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RS_DRAINAGE_TECHNICAL_INFORMATION_REPORT (TIR)_20250829_V1.pdf
Page | 1 Ó Site Design, LLC Saleh Foundation Center TECHNICAL INFORMATION REPORT (TIR) for SALEH FOUNDATION CENTER 4108 and 41XX Jones Ave NE Renton, WA 98056 Site Design Project number: 25014 Project File Number: PR24-000328 Prepared for Muhammad Faisal 4024 Jones Ave NE Renton, WA 98056 (206) 778-8323 Prepared by Site Design, LLC. 8825 34th Ave NE, Suite L486 Tulalip, WA 98271 (206) 914-1966 Report Issue Date: August 20, 2025 Page | 2 © Site Design, LLC Saleh Foundation Center TECHNICAL INFORMATION REPORT SALEH FOUNDATION CENTER TABLE OF CONTENTS Project Overview ......................................................................................................... 4 Predeveloped Site Conditions ..................................................................................... 4 Developed Site Conditions .......................................................................................... 5 Natural Drainage System Functions ............................................................................ 9 SECTION I CONDITIONS AND REQUIREMENTS SUMMARY ................................... 22 Core Requirements.................................................................................................... 22 SECTION II OFF-SITE ANALYSIS ............................................................................... 25 SECTION III FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN ................................................................................................................ 43 Existing Site Hydrology (Part A) ................................................................................ 43 WWHM Input .......................................................................................................... 43 Developed Site Hydrology (Part B) ............................................................................ 46 Performance Standards (Part C) ............................................................................... 51 Flow Control System (Part D) .................................................................................... 51 Water Quality Treatment System (Part E) ................................................................. 53 wetland hydrology protection ..................................................................................... 54 SECTION IV CONVEYANCE SYSTEM ANALYSIS AND DESIGN .............................. 58 SECTION V SPECIAL REPORTS AND STUDIES ....................................................... 61 SECTION VI OTHER PERMITS, VARIANCES AND ADJUSTMENTS ........................ 62 SECTION VII CSWPPP ANALYSIS AND DESIGN ...................................................... 63 ESC PLAN ANALYSIS AND DESIGN (PART A) ....................................................... 63 CSWPP Plan Design (Part B) .................................................................................... 63 SECTION VIII BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT ................................................................................. 65 SECTION IX OPERATIONS AND MAINTENANCE MANUAL ..................................... 66 List of Figures Figure 1 TIR Worksheet ................................................................................................ 11 Figure 2 Vicinity Map ..................................................................................................... 17 Figure 3 Drainage Basins, Subbasins, and Site Characteristics ................................... 18 Figure 4 Soils ................................................................................................................ 19 Figure 5 Downstream Map ............................................................................................ 31 Figure 6 Special Flood Areas ........................................................................................ 32 Figure 7 Stream………………………………………………………………………………...33 Page | 3 © Site Design, LLC Saleh Foundation Center Figure 8 FEMA MAP………………………………………………………………………......34 Figure 9 Basin Conditions ............................................................................................. 35 Figure 10 Drainage Complaints ..................................................................................... 36 Figure 11 Groundwater Contamination ......................................................................... 37 Figure 12 Seismic Hazards ........................................................................................... 38 Figure 13 Erosion Hazards……………………………………………………………… …...39 Figure 14 Landslide Hazards……………………………………………………………........40 Figure 15 Wetlands…………………………………………………………………………….41 Figure 16 Predevelopment Area Map............................................................................ 45 Figure 17 Post development Area Map ......................................................................... 50 Page | 4 Ó Site Design, LLC Saleh Foundation Center PROJECT OVERVIEW The subject site “Site” is located at 4108 and 41XX Jones Ave NE in NW 1/4 of NE 1/4 of Section 32, Township 24 North, Range 5 East, W.M., City of Renton, Washington. The applicant is seeking to construct a new 5-story (35,000 s.f.) mixed use building, onsite and offsite parking with driveway access from Jones Ave NE. The project Site consists of two parcels, tax parcel numbers 3345700080 and 3345700085. The existing Site area is 52,341 s.f. (1.202 ac.). The buildable area is 14,876 s.f. (0.342 ac.) after excluding wetland buffers and structure setback areas. The surrounding property zoning is CA, R- 8 and RC. The Site is bordered by residential property to the east, commercial property to the south, Jones Ave NE to the west, vacant-undeveloped property and Category III wetland ‘B’ to the north and Category III wetland ‘A’ to the south. The project proposes to remove existing gravel driveway/ parking, small shed/ vacant house, mobile structure (trailer), bushes, understory, blackberry vines, ferns and three high risk trees from the wetland buffer areas. The wetland buffer will be enhanced per the wetland buffer enhancement plan. Half street frontage improvements are proposed for Jones Ave NE with additional 4.5’ of right-of-way dedication. The net Site area after 4.5’ right-of-way dedication is 51,545 s.f. (1.183 ac.). The Site contains 32,457 s.f. (0.745 ac.) of critical area with 75’ and 56.25’ reduced buffers of an onsite wetlands ‘A’ and ‘B’, Category III Depressional Hydrogeomorphic (HGM) wetlands with wetland ‘A’ located in the southeastern portion of the Site extending offsite to the south and wetland ‘B’ in the northeast extending offsite to the north. The project will apply for a right-of-way permit, a clearing and grading and utility connection permits. The development will require permits and approvals from other regulatory agencies. Other permits include Construction Stormwater Permit from Department of Ecology, streetlight, power, gas and dry utilities. The development will also include stormwater facilities, parking under the building, landscaping and wetland buffer enhancement. The Project will meet the drainage requirements of the 2022 Renton Surface Water Design Manual (RSWDM). PREDEVELOPED SITE CONDITIONS The existing Site area contains two parcels and is approximately 52,341 s.f. (1.202 ac.). The southern portion of the property is currently developed with a mobile structure (trailer) and a small shed/ vacant house. Existing gravel driveway provides access to the Site from Jones Ave NE. The remainder of the Site is an undeveloped and undisturbed forest. Vegetation consists of bushes, understory, blackberry vines, ferns and scattered trees. The existing impervious area on the Site includes approximately 341 s.f. of small shed/ vacant house, 808 s.f. of concrete pads and pavers, 136 s.f. of rockery wall, 689 s.f. of mobile structure and 20,807 s.f. of gravel driveway and parking for a total of 22,781 s.f. (0.523 ac.). The existing gravel driveway/ parking, small shed/ vacant house, mobile structure (trailer), bushes, understory, blackberry vines, ferns and three high risk hazard trees will be removed from the wetland buffer areas will be removed from the wetland buffer areas. The wetland buffer will be enhanced per the wetland buffer enhancement plan The Site is mostly level to slightly sloping downward in multiple directions. There are local slope areas near the east property line extending downward to the west and regulated slopes greater than 40%. Page | 5 © Site Design, LLC Saleh Foundation Center In general, the Site slopes gently downward multiple directions. The property lies within the East Lake Washington – Bellevue South Drainage Basin and Cedar River/ Lake Washington watershed. The Project consists of three Threshold Discharge Area (TDA 1, TDA 2 and TDA 3) which each contain a single Natural Discharge Area (NDA 1, NDA 2 and NDA 3) and Natural Discharge Location (NDL). Project TDAs, NDAs, and NDLs are shown in Figure 3. TDA 1 is approximately 29,682 s.f. (0.681 ac), which primarily consists of northwest buildable portions of the Site and offsite half street frontage improvements on Jones Ave NE slopes northwesterly, northeasterly and northerly at an overall slope of approximately 2-3%. TDA 1 drains northwest exist the Site near northwest property corner. TDA 2 is approximately 23,258 s.f. (0.533 ac) which primarily consists of central and southeastern non -buildable sensitive areas of the Site and an offsite upstream area from backyard of property adjacent to east property line slopes in multiple directions (northerly, westerly, northeasterly, southwesterly and southeasterly at an overall slope of approximately 2- 10% and regulated slopes greater than 40% in eastern portion of the Site. TDA 2 drains onsite and offsite Category III wetland ‘A’. TDA 3 is approximately 10,830 s.f. (0.249 ac) which primarily consists of northeastern non-buildable sensitive areas of the Site and an offsite upstream area from backyard of property adjacent to east property line slopes in multiple directions (westerly, northwesterly and northeasterly at an overall slope of approximately 2-10% and regulated slopes greater than 40% in the eastern portion of the site. TDA 3 drains to onsite Category III wetland ‘B’. Runoff from northwestern buildable portion of the Site (TDA 1) drains west and northwest exit the Site across west property line and near northwest property corner which is a natural discharge location of the buildable area of the Site. The runoff travels for approximately 3,220 feet north and west through roadside ditches, public storm drainage infrastructures and classified streams and eventually discharge into Lake Washington. Runoff from Jones Ave NE right-of-way centerline along the project frontage generally flows northeast as surface flows heads north along the edge of payment flowline discharges into roadside ditch located on the east side of Jones Ave NE. The future runoff from the frontage improvements will be intercepted by proposed curb and gutter and thickened edge flowline will be collected in pipes and catch basins and to be discharged into roadside ditch located on the east side of Jones Ave NE. The downstream paths of TDA 1, TDA 2 an d TDA 3 are described in detail in the downstream analysis and downstream map. DEVELOPED SITE CONDITIONS The property is zoned Commercial Arterial (CA) and Urban Design District D overlay. The comprehensive plan land use designation is mixed-use (CMU). The applicant is seeking to construct a new 5-story (35,000 s.f.) mixed use building with onsite and offsite parking with driveway access from Jones Ave NE and utilize building and parking for religious and residential purposes where members of all ages and faith can come together. The vision for this project is to create a space that promotes spiritual growth, social cohesion, educational advancement, and c ommunity welfare. Page | 6 © Site Design, LLC Saleh Foundation Center The project Site consists of two parcels, tax parcel numbers 3345700080 and 3345700085. The existing Site area is 52,341 s.f. (1.202 ac.). The buildable area is 14,876 s.f. (0.342 ac.) after excluding wetland buffers and structure setback areas. The existing gravel driveway/ parking, small shed/ vacant house, mobile structure (trailer), bushes, understory, blackberry vines, ferns and three high risk hazard trees will be removed from the wetland buffer areas. Half street frontage improvements are proposed for Jones Ave NE with additional 4.5’ of right-of-way dedication. The project will utilize stormwater BMPs to mitigate runoff generated by new surfaces. The future 5-story building combined with access driveway and walkway will create approximately 11,820 s.f. (0.271 ac.). In option 1, the developed runoff from approximately 5,535 s.f. of roof area will be collected and conveyed to gravel filled full infiltration trench #1 and approximately 5,535 s.f. of roof runoff to be collected and conveyed to gravel filled full infiltration trench #2. Trenches #1 and 2 to be located behind the proposed building in 15’ structure setback near the edge of wetland buffer. In option 2, the entire roof area approximately 11,070 s.f. will be collected and conveyed to gravel filled full infiltration trench #3 to be located under the building garage parking. Infiltration trenches are designed for coarse sand (prescriptive trench sizing) per the geotechnical report prepared by Cobalt Geosciences, dated October 11, 2023, Section C.2.2.3 of Appendix C, and Figure C.2.2.A of 2022 RSWDM. The minimum setbacks of 10 feet from the proposed building and 5 feet from the property line will be provided. The proposed infiltration facilities (infiltration trenches) are designed to serve more than 10,000 s.f. or more of impervious surface per Section 5.2.1 of 2022 RSWDM. The remaining developed roof area of approximately 120 s.f. will be collected and conveyed to a dispersion trench #1 to maintain wetland ‘A’ hydrology for TDA 2, (3,189 s.f.) of existing drainage area that will be intercepted by the proposed building. See further details in Section III of this report. Approximately 32,457 s.f. (0.745 ac.) will be set aside as sensitive area Tract A for the onsite steep slopes, two Category III wetlands and buffers areas. The remainder of the developed Site 3,056 s.f. (0.070 ac.) will consist of landscaping and lawns. Half street right-of-way improvements in Jones Ave NE along the Site frontage will include minimum 36’ paved roadway consisting of 2 –10’ travel lanes and an 8’ parking lane, a 1.5’ concrete curb and gutter, 8’ planter strip, and 6’ concrete sidewalk. Two feet of clear space behind the sidewalk and additional 4.5’ of right-of-way dedication are provided. The improvements in Jones Ave NE will add approximately 4,911 s.f. (0.113 ac.) of impervious area and 1,280 s.f. (0.029 ac.) of pervious area. Developed surface runoff from Jones Ave NE improvements will drain northeast and northwest from the centerline to be intercepted by proposed curb & gutter and thickened edge flowline. The runoff from Jones Ave NE along frontage will be collected in proposed catch basins/ pipes will be conveyed north and to be discharged near the existing ditch located on the east side of Jones Ave NE approximately 77 feet from the Site Northwest property corner. The project will add 16,731 s.f. (0.384 ac.) of new impervious area, and 4,336 s.f. (0.100 ac.) of pervious area. The project will add 4,033 s.f. (0.093 ac.) of new pollution generating surfaces. According to Figure 1.1.2.A – Flow chart of the 2022 City of Renton Surface Water Design Manual Manual), a Full Drainage Review is required. Core Requirements # 1-9 and Special Requirements # 1-6 will be addressed. Page | 7 © Site Design, LLC Saleh Foundation Center The project will utilize stormwater BMPs to mitigate runoff generated by new surfaces. Proposed roof areas will be fully infiltrate by utilizing infiltration trenches. Cleared and landscaped areas will receive amended soil. The project meets the 0.15 cfs exemption. The Project will add less than 5,000 s.f. of new pollution generating impervious areas; therefore, water quality treatment is not required. Table 1 below outlines the new and replaced impervious and pervious surface for the project. Page | 8 © Site Design, LLC Saleh Foundation Center Project is located in Commercial Arterial (CA) zone which requires maximum lot coverage limited to 65% maximum of the lot area and 75% if parking provided within the building. The Project will result in greater than 2,000 sf of new and replace hard surface for future development and including offsite frontage improvements. The Project will add less than 5,000 s.f. of new pollution generating impervious area; therefore, water quality treatment Table 1 S.F.AC. Site area (Parcels # 3345700080 and 3345700085)52341 1.202 Site area after 4.5' ROW dedication (796 sf)796 0.018 Net Site area after ROW dedication 51545 1.183 Buildable Site area after excluding 75' buffer and 15' bldg setback areas 14876 0.342 Off-Site area (new and replaced area on Jones Ave NE)6191 0.142 Total Project buildable Area 21067 0.484 Existing Site Conditions S.F.AC. Gravel driveway and gravel parking to be removed 20807 0.478 Small shed/ Vacant house to be removed 341 0.008 Concrete pad to be removed 172 0.004 Pavers to be removed 636 0.015 Rockery wall to be removed 136 0.003 Trailer to be removed 689 0.016 Total Existing Impervious Area:22781 0.523 Total Pervious Area:29560 0.679 Developed Conditions Actual Impervious (s.f.) Modeled Impervious (s.f.) Modeled Pervious (s.f.) Proposed Buildings roof area (11,190 s.f.)) Building roof area to dispersion trench to maintain wetland 'A' hydrology 120 120 0 Building roof area to full infiltration trench #1 5535 0 5535 Building roof area to full infiltration trench #2 5535 0 5535 Concrete Walkway 270 270 0 Concrete driveway 360 360 0 Total Impervious:11700 750 Total Pervious:14126 Frontage Improvements on Jones Ave NE (6,191 s.f.) New and replaced asphalt roadway 3103 3103 0 New concrete driveway cuts 570 570 0 New concrete curb-gutter, sidewalk and sidewalk ramps 1238 1238 0 Total Impervious:4911 4911 Total Pervious:1280 S.F.AC. Total modeled Impervious:5661 0.130 Total modeled Pervious grass:15406 0.354 Total PGIS 4033 0.093 Page | 9 © Site Design, LLC Saleh Foundation Center is required. The Project will result in more than 7,000 s.f. of land disturbing activity therefore, the Project falls under Full Drainage Review. NATURAL DRAINAGE SYSTEM FUNCTIONS The project site is located within the East Lake Washington – Bellevue South Drainage Basin and Cedar River/ Lake Washington watershed. In general, the Site slopes gently downward in multiple directions. There are local slope areas near the east property line extending downward to the west with regulated slopes greater than 40%. Runoff from northwestern buildable portion of the Site drains west and northwest exit the Site across west property line and near northwest property corner which is a natural discharge location of the buildable area of the Site. The runoff travels for approximately 3,220 feet north and west through roadside ditches, public storm drainage infrastructures and classified streams and eventually discharge into Lake Washington. Runoff from Jones Ave NE right-of-way centerline along the project frontage generally flows northeast as surface flows heads north along the edge of payment flowline discharges into roadside ditch located on the east side of Jones Ave NE. The existing shallow roadside ditch along the Project frontage is to be filled. The future runoff from the frontage improvements will be intercepted by proposed curb and gutter and thickened edge flowline will be collected in pipes and catch basins and to be discharged into roadside ditch located on the east side of Jones Ave NE The Site is made up of three Natural Discharge Location (NDLs). NDA 1 discharges over the northern and western property line near northwest property corner . NDA 2 discharges over the southern property near southeastern portion of the site. NDA 3 discharges over the northern property line near the northeast property corner. A review of the SCS soils map for the area (see Figure 4, Soils) indicates No-Norma sandy loam. Per the Manual, this soil type is classified as “Till” material. The SCS Soil series descriptions follow Figure 4. Per Geotechnical report, the boring s encountered approximately 6 inches of topsoil and vegetation or gravel underlain by about 4.5 feet of loose to medium dense, fine to medium grained sand with gravel and silt (Fill). This layer was underlain by approximately 13 feet of loose to medium dense, gravel with sand trace to with silt (Alluvium). This layer was underlain by dense to very dense, fine to medium grained sand trace to with gravel (Advance Outwash), which continued to the termination depths of the bo rings. Systems could also be designed using the Coarse Sand or Gravel designation from the King County SWDM and Renton manual. The Site is bordered to the west by public right-of-way (Jones Ave NE) with shallow roadside ditch for storm drainage conveyance. Runoff from Jones Ave NE right-of-way centerline along the project frontage generally flows northeast as surface flows heads north along the edge of payment flowline discharges into roadside ditch located on the east side of Jones Ave NE. Runoff from the adjacent parcels to the north and south drains away from the Site. Upstream runoff from the backyard of parcel to the east approximately 0.54 acres enters the Site drains to onsite wetland A and B located in sensitive area Tract A. Page | 10 © Site Design, LLC Saleh Foundation Center Developed roof runoff from the new 5-story building will be collected and conveyed to gravel filled full infiltration trenches. The surface runoff from onsite driveway and frontage improvements in Jones Ave NE will be collected and conveyed to the existing downstream storm drainage systems. The project meets the 0.15 cfs exemption. The pervious area within 15 feet structure setback can sheet flow south and southeast to wetland ‘A’ as it flows to south and southeast in existing conditions. Project will implement BMP T5.13 Post-Construction Soil Quality and Depth. The majority of developed runoff from the new and replaced impervious surfaces will be infiltrated on site. Therefore, the proposed development will not create or aggravate a “severe flooding problem” or “severe erosion problem”. Page | 11 © Site Design, LLC Saleh Foundation Center FIGURE 1 TIR WORKSHEET King County Department of Development and Environmental Services TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner: Muhammad Faisal Address/Phone: 4024 Jones Ave NE Renton, WA 98056 (206) 778-8323 Project Engineer: Mohammad K. Jalalyar, P.E. Site Design, LLC Address/Phone: 8825 34th Ave NE, Suite L486 Tulalip, WA 98271 Contact: Nadeem Khan, (206) 914-1966 Project Name: Saleh Foundation Center Permit#: _______ Location: Township: 24 North Range: 05 East Section: 32 Site Address: 4108 & 41XX Jones Ave NE Renton, WA 98056 Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS Landuse (e.g., Subdivision / Short Plat / UPD Building (e.g., M/F / Commercial / SFR) Clearing and Grading Right-of-Way Use Other: DFW HPA Shoreline Management COE 404 Structural DOE Dam Safety /Rockery/Vault FEMA Floodplain ESA Section 7 COE Wetlands Other: Page | 12 © Site Design, LLC Saleh Foundation Center Part 5 PLAN AND REPORT INFORMATION Technical Information Report Full Type of Drainage Review Targeted (check one): Simplified Large Project Directed Date (include revision 08-20-25 dates): Date of Final: Site Improvement Plan (Engr. Plans) Plan Type (check Full one): Modified Simplified Date (include revision 08-20-25 dates): Date of Final: Part 6 ADJUSTMENT APPROVALS Type (circle one): Standard / Experimental / Blanket Description: (include conditions in TIR Section 2) None required or provided. Approved Adjustment No.________________________________________ Date of Approval:_________ Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: Completion Date Describe ___________________________ Re: KCSWDM Adjustment No. Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan: Green River Valley Special District Overlays: D Drainage Basin: East Lake Washington – Bellevue South Drainage Basin and Cedar River/ Lake Washington watershed. Stormwater Requirements: None Page | 13 © Site Design, LLC Saleh Foundation Center Part 9 ONSITE AND ADJACENT SENSITIVE AREAS River/ Stream Lake Wetlands Closed Depression Floodplain Other Steep Slope In general, the Site slopes gently downward in multiple directions. There are local slope areas near the east property line extending downward to the west with regulated slopes greater than 40% Erosion Hazard Landslide Hazard Coal Mine Hazard Seismic Hazard Habitat Protection Part 10 SOILS Soil Type No-Norma sandy loam Slopes 0 - 3% ______ Erosion Potential Slow to Moderate High Groundwater Table (within 5 feet) Sole Source Aquifer Other Seeps/Springs Additional Sheets Attached Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE Core Requirement #2 – Offsite Analysis Sensitive/ Critical Areas SEPA LID Infeasibility Other Additional Sheet Attached LIMITATION / SITE CONSTRAINT None Part 12 TIR SUMMARY SHEET (Provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: The Project consists of three Threshold Discharge Area Page | 14 © Site Design, LLC Saleh Foundation Center (TDA 1, TDA 2 and TDA 3) which each contain a single Natural Discharge Area (NDA 1, NDA 2 and NDA 3) and Natural Discharge Location (NDL) Core Requirements (all 9 apply): Discharge at Natural Location Number of Natural Discharge Locations: 1 Offsite Analysis Level: 1 / 2 / 3 dated: 07-02-25 Flow Control Level: 1 / 2 / 3 or Exemption Number: (include facility summary sheet) Flow Control BMPS: Full Infiltration trenches and Soil Amendments (BMP T5.13) Conveyance System Spill containment located at: Proposed CB 5 Erosion and Sediment Control/ CSWPP/CESCL/ESC Site Supervisor: TBD Construction Stormwater Contact Phone: TBD Pollution Prevention After Hours Phone: (TBD Maintenance and Operation Responsibility (circle one): Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Liability Provided: Yes / No Water Quality Type: Basic / Sens Lake / Enhanced Basic / Bog (include facility summary sheet) or exemption No. Landscape Management Plan: Yes / No Special Requirements (as applicable) Area Specific Drainage Type: CDA / SDO / MDP / BP / LMP / Shared Fac./ None Requirements Name: Floodplain/Floodway Delineation Type: (circle one): Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): Datum: Flood Protection Facilities Describe: None required or provided Source Control Describe Land use: Mixed-use (comm. / industrial land use) Describe any structural controls: None required or provided Oil Control High-use Site: Yes / No Treatment BMP: Maintenance Agreement: Yes / No with whom? Other Drainage Structures Describe: Developed roof runoff from the new 5-story building will be collected and conveyed to gravel filled full infiltration trenches. The surface runoff from onsite driveway and frontage improvements in Jones Ave NE will be collected and conveyed to the existing downstream storm drainage systems. The project meets the 0.15 cfs exemption. Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS Page | 15 © Site Design, LLC Saleh Foundation Center MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION Clearing Limits Cover Measures Perimeter Protection Traffic Area Stabilization Sediment Retention Surface Water Collection Dewatering Control Dust control Flow Control Protection of Flow Control BMP Facilities (existing and proposed) Maintain BMPs / Manage Project MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION Stabilize Exposed Surfaces Remove and Restore Temporary ESC Facilities Clean and Remove All Silt and Debris, ensure operation of Permanent Facilities, restore operation of Flow Control BMP Facilities, as necessary. Flag Limits of SAO and open space Preservation areas Other Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch Flow Control Type/Description Water Quality Type/Description Detention Infiltration Regional Facility Shared Facility Flow Control BMPs Other Full Infiltration Trenches & Dispersion Trench Infiltration and Soil amendments (BMP T5.13) Biofiltration Wetpool Media Filtration Oil Control Spill Control Flow Control BMPs Other Page | 16 © Site Design, LLC Saleh Foundation Center Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS Utility Easement Covenant Native Growth Protection Covenant Tracts: Tract A (Sensitive Area) Other: Cast in Place Vault Retaining Wall Rockery > 4’ High Structural on Steep Slope Other: Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. Signed/Date Page | 17 © Site Design, LLC Saleh Foundation Center FIGURE 2 VICINITY MAP Page | 18 © Site Design, LLC Saleh Foundation Center FIGURE 3 DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS TO P TO P TO P TO P TO P TO P TO P TO P TO P TO P TO P TO P T O P T O P T O P T O P T O P T O P TO P TO P T O E TO E TO E TO E T O E T O E TO E TO E TOE TOE SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS TO P TO P TO P TO P 0 GRAPHIC SCALE 603015 1 INCH = 30 FT. Page | 19 © Site Design, LLC Saleh Foundation Center FIGURE 4 SOILS USDA King County Soils Survey Map SITE Page | 20 © Site Design, LLC Saleh Foundation Center Page | 21 © Site Design, LLC Saleh Foundation Center Page | 22 © Site Design, LLC Saleh Foundation Center SECTION I CONDITIONS AND REQUIREMENTS SUMMARY CORE REQUIREMENTS The Project must comply with the following Core and Special Requirements: • C.R. #1 – Discharge at the Natural Location: Due to the topography of the Site, the Site is made up of three Natural Discharge Location (NDLs). NDA 1 discharges over the northern and western property line s near northwest property corner. NDA 2 discharges over the southern property near southeastern portion of the site. NDA 3 discharges over the northern property line near the northeast property corner. There are local slope areas near the east property line extending downward to the west with regulated slopes greater than 40%. The sensitive area Tract A contains NDA 2 and NDA 3 consist of steep slopes in eastern portion of the Site, two Category wetlands ‘A’ and wetland ‘B’ and wetland buffers. NDA 2 slopes in multiple directions (northerly, westerly, northeasterly, southwesterly and southeasterly at an overall slope of approximately 2-10% and regulated slopes greater than 40% in eastern portion of the Site. NDA 3 slopes in multiple directions (westerly, northwesterly and northeasterly at an overall slope of approximately 2-10% and regulated slopes greater than 40% in the eastern portion of the site. In general, the site slopes gently downward in multiple directions. The runoff travels for approximately 3,220 feet north and west through roadside ditches, public storm drainage infrastructures and classified streams and eventually discharge into Lake Washington. Runoff from Jones Ave NE right -of-way centerline along the project frontage generally flows northeast as surface flows heads north along the edge of payment flowline discharges into roadside ditch located on the east side of Jones Ave NE. Developed roof runoff from the proposed building will be collected and conveyed to gravel filled full infiltration trenches. The surface runoff from onsite driveway and frontage improvements in Jones Ave NE will be collected and conveyed to the existing downstream storm drainage system (roadside ditch) located near the northwest property which is the natural discharge location thus satisfying this requirement. • C.R. #2 – Offsite analysis: An offsite analysis is included in Section II. The analysis describes the Site’s runoff pattern in detail. • C.R. #3 – Flow Control Facilities: The Project is required to provide Level 2 Flow Control and Enhanced Basic Water Quality treatment. Flow control is required for the Site because the Project will result in greater than 2,000 sf of new and replace hard surface for future development and including offsite frontage improvements and more than 7,000 s.f. of land disturbing activity. Flow control requirements will be met for the Site by generating less than 0.15 cfs increase in 100-year, 15-minute peak runoff from the predevelopment conditions to the developed conditions per Section 1.2, of 2022 RSWDM and is therefore exempt Page | 23 © Site Design, LLC Saleh Foundation Center from providing formal flow control facilities. See Section III for a detailed hydrologic analysis. Western Washington Hydrology Model (WWHM) 2012 was used for analysis. See Section III for a detailed hydrologic analysis. Furthermore, the Project must meet the Flow Control BMP requirements as specified in Section 1.2.9 of 2022 RSWDM. The BMP requirements are further analyzed in Section III of this report. On-Site soils are not suitable for stormwater infiltration per geotechnical report by geotechnical report prepared by Cobalt Geosciences, dated October 11, 2023. C.R. #4 – Conveyance System: In this development, overflow will be drained to natural discharge point near the northwest property corner. Developed roof runoffs will be collected and conveyed by a typical catch basin/ pipe network to the proposed gravel filled full infiltration trenches to be located behind the proposed building in 15 feet structure setbacks near the edge of wetland buffer. A small roof area of proposed building, approximately 120 s.f. will be collected and conveyed to a dispersion trench #1 to maintain wetland ‘A’ hydrology for TDA 2, (3,189 s.f.) of existing drainage area that will be intercepted by the proposed building. The proposed 6-inch PVC on-Site conveyance system have been analyzed using the Manning’s Equation. See section IV of this report. The conveyance system is capable of conveying the 100-year peak storm without overtopping any structures or channels. • C.R. #5 – Construction Stormwater Pollution Prevention: The Project provides the nine minimum ESC measures. • C.R. #6 – Maintenance and Operations: Maintenance of the proposed storm drainage conveyance system including on-Site infiltration trenches, dispersion trench, Tract A will be privately maintained by the Saleh Foundation center. An Operation and Maintenance Manual is included in Section X. • C.R. #7 – Financial Guarantees: Prior to commencing construction, the Applicant must post a drainage conveyance system restoration and site stabilization financial guarantee. • C.R. #8 – Water Quality Facilities: The Project is required to provide water quality treatment if the total amount of proposed new or replaced pollution generating impervious surface (PGIS) is more than 5,000 sf. The total of effective PGIS from Jones Ave NE frontage improvements and onsite private driveway will be 4,033 s.f. and is less than 5,000 s.f., therefore water quality treatment is not required. • C.R. #9 – On -Site BMP’s: The Project must meet the Flow Control BMP requirements as specified in the Manual. BMP’s may include dispersion, restricted footprint, drywells, detention Vault and/or Page | 24 © Site Design, LLC Saleh Foundation Center pervious driveways. On-Site soils are not suitable for stormwater infiltration per geotechnical report by geotechnical report prepared by Cobalt Geosciences, dated October 11, 2023. Developed roof runoffs will be collected and conveyed to the proposed gravel filled full infiltration trenches. S.R. #1 – Other Adopted Area Specific Requirements: Not applicable for this Project. • S.R. #2 – Floodplain/Floodway Delineation: Not applicable for this Project. • S.R. #3 – Flood Protection Facilities: Not applicable for this Project. • S.R. #4 – Source Control: Not applicable for this Project. • S.R. #5 – Oil Control: Not applicable for this Project. • S.R. #6 – Aquifer Protection Area: Not applicable for this Project. Page | 25 © Site Design, LLC Saleh Foundation Center SECTION II OFF-SITE ANALYSIS Task 1: Study Area Maps King County iMap and City of Renton GIS were reviewed to determine critical areas, drainage problems, basin features, and general information about the site and surrounding areas. Figure 5: Downstream Analysis Figure 6: Special Flood Areas Figure 7: Basin Condition Figure 8: Drainage Complaints Figure 9: Groundwater Contamination Figure 10: Seismic Hazard Figure 11: Wetlands Task 2: Resource Review Section 2.3.1.1 of the Manual outlines the resource requirements for offsite analysis: • Adopted Basin Plans The property is found in the East Lake Washington – Bellevue South Drainage Basin and Cedar River/ Lake Washington watershed. The WRIA classification is Cedar- Sammamish (8). • Floodplain/ Floodway (FEMA) Maps Panel 53033C0664G of the Federal Emergency Management Agency maps shows that the site is categorized in Zone X, an area to be outside of the 500 -year floodplain. • Other Offsite Analysis Reports in the Sub-Basin No other reports were found. • Sensitive Areas Per the City of Renton’s COR Maps, there are landslide hazard or seismic hazard areas on Site. The site topography slopes in multiple directions with significant steep slopes located on the eastern portion of the property. Topography and the geotechnical report suggest the potential for a landslide should be characterized as very low as it located in undevelopable portion of the site near east property line • King County Soils Survey The soils on the Site are mapped in the Soil Survey of King County, Washington, prepared by the U.S. Department of Agriculture, Soil Conservation Service and has classified the Site as No-Norma sandy loam. Additionally, see Geotechnical Report dated October 11, 2023. Per Geotechnical report, the borings encountered Page | 26 © Site Design, LLC Saleh Foundation Center approximately 6 inches of topsoil and vegetation or gravel underlain by about 4.5 feet of loose to medium dense, fine to medium grained sand with gravel and silt (Fill). This layer was underlain by approximately 13 feet of loose to medium dense, gravel wi th sand trace to with silt (Alluvium). This layer was underlain by dense to very dense, fine to medium grained sand trace to with gravel (Advance Outwash), which continued to the termination depths of the borings. • Wetlands Inventory Maps According to the Wetland report, Wetlands A and B are both Category III Depressional Hydrogeomorphic (HGM) wetlands with Wetland A located in the southeastern portion of the Site extending offsite to the south and Wetland B in the northeast extending offsite to the north. See the Wetland Assessment report for more information. • Clean Water Act Section 303d List of Polluted Waters No polluted waters were found. • City of Renton Erosion and Landslide Maps The Natural Resources Conservation Services (NRCS) maps for King County indicate that the site is underlain by Norma sandy loam. These soils would have a slight to moderate erosion potential in a disturbed state depending on the slope magnitude. There could be a short-term increase in the potential for on-site erosion where soils are exposed during site preparation and construction; however, the Project will comply with all applicable erosion control measures, short term and long term per geotechnical report recommendations. Task 3: Field Inspection The upstream and downstream areas were reviewd utilizing available maps. A. Upstream Tributary Area In evaluating the upstream area, we reviewed the USGS topographic survey mapping of the area, a field topographic survey, and conducted field reconnaissance. The Site is bordered by residential properties to the east and south, Jones Ave NE to the west, vacant-undeveloped property and Category III wetland B to the north and a Category III wetland A to the south. Runoff from Jones Ave NE right-of-way centerline along the project frontage generally flows northeast as surface flows heads north along the edge of payment flowline discharges into roadside ditch located on the east side of Jones Ave NE. Runoff from the adjacent parcels to the north and south drains away from the Site. Upstream runoff from the backyard of parcel to the east approximately 0.54 acres enters the Site drains to onsite wetland A and B located in sensitive area Tract A. Page | 27 © Site Design, LLC Saleh Foundation Center B. Downstream Analysis A field investigation was conducted on July 07, 2025 which covered the Site and conveyance system a quarter mile downstream of the Site. The weather was mostly sunny. Runoff was visible in parts of the downstream conveyance system. Based on field reconnaissance, review of available topographic data, aerial photography, it appears that the Project Site has three Threshold Discharge Area (TDA 1, TDA 2 and TDA 3) with three Natural Discharge Area (NDA 1, NDA 2 and NDA 3) and Natural Discharge Location (NDL). Project TDAs, NDAs, and NDLs are shown in Figure 3. TDA 1 is approximately 29,682 s.f. (0.681 ac), which primarily consists of northwest buildable portions of the Site and offsite half street frontage improvements on Jones Ave NE slopes northwesterly, northeasterly and northerly at an overall slope of appro ximately 2-3%. TDA 1 drains northwest exist the Site near northwest property corner. TDA 2 is approximately 23,258 s.f. (0.533 ac) which primarily consists of central and southeastern non-buildable sensitive areas of the Site and an offsite upstream area f rom backyard of property adjacent to east property line slopes in multiple directions (northerly, westerly, northeasterly, southwesterly and southeasterly at an overall slope of approximately 2 - 10% and regulated slopes greater than 40% in eastern portion o f the Site. TDA 2 drains to onsite and offsite Category III wetland ‘A’. TDA 3 is approximately 10,830 s.f. (0.249 ac) which primarily consists of northeastern non -buildable sensitive areas of the Site and an offsite upstream area from backyard of property adjacent to east property line slopes in multiple directions (westerly, northwesterly and northeasterly at an overall slope of approximately 2-10% and regulated slopes greater than 40% in the eastern portion of the site. TDA 3 drains to onsite Category III wetland ‘B’. The Site is made up of three Natural Discharge Location (NDLs). NDA 1 discharges over the northern and western property line near northwest property corner. NDA 2 discharges over the southern property near southeastern portion of the site. NDA 3 discharges over the northern property line near the northeast property corner. The downstream paths of NDA 1, NDA 2 and NDA 3 are described in detail below. During the field investigation, there were no problems observed at the time of the field reconnaissance. TDA 1 (NDA 1 DOWNSTREAM PATH): The natural discharge location of the northwest buildable portion of the Site (NDA 1) is located near the northwest property corner. Runoff drains northwest exit the Site as sheet flow across north and west property lines and near northwest property corner. Runoff from Jones Ave NE right-of-way centerline along the project frontage flows northeast as surface flows heads north along the edge of payment flowline discharges into roadside ditch located on the east side of Jones Ave NE and heads north through the ditch. The following is a discussion of the 1/4 mile downstream from the discharge location of the project. Point “A1” is the natural discharge point (NDL) of the Site on the downstream map. (±0’) Page | 28 © Site Design, LLC Saleh Foundation Center From Point “A1” to Point “A2”, runoff continues northwest as surface flow over the pervious surface for approximately 12 feet enters into a shallow roadside ditch located on the east side of Jones Ave NE. (±12’) From Point “A2” to Point “A3”, runoff heads east as an open channel flow through shallow grass lined ditch (1.5’ bottom width and 4.5’ wide) for approximately 78 feet enters into a 12” LCPE pipe. (±90) From Point “A3” to Point “A4”, runoff continues north as pipe flow through 12” LCPE pipe for approximately 29 feet discharges into a roadside ditch located on the east side of Jones Ave NE. (119’) From Point “A4” to Point “A5”, runoff heads north as an open channel flow through shallow ditch (2’ bottom width and 5’ wide) for approximately 74 feet enters into a 12” LCPE pipe. (±193) From Point “A5” to Point “A6”, runoff continues north as pipe flow through 12” LCPE pipe for approximately 121 feet enters into a Type 1 CB located on the east side of Jones Ave NE. (314’) From Point “A6” to Point “A7”, runoff heads north as pipe flow through 12” LCPE pipe for approximately 187 feet enters into a Type 1 CB located on the east side of Jones Ave NE. (501’) From Point “A7” to Point “A8”, runoff heads north as pipe flow through 1 8” Concrete pipe for approximately 252 feet enters into a Type 2 CB located on the east side of Jones Ave NE. (753’) From Point “A8” to Point “A9”, runoff heads north as pipe flow through 18” Concrete pipe for approximately 81 feet enters into a Type 2 CB located on the east side of Jones Ave NE. (834’) From Point “A9” to Point “A10”, runoff heads northeast as pipe flow through 18” Concrete pipe for approximately 30 feet enters into a Type 2 CB located on the south side of NE 43rd St. (864’) From Point “A10” to Point “A11”, runoff heads northwest as pipe flow through 24” CMP culvert for approximately 63 feet under NE 43rd St discharges into a stream located on the east margin of I-405 right-of-way line. (927’) From Point “A11” to Point “A12”, runoff heads north as an open channel flow through stream for approximately 372 feet enters into a 24” CMP culvert. (±1,299) From Point “A12” to Point “A13”, runoff heads northwest as pipe flow through 24” CMP culvert for approximately 164 feet under NE 44th St discharges into a stream located on the east margin of I-405 right-of-way line. (1,463’) From Point “A13” to Point “A14”, runoff heads north as an open channel flow through stream for approximately 208 feet discharges into a pond. (±1,671) From Point “A14” to Point “A15”, runoff heads north as an open channel flow through pond for approximately 197 feet discharges into a 24” pipe outlet pipe. Pipe material unknown. (±1,868) Page | 29 © Site Design, LLC Saleh Foundation Center From Point “A15” to Point “A16”, runoff heads north and west through existing storm drainage infrastructures and stream for approximately 1,352 feet discharges into Lake Washington. (±3,220) Downstream analysis was terminated at Point “A16” which is approximately ±3,220 feet from the Site natural discharge location. The downstream is detailed in the Downstream Map. TDA 2 (NDA 2 DOWNSTREAM PATH): The natural discharge location of the non-buildable sensitive area portion of the Site (NDA 2) is located at southern property near southeastern portion of the Site. Runoff drains to onsite Category III wetland ‘B’ located in the northeastern portion of the Site. The following is a discussion of the 1/4 mile downstream from the discharge location of the project. Point “B1” is the natural discharge point (NDL) of the Site on the downstream map. (±0’) From Point “B1” to Point “B2”, runoff continues south, west, northwest and southwest through wetlands, existing storm drainage infrastructures and May Creek for approximately 3,472 feet discharges into Lake Washington. (±3,472). Downstream analysis was terminated at Point “B2”. The downstream is detailed in the Downstream Map. TDA 3 (NDA 3 DOWNSTREAM PATH): The natural discharge location of the non-buildable sensitive area portion of the Site (NDA 3) is located at northern property line near the northeast property corner of the Site. Runoff drains to onsite and offsite Category III wetland ‘A’ located in the southeastern portion of the Site. The following is a discussion of the 1/4 mile downstream from the discharge location of the project. Point “C1” is the natural discharge point (NDL) of the Site on the downstream map. (±0’) From Point “C1” to Point “A3”, runoff continues northwest, west, and north through wetland and ditch located offsite on adjacent parcel to north for approximately 287 feet enters into a 12” LCPE pipe located on the east side of Jones Ave NE (±387). At Point “A3”, the downstream path merge with TDA 1 downstream path. Downstream analysis was terminated at Point “A3”. The downstream is detailed in the Downstream Map. No significant drainage related impacts to the downstream system are anticipated or expected to result from the project. Trickle flow was observed. No overtopping, flooding, ponding, and sedimentation were observed during the 1/2-mile downstream field investigation. Task 5: Mitigation of Existing or Potential Problems The analysis did not produce any observed or documented concerns regarding the downstream system. The mitigation measures described in Section 4 will not create or exacerbate any existing problems within the downstream drainage corridor. Page | 30 © Site Design, LLC Saleh Foundation Center C. Downstream Concerns & Effects A review of the King County Water and Land Resources Division – Drainage Services Section Documented Drainage Complaints within one-quarter mile of the downstream flow path for the buildable portion of (TDA 1) revealed no drainage complaints within the last ten years. This project is not discharging into a wetland, therefore an evaluation of a type 4 drainage problem, or any possible impacts to wetlands or critical areas are not required. The downstream analysis discussed in this section has provided detailed information that there will be no additional impact on runoff quantity, or water quality on the existing wetlands. Page | 31 © Site Design, LLC Saleh Foundation Center FIGURE 5 DOWNSTREAM MAP 0 GRAPHIC SCALE 450300150 1 INCH = 300 FT. Page | 32 © Site Design, LLC Saleh Foundation Center FIGURE 6 SPECIAL FLOOD AREAS Page | 33 © Site Design, LLC Saleh Foundation Center FIGURE 7 STREAMS Page | 34 © Site Design, LLC Saleh Foundation Center FIGURE 8 FEMA MAP Page | 35 © Site Design, LLC Saleh Foundation Center FIGURE 9 BASIN CONDITIONS Page | 36 © Site Design, LLC Saleh Foundation Center FIGURE 10 DRAINAGE COMPLAINTS Page | 37 © Site Design, LLC Saleh Foundation Center FIGURE 11 GROUNDWATER CONTAMINATION Page | 38 © Site Design, LLC Saleh Foundation Center FIGURE 12 SEISMIC HAZARDS Page | 39 © Site Design, LLC Saleh Foundation Center FIGURE 13 EROSION HAZARDS Page | 40 © Site Design, LLC Saleh Foundation Center FIGURE 14 LANDSLIDE HAZARDS Page | 41 © Site Design, LLC Saleh Foundation Center FIGURE 15 WETLANDS Page | 42 © Site Design, LLC Saleh Foundation Center See Wetland Assessment report for detailed information. Page | 43 © Site Design, LLC Saleh Foundation Center SECTION III FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN EXISTING SITE HYDROLOGY (PART A) Western Washington Hydrology Model (WWHM) 2012 was used to model runoff from the Site. The Site was modeled as predeveloped forest conditions for target surfaces (See Figure 12). Per Table 3.2.2.A of the 2022 RSWDM, the soil type is modeled as “Till”, hydrologic soil group D for the No-Norma sandy loam, SCS classification per the Per the SCS King County Soil Survey. Per Geotechnical report, the borings encountered approximately 6 inches of topsoil and vegetation or gravel underlain by about 4.5 feet of loose to medium dense, fine to medium grained sand with gravel and silt (Fill). This layer was underlain by approximately 13 feet of loose to medium dense, gravel with sand trace to with silt (Alluvium). This layer was underlain by dense to very dense, fine to medium grained sand trace to with gravel (Advance Outwash), which continued to the termination depths of the borings. Per the Geotechnical report, Coarse Sand or Gravel found on the Site, the entire buildable portion of Site is modeled as “A/B, Forest, Flat”. Results of the WWHM analysis are included in this section. WWHM Input S.F.AC. Pre-developed Basin Modeled as A/B Forest, Flat 21067 0.484 Impervious 0 Total 21067 0.484 Page | 44 © Site Design, LLC Saleh Foundation Center Modeling Input for the Pre-Developed Site Page | 45 © Site Design, LLC Saleh Foundation Center FIGURE 16 PREDEVELOPMENT AREA MAP TO P TO P TO P TO P TO P TO P TO P TO P TO P TO P TO P TO P T O P T O P T O P T O P T O P T O P TO P TO P T O E TO E TO E TO E T O E T O E TO E TO E TOE TOE SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS TO P TO P TO P TO P 0 GRAPHIC SCALE 603015 1 INCH = 30 FT. Page | 46 © Site Design, LLC Saleh Foundation Center DEVELOPED SITE HYDROLOGY (PART B) Developed Site Area Hydrology Soil Type The soil types are unchanged from predeveloped conditions. Land Cover The portions of the Site within the developable area were modeled as “Pervious Grass”, and “Impervious” as appropriate with soil amendments per BMP T5.13. In order to accurately model the developed site hydrology, considerations were made for the Site. The Site has been modeled with the maximum lot coverage limited to 65% maximum of the lot area and 75% if parking provided within the building. The project will also utilize small lot BMP requirements; use of gravel filled trenches for full infiltration of roof runoff. The future 5-story building combined with access driveway and walkway will create approximately 11,820 s.f. (0.271 ac.). In option 1, the developed runoff from approximately 5,535 s.f. of roof area will be collected and conveyed to gravel filled full infiltration trench #1 and approximately 5,535 s.f. of roof runoff to be collected and conveyed to gravel filled full infiltration trench #2. Trenches #1 and 2 to be located behind the proposed building in 15’ structure setback near the edge of wetland buffer. In option 2, the entire roof area approximately 11,070 s.f. will be collected and conveyed to gravel filled full infiltration trench #3 to be located under the building garage parking. Infiltration trenches are designed for coarse sand (prescriptive tre nch sizing) per the geotechnical report prepared by Cobalt Geosciences, dated October 11, 2023, Section C.2.2.3 of Appendix C, and Figure C.2.2.A of 2022 RSWDM. The minimum setbacks of 10 feet from the proposed building and 5 feet from the property line w ill be provided. The proposed infiltration facilities (infiltration trenches) are designed to serve more than 10,000 s.f. or more of impervious surface per Section 5.2.1 of 2022 RSWDM. Trench Sizing Infiltration trenches are designed for coarse sand (prescriptive trench sizing) per the geotechnical report prepared by Cobalt Geosciences, dated October 11, 2023, Section C.2.2.3 of Appendix C, and Figure C.2.2.A of 2022 RSWDM. Per Section C2.2.3, minimum trench size is 2 feet wide and 2 feet deep. The proposed trench width is 5 feet with shorter trench length was used. Both trench sizing will provide the same amount of storage volume. Option 1: Infiltration Trench # 1 Impervious Area: 5,535 s.f. Required Trench Length: 110.7 feet Min. Trench Width: 2 feet Effective Depth: 2.6 feet Proposed Trench Width: 5 feet Proposed Trench Length: 35 feet Page | 47 © Site Design, LLC Saleh Foundation Center Volume Required: Length x Width x Depth = 110.7 x 2 x 2 = 442.8 cu.ft. Volume Provided: 35 x 5 x 2.6 = 455 cu.ft. Option 1: Infiltration Trench # 2 Impervious Area: 5,535 s.f. Required Trench Length: 110.7 feet Min. Trench Width: 2 feet Effective Depth: 2.6 feet Proposed Trench Width: 5 feet Proposed Trench Length: 35 feet Volume Required: Length x Width x Depth = 110.7 x 2 x 2 = 442.8 cu.ft. Volume Provided: 35 x 5 x 2.6 = 455 cu.ft. Option 2: Infiltration Trench # 3 Impervious Area: 11,070 s.f. Required Trench Length: 221.4 feet Min. Trench Width: 2 feet Effective Depth: 3 feet Proposed Trench Width: 5 feet Proposed Trench Length: 60 feet Volume Required: Length x Width x Depth = 221.4 x 2 x 2 = 885.6 cu.ft. Volume Provided: 60 x 5 x 3 = 900 cu.ft. Dispersion Trench #1: (to maintain wetland ‘A’ hydrology) 10’ long x 2’ wide x 2’ deep gravel filled dispersion trench to disperse 120 s.f. of roof area. Results of the WWHM analysis are included in this section. WWHM Input S.F.AC. Pre-developed Basin Modeled as A/B Forest, Flat 21067 0.484 Impervious 0 Total 21067 0.484 Developed Basin Impervious Building Roofs 120 0.003 Roads 3103 0.071 Concrete curb-gutter, sidewalk, walkway and sidewalk ramps 1508 0.035 Driveways 930 0.021 Total Impervious 5661 0.130 Total Pervious 15406 0.354 Total PGIS 4033 0.093 Page | 48 © Site Design, LLC Saleh Foundation Center Modeling Input for the Post-Developed Site Page | 49 © Site Design, LLC Saleh Foundation Center Page | 50 © Site Design, LLC Saleh Foundation Center FIGURE 17 POST DEVELOPMENT AREA MAP SSS SSS TO P TO P TO P TO P TO P TO P TO P TO P TO P TO P TO P TO P T O P T O P T O P T O P T O P T O P TO P TO P T O E TO E TO E TO E T O E T O E TO E TO E TOE TOE SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS TO P TO P TO P TO P 0 GRAPHIC SCALE 603015 1 INCH = 30 FT. Page | 51 © Site Design, LLC Saleh Foundation Center PERFORMANCE STANDARDS (PART C) The Project is required to adhere to Level 2 Flow Control and Enhanced Basic Water Quality Treatment area. The Level 2 performance criteria requires that the developed condition’s durations must match the predeveloped durations ranging from 50% of the two-year peak flow up to the full 50-year peak flow and match developed peak discharge rates to predeveloped peak discharge rates for the 2-year and 10-year return periods (2022 RSWDM, Sec. 1.2.3.1). The Project will add less than 5,000 sf of new PGIS. Therefore, a formal water quality treatment facility is not required. Conveyance criteria for the Project require that all new pipes be designed to convey and contain (at minimum) the 25-year peak flow. FLOW CONTROL SYSTEM (PART D) The flow control requirements will be met by infiltrating developed roof runoff utilizing infiltration facilities and meeting 0.15 cfs exemption. See Section III for a detailed Page | 52 © Site Design, LLC Saleh Foundation Center Flow Control BMP Selection Per Section 1.2.9 of the 2017 RSWDM which states that Flow Control BMPs must be implemented for mitigation. The Project is required to evaluate the feasibility and applicability of dispersion, infiltration, and other stormwater LID options. On-Site soils are suitable for stormwater infiltration per the geotechnical report. Developed roof runoff from the new building will be collected and conveyed to gravel filled full infiltration trenches. Infiltration trenches are designed for coarse sand (prescriptive trench sizing) per the geotechnical report prepared by Cobalt Geoscienc es, dated October 11, 2023, Section C.2.2.3 of Appendix C, and Figure C.2.2.A of 2022 RSWDM. Amended soil will be used per BMP T5.13. Roofs: 1. Full dispersion is not feasible because the minimum 100’ vegetated flowpath cannot be provided due to lot size, sensitive area and buffers, three drainage basins, slopes in multiple directions and limited buildable area. 2. Downspout limited dispersion systems are not feasible because the minimum 25’ vegetated flowpath cannot be provided due to lot size, sensitive area and buffers, three drainage basins, slopes in multiple directions and limited buildable area. 3. Bioretention cells and rain gardens are not feasible due to lot size, sensitive area and buffers, three drainage basins, slopes in multiple directions and limited buildable area. 4. Downspout full infiltration systems are feasible due to soil type per geotechnical report by Cobalt Geosciences, dated October 11, 2023. 5. Perforated stub-out connections are feasible due to soil type per the geotechnical report prepared by Cobalt Geosciences, dated October 11, 2023. Driveways: 1. Full dispersion is not feasible because the minimum 100’ vegetated flowpath cannot be provided due to lot size, sensitive area and buffers, three drainage basins, slopes in multiple directions and limited buildable area. 2. Sheet flow dispersion systems are not feasible because the minimum vegetated flowpath cannot be provided due to lot size, sensitive area and buffers, three drainage basins, slopes in multiple directions and limited buildable area. 3. Bioretention cells and rain gardens are not feasible due to lot size, sensitive area and buffers, three drainage basins, slopes in multiple directions and limited buildable area. 4. Concentrated flow dispersion is not feasible because the minimum 50’ vegetated flowpath cannot be provided due to lot size, sensitive area and buffers, three drainage basins, slopes in multiple directions and limited buildable area. Page | 53 © Site Design, LLC Saleh Foundation Center Lawn and Landscaped Areas: The soil moisture holding capacity of new pervious surfaces must be protected in accordance with KCC 16.82.100 (F) and (G). KCC 16.82.100(F) requires that the duff layer or native topsoil be retained to the maximum extent practicable. KCC 16.82.100(G) requires soil amendment to mitigate for lost moisture holding capacity where compaction or removal of some or all the duff layer or underlying topsoil has occurred. Soil amendment will be accomplished by tilling three inches of compost eight inches into disturbed soil in the areas of planting beds or by tilling two inches of compost eight inches into disturbed soil in the areas of lawn turf. Two to four inches of arborist wood chip, coarse bark mulch, or compost mulch shall be added to planting beds after fina l planting. WATER QUALITY TREATMENT SYSTEM (PART E) The Project is required to provide water quality treatment as the total amount of new on- Site pollution generating impervious surface (PGIS) is more than 5,000 sf. The total of effective PGIS from Jones Ave NE frontage improvements and onsite private driveway will be 4,033 s.f. and is less than 5,000 s.f., therefore water quality treatment is not required. Page | 54 © Site Design, LLC Saleh Foundation Center WETLAND HYDROLOGY PROTECTION This requirement is generally intended to maintain the existing hydrologic conditions to on-site and nearby wetlands to the greatest practical extent. It requires per section 1.2.2.1.1 and reference section 5 of 2022 RSWDM which describes the requirement and mitigation measures. Reference 5 is excerpted from the Washington State Department of Ecology's 2019 Stormwater Management Manual for Western Washington (SMMWW). The project does not intend to utilize the onsite wetland as a treatment or flow control facility. Wetland Hydroperiod Protection Per Reference 5, the Wetland Hydroperiod Protection is separated into two methods (Methods 1 and 2) that are dependent on the wetland category, and whether the project proponent has legal access to the wetland. The first method requires a minimum one year of monitoring followed by continuous simulation modeling of the wetland stage (called Method 1). Method 1 shall be applied to the wetlands Category I or II that the project proponent owns, or the project proponent has legal access to - for purposes of conducting monitoring in the wetland. Method 1 takes into account wetland specific information and field data; therefore, it allows more detailed evaluation of effects of stormwater on wetland functions. In cases wh ere the project proponent neither owns nor has legal access to the Category I or II wetlands receiving stormwater from a proposed project, Method 2 shall be used. Method 2 uses a site discharge volume model to evaluate hydrologic changes in a wetland, with no additional wetland monitoring requirement. Method 2 will be applied to the onsite and offsite Category III wetland ‘A’. Development of the Site in northwest buildable portion will not change the hydrologic contributions to the onsite wetlands due to separate drainage basin (TDA 1) in buildable portion of the Site which drains away from the onsite wetlands. The Project consists of three Threshold Discharge Area (TDA 1, TDA 2 and TDA 3) which each contain a single Natural Discharge Area (NDA 1, NDA 2 and NDA 3) and Natural Discharge Location (NDL). Project TDAs, NDAs, and NDLs are shown in Figure 3. The Site is made up of three Natural Discharge Location (NDLs). NDA 1 discharges over the northern and western property line near northwest property corner. NDA 2 discharges over the southern property near southeastern portion of the site. NDA 3 discharges over the northern property line near the northeast property corner. As shown in Figure 3, there is approximately 3,189 s.f. (0.073 ac) of TDA 2 existing drainage to be intercepted by the proposed building. More likely the existing intercepted drainage will drain back to its natural drainage patterns south and southwest towards wetland ‘A’ by minor grading in 15’ structural setback areas, therefore there will be a minor or no loss in wetland ‘A’ hydrology due to proposed development. The project will attempt to maintain the hydrologic contributions to the onsite wetland to the greatest practical extent. Small area from new roof of approximately 120 s.f. will be collected and conveyed to a dispersion trench #1 to maintain wetland ‘A’ hydrology for TDA 2, (3,189 s.f.) of existing drainage area that will be intercepted by the proposed building. Page | 55 © Site Design, LLC Saleh Foundation Center The analysis performed using WWHM hydrologic modeling software . For this analysis, the existing Site conditions (TDA 2) areas were assumed to be a forested condition. For the developed condition, 120 s.f of roof area is modeled as being tributary to the wetland ‘A’ to be discharged to the wetland ‘A’ via a 10’ long dispersal trench. The wetland hydroperiod analysis for the proposed scenario is provided in this Section. Page | 56 © Site Design, LLC Saleh Foundation Center WWHM Analysis Reports 0.15 cfs Exemption WWHM2012 PROJECT REPORT wwhm 8/12/2025 3:11:46 PM Page 2 General Model Information WWHM2012 Project Name:wwhm Site Name:Saleh Foundation Community Center Site Address:4018 Jones Ave NE City:Renton, WA 98056 Report Date:8/12/2025 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2023/03/31 Version:4.2.19 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year wwhm 8/12/2025 3:11:46 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre A B, Forest, Flat 0.484 Pervious Total 0.484 Impervious Land Use acre Impervious Total 0 Basin Total 0.484 wwhm 8/12/2025 3:11:46 PM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre A B, Lawn, Flat 0.354 Pervious Total 0.354 Impervious Land Use acre ROADS FLAT 0.071 ROOF TOPS FLAT 0.003 DRIVEWAYS FLAT 0.021 SIDEWALKS FLAT 0.035 Impervious Total 0.13 Basin Total 0.484 wwhm 8/12/2025 3:11:46 PM Page 5 Routing Elements Predeveloped Routing wwhm 8/12/2025 3:11:46 PM Page 6 Mitigated Routing wwhm 8/12/2025 3:11:46 PM Page 7 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.484 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.354 Total Impervious Area:0.13 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000411 5 year 0.000622 10 year 0.000793 25 year 0.001051 50 year 0.001276 100 year 0.001531 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.051782 5 year 0.070549 10 year 0.084918 25 year 0.105428 50 year 0.122522 100 year 0.141264 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.066 1950 0.001 0.085 1951 0.001 0.051 1952 0.000 0.036 1953 0.000 0.039 1954 0.000 0.044 1955 0.000 0.046 1956 0.000 0.045 1957 0.000 0.051 1958 0.000 0.041 wwhm 8/12/2025 3:12:11 PM Page 8 1959 0.000 0.042 1960 0.000 0.045 1961 0.000 0.044 1962 0.000 0.038 1963 0.000 0.044 1964 0.000 0.042 1965 0.000 0.055 1966 0.000 0.035 1967 0.000 0.080 1968 0.000 0.069 1969 0.000 0.048 1970 0.000 0.046 1971 0.000 0.055 1972 0.002 0.079 1973 0.000 0.034 1974 0.000 0.050 1975 0.000 0.058 1976 0.000 0.040 1977 0.000 0.042 1978 0.000 0.052 1979 0.000 0.071 1980 0.000 0.063 1981 0.000 0.052 1982 0.000 0.073 1983 0.000 0.059 1984 0.000 0.038 1985 0.000 0.052 1986 0.000 0.045 1987 0.000 0.069 1988 0.000 0.042 1989 0.000 0.052 1990 0.000 0.160 1991 0.001 0.089 1992 0.000 0.037 1993 0.000 0.032 1994 0.000 0.035 1995 0.000 0.046 1996 0.003 0.074 1997 0.000 0.056 1998 0.000 0.048 1999 0.001 0.102 2000 0.000 0.049 2001 0.000 0.054 2002 0.000 0.063 2003 0.000 0.051 2004 0.000 0.092 2005 0.000 0.042 2006 0.000 0.045 2007 0.004 0.163 2008 0.000 0.090 2009 0.000 0.064 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0040 0.1634 2 0.0027 0.1597 3 0.0020 0.1024 wwhm 8/12/2025 3:12:11 PM Page 9 4 0.0007 0.0922 5 0.0007 0.0895 6 0.0006 0.0893 7 0.0006 0.0845 8 0.0004 0.0796 9 0.0004 0.0793 10 0.0004 0.0737 11 0.0004 0.0731 12 0.0004 0.0706 13 0.0004 0.0691 14 0.0004 0.0689 15 0.0004 0.0658 16 0.0004 0.0641 17 0.0004 0.0634 18 0.0004 0.0628 19 0.0004 0.0595 20 0.0004 0.0579 21 0.0004 0.0560 22 0.0004 0.0553 23 0.0004 0.0551 24 0.0004 0.0538 25 0.0004 0.0524 26 0.0004 0.0518 27 0.0004 0.0517 28 0.0004 0.0516 29 0.0004 0.0511 30 0.0004 0.0509 31 0.0004 0.0506 32 0.0004 0.0503 33 0.0004 0.0495 34 0.0004 0.0481 35 0.0004 0.0479 36 0.0004 0.0462 37 0.0004 0.0459 38 0.0004 0.0457 39 0.0004 0.0452 40 0.0004 0.0451 41 0.0004 0.0449 42 0.0004 0.0448 43 0.0004 0.0442 44 0.0004 0.0442 45 0.0004 0.0436 46 0.0004 0.0423 47 0.0004 0.0422 48 0.0004 0.0422 49 0.0004 0.0420 50 0.0004 0.0417 51 0.0004 0.0412 52 0.0004 0.0397 53 0.0004 0.0385 54 0.0004 0.0380 55 0.0004 0.0378 56 0.0004 0.0371 57 0.0004 0.0359 58 0.0003 0.0355 59 0.0003 0.0352 60 0.0003 0.0344 61 0.0003 0.0322 wwhm 8/12/2025 3:12:11 PM Page 10 wwhm 8/12/2025 3:12:11 PM Page 11 Duration Flows The Duration Matching Failed Flow(cfs)Predev Mit Percentage Pass/Fail 0.0002 3044 314415 10329 Fail 0.0002 2712 309924 11427 Fail 0.0002 2387 305646 12804 Fail 0.0002 2156 302010 14007 Fail 0.0002 1921 298160 15521 Fail 0.0003 1689 294524 17437 Fail 0.0003 1479 290888 19667 Fail 0.0003 1328 287465 21646 Fail 0.0003 1170 284471 24313 Fail 0.0003 1016 281477 27704 Fail 0.0003 843 278482 33034 Fail 0.0003 674 275702 40905 Fail 0.0003 552 272921 49442 Fail 0.0003 442 270141 61117 Fail 0.0004 355 267788 75433 Fail 0.0004 254 265221 104417 Fail 0.0004 134 262868 196170 Fail 0.0004 36 260516 723655 Fail 0.0004 26 258163 992934 Fail 0.0004 26 256024 984707 Fail 0.0004 26 253885 976480 Fail 0.0004 26 251746 968253 Fail 0.0004 25 249821 999284 Fail 0.0005 25 247682 990728 Fail 0.0005 24 245757 1023987 Fail 0.0005 23 243832 1060139 Fail 0.0005 23 242121 1052700 Fail 0.0005 23 240196 1044330 Fail 0.0005 22 238485 1084022 Fail 0.0005 22 236560 1075272 Fail 0.0005 22 235063 1068468 Fail 0.0005 21 233352 1111200 Fail 0.0006 21 231855 1104071 Fail 0.0006 21 230143 1095919 Fail 0.0006 21 228646 1088790 Fail 0.0006 19 227149 1195521 Fail 0.0006 19 225652 1187642 Fail 0.0006 18 224155 1245305 Fail 0.0006 18 222657 1236983 Fail 0.0006 17 221374 1302200 Fail 0.0006 16 219877 1374231 Fail 0.0006 16 218594 1366212 Fail 0.0007 16 217310 1358187 Fail 0.0007 16 215813 1348831 Fail 0.0007 16 214530 1340812 Fail 0.0007 15 213268 1421786 Fail 0.0007 15 212113 1414086 Fail 0.0007 15 210872 1405813 Fail 0.0007 14 209696 1497828 Fail 0.0007 13 208370 1602846 Fail 0.0007 13 207193 1593792 Fail 0.0008 13 206124 1585569 Fail 0.0008 13 204926 1576353 Fail 0.0008 13 203750 1567307 Fail wwhm 8/12/2025 3:12:11 PM Page 12 0.0008 13 202616 1558584 Fail 0.0008 12 201482 1679016 Fail 0.0008 12 200392 1669933 Fail 0.0008 12 199429 1661908 Fail 0.0008 11 198424 1803854 Fail 0.0008 11 197248 1793163 Fail 0.0009 11 196221 1783827 Fail 0.0009 11 195194 1774490 Fail 0.0009 10 194253 1942530 Fail 0.0009 10 193226 1932260 Fail 0.0009 9 192200 2135555 Fail 0.0009 9 191237 2124855 Fail 0.0009 9 190275 2114166 Fail 0.0009 9 189441 2104900 Fail 0.0009 9 188542 2094911 Fail 0.0010 8 187644 2345550 Fail 0.0010 8 186746 2334325 Fail 0.0010 8 185805 2322562 Fail 0.0010 8 184863 2310787 Fail 0.0010 8 184008 2300100 Fail 0.0010 8 183152 2289400 Fail 0.0010 8 182275 2278437 Fail 0.0010 8 181398 2267475 Fail 0.0010 8 180521 2256512 Fail 0.0010 8 179751 2246887 Fail 0.0011 8 178896 2236200 Fail 0.0011 8 178062 2225775 Fail 0.0011 8 177270 2215875 Fail 0.0011 8 176479 2205987 Fail 0.0011 8 175752 2196900 Fail 0.0011 8 175025 2187812 Fail 0.0011 8 174212 2177650 Fail 0.0011 8 173442 2168025 Fail 0.0011 8 172672 2158400 Fail 0.0012 8 171902 2148775 Fail 0.0012 8 171196 2139950 Fail 0.0012 8 170469 2130862 Fail 0.0012 8 169742 2121775 Fail 0.0012 8 168972 2112150 Fail 0.0012 8 168244 2103050 Fail 0.0012 8 167560 2094500 Fail 0.0012 8 166833 2085412 Fail 0.0012 8 166105 2076312 Fail 0.0013 8 165421 2067762 Fail 0.0013 8 164694 2058675 Fail 0.0013 8 164009 2050112 Fail The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 50% of the flows for the range of the duration analysis. wwhm 8/12/2025 3:12:11 PM Page 13 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0.0664 acre-feet On-line facility target flow:0.0878 cfs. Adjusted for 15 min:0.0878 cfs. Off-line facility target flow:0.0496 cfs. Adjusted for 15 min:0.0496 cfs. wwhm 8/12/2025 3:12:11 PM Page 14 LID Report wwhm 8/12/2025 3:12:19 PM Page 15 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. wwhm 8/12/2025 3:12:19 PM Page 16 Appendix Predeveloped Schematic wwhm 8/12/2025 3:12:19 PM Page 17 Mitigated Schematic wwhm 8/12/2025 3:12:20 PM Page 18 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 wwhm.wdm MESSU 25 Prewwhm.MES 27 Prewwhm.L61 28 Prewwhm.L62 30 POCwwhm1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 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 # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 1 A/B, 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 *** 1 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 ********* 1 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO wwhm 8/12/2025 3:12:20 PM Page 19 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 1 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 1 0 5 2 400 0.05 0.3 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 1 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 1 0.2 0.5 0.35 0 0.7 0.7 END PWAT-PARM4 PWAT-STATE1 <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 1 0 0 0 0 3 1 0 END PWAT-STATE1 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 IWAT SLD IWG IQAL *** END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT 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 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATE1 wwhm 8/12/2025 3:12:20 PM Page 20 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 1 0.484 COPY 501 12 PERLND 1 0.484 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 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 *** 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 PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 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 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC wwhm 8/12/2025 3:12:20 PM Page 21 WDM 1 EVAP ENGL 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*** 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 INPUT 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 wwhm 8/12/2025 3:12:20 PM Page 22 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 wwhm.wdm MESSU 25 Mitwwhm.MES 27 Mitwwhm.L61 28 Mitwwhm.L62 30 POCwwhm1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 7 IMPLND 1 IMPLND 4 IMPLND 5 IMPLND 8 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 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 # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 7 A/B, 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 *** 7 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR wwhm 8/12/2025 3:12:20 PM Page 23 # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 7 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 *** 7 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 7 0 5 0.8 400 0.05 0.3 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 7 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 7 0.1 0.5 0.25 0 0.7 0.25 END PWAT-PARM4 PWAT-STATE1 <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 7 0 0 0 0 3 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 1 ROADS/FLAT 1 1 1 27 0 4 ROOF TOPS/FLAT 1 1 1 27 0 5 DRIVEWAYS/FLAT 1 1 1 27 0 8 SIDEWALKS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 4 0 0 1 0 0 0 5 0 0 1 0 0 0 8 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 4 1 9 4 0 0 4 0 0 0 1 9 5 0 0 4 0 0 0 1 9 8 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 *** 1 0 0 0 0 0 wwhm 8/12/2025 3:12:20 PM Page 24 4 0 0 0 0 0 5 0 0 0 0 0 8 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 4 400 0.01 0.1 0.1 5 400 0.01 0.1 0.1 8 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 4 0 0 5 0 0 8 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 4 0 0 5 0 0 8 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 7 0.354 COPY 501 12 PERLND 7 0.354 COPY 501 13 IMPLND 1 0.071 COPY 501 15 IMPLND 4 0.003 COPY 501 15 IMPLND 5 0.021 COPY 501 15 IMPLND 8 0.035 COPY 501 15 ******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 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 *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** wwhm 8/12/2025 3:12:20 PM Page 25 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 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 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 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*** 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 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 END MASS-LINK END RUN wwhm 8/12/2025 3:12:20 PM Page 26 Predeveloped HSPF Message File wwhm 8/12/2025 3:12:20 PM Page 27 Mitigated HSPF Message File wwhm 8/12/2025 3:12:20 PM Page 28 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. 2005-2025; 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 Page | 57 © Site Design, LLC Saleh Foundation Center Wetland Hydroperiod Analysis WWHM2012 PROJECT REPORT wwhm 8/12/2025 12:35:56 PM Page 2 General Model Information WWHM2012 Project Name:wwhm Site Name:Saleh Foundation Community Center Site Address:4018 Jones Ave NE City:Renton, WA 98056 Report Date:8/12/2025 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2023/03/31 Version:4.2.19 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year wwhm 8/12/2025 12:35:56 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre A B, Forest, Mod 0.533 Pervious Total 0.533 Impervious Land Use acre Impervious Total 0 Basin Total 0.533 wwhm 8/12/2025 12:35:56 PM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROOF TOPS FLAT 0.0028 Impervious Total 0.0028 Basin Total 0.0028 wwhm 8/12/2025 12:35:56 PM Page 5 Routing Elements Predeveloped Routing wwhm 8/12/2025 12:35:56 PM Page 6 Mitigated Routing wwhm 8/12/2025 12:35:56 PM Page 7 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.533 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.0028 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000462 5 year 0.000763 10 year 0.00103 25 year 0.001463 50 year 0.001866 100 year 0.002349 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.001068 5 year 0.001348 10 year 0.001539 25 year 0.001787 50 year 0.001976 100 year 0.00217 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.001 1950 0.001 0.001 1951 0.001 0.001 1952 0.000 0.001 1953 0.000 0.001 1954 0.000 0.001 1955 0.000 0.001 1956 0.000 0.001 1957 0.000 0.001 1958 0.000 0.001 wwhm 8/12/2025 12:36:21 PM Page 8 1959 0.000 0.001 1960 0.000 0.001 1961 0.000 0.001 1962 0.000 0.001 1963 0.000 0.001 1964 0.000 0.001 1965 0.000 0.001 1966 0.000 0.001 1967 0.000 0.001 1968 0.000 0.001 1969 0.000 0.001 1970 0.000 0.001 1971 0.000 0.001 1972 0.003 0.001 1973 0.000 0.001 1974 0.000 0.001 1975 0.000 0.001 1976 0.000 0.001 1977 0.000 0.001 1978 0.000 0.001 1979 0.000 0.002 1980 0.000 0.001 1981 0.000 0.001 1982 0.000 0.002 1983 0.000 0.001 1984 0.000 0.001 1985 0.000 0.001 1986 0.000 0.001 1987 0.000 0.001 1988 0.000 0.001 1989 0.000 0.001 1990 0.000 0.002 1991 0.001 0.002 1992 0.000 0.001 1993 0.000 0.001 1994 0.000 0.001 1995 0.000 0.001 1996 0.004 0.001 1997 0.000 0.001 1998 0.000 0.001 1999 0.001 0.002 2000 0.000 0.001 2001 0.000 0.001 2002 0.000 0.001 2003 0.000 0.001 2004 0.000 0.002 2005 0.000 0.001 2006 0.000 0.001 2007 0.006 0.002 2008 0.000 0.001 2009 0.000 0.001 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0062 0.0021 2 0.0041 0.0020 3 0.0031 0.0019 wwhm 8/12/2025 12:36:21 PM Page 9 4 0.0011 0.0019 5 0.0011 0.0016 6 0.0010 0.0015 7 0.0010 0.0015 8 0.0005 0.0015 9 0.0004 0.0015 10 0.0004 0.0015 11 0.0004 0.0015 12 0.0004 0.0014 13 0.0004 0.0014 14 0.0004 0.0014 15 0.0004 0.0014 16 0.0004 0.0013 17 0.0004 0.0013 18 0.0004 0.0012 19 0.0004 0.0012 20 0.0004 0.0012 21 0.0004 0.0012 22 0.0004 0.0011 23 0.0004 0.0011 24 0.0004 0.0011 25 0.0004 0.0011 26 0.0004 0.0011 27 0.0004 0.0011 28 0.0004 0.0011 29 0.0004 0.0011 30 0.0004 0.0011 31 0.0004 0.0011 32 0.0004 0.0010 33 0.0004 0.0010 34 0.0004 0.0010 35 0.0004 0.0010 36 0.0004 0.0010 37 0.0004 0.0010 38 0.0004 0.0010 39 0.0004 0.0010 40 0.0004 0.0009 41 0.0004 0.0009 42 0.0004 0.0009 43 0.0004 0.0009 44 0.0004 0.0009 45 0.0004 0.0009 46 0.0004 0.0009 47 0.0004 0.0009 48 0.0004 0.0009 49 0.0004 0.0009 50 0.0004 0.0009 51 0.0004 0.0008 52 0.0004 0.0008 53 0.0004 0.0008 54 0.0004 0.0008 55 0.0004 0.0008 56 0.0004 0.0008 57 0.0004 0.0008 58 0.0004 0.0008 59 0.0004 0.0008 60 0.0003 0.0007 61 0.0003 0.0007 wwhm 8/12/2025 12:36:21 PM Page 10 wwhm 8/12/2025 12:36:21 PM Page 11 Duration Flows The Duration Matching Failed Flow(cfs)Predev Mit Percentage Pass/Fail 0.0002 2920 17973 615 Fail 0.0002 2502 15590 623 Fail 0.0003 2124 13458 633 Fail 0.0003 1807 11828 654 Fail 0.0003 1507 10209 677 Fail 0.0003 1305 8981 688 Fail 0.0003 1086 7877 725 Fail 0.0003 856 6889 804 Fail 0.0004 629 6030 958 Fail 0.0004 480 5354 1115 Fail 0.0004 330 4688 1420 Fail 0.0004 197 4164 2113 Fail 0.0004 42 3657 8707 Fail 0.0004 35 3300 9428 Fail 0.0005 33 2943 8918 Fail 0.0005 31 2616 8438 Fail 0.0005 30 2357 7856 Fail 0.0005 29 2117 7300 Fail 0.0005 29 1877 6472 Fail 0.0005 29 1692 5834 Fail 0.0006 28 1492 5328 Fail 0.0006 28 1346 4807 Fail 0.0006 27 1209 4477 Fail 0.0006 27 1073 3974 Fail 0.0006 27 975 3611 Fail 0.0006 27 883 3270 Fail 0.0007 26 813 3126 Fail 0.0007 25 741 2964 Fail 0.0007 25 669 2676 Fail 0.0007 24 607 2529 Fail 0.0007 23 562 2443 Fail 0.0007 23 518 2252 Fail 0.0008 23 468 2034 Fail 0.0008 22 428 1945 Fail 0.0008 22 398 1809 Fail 0.0008 21 366 1742 Fail 0.0008 21 339 1614 Fail 0.0008 21 312 1485 Fail 0.0009 21 288 1371 Fail 0.0009 21 265 1261 Fail 0.0009 20 246 1230 Fail 0.0009 19 225 1184 Fail 0.0009 19 209 1100 Fail 0.0009 18 196 1088 Fail 0.0010 18 181 1005 Fail 0.0010 16 171 1068 Fail 0.0010 16 153 956 Fail 0.0010 16 144 900 Fail 0.0010 16 136 850 Fail 0.0010 15 124 826 Fail 0.0011 15 114 760 Fail 0.0011 15 107 713 Fail 0.0011 15 105 700 Fail 0.0011 15 99 660 Fail wwhm 8/12/2025 12:36:21 PM Page 12 0.0011 14 90 642 Fail 0.0011 13 84 646 Fail 0.0012 13 79 607 Fail 0.0012 13 72 553 Fail 0.0012 13 66 507 Fail 0.0012 13 63 484 Fail 0.0012 13 62 476 Fail 0.0012 12 57 475 Fail 0.0013 11 54 490 Fail 0.0013 11 53 481 Fail 0.0013 11 50 454 Fail 0.0013 11 48 436 Fail 0.0013 11 45 409 Fail 0.0013 10 40 400 Fail 0.0014 10 36 360 Fail 0.0014 10 33 330 Fail 0.0014 9 29 322 Fail 0.0014 9 28 311 Fail 0.0014 9 25 277 Fail 0.0014 9 22 244 Fail 0.0015 9 21 233 Fail 0.0015 8 19 237 Fail 0.0015 8 16 200 Fail 0.0015 8 12 150 Fail 0.0015 8 12 150 Fail 0.0015 8 9 112 Fail 0.0016 8 9 112 Fail 0.0016 8 9 112 Fail 0.0016 8 8 100 Pass 0.0016 8 8 100 Pass 0.0016 8 8 100 Pass 0.0016 8 8 100 Pass 0.0017 8 8 100 Pass 0.0017 8 8 100 Pass 0.0017 8 7 87 Pass 0.0017 8 7 87 Pass 0.0017 8 7 87 Pass 0.0017 8 7 87 Pass 0.0018 8 7 87 Pass 0.0018 8 6 75 Pass 0.0018 8 6 75 Pass 0.0018 8 6 75 Pass 0.0018 8 6 75 Pass 0.0018 8 6 75 Pass 0.0018 8 6 75 Pass 0.0019 8 5 62 Pass The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 50% of the flows for the range of the duration analysis. wwhm 8/12/2025 12:36:21 PM Page 13 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0.0664 acre-feet On-line facility target flow:0.0878 cfs. Adjusted for 15 min:0.0878 cfs. Off-line facility target flow:0.0496 cfs. Adjusted for 15 min:0.0496 cfs. wwhm 8/12/2025 12:36:21 PM Page 14 LID Report wwhm 8/12/2025 12:36:28 PM Page 15 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. wwhm 8/12/2025 12:36:28 PM Page 16 Appendix Predeveloped Schematic wwhm 8/12/2025 12:36:29 PM Page 17 Mitigated Schematic wwhm 8/12/2025 12:36:29 PM Page 18 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 wwhm.wdm MESSU 25 Prewwhm.MES 27 Prewwhm.L61 28 Prewwhm.L62 30 POCwwhm1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 2 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 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 # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 2 A/B, Forest, Mod 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 *** 2 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 ********* 2 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO wwhm 8/12/2025 12:36:29 PM Page 19 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 2 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 2 0 5 2 400 0.1 0.3 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 2 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 2 0.2 0.5 0.35 0 0.7 0.7 END PWAT-PARM4 PWAT-STATE1 <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 2 0 0 0 0 3 1 0 END PWAT-STATE1 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 IWAT SLD IWG IQAL *** END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT 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 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATE1 wwhm 8/12/2025 12:36:29 PM Page 20 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 2 0.533 COPY 501 12 PERLND 2 0.533 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 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 *** 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 PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 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 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC wwhm 8/12/2025 12:36:29 PM Page 21 WDM 1 EVAP ENGL 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*** 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 INPUT 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 wwhm 8/12/2025 12:36:29 PM Page 22 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 wwhm.wdm MESSU 25 Mitwwhm.MES 27 Mitwwhm.L61 28 Mitwwhm.L62 30 POCwwhm1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 IMPLND 4 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 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 # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* END PRINT-INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** wwhm 8/12/2025 12:36:29 PM Page 23 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** END PWAT-PARM4 PWAT-STATE1 <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 END PWAT-STATE1 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 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 4 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 4 0 0 4 0 0 4 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 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 4 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 4 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 4 0 0 END IWAT-STATE1 END IMPLND wwhm 8/12/2025 12:36:29 PM Page 24 SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** IMPLND 4 0.0028 COPY 501 15 ******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 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 *** 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 PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 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 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP wwhm 8/12/2025 12:36:29 PM Page 25 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 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 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 END MASS-LINK END RUN wwhm 8/12/2025 12:36:29 PM Page 26 Predeveloped HSPF Message File wwhm 8/12/2025 12:36:29 PM Page 27 Mitigated HSPF Message File wwhm 8/12/2025 12:36:29 PM Page 28 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. 2005-2025; 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 Page | 58 © Site Design, LLC Saleh Foundation Center SECTION IV CONVEYANCE SYSTEM ANALYSIS AND DESIGN Per C.R. #4 of the RSWDM, the conveyance system must be analyzed and designed for existing tributary and developed onsite runoff from the proposed project. Pipe systems shall be designed to convey the 100-year design storm. Developed surface runoff from the developed areas has been designed to drain to proposed catch basins to be located in Jones Ave NE. Developed roof runoff from the new building will be collected and conveyed to gravel filled full infiltration trenches. The proposed 6-inch PVC on-Site conveyance system have been analyzed using the Manning’s Equation. The conveyance system consisting primarily of pipes and catch basins has been designed for the Project. Pipes are typically 6-inch and 12-inch diameters PVC, LCPE material. The 6-inch pipes will have a minimum slope of 2.00%. The peak flow rate calculated for the Site is 0.1413 cfs theoretically occurring during the 100-year, 15-minute storm event. Per the following calculations, the most shallow-sloped pipe proposed in the conveyance system is capable of conveying a quantity greater than this flow. Page | 59 © Site Design, LLC Saleh Foundation Center DEVELOPED 15-MINUTE TIME STEP MODELING INPUT: Page | 60 © Site Design, LLC Saleh Foundation Center Flow Frequency Return Periods for Mitigated. POC #1 Haestad Methods FlowMaster I version 3.43 Circular Channel: Manning's Equation 6” Diameter Conveyance Solve For......Full Flow Capacity Diameter....................0.50 ft……………...Velocity………………….4.38 fps Slope.........................0.020 ft/ft…………..Flow Area……………….0.20 sf Manning's n………….0.012………………Critical Slope……………0.0175 ft/ft Discharge………........0.86 cfs……………Critical Depth……………0.45 ft Depth…………………0.05 ft………………Percent Full……………..100.00 % …………………………………………….....Froude Number…………FULL ………………………………………………..Full Capacity……………0.86 cfs ………………………………………………..QMAX @.94D…………..0.92 cfs Page | 61 © Site Design, LLC Saleh Foundation Center SECTION V SPECIAL REPORTS AND STUDIES The following report and studies are or have been provided for this Project. 1. Geotechnical Report prepared by Cobalt Geosciences, dated October 11, 2023. 2. Wetland Assessment Report by Altmann Oliver Associates, LLC dated June 25, 2025. 3. Traffic Report by Wassim Kebab, PE dated June 30, 2025. 4. Arborist Report by Cascara Tree Consulting dated July 26, 2025. Page | 62 © Site Design, LLC Saleh Foundation Center SECTION VI OTHER PERMITS, VARIANCES AND ADJUSTMENTS The following permits, variances or adjustments have been required as part of this development, as of the date of this report: 1. Conditional Use Permit (CUM). 2. Construction Stormwater Permit from Department of Ecology . Page | 63 © Site Design, LLC Saleh Foundation Center SECTION VII CSWPPP ANALYSIS AND DESIGN ESC PLAN ANALYSIS AND DESIGN (PART A) The Erosion and Sedimentation Control Design meets the nine minimum requirements: 1. Clearing Limits – Areas to remain undisturbed shall be delineated with a high- visibility plastic fence prior to any site clearing or grading. 2. Cover Measures – Disturbed Site areas shall be covered with mulch and seeded, as appropriate, for temporary or permanent measures. 3. Perimeter protection – Perimeter protection shall consist of a silt fence down slope of any disturbed areas or stockpiles. 4. Traffic Area Stabilization – A stabilized construction entrance will be located at the point of ingress/egress. 5. Sediment Retention – Permanent stormwater vault will be utilized for construction stormwater. Due to the size of the project and the nature of the proposed improvements, any sediment laden water must be pumped to the stormwater conveyance system after being treated, if necessary. Baker Tank will be utilized if necessary. 6. Surface Water Control – If necessary, surface water control will be provided by interceptor swales. 7. Dewatering Control – Will be provided as needed. 8. Dust Control – Dust control shall be provided by spraying exposed soils with water until wet. This is required when exposed soils are dry to the point that wind transport is possible which would impact roadways, drainage ways, surface waters, or neighboring residences. CSWPP PLAN DESIGN (PART B) Construction activities that could contribute pollutants to surface and storm water include the following, with applicable BMP’s listed for each item: 1. Storage and use of chemicals: Utilize source control, and soil erosion and sedimentation control practices, such as using only recommended amounts of chemical materials applied in the proper manner; neutralizing concrete wash water, and disposing of excess concrete material only in areas prepared for concrete placement, or return to batch plant; disposing of wash-up waters from water-based paints in sanitary sewer; disposing of wastes from oil-based paints, solvents, thinners, and mineral spirits only through a licensed waste management firm, or treatment, storage, and disposal (TSD) facility. 2. Material delivery and storage: Locate temporary storage areas away from vehicular traffic, near the construction entrance, and away from storm drains. Material Safety Data Sheets (MSDS) should be supplied for all materials stored, and chemicals kept in their original labeled containers. Maintenance, fueling, and repair of heavy Page | 64 © Site Design, LLC Saleh Foundation Center equipment and vehicles shall be conducted using spill prevention and control measures. Contaminated surfaces shall be cleaned immediately following any spill incident. Provide cover, containment, and protection from vandalism for all chemicals, liquid pr oducts, petroleum products, and other potentially hazardous materials. 3. Sawcutting: Slurry and cuttings shall be vacuumed during the activity to prevent migration offsite and must not remain on permanent concrete or asphalt paving overnight. Collected slurry and cuttings shall be disposed of in a manner that does not violat e ground water or surface water quality standards. A complete Construction Stormwater Pollution Prevention Plan (CSWPPP) will be provided at final engineering. Page | 65 © Site Design, LLC Saleh Foundation Center SECTION VIII BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT BOND QUANTITY WORKSHEET To be provided at the final engineering. DECLARATION OF COVENANT A recorded covenant will be provided prior to granting the certificate of occupancy. Page | 66 © Site Design, LLC Saleh Foundation Center SECTION IX OPERATIONS AND MAINTENANCE MANUAL Section 1 – Project Description This project will create a new 5-story building with ground level parking under the building including access driveway to parking, utilities, stormwater facilities, and associated grading and landscaping. Frontage improvements will be created for Jones Ave NE consisting of 28 feet of pavement width, concrete curb -gutter, landscape buffers and concrete sidewalk. The property is located at 4108 and 41XX, Renton, WA 98056, in the City of Renton, with parcel numbers 3345700080 and 3345700085. The existing Site area is 52,341 s.f. (1.202 ac.). The buildable area is 14,876 s.f. (0.342 ac.) after excluding wetland buffers and structure setback areas has a zoning classification of Commercial Arterial (CA) (CA) and Urban Design District D overlay. The comprehensive plan land use designation is mixed-use (CMU). The project will utilize stormwater BMPs to mitigate runoff generated by new surfaces. Developed roof runoff from the new building will be collected and conveyed to gravel filled full infiltration trenches. The surface runoff from onsite driveway and frontage improvements in Jones Ave NE will be collected and conveyed to the existing downstream storm drainage systems. The project meets the 0.15 cfs exemption. The project will add 4,033 s.f. of effective PGIS from Jones Ave NE frontage improvements. Cleared and landscaped areas will receive amended soil. The project will meet flow control standards and water quality standards. Section 2 – Maintenance Importance and Intent The importance of maintenance for the proper functioning of stormwater control facilities cannot be over-emphasized. A substantial portion of failures (clogging of filters, resuspension of sediments, loss of storage capacity, etc.) are due to inadequate maintenance. Stormwater BMP maintenance is essential to ensure that BMPs function as intended throughout their full life cycle. The fundamental goals of maintenance activities are to ensure the entire flow regime and treatment train designed for this site continue to fully function. These may include: • Maintain designed stormwater infiltration capacity. • Maintain designed stormwater detention/retention volume . • Maintain ability of storm facility to attenuate flow rates . • Maintain ability to safely convey design stormwater flows . • Maintain ability to treat stormwater runoff quality . • Preserve soil and plant health, as well as stormwater flow contact with plant and soil systems. • Clearly identify systems so they can be protected . • Keep maintenance costs low. • Preventing large-scale or expensive stormwater system failures. • Prevent water quality violations or damage to downstream properties . The intent of this section and manual is to pass on to the responsible party(s) all the information critical to understand the design of the system, risks and considerations for Page | 67 © Site Design, LLC Saleh Foundation Center proper use, suggestions for maintenance frequencies, and cost so that realistic budgets can be established. Section 3 – Responsible Parties The property owners are responsible for the maintenance and operation of private stormwater facilities and associated conveyance systems constructed for this project. The City of Renton will be responsible for the maintenance and operation of Jones Ave NE improvements. Section 4 – Facilities Requiring Maintenance Structures and BMPs requiring maintenance for the project: infiltration trenches, sediment control structures, catch basins, pipes and landscaping. Section 5 – Maintenance Instructions The parties responsible for maintenance must review and apply the maintenance requirements contained herein. These maintenance instructions outline conditions for determining if maintenance actions are required, as identified through inspection. However, they are not intended to be measures of the facility's required condition at all times between inspections. Exceedance of these conditions at any time between inspections or maintenance activity does not automatically constitute a violation of these standards. However, based upon inspection observations, the inspection and maintenance presented in the checklists shall be adjusted to minimize the length of time that a facility is in a condition that requires a maintenance action. For facilities not owned and maintained by the City, a log of maintenance activity that indicates what actions were taken must be kept on site and be available for inspection by the City. The Type 1 catch basins have a one -foot deep sump, and the Type 2 catch basins have a two-foot deep sump for sediment accumulation. These sumps should be periodically checked, and the sediment removed when accumulated to more than 1/3 of the depth from the bottom of the basin to the invert of the lowest pipe into or out of the basin. Grates should be cleaned when trash or debris of more than ½ cubic foot is located immediately in front of the basin opening, or is blocking capacity of the basin by more than 10%. Conveyance pipes should be periodically checked and cleaned when more than 20% of the pipe diameter is obstructed by accumulated sediment or debris. Floating debris and accumulated petroleum products should be removed as needed, but at least annually. Perform inspections of all components quarterly during the first year of operation, then annually thereafter. For more detailed maintenance instructions, refer to the standards contained at the end of this section. The following excerpts from the 2022 RSWDM describe maintenance instructions for all applicable storm components, BMPs and facilities found on site. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-4 NO. 2 – INFILTRATION FACILITIES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Infiltration Pond, Top or Side Slopes of Dam, Berm or Embankment Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of dams, berms or slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat to dam, berm, or embankment integrity or not interfering with access or maintenance, they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. Settlement Any part of a dam, berm or embankment that has settled 4 inches lower than the design elevation. Top or side slope restored to design dimensions. If settlement is significant, a licensed civil engineer should be consulted to determine the cause of the settlement. Infiltration Pond, Tank, Vault, Trench, or Small Basin Storage Area Sediment accumulation If two inches or more sediment is present or a percolation test indicates facility is working at or less than 90% of design. Facility infiltrates as designed. Liner damaged If applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Infiltration Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of shape Any part of tank/pipe is bent out of shape more than 10% of its design shape. Tank repaired or replaced to design. Gaps between sections, damaged joints or cracks or tears in wall A gap wider than ½-inch at the joint of any tank sections or any evidence of soil particles entering the tank at a joint or through a wall. No water or soil entering tank through joints or walls. Infiltration Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-5 NO. 2 – INFILTRATION FACILITIES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Inlet/Outlet Pipes Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can be opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. Infiltration Pond, Tank, Vault, Trench, or Small Basin Filter Bags Plugged filter bag (if applicable) Filter bag more than 1/ 2 full. Replace filter bag or redesign system. Infiltration Pond, Tank, Vault, Trench, or Small Basin Pre- settling Ponds and Vaults Sediment accumulation 6" or more of sediment has accumulated. Pre-settling occurs as designed Infiltration Pond, Rock Filter Plugged rock filter High water level on upstream side of filter remains for extended period of time or little or no water flows through filter during heavy rain storms. Rock filter replaced evaluate need for filter and remove if not necessary. Infiltration Pond Emergency Overflow Spillway Rock missing Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. Spillway restored to design standards. Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-10 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Structure Sediment accumulation Sediment exceeds 60% of the depth from the bottom of the catch basin to the invert of the lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Sump of catch basin contains no sediment. Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the catch basin opening or is blocking capacity of the catch basin by more than 10%. No Trash or debris blocking or potentially blocking entrance to catch basin. Trash or debris in the catch basin that exceeds 1/ 3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the catch basin. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within catch basin. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering catch basin through cracks, or maintenance person judges that catch basin is unsound. Catch basin is sealed and is structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. No cracks more than 1/ 4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Catch basin has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the catch basin at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-11 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Inlet/Outlet Pipe cont.) Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Metal Grates Catch Basins) Unsafe grate opening Grate with opening wider than 7/ 8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. Damaged or missing grate Grate missing or broken member(s) of the grate. Any open structure requires urgent maintenance. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-12 NO. 6 – CONVEYANCE PIPES AND DITCHES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Pipes Sediment & debris accumulation Accumulated sediment or debris that exceeds 20% of the diameter of the pipe. Water flows freely through pipes. Vegetation/root growth in pipe Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective coating or corrosion Protective coating is damaged; rust or corrosion is weakening the structural integrity of any part of pipe. Pipe repaired or replaced. Damaged pipes Any dent that decreases the cross section area of pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Pipe repaired or replaced. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet of ditch and slopes. Trash and debris cleared from ditches. Sediment accumulation Accumulated sediment that exceeds 20% of the design depth. Ditch cleaned/flushed of all sediment and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive vegetation growth Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion damage to slopes Any erosion observed on a ditch slope. Slopes are not eroding. Rock lining out of place or missing (If applicable) One layer or less of rock exists above native soil area 5 square feet or more, any exposed native soil. Replace rocks to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-13 NO. 7 – DEBRIS BARRIERS (E.G., TRASH RACKS) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED. Site Trash and debris Trash or debris plugging more than 20% of the area of the barrier. Barrier clear to receive capacity flow. Sediment accumulation Sediment accumulation of greater than 20% of the area of the barrier Barrier clear to receive capacity flow. Structure Cracked, broken, or loose pipe or structure Structure which bars attached to is damaged – pipe is loose or cracked or concrete structure is cracked, broken, or loose. Structure barrier attached to is sound. Bars Incorrect bar spacing Bar spacing exceeds 6 inches. Bars have at most 6 inches spacing. Damaged or missing bars Bars are bent out of shape more than 3 inches. Bars in place with no bends more than ¾ inch. Bars are missing or entire barrier missing. Bars in place according to design. Bars are loose and rust is causing 50% deterioration to any part of barrier. Repair or replace barrier to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-15 NO. 9 – FENCING MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Erosion or holes under fence Erosion or holes more than 4 inches high and 12-18 inches wide permitting access through an opening under a fence. No access under the fence. Wood Posts, Boards and Cross Members Missing or damaged parts Missing or broken boards, post out of plumb by more than 6 inches or cross members broken No gaps on fence due to missing or broken boards, post plumb to within 1½ inches, cross members sound. Weakened by rotting or insects Any part showing structural deterioration due to rotting or insect damage All parts of fence are structurally sound. Damaged or failed post foundation Concrete or metal attachments deteriorated or unable to support posts. Post foundation capable of supporting posts even in strong wind. Metal Posts, Rails and Fabric Damaged parts Post out of plumb more than 6 inches. Post plumb to within 1½ inches. Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. Any part of fence (including post, top rails, and fabric) more than 1 foot out of design alignment. Fence is aligned and meets design standards. Missing or loose tension wire. Tension wire in place and holding fabric. Deteriorated paint or protective coating Part or parts that have a rusting or scaling condition that has affected structural adequacy. Structurally adequate posts or parts with a uniform protective coating. Openings in fabric Openings in fabric are such that an 8-inch diameter ball could fit through. Fabric mesh openings within 50% of grid size. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-17 NO. 11 – GROUNDS (LANDSCAPING) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Trees and Shrubs Hazard tree identified Any tree or limb of a tree identified as having a potential to fall and cause property damage or threaten human life. A hazard tree identified by a qualified arborist must be removed as soon as possible. No hazard trees in facility. Damaged tree or shrub identified Limbs or parts of trees or shrubs that are split or broken which affect more than 25% of the total foliage of the tree or shrub. Trees and shrubs with less than 5% of total foliage with split or broken limbs. Trees or shrubs that have been blown down or knocked over. No blown down vegetation or knocked over vegetation. Trees or shrubs free of injury. Trees or shrubs which are not adequately supported or are leaning over, causing exposure of the roots. Tree or shrub in place and adequately supported; dead or diseased trees removed. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-33 NO. 22 – BAFFLE OIL/WATER SEPARATOR MAINTENANCE COMPONENT DEFECT CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash or debris which impairs the function of the facility. Trash and debris removed from facility. Contaminants and pollution Floating oil in excess of 1 inch in first chamber, any oil in other chambers or other contaminants of any type in any chamber. No contaminants present other than a surface oil film. Vault Treatment Area Sediment accumulation Sediment accumulates exceeds 6 inches in the vault. No sediment in the vault. Discharge water not clear Inspection of discharge water shows obvious signs of poor water quality- effluent discharge from vault shows thick visible sheen. Effluent discharge is clear. Trash or debris accumulation Any trash and debris accumulation in vault floatables and non-floatables). Vault is clear of trash and debris. Oil accumulation Oil accumulations that exceed 1 inch, at the surface of the water in the oil/water separator chamber. No visible oil depth on water. Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch or evidence of soil particles entering the structure through the cracks, or maintenance/inspection personnel determines that the vault is not structurally sound. Vault replaced or repaired to design specifications. Baffles damaged Baffles corroding, cracking, warping and/or showing signs of failure as determined by maintenance inspection personnel. Repair or replace baffles to specifications. Gravity Drain Inoperable valve Valve will not open and close. Valve opens and closes normally. Valve won’t seal Valve does not seal completely. Valve completely seals closed. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-34 NO. 22 – BAFFLE OIL/WATER SEPARATOR MAINTENANCE COMPONENT DEFECT CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Large Access Doors/Plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can be opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat and cover access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or cover/lid. Lifting rings sufficient to lift or remove cover/lid. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-37 NO. 24 – CATCH BASIN INSERT (NOT ALLOWED IN THE CITY FOR OIL CONTROL) APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-38 NO. 25 – DRYWELL BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Plugging, obstructions Any cause limiting flow into drywell. Drywell able to receive full flow prior to and during wet season. Site Trash and debris Trash or debris that could end up in the drywell is evident. No trash or debris that could get into the drywell can be found. Pipes Plugged inlet The entrance to the pipe is restricted due to sediment, trash, or debris. The entrance to the pipe is not restricted. Vegetation/root growth in pipes Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Plugged pipe Sediment or other material prevents free flow of water through the pipe. Water flows freely through pipes. Broken pipe or joint leaks Damage to the pipe or pipe joints allowing water to seep out. Pipe does not allow water to exit other than at the outlet. Structure Basin leaks Holes or breaks in the basin allow water to leave the basin at locations other than per design. Basin is sealed and allows water to exit only where designed. Filter Media Plugged filter media Filter media plugged. Flow through filter media is normal. NO. 26 – GRAVEL FILLED INFILTRATION TRENCH BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Blocking, obstructions Debris or trash limiting flow to infiltration trench. Infiltration trench able to receive full flow prior to and during wet season. Site Trash and debris Trash or debris that could end up in the infiltration trench is evident. No trash or debris that could get into the infiltration trench can be found. Pipes Plugged inlet The entrance to the pipe is restricted due to sediment, trash, or debris. The entrance to the pipe is not restricted. Vegetation/root growth in pipes Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Plugged pipes Sediment or other material prevents free flow of water through the pipe. Water flows freely through pipes. Broken pipe or joint leaks Damage to the pipe or pipe joints allowing water to seep out. Pipe does not allow water to exit other than at the outlet to the trench. Structure Flow not reaching trench Flows are not getting into the trench as designed. Water enters and exits trench as designed. Cleanout/inspection access does not allow cleaning or inspection of trench The cleanout/inspection access is not available. Cleanout/inspection access is available. Filter Media Plugged filter media Filter media plugged. Flow through filter media is normal. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-39 NO. 27 – GRAVEL FILLED DISPERSION TRENCH BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Blocking, obstructions Debris or trash limiting flow to dispersion trench or preventing spreader function. Dispersion trench able to receive full flow prior to and during wet season. Site Trash and debris Trash or debris that could end up in the dispersion trench is evident. No trash or debris that could get into the dispersion trench can be found. Pipes Plugged inlet The entrance to the pipe is restricted due to sediment, trash, or debris. The entrance to the pipe is not restricted. Vegetation/root growth in pipes Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Plugged pipe Sediment or other material prevents free flow of water through the pipe. Water flows freely through pipes. Broken pipe or joint leaks. Damage to the pipe or pipe joints allowing water to seep out. Pipe does not allow water to exit other than at the outlet to the trench. Broken or missing cleanout caps Cleanout caps are broken, missing, or buried. Cleanout caps are accessible and intact. Structure Flow not reaching trench Flows are not getting into the trench as designed. Water enters and exits trench as designed. Perforated pipe plugged Flow not able to enter or properly exit from perforated pipe. Water freely enters and exits perforated pipe. Flow not spreading evenly at outlet of trench Outlet flows channelizing or not spreading evenly from trench. Sheet flow occurs at the outlet of the trench. Cleanout/inspection access does not allow cleaning or inspection of perforated pipe The cleanout/inspection access is not available. Cleanout/inspection access is available. Filter Media Plugged filter media Filter media plugged. Flow through filter media is normal. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-40 NO. 28 – NATIVE VEGETATED SURFACE/NATIVE VEGETATED LANDSCAPE BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on the native vegetated surface/native vegetated landscape site. Native vegetated surface site free of any trash or debris. Vegetation Insufficient vegetation Less than two species each of native trees, shrubs, and groundcover occur in the design area. A minimum of two species each of native trees, shrubs, and groundcover is established and healthy. Poor vegetation coverage Less than 90% if the required vegetated area has healthy growth. A minimum of 90% of the required vegetated area has healthy growth. Undesirable vegetation present Weeds, blackberry, and other undesirable plants are invading more than 10% of vegetated area. Less than 10% undesirable vegetation occurs in the required native vegetated surface area. Vegetated Area Soil compaction Soil in the native vegetation area compacted. Less than 8% of native vegetation area is compacted. Insufficient vegetation Less than 3.5 square feet of native vegetation area for every 1 square foot of impervious surface. A minimum of 3.5 square feet of native vegetation area for every 1 square foot of impervious surface. Excess slope Slope of native vegetation area greater than 15%. Slope of native growth area does not exceed 15%. NO. 29 – PERFORATED PIPE CONNECTIONS BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Blocking, obstructions Debris or trash limiting flow into perforated pipe system or outfall of BMP is plugged or otherwise nonfunctioning. Outfall of BMP is receiving designed flows from perforated pipe connection. Inflow Inflow impeded Inflow into the perforated pipe is partially or fully blocked or altered to prevent flow from getting into the pipe. Inflow to the perforated pipe is unimpeded. Pipe Trench Area Surface compacted Ground surface over the perforated pipe trench is compacted or covered with impermeable material. Ground surface over the perforated pipe is not compacted and free of any impervious cover. Outflow Outflow impeded Outflow from the perforated pipe into the public drainage system is blocked. Outflow to the public drainage system is unimpeded. Outfall Area Erosion or landslides Existence of the perforated pipe is causing or exasperating erosion or landslides. Perforated pipe system is sealed off and an alternative BMP is implemented. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-47 NO. 38 – SOIL AMENDMENT BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Soil Media Unhealthy vegetation Vegetation not fully covering ground surface or vegetation health is poor. Yellowing: possible Nitrogen (N) deficiency. Poor growth: possible Phosphorous (P) deficiency. Poor flowering, spotting or curled leaves, or weak roots or stems: possible Potassium K) deficiency. Plants are healthy and appropriate for site conditions Inadequate soil nutrients and structure In the fall, return leaf fall and shredded woody materials from the landscape to the site when possible Soil providing plant nutrients and structure Excessive vegetation growth Grass becomes excessively tall (greater than 10 inches); nuisance weeds and other vegetation start to take over. Healthy turf- “grasscycle” (mulch-mow or leave the clippings) to build turf health Weeds Preventive maintenance Avoid use of pesticides (bug and weed killers), like “weed & feed,” which damage the soil Fertilizer needed Where fertilization is needed (mainly turf and annual flower beds), a moderate fertilization program should be used which relies on compost, natural fertilizers or slow-release synthetic balanced fertilizers Integrated Pest Management (IPM) protocols for fertilization followed Bare spots Bare spots on soil No bare spots, area covered with vegetation or mulch mixed into the underlying soil. Compaction Poor infiltration due to soil compaction To remediate compaction, aerate soil, till to at least 8-inch depth, or further amend soil with compost and re-till If areas are turf, aerate compacted areas and top dress them with 1/4 to 1/2 inch of compost to renovate them If drainage is still slow, consider investigating alternative causes (e.g., high wet season groundwater levels, low permeability soils) Also consider site use and protection from compacting activities No soil compaction Poor infiltration Soils become waterlogged, do not appear to be infiltrating. Facility infiltrating properly Erosion/Scouring Erosion Areas of potential erosion are visible Causes of erosion (e.g., concentrate flow entering area, channelization of runoff) identified and damaged area stabilized regrade, rock, vegetation, erosion control matting).For deep channels or cuts (over 3 inches in ponding depth), temporary erosion control measures in place until permanent repairs can be made Grass/Vegetation Unhealthy vegetation Less than 75% of planted vegetation is healthy with a generally good appearance. Healthy vegetation. Unhealthy plants removed/replaced. Appropriate vegetation planted in terms of exposure, soil and soil moisture. Noxious Weeds Noxious weeds Listed noxious vegetation is present (refer to current County noxious weed list). No noxious weeds present. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-48 NO. 39 – RETAINED TREES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Tree Dead or declining Dead, damaged, or declining Tree replaced per planting plan or acceptable substitute NO. 40 – FILTERRA SYSTEM MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED In addition to the specific maintenance criteria provided below, all manufacturer’s requirements shall be followed. Facility – General Requirements Life cycle Once per year, except mulch and trash removal twice per year Facility is re-inspected and any needed maintenance performed Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries, or paint Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet Excessive sediment or trash accumulation Accumulated sediments or trash impair free flow of water into system Inlet should be free of obstructions allowing free distributed flow of water into system Mulch Cover Trash and floatable debris accumulation Excessive trash and/or debris accumulation Minimal trash or other debris on mulch cover. Mulch cover raked level. Ponding” of water on mulch cover Ponding” in unit could be indicative of clogging due to excessive fine sediment accumulation or spill of petroleum oils Stormwater should drain freely and evenly through mulch cover Proprietary Filter Media/ Vegetation Substrate Ponding” of water on mulch cover after mulch cover has been maintained Excessive fine sediment passes the mulch cover and clogs the filter media/vegetative substrate Stormwater should drain freely and evenly through mulch cover. Replace substrate and vegetation when needed Vegetation Plants not growing or in poor condition Soil/mulch too wet, evidence of spill, incorrect plant selection, pest infestation, and/or vandalism to plants Plants should be healthy and pest free Media/mulch too dry Irrigation is required Plants absent Plants absent Appropriate plants are present Excessive plant growth Excessive plant growth inhibits facility function or becomes a hazard for pedestrian and vehicular circulation and safety Pruning and/or thinning vegetation maintains proper plant density. Appropriate plants are present. Structure Structure has visible cracks Cracks wider than ½ inch Evidence of soil particles entering the structure through the cracks Structure is sealed and structurally sound APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-48 NO. 39 – RETAINED TREES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Tree Dead or declining Dead, damaged, or declining Tree replaced per planting plan or acceptable substitute NO. 40 – FILTERRA SYSTEM MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED In addition to the specific maintenance criteria provided below, all manufacturer’s requirements shall be followed. Facility – General Requirements Life cycle Once per year, except mulch and trash removal twice per year Facility is re-inspected and any needed maintenance performed Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries, or paint Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet Excessive sediment or trash accumulation Accumulated sediments or trash impair free flow of water into system Inlet should be free of obstructions allowing free distributed flow of water into system Mulch Cover Trash and floatable debris accumulation Excessive trash and/or debris accumulation Minimal trash or other debris on mulch cover. Mulch cover raked level. Ponding” of water on mulch cover Ponding” in unit could be indicative of clogging due to excessive fine sediment accumulation or spill of petroleum oils Stormwater should drain freely and evenly through mulch cover Proprietary Filter Media/ Vegetation Substrate Ponding” of water on mulch cover after mulch cover has been maintained Excessive fine sediment passes the mulch cover and clogs the filter media/vegetative substrate Stormwater should drain freely and evenly through mulch cover. Replace substrate and vegetation when needed Vegetation Plants not growing or in poor condition Soil/mulch too wet, evidence of spill, incorrect plant selection, pest infestation, and/or vandalism to plants Plants should be healthy and pest free Media/mulch too dry Irrigation is required Plants absent Plants absent Appropriate plants are present Excessive plant growth Excessive plant growth inhibits facility function or becomes a hazard for pedestrian and vehicular circulation and safety Pruning and/or thinning vegetation maintains proper plant density. Appropriate plants are present. Structure Structure has visible cracks Cracks wider than ½ inch Evidence of soil particles entering the structure through the cracks Structure is sealed and structurally sound