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HomeMy WebLinkAboutVarma 3-Lot Short Plat Drainage Report Civil Engineering & Development Services 1700 NW Gilman Blvd., Suite 200; Issaquah, WA 98027 (425) 821-5038 TECHNICAL INFORMATION REPORT CITY OF RENTON For Varma SFR 13014 156th Ave SE Renton, WA 98059 June 13, 2025 Revised 1/29/2026 Prepared For: Kushal Varma 13014 156th Ave SE Renton, WA 98059 Stormwater Technical Information Report Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page i For Full Drainage Review Project Sites Project Name: Varma 3 Lot Short Plat Project Address: 13012 156th Ave SE Renton, WA 98059 Parcel Number(s): 366450-0185 Name of Developer/Owner: Kushal Varma Name of Engineer: Edward Mecum, PE Company: G2 Civil Address: 1700 NW Gilman Blvd., Ste. 200, Issaquah, WA 98027 Phone Number: 425-821-5038 Report Date: January 29, 2026 Engineer’s Stamp: This box to be completed by COK staff PERMIT # Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page ii Table of Contents I. PROJECT OVERVIEW .............................................................................................................. 1 II. CONDITIONS AND REQUIREMENTS SUMMARY ..................................................................... 6 III. DOWNSTREAM ANALYSIS .................................................................................................... 10 IV. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN ........................... 13 V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN .................................................................... 14 VI. SPECIAL REPORTS AND STUDIES .......................................................................................... 14 VII. OTHER PERMITS ................................................................................................................... 14 VIII. CSWPP ANALYSIS AND DESIGN ............................................................................................ 14 IX. BOND QUANTITIES, FACILITY SUMMARIES & DECLARATION of COVENANT ........................ 16 List of Figures Figure 1 – Vicinity Map Figure 2 – Soils Map and Legend Figure 3 – Existing Conditions Map Figure 4 – Developed Conditions Map Figure 5 – Drainage Review Flow Chart Figure 6 – Downstream Map 1 Figure 7 – Downstream Map 2 Appendix A Wetland and Stream Reconnaissance for 13016- 156th Avenue SE, Renton WA by Altmann Oliver Associates, LLC dated January 29, 2020 Appendix B Infiltration Assessment by The Riley Group, Inc. dated September 2, 2020 Geotechnical Engineering Report by The Riley Group, Inc. dated November 10, 2022 Appendix C WWHM Output Appendix D Operations and Maintenance Manual Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 1 I. PROJECT OVERVIEW Project: Varma SFR Site Address: 13014 156th Ave SE Tax Parcel #: 3664500185 Zoning District: R-4, Residential Site Area: Total Lot Area = 45,872 SF (1.05 Acres) Site Location: The site is in the City of Renton within the NW ¼ of the NE ¼ of Section 14, Township 23 North, Range 5 East, W.M, King County, Washington. Figure 1: Vicinity Map SITE Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 2 Pre-developed Site Conditions The project site is within the City of Renton. The site is accessed from 156th Ave SE, approximately 250 feet north of the intersection of SE 132nd St and 156th Ave SE. The site is bordered to the north, south and east by single-family residences, and to the west 156th Ave SE. The project site currently consists of an existing single-family residence with a driveway and associated walks and patio areas. The house was permitted and completed in 2024 with all impervious surfaces mitigated for stormwater runoff. The site is gently sloped to the from the north to the south at a slope of 2% and has a slight ridge from the northwest corner toward the middle of the south property line. The property is located within the Lower Cedar River drainage basin. Runoff from the site is divided into two separate flow paths that follow 156th and 158th Avenues. See full downstream analysis in Section III. Critical Areas According to COR Maps, and the Wetland and Stream Reconnaissance dated January 29, 2020 (Appendix A), no critical areas are located on or adjacent to the project site. Soils Per the US Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS) Web Soil Survey (WSS) information, the entire project site is underlain with Alderwood gravelly sandy loam, 8 to 15 percent slopes (See Figure 3 on the following page). Soils encountered in on- site investigations include medium dense silty sand with gravel over very dense glacial till per the Geotechnical Engineering Report prepared by The Riley Group, Inc. (Appendix B). Figure 2: Soil Map and Legend SITE Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 3 EAST BASIN Figure 3: Existing Conditions Map N Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 4 Developed Site Conditions The proposed project will divide the existing parcel into three single family residential parcels, retaining the existing residence. An access and utilities tract will provide service to each of the new lots from 156th Ave SE along the north property line, utilizing the existing driveway and expanding the width as needed to meet access requirements. Site runoff will be mitigated via basic dispersion to maintain the existing drainage patterns within the two previously defined, on- site drainage basins. Since the frontage improvements were installed during the construction of the existing residence, work within the Right of Way is limited to utility service installations, which will not result in additional impervious surfaces. Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 5 FIGURE 4: Developed Conditions Map Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 6 II. CONDITIONS AND REQUIREMENTS SUMMARY The 2022 City of Renton Surface Water Design Manual (RSWDM) was utilized to determine and address all core and special requirements. The short plat is not a single family, residential project and will result in approximately 8,282 square feet of new impervious surfaces. Based on the criteria specified in Figure 1.1.2.A of the RSWDM, the project falls under Full Drainage Review. Per Section 1.1.2.3 of the RSWDM, the project must meet all nine (9) core and all six (6) special requirements. See Figure 5 below for more information on how the type of drainage review was determined. Figure 5: Drainage Review Flow Chart Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 7 Core Requirements Core Requirement #1: Discharge at the Natural Location The proposed development will perpetuate the existing drainage patterns for both drainage basins. Refer to the Level 1 Downstream Analysis in Section III of this TIR for a complete description of the existing drainage paths. Core Requirement #2: Downstream Analysis A Level 1 Downstream analysis has been completed for the project, and no existing or potential problems have been identified. This analysis is included in Section III of this TIR. Core Requirement #3: Flow Control The project is exempt from flow control based on the modeled increase in stormwater runoff. This has been achieved by limiting the roof area of the two new residences expected to be built and routing the runoff from the two roofs to basic dispersion trenches on the downhill side (rear) of each house. The increased runoff from the proposed project does not exceed the permissible increased runoff rate of 0.15cfs. See Section IV. Core Requirement #4: Conveyance System The proposed on-site conveyance system, dispersion and grading will route runoff to the natural discharge point. The low flows associated with the roof runoff for each residence may be addressed under their individual building permit reviews, but is expected to be negligible. Please refer to Section V for the conveyance system analysis. Core Requirement #5: Construction Stormwater Pollution Prevention A temporary erosion and sediment control (TESC) plan providing details on best management practices (BMPs) to be implemented during construction is included in the engineering plan set and in the separate CSWPPP that addresses the required 13 sections. 1. Clearing Limits 2. Cover Measures 3. Perimeter Protection 4. Traffic Area Stabilization 5. Sediment Retention 6. Surface Water Collection 7. Dewatering Control 8. Dust Control 9. Flow Control 10. Control Pollutants 11. Protect Existing and Proposed Stormwater Facilities and On-site BMPs 12. Maintain Protective BMPs 13. Manage the Project Core Requirement #6: Maintenance and Operations An Operation and Maintenance Manual will be provided in Appendix D upon review and acceptance of the drainage design. Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 8 Core Requirement #7: Financial Guarantees and Liability The owner will arrange for any financial guarantees and liabilities required by the permit. Core Requirement #8: Water Quality Facilities The proposed pollution-generating impervious surface installed by the proposed project is limited to the shared driveway within Tract A and individual driveways for the new parcels. The existing driveway beyond the tract for Lot 3 will remain in place and is not considered to be a target surface. The Pollution Generating Impervious Surface (PGIS) is divided almost evenly between the two drainage basins with 1,006 square feet being created in the west basin and 1,076 square feet in the east basin. Each and the total is less than the 5,000 SF threshold; therefore water quality treatment is not required or provided. Core Requirement #9: On-Site BMPs This project is classified as a Subdivision in the 2022 Renton Surfacer Water Design Manual. On-Site BMP’s for subdivision infrastructure such as roads and sidewalk must be implemented in accordance with 1.2.9.3.2 – Small Road Improvement Projects. Single- Family residences will be responsible for design and installation of On-Site BMP’s at the time of building permit application. The BMP’s for the residences have been loosely defined as providing basic dispersion using a dispersion trench sized for the restricted roof area of 3100 square feet per residence. Additional square footage will need to be mitigated fully to maintain the flow control exemption of the short plat. Impervious Surface BMP Evaluation 1. Full Dispersion: Infeasible. The space required for a 100-foot native vegetated flow-path segment is not available downstream of the target surfaces and the parcel could not support the NGRA requirement. 2. Target impervious surfaces not mitigated by full dispersion must implement BMP’s from the following list to the maximum extnent feasible. a. Full Infiltration: Infeasible. The Geotechnical Engineering Report prepared by The Riley Group, Inc. dated November 10, 2022 (Appendix B) states that infiltration is infeasible at the site due to underlain glacial till and confirmed by an in-situ infiltration test. b. Limited Infiltration: Infeasible. BMP’s relying on infiltration are not feasible as described above. c. Bioretention is infeasible due to the site’s inability to infiltrate runoff. d. Permeable Pavement: Infeasible. BMP’s relying on infiltration are not feasible as described above. 3. All target impervious surfaces not mitigated by Requirements 1 and 2 above must be mitigated to the maximum extent feasible using Basic Dispersion. a. Basic Dispersion: FEASIBLE. Sheet flow dispersion from the access road is proposed where individual driveways will not interfere with the required flow path. The future residences are scheduled to install basic dispersion trenches to accommodate the entire roof area on each new parcel. Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 9 4. Soil Amendment: Feasible. All disturbed, pervious areas of the project will meet soil amendment requirements as detailed in Section C.2.13 of the 2022 RSWDM. Special Requirements Special Requirement #1: Other Adopted Area-Specific Requirements Master Drainage Plans– N/A Basin Plan – N/A Salmon Conservation Plans- N/A Lake Management Plans – N/A Hazard Mitigation Plan- N/A Shared Facility Drainage Plans – N/A Special Requirement #2: Flood Hazard Area Delineation The limits of this project do not lie within a delineated FEMA 100-year floodplain. Special Requirement #3: Flood Protection Facilities This project does not rely on or propose to modify/construct a new flood protection facility. Special Requirement #4: Source controls The project is not a commercial building or development; therefore, this requirement is not applicable. Special Requirement #5: Oil Control This project is not considered high use in need of oil control. Special Requirement #6: Aquifer Protection Area The site is not located within an Aquifer Protection Area. Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 10 III. DOWNSTREAM ANALYSIS A Level 1 Offsite Analysis has been performed for the project site per Section 1.2.2.1 of the 2017 City of Renton Surface Water Design Manual by an engineer under my supervision on Wednesday June 10, 2020. The analysis was performed at approximately 3:30 PM with a temperature of about 75°. Soil conditions were observed to be saturated. The property is currently undeveloped and has been partially cleared by previous development to the north. The site is situated within a single drainage basin, the Lower Cedar River, but discharges from two separate locations. The two flow paths do not converge within ¼ mile downstream of the site, and therefore two Level 1 downstream analyses are required for this project. A map showing the study area is included see Figures 6 & 7 on the following pages. We have reviewed the site and the applicable resources for both listed and potential problems. The receiving waterbody, Lower Cedar River, is impaired at a Category 5 – 303d level for pH, Temperature, and Dissolved Oxygen per the Washington Department of Ecology Water Quality Atlas. No other critical areas or critical area buffers were located on the site per King County iMap, the City of Renton GIS maps, FEMA maps, or the CED Wetlands Inventory. The site is divided into two drainage basins with a total area of 1.07 acres which does not include the frontage improvements. An approximate “basin line” has been added to the downstream map to reflect this information. The western basin directs stormwater runoff west towards the 156th Avenue SE system as detailed below. The eastern basin directs stormwater runoff south and east towards the 158th Avenue SE system as detailed below. The eastern basin will remain undeveloped. Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 11 Figure 6: Downstream Map 1 Figure 7: Downstream Map 2 WEST EAST MATCHLINE APPROXIMATE BASIN LINE Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 12 East Basin The Eastern Drainage basin, detailed in this Analysis, is approximately 0.76 acres in size. Slopes range from 1-4% across the site. The study area for this analysis extends downstream for approximately one quarter mile and includes no upstream offsite drainage area tributary to the project site. The neighboring property to the north, while located at a higher elevation, has been previously developed and does not direct significant stormwater runoff to the subject property. Stormwater runoff from the eastern basin sheet flows to the south and east across the property line where it enters a stormwater ditch along the west side of 158th Ave SE. This ditch conveys flows south along 158th Ave SE through a series of culverts for driveway access. Runoff is then directed into sections of 12” Polyethylene culverts which convey stormwater under NE 1st St. The 158th Ave SE system collects runoff via catch basins within the public right-of-way as well as tie- ins from other residential development. The 12” Polyethylene pipe discharges to a series of stormwater ditches which are interrupted by 12” Polyethylene culverts and a 12” Concrete culvert for conveyance under driveway accesses. Stormwater is then directed into the SE 2nd Pl system which ultimately discharges runoff into the Lower Cedar River and the Lake Washington watershed. This Analysis was ended at a point over ¼ mile downstream of the site discharge location. West Basin The Western Drainage basin, detailed in this Analysis, is approximately 0.31 acres in size. Slopes range from 1-4% across the site. The study area for this analysis extends downstream for approximately one quarter mile and includes no upstream offsite drainage area tributary to the project site. The neighboring property to the north, while located at a higher elevation, has been previously developed and does not direct significant stormwater runoff to the subject property. Stormwater runoff from the western basin sheet flows to the south and west across the property line where it enters a stormwater ditch along the east side of 156th Ave SE. This ditch conveys flows south along 156th Ave SE through a series of culverts for driveway access. Runoff is then directed into a 12” Concrete culvert which marks the beginning of the 156th Ave SE closed conveyance system. This continues to direct flows south into a section of 12” Ductile Iron pipe which transitions to 12” Polyethylene pipe. This system collects runoff via catch basins within the public right-of-way as well as tie-ins from other residential development. The 12” Polyethylene pipe continues to convey stormwater south, and ultimately discharges runoff into the Lower Cedar River and the Lake Washington watershed. This Analysis was ended at a point over ¼ mile downstream of the site discharge location. Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 13 IV. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN The site was analyzed using the Western Washington Hydrology Model (WWHM) provided by the Department of Ecology (DOE). We are only modeling the portion of the site that’s being developed. The project site is in a Level 2 Flow Control Area, therefore forested conditions have been used for the pre-developed modeling analysis. The hydrologic analysis of the site was completed to determine the increase in 100-year peak. Per Section 1.2.3.1.A, a formal flow control facility is waived for any threshold discharge area in which the target surfaces will generate no more than a 0.15 CFS increase (utilizing 15-minute timesteps) in the existing site conditions 100-year peak flow. The WWHM analysis concluded that the increase in the 100-year peak is less than 0.15 CFS for each basin, therefore a formal flow control facility is not required. The site basin area breakdown is summarized below. Refer to Appendix A for the complete WWHM analysis. SF AC MIT % LAWN TOTAL 14716 0.338 ROAD 506 0.012 10% 500 0.010 0.001 ROOF 3100 0.071 10% 2,879 0.064 0.007 DRIVEWAY 500 0.011 10% 494 0.010 0.001 LAWN 10,842 0.249 Totals 3,874 0.085 0.009 Pre-Dev Developed Increase 0.0526 0.202 0.1494 SF AC MIT % LAWN TOTAL 11845 0.272 ROAD 576 0.013 10% 568 576 0.0130 ROOF 3100 0.071 10% 2,879 3,100 0.0661 DRIVEWAY 500 0.011 10% 494 500 0.0113 LAWN 7,903 0.1814 Totals 3,942 4,176 0.0905 Pre-Dev Developed Increase 0.0423 0.1904 0.1481Modeled Flow Rate EFF IA EFF IA Modeled Flow Rate BASIN 1 (West) BASIN 2 (East) Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 14 V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN The runoff from the proposed on-site storm drainage does not warrant a conveyance system analysis all runoff associated with the subdivision will sheet flow for basic dispersion. The frontage improvements have been completed under the construction of the single family and addressed offsite flow rates. Any piped storm conveyance associated with the future single family residences will be assessed during the drainage review of those projects. VI. SPECIAL REPORTS AND STUDIES • Infiltration Assessment by The Riley Group, Inc. dated September 2, 2020 • Geotechnical Engineering Report by The Riley Group, Inc. dated November 10, 2022 • Wetland and Stream Reconnaissance for 13016- 156th Ave. SE Renton WA by Altmann Oliver Associates, LLC, dated January 29, 2020. VII. OTHER PERMITS • Civil Construction Permit • Final Short Plat • Building Permits • Right-of-Way Use Permit • WD 90 Water Service Applications VIII. CSWPP ANALYSIS AND DESIGN Erosion/Sedimentation Control Design: Several standard Best Management Practices (BMP’s) per CORSWDM Appendix D.3 will be utilized by the contractor to minimize the amount of erosion and sedimentation that may be perpetuated by the construction of the site. The thirteen erosion and sedimentation control measures are outlined below: Clearing Limits- Prior to any site clearing, the areas to remain undisturbed during the project construction shall be physically marked on the project site. The clearing limits are delineated on the TESC Plan as the area to be disturbed. Cover Measures- Temporary and permanent cover measures shall be provided when necessary to protect disturbed areas. Materials will be stockpiled on-site and will be covered with plastic sheeting per City of Renton SWDM D.2.1.2.4 when necessary. Perimeter Protection- Filter fencing per City of Renton SWDM D.2.1.3.1 shall be used downstream of all disturbed areas to filter sediment from sheet flow. Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 15 Traffic Area Stabilization- A stabilized construction entrance per City of Renton SWDM D.2.1.4.1 shall be implemented. Sediment Retention- Given the small scope of work and minimal grading, the installation of a filter fence will provide adequate means of trapping sediment on-site. If sediment is tracked off-site, public roads shall be cleaned thoroughly at the end of each day or more frequently during wet weather, per CORSWDM Section D.3.2.B.2. Surface Water Collection- Given the small scope of work and minimal grading, runoff can be treated solely with the filter fence used for perimeter protection. There are no significant sources of upstream surface water that drain onto the disturbed areas. Dewatering Control- Dewatering is not anticipated. Dust Control- Dust control is not anticipated to be required but shall be implemented per City of Renton SWDM Table D.2.1.8.A when necessary. Flow Control- Given the scope of the project additional flow control measures are not warranted during construction. Control Pollutants- No pollutants will be stored onsite, but a spill kit shall be retained onsite in case of any fuel spills from construction equipment. Protect Existing and Proposed Flow Control BMPs- The location of the proposed perforated stub out connection shall be protected from compaction/ sedimentation during project construction. Maintain BMPs- TESC BMPs shall be maintained and repaired as needed throughout construction. All disturbed areas of the project site shall be vegetated or otherwise permanently stabilized once completed. Manage the Project- The TESC plan shall be retained onsite anytime construction work is taking place. Prior to commencing construction, a TESC contact will be established. Varma Renton 3 Lot Short Plat Technical Information Report January 29, 2026 Page 16 IX. BOND QUANTITIES, FACILITY SUMMARIES & DECLARATION of COVENANT The Bond Quantities (BQWS) and Declaration of Covenant are included in this section. A Facility Summary is not warranted for this project. Varma Renton 3 Lot Short Plat Technical Information Report Appendix A Wetland and Stream Reconnaissance for 13016- 156th Ave. SE Renton WA by Altmann Oliver Associates, LLC, dated January 29, 2020 January 29, 2020 AOA-6125 Dan Finkbeiner danfinkbeiner@comcast.net SUBJECT: Wetland and Stream Reconnaissance for 13016 – 156th Ave. SE Renton, WA (Parcels 366450-0185 an -0205) Dear Dan: On January 21, 2020 I conducted a wetland and stream reconnaissance on the subject property utilizing the methodology outlined in the May 2010 Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0). No wetlands or streams were identified on or adjacent to the property during the field investigation. The western portion of the site on Parcel 366450-0205 is currently developed with a single-family residence and associated yard. The remainder of this parcel is undeveloped and consisted of a mixed upland forest and brush patches that included Douglas fir (Pseudotsuga menziesii), western red cedar (Thuja plicata), Himalayan blackberry (Rubus armeniacus), English holly (Ilex aquilinum), sword fern (Polystichum munitum), and English ivy (Hedera helix). Parcel 366450-0185 consisted primarily of upland pasture and fill areas. Common plant species were generally typical of disturbed more mesic environments and included a variety of grasses, cats ear (Hypochaeris radicata), English plantain (Plantago lanceolata), and oxeye daisy (Chrysanthemum leucanthemum). No hydrophytic plant communities were observed on or adjacent to the property. Borings taken throughout the site revealed high chroma non-hydric soils and there was no evidence of ponding or prolonged soil saturation anywhere in the vicinity of the property. Dan Finkbeiner January 29, 2020 Page 2 Conclusion No wetlands or streams were identified on or immediately adjacent the site. This determination is based on a field investigation during which no hydrophytic plant communities, hydric soils, or evidence of wetland hydrology or channels were observed. If you have any questions regarding the reconnaissance, please give me a call. Sincerely, ALTMANN OLIVER ASSOCIATES, LLC John Altmann Ecologist Pictometry, King County, King County King County iMap Date: 1/29/2020 Notes: The information included on this map has been compiled by King County staff from a variety of sources and is subject to changewithout notice. King County makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness,or rights to the use of such information. This document is not intended for use as a survey product. King County shall not be liablefor any general, special, indirect, incidental, or consequential damages including, but not limited to, lost revenues or lost profitsresulting from the use or misuse of the information contained on this map. Any sale of this map or information on this map isprohibited except by written permission of King County.± Varma Renton 3 Lot Short Plat Technical Information Report Appendix B Infiltration Assessment by The Riley Group, Inc. dated September 2, 2020 Geotechnical Engineering Report by The Riley Group, Inc. dated November 10, 2022 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone 425.415.0551 ♦ Fax 425.415.0311 www.riley-group.com GEOTECHNICAL ENGINEERING REPORT PREPARED BY: THE RILEY GROUP, INC. 17522 BOTHELL WAY NORTHEAST BOTHELL, WASHINGTON 98011 PREPARED FOR: KUSHAL VARMA 4159 NORTHWEST WOODGATE AVENUE PORTLAND, OREGON 97229 RGI PROJECT NO. 2020-317-1 VARMA 3-LOT SHORT PLAT 13014 156TH AVENUE SOUTHEAST RENTON, WASHINGTON 98059 APRIL 8, 2025 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone 425.415.0551 ♦ Fax 425.415.0311 www.riley-group.com April 8, 2025 Kushal Varma 4159 Northwest Woodgate Avenue Portland, Washington 97229 Subject: Geotechnical Engineering Report Varma 3-Lot Short Plat 13014 156th Avenue Southeast Renton, Washington RGI Project No. 2020-317-1 Dear Mr. Varma: As requested, The Riley Group, Inc. (RGI) has performed a Geotechnical Engineering Report (GER) for the Varma 3-Lot Plat located at 13014 156th Avenue Southeast, Renton, Washington. Our services were completed in accordance with our proposal 2020-317-PRP1 dated August 3, 2020. The information in this GER is based on our understanding of the proposed construction, and the soil and groundwater conditions encountered in the test pits and hand augers completed by RGI at the site on August 24, 2020. RGI recommends that you submit the project plans and specifications to RGI for a general review so that we may confirm that the recommendations in this GER are interpreted and implemented properly in the construction documents. RGI also recommends that a representative of our firm be present on site during portions of the project construction to confirm that the soil and groundwater conditions are consistent with those that form the basis for the engineering recommendations in this GER. If you have any questions or require additional information, please contact us. Respectfully submitted, THE RILEY GROUP, INC. 04/08/2025 Collin McCracken, PE, LG Senior Geotechnical Engineer Geotechnical Engineering Report i April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1 TABLE OF CONTENTS 1.0 INTRODUCTION ............................................................................................................................... 1 2.0 PROJECT DESCRIPTION ............................................................................................................... 1 3.0 FIELD EXPLORATION AND LABORATORY TESTING .......................................................... 1 3.1 FIELD EXPLORATION ................................................................................................................................... 1 3.2 LABORATORY TESTING ................................................................................................................................ 2 4.0 SITE CONDITIONS ........................................................................................................................... 2 4.1 SURFACE .................................................................................................................................................. 2 4.2 GEOLOGY ................................................................................................................................................. 2 4.3 SOILS ....................................................................................................................................................... 2 4.4 GROUNDWATER ........................................................................................................................................ 2 4.5 SEISMIC CONSIDERATIONS ........................................................................................................................... 3 4.6 GEOLOGIC HAZARD AREAS .......................................................................................................................... 4 5.0 DISCUSSION AND RECOMMENDATIONS ................................................................................. 4 5.1 GEOTECHNICAL CONSIDERATIONS ................................................................................................................. 4 5.2 EARTHWORK ............................................................................................................................................. 4 5.2.1 Erosion and Sediment Control ..................................................................................................... 4 5.2.2 Stripping and Subgrade Preparation ............................................................................................ 5 5.2.3 Excavations .................................................................................................................................. 5 5.2.4 Structural Fill ................................................................................................................................ 6 5.2.5 Wet Weather Construction Considerations ................................................................................. 7 5.3 FOUNDATIONS .......................................................................................................................................... 8 5.4 RETAINING WALLS ..................................................................................................................................... 9 5.5 SLAB-ON-GRADE CONSTRUCTION ................................................................................................................. 9 5.6 DRAINAGE .............................................................................................................................................. 10 5.6.1 Surface ....................................................................................................................................... 10 5.6.2 Subsurface .................................................................................................................................. 10 5.6.3 Infiltration .................................................................................................................................. 10 5.7 UTILITIES ................................................................................................................................................ 10 6.0 ADDITIONAL SERVICES .............................................................................................................. 11 7.0 LIMITATIONS ................................................................................................................................. 11 LIST OF FIGURES AND APPENDICES Figure 1 ..................................................................................................................... Site Vicinity Map Figure 2 ............................................................................................... Geotechnical Exploration Plan Figure 3 ............................................................................................... Retaining Wall Drainage Detail Figure 4 ................................................................................................... Typical Footing Drain Detail Appendix A .......................................................................... Field Exploration and Laboratory Testing Geotechnical Engineering Report ii April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1 Executive Summary This Executive Summary should be used in conjunction with the entire Geotechnical Engineering Report (GER) for design and/or construction purposes. It should be recognized that specific details were not included or fully developed in this section, and the GER must be read in its entirety for a comprehensive understanding of the items contained herein. Section 7.0 should be read for an understanding of limitations. RGI’s geotechnical scope of work included the advancement of 2 test pits to approximate depths of 4.5 feet below existing site grades. Based on the information obtained from our subsurface exploration, the site is suitable for development of the proposed project. The following geotechnical considerations were identified: Soil Conditions: The soils encountered during field exploration include medium dense silty sand with gravel over very dense glacial till. Groundwater: No groundwater seepage was encountered during our subsurface exploration. Foundations: Foundations for the proposed residences may be supported on conventional spread footings bearing on medium dense to dense native soil or structural fill. Slab-on-grade: Slab-on-grade floors and slabs for the proposed residences can be supported on medium dense to dense native soil or structural fill. Geotechnical Engineering Report 1 April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1 1.0 Introduction This Geotechnical Engineering Report (GER) presents the results of the geotechnical engineering services provided for the Varma 3-Lot Plat in Renton, Washington. The purpose of this evaluation is to assess subsurface conditions and provide geotechnical recommendations for the construction of a 3-Lot Plat. Our scope of services included field explorations, laboratory testing, engineering analyses, and preparation of this GER. The recommendations in the following sections of this GER are based upon our current understanding of the proposed site development as outlined below. If actual features vary or changes are made, RGI should review them in order to modify our recommendations as required. In addition, RGI requests to review the site grading plan, final design drawings and specifications when available to verify that our project understanding is correct and that our recommendations have been properly interpreted and incorporated into the project design and construction. 2.0 Project description The project site is located at 13014 156th Avenue Southeast in Renton, Washington. The approximate location of the site is shown on Figure 1. The site is currently undeveloped. RGI understands that it is proposed to construct a 3-Lot Plat on the site. At the time of preparing this GER, building plans were not available for our review. Based on our experience with similar construction, RGI anticipates that the proposed building will be supported on perimeter walls with bearing loads of two to six kips per linear foot, and a series of columns with a maximum load up to 30 kips. Slab-on-grade floor loading of 250 pounds per square foot (psf) are expected. 3.0 Field Exploration and Laboratory Testing 3.1 FIELD EXPLORATION On August 24, 2020, RGI observed the excavation of 2 test pits. The approximate exploration locations are shown on Figure 2. Field logs of each exploration were prepared by the geologist that continuously observed the excavations. These logs included visual classifications of the materials encountered during excavation as well as our interpretation of the subsurface conditions between samples. The test pits and hand augers logs included in Appendix A represent an interpretation of the field logs and include modifications based on laboratory observation and analysis of the samples. Geotechnical Engineering Report 2 April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1 3.2 LABORATORY TESTING During the field exploration, a representative portion of each recovered sample was sealed in containers and transported to our laboratory for further visual and laboratory examination. Selected samples retrieved from the test pits were tested for moisture content and grain size analysis to aid in soil classification and provide input for the recommendations provided in this GER. The results and descriptions of the laboratory tests are enclosed in Appendix A. 4.0 Site Conditions 4.1 SURFACE The subject site consists of King County Tax Parcel number 3664500185, and is 1.07 acres in size. The site is bounded to the north, south, and east by residential properties, and to the west by 156th Avenue Southeast. The existing site is undeveloped land covered by scattered trees and other vegetation. The site is relatively flat with an overall elevation difference of approximately 5 feet. 4.2 GEOLOGY Review of the Geologic map of the Renton quadrangle, King County, Washington by Mullineaux, 1965 indicates that the soil in the project vicinity is mapped as Vashon-age lodgment till (Qvt). Lodgment till consists of a non-sorted mixture of silt, sand, gravel, cobbles, and boulders which looks like concrete mix. Till is very dense from compaction of glacial ice and is considered a restrictive layer in stormwater planning. Drainage does occur in the upper several feet of the till deposits, but water ponds and moves laterally along the underlying unweathered till surface. These descriptions are generally similar to our observations in the field. 4.3 SOILS The soils encountered during field exploration include medium dense silty sand with gravel over very dense glacial till. More detailed descriptions of the subsurface conditions encountered are presented in the test pits and hand augers included in Appendix A. Sieve analysis was performed on two selected soil samples. Grain size distribution curves are included in Appendix A. 4.4 GROUNDWATER No groundwater seepage was encountered during our subsurface exploration. Evidence of high groundwater (mottling) was observed in the silty sand overlying the lodgment till in some of the explorations. Geotechnical Engineering Report 3 April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1 It should be recognized that fluctuations of the groundwater table will occur due to seasonal variations in the amount of rainfall, runoff, and other factors not evident at the time the explorations were performed. In addition, perched water can develop within seams and layers contained in fill soils or higher permeability soils overlying less permeable soils following periods of heavy or prolonged precipitation. Therefore, groundwater levels during construction or at other times in the future may be higher or lower than the levels indicated on the logs. 4.5 SEISMIC CONSIDERATIONS Based on the International Building Code (IBC), RGI recommends the follow seismic parameters for design. Table 1 IBC Parameter Value Site Soil Class1 C2 Short Period Spectral Response Acceleration, SS (g) 1.372 1-Second Period Spectral Response Acceleration, S1 (g) 0.470 1. Note: In general accordance with Chapter 20 of ASCE 7-16. The Site Class is based on the average characteristics of the upper 100 feet of the subsurface profile. 2. Note: ASCE 7-16 require a site soil profile determination extending to a depth of 100 feet for seismic site classification. The current scope of our services does not include the required 100 foot soil profile determination. Hand augers extended to a maximum depth of 4 feet, and this seismic site class definition considers that similar soil continues below the maximum depth of the subsurface exploration. Additional exploration to deeper depths would be required to confirm the conditions below the current depth of exploration. 3. Note: In accordance with ASCE 11.4.8, a ground motion hazard analysis is not required for the following cases: • Structures on Site Class E sites with SS greater than or equal to 1.0, provided the site coefficient Fa is taken as equal to that of Site Class C. • Structures on Site Class D sites with S1 greater than or equal to 0.2, provided that the value of the seismic response coefficient Cs is determined by Eq. 12.8-2 for values of T ≤ 1.5Ts and taken as equal to 1.5 times the value computed in accordance with either Eq. 12.8-3 for TL ≥ T > 1.5Ts or Eq. 12.8-4 for T > TL. • Structures on Site Class E sites with S1 greater than or equal to 0.2, provided that T is less than or equal to Ts and the equivalent static force procedure is used for design. The above exceptions do not apply to seismically isolated structures, structures with damping systems or structures designed using the response history procedures of Chapter 16. Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase in water pressure induced by vibrations from a seismic event. Liquefaction mainly affects geologically recent deposits of fine-grained sands that are below the groundwater table. Soils of this nature derive their strength from intergranular friction. The generated water pressure or pore pressure essentially separates the soil grains and eliminates this intergranular friction, thus reducing or eliminating the soil’s strength. RGI reviewed the results of the field and laboratory testing and assessed the potential for liquefaction of the site’s soil during an earthquake. Since the site is underlain by glacial till, RGI considers that the possibility of liquefaction during an earthquake is minimal. Geotechnical Engineering Report 4 April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1 4.6 GEOLOGIC HAZARD AREAS Regulated geologically hazardous areas include erosion, landslide, earthquake, or other geological hazards. Based on the definition in the Renton Municipal Code, the site does not contain geologically hazardous areas. 5.0 Discussion and Recommendations 5.1 GEOTECHNICAL CONSIDERATIONS Based on our study, the site is suitable for the proposed construction from a geotechnical standpoint. Foundations for the proposed residences can be supported on conventional spread footings bearing on competent native soil or structural fill. Slab-on-grade floors can be similarly supported. Detailed recommendations regarding the above issues and other geotechnical design considerations are provided in the following sections. These recommendations should be incorporated into the final design drawings and construction specifications. 5.2 EARTHWORK The earthwork is expected to include excavating and backfilling the building foundations and preparing slab subgrades. 5.2.1 EROSION AND SEDIMENT CONTROL Potential sources or causes of erosion and sedimentation depend on construction methods, slope length and gradient, amount of soil exposed and/or disturbed, soil type, construction sequencing and weather. The impacts on erosion-prone areas can be reduced by implementing an erosion and sedimentation control plan. The plan should be designed in accordance with applicable city and/or county standards. RGI recommends the following erosion control Best Management Practices (BMPs):  Scheduling site preparation and grading for the drier summer and early fall months and undertaking activities that expose soil during periods of little or no rainfall  Retaining existing vegetation whenever feasible  Establishing a quarry spall construction entrance  Installing siltation control fencing or anchored straw or coir wattles on the downhill side of work areas  Covering soil stockpiles with anchored plastic sheeting  Revegetating or mulching exposed soils with a minimum 3-inch thickness of straw if surfaces will be left undisturbed for more than one day during wet weather or one week in dry weather  Directing runoff away from exposed soils and slopes Geotechnical Engineering Report 5 April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1  Minimizing the length and steepness of slopes with exposed soils and cover excavation surfaces with anchored plastic sheeting  Decreasing runoff velocities with check dams, straw bales or coir wattles  Confining sediment to the project site  Inspecting and maintaining erosion and sediment control measures frequently (The contractor should be aware that inspection and maintenance of erosion control BMPs is critical toward their satisfactory performance. Repair and/or replacement of dysfunctional erosion control elements should be anticipated.) Permanent erosion protection should be provided by reestablishing vegetation using hydroseeding and/or landscape planting. Until the permanent erosion protection is established, site monitoring should be performed by qualified personnel to evaluate the effectiveness of the erosion control measures. Provisions for modifications to the erosion control system based on monitoring observations should be included in the erosion and sedimentation control plan. 5.2.2 STRIPPING AND SUBGRADE PREPARATION Stripping efforts should include removal of pavements, vegetation, organic materials, and deleterious debris from areas slated for building, pavement, and utility construction. Minimal ground cover/mulch was observed in the test pit and hand auger locations, however, deeper areas of stripping may be required in forested or heavily vegetated areas of the site. Subgrade soils that become disturbed due to elevated moisture conditions should be overexcavated to reveal firm, non-yielding, non-organic soils and backfilled with compacted structural fill. In order to maximize utilization of site soils as structural fill, RGI recommends that the earthwork portion of this project be completed during extended periods of warm and dry weather if possible. If earthwork is completed during the wet season (typically November through May) it will be necessary to take extra precautionary measures to protect subgrade soils. Wet season earthwork will require additional mitigative measures beyond that which would be expected during the drier summer and fall months. 5.2.3 EXCAVATIONS All temporary cut slopes associated with the site and utility excavations should be adequately inclined to prevent sloughing and collapse. The site soils consist of medium dense silty sand with gravel over very dense glacial till. Accordingly, for excavations more than 4 feet but less than 20 feet in depth, the temporary side slopes should be laid back with a minimum slope inclination of 1H:1V (Horizontal:Vertical). For open cuts at the site, RGI recommends: Geotechnical Engineering Report 6 April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1  No traffic, construction equipment, stockpiles or building supplies are allowed at the top of cut slopes within a distance of at least five feet from the top of the cut  Exposed soil along the slope is protected from surface erosion using waterproof tarps and/or plastic sheeting  Construction activities are scheduled so that the length of time the temporary cut is left open is minimized  Surface water is diverted away from the excavation  The general condition of slopes should be observed periodically by a geotechnical engineer to confirm adequate stability and erosion control measures In all cases, however, appropriate inclinations will depend on the actual soil and groundwater conditions encountered during earthwork. Ultimately, the site contractor must be responsible for maintaining safe excavation slopes that comply with applicable OSHA or WISHA guidelines. 5.2.4 STRUCTURAL FILL RGI recommends fill below the foundation and floor slab, behind retaining walls, and below pavement and hardscape surfaces be placed in accordance with the following recommendations for structural fill. The suitability of excavated site soils and import soils for compacted structural fill use will depend on the gradation and moisture content of the soil when it is placed. As the amount of fines (that portion passing the U.S. No. 200 sieve) increases, soil becomes increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult or impossible to achieve. Soils containing more than about 5 percent fines cannot be consistently compacted to a dense, non-yielding condition when the moisture content is more than 2 percent above or below optimum. Optimum moisture content is that moisture that results in the greatest compacted dry density with a specified compactive effort. Non-organic site soils are only considered suitable for structural fill provided that their moisture content is within about two percent of the optimum moisture level as determined by American Society of Testing and Materials D1557-09 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (ASTM D1557). Excavated site soils may not be suitable for re-use as structural fill depending on the moisture content and weather conditions at the time of construction. If soils are stockpiled for future reuse and wet weather is anticipated, the stockpile should be protected with plastic sheeting that is securely anchored. Even during dry weather, moisture conditioning (such as, windrowing and drying) of site soils to be reused as structural fill may be required. Geotechnical Engineering Report 7 April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1 The site soils are moisture sensitive and may require moisture conditioning prior to use as structural fill. If on-site soils are or become unusable, it may become necessary to import clean, granular soils to complete site work that meet the grading requirements listed in Table 2 to be used as structural fill. Table 2 Structural Fill Gradation U.S. Sieve Size Percent Passing 4 inches 100 No. 4 sieve 22 to 100 No. 200 sieve 0 to 5* *Based on minus 3/4 inch fraction. Prior to use, an RGI representative should observe and test all materials imported to the site for use as structural fill. Structural fill materials should be placed in uniform loose layers not exceeding 12 inches and compacted as specified in Table 3. The soil’s maximum density and optimum moisture should be determined by ASTM D1557. Table 3 Structural Fill Compaction ASTM D1557 Location Material Type Minimum Compaction Percentage Moisture Content Range Foundations On-site granular or approved imported fill soils: 95 +2 -2 Retaining Wall Backfill On-site granular or approved imported fill soils: 92 +2 -2 Slab-on-grade On-site granular or approved imported fill soils: 95 +2 -2 General Fill (non- structural areas) On-site soils or approved imported fill soils: 90 +3 -2 Placement and compaction of structural fill should be observed by RGI. A representative number of in-place density tests should be performed as the fill is being placed to confirm that the recommended level of compaction is achieved. 5.2.5 WET WEATHER CONSTRUCTION CONSIDERATIONS RGI recommends that preparation for site grading and construction include procedures intended to drain ponded water, control surface water runoff, and to collect shallow Geotechnical Engineering Report 8 April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1 subsurface seepage zones in excavations where encountered. It will not be possible to successfully compact the subgrade or utilize on-site soils as structural fill if accumulated water is not drained prior to grading or if drainage is not controlled during construction. Attempting to grade the site without adequate drainage control measures will reduce the amount of on-site soil effectively available for use, increase the amount of select import fill materials required, and ultimately increase the cost of the earthwork phases of the project. Free water should not be allowed to pond on the subgrade soils. RGI anticipates that the use of berms and shallow drainage ditches, with sumps and pumps in utility trenches, will be required for surface water control during wet weather and/or wet site conditions. 5.3 FOUNDATIONS Following site preparation and grading, the proposed building foundation can be supported on conventional spread footings bearing on competent native soil or structural fill. Loose, organic, or other unsuitable soils may be encountered in the proposed building footprint. If unsuitable soils are encountered, they should be overexcavated and backfilled with structural fill. If loose soils are encountered, the soils should be moisture conditioned and compacted to a firm and unyielding condition. The foundation design value assumes the foundation is supported on at least two feet of medium dense native soil or structural fill. Table 4 Foundation Design Design Parameter Value Allowable Bearing Capacity 2,000 psf1 Friction Coefficient 0.30 Passive pressure (equivalent fluid pressure) 250 pcf2 Minimum foundation dimensions Columns: 24 inches Walls: 16 inches 1. psf = pounds per square foot 2. pcf = pounds per cubic foot The allowable foundation bearing pressures apply to dead loads plus design live load conditions. For short-term loads, such as wind and seismic, a 1/3 increase in this allowable capacity may be used. At perimeter locations, RGI recommends not including the upper 12 inches of soil in the computation of passive pressures because they can be affected by weather or disturbed by future grading activity. The passive pressure value assumes the foundation will be constructed neat against competent soil or backfilled with structural fill as described in Section 5.2.4. The recommended base friction and passive resistance value includes a safety factor of about 1.5. Geotechnical Engineering Report 9 April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1 Perimeter foundations exposed to weather should be at a minimum depth of 18 inches below final exterior grades. Interior foundations can be constructed at any convenient depth below the floor slab. Finished grade is defined as the lowest adjacent grade within 5 feet of the foundation for perimeter (or exterior) footings and finished floor level for interior footings. With spread footing foundations designed in accordance with the recommendations in this section, maximum total and differential post-construction settlements of 1 inch and 1/2 inch, respectively, should be expected. 5.4 RETAINING WALLS If retaining walls are needed in the building area, RGI recommends cast-in-place concrete walls be used. The magnitude of earth pressure development on retaining walls will partly depend on the quality of the wall backfill. RGI recommends placing and compacting wall backfill as structural fill. Wall drainage will be needed behind the wall face. A typical retaining wall drainage detail is shown in Figure 3. With wall backfill placed and compacted as recommended, and drainage properly installed, RGI recommends using the values in the following table for design. Table 5 Retaining Wall Design Design Parameter Value Allowable Bearing Capacity 2,000 psf Active Earth Pressure (unrestrained walls) 35 pcf At-rest Earth Pressure (restrained walls) 50 pcf For seismic design, an additional uniform load of 7 times the wall height (H) for unrestrained walls and 14H in psf for restrained walls should be applied to the wall surface. Friction at the base of foundations and passive earth pressure will provide resistance to these lateral loads. Values for these parameters are provided in Section 5.3. 5.5 SLAB-ON-GRADE CONSTRUCTION Once site preparation has been completed as described in Section 5.2, suitable support for slab-on-grade construction should be provided. RGI recommends that the concrete slab be placed on top of medium dense native soil or structural fill. Immediately below the floor slab, RGI recommends placing a four-inch thick capillary break layer of clean, free-draining sand or gravel that has less than five percent passing the U.S. No. 200 sieve. This material will reduce the potential for upward capillary movement of water through the underlying soil and subsequent wetting of the floor slab. Where moisture by vapor transmission is Geotechnical Engineering Report 10 April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1 undesirable, an 8- to 10-millimeter thick plastic membrane should be placed on a 4-inch thick layer of clean gravel. For the anticipated floor slab loading, we estimate post-construction floor settlements of 1/4- to 1/2-inch. 5.6 DRAINAGE 5.6.1 SURFACE Final exterior grades should promote free and positive drainage away from the building area. Water must not be allowed to pond or collect adjacent to foundations or within the immediate building area. For non-pavement locations, RGI recommends providing a minimum drainage gradient of 3 percent for a minimum distance of 10 feet from the building perimeter. In paved locations, a minimum gradient of 1 percent should be provided unless provisions are included for collection and disposal of surface water adjacent to the structure. 5.6.2 SUBSURFACE RGI recommends installing perimeter foundation drains. A typical footing drain detail is shown on Figure 4. The foundation drains and roof downspouts should be tightlined separately to an approved discharge facility. Subsurface drains must be laid with a gradient sufficient to promote positive flow to a controlled point of approved discharge. 5.6.3 INFILTRATION The site is underlain by very dense glacial till, commonly referred to as “hardpan.” This material does not allow for infiltration. 5.7 UTILITIES Utility pipes should be bedded and backfilled in accordance with American Public Works Association (APWA) specifications. For site utilities located within the right-of-ways, bedding and backfill should be completed in accordance with City of Renton specifications. At a minimum, trench backfill should be placed and compacted as structural fill, as described in Section 5.2.4. Where utilities occur below unimproved areas, the degree of compaction can be reduced to a minimum of 90 percent of the soil’s maximum density as determined by the referenced ASTM D1557. As noted, soils excavated on site will not be suitable for use as backfill material. Imported structural fill meeting the gradation provided in Table 2 should be used for trench backfill. Geotechnical Engineering Report 11 April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1 6.0 Additional Services RGI is available to provide further geotechnical consultation throughout the design phase of the project. RGI should review the final design and specifications in order to verify that earthwork and foundation recommendations have been properly interpreted and incorporated into project design and construction. RGI is also available to provide geotechnical engineering and construction monitoring services during construction. The integrity of the earthwork and construction depends on proper site preparation and procedures. In addition, engineering decisions may arise in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this scope of work. If these services are desired, please let us know and we will prepare a cost proposal. 7.0 Limitations This GER is the property of RGI, Kushal Varma, and its designated agents. Within the limits of the scope and budget, this GER was prepared in accordance with generally accepted geotechnical engineering practices in the area at the time this GER was issued. This GER is intended for specific application to the proposed Varma 3-Lot Plat in Renton, Washington, and for the exclusive use of Kushal Varma and its authorized representatives. No other warranty, expressed or implied, is made. Site safety, excavation support, and dewatering requirements are the responsibility of others. The scope of services for this project does not include either specifically or by implication any environmental or biological (for example, mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, we can provide a proposal for these services. The analyses and recommendations presented in this GER are based upon data obtained from the explorations performed on site. Variations in soil conditions can occur, the nature and extent of which may not become evident until construction. If variations appear evident, RGI should be requested to reevaluate the recommendations in this GER prior to proceeding with construction. It is the client’s responsibility to see that all parties to the project, including the designers, contractors, subcontractors, are made aware of this GER in its entirety. The use of information contained in this GER for bidding purposes should be done at the contractor’s option and risk. USGS, 2020, Renton, Washington USGS, 2020, Maple Valley, Washington 7.5-Minute Quadrangle Approximate Scale: 1"=1000' 0 500 1000 2000 N Site Vicinity Map Figure 1 04/2025 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone: 425.415.0551 Fax: 425.415.0311 Varma 3-Lot Short Plat RGI Project Number: 2020-317-1 Date Drawn: Address: 13011 156th Avenue Southeast, Renton, Washington 98059 SITE TP-4 TP-3 04/2025 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone: 425.415.0551 Fax: 425.415.0311 Varma 3-Lot Short Plat RGI Project Number: 2020-317-1 Date Drawn: Address: 13011 156th Avenue Southeast, Renton, Washington 98059 Figure 2 Approximate Scale: 1"=50' 0 25 50 100 N = Test pit locations by RGI, 08/24/2020 = Site boundary Geotechnical Exploration Plan Incliniations) 12" Over the Pipe 3" Below the Pipe Perforated Pipe 4" Diameter PVC Compacted Structural Backfill (Native or Import) 12" min. Filter Fabric Material 12" Minimum Wide Free-Draining Gravel Slope to Drain (See Report for Appropriate Excavated Slope 04/2025 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone: 425.415.0551 Fax: 425.415.0311 Varma 3-Lot Short Plat RGI Project Number: 2020-317-1 Date Drawn: Address: 13011 156th Avenue Southeast, Renton, Washington 98059 Retaining Wall Drainage Detail Figure 3 Not to Scale Building Slab Structural Backfill Compacted 04/2025 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone: 425.415.0551 Fax: 425.415.0311 Varma 3-Lot Short Plat RGI Project Number: 2020-317-1 Date Drawn: Address: 13011 156th Avenue Southeast, Renton, Washington 98059 Typical Foundation Drainage Detail Figure 4 Not to Scale Gravel or Crushed Stone with less than 10% passing No. 4 (4.75mm) Sieve 12" Minimum 4" Perforated Pipe (See Report Text) Approved Filter Membrane Material Geotechnical Engineering Report April 8, 2025 Varma 3-Lot Short Plat, Renton, Washington RGI Project No. 2020-317-1 APPENDIX A FIELD EXPLORATION AND LABORATORY TESTING On August 24, 2020, RGI performed field explorations using a trackhoe. We explored subsurface soil conditions at the site by observing the excavation of two test pits. The test pit locations are shown on Figure 2. The test pit locations were approximately determined by measurements from existing property lines and paved roads. A geologist from our office conducted the field exploration and classified the soil conditions encountered, maintained a log of each test exploration, obtained representative soil samples, and observed pertinent site features. All soil samples were visually classified in accordance with the Unified Soil Classification System (USCS). Representative soil samples obtained from the explorations were placed in closed containers and taken to our laboratory for further examination and testing. As a part of the laboratory testing program, the soil samples were classified in our in house laboratory based on visual observation, texture, plasticity, and the limited laboratory testing described below. Moisture Content Determinations Moisture content determinations were performed in accordance with ASTM D2216-10 Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass (ASTM D2216) on representative samples obtained from the exploration in order to aid in identification and correlation of soil types. The moisture content of typical sample was measured and is reported on the test pit logs. Grain Size Analysis A grain size analysis indicates the range in diameter of soil particles included in a particular sample. Grain size analyses was determined using D6913-04(2009) Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis (ASTM D6913) on two of the samples. Project Name: Varma 3-Lot Short Plat Project Number: 2020-317-1 Client: Kushal Varma Test Pit No.: TP-3 Date(s) Excavated:08/24/20 Excavation Method: Excavator Type: Groundwater Level:Not encountered Test Pit Backfill:Native Soil Logged By LC Bucket Size:n/a Excavating Contractor:Client Provided Sampling Method(s)Grab Location 13014 156th Avenue Southeast, Renton, Washington 98059 Surface Conditions:Mulch Total Depth of Excavation:4.5 feet bgs Approximate Surface Elevation n/a Compaction Method n/a US C S S y m b o l SM SM REMARKS AND OTHER TESTSGr a p h i c L o g MATERIAL DESCRIPTION Brown, silty SAND with some gravel, medium dense, moist Gray, silty SAND with gravel (till), very dense, moist Test pit excavated to 4.5 feet bgs No groundwater encountered De p t h ( f e e t ) 0 5 10 Sa m p l e N u m b e r Sa m p l e T y p e El e v a t i o n ( f e e t ) Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name: Varma 3-Lot Short Plat Project Number: 2020-317-1 Client: Kushal Varma Test Pit No.: TP-4 Date(s) Excavated:08/24/20 Excavation Method: Excavator Type: Groundwater Level:Not encountered Test Pit Backfill:Native Soil Logged By LC Bucket Size:n/a Excavating Contractor:Client Provided Sampling Method(s)Grab Location 13014 156th Avenue Southeast, Renton, Washington 98059 Surface Conditions:Mulch Total Depth of Excavation:4.5 feet bgs Approximate Surface Elevation n/a Compaction Method n/a US C S S y m b o l SM SM REMARKS AND OTHER TESTSGr a p h i c L o g MATERIAL DESCRIPTION Brown, silty SAND with gravel, medium dense, moist Gray, silty SAND with gravel (till), very dense, moist Test pit excavated to 4.5 feet bgs No groundwater encountered De p t h ( f e e t ) 0 5 10 Sa m p l e N u m b e r Sa m p l e T y p e El e v a t i o n ( f e e t ) Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name: Varma 3-Lot Short Plat Project Number: 2020-317-1 Client: Kushal Varma Key to Logs US C S S y m b o l REMARKS AND OTHER TESTSGr a p h i c L o g MATERIAL DESCRIPTIONDe p t h ( f e e t ) Sa m p l e N u m b e r Sa m p l e T y p e El e v a t i o n ( f e e t ) 1 2 3 4 5 6 7 8 COLUMN DESCRIPTIONS 1 Elevation (feet): Elevation (MSL, feet). 2 Depth (feet): Depth in feet below the ground surface. 3 Sample Type: Type of soil sample collected at the depth interval shown. 4 Sample Number: Sample identification number. 5 USCS Symbol: USCS symbol of the subsurface material. 6 Graphic Log: Graphic depiction of the subsurface material encountered. 7 MATERIAL DESCRIPTION: Description of material encountered. May include consistency, moisture, color, and other descriptive text. 8 REMARKS AND OTHER TESTS: Comments and observations regarding drilling or sampling made by driller or field personnel. FIELD AND LABORATORY TEST ABBREVIATIONS CHEM: Chemical tests to assess corrosivity COMP: Compaction test CONS: One-dimensional consolidation test LL: Liquid Limit, percent PI: Plasticity Index, percent SA: Sieve analysis (percent passing No. 200 Sieve) UC: Unconfined compressive strength test, Qu, in ksf WA: Wash sieve (percent passing No. 200 Sieve) MATERIAL GRAPHIC SYMBOLS Silty SAND (SM) TYPICAL SAMPLER GRAPHIC SYMBOLS Auger sampler Bulk Sample 3-inch-OD California w/ brass rings CME Sampler Grab Sample 2.5-inch-OD Modified California w/ brass liners Pitcher Sample 2-inch-OD unlined split spoon (SPT) Shelby Tube (Thin-walled, fixed head) OTHER GRAPHIC SYMBOLS Water level (at time of drilling, ATD) Water level (after waiting) Minor change in material properties within a stratum Inferred/gradational contact between strata ?Queried contact between strata GENERAL NOTES 1: Soil classifications are based on the Unified Soil Classification System. Descriptions and stratum lines are interpretive, and actual lithologic changes may be gradual. Field descriptions may have been modified to reflect results of lab tests. 2: Descriptions on these logs apply only at the specific boring locations and at the time the borings were advanced. They are not warranted to be representative of subsurface conditions at other locations or times. Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Varma Renton 3 Lot Short Plat Technical Information Report Appendix C WWHM Output WWHM2012 PROJECT REPORT Varma 3-Lot 1/21/2026 3:48:13 PM Page 2 General Model Information WWHM2012 Project Name:Varma 3-Lot Site Name:Varma SFR Site Address: City: Report Date:1/21/2026 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.167 Version Date:2023/01/27 Version:4.2.19 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year Low Flow Threshold for POC2:50 Percent of the 2 Year High Flow Threshold for POC2:50 Year Varma 3-Lot 1/21/2026 3:48:13 PM Page 3 Landuse Basin Data Predeveloped Land Use West Basin Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Flat 0.338 Pervious Total 0.338 Impervious Land Use acre Impervious Total 0 Basin Total 0.338 Varma 3-Lot 1/21/2026 3:48:13 PM Page 4 East Basin Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Flat 0.272 Pervious Total 0.272 Impervious Land Use acre Impervious Total 0 Basin Total 0.272 Varma 3-Lot 1/21/2026 3:48:13 PM Page 5 Mitigated Land Use West Basin Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.249 Pervious Total 0.249 Impervious Land Use acre ROADS FLAT 0.01 ROOF TOPS FLAT 0.064 DRIVEWAYS FLAT 0.01 Impervious Total 0.084 Basin Total 0.333 Varma 3-Lot 1/21/2026 3:48:13 PM Page 6 East Basin Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Steep 0.1814 Pervious Total 0.1814 Impervious Land Use acre ROADS FLAT 0.013 ROOF TOPS FLAT 0.0661 DRIVEWAYS FLAT 0.0113 Impervious Total 0.0904 Basin Total 0.2718 Varma 3-Lot 1/21/2026 3:48:13 PM Page 7 Routing Elements Predeveloped Routing Varma 3-Lot 1/21/2026 3:48:13 PM Page 8 Mitigated Routing Varma 3-Lot 1/21/2026 3:48:13 PM Page 9 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.338 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.249 Total Impervious Area:0.084 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.013204 5 year 0.021769 10 year 0.028271 25 year 0.037357 50 year 0.044726 100 year 0.052589 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.068662 5 year 0.099606 10 year 0.12199 25 year 0.152387 50 year 0.176558 100 year 0.202033 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.016 0.109 1950 0.019 0.106 1951 0.027 0.066 1952 0.009 0.038 1953 0.008 0.036 1954 0.011 0.057 1955 0.017 0.058 1956 0.014 0.056 1957 0.013 0.079 1958 0.013 0.048 Varma 3-Lot 1/21/2026 3:48:48 PM Page 10 1959 0.011 0.036 1960 0.021 0.067 1961 0.011 0.063 1962 0.007 0.038 1963 0.010 0.065 1964 0.013 0.054 1965 0.010 0.082 1966 0.009 0.045 1967 0.020 0.106 1968 0.012 0.093 1969 0.011 0.079 1970 0.010 0.065 1971 0.012 0.075 1972 0.021 0.107 1973 0.010 0.035 1974 0.011 0.075 1975 0.016 0.080 1976 0.011 0.056 1977 0.004 0.061 1978 0.009 0.065 1979 0.006 0.070 1980 0.030 0.121 1981 0.009 0.070 1982 0.021 0.124 1983 0.014 0.066 1984 0.009 0.050 1985 0.005 0.069 1986 0.022 0.063 1987 0.020 0.077 1988 0.009 0.032 1989 0.005 0.044 1990 0.057 0.193 1991 0.025 0.143 1992 0.011 0.049 1993 0.010 0.036 1994 0.004 0.029 1995 0.014 0.054 1996 0.032 0.089 1997 0.025 0.075 1998 0.009 0.058 1999 0.035 0.161 2000 0.010 0.071 2001 0.003 0.058 2002 0.014 0.108 2003 0.019 0.086 2004 0.022 0.145 2005 0.014 0.064 2006 0.015 0.061 2007 0.042 0.177 2008 0.044 0.140 2009 0.020 0.084 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0566 0.1931 2 0.0444 0.1769 3 0.0418 0.1606 Varma 3-Lot 1/21/2026 3:48:48 PM Page 11 4 0.0352 0.1449 5 0.0322 0.1429 6 0.0295 0.1403 7 0.0271 0.1242 8 0.0255 0.1210 9 0.0255 0.1094 10 0.0221 0.1075 11 0.0218 0.1074 12 0.0211 0.1062 13 0.0207 0.1058 14 0.0205 0.0928 15 0.0203 0.0890 16 0.0201 0.0858 17 0.0200 0.0838 18 0.0189 0.0818 19 0.0188 0.0800 20 0.0171 0.0794 21 0.0162 0.0792 22 0.0157 0.0774 23 0.0148 0.0755 24 0.0143 0.0752 25 0.0141 0.0745 26 0.0140 0.0713 27 0.0137 0.0699 28 0.0137 0.0696 29 0.0129 0.0692 30 0.0128 0.0666 31 0.0126 0.0663 32 0.0120 0.0660 33 0.0117 0.0652 34 0.0113 0.0650 35 0.0112 0.0646 36 0.0111 0.0642 37 0.0110 0.0634 38 0.0109 0.0626 39 0.0106 0.0611 40 0.0105 0.0607 41 0.0103 0.0585 42 0.0103 0.0583 43 0.0098 0.0578 44 0.0098 0.0571 45 0.0096 0.0561 46 0.0095 0.0560 47 0.0094 0.0539 48 0.0091 0.0539 49 0.0091 0.0499 50 0.0089 0.0493 51 0.0087 0.0476 52 0.0086 0.0449 53 0.0086 0.0439 54 0.0077 0.0384 55 0.0071 0.0379 56 0.0058 0.0364 57 0.0055 0.0360 58 0.0052 0.0359 59 0.0042 0.0353 60 0.0039 0.0323 61 0.0026 0.0288 Varma 3-Lot 1/21/2026 3:48:48 PM Page 12 Varma 3-Lot 1/21/2026 3:48:48 PM Page 13 Duration Flows The Duration Matching Failed Flow(cfs)Predev Mit Percentage Pass/Fail 0.0066 18444 69236 375 Fail 0.0070 16091 62926 391 Fail 0.0074 14316 57129 399 Fail 0.0078 12690 52060 410 Fail 0.0081 11176 47633 426 Fail 0.0085 9882 43612 441 Fail 0.0089 8814 39976 453 Fail 0.0093 7835 36725 468 Fail 0.0097 7005 33709 481 Fail 0.0101 6301 31014 492 Fail 0.0105 5679 28533 502 Fail 0.0108 5180 26330 508 Fail 0.0112 4699 24298 517 Fail 0.0116 4286 22458 523 Fail 0.0120 3908 20783 531 Fail 0.0124 3529 19308 547 Fail 0.0128 3185 17843 560 Fail 0.0131 2868 16611 579 Fail 0.0135 2594 15389 593 Fail 0.0139 2357 14273 605 Fail 0.0143 2141 13287 620 Fail 0.0147 1955 12444 636 Fail 0.0151 1796 11595 645 Fail 0.0155 1671 10825 647 Fail 0.0158 1517 10087 664 Fail 0.0162 1346 9475 703 Fail 0.0166 1223 8861 724 Fail 0.0170 1124 8354 743 Fail 0.0174 1042 7856 753 Fail 0.0178 971 7409 763 Fail 0.0182 910 6941 762 Fail 0.0185 839 6524 777 Fail 0.0189 766 6139 801 Fail 0.0193 704 5781 821 Fail 0.0197 635 5441 856 Fail 0.0201 570 5123 898 Fail 0.0205 488 4836 990 Fail 0.0209 425 4581 1077 Fail 0.0212 376 4350 1156 Fail 0.0216 341 4107 1204 Fail 0.0220 307 3891 1267 Fail 0.0224 270 3683 1364 Fail 0.0228 235 3501 1489 Fail 0.0232 196 3290 1678 Fail 0.0235 171 3114 1821 Fail 0.0239 145 2960 2041 Fail 0.0243 125 2819 2255 Fail 0.0247 107 2680 2504 Fail 0.0251 95 2554 2688 Fail 0.0255 84 2445 2910 Fail 0.0259 71 2353 3314 Fail 0.0262 61 2252 3691 Fail 0.0266 55 2165 3936 Fail 0.0270 45 2066 4591 Fail Varma 3-Lot 1/21/2026 3:48:48 PM Page 14 0.0274 40 1988 4970 Fail 0.0278 37 1898 5129 Fail 0.0282 35 1838 5251 Fail 0.0286 29 1765 6086 Fail 0.0289 25 1693 6772 Fail 0.0293 22 1634 7427 Fail 0.0297 17 1576 9270 Fail 0.0301 15 1518 10120 Fail 0.0305 11 1466 13327 Fail 0.0309 9 1419 15766 Fail 0.0312 8 1369 17112 Fail 0.0316 8 1323 16537 Fail 0.0320 8 1279 15987 Fail 0.0324 7 1225 17500 Fail 0.0328 7 1184 16914 Fail 0.0332 7 1137 16242 Fail 0.0336 7 1099 15700 Fail 0.0339 7 1056 15085 Fail 0.0343 7 1026 14657 Fail 0.0347 7 998 14257 Fail 0.0351 6 964 16066 Fail 0.0355 5 933 18660 Fail 0.0359 5 902 18040 Fail 0.0363 5 880 17600 Fail 0.0366 4 854 21350 Fail 0.0370 4 828 20700 Fail 0.0374 4 798 19950 Fail 0.0378 4 770 19250 Fail 0.0382 4 742 18550 Fail 0.0386 4 728 18200 Fail 0.0389 4 716 17900 Fail 0.0393 4 696 17400 Fail 0.0397 4 676 16900 Fail 0.0401 4 654 16350 Fail 0.0405 3 639 21300 Fail 0.0409 3 621 20700 Fail 0.0413 3 606 20200 Fail 0.0416 3 588 19600 Fail 0.0420 2 569 28450 Fail 0.0424 2 555 27750 Fail 0.0428 2 536 26800 Fail 0.0432 2 525 26250 Fail 0.0436 2 516 25800 Fail 0.0440 2 504 25200 Fail 0.0443 2 492 24600 Fail 0.0447 1 485 48500 Fail The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 50% of the flows for the range of the duration analysis. Varma 3-Lot 1/21/2026 3:48:48 PM Page 15 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. Varma 3-Lot 1/21/2026 3:48:48 PM Page 16 LID Report Varma 3-Lot 1/21/2026 3:49:48 PM Page 17 POC 2 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #2 Total Pervious Area:0.272 Total Impervious Area:0 Mitigated Landuse Totals for POC #2 Total Pervious Area:0.1814 Total Impervious Area:0.0904 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #2 Return Period Flow(cfs) 2 year 0.010626 5 year 0.017518 10 year 0.022751 25 year 0.030063 50 year 0.035993 100 year 0.04232 Flow Frequency Return Periods for Mitigated. POC #2 Return Period Flow(cfs) 2 year 0.073048 5 year 0.102439 10 year 0.122707 25 year 0.149183 50 year 0.169518 100 year 0.19037 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #2 Year Predeveloped Mitigated 1949 0.013 0.116 1950 0.015 0.102 1951 0.022 0.067 1952 0.007 0.042 1953 0.006 0.040 1954 0.009 0.061 1955 0.014 0.062 1956 0.011 0.061 1957 0.010 0.083 1958 0.010 0.054 1959 0.009 0.042 Varma 3-Lot 1/21/2026 3:50:23 PM Page 18 1960 0.017 0.070 1961 0.008 0.063 1962 0.006 0.043 1963 0.008 0.069 1964 0.010 0.057 1965 0.008 0.086 1966 0.007 0.048 1967 0.016 0.103 1968 0.009 0.101 1969 0.009 0.080 1970 0.008 0.071 1971 0.010 0.086 1972 0.017 0.101 1973 0.008 0.039 1974 0.009 0.080 1975 0.013 0.085 1976 0.009 0.061 1977 0.003 0.063 1978 0.008 0.070 1979 0.005 0.078 1980 0.024 0.127 1981 0.007 0.074 1982 0.017 0.121 1983 0.011 0.075 1984 0.007 0.053 1985 0.004 0.075 1986 0.018 0.068 1987 0.016 0.082 1988 0.007 0.035 1989 0.004 0.050 1990 0.046 0.177 1991 0.020 0.138 1992 0.009 0.054 1993 0.008 0.038 1994 0.003 0.032 1995 0.011 0.061 1996 0.026 0.094 1997 0.021 0.075 1998 0.007 0.064 1999 0.028 0.175 2000 0.008 0.077 2001 0.002 0.065 2002 0.011 0.105 2003 0.015 0.093 2004 0.018 0.155 2005 0.012 0.066 2006 0.012 0.062 2007 0.034 0.161 2008 0.036 0.133 2009 0.016 0.086 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #2 Rank Predeveloped Mitigated 1 0.0455 0.1766 2 0.0358 0.1747 3 0.0337 0.1611 4 0.0283 0.1552 Varma 3-Lot 1/21/2026 3:50:23 PM Page 19 5 0.0259 0.1384 6 0.0238 0.1326 7 0.0218 0.1266 8 0.0205 0.1211 9 0.0205 0.1155 10 0.0178 0.1051 11 0.0175 0.1034 12 0.0170 0.1017 13 0.0167 0.1013 14 0.0165 0.1013 15 0.0163 0.0943 16 0.0161 0.0932 17 0.0161 0.0864 18 0.0152 0.0858 19 0.0151 0.0858 20 0.0138 0.0849 21 0.0130 0.0825 22 0.0127 0.0817 23 0.0119 0.0803 24 0.0115 0.0800 25 0.0113 0.0783 26 0.0112 0.0772 27 0.0110 0.0750 28 0.0110 0.0748 29 0.0104 0.0746 30 0.0103 0.0744 31 0.0101 0.0713 32 0.0097 0.0704 33 0.0094 0.0695 34 0.0091 0.0693 35 0.0090 0.0678 36 0.0089 0.0674 37 0.0089 0.0659 38 0.0087 0.0648 39 0.0086 0.0640 40 0.0085 0.0630 41 0.0083 0.0625 42 0.0083 0.0623 43 0.0079 0.0617 44 0.0079 0.0615 45 0.0078 0.0611 46 0.0076 0.0608 47 0.0076 0.0606 48 0.0073 0.0571 49 0.0073 0.0543 50 0.0072 0.0541 51 0.0070 0.0535 52 0.0069 0.0498 53 0.0069 0.0476 54 0.0062 0.0426 55 0.0058 0.0419 56 0.0047 0.0416 57 0.0044 0.0400 58 0.0042 0.0387 59 0.0034 0.0379 60 0.0031 0.0353 61 0.0021 0.0316 Varma 3-Lot 1/21/2026 3:50:23 PM Page 20 Varma 3-Lot 1/21/2026 3:50:23 PM Page 21 Duration Flows The Duration Matching Failed Flow(cfs)Predev Mit Percentage Pass/Fail 0.0053 18444 89320 484 Fail 0.0056 16095 82839 514 Fail 0.0059 14318 77085 538 Fail 0.0062 12694 71695 564 Fail 0.0066 11178 66648 596 Fail 0.0069 9882 62113 628 Fail 0.0072 8812 57964 657 Fail 0.0075 7830 54199 692 Fail 0.0078 7005 50606 722 Fail 0.0081 6288 47312 752 Fail 0.0084 5679 44318 780 Fail 0.0087 5168 41537 803 Fail 0.0090 4697 39099 832 Fail 0.0093 4278 36682 857 Fail 0.0097 3903 34457 882 Fail 0.0100 3525 32361 918 Fail 0.0103 3183 30479 957 Fail 0.0106 2864 28640 1000 Fail 0.0109 2592 27035 1043 Fail 0.0112 2353 25474 1082 Fail 0.0115 2138 23998 1122 Fail 0.0118 1951 22715 1164 Fail 0.0121 1795 21432 1193 Fail 0.0124 1669 20219 1211 Fail 0.0128 1514 19107 1262 Fail 0.0131 1343 18050 1344 Fail 0.0134 1222 17122 1401 Fail 0.0137 1123 16234 1445 Fail 0.0140 1042 15359 1473 Fail 0.0143 969 14583 1504 Fail 0.0146 910 13907 1528 Fail 0.0149 839 13214 1574 Fail 0.0152 766 12527 1635 Fail 0.0155 705 11903 1688 Fail 0.0158 635 11319 1782 Fail 0.0162 572 10739 1877 Fail 0.0165 489 10258 2097 Fail 0.0168 426 9779 2295 Fail 0.0171 378 9334 2469 Fail 0.0174 341 8889 2606 Fail 0.0177 309 8496 2749 Fail 0.0180 271 8143 3004 Fail 0.0183 237 7751 3270 Fail 0.0186 196 7437 3794 Fail 0.0189 171 7116 4161 Fail 0.0193 145 6799 4688 Fail 0.0196 125 6504 5203 Fail 0.0199 109 6198 5686 Fail 0.0202 95 5938 6250 Fail 0.0205 84 5698 6783 Fail 0.0208 71 5450 7676 Fail 0.0211 61 5234 8580 Fail 0.0214 55 5011 9110 Fail 0.0217 45 4815 10700 Fail Varma 3-Lot 1/21/2026 3:50:23 PM Page 22 0.0220 40 4611 11527 Fail 0.0224 37 4408 11913 Fail 0.0227 35 4231 12088 Fail 0.0230 29 4057 13989 Fail 0.0233 25 3893 15572 Fail 0.0236 22 3732 16963 Fail 0.0239 17 3587 21100 Fail 0.0242 15 3439 22926 Fail 0.0245 11 3317 30154 Fail 0.0248 9 3189 35433 Fail 0.0251 8 3065 38312 Fail 0.0255 8 2954 36925 Fail 0.0258 8 2845 35562 Fail 0.0261 7 2744 39200 Fail 0.0264 7 2644 37771 Fail 0.0267 7 2543 36328 Fail 0.0270 7 2458 35114 Fail 0.0273 7 2385 34071 Fail 0.0276 7 2308 32971 Fail 0.0279 7 2237 31957 Fail 0.0282 6 2167 36116 Fail 0.0286 5 2106 42120 Fail 0.0289 5 2045 40900 Fail 0.0292 5 1982 39640 Fail 0.0295 4 1911 47775 Fail 0.0298 4 1857 46425 Fail 0.0301 4 1805 45125 Fail 0.0304 4 1758 43950 Fail 0.0307 4 1699 42475 Fail 0.0310 4 1654 41350 Fail 0.0313 4 1608 40200 Fail 0.0317 4 1560 39000 Fail 0.0320 4 1523 38075 Fail 0.0323 4 1477 36925 Fail 0.0326 3 1444 48133 Fail 0.0329 3 1398 46600 Fail 0.0332 3 1367 45566 Fail 0.0335 3 1335 44500 Fail 0.0338 2 1302 65100 Fail 0.0341 2 1265 63250 Fail 0.0344 2 1217 60850 Fail 0.0348 2 1185 59250 Fail 0.0351 2 1162 58100 Fail 0.0354 2 1126 56300 Fail 0.0357 2 1096 54800 Fail 0.0360 1 1065 106500 Fail The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 50% of the flows for the range of the duration analysis. Varma 3-Lot 1/21/2026 3:50:23 PM Page 23 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. Varma 3-Lot 1/21/2026 3:50:23 PM Page 24 LID Report Varma 3-Lot 1/21/2026 3:50:23 PM Page 25 POC 3 POC #3 was not reported because POC must exist in both scenarios and both scenarios must have been run. Varma 3-Lot 1/21/2026 3:50:23 PM Page 26 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. Varma 3-Lot 1/21/2026 3:50:23 PM Page 27 Appendix Predeveloped Schematic Varma 3-Lot 1/21/2026 3:50:25 PM Page 28 Mitigated Schematic Varma 3-Lot 1/21/2026 3:50:27 PM Page 29 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 Varma 3-Lot.wdm MESSU 25 PreVarma 3-Lot.MES 27 PreVarma 3-Lot.L61 28 PreVarma 3-Lot.L62 30 POCVarma 3-Lot1.dat 31 POCVarma 3-Lot2.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 10 COPY 501 COPY 502 DISPLY 1 DISPLY 2 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 West Basin MAX 1 2 30 9 2 East Basin MAX 1 2 31 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 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 *** 10 C, Forest, Flat 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 10 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO Varma 3-Lot 1/21/2026 3:50:27 PM Page 30 <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 10 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 10 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 10 0 4.5 0.08 400 0.05 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 10 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 10 0.2 0.5 0.35 6 0.5 0.7 END PWAT-PARM4 PWAT-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 10 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 *** END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END IWAT-PARM3 Varma 3-Lot 1/21/2026 3:50:27 PM Page 31 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** West Basin *** PERLND 10 0.338 COPY 501 12 PERLND 10 0.338 COPY 501 13 East Basin*** PERLND 10 0.272 COPY 502 12 PERLND 10 0.272 COPY 502 13 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 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 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 Varma 3-Lot 1/21/2026 3:50:27 PM Page 32 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 1.167 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1.167 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 END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 END MASS-LINK END RUN Varma 3-Lot 1/21/2026 3:50:27 PM Page 33 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 Varma 3-Lot.wdm MESSU 25 MitVarma 3-Lot.MES 27 MitVarma 3-Lot.L61 28 MitVarma 3-Lot.L62 30 POCVarma 3-Lot1.dat 31 POCVarma 3-Lot2.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 16 IMPLND 1 IMPLND 4 IMPLND 5 PERLND 18 COPY 501 COPY 502 DISPLY 1 DISPLY 2 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 West Basin MAX 1 2 30 9 2 East Basin MAX 1 2 31 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 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 18 C, Lawn, Steep 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** Varma 3-Lot 1/21/2026 3:50:27 PM Page 34 # - # 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 18 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 18 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 18 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 18 0 4.5 0.03 400 0.15 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 18 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 18 0.1 0.15 0.25 6 0.3 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 18 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 4 ROOF TOPS/FLAT 1 1 1 27 0 5 DRIVEWAYS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 4 0 0 1 0 0 0 5 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR Varma 3-Lot 1/21/2026 3:50:27 PM Page 35 # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 4 1 9 4 0 0 4 0 0 0 1 9 5 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 4 0 0 0 0 0 5 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 4 400 0.01 0.1 0.1 5 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 4 0 0 5 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 4 0 0 5 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** West Basin*** PERLND 16 0.249 COPY 501 12 PERLND 16 0.249 COPY 501 13 IMPLND 1 0.01 COPY 501 15 IMPLND 4 0.064 COPY 501 15 IMPLND 5 0.01 COPY 501 15 East Basin*** PERLND 18 0.1814 COPY 502 12 PERLND 18 0.1814 COPY 502 13 IMPLND 1 0.013 COPY 502 15 IMPLND 4 0.0661 COPY 502 15 IMPLND 5 0.0113 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 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 Varma 3-Lot 1/21/2026 3:50:27 PM Page 36 RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1.167 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1.167 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 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> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 Varma 3-Lot 1/21/2026 3:50:27 PM Page 37 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 Varma 3-Lot 1/21/2026 3:50:27 PM Page 38 Predeveloped HSPF Message File Varma 3-Lot 1/21/2026 3:50:27 PM Page 39 Mitigated HSPF Message File Varma 3-Lot 1/21/2026 3:50:27 PM Page 40 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. 2005-2026; 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 Varma Renton 3 Lot Short Plat Technical Information Report Appendix D Operations and Maintenance Manual