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34-Drainage Report
Civil Engineers ● Structural Engineers ● Landscape Architects ● Community Planners ● Land Surveyors Technical Information Report PREPARED FOR: BRIC Architecture Inc. 1233 NW Northrup Street, Suite 100 Portland, OR 97209 PROJECT: New Renton High School 400 South 2nd Street Renton, WA 98057 Project No. 2230388.10 PREPARED BY: Brian Schend, PE Senior Engineer REVIEWED BY: William J. Fierst, PE Principal DATE: September 2025 Technical Information Report PREPARED FOR: BRIC Architecture Inc. 1233 NW Northrup Street, Suite 100 Portland, OR 97209 PROJECT: New Renton High School 400 South 2nd Street Renton, WA 98057 Project No. 2230388.10 PREPARED BY: Brian Schend, PE Senior Engineer REVIEWED BY: William J. Fierst, PE Principal DATE: September 2025 I hereby state that this Technical Information Report for the New Renton High School project has been prepared by me or under my supervision and meets the standard of care and expertise that is usual and customary in this community for professional engineers. I understand that City of Renton does not and will not assume liability for the sufficiency, suitability, or performance of drainage facilities prepared by me. 09/12/2025 Technical Information Report New Renton High School Project No. 2230388.10 Table of Contents Section Page 1.0 Project Overview ............................................................................................................................ 1 2.0 Conditions and Requirements Summary .................................................................................... 3 2.1 CR 1 – Discharge at the Natural Location .......................................................................... 3 2.2 CR 2 – Offsite Analysis ....................................................................................................... 3 2.3 CR 3 – Flow Control ............................................................................................................ 3 2.4 CR 4 – Conveyance System ............................................................................................... 4 2.5 CR 5 – Erosion and Sediment Control ................................................................................ 4 2.6 CR 6 – Maintenance and Operations.................................................................................. 4 2.7 CR 7 – Financial Guarantees and Liability ......................................................................... 4 2.8 CR 8 – Water Quality .......................................................................................................... 4 2.9 Special Requirement (SR) 1 – Other Adopted Requirements ............................................ 4 2.10 SR 2 – Flood Hazard Delineation ....................................................................................... 4 2.11 SR 3 – Flood Protection Facilities ....................................................................................... 4 2.12 SR 4 – Source Control ........................................................................................................ 5 2.13 SR 5 – Oil Control ............................................................................................................... 5 2.14 SR 6 – Aquifer Protection Area ........................................................................................... 5 3.0 Offsite Analysis .............................................................................................................................. 5 3.1 Task 1 – Study Area Definition and Maps........................................................................... 5 3.2 Task 2 – Resource Review ................................................................................................. 6 3.3 Task 3 – Field Inspection .................................................................................................... 7 3.4 Task 4 – Drainage System Description and Problem Descriptions .................................... 8 4.0 Flow Control and Water Quality Facility Analysis and Design .................................................. 8 4.1 Existing Site Hydrology ....................................................................................................... 8 4.1.1 TDA 1 (Black River) ............................................................................................... 8 4.1.2 TDA 2 (Black River) ............................................................................................... 8 4.1.3 TDA 3 (Cedar River) .............................................................................................. 8 4.2 Developed Site Hydrology .................................................................................................. 8 4.2.1 TDA 1 (Black River) ............................................................................................... 8 4.2.2 TDA 2 (Black River) ............................................................................................... 9 4.2.3 TDA 3 (Cedar River) .............................................................................................. 9 4.3 Performance Standards ...................................................................................................... 9 Technical Information Report New Renton High School Project No. 2230388.10 4.4 Flow Control System ........................................................................................................... 9 4.5 Water Quality System ....................................................................................................... 10 4.6 Flow Control BMPs ........................................................................................................... 10 5.0 Conveyance System Analysis and Design ................................................................................ 10 6.0 Special Reports and Studies ...................................................................................................... 11 7.0 Other Permits ............................................................................................................................... 11 8.0 Construction Stormwater Pollution Prevention Plan (CSWPPP) Analysis and Design ....... 11 9.0 Bond Quantities, Facility Summaries, and Declaration of Covenant ..................................... 11 10.0 Operations and Maintenance Manual ........................................................................................ 12 11.0 Conclusion .................................................................................................................................... 12 Technical Information Report New Renton High School Project No. 2230388.10 Appendices Appendix A Exhibits A-1 ............Vicinity Map A-2 ............Existing Basins Map A-3 ............Floodplain Map A-4 ............Aquifer Protection Map A-5 ............Downstream Drainage Map A-6 ............Landslide Hazard Map A-7 ............Coal Mine Hazard Map A-8 ............Erosion Hazard Map A-9 ............Steep Slopes Map A-10 ..........Proposed Basin Map A-11 ..........Water Quality Areas A-12 ..........Water Quality Basins Appendix B Geotechnical Report Appendix C Flow Control Calculations Appendix D Water Quality Calculations Appendix E Conveyance Calculations (To be provided in a future submittal) Appendix F TESC Calculations (To be provided in a future submittal) Appendix G Bonds and Covenants (To be provided in a future submittal) Appendix H Operations and Maintenance Manual (To be provided in a future submittal) Technical Information Report New Renton High School Project No. 2230388.10 1.0 Project Overview The Renton School District (RSD) proposes to construct a new Renton High School at 400 South 2nd Street in Renton, Washington. The project consists of a new school building, parking lots, bus and parent drop-off and pick-up areas, outdoor landscape areas, and sports field, as well as utility and site improvements. Exact details of the phasing plan will be determined at a future date. Refer to Appendix A-1 for the project location. The project site encompasses 43 tax parcels, which are listed in Table 4 below, and is bounded by Airport Way to the north, Logan Avenue South to the east, North 2nd Street to the south, and Lake Avenue South and Shattuck Avenue South to the west. The existing Renton High School building and associated paved parking, drive lanes, and field are located on Parcel 0007200060. The school district will purchase 42 additional parcels and will vacate portions of South Tobin Street and South Tillicum Street to allow construction of the project. Existing improvements include the high school and its associated parking areas and play fields, as well as existing residences and commercial and light industrial properties. The original high school building from the 1930s and the Performing Arts Center from the 1990s will remain, while the portions constructed in the 1960s will be demolished. The project will be phased to allow the 1960s portion of the building to remain while the new building is constructed. The residential, commercial, and light industrial properties will be demolished in their entirety. Existing sidewalks and curb and gutter are located along the adjacent roadways within the public right-of-way. The adjacent sidewalks and curb and gutter are proposed for demolition and replacement on Logan Avenue South and Shattuck Avenue South. The entire pre-dedication site area (all tax parcels) is 35.2 acres. Right-of-way dedications are required along Airport Way, Logan Avenue North, Lake Avenue North, and South Tobin Street. Portions of South Tobin Street and South Tillicum Street will be vacated to construct the project. The entire site area (all tax parcels) including the dedications is 33.6 acres. The site has three separate discharge locations and is divided into three threshold discharge areas (TDAs), as mapped on Appendix A-2. Soils for this site are described in a Geotechnical Report attached as Appendix B. Table 1: TDA 1 Land Cover Areas Aimp (ac) Aperv (ac) Total (ac) Existing 0.96 0.31 1.27 Proposed 0.43 0.41 0.84 Table 2: TDA 2 Land Cover Areas Aimp (ac) Aperv (ac) Total (ac) Existing 17.82 10.57 28.39 Proposed 22.54 6.76 29.30 Table 3: TDA 3 Land Cover Areas Aimp (ac) Aperv (ac) Total (ac) Existing 4.77 2.08 6.85 Proposed 5.06 1.30 6.36 The proposed project will slightly change the basin boundaries. As a result, the TDA areas between existing and proposed conditions are not exactly the same. Technical Information Report New Renton High School Project No. 2230388.10 Table 4: List of Tax Parcels Parcel Property Address Lot size (SF) Current Use, Built Date Bldg. Size (SF) 1. 722930-0490 301-309 Airport Way 18,000 Warehouse, 1947 26,954 2. 722930-0545 455 Airport Way 34,000 Restaurant, 1949 12,342 3. 722930-0580 511 Airport Way 16,000 Vacant -- 4. 722930-0595 43 Logan Avenue S 4,700 Office, 1956 2,139 5. 722930-0635 51 Logan Avenue S 4,280 SF Home, 1916 6. 722930-0630 55 Logan Avenue S 5,429 SF Home, 1925 1,560 7. 000720-0043 59 Logan Avenue S 5,350 SF Home, 1902 950 8. 000720-0017 75 Logan Avenue S 5,500 SF Home, built 1901 900 9. 000720-0016 81 Logan Avenue S 11,000 SF Home, built 1922 920 10. 569600-0190 97 Logan Avenue S 5,855 SF home, built 1905 1,420 11. 569600-0185 103 Logan Avenue S 4,363 SF home, built 1938 1,470 12. 569600-0180 XX Logan Avenue S 4,787 Vacant 13. 569600-0170 109 Logan Avenue S 5,000 SF home, built 1900 1,270 14. 569600-0169 XX Logan Avenue S 5,000 Vacant -- 15. 569600-0165 117 Logan Avenue S 5,000 SF home, 1900 980 16. 569600-0160 121 Logan Avenue S 5,000 SF Home, 1900 1,910 17. 569600-0155 127 Logan Avenue S 5,000 Duplex, 1907 2,370 18. 569600-0150 129 Logan Avenue S 5,000 SF home, 1901 1,760 19. 569600-0145 526 2nd Avenue S 5,000 Parking lot 20. 569600-0140 526 2nd Avenue S 5,000 El Kiosko, 1949 754 21. 000720-0167 54-56 Shattuck Avenue S 6,600 Duplex, Built 1948 1,630 22. 000720-0171 58-60 Shattuck Avenue S 6,534 Duplex, 1948 1,630 23. 000720-0034 300-302 S Tobin Street 6,969 Duplex, 1948 2,030 24. 000720-0035 312 S Tobin Street 8,701 SF Home, Built 1923 2,000 25. 000720-0033 314 S Tobin Street 8,889 SF Home, 1925 1,740 26. 000720-0036 316 S Tobin Street 10,197 SF Home, 1922 2,270 27. 000720-0037 402 S Tobin Street 17,859 SF Home, 1949 3,360 28. 000720-0179 406 S Tobin Street 12,750 SF Home, 1925 1,240 29. 000720-0038 408 S Tobin Street 5,250 SF Home, 1953 880 30. 000720-0060 409 S Tobin Street District Warehouse, 1964 31. 000720-0039 414 S Tobin Street 18,000 Parking Lot 32. 000720-0078 416 S Tobin Street 4,912 SF Home, 1997 1,080 33. 000720-0079 418 S Tobin Street 4,916 SF Home, 1997 1,080 34. 000720-0072 420 S Tobin Street 7,720 SF Home, 1902 2,080 35. 000720-0110 500 S Tobin Street 4,747 SF Home, 1902 1210 36. 000720-0108 502 S Tobin Street 5,335 SF Home, 2004 1,480 37. 000720-0114 504 S Tobin Street 6,881 SF Home, 1902 2,250 38. 000720-0040 508 S Tobin Street 16,965 SF Home, 2015 1,410 39. 000720-0127 509 S Tobin Street 7,840 SF Home, 1926 1,540 40. 000720-0128 513 S Tobin Street 5,500 Duplex, 1977 2,390 41. 000720-0041 518 S Tobin Street 11,291 SF Home, 1900 1,520 42. 000720-0214 311 S Tillicum Street 7,810 SF Home, 2007 2,550 43. 000720-0060 400 2nd Avenue S 1,011,898 Renton High School 264,797 Technical Information Report New Renton High School Project No. 2230388.10 The engineered drainage system for the proposed site will not alter existing discharge locations from the site. Runoff from most of the site (TDA 1 and TDA 2) will discharge to Lake Avenue North, South 2nd Street, or South Tobin Street. Runoff from the easternmost part of the site (TDA 3) will discharge to Logan Avenue South. The 2021 King County Surface Water Design Manual (KCSWDM) and 2022 City of Renton Amendments to the King County Surface Water Design Manual (City of Renton Amendments) establish the methodology and design criteria used for the project. 2.0 Conditions and Requirements Summary The project triggers Full Drainage Review because it results in more than 7,000 square feet of land disturbing activity and over 2,000 square feet of new and/or replaced impervious surface . Below is a summary of how the proposed project will meet the Core Requirements (CR) and Special Requirements (SR). 2.1 CR 1 – Discharge at the Natural Location The site is located within the Lower Cedar River and the Black River Drainage Basins. The site is divided into three TDAs. Most of the site discharges to TDA 1 and TDA 2 to the Black River Wetlands, while a small portion discharges to TDA 3 to the Cedar River. T he Black River Wetlands lead to the Duwamish River and to Puget Sound in the SoDo District in Seattle. The Cedar River leads to Lake Washington, which discharges through the Lake Washington Ship Canal to Puget Sound in the Ballard District of Seattle. 2.2 CR 2 – Offsite Analysis AHBL staff performed a Level One Downstream Analysis for the project on August 4, 2025. The analysis included: • Defining and mapping the study area. • Reviewing available information on the study area. • Field inspecting the study area. • Analyzing the existing drainage system, including its existing and predicted problems, if any. Please refer to Section 3.0 for the full offsite analysis. 2.3 CR 3 – Flow Control The Western Washington Hydrology Model (WWHM) was used to model the existing stormwater conditions and design a detention pipe system for the project. TDA 1 and TDA 2 discharge to the Black River, which requires flow control. Because the project areas have been urbanized with more than 40% impervious area since 1985, this TDA is subject to the Flow Control Duration Standard Match Existing Conditions requirement, in accordance with Section 1.2.3.1.B of the KCSWDM. These TDAs area also subject to the wetland protection standard due to the wetland area around the Black River. TDA 3 discharges to the Cedar River, which is flow-control exempt. As a result, no flow control is required for this basin. Flow control will be provided through the use of buried detention pipes. WWHM is used to model the hydrologic conditions. Flow Control design is detailed in Section 4.4 of this report. Technical Information Report New Renton High School Project No. 2230388.10 2.4 CR 4 – Conveyance System The project will collect drainage from parking lots, playfields, and roofs, and direct it through a series of underground pipes and catch basins to the public stormwater system. Drainage will be directed to detention or water quality facilities, where required. Conveyance calculations will be provided in a future submittal and will be detailed in Section 5.0 of this report. 2.5 CR 5 – Erosion and Sediment Control Onsite land disturbance will consist of clearing the work site, demolition, and regrading. Erosion and sediment control will be provided with the use of temporary and permanent seeding within the work limits, silt fence or wattles, inlet sediment protection, stabilized construction entrance, sedimentation ponds, and temporary stormwater tanks. A Temporary Erosion and Sedimentation Control Plan will be included in the permit plan set. Refer to Section 8.0 for Construction Stormwater Pollution Prevention Plan (CSWPPP) analysis and design. 2.6 CR 6 – Maintenance and Operations Maintenance and operations of all drainage facilities will be by the owner. Operations and Maintenance will be detailed in Section 10.0 of this report. 2.7 CR 7 – Financial Guarantees and Liability This project will provide financial guarantees and liability per City of Renton requirements. This is detailed in Section 9.0 of this report. 2.8 CR 8 – Water Quality The new pollution generating impervious surfaces (PGIS) for the proposed site include the paved parking areas, maintenance, fire access loops, parking lot, and vehicle access. Onsite flows will be treated to meet the performance standard of the Metals Water Quality Menu by using Contech Filterra structures. The site is within Zone 1 and Zone 2 of the Aquifer Protection Zone. Therefore, bioretention and stormwater wetlands are prohibited. Water quality is discussed in detail in Section 4.5 of this report . 2.9 SR 1 – Other Adopted Requirements The project is included in the Black River and Lower Cedar River Drainage Basins. City and County basin requirements will be followed where applicable. 2.10 SR 2 – Flood Hazard Delineation The proposed project is not in or adjacent to the 100-year floodplain. Refer to Appendix A-3 for the Floodplain Map. 2.11 SR 3 – Flood Protection Facilities This project does not rely on existing flood protection facilities, nor will it modify or construct new flood protection facilities. Technical Information Report New Renton High School Project No. 2230388.10 2.12 SR 4 – Source Control The proposed project is an educational facility; it is classified as a commercial site for source control purposes. The dumpster area will have a roof and will drain to sanitary sewer to prevent stormwater from contamination. 2.13 SR 5 – Oil Control The site does not meet high-use criteria and is not subject to oil control measures. 2.14 SR 6 – Aquifer Protection Area This project is located within Aquifer Protection Zones 1 and 2 per the City of Renton Sensit ive Areas Aquifer Protection map. The east half of the site is in Zone 1 and the west half is in Zone 2. In Zone 1, stormwater facilities are not allowed to have direct contact with soil, while in Zone 2, such facilities are allowed with an impermeable liner. As a result, ponds, infiltration, and other facilities that require soil contact, are not permitted. Refer to Appendix A-4 for the Aquifer Protection map. 3.0 Offsite Analysis There are no upstream tributary areas contributing drainage to the basin area. 3.1 Task 1 – Study Area Definition and Maps The Renton School District (RSD) proposes to renovate and expand Renton High School at 400 South 2nd Street, Renton, Washington. AHBL staff visited the site on August 4, 2025. The project site lies within both the Black River and Lower Cedar River Drainage Basins, as delineated by the City of Renton COR Maps. The project site basin receives no upstream stormwater. The project discharges to three separate discharge locations that will be referred to as TDA 1, TDA 2, and TDA 3. Refer to Appendix A-5 for a map of the downstream system. TDA 1 Downstream Discharge 1 from TDA 1 is defined as the south-central and eastern portions of the site. It has an area of 1.28 acres. The basin discharges west to the flow line in South 2nd Street and to the south to a storm line in Shattuck Avenue South. Stormwater that flows south off the site is intercepted by one of five catch basins in the east flowline of South 2nd Street. All five of these catch basins are tightlined north to a 12- to 15-inch conveyance line running west on the north side of South 2nd Street that enters a Type II manhole at the intersection with Shattuck Avenue South. It is then directed south to a series of Type II manholes and an 18-inch stormwater main on the west side of Shattuck Avenue South. At the intersection with South 4th Place, the TDA is over the required one-quarter mile downstream of the project site. The discharge continues flowing south toward SW 7th Street for another quarter mile. At SW 7th Street, the discharge is rerouted west for about a mile . The stormwater then flows north on Naches Avenue South for about 650 feet, where the stormwater is discharged into the Black River. Technical Information Report New Renton High School Project No. 2230388.10 TDA 1 and TDA 2 converge at the 500 block of SW 7th Street. TDA 2 Downstream Discharge 2 from TDA 2 is defined as the west and center portions of the site. It has the largest area of all the basins, totaling 29.49 acres. TDA 2 stormwater discharges to the eastern flowline of Lake Avenue South, where it is intercepted by a series of Type I catch basins. Stormwater flows west 25 feet in an 8-inch pipe to a Type II catch basin at the north side of the intersection of South 2nd Street and Lake Avenue South. A 17-foot, 24-inch pipe conveys runoff across South 2nd Street to the south to another Type II catch basin, located in the adjacent sidewalk. A 30-inch pipe conveys stormwater south 77 feet to another Type II catch basin in the Safeway parking lot. The runoff travels through a 30-inch pipe, 373 feet southwest throughout a series of Type II manholes located within the Safeway parking lot. The runoff is then directed 315 feet west toward the neighboring property through a 36-inch pipe and Type II catch basins. The runoff then enters a 197-foot concrete pipe that travels below the intersection of SW Sunset Boulevard and Rainier Avenue South, connecting to a Type II catch basin located in the O’Reilly Auto Parts parking lot. The stormwater is then routed 364 feet through three Type II catch basins to a Type II catch basin located one-quarter mile from the project site. The stormwater is conveyed through a series of public and private stormwater mains and discharged into the Black River. TDA 1 and TDA 2 converge at the 500 block of SW 7th Street. TDA 3 Downstream TDA 3 stormwater discharges west to the flowline of Logan Avenue South and drains east, where it is intercepted by a catch basin at the southwest corner of the intersection of Airport Way and Logan Avenue South. Stormwater will flow north in a 112-foot, 24-inch pipe to a Type II catch basin in the island in the middle of the intersection. A 24-inch pipe conveys water 119 feet north toward East Perimeter Drive to a Type II catch basin. A 24-inch concrete pipe conveys the water 74 feet north, discharging to the Cedar River. This discharge point is less than one-quarter mile from the project site. Per the City of Renton COR Maps, the pipe outfall should be located 74 feet northwest of East Perimeter Road. AHBL could not locate the discharge point due to the discharge point being located on a steep ridge with heavy vegetation. 3.2 Task 2 – Resource Review The following resources were reviewed to discover any existing or potential problems in the study area: • Adopted Basin Plans: The project site lies within the Black River and Lower Cedar River Drainage Basins. Requirements for the Lower Cedar River Basin Plan will be followed where applicable. • Offsite Analysis Reports: AHBL staff has not located offsite analysis reports for projects near the Renton High School project site. Technical Information Report New Renton High School Project No. 2230388.10 • FEMA Map: FEMA Flood Insurance Rate Map 53033C0977G, dated August 19, 2020 (see Appendix A-3), indicates the project site lies within the 0.2% annual chance of flood hazard. • City of Renton Sensitive Areas Landslide Hazard Map (see Appendix A-6): The project site is not located within the sensitive areas Landslide Hazard Area. • City of Renton Aquifer Protection Zone Map (see Appendix A-4): The project site is within Aquifer Protection Zones 1 and 2. Requirements for Zones 1 and 2 of the Aquifer Protection Zone will be followed, where applicable. • City of Renton Coal Mine Hazard Map (see Appendix A-7): The project site is located outside the coal mine hazard area. • City of Renton Erosion Hazard Map (see Appendix A-8): The project site is not within an erosion hazard area. • City of Renton Steep Slopes Map (see Appendix A-9): The project site is not within the steep slope area. • Soils Information: Refer to Appendix B for the Geotechnical Report. 3.3 Task 3 – Field Inspection On August 4, 2025, AHBL staff performed a Downstream Analysis of the drainage system receiving stormwater runoff from the proposed Renton High School. 1. Investigate any problems reported or observed during the resource review : No problems were reported or observed during the resource review. 2. Locate all existing/potential constrictions or lack of capacity in the existing drainage system: No constrictions or lack of capacity in the existing drainage system was observed. 3. Identify all existing/potential downstream drainage problems as defined in Section 1.2.2.1 : No existing/potential downstream drainage problems were observed. 4. Identify existing/potential overtopping, scouring, bank sloughing, or sedimentation : The vast majority of catch basins located within the roadways (South 2nd Street, Shattuck Avenue South, Tobin Avenue South, etc.) had roughly 2 to 3 inches of sediment. 5. Identify significant destruction of aquatic habitat or organisms (e.g., severe siltation, back erosion, or incision in a stream): No significant destruction of aquatic habitat or organisms was observed. 6. Collect qualitative data on features such as land use, impervious surfaces, topography, and soil types for the site: Land use on the project is a school site. Impervious surfaces include parking areas, buildings, and sidewalks. The topography is flat on the site, and the soil type is Ur, Urban Land. 7. Collect information on pipe sizes, channel characteristics, drainage structures, and relevant critical areas (e.g., wetlands, stream, and steep slopes): Pipe sizes were determined by using survey information and City of Renton COR Maps. 8. Verify tributary basins delineated in Task 1: Based on the topography onsite, the basin delineation based on the survey was confirmed. 9. Contact neighboring property owners or residents in the area about past or existing drainage problems, and describe these in the report (optional): This requirement is not applicable for this project. Properties on the site basin are proposed for demolition. 10. Note the date and weather conditions at the time of the inspection: The site visit occurred on August 4, 2025. The weather was sunny and 73 degrees. Technical Information Report New Renton High School Project No. 2230388.10 3.4 Task 4 – Drainage System Description and Problem Descriptions The site is located within the Lower Cedar River and Black River Drainage Basins. The site is divided into three TDAs: TDA 1 is located in the south portion of the site, TDA 2 is located in the central and western portion of the site, and TDA 3 is located in the northern and eastern portion of the site. The south basin (TDA 1) and central basin (TDA 2) drain to the public piped conveyance system that eventually discharges to the Black River. The east basin (TDA 3) drains to the public conveyance system, discharging to the Cedar River. No signs of flooding, overtopping, or erosion were evident at the time of the inspection. 4.0 Flow Control and Water Quality Facility Analysis and Design 4.1 Existing Site Hydrology 4.1.1 TDA 1 (Black River) Area (Acre) Peak Flow (cfs) Till Grass Impervious Total 2-Year 10-Year 100-Year 0.31 0.96 1.27 0.38 0.57 0.82 4.1.2 TDA 2 (Black River) Area (Acre) Peak Flow (cfs) Till Grass Impervious Total 2-Year 10-Year 100-Year 10.57 17.82 28.39 7.48 11.30 16.64 4.1.3 TDA 3 (Cedar River) Area (Acre) Peak Flow (cfs) Till Grass Impervious Total 2-Year 10-Year 100-Year 2.08 4.77 6.85 1.95 2.91 4.23 Refer to Figure A-2, Existing Basin Map, for delineation of the existing drainage areas. 4.2 Developed Site Hydrology 4.2.1 TDA 1 (Black River) Area (Acre) Detained Peak Flow (cfs) Till Grass Impervious Total 2-Year 10-Year 100-Year Basin 1 1.58 2.72 4.30 0.19 0.30 0.45 The flows for this TDA are reduced compared to existing conditions because the total area of this basin will be reduced by the proposed development. Technical Information Report New Renton High School Project No. 2230388.10 4.2.2 TDA 2 (Black River) Area (Acre) Detained Peak Flow (cfs) Till Grass Impervious Total 2-Year 10-Year 100-Year Basin 2A 5.82 16.63 22.45 Basin 2B 0.94 5.91 6.85 Total 6.76 22.54 29.30 7.07 10.47 15.14 The flows for this TDA are reduced compared to existing conditions due to a detention system in the southwest portion of the site. 4.2.3 TDA 3 (Cedar River) Area (Acre) Detained Peak Flow (cfs) Till Grass Impervious Total 2-Year 10-Year 100-Year Basin 3 1.30 5.06 6.36 2.01 2.95 4.24 Flows for this basin are slightly increased. However, TDA 3 is flow-control exempt and matching flows is not required. Refer to Figure A-10, Proposed Basin Map, for delineation of the developed drainage areas and flow routes. 4.3 Performance Standards Per the KCSWDM, Flow Control Application Map, the site is subject to the Flow Control Duration Standard (Existing Conditions). The flow control duration standard requires runoff from urban developments to be detained and released at a rate that matches the flow duration of the existing condition rates from the 2-, 10-, and 100-year peak flow. Developed peak discharge rates shall match existing peak discharge rates for the 2-, 10-, and 100-year return periods. The proposed detention pipes will detain and release at a required rates, meeting the Flow Control standards. In accordance with the KCSWDM and City of Renton Amendments, onsite flows from the PGIS will be treated to meet the performance standards for the Metals Water Quality Menu. The proposed Contech Filterra structures will exceed the performance standards of the Metals Water Quality Menu. 4.4 Flow Control System The proposed stormwater flow control system is designed to meet the requirements of the KCSWDM and City of Renton Amendments. Flow control will be provided through the use detention within buried detention pipe. WWHM was used to size the detention tank and outlet structures. City of Renton Amendments Section 1.2.3.3 states that ”all proposed projects, including redevelopment projects, must provide onsite flow control facilities to mitigate the impacts of increased storm and surface water runoff generated by the addition of new impervious surface and any related land conversion.” Technical Information Report New Renton High School Project No. 2230388.10 Based on the site being in Aquifer Protection Zones 1 and 2, infiltration is not allowed onsite. In addition, the geotechnical report indicates the site soils are not conducive for infiltration . Therefore, a detention system is proposed for the project area. Flow control calculations were performed using WWHM. Calculations are provided as Appendix C. 4.5 Water Quality System The new PGIS for the proposed site includes all paved parking and maintenance access areas, as well as the artificial turf fields. As mentioned above, onsite flows will be treated to specifications provided by the Metals Water Quality standards of the City’s drainage code, using Contech Filterra structures. Because of the layout of the surrounding public streets, and area exchange is required to meet the water quality standard. Appendix A-11 shows the areas that require treatment, as well as showing how the area exchange proposed meets the stormwater requirements. Water quality basins are mapped in Appendix A-12. Per City of Renton Amendments Section 3.2, WWHM was used to size the Filterra structures (see Appendix D, Water Quality Calculations). 4.6 Flow Control BMPs KCSWDM Section 5.2 requires “projects that are subject to Core Requirement #3 and will not be served by infiltration facilities per Section 5.4 (p. 5-57) must apply flow control BMPs to either supplement the flow mitigation provided by required flow control facilities or pr ovide flow mitigation where flow control facilities are not required.” The project falls under the Large Lot High Impervious BMP Requirements of the KCSWDM. City of Renton Amendments Section 1.3.6, Special Requirement #6: Aquifer Protection Area, states that if a proposed project is in Zones 1 or 2 of the Aquifer Protection Area, then the following facilities are prohibited: open facilities, flow control BMPs, and open conveyance systems . The site is in a Zone 1 and Zone 2 APA (see Appendix A-4); therefore, the site is exempt from flow control BMPs per Special Requirement 6. 5.0 Conveyance System Analysis and Design Based on KCSWDM Section 1.2.4.1, new pipe systems shall be designed with sufficient capacity to convey and contain the 25-year peak flow, with a minimum of 6 inches of freeboard between the design water surface and structure grate. In addition, runoff from the 100-year peak storm event shall not create or aggravate a severe flooding problem or severe erosion problem. The new pipe system has sufficient capacity for a 25-year peak flow, and the system has been designed to provide more than 6 inches of freeboard between the design water surface and structure grate during the 25-year peak storm event. No severe flooding problems or severe erosion problems will be created or aggravated in the 100-year storm event. Parking lot drainage will be collected in catch basins and directed through a series of underground pipes to Filterra water quality systems. Roof drainage will be collected in a series of 6-inch pipes before being directed to existing storm drainage systems, both onsite and in the right-of-way. Drainage for play fields will be collected through an underdrain system to Filterra devices. The southwest portion of the site will be directed to a detention tank system, with the remainder going directly to the public drainage system without detention. Conveyance calculations will be provided in a future submittal and included in Appendix E . Technical Information Report New Renton High School Project No. 2230388.10 6.0 Special Reports and Studies A Geotechnical Report dated September 3, 2025, prepared by Associated Earth Sciences, Inc., can be found in Appendix B. 7.0 Other Permits This project will be constructed in phases, with each phase having its own building permit and site development permit. The exact phasing plan has not yet been determined at this time. In addition, a National Pollutant Discharge Elimination System (NPDES) General Permit will be required for this project. This project will also need permits from the Federal Aviation Administration (FAA) due to its proximity to Renton Airport. 8.0 Construction Stormwater Pollution Prevention Plan (CSWPPP) Analysis and Design The proposed development shall comply with guidelines set forth in City of Renton drainage requirements. The plan will include erosion/sedimentation control features designed to prevent sediment-laden runoff from leaving the site or adversely affecting critical water resources during construction. The following measures will be shown on the ESC plans and will be used to control sedimentation/ erosion processes: • Clearing Limits – All areas to remain undisturbed during the construction of the project will be delineated prior to any site clearing or grading. • Cover Measures – Cover measures will be implemented for the disturbed areas. • Perimeter Protection – Filter fabric fences for site runoff protection will be provided at the downstream site perimeter. • Traffic Area Stabilization – Traffic area stabilization is not applicable for this project. • Sediment Retention – Inlet sediment protection will be utilized as part of this project. • Storm Drain Inlet Protection – Inlet sediment protection will be provided on all new and existing catch basins downstream of construction activities. • Surface Water Collection – Catch basins and conveyance pipes will provide surface water collection. • Dewatering Control – Dewatering Control is not applicable for this project. • Dust Control – Dust control measures, including sweeping and water truck, will be implemented when exposed soils are dry to the point that wind transport is possible; and roadways, drainage ways, or surface waters are likely to be impacted. • Flow Control – Flow control is provided with sediment ponds and temporary stormwater tanks. TESC Calculations will be included in a future submittal in Appendix F . 9.0 Bond Quantities, Facility Summaries, and Declaration of Covenant Bond Quantities and a Declaration of Covenant will be included in a future submittal in Appendix G. Technical Information Report New Renton High School Project No. 2230388.10 10.0 Operations and Maintenance Manual Maintenance and operations of all onsite drainage facilities will be maintained by the Renton School District. The Operations and Maintenance Manual will be included in a future submittal in Appendix H. 11.0 Conclusion This site has been designed to meet or exceed the requirements of the 2024 King County Surface Water Design Manual, as amended by the 2022 City of Renton Amendments to the King County Surface Water Design Manual. Flow calculations and modeling use City of Renton standards for sizing stormwater conveyance. This analysis is based on data and records either supplied to or obtained by AHBL. These documents are referenced within the text of the analysis. The analysis has been prepared using procedures and practices within the standard accepted practices of the industry. AHBL, Inc. Brian Schend, PE Senior Engineer BJS/lsk September 2025 Q:\2023\2230388\WORDPROC\Reports\20250912 Rpt (TIR) 2230388.10.docx Technical Information Report New Renton High School Project No. 2230388.10 Appendix A Exhibits A-1 .................... Vicinity Map A-2 .................... Existing Basins Map A-3 .................... Floodplain Map A-4 .................... Aquifer Protection Map A-5 .................... Downstream Drainage Map A-6 .................... Landslide Hazard Map A-7 .................... Coal Mine Hazard Map A-8 .................... Erosion Hazard Map A-9 .................... Steep Slopes Map A-10 .................. Proposed Basin Map A-11 .................. Water Quality Areas A-12 .................. Water Quality Basins VICINITY MAP I405 AIRPORT WAY S TOBIN ST S 2ND ST R A I N I E R A V E A-1 Vicinity Map T T T T T T TT T TDA 3 PERVIOUS 2.08 AC IMPERVIOUS 4.77 AC TOTAL AREA 6.85 AC TDA 2 PERVIOUS 10.57 AC IMPERVIOUS 17.82 AC TOTAL AREA 28.39 AC TDA 1 PERVIOUS 0.31 AC IMPERVIOUS 0.96 AC TOTAL AREA 1.27 AC S TOBIN ST S TOBIN ST SH A T T U C K A V E S AIRPORT WAY LO G A N A V E S LO G A N A V E S L A K E A V E S S 2nd ST S TILLICUM ST 1930s BUILDING 1990s BUILDING (IPAC) 1960s BUILDING 1960s BUILDING 1960s BUILDING 1960s BUILDING 2215 North 30th Street, Suite 300, Tacoma, WA 98403 253.383.2422 TEL 253.383.2572 FAX JOB NO. DATE: RENTON HIGH SCHOOL EXISTING BASINS MAP A-2 2230388.10 9/11/2025 LEGEND TDA 1 - BLACK RIVER TDA 2 - BLACK RIVER TDA 3 - CEDAR RIVER N GRAPHIC SCALE 0 80 160 1" = 80 FEET 40 National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250 Feet Ü SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOOD HAZARD AREAS Without Base Flood Elevation (BFE) Zone A, V, A99 With BFE or DepthZone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areas of 1% annual chance flood with average depth less than one foot or with drainage areas of less than one square mileZone X Future Conditions 1% Annual Chance Flood HazardZone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to LeveeZone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood HazardZone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 1/12/2024 at 6:55 PM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location. 1:6,000 122°13'1"W 47°29'9"N 122°12'24"W 47°28'44"N Basemap Imagery Source: USGS National Map 2023 Appendix A-3 9,0281505 City of Renton Aquifer Protection Zone WGS_1984_Web_Mercator_Auxiliary_Sphere Notes None 1023 0 512 1023 Feet All data, information, and maps are provided "as is" without warranty or any representation of accuracy, timeliness of completeness. The burden for determining accuracy, completeness, timeliness, merchantability and fitness for or the appropriateness for use rests solely on the user. Legend Wellhead Protection Area Zones Zone 1 Zone 1 Modified Zone 2 Coalmines High Moderate Unclassified Erosion Hazard - High Landslide Very High High Moderate Unclassified Environment Designations Natural Shoreline High Intensity Shoreline Isolated High Intensity Shoreline Residential Urban Conservancy Jurisdictions Streams (Classified) S - Shoreline F - Fish Np - Non-Fish Ns - Non-Fish Seasonal Unclassfied Wetlands Streets 2023.sid Red: Band_1 Green: Band_2 Blue: Band_3 Appendix A-4 2215 North 30th Street, Suite 300, Tacoma, WA 98403 253.383.2422 TEL 253.383.2572 FAX JOB NO. DATE: RENOTN HIGH SCHOOL DOWNSTREAM ANALYSIS EX-X 2230388.10 AUG2025 R A I N I E R A V E S RA I N I E R A V E S SW S U N S E T B L V D S 3RD ST S 3RD ST S 3RD PL S 4TH P L S 2ND ST LO G A N A V E S LA K E A V E S AIRPORT WAY SH A T T U C K A V E S SH A T T U C K A V E S MO R R I S A V E S MO R R I S A V E S BU R N E T T A V E S BU R N E T T A V E S BU R N E T T A V E S S TOBIN ST S TOBIN ST PROJECT SITE DOWNSTREAM ANALYSIS NOT TO SCALE LEGEND TDA 1 TDA2 TDA3 633 LF 12" DIA POLYPROPYLENE 153 LF 12" DIA CONCRETE PIPE 514 LF 18" DIA POLYPROPYLENE PIPE 541 LF 24" DIA POLYPROPYLENE PIPE 343 LF 36" DIA POLYPROPYLENE PIPE S 4TH ST 1/4 MILE POINT 77 LF 24" DIA POLYETHYLENE PIPE 521 LF 30" DIA POLYPROPYLENE PIPE 170 LF 36" DIA POLYPROPYLENE PIPE 197 LF CONCRETE PIPE 364 LF 18" DIA DI PIPE 1/4 MILE POINT 510 LF 24" DIA CONCRETE PIPE OUTFALL TO CEDAR RIVER A-5 4,514752 City of Renton Landslide Hazard Map WGS_1984_Web_Mercator_Auxiliary_Sphere Notes None 512 0 256 512 Feet All data, information, and maps are provided "as is" without warranty or any representation of accuracy, timeliness of completeness. The burden for determining accuracy, completeness, timeliness, merchantability and fitness for or the appropriateness for use rests solely on the user. Legend Coalmines High Moderate Unclassified Erosion Hazard - High Landslide Very High High Moderate Unclassified Environment Designations Natural Shoreline High Intensity Shoreline Isolated High Intensity Shoreline Residential Urban Conservancy Jurisdictions Streams (Classified) S - Shoreline F - Fish Np - Non-Fish Ns - Non-Fish Seasonal Unclassfied Wetlands Streets 2023.sid Red: Band_1 Green: Band_2 Blue: Band_3 Appendix A-6 9,0281505 City of Renton Coal Mine Hazard Map WGS_1984_Web_Mercator_Auxiliary_Sphere Notes None 1023 0 512 1023 Feet All data, information, and maps are provided "as is" without warranty or any representation of accuracy, timeliness of completeness. The burden for determining accuracy, completeness, timeliness, merchantability and fitness for or the appropriateness for use rests solely on the user. Legend Coalmines High Moderate Unclassified Streets 2023.sid Red: Band_1 Green: Band_2 Blue: Band_3 Appendix A-7 9,0281505 City of Renton Erosion Hazard Map WGS_1984_Web_Mercator_Auxiliary_Sphere Notes None 1023 0 512 1023 Feet All data, information, and maps are provided "as is" without warranty or any representation of accuracy, timeliness of completeness. The burden for determining accuracy, completeness, timeliness, merchantability and fitness for or the appropriateness for use rests solely on the user. Legend Coalmines High Moderate Unclassified Erosion Hazard - High Environment Designations Natural Shoreline High Intensity Shoreline Isolated High Intensity Shoreline Residential Urban Conservancy Jurisdictions Streams (Classified) S - Shoreline F - Fish Np - Non-Fish Ns - Non-Fish Seasonal Unclassfied Wetlands Streets 2023.sid Red: Band_1 Green: Band_2 Blue: Band_3 Appendix A-8 4,514752 City of Renton Steep Slopes Map WGS_1984_Web_Mercator_Auxiliary_Sphere Notes None 512 0 256 512 Feet All data, information, and maps are provided "as is" without warranty or any representation of accuracy, timeliness of completeness. The burden for determining accuracy, completeness, timeliness, merchantability and fitness for or the appropriateness for use rests solely on the user. Legend Slope City of Renton >15% & <=25% >25% & <=40% (Sensitive) >40% & <=90% (Protected) >90% (Protected) Streets 2023.sid Red: Band_1 Green: Band_2 Blue: Band_3 Appendix A-9 10 0023 040054 0 2 03 01 100023040054020301 BASIN 1 TDA 1 PERVIOUS 0.41 AC IMPERVIOUS 0.43 AC TOTAL AREA 0.84 AC UNDETAINED BASIN 2A TDA 2 PERVIOUS 5.82 AC IMPERVIOUS 16.63 AC TOTAL AREA 22.45 AC UNDETAINED BASIN 2B TDA 2 PERVIOUS 0.94 AC IMPERVIOUS 5.91 AC TOTAL AREA 6.85 AC TO DETENTION TANK 2B BASIN 3 TDA 3 PERVIOUS 1.30 AC IMPERVIOUS 5.06 AC TOTAL AREA 6.36 AC UNDETAINED 2215 North 30th Street, Suite 300, Tacoma, WA 98403 253.383.2422 TEL 253.383.2572 FAX JOB NO. DATE: RENTON HIGH SCHOOL PROPOSED BASINS A-10 2230388.10 9/11/2025 LEGEND BASIN 1 - NO DETENTION N GRAPHIC SCALE 0 80 160 1" = 80 FEET 40 BASIN 2A - NO DETENTION BASIN 2B - TO TANK 2B BASIN 3 - NO DETENTION DS DS DS DS DS DS DS DS DS DS DSDS DS DS DS DS DS DS DS DS DS DSDSDSDS DS DS DS DS DS DS DS DS DS DS DS DS DS DS 10 0023 040054 0 2 03 01 100023040054020301 74 8 8 S F 1493 SF 185 SF 341 SF 38 2 9 S F 42 1 S F 52 4 S F 183 SF 462 SF 1294 SF 581 SF 152 SF 475 SF 62 0 3 S F 89 9 1 S F 2353 SF 72 9 7 S F 11 6 1 S F 202 SF 266 SF 429 SF 364 SF 330 SF 1103 SF 137 SF 463 SF 740 SF 2215 North 30th Street, Suite 300, Tacoma, WA 98403 253.383.2422 TEL 253.383.2572 FAX JOB NO. DATE: RENTON HIGH SCHOOL WATER QUALITY AREAS A-11 2230388.10 9/11/2025 LEGEND TARGET AREA TREATED N GRAPHIC SCALE 0 80 160 1" = 80 FEET 40 TARGET AREA NOT TREATED NON-TARGET AREA TREATED AREA EXCHANGE SUMMARY TARGET NOT TREATED 19,860 SF NON-TARGET TREATED 27,604 SF EXCESS TREATED 7,744 SF 624,015 SF 19,860 SF 27,604 SF 10 0023 040054 0 2 03 01 100023040054020301 TREATMENT BASIN 1 PERVIOUS 0.45 AC IMPERVIOUS 0.95 AC TOTAL AREA 1.40 AC 0.0852 CFS OFF-LINE RATE TO FILTERRA 1 DS DS DS DS DS DS DS DS DS DS DSDS DS DS DS DS DS DS DS DS DS DSDSDSDS DS DS DS DS DS DS DS DS DS DS DS DS DS DS TREATMENT BASIN 5 PERVIOUS 0.27 AC IMPERVIOUS 1.86 AC TOTAL AREA 2.13 AC 0.1691 CFS OFF-LINE RATE TO FILTERRA 5 TREATMENT BASIN 6 PERVIOUS 0.11 AC IMPERVIOUS 0.98 AC TOTAL AREA 1.09 AC 0.0893 CFS OFF-LINE RATE TO FILTERRA 6 TREATMENT BASIN 7 PERVIOUS 0.04 AC IMPERVIOUS 3.73 AC TOTAL AREA 3.77 AC 0.3421 CFS OFF-LINE RATE TO FILTERRA 7 TREATMENT BASIN 8 PERVIOUS 1.57 AC IMPERVIOUS 6.93 AC TOTAL AREA 8.50 AC 0.6278 CFS OFF-LINE RATE TO FILTERRA 8 TREATMENT BASIN 9 PERVIOUS 0 AC IMPERVIOUS 2.72 AC TOTAL AREA 2.72 AC 0.2497 CFS OFF-LINE RATE TO FILTERRA 9 TREATMENT BASIN 10 PERVIOUS 0.10 AC IMPERVIOUS 0.11 AC TOTAL AREA 0.21 AC 0.0098 CFS OFF-LINE RATE TO FILTERRA 10 TREATMENT BASIN 11 PERVIOUS 0.24 AC IMPERVIOUS 0.58 AC TOTAL AREA 0.82 AC 0.0521 CFS OFF-LINE RATE TO FILTERRA 11 TREATMENT BASIN 12 PERVIOUS 0.27 AC IMPERVIOUS 0.51 AC TOTAL AREA 0.78 AC 0.0457 CFS OFF-LINE RATE TO FILTERRA 12 TREATMENT BASIN 13 PERVIOUS 0.06 AC IMPERVIOUS 0.40 AC TOTAL AREA 0.46 AC 0.0363 CFS OFF-LINE RATE TO FILTERRA 13 TREATMENT BASIN 2 PERVIOUS 0 AC IMPERVIOUS 1.91 AC TOTAL AREA 1.91 AC 0.1753 CFS OFF-LINE RATE TO FILTERRA 8 2215 North 30th Street, Suite 300, Tacoma, WA 98403 253.383.2422 TEL 253.383.2572 FAX JOB NO. DATE: RENTON HIGH SCHOOL WATER QUALITY BASINS A-12 2230388.10 9/11/2025 N GRAPHIC SCALE 0 80 160 1" = 80 FEET 40 FILTERRAS NUMBER FLOWRATE MIN TREATMENT AREA AREA PROVIDED (FT3/SEC)(IN3/HR)(IN2)(FT2) 1 0.0852 530,012 1636 11.36 4x4 = 16 SF 2 0.1753 1,090,506 3366 23.37 6x4 = 24 SF 5 0.1691 1,051,937 3247 22.55 6x4 = 24 SF 6 0.0893 555,517 1715 11.91 4x4 = 16 SF 7 0.3421 2,128,136 6568 45.61 6x8 = 48 SF 8 0.6278 3,905,418 12054 83.71 8x10.5 = 84 SF 9 0.2497 1,553,334 4794 33.29 6x6 = 36 SF 10 0.0098 60,964 188 1.31 4x4 = 16 SF 11 0.0521 324,104 1000 6.95 4x4 = 16 SF 12 0.0457 284,291 877 6.09 4x4 = 16 SF 13 0.0363 225,815 697 4.84 4x4 = 16 SF ALL FILTERRA UNITS SIZED FOR METALS TREATMENT AT 324 IN/HOUR PER WSDOE GULD APPROVAL Technical Information Report New Renton High School Project No. 2230388.10 Appendix B Geotechnical Report associated earth sciences incorporated Associated Earth Sciences, Inc. www.aesgeo.com Kirkland | Mount Vernon | Tacoma Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report RENTON HIGH SCHOOL REPLACEMENT Renton, Washington Prepared For: RENTON SCHOOL DISTRICT NO. 403 Project No. 20210249E002 September 3, 2025 Kirkland | Tacoma | Mount Vernon 425-827-7701 | www.aesgeo.com September 3, 2025 Project No. 20210249E002 Renton School District No. 403 7812 South 124th Street Seattle, Washington 98178 Attention: Brianne Tomlin Subject: Subsurface Exploration, Geologic Hazard, and Geotechnical Engineering Report Renton High School Replacement 400 South 2nd Street Renton, Washington Dear Brianne Tomlin: We are pleased to present our geotechnical engineering report for the proposed Renton High School campus replacement project. This report serves as an update to our preliminary draft report, dated May 15, 2024, to reflect current design plans. This report summarizes the results of our subsurface explorations, geologic hazard, and geotechnical engineering studies and offers design recommendations based on our present understanding of the project. Once project plans are finalized, we should review the plans and confirm or update our recommendations, where necessary. It should be noted that the subsurface explorations and analyses completed for this study were focused on the main school campus. Additional subsurface explorations and engineering studies will be completed for newly acquired properties located north of the campus prior to construction. We have enjoyed working with you on this study and are confident that the recommendations presented in this report will aid in the successful completion of your project. If you should have any questions or if we can be of additional help to you, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington ______________________________ G. Bradford Drew, P.E. Associate Engineer BD/ld – 20210249E002-007 SUBSURFACE EXPLORATION, GEOLOGIC HAZARD, AND GEOTECHNICAL ENGINEERING REPORT RENTON HIGH SCHOOL REPLACEMENT Renton, Washington Prepared for: Renton School District No. 403 7812 South 124th Street Seattle, Washington 98178 Prepared by: Associated Earth Sciences, Inc. 911 5th Avenue Kirkland, Washington 98033 425-827-7701 September 3, 2025 Project No. 20210249E002 Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Project and Site Conditions September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 1 I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report presents the results of Associated Earth Sciences, Inc.’s (AESI’s) subsurface exploration, geologic hazard, and geotechnical engineering study for the proposed replacement of the Renton High School campus in Renton, Washington. The site location is shown on the “Vicinity Map,” Figure 1. The approximate locations of explorations completed for this study are shown on the “Existing Site and Exploration Plan,” Figure 2, and the “Proposed Site and Exploration Plan,” Figure 3. Copies of the exploration boring logs and cone penetrometer test (CPT) results for this current study are included in Appendices A and B, respectively; copies of the logs for nearby historical explorations completed by AESI for previous studies are included in Appendix C; a groundwater hydrograph is presented in Appendix D; laboratory test results are included in Appendix E; our liquefaction analysis results are included in Appendix F; the results of a shear wave velocity survey completed at the school campus by the Washington Geological Survey (WGS) is attached in Appendix G; and the wellhead protection zone mapping of the project site and vicinity is included in Appendix H. 1.1 Purpose and Scope The purpose of this study was to provide subsurface soil and groundwater data to be utilized in the design of the project. Our study included reviewing available geologic literature, review of previous explorations completed at the site, advancing six exploration borings with three borings completed as groundwater level observation wells, advancing three CPTs, and performing a geologic study to assess the type, thickness, distribution, and physical properties of the subsurface sediments and shallow groundwater conditions across the project area. Geotechnical engineering studies were completed to determine the type of suitable foundations, allowable foundation soil bearing pressures, anticipated foundation settlements, drainage considerations, and stormwater infiltration feasibility. This report summarizes our current fieldwork and offers preliminary development recommendations based on our present understanding of the project. It should be noted that the subsurface explorations and analyses completed for this study were focused on the main school campus. Additional subsurface explorations and engineering studies will be completed for newly acquired properties located north of the campus prior to construction. A general assessment of the anticipated soils conditions and infiltration feasibility within the newly acquired properties to the north of the main school campus is discussed in Section 17.2 of this report. Our assessment is primarily based on recent site observations during the demolition of below-grade residential structures. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Project and Site Conditions September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 2 1.2 Authorization Written authorization to proceed with this study was granted by Renton School District No. 403 by means of signed Purchase Order, dated February 29, 2024. Our work was completed in general accordance with our scope of work and cost proposal dated October 31, 2023. This report has been prepared for the exclusive use of Renton School District No. 403 and their agents for specific application to this project. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our report was prepared. No other warranty, express or implied, is made. 2.0 SITE AND PROJECT DESCRIPTION The project site is located at the existing Renton High School campus in Renton, Washington, and consists of a single 23-acre parcel (King County Parcel No. 0007200060). The existing school buildings are currently located near the center of the parcel and include several classroom buildings, a gymnasium, and a maintenance building to the northeast. A parking lot occupies the southeast corner of the parcel and a softball field occupies the northeast corner. Tennis courts and three baseball fields currently occupy the western half of the parcel and are divided from the school building by a two-lane access road that connects South 2nd Avenue to South Tobin Street. The parcels surrounding the campus to the east and north of the campus generally consist of residential single-family lots. The existing school buildings are mostly two-story structures, the exception being the maintenance building to the northeast. The original Renton High School building was constructed in 1911 and replaced in 1932. Portions of the building were demolished and reconstructed in 1941. The school was then remodeled in 1969 and renovated in 1999. The 1999 renovation included the addition of the Performing Arts Center near the southeast corner of the site. The overall site topography is generally flat to very gently sloping to the northwest. Overall vertical relief across the school campus trending south to north is approximately 4 feet over a distance of about 850 feet. The Black River formerly passed through the project area along the western margin of the school campus, and the river channel onsite was filled after construction of the Ballard Locks in 1917. We understand that the existing buildings onsite are supported on deep foundations including augercast piles, driven pre-cast concrete piles, and timber piles. The project involves the significant replacement/renovation of the school campus and expansion to the north. Based on a design development plan set provided by BRIC Architecture, Inc., dated June 6, 2025, the campus replacement will include the following: Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Project and Site Conditions September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 3 New school buildings surrounding the existing Performing Arts Center within the southeast corner of the campus and extending to the north toward South Tobin Street. New parking lots to the north and west of the 1930’s historical building. A new track and field area within the footprint of the existing baseball fields to the west. The addition (campus expansion) of new athletic fields to the north within the existing 7-acre residential block that is bounded by South Tobin Street to the south, Shattuck Avenue South to the west, Airport Way to the north, and Logan Avenue South to the east. The proposed site improvements are shown on Figure 3. We understand that all of the new athletic fields will be surfaced with synthetic turf and an underdrain system. No infiltration facilities are planned at this time. 3.0 SITE EXPLORATION Our field study for this phase of the project was completed in April 2024 and included advancing six exploration borings (EB-1 through EB-6W) across the eastern half of the school campus, with three borings completed as groundwater level observation wells (EB-1W, EB-3W, and EB-6W), to define the shallow groundwater conditions below the site. We also advanced three CPT probes (CPT-01 through CPT-03) to supplement the boring information and for use in our liquefaction analysis. The exploration locations are shown on the “Existing Site and Exploration Plan,” Figure 2, and the “Proposed Site and Exploration Plan,” Figure 3. The various types of sediments, as well as the depths where characteristics of the sediments changed, are indicated on the exploration logs presented in Appendix A. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types in the field. The locations of our field explorations were determined by approximate measurements from known site features. The conclusions and recommendations presented in this report are based, in part, on the exploration borings completed for this study. The number, locations, and depths of the explorations were completed within site and budgetary constraints. Because of the nature of exploratory work below ground, extrapolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions might sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of variations between the field explorations may not become fully evident until construction. If variations are observed at that time, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Project and Site Conditions September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 4 3.1 Exploration Borings The exploration borings were completed by Advance Drill Technologies, Inc., an independent driller working under subcontract to AESI, by advancing a 6-inch outside-diameter, hollow-stem auger with a track-mounted drill rig. During the drilling process, samples were generally obtained at 2½- to 5-foot-depth intervals. As the borehole advanced below the water table, the driller added drilling fluid and water within the hollow-stem auger to help maintain borehole stability. After drilling, each borehole was backfilled with bentonite grout in combination with bentonite chips, and the surface was patched using turf in existing landscape areas and cold-mix asphalt patch in existing pavement areas. Disturbed, but representative samples were obtained by using the Standard Penetration Test (SPT) procedure in accordance with ASTM International (ASTM) D-1586. This test and sampling method consists of driving a standard 2-inch, outside-diameter, split-barrel sampler a distance of 18 inches into the soil with a 140-pound hammer free-falling a distance of 30 inches. The number of blows for each 6-inch interval is recorded, and the number of blows required to drive the sampler the final 12 inches is known as the Standard Penetration Resistance (“N”) or blow count. If a total of 50 is recorded within one 6-inch interval, the blow count is recorded as the number of blows for the corresponding number of inches of penetration. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils; these values are plotted on the attached exploration boring logs. The borings were continuously observed and logged by a geologist from our firm. The samples obtained from the split-barrel sampler were classified in the field and representative portions placed in watertight containers. The samples were then transported to our laboratory for further visual classification and laboratory testing. The exploration logs presented in Appendix A are based on the N-values, field observations, and drilling action. 3.2 Exploration Borings Completed as Observation Wells Three of the exploration borings (EB-1W, EB-3W, and EB-6W) were completed as 2-inch-diameter groundwater level observation wells. These wells were installed to allow for monitoring of seasonal groundwater levels. The wells were constructed with 10 feet of machine-slotted Schedule 40 polyvinyl chloride (PVC) well screen, solid, non-slotted, Schedule 40 PVC casing, and a flush monument. The well screen interval and approximately 3 feet of the annular space above each well screen was backfilled with filter sand. The wells were completed with a bentonite surface seal, a flush-mount well cover set in concrete, and a locking well cap. Well construction details are presented on the geologic and well construction logs for EB-1W, EB-3W, and EB-6W in Appendix A. Groundwater levels ranged from approximately 11.8 to 14.3 feet below the existing ground surface at the time of installation. Well EB-6W was developed on April 26, 2024, and EB-1W and EB-3W were developed on April 29, 2024. After well development, the static water level was measured at about 9.5 feet below existing grade within EB-1W, 12.1 feet within Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Project and Site Conditions September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 5 EB-3W, and 14.1 feet within EB-6W. Site hydrology is discussed in further detail in Section 4.4 of this report. 3.3 Cone Penetrometer Tests CPT probes CPT-01, CPT-02, and CPT-03 were performed by In Situ Engineering, working under subcontract to AESI, by pushing a 1.5-inch-diameter instrumented cone into the soil. The cone is instrumented with pressure transducers at the tip of the cone and along the sleeve of the cone to measure pressure and frictional resistance as the cone is pushed into the soil. Cone tip and sleeve resistance readings, as well as a pore water pressure transducer, provide a continuous record of the soil properties. This information can then be used to characterize soil type, density, and pore water pressure estimates, and support detailed soil liquefaction analysis and soil properties for ground improvement design. In addition, shear wave velocities were measured at approximate 3- to 6-foot-depth intervals at CPT-02. CPT-01, CPT-02, and CPT-03 were advanced to depths of 34 feet, 25 feet, and 20.5 feet below the existing ground surface, respectively, before encountering “refusal” likely due to an elevated gravel content or larger gravel-sized particles. The CPT logs are presented in Appendix B. 4.0 SUBSURFACE CONDITIONS Subsurface conditions at the project site were inferred from the field explorations accomplished for this study, visual reconnaissance of the site, and review of applicable geologic literature. The following sections describe observed site stratigraphy, regional geology, and local groundwater. The near-surface sediments encountered in our explorations generally consisted of existing fill overlying Holocene alluvial (river-deposited) sediments. The following section presents more detailed subsurface information organized from the shallowest (youngest) to the deepest (oldest) sediment types. 4.1 Stratigraphy The following subsections summarize our observations and interpretations of different sedimentary units observed in subsurface explorations in order of deposition from most recent to oldest. Asphalt Explorations EB-1W and EB-5 were located in the existing asphalt parking lots. Both explorations encountered about 3 inches of asphalt at the pavement surface. We did not observe any crushed rock base course material directly underlying the asphalt within EB-1W. We observed approximately 4 to 6 inches of crushed rock base course directly below the asphalt within EB-5. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Project and Site Conditions September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 6 Fill Existing fill soils (those not naturally deposited) were encountered directly below the ground surface within each of the exploration borings completed for this study. The fill generally consisted of slightly moist to moist, very loose to medium dense, brown to dark brown, silty fine to medium sand with variable gravel content and scattered to abundant organics (roots, rootlets, wood debris, and fine organics). Observed fill depths within EB-1W through EB-5 ranged from approximately 3.5 to 4.5 feet below the existing ground surface. The deepest fill was observed in EB-6W and extended to about 7 feet below the existing ground surface. The existing fill is not considered suitable for foundation support and warrants assessment and possible remedial preparation at the time of construction where pavements and flat work are planned. Excavated existing fill material is suitable for reuse in structural fill applications if such reuse is specifically allowed by project plans and specifications, if excessively organic and any other deleterious materials are removed, and if moisture content is adjusted to allow compaction to the specified level and to a firm and unyielding condition. Existing fill is not considered suitable as an infiltration receptor for stormwater. Holocene Alluvium - Black River Alluvium Directly below the existing fill within EB-1W through EB-5, we encountered a generally fine-grained deposit of interbedded fine sand and silt, interpreted to be representative of alluvial sediments associated with the Black River, which historically crossed the site. This deposit contained loose to medium dense, sand with variable silt content ranging from some silt to silty and trace to some gravel, ranging to soft silt and sandy silt. These alluvial sediments were deposited from low-energy flowing water and are relatively loose/soft. No Black River alluvium was encountered in EB-6. Holocene Alluvium - Cedar River Alluvium Sediments encountered below the Black River alluvium within EB-1W through EB-5, and beneath the existing fill in EB-6W, generally consisted of medium dense, gray to brownish gray, sand, gravelly sand ranging to sandy gravel. We interpret these sediments as alluvial and deltaic sediments associated with the Cedar River. These sediments occasionally displayed stratification and contained rare organics (wood debris). We infer that the N-values indicating a dense condition were overstated due to an elevated gravel content. For geotechnical considerations, the Cedar River alluvium is in a medium dense condition. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Project and Site Conditions September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 7 4.2 Previous Explorations and Studies Previous explorations and geotechnical studies were completed at the school campus by AESI in 1999, 2009, 2024, and April 2025, which included several borings and test pits in the vicinity of the proposed site improvements. The approximate locations of the previous explorations are shown on Figures 2 and 3, and copies of the exploration logs are included in Appendix C. On Figures 2 and 3, we have modified the exploration numbering system for these previous studies to include the year they were completed (e.g., EB-1-99) to avoid confusion with our current exploration numbering system. The previous studies included the following explorations: 4 borings (EB-1 through EB-4, completed March 1999) located around the perimeter of the Performing Arts Center on the south-central portion of the existing campus. These borings were advanced to depths ranging from 31.5 to 41.5 feet below existing site grades and encountered a surficial layer of fill underlain by alluvial sediments to the boring termination depth. Groundwater levels at the time of drilling ranged from about 4.5 to 12 feet below existing site grades. 4 test pits (EP-1 through EP-4, completed March 1999) located along the southern and western margins of the main school building to evaluate the type and condition of existing pile foundations. The pits were advanced to depths ranging from 5.5 to 11 feet below existing site grades and encountered a surficial layer of fill underlain by alluvial sediments. Groundwater seepage was encountered at about 11 feet at the time of excavation. Explorations EP-1 and EP-4 each exposed one treated timber pile beneath a perimeter foundation element, and explorations EP-2 and EP-3 each exposed one precast concrete pile. Our observations of the piles at the time of exposure are summarized below. Timber Pile Observations: At explorations EP-1 and EP-4, the general configuration of the foundation system included a foundation wall, with a relatively wider grade beam at the base, supported by timber piles connected to the bottom of the grade beams. Measurement of the pile diameters with a hand-held tape measure indicated pile butt diameters immediately beneath the grade beam connection of approximately 12 to 13 inches. We also used an increment borer to core a 0.2-inch-diameter sample of each timber pile. The cores indicated that the distance from edge to center of the piles was 6 to 6¼ inches, and that the depth of penetration of creosote treatment varied from about 0.3 to 0.7 inch. In general, the wood cores recovered from the piles appeared firm, sound, and free from visible weakness. Based on conventional estimates of Douglas Fir timber piles, namely tapering by 1 inch in diameter per 10 feet of length, and assuming a tip diameter of 9 inches, we estimated the pile lengths were on the order of 25 to 30 feet below the grade beams. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Project and Site Conditions September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 8 Precast Concrete Pile Observations: At explorations EP-2 and EP-3, we observed the concrete piles had an octagonal cross-section. The piles were located beneath a grade beam in the case of EP-2, and beneath a pile cap in the case of EP-3. The piles generally appeared symmetrical; however, it was typically only possible to measure the diameter in the orientation parallel to the edge of the grade beam or pile cap. Each of the exposed piles measured approximately 13 inches from face to face of the octagonal cross-section in the direction parallel to the grade beam or pile cap. There was no means to determine the length of the concrete piles at the time of exploration. Two additional test pits (EP-1 and EP-2, completed in July 2024) were excavated along the western side of the 1930’s historical building to aid us in making additional observations of the existing precast concrete piles. EP-1 and EP-2 were located near the southwest corner and midpoint of the building’s western exterior, respectively. One pile and connecting grade beam were exposed at each location. Each pile exposed consisted of a precast concrete pile with an irregular octagonal cross-section approximately 13 inches wide. Each pile was observed to be in good condition with no obvious signs of deterioration, cracking, or spalling. Additional information related to our pile observations is contained in a letter-report, titled “Existing Pile Observations and Estimated Capacities, Renton High School Replacement, Renton Washington,” dated August 22, 2024. 14 borings (EB-1 through EB-14, completed December 2009) located across the existing athletic fields within the western half of the campus. Borings EB-1 through EB-6 were advanced to a depth of about 36.5 feet below site grade, and borings EB-7 through EB-14 were advanced to about 6.5 feet below existing site grades. These borings generally encountered a surficial layer of fill underlain by alluvial sediments to the boring termination depth. The alluvial sediments generally graded from loose to dense with depth, although we infer that the N-values indicating a dense condition were overstated due to an elevated gravel content. Groundwater levels at the time of drilling ranged from about 7 to 10 feet below existing site grades. AESI observed and documented three separate attempts to advance vertical boreholes and install geothermal test loops (GTLs) in areas within/near the school campus that were under consideration for the installation of production loop fields. The test loop boreholes were labeled GTL-1 through GTL-3 and their approximate locations are shown on Figures 2 and 3. Overall, the alluvial sediments below the site were observed to contain zones of gravel and possible cobbles and/or boulders that could significantly delay progress during production drilling and/or result in shallow termination/abandonment of boreholes. There appears to be a considerable risk in pursuing a production loop field at the school campus due the highly variable and complex geologic setting. We understand that a production loop field is no longer under consideration at this time. Additional information regarding the geothermal drilling observations and test loop attempts are Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Project and Site Conditions September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 9 provided in a letter-report, titled “Thermal Conductivity Borings and Test Loop Installation, Renton High School Replacement, Renton, Washington,” dated April 25, 2025. In addition to previous work completed by AESI, the WGS completed a subsurface shear wave transmission velocity survey at the site in October 2020. The results of the survey are discussed further in the “Ground Motion/Seismic Site Class” section of this report and attached in Appendix G. The historical boring information and shear wave velocity survey were used to supplement the subsurface information obtained for this current study and to formulate preliminary recommendations for the design and development of the project. 4.3 Regional Geologic and Soils Mapping Review of the geologic map of the project area (Geologic Map of the Renton Quadrangle, King County, Washington, U.S. Geological Survey, Geologic Quadrangle Map GQ-405, by D.B. Mullineaux, [1965]) indicates that the site is expected to be underlain by modified land. Our interpretation of the sediments encountered in our recent explorations is in general agreement with the regional geologic map in that we encountered a layer of fill overlying native Holocene alluvial sediments, which is consistent with the history of the project area. The Black River previously crossed the western margin of the school campus and after construction of the Ship Canal and Ballard Locks, the Black River channel onsite was filled. Review of the regional soils mapping (Soil Survey of King County Area, Washington, U.S. Department of Agriculture [USDA], Soils Conservation Service [SCS] now referred to as Natural Resources Conservation Service [NRCS]) on the NRCS Web Soil Survey indicates that the subject site is underlain by Urban Land (Ur). Urban Land is soil that has been modified by disturbance of the natural layers with additions of fill material several feet thick. Our observations of the near-surface sediments encountered in our explorations are in general agreement with the soils mapping. 4.4 Hydrology Groundwater was encountered within the alluvial sediments in all six of the explorations completed for this study. The approximate depths to groundwater at the time of drilling along with post-development static water levels within the borings completed as wells (EB-1W, EB-3W, and EB-6W) are depicted on the subsurface exploration logs in Appendix A and summarized in Table 1 below. AESI has monitored seasonal groundwater levels within the on-site wells (EB-1W, EB-3W, and EB-6W) starting from well development in April 2024 through June 25, 2025. A hydrograph illustrating approximate groundwater elevations and precipitation amounts over time is presented in Appendix D. During this monitoring period, groundwater elevations have ranged from about 20 to 22 feet in August/September 2024 (seasonal low) to about 23.5 to 26 feet in Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Project and Site Conditions September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 10 late March/early April 2025 (seasonal high), corresponding to seasonal fluctuations of 3 to 4 feet. The shallowest depth to water was measured in EB-1W; water levels were on the order of 6 feet below ground surface at this location in late March 2025. At the time of this report, the well locations and elevations have not been established by an optical survey. Once surveyed, the groundwater elevation at each well location can be established. The groundwater observed at these boring locations is interpreted to be representative of the localized unconfined aquifer underlying the site within the alluvial deposits. Perched groundwater may also be present within the fill at the contact with the finer-grained Black River alluvium, particularly after large storm events or near existing utility backfill. At the locations of EB-2, EB-4, and EB-5, groundwater was encountered and measured at the time of drilling within the Black River alluvial sediments at depths of 13.3, 14.1, and 10 feet below existing grade, respectively. The wells within EB-1W and EB-3W were developed on April 29, 2024, and the static water level was measured at about 9.5 feet and 12.1 feet below existing grade, respectively. The well within EB-6W was developed on April 26, 2024, and the static water level was measured at about 14.1 feet below existing grade. It should be noted that groundwater conditions can vary considerably across short distances, and fluctuations in groundwater conditions may occur due to the time of the year, on- and off-site land use, and variations in the amount of rainfall. Table 1 Summary of Observed Groundwater Levels at Time of Drilling and Seasonal High Groundwater Exploration Boring No. Depth to Groundwater(1) (feet) Water-Bearing Unit Interpretation EB-1W 11.8 ATD(2) 5.9 Seasonal High(3) Black River Alluvium Localized Unconfined Aquifer EB-2 13.3 ATD Black River Alluvium Localized Unconfined Aquifer EB-3W 13.6 ATD 10.7 Seasonal High Black River Alluvium Localized Unconfined Aquifer EB-4 14.1 ATD Black River Alluvium Localized Unconfined Aquifer EB-5 10 ATD Black River Alluvium Localized Unconfined Aquifer EB-6W 14.3 ATD 12.6 Seasonal High Cedar River Alluvium Localized Unconfined Aquifer (1) Groundwater depths correspond to depth below the existing ground surface. (2) ATD = At Time of Drilling (April 9-11, 2024). (3) Seasonal high groundwater level corresponds to measurements made in late March/early April 2025. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Project and Site Conditions September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 11 Historical Groundwater Levels Historical explorations at the site have indicated groundwater levels as shallow as 4.5 feet at the time of drilling in early March. The approximate depths to groundwater at the time of drilling during previous studies at the site are summarized in Table 2 below. Table 2 Summary of Historical Groundwater Levels at Time of Drilling Exploration Boring No. Depth to Groundwater(1) (feet) At Time of Drilling Date Water-Bearing Unit Interpretation EB-1-09 7 12/22/2009 Black River Alluvium Localized Unconfined Aquifer EB-2-09 10 12/22/2009 Cedar River Alluvium Localized Unconfined Aquifer EB-3-09 8 12/22/2009 Black River Alluvium Localized Unconfined Aquifer EB-4-09 8 12/22/2009 Black River Alluvium Localized Unconfined Aquifer EB-5-09 9.5 12/22/2009 Black River Alluvium Localized Unconfined Aquifer EB-6-09 10 12/23/2009 Black River Alluvium Localized Unconfined Aquifer EB-1-99 ~4.5 3/11/1999 Recent Alluvium Localized Unconfined Aquifer EB-2-99 4.5 3/11/1999 Recent Alluvium Localized Unconfined Aquifer EB-3-99 12 3/11/1999 Recent Alluvium Localized Unconfined Aquifer EB-4-99 12.5 3/11/1999 Recent Alluvium Localized Unconfined Aquifer (1) Groundwater depths correspond to depth below the existing ground surface. 4.5 Laboratory Testing Grain-Size Analysis AESI performed eight grain-size analyses (sieves) on selected soil samples of the existing fill and native alluvial sediments to support soil classification in the field and to aid us in evaluating the suitability of the materials for potential reuse as structural fill, and to aid our liquefaction analysis. The laboratory test results are summarized in Table 3 below (and attached in Appendix E) with soil descriptions based on the ASTM D-2487 Unified Soil Classification System (USCS). Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Project and Site Conditions September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 12 Table 3 Summary of Laboratory Test Results Exploration Boring No. Sample Depth (feet) Geologic Unit USCS Soil Description Fines Content (%) EB-1W 5 Black River Alluvium Sandy SILT, trace gravel (ML) 71.2 EB-1W 35 Cedar River Alluvium SAND, some gravel, some silt (SP-SM) 5.5 EB-2 2.5 Fill Silty SAND, some gravel (SM) 23.2 EB-3W 2.5 Fill Silty SAND, some gravel (SM) 24.7 EB-3W 7.5 Black River Alluvium Very silty SAND, trace gravel (SM) 37.6 EB-4 0 Fill Very gravelly, silty, SAND (SM) 13.5 EB-5 10 Black River Alluvium Silty SAND (SM) 17.6 EB-6W 15 Cedar River Alluvium Very sandy GRAVEL, some silt (GP-GM) 5.7 USCS = Unified Soil Classification System Fines Content % = percent of total weight passing the U.S. No. 200 Sieve Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Critical Areas September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 13 II. GEOLOGIC HAZARDS AND CRITICAL AREAS The following discussion of potential geologic hazards and critical areas at the site and vicinity is based on the geologic conditions as observed and discussed herein. 5.0 LANDSLIDE HAZARDS AND MITIGATIONS Topography across the subject site and surrounding area is relatively flat to very gently sloping to the northwest. Overall vertical relief across the school campus trending south to north is approximately 4 feet over a distance of about 850 feet. We did not identify any steep slopes within the project site or vicinity. Due to the relatively flat topography across the project site and the lack of any sloping areas in the site vicinity, it is our opinion that the risk of landsliding affecting the school campus and adjacent properties is very low and that no mitigation measures are necessary for this project. 6.0 SEISMIC HAZARDS AND MITIGATIONS The following discussion is a general assessment of seismic hazards that is intended to be useful to the project design team in terms of understanding seismic issues, and to the structural engineer for design. All of Western Washington is at risk of strong seismic events resulting from movement of the tectonic plates associated with the Cascadia Subduction Zone (CSZ), where the offshore Juan de Fuca plate subducts beneath the continental North American plate. The site lies within a zone of strong potential shaking from subduction zone earthquakes associated with the CSZ. The CSZ can produce earthquakes up to magnitude 9.0, and the recurrence interval is estimated to be on the order of 500 years. Geologists infer the most recent subduction zone earthquake occurred in 1700 (Goldfinger et al., 20121). Three main types of earthquakes are typically associated with subduction zone environments: crustal, intraplate, and interplate earthquakes. Seismic records in the Puget Sound region document a distinct zone of shallow crustal seismicity (e.g., the Seattle Fault Zone [SFZ]). These shallow fault zones may include surficial expressions of previous seismic events, such as fault scarps, displaced shorelines, and shallow bedrock exposures. The shallow fault zones typically extend from the surface to depths ranging from 16 to 19 miles. A deeper zone of seismicity is associated with the subducting Juan de Fuca plate. Subduction zone seismic events produce intraplate earthquakes at depths ranging from 25 to 45 miles beneath the Puget Lowland including the 1949, 7.2-magnitude event; the 1965, 6.5-magnitude event; and the 2001, 1 Goldfinger, C., Nelson, C.H., Morey, A.E., Johnson, J.E., Patton, J.R., Karabanov, E., Gutierrez-Pastor, J., Eriksson, A.T., Gracia, E., Dunhill, G., Enkin, R.J., Dallimore, A., and Vallier, T., 2012, Turbidite Event History—Methods and Implications for Holocene Paleoseismicity of the Cascadia Subduction Zone: U.S. Geological Survey Professional Paper 1661–F, 170. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Critical Areas September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 14 6.8-magnitude event) and interplate earthquakes at shallow depths near the Washington coast including the 1700 earthquake, which had a magnitude of approximately 9.0. The 1949 earthquake appears to have been the largest in this region during recorded history and was centered in the Olympia area. Evaluation of earthquake return rates indicates that an earthquake of the magnitude between 5.5 and 6.0 is likely within a given 20-year period. Generally, there are four types of potential geologic hazards associated with large seismic events: 1) surficial ground rupture, 2) seismically induced landslides or lateral spreading, 3) liquefaction, and 4) ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. 6.1 Surficial Ground Rupture Seattle Fault Zone The site is located approximately 3 miles south of the mapped limits of the SFZ. The SFZ is a broad east-west oriented zone that extends from approximately Issaquah to Alki Beach and is approximately 2.5 to 4 miles in width from north to south. The SFZ is speculated to contain multiple distinct fault “strands,” some of which are well understood and some of which may be poorly understood or unknown. Mapping of individual fault strands is imprecise, as a result of pervasive modification of the land surface by development, which has obscured possible surficial expression of past seismic events. Studies by the U.S. Geological Survey (USGS) and others have provided evidence of surficial ground rupture along strands of the Seattle Fault (USGS, 20102; Pratt et al., 20153; Haugerud, 20054; Liberty et al., 20085). According to USGS studies the latest movement of this fault was about 1,100 years ago when about 20 feet of surficial displacement took place. This displacement can presently be seen in the form of raised, wave-cut beach terraces along Alki Point in West Seattle and Restoration Point at the south end of Bainbridge Island. Based on our review of the Washington State Department of Natural Resources (WADNR) website, inferred fault traces associated with the SFZ are located about 3 miles north of the site. Existing fault studies in the project area are insufficient to draw strong conclusions regarding seismic surface rupture potential at the project site. Due to the fact that the nearest mapped potential fault traces are located approximately 3 miles away from the site, and due to the suspected recurrence interval of seismic events along the SFZ, the potential for seismic surface rupture at the site is considered to be low during the expected life of the proposed structures, in our opinion. 2 U.S. Geological Survey, 2010, Quaternary Fault and Fold Database for the United States, accessed November 10, 2010, from USGS web site: http://earthquake.usgs.gov/hazards/qfaults/. 3 Pratt et al., 2015, Kinematics of Shallow Backthrusts in the Seattle Fault Zone, Washington State: Geosphere, v. 11, no. 6, p. 1-27). 4 Haugerud, R.A., 2005, Preliminary Geologic Map of Bainbridge Island, Washington: U.S. Geological Survey Open-File Report 2005-1387, version 1.0, 1 sheet, scale 1:24,000. 5 Liberty, Lee M.; Pratt, Thomas L., 2008, Structure of the Eastern Seattle Fault Zone, Washington State - New insights from Seismic Reflection Data: Bulletin of the Seismological Society of America, v. 98, no. 4, p. 1681-1695. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Critical Areas September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 15 6.2 Seismically Induced Landslides It is our opinion that the potential risk of damage to the proposed development by seismically induced slope failures is low during a design-level seismic event due to the lack of slopes at the project site and vicinity. No detailed slope stability analysis was completed for this project, and none is warranted, in our opinion. 6.3 Liquefaction Liquefaction is a process through which unconsolidated soil loses strength as a result of vibrations, such as those which occur during a seismic event. During normal conditions, the weight of the soil is supported by both grain-to-grain contacts and by the fluid pressure within the pore spaces of the soil below the water table. Extreme vibratory shaking can disrupt the grain-to-grain contact, increase the pore pressure, and result in a temporary decrease in soil shear strength. The soil is said to be liquefied when nearly all of the weight of the soil is supported by pore pressure alone. Liquefaction can result in deformation of the sediment and settlement of overlying structures. Areas most susceptible to liquefaction include those areas underlain by very soft to stiff, non-cohesive silt and very loose to medium dense, non-silty to silty sands with low relative densities, accompanied by a shallow water table. To evaluate the extent of liquefaction risk and estimated settlement potential during a design-level seismic event, we performed a liquefaction hazard analysis utilizing data obtained from our exploration borings and CPTs. Our liquefaction analysis was completed with the aid of LiquefyPro computer software Version 5.9a (2015) by CivilTech Corporation. This program accepts input for SPT and CPT data, groundwater levels, soil unit weight, and the depth and grain-size distribution of the sediments of concern to calculate seismically induced settlement. The following parameters were used during the analysis: We assumed a seasonal high groundwater level of 5 feet below the existing ground surface during earthquake shaking; Soil unit weights were inferred from SPT and CPT data; Silt contents were inferred from CPT data and a combination of visual and laboratory classification of soil samples obtained from the SPT borings; CPT data were automatically normalized for overburden stresses and corrected for fines content and seismic magnitude by the LiquefyPro computer software; We used the Tokimatsu M-Correction analysis method in the LiquefyPro computer software to obtain the liquefaction-induced settlement values; A design event is considered a magnitude 7.0 earthquake with a peak horizontal ground acceleration of 0.677g as determined from the ASCE Hazard Tool website at https://ascehazardtool.org. The results of the liquefaction analysis indicate that the Black River alluvium and Cedar River alluvium are susceptible to liquefaction to a depth of about 40 feet and are predicted to Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Critical Areas September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 16 experience significant amounts of liquefaction-induced settlement during a design-level seismic event. Although Cedar River alluvium was encountered below a depth of 40 feet in all exploration borings, we assess that the liquefaction potential is low below this depth as the drill rig auger “refused” at a depth of about 45 to 50 feet at all locations, indicating the presence of large gravels/cobbles that would be considered non-liquefiable or the contact of a very dense geologic unit. This assessment is further supported by the shear wave velocity data obtained by the WGS (see Appendix G), where the measured shear wave velocities below a depth of 40 feet exceeded 1,200 feet per second, which corresponds to “very dense soil and soft rock” per ASCE 7-16 Table 20.3-1 “Site Classification.” The liquefaction-induced settlement calculated based on SPT data ranged from about 2 to 11 inches (with an average of 6 to 7 inches), and the magnitude of predicted settlement generally increased across the site trending south to north. We assess this trend in predicted settlement is correlated to the thickness of the Black River alluvium. As the thickness of the loose/soft Black River alluvial sediments “pinch out” toward the south end of the site, the magnitude of liquefaction-induced settlement decreases, suggesting that the magnitude of liquefaction- induced settlement can be expected to increase to the north. It should be noted that the magnitude of predicted settlements based on CPT data is significantly less than results based on SPT data. We attribute this discrepancy to the following: (1) the CPT- based analysis did not consider some of the gravelly layers liquefiable as the measured cone resistance was overstated and (2) soft silt layers within the Black River alluvium unit were correlated to a non-liquefiable clay. It is our opinion that the liquefaction analysis results based on SPT data are more representative of the subsurface conditions and liquefaction potential at the site. The results of our liquefaction analysis at individual exploration locations are summarized in Table 4 and details are presented in Appendix F. Table 4 Estimated Total Liquefaction-Induced Settlement Exploration Number Estimated Total Liquefaction-Induced Settlement (inches) EB-1W 11 EB-2 7 EB-3W 7 EB-4 7 EB-5 4 EB-6W 2 CPT-01 1.8 CPT-02 0.9 CPT-03 1.4 Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Critical Areas September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 17 Based on the results of the liquefaction analysis summarized above, it is our opinion that liquefaction mitigation measures are warranted for this project. Our design recommendations for ground improvement to mitigate liquefaction-induced settlement hazards are presented below in the “Foundations” section of this report. 6.4 Ground Motion/Seismic Site Class Based on the subsurface stratigraphy and visual reconnaissance of the site, it is our opinion that earthquake damage to the proposed structures when founded on suitable bearing strata in accordance with the recommendations contained herein, would likely be caused by the intensity and acceleration associated with the event. We understand that structural design for the project will follow the 2021 International Building Code (IBC) standards and the American Society of Civil Engineers Publication ASCE 7-16 Minimum Design Loads and Associated Criteria for Buildings and Other Structures. ASCE 7-16 allows a simplified procedure for determining site class for those projects where liquefiable-prone soils are present and the fundamental period of the planned building is 0.5 seconds or less. The simplified procedure allows the site class to be determined based on the average N-value and/or average shear wave velocity within the upper 100 feet of the site as outlined in ASCE 7-16 Section 20.3. If the fundamental period is greater than 0.5 seconds, we will need to perform a site-specific response analysis in accordance with ASCE 7-16, Sections 20.3.1 and 21.1. We are available to perform this analysis and reporting under a separate scope of work when a developed site plan is selected that includes building locations and heights. For proposed structures that will have a building period of less than 0.5 seconds, we recommend using Site Class D for structural design based on the subsurface conditions encountered in our exploration borings and the shear wave velocity data obtained by the WGS (as discussed below). As previously mentioned, the WGS conducted a seismic survey at the project site on October 15, 2020. The seismic survey was completed with an array of 48 geophones placed in a 308-foot line to measure the shear wave velocity within the upper 100 feet of soil. This array was located to the west of the existing school buildings in the existing ballfield. The average shear wave velocity within the upper 100 feet of the array was approximately 892 feet per second, which corresponds to Site Class D. The shear wave velocity results are included in Appendix G. 7.0 EROSION HAZARDS AND MITIGATIONS Erosion Hazards are defined in the Renton Municipal Code (RMC) Section 4-3-050G.5.c. as the following: Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Critical Areas September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 18 i. Low Erosion Hazard (EL): Areas with soils characterized by the Natural Resource Conservation Service (formerly U.S. Soil Conservation Service) as having slight or moderate erosion potential, and a slope less than fifteen percent (15%). ii. High Erosion Hazard (EH): Areas with soils characterized by the Natural Resource Conservation Service (formerly U.S. Soil Conservation Service) as having severe or very severe erosion potential, and a slope more than fifteen percent (15%). Based on our review of the City of Renton “Sensitive Areas Map: Erosion Hazard,” the subject site is not mapped as an erosion hazard area. As stated in the “Regional Geologic and Soils Mapping” section of this report, the site is identified as Urban Land. The NRCS indicates that the erosion hazard rating for Urban Land soils is slight to moderate. Due to the lack of slopes at the site and the erosion hazard rating of slight to moderate for on-site material, the subject site classifies as a Low Erosion Hazard according to the RMC. Despite being identified as a Low Erosion Hazard, the existing fill and underlying native alluvial sediments at the site generally contain significant quantities of silt and fine sand. These sediments will be susceptible to erosion and off-site sediment transport when exposed during construction. Therefore, the project should follow best management practices (BMPs) to mitigate erosion hazards and potential for off-site sediment transport. The Washington State Department of Ecology (Ecology) Construction Stormwater General Permit (also known as the National Pollutant Discharge Elimination System [NPDES] permit) requires weekly Temporary Erosion and Sedimentation Control (TESC) inspections and turbidity monitoring of site runoff for all sites that are 1 or more acres in size that discharge stormwater to surface waters of the state. The TESC inspections and turbidity monitoring of runoff must be completed by a Certified Erosion and Sediment Control Lead (CESCL) for the duration of the construction. Requirements for inspections, sampling, and reporting can be found in the Construction Stormwater General Permit online at ecology.wa.gov. In order to meet the current Ecology requirements, a properly developed, constructed, and maintained erosion control plan consistent with local standards and best management erosion control practices will be required for this project. It is often necessary to make adjustments and provide additional measures to the TESC plan in order to improve its effectiveness. Ultimately, the success of the TESC plan depends on a proactive approach to project planning and contractor implementation and maintenance. To mitigate and reduce the erosion hazard and potential for off-site sediment transport, we recommend the following: 1. Construction activity should be scheduled or phased as much as possible to avoid earthwork activity during the wet season. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Critical Areas September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 19 2. The winter performance of a site is dependent on a well-conceived plan for control of site erosion and stormwater runoff. The site plan should include ground-cover measures and staging areas. The contractor should be prepared to implement and maintain the required measures to reduce the amount of exposed ground. 3. TESC elements and perimeter flow control should be established prior to the start of grading. This should include, but is not limited to, silt fencing, swales with check dams, rocked construction entrance, etc. 4. During the wetter months of the year, or when significant storm events are predicted during the summer months, the work area should be stabilized so that if showers occur, it can receive the rainfall without excessive erosion or sediment transport. The required measures for an area to be “buttoned-up” will depend on the time of year and the duration that the area will be left unworked. During the winter months, areas that are to be left unworked for more than 2 days should be mulched or covered with plastic. During the summer months, stabilization will usually consist of seal-rolling the subgrade. Such measures will aid in the contractor’s ability to get back into a work area after a storm event. The stabilization process also includes establishing temporary stormwater conveyance channels through work areas to route runoff to the approved treatment/discharge facilities. 5. Surface runoff and discharge should be controlled during and following development. Uncontrolled discharge may promote erosion and sediment transport. 6. Soils that are to be reused around the site should be stored in such a manner as to reduce erosion from the stockpile. Protective measures may include, but are not limited to, covering stockpiles with plastic sheeting, or the use of silt fences around stockpile perimeters. It is our opinion that with the proper implementation of the TESC plans and by field-adjusting appropriate erosion mitigation (BMPs) throughout construction, the potential adverse impacts from erosion hazards on the project may be mitigated. 8.0 CRITICAL AQUIFER RECHARGE AREAS Based on our review of the City of Renton’s Water System Plan Update, A Comprehensive Water System Plan (May 2021), which is the guiding document for the aquifer protection zone mapping and regulations, Section 6.10 “Wellhead Protection Program” states the following: Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Critical Areas September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 20 “As part of its Aquifer Protection Program, the City has enacted aquifer protection regulations within the Aquifer Protection Areas (APAs) to protect the aquifers used as potable water supply sources from contamination by hazardous materials. The regulations include restrictions on hazardous material quantities, storage, and handling; land use restrictions; facility operating standards; construction activity standards; fill quality standards; and other measures intended to prevent contamination.” Based on our review of the City of Renton interactive online GIS mapping tool6, the existing high school campus and proposed expansion is located within a Wellhead Protection Area (WHPA). The GIS mapping indicates that the approximate eastern half of the school campus and proposed improvements are located within a Zone 1 WHPA and the approximate western half of the school campus and proposed improvements are located within a Zone 2 WHPA. The GIS mapping of the Zones 1 and 2 WHPAs relative to the school campus and proposed expansion is presented in Appendix H. Section 4-3-050G.8 of the RMC defines WHPAs as follows: 8. Wellhead Protection Areas: a. Applicability: Developments, facilities, uses and activities discussed in this subsection shall comply with the applicable provisions and restrictions of this Section and chapters 4-4, 4-5, 4-6, 4-9, and 5-5 RMC for the Wellhead Protection Areas, as classified below, in which the developments, facilities, uses and activities are located, except as preempted by Federal or State law. i. Wellhead Protection Areas: Wellhead Protection Areas are the portion of an aquifer within the zone of capture and recharge area for a well or well field owned or operated by the City. ii. Wellhead Protection Area Zones: Zones of a Wellhead Protection Area are designated to provide graduated levels of Wellhead Protection Area recharge. Zone boundaries are determined using best available science documented in the City of Renton Wellhead Protection Plan, an appendix of the City of Renton Water System Plan, as periodically updated. The following zones may be designated: (a) Zone 1: The land area situated between a well or well field owned by the City and the three hundred sixty five (365) day groundwater travel time contour. (b) Zone 1 Modified: The same land area described for Zone 1 but for the purpose of protecting a high-priority well, wellfield, or spring withdrawing from a confined aquifer with partial leakage in the overlying or underlying confining layers. Uses, activities, and facilities located in this area are regulated as if located within Zone 1 except as provided by this subsection G8. (c) Zone 2: The land area situated between the three hundred sixty five (365) day groundwater travel time contour and the boundary of the zone of potential capture for a well or well field owned or operated by the City. If the aquifer supplying water to such a well, well field, or spring is naturally protected by confining overlying and underlying geologic layers, the City may choose not to subdivide a Wellhead Protection Area into two (2) zones. In such a case, the entire Wellhead Protection Area will be designated as Zone 2. 6 https://www.rentonwa.gov/Projects-Development/Maps-and-GIS-Data Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Critical Areas September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 21 RMC Section 4-8-120 lists the submittal requirements for each type of permit application or land use approval, and RMC Section 4-8-120D, Table 18, lists the geotechnical reporting requirements for projects located within a regulated shoreline area, which includes sites located within WHPAs. The geotechnical reporting requirements contained in Table 18 that have not already been addressed in other sections of this report are provided below in italics along with our responses. Note that we have used the same name numbering scheme for the list of reporting requirements as Table 18. 4. Characterize groundwater conditions including the presence of any public or private wells within one- quarter (1/4) mile of the site. Groundwater conditions at the site are described in the “Hydrology” section of this report. AESI reviewed available information on WHPAs for Group A and Group B water systems located within ¼ mile of the subject site. Based on mapping by the Washington State Department of Health (DOH) Source Water Assessment Program (SWAP) application7, an inactive Group B well is located about 350 feet west of the western property line. No other wells were mapped within ¼ mile of the subject site. Based on our review of the Washington State Department of Ecology Well Construction & Licensing Map Search8, no water supply wells are located within ¼ mile of the subject site. 19. Address factors specific to the site, or to the proposed shoreline modification, as required in RMC 4-3- 090, Shoreline Master Program Regulations. RMC 4-3-090 is specific to shorelines of the State and does not directly address WHPAs; however, this section references RMC 4-3-050 which has been previously discussed above. Based on our review of the RMC and the City’s comprehensive water system plan, the following key items should be noted for this project: Stormwater infiltration is not allowed in a Zone 1 WHPA. Limitations apply to the conveyance, detention, and water quality of stormwater facilities to prevent infiltration. Liners may be required. Construction activity policies must be established for onsite re-fueling along with action plans/documentation protocols for incidents related to leaking fuel, hydraulic fluid, etc. Fill quality standards will apply to earthwork during construction. An imported fill source statement is required if more than 50 cubic yards (Zone 1) or 100 cubic yards (Zone 2) of imported fill will be brought to the site. 7 https://fortress.wa.gov/doh/swap/index.html 8 https://appswr.ecology.wa.gov/WellConstruction/ Map/WCLSWebMap/WellConstructionMapSearch.aspx Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Geologic Hazards and Critical Areas September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 22 In summary, based on known subsurface conditions and the current development plans, there are no indications that long-term groundwater levels or groundwater quality will be adversely impacted by the proposed high school replacement and expansion, provided the development utilizes modern stormwater management controls (BMPs) during construction and final development and City of Renton requirements for development in aquifer protection areas. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 23 III. DESIGN RECOMMENDATIONS 9.0 INTRODUCTION Our explorations indicate that, from a geotechnical engineering standpoint, the project is feasible provided the recommendations in this report are properly incorporated during design and construction. The explorations completed for this study indicate that the footprint of the school campus replacement contains a variable thickness of existing fill overlying loose to medium dense alluvial sediments accompanied by a shallow water table. Existing fill is not suitable for foundation support and warrants remedial preparation below pavements and flat work. The near-surface alluvial deposits are susceptible to liquefaction and will require mitigation measures for building foundation support. Based on explorations and analyses completed to date, we have identified the following geotechnical considerations that will impact design and construction of the project: Our liquefaction analysis predicts that the site may experience up to 11 inches of settlement during a design-level earthquake event, primarily due to liquefaction-induced settlement of the loose to medium dense alluvial sediments that extend to a depth of about 40 feet. This magnitude of settlement will require liquefaction mitigation measures such as ground improvement or a deep foundation system. Groundwater was encountered at depths ranging from about 9.5 to 14 feet at the time of our explorations. Our explorations for this study were conducted in April when groundwater levels are typically elevated but not at seasonal high levels. Previous explorations at the site have indicated groundwater levels as shallow as 4.5 feet at the time of drilling in early March. Depending on the time of construction, significant dewatering efforts may be required to control groundwater flow into excavations for utilities or other facilities deeper than about 5 feet. The following sections provide our recommendations for site preparation and earthwork, temporary cut slopes, structural fill, building foundations, floor support, drainage considerations, pavements, and infiltration feasibility. 10.0 SITE PREPARATION Prior to site work, erosion and surface water control should be established around the perimeter of the site to satisfy City of Renton and Ecology requirements, as discussed in the “Erosion Hazards and Mitigations” section of this report. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 24 10.1 Well Decommissioning Prior to construction, any wells that are located within the footprint of planned improvements (e.g., buildings, pavements, hardscapes, utilities, and athletic fields), or any wells that are no longer needed for groundwater level monitoring, should be decommissioned by a licensed well driller in accordance with Washington Administrative Code (WAC) 173-160-381. 10.2 Clearing and Stripping Existing buildings, foundations, pavements, buried utilities, vegetation, topsoil, and any other deleterious materials should be removed where they are located below planned construction areas. Any disturbed soils or depressions, such as those that may be caused by demolition activities, below planned final grades should be compacted with a smooth-drum vibratory roller to at least 95 percent of the modified Proctor maximum dry density as determined by the ASTM D-1557 test procedure, and to a firm and unyielding surface. Structural fill should be placed as needed to restore planned grades as discussed under the “Structural Fill” section of this report. Where excavated existing fill and native sediments are free of organics and near their optimum moisture content for compaction they can be segregated and considered for reuse as structural fill if allowed by project specifications. Most of the native sediments encountered in our explorations contained significant silt fractions and are considered highly moisture-sensitive; these soils may be difficult to reuse as structural fill. 10.3 Existing Fill After demolition, clearing, stripping, and any planned excavations have been completed, existing fill should be addressed within areas of planned paving and hardscapes. The existing fill should be exposed, compacted, and proof-rolled under the observation of AESI. Any areas that are soft, yielding, or contain excessive organic material or demolition waste should be corrected as needed prior to paving. 10.4 Temporary Cut Slopes In our opinion, stable construction slopes should be the responsibility of the contractor and should be determined during construction based on the conditions encountered at that time. For estimating purposes, however, we anticipate that temporary, unsupported cut slopes in unsaturated existing fill and native alluvial soils can be planned at inclinations of 1.5H:1V (Horizontal:Vertical) or flatter. Excavations below the groundwater table into saturated sediments should not be attempted without proper dewatering measures in place. Permanent cut or structural fill slopes should not be steeper than 2H:1V. Permanent slopes that will be exposed to surface water should be inclined at 3H:1V or flatter. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 25 These slope angles are for areas where groundwater seepage is not encountered and assume that surface water is not allowed to flow across the temporary slope faces. As is typical with earthwork operations, some sloughing and raveling may occur, and cut slopes may have to be adjusted in the field. In addition, WISHA/OSHA regulations should be followed at all times. 10.5 Site Disturbance The existing fill and native sediments contain a high percentage of fine-grained material. These sediments are considered to be highly moisture-sensitive and subject to disturbance when wet. The contractor must use care during site preparation and excavation operations so that the underlying soils are not softened. If disturbance occurs, the softened soils should be removed and the area brought to grade with structural fill. 10.6 Wet Weather Considerations The on-site soils are considered to be highly moisture-sensitive. If construction takes place in, during, or immediately following the wetter periods of the year, we anticipate the on-site soils will become unsuitable for structural fill applications. If earthwork will be completed during wet season months, we recommend budgeting to construct all structural fills with select, imported fill materials. For construction immediately following wet periods, significant, but unavoidable effort will be needed to scarify, aerate, and dry site soils to reduce moisture content prior to compaction in structural fill applications. Care should be taken to seal all earthwork areas during mass grading at the end of each workday by grading all surfaces to drain and sealing them with a smooth-drum roller. Stockpiled soils that will be reused in structural fill applications should be covered whenever rain is possible. Construction during extended wet weather periods could create the need to overexcavate exposed soils if they become disturbed and cannot be recompacted due to elevated moisture content and/or weather conditions. Even during dry weather periods, soft/wet soils may be encountered in some portions of the site that will require overexcavation. If overexcavation is necessary, it should be confirmed through continuous observation and testing by AESI. Soils that have become unstable may require remedial measures in the form of one or more of the following: 1. Drying and recompaction. Selective drying may be accomplished by scarifying or windrowing surficial material during extended periods of dry and warm weather. 2. Removal of affected soils to expose a suitable bearing subgrade and replacement with compacted structural fill. 3. Mechanical stabilization with a coarse crushed aggregate compacted into the subgrade, possibly in conjunction with a geotextile. 4. Soil/cement admixture stabilization. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 26 Consideration should be given to protecting access and staging areas with an appropriate section of crushed rock or asphalt treated base (ATB). If crushed rock is considered for the access and staging areas, it should be underlain by engineering stabilization fabric (such as Mirafi 500X or approved equivalent) to reduce the potential of fine-grained materials pumping up through the rock during wet weather and turning the area to mud. The fabric will also aid in supporting construction equipment, thus reducing the amount of crushed rock required. We recommend that at least 10 inches of rock be placed over the fabric. Crushed rock used for access and staging areas should be of at least 2-inch size. 11.0 STRUCTURAL FILL All new structural fill should be placed and compacted according to the recommendations presented in this section and requirements included in project specifications. All references to structural fill in this report refer to subgrade preparation, fill type, placement, and compaction of materials, as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. 11.1 Subgrade Compaction After clearing, stripping, and existing fill replacement have been completed in accordance with the “Site Preparation” section of this report, the upper 12 inches of exposed ground should be recompacted to a firm and unyielding condition. If the subgrade contains too much moisture, suitable recompaction may be difficult or impossible to attain and should probably not be attempted. In lieu of recompaction, the area to receive fill should be blanketed with washed rock or quarry spalls to act as a capillary break between the new fill and the wet subgrade. Where the exposed ground remains soft and further overexcavation is impractical, placement of an engineering stabilization fabric may be necessary to prevent contamination of the free-draining layer by silt migration from below. After recompaction of the exposed ground is tested and approved, or a free-draining rock course is laid, structural fill may be placed to attain desired grades. 11.2 Structural Fill Compaction Structural fill is defined as non-organic soil compliant with project specifications, placed in maximum 8-inch loose lifts, with each lift being compacted to at least 95 percent of the modified Proctor maximum dry density using ASTM D-1557 as the standard. The top of the compacted fill should extend horizontally a minimum distance of 3 feet beyond footings before sloping down at an angle no steeper than 2H:1V. Fill slopes should either be overbuilt and trimmed back to final grade or surface-compacted to the specified density. In the case of roadway and utility trench filling, the backfill should be placed and compacted in accordance with City of Renton standards. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 27 11.3 Use of On-Site Soils as Structural Fill Soils in which the amount of fine-grained material (smaller than No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered moisture-sensitive. Most of the existing fill and near-surface native sediments encountered in our explorations contained significant silt fractions and are considered highly moisture-sensitive; these soils may be difficult to reuse as structural fill. Additionally, construction equipment traversing the site when the silty native sediments are very moist or wet can cause considerable disturbance. During the wetter portion of the year, typically from October to June, we recommend assuming that the on-site soils will not be suitable for reuse in structural fill applications. Possible alternatives would include cement treating on-site soils or using only a select import material consisting of a clean, free-draining gravel and/or sand. Free-draining fill consists of non-organic soil with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction. 11.4 Structural Fill Testing The contractor should note that any proposed fill soils must be evaluated by AESI prior to their use in fills. This would involve providing us with a sample of the material at least 3 business days in advance to perform a Proctor test to determine its field compaction standard. A representative from our firm should observe the subgrades and be present during placement of structural fill to observe and document the work and perform a representative number of in-place density tests. In this way, the adequacy of the earthwork may be evaluated as filling progresses and any problem areas may be corrected at that time. Such testing and observation may be required by the City of Renton. 12.0 FOUNDATIONS Based on our review of the conceptual site plan, we understand that the campus replacement will include new school buildings surrounding the Performing Arts Center within the southeast corner of the campus. We anticipate that the foundation bearing soils within the proposed building footprints will generally be comprised of existing fill underlain by Black River and Cedar River alluvium. The alluvium within this current footprint of the new school buildings is predicted to experience liquefaction during a design-level seismic event, potentially resulting in average post-liquefaction total settlements on the order of 7 inches and differential settlements on the order of 5 inches. Given these conditions, it is our opinion that the existing site soils below the planned buildings are not suitable for the direct support of conventional shallow foundations. Additionally, we anticipate that the loose/soft alluvial sediments will result in excessive post-construction settlements under static loading. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 28 Due to the liquefaction hazards at the site, we recommend that buildings be supported on either shallow foundations utilizing ground improvement measures or deep foundations to mitigate excessive static settlement and differential liquefaction-induced settlement. Since ground improvement mitigates liquefaction hazards and is typically more economical than deep foundations, we consider shallow foundations with ground improvement to be the most cost-effective approach for this project. A ground improvement program consisting of vibratory stone columns or rammed aggregate piers (RAPs) is recommended to provide building foundation and slab-on-grade support. The ground improvement system would be designed by the ground improvement contractor to mitigate both static and seismic liquefaction settlements, and limit post-liquefaction differential settlements to structural design requirements. Subsequent to completion of the ground improvement program, the building could be supported using conventional spread footing foundations. The ground improvement contractor in conjunction with the project structural engineer should provide the final spacing, depths, and diameters of the RAPs. For project planning purposes, shallow foundations bearing on properly completed RAPs can typically be designed for an allowable soil bearing pressure ranging from 4,000 to 6,000 pounds per square foot (psf). Based on our initial discussions with the project team, we anticipate that RAPs will be spaced at approximate 6-foot centers below footings. The array of RAPs should maintain a minimum horizontal distance of 15 feet from the edge of any existing buildings to mitigate potential vibration-induced distresses on sensitive building elements. A vibration monitoring program should be established prior to construction in coordination with AESI. Given the magnitude of predicted liquefaction-induced settlement across the site (average total settlement of 7 inches and differential settlements on the order of 5 inches), we recommend that RAPs also be incorporated into the slab-on-grade design. We anticipate that RAPs below interior slabs would be spaced at approximate 8- to 10-foot centers. If significant damage and loss of functionality of interior slabs during an earthquake event is deemed acceptable by the District, a typical slab-on-grade could be used (4- to 6-inch concrete slab supported on a capillary break layer with vapor barrier); however, remediation of the loose existing fill soils will be required to mitigate static settlement. Remedial measures of existing fill would involve up to 2 feet of overexcavation and replacement with select imported structural fill or crushed rock. Overexcavation activities may result in archeological findings which could have a significant impact on the project schedule and overall construction costs. In our opinion, there is no benefit to thickening the slab-on-grade or adding additional reinforcement if seismic performance is not required for the project; the slab would still likely experience substantial settlement, cracking, and loss of functionality. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 29 If structural loading exceeds the typical range of allowable soil bearing pressures for RAP-supported foundations, or if predicted foundation settlements cannot be limited to structural design requirements, a deep foundation system will be required for this project. Deep foundation systems commonly used in the Puget Sound area include augercast piles, drilled shafts, micropiles, and driven steel pipe piles. We understand that the project structural engineer, PCS Structural Solutions (PCS), is planning to utilize augercast piles for the portion of the new school building that is adjacent to the 1 930’s historical building, and that micropiles will be used for interior support of the 1930’s historical building. Our design recommendations for augercast piles and micropiles are provided further below in Sections 12.3 and 12.4. 12.1 Spread and Strip Footings on Rammed Aggregate Piers For footings founded directly upon properly completed RAPs, we recommend that an allowable bearing pressure of 4,000 psf be used for design purposes, including both dead and live loads. An increase in the allowable bearing pressure of one-third may be used for short-term wind or seismic loading. Perimeter footings should be buried at least 18 inches into the surrounding soil for frost protection. However, all foundations must bear directly on properly completed RAPs, and no foundations should be constructed in or above soft/loose, organic, or existing fill soils. Anticipated static settlement of footings founded on RAPs as recommended should be less than 1 inch with differential settlement one-half of the anticipated total settlement. Most of this movement should occur during initial dead load applications. However, disturbed material not removed from footing trenches prior to footing placement could result in increased settlements. Seismic performance and liquefaction-induced settlement tolerances of RAP-supported foundations and slabs-on-grade should be established by the structural engineer in coordination with AESI and the specialty design contractor. All footing areas should be inspected by AESI prior to placing concrete to verify that the RAPs are in the proper location, and construction conforms to the recommendations contained in this report. Foundation bearing verification will likely also be required by the municipality. Perimeter footing drains should be provided as discussed under the “Drainage Considerations” section of this report. It should be noted that the area bounded by lines extending downward at 1H:1V from any footing must not intersect another footing or intersect a filled area that has not been compacted to at least 95 percent of ASTM D-1557. If structural fill is placed below footing areas, the structural fill should extend horizontally beyond the footing by at least 1 foot. If new foundations are to be installed near existing buildings or structures, the footings should be the same depth to avoid surcharging or undercutting the existing foundations. In addition, a 1.5H:1V line extending down and away from any footing must not daylight because sloughing or raveling may eventually Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 30 undermine the footing. Thus, footings should not be placed near the edges of steps or cuts in the bearing soils. 12.2 Passive Resistance and Friction Factors Lateral loads can be resisted by friction between the foundation and the natural soils or supporting structural fill soils, and by passive earth pressure acting on the buried portions of the foundations. The foundations must be backfilled with structural fill and compacted to at least 95 percent of the maximum dry density to achieve the passive resistance design values recommended below. We recommend the following allowable design parameters which include a factor of safety of 1.5: Passive equivalent fluid = 250 pounds per cubic foot (pcf) Coefficient of friction = 0.30 The passive value presented above assumes an equivalent triangular fluid pressure distribution beginning at the surface. The triangular pressure distribution and resulting passive resistance should be truncated (ignored) to a depth of 2 feet from the ground surface. 12.3 Augercast Piles Based on information provided by PCS, we understand that augercast piles are planned to support the portion of the new school building that will be adjacent to the Performing Arts Center building. PCS is currently considering the use of 16-inch or 18-inch-diameter piles. We understand that the augercast piles will support axial loads of approximately 30 kips and lateral loads up to 30 kips, and that lateral deflection of the piles should be limited to ½ inch. Based on the borings completed near this area, we anticipate that the piles will penetrate loose/soft Black River alluvium to a depth on the order of 25 feet underlain by medium dense Cedar River alluvium extending beyond a depth of 50 feet. Groundwater is anticipated to be encountered at depths as shallow as 10 feet below existing grade, but could vary depending on the time of year and seasonal precipitation. Ultimate soil strength capacities were analyzed using the computer program AllPile Version 7.21h by CivilTech Software. A summary of recommended pile embedment depths and allowable capacities for 16-inch and 18-inch-diameter augercast piles are provided in Table 5 below. We recommend the augercast piles be extended to a minimum depth of 50 feet to penetrate the medium dense Cedar River alluvium and to resist potential downdrag loads imposed on the piles due to settlement of the liquefiable layers above. The anticipated post-construction settlement of the augercast pile-supported foundations will generally be on the order of ½ inch or less. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 31 Table 5 Augercast Pile Minimum Embedment and Capacities Pile Diameter (inches) Minimum Pile Embedment Depth Below Existing Grade(1) (feet) Allowable Axial Compressive Resistance(2) (kips) Lateral Capacity for 0.5-inch Deflection Under Free Head Conditions (kips) Lateral Capacity for 0.5-inch Deflection Under Fixed Head Conditions (kips) 16 55 30 12 25 18 50 30 14 30 (1) The minimum embedment depth corresponds to at least 10 feet below potentially liquefiable alluvial soils based on our exploration data. Actual pile embedment depths should be determined during construction in coordination with AESI. (2) The allowable axial compressive resistance corresponds to a safety factor of 2.5 for tip resistance and 2.0 for side friction resistance, and accounts for downdrag loads associated with the potential 40-foot zone of liquefiable soils above. Lateral Reduction Factors Augercast piles with lateral spacing less than six (6) pile diameters from another pile along the direction of force should be considered to be in the zone of influence, and the lateral capacity and the reduction factors presented below in Table 6 should be used. Table 6 Lateral Reduction Factors Pile Spacing in Direction of Loading Reduction Factor 6 diameters 1.0 5 diameters 0.8 4 diameters 0.6 3 diameters 0.4 Augercast Pile Construction Observations Construction planning should include allowing sufficient time for the grout to cure before drilling nearby piles. Typically, 24 hours of set time is recommended for piles closer than three (3) pile diameters or 10 feet, whichever is greater. The actual length of each augercast pile may be adjusted in the field based on the required capacity and conditions encountered during drilling. Since augercast piles are advanced in a closed hole with a continuous flight auger and withdrawn with a head of grout, the judgment and experience of the geotechnical engineer or their field representative must be used to assess if drilling conditions and pile advancement agree with the anticipated subsurface conditions, and to confirm the grout volumes exceed the theoretical volume of the borehole. Therefore, we recommend that all piles be observed by a qualified geotechnical engineer or engineering geologist from our firm, who can interpret and collect installation data and review the contractor’s operations. A final summary report would be issued after the pile installation is completed. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 32 12.4 Micropiles Based on information provided by PCS, we understand that micropiles will be installed within the interior of the 1930’s historical building. We understand that the micropiles will provide support of vertical loads only, and that no lateral capacity is needed. Micropiles are drilled and grouted reinforced piles that can have diameters ranging from 4 to 12 inches. They are used mainly as pressure-grouted friction piles to resist both tension and compression loads but can also provide resistance to lateral loads. Micropiles are installed with relatively small drilling equipment, allowing installation under limited-access and low-headroom conditions. Local contractors typically install a 7- or 8-inch-diameter micropile and have historically used the pin pile system approach. The pin pile system uses an outer pipe casing to stabilize the drill hole and an inner drill rod for cleaning out the casing or drilling farther into harder ground. After reinforcement is placed (typically a #18 or #20 all-thread steel bar), the casing is pulled under constant pressure grouting and left partly in the ground as additional reinforcement and to prevent grout loss into ground with large voids. The pin piles are then post-grouted as needed to achieve design capacity. Vertical Micropile Capacities Based on the medium dense Cedar River alluvium encountered below an average depth of 25 feet in the vicinity of the 1930’s building, and assuming the use of an 8-inch-diameter pile casing and secondary pressure grouting techniques, the micropile can be sized assuming an allowable soil/grout bond strength of 1,500 psf in both tension and compression below a depth of 40 feet (corresponding to an ultimate bond strength of at least 3,000 psf using a safety factor of 2). We recommend ignoring the soil/grout bond strength within the potential liquefiable zone to a depth of 40 feet. We estimate that foundations supported on micropiles may experience a maximum total settlement of ½ inch or less. The allowable bond strength is applicable to the “load zone” of the micropile embedded into the medium dense Cedar River alluvium below a depth of 40 feet. A minimum 40-foot-deep “no-load zone” should be established from the bottom of the new pile cap. We recommend that the sacrificial casing be left in place within the no-load zone to a depth of 40 feet to reduce the potential downdrag loads imposed on the load-zone portion of the pile after an earthquake event. We recommend a minimum spacing of 5 feet center-to-center for micropiles. Micropile Verification Load Testing As mentioned above, we anticipate an ultimate bond strength of at least 3,000 psf can be achieved for micropiles installed into the medium dense Cedar River alluvium below a depth of 40 feet. This strength value should be verified through verification load testing. At least two (2) Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 33 micropiles should be tested in tension to 2 times the allowable micropile load. The load-test anchor can be part of the permanent foundation system. The load test can use the surrounding ground for a reaction to the tension loading. The load test is to verify that the allowable soil/grout bond strength has been achieved and has a safety factor of at least 2. AESI should be present during the verification load testing and during the installation of all production micropiles on this project. 12.5 Auxiliary Structures We understand that small auxiliary structures such as restrooms, concessions, and athletic storage buildings are planned to be supported on a thickened slab-on-grade (mat slab). Since these structures are lightly loaded and have a relatively small footprint, any liquefaction-induced settlement that may occur during an extreme earthquake event is anticipated to be relatively uniform across the building footprint, and the zone of unsaturated fill and shallow alluvium (at least 5 feet thick) overlying the liquefiable soils will mitigate loss of bearing capacity. Therefore, it is our opinion that mat slabs are suitable for support of auxiliary structures. We recommend using a maximum allowable bearing pressure of 1,500 psf for mat slab design. Given the high potential for encountering very loose/soft subgrade soils at shallow depths, we recommend planning for 2 to 3 feet of overexcavation and replacement with structural fill below the entire slab footprint that extends 2 to 3 feet beyond the perimeter. The overexcavation depth would be determined at the time of construction in coordination with AESI. If very loose/soft soil conditions are still present at a depth of 3 feet below the bottom of slab, we recommend placing a stabilization/separation fabric overlain by an 8- to 12-inch layer of 2-inch ballast rock to “bridge” the overlying structural fill. It should be noted that mat-slab supported auxiliary structures may not be functional after an extreme earthquake event, depending on the magnitude of liquefaction-induced settlement that manifests at the ground surface. 12.6 Significant Pole Foundations We anticipate that drilled shafts will be utilized to support significant pole structures such as football goal posts, foul ball posts, tall field light posts, flag poles, scoreboard lighting, etc. No structural loading information was available at the time of this report; however, based on our experience with similar athletic field lights, we anticipate that the light poles will be supported on either 30-inch or 36-inch-diameter drilled shaft foundations cast “neat” against the sidewalls of drilled holes without the use of forms. The football goal post may be supported by a rectangular cast-in-place concrete footing that is backfilled with structural fill. The pole foundations are anticipated to be embedded into highly variable fill soils underlain by loose/soft Black River alluvium. Our exploration borings indicate that the existing fill soils onsite could be up to 7 feet thick and in a very loose condition. Historical explorations indicate that groundwater across the site could be as shallow as 5 feet below existing grade. Given the high potential for encountering variable soil types, very loose/soft soil conditions, and shallow Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 34 groundwater across the site, we recommend assuming conservative soil parameters for pole foundation design. Our recommended soil parameters for determining lateral and axial capacities of the pole foundations are provided below. Lateral Capacity Lateral loads on significant pole foundations caused by transient wind loading conditions may be resisted by passive soil pressure against the side of the foundation. We recommend using a conservative allowable passive earth pressure of 200 pcf, expressed as an equivalent fluid unit weight, to a depth of 5 feet below grade. Below a depth of 5 feet, we recommend using a “submerged” passive earth pressure of 100 pcf to account for potential shallow groundwater conditions. These allowable values include a safety factor of 1.5. The above values only apply to foundation elements cast “neat” against undisturbed soil. The passive values presented should be applied as a triangular pressure distribution over twice the diameter of the foundation. The passive earth pressure should be neglected (truncated) to a depth of 2 feet below the ground surface and held at a constant value at a depth greater than 8 feet. Axial Capacity For this project, we assume that the lateral loads will be the most critical design factor for the light pole foundations and will control the depth of embedment; however, for design purposes, we recommend using an allowable end-bearing pressure of 1,500 psf for resisting axial loads. Additional vertical capacity can also be achieved through friction along the shafts, as described below. Frictional Resistance For frictional resistance along the drilled shaft, we recommend using a conservative allowable skin friction value of 200 psf for the full shaft length, excluding the uppermost 2 feet below the ground surface. Drilled Shaft Construction Recommendations The excavation equipment must be capable of maintaining a stable borehole with no caving while drilling into potentially very loose/soft soil conditions accompanied by a shallow water table. Depending on location-specific soil and groundwater conditions at the time of drilling, temporary casing may be required to prevent caving, and a sump pump may be needed to remove accumulated water from the base of the hole prior to placing concrete. The contractor should have the ability to excavate and remove debris or other obstacles that may be encountered within the existing fill during drilled shaft excavation. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 35 Alternative Analysis Options The soil parameters presented above are conservative to account for highly variable soil and groundwater conditions across a large area. AESI is available to analyze location-specific pole foundations upon request. It is possible that higher lateral capacities and/or shallower embedment depths could be achieved by completing a lateral load analysis using structural loading information provided by the design engineer and accounting for the bending moment resistance of the drilled shaft. 12.7 Site Signs and Sidewalk Light Posts Depending on the size and height of site signs and sidewalk light posts, wind loading could result in significant lateral forces. We recommend using the soil parameters provided in the “Significant Pole Foundations” section above in this case to determine the required diameter and embedment depth of the post foundation. AESI is available to review location-specific designs upon request. 12.8 Site Fences and Gates We recommend that fences and gates be installed in postholes that are at least 4 feet deep below the ground surface. For fences and gates that are not subject to significant wind loading, we recommend a posthole diameter of at least 3 times the width of the foundation post, or a minimum diameter of 12 inches, whichever is larger. We recommend placing at least 6 inches of concrete between the base of the hole and bottom of post. After the posts are set and adjusted for plumbness, the annulus should be filled with concrete. If significant wind loading is anticipated on a particular fence or gate due to its height or the installation of windscreens or netting, we recommend that AESI review the loading conditions and foundation post detail to confirm or adjust the posthole diameter and/or embedment depth. 13.0 FLOOR SUPPORT Where ground improvement is utilized for building support, we recommend that slab-on-grade floors be constructed over an array of vibratory stone columns or RAPs to mitigate post-liquefaction differential settlement. Where deep foundations are utilized for building support, we recommend that the lower-level floors be designed as structural floors using pile-supported grade beams. In order to control moisture vapor transfer through the slab, the slabs-on-grade should be cast atop a minimum of 4 inches of washed pea gravel or clean, washed crushed rock to act as a capillary break. It should also be protected from dampness by an impervious, 15-mil (minimum Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 36 thickness) plastic sheeting placed atop the capillary break specifically designed for use as a moisture barrier. 14.0 CAST-IN-PLACE RETAINING WALLS AND BELOW-GRADE WALLS We anticipate that most of the structures will be at or near existing grades with minimal site grading involved to establish final grades across the site. Our design and construction recommendations for cast-in-place retaining walls under 4 feet in height are presented below. If the project should require retaining walls greater than 4 feet in height, we are available to provide additional design parameters upon request. All backfill placed behind site walls and foundation walls should be placed in accordance with the recommendations contained in the “Structural Fill” section of this report. Horizontally backfilled walls, which are free to yield laterally at least 0.1 percent of their height, may be designed to resist lateral earth pressure represented by an equivalent fluid pressure equal to 35 pcf. Fully restrained, horizontally backfilled, rigid walls that cannot yield should be designed for an equivalent fluid pressure of 55 pcf. Walls with sloping backfill up to a maximum gradient of 2H:1V should be designed using an equivalent fluid pressure of 55 pcf for yielding conditions or 75 pcf for fully restrained conditions. If vehicle parking areas are adjacent to walls, we recommend a vertical surcharge equal to 250 psf be added to the wall height in determining the lateral design forces. In hardscape areas with pedestrian traffic, we recommend a live load vertical surcharge equal to 100 psf. The lateral pressure resulting from each vertical surcharge can be calculated by multiplying the surcharge load by 0.4 and applying the load as a rectangular distribution along the height of the wall. A qualified structural engineer should check the stability of site retaining walls with respect to sliding and overturning using the lateral earth pressures presented above. 15.0 DRAINAGE CONSIDERATIONS Traffic across the on-site soils when they are damp or wet will result in disturbance of the otherwise firm stratum. Therefore, during site work and construction, the contractor should provide surface drainage and subgrade protection, as necessary. Groundwater was encountered at depths between 9.5 and 14 feet at the time of our exploration and is likely shallower in the winter or following large storm events. Previous explorations at the site have indicated groundwater levels as shallow as 4.5 feet at the time of drilling in early March. Zones of perched groundwater may also be present within the fill at the contact with the finer-grained Black River alluvium, particularly after large storm events or near existing utility Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 37 backfill. Therefore, we recommend that contractors be prepared to encounter groundwater seepage within deeper excavations for utilities or other project elements. Where relatively shallow excavations on the order of 5 feet or less are required and take place in the drier months of the year, surface and groundwater seepage could be managed during construction with conventional ditches and sumps. Where deeper excavations greater than 5 feet are required and take place during the wet season, more complex dewatering systems may be required to maintain dry working conditions. All perimeter footings, slabs, and retaining walls should be provided with a drain at the footing or subgrade elevation. Drains should consist of rigid, perforated, PVC pipe surrounded by washed gravel. The level of the perforations in the pipe should be set at the bottom of the footing, and the perforations should be located on the lower portion of the pipe. The drains should be constructed with sufficient gradient to allow gravity discharge away from the structures. In addition, any retaining or subgrade walls should be lined with a minimum, 12-inch-thick, washed gravel blanket. Roof and surface runoff should not discharge into the footing drain system, but should be handled by a separate, rigid, tightline drain. In planning, exterior grades adjacent to walls should be sloped downward away from the structures at an inclination of at least 3 percent to achieve surface drainage. Runoff water from impervious surfaces should be collected by a storm drain system that discharges into the site stormwater system. 16.0 PAVEMENT RECOMMENDATIONS The pavement sections included in this report section are for driveway and parking areas onsite and are not applicable to right-of-way improvements. We are available to offer situation-specific recommendations for planned right-of-way improvements once project plans are more developed. Pavement areas should be prepared in accordance with the “Site Preparation” section of this report. If the existing fill subgrade can be compacted to 95 percent of ASTM D-1557 and is firm and unyielding during proof-rolling, no additional overexcavation is required. Soft or yielding areas should be overexcavated to provide a suitable subgrade and backfilled with structural fill. The upper 2 feet of pavement subgrade should be recompacted to 95 percent of ASTM D-1557. If required, structural fill may then be placed to achieve desired subbase grades. The near-surface existing fill soils across the site generally consisted of very loose to loose silty sand with scattered organics and appear to be marginal for pavement subgrade support in its current condition. We anticipate that subgrade preparation for new pavements will require remedial efforts, such as recompaction and overexcavation/replacement, and that these remedial efforts may be more extensive than typically needed for sites containing pavement Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 38 subgrades that are comprised of medium dense granular fill or native granular sediments. Therefore, our recommended pavement sections below include an overall thicker base course layer to account for the potentially marginal subgrades across the site. We anticipate the project will include light-duty pavements for passenger vehicles and heavy-duty pavements for buses, fire trucks, and garbage trucks. Our recommendations for asphalt pavement sections and concrete pavement sections are provided below. 16.1 Asphalt Pavement Sections In light-duty traffic areas, we recommend a pavement section consisting of 3 inches of hot-mix asphalt (HMA) underlain by 12 inches of ¼-inch crushed surfacing base course (Washington State Department of Transportation [WSDOT] 9-03.9(3) “CSBC” or approved equivalent) as the recommended minimum in areas of planned passenger car lanes and parking. In heavy-duty traffic areas, a minimum pavement section consisting of 4 inches of HMA underlain by 18 inches of CSBC is recommended. The CSBC must be compacted to 95 percent of the maximum density, as determined by ASTM D-1557. All paving materials should meet gradation criteria contained in the current WSDOT Standard Specifications. It should be noted that the performance of a pavement section is highly dependent on the subgrade conditions during construction. If pavement construction is planned for the dry summer months and the exposed subgrades are generally comprised of silty sand (as indicated by our exploration borings), are suitably compacted in place, and perform well during proof-rolling, the CSBC thickness could potentially be reduced to 6 inches for light-duty areas and 12 inches for heavy-duty areas. Where subgrade areas expose very silty subgrades that have lower support strength and/or construction takes place in wet weather conditions, the subgrade may require overexcavation/replacement with new structural fill or the placement of a stabilization fabric. Therefore, it is imperative that AESI be present during pavement subgrade preparation to assess if a reduced CSBC section can be achieved. Depending on construction staging and desired performance, a portion of the crushed rock base course layer may be substituted with ATB beneath the final asphalt surfacing. The substitution of ATB should be as follows: 4 inches of crushed rock can be substituted with 3 inches of ATB, and 6 inches of crushed rock may be substituted with 4 inches of ATB. ATB should be placed over a firm and unyielding subgrade as determined by proof-rolling and a 1½- to 2-inch thickness of crushed rock to act as a working surface. If ATB is used for construction access and staging areas, some rutting and disturbance of the ATB surface should be expected. The general contractor should remove affected areas and replace them with properly compacted ATB prior to final surfacing. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 39 16.2 Concrete Pavement Sections The following recommended sections for concrete pavements are preliminary and intended for planning purposes only. We are available to provide situation-specific designs if concrete pavements are included in the final design plans. In light-duty traffic areas, we anticipate a minimum pavement section consisting of 4 inches of concrete underlain by 6 inches of compacted CSBC. In heavy-duty traffic areas, we anticipate a minimum pavement section of 6 inches of concrete underlain by 12 inches of compacted CSBC. 17.0 INFILTRATION FEASIBILITY Stormwater infiltration feasibility depends upon the presence of a suitable native receptor soil of sufficient thickness, extent, permeability, and vertical separation from the groundwater table. Overall, infiltration appears very limited at the site based on our recent explorations, as further discussed below. Shallow-depth infiltration opportunities at the site are limited by the presence and thickness of surficial fills, low-permeability silt layers observed within the finer-grained Black River alluvial sediments directly underlying the fill, and relatively shallow groundwater conditions. Where higher-permeability Cedar River alluvial sediments are present directly below the existing fill, as encountered in EB-6W, the limiting factor for infiltration feasibility will be the separation between the base of the proposed infiltration facility and the seasonal high water table. At the time of drilling, groundwater was encountered at depths ranging from about 10 to 14 feet below the existing ground surface. AESI has monitored seasonal groundwater levels within the on-site wells (EB-1W, EB-3W, and EB-6W) starting from well development in April 2024 through June 25, 2025. A hydrograph illustrating approximate groundwater elevations and precipitation amounts over time is presented in Appendix D. During this monitoring period, groundwater elevations have ranged from about 20 to 22 feet in August/September 2024 (seasonal low) to about 23.5 to 26 feet in late March/early April 2025 (seasonal high). It should be noted that historical explorations at the site have indicated groundwater levels as shallow as 4.5 feet at the time of drilling in early March (see Table 2 in the “Hydrology” section of this report). 17.1 Infiltration Feasibility – Main School Campus We understand that no infiltration facilities are planned at this time. As discussed in the “Critical Aquifer Recharge Areas” section of this report, the approximate eastern half of the school campus and proposed improvements are located within a Zone 1 WHPA and the approximate western half of the school campus and proposed improvements are located within a Zone 2 WHPA. Per the City’s comprehensive water system plan, no infiltration is allowed within Zone 1 Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 40 WHPAs. Therefore, only the western track and field and parking lot area located within the Zone 2 WHPA could potentially utilize infiltration for this project; however, our exploration data in this area indicates that the western portion of the campus is primarily underlain by a surficial layer of existing fill overlying silty alluvial sediments accompanied by a shallow water table (approximately 7 to 10 feet below existing grade at the time of exploration). Therefore, infiltration opportunities in the Zone 2 area appear to be limited to shallow low-capacity infiltration BMPS such as permeable pavements or permeable roof drain leaders for small outbuildings. 17.2 Infiltration Feasibility – Northern Campus Expansion within Residential Block The campus expansion will include new athletic fields to the north within the existing 7-acre residential block that is bounded by South Tobin Street to the south, Shattuck Avenue South to the west, Airport Way to the north, and Logan Avenue South to the east. The eastern two-thirds of the residential block is located within a Zone 1 WHPA (no infiltration) while the western one-third is located within a Zone 2 WHPA. Based on our recent site observations made in July 2025 during house demolition and backfilling of basement structures in this area (Lots 1, 2, and 3), the subsurface soil conditions within the northern residential block appear similar to the subsurface conditions encountered within our borings across the main school campus. The near-surface soils observed during basement demolition generally consisted of silty sand. Additionally, the geothermal test loop borings GTL-1 and GTL-3 were located on the vacant parcel within the residential block and encountered fill soils (silty sand and sandy silt) to a depth of about 5 feet, underlain by Holocene alluvium that generally consisted of silty sand. Given the relatively flat topography across the site, we anticipate that groundwater levels below the residential block would be similar to groundwater levels encountered in EB-1W. Therefore, it appears that infiltration opportunities in the Zone 2 area would be limited to shallow low-capacity infiltration BMPs such as permeable pavements or permeable roof drain leaders for small outbuildings. 18.0 PROJECT DESIGN AND CONSTRUCTION MONITORING We recommend that AESI be allowed to review this report and update it as needed once the campus replacement plans are finalized. In this way, we can confirm that our earthwork and foundation recommendations have been properly interpreted and implemented in the design. We also recommend that AESI perform a geotechnical plan review of all earthwork- and foundation-related specifications prior to completion of the final design. We are available to provide geotechnical observation and testing services during construction. The integrity of the earthwork and foundations depends on proper site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. Subsurface Exploration, Geologic Hazard, Renton High School Replacement and Geotechnical Engineering Report Renton, Washington Design Recommendations September 3, 2025 ASSOCIATED EARTH SCIENCES, INC. BCY/ld – 20210249E002-007 Page 41 We have enjoyed working with you on this study and are confident these recommendations will aid in the successful completion of your project. If you should have any questions or require further assistance, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington ______________________________ Brendan C. Young, L.G. Senior Staff Geologist ______________________________ Matthew A. Miller, P.E. G. Bradford Drew, P.E. Principal Engineer Associate Engineer Attachments: Figure 1: Vicinity Map Figure 2: Existing Site and Exploration Plan Figure 3: Proposed Site and Exploration Plan Appendix A: Boring Logs Appendix B: CPT Logs Appendix C: Historical Exploration Logs (AESI, 1999, 2009, 2024) Appendix D: Hydrograph Appendix E: Laboratory Test Results Appendix F: Liquefaction Analysis Results Appendix G: Shear Wave Velocity Survey (WGS, 2020) Appendix H: Wellhead Protection Zone Map G: \ G I S _ P r o j e c t s \ a a Y 2 0 2 1 \ 2 1 0 2 4 9 R e n t o n H S \ _ a p r x \ 2 0 2 1 0 2 4 9 E 0 0 2 F 1 VM _ R e n t o n H S . a p r x | 2 0 2 1 0 2 4 9 E 0 0 2 F 1 V M _ R e n t o n H S | 2 0 2 4 - 0 4 - 0 4 | k b e h m COUNTY LOCALE LOCATION PROJECT NO.DATE FIGURE 13/2520210249E002 RENTON HIGH SCHOOL RENTON, WASHINGTON VICINITY MAP ESRI, USGS, NATIONAL GEOGRAPHIC,DELORME, NATURALVUE, I-CUBED, GEBCO:ARCGIS ONLINE BASEMAP. WADOT STATEROUTES 24K (12/20). KING CO: PARCELS(4/23), ROADS (5/23). NOTE: LOCATION AND DISTANCES SHOWNARE APPROXIMATE. BLACK AND WHITEREPRODUCTION OF THIS COLOR ORIGINALMAY REDUCE ITS EFFECTIVENESS AND LEADTO INCORRECT INTERPRETATION. King County S TOBIN ST SR 900 LO G A N A V E S 405 515 900 167 169 Lake Washington K I N G COUNTY KI N G CO U N T Y RENTON SE A T T L E 0 2,000 FEET m SITE BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAYREDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION.LOCATION AND DISTANCES SHOWN ARE APPROXIMATE. G: \ G I S _ P r o j e c t s \ a a Y 2 0 2 1 \ 2 1 0 2 4 9 R e n t o n H S \ _ a p r x \ E 0 0 2 _ 2 5 0 3 \ 2 0 2 1 0 2 49 E 0 0 2 F 2 E S _ R e n t o n H S _ 2 5 0 3 . a p r x | 2 0 2 1 0 2 4 9 E 0 0 2 F 2 E S _ R H S _ 2 5 0 3 | 2 0 2 5 - 0 4 - 2 1 | m t r o p PROJECT NO.DATE FIGURE ± 24/2520210249E002 RENTON HIGH SCHOOL RENTON, WASHINGTON EXISTING SITE AND EXPLORATIONS DATA SOURCES / REFERENCES: WADNR WGS: WA LIDAR PORTAL, KING CO. 2021, USGS 3DEP GRID CELL SIZE 1.5', FLOWN 4/2021 CONTOURS DERIVED FROM LIDAR KING CO: STREETS, PARCELS, 4/23 AERIAL PICTOMETRY INT. 2021 0 150 FEET ^ dŽďŝŶ ^ƚ ^w ϵϬϬ > Ă Ŭ Ğ ǀ Ğ ^ > Ž Ő Ă Ŷ ǀ Ğ ^ ^w ϵϬϬ ŝƌƉŽƌƚ tĂLJ ^dŝůůŝĐƵŵ ^ƚ (3 (3 (3 (3 (% (% (% (% (% (% (% (% (% (% (% (% (% (% (% (% (% (% (%: (%(%: (% (% (%: &37 &37 &37 (3 (3 *7/ (% (% (% (% (% (% *7/ *7/ 3 34 3 30 3 3 34 32 2 3 34 3 2 2 4 4 3 2 30 32 2 3 3 3 3 3 34 34 34 32 32 34 34 3 4 32 32 RentonHighSchool ERI EW LLQH SITE EXPLORATION TYPE - YEAR EXPLORATION BORING MONITORING WELL EXPLORATION PIT CONE PENETROMETER GEOTHERMAL TEST LOOP SEISMIC ARRAY (WADNR WGS OFR 2019-01) ERI E-W LINE PARCEL CONTOUR 10 FT CONTOUR 2 FT BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAYREDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION.LOCATION AND DISTANCES SHOWN ARE APPROXIMATE. G: \ G I S _ P r o j e c t s \ a a Y 2 0 2 1 \ 2 1 0 2 4 9 R e n t o n H S \ _ a p r x \ E 0 0 2 _ 2 5 0 3 \ 2 0 2 1 0 2 49 E 0 0 2 F 3 S P _ R e n t o n H S _ 2 5 0 3 . a p r x | 2 0 2 1 0 2 4 9 E 0 0 2 F 3 S P _ R H S _ 2 5 0 3 | 2 0 2 5 - 0 8 - 1 1 | m t r o p PROJECT NO.DATE FIGURE ± 38/2520210249E002 RENTON HIGH SCHOOL RENTON, WASHINGTON PROPOSED SITE PLAN AND EXPLORATIONS DATA SOURCES / REFERENCES: AHBL, RENTON HIGH SCHOOL REPLACEMENT, PROJECT PLAN, SHEET C1.0, 6/6/25 0 150 FEET EP-1-99 EP-2-99 EP-3-99 EP-4-99 EB-1-99 EB-2-99 EB-3-99 EB-4-99 EB-1-09EB-2-09EB-3-09 EB-4-09 EB-5-09 EB-6-09 EB-7-09EB-8-09 EB-9-09 EB-10-09 EB-11-09 EB-12-09 EB-13-09 EB-14-09 EB-1W-24 EB-2-24 EB-3W-24 EB-4-24 EB-5-24 EB-6W-24 CPT-01-24 CPT-02-24 CPT-03-24 EP-1-24 EP-2-24 GTL-1-24 EB-1-03 EB-2-03EB-3-03 EB-4-03 EB-5-03EB-6-03 GTL-2-25 GTL-3-25 (5,(:/LQH SITE EXPLORATION TYPE - YEAR EXPLORATION BORING MONITORING WELL EXPLORATION PIT CONE PENETROMETER GEOTHERMAL TEST LOOP SEISMIC ARRAY (WADNR WGS OFR 2019-01) ERI E-W LINE APPENDIX A Boring Logs Classifications of soils in this report are based on visual field and/or laboratory observations, which include density/consistency, moisture condition, grain size, and plasticity estimates and should not be construed to imply field or laboratory testing unless presented herein. Visual-manual and/or laboratory classification methods of ASTM D-2487 and D-2488 were used as an identification guide for the Unified Soil Classification System. OH PT CH OL MH CL ML SM SC GW SP GC SW GM GP Well-graded gravel and gravel with sand, little to no fines Poorly-graded gravel and gravel with sand, little to no fines Clayey gravel and clayey gravel with sand Silty gravel and silty gravel with sand Well-graded sand and sand with gravel, little to no fines Poorly-graded sand and sand with gravel, little to no fines Clayey sand and clayey sand with gravel Organic clay or silt of low plasticity Organic clay or silt of medium to high plasticity Peat, muck and other highly organic soils Silty sand and silty sand with gravel Silt, sandy silt, gravelly silt, silt with sand or gravel Clay of low to medium plasticity; silty, sandy, or gravelly clay, lean clay Elastic silt, clayey silt, silt with micaceous or diatomaceous fine sand or silt Clay of high plasticity, sandy or gravelly clay, fat clay with sand or gravel (1 ) Hi g h l y Or g a n i c So i l s Fi n e - G r a i n e d S o i l s - 5 0 % o r M o r e P a s s e s N o . 2 0 0 S i e v e (1 ) Co a r s e - G r a i n e d S o i l s - M o r e t h a n 5 0 % R e t a i n e d o n N o . 2 0 0 S i e v e Gr a v e l s - M o r e t h a n 5 0 % o f C o a r s e F r a c t i o n Re t a i n e d o n N o . 4 S i e v e 12 % F i n e s 5% F i n e s Sa n d s - 5 0 % o r M o r e o f C o a r s e F r a c t i o n Pa s s e s N o . 4 S i e v e Si l t s a n d C l a y s Li q u i d L i m i t L e s s t h a n 5 0 Si l t s a n d C l a y s Li q u i d L i m i t 5 0 o r M o r e (1 ) (1 ) 12 % F i n e s 5% F i n e s (2 ) (2 ) (2 ) (2 ) Terms Describing Relative Density and Consistency Estimated Percentage Moisture Content Percentage by Weight <5 5 to <12 12 to <30 30 to <50 Component Definitions Component Trace Some Modifier (silty, sandy, gravelly) Very modifier (silty, sandy, gravelly) Size Range and Sieve Number Larger than 12" Descriptive Term Smaller than No. 200 (0.075 mm) 3" to 12" Coarse- Grained Soils Fine- Grained Soils Density Very Loose Loose Medium Dense Dense Very Dense SPT blows/foot 0 to 4 4 to 10 10 to 30 30 to 50 >50 (3) 0 to 2 2 to 4 4 to 8 8 to 15 15 to 30 >30 Consistency Very Soft Soft Medium Stiff Stiff Very Stiff Hard SPT blows/foot(3) Test Symbols No. 4 (4.75 mm) to No. 200 (0.075 mm) Boulders Silt and Clay Gravel Coarse Gravel Fine Gravel Cobbles Sand Coarse Sand Medium Sand Fine Sand Dry - Absence of moisture, dusty, dry to the touch Slightly Moist - Perceptible moisture Moist - Damp but no visible water Very Moist - Water visible but not free draining Wet - Visible free water, usually from below water table G = Grain Size M = Moisture Content A = Atterberg Limits C = Chemical DD = Dry Density K = Permeability No. 4 (4.75 mm) to No. 10 (2.00 mm) No. 10 (2.00 mm) to No. 40 (0.425 mm) No. 40 (0.425 mm) to No. 200 (0.075 mm) 3" to No. 4 (4.75 mm) 3" to 3/4" 3/4" to No. 4 (4.75 mm) Symbols Sampler Type and Description Blows/6" or portion of 6"15 10 20 California Sampler Ring Sampler Continuous Sampling Grab Sample Portion not recovered Split-Spoon Sampler (SPT) Cement grout surface seal Bentonite seal Filter pack with blank casing section Screened casing or Hydrotip with filter pack End cap ATD At time of drilling Static water level (date) (1)Percentage by dry weight(2)Combined USCS symbols used for fines between 5% and 12%(3)(SPT) Standard Penetration Test (ASTM D-1586)(4)In General Accordance with Standard Practice for Description and Identification of Soils (ASTM D-2488) Groundwater depth i n c o r p o r a t e d e a r t h s c i e n c e s a s s o c i a t e d EXPLORATION LOG KEY FIGURE:A1Bl o c k s \ d w g \ l o g _ k e y 2 0 2 2 . d w g L A Y O U T : L a y o u t 5 - 2 0 2 2 L o g d r a f t 0 5 10 15 20 25 30 35 1 2 3 4 5 6 7 8 9 10 Asphalt - 3 inches / No Base Course FillMoist, dark brown to black transitioning to brown, gravelly, SAND, some silt becoming silty, fine SAND, some gravel with depth; rare organics (rootlets (SP- SM).Moist, brown with oxidation staining to orange, fine SAND, trace silt (SP). Black River AlluviumVery moist, gray with orange oxidation staining, fine sandy, SILT, trace to some gravel (ML).Very moist, gray, sandy, SILT, trace gravel; scattered organics (fine organics and rootlets); occasional interbed of fine sand; organic odor (ML).Very moist, gray, SILT; occasional brown silt, some fine sand; interbeds of fine to medium sand, some silt (ML).Wet, gray, silty, fine to medium SAND; occasional interbed of fine sandy, silt, trace organics (SM).Driller adding water and drilling fluid. Wet, gray, fine sandy, SILT; occasional interbeds of fine sand; rare fine organics (ML). As above; occasional interbeds of fine to medium sand (ML). Cedar River AlluviumDriller notes increase in gravel. Wet, brown, fine to coarse SAND (coarsening with depth); trace silt; some gravel at tip of spoon (SP). Wet, brownish gray, fine to medium SAND; becoming medium to coarse sand, some gravel; rare interbed of gray, silt (SP). Wet, brownish gray, fine to medium SAND, some gravel; massive (SP-SM). 142614 111 111 111 222 111 224 244 677 67 40 2 2 2 4 2 6 8 14 15 Flush mount monumentConcrete 0 to 2 feet Bentonite chips 2 to 8 feet 2-inch I.D. sch. 40 PVC casing 0 to 10 feet Sand 8 to 22 feet 2-inch I.D. PVC well screen 0.010-inch slot width 10 to 20 feet End cap; threaded connection Slough 22 to 51.5 feet Associated Earth Sciences, Inc. Monitoring Well EB-1W Renton High School Replacement Renton, Washington Start Date: 4/9/2024 Logged By: BCY 20210249E002 Ending Date: 4/9/2024 Approved By: JHS Driller/Equipment:ADT/D-50 Hollow Stem Auger Total Depth (ft):51.5Hammer Weight/Drop:140#/30"Well Completion Depth (ft):20Hole Diameter (in):6 Well Tag No.:BPQ286Ground Surface Elevation (ft):»32 Top of Well Casing Elevation (ft):»31.7Water Level Elevation (ft):20.2 Datum:NAVD 88Groundwater Depth ATD (ft): 11.8 Groundwater Depth Post Drilling (ft) (Date): 9.5 ( 4/29/24 ) De p t h ( f t ) Sa m p l e T y p e Sa m p l e N o . Gr a p h i c Sy m b o l Description Wa t e r L e v e l B l o w s / 6 " Blows/Foot 1 0 2 0 3 0 4 0 5 0 + Well Construction 20 2 1 0 2 4 9 E 0 0 2 5/ 1 5 / 2 0 2 4 Sheet: 1 of 2 40 45 50 55 60 65 70 11 12 13 Driller notes layers of sand and layers of gravel; changing drill action. As above; gravel in bottom 3 inches of spoon; interbeds of brown, silty, fine sand (SP). As above; sandy (6 inches thick) at tip of spoon; broken gravel; blow counts may be overstated. Wet, brownish gray, fine to medium SAND, trace gravel; oxidation staining around gravel; blow counts may be overstated (SP). Groundwater encountered at 11.8 feet ATD. Groundwater encountered at 9.5 feet on 4/29/24. 8 131116 101527 141625 27 42 41 Associated Earth Sciences, Inc. Monitoring Well EB-1W Renton High School Replacement Renton, Washington Start Date: 4/9/2024 Logged By: BCY 20210249E002 Ending Date: 4/9/2024 Approved By: JHS Driller/Equipment:ADT/D-50 Hollow Stem Auger Total Depth (ft):51.5Hammer Weight/Drop:140#/30"Well Completion Depth (ft):20Hole Diameter (in):6 Well Tag No.:BPQ286Ground Surface Elevation (ft):»32 Top of Well Casing Elevation (ft):»31.7Water Level Elevation (ft):20.2 Datum:NAVD 88Groundwater Depth ATD (ft): 11.8 Groundwater Depth Post Drilling (ft) (Date): 9.5 ( 4/29/24 ) De p t h ( f t ) Sa m p l e T y p e Sa m p l e N o . Gr a p h i c Sy m b o l Description Wa t e r L e v e l B l o w s / 6 " Blows/Foot 1 0 2 0 3 0 4 0 5 0 + Well Construction 20 2 1 0 2 4 9 E 0 0 2 5/ 1 5 / 2 0 2 4 Sheet: 2 of 2 0 5 10 15 20 25 30 35 1 2 3 4 5 6 7 8 9 10 Sod / Topsoil - 3 inches FillMoist, dark brown, silty, fine to medium SAND, some gravel; abundant organics (fine black organics and rootlets) (SM).Slightly moist, brown with some dark brown and orangish brown, silty, fine to medium SAND, some gravel; scattered organics (charcoal and rootlets) (SM). Black River AlluviumSlightly moist, brownish gray with some orange oxidation staining, fine SAND, some silt (SP-SM). Moist to very moist, gray to dark brown, SILT to organic SILT; abundant fine organics with strong odor; massive (ML/OL). As above; occasional interbeds (approximately 1 inch thick) of fine sand; fewer organics (ML). As above; becomes wet with rare wood debris. Cedar River Alluvium Driller notes gravel. Driller adding water. Wet, gray, fine SAND; becomes medium to coarse sand with depth, trace silt; transitioning to gravel, some coarse sand, trace silt at bottom of sample (SP- GP). Wet, brown and gray, sandy, GRAVEL, trace silt; broken gravel; stratified; blow counts overstated (GW). Wet, grayish brown, silty, GRAVEL, some sand; occasional interbed of gray, silty, fine sand (GM). Wet, gray, silty, fine SAND, some gravel (SM). 598 143 322 232 212 213 141415 121520 743 9913 17 7 4 5 3 4 29 35 7 22 Associated Earth Sciences, Inc. Exploration Boring EB-2 Renton High School Replacement 1 Renton, Washington Start Date: 4/10/2024 Logged By: BCY 20210249E002 Ending Date: 4/10/2024 Approved By: JHS Driller/Equipment: ADT/D-50 Hollow Stem Auger Total Depth (ft):51.5Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»34Hole Diameter (in):6 Datum:NAVD 88Groundwater Depth ATD (ft):13.3 Groundwater Depth Post Drilling (ft) (Date): () De p t h ( f t ) Sa m p l e T y p e Sa m p l e % R e c o v e r y Gr a p h i c Sy m b o l Description Wa t e r L e v e l Bl o w s / 6 " Blows/Foot 1 0 2 0 3 0 4 0 5 0 + Ot h e r T e s t s 20 2 1 0 2 4 9 E 0 0 2 5/ 1 5 / 2 0 2 4 Sheet: 1 of 2 40 45 50 55 60 65 70 75 11 12 13 Wet, brown, fine to medium SAND, some gravel, some silt; interbedded with gray, silty, fine SAND, trace organics (SP-SM). Wet, brown, sandy, GRAVEL, some silt; broken gravel in sampler; blow counts may be overstated (GW-GM). Wet, brown, silty, GRAVEL, some fine to medium sand (GM). Groundwater encountered at 13.3 feet ATD. Practical auger refusal due to large gravels. 121516 222528 261816 31 53 34 Associated Earth Sciences, Inc. Exploration Boring EB-2 Renton High School Replacement 2 Renton, Washington Start Date: 4/10/2024 Logged By: BCY 20210249E002 Ending Date: 4/10/2024 Approved By: JHS Driller/Equipment: ADT/D-50 Hollow Stem Auger Total Depth (ft):51.5Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»34Hole Diameter (in):6 Datum:NAVD 88Groundwater Depth ATD (ft):13.3 Groundwater Depth Post Drilling (ft) (Date): () De p t h ( f t ) Sa m p l e T y p e Sa m p l e % R e c o v e r y Gr a p h i c Sy m b o l Description Wa t e r L e v e l Bl o w s / 6 " Blows/Foot 1 0 2 0 3 0 4 0 5 0 + Ot h e r T e s t s 20 2 1 0 2 4 9 E 0 0 2 5/ 1 5 / 2 0 2 4 Sheet: 2 of 2 0 5 10 15 20 25 30 35 1 2 3 4 5 6 7 8 9 10 Sod / Topsoil - 3 inches FillSlightly moist, brown, silty, fine SAND; scattered to abundant organics (charcoal and rootlets); silt content decreases with depth (SM).Slightly moist, brown, silty, SAND, some gravel; scattered to abundant organics (charcoal/rootlets) (SM). Black River AlluviumVery moist, brown and gray with orange oxidation staining, SILT, some fine sand; occasional interbed of fine sand, some fine organics (ML).Moist, brown to orange, very silty, fine SAND, trace gravel; occasional interbed of brownish gray, silt; pockets of heavily organic, dark brown, silty, sand (SM).Wet, brown to reddish brown, fine SAND, and silty, fine SAND; becomes gravelly, sand, some silt (at 11 feet); faintly stratified (SM). Wet, brown becoming gray, fine SAND, some silt; large piece (3 inches) of wood debris at top of spoon (SP-SM). Wet, gray, silty, fine SAND; interbeds (<2.5 inches thick) of gray, fine sand; some gravel (SM). Wood debris present at 21 feet. Wet, gray, silty, fine SAND, trace gravel; wood debris, rare rootlets; broken gravel at tip of spoon; abundant fine organics; blow counts may be overstated (SM). Cedar River Alluvium Wet, brown, sandy, GRAVEL, trace silt; blow counts may be overstated (GW). Wet, brown, GRAVEL, some medium sand, trace silt (GW). 224 322 111 543 2610 213 81016 6815 81321 148 6 4 2 7 16 4 26 23 34 17 Flush mount monumentConcrete 0 to 2 feet Bentonite chips 2 to 10 feet 2-inch I.D. sch. 40 PVC casing 0 to 13.4 feet Sand 10 to 26 feet 2-inch I.D. sch. 40 PVC well screen 0.010-inch slot width 13.4 to 23.4 feet Endcap Slough 26 to 51.5 feet Associated Earth Sciences, Inc. Monitoring Well EB-3W Renton High School Replacement Renton, Washington Start Date: 4/10/2024 Logged By: BCY 20210249E002 Ending Date: 4/10/2024 Approved By: JHS Driller/Equipment:ADT/D-50 Hollow Stem Auger Total Depth (ft):51.5Hammer Weight/Drop:140#/30"Well Completion Depth (ft):23.4Hole Diameter (in):6 Well Tag No.:BPQ287Ground Surface Elevation (ft):»34 Top of Well Casing Elevation (ft):»33.6Water Level Elevation (ft):20.4 Datum:NAVD 88Groundwater Depth ATD (ft): 13.6 Groundwater Depth Post Drilling (ft) (Date): 12.1 ( 4/29/24 ) De p t h ( f t ) Sa m p l e T y p e Sa m p l e N o . Gr a p h i c Sy m b o l Description Wa t e r L e v e l B l o w s / 6 " Blows/Foot 1 0 2 0 3 0 4 0 5 0 + Well Construction 20 2 1 0 2 4 9 E 0 0 2 5/ 1 5 / 2 0 2 4 Sheet: 1 of 2 40 45 50 55 60 65 70 11 12 13 Wet, brown, very sandy, GRAVEL, trace silt; blow counts may be overstated (GW). Wet, brown to brownish gray, fine SAND, trace silt; layered with GRAVEL, some fine to medium sand, trace silt; broken gravel in split spoon (SP). Wet, brownish gray with occasional deep red oxidation staining, fine to medium SAND, some gravel, trace to some silt; blow counts may be overstated (SP-SM). Groundwater encountered at 13.6 feet ATD. Groundwater encountered at 12.1 feet on 4/29/ 24. Practical auger refusal due to large gravel. 9 262318 8911 341826 41 20 44 Associated Earth Sciences, Inc. Monitoring Well EB-3W Renton High School Replacement Renton, Washington Start Date: 4/10/2024 Logged By: BCY 20210249E002 Ending Date: 4/10/2024 Approved By: JHS Driller/Equipment:ADT/D-50 Hollow Stem Auger Total Depth (ft):51.5Hammer Weight/Drop:140#/30"Well Completion Depth (ft):23.4Hole Diameter (in):6 Well Tag No.:BPQ287Ground Surface Elevation (ft):»34 Top of Well Casing Elevation (ft):»33.6Water Level Elevation (ft):20.4 Datum:NAVD 88Groundwater Depth ATD (ft): 13.6 Groundwater Depth Post Drilling (ft) (Date): 12.1 ( 4/29/24 ) De p t h ( f t ) Sa m p l e T y p e Sa m p l e N o . Gr a p h i c Sy m b o l Description Wa t e r L e v e l B l o w s / 6 " Blows/Foot 1 0 2 0 3 0 4 0 5 0 + Well Construction 20 2 1 0 2 4 9 E 0 0 2 5/ 1 5 / 2 0 2 4 Sheet: 2 of 2 0 5 10 15 20 25 30 35 1 2 3 4 5 6 7 8 9 10 Sod / Topsoil - 3 inches FillSlightly moist to moist, brown to dark brown, very gravelly, silty, SAND; scattered organic rootlets); bottom 3 inches becomes brown, fine to medium SAND, some gravel, trace silt (SM).Slightly moist, dark brown transitioning to brown mixed with tan with occasional faint orange oxidation staining, silty, fine to medium SAND, some gravel; scattered organics (rootlets); disturbed texture (SM). Black River AlluviumMoist grayish brown with abundant oxidation staining to orange, sandy, SILT ranging to very silty, fine SAND, rare gravel; scattered organics (fine black organics and rootlets); organics appear in some horizontal interbeds (ML/ SM).Moist, grayish brown, sandy, SILT ranging to SILT; occasional layer (<1 inch thick) of heavily oxidized, sand; scattered organics (charcoal and rootlets) (ML).Moist, gray to brown with heavy oxidation staining to orange, sandy, SILT, some gravel; occasional interbed (<1 inch thick) of fine sand (ML). Wet, gray and brown, fine SAND, some silt; occasional interbed of silty, fine to medium sand, fine gravel at tip of spoon (SP-SM). Driller notes increasing gravel content. Wet, gray, fine to coarse SAND, some gravel, trace silt; sample coarsens with depth; gravel in tip of sampler; blow counts may be overstated (SP). Cedar River Alluvium Wet, brown, sandy, GRAVEL, trace silt; gravel filled diameter of sampler; blow counts may be overstated (GW). Wet, brown with heavy oxidation staining, very sandy, GRAVEL, some silt; massive (GP-GM). As above; broken gravel in spoon; blow counts may be overstated. 51011 111 111 212 213 025 101820 232318 5910 131718 21 2 2 3 4 7 38 41 19 35 Associated Earth Sciences, Inc. Exploration Boring EB-4 Renton High School Replacement 1 Renton, Washington Start Date: 4/9/2024 Logged By: BCY 20210249E002 Ending Date: 4/9/2024 Approved By: JHS Driller/Equipment: ADT/D-50 Hollow Stem Auger Total Depth (ft):45.5Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»34Hole Diameter (in):6 Datum:NAVD 88Groundwater Depth ATD (ft):14.1 Groundwater Depth Post Drilling (ft) (Date): () De p t h ( f t ) Sa m p l e T y p e Sa m p l e % R e c o v e r y Gr a p h i c Sy m b o l Description Wa t e r L e v e l Bl o w s / 6 " Blows/Foot 1 0 2 0 3 0 4 0 5 0 + Ot h e r T e s t s 20 2 1 0 2 4 9 E 0 0 2 5/ 1 5 / 2 0 2 4 Sheet: 1 of 2 40 45 50 55 60 65 70 75 11 12 As above; broken gravel in spoon; blow counts may be overstated. Wet, brownish gray, gravelly, medium to coarse SAND, trace silt (SP). Groundwater encountered at 14.1 feet ATD. Practical auger refusal due to large gravel. 202221 231617 43 33 Associated Earth Sciences, Inc. Exploration Boring EB-4 Renton High School Replacement 2 Renton, Washington Start Date: 4/9/2024 Logged By: BCY 20210249E002 Ending Date: 4/9/2024 Approved By: JHS Driller/Equipment: ADT/D-50 Hollow Stem Auger Total Depth (ft):45.5Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»34Hole Diameter (in):6 Datum:NAVD 88Groundwater Depth ATD (ft):14.1 Groundwater Depth Post Drilling (ft) (Date): () De p t h ( f t ) Sa m p l e T y p e Sa m p l e % R e c o v e r y Gr a p h i c Sy m b o l Description Wa t e r L e v e l Bl o w s / 6 " Blows/Foot 1 0 2 0 3 0 4 0 5 0 + Ot h e r T e s t s 20 2 1 0 2 4 9 E 0 0 2 5/ 1 5 / 2 0 2 4 Sheet: 2 of 2 0 5 10 15 20 25 30 35 1 2 3 4 5 6 7 8 9 10 Asphalt - 3 inches / Base Course »4 to 6 inches FillSlightly moist, brown mixed with dark gray, silty, fine to medium SAND, some gravel; disturbed texture; fine organics (rootlets) (SM).Slightly moist, brown mixed with gray, silty, fine to coarse SAND, some gravel (SM). Black River AlluviumLower 3 inches: Moist, gray with occasional oxidation staining to orange, sandy, SILT (ML).Moist, brown and gray with faint oxidation staining, fine sandy, SILT; stratified; occasional interbed of brown, silty, fine sand (ML).Moist, orange brown, silty, fine SAND; transitioning to gray with minor oxidation staining, silty, fine sand at tip of spoon (SM).Wet, brown to orange brown, silty, fine SAND; occasional gray, silty interbed; faintly stratified (SM). Wet, gray with some brown, very sandy, GRAVEL, some silt; gravel the full diameter of sampler present; blow counts may be slightly overstated (GP- GM).Driller notes increase in gravel. Cedar River AlluviumDriller adding drilling fluid. Wet, gray, fine SAND, some silt with a layer of GRAVEL, some fine to coarse sand, trace silt at bottom of spoon (SP-SM). Wet, gray, gravelly, fine to medium SAND, trace silt; poor recovery; broken gravel in sampler; blow counts likely overstated (SP). Wet, gray, sandy, GRAVEL; poor recovery; pushing rock at tip of sampler (GW). Wet, gray to brownish gray, sandy, GRAVEL, trace silt; broken gravel in sampler; blow count overstated (GW). 797 1023 111 234 257 51014 81417 22023 201917 162131 16 5 2 7 12 24 31 43 36 52 Associated Earth Sciences, Inc. Exploration Boring EB-5 Renton High School Replacement 1 Renton, Washington Start Date: 4/11/2024 Logged By: BCY 20210249E002 Ending Date: 4/11/2024 Approved By: JHS Driller/Equipment: ADT/D-50 Hollow Stem Auger Total Depth (ft):51.5Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»34Hole Diameter (in):6 Datum:NAVD 88Groundwater Depth ATD (ft):10 Groundwater Depth Post Drilling (ft) (Date): () De p t h ( f t ) Sa m p l e T y p e Sa m p l e % R e c o v e r y Gr a p h i c Sy m b o l Description Wa t e r L e v e l Bl o w s / 6 " Blows/Foot 1 0 2 0 3 0 4 0 5 0 + Ot h e r T e s t s 20 2 1 0 2 4 9 E 0 0 2 5/ 1 5 / 2 0 2 4 Sheet: 1 of 2 40 45 50 55 60 65 70 75 11 12 13 As above. Wet, brownish gray, medium SAND, trace silt; poor recovery; driller notes pushing gravel at tip of sample; blow counts overstated (SP). Wet, oxidized brown, silty, fine SAND; stratified with gray, medium SAND, trace gravel, some silt (SM). Groundwater encountered at 10 feet ATD. Practical auger refusal due to large gravel. 182320 192526 10811 43 51 19 Associated Earth Sciences, Inc. Exploration Boring EB-5 Renton High School Replacement 2 Renton, Washington Start Date: 4/11/2024 Logged By: BCY 20210249E002 Ending Date: 4/11/2024 Approved By: JHS Driller/Equipment: ADT/D-50 Hollow Stem Auger Total Depth (ft):51.5Hammer Weight/Drop:140#/30"Ground Surface Elevation (ft):»34Hole Diameter (in):6 Datum:NAVD 88Groundwater Depth ATD (ft):10 Groundwater Depth Post Drilling (ft) (Date): () De p t h ( f t ) Sa m p l e T y p e Sa m p l e % R e c o v e r y Gr a p h i c Sy m b o l Description Wa t e r L e v e l Bl o w s / 6 " Blows/Foot 1 0 2 0 3 0 4 0 5 0 + Ot h e r T e s t s 20 2 1 0 2 4 9 E 0 0 2 5/ 1 5 / 2 0 2 4 Sheet: 2 of 2 0 5 10 15 20 25 30 35 1 2 3 4 5 6 7 8 9 10 Sod / Topsoil - 3 inches FillSlightly moist, dark brown, silty, fine SAND, trace to some gravel; abundant organics (rootlets) (SM).Slightly moist, gray, fine SAND; mixed with dark brown, silty, fine SAND; scattered organics (rootlets; broken gravel in spoon; blow counts may be overstated (SM).As above; slightly moist to moist, some gravel. Cedar River AlluviumSlightly moist, brown to grayish brown, sandy, GRAVEL, trace to some silt; rare organics (rootlets); gravel filled diameter of sampler; blow counts may be overstated (GP-GM).Slightly moist, brownish gray, sandy, GRAVEL, trace to some silt; broken gravel in spoon; blow counts may be overstated (GP-GM). Wet, gray to brownish gray, sandy to very sandy, GRAVEL, trace to some silt; rare organics (wood debris) (GP-GM). Wet, brownish gray, sandy, GRAVEL, trace silt; rare interbed (»2 inches thick) of fine sand, some silt; broken gravel in split spoon; blow counts may be overstated (GW). Wet, brown, GRAVEL, some fine to medium sand, trace silt; poor recovery; broken gravel in split spoon; blow counts may be overstated (GW). Wet, brown, fine to medium SAND, some silt, some gravel; broken gravel at tip of sample; blow counts may be overstated (SP-SM). Wet, brown, fine to medium SAND, trace gravel; sampler was over filled and may contain heaved 156 568 61110 161819 182618 11811 101433 132425 132321 50/4" 11 14 21 37 44 19 47 49 44 50/4" Concrete 0 to 2 feet Bentonite chips 2 to 11 feet 2-inch I.D. PVC casing 0 to 14.5 feet Sand 11 to 26 feet 2-inch I.D. PVC well screen 0.010-inch slot width 14.4 to 24.4 feet Well pointed end cap with threads Slough 26 to 51.5 feet Associated Earth Sciences, Inc. Monitoring Well EB-6W Renton High School Replacement Renton, Washington Start Date: 4/11/2024 Logged By: BCY 20210249E002 Ending Date: 4/11/2024 Approved By: JHS Driller/Equipment:ADT/D-50 Hollow Stem Auger Total Depth (ft):51.5Hammer Weight/Drop:140#/30"Well Completion Depth (ft):26.5Hole Diameter (in):6 Well Tag No.:BPQ288Ground Surface Elevation (ft):»36 Top of Well Casing Elevation (ft):»35.8Water Level Elevation (ft):21.7 Datum:NAVD 88Groundwater Depth ATD (ft): 14.3 Groundwater Depth Post Drilling (ft) (Date): 14.1 ( 4/26/24 ) De p t h ( f t ) Sa m p l e T y p e Sa m p l e N o . Gr a p h i c Sy m b o l Description Wa t e r L e v e l B l o w s / 6 " Blows/Foot 1 0 2 0 3 0 4 0 5 0 + Well Construction 20 2 1 0 2 4 9 E 0 0 2 5/ 1 5 / 2 0 2 4 Sheet: 1 of 2 40 45 50 55 60 65 70 11 12 13 material; blow counts overstated (SP). Wet, fine to medium SAND, trace to some silt; becomes gravelly at bottom 3 inches (SP-SM). Wet, grayish brown, fine SAND, trace silt; occasional interbed (<3 inches thick) of brown, medium to coarse sandy, gravel (SP). Driller notes transition into gravel with heavy drill chatter. No recovery; attempted additional sample with Cal- Mod sampler, no recovery. Groundwater encountered at 14.3 feet ATD. Groundwater encountered at 14.1 feet on 4/26/ 24. Practical auger refusal due to large gravel. 101520 141610 101210 35 26 22 Associated Earth Sciences, Inc. Monitoring Well EB-6W Renton High School Replacement Renton, Washington Start Date: 4/11/2024 Logged By: BCY 20210249E002 Ending Date: 4/11/2024 Approved By: JHS Driller/Equipment:ADT/D-50 Hollow Stem Auger Total Depth (ft):51.5Hammer Weight/Drop:140#/30"Well Completion Depth (ft):26.5Hole Diameter (in):6 Well Tag No.:BPQ288Ground Surface Elevation (ft):»36 Top of Well Casing Elevation (ft):»35.8Water Level Elevation (ft):21.7 Datum:NAVD 88Groundwater Depth ATD (ft): 14.3 Groundwater Depth Post Drilling (ft) (Date): 14.1 ( 4/26/24 ) De p t h ( f t ) Sa m p l e T y p e Sa m p l e N o . Gr a p h i c Sy m b o l Description Wa t e r L e v e l B l o w s / 6 " Blows/Foot 1 0 2 0 3 0 4 0 5 0 + Well Construction 20 2 1 0 2 4 9 E 0 0 2 5/ 1 5 / 2 0 2 4 Sheet: 2 of 2 APPENDIX B CPT Logs CPT-01 CPT Contractor: In SItu Engineering CUSTOMER: AES LOCATION: Renton JOB NUMBER: 20210249E002 OPERATOR: Okbay CONE ID: DDG1351 TEST DATE: 4/9/2024 10:55:33 AM PREDRILL: 0 ft BACKFILL: 20% Bentonite slurry & Chips SURFACE PATCH: Cold Patch TOTAL DEPTH: 34.121 ft Depth (ft) Tip COR (tsf) 0 10000 5 10 15 20 25 30 35 40 Sleeve Stress (tsf) 08 F.Ratio (%) 0 5 Pore Pressure (psi) -5 35 SBT FR (RC 1983) 1 sensitive fine grained 2 organic material 3 clay 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *SBT/SPT CORRELATION: UBC-1983 0 12 SPT (blows/ft) 0 120 CPT-02 CPT Contractor: In SItu Engineering CUSTOMER: AES LOCATION: Renton JOB NUMBER: 20210249E002 OPERATOR: Okbay CONE ID: DDG1351 TEST DATE: 4/9/2024 12:48:08 PM PREDRILL: 0 ft BACKFILL: 20% Bentonite slurry & Chips SURFACE PATCH: Cold Patch TOTAL DEPTH: 25.262 ft Depth (ft) Tip COR (tsf) 0 10000 5 10 15 20 25 30 F.Ratio (%) 0 5 Pore Pressure (psi) -10 15 SBT FR (RC 1983) 1 sensitive fine grained 2 organic material 3 clay 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *SBT/SPT CORRELATION: UBC-1983 0 12 SPT (blows/ft) 0 100 Seismic Velocity (ft/s) 0 1800 HOLE NUMBER: CPT-02 OPERATOR: Okbay CUSTOMER: LOCATION: Renton JOB NUMBER: 20210249E002 CPT Contractor: In SItu Engineering CONE ID: DDG1351 TEST DATE: 4/9/2024 12:48:08 PM PREDRILL0 ft BACKFILL: 20% Bentonite slurry & Chips SURFACE PATCH: Cold Patch HOLE NUMBER: CPT-02 Depth 3.77ft Ref* Arrival 6.68mS Velocity* Depth 7.05ft Ref 3.77ft Arrival 9.80mS Velocity 937.72ft/S Depth 13.45ft Ref 7.05ft Arrival 13.67mS Velocity 1597.86ft/S Depth 20.01ft Ref 13.45ft Arrival 19.80mS Velocity 1056.58ft/S 0 10 20 30 40 50 60 70 80 90 100 Depth 25.26ft Ref 20.01ft Arrival 25.55mS Velocity 908.07ft/S Time (mS) Hammer to Rod String Distance (ft): 2.62 * = Not Determined CPT-03 CPT Contractor: In SItu Engineering CUSTOMER: AES LOCATION: Renton JOB NUMBER: 20210249E002 OPERATOR: Okbay CONE ID: DDG1351 TEST DATE: 4/9/2024 1:59:11 PM PREDRILL: 0 ft BACKFILL: 20% Bentonite slurry & Chips SURFACE PATCH: Cold Patch TOTAL DEPTH: 20.505 ft Depth (ft) Tip COR (tsf) 0 10000 5 10 15 20 25 30 35 40 Sleeve Stress (tsf) 08 F.Ratio (%) 0 5 Pore Pressure (psi) -5 35 SBT FR (RC 1983) 1 sensitive fine grained 2 organic material 3 clay 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *SBT/SPT CORRELATION: UBC-1983 0 12 SPT (blows/ft) 0 120 APPENDIX C Historical Exploration Logs (AESI, 1999, 2009, 2024) 0 5 10 15 20 25 30 35 100% 60% 50% 40% 1 2 3 4 0800 0845 0823 FillCuttings are brownish gray, gravelly, silty, SAND; occasional organics (fine wood); rounded gravel; driller reports caving to 10 feet (SM). Holocene AlluviumCuttings are gray, silty, fine to medium SAND, trace coarse sand (SM). Chatter and bouncing; driller reports increased caved material at 20 feet. Cuttings are gray, medium to coarse sandy, SILT; occasional gravel; organics (roots); drill action smoothes (ML). Cuttings are gray, medium to coarse sandy, SILT; occasional broken gravel (ML). Driller notes increased drill action at 30 feet; driller adds water and bentonite. Chatter and bouncing increase. Geothermal test loop was not installed; hole backfilled with bentonite grout. Associated Earth Sciences, Inc. Exploration Boring GTL-1 Renton High School Replacement Renton, Washington Start Date: 10/1/24 Logged By: RPW 20210249E002 Ending Date: 10/7/2024 Approved By: JHS Driller/Equipment:Gregory/Track Mounted Mud RotaryHole Dia. (in):6 Total Depth (ft):70Ground Surface Elevation (ft):»32 Water Level Elevation (ft):N/A (mud rotary)Groundwater Depth ATD (ft): N/A (mud rotary) Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 1 of 2 40 45 50 55 60 65 70 100% 20% 0% 100% 20% 5 6 7 0833 1234 1305 0800 1430 1100 1445 Cuttings are grayish brown to orangish brown, silty, coarse SAND; occasional fine to medium sand; broken gravel (SM). Loud chatter; driller reports bouncing; lost a large amount of water (»2,200 gallons); driller adds water and bentonite. Driller notes loss in circulation; no sample recovered; driller decides to advance casing to combat caving and water loss (»3,200 gallons). Cuttings are grayish brown, silty, medium to coarse SAND, trace fine sand; gravel content understated by lack of circulation (SM). Cuttings are gray, SILT, trace fine sand; driller notes no circulation, losing water rapidly; gravel content understated by lack of circulation (ML). Abandoned hole due to difficult gravelly drilling conditions and loss of water/ drilling fluid circulation. Driller efforts to advance from 50 to 70 feet took 2 days with two separate drill rigs. Associated Earth Sciences, Inc. Exploration Boring GTL-1 Renton High School Replacement Renton, Washington Start Date: 10/1/24 Logged By: RPW 20210249E002 Ending Date: 10/7/2024 Approved By: JHS Driller/Equipment:Gregory/Track Mounted Mud RotaryHole Dia. (in):6 Total Depth (ft):70Ground Surface Elevation (ft):»32 Water Level Elevation (ft):N/A (mud rotary)Groundwater Depth ATD (ft): N/A (mud rotary) Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 2 of 2 0 5 10 15 20 25 30 35 N/A N/A N/A N/A 1 2 3 4 2/20 0934 0941 0948 0956 1015 1026 1035 Topsoil/Sod - 3 inches FillDriller uses air rotary to advance casing down to 100 feet. Cuttings are brown, fine sandy, SILT; occasional orange oxidation staining; driller notes easy drilling (ML). Holocene Alluvium Dark brown, silty, gravelly, medium to coarse SAND, silt coats gravel; broken gravel (SM-GM). Driller reports heaving sand and gravel within the casing. Driller reports heaving sand and gravel at 22 feet; increase in difficult drilling. Wet, brown, gravelly, fine to medium SAND, trace coarse sand; broken gravel (SP-GP). Increased drill chatter and bouncing; cuttings brown at 25 feet. Cuttings are wet, brown, silty, fine to medium SAND; occasional organics (1/4 to 1/2-inch wood debris); 1-inch diameter Centennial CenFuse IPS SDR11 polyethylene flexible pipe loop with fused connector at baseGeothermal loop extends from 0 to 301 feetBentonite grout 0 to 301 feet Associated Earth Sciences, Inc. Exploration Boring GTL-2 Renton High School Replacement Renton, Washington Start Date: 2/20/25 Logged By: RPW 20210249E002 Ending Date: 2/24/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):301Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»12.5Groundwater Depth ATD (ft): 20 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 1 of 9 40 45 50 55 60 65 70 N/A N/A N/A N/A 5 6 7 8 1043 1051 1106 1113 1145 1155 1241 1258 broken gravel (SM). Increasing chatter and bouncing from 38 to 110 feet. Increased groundwater coming out of the cuttings; color is oxidized orange brown; drill bit grinding on gravel. Cuttings are wet, oxidized brown, gravelly, medium to coarse SAND, fine sand; broken gravel; water color changing from light brown to brown/oxidized orange brown; increasing bouncing and drill chatter (SP). Drill bouncing on gravel at 48 feet; water becomes dark brown). Increasing chatter; bouncing on gravel at 53 and 55 feet. Cuttings are wet, gray to dark brownish gray, medium to coarse sandy, GRAVEL; broken gravel; water is dark brown or brown (GP). Jumping on gravel; hard drilling; increased chatter at 62 feet. Cuttings are as above; increased chatter; slow advancing. Water is oxidized brown color. Associated Earth Sciences, Inc. Exploration Boring GTL-2 Renton High School Replacement Renton, Washington Start Date: 2/20/25 Logged By: RPW 20210249E002 Ending Date: 2/24/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):301Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»12.5Groundwater Depth ATD (ft): 20 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 2 of 9 75 80 85 90 95 100 105 N/A N/A N/A 100% 80% 70% 9 10 11 1325 1333 1411 1421 2/20 1530 0947 2/21 Cuttings are as above; water is oxidized brown. Drill chatter and bouncing on cobble or gravel at 82 feet. Drill chatter decreases from 84 to 90 feet. Cuttings are as above; gravel content decreases; sand size decreases to fine to medium sand with occasional coarse sand and gravel. Water becomes dark brown and grain size of sand and gravel increases at 92 feet.Drill chatter and action increasing at 93 feet. Driller reports bouncing on gravel or cobble; chatter increases and drill action increases 96 to 99 feet. Driller switches to a tricone bit and a mud-rotary configuration. Driller reports no cuttings due to drilling in gravel and cobbles and loss of circulation.Driller reports caving around 100 to 110 feet within the borehole. Bouncing on gravel at 107 feet; driller reports encountering silty deposit at 108 feet. Tukwila Formation: Siltstone ? Associated Earth Sciences, Inc. Exploration Boring GTL-2 Renton High School Replacement Renton, Washington Start Date: 2/20/25 Logged By: RPW 20210249E002 Ending Date: 2/24/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):301Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»12.5Groundwater Depth ATD (ft): 20 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 3 of 9 110 115 120 125 130 135 140 145 70% 70% 60% 50% 30% 30% 10% 12 13 14 15 1015 1040 1114 1115 1219 1220 1317 1319 Cuttings are light gray, fine sandy, SILT, trace coarse sand (ML). Cuttings are dark gray, fine sandy, SILT, driller reports increase in torque from 107 feet to 125 feet; driller pulled the rods at 125 feet to switch back to the tricone bit; driller reports difficulty getting through the hard silt with drag bit (ML). Cuttings are as above; trace gravel. Driller states torque and chatter increasing at 137 feet and bouncing on gravel. Cuttings are as above. Associated Earth Sciences, Inc. Exploration Boring GTL-2 Renton High School Replacement Renton, Washington Start Date: 2/20/25 Logged By: RPW 20210249E002 Ending Date: 2/24/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):301Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»12.5Groundwater Depth ATD (ft): 20 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 4 of 9 150 155 160 165 170 175 180 16 17 18 19 2/21 1450 0737 2/24 0751 0753 0800 0801 0808 0809 Driller began to trip out. Drill action increases; difficult drilling from 153 to 177. Cuttings are brownish gray, SILT, trace fine sand, trace coarse sand; relatively easy drilling (ML). Drill action smooth from 160 to 170 feet. Cuttings are gray, SILT, fine to very fine sand, trace broken coarse sand and gravel (ML). Cuttings are as above; fine sand content increases to very fine to fine sandy, SILT (ML). Smooth drilling from 180 to 184 feet. Associated Earth Sciences, Inc. Exploration Boring GTL-2 Renton High School Replacement Renton, Washington Start Date: 2/20/25 Logged By: RPW 20210249E002 Ending Date: 2/24/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):301Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»12.5Groundwater Depth ATD (ft): 20 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 5 of 9 185 190 195 200 205 210 215 10% 30% 30% 60% 60% 60% 60% 20 21 22 0816 0817 0956 0957 1014 1015 Drill action increased; lost circulation into formation at 184 feet; driller adds water and polymer.Cuttings are gray, fine sandy, SILT; occasional gravel and broken gravel. Drill action smooth 190 to 192 feet. Driller reports losing circulation at 192 feet; drill action/ stuck rods; chatter increases; driller increased saw dust due to loss in water; tried again but lost all the water within 10 minutes at bottom. Driller states they will trip in and out to build a "layer of cake" of saw dust and polymer within the borehole. Cuttings are gray, SILT, trace very fine sand; broken gravel; poor recovery; easy drill action (ML). Driller reports rough drilling; increased chatter. Cuttings are light gray, SILT, trace fine sand, broken gravel (ML). Associated Earth Sciences, Inc. Exploration Boring GTL-2 Renton High School Replacement Renton, Washington Start Date: 2/20/25 Logged By: RPW 20210249E002 Ending Date: 2/24/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):301Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»12.5Groundwater Depth ATD (ft): 20 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 6 of 9 220 225 230 235 240 245 250 60% 60% 60% 60% 60% 60% 60% 23 24 25 26 1027 1028 1038 1038 1100 1100 1110 1112 Easy drilling; contractor reports jumping on gravel 222 to 223 feet. Cuttings are light gray to bluish gray, silty, medium SAND; sand comprised of broken gravel and coarse sand; easy drill action; driller reports drill torque increased but no loss in drilling fluid (SM). Cuttings are grayish, brown to gray, fine sandy, SILT, trace coarse sand; easy but slow drilling (ML).Driller reports hard, slow drilling. Cuttings are as above. Drilling slow; driller reports hard unit. Associated Earth Sciences, Inc. Exploration Boring GTL-2 Renton High School Replacement Renton, Washington Start Date: 2/20/25 Logged By: RPW 20210249E002 Ending Date: 2/24/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):301Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»12.5Groundwater Depth ATD (ft): 20 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 7 of 9 255 260 265 270 275 280 285 290 27 28 29 30 1147 1149 1220 1222 1307 1308 1338 1340 Increase in coarse sand. Driller reports minimal fluid loss; slow drilling. Cuttings are as above. Slow drilling at 272 feet. Cuttings are as above. Slow drilling 280 to 290 feet. Very slow drilling 284 to 288 feet. Cutting fluid remains a grayish brown; driller adds water. Associated Earth Sciences, Inc. Exploration Boring GTL-2 Renton High School Replacement Renton, Washington Start Date: 2/20/25 Logged By: RPW 20210249E002 Ending Date: 2/24/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):301Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»12.5Groundwater Depth ATD (ft): 20 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 8 of 9 295 300 305 310 315 320 325 60% 50% 2/24 1358 Cuttings are dark gray, silty, medium SAND; sand consists of broken gravel and coarse sand (SM). Driller reports increase in drill action and loss of drilling fluid; driller adds polymer, sawdust, and water. Groundwater encountered at 20 feet ATD. Driller completed the borehole on 2/24/25, but due to caving at approximately 110 feet BGS, the driller advanced 10 more feet of casing down to a total depth of 110 feet. The driller then advanced their drill rods down to 301 feet and back out before successfully installing the geothermal test loop on 2/ 25/25. Associated Earth Sciences, Inc. Exploration Boring GTL-2 Renton High School Replacement Renton, Washington Start Date: 2/20/25 Logged By: RPW 20210249E002 Ending Date: 2/24/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):301Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»12.5Groundwater Depth ATD (ft): 20 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 9 of 9 0 5 10 15 20 25 30 35 1 2 3 4 2/26 0926 0949 1052 1100 1108 1113 1119 Asphalt - 4 inches FillCuttings are brownish, sandy, SILT; occasional organics (leaves, moss and sticks from asphalt); driller began driving casing with an underreamer bit (ML). Holocene Alluvium Grayish brown, silty, fine to medium SAND; trace rounded gravel (SM). Silt content increases; sand size decreases; brown, medium to coarse sandy, SILT; occasional fine gravel (ML). Easy drilling 20 to 30 feet. Driller reports increased drill action at 25 feet. Cuttings are brownish, sandy, SILT, some fine gravel (ML). Cuttings become dark gray, gravelly, medium to coarse SAND; silt coating sand and gravel clasts; broken gravel; trace organics (1 to 2 inch wood debris); relatively rounded gravel (SP-SM). Geothermal test was not installed; hole backfilled with bentonite grout. Associated Earth Sciences, Inc. Exploration Boring GTL-3 Renton High School Replacement Renton, Washington Start Date: 2/26/25 Logged By: RPW 20210249E002 Ending Date: 2/27/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):125Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»2Groundwater Depth ATD (ft): 30 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 1 of 4 40 45 50 55 60 65 70 5 6 7 8 1124 1135 1141 1149 1156 1203 1210 1216 Cuttings become brown; relatively easy drilling 40 to 45 feet.Cuttings are gray, silty, fine to medium SAND, trace coarse sand; broken gravel; gravel rounded (SM). Cuttings increase with water; driller reports heaving conditions; moderate drilling difficulty. Cuttings water becomes oxidized brown. Cuttings are dark grayish brown, gravelly, medium to coarse SAND, trace silt; broken gravel and coarse sand (SP-GP). Cuttings become gray, sandy, SILT; interbed? (ML). Cuttings become gray with decrease in gravel; relatively easy drilling from 60 to 70 feet but low sample recovery. Cuttings are gray, fine sandy, SILT, trace broken gravel (ML). Cuttings are dark oxidized orangish gray, gravelly, medium to coarse SAND; broken gravel and sand; angular sand; cuttings water is oxidized brown; driller states heaving conditions; rough drilling from 70 feet; Associated Earth Sciences, Inc. Exploration Boring GTL-3 Renton High School Replacement Renton, Washington Start Date: 2/26/25 Logged By: RPW 20210249E002 Ending Date: 2/27/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):125Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»2Groundwater Depth ATD (ft): 30 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 2 of 4 75 80 85 90 95 100 105 9 10 11 1231 1237 1301 1312 1338 1343 2/26 increased drill action and chatter (SP). Cuttings are oxidized brown gray, medium to coarse sandy, GRAVEL; moderately difficult drilling to 80 feet; increased chatter (GP). Chatter and drill action increases from 80 to 90 feet. Cuttings are brownish dark gray, gravelly, medium to coarse SAND to sandy, GRAVEL; broken gravel and sand (SP-GP). Driller chatter, action, and difficulty increases. Cuttings are as above. Cuttings are brown gray; increased chatter and drill action. Cuttings are dark gray, medium to coarse, sandy, fine GRAVEL; broken coarse sand and gravel; cuttings water is light/tan brown (GP). Associated Earth Sciences, Inc. Exploration Boring GTL-3 Renton High School Replacement Renton, Washington Start Date: 2/26/25 Logged By: RPW 20210249E002 Ending Date: 2/27/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):125Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»2Groundwater Depth ATD (ft): 30 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 3 of 4 110 115 120 125 130 135 140 145 12 13 1500 0832 2/27 0940 0942 2/27 Driller reports broken shoe; will begin mud rotary drilling due to broken shoe; begins advance with tricone bit; increased chatter at 112 feet. No sample recovered due to lack of circulation. Difficult drilling conditions; driller reports increased chatter and bit bouncing on gravel at 120 feet. Driller reports caving gravel could cause issues removing drill rod and abandons the hole. Groundwater encountered at 30 feet. Associated Earth Sciences, Inc. Exploration Boring GTL-3 Renton High School Replacement Renton, Washington Start Date: 2/26/25 Logged By: RPW 20210249E002 Ending Date: 2/27/25 Approved By: JHS Driller/Equipment:GeoTility/Pickup Mounted Air/Mud RotaryHole Dia. (in):4 Total Depth (ft):125Ground Surface Elevation (ft):»32 Water Level Elevation (ft):»2Groundwater Depth ATD (ft): 30 Datum:NAVD 88 De p t h ( f t ) Fl u i d V o l u m e Ru n N o . & L e n g t h %R e c o v e r y Ru n T i m e Sa m p l e Ot h e r T e s t s & S a m p l e s Gr a p h i c Sy m b o l Description Wa t e r L e v e l Well Construction 20 2 1 0 2 4 9 E 0 0 2 4/ 2 5 / 2 0 2 5 Sheet: 4 of 4 APPENDIX D Hydrograph ASSOCIATED EARTH SCIENCES, INC. Groundwater Hydrograph Renton High School Replacement Renton, Washington AESI Project No. 20210249E002 06/2025 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 18 19 20 21 22 23 24 25 26 27 28 04 / 0 1 / 2 4 05 / 2 1 / 2 4 07 / 1 0 / 2 4 08 / 2 9 / 2 4 10 / 1 8 / 2 4 12 / 0 7 / 2 4 01 / 2 6 / 2 5 03 / 1 7 / 2 5 05 / 0 6 / 2 5 06 / 2 5 / 2 5 08 / 1 4 / 2 5 Ra i n f a l l ( i n c h e s ) Ap p r o x i m a t e G r o u n d w a t e r E l e v a t i o n ( f e e t ) EB-1W EB-1W Dl.EB-3W EB-3W DL EB-6W EB-6W Dl.Daily Rainfall Note: Black and white reproduction of this color original may reduce its effectiveness and lead to incorrect interpretation. Note: Well elevations are based on 2021 King County LIDAR contour elevations. APPENDIX E Laboratory Test Results Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 0.8 2.4 4.5 21.1 71.2 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: Onsite Sample Number: EB-1W Depth: 5' Client: Project: Project No:Figure sandy SILT trace gravel 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 99.2 97.7 96.8 94.1 92.3 89.4 78.3 71.2 68.9 NP NV ML A-4(0) 0.2603 0.2007 5-2-2024 5-6-2024 FEW BCY/BD 4-9-2024 Renton School District No. 403 Renton High School 20210249 E002 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 9.7 3.2 52.3 29.3 5.5 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: Onsite Sample Number: EB-1W Depth: 35' Client: Project: Project No:Figure SAND some gravel some silt 3/4" 5/8" 1/2" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 98.2 96.3 94.4 90.3 87.7 87.1 76.0 34.8 16.0 8.4 5.5 4.8 NP NV SP-SM A-1-b 4.4290 1.1970 0.6359 0.5454 0.3854 0.2391 0.1757 3.62 1.33 5-2-2024 5-6-2024 FEW BCY/BD 4-9-2024 Renton School District No. 403 Renton High School 20210249 E002 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 8.7 5.8 14.0 48.3 23.2 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: Onsite Sample Number: EB-2 Depth: 2.5 Client: Project: Project No:Figure silty SAND some gravel 5/8" 1/2" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 99.1 96.9 91.3 86.5 85.5 79.0 71.5 57.3 33.4 23.2 18.5 NP NV SM A-2-4(0) 3.9921 1.8638 0.2678 0.2143 0.1337 5-2-2024 5-6-2024 FEW BCY/BD 4-10-2024 Renton School District No. 403 Renton High School 20210249 E002 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 6.5 2.7 7.6 58.5 24.7 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: Onsite Sample Number: EB-3W Depth: 2.5' Client: Project: Project No:Figure silty SAND some gravel 5/8" 1/2" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 97.0 95.6 93.5 91.8 90.8 87.2 83.2 74.8 42.1 24.7 21.8 NP NV SM A-2-4(0) 1.7106 0.6009 0.1961 0.1700 0.1094 5-2-2024 5-6-2024 FEW BCY/BD 4-10-2024 Renton School District No. 403 Renton High School 20210249 E002 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 1.3 7.5 8.3 45.3 37.6 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: Onsite Sample Number: EB-3W Depth: 7.5' Client: Project: Project No:Figure very silty SAND trace gravel 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 98.7 93.1 91.2 85.3 82.9 74.6 50.6 37.6 33.4 NP NV SM A-4(0) 1.7935 0.7866 0.1833 0.1478 5-2-2024 5-6-2024 FEW BCY/BD 4-10-2024 Renton School District No. 403 Renton High School 20210249 E002 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 6.1 29.0 12.2 17.5 21.7 13.5 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: Onsite Sample Number: EB-4 Depth: 0' Client: Project: Project No:Figure very gravelly silty SAND 1" 3/4" 5/8" 1/2" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 93.9 91.4 86.6 78.2 64.9 54.5 52.7 43.0 35.2 28.5 19.0 13.5 11.4 NP NV SM A-1-b 14.6977 12.0069 3.4925 1.5709 0.2751 0.0988 5-2-2024 5-6-2024 FEW BCY/BD 4-9-2024 Renton School District No. 403 Renton High School 20210249 E002 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0 0.0 0.0 1.5 8.6 72.3 17.6 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: Onsite Sample Number: EB-5 Depth: 10' Client: Project: Project No:Figure silty SAND #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 98.7 98.5 97.0 89.9 47.5 28.0 17.6 15.0 NP NV SM A-2-4(0) 0.4285 0.3938 0.2928 0.2590 0.1645 5-2-2024 5-6-2024 FEW BCY/BD 4-11-2024 Renton School District No. 403 Renton High School 20210249 E002 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 11.1 38.5 10.6 19.2 14.9 5.7 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: Onsite Sample Number: EB-6W Depth: 15' Client: Project: Project No:Figure very sandy GRAVEL some silt 1.5" 1" 3/4" 5/8" 1/2" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 92.6 88.9 75.8 69.9 62.2 50.4 41.4 39.8 31.6 20.6 12.4 8.5 5.7 5.0 NP NV GP-GM A-1-a 20.9579 17.9683 8.7323 4.6103 0.7568 0.3037 0.1918 45.52 0.34 5-2-2024 5-6-2024 FEW BCY/BD 4-11-2024 Renton School District No. 403 Renton High School 20210249 E002 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) APPENDIX F Liquefaction Analysis Results Li q u e f y P r o C i v i l T e c h S o f t w ar e U S A w w w . c i v i l t e c h . c o m CivilTech Corporation LIQUEFACTION ANALYSIS Renton High School Plate A-1 Hole No.=EB-1W Water Depth=5 ft Surface Elev.=32 Magnitude=7.0 Acceleration=0.677g (ft)0 10 20 30 40 50 60 70 40 125 12 3 105 35 2 100 70 2 100 70 4 105 30 2 100 70 6 105 70 8 110 5 14 115 5 15 115 5 27 125 5 42 125 2 41 125 2 Fill Black River Alluvium Cedar River Alluvium Raw Unit FinesSPT Weight %Shear Stress Ratio CRR CSR fs1 Shaded Zone has Liquefaction Potential 01 Soil DescriptionFactor of Safety051Settlement Saturated Unsaturat. S = 11.04 in. 0 (in.) 50 fs1=1 Li q u e f y P r o C i v i l T e c h S o f t w ar e U S A w w w . c i v i l t e c h . c o m CivilTech Corporation LIQUEFACTION ANALYSIS Renton High School Plate A-1 Hole No.=EB-2 Water Depth=5 ft Surface Elev.=34 Magnitude=7.0 Acceleration=0.677g (ft)0 10 20 30 40 50 60 70 17 120 25 7 110 25 4 105 10 5 105 90 3 105 90 4 105 90 29 125 5 35 125 5 7 110 5 22 120 25 31 125 10 53 125 10 34 125 25 Fill Black River Alluvium Cedar River Alluvium Raw Unit FinesSPT Weight %Shear Stress Ratio CRR CSR fs1 Shaded Zone has Liquefaction Potential 01 Soil DescriptionFactor of Safety051Settlement Saturated Unsaturat. S = 6.97 in. 0 (in.) 10 fs1=1 Li q u e f y P r o C i v i l T e c h S o f t w ar e U S A w w w . c i v i l t e c h . c o m CivilTech Corporation LIQUEFACTION ANALYSIS Renton High School Plate A-1 Hole No.=EB-3W Water Depth=5 ft Surface Elev.=38 Magnitude=7.0 Acceleration=0.677g (ft)0 10 20 30 40 50 60 70 17 115 25 4 105 25 2 100 90 7 110 50 16 115 25 4 110 10 26 125 25 32 125 25 34 125 5 17 120 5 41 125 5 20 120 5 44 125 7 Fill Black River Alluvium Cedar River Alluvium Raw Unit FinesSPT Weight %Shear Stress Ratio CRR CSR fs1 Shaded Zone has Liquefaction Potential 01 Soil DescriptionFactor of Safety051Settlement Saturated Unsaturat. S = 7.12 in. 0 (in.) 10 fs1=1 Li q u e f y P r o C i v i l T e c h S o f t w ar e U S A w w w . c i v i l t e c h . c o m CivilTech Corporation LIQUEFACTION ANALYSIS Renton High School Plate A-1 Hole No.=EB-4 Water Depth=5 ft Surface Elev.=34 Magnitude=7.0 Acceleration=0.677g (ft)0 10 20 30 40 50 60 70 21 120 25 2 100 25 2 100 60 3 105 80 4 105 70 7 105 10 38 125 5 41 125 5 19 120 10 35 125 10 43 125 10 33 125 5 Fill Black River Alluvium Cedar River Alluvium Raw Unit FinesSPT Weight %Shear Stress Ratio CRR CSR fs1 Shaded Zone has Liquefaction Potential 01 Soil DescriptionFactor of Safety051Settlement Saturated Unsaturat. S = 6.82 in. 0 (in.) 10 fs1=1 Li q u e f y P r o C i v i l T e c h S o f t w ar e U S A w w w . c i v i l t e c h . c o m CivilTech Corporation LIQUEFACTION ANALYSIS Renton High School Plate A-1 Hole No.=EB-5 Water Depth=5 ft Surface Elev.=34 Magnitude=7.0 Acceleration=0.677g (ft)0 10 20 30 40 50 60 70 21 120 25 5 105 25 2 100 70 7 110 25 12 110 25 24 125 10 31 125 5 43 125 3 36 125 5 52 125 5 43 125 5 51 125 25 15 120 10 Fill Black River Alluvium Cedar River Alluvium Raw Unit FinesSPT Weight %Shear Stress Ratio CRR CSR fs1 Shaded Zone has Liquefaction Potential 01 Soil DescriptionFactor of Safety051Settlement Saturated Unsaturat. S = 3.90 in. 0 (in.) 10 fs1=1 Li q u e f y P r o C i v i l T e c h S o f t w ar e U S A w w w . c i v i l t e c h . c o m CivilTech Corporation LIQUEFACTION ANALYSIS Renton High School Plate A-1 Hole No.=EB-6W Water Depth=5 ft Surface Elev.=36 Magnitude=7.0 Acceleration=0.677g (ft)0 10 20 30 40 50 60 70 11 110 25 14 115 25 21 120 25 37 125 5 44 125 5 19 120 5 37 125 5 49 125 5 44 125 10 50 125 3 35 125 10 26 125 5 22 120 5 Fill Cedar River Alluvium Raw Unit FinesSPT Weight %Shear Stress Ratio CRR CSR fs1 Shaded Zone has Liquefaction Potential 01 Soil DescriptionFactor of Safety051Settlement Saturated Unsaturat. S = 2.09 in. 0 (in.) 10 fs1=1 Li q u e f y P r o C i v i l T e c h S o f t w ar e U S A w w w . c i v i l t e c h . c o m CivilTech Corporation LIQUEFACTION ANALYSIS Renton High School Plate A-1 Hole No.=CPT-01 Water Depth=5 ft Surface Elev.=32 Magnitude=7.0 Acceleration=0.677g (ft)0 5 10 15 20 25 30 35 Fill Black River Alluvium Cedar River Alluvium Shear Stress Ratio CRR CSR fs1 Shaded Zone has Liquefaction Potential 01 Soil DescriptionFactor of Safety051Settlement Saturated Unsaturat. S = 1.79 in. 0 (in.) 10 fs1=1 Li q u e f y P r o C i v i l T e c h S o f t w ar e U S A w w w . c i v i l t e c h . c o m CivilTech Corporation LIQUEFACTION ANALYSIS Renton High School Plate A-1 Hole No.=CPT-02 Water Depth=5 ft Surface Elev.=36 Magnitude=7.0 Acceleration=0.677g (ft)0 5 10 15 20 25 30 35 Fill Cedar River Alluvium Shear Stress Ratio CRR CSR fs1 Shaded Zone has Liquefaction Potential 01 Soil DescriptionFactor of Safety051Settlement Saturated Unsaturat. S = 0.85 in. 0 (in.) 1 fs1=1 Li q u e f y P r o C i v i l T e c h S o f t w ar e U S A w w w . c i v i l t e c h . c o m CivilTech Corporation LIQUEFACTION ANALYSIS Renton High School Plate A-1 Hole No.=CPT-03 Water Depth=5 ft Surface Elev.=34 Magnitude=7.0 Acceleration=0.677g (ft)0 5 10 15 20 25 30 35 Fill Black River Alluvium Shear Stress Ratio CRR CSR fs1 Shaded Zone has Liquefaction Potential 01 Soil DescriptionFactor of Safety051Settlement Saturated Unsaturat. S = 1.35 in. 0 (in.) 10 fs1=1 APPENDIX G Shear Wave Velocity Survey (WSG, 2020) WASHINGTON 2019–2021 SCHOOL SEISMIC SAFETY PROJECT SITE CLASS ASSESSMENT See Washington Geological Survey Open File Report 2019-01 for more information. RENTON HIGH SCHOOL Location of seismic array at the school campus. Liquefaction Moderate to high RENTON SCHOOL DISTRICT, KING COUNTY, WA WHAT IS SITE CLASS? Site class estimates how local soils amplify earthquake- induced ground shaking, and is based on how fast seismic (shear) waves travel through the upper 30 m (100 ft) of the soil (Vs30). Site class has been approximated for the entire State of Washington, but these predictions aren’t always accurate where geology is complex. The site class measured for this project accounts for geologic complexity and is therefore more accurate. HOW DID WE MEASURE SITE CLASS? On October 15, 2020, a team from the Washington Geological Survey conducted a seismic survey at Renton High School. We measured Vs30 by laying out 48 geophones (ground motion sensors) in a 94 m (308 ft) array. Then we conducted (1) an active survey in which a sledgehammer was struck against the ground to generate seismic waves; and (2) a passive survey where we measured ambient seismic noise. These surveys let us calculate Vs30 at the center of the array, which is then correlated to site class using the table below. It is generally accurate to assume the site class is the same under the array and the school. WHAT DID WE LEARN? □The school is built on stiff soil, which would amplify ground shaking relative to rock. □Site class is within the predicted site class of D–E.WHAT SOILS ARE UNDER THE SCHOOL? The school is sitting on urban or industrial land modified by widespread or discontinuous artificial fill. GEOLOGIC HAZARDS AT THE SCHOOL Ground Shaking Violent MEASURED SITE CLASS D Site class Description Vs30 (m/sec) Ground shaking amplification A Hard rock >1,500 Low B Rock 760–1,500 C Soft rock or very dense soil 360–760 D Stiff soil 180–360 E Soft soil <180 High TECHNICAL OVERVIEW OF RESULTS QUESTIONS?Washington Department of Natural Resources—WA Geological Survey geology@dnr.wa.gov • 360.902.1450 • https://www.dnr.wa.gov/geology RENTON HIGH SCHOOL—ICOS# 21354 This section provides a technical overview of the geophysical methods and results of the seismic site characterization. DISPERSION CURVE The term dispersion image refers to the image of phase velocity versus frequency of a record. Dispersion curve refers to the manually picked fundamental mode in a dispersion image. The multi-channel analysis of surface wave (MASW) dispersion images from the forward and reverse directions are poor quality, but the fundamental mode can be picked with some confidence. However, the microtremor analysis method (MAM) dispersion image is excellent quality, so that the fundamental mode can be picked with high confidence. MAM and the forward and reverse MASW dispersion curves correlate well, depicting similar trends. Therefore the three dispersion curves are combined into a single model. VELOCITY MODEL An initial model was generated using the 1/3 wavelength approximation and the combined dispersion curves. The initial model had an RMSE of 12.9 percent. The inversion was carried out for ten iterations and resulted in a final model with an RMSE of 4.7 percent. The final model is unconstrained in the top 1 m (3 ft), and below this shows rapidly increasing velocity to 6 m (20 ft), then generally increasing velocity down to 30 m (100 ft). Our best Vs30 measurement is 272 m/sec, which places the site solidly in the D site class. This is within the predicted site class of D–E. Final inverted velocity model with measured dispersion curve and modeled dispersion curve. The equation used to calculate the average shear wave velocity (Vs) for the upper 30 m is shown in the upper right corner. di = thickness of any layer between 0 and 30 m. Vsi = shear wave velocity in m/sec of the layer. APPENDIX H Wellhead Protection Zone Map City of Renton GIS Mapping for Wellhead Protection Area Zones Proposed Renton High School Replacement/Expansion Area Technical Information Report New Renton High School Project No. 2230388.10 Appendix C Flow Control Calculations WWHM2012 PROJECT REPORT APPENDIX C FLOW CONTROL CALCULATIONS Flow control 9/11/2025 1:32:03 PM Page 2 General Model Information WWHM2012 Project Name:Flow control Site Name: Site Address: City: Report Date:9/11/2025 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2025/05/13 Version:4.3.2 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year Low Flow Threshold for POC2:50 Percent of the 2 Year High Flow Threshold for POC2:50 Year Low Flow Threshold for POC3:50 Percent of the 2 Year High Flow Threshold for POC3:50 Year Flow control 9/11/2025 1:32:03 PM Page 3 Landuse Basin Data Predeveloped Land Use TDA 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.31 Pervious Total 0.31 Impervious Land Use acre ROADS FLAT 0.96 Impervious Total 0.96 Basin Total 1.27 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 1 POC 1 Flow control 9/11/2025 1:32:03 PM Page 4 TDA 2 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 10.57 Pervious Total 10.57 Impervious Land Use acre ROADS FLAT 17.82 Impervious Total 17.82 Basin Total 28.39 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 2 POC 2 Flow control 9/11/2025 1:32:03 PM Page 5 Basin 3 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 2.08 Pervious Total 2.08 Impervious Land Use acre ROADS FLAT 4.77 Impervious Total 4.77 Basin Total 6.85 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 3 POC 3 Flow control 9/11/2025 1:32:03 PM Page 6 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.41 Pervious Total 0.41 Impervious Land Use acre ROADS FLAT 0.43 Impervious Total 0.43 Basin Total 0.84 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 1 POC 1 Flow control 9/11/2025 1:32:03 PM Page 7 Basin 2A Bypass:Yes GroundWater:No Pervious Land Use acre C, Lawn, Flat 5.82 Pervious Total 5.82 Impervious Land Use acre ROADS FLAT 16.63 Impervious Total 16.63 Basin Total 22.45 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 2 POC 2 Flow control 9/11/2025 1:32:03 PM Page 8 Basin 2B Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.94 Pervious Total 0.94 Impervious Land Use acre ROADS FLAT 5.91 Impervious Total 5.91 Basin Total 6.85 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Tank 2B Tank 2B Flow control 9/11/2025 1:32:03 PM Page 9 Basin 3 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 1.3 Pervious Total 1.3 Impervious Land Use acre ROADS FLAT 5.06 Impervious Total 5.06 Basin Total 6.36 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 3 POC 3 Flow control 9/11/2025 1:32:03 PM Page 10 Routing Elements Predeveloped Routing Flow control 9/11/2025 1:32:03 PM Page 11 Mitigated Routing Tank 2B Dimensions Depth:5 ft. Tank Type:Circular Diameter:5 ft. Length:2055 ft. Discharge Structure Riser Height:4.5 ft. Riser Diameter:24 in. Notch Type:Rectangular Notch Width:1.000 ft. Notch Height:0.750 ft. Orifice 1 Diameter:3.250 in.Elevation:0.5 ft. Element Outlets: Outlet 1 Outlet 2 Outlet Flows To: Tank Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.000000 0.000000 0.000 0.000 0.0556 0.049451 0.001836 0.000 0.000 0.1111 0.069540 0.005174 0.000 0.000 0.1667 0.084684 0.009474 0.000 0.000 0.2222 0.097221 0.014536 0.000 0.000 0.2778 0.108063 0.020245 0.000 0.000 0.3333 0.117678 0.026521 0.000 0.000 0.3889 0.126348 0.033303 0.000 0.000 0.4444 0.134256 0.040545 0.000 0.000 0.5000 0.141529 0.048209 0.000 0.000 0.5556 0.148261 0.056261 0.067 0.000 0.6111 0.154522 0.064673 0.095 0.000 0.6667 0.160369 0.073422 0.117 0.000 0.7222 0.165844 0.082485 0.135 0.000 0.7778 0.170983 0.091843 0.151 0.000 0.8333 0.175816 0.101478 0.165 0.000 0.8889 0.180367 0.111373 0.178 0.000 0.9444 0.184658 0.121514 0.191 0.000 1.0000 0.188705 0.131886 0.202 0.000 1.0556 0.192525 0.142477 0.213 0.000 1.1111 0.196131 0.153274 0.224 0.000 1.1667 0.199533 0.164265 0.234 0.000 1.2222 0.202744 0.175440 0.243 0.000 1.2778 0.205770 0.186789 0.252 0.000 1.3333 0.208621 0.198300 0.261 0.000 1.3889 0.211304 0.209966 0.270 0.000 1.4444 0.213825 0.221776 0.278 0.000 1.5000 0.216189 0.233721 0.286 0.000 1.5556 0.218402 0.245794 0.294 0.000 1.6111 0.220468 0.257985 0.302 0.000 1.6667 0.222391 0.270288 0.309 0.000 1.7222 0.224176 0.282693 0.316 0.000 1.7778 0.225824 0.295194 0.324 0.000 1.8333 0.227340 0.307782 0.331 0.000 Flow control 9/11/2025 1:32:03 PM Page 12 1.8889 0.228726 0.320451 0.337 0.000 1.9444 0.229984 0.333194 0.344 0.000 2.0000 0.231116 0.346003 0.351 0.000 2.0556 0.232124 0.358871 0.357 0.000 2.1111 0.233010 0.371792 0.363 0.000 2.1667 0.233775 0.384759 0.370 0.000 2.2222 0.234421 0.397765 0.376 0.000 2.2778 0.234948 0.410803 0.382 0.000 2.3333 0.235357 0.423868 0.388 0.000 2.3889 0.235648 0.436952 0.393 0.000 2.4444 0.235823 0.450049 0.399 0.000 2.5000 0.235882 0.463152 0.405 0.000 2.5556 0.235823 0.476256 0.411 0.000 2.6111 0.235648 0.489353 0.416 0.000 2.6667 0.235357 0.502437 0.421 0.000 2.7222 0.234948 0.515501 0.427 0.000 2.7778 0.234421 0.528540 0.432 0.000 2.8333 0.233775 0.541546 0.437 0.000 2.8889 0.233010 0.554513 0.443 0.000 2.9444 0.232124 0.567434 0.448 0.000 3.0000 0.231116 0.580302 0.453 0.000 3.0556 0.229984 0.593111 0.458 0.000 3.1111 0.228726 0.605853 0.463 0.000 3.1667 0.227340 0.618523 0.468 0.000 3.2222 0.225824 0.631111 0.472 0.000 3.2778 0.224176 0.643612 0.477 0.000 3.3333 0.222391 0.656017 0.482 0.000 3.3889 0.220468 0.668319 0.487 0.000 3.4444 0.218402 0.680511 0.491 0.000 3.5000 0.216189 0.692583 0.496 0.000 3.5556 0.213825 0.704529 0.501 0.000 3.6111 0.211304 0.716339 0.505 0.000 3.6667 0.208621 0.728004 0.510 0.000 3.7222 0.205770 0.739516 0.514 0.000 3.7778 0.202744 0.750864 0.534 0.000 3.8333 0.199533 0.762039 0.603 0.000 3.8889 0.196131 0.773031 0.700 0.000 3.9444 0.192525 0.783828 0.817 0.000 4.0000 0.188705 0.794419 0.952 0.000 4.0556 0.184658 0.804791 1.102 0.000 4.1111 0.180367 0.814932 1.267 0.000 4.1667 0.175816 0.824827 1.444 0.000 4.2222 0.170983 0.834462 1.633 0.000 4.2778 0.165844 0.843819 1.833 0.000 4.3333 0.160369 0.852883 2.044 0.000 4.3889 0.154522 0.861631 2.265 0.000 4.4444 0.148261 0.870044 2.496 0.000 4.5000 0.141529 0.878096 2.736 0.000 4.5556 0.134256 0.885759 3.017 0.000 4.6111 0.126348 0.893002 3.528 0.000 4.6667 0.117678 0.899784 4.186 0.000 4.7222 0.108063 0.906060 4.957 0.000 4.7778 0.097221 0.911768 5.815 0.000 4.8333 0.084684 0.916831 6.738 0.000 4.8889 0.069540 0.921130 7.703 0.000 4.9444 0.049451 0.924469 8.684 0.000 5.0000 0.000000 0.926305 9.658 0.000 5.0556 0.000000 0.000000 10.60 0.000 Flow control 9/11/2025 1:32:03 PM Page 13 Flow control 9/11/2025 1:32:03 PM Page 14 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.31 Total Impervious Area:0.96 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.41 Total Impervious Area:0.43 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.385812 5 year 0.494566 10 year 0.569301 25 year 0.66711 50 year 0.742559 100 year 0.820316 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.191317 5 year 0.254003 10 year 0.298257 25 year 0.357415 50 year 0.403906 100 year 0.452522 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.519 0.272 1950 0.519 0.252 1951 0.323 0.169 1952 0.267 0.123 1953 0.288 0.133 1954 0.314 0.155 1955 0.352 0.170 1956 0.347 0.169 1957 0.406 0.208 1958 0.315 0.151 Peak flows are reduced from existing to proposed condition Flow control 9/11/2025 1:32:34 PM Page 15 1959 0.310 0.139 1960 0.334 0.176 1961 0.343 0.173 1962 0.287 0.134 1963 0.333 0.167 1964 0.312 0.154 1965 0.422 0.218 1966 0.270 0.131 1967 0.470 0.254 1968 0.535 0.263 1969 0.383 0.198 1970 0.360 0.178 1971 0.430 0.213 1972 0.469 0.254 1973 0.254 0.115 1974 0.399 0.203 1975 0.428 0.211 1976 0.308 0.156 1977 0.312 0.148 1978 0.385 0.184 1979 0.527 0.241 1980 0.530 0.292 1981 0.400 0.195 1982 0.578 0.302 1983 0.450 0.211 1984 0.291 0.143 1985 0.401 0.196 1986 0.339 0.170 1987 0.520 0.242 1988 0.310 0.139 1989 0.387 0.174 1990 0.769 0.446 1991 0.594 0.330 1992 0.289 0.142 1993 0.244 0.115 1994 0.258 0.116 1995 0.353 0.170 1996 0.398 0.211 1997 0.381 0.197 1998 0.365 0.172 1999 0.788 0.407 2000 0.384 0.192 2001 0.403 0.186 2002 0.510 0.269 2003 0.397 0.209 2004 0.733 0.375 2005 0.336 0.173 2006 0.301 0.158 2007 0.690 0.401 2008 0.583 0.323 2009 0.474 0.213 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.7885 0.4463 2 0.7688 0.4071 3 0.7331 0.4015 Flow control 9/11/2025 1:32:34 PM Page 16 4 0.6899 0.3747 5 0.5938 0.3297 6 0.5831 0.3234 7 0.5780 0.3024 8 0.5353 0.2915 9 0.5296 0.2718 10 0.5269 0.2694 11 0.5203 0.2633 12 0.5194 0.2541 13 0.5190 0.2537 14 0.5103 0.2519 15 0.4739 0.2417 16 0.4700 0.2410 17 0.4694 0.2184 18 0.4501 0.2130 19 0.4300 0.2130 20 0.4277 0.2114 21 0.4217 0.2113 22 0.4063 0.2111 23 0.4034 0.2095 24 0.4009 0.2079 25 0.4004 0.2027 26 0.3986 0.1980 27 0.3983 0.1968 28 0.3966 0.1965 29 0.3873 0.1950 30 0.3845 0.1920 31 0.3844 0.1859 32 0.3834 0.1840 33 0.3806 0.1783 34 0.3654 0.1760 35 0.3603 0.1735 36 0.3531 0.1729 37 0.3517 0.1728 38 0.3473 0.1725 39 0.3435 0.1703 40 0.3390 0.1700 41 0.3362 0.1699 42 0.3343 0.1689 43 0.3325 0.1686 44 0.3233 0.1674 45 0.3150 0.1583 46 0.3143 0.1565 47 0.3124 0.1554 48 0.3118 0.1536 49 0.3103 0.1507 50 0.3097 0.1483 51 0.3084 0.1433 52 0.3012 0.1421 53 0.2915 0.1392 54 0.2888 0.1388 55 0.2884 0.1343 56 0.2870 0.1326 57 0.2704 0.1307 58 0.2669 0.1225 59 0.2584 0.1158 60 0.2544 0.1153 61 0.2442 0.1149 Flow control 9/11/2025 1:32:34 PM Page 17 Flow control 9/11/2025 1:32:34 PM Page 18 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.1929 1729 121 6 Pass 0.1985 1562 108 6 Pass 0.2040 1401 101 7 Pass 0.2096 1273 94 7 Pass 0.2151 1132 79 6 Pass 0.2207 1042 73 7 Pass 0.2262 953 70 7 Pass 0.2318 882 62 7 Pass 0.2373 789 58 7 Pass 0.2429 732 52 7 Pass 0.2484 668 47 7 Pass 0.2540 627 43 6 Pass 0.2595 570 34 5 Pass 0.2651 530 32 6 Pass 0.2706 499 29 5 Pass 0.2762 451 26 5 Pass 0.2817 415 24 5 Pass 0.2873 387 22 5 Pass 0.2928 363 20 5 Pass 0.2984 344 18 5 Pass 0.3039 323 15 4 Pass 0.3095 292 15 5 Pass 0.3151 272 14 5 Pass 0.3206 254 11 4 Pass 0.3262 238 10 4 Pass 0.3317 225 8 3 Pass 0.3373 204 7 3 Pass 0.3428 194 7 3 Pass 0.3484 183 7 3 Pass 0.3539 172 7 4 Pass 0.3595 157 6 3 Pass 0.3650 148 5 3 Pass 0.3706 140 5 3 Pass 0.3761 130 3 2 Pass 0.3817 125 3 2 Pass 0.3872 114 3 2 Pass 0.3928 108 3 2 Pass 0.3983 101 3 2 Pass 0.4039 94 2 2 Pass 0.4094 88 1 1 Pass 0.4150 82 1 1 Pass 0.4205 81 1 1 Pass 0.4261 79 1 1 Pass 0.4316 76 1 1 Pass 0.4372 74 1 1 Pass 0.4427 68 1 1 Pass 0.4483 66 0 0 Pass 0.4539 63 0 0 Pass 0.4594 56 0 0 Pass 0.4650 56 0 0 Pass 0.4705 52 0 0 Pass 0.4761 47 0 0 Pass 0.4816 47 0 0 Pass Flow control 9/11/2025 1:32:34 PM Page 19 0.4872 43 0 0 Pass 0.4927 42 0 0 Pass 0.4983 40 0 0 Pass 0.5038 39 0 0 Pass 0.5094 34 0 0 Pass 0.5149 31 0 0 Pass 0.5205 28 0 0 Pass 0.5260 27 0 0 Pass 0.5316 24 0 0 Pass 0.5371 21 0 0 Pass 0.5427 20 0 0 Pass 0.5482 19 0 0 Pass 0.5538 17 0 0 Pass 0.5593 16 0 0 Pass 0.5649 15 0 0 Pass 0.5704 14 0 0 Pass 0.5760 13 0 0 Pass 0.5815 12 0 0 Pass 0.5871 9 0 0 Pass 0.5927 9 0 0 Pass 0.5982 8 0 0 Pass 0.6038 8 0 0 Pass 0.6093 8 0 0 Pass 0.6149 8 0 0 Pass 0.6204 8 0 0 Pass 0.6260 8 0 0 Pass 0.6315 8 0 0 Pass 0.6371 8 0 0 Pass 0.6426 8 0 0 Pass 0.6482 8 0 0 Pass 0.6537 7 0 0 Pass 0.6593 7 0 0 Pass 0.6648 7 0 0 Pass 0.6704 7 0 0 Pass 0.6759 7 0 0 Pass 0.6815 7 0 0 Pass 0.6870 6 0 0 Pass 0.6926 5 0 0 Pass 0.6981 5 0 0 Pass 0.7037 4 0 0 Pass 0.7092 4 0 0 Pass 0.7148 4 0 0 Pass 0.7204 4 0 0 Pass 0.7259 3 0 0 Pass 0.7315 3 0 0 Pass 0.7370 2 0 0 Pass 0.7426 2 0 0 Pass Flow control 9/11/2025 1:32:34 PM Page 20 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0 acre-feet On-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Off-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Flow control 9/11/2025 1:32:34 PM Page 21 POC 2 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #2 Total Pervious Area:10.57 Total Impervious Area:17.82 Mitigated Landuse Totals for POC #2 Total Pervious Area:6.76 Total Impervious Area:22.54 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #2 Return Period Flow(cfs) 2 year 7.479447 5 year 9.731369 10 year 11.296653 25 year 13.363718 50 year 14.97084 100 year 16.637382 Flow Frequency Return Periods for Mitigated. POC #2 Return Period Flow(cfs) 2 year 7.068426 5 year 9.081981 10 year 10.468149 25 year 12.284857 50 year 13.687967 100 year 15.135388 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #2 Year Predeveloped Mitigated 1949 10.333 9.327 1950 9.753 9.345 1951 6.423 6.049 1952 5.007 4.888 1953 5.413 5.312 1954 6.094 5.751 1955 6.748 6.408 1956 6.684 6.312 1957 8.002 7.495 1958 6.017 5.722 1959 5.762 5.544 Peak flows are reduced from existing to proposed condition Flow control 9/11/2025 1:33:02 PM Page 22 1960 6.673 6.922 1961 6.712 6.303 1962 5.429 5.248 1963 6.500 6.034 1964 6.041 5.680 1965 8.352 7.621 1966 5.190 5.039 1967 9.330 8.541 1968 10.354 9.601 1969 7.584 7.031 1970 6.987 6.621 1971 8.343 7.765 1972 9.484 8.435 1973 4.723 4.579 1974 7.829 7.118 1975 8.088 7.666 1976 6.051 5.735 1977 5.798 5.619 1978 7.337 7.048 1979 9.869 9.340 1980 10.796 9.608 1981 7.709 7.331 1982 11.399 12.230 1983 8.529 8.164 1984 5.637 5.336 1985 7.742 7.329 1986 6.510 6.386 1987 9.812 9.295 1988 5.749 5.639 1989 7.190 6.847 1990 16.081 13.946 1991 12.154 10.894 1992 5.586 5.355 1993 4.638 4.419 1994 4.797 4.628 1995 6.771 6.420 1996 7.974 7.307 1997 7.532 6.958 1998 6.939 6.604 1999 15.595 14.046 2000 7.488 6.981 2001 7.581 7.307 2002 10.198 9.484 2003 7.927 7.153 2004 14.431 13.349 2005 6.636 6.339 2006 6.006 5.642 2007 14.392 12.486 2008 11.929 12.125 2009 8.811 8.481 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #2 Rank Predeveloped Mitigated 1 16.0810 14.0461 2 15.5947 13.9458 3 14.4312 13.3494 4 14.3916 12.4856 Flow control 9/11/2025 1:33:02 PM Page 23 5 12.1542 12.2302 6 11.9291 12.1248 7 11.3992 10.8942 8 10.7955 9.6078 9 10.3537 9.6009 10 10.3333 9.4843 11 10.1978 9.3451 12 9.8693 9.3399 13 9.8118 9.3272 14 9.7531 9.2950 15 9.4844 8.5414 16 9.3301 8.4810 17 8.8107 8.4352 18 8.5291 8.1643 19 8.3523 7.7645 20 8.3433 7.6661 21 8.0880 7.6214 22 8.0023 7.4954 23 7.9738 7.3308 24 7.9274 7.3295 25 7.8290 7.3072 26 7.7422 7.3065 27 7.7090 7.1534 28 7.5836 7.1181 29 7.5813 7.0481 30 7.5318 7.0314 31 7.4875 6.9811 32 7.3367 6.9575 33 7.1899 6.9224 34 6.9874 6.8467 35 6.9388 6.6209 36 6.7706 6.6038 37 6.7479 6.4202 38 6.7123 6.4076 39 6.6844 6.3858 40 6.6729 6.3391 41 6.6365 6.3125 42 6.5104 6.3033 43 6.4997 6.0488 44 6.4225 6.0337 45 6.0943 5.7507 46 6.0506 5.7347 47 6.0409 5.7216 48 6.0171 5.6798 49 6.0056 5.6425 50 5.7977 5.6392 51 5.7624 5.6191 52 5.7490 5.5442 53 5.6367 5.3547 54 5.5858 5.3357 55 5.4294 5.3115 56 5.4131 5.2482 57 5.1905 5.0392 58 5.0068 4.8878 59 4.7973 4.6275 60 4.7235 4.5789 61 4.6382 4.4192 Flow control 9/11/2025 1:33:02 PM Page 24 Flow control 9/11/2025 1:33:02 PM Page 25 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 3.7397 1651 1662 100 Pass 3.8532 1498 1479 98 Pass 3.9666 1332 1320 99 Pass 4.0801 1195 1200 100 Pass 4.1935 1078 1069 99 Pass 4.3070 982 969 98 Pass 4.4204 893 856 95 Pass 4.5338 805 791 98 Pass 4.6473 740 717 96 Pass 4.7607 676 657 97 Pass 4.8742 627 598 95 Pass 4.9876 572 554 96 Pass 5.1011 533 512 96 Pass 5.2145 493 462 93 Pass 5.3280 448 434 96 Pass 5.4414 419 403 96 Pass 5.5549 388 373 96 Pass 5.6683 363 342 94 Pass 5.7817 338 313 92 Pass 5.8952 319 283 88 Pass 6.0086 296 270 91 Pass 6.1221 276 252 91 Pass 6.2355 253 237 93 Pass 6.3490 230 220 95 Pass 6.4624 218 209 95 Pass 6.5759 205 198 96 Pass 6.6893 191 187 97 Pass 6.8028 177 170 96 Pass 6.9162 168 161 95 Pass 7.0296 157 152 96 Pass 7.1431 148 140 94 Pass 7.2565 136 131 96 Pass 7.3700 130 120 92 Pass 7.4834 119 117 98 Pass 7.5969 108 111 102 Pass 7.7103 105 105 100 Pass 7.8238 101 100 99 Pass 7.9372 97 98 101 Pass 8.0507 88 94 106 Pass 8.1641 83 87 104 Pass 8.2775 82 76 92 Pass 8.3910 77 72 93 Pass 8.5044 76 67 88 Pass 8.6179 71 63 88 Pass 8.7313 66 60 90 Pass 8.8448 64 58 90 Pass 8.9582 61 57 93 Pass 9.0717 59 55 93 Pass 9.1851 58 54 93 Pass 9.2986 55 50 90 Pass 9.4120 50 45 90 Pass 9.5255 47 43 91 Pass 9.6389 42 40 95 Pass Flow control 9/11/2025 1:33:02 PM Page 26 9.7523 40 37 92 Pass 9.8658 37 34 91 Pass 9.9792 34 31 91 Pass 10.0927 31 30 96 Pass 10.2061 30 27 90 Pass 10.3196 30 27 90 Pass 10.4330 26 25 96 Pass 10.5465 25 23 92 Pass 10.6599 22 19 86 Pass 10.7734 22 19 86 Pass 10.8868 21 18 85 Pass 11.0002 20 17 85 Pass 11.1137 20 16 80 Pass 11.2271 17 15 88 Pass 11.3406 15 15 100 Pass 11.4540 14 11 78 Pass 11.5675 13 11 84 Pass 11.6809 13 10 76 Pass 11.7944 12 10 83 Pass 11.9078 11 10 90 Pass 12.0213 10 10 100 Pass 12.1347 9 9 100 Pass 12.2481 8 8 100 Pass 12.3616 8 8 100 Pass 12.4750 8 7 87 Pass 12.5885 8 6 75 Pass 12.7019 7 5 71 Pass 12.8154 7 5 71 Pass 12.9288 7 5 71 Pass 13.0423 7 4 57 Pass 13.1557 7 4 57 Pass 13.2692 7 3 42 Pass 13.3826 7 2 28 Pass 13.4960 7 2 28 Pass 13.6095 7 2 28 Pass 13.7229 6 2 33 Pass 13.8364 5 2 40 Pass 13.9498 5 2 40 Pass 14.0633 5 0 0 Pass 14.1767 5 0 0 Pass 14.2902 5 0 0 Pass 14.4036 3 0 0 Pass 14.5171 2 0 0 Pass 14.6305 2 0 0 Pass 14.7439 2 0 0 Pass 14.8574 2 0 0 Pass 14.9708 2 0 0 Pass Flow control 9/11/2025 1:33:02 PM Page 27 Water Quality Water Quality BMP Flow and Volume for POC #2 On-line facility volume:0 acre-feet On-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Off-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Flow control 9/11/2025 1:33:02 PM Page 28 POC 3 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #3 Total Pervious Area:2.08 Total Impervious Area:4.77 Mitigated Landuse Totals for POC #3 Total Pervious Area:1.3 Total Impervious Area:5.06 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #3 Return Period Flow(cfs) 2 year 1.951863 5 year 2.516947 10 year 2.907043 25 year 3.419417 50 year 3.815901 100 year 4.225519 Flow Frequency Return Periods for Mitigated. POC #3 Return Period Flow(cfs) 2 year 2.012219 5 year 2.571507 10 year 2.954935 25 year 3.455816 50 year 3.841558 100 year 4.23859 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #3 Year Predeveloped Mitigated 1949 2.657 2.687 1950 2.593 2.730 1951 1.654 1.675 1952 1.332 1.403 1953 1.440 1.516 1954 1.591 1.639 1955 1.772 1.838 1956 1.752 1.814 1957 2.070 2.110 1958 1.584 1.648 1959 1.542 1.635 TDA 3 is flow control exempt and is not required to match flows. Flow control 9/11/2025 1:33:31 PM Page 29 1960 1.714 1.730 1961 1.744 1.787 1962 1.437 1.506 1963 1.689 1.730 1964 1.579 1.630 1965 2.154 2.187 1966 1.363 1.414 1967 2.375 2.452 1968 2.706 2.792 1969 1.957 1.989 1970 1.824 1.878 1971 2.177 2.241 1972 2.419 2.421 1973 1.264 1.341 1974 2.029 2.071 1975 2.125 2.254 1976 1.569 1.603 1977 1.550 1.643 1978 1.933 2.018 1979 2.628 2.771 1980 2.740 2.725 1981 2.020 2.091 1982 2.939 3.005 1983 2.256 2.361 1984 1.474 1.521 1985 2.026 2.092 1986 1.699 1.778 1987 2.602 2.732 1988 1.539 1.632 1989 1.924 2.041 1990 4.023 3.927 1991 3.077 3.052 1992 1.460 1.506 1993 1.225 1.280 1994 1.284 1.362 1995 1.779 1.846 1996 2.044 2.059 1997 1.943 1.974 1998 1.833 1.915 1999 4.025 4.090 2000 1.949 2.002 2001 2.015 2.120 2002 2.617 2.640 2003 2.034 2.051 2004 3.735 3.807 2005 1.715 1.745 2006 1.543 1.559 2007 3.590 3.578 2008 3.021 2.997 2009 2.356 2.497 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #3 Rank Predeveloped Mitigated 1 4.0252 4.0896 2 4.0228 3.9266 3 3.7347 3.8067 4 3.5901 3.5780 Flow control 9/11/2025 1:33:31 PM Page 30 5 3.0774 3.0517 6 3.0212 3.0049 7 2.9393 2.9968 8 2.7397 2.7924 9 2.7064 2.7710 10 2.6572 2.7315 11 2.6280 2.7301 12 2.6170 2.7248 13 2.6024 2.6873 14 2.5934 2.6397 15 2.4188 2.4971 16 2.3748 2.4524 17 2.3564 2.4209 18 2.2561 2.3606 19 2.1770 2.2539 20 2.1542 2.2412 21 2.1255 2.1867 22 2.0705 2.1201 23 2.0440 2.1097 24 2.0341 2.0924 25 2.0288 2.0909 26 2.0257 2.0713 27 2.0204 2.0590 28 2.0150 2.0514 29 1.9574 2.0411 30 1.9495 2.0180 31 1.9434 2.0018 32 1.9329 1.9886 33 1.9244 1.9736 34 1.8329 1.9149 35 1.8237 1.8781 36 1.7787 1.8461 37 1.7720 1.8383 38 1.7524 1.8143 39 1.7444 1.7871 40 1.7149 1.7781 41 1.7135 1.7447 42 1.6989 1.7301 43 1.6890 1.7298 44 1.6535 1.6747 45 1.5909 1.6483 46 1.5841 1.6430 47 1.5793 1.6388 48 1.5689 1.6351 49 1.5505 1.6321 50 1.5430 1.6296 51 1.5420 1.6029 52 1.5387 1.5588 53 1.4736 1.5206 54 1.4601 1.5156 55 1.4395 1.5064 56 1.4374 1.5056 57 1.3628 1.4136 58 1.3319 1.4028 59 1.2841 1.3620 60 1.2641 1.3406 61 1.2253 1.2801 Flow control 9/11/2025 1:33:31 PM Page 31 Flow control 9/11/2025 1:33:31 PM Page 32 Duration Flows The Duration Matching Failed Flow(cfs)Predev Mit Percentage Pass/Fail 0.9759 1694 1938 114 Fail 1.0046 1533 1723 112 Fail 1.0333 1374 1574 114 Fail 1.0620 1235 1430 115 Fail 1.0907 1107 1280 115 Fail 1.1194 1014 1145 112 Fail 1.1481 932 1051 112 Fail 1.1767 847 961 113 Fail 1.2054 760 880 115 Fail 1.2341 704 809 114 Fail 1.2628 655 739 112 Fail 1.2915 600 677 112 Fail 1.3202 553 629 113 Fail 1.3489 518 575 111 Fail 1.3775 475 539 113 Fail 1.4062 436 502 115 Fail 1.4349 403 462 114 Fail 1.4636 375 420 112 Fail 1.4923 357 392 109 Fail 1.5210 339 366 107 Fail 1.5497 309 350 113 Fail 1.5783 287 321 111 Fail 1.6070 262 301 114 Fail 1.6357 247 276 111 Fail 1.6644 231 258 111 Fail 1.6931 214 240 112 Fail 1.7218 198 225 113 Fail 1.7505 190 207 108 Fail 1.7792 176 198 112 Fail 1.8078 165 185 112 Fail 1.8365 151 171 113 Fail 1.8652 144 160 111 Fail 1.8939 134 149 111 Fail 1.9226 129 142 110 Fail 1.9513 118 131 111 Fail 1.9800 110 124 112 Fail 2.0086 103 116 112 Fail 2.0373 97 112 115 Fail 2.0660 92 102 110 Pass 2.0947 86 96 111 Fail 2.1234 82 88 107 Pass 2.1521 79 82 103 Pass 2.1808 76 82 107 Pass 2.2095 76 79 103 Pass 2.2381 71 78 109 Pass 2.2668 66 73 110 Pass 2.2955 65 68 104 Pass 2.3242 60 64 106 Pass 2.3529 58 62 106 Pass 2.3816 53 58 109 Pass 2.4103 51 56 109 Pass 2.4389 49 52 106 Pass 2.4676 47 48 102 Pass 2.4963 42 48 114 Fail TDA 3 is flow control exempt. This calculation is included for reference only. Flow control 9/11/2025 1:33:31 PM Page 33 2.5250 41 45 109 Pass 2.5537 38 41 107 Pass 2.5824 36 40 111 Fail 2.6111 33 38 115 Fail 2.6398 29 35 120 Fail 2.6684 26 31 119 Fail 2.6971 26 29 111 Fail 2.7258 23 27 117 Fail 2.7545 21 23 109 Pass 2.7832 21 22 104 Pass 2.8119 19 20 105 Pass 2.8406 17 17 100 Pass 2.8692 17 16 94 Pass 2.8979 15 16 106 Pass 2.9266 14 15 107 Pass 2.9553 13 13 100 Pass 2.9840 12 12 100 Pass 3.0127 12 10 83 Pass 3.0414 9 9 100 Pass 3.0701 9 8 88 Pass 3.0987 8 8 100 Pass 3.1274 8 8 100 Pass 3.1561 8 8 100 Pass 3.1848 8 8 100 Pass 3.2135 8 8 100 Pass 3.2422 8 8 100 Pass 3.2709 8 8 100 Pass 3.2995 7 8 114 Fail 3.3282 7 8 114 Fail 3.3569 7 8 114 Fail 3.3856 7 7 100 Pass 3.4143 7 7 100 Pass 3.4430 7 7 100 Pass 3.4717 7 7 100 Pass 3.5003 7 6 85 Pass 3.5290 6 6 100 Pass 3.5577 6 6 100 Pass 3.5864 5 5 100 Pass 3.6151 4 5 125 Fail 3.6438 4 4 100 Pass 3.6725 4 4 100 Pass 3.7012 3 4 133 Fail 3.7298 3 4 133 Fail 3.7585 2 3 150 Fail 3.7872 2 3 150 Fail 3.8159 2 2 100 Pass The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 50% of the flows for the range of the duration analysis. Flow control 9/11/2025 1:33:31 PM Page 34 Water Quality Water Quality BMP Flow and Volume for POC #3 On-line facility volume:0 acre-feet On-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Off-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Flow control 9/11/2025 1:33:32 PM Page 35 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. Flow control 9/11/2025 1:33:32 PM Page 36 Appendix Predeveloped Schematic Flow control 9/11/2025 1:33:34 PM Page 37 Mitigated Schematic Flow control 9/11/2025 1:33:36 PM Page 38 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 Flow control.wdm MESSU 25 PreFlow control.MES 27 PreFlow control.L61 28 PreFlow control.L62 30 POCFlow control1.dat 31 POCFlow control2.dat 32 POCFlow control3.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 16 IMPLND 1 COPY 501 COPY 502 COPY 503 DISPLY 1 DISPLY 2 DISPLY 3 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 TDA 1 MAX 1 2 30 9 2 TDA 2 MAX 1 2 31 9 3 Basin 3 MAX 1 2 32 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 502 1 1 503 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 Flow control 9/11/2025 1:33:36 PM Page 39 <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 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 *** 1 ROADS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 4 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 END IWAT-PARM1 Flow control 9/11/2025 1:33:36 PM Page 40 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** TDA 1*** PERLND 16 0.31 COPY 501 12 PERLND 16 0.31 COPY 501 13 IMPLND 1 0.96 COPY 501 15 TDA 2*** PERLND 16 10.57 COPY 502 12 PERLND 16 10.57 COPY 502 13 IMPLND 1 17.82 COPY 502 15 Basin 3*** PERLND 16 2.08 COPY 503 12 PERLND 16 2.08 COPY 503 13 IMPLND 1 4.77 COPY 503 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 COPY 502 OUTPUT MEAN 1 1 48.4 DISPLY 2 INPUT TIMSER 1 COPY 503 OUTPUT MEAN 1 1 48.4 DISPLY 3 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 Flow control 9/11/2025 1:33:36 PM Page 41 HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL COPY 502 OUTPUT MEAN 1 1 48.4 WDM 502 FLOW ENGL REPL COPY 503 OUTPUT MEAN 1 1 48.4 WDM 503 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 Flow control 9/11/2025 1:33:36 PM Page 42 Mitigated UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 Flow control.wdm MESSU 25 MitFlow control.MES 27 MitFlow control.L61 28 MitFlow control.L62 30 POCFlow control1.dat 32 POCFlow control3.dat 31 POCFlow control2.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 16 IMPLND 1 RCHRES 1 COPY 501 COPY 503 COPY 2 COPY 502 COPY 602 DISPLY 1 DISPLY 3 DISPLY 2 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 3 Basin 3 MAX 1 2 32 9 2 Tank 2B MAX 1 2 31 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 503 1 1 2 1 1 502 1 1 602 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 *** Flow control 9/11/2025 1:33:36 PM Page 43 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 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 *** 1 ROADS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 4 1 9 END PRINT-INFO IWAT-PARM1 Flow control 9/11/2025 1:33:36 PM Page 44 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 2B*** PERLND 16 0.94 RCHRES 1 2 PERLND 16 0.94 RCHRES 1 3 IMPLND 1 5.91 RCHRES 1 5 Basin 1*** PERLND 16 0.41 COPY 501 12 PERLND 16 0.41 COPY 501 13 IMPLND 1 0.43 COPY 501 15 Basin 2A*** PERLND 16 5.82 COPY 502 12 PERLND 16 5.82 COPY 602 12 PERLND 16 5.82 COPY 502 13 PERLND 16 5.82 COPY 602 13 IMPLND 1 16.63 COPY 502 15 IMPLND 1 16.63 COPY 602 15 Basin 3*** PERLND 16 1.3 COPY 503 12 PERLND 16 1.3 COPY 503 13 IMPLND 1 5.06 COPY 503 15 ******Routing****** PERLND 16 0.94 COPY 2 12 IMPLND 1 5.91 COPY 2 15 PERLND 16 0.94 COPY 2 13 RCHRES 1 1 COPY 502 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 COPY 503 OUTPUT MEAN 1 1 48.4 DISPLY 3 INPUT TIMSER 1 COPY 502 OUTPUT MEAN 1 1 48.4 DISPLY 2 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO Flow control 9/11/2025 1:33:36 PM Page 45 RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** 1 Tank 2B 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 *** <------><--------><--------><--------><--------><--------><--------> *** 1 1 0.39 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 0.055556 0.049451 0.001836 0.000000 0.111111 0.069540 0.005174 0.000000 0.166667 0.084684 0.009474 0.000000 0.222222 0.097221 0.014536 0.000000 0.277778 0.108063 0.020245 0.000000 0.333333 0.117678 0.026521 0.000000 0.388889 0.126348 0.033303 0.000000 0.444444 0.134256 0.040545 0.000000 0.500000 0.141529 0.048209 0.000000 0.555556 0.148261 0.056261 0.067560 0.611111 0.154522 0.064673 0.095544 0.666667 0.160369 0.073422 0.117017 0.722222 0.165844 0.082485 0.135120 0.777778 0.170983 0.091843 0.151069 0.833333 0.175816 0.101478 0.165487 0.888889 0.180367 0.111373 0.178747 0.944444 0.184658 0.121514 0.191088 1.000000 0.188705 0.131886 0.202680 1.055556 0.192525 0.142477 0.213643 1.111111 0.196131 0.153274 0.224071 1.166667 0.199533 0.164265 0.234034 Flow control 9/11/2025 1:33:36 PM Page 46 1.222222 0.202744 0.175440 0.243591 1.277778 0.205770 0.186789 0.252786 1.333333 0.208621 0.198300 0.261658 1.388889 0.211304 0.209966 0.270240 1.444444 0.213825 0.221776 0.278557 1.500000 0.216189 0.233721 0.286633 1.555556 0.218402 0.245794 0.294487 1.611111 0.220468 0.257985 0.302137 1.666667 0.222391 0.270288 0.309598 1.722222 0.224176 0.282693 0.316884 1.777778 0.225824 0.295194 0.324006 1.833333 0.227340 0.307782 0.330975 1.888889 0.228726 0.320451 0.337800 1.944444 0.229984 0.333194 0.344489 2.000000 0.231116 0.346003 0.351052 2.055556 0.232124 0.358871 0.357494 2.111111 0.233010 0.371792 0.363821 2.166667 0.233775 0.384759 0.370041 2.222222 0.234421 0.397765 0.376158 2.277778 0.234948 0.410803 0.382177 2.333333 0.235357 0.423868 0.388102 2.388889 0.235648 0.436952 0.393939 2.444444 0.235823 0.450049 0.399690 2.500000 0.235882 0.463152 0.405360 2.555556 0.235823 0.476256 0.410951 2.611111 0.235648 0.489353 0.416467 2.666667 0.235357 0.502437 0.421912 2.722222 0.234948 0.515501 0.427287 2.777778 0.234421 0.528540 0.432595 2.833333 0.233775 0.541546 0.437838 2.888889 0.233010 0.554513 0.443020 2.944444 0.232124 0.567434 0.448142 3.000000 0.231116 0.580302 0.453206 3.055556 0.229984 0.593111 0.458214 3.111111 0.228726 0.605853 0.463168 3.166667 0.227340 0.618523 0.468069 3.222222 0.225824 0.631111 0.472920 3.277778 0.224176 0.643612 0.477721 3.333333 0.222391 0.656017 0.482474 3.388889 0.220468 0.668319 0.487182 3.444444 0.218402 0.680511 0.491844 3.500000 0.216189 0.692583 0.496462 3.555556 0.213825 0.704529 0.501038 3.611111 0.211304 0.716339 0.505572 3.666667 0.208621 0.728004 0.510066 3.722222 0.205770 0.739516 0.514521 3.777778 0.202744 0.750864 0.534354 3.833333 0.199533 0.762039 0.603424 3.888889 0.196131 0.773031 0.700023 3.944444 0.192525 0.783828 0.817488 4.000000 0.188705 0.794419 0.952490 4.055556 0.184658 0.804791 1.102924 4.111111 0.180367 0.814932 1.267298 4.166667 0.175816 0.824827 1.444487 4.222222 0.170983 0.834462 1.633599 4.277778 0.165844 0.843819 1.833908 4.333333 0.160369 0.852883 2.044804 4.388889 0.154522 0.861631 2.265769 4.444444 0.148261 0.870044 2.496353 4.500000 0.141529 0.878096 2.736163 4.555556 0.134256 0.885759 3.017927 4.611111 0.126348 0.893002 3.528840 4.666667 0.117678 0.899784 4.186476 4.722222 0.108063 0.906060 4.957134 4.777778 0.097221 0.911768 5.815663 4.833333 0.084684 0.916831 6.738783 4.888889 0.069540 0.921130 7.703052 4.944444 0.049451 0.924469 8.684411 5.000000 0.001000 0.926305 9.658470 END FTABLE 1 Flow control 9/11/2025 1:33:36 PM Page 47 END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL COPY 601 OUTPUT MEAN 1 1 48.4 WDM 901 FLOW ENGL REPL COPY 2 OUTPUT MEAN 1 1 48.4 WDM 702 FLOW ENGL REPL COPY 502 OUTPUT MEAN 1 1 48.4 WDM 802 FLOW ENGL REPL COPY 602 OUTPUT MEAN 1 1 48.4 WDM 902 FLOW ENGL REPL RCHRES 1 HYDR RO 1 1 1 WDM 1000 FLOW ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1001 STAG ENGL REPL COPY 3 OUTPUT MEAN 1 1 48.4 WDM 703 FLOW ENGL REPL COPY 503 OUTPUT MEAN 1 1 48.4 WDM 803 FLOW ENGL REPL COPY 603 OUTPUT MEAN 1 1 48.4 WDM 903 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 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 Flow control 9/11/2025 1:33:36 PM Page 48 Predeveloped HSPF Message File Flow control 9/11/2025 1:33:36 PM Page 49 Mitigated HSPF Message File Flow control 9/11/2025 1:33:36 PM Page 50 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2025; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com Technical Information Report New Renton High School Project No. 2230388.10 Appendix D Water Quality Calculations WWHM2012 PROJECT REPORT APPENDIX D WATER QUALITY CALCULATIONS Treatment 9/9/2025 3:43:27 PM Page 2 General Model Information WWHM2012 Project Name:Treatment Site Name: Site Address: City: Report Date:9/9/2025 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2025/05/13 Version:4.3.2 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year Low Flow Threshold for POC2:50 Percent of the 2 Year High Flow Threshold for POC2:50 Year Low Flow Threshold for POC5:50 Percent of the 2 Year High Flow Threshold for POC5:50 Year Low Flow Threshold for POC6:50 Percent of the 2 Year High Flow Threshold for POC6:50 Year Low Flow Threshold for POC7:50 Percent of the 2 Year High Flow Threshold for POC7:50 Year Low Flow Threshold for POC8:50 Percent of the 2 Year High Flow Threshold for POC8:50 Year Low Flow Threshold for POC9:50 Percent of the 2 Year High Flow Threshold for POC9:50 Year Low Flow Threshold for POC10:50 Percent of the 2 Year High Flow Threshold for POC10:50 Year Low Flow Threshold for POC11:50 Percent of the 2 Year High Flow Threshold for POC11:50 Year Treatment 9/9/2025 3:43:27 PM Page 3 Low Flow Threshold for POC12:50 Percent of the 2 Year High Flow Threshold for POC12:50 Year Low Flow Threshold for POC13:50 Percent of the 2 Year High Flow Threshold for POC13:50 Year Treatment 9/9/2025 3:43:27 PM Page 4 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.45 Pervious Total 0.45 Impervious Land Use acre ROADS FLAT 0.95 Impervious Total 0.95 Basin Total 1.4 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 1 POC 1 Treatment 9/9/2025 3:43:27 PM Page 5 Basin 5 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.27 Pervious Total 0.27 Impervious Land Use acre ROADS FLAT 1.86 Impervious Total 1.86 Basin Total 2.13 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 5 POC 5 Treatment 9/9/2025 3:43:27 PM Page 6 Basin 6 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.11 Pervious Total 0.11 Impervious Land Use acre ROADS FLAT 0.98 Impervious Total 0.98 Basin Total 1.09 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 6 POC 6 Treatment 9/9/2025 3:43:27 PM Page 7 Basin 7 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.04 Pervious Total 0.04 Impervious Land Use acre ROADS FLAT 3.73 Impervious Total 3.73 Basin Total 3.77 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 7 POC 7 Treatment 9/9/2025 3:43:27 PM Page 8 Basin 8 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 1.57 Pervious Total 1.57 Impervious Land Use acre ROADS FLAT 6.93 Impervious Total 6.93 Basin Total 8.5 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 8 POC 8 Treatment 9/9/2025 3:43:27 PM Page 9 Basin 9 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 2.72 Impervious Total 2.72 Basin Total 2.72 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 9 POC 9 Treatment 9/9/2025 3:43:27 PM Page 10 Basin 10 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.1 Pervious Total 0.1 Impervious Land Use acre ROADS FLAT 0.11 Impervious Total 0.11 Basin Total 0.21 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 10 POC 10 Treatment 9/9/2025 3:43:27 PM Page 11 Basin 11 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.24 Pervious Total 0.24 Impervious Land Use acre ROADS FLAT 0.58 Impervious Total 0.58 Basin Total 0.82 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 11 POC 11 Treatment 9/9/2025 3:43:27 PM Page 12 Basin 12 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.27 Pervious Total 0.27 Impervious Land Use acre ROADS FLAT 0.51 Impervious Total 0.51 Basin Total 0.78 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 12 POC 12 Treatment 9/9/2025 3:43:27 PM Page 13 Basin 13 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.06 Pervious Total 0.06 Impervious Land Use acre ROADS FLAT 0.4 Impervious Total 0.4 Basin Total 0.46 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 13 POC 13 Treatment 9/9/2025 3:43:27 PM Page 14 Basin 2 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 1.91 Impervious Total 1.91 Basin Total 1.91 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 2 POC 2 Treatment 9/9/2025 3:43:27 PM Page 15 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.45 Pervious Total 0.45 Impervious Land Use acre ROADS FLAT 0.95 Impervious Total 0.95 Basin Total 1.4 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 1 POC 1 Treatment 9/9/2025 3:43:27 PM Page 16 Basin 5 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.27 Pervious Total 0.27 Impervious Land Use acre ROADS FLAT 1.86 Impervious Total 1.86 Basin Total 2.13 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 5 POC 5 Treatment 9/9/2025 3:43:27 PM Page 17 Basin 6 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.11 Pervious Total 0.11 Impervious Land Use acre ROADS FLAT 0.98 Impervious Total 0.98 Basin Total 1.09 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 6 POC 6 Treatment 9/9/2025 3:43:27 PM Page 18 Basin 7 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.04 Pervious Total 0.04 Impervious Land Use acre ROADS FLAT 3.73 Impervious Total 3.73 Basin Total 3.77 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 7 POC 7 Treatment 9/9/2025 3:43:27 PM Page 19 Basin 8 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 1.57 Pervious Total 1.57 Impervious Land Use acre ROADS FLAT 6.93 Impervious Total 6.93 Basin Total 8.5 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 8 POC 8 Treatment 9/9/2025 3:43:27 PM Page 20 Basin 9 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 2.72 Impervious Total 2.72 Basin Total 2.72 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 9 POC 9 Treatment 9/9/2025 3:43:27 PM Page 21 Basin 10 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.1 Pervious Total 0.1 Impervious Land Use acre ROADS FLAT 0.11 Impervious Total 0.11 Basin Total 0.21 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 10 POC 10 Treatment 9/9/2025 3:43:27 PM Page 22 Basin 11 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.24 Pervious Total 0.24 Impervious Land Use acre ROADS FLAT 0.58 Impervious Total 0.58 Basin Total 0.82 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 11 POC 11 Treatment 9/9/2025 3:43:27 PM Page 23 Basin 12 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.27 Pervious Total 0.27 Impervious Land Use acre ROADS FLAT 0.51 Impervious Total 0.51 Basin Total 0.78 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 12 POC 12 Treatment 9/9/2025 3:43:27 PM Page 24 Basin 13 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.06 Pervious Total 0.06 Impervious Land Use acre ROADS FLAT 0.4 Impervious Total 0.4 Basin Total 0.46 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 13 POC 13 Treatment 9/9/2025 3:43:27 PM Page 25 Basin 2 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 1.91 Impervious Total 1.91 Basin Total 1.91 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 2 POC 2 Treatment 9/9/2025 3:43:27 PM Page 26 Routing Elements Predeveloped Routing Treatment 9/9/2025 3:43:27 PM Page 27 Mitigated Routing Treatment 9/9/2025 3:43:27 PM Page 28 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.45 Total Impervious Area:0.95 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.45 Total Impervious Area:0.95 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.39105 5 year 0.505309 10 year 0.584312 25 year 0.688208 50 year 0.768693 100 year 0.851916 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.39105 5 year 0.505309 10 year 0.584312 25 year 0.688208 50 year 0.768693 100 year 0.851916 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.534 0.534 1950 0.517 0.517 1951 0.332 0.332 1952 0.266 0.266 1953 0.287 0.287 1954 0.319 0.319 1955 0.355 0.355 1956 0.351 0.351 1957 0.416 0.416 1958 0.317 0.317 This calculation is for water quality only. Irrelevant pages from the WWHM report have been deleted. Treatment 9/9/2025 3:44:03 PM Page 34 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0.1307 acre-feet On-line facility target flow:0.152 cfs. Adjusted for 15 min:0.152 cfs. Off-line facility target flow:0.0852 cfs. Adjusted for 15 min:0.0852 cfs. Design flowrate Treatment 9/9/2025 3:44:03 PM Page 35 POC 2 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #2 Total Pervious Area:0 Total Impervious Area:1.91 Mitigated Landuse Totals for POC #2 Total Pervious Area:0 Total Impervious Area:1.91 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #2 Return Period Flow(cfs) 2 year 0.728215 5 year 0.919821 10 year 1.050003 25 year 1.218869 50 year 1.348114 100 year 1.480498 Flow Frequency Return Periods for Mitigated. POC #2 Return Period Flow(cfs) 2 year 0.728215 5 year 0.919821 10 year 1.050003 25 year 1.218869 50 year 1.348114 100 year 1.480498 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #2 Year Predeveloped Mitigated 1949 0.943 0.943 1950 1.019 1.019 1951 0.589 0.589 1952 0.524 0.524 1953 0.566 0.566 1954 0.592 0.592 1955 0.671 0.671 1956 0.661 0.661 1957 0.749 0.749 1958 0.605 0.605 1959 0.617 0.617 This calculation is for water quality only. Irrelevant pages from the WWHM report have been deleted. Treatment 9/9/2025 3:44:35 PM Page 41 Water Quality Water Quality BMP Flow and Volume for POC #2 On-line facility volume:0.2349 acre-feet On-line facility target flow:0.3103 cfs. Adjusted for 15 min:0.3103 cfs. Off-line facility target flow:0.1753 cfs. Adjusted for 15 min:0.1753 cfs. Design flowrate Treatment 9/9/2025 3:44:35 PM Page 44 POC 5 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #5 Total Pervious Area:0.27 Total Impervious Area:1.86 Mitigated Landuse Totals for POC #5 Total Pervious Area:0.27 Total Impervious Area:1.86 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #5 Return Period Flow(cfs) 2 year 0.726467 5 year 0.923569 10 year 1.058155 25 year 1.233417 50 year 1.368019 100 year 1.506261 Flow Frequency Return Periods for Mitigated. POC #5 Return Period Flow(cfs) 2 year 0.726467 5 year 0.923569 10 year 1.058155 25 year 1.233417 50 year 1.368019 100 year 1.506261 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #5 Year Predeveloped Mitigated 1949 0.958 0.958 1950 0.999 0.999 1951 0.597 0.597 1952 0.513 0.513 1953 0.555 0.555 1954 0.591 0.591 1955 0.666 0.666 1956 0.657 0.657 1957 0.756 0.756 1958 0.599 0.599 1959 0.601 0.601 This calculation is for water quality only. Irrelevant pages from the WWHM report have been deleted. Treatment 9/9/2025 3:45:10 PM Page 50 Water Quality Water Quality BMP Flow and Volume for POC #5 On-line facility volume:0.2371 acre-feet On-line facility target flow:0.2994 cfs. Adjusted for 15 min:0.2994 cfs. Off-line facility target flow:0.1691 cfs. Adjusted for 15 min:0.1691 cfs. Design flowrate Treatment 9/9/2025 3:45:10 PM Page 51 POC 6 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #6 Total Pervious Area:0.11 Total Impervious Area:0.98 Mitigated Landuse Totals for POC #6 Total Pervious Area:0.11 Total Impervious Area:0.98 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #6 Return Period Flow(cfs) 2 year 0.380706 5 year 0.483269 10 year 0.553221 25 year 0.64423 50 year 0.714071 100 year 0.785755 Flow Frequency Return Periods for Mitigated. POC #6 Return Period Flow(cfs) 2 year 0.380706 5 year 0.483269 10 year 0.553221 25 year 0.64423 50 year 0.714071 100 year 0.785755 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #6 Year Predeveloped Mitigated 1949 0.500 0.500 1950 0.525 0.525 1951 0.312 0.312 1952 0.270 0.270 1953 0.292 0.292 1954 0.310 0.310 1955 0.350 0.350 1956 0.344 0.344 1957 0.395 0.395 1958 0.314 0.314 1959 0.317 0.317 This calculation is for water quality only. Irrelevant pages from the WWHM report have been deleted. Treatment 9/9/2025 3:45:46 PM Page 57 Water Quality Water Quality BMP Flow and Volume for POC #6 On-line facility volume:0.1241 acre-feet On-line facility target flow:0.1579 cfs. Adjusted for 15 min:0.1579 cfs. Off-line facility target flow:0.0893 cfs. Adjusted for 15 min:0.0893 cfs. Design flowrate Treatment 9/9/2025 3:45:46 PM Page 58 POC 7 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #7 Total Pervious Area:0.04 Total Impervious Area:3.73 Mitigated Landuse Totals for POC #7 Total Pervious Area:0.04 Total Impervious Area:3.73 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #7 Return Period Flow(cfs) 2 year 1.424702 5 year 1.800394 10 year 2.055742 25 year 2.387057 50 year 2.640699 100 year 2.900551 Flow Frequency Return Periods for Mitigated. POC #7 Return Period Flow(cfs) 2 year 1.424702 5 year 1.800394 10 year 2.055742 25 year 2.387057 50 year 2.640699 100 year 2.900551 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #7 Year Predeveloped Mitigated 1949 1.848 1.848 1950 1.991 1.991 1951 1.154 1.154 1952 1.024 1.024 1953 1.106 1.106 1954 1.159 1.159 1955 1.313 1.313 1956 1.292 1.292 1957 1.467 1.467 1958 1.183 1.183 1959 1.205 1.205 This calculation is for water quality only. Irrelevant pages from the WWHM report have been deleted. Treatment 9/9/2025 3:46:20 PM Page 64 Water Quality Water Quality BMP Flow and Volume for POC #7 On-line facility volume:0.4594 acre-feet On-line facility target flow:0.6056 cfs. Adjusted for 15 min:0.6056 cfs. Off-line facility target flow:0.3421 cfs. Adjusted for 15 min:0.3421 cfs. Design flowrate Treatment 9/9/2025 3:46:20 PM Page 65 POC 8 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #8 Total Pervious Area:1.57 Total Impervious Area:6.93 Mitigated Landuse Totals for POC #8 Total Pervious Area:1.57 Total Impervious Area:6.93 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #8 Return Period Flow(cfs) 2 year 2.742423 5 year 3.49977 10 year 4.018421 25 year 4.695376 50 year 5.216331 100 year 5.752221 Flow Frequency Return Periods for Mitigated. POC #8 Return Period Flow(cfs) 2 year 2.742423 5 year 3.49977 10 year 4.018421 25 year 4.695376 50 year 5.216331 100 year 5.752221 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #8 Year Predeveloped Mitigated 1949 3.650 3.650 1950 3.734 3.734 1951 2.275 2.275 1952 1.919 1.919 1953 2.073 2.073 1954 2.233 2.233 1955 2.508 2.508 1956 2.474 2.474 1957 2.869 2.869 1958 2.250 2.250 1959 2.239 2.239 This calculation is for water quality only. Irrelevant pages from the WWHM report have been deleted. Treatment 9/9/2025 3:46:53 PM Page 71 Water Quality Water Quality BMP Flow and Volume for POC #8 On-line facility volume:0.9006 acre-feet On-line facility target flow:1.1147 cfs. Adjusted for 15 min:1.1147 cfs. Off-line facility target flow:0.6278 cfs. Adjusted for 15 min:0.6278 cfs. Design flowrate Treatment 9/9/2025 3:46:53 PM Page 72 POC 9 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #9 Total Pervious Area:0 Total Impervious Area:2.72 Mitigated Landuse Totals for POC #9 Total Pervious Area:0 Total Impervious Area:2.72 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #9 Return Period Flow(cfs) 2 year 1.03704 5 year 1.309901 10 year 1.495292 25 year 1.73577 50 year 1.919826 100 year 2.108352 Flow Frequency Return Periods for Mitigated. POC #9 Return Period Flow(cfs) 2 year 1.03704 5 year 1.309901 10 year 1.495292 25 year 1.73577 50 year 1.919826 100 year 2.108352 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #9 Year Predeveloped Mitigated 1949 1.343 1.343 1950 1.451 1.451 1951 0.839 0.839 1952 0.746 0.746 1953 0.806 0.806 1954 0.843 0.843 1955 0.956 0.956 1956 0.941 0.941 1957 1.067 1.067 1958 0.861 0.861 1959 0.878 0.878 This calculation is for water quality only. Irrelevant pages from the WWHM report have been deleted. Treatment 9/9/2025 3:47:24 PM Page 78 Water Quality Water Quality BMP Flow and Volume for POC #9 On-line facility volume:0.3345 acre-feet On-line facility target flow:0.4418 cfs. Adjusted for 15 min:0.4418 cfs. Off-line facility target flow:0.2497 cfs. Adjusted for 15 min:0.2497 cfs. Design flowrate Treatment 9/9/2025 3:47:24 PM Page 79 POC 10 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #10 Total Pervious Area:0.1 Total Impervious Area:0.11 Mitigated Landuse Totals for POC #10 Total Pervious Area:0.1 Total Impervious Area:0.11 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #10 Return Period Flow(cfs) 2 year 0.048594 5 year 0.06436 10 year 0.07547 25 year 0.090301 50 year 0.10194 100 year 0.1141 Flow Frequency Return Periods for Mitigated. POC #10 Return Period Flow(cfs) 2 year 0.048594 5 year 0.06436 10 year 0.07547 25 year 0.090301 50 year 0.10194 100 year 0.1141 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #10 Year Predeveloped Mitigated 1949 0.069 0.069 1950 0.064 0.064 1951 0.043 0.043 1952 0.031 0.031 1953 0.034 0.034 1954 0.039 0.039 1955 0.043 0.043 1956 0.043 0.043 1957 0.053 0.053 1958 0.038 0.038 1959 0.036 0.036 This calculation is for water quality only. Irrelevant pages from the WWHM report have been deleted. Treatment 9/9/2025 3:47:59 PM Page 85 Water Quality Water Quality BMP Flow and Volume for POC #10 On-line facility volume:0.0165 acre-feet On-line facility target flow:0.0176 cfs. Adjusted for 15 min:0.0176 cfs. Off-line facility target flow:0.0098 cfs. Adjusted for 15 min:0.0098 cfs. Design flowrate Treatment 9/9/2025 3:47:59 PM Page 86 POC 11 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #11 Total Pervious Area:0.24 Total Impervious Area:0.58 Mitigated Landuse Totals for POC #11 Total Pervious Area:0.24 Total Impervious Area:0.58 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #11 Return Period Flow(cfs) 2 year 0.236498 5 year 0.304595 10 year 0.351561 25 year 0.413203 50 year 0.460872 100 year 0.510096 Flow Frequency Return Periods for Mitigated. POC #11 Return Period Flow(cfs) 2 year 0.236498 5 year 0.304595 10 year 0.351561 25 year 0.413203 50 year 0.460872 100 year 0.510096 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #11 Year Predeveloped Mitigated 1949 0.321 0.321 1950 0.315 0.315 1951 0.200 0.200 1952 0.162 0.162 1953 0.175 0.175 1954 0.193 0.193 1955 0.215 0.215 1956 0.212 0.212 1957 0.251 0.251 1958 0.192 0.192 1959 0.187 0.187 This calculation is for water quality only. Irrelevant pages from the WWHM report have been deleted. Treatment 9/9/2025 3:48:33 PM Page 92 Water Quality Water Quality BMP Flow and Volume for POC #11 On-line facility volume:0.0788 acre-feet On-line facility target flow:0.0927 cfs. Adjusted for 15 min:0.0927 cfs. Off-line facility target flow:0.0521 cfs. Adjusted for 15 min:0.0521 cfs. Design flowrate Treatment 9/9/2025 3:48:33 PM Page 93 POC 12 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #12 Total Pervious Area:0.27 Total Impervious Area:0.51 Mitigated Landuse Totals for POC #12 Total Pervious Area:0.27 Total Impervious Area:0.51 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #12 Return Period Flow(cfs) 2 year 0.211829 5 year 0.274591 10 year 0.318093 25 year 0.375412 50 year 0.419889 100 year 0.465941 Flow Frequency Return Periods for Mitigated. POC #12 Return Period Flow(cfs) 2 year 0.211829 5 year 0.274591 10 year 0.318093 25 year 0.375412 50 year 0.419889 100 year 0.465941 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #12 Year Predeveloped Mitigated 1949 0.291 0.291 1950 0.278 0.278 1951 0.181 0.181 1952 0.143 0.143 1953 0.155 0.155 1954 0.173 0.173 1955 0.192 0.192 1956 0.190 0.190 1957 0.226 0.226 1958 0.171 0.171 1959 0.165 0.165 This calculation is for water quality only. Irrelevant pages from the WWHM report have been deleted. Treatment 9/9/2025 3:49:08 PM Page 99 Water Quality Water Quality BMP Flow and Volume for POC #12 On-line facility volume:0.071 acre-feet On-line facility target flow:0.0814 cfs. Adjusted for 15 min:0.0814 cfs. Off-line facility target flow:0.0457 cfs. Adjusted for 15 min:0.0457 cfs. Design flowrate Treatment 9/9/2025 3:49:08 PM Page 100 POC 13 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #13 Total Pervious Area:0.06 Total Impervious Area:0.4 Mitigated Landuse Totals for POC #13 Total Pervious Area:0.06 Total Impervious Area:0.4 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #13 Return Period Flow(cfs) 2 year 0.156353 5 year 0.198818 10 year 0.227819 25 year 0.265591 50 year 0.294603 100 year 0.324402 Flow Frequency Return Periods for Mitigated. POC #13 Return Period Flow(cfs) 2 year 0.156353 5 year 0.198818 10 year 0.227819 25 year 0.265591 50 year 0.294603 100 year 0.324402 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #13 Year Predeveloped Mitigated 1949 0.206 0.206 1950 0.215 0.215 1951 0.129 0.129 1952 0.110 0.110 1953 0.119 0.119 1954 0.127 0.127 1955 0.143 0.143 1956 0.141 0.141 1957 0.163 0.163 1958 0.129 0.129 1959 0.129 0.129 This calculation is for water quality only. Irrelevant pages from the WWHM report have been deleted. Treatment 9/9/2025 3:49:42 PM Page 106 Water Quality Water Quality BMP Flow and Volume for POC #13 On-line facility volume:0.051 acre-feet On-line facility target flow:0.0644 cfs. Adjusted for 15 min:0.0644 cfs. Off-line facility target flow:0.0363 cfs. Adjusted for 15 min:0.0363 cfs. Design flowrate Treatment 9/9/2025 3:49:42 PM Page 107 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. Treatment 9/9/2025 3:49:43 PM Page 108 Appendix Predeveloped Schematic Treatment 9/9/2025 3:49:43 PM Page 109 Mitigated Schematic Treatment 9/9/2025 3:49:44 PM Page 110 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 Treatment.wdm MESSU 25 PreTreatment.MES 27 PreTreatment.L61 28 PreTreatment.L62 30 POCTreatment1.dat 34 POCTreatment5.dat 35 POCTreatment6.dat 36 POCTreatment7.dat 37 POCTreatment8.dat 38 POCTreatment9.dat 39 POCTreatment10.dat 40 POCTreatment11.dat 41 POCTreatment12.dat 42 POCTreatment13.dat 31 POCTreatment2.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 16 IMPLND 1 COPY 501 COPY 505 COPY 506 COPY 507 COPY 508 COPY 509 COPY 510 COPY 511 COPY 512 COPY 513 COPY 502 DISPLY 1 DISPLY 5 DISPLY 6 DISPLY 7 DISPLY 8 DISPLY 9 DISPLY 10 DISPLY 11 DISPLY 12 DISPLY 13 DISPLY 2 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 5 Basin 5 MAX 1 2 34 9 6 Basin 6 MAX 1 2 35 9 7 Basin 7 MAX 1 2 36 9 8 Basin 8 MAX 1 2 37 9 9 Basin 9 MAX 1 2 38 9 10 Basin 10 MAX 1 2 39 9 11 Basin 11 MAX 1 2 40 9 Treatment 9/9/2025 3:49:44 PM Page 111 12 Basin 12 MAX 1 2 41 9 13 Basin 13 MAX 1 2 42 9 2 Basin 2 MAX 1 2 31 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 505 1 1 506 1 1 507 1 1 508 1 1 509 1 1 510 1 1 511 1 1 512 1 1 513 1 1 502 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 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 *** Treatment 9/9/2025 3:49:44 PM Page 112 # - # 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 *** 1 ROADS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 4 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 16 0.45 COPY 501 12 PERLND 16 0.45 COPY 501 13 IMPLND 1 0.95 COPY 501 15 Basin 5*** PERLND 16 0.27 COPY 505 12 PERLND 16 0.27 COPY 505 13 Treatment 9/9/2025 3:49:44 PM Page 113 IMPLND 1 1.86 COPY 505 15 Basin 6*** PERLND 16 0.11 COPY 506 12 PERLND 16 0.11 COPY 506 13 IMPLND 1 0.98 COPY 506 15 Basin 7*** PERLND 16 0.04 COPY 507 12 PERLND 16 0.04 COPY 507 13 IMPLND 1 3.73 COPY 507 15 Basin 8*** PERLND 16 1.57 COPY 508 12 PERLND 16 1.57 COPY 508 13 IMPLND 1 6.93 COPY 508 15 Basin 9*** IMPLND 1 2.72 COPY 509 15 Basin 10*** PERLND 16 0.1 COPY 510 12 PERLND 16 0.1 COPY 510 13 IMPLND 1 0.11 COPY 510 15 Basin 11*** PERLND 16 0.24 COPY 511 12 PERLND 16 0.24 COPY 511 13 IMPLND 1 0.58 COPY 511 15 Basin 12*** PERLND 16 0.27 COPY 512 12 PERLND 16 0.27 COPY 512 13 IMPLND 1 0.51 COPY 512 15 Basin 13*** PERLND 16 0.06 COPY 513 12 PERLND 16 0.06 COPY 513 13 IMPLND 1 0.4 COPY 513 15 Basin 2*** IMPLND 1 1.91 COPY 502 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 COPY 505 OUTPUT MEAN 1 1 48.4 DISPLY 5 INPUT TIMSER 1 COPY 506 OUTPUT MEAN 1 1 48.4 DISPLY 6 INPUT TIMSER 1 COPY 507 OUTPUT MEAN 1 1 48.4 DISPLY 7 INPUT TIMSER 1 COPY 508 OUTPUT MEAN 1 1 48.4 DISPLY 8 INPUT TIMSER 1 COPY 509 OUTPUT MEAN 1 1 48.4 DISPLY 9 INPUT TIMSER 1 COPY 510 OUTPUT MEAN 1 1 48.4 DISPLY 10 INPUT TIMSER 1 COPY 511 OUTPUT MEAN 1 1 48.4 DISPLY 11 INPUT TIMSER 1 COPY 512 OUTPUT MEAN 1 1 48.4 DISPLY 12 INPUT TIMSER 1 COPY 513 OUTPUT MEAN 1 1 48.4 DISPLY 13 INPUT TIMSER 1 COPY 502 OUTPUT MEAN 1 1 48.4 DISPLY 2 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 Treatment 9/9/2025 3:49:44 PM Page 114 PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL COPY 505 OUTPUT MEAN 1 1 48.4 WDM 505 FLOW ENGL REPL COPY 506 OUTPUT MEAN 1 1 48.4 WDM 506 FLOW ENGL REPL COPY 507 OUTPUT MEAN 1 1 48.4 WDM 507 FLOW ENGL REPL COPY 508 OUTPUT MEAN 1 1 48.4 WDM 508 FLOW ENGL REPL COPY 509 OUTPUT MEAN 1 1 48.4 WDM 509 FLOW ENGL REPL COPY 510 OUTPUT MEAN 1 1 48.4 WDM 510 FLOW ENGL REPL COPY 511 OUTPUT MEAN 1 1 48.4 WDM 511 FLOW ENGL REPL COPY 512 OUTPUT MEAN 1 1 48.4 WDM 512 FLOW ENGL REPL COPY 513 OUTPUT MEAN 1 1 48.4 WDM 513 FLOW ENGL REPL COPY 502 OUTPUT MEAN 1 1 48.4 WDM 502 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 Treatment 9/9/2025 3:49:44 PM Page 115 END MASS-LINK END RUN Treatment 9/9/2025 3:49:44 PM Page 116 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 Treatment.wdm MESSU 25 MitTreatment.MES 27 MitTreatment.L61 28 MitTreatment.L62 30 POCTreatment1.dat 34 POCTreatment5.dat 35 POCTreatment6.dat 36 POCTreatment7.dat 37 POCTreatment8.dat 38 POCTreatment9.dat 39 POCTreatment10.dat 40 POCTreatment11.dat 41 POCTreatment12.dat 42 POCTreatment13.dat 31 POCTreatment2.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 16 IMPLND 1 COPY 501 COPY 505 COPY 506 COPY 507 COPY 508 COPY 509 COPY 510 COPY 511 COPY 512 COPY 513 COPY 502 DISPLY 1 DISPLY 5 DISPLY 6 DISPLY 7 DISPLY 8 DISPLY 9 DISPLY 10 DISPLY 11 DISPLY 12 DISPLY 13 DISPLY 2 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 5 Basin 5 MAX 1 2 34 9 6 Basin 6 MAX 1 2 35 9 7 Basin 7 MAX 1 2 36 9 8 Basin 8 MAX 1 2 37 9 9 Basin 9 MAX 1 2 38 9 10 Basin 10 MAX 1 2 39 9 11 Basin 11 MAX 1 2 40 9 Treatment 9/9/2025 3:49:44 PM Page 117 12 Basin 12 MAX 1 2 41 9 13 Basin 13 MAX 1 2 42 9 2 Basin 2 MAX 1 2 31 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 505 1 1 506 1 1 507 1 1 508 1 1 509 1 1 510 1 1 511 1 1 512 1 1 513 1 1 502 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 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 *** Treatment 9/9/2025 3:49:44 PM Page 118 # - # 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 *** 1 ROADS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 4 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 16 0.45 COPY 501 12 PERLND 16 0.45 COPY 501 13 IMPLND 1 0.95 COPY 501 15 Basin 5*** PERLND 16 0.27 COPY 505 12 PERLND 16 0.27 COPY 505 13 Treatment 9/9/2025 3:49:44 PM Page 119 IMPLND 1 1.86 COPY 505 15 Basin 6*** PERLND 16 0.11 COPY 506 12 PERLND 16 0.11 COPY 506 13 IMPLND 1 0.98 COPY 506 15 Basin 7*** PERLND 16 0.04 COPY 507 12 PERLND 16 0.04 COPY 507 13 IMPLND 1 3.73 COPY 507 15 Basin 8*** PERLND 16 1.57 COPY 508 12 PERLND 16 1.57 COPY 508 13 IMPLND 1 6.93 COPY 508 15 Basin 9*** IMPLND 1 2.72 COPY 509 15 Basin 10*** PERLND 16 0.1 COPY 510 12 PERLND 16 0.1 COPY 510 13 IMPLND 1 0.11 COPY 510 15 Basin 11*** PERLND 16 0.24 COPY 511 12 PERLND 16 0.24 COPY 511 13 IMPLND 1 0.58 COPY 511 15 Basin 12*** PERLND 16 0.27 COPY 512 12 PERLND 16 0.27 COPY 512 13 IMPLND 1 0.51 COPY 512 15 Basin 13*** PERLND 16 0.06 COPY 513 12 PERLND 16 0.06 COPY 513 13 IMPLND 1 0.4 COPY 513 15 Basin 2*** IMPLND 1 1.91 COPY 502 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 COPY 505 OUTPUT MEAN 1 1 48.4 DISPLY 5 INPUT TIMSER 1 COPY 506 OUTPUT MEAN 1 1 48.4 DISPLY 6 INPUT TIMSER 1 COPY 507 OUTPUT MEAN 1 1 48.4 DISPLY 7 INPUT TIMSER 1 COPY 508 OUTPUT MEAN 1 1 48.4 DISPLY 8 INPUT TIMSER 1 COPY 509 OUTPUT MEAN 1 1 48.4 DISPLY 9 INPUT TIMSER 1 COPY 510 OUTPUT MEAN 1 1 48.4 DISPLY 10 INPUT TIMSER 1 COPY 511 OUTPUT MEAN 1 1 48.4 DISPLY 11 INPUT TIMSER 1 COPY 512 OUTPUT MEAN 1 1 48.4 DISPLY 12 INPUT TIMSER 1 COPY 513 OUTPUT MEAN 1 1 48.4 DISPLY 13 INPUT TIMSER 1 COPY 502 OUTPUT MEAN 1 1 48.4 DISPLY 2 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 Treatment 9/9/2025 3:49:44 PM Page 120 PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL COPY 5 OUTPUT MEAN 1 1 48.4 WDM 705 FLOW ENGL REPL COPY 505 OUTPUT MEAN 1 1 48.4 WDM 805 FLOW ENGL REPL COPY 6 OUTPUT MEAN 1 1 48.4 WDM 706 FLOW ENGL REPL COPY 506 OUTPUT MEAN 1 1 48.4 WDM 806 FLOW ENGL REPL COPY 7 OUTPUT MEAN 1 1 48.4 WDM 707 FLOW ENGL REPL COPY 507 OUTPUT MEAN 1 1 48.4 WDM 807 FLOW ENGL REPL COPY 8 OUTPUT MEAN 1 1 48.4 WDM 708 FLOW ENGL REPL COPY 508 OUTPUT MEAN 1 1 48.4 WDM 808 FLOW ENGL REPL COPY 9 OUTPUT MEAN 1 1 48.4 WDM 709 FLOW ENGL REPL COPY 509 OUTPUT MEAN 1 1 48.4 WDM 809 FLOW ENGL REPL COPY 10 OUTPUT MEAN 1 1 48.4 WDM 710 FLOW ENGL REPL COPY 510 OUTPUT MEAN 1 1 48.4 WDM 810 FLOW ENGL REPL COPY 11 OUTPUT MEAN 1 1 48.4 WDM 711 FLOW ENGL REPL COPY 511 OUTPUT MEAN 1 1 48.4 WDM 811 FLOW ENGL REPL COPY 12 OUTPUT MEAN 1 1 48.4 WDM 712 FLOW ENGL REPL COPY 512 OUTPUT MEAN 1 1 48.4 WDM 812 FLOW ENGL REPL COPY 13 OUTPUT MEAN 1 1 48.4 WDM 713 FLOW ENGL REPL COPY 513 OUTPUT MEAN 1 1 48.4 WDM 813 FLOW ENGL REPL COPY 2 OUTPUT MEAN 1 1 48.4 WDM 702 FLOW ENGL REPL COPY 502 OUTPUT MEAN 1 1 48.4 WDM 802 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** Treatment 9/9/2025 3:49:44 PM Page 121 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 Treatment 9/9/2025 3:49:44 PM Page 122 Predeveloped HSPF Message File Treatment 9/9/2025 3:49:44 PM Page 123 Mitigated HSPF Message File Treatment 9/9/2025 3:49:45 PM Page 124 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2025; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com 1 April 2025 GENERAL USE LEVEL DESIGNATION FOR BASIC (TSS), METALS, PHOSPHORUS & OIL TREATMENT For CONTECH Engineered Solutions Filterra® Ecology’s Decision: Based on the Contech Engineered Solution’s (Contech) submissions for the Filterra® system, Ecology hereby issues the following use level designation: 1. A General Use Level Designation for Basic, Metals, Phosphorus, and Oil Treatment for the Filterra system constructed with a minimum media thickness of 21 inches (1.75 feet), at the following water quality design hydraulic loading rates: Treatment Infiltration Rate (in/hr) for use in Sizing Basic 324 Phosphorus 324 Oils 50 Metals 324 2. The Filterra is not appropriate for oil spill-control purposes. 3. Maintenance data collected during the initial TAPE GULD testing and the post GULD maintenance assessment demonstrated the system was able to treat the following percentage of a water year before needing maintenance: Site Location Land Use Average TSS (mg/L) D50 PSD (µm) Maintenance Cycle1 (% water year) GULD Testing2 Hillsboro, OR Commercial 57 143 723 Maintenance4 Assessment 1 Ecology recommends considering maintenance cycle information when sizing the system. Sizing may need to be increased to meet the project, permit, or jurisdiction maintenance cycle. 2 GULD Testing data is based on 2021-2023 field evaluation that was done to support an infiltration rate of 324 in/hr. 3 Percent water year between maintenance events was not reported. On average maintenance was completed every 8.6 months which was estimated as 72% of a water year. Maintenance was performed according to manufacturer’s typical recommendation and not due to premature bypass or evidence of system occlusion. 4 Maintenance assessment data are collected after issuing of the GULD. Maintenance assessment must be completed on a standard precast Filterra or Filterra Bioscape and shall be completed by February 28, 2028. 2 4. Ecology approves Filterra systems for treatment at the hydraulic loading rates listed above, and sized based on the water quality design flow rate for an off-line system. Calculate the water quality design flow rates using the following procedures: • Western Washington: for treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute flow rate as calculated using the latest version of the Western Washington Hydrology Model or other Ecology-approved continuous runoff model and as described in section III-2.6 of the 2024 Stormwater Management Manual for Western Washington (SWMMWW) • Eastern Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute flow rate as calculated using one of the three methods described in Chapter 6.5.1 of the 2024 Stormwater Management Manual for Eastern Washington (SWMMEW) or local manual. • Entire State: For treatment installed downstream of detention, the water quality design flow rate is the full 2-year release rate of the detention facility. 5. This General Use Level Designation has no expiration date, but Ecology may revoke or amend the designation, and is subject to the conditions specified below. Ecology’s Conditions of Use: Filterra systems shall comply with these conditions shall comply with the following conditions: 1. Design, assemble, install, operate, and maintain the Filterra systems in accordance with applicable Contech Filterra manuals and this Ecology Decision. 2. The minimum size filter surface-area for use in Washington is determined by using the design water quality flow rate (as determined in this Ecology Decision, Item 3, above) and the Infiltration Rate from the table above (use the lowest applicable Infiltration Rate depending on the level of treatment required). Calculate the required area by dividing the water quality design flow rate (cu-ft/sec) by the Infiltration Rate (converted to ft/sec) to obtain required surface area (sq-ft) of the Filterra unit. 3. Each site plan must undergo Contech Filterra review before Ecology can approve the unit for site installation. This will ensure that design parameters including site grading and slope are appropriate for use of a Filterra unit. 4. Filterra media shall conform to the specifications submitted to and approved by Ecology and shall be sourced from Contech with no substitutions. 5. Contech tested the Filterra with and without plants. The GULD applies to the Filterra whether plants are included in the final product or not. 6. Maintenance: The required maintenance interval for stormwater treatment devices is often dependent upon the degree of pollutant loading from a particular drainage basin. Therefore, Ecology does not endorse or recommend a “one size fits all” maintenance cycle for a particular model/size of manufactured treatment device. • Contech designs Filterra systems for a target maintenance interval of 6 months in the Pacific Northwest. Maintenance includes removing and replacing the mulch layer above 3 the media along with accumulated sediment, trash, and captured organic materials therein, evaluating plant health, and pruning the plant if deemed necessary. • Owners/operators must inspect the Filterra system for a minimum of twelve months from the start of post-construction operation to determine site-specific inspection/maintenance schedules and requirements. Owners/operators must conduct inspections monthly during the wet season, and every other month during the dry season (According to the SWMMWW, the wet season in western Washington is October 1 to April 30. According to the SWMMEW, the wet season in eastern Washington is October 1 to June 30). After the first year of operation, owners/operators must conduct inspections based on the findings during the first year of inspections. 7. Conduct maintenance following manufacturer’s guidelines. Follow maintenance procedures given in the most recent version of the Filterra Operation and Maintenance Manual. 8. Filterra systems come in standard sizes. 9. Install the Filterra in such a manner that flows exceeding the maximum operating rate are conveyed around the mulch and media and will not resuspend captured sediment. 10. Discharges from the Filterra units shall not cause or contribute to water quality standards violations in receiving waters. Approved Alternate Configurations Filterra Internal Bypass - Pipe (FTIB-P) 1. The Filterra® Internal Bypass – Pipe allows for piped-in flow from area drains, grated inlets, trench drains, and/or roof drains. Design capture flows and peak flows enter the structure through an internal slotted pipe. Filterra® inverted the slotted pipe to allow design flows to drop through to a series of splash plates that then disperse the design flows over the top surface of the Filterra® planter area. Higher flows continue to bypass the slotted pipe and convey out the structure. 2. To select a FTIB-P unit, the designer must determine the size of the standard unit using the sizing guidance described above. Filterra Internal Bypass – Curb (FTIB-C) 1. The Filterra® Internal Bypass –Curb model (FTIB-C) incorporates a curb inlet, biofiltration treatment chamber, and internal high flow bypass in one single structure. Filterra® designed the FTIB-C model for use in a “Sag” or “Sump” condition and will accept flows from both directions along a gutter line. An internal flume tray weir component directs treatment flows entering the unit through the curb inlet to the biofiltration treatment chamber. Flows in excess of the water quality treatment flow rise above the flume tray weir and discharge through a standpipe orifice; providing bypass of untreated peak flows. Americast manufactures the FTIB-C model in a variety of sizes and configurations and you may use the unit on a continuous grade when a single structure providing both treatment and high flow bypass is preferred. The FTIB-C model can also incorporate a separate junction box chamber to allow larger diameter discharge pipe connections to the structure. 4 2. To select a FTIB-C unit, the designer must determine the size of the standard unit using the sizing guidance described above. Filterra® Shallow 1. The Filterra Shallow provides additional flexibility for design engineers and designers in situations where various elevation constraints prevent application of a standard Filterra configuration. Engineers can design this system up to six inches shallower than any of the previous Filterra unit configurations noted above. 2. Ecology requires that the Filterra Shallow provide a media contact time equivalent to that of the standard unit. This means that with a smaller depth of media, the surface area must increase. 3. To select a Filterra Shallow System unit, the designer must first identify the size of the standard unit using the modeling guidance described above. 4. Once the size of the standard Filterra unit is established using the sizing technique described above, use information from the following table to select the appropriate size Filterra Shallow System unit. Shallow Unit Basic, Metals, Phosphorus, and Oil Treatment Sizing Standard Depth Equivalent Shallow Depth 4x4 4x6 or 6x4 4x6 or 6x4 6x6 4x8 or 8x4 6x8 or 8x6 6x6 6x10 or 10x6 6x8 or 8x6 6x12 or 12x6 6x10 or 10x6 13x7 Notes: 1. Shallow Depth Boxes are less than the standard depth of 3.5 feet but no less than 3.0 feet deep (TC to INV). Applicant: Contech Engineered Solutions, LLC. Applicant’s Address: 12901 SE 97th Ave, Suite 400 Clackamas, OR 97015 Application Documents: State of Washington Department of Ecology Application for Conditional Use Designation, Americast (September 2006) Quality Assurance Project Plan Filterra® Bioretention Filtration System Performance Monitoring, Americast (April 2008) Quality Assurance Project Plan Addendum Filterra® Bioretention Filtration System Performance Monitoring, Americast (June 2008) 5 Draft Technical Evaluation Report Filterra® Bioretention Filtration System Performance Monitoring, Americast (August 2009) Final Technical Evaluation Report Filterra® Bioretention Filtration System Performance Monitoring, Americast (December 2009) Technical Evaluation Report Appendices Filterra® Bioretention Filtration System Performance Monitoring, Americast, (August 2009) Memorandum to Department of Ecology Dated October 9, 2009 from Americast, Inc. and Herrera Environmental Consultants Quality Assurance Project Plan Filterra® Bioretention System Phosphorus treatment and Supplemental Basic and Enhanced Treatment Performance Monitoring, Americast (November 2011) Filterra® letter August 24, 2012 regarding sizing for the Filterra® Shallow System. University of Virginia Engineering Department Memo by Joanna Crowe Curran, Ph. D dated March 16, 2013 concerning capacity analysis of Filterra® internal weir inlet tray. Terraphase Engineering letter to Jodi Mills, P.E. dated April 2, 2013 regarding Terraflume Hydraulic Test, Filterra® Bioretention System and attachments. Technical Evaluation Report, Filterra® System Phosphorus Treatment and Supplemental Basic Treatment Performance Monitoring. March 27th, 2014. State of Washington Department of Ecology Application for Conditional Use Level Designation, Contech Engineered Solutions (May 2015) Quality Assurance Project Plan Filterra® Bioretention System, Contech Engineered Solutions (May 2015) Filterra Bioretention System Armco Avenue General Use Level Designation Technical Evaluation Report, Contech Engineered Solutions (August 2019) NJCAT Technology Verification, Filterra Bioretention System, Contech Engineered Solutions (October 2020) Basic Treatment PULD Application for Contech Enhanced Filtration System, Contech Engineered Solutions (November 2020) Contech Enhanced Filtration System, Application for Certification, Contech Engineered Solutions (November 2020) Quality Assurance Project Plan Contech Enhanced Filtration System (CEFS) Technology Performance Evaluation, Prepared by Contech Engineered Solutions (September 2021) Addendum to the Quality Assurance Project Plan – Contech Enhanced Filtration System, Prepared by Contech Engineered Solutions (August 2021) Contech Enhanced Filtration System Armco Avenue General Use Level Designation Technical Evaluation Report, Prepared by Contech Engineered Solutions (May 2024) Applicant’s Use Level Request: General Level Use Designation as a Basic, Metals, Phosphorus, and Oil Treatment device in accordance with Ecology’s Stormwater Management Manual for Western Washington. Applicant’s Performance Claims: Based on field testing, the Filterra is able to meet TAPE performance goals for TSS, dissolved metals, and total phosphorus at an infiltration rate of 324 in/hr, and is able to meet TAPE 6 performance goals for oil at an infiltration rate of 50 in/hr. Ecology’s Recommendations: Ecology finds that Contech has shown Ecology, through laboratory and field testing, that the Filterra is capable of attaining Ecology’s Basic, Metals, Phosphorus, and Oil treatment goals. Findings of Fact: Field Testing 2021-2023 1. Contech completed field testing of a 4 ft. x 3 ft. unvegetated Filterra unit (referred to as a Contech Enhanced Filtration System [CEFS] during testing) in Hillsboro, Oregon between June 2021 and April 2023. Throughout the monitoring period a total of 35 individual storm events were sampled. 2. The CEFS utilized the same media formulation and dimensional layout as a Filterra unit but did not include plants. 3. Contech evaluated the system for basic, metals, and phosphorus treatment against a hydraulic loading rate of 3.36 gpm/sf (324 in/hr). 4. Herrera Environmental Consultants conducted a third-party review of the data and TER to ensure the monitoring complied with the QAPP and met the requirements of the TAPE guidance document. 5. Particle size distribution analysis showed 39% of the influent particulate finer than 62.5 microns (µm) for the samples collected during the 35-event period. Performance analysis based on serial filtration demonstrated that TSS for a majority-silt sediment range met Basic treatment requirements with an upper 95 percent confidence limit (UCL95) effluent concentration of 18.8 mg/L. 6. The similarity of influent and effluent PSD prompted a review of the influence of laboratory procedure on the results. Upon recommendation of Herrera Environmental Consultants, a secondary laboratory was consulted which provided TAPE PSD analysis on multiple previous TAPE testing campaigns, including the Ship Canal test site. Six supplemental events were sampled for PSD between 1/4/24 and 2/16/24, and sample splits were sent for comparative analysis by both laboratories. Results from the second laboratory showed 77% of influent particulate finer than 62.5 microns (µm). Average influent D50 results for the six events were 159 µm and 12 µm for the original and secondary laboratories, respectively. 7. Of the 35 sampled events, 21 met requirements for TSS analysis. Influent TSS concentrations ranged from 20 mg/L to 269 mg/L, with a mean concentration of 57 mg/L. For samples with an influent concentration between 20 and 100 mg/L (n=17) the upper 95 percent confidence limit of the mean TSS effluent concentration was 17.5 mg/L. For samples with an influent concentration greater than 100 mg/L (n=4) the lower 95 percent confidence limit of the mean TSS reduction was 83.5%. Influent concentrations greater than 200 mg/L (the upper end of the TAPE influent concentration range) were capped at 200 mg/L before calculating the pollutant removal efficiency. 8. Of the 35 sampled events, 27 met requirements for dissolved copper analysis. Influent dissolved copper concentrations ranged from 7.3 µg/L to 46.0 µg/L, with a mean 7 concentration of 18.1 µg/L. The lower 95 percent confidence limit of the mean dissolved copper reduction was 39.8%. Influent concentrations greater than 20 µg/L (the upper end of the TAPE influent concentration range) were capped at 20 µg/L before calculating the pollutant removal efficiency. 9. Of the 35 sampled events, 28 met requirements for dissolved zinc analysis. Influent dissolved zinc concentrations ranged from 33.9 µg/L to 178.0 µg/L, with a mean concentration of 74.4 µg/L. The lower 95 percent confidence limit of the mean dissolved zinc reduction was 62.4%. 10. Of the 35 sampled events, 16 met requirements for the total phosphorus analysis. Influent total phosphorus concentrations ranged from 0.101 mg/L to 0.571 mg/L with a mean concentration of 0.298 mg/L. The lower 95 percent confidence limit of the mean total phosphorus reduction was 64.4%. 11. Maintenance was conducted 3 times during the 23-month study period with frequency ranging from every 4 to 9 months. Maintenance performed consisted of replacing the mulch layer. Field Testing 2015-2019 1. Contech completed field testing of a 4 ft. x 4 ft. Filterra unit at one site in Hillsboro, Oregon from September 2015 to July 2019. Throughout the monitoring period a total of 24 individual storm events were sampled, of which 23 qualified for TAPE sampling criteria. 2. Contech encountered several unanticipated events and challenges that prevented them from collecting continuous flow and rainfall data. An analysis of the flow data from the sampled events, including both the qualifying and non-qualifying events, demonstrated the system treated over 99% of the influent flows. Peak flows during these events ranged from 25% to 250% of the design flow rate of 29 gallons per minute. 3. Of the 23 TAPE qualified sample events, 13 met requirements for TSS analysis. Influent concentrations ranged from 20.8 mg/L to 83 mg/L, with a mean concentration of 46.3 mg/L. The UCL95 mean effluent concentration was 15.9 mg/L, meeting the 20 mg/L performance goal for Basic Treatment. 4. All 23 TAPE qualified sample events met requirements for dissolved zinc analysis. Influent concentrations range from 0.0384 mg/L to 0.2680 mg/L, with a mean concentration of 0.0807 mg/L. The LCL 95 mean percent removal was 62.9%, meeting the 60% performance goal for Metals Treatment. 5. Thirteen of the 23 TAPE qualified sample events met requirements for dissolved copper analysis. Influent concentrations ranged from 0.00543 mg/L to 0.01660 mg/L, with a mean concentration of 0.0103 mg/L. The LCL 95 mean percent removal was 41.2%, meeting the 30% performance goal for Metals Treatment. 6. Total zinc concentrations were analyzed for all 24 sample events. Influent EMCs for total zinc ranged from 0.048 mg/L to 5.290 mg/L with a median of 0.162 mg/L. Corresponding effluent EMCs for total zinc ranged from 0.015 mg/L to 0.067 mg/L with a median of 0.029 mg/L. Total event loadings for the study for total zinc were 316.85 g at the influent and 12.92 g at the effluent sampling location, resulting in a summation of loads removal efficiency of 95.9%. 8 7. Total copper concentrations were analyzed for all 24 sample events. Influent EMCs for total copper ranged from 0.003 mg/L to 35.600 mg/L with a median value of 0.043 mg/L. Corresponding effluent EMCs for total copper ranged from 0.002 mg/L to 0.015 mg/L with a median of 0.004 mg/L. Total event loadings for total copper for the study were 1,810.06 g at the influent and 1.90 g at the effluent sampling location, resulting in a summation of loads removal efficiency of 99.9%. Field Testing 2013 1. Filterra completed field-testing of a 6.5 ft x 4 ft. unit at one site in Bellingham, Washington. Continuous flow and rainfall data collected from January 1, 2013 through July 23, 2013 indicated that 59 storm events occurred. Water quality data was obtained from 22 storm events. Not all the sampled storms produced information that met TAPE criteria for storm and/or water quality data. 2. The system treated 98.9% of the total 8-month runoff volume during the testing period. Consequently, the system achieved the goal of treating 91% of the volume from the site. Stormwater runoff bypassed Filterra treatment during four of the 59 storm events. 3. Of the 22 sampled events, 18 qualified for TSS analysis (influent TSS concentrations ranged from 25 to 138 mg/L). The data were segregated into sample pairs with influent concentration greater than and less than 100 mg/L. The UCL95 mean effluent concentration for the data with influent less than 100 mg/L was 5.2 mg/L, below the 20- mg/L threshold. Although the TAPE guidelines do not require an evaluation of TSS removal efficiency for influent concentrations below 100 mg/L, the mean TSS removal for these samples was 90.1%. Average removal of influent TSS concentrations greater than 100 mg/L (three events) was 85%. In addition, the system consistently exhibited TSS removal greater than 80% at flow rates equivalent to a 100 in/hr infiltration rate and was observed at 150 in/hr. 4. Ten of the 22 sampled events qualified for TP analysis. Americast augmented the dataset using two sample pairs from previous monitoring at the site. Influent TP concentrations ranged from 0.11 to 0.52 mg/L. The mean TP removal for these twelve events was 72.6%. The LCL95 mean percent removal was 66.0, well above the TAPE requirement of 50%. Treatment above 50% was evident at 100 in/hr infiltration rate and as high as 150 in/hr. Consequently, the Filterra test system met the TAPE Phosphorus Treatment goal at 100 in/hr. Influent ortho-P concentrations ranged from 0.005 to 0.012 mg/L; effluent ortho-P concentrations ranged from 0.005 to 0.013 mg/L. The reporting limit/resolution for the ortho-P test method is 0.01 mg/L, therefore the influent and effluent ortho-P concentrations were both at and near non-detect concentrations. Field Testing 2008-2009 1. Filterra completed field-testing at two sites at the Port of Tacoma. Continuous flow and rainfall data collected during the 2008-2009 monitoring period indicated that 89 storm events occurred. The monitoring obtained water quality data from 27 storm events. Not 9 all the sampled storms produced information that met TAPE criteria for storm and/or water quality data. 2. During the testing at the Port of Tacoma, 98.96 to 99.89% of the annual influent runoff volume passed through the POT1 and POT2 test systems respectively. Stormwater runoff bypassed the POT1 test system during nine storm events and bypassed the POT2 test system during one storm event. Bypass volumes ranged from 0.13% to 15.3% of the influent storm volume. Both test systems achieved the 91% water quality treatment-goal over the 1-year monitoring period. 3. Consultants observed infiltration rates as high as 133 in/hr during the various storms. Filterra did not provide any paired data that identified percent removal of TSS, metals, oil, or phosphorus at an instantaneous observed flow rate. 4. The maximum storm average hydraulic loading rate associated with water quality data is <40 in/hr, with the majority of flow rates < 25 in/hr. The average instantaneous hydraulic loading rate ranged from 8.6 to 53 in/hr. 5. The field data showed a removal rate greater than 80% for TSS with an influent concentration greater than 20 mg/L at an average instantaneous hydraulic loading rate up to 53 in/hr (average influent concentration of 28.8 mg/L, average effluent concentration of 4.3 mg/L). 6. The field data showed a removal rate generally greater than 54% for dissolved zinc at an average instantaneous hydraulic loading rate up to 60 in/hr and an average influent concentration of 0.266 mg/L (average effluent concentration of 0.115 mg/L). 7. The field data showed a removal rate generally greater than 40% for dissolved copper at an average instantaneous hydraulic loading rate up to 35 in/hr and an average influent concentration of 0.0070 mg/L (average effluent concentration of 0.0036 mg/L). 8. The field data showed an average removal rate of 93% for total petroleum hydrocarbon (TPH) at an average instantaneous hydraulic loading rate up to 53 in/hr and an average influent concentration of 52 mg/L (average effluent concentration of 2.3 mg/L). The data also shows achievement of less than 15 mg/L TPH for grab samples. Filterra provided limited visible sheen data due to access limitations at the outlet monitoring location. 9. The field data showed low percentage removals of total phosphorus at all storm flows at an average influent concentration of 0.189 mg/L (average effluent concentration of 0.171 mg/L). We may relate the relatively poor treatment performance of the Filterra system at this location to influent characteristics for total phosphorus that are unique to the Port of Tacoma site. It appears that the Filterra system will not meet the 50% removal performance goal when the majority of phosphorus in the runoff is expected to be in the dissolved form. Laboratory Testing 1. Contech conducted testing of a 4 ft. x 4 ft. unit in July 2020 at Contech’s laboratory in Ashland, Virginia. The unit included the Filterra® HC media blend without the use of any vegetation that is standard in Filterra installations. • The laboratory testing was performed in accordance with the New Jersey Department of Environmental Protection (NJDEP) Laboratory Protocol to Assess Total 10 Suspended Solids Removal by a Filtration Manufactured Treatment Device. Since Contech did the testing, A. Morton Thomas and Associates, inc. performed independent third-party observation. • The testing evaluated a full-scale 4 ft. x 4 ft. unit at a hydraulic loading rate of 3.12 gpm/sq. ft (300 in/hr). The test sediment used with compliant with the NJDEP particle size distribution requirements, with a d50 particle size of 69 µm. • Contech evaluated TSS removal efficiency over 15 events. The influent concentration ranged from 182 mg/L to 211 mg/L with a mean concentration of 200.7 mg/L and a mean removal efficiency of 86%. • Contech evaluated sediment mass loading capacity over an additional 21 events as a continuation of the removal efficiency testing. During the sediment mass loading capacity evaluation Contech increased the target influent concentration to 400 mg/L. The cumulative removal efficiency over the 36 events was 82% and the cumulative mass captured was 110 kg. 2. Filterra performed laboratory testing on a scaled down version of the Filterra unit. The lab data showed an average removal from 83-91% for TSS with influents ranging from 21 to 320 mg/L, 82-84% for total copper with influents ranging from 0.94 to 2.3 mg/L, and 50-61% for orthophosphate with influents ranging from 2.46 to 14.37 mg/L. • Filterra conducted permeability tests on the soil media. • Lab scale testing using Sil-Co-Sil 106 showed removals ranging from 70.1% to 95.5% with a median removal of 90.7%, for influent concentrations ranging from 8.3 to 260 mg/L. Filterra ran these laboratory tests at an infiltration rate of 50 in/hr. • Supplemental lab testing conducted in September 2009 using Sil-Co-Sil 106 showed an average removal of 90.6%. These laboratory tests were run at infiltration rates ranging from 25 to 150 in/hr for influent concentrations ranging from 41.6 to 252.5 mg/L. Regression analysis results indicate that the Filterra system’s TSS removal performance is independent of influent concentration in the concentration rage evaluated at hydraulic loading rates of up to 150 in/hr. Other Filterra Related Issues to be Addressed by the Company: 1. Conduct hydraulic testing on a standard precast Filterra or Filterra Bioscape at one site in the Pacific Northwest as outlined in the 2024 TAPE Guidance Document to obtain additional information about the maintenance longevity and requirements. Complete testing by February 28, 2028. Technology Description: https://www.conteches.com/stormwater-management/biofiltration- solutions/filterra/ Contact Information: Applicant: Jeremiah Lehman 11 Contech Engineered Solutions, LLC. 12901 SE 97th Ave, Suite 400 Clackamas, OR 97015 (503) 258-3136 jlehman@conteches.com Applicant’s Website: http://www.conteches.com Ecology web link: http://www.ecy.wa.gov/programs/wq/stormwater/newtech/index.html Ecology: Douglas C. Howie, P.E. Department of Ecology Water Quality Program (360) 870-0983 douglas.howie@ecy.wa.gov Date Revision December 2009 GULD for Basic, Enhanced, and Oil granted, CULD for Phosphorus September 2011 Extended CULD for Phosphorus Treatment September 2012 Revised design storm discussion, added Shallow System. January 2013 Revised format to match Ecology standards, changed Filterra contact information February 2013 Added FTIB-P system March 2013 Added FTIB-C system April 2013 Modified requirements for identifying appropriate size of unit June 2013 Modified description of FTIB-C alternate configuration March 2014 GULD awarded for Phosphorus Treatment. GULD updated for a higher flow-rate for Basic Treatment. June 2014 Revised sizing calculation methods March 2015 Revised Contact Information June 2015 CULD for Basic and Enhanced at 100 in/hr infiltration rate September 2019 GULD for Basic and Enhanced at 175 in/hr infiltration rate February 2020 Revised sizing language to note sizing based on off-line calculations June 2020 Added Phosphorus to Filterra Shallow sizing table January 2024 Revised Dissolved Metals (Enhanced) to Metals July 2024 GULD for Basic, Enhanced, and Phosphorus at 324 in/hr infiltration rate for vegetated and unvegetated Filterra systems. Updated Contech address March 2025 Added requirement for maintenance assessment April 2025 Updated Findings of Fact for Field Testing 2021-2023 Technical Information Report New Renton High School Project No. 2230388.10 Appendix E Conveyance Calculations (To be provided in a future submittal) Technical Information Report New Renton High School Project No. 2230388.10 Appendix F TESC Calculations (To be provided in a future submittal) Technical Information Report New Renton High School Project No. 2230388.10 Appendix G Bonds and Covenants (To be provided in a future submittal) Technical Information Report New Renton High School Project No. 2230388.10 Appendix H Operations and Maintenance Manual (To be provided in a future submittal)