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HomeMy WebLinkAboutSM01 Drainage Control Plan Proposed Indoor Athletic Facility Preliminary Stormwater Control Plan Date Prepared 4/9/2026 Subject Property 718 Yelm Ave W & 209 NW Cullens Rd Yelm, WA 98597 TPN: 21724140900 & 21724141001 Applicant Yelm Sports Group LLC Reviewing Agency City of Yelm Project Engineer Nicholas D. Taylor, PE The Iris Group PLLC (360) 890-8955 ntaylor@irisgroupconsulting.com "I hereby certify that this Stormwater Control Plan has been prepared by me or under my supervision and meets minimum standards of the 2024 Washington State Department of Ecology Stormwater Management Manual for Western Washington and normal standards of engineering practice. I hereby acknowledge and agree that the jurisdiction does not and will not assume liability for the sufficiency, suitability, or performance of drainage facilities designed by me." 4/9/2026 2 of 10 Table of Contents Section 1 – Proposed Project Description ..................................................................................................................... 3 Minimum Requirements ............................................................................................................................................ 3 MR #1 – Preparation of Drainage Control Plans .................................................................................................... 3 MR #2 – Construction Stormwater Pollution Prevention ...................................................................................... 3 MR #3 – Source Control of Pollution ..................................................................................................................... 3 MR #4 – Preservation of Natural Drainage Systems and Outfalls ......................................................................... 7 MR #5 – Onsite Stormwater Management ............................................................................................................ 7 MR #6 – Runoff Treatment .................................................................................................................................... 7 MR #7 – Flow Control ............................................................................................................................................ 7 MR #8 – Wetlands Protection ................................................................................................................................ 8 MR #9 – Operation and Maintenance ................................................................................................................... 8 Section 2 – Existing Conditions ...................................................................................................................................... 8 Section 3 – Soils Investigation ....................................................................................................................................... 8 Section 4 – Wells and Septic Systems ............................................................................................................................ 8 Section 5 – Fuel Tanks ................................................................................................................................................... 8 Section 6 – Subbasin Description .................................................................................................................................. 9 Section 7 – Floodplain Analysis ...................................................................................................................................... 9 Section 8 – Aesthetic Considerations for Facilities ........................................................................................................ 9 Section 9 – Facility Selection and Sizing ........................................................................................................................ 9 Section 10 – Conveyance System .................................................................................................................................. 9 Section 11 – Offsite Analysis & Mitigation .................................................................................................................... 9 Section 12 – Covenants, Dedications, Easements, Agreements .................................................................................. 10 Section 13 – Other Permits or Conditions Placed on the Project ................................................................................ 10 Attachments A. SWMM Figures B. Stormwater Site Plan C. NRCS Soils Report D. Existing Conditions Map E. WWHM Stormwater Model Output F. Geotechnical Report G. Operations and Maintenance Manual (Placeholder) H. PerkFilter Data 3 of 10 Section 1 – Proposed Project Description This Stormwater Control Plan (SCP) is in accordance with the 2024 Washington State Department of Ecology Stormwater Management Manual for Western Washington (SWMMWW). The SWMMWW was used to determine the applicable requirements for this project, including both the type of drainage plan and minimum requirements. This proposed project falls under New Development, as the impervious site coverage is currently less than 35%. Project Description: The project includes construction of an indoor athletic complex, parking lot, and associated appurtenances on a 2.78-acre parcel in the City of Yelm. Proposed Improvements: Proposed on-site improvements include an office/multipurpose building, four (4) standalone sport court buildings, walkway and sidewalk areas, and an impervious parking lot. A new driveway is proposed off NW Cullens Rd, as is a new public sidewalk within the Cullens Rd right of way. See proposed surface coverage in Table 1. Table 1 – Surface Coverage Minimum Requirements Per SWMMWW Volume 1, figures I-3.1 and I-3.3, of which annotated versions are provided as Attachment A to this report, Minimum Requirements #1-#9 apply to the new and replaced hard surfaces, as well as converted vegetation areas. MR #1 – Preparation of Drainage Control Plans Preparation of this SCP meets the intent of Minimum Requirement #1. MR #2 – Construction Stormwater Pollution Prevention A Construction Stormwater Pollution Prevention Plan will be prepared as part of the civil permit application for this project. MR #3 – Source Control of Pollution The following BMPs shall be utilized. S411 BMPs for Landscaping and Lawn / Vegetation Management Landscaping can include grading, soil transfer, vegetation planting, and vegetation removal. Examples include weed control on golf course lawns, access roads, and utility corridors and during landscaping; and residential lawn/plant care. Proper management of vegetation can minimize excess nutrients and pesticides. Maintain appropriate vegetation to control erosion and the discharge of stormwater pollutants. Prevent debris contamination of stormwater. Where practicable, grow plant species appropriate for the site, or adjust the soil properties of the site to grow desired plant species. Area (SF) New Pollution Generating Hard Surface 57,218 Proposed Effective Hard Surface 0 Disturbed Area 120,916 4 of 10 • Landscaping and Lawn/Vegetation Management: Install engineered soil/landscape systems to improve the infiltration and regulation of stormwater in landscaped areas. • Select the right plants for the planting location based on proposed use, available maintenance, soil conditions, sun exposure, water availability, height, sight factors, and space available. • Ensure that plants selected for planting are not on the noxious weed list. For example, butterfly bush often gets planted as an ornamental but is actually on the noxious weed list. • The Washington State Noxious Weed List can be found at the following webpage: https://www.nwcb.wa.gov/printable-noxious-weed-list • Do not dispose of collected vegetation into waterways or storm sewer systems. • Do not blow vegetation or other debris into the drainage system. • Dispose of collected vegetation such as grass clippings, leaves, sticks by composting or recycling. • Remove, bag, and dispose of class A & B noxious weeds in the garbage immediately. • Do not compost noxious weeds as it may lead to spreading through seed or fragment if the composting process is not hot enough. • Use manual and/or mechanical methods of vegetation removal (pincer-type weeding tools, flame weeders, or hot water weeders as appropriate) rather than applying herbicides, where practical. • Use at least an eight-inch "topsoil" layer with at least 8 percent organic matter to provide a sufficient vegetation-growing medium. o Organic matter is the least water-soluble form of nutrients that can be added to the soil. Composted organic matter generally releases only between 2 and 10 percent of its total nitrogen annually, and this release corresponds closely to the plant growth cycle. Return natural plant debris and mulch to the soil, to continue recycling nutrients indefinitely. • Select the appropriate turfgrass mixture for the climate and soil type. o Certain tall fescues and rye grasses resist insect attack because the symbiotic endo-phytic fungi found naturally in their tissues repel or kill common leaf and stem-eating lawn insects.  The fungus causes no known adverse effects to the host plant or to humans.  Tall fescues and rye grasses do not repel root-feeding lawn pests such as Crane Fly larvae.  Tall fescues and rye grasses are toxic to ruminants such as cattle and sheep o Endophytic grasses are commercially available; use them in areas such as parks or golf courses where grazing does not occur. o Local agricultural or gardening resources such as Washington State University Extension office can offer advice on which types of grass are best suited to the area and soil type. • Adjusting the soil properties of the subject site can assist in selection of desired plant species. Consult a soil restoration specialist for site-specific conditions. • Conduct mulch-mowing whenever practicable. • Use native plants in landscaping. Native plants do not require extensive fertilizer or pesticide applications. Native plants may also require less watering. • Use mulch or other erosion control measures on soils exposed for more than one week during the dry season (May 1 to September 30) or two days during the rainy season (October 1 to April 30). • Till a topsoil mix or composted organic material into the soil to create a well-mixed transition layer that encourages deeper root systems and drought-resistant plants. • Apply an annual topdressing application of 3/8” compost. Amending existing landscapes and turf systems by increasing the percent organic matter and depth of topsoil can: o Substantially improve the permeability of the soil. o Increase the disease and drought resistance of the vegetation. o Reduces the demand for fertilizers and pesticides. 5 of 10 • Disinfect gardening tools after pruning diseased plants to prevent the spread of disease. • Prune trees and shrubs in a manner appropriate for each species. • If specific plants have a high mortality rate, assess the cause and replace it with another more appropriate species. S417 BMPs for Maintenance of Stormwater Drainage and Treatment Systems Facilities include roadside catch basins on arterials and within residential areas, conveyance systems, detention facilities such as ponds and vaults, oil/water separators, biofilters, settling basins, infiltration systems, and all other types of stormwater treatment systems presented in SWMM Volume V. Oil and grease, hydrocarbons, debris, heavy metals, sediments and contaminated water are found in catch basins, oil and water separators, settling basins, etc. Oil and grease, hydrocarbons, debris, heavy metals, sediments and contaminated water are found in catch basins, oil and water separators, settling basins, etc. Provide maintenance and cleaning of debris, sediments, and other pollutants from stormwater collection, conveyance, and treatment systems to maintain proper operation. Maintain stormwater treatment facilities per the operations and maintenance (O&M) procedures presented in SWMM Appendix V-A: BMP Maintenance Tables in addition to the following BMPs: • Inspect and clean treatment BMPs, conveyance systems, and catch basins as needed, and determine necessary O&M improvements. • Promptly repair any deterioration threatening the structural integrity of stormwater facilities. These include replacement of clean-out gates, catch basin lids, and rock in emergency spillways. • Ensure adequacy of storm sewer capacities and prevent heavy sediment discharges to the sewer system. • Regularly remove debris and sludge from BMPs used for peak-rate control, treatment, etc. and discharge to a sanitary sewer if approved by the sewer authority, or truck to an appropriate local or state government approved disposal site. • Clean catch basins when the depth of deposits reaches 60 percent of the sump depth as measured from the bottom of basin to the invert of the lowest pipe into or out of the basin. However, in no case should there be less than six inches clearance from the debris surface to the invert of the lowest pipe. Some catch basins (for example, WSDOT's Catch Basin Type 1L (WSDOT, 2011) may have as little as 12 inches sediment storage below the invert. These catch basins need frequent inspection and cleaning to prevent scouring. Where these catch basins are part of a stormwater collection and treatment system, the system owner/operator may choose to concentrate maintenance efforts on downstream control devices as part of a systems approach. • Properly dispose of all solids, polluted material, and stagnant water collected through system cleaning. Do not decant water back into the drainage system from eductor trucks or vacuum equipment since there may be residual contaminants in the cleaning equipment. Do not jet material downstream into the public drainage system. • Clean woody debris in a catch basin as frequently as needed to ensure proper operation of the catch basin. • Post warning signs; “Dump No Waste - Drains to Ground Water,” “Streams,” “Lakes,” or emboss on or adjacent to all storm drain inlets where possible. • Disposal of sediments and liquids from the catch basins must comply with SWMM Appendix IV-B: Management of Street Waste Solids and Liquids. S451 BMPs for Building Repair, Remodeling, Painting, and Construction 6 of 10 This activity refers to the construction of buildings and other structures, remodeling of existing buildings and houses, general exterior building repair work, and containment or removal of known or suspected exterior hazardous building materials. Pollutants of concern include toxic hydrocarbons, hazardous wastes, toxic organics (such as PCBs), suspended solids, heavy metals, pH, oils, and greases. PCBs were added to building materials before 1980 (such as caulk and other sealants, joint materials, paint, siding, roofing, and others), and now with age and weathering are at greater risk of being dislodged during demolition and renovation activities. Particles containing PCBs can be washed into the stormwater, contaminating the conveyance system and downstream water bodies, if not properly managed. Prior to 1980, PCB-containing building materials were more often used in public buildings such as schools, hospitals, universities, fire houses, police stations, government offices, military sites, as well as privately owned commercial and large multi-unit residential buildings. Recently, guidance has been developed for characterizing and abating PCBs in building materials that will undergo demolition or renovation (Ecology, 2024). The user should refer to this document for more details on preventing PCBs from entering stormwater. Educate employees about the need to control site activities. Control leaks, spills, and loose material. Utilize good housekeeping practices. Regularly clean up debris that can contaminate stormwater. Protect the drainage system from dirty runoff and loose particles. Prevent PCB-containing dust and solids from entering stormwater and stormwater conveyances. • Identify, remove, and properly dispose of hazardous substances from the building before beginning repairing or remodeling activities that could expose them to stormwater. Such substances could include PCBs, asbestos, lead paint, mercury switches, and electronic waste. • Follow Ecology’s guidance document How to Find and Address PCBs in Building Materials (Ecology, 2024) for PCB-containing building materials undergoing demolition or renovation. • When removing suspected PCB-containing materials, avoid working in high wind conditions or take extra precautions when working in wind strong enough to move dust and debris. This could include constructing a wind screen of plastic at the edge of the groundcover to keep dust and debris from spreading. • Contact the local jurisdiction’s stormwater program to inform them when PCB-containing materials are, or are likely to be, present. They may be able to prioritize street sweeping and/or storm drainpipe cleaning in the area. • Educate employees about the need to control site activities to prevent stormwater pollution and train them in spill cleanup procedures. Employees may also include maintenance and landscaping staff working around buildings with exterior PCB-containing materials. • At all times, have available at the work site spill cleanup materials appropriate to the chemicals used on site. • Clean up the work site at the end of each workday. Put away materials (such as solvents) indoors or cover and secure them, so that unauthorized individuals will not have access to them. • Sweep the area daily to collect loose litter, paint chips, grit, and dirt. • Use a HEPA vacuum below painted walls, caulking seams, windows, doors, downspouts, and any specific exterior features known or suspected of containing PCBs. • Do not dump any liquid on pavement, on the ground, in the storm drain, or toward the storm drain, regardless of its content, unless it is clean water only. • Place a drop cloth, where space and access permits, before beginning wood treating activities. Use drip pans in areas where drips are likely to occur if the area cannot be protected with a drop cloth. 7 of 10 • Use ground or drop cloths underneath scraping and sandblasting work. Use ground cloths, buckets, or tubs anywhere that work materials are laid down. • Clean paint brushes and other tools covered with water-based paints in sinks connected to sanitary sewers or in portable containers that can subsequently be dumped into a sanitary sewer drain. • Clean brushes and tools covered with non-water-based finishes or other materials in a manner that enables collection of used solvents for recycling or proper disposal. Do not dis-charge non-water-based finishes or paints or used solvents into the sanitary sewer, or any other drain. • Use storm drain covers, or similarly effective devices, to prevent dust, grit, wash water, or other pollutants from escaping the work area. Place the cover or containment device over the storm drain at the beginning of the workday. Collect and properly dispose of accumulated dirty runoff and solids before removing the cover or device at the end of each workday. • If storm drain covers are not feasible, install and maintain filter inserts in all catch basins that may receive stormwater from the work site (i.e. on the work site property and adjacent street(s)). • Lightly spray water on the work site to control dust and grit that could blow away. Do not use oils for dust control. Never spray to the point of water runoff from the site. • Clean tools over a ground cloth or within a containment device such as a tub. • Consider using filtered vacuuming to collect waste that may be hard to sweep, such as dust on a drop cloth. • If conducting work in wet weather conditions, consider setting up temporary cover when scraping or pressure-washing lead-based paint. • Use tools and work methods that generate the least dust and heat. Consider using manual tools, as they generate less fine dust and heat. MR #4 – Preservation of Natural Drainage Systems and Outfalls In the existing condition there is no significant outfall at which concentrated flow enters or leaves the site. Site topography within the construction limits slopes gently to the South. There is little to no offsite run-on to the development area. Runoff from the proposed impervious surfaces will all be collected and infiltrated onsite, thereby preserving the sites natural drainage system. MR #5 – Onsite Stormwater Management SWMMWW Figure I-3.3, as annotated and provided in Attachment A, was used to identify and select BMPs for management of stormwater. Following Figure I-3.3, the project chooses to meet the LID Performance Standard. See Attachment E for WWHM output indicating that the LID Performance Standard is met. Refer to Section 9 for facility selection and sizing. MR #6 – Runoff Treatment As the project proposes more than 5,000 SF of pollution generating hard surface, runoff treatment facilities are required. The project will utilize a stormwater filter unit to address this requirement. Refer to Section 9 for facility selection and sizing. MR #7 – Flow Control The following circumstances require achievement of the standard flow control requirement for western Washington: 1. Projects in which the total of effective impervious surfaces is 10,000 square feet or more in a threshold discharge area, or There is less than 10,000 SF of proposed effective impervious surface for this project. 8 of 10 2. Projects that convert ¾ acres or more of vegetation to lawn or landscape, or convert 2.5 acres or more of native vegetation to pasture in a threshold discharge area, and from which there is a surface discharge in a natural or manmade conveyance system from the site, or The project proposes to convert less than ¾ acres of vegetation to lawn or landscape and to convert less than 2.5 acres of native vegetation to pasture. 3. Projects that, through a combination of effective hard surfaces and converted pervious surfaces, cause a 0.15 cubic feet per second increase in the 100-year flow frequency from a threshold discharge area, as estimated using WWHM, MGSFlood, or other approved model using 15-minute time steps. The 0.15 cfs increase is a comparison of the post-project runoff to the existing condition runoff. For purposes of applying this threshold, the existing condition is the preproject (i.e. existing) land cover. Using WWHM to model runoff from the project’s limits of disturbance, the pre-developed discharge is 0.0123 cfs, and the post-project discharge is 0.0 cfs. Thus, the project results in a 0.0123 cfs reduction in the 100-year flow frequency. See Attachment E for WWHM output. MR #8 – Wetlands Protection As this project does not discharge into a wetland, Minimum Requirement #8 is not applicable to this project. MR #9 – Operation and Maintenance An operations and maintenance manual will be prepared as part of the final SCP. Section 2 – Existing Conditions The site is an undeveloped parcel, as depicted on the Existing Conditions Map included as Attachment D. Existing grades are based on a topographic and boundary survey prepared by Butler Surveying Inc., dated 7/25/2025. Section 3 – Soils Investigation The NRCS Soils Report, Attachment C, indicates that site soils are Spanaway gravelly sandy loam with 0 to 3 percent slopes, and Spanaway stony sandy loam with 0 to 3 percent slopes. Both soils are type A, which indicates ideal infiltration characteristics. A Geotechnical Report, Attachment F, was completed by Mud Bay Geotechnical Services, LLC, on 11/4/2025. The report found site soil as moist, dark brown, topsoil from surface down to 1.5’ bgs, underlain by moist, brown, poorly graded gravel with or without sand down to 14’ bgs. Groundwater was not encountered during the subsurface exploration, although the report indicates a seasonally high groundwater table elevation as shallow as 12’ bgs within the surrounding area. The site is not mapped as a critical aquifer. The report also identified a design infiltration rate of 17.7 in/hr was found approximately 8’ bgs. Section 4 – Wells and Septic Systems There are no existing wells or septic systems within the project limits of disturbance. The project proposes to connect to the available city water and sewer utilities within the right of way. Section 5 – Fuel Tanks There is no indication of existing above or below grade fuel tanks on the property. There are no proposed fuel tanks as a part of this project. 9 of 10 Section 6 – Subbasin Description There is no off-site drainage tributary to the project. Section 7 – Floodplain Analysis Per Thurston County GIS data the subject parcel is not within a flood plain. The FEMA flood map service identifies the site within Zone X, which is an area of minimal flood hazard. Section 8 – Aesthetic Considerations for Facilities The proposed BMP is an infiltration gallery, thus aesthetic considerations are unnecessary. Section 9 – Facility Selection and Sizing Lawn and Landscaped Areas The Post-Construction Soil Quality and Depth BMP, T5.13, is the first and only BMP for this type of surface, and it will be applied to all disturbed surfaces that are to remain impervious. See Attachment G for Stormwater BMP details. Roofs Roof surface runoff will be mitigated on site with BMP T7.20: Infiltration Trenches. The project proposes a single infiltration gallery to infiltrate runoff from all impervious surfaces. The infiltration gallery will consist of one (1) 120’ length of 96” diameter perforated pipe, which is designed and manufactured by Contech specifically for this purpose. The Contech perforated pipe will be buried in a chamber beneath the parking lot as depicted in the Stormwater Site Plan. WWHM was used to size the gallery to ensure 100% infiltration of proposed runoff. See Attachment E for the WWHM report. Other Hard Surfaces Runoff from driveway surfaces will be managed with BMP T7.20: Infiltration Trenches, and treatment will be provided with the use of a manufactured treatment device. Prior to comingling with roof runoff for infiltration into the gallery, driveway runoff will pass through an Oldcastle PerkFilter Manhole, which is Ecology GULD approved and will provide basic & phosphorus treatment. The WWHM report indicates an offline treatment flow rate of 0.1149 cfs, and the proposed PFMH-72-24 PerkFilter unit is rated for up to a 0.151 cfs treatment flow rate. As mentioned in the paragraph above, the infiltration gallery with the 120’ long, 96” diameter perforated pipe was sized to ensure 100% infiltration of runoff from all proposed impervious surfaces. See Attachment E for the WWHM report and the Stormwater Site Plan for the PerkFilter detail. Tabulation of basin areas is included in Table 1, above. Section 10 – Conveyance System The roof downspout and walkway system will consist of 6” PVC piping elements, type 1 catch basins, and a type 2 catch basin. The slope of the 6” PVC piping will be greater than or equal to 1% in accordance with the Uniform Plumbing Code. The parking lot runoff collection system will consist of 12” PVC piping elements, type 1 catch basins, and a manufactured treatment device specified in the Stormwater Site Plan. The slope of the 12” PVC piping will be greater than or equal to 0.5% in accordance with the Uniform Plumbing Code. Section 11 – Offsite Analysis & Mitigation This section is not applicable as stormwater will not be discharged to an offsite conveyance. 10 of 10 Section 12 – Covenants, Dedications, Easements, Agreements There will be a proposed access easement for site entrance from Yelm Ave SE. Section 13 – Other Permits or Conditions Placed on the Project A building permit and NPDES construction stormwater discharge permit will be required for the project. There are currently no known conditions of approval. Attachment A Attachment B RD RD SD SD SD RD RD RD RD RD RD RD RD RD SD SD SD SD SD SD SD SD SD SD SD SD SD SD SD SD SD SDSDSDSDSDSD RD RDRDRD SS SS SS SS SS SS SS SS SS SS SS W W W W W W W W W W W W W W W W W W W W W W W W W W W W RD SD SD SD SD C C C C C C C C C C C C C C C C CCCC FI L E N A M E : Z: \ P \ S M 0 1 \ C A D \ S h e e t s \ S M 0 1 P r e l i m i n a r y S i t e P l a n . d w g D A T E / T I M E : 4/ 9 / 2 0 2 6 3 : 5 6 : 3 6 P M SI T E P L A N PR O P O S E D I N D O O R AT H L E T I C F A C I L I T Y NDT WRK 04-09-2026 SM01 NDT C1 1 1 SCALE IN FEETSCALE IN FEET 30150 45 60 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 A B C D E F G H I J 3 6 0 - 8 9 0 - 8 9 5 5 | 2 9 9 N M a r k e t B l v d , C h e h a l i s , W A 9 8 5 3 2 DESIGNED BY: DRAWN BY: DATE: PROJ. NO: OF REVIEWED BY: Know what's BELOW Call 811 before you dig. NICHOLAS DAVID AYLORSTATEOFWASHINGTON REGISTERED PROFESSIONAL ENGINEER T 4611304/ 0 9 / 2 0 2 6 100' 70 ' 50' 75 ' 5' 5' 10' YE L M A V E S E NW CULLENS RD VICINITY MAP NOT TO SCALE KEY NOTES 1.PROPOSED 7,000 SF INDOOR ATHLETIC FACILITY (TYP) 2.PROPOSED 3,750 SF OFFICE / ADMINISTRATION BUILDING 3.PROPOSED CONCRETE WALKWAY 4.PROPOSED PAVED PARKING AREA 5.PROPOSED LANDSCAPING PER SEPARATE LANDSCAPING PLAN (TYP) 6.PROPOSED REFUSE AND RECYCLING AREA 7.PROPOSED 31' DRIVEWAY 8.PROPOSED 5' PUBLIC SIDEWALK 9.PROPOSED 53' ACCESS EASEMENT 10.PROPOSED SANITARY SEWER LATERAL 11.PROPOSED PRIVATE SANITARY SEWER MANHOLE (TYP) 12.PROPOSED CONNECTION TO EXISTING SANITARY SEWER 13.PROPOSED WATER MAIN LOOP EXTENSION 14.PROPOSED WATER SERVICE LATERAL 15.PROPOSED 6" ROOF DRAIN PIPING 16.PROPOSED 6" STORM DRAIN PIPING 17.PROPOSED STORMWATER CLEANOUT 18.PROPOSED TYPE 1 CB WITH LOCKING VANED GRATE (TYP) 19.PROPOSED STORMWATER TREATMENT TYPE 2 CB WITH MANHOLE 20.PROPOSED TYPE 2 CB WITH SOLID LOCKING LID 21.PROPOSED STORMWATER INFILTRATION GALLERY 22.PROPOSED 90° STANDARD PARKING STALL (TYP) 23.PROPOSED 60° STANDARD PARKING STALL (TYP) 24.PROPOSED 60° COMPACT PARKING STALL (TYP) 25.PROPOSED 60° ACCESSIBLE STALL (TYP) 26.PROPOSED 60° VAN ACCESSIBLE STALL 27.PROPOSED CROSSWALK (TYP) 28.PROPOSED 10' TALL 36 SF ELECTRONIC FREE STANDING SIGN 29.PROPOSED 6' TALL 51 SF MONUMENT SIGN 30.EXISTING ROW LINE 31.EXISTING ROW LINE AFTER 5' DEDICATION 32.EXISTING SIDEWALK 33.EXISTING DENTAL OFFICE 34.EXISTING DENTAL OFFICE PARKING LOT 35.PROPOSED BOUNDARY LINE AFTER ADJUSTMENT # ·EXISTING HARD SURFACE: 0 SF ·NEW HARD SURFACE (ROOF):31,750 SF ·NEW HARD SURFACE (OTHER):70,220 SF ·TOTAL NEW PLUS REPLACED HARD SURFACE:101,970 SF ·TOTAL HARD SURFACE AFTER PROJECT:101,970 SF ·NEW POLLUTION GENERATING HARD SURFACE:57,218 SF ·PROPOSED EFFECTIVE HARD SURFACE:0 SF ·DISTURBED AREA 120,916 SF SITE COVERAGE DATA (WITHIN LOD) SITE DATA PARCEL #:21724140900, 21724141001 SITE ADDRESS: 718 YELM AVE W & 209 CULLENS ST SE YELM, WA 98597 GROSS ACREAGE: 2.78 AC ZONING:C-1 EXISTING USE: COMMERCIAL, VACANT PRESIDING JURISDICTION:YELM, WA EXISTING FEATURES ARE APPROXIMATELY AS DEPICTED IN A TOPOGRAPHIC AND BOUNDARY SURVEY PREPARED BY BUTLER SURVEYING INC., DATED 7/25/25. ALL EXISTING FEATURES AND TOPOGRAPHY SHOWN SHALL BE VERIFIED AT CONTRACTOR'S EXPENSE PRIOR TO BEGINNING CONSTRUCTION. ANY AND ALL DISCREPANCIES FOUND BETWEEN ACTUAL EXISTING CONDITIONS AND THE EXISTING CONDITIONS SHOWN HERE SHALL BE IDENTIFIED TO THE PROJECT ENGINEER PRIOR TO CONTINUANCE OF ANY WORK. BASIS OF BEARINGS: WASHINGTON STATE PLANE SOUTH ZONE (NAD 83/2011) DERIVED FROM TIES TO THURSTON COUNTY CONTROL POINTS #1252TBM AND #253. HELD THE PUBLISHED COORDINATE AT "1252TBM" AND APPLIED THE COMBINED SCALE FACTOR OF 0.999921334 TO PRODUCE THE GROUND DISTANCES DEPICTED HEREON. BASIS OF ELEVATIONS: NORTH AMERICAN VERTICAL DATUM OF 1988 (NAVD 88) RELATIVE TO THURSTON COUNTY CONTROL POINT #1252TBM HAVING A PUBLISHED ELEVATION OF 349.818' (NAVD 88). EXISTING CONDITIONS SITE 31' 18.6' 53 ' 1 2 3 4 5 6 7 5' 8 9 10 11 12 13 14 15 16 17 18 19 20 21 32 33 34 EXISTING COMMERCIAL BUILDING PROPOSED INDOOR ATHLETIC FACILITY PROPOSED INDOOR ATHLETIC FACILITY PROPOSED INDOOR ATHLETIC FACILITY PROPOSED INDOOR ATHLETIC FACILITY PR O P O S E D OF F I C E / MU L T I P U R P O S E BU I L D I N G 23 24 22 ' 8.5' 18 '18 ' 23'23' 7.6'5' 5' 8. 5 ' 20' 5' 5' 6. 7 ' 5' 5' 20' 10 ' 5' 10' 20.4' 23 ' 30 '25 ' 17 ' 18' 9.2 ' 23.1' 8.7' 2625 22 27 28 29 31 30 REQUIRED STALLS:172 PROPOSED STANDARD STALLS:152 PROPOSED COMPACT STALLS:20 *TOTAL PROPOSED STALLS:172 *INCLUDES 6 ACCESSIBLE STALLS, ONE OF WHICH IS VAN ACCESSIBLE PARKING 35 35 Attachment C United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Thurston County Area, WashingtonNatural Resources Conservation Service March 9, 2026 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................11 Map Unit Descriptions.........................................................................................11 Thurston County Area, Washington................................................................13 110—Spanaway gravelly sandy loam, 0 to 3 percent slopes......................13 112—Spanaway stony sandy loam, 0 to 3 percent slopes..........................13 References............................................................................................................15 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and Custom Soil Resource Report 6 identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. Custom Soil Resource Report 7 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 9 Custom Soil Resource Report Soil Map 51 9 9 3 1 0 51 9 9 3 4 0 51 9 9 3 7 0 51 9 9 4 0 0 51 9 9 4 3 0 51 9 9 4 6 0 51 9 9 4 9 0 51 9 9 5 2 0 51 9 9 3 1 0 51 9 9 3 4 0 51 9 9 3 7 0 51 9 9 4 0 0 51 9 9 4 3 0 51 9 9 4 6 0 51 9 9 4 9 0 51 9 9 5 2 0 529180 529210 529240 529270 529300 529330 529360 529390 529420 529450 529480 529510 529180 529210 529240 529270 529300 529330 529360 529390 529420 529450 529480 529510 46° 56' 55'' N 12 2 ° 3 7 ' 0 ' ' W 46° 56' 55'' N 12 2 ° 3 6 ' 4 3 ' ' W 46° 56' 47'' N 12 2 ° 3 7 ' 0 ' ' W 46° 56' 47'' N 12 2 ° 3 6 ' 4 3 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 50 100 200 300 Feet 0 20 40 80 120 Meters Map Scale: 1:1,650 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Thurston County Area, Washington Survey Area Data: Version 19, Aug 28, 2025 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: May 26, 2023—Aug 14, 2023 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 10 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 110 Spanaway gravelly sandy loam, 0 to 3 percent slopes 3.2 72.2% 112 Spanaway stony sandy loam, 0 to 3 percent slopes 1.2 27.8% Totals for Area of Interest 4.4 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, Custom Soil Resource Report 11 onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 12 Thurston County Area, Washington 110—Spanaway gravelly sandy loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 2ndb6 Elevation: 330 to 1,310 feet Mean annual precipitation: 35 to 65 inches Mean annual air temperature: 50 degrees F Frost-free period: 150 to 200 days Farmland classification: Prime farmland if irrigated Map Unit Composition Spanaway and similar soils: 100 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Spanaway Setting Landform: Terraces, Outwash plains Parent material: Volcanic ash over gravelly outwash Typical profile H1 - 0 to 15 inches: gravelly sandy loam H2 - 15 to 20 inches: very gravelly loam H3 - 20 to 60 inches: extremely gravelly sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Drainage class: Somewhat excessively drained Capacity of the most limiting layer to transmit water (Ksat): High (1.98 to 5.95 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water supply, 0 to 60 inches: Low (about 3.8 inches) Interpretive groups Land capability classification (irrigated): 3s Land capability classification (nonirrigated): 3s Hydrologic Soil Group: A Ecological site: R002XA006WA - Puget Lowlands Dry Prairie Forage suitability group: Droughty Soils (G002XS401WA) Other vegetative classification: Droughty Soils (G002XS401WA) Hydric soil rating: No 112—Spanaway stony sandy loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 2ndb8 Custom Soil Resource Report 13 Elevation: 660 to 1,310 feet Mean annual precipitation: 35 to 65 inches Mean annual air temperature: 50 degrees F Frost-free period: 150 to 200 days Farmland classification: Farmland of statewide importance Map Unit Composition Spanaway and similar soils: 100 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Spanaway Setting Landform: Terraces, Outwash plains Parent material: Volcanic ash over gravelly outwash Typical profile H1 - 0 to 16 inches: stony sandy loam H2 - 16 to 22 inches: very gravelly sandy loam H3 - 22 to 60 inches: extremely gravelly sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Drainage class: Somewhat excessively drained Capacity of the most limiting layer to transmit water (Ksat): High (1.98 to 5.95 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water supply, 0 to 60 inches: Low (about 4.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4s Hydrologic Soil Group: A Ecological site: R002XA006WA - Puget Lowlands Dry Prairie Forage suitability group: Droughty Soils (G002XS401WA) Other vegetative classification: Droughty Soils (G002XS401WA) Hydric soil rating: No Custom Soil Resource Report 14 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 15 United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report 16 Attachment D Map Title 0 50 100 ft Legend Planning and Land Use Other Historic Sites Thurston County Historic Register Sites Jurisdictions Annexations - Bucoda 313 460 464 NA Annexations - Lacey 1 1011 1061 1062 1096 1202 1209 1286 1288 1304 1347 1470 1509 1512 1518 1521 1529 1570 1580 1589 1590 1596 1618 175 205 233 406 55 555 56 564 570 572 585 596 598 704 715 750 759 782 819 851 853 884 903 906 918 929 940 963 972 977 996 <all other values> Annexations - Olympia 3307 5160 5161 5209 5210 5277 5286 5308 5446 5469 5472 5634 5686 5761 5810 5870 6352 6396 6418 6423 6431 6432 6433 6467 6477 6488 6859 6870 6876 6897 7029 NA Annexations - Rainier 304 359 387 388 390 397 398 407 510 527 544 551 561 638 NA <all other values> Annexations - Tenino 613 616 625 663 665 721 724 741 742 747 ASR READJ NA Annexations - Tumwater 02000-022 02001-024 02004-007 02004-010 02004-018 02004-031 02004-039 02005-008 02005-039 02006-024 02013-007 02015-008 02022-001 02022-002 094-006 095-040 095-041 097-006 1006 1013 1014 1035 1041 1047 1048 1060 1065 1094 1136 1139 1145 1158 1193 1194 1197 1207 1269 1274 1284 1338 1339 1347 1396 14027 1944 ELCTN 2000-005 2003-012 2004-020 2005-010 2005-016 2005-017 2005-028 2005-036 2005-038 2006-002 2006-010 2006-028 2006-22 2008-001 2008-002 2008-003 2015-004 265 266 267 268 269 270 271 272 273 275 276 277 278 279 280 281 282 311 339 506 516 533 534 536 546 551 566 599 628 629 640 691 710 711 715 740 748 762 768 770 782 813 824 825 826 855 908 925 927 936 946 969 972 980 990 NA O2017-031 O2017-032 O2018-017 O2018-024 O94-005 <all other values> Annexations - Yelm 07-0233 1054 1097 153 160 320 390 408 433 441 443 461 462 465 474 484 513 528 529 534 543 554 577 585 605 616 627 648 827 831 872 NA <all other values> Parcels Parcel Boundaries Author: Published:9/4/2026 Notes The information included on this map has been compiled by Thurston County staff from a variety of sources and is subject to change without notice. Additional elements may be present in reality that are not represented on the map. Ortho-photos and other data may not align. The boundaries depicted by these datasets are approximate. This document is not intended for use as a survey product. ALL DATA IS EXPRESSLY PROVIDED ‘AS IS’ AND ‘WITH ALL FAULTS’. Thurston County makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness, or rights to the use of such information. In no event shall Thurston County be liable for direct, indirect, incidental, consequential, special, or tort damages of any kind, including, but not limited to, lost revenues or lost profits, real or anticipated, resulting from the use, misuse or reliance of the information contained on this map. If any portion of this map or disclaimer is missing or altered, Thurston County removes itself from all responsibility from the map and the data contained within. The burden for determining fitness for use lies entirely with the user and the user is solely responsible for understanding the accuracy limitation of the information contained in this map. Authorized for 3rd Party reproduction for personal use only. © 2026 Thurston County Attachment E WWHM2012 PROJECT REPORT sm01 3/17/2026 3:03:33 PM Page 2 General Model Information WWHM2012 Project Name:sm01 Site Name:Athletic Complex Site Address: City:Yelm, WA Report Date:3/17/2026 Gage:Eaton Creek Data Start:1955/10/01 Data End:2011/09/30 Timestep:15 Minute Precip Scale:0.857 Version Date:2025/05/13 Version:4.3.2 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year Low Flow Threshold for POC2:50 Percent of the 2 Year High Flow Threshold for POC2:50 Year sm01 3/17/2026 3:03:33 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre A B, Forest, Flat 1.47 Pervious Total 1.47 Impervious Land Use acre Impervious Total 0 Basin Total 1.47 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 2 POC 2 sm01 3/17/2026 3:03:33 PM Page 4 Basin 2 Bypass:No GroundWater:No Pervious Land Use acre A B, Forest, Flat 1.31 Pervious Total 1.31 Impervious Land Use acre Impervious Total 0 Basin Total 1.31 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 1 POC 1 sm01 3/17/2026 3:03:33 PM Page 5 Mitigated Land Use Roof/Sidewalk/Ldscp Bypass:No GroundWater:No Pervious Land Use acre A B, Pasture, Flat 0.44 Pervious Total 0.44 Impervious Land Use acre ROOF TOPS FLAT 0.73 SIDEWALKS FLAT 0.3 Impervious Total 1.03 Basin Total 1.47 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Contech CMP 3 Contech CMP 3 sm01 3/17/2026 3:03:33 PM Page 6 PGHS Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre PARKING FLAT 1.31 Impervious Total 1.31 Basin Total 1.31 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Contech CMP 3 Contech CMP 3POC 1POC 1 sm01 3/17/2026 3:03:33 PM Page 7 Routing Elements Predeveloped Routing sm01 3/17/2026 3:03:34 PM Page 8 Mitigated Routing Contech CMP 3 CMP Diameter:96 Perferated?Yes Manifolds No Manifolds CMP Row Length (ft):120 CMP Total Length (ft)120 Top Stone Depth (ft):0.5 Bottom Stone Depth (ft):0.5 Chamber Spacing (ft):3 Discharge Structure Riser Height:6.91666666666667 ft. Riser Diameter:24 in. Element Flow Outlets: Outlet 1 Outlet 2 Outlets Flow To: Contechcmp Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.030 0.000 0.000 0.000 0.0500 0.030 0.000 0.000 0.540 0.1000 0.030 0.001 0.000 0.540 0.1500 0.030 0.001 0.000 0.540 0.2000 0.030 0.002 0.000 0.540 0.2500 0.030 0.003 0.000 0.540 0.3000 0.030 0.003 0.000 0.540 0.3500 0.030 0.004 0.000 0.540 0.4000 0.030 0.004 0.000 0.540 0.4500 0.030 0.005 0.000 0.540 0.5000 0.030 0.006 0.000 0.540 0.5889 0.030 0.007 0.000 0.540 0.7667 0.030 0.010 0.000 0.540 0.8556 0.030 0.011 0.000 0.540 0.9444 0.030 0.013 0.000 0.540 1.0333 0.030 0.014 0.000 0.540 1.2111 0.030 0.018 0.000 0.540 1.3000 0.030 0.020 0.000 0.540 1.3889 0.030 0.021 0.000 0.540 1.4778 0.030 0.023 0.000 0.540 1.6556 0.030 0.027 0.000 0.540 1.7444 0.030 0.029 0.000 0.540 1.8333 0.030 0.031 0.000 0.540 1.9222 0.030 0.033 0.000 0.540 2.1000 0.030 0.037 0.000 0.540 2.1889 0.030 0.039 0.000 0.540 2.2778 0.030 0.041 0.000 0.540 2.3667 0.030 0.043 0.000 0.540 2.5444 0.030 0.047 0.000 0.540 2.6333 0.030 0.049 0.000 0.540 2.7222 0.030 0.051 0.000 0.540 2.8111 0.030 0.054 0.000 0.540 2.9889 0.030 0.058 0.000 0.540 3.0778 0.030 0.060 0.000 0.540 3.1667 0.030 0.062 0.000 0.540 sm01 3/17/2026 3:03:34 PM Page 9 3.2556 0.030 0.064 0.000 0.540 3.4333 0.030 0.069 0.000 0.540 3.5222 0.030 0.071 0.000 0.540 3.6111 0.030 0.073 0.000 0.540 3.7000 0.030 0.075 0.000 0.540 3.8778 0.030 0.080 0.000 0.540 3.9667 0.030 0.082 0.000 0.540 4.0556 0.030 0.084 0.000 0.540 4.1444 0.030 0.087 0.000 0.540 4.3222 0.030 0.091 0.000 0.540 4.4111 0.030 0.093 0.000 0.540 4.5000 0.030 0.096 0.000 0.540 4.5889 0.030 0.098 0.000 0.540 4.7667 0.030 0.102 0.000 0.540 4.8556 0.030 0.105 0.000 0.540 4.9444 0.030 0.107 0.000 0.540 5.0333 0.030 0.109 0.000 0.540 5.2111 0.030 0.114 0.000 0.540 5.3000 0.030 0.116 0.000 0.540 5.3889 0.030 0.118 0.000 0.540 5.4778 0.030 0.120 0.000 0.540 5.6556 0.030 0.125 0.000 0.540 5.7444 0.030 0.127 0.000 0.540 5.8333 0.030 0.129 0.000 0.540 5.9222 0.030 0.131 0.000 0.540 6.1000 0.030 0.136 0.000 0.540 6.1889 0.030 0.138 0.000 0.540 6.2778 0.030 0.140 0.000 0.540 6.3667 0.030 0.142 0.000 0.540 6.5444 0.030 0.146 0.000 0.540 6.7222 0.030 0.150 0.000 0.540 6.8111 0.030 0.152 0.000 0.540 6.9889 0.030 0.156 0.411 0.540 7.0778 0.030 0.158 1.367 0.540 7.1667 0.030 0.160 2.623 0.540 7.2556 0.030 0.162 4.073 0.540 7.5222 0.030 0.168 8.626 0.540 7.6111 0.030 0.170 9.896 0.540 7.7000 0.030 0.172 10.92 0.540 7.8778 0.030 0.175 12.25 0.540 7.9667 0.030 0.177 12.91 0.540 8.0556 0.030 0.178 13.44 0.540 8.1444 0.030 0.180 13.96 0.540 8.3222 0.030 0.183 14.93 0.540 8.4111 0.030 0.184 15.40 0.540 8.5000 0.030 0.186 15.85 0.540 8.5500 0.030 0.186 16.10 0.540 8.6000 0.030 0.187 16.34 0.540 8.6500 0.030 0.187 16.58 0.540 8.7000 0.030 0.188 16.82 0.540 8.7500 0.030 0.189 17.05 0.540 8.8000 0.030 0.189 17.29 0.540 8.8500 0.030 0.190 17.51 0.540 8.9000 0.030 0.191 17.74 0.540 8.9500 0.030 0.191 17.96 0.540 9.0000 0.030 0.192 18.18 0.540 sm01 3/17/2026 3:03:34 PM Page 10 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:1.31 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:1.31 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.001015 5 year 0.001737 10 year 0.002398 25 year 0.003494 50 year 0.004537 100 year 0.005812 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.456607 5 year 0.616897 10 year 0.729184 25 year 0.878251 50 year 0.994621 100 year 1.115631 Annual Peaks sm01 3/17/2026 3:04:33 PM Page 11 Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1956 0.007 0.363 1957 0.001 0.646 1958 0.001 0.329 1959 0.001 0.439 1960 0.001 0.515 1961 0.001 0.399 1962 0.001 0.540 1963 0.001 0.742 1964 0.001 0.460 1965 0.001 0.431 1966 0.001 0.329 1967 0.001 0.372 1968 0.001 0.359 1969 0.001 0.320 1970 0.001 0.345 1971 0.003 0.355 1972 0.022 0.572 1973 0.001 0.401 1974 0.001 0.579 1975 0.001 0.409 1976 0.001 0.427 1977 0.001 0.619 1978 0.001 0.525 1979 0.001 0.596 1980 0.001 0.401 1981 0.001 0.833 1982 0.001 0.825 1983 0.001 0.824 1984 0.001 0.499 1985 0.001 0.385 1986 0.001 0.446 1987 0.001 0.483 1988 0.001 0.255 1989 0.001 0.850 1990 0.001 0.391 1991 0.004 1.014 1992 0.001 0.502 1993 0.001 1.028 1994 0.001 0.505 1995 0.001 0.673 1996 0.001 0.531 1997 0.001 0.316 1998 0.001 0.675 1999 0.001 0.427 2000 0.001 0.317 2001 0.001 0.314 2002 0.000 0.247 2003 0.001 0.512 2004 0.001 0.573 2005 0.000 0.355 2006 0.001 0.268 2007 0.001 0.506 2008 0.000 0.316 2009 0.001 0.371 2010 0.001 0.620 2011 0.001 0.303 sm01 3/17/2026 3:04:33 PM Page 12 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0218 1.0282 2 0.0073 1.0143 3 0.0038 0.8502 4 0.0029 0.8332 5 0.0011 0.8247 6 0.0011 0.8238 7 0.0011 0.7420 8 0.0011 0.6754 9 0.0011 0.6734 10 0.0011 0.6460 11 0.0011 0.6198 12 0.0011 0.6191 13 0.0011 0.5961 14 0.0011 0.5790 15 0.0011 0.5727 16 0.0011 0.5716 17 0.0010 0.5399 18 0.0010 0.5311 19 0.0010 0.5251 20 0.0010 0.5149 21 0.0010 0.5115 22 0.0010 0.5062 23 0.0010 0.5052 24 0.0010 0.5021 25 0.0010 0.4992 26 0.0010 0.4828 27 0.0010 0.4602 28 0.0010 0.4456 29 0.0010 0.4388 30 0.0010 0.4308 31 0.0010 0.4273 32 0.0010 0.4266 33 0.0010 0.4093 34 0.0010 0.4009 35 0.0010 0.4008 36 0.0010 0.3993 37 0.0010 0.3907 38 0.0010 0.3846 39 0.0010 0.3724 40 0.0010 0.3710 41 0.0010 0.3627 42 0.0010 0.3588 43 0.0010 0.3555 44 0.0010 0.3553 45 0.0010 0.3454 46 0.0010 0.3292 47 0.0010 0.3291 48 0.0009 0.3201 49 0.0008 0.3172 50 0.0008 0.3163 51 0.0008 0.3163 52 0.0008 0.3140 53 0.0006 0.3035 54 0.0005 0.2684 sm01 3/17/2026 3:04:33 PM Page 13 55 0.0004 0.2547 56 0.0003 0.2469 sm01 3/17/2026 3:04:33 PM Page 14 LID Duration Flows The Duration Matching Failed Flow(cfs)Predev Mit Percentage Pass/Fail 0.0001 25546 637968 2497 Fail 0.0001 24741 632863 2557 Fail 0.0001 23975 627758 2618 Fail 0.0001 23170 621867 2683 Fail 0.0001 22542 617351 2738 Fail 0.0001 21953 613031 2792 Fail 0.0001 21226 607926 2864 Fail 0.0001 20735 603998 2912 Fail 0.0001 20303 600268 2956 Fail 0.0001 19832 596537 3007 Fail 0.0001 19282 592217 3071 Fail 0.0001 18691 588879 3150 Fail 0.0001 18183 585541 3220 Fail 0.0001 17609 581614 3302 Fail 0.0001 17205 578668 3363 Fail 0.0001 16785 575723 3429 Fail 0.0002 16325 572188 3504 Fail 0.0002 16019 569439 3554 Fail 0.0002 15699 566690 3609 Fail 0.0002 15265 563549 3691 Fail 0.0002 14957 560996 3750 Fail 0.0002 14664 558443 3808 Fail 0.0002 14391 556087 3864 Fail 0.0002 14065 553142 3932 Fail 0.0002 13794 550982 3994 Fail 0.0002 13533 548822 4055 Fail 0.0002 13150 546073 4152 Fail 0.0002 12911 543913 4212 Fail 0.0002 12683 541949 4273 Fail 0.0002 12441 539397 4335 Fail 0.0002 12255 537433 4385 Fail 0.0002 12115 535469 4419 Fail 0.0002 11903 533506 4482 Fail 0.0002 11664 531346 4555 Fail 0.0002 11481 529579 4612 Fail 0.0002 11300 527811 4670 Fail 0.0002 11094 525651 4738 Fail 0.0002 10935 523884 4790 Fail 0.0002 10796 522313 4838 Fail 0.0002 10548 520153 4931 Fail 0.0003 10362 518583 5004 Fail 0.0003 10124 517012 5106 Fail 0.0003 9906 515048 5199 Fail 0.0003 9755 513477 5263 Fail 0.0003 9567 512103 5352 Fail 0.0003 9429 510728 5416 Fail 0.0003 9229 508961 5514 Fail 0.0003 9084 507390 5585 Fail 0.0003 8942 506016 5658 Fail 0.0003 8738 504248 5770 Fail 0.0003 8549 503070 5884 Fail 0.0003 8420 501696 5958 Fail 0.0003 8265 500125 6051 Fail 0.0003 8112 498750 6148 Fail sm01 3/17/2026 3:04:33 PM Page 15 0.0003 8004 497572 6216 Fail 0.0003 7850 496001 6318 Fail 0.0003 7725 494823 6405 Fail 0.0003 7572 493645 6519 Fail 0.0003 7454 492467 6606 Fail 0.0003 7271 491092 6754 Fail 0.0003 7167 489914 6835 Fail 0.0003 7055 488736 6927 Fail 0.0003 6912 487362 7050 Fail 0.0004 6816 486183 7132 Fail 0.0004 6721 485202 7219 Fail 0.0004 6637 483827 7289 Fail 0.0004 6549 482845 7372 Fail 0.0004 6429 481667 7492 Fail 0.0004 6293 480293 7632 Fail 0.0004 6207 479311 7722 Fail 0.0004 6122 478329 7813 Fail 0.0004 6018 477347 7931 Fail 0.0004 5901 476169 8069 Fail 0.0004 5844 475187 8131 Fail 0.0004 5787 474206 8194 Fail 0.0004 5698 473027 8301 Fail 0.0004 5637 472046 8374 Fail 0.0004 5569 471260 8462 Fail 0.0004 5471 470082 8592 Fail 0.0004 5406 469100 8677 Fail 0.0004 5327 468315 8791 Fail 0.0004 5229 467333 8937 Fail 0.0004 5152 466351 9051 Fail 0.0004 5103 465566 9123 Fail 0.0004 5011 464584 9271 Fail 0.0004 4940 463602 9384 Fail 0.0005 4885 462817 9474 Fail 0.0005 4832 461835 9557 Fail 0.0005 4768 460853 9665 Fail 0.0005 4717 460068 9753 Fail 0.0005 4644 459282 9889 Fail 0.0005 4589 458301 9986 Fail 0.0005 4548 457515 10059 Fail 0.0005 4495 456730 10160 Fail 0.0005 4440 455944 10269 Fail 0.0005 4387 454962 10370 Fail 0.0005 4343 454177 10457 Fail 0.0005 4292 453588 10568 Fail 0.0005 4247 452606 10657 Fail 0.0005 4196 451821 10767 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. sm01 3/17/2026 3:04:49 PM Page 16 Duration Flows The Duration Matching Failed Flow(cfs)Predev Mit Percentage Pass/Fail 0.0005 4196 451821 10767 Fail 0.0005 3611 444752 12316 Fail 0.0006 3112 438272 14083 Fail 0.0006 2645 432185 16339 Fail 0.0007 2233 426490 19099 Fail 0.0007 1878 421189 22427 Fail 0.0008 1611 416280 25839 Fail 0.0008 1354 411764 30410 Fail 0.0008 1158 407247 35168 Fail 0.0009 922 403124 43722 Fail 0.0009 667 399197 59849 Fail 0.0010 457 395269 86492 Fail 0.0010 270 391735 145087 Fail 0.0010 116 388201 334656 Fail 0.0011 22 383684 1744018 Fail 0.0011 21 380543 1812109 Fail 0.0012 21 377401 1797147 Fail 0.0012 20 374455 1872275 Fail 0.0012 19 371510 1955315 Fail 0.0013 19 368761 1940847 Fail 0.0013 18 366208 2034488 Fail 0.0014 18 363459 2019216 Fail 0.0014 18 361103 2006127 Fail 0.0014 17 358550 2109117 Fail 0.0015 16 356194 2226212 Fail 0.0015 16 354034 2212712 Fail 0.0016 16 351678 2197987 Fail 0.0016 14 349518 2496557 Fail 0.0016 13 347358 2671984 Fail 0.0017 12 345394 2878283 Fail 0.0017 12 343431 2861925 Fail 0.0018 12 341467 2845558 Fail 0.0018 12 339504 2829200 Fail 0.0019 11 337540 3068545 Fail 0.0019 11 335773 3052481 Fail 0.0019 11 333809 3034627 Fail 0.0020 10 332042 3320420 Fail 0.0020 10 330471 3304710 Fail 0.0021 10 328704 3287039 Fail 0.0021 10 327133 3271330 Fail 0.0021 10 325366 3253660 Fail 0.0022 10 323795 3237950 Fail 0.0022 9 322224 3580266 Fail 0.0023 9 320653 3562811 Fail 0.0023 9 319082 3545355 Fail 0.0023 9 317708 3530088 Fail 0.0024 9 316137 3512633 Fail 0.0024 9 314763 3497366 Fail 0.0025 9 313388 3482088 Fail 0.0025 9 312013 3466811 Fail 0.0025 9 310639 3451544 Fail 0.0026 9 309264 3436266 Fail 0.0026 9 307890 3421000 Fail 0.0027 8 306712 3833900 Fail sm01 3/17/2026 3:04:49 PM Page 17 0.0027 8 305337 3816712 Fail 0.0027 8 303963 3799537 Fail 0.0028 8 302785 3784812 Fail 0.0028 7 301607 4308671 Fail 0.0029 7 300232 4289028 Fail 0.0029 7 299054 4272200 Fail 0.0029 6 297876 4964600 Fail 0.0030 6 296698 4944966 Fail 0.0030 6 295519 4925316 Fail 0.0031 6 294538 4908966 Fail 0.0031 6 293359 4889316 Fail 0.0032 6 292181 4869683 Fail 0.0032 6 291200 4853333 Fail 0.0032 6 290021 4833683 Fail 0.0033 6 288843 4814050 Fail 0.0033 6 287861 4797683 Fail 0.0034 6 286683 4778050 Fail 0.0034 6 285701 4761683 Fail 0.0034 6 284720 4745333 Fail 0.0035 6 283738 4728966 Fail 0.0035 6 282756 4712600 Fail 0.0036 6 281774 4696233 Fail 0.0036 6 280793 4679883 Fail 0.0036 6 279811 4663516 Fail 0.0037 5 278829 5576580 Fail 0.0037 5 277847 5556940 Fail 0.0038 4 276865 6921625 Fail 0.0038 4 275884 6897100 Fail 0.0038 4 274902 6872550 Fail 0.0039 4 274116 6852900 Fail 0.0039 4 273135 6828375 Fail 0.0040 4 272349 6808725 Fail 0.0040 4 271367 6784175 Fail 0.0040 4 270582 6764550 Fail 0.0041 4 269796 6744900 Fail 0.0041 4 268815 6720375 Fail 0.0042 4 268029 6700725 Fail 0.0042 4 267244 6681100 Fail 0.0043 4 266262 6656550 Fail 0.0043 4 265477 6636925 Fail 0.0043 4 264691 6617275 Fail 0.0044 4 263906 6597650 Fail 0.0044 4 263120 6578000 Fail 0.0045 4 262335 6558375 Fail 0.0045 4 261549 6538725 Fail 0.0045 4 260764 6519100 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. sm01 3/17/2026 3:04:49 PM Page 18 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0.1737 acre-feet On-line facility target flow:0.2023 cfs. Adjusted for 15 min:0.2023 cfs. Off-line facility target flow:0.1149 cfs. Adjusted for 15 min:0.1149 cfs. sm01 3/17/2026 3:04:49 PM Page 19 LID Report sm01 3/17/2026 3:05:21 PM Page 20 POC 2 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #2 Total Pervious Area:1.47 Total Impervious Area:0 Mitigated Landuse Totals for POC #2 Total Pervious Area:0.44 Total Impervious Area:2.34 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #2 Return Period Flow(cfs) 2 year 0.001139 5 year 0.00195 10 year 0.002691 25 year 0.003921 50 year 0.005091 100 year 0.006521 Flow Frequency Return Periods for Mitigated. POC #2 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #2 Year Predeveloped Mitigated sm01 3/17/2026 3:06:15 PM Page 21 1956 0.008 0.000 1957 0.001 0.000 1958 0.001 0.000 1959 0.001 0.000 1960 0.001 0.000 1961 0.001 0.000 1962 0.001 0.000 1963 0.001 0.000 1964 0.001 0.000 1965 0.001 0.000 1966 0.001 0.000 1967 0.001 0.000 1968 0.001 0.000 1969 0.001 0.000 1970 0.001 0.000 1971 0.003 0.000 1972 0.025 0.000 1973 0.001 0.000 1974 0.001 0.000 1975 0.001 0.000 1976 0.001 0.000 1977 0.001 0.000 1978 0.001 0.000 1979 0.001 0.000 1980 0.001 0.000 1981 0.001 0.000 1982 0.001 0.000 1983 0.001 0.000 1984 0.001 0.000 1985 0.001 0.000 1986 0.001 0.000 1987 0.001 0.000 1988 0.001 0.000 1989 0.001 0.000 1990 0.001 0.000 1991 0.004 0.000 1992 0.001 0.000 1993 0.001 0.277 1994 0.001 0.000 1995 0.001 0.000 1996 0.001 0.000 1997 0.001 0.000 1998 0.001 0.000 1999 0.001 0.000 2000 0.001 0.000 2001 0.001 0.000 2002 0.000 0.000 2003 0.001 0.000 2004 0.001 0.000 2005 0.000 0.000 2006 0.001 0.000 2007 0.001 0.000 2008 0.001 0.000 2009 0.001 0.000 2010 0.001 0.000 2011 0.001 0.000 Ranked Annual Peaks sm01 3/17/2026 3:06:15 PM Page 22 Ranked Annual Peaks for Predeveloped and Mitigated. POC #2 Rank Predeveloped Mitigated 1 0.0245 0.2770 2 0.0082 0.0000 3 0.0042 0.0000 4 0.0033 0.0000 5 0.0012 0.0000 6 0.0012 0.0000 7 0.0012 0.0000 8 0.0012 0.0000 9 0.0012 0.0000 10 0.0012 0.0000 11 0.0012 0.0000 12 0.0012 0.0000 13 0.0012 0.0000 14 0.0012 0.0000 15 0.0012 0.0000 16 0.0012 0.0000 17 0.0012 0.0000 18 0.0012 0.0000 19 0.0012 0.0000 20 0.0012 0.0000 21 0.0012 0.0000 22 0.0012 0.0000 23 0.0012 0.0000 24 0.0012 0.0000 25 0.0012 0.0000 26 0.0012 0.0000 27 0.0012 0.0000 28 0.0012 0.0000 29 0.0012 0.0000 30 0.0012 0.0000 31 0.0012 0.0000 32 0.0012 0.0000 33 0.0012 0.0000 34 0.0012 0.0000 35 0.0012 0.0000 36 0.0012 0.0000 37 0.0012 0.0000 38 0.0012 0.0000 39 0.0012 0.0000 40 0.0011 0.0000 41 0.0011 0.0000 42 0.0011 0.0000 43 0.0011 0.0000 44 0.0011 0.0000 45 0.0011 0.0000 46 0.0011 0.0000 47 0.0011 0.0000 48 0.0011 0.0000 49 0.0009 0.0000 50 0.0009 0.0000 51 0.0009 0.0000 52 0.0009 0.0000 53 0.0007 0.0000 54 0.0005 0.0000 55 0.0004 0.0000 56 0.0003 0.0000 sm01 3/17/2026 3:06:15 PM Page 23 sm01 3/17/2026 3:06:15 PM Page 24 LID Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0001 25546 4 0 Pass 0.0001 24800 4 0 Pass 0.0001 23956 4 0 Pass 0.0001 23268 4 0 Pass 0.0001 22542 4 0 Pass 0.0001 21894 4 0 Pass 0.0001 21246 4 0 Pass 0.0001 20794 4 0 Pass 0.0001 20303 4 0 Pass 0.0001 19793 4 0 Pass 0.0001 19298 4 0 Pass 0.0001 18650 4 0 Pass 0.0001 18104 4 0 Pass 0.0002 17684 4 0 Pass 0.0002 17223 4 0 Pass 0.0002 16757 4 0 Pass 0.0002 16347 4 0 Pass 0.0002 16003 4 0 Pass 0.0002 15656 4 0 Pass 0.0002 15340 4 0 Pass 0.0002 14976 4 0 Pass 0.0002 14662 4 0 Pass 0.0002 14360 4 0 Pass 0.0002 14063 4 0 Pass 0.0002 13765 4 0 Pass 0.0002 13531 4 0 Pass 0.0002 13185 4 0 Pass 0.0002 12914 4 0 Pass 0.0002 12663 4 0 Pass 0.0002 12449 4 0 Pass 0.0002 12243 4 0 Pass 0.0002 12121 4 0 Pass 0.0002 11891 4 0 Pass 0.0003 11679 4 0 Pass 0.0003 11465 4 0 Pass 0.0003 11277 4 0 Pass 0.0003 11092 4 0 Pass 0.0003 10943 4 0 Pass 0.0003 10786 4 0 Pass 0.0003 10558 4 0 Pass 0.0003 10356 4 0 Pass 0.0003 10097 4 0 Pass 0.0003 9906 4 0 Pass 0.0003 9773 4 0 Pass 0.0003 9567 4 0 Pass 0.0003 9413 4 0 Pass 0.0003 9233 4 0 Pass 0.0003 9070 4 0 Pass 0.0003 8913 4 0 Pass 0.0003 8765 4 0 Pass 0.0003 8553 4 0 Pass 0.0003 8404 4 0 Pass 0.0003 8271 4 0 Pass sm01 3/17/2026 3:06:15 PM Page 25 0.0003 8106 4 0 Pass 0.0004 7990 4 0 Pass 0.0004 7870 4 0 Pass 0.0004 7738 4 0 Pass 0.0004 7560 4 0 Pass 0.0004 7428 4 0 Pass 0.0004 7269 4 0 Pass 0.0004 7151 4 0 Pass 0.0004 7053 4 0 Pass 0.0004 6931 4 0 Pass 0.0004 6816 4 0 Pass 0.0004 6717 4 0 Pass 0.0004 6639 4 0 Pass 0.0004 6537 4 0 Pass 0.0004 6435 4 0 Pass 0.0004 6313 4 0 Pass 0.0004 6213 4 0 Pass 0.0004 6115 4 0 Pass 0.0004 6001 4 0 Pass 0.0004 5895 4 0 Pass 0.0004 5846 4 0 Pass 0.0004 5785 4 0 Pass 0.0005 5702 4 0 Pass 0.0005 5635 4 0 Pass 0.0005 5559 4 0 Pass 0.0005 5471 4 0 Pass 0.0005 5410 4 0 Pass 0.0005 5325 4 0 Pass 0.0005 5221 4 0 Pass 0.0005 5154 4 0 Pass 0.0005 5090 4 0 Pass 0.0005 4999 4 0 Pass 0.0005 4944 4 0 Pass 0.0005 4885 4 0 Pass 0.0005 4828 4 0 Pass 0.0005 4770 4 0 Pass 0.0005 4711 4 0 Pass 0.0005 4634 4 0 Pass 0.0005 4597 4 0 Pass 0.0005 4554 4 0 Pass 0.0005 4493 4 0 Pass 0.0005 4432 4 0 Pass 0.0006 4385 4 0 Pass 0.0006 4338 4 0 Pass 0.0006 4290 4 0 Pass 0.0006 4249 4 0 Pass 0.0006 4196 4 0 Pass sm01 3/17/2026 3:06:29 PM Page 26 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0006 4196 4 0 Pass 0.0006 3611 4 0 Pass 0.0007 3110 4 0 Pass 0.0007 2641 4 0 Pass 0.0008 2231 4 0 Pass 0.0008 1881 4 0 Pass 0.0008 1608 4 0 Pass 0.0009 1352 4 0 Pass 0.0009 1163 4 0 Pass 0.0010 922 4 0 Pass 0.0010 663 4 0 Pass 0.0011 464 4 0 Pass 0.0011 269 4 1 Pass 0.0012 114 4 3 Pass 0.0012 22 4 18 Pass 0.0013 21 4 19 Pass 0.0013 21 4 19 Pass 0.0013 20 4 20 Pass 0.0014 19 4 21 Pass 0.0014 19 4 21 Pass 0.0015 18 4 22 Pass 0.0015 18 4 22 Pass 0.0016 18 4 22 Pass 0.0016 17 4 23 Pass 0.0017 16 4 25 Pass 0.0017 16 4 25 Pass 0.0018 16 4 25 Pass 0.0018 14 4 28 Pass 0.0018 13 4 30 Pass 0.0019 12 4 33 Pass 0.0019 12 4 33 Pass 0.0020 12 4 33 Pass 0.0020 12 4 33 Pass 0.0021 11 4 36 Pass 0.0021 11 4 36 Pass 0.0022 11 4 36 Pass 0.0022 10 4 40 Pass 0.0023 10 4 40 Pass 0.0023 10 4 40 Pass 0.0024 10 4 40 Pass 0.0024 10 4 40 Pass 0.0024 10 4 40 Pass 0.0025 9 4 44 Pass 0.0025 9 4 44 Pass 0.0026 9 4 44 Pass 0.0026 9 4 44 Pass 0.0027 9 4 44 Pass 0.0027 9 4 44 Pass 0.0028 9 4 44 Pass 0.0028 9 4 44 Pass 0.0029 9 4 44 Pass 0.0029 9 4 44 Pass 0.0029 9 4 44 Pass sm01 3/17/2026 3:06:30 PM Page 27 0.0030 8 4 50 Pass 0.0030 8 4 50 Pass 0.0031 8 4 50 Pass 0.0031 8 4 50 Pass 0.0032 7 4 57 Pass 0.0032 7 4 57 Pass 0.0033 7 4 57 Pass 0.0033 6 4 66 Pass 0.0034 6 4 66 Pass 0.0034 6 4 66 Pass 0.0034 6 4 66 Pass 0.0035 6 4 66 Pass 0.0035 6 4 66 Pass 0.0036 6 4 66 Pass 0.0036 6 4 66 Pass 0.0037 6 4 66 Pass 0.0037 6 4 66 Pass 0.0038 6 4 66 Pass 0.0038 6 4 66 Pass 0.0039 6 4 66 Pass 0.0039 6 4 66 Pass 0.0039 6 4 66 Pass 0.0040 6 4 66 Pass 0.0040 6 4 66 Pass 0.0041 6 4 66 Pass 0.0041 5 4 80 Pass 0.0042 5 4 80 Pass 0.0042 4 4 100 Pass 0.0043 4 4 100 Pass 0.0043 4 4 100 Pass 0.0044 4 4 100 Pass 0.0044 4 4 100 Pass 0.0045 4 4 100 Pass 0.0045 4 4 100 Pass 0.0045 4 4 100 Pass 0.0046 4 4 100 Pass 0.0046 4 4 100 Pass 0.0047 4 4 100 Pass 0.0047 4 4 100 Pass 0.0048 4 4 100 Pass 0.0048 4 4 100 Pass 0.0049 4 4 100 Pass 0.0049 4 4 100 Pass 0.0050 4 4 100 Pass 0.0050 4 4 100 Pass 0.0050 4 4 100 Pass 0.0051 4 4 100 Pass sm01 3/17/2026 3:06:30 PM Page 28 Water Quality Water Quality BMP Flow and Volume for POC #2 On-line facility volume:0.3103 acre-feet On-line facility target flow:0.3616 cfs. Adjusted for 15 min:0.3616 cfs. Off-line facility target flow:0.2054 cfs. Adjusted for 15 min:0.2054 cfs. sm01 3/17/2026 3:06:30 PM Page 29 LID Report sm01 3/17/2026 3:06:30 PM Page 30 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. sm01 3/17/2026 3:06:30 PM Page 31 Appendix Predeveloped Schematic sm01 3/17/2026 3:06:36 PM Page 32 Mitigated Schematic sm01 3/17/2026 3:06:40 PM Page 33 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1955 10 01 END 2011 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 sm01.wdm MESSU 25 Presm01.MES 27 Presm01.L61 28 Presm01.L62 31 POCsm012.dat 30 POCsm011.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 1 COPY 502 COPY 501 DISPLY 2 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 2 Basin 1 MAX 1 2 31 9 1 Basin 2 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 502 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 1 A/B, Forest, Flat 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 1 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO sm01 3/17/2026 3:06:40 PM Page 34 <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 1 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 1 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 1 0 5 2 400 0.05 0.3 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 1 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 1 0.2 0.5 0.35 0 0.7 0.7 END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 1 0 0 0 0 3 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END IWAT-PARM3 sm01 3/17/2026 3:06:40 PM Page 35 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# *** Basin 1*** PERLND 1 1.47 COPY 502 12 PERLND 1 1.47 COPY 502 13 Basin 2*** PERLND 1 1.31 COPY 501 12 PERLND 1 1.31 COPY 501 13 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 502 OUTPUT MEAN 1 1 48.4 DISPLY 2 INPUT TIMSER 1 COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS sm01 3/17/2026 3:06:41 PM Page 36 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 0.857 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 0.857 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 502 OUTPUT MEAN 1 1 48.4 WDM 502 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 END MASS-LINK END RUN sm01 3/17/2026 3:06:41 PM Page 37 Mitigated UCI File RUN GLOBAL WWHM4 model simulation START 1955 10 01 END 2011 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 sm01.wdm MESSU 25 Mitsm01.MES 27 Mitsm01.L61 28 Mitsm01.L62 30 POCsm011.dat 31 POCsm012.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 4 IMPLND 4 IMPLND 8 IMPLND 11 RCHRES 1 COPY 501 COPY 2 COPY 502 DISPLY 1 DISPLY 2 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 PGHS MAX 1 2 30 9 2 Contech CMP 3 MAX 1 2 31 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 2 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 *** 4 A/B, Pasture, Flat 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY sm01 3/17/2026 3:06:41 PM Page 38 <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 4 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 ********* 4 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 *** 4 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 4 0 5 1.5 400 0.05 0.3 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 4 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 4 0.15 0.5 0.3 0 0.7 0.4 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 4 0 0 0 0 3 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 4 ROOF TOPS/FLAT 1 1 1 27 0 8 SIDEWALKS/FLAT 1 1 1 27 0 11 PARKING/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 4 0 0 1 0 0 0 8 0 0 1 0 0 0 11 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 4 0 0 4 0 0 4 1 9 8 0 0 4 0 0 0 1 9 11 0 0 4 0 0 0 1 9 END PRINT-INFO sm01 3/17/2026 3:06:41 PM Page 39 IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 4 0 0 0 0 0 8 0 0 0 0 0 11 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 4 400 0.01 0.1 0.1 8 400 0.01 0.1 0.1 11 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 4 0 0 8 0 0 11 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 4 0 0 8 0 0 11 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Roof/Sidewalk/Ldscp*** PERLND 4 0.44 RCHRES 1 2 PERLND 4 0.44 RCHRES 1 3 IMPLND 4 0.73 RCHRES 1 5 IMPLND 8 0.3 RCHRES 1 5 PGHS*** IMPLND 11 1.31 RCHRES 1 5 PGHS*** IMPLND 11 1.31 COPY 501 15 ******Routing****** PERLND 4 0.44 COPY 2 12 IMPLND 4 0.73 COPY 2 15 IMPLND 8 0.3 COPY 2 15 PERLND 4 0.44 COPY 2 13 IMPLND 11 1.31 COPY 2 15 RCHRES 1 1 COPY 502 17 END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 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 sm01 3/17/2026 3:06:41 PM Page 40 RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** 1 Contech CMP 3 2 1 1 1 28 0 1 END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** 1 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** 1 1 0.02 0.0 0.0 0.5 0.0 END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> 1 0 4.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES FTABLE 1 91 5 Depth Area Volume Outflow1 Outflow2 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.030303 0.000000 0.000000 0.000000 0.050000 0.030303 0.000607 0.000000 0.540833 0.100000 0.030303 0.001214 0.000000 0.540833 0.150000 0.030303 0.001821 0.000000 0.540833 0.200000 0.030303 0.002428 0.000000 0.540833 0.250000 0.030303 0.003034 0.000000 0.540833 0.300000 0.030303 0.003632 0.000000 0.540833 0.350000 0.030303 0.004239 0.000000 0.540833 0.400000 0.030303 0.004846 0.000000 0.540833 0.450000 0.030303 0.005452 0.000000 0.540833 0.500000 0.030303 0.006059 0.000000 0.540833 0.588889 0.030303 0.007302 0.000000 0.540833 0.766667 0.030303 0.010141 0.000000 0.540833 0.855556 0.030303 0.011673 0.000000 0.540833 0.944444 0.030303 0.013262 0.000000 0.540833 1.033333 0.030303 0.014903 0.000000 0.540833 1.211111 0.030303 0.018316 0.000000 0.540833 1.300000 0.030303 0.020081 0.000000 0.540833 1.388889 0.030303 0.021880 0.000000 0.540833 1.477778 0.030303 0.023712 0.000000 0.540833 1.655556 0.030303 0.027465 0.000000 0.540833 1.744444 0.030303 0.029381 0.000000 0.540833 sm01 3/17/2026 3:06:41 PM Page 41 1.833333 0.030303 0.031322 0.000000 0.540833 1.922222 0.030303 0.033288 0.000000 0.540833 2.100000 0.030303 0.037283 0.000000 0.540833 2.188889 0.030303 0.039310 0.000000 0.540833 2.277778 0.030303 0.041356 0.000000 0.540833 2.366667 0.030303 0.043419 0.000000 0.540833 2.544444 0.030303 0.047594 0.000000 0.540833 2.633333 0.030303 0.049704 0.000000 0.540833 2.722222 0.030303 0.051828 0.000000 0.540833 2.811111 0.030303 0.053965 0.000000 0.540833 2.988889 0.030303 0.058274 0.000000 0.540833 3.077778 0.030303 0.060444 0.000000 0.540833 3.166667 0.030303 0.062626 0.000000 0.540833 3.255556 0.030303 0.064815 0.000000 0.540833 3.433333 0.030303 0.069221 0.000000 0.540833 3.522222 0.030303 0.071435 0.000000 0.540833 3.611111 0.030303 0.073655 0.000000 0.540833 3.700000 0.030303 0.075881 0.000000 0.540833 3.877778 0.030303 0.080350 0.000000 0.540833 3.966667 0.030303 0.082590 0.000000 0.540833 4.055556 0.030303 0.084834 0.000000 0.540833 4.144444 0.030303 0.087080 0.000000 0.540833 4.322222 0.030303 0.091581 0.000000 0.540833 4.411111 0.030303 0.093833 0.000000 0.540833 4.500000 0.030303 0.096086 0.000000 0.540833 4.588889 0.030303 0.098338 0.000000 0.540833 4.766667 0.030303 0.102842 0.000000 0.540833 4.855556 0.030303 0.105091 0.000000 0.540833 4.944444 0.030303 0.107338 0.000000 0.540833 5.033333 0.030303 0.109582 0.000000 0.540833 5.211111 0.030303 0.114059 0.000000 0.540833 5.300000 0.030303 0.116291 0.000000 0.540833 5.388889 0.030303 0.118516 0.000000 0.540833 5.477778 0.030303 0.120737 0.000000 0.540833 5.655556 0.030303 0.125157 0.000000 0.540833 5.744444 0.030303 0.127356 0.000000 0.540833 5.833333 0.030303 0.129546 0.000000 0.540833 5.922222 0.030303 0.131727 0.000000 0.540833 6.100000 0.030303 0.136058 0.000000 0.540833 6.188889 0.030303 0.138207 0.000000 0.540833 6.277778 0.030303 0.140344 0.000000 0.540833 6.366667 0.030303 0.142468 0.000000 0.540833 6.544444 0.030303 0.146673 0.000000 0.540833 6.722222 0.030303 0.150816 0.000000 0.540833 6.811111 0.030303 0.152862 0.000000 0.540833 6.988889 0.030303 0.156897 0.411624 0.540833 7.077778 0.030303 0.158884 1.367583 0.540833 7.166667 0.030303 0.160849 2.623077 0.540833 7.255556 0.030303 0.162790 4.073804 0.540833 7.522222 0.030303 0.168460 8.626212 0.540833 7.611111 0.030303 0.170292 9.896054 0.540833 7.700000 0.030303 0.172091 10.92400 0.540833 7.877778 0.030303 0.175583 12.25478 0.540833 7.966667 0.030303 0.177269 12.90964 0.540833 8.055556 0.030303 0.178910 13.44498 0.540833 8.144444 0.030303 0.180499 13.95980 0.540833 8.322222 0.030303 0.183493 14.93632 0.540833 8.411111 0.030303 0.184870 15.40137 0.540833 8.500000 0.030303 0.186113 15.85279 0.540833 8.550000 0.030303 0.186720 16.10115 0.540833 8.600000 0.030303 0.187326 16.34574 0.540833 8.650000 0.030303 0.187933 16.58672 0.540833 8.700000 0.030303 0.188540 16.82425 0.540833 8.750000 0.030303 0.189147 17.05848 0.540833 8.800000 0.030303 0.189744 17.28953 0.540833 8.850000 0.030303 0.190351 17.51753 0.540833 8.900000 0.030303 0.190958 17.74261 0.540833 8.950000 0.030303 0.191565 17.96486 0.540833 9.000000 0.030303 0.192172 18.18440 0.540833 END FTABLE 1 sm01 3/17/2026 3:06:41 PM Page 42 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 0.857 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 0.857 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** RCHRES 1 HYDR RO 1 1 1 WDM 1000 FLOW ENGL REPL RCHRES 1 HYDR O 1 1 1 WDM 1001 FLOW ENGL REPL RCHRES 1 HYDR O 2 1 1 WDM 1002 FLOW ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1003 STAG ENGL REPL COPY 2 OUTPUT MEAN 1 1 48.4 WDM 702 FLOW ENGL REPL COPY 502 OUTPUT MEAN 1 1 48.4 WDM 802 FLOW ENGL REPL COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 2 PERLND PWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 2 MASS-LINK 3 PERLND PWATER IFWO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 3 MASS-LINK 5 IMPLND IWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 5 MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 MASS-LINK 17 RCHRES OFLOW OVOL 1 COPY INPUT MEAN END MASS-LINK 17 END MASS-LINK END RUN sm01 3/17/2026 3:06:41 PM Page 43 Predeveloped HSPF Message File sm01 3/17/2026 3:06:41 PM Page 44 Mitigated HSPF Message File sm01 3/17/2026 3:06:41 PM Page 45 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 Attachment F 1001 Cooper Point Rd SW, STE 140 PMB 108 | Olympia, WA 98502 | 360.481.9784 | CHeathman@MudBayGeotech.com November 4th, 2025 Project No: 3156-THU Page 1 Subject: Site Development - Geotechnical Report 718 Yelm Ave W & 209 Cullens St SE Yelm, WA 98597 Parcel #21724140900 & #21724141001 Dear Steve Miskimens, This report presents the results of our geotechnical investigation and contains geotechnical recommendations for the site development project located at Thurston County Tax Parcels #21724140900 & #21724141001 in Yelm, WA. The analyses, conclusions, and recommendations in this report are based on the information available. These informational resources include: three (3) excavated test pits completed specifically for the subject project, one (1) Small Pilot Infiltration Test (Small PIT), published geologic information for the site and vicinity and our experience with similar geologic materials. The conditions observed in the explorations are assumed to be representative of the subsurface conditions throughout the project area. If during construction, subsurface conditions differ from those described in the explorations, we should be advised immediately so that we may reevaluate our recommendations and provide further assistance. This is an updated version of the report that supersedes all previous versions. SITE CONDITIONS AND PROJECT DESCRIPTION Parcels #21724140900 & #21724141001 consist of a total of 2.70 and 0.79 acres, respectively, in Yelm, Washington. Parcel #21724140900 has been given the situs address of 718 Yelm Ave W and Parcel #2172414100 has been given the situs address of 209 Cullens St SE. The subject parcels have been identified on the Site Location Map included as Figure 1 attached to this report. Parcel #21724140900 is located off the eastern side of Yelm Ave SE and can be accessed via a paved parking area. The parcel is currently partially developed with a professional building and 3156-THU: Parcels #21724140900 & #21724141001 Yelm, WA Page |2 parking lot within the southwestern half. The northeastern half of the parcel is undeveloped and is vegetated with various shrubbery and tall grasses. The topography of the parcel is generally flat with a slight increase in grade and elevation moving northwards. Parcel #2172414100 is located off the western side of NW Cullens Rd and can be accessed via a rudimentary gravel roadway. The parcel is currently undeveloped and vegetated with various shrubbery and tall grasses. The topography of the parcel is generally flat with a with no significant grade differences. The parcels abut each other at their northeastern and northwestern sides, respectively. The purpose of this report is to provide subsurface conditions, geotechnical recommendations and a geotechnical design infiltration rate in regard to site development within the subject parcels. The scope of the project is to develop the site with a new basketball gymnasium with the associated stormwater facilities and impervious surfaces. An underground infiltration facility is proposed at approximately 8 feet below ground surface. A proposed site plan has not been provided for our review at the time of this report. Stormwater infiltration facilities are proposed as a flow control and treatment BMP for the new impervious surface generated as part of the redevelopment. The parcel is located within the jurisdiction of the City of Yelm; therefore, the stormwater and infiltration design requirements of the 2024 Stormwater Management Manual for Western Washington need to be satisfied. To meet the requirements for that method, we performed a single (1) Small Pilot Infiltration Test (Small PIT) and performed laboratory testing on selected samples to further refine soil classification and to determine key soil index parameters such as grain size distribution and plasticity. The infiltration test was completed at approximately 8 feet below ground surface based on the assumption deep infiltration facilities will be used for treatment and flow control. The infiltration test was performed near the location of proposed stormwater facilities. SITE GEOLOGY AND SOILS As part of this project, we reviewed available geologic data and prepared a site-specific geologic map. The project vicinity geologic map is attached as Figure 2, WA DNR Geologic Map. This figure indicates the project vicinity consists of Pleistocene continental glacial drift. The DNR describes these deposits as follows: Recessional and proglacial, stratified pebble, cobble, and boulder gravel deposited in meltwater streams and their deltas; locally contains ice-contact deposits. Conditions observed at the site are generally consistent with the mapped geology at the site. 3156-THU: Parcels #21724140900 & #21724141001 Yelm, WA Page |3 In addition to the site geology, site-specific soil data made available by the United States Department of Agriculture was consulted. The USDA Soil Map is attached to this report as Figure 3. This figure suggests that the southwestern half of Parcel #21724140900 is underlain by No. 112 – Spanaway stoney sandy loam, 3 to 15 percent slopes. The northeastern half of Parcel #21724140900 and all of Parcel #21724141001 is underlain by No. 110 – Spanaway gravelly sandy loam, 0 to 3 percent slopes. The Spanaway soil series is described by the USDA as follows: Very deep, somewhat excessively draining gravelly to extremely gravelly sandy loam formed in glacial outwash across terraces and plains. The soils observed in-situ are generally consistent with the mapped soils on-site. It should be noted that the slope percentages displayed on the map are estimates and do not necessarily reflect true surface topography. SUBSURFACE EXPLORATION To characterize the surface and subsurface conditions, Mud Bay Geotechnical Services, LLC observed and logged the excavation of two (2) test pits designated TP-1-25 and TP-2-25 on May 29th, 2025. TP-1-25 was completed near the center of Parcel #21724141001. TP-2-25 was completed within the northeastern portion of Parcel #21724140900. ITP-2-25 was completed on November 2nd, 2025, just north of TP-2-25. The excavated test pits were completed from the existing ground surface at the approximate locations shown on Figure 4, Site Exploration Map. The excavated test pits completed on May 29th, 2025, were dug using a Kobelco ED150 excavator with Mud Bay Geotechnical Services, LLC personnel onsite to observe excavations, log the soils encountered in the pits, and collect samples. The excavated test pit completed on November 2nd 2025, were dug using a John Deere 85G excavator with Mud Bay Geotechnical Services, LLC personnel onsite to observe excavations, log the soils encountered in the pits, and collect samples. Samples were removed from the bottom of the pits at selected depths to observe the soil materials found throughout the test pits. The soil samples were classified visually in the field in general accordance with ASTM D2488, the Standard Practice for Description and Identification of Soils (Visual-Manual Procedure). Once transported back to the office, the samples were re-examined, and the field classifications were modified accordingly. Summary logs of the test pits are included in Appendix A. Representative samples were selected for a suite of laboratory tests. The overall soil testing program included particle-size analysis (ASTM gradation testing). The results of the laboratory tests are presented in Appendix B. Note the soil descriptions and interfaces shown on the logs are interpretive, and actual charges may 3156-THU: Parcels #21724140900 & #21724141001 Yelm, WA Page |4 be gradual. Upon completion, the test pits were backfilled to the original ground surface using spoils for the performed test pit excavations. SUBSURFACE SOIL AND GROUNDWATER CONDITIONS TP-1-25 0 to 18 inches: Moist, dark brown, topsoil and organics (TOPSOIL) 18 to 168 inches: Moist, brown, poorly graded gravel with or without sand (GP) TP-2-25 0 to 18 inches: Moist, dark brown, topsoil and organics (TOPSOIL) 18 to 168 inches: Moist, brown, poorly graded gravel with or without sand (GP) ITP-1-25 0 to 18 inches: Moist, dark brown, topsoil and organics (TOPSOIL) 18 to 156 inches: Moist, brown, poorly graded gravel with or without sand (GP) The excavated test pits performed are assumed to be representative of the project area subsurface conditions, however, the true nature of glacial deposits can be difficult to ascertain as they are highly variable units. If conditions vary significantly during construction, we should be contacted to reassess the recommendations included in this report. Groundwater was not encountered during our subsurface exploration of the site. Other geotechnical explorations conducted by Mud Bay Geotechnical Services LLC within the surrounding area indicate a seasonally high groundwater table elevation corresponding to as shallow as 12 feet below ground surface. Based on feedback from the City of Yelm, we understand that since this site is not mapped as a critical aquifer, groundwater monitoring is not required and therefore was not completed as part of our scope. FIELD MEASURED INFILTRATION TESTING As part of the geotechnical investigation, a site reconnaissance and subsurface investigation was performed between November 2nd, 2025. A single (1) Small Pilot Infiltration Test (Small PIT) was completed. This test pit, designated ITP-1-25, was excavated the day of testing to a depth near the bottom of the presumed infiltration facility. A summary of the infiltration testing geometry for the Small PIT is provided in Table 1 below. 3156-THU: Parcels #21724140900 & #21724141001 Yelm, WA Page |5 Table 1: Small PIT Geometry The infiltration test was performed on November 2nd, 2025, following the general guidelines established by the 2024 Stormwater Management Manual for Western Washington. A vertical measuring stick of 3 feet in height was placed within the center of the test pit to provide measurements within ½” accuracy. Water was introduced into the pit using a garden hose and splash plate. The pit was attempted to be filled to a minimum depth of 12 inches, and water was introduced to the pit at the highest hose raterate to attempt to maintain a water level of at least 12 inches above the base of the pit during the 6-hour pre-soak period. The depth of water was recorded at selected times during this period. A summary of the water level measurements is presented in Table 2. Table 2: ITP-1-25 Pre-Soak Water Level Measurements In ITP-1-25, the six-hour pre-soak period was concluded with a minimum water head of approximately 1.5 inches. MBGS was unable to raise the water depth of 12 inches from the available water supplies continuously throw the hose bib onsite. A series of steady state instantaneous flow measurements were recorded for the hose bib. Instantaneous flow measurements were performed using a stopwatch and recording the time required to fill up 5 gallons with water. A summary of results from the one-hour steady state period are presented in Table 3. Table 3: ITP-1-25 Steady State Measurements Small PIT Depth (in.)Top Width (in.)Top Length (in.)Basal Width (in.)Basal Length (in.)Bottom Area (sq. ft.) ITP-1-25 96 72 96 36 48 12 Small PIT Geometry Approximate Time Depth of Water (in.) 9:30 AM 0 10:30 AM 0.25 11:30 AM 0.5 12:30 PM 0.75 1:30 PM 1 2:30 PM 1.5 3:30 PM 1.5 Pre-Soak Water Level Measurements 3156-THU: Parcels #21724140900 & #21724141001 Yelm, WA Page |6 The falling head portion of the testing was not completed as part of this test pit, as MBGS was unable to reach a head of greater than 1.5 inches of water within the Small PIT following the six- hour soaking period and steady state measurements. After the steady state measurements was concluded, excavation continued below the bottom of the infiltration pit to investigate the infiltrating soil conditions, to observe the depth of saturation, to look for natural groundwater, and to look for a non-infiltrating hardpan. The immediate underlying soil conditions within ITP-1-25 consisted of moist, brown, poorly graded gravel without sand (GP), the same material observed from a depth of 18 inches to 96 inches in the test pit. This unit was seen to extend to approximately 168 inches below ground surface. Mottling was absent within the unit and the induration of the sediment was noted to be poorly indurated. A glacial hardpan unit was not encountered and no groundwater seepage was seen from the previous infiltration testing. We believe the upper on-site native soil material seen to extend between 18 to 168 inches below ground surface consists of well-draining glacial deposits. The excavation beyond the base of the test pits appears to indicate that any surface water will infiltrate vertically into the underlying, pervious strata. GEOLOGIC HAZARD ASSESSMENT Liquefaction Hazard A map of liquefaction susceptibility developed by the Washington State Department of Natural Resources (WA DNR) is attached as Figure 5, Liquefaction Hazard Map. Soil liquefaction is a phenomenon whereby saturated soil deposits temporarily lose strength and behave as a viscous fluid in response to cyclic loading. These behaviors are most common in saturated, loose, sandy soils with lesser impacts occurring in silty soils. Figure 5 indicates that the glacial outwash deposits mapped across the parcels are at very low risk of soil liquefaction. Landslide Hazard We performed a cursory review of the available online site information to determine the potential for landslide hazards at the site. The Landslide Map available from the Washington State Time of Measurement Water Depth (in.)Flow Rate (gal./min.)Flow Rate (cubic in./hr.)Cumulative Volume (gal.)Infiltration Rate (in./hr.) 3:30 PM 1.5 ------------------------------------ 3:45 PM 1.5 5.45 75537 81.75 43.71 4:00 PM 1.5 5.45 75537 163.5 43.71 4:15 PM 1.5 5.45 75537 245.25 43.71 4:30 PM 1.5 5.45 75537 327 43.71 Steady State Measurement 3156-THU: Parcels #21724140900 & #21724141001 Yelm, WA Page |7 Department of Natural Resources (WA DNR) revealed no mapped landslide deposits near the project vicinity. No indications of landslide activity, past or present, were observed during our on- site investigation nor during our review of online resources. The landslide hazard map has been omitted from this report due to this reason. The geomorphology (shape of the land) was analyzed during the site evaluation and compared to the Light Detection and Ranging images (LiDAR) from the Washington State LiDAR portal. LiDAR is a remote sensing method were light is pulsed down to the surface of the Earth and back to a sensor. This methodology enables bare earth images of the surface to be analyzed for the presence of geologic landforms. The bare earth imagery highlights the gently grading topography of the parcels and surrounding region, along with urban grading activities. We conclude the onsite landslide hazard risk to be very low. GEOTECHNICAL RECOMMENDATIONS Infiltration Rate Onsite stormwater infiltration facilities are proposed to address the excess runoff due to increased impervious surface. The infiltration will occur within the moist, brown, poorly-graded gravel with sand (GP) that was observed in the test pits, designated TP-1-25 and TP-2-25 and ITP-1-25. Using the infiltration data collected during the steady state testing, a base rate of approximately 43.71 inches per hour was determined based on the average infiltration rate recorded during the Small PIT at approximately 8 feet below existing grade. A correction factor of 0.405 was applied to this value to determine a recommended design infiltration rate of 17.70 inches per hour, which should be used in the design of infiltration facilities at the site. This correction factor assumes a moderate level of maintenance in order to reduce the potential for biofouling. We recommend that the treatment areas undergo regular inspection and maintenance so that the system is not significantly clogged due to biofouling. Based on the infiltration rates within the Small PIT, onsite soil conditions, and our experience with similar geologic conditions, we conclude that the site is very well-draining and that on-site infiltration is feasible. It should be noted that a seasonally high groundwater depth of approximately 12 feet is assumed, based on historic groundwater data collected by MBGS from the project vicinity. The infiltration facility is currently designed to be approximately 8 feet below grade. 3156-THU: Parcels #21724140900 & #21724141001 Yelm, WA Page |8 RECOMMENDED ADDITIONAL SERVICES Before construction begins, we recommend a copy of the draft plans and specifications prepared for the project are made available for review so that we can ensure that the geotechnical recommendations in this report are included in the Contract. Mud Bay Geotechnical Services, LLC is also available to provide geotechnical engineering and construction monitoring services throughout the remainder of the design and construction of the project. The integrity of the geotechnical elements of a project depend on proper site preparation and construction procedures. In addition, engineering decisions may need to be made in the field if conditions are encountered that differ from those described in this report. During the construction phase of the project, we recommend that Mud Bay Geotechnical Services, LLC be retained to review construction proposals and submittals, excavation and fill placement, drainage installation, foundation subgrade preparation, and provide recommendations for any other geotechnical considerations that may arise during construction. INTENDED USE AND LIMITATIONS This report was prepared based on observations of the surface and subsurface conditions at the site, review of geology and other information available for the site, and conversations with the property owner about the soil and surface water conditions on the property and the nature of the proposed development. The geotechnical recommendations in this report are based on the current site conditions and understanding of the proposed development as described previously. Any modification of the current property conditions or the nature of the proposed development beyond what is described in this report would render these geotechnical recommendations invalid. It should not be used, in part or in whole for other purposes without contacting Mud Bay Geotechnical Services, LLC for a review of the applicability of such reuse. We have enjoyed the opportunity to work with you and serve your geotechnical needs for the permitting phase of this project. Please contact me at your earliest convenience if you have any questions or would like to discuss any of the content of this report. Sincerely, Chris Heathman, P.E. Mud Bay Geotechnical Services, LLC 12/17/2025 Legend Approximate Site Location Figure 1: Site Map 718 Yelm Ave W & 209 Cullens St SE Yelm, WA 98597 Geotechnical Report Job #: 3156-THU Date:July, 2025 Approximate Parcel Boundary* *Parcel boundaries derived from Thurston County Show Me Everything Map Parcel #21724140900 Parcel #21724141001 Legend Figure 2: WA DNR Geologic Map 718 Yelm Ave W & 209 Cullens St SE Yelm, WA 98597 Geotechnical Report Job #: Date: Geologic Units 100k Pleistocene continental glacial drift Sources: Esri, USGS | WA State Parks GIS, Esri, HERE, Garmin, FAO, NOAA, USGS, Bureau of Land Management, EPA, NPS | Washington Geological Survey, 2019, Surface geology, 1:24,000--GIS data, November 2019: Washington Geological Survey Digital Data Series DS-10, version 3.1. N Approximate Parcel Boundary Job #: 3156-THU Date:July, 2025 Legend Figure 3: USDA Soil Map 718 Yelm Ave W & 209 Cullens St SE Yelm, WA 98597 Geotechnical Report Job #: Date: Approximate Parcel Boundary Job #: 3156-THU Date:July, 2025 Legend Approximate Test Pit Location TP-1-25 Figure 4: Site Exploration Map 718 Yelm Ave W & 209 Cullens St SE Yelm, WA 98597 Geotechnical Report Job #: Date: Approximate Parcel Boundary Job #: 3156-THU Date:July, 2025 TP-2-25 ITP-2-25 Approximate Small PIT Location Figure 5: Liquefaction Hazard Map 718 Yelm Ave W & 209 Cullens St SE Yelm, WA 98597 Geotechnical Report Job #: Date: Legend Liquefaction Susceptibility Moderate Low to Moderate Moderate to High Low High Very Low to Low Very Low Bedrock Peat Sources: Esri, USGS | WA State Parks GIS, Esri, HERE, Garmin, FAO, NOAA, USGS, Bureau of Land Management, EPA, NPS | Palmer, Stephen P.; Magsino, Sammantha L.; Bilderback, Eric L.; Poelstra, James L.; Folger, Derek S.; Niggemann, Rebecca A., 2007, Liquefaction susceptibility and site class maps of Washington State, by county: Washington Division of Geology and Earth Resources Open File Report 2004-20, [78 plates, 45 p. text]. Approximate Site Location N Job #: 3156-THU Date:July, 2025 APPENDIX A – FINAL TEST PIT LOGS Completed:Hammer Type: Hammer Weight: Groundwater Depth: Lithology 0-18": TOPSOIL Moist, dark brown, topsoil and organics. 18"-168": GP Test Pit and Boring Log Symbols Standard Penetration Slit Spoon Sampler (SPT) California Sampler Blows/1 3/4"Density Shelby Tube 0-4 Very Loose CPP Sampler 5-10 Loose StabIlized Ground water 11-24 Medium Dense Groundwater At time of Drilling 25-50 Dense Bulk/ Bag Sample REF Very Dense Gravel, Sand, Non-Plastic Silt Elastic Silts and Clays Soil Density Modifiers 2-4 Soft Blows/1 3/4"Consistency 0-1 Very Soft >60 Very Hard 5-8 Medium Stiff 9-15 Stiff 16-30 Very Stiff 31-60 Hard Project:Client:Test Pit No. 1 of 3: Site Development Steve Miskimens TP-1-25 Project Number: Contractor: Equipment: 3156-THU n/a Kobelco ED150 Address: Da t e Started:Bit Type:Diameter: Parcel #21724140900 & #21724141001 Yelm, WA 98597 5/29/2025 5/29/2025 n/a n/a Logged By: Hannah Anderson 5/29/2025 n/a n/a Hammer Drop: n/a n/a Fluid: Backfilled: Total Depth of Test Pit:Helper:Elevation: n/a n/a Existing Surface GPS Method: n/a GPS Coordinates: n/a GPS Elevation: n/a De p t h ( i n . ) Sa m p l e T y p e Sa m p l e N u m b e r Bl o w C o u n t s (b l o w s / 1 3 / 4 " ) Gr a p h i c L o g 168 inches Dr y D e n s i t y ( p c f ) Mo i s t u r e Co n t e n t ( % ) Ad d i t i o n a l T e s t Soil Group Name: modifier, color, moisture, density/consistency, grain size, other descriptors Rock Description: modifier, color, hardness/degree of concentration, bedding and joint characteristics, solutions, void conditions. S-1 @ 36": Moist, brown, poorly-graded gravel (GP). S-2 @ 72": Moist, brown, poorly-graded gravel with sand (GP). S-3 @ 108": Moist, brown, poorly-graded gravel with sand (GP). S-4 @ 144": Moist, brown, poorly-graded gravel (GP). @ 48": Sand content increasing with depth. 24" S-1 n/a 12" 36" 48" 60" 72" 84" 96" 108" 120" 132" 144" S-2 n/a S-3 n/a S-4 n/a 156" 168" Completed:Hammer Type: Hammer Weight: Groundwater Depth: Lithology 0-18": TOPSOIL Moist, dark brown, topsoil and organics. 18"-168": GP Moist, brown, poorly graded gravel with or without sand. Test Pit and Boring Log Symbols Standard Penetration Slit Spoon Sampler (SPT) California Sampler Blows/1 3/4"Density Shelby Tube 0-4 Very Loose CPP Sampler 5-10 Loose StabIlized Ground water 11-24 Medium Dense Groundwater At time of Drilling 25-50 Dense Bulk/ Bag Sample REF Very Dense TP-2-25 Project Number: Contractor: Equipment: 3156-THU n/a Kobelco ED150 Address: Da t e Started:Bit Type:Diameter: Parcel #21724140900 & #21724141001 Yelm, WA 98597 5/29/2025 Project:Client:Test Pit No. 2 of 3: Site Development Steve Miskimens n/a n/a Fluid: 5/29/2025 n/a n/a Logged By:Backfilled:Hammer Drop: Hannah Anderson 5/29/2025 n/a n/a Helper:Elevation:Total Depth of Test Pit: n/a n/a Existing Surface 168 inches GPS Method:GPS Coordinates:GPS Elevation: n/a n/a n/a De p t h ( i n . ) Sa m p l e T y p e Sa m p l e N u m b e r Bl o w C o u n t s (b l o w s / 1 3 / 4 " ) Gr a p h i c L o g Gravel, Sand, Non-Plastic Silt Elastic Silts and Clays Blows/1 3/4"Consistency Mo i s t u r e Co n t e n t ( % ) Ad d i t i o n a l T e s t Soil Group Name: modifier, color, moisture, density/consistency, grain size, other descriptors Rock Description: modifier, color, hardness/degree of concentration, bedding and joint characteristics, solutions, void conditions.Dr y D e n s i t y ( p c f ) >60 Very Hard @ 48": Sand content increasing with depth. 9-15 Stiff 16-30 Very Stiff 31-60 Hard 0-1 Very Soft 2-4 Soft 5-8 Medium Stiff Soil Density Modifiers 24" 12" 36" 48" 60" 72" 84" 96" 108" 120" 132" 144" 156" 168" Completed:Hammer Type: Hammer Weight: Groundwater Depth: Lithology 0-18": TOPSOIL Moist, dark brown, topsoil and organics. 18"-156": GP Moist, brown, poorly graded gravel with or without sand. S-1 @ 96": Moist, brown, poorly-graded gravel with sand (GP). Base of Small PIT. Test Pit and Boring Log Symbols Standard Penetration Slit Spoon Sampler (SPT) California Sampler Blows/1 3/4"Density Shelby Tube 0-4 Very Loose CPP Sampler 5-10 Loose StabIlized Ground water 11-24 Medium Dense Groundwater At time of Drilling 25-50 Dense Bulk/ Bag Sample REF Very Dense 16-30 Very Stiff 31-60 Hard >60 Very Hard 2-4 Soft 5-8 Medium Stiff 9-15 Stiff Gravel, Sand, Non-Plastic Silt Elastic Silts and Clays Blows/1 3/4"Consistency 0-1 Very Soft Mo i s t u r e Co n t e n t ( % ) Ad d i t i o n a l T e s t Soil Group Name: modifier, color, moisture, density/consistency, grain size, other descriptors Rock Description: modifier, color, hardness/degree of concentration, bedding and joint characteristics, solutions, void conditions. @ 48": Sand content increasing with depth. Soil Density Modifiers De p t h ( i n . ) Sa m p l e T y p e Sa m p l e N u m b e r Bl o w C o u n t s (b l o w s / 1 3 / 4 " ) Gr a p h i c L o g Dr y D e n s i t y ( p c f ) GPS Method:GPS Coordinates:GPS Elevation: n/a n/a n/a Helper:Elevation:Total Depth of Test Pit: n/a n/a Existing Surface 156 inches Logged By:Backfilled:Hammer Drop: Hannah Anderson 11/2/2025 n/a n/a n/a n/a Fluid: 11/2/2025 n/a n/a 3156-THU n/a John Deere 85G Address: Da t e Started:Bit Type:Diameter: Parcel #21724140900 & #21724141001 Yelm, WA 98597 11/2/2025 Project:Client:Test Pit No. 3 of 3: Site Development Steve Miskimens ITP-3-25 Project Number: Contractor: Equipment: 24" 12" 36" 48" 60" 72" 84" 96" 108" 120" 132" 144" 156" 168" S-1 n/a APPENDIX B – LABORATORY TEST RESULTS Control No: Test(s) Performed:Test(s) Performed: X Respectfully Submitted, WABO Supervising Laboratory Technician Mud Bay Geotechnical Services 1001 Copper Point Rd SW Sulfate SoundnessSieve Analysis May 29, 2025 Olympia, WA 98502 Chris Heathman June 9, 2025 25S051-02 S25-0468 Q.C. - 3165-THU As requested and authorized by the Client,MTC has performed the following test(s)on the sample number referenced above. The testing was performed in accordance with current,applicable AASHTO,ASTM,and/or WSDOT standards,which are referenced on the correlating test report pages.The results obtained in our laboratory are as detailed below and/or on the following pages: Environmental ● Geotechnical Engineering ● Special Inspection ● Non-Destructive Testing ● Materials Testing Burlington | Olympia 360.755.1990 www.mtc-inc.net Rev.5 09122023 Project:Date Received:4-Jun-25 Project #:Sampled By:Client Client:Date Tested:5-Jun-25 Source:Tested By:M. Miller Sample#:S25-0468 Control No.: Specifications D(10) =1.320 mm % Sand =12.5%Coeff. of Uniformity, CU =50.39 Sample Meets Specs ?N/A D(30) =31.659 mm Liquid Limit =n/a Plastic Limit =n/a Actual Interpolated Cumulative Cumulative Sieve Size Percent Percent Specs Specs US Metric Passing Passing Max Min Copyright Spears Engineering & Technical Services PS, 1996-98 Comments: Reviewed by: Chandler Kirk-Patterson WABO Supervising Laboratory Technician or regarding our reports is reserved pending our written approval. Sieve Report 25S051-02 Mud Bay Geotechnical Services Q.C. - 3165-THU TP-1-25: S1@ 3' GP, Poorly graded Gravel Brown 8"6"4"2"3" 1½ " 1¼ " 10 " 1" ¾" 5/ 8 " ½" 3/ 8 " ¼" #4 #8 #1 0 #1 6 #2 0 #3 0 #4 0 #5 0 #6 0 #8 0 #1 0 0 #1 4 0 #1 7 0 #2 0 0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 100.0% 0.0010.0100.1001.00010.000100.000 % P a s s i n g % P a s s i n g Particle Size (mm) Grain Size Distribution Sieve Sizes Max Specs Min Specs Sieve Results Environmental ● Geotechnical Engineering ● Special Inspection ● Non-Destructive Testing ● Materials Testing Burlington | Olympia 360.755.1990 www.mtc-inc.net Rev.5 09122023 Control No: Test(s) Performed:Test(s) Performed: X Respectfully Submitted, WABO Supervising Laboratory Technician Atterberg Limits Specific Gravity of Soils Moisture Content Cation Exchange Capacity Specific Gravity, Coarse Specific Gravity, Fine Hydrometer Analysis Proctor Sand Equivalent Fracture Count LA Abrasion See Attached Report WSDOT Degradation Bulk Density & Voids Chandler Kirk-Patterson If you have any questions concerning the test results,the procedures used,or if we can be of any further assistance please call the number below and ask to speak with your Project Manager or the Laboratory Manager. Olympia, WA 98502 Chris Heathman June 9, 2025 25S051-02 S25-0469 Q.C. - 3165-THU As requested and authorized by the Client,MTC has performed the following test(s)on the sample number referenced above. The testing was performed in accordance with current,applicable AASHTO,ASTM,and/or WSDOT standards,which are referenced on the correlating test report pages.The results obtained in our laboratory are as detailed below and/or on the following pages: Client: Sample #: Date: Project: Attn: Revised On:Date sampled: Environmental ● Geotechnical Engineering ● Special Inspection ● Non-Destructive Testing ● Materials Testing Burlington | Olympia 360.755.1990 www.mtc-inc.net Rev.5 09122023 Project:Date Received:4-Jun-25 Project #:Sampled By:Client Client:Date Tested:5-Jun-25 Source:Tested By:M. Miller Sample#:S25-0469 Control No.: Specifications D(10) =0.672 mm % Sand =19.4%Coeff. of Uniformity, CU =47.88 Sample Meets Specs ?N/A D(30) =9.044 mm Liquid Limit =n/a Plastic Limit =n/a Actual Interpolated Cumulative Cumulative Sieve Size Percent Percent Specs Specs US Metric Passing Passing Max Min Copyright Spears Engineering & Technical Services PS, 1996-98 Comments: Reviewed by: Chandler Kirk-Patterson WABO Supervising Laboratory Technician Sieve Report 25S051-02 Mud Bay Geotechnical Services Q.C. - 3165-THU TP-1-25: S2@ 6' GP, Poorly graded Gravel with Sand Brown All results apply only to actual locations and materials tested.As a mutual protection to clients,the public and ourselves,all reports are submitted as the confidential property of clients,and authorization for publication of statements,conclusions or extracts from or regarding our reports is reserved pending our written approval. 8"6"4"2"3" 1½ " 1¼ " 10 " 1" ¾" 5/ 8 " ½" 3/ 8 " ¼" #4 #8 #1 0 #1 6 #2 0 #3 0 #4 0 #5 0 #6 0 #8 0 #1 0 0 #1 4 0 #1 7 0 #2 0 0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 100.0% 0.0010.0100.1001.00010.000100.000 % P a s s i n g % P a s s i n g Particle Size (mm) Grain Size Distribution Sieve Sizes Max Specs Min Specs Sieve Results Environmental ● Geotechnical Engineering ● Special Inspection ● Non-Destructive Testing ● Materials Testing Burlington | Olympia 360.755.1990 www.mtc-inc.net Rev.5 09122023 Control No: Test(s) Performed:Test(s) Performed: X Respectfully Submitted, WABO Supervising Laboratory Technician Mud Bay Geotechnical Services 1001 Copper Point Rd SW Sulfate SoundnessSieve Analysis May 29, 2025 Olympia, WA 98502 Chris Heathman June 9, 2025 25S051-02 S25-0470 Q.C. - 3165-THU As requested and authorized by the Client,MTC has performed the following test(s)on the sample number referenced above. The testing was performed in accordance with current,applicable AASHTO,ASTM,and/or WSDOT standards,which are referenced on the correlating test report pages.The results obtained in our laboratory are as detailed below and/or on the following pages: Environmental ● Geotechnical Engineering ● Special Inspection ● Non-Destructive Testing ● Materials Testing Burlington | Olympia 360.755.1990 www.mtc-inc.net Rev.5 09122023 Project:Date Received:4-Jun-25 Project #:Sampled By:Client Client:Date Tested:5-Jun-25 Source:Tested By:M. Miller Sample#:S25-0470 Control No.: Specifications D(10) =0.717 mm % Sand =15.3%Coeff. of Uniformity, CU =31.07 Sample Meets Specs ?N/A D(30) =9.327 mm Liquid Limit =n/a Plastic Limit =n/a Actual Interpolated Cumulative Cumulative Sieve Size Percent Percent Specs Specs US Metric Passing Passing Max Min Copyright Spears Engineering & Technical Services PS, 1996-98 Comments: Reviewed by: Chandler Kirk-Patterson WABO Supervising Laboratory Technician or regarding our reports is reserved pending our written approval. Sieve Report 25S051-02 Mud Bay Geotechnical Services Q.C. - 3165-THU TP-1-25: S3 @ 9' GP, Poorly graded Gravel with Sand Brown 8"6"4"2"3" 1½ " 1¼ " 10 " 1" ¾" 5/ 8 " ½" 3/ 8 " ¼" #4 #8 #1 0 #1 6 #2 0 #3 0 #4 0 #5 0 #6 0 #8 0 #1 0 0 #1 4 0 #1 7 0 #2 0 0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 100.0% 0.0010.0100.1001.00010.000100.000 % P a s s i n g % P a s s i n g Particle Size (mm) Grain Size Distribution Sieve Sizes Max Specs Min Specs Sieve Results Environmental ● Geotechnical Engineering ● Special Inspection ● Non-Destructive Testing ● Materials Testing Burlington | Olympia 360.755.1990 www.mtc-inc.net Rev.5 09122023 Control No: Test(s) Performed:Test(s) Performed: X Respectfully Submitted, WABO Supervising Laboratory Technician Atterberg Limits Specific Gravity of Soils Moisture Content Cation Exchange Capacity Specific Gravity, Coarse Specific Gravity, Fine Hydrometer Analysis Proctor Sand Equivalent Fracture Count LA Abrasion See Attached Report WSDOT Degradation Bulk Density & Voids Chandler Kirk-Patterson If you have any questions concerning the test results,the procedures used,or if we can be of any further assistance please call the number below and ask to speak with your Project Manager or the Laboratory Manager. Olympia, WA 98502 Chris Heathman June 9, 2025 25S051-02 S25-0471 Q.C. - 3165-THU As requested and authorized by the Client,MTC has performed the following test(s)on the sample number referenced above. The testing was performed in accordance with current,applicable AASHTO,ASTM,and/or WSDOT standards,which are referenced on the correlating test report pages.The results obtained in our laboratory are as detailed below and/or on the following pages: Client: Sample #: Date: Project: Attn: Revised On:Date sampled: Environmental ● Geotechnical Engineering ● Special Inspection ● Non-Destructive Testing ● Materials Testing Burlington | Olympia 360.755.1990 www.mtc-inc.net Rev.5 09122023 Project:Date Received:4-Jun-25 Project #:Sampled By:Client Client:Date Tested:5-Jun-25 Source:Tested By:G. Dudley Sample#:S25-0471 Control No.: Specifications D(10) =1.703 mm % Sand =12.4%Coeff. of Uniformity, CU =21.36 Sample Meets Specs ?N/A D(30) =13.833 mm Liquid Limit =n/a Plastic Limit =n/a Actual Interpolated Cumulative Cumulative Sieve Size Percent Percent Specs Specs US Metric Passing Passing Max Min Copyright Spears Engineering & Technical Services PS, 1996-98 Comments: Reviewed by: Chandler Kirk-Patterson WABO Supervising Laboratory Technician Sieve Report 25S051-02 Mud Bay Geotechnical Services Q.C. - 3165-THU TP-1-25: S4 @ 12' GP, Poorly graded Gravel Brown All results apply only to actual locations and materials tested.As a mutual protection to clients,the public and ourselves,all reports are submitted as the confidential property of clients,and authorization for publication of statements,conclusions or extracts from or regarding our reports is reserved pending our written approval. 8"6"4"2"3" 1½ " 1¼ " 10 " 1" ¾" 5/ 8 " ½" 3/ 8 " ¼" #4 #8 #1 0 #1 6 #2 0 #3 0 #4 0 #5 0 #6 0 #8 0 #1 0 0 #1 4 0 #1 7 0 #2 0 0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 100.0% 0.0010.0100.1001.00010.000100.000 % P a s s i n g % P a s s i n g Particle Size (mm) Grain Size Distribution Sieve Sizes Max Specs Min Specs Sieve Results Environmental ● Geotechnical Engineering ● Special Inspection ● Non-Destructive Testing ● Materials Testing Burlington | Olympia 360.755.1990 www.mtc-inc.net Rev.5 09122023 Attachment G (Placeholder) Attachment H PLAN VIEW 0° VARIES MINIMUM DEPTH PER TABLE RIM OUTLET BASE SLAB THICKNESS 2'-0" MAX 4" VARIES ELEVATION VIEW WALL THICKNESS FALSE FLOOR SUPPORT SPACER CONCRETE FALSE FLOOR INLET/BYPASS ASSEMBLY Ø6'-0" TOP SLAB & COVER NOT SHOWN IN THIS VIEW FOR CLARITY INLET Ø36" ACCESS COVER INLET CHAMBER 180° 0'-4" MIN TO 1'-0" MAX COVER (SEE NOTE 1.B) Ø24" MAX, PIPE OUTLETØ24" MAX, PIPE INLET 2.9' DROP RECOMMENDED, MIN = OUTLET DIAMETER + 4" 24" PerkFilter ® CARTRIDGES 24" PerkFilter ® CARTRIDGES TOP SLAB THICKNESS BASE SECTION CONCRETE FALSE FLOOR.OUTLET INLET TOP SLAB INLET/BYPASS MODULE. PERKFILTERTM CARTRIDGE. BOLTED & GASKETED ACCESS COVER/HATCH, STANDARD. ALTERNATE COVERS & GRATED INLET OPTIONS AVAILABLE. ISOMETRIC VIEW RISER SECTION AS REQUIRED. Media Filtration Ph: 800.579.8819 | www.oldcastleinfrastructure.com/stormwater THI S DOC UMENT IS THE P ROPERTY OF OLD CASTLE INFRASTRU CTUR E, IN C. IT I S CO N FI DEN T I A L, S UBM I T TED F O R R E F ER E N CE P U RPO SES O NLY AN D S H ALL N OT BE U S E D I N AN Y W AY I N J UR I OU S T O T H E I N T E REST S O F , O R WITHOUT THE WRITTEN PERMISSI ON OF OLDCASTLE INFRASTRUCTURE, INC. COPYRIGHT © 2023 OLDCASTLE INFRASTRUCTURE, INC. ALL RIGHTS RESERVED. SHEET NAME REVISION SHEET REV DATE - PerkFilter® Manhole CUSTOMER PROJECT NAME - - - (STANDARD) 1 OF 1Specifier Drawing PFMH-72-24 Ø72" with 24" Cartridges MINIMUM DEPTH Outlet Pipe Size Minimum Rim to Outlet Depth Ø6"5.58' Ø8"5.83' Ø10"6.08' Ø12"6.33' Ø15"6.58' Ø18"6.83' Ø21"7.08' Ø24"7.33' PERFORMANCE SPECIFICATIONS Peak Treatment Capacities: 1 NJDEP 80% Removal, 75 micron 136 gpm / 0.303 cfs WA Ecology GULD - Basic & Phosphorus 68 gpm / 0.151 cfs SITE SPECIFIC DATA Structure ID Treatment Flow Rate (gpm/cfs) Peak Flow Rate (cfs) Rim Elevation Pipe Data Pipe Size Pipe Type Invert Elevation Outlet Notes: Pipe Location Inlet 6.90 cfsMax. Bypass Capacity Max. Cartridge Quantity 5 1. Contact Oldcastle for alternative treatment and peak flow capacities. Cartridge Quantity - - - - --- - - ---- - NOTES: 1.DESIGN LOADINGS: A.AASHTO HS-20-44 (WITH IMPACT) B.DESIGN SOIL COVER: 1'-0" MAXIMUM C.ASSUMED WATER TABLE: BELOW INVERT. D.LATERAL EARTH PRESSURE: 45 PCF (DRAINED) E.LATERAL LIVE LOAD SURCHARGE: 80 PSF (APPLIED TO 8'-0" BELOW GRADE) F.NO LATERAL SURCHARGE FROM ADJACENT BUILDINGS, WALLS, PIERS, OR FOUNDATIONS. 2.CONCRETE 28-DAY MINIMUM COMPRESSIVE STRENGTH: 5,000 PSI MINIMUM. 3.REINFORCING: REBAR, ASTM A615/A706, GRADE 60 4.CEMENT: ASTM C150 5.REQUIRED ALLOWABLE SOIL BEARING CAPACITY: 2,500 PSF 6.REFERENCE STANDARD: A.ASTM C 478 B.ASTM C 497 7.THIS STRUCTURE IS DESIGNED TO THE PARAMETERS NOTED HEREIN. ENGINEER-OF-RECORD SHALL VERIFY THAT NOTED PARAMETERS MEET OR EXCEED PROJECT REQUIREMENTS. IF DESIGN PARAMETERS ARE INCORRECT, REVIEWING ENGINEER/AUTHORITY SHALL NOTIFY OLDCASTLE INFRASTRUCTURE UPON REVIEW OF THIS SUBMITTAL. 8.OVERSIZED HOLES TO ACCOMMODATE SPECIFIC PIPE TYPE MUST BE CONCENTRIC TO PIPE ID. AFTER PIPES ARE INSTALLED, ALL ANNULAR SPACES SHALL BE FILLED WITH A MINIMUM OF 3,000 PSI CONCRETE FOR FULL THICKNESS OF PRECAST WALLS. PIPES ARE TO BE FLUSH WITH THE INSIDE SURFACE OF THE CONCRETE STRUCTURE. 9.CONTRACTOR RESPONSIBLE TO VERIFY ALL SIZES, LOCATIONS, AND ELEVATIONS OF OPENINGS. 10.CONTRACTOR RESPONSIBLE TO ENSURE ADEQUATE BEARING SURFACE IS PROVIDED (I.E. COMPACTED AND LEVEL PER PROJECT SPECIFICATIONS). 11.SECTION HEIGHTS, SLAB/WALL THICKNESSES, AND KEYWAYS ARE SUBJECT TO CHANGE AS REQUIRED FOR SITE REQUIREMENTS AND/OR DUE TO PRODUCT AVAILABILITY AND PRODUCTION FACILITY CONSTRAINTS. 12.FOR SITE SPECIFIC DRAWINGS WITH DETAILED STRUCTURE DIMENSIONS AND WEIGHTS, PLEASE CONTACT OLDCASTLE INFRASTRUCTURE. 13.MAXIMUM PICK WEIGHTS: A.TOP SLAB: XX,XXX LBS B.RISER: XX,XXX LBS C.BASE: XX,XXX LBS* (* COMBINED WEIGHT OF BASE INCLUDES FALSE FLOOR, AND PRODUCT INTERNALS.) 14.INTERNALS SHALL CONSIST OF CARTRIDGES, INLET/BYPASS ASSEMBLIES, FALSE FLOOR AND FALSE FLOOR SUPPORT SPACERS.