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TECHNICAL INFORMATION REPORT FOR Parking Lot Upgrades at 600 SW 10th Street Renton, WA 98057 October 31, 2023 PREPARED FOR: TESLA 600 SW 10TH STREET RENTON, WA, 98057 PREPARED BY: KIMLEY-HORN 1201 3RD AVENUE, SUITE 2800 SEATTLE, WA 98101 OFFICE: (206) 607-2700 KHA PROJECT #: 194612001 ©Kimley-Horn and Associates, Inc., 2023 10/31/20 2 3 Exhibit 10 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D (This sheet was intentionally left blank) DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Disclosure Statement: This document, together with the concepts and designs presented herein, as an instrument of service, is intended only for the specific purpose and client for which it was prepared. Reuse of and improper reliance on this document without written authorization and adaptation by Kimley-Horn and Associates, Inc. shall be without liability to Kimley-Horn and Associates, Inc. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page i Table of Contents TECHNICAL INFORMATION REPORT WORKSHEET ........................................................................... iv SECTION A – PROJECT OVERVIEW ..................................................................................................... 1 A.1 SITE LOCATION ...................................................................................................................... 1 A.2 EXISTING SITE CONDITIONS ................................................................................................. 1 A.3 EXISTING ON-SITE STORMWATER SYSTEMS ..................................................................... 1 A.4 ADJACENT PROPERTIES ....................................................................................................... 1 A.5 PROJECT IMPACT ON ADJACENT AREAS ............................................................................ 1 A.6 PROPOSED SITE CONDITIONS ............................................................................................. 2 A.7 REVISIONS TO PRELIMINARY STORMWATER REPORT ...................................................... 2 SECTION B – CORE REQUIREMENTS .................................................................................................. 2 B.1 APPLICABLE CORE REQUIREMENTS ......................................................................................... 2 TABLE 1 – LAND DISTURBING ACTIVITY ....................................................................................... 2 CR#1: Discharge at the Natural Location .......................................................................................... 2 CR#2: Offsite Analysis ...................................................................................................................... 3 CR#3: Flow Control Facilities ............................................................................................................ 3 CR#4: Conveyance System .............................................................................................................. 3 CR#5: Construction Stormwater Pollution Prevention (CSWPP) ........................................................ 3 CR#6: Maintenance and Operations ................................................................................................. 3 CR#7: Financial Guarantees and Liability.......................................................................................... 4 CR#8: Water Quality Facilities .......................................................................................................... 4 CR#9: On-Site BMPs ........................................................................................................................ 4 B.2 APPLICABLE SPECIAL REQUIREMENTS .................................................................................... 4 SR#1: Other Adopted Area-Specific Requirements ........................................................................... 4 SR#2: Flood Hazard Area Delineation............................................................................................... 4 SR#3: Flood Protection Facilities ...................................................................................................... 4 SR#4: Source Controls ..................................................................................................................... 4 SR#5: Oil Control .............................................................................................................................. 5 SR#6: Aquifer Protection Area .......................................................................................................... 5 SECTION C – PRELIMINARY SOILS EVALUATION ............................................................................... 5 SECTION D – OFFSITE ANALYSIS (CR#2) ............................................................................................ 5 Figure 1: Catch basin #1 along north side of SW 10th Street at the upstream end of the downstream storm system .................................................................................................................................... 6 Figure 2: Catch basin #2 along south side of SW 10th Street at the upstream end of the downstream storm system .................................................................................................................................... 6 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page ii Figure 3: Catch basin #3 along south side of SW 10th Street ............................................................ 7 Figure 4: Catch basin #4 along south side of SW 10th Street ............................................................ 7 Figure 5: Catch basin #5 along the curb at the NE corner of the intersection of SW 10th Street and Powell Avenue SW ........................................................................................................................... 8 Figure 6: Catch basin #6 along the curb at the SE corner of the intersection of SW 10th Street and Powell Avenue SW ........................................................................................................................... 8 Figure 7: Catch basin #7 along the west side of Powell Ave SW near the intersection of Powell Avenue SW and SW 10th Street ....................................................................................................... 9 Figure 8: Catch basin #8 along the west side of Powell Ave SW near the intersection of Powell Avenue SW and SW 10th Street ....................................................................................................... 9 Figure 9: Pipe daylight into ditch #1, with headwall slightly visible behind fallen tree ........................ 10 Figure 10: Ditch #1 as seen from the west looking east ................................................................... 10 Figure 11: Culvert #1 daylight from the east looking west ................................................................ 11 Figure 12: Culvert #1 daylight from the west looking east ................................................................ 11 Figure 13: Ditch #2 from the east looking west ................................................................................ 12 Figure 14: Culvert #2 daylight from the east looking west, with headwall partially visible behind brush ....................................................................................................................................................... 12 SECTION E – FLOW CONTROL FACILITIES (CR#3) ........................................................................... 13 SECTION F – CONVEYANCE SYSTEM (CR#4) ................................................................................... 13 SECTION G – WATER QUALITY FACILITIES (CR#8) ........................................................................... 14 Figure 15 – Water quality flow rate .................................................................................................. 15 SECTION H – ON-SITE BMPS (CR#9) .................................................................................................. 15 SECTION I – OTHER PERMITS ............................................................................................................ 17 SECTION J – OPERATIONS AND MAINTENANCE MANUAL (CR#6) ................................................... 17 SECTION M – APPENDICES ................................................................................................................ 18 APPENDIX A: MAPS ......................................................................................................................... 18 1. VICINITY MAP ....................................................................................................................... 18 2. FLOOD INSURANCE RATE MAP .......................................................................................... 19 3. PRE-DEVELOPMENT DRAINAGE AREA MAP ...................................................................... 20 4. POST-DEVELOPMENT DRAINAGE AREA MAP ................................................................... 21 5. PROPOSED DRAINAGE PLAN ............................................................................................. 22 6. AQUIFER PROTECTION AREA MAP .................................................................................... 23 7. DOWNSTREAM ANALYSIS STUDY AREA MAP ................................................................... 24 APPENDIX B: CALCULATIONS ......................................................................................................... 25 1. FLOW CONTROL CALCULATIONS ....................................................................................... 25 2. CONVEYANCE SYSTEM CALCULATIONS ........................................................................... 26 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page iii APPENDIX C: ADDITIONAL PLANS AND REPORTS ........................................................................ 28 1. GEOTECHNICAL ENGINEERING REPORT (FOR REFERENCE ONLY) ............................... 28 2. NRCS WEB SOIL SURVEY ................................................................................................... 29 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page iv TECHNICAL INFORMATION REPORT WORKSHEET DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D CITY OF RENTON SURFACE WATER DESIGN MANUAL 2022 City of Renton Surface Water Design Manual 6/22/2022 8-A-1 REFERENCE 8-A TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner _____________________________ Phone ___________________________________ Address __________________________________ _________________________________________ Project Engineer ___________________________ Company _________________________________ Phone ___________________________________ Project Name __________________________ CED Permit # ________________________ Location Township ________________ Range __________________ Section _________________ Site Address __________________________ _____________________________________ Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS Land Use (e.g., Subdivision / Short Subd.) Building (e.g., M/F / Commercial / SFR) Grading Right-of-Way Use Other _______________________ DFW HPA COE 404 DOE Dam Safety FEMA Floodplain COE Wetlands Other ________ Shoreline Management Structural Rockery/Vault/_____ ESA Section 7 Part 5 PLAN AND REPORT INFORMATION Technical Information Report Site Improvement Plan (Engr. Plans) Type of Drainage Review (check one): Date (include revision dates): Date of Final: Full Targeted Simplified Large Project Directed __________________ __________________ __________________ Plan Type (check one): Date (include revision dates): Date of Final: Full Modified Simplified __________________ __________________ __________________ None Renton, WA 98057 600 SW 10th Street 23 19 & 24 04 & 05 Parking Lot Upgrades 206-745-9976 Kimley-Horn Andrew Delia, P.E. Renton, WA 98057 600 SW 10th Street 415-805-6116 Tesla DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 6/22/2022 2022 City of Renton Surface Water Design Manual 8-A-2 Part 6 SWDM ADJUSTMENT APPROVALS Type (circle one): Standard / Blanket Description: (include conditions in TIR Section 2) ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ Approved Adjustment No. ______________________ Date of Approval: _______________________ Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: _______________________ Completion Date: _______________________ Describe: _________________________________ _________________________________________ _________________________________________ Re: SWDM Adjustment No. ________________ Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan: ____________________________________________________________________ Special District Overlays: ______________________________________________________________ Drainage Basin: _____________________________________________________________________ Stormwater Requirements: _____________________________________________________________ Part 9 ONSITE AND ADJACENT SENSITIVE AREAS River/Stream ________________________ Lake ______________________________ Wetlands ____________________________ Closed Depression ____________________ Floodplain ___________________________ Other _______________________________ _______________________________ Steep Slope __________________________ Erosion Hazard _______________________ Landslide Hazard ______________________ Coal Mine Hazard ______________________ Seismic Hazard _______________________ Habitat Protection ______________________ _____________________________________ None Peak flow standard & enhanced treatment None requested DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2022 City of Renton Surface Water Design Manual 6/22/2022 Ref 8-A-3 Part 10 SOILS Soil Type ______________________ ______________________ ______________________ ______________________ Slopes ________________________ ________________________ ________________________ ________________________ Erosion Potential _________________________ _________________________ _________________________ _________________________ High Groundwater Table (within 5 feet) Other ________________________________ Sole Source Aquifer Seeps/Springs Additional Sheets Attached Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE Core 2 – Offsite Analysis_________________ Sensitive/Critical Areas__________________ SEPA________________________________ LID Infeasibility________________________ Other________________________________ _____________________________________ LIMITATION / SITE CONSTRAINT _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: (name or description) Core Requirements (all 9 apply): Discharge at Natural Location Number of Natural Discharge Locations: Offsite Analysis Level: 1 / 2 / 3 dated:__________________ Flow Control (include facility summary sheet) Standard: _______________________________ or Exemption Number: ____________ Conveyance System Spill containment located at: _____________________________ Erosion and Sediment Control / Construction Stormwater Pollution Prevention CSWPP/CESCL/ESC Site Supervisor: _____________________ Contact Phone: _________________________ After Hours Phone: _________________________ Maintenance and Operation Responsibility (circle one): Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Liability Provided: Yes / No Provided with Final Drainage Report CBs and detention vaults Peak Control 06/08/2021 Parking Lot 0.14 to 0.25 in/hrLow infiltration rate low1%-5%Ur - Urban land DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 6/22/2022 2022 City of Renton Surface Water Design Manual 8-A-4 Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Water Quality (include facility summary sheet) Type (circle one): Basic / Sens. Lake / Enhanced Basic / Bog or Exemption No. _______________________ On-site BMPs Describe: Special Requirements (as applicable): Area Specific Drainage Requirements Type: SDO / MDP / BP / Shared Fac. / None Name: ________________________ Floodplain/Floodway Delineation Type (circle one): Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): _______________ Datum: Flood Protection Facilities Describe: Source Control (commercial / industrial land use) Describe land use: Describe any structural controls: Oil Control High-Use Site: Yes / No Treatment BMP: _________________________________ Maintenance Agreement: Yes / No with whom? _____________________________________ Other Drainage Structures Describe: Modular wetland Modular wetland Detention Vault Warehousing DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2022 City of Renton Surface Water Design Manual 6/22/2022 Ref 8-A-5 Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS 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 Control Pollutants Protect Existing and Proposed BMPs/Facilities Maintain Protective 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 BMPs/Facilities, restore operation of BMPs/Facilities as necessary Flag limits of sensitive areas and open space preservation areas Other _______________________ Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch) Flow Control Description Water Quality Description On-site BMPs Description Detention Infiltration Regional Facility Shared Facility Other _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Vegetated Flowpath Wetpool Filtration Oil Control Spill Control Other _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Full Dispersion Full Infiltration Limited Infiltration Rain Gardens Bioretention Permeable Pavement Basic Dispersion Soil Amendment Perforated Pipe Connection Other _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Modular wetland Vault with Flow Control Device DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 6/22/2022 2022 City of Renton Surface Water Design Manual 8-A-6 Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS Drainage Easement Covenant Native Growth Protection Covenant Tract 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 NoneNone Andrew Delia Digitally signed by Andrew Delia DN: C=US, E=andrew.delia@kimley-horn.com, O=Kimley-Horn, CN=Andrew Delia Date: 2023.11.01 16:33:49-07'00' DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 1 SECTION A – PROJECT OVERVIEW A.1 SITE LOCATI ON The 10.01-acre site is located along SW 10th Street between Lind Ave SW and Thomas Ave SW, in the City of Renton, King County, Washington. The legal description of the site is as follows: Lot 5 of Earlington Industrial Park No. 1, according to plat recorded in Volume 83 of plats, page 10, in King County, Washington. The site is also located in Flood Insurance Rate Map (FIRM) Map Number 53033C0976G, Panel 0976G. The site is not within the 100- or 500-year floodplain – see Appendix A for a map of floodplains around the site. A.2 EXISTING SITE CONDITIONS The site contains an existing warehouse of approximately 115,000 square feet. The site is bounded by SW 10th Street to the south, railroad easements to the west and east with existing industrial developments on the other side of both easements, and existing industrial developments to the north. Seneca Avenue SW splits the parcels adjacent to the site to the north and runs south to a dead end with a turnaround area approximately at the site’s north property line. The existing site is relatively flat, with a drop across the site of approximately 3 feet from the NE to SW corner. The portion of the site proposed to be improved contains some existing asphalt pavement in the SW corner, with the remainder of this area containing mostly hard-packed landscape. The existing site is approximately 33% impervious. Refer to Appendix A for a Pre-Development Drainage Area Map that includes additional information, including the 2-, 10-, and 100- year predeveloped flows. A.3 EXISTING ON -SITE STORMWATER SYSTEMS There are existing drainage structures on-site that convey stormwater runoff to the public storm main in SW 10th Street. It can be assumed that all stormwater runoff is collected by these existing structures and carried off-site. Building roof downspouts are tight-lined and connected to existing structures. Refer to the Pre-Development Drainage Area Map in Appendix A for additional information. A.4 ADJAC ENT PROPERTIES The site is generally at the same elevation as the adjacent properties, and therefore does not convey any by-pass flow to the adjacent properties or street right-of-way. The general drainage patterns and directions will be maintained in the proposed post-development condition. Refer to the Drainage Area Maps in Appendix A for additional information. A.5 PROJECT IMPACT ON ADJACENT AREAS The stormwater design intent of the project is to produce minimal impact on the adjacent properties and public drainage system. The project will capture and manage on-site stormwater runoff as is feasible within the threshold discharge area and will ensure no runoff enters adjacent sites. Areas of the site that currently sheet flow to the street right-of-way are outside of the threshold discharge area and will continue to do so at similar rates of flow. See Section D for an Offsite Analysis of the downstream drainage infrastructure. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 2 A.6 PROPOSED SITE CONDITIONS The project will construct a parking lot around an existing industrial building on-site that is to remain, with associated landscaping and utility improvements. Site stormwater runoff will be captured on-site by new catch basins, conveyed to a CMP detention system and modular wetland for treatment, then to the public storm main in SW 10th Street. The proposed project will disturb approximately 4.34 acres. The developed site is approximately 92% impervious. See Table 1 – Land Disturbing Activity below for additional information. Refer to Appendix A for a Post-Development Drainage Area Map that includes additional information, including the 2-, 10-, and 100- year developed flows. One curb ramp is proposed to be installed south of the existing building, disturbance of the base course is not anticipated, and the pavement material will be replaced in-kind. A.7 REVISIONS TO PRELIMINARY STORMWATER REPORT Not applicable. To be included in Final Stormwater Report SECTION B – CORE REQUIREMENTS B.1 APPLICABLE CORE REQUIREMENTS As the site has an existing impervious surface coverage of more than 35%, the proposed project is considered a redevelopment project. The project will create more than 2,000 square feet of hard surfaces and will disturb more than 7,000 square feet of land, and therefore the project is subject to Full Drainage Review per the 2022 City of Renton Surface Water Design Manual (SWDM) and must apply Core Requirements (CRs) #1 through #9 and Special Requirements (SRs) #1 through #6. See below for list of the Core and Special Requirements, the applicability of each to the project, and where additional information regarding compliance to each Core and Special Requirement may be found in this report. See Table 1 below for summary of Land Disturbing Activity for the project. TABLE 1 – LAND DISTURBING ACTIVITY EXISTING IMPERVIOUS SURFACE 1.54 AC NEW IMPERVIOUS SURFACE 3.794 AC REPLACED IMPERVIOUS SURFACE 1.44 AC NATIVE VEGETATION CONVERTED TO LAWN OR LANDSCAPING 0.08 AC TOTAL LAND DISTURBANCE 4.34 AC UNDISTURBED AREA 0.00 AC CR#1: Discharge at the Natural Location The project is required to adhere to CR#1, which states that, “All storm water runoff and surface water from a project must be discharged at the natural location so as not to be diverted onto or away from downstream properties. The manner in which stormwater runoff and surface water are discharged from the project site must not create a significant adverse impact to downhill properties or drainage facilities.” The existing site drainage patterns will be altered slightly to collect stormwater runoff in the post- developed condition. New on-site drainage structures will be installed to collect stormwater and convey it to the same public storm main in SW 10th Street as existing. No adverse impacts to downstream DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 3 drainage facilities are anticipated – refer to Section D for an Offsite Analysis of the drainage facilities downstream of the site. CR#2: Offsite Analysis All proposed projects must adhere to CR#2, which states that “projects must submit an offsite analysis report that assesses potential offsite drainage and water quality impacts associated with development of the project site, and that proposes appropriate mitigation of those impacts.” The initial permit submittal includes a Level 1 downstream analysis as described in section 1.2.2.1 of the SWDM. The Level 1 downstream analysis is a qualitative survey of the downstream system, and involves defining and mapping the downstream study area, reviewing all available information on the study area, field inspecting the study area, and describing the drainage system and any existing/predicted drainage and water quality problems. Refer to Section D of this report for additional information on how this project meets CR#2. CR#3: Flow Control Facilities As the project proposes more than 5,000 square feet of new plus replaced impervious surface, the project is required to adhere to CR#3, which states that, “All proposed projects, including redevelopment projects, must provide on-site flow control facilities to mitigate the impacts of storm and surface water runoff.” The flow control performance criteria are dependent on the results of the downstream analysis per Section 1.2.3.1 of the SWDM. Refer to Section E of this report for additional information on how this project meets CR#3. CR#4: Conveyance System The project is required to adhere to CR#4, which states that, “All engineered conveyance system elements for proposed projects must be analyzed, designed, and constructed to provide a minimum level of protection against overtopping, flooding, erosion, and structural failure.” For new systems, conveyance requirements are outlined in Section 1.2.4.1 of the SWDM. Refer to Section F of this report for additional information on how this project meets CR#4. CR#5: Construction Stormwater Pollution Prevention (CSWPP) The project shall comply with CR#5. Temporary erosion control plans will be developed for this project site complying with City of Renton and Washington State Department of Ecology requirements. As the site disturbance is greater than one acre in size, a Stormwater Pollution Prevention Plan (SWPPP) will be developed and included with the Final Stormwater Report. CR#6: Maintenance and Operations The project is required to adhere to CR#6, which states, “maintenance and operation of all drainage facilities is the responsibility of the applicant or property owner, except those facilities for which the City assumes maintenance and operation,” For industrial sites, maintenance and operation of flow control and water quality treatment facilities, including on-site BMPs, are the responsibility of the property owner. An Operations and Maintenance Manual has been prepared and provided with the Final Stormwater Report as part of the permit application for flow control and water quality facilities. See Appendix D of this report for the Operations and Maintenance Manual. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 4 CR#7: Financial Guarantees and Liability The project is required to adhere to CR#7, which states, “In accordance with Renton Municipal Code (RMC) 4-6-030, Community and Economic Development (CED) shall require all persons constructing any surface water facilities (including flow control/water quality facilities, conveyance systems, erosion control, and road drainage), to post with the City of Renton a bond, assignment of funds or certified check.” Provisions for the project to meet CR#7 shall be provided prior to final permit issuance. CR#8: Water Quality Facilities As a redevelopment project that proposes more than 5,000 square feet of new and replaced impervious surface, the project is required to adhere to CR#8, which states, “All proposed projects, including redevelopment projects, must provide water quality (WQ) facilities to treat the runoff from those new and replaced pollution-generating impervious surfaces and new pollution-generating pervious surfaces targeted for treatment.” The project proposes to use a Bio Clean Modular Wetlands Linear system to treat stormwater runoff. Refer to Section G of this report for additional information on how this project meets CR#8. CR#9: On-Site BMPs The project proposes more than 2,000 square feet of new and replaced impervious surface and therefore must meet CR#9, which states that “All proposed projects, including redevelopment projects, must provide on-site BMPs to mitigate the impacts of storm and surface water runoff generated by new impervious surface, new pervious surface, existing impervious surfaces, and replaced impervious surface targeted for mitigation.” The project will apply on-site BMPs to supplement the flow mitigation provided by on-site flow control facilities. This project will apply BMPs to the maximum extent feasible using lists specific to the project location, size, and impervious coverage in compliance with Section 1.2.9.2.2 of the SWDM, Large Lot BMP Requirements. Refer to Section H of this report for additional information on how this project meets CR#9. B.2 APPLICABLE SPECIAL REQUIREMENTS SR#1: Other Adopted Area-Specific Requirements Copies of all adopted basin plans, Salmon Conservation Plans (SCPs), Hazard Mitigation Plans, and Lake Management Plans will be obtained from the City of Renton and reviewed for compliance in the Final Drainage Report. SR#2: Flood Hazard Area Delineation The proposed project is not within or adjacent to a flood hazard area, so SR#2 is not applicable to the project. See Appendix A for the project site Flood Map. SR#3: Flood Protection Facilities The proposed project is not within or adjacent to a flood hazard area, so SR#2 is not applicable to the project. See Appendix A for the project site Flood Map. SR#4: Source Controls The project is required to adhere to SR#4, which states that, “When applicable per the Stormwater Pollution Prevention Manual, structural source control measures, such as car wash pads or dumpster area roofing, shall be applied to the entire site containing the proposed project, not just the project site.” DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 5 The proposed project is for continued warehousing services, and therefore will have no known sources of pollution that will require treatment beyond the treatment required by CR#8. SR#5: Oil Control The project is required to adhere to SR#5, which states that, “Projects proposing to develop or redevelop a high-use site must provide oil controls in addition to any other water quality controls required by this manual.” This project is not a high use site, so SR#5 is not applicable. SR#6: Aquifer Protection Area The project site is not within an Aquifer Protection Area (APA), so SR#6 is not applicable to the project. Refer to Appendix A for the APA Map. SECTION C – PRELIMINARY SOILS EVALUATION A Geotechnical Engineering Report, prepared by PanGeo, Inc., dated June 10, 2021 has been included with this report. Generally, the soils on site consist of a surficial layer of topsoil above two to four feet of fill soil overlying silt and clay. Refer to Appendix C for the report. SECTION D – OFFSITE ANALYSIS (CR#2) A Level 1 downstream analysis has been completed for the proposed project and has determined no existing drainage issues exist within the study area downstream of the site, and no predicted drainage or water quality issues will arise as part of the proposed project. Per the Section 1.2.2.1 of the SWDM, “the downstream analysis must consider the existing conveyance system(s) for a minimum flow path distance downstream of one-quarter mile and beyond that, as needed, to reach a point where the project site area constitutes less than 15% of the tributary area.” The distance from the project point of discharge to the public main in SW 10th Street to where the downstream system discharges to the receiving waterbody (Black River) is approximately 1,800 linear feet, or 0.35 miles, at which point the project site area constitutes less than 15% of the tributary area. This is the extent of the project downstream analysis – refer to Appendix A for a Downstream Analysis Study Area Map. Using the available City of Renton (COR) Maps and GIS Data, it was determined that there are no known drainage issues currently on file with COR or King County within the Downstream Analysis Study Area. A field inspection of the study area was also completed, and the condition of the existing drainage structures within the study area downstream of the project site are documented below. Refer to Appendix A for a Downstream Analysis Study Area Map for locations of structures documented below. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 6 Figure 1: Catch basin #1 along north side of SW 10th Street at the upstream end of the downstream storm system Figure 2: Catch basin #2 along south side of SW 10th Street at the upstream end of the downstream storm system DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 7 Figure 3: Catch basin #3 along south side of SW 10th Street Figure 4: Catch basin #4 along south side of SW 10th Street DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 8 Figure 5: Catch basin #5 along the curb at the NE corner of the intersection of SW 10th Street and Powell Avenue SW Figure 6: Catch basin #6 along the curb at the SE corner of the intersection of SW 10th Street and Powell Avenue SW DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 9 Figure 7: Catch basin #7 along the west side of Powell Ave SW near the intersection of Powell Avenue SW and SW 10th Street Figure 8: Catch basin #8 along the west side of Powell Ave SW near the intersection of Powell Avenue SW and SW 10th Street DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 10 Figure 9: Pipe daylight into ditch #1, with headwall slightly visible behind fallen tree Figure 10: Ditch #1 as seen from the west looking east DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 11 Figure 11: Culvert #1 daylight from the east looking west Figure 12: Culvert #1 daylight from the west looking east DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 12 Figure 13: Ditch #2 from the east looking west Figure 14: Culvert #2 daylight from the east looking west, with headwall partially visible behind brush DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 13 SECTION E – FLOW CONTROL FACILITIES (CR#3) Reference Section 15-A, City of Renton (COR) Flow Control Application Map, of the SWDM was used to determine that the project site is in a Peak Rate Flow Control Standard area – refer to Appendix A for a copy of the Flow Control Applications Map. The offsite analysis referenced in Section D of this report identified no issues downstream of the project site, so per Table 1.2.3.A of the SWDM, project flow control facilities must meet the Peak Rate Flow Control Standard, which matches the 2-, 10-, and 100- year peaks in the pre-developed and post-developed conditions within the threshold discharge area. Refer to Appendix A for Pre- and Post-Developed Drainage Area maps and a preliminary drainage plan. Per Chapter 3, Hydrologic Analysis and Design, of the SWDM, WWHM2012 is an approved model for stormwater runoff and water quality design in the City of Renton. WWHM2012 was used to model a detention vault that meets the Peak Rate Flow Control Standard. A vault of approximately 15,500 cubic feet was selected as the appropriate size for a flow control facility. Refer to Appendix B for an WWHM2012 report containing preliminary calculations of the detention vault. SECTION F – CONVEYANCE SYSTEM (CR#4) Pump systems may be used to convey water from one location or elevation to another within the project site provided they meet the design criteria specified for such systems in Section 4.2.3 and will be privately owned and maintained. Pump systems discharging flows from the project site that would not have discharged by gravity flow under existing site conditions will require an approved adjustment to Core Requirement #1 (see Section 1.4, “Adjustment Process“). These pump systems will be considered only when there is no other physical gravity alternative and they are necessary to prevent creation or aggravation of a flooding or erosion problem as specified in Section 1.2.2. Per Section 1.2.4.1 of the SWDM, new stormwater pipe systems shall be designed to convey and contain the 25-year peak flow for the developed condition. Stormwater conveyance system sizing calculations were completed using Autodesk Storm and Sanitary Analysis (SSA), and calculations are included in Appendix B. The proposed pump system for the site meets the following requirements in section 4.2.3.1 of the SWDM: The pump system must be privately owned and maintained. The pump system will be privately owned and maintained. The pump system shall be used to convey water from one location or elevation to another within the site. The pump station’s inlet and outlet are both within the site. The pump system must have a dual pump (alternating) equipped with an external alarm system. The system is currently designed as a duplex system and alarm elevations will be set when a manufacturer has been selected. The pump system shall not be used to circumvent any other City drainage requirements, and construction and operation of the pump system shall not violate any other City requirements. The pump system shall follow all City drainage requirements and will not be used to circumvent any other requirements. Construction and operation of the pump system will follow all City requirements. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 14 The gravity-flow components of the drainage system to and from the pump system must be designed so that pump failure does not result in flooding of a building or emergency access, or overflow to a location other than the natural discharge point for the site. In the event of a pump failure, overflow will happen to the natural discharge point for the site. The pump system shall have either installed emergency backup power or the ability for portable backup power generator in the event of a loss of primary power. If portable backup emergency power is provided, the appliance must include a description of how the backup power will be brought to the site during an emergency within an emergency response plan. In the event of a power outage, a building maintenance employee will connect the pump system to the backup power generator and turn the system on. Building maintenance employee will ensure proper operation of the pump system during emergency situations. The applicant must provide an emergency response plan that details how backup power will be activated during an emergency and include method for delivering to the site and energizing portable backup power. The emergency response plan must also describe response for pump failures including repair and replacement of damaged pumps/motors and generators. An emergency response plan will be submitted detailing the backup power plan as well as pump failure response. SECTION G – WATER QUALITY FACILITIES (CR#8) As the project proposes new plus replaced pollution generating impervious surface (PGIS) in excess of 5,000 square feet, the project will be required to provide enhanced basic water quality treatment. On-site soils are not suitable for infiltration or treatment under CR#8. Therefore, a Bio Clean Modular Wetlands Linear system is proposed to be located downstream of on-site flow control facilities to treat the runoff generated on-site. The Bio Clean Modular Wetlands Linear has attained a General Use Level Designation for Enhanced Treatment for the Washington Department of Ecology, and therefore is suitable to satisfy CR#8. Per the Section 6.2.1 of the SWDM, for treatment installed downstream of detention, the water quality design flow rate is the full 2-year release rate from the detention facility. Refer to Figure 15 below for the full 2-year release rate as determined using WWHM2012. See Appendix B for WWHM2012 calculations for water quality and flow control. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 15 Figure 15 – Water quality flow rate SECTION H – ON-SITE BMPS (CR#9) As the proposed project site is larger than 22,000 square feet, per Section 1.2.9.2.2 of the SWDM the project must apply on-site BMPs as specified in the requirements of that section and outlined below: Full Dispersion Per Section C.2.1.1 of Appendix C of the SWDM, “the total area of impervious surface being fully dispersed must be no more than 15% of the total area of native vegetated surface being preserved by a recorded tract, easement, or covenant on the site.” As the site improvements will consist primarily of impervious surface for parking that will need to be collected a managed on-site, there will not be enough native vegetation available, and full dispersion is not feasible. Full Infiltration Per Section C.2.2.2 of Appendix C of the SWDM, for full infiltration to be feasible and applicable to manage stormwater runoff from target surfaces, “existing soils must be coarse sands or cobbles or medium sands and cannot be comprised of fill materials where the infiltration device will be located.” Per an initial subsurface investigation completed by PanGeo, the site soils consist of fill overlying silt and clay, with a design infiltration rate of between 0.14 and 0.25 inches per hour. Therefore, full infiltration is not feasible. The geotechnical report prepared by PanGeo, Inc., and dated June 10, 2021 is available in Appendix C of this report. Limited Infiltration Per Section C.2.3.2 of Appendix C of the SWDM, “the minimum design requirements for limited infiltration are the same as those for full infiltration, except infiltration depressions are excluded and existing soils in the location of the infiltration device may be fine sands, loamy sands, sandy loams, or loams.” For the project, limited infiltration is not feasible given the existing soil conditions. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 16 Basic Dispersion Per Section C.2.4 of Appendix C of the SWDM, “basic dispersion is considered infeasible and not required for projects that cannot meet the minimum design requirements” list in Section C.2.4. The project proposes mostly new impervious surface and cannot meet the minimum vegetated flow path requirements for Basic Dispersion BMPs. Therefore, Basic Dispersion is not feasible. Farmland Dispersion This BMP does not apply to the City of Renton per Section C.2.5 of the SWDM. Bioretention Per Section C.2.6 of Appendix C of the SWDM, bioretention is infeasible “where the only area available for siting would threaten the safety or reliability of pre-existing underground utilities, pre-existing underground storage tanks, pre-existing structures, or pre-existing road or parking lot surfaces.” For the proposed parking, due to the flat nature of the site and the location of the existing storm drain tie-in on- site, the project will be unable to direct stormwater to the areas available for siting bioretention. Therefore, bioretention is not feasible. Permeable Pavement Per Section C.2.7 of Appendix C of the SWDM, permeable pavement is infeasible Rainwater Harvesting Per Section C.2.8 of Appendix C of the SWDM, “rainwater harvesting means the collection and storage of roof runoff for domestic or irrigation uses.” As there are no proposed modifications to the existing building and no proposed new structures as part of the project, rainwater harvesting is not applicable. Reduced Impervious Surface Credit The Reduced Impervious Surface Credit is not applicable to the project. Native Growth Retention Credit The Native Growth Retention Credit is not applicable to the project. Perforated Pipe Connection As the site soils are not conducive to infiltration, Perforated Pipe Connections that allow for infiltration of stormwater runoff are not applicable to the project. See Appendix C of this report for project geotechnical report. Rain Gardens Per Section C.2.12 of Appendix C of the SWDM, infeasibility criteria for rain gardens are the same as for bioretention. Therefore, rain gardens are not feasible. Soil Amendment Native soil retention and reuse will be used on-site to the maximum extent feasible. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 17 Tree Retention Credit Existing trees on-site will be protected and retained to the maximum extent feasible. There are no existing trees within the project limits of disturbance that are proposed to be removed. Vegetated Roofs As the project proposes to protect the existing building and make no building modifications, and does not propose any new structures, vegetated roof would not be feasible for the project. SECTION I – OTHER PERMITS Construction of this project and its stormwater facilities will require the following additional permits: Construction Stormwater General Permit – Washington Department of Ecology Status: Not yet submitted SECTION J – OPERATIONS AND MAINTENANCE MANUAL (CR#6) An Operations and Maintenance Manual that addresses the maintenance and operation of all on-site drainage facilities has been prepared for the project and is included in Appendix D of this report. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 18 SECTION M – APPENDICES APPENDIX A: MAPS 1. VICINITY MAP DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D AERIAL OBTAINED FROM NEAR MAPS SW 10TH S T SW GRAD Y W A Y SE N E C A A V E W A Y LI N D A V E S W TH O M A S A V E S W SW 12TH S T DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 19 2. FLOOD INSURANCE RATE MAP DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Site Location DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 20 3. PRE-DEVELOPMENT DRAINAGE AREA MAP DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D D © 60 0 S W 1 0 T H S T R E E T PR E P A R E D F O R EV 6 0 0 L L C PR E - D E V E L O P M E N T DR A I N A G E A R E A M A P A-1 LEGEND DRAINAGE DIVIDE DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 21 4. POST-DEVELOPMENT DRAINAGE AREA MAP DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D WC WC WC WC WC WC CO M P A C T CO M P A C T CO M P A C T CO M P A C T WC WC WC WC WC WC WC WC WC WC 24.0'24.0'24.0' 9. 0 ' 24.0'24.0' 8. 5 ' 17.0'24.0' NO PA R K I N G NO PA R K I N G NO PA R K I N G NO PA R K I N G NO PA R K I N G NO PA R K I N G NO PA R K I N G NO PARKING D © 60 0 S W 1 0 T H S T R E E T PR E P A R E D F O R EV 6 0 0 L L C PO S T - D E V E L O P M E N T DR A I N A G E A R E A M A P A-1 LEGEND DRAINAGE DIVIDE DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 22 5. PROPOSED DRAINAGE PLAN DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D D WC CO M P A C T CO M P A C T CO M P A C T CO M P A C T WC NO PA R K I N G NO PA R K I N G NO PA R K I N G NO PA R K I N G NO PA R K I N G NO PA R K I N G NO PA R K I N G NO PARKING WC WC WCWCWCWCWCWCWC WC WC WC WC WC IN COMPLIANCE WITH CITY OF RENTON STANDARDS 18 600 SW 10TH PARKING LOT 60 0 S W 1 0 T H P A R K I N G L O T PR : LU A : C: 60 0 S W 1 0 T H P A R K I N G L O T NORTH GRADING & STORM DRAIN PLAN 6 C-103 LEGEND PROPERTY LINE SW 10TH S T R E E T SE N E C A A V E S W C- 1 0 3 RIDGE LINE STORM DRAIN PIPE CATCH BASIN TYPE 1P CATCH BASIN TYPE 2 MANHOLE (REFER TO PLAN FOR TYPE) ACCESS HATCH (SEE SHEET C-507) CURB INLET PARKING LIGHTS SPOT ELEVATION ABBREVIATIONS EP EDGE OF PAVEMENT TC TOP OF CURB BC BACK OF CURB FL FLOW LINE LP LOW POINT HP HIGH POINT ME MATCH EXISTING CB CATCH BASIN LF LINEAR FEET CMP CORRUGATED METAL PIPE VALVE 1"=5' 1 BOX DETAIL C-103 11/01/2023 11/01/202 3 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 23 6. AQUIFER PROTECTION AREA MAP DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Esri, HERE, Garmin, (c) OpenStreetMap contributor s, and the GIS usercommunity Zone 1 Zone 1 Modified Zone 2 Renton Water District ³ Data Sources: City of Renton, King County, ESRI This document is a graphic representation, not guaranteedto survey accuracy, and is based on the best informationavailable as of the date shown. This map is intended forCity display purposes only. Coordinate System: NAD 1983 HARN StatePlane Washington North FIPS 4601 FeetProjection: Lambert Conformal ConicDatum: North American 1983 HARN Date: 05/15/2020 0 0.5 10.25 Miles Site Location DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 24 7. DOWNSTREAM ANALYSIS STUDY AREA MAP DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 4,514752 600 SW 10th St This map is a user generated static output from an Internet mapping site and is for reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. THIS MAP IS NOT TO BE USED FOR NAVIGATIONWGS_1984_Web_Mercator_Auxiliary_Sphere Notes Downstream Analysis Study Area Map 06/08/2021 Legend 512 0 256 512 Feet Information Technology - GIS RentonMapSupport@Rentonwa.gov Network Structures Access Riser Inlet Manhole Utility Vault Clean Out Unknown Control Structure Pump Station Discharge Point Water Quality Detention Facilities Pond Tank Vault Bioswale Wetland Other Surface Water Main Culvert Open Drains Facility Outline Private Network Structures Access Riser Inlet Manhole Clean Out Utility Vault Unknown Private Control Structure Private Pump Station Private Discharge Point Private Water Quality Private Detention Facilities Tank, No Stormwater Wetland, No; Natural Wetland, No Filter Strip, No Infiltration Trench, No Vault, No Pond, No; Pond, Unknown Bioswale, No Stormtech Chamber, No Other, No Private Pipe Private Culvert Private Open Drains Private Facility Outline Fence Stormwater Ponds Facility Transfer Inactive Structure Inactive Pipe Inactive Water Quality Inactive Detention Facilities Drainage Complaints Known Drainage Issues Renton Culvert #2 Culvert #1 Ditch #2 Ditch #1 CB#8 CB#7 CB#6 CB#5 CB#4 CB#3 CB#2 CB#1 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 25 APPENDIX B: CALCULATIONS 1. FLOW CONTROL CALCULATIONS DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D WWHM2012 PROJECT REPORT DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:10:27 PM Page 2 General Model Information Project Name:600 10th Ave Site Name: Site Address: City: Report Date:10/18/2023 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2021/08/18 Version:4.2.18 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:10:27 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 2.8 Pervious Total 2.8 Impervious Land Use acre PARKING FLAT 1.54 Impervious Total 1.54 Basin Total 4.34 Element Flows To: Surface Interflow Groundwater DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:10:27 PM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre A B, Lawn, Flat 0.55 Pervious Total 0.55 Impervious Land Use acre PARKING FLAT 3.79 Impervious Total 3.79 Basin Total 4.34 Element Flows To: Surface Interflow Groundwater Tank 1 Tank 1 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:10:27 PM Page 5 Routing Elements Predeveloped Routing DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:10:27 PM Page 6 Mitigated Routing Tank 1 Dimensions Depth:6 ft. Tank Type:Circular Diameter:6 ft. Length:800 ft. Discharge Structure Riser Height:5 ft. Riser Diameter:18 in. Notch Type:Rectangular Notch Width:0.060 ft. Notch Height:2.400 ft. Orifice 1 Diameter:2.98 in.Elevation:0 ft. Element Flows To: Outlet 1 Outlet 2 Tank Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.000 0.000 0.000 0.000 0.0667 0.023 0.001 0.062 0.000 0.1333 0.032 0.002 0.088 0.000 0.2000 0.039 0.005 0.107 0.000 0.2667 0.045 0.008 0.124 0.000 0.3333 0.050 0.011 0.139 0.000 0.4000 0.055 0.014 0.152 0.000 0.4667 0.059 0.018 0.164 0.000 0.5333 0.062 0.022 0.176 0.000 0.6000 0.066 0.027 0.186 0.000 0.6667 0.069 0.031 0.196 0.000 0.7333 0.072 0.036 0.206 0.000 0.8000 0.074 0.041 0.215 0.000 0.8667 0.077 0.046 0.224 0.000 0.9333 0.079 0.051 0.232 0.000 1.0000 0.082 0.056 0.241 0.000 1.0667 0.084 0.062 0.248 0.000 1.1333 0.086 0.068 0.256 0.000 1.2000 0.088 0.073 0.264 0.000 1.2667 0.089 0.079 0.271 0.000 1.3333 0.091 0.085 0.278 0.000 1.4000 0.093 0.092 0.285 0.000 1.4667 0.094 0.098 0.291 0.000 1.5333 0.096 0.104 0.298 0.000 1.6000 0.097 0.111 0.304 0.000 1.6667 0.098 0.117 0.311 0.000 1.7333 0.099 0.124 0.317 0.000 1.8000 0.101 0.131 0.323 0.000 1.8667 0.102 0.137 0.329 0.000 1.9333 0.103 0.144 0.335 0.000 2.0000 0.103 0.151 0.340 0.000 2.0667 0.104 0.158 0.346 0.000 2.1333 0.105 0.165 0.352 0.000 2.2000 0.106 0.172 0.357 0.000 2.2667 0.106 0.179 0.362 0.000 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:10:27 PM Page 7 2.3333 0.107 0.186 0.368 0.000 2.4000 0.108 0.194 0.373 0.000 2.4667 0.108 0.201 0.378 0.000 2.5333 0.108 0.208 0.383 0.000 2.6000 0.109 0.215 0.388 0.000 2.6667 0.109 0.223 0.396 0.000 2.7333 0.109 0.230 0.407 0.000 2.8000 0.109 0.237 0.420 0.000 2.8667 0.110 0.244 0.434 0.000 2.9333 0.110 0.252 0.448 0.000 3.0000 0.110 0.259 0.463 0.000 3.0667 0.110 0.267 0.479 0.000 3.1333 0.110 0.274 0.496 0.000 3.2000 0.109 0.281 0.512 0.000 3.2667 0.109 0.289 0.529 0.000 3.3333 0.109 0.296 0.547 0.000 3.4000 0.109 0.303 0.564 0.000 3.4667 0.108 0.310 0.582 0.000 3.5333 0.108 0.318 0.599 0.000 3.6000 0.108 0.325 0.617 0.000 3.6667 0.107 0.332 0.637 0.000 3.7333 0.106 0.339 0.658 0.000 3.8000 0.106 0.346 0.679 0.000 3.8667 0.105 0.353 0.701 0.000 3.9333 0.104 0.360 0.724 0.000 4.0000 0.103 0.367 0.831 0.000 4.0667 0.103 0.374 0.860 0.000 4.1333 0.102 0.381 0.890 0.000 4.2000 0.101 0.388 0.921 0.000 4.2667 0.099 0.394 0.951 0.000 4.3333 0.098 0.401 0.983 0.000 4.4000 0.097 0.408 1.015 0.000 4.4667 0.096 0.414 1.047 0.000 4.5333 0.094 0.420 1.080 0.000 4.6000 0.093 0.427 1.113 0.000 4.6667 0.091 0.433 1.147 0.000 4.7333 0.089 0.439 1.181 0.000 4.8000 0.088 0.445 1.216 0.000 4.8667 0.086 0.451 1.251 0.000 4.9333 0.084 0.456 1.287 0.000 5.0000 0.082 0.462 1.323 0.000 5.0667 0.079 0.467 1.600 0.000 5.1333 0.077 0.473 2.102 0.000 5.2000 0.074 0.478 2.738 0.000 5.2667 0.072 0.483 3.461 0.000 5.3333 0.069 0.487 4.223 0.000 5.4000 0.066 0.492 4.976 0.000 5.4667 0.062 0.496 5.674 0.000 5.5333 0.059 0.500 6.275 0.000 5.6000 0.055 0.504 6.756 0.000 5.6667 0.050 0.507 7.112 0.000 5.7333 0.045 0.511 7.375 0.000 5.8000 0.039 0.514 7.703 0.000 5.8667 0.032 0.516 7.965 0.000 5.9333 0.023 0.518 8.218 0.000 6.0000 0.000 0.519 8.461 0.000 6.0667 0.000 0.000 8.697 0.000 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:10:27 PM Page 8 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:10:27 PM Page 9 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:2.8 Total Impervious Area:1.54 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.55 Total Impervious Area:3.79 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.781014 5 year 1.083015 10 year 1.303441 25 year 1.605962 50 year 1.849241 100 year 2.108284 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.418417 5 year 0.591552 10 year 0.730766 25 year 0.937744 50 year 1.116674 100 year 1.318764 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 1.167 0.407 1950 1.147 0.379 1951 0.720 0.530 1952 0.472 0.328 1953 0.492 0.344 1954 0.628 0.325 1955 0.671 0.556 1956 0.671 0.401 1957 0.872 0.467 1958 0.587 0.384 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:02 PM Page 10 1959 0.499 0.360 1960 0.760 0.530 1961 0.712 0.346 1962 0.509 0.307 1963 0.690 0.315 1964 0.617 0.338 1965 0.927 0.363 1966 0.515 0.335 1967 1.159 0.487 1968 1.058 0.354 1969 0.838 0.382 1970 0.721 0.364 1971 0.863 0.343 1972 1.122 0.540 1973 0.450 0.350 1974 0.845 0.310 1975 0.895 0.539 1976 0.651 0.344 1977 0.608 0.331 1978 0.742 0.415 1979 0.888 0.325 1980 1.311 0.429 1981 0.775 0.368 1982 1.318 0.714 1983 0.805 0.410 1984 0.576 0.344 1985 0.787 0.375 1986 0.720 0.627 1987 0.908 0.661 1988 0.497 0.324 1989 0.622 0.291 1990 2.099 1.074 1991 1.493 0.865 1992 0.571 0.364 1993 0.442 0.334 1994 0.415 0.286 1995 0.670 0.368 1996 0.963 0.601 1997 0.834 0.683 1998 0.661 0.343 1999 1.723 0.550 2000 0.785 0.392 2001 0.691 0.325 2002 1.165 0.646 2003 0.906 0.332 2004 1.570 1.800 2005 0.728 0.536 2006 0.681 0.382 2007 1.904 1.082 2008 1.464 1.154 2009 0.895 0.522 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 2.0990 1.8000 2 1.9039 1.1538 3 1.7231 1.0822 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:02 PM Page 11 4 1.5699 1.0738 5 1.4934 0.8647 6 1.4639 0.7144 7 1.3185 0.6826 8 1.3107 0.6611 9 1.1667 0.6464 10 1.1651 0.6269 11 1.1591 0.6009 12 1.1473 0.5564 13 1.1215 0.5495 14 1.0584 0.5404 15 0.9625 0.5386 16 0.9269 0.5358 17 0.9084 0.5302 18 0.9063 0.5296 19 0.8951 0.5218 20 0.8951 0.4875 21 0.8877 0.4666 22 0.8718 0.4286 23 0.8628 0.4153 24 0.8448 0.4101 25 0.8381 0.4068 26 0.8340 0.4007 27 0.8050 0.3917 28 0.7866 0.3841 29 0.7849 0.3815 30 0.7749 0.3815 31 0.7597 0.3786 32 0.7416 0.3750 33 0.7284 0.3677 34 0.7213 0.3676 35 0.7203 0.3645 36 0.7200 0.3641 37 0.7119 0.3626 38 0.6913 0.3599 39 0.6897 0.3540 40 0.6814 0.3496 41 0.6714 0.3462 42 0.6706 0.3443 43 0.6698 0.3439 44 0.6611 0.3437 45 0.6507 0.3434 46 0.6283 0.3432 47 0.6218 0.3384 48 0.6171 0.3353 49 0.6084 0.3343 50 0.5868 0.3318 51 0.5758 0.3314 52 0.5712 0.3283 53 0.5154 0.3253 54 0.5093 0.3251 55 0.4992 0.3248 56 0.4972 0.3236 57 0.4915 0.3151 58 0.4718 0.3096 59 0.4502 0.3074 60 0.4418 0.2910 61 0.4148 0.2864 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:02 PM Page 12 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:02 PM Page 13 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.3905 1442 1427 98 Pass 0.4052 1272 1192 93 Pass 0.4200 1140 1035 90 Pass 0.4347 1004 895 89 Pass 0.4494 900 794 88 Pass 0.4642 796 706 88 Pass 0.4789 712 625 87 Pass 0.4936 650 565 86 Pass 0.5084 576 513 89 Pass 0.5231 511 445 87 Pass 0.5379 473 393 83 Pass 0.5526 443 350 79 Pass 0.5673 400 329 82 Pass 0.5821 373 302 80 Pass 0.5968 342 274 80 Pass 0.6115 317 245 77 Pass 0.6263 295 202 68 Pass 0.6410 280 177 63 Pass 0.6557 257 151 58 Pass 0.6705 232 136 58 Pass 0.6852 212 120 56 Pass 0.6999 195 110 56 Pass 0.7147 182 106 58 Pass 0.7294 166 103 62 Pass 0.7441 153 101 66 Pass 0.7589 144 98 68 Pass 0.7736 138 98 71 Pass 0.7883 123 95 77 Pass 0.8031 118 94 79 Pass 0.8178 114 91 79 Pass 0.8325 110 90 81 Pass 0.8473 105 88 83 Pass 0.8620 101 84 83 Pass 0.8768 96 81 84 Pass 0.8915 88 79 89 Pass 0.9062 83 76 91 Pass 0.9210 75 74 98 Pass 0.9357 70 72 102 Pass 0.9504 69 68 98 Pass 0.9652 63 67 106 Pass 0.9799 60 66 110 Pass 0.9946 58 57 98 Pass 1.0094 55 54 98 Pass 1.0241 50 47 94 Pass 1.0388 48 46 95 Pass 1.0536 48 38 79 Pass 1.0683 45 32 71 Pass 1.0830 42 27 64 Pass 1.0978 41 27 65 Pass 1.1125 40 24 60 Pass 1.1272 38 21 55 Pass 1.1420 36 19 52 Pass 1.1567 34 17 50 Pass DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:02 PM Page 14 1.1714 30 16 53 Pass 1.1862 29 15 51 Pass 1.2009 28 15 53 Pass 1.2156 25 15 60 Pass 1.2304 24 14 58 Pass 1.2451 23 13 56 Pass 1.2599 22 12 54 Pass 1.2746 21 11 52 Pass 1.2893 21 10 47 Pass 1.3041 21 10 47 Pass 1.3188 18 7 38 Pass 1.3335 15 5 33 Pass 1.3483 15 5 33 Pass 1.3630 14 5 35 Pass 1.3777 14 5 35 Pass 1.3925 14 5 35 Pass 1.4072 14 5 35 Pass 1.4219 13 5 38 Pass 1.4367 12 4 33 Pass 1.4514 12 4 33 Pass 1.4661 11 4 36 Pass 1.4809 10 4 40 Pass 1.4956 8 4 50 Pass 1.5103 8 4 50 Pass 1.5251 6 4 66 Pass 1.5398 6 4 66 Pass 1.5545 5 3 60 Pass 1.5693 5 3 60 Pass 1.5840 4 3 75 Pass 1.5988 3 3 100 Pass 1.6135 3 3 100 Pass 1.6282 3 3 100 Pass 1.6430 3 3 100 Pass 1.6577 3 3 100 Pass 1.6724 3 2 66 Pass 1.6872 3 2 66 Pass 1.7019 3 2 66 Pass 1.7166 3 2 66 Pass 1.7314 2 2 100 Pass 1.7461 2 2 100 Pass 1.7608 2 2 100 Pass 1.7756 2 1 50 Pass 1.7903 2 1 50 Pass 1.8050 2 0 0 Pass 1.8198 2 0 0 Pass 1.8345 2 0 0 Pass 1.8492 2 0 0 Pass DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:02 PM Page 15 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0.3704 acre-feet On-line facility target flow:0.2534 cfs. Adjusted for 15 min:0.2534 cfs. Off-line facility target flow:0.1624 cfs. Adjusted for 15 min:0.1624 cfs. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:02 PM Page 16 LID Report DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:26 PM Page 17 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. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:26 PM Page 18 Appendix Predeveloped Schematic DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:27 PM Page 19 Mitigated Schematic DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 20 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 26 600 10th Ave.wdm MESSU 25 Pre600 10th Ave.MES 27 Pre600 10th Ave.L61 28 Pre600 10th Ave.L62 30 POC600 10th Ave1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 16 IMPLND 11 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 *** 16 C, Lawn, Flat 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 16 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 16 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 21 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 16 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 16 0 4.5 0.03 400 0.05 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 16 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 16 0.1 0.25 0.25 6 0.5 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 16 0 0 0 0 2.5 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 11 PARKING/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 11 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 11 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 11 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 11 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 11 0 0 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 22 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 11 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 16 2.8 COPY 501 12 PERLND 16 2.8 COPY 501 13 IMPLND 11 1.54 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 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 23 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 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 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 END MASS-LINK END RUN DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 24 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 26 600 10th Ave.wdm MESSU 25 Mit600 10th Ave.MES 27 Mit600 10th Ave.L61 28 Mit600 10th Ave.L62 30 POC600 10th Ave1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 7 IMPLND 11 RCHRES 1 COPY 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Tank 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 # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 25 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 *** 11 PARKING/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 11 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 11 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 11 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 11 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 26 # - # ***PETMAX PETMIN 11 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 11 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 7 0.55 RCHRES 1 2 PERLND 7 0.55 RCHRES 1 3 IMPLND 11 3.79 RCHRES 1 5 ******Routing****** PERLND 7 0.55 COPY 1 12 IMPLND 11 3.79 COPY 1 15 PERLND 7 0.55 COPY 1 13 RCHRES 1 1 COPY 501 16 END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** 1 Tank 1 1 1 1 1 28 0 1 END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO HYDR-PARM1 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 * * * * * * * * * * * * * * *** 1 0 1 0 0 4 0 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 27 1 1 0.15 0.0 0.0 0.5 0.0 END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> 1 0 4.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES FTABLE 1 91 4 Depth Area Volume Outflow1 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (ft/sec) (Minutes)*** 0.000000 0.000000 0.000000 0.000000 0.066667 0.023101 0.001029 0.062222 0.133333 0.032486 0.002901 0.087996 0.200000 0.039560 0.005311 0.107772 0.266667 0.045417 0.008149 0.124444 0.333333 0.050482 0.011349 0.139133 0.400000 0.054974 0.014867 0.152413 0.466667 0.059024 0.018669 0.164625 0.533333 0.062718 0.022729 0.175991 0.600000 0.066116 0.027025 0.186667 0.666667 0.069261 0.031539 0.196764 0.733333 0.072186 0.036255 0.206368 0.800000 0.074917 0.041159 0.215544 0.866667 0.077474 0.046240 0.224345 0.933333 0.079875 0.051486 0.232814 1.000000 0.082133 0.056887 0.240986 1.066667 0.084259 0.062434 0.248889 1.133333 0.086263 0.068119 0.256549 1.200000 0.088154 0.073933 0.263987 1.266667 0.089939 0.079870 0.271220 1.333333 0.091623 0.085923 0.278266 1.400000 0.093213 0.092084 0.285138 1.466667 0.094712 0.098349 0.291848 1.533333 0.096126 0.104711 0.298407 1.600000 0.097458 0.111164 0.304825 1.666667 0.098711 0.117704 0.311111 1.733333 0.099889 0.124324 0.317272 1.800000 0.100993 0.131020 0.323316 1.866667 0.102027 0.137788 0.329249 1.933333 0.102992 0.144622 0.335077 2.000000 0.103891 0.151519 0.340805 2.066667 0.104724 0.158473 0.346439 2.133333 0.105495 0.165481 0.351982 2.200000 0.106203 0.172538 0.357440 2.266667 0.106850 0.179640 0.362815 2.333333 0.107438 0.186783 0.368112 2.400000 0.107966 0.193964 0.373333 2.466667 0.108438 0.201177 0.378483 2.533333 0.108851 0.208421 0.383564 2.600000 0.109209 0.215690 0.388578 2.666667 0.109511 0.222981 0.396921 2.733333 0.109757 0.230290 0.407885 2.800000 0.109948 0.237614 0.420402 2.866667 0.110084 0.244948 0.434065 2.933333 0.110166 0.252290 0.448624 3.000000 0.110193 0.259636 0.463902 3.066667 0.110166 0.266981 0.479762 3.133333 0.110084 0.274323 0.496094 3.200000 0.109948 0.281658 0.512804 3.266667 0.109757 0.288982 0.529812 3.333333 0.109511 0.296291 0.547047 3.400000 0.109209 0.303582 0.564446 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 28 3.466667 0.108851 0.310851 0.581952 3.533333 0.108438 0.318094 0.599512 3.600000 0.107966 0.325308 0.617078 3.666667 0.107438 0.332488 0.637540 3.733333 0.106850 0.339632 0.658480 3.800000 0.106203 0.346734 0.679883 3.866667 0.105495 0.353791 0.701736 3.933333 0.104724 0.360798 0.724028 4.000000 0.103891 0.367753 0.831536 4.066667 0.102992 0.374649 0.860800 4.133333 0.102027 0.381483 0.890612 4.200000 0.100993 0.388251 0.920960 4.266667 0.099889 0.394948 0.951834 4.333333 0.098711 0.401568 0.983221 4.400000 0.097458 0.408107 1.015114 4.466667 0.096126 0.414561 1.047502 4.533333 0.094712 0.420922 1.080376 4.600000 0.093213 0.427187 1.113728 4.666667 0.091623 0.433349 1.147551 4.733333 0.089939 0.439401 1.181837 4.800000 0.088154 0.445338 1.216578 4.866667 0.086263 0.451153 1.251768 4.933333 0.084259 0.456838 1.287400 5.000000 0.082133 0.462385 1.323469 5.066667 0.079875 0.467786 1.600744 5.133333 0.077474 0.473032 2.102071 5.200000 0.074917 0.478112 2.738604 5.266667 0.072186 0.483017 3.461475 5.333333 0.069261 0.487733 4.223660 5.400000 0.066116 0.492247 4.976809 5.466667 0.062718 0.496543 5.674081 5.533333 0.059024 0.500602 6.275677 5.600000 0.054974 0.504404 6.756105 5.666667 0.050482 0.507922 7.112763 5.733333 0.045417 0.511123 7.375623 5.800000 0.039560 0.513961 7.703487 5.866667 0.032486 0.516371 7.965633 5.933333 0.023101 0.518242 8.217983 6.000000 0.001000 0.519272 8.461568 END FTABLE 1 END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 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*** RCHRES 1 HYDR RO 1 1 1 WDM 1002 FLOW ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1003 STAG ENGL REPL COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 2 PERLND PWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 2 MASS-LINK 3 PERLND PWATER IFWO 0.083333 RCHRES INFLOW IVOL DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 29 END MASS-LINK 3 MASS-LINK 5 IMPLND IWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 5 MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 MASS-LINK 16 RCHRES ROFLOW COPY INPUT MEAN END MASS-LINK 16 END MASS-LINK END RUN DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 30 Predeveloped HSPF Message File DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 31 Mitigated HSPF Message File DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 10th Ave 10/18/2023 5:11:29 PM Page 32 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. 2005-2023; 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 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 26 2. CONVEYANCE SYSTEM CALCULATIONS DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Project Description 600sw10th.SPF Project Options CFS Elevation SCS TR-55 User-Defined Kinematic Wave YES NO Analysis Options Apr 05, 2022 00:00:00 Apr 06, 2022 00:00:00 Apr 05, 2022 00:00:00 0 days 0 01:00:00 days hh:mm:ss 0 00:05:00 days hh:mm:ss 0 00:05:00 days hh:mm:ss 30 seconds Number of Elements Qty 1 4 8 6 1 0 0 1 8 0 6 0 1 1 0 0 0 Rainfall Details SN Rain Gage Data Data Source Rainfall Rain State County Return Rainfall Rainfall ID Source ID Type Units Period Depth Distribution (years)(inches) 1 Rain Gage-01 Time Series TS-01 Cumulative inches Washington King 25 3.00 Seattle, WA 24-hr Outlets ..................................................... Pollutants ......................................................... Land Uses ........................................................ Links.................................................................. Channels ................................................. Pipes ........................................................ Pumps ..................................................... Orifices .................................................... Weirs ....................................................... Nodes................................................................ Junctions ................................................. Outfalls .................................................... Flow Diversions ....................................... Inlets ........................................................ Storage Nodes ......................................... Runoff (Dry Weather) Time Step ..................... Runoff (Wet Weather) Time Step .................... Reporting Time Step ........................................ Routing Time Step ........................................... Rain Gages ...................................................... Subbasins......................................................... Enable Overflow Ponding at Nodes ................. Skip Steady State Analysis Time Periods ........ Start Analysis On ............................................. End Analysis On ............................................... Start Reporting On ........................................... Antecedent Dry Days ....................................... File Name ......................................................... Flow Units ........................................................ Elevation Type ................................................. Hydrology Method ............................................ Time of Concentration (TOC) Method ............. Link Routing Method ........................................ DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Subbasin Summary SN Subbasin Area Peak Rate Weighted Total Total Total Peak Time of ID Factor Curve Rainfall Runoff Runoff Runoff Concentration Number Volume (ac)(in)(in)(ac-in)(cfs)(days hh:mm:ss) 1 Sub-01 0.86 484.00 98.00 3.00 2.77 2.38 1.51 0 00:02:06 2 Sub-02 1.08 484.00 98.00 3.00 2.77 2.99 1.91 0 00:01:42 3 Sub-03 0.71 484.00 98.00 3.00 2.77 1.97 1.25 0 00:01:48 4 Sub-04 0.80 484.00 98.00 3.00 2.77 2.21 1.41 0 00:02:24 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Node Summary SN Element Element Invert Ground/Rim Initial Surcharge Ponded Peak Max HGL Max Min Time of Total Total Time ID Type Elevation (Max)Water Elevation Area Inflow Elevation Surcharge Freeboard Peak Flooded Flooded Elevation Elevation Attained Depth Attained Flooding Volume Attained Occurrence (ft)(ft)(ft)(ft)(ft²)(cfs)(ft)(ft)(ft)(days hh:mm)(ac-in)(min) 1 CB-01 Junction 18.36 21.78 0.00 21.78 200.00 2.53 18.97 0.00 2.81 0 00:00 0.00 0.00 2 CB-02 Junction 16.79 21.78 0.00 21.78 200.00 5.73 17.92 0.00 3.86 0 00:00 0.00 0.00 3 CB-03 Junction 18.75 21.92 0.00 21.92 200.00 1.23 19.14 0.00 2.79 0 00:00 0.00 0.00 4 CB-04 Junction 18.00 21.68 0.00 21.68 200.00 1.47 18.42 0.00 3.26 0 00:00 0.00 0.00 5 CB-FCMH Junction 14.33 22.84 0.00 22.84 200.00 5.74 16.91 0.00 5.38 0 00:00 0.00 0.00 8 Stor Storage Node 14.33 22.33 14.33 22.29 60000.00 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Link Summary SN Element Element From To (Outlet)Length Inlet Outlet Average Diameter or Manning's Peak Design Flow Peak Flow/Peak Flow Peak Flow Peak Flow Total Time Reported ID Type (Inlet)Node Invert Invert Slope Height Roughness Flow Capacity Design Flow Velocity Depth Depth/Surcharged Condition Node Elevation Elevation Ratio Total Depth Ratio (ft)(ft)(ft)(%)(in)(cfs)(cfs)(ft/sec)(ft)(min) 1 Link-02 Pipe CB-FCMH OutPIPE 19.89 14.84 14.70 0.7200 12.000 0.0150 0.54 2.62 0.21 2.76 0.29 0.30 0.00 Calculated 2 PIPE -05 Pipe CB-01 CB-02 300.00 18.36 16.85 0.5000 12.000 0.0090 2.50 3.65 0.68 5.07 0.60 0.61 0.00 Calculated 3 PIPE Pipe MH-01 Stor 4.00 16.04 16.00 0.9800 36.000 0.0090 5.74 11.89 0.48 6.67 0.73 0.49 0.00 Calculated 4 PIPE -19 Pipe CB-02 MH-01 100.54 16.79 16.18 0.6100 18.000 0.0090 1.45 3.91 0.37 4.63 0.42 0.42 0.00 Calculated 5 PIPE -20 Pipe CB-04 CB-02 86.79 18.00 17.50 0.5800 12.000 0.0090 1.21 3.90 0.31 4.41 0.38 0.38 0.00 Calculated 8 Weir-01 Weir Stor CB-FCMH 68.55 14.33 14.33 0.5700 2.500 0.0090 0.00 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Subbasin Hydrology Subbasin : Sub-01 Input Data Area (ac) .....................................................0.86 Peak Rate Factor ........................................484.00 Weighted Curve Number ............................98.00 Rain Gage ID ...............................................Rain Gage-01 Composite Curve Number Area Soil Curve Soil/Surface Description (acres)Group Number -0.86 -98.00 Composite Area & Weighted CN 0.86 98.00 Subbasin Runoff Results Total Rainfall (in) .........................................3.00 Total Runoff (in) ..........................................2.77 Peak Runoff (cfs) ........................................1.51 Weighted Curve Number ............................98.00 Time of Concentration (days hh:mm:ss) .....0 00:02:06 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Subbasin : Sub-01 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Subbasin : Sub-02 Input Data Area (ac) .....................................................1.08 Peak Rate Factor ........................................484.00 Weighted Curve Number ............................98.00 Rain Gage ID ...............................................Rain Gage-01 Composite Curve Number Area Soil Curve Soil/Surface Description (acres)Group Number -1.08 -98.00 Composite Area & Weighted CN 1.08 98.00 Subbasin Runoff Results Total Rainfall (in) .........................................3.00 Total Runoff (in) ..........................................2.77 Peak Runoff (cfs) ........................................1.91 Weighted Curve Number ............................98.00 Time of Concentration (days hh:mm:ss) .....0 00:01:42 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Subbasin : Sub-02 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Subbasin : Sub-03 Input Data Area (ac) .....................................................0.71 Peak Rate Factor ........................................484.00 Weighted Curve Number ............................98.00 Rain Gage ID ...............................................Rain Gage-01 Composite Curve Number Area Soil Curve Soil/Surface Description (acres)Group Number -0.71 -98.00 Composite Area & Weighted CN 0.71 98.00 Subbasin Runoff Results Total Rainfall (in) .........................................3.00 Total Runoff (in) ..........................................2.77 Peak Runoff (cfs) ........................................1.25 Weighted Curve Number ............................98.00 Time of Concentration (days hh:mm:ss) .....0 00:01:48 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Subbasin : Sub-03 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Subbasin : Sub-04 Input Data Area (ac) .....................................................0.80 Peak Rate Factor ........................................484.00 Weighted Curve Number ............................98.00 Rain Gage ID ...............................................Rain Gage-01 Composite Curve Number Area Soil Curve Soil/Surface Description (acres)Group Number -0.80 -98.00 Composite Area & Weighted CN 0.80 98.00 Subbasin Runoff Results Total Rainfall (in) .........................................3.00 Total Runoff (in) ..........................................2.77 Peak Runoff (cfs) ........................................1.41 Weighted Curve Number ............................98.00 Time of Concentration (days hh:mm:ss) .....0 00:02:24 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Subbasin : Sub-04 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Junction Input SN Element Invert Ground/Rim Ground/Rim Initial Initial Surcharge Surcharge Ponded Minimum ID Elevation (Max)(Max)Water Water Elevation Depth Area Pipe Elevation Offset Elevation Depth Cover (ft)(ft)(ft)(ft)(ft)(ft)(ft)(ft²)(in) 1 CB-01 18.36 21.78 3.43 0.00 -18.36 21.78 0.00 200.00 29.12 2 CB-02 16.79 21.78 4.99 0.00 -16.79 21.78 0.00 200.00 39.40 3 CB-03 18.75 21.92 3.17 0.00 -18.75 21.92 0.00 200.00 26.09 4 CB-04 18.00 21.68 3.68 0.00 -18.00 21.68 0.00 200.00 32.21 5 CB-FCMH 14.33 22.84 8.51 0.00 -14.33 22.84 0.00 200.00 0.00 6 MH-01 16.04 22.29 6.25 0.00 -16.04 22.29 0.00 200.00 39.03 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Junction Results SN Element Peak Peak Max HGL Max HGL Max Min Average HGL Average HGL Time of Time of Total Total Time ID Inflow Lateral Elevation Depth Surcharge Freeboard Elevation Depth Max HGL Peak Flooded Flooded Inflow Attained Attained Depth Attained Attained Attained Occurrence Flooding Volume Attained Occurrence (cfs)(cfs)(ft)(ft)(ft)(ft)(ft)(ft)(days hh:mm)(days hh:mm)(ac-in)(min) 1 CB-01 2.53 1.32 18.97 0.61 0.00 2.81 18.49 0.13 0 07:50 0 00:00 0.00 0.00 2 CB-02 5.73 1.88 17.92 1.13 0.00 3.86 17.60 0.81 0 07:50 0 00:00 0.00 0.00 3 CB-03 1.23 1.23 19.14 0.39 0.00 2.79 18.84 0.09 0 07:50 0 00:00 0.00 0.00 4 CB-04 1.47 1.47 18.42 0.42 0.00 3.26 18.10 0.10 0 07:50 0 00:00 0.00 0.00 5 CB-FCMH 5.74 0.00 16.91 0.87 0.00 5.38 16.35 0.31 0 07:50 0 00:00 0.00 0.00 6 MH-01 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Pipe Input SN Element Length Inlet Inlet Outlet Outlet Total Average Pipe Pipe Pipe Manning's Entrance Exit/Bend Additional Initial Flap No. of ID Invert Invert Invert Invert Drop Slope Shape Diameter or Width Roughness Losses Losses Losses Flow Gate Barrels Elevation Offset Elevation Offset Height (ft)(ft)(ft)(ft)(ft)(ft)(%)(in)(in)(cfs) 1 Link-02 19.89 14.84 0.51 14.70 0.00 0.14 0.7200 CIRCULAR 12.000 12.000 0.0150 0.5000 0.5000 0.0000 0.00 No 1 2 PIPE -05 300.00 18.36 0.00 16.85 0.05 1.51 0.5000 CIRCULAR 12.000 12.000 0.0090 0.5000 0.5000 0.0000 0.00 No 1 3 PIPE 4.00 16.04 0.00 16.00 1.67 0.04 0.9800 CIRCULAR 4 PIPE -19 100.54 16.79 0.00 16.18 0.14 0.62 0.6100 CIRCULAR 18.000 18.000 0.0090 0.5000 0.5000 0.0000 0.00 No 1 5 PIPE -20 86.79 18.00 0.00 17.50 0.71 0.50 0.5800 CIRCULAR 12.000 12.000 0.0090 0.5000 0.5000 0.0000 0.00 No 1 6 PIPE -21 68.55 18.75 0.00 18.36 0.00 0.39 0.5700 CIRCULAR 12.000 12.000 0.0090 0.5000 0.5000 0.0000 0.00 No 1 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Pipe Results SN Element Peak Time of Design Flow Peak Flow/Peak Flow Travel Peak Flow Peak Flow Total Time Froude Reported ID Flow Peak Flow Capacity Design Flow Velocity Time Depth Depth/Surcharged Number Condition Occurrence Ratio Total Depth Ratio (cfs)(days hh:mm)(cfs)(ft/sec)(min)(ft)(min) 1 Link-02 0.54 0 00:01 2.62 0.21 2.76 0.12 0.29 0.30 0.00 Calculated 2 PIPE -05 2.50 0 07:51 3.65 0.68 5.07 0.99 0.60 0.61 0.00 Calculated 3 PIPE 5.74 0 07:50 11.89 0.48 6.67 0.25 0.73 0.49 0.00 Calculated 4 PIPE -19 1.45 0 07:50 3.91 0.37 4.63 0.31 0.42 0.42 0.00 Calculated 5 PIPE -20 1.21 0 07:50 3.90 0.31 4.41 0.26 0.38 0.38 0.00 Calculated 6 PIPE -21 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Storage Nodes Storage Node : Stor Input Data 14.33 22.33 8.00 14.33 0.00 60000.00 0.00 Storage Area Volume Curves Storage Curve : Storage-01 Stage Storage Storage Area Volume (ft)(ft²)(ft³) 0 0.0000 0.000 0.1 1158.3168 57.92 0.2 1624.1657 197.04 0.3 1971.9659 376.85 0.4 2256.9677 588.30 0.5 2500.7351 826.19 0.6 2714.4000 1086.95 0.7 2904.6131 1367.90 0.8 3075.7286 1666.92 0.9 3230.7822 1982.25 1 3371.9905 2312.39 1.1 3501.0291 2656.04 1.2 3619.2000 3012.05 1.3 3727.5369 3379.39 1.4 3826.8750 3757.11 1.5 3917.8989 4144.35 1.6 4001.1761 4540.30 1.7 4077.1814 4944.22 1.8 4146.3145 5355.39 1.9 4208.9142 5773.15 2 4265.2681 6196.86 2.1 4315.6209 6625.90 2.2 4360.1806 7059.69 2.3 4399.1232 7497.66 2.4 4432.5966 7939.25 2.5 4460.7242 8383.92 2.6 4483.6063 8831.14 2.7 4501.3232 9280.39 2.8 4513.9355 9731.15 2.9 4521.4860 10182.92 3 4524.0000 10635.19 3.1 4521.4860 11087.46 3.2 4513.9355 11539.23 3.3 4501.3232 11989.99 3.4 4483.6063 12439.24 3.5 4460.7242 12886.46 3.6 4432.5966 13331.13 3.7 4399.1232 13772.72 3.8 4360.1806 14210.69 3.9 4315.6209 14644.48 4 4265.2681 15073.52 4.1 4208.9142 15497.23 4.2 4146.3145 15914.99 4.3 4077.1814 16326.16 4.4 4001.1761 16730.08 4.5 3917.8989 17126.03 4.6 3826.8750 17513.27 4.7 3727.5369 17890.99 4.8 3619.2000 18258.33 4.9 3501.0291 18614.34 5 3371.9905 18957.99 5.1 3230.7822 19288.13 5.2 3075.7286 19603.46 5.3 2904.6131 19902.48 5.4 2714.4000 20183.43 5.5 2500.7351 20444.19 5.6 2256.9677 20682.08 5.7 1971.9659 20893.53 5.8 1624.1657 21073.34 5.9 1158.3168 21212.46 6 0.0000 21270.38 Evaporation Loss ............................................................... Invert Elevation (ft) ............................................................ Max (Rim) Elevation (ft) ..................................................... Max (Rim) Offset (ft) .......................................................... Initial Water Elevation (ft) .................................................. Initial Water Depth (ft) ....................................................... Ponded Area (ft²) ............................................................... DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Storage Node : Stor (continued) Outflow Weirs SN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ft)(ft)(ft)(ft) 1 Weir-01 Rectangular No 17.15 2.82 0.06 2.25 3.33 Outflow Orifices SN Element Orifice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in)(in)(in)(ft) 1 Orifice Bottom CIRCULAR No 2.50 14.33 0.61 Output Summary Results DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Autodesk Storm and Sanitary AnalysisAutodesk Storm and Sanitary AnalysisAutodesk Storm and Sanitary Analysis DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Autodesk Storm and Sanitary AnalysisAutodesk Storm and Sanitary AnalysisAutodesk Storm and Sanitary Analysis DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 28 APPENDIX C : ADDITIONAL PLANS AND REPORTS 1. GEOTECHNICAL ENGINEERING REPORT (FOR REFERENCE ONLY) DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical & Earthquake Engineering Consultants DRAFT GEOTECHNICAL REPORT AND INFILTRATION TEST RESULTS PROPOSED TRUCK PARKING 600 Southwest 10th Street Renton, Washington PROJECT NO. 21-220 June 2021 Prepared for: Elion Partners DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D ________________________________________________ 3213 Eastlake Avenue E, Ste B Seattle, WA 98102 Tel (206) 262-0370 Fax (206) 262-0374 Geotechnical & Earthquake Engineering Consultants June 10, 2021 Project No. 21-220 Mr. Michael Stellino Elion Partners 3323 Northeast 163rd Street, Suite 600 Miami, Florida 33160 Subject: Draft Geotechnical Report and Infiltration Test Results Proposed Truck Parking 600 Southwest 10th Street, Lakewood, Washington Dear Mr. Stellino: Attached please find our draft geotechnical report for the proposed truck parking at 600 Southwest 10th Street in Renton, Washington, Washington. In preparing the attached report, we performed a reconnaissance of the site, observed and logged the excavation of eight test pits, conducted two infiltration tests, and performed our engineering analyses. This report is being provided as a draft pending the results of our laboratory testing. Our final report will be issued the week of June 14 after the laboratory testing is completed, and after we have received review comments from the design team. In summary, based on the results of our study, it is our opinion the proposed truck parking improvements may be constructed as planned. The near surface conditions in the project area consist of fill comprised of poorly graded sand with silt overlying native medium stiff to stiff silt. The fill should provide suitable support for the planned pavement improvements. We conducted two infiltration tests to evaluate the feasibility of infiltrating stormwater at the site. Based on the results of our tests, the site soils have limited infiltration capacity and the suitability of infiltration would be subject to engineering feasibility. We appreciate the opportunity to be of service. Please call if you have any questions. Sincerely, DRAFT Scott D. Dinkelman, LEG Principal Engineering Geologist DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 21-220 600 SW 10th Avenue i PanGEO, Inc. TABLE OF CONTENTS ..................................................................................................................................................... 1 1.0 INTRODUCTION................................................................................................................... 1 2.0 SITE AND PROJECT DESCRIPTION ............................................................................... 1 3.0 SUBSURFACE EXPLORATIONS ....................................................................................... 3 3.1 TEST PIT EXCAVATIONS ......................................................................................................... 3 3.2 LABORATORY TESTING .......................................................................................................... 3 3.2.1 Moisture Content and Grain Size Distribution Analysis ............................................... 3 3.2.2 Cation Exchange Capacity and Organic Content ......................................................... 4 4.0 SUBSURFACE CONDITIONS ............................................................................................. 4 4.1 SITE GEOLOGY ....................................................................................................................... 4 4.2 SOIL CONDITIONS................................................................................................................... 5 4.3 GROUNDWATER CONDITIONS ................................................................................................. 5 5.0 INFILTRATION TESTING AND RECOMMENDATIONS ............................................ 6 5.1 TEST METHOD ........................................................................................................................ 6 5.2 CORRECTION FACTORS .......................................................................................................... 7 5.3 LONG TERM INFILTRATION RATE FOR DESIGN ....................................................................... 7 5.4 CATION EXCHANGE CAPACITY TEST RESULTS ...................................................................... 8 5.5 ORGANIC CONTENT TEST RESULTS ........................................................................................ 9 5.6 CONSTRUCTION CONSIDERATIONS ......................................................................................... 9 6.0 PAVEMENT DESIGN ......................................................................................................... 10 6.1 DESIGN PARAMETERS .......................................................................................................... 10 6.2 PAVEMENT DESIGN .............................................................................................................. 11 6.2.1 Asphalt Pavement Sections .......................................................................................... 11 6.1.3 Portland Cement Concrete Pavements ........................................................................ 12 6.1.4 Subgrade Preparation .................................................................................................. 12 6.1.5 Construction of Cement Treated Base (CTB) .............................................................. 13 6.1.6 Placement of HMA ....................................................................................................... 14 6.1.7 Pavement Surface Drainage ........................................................................................ 14 6.1.8 Maintenance ................................................................................................................. 14 7.0 EARTHWORK CONSIDERATIONS ................................................................................ 14 7.1 TEMPORARY EXCAVATIONS ................................................................................................. 14 7.2 UNDERGROUND UTILITIES ................................................................................................... 15 7.2.1 Pipe Support and Bedding ........................................................................................... 15 7.2.2 Trench Backfill ............................................................................................................. 15 7.4 STRUCTURAL FILL AND COMPACTION .................................................................................. 16 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Street, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue ii PanGEO, Inc. 7.5 MATERIAL REUSE ................................................................................................................ 16 7.6 PERMANENT CUT AND FILL SLOPES ..................................................................................... 17 7.7 WET WEATHER CONSTRUCTION .......................................................................................... 17 7.8 EROSION CONSIDERATIONS .................................................................................................. 17 8.0 LIMITATIONS ..................................................................................................................... 18 9.0 LIST OF REFERENCES ..................................................................................................... 20 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Street, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue iii PanGEO, Inc. LIST OF ATTACHMENTS Figure 1 Vicinity Map Figure 2 Site and Exploration Plan Appendix A Summary Test Pit Logs Figure A-1 Terms and Symbols for Boring and Test Pit Logs Figure A-2 Log of Test Pit TP-1 (Infiltration Test) Figure A-3 Log of Test Pit TP-2 (Infiltration Test) Figure A-4 Log of Test Pit TP-3 Figure A-5 Log of Test Pit TP-4 Figure A-6 Log of Test Pit TP-5 Figure A-7 Log of Test Pit TP-6 Figure A-7 Log of Test Pit TP-7 Figure A-8 Log of Test Pit TP-8 Appendix B Geotechnical Laboratory Test Results Figure B-1 Grain Size Distribution (Results Pending) Appendix C Analytical Laboratory Test Results Cation Exchange Capacity and Organic Matter Test Results (Results Pending) DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 21-220 600 SW 10th Avenue PanGEO, Inc. 1 DRAFT GEOTECHNICAL REPORT AND INFILTRATION ASSESSMENT PROPOSED TRUCK PARKING 600 SOUTHWEST 10TH AVENUE RENTON, WASHINGTON _______________________________________________________________________ 1.0 INTRODUCTION PanGEO has completed a geotechnical study and infiltration assessment for the proposed truck parking at 600 Southwest 10th Avenue in Renton, Washington. Our scope of services included conducting a site reconnaissance, excavating eight test pits, conducting two Small Pilot Infiltration Tests, and developing the conclusions and recommendations presented in this report. This report is being provided in draft form for the preliminary use of the design team, pending the results of our laboratory testing. We will provide a final version of this report when the laboratory testing is completed. However, we do not anticipate the test results to affect the recommendations contained herein. 2.0 SITE AND PROJECT DESCRIPTION The subject site is located at 600 Southwest 10th Avenue in Renton, Washington and is approximately as shown on Figure 1, Vicinity Map. The project site is an approximately rectangular-shaped area on the north side of the existing warehouse building at 600 Southwest 10th Avenue and comprises about 4½ acres. The project area is surrounded to the north, south, east, and west by one-story warehouse buildings. The attached Figure 2, Site and Exploration Plan shows the layout of the site. Plate 1 on the next page provides an aerial view of the site while Plate 2 on the next page provides a ground level view of the site at the time of this study. The site is currently vacant of structures and is flat, with less than five feet of elevation change across the length of the site. The north half of the site is vegetated with a thin covering of grass, while the south portion of the site is surfaced with asphalt and gravel and is being used for outdoor storage. The perimeter of the site is vegetated with alder trees. We understand it is planned to develop the site for use as truck parking with spaces for 140 WB- 40 semi-trucks with trailers along with associated driving and turning lanes. At the time of this study, it had not been determined how many trucks would use the facility on a daily basis. For pavement design purposes, we have assumed 100 truck trips per day. We understand it is planned DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 2 PanGEO, Inc. to use both concrete and asphalt pavements. The planned improvements will also include the installation of underground utilities. Surface water from the impervious surfaces will be directed to an infiltration trench below the central portion of the site. Plate 1: Aerial view of the site looking toward the north. The warehouse at 600 Southwest 10th Street is in the lower portion of the photo. The project area is outlined in yellow. Plate 2: Ground level view of the site. View is looking from west to east. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 3 PanGEO, Inc. 3.0 SUBSURFACE EXPLORATIONS 3.1 TEST PIT EXCAVATIONS Eight test pits (TP-1 through TP-8) were excavated at the site on May 27, 2021. The test pits were excavated using a CAT 305E excavator. The approximate locations of our test pits were identified in the field relative to site features and are shown on Figure 2, Site and Exploration Plan. A geologist from PanGEO was present throughout the infiltration test program to observe the excavation, assist in sampling, and to document the soil samples obtained from the excavation and perform the tests. The relative in-situ density of cohesionless soils, or the relative consistency of fine-grained soils, was estimated from the excavating action of the excavator, probing the sidewalls of the test pits with a ½-inch diameter T-handle probe, and the stability of the test pit sidewalls. Where soil contacts were gradual or undulating, the average depth of the contact was recorded in the log. Test Pits TP-1 and TP-2 were used for infiltration testing purposes. The infiltration testing process consisted of initially excavating to about four feet below grade for testing. After the infiltration tests were completed the test pits were excavated to a maximum depth of about ten feet below grade. Details of our infiltration testing and discussion of the test results are included in Section 5 of this report. The soils were logged in general accordance with ASTM D-2487 Standard Practice for Classification of Soils for Engineering Purposes and the system summarized on Figure A-1, Terms and Symbols for Boring and Test Pit Logs. The summary test pit logs are included in Appendix A. 3.2 LABORATORY TESTING Representative soil samples have been submitted for laboratory testing, to verify or modify the field soil classification and to evaluate the general physical properties and engineering characteristics of the soil encountered. The test results are pending, and will be included in our final report. 3.2.1 Moisture Content and Grain Size Distribution Analysis Moisture content tests and grain-size distribution analysis were performed on six soil samples collected from the test pits. The tests were conducted in general accordance with ASTM D2216 Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 4 PanGEO, Inc. Rock by Mass and ASTM D-6913 Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis. A summary of our test results is included in Appendix B of this report. 3.2.2 Cation Exchange Capacity and Organic Content Four samples were submitted to Kuo Testing Labs for cation exchange capacity (CEC) testing in accordance with EPA Laboratory Method 9081. The CEC is a calculated value that estimates of the soil’s ability to attract, retain, and exchange cation elements. It is reported in millequivalents per 100 grams of soil (meq/100g). The results of the CEC tests are discussed in Section 5.4 of this report and are provided in Appendix C. 3.2.3 Organics Content Testing Four samples were also submitted to Kuo Testing Labs to determine the percent organics content. The testing was performed in general accordance with the ASTM D-2974 Standard Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic Soils. Section 5.5 of this report discusses the organics test results. 4.0 SUBSURFACE CONDITIONS 4.1 SITE GEOLOGY Based on review of the Geologic Map of the Renton Quadrangle, King County, Washington (Mullineaux, 1965) the geologic units in the vicinity of the site consist of Quaternary Alluvium deposited by the Cedar River (Qac) and Quaternary Alluvium deposited by the White River (Qaw). Quaternary Alluvium deposited by the Cedar River consists of sand and gravel deposited with thin interbeds of silt, clay and peat and occurs along the edges of the Duwamish Valley. Quaternary Alluvium deposited by the White River consists of clay, silt, and sand that locally contains peat and gravel. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 5 PanGEO, Inc. 4.2 SOIL CONDITIONS For a detailed description of the subsurface conditions encountered at each exploration location, please refer to our test pit logs provided in Appendix A. The stratigraphic contacts indicated on the logs represent the approximate depth to boundaries between soil units. Actual transitions between soil units may be more gradual or occur at different elevations. The descriptions of groundwater conditions and depths are likewise approximate. The following is a generalized description of the soils encountered in the test pits. Topsoil – A surficial layer of topsoil and sod was encountered at our test pit locations. The topsoil was about six inches thick and consisted of dark brown sand with silt and organics. Fill – Below the topsoil, we encountered fill. The fill ranged from two to four feet thick and consisted of poorly graded fine to medium sand with silt and a trace of gravel. Based on the extent of the fill encountered at our exploration locations, it is likely the pavement subgrade soils will consist of fill. Quaternary Alluvium (Qaw) – Directly below the fill, we encountered medium stiff to stiff gray silt with a trace to some sand. Based on the relatively fined grained nature of this soil, we classified this soil as Quaternary Alluvium deposited by the White River. This soil was encountered to the maximum exploration depth of 10 feet below grade. Our test pits were backfilled after completion of our logging and testing. The backfill was not compacted. We recommend the backfill in the test pits be overexcavated during clearing and grading and backfilled with properly-compacted structural fill. Our subsurface descriptions are based on the conditions encountered at the time of our exploration. Soil conditions between our exploration locations may vary from those encountered. The nature and extent of variations between our exploratory locations may not become evident until construction. If variations do appear, PanGEO should be requested to reevaluate the recommendations in this report and to modify or verify them in writing prior to proceeding with earthwork and construction. 4.3 GROUNDWATER CONDITIONS Light groundwater seepage was encountered at 8 to 8½ feet below grade in all of our test pits except Test Pits TP-4, TP-5, and TP-7 located along the north side of the site. With the planned DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 6 PanGEO, Inc. improvements to be constructed at or near existing site grade, we do not anticipate that groundwater seepage will result in construction related issues. However, groundwater could be encountered in utility trenches, especially deep utilities, if planned. It should also be noted that groundwater elevations may vary depending on the season, local subsurface conditions, and other factors. Groundwater levels are normally highest during the winter and early spring (typically October through May). The planned infiltration systems will need to be set at least five feet above the wet season high groundwater elevation. We installed shallow two-inch diameter standpipe piezometers in Test Pits TP-4, TP-6, and TP-7 to allow for monitoring of groundwater levels during the wet season to allow for establishing the wet season high groundwater elevation. 5.0 INFILTRATION TESTING AND RECOMMENDATIONS Two infiltration tests were conducted in TP-1 and TP-2 at the locations indicated on the attached Figure 2. The test method and the results are discussed below. 5.1 TEST METHOD The field infiltration tests were conducted in general accordance with the procedure for Small Pilot Infiltration Test (PIT) as outlined in the King County Surface Water Design Manual (KCSWDM) (King County, 2016). In general, the test consisted of the following procedure: • A test pit was excavated to the approximate design bottom of the proposed infiltration facilities with a minimum bottom area of 12 square feet. • The test pit was pre-soaked by maintaining a water level of at least 12 inches above the bottom of the pit. • After the pre-soak period, an electronic flow meter was used to monitor the amount of water needed to maintain a constant head of 12 inches for at least one hour and until at least a constant volume of water per time unit was achieved. • At the end of the constant head test, we measured the falling head infiltration rate by shutting off the water flow and recorded the drop in water level over regular time intervals for one hour or until all of the water was completely infiltrated. The field infiltration rate was calculated based on the final measured volume per time unit, and the surface area of the holes. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 7 PanGEO, Inc. 5.2 CORRECTION FACTORS The KCSWDM requires the infiltration rates measured in the field be reduced by applying correction factors to account for uncertainties in the test method used, depth to the water table or impervious strata, the geometry of the infiltration facility, and degree of influent control to prevent siltation and bio-buildup. We used the simplified method outlined in the King County Surface Water Design Manual (KCSWDM, 2016) to estimate the maximum design infiltration rate. The simplified method equation is provided below: Idesign = Imeasured x Ftesting x Fgeometry x Fplugging (KCSWDM Eq 5-11) where, Fgeometry = 4 D/W + 0.05 (KCSWDM Eq 5-12) (where D = the depth from the bottom of the proposed facility to the maximum wet-season water table or nearest impervious layer, whichever is less, and W = width of the facility, a value between 0.25 and 1.0 should be used) The following values were used to reduce the field infiltration rate and provide a long-term design infiltration rate: Ftesting = 0.5 for large-scale testing Fgeometry = 1.0 (D=4 feet*, W=4 feet) Fplugging = 0.7 (loams and sandy loams) *To determine Fgeometry, we estimated D to be 4 feet based on an assumed infiltration system depth of four feet and used a groundwater elevation of eight feet below grade. 5.3 LONG TERM INFILTRATION RATE FOR DESIGN Table 1, below, details the infiltration data collected during the tests and the long-term design rates calculated for each tested location. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 8 PanGEO, Inc. TABLE 1: Small Pilot Infiltration Test Data Corrected for Long Term Design Rate Test Location (depth) Pre-Soak Duration (hours) Test Stage Test Duration Field Measured Rate (in/hour) Correction Factors Long Term Design Rate (in/hour) Ftesting Fgeometry Fplugging TP-1 (4 feet) 6 Constant Head 1 hour 0.7 0.5 1 0.7 0.25 TP-2 (4 feet) 6 Constant Head 1 hour 0.4 0.5 1 0.7 0.14 Infiltration provided in Table 2 are relatively low and the soils may not be feasible to use for infiltration. The KCSWDM does not specify a minimum infiltration rate for infiltration system design except a requirement that any ponding be drawn down with 24 hours. The infiltration system feasibility should be determined by the civil engineer. 5.4 CATION EXCHANGE CAPACITY TEST RESULTS The KCSWDM specifies that soils used for treatment and infiltration should have a CEC of greater than or equal to 5 milliequivalents per 100 grams of dry soil (meq/100g). CEC testing was performed on two representative samples from our test pits. Table 2, below, provides a summary of the CEC test results. TABLE 2: Cation Exchange Capacity Test Results Location Soil Sample Depth (feet) CEC (meq/100g) TP-1 4 PENDING TP-2 4 PENDING The results of the analytical testing are provided in Appendix C. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 9 PanGEO, Inc. 5.5 ORGANIC CONTENT TEST RESULTS Two representative samples collected from our infiltration test pits were submitted to determine the percent of organic material in the soils at our infiltration test locations. The testing procedure was performed in general accordance with the ASTM D2974-13 Standard Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic Soils. Table 5, below, provides a summary of the organic material test results. TABLE 3: Organic Matter of Organic Soils Test Results Location Soil Sample Depth (feet) Organic Content (%) PIT-1 4 PENDING PIT-2 4 PENDING A summary of the analytical testing is provided in Appendix C. 5.6 CONSTRUCTION CONSIDERATIONS Infiltration facilities are post-construction facilities which are designed to improve the quality and manage the volume of stormwater runoff by encouraging natural infiltration on-site. In order to protect the infiltration receptor soils from becoming clogged with sediment and/or becoming compacted during construction, we recommend the following measures be implemented during construction: • The infiltration facilities should be constructed as late in the schedule as feasible and should not be constructed until after the upstream areas are stabilized. • Heavy equipment traffic on prepared subgrades should be limited, especially during wet weather. • If fine grained sediment is deposited or tracked onto the infiltration system subgrade, it should be removed using an excavator with a grade plate, a small dozer or a vacuum truck. • The subgrade should be scarified prior to placing fill to prevent sealing of the receptor soils. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 10 PanGEO, Inc. • Structural fill and aggregate base materials should be end-dumped at the edge of the fill area and the material pushed out over the subgrade. • Grading of the infiltration galleries should be accomplished using low-impact earth- moving equipment to prevent compaction of the underlying soils. Wide tracked vehicles such as excavator, small dozers and bobcats are suggested. • The infiltration system subgrade soils should be reviewed after excavation to verify the soils encountered are as anticipated. • The infiltration system should not be brought on-line until after earthwork is completed and the site is permanently stabilized with vegetation and hardscaping. 6.0 PAVEMENT DESIGN 6.1 DESIGN PARAMETERS Our pavement analysis was performed using the 1993 AASHTO pavement design methodology. Our analysis included evaluating hot mix asphalt (HMA) and Portland Cement Concrete (PCC) pavement sections. For the HMA pavement section, it is our opinion that the HMA may be used in conjunction with crushed surfacing base course (i.e., 1 ¼ inch minus crushed rock), or cement treated base. The principal benefit of CTB is the use of on-site soils and the reduction and possible elimination of the need for crushed rock base for pavement. We understand traffic will consist of 40-WB semi-trucks with trailers. The number of daily truck trips was not available at the time this study was prepared. Therefore, for our design we assumed 100 trucks per day. The parameters summarized in Table 4 on the next page were used in our design. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 11 PanGEO, Inc. TABLE 4: Pavement Design Parameters Parameter Value HMA PCC Pavement Design life 20 years 20 years Reliability 85% 85% Overall Standard Deviation 0.45 0.45 Initial Serviceability 4.2 4.2 Terminal Serviceability 2.5 2.5 Design Serviceability Loss (∆PSI) 1.7 1.7 Drainage Coefficient 1.0 1.0 Layer Coefficients: Hot Mix Asphalt Crushed Surfacing Base/Top Course Cement Treated Base 0.44 0.14 0.14 0.11 0.11 Design Resilient Modulus for Subgrade 15,000 psi 15,000 psi Average Annual Daily Traffic 100 100 Percent Heavy Trucks 100 100 ESAL 1,145,000 1,145,000 The performance of the pavement designs provided below and using the design period assumed in our analysis would depend on a number of factors, including the actual traffic loading conditions and performance of regular maintenance. The recommended pavement sections will need to be revised if the anticipated truck traffic varies from our assumptions. 6.2 PAVEMENT DESIGN 6.2.1 Asphalt Pavement Sections We recommend the following minimum pavement sections be used in new asphalt paved areas: Light Traffic Areas – truck parking areas and passenger vehicle areas: • Three inches of Class ½ inch Hot Mix Asphalt (HMA) over six inches crushed surfacing top/base course (CSTC/CSBC); or DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 12 PanGEO, Inc. • Three inches of Class ½ inch HMA over 12 inches cement treated base (see detailed discussion on cement treated base in Section 6.5.1) Heavy Traffic Areas – drive aisles subjected to truck traffic: • Four inches of Class ½ inch Hot Mix Asphalt (HMA) over six inches crushed surfacing top/base course (CSTC/CSBC); or • Four inches of Class ½ inch HMA over 12 inches cement treated base The asphalt binder should consist of pavement grade (PG) PG64-22. 6.1.3 Portland Cement Concrete Pavements • Eight inches of Portland cement concrete (plain butt jointed) over six inches of crushed surfacing base course; or • Eight inches of Portland cement concrete (plain butt jointed) over 12 inches of cement treated base. The design is based on using concrete that will achieve a minimum 28-day compressive strength (f’c) of 4,000 psi. The transverse joints in the pavement should be spaced 15 feet apart or less and should be in accordance with WSDOT Standard Specifications for Road, Bridge and Municipal Construction (WSDOT, 2021). 6.1.4 Subgrade Preparation Based on the conditions encountered in our test pits, the pavement subgrade will consist of existing fill comprised of poorly graded sand with silt and a trace of gravel. Site preparation for new pavement areas should begin with removal of the existing topsoil, vegetation, roots, debris, deleterious material, and unsuitable soil from the area of the proposed improvements and excavating to the design subgrade elevation, where applicable. Following the stripping operation and excavations necessary to achieve construction subgrade elevations, the ground surface where structural fill, or pavements are to be placed should be observed by PanGEO. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 13 PanGEO, Inc. The test pits for this study were backfilled with the site soils after completion of our logging and testing. The backfill was not compacted to the requirements of structural fill. The test pit locations should be identified during grading and the fill overexcavated and backfilled with properly- compacted structural fill. Proofrolling should be performed to identify soft or unstable areas. Soft or yielding areas identified during proofrolling should be moisture conditioned as needed and re-compacted in place. If the soft areas are still yielding after re-compaction, they should be overexcavated and replaced with structural fill to a depth that will provide a stable pavement base. The optional use of a geotextile subgrade stabilization fabric, such as Mirafi 600X, or an equivalent product placed directly on the overexcavated surface may help to bridge excessively unstable areas. The need for geotextile can be determined during construction, based on the actual conditions encountered, but should be included in the construction budget. Overexcavated areas should be backfilled with WSDOT 9-03.9(3) Crushed Surfacing Base Course, or WSDOT 9-03.14 (1) Gravel Borrow (WSDOT, 2021) compacted to the requirements of structural fill. The subgrade preparation should be observed by PanGEO during construction, to verify the adequacy of the prepared subgrade. 6.1.5 Construction of Cement Treated Base (CTB) If cement treated base pavement option is used, the cement treatment should be performed using Portland concrete cement. The cement should be applied at a rate of at least 10 pounds of cement per square foot of area to be treated to a depth of 12 inches. The cement treatment operation should be performed in general accordance with the following recommendations: • For every square foot of treated area, mix minimum 10 pounds of cement into the upper 12 inches of the subgrade soils. A road reclaimer/stabilizer, or similar piece of equipment, should be used to thoroughly mix the cement into the soil to the recommended treatment depth. • The treated subgrade should then be graded and compacted using a smooth-drum vibratory roller to at least 95 percent maximum dry density in accordance with ASTM D 1557, Modified Proctor. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 14 PanGEO, Inc. • Heavy truck traffic should be kept off the treated area for at least 3 days after treatment to allow the cement treated soils to cure; passenger vehicles may use the CTB treated surface two hours after its completion. 6.1.6 Placement of HMA Placement of HMA should be in accordance with Section 5-04 of the WSDOT Standard Specifications for Road and Bridge Construction (WSDOT, 2021). 6.1.7 Pavement Surface Drainage The pavement surface should be sloped to provide drainage of surface water to the storm drain system. Wherever possible, the grades around the perimeter of the parking log should be sloped so surface water will drain away from the pavement. Water that ponds on or adjacent to pavement surfaces could penetrate or seep under the pavement, saturate the subgrade and contribute to premature pavement deterioration. 6.1.8 Maintenance Cracking in asphalt pavement is typical and should be expected over the life of the pavement. These require routine maintenance to prevent accelerated deterioration. Accordingly, it is highly recommended to establish a maintenance program where the cracks are routinely filled as they appear beginning at about the second year of life. It is also recommended that surface fog seal coats be considered beginning at about year five and every five years after. This will help preserve the pavements, extending the pavement service life. It should be anticipated that a functional overlay will be required at between 20 and 30 years. 7.0 EARTHWORK CONSIDERATIONS 7.1 TEMPORARY EXCAVATIONS Temporary excavations should be made in accordance with Part N of WAC (Washington Administrative Code) 296-155. The contractor is responsible for maintaining safe excavation slopes and/or shoring. It is contractor’s responsibility to maintain safe working conditions, including temporary excavation stability and, if needed, dewatering. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 15 PanGEO, Inc. Based on the encountered fill and fine grained soils underlying the project area, temporary excavations should be inclined no steeper and 1½H:1V (Horizontal:Vertical). Temporary excavations should be evaluated in the field during construction based on actual observed soil conditions. If seepage is encountered, temporary excavation slope inclinations may need to be reduced. During wet weather, the cut slopes may need to be flattened to reduce potential erosion or should be covered with plastic sheeting. 7.2 UNDERGROUND UTILITIES Underground utilities planned as part of the road improvements can be installed using conventional excavation methods. Excavations in excess of 4 feet in depth should be sloped in accordance with the recommendations in Section 8.2 of this study. 7.2.1 Pipe Support and Bedding Utility installation should be conducted in accordance with the 2021 WSDOT Standard Specifications or other applicable specifications for placement and compaction of pipe bedding and backfill. In general, pipe bedding should be placed in loose lifts not exceeding 6 inches in thickness and compacted to a firm and unyielding condition. Bedding materials and thicknesses provided should be suitable for the utility system and materials installed, and in accordance with any applicable manufacturers' recommendations. Pipe bedding materials should be placed on relatively undisturbed native soil. Based on our field explorations, we anticipate relatively coarse-grained soils comprised of poorly graded gravel with cobbles. Some overexcavation and removal of cobbles should be anticipated at the pipe invert elevation to maintain a uniform grade for the utility installation. Where overexcavation is needed, additional pipe bedding should be placed to restore the grade. 7.2.2 Trench Backfill Utility trench backfill is a primary concern in reducing the potential for settlement along utility alignments, particularly in pavement areas. It is important that each section of utility line be adequately supported in the bedding material. The material should be hand tamped to ensure support is provided around the pipe haunches. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 16 PanGEO, Inc. Fill should be carefully placed and hand tamped to about 12 inches above the crown of the pipe before heavy compaction equipment is brought into use. The trench backfill should be placed in 8- to 12-inch-thick loose lifts and compacted to at least 95 percent maximum dry density, per ASTM D1557 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort. In order to reduce the potential for damaging the utilities, heavy compaction equipment should not be permitted to operate directly over utilities until a minimum of two feet of backfill has been placed. 7.4 STRUCTURAL FILL AND COMPACTION Structural fill should be properly moisture conditioned, placed in loose, horizontal lifts less than 8 inches in thickness, and compacted to at least 95 percent maximum density, determined using ASTM D 1557 (Modified Proctor). The procedure to achieve proper density of a compacted fill depends on the size and type of compacting equipment, the number of passes, thickness of the lifts being compacted, and certain soil properties. If the excavation is constricted and limits the use of heavy equipment, smaller equipment can be used, but the lift thickness will need to be reduced to achieve the required relative compaction. Generally, loosely compacted soils are a result of poor construction technique or improper moisture content. Soils with high fines contents are particularly susceptible to becoming too wet and coarse-grained materials easily become too dry, for proper compaction. Silty or clayey soils with a moisture content too high for adequate compaction should be dried as necessary, or moisture conditioned by mixing with drier materials, or other methods. 7.5 MATERIAL REUSE The existing fill may be used as structural fill, provided earthwork is conducted during dry weather and the fill is free of topsoil and organics. If it is planned to use the existing fill as structural fill the excavated soil should be stockpiled and protected with plastic sheeting to prevent it from becoming saturated by precipitation or runoff. The native silt underlying the site will not be suitable for reuse as structural fill due to the high percent of fines and relatively high natural moisture content. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 17 PanGEO, Inc. 7.6 PERMANENT CUT AND FILL SLOPES Based on the anticipated soil that will be exposed in the planned excavation, we recommend permanent cut and fill slopes be constructed no steeper than 2H:1V (Horizontal:Vertical). Cut slopes should be observed by a qualified professional during excavation to verify that conditions are as anticipated. Supplementary recommendations can then be developed, if needed, to improve stability, including flattening of slopes or installation of surface or subsurface drains. Permanently exposed slopes should be seeded with an appropriate species of vegetation to reduce erosion and improve stability of the surficial layer of soil. 7.7 WET WEATHER CONSTRUCTION General recommendations relative to earthwork performed in wet weather or in wet conditions are presented below. The following procedures are best management practices recommended for use in wet weather construction: • Earthwork should be performed in small areas to minimize subgrade exposure to wet weather. Excavation or the removal of unsuitable soil should be followed promptly by the placement and compaction of clean structural fill. The size and type of construction equipment used may have to be limited to prevent soil disturbance. • During wet weather, the allowable fines content of the structural fill should be reduced to no more than 5 percent by weight based on the portion passing the 0.75-inch sieve. The fines should be non-plastic. • The ground surface within the construction area should be graded to promote run-off of surface water and to prevent the ponding of water. • Bales of straw and/or geotextile silt fences should be installed at strategic locations around the site to control erosion and the movement of soil. • Excavation slopes and soils stockpiled on site should be covered with plastic sheeting. 7.8 EROSION CONSIDERATIONS Surface water runoff can be controlled during construction by careful grading practices. Typically, this includes the construction of shallow, upgrade perimeter ditches or low earthen berms in DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 18 PanGEO, Inc. conjunction with silt fences to collect runoff and prevent water from entering excavations or to prevent runoff from the construction area leaving the immediate work site. Temporary erosion control may require the use of hay bales on the downhill side of the project to prevent water from leaving the site and potential storm water detention to trap sand and silt before the water is discharged to a suitable outlet. All collected water should be directed under control to a positive and permanent discharge system. Permanent control of surface water should be incorporated in the final grading design. Adequate surface gradients and drainage systems should be incorporated into the design such that surface runoff is collected and directed away from the reservoir structure to a suitable outlet. Potential issues associated with erosion may also be reduced by establishing vegetation within disturbed areas immediately following grading operations. 8.0 LIMITATIONS We have prepared this report for Elion Partners and the project design team. Recommendations contained in this report are based on a site reconnaissance, a subsurface exploration program, review of pertinent subsurface information, and our understanding of the project. The study was performed using a mutually agreed-upon scope of work. Variations in soil conditions may exist between the locations of the explorations and the actual conditions underlying the site. The nature and extent of soil variations may not be evident until construction occurs. If any soil conditions are encountered at the site that are different from those described in this report, we should be notified immediately to review the applicability of our recommendations. Additionally, we should also be notified to review the applicability of our recommendations if there are any changes in the project scope. The scope of our work does not include services related to construction safety precautions. Our recommendations are not intended to direct the contractors’ methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. Additionally, the scope of our work specifically excludes the assessment of environmental characteristics, particularly those involving hazardous substances. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 19 PanGEO, Inc. This report has been prepared for planning and design purposes for specific application to the proposed project in accordance with the generally accepted standards of local practice at the time this report was written. No warranty, express or implied, is made. This report may be used only by the client and for the purposes stated, within a reasonable time from its issuance. Land use, site conditions (both off and on-site), or other factors including advances in our understanding of applied science, may change over time and could materially affect our findings. Therefore, this report should not be relied upon after 24 months from its issuance. PanGEO should be notified if the project is delayed by more than 24 months from the date of this report so that we may review the applicability of our conclusions considering the time lapse. It is the client’s responsibility to see that all parties to this project, including the designer, contractor, subcontractors, etc., are made aware of this report in its entirety. The use of information contained in this report for bidding purposes should be done at the contractor’s option and risk. Any party other than the client who wishes to use this report shall notify PanGEO of such intended use and for permission to copy this report. Based on the intended use of the report, PanGEO may require that additional work be performed and that an updated report be reissued. Noncompliance with any of these requirements will release PanGEO from any liability resulting from the use this report. We appreciate the opportunity to be of service. Sincerely, DRAFT DRAFT Scott D. Dinkelman, LEG Siew L. Tan, P. E. Principal Engineering Geologist Principal Geotechnical Engineer SDinkelman@pangeoinc.com STan@pangeoinc.com DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Geotechnical Report and Infiltration Assessment Proposed Truck Parking: 600 Southwest 10th Avenue, Renton, Washington June 10, 2021 21-220 600 SW 10th Avenue Page 20 PanGEO, Inc. 9.0 LIST OF REFERENCES Mullineaux, D.R., 1965, Geologic Map of the Renton Quadrangle, King County, Washington: U.S. Geological Survey, Geologic Quadrangle Map GQ-405, scale 1:24000. King County, 2016, King County Surface Water Design Manual, Department of Natural Resources and Parks. WSDOT, 2021, Standard Specifications for Road, Bridge and Municipal Construction, M 41-10. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D VICINITY MAP 21-220 1 Reference: ArcGIS Online Terrain Map Not to Scale PROJECT SITE Proposed Truck Parking 600 Southwest 10th Avenue Renton, WA DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Project No.Figure No. SITE AND EXPLORATION PLAN 21-220 213 - 0 1 1 _ F i g 2 S i t e & E x p l o r a t i o n P l a n . g r f 6 / 1 0 / 2 1 J C R LEGEND: Approx. Scale (feet) Project Boundary 0 200 400 NORTH SOUTHW E S T 1 0 T H S T R E E T Existing Structures SENECA AVE TP-1 (2') TP-2 (2') TP-3 (4') TP-4 (2') TP-5 (2.5')TP-7 (2.5') TP-6 (2') TP-8 (2') TP-1 Approximate Test Pit Location, PanGEO, Inc., May 2021 (Approximate Fill Thickness in Feet) - Infiltration tests were conducted in TP-1 and TP-2 - Ellipse around symbol indicates shallow standpipe piezometer location Proposed Truck Parking 600 Southwest 10th Avenue Renton, WA Proposed Infiltration System DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D APPENDIX A SUMMARY TEST PIT LOGS DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D MOISTURE CONTENT 2-inch OD Split Spoon, SPT (140-lb. hammer, 30" drop) 3.25-inch OD Spilt Spoon (300-lb hammer, 30" drop) Non-standard penetration test (see boring log for details) Thin wall (Shelby) tube Grab Rock core Vane Shear Dusty, dry to the touch Damp but no visible water Visible free water Terms and Symbols for Boring and Test Pit Logs Density SILT / CLAY GRAVEL (<5% fines) GRAVEL (>12% fines) SAND (<5% fines) SAND (>12% fines) Liquid Limit < 50 Liquid Limit > 50 Breaks along defined planes Fracture planes that are polished or glossy Angular soil lumps that resist breakdown Soil that is broken and mixed Less than one per foot More than one per foot Angle between bedding plane and a planenormaltocoreaxis Very Loose Loose Med. Dense Dense Very Dense SPT N-values Approx. Undrained Shear Strength (psf) <4 4 to 10 10 to 30 30 to 50 >50 <2 2 to 4 4 to 8 8 to 15 15 to 30 >30 SPT N-values Units of material distinguished by color and/orcomposition frommaterial unitsabove andbelow Layers of soil typically 0.05 to 1mm thick, max. 1 cm Layer of soil that pinches out laterally Alternating layers of differing soil material Erratic, discontinuous deposit of limited extent Soil with uniform color and composition throughout Approx. Relative Density (%) Gravel Layered: Laminated: Lens: Interlayered: Pocket: Homogeneous: Highly Organic Soils #4 to #10 sieve (4.5 to 2.0 mm) #10 to #40 sieve (2.0 to 0.42 mm) #40 to #200 sieve (0.42 to 0.074 mm) 0.074 to 0.002 mm <0.002 mm UNIFIED SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS GROUP DESCRIPTIONS Notes: MONITORING WELL <15 15 - 35 35 - 65 65 - 85 85 - 100 GW GP GM GC SW SP SM SC ML CL OL MH CH OH PT TEST SYMBOLS 50%or more passing #200 sieve Groundwater Level at time of drilling (ATD)Static Groundwater Level Cement / Concrete Seal Bentonite grout / seal Silica sand backfill Slotted tip Slough <250 250 - 500 500 - 1000 1000 - 2000 2000 - 4000 >4000 RELATIVE DENSITY / CONSISTENCY Fissured: Slickensided: Blocky: Disrupted: Scattered: Numerous: BCN: COMPONENT DEFINITIONS Dry Moist Wet 1. Soil exploration logs contain material descriptions based on visual observation and field tests using a systemmodified from the Uniform Soil Classification System (USCS). Where necessary laboratory tests have beenconducted (as noted in the "Other Tests" column), unit descriptions may include a classification. Please refer to thediscussions in the report text for a more complete description of the subsurface conditions. 2. The graphic symbols given above are not inclusive of all symbols that may appear on the borehole logs.Other symbols may be used where field observations indicated mixed soil constituents or dual constituent materials. COMPONENT SIZE / SIEVE RANGE COMPONENT SIZE / SIEVE RANGE SYMBOLS Sample/In Situ test types and intervals Silt and Clay Consistency SAND / GRAVEL Very Soft Soft Med. Stiff Stiff Very Stiff Hard Phone: 206.262.0370 Bottom of BoringBoulder: Cobbles: Gravel Coarse Gravel: Fine Gravel: Sand Coarse Sand: Medium Sand: Fine Sand: Silt Clay > 12 inches 3 to 12 inches 3 to 3/4 inches 3/4 inches to #4 sieve Atterberg Limit Test Compaction Tests Consolidation Dry Density Direct Shear Fines Content Grain Size Permeability Pocket Penetrometer R-value Specific Gravity Torvane Triaxial Compression Unconfined Compression Sand 50% or more of the coarse fraction passing the #4 sieve. Use dual symbols (eg. SP-SM) for 5% to 12% fines. for In Situ and Laboratory Testslisted in "Other Tests" column. 50% or more of the coarse fraction retained on the #4 sieve. Use dual symbols (eg. GP-GM) for 5% to 12% fines. DESCRIPTIONS OF SOIL STRUCTURES Well-graded GRAVEL Poorly-graded GRAVEL Silty GRAVEL Clayey GRAVEL Well-graded SAND Poorly-graded SAND Silty SAND Clayey SAND SILT Lean CLAY Organic SILT or CLAY Elastic SILT Fat CLAY Organic SILT or CLAY PEAT ATT Comp Con DD DS %F GS Perm PP R SG TV TXC UCC LO G KE Y 09 - 1 1 8 LO G . G P J P A N G E O . G D T 11 /12 /1 3 Figure A-1 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Test Pit TP-1 (Infiltration Test) Location: 47.471510, -122.225836 (WGS84) Approximate ground surface elevation: 23 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil) ½ – 2 Loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2 – 10 Medium stiff to stiff, gray to brown, SILT, trace to some sand, trace clay, minor iron-oxide staining; moist to wet (Alluvium) Image of soils encountered at approximately 4 feet (testing depth). After testing, the test pit was excavated to approximately 10 feet below the existing ground surface. Light groundwater seepage was encountered at approximately 8 feet at the time of exploration. Figure A-2 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Test Pit TP-2 (Infiltration Test) Location: 47.471547, -122.226891 (WGS84) Approximate ground surface elevation: 22 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 2 Loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2 – 10 Medium stiff to stiff, gray, SILT, trace to some sand, trace clay, minor iron-oxide staining; moist to wet (Alluvium) Image of soils encountered at approximately 4 feet (testing depth). After testing, the test pit was excavated to approximately 10 feet below the existing ground surface. Light groundwater seepage was encountered at approximately 8 feet at the time of exploration. Figure A-3 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Test Pit TP-3 Location: 47.471558, -122.227340 (WGS84) Approximate ground surface elevation: 22 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 4 Loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 4 – 10 Medium stiff to stiff, gray, SILT, trace to some sand, trace clay, trace organic material (wood), minor iron-oxide staining; moist to wet (Alluvium) - Wood debris encountered between approximately 6 and 8 feet. Image of soils encountered approximately 10 feet below the existing ground surface. Light groundwater seepage was encountered at approximately 8 feet at the time of exploration. Figure A-4 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Test Pit TP-4 Location: 47.471783, -122.227372 (WGS84) Approximate ground surface elevation: 22 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 2 Loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2 – 10 Medium stiff to stiff, gray, clayey SILT to silty CLAY, trace to some sand, minor iron-oxide staining; moist to very moist (Alluvium) Image of soils encountered approximately 10 feet below the existing ground surface. Groundwater was not encountered at the time of exploration. However, an increase in moisture was noted below approximately 8 feet. Figure A-5 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Test Pit TP-5 Location: 47.471793, -122.226299 (WGS84) Approximate ground surface elevation: 23 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 2½ Topsoil over loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2½– 10 Medium stiff to stiff, brown to gray, SILT, trace to some sand, trace clay, minor iron-oxide staining; moist to very moist (Alluvium) Image of soils encountered approximately 10 feet below the existing ground surface. Groundwater was not encountered at the time of exploration. Figure A-6 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Test Pit TP-6 Location: 47.471551, -122.226204 (WGS84) Approximate ground surface elevation: 22 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 2 Topsoil over loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2 – 10 Medium stiff to stiff, gray, SILT, trace to some sand, trace to some clay, minor iron-oxide staining; moist to wet (Alluvium) - Transitions to SAND with silt and clay at approximately 6 feet. Image of soils encountered approximately 10 feet below the existing ground surface. Light groundwater seepage was observed at approximately 8½ feet at the time of exploration. Figure A-7 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Test Pit TP-7 Location: 47.471761, -122.224953 (WGS84) Approximate ground surface elevation: 24 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 2½ Loose to medium dense, brown, fine to medium SAND with silt, trace gravel, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2½ – 10 Medium stiff to stiff, brown to gray, SILT, trace to some sand, trace clay, minor iron-oxide staining; moist to very moist (Alluvium) Image of soils encountered approximately 10 feet below the existing ground surface. Groundwater was not encountered at the time of exploration. Figure A-8 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Test Pit TP-8 Location: 47.471200, -122.225226 (WGS84) Approximate ground surface elevation: 22 feet (NAVD88) Depth (ft) Material Description 0 – ½ Sod with loose fine to medium SAND with organics (Topsoil and Sod) ½ – 2½ Loose to medium dense, brown, gravelly fine to medium SAND with silt, trace organic material (rootlets), minor iron-oxide staining; moist (Fill) 2½ – 10 Medium stiff to stiff, gray, SILT, trace to some sand, trace clay, minor iron-oxide staining; moist to wet (Alluvium) - Sand lens (1½-feet) observed at approximately 8 feet Image of soils encountered approximately 10 feet below the existing ground surface. Light groundwater seepage encountered at approximately 8 feet at the time of exploration. Test Pit Explorations: Test pits were excavated on May 27, 2021 using a CAT 305.5E2 rubber tracked excavator. Test Pits Logged by: Christian Venturino Figure A-9 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D APPENDIX B GEOTECHNICAL LABORATORY TEST RESULTS (RESULTS PENDING) DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D APPENDIX C ANALYTICAL LABORATORY TEST RESULTS (RESULTS PENDING) DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 600 SW 10th Street – Parking Lot Kimley-Horn and Associates, Inc. King County, WA Preliminary Stormwater Report October 31, 2023 Page 29 2. NRCS WEB SOIL SURVEY DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for King County Area, Washington 600 SW 10th Street - Web Soil Survey Natural Resources Conservation Service June 11, 2021 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................11 Map Unit Descriptions.........................................................................................11 King County Area, Washington.......................................................................13 Ur—Urban land...........................................................................................13 References............................................................................................................14 4 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and Custom Soil Resource Report 6 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. Custom Soil Resource Report 7 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D 9 Custom Soil Resource Report Soil Map 52 5 7 6 2 0 52 5 7 6 8 0 52 5 7 7 4 0 52 5 7 8 0 0 52 5 7 8 6 0 52 5 7 9 2 0 52 5 7 9 8 0 52 5 7 6 2 0 52 5 7 6 8 0 52 5 7 7 4 0 52 5 7 8 0 0 52 5 7 8 6 0 52 5 7 9 2 0 52 5 7 9 8 0 558060 558120 558180 558240 558300 558360 558420 558480 558540 558600 558060 558120 558180 558240 558300 558360 558420 558480 558540 558600 47° 28' 21'' N 12 2 ° 1 3 ' 4 7 ' ' W 47° 28' 21'' N 12 2 ° 1 3 ' 1 9 ' ' W 47° 28' 9'' N 12 2 ° 1 3 ' 4 7 ' ' W 47° 28' 9'' N 12 2 ° 1 3 ' 1 9 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 100 200 400 600 Feet 0 35 70 140 210 Meters Map Scale: 1:2,670 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 16, Jun 4, 2020 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 6, 2020—Jul 20, 2020 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 10 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI Ur Urban land 33.7 100.0% Totals for Area of Interest 33.7 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. Custom Soil Resource Report 11 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 12 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D King County Area, Washington Ur—Urban land Map Unit Composition Urban land:100 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Urban Land Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 8 Hydric soil rating: No Custom Soil Resource Report 13 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 14 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report 15 DocuSign Envelope ID: 7DBCA7C0-8C41-4D51-AF13-689B38E87E3D