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Viewmont Place Preliminary Storm Report Civil Engineers ● Structural Engineers ● Landscape Architects ● Community Planners ● Land Surveyors Preliminary Stormwater Report PREPARED FOR: Copper Ridge LLC PO Box 73790 Puyallup, WA 98373-0790 PROJECT: Viewmont Place Yelm, Washington 2230396.10 PREPARED BY: Ryan Inouye, PE Project Engineer REVIEWED BY: Scott T. Kaul, PE, LEED AP Associate Principal DATE: November 2024 Preliminary Stormwater Report PREPARED FOR: Copper Ridge LLC PO Box 73790 Puyallup, WA 98373-0790 PROJECT: Viewmont Place Yelm, Washington 2230396.10 PREPARED BY: Ryan Inouye, PE Project Engineer REVIEWED BY: Scott T. Kaul, PE, LEED AP Associate Principal DATE: November 2024 I hereby state that this Preliminary Stormwater Report for Viewmont Place 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. 11/22/2024 Preliminary Stormwater Report Viewmont Place 2230396.10 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 ..................................................................................... 1 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 – Operation and Maintenance ................................................................................... 2 3.0 Existing Conditions ....................................................................................................................... 2 4.0 Soils Reports .................................................................................................................................. 2 5.0 Wells and Septic Systems ............................................................................................................. 2 6.0 Fuel Tanks ...................................................................................................................................... 3 7.0 Sub-Basin Description................................................................................................................... 3 8.0 Analysis of the 100-Year Flood ..................................................................................................... 3 9.0 Facility Sizing and Downstream Analysis ................................................................................... 3 9.1 Conveyance ........................................................................................................................ 3 9.2 Runoff Treatment ................................................................................................................ 3 9.3 Flow Control ........................................................................................................................ 4 9.4 On-lot Infiltration - Roof Runoff ........................................................................................... 4 10.0 Covenants Dedications, Easements ............................................................................................ 4 11.0 Property Owners Association Articles of Incorporation ............................................................ 4 12.0 Conclusion ...................................................................................................................................... 5 Preliminary Stormwater Report Viewmont Place 2230396.10 Appendices Appendix A General Exhibits A-1 ............. Vicinity Map A-2 ............. Developed Conditions A-3 ............. NRCS Soil Map A-4 ............. FEMA 100-Year Flood Plain Map Appendix B Stormwater B-1 ............. Basin Map B-2 ............. WWHM Report Appendix C Geotechnical Report TO BE PROVIDED Preliminary Stormwater Report Viewmont Place 1 2230396.10 1.0 Project Overview The following hydrology report summarizes the storm drainage analysis and design for the Viewmont Place Plat, a 115-lot development located between Mountain View Road SE and Killion Road SE. The project includes the addition of 115 residential lots for single-family homes, roadways and sidewalks, sewer, water services, and stormwater facilities. The proposed roadway and utilities will extend from both Mountain View Road SE and Killion Road SE. Refer to Appendix A-2 for the developed conditions. A 10’ ROW dedication along Mountain View Road is provided to construct sidewalks along the frontage. The project covers City of Yelm tax parcels 21724120100 and 21724120200 in Thurston County. The 19.27-acre site is located in Section 24, Township 17 North, Range 1 East, W.M. Refer to Appendix A-1 for the vicinity map. 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 (SMMWW). 2.0 Summary of Minimum Requirements This project is a new development that will add more than 5,000 square feet of new plus replaced hard surfaces; therefore, all Minimum Requirements (MR) apply to the 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 will be prepared under separate cover for final design. 2.3 MR 3 – Source Control of Pollution Pollution source control will be provided for the site by separating roof runoff from pollution generating surfaces. The residential roads should be maintained and cleaned of debris, garbage, and sediment, as required. The Construction SWPPP, to be submitted under separate cover, will provide details on the control of pollution during construction. 2.4 MR 4 – Preservation of Natural Drainage Systems and Outfalls The project proposes to retain all stormwater onsite by infiltrating all stormwater runoff. There are no natural drainage systems or outfalls leaving the site to preserve. 2.5 MR 5 – Onsite Stormwater Control This project will meet the LID performance standard. The LID Performance Standard will be met by infiltrating all stormwater runoff from the site. Preliminary Stormwater Report Viewmont Place 2 2230396.10 2.6 MR 6 – Runoff Treatment Over 5,000 square feet of pollution generating hard surfaces (PGIS) are proposed; therefore, runoff treatment is required for this site. Basic treatment is required. Stormwater from the roadways will be conveyed to stormwater treatment filters before being infiltrated. Two basins are proposed to convey stormwater to separate treatment systems and infiltration trenches. The treatment systems are sized using the water quality output of the Western Washington Hydrology Model (WWHM 2012) to meet the SMMWW treatment requirement of at least 91 percent of runoff volume. Refer to Section 9.0 for facility sizing. 2.7 MR 7 – Flow Control Over 10,000 square feet of new effective impervious surfaces are proposed; therefore, flow control is required for the site. Proposed flow control is achieved by infiltrating all stormwater from the site into native soils. A combination of on-lot systems and regional facilities are proposed to infiltrate stormwater. By infiltrating stormwater from the hard surfaces, all surfaces onsite are considered ineffective impervious. Refer to Section 9.0 for facility sizing. 2.8 MR 8 – Wetlands Protection To our knowledge, there are no wetlands on or adjacent to the site. 2.9 MR 9 – Operation and Maintenance The City of Yelm shall be responsible for the operation and maintenance of the stormwater facilities. Operation and maintenance for drainage facilities constructed for each lot shall be the responsibility of the individual lot owners. An Operation and Maintenance Plan for the private stormwater facilities will be prepared under separate cover for final design. 3.0 Existing Conditions The site is primarily pasture with a previously removed single family residence in the southwest corner. The site generally slopes toward the north property line, with the low point near the center of the site. Existing topography throughout the site has slopes ranging from 0 to 5 percent. 4.0 Soils Reports Site soils are identified by the Natural Resources Conservation Service (NRCS) Soil Survey as Spanaway gravelly sandy loam and Spanaway stony sandy loam. Spanaway soils are in the hydrologic soil group Type A/B. Refer to Appendix A-3. At the time of this report field exploration is being conducted by the geotechnical engineer to evaluate soils. Preliminary design assumptions use the adjacent soils report from the plat north of the project (The Hutch). Soils for the adjacent plat were determined to be well draining and a long term design infiltration rate of 14.5-inches per hour was recommended. 5.0 Wells and Septic Systems One well near the north property line was previously decommissioned in 2006. The decommissioned well is identified on the existing conditions map of the civil engineering plans. An abandoned septic system from the previously demolished house may still be onsite in the southwest corner of the property. If found during construction the septic system is to be removed per all applicable health department requirements. Preliminary Stormwater Report Viewmont Place 3 2230396.10 An existing septic system is on the adjacent property at the southwest corner of the plat. All onsite infiltration systems will provide minimum separation to the adjacent septic system. 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. 6.0 Fuel Tanks There are no known fuel tanks at the project site. 7.0 Sub-Basin Description Two separate basins are proposed for the regional systems at the northwest and southeast corners of the project. Each basin has an independent treatment and infiltration system. Impervious surfaces for the basins include all driveways, roadways, and sidewalks. A small portion of the frontages at the points of connection will drain to the site and be mitigated with the project. See Appendix B-1 for the Basin Map. Roof drainage from several lots near the southeast corner of the plat will be conveyed to the regional system. These lots are conveyed to the regional system because of the proximity to the adjacent septic system. The rest of the lots will provide on-lot infiltration systems to mitigate roof runoff. There is no significant source of run-on to the project. Adjacent properties are at approximately similar elevations. 8.0 Analysis of the 100-Year Flood Federal Emergency Management Agency (FEMA) mapping does not indicate flooding in the immediate area. See Appendix A-4 for FEMA flood mapping. 9.0 Facility Sizing and Downstream Analysis 9.1 Conveyance Conveyance sizing will be provided with final engineering. 9.2 Runoff Treatment BayFilters cartridges will treat stormwater runoff to meet the basic treatment requirement. Water quality rates are determined from Western Washington Hydrology Model (WWHM); refer to Appendix B-2. Basin A provides a stormwater treatment vault with an internal bypass weir; the offline treatment flow is met. Basins B-1 and B-2 provide separate stormwater treatment manholes; the online treatment flows are met. A summary of the treatment requirements and the provided treatments are summarized in the table below. Preliminary Stormwater Report Viewmont Place 4 2230396.10 Table 1 - Treatment Summary Basin Online Treatment Flow (cfs) Offline Treatment Flow (cfs) Proposed Filters Treatment Provided (cfs) A 0.7024 0.4093 5 x Bayfilter Cartridges (model 545) 0.501 B-1 0.1015 0.0576 2 x Bayfilter Cartridges (model 545) 0.201 B-2 0.1193 0.0678 2 x Bayfilter Cartridges (model 545) 0.201 Treatment flow is based on the WWHM 15-mlnute time step. 9.3 Flow Control Infiltration galleries are proposed to infiltrate all stormwater from the site to meet flow control and LID performance standard requirements. Two separate infiltration galleries are proposed. The infiltration system’s area is sized to infiltrate the entire runoff directed to each; refer to Appendix B-2. A summary of the minimum design requirements and the provided systems are summarized in the table below. Table 2 – Flow Control/Infiltration Summary Facility Design Infiltration Rate (in/hr) Minimum Facility Footprint (sf) Proposed Facility Footprint (sf) Percent Infiltrated A 14.5 6,724 6,755 100 B 14.5 2,070 2,100 100 9.4 On-lot Infiltration - Roof Runoff On-lot downspout infiltration systems BMP T5.10A are proposed for each single-family home. The individual infiltration trenches or drywells will be sized in accordance with the SMMWW Volume V – Chapter 4 – BMP T5.10A Downspout Full Infiltration. Sizing to be provided with future building permits. 10.0 Covenants Dedications, Easements A 10-foot utility easement is proposed along the front of each lot. A 10-foot utility easement is proposed along the rear of lots abutting Mountain View Rd SE and Killion St SE. A 10-foot ROW dedication is proposed along the west side of the property. The storm facilities within the private tracts shall be privately owned and maintained. A maintenance agreement should be executed to ensure future maintenance of the facilities. The on-lot systems will be privately owned and maintained and therefore do not require covenants, dedications, or easements. 11.0 Property Owners Association Articles of Incorporation Associated Articles of Incorporation will be developed and recorded in conjunction with the final plat to provide for maintenance of open space, park tracts, and the maintenance of the private components of the stormwater management facilities. A maintenance agreement with schedules of required maintenance will be prepared for this project and incorporated into the Property Owners’ Association Articles of Incorporation. Preliminary Stormwater Report Viewmont Place 5 2230396.10 12.0 Conclusion The proposed project involves site improvements associated with a 115-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 (SMMWW). This report and associated plans have been prepared within the guidelines established by the 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. Ryan Inouye, PE Project Engineer RI/jms November 2024 \\ahbl.com\data\Projects\2023\2230396\WORDPROC\Reports\20241122 Rpt (Prelim Storm) 2230396.10.docx Preliminary Stormwater Report Viewmont Place 2230396.10 Appendix A General Exhibits A-1 .................... Vicinity Map A-2 .................... Developed Conditions A-3 .................... NRCS Soil Map A-4 .................... FEMA 100-Year Flood Plain Map Civil Engineers Structural Engineers Landscape Architects Community Planners Land Surveyors Neighbors VIEWMONT PLACE 2230396.10 Q:\2023\2230396\10_CIV\CAD\EXHIBITS\Vicinity Map.dwg VICINITY MAP NOT TO SCALE N SITE 510TAHOMA BLVD SE KILLION ST SE BERRY VALLEY RD SE 91ST AVE SE MTN. VIEW RD SE 93RD AVE SE NW CULLENS RD s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s ss s s s s s s s s s s s s s ss s s s s s s s 13 12 43 42 83 79 89 87 86 74 78 73 71 75 91 92 93 94 96 99 102 90 95TRACT D 97 98 101 100 39 40 41 44 TRACT C 2930 28 110 109 108 52515049484746 2 1 4 106 103 104 114 112 111 115 105 113 107 37 36 35 34 33 32 31 60 45 88 TR A C T A 72 70 69 76 80 81 82 6567 68 64 61 63 66 TRACT E 18 10 25 17 9 24 16 23 15 22 14 21 27 20 26 19 11 5 6 7 8 85 84 77 TRACT G55535458565759 62 TRACT F TRACT B ROW 38 KI L L I O N S T S E MO U N T A I N V I E W R D S E ROAD A ROAD C ROAD F ROAD I RO A D B RO A D E RO A D H RO A D D RO A D G 10.00' ROW DEDICATION 3 2215 North 30th Street, Suite 300, Tacoma, WA 98403 253.383.2422 TEL 253.383.2572 FAX JOB NO. DATE: VIEWMONT PLACE DEVELOPED CONDITIONS A-2 2230396.10 11/21/2024 N GRAPHIC SCALE 0 50 100 1" = 50 FEET 25 Q:\2023\2230396\10_CIV\CAD\EXHIBITS\Developed Conditions.dwg STORMWATER FILTER MANHOLE INFILTRATION GALLERY STORMWATER FILTER MANHOLE INFILTRATION GALLERY STORMWATER FILTER VAULT Soil Map—Thurston County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/20/2024 Page 1 of 3 51 9 9 6 4 0 51 9 9 7 1 0 51 9 9 7 8 0 51 9 9 8 5 0 51 9 9 9 2 0 51 9 9 9 9 0 52 0 0 0 6 0 51 9 9 6 4 0 51 9 9 7 1 0 51 9 9 7 8 0 51 9 9 8 5 0 51 9 9 9 2 0 51 9 9 9 9 0 52 0 0 0 6 0 528620 528690 528760 528830 528900 528970 529040 529110 529180 529250 528620 528690 528760 528830 528900 528970 529040 529110 529180 529250 46° 57' 12'' N 12 2 ° 3 7 ' 2 7 ' ' W 46° 57' 12'' N 12 2 ° 3 6 ' 5 5 ' ' W 46° 56' 58'' N 12 2 ° 3 7 ' 2 7 ' ' W 46° 56' 58'' N 12 2 ° 3 6 ' 5 5 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 150 300 600 900 Feet 0 45 90 180 270 Meters Map Scale: 1:3,100 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. APPROXIMATE PROJECT LIMITS 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 18, Aug 27, 2024 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 11/20/2024 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 110 Spanaway gravelly sandy loam, 0 to 3 percent slopes 39.8 92.8% 112 Spanaway stony sandy loam, 0 to 3 percent slopes 3.1 7.2% Totals for Area of Interest 42.9 100.0% Soil Map—Thurston County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/20/2024 Page 3 of 3 Map Unit Description (Brief, Generated) The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions in this report, along with the maps, provide information on the composition of map units and properties of their components. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. The Map Unit Description (Brief, Generated) report displays a generated description of the major soils that occur in a map unit. Descriptions of non-soil (miscellaneous areas) and minor map unit components are not included. This description is generated from the underlying soil attribute data. Additional information about the map units described in this report is available in other Soil Data Mart reports, which give properties of the soils and the limitations, capabilities, and potentials for many uses. Also, the narratives that accompany the Soil Data Mart reports define some of the properties included in the map unit descriptions. Report—Map Unit Description (Brief, Generated) Thurston County Area, Washington Map Unit: 110—Spanaway gravelly sandy loam, 0 to 3 percent slopes Component: Spanaway (100%) The Spanaway component makes up 100 percent of the map unit. Slopes are 0 to 3 percent. The parent material consists of volcanic ash over gravelly outwash. Depth to a root restrictive layer is greater than 60 inches. The natural drainage class is somewhat excessively drained. Water movement in the most restrictive layer is high. Available water to a depth of 60 inches (or restricted depth) is low. Shrink-swell potential is low. This soil is not flooded. It is not ponded. There is no zone of water saturation within a depth of 72 inches. Organic matter content in the surface horizon is about 10 percent. This component is in the R002XA006WA Puget Lowlands Prairie ecological site. Nonirrigated land capability classification is 3s. Irrigated land capability classification is 3s. This soil does not meet hydric criteria. Map Unit Description (Brief, Generated)---Thurston County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/20/2024 Page 1 of 2 Map Unit: 112—Spanaway stony sandy loam, 0 to 3 percent slopes Component: Spanaway (100%) The Spanaway component makes up 100 percent of the map unit. Slopes are 0 to 3 percent. The parent material consists of volcanic ash over gravelly outwash. Depth to a root restrictive layer is greater than 60 inches. The natural drainage class is somewhat excessively drained. Water movement in the most restrictive layer is high. Available water to a depth of 60 inches (or restricted depth) is low. Shrink-swell potential is low. This soil is not flooded. It is not ponded. There is no zone of water saturation within a depth of 72 inches. Organic matter content in the surface horizon is about 10 percent. This component is in the R002XA006WA Puget Lowlands Prairie ecological site. Nonirrigated land capability classification is 4s. This soil does not meet hydric criteria. Data Source Information Soil Survey Area: Thurston County Area, Washington Survey Area Data: Version 18, Aug 27, 2024 Map Unit Description (Brief, Generated)---Thurston County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/20/2024 Page 2 of 2 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 Depth Zone 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 mile Zone X Future Conditions 1% Annual Chance Flood Hazard Zone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to Levee Zone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood Hazard Zone 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 11/20/2024 at 9:36 PM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location. 1:6,000 122°37'29"W 46°57'18"N 122°36'51"W 46°56'53"N Basemap Imagery Source: USGS National Map 2023 APPROXIMATE PROJECT LIMITS Preliminary Stormwater Report Viewmont Place 2230396.10 Appendix B Stormwater B-1 .................... Basin Map B-2 .................... WWHM Report 88 TRACT A 72 70 69 76 80 45 85 84 77 TRACT G55535458565759 62 TRACT F TRACT B 81 82 83 79 89 87 86 74 78 73 71 75 91 92 93 94 96 99 102 90 95 TRACT D 97 98 101 100 39 40 41 44 TRACT C 2930 28 110 109 108 52515049484746 2 1 3 4 106 103 104 114 112 111 115 105 113 107 37 36 35 34 33 32 31 60 65 67 68 64 61 63 66 TRACT E 18 10 25 17 9 24 16 23 15 22 14 21 27 20 26 19 11 5 6 7 8 ROW 38 13 12 43 42 347 347 3 4 8 3 4 8 34 5 34 2 34 3 34 4 34 6 3 4 7 341 341 34 2 3 4 2 342 342 342 343 344 34 3 34 4 345 3 4 5 34 4 3 4 4 34 0 3 4 0 3 4 1 34 1 342 342 34 1 34 2 3 4 3 34 4 34 0 34 1 34 2 34 3 340 340 341 342 341 344 344 344 345 345 344 344 346 347 348 34 5 34 4 34 6 34 7 340 340 341 341 34 0 34 1 342 342 342 341 342 342 342 3 4 3 344 3 4 3 343 3 4 4 34 3 34 3 343 343 344 344 3 4 1 34 2 34 5 34 3 34 4 34 6 347 34 8 34 9 340 338 339 341 342 344 34 2 34 2 34 3 34 3 34 3 34 4 344 3 4 4 34 4 34 5 3 4 4 34 6 34 6 34 7 347 34 7 34 8 34 9 3 4 8 347 348 2215 North 30th Street, Suite 300, Tacoma, WA 98403 253.383.2422 TEL 253.383.2572 FAX JOB NO. DATE: VIEWMONT BASIN MAP B-1 2230396.10 11/21/2024 BASIN AREAS BASIN A BASIN B-1 BASIN B-2 LAWN 2.35 AC 0.60 AC 0.48 AC ROAD 2.61 AC 0.23 AC 0.48 AC ROOF -0.14 AC - DRIVEWAY 1.57 AC 0.12 AC 0.21 AC SIDEWALK 0.47 AC 0.16 AC 0.08 AC TOTAL 7.00 AC 1.24 AC 1.26 ACBASIN A BASIN B-2 INFILTRATION SYSTEM A INFILTRATION SYSTEM B BASIN B-1 Q:\2023\2230396\10_CIV\CAD\EXHIBITS\Prelim Basin Map.dwg STORMWATER FILTER A STORMWATER FILTER B-2 STORMWATER FILTER B-1 WWHM4 PROJECT REPORT Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 2 General Model Information WWHM2012 Project Name:Prelim Trench Sizing Site Name:Viewmont Site Address: City: Report Date:11/21/2024 Gage:Eaton Creek Data Start:1955/10/01 Data End:2011/09/30 Timestep:15 Minute Precip Scale:0.857 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 Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 3 Landuse Basin Data Predeveloped Land Use Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 4 Mitigated Land Use Basin A Bypass:No GroundWater:No Pervious Land Use acre A B, Lawn, Flat 2.35 Pervious Total 2.35 Impervious Land Use acre ROADS FLAT 2.61 DRIVEWAYS FLAT 1.57 SIDEWALKS FLAT 0.47 Impervious Total 4.65 Basin Total 7 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Gravel Trench A Gravel Trench APOC 1POC 1 Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 5 Basin B-1 Bypass:No GroundWater:No Pervious Land Use acre A B, Lawn, Flat 1.24 Pervious Total 1.24 Impervious Land Use acre ROADS FLAT 0.23 ROOF TOPS FLAT 0.14 DRIVEWAYS FLAT 0.12 SIDEWALKS FLAT 0.16 Impervious Total 0.65 Basin Total 1.89 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Gravel Trench B Gravel Trench BPOC 2POC 2 Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 6 Basin B-2 Bypass:No GroundWater:No Pervious Land Use acre A B, Lawn, Flat 0.48 Pervious Total 0.48 Impervious Land Use acre ROADS FLAT 0.48 DRIVEWAYS FLAT 0.21 SIDEWALKS FLAT 0.08 Impervious Total 0.77 Basin Total 1.25 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Gravel Trench B Gravel Trench BPOC 3POC 3 Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 7 Routing Elements Predeveloped Routing Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 8 Mitigated Routing Gravel Trench A Bottom Length:82.00 ft. Bottom Width:82.00 ft. Trench bottom slope 1:0 To 1 Trench Left side slope 0:0 To 1 Trench right side slope 2:0 To 1 Material thickness of first layer:1 Pour Space of material for first layer:0.3 Material thickness of second layer:1 Pour Space of material for second layer:0.3 Material thickness of third layer:1 Pour Space of material for third layer:0.3 Infiltration On Infiltration rate:14.5 Infiltration safety factor:1 Total Volume Infiltrated (ac-ft.):727.543 Total Volume Through Riser (ac-ft.):0 Total Volume Through Facility (ac-ft.):727.543 Percent Infiltrated:100 Total Precip Applied to Facility:0 Total Evap From Facility:0 Discharge Structure Riser Height:3 ft. Riser Diameter:10 in. Element Outlets: Outlet 1 Outlet 2 Outlet Flows To: Gravel Trench Bed Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.154 0.000 0.000 0.000 0.0333 0.154 0.001 0.000 2.256 0.0667 0.154 0.003 0.000 2.256 0.1000 0.154 0.004 0.000 2.256 0.1333 0.154 0.006 0.000 2.256 0.1667 0.154 0.007 0.000 2.256 0.2000 0.154 0.009 0.000 2.256 0.2333 0.154 0.010 0.000 2.256 0.2667 0.154 0.012 0.000 2.256 0.3000 0.154 0.013 0.000 2.256 0.3333 0.154 0.015 0.000 2.256 0.3667 0.154 0.017 0.000 2.256 0.4000 0.154 0.018 0.000 2.256 0.4333 0.154 0.020 0.000 2.256 0.4667 0.154 0.021 0.000 2.256 0.5000 0.154 0.023 0.000 2.256 0.5333 0.154 0.024 0.000 2.256 0.5667 0.154 0.026 0.000 2.256 0.6000 0.154 0.027 0.000 2.256 0.6333 0.154 0.029 0.000 2.256 0.6667 0.154 0.030 0.000 2.256 0.7000 0.154 0.032 0.000 2.256 0.7333 0.154 0.034 0.000 2.256 MEETS FLOW CONTROL BY INFILTRATING FULL RUNOFF FILE 6,724 SF FOOTPRINT 3' TRENCH HEIGHT Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 9 0.7667 0.154 0.035 0.000 2.256 0.8000 0.154 0.037 0.000 2.256 0.8333 0.154 0.038 0.000 2.256 0.8667 0.154 0.040 0.000 2.256 0.9000 0.154 0.041 0.000 2.256 0.9333 0.154 0.043 0.000 2.256 0.9667 0.154 0.044 0.000 2.256 1.0000 0.154 0.046 0.000 2.256 1.0333 0.154 0.047 0.000 2.256 1.0667 0.154 0.049 0.000 2.256 1.1000 0.154 0.050 0.000 2.256 1.1333 0.154 0.052 0.000 2.256 1.1667 0.154 0.054 0.000 2.256 1.2000 0.154 0.055 0.000 2.256 1.2333 0.154 0.057 0.000 2.256 1.2667 0.154 0.058 0.000 2.256 1.3000 0.154 0.060 0.000 2.256 1.3333 0.154 0.061 0.000 2.256 1.3667 0.154 0.063 0.000 2.256 1.4000 0.154 0.064 0.000 2.256 1.4333 0.154 0.066 0.000 2.256 1.4667 0.154 0.067 0.000 2.256 1.5000 0.154 0.069 0.000 2.256 1.5333 0.154 0.071 0.000 2.256 1.5667 0.154 0.072 0.000 2.256 1.6000 0.154 0.074 0.000 2.256 1.6333 0.154 0.075 0.000 2.256 1.6667 0.154 0.077 0.000 2.256 1.7000 0.154 0.078 0.000 2.256 1.7333 0.154 0.080 0.000 2.256 1.7667 0.154 0.081 0.000 2.256 1.8000 0.154 0.083 0.000 2.256 1.8333 0.154 0.084 0.000 2.256 1.8667 0.154 0.086 0.000 2.256 1.9000 0.154 0.088 0.000 2.256 1.9333 0.154 0.089 0.000 2.256 1.9667 0.154 0.091 0.000 2.256 2.0000 0.154 0.092 0.000 2.256 2.0333 0.154 0.094 0.000 2.256 2.0667 0.154 0.095 0.000 2.256 2.1000 0.154 0.097 0.000 2.256 2.1333 0.154 0.098 0.000 2.256 2.1667 0.154 0.100 0.000 2.256 2.2000 0.154 0.101 0.000 2.256 2.2333 0.154 0.103 0.000 2.256 2.2667 0.154 0.105 0.000 2.256 2.3000 0.154 0.106 0.000 2.256 2.3333 0.154 0.108 0.000 2.256 2.3667 0.154 0.109 0.000 2.256 2.4000 0.154 0.111 0.000 2.256 2.4333 0.154 0.112 0.000 2.256 2.4667 0.154 0.114 0.000 2.256 2.5000 0.154 0.115 0.000 2.256 2.5333 0.154 0.117 0.000 2.256 2.5667 0.154 0.118 0.000 2.256 2.6000 0.154 0.120 0.000 2.256 2.6333 0.154 0.121 0.000 2.256 2.6667 0.154 0.123 0.000 2.256 Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 10 2.7000 0.154 0.125 0.000 2.256 2.7333 0.154 0.126 0.000 2.256 2.7667 0.154 0.128 0.000 2.256 2.8000 0.154 0.129 0.000 2.256 2.8333 0.154 0.131 0.000 2.256 2.8667 0.154 0.132 0.000 2.256 2.9000 0.154 0.134 0.000 2.256 2.9333 0.154 0.135 0.000 2.256 2.9667 0.154 0.137 0.000 2.256 3.0000 0.154 0.138 0.000 2.256 Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 11 Gravel Trench B Bottom Length:46.00 ft. Bottom Width:45.00 ft. Trench bottom slope 1:0 To 1 Trench Left side slope 0:0 To 1 Trench right side slope 2:0 To 1 Material thickness of first layer:1 Pour Space of material for first layer:0.3 Material thickness of second layer:1 Pour Space of material for second layer:0.3 Material thickness of third layer:1 Pour Space of material for third layer:0.3 Infiltration On Infiltration rate:14.5 Infiltration safety factor:1 Total Volume Infiltrated (ac-ft.):222.233 Total Volume Through Riser (ac-ft.):0 Total Volume Through Facility (ac-ft.):222.233 Percent Infiltrated:100 Total Precip Applied to Facility:0 Total Evap From Facility:0 Discharge Structure Riser Height:3 ft. Riser Diameter:10 in. Element Outlets: Outlet 1 Outlet 2 Outlet Flows To: Gravel Trench Bed Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.047 0.000 0.000 0.000 0.0333 0.047 0.000 0.000 0.694 0.0667 0.047 0.001 0.000 0.694 0.1000 0.047 0.001 0.000 0.694 0.1333 0.047 0.001 0.000 0.694 0.1667 0.047 0.002 0.000 0.694 0.2000 0.047 0.002 0.000 0.694 0.2333 0.047 0.003 0.000 0.694 0.2667 0.047 0.003 0.000 0.694 0.3000 0.047 0.004 0.000 0.694 0.3333 0.047 0.004 0.000 0.694 0.3667 0.047 0.005 0.000 0.694 0.4000 0.047 0.005 0.000 0.694 0.4333 0.047 0.006 0.000 0.694 0.4667 0.047 0.006 0.000 0.694 0.5000 0.047 0.007 0.000 0.694 0.5333 0.047 0.007 0.000 0.694 0.5667 0.047 0.008 0.000 0.694 0.6000 0.047 0.008 0.000 0.694 0.6333 0.047 0.009 0.000 0.694 0.6667 0.047 0.009 0.000 0.694 0.7000 0.047 0.010 0.000 0.694 0.7333 0.047 0.010 0.000 0.694 0.7667 0.047 0.010 0.000 0.694 0.8000 0.047 0.011 0.000 0.694 MEETS FLOW CONTROL BY INFILTRATING FULL RUNOFF FILE 2,070 SF FOOTPRINT 3' TRENCH HEIGHT Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 12 0.8333 0.047 0.011 0.000 0.694 0.8667 0.047 0.012 0.000 0.694 0.9000 0.047 0.012 0.000 0.694 0.9333 0.047 0.013 0.000 0.694 0.9667 0.047 0.013 0.000 0.694 1.0000 0.047 0.014 0.000 0.694 1.0333 0.047 0.014 0.000 0.694 1.0667 0.047 0.015 0.000 0.694 1.1000 0.047 0.015 0.000 0.694 1.1333 0.047 0.016 0.000 0.694 1.1667 0.047 0.016 0.000 0.694 1.2000 0.047 0.017 0.000 0.694 1.2333 0.047 0.017 0.000 0.694 1.2667 0.047 0.018 0.000 0.694 1.3000 0.047 0.018 0.000 0.694 1.3333 0.047 0.019 0.000 0.694 1.3667 0.047 0.019 0.000 0.694 1.4000 0.047 0.020 0.000 0.694 1.4333 0.047 0.020 0.000 0.694 1.4667 0.047 0.020 0.000 0.694 1.5000 0.047 0.021 0.000 0.694 1.5333 0.047 0.021 0.000 0.694 1.5667 0.047 0.022 0.000 0.694 1.6000 0.047 0.022 0.000 0.694 1.6333 0.047 0.023 0.000 0.694 1.6667 0.047 0.023 0.000 0.694 1.7000 0.047 0.024 0.000 0.694 1.7333 0.047 0.024 0.000 0.694 1.7667 0.047 0.025 0.000 0.694 1.8000 0.047 0.025 0.000 0.694 1.8333 0.047 0.026 0.000 0.694 1.8667 0.047 0.026 0.000 0.694 1.9000 0.047 0.027 0.000 0.694 1.9333 0.047 0.027 0.000 0.694 1.9667 0.047 0.028 0.000 0.694 2.0000 0.047 0.028 0.000 0.694 2.0333 0.047 0.029 0.000 0.694 2.0667 0.047 0.029 0.000 0.694 2.1000 0.047 0.029 0.000 0.694 2.1333 0.047 0.030 0.000 0.694 2.1667 0.047 0.030 0.000 0.694 2.2000 0.047 0.031 0.000 0.694 2.2333 0.047 0.031 0.000 0.694 2.2667 0.047 0.032 0.000 0.694 2.3000 0.047 0.032 0.000 0.694 2.3333 0.047 0.033 0.000 0.694 2.3667 0.047 0.033 0.000 0.694 2.4000 0.047 0.034 0.000 0.694 2.4333 0.047 0.034 0.000 0.694 2.4667 0.047 0.035 0.000 0.694 2.5000 0.047 0.035 0.000 0.694 2.5333 0.047 0.036 0.000 0.694 2.5667 0.047 0.036 0.000 0.694 2.6000 0.047 0.037 0.000 0.694 2.6333 0.047 0.037 0.000 0.694 2.6667 0.047 0.038 0.000 0.694 2.7000 0.047 0.038 0.000 0.694 2.7333 0.047 0.039 0.000 0.694 Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 13 2.7667 0.047 0.039 0.000 0.694 2.8000 0.047 0.039 0.000 0.694 2.8333 0.047 0.040 0.000 0.694 2.8667 0.047 0.040 0.000 0.694 2.9000 0.047 0.041 0.000 0.694 2.9333 0.047 0.041 0.000 0.694 2.9667 0.047 0.042 0.000 0.694 3.0000 0.047 0.042 0.000 0.694 Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 14 Analysis Results POC 1 POC #1 was not reported because POC must exist in both scenarios and both scenarios must have been run. BASIN A Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 15 POC 2 POC #2 was not reported because POC must exist in both scenarios and both scenarios must have been run. BASIN B-1 Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 16 POC 3 POC #3 was not reported because POC must exist in both scenarios and both scenarios must have been run. BASIN B-2 Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 17 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. Prelim Trench Sizing 11/21/2024 9:23:15 AM Page 18 Appendix Predeveloped Schematic Prelim Trench Sizing 11/21/2024 9:23:17 AM Page 19 Mitigated Schematic Prelim Trench Sizing 11/21/2024 9:23:19 AM Page 20 Predeveloped UCI File Prelim Trench Sizing 11/21/2024 9:23:19 AM Page 21 Mitigated UCI File RUN GLOBAL WWHM4 model simulation START 1955 10 01 END 2011 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 Prelim Trench Sizing.wdm MESSU 25 MitPrelim Trench Sizing.MES 27 MitPrelim Trench Sizing.L61 28 MitPrelim Trench Sizing.L62 30 POCPrelim Trench Sizing1.dat 31 POCPrelim Trench Sizing2.dat 32 POCPrelim Trench Sizing3.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 7 IMPLND 1 IMPLND 5 IMPLND 8 IMPLND 4 RCHRES 1 RCHRES 2 COPY 501 COPY 502 COPY 503 DISPLY 1 DISPLY 2 DISPLY 3 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin A MAX 1 2 30 9 2 Basin B-1 MAX 1 2 31 9 3 Basin B-2 MAX 1 2 32 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 502 1 1 503 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** Prelim Trench Sizing 11/21/2024 9:23:19 AM Page 22 7 A/B, Lawn, Flat 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 7 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 7 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 7 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 7 0 5 0.8 400 0.05 0.3 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 7 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 7 0.1 0.5 0.25 0 0.7 0.25 END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 7 0 0 0 0 3 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 1 ROADS/FLAT 1 1 1 27 0 5 DRIVEWAYS/FLAT 1 1 1 27 0 8 SIDEWALKS/FLAT 1 1 1 27 0 4 ROOF TOPS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 5 0 0 1 0 0 0 8 0 0 1 0 0 0 4 0 0 1 0 0 0 END ACTIVITY PRINT-INFO Prelim Trench Sizing 11/21/2024 9:23:19 AM Page 23 <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 4 1 9 5 0 0 4 0 0 0 1 9 8 0 0 4 0 0 0 1 9 4 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 5 0 0 0 0 0 8 0 0 0 0 0 4 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 5 400 0.01 0.1 0.1 8 400 0.01 0.1 0.1 4 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 5 0 0 8 0 0 4 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 5 0 0 8 0 0 4 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin A*** PERLND 7 2.35 RCHRES 1 2 PERLND 7 2.35 RCHRES 1 3 IMPLND 1 2.61 RCHRES 1 5 IMPLND 5 1.57 RCHRES 1 5 IMPLND 8 0.47 RCHRES 1 5 Basin B-1*** PERLND 7 1.24 RCHRES 2 2 PERLND 7 1.24 RCHRES 2 3 IMPLND 1 0.23 RCHRES 2 5 IMPLND 4 0.14 RCHRES 2 5 IMPLND 5 0.12 RCHRES 2 5 IMPLND 8 0.16 RCHRES 2 5 Basin B-2*** PERLND 7 0.48 RCHRES 2 2 PERLND 7 0.48 RCHRES 2 3 IMPLND 1 0.48 RCHRES 2 5 IMPLND 5 0.21 RCHRES 2 5 IMPLND 8 0.08 RCHRES 2 5 Basin A*** PERLND 7 2.35 COPY 501 12 Prelim Trench Sizing 11/21/2024 9:23:19 AM Page 24 PERLND 7 2.35 COPY 501 13 IMPLND 1 2.61 COPY 501 15 IMPLND 5 1.57 COPY 501 15 IMPLND 8 0.47 COPY 501 15 Basin B-1*** PERLND 7 1.24 COPY 502 12 PERLND 7 1.24 COPY 502 13 IMPLND 1 0.23 COPY 502 15 IMPLND 4 0.14 COPY 502 15 IMPLND 5 0.12 COPY 502 15 IMPLND 8 0.16 COPY 502 15 Basin B-2*** PERLND 7 0.48 COPY 503 12 PERLND 7 0.48 COPY 503 13 IMPLND 1 0.48 COPY 503 15 IMPLND 5 0.21 COPY 503 15 IMPLND 8 0.08 COPY 503 15 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 COPY 502 OUTPUT MEAN 1 1 48.4 DISPLY 2 INPUT TIMSER 1 COPY 503 OUTPUT MEAN 1 1 48.4 DISPLY 3 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** 1 Gravel Trench A 2 1 1 1 28 0 1 2 Gravel Trench B 2 1 1 1 28 0 1 END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 2 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 2 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** 1 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 2 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** Prelim Trench Sizing 11/21/2024 9:23:19 AM Page 25 1 1 0.02 0.0 0.0 0.5 0.0 2 2 0.01 0.0 0.0 0.5 0.0 END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> 1 0 4.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2 0 4.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES FTABLE 1 92 5 Depth Area Volume Outflow1 Outflow2 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.154362 0.000000 0.000000 0.000000 0.033333 0.154362 0.001544 0.000000 2.256898 0.066667 0.154362 0.003087 0.000000 2.256898 0.100000 0.154362 0.004631 0.000000 2.256898 0.133333 0.154362 0.006174 0.000000 2.256898 0.166667 0.154362 0.007718 0.000000 2.256898 0.200000 0.154362 0.009262 0.000000 2.256898 0.233333 0.154362 0.010805 0.000000 2.256898 0.266667 0.154362 0.012349 0.000000 2.256898 0.300000 0.154362 0.013893 0.000000 2.256898 0.333333 0.154362 0.015436 0.000000 2.256898 0.366667 0.154362 0.016980 0.000000 2.256898 0.400000 0.154362 0.018523 0.000000 2.256898 0.433333 0.154362 0.020067 0.000000 2.256898 0.466667 0.154362 0.021611 0.000000 2.256898 0.500000 0.154362 0.023154 0.000000 2.256898 0.533333 0.154362 0.024698 0.000000 2.256898 0.566667 0.154362 0.026242 0.000000 2.256898 0.600000 0.154362 0.027785 0.000000 2.256898 0.633333 0.154362 0.029329 0.000000 2.256898 0.666667 0.154362 0.030872 0.000000 2.256898 0.700000 0.154362 0.032416 0.000000 2.256898 0.733333 0.154362 0.033960 0.000000 2.256898 0.766667 0.154362 0.035503 0.000000 2.256898 0.800000 0.154362 0.037047 0.000000 2.256898 0.833333 0.154362 0.038590 0.000000 2.256898 0.866667 0.154362 0.040134 0.000000 2.256898 0.900000 0.154362 0.041678 0.000000 2.256898 0.933333 0.154362 0.043221 0.000000 2.256898 0.966667 0.154362 0.044765 0.000000 2.256898 1.000000 0.154362 0.046309 0.000000 2.256898 1.033333 0.154362 0.047852 0.000000 2.256898 1.066667 0.154362 0.049396 0.000000 2.256898 1.100000 0.154362 0.050939 0.000000 2.256898 1.133333 0.154362 0.052483 0.000000 2.256898 1.166667 0.154362 0.054027 0.000000 2.256898 1.200000 0.154362 0.055570 0.000000 2.256898 1.233333 0.154362 0.057114 0.000000 2.256898 1.266667 0.154362 0.058657 0.000000 2.256898 1.300000 0.154362 0.060201 0.000000 2.256898 1.333333 0.154362 0.061745 0.000000 2.256898 1.366667 0.154362 0.063288 0.000000 2.256898 1.400000 0.154362 0.064832 0.000000 2.256898 1.433333 0.154362 0.066376 0.000000 2.256898 1.466667 0.154362 0.067919 0.000000 2.256898 1.500000 0.154362 0.069463 0.000000 2.256898 1.533333 0.154362 0.071006 0.000000 2.256898 1.566667 0.154362 0.072550 0.000000 2.256898 1.600000 0.154362 0.074094 0.000000 2.256898 1.633333 0.154362 0.075637 0.000000 2.256898 Prelim Trench Sizing 11/21/2024 9:23:19 AM Page 26 1.666667 0.154362 0.077181 0.000000 2.256898 1.700000 0.154362 0.078725 0.000000 2.256898 1.733333 0.154362 0.080268 0.000000 2.256898 1.766667 0.154362 0.081812 0.000000 2.256898 1.800000 0.154362 0.083355 0.000000 2.256898 1.833333 0.154362 0.084899 0.000000 2.256898 1.866667 0.154362 0.086443 0.000000 2.256898 1.900000 0.154362 0.087986 0.000000 2.256898 1.933333 0.154362 0.089530 0.000000 2.256898 1.966667 0.154362 0.091073 0.000000 2.256898 2.000000 0.154362 0.092617 0.000000 2.256898 2.033333 0.154362 0.094161 0.000000 2.256898 2.066667 0.154362 0.095704 0.000000 2.256898 2.100000 0.154362 0.097248 0.000000 2.256898 2.133333 0.154362 0.098792 0.000000 2.256898 2.166667 0.154362 0.100335 0.000000 2.256898 2.200000 0.154362 0.101879 0.000000 2.256898 2.233333 0.154362 0.103422 0.000000 2.256898 2.266667 0.154362 0.104966 0.000000 2.256898 2.300000 0.154362 0.106510 0.000000 2.256898 2.333333 0.154362 0.108053 0.000000 2.256898 2.366667 0.154362 0.109597 0.000000 2.256898 2.400000 0.154362 0.111140 0.000000 2.256898 2.433333 0.154362 0.112684 0.000000 2.256898 2.466667 0.154362 0.114228 0.000000 2.256898 2.500000 0.154362 0.115771 0.000000 2.256898 2.533333 0.154362 0.117315 0.000000 2.256898 2.566667 0.154362 0.118859 0.000000 2.256898 2.600000 0.154362 0.120402 0.000000 2.256898 2.633333 0.154362 0.121946 0.000000 2.256898 2.666667 0.154362 0.123489 0.000000 2.256898 2.700000 0.154362 0.125033 0.000000 2.256898 2.733333 0.154362 0.126577 0.000000 2.256898 2.766667 0.154362 0.128120 0.000000 2.256898 2.800000 0.154362 0.129664 0.000000 2.256898 2.833333 0.154362 0.131208 0.000000 2.256898 2.866667 0.154362 0.132751 0.000000 2.256898 2.900000 0.154362 0.134295 0.000000 2.256898 2.933333 0.154362 0.135838 0.000000 2.256898 2.966667 0.154362 0.137382 0.000000 2.256898 3.000000 0.154362 0.138926 0.000000 2.256898 3.033333 0.154362 0.144071 0.053769 2.256898 END FTABLE 1 FTABLE 2 92 5 Depth Area Volume Outflow1 Outflow2 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.047521 0.000000 0.000000 0.000000 0.033333 0.047521 0.000475 0.000000 0.694792 0.066667 0.047521 0.000950 0.000000 0.694792 0.100000 0.047521 0.001426 0.000000 0.694792 0.133333 0.047521 0.001901 0.000000 0.694792 0.166667 0.047521 0.002376 0.000000 0.694792 0.200000 0.047521 0.002851 0.000000 0.694792 0.233333 0.047521 0.003326 0.000000 0.694792 0.266667 0.047521 0.003802 0.000000 0.694792 0.300000 0.047521 0.004277 0.000000 0.694792 0.333333 0.047521 0.004752 0.000000 0.694792 0.366667 0.047521 0.005227 0.000000 0.694792 0.400000 0.047521 0.005702 0.000000 0.694792 0.433333 0.047521 0.006178 0.000000 0.694792 0.466667 0.047521 0.006653 0.000000 0.694792 0.500000 0.047521 0.007128 0.000000 0.694792 0.533333 0.047521 0.007603 0.000000 0.694792 0.566667 0.047521 0.008079 0.000000 0.694792 0.600000 0.047521 0.008554 0.000000 0.694792 0.633333 0.047521 0.009029 0.000000 0.694792 0.666667 0.047521 0.009504 0.000000 0.694792 0.700000 0.047521 0.009979 0.000000 0.694792 0.733333 0.047521 0.010455 0.000000 0.694792 Prelim Trench Sizing 11/21/2024 9:23:19 AM Page 27 0.766667 0.047521 0.010930 0.000000 0.694792 0.800000 0.047521 0.011405 0.000000 0.694792 0.833333 0.047521 0.011880 0.000000 0.694792 0.866667 0.047521 0.012355 0.000000 0.694792 0.900000 0.047521 0.012831 0.000000 0.694792 0.933333 0.047521 0.013306 0.000000 0.694792 0.966667 0.047521 0.013781 0.000000 0.694792 1.000000 0.047521 0.014256 0.000000 0.694792 1.033333 0.047521 0.014731 0.000000 0.694792 1.066667 0.047521 0.015207 0.000000 0.694792 1.100000 0.047521 0.015682 0.000000 0.694792 1.133333 0.047521 0.016157 0.000000 0.694792 1.166667 0.047521 0.016632 0.000000 0.694792 1.200000 0.047521 0.017107 0.000000 0.694792 1.233333 0.047521 0.017583 0.000000 0.694792 1.266667 0.047521 0.018058 0.000000 0.694792 1.300000 0.047521 0.018533 0.000000 0.694792 1.333333 0.047521 0.019008 0.000000 0.694792 1.366667 0.047521 0.019483 0.000000 0.694792 1.400000 0.047521 0.019959 0.000000 0.694792 1.433333 0.047521 0.020434 0.000000 0.694792 1.466667 0.047521 0.020909 0.000000 0.694792 1.500000 0.047521 0.021384 0.000000 0.694792 1.533333 0.047521 0.021860 0.000000 0.694792 1.566667 0.047521 0.022335 0.000000 0.694792 1.600000 0.047521 0.022810 0.000000 0.694792 1.633333 0.047521 0.023285 0.000000 0.694792 1.666667 0.047521 0.023760 0.000000 0.694792 1.700000 0.047521 0.024236 0.000000 0.694792 1.733333 0.047521 0.024711 0.000000 0.694792 1.766667 0.047521 0.025186 0.000000 0.694792 1.800000 0.047521 0.025661 0.000000 0.694792 1.833333 0.047521 0.026136 0.000000 0.694792 1.866667 0.047521 0.026612 0.000000 0.694792 1.900000 0.047521 0.027087 0.000000 0.694792 1.933333 0.047521 0.027562 0.000000 0.694792 1.966667 0.047521 0.028037 0.000000 0.694792 2.000000 0.047521 0.028512 0.000000 0.694792 2.033333 0.047521 0.028988 0.000000 0.694792 2.066667 0.047521 0.029463 0.000000 0.694792 2.100000 0.047521 0.029938 0.000000 0.694792 2.133333 0.047521 0.030413 0.000000 0.694792 2.166667 0.047521 0.030888 0.000000 0.694792 2.200000 0.047521 0.031364 0.000000 0.694792 2.233333 0.047521 0.031839 0.000000 0.694792 2.266667 0.047521 0.032314 0.000000 0.694792 2.300000 0.047521 0.032789 0.000000 0.694792 2.333333 0.047521 0.033264 0.000000 0.694792 2.366667 0.047521 0.033740 0.000000 0.694792 2.400000 0.047521 0.034215 0.000000 0.694792 2.433333 0.047521 0.034690 0.000000 0.694792 2.466667 0.047521 0.035165 0.000000 0.694792 2.500000 0.047521 0.035640 0.000000 0.694792 2.533333 0.047521 0.036116 0.000000 0.694792 2.566667 0.047521 0.036591 0.000000 0.694792 2.600000 0.047521 0.037066 0.000000 0.694792 2.633333 0.047521 0.037541 0.000000 0.694792 2.666667 0.047521 0.038017 0.000000 0.694792 2.700000 0.047521 0.038492 0.000000 0.694792 2.733333 0.047521 0.038967 0.000000 0.694792 2.766667 0.047521 0.039442 0.000000 0.694792 2.800000 0.047521 0.039917 0.000000 0.694792 2.833333 0.047521 0.040393 0.000000 0.694792 2.866667 0.047521 0.040868 0.000000 0.694792 2.900000 0.047521 0.041343 0.000000 0.694792 2.933333 0.047521 0.041818 0.000000 0.694792 2.966667 0.047521 0.042293 0.000000 0.694792 3.000000 0.047521 0.042769 0.000000 0.694792 3.033333 0.047521 0.044353 0.053769 0.694792 END FTABLE 2 Prelim Trench Sizing 11/21/2024 9:23:19 AM Page 28 END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 0.857 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 0.857 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL COPY 2 OUTPUT MEAN 1 1 48.4 WDM 702 FLOW ENGL REPL COPY 502 OUTPUT MEAN 1 1 48.4 WDM 802 FLOW ENGL REPL COPY 3 OUTPUT MEAN 1 1 48.4 WDM 703 FLOW ENGL REPL COPY 503 OUTPUT MEAN 1 1 48.4 WDM 803 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 2 PERLND PWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 2 MASS-LINK 3 PERLND PWATER IFWO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 3 MASS-LINK 5 IMPLND IWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 5 MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 END MASS-LINK END RUN Prelim Trench Sizing 11/21/2024 9:23:19 AM Page 29 Predeveloped HSPF Message File Prelim Trench Sizing 11/21/2024 9:23:19 AM Page 30 Mitigated HSPF Message File Prelim Trench Sizing 11/21/2024 9:23:19 AM Page 31 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. 2005-2024; 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 Preliminary Stormwater Report Viewmont Place 2230396.10 Appendix C Geotechnical Report TO BE PROVIDED