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20250327 Rpt (TIR) 2220348.10 (combined) Civil Engineers ● Structural Engineers ● Landscape Architects ● Community Planners ● Land Surveyors Stormwater Report PREPARED FOR: Matt Lewis Garrette Custom Homes, Inc. 4802 Tacoma Mall Boulevard Tacoma, WA 98409 PROJECT: The Reserve at Palisades Yelm, Washington 2220348.10 PREPARED BY: Allyson Burket Project Engineer REVIEWED BY: Michael C. Hager, PE Project Engineer J. Matthew Weber, PE Principal DATE: March 2025 Stormwater Report PREPARED FOR: Matt Lewis Garrette Custom Homes, Inc. 4802 Tacoma Mall Boulevard Tacoma, WA 98409 PROJECT: The Reserve at Palisades Yelm, Washington 2220348.10 PREPARED BY: Allyson Burket Project Engineer REVIEWED BY: Michael C. Hager, PE Project Engineer J. Matthew Weber, PE Principal DATE: March 2025 I hereby state that this Stormwater Report for The Reserve at Palisades project has been prepared by me or under my supervision and meets the standard of care and expertise that is usual and customary in this community for professional engineers. I understand that City of Yelm does not and will not assume liability for the sufficiency, suitability, or performance of drainage facilities prepared by me. 03/27/2025 Stormwater Report The Reserve at Palisades 2220348.10 Table of Contents Section Page 1.0 Project Overview ............................................................................................................................ 1 2.0 Summary of Minimum Requirements .......................................................................................... 1 2.1 MR 1 – Preparation of Stormwater Site Plans .................................................................... 1 2.2 MR 2 - Construction Stormwater Pollution Prevention ....................................................... 1 2.3 MR 3 – Source Control of Pollution ..................................................................................... 1 2.4 MR 4 – Preservation of Natural Drainage Systems and Outfalls ........................................ 1 2.5 MR 5 – Onsite Stormwater Control ..................................................................................... 2 2.6 MR 6 – Runoff Treatment ................................................................................................... 2 2.7 MR 7 – Flow Control ........................................................................................................... 2 2.8 MR 8 – Wetlands Protection ............................................................................................... 2 2.9 MR 9 – Basin/Watershed Planning ..................................................................................... 2 2.10 MR 10 – Operation and Maintenance ................................................................................. 2 3.0 Existing Conditions ....................................................................................................................... 3 3.1 Soils Reports ....................................................................................................................... 3 4.0 Wells and Septic Systems ............................................................................................................. 3 5.0 Fuel Tanks ...................................................................................................................................... 3 6.0 Sub-Basin Description................................................................................................................... 4 7.0 Analysis of the 100-Year Flood ..................................................................................................... 4 8.0 Aesthetic Considerations for Facilities ....................................................................................... 4 9.0 Facility Sizing and Downstream Analysis ................................................................................... 4 9.1 Conveyance ........................................................................................................................ 4 9.2 Treatment ............................................................................................................................ 4 9.3 Flow Control ........................................................................................................................ 5 9.4 Roof Runoff ......................................................................................................................... 5 9.5 Downstream Drainage ........................................................................................................ 5 10.0 Covenants Dedications, Easements ............................................................................................ 6 11.0 Property Owners Association Articles of Incorporation ............................................................ 6 12.0 Conclusion ...................................................................................................................................... 6 Stormwater Report The Reserve at Palisades 2220348.10 Appendices Appendix A Exhibits A-1 ............Vicinity Map A-2 ............Existing Conditions A-3 ............Developed Conditions A-4 ............NRCS Soil Map A-5 ............FEMA 100-Year Flood Plain Map Appendix B Facility Sizing B-1 ............Basin Map B-2 ............WWHM Report B-3 ............Conveyance Calculations Appendix C Geotechnical Report GeoResources, LLC October 10, 2024 Appendix D Existing Conditions D-1 ............Palisades West Final Storm Drainage Report D-2 ............Existing Well and Septic Stormwater Report The Reserve at Palisades 1 2220348.10 1.0 Project Overview The following hydrology report summarizes the storm drainage analysis and design for a 39-lot development located at 15036 State Route (SR) 507 SE in Yelm, Thurston County, Washington. The land is currently a 9.71-acre property. The project includes the addition of 39 residential lots for single-family homes, a new roadway and sidewalks, sewer, water services, and stormwater facilities to treat and dispose of the project's stormwater. The proposed roadway features and utilities will be extended from Palisades Street SE. The 9.71-acre site is located in Section 25, Township 17 North, Range 01 East, W.M. The Thurston County tax parcel number associated with the project is 21725130200. Runoff from the project will be conveyed to a stormwater filter vault and then directed to the onsite infiltration pond. The existing wet pond used to control runoff from the neighboring property, Palisades West, will be removed and replaced with the proposed infiltration pond. The proposed pond and stormwater filter have been sized to treat runoff from both The Reserve at Palisades and the Palisades West developments. The proposed project will connect to the existing storm network within Palisades Street SE and replace the existing storm outlet with a stormwater filter vault that drains to the infiltration pond. The increased stormwater runoff resulting from the addition of impervious area will be treated and infiltrated in accordance with the 2024 Washington State Department of Ecology (DOE) Stormwater Management Manual for Western Washington (S WMMWW). 2.0 Summary of Minimum Requirements This project is subject to the SWMMWW and is a new development that will add more than 10,000 square feet of impervious surfaces; therefore, all Minimum Requirements (MR) apply to this project. 2.1 MR 1 – Preparation of Stormwater Site Plans This report and the project plans represent the Stormwater Site Plan for this project and satisfy MR 1. 2.2 MR 2 - Construction Stormwater Pollution Prevention A Construction Stormwater Pollution Prevention Plan (SWPPP) has been prepared under a separate cover. 2.3 MR 3 – Source Control of Pollution Pollution source control will be provided for the site by treating the runoff from pollution generating surfaces with a StormFilter vault. The residential roads should be maintained and cleaned of debris, garbage, and sediment, as required. The Construction SWPPP provides details on the control of pollution during construction. 2.4 MR 4 – Preservation of Natural Drainage Systems and Outfalls The project proposes to retain and infiltrate all stormwater runoff within the developed conditions. There are no natural drainage systems or outfalls to preserve. Stormwater Report The Reserve at Palisades 2 2220348.10 2.5 MR 5 – Onsite Stormwater Control This project will meet the Low Impact Development (LID) Performance Standard. This standard requires stormwater discharging from the developed site to match pre-developed discharge rates from 8% of the 2-year peak flow to 50% of the 2-year peak flow. For the developed conditions of The Reserve at Palisades, no stormwater will discharge from the site. Instead, 100% will be infiltrated via the proposed infiltration pond. The onsite soils have a design infiltration rate of 20 inches per hour, as calculated by GeoResources. Runoff will be retained onsite through treatment systems and infiltration facilities. Refer to Appendix B-2 for the site’s pre-developed and developed flow rates. Refer to Section 9.0 for facility sizing. Additionally, all landscaped areas will have amended soils applied per the post construction soil quality and depth BMP T5.13. 2.6 MR 6 – Runoff Treatment Over 5,000 square feet of pollution generating impervious surface (PGIS) will be added as part of these improvements; therefore, runoff treatment is required for this site. An infiltration pond will replace the existing wet pond on the site’s northeast corner and will infiltrate stormwater that has been treated through the site’s stormwater filter vault. The vault has been sized to treat runoff from both the project site and Palisades West, updating the treatment method for the existing development. Refer to Section 10.0 for facility sizing. 2.7 MR 7 – Flow Control The project exceeds the thresholds for new development projects and must provide flow control . Proposed flow control is achieved with the use of an infiltration pond that will infiltrate 100% of runoff. The pond will also infiltrate 100% of the runoff from Palisades West that is currently being sent to the wet pond. Refer to Section 9.0 for facility sizing. 2.8 MR 8 – Wetlands Protection To our knowledge, no wetlands are located on or adjacent to the site. 2.9 MR 9 – Basin/Watershed Planning To our knowledge, no basin plans exist for the site. The entire city of Yelm and its urban growth area are identified as a highly susceptible critical aquifer recharge area. Treatment of stormwater prior to entering the infiltration pond is proposed via a StormFilter vault. 2.10 MR 10 – Operation and Maintenance The stormwater system for roadway improvements will be publicly owned and maintained. The City of Yelm shall be responsible for the operation and maintenance of the public stormwater facilities. Operation and maintenance for drainage facilities constructed for each lot shall be the responsibility of the individual owner. Stormwater Report The Reserve at Palisades 3 2220348.10 3.0 Existing Conditions The existing site is primarily covered with shrubbery and grass, with conifers along the property line and north portion of the site. The topography slopes north to SR 507, with slopes ranging from 0% to 20%. An abandoned house sits on the northern portion of the property. A wet pond/infiltration pond on the site’s northeast corner is currently used for stormwater management by the development, Palisades West, east of the site. Palisades West is a 24-lot housing development with open space tracts and approximately 1,500 linear feet of roadway. A storm report written January 9, 2009, notes the assumed basin areas and land cover for the site (see Appendix D-1). Per the report, all roof runoff is routed to individual onsite drywells. Runoff from the existing driveways, roadway, and sidewalks are collected in the wet pond for treatment and storage. The basin areas noted in the report were used to determine the amount of runoff generated by Palisades West that will be collected in the proposed infiltration pond. 3.1 Soils Reports Site soils are identified by the Natural Resources Conservation Service (NRCS) Web Soil Survey as Alderwood gravelly sandy loam and Everett very gravelly sandy loam. GeoResources, LLC conducted a site investigation to confirm subsurface soil conditions and establish a design infiltration rate. Soil test holes were dug in the vicinity of the proposed infiltration basin of the project and observations confirm that the soil types match the soil description. The seasonal high groundwater elevation was estimated to be 349 feet. A soil log map showing the location of the test holes is included in the geotechnical report. The report recommends a design infiltration rate of 20 inches per hour for facilities within the site’s northeast corner. Refer to Appendix C for the complete GeoResources report. 4.0 Wells and Septic Systems An existing septic tank is located near the north end of the property. The septic tank and drain field will be decommissioned during construction, per Thurston County health department standards. An abandoned well is located under the existing wet pond, near the site’s northeast corner. The Palisades West development noted that the well was to be abandoned in accordance with Department of Ecology standards in 2009. The Reserve at Palisades plans note for the contractor to verify and decommission the well if, needed. Refer to Appendix D-2 for the existing septic and well locations. Each lot will be served by the City of Yelm STEP collection system. The holding tank will be maintained by the City and pumped on a regular basis. Domestic water will be provided by the City of Yelm water distribution system. 5.0 Fuel Tanks To the best of our knowledge, no known fuel tanks exist on the site. Stormwater Report The Reserve at Palisades 4 2220348.10 6.0 Sub-Basin Description From review of site topography, it does not appear that offsite runoff is tributary to the site from the south or west. There is a single basin for the developed conditions, which will direct stormwater runoff to the proposed infiltration pond along Palisades Street SE. The basin includes the proposed site, 0.40 acre of SR 507 right-of-way, and the existing Palisades West development. Refer to Appendix A-3 for the Developed Conditions Map. 7.0 Analysis of the 100-Year Flood Federal Emergency Management Agency (FEMA) mapping does not indicate flooding in the immediate area. Refer to the exhibit in Appendix A-5. 8.0 Aesthetic Considerations for Facilities The proposed infiltration facility will be located within a stormwater tract. The facility is designed with a maximum storage depth of 5 feet and 3:1 side slopes. Landscaping plans will provide additional foliage around the facility. 9.0 Facility Sizing and Downstream Analysis The stormwater system was sized and analyzed using the latest edition of the Western Washington Hydrology Model (WWHM) continuous modeling software. A conservative infiltration rate of 20 inches per hour was used for design calculations. Proposed impervious surfaces associated with the proposed roads were calculated based on the site plan layout. 9.1 Conveyance The proposed conveyance system consists of a series of new catch basins, pipe reaches, an interceptor swale, and outfalls that collect runoff from the project site and discharge to the infiltration pond. The piped conveyance system is designed to convey a minimum of the 25-year, 24-hour design runoff event. The most limiting storm pipe within The Reserve at Palisades is located at the bottom of Palisades Street SE. It conveys runoff from both the proposed project site and the existing housing development, Palisades West, to the pond. The 25-year flow for both sites was calculated using WWHM and found to be 10.4 cfs. The existing 12-inch pipe, which outlets into the wet pond, will be replaced with a 24-inch CPEP with a minimum slope of 1.0% to provide adequate capacity. Runoff from the north hillside will be conveyed to the pond via an interceptor swale. The swale has been sized according to the DOE Stormwater Manual to contain the 10-year peak flowrate generated by the hill. Refer to Appendix B-3 for conveyance system calculations. 9.2 Treatment Basic treatment will be provided via a media filter vault with 28 PhosphoSorb cartridges located prior to the infiltration pond. The structure has been sized to treat runoff from The Reserve at Palisades and the existing Palisades West neighborhood. The offline standard flow rate per WWHM is 0.7792 cfs or 350 gpm (see Appendix B-2). The treatment rate per cartridge is 12.53 gpm, therefor, the total treatment capacity for the facility is 350.84 gpm, which exceeds the required rate. Stormwater Report The Reserve at Palisades 5 2220348.10 9.3 Flow Control Flow control will be provided by fully infiltrating stormwater runoff from the site through an infiltration pond. The pond will be 5.0 feet deep with a minimum bottom area of 8,500 square feet and a total volume of approximately 1,700 cubic yards. It will be constructed in the open space in Tract F, where an existing combined wet and infiltration pond for Palisades West is located. The bottom of the proposed pond’s elevation is 354 feet, which is 5 feet above the estimated seasonal high groundwater of 349 feet (see Appendix C). The pond will be located adjacent to SR 507. A portion of the highway, approximately 257 lineal feet of the northeast-bound lane, will sheet flow into the proposed pond. A culvert located approximately 120 feet upstream limits the amount of SR 507 draining to the pond. This culvert drains to a ditch on the north side of SR 507. Runoff generated along the north hillside of the site will be intercepted by a swale and will drain into the pond. The current area from the Palisades West development draining to the existing wet pond will also drain to the proposed infiltration pond through the existing storm network under Palisades Street SE. This area includes Palisades Street SE, sidewalks, and driveways. Basin areas for the neighboring development were obtained from the Palisades West storm report. Below is a summary of the contributing areas to the pond. Infiltration Basin Summary Road (ac) Sidewalk (ac) Driveways (ac) Roof (ac) Pond (ac) Pervious (ac) Total (ac) The Reserve at Palisades 1.45 0.18 0.60 2.42 - 3.56 8.21 Palisades West* 1.46 0.16 0.28 - - 1.93 3.83* SR 507 Bypass WQ Structure 0.11 0.02 - - 0.38 0.95 1.46 *Areas per Basin A in Table 1 of the Palisades West Final Storm Drainage Report (Appendix D-1). Excludes roof areas that drain to on-lot drywells. The basin is sized in accordance with the SWMMWW and provides the required storage volume. Refer to Appendix B-1 for the site Basin Map. 9.4 Roof Runoff Stormwater for the roof areas will be directed to the site’s infiltration pond through the site’s network of storm pipes and catch basins. 9.5 Downstream Drainage Runoff for the site is proposed to be fully infiltrated within the pond. In the unlikely event of the pond overflowing, the surface water would need to reach an elevation of 361 feet, 2 feet above the pond’s proposed freeboard, to escape the site. There are currently no culverts in the area that would allow water to drain under SR 507 or Palisades Street SE. Instead, water would most likely flow northeast along the SR 507 shoulder to an existing catch basin approximately 330 feet from the site. Stormwater Report The Reserve at Palisades 6 2220348.10 10.0 Covenants Dedications, Easements Public right-of-way will be created for this project. Along with the right-of-way, 10-foot joint utility easements and 2-foot private storm conveyance easements will be provided behind each side of the road. The stormwater facilities for the right-of-way improvements shall be owned and maintained by the homeowners’ association. A maintenance agreement should be executed to ensure future maintenance of the facilities. 11.0 Property Owners Association Articles of Incorporation Not applicable. 12.0 Conclusion The proposed project involves site improvements associated with a 39-lot development. The project includes clearing, grading, erosion control, utility improvements, and stormwater management facilities. The site, as proposed, will meet the requirements of the 2024 Department of Ecology Stormwater Management Manual for Western Washington (SWMMWW). This report and associated plans have been prepared within the guidelines established by City of Yelm for stormwater management. This analysis is based on data and records either supplied to or obtained by AHBL . These documents are referenced within the text of the analysis. The analysis has been prepared using procedures and practices within the standard accepted practices of the industry. AHBL, Inc. Allyson Burket Project Engineer AB/lsk March 2025 Q:\2022\2220348\WORDPROC\Reports\20250327 Rpt (TIR) 2220348.10.docx Stormwater Report The Reserve at Palisades 2220348.10 Appendix A Exhibits A-1 .................... Vicinity Map A-2 .................... Existing Conditions A-3 .................... Developed Conditions A-4 .................... NRCS Soil Map A-5 .................... FEMA 100-Year Flood Plain Map 1200 6th Avenue, Suite 1620, Seattle, WA 98101 206.267.2425 TEL 206.267.2429 FAX RESERVE AT PALISADES VICINITY MAP A-1 VICINITY MAP NOT TO SCALE SITE 507 RIDGELINE MIDDLE SCHOOL 507 P A L I S A D E S S T S E CAR T E R L O O P S E LOOP 10 7 T H SE MI L L R D S E MI L L R D S E 107TH LOOP SE MILL POND ELEMENTARY 104TH AVE SE BRIGHTON ST S E S E 10 5 T H A V E P A L I S A D E S W E S T Δ APN 21725130200 S R 5 0 7 PALISA D E S S T S E EXISTING INFILTRATION POND EXISTING WET POND N GRAPHIC SCALE 0 50 100 1" = 50 FEET 25 1 2 3 4 TEL www.ahbl.comWEBTELwww.ahbl.comWEBTELwww.ahbl.comWEB 2215 North 30th Street, Suite 300 Tacoma, WA 98403 253.383.2422TEL www.ahbl.comWEB TACOMA SEATTLE SPOKANE TRI-CITIES Know what's below. before you dig.Call R 253.383.2572 FAX 34 MW/SKMH/ABMH 3/17/2025 PERMIT SET 2220348.10 4802 TACOMA MALL BOULEVARD TACOMA, WA 98409 CONTACT: MATT LEWIS (888) 627-0013 GARRETTE CUSTOM HOMES, INC THE RESERVE AT PALISADES A PORTION OF SECTION 25, TWN. 17N, RGE 01E, W.M, CITY OF YELM, THURSTON COUNTY, WASHINGTON. THE RESERVE AT PALISADES APPLICATION # 2025.00xx DATE: February 11, 2025 FILENAME: Q:\2022\2220348\10_CIV\CAD\_Site Development\2220348-SH-SURV.dwg A-2 EXISTING CONDITIONSLEGAL DESCRIPTION THE WEST 402.4 FEET OF THAT PART OF THE SOUTHWEST QUARTER OF THE NORTHEAST QUARTER OF SECTION 25, TOWNSHIP 17 NORTH, RANGE 1 EAST, W.M. LYING SOUTHEASTERLY OF SECONDARY HIGHWAY NO. 5-H; EXCEPTING THEREFROM THE SOUTH 16.5 FEET; ALSO EXCEPTING THEREFROM THAT PORTION CONVEYED TO THE CITY OF YELM BY DEED RECORDED FEBRUARY 12, 2008 UNDER RECORDING NO. 3988601; IN THURSTON COUNTY, WASHINGTON. 420 414 416 418 420 422 39 0 40 0 41 0 3 8 4 3 8 6 38 8 39 2 39 4 39 6 39 8 40 2 40 4 40 6 40 8 41 2 41 4 41 6 40 6 40 0 39 8 396 398 39 8 420 41 6 41 8 42 2 3 7 0 3 8 0 364 3 7 2 3 7 4 3 7 6 3 7 8 3 8 2 382 3 8 2 3 7 0 3 7 0 38 0 380 39 0 38 2 382 38 4 38 6 38 8 392 36 0 3 7 0 35 6 35 6 35 8 36 2 36 4 3 6 6 3 6 8 410 408 402 CB 18 CB 17 CB 16 CB 15 CB 20 CB 19 CB 12 CB 13 CB 10 CB 9 CB 7 CB 5 CB 6 CB 4 CB 1 CB 2 WQ #1 STORMFILTER VAULT CB 14 CB 11 CB 8 PALI S A D E S S T S E ROAD A S R 5 0 7 CONNECT PROPOSED STORM NETWORK TO EXISTING CATCH BASIN REPLACE EXISTING PIPE OUTLET WITH 24" PIPE AND WATER QUALITY STRUCTURE 2215 North 30th Street, Suite 300, Tacoma, WA 98403 253.383.2422 TEL 253.383.2572 FAX JOB NO. DATE: RESERVE AT PALISADES DEVELOPED CONDITIONS A-3 2220348.10 3/17/2025 N GRAPHIC SCALE 0 40 80 1" = 40 FEET 20 INFILTRATION POND BOTTOM DIM. 170 FT x 50 FT DEPTH 5FT Soil Map—Thurston County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 7/31/2024 Page 1 of 3 51 9 7 5 2 0 51 9 7 5 7 0 51 9 7 6 2 0 51 9 7 6 7 0 51 9 7 7 2 0 51 9 7 7 7 0 51 9 7 8 2 0 51 9 7 8 7 0 51 9 7 9 2 0 51 9 7 9 7 0 51 9 7 5 2 0 51 9 7 5 7 0 51 9 7 6 2 0 51 9 7 6 7 0 51 9 7 7 2 0 51 9 7 7 7 0 51 9 7 8 2 0 51 9 7 8 7 0 51 9 7 9 2 0 51 9 7 9 7 0 528670 528720 528770 528820 528870 528920 528970 528670 528720 528770 528820 528870 528920 528970 46° 56' 4'' N 12 2 ° 3 7 ' 2 5 ' ' W 46° 56' 4'' N 12 2 ° 3 7 ' 8 ' ' W 46° 55' 49'' N 12 2 ° 3 7 ' 2 5 ' ' W 46° 55' 49'' N 12 2 ° 3 7 ' 8 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 100 200 400 600 Feet 0 30 60 120 180 Meters Map Scale: 1:2,250 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. A-4 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 17, Aug 29, 2023 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. Soil Map—Thurston County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 7/31/2024 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 2 Alderwood gravelly sandy loam, 8 to 15 percent slopes 10.0 94.7% 32 Everett very gravelly sandy loam, 0 to 8 percent slopes 0.6 5.3% Totals for Area of Interest 10.6 100.0% Soil Map—Thurston County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 7/31/2024 Page 3 of 3 National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250 Feet Ü SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOOD HAZARD AREAS Without Base Flood Elevation (BFE) Zone A, V, A99 With BFE or DepthZone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areas of 1% annual chance flood with average depth less than one foot or with drainage areas of less than one square mileZone X Future Conditions 1% Annual Chance Flood HazardZone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to LeveeZone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood HazardZone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 7/31/2024 at 11:57 AM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location. 1:6,000 122°37'36"W 46°56'8"N 122°36'59"W 46°55'43"N Basemap Imagery Source: USGS National Map 2023 A-5 Stormwater Report The Reserve at Palisades 2220348.10 Appendix B Facility Sizing B-1 .................... Basin Map B-2 .................... WWHM Report B-3 .................... Conveyance Calculations 18" CMP EL=355.41 18" CMP EL=360.27 STCB#7100 RIM=359.20 12" PVC NE IE=356.05 STCB#501 RIM=360.24 12" CPP W IE=356.68 12" CPP E IE=356.72 12" CPP S IE=357.15 STCB#500 RIM=360.25 12" CPP W IE=357.71 STCB#514 RIM=365.30 12" CPP N IE=360.30 12" CPP E IE=362.44 12" CPP S IE=360.31 STCB#515 RIM=365.29 12" CPP W IE=362.44 STCB#521 RIM=376.43 12" CPP W IE=373.31 STCB#520 RIM=376.40 12" CPP N IE=373.30 12" CPP E IE=373.30 12" CPP S IE=373.31 STCB#990 RIM=388.28 12" CPP N IE=335.07 12" CPP E IE=335.08 12" CPP S IE=335.13 STCB#1450 RIM=388.13 12" CPP SW IE=385.29 40 0 41 0 39 2 39 4 39 6 39 8 40 2 40 4 40 6 40 8 41 2 41 4 41 6 380 39 0 40 041 0 3 7 6 378 382 384 38 638 8 3 9 2 3 9 4 3 9 6 3 9 8 40 2 40 4 40 6 40 841 241 4 414 416 416 41 8 41 8 420 422 4 2 2 42 0 42 2 420 416 418 42 0 41 6 41 8 42 2 4 1 0 40 4 40 6 40 8 41 2 41 4 41 6 400 39 8 402404 39 0 38 4 38 6 38 8 39 2 39 4 39 6 36 0 3 7 0 37 0 3 7 0 3 5 4 35 6 35 8 36 2 36 4 36 6 36 8 3 7 2 3 5 6 3 5 8 3 8 0 3 7 4 3 7 6 3 7 8 3 8 2 3 8 4 3 8 6 3 8 8 3 9 4 3 9 6 4 0 2 4 1 2 414 4 1 6 360 354 356 358 PALI S A D E S S T S E S R 5 0 7 2215 North 30th Street, Suite 300, Tacoma, WA 98403 253.383.2422 TEL 253.383.2572 FAX JOB NO. DATE: RESERVE AT PALISADES BASIN MAP B-1 2220348.10 3/17/2025 N GRAPHIC SCALE 0 50 100 1" = 50 FEET 25 RESERVE AT PALISADES PALISADES WEST INFILTRATION POND WATER QUALITY FILTER VAULT BASIN AREAS LAWN ROAD ROOF DRIVEWAY SIDEWALK POND TOTAL FLAT MOD STEEP FLAT MOD FLAT MOD RESERVE AT PALISADES 2.49 AC 0.53 AC 0.54 AC 0.77 AC 0.68 AC 2.42 AC (2,700 SF EA) 0.60 AC 0.10 AC 0.08 AC -8.21 AC PALISADES WEST1 1.35 AC 0.58 AC 1.02 AC 0.44 AC -0.28 AC 0.11 AC 0.05 AC 3.83 AC BYPASS WQ STRUCTURE 0.25 AC -0.70 AC 0.11 AC ---0.02 AC -0.38 AC 1.46 ac 1 - AREAS PER PALISADES WEST FINAL STORM DRAINAGE REPORT. EXCLUDES ROOF AREAS DRAINING TO ON-LOT DRYWELLS BYPASS WQ STRUCTURE SWALE INCLUDES 500SF DRIVEWAY PER LOT WWHM4 PROJECT REPORT B-2 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 2 General Model Information WWHM2012 Project Name:Palisades-20iph5ft InfPndwPali-2220348 Site Name:Reserve at Palisades Site Address: City:Yelm Report Date:3/17/2025 Gage:Lake Lawrence Data Start:1955/10/01 Data End:2008/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2024/06/28 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year Low Flow Threshold for POC2:50 Percent of the 2 Year High Flow Threshold for POC2:50 Year Low Flow Threshold for POC3:50 Percent of the 2 Year High Flow Threshold for POC3:50 Year Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 3 Landuse Basin Data Predeveloped Land Use Reserve at Palisades Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Mod 0.77 C, Forest, Flat 0.25 C, Forest, Steep 0.51 Pervious Total 1.53 Impervious Land Use acre POND 0.35 Impervious Total 0.35 Basin Total 1.88 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 1 POC 1 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 4 Palisades West Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 1.35 C, Lawn, Mod 0.58 Pervious Total 1.93 Impervious Land Use acre ROADS FLAT 1.02 ROADS MOD 0.44 DRIVEWAYS FLAT 0.28 SIDEWALKS FLAT 0.11 SIDEWALKS MOD 0.05 Impervious Total 1.9 Basin Total 3.83 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 1 POC 1 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 5 Hill Side Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Steep 0.34 C, Forest, Mod 1.51 C, Forest, Flat 1.52 Pervious Total 3.37 Impervious Land Use acre Impervious Total 0 Basin Total 3.37 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 3 POC 3 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 6 Mitigated Land Use Reserve at Palisades Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 2.49 C, Lawn, Mod 0.53 C, Lawn, Steep 0.54 Pervious Total 3.56 Impervious Land Use acre ROADS FLAT 0.77 ROADS MOD 0.68 ROOF TOPS FLAT 2.42 DRIVEWAYS FLAT 0.6 SIDEWALKS FLAT 0.1 SIDEWALKS MOD 0.08 Impervious Total 4.65 Basin Total 8.21 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Trapezoidal Pond Trapezoidal Pond POC 1POC 1 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 7 Palisades West Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 1.35 C, Lawn, Mod 0.58 Pervious Total 1.93 Impervious Land Use acre ROADS FLAT 1.02 ROADS MOD 0.44 DRIVEWAYS FLAT 0.28 SIDEWALKS FLAT 0.11 SIDEWALKS MOD 0.05 Impervious Total 1.9 Basin Total 3.83 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Trapezoidal Pond Trapezoidal Pond POC 1POC 1 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 8 Bypass WQ Structure Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.25 C, Lawn, Steep 0.4 Pervious Total 0.65 Impervious Land Use acre ROADS FLAT 0.11 SIDEWALKS FLAT 0.02 POND 0.38 Impervious Total 0.51 Basin Total 1.16 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Trapezoidal Pond Trapezoidal Pond Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 9 Hill Side Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Steep 0.3 Pervious Total 0.3 Impervious Land Use acre Impervious Total 0 Basin Total 0.3 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Trapezoidal Pond Trapezoidal Pond POC 3POC 3 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 10 Routing Elements Predeveloped Routing Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 11 Mitigated Routing Trapezoidal Pond Bottom Length:170.00 ft. Bottom Width:50.00 ft. Depth:5 ft. Volume at riser head:1.0590 acre-feet. Infiltration On Infiltration rate:20 Infiltration safety factor:1 Total Volume Infiltrated (ac-ft.):2313.449 Total Volume Through Riser (ac-ft.):0.105 Total Volume Through Facility (ac-ft.):2313.554 Percent Infiltrated:100 Total Precip Applied to Facility:0 Total Evap From Facility:0 Side slope 1:3 To 1 Side slope 2:3 To 1 Side slope 3:3 To 1 Side slope 4:3 To 1 Discharge Structure Riser Height:4 ft. Riser Diameter:12 in. Element Outlets: Outlet 1 Outlet 2 Outlet Flows To: Pond Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.195 0.000 0.000 0.000 0.0556 0.196 0.010 0.000 3.935 0.1111 0.198 0.021 0.000 3.935 0.1667 0.200 0.032 0.000 3.935 0.2222 0.201 0.044 0.000 3.935 0.2778 0.203 0.055 0.000 3.935 0.3333 0.205 0.066 0.000 3.935 0.3889 0.207 0.078 0.000 3.935 0.4444 0.208 0.089 0.000 3.935 0.5000 0.210 0.101 0.000 3.935 0.5556 0.212 0.113 0.000 3.935 0.6111 0.214 0.125 0.000 3.935 0.6667 0.215 0.136 0.000 3.935 0.7222 0.217 0.148 0.000 3.935 0.7778 0.219 0.161 0.000 3.935 0.8333 0.221 0.173 0.000 3.935 0.8889 0.222 0.185 0.000 3.935 0.9444 0.224 0.198 0.000 3.935 1.0000 0.226 0.210 0.000 3.935 1.0556 0.228 0.223 0.000 3.935 1.1111 0.229 0.235 0.000 3.935 1.1667 0.231 0.248 0.000 3.935 1.2222 0.233 0.261 0.000 3.935 1.2778 0.235 0.274 0.000 3.935 1.3333 0.237 0.287 0.000 3.935 1.3889 0.238 0.301 0.000 3.935 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 12 1.4444 0.240 0.314 0.000 3.935 1.5000 0.242 0.327 0.000 3.935 1.5556 0.244 0.341 0.000 3.935 1.6111 0.246 0.354 0.000 3.935 1.6667 0.247 0.368 0.000 3.935 1.7222 0.249 0.382 0.000 3.935 1.7778 0.251 0.396 0.000 3.935 1.8333 0.253 0.410 0.000 3.935 1.8889 0.255 0.424 0.000 3.935 1.9444 0.257 0.438 0.000 3.935 2.0000 0.259 0.453 0.000 3.935 2.0556 0.260 0.467 0.000 3.935 2.1111 0.262 0.482 0.000 3.935 2.1667 0.264 0.496 0.000 3.935 2.2222 0.266 0.511 0.000 3.935 2.2778 0.268 0.526 0.000 3.935 2.3333 0.270 0.541 0.000 3.935 2.3889 0.272 0.556 0.000 3.935 2.4444 0.274 0.571 0.000 3.935 2.5000 0.276 0.586 0.000 3.935 2.5556 0.278 0.602 0.000 3.935 2.6111 0.279 0.617 0.000 3.935 2.6667 0.281 0.633 0.000 3.935 2.7222 0.283 0.649 0.000 3.935 2.7778 0.285 0.664 0.000 3.935 2.8333 0.287 0.680 0.000 3.935 2.8889 0.289 0.696 0.000 3.935 2.9444 0.291 0.713 0.000 3.935 3.0000 0.293 0.729 0.000 3.935 3.0556 0.295 0.745 0.000 3.935 3.1111 0.297 0.762 0.000 3.935 3.1667 0.299 0.778 0.000 3.935 3.2222 0.301 0.795 0.000 3.935 3.2778 0.303 0.812 0.000 3.935 3.3333 0.305 0.829 0.000 3.935 3.3889 0.307 0.846 0.000 3.935 3.4444 0.309 0.863 0.000 3.935 3.5000 0.311 0.880 0.000 3.935 3.5556 0.313 0.897 0.000 3.935 3.6111 0.315 0.915 0.000 3.935 3.6667 0.317 0.932 0.000 3.935 3.7222 0.319 0.950 0.000 3.935 3.7778 0.321 0.968 0.000 3.935 3.8333 0.323 0.986 0.000 3.935 3.8889 0.325 1.004 0.000 3.935 3.9444 0.327 1.022 0.000 3.935 4.0000 0.329 1.040 0.000 3.935 4.0556 0.331 1.059 0.138 3.935 4.1111 0.333 1.077 0.389 3.935 4.1667 0.335 1.096 0.703 3.935 4.2222 0.337 1.114 1.046 3.935 4.2778 0.339 1.133 1.383 3.935 4.3333 0.342 1.152 1.683 3.935 4.3889 0.344 1.171 1.921 3.935 4.4444 0.346 1.190 2.088 3.935 4.5000 0.348 1.210 2.203 3.935 4.5556 0.350 1.229 2.347 3.935 4.6111 0.352 1.248 2.462 3.935 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 13 4.6667 0.354 1.268 2.571 3.935 4.7222 0.356 1.288 2.676 3.935 4.7778 0.358 1.308 2.777 3.935 4.8333 0.360 1.328 2.875 3.935 4.8889 0.363 1.348 2.969 3.935 4.9444 0.365 1.368 3.060 3.935 5.0000 0.367 1.388 3.149 3.935 5.0556 0.369 1.409 3.235 3.935 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:39:31 AM Page 14 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:3.46 Total Impervious Area:2.25 Mitigated Landuse Totals for POC #1 Total Pervious Area:5.49 Total Impervious Area:6.55 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 1.651253 5 year 2.471942 10 year 3.120641 25 year 4.070699 50 year 4.880088 100 year 5.78264 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 4.522239 5 year 6.590555 10 year 8.158598 25 year 10.376375 50 year 12.207323 100 year 14.197612 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1956 1.357 3.613 1957 2.940 7.359 1958 1.711 4.688 1959 1.568 4.288 1960 2.547 6.812 1961 1.242 3.375 1962 0.983 2.852 1963 2.486 6.658 1964 1.349 3.907 1965 1.759 4.749 Conveyance sizing flow Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:02 AM Page 15 1966 1.292 3.553 1967 1.516 4.148 1968 0.910 2.550 1969 0.966 2.687 1970 1.087 2.947 1971 1.211 3.226 1972 1.643 4.331 1973 1.203 3.238 1974 3.700 9.184 1975 1.783 4.860 1976 1.443 3.915 1977 2.016 5.660 1978 1.510 4.178 1979 2.152 6.073 1980 1.146 3.123 1981 2.392 6.359 1982 1.526 4.374 1983 2.442 7.154 1984 1.575 4.330 1985 1.426 3.964 1986 1.908 5.006 1987 1.580 4.183 1988 0.769 2.100 1989 0.929 2.560 1990 5.306 13.262 1991 2.469 6.412 1992 1.693 4.572 1993 0.830 2.308 1994 1.496 4.043 1995 2.175 5.997 1996 2.076 5.577 1997 1.510 4.162 1998 2.914 7.817 1999 1.354 3.707 2000 1.337 3.879 2001 1.243 3.596 2002 1.717 4.697 2003 0.979 2.787 2004 4.837 12.112 2005 6.095 15.041 2006 2.714 7.088 2007 2.039 5.481 2008 2.805 7.344 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 6.0945 15.0405 2 5.3057 13.2624 3 4.8374 12.1120 4 3.6995 9.1842 5 2.9398 7.8165 6 2.9137 7.3590 7 2.8055 7.3437 8 2.7135 7.1538 9 2.5473 7.0878 10 2.4864 6.8118 11 2.4686 6.6576 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:02 AM Page 16 12 2.4418 6.4118 13 2.3919 6.3593 14 2.1748 6.0734 15 2.1520 5.9971 16 2.0764 5.6596 17 2.0394 5.5766 18 2.0165 5.4805 19 1.9076 5.0059 20 1.7833 4.8598 21 1.7587 4.7485 22 1.7166 4.6965 23 1.7113 4.6882 24 1.6926 4.5720 25 1.6430 4.3739 26 1.5802 4.3306 27 1.5746 4.3305 28 1.5679 4.2879 29 1.5261 4.1829 30 1.5156 4.1780 31 1.5101 4.1618 32 1.5097 4.1477 33 1.4962 4.0429 34 1.4431 3.9635 35 1.4259 3.9148 36 1.3570 3.9073 37 1.3535 3.8787 38 1.3486 3.7067 39 1.3372 3.6125 40 1.2924 3.5961 41 1.2434 3.5535 42 1.2425 3.3753 43 1.2107 3.2381 44 1.2031 3.2258 45 1.1463 3.1226 46 1.0874 2.9474 47 0.9830 2.8521 48 0.9794 2.7872 49 0.9656 2.6868 50 0.9290 2.5599 51 0.9096 2.5503 52 0.8299 2.3080 53 0.7688 2.0997 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:02 AM Page 17 Duration Flows The Duration Matching Failed Flow(cfs)Predev Mit Percentage Pass/Fail 0.8256 1071 17308 1616 Fail 0.8666 909 15568 1712 Fail 0.9075 805 14033 1743 Fail 0.9485 686 12704 1851 Fail 0.9894 595 11493 1931 Fail 1.0304 518 10417 2011 Fail 1.0714 456 9422 2066 Fail 1.1123 417 8603 2063 Fail 1.1533 370 7856 2123 Fail 1.1942 330 7146 2165 Fail 1.2352 295 6559 2223 Fail 1.2761 258 5982 2318 Fail 1.3171 224 5447 2431 Fail 1.3580 203 4960 2443 Fail 1.3990 175 4535 2591 Fail 1.4399 152 4159 2736 Fail 1.4809 141 3840 2723 Fail 1.5218 127 3546 2792 Fail 1.5628 118 3263 2765 Fail 1.6038 104 3011 2895 Fail 1.6447 91 2793 3069 Fail 1.6857 87 2581 2966 Fail 1.7266 77 2373 3081 Fail 1.7676 72 2223 3087 Fail 1.8085 67 2068 3086 Fail 1.8495 60 1922 3203 Fail 1.8904 55 1799 3270 Fail 1.9314 51 1681 3296 Fail 1.9723 49 1568 3200 Fail 2.0133 48 1456 3033 Fail 2.0543 42 1380 3285 Fail 2.0952 39 1298 3328 Fail 2.1362 34 1218 3582 Fail 2.1771 30 1146 3820 Fail 2.2181 28 1077 3846 Fail 2.2590 27 1015 3759 Fail 2.3000 25 967 3868 Fail 2.3409 23 921 4004 Fail 2.3819 22 880 4000 Fail 2.4228 19 843 4436 Fail 2.4638 17 791 4652 Fail 2.5047 15 757 5046 Fail 2.5457 14 717 5121 Fail 2.5867 12 676 5633 Fail 2.6276 12 650 5416 Fail 2.6686 12 607 5058 Fail 2.7095 11 576 5236 Fail 2.7505 8 555 6937 Fail 2.7914 8 535 6687 Fail 2.8324 7 501 7157 Fail 2.8733 7 473 6757 Fail 2.9143 6 445 7416 Fail 2.9552 5 427 8540 Fail 2.9962 5 408 8160 Fail Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:02 AM Page 18 3.0372 5 395 7900 Fail 3.0781 5 388 7760 Fail 3.1191 4 372 9300 Fail 3.1600 4 348 8700 Fail 3.2010 4 334 8350 Fail 3.2419 4 317 7925 Fail 3.2829 4 306 7650 Fail 3.3238 4 292 7300 Fail 3.3648 4 277 6925 Fail 3.4057 4 259 6475 Fail 3.4467 4 253 6325 Fail 3.4876 4 245 6125 Fail 3.5286 4 236 5900 Fail 3.5696 4 227 5675 Fail 3.6105 4 213 5325 Fail 3.6515 4 204 5100 Fail 3.6924 4 197 4925 Fail 3.7334 3 188 6266 Fail 3.7743 3 179 5966 Fail 3.8153 3 169 5633 Fail 3.8562 3 164 5466 Fail 3.8972 3 159 5300 Fail 3.9381 3 153 5100 Fail 3.9791 3 145 4833 Fail 4.0201 3 141 4700 Fail 4.0610 3 136 4533 Fail 4.1020 3 130 4333 Fail 4.1429 3 126 4200 Fail 4.1839 3 114 3800 Fail 4.2248 3 109 3633 Fail 4.2658 3 107 3566 Fail 4.3067 3 104 3466 Fail 4.3477 3 98 3266 Fail 4.3886 3 96 3200 Fail 4.4296 3 93 3100 Fail 4.4705 3 89 2966 Fail 4.5115 3 87 2900 Fail 4.5525 3 82 2733 Fail 4.5934 3 78 2600 Fail 4.6344 3 77 2566 Fail 4.6753 3 77 2566 Fail 4.7163 3 71 2366 Fail 4.7572 3 70 2333 Fail 4.7982 3 68 2266 Fail 4.8391 2 65 3250 Fail 4.8801 2 61 3050 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. Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:02 AM Page 19 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:1.4537 acre-feet On-line facility target flow:1.4075 cfs. Adjusted for 15 min:1.4075 cfs. Off-line facility target flow:0.7792 cfs. Adjusted for 15 min:0.7792 cfs. WQ Treatment flow rate Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:02 AM Page 20 POC 2 POC #2 was not reported because POC must exist in both scenarios and both scenarios must have been run. Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:02 AM Page 21 POC 3 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #3 Total Pervious Area:3.37 Total Impervious Area:0 Mitigated Landuse Totals for POC #3 Total Pervious Area:0.3 Total Impervious Area:0 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #3 Return Period Flow(cfs) 2 year 0.222575 5 year 0.419889 10 year 0.610027 25 year 0.938736 50 year 1.263112 100 year 1.670402 Flow Frequency Return Periods for Mitigated. POC #3 Return Period Flow(cfs) 2 year 0.080503 5 year 0.140902 10 year 0.189978 25 year 0.26252 50 year 0.324363 100 year 0.393036 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #3 Year Predeveloped Mitigated 1956 0.220 0.066 1957 0.770 0.172 1958 0.180 0.089 1959 0.186 0.075 1960 0.372 0.144 1961 0.177 0.065 1962 0.068 0.021 1963 0.356 0.143 1964 0.182 0.042 1965 0.222 0.092 1966 0.124 0.058 Swale design flow Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:25 AM Page 22 1967 0.202 0.094 1968 0.147 0.035 1969 0.097 0.035 1970 0.167 0.045 1971 0.206 0.057 1972 0.328 0.091 1973 0.178 0.051 1974 0.977 0.250 1975 0.201 0.094 1976 0.233 0.072 1977 0.117 0.103 1978 0.226 0.075 1979 0.163 0.117 1980 0.180 0.054 1981 0.366 0.142 1982 0.153 0.067 1983 0.285 0.118 1984 0.191 0.079 1985 0.111 0.063 1986 0.370 0.108 1987 0.270 0.081 1988 0.135 0.025 1989 0.141 0.035 1990 1.397 0.321 1991 0.501 0.147 1992 0.222 0.088 1993 0.085 0.028 1994 0.193 0.073 1995 0.244 0.106 1996 0.310 0.110 1997 0.259 0.080 1998 0.436 0.173 1999 0.155 0.057 2000 0.145 0.026 2001 0.066 0.035 2002 0.270 0.092 2003 0.117 0.034 2004 1.273 0.297 2005 1.752 0.381 2006 0.495 0.158 2007 0.287 0.112 2008 0.554 0.169 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #3 Rank Predeveloped Mitigated 1 1.7522 0.3806 2 1.3971 0.3214 3 1.2729 0.2974 4 0.9774 0.2499 5 0.7699 0.1728 6 0.5540 0.1719 7 0.5005 0.1692 8 0.4953 0.1583 9 0.4355 0.1470 10 0.3717 0.1445 11 0.3696 0.1426 12 0.3658 0.1417 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:25 AM Page 23 13 0.3559 0.1182 14 0.3281 0.1168 15 0.3102 0.1124 16 0.2867 0.1098 17 0.2852 0.1075 18 0.2702 0.1064 19 0.2701 0.1028 20 0.2590 0.0943 21 0.2438 0.0941 22 0.2328 0.0924 23 0.2263 0.0918 24 0.2219 0.0908 25 0.2217 0.0891 26 0.2199 0.0878 27 0.2063 0.0813 28 0.2016 0.0801 29 0.2009 0.0788 30 0.1927 0.0753 31 0.1908 0.0745 32 0.1858 0.0734 33 0.1819 0.0722 34 0.1804 0.0675 35 0.1800 0.0657 36 0.1777 0.0653 37 0.1773 0.0632 38 0.1668 0.0582 39 0.1626 0.0572 40 0.1547 0.0569 41 0.1528 0.0537 42 0.1466 0.0512 43 0.1450 0.0452 44 0.1412 0.0417 45 0.1354 0.0355 46 0.1245 0.0353 47 0.1173 0.0349 48 0.1168 0.0346 49 0.1114 0.0339 50 0.0970 0.0285 51 0.0851 0.0259 52 0.0683 0.0252 53 0.0663 0.0209 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:25 AM Page 24 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.1113 11461 42 0 Pass 0.1229 8850 29 0 Pass 0.1346 6809 21 0 Pass 0.1462 5165 14 0 Pass 0.1578 4055 10 0 Pass 0.1695 3198 7 0 Pass 0.1811 2515 4 0 Pass 0.1927 2039 4 0 Pass 0.2044 1629 4 0 Pass 0.2160 1345 4 0 Pass 0.2276 1067 4 0 Pass 0.2393 841 4 0 Pass 0.2509 665 3 0 Pass 0.2625 515 3 0 Pass 0.2742 367 3 0 Pass 0.2858 308 3 0 Pass 0.2974 258 3 1 Pass 0.3091 209 2 0 Pass 0.3207 187 2 1 Pass 0.3323 171 1 0 Pass 0.3440 161 1 0 Pass 0.3556 144 1 0 Pass 0.3672 127 1 0 Pass 0.3789 113 1 0 Pass 0.3905 100 0 0 Pass 0.4022 85 0 0 Pass 0.4138 78 0 0 Pass 0.4254 73 0 0 Pass 0.4371 66 0 0 Pass 0.4487 57 0 0 Pass 0.4603 53 0 0 Pass 0.4720 44 0 0 Pass 0.4836 38 0 0 Pass 0.4952 30 0 0 Pass 0.5069 20 0 0 Pass 0.5185 16 0 0 Pass 0.5301 10 0 0 Pass 0.5418 10 0 0 Pass 0.5534 8 0 0 Pass 0.5650 7 0 0 Pass 0.5767 7 0 0 Pass 0.5883 7 0 0 Pass 0.5999 7 0 0 Pass 0.6116 7 0 0 Pass 0.6232 6 0 0 Pass 0.6348 6 0 0 Pass 0.6465 6 0 0 Pass 0.6581 6 0 0 Pass 0.6697 6 0 0 Pass 0.6814 6 0 0 Pass 0.6930 6 0 0 Pass 0.7047 6 0 0 Pass 0.7163 6 0 0 Pass Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:25 AM Page 25 0.7279 5 0 0 Pass 0.7396 5 0 0 Pass 0.7512 5 0 0 Pass 0.7628 5 0 0 Pass 0.7745 4 0 0 Pass 0.7861 4 0 0 Pass 0.7977 4 0 0 Pass 0.8094 4 0 0 Pass 0.8210 4 0 0 Pass 0.8326 4 0 0 Pass 0.8443 4 0 0 Pass 0.8559 4 0 0 Pass 0.8675 4 0 0 Pass 0.8792 4 0 0 Pass 0.8908 4 0 0 Pass 0.9024 4 0 0 Pass 0.9141 4 0 0 Pass 0.9257 4 0 0 Pass 0.9373 4 0 0 Pass 0.9490 4 0 0 Pass 0.9606 4 0 0 Pass 0.9722 4 0 0 Pass 0.9839 3 0 0 Pass 0.9955 3 0 0 Pass 1.0072 3 0 0 Pass 1.0188 3 0 0 Pass 1.0304 3 0 0 Pass 1.0421 3 0 0 Pass 1.0537 3 0 0 Pass 1.0653 3 0 0 Pass 1.0770 3 0 0 Pass 1.0886 3 0 0 Pass 1.1002 3 0 0 Pass 1.1119 3 0 0 Pass 1.1235 3 0 0 Pass 1.1351 3 0 0 Pass 1.1468 3 0 0 Pass 1.1584 3 0 0 Pass 1.1700 3 0 0 Pass 1.1817 3 0 0 Pass 1.1933 3 0 0 Pass 1.2049 3 0 0 Pass 1.2166 3 0 0 Pass 1.2282 3 0 0 Pass 1.2398 3 0 0 Pass 1.2515 3 0 0 Pass 1.2631 3 0 0 Pass Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:25 AM Page 26 Water Quality Water Quality BMP Flow and Volume for POC #3 On-line facility volume:0 acre-feet On-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Off-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:25 AM Page 27 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. Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:25 AM Page 28 Appendix Predeveloped Schematic Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:26 AM Page 29 Mitigated Schematic Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:28 AM Page 30 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1955 10 01 END 2008 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 Palisades-20iph5ft InfPndwPali-2220348.wdm MESSU 25 PrePalisades-20iph5ft InfPndwPali-2220348.MES 27 PrePalisades-20iph5ft InfPndwPali-2220348.L61 28 PrePalisades-20iph5ft InfPndwPali-2220348.L62 30 POCPalisades-20iph5ft InfPndwPali-22203481.dat 32 POCPalisades-20iph5ft InfPndwPali-22203483.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 11 PERLND 10 PERLND 12 IMPLND 14 PERLND 16 PERLND 17 IMPLND 1 IMPLND 2 IMPLND 5 IMPLND 8 IMPLND 9 COPY 501 COPY 503 DISPLY 1 DISPLY 3 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Reserve at Palisades MAX 1 2 30 9 3 Hill Side MAX 1 2 32 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 503 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 11 C, Forest, Mod 1 1 1 1 27 0 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:28 AM Page 31 10 C, Forest, Flat 1 1 1 1 27 0 12 C, Forest, Steep 1 1 1 1 27 0 16 C, Lawn, Flat 1 1 1 1 27 0 17 C, Lawn, Mod 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 11 0 0 1 0 0 0 0 0 0 0 0 0 10 0 0 1 0 0 0 0 0 0 0 0 0 12 0 0 1 0 0 0 0 0 0 0 0 0 16 0 0 1 0 0 0 0 0 0 0 0 0 17 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 ********* 11 0 0 4 0 0 0 0 0 0 0 0 0 1 9 10 0 0 4 0 0 0 0 0 0 0 0 0 1 9 12 0 0 4 0 0 0 0 0 0 0 0 0 1 9 16 0 0 4 0 0 0 0 0 0 0 0 0 1 9 17 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 *** 11 0 0 0 0 0 0 0 0 0 0 0 10 0 0 0 0 0 0 0 0 0 0 0 12 0 0 0 0 0 0 0 0 0 0 0 16 0 0 0 0 0 0 0 0 0 0 0 17 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 11 0 4.5 0.08 400 0.1 0.5 0.996 10 0 4.5 0.08 400 0.05 0.5 0.996 12 0 4.5 0.08 400 0.15 0.5 0.996 16 0 4.5 0.03 400 0.05 0.5 0.996 17 0 4.5 0.03 400 0.1 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 11 0 0 2 2 0 0 0 10 0 0 2 2 0 0 0 12 0 0 2 2 0 0 0 16 0 0 2 2 0 0 0 17 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 11 0.2 0.5 0.35 6 0.5 0.7 10 0.2 0.5 0.35 6 0.5 0.7 12 0.2 0.3 0.35 6 0.3 0.7 16 0.1 0.25 0.25 6 0.5 0.25 17 0.1 0.25 0.25 6 0.5 0.25 END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:28 AM Page 32 11 0 0 0 0 2.5 1 0 10 0 0 0 0 2.5 1 0 12 0 0 0 0 2.5 1 0 16 0 0 0 0 2.5 1 0 17 0 0 0 0 2.5 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 14 POND 1 1 1 27 0 1 ROADS/FLAT 1 1 1 27 0 2 ROADS/MOD 1 1 1 27 0 5 DRIVEWAYS/FLAT 1 1 1 27 0 8 SIDEWALKS/FLAT 1 1 1 27 0 9 SIDEWALKS/MOD 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 14 0 0 1 0 0 0 1 0 0 1 0 0 0 2 0 0 1 0 0 0 5 0 0 1 0 0 0 8 0 0 1 0 0 0 9 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 14 0 0 4 0 0 0 1 9 1 0 0 4 0 0 0 1 9 2 0 0 4 0 0 0 1 9 5 0 0 4 0 0 0 1 9 8 0 0 4 0 0 0 1 9 9 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 14 0 0 0 0 0 1 0 0 0 0 0 2 0 0 0 0 0 5 0 0 0 0 0 8 0 0 0 0 0 9 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 14 400 0.01 0.1 0.1 1 400 0.01 0.1 0.1 2 400 0.05 0.1 0.08 5 400 0.01 0.1 0.1 8 400 0.01 0.1 0.1 9 400 0.05 0.1 0.08 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:28 AM Page 33 14 0 0 1 0 0 2 0 0 5 0 0 8 0 0 9 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 14 0 0 1 0 0 2 0 0 5 0 0 8 0 0 9 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Reserve at Palisades*** PERLND 11 0.77 COPY 501 12 PERLND 11 0.77 COPY 501 13 PERLND 10 0.25 COPY 501 12 PERLND 10 0.25 COPY 501 13 PERLND 12 0.51 COPY 501 12 PERLND 12 0.51 COPY 501 13 IMPLND 14 0.35 COPY 501 15 Palisades West*** PERLND 16 1.35 COPY 501 12 PERLND 16 1.35 COPY 501 13 PERLND 17 0.58 COPY 501 12 PERLND 17 0.58 COPY 501 13 IMPLND 1 1.02 COPY 501 15 IMPLND 2 0.44 COPY 501 15 IMPLND 5 0.28 COPY 501 15 IMPLND 8 0.11 COPY 501 15 IMPLND 9 0.05 COPY 501 15 Hill Side*** PERLND 12 0.34 COPY 503 12 PERLND 12 0.34 COPY 503 13 PERLND 11 1.51 COPY 503 12 PERLND 11 1.51 COPY 503 13 PERLND 10 1.52 COPY 503 12 PERLND 10 1.52 COPY 503 13 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 COPY 503 OUTPUT MEAN 1 1 48.4 DISPLY 3 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:28 AM Page 34 END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL COPY 503 OUTPUT MEAN 1 1 48.4 WDM 503 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:28 AM Page 35 END MASS-LINK END RUN Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:28 AM Page 36 Mitigated UCI File Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:28 AM Page 37 Predeveloped HSPF Message File Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:28 AM Page 38 Mitigated HSPF Message File Palisades-20iph5ft InfPndwPali-2220348 3/17/2025 8:40:28 AM Page 39 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2025; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com Inputs: Pipe Diameter, dₒ2.000 ft Manning Roughness, n ?0.018 Pipe Slope, sₒ0.010 rise/run Percent of (or ratio to) full depth (100% or 1 if flowing full)1.000 fraction Results: Maximum Flow Through Pipe, Q 16.382 ft^3/s Velocity, v 5.215 ft/s Velocity head, hv 0.423 ft Flow Area, A 3.142 ft^2/s Wetted Perimeter, P 6.283 ft Hydraulic Radius 0.500 ft Required 25 Year Flow to Pipe (Per WWHM)10.3764 ft^3/s Meets Capacity Requirement Developed Site Flows 25-Year Flow 10.3764 Equations: Most Constricting Pipe Capacity Calculation = = ⁄ ⁄ B-3.1 Manning's Roughness Coefficient - n - Asbestos cement 0.011 Asphalt 0.016 Brass 0.011 Brick 0.015 Canvas 0.012 Cast-iron, new 0.012 Clay tile 0.014 Concrete - steel forms 0.011 Concrete (Cement) - finished 0.012 Concrete - wooden forms 0.015 Earth, smooth 0.018 Earth channel - clean 0.022 Earth channel - gravelly 0.025 Earth channel - weedy 0.03 Earth channel - stony, cobbles 0.035 Floodplains - pasture, farmland 0.035 Floodplains - light brush 0.05 Floodplains - heavy brush 0.075 Floodplains - trees 0.15 Galvanized iron 0.016 Glass 0.01 Gravel, firm 0.023 Lead 0.011 Masonry 0.025 Natural streams - sluggish with deep pools 0.04 Natural channels, very poor condition 0.06 Plastic 0.009 Polyethylene PE - Corrugated with smooth inner walls 0.009 - 0.015 Polyethylene PE - Corrugated with corrugated inner walls 0.018 - 0.025 Polyvinyl Chloride PVC - with smooth inner walls 0.009 - 0.011 Rubble Masonry 0.017 Steel - Coal-tar enamel 0.01 Surface Material Steel - smooth 0.012 Steel - New unlined 0.011 Steel - Riveted 0.019 Vitrified Sewer 0.013 - 0.015 Wood - planed 0.012 Wood - unplaned 0.013 Wood stove pipe, small diameter 0.011 - 0.012 Wood stove pipe, large diameter 0.012 - 0.013 2215 N. 30th Street, #300 Tacoma, WA 98403 253.383.2422 TEL 253.383.2572 FAX www.ahbl.com The Reserve at Palisades 2220348.10 Swale Sizing Calculations B-3.2 Swale Dimensions 10-yr flow Flow generated by the sites north hill Stormwater Report The Reserve at Palisades 2220348.10 Appendix C Geotechnical Report GeoResources, LLC October 10, 2024 October 10, 2024 Garrette Custom Homes 11815 NE 99th St #1200 Vancouver, Washington 98682 Attn: Kimberly Johnson KimberlyJ@BuildGCH.com Soils Report Proposed Residential Plat xxx – Palisades Street SE Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.SR INTRODUCTION This Soils Report presents the results of our literature review, subsurface explorations, laboratory testing, and provides geotechnical conclusions and recommendations regarding the feasibility of onsite stormwater infiltration for the proposed residential plat to be constructed at the above referenced parcel in the City of Yelm, Washington. The general location of the site is shown on the attached Site Location Map, Figure 1. Our understanding of the project is based on our conversations with you; our review of the Preliminary Site Plan prepared by AHBL on November 14, 2023; our January 9 and February 7, 2024 site visits and subsurface explorations; our understanding of the City of Yelm (the City) development codes; and our experience in the site area. The site is currently undeveloped. You propose to construct a 39-lot residential plat with a paved shared access roadway and associated utilities. We anticipate that the proposed residences will be one- to two-story, wood-framed structures supported by conventional shallow foundations. A copy of the Preliminary Site Plan is included in the attached Site & Exploration Plan, Figure 2. Because of the amount of proposed hard surfacing associated with the development, the City will require a Soils Report be prepared in accordance with the adopted 2024 Stormwater Management Manual for Western Washington (SWMMWW). PURPOSE & SCOPE The purpose of our scope services was to evaluate the surface and subsurface conditions across the site as a basis for providing stormwater infiltration recommendations and design criteria for the proposed residential plat. Specifically, the scope of services for this project included the following: 1. Reviewing the available geologic, hydrogeologic, and geotechnical data for the site area; 2. Exploring surface and subsurface conditions across the site by excavating 19 test pits and 1 hand auger at select locations and installing shallow (less than 10 feet) groundwater monitoring standpipes in 3 of the test pits; GCH.MattocksPlat.SR_Oct2024 October 10, 2024 page | 2 3. While onsite, performing one small-scale Pilot Infiltration Test (PIT) in accordance with the 2024 SWMMWW in a location specified by the civil engineer; 4. Describing surface and subsurface conditions, including soil type, depth to groundwater, and an estimate of seasonal high groundwater levels based on wet season groundwater monitoring; 5. Providing our opinion about the feasibility of onsite infiltration in accordance with the 2024 SWMMWW, including a preliminary design infiltration rate based on infiltration testing, as applicable; and, 6. Preparing this written Soils Report summarizing our site observations and conclusions, and our recommendations and design criteria, along with the supporting data. The above scope of work was summarized in our Proposal for Geotechnical Engineering Services dated December 21, 2023. We received your emailed authorization to proceed on December 26, 2023. SITE CONDITIONS Surface Conditions The site consists of a single unaddressed tax parcel located in the City of Yelm, Washington. The site is generally rectangular in shape, measures about 400 feet wide (east to west) by about 890 to 1,185 feet long (north to south), and encompasses approximately 9.71 acres. The site is bounded by State Route 507 to the north and existing single-family residential development to the east, south, and west. Access to the site is gained from Palisades Street Southeast in the southeast portion of the site. The site is located on the northern margins of the Yelm glacial upland area. Our site description is based on 2-foot elevation contours shown on the Thurston County online Show Me Everything map and our site observations. A storm pond for the residential plat east of the site occupies the northern corner of the site. South of the storm pond and SR 507, the ground surface slopes up to the south at about 18 to 20 percent. The central portion of the site slopes up to the southeast at 5 to 10 percent, and then levels in the southern portion to about 2 percent. Total topographic relief across the site is on the order of 62 feet. Existing site conditions and topography are shown on the attached Site & Exploration Plan, Figure 2 and Site Vicinity Map, Figure 3. Vegetation consists of Douglas fir trees scattered across the site with a dense understory of grasses, Scotch broom, Himalayan blackberries, and other low growing shrubs. No standing water or groundwater springs were observed at the ground surface at the time of our site visit. We did observe some water ponded in the stormwater pond, as it was raining during our January 9, 2024 site visit. We did not observe signs of slope instability or soil erosion at the time of our site visit. Site Soils The USDA Natural Resource Conservation Service (NRCS) Web Soil Survey maps the surficial soils at the site as Alderwood gravelly sandy loam (2) and Everett very gravelly sandy loam (32). Detailed descriptions of these soils are included below, and an excerpt of the referenced NRCS map for the site and adjacent areas is attached as Figure 4. • Alderwood gravelly sandy loam (2): Mapped throughout the majority of the site, these soils are derived from glacial drift and/or glacial outwash over dense glaciomarine deposits and are GCH.MattocksPlat.SR_Oct2024 October 10, 2024 page | 3 included in hydrologic soil group B. Type 2 soils form on slopes of 8 to 15 percent and are listed as a “slight” erosion hazard when exposed. • Everett very gravelly sandy loam (32): Mapped in the northeastern corner of the site, these soils are derived from sandy and gravelly glacial outwash and are included in hydrologic soil group A. Type 32 soils form on slopes of 0 to 8 percent and are listed as a “slight” erosion hazard when exposed. Site Geology Based on our review of the Geologic Map of the Centralia Quadrangle, Washington (Schasse, 1987), the site is located in an area mapped as being underlain by Vashon till (Qdvt) and Vashon outwash gravel (Qdvg). No landslides, colluvial/alluvial fans, or other deposits of mass wastage are mapped on or within the site vicinity. Detailed descriptions of the mapped geologic units are included below, and an excerpt of the referenced geologic map is attached as Figure 5. • Vashon outwash gravel (Qdvg): Recessional outwash was deposited during the end stages of the Vashon Stade of the Fraser Glaciation, approximately 12,000 to 15,000 years ago by meltwater streams flowing from the retreating continental ice mass. Recessional outwash typically consists of well graded, lightly stratified to locally cross-bedded mixtures of sand and gravel. This unit is considered normally consolidated, offers moderate strength characteristics when undisturbed, and is loose near the surface and increases in density with depth. The infiltration potential of recessional outwash is generally favorable. • Vashon glacial till (Qdvt): Glacial till typically consists of a heterogeneous mixture of clay, silt, sand, and gravel deposited at the base of the continental ice mass and is subsequently over-ridden. Accordingly, these deposits are considered to be overconsolidated and typically offer high strength and low compressibility characteristics, where undisturbed. Infiltration potential within glacial till is generally limited due to its overconsolidated and fine-grained nature. Subsurface Explorations On January 9, 2024, we visited the site and monitored the excavation of 12 test pits to depths of about 5.0 to 10.0 feet below the existing ground surface. We also performed a small-scale Pilot Infiltration Test (PIT) in test pit TP-1 at a depth of 4 feet below the ground surface. On February 7, 2024 we returned to the site and monitored the excavation of 7 additional test pits to depths of 9.0 to 12.5 feet below the existing ground surface and advanced one hand auger to a depth of approximately 3.5 feet below the existing ground surface in the existing southern stormwater pond. Our field staff logged the subsurface conditions encountered in each exploration and obtained representative soil samples. The indicated test pit locations were determined by taping or pacing from existing site features and reference points; as such, the locations should only be considered as accurate as implied by the measurement method. Elevations for our test pits and in- situ testing were taken by interpolating between contours from the WA DNR Thurston 2021 DTM 53 LiDAR dataset. The soils encountered were visually classified in accordance with the Unified Soil Classification System (USCS) and ASTM D2488. The USCS is included in Appendix A as Figure A-1, while the descriptive logs of our test pits and hand augers are included as Figures A-2 through A-(. Table 1 below GCH.MattocksPlat.SR_Oct2024 October 10, 2024 page | 4 summarizes the approximate functional locations, surface elevations, and termination depths of the explorations. The specific number, locations, and depths of our explorations were selected based on the configuration of the proposed development and were adjusted in the field based on consideration for underground utilities, existing site conditions, site access limitations and encountered stratigraphy. The subsurface explorations completed as part of this evaluation indicate the subsurface conditions at specific locations only, as actual subsurface conditions can vary across the site. The nature and extent of such variation would not become evident until additional explorations are performed or until construction activities have begun. TABLE 1: APPROXIMATE LOCATIONS, ELEVATIONS, AND DEPTHS OF EXPLORATIONS Test Pit Number Functional Location Surface Elevation1 (feet) Termination Depth (feet) Termination Elevation (feet) TP-1 Storm Tract F 360 10.0 350.0 TP-2 Northeast portion of Access Roadway 384 6.0 378.0 TP-3 Proposed Lot 18 394 8.0 386.0 TP-4 Proposed Lots 25, 26, 30, & 31 409 6.0 403.0 TP-5 Proposed Lot 23 401 6.0 395.0 TP-6 Proposed Lot 38 420 6.0 414.0 TP-7 Proposed Lot 1 360 7.0 353.0 TP-8 Proposed Lot 4 405 7.0 398.0 TP-9 Center south portion of Access Roadway 407 5.0 402.0 TP-10 Proposed Lot 10 404 5.0 399.0 TP-11 Proposed Lot 4 405 6.0 399.0 TP-12 Proposed Lot 14 396 5.0 391.0 TP-101 Storm Tract F 360 12.5 347.5 TP-102 Tract E 368 11.5 356.5 TP-103 Tract E 370 10.5 359.5 TP-104 Proposed Lot 16 376 9.5 366.5 TP-105 Northern proposed road 380 11.5 368.5 TP-106 Proposed Lot 23 396 9.5 386.5 TP-107 Proposed Lot 29 404 9.0 395.0 HA-1 Existing stormwater facility 357 3.5 353.5 Notes: 1 = Surface elevations estimated by interpolating between contours derived from WA DNR Thurston 2020 LiDAR (Datum: NAVD88) Test Pits The test pits were excavated using a small track-mounted excavator operated by a licensed earthwork contractor working for GeoResources. Our field representative logged the subsurface conditions encountered in each test pit and obtained representative soil samples, which were placed in sealed plastic bags and then taken to our laboratory for further examination and testing as deemed GCH.MattocksPlat.SR_Oct2024 October 10, 2024 page | 5 necessary. The soil densities presented on the logs were based on the difficulty of excavation and our experience. The test pits were backfilled with excavated soil and tamped in place, but not otherwise compacted. Open standpipe piezometers (OSPs) were installed in three of the test pits. The piezometers consisted of 2-inch PVC pipe, with a perforated or slotted section within the lower 3 feet. The Piezometer installations were backfilled with the native soils and affixed with a threaded cap for future measurement of groundwater levels. Pilot Infiltration Test (PIT) We performed one small-scale pilot infiltration test (PIT) in accordance with Volume III, Appendix A of the 2021 Pierce County Stormwater Management and Site Development Manual. The PIT was completed adjacent to the existing stormwater pond in the northern portion of the site. However, the PIT was performed at 4.0 feet below the ground surface in what was later determined to be fill material. The soils at the elevation the test was performed at generally consisted of sandy silt with gravel, likely placed as part of the construction of the pond berm and previous site grading. After the PIT was completed, we over excavated the test pit an additional 6.0 feet to a final depth of 10.0 feet below ground surface and collected representative soil samples. Soil encountered approximately 6 feet below the ground surface to the full depth explored consisted of poorly graded gravel with limited amounts of silt. Subsurface Conditions At the locations of our test pits, we encountered subsurface conditions that, in our opinion, generally confirm the mapped stratigraphy at the site. Our test pits encountered soils that appeared to be consistent with topsoil and undocumented fill soils overlying glacial till. These soil layers are described below. • Topsoil: Our test pits encountered about 0.25 to 1.0 feet of dark brown topsoil. • Undocumented fill: Underlying the topsoil in test pits TP-1, TP-7, TP-101, and TP-106 we observed 2.5 to 5.5 feet of brown-grey sandy silt and medium brown gravelly silty sand in a moist condition. • Vashon glacial till: Underlying the topsoil and fill soils in test pits TP-2 through TP-12, TP-104, TP- 106, and TP-107, we observed a medium dense to very dense, grey-brown to grey sandy silty gravel and gravelly silty sand in a moist to wet condition to the full depth of exploration. We interpret these soils to be weathered and undisturbed glacial till. • Weathered Advance Outwash: Underlying the topsoil in test pits TP-102, TP-103, and TP-105, we encountered brown silty sand with some gravel in a medium dense, moist condition. We interpret these soils to be weathered advance outwash. • Advance Outwash: Underlying the weathered advance outwash and the undocumented fill in TP- 1 and TP-101, we encountered grey poorly graded sand with silt and gravel, and grey poorly graded gravel in a dense to very dense, moist condition. We interpret these soils to be advance outwash. The advance outwash was encountered to the full depth explored where encountered. GCH.MattocksPlat.SR_Oct2024 October 10, 2024 page | 6 TABLE 2: APPROXIMATE DEPTHS AND EXLEVATIONS OF ENCOUNTERED SOILS TYPES Exploration Number Thickness of (feet) Depth to Undisturbed Till (feet) Depth to Advance Outwash (feet) Elevation 1 of Advance Outwash (feet) Topsoil Fill Weathered Soils TP-1 0.5 5.5 NE NE 6.0 354.0 TP-2 0.5 NE 2.0 2.5 NE NE TP-3 0.75 NE 2.75 3.5 NE NE TP-4 0.75 NE 3.25 4.0 NE NE TP-5 0.5 NE 3.5 4.0 NE NE TP-6 0.5 NE 2.5 3.0 NE NE TP-7 0.5 2.5 NE 3.0 NE NE TP-8 0.5 NE 4.5 5.0 NE NE TP-9 0.75 NE 2.25 3.0 NE NE TP-10 0.75 NE 1.25 2.0 NE NE TP-11 0.5 NE 3.5 4.0 NE NE TP-12 0.75 NE 2.25 3.0 NE NE TP-101 0.75 4.25 NE NE 5.0 355.0 TP-102 1.0 NE 3.25 NE 4.25 363.75 TP-103 1.0 NE 2.5 NE 3.5 366.5 TP-104 0.75 NE 2.25 3.0 NE NE TP-105 1.0 NE 2.5 NE 3.5 376.5 TP-106 1.0 2.25 1.75 5.0 NE NE TP-107 0.5 NE 1.5 2.0 NE NE HA-1 0.25 NE NE NE 0.25 356.75 Notes: 1 = Surface elevations estimated by interpolating between contours derived from WA DNR Thurston 2020 LiDAR (Datum: NAVD88) Laboratory Testing Geotechnical laboratory tests were performed on select samples retrieved from the test pits to estimate index engineering properties of the soils encountered. Laboratory testing included visual soil classification per ASTM D2488 and ASTM D2487, moisture content determinations per ASTM D2216 and grain size analyses per ASTM D6913 standard procedures. Test results are summarized below in Table 3 and graphical output results are included in Appendix B. GCH.MattocksPlat.SR_Oct2024 October 10, 2024 page | 7 TABLE 3: LABORATORY TEST RESULTS FOR ON -SITE SOILS Sample Soil Type Lab ID Gravel Content (percent) Sand Content (percent) Silt/Clay Content (percent) Moisture Content (percent) TP-1, S-2, D: 4ft ML 104657 20.4 28.2 51.4 22.9 TP-5, S-2, D: 3.5ft GP-GM 104658 56.3 32.8 10.9 10.4 TP-9, S-1, D: 2ft GW-GM 104659 64.0 30.9 5.1 6.4 TP-11, S-1, D: 1ft SM 104660 30.5 49.0 20.5 20.8 TP-8, S-1, D: 2ft SM 104663 39.8 44.5 15.7 15.9 TP-101, S-1, D: 8’ GP 104798 83.4 12.6 4.0 3.4 TP-102, S-2, D; 8.5’ SP-SM 104799 28.4 65.0 6.6 7.3 Groundwater Conditions Groundwater seepage was observed in test pit TP-7 at a depth of 1.5 feet below existing grades at the time of excavation during our first explorations in January 2024. When we returned to the site on February 7, 2024 groundwater seepage was observed in test pit TP-101 at approximately 11 feet below ground surface. Based on the elevations of the encountered groundwater seepage, we anticipate this is an inconsistent seasonal perched groundwater table. The groundwater encountered in test pit TP-101 is likely an unconfined regional groundwater table. As such, we estimate that seasonal high groundwater within the advance outwash is near elevation 349 feet. We anticipate fluctuations in the local groundwater levels will occur in response to precipitation patterns, off-site construction activities, and site utilization. As such, water level observations made at the time of our field investigation may vary from those encountered during the construction phase. We performed groundwater monitoring on a bi-weekly basis between January 16, 2024 and April 29, 2024 to monitor water levels in the 3 open-standpipe piezometers (OSP’s) installed during our January 9, 2024 site visit. Throughout the monitoring duration we did not observe groundwater within the OSP’s, which extended about 10, 6, and 7 feet below the ground surface in OSP-1, OSP-2, and OSP-3, respectively. The locations of the OSP’s are shown on Figure 2. CONCLUSIONS AND RECOMMENDATIONS Based on the results of our data review, site reconnaissance, subsurface explorations, engineering analysis, and our experience in the area, it is our opinion that the on-site management of stormwater runoff is feasible within the advance outwash soils. Further details are provided below. Infiltration Recommendations Test Method The 2024 SWMMWW, Volume V, Chapter 5, Section 4 provides three approved methods to estimate the design infiltration rate of site soils: 1) Large-Scale Pilot Infiltration Test, 2) Small-Scale Pilot Infiltration Test, and 3) soil grain size analysis method. Restrictions do apply to the various GCH.MattocksPlat.SR_Oct2024 October 10, 2024 page | 8 methods based on soil conditions and type of infiltration facility. We used the grain size analysis method to develop a preliminary infiltration rate. Preliminary Design Stormwater Infiltration Rate We completed soil gradation analyses on two representative soil samples from the advance outwash soils in the lower, northern portion of the site per the 2024 SWMMWW, Volume V, Chapter 5, Section 4 and in accordance with ASTM D6913. Based on our grain size analysis results, we recommend a preliminary design infiltration rate of 20.0 inches per hour be used for design of infiltration facilities within the gravelly advance outwash in the area of TP-1 and TP-101 and 4.2 inches per hour be used for design of infiltration facilities within the sandy advance outwash observed within test pits TP-102, TP-103, and TP-105. This rate includes factors of safety for site variability and number of tests (CFv = 0.5), test method (CFt = 0.4 for grain size analysis), and for potential for siltation and biofouling (CFm = 0.9). Construction Considerations If infiltration facilities are proposed, we recommend that a representative from our firm be onsite at the time of excavation of the proposed stormwater management facilities to verify that the soils encountered during construction are consistent with the soils observed in our subsurface explorations. In-situ infiltration testing shall be performed prior to and at the time of construction to verify the recommended infiltration rate and to determine if a different site-specific infiltration rate would be more appropriate for the site. It should be noted that special care is required during the grading and construction periods to avoid fine sediment contamination. This may be accomplished using an alternative stormwater management location during construction. All contractors, builders, and subcontractors working on the site should be advised to avoid allowing “dirty” stormwater or excess sediment to enter the stormwater facilities during construction and landscaping activities. No concrete trucks should be washed or cleaned in the vicinity of proposed stormwater systems. Suspended solids could clog the underlying soil and reduce the infiltration rate of the facilities. To reduce potential clogging of the infiltration systems, the infiltration system should not be connected to the stormwater runoff system until after construction is complete and the site area is landscaped, paved or otherwise protected. Temporary systems may be utilized throughout construction. Periodic sweeping of the paved areas will help extend the life of the infiltration system. Additional Services The City will likely require in-situ infiltration testing be performed in the area of proposed infiltration facilities. Once the actual size, depth, and location of the gallery has been determined using the preliminary rate provided above, we should perform in-situ Pilot Infiltration Test per the stormwater manual. Our final report will then include the final site and grading plans, updated infiltration rate based on testing, and any additional changes required by the design team. LIMITATIONS We have prepared this report for use by Garrette Custom Homes and other members of the design team for use in the design of a portion of this project. The data used in preparing this report and this report should be provided to prospective contractors for their bidding or estimating purposes only. GCH.MattocksPlat.SR_Oct2024 October 10, 2024 page | 9 Our report, conclusions and interpretations are based on our subsurface explorations, data from others and limited site reconnaissance, and should not be construed as a warranty of the subsurface conditions. Variations in subsurface conditions are possible between the explorations and may also occur with time. A contingency for unanticipated conditions should be included in the budget and schedule. Sufficient monitoring, testing and consultation should be provided by our firm during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether earthwork and foundation installation activities comply with contract plans and specifications. The scope of our services does not include services related to environmental remediation and construction safety precautions. Our recommendations are not intended to direct the contractor's methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. If there are any changes in the loads, grades, locations, configurations or type of facilities to be constructed, the conclusions and recommendations presented in this report may not be fully applicable. If such changes are made, we should be given the opportunity to review our recommendations and provide written modifications or verifications, as appropriate.    GCH.MattocksPlat.SR_Oct2024 October 10, 2024 page | 10 We have appreciated the opportunity to be of service to you on this project. If you have any questions or comments, please do not hesitate to call at your earliest convenience. Respectfully submitted, GeoResources, LLC Davis W. Carlsen, GIT Senior Staff Geologist Kyle E. Billingsley, PE Eric. W. Heller, PE, LG Senior Geotechnical Engineer Senior Geotechnical Engineer DWC:KEB:EWH/dwc Doc ID: GCH.MattocksPlat.SR Attachments: Figure 1: Site Location Map Figure 2: Site & Exploration Plan Figure 3: Site Vicinity Map Figure 4: NRCS Soils Map Figure 5: Geologic Map Appendix A: Subsurface Explorations Appendix B: Laboratory Test Results Appendix C: Infiltration Rate Calculations Approximate Site Location Figure created from the Pierce County Public GIS website (https://matterhornwab.co.pierce.wa.us/publicgis/) Not to Scale Site Location Map Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure 1 EDED EDED EDED ED ED ED ED ED ED ED ED ED ED ED ED ED @A TP-1 / PIT-1 / OSP-1 HA-1 TP-9 TP-8 TP-6 TP-4 TP-3 TP-2 TP-12 TP-11 TP-10 TP-101TP-102TP-105 TP-103TP-104 TP-106TP-107 TP-7 / OSP-3 TP-5 / OSP-2 Site & Exploration Plan Proposed Residential Plat xxx - Palisades Street Southeast Yelm, Washington PN: 21725130200 Figure 2Doc ID: GCH.MattocksPlat.F October 2024 0 80 160 24040 Feet1 in = 80 ft Legend @A Hand auger ED Infiltration test ED Test pit Preliminary Site Plan prepared by AHBL dated November 14, 2023 µ Approximate Site Location Figure created from the Thurston County online Show Me Everything Map (https://map.co.thurston.wa.us/Html5Viewer/Index.html?viewer=uMap.Main) Not to Scale Site Vicinity Map Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure 3 Approximate Site Location Figure created from the Web Soil Survey (http://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx) Soil Type Soil Name Parent Material Slopes Erosion Hazard (off -road, off-trail) Hydrologic Soil Group 2 Alderwood gravelly sandy loam Glacial drift and/or glacial outwash over dense glaciomarine deposits 8 to 15 Slight B 32 Everett very gravelly sandy loam Sandy and gravelly glacial outwash 0 to 8 A Not to Scale NRCS Soils Map Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure 4 Approximate Site Location An excerpt from the Geologic Map of the Centralia Quadrangle, Washington by Schasse, H.W. (1987) Symbol Geologic Unit Qdvg Vashon outwash gravel Qdvt Vashon till Not to Scale Geologic Map Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure 5 Appendix A Subsurface Explorations SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS GROUP SYMBOL GROUP NAME COARSE GRAINED SOILS GRAVEL CLEAN GRAVEL GW WELL-GRADED GRAVEL, FINE TO COARSE GRAVEL GP POORLY-GRADED GRAVEL More than 50% Of Coarse Fraction Retained on No. 4 Sieve GRAVEL WITH FINES GM SILTY GRAVEL GC CLAYEY GRAVEL More than 50% Retained on No. 200 Sieve SAND CLEAN SAND SW WELL-GRADED SAND, FINE TO COARSE SAND SP POORLY-GRADED SAND More than 50% Of Coarse Fraction Passes No. 4 Sieve SAND WITH FINES SM SILTY SAND SC CLAYEY SAND FINE GRAINED SOILS SILT AND CLAY INORGANIC ML SILT CL CLAY Liquid Limit Less than 50 ORGANIC OL ORGANIC SILT, ORGANIC CLAY More than 50% Passes No. 200 Sieve SILT AND CLAY INORGANIC MH SILT OF HIGH PLASTICITY, ELASTIC SILT CH CLAY OF HIGH PLASTICITY, FAT CLAY Liquid Limit 50 or more ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: SOIL MOISTURE MODIFIERS: 1. Field classification is based on visual examination of soil Dry- Absence of moisture, dry to the touch in general accordance with ASTM D2488-90. Moist- Damp, but no visible water 2. Soil classification using laboratory tests is based on ASTM D6913. Wet- Visible free water or saturated, usually soil is obtained from below water table 3. Description of soil density or consistency are based on interpretation of blow count data, visual appearance of soils, and or test data. Unified Soils Classification System Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure A-1 Test Pit TP-1 / Pilot Infiltration Test PIT-1/OSP-1 Location: Storm Tract F Approximate Elevation: 360 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.5 - Topsoil 0.5 - 1.5 ML Grey-brown sandy gravelly SILT (medium stiff, moist) 1.5 - 6.0 ML Grey sandy SILT with gravel (medium stiff, moist) 6.0 - 10.0 GP Grey GRAVEL with sand and trace silt (dense to very dense, moist) (advance outwash) Pilot Infiltration Test (PIT) performed at 4.0 feet below ground surface (BGS). Measured infiltration rate: 0.0 in/hr Terminated at 10.0 feet below the existing ground surface after completion of PIT. No caving observed at the time of excavation. Mottling observed from 1.0 to 1.5 feet BGS. Open standpipe piezometer installed at 10.0 feet BGS. Test Pit TP-2 Location: Northeast portion of Access Roadway Approximate Elevation: 384 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.5 - Topsoil 0.5 - 2.5 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till) 2.5 - 6.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till) Terminated at 6.0 feet BGS. No caving observed at the time of excavation. Mottling observed at 2.0 feet BGS. No groundwater seepage at time of excavation. Test Pit TP-3 Location: Proposed Lot 18 Approximate Elevation: 394 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.75 - Topsoil 0.75 - 3.5 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till) 3.5 - 8.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till) Terminated at 8.0 feet BGS. No caving observed at the time of excavation. No mottling observed. No groundwater seepage at time of excavation. Logged by: MAE/DEM Excavated on: January 9, 2024 Test Pit Logs Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure A-2 Test Pit TP-4 Location: Intersecting corners of proposed Lots 25, 26, 30, & 31 Approximate Elevation: 409 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.7 5 - Topsoil 0.75 - 4.0 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till) 4.0 - 6.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till) Terminated at 6.0 feet BGS. No caving observed at the time of excavation. Mottling observed from 4.0 to 5.0 feet BGS. No groundwater seepage at time of excavation. Test Pit TP-5/OSP-2 Location: Proposed Lot 23 Approximate Elevation: 401 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.5 - Topsoil 0.5 - 3.0 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till) 3.0 - 4.0 GP-GM Grey-brown sandy poorly graded GRAVEL with silt (medium dense to dense, moist) (Weathered till) 4.0 - 6.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till) Terminated at 6.0 feet BGS. No caving observed at the time of excavation. No mottling observed. No groundwater seepage at time of excavation. Open standpipe piezometer installed at 5.0 feet BGS. Test Pit TP-6 Location: Proposed Lot 38 Approximate Elevation: 420 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.5 - Topsoil 0.5 - 2.5 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till) 2.5 - 3.0 SM Grey-brown silty SAND (medium dense to dense, moist) (Weathered till) 3.0 - 6.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till) Terminated at 6.0 feet BGS. No caving observed at the time of excavation. No mottling observed. No groundwater seepage at time of excavation. Logged by: MAE Excavated on: January 9, 2024 Test Pit Logs Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure A-3 Test Pit TP-7/OSP-3 Location: Proposed Lot 1 Approximate Elevation: 360 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.5 - Topsoil 0.5 - 3.0 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Fill) 3.0 - 7.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till) Terminated at 7.0 feet BGS. No caving observed at the time of excavation. No mottling observed. Slow groundwater seepage observed at about 1.5 feet below existing grades. Open standpipe piezometer installed at 5.5 feet BGS. Test Pit TP-8 Location: Proposed Lot 4 Approximate Elevation: 405 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.5 - Topsoil 0.5 - 5.0 SM Medium brown gravelly silty SAND (medium dense to dense, moist) (Weathered till) 5.0 - 7.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till) Terminated at 7.0 feet BGS. No caving observed at the time of excavation. No mottling observed. No groundwater seepage observed at time of excavation. Test Pit TP-9 Location: Center south portion of Access Roadway Approximate Elevation: 407 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.7 5 - Topsoil 0.75 - 1.5 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till) 1.5 - 3.0 GW-GM Grey-brown sandy well-graded GRAVEL with silt (medium dense to dense, moist) (Weathered glacial till) 3.0 - 5.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till) Terminated at 5.0 feet BGS. No caving observed at the time of excavation. No mottling observed. No groundwater seepage observed at time of excavation. Logged by: MAE Excavated on: January 9, 2024 Test Pit Logs Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure A-4 Test Pit TP-10 Location: Proposed Lot 10 Approximate Elevation: 404 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.7 5 - Topsoil 0.75 - 2.0 SM Grey-brown silty SAND (medium dense to dense, moist) (Weathered glacial till) 2.0 - 5.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till) Terminated at 5.0 feet BGS. No caving observed at the time of excavation. No mottling observed. No groundwater seepage at time of excavation. Test Pit TP-11 Location: Proposed Lot 4 Approximate Elevation: 405 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.5 - Topsoil 0.5 - 4.0 SM Medium brown gravelly silty SAND (medium dense to dense, moist) (Weathered till) 4.0 - 6.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till) Terminated at 6.0 feet BGS. No caving observed at the time of excavation. No mottling observed. No groundwater seepage at time of excavation. Test Pit TP-12 Location: Proposed Lot 14 Approximate Elevation: 396 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.7 5 - Topsoil 0.75 - 3.0 GM Medium brown sandy silty GRAVEL (medium dense to dense, moist) (Weathered till) 3.0 - 5.0 GM Grey sandy silty GRAVEL (dense to very dense, moist) (Undisturbed glacial till) Terminated at 5.0 feet BGS. No caving observed at the time of excavation. No mottling observed. No groundwater seepage observed at time of excavation. Logged by: MAE Excavated on: January 9, 2024 Test Pit Logs Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure A-5 Test Pit TP-101 Location: Tract E Approximate Elevation: 360 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.75 - Topsoil 0.75 - 5 ML Brown-grey sandy SILT with some gravel (stiff, moist) (undocumented fill) 5 - 12.5 GP Grey GRAVEL with sand and trace silt (dense to very dense, moist) (advance outwash) Terminated at 12.5 feet BGS. No caving observed at the time of excavation. No mottling observed. Slow groundwater seepage observed at approximately 11 feet BGS Test Pit TP-102 Location: Proposed Tract D Approximate Elevation: 368 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 1.0 - Topsoil 1.0 - 4.25 SM Brown silty SAND with some gravel (medium dense, moist) (weathered advance outwash) 4.25 - 11.5 SP-SM Grey gravelly poorly graded SAND with some silt, occasional thin silt lenses (dense, moist) (advance outwash) Terminated at 11.5 feet BGS. No caving observed at the time of excavation. No mottling observed. No groundwater seepage at time of excavation. Logged by: DC Excavated on: February 7, 2024 Test Pit Logs Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure A-6 Test Pit TP-103 Location: Proposed Tract D Approximate Elevation: 370 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 1.0 - Topsoil 1.0 - 3.5 SM Brown silty SAND with some gravel (medium dense, moist) (weathered advance outwash) 3.5 - 10.5 GM Grey sandy silty GRAVEL (dense to very dense, moist) (advance outwash) Terminated at 10.5 feet BGS. No caving observed at the time of excavation. No mottling observed. No groundwater seepage at time of excavation Test Pit TP-104 Location: Proposed Tract D Approximate Elevation: 376 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.75 - Topsoil 0.75 - 3.0 SM Brown gravelly silty SAND (medium dense, moist) (weathered glacial till) 3.0 - 9.5 SM Grey gravelly silty SAND (very dense, moist) (glacial till) Terminated at 9.5 feet BGS. No caving observed at the time of excavation. Mottling observed at approximately 2.5 feet BGS. No groundwater seepage at time of excavation. Refusal in excavation Logged by: DC Excavated on: February 7, 2024 Test Pit Logs Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure A-7 Test Pit TP-105 Location: Northern road area Approximate Elevation: 380 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 1.0 - Topsoil 1.0 - 3.5 SM Brown silty SAND with some gravel (medium dense, moist) (weathered advance outwash) 3.5 - 7.5 SM Grey fine silty SAND with some gravel (medium dense, moist) (advance outwash) 7.5 - 11.5 GM Grey sandy silty GRAVEL (dense to very dense, moist) (advance outwash) Terminated at 11.5 feet BGS. No caving observed at the time of excavation. Slight mottling observed at 7 feet BGS. No groundwater seepage at time of excavation Test Pit TP-106 Location: Proposed Lot 22 Approximate Elevation: 396 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 1.0 - Topsoil 1.0 - 3.25 SM Browns silty SAND with some gravel, buried debris (loose to medium dense) (undocumented fill) 3.25 - 5.0 SM Brown gravelly silty SAND (medium dense, moist) (weathered glacial till) 5.0 - 9.5 SM Grey gravelly silty SAND (very dense, moist) (glacial till) Terminated at 9.5 feet BGS. No caving observed at the time of excavation. Mottling observed at approximately 4.5 feet BGS. No groundwater seepage at time of excavation. Refusal in excavation Logged by: DC Excavated on: February 7, 2024 Test Pit Logs Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure A-8 Test Pit TP-107 Location: Proposed lot 29 Approximate Elevation: 404 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.5 - Topsoil 0.5 - 2.0 SM Brown gravelly silty SAND (medium dense, moist) (weathered glacial till) 2.0 - 9.0 SM Grey gravelly silty SAND (very dense, moist) (glacial till) Terminated at 9.0 feet BGS. No caving observed at the time of excavation. Slight mottling observed at 2 feet BGS. No groundwater seepage at time of excavation Logged by: DC Excavated on: February 7, 2024 Test Pit Logs Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure A-9 Hand Auger HA-1 Location: Existing stormwater facility Approximate Elevation: 357 feet (lidar-derived, Thurston 2021 DTM 53, NAVD88) Depth (ft) Soil Type Soil Description 0.0 - 0.25 - Topsoil 0.25 - 3.5 GM Grey silty GRAVEL with some sand (very dense, moist) (advance outwash) Terminated at 3.5 feet BGS. No caving observed at the time of excavation. No mottling observed at time of excavation No groundwater seepage at time of excavation Logged by: DC Excavated on: February 7, 2024 Test Pit Logs Proposed Residential Plat xxx – Palisades Street Southeast Yelm, Washington PN: 21725130200 Doc ID: GCH.MattocksPlat.F Oct 2024 Figure A-10 Appendix B Laboratory Test Results Th e s e r e s u l t s a r e f o r t h e e x c l u s i v e u s e o f t h e c l i e n t f o r w h o m t h e y w e r e o b t a i n e d . T h e y a p p l y o n l y t o t h e s a m p l e s t e s t e d a n d a r e n o t i n d i c i t i v e o f a p p a r e n t l y i d e n t i c a l s a m p l e s . Tested By: Checked By: Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 13.2 7.2 2.8 6.7 18.7 51.4 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 Test Results (ASTM D 6913 & ASTM D 1140) Opening Percent Spec.*Pass? Size Finer (Percent)(X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-1, S-2 Sample Number: 104657 Depth: 4' Client: Project: Project No:Figure Sandy SILT with gravel (ML) 2.0 1.5 1.25 1 .75 .5 0.375 #4 #10 #20 #40 #60 #100 #200 100.0 91.2 91.2 91.2 86.8 84.1 82.6 79.6 76.8 74.0 70.1 65.8 60.5 51.4 NP NV NP ML A-4(0) 23.0729 15.8081 0.1443 Natural Moisture: 22.9% 1/9/24 1/18/24 MAW KEB PM 1/9/24 Garrette Custom Homes Proposed Residential Plat GarretteCustomHomes.MattocksPlat PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-1 Th e s e r e s u l t s a r e f o r t h e e x c l u s i v e u s e o f t h e c l i e n t f o r w h o m t h e y w e r e o b t a i n e d . T h e y a p p l y o n l y t o t h e s a m p l e s t e s t e d a n d a r e n o t i n d i c i t i v e o f a p p a r e n t l y i d e n t i c a l s a m p l e s . Tested By: Checked By: Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 32.6 23.7 9.2 12.8 10.8 10.9 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 Test Results (ASTM D 6913 & ASTM D 1140) Opening Percent Spec.*Pass? Size Finer (Percent)(X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-5, S-2 Sample Number: 104658 Depth: 3.5' Client: Project: Project No:Figure Poorly graded GRAVEL with silt and sand (GP-GM) 2.0 1.5 1.25 1 .75 .5 0.375 #4 #10 #20 #40 #60 #100 #200 100.0 93.8 89.6 76.8 67.4 58.3 55.6 43.7 34.5 27.9 21.7 17.5 14.2 10.9 NP NV NP GP-GM A-1-a 32.0590 29.0710 13.9775 6.6497 1.0999 0.1709 Natural Moisture: 10.4% 1/9/24 1/18/24 MAW KEB PM 1/9/24 Garrette Custom Homes Proposed Residential Plat GarretteCustomHomes.MattocksPlat PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-2 Th e s e r e s u l t s a r e f o r t h e e x c l u s i v e u s e o f t h e c l i e n t f o r w h o m t h e y w e r e o b t a i n e d . T h e y a p p l y o n l y t o t h e s a m p l e s t e s t e d a n d a r e n o t i n d i c i t i v e o f a p p a r e n t l y i d e n t i c a l s a m p l e s . Tested By: Checked By: Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 39.8 24.2 7.0 11.9 12.0 5.1 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 Test Results (ASTM D 6913 & ASTM D 1140) Opening Percent Spec.*Pass? Size Finer (Percent)(X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-9, S-1 Sample Number: 104659 Depth: 2' Client: Project: Project No:Figure Well-graded GRAVEL with silt and sand (GW-GM) 2.0 1.5 1.25 1 .75 .5 0.375 #4 #10 #20 #40 #60 #100 #200 100.0 87.1 67.1 64.0 60.2 48.4 44.7 36.0 29.0 22.9 17.1 12.1 8.5 5.1 NP NV NP GW-GM A-1-a 39.3352 37.3647 18.8871 13.6053 2.3410 0.3411 0.1903 99.25 1.52 Natural Moisture: 6.4% 1/9/24 1/18/24 MAW KEB PM 1/9/24 Garrette Custom Homes Proposed Residential Plat GarretteCustomHomes.MattocksPlat PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-3 Th e s e r e s u l t s a r e f o r t h e e x c l u s i v e u s e o f t h e c l i e n t f o r w h o m t h e y w e r e o b t a i n e d . T h e y a p p l y o n l y t o t h e s a m p l e s t e s t e d a n d a r e n o t i n d i c i t i v e o f a p p a r e n t l y i d e n t i c a l s a m p l e s . Tested By: Checked By: Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 7.0 23.5 10.6 16.2 22.2 20.5 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 Test Results (ASTM D 6913 & ASTM D 1140) Opening Percent Spec.*Pass? Size Finer (Percent)(X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-11, S-1 Sample Number: 104660 Depth: 1' Client: Project: Project No:Figure Silty SAND with gravel (SM) 1.25 1 .75 .5 0.375 #4 #10 #20 #40 #60 #100 #200 100.0 95.9 93.0 86.0 82.0 69.5 58.9 50.4 42.7 35.1 27.8 20.5 NP NV NP SM A-1-b 15.8019 11.8879 2.2367 0.8152 0.1770 Natural Moisture: 20.8% 1/9/24 1/18/24 MAW KEB PM 1/9/24 Garrette Custom Homes Proposed Residential Plat GarretteCustomHomes.MattocksPlat PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-4 Th e s e r e s u l t s a r e f o r t h e e x c l u s i v e u s e o f t h e c l i e n t f o r w h o m t h e y w e r e o b t a i n e d . T h e y a p p l y o n l y t o t h e s a m p l e s t e s t e d a n d a r e n o t i n d i c i t i v e o f a p p a r e n t l y i d e n t i c a l s a m p l e s . Tested By: Checked By: Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 16.1 23.7 12.1 16.5 15.9 15.7 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 Test Results (ASTM D 6913 & ASTM D 1140) Opening Percent Spec.*Pass? Size Finer (Percent)(X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-8, S-1 Sample Number: 104663 Depth: 2' Client: Project: Project No:Figure Silty SAND with gravel (SM) 1.25 1 .75 .5 0.375 #4 #10 #20 #40 #60 #100 #200 100.0 93.1 83.9 74.9 71.9 60.2 48.1 39.2 31.6 25.7 20.8 15.7 NP NV NP SM A-1-b 23.1091 19.7827 4.7072 2.3489 0.3707 Natural Moisture: 15.9% 1/9/24 1/18/24 MAW KEB PM 1/9/24 Garrette Custom Homes Proposed Residential Plat GarretteCustomHomes.MattocksPlat PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-5 Th e s e r e s u l t s a r e f o r t h e e x c l u s i v e u s e o f t h e c l i e n t f o r w h o m t h e y w e r e o b t a i n e d . T h e y a p p l y o n l y t o t h e s a m p l e s t e s t e d a n d a r e n o t i n d i c i t i v e o f a p p a r e n t l y i d e n t i c a l s a m p l e s . Tested By: Checked By: Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 69.6 13.8 2.4 5.0 5.2 4.0 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 Test Results (ASTM D 6913 & ASTM D 1140) Opening Percent Spec.*Pass? Size Finer (Percent)(X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-101, S-1 Sample Number: 104798 Depth: 8' Client: Project: Project No:Figure Poorly graded GRAVEL (GP) 3.0 2.5 2.0 1.5 1.25 1 .75 .5 0.375 #4 #10 #20 #40 #60 #100 #200 100.0 79.2 68.0 47.1 44.9 34.9 30.4 23.7 20.8 16.6 14.2 11.6 9.2 7.3 5.7 4.0 NP NV NP GP A-1-a 70.5107 67.5324 45.7374 40.3640 18.3467 2.8544 0.5352 85.46 13.75 Natural Moisture: 3.4% 2/7/24 2/15/24 MAW KEB PM 2/7/24 Garrette Custom Homes Proposed Residential Plat GarretteCustomHomes.MattocksPlat PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-6 Th e s e r e s u l t s a r e f o r t h e e x c l u s i v e u s e o f t h e c l i e n t f o r w h o m t h e y w e r e o b t a i n e d . T h e y a p p l y o n l y t o t h e s a m p l e s t e s t e d a n d a r e n o t i n d i c i t i v e o f a p p a r e n t l y i d e n t i c a l s a m p l e s . Tested By: Checked By: Particle Size Distribution Report PE R C E N T F I N E R 0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 10.7 17.7 7.1 20.4 37.5 6.6 6 i n . 3 i n . 2 i n . 1½ i n . 1 i n . ¾ i n . ½ i n . 3/ 8 i n . #4 #1 0 #2 0 #3 0 #4 0 #6 0 #1 0 0 #1 4 0 #2 0 0 Test Results (ASTM D 6913 & ASTM D 1140) Opening Percent Spec.*Pass? Size Finer (Percent)(X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-102, S-2 Sample Number: 104799 Depth: 8.5' Client: Project: Project No:Figure Poorly graded SAND with silt and gravel (SP-SM) 1.25 1 .75 .5 0.375 #4 #10 #20 #40 #60 #100 #200 100.0 91.2 89.3 83.3 78.3 71.6 64.5 56.2 44.1 27.5 14.2 6.6 NP NV NP SP-SM A-1-b 23.7022 13.8854 1.2172 0.5534 0.2702 0.1565 0.1127 10.80 0.53 Natural Moisture: 7.3% 2/7/24 2/15/24 MAW KEB PM 2/7/24 Garrette Custom Homes Proposed Residential Plat GarretteCustomHomes.MattocksPlat PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) GeoResources, LLC Fife, WA B-7 Appendix C Infiltration Rate Analysis Soil Grain Size Analysis Method Procudure based on 2019 SWMMWW, Volume V, Chapter 5, V-5.4 K sat = 10^(-1.57 + 1.90D10 + 0.015D60 - 0.013D90 - 2.08Ffines)(provides Ksat in cm/s) K sat = [10^(-1.57 + 1.90D10 + 0.015D60 - 0.013D90 - 2.08Ffines)]*1417 (provides Ksat in in/hr) I.D.Expl.Depth (ft) Layer Thickness (ft) D10 D60 D90 Ffines Individual Ksat (cm/s) Equivalent Ksat (in/hr) 104798 TP-101 8 0.535 45.737 70.511 0.040 0.136 192.518 Effective Average Hydraulic Conductivity, K equiv 192.518 Har. Mean Based on either:192.518 Lowest 1)Average Ksat determined using harmonic mean 192.000 To Use 2)Lowest conductive layer, if within 5ft of bottom of pond Site variability and number of tests (CFv) 0.33 to 1.0 Factor to use for calculations 0.5 Test Method (CFt) 0.75 0.5 0.4 Factor to use for calculations 0.4 Siltation and bio-buildup (CFm) 0.90 Factor to use for calculations 0.9 Idesign = Imeasured * Ftesting * Fgeometry *Fplugging 34.56 in/hr Preliminary Design Value 20.00 in/hr April 2024 Figure C-1 Yelm, Washington PN: 21725130200 DocID: GCH.MattocksPlat.ksat kequiv= Large-scale PIT 90% of design capacity Small-scale PIT Other small-scale (e.g. Double ring, falling head) & Grain Size Infiltration Rate Analysis - outwash gravel xxx - Palisades Street Southeast 2024 Stormwater Management Manual for Western Washington Garrette Custom Homes - Mattocks Plat Yelm, Washington Massman Calculation Sheet Proposed Residential Plat Sample Information Sieve Data Unfactored Rate Stormwater Report The Reserve at Palisades 2220348.10 Appendix D Existing Conditions D-1.................... Palisades West Final Storm Drainage Report D-2.................... Existing Well and Septic FORRESTER HEIGHTS PHASE Yelm, WA I FINAL STORM DRAINAGE REPORT 2"C:. SceSM l-i-rA l_ 5CA""ev 7/or/a-7 Prepared for. FHl LLC 4200 Sixth Avenue SE, Suite 301 Lacey, WA 98503 (360) 493-6002 Prepared by: aConsu Ling Engineers 4200 Sixth Avenue SE, Suite 309 Lacey, WA 98503 (360) 292-7230 January 9, 2007 RECF JAN ] 2 IU0 I1 2Nn Sub Final Drainage Report Forrester Heights Phase 1 Yelm, Washington January 9, 2007 Project Information Project: Forrester Heights Phase 1 Prepared for: FH1 LLC Contact: Dan Lee 4200 6th Ave. SE, Ste. 301 Lacey, WA 98503 (360) 493-6002 Reviewing Agency Jurisdiction: City of Yelm, Washington Project Number: Project Contact: James E. Gibson Project Engineer Prepared by: EPFF Consulting Engineers 4200 6th Ave. SE, Ste. 309 Lacey, WA 98503 (360) 292-7230 FAX (360) 292-7231 Contact Mark Steepy, P.E. EPFF Project: 406050 PROJECT ENGINEERS CERTIPIGAnON: I hemby mRily that this Final Drainage Report for the Forrester Heights Ph. 1 Plat m Yebn Weshm&. has ben. prepared by me or order my auperviei.. and meats the inte.t ofthe City oMlm D) .]opme.tGuidohnes end WtshhwW.State Depatt.meat of Emlogy(WSDOE) SW.Wr Mmageme.t Ma..al for the Puget Somd Beni. u.lees.oted otherwise, eud..I standards ofeagi..rin, practice. I understand that the juriedictio. dme.ot end will not assume liability t r the eulnciancy, wdabMV, ar perfarmence.fdreionge ftdifties designed for this development-aaaftae. EXPIRES 2/270 7 IPFF Consulting Engineers i January 9, 2007 TABLE OF CONTENTS PART I STORM DRAINAGE REPORT I SECTION I - PROPOSED MOSECT DESCRIPTION._ ................ . .............. ...................... I SECTION 2 - EJUSUNGOONDITIONS - .............. ....... . ... . ............ ........................... -- 4 SECTION 3 - INFILTRATION RATESWILII REPORT ..................... . . ................ . .... 4 SbCnON4- IFELLSAN13SEPTICSYSTFMS SECTION 5 - FUEL TANKS.......-- ......................... . . . ............... . .. . ............... —4 SECTION 6, SUB -BASIN DESCRIPTION . ............................................................ - .................. 5 SECTION 7 - ANALYS]SOFIWYEARFLOOD ..... . .......................................................... 5 SECTION 8 - AESTHETIC CONSIDERATIONS FOR FACILPTIES .....................................5 SECTION 9 ............... . . ---.5 SECTION 10 - COVENANTS, DEDICATIONS, EASEMENUS, ............ ... ... . ......... PART IT - EROSION CONTROL REPORT 6 SECTION I- CONSTRUCTION SEQUENCE AND PROCEDURE........_.........._ ....................6 SECTION 2 - TRAPPING SEDlloIEI4T ........................... -- ................................. . ......... . ........... 6 SECTION3- PERMANENT EROSION CONTROL & SITE RESTORATION ........ . .. ........ 7 SECTION 4. GBOTTKIENICAL ANALYNISAND REPORT_.......__ ............... ............. 7 SECTION 5 - INSPECTION SEQUENCE._ . . ........... .... . .......... . .................................................. 7 SECTION 6 - CONTROL OF POLLUTANTS OTHER THAN SEDMIEN TS ........ . ................. 7 PARTHI-MAINTENIANCEPLAN— --a SECTION I- REQUIREDMAINTENANCH, . . . ............................. . ... . ...... . . .... to SEC71ON2- .... . . . . . . .............. . .......... . ... . ..... 17 SHCTION3- VEGETATION MANAGEMENT PLAN..._ ....................................... . ...... . ........ 17 SECTION4- SOURCE CONTROL...._..._..........._ ................... . ................ ........................... . . 17 APPENDICES Appcu I - FmI Dmia� CelculaEons Ap,e.&x II - Fi Dmaage e TESL Pk App.d. Iff -Fm ty S—, I. AMm TV FEMA FIRM Map APpeedix V - Vimmty Map KPFF Consulting Engle ii January 9, 2007 Part I Preliminary Storm Drainage Report Forrester Heights Final Drainage Report KPFF Consulting Engineers PART I STORM DRAINAGE REPORT SECTION 1 - PROPOSED PROJECT DESCRH'TION Project Proponent: PHI LLC 4200 6th Avenue SE, Suite 301 Lacey, WA 98503 (360)493-6002 Parcel Numbers: 21725130300 Total Site Area: 10.92 Acres Zoned: R-4 Site Address: 15026 State Hwy 507, Yelm, WA 98597 Required Permits: Grading, Utility, Building, Plumbing, Electrical, Mechanical, etc. Section, Township, Range: Section 25, Township 17 North, Range 1 East, W.M., Thurston County, WA Site Location: The site is located in Yehn, Washington and is bordered on the north by State Hwy 607 and situated westerly of the Hawks Landing subdivision. Project Overview: The proposal is to develop the 10.92 acres into 24 lot single-family residential subdivision The development of the proposed site will be constructed in one phase and will include appropriate erosion control measures as needed, grading, storm drainage improvements and extension of underground utilities including water and sanitary sewer. Storm Drainage Improvements The completed project will create approximately 1.62 acres of new impervious roadway and sidewalk, 8.27 acres of pervious area (majority of which will remain undisturbed), 0.28 acres of lot impervious area, 0.83 air of roof impervious area. All project impervious areas (roads, walks, roofs) are accounted for below KPFF Consulting Engineers i January 9, 2007 Forrester Heights Final Drainage Report KPFF Conso ing Engineers Table 1 Post -Development Basin Area Summary Driveways (500 sf per lot) Roofs Area (1,500 sf roof per lot) Impervious Roadway Impervious Sidewalk Undisturbed Pervious Basin A Basin B Basin C Total 0.28 ac** 0.00ac 0.00 ac 0.28 ac 0.45 ac 0.37 ac 0.00 ac 0.83 ac 1.46 ac* 0.00 ac 0.00 ac 1.46 ac* 0.16 ac 0.00 ac 0.00 ac 0.16 ac 0.00 ac 2.50 ac 1.49 ac 3.99 ac I Total 4.28 ac 4.86 ac 1.49 ac 10.63 ac I ** Includes driveways in Basin B that drain to Basin A *Includes that portion of the roadway that is constructed on parcel 21725130200 and frontage improvements along SR 507. Stormwater Treatment: Stormwater treatment design requirements are based on the 1992 edition of the WSDOE Stormwater Management Manual. StortnShed was used to size the treatment facilities. Final treatment calculations are provided in Appendix I. Only a small amount of the pervious surfaces in the basin is tributary to the treatment facilities, and is unlikely to generate appreciable runoff due to high soil permeability. Open space in eastern part of property will be heavy vegetated. By considering all pervious surfaces in our calculations we input additional safety margin. For the purposes of this study whole site is divided into three basins. Sub Baisn'A': Sub Basin'A' includes all of the access road and sidewalks within phase 1 of the development. The impervious area of Basin A includes that portion of the roadway that is located on parcel 21725130200 and all of the driveways for all 24 lots within the plat. Runoff from the roadway and impervious lots areas will sheet flow to a series of street side catch basins and be directed toward a wet pond for treatment and storage, and into infiltration pond for infiltration to groundwater. The DOE Manual requu es that runoff from 6-month 24-hour atom be treated. The wet pond was sized to exceed the minimum treatment requirements of the DOE Stormwater Manual. Sub Basin B': Sub Basin B' includes 11 lots, which will slope away from the roadway within Basin A, and the open space on the eastern portion of the site the roadway. The areas of the driveways are included in Basin A for treatment. It is very unlikely that this basin will KPFF Consulting Engineers January 9, 2007 Fonesler Heights Final Drainage Report KPFF Consulting Engineers produce any appreciable runoff due to high soil's permeability rates of the basin does not require treatment for the runoff. Sub Basin'C': Sub Basin `C' includes the remain area of the site which includes future lots of Phase 2 and the open space adjacent to lot 24 all of which slopes away from the roadway within Basin A and the open space in the eastern part of the site. It is very unlikely that this basin will produce any appreciable runoff due to high soil's permeability rates which is pending City's annexation process of adjacent parcel will be part of Phase II. All new roadways that will be constructed in this area will be addressed in the drainage report for Phase 2. ROOF RUNOFF: Roof runoff from new construction will be muted to individual onsite drywells. The drywells shall be sized per the DOE Stormwater Manual based on an average mof size of 1,500 sf. As all lots shall have drywells based on Class B soils. No treatment required for clean impervious surfaces. Stormwater Storage/Infiltration: Stormwater storage and infiltration requirements are based on the 1992 edition of the WSDOE Stormwater Management Manual. Preliminary storage and infiltration calculations are provided in Appendix I. Roof runoff from individual lots will be rooted to drywells located within respectful lots. Sub-basin'Al': Stormwater runoff conveyed through the wet pond for treatment and storage will discharge into infiltration pond for infiltration to groundwater. WSDOE Stormwater Management Manual requirements for infiltration pond are such that it should be able to infiltrate 100-year/74-hour storm event within 48 hours. Storao a Capacity Summary Impervious Area Disturbed Pervious Area Storage (1) Reouired Storage Provided Basin A 1.90 ac 1.93 ac 5 547 cf 15,630 cf TOTAL 1.90 ac 1.88 ac 547 cf 16 830 of (1) Based on design infiltration rate of 20-inehes/hour using StormShed modeling software for the 100-year storm event KPFF Consulting Engineers 3 January 9, 2007 Forrester Heights Final Drainage Report KPFF Consulting Engineers SECTION 2 - EXISTING CONDITIONS ' The site is 10.92 acre trapezoidal in shape with 80 feet fronting SR 507. The site slopes in the northeast direction with low elevations of approximately 358 ft. located close the northern property line. The highest elevation of 420 ft is at the center of the site. The site is occupied by two mobile homes and one barn (to be removed) located centrally. The site has a light density of second growth Fir trees in the southeast portion of the site. The remainder of the site is covered with a light density of Scotch Broom growth with 1 indigenous field grasses. The project site is bounded by residential property to the south and west and by SR-507 to the north. On site soils are well drained and formed in glacial outwash There are no creeks, lakes, ponds, springs, wetlands, ravines, gullies or other environmentally sensitive areas identified onsite or down gradient of the subject property. East part of property contains 35% slope. The site is located in an aquifer sensitive area, according to the 1986 Thurston County Comprehensive Plan M-8. The site is not located in a wellhead protection area. SECTION 3 - INFILTRATION RATES/SOHS REPORT The Soil Conservation Service (SCS) Soil Survey of Thurston County classifies onsite soils as Spanaway (110) series. The design infiltration rate of 20 inches per hour was assumed for the purposes of this study. This is a conservative rate based on actual infiltration rates observed in the field. SECTION 4 -WELLS AND SEPTIC SYSTEMS 1 Onsite mobile homes are served by existing onsite well. This well will be abandoned in accordance with Department of Ecology standards. A Onsite mobile homes are served by existing septic system. These septic systems will be removed in accordance with Thurston County Department of Health standards. SECTION 5 - FUEL TANKS No fuel tanks were located during KPFF's site inspection. Additionally, a review of the DOE's Leaking Underground Storage Tank (LUST) list did not indicate any existing or abandoned fuel tanks on the project site. KPFF Consulting Engineers January 9, 2007 Forrester Heights Final Drainage Report KPFF Consulting Engineers SECTION 6 - SUB -BASIN DESCRIPTION The project site is located in the Thompson Creek Drainage Sub -Basin, Nisqually River Drainage Basin per Thurston County Comprehensive Map MA. During KPFF's site investigation and soils analysis, it appeared that all onsite stormwater runoff is contained onsite and infiltrated back into the groundwater, which is typical of the site's soil classification. All onsite stormwater runoff will be contained and infiltrated onsite. There does not appear to be any significant existing offaite drainage to the property As discussed previously, the proposed development has been divided into three drainage basins. The facilities in these basins consist of wet ponds to provide stormwater treatment and storage, and infiltration ponds to provide infiltration to groundwater. No hazardous materials handling is anticipated in the area tributary to the storm drainage facilities. SECTION 7 - ANALYSIS OF 100-YEAR FLOOD This project does not lie adjacent to or contain a stream onsite and has not been identified as a 100-year flood hazard area. A FEMA FIRM Map is included in Appendix V. There is no available area for an overflow from the infiltration pond. Therefore, the pond was calculated and the pond was then increased by 25% to handle those storms above the 100-year event. SECTION S - AESTHETIC CONSIDERATIONS FOR FACILITIES All disturbed pervious areas will be vegetated and landscaped. SECTION 9 - DOWNSTREAM ANALYSIS AND FACILITY SIZING Preliminary sizing calculations for the pmject's stormwater treatment, storage, and infiltration facilities are provided in Appendix I of this report. All calculations correspond to the Preliminary Grading, Drainage and TESC Plan, which can be found in Appendix If of this report. Since all stormwater will be infiltrated onsite, a downstream analysis was deemed unnecessary. SECTION 10 - COVENANTS, DEDICATIONS, EASEMENTS Onsite drainage facilities including pipes, wet ponds and infiltration ponds will require routine maintenance. The maintenance manual prepared for the project will list the maintenance requirements. A copy of the completed Maintenance Manual can be supplied to the City upon completion of the project. KPFF Consulting Engineers 5 January 9, 2007 Part H Erosion Control Report Forrester Heights Final Drainage Report KPFF Consulting Engineers PART II — EROSION CONTROL REPORT SECTION 1 - CONSTRUCTION SEQUENCE AND PROCEDURE The proposed commercial development will include site grading and erosion control measures designed to contain silt and soil within the project boundaries during construction until permanent vegetation and site improvements are in place. Erosion/sedimentation control shall be achieved by a combination of structural/vegetative cover measures and construction practices tailored to fit the site. Best Management Practices (BMP's) will be employed to properly clear and grade the site and to schedule construction activities. Before any construction begins onsite, erosion control facilities shall first be installed. The planned construction sequence is as follows: 1. Schedule preconstruction conference with the city, contractor, project engineer, and construction -staking surveyor. 2. Install rock construction entrance. Use 4" to 8" diameter spells with 12" minimum depth. 3. Install erosion control features shown on the plans. 4. Clear site (grubbing and rough grading). 5. Install straw over area that were disturbed during grading of site. 6. Maintain equipment and water supply for dust control. 7. Designate an area for washing concrete trucks to control the runoff and eliminate entry into the storm drainage system. 8. Install underground utilities (water, sewer, and storm). 9. Provide inlet protection around all new catch basins. 10. Construct roadway and install landscaping, sod and/or seed, and mulch all disturbed areas. 11. Maintain all erosion control facilities until the entire site is stabilized and silt runoff ceases. SECTION 2 - TRAPPING SEDIMENT Filter fabric fencing will be installed to trap sediment before runoff exits the site. In addition, inlet protection will be installed around all existing and new catch basins to filter out sediment before runoff enters the storm system. A stabilized construction entrance will be installed to prevent construction vehicles from tracking soil onto roadways. If sediment is tracked offsite, it shall be swept or shoveled from paved surfaces on a daily basis, so that it is not washed into existing catch basins or other storm drainage facilities. During the rainy season from November 1 through March 31, the contractor must cover any disturbed areas greater that 5,000 SF in size if they will be unworked for more than 12 hours. Mulch, sodding, or plastic covering shall he used to prevent erosion in these areas. KPFF Consulting Engineers 6 January 9, 2007 Forrester Heights Final Drainage Report KPFF Consulting Engineers SECTION 3 - PERMANENT EROSION CONTROL A SITE RESTORATION All disturbed areas will be paved with asphalt, covered by buildings, or landscaped with grass, shrubbery, or trees per the landscaping plans. SECTION 4. GEOTECRNICAL ANALYSIS AND REPORT None of the storm drainage facilities are located near the top of a steep slope. Therefore, a geotechnical analysis for slope or soil stability was deemed unnecessary, take into consideration that steep slopes are present onsite, geotechnical analysis will be provided with final drainage report. SECTION 5 - INSPECTION SEQUENCE In addition to required City inspections, the Project Engineer will inspect facilities related to stormwater treatment, erosion control, storage, and conveyance during construction. At a minimum, the following items shall be inspected at the time specified: 1. The erosion control facilities shall be inspected before the start of clearing and grading to ensure the following structures are in place: a. Construction Entrance b. Filter Fabric Fences c. Inlet protection of new catch basins 2. The conveyance systems will be inspected after construction of the facilities, but before project completion to ensure the following items are in working order: a. Pavement Drainage b. Catch Basins c. Conveyance Piping d. Roof Drain Piping 3. The infiltration galleries shall he inspected during construction to ensure that the facility is constructed to design specifications. 4. The permanent site restoration measures shall be inspected after landscaping is completed. A final inspection shall be performed to verify final grades, settings of structures and all necessary information to complete the Engineer's Construction Inspection Report Form. This form must be completed prior to final public works construction approval. �IQI]�[;JZK4.`YYi71)IC173717iI (\IY V:\�Y'1.�15Y7�'lIY'./:\� 1 I�I�V1; The contractor will be required to designate a washdown area for concrete trucks as well as a temporary stockpile area for construction debris. Catch basin inlet protection and filter fabric fencing shall remain in place until construction on the site is complete. KPFF Consulting Engineers January 9, 2007 Part III Maintenance Plan Forrester Heights Final Drainage Reporl KPFF Conwllirg Engineers PART III — MAINTENANCE PLAN INSTRUCTIONS FOR MAINTENANCE OF STORM DRAINAGE FACILITIES The following pages contain maintenance needs for most components that are part of the drainage system. A checklist should be completed for all system components according to the following schedule: I. Monthly from November through April 2. Once in late summer (preferably September) 3. After any major storm (use 1" in 24-hours as a guideline) items marked "S' only. Use photocopies of these pages and check off the problems identified with each inspection. Add comments on problems found and actions taken. Keep these "checked" sheets in a file, as they will be used to write the annual report (due in May of each year). Some items do not need to be checked with every inspection. Use the suggested frequency at the left of each item as a guideline for the inspections. The City of Yelm is available for technical assistance. Do not hesitate to call, especially if it appears that a problem may exist. KPFF Consulting Engineers e January 9, 2007 Forrester Heighls Final Drainage Report KPFF Consulling Erxyneers COVER SHEET Inspection Period: Number of Sheets Attached: Date hlspec W: Name of Inspector: Inspector's Signature: I KPFF Consulting Engineers g January 9, 2007 Forrester Heights Final Drainage Report KPFF Consulting Engineers SECTION 1 - REQUIRED MADMENANCE The drainage facilities will require occasional maintenance. The checklists below are the minimum maintenance requirements and inspection frequencies. Maintenance Checklist for Conveyance System (Pipes and Swales) Frequency Drainage J Problem Conditions to Check For Conditions That Should System Reri,d Exist Feature M.S. Pipes J Sediment & Accumulated sediment that Pipe cleared of all debris exceeds 20% of the diameter of sediment and debris. the pipe. M J Vegetation Vegetation that reduces free All vegetation removed so movement of water through pipes water flows freely. A J Damaged Protective coating is damaged; Pipe repaired in replaced. (rusted, rust is causing more than 50% bent or deterioration to any pan ofpipe. crushed) M J Anydem that significantly Pipe repaired o replaced. impedes flow (i.e., decreases the cross Section area of pipe by more then 20%). M J Pipe has major cracks or tears Pipe repaired in replaced. allowing groundwater leakage. M.S. Swales Trash & Dumping of yard wastes such as Remove trash and debris debris grass clippings and branches into and dispose as prescribed Swale. Accmnulatioa of non- by CityWaste degradable materials such as Management Section, glass, plastic, metal, foam and comod paper. M Sediment Accumulated sediment that Swale cleaned of all buildup exceeds 20%ofthe design depth sediment and debris so that it matches design. M Vegetation Grass cover ta some and weedy Aerate soils and reseed not or areas are overgrown with and mulch bare areas. growing or woody vegetation. Maintain grass height at a overgrown mimmrm of 6" for best stain ter treatment. Remove woody growth, recomaa and reseed as necessary. M Conversion Swale has been filled in or li pos able, speak with byownerto blockedbyshed,woodpile, owner and request that incompatibl shrubbery, etc. swale area be restored. e use Contact Cityto report problem if no rectified wlrmtarily. A Swale does Water stands in Swale or flow A survey maybe needed not drain velocity is very slow. Stagnation in check grades. Grades KPFF Consulting Engineers 10 January 9, 2007 IForrester Heights Final Drainage Report KPFF Consulting Engineers I Frequency Drainage 4 Problem Conditions to Check For Conditions That Should System Req.d FAst Feature occurs. need to be in 1%range if possible. If grade is less Um 7%y tmdendlalns may need m be tustalled. ffYmww whether a emblem=i plw am t the luiediatlm mded fm twhmul.admac C.® Kry: A=Amuel(A hm Apnlpre h M ahtoemly (rz cMiule) S-Aflcr nvjm Ymw I KPFF Consulting Engineers tt January 9, 2007 IForrester Heights Final Drainage Report KPFF Consulting Engineers ' ATTACHMENT "A" (CONTINUED) Maintenance Checklist for Catch Basins and Inlets Fnxryency lhainage J Problem Conditions to Check For Conditions Thal System Should Exist Feature M.S. General J Trash, debris and Trash or debris in front of No hash or debris sediment in or on the catch basin opening is located basin blocking rapacity by more immediately in than 10%. front ofcatch basin opening. Gate is kept clean and allows water to enter. M J Sediment or debris (in the No sediment or basin) that exceeds 1/3 the debris in the catch depth from the bottom of basin. Catch basin basin to invert of the lowest is dug out and pipe into or out ofthe clean. basin. M_S- J Trash or debris in any idet bidet and outlet or pipe blocking more than pipes free oftrash 1/3 of its height. is, debris. M J Structural Comer of fame extends Frame is even with damage to flame more it= 3/4" past curb curb. and/or top slab lace into the street (if applicable). M J Top slab has holes larger Top slab is free of than 2 square inches or holes and cracks. racks wider than 1/4" (iutend is to make sure all material is running into the basin). M J Frame not sitting flush on Frame is sitting top slab, i.e., separation of flush on top slab. more than 3/4" of the frame from the top slab. A J Cracks in basin Cracks wider than 1/2" and Basin replaced or walls/bottom longer than 3', any repaired to design evidence ofsog particles standards. Conrad entering catch basin a professional through cracks or engineer for maintenance pesonjudges evaluation. that structure is unsound. A J Cracks wider than 1/2" and No cracks more longer than ]'at disjoint of than 1/4" wide at anyinlet/ouflet pipe many thejointof evidenceofsoilpanicles idet/outle pipe. entering catch basin through cracks. KPFF Consulting Engineers 12 January 9, 2007 Forrester Heights Final Drainage Report KPFF Consulting Engineers Frequency Drainage Problem Conditions to Check For Conditions That System Should Exist Feature A Settlementlmis- Basin has settled more than Basin replaced or alignment 1" or has rotated more than repaired to design 2" out of alignment. standards. Contact a professional engineer for evaluation. M.S. Fire hazard or Presence of chemicals such No color, odor or other pollution as natural gas, oil all sludge. Basin is gasoline. Obnoxious color, dug out and clean. odor or sludge noted. M.S. Outlet pipe is Vegetation or rolls No vegetation or clogged with growing in inleVoutlet pipe not growth vegetation joints that are more than 6" present. tall and less than 6" apart. Iryou ere wwre wMibcra pmblemwere, pluc c®Ycttlw Jmiedictiw and eek fro txlmicel err®s�mce. o Kcy A>AMmnul(o— mApnl pmfm!) S=.jim^eohcdWc) =Nhr mejm rb,ma KPFF Consulting Engineers 13 January 9, 2007 I Forrester Heights Final Drainage Report KPFF Consulting Engineers ' ATTACHMENT "A" (CONTINUED) Maintenance Checklist for Infiltration Systems Frequency Drainage J Problem Conditions to Check For Conditions That Should System Exist Feature M,S Cenral Trash & See Maintenance See Maintenance debris Checklist for Ponds. Checklist for Ponds. buildup in pond M Poisonous See Maintenance See Maintenance vegetation Checklist for Ponds. Checklist for Ponds. M,S Fire hazard See Maintenance See Maintenance or pollution Checklist for Ponds. Checklist for Ponds. M Vegetation See Maintenance See Maintenance not growing Checklist for Ponds. Checklist for Ponds. or is overgrown M Rodent See Maintenance See Maintenance holes Checklist for Ponds. Checklist for Ponds. M Insects See Maintenance See Maintenance Checklist for Ponds. Checklist for Ponds. A Storage J Sediment A soil texture test Sediment is removed area buildup in indicates facility is not and/or facility is cleaned system working at its designed so that infiltration capabilities or was system works according incorrectly designed. to design. A sediment trapping area is installed to reduce sediment transport into infiltration area. A J Storage A soil texture teat Additional volume is area drains indicates facility is not added through slowly working at its designed excavation to provide (more than capabilities or was needed storage. Soil is 48 hours) incorrectly designed. aerated and rototilled to or improve drainage. overflows Contact the City for information on its requirements regarding excavation. KPFF Consulting Engineers 14 January 9, 2007 Forrester Heights Final Drainage Report KPFF Consulting Engineers II M Sediment Any sediment and debris Clean out sump to trapping filling area to 10% of design depth, area depth from sump bottom -to -bottom of outlet pipe or obstructing flow into the connector pipe. One Time Sediment Stormwater enters Add a trapping area by trapping infiltration area directly constructing a sump for area not without treatment. settling of solids. present Segregate settling area from rest of facility. Contact City for guidance. M Rock J Sediment By visual inspection Replace gravel in rock filters and debris little or no water flows filter. through filter during heavy rainstorms. S Infiltrati Infiltration Standing Water in Excavate bottom of on Failure Inspection Well After trench as necessary but Trenches 48 hours after storm or at least 3 feet. Replace Overflow during Storms with crushed rock. Check pretreatment systems for effectiveness. Check tributary area for sediment sources. ffyou are unsure whether a problem exists, please mntact the Jurisdiction and ask for technical, mat m Comments: KU A=Aunuaf (March or April Mfea d) M = Monthly (see schedWO S = After m*r storm. KPFF Consulting Engineers 15 January 9, 2007 Forester Heights Final Drainage Report KPFF Consulting Engineers ATTACHMENT "A" (CONTINUED) Maintenance Checklist for Grounds (Landscaping) Frequen Drainage J Problem Conditions to Check Conditions That Should cy System For Exist Feature M General J Weeds Weeds growing in Weeds present in less (nonpoisono more than 20%, of the than 5%of the us) landscaped area (trees landscaped area. and shrubs only). M J Safety Any presence of poison No poisonous vegetation hazard ivy or other poisonous or insect nests present in vegetation or insect landscaped area. nests. M,S J Trash or See Ponds Checklist. See Ponds Checklist. litter M,S J Erosion of Noticeable rills are Causes of erosion are Ground seen in landscaped identified and steps Surface areas. taken to slow down/spread out the water. Eroded areas are filled, contoured, and seeded. A Trees and J Damage Limbs or parts of trees Trim trees/shrubs to shrubs or shrubs that are restore shape. Replace split or broken which trees/shrubs with severe affect more than 25% damage. of the total foliage of the tree or shrub. M J Trees or shrubs that Replant tree, inspecting have been blown down for injury to stem or or knocked over. roots. Replace if severely damaged. A J Trees or shrubs, which Place stakes and rubber - are not adequately coated ties around young supported or are trees/shrubs for support. leaning over, causing exposure of the roots. Ifyou era wsure whether a problem msty please mntnot the Jurisdiction and a for technical assistance. Comments: Key A =Amvel (March or Apil preferred) M = Monthly free schedule) S-After.*r smrma KPFF Consulting Engineers 16 January 9, 2007 Forrester Heights Final Drainage Report KPFF Consulting Engineers SECTION 2 - RESPONSIBLE ORGANIZATION The project owner shall be responsible for the operations and maintenance of all onsite storm drainage facilities. SECTION 3 - VEGETATION MANAGEMENT PLAN All disturbed pervious areas on the site will be landscaped to provide an aesthetically pleasing environment. SECTION 4 - SOURCE CONTROL Warning signs (e.g., "Dump No Waste — Drains to Groundwater') will be embossed or painted on or adjacent to all storm drain inlets and will be repainted periodically as necessary. KPFF Consulting Engineers 17 January 9, 2007 Appendix I Preliminary Drainage Calculations PRELIMINARY DRAINAGE CALCULATIONS The following calculations are based on the requirements contained in the 1992 Washington State Department of Ecology (WSDOE) Stormwater Management Manual for the Puget Sound Basin. DESIGN AND BASIN INFORMATION SUMMARY: Soil Classification (Soil Survey of Thurston County, WA): SCS Soil Classification: Spanaway, Nisqually Hydrologic Group: B Design Infiltration Rate: 20 inches/hour ' SCS Runoff Curve Number: (Table 1II-1.3 WSDOE Storm Manual) Post -developed (Lawns, 75% + grass cover): CN = 80 ' Post -development (impervious) CN = 98 Post -development wet ponds CN=100 Pre -development CN = 64 ' Rainfall Design Storms: (WSDOE Isopluvial Maps- App, AIII-1.1 of WSDOE Storm Manual) 6 month storm (64% of 2 yr. storm) = 1.28" 2 year/24 hour storm = 2.0" 10 year/24 hour storm = 3.0" 100 year/24 hour storm = 4.0" Post -Development Basin Area Summary Basin A Basin B Basin C Total Driveways (500 sf per lot) 0.28 ac** 0.00ac 0.00 ac 0.28 ac Roofs Area 0.45 ac 0.37 ac 0.00 ac 0.83 ac (1,500 sf roof per lot) Impervious Roadway 1.46 ac* 0.00 ac 0.00 ac 1.46 ac* Impervious Sidewalk 0.16 ac 0.00 ac 0.00 ac 0.16 ac Undisturbed Pervious 0.00 ac 2.50 ac 1.49 ac 3.99 ac ** Includes driveways in Basin B that drain to Basin A *Includes that portion of the roadway that is constructed on parcel 21725130200 and frontage improvements along SR 507. KPFF Consulting Engineers 7e January 9, 2007 Stormwater Treatment: Basin 'A!: Per StormShed calculations 6-month storm event resulted in a peak flow rate of 0.5019 cfs, and a peak volume of 8,638 d. The DOE manual, section 11I-4.3.2, requires that "the permanent pool volume equals the runoff volume from the 6-month, 24-hour design storm." Boston Harbor software was used to calculate provided wet pond volume. The 3 foot deep "dead storage" pool with 3,609 sf of bottom area and 3:1 slopes will provide I5,630 cf of available permanent pool volume, which exceeds the required volume of 8.638 cf. Treatement Volume Provided: ' Stage Elevation Live Storage Volume Wet Pond Bottom 352.0 0 ' 353.0 4,126 cf 354.0 5,191 cf 6 mo Design Elevation 355.0 6,313 cf Total Wet Pond Dead Storage = 15,520 cf Stormwater Storage and Infiltration: Storas a Capacity Summary Impervious Area Disturbed Pervious Area Storage (1) Required Storage Provided Basin A 1.90 ac 1.93 ac 5,547 cf 15,630 cf TOTAL 1.90 ac 1.93 ac 5.547 cf 15.630 cf 1. Based on design infiltration rate of20-tuches/hour using StorneShed modeling software for the I0 ysar storm event KPFF Consulting Engineers 19 January 9, 2007 I BASIN A Event Summary ' - --- --- -- --- Event Peak Q (cfs)'Pen T (hrs) FHyd Vol (acft) Area (ac) Methot 6mo 7 0.5011 8.00 j 0.1983 3.8300 SBUH 2 year '.' 0.9322 8.00 j 0.3714 3.8300 ,; SBUH 10 year 1.6306 8.00 0.6393 3.8300 SBUH 1 100 year l 2.3799 - 8.00 0.9245 j 3.8300 SBUH Record Id. BASIN A '..Design Method '! SBUH lRainfall type TYPEIA Hyd Intv 10.00 min Peaking Factor 48 0 '...... y.� Abstraction Coeff 0.20 _ c Pervious Area (AMC 2) 1.93 ac DCIA 1.90 ac �_- ------ ,Pervious CN '..� 80 00 DC CN ! 98.00 Pervious TC 20 42 min (DC TC 7.57 min Pervious CN Cale (i Description Subk ea Sub cn Residential districts - 1/4 acre 1 93 ac 8 00 0 Pervious Composited CN (AMC 2) 80.00 Pervious TC Cale Ir Type ! Description Length ( Slope Coeff Misc I TT Shee� t -'Short prairie grass and 110.00 'lawns.: 0. 15 F 2 00% �j0.1500 -00 13.38 �i�im ,mtn Sheet Smooth Surfaces.: 0.011 250.00 IR �- 1.00% `0.0110 2 00 4.21 nvn Channel (Concrete pipe (n=0.012) 35.00 ft 0.50% 0.0120 0.19 min �hannel gym) Concrete pipe (n�.012) J 80.00 ft 1.00% �0.0120 0.31 -,min Channel Concreten 0.012 pipe( ) 90.00 ft �I j'� 0.89 /° 0.0120 �t.._ �i (0.24 min Concrete i e n-0.012) _..200.00 �109Channel 0.0120 0.75 min!(interm) -... ,:. �ICnhtmnel (Concrete pipe (n�.012) 200. 3.11%° ,I0.0120 Channel '.Concrete pipe (n-0.012) (intemi) Channel ...Concrete pipe (n=0.012) (intent) '.Channel Concrete pipe (n=0.012) '.,'.(interm) 11.57%'0.0120 00.00 111 0.14 min 0.12 min 0.11 min Channel (intern) .....,Concretepipe(n-0.012) R ' - 13.08%0.0120 0.11 min-:. Channel (Concrete pipe (n-�.012) 1I2.00 ft ---. - 2.83 /0 0.01201 0.26 min [2.83 Channel (interne) iConcrete pipe (n-0.012) 41.00 ft 1.00% 0.0120 '' -,_U.In min422 i Pervious TC r20.. min j Directly Connected CN Cale Description ( SubArea j Sub cn F rodway 1.46 ac j� 98.00 .._-.... � sidewalks -.__ 0 16 ac -- 98.00 j---- driveways r 0.28 ac '...� 98.00 DC Composited CN (AMC 2) 98.00 Directly Connected TC Cale Type Description j Length Slope Coeff Misc TT Sheet Smooth Surfaces.: 0.01117.50 ft 2.00% i0.0110 2.00 in i0.38 min Shee� t-- Smooth Surfaces.: 0.011 250.00 ft 1.00% 10.0110 2.00 in l4.21 mitt Channel (interm) Concrete pipe (n 0.012) 135.00 ft 0.50% 0.0120 0.19 min 'Channel (intern)', Concrete pipe (n-0.012) i80.00 ft 1.00% I0. 210 0 �0.31 min Channel (interne) Concrete pipe (n=0.012) (92. 00 ft 0.89% 0.0120 0.38 (Channel (intent) Concrete pipe (n-0.012) 200.00 ft 1.09% 0.0t20 �10.75 min Channel Concrete pipe (n=0Al2) 20 00 ft 3.11°10 0.0120 0.45 tnvt �.Chatme�-1(intertn). Concrete pipe (n=0.012) 100.00 R 8.38% (0. 210 0 0.14 min :Channel inert --- Concrete Wipe in 0.012 _1100.00 ft I l 570/910. 10 20 I0.12 min (Channel (intern) Concrete pipe (n-0.012) 1100.00 It 11.77% �0. 2 0.11 min Channel (intern) Concrete pipe (n 0.012) 100.00 ft 13.08%: 0.0120 +0.11�min' Hydrograph ID: BASIN A - 6 mo Area 3.8300 ac Hyd int 10.00 min ase Flow � Peak flow 0 5011 cfs Peak Time 18 001as Fyd Vol jO 1983 acft Hydrograph ID: BASIN A - 100 year Area 13.8300 ac I Hyd Int 110.00 min Base Flow l Peak flow i2.3799 cfs Peak Time I8.00 his rHyd Vol j0.9245 acft --.--- ------.... _._.ea _........_..-- _ - _.......- ft Record Id. BASIN A -- Descrip basin a increment FO f ft 1 Start El. 351.0000 ft Max El. 1356.0000ft Stage Area 1. ....Staff( Area(sf) j 351.00 2206.8600 j 3552.00 .._...--- 353.00 2817.0300 - -- --- � 3487,7300 354.00 4208.9800 355.00 F 4989.7800 35, 01 5827.1300 Stage Storage P51MOO ft 0.0000 of 351.1000 ft 223.7369 cf .351.2000 ft 453.5754 cf 351.3000 ft 689.5157 cf � 51.4000 ft 931.5576 cf Rating Curve 353,6000#7886.7881 cf S3 7000R 8282.4424 cf §5:8 8685.3086 of �OQ 19 5.3887 cf 95116797 cf ' 3351.5000 fC,1179.7013 cf RIMF9937.4824 cf 351.6000 ft',1433.9467 of - , 10370.0918 c1 351.7000 ft 1694.2937 cf 354.3000 ft..10810.5098 cf 351.8000 ft 1960.7424 cf 354.4000 ft'11258.7363 cf: 351.9000 ft 2233.2930 cf 354.5000 ft �111714.7695 cf' 352.0000 f[ 2511_9451 cf 354.6000 ft 12178.6123 cf- 352.1000 fl 2797.0015 cf 354.7000 ft 5 -_. _ ':12650.2617 cf 352.2000 f[ 3088.7651 cf 354.8000 ft 13129.7197 cf 352.3000 ft 33R7.2356 cf 3154.9000 ft )361 &9863 cf 352.4000 ft 3(i92.4131 cf 355.0000 ft,1411 6 352.5000 ft 4004.2976 cf 1355.1000 ft 1461 25 2�46 cf 352.6000 ft 4322.8892 cf 355.2000 ft.15126.7627 cf 352.7000 ft 4649.1875 cf 355.3000 ft'15646.6748 cf 352.8000 It 4980.1929 cf 355.4000 11,16174. 6600 cf !352.9000 ft 5318.9058 cf 355.5000 ftf16711.6191 cf 353.0000 fl 5664.3252 cf.355.6000 ft:'17256.6504cf 353.1000 ft 6016.7041 cf 355.700011.17810.0566 cf �53.2000 ft 6376.2959 cf 355.8000 ft 18371.8359 cf 653.3000 ft'6743.1001 cf i355.900011 18941.9883 cf 353.4000 ft 7117.1172 cf'356.0000 1AF19520.5156 cf Record Id. BASIN A RLP Descrip: Prototype Record Increment 0.10 ft ' Start El. 1351.0000 ft Maxa- 356.0000 ft N Storage Node BASIN A Discharge Node BAS Record Id., BASIN A ' jDescrip: basin a lncrement 0.10 ft ,Start El. 351.0000 ft f Max El. 356.0000 ft Stage Area 351.00 r 2206 8600 352.00 2817 0300 [953.00 3487.7300 ' 354.00 4208.9800 355.00 4989.7800 __.. _356.00 5827.130— 0 J Record Id: BASIN A Descrip:.stage discharge Increment 10. ! -.Start El. 351.0000 ft !Max El. 1356.0000ft Stage (ft) Discharge (cfs) F— 351.00 ! 0.6944 352.00 —'�� 0.6944 353.00 0.6944 354.00 0.6944 355.00 0.6944 356.00 i0.6944 LPOOLCOMPUTE [BASIN A RLP] SUMMARY using Puls Start of live storage: 351.0000 ft F Event Match Q (cfs) Peak Q (cfs) Peak Stg (ft) Vol (ct) Vol (acft) Time to Empty, 100 year 2.3799 0,6944 352.9639 5539.46 0 1272 26.67 109 year Hydrograph Plot - egsmtq t(loyea# st LL 0 r ^ m � ^ ,�l1 lm•1 O � O W N,N 1m'I 0� N Im•I O 0 �D ,III O N (V M < V VI lO A 0 OI OI O N fV A s f - - - - ' - '- IV N fV (mV (V IPV N N Time in Hours Appendix II Preliminary Drainage and TESC Plan Appendix III Facility Summary Form THURSTON REGION ' FACILITY SUMMARY FORM Complete one (1) for each facility (detentiontretention, coalescing plate 91ter, etc.) on the project site. Attach 8 1/2 x 11 sketch showing location of facility. Proponent's Facility Name or Identifier le.g., Pond A) : See Part 6 Name of Road or Street to Access Facility.: SR-507 Hearings Examiner Case Number- ' Development Rev. Project No.Bldg Permit No.: Parcel Number. 21725130300 To be completed by Utility Stab: Utility Facility Number Project Number (m m) Parcel Number Status: (num, lch) 0, Known; 1, Public; 2 Unknown; 3, Unassigned Basin and Subbasin: (mum, 6ch) (2ch for basin, 2ch for subbasin, 2eb future Respomiblejunsdiction: (alpha, lcb) Part 1 - Purest Name and Pr000�nt Project Name: Forrester Heights Project Owner: FHI LLC Project Contact: Dan Lee Address: 4200 60, Avenue SE Suite 301 Lacey WA 98503 Phone: (360) 923-9655 Project Proponent: Address: Same (if different) Same Phone: Same Project Engineer: Firm: KPFEConvulting e. mk et g, P F Engineers Phone: f360)292-7930 Part 2 - Project Lpeation Section 25 Township 17N Range If Part 3 - Type of Pert Application Type of permit (e.g., Commercial Bldg): Building Other Permits (circle) ❑DOF/W HPA ❑COE 404 ❑COE Wetlands []DOE Dam Safety ❑FEMA ❑Floodplain ❑Shoreline Mgmt [:[Rockery/Retaining Wall []Encroachment ®Grading ❑NPDES ❑Other Plumbing, Electrical, Utiliiy Other Agencies (Federal, State, Local, etc.) that have had or will review this Drainage Erosion Control Plan: N/A What stream basin is this project in (e.g. Percival, Woodland): Thompson Creek Project Size, acres L0.92 total Zoning.R-4 Onsite: Residential Subdivision: Number oflots: Lot size (average), acres: Building PermalCommercial Plat: Buildmg(s) Foolprini, acres Concrete Paving, acres: Gravel Surface, acres: Lattice Block Paving acres: Public Roads (including gravel shoulder), acres: Yes 24 0.20 ac Private Roads (including sidewalks), acres: Onsite Impervious Surface Total, acres: 1.90 Part 5 - I mDevelooed Project Site Characteristics Stream through site, y/n: Name: DNR Type: Type of feature tiffs facility discharges to (Le., lake, stream, intemrittent stream, pothole, roadside ditch, sheettlow to adjacent private property, etc.): Infiltration into ground Swales, Ravines, y/n: Steep slopes, (steeper than /5%) y/n: Erosion hazard, y/n: 100 yr Floodplain, y/n: Lakes or Wetlands, y/n: Seeps/Springs, y/n: High Groundwater Table, y/n: Wellhead Protection or Aquifer Sensitive Area, y/n: Part 6 - Facility Description— Wet Pond Al Total Area Tributary to Facility Including Of%site (acres): Total Onstte Area Tributary to Facility (acres): Design Impervious Area Tributary to Facility (acres): Design Landscaped Area Tributary to Facility (acres): Design Total Tributary Area to Facility (acres): Enter a one (1) for the type offwdity: Wet pond detention Wet pond water surface area, acres Drypond detention Underground detention No Yes No No No No No Yes REA 1.91 1.90 118 2.99 1 0.17 Infiltration pond Dry well infiltration Coalescing plate separator Centrifuge separator Other Outlet type (Enter a one (1) for each type present) Filter Oil water separator Single orifice Multiple orifices Weir Spillway P—P(s) Other Part 7 - Release to Groundwater Design percolation Rate to Groundwater (if applicable) Part 6 - Facilitv Description —Infiltration PondA1 Total Area Tributary to Facility Including OJjsite (acres): Total Onsue Area Tributary to Facility (acres): Design Impervious Area Tributary to Facility (acres): Design Landscaped Area Tributary to Facility (acres): Design Total Tributary Area to Facility (acres): Enter a one (I) for the type offaciliry: Wetpond detention Wet pond water surface area, acres Dry pond detention Undergroundaetenitton Infiltration pond Dry well infiltration Coalescing plate separator 1 I N/A 2.99 2.91 1.90 1.18 2.99 rI Centrifuge separator Other: Outlet type (Enter a one (I)jar each ON Present) Filter Oil water separator Single orifice Multiple orifices Weir SPZIIWW P—P(s) Other-lnfidowhon Part 7 - Release to Groundwater Design Percolation Rate to Groundmier (if applicable) J I 20 inches/houv Appendix IV FEMA Firm Map PROGRAM FIRM FLOOD INSURANCE RATE MAP CITY OF YELM, WASI ON (THURSCON COUNTY) P IIIIIAIIIIIIIIII IIIlillllllllllll ONLY PANEL PRINTED COMMUNITY -PANEL NUMBER 530310 0001 A nar EFFECTIVE DATE: j DUNE 16, 1999 WLNII Federal Emergency Management Agency I IF ,lus�. 11 Appendix V Vicinity Map M -g • MOF WAy P%Ud zz M7. : 541 317 8713 Jul. 31 2002 04: 27PM P2 s s T Nd sow, N o a OMENW r To 2V 1 EMTMG at -LL i -- MW NW.L wows mss .s I EXOTMD W r E U3T 86P W TAA ' EXOTMka DRAM FG= 4Mf SCAM -I" -2W SSIC l NWIb AVOMC, Suite 2 Bod OR7II11i Phmc 541.83MO RAX Saw.m X-% JVZa- s HWYi SE Yebk WA 9 SI' IPLM 2Vi=r302-W 1,4 ti 1 air, --o C ,e,# THURMN GEODATA CENTER SUMMARY TABLE GRACIELA HOFFMAN FAMILY TRUST, MAILING ADDRESS: PO BOX 246 RIVERTON, UT 84065 SITE ADDRESS: 15036 SE 507 HWY YELM, WA 98597 PARCEL#: 21725130200 SECTION: 25171E WETLAND: NONE PRIORITY SPECIES: NO WITHIN FLOODZONE: NO HIGH GW FLOOD HAZARD: NO SALMON CREEK BASIN: NO WITHIN FLOOD OF 1996: NO STREAM: NONE GREEN COVE BASIN ZONING: NO ZONING: RR1/5 ZONING: R_4 SHORELINE DESIGNATION: NONE MAPPED LANDSLIDE HAZARDS: UNKNOWN HAZARDOUS SLOPES: YES HYDRIC SOILS: NO JURISDICTION: YELM JURISDICTION: YELM2ANNEX WITHIN A WATER SERVICE AREA: UNKNOWN WELLHEAD PROTECTION AREA: UNKNOWN SANITARIAN: 1 PLANNING SUB AREA: 9G SCHOOL DISTRICT: YELM FIRE DISTRICT: 2 YELM PLANNER: 3 CONTAMINATION SITE: NO NITRATES: NO OAK STANDS: YES CRITICAL BUFFERS: NO LONG TERM AGRICULTURE BUFFER: NO MINERAL LANDS BUFFER: NO LONG TERM FORESTRY BUFFER: NO HOTSPOT AREA: NO THURSTON COUNTY Not to Scale Wed Aug 1411:31:42 2002 All Locafims am Appo:dkretc. 'I mdm This nnp is to be used as an illushafim only. All data teptsuftdnycl—e with= nofice! 11 1 1 MINI N I N I m li mm 11 MINE MIN MAIN!MIN iN NNNEM NINE M N NONE liir l MIN! MIN ON Now CS 1[!'Ni' .,"i IINN'N MIN' MIN NI/ Ili NNIN%iN 17N NN MIN N E Ri/.MIN MIN MIN l! %N N NN IN Ail'I 1 Al1 1ME No N ii N1 t':N:/NIA/i.,.1R N AERNFIcI1:!_EWnRENI BEAMA w ifflumommom h wry CMUNIMIN MEN a 3 kv e t_ N N e w w t p1 f F,y R t. O Y e s i j a i i VOqT-31-2006 TUE 10:40 AM FAX NO. P. 02 WELL CONSTRUCTION/DECOMMISSIONING INSPECTION APPLICATION o PART 1: APPLICANTIPARCEL IDENTIFICATION D TAX PARCEL #21725130200 START CARD AE01997 LIST PENDING COUNTY BUILDING OR SUBDIVISION APPLICATIONS: OWNER: FH1 LLC TELEPHONE NUMBER. 360.446.3083 OWNER MAILING ADDRESS: 4200 6t" Ave. S.E. #301, Lacey, WA 98503 DRILLING SITE ADDRESS: 15036 S.E. 507 Hwy., Yelm, WA DRILLING FIRM NAME: ARCADIA DRILLING INC. TELEPHONE# 360.426.3395 DATE OF ANTICIPATED INITIATION OF WORK: 11/3/2006 A~ 3 Sj c~ SIGNATURE OF LEGAL OWNER: Signature of owner constitutes permission to enter the property for inspection of the well. Note: A well site Inspection Is required prior to drilling if the well Is Intended to provide water for anything other than a single domestic use for a single family home. PART 2: DEPARTMENTAL USE ONLY n date: 10IW- Phone date: Re: Letter date: Re: l,zll. - s hS . ;OS~SEF~p~'~it~T~1S;IhID SEi Ji D S 1XI IT1= Drilling equipment dean Drilling water from potable 2' annular space maintained Well properly capped Starter casing - minimum 18 feet Condition of casing acceptable Well sitinglaccess satisfactory Dentonite available at sit Tagging satisfactory Surface s present Artesian w pecial standards scading water, waste/leakage Comments: l03 t* . 1 om - k7~ V-J~vJ 4- Driller licensed 1GYes -N Drill rig on site Vies No Owner on site _Yes _.No Evidence form attached _Yes _No Variance required _Yes _No Photographs taken -Yes _No (number) Water Rights needed ^Y No Witness statement attached _Yes _No (number) Inspected by Inspection date: l( Lc •r^ . \13- \ lib ~-3~l