveloped eastern parcel and encountered about 3 to 4 inches of topsoil. In general,the topsoil consisted of loose, brown sand with silt and abundant fine roots. 2.2.3 Glacial Recessional Outwash Soil interpreted as glacial recessional outwash deposits of the Marysville Sand Member were encountered below the pavement in the western parcel and below the topsoil in the eastern undeveloped parcel.The glacial outwash deposits extended to the maximum depth explored of 36%feet in the borings and 60 feet in the CPT. In general, the upper 5 to 7%2 feet of the outwash consists of loose to medium dense sand with variable silt and silt with variable sand content.Soil mottling was observed in some of the samples collected in this depth range. From about 5 to 7% feet down to about 15 to 17% feet, the outwash generally consists of medium dense to very dense gravelly sand to sandy gravel with trace to some silt. From about 15 to 17% feet to the maximum depth explored at 60 feet below grade, the outwash generally consists of loose to medium dense sand with trace to some silt. 2.3 Groundwater Conditions Groundwater was observed in borings B-1 through B-3 about 25 to 30 feet below grade at the time of drilling. Groundwater monitoring wells were installed in borings B-1 through B-3. Groundwater monitoring well readings are typically more accurate than groundwater depth estimates completed at the time of drilling and are presented in the table below. Groundwater Monitoring Well Data Boring Approx.Surface Date of Groundwater Approx.Depth to Approx.Groundwater Number Elevation (ft) Measurement Groundwater(ft) Elevation(ft) 10/17/23 25.41 102.21 10/19/23 25.81 101.81 11/13/23 25.23 102.39 B-1 127.62 12/19/23 24.73 102.89 01/24/24 12.98 114.64 02/16/24 11.91 115.71 03/26/24 10.64 116.98 Page 3 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants Groundwater Monitoring Well Data Boring Approx.Surface Date of Groundwater Approx.Depth to Approx.Groundwater Number Elevation (ft) Measurement Groundwater(ft) Elevation(ft) 10/17/23 27.37 102.42 10/19/23 27.18 102.61 11/13/23 27.41 102.38 B-2 129.79 12/19/23 23.91 105.88 01/24/24 16.50 113.29 02/16/24 14.41 115.38 03/26/24 13.37 116.42 10/17/23 28.62 103.38 10/19/23 28.83 103.17 11/13/23 28.65 103.35 B-3 132.00 12/19/23 24.70 107.30 01/24/24 17.05 114.95 02/16/24 15.61 116.39 03/26/24 14.75 117.25 Ground surface elevations at the exploration locations are based on survey data provided by PacLand. Groundwater levels, flow rates and soil moisture conditions should be expected to vary throughout the year. Fluctuations of the groundwater levels will likely occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the explorations were performed. Therefore, groundwater levels during construction or at other times in the life of the development should be expected to vary. 3.0 CONCLUSIONS AND RECOMMENDATIONS 3.1 General Based on the results of our subsurface explorations, laboratory testing, and geotechnical engineering analyses, we conclude that the proposed development is feasible from a geotechnical standpoint, contingent on proper design and construction practices. The explorations completed for our evaluation encountered soils susceptible to seismic induced liquefaction settlements.This condition requires special design considerations, as discussed below. The liquefaction potential of the development was evaluated in accordance with the 2018 International Building Code (IBC). Based on our analysis, we estimate total seismic settlements of approximately 3 to 3% inches could occur during the design earthquake. We estimate differential seismic settlements of approximately 1% to 1% inches over a horizontal distance of 40 feet. In our experience, these levels of total and differential seismic settlement are typically considered expectable for most structures from a collapse prevention perspective, but should be evaluated by the owner relative to risk management and the project structural engineer relative to 2018 IBC design requirements and the specific building design being considered. If these levels of potential seismic settlement are not considered acceptable for conventional spread footings, we recommend that a mat foundation be considered. Due to the presence Page 4 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants of about 10 to 15 feet of dense to very dense gravelly soils above the potential zone of liquefaction,ground improvement methods, such as stone columns, are not recommended for liquefaction mitigation at this site. This report includes geotechnical design recommendations for both conventional spread and mat foundation options. Geotechnical engineering recommendations for foundation systems and other earthwork related phases of the project are outlined below. The recommendations contained in this report are based upon the results of field and laboratory testing(which are presented in Appendices A and B), engineering analyses, and our current understanding of the proposed project. ASTM and Washington State Department of Transportation (WSDOT) specification codes cited herein respectively refer to the current manual published by the American Society for Testing & Materials and the current edition of the Standard Specifications for Road, Bridge, and Municipal Construction, (M41-10). 3.2 Seismic Design Considerations The seismic performance of the proposed development was evaluated relative to seismic hazards resulting from ground shaking associated with a design seismic event with a 2,475-year return period determined in accordance with the 2018 International Building Code (IBC). Conformance to the above criteria for seismic excitation does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur if a maximum level earthquake occurs.The primary goal of the IBC seismic design procedure is to protect life and not to avoid all damage, since such design may be economically prohibitive. Following a major earthquake, a building may be damaged beyond repair, yet not collapse. 3.2.1 Ground Fault Rupture Based on review of the United States Geological Survey Quaternary Fault and Fold Database of the United States there are no mapped Quaternary faults within 10 miles of the site. It is our opinion that the risk of ground surface rupture at the site is low. 3.2.2 Landsliding Based on the relatively level topography of the site and surrounding vicinity, it is our opinion that the risk of earthquake-induced landsliding is low. 3.2.3 Liquefaction Liquefaction is a phenomenon wherein saturated cohesionless soils build up excess pore water pressures during earthquake loading. Liquefaction typically occurs in loose soils, but may occur in denser soils if the ground shaking is sufficiently strong. ZGA completed a liquefaction analysis in general accordance with the 2018 IBC and ASCE 7-16. Specifically, our analysis used the following primary seismic ground motion parameters. • A Maximum Considered Earthquake Geometric Mean (MCEG) Peak Ground Acceleration of 0.441g, based on Figure 22-9 of ASCE 7-16. Page 5 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants • A Modified Peak Ground Acceleration (PGQ of 0.511g based on Site Class D, per Section 11.8.3 of ASCE 7-16 (Site Class modification to MCEG without regard to liquefaction in accordance with Sections 11.4.8 and 20.3.1 of ASCE 7-16). • A Geometric Mean Magnitude of 6.8 based on 2014 USGS National Seismic Hazard Mapping Project deaggregation data for a seismic event with a 2% probability of exceedance in 50 years (2,475 year return period). Our liquefaction analysis was completed using the computer program CLiq (Version 3.5.2.10) developed by GeoLogismiki. Our analysis was based on CPT-1 completed to a depth of about 60 feet below existing grade. The approximate exploration location is shown on the enclosed Site and Exploration Plans, Figure 1. Our analysis indicates the potential for liquefaction below the groundwater table,which was modeled at a median depth of 20 feet below grade in our analysis. 3.2.3.1 Liquefaction Settlement Based on our analyses, we estimate a total seismic settlement of approximately 3 to 3% inches. We estimate a differential seismic settlement of approximately 1%to 1% inches over a horizontal distance of 40 feet. If these levels of seismic induced liquefaction settlement are not acceptable for conventional spread footings,we recommend that a mat foundation be considered as discussed in subsequent sections of this report. 3.2.3.2 Lateral Spread Lateral spreading is a phenomenon in which soil deposits which underlie a site can experience significant lateral displacements associated with the reduction in soil strength caused by soil liquefaction. This phenomenon tends to occur most commonly at sites where the soil deposits can flow toward a "free- face", such as a water body. Given the relatively level nature of the site and lack of a free-face condition, it is our opinion that the potential for distress at the site from lateral spreading is low. 3.2.4 IBC Seismic Design Parameters Per the 2018 IBC seismic design procedures and ASCE 7-16,the presence of liquefiable soils requires a Site Class definition of F. However, through reference to Sections 11.4.8 and 20.3.1 of ASCE 7-16, the 2018 IBC allows site coefficients Fa and F" to be determined assuming that liquefaction does not occur for structures with fundamental periods of vibration less than 0.5 seconds. Based on the results of the field evaluation, Site Class D may be used to determine the values of Fa and F" in accordance with Sections 11.4.8 and 20.3.1 of ASCE 7-16. If exceptions for Site Class D presented in Section 11.4.8 of ASCE 7-16 do not apply, a ground motion hazard analysis may be required. IBC Seismic Design Criteria Parameter Value 2018 International Building Code Site Classification(I13C)1 Site Class F 2,3 Site Latitude/Longitude 48.1803/-122.1283 Spectral Short-Period Acceleration,Ss 1.038g Page 6 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants IBC Seismic Design Criteria Parameter Value Spectral 1-Second Acceleration,Si 0.371g Site Coefficient for a Short Period,FA 1.085 Site Coefficient for a 1-Second Period, Fv See ASCE Section 11.4.8 Spectral Acceleration for a 0.2-Second Period,SMs 1.126g Spectral Acceleration for a 1-Second Period,SMi See ASCE Section 11.4.8 Design Short-Period Spectral Acceleration,Sos 0.751g Design 1-Second Spectral Acceleration,Soi See ASCE Section 11.4.8 1. IBC Site Class is based on the average characteristics of the upper 100 feet of the subsurface profile. 2. The explorations completed for this study extended to a maximum depth of about 60 feet below grade. ZGA therefore determined the Site Class assuming that medium dense to dense glacial outwash soils with an average n value greater than 15 extend to 100 feet as suggested by published geologic maps for the project area. 3. Per the 2018 International Building Code and ASCE 7-16, Chapter 20, any profile containing soils vulnerable to potential failure or collapse under seismic loading such as liquefiable soils. 3.3 Site Preparation 3.3.1 Existing Structure Removal The western parcel is currently developed with an unoccupied commercial building with associated asphalt pavement and concrete flatwork. After the building is removed, we recommend that any remaining foundation elements or other below grade structures, if encountered, be demolished and removed from the proposed development areas. We recommend that the resulting excavation be backfilled with compacted structural fill. 3.3.2 Existing Utility Removal We recommend that all underground utilities within the prosed building pad be completely removed. Utility pipes outside the building envelope could be abandoned in place, provided they are fully grouted with controlled density fill (CDF) and the trench backfill is density tested to verify that it meets the compaction levels presented in the project specifications. Localized excavations made for removal of utilities or existing unsuitable trench backfill should be backfilled with structural fill as outlined in the following section of this report. 3.3.3 Erosion Control Measures Stripped surfaces and soil stockpiles are typically a source of runoff sediments. We recommend that silt fences, berms, and/or swales be installed around the downslope side of stripped areas and stockpiles in order to capture runoff water and sediment. If earthwork occurs during wet weather, we recommend that all stripped surfaces be covered with straw to reduce runoff erosion, whereas soil stockpiles should be protected with anchored plastic sheeting. Page 7 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants 3.3.4 Temporary Drainage Stripping, excavation,grading,and subgrade preparation should be performed in a manner and sequence that will provide drainage at all times and provide proper control of erosion. The upper 5 to 7% feet of the site soils have a moderate fines (silt and clay) content and are therefore susceptible to disturbance and erosion when wet. The site should be graded to prevent water from ponding in construction areas and/or flowing into and/or over excavations. Exposed grades should be crowned, sloped, and smooth- drum rolled at the end of each day to facilitate drainage if inclement weather is forecasted. Accumulated water must be removed from subgrades and work areas immediately and prior to performing further work in the area. Equipment access may be limited, and the amount of soil rendered unfit for use as structural fill may be greatly increased if drainage efforts are not accomplished in a timely manner. 3.3.5 Clearing and Stripping Vegetation in the western developed parcel includes ornamental plantings in parking lot islands and around the building, a row of large trees along the west and south property lines which appear to serve as a wind block, and a lawn south of the building. Asphalt pavements near the west and south rows of trees exhibit moderate root damage. We anticipate that clearing and stripping depths on the order of 6 to 12 inches may be required in landscaped areas. Deeper excavations may be needed to remove tree roots along the south and west sides of the site. Vegetation within the undeveloped eastern parcel primarily consists of well-developed tall grasses with dense blackberry brush along its west and north property lines. Based on borings B-3 and B-4,we anticipate topsoil stripping depths on the order of 4 to 6 inches in the eastern parcel. Any excavations that extend below finish grades should be backfilled with structural fill as outlined subsequently in this report. 3.3.6 Subgrade Preparation and Protection Once site preparation is complete, all areas that do not require over-excavation and are at design subgrade elevation or areas that will receive new structural fill should be compacted to a firm and unyielding condition, and to achieve the recommended compaction level within the upper 12 inches of exposed subgrade soil presented in Section 3.5.6 of this report. Some moisture conditioning of site soils may be required to achieve a moisture content appropriate for compaction. This is generally within ±2 percent of the soil's optimum moisture content determined in accordance with ASTM D 1557 test procedure. Our laboratory testing indicates that, at the time our explorations were completed, in-situ moisture contents collected from the upper 5 feet of the site range from about 5 to 29 percent. As a result, we expect that moisture conditioning of site soils during construction will be required to achieve suitable moisture contents(plus or minus two percent of optimum)for compaction. Earthwork should be completed during drier periods of the year when soil moisture content can be controlled by aeration and drying if possible. If earthwork or construction activities take place during extended periods of wet weather, it will be difficult to achieve a firm, non-yielding surface and recommended compaction levels. In the event the exposed subgrade becomes unstable, yielding, or unable to be compacted due to high moisture conditions, we recommend that the materials be removed to a sufficient depth in order to develop stable subgrade soils that can be compacted to the minimum Page 8 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants recommended levels.The severity of construction problems will be dependent,in part,on the precautions that are taken by the contractor to protect the subgrade soils. Once compacted, subgrades should be evaluated through density testing and proof rolling with a loaded dump truck or heavy rubber-tired construction equipment weighing at least 20 tons to assess the subgrade adequacy and to detect soft and/or yielding soils. In the event that compaction fails to meet the specified criteria, the upper 12 inches of subgrade should be scarified, and moisture conditioned as necessary to obtain the specified compaction level. Those soils which are soft, yielding, or unable to be compacted to the specified criteria should be over-excavated and replaced with suitable material as recommended in the Structural Fill section of this report. To protect stable subgrades in the wet season, we recommend using crushed rock. The thickness of the protective layer should be determined at the time of construction and be based on the moisture condition of the soil and the amount of anticipated traffic. 3.3.7 Freezing Conditions If earthwork takes place during freezing conditions, all exposed subgrades should be allowed to thaw and then be compacted prior to placing subsequent lifts of structural fill or pouring foundations. Alternatively, the frozen material could be stripped from the subgrade to expose unfrozen soil prior to placing subsequent lifts of fill or foundation components. The frozen soil should not be reused as structural fill until allowed to thaw and adjusted to the proper moisture content, which may not be possible during winter months. 3.4 Structural Fill Structural fill includes any material placed below foundations, floor slabs, and pavement sections, within utility trenches, and behind retaining walls. Prior to the placement of structural fill,all surfaces to receive fill should be prepared as previously recommended in the Site Preparation section of this report. 3.4.1 Laboratory Testing Representative samples of on-site and imported soils to be used as structural fill should be submitted for laboratory testing at least four days in advance of its intended use and required density testing in order to complete the necessary Proctor tests. 3.4.2 Re-Use of Site Soils as Structural Fill It is our opinion that the soils encountered on the site are adequate for reuse as structural fill from a compositional standpoint provided it is placed and compacted in accordance with the recommendations presented in this report. Our laboratory testing indicates that, at the time our explorations were completed, in-situ moisture contents collected from the upper 5 feet of the site range from about 5 to 29 percent. As a result, we expect that some moisture conditioning during construction of site soils will be required to achieve suitable moisture contents (plus or minus two percent of optimum) for compaction. Drying of over-optimum moisture soils may be achieved by scarifying or windrowing surficial materials during extended periods of dry weather. If encountered, soils which are dry of optimum may be Page 9 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants moistened through the application of water and thorough blending to facilitate a uniform moisture distribution in the soil prior to compaction. We recommend that site soils used as structural fill have less than 4 percent organics by weight, have no woody debris greater than %-inch in diameter, and contain no other deleterious materials. We recommend that all pieces of organic material greater than %-inch in diameter be picked out of the fill before it is placed and compacted. Deleterious debris includes waste building materials, organics, trash, and asphalt and, if encountered, it should be removed from the soil prior to its reuse as structural fill. 3.4.3 Imported Structural Fill If additional material is required for grading and fills, the appropriate type of imported structural fill will depend on the weather conditions. During extended periods of dry weather, we recommend imported fill meet the requirements of Common Borrow, Options 1 or 2 as specified in Section 9-03.14(3) of the 2023 Washington State Department of Transportation, Standard Specifications for Road, Bridge, and Municipal Construction (WSDOT Standard Specifications). The on-site soils would generally be classified as Common Borrow. During wet weather, higher-quality (lower fines content) structural fill might be required, as Common Borrow may contain sufficient fines to be moisture sensitive. During wet weather we recommend that imported structural fill meet the requirements of Gravel Borrow as specified in Section 9-03.14(1) of the 2023 WSDOT Standard Specifications. 3.4.4 Moisture Content The suitability of soil for use as structural fill will depend on the prevailing weather at the time of construction,the moisture content of the soil, and the fines content(that portion passing the U.S. No. 200 sieve) of the soil. As the amount of fines increases, the soil becomes increasingly sensitive to small changes in moisture content. Soils containing more than about 5 percent fines (such as most of the on- site soils encountered in the upper 2 feet of the site)cannot be consistently compacted to the appropriate levels when the moisture content is more than approximately 2 percent above or below the optimum moisture content (per ASTM D1557). Optimum moisture content is that moisture content which results in the greatest compacted dry density with a specified compactive effort. The moisture content of fill at the time of placement should be within plus or minus 2 percent of optimum moisture content for compaction as determined by the ASTM D1557 test method. 3.4.5 Fill Placement We recommend that structural fill be placed in horizontal lifts not exceeding 8 inches in loose thickness and each lift of fill be compacted using compaction equipment suitable for the soil type and lift thickness to the minimum levels recommended below based on the maximum laboratory dry density as determined by the ASTM D1557 Modified Proctor Compaction Test. 3.4.6 Compaction Criteria Our recommendations for soil compaction are summarized in the following table. We recommend that a geotechnical engineer be present during grading so that an adequate number of density tests may be conducted as structural fill placement occurs. Page 10 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants RECOMMENDED SOIL COMPACTION LEVELS Location Minimum Percent Compaction* All fill below building floor slabs and foundations 95 Upper 2 feet of fill below exterior slabs and pavements 95 Pavement and exterior slab fill below two feet 92 Upper two feet of utility trench backfill 95 Utility trenches below two feet 92 Landscape areas 90 * ASTM D1557 Modified Proctor Maximum Dry Density 3.5 Utility Trenching and Backfilling We recommend that utility trenching conforms to all applicable federal, state, and local regulations, such as OSHA and WISHA, for open excavations. Trench excavation safety guidelines are presented in WAC Chapter 296-155 and WISHA RCW Chapter 49.17. 3.5.1 Trench Dewatering Groundwater was encountered in borings B-1 through B-3 at depths of about 25 to 30 feet below existing grade at the time of our evaluation. As such, significant construction dewatering associated with utility installations is not anticipated. However, some excavations for utilities and underground structures may encounter zones of perched groundwater that may develop above lower permeability layers in the site outwash soils.The amount of perched groundwater seepage that may be encountered in site excavations will likely be a function of the time of year,the size of the excavation,the excavation depth,and how long the excavation remains open. The type and extent of dewatering measures needed, if any, will be a function of the groundwater conditions at the time of construction. Temporary systems could include pumped sumps, wellpoints, or pumped wells. If dewatering becomes necessary,the appropriate type of dewatering system and means of water disposal should be determined by the contractor based on the conditions encountered. 3.5.2 Utility Subgrade Preparation We recommend that all utility subgrades be firm and unyielding and free of soils that are loose,disturbed, or pumping. Soils that pump or yield should be removed and replaced. All structural fill used to replace over-excavated soils should be compacted as recommended in the Structural Fill section of this report. 3.5.3 Bedding and Initial Backfill We recommend that a minimum of 4 inches of bedding material be placed above and below all utilities or in general accordance with the utility manufacturer's recommendations and local ordinances. We recommend that pipe bedding consist of Gravel Backfill for Pipe Zone Bedding as specified in Section 9- 03.12(3) of the 2023 WSDOT Standard Specifications. All trenches should be wide enough to allow for compaction around the haunches of the pipe, or material such as pea gravel should be used below the Page 11 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants spring line of the pipes to eliminate the need for mechanical compaction in this portion of the trenches. If water is encountered in the excavations, it should be removed prior to fill placement. 3.5.4 Trench Backfill Materials, placement and compaction of utility trench backfill should be in accordance with the recommendations presented in the Structural Fill section of this report. In our opinion, the initial lift thickness should not exceed 1 foot unless recommended by the manufacturer to protect utilities from damage by compacting equipment. Light, hand operated compaction equipment may be utilized directly above utilities if damage resulting from heavier compaction equipment is of concern. 3.6 Temporary Shoring We recommend that temporary shoring systems be used where excavations will be located adjacent to existing foundations, property lines, roadways or utilities, or where ground loss could damage existing facilities. A trench box is one type of support system which might be used. The zone between the trench box and the excavation face should be backfilled as necessary to limit ground movements. As an alternative, braced or unbraced shoring of various types could be considered. 3.7 Temporary and Permanent Slopes Temporary excavation slope stability is a function of many factors, including: • The presence and abundance of groundwater; • The type and density of the various soil strata; • The depth of cut; • Surcharge loadings adjacent to the excavation; and • The length of time the excavation remains open. It is exceedingly difficult under the variable circumstances to pre-establish a safe and "maintenance-free" temporary cut slope angle. For planning purposes, temporary cuts in loose soils on the order of 1.5H:1V and temporary cuts in medium dense to very dense soils on the order of 1H:1V could be considered. These planning level temporary cut slope inclinations assume a drained condition. Flatter slopes may be needed if groundwater seepage is present. However, it should be the responsibility of the contractor to maintain safe temporary slope configurations since the contractor is continuously at the job site, able to observe the nature and condition of the cut slopes,and able to monitor the subsurface materials and groundwater conditions encountered. Unsupported vertical slopes or cuts deeper than 4 feet are not recommended. The cuts should be adequately sloped, shored, or supported to prevent injury to personnel from local sloughing and spalling.The excavation should conform to applicable Federal,State, and Local regulations. According to Chapter 296-155 of the Washington Administrative Code(WAC),the contractor should make a determination of excavation side slopes based on classification of soils encountered at the time of excavation. Temporary cuts may need to be constructed at flatter angles based upon the soil moisture, soil density, and groundwater conditions at the time of construction. Adjustments to the slope angles should be determined by the contractor at that time. Page 12 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants We recommend that all permanent cut or fill slopes constructed in native or properly compacted fill soils be designed at a 2H:1V(Horizontal:Vertical) inclination or flatter. All permanent cut and fill slopes should be adequately protected from erosion both temporarily and permanently. 3.8 Corrosion Considerations Soils in the vicinity of the project site are considered to be very slightly corrosive to concrete and are not typically associated with high sulfate contents. As such, the relative degree of sulfate attack would be considered negligible and ASTM Type 1/11 Portland cement is suitable for all concrete below and at grade. 3.9 Shallow Foundations Based on our analyses, it is geotechnically feasible to support the proposed buildings on conventional shallow footings provided that foundation subgrades are properly prepared. We anticipate that foundation subgrade soils will generally consist of loose to medium dense sand with variable silt content. Our analyses indicate the potential for liquefaction induced settlement due to ground vibrations associated with the 2018 IBC design seismic event with a return period of 2,475 years. The foundation recommendations presented below assume that the levels of potential seismic settlement presented in Seismic Design Considerations section of this report (total seismic settlement of approximately 3 to 3% inches and differential seismic settlement of approximately 1%to 1% inches over a horizontal distance of 40 feet) are considered acceptable and meet the Life Safety and Collapse Performance objectives of the 2018 1 BC. If these conditions and levels of seismic settlement are not acceptable for the planned building, we recommend that the mat foundation option presented in this report be utilized to mitigate potential seismic settlements. However, if a mat foundation is utilized for the building, the spread foundation recommendations presented below may be used for ancillary structures determined by the structural engineer and owner to be less sensitive to potential seismic settlements. 3.9.1 Foundation Subgrade Preparation We recommend that the subgrade exposed at the bottom of foundation excavations be compacted to a firm and non-yielding condition and to at least 95 percent of the modified Proctor maximum dry density determined in accordance with ASTM D 1557. If the exposed subgrade cannot be compacted to the required density,we recommend that it be removed to a depth of 12 inches and be replaced with WSDOT Standard Specification Section 9-03.9(3),Crushed Surfacing Base Course compacted to at least 95 percent of the modified Proctor maximum dry density. We recommend that the over-excavation extend outside the limits of the footings a distance equal to the depth of over-excavation. 3.9.2 Allowable Bearing Pressure Continuous and isolated column footings bearing on compacted glacial outwash or structural fill placed and compacted in accordance with this report may be designed for a maximum allowable, net, bearing capacity of 2,000 psf. A one-third increase of the bearing pressure may be used for short-term transient Page 13 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants loads such as wind and seismic forces. The above-recommended allowable bearing pressure includes a 3.0 factor of safety. 3.9.3 Shallow Foundation Depth and Width For frost protection, the bottom of all exterior footings should bear at least 18 inches below the lowest adjacent outside grade,whereas the bottoms of interior footings should bear at least 12 inches below the surrounding slab surface level. We recommend that all continuous wall and isolated column footings be at least 12 and 24 inches wide, respectively. 3.9.4 Lateral Resistance Resistance to lateral loads can be calculated assuming an allowable passive resistance of 300 pcf equivalent fluid pressure (triangular distribution) and an allowable base friction coefficient of 0.35. The allowable passive resistance and friction coefficient include a 1.5 factor of safety. We recommend that passive resistance be neglected in the upper 18 inches of embedment. 3.9.5 Estimated Settlement Assuming the foundation subgrade soils, and structural fill compaction are completed in accordance with recommendations presented herein,we estimate that total and differential static settlements will be less than 1 inch and % inch over 40 feet, respectively. 3.10 On-Grade Concrete Floor Slabs Our analyses indicate the potential for liquefaction induced settlement due to ground vibrations associated with the 2018 IBC design seismic event with a return period of 2,475 years. The on-grade concrete floor slab recommendations presented below assume that the levels of potential seismic settlement presented in Seismic Design Considerations section of this report (total seismic settlement of approximately 3 to 3% inches and differential seismic settlement of approximately 1%to 1% inches over a horizontal distance of 40 feet) are considered acceptable. If these levels of seismic settlement are not acceptable,we recommend that the mat foundation option presented in this report be utilized to mitigate potential seismic settlements. 3.10.1 Subgrade Preparation After excavation to subgrade elevation,the base of the excavation is frequently disturbed or altered due to utility excavations, construction traffic, desiccation, or rainfall. As a result,the slab-on-grade subgrade may become unsuitable for floor slab support. We recommend that the slab subgrade be compacted to a firm and non-yielding condition and to at least 95 percent of the modified Proctor maximum dry density determined in accordance with ASTM D 1557. At the time of slab base placement, the subgrade should be evaluated by ZGA to verify a firm and non-yielding condition and adequate compaction. 3.10.2 Slab Base To provide a capillary break and uniform slab bearing surface, we recommend the on-grade slabs be underlain by a 4-inch thick layer of compacted clean crushed rock. In our opinion, the WSDOT Standard Specifications for Road, Bridge,and Municipal Construction does not include a material well suited for this Page 14 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants application below slabs. As such, we recommend that the capillary break conform to the graduation requirements for Type 21 or 22 Crushed Gravel as presented in the 2023 City of Seattle Standard Specifications for Road, Bridge, and Municipal Construction, Section 9-03.14, Mineral Aggregate Chart. Alternative capillary break materials should be submitted to the geotechnical engineer for review and approval before use. 3.10.3 Vapor Barrier Where potential slab moisture is a concern or where moisture sensitive floor coverings are planned, we recommend using a 15-mil, puncture-resistant proprietary product such as Stego Wrap, or an approved equivalent that is classified as a Class A vapor retarder in accordance with ASTM E 1745. Overlap lengths and the appropriate tape used to seal the laps should be in accordance with the vapor retarder manufacturer's recommendations. When conditions warrant the use of a vapor retarder, the slab designer and slab contractor should refer to ACI 302 and ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder/barrier. 3.11 Mat Foundation Option Our analyses indicate the potential for liquefaction induced settlement due to ground vibrations associated with the IBC design seismic event with a return period of 2,475 years. As discussed in the Seismic Design Considerations section of this report, we estimate a total seismic settlement of approximately 3 to 3% inches and a differential seismic settlement of approximately 1%to 1% inches over a horizontal distance of 40 feet for the 2018 IBC design earthquake.A mat foundation could be considered to mitigate this seismic settlement risk. Geotechnical recommendations for a mat foundation are presented below. 3.11.1 Subgrade Preparation After excavation to subgrade elevation,the base of the excavation is frequently disturbed or altered due to utility excavations, construction traffic, desiccation, or rainfall. As a result, the foundation subgrade may become unsuitable. We recommend that the upper foot of mat foundation subgrade be compacted to a firm and non-yielding condition and to at least 95 percent of the modified Proctor maximum dry density determined in accordance with ASTM D 1557. At the time of slab base placement, the subgrade should be evaluated by ZGA to verify a firm and non-yielding condition and adequate compaction. 3.11.2 Mat Foundation Base To provide a capillary break and uniform slab bearing surface, we recommend the on-grade slabs be underlain by a 6-inch thick layer of compacted clean crushed rock. In our opinion, the WSDOT Standard Specifications for Road, Bridge,and Municipal Construction does not include a material well suited for this application below slabs. As such, we recommend that the capillary break conform to the graduation requirements for Type 21 or 22 Crushed Gravel as presented in the 2023 City of Seattle Standard Specifications for Road, Bridge, and Municipal Construction, Section 9-03.14, Mineral Aggregate Chart. Alternative capillary break materials should be submitted to the geotechnical engineer for review and approval before use. Page 15 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants 3.11.3 Modulus of Subgrade Reaction For mat foundation design supported on 6 inches of compacted structural fill as described above, we recommend a vertical modulus of subgrade reaction of 200 pounds per cubic inch (pci) be used. This vertical modulus is for a 1-foot by 1-foot loaded area. 3.11.4 Allowable Bearing Pressure and Static Settlement The soil bearing capacities for mat foundations supported on granular soils are typically very large due to large foundation widths and are therefore typically controlled by allowable settlement. Based on a mat foundation width of about 40 feet, length of about 50 to 70 feet,and embedment depth of about 1.5 feet, we recommend an allowable, net soil bearing capacity of 3,000 psf to limit total static settlement to less than 1 inch and differential static settlement to less than % inch. A one-third increase of the bearing pressure may be used for short-term transient loads such as wind and seismic forces. Based on previous projects utilizing a mat foundation to support a structure of this size,we anticipate that actual loads would be substantially less than the allowable load of 3,000 psf.As such,total and differential static settlements are anticipated to be small. Settlements would occur elastically as loads are applied. 3.11.5 Mat Foundation Depth For frost protection, we recommend that the bottom of the mat foundation around the perimeter of the building bear at least 18 inches below the adjacent outside grade. 3.11.6 Lateral Resistance Resistance to lateral loads can be calculated assuming an allowable passive resistance of 300 pcf equivalent fluid pressure (triangular distribution) and an allowable base friction coefficient of 0.35. The allowable passive resistance and friction coefficient include a 1.5 factor of safety. We recommend that passive resistance be neglected in the upper 18 inches of embedment. 3.11.7 Vapor Barrier Where potential slab moisture is a concern or where moisture sensitive floor coverings are planned, we recommend using a 15-mil, puncture-resistant proprietary product such as Stego Wrap, or an approved equivalent that is classified as a Class A vapor retarder in accordance with ASTM E 1745. Overlap lengths and the appropriate tape used to seal the laps should be in accordance with the vapor retarder manufacturer's recommendations. When conditions warrant the use of a vapor retarder, the slab designer and slab contractor should refer to ACI 302 and ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder/barrier. 3.11.8 Estimated Seismic Settlements As discussed in the Seismic Considerations section of this report, our analyses indicate the potential for liquefaction induced settlement during the 2018 IBC design earthquake. Based on our analyses, we estimate a total seismic settlement of the soils beneath the slab of approximately 2% to 3 inches and a differential seismic settlement of approximately 1%to 1% inches over a horizontal distance of 40 feet. Page 16 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants 3.12 Backfilled Walls We anticipate that the development may include some backfilled, cast-in-place (CIP), concrete, building foundation and/or landscape retaining walls. For recommended bearing capacities and lateral resistance parameters, refer to Shallow Foundations(Section 3.9) of this report. Please refer to Section 3.13.3 of this report for wall drainage recommendations. Additional recommendations for CIP retaining walls are provided below. 3.12.1 Lateral Earth Pressures The lateral soil pressures acting on backfilled retaining walls will depend on the nature and density of the soil behind the wall, and the ability of the wall to yield in response to the earth loads. Yielding walls (i.e., walls that are free to translate or rotate)that are able to displace laterally at least 0.001H,where H is the height of the wall, may be designed for active earth pressures. Non-yielding walls (i.e.,walls that are not free to translate or rotate)should be designed for at-rest earth pressures. Non-yielding walls include walls that are braced to another wall or structure, and wall corners. For backfilled walls, assuming they are backfilled and drained in accordance with Section 3.12.3 of this report, we recommend that yielding walls supporting horizontal backfill be designed using an equivalent fluid density of 35 pcf(active earth pressure). Non-yielding walls should be designed using an equivalent fluid density of 55 pcf (at-rest earth pressure). Surcharge pressures due to sloping backfill, adjacent footings,vehicles, construction equipment,etc. must be added to these lateral earth pressure values. For traffic loads, we recommend using an equivalent two-foot soil surcharge of 250 psf. For retaining walls over 6 feet tall with level backfill conditions,we recommend that a uniformly distributed seismic pressure of 12H psf, where H is the height of the wall, be applied to the walls if required by code. The above equivalent fluid pressures are based on the assumption of no buildup of hydrostatic pressure behind the wall. If groundwater is allowed to saturate the backfill soils, hydrostatic pressures will act against a retaining wall. 3.13 Drainage Considerations 3.13.1 Surface Drainage Final site grades should be sloped to carry surface water away from buildings and other drainage-sensitive areas. Additionally, site grades should be designed such that concentrated runoff on softscape surfaces is avoided. Any surface runoff directed towards softscaped slopes should be collected at the top of the slope and routed to the bottom of the slope and discharged in a manner that prevents erosion. 3.13.2 Building Perimeter Foundation Drains and Wall Drains We recommend that the building be provided with a footing drain system to reduce the risk of future moisture problems. The footing drains should consist of a minimum 4-inch diameter, Schedule 40, rigid, perforated PVC pipe placed at the base of the heel of the footing with the perforations facing down. The pipe should be surrounded by a minimum of 6 inches of clean free-draining granular material conforming to 2023 WSDOT Standard Specification 9-03.12(4), Gravel Backfill for Drains. A non-woven filter fabric such as Mirafi 140N, or equivalent, should envelope the free-draining granular material. At appropriate Page 17 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants intervals such that water backup does not occur,the drainpipe should be connected to a tightline system leading to a suitable discharge.Cleanouts should be provided forfuture maintenance.The tightline system must be separate from the roof drain system. Roof drains should be connected to a separate solid wall PVC tightline system and routed to a suitable discharge location. 3.13.2 Backfilled Retaining Wall Drains Adequate drainage measures must be installed to collect and direct subsurface water away from subgrade walls. All backfilled walls should include a drainage aggregate zone extending 1% feet from the back of wall for the full height of the wall. The drainage aggregate should consist of material meeting the requirements of 2023 WSDOT 9-03.12(2) Gravel Backfill for Walls. A minimum 4-inch diameter, Schedule 40, rigid, perforated PVC pipe should be provided at the base of backfilled walls with the perforations facing down to collect and direct subsurface water to an appropriate discharge point. The pipe should be surrounded by a minimum of 6 inches of clean free-draining granular material conforming to 2023 WSDOT Standard Specification 9-03.12(4),Gravel Backfill for Drains. A non-woven filter fabric such as Mirafi 140N, or equivalent, should envelope the free-draining granular material. At appropriate intervals such that water backup does not occur,the drainpipe should be connected to a tightline system leading to a suitable discharge. Cleanouts should be provided for future maintenance. The tightline system must be separate from the roof drain system. 3.14 Infiltration Considerations We understand that stormwater management design will be completed in accordance with the 2014 Washington State Department of Ecology Stormwater Management Manual for Western Washington (2014 DOE Manual). We understand that a below grade infiltration gallery is planned in the east-central portion of the western developed parcel with a bottom of facility elevation of about 122.5 feet. We understand that a stormwater infiltration pond is planned in the western portion of the eastern undeveloped parcel with a bottom of pond elevation of about 124 feet. Based on the results of our subsurface exploration and analysis, shallow stormwater infiltration systems appear geotechnically feasible. The following sections provide geotechnical design recommendations regarding stormwater infiltration into the recessional glacial recessional outwash deposits encountered on site. 3.14.1 Design Infiltration Rates Soil conditions observed in the site explorations are consistent with normally consolidated glacial recessional outwash deposits of the Marysville Sand Member and generally consist of the following. • Loose to medium dense sand with variable silt and silt with variable sand content in the upper 5 to 7%2 feet.Soil mottling was observed in some of the samples collected in this depth range. • From about 5 to 7%feet down to about 15 to 17%feet, the outwash generally consists of medium dense to very dense gravelly sand to sandy gravel with trace to some silt. • From about 15 to 17% feet to the maximum depth explored at 60 feet below grade, the outwash generally consists of loose to medium dense sand with trace to some silt. Page 18 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants Volume 3, Section 3.3.6 of the 2014 DOE Manual includes provisions for the determination of initial and design saturated hydraulic conductivities for receptor soils based on 1) Large-Scale Pilot Infiltration Tests, 2) Small-Scale Pilot Infiltration Tests, and 3) by means of the Soil Grain Size Analyses Method. We completed our evaluation of the design infiltration rate using the Soil Grain Size Analysis Method based on test results of soil samples collected in ZGA's explorations.Grain size analysis test results are presented in Appendix B of this report. The Design Infiltration Rates presented in the table below include the following correction factors in accordance with Volume 3, Section 3.3.6 of the 2014 DOE Manual. • Site Variability and number of locations tested (CFv) =0.5 • Test Method (CFt) = 0.4 • Degree of influent control to prevent siltation and bio-buildup (CFm) =0.9 Summary of Grain Size Analysis Tests Relative to Stormwater Infiltration Sample Initial(unfactored) Sample Design Infiltration Exploration Depth Soil Formation Saturated Hydraulic Number Rate'(in/hr) (ft) Conductivity(in/hr) B-1 S-3 7% Marysville Sand Member 20.2 3.6 B-1 S-4 10 Marysville Sand Member 37.1 6.7 B-1 S-5 10 Marysville Sand Member 19.3 3.5 B-2 S-2 5 Marysville Sand Member 3.8 0.7 B-2 S-3 7/ Marysville Sand Member 12.5 2.3 B-2 S-4 10 Marysville Sand Member 15.6 2.8 B-2 S-5 15 Marysville Sand Member 14.7 2.6 B-3 S-2 5 Marysville Sand Member 39.9 7.2 B-3 S-3 7/ Marysville Sand Member 2.0 0.4 B-3 S-4 10 Marysville Sand Member 4.4 0.8 B-3 S-5 15 Marysville Sand Member 4.5 0.8 B-4 S-2 5 Marysville Sand Member 11.9 2.2 B-4 S-3 7/ Marysville Sand Member 8.3 1.5 B-4 S-5 15 Marysville Sand Member 28.4 5.1 1. Includes Correction Factors: CFv=0.5,CFt=0.4,and CFm=0.9 Based on our subsurface explorations, laboratory testing, and the calculated infiltration rates presented in the table above, we recommend a design infiltration rate of 2.6 inches per hour for a stormwater gallery located in the east-central portion of the western parcel with a bottom of gallery elevation of 122.5 feet. For an infiltration pond located in the western portion of the eastern parcel with a bottom of pond elevation of 124 feet, we recommend a design infiltration rate of 1.5 inches per hour.The design infiltration rate for the Page 19 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants pond may be increased to 2.6 inches per hour if the bottom of the pond is lowered to an elevation less than 120.5 feet. 3.14.2 Seasonal High Groundwater ZGA monitored groundwater levels on a roughly monthly basis in observation wells installed in borings 13- 1 through B-3 between 17 October 2023 and 26 March 2024. Based on our measurements, we recommend a seasonal high groundwater elevation of 117.5 feet. 3.14.3 Infiltration System Overflow Considerations The design of infiltration system is based on a number of design parameters with variable uncertainties. Therefore, we recommend that infiltration systems include an overflow when permitted by code to reduce the potential for water in the system from rising above the top of the system storage aggregate or the bottom of the base course for the parking lot pavement section during periods of unusually high or intense precipitation. 3.14.4 Water Quality Treatment Characteristics of Receptor Soils Soil requirements for water quality treatment considerations are presented under Site Suitability Criteria (SSC)4 and 6 in Volume 3,Section 3.3.7 of the 2014 DOE Manual. Laboratory test results relative to water quality treatment characteristics are summarized below. Analytical laboratory test results are presented in Appendix 8 of this report. 3.14.4.1 Organic Content SSC-6 requires a minimum organic content of 1 percent for treatment facilities. Organic content tests completed on three samples collected from borings B-1, B-2, and B-4 (at depths of about 5, 7%, and 10 feet below grade) had organic contents ranging from 1.1 to 1.6 percent by weight with an average of about 1.4 percent by weight. 3.14.4.2 Cation Exchange Capacity SSC-6 requires a minimum Cation Exchange Capacity (CEC) of 5 milliequivalents/100grams dry soil for treatment facilities. CEC tests completed on three samples collected from borings B-1, B-2, and B-4 (at depths of about 5, 7%, and 10 feet below grade) had CEC values ranging from 5.8 to 6.5 milliequivalents/100grams dry soil with an average of about 6.2 milliequivalents/100grams dry soil. It should be noted that SSC-6 states that lower CEC(less than 5 milliequivalents/100grams dry soil) may be considered if it is based on a soil loading capacity determination for the target pollutants that is accepted by the local jurisdiction. 3.15 Pavements 3.15.1 Asphalt Pavements The following pavement sections represent our minimum recommendations for an average level of performance during a 20-year design life; therefore, an average level of maintenance will likely be required. A 20-year pavement life typically assumes that an overlay will be placed after about 12 years. Page 20 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants Thicker asphalt, base, and subbase courses would offer better long-term performance, but would cost more initially. Conversely, thinner courses would be more susceptible to "alligator" cracking and other failure modes. As such, pavement design can be considered a compromise between a high initial cost and low maintenance costs versus a low initial cost and higher maintenance costs. The native subgrade soils are anticipated to consist of a mixture of sand with varying portions of silt. Based on our experience with similar soils, we have estimated a California Bearing Ration (CBR) value of 15 percent for this project. No traffic loading was provided for this project. We have assumed relatively low traffic volumes. We recommend that the upper 12 inches of pavement subgrades be prepared in accordance with the recommendations presented in the Subgrade Preparation section of this report. We recommend that the crushed aggregate base course conform to Section 9-03.9(3) of the WSDOT Standard Specifications. All base material should be compacted to at least 95 percent of the maximum dry density determined in accordance with ASTM: D 1557. 3.15.1.1 Asphalt Pavement Recommendations For light duty pavements(parking stall areas),we recommend 2%inches of asphalt concrete over 4 inches of crushed rock base course. For heavy duty pavements (main access roads, truck delivery routes, etc.), we recommend 3%inches of asphalt concrete over 6 inches of crushed rock base course. We recommend that the asphalt concrete conform to Section 9-02.1(4) for PG 58-22 or PG 64-22, Performance Graded Asphalt Binder as presented in the 2022 WSDOT Standard Specifications. We also recommend that the gradation of the asphalt aggregate conform to the aggregate gradation control points for%-inch mixes as presented in Section 9-03.8(6), HMA Proportions of Materials. We recommend that asphalt be compacted to a minimum of 92 percent and a maximum of 96 percent of the theoretical maximum density. 3.15.2 Concrete Pavements Concrete pavement design recommendations are based on an assumed modulus of rupture of 600 psi and a minimum compressive strength of 4,000 psi for the concrete. For light duty pavements,we recommend 5 inches of concrete over 4 inches of crushed aggregate base. For heavy duty pavements,we recommend 6 inches of concrete over 4 inches of crushed aggregate base. We recommend that concrete pavements be lightly reinforced with 6x6-W2.OxW2.0 welded wire fabric or equivalent to control cracking and have relatively closely spaced control joints on the order of 10 to 12 feet. We recommend that contraction joints be cut before the development of tensile stresses in the concrete. We recommend that the contraction joints be cut to a minimum depth of one inch. We further recommend that loading dock and trash enclosure pavements be reinforced with#4 bars at 15 inches each direction. 4.0 CLOSURE The analysis and recommendations presented in this report are based, in part, on the explorations completed for this study. The number, location, and depth of the explorations were completed within the constraints of budget and site access so as to yield the information for our environmental scope and Page 21 Arlington Commercial Development ZipperGeo ZGA Project No. 2760.01 March 28, 2024 Geoprofessional Consultants to formulate our geotechnical recommendations. Project plans were in the preliminary stage at the time this report was prepared. We therefore recommend that ZGA be provided an opportunity to review the final plans and specifications when they become available in order to assess that the recommendations and design considerations presented in this report have been properly interpreted and implemented into the project design. The performance of earthwork, structural fill,foundations, and pavements depend greatly on proper site preparation and construction procedures. We recommend that Zipper Geo Associates, LLC be retained to provide geotechnical engineering services during the earthwork-related construction phases of the project. If variations in subsurface conditions are observed at that time,a qualified geotechnical engineer could provide additional geotechnical recommendations to the contractor and design team in a timely manner as the project construction progresses. This report has been prepared for the exclusive use of Wet Rabbit, LLC, and their agents, for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either express or implied, are intended or made. Site safety and excavation support are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Zipper Geo Associates, LLC reviews the changes and either verifies or modifies the conclusions of this report in writing. Page 22 \So W -mow LEGEND "_ Q RIM=3038 � 129 WHITE LINE o �B-1 BORING NUMBER AND 12"IN EIE-11 .8 204TH ST NEB 3w a APPROXIMATE LOCATION. 12"OUT E W IE=111.98 7�o +LINE" 4 I N89°4639"E 770.80'-P,SP(771.00'-M,R2) 11 40.60'-R3) _ N CPT-1 CPT NUMBER AND 330.03' -SS R SS_ YELLOW LINE o EXTRUDED CURB ¢ S SS SS SS SS SS SS SS ASS- APPROXIMATE LOCATION. T T T 3 b SITE BENCHMARK SSMH N m WHITE LINE 1?9 -� N MAG NAIL&WASHER RIM=131.53 N I v p EL=129.56 12"IN E IE=113.15 A 12"OUT IE=113.05 ry ACCESS ij S89°46'39"W 91.7T 3 IC \ z Oti Q TELEPHONE 18"CPP IE=126.55 .9 13 VAULT ` \ 'ARLINGTON PLAZA" / I MONUMENT SIGN CURVE RADIUS DELTA ANGLE ARC LENGTH j/�2 �127 Q �f C1 2217.00' 2°36'32" 100.95' ST.STA.923+86.66-Ri 7.77' WB 18 C2 25.00' 87°22'U7" 38.12' MONUMENTSIGN ��// 10.0'PUD EASEMENT C3 500:00: 90'51'4 618 3 PER AFN 830414/1147C4 500.00' 70°51'40" 618.38'75' DRAINAGE ROW DITCH 21 20.0'DRAINAGE EASEMENT \PER AFN 8909205003 FOUND REBAR&CAP LOT 1 w I I I OD p / "AXIS 45502 NUMBERS" 3 OTHER \ U O ®� PARCEL I L� LSNUMBERS" a p 33,033 SF a ¢ O, o 0 o e \,y°\��B DRAINAGE LOT 2 \ I�I I �\ DITCH BOUNDARY LINE ADJUSTMENT \ ; AFN 9805065005 CO \ / r.� NC \ WALL \ \ a 13 ¢ 16.1' N 14.0' ( 7So LANE 1953 LLC \ 8.4' \ \WHEEL _ I CONC WALL - I \�\\\ / ROW L STOP(TYP) - VARIES I CPT-1 BUILDING cl V/BLACK E \ \\\ IV \ / P N #7530 3 I GRASS/BLACKBERRIES �' 0" \ T; �2\\\ ry�G� ti° E I 91 CS.STA.921+96.68-Ri /I 1 0' \ .Ig � FF=130.46 j P " 25.1' 12.8' 10.3' " m X \\ DRAINAGE p' rj ACONC WALL"-' DITCH / / SSMH / 0 SS RIM=130.14 ®B-4 6'.PVCOU NIE�24.34 PARCEL II I I I 75' r 30' 33,085 SF ROW ®B-L / ' ' 131 I U�9 PARCEL B vS 18"CMP IE=129.95 BLA PLN 899 / AFN 20 2203 1 05003 J589°a6'39"W 117.70'-C,118.1a'-R I 132 - - - -133 -134- \ VACANT LOT / GRASS/BLACKBERRIES �Q / ��'�O=!�, ••O FOUND REBAR&CAP °LS 12716" 1 1 \ B-3 �'eL 23 VIP I DOWN 1.0' � ® 1UNABLE TO FIND 35� \ NEXT SSMH NORTH 50 0 25 50 _13 l 132 �7B F4j 9 POSSIBLY PAVED OVER FOUND REBAR"LS&CAP I 6 -137 C,\ 3g6 S14p F 1 S��� ��� O / SCALE IN FEET "LS 12716" a.a'w �y °Nc wqC �9846, " E7 :a�J�Ci? / Proposed Arlington Commercial Development F NOF POWER VAULT O � / Q� o�v 7530 204th Street NE L FOUND REBAR&CAP " �^/\I`� Q/ "AXIS 45502&3OTHER Arlington,Washington JR'd I h / LS NUMBERS"00, 0.3,SW PARCEL A � � �� � SITE AND EXPLORATION PLAN Ico LOT A I M1 ... BLA PLN 21 ] Date:March 2024 Job No. 2760.01 Zipper Geo Associates,LLC FIGURE 19019 36th Ave.W.,Suite E REFERENCE:ALTA/NSPS LAND TITLE SURVEY FOR LEAN GOAT VENTURES, LLC, PREPARED BY HARMSEN, REVISED NOVEMBER 14, 2023. Lynnwood,WA SHT.1 of 1 APPENDIX A SUBSURFACE EXPLORATION PROCEDURES AND LOGS APPENDIX A SUBSURFACE EXPLORATION PROCEDURES AND LOGS Subsurface Exploration Description Our subsurface evaluation for this project included advancing four borings(13-1 through B-4)and one cone penetrometer test(CPT-1),completed in October 2023.The approximate locations of the explorations are presented on the Site and Exploration Plan, Figure 1. Exploration locations and ground surface elevations were provided to ZGA by Pacland based on a site-specific survey completed by Hamsen. Soil Borings The borings were advanced using a track-mounted drill rig operated by a local drilling company(Holocene Drill, Inc.)working under subcontract to ZGA. The borings were advanced using hollow stem auger drilling methods. A geologist from our firm continuously observed the borings, logged the subsurface conditions encountered, and obtained representative soil samples. All samples were stored in moisture-tight containers and transported to our laboratory for further evaluation and testing. Samples were obtained by means of the Standard Penetration Test at 2.5-to 5-foot intervals throughout the drilling operation. The Standard Penetration Test (ASTM D 1586) procedure consists of driving a standard 2-inch outside diameter steel split spoon sampler 18 inches into the soil with a 140-pound hammer free falling 30 inches. The number of blows required to drive the sampler through each 6-inch interval is recorded, and the total number of blows struck during the final 12 inches is recorded as the Standard Penetration Resistance, or "blow count"(N value). If a total of 50 blows are struck within any 6-inch interval,the driving was stopped, and the blow count is recorded as 50 blows for the actual penetration distance. The resulting Standard Penetration Resistance values indicate the relative density of granular soils and the relative consistency of cohesive soils. The enclosed boring logs describes the vertical sequence of soils and materials encountered in the borings, based primarily upon our field classifications. Where a soil contact was observed to be gradational, our logs indicate the average contact depth. Where a soil type changed between sample intervals,we inferred the contact depth. Our logs also graphically indicate the blow count, sample type, sample number, and approximate depth of each soil sample obtained from the borings. If groundwater was encountered,the approximate groundwater depth, and date of observation, are depicted on the logs. Groundwater monitoring well installations are also graphically indicated on the logs. Cone Penetrometer Test (CPT) One electric cone penetrometer probe was completed using a truck-mounted probe rig operated by an independent firm (In-Situ Engineering, Inc.)working under subcontract to ZGA. An engineer from our firm continuously observed the probes while electronic monitoring equipment in the probe rig automatically logged the subsurface conditions. After the probe was completed, the probe hole was backfilled with a bentonite slurry. Throughout the probing operation, soil and groundwater properties were measured at 5-centimeter depth intervals by means of the Cone Penetration Test (CPT) in general accordance with ASTM D3441. This testing procedure involves pushing a standard 1.5-inch diameter steel cone penetrometer into the soil with hydraulic rams. A cone penetrometer consists of a conical tip,a cylindrical sleeve,and a pressure transducer. As the penetrometer is pushed downward, the tip resistance, sleeve friction, and porewater pressure are measured electronically and plotted as a function of depth. Through interpretation, the resulting graphs can reveal soil types and groundwater levels, as well as the relative density of granular soils and the relative consistency of cohesive soils. The CPT exploration completed for this project also included measurements of soil shear wave velocity. The enclosed CPT graph presents the vertical plots of several soil properties and groundwater pressures measured by the cone penetrometer at each probe location. These graphs also depict the Standard Penetration Resistance (N60) corresponding to each test interval, based on published conversion charts. EXPLANATION OF EXPLORATION LOGS SOIL DESCRIPTION: Soil descriptions presented on the borings logs are based on visual observations. Soil descriptions include density (coarse- grained soils) or consistency (fine-grained soils), moisture, color, major soil type, and grain size modifiers and should not be interpreted to suggest laboratory or field testing unless indicated on the logs. Soil descriptions include the following: Density/consistency, moisture, color,grain size modifier (adjective implying 31-49 percent), major soil type (CAPITALIZED implying 50+ percent), minor grain size modifier(some implying 6-12 percent, with implying 13-30 percent, and trace implying 0-5 percent), descriptive modifiers (i.e. roots, fill debris, cemented, etc.), and interpreted general geologic description. Descriptions may also include comments describing geologic properties such as dilatancy,toughness,structure,plasticity,and angularity of coarse-grained particles. Additional information regarding geologic properties is presented in the report text as applicable. DENSITY/CONSISTENCY: Soil density/consistency in borings is related to the blow count number in blows per foot using the sampling method indicated on the logs.Soil density/consistency in test pits is related to a"Field Test"as described below. Soil consistency in test pits or borings may be augmented by field Torvane or Pocket Penetrometer testing. Coarse-Grained Soils Density SPT Field Test Descriptor #blows/ft Very Loose 0-4 Easily penetrated with'/z-inch steel rod pushed by hand. Loose 5—10 Difficult to penetrate with'/2-inch steel rod pushed by hand. ..................................................................................................................:.......................................................................................................................................................................................................................................................................................................... Medium 11 —30 Easily penetrated a foot with'/,inch steel rod driven with 5-lb hammer. Dense Dense 31 —50 Difficult to penetrate a foot with''/,inch steel rod driven with 5-lb hammer. Very Dense >50 Penetrated only a few inches with''/2-inch steel rod driven with 5-lb hammer. Fine-Grained Soils Torvane Pocket Penetrometer Consistency SPT Undrained Unconfined Field Test Descriptor (#blows/ft) shear Compressive strength(tsf) Strength (tsf) Very Soft 0-2 <0.125 <0.25 Easily penetrates several inches by thumb. ......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... Soft 3-4 0.125—0.25 0.25—0.5 Easily penetrates one inch by thumb. ......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... Medium Stiff 5-8 0.25—0.5 1 0.5—1.0 Penetrated over inch by thumb with moderate effort. ......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... Stiff 9—15 0.5—1.0 1.0—2.0 Indented by thumb but penetrated only with great effort. ....................................................................:.......................................................,................................................................:.........................................................................:..................................................................................................................................................................................................................................................................................................... Very Stiff 16—30 1.0—2.0 2.0—4.0 Readily indented by thumbnail. ........................................................................................................................................................................................................................................................................................................................ .... .. ....................................................................................................................................................... ................................................................................... Hard >30 >2.0 >4.0 Indented by thumbnail with difficult effort. MOISTURE Descriptor Field Test Dry Absence of moisture,dusty,dry to the touch. ..................................................................................................................................................................................................................................................:.................................................................................................................................................................................................................................................. Damp : Too low to achieve compaction ..................................................................................................................................................................................................................................................e.................................................................................................................................................................................................................................................. Moist Appears near optimum moisture content for compaction ..................................................................................................................................................................................................................................................:.................................................................................................................................................................................................................................................. Wet Too wet to achieve compaction ..................................................................................................................................................................................................................................................:.................................................................................................................................................................................................................................................. Saturated Below the groundwater table,visible free moisture. MAJOR SOIL TYPE: Coarse-grained soils with over 50%of the material retained on the U.S.No.200 sieve. Coarse-grained soils include boulders, cobbles,gravels and sands. Fine-grained soils with over 50%of the material passing the U.S.No.200 sieve. Fine-grained soils include silts and clays. GRAIN SIZE Descriptor Sieve Size Grain Size Boulder >12" >12" ...............................................................................................................................................................[.....................................................................................................................................................................€............................................................................................................................................................... Cobble 3—12" 3—12" ...............................................................................................................................................................[.....................................................................................................................................................................€............................................................................................................................................................... Gravel 3"—#4 3"—0.19" ...............................................................................................................................................................:.....................................................................................................................................................................:............................................................................................................................................................... Sand >#4—#200 <0.19"—>0.0029" ..............................................................................................................................................................:....................................................................................................................................................................:...............................................................<........................................................................................... Silt/Clay Passing#200 0.0029" GRAIN SIZE MODIFIERS Descriptor Approximate Percentage Trace 0-5 ............................................................................................................................................................._..................................................................................................................................................................... Some 6—12 ...............................................................................................................................................................:.................................................................................................................................................................... With 13—30 ,sandy,gravelly).............................................................................3.1..._..50................................................................... Adjective(silty,clayey Boring Location: See Site and Exploration Plan Drilling Company: Holocene Bore Hole Dia.:8-inch Top Elevation: 127.62 Feet Drilling Method: Hollow Stem Auger Hammer Type: Automatic B-1 Date Drilled: 10/12/2023 Drill Rig: Diedrich D-50 Logged by KRN SOIL DESCRIPTION PENETRATION RESISTANCE(blows/foot) U) U E J Standard Penetration Test o The stratification lines represent the approximate boundaries o Hammer Weight and Drop: U N between soil types. The transition may be gradual. Refer to E Q report text and appendices for additional information. A co ° ° U 0 20 40 60 m Approximately 2-inches of asphalt over moist,brown,SAND with gravel to gravelly SAND,trace silt.(Marysville Sand + I IIIIIIIII IIIIIIIII Member) h l l II IIIIIIIII IIIII Very loose, moist,brown and mottled gray,silty SAND to S-1 12" rrrrrr r/1�I 11 I f-I I T���7777..7.. 3 SILT,some sand.No odors,no staining, PID<1 ppmv. `'III L LLLLLLL i IIIIIIIII Illllllil IIIIIIIII iillii111 111111ii1 Iiillilii 5 Dense,moist,gray, mottled,SILT,some sand,some roots.No S 2 T 1$„ 0I 44 cec odors,no staining, PID<1 ppmv. 11 h hhl I I I-I + oRG Grades to SAND,some gravel. . IIIIII II1I11iil Iiillilii IIII II IIIIIIIII IIIIIIII S-3 12" T T r r F- II I I I I T—1-1 T 7 7 7�._.. 38 GSA Dense,moist,brown to gray,gravelly SAND,some silt. I I� r I�1 1 1 1 11 I I� 11 I I I 1111LLL L L L L j L LLL LLALL L A I I IIIIIIIII IIIIIIIII IIIIIIIII II111Iiil Iiillilii 10 Dense,moist,brown to gray,gravelly SAND,some silt.No S-4 T 9„ 1 1 34 GSA odors,no staining, PID<1 ppmv. 11 r hh I i III IIIIIIIII IIII IIII r rrrri-rr rl—I I i t_f_I 17—f77�f�t�I� IIIIIIII IIIIIIIII IIIIIII . ' IIIIIIII IIIIIIIII IIIII T T r r T-r r r IIIIIIII IIIIIIIII IIIII -L LLLLLL .LLLLLLLJJ J JJJ1 1.1. IIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII 15 IIIIIIII IIIIIIIII IIIIIIIII Dense,moist,brown to golden brown,gravelly SAND,some S 5 T 9„ 43 GSA silt. No odors,no staining,PID<1 ppmv. 11 I 1� t1 ���� � -4-444-4++ IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIII IIIIIIIII IIIIIIIII •: •:: TTrrrrrrr rrl I I I I-i 1 7--1-1r-T7r-f7 IIIIIIIII IIIIIIIII Till IIII �:•' 1111LLLLL L.LI I 1 I I_I I L�JJJJLJ.1. IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII 20 Medium dense,moist,golden brown,SAND,trace to some T silt. No odors,no staining,PID<1 ppmv. S-8 11 18° :`;= *T-� 11 : +++-L L� LLLLLLI—I� ����4L L 44 IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII r rl—I :' IIIIIIIII IIIIIIIII IIIIIIIII ' IIIIIIIII IIIIIIIII IIII TTTTT-T-_rr F-7 I I I i—I 1 rI,I.,I.7I7I777 7 ':•' IIIIIIIII IIIIIIIII IIIIIIIII "''" IIIIIIIII IIIIIIIII LLLIIIIII ':•' IIIIIIIII IIIIIIIII IIIIIIIII : IIIIIIIII IIIIIIIII IIIIIIII 25 — ii111ii11 1111ii1 1ii11iiii SAMPLE LEGEND GROUNDWATER LEGEND %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand O %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonite Plastic Limit Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis V Groundwater level at Arlington, WA time of drilling(ATD)or 200W=200 Wash Analysis N on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test N measurement. Z i p pe rG eo BORING B�1 Att.=Atterberq Limits Geoprofessional Consultants LOG. 19019 36th Ave.W,Suite E Lynnwood,WA Page 1 of 2 Boring Location: See Site and Exploration Plan Drilling Company: Holocene Bore Hole Dia.:8-inch Top Elevation: 127.62 Feet Drilling Method: Hollow Stem Auger Hammer Type: Automatic B-1 Date Drilled: 10/12/2023 Drill Rig: Diedrich D-50 Logged by KRN SOIL DESCRIPTION PENETRATION RESISTANCE(blows/foot) rn U E J Standard Penetration Test o The stratification lines represent the approximate boundaries o Hammer Weight and Drop: U N between soil types. The transition may be gradual. Refer to £Q report text and appendices for additional information. in U ° ° U 0 20 40 60 m 25 S-7 18 16 •I -7T-T TTTTTri_ _ Medium dense,saturated,golden brown,SAND,trace to IL.._I J J_�... some silt. No odors,no staining, PID<1 ppmv. — l TTTTTTTTT — it IIIIIIIII IIIIIIIII �i.iii"L" — II IIIIIIIII IIIIIIIII — IIII - I IIIIIIIII IIIIIIIII — I IIIIIIIII IIIIIIIII 30 Loose,saturated,golden brown,SAND,trace to some silt. -11T777777 TTTTTTTT7 ' i ... - .. .. IIIIIIIII IIIIIIIII Boring completed at approximately 31.5 feet.Groundwater I I .-. . -.. I ILI JI JI JI I I I T T.T I I LI LI LILI. was encountered at approximately 25 feet below ground surface at time of drilling• gY g Ecology Well Tag ID BPX 514. Illlllill IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII 35 IIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII ri->-rl-m7 -7-1-I-777777 TTTTTTT T T IIIIIIIII IIIIIIIII IIIIIIIII L. III. _II _iJJJ1L Ll LLL.T- IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII LLLLLLIJJ JJJJ J-11-11.1 11..1 L L L L L..L... IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII IIIIIIIII 40 11 Hiii l HI IIII liillliii iillliill iillllil liillliii iillliill IIIIIIIII liillliii rr1 1 1-I-4-I I 77TTrt�7 7 7 Y r-rTTrrrr L.L1 I I_L_L_1 I JJ.J J J J 1 J -L L L L.L.L. IIIIIIIII IIIIIIII IIIIII IIIIIIIII IIIIIIII IIIIII -4- I--I- -I---4-4-44.1-4 +T F F IIIIIIIII IIIIIIIII IIIIIIIII 45 IIIIIIIII IIIIIIIII IIIIIIIII III IIIIIIII III rrrrl-�r-1-1 -1-1-1rtrt7rtrtrt TrttTTrtrrfi IIIIIIIII IIIIIIIII liillliii l l l l l l .-1�T T�I�1 7 -T-1 I r r r.r.r. IIII i iillll iii L.LII JJJJJJIJ LLLL.L.L. IIII I IIIII � I '.. '.. IIIIII IIII I III I '.. '.. IIIIII t-4-1-4-...1-...1-... ... ... III 50 SAMPLE LEGEND GROUNDWATER LEGEND O %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand O %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonite Plastic Limit Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis V Groundwater level at Arlington, WA time of drilling(ATD)or 200W=200 Wash Analysis N on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test N measurement. Att.=Atterberq Limits Z i p pe rG eo BORING B_� Geoprofessional Consultants LOG. 19019 36th Ave.W,Suite E Lynnwood,WA Page 2 of 2 Boring Location: See Site and Exploration Plan Drilling Company: Holocene Bore Hole Dia.:8-inch Top Elevation: 129.79 Feet Drilling Method: Hollow Stem Auger Hammer Type: Automatic B-2 Date Drilled: 10/12/2023 Drill Rig: Diedrich D-50 Logged by: KRN SOIL DESCRIPTION PENETRATION RESISTANCE (blows/foot) iu U) L C Standard Penetration Test 01 S The stratification lines represent the approximate boundaries z 0 o v 0 2 o 0 Hammer Weight and Drop: a) between soil types. The transition may be gradual. Refer to s Q N M report text and appendices for additional information. to ° O 0 0 20 40 60 m -0- Approximately 2-inches of asphalt over moist,brown SAND, 1 with gravel to gravelly SAND,trace silt.(Marysville Sand Member) IT 1711-11 Loose,moist,dark brown,silty SAND to sandy SILT,some T - fine roots.No odors,no staining,PID<1 ppmv. S-1 11 181 �� I I ( $ Grades to brown,decreasing roots,trace fine gravel. Medium dense,moist,brown,silty SAND,trace gravel,trace s-z 18 Q 1z GSA roots.No odors,no staining,PID<1 ppmv. — — Very dense,moist,light brown to brown,gravelly SAND,with O . GSA silt.No odors,no staining,PID<1 ppmv. s-3 1s ss cec 1 � I I ORG 10 Very dense,moist,brown to dark brown,GRAVEL,with sand S-4 I 18 ( I 63 GSA and silt.No odors,no staining,PID<1 ppmv. 1 M r( J_W 15 I I I � Dense,moist,brown, GRAVEL,with sand and silt.No odors, S-5 18" O 1 11 1 34 GSA no staining,PID<1 ppmv. ( ( L 1LI�+-tII ,. it i I I �IIIII III ( �� III I 20 Medium dense,moist,golden brown,SAND with trace to S-6 18" l 13 some silt.No odors,no staining,PID<1 ppmv. 25 SAMPLE LEGEND GROUNDWATER LEGEND 0 %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand O %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonite Plastic Limit i e d Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis V Groundwater level at Arlington, WA time of drilling(ATD)or 20oW=200 Wash Analysis N on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test N measurement. ZipperGeo BORING Att.=Atterberq Limits B-2 Geoprofessional Consultants LOG` 19019 36th Ave.W,Suite E Lynnwood,WA Page 1 of 2 Boring Location: See Site and Exploration Plan Drilling Company: Holocene Bore Hole Dia.:8-inch Top Elevation: 129.79 Feet Drilling Method: Hollow Stem Auger Hammer Type: Automatic B-2 Date Drilled: 10/12/2023 Drill Rig: Diedrich D-50 Logged by: KRN SOIL DESCRIPTION PENETRATION RESISTANCE (blows/foot) iu U) L C j Standard Penetration Test of S The stratification lines represent the approximate boundaries z 0 o 0 2 o 0 Hammer Weight and Drop: a) between soil types. The transition may be gradual. Refer to E Q N M report text and appendices for additional information. to ° O 0 0 20 40 60 m 25 Medium dense,wet to saturated,golden brown,SAND with trace to some silt.No odors,no staining,PID<1 ppmv. s-7 F18" ( tt 30 Medium dense,saturated,golden brown,SAND,trace to some silt.No odors,no staining,PID<1 ppmv. s-a is I I tv I T --t 35 = HHH zo Medium dense,saturated,golden brown,SAND,trace to . .. some silt.No odors,no staining,PID<1 ppmv. s-s 18 Boring completed at approximately 36.5 feet.Groundwater — was encountered at approximately 30 feet below ground III surface at time of drilling.Ecology Well Tag ID BPX 515. t 40 iii �lllllll �lll i � lli 45 it Lii -L 1 41 50 SAMPLE LEGEND GROUNDWATER LEGEND 0 %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand O %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonite Plastic Limit i e d Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis VGroundwater level at Arlington, WA time of drilling(ATD)or 20oW=200 Wash Analysis N on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test N measurement. ZipperGeo BORING Att.=Atterberq Limits B-2 Geoprofessional Consultants LOB'`V 19019 36th Ave.W,Suite E Lynnwood,WA Page 2 of 2 Boring Location: See Site and Exploration Plan Drilling Company: Holocene Bore Hole Dia.:8-inch Top Elevation: 132.00 Feet Drilling Method: Hollow Stem Auger Hammer Tvpe: Automatic B-3 Date Drilled: 10/12/2023 Drill Rig: Diedrich D-50 Logged by: KRN SOIL DESCRIPTION PENETRATION RESISTANCE (blows/foot) iu U) L C Standard Penetration Test o� S The stratification lines represent the approximate boundaries z 0 o 0 2 o 0 Hammer Weight and Drop: a) between soil types. The transition may be gradual. Refer to E Q N M report text and appendices for additional information. to ° O 0 0 20 40 60 m -0- Grass over approximately 3 inches of moist,brown,SAND 1 with silt,abundant grass roots.(Marysville Sand member) 11-M - U T " Loose,moist,brown,SAND with silt to silty SAND,some fine - roots.No odors,no staining,PID<1 ppmv. S-t 1811 , ( s II . 5 I I Medium dense,moist,dark brown,SAND with gravel,some s-z to �— z� GSA silt.No odors,no staining,PID<1 ppmv. — — Dense,moist to wet,brown,sandy SILT,trace gravel.No S-3 s �� as 'SA odors,no staining,PID<1 ppmv. - H�j IL� II 10 Dense,moist to wet,brown,silty SAND,with gravel.No odors, s-a I tz° L.. ( ( I as GSA no staining,PID<1 ppmv. 1 T� r( Grades to gravelly SAND,some silt. 15 Very dense,wet,brown,silty SAND some gravel.No odors, s-5 I s^ 1 82 GSA no staining,PID<1 ppmv. 1 - Q � � IIII 1II11I � IL_ 111I1III IIIII Ali... 20 Very dense,wet,brown, SAND with silt,decreasing fines to S-s T t$„ 111 + 1 some silt.No odors,no staining,PID<1 ppmv. 11 .tfl iI �1 I 125- SAMPLE LEGEND GROUNDWATER LEGEND Q %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand O %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonite Plastic Limit i e d Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis V Groundwater level at Arlington, WA time of drilling(ATD)or 20oW=200 Wash Analysis N on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test N measurement. ZipperGeo BORING Att.=Atterberq Limits B-3 Geoprofessional Consultants LOG` 19019 36th Ave.W,Suite E Lynnwood,WA Page 1 of 2 Boring Location: See Site and Exploration Plan Drilling Company: Holocene Bore Hole Dia.:8-inch Top Elevation: 132.00 Feet Drilling Method: Hollow Stem Auger Hammer Tvpe: Automatic B-3 Date Drilled: 10/12/2023 Drill Rig: Diedrich D-50 Logged by: KRN SOIL DESCRIPTION PENETRATION RESISTANCE (blows/foot) iu U) L C Standard Penetration Test of S The stratification lines represent the approximate boundaries z 0 o 0 2 o 0 Hammer Weight and Drop: a) between soil types. The transition may be gradual. Refer to E Q N M report text and appendices for additional information. to ° O 0 0 20 40 60 m 25 — Medium dense,wet, brown,SAND,trace to some silt.No odors,no staining,PID<1 ppmv. S-7 F18- 22 _ : i � I7 IIII IIII 30 Medium dense,saturated,brown,SAND,trace to some silt. s-8 18 .:: � zz No odors,no staining,PID<1 ppmv. - IN Itt4I IIH+ l 1 �j1+I 1-11 35 Medium dense,saturated,brown,SAND,trace to some silt. 1� No odors,no staining,PID<1 ppmv. Ifltj .::•.::•.::•:,. I I III I Boring completed at approximately 36.5 feet.Groundwater — was encountered at approximately 30 feet below ground L I III surface at time of drilling.Ecology Well Tag ID BPX 516. 40 IIIIIII iii �111llll �lll i � lli 45 it Lii -L 1 41 JO SAMPLE LEGEND GROUNDWATER LEGEND 0 %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand O %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonite Plastic Limit i e d Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis V Groundwater level at Arlington, WA time of drilling(ATD)or 20oW=200 Wash Analysis N on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test N measurement. ZipperGeo BORING Att.=Atterberq Limits B-3 Geoprofessional Consultants LOB'`V 19019 36th Ave.W,Suite E Lynnwood,WA Page 2 of 2 Boring Location: See Site and Exploration Plan Drilling Company: Holocene Bore Hole Dia.:8-inch Top Elevation: 130.61 Feet Drilling Method: Hollow Stem Auger Hammer Type: Automatic B-4 Date Drilled: 10/12/2023 Drill Rig: Diedrich D-50 Logged by: KRN SOIL DESCRIPTION PENETRATION RESISTANCE (blows/foot) iu U) L C Standard Penetration Test o� S The stratification lines represent the approximate boundaries z 0 o 0 2 o 0 Hammer Weight and Drop: a) between soil types. The transition may be gradual. Refer to E Q N M report text and appendices for additional information. to ° O 0 0 20 40 60 m -0— Grass over approximately 4 inches of moist,brown,SAND with silt,abundant roots.(Marysville Sand Member) I Loose,moist,brown,SAND,with to some gravel,some silt, 1T _ "s-1 � 18^ s trace roots.No odors,no staining,PID<1 ppmv. III .... I I TTT III illII 5 thill I I Loose,moist,brown,SAND,with silt,trace gravel. No odors, s-z 1a" ILI 10 GSA no staining,PID<1 ppmv. — Dense,moist,dark brown,silty SAND,trace gravel. No odors, S-3 18^ I 41 GSA no staining,PID<1 ppmv. 10 Dense,moist,light brown,gravelly SAND,some silt.No odors, I GSA CEC no staining,PID<1 ppmv. s-a I s I+ ( ( L... I a� ORG 1 ORG i 15 Dense,moist,light brown,gravelly SAND to sandy GRAVEL. S-s 12^ I 35 No odors,no staining,PID<1 ppmv. II i L it Il � I L Il . � � � � i 20 �i Medium dense,moist,light brown,SAND with gravel,trace T s-s 1z^ z� silt.No odors,no staining,PID<1 ppmv. I Q j �_ im fi 25 SAMPLE LEGEND GROUNDWATER LEGEND 0 %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand O %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonite Plastic Limit i e d Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis VGroundwater level at Arlington, WA time of drilling(ATD)or 20oW=200 Wash Analysis N on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test N measurement. ZipperGeo BORING Att.=Atterberq Limits B-4 Geoprofessional Consultants LOG` 19019 36th Ave.W,Suite E Lynnwood,WA Page 1 of 2 Boring Location: See Site and Exploration Plan Drilling Company: Holocene Bore Hole Dia.:8-inch Top Elevation: 130.61 Feet Drilling Method: Hollow Stem Auger Hammer Type: Automatic B-4 Date Drilled: 10/12/2023 Drill Rig: Diedrich D-50 Logged by: KRN SOIL DESCRIPTION PENETRATION RESISTANCE (blows/foot) iu U) L C Standard Penetration Test of S The stratification lines represent the approximate boundaries z 0 o 0 2 o 0 Hammer Weight and Drop: a) between soil types. The transition may be gradual. Refer to E Q N M report text and appendices for additional information. to ° O 0 0 20 40 60 m 25 Medium dense,moist,light brown,SAND with gravel,trace silt.No odors,no staining,PID<1 ppmv. s-� �z° - to IIIII ' I O IIIIIII I7 IIIIII ) III 30 Medium dense,moist to wet,light brown,SAND with gravel, s_$ T 1$1, 24 trace silt.No odors,no staining,PID<1 ppmv. 1 i Boring completed at approximately 31.5 feet.Groundwater 4 l 1 --tI I+ was not encountered at time of drilling.Borehole backfilled with bentonite. 35 O ( LIB 40 IIII111 II11II1II llII �III i �.........III ICI' III wl 45 I `+ 1 4 ilII 1 I IIIIII� III 41 50 SAMPLE LEGEND GROUNDWATER LEGEND 0 %Fines(<0.075 mm) I2-inch O.D.split spoon sample ❑ Clean Sand O %Water(Moisture)Content 3-inch I.D.Shelby tube sample ® Bentonite Plastic Limit i e d Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing Arlington Commercial Development TESTING KEY ❑ Blank Casing 7530 204th Street NE GSA=Grain Size Analysis VGroundwater level at Arlington, WA time of drilling(ATD)or 20oW=200 Wash Analysis N on date of Date: March 2024 Project No.: 2760.01 Consol.=Consolidation Test N measurement. ZipperGeo BORING Att.=Atterberq Limits B-4 Geoprofessional Consultants LOB'`V 19019 36th Ave.W,Suite E Lynnwood,WA Page 2 of 2 CPT-01 CPT CONTRACTOR: In Situ Engineering OPERATOR:Forinash CUSTOMER:Zippergeo CONE ID:DDG1369 LOCATION:Arlington TEST DATE: 10/17/2023 9:30:24 AM JOB NUMBER:2760.01 PREDRILL:Oft BACKFILL:20%Slurry&Bentonite Chips SURFACE PATCH:Cold Patch Tip COR Sleeve Stress F.Ratio Pore Pressure SBT FR SPT (tsf) (tsf) N (psi) (RC 1983) (blows/ft) 0 0 600 0 9 0 9 -10 15 0 12 0 120 10 ............... . 1 t f t ----T 1 t t .... ........... ................. t t 1 t t . . . . . . . . . . . 20 ... ....... ..................... ..... .......... .... ....... ..........I.-.---. ............. ..... ..................... 30 . . . . . . . . . . . . ------------ -1 -1 -T -T r- --- ---------T---- ------------------------------------- Depth ............................ 40 ............... ............................... ..... .................... .... ........................ ..........------- .......................... ---- —-----------............... 50 ---- --------------- .......... . . . . . . . . . . 60 ---------- ................. -------------------- 70 TOTAL DEPTH:60.203 ft 1 sensitive fine grained 04 silty clay to clay 07 silty sand to sandy silt E10 gravelly sand to sand 02 organic material 0 5 clayey silt to silty clay 28 sand to silty sand 11 very stiff fine grained 03 clay 0 6 sandy silt to clayey silt 9 sand 0 12 sand to clayey sand *SBT/SPT CORRELATION: UBC-1 983 HOLE NUMBER: CPT-01 Depth 3.12ft I I I I Arrival 7.27mS Ref* - - -- --- - - - -------F-------+--------- Velocity. Depth 9.68ft I I I Arrival 17.66mS Ref 3.1 2ft -- -- - - --------------F-------------+------------- Velocity 577.77ft/S Depth 16.08ft I I I I Arrival 22.97mS Ref 9.68ft --+--- - - - --------------F-------------}------------- Velocity 11 81.03ft/S Depth 22.47ft I I I I Arrival 28.59mS Ref 16.08ft ------ Velocity 1127.77ft/S ------- ---- - - - - -- Depth 28.87ft I I I I Arrival 35.39mS Ref 22.47ft ______ Velocity 936.85ft/S Depth 35.43ft I I I I Arrival 42.42mS Ref 28.87ft - - - -- - + - - - -- ------ Velocity 930.45ft/S Depth 41.83ft I I I I Arrival 49.14mS Ref 35.43ft ______ Velocity 950.28ft/S Depth 48.39ft I I I I Arrival 55.43mS Ref 41.83ft ------ Velocity 1041.82ft/S Depth 54.79ft I I Arrival 61.17mS Ref 48.39ft ------ Velocity 1112.91ft/S Depth 60.20ft I Arrival 66.05mS Ref 54.79ft ----- - -- - ------ Velocity 1107.69ft/S 0 20 40 60 80 100 120 140 160 Time(mS) Hammer to Rod String Distance(ft):2.49 =Not Determined COMMENT: APPENDIX B LABORATORY TESTING PROCEDURES AND RESULTS LABORATORY TESTING PROCEDURES A series of laboratory tests were performed during the course of this study to evaluate the index and geotechnical engineering properties of the subsurface soils. Descriptions of the types of tests performed are given below. Visual Classification Samples recovered from the exploration locations were visually classified in the field during the exploration program. Representative portions of the samples were carefully packaged in moisture tight containers and transported to our laboratory where the field classifications were verified or modified as required. Visual classification was generally done in accordance with ASTM D2488. Visual soil classification includes evaluation of color, relative moisture content, soil type based upon grain size, and accessory soil types included in the sample. Soil classifications are presented on the exploration logs in Appendix A. Moisture Content Determinations Moisture content determinations were performed on representative samples obtained from the explorations to aid in identification and correlation of soil types. The determinations were made in general accordance with the test procedures described in ASTM D2216. Moisture contents are presented on the exploration logs in Appendix A. Grain Size Analysis A grain size analysis presents the range in diameter of soil particles that comprise a particular sample. Grain size analyses were performed on representative samples in general accordance with ASTM: D6913. The results of the grain size determinations for the samples were used in classification of the soils and are presented in this appendix. Cation Exchange Capacity Cation exchange capacity tests were completed on representative samples collected from prospective infiltration receptor soils by an independent analytical laboratory in accordance with the Washington State Department of Ecology SW-846 9081 test method. Test results are presented in this appendix. Organic Content Tests Organic content tests were completed on representative samples collected from prospective infiltration receptor soils by an independent analytical laboratory in accordance with ASTM D2974 test method.Test results are presented in this appendix. GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 Im W 60 Z M 1.— 50 Z W tU W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description Gravelly SAND, B-1 S-3 7.5 5.6 10.1 some silt PROJECT NO: 2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 Im 60 W Z M 50 Z W tU W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS LGRAVEL Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description Gravelly SAND, B-1 S-4 10 6.8 7.9 some silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates, LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 m 60 W Z 50 Z W tU W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS LGRAVEL Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description Gravelly SAND, B-1 S-5 15 6.1 9.1 some silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates, LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 m 60 W Z M 50 Z W tU W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS LGRAVEL Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description Silty SAND, B-2 S-2 5 16.3 48.1 trace grave PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates, LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commerical Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 Im 60 W Z M 50 Z W tU W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS LGRAVEL Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description Gravelly SAND, B-2 S-3 7.5 6.2 17.5 with silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates, LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4,, 3/8" 4 10 20 40 60 140 200 100 90 = 80 C9 W 70 Im 60 W Z LL 50 Z W U W 40 LU 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture(%) Fines(%) Description GRAVEL, with B-2 S-4 10 5.2 15.3 sand and silt PROJECT NO: 2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 1112" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 Im LU 60 Z M 1.— 50 Z W tU IW 40 W Ilk a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture(%) Fines(%) Description GRAVEL, with B-2 S-5 15 5.1 13.3 sand and silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 m 60 W Z 50 Z W tU W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS LGRAVEL Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description SAND, with B-3 S-2 5 5.4 6.8 gravel, some silt PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates, LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 Im 60 LU Z 1.— 50 Z LU tU Ili 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture(%) Fines(%) Description Sandy SILT, B-3 S-3 7.5 26.1 61.4 trace gravel PROJECT NO: 2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 C9 W 70 Im 60 W Z M 50 Z W U W 40 LU 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description B 3 S-4 10 17.6 35.9 Silty SAND, with gravel PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 m 60 W Z 50 Z W tU W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS LGRAVEL Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description Silty SAND, B-3 S-5 15 21.4 43.5 some gravel PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates, LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commerical Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 Im 60 W Z 50 Z W tU W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS LGRAVEL Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description SAND, with silt, B-4 S-2 5 14.7 23.8 trace gravel PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates, LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 m 60 W Z M 50 Z W tU W 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS LGRAVEL Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) Fines(%) Description Silty SAND, B-4 S-3 7.5 18.5 30.6 trace gravel PROJECT NO:2760.01 PROJECT NAME: Zipper Geo Associates, LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development GRAIN SIZE ANALYSIS Test Results Summary ASTM D6913 SIZE OF OPENING IN INCHES U.S.STANDARD SIEVE SIZE HYDROMETER 36" 12" 6" 3" 11/2" 3/4" 3/8" 4 10 20 40 60 140 200 100 90 = 80 W ?� 70 Im 60 W Z 50 Z W tU Ili 40 W a 30 20 10 0 1000.000 100.000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine Silt Clay BOULDERS COBBLES GRAVEL SAND FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture(%) Fines(%) Description Gravelly SAND, B-4 S-5 15 6.1 7.4 some silt PROJECT NO: 2760.01 PROJECT NAME: Zipper Geo Associates,LLC Geotechnical and Environmental Consultants DATE OF TESTING: 10/16/2023 Arlington Commercial Development AWEST Am Test Inc. L A e o R A T o R I E S Professional 13600 NE 126TH PL Analytical Suite C Services Kirkland, WA 98034 (425) 885-1664 Oct 25 2023 ZIPPER GEO ASSOCIATES, LLC 19019 36TH AVENUE W SUITE E LYNNWOOD, WA 98036 Attention: JAMES GEORGIS Dear JAMES GEORGIS: Enclosed please find the analytical data for your ARLINGTON COMMERCIAL DEVELOPMENT project. The following is a cross correlation of client and laboratory identifications for your convenience. CLIENT ID MATRIX AMTEST ID TEST B-1 S-2 5' Soil 23-AO18155 CONV B-2 S-3 7.5' Soil 23-AO18156 CONV B-4 S-4 10' Soil 23-AO18157 CONV Your samples were received on Monday, October 16, 2023. At the time of receipt, the samples were logged in and properly maintained prior to the subsequent analysis. The analytical procedures used at AmTest are well documented and are typically derived from the protocols of the EPA, USDA, FDA or the Army Corps of Engineers. Following the analytical data you will find the Quality Control (QC) results. Please note that the detection limits that are listed in the body of the report refer to the Practical Quantitation Limits (PQL's), as opposed to the Method Detection Limits (MDL's). If you should have any questions pertaining to the data package, please feel free to contact me. Sincerely, Aaron Young Vice President Project#: 2760.01 BACT = Bacteriological MET = Metals NUT=Nutrients MIN=Minerals CONV = Conventionals ORG = Organics DEM=Demand P.1 Am Test Inc. Professional 13600 NE 126TH PL Analytical Suite C Services Kirkland, WA 98034 1"EST (425) 885-1664 L A B O R A r o R i E s www.amtestlab.com ANALYSIS REPORT ZIPPER GEO ASSOCIATES, LLC Date Received: 10/16/23 19019 36TH AVENUE W Date Reported: 10/25/23 LYNNWOOD, WA 98036 Attention: JAMES GEORGIS Project Name: ARLINGTON COMMERCIAL DEVELOPMENT Project #: 2760.01 All results reported on an as received basis. AMTEST Identification Number 23-AO18155 Client Identification B-1 S-2 5' Sampling Date 10/16/23 Conventionals PARAMETER RESULT UNITS Q D.L. METHOD ANALYST DATE Cation Exchange Capacity 15.8 meq/100g 1 10.5 SW-846 9081 1 CM 10/19/23 AMTEST Identification Number 23-AO18156 Client Identification B-2 S-3 7.5' Sampling Date 10/16/23 Conventionals PARAMETER IRESULT UNITS Q D.L. METHOD JANALYST DATE (Cation Exchange Capacity 16.3 meq/100g 1 10.5 SW-846 9081 1CM 10/19/23 P.2 ZIPPER GEO ASSOCIATES, LLC Project Name: ARLINGTON COMMERCIAL DEVELOPMENT AmTest I D: 23-AO18157 AMTEST Identification Number 23-AO18157 Client Identification B-4 S-4 10' Sampling Date 10/16/23 Conventionals PARAMETER RESULT UNITS Q D.L. METHOD ANALYST DATE Cation Exchange Capacity 16.5 meq/100g 1 10.5 SW-846 9081 ICM 10/19/23 Aar n Young Vice President P.3 Am Test Inc. Professional 13600 NE 126th PL Analytical Suite C Services Kirkland, WA, 98034 EST (425) 885-1664 L A B O R A r o R I E s www.amtestlab.com QC Summary for sample numbers: 23-A018155 to 23-A018157 DUPLICATES SAMPLE# ANALYTE UNITS SAMPLE VALUE DUP VALUE RPD 23-A017935 Cation Exchange Capacity meq/100g 2.7 2.9 7.1 23-A018157 Cation Exchange Capacity meq/100g 6.5 5.1 24. STANDARD REFERENCE MATERIALS ANALYTE UNITS TRUE VALUE MEASURED VALUE RECOVERY Cation Exchange Capacity meq/100g 2.0 2.0 100. % Cation Exchange Capacity meq/100g 2.0 2.0 100. % BLANKS ANALYTE UNITS IRESULT Cation Exchange Capacity meq/100g < 0.1 Cation Exchange Capacity meq/100g < 0.1 PA LL `6LL LL O > > L CD ^W^ O LL 3 } 0 (D o N o zz zz > cr) O U) N Q a a w w o N a ..—N —N o U) 3 3 o uJ ON 0 0 ° a o a C o N G z O O a) O -o w O NOIlH0131SSH10 g g g o a IIOS W1SH U) U) U c m L S3N13% p a U o J QNHS% a J r � a W (o C a) U ,L I3AVHE)% L cn Q C) 3 U) Q O o Q O CQ E Q N FL o ` (6 Q Q z � N U w `�' N E '� L O d d � C O Q L w — m 0) U w _ C N Q co U) ._ w p a) 0) U `p p �_ Q J N 6 L L Lp W o Q C Q co g Q N .l1VAHHS 013103dS Q J n 0 � o m %)1N31N00 N s 01NHSb0 Q `m c m o s m N %)1N31N00 cN Mw- v 0 N N O o H1d30 W01108 E :N U 0 N 0 (seal) O ) O N U �I F Hld3a dOi Lo m om ro V t L N zb cN W N NOIlHNSIS3a U� U� U� ~ v V 2 NOIlH2iOIdX3 m m m a z U► x 0 z a o m QOK m ° R- 8N 8A0 s i Z p Z e 25 vU17 rcya �s uF i W Z q� u wJ o° °"t rc H? ~ cc oz< ���wo N p zz h 7 ba MMI 92rc za H Mn xW zzz K O CariN ro � K�Up<U Oym a xy C O ��w w � V '�Lwz fFF ZU 2 3N 3AV HlLB Im O t E'-' §§i5 j a d Gyg~]jy JOjl00 ONr�j m JZ O f0 �O�m00 �a ow E� g Uo > w u�1 ¢F UOp O � Z€�O� yZj ymyin omjw-o .m9 Q E o 6-dp Ou7_� U O LLJ o ° a W i io 000 U € 09 8 a xn ya �Q° rc w mo Q °T � o 5wW iw05�°�9 °zaooW w U�=� 3$ \ F o JFo8o�e °4 u°iiTJ�LLwSY�WF�F g��a �a � w GmU FWaoo2 �O] F�ZZ=jWFO yJy xF1V O FE op mo 11 n ZOa -5.j.. ?'oW F �S0 N Q `W N/ LL � vg Z= W Lu J W �- g Z3 0-0 Z. o 2i gLL > 10 ao o =z oy 2 iy Uo ay J � J Q ZL � 9m Z W• WLLLL oOo a th L_ W Q y > LU T 3 LO 'Wn WW z 8 w v K Z16 N Q o N Z i N 0 L y O O o O o O ipO r ¢ O a p Z W 0z (h y 3 ° y go `� p o ° ¢ i o 25 N cd m Sr i� U Z ° C x K N 4 g z r ° qg� w c� H r uS w k m z -Z a md` Z - �+ O c g �' o S Fa € a o� z � = � m = - W y :� o G ogyg w g Y wa LL. t �a a Z. 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I IIII ��s��<5mc n "o az II_ OS O 'Ti hO cn 1 ii I _Go w— —mowO I I z \ I ,�t, � \ •--t o \ I \ nn Zi - O J / d 1\I� r Q oe \ I I \ I i / \�\ z I 9 / / \\I ZN W \\I � 10 w III 1�111 � \_ _____�— —_�, \---- ____ ___. � d-�_ \----------- F d g CO U- O _ z w 6 0 111 1ZE esl 6 d.La5' Z —N ^' �a__.nzes W '- - a i < W f�2LL o J Zj cr Z /- - 0 z wdgo:£ —4ZOZ '90 JdV 6MP'OIZ[8VW\S9MOZ\3N 1S HMZ 0£MIlG8V8 13M\u0}6wlJV\uo}6wysOM\ WETRABBIT 7530 204th St NE Arlington, Washington 98223 Stormwater Operations & Maintenance Manual 1 6814 Greenwood Avenue N Seattle,WA 98103 T 206.522.9510 www.pacland.com Prepared By: Travis Cheshire, P.E. Reviewed By:Sean Mallon, P.E. Prepared:June 2024 PACLAND Project# 10700009 Maintain Stormwater Facilities The owner or operator of the project shall be responsible for maintaining the stormwater facilities in accordance with local requirements. Proper maintenance is important for adequate functioning of the stormwater facilities. The following maintenance program is recommended for this project: PACLAND Project#10700009 � ; IO 0n C W 10 > W o 0l c o \ W a C (U C th 6 N N Le d v v m a��c E o H N � y > U > OJ N L O T V M O E O/ C 0o E o N 00 C w N Ln N w O 4) N in .O u 01 O u a m a ar N N o a m m v u o 0o Y E Y c O a N o u w v 3 o O C C C QJ t) 2 G! L C Q O n) O G T v o E n E ~ a o E : ai W O 7 3 a N a c E E v u o = 3 � a m ;; m o p as u w E c = a A T w N y u N E ms ' v+ CO v 7 C Y _ _ Q> ; 7 x 0 ,u 0 - U 0 0 7- > 7E w 2u a= 440 M > « a, �n O C YO v W O 1 p > O v a L -0 w -c 0) M C C 'O O U C C L C Y M a m •3 c m y w a y '^ ° o om u E_ m in E T c °u O O) O �' L R N O) C E �0 •- 0/ L ° 0/ i ` G/ CO O) a GJ O o0 ;° 'v^ " C v u c cE1@ o ° o � r2v � Yv c t ° v ,� ° m c L a N •0. L L L V y r u a o u L L E v a L w ° c " n N o `v 3 a E c ° " >a m " E 3 i w L v o v v -o o . E m L c ° m E � � v OJ u O c O ] �+ 00 U v N 0J N !0 01 t O - 01 O C a L C .�-C C `o ? `° Y to a c .T a v ar u n a ai m oo c 8 a c a zu E -u c '00 ' •c ` C i 01 E L Gl u IL C a v A .� N L f0 y > 'c C C 'H C L O - T 0) O C C 0 3 E 75 C L 7 N 7 7 0 C H `1 C N u E O N V L.+ O O M vi ✓ O ar o '� 0/ a o c _ c v n 9 E •- m u u E a .y '`o `0 L M v u E m ar 'v,00 N O c E E a " m M v� M U L O N U O in Ol 07 'vi L L L T ~ V C U �• u � 3 d O N E L V C L 7 Oq oD .� w .� �' a, ,� - u o E �, E a' u v, u c u pC >. N L 0r y u _U v L O C I C N CL V 'j Y v� w O. C 01 0J ui m Y ~ > T o ° > o ? m L M M C c M r C 3 U u m a H C v1 H u .T F- n m am - f- .O > m M > .0 u C PACLAND Project#10700009 A \ \ \ \ CO _ Wm " " ; f k = b Q 3 j : \ k 0 0 { 0. \ ) 7 ) \ - - _ % - / - - - - } 2 $ � § { f/ $\ f \ � ) \ � � � � w cc fr cc E � � \ QJ ) } \ - - - ] § ƒ 2 ƒ 2 ƒ ■ ƒ Jf3 / 2 ƒ 2f2 ƒ 2 , Cu w ) \ 7 § _ w £ - _ C _ 2 _ ] _ CL _ - ILI \ . CL S w - \ � - } \� - - § \ \ � � C \\ au) f 2 � ( _ \ 2 § aIN 2 « r - - ( E � ) { � 2 7 § E � = - - ) 7 ) ) \ \ # \\ { )_ § \ � ) - _ \ § jam / { / > // ( / � � � 2a , � � O � \\ C \ \ ) \ < vIM « } Rtg £ / ff ± # 4) 2 } r • 4 < < 2 \ ( ƒ : § ■ _ " » a :E ƒi Cl � G ° - C ° \ f) © ~ E ) 7 j ! 3 \ \ _ U u u I / k > » kn PAcmND Project#m70o9 E /0 \ \ \ } \ � ) } � ) # $ R * _ _ _ _ $ � G2ƒ kk } ) - 0 _ - � \ wEa / ƒ ƒ ƒ 7 ƒ } ƒ { § f f2 ƒ k >.z z / k 2 LLJ 7 [ � - f - 0 ! \k / - / _ ! # ) _o /Af] { k ) ik e Cu E - UM ) Jm- OL J) \ \\ \ \\\ \2j \ Cu \ A� � k) 0 2 § � , ! > _ , - C - K . £ 2 _ ` E u2 z d Ot CO� « \ 0 o _ k 2 ) � 0 5 ; 00 ; < « < < « < < _ _ CrCLE _ - § 2 � � - f ® § \ / E 2 �i § § ) ! 2 2 000E © - t 2 \ ) fI § § t C $ � ' » : § 2 E Cu d a PAEUND Project#m70o9 C O C v —_ O`D 5 C Q. d � U Ol Y ` C C ° O a,'O ° N L O O� O C ?' N N O N N O O O � � N N O C m cu L pppp N O j 0 0 A O •' G C C w Ol N O O C V Y -a Cu me L C C {1 N N oo Q) N °. 0 o Ix, C � O Q O > N L H CDC m �••• Y w C O. UM Cu > O 41 y C 5 C °u �p O N O CO OO E N O ° CL N d v OJ — OC Q > L O C N 75� ° a ° a o co a ° o O v ° C Cr C f0 - v M. > v p > m 3 C n` w v >C v E .� a J43 ° o E C LL �n O C 3 `o Y (U £ O a E V C p °' E l! Y N Y O) N a 16 �I > U>. •m a) N > N N ✓ N O y 0 N N O. Y N O j Y .' O. c C O y �= oo w L. v 3 O y O I CL L 81 u •T � •a m N O ° -0N CO On C -D N C E N C E N c 4) v ° w E L •� 0 L E m v 0 O 7 y w O « C H f7 N O/ w Ip C M •L n � v a �o L y v v N E w E E N a Q Y N PACLAND Project# 10700009 r u v C 4) C L am. m C 3 v m C m 4C! 0 9 E � O A a m E E a a a d CL L } c Y N ? O C O OI CQ > > E m aCu E L C m Q V t0J ? 2 A 4J 41 C W t_ Q Q. ` � .0 •C V .ai V1 CO C m 9 O m W G V C Cu N :^ ? Z ? Z j Z y 2 > 2 2+ 'd x Y o v _ W C �. V y W n C M 3 a eu O 4U fO °% n u o y p w E C O O + c u C C C W a off+ L M N .2 m c C "O � " c ,vyi .A - u w 0o E a d no �° d D ? v C 4 m co G '� •N m E a d op m O °n L•' W O J�.d d 4/ y C N 6 yy CI a t m O` 3 W � In � N C N � N G 2• 6 2 4/ C 3 N Q p U vyi i4 C G N c o3 c m� N w v -2 G m v d ` N a d n v m o ILn c Y N m m `m ar 2 o U r m m m $ O OC c JT C T y c C c N H O C w O ie p u m a a 3 a A o Po• Q m a m d9q d cc E Li a 19 A c � N N a N c c c 10 4Ei ` > E 01 m o ` d E E o o o 0 as C 0 C < < y V n E m 0 � y Q m I>I ICI' J 11 E Q, E PACLAND Project#10700009 a Y C C u ? CO 0Ob 'COL _ N Y ~ d O O c � � tic 0 0 m w o v w L p U1 H aJ ap+ to C w 3 v O L m o E •3 m `o E a N gO N 0; CU i °/ c x nn y uo y w c w Y E v o Q c v E a Y > E E C N T ON ? y m Gl a @ O = m ar m O C O m O ` N N u y 0> E O C C u >'.- m E W .O N aJ O a ` O tw w >0 IV N YCLa E ° E Y a a C,0) °' o E m c = E w c o_ _ 'c ^ �[ O O E v _Q u m o m N p O. C N L Y a O ! Y O N O O aa1 m m ' E Q C C mEaZ a, / L £ Y m ° o •C G ate+ (a U ° a a as N E Y m u C G C C .ti m u m ar y o O d ? YO O. '-^ m -E 4 _ Y t L p aL.+ O v >O v O d s•de as dr o �+o. o o d C O _Cu0 O ' N O. o•v �o.O • s • as oP °:u• a > p m m w Q a O O o •v 4 •O e?8 U = Cu a O dCL od�o•e o �odrod IOU c n aJ Y m ?r e e o o Oo W Q E > > L a! LA. Oe• O.v •�o�neo• N a G. al m •O° o 'H v m C a 'uC7 6 N_ Y > N � m c c E G C a ax, — ` to E� s o a Y Y — c c }� 'O N Y = w O O v' T m V O Y N y� Oa O. 2N p GJ y `w - va a aQ W w 'O H CL 0 =a PACLAND Project#10700009 C 00 .N � N L �0 p p U C m C C C E Vm C C } m Y C J O Co L _ v � O d � vi c y d O B H y O a O C Q %0 a - m d ° ° y a J o > c a Oai a m o0 m m m w it U a a V u C m O u Y 6 C N a O u a oco z° a a i z r N N00 0N N N •- } Z } 7 y Z } Z y Z y Z y Z N X W C T 16 O 01 o w N Y u C Ol r c 'N Ol N C C .O j O N N '0 N fa N O p V C y u E a O Ol j a m Om0 O a 01 £ t J T cC 'O T ry m O u a d c 0 L C Cu m Cl . s v O) N m 00 Lgo O N m u 0o O c C - x L C C a N J f0 O 01 N OJ O .Q y U m 3 h m 2 _ U N X O C y y 9 N O a`d+ O po C '0 O 'm OJ Y O C m m m m O O C £ v 17 C o a a w 3 N 3 c o '3 0 o O w 'v C �`p .o y N o n0 a o v `o w y a `m c u p ar J y r c o o a a a m £ 0 0 C 3 f0 d OI N U1 m f0 0 O :.= w O E C Ol C N C '-I h Ol " E J C C h mc '� J C m a8. ''e a m �o C O u vC w w w w uCu C a U Q a Q Q Q Q Q d v 0o T Da m c e Cum QJ a c 3 N c Q C O O w C u 0` O 0 a '� to J O. C 4 m C L J OJ N C t0 pNp ti s Ca m o d d E O LOl C p N w u w Cc 2. s° w C *Q. zo3 oa 5 u Cr0 PACLAND Project# 10700009 ) \ ) \ \ \ \ / \ \ � \ / o \ S { 7z - Cu % � % \ } [ \ 0 75 o \� \ ] § ; a ` ! E t {i rr : t ) $ � k 2 k § @ 2E12 \ � � K fE / \ o f « } : & !� m epee a ) sw ) k7X § ! ) ) L = 0 = z \ { ( < OM ; - ® ix - I = ` ) \ ( | ) ! { ] E ; | § r [ § k ) § � � 4 ƒ » 1E ` !« � ■ � , f E ) \ E �� - 3 3 3 2 / ) / PAcmND Project# m7oo9 o y p -------- -__ __—__— W W _ J >� O W CL LY LU �e II Q Q V) r 1 g I 'Et E a �O� cI- E° na c v c a a > w c v o no � c C > c E v p m o m 01 c o 0 3 a m x c c O 3 a) v a c ' > c t > o o c N $ a N c `° o f m o ° o u c o >o o ° n x c v a :: 2 E o o_s v D c � c c o >°1 .n m W p o c ° u a p o 3 O ° Y v C '-" C = 0 C N in Cu O. y ? .� N C C •O tCo c) a m o m `u) m a ° m 3 o Q-, 3 v •� m o 3 Y a 0 > > c �c w Y_ m a! v co E -- s m c w v > u E w e m o 0 m m " 3 v = o c a` c v E m I v > CU 0 o c o E 3 °J c a m - Q o O E 3 `o ° c °' m e cam N w o p f6 .a aCi a c o m v c ° c ° m a A aci ? v a mt > a�i o o °c > v c > > v a u Q E o S c ° 0 u o .. c c p !_ s >>. c m a on w c v v m " v 3 v p- O C p_ > C N - m Oq u E m '� 'V d a m .a H m a m 0 0) m Ou C O C > C j Y ' `O p. h0 a>+ � p pQ C a p m c N 3 a p c E c v a `� ° v v `m' .. a : � , m r 'u m _^ c Y v = :� a, o a 0a —' ccccm ? cm � ama o ° .m � Yu, ^ E c a 7 n p v E v O 0 N 0 Y 0 m W - > Y i' m C .�+ la u 0 0 C a o E a 2 m p r +- ,� m c v oo c m o C v > c 3 3 io o a ,� .. ,� '� c m c v > Cu s o w oo N C - a C L Y Y N $ E -or O N N L 0 > 00 oc p a a L m jp > 3 c s c a +' a o > u c c O c Q)) S m p_ v ° o ° c .a v __ ° c c m n 0 m p. a—° p '� v y E N V C R C 7 C '� w C a m �.- N m C >'H t C C C O 3 Q m v C m y N 2 Y C C m 0 N ,a 'C 7 Op G) m m 0 C .O O O H Y m E 3 a E °1 = a s ai Cl) '� c m:E z .° > D m E a) m �o C o v E o 0 0 c 0 0 c c 01 . v v a v °o O c o )>a m y ° •` 0 3 u, a u m u o.- O D c 3 Y m s w m n s a S a u n PACLAND Project#10700009 w a 7 L m w d w Loo«.X.3 v d 3 u Q a c '� m c° a r V w w a o Cu o V ac o E .E - a cam c= u m w m E o o7uoa 4 E maw o,0 a o- E v o-'- w m mwLmo'u n 3 v� wy E v uu w Z Cl. o v. o a) "m o p 3 E - 3 w 3 m w a ` w g c m m p o w 'O c c 01 z p o C C 0.= C C m O w /o y c c d a c a 0 mw w mm>u Lw a u mu ` -0 E 'om o ° ow Ew w $ oauC m mo Q ' ow E cao-o Vw-ao E°vw0 a 0,0 w3 Cw « C c? 0 > - a ��uo a `�- > uc- -'v > wm ° y cc w o � 0000 omom w $ z � zEc-o3 as 0[ Cr cc 0 EL w r 3 N O y O O O d O O vi X > z > 2 > z y Z y z y Z W w ^ u "w 00 aL N d w O 7 O c w o w nm oY our c o � o Ya ` m ems c :Cr a- - u 0-0 c m c 3 - w w u m a-_ m c c w- m-•- r > c c c ^ w _ m E 3 E o rm c o o v «�� = oa our m w o W v v v w a w ° 3 a M o L .. a) . Om am we > mC c3a o u m w c o w a m'm w;n w� o o w u � W C u cw nY - wow � E >>Em ° cy a w. Nm Nwo¢a �L ono `- oa> E au a m c y 7 ° c a m 3 u > v = c H o E o m c m 3 c O w w OM C m L w > .x C 7 pp w O w w >+ °° ° ° w >w w o .O o ° c n` wn ° o cLaaa� co > v 'o o m Lc ar m omwma ovWQ) v Ea uE «+ m '^ n0 > "O m w .L. ¢ C 'm-a m > pM TO O m L vOi 7 N a 7 'D O O w m w.0 tw N L O N m C7 w •N C t C ° N 09 a h w C O c p u v � o ° � � a v ° r c 3 o.- > g� a v o '0 E y c w 3CL v�i of cw o CL cC o ° X m w L w w > o oE ¢e °Ec � o c a a m ci a w ama 3 Vw o W w U w p w G d C ¢ Q m N C � O c � � m �=' c •D m C �+ -0 m w t G! O C w C w O m p p 0 3 v o c c x •C V CeJ H c £ 0 a1 ',o 9 m cwE .� 00 X C = "O 1 d> C u OCC - PACLAND Project#10700009 � C O N 10 N C m MO N N p O C y U .n 'u A O V O N pJ _ O CL O H c v V O L ) d V E m C "O a fC0 O ate+ m u .0+ OV O T L _ 'Cio C_ 00 .n Q w N E CCL v O O '^ N fa ab E a Y O m a m O C v= O y Ou OO N aJ m cc N ° 2.-— J C m E w U m c a m 'c m ° v > E w N H N d C r C GJ > N 3 ° c ° v E Q u c o E Q n w a N v c o 0/ w d o Y > 3 A L ° E C 0 w uC � u ._ mV > N u > C V O a) C -0 O N � O C O E > 19 2 O O E Ja N E pd 0 N N ° 'O io = N E 'u t1 � sE� 7 s vJ a`J " ° vOi � = m s Cu « NN y 0 y 0 O y 0 y 0 y 0 N X } Z } Z } Z } Z } 2 } Z W N G u O 6J O v ° ° iy O Y C CJ V c ,«O- aL+ u0i — % � G GJ W V m OJ O - 7 w —'' to E N m w._ a c aJ U p E C ._ O N c u w C O C >,° O ai aJ L N O. y ` c '� 'e` c 0 N L M c > cvMC vc L 'y a` o o N a `O m c E 3 a v 3 0 - ° — C ry ° N 01 N 6 Y V o EU N N C C u aJ v w ro 3 aJ m «� aJ y m m E `u. > m a aJ E c ° m oLo ° o w o E a c 30=_ E c y c amvo ° � � E av .� ° c mm° E = 3 un a E c t .� vm o L > u 070 m w OEE � v'= = co a Yv ``° m ^ y .30 O O (5 N p 7 N 3 V w N C C E E u °1] Q N O N Lv°i O N O. c `! w O N L" E N > > C Q E �+ Y > y c. N > aL �m O v o `a c o o —'° o rN0 O .O w c s 3 CL c E'3 a° >o m n �a o c a m > c � T E io Q o a m N E E ° c C ° E ° ° c ° 3 `w o y c v y v R o f a c `o L m O w E o f0 C,•- E E Ol '� V 'O ,N .- p — a f9 Cu V1 N O uJ �' cu ° w C GJ C m°: N O.M- >O m f0 ° 0 w m c0 CJ N y (U E oco C y L N ? 0 E m ° E o'er `w w v v v a E u >� N 0 'N n= `0 y E N « v ° E O N y o E ° w v u o y v = � o w v ° a (D uF- 3a ° u E LLz °N a� V O V p w d ++ N p p ++ w w G C Q Q C m m Q m OC E Li O N b � O c a a D_ C C c C 0 d to 3 Ow O a � v H o Cu a m M E > •C C1 F = to w Jn a m PACLAND Project#10700009 = v E } 'u v E .6 v m c`oZ o`_ CL aE v m w ° c N ° u Oa m m.> O N N a N — O m c a) O N a 'a 6 A V Gl O O 0 'O w N C «O 73 t LLN -W N Cm p Cy DN COC ` E O E L -C N yC u ° 4! .0 N N L W'D m 'V L Y d m a C 0 ° >. -° o Q a v a Y ° m n c 0 0 N v a v > a � m omm 'v u o o acu l`pJ v ye da Fa-i m }' E 0 Z a m Cc N .0 Cc O O m ti m m N j 3 N y 0 O O y 0 m c d N .x y Z } Z } Z y Z �p € m U m W � 0 N t a c E v a o m la, u u u ° C ° Y Cuv -0 3 7 C GI m .6 E O C o E o 0 o p Q o ° 3 u °� " M c w E o 3 ° E c c c y oc o Cl « c c m c ° Y o v o u EL > xa y u c d E C N O Y 7 c p m " c m a N O v v c ° a � u v a, u m >, y �a c c m a E . m o c a 'E c m o c c m m v 3 E o $ ° °a o $ a y > m o o E c c� E > o o c `m o C NN � 'c Njmois C v 10 %mo � w O m a _ w O c C7 O m w Y m- w m u 3 :a N t-. 4! 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PAcmND Project# m7oo9 WET-RABBIT EXPRESS CAR WASH 7530 204th St NE Arlington, Washington 98223 Stormwater Site Plan M 9 IRVIV,"D 6814 Greenwood Avenue N Seattle,WA 98103 T 206.522.9510 www.pacland.com LE.1 C �CNAEL of w As`, el / rn 31 .VAL 2024.06.17 11:03:11-07'00' Prepared By: Travis Cheshire, P.E. Reviewed By:Sean Mallon, P.E. Prepared:December 2023 Revised:June 2024 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section Table of Contents Pale EXECUTIVESUMMARY...........................................................................................................................................3 SECTION 1—PROJECT OVERVIEW ..........................................................................................................................5 SECTION 2-EXISTING CONDITIONS SUMMARY.....................................................................................................8 SECTION 3—DEVELOPED CONDITIONS SUMMARY................................................................................................9 SECTION 4-OFF-SITE ANALYSIS...........................................................................................................................10 SECTION 5-CONDITIONS AND REQUIREMENTS...................................................................................................11 SECTION 6-FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN.........................................14 HYDROLOGICANALYSIS.................................................................................................................................................14 EXISTING SITE HYDROLOGY............................................................................................................................................14 DEVELOPED SITE HYDROLOGY........................................................................................................................................15 FLOWCONTROL SYSTEM...............................................................................................................................................16 WATERQUALITY SYSTEM..............................................................................................................................................16 SECTION 7-CONVEYANCE SYSTEM ANALYSIS AND DESIGN.................................................................................17 CONVEYANCE..............................................................................................................................................................17 100-YEAR FLOOD/OVERFLOW CONDITION.......................................................................................................................17 SECTION 8-SPECIAL REPORTS AND STUDIES.......................................................................................................18 SECTION 9-OTHER PERMITS...............................................................................................................................19 SECTION 10-CSWPPP ANALYSIS AND DESIGN.....................................................................................................20 SECTION 11-OPERATIONS AND MAINTENANCE MANUAL..................................................................................23 APPENDICES: A—BASIN MAPS AND CIVIL PLANS B—DESIGN CALCULATIONS C—GEOTECH REPORT D—STORMWATER OPERATIONS&MAINTENANCE E—CONSTRUCTION SWPPP PACLAND Project# 10700009 Page 2 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Executive Summaty The project site is located along the southeast quadrant of the intersection of 204t" Street NE and State Route 9 and is comprised of two Snohomish County tax parcels.Tax Parcel 310514-001-006-00 is a developed site with a property address of 7530 204th Street NE in Arlington, Washington. This parcel encompasses 0.76 acres of relatively level land with an unoccupied commercial building formerly occupied by Arlington Family Medicine located in the southeastern portion of the parcel.The building is a 3,520 square foot, one-story,wood-framed structure reportedly built in 1984.Asphalt surfaced drive lanes and parking are found to the north,west, and south of the commercial building.The development is serviced by underground utilities and includes an underground stormwater conveyance system. Vegetation includes ornamental plantings in parking lot islands and around the building, a row of large trees along the west and south property lines which appear to serve as a wind block, and a lawn south of the building. Asphalt pavements near the west and south rows of trees exhibit moderate root damage. Tax Parcel 310514-001-010-00 is a relatively level, undeveloped site located east of and adjoining the southern portion of the above discussed developed parcel's east property line.The parcel is irregular in shape and encompasses 0.76 acres. It appears that some underground utilities may be located near the east property line. Vegetation within the undeveloped parcel primarily consists of well-developed tall grasses with dense blackberry brush along its west and north property lines. The project consists of demolishing the existing medical office building, and all existing surface and underground (utilities) site improvements. A+/-4,920 sf Wet Rabbit Express Car Wash (conveyor type) and a +/-450 sf canopy structure for attended, point-of-sale transactions will be constructed along with surface parking for employees,vacuum stalls, landscaping, access drive between 2041"St NE and 771n Ave NE, and supporting utility infrastructure. The project will manage stormwater runoff for both flow control and water quality per 2019 DOE requirements. The roof drainage will be collected and conveyed to the underground stormwater infiltration facility(gravel filled trench) located west of the building beneath the drive aisle.The balance of the site including a portion of the access drive on the neighboring parcel will manage stormwater runoff via multiple catch basin inlets strategically placed at low points.The runoff will then be conveyed underground via a network of storm piping. Prior to entering the infiltration facility oil control will be provided via a CPS separator immediately upstream of the infiltration trench. Stormwater runoff for the neighboring parcel will be managed via a shallow surface infiltration pond.The access road and parking area will collect and convey runoff via sheet flow to the gutter line and discharge to a riprap spillway into the surface pond.The stormwater infiltration systems will infiltrate 100%of all stormwater runoff generated by the project.The native soils below the infiltration facility will complete the water quality treatment process as they meet DOE requirements with respect to organic content and cation exchange capacity(CEC).A piped overflow from the infiltration facility to the municipal system will be provided as an added precaution for large storm events. Design Criteria: The City of Arlington has adopted the 2019 Washington State Department of Ecology Stormwater Management Manual for Western Washington (SMMWW).The site development will result in more than 5,000 sf of new hard surfaces therefore must comply with Minimum Requirements 1-9. Applicable stormwater requirements are outlined in Table 1 below. PACLAND Project#10700009 Page 3 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Table 1 (2019 DOE SMMWW) Jurisdictional Requirements Peak Runoff Control: Match the pre-developed discharge rates from 50%of the 2-year peak flow up through the full 50-year peak flow. Projects discharging directly to approved water bodies may omit this requirement. Water Quality: Upstream of detention: 91%of runoff volume Downstream of detention: Full 2-year release rate Conveyance Design: 25-year event Hydrologic Design Western Washington Hydrology Model (WWHM2012, updated Method: 1/27/23) for water quality and water quantity analysis Proposed Drainage System: The project will manage stormwater runoff for both flow control and water quality per 2019 DOE requirements. The roof drainage will be collected and conveyed to the underground stormwater infiltration facility(gravel filled trench) located west of the building beneath the drive aisle.The balance of the site including a portion of the access drive on the neighboring parcel will manage stormwater runoff via multiple catch basin inlets strategically placed at low points.The runoff will then be conveyed underground via a network of storm piping. Prior to entering the infiltration facility oil control will be provided via a CPS separator immediately upstream of the infiltration trench. Stormwater runoff for the neighboring parcel will be managed via a shallow surface infiltration pond.The access road and parking area will collect and convey runoff via sheet flow to the gutter line and collected at an into and then conveyed to the surface pond via underground storm pipe.The stormwater infiltration systems will infiltrate 100%of all stormwater runoff generated by the project.The native soils below the infiltration facility will complete the water quality treatment process as they meet DOE requirements with respect to organic content and cation exchange capacity(CEC). Construction of the new storm drainage facilities will be in accordance with the Washington State Department of Ecology's 2019 SMMWW as required by the City of Arlington. PACLAND Project#10700009 Page 4 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington SectionProject �'rrh�,,,NE E+,m,n v —7LNgnallor-9—r.a L.,. 1 30�I�IN ��� n 71'IsIANE� la:�.91NE 1 1 `2 O � A � 'elE1 Pl VE - - VICINITY MAP NOT TO SCALE Figure 1.0-Site Location PACLAND Project#10700009 Page 5 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington x aRr Ilk ..� � � r a r Figure 1.1—Aerial Image(from Google Maps) Location: 7530 204t" Street NE, Arlington, Washington, 98223 Section/Township/Range: A portion of the NW%of Section 14,Township 31 North, Range 5 East, W.M. Parcel/Tax Lot: 310514-001-006-00 (0.76 AC) and 310514-001-010-00 (0.76 AC) Disturbed Area: +/- 1.33 AC City, County,State: Arlington, Snohomish County, Washington Governing Agency: City of Arlington Design Criteria: 2019Washington State Department of Ecology Stormwater Management Manual for Western Washington (SMMWW). PACLAND Project#10700009 Page 6 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Soils: Geotechnical Report Per the Geotechnical Engineering Report prepared by ZipperGeo, dated March 28, 2024;The subsurface evaluation completed by ZGA for this project included four borings (B-1 through B-4) and one cone penetrometer test (CPT-01). CPT-01 was completed near the center of the proposed car wash development (currently developed western parcel) and extended to a depth of about 60 feet below grade.The CPT exploration included seismic shear wave velocity measurements. Borings B-1 and B-2 were completed in the north and south portions of the western parcel's existing parking lot, respectively, and extended about 36%feet below grade. Borings B-3 and B-4 were completed in the undeveloped eastern parcel and extended about 31%to 36%feet below grade. Groundwater monitoring wells were installed in borings B-1 through B-3 to evaluate changes in groundwater levels through the wet season. At the time drilling groundwater was observed in borings B-1 through B-3 about 25 to 30 below existing ground surface. Soil conditions observed in the site explorations are consistent with normally consolidated glacial recessional outwash deposits of the Marysville Sand Member and generally consist of the following. • Loose to medium dense sand with variable silt and silt with variable sand content in the upper 5 to 7%2 feet. Soil mottling was observed in some of the samples collected in this depth range. • From about 5 to 7%2 feet down to about 15 to 17%2 feet,the outwash generally consists of medium dense to very dense gravelly sand to sandy gravel with trace to some silt. • From about 15 to 17%2 feet to the maximum depth explored at 60 feet below grade,the outwash generally consists of loose to medium dense sand with trace to some silt. Based on the results of the subsurface exploration and analysis, stormwater infiltration systems appear geotechnically feasible.A summary of grain size analysis tests relative to stormwater infiltration is provided below. Summary of Grain Size Analysis Tests Relative to Stormwater Infiltration Sample Initial(unfactored) Sample Design Infiltration Exploration Depth Soil Formation Saturated Hydraulic Number Rate'(in/hr) (ft) Conductivity(in/hr( B: S-3 7% Marysville Sand Member 20,2 3.6 B-1 S4 10 Marysville Sand Member 37.1 6.7 B-1 5-5 10 Marysville Sand Member 19.3 3.5 B-2 S-2 5 Marysville Sand Member 3.8 0.7 B-2 5-3 7% Marysville Sand Member 126 2.3 B-2 S-4 10 Marysville Sand Member 15.6 2.8 B-2 5-5 15 Marysville Sand Member 14.7 2.6 B-3 S-2 5 Marysville Sand Member 39.9 7.2 B-3 S-3 7% Marysville Sand Member 2.0 0.4 B-3 S-4 10 Marysville Sand Member 4.4 0.8 B-3 S-5 15 Marysville Sand Member 4.5 0.8 B-4 S-2 5 Marysville Sand Member 11.9 2.2 B-4 S-3 7% Marysville Sand Member 8.3 1.5 B-4 S-5 15 Marysville Sand Member 28.4 5.1 FlInclude, rrec Correction Factors:CFv=0.5,CFt=0.4,and Um=0.9 For additional details this report is included in Appendix C. PACLAND Project#10700009 Page 7 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section • Conditions Summary The project site is located along the southeast quadrant of the intersection of 204t" Street NE and State Route 9 and is comprised of two Snohomish County tax parcels.Tax Parcel 310514-001-006-00 is a developed site with a property address of 7530 204th Street NE in Arlington, Washington. This parcel encompasses 0.76 acres of relatively level land with an unoccupied commercial building formerly occupied by Arlington Family Medicine located in the southeastern portion of the parcel.The building is a 3,520 square foot, one-story,wood-framed structure reportedly build in 1984.Asphalt surfaced drive lanes and parking are found to the north,west, and south of the commercial building.The development is serviced by underground utilities and includes an underground stormwater conveyance system.The existing stormwater management system does not appear to be connected to the municipal system, so it is assumed that the stormwater infiltrates into the underlying soils. Vegetation includes ornamental plantings in parking lot islands and around the building, a row of large trees along the west and south property lines which appear to serve as a wind block, and a lawn south of the building. Asphalt pavements near the west and south rows of trees exhibit moderate root damage. Tax Parcel 310514-001-010-00 is a relatively level, undeveloped site located east of and adjoining the southern portion of the above discussed developed parcel's east property line.The parcel is irregular in shape and encompasses 0.76 acres. It appears that some underground utilities may be located near the east property line. Vegetation within the undeveloped parcel primarily consists of well-developed tall grasses with dense blackberry brush along its west and north property lines. Stormwater runoff appears to sheet flow from SE to NE where it either infiltrates directly into the underlying soils or to the drainage ditch along the northern property boundary. PACLAND Project#10700009 Page 8 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington SectionDeveloped • • • Summary The project will manage stormwater runoff for both flow control and water quality per 2019 DOE requirements. The roof drainage will be collected and conveyed to the underground stormwater infiltration facility(gravel filled trench) located west of the building beneath the drive aisle.The balance of the site including a portion of the access drive on the neighboring parcel will manage stormwater runoff via multiple catch basin inlets strategically placed at low points.The runoff will then be conveyed underground via a network of storm piping. Prior to entering the infiltration facility oil control will be provided via a CPS separator immediately upstream of the infiltration trench. Stormwater runoff for the neighboring parcel will be managed via a shallow surface infiltration pond.The access road and parking area will collect and convey runoff via sheet flow to the gutter line and collected at an into and then conveyed to the surface pond via underground storm pipe.The stormwater infiltration systems will infiltrate 100%of all stormwater runoff generated by the project.The native soils below the infiltration facility will complete the water quality treatment process as they meet DOE requirements with respect to organic content and cation exchange capacity(CEC). Construction of the new storm drainage facilities will be in accordance with the Washington State Department of Ecology's 2019 SMMWW as required by the City of Arlington. PACLAND Project#10700009 Page 9 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section • Analysis Upstream Analysis Due to the topography of the area,the site does not experience a significant amount of off-site run-on. The public right-of-way to the west and north of the car wash parcel are down gradient. The area west of the car wash parcel is comprised of an existing drainage ditch down gradient from parking area. South of car wash site is an existing parking area which is situated approximately 5' higher than the parking area however it is contained within curbing.The area between the two parking areas is approximately 10—12 feet with no significant stormwater run-on generated due to the tree canopy above. and surrounding properties along the north, south, and west sides of the site are downgradient from the project and minimal stormwater run-on is anticipated. Downstream Analysis This design proposes to route all runoff from target impervious surfaces generated from the project to an underground infiltration facility.The infiltration facility has been designed to infiltrate 100%of all surface water runoff. Therefore, the proposed development is not anticipated to have a significant impact to the existing downstream stormwater conveyance system. PACLAND Project#10700009 Page 10 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington •n 5 - Conditions • • Requirements As required by the 2019 Stormwater Management Manual for Western Washington (SWMMWW) this project is subject to full drainage review.Therefore, the storm drainage design for this project is required to comply with all nine (9) Minimum Requirements.The requirements have been met as follows: Minimum Requirement#1: Preparation of Stormwater Site Plans This project proposes to replace greater than 2,000 square feet of impervious surface;thus, Minimum requirement#1 applies and a Stormwater Site Plan must be prepared for review by the local jurisdiction. Response: This Storm Drainage Report has been prepared to address this requirement. Minimum Requirement#2: Construction Stormwater Pollution Prevention All erosion and sediment control measures shall be governed by the requirements of Department of Ecology's 2019 Stormwater Management Manual for Western Washington and the General Permit for Construction Stormwater.The thirteen elements as identified in the manual and provided below will be incorporated into the TESC plans: Element 1: Preserve Vegetation/Mark Clearing Limits Element 2: Establish Construction Access Element 3: Control Flow Rates Element 4: Install Sediment Controls Element 5: Stabilize Soils Element 6: Protect Slopes Element 7: Protect Drain Inlets Element 8: Stabilize Channels and Outlets Element 9: Control Pollutants Element 10: Control De-watering Element 11: Maintain BMPs Element 12: Manage the Project Element 13: Protect Low Impact Development BMPs Response:Erosion and sediment control measures will be implemented during construction to address the above elements as needed. See Section 10 of this report for a complete description of the construction and erosion control strategies being implemented.A Construction SWPPP will be provided prior to construction permit issuance. Minimum Requirement#3: Source Control of Pollution All known, available and reasonable source control BMPs must be applied to all projects. Source control BMPs must be selected, designed, and maintained according to the 2019 SMMWW. Response: Source control will be provided as needed per Volume IV of the SMMWW. PACLAND Project#10700009 Page 11 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Minimum Requirement#4: Preservation of Natural Drainage Systems and Outfalls Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location,to the maximum extent practicable.The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters and downgradient properties. All outfalls require energy dissipation. Response: The developed site will discharge to the some locations as in the current condition. Stormwater runoff within the car wash parcel and a small portion of the neighboring parcel will be routed underground to a subsurface infiltration facility(gravel filled infiltration trench). The neighboring parcel will discharge stormwater runoff to a shallow surface infiltration pond. The proposed site improvements will not alter the existing drainage patterns, thus preserving the natural drainage system/outfall. Construction of the new storm drainage facilities will be in accordance with the Washington State Department of Ecology's 2019 SMMWW, as required by the City of Arlington. Minimum Requirement#5: On-site Stormwater Management Projects shall employ On-site Stormwater Management BMPs in accordance with the following projects thresholds, standards, and lists to infiltrate, disperse, and retain stormwater runoff on-site to the extent feasible without causing flooding or erosion impacts. Response: This project has chosen to meet the Low Impact Development Performance Standard by infiltrating 100%of the stormwater runoff generated by the development.Additionally, amended soils shall be utilized for all disturbed landscape areas per BMP T5.13:Post-Construction Soil Quality and Depth. Minimum Requirement#6: Runoff Treatment Projects in which the total of effective, pollution-generating hard surface (PGHS) is 5,000 SF or more in a threshold discharge area of the project require construction of stormwater treatment facilities. Projects in which the total of pollution-generating pervious surfaces (PGPS) is three-quarters (3/4) of an acre or more in a threshold discharge area, and from which there is a surface discharge in a natural or man- made conveyance system from the site also require treatment facilities. Response: Target Pollutant-generating impervious surfaces(PGIS)associated with the project are comprised primarily of the private roadway, drive aisles and parking areas throughout the site. Runoff from sidewalks that drain to these areas are also included in the PGIS total area. PGIS surfaces from the car wash parcel will be treated for oil control via a CPS O/W separator prior to entering the underground infiltration facility. The native soils below the infiltration facilities(gravel trench and surface pond) will complete the water quality treatment process as they meet DOE requirements with respect to organic content and cation exchange capacity(CEC). See Section 6 of this report for water quality treatment design. Minimum Requirement#7: Flow Control Projects must provide flow control to reduce the impacts of stormwater runoff from hard surfaces and land cover conversions.The requirement below applies to projects that discharge stormwater directly, or indirectly through a conveyance system, into a fresh waterbody. Stormwater discharges shall match developed discharge durations for the range of pre-developed discharge rates from 50%of the pre- developed 2-year peak flow up to the full 50-year peak flow. The pre-developed condition should match a forested land cover. Proper Flow Control BMPs shall be selected and designed according to the current SMMWW. PACLAND Project#10700009 Page 12 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Response:Per SMMWW requirements, existing conditions will be treated as fully forested. Flow control will be achieved through 100%infiltration of the stormwater runoff generated from the project. See Section 6 of this report for flow control design. Minimum Requirement#8:Wetlands Protection The thresholds identified in Minimum Requirement#6 and Minimum Requirement#7 shall also be applied for any discharge to wetlands. Response: This Minimum Requirement is not applicable, as the project does not discharge to a wetland. Minimum Requirement#9: Operation and Maintenance An operation and maintenance manual that is consistent with the provisions in the SMMWW shall be provided for proposed runoff treatment and Flow Control BMPs, and the parties responsible for maintenance and operation shall be identified. Response: A Stormwater Facility Operation and Maintenance Manual is included in Appendix D. PACLAND Project#10700009 Page 13 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section 6 - Flow Control and Water Quality Facility Analysis The City of Arlington standards reference the 2019 SMMWW and require that the developed discharge durations match the pre-developed durations for 50%of the pre-developed 2-year peak flow up to the full 50-year peak flow.The pre-developed condition shall be considered as a forested land cover. Hydrologic Analysis Hydrologic analysis for evaluating the flow frequency comparison between the existing conditions and proposed conditions for the project was performed using the Washington Department of Ecology's Wester Washington Hydrologic Method of computer modeling WWHM2012 program.The model utilizes design data for specific soil types and vegetative covers to simulate runoff. The software program routes the flows generated from the basin analysis through a proposed conveyance system to storm water BMPs or structural detention facilities.The model is designed to meet the standard requirements stated in the Department of Ecology's Stormwater Management Manual for Western Washington. A single model was created to analyze the existing conditions in comparison with the proposed conditions to determine the anticipated increase in peak flows for the project. Refer to Appendix B,for model results. Existing Site Hydrology Tax Parcel 310514-001-006-00 (Parcel 1) encompasses 0.76 acres of relatively level land with an unoccupied commercial building formerly occupied by Arlington Family Medicine located in the southeastern portion of the parcel.The building is a 3,520 square foot, one-story, wood-framed structure reportedly build in 1984. Asphalt surfaced drive lanes and parking are found to the north, west, and south of the commercial building.The development is serviced by underground utilities and includes an underground stormwater conveyance system.The existing stormwater management system does not appear to be connected to the municipal system, so it is assumed that the stormwater infiltrates into the underlying soils. Vegetation includes ornamental plantings in parking lot islands and around the building, a row of large trees along the west and south property lines which appear to serve as a wind block, and a lawn south of the building. Tax Parcel 310514-001-010-00 (Parcel 2) is a relatively level, undeveloped site located east of and adjoining the southern portion of the above discussed developed parcel's east property line.The parcel is irregular in shape and encompasses 0.76 acres. Vegetation within the undeveloped parcel primarily consists of well-developed tall grasses with dense blackberry brush along its west and north property lines. Stormwater runoff appears to sheet flow from SE to NE where it either infiltrates directly into the underlying soils or to the drainage ditch along the northern property boundary. The pre-developed conditions for the project site are shown in Table 2A&2B below. Existing peak runoff rates were determined using the WWHM2012 modeling software and the calculations can be found in Appendix B. Table 2A—Car Wash Site(Parcel 1) Pre-Developed(Existing)Conditions Land Cover Area (AC) Roof 0.08 Landscape 0.22 PACLAND Project#10700009 Page 14 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Sidewalk 0.04 Pavement/Gravel 0.42 Total 0.76 *Per the requirements of the SMMWW,all existing conditions shall be modeled as forested conditions. Table 2B—Future Development Site (Parcel 2) Pre-Developed(Existing)Conditions Land Cover Area (AC) Undeveloped—Grass& 0.76 Shrubs Total 0.76 *Per the requirements of the SMMWW,all existing conditions shall be modeled as forested conditions. Developed Site Hydrology The project will manage stormwater runoff for both flow control and water quality per 2019 DOE requirements. The roof drainage will be collected and conveyed to the underground stormwater infiltration facility (gravel filled trench) located west of the building beneath the drive aisle. The balance of the site including a portion of the access drive on the neighboring parcel will manage stormwater runoff via multiple catch basin inlets strategically placed at low points. The runoff will then be conveyed underground via a network of storm piping. Prior to entering the infiltration facility oil control will be provided via a CPS separator immediately upstream of the infiltration trench. Stormwater runoff for the neighboring parcel will be managed via a shallow surface infiltration pond. The access road and parking area will collect and convey runoff via sheet flow to the gutter line and collected at an into and then conveyed to the surface pond via underground storm pipe.The stormwater infiltration systems will infiltrate 100%of all stormwater runoff generated by the project.The native soils below the infiltration facility will complete the water quality treatment process as they meet DOE requirements with respect to organic content and cation exchange capacity(CEC). Construction of the new storm drainage facilities will be in accordance with the Washington State Department of Ecology's 2019 SMMWW, as required by the City of Arlington. Refer to Appendix B for detailed WWHM analysis results.The developed conditions for the project site are shown in Tables 3A&3B below. Table 3A-Car Wash Site (Sub basin A) Developed(Proposed)Conditions Land Cover Area (AC) Roof/Canopy 0.137 Landscape 0.240 Sidewalk 0.026 Pavement 0.433 Total 0.836 Table 3B- Future Development Site(Sub basin B) Developed(Proposed)Conditions Land Cover Area (AC) Roof/Canopy 0.000 Landscape 0.472 PACLAND Project# 10700009 Page 15 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Sidewalk 0.000 Pavement 0.209 Total 0.681 The area within the public right-of-way has been excluded from developed conditions as the stormwater runoff from this area is currently managed by the municipal stormwater system. Flow Control System The project will manage stormwater runoff for flow control per 2019 DOE requirements by implementing a below grade infiltration system.The infiltration gallery is 15'W x 1001 x 4'D at the base with side slopes of 1.5H:1V and comprised of gravel trench with a network of perforated pipes configured as a manifold.The system has been designed to infiltrate 100%of the stormwater runoff generated by the by the car wash parcel (sub basin A).The surface infiltration pond on the adjacent parcel (sub basin B) has been designed to infiltrate 100%of the stormwater runoff generated by the access road and parking area. Refer to Appendix B,for WWHM model results. Water Quality System Per the 2019 SWMMWW,the water quality facilities shall be sized to treat the 915t percentile of the 24- hour runoff model upstream of detention and the full 2-year release rate downstream of detention. Upstream of the infiltration facility oil control will be provided via a CPS O/W separator.The native soils below the infiltration facility will complete the water quality treatment process as they meet DOE requirements with respect to SSC-6 Soil physical and Chemical Suitability for Treatment. PACLAND Project#10700009 Page 16 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section • • • • • I • Conveyance On-site storm water conveyance shall be calculated through gravity flow analysis of the piping network. Based on a 100-year storm event, peak runoff shall be routed through the system and determined to be adequate. A Uniform Flow Analysis utilizing Manning's equation was employed with a Manning's "n" value of 0.012. Manning's equation - _ 1.49 x A x R Z Q /3 x S 1/2 n With: Q= Flow from 100-year storm event (1.36 CFS) n = Manning's Roughness Coefficient(0.012) A= Flow Area (SF) R= Hydraulic Radius =Area/Wetted Perimeter (LF) S=Slope of the pipe (ft/ft) Conveyance calculations are included in Appendix B. 100-Year Flood/Overflow Condition Review of the current FEMA FIRM maps (map#53061C0392F) indicates that the project site lies within the Zone designation X, meaning the subject property is within an area determined to be outside the 500-year floodplain. The stormwater system for this project has been designed to address storm events in accordance with design criteria described previously. In the event of a larger storm, it is unlikely that the system would fail. During extreme storm events the stormwater runoff could potentially pond within a few isolated areas of the access drive within the car wash parcel until exiting at the driveway entrance along 2041" St. This condition is highly unlikely and could potentially occur for storms in excess of the 500-year design storm event. PACLAND Project#10700009 Page 17 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section i Special Reports and The following Special Reports and Studies were used or have been completed for this project: • Arborist Report, prepared by Greenforest Incorporated, dated October 12, 2023. • Geotechnical Engineering Investigation Report, prepared by ZipperGeo, dated March 28, 2024. • Phase I Environmental Site Assessment, prepared by ZipperGeo, dated October 24, 2023. • Wetland Letter of Findings, prepared by Harmsen, dated October 24, 2023. • Traffic Impact Analysis, prepared by Transpogroup, dated December 2023. PACLAND Project# 10700009 Page 18 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington SectionOther Permits ' The following governmental approvals or permits will likely be required for this project: • Zoning Permit • Design Review • SEPA • Construction Permit (Civil) • Building Permit • Construction Stormwater General Permit/NPDES Permit—Department of Ecology These permits will require approval by the City of Arlington and Department of Ecology. PACLAND Project#10700009 Page 19 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section 10 - CSWPPP Analysis and Design All erosion and sediment control measures shall be governed by the requirements Department of Ecology's 2019 Storm Water Management for Western Washington. A Stormwater Pollution Prevention Plan (SWPPP)will be prepared for this project. A temporary erosion and sedimentation control plan will be prepared to assist the contractor in complying with these requirements. The Erosion and Sediment Control (ESC) plan will be included with the construction plans. 1. Construction Sequence and Procedure The proposed development will include an erosion/sedimentation control plan designed to prevent sediment-laden run-off from leaving the site during construction. The erosion potential of the site is influenced by four major factors: soil characteristics,vegetative cover,topography, and climate. Erosion/sedimentation control is achieved by a combination of structural measures, cover measures, and construction practices that are tailored to fit the specific site. The contractor will be responsible for implementing the following erosion control and storm water management control measures. The contractor may designate these tasks to certain subcontractors as they see fit, but the ultimate responsibility for implementing these controls and ensuring their proper functioning remains with the contractor. The order of activities will be as follows. Phase 1 1. Prior to any construction work on the site, representatives from the City of Arlington must approve the storm water pollution prevention plan. 2. Mark clearing limits. 3. Install inlet protection to all existing catch basins. 4. Install temporary stabilized construction entrance. Existing paved area to remain and be utilized until construction phasing requires removal. 5. Install perimeter silt fences, interceptor swales, etc. 6. Install sediment control pond and/or tank(s). 7. Remove any existing structures that may be on site. 8. Protect and stabilize slopes. 9. Begin clearing and grubbing operations. Clearing and grubbing done from October Vt through April 30t" is authorized as long as there are erosion and sediment control measures. 10. Commence site grading. Phase 2 1. Disturbed areas of the site where construction activity has ceased for more than 7 days between May 1 and September 30 or 2 days between October 1 and April 30 shall be temporarily seeded and watered. 2. Construct building pad and install concrete wash out area. 3. Construct permanent storm water facilities. Remove temporary sedimentation ponds. 4. Install utilities, underdrains, storm sewers, curbs and gutters. 5. Install inlet/outlet protection at the locations of all grate inlets, curb inlets, and at the ends of all exposed storm sewer pipes. 6. Prepare site for paving. Finalize pavement subgrade preparation. PACLAND Project#10700009 Page 20 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 7. Remove inlet protection around inlets and manholes no more than 48 hours prior to placing stabilized base course. 8. Install base material as required for pavement. Pave site. Do not pave over catch basins. 9. Complete final grading in non-parking areas and install permanent seeding and planting. 10. Remove silt fencing only after all paving is complete and exposed surfaces are stabilized. 11. Remove temporary construction exits only prior to pavement construction in these areas (These areas are to be paved last). The degree of erosion risk on the proposed project site is high given the proximity to a steep slope. The contractor shall refer to the geotechnical report for further recommendations. 2. Temporary Soil Stabilization Temporary stabilization practices for this project include: • Temporary seeding and planting of all unpaved areas using the hydro-mulching grass seeding technique. • Mulching exposed areas. • Installation of rolled erosion control products. Structural practices for this project include the following. Refer to the Erosion Control plans for specific locations and details: • Inlet protection using fiber fabric. • Perimeter protection using silt fences. • Stabilized construction entrance/exit points and staging area. • Temporary sediment tank. • Silt fence. Daily inspection of the erosion control measures will be required during construction. Any sediment buildup shall be removed and disposed offsite at an appropriate disposal facility. Vehicle tracking of mud off-site shall be avoided. A gravel construction entrance/exit will be installed at a location to enter the site. The construction entrance/exit is a minimum requirement and may be supplemented if tracking of mud onto public streets becomes excessive. In the event that mud is tracked off site, it shall be swept and disposed of offsite on a daily basis. Because vegetative cover is the most important form of erosion control, construction practices must adhere to stringent cover requirements. More specifically,the contractor will not be allowed to leave soils open for more than 7 days between May 1st and September 30th and 2 days between October 1st and April 301". Soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. Applicable practices include, but are not limited to,temporary and permanent seeding, sodding, mulching, plastic covering, and soil application of polyacrylamide. Soil stockpiles must be stabilized from erosion, protected with sediment trapping measures, and,where possible, be located away from storm drain inlets, waterways and drainage channels. PACLAND Project#10700009 Page 21 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington 3. Temporary Sediment Control Construction storm water shall be detained on-site during construction in a temporary sediment control tank located at the northeast corner of the project.The DOE requires temporary sediment storage to be designed to manage the 2-year developed peak flow. 4. Permanent Erosion Control and Site Restoration Upon completion of the project, areas of the site that are not stabilized with paving, rooftops, or landscaping as shown on the site plans will be protected with either grass, ground cover/plantings or existing vegetation as shown on the Landscape Plans. S. Inspection Sequence The construction site operator will periodically inspect its sites. Because our project disturbs more than one acre, a certified erosion and sediment control lead will be identified within the SWPPP. This individual will be present on site or on call at all times. 6.Control of Pollutants Other than Sediments Pollutants shall be controlled on the work site through the utilization of a centralized area for equipment, a concrete truck washout, and an area designated for temporary storage of debris and stockpiled materials. PACLAND Project#10700009 Page 22 Wet Rabbit Express Car Wash Stormwater Site Plan Arlington,Washington Section I I - Operations and Maintenance A manual detailing the operations and maintenance for all privately maintained conveyance and collection facilities is included in Appendix D. 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