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2024.11.01_CK Yelm Ave & Killion_Drainage Report_FinalProject: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Technical Information Report November 2024 Page i STORMWATER TECHNICAL INFORMATION REPORT FOR Circle K W Yelm Avenue & Killion Road SE Yelm, WA 98597 October 2024 Property ID: 21724130100 Applicant Name: Circle K Stores Inc. Applicant Address: 1130 W Warner Road, Tempe, AZ 85284 Contact: Ryan Mojahed Contact Telephone: (480) 881-2320 Contact Email: rmojahed@circlek.com Civil Engineer: Liz Willmot, P.E. Project Engineer Address: 1201 3rd Ave Suite 2800, Seattle, WA 98101 Project Engineer Telephone: (206) 677-8610 Project Engineer Email: liz.willmot@kimley-horn.com 11/01/2024 Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Technical Information Report November 2024 Page ii PREPARED FOR: CITY OF YELM, WA 106 2ND STREET SE YELM, WA 98597 PREPARED BY: KIMLEY-HORN AND ASSOCIATES, INC. 1201 3RD AVE SUITE 2800 SEATTLE, WA 98101 Disclosure Statement: This document, together with the concepts and designs presented herein, as an instrument of service, is intended only for the specific purpose and client for which it was prepared. Reuse of and improper reliance on this document without written authorization and adaptation by Kimley-Horn and Associates, Inc. shall be without liability to Kimley-Horn and Associates, Inc. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Technical Information Report November 2024 Page iii Table of Contents SECTION A - PROJECT OVERVIEW ...................................................................................................... 1 A.1 SITE LOCATION AND DESCRIPTION .......................................................................................... 1 A.2 EXISTING SITE CONDITIONS ...................................................................................................... 2 A.3 PROPOSED SITE DESIGN ........................................................................................................... 3 A.4 DOWNSTREAM ANALYSIS .......................................................................................................... 4 SECTION B - MINIMUM REQUIREMENTS ............................................................................................. 5 Minimum Requirement 1: Preparation of Stormwater Site Plans ........................................................ 5 Minimum Requirement 2: Construction Stormwater Pollution Prevention Plan (SWPPP) ................... 6 Minimum Requirement 3: Source Control of Pollution........................................................................ 6 Minimum Requirement 4: Preservation of Natural Drainage Systems and Outfalls............................. 6 Minimum Requirement 5: On-Site Stormwater Management ............................................................. 6 Minimum Requirement 6: Runoff Treatment ...................................................................................... 6 Minimum Requirement 7: Flow Control ............................................................................................. 6 Minimum Requirement 8: Wetlands Protection .................................................................................. 6 Minimum Requirement 9: Operations and Maintenance .................................................................... 6 SECTION C - PRELIMINARY SOILS EVALUATION ................................................................................ 7 SECTION D - SOURCE CONTROL ......................................................................................................... 7 SECTION E - ON-SITE STORMWATER MANAGEMENT BMPs.............................................................. 7 SECTION F - RUNOFF TREATMENT ANALYSIS AND DESIGN ............................................................. 7 SECTION G - FLOW CONTROL ANALYSIS AND DESIGN ..................................................................... 8 SECTION H - WETLANDS PROTECTION............................................................................................... 8 SECTION I - OTHER PERMITS............................................................................................................... 8 SECTION J - CONVEYANCE SYSTEMS ANALYSIS AND DESIGN ........................................................ 8 SECTION K - SPECIAL REPORTS AND STUDIES ................................................................................. 8 SECTION L - OPERATIONS AND MAINTENANCE MANUAL ................................................................. 9 Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Technical Information Report November 2024 Page iv Appendices APPENDIX A: MAPS AND PHOTOS ATTACHMENT NO. 1 – VICINITY MAP ATTACHMENT NO. 2 – EXISTING CONDITIONS MAP ATTACHMENT NO. 3 – PROPOSED CONDITIONS MAP ATTACHMENT NO. 4 – SOILS MAP ATTACHMENT NO. 5 – FEMA FLOOD INSURANCE RATE MAP (FIRM) ATTACHMENT NO. 6 -- DOWNSTREAM ANALYSIS PHOTOS APPENDIX B: SITE PLAN, UTILITY PLAN, AND GRADING & DRAINAGE PLAN APPENDIX C: SPECIAL REPORTS & STUDIES APPENDIX D: FLOW CONTROL AND WATER QUALITY CALCULATIONS APPENDIX E: CONVEYANCE CALCULATIONS APPENDIX F: GEOTECHNICAL REPORT APPENDIX G: SWPPP APPENDIX H: OPERATIONS AND MAINTENANCE (O&M) MANUAL Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Page 1 SECTION A - PROJECT OVERVIEW A.1 SITE LOCATION AND DESCRIPTION The proposed project consists of a Circle K convenience store and fueling station situated on approximately 2.26 acres located in Yelm, WA. The property is currently vacant land with dense tree growth bound by Yelm Avenue W to the southwest, Killion Road SE to the southeast, vacant land to the northwest, and a retirement community and shared access road to the north. The project is located within Section 24, Township 17, Range 1E Quarter SW NE N of SR510. The project proposes improvements within parcel 21724130100 at 9548 Killion Rd SE Yelm, WA 98597, which has a commercial (C1) zoning designation. See Figure 1. Vicinity Map for proposed project location. The proposed project consists of demolition of existing on-site trees and construction of a new 5,200 SF convenience store, fueling stations with canopy and underground storage tanks, standard surface parking, trash enclosure, and associated grading, utility, and stormwater infrastructure. The project will cause an increase in impervious cover when compared to existing conditions and will therefore generate additional stormwater runoff that will be captured and conveyed to on-site water quality facilities. After project completion, existing drainage patterns, point of discharge, and stormwater storage volume will match historical conditions. The purpose of this technical information report is to provide an explanation of the site improvements and to demonstrate how the project will meet stormwater requirements. Figure 1. Vicinity Map Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Page 2 A.2 EXISTING SITE CONDITIONS The existing site consists of a vacant lot with mature trees, shrubs, grasses, and dilapidated fencing. Existing utility easements along Yelm Avenue and the southern corner contain existing underground and above ground electrical utilities. There is no known stormwater infrastructure on-site. The current stormwater runoff is either infiltrating onsite or flowing to the existing storm structures within the private drive, Killion Road SE, or Yelm Avenue. The grades on site are generally flat with slopes ranging from 1% to 3%. The existing site is made up of five threshold discharge areas (TDAs) as shown in Figure 2 below and in Appendix A. Generally, there are no conveyance features currently on-site, runoff flows across the site as sheet flow. Runoff from TDA 1 collects at a low point in the northwest corner of the site and infiltrates into the soils. If TDA 1 overflows, the runoff would sheet flow to the existing catch basins in Yelm Avenue. The catch basins in Yelm Avenue run downstream to the northwest approximately 500 feet to Contech manholes. All runoff from TDA 2 surface flows into the northern private roadway catch basins that collect in an underground storm structure on the north property. The runoff from TDA 3 remains on-site and surface flows to a low point and infiltrates. If TDA 3 were to overflow, the runoff would sheet flow into Yelm Avenue catch basins that follow the same path as TDA 1. Runoff from TDA 4 sheet flows towards Yelm Avenue and collect in the catch basins. Runoff leaves the project site to the east from TDA 5 as sheet flow into Killion Road SE and collects in the catch basins near the intersection of Yelm Avenue and Killion Road SE. These catch basins flow to Stormwater Treatment Solutions storm manholes on the east side of Killion Road SE. The site is in the Yelm Sub-basin of the Nisqually Watershed and within the critical aquifer recharge area. The Yelm Sub-basin generally flows to Yelm Creek and ultimately discharges into the Nisqually River or infiltrates into native soils to recharge the local aquifers. The existing site captures all runoff from TDA 1 and TDA 3 that generally infiltrates within the site. Runoff from TDA 2, TDA 4, and TDA 5 flow to infiltrating Contech and Stormwater Treatment Solutions storm manholes in Killion Road SE and Yelm Avenue. The existing site is located within the area of minimal flood hazard Zone X (Outside of the 500 year) per FEMA map 53067C0353F dated October 19, 2023 in Appendix A. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Page 3 Figure 2. Existing Conditions Map Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Page 4 A.3 PROPOSED SITE DESIGN The proposed site will consist of one 5,200 SF convenience store, one single stack fueling station with seven pumps (five standard pumps and two diesel pumps – one at each end cap) with a canopy, parking, landscaping, and associated infrastructure. Bioretention and Best Management Practice (BMP) devices are proposed to meet water quality requirements. Stormwater around the fuel station will be collected and treated through an oil/water separator before discharging to the southern proposed bioretention basin. Stormwater collected from the roof is proposed to discharge to grade and sheet flow directly into the northwest bioretention basin via proposed swale. The remainder of the site grades will be proposed to drain towards two bioretention basins for infiltration. The proposed site is shown below in Figure 3 and in Appendices A and B. Figure 3. Proposed Conditions Map A.4 DOWNSTREAM ANALYSIS The downstream analysis was performed using a combination of desktop investigation and a site visit performed by Kimley-Horn on December 21, 2023. Refer to Attachment No. 6 in Appendix A for the downstream analysis photos. Runoff generally remains on-site at a low point and infiltrates into the soils. In an overflow event, runoff would leave TDA 1 by sheet flow into the catch basins along Yelm Avenue. The catch basins flow downstream approximately 500 feet to the northwest and end at Contech storm manholes. At the time of the site visit, the catch basins contained minimal leaves and natural debris, and had very little to no standing water. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Page 5 TDA 2 sheet flows to the northern private drive catch basins. The existing catch basins were covered and contained natural debris with high standing water. From an underground utility map provided by the City of Yelm, the catch basins in the private drive flow to an underground detention facility on the property to the north. Runoff generally remains on-site at a low point and infiltrates into existing soils for TDA 3. In an overflow event, runoff would sheet flow into catch basins along Yelm Avenue that convey stormwater to Contech Storm manholes approximately 500 feet to the northwest. At the time of the site visit, the catch basins contained minimal leaves and natural debris and had very little to no standing water. TDA 4 sheet flows to catch basins in Yelm Avenue that convey stormwater to the northwest approximately 500’ and end at Contech Storm manholes. At the time of the site visit, the catch basins contained minimal leaves and natural debris and had very little to no standing water. TDA 5 sheet flows into Killion Road SE to catch basins near the intersection of Yelm Avenue and Killion Road SE. The stormwater is conveyed in underground pipes to Stormwater Treatment Solutions storm manholes on the eastern sidewalk of Killion Road SE across from the site. At the time of the site visit, the catch basins contained minimal leaves and natural debris and had very little to no standing water. SECTION B - MINIMUM REQUIREMENTS Activity for this project includes grading, paving, construction of vertical structures and associated utilities, stormwater infiltration basins, and lawn and landscaping plantings. This project is located within the City of Yelm, which has adopted the 2024 Department of Ecology (DOE) Stormwater Management Manual for Western Washington (SWMMWW) for stormwater requirements. All nine minimum requirements will apply to all new hard surfaces and converted pervious surfaces because the project results in more than 5,000 square feet of new hard surface. The table below summarizes the land disturbing activity. Table 1: Land Disturbance Summary AREA EXISTING PROPOSED DELTA POLLUTION GENERATING HARD SURFACE 0 AC 1.07 AC +1.07 AC NON-POLLUTION GENERATING HARD SURFACE 0 AC 0.218 AC +0.218 AC HARD SURFACE TOTAL 0 AC 1.29 AC +1.29 AC PERVIOUS SURFACE 2.28 AC 0.989 AC -1.29 AC TOTAL (HARD AND PERVIOUS):2.28 AC 2.28 AC +/- 0.00 AC Minimum Requirement 1: Preparation of Stormwater Site Plans There are no exemptions to this requirement. Stormwater Management Site Plans will be prepared as part of the construction and permitting documents and submitted for review by City of Yelm. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Page 6 Minimum Requirement 2: Construction Stormwater Pollution Prevention Plan (SWPPP) There are no exemptions to this requirement. As noted in SMMWW 1-3.4.2 MR2, projects which result in 2,000 square feet or more of new plus replaced hard surface area, or which disturb 7,000 square feet or more of land must prepare and submit a Construction Stormwater Pollution Prevention Plan (SWPPP) as part of the Final Stormwater Plan. Refer to Appendix G for the SWPPP. Minimum Requirement 3: Source Control of Pollution The proposed site improvements include a fueling station. All proposed waste generated by fueling station will be discharged to a proposed oil/water interceptor before discharging to the proposed southern bioretention basin. Refer to Appendix G for the landscaping and general maintenance BMPs discussed in the SWPPP. Minimum Requirement 4: Preservation of Natural Drainage Systems and Outfalls There are no exemptions to this requirement. Stormwater runoff from the site generally infiltrates into the native soils. Runoff from the site that doesn’t infiltrate or intercepted by the existing natural vegetation, sheet flows to catch basins in Yelm Avenue, Killion Road SE, and the northern private drive that conveys stormwater to offsite Contech structures. The proposed project will capture all runoff from the site to infiltrate runoff in bioretention basins in the developed condition. Minimum Requirement 5: On-Site Stormwater Management Because all nine minimum requirements are triggered by this new development project and is within the Urban Growth Area (UGA) on a parcel less than five acres, the applicant may choose to implement either the LID performance standard or List #2. There is no existing stormwater infrastructure on the site for the project to tie into, therefore, the project proposes to meet the LID performance standard through infiltration. Post-Construction Soil Quality and Depth (BMP T5.13) will be implemented via imported soils. Minimum Requirement 6: Runoff Treatment This project proposes more than 5,000 square feet of pollution-generating hard surface; therefore, runoff treatment is required for all TDAs. Refer to Section F of this report for details. Minimum Requirement 7: Flow Control Proposed TDAs 1 and 2 have a total of 10,000 square feet or more of effective impervious surfaces, therefore, flow control is required. The project will comply with this requirement by matching developed discharge durations to pre-developed durations for the range of pre-developed discharge rates from 50% of the 2-year peak flow up to the full 50-year peak flow (Flow Control Performance Standard). The Flow Control for the entire site is achieved through infiltration. Minimum Requirement 8: Wetlands Protection This minimum requirement does not apply to this site. No wetlands exist on-site and there are no direct or indirect discharges to wetlands through conveyance systems leaving the site. Minimum Requirement 9: Operations and Maintenance An operation and maintenance manual for the proposed stormwater management BMPs is included in Appendix H of this report. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Page 7 SECTION C - PRELIMINARY SOILS EVALUATION Data provided by the United States Department of Agriculture (USDA) National Resources Conservation Service (NRCS) Web Soil Survey (WSS), included in Attachment No. 4 in Appendix A, reports the site consists of Spanaway gravelly sandy loam with zero to three percent slopes. Spanaway gravelly sandy loam is within hydrologic soil group A, or soils having a high infiltration rate. Given the Type A soils present onsite, a design infiltration rate of 2 inches per hour was assumed to model and size the proposed drainage facilities. Infiltration rate is subject to change, the applicant is awaiting additional information from Geotech. Geotechnical investigations were conducted in March 2024 by Moore Twining Associates, Inc. The report is included in Appendix F. SECTION D - SOURCE CONTROL All development activities shall apply the Minimum Standards of SWMMWW I-3.4.3. The project is a proposed gas and diesel station that plans to store and use hazardous materials on-site. There will be refueling of vehicles on-site and vehicle storage will be for employee parking and trailer storage during construction. Trailers may contain chemicals or other hazardous materials and are not associated with oil leaks. Stormwater runoff in the refueling and loading areas will be captured on-site and conveyed to an oil/water separator before discharging to the proposed southern bioretention basin. Onsite grading is designed such that runoff from the fuel canopy is isolated to minimize the volume of stormwater passing through the oil/water separator. Stormwater treatment facilities will be cleaned and maintained per the operations and maintenance manual included in Appendix H of this report. Proper plant selection as well as weed control and proper disposal will be used on-site. Temporary Erosion and Sediment Control BMPs will be put in place prior to construction per the SWPPP included in Appendix G of this report. All BMPs under sections S407, S411, S425, S444, and S450 will be applied as operational source control to manage landscaped areas. SECTION E - ON-SITE STORMWATER MANAGEMENT BMPs Because all nine minimum requirements are triggered by this project and it is within the Urban Growth Area (UGA), this project is able to implement the LID performance standard or List #2 as discussed in section B. The LID performance standard will be met since the site is proposed to fully infiltrate all runoff from the site. Appendix B in this report contains preliminary Site, Utility, and Grading & Drainage Plans showing the location of the infiltration areas. Appendix D contains all the associated WWHM model inputs and results. SECTION F - RUNOFF TREATMENT ANALYSIS AND DESIGN The proposed site will be required to meet the basic level of treatment. The of the site proposed two bioretention basins as the selected BMP applicable for basic treatment. The bioretention areas have been designed with a 3:1 side slope. Stormwater will sheet flow to four grate inlets or curb cuts and swales where the stormwater will enter the bioretention facilities. The stormwater from the four grate inlets will be conveyed to the bioretention ponds via 6” or 8” HDPE storm drainpipe to a bubble up emitter structure. Runoff from the building and canopy roofs propose to be routed through underground pipes or sheet flow to the bioretention basins. Runoff from the pollution generating surfaces around the fuel station will be Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Page 8 captured through a separate system to an oil/water separator before discharging to the proposed southern bioretention basin. The proposed bioretention basins have been sized using the water quality flow rate modeled in Western Washington Hydrology Model (WWHM). See appendix D for the WWHM model reports. Appendix B contains the Site, Utility, and Grading & Drainage Plans showing the proposed bioretention areas. SECTION G - FLOW CONTROL ANALYSIS AND DESIGN As discussed in Section E of the report, full infiltration is feasible for the site. The stormwater infiltration basins will be constructed on top of proposed rock infiltration facilities with a bioretention soil mix. According to the NRCS WSS, soils that are appropriate for infiltration are located at the site. The construction of the proposed infiltration basins will generally include the soils being stripped down to reach the bottom of pond and up to five feet below to backfilled with clean washed drain rock with high void space and the bioretention soil mix. The infiltration facilities have been designed in WWHM to match 100 percent of the 2-year through the full 50-year design storm and infiltrate up to the 100-year design storm. The associated WWHM model files are located in Appendix D. SECTION H - WETLANDS PROTECTION No wetlands exist on-site and there are no direct or indirect discharges to wetlands through conveyance systems leaving the site, therefore, no wetland protection has been included in the design of this project. SECTION I - OTHER PERMITS This Preliminary Stormwater Report is required as part of the City of Yelm’s Civil Plan Review. A construction stormwater general permit (CSWGP) through the Department of Ecology (DOE) will be required as well. The application for the CSWGP must be received by the DOE at least 60 days prior to construction, with issuance of the permit approximately 45 days after the application is received. See Appendix G for a copy of the erosion control plans and details found in the SWPPP. SECTION J - CONVEYANCE SYSTEMS ANALYSIS AND DESIGN The project proposes to infiltrate on-site, therefore, there were no analyses done to size conveyance connections offsite. On-site, the building roof drains will discharge to grade and sheet flow directly into the northwest bioretention basin via proposed swale. The fuel station canopy roof drains will flow through pipes to the southern stormwater bioretention basin. Runoff from the pollution generating surfaces around the fuel station will be captured through a separate system to an oil/water separator before discharging to the proposed southern bioretention basin. The remainder of the site is proposed to sheet flow to the northwestern or southern bioretention basin. All stormwater collected onsite will remain and infiltrate. Refer to Appendix E for the onsite conveyance calculations. SECTION K - SPECIAL REPORTS AND STUDIES There are no special reports or studies at the time of this Stormwater Technical Information Report. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Page 9 SECTION L - OPERATIONS AND MAINTENANCE MANUAL Operations and maintenance procedures for stormwater management facilities are included in Appendix H. Beyond what is listed in the manufacturer operations and maintenance manuals, all facilities shall be inspected after the first major storm of the wet season and a minimum of twice per year. Clean any trash or debris from water quality facilities during the inspection and replace treatment media if conditions listed in the manufacturer maintenance manual are observed. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Appendix A: Maps and Photos 01/03/2024 VICINITY MAP PROJECT SITE N.T.S. KI L L I O N R O A D S E Y E L M A V E N U E / S R 5 1 0 TA H O M A B O U L E V A R D S E BERRY VALLEY ROAD SE TO R N A D O A L L E Y TERRA VIEW STREET SE 99TH AVENUE SE BER R Y V A L L E Y R O A D S E CU L L E N S S T R E E T N W LO N G M I R E S T R E E N W J E F F E R S O N S T N W T R U M P A V E N W MO U N T A I N V I E W R O A D S E KAYLA STREET SE IVERSON LOOP SE CU L L E N S S T R E E T S E Y E L M A V E N U E / S R 5 1 0 W A S H I N G T O N S T S W K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) Y E L M A V E N U E / S R 5 1 0 TDA2: 0.281 AC KI L L I O N R O A D S E TDA1: 0.313 AC TDA3: 1.02 AC TDA4: 0.463 AC TDA5: 0.204 AC NORTH K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) (ACCESS ROAD) 113'TRANSFORMER PAD (APPROX) W EXCAVATION HOLE 12 K D I E S E L ( 1 0 ' D I A . ) 8K CK CHOICE12K SUL 20K REGULAR > > > > > > >>>>>>>>>> > > >>>> UGE UGE UG E K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) S47 ° 0 4 ' 2 9 " W 87.3 ' N88°15'36"W 399.0' SOUTH BIORETENTION NORTH BIORETENTION TDA 1: 1.22 AC TDA 2: 1.02 AC BYPASS 1: 0.04 AC OIL/WATER SEPARATOR NORTH Hydrologic Soil Group—Thurston County Area, Washington (CK Yelm & Killion) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/20/2023 Page 1 of 4 51 9 9 4 6 0 51 9 9 4 8 0 51 9 9 5 0 0 51 9 9 5 2 0 51 9 9 5 4 0 51 9 9 5 6 0 51 9 9 5 8 0 51 9 9 4 6 0 51 9 9 4 8 0 51 9 9 5 0 0 51 9 9 5 2 0 51 9 9 5 4 0 51 9 9 5 6 0 51 9 9 5 8 0 528980 529000 529020 529040 529060 529080 529100 529120 529140 529160 528980 529000 529020 529040 529060 529080 529100 529120 529140 529160 46° 56' 56'' N 12 2 ° 3 7 ' 9 ' ' W 46° 56' 56'' N 12 2 ° 3 7 ' 0 ' ' W 46° 56' 52'' N 12 2 ° 3 7 ' 9 ' ' W 46° 56' 52'' N 12 2 ° 3 7 ' 0 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 40 80 160 240 Feet 0 10 20 40 60 Meters Map Scale: 1:877 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available 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: Jul 18, 2020—Jul 20, 2020 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. Hydrologic Soil Group—Thurston County Area, Washington (CK Yelm & Killion) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/20/2023 Page 2 of 4 Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 110 Spanaway gravelly sandy loam, 0 to 3 percent slopes A 2.4 100.0% Totals for Area of Interest 2.4 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Hydrologic Soil Group—Thurston County Area, Washington CK Yelm & Killion Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/20/2023 Page 3 of 4 Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—Thurston County Area, Washington CK Yelm & Killion Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/20/2023 Page 4 of 4 1 DWLRQDO)ORRG+D]DUG/D\HU),50HWWH ... 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GLJLWDOIORRGPDSVLILWLVQRWYRLGDVGHVFULEHGEHOF 4 y 7KHEDVHPDSVKRZQFRPSOLHVZLWK)(0$VEDVHPDS DFFXUDF\VWDQGDUGV 7KHIORRGKD]DUGLQIRUPDWLRQLVGHULYHGGLUHFWO\IUR i smpDXWKRULWDWLYH1)+/ZHEVHUYLFHVSURYLGHGE\)(0$7KLVF + �► r' ' .a ZDVH[SRUWHGROO DQGGRHVQRW 4p ilk � - UHIOHFWFKDQJHVRUDPHQGPHQWWXEVHTXHQWWRWKLV z PI!'4" a-P WLPH7KH1)+/DQGHIIHFWLYHLQIRUPDWLRQPD\FKDQJHRU • . •' k t EHFRPHVXSHUVHGHGE\QHZGDWDRYHUWLPH { s r * t - 7KLVPDSLPDJHLVYRLGLIWKHRQHRUPRUHRIWKHIROORZLQ HOHPHQWVGRQRWDSSHDUEDVHPDSLPDJHU\IORRG]RQHOI J i OHJHQGVFDOHEDUPDSFUHDWLRQGDWHFRPPXQLW\LGHQ\ )HHW f f1 XQPDSS GDQGXQPRGHUQL]HGDUHDVF QQRWEHXVHGIRI UHJXODWRU\SXUSRVHV %DVHPDS,PDJHU\6RXUFH86*61 DWLRQDOODS Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Preliminary Stormwater Report December 2023 Downstream Analysis: TDA 1, TDA 3 & TDA 4 Yelm Avenue Catch Basins and Downstream Contech Storm Manholes First Catch Basin along Yelm Avenue. Catch Basin was Clean, Free of Debris, and No Standing Water. Second Catch Basin along Yelm Avenue. Catch Basin was Clean, Free of Debris, and No Standing Water. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Preliminary Stormwater Report December 2023 Third Catch Basin along Yelm Avenue. Catch Basin was Clean, Free of Debris, and Low Standing Water. Fourth Catch Basin along Yelm Avenue Adjacent to Site. Catch Basin was Clean, Free of Debris, and Low Standing Water. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Preliminary Stormwater Report December 2023 Subsequent Catch Basins Downstream of the Site along Yelm Avenue were Clean, Free of Debris, and Low Standing Water. The Downstream Ended at Two Contech Stormwater Solutions Manholes. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Preliminary Stormwater Report December 2023 Downstream Analysis: TDA 2 North Private Drive Catch Basins Northeast Catch Basin on Private Drive. Natural Debris and High Standing Water. Northwest Catch Basin on Private Drive. Natural Debris and High Standing Water Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Preliminary Stormwater Report December 2023 Downstream Analysis: TDA 5 Killion Road SE Catch Basins and Downstream Contech Storm Manholes Catch Basin at Intersection of Killion Road SE and Yelm Avenue. Well Maintained with Minimal Natural Debris and Standing Water. Catch Basin North of Intersection of Killion Road SE and Yelm Avenue. Well Maintained with Minimal Natural Debris and Standing Water. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Preliminary Stormwater Report December 2023 Stormwater Treatment Solutions Manhole Downstream & East of Proposed Development on Killion Road SE. End of Downstream Analysis for TDA 5 Drain Manhole. East of Proposed Development on Killion Road SE. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Appendix B: Site Plan, Utility Plan, and Grading & Drainage Plan K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) (ACCESS ROAD) 113' CA N O P Y ℄ BL D G . ℄ TRANSFORMER PAD (APPROX) W EXCAVATION HOLE 12 K D I E S E L ( 1 0 ' D I A . ) 8K CK CHOICE12K SUL 20K REGULAR S47 ° 0 4 ' 2 9 " W 87.3 ' N88°15'36"W 399.0' 11.1' 11.0'5.0'9.5' (TYP) 5.0' 28.0' (TYP) 6.0' 20.0' 45.0' 24.0' 12.0'10.5' 5.0' 7.5' 36.5' 11.1' 50.0' 5.0' 12.0' 55.0' 43.5' 5.0' 6.0' 55.0' 6.0' (TYP) 13.7' 10.3' 36.0' 15.5' 34.0' 14.0' 26.0' 8.3'87.1' 36.1' 49.8' 12.0' R10.0' R3.0' R3.0' (TYP) R3.0' R10.0'R10.0'R25.0' R30.0' R10.0' R46.0' R45.0' 40.0' 21.0' 40.0' 95.3' 5556 SI T E P L A N C4.0 NORTH © CI R C L E K - Y E L M & KI L L O N PR E P A R E D F O R CI R C L E K S T O R E S , I N C . PR E L I M I N A R Y , N O T FO R C O N S T R U C T I O N # LEGEND PARKING / SITE DATA THURSTON COUNTY 21 SPACES 1 SPACE 21 SPACES 1 SPACE REQUIRED PROVIDED N/A 44.7% 1.30 AC ±5,200 SF 102,366 SF / 2.35 AC FUELING STATION WITH CONVENIENCE STORE C-1 5%N/A N/A 4 CONSTRUCTION NOTES Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) > > > >>>>>>> > > > S47 ° 0 4 ' 2 9 " W 87.3 ' N88°15'36"W C5 . 2 1 BIORETENTION 1 BOTTOM AREA: 1,098 SF BOTTOM ELEV: 346.00 TOP ELEV: 349.50 SIDE SLOPE: 3:1 350.91 SW 350.85 TC 350.35 BC 351.02 TC 350.52 BC 352.13 TC 351.63 BC 352.49 TC 351.99 BC 352.56 TC 352.06 BC 352.90 TC 352.40 BC 353.20 TC 352.70 BC 353.35 TC 352.85 BC 353.76 TC 353.26 BC 353.19 SW 353.07 SW 353.46 SW 353.29 TC 352.79 BC 353.31 TC 352.81 BC 353.28 TC 352.78 BC 353.51 TC 353.01 BC 353.76 TC 353.26 BC 353.50 TC 353.00 BC 351.65 TC 351.15 BC 350.86 FL 351.55 TC 351.05 BC 351.23 TC 350.73 BC 351.31 TC 350.81 BC 350.00 FL 352.17 TC 351.67 BC 353.20 TC 352.70 BC 2.0 4 % 1.6 8 % 1.49 % 1. 7 6 % 1. 5 3 % 1 . 5 1 % 6.87 % 351.98 FL 350.83 SW 346.00 FG 126 LF OF @ 2.56% 81 LF OF @ 0.56% 8. 2 6 % 1. 7 5 % 1. 7 6 % 1.8 2 % 11 353.28 SW 353.44 SW 353.45 SW 353.36 SW 353.23 SW 7 1 13 LF OF @ 6.50% 10 10 7 33 . 0 1 % 33 . 3 3 % 33. 3 3 % 33.33% 352.35 FG 352.66 FG 353.51 TC 353.01 BC 353.48 TC 352.98 BC 353.32 TC 352.82 BC 353.20 SW 353.07 SW 353.35 SW 353.45 SW 353.18 SW 353.31 SW 351.36 TC 350.86 BC 351.36 TC 350.86 BC 351.59 FL 352.05 FL 349.50 FL 350.06 FL 351.06 TC 350.56 BC 351.08 SW ME 351.02 SW ME 350.96 TC ME 350.46 BC ME 350.75 SW 350.84 SW 350.54 ME 353.02 SW 353.07 SW 353.51 SW 2 0 . 0 ' B . S . L . 20 . 0 ' B . S . L . 15. 0 ' B . S . L . 10. 0 ' P S E EAS E M E N T 350.49 ME 1.89 % 353.13 SW 5.4 7 % 351.37 TC 350.87 BC 10 9 CB-01 RIM: 352.05 INV OUT: 349.22 CB-02 RIM: 351.59 INV OUT: 348.76 INV: 346.00 5 5 3 3 349.40 FL 1 1 1 . 6 1 % 7. 4 0 % 1 . 8 8 % 1.76 % 353.06 SW 351.21 SW ME 351.24 SW ME 351.10 TC ME 350.60 BC ME FFE = 353.50 12(TYP.) GR A D I N G P L A N C5.0 © CI R C L E K - Y E L M & KI L L O N PR E P A R E D F O R CI R C L E K S T O R E S , I N C . PR E L I M I N A R Y , N O T FO R C O N S T R U C T I O N NORTH 1950 1950 1.00% FG ME TC FFE BC 1.PRIVATE CURB RAMPS ON THE SITE (I.E. OUTSIDE PUBLIC STREET RIGHT-OF-WAY) SHALL CONFORM TO ADA STANDARDS AND SHALL HAVE A DETECTABLE WARNING SURFACE THAT IS FULL WIDTH AND FULL DEPTH OF THE CURB RAMP, NOT INCLUDING FLARES. 2.ALL ACCESSIBLE ROUTES, GENERAL SITE AND BUILDING ELEMENTS, RAMPS, CURB RAMPS, STRIPING, AND PAVEMENT MARKINGS SHALL CONFORM TO ADA STANDARDS FOR ACCESSIBLE DESIGN, LATEST EDITION. 3.BEFORE PLACING PAVEMENT, CONTRACTOR SHALL VERIFY THAT SUITABLE ACCESSIBLE PEDESTRIAN ROUTES (PER ADA AND SPOKANE COUNTY) EXIST TO AND FROM EVERY DOOR AND ALONG SIDEWALKS, ACCESSIBLE PARKING SPACES, ACCESS AISLES, AND ACCESSIBLE ROUTES. IN NO CASE SHALL AN ACCESSIBLE RAMP SLOPE EXCEED 1 VERTICAL TO 12 HORIZONTAL. IN NO CASE SHALL SIDEWALK CROSS SLOPE EXCEED 2.0 PERCENT. IN NO CASE SHALL LONGITUDINAL SIDEWALK SLOPE EXCEED 5.0 PERCENT. ACCESSIBLE PARKING SPACES AND ACCESS AISLES SHALL NOT EXCEED 2.0 PERCENT SLOPE IN ANY DIRECTION. 4.CONTRACTOR SHALL TAKE FIELD SLOPE MEASUREMENTS ON FINISHED SUBGRADE AND FORM BOARDS PRIOR TO PLACING PAVEMENT TO VERIFY THAT ADA SLOPE REQUIREMENTS ARE PROVIDED. CONTRACTOR SHALL CONTACT ENGINEER PRIOR TO PAVING IF ANY EXCESSIVE SLOPES ARE ENCOUNTERED. NO CONTRACTOR CHANGE ORDERS WILL BE ACCEPTED FOR ADA SLOPE COMPLIANCE ISSUES. 5.ALL PEDESTRIAN SIDEWALKS, PATHWAYS, AND CROSSWALKS SHALL BE CONSTRUCTED NOT TO EXCEED MAX, 2.0 PERCENT CROSS SLOPE, MAX 5.0 PERCENT RUNNING SLOPE. 6.ALL HANDICAP ACCESSIBLE PARKING SPACES SHALL BE CONSTRUCTED NOT TO EXCEED MAX 2.0 PERCENT CROSS SLOPE IN ALL DIRECTIONS. 7.PROPOSED GRADES TO MATCH EXISTING ELEVATIONS AT PROPERTY LINE. 8.CONTRACTOR TO FIELD VERIFY ELEVATIONS AT ALL EXISTING SIDEWALK AND ROAD CONNECTION POINTS WITH ENGINEER OF RECORD BEFORE CONSTRUCTION OF ANY IMPROVEMENTS. 9.FOR EROSION CONTROL NOTES REFER TO SHEET C3.0 - EROSION & SEDIMENT CONTROL PLAN. 10.CONTRACTOR TO ENSURE ADEQUATE COVER REMAINS OVER ALL EXISTING UTILITIES. 11.CONTRACTOR TO VERIFY EXISTING COVER OVER ALL UTILITIES BEFORE START OF CONSTRUCTION AND TO COORDINATE WITH THE ENGINEER OF RECORD PRIOR TO START OF CONSTRUCTION IF DESIGN DOES NOT PROVIDE 36" COVER. 12.ALL EXISTING VALVES, BOXES, MANHOLE LIDS, COVERS, AND SIMILAR APPURTENANCES MUST BE ADJUSTED ACCORDINGLY TO MATCH FINISHED GRADE. 13.MINIMUM 48" SUBGRADE INFILTRATION BENEATH 12-18" OF TREATMENT SOIL PER SECTION 6.7.1 OF THE SRSM. NOTES LEGEND MA T C H L I N E : S E E S H E E T C5 . 1 SW GRADING AND DRAINAGE NOTES 1950 K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) UGE UGE UGE UGE UG E UG E K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) (ACCESS ROAD) 113' CA N O P Y ℄ BL D G . ℄ TRANSFORMER PAD (APPROX) W EXCAVATION HOLE 12 K D I E S E L ( 1 0 ' D I A . ) 8K CK CHOICE12K SUL 20K REGULAR > > > > > > > > > >>>>>>>>>>> >>>>>> N88°15'36"W 399.0' C5 . 2 2 353.76 TC 353.26 BC 353.75 TC 353.25 BC 353.50 TC 353.00 BC 353.47 TC 352.97 BC 353.60 TC 353.10 BC 353.60 TC 353.10 BC 353.76 TC 353.26 BC 353.04 FG 353.55 TC 353.05 BC 353.30 SW 353.29 SW 353.94 TC 353.44 BC 353.97 TC 353.47 BC 354.08 TC 353.58 BC 354.13 TC 353.63 BC 354.62 TC 354.12 BC 354.60 TC 354.10 BC 354.76 TC 354.26 BC 354.32 SW 355.16 SW ME 354.16 SW 354.53 TC 354.03 BC 354.16 TC 353.66 BC 353.64 TC 353.14 BC 352.83 TC 352.33 BC 351.65 TC 351.15 BC 353.05 FL 352.80 FL 1. 7 6 % 1. 5 3 % 1.1 6 % 1. 2 5 % 1.1 8 % 2.14 % 1.71 %0.97 % 1.6 8 % 1.29 % 17. 1 1 % 8. 6 9 % 345.70 FG 1.4 1 % 1.1 3 % 354.72 SW 355.18 TC 354.68 BC 354.59 TC 354.09 BC 351.98 FL 352.42 FL 2 . 2 7 % 75 LF OF @ 5.92% 353.46 SW 353.42 SW 1. 7 5 % 1.8 2 % 3 . 1 6 % 4353.44 SW 355.34 SW ME 7 4 LF OF @ 6.50% 13 LF OF @ 6.50% 19 LF OF @ 6.50% 10 10 351.64 FL 353.31 SW 353.31 SW 353.29 SW 353.29 SW 353.38 SW 353.39 SW 353.61 SW 354.29 SW 354.38 SW 352.13 TC 351.63 BC 352.16 TC 351.66 BC 353.99 TC 353.49 BC 352.38 FL 353.45 TC 352.95 BC 353.05 FG 353.31 FL 353.76 TC 353.26 BC 353.67 SW 351.97 FL 352.01 FL 353.33 SW 353.38 SW 15.0' B.S.L. 1 5 . 0 ' P S E E A S E M E N T FFE = 353.50 353.44 SW BIORETENTION 2 BOTTOM AREA: 1,199 SF BOTTOM ELEV: 345.70 TOP ELEV: 349.20 SIDE SLOPE: 3:1 11 10 10 10 10 9 9 9 9 CB-04 RIM: 352.80 INV OUT: 350.13 CB-03 RIM: 351.17 INV IN: 348.31 INV OUT: 348.31 OIL/WATER SEPARATOR RIM: 349.17 INV IN: 348.06 INV OUT: 348.06 INV: 345.70 INV: 345.70 INV: 347.78 INV: 346.92 6 5 5 4 3 4 LF OF @ 6.49% 3 3 3 2 1 349.40 FL 349.20 FL 1 1 353.92 TC 353.42 BC 355.59 FG 355.71 FG 355.28 FG 355.38 SW ME 356.09 SW ME 355.70 SW ME 33.33% 33 . 3 3 % 33 . 3 3 % 33.33% 354.84 SW ME 354.85 SW ME 354.81 TC ME 354.31 BC ME 354.30 SW ME 354.69 SW 353.78 SW ME 353.75 SW ME 354.20 TC ME 353.70 BC ME 354.12 SW ME 354.40 SW ME 354.12 SW 1 353.19 FL 354.44 FL FFE = 353.50 12 (TYP.)GR A D I N G P L A N C5.1 NORTH © CI R C L E K - Y E L M & KI L L O N PR E P A R E D F O R CI R C L E K S T O R E S , I N C . PR E L I M I N A R Y , N O T FO R C O N S T R U C T I O N 1.PRIVATE CURB RAMPS ON THE SITE (I.E. OUTSIDE PUBLIC STREET RIGHT-OF-WAY) SHALL CONFORM TO ADA STANDARDS AND SHALL HAVE A DETECTABLE WARNING SURFACE THAT IS FULL WIDTH AND FULL DEPTH OF THE CURB RAMP, NOT INCLUDING FLARES. 2.ALL ACCESSIBLE ROUTES, GENERAL SITE AND BUILDING ELEMENTS, RAMPS, CURB RAMPS, STRIPING, AND PAVEMENT MARKINGS SHALL CONFORM TO ADA STANDARDS FOR ACCESSIBLE DESIGN, LATEST EDITION. 3.BEFORE PLACING PAVEMENT, CONTRACTOR SHALL VERIFY THAT SUITABLE ACCESSIBLE PEDESTRIAN ROUTES (PER ADA AND SPOKANE COUNTY) EXIST TO AND FROM EVERY DOOR AND ALONG SIDEWALKS, ACCESSIBLE PARKING SPACES, ACCESS AISLES, AND ACCESSIBLE ROUTES. IN NO CASE SHALL AN ACCESSIBLE RAMP SLOPE EXCEED 1 VERTICAL TO 12 HORIZONTAL. IN NO CASE SHALL SIDEWALK CROSS SLOPE EXCEED 2.0 PERCENT. IN NO CASE SHALL LONGITUDINAL SIDEWALK SLOPE EXCEED 5.0 PERCENT. ACCESSIBLE PARKING SPACES AND ACCESS AISLES SHALL NOT EXCEED 2.0 PERCENT SLOPE IN ANY DIRECTION. 4.CONTRACTOR SHALL TAKE FIELD SLOPE MEASUREMENTS ON FINISHED SUBGRADE AND FORM BOARDS PRIOR TO PLACING PAVEMENT TO VERIFY THAT ADA SLOPE REQUIREMENTS ARE PROVIDED. CONTRACTOR SHALL CONTACT ENGINEER PRIOR TO PAVING IF ANY EXCESSIVE SLOPES ARE ENCOUNTERED. NO CONTRACTOR CHANGE ORDERS WILL BE ACCEPTED FOR ADA SLOPE COMPLIANCE ISSUES. 5.ALL PEDESTRIAN SIDEWALKS, PATHWAYS, AND CROSSWALKS SHALL BE CONSTRUCTED NOT TO EXCEED MAX, 2.0 PERCENT CROSS SLOPE, MAX 5.0 PERCENT RUNNING SLOPE. 6.ALL HANDICAP ACCESSIBLE PARKING SPACES SHALL BE CONSTRUCTED NOT TO EXCEED MAX 2.0 PERCENT CROSS SLOPE IN ALL DIRECTIONS. 7.PROPOSED GRADES TO MATCH EXISTING ELEVATIONS AT PROPERTY LINE. 8.CONTRACTOR TO FIELD VERIFY ELEVATIONS AT ALL EXISTING SIDEWALK AND ROAD CONNECTION POINTS WITH ENGINEER OF RECORD BEFORE CONSTRUCTION OF ANY IMPROVEMENTS. 9.FOR EROSION CONTROL NOTES REFER TO SHEET C3.0 - EROSION & SEDIMENT CONTROL PLAN. 10.CONTRACTOR TO ENSURE ADEQUATE COVER REMAINS OVER ALL EXISTING UTILITIES. 11.CONTRACTOR TO VERIFY EXISTING COVER OVER ALL UTILITIES BEFORE START OF CONSTRUCTION AND TO COORDINATE WITH THE ENGINEER OF RECORD PRIOR TO START OF CONSTRUCTION IF DESIGN DOES NOT PROVIDE 36" COVER. 12.ALL EXISTING VALVES, BOXES, MANHOLE LIDS, COVERS, AND SIMILAR APPURTENANCES MUST BE ADJUSTED ACCORDINGLY TO MATCH FINISHED GRADE. 13.MINIMUM 48" SUBGRADE INFILTRATION BENEATH 12-18" OF TREATMENT SOIL PER SECTION 6.7.1 OF THE SRSM. NOTES MA T C H L I N E : S E E S H E E T C5 . 0 1950 1950 1.00% FG ME TC FFE BC LEGEND SW 1950 GRADING AND DRAINAGE NOTES TY P I C A L D R A I N A G E CR O S S S E C T I O N S C5.2 © CI R C L E K - Y E L M & KI L L O N PR E P A R E D F O R CI R C L E K S T O R E S , I N C . PR E L I M I N A R Y , N O T FO R C O N S T R U C T I O N BIORETENTION POND 1 - WEST TO EAST PROFILE1 C5.2 NOT TO SCALE BIORETENTION BASIN 2 - EAST TO WEST PROFILE2 C5.2 NOT TO SCALE K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) UGE UGE UG E S47 ° 0 4 ' 2 9 " W 87.3 ' N88°15'36"W 399.0' K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) (ACCESS ROAD) 113' CA N O P Y ℄ BL D G . ℄ TRANSFORMER PAD (APPROX) W EXCAVATION HOLE 12 K D I E S E L ( 1 0 ' D I A . ) 8K CK CHOICE12K SUL 20K REGULAR UT I L I T Y P L A N C6.0 NORTH © CI R C L E K - Y E L M & KI L L O N PR E P A R E D F O R CI R C L E K S T O R E S , I N C . PR E L I M I N A R Y , N O T FO R C O N S T R U C T I O N LEGEND DOMESTIC WATER CONSTRUCTION NOTES GENERAL NOTES DRY UTILITY CONSTRUCTION NOTES SANITARY SEWER CONSTRUCTION NOTES STORM DRAIN CONSTRUCTION NOTES UGE UGE UTILITY NOTES 1.SEE MEP PLANS FOR ALL UTILITY CONNECTIONS INTO BUILDING. 2.REFER TO CITY OF YELM STANDARD AND DETAILS FOR TRENCHING, BEDDING, BACKFILL, AND TRENCH COMPACTION REQUIREMENTS. 3.REFER TO ARCHITECTURAL/MEP PLANS FOR LOCATION AND SIZING OF SLEEVES FOR FRANCHISE UTILITIES, IRRIGATION, ETC. 4.CONTRACTOR SHALL NOTIFY THE UTILITY AUTHORITIES INSPECTORS 72 HOURS BEFORE CONNECTING TO ANY EXISTING LINE. 5.SANITARY SEWER PIPE SHALL BE AS FOLLOWS: PRIVATE: PVC SDR 35 PER ASTM D 3034 6.WATER LINES SHALL BE AS FOLLOWS: PRIVATE (2 INCH): HIGH DENSITY POLYETHYLENE (HDPE), 200 PSI, CTS, SDR 9, OR TYPE "K" COPPER PRIVATE (SMALLER THAN 2 INCHES): SEAMLESS, SOFT-ANNEALED, TYPE "K" SOFT COPPER, ASTM B88 8.CONTRACTOR IS RESPONSIBLE FOR COMPLYING TO THE SPECIFICATIONS OF THE CITY OF YELM WITH REGARDS TO MATERIALS AND INSTALLATION OF UTILITIES AND UTILITY CROSSINGS. 9.IT IS THE CONTRACTOR'S RESPONSIBILITY TO DEFLECT ELECTRIC, GAS, CABLE, AND TELEPHONE CONDUIT AND PIPING AS REQUIRED TO AVOID UTILITY CONFLICTS. 10.THE CONTRACTOR IS SPECIFICALLY CAUTIONED THAT THE LOCATION AND/OR ELEVATION OF EXISTING UTILITIES AS SHOWN ON THESE PLANS IS BASED ON RECORDS OF THE VARIOUS UTILITY COMPANIES, AND WHERE POSSIBLE, MEASUREMENTS TAKEN IN THE FIELD. THE INFORMATION IS NOT TO BE RELIED ON AS BEING EXACT OR COMPLETE. THE CONTRACTOR MUST CALL THE APPROPRIATE UTILITY COMPANIES AT LEAST 72 HOURS BEFORE ANY EXCAVATION TO REQUEST EXACT FIELD LOCATION OF UTILITIES. IT SHALL BE THE RESPONSIBILITY OF THE CONTRACTOR TO RELOCATE ALL EXISTING UTILITIES WHICH CONFLICT WITH THE PROPOSED IMPROVEMENTS SHOWN ON THE PLANS. 11.CONTRACTOR IS RESPONSIBLE FOR ALL NECESSARY PERMITS, INSPECTIONS AND/OR CERTIFICATIONS REQUIRED BY CITY CODES AND/OR UTILITY SERVICE COMPANIES. 12.CONTRACTOR SHALL COORDINATE WITH ALL UTILITY COMPANIES FOR INSTALLATION REQUIREMENTS AND SPECIFICATIONS IN REGARDS TO TAPS, HYDRANTS, VALVES, ETC. 13.CONTRACTOR IS RESPONSIBLE FOR PAVEMENT REPLACEMENT REQUIRED FOR ALL UTILITY INSTALLATIONS PER CITY STANDARDS. 14.CONTRACTOR SHALL MAINTAIN A MINIMUM OF 3 FEET COVER ON ALL WATER LINES OR AS PER CITY OF YELM REQUIREMENTS. © CI R C L E K - Y E L M & KI L L O N PR E P A R E D F O R CI R C L E K S T O R E S , I N C . PR E L I M I N A R Y , N O T FO R C O N S T R U C T I O N Pl o t t e d B y : Ch i s h o l m , T a r y n S h e e t S e t : CK Y E L M C D s L a y o u t : C7 . 2 D E T A I L S Oc t o b e r 3 1 , 2 0 2 4 0 9 : 3 1 : 1 2 a m K: \ S E A _ C i v i l \ S E A _ D S \ 0 9 0 0 9 0 - C i r c l e K W A \ 0 9 0 0 9 0 0 0 0 - C i r c l e K Y e l m A v e & K i l l o n \ C A D \ P l a n S h e e t s \ C o n s t r u c t i o n D o c u m e n t s \ C 7 . 0 - D E T A I L S . d w g DE T A I L S C7.2 VARIES' A PLAN SECTION A-A A CURB CUT CURB CURB CUT GEOTEXTILE NOTES: 1. THE FILTER FABRIC SHALL MEET THE REQUIREMENTS IN MATERIAL SPECIFICATIONS 592 GEOTEXTILE TABLE 1 OR 2, CLASS I, II, OR III. 2. THE RIPRAP SHALL BE PLACED ACCORDING TO CONSTRUCTION SPECIFICATION 61 LOOSE ROCK RIPRAP. THE ROCK MAY BE EQUIPMENT PLACED. BOTTOM OF CURB PER PLAN PROPOSED 6" CURB RIP RAP TO PROVIDE SCOUR PROTECTION TO VEGETATIVE SWALES GEOTEXTILE TO BE INSTALLED UNDER RIP RAP VAR I E S 0.5' 1 . 0 ' 1.0' CURB CUT #4 BARS 18" O.C. 6" PER PLAN 1" 1" BATTER 1/2" R NOTE: CONCRETE SHALL BE 3000 PSI. SEE DETAIL 1 HEREON FOR HD CONCRETE BASE AND SUBGRADE PREPARATION. VALLEY GUTTER Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Appendix C: Special Reports & Studies There are no special reports or studies at the time of this Stormwater Technical Information Report. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Appendix D: Flow Control and Water Quality Calculations WWHM2012 PROJECT REPORT CK Yelm & Killion 10/31/2024 7:26:43 AM Page 2 General Model Information WWHM2012 Project Name:CK Yelm & Killion Site Name:CK Yelm Site Address: City:Yelm Report Date:10/31/2024 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 Version:4.3.1 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year CK Yelm & Killion 10/31/2024 7:26:43 AM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre A B, Forest, Flat 2.28 Pervious Total 2.28 Impervious Land Use acre Impervious Total 0 Basin Total 2.28 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 1 POC 1 CK Yelm & Killion 10/31/2024 7:26:43 AM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre A B, Lawn, Flat 0.56 Pervious Total 0.56 Impervious Land Use acre ROADS FLAT 0.45 ROOF TOPS FLAT 0.125 SIDEWALKS FLAT 0.085 Impervious Total 0.66 Basin Total 1.22 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Surface retention 1 Surface retention 1 CK Yelm & Killion 10/31/2024 7:26:43 AM Page 5 Basin 2 Bypass:No GroundWater:No Pervious Land Use acre A B, Lawn, Flat 0.39 Pervious Total 0.39 Impervious Land Use acre ROADS FLAT 0.62 SIDEWALKS FLAT 0.01 Impervious Total 0.63 Basin Total 1.02 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Surface retention 2 Surface retention 2 CK Yelm & Killion 10/31/2024 7:26:43 AM Page 6 Basin 3 Bypass:Yes GroundWater:No Pervious Land Use acre A B, Lawn, Flat 0.04 Pervious Total 0.04 Impervious Land Use acre Impervious Total 0 Basin Total 0.04 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 1 POC 1 CK Yelm & Killion 10/31/2024 7:26:43 AM Page 7 Routing Elements Predeveloped Routing CK Yelm & Killion 10/31/2024 7:26:43 AM Page 8 Mitigated Routing Bioretention 1 Bottom Length: 90.00 ft. Bottom Width: 12.00 ft. Material thickness of first layer: 1.5 Material type for first layer: SMMWW Material thickness of second layer: 1.5 Material type for second layer: GRAVEL Material thickness of third layer: 0 Material type for third layer: GRAVEL Infiltration On Infiltration rate:2 Infiltration safety factor:1 Total Volume Infiltrated (ac-ft.):109.357 Total Volume Through Riser (ac-ft.):0 Total Volume Through Facility (ac-ft.):109.357 Percent Infiltrated:100 Total Precip Applied to Facility:9.732 Total Evap From Facility:3.881 Underdrain not used Discharge Structure Riser Height:3 ft. Riser Diameter:18 in. Element Outlets: Outlet 1 Outlet 2 Outlet Flows To: Bioretention Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.0744 0.0000 0.0000 0.0000 0.0714 0.0730 0.0007 0.0000 0.0000 0.1429 0.0717 0.0015 0.0000 0.0000 0.2143 0.0703 0.0023 0.0000 0.0002 0.2857 0.0690 0.0031 0.0000 0.0004 0.3571 0.0677 0.0039 0.0000 0.0007 0.4286 0.0664 0.0048 0.0000 0.0012 0.5000 0.0651 0.0057 0.0000 0.0019 0.5714 0.0638 0.0066 0.0000 0.0025 0.6429 0.0625 0.0076 0.0000 0.0027 0.7143 0.0612 0.0086 0.0000 0.0036 0.7857 0.0600 0.0096 0.0000 0.0048 0.8571 0.0587 0.0107 0.0000 0.0062 0.9286 0.0574 0.0118 0.0000 0.0078 1.0000 0.0562 0.0129 0.0000 0.0096 1.0714 0.0550 0.0140 0.0000 0.0112 1.1429 0.0537 0.0152 0.0000 0.0117 1.2143 0.0525 0.0164 0.0000 0.0140 1.2857 0.0513 0.0177 0.0000 0.0166 1.3571 0.0501 0.0190 0.0000 0.0194 1.4286 0.0489 0.0203 0.0000 0.0225 1.5000 0.0477 0.0217 0.0000 0.0259 1.5714 0.0466 0.0231 0.0000 0.0284 1.6429 0.0454 0.0246 0.0000 0.0296 1.7143 0.0442 0.0261 0.0000 0.0335 CK Yelm & Killion 10/31/2024 7:26:43 AM Page 9 1.7857 0.0431 0.0276 0.0000 0.0375 1.8571 0.0419 0.0292 0.0000 0.0500 1.9286 0.0408 0.0308 0.0000 0.0500 2.0000 0.0397 0.0324 0.0000 0.0500 2.0714 0.0386 0.0341 0.0000 0.0500 2.1429 0.0374 0.0358 0.0000 0.0500 2.2143 0.0363 0.0376 0.0000 0.0500 2.2857 0.0353 0.0394 0.0000 0.0500 2.3571 0.0342 0.0412 0.0000 0.0500 2.4286 0.0331 0.0431 0.0000 0.0500 2.5000 0.0320 0.0450 0.0000 0.0500 2.5714 0.0310 0.0470 0.0000 0.0500 2.6429 0.0299 0.0489 0.0000 0.0500 2.7143 0.0289 0.0510 0.0000 0.0500 2.7857 0.0278 0.0530 0.0000 0.0500 2.8571 0.0268 0.0551 0.0000 0.0500 2.9286 0.0258 0.0573 0.0000 0.0500 3.0000 0.0248 0.0595 0.0000 0.0500 Bioretention Surface Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)To Amended(cfs)Infilt(cfs) 3.0000 0.0744 0.0595 0.0000 0.0375 0.0000 3.0714 0.0757 0.0648 0.0000 0.0375 0.0000 3.1429 0.0771 0.0703 0.0000 0.0411 0.0000 3.2143 0.0785 0.0758 0.0000 0.0429 0.0000 3.2857 0.0799 0.0815 0.0000 0.0446 0.0000 3.3571 0.0813 0.0873 0.0000 0.0464 0.0000 3.4286 0.0827 0.0931 0.0000 0.0482 0.0000 3.5000 0.0841 0.0991 0.0000 0.0500 0.0000 3.5714 0.0855 0.1051 0.0000 0.0500 0.0000 3.6429 0.0869 0.1113 0.0000 0.0500 0.0000 3.7143 0.0884 0.1175 0.0000 0.0500 0.0000 3.7857 0.0898 0.1239 0.0000 0.0500 0.0000 3.8571 0.0913 0.1304 0.0000 0.0500 0.0000 3.9286 0.0927 0.1369 0.0000 0.0500 0.0000 4.0000 0.0942 0.1436 0.0000 0.0500 0.0000 4.0714 0.0957 0.1504 0.0000 0.0500 0.0000 4.1429 0.0972 0.1573 0.0000 0.0500 0.0000 4.2143 0.0987 0.1643 0.0000 0.0500 0.0000 4.2857 0.1002 0.1714 0.0000 0.0500 0.0000 4.3571 0.1017 0.1786 0.0000 0.0500 0.0000 4.4286 0.1032 0.1859 0.0000 0.0500 0.0000 4.5000 0.1048 0.1934 0.0000 0.0500 0.0000 4.5714 0.1063 0.2009 0.0000 0.0500 0.0000 4.6429 0.1078 0.2085 0.0000 0.0500 0.0000 4.7143 0.1094 0.2163 0.0000 0.0500 0.0000 4.7857 0.1110 0.2242 0.0000 0.0500 0.0000 4.8571 0.1125 0.2321 0.0000 0.0500 0.0000 4.9286 0.1141 0.2402 0.0000 0.0500 0.0000 5.0000 0.1157 0.2484 0.0000 0.0500 0.0000 5.0714 0.1173 0.2568 0.0000 0.0500 0.0000 5.1429 0.1189 0.2652 0.0000 0.0500 0.0000 5.2143 0.1205 0.2738 0.0000 0.0500 0.0000 5.2857 0.1221 0.2824 0.0000 0.0500 0.0000 5.3571 0.1238 0.2912 0.0000 0.0500 0.0000 5.4286 0.1254 0.3001 0.0000 0.0500 0.0000 5.5000 0.1271 0.3091 0.0000 0.0500 0.0000 5.5714 0.1287 0.3183 0.0000 0.0500 0.0000 CK Yelm & Killion 10/31/2024 7:26:43 AM Page 10 5.6429 0.1304 0.3275 0.0000 0.0500 0.0000 5.7143 0.1321 0.3369 0.0000 0.0500 0.0000 5.7857 0.1337 0.3464 0.0000 0.0500 0.0000 5.8571 0.1354 0.3560 0.0000 0.0500 0.0000 5.9286 0.1371 0.3657 0.0000 0.0500 0.0000 6.0000 0.1388 0.3756 0.0000 0.0500 0.0000 6.0714 0.1406 0.3856 0.3035 0.0500 0.0000 6.1429 0.1423 0.3957 0.8548 0.0500 0.0000 6.2143 0.1440 0.4059 1.5529 0.0500 0.0000 6.2857 0.1458 0.4162 2.3387 0.0500 0.0000 6.3571 0.1475 0.4267 3.1538 0.0500 0.0000 6.4286 0.1493 0.4373 3.9390 0.0500 0.0000 6.5000 0.1510 0.4480 4.6391 0.0500 0.0000 6.5000 0.1510 0.4480 5.2124 0.0500 0.0000 CK Yelm & Killion 10/31/2024 7:26:43 AM Page 11 Bioretention 2 Bottom Length: 99.00 ft. Bottom Width: 12.00 ft. Material thickness of first layer: 1.5 Material type for first layer: SMMWW Material thickness of second layer: 1.5 Material type for second layer: GRAVEL Material thickness of third layer: 0 Material type for third layer: GRAVEL Infiltration On Infiltration rate:2 Infiltration safety factor:1 Total Volume Infiltrated (ac-ft.):104.744 Total Volume Through Riser (ac-ft.):0 Total Volume Through Facility (ac-ft.):104.744 Percent Infiltrated:100 Total Precip Applied to Facility:10.196 Total Evap From Facility:4.179 Underdrain not used Discharge Structure Riser Height:3 ft. Riser Diameter:18 in. Element Outlets: Outlet 1 Outlet 2 Outlet Flows To: Bioretention Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.0806 0.0000 0.0000 0.0000 0.0714 0.0791 0.0008 0.0000 0.0000 0.1429 0.0777 0.0016 0.0000 0.0000 0.2143 0.0763 0.0025 0.0000 0.0002 0.2857 0.0749 0.0034 0.0000 0.0004 0.3571 0.0735 0.0043 0.0000 0.0008 0.4286 0.0721 0.0053 0.0000 0.0013 0.5000 0.0707 0.0063 0.0000 0.0020 0.5714 0.0693 0.0073 0.0000 0.0028 0.6429 0.0679 0.0083 0.0000 0.0029 0.7143 0.0665 0.0094 0.0000 0.0040 0.7857 0.0652 0.0106 0.0000 0.0053 0.8571 0.0638 0.0117 0.0000 0.0068 0.9286 0.0625 0.0129 0.0000 0.0086 1.0000 0.0612 0.0141 0.0000 0.0106 1.0714 0.0598 0.0154 0.0000 0.0124 1.1429 0.0585 0.0167 0.0000 0.0129 1.2143 0.0572 0.0180 0.0000 0.0154 1.2857 0.0559 0.0194 0.0000 0.0183 1.3571 0.0546 0.0208 0.0000 0.0214 1.4286 0.0533 0.0222 0.0000 0.0248 1.5000 0.0521 0.0237 0.0000 0.0285 1.5714 0.0508 0.0253 0.0000 0.0312 1.6429 0.0495 0.0269 0.0000 0.0325 1.7143 0.0483 0.0285 0.0000 0.0369 1.7857 0.0471 0.0302 0.0000 0.0413 1.8571 0.0458 0.0319 0.0000 0.0550 CK Yelm & Killion 10/31/2024 7:26:43 AM Page 12 1.9286 0.0446 0.0337 0.0000 0.0550 2.0000 0.0434 0.0354 0.0000 0.0550 2.0714 0.0422 0.0373 0.0000 0.0550 2.1429 0.0410 0.0391 0.0000 0.0550 2.2143 0.0398 0.0411 0.0000 0.0550 2.2857 0.0386 0.0430 0.0000 0.0550 2.3571 0.0374 0.0450 0.0000 0.0550 2.4286 0.0363 0.0470 0.0000 0.0550 2.5000 0.0351 0.0491 0.0000 0.0550 2.5714 0.0340 0.0512 0.0000 0.0550 2.6429 0.0328 0.0534 0.0000 0.0550 2.7143 0.0317 0.0556 0.0000 0.0550 2.7857 0.0306 0.0578 0.0000 0.0550 2.8571 0.0295 0.0601 0.0000 0.0550 2.9286 0.0284 0.0624 0.0000 0.0550 3.0000 0.0273 0.0648 0.0000 0.0550 Bioretention Surface Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)To Amended(cfs)Infilt(cfs) 3.0000 0.0806 0.0648 0.0000 0.0413 0.0000 3.0714 0.0820 0.0706 0.0000 0.0413 0.0000 3.1429 0.0835 0.0765 0.0000 0.0452 0.0000 3.2143 0.0850 0.0825 0.0000 0.0471 0.0000 3.2857 0.0864 0.0887 0.0000 0.0491 0.0000 3.3571 0.0879 0.0949 0.0000 0.0511 0.0000 3.4286 0.0894 0.1012 0.0000 0.0530 0.0000 3.5000 0.0909 0.1077 0.0000 0.0550 0.0000 3.5714 0.0924 0.1142 0.0000 0.0550 0.0000 3.6429 0.0939 0.1209 0.0000 0.0550 0.0000 3.7143 0.0955 0.1276 0.0000 0.0550 0.0000 3.7857 0.0970 0.1345 0.0000 0.0550 0.0000 3.8571 0.0985 0.1415 0.0000 0.0550 0.0000 3.9286 0.1001 0.1486 0.0000 0.0550 0.0000 4.0000 0.1017 0.1558 0.0000 0.0550 0.0000 4.0714 0.1032 0.1631 0.0000 0.0550 0.0000 4.1429 0.1048 0.1705 0.0000 0.0550 0.0000 4.2143 0.1064 0.1781 0.0000 0.0550 0.0000 4.2857 0.1080 0.1857 0.0000 0.0550 0.0000 4.3571 0.1096 0.1935 0.0000 0.0550 0.0000 4.4286 0.1112 0.2014 0.0000 0.0550 0.0000 4.5000 0.1128 0.2094 0.0000 0.0550 0.0000 4.5714 0.1144 0.2175 0.0000 0.0550 0.0000 4.6429 0.1161 0.2257 0.0000 0.0550 0.0000 4.7143 0.1177 0.2341 0.0000 0.0550 0.0000 4.7857 0.1194 0.2425 0.0000 0.0550 0.0000 4.8571 0.1210 0.2511 0.0000 0.0550 0.0000 4.9286 0.1227 0.2598 0.0000 0.0550 0.0000 5.0000 0.1244 0.2687 0.0000 0.0550 0.0000 5.0714 0.1261 0.2776 0.0000 0.0550 0.0000 5.1429 0.1278 0.2867 0.0000 0.0550 0.0000 5.2143 0.1295 0.2959 0.0000 0.0550 0.0000 5.2857 0.1312 0.3052 0.0000 0.0550 0.0000 5.3571 0.1329 0.3146 0.0000 0.0550 0.0000 5.4286 0.1346 0.3241 0.0000 0.0550 0.0000 5.5000 0.1364 0.3338 0.0000 0.0550 0.0000 5.5714 0.1381 0.3436 0.0000 0.0550 0.0000 5.6429 0.1399 0.3536 0.0000 0.0550 0.0000 5.7143 0.1416 0.3636 0.0000 0.0550 0.0000 CK Yelm & Killion 10/31/2024 7:26:43 AM Page 13 5.7857 0.1434 0.3738 0.0000 0.0550 0.0000 5.8571 0.1452 0.3841 0.0000 0.0550 0.0000 5.9286 0.1470 0.3945 0.0000 0.0550 0.0000 6.0000 0.1488 0.4051 0.0000 0.0550 0.0000 6.0714 0.1506 0.4158 0.3035 0.0550 0.0000 6.1429 0.1524 0.4266 0.8548 0.0550 0.0000 6.2143 0.1542 0.4375 1.5529 0.0550 0.0000 6.2857 0.1560 0.4486 2.3387 0.0550 0.0000 6.3571 0.1579 0.4598 3.1538 0.0550 0.0000 6.4286 0.1597 0.4712 3.9390 0.0550 0.0000 6.5000 0.1616 0.4827 4.6391 0.0550 0.0000 6.5000 0.1616 0.4827 5.2124 0.0550 0.0000 CK Yelm & Killion 10/31/2024 7:26:43 AM Page 14 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:2.28 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.99 Total Impervious Area:1.29 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.001766 5 year 0.003024 10 year 0.004174 25 year 0.006081 50 year 0.007897 100 year 0.010115 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.000302 5 year 0.001214 10 year 0.002553 25 year 0.005704 50 year 0.009651 100 year 0.015556 Annual Peaks CK Yelm & Killion 10/31/2024 7:27:28 AM Page 15 Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1956 0.013 0.002 1957 0.002 0.002 1958 0.002 0.000 1959 0.002 0.000 1960 0.002 0.001 1961 0.002 0.001 1962 0.002 0.000 1963 0.002 0.004 1964 0.002 0.001 1965 0.002 0.001 1966 0.002 0.000 1967 0.002 0.001 1968 0.002 0.000 1969 0.002 0.000 1970 0.002 0.000 1971 0.005 0.002 1972 0.038 0.005 1973 0.002 0.000 1974 0.002 0.000 1975 0.002 0.000 1976 0.002 0.001 1977 0.002 0.000 1978 0.002 0.001 1979 0.002 0.000 1980 0.002 0.000 1981 0.002 0.006 1982 0.002 0.000 1983 0.002 0.000 1984 0.002 0.000 1985 0.002 0.000 1986 0.002 0.001 1987 0.002 0.001 1988 0.002 0.000 1989 0.002 0.002 1990 0.002 0.000 1991 0.007 0.008 1992 0.002 0.000 1993 0.002 0.000 1994 0.001 0.000 1995 0.002 0.000 1996 0.002 0.002 1997 0.002 0.001 1998 0.002 0.004 1999 0.002 0.001 2000 0.001 0.000 2001 0.001 0.000 2002 0.001 0.000 2003 0.001 0.000 2004 0.002 0.000 2005 0.001 0.000 2006 0.001 0.000 2007 0.002 0.002 2008 0.001 0.000 2009 0.002 0.000 2010 0.002 0.000 2011 0.002 0.000 CK Yelm & Killion 10/31/2024 7:27:28 AM Page 16 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0380 0.0078 2 0.0128 0.0058 3 0.0065 0.0046 4 0.0051 0.0042 5 0.0018 0.0035 6 0.0018 0.0024 7 0.0018 0.0021 8 0.0018 0.0021 9 0.0018 0.0019 10 0.0018 0.0018 11 0.0018 0.0015 12 0.0018 0.0015 13 0.0018 0.0014 14 0.0018 0.0014 15 0.0018 0.0014 16 0.0018 0.0013 17 0.0018 0.0010 18 0.0018 0.0008 19 0.0018 0.0007 20 0.0018 0.0007 21 0.0018 0.0005 22 0.0018 0.0005 23 0.0018 0.0005 24 0.0018 0.0005 25 0.0018 0.0005 26 0.0018 0.0004 27 0.0018 0.0004 28 0.0018 0.0003 29 0.0018 0.0003 30 0.0018 0.0002 31 0.0018 0.0002 32 0.0018 0.0002 33 0.0018 0.0002 34 0.0018 0.0002 35 0.0018 0.0002 36 0.0018 0.0002 37 0.0018 0.0001 38 0.0018 0.0001 39 0.0018 0.0001 40 0.0018 0.0001 41 0.0018 0.0001 42 0.0017 0.0001 43 0.0017 0.0001 44 0.0017 0.0001 45 0.0017 0.0001 46 0.0017 0.0001 47 0.0017 0.0000 48 0.0016 0.0000 49 0.0015 0.0000 50 0.0014 0.0000 51 0.0014 0.0000 52 0.0013 0.0000 53 0.0011 0.0000 54 0.0008 0.0000 CK Yelm & Killion 10/31/2024 7:27:28 AM Page 17 55 0.0006 0.0000 56 0.0005 0.0000 CK Yelm & Killion 10/31/2024 7:27:28 AM Page 18 LID Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0001 25546 446 1 Pass 0.0001 24722 419 1 Pass 0.0002 23877 400 1 Pass 0.0002 23249 381 1 Pass 0.0002 22503 369 1 Pass 0.0002 21914 355 1 Pass 0.0002 21266 343 1 Pass 0.0002 20735 334 1 Pass 0.0002 20225 325 1 Pass 0.0002 19773 312 1 Pass 0.0002 19271 305 1 Pass 0.0002 18676 296 1 Pass 0.0002 18110 285 1 Pass 0.0002 17639 279 1 Pass 0.0002 17160 268 1 Pass 0.0003 16753 261 1 Pass 0.0003 16331 250 1 Pass 0.0003 16021 247 1 Pass 0.0003 15662 241 1 Pass 0.0003 15298 232 1 Pass 0.0003 14947 229 1 Pass 0.0003 14652 221 1 Pass 0.0003 14346 217 1 Pass 0.0003 14077 214 1 Pass 0.0003 13767 197 1 Pass 0.0003 13484 194 1 Pass 0.0003 13146 183 1 Pass 0.0003 12909 176 1 Pass 0.0004 12644 169 1 Pass 0.0004 12461 166 1 Pass 0.0004 12243 157 1 Pass 0.0004 12092 154 1 Pass 0.0004 11860 150 1 Pass 0.0004 11668 149 1 Pass 0.0004 11454 149 1 Pass 0.0004 11283 144 1 Pass 0.0004 11114 142 1 Pass 0.0004 10929 139 1 Pass 0.0004 10786 136 1 Pass 0.0004 10554 133 1 Pass 0.0004 10370 130 1 Pass 0.0004 10105 128 1 Pass 0.0005 9938 126 1 Pass 0.0005 9755 124 1 Pass 0.0005 9567 122 1 Pass 0.0005 9409 117 1 Pass 0.0005 9247 114 1 Pass 0.0005 9076 112 1 Pass 0.0005 8932 107 1 Pass 0.0005 8748 105 1 Pass 0.0005 8551 102 1 Pass 0.0005 8396 99 1 Pass 0.0005 8277 96 1 Pass CK Yelm & Killion 10/31/2024 7:27:28 AM Page 19 0.0005 8110 93 1 Pass 0.0005 8000 92 1 Pass 0.0006 7854 92 1 Pass 0.0006 7735 92 1 Pass 0.0006 7560 91 1 Pass 0.0006 7434 91 1 Pass 0.0006 7273 90 1 Pass 0.0006 7167 88 1 Pass 0.0006 7039 87 1 Pass 0.0006 6929 86 1 Pass 0.0006 6814 82 1 Pass 0.0006 6719 80 1 Pass 0.0006 6641 79 1 Pass 0.0006 6551 79 1 Pass 0.0006 6415 77 1 Pass 0.0007 6307 73 1 Pass 0.0007 6203 71 1 Pass 0.0007 6120 71 1 Pass 0.0007 6001 71 1 Pass 0.0007 5908 70 1 Pass 0.0007 5840 70 1 Pass 0.0007 5783 69 1 Pass 0.0007 5700 67 1 Pass 0.0007 5637 67 1 Pass 0.0007 5559 66 1 Pass 0.0007 5476 66 1 Pass 0.0007 5402 65 1 Pass 0.0007 5325 63 1 Pass 0.0007 5219 62 1 Pass 0.0008 5154 62 1 Pass 0.0008 5092 60 1 Pass 0.0008 5003 60 1 Pass 0.0008 4940 58 1 Pass 0.0008 4883 58 1 Pass 0.0008 4826 57 1 Pass 0.0008 4770 57 1 Pass 0.0008 4711 56 1 Pass 0.0008 4642 55 1 Pass 0.0008 4593 55 1 Pass 0.0008 4552 55 1 Pass 0.0008 4489 54 1 Pass 0.0008 4432 54 1 Pass 0.0009 4385 53 1 Pass 0.0009 4341 53 1 Pass 0.0009 4285 52 1 Pass 0.0009 4249 51 1 Pass 0.0009 4194 51 1 Pass CK Yelm & Killion 10/31/2024 7:27:40 AM Page 20 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0009 4194 51 1 Pass 0.0010 3619 49 1 Pass 0.0010 3106 43 1 Pass 0.0011 2641 39 1 Pass 0.0012 2233 35 1 Pass 0.0012 1879 32 1 Pass 0.0013 1608 29 1 Pass 0.0014 1355 27 1 Pass 0.0014 1163 25 2 Pass 0.0015 922 20 2 Pass 0.0016 667 18 2 Pass 0.0017 458 17 3 Pass 0.0017 268 16 5 Pass 0.0018 114 15 13 Pass 0.0019 22 15 68 Pass 0.0019 21 14 66 Pass 0.0020 21 14 66 Pass 0.0021 20 12 60 Pass 0.0022 19 11 57 Pass 0.0022 19 11 57 Pass 0.0023 18 10 55 Pass 0.0024 18 10 55 Pass 0.0024 18 9 50 Pass 0.0025 17 9 52 Pass 0.0026 16 8 50 Pass 0.0027 16 7 43 Pass 0.0027 16 7 43 Pass 0.0028 14 6 42 Pass 0.0029 13 6 46 Pass 0.0029 12 6 50 Pass 0.0030 12 6 50 Pass 0.0031 12 6 50 Pass 0.0032 11 6 54 Pass 0.0032 11 6 54 Pass 0.0033 11 6 54 Pass 0.0034 11 6 54 Pass 0.0034 10 6 60 Pass 0.0035 10 6 60 Pass 0.0036 10 4 40 Pass 0.0036 10 4 40 Pass 0.0037 10 4 40 Pass 0.0038 10 4 40 Pass 0.0039 9 4 44 Pass 0.0039 9 4 44 Pass 0.0040 9 4 44 Pass 0.0041 9 4 44 Pass 0.0041 9 4 44 Pass 0.0042 9 4 44 Pass 0.0043 9 3 33 Pass 0.0044 9 3 33 Pass 0.0044 9 3 33 Pass 0.0045 9 3 33 Pass 0.0046 9 3 33 Pass CK Yelm & Killion 10/31/2024 7:27:40 AM Page 21 0.0046 8 2 25 Pass 0.0047 8 2 25 Pass 0.0048 8 2 25 Pass 0.0049 8 2 25 Pass 0.0049 7 2 28 Pass 0.0050 7 2 28 Pass 0.0051 7 2 28 Pass 0.0051 6 2 33 Pass 0.0052 6 2 33 Pass 0.0053 6 2 33 Pass 0.0053 6 2 33 Pass 0.0054 6 2 33 Pass 0.0055 6 2 33 Pass 0.0056 6 2 33 Pass 0.0056 6 2 33 Pass 0.0057 6 2 33 Pass 0.0058 6 2 33 Pass 0.0058 6 1 16 Pass 0.0059 6 1 16 Pass 0.0060 6 1 16 Pass 0.0061 6 1 16 Pass 0.0061 6 1 16 Pass 0.0062 6 1 16 Pass 0.0063 6 1 16 Pass 0.0063 6 1 16 Pass 0.0064 5 1 20 Pass 0.0065 5 1 20 Pass 0.0066 4 1 25 Pass 0.0066 4 1 25 Pass 0.0067 4 1 25 Pass 0.0068 4 1 25 Pass 0.0068 4 1 25 Pass 0.0069 4 1 25 Pass 0.0070 4 1 25 Pass 0.0070 4 1 25 Pass 0.0071 4 1 25 Pass 0.0072 4 1 25 Pass 0.0073 4 1 25 Pass 0.0073 4 1 25 Pass 0.0074 4 1 25 Pass 0.0075 4 1 25 Pass 0.0075 4 1 25 Pass 0.0076 4 1 25 Pass 0.0077 4 1 25 Pass 0.0078 4 1 25 Pass 0.0078 4 0 0 Pass 0.0079 4 0 0 Pass CK Yelm & Killion 10/31/2024 7:27:40 AM Page 22 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0 acre-feet On-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Off-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. CK Yelm & Killion 10/31/2024 7:27:40 AM Page 23 LID Report CK Yelm & Killion 10/31/2024 7:27:54 AM Page 24 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. CK Yelm & Killion 10/31/2024 7:27:55 AM Page 25 Appendix Predeveloped Schematic CK Yelm & Killion 10/31/2024 7:27:56 AM Page 26 Mitigated Schematic CK Yelm & Killion 10/31/2024 7:27:57 AM Page 27 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1955 10 01 END 2011 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 CK Yelm & Killion.wdm MESSU 25 PreCK Yelm & Killion.MES 27 PreCK Yelm & Killion.L61 28 PreCK Yelm & Killion.L62 30 POCCK Yelm & Killion1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 1 A/B, Forest, Flat 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 1 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 1 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO CK Yelm & Killion 10/31/2024 7:27:57 AM Page 28 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 1 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 1 0 5 2 400 0.05 0.3 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 1 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 1 0.2 0.5 0.35 0 0.7 0.7 END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 1 0 0 0 0 3 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATE1 CK Yelm & Killion 10/31/2024 7:27:58 AM Page 29 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 1 2.28 COPY 501 12 PERLND 1 2.28 COPY 501 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 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 0.857 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 0.857 IMPLND 1 999 EXTNL PREC CK Yelm & Killion 10/31/2024 7:27:58 AM Page 30 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 END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 END MASS-LINK END RUN CK Yelm & Killion 10/31/2024 7:27:58 AM Page 31 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 CK Yelm & Killion.wdm MESSU 25 MitCK Yelm & Killion.MES 27 MitCK Yelm & Killion.L61 28 MitCK Yelm & Killion.L62 30 POCCK Yelm & Killion1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 7 IMPLND 1 IMPLND 4 IMPLND 8 RCHRES 1 RCHRES 2 RCHRES 3 RCHRES 4 COPY 1 COPY 501 COPY 601 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Surface retention 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 601 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 *** 7 A/B, Lawn, Flat 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** CK Yelm & Killion 10/31/2024 7:27:58 AM Page 32 # - # 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 4 ROOF TOPS/FLAT 1 1 1 27 0 8 SIDEWALKS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 4 0 0 1 0 0 0 8 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 4 1 9 4 0 0 4 0 0 0 1 9 8 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 CK Yelm & Killion 10/31/2024 7:27:58 AM Page 33 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 4 0 0 0 0 0 8 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 4 400 0.01 0.1 0.1 8 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 4 0 0 8 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 4 0 0 8 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 7 0.56 RCHRES 1 2 PERLND 7 0.56 RCHRES 1 3 IMPLND 1 0.45 RCHRES 1 5 IMPLND 4 0.125 RCHRES 1 5 IMPLND 8 0.085 RCHRES 1 5 Basin 2*** PERLND 7 0.39 RCHRES 3 2 PERLND 7 0.39 RCHRES 3 3 IMPLND 1 0.62 RCHRES 3 5 IMPLND 8 0.01 RCHRES 3 5 Basin 3*** PERLND 7 0.04 COPY 501 12 PERLND 7 0.04 COPY 601 12 PERLND 7 0.04 COPY 501 13 PERLND 7 0.04 COPY 601 13 ******Routing****** PERLND 7 0.56 COPY 1 12 IMPLND 1 0.45 COPY 1 15 IMPLND 4 0.125 COPY 1 15 IMPLND 8 0.085 COPY 1 15 PERLND 7 0.56 COPY 1 13 PERLND 7 0.39 COPY 1 12 IMPLND 1 0.62 COPY 1 15 IMPLND 8 0.01 COPY 1 15 PERLND 7 0.39 COPY 1 13 RCHRES 1 1 RCHRES 2 8 RCHRES 3 1 RCHRES 4 8 RCHRES 2 1 COPY 501 17 RCHRES 1 1 COPY 501 17 RCHRES 4 1 COPY 501 17 RCHRES 3 1 COPY 501 17 END SCHEMATIC CK Yelm & Killion 10/31/2024 7:27:58 AM Page 34 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 <-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 Surface retentio-008 2 1 1 1 28 0 1 2 Bioretention 1 2 1 1 1 28 0 1 3 Surface retentio-010 2 1 1 1 28 0 1 4 Bioretention 2 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 3 1 0 0 0 0 0 0 0 0 0 4 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 3 4 0 0 0 0 0 0 0 0 0 1 9 4 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 3 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 4 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** 1 1 0.01 0.0 0.0 0.0 0.0 2 2 0.02 0.0 0.0 0.0 0.0 3 3 0.01 0.0 0.0 0.0 0.0 4 4 0.02 0.0 0.0 0.0 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 3 0 4.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 4 0 4.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 CK Yelm & Killion 10/31/2024 7:27:58 AM Page 35 END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES FTABLE 2 43 5 Depth Area Volume Outflow1 Outflow2 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.074380 0.000000 0.000000 0.000000 0.071429 0.073027 0.000725 0.000000 0.000000 0.142857 0.071682 0.001480 0.000000 0.000000 0.214286 0.070345 0.002264 0.000000 0.000182 0.285714 0.069017 0.003077 0.000000 0.000404 0.357143 0.067697 0.003920 0.000000 0.000746 0.428571 0.066386 0.004793 0.000000 0.001225 0.500000 0.065083 0.005696 0.000000 0.001858 0.571429 0.063788 0.006630 0.000000 0.002519 0.642857 0.062502 0.007595 0.000000 0.002660 0.714286 0.061224 0.008590 0.000000 0.003645 0.785714 0.059955 0.009616 0.000000 0.004824 0.857143 0.058695 0.010675 0.000000 0.006210 0.928571 0.057442 0.011764 0.000000 0.007813 1.000000 0.056198 0.012886 0.000000 0.009644 1.071429 0.054963 0.014040 0.000000 0.011247 1.142857 0.053736 0.015226 0.000000 0.011713 1.214286 0.052517 0.016445 0.000000 0.014029 1.285714 0.051307 0.017697 0.000000 0.016600 1.357143 0.050105 0.018981 0.000000 0.019435 1.428571 0.048912 0.020300 0.000000 0.022541 1.500000 0.047727 0.021652 0.000000 0.025923 1.571429 0.046551 0.023084 0.000000 0.028405 1.642857 0.045383 0.024551 0.000000 0.029584 1.714286 0.044223 0.026055 0.000000 0.033517 1.785714 0.043072 0.027593 0.000000 0.037500 1.857143 0.041929 0.029168 0.000000 0.050000 1.928571 0.040795 0.030779 0.000000 0.050000 2.000000 0.039669 0.032427 0.000000 0.050000 2.071429 0.038552 0.034111 0.000000 0.050000 2.142857 0.037443 0.035832 0.000000 0.050000 2.214286 0.036343 0.037591 0.000000 0.050000 2.285714 0.035250 0.039387 0.000000 0.050000 2.357143 0.034167 0.041221 0.000000 0.050000 2.428571 0.033092 0.043093 0.000000 0.050000 2.500000 0.032025 0.045003 0.000000 0.050000 2.571429 0.030966 0.046951 0.000000 0.050000 2.642857 0.029917 0.048939 0.000000 0.050000 2.714286 0.028875 0.050965 0.000000 0.050000 2.785714 0.027842 0.053030 0.000000 0.050000 2.857143 0.026817 0.055135 0.000000 0.050000 2.928571 0.025801 0.057280 0.000000 0.050000 3.000000 0.024793 0.060498 0.000000 0.050000 END FTABLE 2 FTABLE 1 51 5 Depth Area Volume Outflow1 Outflow2 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.024793 0.000000 0.000000 0.000000 0.071429 0.075742 0.005362 0.000000 0.037500 0.142857 0.077112 0.010821 0.000000 0.041071 0.214286 0.078491 0.016378 0.000000 0.042857 0.285714 0.079879 0.022034 0.000000 0.044643 0.357143 0.081274 0.027789 0.000000 0.046429 0.428571 0.082678 0.033645 0.000000 0.048214 0.500000 0.084091 0.039601 0.000000 0.050000 0.571429 0.085512 0.045658 0.000000 0.050000 0.642857 0.086941 0.051817 0.000000 0.050000 0.714286 0.088379 0.058079 0.000000 0.050000 0.785714 0.089825 0.064443 0.000000 0.050000 CK Yelm & Killion 10/31/2024 7:27:58 AM Page 36 0.857143 0.091280 0.070911 0.000000 0.050000 0.928571 0.092743 0.077483 0.000000 0.050000 1.000000 0.094215 0.084160 0.000000 0.050000 1.071429 0.095695 0.090943 0.000000 0.050000 1.142857 0.097183 0.097831 0.000000 0.050000 1.214286 0.098680 0.104827 0.000000 0.050000 1.285714 0.100186 0.111929 0.000000 0.050000 1.357143 0.101699 0.119139 0.000000 0.050000 1.428571 0.103221 0.126458 0.000000 0.050000 1.500000 0.104752 0.133885 0.000000 0.050000 1.571429 0.106291 0.141423 0.000000 0.050000 1.642857 0.107839 0.149070 0.000000 0.050000 1.714286 0.109395 0.156828 0.000000 0.050000 1.785714 0.110959 0.164698 0.000000 0.050000 1.857143 0.112532 0.172680 0.000000 0.050000 1.928571 0.114113 0.180774 0.000000 0.050000 2.000000 0.115702 0.188982 0.000000 0.050000 2.071429 0.117301 0.197304 0.000000 0.050000 2.142857 0.118907 0.205740 0.000000 0.050000 2.214286 0.120522 0.214291 0.000000 0.050000 2.285714 0.122145 0.222957 0.000000 0.050000 2.357143 0.123777 0.231740 0.000000 0.050000 2.428571 0.125417 0.240640 0.000000 0.050000 2.500000 0.127066 0.249657 0.000000 0.050000 2.571429 0.128723 0.258793 0.000000 0.050000 2.642857 0.130389 0.268047 0.000000 0.050000 2.714286 0.132063 0.277420 0.000000 0.050000 2.785714 0.133745 0.286913 0.000000 0.050000 2.857143 0.135436 0.296527 0.000000 0.050000 2.928571 0.137135 0.306261 0.000000 0.050000 3.000000 0.138843 0.316118 0.000000 0.050000 3.071429 0.140559 0.326096 0.303494 0.050000 3.142857 0.142284 0.336198 0.854840 0.050000 3.214286 0.144017 0.346423 1.552922 0.050000 3.285714 0.145758 0.356772 2.338680 0.050000 3.357143 0.147508 0.367246 3.153809 0.050000 3.428571 0.149266 0.377845 3.938950 0.050000 3.500000 0.151033 0.388570 4.639092 0.050000 3.500000 0.151033 0.388570 5.212417 0.050000 END FTABLE 1 FTABLE 4 43 5 Depth Area Volume Outflow1 Outflow2 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.080579 0.000000 0.000000 0.000000 0.071429 0.079136 0.000798 0.000000 0.000000 0.142857 0.077703 0.001627 0.000000 0.000000 0.214286 0.076278 0.002489 0.000000 0.000201 0.285714 0.074861 0.003382 0.000000 0.000445 0.357143 0.073453 0.004307 0.000000 0.000820 0.428571 0.072053 0.005265 0.000000 0.001347 0.500000 0.070661 0.006256 0.000000 0.002044 0.571429 0.069278 0.007280 0.000000 0.002771 0.642857 0.067904 0.008337 0.000000 0.002926 0.714286 0.066537 0.009428 0.000000 0.004009 0.785714 0.065180 0.010552 0.000000 0.005306 0.857143 0.063830 0.011711 0.000000 0.006831 0.928571 0.062489 0.012903 0.000000 0.008595 1.000000 0.061157 0.014130 0.000000 0.010609 1.071429 0.059833 0.015392 0.000000 0.012372 1.142857 0.058517 0.016689 0.000000 0.012885 1.214286 0.057210 0.018020 0.000000 0.015432 1.285714 0.055912 0.019388 0.000000 0.018260 1.357143 0.054621 0.020791 0.000000 0.021379 1.428571 0.053340 0.022230 0.000000 0.024795 1.500000 0.052066 0.023705 0.000000 0.028515 1.571429 0.050801 0.025267 0.000000 0.031246 1.642857 0.049545 0.026867 0.000000 0.032542 1.714286 0.048297 0.028505 0.000000 0.036868 1.785714 0.047057 0.030182 0.000000 0.041250 CK Yelm & Killion 10/31/2024 7:27:58 AM Page 37 1.857143 0.045826 0.031897 0.000000 0.055000 1.928571 0.044603 0.033651 0.000000 0.055000 2.000000 0.043388 0.035445 0.000000 0.055000 2.071429 0.042182 0.037277 0.000000 0.055000 2.142857 0.040985 0.039149 0.000000 0.055000 2.214286 0.039796 0.041062 0.000000 0.055000 2.285714 0.038615 0.043014 0.000000 0.055000 2.357143 0.037443 0.045006 0.000000 0.055000 2.428571 0.036279 0.047040 0.000000 0.055000 2.500000 0.035124 0.049114 0.000000 0.055000 2.571429 0.033977 0.051229 0.000000 0.055000 2.642857 0.032839 0.053386 0.000000 0.055000 2.714286 0.031709 0.055584 0.000000 0.055000 2.785714 0.030587 0.057824 0.000000 0.055000 2.857143 0.029474 0.060106 0.000000 0.055000 2.928571 0.028369 0.062431 0.000000 0.055000 3.000000 0.027273 0.065934 0.000000 0.055000 END FTABLE 4 FTABLE 3 51 5 Depth Area Volume Outflow1 Outflow2 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.027273 0.000000 0.000000 0.000000 0.071429 0.082029 0.005807 0.000000 0.041250 0.142857 0.083488 0.011719 0.000000 0.045179 0.214286 0.084955 0.017735 0.000000 0.047143 0.285714 0.086431 0.023856 0.000000 0.049107 0.357143 0.087915 0.030082 0.000000 0.051071 0.428571 0.089408 0.036415 0.000000 0.053036 0.500000 0.090909 0.042855 0.000000 0.055000 0.571429 0.092419 0.049402 0.000000 0.055000 0.642857 0.093937 0.056058 0.000000 0.055000 0.714286 0.095463 0.062822 0.000000 0.055000 0.785714 0.096998 0.069696 0.000000 0.055000 0.857143 0.098541 0.076679 0.000000 0.055000 0.928571 0.100093 0.083773 0.000000 0.055000 1.000000 0.101653 0.090979 0.000000 0.055000 1.071429 0.103221 0.098296 0.000000 0.055000 1.142857 0.104798 0.105725 0.000000 0.055000 1.214286 0.106384 0.113267 0.000000 0.055000 1.285714 0.107978 0.120923 0.000000 0.055000 1.357143 0.109580 0.128693 0.000000 0.055000 1.428571 0.111191 0.136577 0.000000 0.055000 1.500000 0.112810 0.144578 0.000000 0.055000 1.571429 0.114438 0.152693 0.000000 0.055000 1.642857 0.116074 0.160926 0.000000 0.055000 1.714286 0.117718 0.169276 0.000000 0.055000 1.785714 0.119371 0.177743 0.000000 0.055000 1.857143 0.121032 0.186329 0.000000 0.055000 1.928571 0.122702 0.195034 0.000000 0.055000 2.000000 0.124380 0.203858 0.000000 0.055000 2.071429 0.126067 0.212803 0.000000 0.055000 2.142857 0.127762 0.221868 0.000000 0.055000 2.214286 0.129465 0.231055 0.000000 0.055000 2.285714 0.131177 0.240363 0.000000 0.055000 2.357143 0.132898 0.249795 0.000000 0.055000 2.428571 0.134626 0.259349 0.000000 0.055000 2.500000 0.136364 0.269027 0.000000 0.055000 2.571429 0.138109 0.278830 0.000000 0.055000 2.642857 0.139863 0.288757 0.000000 0.055000 2.714286 0.141626 0.298811 0.000000 0.055000 2.785714 0.143397 0.308990 0.000000 0.055000 2.857143 0.145176 0.319296 0.000000 0.055000 2.928571 0.146964 0.329730 0.000000 0.055000 3.000000 0.148760 0.340291 0.000000 0.055000 3.071429 0.150565 0.350982 0.303494 0.055000 3.142857 0.152378 0.361801 0.854840 0.055000 3.214286 0.154200 0.372750 1.552922 0.055000 3.285714 0.156030 0.383830 2.338680 0.055000 3.357143 0.157868 0.395040 3.153809 0.055000 CK Yelm & Killion 10/31/2024 7:27:58 AM Page 38 3.428571 0.159715 0.406383 3.938950 0.055000 3.500000 0.161570 0.417857 4.639092 0.055000 3.500000 0.161570 0.417857 5.212417 0.055000 END FTABLE 3 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 WDM 2 PREC ENGL 0.857 RCHRES 1 EXTNL PREC WDM 2 PREC ENGL 0.857 RCHRES 3 EXTNL PREC WDM 1 EVAP ENGL 0.5 RCHRES 1 EXTNL POTEV WDM 1 EVAP ENGL 0.76 RCHRES 2 EXTNL POTEV WDM 1 EVAP ENGL 0.5 RCHRES 3 EXTNL POTEV WDM 1 EVAP ENGL 0.76 RCHRES 4 EXTNL POTEV END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL COPY 601 OUTPUT MEAN 1 1 48.4 WDM 901 FLOW ENGL REPL RCHRES 2 HYDR RO 1 1 1 WDM 1000 FLOW ENGL REPL RCHRES 2 HYDR O 1 1 1 WDM 1001 FLOW ENGL REPL RCHRES 2 HYDR O 2 1 1 WDM 1002 FLOW ENGL REPL RCHRES 2 HYDR STAGE 1 1 1 WDM 1003 STAG ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1004 STAG ENGL REPL RCHRES 1 HYDR O 1 1 1 WDM 1005 FLOW ENGL REPL RCHRES 4 HYDR RO 1 1 1 WDM 1006 FLOW ENGL REPL RCHRES 4 HYDR O 1 1 1 WDM 1007 FLOW ENGL REPL RCHRES 4 HYDR O 2 1 1 WDM 1008 FLOW ENGL REPL RCHRES 4 HYDR STAGE 1 1 1 WDM 1009 STAG ENGL REPL RCHRES 3 HYDR STAGE 1 1 1 WDM 1010 STAG ENGL REPL RCHRES 3 HYDR O 1 1 1 WDM 1011 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 8 RCHRES OFLOW OVOL 2 RCHRES INFLOW IVOL END MASS-LINK 8 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 CK Yelm & Killion 10/31/2024 7:27:58 AM Page 39 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 MASS-LINK 17 RCHRES OFLOW OVOL 1 COPY INPUT MEAN END MASS-LINK 17 END MASS-LINK END RUN CK Yelm & Killion 10/31/2024 7:27:58 AM Page 40 Predeveloped HSPF Message File CK Yelm & Killion 10/31/2024 7:27:58 AM Page 41 Mitigated HSPF Message File CK Yelm & Killion 10/31/2024 7:27:58 AM Page 42 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 Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Appendix E: Conveyance Calculations Project:Date:Initials:TC Area (ac)Area (ac)Area (ac)Area (ac)Area (ac)A C ISR Basin A CB-01 0.38 0.07 0.00 0.00 0.00 0.45 0.78 0.85 Basin B CB-02 0.14 0.00 0.00 0.00 0.00 0.14 0.90 1.00 Basin B CB-03 0.08 0.00 0.00 0.00 0.00 0.08 0.90 1.00 Basin B CB-04 0.05 0.00 0.00 0.00 0.00 0.05 0.89 0.99 Total 0.66 0.07 0.00 0.00 0.00 0.73 0.83 0.90 Inlet Drainage Area Calculations for Rational Method Post Development Post-Development Conditions 10/02/24 Runoff Coefficients Land Cover Range Use -- -- General Impervious 0.75 - 0.95 Lawns 0.05 - 0.35 -- Runoff Coefficients Drainage Area General Impervious Lawns --- Area (sf)Area (sf)Area (sf)Area (sf)Area (sf) Runoff Coefficient Impervious Ratio Runoff Coefficient 0.90 Runoff Coefficient 0.15 Runoff Coefficient 0.00 Runoff Coefficient 0.00 Runoff Coefficient 0.00 Total Area 16,498 3,001 6,169 0 3,640 0 2,268 19 28,575 3,020 0 0 0 Project:Date:Initials:TC Pipe Characteristics Drainage Area Characteristics Material PVC/HDPE Area acres Manning's n 0.013 Rational Coefficient Pipe Diameter 8 in Rainfall Intensity in/hr 2 yr Slope (User)0.026 ft/ft in/hr 10 yr Length 125.9 ft in/hr 25 yr Upstrem Invert 349.22 ft in/hr 100 yr Downstream Invert 346 ft Slope (Calculated)0.026 ft/ft Full Flow Velocity 5.58 fps Flow Capacity 1.95 cfs 2 yr 10 yr 25 yr Actual Velocity 3.80 fps 100 yr Friction Loss 1.51 ft Pipe Drop 3.22 ft V10 2.6 ft/s m n Tc I 2 yr 3.820 0.466 5.000 1.804 10 yr 5.620 0.474 5.000 2.621 25 yr 6.630 0.477 5.000 3.077 100 yr 8.170 0.480 5.000 3.773 3.77 Pipe Capacity Calculations CB-01 TO BIORETENTION A 10/02/24 0.45 0.78 1.80 2.62 3.08 Intensity 100 yr pipe analysis Pipe 1 / Inlet 1 1.33 68% Peak Runoff Runoff/Capacity 33% 47% 55% 0.63 0.92 1.08 Project:Date:Initials:TC Pipe Characteristics Drainage Area Characteristics Material PVC/HDPE Area acres Manning's n 0.013 Rational Coefficient Pipe Diameter 8 in Rainfall Intensity in/hr 2 yr Slope (User)0.006 ft/ft in/hr 10 yr Length 81.076 ft in/hr 25 yr Upstrem Invert 348.76 ft in/hr 100 yr Downstream Invert 348.306 ft Slope (Calculated)0.006 ft/ft Full Flow Velocity 2.59 fps Flow Capacity 0.90 cfs 2 yr 10 yr 25 yr Actual Velocity 1.38 fps 100 yr Friction Loss 0.13 ft Pipe Drop 0.45 ft V10 1.0 ft/s m n Tc I 2 yr 3.820 0.466 5.000 1.804 10 yr 5.620 0.474 5.000 2.621 25 yr 6.630 0.477 5.000 3.077 100 yr 8.170 0.480 5.000 3.773 Pipe Capacity Calculations CB-02 TO CB-03 10/07/24 0.14 0.90 1.80 3.77 2.62 3.08 Pipe 1 / Inlet 1 Peak Runoff Runoff/Capacity 0.33 37% 0.23 25% Intensity 100 yr pipe analysis 0.39 43% 0.48 53% Project:Date:Initials:TC Pipe Characteristics Drainage Area Characteristics Material PVC/HDPE Area acres Manning's n 0.013 Rational Coefficient Pipe Diameter 8 in Rainfall Intensity in/hr 2 yr Slope (User)0.065 ft/ft in/hr 10 yr Length 13 ft in/hr 25 yr Upstrem Invert 347.779 ft in/hr 100 yr Downstream Invert 346.921 ft Slope (Calculated)0.065 ft/ft Full Flow Velocity 8.83 fps Flow Capacity 3.08 cfs 2 yr 10 yr 25 yr Actual Velocity 2.19 fps 100 yr Friction Loss 0.05 ft Pipe Drop 0.86 ft V10 1.5 ft/s m n Tc I 2 yr 3.820 0.466 5.000 1.804 10 yr 5.620 0.474 5.000 2.621 25 yr 6.630 0.477 5.000 3.077 100 yr 8.170 0.480 5.000 3.773 Intensity 0.53 17% 100 yr pipe analysis 0.62 20% 0.76 25% Pipe 1 / Inlet 1 Peak Runoff Runoff/Capacity 0.37 12% 0.23 0.90 1.80 3.77 2.62 3.08 Pipe Capacity Calculations CB-03 TO BIORETENTION 2 10/07/24 Project:Date:Initials:TC Pipe Characteristics Drainage Area Characteristics Material PVC/HDPE Area acres Manning's n 0.013 Rational Coefficient Pipe Diameter 6 in Rainfall Intensity in/hr 2 yr Slope (User)0.059 ft/ft in/hr 10 yr Length 75 ft in/hr 25 yr Upstrem Invert 350.13 ft in/hr 100 yr Downstream Invert 345.7 ft Slope (Calculated)0.059 ft/ft Full Flow Velocity 6.95 fps Flow Capacity 1.37 cfs 2 yr 10 yr 25 yr Actual Velocity 0.90 fps 100 yr Friction Loss 0.07 ft Pipe Drop 4.43 ft V10 0.6 ft/s m n Tc I 2 yr 3.820 0.466 5.000 1.804 10 yr 5.620 0.474 5.000 2.621 25 yr 6.630 0.477 5.000 3.077 100 yr 8.170 0.480 5.000 3.773 Intensity 0.12 9% 100 yr pipe analysis 0.14 11% 0.18 13% Pipe 1 / Inlet 1 Peak Runoff Runoff/Capacity 0.08 6% 0.05 0.89 1.80 3.77 2.62 3.08 Pipe Capacity Calculations CB-04 TO BIORETENTION 2 10/07/24 Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Appendix F: Geotechnical Report www.mooretwining.com PH: 559.268.7021 FX : 559.268.7126 2527 Fresno Street Fresno, CA 93721 GEOTECHNICAL ENGINEERING INVESTIGATION PROPOSED CIRCLE K STORE NORTHWEST CORNER OF YELM AVENUE AND KILLION ROAD YELM, WASHINGTON Project Number: G28867.01 For: Circle K Stores, Inc. 225 East Rincon St. Suite 100 Corona, California 92879 March 20, 2024 www.mooretwining.com PH: 559.268.7021 FX : 559.268.7126 2527 Fresno Street Fresno, CA 93721 March 20, 2024 G28867.01 Circle K Stores, Inc. c/o Sevan Multi-Site Solutions Ms. Christine Harris Laguna Hills, CA 92653 Subject:Geotechnical Engineering Investigation Proposed Circle K Store Northwest Corner of Yelm Avenue and Killion Road Yelm, Washington Dear Ms. Harris: We are pleased to submit this geotechnical engineering investigation report prepared for the proposed Circle K to be located at the northwest corner of Yelm Avenue and Killion Road in Yelm, Washington. The contents of this report include the purpose of the investigation, scope of services, background information, investigative procedures, our findings, evaluation, conclusions, and recommendations. It is recommended that Moore Twining Associates, Inc. (Moore Twining) be retained to review those portions of the plans and specifications that pertain to earthwork, pavements, and foundations to determine if they are consistent with our recommendations. This service is not a part of this current contractual agreement; however, the client should provide these documents for our review prior to their issuance for construction bidding purposes. We appreciate the opportunity to be of service to Circle K Stores, Inc. If you have any questions regarding this report, or if we can be of further assistance, please contact us at your convenience at (800) 268-7021. Sincerely, MOORE TWINING ASSOCIATES, INC. Alan Villegas Staff Engineer Geotechnical Engineering Division G28867.01 EXECUTIVE SUMMARY Moore Twining Associates, Inc. (Moore Twining) prepared this geotechnical engineering investigation report for the proposed Circle K store to be located on a 2.326-acre property at the northwest corner of Yelm Avenue and Killion Road in Yelm, Washington. The proposed Circle K development is planned to include a 4,253 square foot convenience store; a fuel island area covered by a canopy, and an underground fuel storage tank location. Appurtenant construction is anticipated to include concrete walkways, asphalt concrete and Portland cement concrete parking and drive areas, trash enclosure, underground utilities, and landscape areas. At the time of our field investigation, the site was undeveloped and was covered with tall native grasses and shrubs, and a majority of the site was covered with a dense growth of large, mature trees. Frontage improvements were noted along Yelm Avenue and Killion Road, including a concrete sidewalk and a landscaped strip with planted trees between the sidewalk and the edge of the roadways. As part of this investigation, seven (7) test pits were excavated at the site to depths ranging from about 7½ to about 9 feet below site grades (BSG) and two (2) borings were drilled to depths of about 25 feet and 50.3 feet BSG. The soils encountered generally consisted of a topsoil with organics and roots that visually classified as silty sand or poorly graded sand with silt, with varying amounts of gravel and traces of cobble extending to depths ranging from about 1½ feet to about 3 feet BSG. The topsoil was underlain by poorly graded gravels with some seams of poorly graded sands, and well graded gravels with varying amounts of fines, sands and cobble contents to the maximum depth explored of about 50.3 feet BSG. Varying amounts of cobble (rock greater than 3 inches in dimension) and some boulders (rock greater than 12 inches in diameter) were also observed at varying depths. In order to limit static settlements of the new Circle K store building to 1 inch total and ½ inch differential, the on-site soils should be over-excavated and compacted to a depth of at least 2 feet below preconstruction site grades in the building pad areas and to at least 1 foot below bottom of foundations, whichever is greater. Due to the high organic contents, the topsoils should be stripped and removed from the areas planned for the new improvements. Soils with more than 3 percent organics should not remain, nor be used as fill below the proposed improvements. In addition, large trees and shrubs are present within the site. In addition, root structures were noted within the near surface soils. As part of the site preparation, trees, shrubs, all vegetation, and all roots will need to be removed from the areas of the planned improvements. The subsurface soils encountered below the topsoils contained gravel, cobble and boulders. Due to the high cobble content and the presence of boulders, oversize material will need to be removed from the onsite soils prior to use as engineered fill for the project. In addition, some of the test pits exhibited caving. Thus, unstable excavation sidewalls should be anticipated as part of the project and measures to support the excavations should be anticipated as part of the proposed. This executive summary should not be used for design or construction and should be reviewed in conjunction with the attached report. G28867.01 TABLE OF CONTENTS Page 1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 1 2.0 PURPOSE AND SCOPE OF INVESTIGATION . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 1 22.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 1 2.2 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . 2 3.0 BACKGROUND INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . 3 3.1 Site Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 3 3.2 Site History and Previous Studies . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 3 3.3 Anticipated Construction . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 3 4.0 INVESTIGATIVE PROCEDURES . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 4 4.1 Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 4 4.2 Field Exploration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 4 4.2.1 Site Reconnaissance . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . 4 4.2.2 Drilling Test Borings . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . 4 4.2.3 Soil Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 5 4.3 Laboratory Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 5 5.0 FINDINGS AND RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 5 5.1 Site Geology and Seismic Hazards . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 5 5.2 Subsurface Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 6 5.3 Soil Engineering Properties . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . 6 5.4 Groundwater Conditions . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 7 6.0 EVALUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 7 6.1 Subsurface Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 7 6.2 Static Settlement and Bearing Capacity of Shallow Foundations . . . . . . . . . . . . . 8 6.3 Fault Rupture and Seismic Design Coefficients . . .. . . . . . . . . . . . . . . . . . . . . . . 8 6.4 Liquefaction and Seismic Settlement . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 9 6.5 Pavements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . 9 6.6 Soil Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 9 6.7 Sulfate Attack of Concrete . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 10 G28867.01 TABLE OF CONTENTS Page 7.0 CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8.0 RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 88.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 88.2 Site Grading and Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 88.3 Site Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 8.4 Engineered Fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8.5 Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 8.6 Slabs-on-Grade Within the Building Preparation Limits . . . . . . . . . . . . . . . . . . . 23 8.7 Exterior Concrete Flatwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 8.8 Asphaltic Concrete (AC) Pavements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 8.9 Portland Cement Concrete (PCC) Pavements . . . . . . . . . . . . . . . . . . . . . . . . . . .28 8.10 Underground Fuel Storage Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 8.11 Temporary Excavations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 8.12 Utility Trenches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 8.13 Corrosion Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 9.0 DESIGN CONSULTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 10.0 CONSTRUCTION MONITORING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 11.0 NOTIFICATION AND LIMITATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 APPENDICES APPENDIX A - Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1 APPENDIX B - Logs of Borings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1 APPENDIX C - Results of Laboratory Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1 APPENDIX D - Photographs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1 Drawing No. 1 - Site Location Map Drawing No. 2 - Test Boring/Pit Location Map - Proposed conditons Drawing No. 3 - Test Boring/Pit Location Map - Existing condiitons GEOTECHNICAL ENGINEERING INVESTIGATION PROPOSED CIRCLE K STORE YELM AVENUE AND KILLION ROAD YELM, WASHINGTON Project Number: G28867.01 1.0 INTRODUCTION This report presents the results of a geotechnical engineering investigation for the proposed Circle K store to be located at the northwest corner of Yelm Avenue and Killion Road in Yelm, Washington. Moore Twining Associates, Inc. (Moore Twining) was authorized by Circle K Stores, Inc. to perform this geotechnical engineering investigation. The contents of this report include the purpose of the investigation and the scope of services provided. The site history, previous studies, site description, and anticipated construction are discussed. In addition, a description of the investigative procedures used and the subsequent findings obtained are presented. Finally, the report provides an evaluation of the findings, general conclusions, and related recommendations. The report appendices contain the drawings (Appendix A), the logs of borings (Appendix B), the results of laboratory tests (Appendix C) and site photographs (Appendix D). 2.0 PURPOSE AND SCOPE OF INVESTIGATION 2.1 Purpose: The purpose of the investigation was to conduct a field exploration and a laboratory testing program, evaluate the data collected during the field and laboratory portions of the investigation, and provide the following: 2.1.1 Evaluation of the near surface soils within the zone of influence of the proposed foundations and pavements with regard to the anticipated foundation and vehicle traffic loads; 2.1.2 Recommendations for mapped seismic coefficients and earthquake spectral response acceleration values in accordance with the 2021 International Building Code; 2.1.3 Geotechnical parameters for use in design of foundations and slabs-on-grade, (e.g., soil bearing capacity and settlement); Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 2 2.1.4 Recommendations for site preparation including placement, moisture conditioning, and compaction of engineered fill soils; 2.1.5 Recommendations for the design and construction of new asphalt concrete (AC) and Portland cement concrete (PCC) pavements; 2.1.6 Recommendations for temporary excavations and trench backfill; 2.1.7 Evaluation of the potential for liquefaction; and 2.1.8 Conclusions regarding soil corrosion potential. This report is provided specifically for the proposed Circle K store referenced in the Anticipated Construction section of this report. This investigation did not include a geologic/seismic hazards evaluation, flood plain investigation, compaction tests, environmental investigation, or environmental audit. 2.2 Scope: Our revised proposal, dated December 14, 2023, outlined the scope of our services. The actions undertaken during the investigation are summarized as follows. 2.2.1 The site plans labeled CSP 8.0W, 8.0A, 8.0T, and 8.0 dated November 6, 2023, prepared by Greenberg Farrow, were reviewed. 2.2.2 A visual site reconnaissance and subsurface exploration were conducted. 2.2.3 Satellite images of the site between the years 1990 and 2023 from online sources, were reviewed. 2.2.4 Laboratory tests were conducted to determine selected physical and engineering properties of the subsurface soils. 2.2.5 Ms. Christine Harris (Sevan Multi-Site Solutions) was consulted during the investigation. 2.2.6 The data obtained from the investigation were evaluated to develop an understanding of the subsurface soil conditions and the engineering properties of the subsurface soils. 2.2.7 This report was prepared to present the purpose and scope, background information, field exploration procedures, findings, evaluation, conclusions, and recommendations. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 3 3.0 BACKGROUND INFORMATION The existing site features, site history, previous studies, and the anticipated construction are summarized in the following subsections. 3.1 Site Description: Based on the referenced site plans, the site is a 2.326-acre property located at the northwest corner of Yelm Avenue and Killion Road in Yelm, Washington. A site location map is presented on Drawing No. 1 in Appendix A of this report. The site is located at 46.948867 degrees latitude and -122.617429 degrees longitude. USGS topographic map data indicates the site has an elevation of about 350 feet above mean seal level. The site is relatively flat with a gentle gradient to the southwest. The site is bound to the north by a paved private roadway, to the south and west by Yelm Avenue, and to the east by Killion Road. Photographs showing the existing site conditions are included in Appendix D of this report. At the time of our field investigation, the site was undeveloped and was covered with tall native grasses and shrubs, and a majority of the site was covered with a dense growth of large, mature trees. Some of the trees had trunks larger than 2 to 3 feet in diameter. Frontage improvements were noted along Yelm Avenue and Killion Road, including a concrete sidewalk and a landscaped strip with planted trees between the sidewalk and the edge of the roadways. 3.2 Site History and Previous Studies: Aerial images dating from 1990 to 2023 were reviewed. A June 1990 aerial image shows a former structure along the south edge of the site. The 2002 image shows the structure had been removed. The 2009 image shows the frontage improvements along Yelm Avenue and Killion Road had been constructed. Based on the images from 2009 to 2023 and the conditions observed at the time of our field exploration in February of 2024, the site has remained in a similar condition to that described in Section 3.1 of this report since about 2009. No reports of previous geotechnical engineering, geological, compaction testing, or environmental studies conducted for this site were provided for review during this investigation. If available, these reports should be provided to our firm for review and consideration for this project. 3.3 Anticipated Construction: The site plan provided to our firm indicates the Circle K development will include a 4,253 square foot convenience store, a fuel island area covered by a canopy, and an underground fuel storage tank. Appurtenant construction is anticipated to include concrete walkways, asphaltic concrete and Portland cement concrete parking and drive areas, underground utilities, a trash enclosure, and landscape areas. It is anticipated that the proposed Circle K structure will consist of a single story building with concrete masonry unit or wood frame construction and concrete slab-on-grade floors. It is anticipated that the proposed building will be supported on shallow spread foundation systems. The fuel island canopy could be supported on either cast-in-drilled-hole shafts or shallow spread foundations. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 4 For the purpose of this report, maximum column loads of about 30 kips and maximum perimeter wall loads of 4.2 kips per linear foot were assumed. The actual design foundation loads should be provided to Moore Twining when available. In the event that the maximum foundation loads exceed those assumed for design, the recommendations of this report may not be applicable and may need to be revised. The underground storage tanks planned for this project are to be located in the south portion of the site. It is our understanding that excavation to about 20 feet below final grade will be required to install the underground fuel storage tanks. Based on the relatively flat to gently sloping grade, cuts and fills on the order of about 1 to about 2 feet are anticipated to achieve level pad grades and provide positive site drainage. 4.0 INVESTIGATIVE PROCEDURES The field exploration and laboratory testing programs conducted for this investigation are summarized in the following subsections. 4.1 Site Reconnaissance: The site reconnaissance conducted on February 8, 2024 consisted of walking the site and noting visible surface features. The features noted are described in the background information section of this report. 4.2 Field Exploration: The field exploration included a site reconnaissance, clearing of dense brush and small trees to provide equipment access to the boring locations, excavation of backhoe test pits, drilling test borings, conducting standard penetration tests and soil sampling. Prior to conducting the exploration, the site was marked for Washington Utility Notification Center for member utilities to mark out the locations of their utilities. 4.2.1 Test Pits: On February 8, 2024, seven (7) test pits were excavated to depths ranging from about 7½ to about 9 feet below site grades (BSG). The test pits were excavated with a mini-excavator equipped with a 24-inch wide bucket. Four (4) of the seven (7) test pits experienced caving below a depth of about 6 feet due to the cohesionless, poorly graded nature of the soils encountered. The approximate locations of the test pits are depicted on Drawing No. 1 in Appendix A. Bulk samples were obtained during the excavation. After the test pits were logged, the excavated soils were used to loosely backfill the excavations. Thus, some settlement of the backfill soils should be anticipated. 4.2.2 Drilling Test Borings: The test borings were drilled in the building and underground fuel tank areas to supplement the data obtained from the backhoe test pits. The approximate locations of the borings are depicted on Drawing No. 1 in Appendix A. The depths of the test borings were selected based on the size of the structures, type of construction, estimated depths of influence of the anticipated foundation loads, and the subsurface soil conditions encountered. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 5 Two (2) test borings were drilled with a track-mounted sonic drill rig equipped with 6-inch diameter casing and a 5-inch diameter core barrel to depths of about 25 and 50.3 feet BSG. The test borings were drilled under the direction of a Moore Twining staff engineer. The field soil classification was in accordance with the Unified Soil Classification System and consisted of particle size, color, and other distinguishing features of the soil. The presence and elevation of free water, if any, in the borings were noted and recorded during drilling and immediately following completion of the borings. The test borings were backfilled with material excavated during the drilling operations. 4.2.3 Soil Sampling: Standard penetration tests were conducted in the test borings, and bulk soil samples were obtained. The standard penetration resistance, N-value, is defined as the number of blows required to drive a standard split barrel sampler into the soil. The standard split barrel sampler has a 2-inch O.D. and a 1d-inch inside diameter (I.D.). The sampler is driven by a 140-pound weight free falling 30 inches. The sampler is lowered to the bottom of the bore hole and set by driving it an initial 6 inches. It is then driven an additional 12 inches and the number of blows required to advance the sampler the additional 12 inches is recorded as the N-value. Soil samples obtained were taken to Moore Twining's laboratory for classification and testing. 4.3 Laboratory Testing: The laboratory testing was programmed to determine selected physical and engineering properties of samples obtained during the investigation. The results of laboratory tests are summarized in Appendix C. These data, along with the field observations, were used to prepare the final test boring logs in Appendix B. 5.0 FINDINGS AND RESULTS The findings and results of the research, field exploration and laboratory testing are summarized in the following subsections. 5.1 Site Geology and Seismic Hazards: The United States Department of Agriculture Natural Resources Conservation Service (NRCS) soil survey maps describe the soils at the site as Spanaway gravelly sandy loam. The soil survey describes the soils as “gravelly sandy loam” to depths of about 15 inches, underlain by “extremely gravelly sandy loam to very gravelly sandy loam” to a depth of about 20 inches, and “extremely gravelly sand and extremely gravelly loamy sand” to a depth of about 5 feet BSG. The soil survey data lists a range of 5 to 10 percent cobbles in the upper 10 inches and from 10 to 25 percent cobbles from a depth of about 20 inches to 60 inches. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 6 The USGS Geologic Map of Upper Eocene to Holocene and Related Rocks in the Cascade Range, Washington, indicates the site is covered with glacial deposits (Qg), including glacial outwash and related glaciofluvial and glaciolacustrine deposits. The Washington State Department of Natural Resources Geologic Survey on-line geographic information system data (GIS) information indicates the site is not mapped within nor near an area that requires an investigation of fault rupture hazard. Additionally, the Thurston County Planning Department Liquefaction Hazard Map indicates the project site is located in an area with a very low liquefaction susceptibility. 5.2 Subsurface Profile: The soils encountered in the backhoe pits and borings conducted for this investigation generally consisted of a topsoil with organics and roots that visually classified as silty sand or poorly graded sand with silt, with varying amounts of gravel and traces of cobble extending to depths ranging from about 1½ feet to about 3 feet BSG. The topsoil was underlain by poorly graded gravels with some seams of poorly graded sands, and well graded gravels with varying amounts of fines, sands and cobble contents to the maximum depth explored of about 50.3 feet BSG. Varying amounts of cobble (rock greater than 3 inches in dimension) and some boulders (rock greater than 12 inches in diameter) were also observed at varying depths. Refer to Section 5.1 of this report for a description of the cobbles listed in the NRCS soil survey. The foregoing is a general summary of the soil conditions encountered in the test borings drilled for this investigation. Detailed descriptions of the soils encountered at each test pit and boring location are presented in the logs of borings and test pits in Appendix B. The stratification lines in the logs represent the approximate boundary soil types; the actual in-situ transition may be gradual. 5.3 Soil Engineering Properties: The following is a description of the soil engineering properties as determined from our field exploration and laboratory testing. Topsoil: The near surface silty sand and poorly graded sand soils extending to depths of about 1½ to 3 feet are described in this report as topsoil due to the high organic contents. A loss on ignition test conducted on a near surface silty sand soil sample indicated 8.9 percent organics. The moisture content of the samples tested ranged from about 8.2 to 19.5 percent. Poorly Graded Sands with Silt: The poorly graded sands encountered below the topsoil were described as having varying amounts of gravel and cobble. The moisture content of the samples tested ranged from about 7.1 to about 7.5 percent. Well and Poorly Graded Gravel: The well and poorly graded gravels encountered were described as medium dense to very dense, as determined by standard penetration resistance, N-values, ranging from 27 to over 50 blows per foot. The moisture content of the samples tested ranged from about 3.5 to about 7.1 percent. These soils were observed to contain varying amounts of fine to large cobble; and boulders. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 7 Chemical Tests: Chemical tests performed on a near surface soil sample indicated a pH value of 6.2; a minimum resistivity value of 61,000 ohm-centimeters; non-detected percent by weight concentrations of chlorides (reporting limit of 0.0040 percent by weight); and non-detected percent by weight concentrations of sulfates (reporting limit of 0.0040 percent by weight). 5.4 Groundwater Conditions: Groundwater was encountered in test boring B-1 at a depth of about 30 feet BSG at the time of our March, 2024 field exploration. A well report for a water well installed near the project site was reviewed. The report indicates a groundwater depth of about 35 feet in April of 2010. It should be recognized, however, that groundwater elevations fluctuate with time, since they are dependent upon seasonal precipitation, irrigation, land use, and climatic conditions as well as other factors. Therefore, water level observations at the time of the field investigation may vary from those encountered both during the construction phase and the design life of the project. The evaluation of such factors was beyond the scope of this investigation and report. 6.0 EVALUATION The data and methodology used to develop conclusions and recommendations for project design and preparation of construction specifications are summarized in the following subsections. The evaluation was based upon the subsurface soil conditions encountered during this investigation and our understanding of the proposed construction. The conclusions obtained from the results of our evaluations are described in the Conclusions section of this report. 6.1 Subsurface Conditions: The subsurface investigation encountered topsoils with a high organic content to depths ranging from about 1½ to about 3 feet BSG. Due to the high organic contents, the topsoils should be stripped and removed from the areas planned for the new improvements. Soils with more than 3 percent organics should not remain below proposed improvements. In addition, large trees and shrubs are present within the site. In addition, root structures were noted within the near surface soils. As part of the site preparation, trees, shrubs, all vegetation, and all roots will need to be removed from the areas of the planned improvements. The subsurface soils encountered below the topsoils generally consisted of poorly graded sand with silt, with varying amounts of gravel and traces of cobble, poorly graded gravels with some seams of poorly graded sands, and well graded gravels with varying amounts of fines, sand and cobble. Fine to large cobble material and some boulders (greater than 12 inches in diameter) were also encountered. Due to the high cobble content and the presence of boulders, oversize material will need to be removed from the onsite soils prior to use as engineered fill for the project. In addition, some of the test pits exhibited caving. Thus, unstable excavation sidewalls should be anticipated as part of the project and measures to support the excavations should be anticipated as part of the construction. In addition, due to the presence of cobbles and boulders, a spread foundation is recommended for the canopy foundations (instead of drilled pier foundations). Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 8 6.2 Static Settlement and Bearing Capacity of Shallow Foundations: The potential for excessive total and differential static settlement of foundations and slabs-on-grade is a geotechnical concern that was evaluated for this project. The increases in effective stress to the underlying soils which can occur from new foundations and structures, placement of fill, withdrawal of groundwater, etc. can cause vertical deformation of the soils, which can result in damage to the overlying structures and improvements. The differential component of the settlement is often the most damaging. In addition, the allowable bearing pressures of the soils supporting the foundations were evaluated for shear and punching type failure of the soils resulting from the imposed foundation loads. The near surface topsoils with high organic content encountered in the test pits and borings drilled are not considered suitable for direct support of the proposed foundations, slabs-on-grade, pavements or fill soils. In order to reduce the potential for excessive static settlement of foundations and to limit the total and differential static settlement of foundations to 1 inch total and ½ inch differential in 40 feet, this report recommends supporting new foundations for the Circle K store on onsite soil which is processed to remove oversize material and then compacted as engineered fill; or imported engineered fill soils that extend to a depth of 1 foot below the proposed foundations. A net allowable soil bearing pressure of 2,500 pounds per square foot, for dead-plus-live loads, may be used for design of foundations supported on subgrade soils prepared as recommended in this report. The net allowable soil bearing pressure is the additional contact pressure at the base of the foundations caused by the structure. The weight of the soil backfill and weight of the footing may be neglected. The net allowable soil bearing pressure presented was selected using the Terzaghi bearing capacity equations for foundations considering a minimum factor of safety of 3.0 and based on the anticipated static settlements noted in this report. Thornton County reports that foundations should be designed using a frost depth of 12 inches. However, this report recommends that perimeter foundations should extend at least 18 inches below the lowest adjacent finished grade. A structural engineer experienced in foundation and slab-on-grade design should determine the thickness, reinforcement, design details and concrete specifications for the proposed building foundations and slabs-on-grade based on the anticipated settlements estimated in this report. 6.3 Faulting and Seismic Design Coefficients: Based on the Washington Division of Geology Faults and Earthquakes map, the nearest active faults are located about 18 miles to the northwest of the site, and about 30 miles west of the site. Thus, the potential for surface fault rupture is considered low. It is our understanding that the 2021 IBC will be used for structural design. Based on the 2021 IBC, the site is classified as a stiff soil (SD), Site Class D. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 9 6.4 Liquefaction and Seismic Settlement: Liquefaction and seismic settlement are conditions that can occur under seismic shaking from earthquake events. Liquefaction describes a phenomenon in which a saturated, cohesionless soil loses strength during an earthquake as a result of induced shearing strains. Lateral and vertical movements of the soil mass, combined with loss of bearing usually results. Fine, well sorted, loose sand, shallow groundwater conditions, higher intensity earthquakes, and particularly long duration of ground shaking are the requisite conditions for liquefaction. The Thurston County Planning Department Liquefaction Hazard Map indicates the project site is located in a very low liquefaction susceptibility area. Based on the dense nature of the gravels and granular soils encountered, liquefaction is not considered a significant hazard at this site. 6.5 Pavements: Recommendations for asphalt concrete (AC) pavement structural sections and Portland Cement Concrete (PCC) pavement sections are presented in the "Recommendations" section of this report. The analyses were based on a range of traffic loading conditions from auto and truck traffic. The appropriate paving section should be determined by the project civil engineer or applicable design professional based on the actual vehicle loading (traffic index) values. If traffic loading is anticipated to be greater than assumed, the pavement sections should be re-evaluated. It should be noted that if pavements are constructed prior to the construction of the structures, the additional construction truck traffic should be considered in the selection of the traffic index value. If more frequent or heavier traffic is anticipated and higher Traffic Index values are needed, Moore Twining should be contacted to provide additional pavement section designs. R-value tests were conducted on near surface soil samples, which indicated R-value results of 75 and 78. Based on the results of the testing and our experience with similar sites, an R-value of 50 was used to design the pavement sections. A modulus of subgrade reaction, K-value, for the PCC pavement section, considering a minimum 6-inch layer of aggregate base material (minimum R- value of 78), of 230 psi/in at the top of the aggregate base was used for design. 6.6 Soil Corrosion: The risk of corrosion of construction materials relates to the potential for soil-induced chemical reaction. Corrosion is a naturally occurring process whereby the surface of a metallic structure is oxidized or reduced to a corrosion product such as iron oxide (i.e., rust). The metallic surface is attacked through the migration of ions and loses its original strength by the thinning of the member. Soils make up a complex environment for potential metallic corrosion. The corrosion potential of a soil depends on numerous factors including soil resistivity, texture, acidity, field moisture and chemical concentrations. In order to evaluate the potential for corrosion of metallic objects in contact with the onsite soils, chemical testing of soil samples was performed by Moore Twining as Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 10 part of this report. The test results are included in Appendix C of this report. Conclusions regarding the corrosion potential of the soils tested are included in the Conclusions section of this report based on the National Association of Corrosion Engineers (NACE) corrosion severity ratings listed in the Table No. 1 below. Table No. 1 Soil Resistivity and Corrosion Potential Ratings Soil Resistivity (ohm cm) Corrosion Potential Rating >20,000 Essentially non-corrosive 10,000 - 20,000 Mildly corrosive 5,000 - 10,000 Moderately corrosive 3,000 - 5,000 Corrosive 1,000 - 3,000 Highly corrosive <1,000 Extremely corrosive The results of soil sample analyses indicate that the near-surface soils exhibit an “Essentially non- corrosive” corrosion potential to buried metal objects. If piping or concrete are placed in contact with imported soils, these soils should be analyzed to evaluate the corrosion potential of these soils. If the manufacturers or suppliers cannot determine if materials are compatible with the soil corrosion conditions, a professional consultant, i.e., a corrosion engineer, with experience in corrosion protection should be consulted to provide design parameters. Moore Twining does not provide corrosion engineering services. 6.7 Sulfate Attack of Concrete: Degradation of concrete in contact with soils due to sulfate attack involves complex physical and chemical processes. When sulfate attack occurs, these processes can reduce the durability of concrete by altering the chemical and microstructural nature of the cement paste. Sulfate attack is dependent on a variety of conditions including concrete quality, exposure to sulfates in soil, groundwater and environmental factors. The standard practice for geotechnical engineers in evaluation of the soils anticipated to be in contact with structural concrete is to perform laboratory testing to determine the concentrations of sulfates present in the soils. The test results are then compared with the exposure classes in Table 19.3.1.1 of ACI 318 to provide guidelines for concrete exposed to soils containing sulfates. It should be noted that other exposure conditions such as the presence of seawater, groundwater with elevated concentrations of dissolved sulfates, or materials other than soils can result in sulfate exposure categories to concrete that are higher than the concentrations of sulfate in soil. The design engineer will need to determine whether other potential sources of sulfate exposure need to be considered other than exposure to sulfates in soil. The sulfate exposure classes for soils from Table 19.3.1.1 are summarized in the below table. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 11 Table No. 2 ACI Exposure Categories for Water Soluble Sulfate in Soils Sulfate Exposure Class (per ACI 318) Water Soluble Sulfate in Soil (Percent by Mass) S0 Less than 0.10 Percent S1 0.10 to Less than 0.20 Percent S2 0.20 to Less than or Equal to 2.00 Percent S3 Greater than 2.00 Percent Common methods used to resist the potential for degradation of concrete due to sulfate attack from soils include, but are not limited to, the use of sulfate-resisting cements, air-entrainment and reduced water to cement ratios. The laboratory test results for sulfates are included in Appendix C of this report. Conclusions regarding the sulfate test results are included in the Conclusions section of this report. 7.0 CONCLUSIONS Based on the data collected during the field and laboratory investigations, our geotechnical experience in the vicinity of the project site, and our understanding of the anticipated construction, the following general conclusions are presented. 7.1 The site is considered suitable for the proposed construction with regard to support of the proposed improvements, provided the recommendations contained in this report are followed. It should be noted that the recommended design consultation and observation of clearing, and earthwork activities by Moore Twining are integral to this conclusion. 7.2 The soils encountered generally consisted of a topsoil with organics and roots that visually classified as silty sand or poorly graded sand with silt, with varying amounts of gravel and traces of cobble extending to depths ranging from about 1½ feet to about 3 feet BSG. The topsoil was underlain by poorly graded gravels with some seams of poorly graded sands, and well graded gravels with varying amounts of fines, sands and cobble contents to the maximum depth explored of about 50.3 feet BSG. Varying amounts of cobble (rock greater than 3 inches in dimension) and some boulders (rock greater than 12 inches in diameter) were also observed at varying depths. The soil survey data lists a range of 5 to 10 percent cobbles in the upper 10 inches and from 10 to 25 percent cobbles from a depth of about 20 inches to 60 inches. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 12 7.3 Groundwater was encountered in one of the test borings drilled at the time of our March 2024 field exploration at depth of about 30 feet BSG. 7.4 The subsurface investigation encountered topsoils with a high organic content to depths ranging from about 1½ to about 3 feet BSG. A sample of the topsoil indicated 8.9 percent organics. Roots were generally noted throughout the topsoil. Due to the high organic contents, the topsoils should be stripped and removed from the areas planned for the new improvements. Soils with more than 3 percent organics should not remain, nor be used as fill below the planned improvements. 7.5 In order to limit static settlements for the new Circle K store building to 1 inch total and ½ inch differential in 40 feet, the foundations should be supported on engineered fill as recommended in this report. 7.6 The subsurface soils encountered below the topsoils generally consisted of poorly graded sand with silt, with varying amounts of gravel and traces of cobble, poorly graded gravels with some seams of poorly graded sands, and well graded gravels with varying amounts of fines, sand and cobble. Fine to large cobble material and some boulders (greater than 12 inches in diameter) were also encountered. Due to the high cobble content and the presence of boulders, oversize material will need to be removed from the onsite soils prior to use as engineered fill for the project. 7.7 The potential for fault rupture at the site is considered low. 7.8 Chemical testing of soil samples indicated the soils exhibit an “essentially non- corrosive” potential for metallic corrosion. 7.9 Based on Table 19.3.1.1 - Exposure categories and classes from Chapter 19 of ACI 318, the sulfate concentration from chemical testing of soil samples falls in the S0 classification (less than 0.10 percent by weight) for concrete. 8.0 RECOMMENDATIONS Based on the evaluation of the field and laboratory data and our geotechnical experience, the following recommendations are presented for use in the project design and construction. This report should be considered in its entirety. When applying the recommendations for design, the background information, procedures used, findings, evaluation, and conclusions should be considered. The recommended design consultation and construction monitoring by a qualified geotechnical testing agency are integral to the proper application of the recommendations. The contractor is required to comply with the requirements and recommendations presented in this report. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 13 Where the requirements of a governing agency, utility agency or pipe manufacturer differ from the recommendations of this report, the more stringent recommendations should be applied to the project. 8.1 General 8.1.1 Moore Twining should be retained to review the final grading plans and foundation plans before the plans are released for bidding purposes so that any relevant recommendations can be presented. 8.1.2 When the actual foundation loads are known, this information should be provided to Moore Twining for review to confirm the recommendations for site preparation are appropriate for the project. In the event the foundation loads are different than assumed, the recommendations in this report may need to be revised. 8.1.3 If wet or unsuitable soils are encountered, additional time and dry weather may be required to reduce the moisture of the wet soils to a moisture content that will achieve proper placement and compaction for a stable engineered fill. 8.1.4 Cobble materials and rock fragments larger than 3 inches in smallest dimension (oversized materials) and some boulders (rock larger than 12 inches in dimension) should be anticipated during excavation. Oversized materials larger than 6inches in diameter will not be suitable for use in engineered fill. These materials may be required to be off-hauled from the site, or if allowed by Circle K, materials with rock greater than 6 inches in diameter may be placed in pavement areas and final backfill of utility trenches. 8.1.5 Based on the site plan, excavation for the underground fuel tanks will be in close proximity to the foundations for the fuel canopy. Since the underground fuel storage tanks will be mostly covered with pea gravel backfill that is encapsulated with a filter fabric, the contractor needs to consider these conditions in planning the excavation for the underground fuel tanks and the footings for the fuel canopy. This report recommends pea gravel backfill not extend closer than 8 feet horizontally from the edge of the fuel canopy foundations. Refer to Section 8.10 of this report. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 14 8.1.6 A preconstruction meeting including, as a minimum, the owner, general contractor, earthwork contractor, foundation and paving subcontractors, and the qualified geotechnical engineering testing firm should be scheduled by the general contractor at least one week prior to the start of clearing and grubbing. The purpose of the meeting should be to discuss critical project requirements and scheduling. 8.1.7 The contractor(s) bidding on this project should determine if the information included in the construction documents are sufficient for accurate bid purposes. If the data are not sufficient, the contractor should notify the Owner in writing prior to bidding the project if sufficient data is not available to accurately bid the project. The contractor shall describe in detail the issues that are not sufficient to submit an accurate bid. 8.2 Site Grading and Drainage 8.2.1 It is critical to develop and maintain site grades which will drain surface and roof runoff away from foundations and floor slabs - both during and after construction. Adjacent exterior finished grades should be sloped a minimum of five (5) percent for a distance of at least ten (10) feet away from the structures, or as necessary to preclude ponding of water adjacent to foundations, whichever is more stringent. Adjacent exterior grades which are paved should be sloped at least two (2) percent away from the foundations. 8.2.2 It is recommended that landscape planted areas, etc. not be placed adjacent to the building foundations and/or interior slabs-on-grade. Trees should be setback from the proposed structures at least ten (10) feet or a distance equal to the anticipated drip line radius of the mature tree. For example, if a tree has an anticipated drip-line diameter of thirty (30) feet, the tree should be planted at least fifteen (15) feet away (radius) from proposed or existing buildings. 8.2.3 Landscaping after construction should direct rainfall and irrigation runoff away from the structures and should establish positive drainage of water away from the structures. Care should be taken to maintain a leak-free sprinkler system. 8.2.4 Landscape and planter areas should be irrigated using low flow irrigation (such as drip, bubblers or mist type emitters). The use of plants with low water requirements are recommended. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 15 8.2.5 Rain gutters and roof drains should be provided, and connected directly to the site storm drain system. As an alternative, the roof drains should extend a minimum of five (5) feet away from the structures and the resulting runoff directed away from the structures at a minimum of two (2) percent. 8.3 Site Preparation 8.3.1 Stripping should be conducted in all areas to remove surface vegetation, root systems and topsoils. The organic topsoils were encountered to depths ranging from about 1½ to about 3 feet BSG. The depth of stripping should be sufficiently deep to remove all topsoils, root systems and organics. 8.3.2 All trees, shrubs and vegetation in the areas proposed for development should be removed in their entirety. All roots larger than one-quarter (¼) of an inch in diameter and any accumulation of organic matter that will result in an organic content more than three (3) percent by weight, should be removed and not used as engineered fill. It has been our experience that the roots from larger trees may generally extend to depths ranging from about three (3) to five (5) feet. In addition, the areas occupied by trees/tree roots should be excavated to a minimum depth of twelve (12) inches below the excavations required to remove the tree, root ball, and roots. After the removal of all organics and soils which are disturbed from the tree and root removal activity and approval of the bottom of the excavation, the bottom of the excavation should be scarified to a minimum depth of eight (8) inches and compacted as engineered fill prior to backfilling operations. If grinding operations are conducted on the site, these areas need to be cleaned of all organic matter and not used as engineered fill. Tree root removal operations and site preparation related to tree removal should be observed by a qualified geotechnical engineering testing firm. 8.3.3 As described in this report, seven (7) test pits were excavated to depths of about 7½ to 9 feet BSG. Drawing No. 2 in Appendix A of this report shown the approximate location of the test pits. The boring logs in appendix B of this report indicate the depth of each test pit. Each pit was about 4 feet wide and about 10 feet long. The test pits were loose backfilled. As part of the site preparation, the areas of the test pits should be over-excavated and backfilled with engineered fill in accordance with the recommendations provided in this report. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 16 8.3.4 After stripping, tree and root removal, and removal of topsoils and organics, the building pad area for the proposed Circle K store and over-build zones should be over-excavated to the depth required to removed all disturbed soils during root removals (mature tree roots anticipated to require excavation to depths of 3 to 5 feet), to a minimum of 1 foot below the bottom of footings, and a minimum of 4 feet below preconstruction site grades, whichever requires the deeper excavation. The horizontal limits of over-excavation should include the footprint of the building, all foundations, all concrete walkways adjacent to the building, and a minimum of 5 feet beyond these features, whichever is greater. Upon review of the contractor’s survey data (regarding the vertical and horizontal limits of the over-excavation) and approval of the over-excavation by the qualified geotechnical engineering testing firm, the bottom of the excavation should be scarified to a depth of 8 inches, moisture conditioned, and compacted as engineered fill. 8.3.5 It is recommended that extra care be taken by the contractor to ensure that the horizontal and vertical extent of the over-excavation and compaction conform to the site preparation recommendations presented in this report. The horizontal limits of over-excavation for the building pad for the proposed Circle K store should be depicted on the project plans. The contractor should verify in writing to the owner and qualified geotechnical engineering testing firm that the horizontal and vertical over-excavation limits were completed in conformance with the recommendations of this report, the project plans, and the specifications (the most stringent applies). It is recommended that this verification be performed by a licensed surveyor. The verification should be provided in writing and consist of a survey showing the horizontal and vertical limits of the over-excavation for the building pad as defined in this report. This verification should be provided prior to requesting pad certification from the qualified geotechnical engineering testing firm or excavating for foundations. 8.3.6 Final grading shall produce a building pad ready to receive a slab-on-grade which is smooth, planar, and resistant to rutting. Both the finished pad (before the aggregate base is placed) and the aggregate base section shall not depress more than one-half (½) inch under the wheels of a fully loaded concrete truck. If depressions more than one-half (½) inch occur, the contractor shall perform remedial grading to achieve this requirement at no cost to the Owner. The proof-rolling with a loaded concrete truck or equivalent shall be scheduled by the contractor and observed by the qualified geotechnical engineering testing firm. This observation shall be documented in writing by the qualified geotechnical engineering testing firm. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 17 8.3.7 After stripping, tree and root removal, and removal of topsoils and organics, the fuel canopy footings should be over-excavated to the depth required to removed all disturbed soils from the root removals (mature tree roots anticipated to require excavation to depths of 3 to 5 feet), and to a minimum of 1 foot below the bottom of the foundations, whichever requires the deeper excavation. The horizontal limits of over-excavation should extend a minimum of 3 feet beyond the edges of the foundations. Upon approval of the over-excavation by the qualified geotechnical engineering testing firm, the bottom of the excavation should be scarified to a depth of 8 inches, moisture conditioned, and compacted as engineered fill. 8.3.8 After stripping, tree and root removal, and removal of topsoils and organics, areas to receive miscellaneous lightly loaded foundations, such as site walls, retaining walls or screen walls for trash enclosures, should be over-excavated to the depth required to removed all disturbed soils from the root removals (mature tree roots anticipated to require excavation to depths of 3 to 5 feet), and to a minimum of 6 inches below the bottom of the foundations, whichever requires the deeper excavation. The over-excavation for retaining walls/screen walls should extend to at least 3 feet beyond the edges of the foundations. Upon approval, the bottom of the over-excavation should be scarified to a depth of at least 8 inches, moisture conditioned and compacted as engineered fill. 8.3.9 After stripping, tree and root removal, and removal of topsoils and organics, areas to receive new pavements, exterior slabs on grade outside the building pad preparation limits and areas to receive fill outside the building pad preparation limits should be over-excavated to the depth required to removed all disturbed soils from the root removals (mature tree roots anticipated to require excavation to depths of 3 to 5 feet), and to a depth of 12 inches below the bottom of the new aggregate base section, whichever requires the deeper excavation. The exposed surface after over-excavation should be scarified to a minimum depth of 8 inches, moisture conditioned to between optimum and three (3) percent above optimum moisture content and compacted as engineered fill. The limits of excavation and scarification for pavement areas and exterior slabs should extend at least 3 feet beyond the edge of these improvements or up to improvements to remain, whichever occurs first. The upper 12 inches of the subgrade soils beneath the pavement areas should be compacted to at least 95 percent of the maximum dry density as determined by ASTM Test Method D1557. 8.3.10 The qualified geotechnical engineering testing firm should observe the bottoms of all areas of over-excavation and observe and conduct in-place density tests during placement of engineered fill as grading progresses. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 18 8.3.11 All fill required to bring the site to final grades should be placed as engineered fill. In addition, all native soils over-excavated should be compacted as engineered fill. 8.3.12 The contractor should locate all on-site water wells (if any). All wells scheduled for demolition should be abandoned per federal, state and local requirements. The contractor should obtain an abandonment permit from the local environmental health department, and issue certificates of destruction to the owner and qualified geotechnical engineering testing firm upon completion. At a minimum, wells in building and foundation areas (and within 5 feet of building perimeters) should have their casings removed to a depth of at least 8 feet below preconstruction site grades or finished pad grades, whichever is deeper. In parking lot or landscape areas, the casings should be removed to a depth of at least 5 feet below site grades or finished grades. The wells should be capped with concrete and the resulting excavations should be backfilled as engineered fill. 8.3.13 The moisture content and density of the compacted soils should be maintained until the placement of concrete. If soft or unstable soils are encountered during excavation or compaction operations, our firm should be notified so the soils conditions can be examined and additional recommendations provided to address the pliant areas. 8.4 Engineered Fill 8.4.1 Interior and exterior concrete slabs on grade within the building pad preparation limits (including attached walkways) should be supported on a minimum of 4 inches of non-recycled aggregate base over engineered fill soils consisting of onsite soils or import granular fill materials. Exterior concrete slabs-on-grade outside the building pad preparation limits should be supported on a minimum of 4 inches of aggregate base over compacted subgrade soils. The on-site near surface soils encountered are predominantly gravels with varying amounts of cobble, and some boulders. Due to the oversize coarse gravel, cobbles and boulders, the onsite materials will need to be processed to meet the particle size requirements for engineered fill (including trench backfill) for this project. The onsite soils may be used as engineered fill, provided the soils have a plasticity index less than 15, are conditioned/dried to a suitable moisture content, the soils are free of organics (less than 3 percent by weight), the soils can be processed to a maximum particle size of 3 inches and a minimum of 70 percent passing the 3/4 inch sieve, are free of debris and are properly aerated/moisture conditioned to achieve the recommendations of this report. If the onsite materials cannot be processed to achieve the specified gradation, imported granular fill materials meeting the recommendations of Section 8.4.3 of this report should be used. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 19 8.4.2 The compactability of the native or import soils is dependent upon the moisture contents, subgrade conditions, degree of mixing, type of equipment, as well as other factors. The evaluation of such factors was beyond the scope of this report; therefore, it is recommended that they be evaluated by the contractor during preparation of bids and construction of the project. 8.4.3 Import fill soil should be non-expansive and granular in nature with the following acceptance criteria recommended. Percent Passing 3-Inch Sieve 100 Percent Passing 3/4 inch Sieve 70 - 100 Percent Passing No. 4 Sieve 60 - 100 Percent Passing No. 200 Sieve 5 - 20 Plasticity Index Less than 15 Organics Less than 3 percent by weight Sulfates < 0.05 percent by weight Resistivity > 10,000 ohms-cm R-value Minimum 50* * only in pavement areas Prior to being transported to the site, the import material shall be certified by the contractor and the supplier (to the satisfaction of the Owner) that the soils do not contain any environmental contaminates regulated by local, state or federal agencies having jurisdiction. In addition, the qualified geotechnical engineering testing firm should be requested to sample and test the material to determine compliance with the above geotechnical criteria. Contractors should provide a minimum of 7 working days to complete the testing. After approval of the contractor’s submittal regarding environmental requirements, the import fill material shall also be tested and approved by the qualified geotechnical engineering testing firm for the geotechnical requirements. The contractor shall allow a minimum of seven (7) working days for each import source to be tested by the qualified geotechnical engineering testing firm for compliance with the geotechnical characteristics specified in this report. 8.4.4 Onsite soils and imported, non-expansive engineered fill soils should be placed in loose lifts approximately 8 inches thick or less, moisture conditioned to within optimum to three (3) percent above optimum moisture content and compacted to at least 92 percent of the maximum dry density as determined by ASTM Test Method D1557, with exception that the upper 12 inches of the pavement subgrade soil should be compacted to at least 95 percent of the maximum dry density as determined by ASTM Test Method D1557. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 20 8.4.5 Utility trench backfill should be placed in 8 inch lifts, moisture conditioned and compacted as engineered fill in accordance with the recommendations included in Section 8.4.4 of this report. 8.4.6 In-place density tests should be conducted in accordance with ASTM D6938 (nuclear methods) at a minimum frequency of at least: Table No. 3 Area Minimum Test Frequency Under Building Slab on Ground 1 test per 2,500 square feet per lift, but not less than 2 tests per lift Fuel Canopy Foundations 1 test per footing per lift Mass Fills or Pavement Subgrade 1 test per 5,000 square feet per lift, but not less than 2 tests per lift Walkways 1 test per 50 linear feet per lift Utility Pipe and Structures Backfill 1 test per 100 linear feet of trench per compacted lift 8.4.7 Open graded gravel and rock material such as crushed rock should not be used as backfill including trench backfill. In the event gravel or rock is required by a regulatory agency for use as backfill, all open graded materials shall be fully encased in a geotextile filter fabric, such as Mirafi 140N, to prevent migration of fine grained soils into the porous material. Gravel and rock cannot be used without the written approval of the Owner. If used, crushed rock should be placed in thin (less than 8 inches) lifts and densified with a minimum of three (3) passes using a vibratory compactor. 8.4.8 Aggregate base shall comply with the State of Washington Department of Transportation requirements for Crushed Surfacing Material in accordance with the current edition of the Standard Specifications. Aggregate base used below the new interior concrete slabs on grade shall not contain recycled asphaltic concrete. Aggregate base for new exterior slabs-on-grade outside the building pad preparation limits and below pavements shall comply with State of Washington Department of Transportation requirements for Crushed Surfacing Material (aggregate base), modified to allow up to 100 percent of recycled materials. Aggregate base shall be compacted to a minimum relative Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 21 compaction of 95 percent based on ASTM D1557. Prior to importing the aggregate base material, the contractor should submit documentation demonstrating that the material meets all requirements for the applicable aggregate base. Documentation should be provided to the Owner, Architect and qualified geotechnical engineering testing firm and reviewed and approved prior to delivery of the aggregate base to the site. Base materials shall have negligible sulfate content with less than 0.1 percent soluble concentration. 8.5 Foundations 8.5.1 Spread and continuous footings supported on the subgrade soils prepared as recommended in this report (engineered fill) may be designed for a maximum net allowable soil bearing pressure of 2,500 pounds per square foot for dead- plus-live loads. This value may be increased by one-third for short duration wind or seismic loads. The weight of the footing and the soil backfill may be ignored in design. The building pad should be prepared in accordance with the recommendations included in the “Site Preparation” section of this report. 8.5.2 All footings should have a minimum width of 18 inches, regardless of load. All footings should be supported at a minimum depth of 18 inches below the lowest adjacent grade, or to the depth required to extend below the frost depth, whichever is deeper. 8.5.3 The foundations should be designed and reinforced for the anticipated settlements and for temperature and shrinkage effects. A structural engineer experienced in foundation design should recommend the thickness, design details and concrete specifications for the foundations based on: 1) a total static settlement of 1 inch, and 2) a differential static settlement and heave of ½ inch in 40 feet. 8.5.4 The foundations should be continuous around the perimeter of the structure to reduce moisture migration beneath the structure. Continuous perimeter foundations should be extended through doorways and/or openings that are not needed for support of loads. 8.5.5 The following seismic factors were developed using online data obtained from the Seismic Design Maps tool provided by the Structural Engineers Association of California (https://seismicmaps.org/) based upon a latitude of 46.948821 degrees and a longitude of -122.617891. The reported values are based upon the 2021 International Building Code and were not determined Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 22 based upon a ground motion hazard analysis. If a ground motion hazard analysis is required based upon the Seismic Design Category or structural detailing of the proposed structure(s), the following values will need to be updated with seismic factors determined by a ground motion hazard analysis. The designer should determine whether a ground motion hazard analysis is required for the project. If required, Moore Twining should be notified and requested to conduct the additional analysis and develop updated seismic factors for the project. Seismic Factor Site Class D (Stiff Soil) Maximum Considered Earthquake (geometric mean) peak ground acceleration adjusted for site effects (PGAM) 0.565g Mapped Maximum Considered Earthquake (geometric mean) peak ground acceleration (PGA) 0.514g Spectral Response At Short Period (0.2 Second), Ss 1.294 Spectral Response At 1-Second Period, S1 0.468 Site Coefficient (based on Spectral Response At Short Period), Fa 1.0 Site Coefficient (based on spectral response at 1- second period) Fv See note Maximum considered earthquake spectral response acceleration for short period, SMS 1.294 Maximum considered earthquake spectral response acceleration at 1 second, SM1 See note Five percent damped design spectral response accelerations for short period, SDS 0.863 Five percent damped design spectral response accelerations at 1-second period, SD1 See note Note: Requires ground motion hazard analysis per ASCE Section 21.2 (ASCE 7-16, Section 11.4.8), unless an Exception of Section 11.4.8 of ASCE 7-16 is applicable for the project design. *The above data is subject to the disclaimers listed in the website https://seismicmaps.org/ Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 23 8.5.6 The moisture contents of the footing excavations should be maintained at least optimum moisture content and in a stable condition by the contractor until placement of concrete. If the excavations are allowed to dry, conditioning and remedial measures should be conducted to establish the minimum recommended moisture contents and relative compaction. 8.5.7 Foundation excavations should be observed and approved by the qualified geotechnical engineering testing firm prior to the placement of steel reinforcement and concrete. 8.5.8 The bottom surface area of concrete footings or concrete slabs in direct contact with engineered fill can be used to resist lateral loads. An allowable coefficient of friction of 0.40 can be used for design. In areas where slabs are underlain by a synthetic moisture barrier, an allowable coefficient of friction of 0.10 can be used for design. 8.5.9 The allowable passive resistance of the native soils and engineered fill may be assumed to be equal to the pressure developed by a fluid with a density of 300 pounds per cubic foot for level soil conditions. The upper 12 inches of subgrade soils in landscape areas should be neglected in determining the total passive resistance. 8.5.10 Structural loads for lightly loaded (less than 1.5 kips per lineal foot) miscellaneous foundations (such as screen walls for the proposed trash enclosures) may be supported engineered fills prepared in accordance with the recommendations included in the Site Preparation section of this report. The lightly loaded foundations should extend to a minimum depth of 18 inches below the lowest adjacent grade and a minimum width of 12 inches, regardless of load. Footings for miscellaneous lightly loaded foundations may be designed for a maximum net allowable soil bearing pressure of 1,500 pounds per square foot for dead-plus-live loads. These values may be increased by one-third for short duration wind or seismic loads. 8.6 Interior Slabs-on-Grade 8.6.1 Interior slabs-on-grade and all concrete walkways adjacent to the building should be constructed over 4 inches of non-recycled aggregate base over engineered fill extending to the depth recommended below foundations in the Site Preparation section of this report. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 24 8.6.2 The recommendations provided herein are intended only for the design of interior concrete slabs-on-grade and their proposed uses, which do not include construction traffic (i.e., cranes, cement mixers, and rock trucks, etc.). The building contractor should assess the slab section and determine its adequacy to support any proposed construction traffic. 8.6.3 The slabs and underlying subgrade should be constructed in accordance with current American Concrete Institute (ACI) standards. 8.6.4 A vapor retarder should be placed below interior building slabs where moisture could permeate into the interior and create problems. Refer to the American Concrete Institute’s Guide to Concrete Floor and Slab Construction (ACI 302.1R) for selection and installation of moisture vapor retarders. It is recommended that a Stegowrap 15 vapor retarder be used where moisture could permeate into the interior and create problems, such as where flooring or floor slab applications will contain moisture sensitive materials (or other slab applications or uses). The vapor retarder should overlay the compacted 4 inch layer of aggregate base. It should be noted that placing the PCC slab directly on the vapor retarder may increase the potential for cracking and curling; however, ACI recommends the placement of the vapor retarding membrane directly below the slab unless a watertight roofing system is in place prior to slab construction to reduce the amount vapor emission through the slab-on-grade. It is recommended that the slab be moist cured for a minimum of 7 days to reduce the potential for excessive cracking. The underslab membrane should have a high puncture resistance (minimum of approximately 2,400 grams of puncture resistance), high abrasion resistance, rot resistant, and mildew resistant. It is recommended that the membrane be selected in accordance with the current ASTM C 755, Standard Practice For Selection of Vapor Retarder For Thermal Insulation and conform to the current ASTM E 1745 Plastic Water Vapor Retarders Used in Contact with Soil or Granular Fill under Concrete Slabs and ASTM E 154 Standard Test Methods for Water Vapor Retarders Used in Contact with Earth Under Concrete Slabs, on Waters, or as Ground Cover. It is recommended that the vapor barrier installation conform to the current ACI Manual of Concrete Practice, Guide for Concrete Floor and Slab Construction (302.1R), Addendum, Vapor Retarder Location and current ASTM E 1643, Standard Practice for Installation of Water Vapor Retarders Used In Contact with Earth or Granular Fill Under Concrete Slabs. In addition, it is recommended that the manufacturer of floor covering, floor covering adhesive or other slab material applications be consulted to determine if the manufacturers have Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 25 additional recommendations regarding the design and construction of the slab-on-grade, testing of the slab-on-grade, slab preparation, application of the adhesive, installation of the floor covering and maintenance requirements. It should be noted that the recommendations presented in this report are not intended to achieve a specific vapor emission rate. 8.6.5 The membrane should be installed so that there are no holes or uncovered areas. All seams should be overlapped and sealed with the manufacturer approved tape continuous at the laps so they are vapor tight. All perimeter edges of the membrane, such as pipe penetrations, interior and exterior footings, joints, etc., should be caulked per manufacturer’s recommendations. 8.6.6 Tears or punctures that may occur in the membrane should be repaired prior to placement of concrete per manufacturer’s recommendations. Once repaired, the membrane should be inspected by the contractor and the owner to verify adequate compliance with manufacture’s recommendations. 8.6.7 Additional measures to reduce moisture migration should be implemented for floors that will receive moisture sensitive coverings. These include: 1) constructing a less pervious concrete floor slab by maintaining a water- cement ratio of 0.52 or less in the concrete for slabs-on-grade, 2) ensuring that all seams and utility protrusions are sealed with tape to create a "water tight" moisture barrier, 3) placing concrete walkways or pavements adjacent to the structures, 4) providing adequate drainage away from the structures, 5) moist cure the slabs for at least 7 days, and 6) locating lawns, irrigated landscape areas, and flower beds away from the structures. 8.6.8 The contractor shall test the moisture vapor transmission through the slab, the pH, internal relative humidity, etc., at a frequency and method as specified by the flooring manufacturer or as required by the plans and specifications, whichever is most stringent. The results of vapor transmission tests, pH tests, internal relative humidity tests, ambient building conditions, etc. should be within floor manufacturer’s and adhesive manufacturer’s specifications at the time the floor is placed. It is recommended that the floor manufacturer and subcontractor review and approve the test data prior to floor covering installation. 8.6.9 To reduce the potential for damaging slabs during construction the following recommendations are presented: 1) design for a differential slab movement of ½ inch relative to interior columns; and 2) the construction equipment which will operate on slabs or pavements should be evaluated by the contractor prior to loading the slab. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 26 8.6.10 Backfill the zone above the top of footings at interior column locations, building perimeters, and below the bottom of slabs with an approved backfill as recommended herein for the area below interior slabs-on-grade. This procedure should provide more uniform support for the slabs which may reduce the potential for cracking. 8.7 Exterior Concrete Flatwork The following recommendations for exterior concrete flatwork are intended for pedestrian uses. The recommendations provided below are not intended for use for slabs subjected to vehicular or forklift traffic, rather lightly loaded sidewalks, curbs, and planters. 8.7.1 As noted in the Site Preparation section of this report, the exterior slabs-on- grade should be supported on a minimum of 4 inches of aggregate base (compacted to a minimum of 95 percent relative compaction) over compared subgrade prepared as recommended in this report. 8.7.2 The moisture content of the prepared subgrade soils should be verified to be between optimum and three (3) percent above optimum moisture content just prior to placement of the aggregate base section. 8.7.3 The concrete slabs-on-grade outside the building should be designed with thickened edges which extend to the bottom of the aggregate base, or deeper as determined by the designer. This should reduce the potential for infiltration of water into the non-expansive section below these slabs. 8.7.4 Since exterior sidewalks, curbs, etc. are typically constructed at the end of the construction process, the moisture conditioning conducted during earthwork can revert to natural dry conditions. Placing aggregate base materials and/or concrete walks and finish work over dry or slightly moist subgrade should be avoided. It is recommended that the general contractor notify the qualified geotechnical engineering testing firm to conduct in-place moisture and density tests prior to placing aggregate base and concrete flatwork. Written test results indicating passing density and moisture tests should be in the general contractor’s possession prior to placing concrete for exterior flatwork. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 27 8.8 Asphalt Concrete (AC) Pavements 8.8.1 The subgrade soils for asphalt concrete pavements should be over-excavated and compacted as recommended in the “Site Preparation” section of the recommendations in this report. As part of the final preparation, the upper 12 inches of the subgrade soils should be moisture conditioned and compacted to a minimum of 95 percent of the maximum dry density determined in accordance with ASTM D 1557. 8.8.2 The following pavement sections were designed using the AASHTO flexible pavement design method. The design utilized an R-value of 50, a design life of 20 years, and traffic loading ranging from Equivalent Single Axle Load (ESAL) of up to 10,900 to more frequent traffic using an ESAL of up to 410,420. The R-value of the subgrade soils should be verified by the qualified geotechnical engineering testing agency before placing the aggregate surface coarse. It should be noted that if pavements are constructed prior to construction of the buildings, the traffic index value should account for construction traffic. The actual ESAL traffic values applicable to the site should be determined by the project civil engineer. Table No. 4 Two-Layer Asphalt Concrete Pavements ESAL ADTT AC thickness, inches ASC thickness, inches Compacted Subgrade 10,900 1 3.0 6.0 12.0 47,300 2 3.5 6.0 12.0 164,000 8 4.0 6.0 12.0 410,420 24 4.5 7.0 12.0 ESAL - Equivalent single 18 kip axle load AC -Asphalt Concrete compacted as recommended in this report ASC - Aggregate Surface Course and compacted to at least 95 percent relative compaction (ASTM D1557) Subgrade - Subgrade soils compacted to at least 95 percent relative compaction (ASTM D1557) 8.8.3 The curbs where pavements meet irrigated landscape areas or uncovered open areas should be extended to the bottom of the aggregate base section. This should reduce the potential for subgrade moisture from irrigation and runoff from migrating into the base section and reducing the life of the pavements. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 28 8.8.4 If actual pavement subgrade materials are significantly different from those tested for this study due to unanticipated grading or soil importing, the pavement sections should be re-evaluated for the changed subgrade conditions. 8.8.5 If the paved areas are to be used during construction, or if the type and frequency of traffic are greater than specified, the pavement sections thicknesses should be increased for the anticipated additional traffic. 8.8.6 Pavement section design assumes that proper maintenance, such as sealing and repair of localized distress, will be performed on an as needed basis for longevity and safety. 8.8.7 Pavement materials and construction method should conform to the applicable State of Washington Standard Specification Requirements. 8.8.8 The asphaltic concrete, including the joint density, should be compacted to an average relative compaction of 93 percent, with no single test value being below a relative compaction of 91 percent and no single test value being above a relative compaction of 97 percent of the referenced laboratory density according to ASTM D2041. 8.8.9 The asphalt concrete should comply with the requirements for Hot Mixed Asphalt (HMA) as described in Division 5-04 of the State of Washington Department of Transportation Standard Specifications, or the requirements of the governing agency, whichever is most stringent. 8.9 Portland Cement Concrete (PCC) Pavements Recommendations for Portland Cement Concrete pavement structural sections are presented in the following subsections. The design professional should specify where Portland cement concrete pavements are used based on the anticipated type and frequency of traffic. 8.9.1 The subgrade soils for Portland cement concrete pavements should be over- excavated and compacted as recommended in the “Site Preparation” section of the recommendations in this report. As part of the final preparation, the upper 12 inches of the subgrade soils should be moisture conditioned and compacted to a minimum of 95 percent of the maximum dry density determined in accordance with ASTM D 1557. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 29 8.9.2 The following pavement section thicknesses were based upon traffic loading ranging using an Equivalent Single Axle Load (ESAL) of from 47,300 to more frequent truck traffic using an ESAL of up to 410,420. The design pavement sections should be selected by the civil engineer based on the anticipated traffic loading. If higher traffic loading is required, Moore Twining should be contacted and requested to provide additional pavement thicknesses. If the paved areas are to be used during construction, or if the type and frequency of traffic are greater than assumed in design, the pavement section should be re-evaluated for the anticipated traffic. The design structural sections were prepared based on the procedures outlined in the pavement design application www.pavementdesigner.org (Street Analysis), and assuming the following: 1) minimum modulus of rupture of 500 psi for the concrete, 2) a design life of 20 years, 3) load transfer by aggregate interlock or dowels, 4) concrete shoulder, 5) a load safety factor of 1.1, 6) truck loading consisting of a maximum single axle weight of 16,000 pounds, and two (2) tandem axles with a weight of 32,000 pounds. Table No. 5 Portland Cement Concrete Pavements ESAL ADTT PCC thickness (inches) ASC thickness, inches Compacted Subgrade (inches) 47,300 2 6.5 6.0 12.0 164,000 8 6.5 6.0 12.0 410,420 24 7.0 6.0 12.0 ADTT - Average Daily Truck Traffic based on a semi tractor trailer ESAL - Equivalent single 18 kip axle load PCC - Portland Cement Concrete ASC - Aggregate Surface Course and compacted to at least 95 percent relative compaction (ASTM D1557) Subgrade - Subgrade soils compacted to at least 95 percent relative compaction (ASTM D1557) 8.9.3 The PCC pavement should be constructed in accordance with American Concrete Institute requirements, the requirements of the project plans and specifications, whichever is the most stringent. The pavement design engineer should include appropriate construction details and specifications for construction joints, contraction joints, joint filler, concrete specifications, curing methods, etc. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 30 8.9.4 Concrete used for PCC pavements shall possess a minimum flexural strength (modulus of rupture) of 500 pounds per square inch. A minimum compressive strength of 4,000 pounds per square inch, or greater as required by the pavement designer, is recommended. Specifications for the concrete to reduce the effects of excessive shrinkage, such as maximum water requirements for the concrete mix, allowable shrinkage limits, contraction joint construction requirements, etc. should be provided by the designer of the PCC slabs. 8.9.5 Jointing is one of the most critical aspects of the PCC pavement design and construction. Joint spacing, joint type and load transfer devices have significant impacts on the pavement design and performance. Thus, the detailing of joints needs to be considered carefully and applied with clear details on the project plans by the pavement designer/detailer. Positive load transfer devices such as dowels are commonly used at contraction joints whenever the designer cannot be assured aggregate interlock will be maintained. 8.9.6 Specifications for the concrete mixtures used in the PCC pavement to reduce the effects of excessive shrinkage (such as curling and excessive shrinkage at joints), including maximum water requirements for the concrete mix, allowable shrinkage limits, curing methods, etc. should be provided by the designer/detailer of the PCC slabs. In addition, as noted in Section 8.9.5, contraction joint requirements should be detailed by the designer/detailer of the PCC pavement to maintain stability. The minimum PCC thickness noted in this report assumes aggregate interlock occurs at contraction joints. However, curling and excessive shrinkage can disengage aggregate interlock and allow greater pavement deflection at free edges. 8.9.7 Contraction and construction joints should include a joint filler/sealer to prevent migration of water into the subgrade soils. The type of joint filler should be specified by the pavement designer. The joint sealer and filler material should be maintained throughout the life of the pavement. 8.9.8 Contraction joints should have a depth of at least one-fourth the slab thickness, e.g., 1.5-inch for a 6-inch slab. Specifications for contraction joint spacing, timing and depth of sawcuts should be included in the plans and specifications. 8.9.9 Stresses are anticipated to be greater at the edges and construction joints of the pavement section. A thickened edge is recommended on the outside of slabs subjected to wheel loads. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 31 8.9.10 Joint spacing in feet should not exceed twice the slab thickness in inches, e.g., 12 feet by 12 feet for a 6-inch slab thickness. Regardless of slab thickness, joint spacing should not exceed 15 feet. 8.9.11 Lay out joints to form square panels. When this is not practical, rectangular panels can be used if the long dimension is no more than 1.5 times the short. 8.9.12 Isolation (expansion) joints should extend the full depth and should be used only to isolate fixed objects abutting or within paved areas. 8.9.13 Pavement section design assumes that proper maintenance such as sealing and repair of localized distress will be performed on a periodic basis. 8.9.14 Pavement materials and construction methods should conform to Division 5 Section 5-05 Cement Concrete Pavement of the State of Washington Department of Transportation Standard Specifications. 8.10 Underground Fuel Storage Tanks 8.10.1 It is our understanding underground fuel storage tanks extending to a depth of about 20 feet BSG are planned as part of fuel delivery. The excavation for the tanks will be in close proximity to the foundations for the fuel canopies. The contractor needs to consider these conditions in planning the excavation and the footings for the canopies. Since the underground fuel storage tanks are to be backfilled with pea gravel that is encapsulated with a filter fabric, the contractor will need to shore, or selectively backfill the excavation such that a minimum 8-foot horizontal separation is provided between the foundations for the fuel canopies and the pea gravel backfill for the underground fuel storage tank. If required, shoring of excavations should also be employed based on the recommendations for temporary excavations included in Section 8.11 of this report. 8.10.2 The excavation limits, type of backfill, and the compaction requirements for the storage tanks should be specified by the applicable design professional and should be in compliance with the manufacturer’s requirements and the requirements of the governing agency, whichever is more stringent. 8.10.3 If open graded gravel or rock material such as pea gravel or crushed rock is required by a regulatory agency or designer for use as backfill, the material should be placed in thin lifts and compacted using a vibratory compactor or other appropriate methods to a non-yielding condition as determined by Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 32 qualified geotechnical engineering testing firm. The backfill should be conducted in accordance with the tank manufacturer’s requirements, and this report (if applicable per the manufacturer), whichever is most stringent. Each lift must be approved by the qualified geotechnical engineering testing firm prior to placing the next lift. All open graded materials should be fully encased in a geotextile filter fabric to reduce the potential for fines to migrate into the rock section. It should be noted that the use of open graded rock as backfill increases the potential for settlement, migration of water, etc. 8.10.4 Open graded gravel (such as pea gravel) should be placed in thin (less than 8 inch) lifts and densified per section 8.4.8 of this report if vibratory compaction of the pea gravel allowed by the manufacturer. 8.11 Temporary Excavations 8.11.1 It is the responsibility of the contractor to provide safe working conditions with respect to excavation slope stability. The contractor is responsible for site slope safety, classification of materials for excavation purposes, and maintaining slopes in a safe manner during construction. The grades, classification and height recommendations presented for temporary slopes are for consideration in preparing budget estimates and evaluating construction procedures. 8.11.2 Temporary excavations should be constructed in accordance with OSHA requirements. Temporary cut slopes in soils should not be steeper than 1.5:1, horizontal to vertical, and flatter if possible. If excavations cannot meet these criteria, the temporary excavations should be shored. 8.11.3 Shoring should be designed by an engineer with experience in designing shoring systems and registered in the State of Washington. Moore Twining should be provided with the shoring plan to assess whether the plan incorporates the recommendations in the geotechnical engineering investigation report. 8.11.4 Excavation stability should be monitored by the contractor. Slope gradient estimates provided in this report do not relieve the contractor of the responsibility for excavation safety. In the event that tension cracks or distress to the structure occurs, during or after excavation, the Owner should be notified immediately and the contractor should take appropriate actions to minimize further damage or injury. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 33 8.12 Utility Trenches 8.12.1 The utility trench subgrade should be prepared by excavation of a neat trench without disturbance to the bottom of the trench. If sidewalls are unstable, the contractor shall either slope the excavation to create a stable sidewall or shore the excavation. All trench subgrade soils disturbed during excavation, such as by accidental over-excavation of the trench bottom, or by excavation equipment with cutting teeth, should be compacted to a minimum of 92 percent relative compaction prior to placement of bedding material. The contractor is responsible for notifying the qualified geotechnical engineering testing firm when these conditions occur and arrange for the testing firm to observe and test these areas prior to placement of pipe bedding. The contractor shall use such equipment as necessary to achieve a smooth undisturbed native soil surface at the bottom of the trench with no loose material at the bottom of the trench. The contractor shall either remove all loose soils or compact the loose soils as engineered fill prior to placement of bedding, pipe and backfill of the trench. 8.12.2 The trench width, type of pipe bedding, the type of initial backfill, and the compaction requirements of bedding and initial backfill material for utility trenches (storm drainage, sewer, water, electrical, gas, cable, phone, irrigation, etc.) should be specified by the project Civil Engineer or applicable design professional in compliance with the manufacturer’s requirements, governing agency requirements and this report, whichever is more stringent. The contractor is responsible for contacting the governing agency to determine the requirements for pipe bedding, pipe zone and final backfill. The contractor is responsible for notifying the Owner and the qualified geotechnical engineering testing firm if the requirements of the agency and this report conflict, the most stringent applies. For flexible polyvinylchloride (PVC) pipes, these requirements should be in accordance with the manufacturer’s requirements or ASTM D-2321, whichever is more stringent, assuming a hydraulic gradient exists (gravel, rock, crushed gravel, etc. cannot be used as backfill on the project). The width of the trench should provide a minimum clearance of 8 inches between the sidewalls of the pipe and the trench, or as necessary to provide a trench width that is 12 inches greater than 1.25 times the outside diameter of the pipe, whichever is greater. As a minimum, the pipe bedding should consist of 4 inches of compacted (92 percent relative compaction) select sand with a minimum sand equivalent of 30 and meeting the following requirements: 100 percent passing the 1/4 inch sieve, a minimum of 90 percent passing the No. 4 sieve and not more than 10 percent passing the No. 200 sieve. The haunches and initial backfill (12 Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 34 inches above the top of pipe) should consist of a select sand meeting these sand equivalent and gradation requirements that is placed in maximum 6-inch thick lifts and compacted to a minimum relative compaction of 92 percent using hand equipment. The final fill (12 inches above the pipe to the surface) should be on-site or imported, non-expansive materials moisture conditioned to between optimum and three (3) percent above optimum moisture content and compacted to a minimum of 92 percent relative compaction, except the upper 12 inches of trench backfill in pavement areas should be compacted to a minimum of 95 percent relative compaction. The project civil engineer should take measures to control migration of moisture in the trenches such as slurry collars, etc. 8.12.3 If ribbed or corrugated HDPE or metal pipes are used on the project, then the backfill should consist of select sand with a minimum sand equivalent of 30, 100 percent passing the 1/4 inch sieve, a minimum of 90 percent passing the No. 4 sieve and not more than 10 percent passing the No. 200 sieve. The sand shall be placed in maximum 6-inch thick lifts, extending to at least 1 foot above the top of pipe, and compacted to a minimum relative compaction of 92 percent using hand equipment. Prior to placement of the pipe, as a minimum, the pipe bedding should consist of 4 inches of compacted (92 percent relative compaction) sand meeting the above sand equivalent and gradation requirements for select sand bedding. The width of the trench should meet the requirements of ASTM D2321 listed in table below (minimum manufacturer requirements), or to a minimum of 24 inches, whichever is greater. As an alternative to the trench width recommended above and the use of the select sand bedding, a lesser trench width for HDPE pipes may be used if the trench is backfilled with a 2-sack sand-cement slurry from the bottom of the trench to 1 foot above the top of the pipe. Table No. 6 Minimum Trench Widths for HDPE Pipe with Sand Bedding Initial Backfill Inside Diameter of HDPE Pipe (inches) Outside Diameter of HDPE Pipe (inches) Minimum Trench Width (inches) per ASTM D2321 12 14.2 30 18 21.5 39 24 28.4 48 36 41.4 64 48 55 80 Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 35 8.12.4 Open graded gravel and rock material such as ¾-inch crushed rock or ½-inch crushed rock should not be used as backfill including trench backfill. In the event gravel or rock is required by a regulatory agency for use as backfill (Contractor to obtain a letter from the agency stating the requirement for rock and/or gravel as backfill), all open graded materials shall be fully encased in a geotextile filter fabric, such as Mirafi 140N, to prevent migration of fine grained soils into the porous material. Gravel and rock cannot be used without the written approval of Moore Twining. If the contractor elects to use crushed rock (and if approved by Moore Twining), the contractor will be responsible for slurry cut off walls at the locations specified by Moore Twining. Crushed rock should be placed in thin (less than 8 inch) lifts and densified with a minimum of three (3) passes using a vibratory compactor. 8.12.5 Utility trenches should be a minimum width of 24 inches. Utility trench backfill placed in or adjacent to building areas, exterior slabs or pavements should be placed in 8 inch lifts, moisture conditioned to between optimum and three (3) percent above the optimum moisture content and compacted to at least 92 percent of the maximum dry density as determined by ASTM Test Method D1557, except the upper 12 inches of trench backfill in pavement areas should be compacted to a minimum of 95 percent relative compaction. Lift thickness can be increased if the contractor can demonstrate the minimum compaction requirements can be achieved. The contractor should use appropriate equipment and methods to avoid damage to utilities and/or structures during placement and compaction of the backfill materials. 8.12.6 On-site soils and approved imported engineered fill may be used as final backfill (12 inches above the pipe to the ground surface) in trenches 8.12.7 Jetting of trench backfill is not allowed to compact the backfill soils. 8.12.8 Where utility trenches extend from the exterior to the interior limits of a building, lean concrete should be used as backfill material for a minimum distance of 2 feet laterally on each side of the exterior building line to prevent the trench from acting as a conduit to exterior surface water. 8.12.9 Storm drains and/or utility lines should be designed to be “watertight.” If encountered, leaks should be immediately repaired. Leaking storm drain and/or utility lines could result in trench failure, sloughing and/or soil movement causing damage to surface and subsurface structures, pavements, flatwork, etc. In addition, landscaping irrigation systems should be monitored for leaks. The Contractor is required to video inspect or pressure test the wet Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 36 utilities prior to placement of foundations, slabs-on-grade or pavements to verify that the pipelines are constructed properly and are “watertight.” The Contractor shall provide the Owner a copy of the results of the testing. The Contractor is required to repair all noted deficiencies at no cost to the owner. 8.12.10The plans should note that all utility trenches, including electrical lines, irrigation lines, etc. should be compacted to a minimum relative compaction of 92 percent per ASTM D-1557 except for the upper 12 inches below pavements which should be compacted to at least 95 percent relative compaction. 8.12.11Utility trenches should not be constructed within a zone defined by a line that extends at an inclination of 2 horizontal to 1 vertical downward from the bottom of building foundations. 8.13 Corrosion Protection 8.13.1 Based on National Association of Corrosion Engineers (NACE) corrosion severity ratings listed in the Table No. 1 and the analytical results of sample analyses indicate the sample tested had a resistivity value of 61,000 ohms- centimeter. Based on the resistivity value, the soils exhibit a “essentially on- corrosive” corrosion potential. Therefore, buried metal objects should be protected in accordance with the manufacturer's recommendations based on a “essentially non-corrosive” corrosion potential. The evaluation was limited to the effects of soils to metal objects; corrosion due to other potential sources, such as stray currents and groundwater, was not evaluated. If piping or concrete are placed in contact with deeper soils or engineered fill, these soils should be analyzed to evaluate the corrosion potential of these soils. 8.13.2 Based on Table 19.3.1.1 - Exposure categories and classes from Chapter 19 of ACI 318, the sulfate concentration from chemical testing of soil samples falls in the S0 classification (less than 0.10 percent by weight) for concrete. Therefore, there are no restrictions required regarding the type, water-to- cement ratio, and strength of the concrete used for foundation and slabs due to the sulfate content. However, a low water to cement ratio is recommended for slabs on grade as recommended in the “Interior Slab on Grade” section of this report. 8.13.3 These soil corrosion data should be provided to the manufacturers or suppliers of materials that will be in contact with soils (pipes or ferrous metal objects, etc.) to provide assistance in selecting the protection and materials for the proposed products or materials. If the manufacturers or suppliers Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 37 cannot determine if materials are compatible with the soil corrosion conditions, a professional consultant, i.e., a corrosion engineer, with experience in corrosion protection should be consulted to design parameters. Moore Twining is not a corrosion engineer; thus, cannot provide recommendations for mitigation of corrosive soil conditions. It is recommended that a corrosion engineer be consulted for the site specific conditions. 9.0 DESIGN CONSULTATION 9.1 Moore Twining should be retained to review those portions of the contract drawings and specifications that pertain to earthwork operations, pavements and foundations prior to finalization to determine whether they are consistent with our recommendations. This service is not part of this current contractual agreement.. 9.2 It is the client's responsibility to provide plans and specification documents for our review prior to their issuance for construction bidding purposes. 9.3 If Moore Twining is not retained for the plan review, we assume no liability for the misinterpretation of our conclusions and recommendations. This review is documented by a formal plan/specification review report provided by Moore Twining. 10.0 CONSTRUCTION MONITORING 10.1 A qualified geotechnical engineering testing firm should be retained to observe the excavation, earthwork, and foundation phases of work to determine that the subsurface conditions are compatible with those used in the analysis and design. Upon completion of the work, a written summary of observations, field testing and conclusions should be prepared by the qualified geotechnical engineering testing firm regarding the conformance of the completed work to the intent of the plans and specifications. 10.2 In the event that the earthwork operations for this project are conducted such that the construction sequence is not continuous, (or if construction operations disturb the surface soils) it is recommended that the exposed subgrade that will receive floor slabs be tested to verify adequate compaction and/or moisture conditioning. If adequate compaction or moisture contents are not verified, the fill soils should be over-excavated, scarified, moisture conditioned and compacted are recommended in the Recommendations of this report. 10.3 The qualified geotechnical engineering testing firm should, in writing, state that they understand the conclusions and recommendations of this report and agree to conduct sufficient observations and testing to ensure the construction complies with this report's recommendations. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 38 11.0 NOTIFICATION AND LIMITATIONS 11.1 The conclusions and recommendations presented in this report are based on the information provided regarding the proposed construction, and the results of the field and laboratory investigation, combined with interpolation of the subsurface conditions between boring locations. The nature and extent of subsurface variations between borings may not become evident until construction. 11.2 If variations or undesirable conditions are encountered during construction, Moore Twining should be notified promptly so that these conditions can be reviewed and our recommendations reconsidered where necessary. It should be noted that unexpected conditions frequently require additional expenditures for proper construction of the project. 11.3 If the proposed construction is relocated or redesigned, or if there is a substantial lapse of time between the submission of our report and the start of work (over 12 months) at the site, or if conditions have changed due to natural cause or construction operations at or adjacent to the site, the conclusions and recommendations contained in this report should be considered invalid unless the changes are reviewed and our conclusions and recommendations modified or approved in writing. 11.4 Changed site conditions, or relocation of proposed structures, may require additional field and laboratory investigations to determine if our conclusions and recommendations are applicable considering the changed conditions or time lapse. 11.5 The conclusions and recommendations contained in this report are valid only for the project discussed in Section 3.3, Anticipated Construction. The use of the information and recommendations contained in this report for structures on this site not discussed herein or for structures on other sites not discussed in this report is not recommended. The entity or entities that use or cause to use this report or any portion thereof for other structures or site not covered by this report shall hold Moore Twining, its officers and employees harmless from any and all claims and provide Moore Twining’s defense in the event of a claim. 11.6 This report is issued with the understanding that it is the responsibility of the client to transmit the information and recommendations of this report to developers, owners, buyers, architects, engineers, designers, contractors, subcontractors, and other parties having interest in the project so that the steps necessary to carry out these recommendations in the design, construction and maintenance of the project are taken by the appropriate party. 11.7 This report presents the results of a geotechnical engineering investigation only and should not be construed as an environmental audit or study. Geotechnical Engineering Investigation G28867.01 Proposed Circle K Store March 20, 2024 NWC of Yelm Avenue and Killion Road, Yelm Washington Page No. 39 11.8 Our professional services were performed, our findings obtained, and our recommendations prepared in accordance with generally -accepted engineering principles and practices. This warranty is in lieu of all other warranties either expressed or implied. 11.9 Reliance on this report by a third party (i.e., that is not a party to our written agreement) is at the party's sole risk. If the project and/or site are purchased by another party, the purchaser must obtain written authorization and sign an agreement with Moore Twining in order to rely upon the information provided in this report for design or construction of the project. We appreciate the opportunity to be of service to Circle K Stores, Inc. If you have any questions regarding this report, or if we can be of further assistance, please contact us at your convenience. Sincerely, MOORE TWINING ASSOCIATES, INC. Geotechnical Engineering Division Alan Villegas Staff Engineer Read Andersen Manager Harry D. Moore, PE Principal Engineer A-1 G28867.01 APPENDIX A DRAWINGS Drawing No. 1 - Site Location Map Drawing No. 2 - Test Pit and Boring Location Map - Proposed Improvements Drawing No. 3 - Test Pit and Boring Location Map - Existing Condition SITE 20000 IN FEET APPROXIMATE SCALE SOURCE: U.S.G.S. TOPOGRAPHIC MAP, 7 ½ MINUTE SERIES DATE: APPROVED BY: 1 DRAWING NO. FILE NO.: DRAWN BY: PROJECT NO. RM G28867.01 McKENNA, WASHINGTON QUADRANGLE SITE LOCATION MAP CIRCLE K STORES INC. NWC YELM AVENUE & KILLION ROAD YELM, WASHINGTON 28867-01-01 03/15/2024 03/18/2024 DRAWING NO. APPROVED BY: DATE DRAWN: PROJECT NO. G28867.01 RM DRAWN BY: FILE NO. 2 28867-01-02 TEST BORING AND TEST PIT LOCATION MAP CIRCLE K STORE INC. - PROPOSED IMPROVEMENTS NWC YELM AVENUE & KILLION ROAD YELM, WASHINGTON APPROXIMATE TEST BORING LOCATION APPROXIMATE TEST PIT LOCATION IN FEET APPROXIMATE SCALE N 0 60 03/18/2024 DRAWING NO. APPROVED BY: DATE DRAWN: PROJECT NO. G28867.01 RM DRAWN BY: FILE NO. 3 28867-01-02 TEST BORING AND TEST PIT LOCATION MAP CIRCLE K STORE INC. - EXISTING CONDITIONS NWC YELM AVENUE & KILLION ROAD YELM, WASHINGTON APPROXIMATE TEST BORING LOCATION APPROXIMATE TEST PIT LOCATION IN FEET APPROXIMATE SCALE N 0 60 B-1 G28867.01 APPENDIX B LOGS OF TEST PITS AND BORINGS This appendix contains the final logs of the test pits and borings. These logs represent our interpretation of the contents of the field logs and the results of the field and laboratory tests. The logs and related information depict subsurface conditions only at these locations and at the particular time designated on the logs. Soil conditions at other locations may differ from conditions occurring at these test boring locations. Also, the passage of time may result in changes in the soil conditions at these test boring locations. In addition, an explanation of the abbreviations used in the preparation of the logs and a description of the Unified Soil Classification System are provided at the end of Appendix B. 0 2 4 6 8 10 SM GP GW POORLY GRADED GRAVEL WITH SAND; moist, fine to coarse grained, brown, with cobble WELL GRADED GRAVEL WITH SAND moist, fine to coarse grained, grayish brown, with cobble Collapsing sidewalls With trace boulders Bottom of test pit TP-1 at 8 feet. +4=68.4% Sand=28.4% -200=3.2% 7.5 Project Number:G28867.01 Logged By:A.V. Drilled By:ClearCreek Date:February 8, 2024 Drill Type:Kubota KX040 Elevation: Auger Type:NA Depth to Groundwater Hammer Type:NA First Encountered During Drilling:NE Notes: Figure Number ELEVATION/ DEPTH (feet) SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA USCS Soil Description Remarks N-Values blows/ft. Moisture Content % Project:Proposed Circle K Store; Yelm Avenue and Kllion Road, Yelm, WA Test Pit: TP-1 SILTY SAND; moist, fine to coarse grained, dark brown, with grass roots (top soil) 0 2 4 6 8 10 SM GP GW POORLY GRADED GRAVEL WITH SAND AND COBBLE; moist, fine to coarse grained, brown, with a 14-inch diameter boulder WELL GRADED GRAVEL WITH SAND WITH COBBLE; moist, fine to coarse grained, grayish brown Some <14" diameter boulders Bottom of test pit TP-2 at 8.5 feet. 17.0 3.5 Project Number:G28867.01 Logged By:A.V. Drilled By:ClearCreek Date:February 8, 2024 Drill Type:Kubota KX040 Elevation: Auger Type:NA Depth to Groundwater Hammer Type:NA First Encountered During Drilling:NE Notes: Figure Number ELEVATION/ DEPTH (feet) SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA USCS Soil Description Remarks N-Values blows/ft. Moisture Content % Project:Proposed Circle K Store; Yelm Avenue and Killion Road, Yelm, WA Test Pit :TP-2 SILTY SAND WITH GRAVEL; moist, fine to coarse grained, dark brown, with grass roots (top soil) 0 2 4 6 8 10 SM GP GW POORLY GRADED GRAVEL AND SAND; moist, fine to coarse grained, brown, with some cobble Increase in sand and cobble content, with thin seams of poorly graded sand with gravel WELL GRADED GRAVEL AND SAND; moist, fine to coarse grained, grayish brown Collapsing sidewalls Bottom of test pit TP-3 at 8.5 feet. RV=77 7.1 Project Number:G28867.01 Logged By:A.V. Drilled By:ClearCreek Date:February 8, 2024 Drill Type:Kubota KX040 Elevation: Auger Type:NA Depth to Groundwater Hammer Type:NA First Encountered During Drilling:NE Notes: Figure Number ELEVATION/ DEPTH (feet) SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA USCS Soil Description Remarks N-Values blows/ft. Moisture Content % Test Pit: TP-3 Project:Proposed Circle K Store; Yelm Avenue and Killion Road, Yelm, WA SILTY SAND WITH GRAVEL; moist, fine to coarse grained, dark brown, with grass roots (top soil) 0 2 4 6 8 10 SP-SM GP-GM POORLY GRADED GRAVEL WITH SILT AND SAND; moist, fine to coarse grained, brown, with some cobble With cobble with trace boulders Collapsing sidewalls Bottom of test pit TP-4 at 8.5 feet. +4=45.2% Sand=47.6% -200=7.2% Organics=8.9% PI=NP LL=NV -200=5.3% 9.3 4.5 Project Number:G28867.01 Logged By:A.V. Drilled By:ClearCreek Date:February 8, 2024 Drill Type:Kubota KX040 Elevation: Auger Type:NA Depth to Groundwater Hammer Type:NA First Encountered During Drilling:NE Notes: Figure Number ELEVATION/ DEPTH (feet) SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA USCS Soil Description Remarks N-Values blows/ft. Moisture Content % Test Pit: TP-4 Project:Proposed Circle K Store; Yelm Avenue and Killion Road, Yelm, WA POORLY GRADED SAND WITH SILT AND GRAVEL; moist, fine to coarse grained, dark brown, with some gravel, with 1.5-inch roots (top soil) 0 2 4 6 8 10 SM SP-SM GP POORLY GRADED SAND WITH SILT AND GRAVEL; moist, fine to coarse grained, brown, with some cobble increasing gravel content with depth POORLY GRADED GRAVEL WITH SAND; moist, fine to coarse grained, brown, with cobble Bottom of test pit TP-5 at 7.8 feet. 14.1 4.1 Project Number:G28867.01 Logged By:A.V. Drilled By:ClearCreek Date:February 8, 2024 Drill Type:Kubota KX040 Elevation: Auger Type:NA Depth to Groundwater Hammer Type:NA First Encountered During Drilling:NE Notes: Figure Number ELEVATION/ DEPTH (feet) SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA USCS Soil Description Remarks N-Values blows/ft. Moisture Content % Test Pit: TP-5 Project:Proposed Circle K Store; Yelm Avenue and Killion Road, Yelm, WA SILTY SAND; moist, fine to medium grained, dark brown, with some fine to coarse gravel, with 2-inch roots (top soil) 0 2 4 6 8 10 SM GP SP GP POORLY GRADED SAND WITH GRAVEL; moist, fine to coarse grained, brown, with some cobble Sidewall collapsing POORLY GRADED GRAVEL WITH SAND; moist, fine to coarse grained, brown, with cobble Bottom of test pit TP-6 at 9 feet. 8.2 4.2 7.5 Project Number:G28867.01 Logged By:A.V. Drilled By:ClearCreek Date:February 8, 2024 Drill Type:Kubota KX040 Elevation: Auger Type:NA Depth to Groundwater Hammer Type:NA First Encountered During Drilling:NE Notes: Figure Number ELEVATION/ DEPTH (feet) SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA USCS Soil Description Remarks N-Values blows/ft. Moisture Content % Test Pit: TP-6 Project:Proposed Circle K Store; Yelm Avenue and Killion Road, Yelm, WA POORLY GRADED GRAVEL WITH SAND; moist, fine to coarse grained, brown, with cobble SILTY SAND WITH GRAVEL; moist, fine to coarse grained, brown, with 1-inch roots (top soil) 0 2 4 6 8 10 SM SP-SM GP GW POORLY GRADED SAND WITH SILT AND GRAVEL; moist, fine to coarse grained, brown POORLY GRADED GRAVEL WITH SAND; moist, fine to coarse grained, light brown, with some cobble With trace boulders (<13-inch diameter) WELL GRADED GRAVEL WITH SAND; moist, fine to coarse grained, brown, with some cobble and boulders Bottom of test pit TP-7 at 7.5 feet. RV=75 12.9 Project Number:G28867.01 Logged By:A.V. Drilled By:ClearCreek Date:February 8, 2024 Drill Type:Kubota KX040 Depth to Groundwater Hammer Type:NA First Encountered During Drilling:NE Notes: Figure Number ELEVATION/ DEPTH (feet) SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA USCS Soil Description Remarks N-Values blows/ft. Moisture Content % Project:Proposed Circle K Store; Yelm Avenue and Killion Road, Yelm, WA Test Pit: TP-7 Elevation: Auger Type:NA SILTY SAND; moist, fine to medium grained, dark brown, with some gravel, with 2-inch roots (top soil) 0 5 10 15 20 25 4/6 11/6 22/6 7/6 9/6 11/6 17/6 30/6 39/6 14/6 14/6 24/6 17/6 31/6 32/6 14/6 15/6 16/6 SM GP-GM GW With large cobble Medium dense Increase in sand content Very dense WELL GRADED GRAVEL WITH SILT SAND; very dense, moist, fine to coarse grained, gray-brown, with cobble Dense, very moist Very dense, with some clay -200=11.0% 33 20 >50 >50 31 8.9 5.5 5.7 3.7 Test Boring: B-1 Project Number:G28867.01 Logged By:A.V. Drilled By:Holt Services Date:March 4, 2024 Drill Type:Terra Sonic TSI 150 Depth to Groundwater Hammer Type:140 Lbs Auto-trip First Encountered During Drilling:30 Feet Notes: Figure Number ELEVATION/ DEPTH (feet) SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA USCS Soil Description Remarks N-Values blows/ft. Moisture Content % Project:Proposed Circle K; Yelm Avenue and Killion Road, Yelm, WA 38 Elevation: Auger Type:5" Core Barrel and 6" Casing SILTY SAND WITH GRAVEL; dense, moist, fine to coarse grained, dark brown, with organics (top soil) POORLY GRADED GRAVEL WITH SILT SAND; dense, moist, fine to coarse grained, gray-brown 30 35 40 45 50 55 25/6 34/6 36/6 32/6 31/6 21/6 25/6 50/1 50/3" GC Wet Slight increase in gravel content CLAYEY GRAVEL WITH SAND; very dense, wet, fine to coarse grained, brown Bottom of boring B-1 at 50.3 feet >50 52 >50 >50 Test Boring: B-1 Project Number:G28867.01 Logged By:A.V. Drilled By:Holt Services Date:March 4, 2024 Drill Type:Terra Sonic TSI 150 Depth to Groundwater Hammer Type:140 Lbs Auto-trip First Encountered During Drilling:30 Feet Notes: Figure Number ELEVATION/ DEPTH (feet) SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA USCS Soil Description Remarks N-Values blows/ft. Moisture Content % Project:Proposed Circle K; Yelm Avenue and Killion Road, Yelm, WA Elevation: Auger Type:5" Core Barrel and 6" Casing 0 5 10 15 20 25 SM GP-GM GW Increase in cobble content very moist Slight increase in sand content Increase in fine gravel content Bottom of boring B-2 at 25 feet +4=66.4% Sand=28% -200=5.6% 19.5 12.6 7.5 6.2 5.5 Test Boring: B-2 Project Number:G28867.01 Logged By:A.V. Drilled By:Holt Services Date:March 4, 2024 Drill Type:Terra Sonic TSI 150 Depth to Groundwater Hammer Type:140 Lbs Auto-trip First Encountered During Drilling:30 Feet Notes: Figure Number ELEVATION/ DEPTH (feet) SOIL SYMBOLS SAMPLER SYMBOLS AND FIELD TEST DATA USCS Soil Description Remarks N-Values blows/ft. Moisture Content % Project:Proposed Circle K; Yelm Avenue and Killion Road, Yelm, WA Elevation: Auger Type:5" Core Barrel and 6" Casing with 6-inch lense of poorly graded sand with gravel WELL GRADED GRAVEL WITH SILT AND SAND; moist, fine to coarse grained, with cobble SILTY SAND WITH GRAVEL; very moist, fine to coarse grained, dark brown, with grass roots (top soil) POORLY GRADED GRAVEL WITH SILT AND SAND; moist, fine to coarse grained, brown, with trace cobble 2. Groundwater was encountered at 30 feet in test boring B-1. 3. Boring locations were measured or paced from existing features. 5. The "N-value" reported for the California Modified Split Barrel Sampler is the uncorrected field blow count. This value should not be interpreted as an SPT equivalent N-value. 6. Results of tests conducted on samples recovered are reported on the logs. Notes: Symbol Description Strata symbols Silty sand Poorly graded gravel with silt Well graded gravel Clayey gravel Symbol Description Misc. Symbols Boring continues Water table during drilling Soil Samplers Standard penetration test Bulk/Grab sample KEY TO SYMBOLS DD = Natural dry density (pcf) LL = Liquid Limit (%) +4 = Percent retained on the No. 4 sieve(%) PI = Plasticity Index (%) -200 = Percent passing the No. 200 sieve (%) EI = Expansion Index Sand = Percent passing the No. 4 sieve Gravel = Percent passing 3-inch & and retained on No. 200 sieve (%) retained on No. 4 sieves(%) pH = Soil pH SR = Soil resistivity (ohms- cm) SS = Soluble sulfates (%) Cl = Soluble chlorides (%) ø = Internal Angle of Friction (degrees) c = Cohesion (psf) pcf = Pounds per cubic foot psf = Pounds per square foot O.D. = Outside diameter AMSL = Above mean sea level N/A = Not applicable N/E = Not encountered LOI = Loss on Ignition 1. Exploratory borings were drilled on 3/4/2024 using a Terra Sonic 150 drill rig equipped with 6" diameter casing and 5" Core Barrel. The exploratory tests pits were drilled on 2/8/2024 using a mini-excavator using a 2-foot wide bucket. 4. These logs are subject to the limitations, conclusions, and recommendations in this report. C-1 G28867.01 APPENDIX C RESULTS OF LABORATORY TESTS This appendix contains the individual results of the following tests. The results of the moisture content and dry density tests are included on the test boring logs in Appendix B. These data, along with the field observations, were used to prepare the final test boring logs in Appendix B. These Included: To Determine: Moisture Content (ASTM D2216) Moisture contents representative of field conditions at the time the sample was taken. Dry Density (ASTM D2216) Dry unit weight of sample representative of in-situ or in-place undisturbed condition. Grain-Size Distribution (ASTM D422) Size and distribution of soil particles, i.e., sand, gravel and fines (silt and clay). Atterberg Limits (ASTM D4318) Expansion Index (ASTM D4829) Determines the moisture content where the soil behaves as a viscous material (liquid limit) and the moisture content at which the soil reaches a plastic state Swell potential of soil with increases in moisture content. R-Value (ASTM D 2844) The capacity of a subgrade or subbase to support a pavement section designed to carry a specified traffic load. Sulfate Content (Cal Test 417) Percentage of water-soluble sulfate as (SO4) in soil samples. Used as an indication of the relative degree of sulfate attack on concrete and for selecting the cement type. Chloride Content (Cal Test 422) Percentage of soluble chloride in soil. Used to evaluate the potential attack on encased reinforcing steel. Resistivity (ASTM G187) The potential of the soil to corrode metal. pH (Cal Test 643) The acidity or alkalinity of subgrade material. (X=NO)PERCENTFINERSIZE PASS?SPEC.*PERCENTSIEVE Project No: Project: Client: Elev./Depth:Location: Date:Source of Sample:Sample No.: Remarks Classification Coefficients Atterberg Limits Material Description * AASHTO=USCS= Cc=Cu= D10=D15=D30= D50=D60=D85= PI=LL=PL= Particle Size Distribution Report 10 20 30 40 50 60 70 80 90 0 100 PE R C E N T F I N E R 100 10 1 0.1 0.01 0.001500 GRAIN SIZE - mm % COBBLES % GRAVEL CRS.FINE % SAND CRS.MEDIUM FINE % FINES SILT CLAY 6 i n . 3 i n . 2 i n . 1- 1 / 2 i n . 1 i n . 3/ 4 i n . 1/ 2 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 0.0 41.2 27.2 6.5 13.5 8.4 3.2 FigureG28867.01 2-7' 2/8/24TP-1 GW 2.2454.07 0.3670.5784.04 14.119.942.4 Well-graded gravel with sand (no specification provided) Moore Twining Associates, Inc. Fresno, CA 100.097.191.480.967.058.847.241.631.626.121.515.48.14.63.2 3 in.2-1/2 in.2 in.1-1/2 in.1 in.3/4 in.1/2 in.3/8 in.#4#8#16#30#50#100#200 Proposed Circle K - Yelm WA (X=NO)PERCENTFINERSIZE PASS?SPEC.*PERCENTSIEVE Project No: Project: Client: Elev./Depth:Location: Date:Source of Sample:Sample No.: Remarks Classification Coefficients Atterberg Limits Material Description * AASHTO=USCS= Cc=Cu= D10=D15=D30= D50=D60=D85= PI=LL=PL= Particle Size Distribution Report 10 20 30 40 50 60 70 80 90 0 100 PE R C E N T F I N E R 100 10 1 0.1 0.01 0.001500 GRAIN SIZE - mm % COBBLES % GRAVEL CRS.FINE % SAND CRS.MEDIUM FINE % FINES SILT CLAY 6 i n . 3 i n . 2 i n . 1- 1 / 2 i n . 1 i n . 3/ 4 i n . 1/ 2 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 0.0 20.9 24.3 8.3 17.7 21.6 7.2 FigureG28867.01 0-1.8' 2/8/24TP-4 SP-SM 0.2050.81 0.1390.2220.446 3.007.0426.2 NPNVNP Poorly graded sand with silt and gravel (no specification provided) Moore Twining Associates, Inc. Fresno, CA 100.097.393.284.479.169.564.554.847.942.836.420.410.67.2 2-1/2 in.2 in.1-1/2 in.1 in.3/4 in.1/2 in.3/8 in.#4#8#16#30#50#100#200 Proposed Circle K - Yelm WA (X=NO)PERCENTFINERSIZE PASS?SPEC.*PERCENTSIEVE Project No: Project: Client: Elev./Depth:Location: Date:Source of Sample:Sample No.: Remarks Classification Coefficients Atterberg Limits Material Description * AASHTO=USCS= Cc=Cu= D10=D15=D30= D50=D60=D85= PI=LL=PL= Particle Size Distribution Report 10 20 30 40 50 60 70 80 90 0 100 PE R C E N T F I N E R 100 10 1 0.1 0.01 0.001500 GRAIN SIZE - mm % COBBLES % GRAVEL CRS.FINE % SAND CRS.MEDIUM FINE % FINES SILT CLAY 6 i n . 3 i n . 2 i n . 1- 1 / 2 i n . 1 i n . 3/ 4 i n . 1/ 2 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 5.3 FigureG28867.01 2.5-3.5' 2/8/24TP-4 SP-SM (no specification provided) Moore Twining Associates, Inc. Fresno, CA Poorly graded Gravel with silt and sand #200 5.3 Proposed Circle K - Yelm WA (X=NO)PERCENTFINERSIZE PASS?SPEC.*PERCENTSIEVE Project No: Project: Client: Elev./Depth:Location: Date:Source of Sample:Sample No.: Remarks Classification Coefficients Atterberg Limits Material Description * AASHTO=USCS= Cc=Cu= D10=D15=D30= D50=D60=D85= PI=LL=PL= Particle Size Distribution Report 10 20 30 40 50 60 70 80 90 0 100 PE R C E N T F I N E R 100 10 1 0.1 0.01 0.001500 GRAIN SIZE - mm % COBBLES % GRAVEL CRS.FINE % SAND CRS.MEDIUM FINE % FINES SILT CLAY 6 i n . 3 i n . 2 i n . 1- 1 / 2 i n . 1 i n . 3/ 4 i n . 1/ 2 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 11.0 FigureG28867.01 10-11.5' 3/4/24B-1 (no specification provided) Moore Twining Associates, Inc. Fresno, CA 11.0#200 Proposed Circle K - Yelm WA (X=NO)PERCENTFINERSIZE PASS?SPEC.*PERCENTSIEVE Project No: Project: Client: Elev./Depth:Location: Date:Source of Sample:Sample No.: Remarks Classification Coefficients Atterberg Limits Material Description * AASHTO=USCS= Cc=Cu= D10=D15=D30= D50=D60=D85= PI=LL=PL= Particle Size Distribution Report 10 20 30 40 50 60 70 80 90 0 100 PE R C E N T F I N E R 100 10 1 0.1 0.01 0.001500 GRAIN SIZE - mm % COBBLES % GRAVEL CRS.FINE % SAND CRS.MEDIUM FINE % FINES SILT CLAY 6 i n . 3 i n . 2 i n . 1- 1 / 2 i n . 1 i n . 3/ 4 i n . 1/ 2 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 0.0 33.7 32.7 5.1 14.0 8.9 5.6 FigureG28867.01 18-20' 3/4/24B-2 GW-GM 1.6059.23 0.2680.4432.61 11.315.931.4 Well-graded gravel with silt and sand (no specification provided) Moore Twining Associates, Inc. Fresno, CA 100.091.677.166.353.145.733.629.524.418.410.97.25.6 2 in.1-1/2 in.1 in.3/4 in.1/2 in.3/8 in.#4#8#16#30#50#100#200 Proposed Circle K - Yelm WA %<#200%<#40PIPLLLMATERIAL DESCRIPTION LIQUID AND PLASTIC LIMITS TEST REPORT Source: Sample No.: TP-4 Elev./Depth: 0-1.8' Figure Moore Twining Associates, Inc. Fresno, CA USCS G28867.01 SP-SM7.228.8NPNPNVPoorly graded sand with silt and gravel 10 30 50 70 90 110 LIQUID LIMIT 10 20 30 40 50 60 PL A S T I C I T Y I N D E X 4 7 CL-ML C L o r O L C H o r O H ML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils Proposed Circle K Project No. Client: Remarks: Project: R-VALUE TEST REPORT Moore Twining Associates, Inc. R-VALUE TEST REPORT Date: 2/21/2024 Remarks: Checked by: MS Tested by: MS Silty sand with gravel & Organic Figure N/A Material DescriptionTest Results No. Compact. Pressure psi Density pcf Moist. % Expansion Pressure psi Horizontal Press. psi @ 160 psi Sample Height in. Exud. Pressure psi R Value R Value Corr. Resistance R-Value and Expansion Pressure - ASTM D 2844 Exp. pressure at 300 psi exudation pressure = 0.38 psi R-value at 300 psi exudation pressure = 77 1 350 113.6 15.7 0.45 20 2.54 430 78 78 2 350 109.2 16.7 0.15 45 2.61 103 57 60 3 350 110.9 16.2 0.30 28 2.58 215 70 72 Exudation Pressure - psi R - v a l u e E x p a n s i o n P r e s s u r e ( p s i ) 100 200 300 400 500 600 700 800 0 0 20 0.2 40 0.4 60 0.6 80 0.8 100 1 Project No.: G28867.01 Project:Proposed Circle K - Yelm WA Sample Number: TP-3 Depth: 0-3.5' R-VALUE TEST REPORT Moore Twining Associates, Inc. R-VALUE TEST REPORT Date: 2/21/2024 Remarks: Checked by: MS Tested by: CG Silty sand with gravel & Organic Figure N/A Material DescriptionTest Results No. Compact. Pressure psi Density pcf Moist. % Expansion Pressure psi Horizontal Press. psi @ 160 psi Sample Height in. Exud. Pressure psi R Value R Value Corr. Resistance R-Value and Expansion Pressure - ASTM D 2844 Exp. pressure at 300 psi exudation pressure = 0.31 psi R-value at 300 psi exudation pressure = 75 1 350 105.4 18.1 0.24 29 2.69 167 68 72 2 350 107.3 17.1 0.45 20 2.64 509 76 79 3 350 105.8 17.6 0.30 25 2.67 294 72 75 Exudation Pressure - psi R - v a l u e E x p a n s i o n P r e s s u r e ( p s i ) 100 200 300 400 500 600 700 800 0 0 20 0.2 40 0.4 60 0.6 80 0.8 100 1 Project No.: G28867.01 Project:Proposed Circle K - Yelm WA Sample Number: TP-7 Depth: 0-3.5' www.mooretwining.com PH: 559.268.7021 FX : 559.268.7126 2527 Fresno Street Fresno, CA 93721 Project No: G28867.01 Sample Location: TP-4 @ 0-1.8' Sampled By: AV Sample Date: 2/8/2024 Material Description: Poorly graded sand with silt and gravel Start Weight, gm: Final Weight, gm: Tare Weight, gm Percent of Organic, %: 8.9 115.6 109.9 51.4 Materials Testing Report ASTM D2974 Tested By: Date Tested: Project: Proposed Circle K - Yelm WA Report Date: www.mooretwining.com PH: 559.268.7021 FX: 559.268.7126 2527 Fresno Street Fresno, CA 93721 Project Number: G28867.01 Sampled By: AV Subject: Minimum Resistivity, ASTM G187 Tested By: RS Material Description: Silty sand with gravel Test Date: 2/20/2024 Location: TP-3 @ 0-3.5' Total Water Added, mls Resistivity, Ohm-cm 50 mls 75 mls 100 mls 125 mls 150 mls 175 mls 200 mls 225 mls 250 mls 275 mls Remarks: Min. Resistivity is Ohm-cm 63,000 61,000 63,000 63,000 61,000 70,000 65,000 Laboratory Test Results, Minimum Resistivity - ASTM G187 Report Date: 220,000 101,000 82,000 72,000 Project Name: Proposed Circle K - Yelm WA 2/20/2024 Sample Date: 2/8/2024 2527 Fresno Street Fresno, CA 93721 (559) 268-7021 Phone (559) 268-0740 Fax March 11, 2024 California ELAP Certificate #1371 Alan Villegas MTA Geotechnical Division Fresno, CA 93721 2527 Fresno Street KB14017Work Order #: Enclosed are the analytical results for samples received by our laboratory on 02/14/24 . For your reference, these analyses have been assigned laboratory work order number KB14017. All analyses have been performed according to our laboratory 's quality assurance program. All results are intended to be considered in their entirety, Moore Twining Associates, Inc. (MTA) is not responsible for use of less than complete reports. Results apply only to samples analyzed. If you have any questions, please feel free to contact us at the number listed above. Sincerely, Moore Twining Associates, Inc. Lauren Cox Client Services Representative RE: Proposed Circle K - Yelm WA Project: Project Number: Project Manager: MTA Geotechnical Division 2527 Fresno Street G28867.01 Alan Villegas Proposed Circle K Fresno CA, 93721 2527 Fresno Street Fresno, CA 93721 (559) 268-7021 Phone (559) 268-0740 Fax 03/11/2024 California ELAP Certificate #1371 Reported: Analytical Report for the Following Samples Sample ID MatrixLaboratory ID Date Sampled Date ReceivedNotes TP-3 @ 0-3.5 KB14017-01 02/08/24 00:00 02/14/24 12:50Soil Moore Twining Associates, Inc.The results in this report apply to the samples analyzed in accordance with the chain of custody document. This analytical report must be reproduced in its entirety.Danielle Abrames, Director of Analytical Chemistry Page 2 of 5 Project: Project Number: Project Manager: MTA Geotechnical Division 2527 Fresno Street G28867.01 Alan Villegas Proposed Circle K Fresno CA, 93721 2527 Fresno Street Fresno, CA 93721 (559) 268-7021 Phone (559) 268-0740 Fax 03/11/2024 California ELAP Certificate #1371 Reported: TP-3 @ 0-3.5 KB14017-01 (Soil) FlagMethodAnalyzedPreparedBatchUnitsResultAnalyteReporting Limit Inorganics ND [CALC]% by Weight [CALC]Chloride 0.0040 03/07/24 03/07/24 ND Cal Test 422mg/kg B4C0115Chloride40 03/01/24 03/07/24 pH 03/01/24 03/05/24B4C01150.106.2 Cal Test 643pH Units ND [CALC]% by Weight [CALC]Sulfate as SO4 0.0040 03/07/24 03/07/24 ND Cal Test 417mg/kg B4C0115Sulfate as SO4 40 03/01/24 03/07/24 Notes and Definitions DUP1 A high RPD was observed between a sample and this sample's duplicate. Analyte NOT DETECTED at or above the reporting limitND Modified preparation by pulverizing sample to pass #40 sieve and soaked for a minimum of 12 hours using a minimum dilution ratio of 1:10PREP mg/kg milligrams per kilogram (parts per million concentration units) Moore Twining Associates, Inc.The results in this report apply to the samples analyzed in accordance with the chain of custody document. This analytical report must be reproduced in its entirety.Danielle Abrames, Director of Analytical Chemistry Page 3 of 5 CHAIN OF CUSTODY / ANALYSIS REQUEST MpORE TWINING i 2527 FRESNO STREET • FRESNO, CA 93721 PHONE (559) 268-7021 FAX: (559) 268-0740 ANALYTICAL CHEMISTRY DIVISION WORKORDER#: o� CALIFORNIA FLAP CERTIFICATION # 1371 PAGE 01 OF REPORTING: REPORT TO: ❑INVOICE TO: ❑REPORT COPY TO: ❑. STANDARD FORMAT ❑ PDF ATTENTION: ATTENTION: ❑ EDT (SWRCB) ❑ EXCEL A.V ❑ GEOTRACKER/COELT(LUFT) COMPANY NAME: COMPANY NAME: GLOBAL ID: Geotechnical Division ❑ COUNTY ENVIRONMENTAL HEALTH: ADDRESS: ADDRESS: ❑ STATE WATER RESOURCES CONTROL BOARD: PHONE: PHONE: ❑OTHER: ......... .... _.__ SOLID: SAMPLED BY (PRINT): BS - BIOSOLID CR - CERAMIC SIGNATURE: SL - SOIL/SOLID LIQUID: DW - DRINKING WATER ❑ PUBLIC SYSTEM 9 ROUTINE GW - GROUNDWATER ❑ PRIVATE WELL ❑ REPEAT OL - OIL ❑ OTHER ❑ REPLACEMENT SF - SURFACE WATER ST - STORM WATER T WW- WASTEWATER TURN AROUND IME STANDARD fl Day TAT ❑ RUSH, DUE ON: NOTES ON RECEIVED CONDITION: L ❑ CUSTODY SEAL(S) BROKEN ❑ SAMPLES(S) DAMAGED A B ❑ ON ICE ❑AMBIENT TEMP. ❑INCORRECT PRESERVATIO U S E CI IReIT SAMPLE ID DATE TIME TP-390-3.5 2-8-24 CONTRACT / Proposed Circle K PROJECT NUMBER: G28867.01 PROJECT MANAGER: AV N � N � ca O 2 TYPE n N U SL x x x ANALYSIS REQUESTED � COMPANY RELINQUISHED BY COMPANY DATE TIME RECEI ED BY _ j J uent nces am Payment for services es and d ias noted nterest spec fled herein re MTA'�s currenit Stahin 30 days from ndard Terms and the dote invConditions for Labofratory Service snot so poi , aTheupersonnt osigning for the Client/Compannces are deemed delinquent, y alcknowledgeas that they arel ecitthe� monthly service charges the onlr as authorized agent to bound oh eClient, thot 'shcuCelnt toms and conditions con ebe obtained tbyrcontactingleour occ1ounhing deportment of (559)ain of Custody and e268 02es to A's terms and conditions for laboratory services ' FL-SC-0005-04 A ANALYSIS REQUESTED � COMPANY RELINQUISHED BY COMPANY DATE TIME RECEI ED BY _ j J uent nces am Payment for services es and d ias noted nterest spec fled herein re MTA'�s currenit Stahin 30 days from ndard Terms and the dote invConditions for Labofratory Service snot so poi , aTheupersonnt osigning for the Client/Compannces are deemed delinquent, y alcknowledgeas that they arel ecitthe� monthly service charges the onlr as authorized agent to bound oh eClient, thot 'shcuCelnt toms and conditions con ebe obtained tbyrcontactingleour occ1ounhing deportment of (559)ain of Custody and e268 02es to A's terms and conditions for laboratory services ' FL-SC-0005-04 A 1 O U _ , - I— � z !1 � 1 •.� •CLn t -- U p I I 0 O _ t T aJ N I Co0 - — ,n •T i > QU--------- y m o v O C ra ai `�^ c~ cL > O d m C:0 z z z 0 o c U aj �- U N iN.+ aF v u a) Y •~ � ca v r6� rn o t m Y Nv v : 11 L ° Q• W) 7 C 0 rw ra O > C !o E ra 'N i a1 ra Cu O p C N a) •� U N O o rYo N O -0 — m > aj aJ N fa ' � " in 7 -p m U aJ aJ Cr 0 v \ \ < z z 0 0 0 4— z z 0 v a, a, CLO U > ru U e( d C :ajc O > U u E ai a N � 0 N E aJ C p u r I v aJ O N U m C ~ � -0 rco v m rn > r 01 ai u c u v m d v o a CU '� a, ) a) � C N O O 3 CO -C n: � m V E C V) � += u v pc`� a;oo o N� 0 3 Y v> E ": m` v aJ rn bD N 3 v L a p a Q l7 l7 oN c= 1 m c ai tA C p `� N Q) (D a1 O a Q 2 N m m m U Q 0> m ra o-0 N a1 N 2 t N -� 7 U ro Q U r �7 u v v CL c f E,n z = mQ a== N 00\u v c �� w u Y E E U ra cv aJ aJ aJ CO O O 0 N N N 0 7 .0 aJ ro ' r�o ° O �' " O O O 1O N^ z U N m O Om ro ro ra t S Y p O ho U �? U a- p p m Z Z U D S 2 S 2 Z Z Z Z Z I- Z O U J d p cn rn ojul :)O:) panla�a}l saliof! LL LL LLIL a L dL" - 3ilds ao 1311H s1Uawwo3 L G28867.01 APPENDIX D SITE PHOTOGRAPHS G28867.01 Appendix D - Photographs Page D-1 View of the eastern portion of the project site – looking south. View of Existing mature trees in the northern portion of the project site – looking west. G28867.01 Appendix D - Photographs Page D-2 View of the southwestern edge of the project stie – looking northwest. View of the northwestern portion of the project site – looking east. G28867.01 Appendix D - Photographs Page D-3 View of the access way cleared at the north end of the project site – looking south. View of the northwestern portion of the project site – looking southeast. G28867.01 Appendix D - Photographs Page D-4 View of the well graded gravels and cobble observed in test pit TP-1 at depth of about 4 feet. View of the top soils observed in test pit TP-2. G28867.01 Appendix D - Photographs Page D-5 View of top soils and the high root content in test pit TP-7. G28867.01 Appendix D - Photographs Page D-6 View of top soils, roots, and underlying gravel with sand at test pit TP-4. View of the excavated gravels with cobble and boulders at test pit TP-4. Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Appendix G: SWPPP Construction Stormwater General Permit (CSWGP) Stormwater Pollution Prevention Plan (SWPPP) for Circle K Stores, Inc. – 9548 Killion Road SE, Yelm WA 98597 Prepared for: Department of Ecology Northwest Region - Bellevue Office Permittee / Owner Developer Operator / Contractor Circle K Stores, Inc.Circle K Stores, Inc.TBD Certified Erosion and Sediment Control Lead (CESCL) Name Organization Contact Phone Number TBD TBD TBD SWPPP Prepared By Name Organization Contact Phone Number Liz Willmot Kimley-Horn and Associates, Inc. (206) 677-8610 SWPPP Preparation Date 10/31/2024 Project Construction Dates Activity / Phase Start Date End Date Construction 06/23/2025 01/05/2026 Table of Contents Project Information (1.0) .................................................................................................................................................... 5 Existing Conditions (1.1) ............................................................................................................................................... 5 Proposed Construction Activities (1.2) ....................................................................................................................... 6 Construction Stormwater Best Management Practices (BMPs) (2.0) ......................................................................... 7 The 12 Elements (2.1) ..................................................................................................................................................... 7 Element 1: Preserve Vegetation / Mark Clearing Limits (2.1.1) .......................................................................... 7 Element 2: Establish Construction Access (2.1.2) ............................................................................................... 8 Element 3: Control Flow Rates (2.1.3) .................................................................................................................... 9 Element 4: Install Sediment Controls (2.1.4) ........................................................................................................10 Element 5: Stabilize Soils (2.1.5) ............................................................................................................................11 Element 6: Protect Slopes (2.1.6) ...........................................................................................................................12 Element 7: Protect Drain Inlets (2.1.7) ...................................................................................................................12 Element 8: Stabilize Channels and Outlets (2.1.8) ...............................................................................................13 Element 9: Control Pollutants (2.1.9) .....................................................................................................................13 Element 10: Control Dewatering (2.1.10) ...............................................................................................................18 Element 11: Maintain BMPs (2.1.11) .......................................................................................................................19 Element 12: Manage the Project (2.1.12) ...............................................................................................................20 Element 13: Protect Low Impact Development (LID) BMPs (2.1.13) .................................................................23 Pollution Prevention Team (3.0).......................................................................................................................................23 Monitoring and Sampling Requirements (4.0) ...............................................................................................................24 Site Inspection (4.1) ..................................................................................................................................................24 Stormwater Quality Sampling (4.2) .............................................................................................................................24 Turbidity Sampling (4.2.1)........................................................................................................................................24 pH Sampling (4.2.2)...................................................................................................................................................25 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies (5.0) ......................................................27 303(d) Listed Waterbodies (5.1)...................................................................................................................................27 TMDL Waterbodies (5.2) ...............................................................................................................................................27 Reporting and Record Keeping (6.0)...............................................................................................................................28 Record Keeping (6.1) ....................................................................................................................................................28 Site Log Book (6.1.1) ................................................................................................................................................28 Records Retention (6.1.2) ........................................................................................................................................28 Updating the SWPPP (6.1.3) ....................................................................................................................................28 Reporting (6.2) ...............................................................................................................................................................28 Discharge Monitoring Reports (6.2.1) ....................................................................................................................28 Notification of Noncompliance (6.2.2) ...................................................................................................................29 List of Appendices A. Site Map B. BMP Detail C. Correspondence D. Site Inspection Form E. Construction Stormwater General Permit (CSWGP) F. 303(d) List Waterbodies / TMDL Waterbodies Information G. Contaminated Site Information H. Engineering Calculations List of Acronyms and Abbreviations Acronym / Abbreviation Explanation 303(d)Section of the Clean Water Act pertaining to Impaired Waterbodies BFO Bellingham Field Office of the Department of Ecology BMP(s)Best Management Practice(s) CESCL Certified Erosion and Sediment Control Lead CO2 Carbon Dioxide CRO Central Regional Office of the Department of Ecology CSWGP Construction Stormwater General Permit CWA Clean Water Act DMR Discharge Monitoring Report DO Dissolved Oxygen Ecology Washington State Department of Ecology EPA United States Environmental Protection Agency ERO Eastern Regional Office of the Department of Ecology ERTS Environmental Report Tracking System ESC Erosion and Sediment Control GULD General Use Level Designation NPDES National Pollutant Discharge Elimination System NTU Nephelometric Turbidity Units NWRO Northwest Regional Office of the Department of Ecology pH Power of Hydrogen RCW Revised Code of Washington SPCC Spill Prevention, Control, and Countermeasure su Standard Units SWMMEW Stormwater Management Manual for Eastern Washington SWMMWW Stormwater Management Manual for Western Washington SWPPP Stormwater Pollution Prevention Plan TESC Temporary Erosion and Sediment Control SWRO Southwest Regional Office of the Department of Ecology TMDL Total Maximum Daily Load VFO Vancouver Field Office of the Department of Ecology WAC Washington Administrative Code WSDOT Washington Department of Transportation WWHM Western Washington Hydrology Model Project Information (1.0) Project/Site Name: Circle K Yelm Street/Location: 9548 Killion Road SE City: Yelm State: WA Zip code: 98597 Receiving waterbody: Proposed infiltrating stormwater basins to the Northwest and Southeast on the site; site is located within the Nisqually watershed. Existing Conditions (1.1) Total acreage (including support activities such as off-site equipment staging yards, material storage areas, borrow areas). Total acreage: 2.25 acres Disturbed acreage: 2.25 AC Existing structures: There are no existing structures on site. Landscape topography: The site is currently vacant land. The site is relatively flat, with the Southeastern part of the site about 5 feet higher than the Northwestern area of the site. Drainage patterns: Runoff flows across the site as sheet flow from the Western side of the property boundary line to the Southeastern. The area of the site along the existing road frontage drains towards the street to the existing storm drain system. Existing Vegetation: The site is surrounded by existing trees on the Northwest side, many of which will need to be removed. There are grasses, low shrubs, and scattered trees throughout the site. Critical Areas (wetlands, streams, high erosion risk, steep or difficult to stabilize slopes): The site is not within any critical areas. List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the receiving waterbody: There are no known impairments or TMDL for the receiving waterbody. Table 1 includes a list of suspected and/or known contaminants associated with the construction activity. Table 1 – Summary of Site Pollutant Constituents Constituent (Pollutant)Location Depth Concentration N/A Proposed Construction Activities (1.2) Description of site development (example: subdivision): This project proposes the construction of a 5,200 SF convenience store building, canopy and equipment, parking, signage, landscaping, and associated infrastructure. Description of construction activities (example: site preparation, demolition, excavation): Clearing and grubbing to install the appropriate temporary erosion control and sediment control measures. The site will be regraded for roads, building foundation, and utility location. Construction of vertical structures and associated utilities, addition of landscape and corresponding structures. Description of site drainage including flow from and onto adjacent properties. Must be consistent with Site Map in Appendix A: The proposed site will drain into the two bioretention ponds for the site to be fully infiltrating. Description of final stabilization (example: extent of revegetation, paving, landscaping): Final stabilization to include paving over the majority of the disturbed areas, two stormwater retention ponds, with seeding/sodding/landscaping on the remainder. Contaminated Site Information: Proposed activities regarding contaminated soils or groundwater (example: on-site treatment system, authorized sanitary sewer discharge): There are no known contaminants onsite. Construction Stormwater Best Management Practices (BMPs) (2.0) The SWPPP is a living document reflecting current conditions and changes throughout the life of the project. These changes may be informal (i.e. hand-written notes and deletions). Update the SWPPP when the CESCL has noted a deficiency in BMPs or deviation from original design. The 12 Elements (2.1) Element 1: Preserve Vegetation / Mark Clearing Limits (2.1.1) To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. Trees that are to be preserved, as well as all sensitive areas and their buffers, shall be clearly delineated, both in the field and on the plans. In general, natural vegetation and native topsoil shall be retained in an undisturbed state to the maximum extent possible. The BMP relevant to marking the clearing limits and preserving vegetation that will be applied for this project include the following: List and describe BMPs: - Silt Fence (BMP C233) o Silt fencing shall be used where delineated on the Temporary Erosion and Sediment Control Plan (TESC) to control sediment flow offsite throughout the construction process. - Tree Retention and Tree Planting (BMP T5.16) o Existing tree roots, trunks, and canopies will be fenced and protected to the maximum extents feasible during the construction activities. - Preserving Natural Vegetation (BMP C101) o Protect the trees around the site to the maximum extents feasible with fencing. Installation Schedules: These BMPs will be installed prior to demolition and construction activities. Inspection and Maintenance plan: All fencing is to be inspected at the end of each day’s work and repaired if found to be noncompliant with the conditions specified in BMP standards. Responsible Staff: Certified Erosion and Sediment Control Lead Element 2: Establish Construction Access (2.1.2) Construction access or activities occurring on unpaved areas shall be minimized, yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads. Street sweeping and street cleaning shall be employed where necessary to prevent sediment from entering state waters. All wash wastewater shall be controlled onsite. The specific BMPs related to establishing construction access that will be used on this project are as follows: List and describe BMPs: - Stabilized Construction Access (BMP C105) o The construction access entrance will be constructed per City of Vancouver detail E-105. Vehicles and construction equipment will be required to travel the full length of the stabilized construction access to reduce the amount of sediment leaving the site from the tires. Installation Schedules:Installation schedule to be determined by the General Contractor. Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day’s work. Responsible Staff:Certified Erosion and Sediment Control Lead Element 3: Control Flow Rates (2.1.3) In order to protect the properties and existing infiltrating stormwater basins onsite and downstream of the project site, stormwater discharges from the site will be controlled. The specific BMPs related to controlling that will be used on this project are as follows: Will you construct stormwater retention and/or detention facilities? Yes No Will you use permanent infiltration ponds or other low impact development (example: rain gardens, bio-retention, porous pavement) to control flow during construction? Yes No List and describe BMPs: - Wattles (BMP C235) o Wattles, per City of Vancouver (E-2.35), shall be installed at the ends of the southeast and northwest infiltration pond before the catch basins as shown on the TESC Plan to reduce the velocity of sheet runoff. - Sediment Trap (BMP C240) o Temporary sediment traps will be installed, per Department of Ecology Figure II- 3.27, where delineated in the TESC Plan to collect and store sediment during construction. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day’s work. Responsible Staff: Certified Erosion and Sediment Control Lead Element 4: Install Sediment Controls (2.1.4) All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharge to a detention facility. The specific BMPs to be used for controlling sediment on this project are as follows: List and describe BMPs: - Silt Fence (BMP C233) o During site development phase, silt fence installed per the Washington State Department of Ecology for Western Washington (E-2.33) will be used along the downhill perimeter of the project to prevent sediment from leaving the site. o During the building/vertical phase, sediment control will not be necessary on all building bearing pads, as many are flat with well-established grass cover. The rest of the landscaped areas and onsite pavements will surface drain to the infiltration basins. Temporary stabilized lots with slope, or less well-established grass cover will be inspected during wet weather conditions and, if required, silt fence may be used as a sediment control. Before removing vegetation on the lots, silt fence will be installed as a sediment control behind curb. - Wattles (BMP C235) o Wattles, per Washington State Department of Ecology for Western Washington (E-2.35), shall be installed at the ends of the southeast and northwest infiltration pond before the catch basins as shown on the TESC Plan to reduce the velocity of sheet runoff. - Sediment Trap (BMP C240) o Temporary sediment traps will be installed, per Department of Ecology Figure II- 3.27, where delineated in the TESC Plan to collect and store sediment during construction. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day’s work. Responsible Staff: Certified Erosion Control and Sediment Control Lead Element 5: Stabilize Soils (2.1.5) West of the Cascade Mountains Crest Season Dates Number of Days Soils Can be Left Exposed During the Dry Season May 1 – September 30 7 days During the Wet Season October 1 – April 30 2 days Soils must be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. Anticipated project dates:Start date: 06/23/2025 End date: 01/05/2026 Will you construct during the wet season? Yes No List and describe BMPs: - Inlet Protection (BMP C220) o Catch basins and storm drain inlets shown on the TESC Plan will have protection per Washington State Department of Ecology for Western Washington E-2.20a. This will prevent coarse sediment from entering the drainage system prior to permanent stabilization of the disturbed drainage area. o In addition, sediment will be removed from paved areas in and adjacent to construction work areas manually or using a mechanical sweeper, as needed to minimize tracking of sediments on vehicle tires away from the site and to minimize the transmission of sediments from adjacent streets in runoff. - Dust Control (BMP C140) o During grading phase of the project, dust control will be installed to prevent wind erosion. - Temporary and Permanent Seeding (BMP C120) o Following final or fine grading activity in the rear and side yards, permanent seeding shall be placed on exposed soil to provide permanent erosion protection. - Sodding (BMP C124) o Following final or fine grading activity in the front yard, sod shall be placed on exposed soil to provide permanent and immediate erosion protection. - Plastic Covering (BMP C123) o Cover cut and fill slopes and stockpiles for short durations to provide erosion protection. - Mulching (BMP C121) o Provide mulching soils as temporary protections from erosion and to assist in plant development. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day’s work. Responsible Staff: Certified Erosion and Sediment Control Lead Element 6: Protect Slopes (2.1.6) Will steep slopes be present at the site during construction? Yes No List and describe BMPs: - Temporary and Permanent Seeding (BMP C120) o Following final or fine grading activity in the rear and side yards, permanent seeding shall be placed on exposed soil to provide permanent erosion protection. - Sodding (BMP C124) o Following final or fine grading activity in the front yard, sod shall be placed on exposed soil to provide permanent and immediate erosion protection. - Plastic Covering (BMP C123) o Cover cut and fill slopes and stockpiles for short durations to provide erosion protection. - Mulching (BMP C121) o Provide mulching soils as temporary protections from erosion and to assist in plant development. The site contains steep slopes only in the infiltrating bioretention basins. The existing and proposed slopes on the basins have approximately three to one slopes. All cut and fill slopes will be designed, constructed, and protected in a manner that minimizes erosion. Element 7: Protect Drain Inlets (2.1.7) Drain inlets will be protected using the following BMP methods: List and describe BMPs: - Inlet Protection (BMP C220) o Prior to construction, storm drain inlet protection will be utilized on all catch basins in the roadway along the frontage of any areas receiving stormwater from construction activities within the permitted area. Catch basins and storm drain inlets shown on the TESC Plan will have protection per Washington State Department of Ecology for Western Washington Detail E-2.20a. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day’s work. Responsible Staff: Certified Erosion and Sediment Control Lead Element 8: Stabilize Channels and Outlets (2.1.8) As all water infiltrates onsite, there are no channels or outlets leading outside of the site and no additionally BMPs shall be installed to address Element 8. Element 9: Control Pollutants (2.1.9) All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well-organized, and free of debris. If required, BMPs to be implemented to control specific sources of pollutants are discussed below. The following pollutants are anticipated to be present on-site: Table 1 - Pollutants Pollutant (and source, if applicable) Installation of sediment and erosion controls Installation of stabilized exits Vehicle tracking Clearing and grubbing operations Grading operations Exposed soils and slopes Import/export operations Utility excavation operations Landscaping operations Topsoil stripping and stockpiling Vertical Construction Concrete List and describe BMPs: Housekeeping BMPs The following sections describe the controls, including storage practices to minimize exposure of the materials to stormwater as well as spill prevention and response practices. All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Vehicles, construction equipment, and/or petroleum product storage/dispensing: o All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. Secondary containment such as drip pans will be placed under any leaking vehicles or equipment. All petroleum product storage containers will be placed in secondary containment (see spill prevention and control below). o On-site fueling tanks and petroleum product storage containers shall include secondary containment. o Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment or when vehicle/equipment leaks are observed. o In order to perform emergency repairs onsite, temporary plastic will be placed beneath and, if raining, over the vehicle. o Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Chemical storage: o Any chemicals stored in the construction areas will conform to the appropriate source control BMPs listed in Volume IV of the Ecology stormwater manual. In Western WA, all chemicals shall have cover, containment, and protection provided onsite, per BMP C153 for Material Delivery, Storage and Containment in SWMMWW 2019. o Application of agricultural chemicals, including fertilizers and pesticides, shall be conducted in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Manufacturers’ recommendations for application procedures and rates shall be followed. Concrete and grout: o Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures (BMP C151) and Sawcutting and Surfacing Pollution Prevention (BMP C152). Additionally, providing a Concrete Washout Area (BMP C154). Installation Schedules:The described BMPs will be implemented while all pollution generating materials are onsite. Inspection and Maintenance Plan:Inspection and maintenance is to take place at the end of each day's work. Responsible Staff:Certified Erosion and Sediment Control Lead Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site? TYes £No List and describe BMPs: List and describe BMPs: • Material Delivery, Storage, and Containment (BMP C153E) o Any chemicals shall have cover, containment, and protection provided on site per Material Delivery measures to prevent, reduce, or eliminate the discharge of pollutants into receiving waters. • All vehicles, equipment and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. • On-site fueling tanks and petroleum product storage containers shall include secondary containment. • Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. • In order to perform emergency repairs on site, temporary plastic will be placed beneath and, if raining, over the vehicle. Installation Schedules:To be completed by contractor. Inspection and Maintenance Plan:See Appendix B Responsible Staff:Certified Erosion and Sediment Control Lead Spill Prevention and Control BMPs Prevent or reduce the discharge of pollutants to drainage systems or watercourses from leaks and spills by reducing the chance for spills, stopping the source of spills, containing and cleaning up spills, properly disposing of spill materials, and training employees. This best management practice covers only spill prevention and control. However, Materials Delivery and Storage (BMP C153), also contains useful information, particularly on spill prevention. o To the extent that the work can be accomplished safely, spills of oil, petroleum products, and substances listed under 40 CFR parts 110,117, and 302, and sanitary and septic wastes should be contained and cleaned up immediately. o Store hazardous materials and wastes in covered containers and protect from vandalism. o Place a stockpile of spill cleanup materials where it will be readily accessible. o Train employees in spill prevention and cleanup. o Designate responsible individuals to oversee and enforce control measures. o Spills should be covered and protected from stormwater runon during rainfall to the extent that it doesn’t compromise clean up activities. o Do not bury or wash spills with water. o Store and dispose of used clean up materials, contaminated materials, and recovered spill material that is no longer suitable for the intended purpose in conformance with the provisions in applicable BMPs. o Do not allow water used for cleaning and decontamination to enter storm drains or watercourses. Collect and dispose of contaminated water in accordance WSDOE regulations. o Contain water overflow or minor water spillage and do not allow it to discharge into drainage facilities or watercourses. o Place proper storage, cleanup, and spill reporting instructions for hazardous materials stored or used on the project site in an open, conspicuous, and accessible location. o Keep waste storage areas clean, well-organized, and equipped with ample clean supplies as appropriate for the materials being stored. Perimeter controls, containment structures, covers, and liners should be repaired or replaced as needed to maintain proper function. Cleanup: o Clean up leaks and spills immediately. o Use a rag for small spills on paved surfaces, a damp mop for general cleanup, and absorbent material for larger spills. If the spilled material is hazardous, then the used cleanup materials are also hazardous and must be sent to either a certified laundry (rags) or disposed of as hazardous waste. o Never hose down or bury dry material spills. Clean up as much of the material as possible and dispose of properly. o The spill kit should include, at a minimum: § 1-Water Resistant Nylon Bag § 3-Oil Absorbent Socks 3”x 4’ § 2-Oil Absorbent Socks 3”x 10’ § 12-Oil Absorbent Pads 17”x19” § 1-Pair Splash Resistant Goggles § 3-Pair Nitrile Gloves § 10-Disposable Bags with Ties § Instructions o Spill kits will be located in areas with a high potential for spills and deployed in a manner that allows rapid access and use by contractors. Some heavy equipment may have on- board spill kits for small spills. Spill control kits will be inspected and inventoried each construction season to confirm all required items are present. Spill control kits will be inventoried after each emergency event and restocked as needed. Minor Spills: o Minor spills typically involve small quantities of oil, gasoline, paint, etc. which can be controlled at the discovery of the spill. o Contain the spread of the spill. o Use absorbent materials on small spills rather than hosing down or burying the spill. o Notify the project foreman immediately o Recover spilled materials. o Clean the contaminated area and properly dispose of contaminated materials. o If the spill occurs on paved or impermeable surfaces, clean up using "dry" methods (absorbent materials, cat litter and/or rags). Contain the spill by encircling with absorbent materials and do not let the spill spread widely. o If the spill occurs in dirt areas, immediately contain the spill by constructing an earthen dike. Dig up and properly dispose of contaminated soil. o If the spill occurs during rain, cover spill with tarps or other material to prevent contaminating runoff. Semi-Significant Spills: o Semi-significant spills still can be controlled by the first responder along with the aid of other personnel such as laborers and the foreman, etc. This response may require the cessation of all other activities. Spills should be cleaned up immediately. Significant/Hazardous Spills: o For significant or hazardous spills that cannot be controlled by personnel in the immediate vicinity, the following steps should be taken: § Notify the local emergency response by dialing 911. In addition to 911, the contractor will notify the proper City or County officials. All emergency phone numbers will be posted at the construction site. § Contact your Supervisor and the Divisional Environmental Manager. For spills of federal reportable quantities, (examples are listed below) in conformance with the requirements in 40 CFR parts 110,119, and 302, the Division Environmental Manager (DEM) will notify the National Response Center at (800) 424-8802. The DEM will notify the Department of Ecology and any other applicable agencies. o The services of a spills contractor or a Haz-Mat team should be obtained immediately. Construction personnel should not attempt to clean up until the appropriate and qualified staffs have arrived at the job site. o Notification should first be made by telephone and followed up with a written report. Other agencies which may need to be consulted include, but are not limited to, the Public Works Department, the Coast Guard, the Highway Patrol, the City/County Police Department and Department of Ecology. o Federal regulations require that any significant oil spill into a water body or onto an adjoining shoreline be reported to the National Response Center (NRC) at 800-424-8802 (24 hours). Installation Schedules:The described BMPs will be implemented while all pollution generating materials are onsite. Inspection and Maintenance Plan:Inspection and maintenance is to take place at the end of each day's work. Responsible Staff:Certified Erosion and Sediment Control Lead. Will wheel wash or tire bath system BMPs be used during construction? £ Yes TNo Will pH-modifying sources be present on-site? T Yes £ No Table 2 - pH Modifying Sources £None T Bulk cement £Cement kiln dust £Fly ash T Other cementitious materials T New concrete washing or curing waters T Waste streams generated from concrete grinding and sawing £Exposed aggregate processes £Dewatering concrete vaults £Concrete pumping and mixer washout waters £Recycled concrete £Other (i.e. calcium lignosulfate) [please describe] List and describe BMPs: · Sawcutting and Surfacing Pollution Prevention (BMP C152) o Sawcutting and surfacing operations generate slurry and process water that contains fine particles and high pH (concrete cutting). · Concrete Washout Area (BMP C154) o Conducting washout off-site/in designated areas on-site to prevent discharge of pollutants Installation Schedules:The described BMPs will be implemented while all pollution generating materials are onsite. Inspection and Maintenance Plan:Inspection and maintenance is to take place at the end of each day's work. Responsible Staff:Certified Erosion and Sediment Control Lead. Concrete trucks must not be washed out onto the ground, or into storm drains, open ditches, streets, or streams. Excess concrete must not be dumped on-site, except in designated concrete washout areas with appropriate BMPs installed. Element 10: Control Dewatering (2.1.10) Table 4 – Dewatering BMPs T Infiltration Transport off-site in a vehicle (vacuum truck for legal disposal) Ecology-approved on-site chemical treatment or other suitable treatment technologies Sanitary or combined sewer discharge with local sewer district approval (last resort) Use of sedimentation bag with discharge to ditch or swale (small volumes of localized dewatering) Installation Schedules:The described BMPs will be implemented while all pollution generating materials are onsite. Inspection and Maintenance Plan:Inspection and maintenance is to take place at the end of each day's work. Responsible Staff:Certified Erosion and Sediment Control Lead Element 11: Maintain BMPs (2.1.11) All temporary and permanent Erosion and Sediment Control (ESC) BMPs shall be maintained and repaired as needed to ensure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMP specification (see Volume II of the SWMMWW or Chapter 7 of the SWMMEW). Visual monitoring of all BMPs installed at the site will be conducted at least once every calendar week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes inactive and is temporarily stabilized, the inspection frequency may be reduced to once every calendar month. All temporary ESC BMPs shall be removed within 30 days after final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be stabilized on-site or removed. Disturbed soil resulting from removal of either BMPs or vegetation shall be permanently stabilized. Additionally, protection must be provided for all BMPs installed for the permanent control of stormwater from sediment and compaction. BMPs that are to remain in place following completion of construction shall be examined and restored to full operating condition. If sediment enters these BMPs during construction, the sediment shall be removed and the facility shall be returned to conditions specified in the construction documents. Element 12: Manage the Project (2.1.12) The project will be managed based on the following principles: · Projects will be phased to the maximum extent practicable and seasonal work limitations will be taken into account. · Inspection and monitoring: o Inspection, maintenance and repair of all BMPs will occur as needed to ensure performance of their intended function. o Site inspections and monitoring will be conducted in accordance with Special Condition S4 of the CSWGP. Sampling locations are indicated on the Site Map. Sampling station(s) are located in accordance with applicable requirements of the CSWGP. · Maintain an updated SWPPP. o The SWPPP will be updated, maintained, and implemented in accordance with Special Conditions S3, S4, and S9 of the CSWGP. As site work progresses the SWPPP will be modified routinely to reflect changing site conditions. The SWPPP will be reviewed monthly to ensure the content is current. Table 5 – Management T Design the project to fit the existing topography, soils, and drainage patterns T Emphasize erosion control rather than sediment control T Minimize the extent and duration of the area exposed T Keep runoff velocities low T Retain sediment on-site T Thoroughly monitor site and maintain all ESC measures T Schedule major earthwork during the dry season Other (please describe) Table 6 – BMP Implementation Schedule Phase of Construction Project Stormwater BMPs Date Wet/Dry Season [Insert construction activity] [Insert BMP][MM/DD/YYYY][Insert Season] Phase of Construction Project Stormwater BMPs Date Wet/Dry Season [Insert construction activity] [Insert BMP][MM/DD/YYYY][Insert Season] Element 13: Protect Low Impact Development (LID) BMPs (2.1.13) List and describe BMPs: - Post-Construction Soil Quality and Depth (BMP T5.13) o Establish quality soil to adequate depth to enable greater stormwater functions and increased pollutant and sediment filtration within the soil thereby reducing the overall pollution. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day’s work. Responsible Staff: Certified Erosion and Sediment Control Lead Pollution Prevention Team (3.0) Table 7 – Team Information Title Name(s)Phone Number Certified Erosion and Sediment Control Lead (CESCL) TBD Resident Engineer Emergency Ecology Contact Emergency Permittee/ Owner Contact Non-Emergency Owner Contact Monitoring Personnel CESCL – see above Ecology Regional Office Southwest Region – Vancouver Office 360-690-7171 Monitoring and Sampling Requirements (4.0) Monitoring includes visual inspection, sampling for water quality parameters of concern, and documentation of the inspection and sampling findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: · A record of the implementation of the SWPPP and other permit requirements · Site inspections · Stormwater sampling data Create your own Site Inspection Form or use the Construction Stormwater Site Inspection Form found on Ecology’s website.https://www.ecology.wa.gov/Regulations-Permits/Permits- certifications/Stormwater-general-permits/Construction-stormwater-permit The site log book must be maintained on-site within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. Numeric effluent limits may be required for certain discharges to 303(d) listed waterbodies. See CSWGP Special Condition S8 and Section 5 of this template. Site Inspection (4.1) Site inspections will be conducted at least once every calendar week and within 24 hours following any discharge from the site. For sites that are temporarily stabilized and inactive, the required frequency is reduced to once per calendar month. The discharge point(s) are indicated on the Site Map (see Appendix A) and in accordance with the applicable requirements of the CSWGP. Stormwater Quality Sampling (4.2) Turbidity Sampling (4.2.1) Requirements include calibrated turbidity meter or transparency tube to sample site discharges for compliance with the CSWGP. Sampling will be conducted at all discharge points at least once per calendar week. Method for sampling turbidity: Table 8 – Turbidity Sampling Method Turbidity Meter/Turbidimeter (required for disturbances 5 acres or greater in size) T Transparency Tube (option for disturbances less than 1 acre and up to 5 acres in size) The benchmark for turbidity value is 25 nephelometric turbidity units (NTU) and a transparency less than 33 centimeters. If the discharge’s turbidity is 26 to 249 NTU or the transparency is less than 33 cm but equal to or greater than 6 cm, the following steps will be conducted: 1. Review the SWPPP for compliance with Special Condition S9. Make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. 3. Document BMP implementation and maintenance in the site log book. If the turbidity exceeds 250 NTU or the transparency is 6 cm or less at any time, the following steps will be conducted: 1. Telephone or submit an electronic report to the applicable Ecology Region’s Environmental Report Tracking System (ERTS) within 24 hours. https://www.ecology.wa.gov/About-us/Get-involved/Report-an-environmental-issue · Central Region (Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, Yakima): (509) 575-2490 · Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400 · Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish, Whatcom): (425) 649-7000 · Southwest Region (Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, Wahkiakum,): (360) 407-6300 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period 3. Document BMP implementation and maintenance in the site log book. 4. Continue to sample discharges daily until one of the following is true: · Turbidity is 25 NTU (or lower). · Transparency is 33 cm (or greater). · Compliance with the water quality limit for turbidity is achieved. o 1 - 5 NTU over background turbidity, if background is less than 50 NTU o 1% - 10% over background turbidity, if background is 50 NTU or greater · The discharge stops or is eliminated. pH Sampling (4.2.2) pH monitoring is required for “Significant concrete work” (i.e. greater than 1000 cubic yards poured concrete or recycled concrete over the life of the project).The use of engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD] or fly ash) also requires pH monitoring. For significant concrete work, pH sampling will start the first day concrete is poured and continue until it is cured, typically three (3) weeks after the last pour. For engineered soils and recycled concrete, pH sampling begins when engineered soils or recycled concrete are first exposed to precipitation and continues until the area is fully stabilized. If the measured pH is 8.5 or greater, the following measures will be taken: 1. Prevent high pH water from entering storm sewer systems or surface water. 2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate technology such as carbon dioxide (CO2) sparging (liquid or dry ice). 3. Written approval will be obtained from Ecology prior to the use of chemical treatment other than CO2 sparging or dry ice. Method for sampling pH: Table 8 – pH Sampling Method T pH meter pH test kit Wide range pH indicator paper Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies (5.0) The site is located within the Nisqually watershed, and there are no adjacent waterbodies that are listed in the 303(d) (Category 5). 303(d) Listed Waterbodies (5.1) Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH? Yes No TMDL Waterbodies (5.2) Waste Load Allocation for CWSGP Discharges: N/A Discharges to TMDL receiving waterbodies will meet in-stream water quality criteria at the point of discharge. The Construction Stormwater General Permit Proposed New Discharge to an Impaired Water Body form is included in Appendix F. Reporting and Record Keeping (6.0) Record Keeping (6.1) Site Log Book (6.1.1) A site log book will be maintained for all on-site construction activities and will include: · A record of the implementation of the SWPPP and other permit requirements · Site inspections · Sample logs Records Retention (6.1.2) Records will be retained during the life of the project and for a minimum of three (3) years following the termination of permit coverage in accordance with Special Condition S5.C of the CSWGP. Permit documentation to be retained on-site: · CSWGP · Permit Coverage Letter · SWPPP · Site Log Book Permit documentation will be provided within 14 days of receipt of a written request from Ecology. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with Special Condition S5.G.2.b of the CSWGP. Updating the SWPPP (6.1.3) The SWPPP will be modified if: · Found ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. · There is a change in design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the State. The SWPPP will be modified within seven (7) days if inspection(s) or investigation(s) determine additional or modified BMPs are necessary for compliance. An updated timeline for BMP implementation will be prepared. Reporting (6.2) Discharge Monitoring Reports (6.2.1) Cumulative soil disturbance is one (1) acre or larger; therefore, Discharge Monitoring Reports (DMRs) will be submitted to Ecology monthly. If there was no discharge during a given monitoring period the DMR will be submitted as required, reporting “No Discharge”. The DMR due date is fifteen (15) days following the end of each calendar month. DMRs will be reported online through Ecology’s WQWebDMR System. Notification of Noncompliance (6.2.2) If any of the terms and conditions of the permit is not met, and the resulting noncompliance may cause a threat to human health or the environment, the following actions will be taken: 1. Ecology will be notified within 24-hours of the failure to comply by calling the applicable Regional office ERTS phone number (Regional office numbers listed below). 2. Immediate action will be taken to prevent the discharge/pollution or otherwise stop or correct the noncompliance. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days, unless requested earlier by Ecology. Anytime turbidity sampling indicates turbidity is 250 NTUs or greater, or water transparency is 6 cm or less, the Ecology Regional office will be notified by phone within 24 hours of analysis as required by Special Condition S5.A of the CSWGP. · Central Region at (509) 575-2490 for Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, or Yakima County · Eastern Region at (509) 329-3400 for Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, or Whitman County · Northwest Region at (425) 649-7000 for Island, King, Kitsap, San Juan, Skagit, Snohomish, or Whatcom County · Southwest Region at (360) 407-6300 for Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, or Wahkiakum Include the following information: 1. Your name and Phone number 2. Permit number 3. City / County of project 4. Sample results 5. Date / Time of call 6. Date / Time of sample 7. Project name In accordance with Special Condition S4.D.5.b of the CSWGP, the Ecology Regional office will be notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH water. Appendix/Glossary A. Site Map K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) S47 ° 0 4 ' 2 9 " W 87.3 ' N88°15'36"W 399.0' SF SF SF SF SF SF SF SF SF SF SF SF SF SF SF S F S F S F SF S F S F S F S F S F S F S F S F S F S F SF SF SF SF SF SF SF SF SF LIMITS OF DISTURBANCE TOP OF POND ELEV: 350.00 BOTTOM OF POND ELEV: 346.50 MAXIMUM SIDE SLOPES 3H:1V ER O S I O N & SE D I M E N T C O N T R O L PL A N C3.0 NORTH © CI R C L E K - Y E L M & KI L L O N PR E P A R E D F O R CI R C L E K S T O R E S , I N C . PR E L I M I N A R Y , N O T FO R C O N S T R U C T I O N SF SF SF ESC STANDARD PLAN NOTES SUMMARY DESCRIPTION OF ESC BMP'S UTILIZED LEGEND ESC STANDARD PLAN NOTES SF SF SF GENERAL ESC NOTES SUMMARY DESCRIPTION OF ESC BMP'S UTILIZED LEGEND ER O S I O N & SE D I M E N T C O N T R O L DE T A I L S C3.1 © CI R C L E K - Y E L M & KI L L O N PR E P A R E D F O R CI R C L E K S T O R E S , I N C . PR E L I M I N A R Y , N O T FO R C O N S T R U C T I O N K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) (ACCESS ROAD) 113' CA N O P Y ℄ BL D G . ℄ TRANSFORMER PAD (APPROX) W EXCAVATION HOLE 12 K D I E S E L ( 1 0 ' D I A . ) 8K CK CHOICE12K SUL 20K REGULAR S47 ° 0 4 ' 2 9 " W 87.3 ' N88°15'36"W 399.0' 11.1' 11.0'5.0'9.5' (TYP) 5.0' 28.0' (TYP) 6.0' 20.0' 45.0' 24.0' 12.0'10.5' 5.0' 7.5' 36.5' 11.1' 50.0' 5.0' 12.0' 55.0' 43.5' 5.0' 6.0' 55.0' 6.0' (TYP) 13.7' 10.3' 36.0' 15.5' 34.0' 14.0' 26.0' 8.3'87.1' 36.1' 49.8' 12.0' R10.0' R3.0' R3.0' (TYP) R3.0' R10.0'R10.0'R25.0' R30.0' R10.0' R46.0' R45.0' 40.0' 21.0' 40.0' 95.3' 5556 SI T E P L A N C4.0 NORTH © CI R C L E K - Y E L M & KI L L O N PR E P A R E D F O R CI R C L E K S T O R E S , I N C . PR E L I M I N A R Y , N O T FO R C O N S T R U C T I O N # LEGEND PARKING / SITE DATA THURSTON COUNTY 21 SPACES 1 SPACE 21 SPACES 1 SPACE REQUIRED PROVIDED N/A 44.7% 1.30 AC ±5,200 SF 102,366 SF / 2.35 AC FUELING STATION WITH CONVENIENCE STORE C-1 5%N/A N/A 4 CONSTRUCTION NOTES Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) Y E L M A V E N U E / S R 5 1 0 ( M I N O R A R T E R I A L ) > > > >>>>>>> > > > S47 ° 0 4 ' 2 9 " W 87.3 ' N88°15'36"W C5 . 2 1 BIORETENTION 1 BOTTOM AREA: 1,098 SF BOTTOM ELEV: 346.00 TOP ELEV: 349.50 SIDE SLOPE: 3:1 350.91 SW 350.85 TC 350.35 BC 351.02 TC 350.52 BC 352.13 TC 351.63 BC 352.49 TC 351.99 BC 352.56 TC 352.06 BC 352.90 TC 352.40 BC 353.20 TC 352.70 BC 353.35 TC 352.85 BC 353.76 TC 353.26 BC 353.19 SW 353.07 SW 353.46 SW 353.29 TC 352.79 BC 353.31 TC 352.81 BC 353.28 TC 352.78 BC 353.51 TC 353.01 BC 353.76 TC 353.26 BC 353.50 TC 353.00 BC 351.65 TC 351.15 BC 350.86 FL 351.55 TC 351.05 BC 351.23 TC 350.73 BC 351.31 TC 350.81 BC 350.00 FL 352.17 TC 351.67 BC 353.20 TC 352.70 BC 2.0 4 % 1.6 8 % 1.49 % 1. 7 6 % 1. 5 3 % 1 . 5 1 % 6.87 % 351.98 FL 350.83 SW 346.00 FG 126 LF OF @ 2.56% 81 LF OF @ 0.56% 8. 2 6 % 1. 7 5 % 1. 7 6 % 1.8 2 % 11 353.28 SW 353.44 SW 353.45 SW 353.36 SW 353.23 SW 7 1 13 LF OF @ 6.50% 10 10 7 33 . 0 1 % 33 . 3 3 % 33. 3 3 % 33.33% 352.35 FG 352.66 FG 353.51 TC 353.01 BC 353.48 TC 352.98 BC 353.32 TC 352.82 BC 353.20 SW 353.07 SW 353.35 SW 353.45 SW 353.18 SW 353.31 SW 351.36 TC 350.86 BC 351.36 TC 350.86 BC 351.59 FL 352.05 FL 349.50 FL 350.06 FL 351.06 TC 350.56 BC 351.08 SW ME 351.02 SW ME 350.96 TC ME 350.46 BC ME 350.75 SW 350.84 SW 350.54 ME 353.02 SW 353.07 SW 353.51 SW 2 0 . 0 ' B . S . L . 20 . 0 ' B . S . L . 15. 0 ' B . S . L . 10. 0 ' P S E EAS E M E N T 350.49 ME 1.89 % 353.13 SW 5.4 7 % 351.37 TC 350.87 BC 10 9 CB-01 RIM: 352.05 INV OUT: 349.22 CB-02 RIM: 351.59 INV OUT: 348.76 INV: 346.00 5 5 3 3 349.40 FL 1 1 1 . 6 1 % 7. 4 0 % 1 . 8 8 % 1.76 % 353.06 SW 351.21 SW ME 351.24 SW ME 351.10 TC ME 350.60 BC ME FFE = 353.50 12(TYP.) GR A D I N G P L A N C5.0 © CI R C L E K - Y E L M & KI L L O N PR E P A R E D F O R CI R C L E K S T O R E S , I N C . PR E L I M I N A R Y , N O T FO R C O N S T R U C T I O N NORTH 1950 1950 1.00% FG ME TC FFE BC 1.PRIVATE CURB RAMPS ON THE SITE (I.E. OUTSIDE PUBLIC STREET RIGHT-OF-WAY) SHALL CONFORM TO ADA STANDARDS AND SHALL HAVE A DETECTABLE WARNING SURFACE THAT IS FULL WIDTH AND FULL DEPTH OF THE CURB RAMP, NOT INCLUDING FLARES. 2.ALL ACCESSIBLE ROUTES, GENERAL SITE AND BUILDING ELEMENTS, RAMPS, CURB RAMPS, STRIPING, AND PAVEMENT MARKINGS SHALL CONFORM TO ADA STANDARDS FOR ACCESSIBLE DESIGN, LATEST EDITION. 3.BEFORE PLACING PAVEMENT, CONTRACTOR SHALL VERIFY THAT SUITABLE ACCESSIBLE PEDESTRIAN ROUTES (PER ADA AND SPOKANE COUNTY) EXIST TO AND FROM EVERY DOOR AND ALONG SIDEWALKS, ACCESSIBLE PARKING SPACES, ACCESS AISLES, AND ACCESSIBLE ROUTES. IN NO CASE SHALL AN ACCESSIBLE RAMP SLOPE EXCEED 1 VERTICAL TO 12 HORIZONTAL. IN NO CASE SHALL SIDEWALK CROSS SLOPE EXCEED 2.0 PERCENT. IN NO CASE SHALL LONGITUDINAL SIDEWALK SLOPE EXCEED 5.0 PERCENT. ACCESSIBLE PARKING SPACES AND ACCESS AISLES SHALL NOT EXCEED 2.0 PERCENT SLOPE IN ANY DIRECTION. 4.CONTRACTOR SHALL TAKE FIELD SLOPE MEASUREMENTS ON FINISHED SUBGRADE AND FORM BOARDS PRIOR TO PLACING PAVEMENT TO VERIFY THAT ADA SLOPE REQUIREMENTS ARE PROVIDED. CONTRACTOR SHALL CONTACT ENGINEER PRIOR TO PAVING IF ANY EXCESSIVE SLOPES ARE ENCOUNTERED. NO CONTRACTOR CHANGE ORDERS WILL BE ACCEPTED FOR ADA SLOPE COMPLIANCE ISSUES. 5.ALL PEDESTRIAN SIDEWALKS, PATHWAYS, AND CROSSWALKS SHALL BE CONSTRUCTED NOT TO EXCEED MAX, 2.0 PERCENT CROSS SLOPE, MAX 5.0 PERCENT RUNNING SLOPE. 6.ALL HANDICAP ACCESSIBLE PARKING SPACES SHALL BE CONSTRUCTED NOT TO EXCEED MAX 2.0 PERCENT CROSS SLOPE IN ALL DIRECTIONS. 7.PROPOSED GRADES TO MATCH EXISTING ELEVATIONS AT PROPERTY LINE. 8.CONTRACTOR TO FIELD VERIFY ELEVATIONS AT ALL EXISTING SIDEWALK AND ROAD CONNECTION POINTS WITH ENGINEER OF RECORD BEFORE CONSTRUCTION OF ANY IMPROVEMENTS. 9.FOR EROSION CONTROL NOTES REFER TO SHEET C3.0 - EROSION & SEDIMENT CONTROL PLAN. 10.CONTRACTOR TO ENSURE ADEQUATE COVER REMAINS OVER ALL EXISTING UTILITIES. 11.CONTRACTOR TO VERIFY EXISTING COVER OVER ALL UTILITIES BEFORE START OF CONSTRUCTION AND TO COORDINATE WITH THE ENGINEER OF RECORD PRIOR TO START OF CONSTRUCTION IF DESIGN DOES NOT PROVIDE 36" COVER. 12.ALL EXISTING VALVES, BOXES, MANHOLE LIDS, COVERS, AND SIMILAR APPURTENANCES MUST BE ADJUSTED ACCORDINGLY TO MATCH FINISHED GRADE. 13.MINIMUM 48" SUBGRADE INFILTRATION BENEATH 12-18" OF TREATMENT SOIL PER SECTION 6.7.1 OF THE SRSM. NOTES LEGEND MA T C H L I N E : S E E S H E E T C5 . 1 SW GRADING AND DRAINAGE NOTES 1950 K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) UGE UGE UGE UGE UG E UG E K I L L I O N R O A D S E (M A J O R C O L L E C T O R ) (ACCESS ROAD) 113' CA N O P Y ℄ BL D G . ℄ TRANSFORMER PAD (APPROX) W EXCAVATION HOLE 12 K D I E S E L ( 1 0 ' D I A . ) 8K CK CHOICE12K SUL 20K REGULAR > > > > > > > > > >>>>>>>>>>> >>>>>> N88°15'36"W 399.0' C5 . 2 2 353.76 TC 353.26 BC 353.75 TC 353.25 BC 353.50 TC 353.00 BC 353.47 TC 352.97 BC 353.60 TC 353.10 BC 353.60 TC 353.10 BC 353.76 TC 353.26 BC 353.04 FG 353.55 TC 353.05 BC 353.30 SW 353.29 SW 353.94 TC 353.44 BC 353.97 TC 353.47 BC 354.08 TC 353.58 BC 354.13 TC 353.63 BC 354.62 TC 354.12 BC 354.60 TC 354.10 BC 354.76 TC 354.26 BC 354.32 SW 355.16 SW ME 354.16 SW 354.53 TC 354.03 BC 354.16 TC 353.66 BC 353.64 TC 353.14 BC 352.83 TC 352.33 BC 351.65 TC 351.15 BC 353.05 FL 352.80 FL 1. 7 6 % 1. 5 3 % 1.1 6 % 1. 2 5 % 1.1 8 % 2.14 % 1.71 %0.97 % 1.6 8 % 1.29 % 17. 1 1 % 8. 6 9 % 345.70 FG 1.4 1 % 1.1 3 % 354.72 SW 355.18 TC 354.68 BC 354.59 TC 354.09 BC 351.98 FL 352.42 FL 2 . 2 7 % 75 LF OF @ 5.92% 353.46 SW 353.42 SW 1. 7 5 % 1.8 2 % 3 . 1 6 % 4353.44 SW 355.34 SW ME 7 4 LF OF @ 6.50% 13 LF OF @ 6.50% 19 LF OF @ 6.50% 10 10 351.64 FL 353.31 SW 353.31 SW 353.29 SW 353.29 SW 353.38 SW 353.39 SW 353.61 SW 354.29 SW 354.38 SW 352.13 TC 351.63 BC 352.16 TC 351.66 BC 353.99 TC 353.49 BC 352.38 FL 353.45 TC 352.95 BC 353.05 FG 353.31 FL 353.76 TC 353.26 BC 353.67 SW 351.97 FL 352.01 FL 353.33 SW 353.38 SW 15.0' B.S.L. 1 5 . 0 ' P S E E A S E M E N T FFE = 353.50 353.44 SW BIORETENTION 2 BOTTOM AREA: 1,199 SF BOTTOM ELEV: 345.70 TOP ELEV: 349.20 SIDE SLOPE: 3:1 11 10 10 10 10 9 9 9 9 CB-04 RIM: 352.80 INV OUT: 350.13 CB-03 RIM: 351.17 INV IN: 348.31 INV OUT: 348.31 OIL/WATER SEPARATOR RIM: 349.17 INV IN: 348.06 INV OUT: 348.06 INV: 345.70 INV: 345.70 INV: 347.78 INV: 346.92 6 5 5 4 3 4 LF OF @ 6.49% 3 3 3 2 1 349.40 FL 349.20 FL 1 1 353.92 TC 353.42 BC 355.59 FG 355.71 FG 355.28 FG 355.38 SW ME 356.09 SW ME 355.70 SW ME 33.33% 33 . 3 3 % 33 . 3 3 % 33.33% 354.84 SW ME 354.85 SW ME 354.81 TC ME 354.31 BC ME 354.30 SW ME 354.69 SW 353.78 SW ME 353.75 SW ME 354.20 TC ME 353.70 BC ME 354.12 SW ME 354.40 SW ME 354.12 SW 1 353.19 FL 354.44 FL FFE = 353.50 12 (TYP.)GR A D I N G P L A N C5.1 NORTH © CI R C L E K - Y E L M & KI L L O N PR E P A R E D F O R CI R C L E K S T O R E S , I N C . PR E L I M I N A R Y , N O T FO R C O N S T R U C T I O N 1.PRIVATE CURB RAMPS ON THE SITE (I.E. OUTSIDE PUBLIC STREET RIGHT-OF-WAY) SHALL CONFORM TO ADA STANDARDS AND SHALL HAVE A DETECTABLE WARNING SURFACE THAT IS FULL WIDTH AND FULL DEPTH OF THE CURB RAMP, NOT INCLUDING FLARES. 2.ALL ACCESSIBLE ROUTES, GENERAL SITE AND BUILDING ELEMENTS, RAMPS, CURB RAMPS, STRIPING, AND PAVEMENT MARKINGS SHALL CONFORM TO ADA STANDARDS FOR ACCESSIBLE DESIGN, LATEST EDITION. 3.BEFORE PLACING PAVEMENT, CONTRACTOR SHALL VERIFY THAT SUITABLE ACCESSIBLE PEDESTRIAN ROUTES (PER ADA AND SPOKANE COUNTY) EXIST TO AND FROM EVERY DOOR AND ALONG SIDEWALKS, ACCESSIBLE PARKING SPACES, ACCESS AISLES, AND ACCESSIBLE ROUTES. IN NO CASE SHALL AN ACCESSIBLE RAMP SLOPE EXCEED 1 VERTICAL TO 12 HORIZONTAL. IN NO CASE SHALL SIDEWALK CROSS SLOPE EXCEED 2.0 PERCENT. IN NO CASE SHALL LONGITUDINAL SIDEWALK SLOPE EXCEED 5.0 PERCENT. ACCESSIBLE PARKING SPACES AND ACCESS AISLES SHALL NOT EXCEED 2.0 PERCENT SLOPE IN ANY DIRECTION. 4.CONTRACTOR SHALL TAKE FIELD SLOPE MEASUREMENTS ON FINISHED SUBGRADE AND FORM BOARDS PRIOR TO PLACING PAVEMENT TO VERIFY THAT ADA SLOPE REQUIREMENTS ARE PROVIDED. CONTRACTOR SHALL CONTACT ENGINEER PRIOR TO PAVING IF ANY EXCESSIVE SLOPES ARE ENCOUNTERED. NO CONTRACTOR CHANGE ORDERS WILL BE ACCEPTED FOR ADA SLOPE COMPLIANCE ISSUES. 5.ALL PEDESTRIAN SIDEWALKS, PATHWAYS, AND CROSSWALKS SHALL BE CONSTRUCTED NOT TO EXCEED MAX, 2.0 PERCENT CROSS SLOPE, MAX 5.0 PERCENT RUNNING SLOPE. 6.ALL HANDICAP ACCESSIBLE PARKING SPACES SHALL BE CONSTRUCTED NOT TO EXCEED MAX 2.0 PERCENT CROSS SLOPE IN ALL DIRECTIONS. 7.PROPOSED GRADES TO MATCH EXISTING ELEVATIONS AT PROPERTY LINE. 8.CONTRACTOR TO FIELD VERIFY ELEVATIONS AT ALL EXISTING SIDEWALK AND ROAD CONNECTION POINTS WITH ENGINEER OF RECORD BEFORE CONSTRUCTION OF ANY IMPROVEMENTS. 9.FOR EROSION CONTROL NOTES REFER TO SHEET C3.0 - EROSION & SEDIMENT CONTROL PLAN. 10.CONTRACTOR TO ENSURE ADEQUATE COVER REMAINS OVER ALL EXISTING UTILITIES. 11.CONTRACTOR TO VERIFY EXISTING COVER OVER ALL UTILITIES BEFORE START OF CONSTRUCTION AND TO COORDINATE WITH THE ENGINEER OF RECORD PRIOR TO START OF CONSTRUCTION IF DESIGN DOES NOT PROVIDE 36" COVER. 12.ALL EXISTING VALVES, BOXES, MANHOLE LIDS, COVERS, AND SIMILAR APPURTENANCES MUST BE ADJUSTED ACCORDINGLY TO MATCH FINISHED GRADE. 13.MINIMUM 48" SUBGRADE INFILTRATION BENEATH 12-18" OF TREATMENT SOIL PER SECTION 6.7.1 OF THE SRSM. NOTES MA T C H L I N E : S E E S H E E T C5 . 0 1950 1950 1.00% FG ME TC FFE BC LEGEND SW 1950 GRADING AND DRAINAGE NOTES TY P I C A L D R A I N A G E CR O S S S E C T I O N S C5.2 © CI R C L E K - Y E L M & KI L L O N PR E P A R E D F O R CI R C L E K S T O R E S , I N C . PR E L I M I N A R Y , N O T FO R C O N S T R U C T I O N BIORETENTION POND 1 - WEST TO EAST PROFILE1 C5.2 NOT TO SCALE BIORETENTION BASIN 2 - EAST TO WEST PROFILE2 C5.2 NOT TO SCALE B. BMP Detail Con- struction Stormwater BMP Construction SWPPP Element # #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 II-2.2 Element 2: Establish Construction Access II-2.3 Element 3: Control Flow Rates II-2.4 Element 4: Install Sediment Controls II-2.5 Element 5: Stabilize Soils II-2.6 Element 6: Protect Slopes II-2.7 Element 7: Protect Storm Drain Inlets II-2.8 Element 8: Stabilize Channels and Outlets II-2.9 Element 9: Control Pollutants II-2.10 Element 10: Control Dewatering II-2.11 Element 11: Maintain BMPs II-2.12 Element 12: Manage the Project II-2.13 Element 13: Protect Infiltration BMPs Table II-4.1: Construction Stormwater BMPs by SWPPP Element (continued) II-4.2 Construction Source Control BMPs BMP C101: Preserving Natural Vegetation Purpose The purpose of preserving natural (or existing) vegetation is to reduce erosion wherever prac- ticable. Limiting site disturbance is the single most effective method for reducing erosion. For  example, conifers can hold up to about 50% of all rain that falls during a storm. Up to 20% to 30%  of this rain may never reach the ground but is taken up by the tree or evaporates. Another benefit  is that the rain held in the tree can be released slowly to the ground after the storm. Conditions of Use Natural vegetation should be preserved on steep slopes, near perennial and intermittent water- courses or swales, and on building sites in wooded areas.  l As required by the local jurisdiction.  l Phase construction to preserve natural vegetation on the project site for as long as possible  during the construction period. Design and Installation Specifications Natural vegetation can be preserved in natural clumps or as individual trees, shrubs and vines. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 312 The preservation of individual plants is more difficult because heavy equipment is generally used  to remove unwanted vegetation. The points to remember when attempting to save individual  plants are:  l Is the plant worth saving? Consider the location, species, size, age, vigor, and the work  involved. Local jurisdictions may also have ordinances to save natural vegetation and trees.  l Fence or clearly mark areas around trees that are to be saved. It is preferable to keep  ground disturbance away from the trees at least as far out as the dripline. Plants need protection from three kinds of injuries:  l Construction Equipment - This injury can be above or below the ground level. Damage res- ults from scarring, cutting of roots, and compaction of the soil. Placing a fenced buffer zone  around plants to be saved prior to construction can prevent construction equipment injuries.  l Grade Changes - Changing the natural ground level will alter grades, which affects the  plant's ability to obtain the necessary air, water, and minerals. Minor fills usually do not  cause problems although sensitivity between species does vary and should be checked.  Trees can typically tolerate fill of 6 inches or less. For shrubs and other plants, the fill should  be less. When there are major changes in grade, it may become necessary to supply air to the roots  of plants. This can be done by placing a layer of gravel and a tile system over the roots  before the fill is made. The tile system should be laid out on the original grade leading from  a drywell around the tree trunk. The system should then be covered with small stones to  allow air to circulate over the root area. Lowering the natural ground level can seriously damage trees and shrubs. The highest per- centage of the plant roots are in the upper 12 inches of the soil and cuts of only 2 to 3 inches  can cause serious injury. To protect the roots it may be necessary to terrace the immediate  area around the plants to be saved. If roots are exposed, construction of retaining walls  may be needed to keep the soil in place. Plants can also be preserved by leaving them on  an undisturbed, gently sloping mound. To increase the chances for survival, it is best to limit  grade changes and other soil disturbances to areas outside the dripline of the plant.  l Excavations - Protect trees and other plants when excavating for drainfields and power,  water, and/or sewer lines. Where possible, the trenches should be routed around trees and  large shrubs. When this is not possible, it is best to tunnel under them. This can be done  with hand tools or with power augers. If it is not possible to route the trench around plants to  be saved, then the following should be observed:  o Cut as few roots as possible. When you have to cut, cut clean. Paint cut root ends  with a wood dressing like asphalt base paint if roots will be exposed for more than 24  hours.  o Backfill the trench as soon as possible.  o Tunnel beneath root systems as close to the center of the main trunk to preserve  most of the important feeder roots. Some problems that can be encountered are: 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 313  l Maple, Dogwood, Red alder, Western hemlock, Western red cedar, and Douglas fir do not  readily adjust to changes in environment and special care should be taken to protect these  trees.  l The windthrow hazard of Pacific silver fir and madrona is high, while that of Western hem- lock is moderate. The danger of windthrow increases where dense stands have been  thinned. Other species (unless they are on shallow, wet soils less than 20 inches deep)  have a low windthrow hazard.  l Cottonwoods, maples, and willows have water-seeking roots. These can cause trouble in  sewer lines and infiltration fields. On the other hand, they thrive in high moisture conditions  that other trees would not.  l Thinning operations in pure or mixed stands of grand fir, Pacific silver fir, noble fir, Sitka  spruce, western red cedar, western hemlock, Pacific dogwood, and red alder can cause ser- ious disease problems. Disease can become established through damaged limbs, trunks,  roots, and freshly cut stumps. Diseased and weakened trees are also susceptible to insect  attack. Maintenance Standards Inspect flagged and/or fenced areas regularly to make sure flagging or fencing has not been  removed or damaged. If the flagging or fencing has been damaged or visibility reduced, it shall be  repaired or replaced immediately and visibility restored. If tree roots have been exposed or injured, “prune” cleanly with an appropriate pruning saw or lop- pers directly above the damaged roots and recover with native soils. Treatment of sap flowing  trees (e.g. fir, hemlock, pine, soft maples) is not advised as sap forms a natural healing barrier. BMP C102: Buffer Zones Purpose Creation of an undisturbed area or strip of natural vegetation or an established suitable planting  that will provide a living filter to reduce soil erosion and stormwater runoff velocities. Conditions of Use Buffer zones are used along streams, wetlands and other bodies of water that need protection  from erosion and sedimentation. Contractors can use vegetative buffer zone BMPs to protect nat- ural swales and they can incorporate them into the natural landscaping of an area. Do not use critical area buffer zones as sediment treatment areas. These areas shall remain com- pletely undisturbed. The local permitting authority may expand the buffer widths temporarily to  allow the use of the expanded area for removal of sediment. The types of buffer zones can change the level of protection required as shown below:  l Designated Critical Area Buffers - buffers that protect Critical Areas, as defined by the  Washington State Growth Management Act, and are established and managed by the local  2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 314 Conditions of Use To establish clearing limits, plastic, fabric, or metal fence may be used:  l At the boundary of sensitive areas, their buffers, and other areas required to be left  uncleared.  l As necessary to control vehicle access to and on the site. Design and Installation Specifications High-visibility plastic fence shall be composed of a high-density polyethylene (HDPE) material  and shall be at least four feet in height. Posts for the fencing shall be steel or wood and placed  every 6 feet on center (maximum) or as needed to ensure rigidity. The fencing shall be fastened to  the post every six inches with a polyethylene tie. On long continuous lengths of fencing, a tension  wire or rope shall be used as a top stringer to prevent sagging between posts. The fence color  shall be high-visibility orange. The fence tensile strength shall be 360 lbs/ft using the ASTM  D4595 testing method. If appropriate, install fabric silt fence in accordance with BMP C233: Silt Fence to act as high-vis- ibility fence. Silt fence shall be at least 3 feet high and must be highly visible to meet the require- ments of this BMP. Metal fences shall be designed and installed according to the manufacturer's specifications. Metal fences shall be at least 3 feet high and must be highly visible. Fences shall not be wired or stapled to trees. Maintenance Standards If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately  and visibility restored. BMP C105: Stabilized Construction Access Purpose Stabilized construction accesses are established to reduce the amount of sediment transported  onto paved roads outside the project site by vehicles or equipment. This is done by constructing a  stabilized pad of quarry spalls at entrances and exits for project sites. Conditions of Use Construction accesses shall be stabilized wherever traffic will be entering or leaving a con- struction site if paved roads or other paved areas are within 1,000 feet of the site. For residential subdivision construction sites, provide a stabilized construction access for each  residence, rather than only at the main subdivision entrance. Stabilized surfaces shall be of suf- ficient length/width to provide vehicle access/parking, based on lot size and configuration. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 316 On large commercial, highway, and road projects, the designer should include enough extra  materials in the contract to allow for additional stabilized accesses not shown in the initial Con- struction SWPPP. It is difficult to determine exactly where access to these projects will take place;  additional materials will enable the contractor to install them where needed. Design and Installation Specifications  l See Figure II-4.1: Stabilized Construction Access for details. Note: the 100’ minimum length  of the access shall be reduced to the maximum practicable size when the size or con- figuration of the site does not allow the full length (100’).  l Construct stabilized construction accesses with a 12-inch thick pad of 4-inch to 8-inch  quarry spalls, a 4-inch course of asphalt treated base (ATB), or use existing pavement. Do  not use crushed concrete, cement, or calcium chloride for construction access stabilization  because these products raise pH levels in stormwater and concrete discharge to waters of  the State is prohibited.  l A separation geotextile shall be placed under the spalls to prevent fine sediment from pump- ing up into the rock pad. The geotextile shall meet the standards listed in Table II-4.2: Stab- ilized Construction Access Geotextile Standards. Geotextile Property Required Value Grab Tensile  Strength (ASTM D4751)200  psi min. Grab Tensile  Elongation (ASTM D4632)30%  max. Mullen Burst  Strength (ASTM D3786-80a)400  psi min. AOS (ASTM D4751)No. 20 to No. 45  (U.S. standard sieve size) Table II-4.2: Stabilized Construction Access Geotextile Standards  l Consider early installation of the first lift of asphalt in areas that will be paved; this can be  used as a stabilized access. Also consider the installation of excess concrete as a sta- bilized access. During large concrete pours, excess concrete is often available for this pur- pose.  l Fencing (see BMP C103: High-Visibility Fence) shall be installed as necessary to restrict  traffic to the construction access.  l Whenever possible, the access shall be constructed on a firm, compacted subgrade. This  can substantially increase the effectiveness of the pad and reduce the need for main- tenance.  l Construction accesses should avoid crossing existing sidewalks and back of walk drains if  at all possible. If a construction access must cross a sidewalk or back of walk drain, the full  length of the sidewalk and back of walk drain must be covered and protected from sediment  leaving the site. Alternative Material Specification 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 317 WSDOT has raised safety concerns about the quarry spall rock specified above. WSDOT  observes that the 4-inch to 8-inch rock sizes can become trapped between dually truck tires, and  then released off-site at highway speeds. WSDOT has chosen to use a modified specification for  the rock while continuously verifying that the stabilized construction access remains effective. To  remain effective, the BMP must prevent sediment from migrating off site. To date, there has been  no performance testing to verify operation of this new specification. Local jurisdictions may use  the alternative specification, but must perform increased off-site inspection if they use, or allow  others to use, it. Stabilized construction accesses may use material that meets the requirements of WSDOT's  Standard Specifications for Road, Bridge, and Municipal Construction Section 9-03.9(1)  (WSDOT, 2016) for ballast except for the following special requirements. The grading and quality requirements are listed in Table II-4.3: Stabilized Construction Access  Alternative Material Requirements. Sieve Size Percent Passing 2½″99 to 100 2″65 to 100 ¾″40 to 80 No. 4 5 max. No. 100 0 to 2 % Fracture 75 min. Notes:   1. All percentages are by weight.  2. The sand equivalent value and dust ratio require- ments do not apply.  3. The fracture requirement shall be at least one  fractured face and will apply the combined  aggregate retained on the No. 4 sieve in accord- ance with FOP for AASHTO T 335. Table II-4.3: Stabilized Construction Access Alternative Material Requirements Maintenance Standards Quarry spalls shall be added if the pad is no longer in accordance with the specifications.  l If the access is not preventing sediment from being tracked onto pavement, then alternative  measures to keep the streets free of sediment shall be used. This may include replace- ment/cleaning of the existing quarry spalls, street sweeping, an increase in the dimensions  2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 318 of the access, or the installation of BMP C106: Wheel Wash.  l Any sediment that is tracked onto pavement shall be removed by shoveling or street sweep- ing. The sediment collected by sweeping shall be removed or stabilized on site. The pave- ment shall not be cleaned by washing down the street, except when sweeping is ineffective  and there is a threat to public safety. If it is necessary to wash the streets, the construction  of a small sump to contain the wash water shall be considered. The sediment would then be  washed into the sump where it can be controlled.  l Perform street sweeping by hand or with a high efficiency sweeper. Do not use a non-high  efficiency mechanical sweeper because this creates dust and throws soils into storm sys- tems or conveyance ditches.  l Any quarry spalls that are loosened from the pad, which end up on the roadway shall be  removed immediately.  l If vehicles are entering or exiting the site at points other than the construction access(es),  BMP C103: High-Visibility Fence shall be installed to control traffic.  l Upon project completion and site stabilization, all construction accesses intended as per- manent access for maintenance shall be permanently stabilized. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 319 Maintenance Standards Inspect stabilized areas regularly, especially after large storm events. Crushed rock, gravel base, etc., shall be added as required to maintain a stable driving surface  and to stabilize any areas that have eroded. Following construction, these areas shall be restored to pre-construction condition or better to pre- vent future erosion. Perform street cleaning at the end of each day or more often if necessary. BMP C120: Temporary and Permanent Seeding Purpose Seeding reduces erosion by stabilizing exposed soils. A well-established vegetative cover is one  of the most effective methods of reducing erosion. Conditions of Use  l Use seeding throughout the project on disturbed areas that have reached final grade or that  will remain unworked for more than 30 days. See II-2.5 Element 5: Stabilize Soils for spe- cific timelines for stabilizing exposed soils.  l See Table II-4.4: Seeding Windows in Western Washington (continued) for appropriate  seeding windows.  l Review all disturbed areas in late August to early September and complete all seeding by  the end of September. Otherwise, vegetation will not establish itself enough to provide  more than average protection.  l Mulch is required at all times for seeding because it protects seeds from heat, moisture  loss, and transport due to runoff. Mulch can be applied on top of the seed or simultaneously  by hydroseeding. See BMP C121: Mulching for specifications.  l Seed and mulch all disturbed areas not otherwise vegetated at final site stabilization. Final  stabilization means the completion of all soil disturbing activities at the site and the estab- lishment of a permanent vegetative cover, or equivalent permanent stabilization measures  (such as pavement, riprap, gabions, or geotextiles) which will prevent erosion. See BMP  T5.13: Post-Construction Soil Quality and Depth. Month Seeding Recommendations January Seeding requires a cover of mulch or an erosion control blanket until 75% grass  cover is establishedFebruary March Table II-4.4: Seeding Windows in Western Washington 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 325 Month Seeding Recommendations April Optimum seeding windowMay June July Seeding requires irrigation until 75% grass cover is established August September Optimum seeding window October Seeding requires a cover of mulch or an erosion control blanket until 75 percent  grass cover is establishedNovember December Table II-4.4: Seeding Windows in Western Washington (continued) Design and Installation Specifications General  l Install channels intended for vegetation before starting major earthwork and hydroseed with  a Bonded Fiber Matrix (BFM). For vegetated channels that will have high flows, install  erosion control blankets over the top of hydroseed. Before allowing water to flow in veget- ated channels, establish a 75% vegetation cover. If vegetated channels cannot be estab- lished by seed before water flow, install sod or prevegetated mats in the channel bottom  over top of hydromulch and erosion control blankets.  l Confirm the installation of all required stormwater control measures to prevent seed from  washing away.  l Hydroseed applications shall include a minimum of 1,500 pounds per acre (lb/acre) of  mulch with 3% tackifier. See BMP C121: Mulching for specifications.  l Areas that will have seeding only, and not landscaping, may need compost or meal-based  mulch included in the hydroseed in order to establish vegetation. Re-install native topsoil on  the disturbed soil surface before application. See BMP T5.13: Post-Construction Soil Qual- ity and Depth.  l When installing seed via hydroseeding operations, only about 1/3 of the seed actually ends  up in contact with the soil surface. This reduces the ability to establish a good stand of grass  quickly. To overcome this, consider increasing seed quantities by up to 50 percent.  l Vegetation establishment can be enhanced by one of the following two approaches:  o Approach 1: Enhance vegetation establishment by dividing the hydromulch operation  into two phases: 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 326  n Phase 1 – Install all seed and fertilizer with 25% to 30% mulch and tackifier  onto the soil in the first lift.  n Phase 2 – Install the remaining mulch and tackifier over the first lift.  o Approach 2: Vegetation can also be enhanced by:  n Installing the mulch, seed, fertilizer, and tackifier in one lift;   n Spreading or blowing straw over the top of the hydromulch at a rate of about  800 to 1,000 lb/acre; or  n Holding straw in place with a standard tackifier. Both of these approaches (Approach 1 and Approach 2) will increase cost moderately but  will greatly improve and enhance vegetative establishment. The increased cost may be off- set by the reduced need for:  o Irrigation,  o Reapplication of mulch, and   o Repair of failed slope surfaces. Either of these approaches can use standard hydromulch (1,500 lb/acre minimum) and  BFM/mechanically bonded fiber matrix (MBFM) (3,000 lb/acre minimum).  l Seed may be installed by hand if it is:  o Temporary and covered by straw, mulch, or topsoil; or  o Permanent in small areas (usually less than 1 acre) and covered with mulch, topsoil,  or erosion blankets.  l Consult the local suppliers and/or the local conservation district for their recommendations  for appropriate seed mixes and application rates. The appropriate mix depends on a variety  of factors, including location, exposure, soil type, slope, and expected foot traffic.   l In addition to meeting erosion control functions and not hindering maintenance operations,  selection of long-lived, successional growth native vegetation that can compete against or  exclude weeds and grow with minimal maintenance after plant establishment is preferred.  Provide diversity to the greatest extent possible and plan for a succession of flowering  times to improve pollinator habitat.  l The seed mixes listed in Table II-4.5: Temporary and Permanent Seed Mixes for Western  Washington (continued) include recommended mixes for both temporary and permanent  seeding. Alternative seed mixes approved by the local jurisdiction may also be used.  l Apply the mixes in Table II-4.5: Temporary and Permanent Seed Mixes for Western Wash- ington (continued), with the exception of the wet area seed mix, at a rate of 120 pounds per  acre. This rate can be reduced if soil amendments or slow-release fertilizers are used.  Apply the wet area seed mix at a rate of 60 pounds per acre. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 327 Common Name Latin Name % Weight % Purity % Germination Temporary Erosion Control Seed Mix A standard mix for areas requiring a temporary vegetative cover. Chewings or  annual  blue grass Festuca rubra var. commutata or  Poa anna 40 98 90 Perennial rye  Lolium perenne 50 98 90 Redtop or colonial  bentgrass  Agrostis alba or  Agrostis tenuis 5 92 85 White dutch clover Trifolium repens 5 98 90 Landscaping Seed Mix A recommended mix for landscaping seed. Perennial rye blend Lolium perenne 70 98 90 Chewings and red  fescue blend Festuca rubra var. commutata or Fes- tuca rubra 30 98 90 Low-Growing Turf Seed Mix A turf seed mix for dry situations where there is no need for watering. This mix requires very little main- tenance. Dwarf tall fescue  (several  varieties) Festuca arundin- acea var. 45 98 90 Dwarf perennial rye  (Barclay) Lolium perenne var. barclay 30 98 90 Red fescue Festuca rubra 20 98 90 Colonial bentgrass Agrostis tenuis 5 98 90 Bioswale Seed Mix A seed mix for bioswales and other intermittently wet areas. Tall or meadow fes- cue Festuca arundin- acea or   Festuca elatior 75-80 98 90 Seaside/Creeping  bentgrass Agrostis palustris 10-15 92 85 Redtop bentgrass Agrostis alba or  Agrostis gigantea 5-10 90 80 Wet Area Seed Mix Table II-4.5: Temporary and Permanent Seed Mixes for Western Washington 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 328 Common Name Latin Name % Weight % Purity % Germination A low-growing, relatively non-invasive seed mix appropriate for very wet areas that are not regulated wet- lands. Consult Hydraulic Permit Authority (HPA) for seed mixes if applicable. Tall or meadow fes- cue Festuca arundin- acea or Festuca elatior 60-70 98 90 Seaside/Creeping  bentgrass Agrostis palustris 10-15 98 85 Meadow foxtail Alepocurus pratensis 10-15 90 80 Alsike clover Trifolium hybridum 1-6 98 90 Redtop bentgrass Agrostis alba 1-6 92 85 Meadow Seed Mix A recommended meadow seed mix for infrequently maintained areas or non-maintained areas where  colonization by native plants is desirable. Likely applications include rural road and utility right-of-way.  Seeding should take place in September or very early October in order to obtain adequate establishment  prior to the winter months. Consider the appropriateness of clover, a fairly invasive species, in the mix.  Amending the soil can reduce the need for clover. Redtop or Oregon  bentgrass Agrostis alba or  Agrostis ore- gonensis 20 92 85 Red fescue Festuca rubra 70 98 90 White dutch clover Trifolium repens 10 98 90 Table II-4.5: Temporary and Permanent Seed Mixes for Western Washington (continued) Roughening and Rototilling  l The seedbed should be firm and rough. Roughen all soil no matter what the slope. Track  walk slopes before seeding if engineering purposes require compaction. Backblading or  smoothing of slopes greater than 4H:1V is not allowed if they are to be seeded.  l Restoration-based landscape practices require deeper incorporation than that provided by  a simple, single-pass rototilling treatment. Wherever practical, initially rip the subgrade to  improve long-term permeability, infiltration, and water inflow qualities. At a minimum, per- manent areas shall receive soil amendments to achieve organic matter and permeability  performance defined in engineered soil/landscape systems. For systems that are deeper  than 8 inches, complete the rototilling process in multiple lifts, or prepare the soil amend- ments per the specifications and place to achieve the specified depth. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 329 Fertilizers  l Conducting soil tests to determine the exact type and quantity of fertilizer needed is recom- mended. This will prevent the overapplication of fertilizer.  l Organic matter is the most appropriate form of fertilizer because it provides nutrients (includ- ing nitrogen, phosphorus, and potassium) in the least water-soluble form.  l In general, use 10-4-6 N-P-K (nitrogen-phosphorus-potassium) fertilizer at a rate of 90  pounds per acre.   l Always use slow-release fertilizers because they are more efficient and have fewer envir- onmental impacts. Do not add fertilizer to the hydromulch machine, or agitate, more than 20  minutes before use. Too much agitation destroys the slow-release coating.  l There are numerous products available to take the place of chemical fertilizers, including  several with seaweed extracts that are beneficial to soil microbes and organisms. If 100%  cottonseed meal is used as the mulch in hydroseed, chemical fertilizer may not be neces- sary. Cottonseed meal provides a good source of long-term, slow-release, available nitro- gen.  Bonded Fiber Matrix and Mechanically Bonded Fiber Matrix  l On steep slopes, use Bonded Fiber Matrix (BFM) or Mechanically Bonded Fiber Matrix  (MBFM) products. Apply BFM/MBFM products at a minimum rate of 3,000 pounds per acre  with approximately 10% tackifier. Achieve a minimum of 95% soil coverage during applic- ation. Numerous products are available commercially. Most products require 24-36 hours to  cure before rainfall, and cannot be installed on wet or saturated soils. Generally, products  come in 40-50 pound bags and include all necessary ingredients except for seed and fer- tilizer.  l Install products per manufacturer's instructions.  l BFMs and MBFMs provide good alternatives to blankets in most areas requiring vegetation  establishment. Advantages over blankets include the following:  o BFM and MBFMs do not require surface preparation.  o Helicopters can assist in installing BFM and MBFMs in remote areas.  o On slopes steeper than 2.5H:1V, blanket installers may require ropes and harnesses  for safety.  o Installing BFM and MBFMs can save at least $1,000 per acre compared to blankets. Maintenance Standards  l Reseed any seeded areas that fail to establish at least 75% cover (100% cover for areas  that receive sheet or concentrated flows) of all seeded areas after 3 months of active  growth following germination during the growing season. If reseeding is ineffective, use an  alternate method, such as sodding, mulching, or nets/blankets. If winter weather prevents  2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 330 adequate grass growth, this time limit may be relaxed at the discretion of the local authority  when sensitive areas would otherwise be protected.  l Reseed and protect by mulch any areas that experience erosion after achieving adequate  cover. If the erosion problem is drainage related, the problem shall be fixed and the eroded  area reseeded and protected by mulch.  l Supply seeded areas with adequate moisture, but do not water to the extent that it causes  runoff. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did  not pass through the Technology Assessment Protocol – Ecology (TAPE) process. Local jur- isdictions may choose not to accept these products, or may require additional testing prior to con- sideration for local use. Products that Ecology has approved as functionally equivalent are  available for review on Ecology’s website at:  https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies BMP C121: Mulching Purpose Mulching soils provides immediate temporary protection from erosion. Mulch also enhances plant  establishment by conserving moisture, holding fertilizer, seed, and topsoil in place, and mod- erating soil temperatures. There are a variety of mulches that can be used. This section discusses  only the most common types of mulch. Conditions of Use As a temporary cover measure, mulch should be used:  l For less than 30 days on disturbed areas that require cover.  l At all times for seeded areas, especially during the wet season and during the hot summer  months.  l During the wet season on slopes steeper than 3H:1V with more than 10 feet of vertical  relief. Mulch may be applied at any time of the year and must be refreshed periodically. For seeded areas, mulch may be made up of 100 percent:   l Cottonseed meal;   l Fibers made of wood, recycled cellulose, hemp, or kenaf;  2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 331  l Compost;   l Or blends of these. Tackifier shall be plant-based, such as guar or alpha plantago, or chemical-based such as poly- acrylamide or polymers.  Generally, mulches come in 40-50 pound bags. Seed and fertilizer are added at time of applic- ation. Recycled cellulose may contain polychlorinated biphenyl (PCBs). Ecology recommends that  products should be evaluated for PCBs prior to use. Refer to BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection for conditions of use. PAM  shall not be directly applied to water or allowed to enter a water body. Any mulch or tackifier product used shall be installed per the manufacturer’s instructions. Design and Installation Specifications For mulch materials, application rates, and specifications, see Table II-4.7: Mulch Standards and  Guidelines (continued). Consult with the local supplier or the local conservation district for their  recommendations. Increase the application rate until the ground is 95% covered (i.e. not visible  under the mulch layer). Note: Thickness may be increased for disturbed areas in or near sensitive  areas or other areas highly susceptible to erosion. Where the option of “Compost” is selected, it should be a coarse compost that meets the size grad- ations listed in Table II-4.6: Size Gradations of Compost as Mulch Material when tested in accord- ance with Test Method 02.02-B found in Test Methods for the Examination of Composting and Compost (Thompson, 2001). Mulch used within the ordinary high-water mark of surface waters should be selected to minimize  potential flotation of organic matter. Composted organic materials have higher specific gravities  (densities) than straw, wood, or chipped material. Consult the Hydraulic Permit Authority (HPA)  for mulch mixes if applicable. Sieve Size Percent Passing 3"100% 1"90% - 100% 3/4"70% - 100% 1/4"40% - 100% Table II-4.6: Size Gradations of Compost as Mulch Material Mulch Mater- ial Guideline Description Straw Quality Stand-Air-dried; free from undesirable seed and coarse material. Table II-4.7: Mulch Standards and Guidelines 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 332 Mulch Mater- ial Guideline Description ards Application Rates 2" to 3" thick; 5 bales per 1,000 sf or 2 to 3 tons per acre Remarks Cost-effective protection when applied with adequate thickness.  Hand-application generally requires greater thickness than blown  straw. The thickness of straw may be reduced by half when used in  conjunction with seeding. In windy areas, straw must be held in  place by crimping, using a tackifier, or covering with netting. Blown  straw always has to be held in place with a tackifier because even  light winds will blow it away. Straw, however, has several defi- ciencies that should be considered when selecting mulch materials.  It often introduces and/or encourages the propagation of weed spe- cies, and it has no significant long-term benefits. Straw should only  be used if mulches with long-term benefits are unavailable locally. It  should also not be used within the ordinary high-water elevation of  surface waters (due to flotation). Hydromulch Quality Stand- ards No growth inhibiting factors. Application Rates Approx. 35-45 lbs per 1,000 sf or 1,500 - 2,000 lbs per acre Remarks Shall be applied with hydromulcher. Shall not be used without seed  and tackifier unless the application rate is at least doubled. Fibers  longer than about 3/4 - 1 inch clog hydromulch equipment. Fibers  should be kept to less than 3/4 inch. Compost Quality Stand- ards No visible water or dust during handling. Must be produced per WAC  173-350, Solid Waste Handling Standards, but may have up to 35%  biosolids. Application Rates 2" thick minimum; approximately 100 tons per acre (approximately  750 lbs per cubic yard) Remarks More effective control can be obtained by increasing thickness to 3".  Compost makes an excellent mulch for protecting final grades until  landscaping because it can be directly seeded or tilled into soil as an  amendment. Compost used for mulch has a coarser size gradation  than compost used for BMP C125: Topsoiling / Composting or BMP  T5.13: Post-Construction Soil Quality and Depth. It is more stable  and practical to use in wet areas and during rainy weather con- ditions. Do not use compost near wetlands if biosolids are included.  Do not use compost near phosphorous impaired water bodies. Chipped Site Vegetation Quality Stand- ards Gradations from fines to 6 inches in length for texture, variation, and  interlocking properties. Include a mix of various sizes so that the  Table II-4.7: Mulch Standards and Guidelines (continued) 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 333 Mulch Mater- ial Guideline Description average size is between 2 and 4 inches. Application Rates 2" thick minimum. Remarks This is a cost-effective way to dispose of debris from clearing and  grubbing, and it eliminates the problems associated with burning.  Generally, it should not be used on slopes above approximately 10%  because of its tendency to be transported by runoff. It is not recom- mended within 200 feet of surface waters. If permanent seeding or  planting is expected shortly after mulch, the decomposition of the  chipped vegetation may tie up nutrients important to grass estab- lishment.  Note: Thick application of this material over existing grass, herb- aceous species, and some groundcovers could smother and kill  vegetation. Wood-Based Mulch Quality Stand- ards No visible water or dust during handling. Must be purchased from a  supplier with a Solid Waste Handling Permit or one exempt from  solid waste regulations. Application Rates 2" thick minimum; approximately 100 tons per acre (approximately  750 lbs. per cubic yard). Remarks This material is often called "wood straw" or "hog fuel". The use of  mulch ultimately improves the organic matter in the soil. Special cau- tion is advised regarding the source and composition of wood-based  mulches. Its preparation typically does not provide any weed seed  control, so evidence of residual vegetation in its composition or  known inclusion of weed plants or seeds should be monitored and  prevented (or minimized). Wood Strand Mulch Quality Stand- ards A blend of loose, long, thin wood pieces derived from native conifer  or deciduous trees with high length-to-width ratio. Application Rates 2" thick minimum. Remarks Cost-effective protection when applied with adequate thickness. A  minimum of 95% of the wood strand shall have lengths between 2  and 10 inches, with a width and thickness between 1/16 and 0.5  inches. The mulch shall not contain resin, tannin, or other com- pounds in quantities that would be detrimental to plant life. Sawdust  or wood shavings shall not be used as mulch. See specification 9- 14.4(4) from the Standard Specifications for Road, Bridge, and Muni- cipal Construction (WSDOT, 2016) Table II-4.7: Mulch Standards and Guidelines (continued) Maintenance Standards The thickness of the mulch cover must be maintained. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 334 Any areas that experience erosion shall be remulched and/or protected with a net or blanket. If the  erosion problem is drainage related, then the problem shall be fixed and the eroded area rem- ulched. BMP C122: Nets and Blankets Purpose Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in  place on steep slopes and in channels so that vegetation can become well established. In addi- tion, some nets and blankets can be used to permanently reinforce turf to protect drainage sys- tems during high flows.  Nets (commonly called matting) are strands of material woven into an open, but high-tensile  strength net (e.g. coconut fiber matting). Blankets are strands of material that are not tightly  woven, but instead form a layer of interlocking fibers, typically held together by a biodegradable or  photodegradable netting (for example, excelsior or straw blankets). They generally have lower  tensile strength than nets, but cover the ground more completely. Coir (coconut fiber) fabric  comes as both nets and blankets. Conditions of Use Erosion control netting and blankets shall be made of natural plant fibers unaltered by synthetic  materials. Erosion control nets and blankets should be used:  l To aid permanent vegetated stabilization of slopes 2H:1V or greater and with more than 10  feet of vertical relief.  l For drainage ditches and swales (highly recommended). The application of appropriate net- ting or blanket to drainage ditches and swales can protect bare soil from channelized runoff  while vegetation is established. Nets and blankets also can capture a great deal of sed- iment due to their open, porous structure. Nets and blankets can be used to permanently  stabilize channels and may provide a cost-effective, environmentally preferable alternative  to riprap. Disadvantages of nets and blankets include:  l Surface preparation is required.  l On slopes steeper than 2.5H:1V, net and blanket installers may need to be roped and har- nessed for safety.  l They cost at least $4,000 - $6,000 per acre installed. Advantages of nets and blankets include:  l Installation without mobilizing special equipment.  l Installation by anyone with minimal training 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 335 BMP C123: Plastic Covering Purpose Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas. Conditions of Use Plastic covering may be used on disturbed areas that require cover measures for less than 30  days, except as stated below.  l Plastic is particularly useful for protecting cut and fill slopes and stockpiles. However, the rel- atively rapid breakdown of most polyethylene sheeting makes it unsuitable for applications  greater than six months.  l Due to rapid runoff caused by plastic covering, do not use this method upslope of areas that  might be adversely impacted by concentrated runoff. Such areas include steep and/or  unstable slopes.  l Plastic sheeting may result in increased runoff volumes and velocities, requiring additional  on-site measures to counteract the increases. Creating a trough with wattles or other mater- ial can convey clean water away from these areas.  l To prevent undercutting, trench and backfill rolled plastic covering products.  l Although the plastic material is inexpensive to purchase, the cost of installation, main- tenance, removal, and disposal add to the total costs of this BMP.  l Whenever plastic is used to protect slopes, install water collection measures at the base of  the slope. These measures include plastic-covered berms, channels, and pipes used to con- vey clean rainwater away from bare soil and disturbed areas. Do not mix clean runoff from a  plastic covered slope with dirty runoff from a project.  l Other uses for plastic include:  o Temporary ditch liner.  o Pond liner in temporary sediment pond.  o Liner for bermed temporary fuel storage area if plastic is not reactive to the type of  fuel being stored.  o Emergency slope protection during heavy rains.  o Temporary drainpipe (“elephant trunk”) used to direct water. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 340 Design and Installation Specifications  l Plastic slope cover must be installed as follows:  1. Run plastic up and down the slope, not across the slope.  2. Plastic may be installed perpendicular to a slope if the slope length is less than 10  feet.  3. Provide a minimum of 8-inch overlap at the seams.  4. On long or wide slopes, or slopes subject to wind, tape all seams.  5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench at the top of the  slope and backfill with soil to keep water from flowing underneath.  6. Place sand filled burlap or geotextile bags every 3 to 6 feet along seams and tie them  together with twine to hold them in place.  7. Inspect plastic for rips, tears, and open seams regularly and repair immediately. This  prevents high velocity runoff from contacting bare soil, which causes extreme  erosion.  8. Sandbags may be lowered into place tied to ropes. However, all sandbags must be  staked in place.  l Plastic sheeting shall have a minimum thickness of 6 mil.  l If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable protection  shall be installed at the toe of the slope in order to reduce the velocity of runoff. Maintenance Standards  l Torn sheets must be replaced and open seams repaired.  l Completely remove and replace the plastic if it begins to deteriorate due to ultraviolet radi- ation.  l Completely remove plastic when no longer needed.  l Dispose of old tires used to weight down plastic sheeting appropriately. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did  not pass through the Technology Assessment Protocol – Ecology (TAPE) process. Local jur- isdictions may choose not to accept these products, or may require additional testing prior to con- sideration for local use. Products that Ecology has approved as functionally equivalent are  available for review on Ecology’s website at:  https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 341 BMP C124: Sodding Purpose The purpose of sodding is to establish turf for immediate erosion protection and to stabilize drain- age paths where concentrated overland flow will occur. Conditions of Use Sodding may be used in the following areas:  l Disturbed areas that require short-term or long-term cover.  l Disturbed areas that require immediate vegetative cover.  l All waterways that require vegetative lining. Waterways may also be seeded rather than  sodded, and protected with a net or blanket. Design and Installation Specifications Sod shall be free of weeds, have a uniform thickness (approximately 1-inch thick), and have a  dense root mat for mechanical strength. The following steps are recommended for sod installation:  1. Shape and smooth the surface to final grade in accordance with the approved grading plan.  Consider any areas (such as swales) that  need to be overexcavated below design elevation  to allow room for placing soil amendment and sod.  2. Amend 4 inches (minimum) of compost into the top 8 inches of the soil if the organic content  of the soil is less than ten percent or the permeability is less than 0.6 inches per hour. See  Ecology's Compost web page for further information: https://ecology.wa.gov/Waste-Toxics/Reducing-recycling-waste/Organic-mater- ials/Managing-organics-compost  3. Fertilize according to the sod supplier's recommendations.  4. Work lime and fertilizer 1 to 2 inches into the soil, and smooth the surface.  5. Lay strips of sod beginning at the lowest area to be sodded and perpendicular to the dir- ection of water flow. Wedge strips securely into place. Square the ends of each strip to  provide for a close, tight fit. Stagger joints at least 12 inches. Staple on slopes steeper than  3H:1V. Staple the upstream edge of each sod strip.  6. Roll the sodded area and irrigate.  7. When sodding is carried out in alternating strips or other patterns, seed the areas between  the sod immediately after sodding. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 342 Maintenance Standards If the grass is unhealthy, the cause shall be determined and appropriate action taken to rees- tablish a healthy ground cover. If it is impossible to establish a healthy ground cover due to fre- quent saturation, instability, or some other cause, the sod shall be removed, the area seeded with  an appropriate mix, and protected with a net or blanket (BMP C122: Nets and Blankets). BMP C125: Topsoiling / Composting Purpose Topsoiling and composting provide a suitable growth medium for final site stabilization with veget- ation. While not a permanent cover practice in itself, topsoiling and composting are an integral  component of providing permanent cover in those areas where there is an unsuitable soil surface  for plant growth. Use this BMP in conjunction with other BMPs such as BMP C120: Temporary  and Permanent Seeding, BMP C121: Mulching, or BMP C124: Sodding.  Implementation of this BMP may meet the post-construction requirements of BMP T5.13: Post- Construction Soil Quality and Depth. Native soils and disturbed soils that have been organically amended not only retain much more  stormwater, but also serve as effective biofilters for urban pollutants and, by supporting more vig- orous plant growth, reduce the water, fertilizer, and/or pesticides needed to support installed land- scapes. Topsoil does not include any subsoils but only the material from the top several inches  including organic debris. Conditions of Use  l Permanent landscaped areas shall contain healthy topsoil that reduces the need for fer- tilizers, improves overall topsoil quality, provides for better vegetative health and vitality,  improves hydrologic characteristics, and reduces the need for irrigation.  l Leave native soils and the duff layer undisturbed to the maximum extent practicable. Strip- ping of existing, properly functioning soil system and vegetation for the purpose of top- soiling during construction is not acceptable. Preserve existing soil systems in undisturbed  and uncompacted conditions if functioning properly.  l Areas that already have good topsoil, such as undisturbed areas, do not require soil amend- ments.  l Restore, to the maximum extent practical, native soils disturbed during clearing and grading  to a condition equal to or better than the original site condition’s moisture-holding capacity.  Use on-site native topsoil, incorporate amendments into on-site soil, or import blended top- soil to meet this requirement.  l Topsoiling is a required procedure when establishing vegetation on shallow soils, and soils  of critically low pH (high acid) levels. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 343 BMP C140: Dust Control Purpose Dust control prevents wind transport of dust from disturbed soil surfaces onto roadways, into drain- age systems, and into surface waters. Conditions of Use Use dust control in areas (including roadways) subject to surface and air movement of dust where  on-site or off-site impacts to roadways, drainage systems, or surface waters are likely. Design and Installation Specifications  l Vegetate or mulch areas that will not receive vehicle traffic. In areas where planting, mulch- ing, or paving is impractical, apply gravel or landscaping rock.  l Limit dust generation by clearing only those areas where immediate activity will take place,  leaving the remaining area(s) in the original condition. Maintain the original ground cover as  long as practical.  l Construct natural or artificial windbreaks or windscreens. These may be designed as  enclosures for small dust sources.  l Sprinkle the site with water until the surface is wet. Repeat as needed. To prevent carryout  of mud onto the street, refer to BMP C105: Stabilized Construction Access and BMP C106:  Wheel Wash.  l Irrigation water can be used for dust control. Irrigation systems should be installed as a first  step on sites where dust control is a concern.  l Spray exposed soil areas with a dust palliative, following the manufacturer’s instructions  and cautions regarding handling and application. Used oil is prohibited from use as a dust  suppressant. Local jurisdictions may approve other dust palliatives such as calcium chlor- ide or PAM.  l PAM (BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection) added to water at a  rate of 0.5 pounds per 1,000 gallons of water per acre and applied from a water truck is  more effective than water alone. This is due to the increased infiltration of water into the soil  and reduced evaporation. In addition, small soil particles are bonded together and are not  as easily transported by wind. Adding PAM may reduce the quantity of water needed for  dust control.  Note that the application rate specified here applies to this BMP, and is not the same applic- ation rate that is specified in BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection,  but the downstream protections still apply. Refer to BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection for conditions of use.  PAM shall not be directly applied to water or allowed to enter a water body. PAM use shall  2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 356 be reviewed and approved by the local permitting authority and discharge of PAM may be a  basis for penalties per RCW 90.48.080.  l Contact your local Air Pollution Control Authority for guidance and training on other dust  control measures. Compliance with the local Air Pollution Control Authority constitutes com- pliance with this BMP. See the following website for more information: https://ecology.wa.gov/About-us/Our-role-in-the-community/Partnerships-com- mittees/Clean-air-agencies  l Use vacuum street sweepers.  l Remove mud and other dirt promptly so it does not dry and then turn into dust.  l Techniques that can be used for unpaved roads and lots include:  o Lower speed limits. High vehicle speed increases the amount of dust stirred up from  unpaved roads and lots.  o Upgrade the road surface strength by improving particle size, shape, and mineral  types that make up the surface and base materials.  o Add surface gravel to reduce the source of dust emission. Limit the amount of fine  particles (those smaller than .075 mm) to 10 to 20 percent.  o Use geotextile fabrics to increase the strength of new roads or roads undergoing  reconstruction.  o Encourage the use of alternate, paved routes, if available.  o Apply chemical dust suppressants using the admix method, blending the product with  the top few inches of surface material. Suppressants may also be applied as surface  treatments.  o Limit dust-generating work on windy days.  o Pave unpaved permanent roads and other trafficked areas. Maintenance Standards Respray area as necessary to keep dust to a minimum. BMP C150: Materials on Hand Purpose Keep quantities of erosion prevention and sediment control materials on the project site at all  times to be used for regular maintenance and emergency situations such as unexpected heavy  rains. Having these materials on-site reduces the time needed to replace existing or implement  new BMPs when inspections indicate that existing BMPs are not meeting the Construction  SWPPP requirements. In addition, contractors can save money by buying some materials in bulk  and storing them at their office or yard. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 357  l At no time shall concrete be washed off into the footprint of an area where an infiltration fea- ture will be installed.  l Wash equipment difficult to move, such as concrete paving machines, in areas that do not  directly drain to natural or constructed stormwater conveyance or potential infiltration areas.  l Do not allow washwater from areas, such as concrete aggregate driveways, to drain directly  (without detention or treatment) to natural or constructed stormwater conveyances.  l Contain washwater and leftover product in a lined container when no  designated concrete  washout areas (or formed areas, allowed as described above) are available. Dispose of con- tained concrete and concrete washwater (process water) properly.  l Always use forms or solid barriers for concrete pours, such as pilings, within 15-feet of sur- face waters.  l Refer to BMP C252: Treating and Disposing of High pH Water for pH adjustment require- ments.  l Refer to the Construction Stormwater General Permit (CSWGP) for pH monitoring require- ments if the project involves one of the following activities:  o Significant concrete work (as defined in the CSWGP).  o The use of soils amended with (but not limited to) Portland cement-treated base,  cement kiln dust or fly ash.  o Discharging stormwater to segments of water bodies on the 303(d) list (Category 5)  for high pH. Maintenance Standards Check containers for holes in the liner daily during concrete pours and repair the same day. BMP C152: Sawcutting and Surfacing Pollution Prevention Purpose Sawcutting and surfacing operations generate slurry and process water that contain fine particles  and have a high pH (concrete cutting), both of which can violate the water quality standards in the  receiving water. Concrete spillage or concrete discharge to waters of the State is prohibited. Use  this BMP to minimize and eliminate process water and slurry created by sawcutting or surfacing  from entering waters of the State. Conditions of Use Utilize these management practices anytime sawcutting or surfacing operations take place. Saw- cutting and surfacing operations include, but are not limited to: 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 360  l Sawing  l Coring  l Grinding  l Roughening  l Hydro-demolition  l Bridge and road surfacing Design and Installation Specifications  l Vacuum slurry and cuttings during cutting and surfacing operations.  l Slurry and cuttings shall not remain on permanent concrete or asphalt pavement overnight.  l Slurry and cuttings shall not drain to any natural or constructed drainage conveyance includ- ing stormwater systems. This may require temporarily blocking catch basins.  l Dispose of collected slurry and cuttings in a manner that does not violate groundwater or  surface water quality standards.  l Do not allow process water generated during hydro-demolition, surface roughening, or sim- ilar operations to drain to any natural or constructed drainage conveyance including storm- water systems. Dispose of process water in a manner that does not violate groundwater or  surface water quality standards.  l Handle and dispose of cleaning waste material and demolition debris in a manner that does  not cause contamination of water. Dispose of sweeping material from a pick-up sweeper at  an appropriate disposal site. Maintenance Standards Continually monitor operations to determine whether slurry, cuttings, or process water could enter  waters of the state. If inspections show that a violation of water quality standards could occur, stop  operations and immediately implement preventive measures such as berms, barriers, secondary  containment, and/or vacuum trucks. BMP C153: Material Delivery, Storage, and Containment Purpose Prevent, reduce, or eliminate the discharge of pollutants to the stormwater system or water- courses from material delivery and storage. Minimize the storage of hazardous materials on-site,  store materials in a designated area, and install secondary containment. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 361 Conditions of Use Use at construction sites with delivery and storage of the following materials:  l Petroleum products such as fuel, oil and grease  l Soil stabilizers and binders (e.g., polyacrylamide)  l Fertilizers, pesticides, and herbicides  l Detergents  l Asphalt and concrete compounds  l Hazardous chemicals such as acids, lime, adhesives, paints, solvents, and curing com- pounds  l Any other material that may be detrimental if released to the environment Design and Installation Specifications  l The temporary storage area should be located away from vehicular traffic, near the con- struction entrance(s), and away from waterways or storm drains.  l Safety Data Sheets (SDS) should be supplied for all materials stored. Chemicals should be  kept in their original labeled containers.  l Hazardous material storage on-site should be minimized.  l Hazardous materials should be handled as infrequently as possible.  l During the wet weather season (October 1 – April 30), consider storing materials in a  covered area.  l Materials should be stored in secondary containments, such as an earthen dike, horse  trough, or even a children’s wading pool for non-reactive materials such as detergents, oil,  grease, and paints. Small amounts of material may be secondarily contained in “bus boy”  trays or concrete mixing trays.  l Do not store chemicals, drums, or bagged materials directly on the ground. Place these  items on a pallet and, when possible, within secondary containment.  l If drums must be kept uncovered, store them at a slight angle to reduce ponding of rain- water on the lids to reduce corrosion. Domed plastic covers are inexpensive and snap to  the top of drums, preventing water from collecting.  l Liquids, petroleum products, and substances listed in 40 CFR Parts 110, 117, or 302 shall  be stored in approved containers and drums and shall not be overfilled. Containers and  drums shall be stored in temporary secondary containment facilities.  l Temporary secondary containment facilities shall provide for a spill containment volume  able to contain 10% of the total enclosed container volume of all containers, or 110% of the  capacity of the largest container within its boundary, whichever is greater. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 362  l Secondary containment facilities shall be impervious to the materials stored therein for a  minimum contact time of 72 hours.  l Sufficient separation should be provided between stored containers to allow for spill  cleanup and emergency response access.  l During the wet weather season (Oct 1 – April 30), each secondary containment facility shall  be covered during non-working days.  l Secondary containment facilities shall be covered at all times, except when in active use.  l Keep material storage areas clean, organized, and equipped with an ample supply of appro- priate spill clean-up material (spill kit).  l The spill kit should include, at a minimum:  o 1 - Water resistant nylon bag  o 3 - Oil absorbent socks 3”x 4’  o 2 - Oil absorbent socks 3”x 10’  o 12 - Oil absorbent pads 17”x19”  o 1 - Pair splash resistant goggles  o 3 - Pairs nitrile gloves  o 10 - Disposable bags with ties  o Instructions Maintenance Standards  l Secondary containment facilities shall be maintained free of accumulated rainwater and  spills. In the event of spills or leaks, accumulated rainwater and spills shall be collected and  placed into drums. These liquids shall be handled as hazardous waste unless testing  determines them to be non-hazardous.  l Re-stock spill kit materials as needed. BMP C154: Concrete Washout Area Purpose Prevent or reduce the discharge of pollutants from concrete waste to stormwater by conducting  washout off-site, or performing on-site washout in a designated area. Conditions of Use Concrete washout areas are implemented on construction projects where: 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 363  l Concrete is used as a construction material  l It is not possible to dispose of all concrete wastewater and washout off-site (ready mix  plant, etc.).  l Concrete truck drums are washed on-site. Note that auxiliary concrete truck components (e.g. chutes and hoses) and small concrete  handling equipment (e.g. hand tools, screeds, shovels, rakes, floats, trowels, and wheel- barrows) may be washed into formed areas awaiting concrete pour. At no time shall concrete be washed off into the footprint of an area where an infiltration feature  will be installed. Design and Installation Specifications Implementation  l Perform washout of concrete truck drums at an approved off-site location or in designated  concrete washout areas only.  l Do not wash out concrete onto non-formed areas, or into storm drains, open ditches,  streets, or streams.  l Wash equipment difficult to move, such as concrete paving machines, in areas that do not  directly drain to natural or constructed stormwater conveyance or potential infiltration areas.  l Do not allow excess concrete to be dumped on-site, except in designated concrete washout  areas as allowed above.  l Concrete washout areas may be prefabricated concrete washout containers, or self- installed structures (above-grade or below-grade).  l Prefabricated containers are most resistant to damage and protect against spills and leaks.  Companies may offer delivery service and provide regular maintenance and disposal of  solid and liquid waste.  l If self-installed concrete washout areas are used, below-grade structures are preferred  over above-grade structures because they are less prone to spills and leaks.  l Self-installed above-grade structures should only be used if excavation is not practical.  l Concrete washout areas shall be constructed and maintained in sufficient quantity and size  to contain all liquid and concrete waste generated by washout operations. Education  l Discuss the concrete management techniques described in this BMP with the ready-mix  concrete supplier before any deliveries are made.  l Educate employees and subcontractors on the concrete waste management techniques  described in this BMP. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 364  l Arrange for the contractor’s superintendent or Certified Erosion and Sediment Control Lead  (CESCL) to oversee and enforce concrete waste management procedures.  l A sign should be installed adjacent to each concrete washout area to inform concrete equip- ment operators to utilize the proper facilities. Contracts Incorporate requirements for concrete waste management into concrete supplier and sub- contractor agreements. Location and Placement  l Locate concrete washout areas at least 50 feet from sensitive areas such as storm drains,  open ditches, water bodies, or wetlands.  l Allow convenient access to the concrete washout area for concrete trucks, preferably near  the area where the concrete is being poured.  l If trucks need to leave a paved area to access the concrete washout area, prevent track-out  with a pad of rock or quarry spalls (see BMP C105: Stabilized Construction Access). These  areas should be far enough away from other construction traffic to reduce the likelihood of  accidental damage and spills.  l The number of concrete washout areas you install should depend on the expected demand  for storage capacity.  l On large sites with extensive concrete work, concrete washout areas should be placed in  multiple locations for ease of use by concrete truck drivers. Concrete Truck Washout Procedures  l Washout of concrete truck drums shall be performed in designated concrete washout areas  only.  l Concrete washout from concrete pumper bins can be washed into concrete pumper trucks  and discharged into designated concrete washout areas or properly disposed of off-site. Concrete Washout Area Installation  l Concrete washout areas should be constructed as shown in the figures below, with a recom- mended minimum length and minimum width of 10 ft, but with sufficient quantity and volume  to contain all liquid and concrete waste generated by washout operations.  l Plastic lining material should be a minimum of 10 mil polyethylene sheeting and should be  free of holes, tears, or other defects that compromise the impermeability of the material.  l Lath and flagging should be commercial type.  l Liner seams shall be installed in accordance with manufacturers’ recommendations. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 365  l Soil base shall be prepared free of rocks or other debris that may cause tears or holes in the  plastic lining material. Maintenance Standards Inspection and Maintenance  l Inspect and verify that concrete washout areas are in place prior to the commencement of  concrete work.  l Once concrete wastes are washed into the designated washout area and allowed to  harden, the concrete should be broken up, removed, and disposed of per applicable solid  waste regulations. Dispose of hardened concrete on a regular basis.  l During periods of concrete work, inspect the concrete washout areas daily to verify con- tinued performance.  o Check overall condition and performance.  o Check remaining capacity (% full).  o If using self-installed concrete washout areas, verify plastic liners are intact and side- walls are not damaged.  o If using prefabricated containers, check for leaks.  l Maintain the concrete washout areas to provide adequate holding capacity with a minimum  freeboard of 12 inches.  l Concrete washout areas must be cleaned, or new concrete washout areas must be con- structed and ready for use once the concrete washout area is 75% full.  l If the concrete washout area is nearing capacity, vacuum and dispose of the waste material  in an approved manner.  l Do not discharge liquid or slurry to waterways, storm drains or directly onto ground.  l Do not discharge to the sanitary sewer without local approval.  l Place a secure, non-collapsing, non-water collecting cover over the concrete  washout area prior to predicted wet weather to prevent accumulation and overflow of  precipitation.  l Remove and dispose of hardened concrete and return the structure to a functional  condition. Concrete may be reused on-site or hauled away for disposal or recycling.  l When you remove materials from a self-installed concrete washout area, build a new struc- ture; or, if the previous structure is still intact, inspect for signs of weakening or damage, and  make any necessary repairs. Re-line the structure with new plastic after each cleaning. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 366 Removal of Concrete Washout Areas  l When concrete washout areas are no longer required for the work, the hardened concrete,  slurries and liquids shall be removed and properly disposed of.  l Materials used to construct concrete washout areas shall be removed from the site of the  work and disposed of or recycled.  l Holes, depressions or other ground disturbance caused by the removal of the concrete  washout areas shall be backfilled, repaired, and stabilized to prevent erosion. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 367 Figure II-4.7: Concrete Washout Area with Wood Planks 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 368 Figure II-4.8: Concrete Washout Area with Straw Bales 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 369 Figure II-4.9: Prefabricated Concrete Washout Container with Ramp 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 370  o For a 5 to 10 fps discharge velocity at the outlet, use 24-inch to 48-inch riprap. Min- imum thickness is 2 feet.  o For outlets at the base of steep slope pipes (pipe slope greater than 10 percent), use  an engineered energy dissipator.  o Filter fabric or erosion control blankets should always be used under riprap to prevent  scour and channel erosion. See BMP C122: Nets and Blankets.  l Bank stabilization, bioengineering, and habitat features may be required for disturbed  areas. This work may require a Hydraulic Project Approval (HPA) from the Washington  State Department of Fish and Wildlife. See I-2.14 Hydraulic Project Approvals. Maintenance Standards  l Inspect and repair as needed.  l Add rock as needed to maintain the intended function.  l Clean energy dissipator if sediment builds up. BMP C220: Inlet Protection Purpose Inlet protection prevents coarse sediment from entering drainage systems prior to permanent sta- bilization of the disturbed area. Conditions of Use Use inlet protection at inlets that are operational before permanent stabilization of the disturbed  areas that contribute runoff to the inlet. Provide protection for all storm drain inlets downslope and  within 500 feet of a disturbed or construction area, unless  those inlets are preceded by a sediment  trapping BMP. Also consider inlet protection for lawn and yard drains on new home construction. These small  and numerous drains coupled with lack of gutters can add significant amounts of sediment into the  roof drain system. If possible, delay installing lawn and yard drains until just before landscaping,  or cap these drains to prevent sediment from entering the system until completion of landscaping.  Provide 18-inches of sod around each finished lawn and yard drain. Table II-4.11: Storm Drain Inlet Protection lists several options for inlet protection. All of the meth- ods for inlet protection tend to plug and require a high frequency of maintenance. Limit con- tributing drainage areas for an individual inlet to one acre or less. If possible, provide emergency  overflows with additional end-of-pipe treatment where stormwater ponding would cause a hazard. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 400 Type of Inlet Pro- tection Emergency Overflow Applicable for Paved / Earthen Surfaces Conditions of Use Drop Inlet Protection Excavated  drop  inlet protection Yes, temporary  flooding may   occur Earthen Applicable for heavy flows. Easy   to maintain. Large area requirement:   30'x30'/acre Block  and gravel  drop inlet pro- tection Yes Paved or Earthen Applicable for heavy  concentrated flows.  Will not pond. Gravel and wire  drop inlet pro- tection No Paved or Earthen Applicable for  heavy concentrated flows.  Will pond. Can withstand traffic. Catch  basin filters Yes Paved or Earthen Frequent maintenance  required. Curb Inlet Protection Curb  inlet pro- tection with  wooden weir Small capacity  overflow Paved Used for sturdy, more compact  install- ation. Block and gravel  curb inlet pro- tection Yes Paved Sturdy, but  limited filtration. Culvert Inlet Protection Culvert  inlet sed- iment trap N/A N/A 18 month expected life. Table II-4.11: Storm Drain Inlet Protection Design and Installation Specifications Excavated Drop Inlet Protection Excavated drop inlet protection consists of an excavated impoundment around the storm drain  inlet. Sediment settles out of the stormwater prior to entering the storm drain. Design and install- ation specifications for excavated drop inlet protection include:  l Provide a depth of 1 to 2 feet as measured from the crest of the inlet structure.  l Side slopes of excavation should be no steeper than 2H:1V.  l Minimum volume of excavation is 35 cubic yards.  l Shape the excavation to fit the site, with the longest dimension oriented toward the longest  inflow area.  l Install provisions for draining to prevent standing water.  l Clear the area of all debris. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 401  l Grade the approach to the inlet uniformly.  l Drill weep holes into the side of the inlet.  l Protect weep holes with screen wire and washed aggregate.  l Seal weep holes when removing structure and stabilizing area.  l Build a temporary dike, if necessary, to the down slope side of the structure to prevent  bypass flow. Block and Gravel Filter A block and gravel filter is a barrier formed around the inlet with standard concrete blocks and  gravel. See Figure II-4.17: Block and Gravel Filter. Design and installation specifications for block  and gravel filters include:  l Provide a height of 1 to 2 feet above the inlet.  l Recess the first row of blocks 2-inches into the ground for stability.  l Support subsequent courses by placing a pressure treated wood (2x4) through the block  opening.  l Do not use mortar.  l Lay some blocks in the bottom row on their side to allow for dewatering the pool.  l Place hardware cloth or comparable wire mesh with 0.5-inch openings over all block open- ings.  l Place gravel to just below the top of blocks on slopes of 2H:1V or flatter.  l An alternative design is a gravel berm surrounding the inlet, as follows:  o Provide a slope of 3H:1V on the upstream side of the berm.  o Provide a slope of 2H:1V on the downstream side of the berm.  o Provide a 1-foot wide level rock area between the gravel berm and the inlet.  o Use rocks 3 inches in diameter or larger on the upstream slope of the berm.  o Use gravel 0.5 to 0.75 inch at a minimum thickness of 1-foot on the downstream  slope of the berm. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 402 Figure II-4.17: Block and Gravel Filter 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 403 Gravel and Wire Mesh Filter Gravel and wire mesh filters are gravel barriers placed over the top of the inlet. This method does  not provide an overflow. Design and installation specifications for gravel and wire mesh filters  include:  l Use a hardware cloth or comparable wire mesh with 0.5 inch openings.  o Place wire mesh over the drop inlet so that the wire extends a minimum of 1-foot bey- ond each side of the inlet structure.  o Overlap the strips if more than one strip of mesh is necessary.  l Place coarse aggregate over the wire mesh.  o Provide at least a 12-inch depth of aggregate over the entire inlet opening and extend  at least 18-inches on all sides. Catch Basin Filters Catch  basin filters are designed by manufacturers for construction sites. The limited sediment stor- age capacity increases the amount of inspection and maintenance required, which may be daily  for heavy sediment loads. To reduce maintenance requirements, combine a catch  basin filter with  another type of inlet protection. This type of inlet protection provides flow bypass without overflow  and therefore may be a better method for inlets located along active rights-of-way. Design and  installation specifications for catch basin filters include:  l Provides 5 cubic feet of storage.  l Requires dewatering provisions.  l Provides a high-flow bypass that will not clog under normal use at a construction site.  l Insert the catch  basin filter in the catch  basin just below the grating. Curb Inlet Protection with Wooden Weir Curb inlet protection with wooden weir is an option that consists of a barrier formed around a curb  inlet with a wooden frame and gravel. Design and installation specifications for curb inlet pro- tection with wooden weirs include:  l Use wire mesh with 0.5 inch openings.  l Use extra strength filter cloth.  l Construct a frame.  l Attach the wire and filter fabric to the frame.  l Pile coarse washed aggregate against the wire and fabric.  l Place weight on the frame anchors. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 404 Block and Gravel Curb Inlet Protection Block and gravel curb inlet protection is a barrier formed around a curb inlet with concrete blocks  and gravel. See Figure II-4.18: Block and Gravel Curb Inlet Protection. Design and installation spe- cifications for block and gravel curb inlet protection include:  l Use wire mesh with 0.5 inch openings.  l Place two concrete blocks on their sides abutting the curb at either side of the inlet opening.  These are spacer blocks.  l Place a 2x4 stud through the outer holes of each spacer block to align the front blocks.  l Place blocks on their sides across the front of the inlet and abutting the spacer blocks.  l Place wire mesh over the outside vertical face.  l Pile coarse aggregate against the wire to the top of the barrier. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 405 Figure II-4.18: Block and Gravel Curb Inlet Protection 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 406 Curb and Gutter Sediment Barrier A curb and gutter sediment barrier is a sandbag or rock berm (riprap and aggregate) 3 feet high  and 3 feet wide in a horseshoe shape. See Figure II-4.19: Curb and Gutter Barrier. Design and  installation specifications for curb and gutter sediment barriers include:  l Construct a horseshoe shaped berm, faced with coarse aggregate if using riprap, 3 feet  high and 3 feet wide, at least 2 feet from the inlet.  l Construct a horseshoe shaped sedimentation trap on the upstream side of the berm. Size  the trap to sediment trap standards for protecting a culvert inlet. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 407 Figure II-4.19: Curb and Gutter Barrier 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 408 Maintenance Standards  l Inspect all forms of inlet protection frequently, especially after storm events. Clean and  replace clogged catch basin filters. For rock and gravel filters, pull away the rocks from the  inlet and clean or replace. An alternative approach would be to use the clogged rock as fill  and put fresh rock around the inlet.  l Do not wash sediment into storm drains while cleaning. Spread all excavated material  evenly over the surrounding land area or stockpile and stabilize as appropriate. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did  not pass through the Technology Assessment Protocol – Ecology (TAPE) process. Local jur- isdictions may choose not to accept these products, or may require additional testing prior to con- sideration for local use. Products that Ecology has approved as functionally equivalent are  available for review on Ecology’s website at:  https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies BMP C231: Brush Barrier Purpose The purpose of brush barriers is to reduce the transport of coarse sediment from a construction  site by providing a temporary physical barrier to sediment and reducing the runoff velocities of  overland flow. Conditions of Use  l Brush barriers may be used downslope of disturbed areas that are less than one-quarter  acre.  l Brush barriers are not intended to treat concentrated flows, nor are they intended to treat  substantial amounts of overland flow. Any concentrated flows must be directed to a sed- iment trapping BMP. The only circumstance in which overland flow can be treated solely by  a brush barrier, rather than by a sediment trapping BMP, is when the area draining to the  barrier is small.  l Brush barriers should only be installed on contours. Design and Installation Specifications  l Height: 2 feet (minimum) to 5 feet (maximum).  l Width: 5 feet at base (minimum) to 15 feet (maximum). 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 409 BMP C233: Silt Fence Purpose Silt fence reduces the transport of coarse sediment from a construction site by providing a tem- porary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use Silt fence may be used downslope of all disturbed areas.  l Silt fence shall prevent sediment carried by runoff from going beneath, through, or over the  top of the silt fence, but shall allow the water to pass through the fence.  l Silt fence is not intended to treat concentrated flows, nor is it intended to treat substantial  amounts of overland flow. Convey any concentrated flows through the drainage system to a  sediment trapping BMP.  l Do not construct silt fences in streams or use in V-shaped ditches. Silt fences do not  provide an adequate method of silt control for anything deeper than sheet or overland flow. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 414 Figure II-4.22: Silt Fence 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 415 Design and Installation Specifications  l Use in combination with other construction stormwater BMPs.  l Maximum slope steepness (perpendicular to the silt fence line) 1H:1V.  l Maximum sheet or overland flow path length to the silt fence of 100 feet.  l Do not allow flows greater than 0.5 cfs.  l Use geotextile fabric that meets the following standards. All geotextile properties listed  below are minimum average roll values (i.e. the test result for any sampled roll in a lot shall  meet or exceed the values shown in Table II-4.12: Geotextile Fabric Standards for Silt  Fence): Geotextile Property Minimum Average Roll Value Polymeric  Mesh AOS  (ASTM D4751) 0.60 mm maximum for slit film  woven (#30 sieve).  0.30 mm  maximum for all other geotextile types (#50 sieve).  0.15 mm minimum for all fabric types (#100 sieve). Water  Permittivity  (ASTM D4491) 0.02 sec-1 minimum Grab  Tensile Strength  (ASTM D4632) 180 lbs minimum for extra  strength fabric.  100 lbs  minimum for standard strength fabric. Grab Tensile Strength  (ASTM D4632) 30% maximum Ultraviolet  Resistance  (ASTM D4355) 70%  minimum Table II-4.12: Geotextile Fabric Standards for Silt Fence  l Support standard strength geotextiles with wire mesh, chicken wire, 2-inch x 2-inch wire,  safety fence, or jute mesh to increase the strength of the geotextile. Silt fence materials are  available that have synthetic mesh backing attached.  l Silt fence material shall contain ultraviolet ray inhibitors and stabilizers to provide a min- imum of 6 months of expected usable construction life at a temperature range of 0°F to  120°F.  l 100% biodegradable silt fence is available that is strong, long lasting, and can be left in  place after the project is completed, if permitted by the local jurisdiction.  l Refer to Figure II-4.22: Silt Fence for standard silt fence details. Include the following Stand- ard Notes for silt fence on construction plans and specifications:  1. The Contractor shall install and maintain temporary silt fences at the locations shown  in the Plans. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 416  2. Construct silt fences in areas of clearing, grading, or drainage prior to starting those  activities.  3. The silt fence shall have a 2-foot min. and a 2.5-feet max. height above the original  ground surface.  4. The geotextile fabric shall be sewn together at the point of manufacture to form fabric  lengths as required. Locate all sewn seams at support posts. Alternatively, two sec- tions of silt fence can be overlapped, provided  that the overlap is long enough and  that the adjacent silt fence sections are close enough together to prevent silt laden  water from escaping through the fence at the overlap.  5. Attach the geotextile fabric on the up-slope side of the posts and secure with staples,  wire, or in accordance with the manufacturer's recommendations. Attach the geo- textile fabric to the posts in a manner that reduces the potential for tearing.  6. Support the geotextile fabric with wire or plastic mesh, dependent on the properties of  the geotextile selected for use. If wire or plastic mesh is used, fasten the mesh  securely to the up-slope side of the posts with the geotextile fabric up-slope of the  mesh.  7. Mesh support, if used, shall consist of steel wire with a maximum mesh spacing of 2- inches, or a prefabricated polymeric mesh. The strength of the wire or polymeric  mesh shall be equivalent to or greater than 180 lbs grab tensile strength. The poly- meric mesh must be as resistant to the same level of ultraviolet radiation as the geo- textile fabric it supports.  8. Bury the bottom of the geotextile fabric 4-inches min. below the ground surface. Back- fill and tamp soil in place over the buried portion of the geotextile fabric, so that no  flow can pass beneath the silt fence and scouring cannot occur. When wire or poly- meric back-up support mesh is used, the wire or polymeric mesh shall extend into the  ground 3-inches min.  9. Drive or place the silt fence posts into the ground 18-inches min. A 12–inch min.  depth is allowed if topsoil or other soft subgrade soil is not present and 18-inches can- not be reached. Increase fence post min. depths by 6 inches if the fence is located on  slopes of 3H:1V or steeper and the slope is perpendicular to the fence. If required  post depths cannot be obtained, the posts shall be adequately secured by bracing or  guying to prevent overturning of the fence due to sediment loading.  10. Use wood, steel or equivalent posts. The spacing of the support posts shall be a max- imum of 6 feet. Posts shall consist of one of the following:  l Wood with minimum dimensions of 2 inches by 2 inches by 3 feet. Wood shall  be free of defects such as knots, splits, or gouges.  l No. 6 steel rebar or larger.  l ASTM A 120 steel pipe with a minimum diameter of 1-inch.  l U, T, L, or C shape steel posts with a minimum weight of 1.35 lbs./ft. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 417  l Other steel posts having equivalent strength and bending resistance to the  post sizes listed above.  11. Locate silt fences on contour as much as possible, except at the ends of the fence,  where the fence shall be turned uphill such that the silt fence captures the runoff  water and prevents water from flowing around the end of the fence.  12. If the fence must cross contours, with the exception of the ends of the fence, place  check dams perpendicular to the back of the fence to minimize concentrated flow and  erosion. The slope of the fence line where contours must be crossed shall not be  steeper than 3H:1V.  l Check dams shall be approximately 1 foot deep at the back of the fence. Check  dams shall be continued perpendicular to the fence at the same elevation until  the top of the check dam intercepts the ground surface behind the fence.  l Check dams shall consist of crushed surfacing base course, gravel backfill for  walls, or shoulder ballast. Check dams shall be located every 10 feet along the  fence where the fence must cross contours.  l Refer to Figure II-4.23: Silt Fence Installation by Slicing Method for slicing method details.  The following are specifications for silt fence installation using the slicing method:  1. The base of both end posts must be at least 2 to 4 inches above the top of the geo- textile fabric on the middle posts for ditch checks to drain properly. Use a hand level  or string level, if necessary, to mark base points before installation.  2. Install posts 3 to 4 feet apart in critical retention areas and 6 to 7 feet apart in stand- ard applications.  3. Install posts 24 inches deep on the downstream side of the silt fence, and as close as  possible to the geotextile fabric, enabling posts to support the geotextile fabric from  upstream water pressure.  4. Install posts with the nipples facing away from the geotextile fabric.  5. Attach the geotextile fabric to each post with three ties, all spaced within the top 8  inches of the fabric. Attach each tie diagonally 45 degrees through the fabric, with  each puncture at least 1-inch vertically apart. Each tie should be positioned to hang  on a post nipple when tightening to prevent sagging.  6. Wrap approximately 6 inches of the geotextile fabric around the end posts and  secure with 3 ties.  7. No more than 24 inches of a 36 inch geotextile fabric is allowed above ground level.  8. Compact the soil immediately next to the geotextile fabric with the front wheel of the  tractor, skid steer, or roller exerting at least 60 pounds per square inch. Compact the  upstream side first and then each side twice for a total of four trips. Check and correct  the silt fence installation for any deviation before compaction. Use a flat-bladed  shovel to tuck the fabric deeper into the ground if necessary. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 418 Figure II-4.23: Silt Fence Installation by Slicing Method 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 419 Maintenance Standards  l Repair any damage immediately.  l Intercept and convey all evident concentrated flows uphill of the silt fence to a sediment trap- ping BMP.  l Check the uphill side of the silt fence for signs of the fence clogging and acting as a barrier  to flow and then causing channelization of flows parallel to the fence. If this occurs, replace  the fence and remove the trapped sediment.  l Remove sediment deposits when the deposit reaches approximately one-third the height of  the silt fence, or install a second silt fence.  l Replace geotextile fabric that has deteriorated due to ultraviolet breakdown. BMP C234: Vegetated Strip Purpose Vegetated strips reduce the transport of coarse sediment from a construction site by providing a  physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use  l Vegetated strips may be used downslope of all disturbed areas.  l Vegetated strips are not intended to treat concentrated flows, nor are they intended to treat  substantial amounts of overland flow. Any concentrated flows must be conveyed through  the drainage system to BMP C241: Sediment Pond (Temporary) or other sediment trapping  BMP. The only circumstance in which overland flow can be treated solely by a vegetated  strip, rather than by a sediment trapping BMP, is when the following criteria are met (see  Table II-4.13: Contributing Drainage Area for Vegetated Strips): Average Contributing Area Slope Average Contributing Area Per- cent Slope Maximum Contributing Area Flowpath Length 1.5H : 1V or flatter 67% or flatter 100 feet 2H : 1V or  flatter 50% or flatter 115 feet 4H : 1V or  flatter 25% or flatter 150  feet 6H : 1V or  flatter 16.7% or flatter 200  feet 10H : 1V or  flatter 10% or flatter 250  feet Table II-4.13: Contributing Drainage Area for Vegetated Strips 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 420 Design and Installation Specifications  l The vegetated strip shall consist of a continuous strip of dense vegetation with topsoil for a  minimum length of 25 feet along the flow path. Grass-covered, landscaped areas are gen- erally not adequate because the volume of sediment overwhelms the grass. Ideally, veget- ated strips shall consist of undisturbed native growth with a well-developed soil that allows  for infiltration of runoff.  l The slope within the vegetated strip shall not exceed 4H:1V.  l The uphill boundary of the vegetated strip shall be delineated with clearing limits. Maintenance Standards  l Any areas damaged by erosion or construction activity shall be seeded immediately and  protected by mulch.  l If more than 5 feet of the original vegetated strip width has had vegetation removed or is  being eroded, sod must be installed.  l If there are indications that concentrated flows are traveling across the vegetated strip,  stormwater runoff controls must be installed to reduce the flows entering the vegetated  strip, or additional perimeter protection must be installed. BMP C235: Wattles Purpose Wattles are temporary erosion and sediment control barriers consisting of straw, compost, or  other material that is wrapped in netting made of natural plant fiber or similar encasing material.  They reduce the velocity and can spread the flow of rill and sheet runoff, and can capture and  retain sediment. Conditions of Use  l Use wattles:  o In disturbed areas that require immediate erosion protection.  o On exposed soils during the period of short construction delays, or over winter  months.  o On slopes requiring stabilization until permanent vegetation can be established.  l The material used dictates the effectiveness period of the wattle. Generally, wattles are  effective for one to two seasons.  l Prevent rilling beneath wattles by entrenching and overlapping wattles to prevent water  from passing between them. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 421 Design Criteria  l Wattles shall consist of cylinders of plant material such as weed-free straw, coir, wood  chips, excelsior, or wood fiber or shavings encased within netting made of natural plant  fibers unaltered by synthetic materials.  l See Figure II-4.24: Wattles for typical construction details.  l Wattles are typically 8 to 10 inches in diameter and 25 to 30 feet in length.   l Install wattles perpendicular to the flow direction and parallel to the slope contour.  l Place wattles in shallow trenches, staked along the contour of disturbed or newly con- structed slopes. Dig narrow trenches across the slope (on contour) to a depth of 3 to 5  inches on clay soils and soils with gradual slopes. On loose soils, steep slopes, and areas  with high rainfall, the trenches should be dug to a depth of 5 to 7 inches, or 1/2 to 2/3 of the  thickness of the wattle.  l Start building trenches and installing wattles from the base of the slope and work up.  Spread excavated material evenly along the uphill slope and compact it using hand tamping  or other methods.  l Construct trenches at intervals of 10 to 25 feet depending on the steepness of the slope,  soil type, and rainfall. The steeper the slope the closer together the trenches.  l Install the wattles snugly into the trenches and overlap the ends of adjacent wattles 12  inches behind one another.  l Install stakes at each end of the wattle, and at 4 foot centers along entire length of wattle.  l If required, install pilot holes for the stakes using a straight bar to drive holes through the  wattle and into the soil.  l Wooden stakes should be approximately 0.75 x 0.75 x 24 inches minimum. Willow cuttings  or 3/8 inch rebar can also be used for stakes.  l Stakes should be driven through the middle of the wattle, leaving 2 to 3 inches of the stake  protruding above the wattle. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 422 Figure II-4.24: Wattles 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 423 Maintenance Standards  l Wattles may require maintenance to ensure they are in contact with soil and thoroughly  entrenched, especially after significant rainfall on steep sandy soils.  l Inspect the slope after significant storms and repair any areas where wattles are not tightly  abutted or water has scoured beneath the wattles. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did  not pass through the Technology Assessment Protocol – Ecology (TAPE) process. Local jur- isdictions may choose not to accept these products, or may require additional testing prior to con- sideration for local use. Products that Ecology has approved as functionally equivalent are  available for review on Ecology’s website at:  https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies BMP C236: Vegetative Filtration Purpose Vegetative filtration as a BMP is used in conjunction with detention storage in the form of portable  tanks or BMP C241: Sediment Pond (Temporary), BMP C206: Level Spreader, and a pumping  system with surface intake. Vegetative filtration improves turbidity levels of stormwater discharges  by filtering runoff through existing vegetation where undisturbed forest floor duff layer or estab- lished lawn with thatch layer are present.  Vegetative filtration can also be used to infiltrate dewa- tering waste from foundations, vaults, and trenches as long as runoff does not occur. Conditions of Use  l For every 5 acres of disturbed soil, use 1 acre of grass field, farm pasture, or wooded area.  Reduce or increase this area depending on project size, groundwater table height, and  other site conditions.  l Wetlands shall not be used for vegetative filtration.  l Do not use this BMP in areas with a high groundwater table, or in areas that will have a high  seasonal groundwater table during the use of this BMP.  l This BMP may be less effective on soils that prevent the infiltration of the water, such as  hard till.  l Using other effective source control measures throughout a construction site will prevent  the generation of additional highly turbid water and may reduce the time period or area  need for this BMP.  l Stop distributing water into the vegetated filtration area if standing water or erosion results. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 424 Maintenance Standards  l Monitor the spray field on a daily basis to ensure that over saturation of any portion of the  field does not occur at any time. The presence of standing puddles of water or creation of  concentrated flows visually signify that over saturation of the field has occurred.  l Monitor the vegetated spray field all the way down to the nearest surface water, or farthest  spray area, to ensure that the water has not caused overland or concentrated flows, and  has not created erosion around the spray nozzle(s).  l Do not exceed water quality standards for turbidity.  l Ecology recommends that a separate inspection log be developed, maintained, and kept  with the existing site logbook to aid the operator conducting inspections. This separate  “Field Filtration Logbook” can also aid in demonstrating compliance with permit conditions.  l Inspect the spray nozzles daily, at a minimum, for leaks and plugging from sediment  particles.  l If erosion, concentrated flows, or over saturation of the field occurs, rotate the use of  branches or spray heads or move the branches to a new field location.  l Check all branches and the manifold for unintended leaks. BMP C240: Sediment Trap Purpose A sediment trap is a small temporary ponding area with a gravel outlet used to collect and store  sediment from sites during construction. Sediment traps, along with other perimeter controls, shall  be installed before any land disturbance takes place in the contributing drainage area. Conditions of Use  l Sediment traps are intended for use on sites where the contributing drainage area is less  than 3 acres, with no unusual drainage features, and a projected build-out time of 6 months  or less. The sediment trap is a temporary measure (with a design life of approximately 6  months) and shall be maintained until the contributing drainage area is permanently pro- tected against erosion by vegetation and/or structures.  l Sediment traps are only effective in removing sediment down to about the medium silt size  fraction. Runoff with sediment of finer grades (fine silt and clay) will pass through untreated,  emphasizing the need to control erosion to the maximum extent first.  l Projects that are constructing permanent Flow Control BMPs, or permanent Runoff Treat- ment BMPs that use ponding for treatment, may use the rough-graded or final-graded per- manent BMP footprint for the temporary sediment trap. When permanent BMP footprints  are used as temporary sediment traps, the surface area requirement of the sediment trap  must be met. If the surface area requirement of the sediment trap is larger than the surface  area of the permanent BMP, then the sediment trap shall be enlarged beyond the  2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 427 permanent BMP footprint to comply with the surface area requirement.  l A floating pond skimmer may be used for the sediment trap outlet if approved by the Local  Permitting Authority.  l Sediment traps may not be feasible on utility projects due to the limited work space or the  short-term nature of the work. Portable tanks may be used in place of sediment traps for util- ity projects. Design and Installation Specifications  l See Figure II-4.26: Cross Section of Sediment Trap and Figure II-4.27: Sediment Trap Out- let for details.  l To determine the sediment trap geometry, first calculate the design surface area (SA) of the  trap, measured at the invert of the weir. Use the following equation: SA = FS * (Q2/Vs) where: SA = Design surface area of the trap (square feet) FS = A safety factor of 2 to account for non-ideal settling. Q2 = The peak volumetric flow rate (cubic feet per second), calculated using one of the fol- lowing options:  o Option 1 - Single Event Hydrograph Method The peak volumetric flow rate calculated using a 10-minute time step from a Type 1A,  2-year, 24-hour frequency storm for the developed condition. The 10-year peak volu- metric flow rate shall be used if the project size, expected timing and duration of con- struction, or downstream conditions warrant a higher level of protection.   o Option 2 - The Rational Method For construction sites that are less than 1 acre, the peak volumetric flow rate cal- culated using the Rational Method. Vs = The settling velocity of the soil particle of interest. The 0.02 mm (medium silt) particle  with an assumed density of 2.65 g/cm3 has been selected as the particle of interest and has  a settling velocity (Vs) of 0.00096 ft/sec.   Therefore, the equation for computing sediment trap surface area becomes: SA  = 2 x Q2/0.00096  or 2080 square feet per cfs of inflow   2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 428  l Sediment trap depth shall be 3.5 feet minimum from the bottom of the trap to the top of the  overflow weir.  l To aid in determining sediment depth, all sediment traps shall have a staff gauge with a  prominent mark 1 foot above the bottom of the trap.  l Design the discharge from the sediment trap by using the guidance for discharge from tem- porary sediment ponds in BMP C241: Sediment Pond (Temporary). Maintenance Standards  l Sediment shall be removed from the trap when it reaches 1 foot in depth.  l Any damage to the trap embankments or slopes shall be repaired. 2024 Stormwater Management Manual for Western Washington Volume II -Chapter 4 -Page 429 feet tall. Tree Location and Planting Criteria Trees shall be sited according to sun, soil, and moisture requirements. Planting locations shall be  selected to ensure that sight distances and appropriate setbacks are maintained given mature  height, size, and rooting depths. Similar to retained trees, Flow Control credit for newly planted  trees depends upon proximity to ground level impervious surfaces.  To receive a credit, the tree must be planted on the development site and within 20 feet of new  and/or replaced ground level impervious surfaces (e.g. driveway, patio, or parking lot). Distance  from impervious surfaces is measured from the edge of the surface to the center of the tree at  ground level. To help ensure tree survival and canopy coverage, the minimum tree spacing for  newly planted trees shall accommodate mature tree spread. Plant in appropriate areas characterized by quality soils and adequate soil volume for the appro- priate tree species. (Urban, 2008) recommends a minimum depth for planting soil of 30 to  48 inches. This depth should extend for a 10-foot radius around the tree in lawn areas. Adequate  soil volume  depends on soil type, water availability and tree size (crown projection or trunk dia- meter), at a rate of 1 to 3 cf of soil per 1 sf of tree crown area. For trees without irrigation, soil  volume should be high. Planting beds should be of an adequate size for the tree selected and special attention should be  given to increasing soil and rooting volume. Where significant snow storage is anticipated, trees  should be protected and planted away from significant snow accumulations. Plowed snow is  denser and can be heavily laden with deicing chemicals and salts - either of which can be det- rimental to healthy plant and tree growth. In parking areas where snow accumulation can be sig- nificant, parking and drive lanes should be arranged to allow ease of snow plowing and to  facilitate the protection of planting areas.  Multiple strategies for increasing the soil depth and volume to promote healthy trees are  described below.  Irrigation Provisions shall be made for supplemental irrigation during the first three growing seasons after  installation to help ensure tree survival. Newly Planted Tree Flow Control Credit Flow Control credits for newly planted trees are provided in Table V-12.2: Flow Control Credits for  Newly Planted Trees by tree type. These credits can be applied to reduce the impervious or other  hard surface area requiring Flow Control. Credits range from 20 to 50 square feet (SF) per tree. 2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1067 Tree Type Credit Evergreen 50 SF  per tree Deciduous 20 SF  per tree Table V-12.2: Flow Control Credits for Newly Planted Trees Impervious/Hard Surface Area Mitigated =  Σ Number of Trees x Credit (sq. ft.) Flow Control credits are not applicable to trees in native vegetation areas used for dispersion  BMPs or other Flow Control credit. Credits are also not applicable to trees in planter boxes. The  total tree credit for newly planted trees shall not exceed 25% of the impervious or other hard sur- face area requiring mitigation. Strategies for Increasing the Soil Depth and Volume to Promote Healthy Trees Use of Soil Amendment for Trees If possible, stockpile and reuse existing soils for tree planting. For adequate drainage and tree  health, (Urban, 2008) recommends avoiding topsoil that has more than 35% clay, 45% silt, or 25%  fine sand. Loam, sandy loam, and sandy clay loam provide good textural classifications for sup- porting healthy tree growth. If stormwater is directed to the tree planting area, a designed soil mix may be necessary to  achieve adequate infiltration and drain-down characteristics.  A variety of materials are available to amend existing soils or design a specific soil mix. Mineral  soil amendments alter soil texture and improve infiltration and water holding characteristics. Com- mon materials used in tree planters and planting areas include sand, expanded shale, clay and  slate, and diatomaceous earth (see (Urban, 2008) for detailed descriptions for using mineral  amendments). Where the native soils are low in organic matter, biologic and organic amendments should be  used to improve organic matter content, infiltration capability, nutrient availability, soil biota, and  cation exchange capacity, as appropriate. Biologic amendments include mycorrhizal fungi spores,  kelp extracts, humic acids, organic fertilizers, and compost tea. If tree planting soil is poor quality,  biologic amendments generally only offer a temporary improvement for tree growth. Increasing Soil and Rooting Volume: Soil Cell Systems Soil cell systems are modular frames (base and pillar) with a deck that supports the pavement  above and creates large spaces for uncompacted soil and tree roots. DeepRoot Green Infra- structure developed the Silva Cell, which is a common type of rigid load-bearing soil cell for trees.  The decks are often designed for AASHTO H-20 loading (see Figure V-12.3: Silva Cell Filled With  Bioretention Soil Mix and Topped With Permeable Pavers). Many utilities can be installed within  and through the cells; however, utilities require planning and careful consideration. Many types of  2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1068 soil can be used to fill the cells for a rooting medium, including imported soils designed for the spe- cific tree or excavated soils (including heavier dense soils with higher clay content) amended with  compost if necessary (ASLA, 2010). An advantage with soil cells is that > 90% of the volume cre- ated by the cell is available for soil. 2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1069 Figure V-12.3: Silva Cell Filled With Bioretention Soil Mix and Topped With Permeable Pavers   2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1070 Increasing Soil and Rooting Volume: Structural Soils Structural soils provide a porous growth medium and structural support for sidewalks and street  edges.  Structural soils are a mix of mineral soil (typically a loam or clay loam with ≥ 20% clay for  adequate water and nutrient holding capacity) and coarse aggregate (typically uniformly graded  ¾-inch to 1½-inch angular crushed rock) that, after compaction, maintains porosity (typically 25%  to 30%) and infiltration capacity (typically > 20 inches per hour [in/hr]). Current research and  installation experience has resulted in guidelines for designing with structural soil including the fol- lowing:  l Structural soil can be used under all or part of the paved surfaces adjacent to trees to  provide the necessary soil volume. Where structural soil is placed adjacent to open graded  base aggregate, geotextile should be used to prevent migration of the fine aggregate in the  structural soil to the more open graded material (Bassuk et al., 2005).  l Soil depth: 24 inches (minimum) to 36 inches (recommended) (Bassuk et al., 2005).  l Compaction: 95% Proctor (Bassuk et al., 2005).  l Tree pit opening: If the tree pit opening is at least 5 feet x 5 feet, a well-drained top soil can  be used in the planting area. If the opening is smaller, structural soil can be used imme- diately under and up to the root ball (Bassuk et al., 2005).  l Available soil: The structural aggregate uses approximately 80% of the available space;  therefore, approximately 20% of the total planting volume is available soil to support tree  growth.  l Soil volume: 2 cf for each 1 sf of crown projection (mature tree) is a well-accepted industry  standard. Because the structural aggregate uses approximately 80% of the available  space, 10 cf of structural soil for each 1 sf of crown projection (mature tree) may be needed.  l Planters with impervious walls: Openings filled with uncompacted soil can be used to  allow roots to access surrounding structural soil (Bassuk et al., 2005).  l Tree species: Use species that are tolerant of well-drained soil and periodic flooding.  l Drain-down: Structural soil reservoir should drain down within 48 hours to encourage good  root distribution through planting pit (Bartens et al., 2009). Many structural soils are proprietary mixes distributed through licensed providers. Sand-based  structural soil (SBSS) is an urban tree planting system that is not proprietary. SBSS consists of a  uniform gradation of medium to coarse sand (typically 30 inches deep) mixed with compost (2% to  3% by volume) and loam to achieve approximately 8% to 10% silt by volume. In general, the saturated hydraulic conductivity should be approximately 4 to 6 in/hr. The uniformly  graded sand maintains porosity and infiltration capacity when compacted; however, the load-bear- ing capacity of the mix is reduced due to the uniform particle size. Accordingly, crushed rock is  used between the sand and surface wearing course. Structural soils can be used in conjunction with permeable pavement (Haffner et al., 2007). 2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1071 Contact authorized distributors and see (Day and Dickinson, 2008) for guidelines on specific struc- tural soil products. Increasing Soil and Rooting Volume: Creating Root Paths Root paths are a technique to connect planting areas, interconnect tree roots, or guide roots out of  confined areas to soil under pavement or adjacent to paved area that has the capability to support  root growth (e.g. uncompacted, adequately drained loams). The actual root paths add only small  amounts of rooting volume. The path trenches are typically 4 inches wide by 12 inches deep and  filled with a strip drain board and topsoil. Root paths are excavated with a standard trenching  machine, placed approximately 4 feet on center, and compacted with a vibrating plate compactor  to retain subgrade structural integrity for pavement. The trenches should be extended into the tree  planting pit a minimum of 1 foot and preferably within a few inches of the tree root ball (Urban,  2008). Increasing Soil and Rooting Volume: Connecting to Adjacent Soil Volume Soil trenches are used to increase soil and root volume, connect to other tree planting areas, and  importantly, connect to larger areas with soil that have the capability to support root growth (e.g.  uncompacted, adequately drained loams). The trenches are typically 5 feet wide with sloped sides  for structural integrity and filled with topsoil or a designed soil mix. The installed soil is lightly com- pacted (e.g. 80% Proctor) with a gravel base placed on top of the soil to increase support for the  sidewalk. The sidewalk is reinforced with rebar and thickened to span the soil trench. The  thickened portion should extend a minimum 18 inches onto the adjacent compacted subgrade. An  underdrain may be necessary depending on subgrade soil with low infiltration rates and if storm- water is directed to the tree planting area. Consult with a licensed professional for drainage  requirements. Provide subsurface irrigation conduit preferably from stormwater or harvested  water in areas with < 30 inches of annual precipitation (Urban, 2008). Construction Criteria Protecting new and existing trees and minimizing soil compaction during construction is essential  to maintain infiltration and adequate growing characteristics in the built environment. This is par- ticularly true in urban areas. The designer should pay close attention to construction sequencing  and material staging from the planning through construction phases as well as tree protection  measures after the project is completed. It is also important to protect construction site soils from  compaction and contamination in tree planting areas.  See the construction criteria in BMP T5.13: Post-Construction Soil Quality and Depth for addi- tional guidelines. Operation and Maintenance Criteria If a tree is dead, damaged, or declining, the tree should be replaced per the planting plan (either  with the same type of tree or a substitute that is acceptable to the local jurisdiction). There are a vast number of resources associated with proper tree maintenance practices, includ- ing: 2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1072  l Washington State University staff  have prepared guidance for general tree maintenance  that can be found on Washington State University’s website: http://www.wsu.edu/  l Additional sources of species-specific maintenance guidance can be found in The New Sun- set Western Garden Book (Sunset Magazine, 2012).  l The American National Standards Institute (ANSI) ANSI A300 Tree Care Standards. Runoff Model Representation If the design criteria for this BMP are followed, the total impervious/hard surface areas entered  into the runoff model may be reduced by the amount indicated in the design criteria above. Botanical Name Common Name Height Spread Comments Native Tree (Y/N) Large Group Abies  grandis Grand  Fir 100 35 Grows  at 0-1500 m in  moist conifer forests.Y Abies  procera Noble  Fir 90 30  N Acer  freemanii  'Autumn Blaze' Autumn  Blaze  Maple 50 40  N Acer  macrophyllum Big  Leaf Maple 100 80 Very  large native.Y Acer  platanoides  'Emerald Queen'  Emerald  Queen  Norway Maple 50 40  N Acer  saccharum  'Bonfire'  Bonfire  Sugar  Maple 50 40 Fastest  growing  sugar maple.N Acer  saccharum  'Commemoration'  Commemoration   Sugar Maple 50 35 Resistant  to leaf tat- ter.N Acer  saccharum  'Legacy'  Legacy  Sugar  Maple 50 35 Limited  use - where  sugar maple is  desired in standard  planting strips N Aesculus  flava Yellow  Buckeye 70 40 Yellow  flowers - least  susceptible to leaf  blotch - large fruit N Alnus  rubra Red  Alder 70 35 Nitrogen  fixing.Y Cercidiphyllum   japonicum Katsura  Tree 40 40 Needs  lots of water  when young N Table V-12.3: Recommended Newly Planted Tree Species for Flow Control Credit 2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1073 Botanical Name Common Name Height Spread Comments Native Tree (Y/N) Fagus  sylvatica Green  Beech 50 40 Silvery-grey  bark.N Fagus  sylvatica  'Asplenifolia'Fernleaf  Beech 60 60 Beautiful  cut leaf N Fraxinus  latifolia Oregon  Ash 60 35 Only  native ash in  PNW.Y Fraxinus   pennsylvanica 'Urb- anite' Urbanite  Ash 50 40 Tolerant  of city con- ditions.N Gymnocladus   dioicus 'Espresso' Espresso  Kentucky  Coffeetree 50 35 Very  coarse branches  - extremely large bi- pinnately compound  leaf. N Liriodendron   tulipifera Tulip  Tree 60 30 Fast-growing  tree.N Nothofagus  ant- arctica Antarctic  Beech 50 35 Rugged  twisted  branching and petite  foliage. N Picea  sitchensis Sitka  Spruce 100 30 Native  environment is  characterized by cool,  moist maritime cli- mate. Y Pinus  monticola Western  White  Pine 100 35 Occurs  in lowland fog  forests or on moist  mountain soils -  primary host. Y Platanus  x acerifolia  'Bloodgood' Bloodgood  London  Planetre 50 40 More  anthracnose  resistant - needs  space. N Platanus  x acerifolia  'Yarwood'  Yarwood  London  Planetree 50 40 High  resistance to  powdery mildew.N Psuedotsuga  men- ziesii Douglas  Fir 150 35  Y Quercus  bicolor Swamp  White Oak 45 45 Shaggy  peeling bark.N Quercus  coccinea Scarlet  Oak 50 40 Best  oak for fall color.N Quercus  garryana Oregon  Oak 45 40 Native  to Pacific  Northwest.Y Table V-12.3: Recommended Newly Planted Tree Species for Flow Control Credit (continued) 2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1074 Botanical Name Common Name Height Spread Comments Native Tree (Y/N) Quercus  imbricaria Shingle  Oak 60 50 Nice  summer foliage -  leaves can persist  throughout the winter. N Quercus   muhlenbergii Chestnut  Oak 60 50 Coarsely  toothed leaf.N Quercus  robur English  Oak 50 40 Large,  sturdy tree.N Quercus  rubra Red  Oak 50 45 Fast  growing oak -  needs space.N Quercus  velutina Black  Oak 60 50  N Thuja  plicata Western  Red  Cedar 125 40 Growth  is stunted on  dry soils.Y Tsuga  heterophylla Western  Hemlock 130 30  Y Ulmus  'Homestead'Homestead  Elm 60 35  N Ulmus  'Pioneer'Pioneer  Elm 60 50 Resistant  to Dutch  elm disease.N Ulmus  parvifolia  'Emer II'Allee  Elm 50 35 Exfoliating  bark and  nice fall color.N Zelkova  serrata  'Greenvase' Green  Vase  Zelkova 50 40 Vigorous.N Medium/Large Group Acer  campestre Hedge  Maple 30 30  N Acer  campestre  'Evelyn' Queen  Elizabeth  Hedge Maple 35 30 More  upright branch- ing than the species.N Acer  miyabei 'Mor- ton'State  Street Maple 45 30  N Acer  platanoides  'Parkway' Parkway  Norway  Maple 40 25 Tolerant  of verticillium  wilt.N Acer  pseudo- platanus 'Atrop- urpureum' Spaethii  Maple 40 30 Leaves  green on top  purple underneath.N Acer  saccharum  'Green Mountain' Green  Mountain  Sugar Maple 45 35 Reliable  fall color.N Aesculus  x carnea Briottii'  Red Horse- chestnut 30 35 Resists  heat and  drought better than N Table V-12.3: Recommended Newly Planted Tree Species for Flow Control Credit (continued) 2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1075 Botanical Name Common Name Height Spread Comments Native Tree (Y/N) other horsechestnuts Betula  albosinensis  var septentrionalis Chinese  Red Birch 45 35 White/pink  peeling  bark.N Betula  jacquemontii Jacquemontii  Birch 40 30 White  bark makes for  good winter interest -  best for aphid res- istance. N Betula  papyrifera Paper  Birch 60 35 High  susceptibility to  aphid infestation.Y Chamaecyparis   pisifera Sawara  Cypress 45 25 Special  site approval  needed- many cul- tivars available. N Corylus  colurna Turkish  Filbert 40 25 Tight,  formal, dense  crown - not for high  pedestrian areas. N Eucommia  ulmoides Hardy  Rubber Tree 50 40 Dark  green shiny  leaves.N Fagus  sylvatica  'Rohanii' Purple  Oak Leaf  Beech 50 30 Attractive  purple  leaves with wavy mar- gins. N Fraxinus  americana  'Autumn Applause' Autumn  Applause  Ash 40 25 Compact  tree -  reportedly seedless.N Fraxinus  americana  'Empire'Empire  Ash 50 25 Use  for areas adja- cent to taller buildings  when ash is desired. N Fraxinus   pennsylvanica 'Pat- more' Patmore  Ash 45 35 Extremely  hardy, may  be seedless.N Ginko  biloba  'Autumn Gold' Autumn  Gold  Ginkgo 45 35 Narrow  when young.N Halesia  monticola Mountain  Silverbell 45 25 Attractive  small white  flower.N Koelreuteria  pan- iculata Goldenrain  Tree 30 30 Midsummer  bloom- ing.N Liquidambar  styra- ciflua 'Rotundiloba' Rotundiloba  Sweet- gum 45 25 Only  sweetgum that  is entirely fruitless. N Table V-12.3: Recommended Newly Planted Tree Species for Flow Control Credit (continued) 2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1076 Botanical Name Common Name Height Spread Comments Native Tree (Y/N) Smooth rounded leaf  lobes. Magnolia  denudata Yulan  Magnolia 40 40 6" fragrant white blos- soms in spring.N Metasequoia   glyptostroboides Dawn  Redwood 50 25 Fast  growing decidu- ous conifer.N Nyssa  sylvatica Tupelo 60 20 Handsomely  chunky  bark.N Phellodendron   amurense 'Macho'Macho Cork Tree 40 40 Male  selection - fruit- less - another good  variety is 'His  Majesty'. N Pinus  nigra Austrian  Pine 45 25 Special  site approval  needed - fairly tol- erant of heat, pol- lution, urban N Pinus  pinea Italian  Stone Pine 40 30 Special  site approval  needed.N Populus  trem- uloides Quaking  Aspen 50 30  Y Pyrus  calleryana  'Aristocrat'Aristocrat  Pear 40 30 Good  branch angles -  one of the tallest  pears. N Quercus  frainetto Italian  Oak 50 30 Drought  reistant.N Quercus  robur 'fas- tigiata'Skyrocket  Oak 40 15 Columnar  variety of  oak.N Salix  lasiandra Pacific  Willow 40 30  Y Sophora  japonica  'Regent' Japanese   Pagodatree 50 40 Can  have trunk  canker or twig blight.N Taxodium  distichum Bald  Cypress 5 30 A  deciduous conifer.N Taxodium  distichum  'Mickelson' Shawnee  Brave  Bald Cypress 55 20 Deciduous  conifer -  tolerates city con- ditions. N Tilia  americana  'Redmond'Redmond  Linden 45 30 Pyramidal,  needs  water.N Table V-12.3: Recommended Newly Planted Tree Species for Flow Control Credit (continued) 2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1077 Botanical Name Common Name Height Spread Comments Native Tree (Y/N) Tilia  cordata 'Green- spire'Greenspire  Linden 40 30 Symmetrical,  pyr- amidal form.N Zelkova  serrata 'Vil- lage Green'  Village  Green  Zelkova 40 38  N Medium/Small Group Acer nigrum 'Green  Column' Green Column  Black Maple 50 10 Good close to build- ings.N Acer platanoides  'Columnar' Columnar Norway  Maple 40 15 Good close to build- ings.N Acer rubrum 'Bow- hall'Bowhall Maple 40 15  N Acer rubrum  'Karpick'Karpick Maple 35-40 20 May work under very  high power lines with  arborist's approval. N Acer rubrum  'Scarsen' Scarlet Sentinel  Maple 40 20  N Acer  truncatum x A.  platanoides 'Keiths- form' Norwegian  Sunset  Maple 35 25 Limited  use under  wires.N Acer  truncatum x A.  platanoides 'War- renred' Pacific  Sunset  Maple 30 25 Limited  use under  wires.N Alnus  sinuata Sitka  Alder 40 25 Prefers  a heavy moist  soil - usually found  above 3000'. Y Carpinus  betulus 'Fastigiata' Pyr- amidal European  Hornbeam 35 15 Broadens  when older.N Cladrastis  kentukea Yellowwood 40 40 White  flowers in  spring, resembling  wisteria flower. N Cornus  controversa  'June Snow'Giant  Dogwood 40 30 Large  white flower  clusters that appear  in June. N Crataegus  crus-galli  'Inermis' Thornless  Cock- spur Hawthorne 25 30 Red  persistent fruit.N Table V-12.3: Recommended Newly Planted Tree Species for Flow Control Credit (continued) 2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1078 Botanical Name Common Name Height Spread Comments Native Tree (Y/N) Crataegus  phaen- opyrum Washington   Hawthorne 25 20 Thorny.N Crataegus  suks- dorfii Suksdorf's   Hawthorne 30 25 Shorter  spines than  C. Douglasii.Y Crataegus  x lavalii Lavalle  Hawthorne 28 20 Thorns  on younger  trees.N Davidia  involucrata Dove  Tree 40 30 Large,  unique white  flowers in May.N Ginko  biloba 'Prin- ceton Sentry' Princeton  Sentry  Ginkgo 40 15 Very  narrow growth.N Halesia  tetraptera Carolina  Silverbell 35 30 Attractive  bark for sea- sonal interest.N Libocedrus  decur- rens Incense  Cedar 35 20 Special  site approval  needed.N Liquidambar  styra- ciflua Moraine  Sweetgum 40 20 Light  green foliage.  More compact than  other varieties. N Maackia  amurensis Amur  Maackia 30 20 Attractive  bark and  summer flowers -  grows in tough con- ditions. N Magnolia  'Elizabeth'Elizabeth  Magnolia 30 20 Yellow  Flowers.N Magnolia  'Galaxy'Galaxy  Magnolia 35 25 Reddish-purple   flowers in spring.N Magnolia  gran- diflora 'Victoria' Victoria  Evergreen  Magnolia 25 20  N Magnolia  Kobus Wada's  Memory  Magnolia 35 20 Does  not flower well  when young.N Ostrya  virginiana Ironwood 40 25 Hop  like fruit.N Parrotia  persica Persian  Parrotia 30 20 Select  or prune for  single stem; can be  multi-trunked. N Pinus  densiflora  'Umbraculifera'Umbrella  Pine 25 20 Special  site approval  needed.N Prunus  x yedoensis Akebono  Flowering 25 25  N Table V-12.3: Recommended Newly Planted Tree Species for Flow Control Credit (continued) 2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1079 Botanical Name Common Name Height Spread Comments Native Tree (Y/N) 'Akebono'Cherry Pterostyrax  hispida Fragrant  Epaulette  Tree 40 35 Pendulous  creamy  white flowers - fra- grant. N Pyrus  calleryana  'Cambridge'Cambridge  Pear 40 15 Narrow  tree with good  branch angles and  form. N Pyrus  calleryana  'Glen's Form' Chanticleer  or  Cleveland Select  Pear 40 15 Vigorous.N Pyrus  calleryana  'Redspire'Redspire  Pear 35 25 Pyramidal.N Quercus  'Crim- schmidt'Crimson  Spire Oak 45 15 Hard  to find.N Robinia  x ambigua Pink  Idaho Locust 35 25 Fragrant  flowers.N Sciadopitys  ver- ticillata Japanese  Umbrella  Pine 30 20 Grows  slowly -  pristine evergreen  foliage - special site  approval. N Sorbus  alnifolia Korean  Mountain  Ash 40 30 Simple  leaves. Beau- tiful pink-red fruit -  may be short lived. N Sorbus  aucuparia  'Mitchred' Cardinal  Royal Mt.  Ash 35 20 Bright  red berries.N Sorbus  x hybridia Oakleaf  Royal Mt.  Ash 30 20  N Stewartia   monodelpha Orange  Bak Ste- wartia 30 20 Orange  peeling bark -  white flowers in  spring. N Taxus  brevifolia Pacific  Yew 40 25 Typically  occurs as  an understory tree 3- 5 m tall west of the  Cascades. Y Tilia  cordata 'De  Groot' De  Groot Littleleaf  Linden 30 20 Compct,  suckers less  than other Lindens.N Tilia cordata  'Chan-Chancelor Linden 35 20 Pyramidal.N Table V-12.3: Recommended Newly Planted Tree Species for Flow Control Credit (continued) 2024 Stormwater Management Manual for Western Washington Volume V -Chapter 12 -Page 1080 C. Correspondence N/A D. Site Inspection Form Construction Stormwater Site Inspection Form Page 1 Project Name Permit # Inspection Date Time Name of Certified Erosion Sediment Control Lead (CESCL) or qualified inspector if less than one acre Print Name: Approximate rainfall amount since the last inspection (in inches): Approximate rainfall amount in the last 24 hours (in inches): Current Weather Clear Cloudy Mist Rain Wind Fog A. Type of inspection: Weekly Post Storm Event Other B. Phase of Active Construction (check all that apply): Pre Construction/installation of erosion/sediment controls Clearing/Demo/Grading Infrastructure/storm/roads Concrete pours Vertical Construction/buildings Utilities Offsite improvements Site temporary stabilized Final stabilization C. Questions: 1. Were all areas of construction and discharge points inspected? Yes No 2. Did you observe the presence of suspended sediment, turbidity, discoloration, or oil sheen Yes No 3. Was a water quality sample taken during inspection? (refer to permit conditions S4 & S5) Yes No 4. Was there a turbid discharge 250 NTU or greater, or Transparency 6 cm or less?* Yes No 5. If yes to #4 was it reported to Ecology? Yes No 6. Is pH sampling required? pH range required is 6.5 to 8.5. Yes No If answering yes to a discharge, describe the event. Include when, where, and why it happened; what action was taken, and when. *If answering yes to # 4 record NTU/Transparency with continual sampling daily until turbidity is 25 NTU or less/ transparency is 33 cm or greater. Sampling Results: Date: Parameter Method (circle one) Result Other/Note NTU cm pH Turbidity tube, meter, laboratory pH Paper, kit, meter Construction Stormwater Site Inspection Form Page 2 D. Check the observed status of all items. Provide “Action Required “details and dates. Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 1 Clearing Limits Before beginning land disturbing activities are all clearing limits, natural resource areas (streams, wetlands, buffers, trees) protected with barriers or similar BMPs? (high visibility recommended) 2 Construction Access Construction access is stabilized with quarry spalls or equivalent BMP to prevent sediment from being tracked onto roads? Sediment tracked onto the road way was cleaned thoroughly at the end of the day or more frequent as necessary. 3 Control Flow Rates Are flow control measures installed to control stormwater volumes and velocity during construction and do they protect downstream properties and waterways from erosion? If permanent infiltration ponds are used for flow control during construction, are they protected from siltation? 4 Sediment Controls All perimeter sediment controls (e.g. silt fence, wattles, compost socks, berms, etc.) installed, and maintained in accordance with the Stormwater Pollution Prevention Plan (SWPPP). Sediment control BMPs (sediment ponds, traps, filters etc.) have been constructed and functional as the first step of grading. Stormwater runoff from disturbed areas is directed to sediment removal BMP. 5 Stabilize Soils Have exposed un-worked soils been stabilized with effective BMP to prevent erosion and sediment deposition? Construction Stormwater Site Inspection Form Page 3 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 5 Stabilize Soils Cont. Are stockpiles stabilized from erosion, protected with sediment trapping measures and located away from drain inlet, waterways, and drainage channels? Have soils been stabilized at the end of the shift, before a holiday or weekend if needed based on the weather forecast? 6 Protect Slopes Has stormwater and ground water been diverted away from slopes and disturbed areas with interceptor dikes, pipes and or swales? Is off-site storm water managed separately from stormwater generated on the site? Is excavated material placed on uphill side of trenches consistent with safety and space considerations? Have check dams been placed at regular intervals within constructed channels that are cut down a slope? 7 Drain Inlets Storm drain inlets made operable during construction are protected. Are existing storm drains within the influence of the project protected? 8 Stabilize Channel and Outlets Have all on-site conveyance channels been designed, constructed and stabilized to prevent erosion from expected peak flows? Is stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes and downstream conveyance systems? 9 Control Pollutants Are waste materials and demolition debris handled and disposed of to prevent contamination of stormwater? Has cover been provided for all chemicals, liquid products, petroleum products, and other material? Has secondary containment been provided capable of containing 110% of the volume? Were contaminated surfaces cleaned immediately after a spill incident? Were BMPs used to prevent contamination of stormwater by a pH modifying sources? Construction Stormwater Site Inspection Form Page 4 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 9 Cont. Wheel wash wastewater is handled and disposed of properly. 10 Control Dewatering Concrete washout in designated areas. No washout or excess concrete on the ground. Dewatering has been done to an approved source and in compliance with the SWPPP. Were there any clean non turbid dewatering discharges? 11 Maintain BMP Are all temporary and permanent erosion and sediment control BMPs maintained to perform as intended? 12 Manage the Project Has the project been phased to the maximum degree practicable? Has regular inspection, monitoring and maintenance been performed as required by the permit? Has the SWPPP been updated, implemented and records maintained? 13 Protect LID Is all Bioretention and Rain Garden Facilities protected from sedimentation with appropriate BMPs? Is the Bioretention and Rain Garden protected against over compaction of construction equipment and foot traffic to retain its infiltration capabilities? Permeable pavements are clean and free of sediment and sediment laden- water runoff. Muddy construction equipment has not been on the base material or pavement. Have soiled permeable pavements been cleaned of sediments and pass infiltration test as required by stormwater manual methodology? Heavy equipment has been kept off existing soils under LID facilities to retain infiltration rate. E. Check all areas that have been inspected. All in place BMPs All disturbed soils All concrete wash out area All material storage areas All discharge locations All equipment storage areas All construction entrances/exits Construction Stormwater Site Inspection Form Page 5 F. Elements checked “Action Required” (section D) describe corrective action to be taken. List the element number; be specific on location and work needed. Document, initial, and date when the corrective action has been completed and inspected. Element # Description and Location Action Required Completion Date Initials Attach additional page if needed Sign the following certification: “I certify that this report is true, accurate, and complete, to the best of my knowledge and belief” Inspected by: (print) (Signature) Date: Title/Qualification of Inspector: E. Construction Stormwater General Permit (CSWGP) Issuance Date: November 18, 2020 Effective Date: January 1, 2021 Expiration Date: December 31, 2025 CONSTRUCTION STORMWATER GENERAL PERMIT National Pollutant Discharge Elimination System (NPDES) and State Waste Discharge General Permit for Stormwater Discharges Associated with Construction Activity State of Washington Department of Ecology Olympia, Washington 98504 In compliance with the provisions of Chapter 90.48 Revised Code of Washington (State of Washington Water Pollution Control Act) and Title 33 United States Code, Section 1251 et seq. The Federal Water Pollution Control Act (The Clean Water Act) Until this permit expires, is modified, or revoked, Permittees that have properly obtained coverage under this general permit are authorized to discharge in accordance with the special and general conditions that follow. __________________________________ Vincent McGowan, P.E. Water Quality Program Manager Washington State Department of Ecology Construction Stormwater General Permit Page i TABLE OF CONTENTS LIST OF TABLES .................................................................................................................................. ii SUMMARY OF PERMIT REPORT SUBMITTALS ...................................................................................... 1 SPECIAL CONDITIONS ......................................................................................................................... 3 S1. Permit Coverage .............................................................................................................................. 3 S2. Application Requirements ............................................................................................................... 7 S3. Compliance with Standards ............................................................................................................. 9 S4. Monitoring Requirements, Benchmarks, and Reporting Triggers ................................................. 10 S5. Reporting and Recordkeeping Requirements ................................................................................ 17 S6. Permit Fees .................................................................................................................................... 20 S7. Solid and Liquid Waste Disposal .................................................................................................... 20 S8. Discharges to 303(D) or TMDL Waterbodies ................................................................................. 20 S9. Stormwater Pollution Prevention Plan .......................................................................................... 23 S10. Notice Of Termination ................................................................................................................... 32 GENERAL CONDITIONS ..................................................................................................................... 34 G1. Discharge Violations....................................................................................................................... 34 G2. Signatory Requirements ................................................................................................................ 34 G3. Right of Inspection and Entry ......................................................................................................... 35 G4. General Permit Modification and Revocation ............................................................................... 35 G5. Revocation of Coverage Under tPermit ......................................................................................... 35 G6. Reporting a Cause for Modification ............................................................................................... 36 G7. Compliance with Other Laws and Statutes .................................................................................... 36 G8. Duty to Reapply.............................................................................................................................. 36 G9. Removed Substance ....................................................................................................................... 36 G10. Duty to Provide Information .......................................................................................................... 36 G11. Other Requirements of 40 CFR ...................................................................................................... 37 G12. Additional Monitoring .................................................................................................................... 37 G13. Penalties for Violating Permit Conditions ...................................................................................... 37 G14. Upset .............................................................................................................................................. 37 G15. Property Rights .............................................................................................................................. 37 G16. Duty to Comply .............................................................................................................................. 37 G17. Toxic Pollutants .............................................................................................................................. 38 G18. Penalties for Tampering ................................................................................................................. 38 G19. Reporting Planned Changes ........................................................................................................... 38 G20. Reporting Other Information ......................................................................................................... 38 G21. Reporting Anticipated Non-Compliance ........................................................................................ 38 Construction Stormwater General Permit Page ii G22. Requests to Be Excluded From Coverage Under the Permit ......................................................... 39 G23. Appeals........................................................................................................................................... 39 G24. Severability..................................................................................................................................... 39 G25. Bypass Prohibited .......................................................................................................................... 39 APPENDIX A – DEFINITIONS .............................................................................................................. 42 APPENDIX B – ACRONYMS ................................................................................................................ 50 LIST OF TABLES Table 1 Summary of Required Submittals ................................................................................................ 1 Table 2 Summary of Required On-site Documentation ........................................................................... 2 Table 3 Summary of Primary Monitoring Requirements ....................................................................... 12 Table 4 Monitoring and Reporting Requirements ................................................................................. 14 Table 5 Turbidity, Fine Sediment & Phosphorus Sampling and Limits for 303(d)-Listed Waters ................................................................................................................ 22 Table 6 pH Sampling and Limits for 303(d)-Listed Waters ..................................................................... 22 Construction Stormwater General Permit Page 1 SUMMARY OF PERMIT REPORT SUBMITTALS Refer to the Special and General Conditions within this permit for additional submittal requirements. Appendix A provides a list of definitions. Appendix B provides a list of acronyms. Table 1 Summary of Required Submittals Permit Section Submittal Frequency First Submittal Date S5.A and S8 High Turbidity/Transparency Phone Reporting As Necessary Within 24 hours S5.B Discharge Monitoring Report Monthly* Within 15 days following the end of each month S5.F and S8 Noncompliance Notification – Telephone Notification As necessary Within 24 hours S5.F Noncompliance Notification – Written Report As necessary Within 5 Days of non-compliance S9.D Request for Chemical Treatment Form As necessary Written approval from Ecology is required prior to using chemical treatment (with the exception of dry ice, CO2 or food grade vinegar to adjust pH) G2 Notice of Change in Authorization As necessary G6 Permit Application for Substantive Changes to the Discharge As necessary G8 Application for Permit Renewal 1/permit cycle No later than 180 days before expiration S2.A Notice of Permit Transfer As necessary G19 Notice of Planned Changes As necessary G21 Reporting Anticipated Non-compliance As necessary NOTE: *Permittees must submit electronic Discharge Monitoring Reports (DMRs) to the Washington State Department of Ecology monthly, regardless of site discharge, for the full duration of permit coverage. Refer to Section S5.B of this General Permit for more specific information regarding DMRs. Construction Stormwater General Permit Page 2 Table 2 Summary of Required On-site Documentation Document Title Permit Conditions Permit Coverage Letter See Conditions S2, S5 Construction Stormwater General Permit (CSWGP) See Conditions S2, S5 Site Log Book See Conditions S4, S5 Stormwater Pollution Prevention Plan (SWPPP) See Conditions S5, S9 Site Map See Conditions S5, S9 Construction Stormwater General Permit Page 3 SPECIAL CONDITIONS S1. PERMIT COVERAGE A. Permit Area This Construction Stormwater General Permit (CSWGP) covers all areas of Washington State, except for federal operators and Indian Country as specified in Special Condition S1.E.3 and 4. B. Operators Required to Seek Coverage Under this General Permit 1. Operators of the following construction activities are required to seek coverage under this CSWGP: a. Clearing, grading and/or excavation that results in the disturbance of one or more acres (including off-site disturbance acreage related to construction-support activity as authorized in S1.C.2) and discharges stormwater to surface waters of the State; and clearing, grading and/or excavation on sites smaller than one acre that are part of a larger common plan of development or sale, if the common plan of development or sale will ultimately disturb one acre or more and discharge stormwater to surface waters of the State. i. This category includes forest practices (including, but not limited to, class IV conversions) that are part of a construction activity that will result in the disturbance of one or more acres, and discharge to surface waters of the State (that is, forest practices that prepare a site for construction activities); and b. Any size construction activity discharging stormwater to waters of the State that the Washington State Department of Ecology (Ecology): i. Determines to be a significant contributor of pollutants to waters of the State of Washington. ii. Reasonably expects to cause a violation of any water quality standard. 2. Operators of the following activities are not required to seek coverage under this CSWGP (unless specifically required under Special Condition S1.B.1.b, above): a. Construction activities that discharge all stormwater and non-stormwater to groundwater, sanitary sewer, or combined sewer, and have no point source discharge to either surface water or a storm sewer system that drains to surface waters of the State. b. Construction activities covered under an Erosivity Waiver (Special Condition S1.F). c. Routine maintenance that is performed to maintain the original line and grade, hydraulic capacity, or original purpose of a facility. C. Authorized Discharges 1. Stormwater Associated with Construction Activity. Subject to compliance with the terms and conditions of this permit, Permittees are authorized to discharge stormwater associated with construction activity to surface waters of the State or to a storm sewer system that drains to surface waters of the State. (Note that “surface waters of the Construction Stormwater General Permit Page 4 State” may exist on a construction site as well as off site; for example, a creek running through a site.) 2. Stormwater Associated with Construction Support Activity. This permit also authorizes stormwater discharge from support activities related to the permitted construction site (for example, an on-site portable rock crusher, off-site equipment staging yards, material storage areas, borrow areas, etc.) provided: a. The support activity relates directly to the permitted construction site that is required to have an NPDES permit; and b. The support activity is not a commercial operation serving multiple unrelated construction projects, and does not operate beyond the completion of the construction activity; and c. Appropriate controls and measures are identified in the Stormwater Pollution Prevention Plan (SWPPP) for the discharges from the support activity areas. 3. Non-Stormwater Discharges. The categories and sources of non-stormwater discharges identified below are authorized conditionally, provided the discharge is consistent with the terms and conditions of this permit: a. Discharges from fire-fighting activities. b. Fire hydrant system flushing. c. Potable water, including uncontaminated water line flushing. d. Hydrostatic test water. e. Uncontaminated air conditioning or compressor condensate. f. Uncontaminated groundwater or spring water. g. Uncontaminated excavation dewatering water (in accordance with S9.D.10). h. Uncontaminated discharges from foundation or footing drains. i. Uncontaminated or potable water used to control dust. Permittees must minimize the amount of dust control water used. j. Routine external building wash down that does not use detergents. k. Landscape irrigation water. The SWPPP must adequately address all authorized non-stormwater discharges, except for discharges from fire-fighting activities, and must comply with Special Condition S3. At a minimum, discharges from potable water (including water line flushing), fire hydrant system flushing, and pipeline hydrostatic test water must undergo the following: dechlorination to a concentration of 0.1 parts per million (ppm) or less, and pH adjustment to within 6.5 – 8.5 standard units (su), if necessary. D. Prohibited Discharges The following discharges to waters of the State, including groundwater, are prohibited: Construction Stormwater General Permit Page 5 1. Concrete wastewater 2. Wastewater from washout and clean-up of stucco, paint, form release oils, curing compounds and other construction materials. 3. Process wastewater as defined by 40 Code of Federal Regulations (CFR) 122.2 (See Appendix A of this permit). 4. Slurry materials and waste from shaft drilling, including process wastewater from shaft drilling for construction of building, road, and bridge foundations unless managed according to Special Condition S9.D.9.j. 5. Fuels, oils, or other pollutants used in vehicle and equipment operation and maintenance. 6. Soaps or solvents used in vehicle and equipment washing. 7. Wheel wash wastewater, unless managed according to Special Condition S9.D.9. 8. Discharges from dewatering activities, including discharges from dewatering of trenches and excavations, unless managed according to Special Condition S9.D.10. E. Limits on Coverage Ecology may require any discharger to apply for and obtain coverage under an individual permit or another more specific general permit. Such alternative coverage will be required when Ecology determines that this CSWGP does not provide adequate assurance that water quality will be protected, or there is a reasonable potential for the project to cause or contribute to a violation of water quality standards. The following stormwater discharges are not covered by this permit: 1. Post-construction stormwater discharges that originate from the site after completion of construction activities and the site has undergone final stabilization. 2. Non-point source silvicultural activities such as nursery operations, site preparation, reforestation and subsequent cultural treatment, thinning, prescribed burning, pest and fire control, harvesting operations, surface drainage, or road construction and maintenance, from which there is natural runoff as excluded in 40 CFR Subpart 122. 3. Stormwater from any federal operator. 4. Stormwater from facilities located on Indian Country as defined in 18 U.S.C.§1151, except portions of the Puyallup Reservation as noted below. Indian Country includes: a. All land within any Indian Reservation notwithstanding the issuance of any patent, and, including rights-of-way running through the reservation. This includes all federal, tribal, and Indian and non-Indian privately owned land within the reservation. b. All off-reservation Indian allotments, the Indian titles to which have not been extinguished, including rights-of-way running through the same. c. All off-reservation federal trust lands held for Native American Tribes. Construction Stormwater General Permit Page 6 Puyallup Exception: Following the Puyallup Tribes of Indians Land Settlement Act of 1989, 25 U.S.C. §1773; the permit does apply to land within the Puyallup Reservation except for discharges to surface water on land held in trust by the federal government. 5. Stormwater from any site covered under an existing NPDES individual permit in which stormwater management and/or treatment requirements are included for all stormwater discharges associated with construction activity. 6. Stormwater from a site where an applicable Total Maximum Daily Load (TMDL) requirement specifically precludes or prohibits discharges from construction activity. F. Erosivity Waiver Construction site operators may qualify for an Erosivity Waiver from the CSWGP if the following conditions are met: 1. The site will result in the disturbance of fewer than five (5) acres and the site is not a portion of a common plan of development or sale that will disturb five (5) acres or greater. 2. Calculation of Erosivity “R” Factor and Regional Timeframe: a. The project’s calculated rainfall erosivity factor (“R” Factor) must be less than five (5) during the period of construction activity, (See the CSWGP homepage http://www.ecy.wa.gov/programs/wq/stormwater/construction/index.html for a link to the EPA’s calculator and step by step instructions on computing the “R” Factor in the EPA Erosivity Waiver Fact Sheet). The period of construction activity starts when the land is first disturbed and ends with final stabilization. In addition: b. The entire period of construction activity must fall within the following timeframes: i. For sites west of the Cascades Crest: June 15 – September 15. ii. For sites east of the Cascades Crest, excluding the Central Basin: June 15 – October 15. iii. For sites east of the Cascades Crest, within the Central Basin: no timeframe restrictions apply. The Central Basin is defined as the portions of Eastern Washington with mean annual precipitation of less than 12 inches. For a map of the Central Basin (Average Annual Precipitation Region 2), refer to: http://www.ecy.wa.gov/programs/wq/stormwater/construction/resourcesguida nce.html. 3. Construction site operators must submit a complete Erosivity Waiver certification form at least one week before disturbing the land. Certification must include statements that the operator will: a. Comply with applicable local stormwater requirements; and b. Implement appropriate erosion and sediment control BMPs to prevent violations of water quality standards. 4. This waiver is not available for facilities declared significant contributors of pollutants as defined in Special Condition S1.B.1.b or for any size construction activity that could Construction Stormwater General Permit Page 7 reasonably expect to cause a violation of any water quality standard as defined in Special Condition S1.B.1.b.ii. 5. This waiver does not apply to construction activities which include non-stormwater discharges listed in Special Condition S1.C.3. 6. If construction activity extends beyond the certified waiver period for any reason, the operator must either: a. Recalculate the rainfall erosivity “R” factor using the original start date and a new projected ending date and, if the “R” factor is still under 5 and the entire project falls within the applicable regional timeframe in Special Condition S1.F.2.b, complete and submit an amended waiver certification form before the original waiver expires; or b. Submit a complete permit application to Ecology in accordance with Special Condition S2.A and B before the end of the certified waiver period. S2. APPLICATION REQUIREMENTS A. Permit Application Forms 1. Notice of Intent Form a. Operators of new or previously unpermitted construction activities must submit a complete and accurate permit application (Notice of Intent, or NOI) to Ecology. b. Operators must apply using the electronic application form (NOI) available on Ecology’s website (http://ecy.wa.gov/programs/wq/stormwater/construction/index.html). Permittees unable to submit electronically (for example, those who do not have an internet connection) must contact Ecology to request a waiver and obtain instructions on how to obtain a paper NOI. Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 c. The operator must submit the NOI at least 60 days before discharging stormwater from construction activities and must submit it prior to the date of the first public notice (See Special Condition S2.B, below, for details). The 30-day public comment period begins on the publication date of the second public notice. Unless Ecology responds to the complete application in writing, coverage under the general permit will automatically commence on the 31st day following receipt by Ecology of a completed NOI, or the issuance date of this permit, whichever is later; unless Ecology specifies a later date in writing as required by WAC173-226-200(2). See S8.B for Limits on Coverage for New Discharges to TMDL or 303(d)-Listed Waters. d. If an applicant intends to use a Best Management Practice (BMP) selected on the basis of Special Condition S9.C.4 (“demonstrably equivalent” BMPs), the applicant must notify Ecology of its selection as part of the NOI. In the event the applicant selects BMPs after submission of the NOI, the applicant must provide notice of the Construction Stormwater General Permit Page 8 selection of an equivalent BMP to Ecology at least 60 days before intended use of the equivalent BMP. e. Applicants must notify Ecology if they are aware of contaminated soils and/or groundwater associated with the construction activity. Provide detailed information with the NOI (as known and readily available) on the nature and extent of the contamination (concentrations, locations, and depth), as well as pollution prevention and/or treatment BMPs proposed to control the discharge of soil and/or groundwater contaminants in stormwater. Examples of such detail may include, but are not limited to: i. List or table of all known contaminants with laboratory test results showing concentration and depth, ii. Map with sample locations, iii. Related portions of the Stormwater Pollution Prevention Plan (SWPPP) that address the management of contaminated and potentially contaminated construction stormwater and dewatering water, iv. Dewatering plan and/or dewatering contingency plan. 2. Transfer of Coverage Form The Permittee can transfer current coverage under this permit to one or more new operators, including operators of sites within a Common Plan of Development, provided: i. The Permittee submits a complete Transfer of Coverage Form to Ecology, signed by the current and new discharger and containing a specific date for transfer of permit responsibility, coverage and liability (including any Administrative Orders associated with the permit); and ii. Ecology does not notify the current discharger and new discharger of intent to revoke coverage under the general permit. If this notice is not given, the transfer is effective on the date specified in the written agreement. When a current discharger (Permittee) transfers a portion of a permitted site, the current discharger must also indicate the remaining permitted acreage after the transfer. Transfers do not require public notice. 3. Modification of Coverage Form Permittees must notify Ecology regarding any changes to the information provided on the NOI by submitting an Update/Modification of Permit Coverage form in accordance with General Conditions G6 and G19. Examples of such changes include, but are not limited to: i. Changes to the Permittee’s mailing address, ii. Changes to the on-site contact person information, and iii. Changes to the area/acreage affected by construction activity. Construction Stormwater General Permit Page 9 B. Public Notice For new or previously unpermitted construction activities, the applicant must publish a public notice at least one time each week for two consecutive weeks, at least 7 days apart, in a newspaper with general circulation in the county where the construction is to take place. The notice must be run after the NOI has been submitted and must contain: 1. A statement that “The applicant is seeking coverage under the Washington State Department of Ecology’s Construction Stormwater NPDES and State Waste Discharge General Permit.” 2. The name, address, and location of the construction site. 3. The name and address of the applicant. 4. The type of construction activity that will result in a discharge (for example, residential construction, commercial construction, etc.), and the total number of acres to be disturbed over the lifetime of the project. 5. The name of the receiving water(s) (that is, the surface water(s) to which the site will discharge), or, if the discharge is through a storm sewer system, the name of the operator of the system and the receiving water(s) the system discharges to. 6. The statement: Any persons desiring to present their views to the Washington State Department of Ecology regarding this application, or interested in Ecology’s action on this application, may notify Ecology in writing no later than 30 days of the last date of publication of this notice. Ecology reviews public comments and considers whether discharges from this project would cause a measurable change in receiving water quality, and, if so, whether the project is necessary and in the overriding public interest according to Tier II antidegradation requirements under WAC 173-201A-320. Comments can be submitted to: Department of Ecology, PO Box 47696, Olympia, Washington 98504-7696 Attn: Water Quality Program, Construction Stormwater. S3. COMPLIANCE WITH STANDARDS A. Discharges must not cause or contribute to a violation of surface water quality standards (Chapter 173-201A WAC), groundwater quality standards (Chapter 173-200 WAC), sediment management standards (Chapter 173-204 WAC), and human health-based criteria in the Federal water quality criteria applicable to Washington. (40 CFR Part 131.45) Discharges that are not in compliance with these standards are prohibited. B. Prior to the discharge of stormwater and non-stormwater to waters of the State, the Permittee must apply All Known, Available, and Reasonable methods of prevention, control, and Treatment (AKART). This includes the preparation and implementation of an adequate SWPPP, with all appropriate BMPs installed and maintained in accordance with the SWPPP and the terms and conditions of this permit. C. Ecology presumes that a Permittee complies with water quality standards unless discharge monitoring data or other site-specific information demonstrates that a discharge causes or contributes to a violation of water quality standards, when the Permittee complies with the following conditions. The Permittee must fully: Construction Stormwater General Permit Page 10 1. Comply with all permit conditions, including; planning, sampling, monitoring, reporting, and recordkeeping conditions. 2. Implement stormwater BMPs contained in stormwater management manuals published or approved by Ecology, or BMPs that are demonstrably equivalent to BMPs contained in stormwater management manuals published or approved by Ecology, including the proper selection, implementation, and maintenance of all applicable and appropriate BMPs for on-site pollution control. (For purposes of this section, the stormwater manuals listed in Appendix 10 of the Phase I Municipal Stormwater Permit are approved by Ecology.) D. Where construction sites also discharge to groundwater, the groundwater discharges must also meet the terms and conditions of this CSWGP. Permittees who discharge to groundwater through an injection well must also comply with any applicable requirements of the Underground Injection Control (UIC) regulations, Chapter 173-218 WAC. S4. MONITORING REQUIREMENTS, BENCHMARKS, AND REPORTING TRIGGERS A. Site Log Book The Permittee must maintain a site log book that contains a record of the implementation of the SWPPP and other permit requirements, including the installation and maintenance of BMPs, site inspections, and stormwater monitoring. B. Site Inspections Construction sites one (1) acre or larger that discharge stormwater to surface waters of the State must have site inspections conducted by a Certified Erosion and Sediment Control Lead (CESCL). Sites less than one (1) acre may have a person without CESCL certification conduct inspections. (See Special Conditions S4.B.3 and B.4, below, for detailed requirements of the Permittee’s CESCL.) Site inspections must include all areas disturbed by construction activities, all BMPs, and all stormwater discharge points under the Permittee’s operational control. 1. The Permittee must have staff knowledgeable in the principles and practices of erosion and sediment control. The CESCL (sites one acre or more) or inspector (sites less than one acre) must have the skills to assess the: a. Site conditions and construction activities that could impact the quality of stormwater; and b. Effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. The SWPPP must identify the CESCL or inspector, who must be present on site or on-call at all times. The CESCL (sites one (1) acre or more) must obtain this certification through an approved erosion and sediment control training program that meets the minimum training standards established by Ecology. (See BMP C160 in the manual, referred to in Special Condition S9.C.1 and 2.) 2. The CESCL or inspector must examine stormwater visually for the presence of suspended sediment, turbidity, discoloration, and oil sheen. BMP effectiveness must be evaluated to Construction Stormwater General Permit Page 11 determine if it is necessary to install, maintain, or repair BMPs to improve the quality of stormwater discharges. Based on the results of the inspection, the Permittee must correct the problems identified, by: a. Reviewing the SWPPP for compliance with Special Condition S9 and making appropriate revisions within 7 days of the inspection. b. Immediately beginning the process of fully implementing and maintaining appropriate source control and/or treatment BMPs, within 10 days of the inspection. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when an extension is requested by a Permittee within the initial 10-day response period. c. Documenting BMP implementation and maintenance in the site log book. 3. The CESCL or inspector must inspect all areas disturbed by construction activities, all BMPs, and all stormwater discharge points at least once every calendar week and within 24 hours of any discharge from the site. (For purposes of this condition, individual discharge events that last more than one (1) day do not require daily inspections. For example, if a stormwater pond discharges continuously over the course of a week, only one (1) inspection is required that week.) Inspection frequency may be reduced to once every calendar month for inactive sites that are temporarily stabilized. 4. The Permittee must summarize the results of each inspection in an inspection report or checklist and enter the report/checklist into, or attach it to, the site log book. At a minimum, each inspection report or checklist must include: a. Inspection date and time. b. Weather information. c. The general conditions during inspection. d. The approximate amount of precipitation since the last inspection. e. The approximate amount of precipitation within the last 24 hours. f. A summary or list of all implemented BMPs, including observations of all erosion/sediment control structures or practices. g. A description of: i. BMPs inspected (including location). ii. BMPs that need maintenance and why. iii. BMPs that failed to operate as designed or intended, and iv. Where additional or different BMPs are needed, and why. h. A description of stormwater discharged from the site. The Permittee must note the presence of suspended sediment, turbidity, discoloration, and oil sheen, as applicable. Construction Stormwater General Permit Page 12 i. Any water quality monitoring performed during inspection. j. General comments and notes, including a brief description of any BMP repairs, maintenance, or installations made following the inspection. k. An implementation schedule for the remedial actions that the Permittee plans to take if the site inspection indicates that the site is out of compliance. The remedial actions taken must meet the requirements of the SWPPP and the permit. l. A summary report of the inspection. m. The name, title, and signature of the person conducting the site inspection, a phone number or other reliable method to reach this person, and the following statement: I certify that this report is true, accurate, and complete to the best of my knowledge and belief. Table 3 Summary of Primary Monitoring Requirements Size of Soil Disturbance 1 Weekly Site Inspections Weekly Sampling w/ Turbidity Meter Weekly Sampling w/ Transparency Tube Weekly pH Sampling 2 CESCL Required for Inspections? Sites that disturb less than 1 acre, but are part of a larger Common Plan of Development Required Not Required Not Required Not Required No Sites that disturb 1 acre or more, but fewer than 5 acres Required Sampling Required – either method 3 Required Yes Sites that disturb 5 acres or more Required Required Not Required 4 Required Yes 1 Soil disturbance is calculated by adding together all areas that will be affected by construction activity. Construction activity means clearing, grading, excavation, and any other activity that disturbs the surface of the land, including ingress/egress from the site. 2 If construction activity results in the disturbance of 1 acre or more, and involves significant concrete work (1,000 cubic yards of concrete or recycled concrete placed or poured over the life of a project) or the use of engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD], or fly ash), and stormwater from the affected area drains to surface waters of the State or to a storm sewer stormwater collection system that drains to other surface waters of the State, the Permittee must conduct pH sampling in accordance with Special Condition S4.D. 3 Sites with one or more acres, but fewer than 5 acres of soil disturbance, must conduct turbidity or transparency sampling in accordance with Special Condition S4.C.4.a or b. 4 Sites equal to or greater than 5 acres of soil disturbance must conduct turbidity sampling using a turbidity meter in accordance with Special Condition S4.C.4.a. Construction Stormwater General Permit Page 13 C. Turbidity/Transparency Sampling Requirements 1. Sampling Methods a. If construction activity involves the disturbance of five (5) acres or more, the Permittee must conduct turbidity sampling per Special Condition S4.C.4.a, below. b. If construction activity involves one (1) acre or more but fewer than five (5) acres of soil disturbance, the Permittee must conduct either transparency sampling or turbidity sampling per Special Condition S4.C.4.a or b, below. 2. Sampling Frequency a. The Permittee must sample all discharge points at least once every calendar week when stormwater (or authorized non-stormwater) discharges from the site or enters any on-site surface waters of the state (for example, a creek running through a site); sampling is not required on sites that disturb less than an acre. b. Samples must be representative of the flow and characteristics of the discharge. c. Sampling is not required when there is no discharge during a calendar week. d. Sampling is not required outside of normal working hours or during unsafe conditions. e. If the Permittee is unable to sample during a monitoring period, the Permittee must include a brief explanation in the monthly Discharge Monitoring Report (DMR). f. Sampling is not required before construction activity begins. g. The Permittee may reduce the sampling frequency for temporarily stabilized, inactive sites to once every calendar month. 3. Sampling Locations a. Sampling is required at all points where stormwater associated with construction activity (or authorized non-stormwater) is discharged off site, including where it enters any on-site surface waters of the state (for example, a creek running through a site). b. The Permittee may discontinue sampling at discharge points that drain areas of the project that are fully stabilized to prevent erosion. c. The Permittee must identify all sampling point(s) in the SWPPP and on the site map and clearly mark these points in the field with a flag, tape, stake or other visible marker. d. Sampling is not required for discharge that is sent directly to sanitary or combined sewer systems. e. The Permittee may discontinue sampling at discharge points in areas of the project where the Permittee no longer has operational control of the construction activity. Construction Stormwater General Permit Page 14 4. Sampling and Analysis Methods a. The Permittee performs turbidity analysis with a calibrated turbidity meter (turbidimeter) either on site or at an accredited lab. The Permittee must record the results in the site log book in nephelometric turbidity units (NTUs). b. The Permittee performs transparency analysis on site with a 1¾ inch diameter, 60 centimeter (cm)-long transparency tube. The Permittee will record the results in the site log book in centimeters (cm). Table 4 Monitoring and Reporting Requirements Parameter Unit Analytical Method Sampling Frequency Benchmark Value Turbidity NTU SM2130 Weekly, if discharging 25 NTUs Transparency Cm Manufacturer instructions, or Ecology guidance Weekly, if discharging 33 cm 5. Turbidity/Transparency Benchmark Values and Reporting Triggers The benchmark value for turbidity is 25 NTUs. The benchmark value for transparency is 33 centimeters (cm). Note: Benchmark values do not apply to discharges to segments of water bodies on Washington State’s 303(d) list (Category 5) for turbidity, fine sediment, or phosphorus; these discharges are subject to a numeric effluent limit for turbidity. Refer to Special Condition S8 for more information and follow S5.F – Noncompliance Notification for reporting requirements applicable to discharges which exceed the numeric effluent limit for turbidity. a. Turbidity 26 – 249 NTUs, or Transparency 32 – 7 cm: If the discharge turbidity is 26 to 249 NTUs; or if discharge transparency is 32 to 7 cm, the Permittee must: i. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs, and no later than 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. ii. Review the SWPPP for compliance with Special Condition S9 and make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. iii. Document BMP implementation and maintenance in the site log book. b. Turbidity 250 NTUs or greater, or Transparency 6 cm or less: If a discharge point’s turbidity is 250 NTUs or greater, or if discharge transparency is less than or equal to 6 cm, the Permittee must complete the reporting and adaptive Construction Stormwater General Permit Page 15 management process described below. For discharges which are subject to a numeric effluent limit for turbidity, see S5.F – Noncompliance Notification. i. Within 24 hours, telephone or submit an electronic report to the applicable Ecology Region’s Environmental Report Tracking System (ERTS) number (or through Ecology’s Water Quality Permitting Portal [WQWebPortal] – Permit Submittals when the form is available), in accordance with Special Condition S5.A. • Central Region (Okanogan, Chelan, Douglas, Kittitas, Yakima, Klickitat, Benton): (509) 575-2490 • Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400 • Northwest Region (Kitsap, Snohomish, Island, King, San Juan, Skagit, Whatcom): (425) 649-7000 • Southwest Region (Grays Harbor, Lewis, Mason, Thurston, Pierce, Clark, Cowlitz, Skamania, Wahkiakum, Clallam, Jefferson, Pacific): (360) 407-6300 These numbers and a link to the ERTS reporting page are also listed at the following website: http://www.ecy.wa.gov/programs/wq/stormwater/construction/index.html. ii. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible, addressing the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. iii. Sample discharges daily until: a) Turbidity is 25 NTUs (or lower); or b) Transparency is 33 cm (or greater); or c) The Permittee has demonstrated compliance with the water quality standard for turbidity: 1) No more than 5 NTUs over background turbidity, if background is less than 50 NTUs, or 2) No more than 10% over background turbidity, if background is 50 NTUs or greater; or *Note: background turbidity in the receiving water must be measured immediately upstream (upgradient) or outside of the area of influence of the discharge. d) The discharge stops or is eliminated. iv. Review the SWPPP for compliance with Special Condition S9 and make appropriate revisions within seven (7) days of the date the discharge exceeded the benchmark. Construction Stormwater General Permit Page 16 v. Document BMP implementation and maintenance in the site log book. Compliance with these requirements does not relieve the Permittee from responsibility to maintain continuous compliance with permit benchmarks. D. pH Sampling Requirements – Significant Concrete Work or Engineered Soils If construction activity results in the disturbance of 1 acre or more, and involves significant concrete work (significant concrete work means greater than 1000 cubic yards placed or poured concrete or recycled concrete used over the life of a project) or the use of engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD], or fly ash), and stormwater from the affected area drains to surface waters of the State or to a storm sewer system that drains to surface waters of the State, the Permittee must conduct pH sampling as set forth below. Note: In addition, discharges to segments of water bodies on Washington State’s 303(d) list (Category 5) for high pH are subject to a numeric effluent limit for pH; refer to Special Condition S8. 1. The Permittee must perform pH analysis on site with a calibrated pH meter, pH test kit, or wide range pH indicator paper. The Permittee must record pH sampling results in the site log book. 2. During the applicable pH monitoring period defined below, the Permittee must obtain a representative sample of stormwater and conduct pH analysis at least once per week. a. For sites with significant concrete work, the Permittee must begin the pH sampling period when the concrete is first placed or poured and exposed to precipitation, and continue weekly throughout and after the concrete placement, pour and curing period, until stormwater pH is in the range of 6.5 to 8.5 (su). b. For sites with recycled concrete where monitoring is required, the Permittee must begin the weekly pH sampling period when the recycled concrete is first exposed to precipitation and must continue until the recycled concrete is fully stabilized with the stormwater pH in the range of 6.5 to 8.5 (su). c. For sites with engineered soils, the Permittee must begin the pH sampling period when the soil amendments are first exposed to precipitation and must continue until the area of engineered soils is fully stabilized. 3. The Permittee must sample pH in the sediment trap/pond(s) or other locations that receive stormwater runoff from the area of significant concrete work or engineered soils before the stormwater discharges to surface waters. 4. The benchmark value for pH is 8.5 standard units. Anytime sampling indicates that pH is 8.5 or greater, the Permittee must either: a. Prevent the high pH water (8.5 or above) from entering storm sewer systems or surface waters of the state; or b. If necessary, adjust or neutralize the high pH water until it is in the range of pH 6.5 to 8.5 (su) using an appropriate treatment BMP such as carbon dioxide (CO2) sparging, dry ice or food grade vinegar. The Permittee must obtain written approval from Ecology before using any form of chemical treatment other than CO2 sparging, dry ice or food grade vinegar. Construction Stormwater General Permit Page 17 S5. REPORTING AND RECORDKEEPING REQUIREMENTS A. High Turbidity Reporting Anytime sampling performed in accordance with Special Condition S4.C indicates turbidity has reached the 250 NTUs or more (or transparency less than or equal to 6 cm), high turbidity reporting level, the Permittee must notify Ecology within 24 hours of analysis either by calling the applicable Ecology Region’s Environmental Report Tracking System (ERTS) number by phone or by submitting an electronic ERTS report (through Ecology’s Water Quality Permitting Portal (WQWebPortal) – Permit Submittals when the form is available). See the CSWGP website for links to ERTS and the WQWebPortal. (http://www.ecy.wa.gov/programs/wq/stormwater/ construction/index.html) Also, see phone numbers in Special Condition S4.C.5.b.i. B. Discharge Monitoring Reports (DMRs) Permittees required to conduct water quality sampling in accordance with Special Conditions S4.C (Turbidity/Transparency), S4.D (pH), S8 (303[d]/TMDL sampling), and/or G12 (Additional Sampling) must submit the results to Ecology. Permittees must submit monitoring data using Ecology's WQWebDMR web application accessed through Ecology’s Water Quality Permitting Portal. Permittees unable to submit electronically (for example, those who do not have an internet connection) must contact Ecology to request a waiver and obtain instructions on how to obtain a paper copy DMR at: Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, WA 98504-7696 Permittees who obtain a waiver not to use WQWebDMR must use the forms provided to them by Ecology; submittals must be mailed to the address above. Permittees must submit DMR forms to be received by Ecology within 15 days following the end of each month. If there was no discharge during a given monitoring period, all Permittees must submit a DMR as required with “no discharge” entered in place of the monitoring results. DMRs are required for the full duration of permit coverage (from the first full month following the effective date of permit coverage up until Ecology has approved termination of the coverage). For more information, contact Ecology staff using information provided at the following website: www.ecy.wa.gov/programs/wq/permits/paris/contacts.html. C. Records Retention The Permittee must retain records of all monitoring information (site log book, sampling results, inspection reports/checklists, etc.), Stormwater Pollution Prevention Plan, copy of the permit coverage letter (including Transfer of Coverage documentation) and any other documentation of compliance with permit requirements for the entire life of the construction project and for a minimum of five (5) years following the termination of permit coverage. Such information must include all calibration and maintenance records, and records of all data used to complete the application for this permit. This period of retention must be extended during Construction Stormwater General Permit Page 18 the course of any unresolved litigation regarding the discharge of pollutants by the Permittee or when requested by Ecology. D. Recording Results For each measurement or sample taken, the Permittee must record the following information: 1. Date, place, method, and time of sampling or measurement. 2. The first and last name of the individual who performed the sampling or measurement. 3. The date(s) the analyses were performed. 4. The first and last name of the individual who performed the analyses. 5. The analytical techniques or methods used. 6. The results of all analyses. E. Additional Monitoring by the Permittee If the Permittee samples or monitors any pollutant more frequently than required by this permit using test procedures specified by Special Condition S4 of this permit, the sampling results for this monitoring must be included in the calculation and reporting of the data submitted in the Permittee’s DMR. F. Noncompliance Notification In the event the Permittee is unable to comply with any part of the terms and conditions of this permit, and the resulting noncompliance may cause a threat to human health or the environment (such as but not limited to spills or fuels or other materials, catastrophic pond or slope failure, and discharges that violate water quality standards), or exceed numeric effluent limitations (see S8 – Discharges to 303(d) or TMDL Waterbodies), the Permittee must, upon becoming aware of the circumstance: 1. Notify Ecology within 24 hours of the failure to comply by calling the applicable Regional office ERTS phone number (refer to Special Condition S4.C.5.b.i, or go to https://ecology.wa.gov/About-us/Get-involved/Report-an-environmental-issue to find contact information for the regional offices.) 2. Immediately take action to prevent the discharge/pollution, or otherwise stop or correct the noncompliance, and, if applicable, repeat sampling and analysis of any noncompliance immediately and submit the results to Ecology within five (5) days of becoming aware of the violation (See S5.F.3, below, for details on submitting results in a report). 3. Submit a detailed written report to Ecology within five (5) days of the time the Permittee becomes aware of the circumstances, unless requested earlier by Ecology. The report must be submitted using Ecology’s Water Quality Permitting Portal (WQWebPortal) – Permit Submittals, unless a waiver from electronic reporting has been granted according to S5.B. The report must contain a description of the noncompliance, including exact dates and times, and if the noncompliance has not been corrected, the anticipated time it is expected to continue; and the steps taken or planned to reduce, eliminate, and prevent reoccurrence of the noncompliance. Construction Stormwater General Permit Page 19 The Permittee must report any unanticipated bypass and/or upset that exceeds any effluent limit in the permit in accordance with the 24-hour reporting requirement contained in 40 C.F.R. 122.41(l)(6). Compliance with these requirements does not relieve the Permittee from responsibility to maintain continuous compliance with the terms and conditions of this permit or the resulting liability for failure to comply. Upon request of the Permittee, Ecology may waive the requirement for a written report on a case-by-case basis, if the immediate notification is received by Ecology within 24 hours. G. Access to Plans and Records 1. The Permittee must retain the following permit documentation (plans and records) on site, or within reasonable access to the site, for use by the operator or for on-site review by Ecology or the local jurisdiction: a. General Permit b. Permit Coverage Letter c. Stormwater Pollution Prevention Plan (SWPPP) d. Site Log Book e. Erosivity Waiver (if applicable) 2. The Permittee must address written requests for plans and records listed above (Special Condition S5.G.1) as follows: a. The Permittee must provide a copy of plans and records to Ecology within 14 days of receipt of a written request from Ecology. b. The Permittee must provide a copy of plans and records to the public when requested in writing. Upon receiving a written request from the public for the Permittee’s plans and records, the Permittee must either: i. Provide a copy of the plans and records to the requester within 14 days of a receipt of the written request; or ii. Notify the requester within 10 days of receipt of the written request of the location and times within normal business hours when the plans and records may be viewed; and provide access to the plans and records within 14 days of receipt of the written request; or Within 14 days of receipt of the written request, the Permittee may submit a copy of the plans and records to Ecology for viewing and/or copying by the requester at an Ecology office, or a mutually agreed location. If plans and records are viewed and/or copied at a location other than at an Ecology office, the Permittee will provide reasonable access to copying services for which a reasonable fee may be charged. The Permittee must notify the requester within 10 days of receipt of the request where the plans and records may be viewed and/or copied. Construction Stormwater General Permit Page 20 S6. PERMIT FEES The Permittee must pay permit fees assessed by Ecology. Fees for stormwater discharges covered under this permit are established by Chapter 173-224 WAC. Ecology continues to assess permit fees until the permit is terminated in accordance with Special Condition S10 or revoked in accordance with General Condition G5. S7. SOLID AND LIQUID WASTE DISPOSAL The Permittee must handle and dispose of solid and liquid wastes generated by construction activity, such as demolition debris, construction materials, contaminated materials, and waste materials from maintenance activities, including liquids and solids from cleaning catch basins and other stormwater facilities, in accordance with: A. Special Condition S3, Compliance with Standards. B. WAC 173-216-110. C. Other applicable regulations. S8. DISCHARGES TO 303(d) OR TMDL WATERBODIES A. Sampling and Numeric Effluent Limits For Certain Discharges to 303(d)-Listed Water Bodies 1. Permittees who discharge to segments of water bodies listed as impaired by the State of Washington under Section 303(d) of the Clean Water Act for turbidity, fine sediment, high pH, or phosphorus, must conduct water quality sampling according to the requirements of this section, and Special Conditions S4.C.2.b-f and S4.C.3.b-d, and must comply with the applicable numeric effluent limitations in S8.C and S8.D. 2. All references and requirements associated with Section 303(d) of the Clean Water Act mean the most current listing by Ecology of impaired waters (Category 5) that exists on January 1, 2021, or the date when the operator’s complete permit application is received by Ecology, whichever is later. B. Limits on Coverage for New Discharges to TMDL or 303(d)-Listed Waters Construction sites that discharge to a TMDL or 303(d)-listed waterbody are not eligible for coverage under this permit unless the operator: Construction Stormwater General Permit Page 21 1. Prevents exposing stormwater to pollutants for which the waterbody is impaired, and retains documentation in the SWPPP that details procedures taken to prevent exposure on site; or 2. Documents that the pollutants for which the waterbody is impaired are not present at the site, and retains documentation of this finding within the SWPPP; or 3. Provides Ecology with data indicating the discharge is not expected to cause or contribute to an exceedance of a water quality standard, and retains such data on site with the SWPPP. The operator must provide data and other technical information to Ecology that sufficiently demonstrate: a. For discharges to waters without an EPA-approved or -established TMDL, that the discharge of the pollutant for which the water is impaired will meet in-stream water quality criteria at the point of discharge to the waterbody; or b. For discharges to waters with an EPA-approved or -established TMDL, that there is sufficient remaining wasteload allocation in the TMDL to allow construction stormwater discharge and that existing dischargers to the waterbody are subject to compliance schedules designed to bring the waterbody into attainment with water quality standards. Operators of construction sites are eligible for coverage under this permit only after Ecology makes an affirmative determination that the discharge will not cause or contribute to the existing impairment or exceed the TMDL. C. Sampling and Numeric Effluent Limits for Discharges to Water Bodies on the 303(d) List for Turbidity, Fine Sediment, or Phosphorus 1. Permittees who discharge to segments of water bodies on the 303(d) list (Category 5) for turbidity, fine sediment, or phosphorus must conduct turbidity sampling in accordance with Special Condition S4.C.2 and comply with either of the numeric effluent limits noted in Table 5 below. 2. As an alternative to the 25 NTUs effluent limit noted in Table 5 below (applied at the point where stormwater [or authorized non-stormwater] is discharged off-site), Permittees may choose to comply with the surface water quality standard for turbidity. The standard is: no more than 5 NTUs over background turbidity when the background turbidity is 50 NTUs or less, or no more than a 10% increase in turbidity when the background turbidity is more than 50 NTUs. In order to use the water quality standard requirement, the sampling must take place at the following locations: a. Background turbidity in the 303(d)-listed receiving water immediately upstream (upgradient) or outside the area of influence of the discharge. b. Turbidity at the point of discharge into the 303(d)-listed receiving water, inside the area of influence of the discharge. 3. Discharges that exceed the numeric effluent limit for turbidity constitute a violation of this permit. 4. Permittees whose discharges exceed the numeric effluent limit must sample discharges daily until the violation is corrected and comply with the non-compliance notification requirements in Special Condition S5.F. Construction Stormwater General Permit Page 22 Table 5 Turbidity, Fine Sediment & Phosphorus Sampling and Limits for 303(d)-Listed Waters Parameter identified in 303(d) listing Parameter Sampled Unit Analytical Method Sampling Frequency Numeric Effluent Limit1 • Turbidity • Fine Sediment • Phosphorus Turbidity NTU SM2130 Weekly, if discharging 25 NTUs, at the point where stormwater is discharged from the site; OR In compliance with the surface water quality standard for turbidity (S8.C.2.a) 1 Permittees subject to a numeric effluent limit for turbidity may, at their discretion, choose either numeric effluent limitation based on site-specific considerations including, but not limited to, safety, access and convenience. D. Discharges to Water Bodies on the 303(d) List for High pH 1. Permittees who discharge to segments of water bodies on the 303(d) list (Category 5) for high pH must conduct pH sampling in accordance with the table below, and comply with the numeric effluent limit of pH 6.5 to 8.5 su (Table 6). Table 6 pH Sampling and Limits for 303(d)-Listed Waters Parameter identified in 303(d) listing Parameter Sampled/Units Analytical Method Sampling Frequency Numeric Effluent Limit High pH pH /Standard Units pH meter Weekly, if discharging In the range of 6.5 – 8.5 su 2. At the Permittee’s discretion, compliance with the limit shall be assessed at one of the following locations: a. Directly in the 303(d)-listed waterbody segment, inside the immediate area of influence of the discharge; or b. Alternatively, the Permittee may measure pH at the point where the discharge leaves the construction site, rather than in the receiving water. 3. Discharges that exceed the numeric effluent limit for pH (outside the range of 6.5 – 8.5 su) constitute a violation of this permit. 4. Permittees whose discharges exceed the numeric effluent limit must sample discharges daily until the violation is corrected and comply with the non-compliance notification requirements in Special Condition S5.F. E. Sampling and Limits for Sites Discharging to Waters Covered by a TMDL or another Pollution Control Plan Construction Stormwater General Permit Page 23 1. Discharges to a waterbody that is subject to a Total Maximum Daily Load (TMDL) for turbidity, fine sediment, high pH, or phosphorus must be consistent with the TMDL. Refer to http://www.ecy.wa.gov/programs/wq/tmdl/TMDLsbyWria/TMDLbyWria.html for more information on TMDLs. a. Where an applicable TMDL sets specific waste load allocations or requirements for discharges covered by this permit, discharges must be consistent with any specific waste load allocations or requirements established by the applicable TMDL. i. The Permittee must sample discharges weekly, unless otherwise specified by the TMDL, to evaluate compliance with the specific waste load allocations or requirements. ii. Analytical methods used to meet the monitoring requirements must conform to the latest revision of the Guidelines Establishing Test Procedures for the Analysis of Pollutants contained in 40 CFR Part 136. iii. Turbidity and pH methods need not be accredited or registered unless conducted at a laboratory which must otherwise be accredited or registered. b. Where an applicable TMDL has established a general waste load allocation for construction stormwater discharges, but has not identified specific requirements, compliance with Special Conditions S4 (Monitoring) and S9 (SWPPPs) will constitute compliance with the approved TMDL. c. Where an applicable TMDL has not specified a waste load allocation for construction stormwater discharges, but has not excluded these discharges, compliance with Special Conditions S4 (Monitoring) and S9 (SWPPPs) will constitute compliance with the approved TMDL. d. Where an applicable TMDL specifically precludes or prohibits discharges from construction activity, the operator is not eligible for coverage under this permit. S9. STORMWATER POLLUTION PREVENTION PLAN The Permittee must prepare and properly implement an adequate Stormwater Pollution Prevention Plan (SWPPP) for construction activity in accordance with the requirements of this permit beginning with initial soil disturbance and until final stabilization. A. The Permittee’s SWPPP must meet the following objectives: 1. To identify best management practices (BMPs) which prevent erosion and sedimentation, and to reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. To prevent violations of surface water quality, groundwater quality, or sediment management standards. 3. To control peak volumetric flow rates and velocities of stormwater discharges. Construction Stormwater General Permit Page 24 B. General Requirements 1. The SWPPP must include a narrative and drawings. All BMPs must be clearly referenced in the narrative and marked on the drawings. The SWPPP narrative must include documentation to explain and justify the pollution prevention decisions made for the project. Documentation must include: a. Information about existing site conditions (topography, drainage, soils, vegetation, etc.). b. Potential erosion problem areas. c. The 13 elements of a SWPPP in Special Condition S9.D.1-13, including BMPs used to address each element. d. Construction phasing/sequence and general BMP implementation schedule. e. The actions to be taken if BMP performance goals are not achieved—for example, a contingency plan for additional treatment and/or storage of stormwater that would violate the water quality standards if discharged. f. Engineering calculations for ponds, treatment systems, and any other designed structures. When a treatment system requires engineering calculations, these calculations must be included in the SWPPP. Engineering calculations do not need to be included in the SWPPP for treatment systems that do not require such calculations. 2. The Permittee must modify the SWPPP if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is, or would be, ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The Permittee must then: a. Review the SWPPP for compliance with Special Condition S9 and make appropriate revisions within 7 days of the inspection or investigation. b. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible, addressing the problems no later than 10 days from the inspection or investigation. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when an extension is requested by a Permittee within the initial 10-day response period. c. Document BMP implementation and maintenance in the site log book. The Permittee must modify the SWPPP whenever there is a change in design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the State. C. Stormwater Best Management Practices (BMPs) BMPs must be consistent with: 1. Stormwater Management Manual for Western Washington (most current approved edition at the time this permit was issued), for sites west of the crest of the Cascade Mountains; or Construction Stormwater General Permit Page 25 2. Stormwater Management Manual for Eastern Washington (most current approved edition at the time this permit was issued), for sites east of the crest of the Cascade Mountains; or 3. Revisions to the manuals listed in Special Condition S9.C.1 & 2, or other stormwater management guidance documents or manuals which provide an equivalent level of pollution prevention, that are approved by Ecology and incorporated into this permit in accordance with the permit modification requirements of WAC 173-226-230; or 4. Documentation in the SWPPP that the BMPs selected provide an equivalent level of pollution prevention, compared to the applicable stormwater management manuals, including: a. The technical basis for the selection of all stormwater BMPs (scientific, technical studies, and/or modeling) that support the performance claims for the BMPs being selected. b. An assessment of how the selected BMP will satisfy AKART requirements and the applicable federal technology-based treatment requirements under 40 CFR part 125.3. D. SWPPP – Narrative Contents and Requirements The Permittee must include each of the 13 elements below in Special Condition S9.D.1-13 in the narrative of the SWPPP and implement them unless site conditions render the element unnecessary and the exemption from that element is clearly justified in the SWPPP. 1. Preserve Vegetation/Mark Clearing Limits a. Before beginning land-disturbing activities, including clearing and grading, clearly mark all clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the construction area. b. Retain the duff layer, native topsoil, and natural vegetation in an undisturbed state to the maximum degree practicable. 2. Establish Construction Access a. Limit construction vehicle access and exit to one route, if possible. b. Stabilize access points with a pad of quarry spalls, crushed rock, or other equivalent BMPs, to minimize tracking sediment onto roads. c. Locate wheel wash or tire baths on site, if the stabilized construction entrance is not effective in preventing tracking sediment onto roads. d. If sediment is tracked off site, clean the affected roadway thoroughly at the end of each day, or more frequently as necessary (for example, during wet weather). Remove sediment from roads by shoveling, sweeping, or pickup and transport of the sediment to a controlled sediment disposal area. e. Conduct street washing only after sediment removal in accordance with Special Condition S9.D.2.d. f. Control street wash wastewater by pumping back on site or otherwise preventing it from discharging into systems tributary to waters of the State. Construction Stormwater General Permit Page 26 3. Control Flow Rates a. Protect properties and waterways downstream of construction sites from erosion and the associated discharge of turbid waters due to increases in the velocity and peak volumetric flow rate of stormwater runoff from the project site, as required by local plan approval authority. b. Where necessary to comply with Special Condition S9.D.3.a, construct stormwater infiltration or detention BMPs as one of the first steps in grading. Assure that detention BMPs function properly before constructing site improvements (for example, impervious surfaces). c. If permanent infiltration ponds are used for flow control during construction, protect these facilities from sedimentation during the construction phase. 4. Install Sediment Controls The Permittee must design, install and maintain effective erosion controls and sediment controls to minimize the discharge of pollutants. At a minimum, the Permittee must: a. Construct sediment control BMPs (sediment ponds, traps, filters, infiltration facilities, etc.) as one of the first steps in grading. These BMPs must be functional before other land disturbing activities take place. b. Minimize sediment discharges from the site. The design, installation and maintenance of erosion and sediment controls must address factors such as the amount, frequency, intensity and duration of precipitation, the nature of resulting stormwater runoff, and soil characteristics, including the range of soil particle sizes expected to be present on the site. c. Direct stormwater runoff from disturbed areas through a sediment pond or other appropriate sediment removal BMP, before the runoff leaves a construction site or before discharge to an infiltration facility. Runoff from fully stabilized areas may be discharged without a sediment removal BMP, but must meet the flow control performance standard of Special Condition S9.D.3.a. d. Locate BMPs intended to trap sediment on site in a manner to avoid interference with the movement of juvenile salmonids attempting to enter off-channel areas or drainages. e. Provide and maintain natural buffers around surface waters, direct stormwater to vegetated areas to increase sediment removal and maximize stormwater infiltration, unless infeasible. f. Where feasible, design outlet structures that withdraw impounded stormwater from the surface to avoid discharging sediment that is still suspended lower in the water column. 5. Stabilize Soils a. The Permittee must stabilize exposed and unworked soils by application of effective BMPs that prevent erosion. Applicable BMPs include, but are not limited to: temporary and permanent seeding, sodding, mulching, plastic covering, erosion Construction Stormwater General Permit Page 27 control fabrics and matting, soil application of polyacrylamide (PAM), the early application of gravel base on areas to be paved, and dust control. b. The Permittee must control stormwater volume and velocity within the site to minimize soil erosion. c. The Permittee must control stormwater discharges, including both peak flow rates and total stormwater volume, to minimize erosion at outlets and to minimize downstream channel and stream bank erosion. d. Depending on the geographic location of the project, the Permittee must not allow soils to remain exposed and unworked for more than the time periods set forth below to prevent erosion. West of the Cascade Mountains Crest During the dry season (May 1 - September 30): 7 days During the wet season (October 1 - April 30): 2 days East of the Cascade Mountains Crest, except for Central Basin* During the dry season (July 1 - September 30): 10 days During the wet season (October 1 - June 30): 5 days The Central Basin*, East of the Cascade Mountains Crest During the dry Season (July 1 - September 30): 30 days During the wet season (October 1 - June 30): 15 days *Note: The Central Basin is defined as the portions of Eastern Washington with mean annual precipitation of less than 12 inches. e. The Permittee must stabilize soils at the end of the shift before a holiday or weekend if needed based on the weather forecast. f. The Permittee must stabilize soil stockpiles from erosion, protected with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. g. The Permittee must minimize the amount of soil exposed during construction activity. h. The Permittee must minimize the disturbance of steep slopes. i. The Permittee must minimize soil compaction and, unless infeasible, preserve topsoil. 6. Protect Slopes a. The Permittee must design and construct cut-and-fill slopes in a manner to minimize erosion. Applicable practices include, but are not limited to, reducing continuous length of slope with terracing and diversions, reducing slope steepness, and roughening slope surfaces (for example, track walking). b. The Permittee must divert off-site stormwater (run-on) or groundwater away from slopes and disturbed areas with interceptor dikes, pipes, and/or swales. Off-site stormwater should be managed separately from stormwater generated on the site. c. At the top of slopes, collect drainage in pipe slope drains or protected channels to prevent erosion. Construction Stormwater General Permit Page 28 i. West of the Cascade Mountains Crest: Temporary pipe slope drains must handle the peak 10-minute flow rate from a Type 1A, 10-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, 1-hour flow rate predicted by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydrologic analysis must use the existing land cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis must use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the Western Washington Hydrology Model (WWHM) to predict flows, bare soil areas should be modeled as "landscaped area.” ii. East of the Cascade Mountains Crest: Temporary pipe slope drains must handle the expected peak flow rate from a 6-month, 3-hour storm for the developed condition, referred to as the short duration storm. d. Place excavated material on the uphill side of trenches, consistent with safety and space considerations. e. Place check dams at regular intervals within constructed channels that are cut down a slope. 7. Protect Drain Inlets a. Protect all storm drain inlets made operable during construction so that stormwater runoff does not enter the conveyance system without first being filtered or treated to remove sediment. b. Clean or remove and replace inlet protection devices when sediment has filled one- third of the available storage (unless a different standard is specified by the product manufacturer). 8. Stabilize Channels and Outlets a. Design, construct and stabilize all on-site conveyance channels to prevent erosion from the following expected peak flows: i. West of the Cascade Mountains Crest: Channels must handle the peak 10- minute flow rate from a Type 1A, 10-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, 1-hour flow rate indicated by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydrologic analysis must use the existing land cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis must use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the WWHM to predict flows, bare soil areas should be modeled as "landscaped area.” ii. East of the Cascade Mountains Crest: Channels must handle the expected peak flow rate from a 6-month, 3-hour storm for the developed condition, referred to as the short duration storm. b. Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches at the outlets of all conveyance systems. Construction Stormwater General Permit Page 29 9. Control Pollutants Design, install, implement and maintain effective pollution prevention measures to minimize the discharge of pollutants. The Permittee must: a. Handle and dispose of all pollutants, including waste materials and demolition debris that occur on site in a manner that does not cause contamination of stormwater. b. Provide cover, containment, and protection from vandalism for all chemicals, liquid products, petroleum products, and other materials that have the potential to pose a threat to human health or the environment. Minimize storage of hazardous materials on-site. Safety Data Sheets (SDS) should be supplied for all materials stored. Chemicals should be kept in their original labeled containers. On-site fueling tanks must include secondary containment. Secondary containment means placing tanks or containers within an impervious structure capable of containing 110% of the volume of the largest tank within the containment structure. Double-walled tanks do not require additional secondary containment. c. Conduct maintenance, fueling, and repair of heavy equipment and vehicles using spill prevention and control measures. Clean contaminated surfaces immediately following any spill incident. d. Discharge wheel wash or tire bath wastewater to a separate on-site treatment system that prevents discharge to surface water, such as closed-loop recirculation or upland land application, or to the sanitary sewer with local sewer district approval. e. Apply fertilizers and pesticides in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Follow manufacturers’ label requirements for application rates and procedures. f. Use BMPs to prevent contamination of stormwater runoff by pH-modifying sources. The sources for this contamination include, but are not limited to: bulk cement, cement kiln dust, fly ash, new concrete washing and curing waters, recycled concrete stockpiles, waste streams generated from concrete grinding and sawing, exposed aggregate processes, dewatering concrete vaults, concrete pumping and mixer washout waters. (Also refer to the definition for "concrete wastewater" in Appendix A – Definitions.) g. Adjust the pH of stormwater or authorized non-stormwater if necessary to prevent an exceedance of groundwater and/or surface water quality standards. h. Assure that washout of concrete trucks is performed off-site or in designated concrete washout areas only. Do not wash out concrete truck drums onto the ground, or into storm drains, open ditches, streets, or streams. Washout of small concrete handling equipment may be disposed of in a formed area awaiting concrete where it will not contaminate surface or groundwater. Do not dump excess concrete on site, except in designated concrete washout areas. Concrete spillage or concrete discharge directly to groundwater or surface waters of the State is Construction Stormwater General Permit Page 30 prohibited. At no time shall concrete be washed off into the footprint of an area where an infiltration BMP will be installed. i. Obtain written approval from Ecology before using any chemical treatment, with the exception of CO2, dry ice or food grade vinegar, to adjust pH. j. Uncontaminated water from water-only based shaft drilling for construction of building, road, and bridge foundations may be infiltrated provided the wastewater is managed in a way that prohibits discharge to surface waters. Prior to infiltration, water from water-only based shaft drilling that comes into contact with curing concrete must be neutralized until pH is in the range of 6.5 to 8.5 (su). 10. Control Dewatering a. Permittees must discharge foundation, vault, and trench dewatering water, which have characteristics similar to stormwater runoff at the site, in conjunction with BMPs to reduce sedimentation before discharge to a sediment trap or sediment pond. b. Permittees may discharge clean, non-turbid dewatering water, such as well-point groundwater, to systems tributary to, or directly into surface waters of the State, as specified in Special Condition S9.D.8, provided the dewatering flow does not cause erosion or flooding of receiving waters. Do not route clean dewatering water through stormwater sediment ponds. Note that “surface waters of the State” may exist on a construction site as well as off site; for example, a creek running through a site. c. Other dewatering treatment or disposal options may include: i. Infiltration ii. Transport off site in a vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute state waters. iii. Ecology-approved on-site chemical treatment or other suitable treatment technologies (See S9.D.9.i, regarding chemical treatment written approval). iv. Sanitary or combined sewer discharge with local sewer district approval, if there is no other option. v. Use of a sedimentation bag with discharge to a ditch or swale for small volumes of localized dewatering. d. Permittees must handle highly turbid or contaminated dewatering water separately from stormwater. 11. Maintain BMPs a. Permittees must maintain and repair all temporary and permanent erosion and sediment control BMPs as needed to assure continued performance of their intended function in accordance with BMP specifications. b. Permittees must remove all temporary erosion and sediment control BMPs within 30 days after achieving final site stabilization or after the temporary BMPs are no longer needed. Construction Stormwater General Permit Page 31 12. Manage the Project a. Phase development projects to the maximum degree practicable and take into account seasonal work limitations. b. Inspect, maintain and repair all BMPs as needed to assure continued performance of their intended function. Conduct site inspections and monitoring in accordance with Special Condition S4. c. Maintain, update, and implement the SWPPP in accordance with Special Conditions S3, S4, and S9. 13. Protect Low Impact Development (LID) BMPs The primary purpose of on-site LID Stormwater Management is to reduce the disruption of the natural site hydrology through infiltration. LID BMPs are permanent facilities. a. Permittees must protect all LID BMPs (including, but not limited to, Bioretention and Rain Garden facilities) from sedimentation through installation and maintenance of erosion and sediment control BMPs on portions of the site that drain into the Bioretention and/or Rain Garden facilities. Restore the BMPs to their fully functioning condition if they accumulate sediment during construction. Restoring the facility must include removal of sediment and any sediment-laden bioretention/ rain garden soils, and replacing the removed soils with soils meeting the design specification. b. Permittees must maintain the infiltration capabilities of LID BMPs by protecting against compaction by construction equipment and foot traffic. Protect completed lawn and landscaped areas from compaction due to construction equipment. c. Permittees must control erosion and avoid introducing sediment from surrounding land uses onto permeable pavements. Do not allow muddy construction equipment on the base material or pavement. Do not allow sediment-laden runoff onto permeable pavements or base materials. d. Permittees must clean permeable pavements fouled with sediments or no longer passing an initial infiltration test using local stormwater manual methodology or the manufacturer’s procedures. e. Permittees must keep all heavy equipment off existing soils under LID BMPs that have been excavated to final grade to retain the infiltration rate of the soils. E. SWPPP – Map Contents and Requirements The Permittee’s SWPPP must also include a vicinity map or general location map (for example, a USGS quadrangle map, a portion of a county or city map, or other appropriate map) with enough detail to identify the location of the construction site and receiving waters within one mile of the site. The SWPPP must also include a legible site map (or maps) showing the entire construction site. The following features must be identified, unless not applicable due to site conditions. 1. The direction of north, property lines, and existing structures and roads. 2. Cut and fill slopes indicating the top and bottom of slope catch lines. Construction Stormwater General Permit Page 32 3. Approximate slopes, contours, and direction of stormwater flow before and after major grading activities. 4. Areas of soil disturbance and areas that will not be disturbed. 5. Locations of structural and nonstructural controls (BMPs) identified in the SWPPP. 6. Locations of off-site material, stockpiles, waste storage, borrow areas, and vehicle/equipment storage areas. 7. Locations of all surface water bodies, including wetlands. 8. Locations where stormwater or non-stormwater discharges off-site and/or to a surface waterbody, including wetlands. 9. Location of water quality sampling station(s), if sampling is required by state or local permitting authority. 10. Areas where final stabilization has been accomplished and no further construction-phase permit requirements apply. 11. Location or proposed location of LID facilities. S10. NOTICE OF TERMINATION Partial terminations of permit coverage are not authorized. A. The site is eligible for termination of coverage when it has met any of the following conditions: 1. The site has undergone final stabilization, the Permittee has removed all temporary BMPs (except biodegradable BMPs clearly manufactured with the intention for the material to be left in place and not interfere with maintenance or land use), and all stormwater discharges associated with construction activity have been eliminated; or 2. All portions of the site that have not undergone final stabilization per Special Condition S10.A.1 have been sold and/or transferred (per Special Condition S2.A), and the Permittee no longer has operational control of the construction activity; or 3. For residential construction only, the Permittee has completed temporary stabilization and the homeowners have taken possession of the residences. B. When the site is eligible for termination, the Permittee must submit a complete and accurate Notice of Termination (NOT) form, signed in accordance with General Condition G2, to: Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, WA 98504-7696 Construction Stormwater General Permit Page 33 When an electronic termination form is available, the Permittee may choose to submit a complete and accurate Notice of Termination (NOT) form through the Water Quality Permitting Portal rather than mailing a hardcopy as noted above. The termination is effective on the 31st calendar day following the date Ecology receives a complete NOT form, unless Ecology notifies the Permittee that termination request is denied because the Permittee has not met the eligibility requirements in Special Condition S10.A. Permittees are required to comply with all conditions and effluent limitations in the permit until the permit has been terminated. Permittees transferring the property to a new property owner or operator/Permittee are required to complete and submit the Notice of Transfer form to Ecology, but are not required to submit a Notice of Termination form for this type of transaction. Construction Stormwater General Permit Page 34 GENERAL CONDITIONS G1. DISCHARGE VIOLATIONS All discharges and activities authorized by this general permit must be consistent with the terms and conditions of this general permit. Any discharge of any pollutant more frequent than or at a level in excess of that identified and authorized by the general permit must constitute a violation of the terms and conditions of this permit. G2. SIGNATORY REQUIREMENTS A. All permit applications must bear a certification of correctness to be signed: 1. In the case of corporations, by a responsible corporate officer. 2. In the case of a partnership, by a general partner of a partnership. 3. In the case of sole proprietorship, by the proprietor. 4. In the case of a municipal, state, or other public facility, by either a principal executive officer or ranking elected official. B. All reports required by this permit and other information requested by Ecology (including NOIs, NOTs, and Transfer of Coverage forms) must be signed by a person described above or by a duly authorized representative of that person. A person is a duly authorized representative only if: 1. The authorization is made in writing by a person described above and submitted to Ecology. 2. The authorization specifies either an individual or a position having responsibility for the overall operation of the regulated facility, such as the position of plant manager, superintendent, position of equivalent responsibility, or an individual or position having overall responsibility for environmental matters. C. Changes to authorization. If an authorization under paragraph G2.B.2 above is no longer accurate because a different individual or position has responsibility for the overall operation of the facility, a new authorization satisfying the requirements of paragraph G2.B.2 above must be submitted to Ecology prior to or together with any reports, information, or applications to be signed by an authorized representative. D. Certification. Any person signing a document under this section must make the following certification: I certify under penalty of law, that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gathered and evaluated the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations. Construction Stormwater General Permit Page 35 G3. RIGHT OF INSPECTION AND ENTRY The Permittee must allow an authorized representative of Ecology, upon the presentation of credentials and such other documents as may be required by law: A. To enter upon the premises where a discharge is located or where any records are kept under the terms and conditions of this permit. B. To have access to and copy, at reasonable times and at reasonable cost, any records required to be kept under the terms and conditions of this permit. C. To inspect, at reasonable times, any facilities, equipment (including monitoring and control equipment), practices, methods, or operations regulated or required under this permit. D. To sample or monitor, at reasonable times, any substances or parameters at any location for purposes of assuring permit compliance or as otherwise authorized by the Clean Water Act. G4. GENERAL PERMIT MODIFICATION AND REVOCATION This permit may be modified, revoked and reissued, or terminated in accordance with the provisions of Chapter 173-226 WAC. Grounds for modification, revocation and reissuance, or termination include, but are not limited to, the following: A. When a change occurs in the technology or practices for control or abatement of pollutants applicable to the category of dischargers covered under this permit. B. When effluent limitation guidelines or standards are promulgated pursuant to the CWA or Chapter 90.48 RCW, for the category of dischargers covered under this permit. C. When a water quality management plan containing requirements applicable to the category of dischargers covered under this permit is approved, or D. When information is obtained that indicates cumulative effects on the environment from dischargers covered under this permit are unacceptable. G5. REVOCATION OF COVERAGE UNDER THE PERMIT Pursuant to Chapter 43.21B RCW and Chapter 173-226 WAC, the Director may terminate coverage for any discharger under this permit for cause. Cases where coverage may be terminated include, but are not limited to, the following: A. Violation of any term or condition of this permit. B. Obtaining coverage under this permit by misrepresentation or failure to disclose fully all relevant facts. C. A change in any condition that requires either a temporary or permanent reduction or elimination of the permitted discharge. D. Failure or refusal of the Permittee to allow entry as required in RCW 90.48.090. E. A determination that the permitted activity endangers human health or the environment, or contributes to water quality standards violations. F. Nonpayment of permit fees or penalties assessed pursuant to RCW 90.48.465 and Chapter 173-224 WAC. Construction Stormwater General Permit Page 36 G. Failure of the Permittee to satisfy the public notice requirements of WAC 173-226-130(5), when applicable. The Director may require any discharger under this permit to apply for and obtain coverage under an individual permit or another more specific general permit. Permittees who have their coverage revoked for cause according to WAC 173-226-240 may request temporary coverage under this permit during the time an individual permit is being developed, provided the request is made within ninety (90) days from the time of revocation and is submitted along with a complete individual permit application form. G6. REPORTING A CAUSE FOR MODIFICATION The Permittee must submit a new application, or a supplement to the previous application, whenever a material change to the construction activity or in the quantity or type of discharge is anticipated which is not specifically authorized by this permit. This application must be submitted at least sixty (60) days prior to any proposed changes. Filing a request for a permit modification, revocation and reissuance, or termination, or a notification of planned changes or anticipated noncompliance does not relieve the Permittee of the duty to comply with the existing permit until it is modified or reissued. G7. COMPLIANCE WITH OTHER LAWS AND STATUTES Nothing in this permit will be construed as excusing the Permittee from compliance with any applicable federal, state, or local statutes, ordinances, or regulations. G8. DUTY TO REAPPLY The Permittee must apply for permit renewal at least 180 days prior to the specified expiration date of this permit. The Permittee must reapply using the electronic application form (NOI) available on Ecology’s website. Permittees unable to submit electronically (for example, those who do not have an internet connection) must contact Ecology to request a waiver and obtain instructions on how to obtain a paper NOI. Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, WA 98504-7696 G9. REMOVED SUBSTANCE The Permittee must not re-suspend or reintroduce collected screenings, grit, solids, sludges, filter backwash, or other pollutants removed in the course of treatment or control of stormwater to the final effluent stream for discharge to state waters. G10. DUTY TO PROVIDE INFORMATION The Permittee must submit to Ecology, within a reasonable time, all information that Ecology may request to determine whether cause exists for modifying, revoking and reissuing, or terminating this permit or to determine compliance with this permit. The Permittee must also submit to Ecology, upon request, copies of records required to be kept by this permit [40 CFR 122.41(h)]. Construction Stormwater General Permit Page 37 G11. OTHER REQUIREMENTS OF 40 CFR All other requirements of 40 CFR 122.41 and 122.42 are incorporated in this permit by reference. G12. ADDITIONAL MONITORING Ecology may establish specific monitoring requirements in addition to those contained in this permit by administrative order or permit modification. G13. PENALTIES FOR VIOLATING PERMIT CONDITIONS Any person who is found guilty of willfully violating the terms and conditions of this permit shall be deemed guilty of a crime, and upon conviction thereof shall be punished by a fine of up to ten thousand dollars ($10,000) and costs of prosecution, or by imprisonment at the discretion of the court. Each day upon which a willful violation occurs may be deemed a separate and additional violation. Any person who violates the terms and conditions of a waste discharge permit shall incur, in addition to any other penalty as provided by law, a civil penalty in the amount of up to ten thousand dollars ($10,000) for every such violation. Each and every such violation shall be a separate and distinct offense, and in case of a continuing violation, every day’s continuance shall be deemed to be a separate and distinct violation. G14. UPSET Definition – “Upset” means an exceptional incident in which there is unintentional and temporary noncompliance with technology-based permit effluent limitations because of factors beyond the reasonable control of the Permittee. An upset does not include noncompliance to the extent caused by operational error, improperly designed treatment facilities, inadequate treatment facilities, lack of preventive maintenance, or careless or improper operation. An upset constitutes an affirmative defense to an action brought for noncompliance with such technology-based permit effluent limitations if the requirements of the following paragraph are met. A Permittee who wishes to establish the affirmative defense of upset must demonstrate, through properly signed, contemporaneous operating logs or other relevant evidence that: 1) an upset occurred and that the Permittee can identify the cause(s) of the upset; 2) the permitted facility was being properly operated at the time of the upset; 3) the Permittee submitted notice of the upset as required in Special Condition S5.F, and; 4) the Permittee complied with any remedial measures required under this permit. In any enforcement proceeding, the Permittee seeking to establish the occurrence of an upset has the burden of proof. G15. PROPERTY RIGHTS This permit does not convey any property rights of any sort, or any exclusive privilege. G16. DUTY TO COMPLY The Permittee must comply with all conditions of this permit. Any permit noncompliance constitutes a violation of the Clean Water Act and is grounds for enforcement action; for permit termination, revocation and reissuance, or modification; or denial of a permit renewal application. Construction Stormwater General Permit Page 38 G17. TOXIC POLLUTANTS The Permittee must comply with effluent standards or prohibitions established under Section 307(a) of the Clean Water Act for toxic pollutants within the time provided in the regulations that establish those standards or prohibitions, even if this permit has not yet been modified to incorporate the requirement. G18. PENALTIES FOR TAMPERING The Clean Water Act provides that any person who falsifies, tampers with, or knowingly renders inaccurate any monitoring device or method required to be maintained under this permit shall, upon conviction, be punished by a fine of not more than $10,000 per violation, or by imprisonment for not more than two years per violation, or by both. If a conviction of a person is for a violation committed after a first conviction of such person under this condition, punishment shall be a fine of not more than $20,000 per day of violation, or imprisonment of not more than four (4) years, or both. G19. REPORTING PLANNED CHANGES The Permittee must, as soon as possible, give notice to Ecology of planned physical alterations, modifications or additions to the permitted construction activity. The Permittee should be aware that, depending on the nature and size of the changes to the original permit, a new public notice and other permit process requirements may be required. Changes in activities that require reporting to Ecology include those that will result in: A. The permitted facility being determined to be a new source pursuant to 40 CFR 122.29(b). B. A significant change in the nature or an increase in quantity of pollutants discharged, including but not limited to: a 20% or greater increase in acreage disturbed by construction activity. C. A change in or addition of surface water(s) receiving stormwater or non-stormwater from the construction activity. D. A change in the construction plans and/or activity that affects the Permittee’s monitoring requirements in Special Condition S4. Following such notice, permit coverage may be modified, or revoked and reissued pursuant to 40 CFR 122.62(a) to specify and limit any pollutants not previously limited. Until such modification is effective, any new or increased discharge in excess of permit limits or not specifically authorized by this permit constitutes a violation. G20. REPORTING OTHER INFORMATION Where the Permittee becomes aware that it failed to submit any relevant facts in a permit application, or submitted incorrect information in a permit application or in any report to Ecology, it must promptly submit such facts or information. G21. REPORTING ANTICIPATED NON-COMPLIANCE The Permittee must give advance notice to Ecology by submission of a new application or supplement thereto at least forty-five (45) days prior to commencement of such discharges, of any facility expansions, production increases, or other planned changes, such as process modifications, in the permitted facility or activity which may result in noncompliance with permit limits or conditions. Any maintenance of facilities, which might necessitate unavoidable interruption of Construction Stormwater General Permit Page 39 operation and degradation of effluent quality, must be scheduled during non-critical water quality periods and carried out in a manner approved by Ecology. G22. REQUESTS TO BE EXCLUDED FROM COVERAGE UNDER THE PERMIT Any discharger authorized by this permit may request to be excluded from coverage under the general permit by applying for an individual permit. The discharger must submit to the Director an application as described in WAC 173-220-040 or WAC 173-216-070, whichever is applicable, with reasons supporting the request. These reasons will fully document how an individual permit will apply to the applicant in a way that the general permit cannot. Ecology may make specific requests for information to support the request. The Director will either issue an individual permit or deny the request with a statement explaining the reason for the denial. When an individual permit is issued to a discharger otherwise subject to the construction stormwater general permit, the applicability of the construction stormwater general permit to that Permittee is automatically terminated on the effective date of the individual permit. G23. APPEALS A. The terms and conditions of this general permit, as they apply to the appropriate class of dischargers, are subject to appeal by any person within 30 days of issuance of this general permit, in accordance with Chapter 43.21B RCW, and Chapter 173-226 WAC. B. The terms and conditions of this general permit, as they apply to an individual discharger, are appealable in accordance with Chapter 43.21B RCW within 30 days of the effective date of coverage of that discharger. Consideration of an appeal of general permit coverage of an individual discharger is limited to the general permit’s applicability or nonapplicability to that individual discharger. C. The appeal of general permit coverage of an individual discharger does not affect any other dischargers covered under this general permit. If the terms and conditions of this general permit are found to be inapplicable to any individual discharger(s), the matter shall be remanded to Ecology for consideration of issuance of an individual permit or permits. G24. SEVERABILITY The provisions of this permit are severable, and if any provision of this permit, or application of any provision of this permit to any circumstance, is held invalid, the application of such provision to other circumstances, and the remainder of this permit shall not be affected thereby. G25. BYPASS PROHIBITED A. Bypass Procedures Bypass, which is the intentional diversion of waste streams from any portion of a treatment facility, is prohibited for stormwater events below the design criteria for stormwater management. Ecology may take enforcement action against a Permittee for bypass unless one of the following circumstances (1, 2, 3 or 4) is applicable. 1. Bypass of stormwater is consistent with the design criteria and part of an approved management practice in the applicable stormwater management manual. 2. Bypass for essential maintenance without the potential to cause violation of permit limits or conditions. Construction Stormwater General Permit Page 40 Bypass is authorized if it is for essential maintenance and does not have the potential to cause violations of limitations or other conditions of this permit, or adversely impact public health. 3. Bypass of stormwater is unavoidable, unanticipated, and results in noncompliance of this permit. This bypass is permitted only if: a. Bypass is unavoidable to prevent loss of life, personal injury, or severe property damage. “Severe property damage” means substantial physical damage to property, damage to the treatment facilities which would cause them to become inoperable, or substantial and permanent loss of natural resources which can reasonably be expected to occur in the absence of a bypass. b. There are no feasible alternatives to the bypass, such as the use of auxiliary treatment facilities, retention of untreated wastes, maintenance during normal periods of equipment downtime (but not if adequate backup equipment should have been installed in the exercise of reasonable engineering judgment to prevent a bypass which occurred during normal periods of equipment downtime or preventative maintenance), or transport of untreated wastes to another treatment facility. c. Ecology is properly notified of the bypass as required in Special Condition S5.F of this permit. 4. A planned action that would cause bypass of stormwater and has the potential to result in noncompliance of this permit during a storm event. The Permittee must notify Ecology at least thirty (30) days before the planned date of bypass. The notice must contain: a. A description of the bypass and its cause b. An analysis of all known alternatives which would eliminate, reduce, or mitigate the need for bypassing. c. A cost-effectiveness analysis of alternatives including comparative resource damage assessment. d. The minimum and maximum duration of bypass under each alternative. e. A recommendation as to the preferred alternative for conducting the bypass. f. The projected date of bypass initiation. g. A statement of compliance with SEPA. h. A request for modification of water quality standards as provided for in WAC 173- 201A-110, if an exceedance of any water quality standard is anticipated. i. Steps taken or planned to reduce, eliminate, and prevent reoccurrence of the bypass. 5. For probable construction bypasses, the need to bypass is to be identified as early in the planning process as possible. The analysis required above must be considered during Construction Stormwater General Permit Page 41 preparation of the Stormwater Pollution Prevention Plan (SWPPP) and must be included to the extent practical. In cases where the probable need to bypass is determined early, continued analysis is necessary up to and including the construction period in an effort to minimize or eliminate the bypass. Ecology will consider the following before issuing an administrative order for this type bypass: a. If the bypass is necessary to perform construction or maintenance-related activities essential to meet the requirements of this permit. b. If there are feasible alternatives to bypass, such as the use of auxiliary treatment facilities, retention of untreated wastes, stopping production, maintenance during normal periods of equipment down time, or transport of untreated wastes to another treatment facility. c. If the bypass is planned and scheduled to minimize adverse effects on the public and the environment. After consideration of the above and the adverse effects of the proposed bypass and any other relevant factors, Ecology will approve, conditionally approve, or deny the request. The public must be notified and given an opportunity to comment on bypass incidents of significant duration, to the extent feasible. Approval of a request to bypass will be by administrative order issued by Ecology under RCW 90.48.120. B. Duty to Mitigate The Permittee is required to take all reasonable steps to minimize or prevent any discharge or sludge use or disposal in violation of this permit that has a reasonable likelihood of adversely affecting human health or the environment. Construction Stormwater General Permit Page 42 APPENDIX A – DEFINITIONS AKART is an acronym for “All Known, Available, and Reasonable methods of prevention, control, and Treatment.” AKART represents the most current methodology that can be reasonably required for preventing, controlling, or abating the pollutants and controlling pollution associated with a discharge. Applicable TMDL means a TMDL for turbidity, fine sediment, high pH, or phosphorus, which was completed and approved by EPA before January 1, 2021, or before the date the operator’s complete permit application is received by Ecology, whichever is later. TMDLs completed after a complete permit application is received by Ecology become applicable to the Permittee only if they are imposed through an administrative order by Ecology, or through a modification of permit coverage. Applicant means an operator seeking coverage under this permit. Benchmark means a pollutant concentration used as a permit threshold, below which a pollutant is considered unlikely to cause a water quality violation, and above which it may. When pollutant concentrations exceed benchmarks, corrective action requirements take effect. Benchmark values are not water quality standards and are not numeric effluent limitations; they are indicator values. Best Management Practices (BMPs) means schedules of activities, prohibitions of practices, maintenance procedures, and other physical, structural and/or managerial practices to prevent or reduce the pollution of waters of the State. BMPs include treatment systems, operating procedures, and practices to control stormwater associated with construction activity, spillage or leaks, sludge or waste disposal, or drainage from raw material storage. Buffer means an area designated by a local jurisdiction that is contiguous to and intended to protect a sensitive area. Bypass means the intentional diversion of waste streams from any portion of a treatment facility. Calendar Day A period of 24 consecutive hours starting at 12:00 midnight and ending the following 12:00 midnight. Calendar Week (same as Week) means a period of seven consecutive days starting at 12:01 a.m. (0:01 hours) on Sunday. Certified Erosion and Sediment Control Lead (CESCL) means a person who has current certification through an approved erosion and sediment control training program that meets the minimum training standards established by Ecology (See BMP C160 in the SWMM). Chemical Treatment means the addition of chemicals to stormwater and/or authorized non-stormwater prior to filtration and discharge to surface waters. Clean Water Act (CWA) means the Federal Water Pollution Control Act enacted by Public Law 92-500, as amended by Public Laws 95-217, 95-576, 96-483, and 97-117; USC 1251 et seq. Combined Sewer means a sewer which has been designed to serve as a sanitary sewer and a storm sewer, and into which inflow is allowed by local ordinance. Construction Stormwater General Permit Page 43 Common Plan of Development or Sale means a site where multiple separate and distinct construction activities may be taking place at different times on different schedules and/or by different contractors, but still under a single plan. Examples include: 1) phased projects and projects with multiple filings or lots, even if the separate phases or filings/lots will be constructed under separate contract or by separate owners (e.g., a development where lots are sold to separate builders); 2) a development plan that may be phased over multiple years, but is still under a consistent plan for long-term development; 3) projects in a contiguous area that may be unrelated but still under the same contract, such as construction of a building extension and a new parking lot at the same facility; and 4) linear projects such as roads, pipelines, or utilities. If the project is part of a common plan of development or sale, the disturbed area of the entire plan must be used in determining permit requirements. Composite Sample means a mixture of grab samples collected at the same sampling point at different times, formed either by continuous sampling or by mixing discrete samples. May be "time-composite" (collected at constant time intervals) or "flow-proportional" (collected either as a constant sample volume at time intervals proportional to stream flow, or collected by increasing the volume of each aliquot as the flow increases while maintaining a constant time interval between the aliquots. Concrete Wastewater means any water used in the production, pouring and/or clean-up of concrete or concrete products, and any water used to cut, grind, wash, or otherwise modify concrete or concrete products. Examples include water used for or resulting from concrete truck/mixer/pumper/tool/chute rinsing or washing, concrete saw cutting and surfacing (sawing, coring, grinding, roughening, hydro- demolition, bridge and road surfacing). When stormwater comingles with concrete wastewater, the resulting water is considered concrete wastewater and must be managed to prevent discharge to waters of the State, including groundwater. Construction Activity means land disturbing operations including clearing, grading or excavation which disturbs the surface of the land (including off-site disturbance acreage related to construction-support activity). Such activities may include road construction, construction of residential houses, office buildings, or industrial buildings, site preparation, soil compaction, movement and stockpiling of topsoils, and demolition activity. Construction Support Activity means off-site acreage that will be disturbed as a direct result of the construction project and will discharge stormwater. For example, off-site equipment staging yards, material storage areas, borrow areas, and parking areas. Contaminant means any hazardous substance that does not occur naturally or occurs at greater than natural background levels. See definition of “hazardous substance” and WAC 173-340-200. Contaminated soil means soil which contains contaminants, pollutants, or hazardous substances that do not occur naturally or occur at levels greater than natural background. Contaminated groundwater means groundwater which contains contaminants, pollutants, or hazardous substances that do not occur naturally or occur at levels greater than natural background. Demonstrably Equivalent means that the technical basis for the selection of all stormwater BMPs is documented within a SWPPP, including: 1. The method and reasons for choosing the stormwater BMPs selected. 2. The pollutant removal performance expected from the BMPs selected. Construction Stormwater General Permit Page 44 3. The technical basis supporting the performance claims for the BMPs selected, including any available data concerning field performance of the BMPs selected. 4. An assessment of how the selected BMPs will comply with state water quality standards. 5. An assessment of how the selected BMPs will satisfy both applicable federal technology-based treatment requirements and state requirements to use all known, available, and reasonable methods of prevention, control, and treatment (AKART). Department means the Washington State Department of Ecology. Detention means the temporary storage of stormwater to improve quality and/or to reduce the mass flow rate of discharge. Dewatering means the act of pumping groundwater or stormwater away from an active construction site. Director means the Director of the Washington State Department of Ecology or his/her authorized representative. Discharger means an owner or operator of any facility or activity subject to regulation under Chapter 90.48 RCW or the Federal Clean Water Act. Domestic Wastewater means water carrying human wastes, including kitchen, bath, and laundry wastes from residences, buildings, industrial establishments, or other places, together with such groundwater infiltration or surface waters as may be present. Ecology means the Washington State Department of Ecology. Engineered Soils means the use of soil amendments including, but not limited, to Portland cement treated base (CTB), cement kiln dust (CKD), or fly ash to achieve certain desirable soil characteristics. Equivalent BMPs means operational, source control, treatment, or innovative BMPs which result in equal or better quality of stormwater discharge to surface water or to groundwater than BMPs selected from the SWMM. Erosion means the wearing away of the land surface by running water, wind, ice, or other geological agents, including such processes as gravitational creep. Erosion and Sediment Control BMPs means BMPs intended to prevent erosion and sedimentation, such as preserving natural vegetation, seeding, mulching and matting, plastic covering, filter fences, sediment traps, and ponds. Erosion and sediment control BMPs are synonymous with stabilization and structural BMPs. Federal Operator is an entity that meets the definition of “Operator” in this permit and is either any department, agency or instrumentality of the executive, legislative, and judicial branches of the Federal government of the United States, or another entity, such as a private contractor, performing construction activity for any such department, agency, or instrumentality. Final Stabilization (same as fully stabilized or full stabilization) means the completion of all soil disturbing activities at the site and the establishment of permanent vegetative cover, or equivalent permanent stabilization measures (such as pavement, riprap, gabions, or geotextiles) which will prevent erosion. See the applicable Stormwater Management Manual for more information on vegetative cover expectations and equivalent permanent stabilization measures. Construction Stormwater General Permit Page 45 Groundwater means water in a saturated zone or stratum beneath the land surface or a surface waterbody. Hazardous Substance means any dangerous or extremely hazardous waste as defined in RCW 70.105.010 (5) and (6), or any dangerous or extremely dangerous waste as designated by rule under chapter 70.105 RCW; any hazardous sub-stance as defined in RCW 70.105.010(14) or any hazardous substance as defined by rule under chapter 70.105 RCW; any substance that, on the effective date of this section, is a hazardous substance under section 101(14) of the federal cleanup law, 42U.S.C., Sec. 9601(14); petroleum or petroleum products; and any substance or category of substances, including solid waste decomposition products, determined by the director by rule to present a threat to human health or the environment if released into the environment. The term hazardous substance does not include any of the following when contained in an underground storage tank from which there is not a release: crude oil or any fraction thereof or petroleum, if the tank is in compliance with all applicable federal, state, and local law. Injection Well means a well that is used for the subsurface emplacement of fluids. (See Well.) Jurisdiction means a political unit such as a city, town or county; incorporated for local self-government. National Pollutant Discharge Elimination System (NPDES) means the national program for issuing, modifying, revoking and reissuing, terminating, monitoring, and enforcing permits, and imposing and enforcing pretreatment requirements, under sections 307, 402, 318, and 405 of the Federal Clean Water Act, for the discharge of pollutants to surface waters of the State from point sources. These permits are referred to as NPDES permits and, in Washington State, are administered by the Washington State Department of Ecology. Notice of Intent (NOI) means the application for, or a request for coverage under this general permit pursuant to WAC 173-226-200. Notice of Termination (NOT) means a request for termination of coverage under this general permit as specified by Special Condition S10 of this permit. Operator means any party associated with a construction project that meets either of the following two criteria: • The party has operational control over construction plans and specifications, including the ability to make modifications to those plans and specifications; or • The party has day-to-day operational control of those activities at a project that are necessary to ensure compliance with a SWPPP for the site or other permit conditions (e.g., they are authorized to direct workers at a site to carry out activities required by the SWPPP or comply with other permit conditions). Permittee means individual or entity that receives notice of coverage under this general permit. pH means a liquid’s measure of acidity or alkalinity. A pH of 7 is defined as neutral. Large variations above or below this value are considered harmful to most aquatic life. pH Monitoring Period means the time period in which the pH of stormwater runoff from a site must be tested a minimum of once every seven days to determine if stormwater pH is between 6.5 and 8.5. Construction Stormwater General Permit Page 46 Point Source means any discernible, confined, and discrete conveyance, including but not limited to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, and container from which pollutants are or may be discharged to surface waters of the State. This term does not include return flows from irrigated agriculture. (See the Fact Sheet for further explanation) Pollutant means dredged spoil, solid waste, incinerator residue, filter backwash, sewage, garbage, domestic sewage sludge (biosolids), munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt, and industrial, municipal, and agricultural waste. This term does not include sewage from vessels within the meaning of section 312 of the CWA, nor does it include dredged or fill material discharged in accordance with a permit issued under section 404 of the CWA. Pollution means contamination or other alteration of the physical, chemical, or biological properties of waters of the State; including change in temperature, taste, color, turbidity, or odor of the waters; or such discharge of any liquid, gaseous, solid, radioactive or other substance into any waters of the State as will or is likely to create a nuisance or render such waters harmful, detrimental or injurious to the public health, safety or welfare; or to domestic, commercial, industrial, agricultural, recreational, or other legitimate beneficial uses; or to livestock, wild animals, birds, fish or other aquatic life. Process Wastewater means any non-stormwater which, during manufacturing or processing, comes into direct contact with or results from the production or use of any raw material, intermediate product, finished product, byproduct, or waste product. If stormwater commingles with process wastewater, the commingled water is considered process wastewater. Receiving Water means the waterbody at the point of discharge. If the discharge is to a storm sewer system, either surface or subsurface, the receiving water is the waterbody to which the storm system discharges. Systems designed primarily for other purposes such as for groundwater drainage, redirecting stream natural flows, or for conveyance of irrigation water/return flows that coincidentally convey stormwater are considered the receiving water. Representative means a stormwater or wastewater sample which represents the flow and characteristics of the discharge. Representative samples may be a grab sample, a time-proportionate composite sample, or a flow proportionate sample. Ecology’s Construction Stormwater Monitoring Manual provides guidance on representative sampling. Responsible Corporate Officer for the purpose of signatory authority means: (i) a president, secretary, treasurer, or vice-president of the corporation in charge of a principal business function, or any other person who performs similar policy- or decision-making functions for the corporation, or (ii) the manager of one or more manufacturing, production, or operating facilities, provided, the manager is authorized to make management decisions which govern the operation of the regulated facility including having the explicit or implicit duty of making major capital investment recommendations, and initiating and directing other comprehensive measures to assure long term environmental compliance with environmental laws and regulations; the manager can ensure that the necessary systems are established or actions taken to gather complete and accurate information for permit application requirements; and where authority to sign documents has been assigned or delegated to the manager in accordance with corporate procedures (40 CFR 122.22). Sanitary Sewer means a sewer which is designed to convey domestic wastewater. Construction Stormwater General Permit Page 47 Sediment means the fragmented material that originates from the weathering and erosion of rocks or unconsolidated deposits, and is transported by, suspended in, or deposited by water. Sedimentation means the depositing or formation of sediment. Sensitive Area means a waterbody, wetland, stream, aquifer recharge area, or channel migration zone. SEPA (State Environmental Policy Act) means the Washington State Law, RCW 43.21C.020, intended to prevent or eliminate damage to the environment. Significant Amount means an amount of a pollutant in a discharge that is amenable to available and reasonable methods of prevention or treatment; or an amount of a pollutant that has a reasonable potential to cause a violation of surface or groundwater quality or sediment management standards. Significant Concrete Work means greater than 1000 cubic yards placed or poured concrete or recycled concrete used over the life of a project. Significant Contributor of Pollutants means a facility determined by Ecology to be a contributor of a significant amount(s) of a pollutant(s) to waters of the State of Washington. Site means the land or water area where any "facility or activity" is physically located or conducted. Source Control BMPs means physical, structural or mechanical devices or facilities that are intended to prevent pollutants from entering stormwater. A few examples of source control BMPs are erosion control practices, maintenance of stormwater facilities, constructing roofs over storage and working areas, and directing wash water and similar discharges to the sanitary sewer or a dead end sump. Stabilization means the application of appropriate BMPs to prevent the erosion of soils, such as, temporary and permanent seeding, vegetative covers, mulching and matting, plastic covering and sodding. See also the definition of Erosion and Sediment Control BMPs. Storm Drain means any drain which drains directly into a storm sewer system, usually found along roadways or in parking lots. Storm Sewer System means a means a conveyance, or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains designed or used for collecting or conveying stormwater. This does not include systems which are part of a combined sewer or Publicly Owned Treatment Works (POTW), as defined at 40 CFR 122.2. Stormwater means that portion of precipitation that does not naturally percolate into the ground or evaporate, but flows via overland flow, interflow, pipes, and other features of a stormwater drainage system into a defined surface waterbody, or a constructed infiltration facility. Stormwater Management Manual (SWMM) or Manual means the technical Manual published by Ecology for use by local governments that contain descriptions of and design criteria for BMPs to prevent, control, or treat pollutants in stormwater. Stormwater Pollution Prevention Plan (SWPPP) means a documented plan to implement measures to identify, prevent, and control the contamination of point source discharges of stormwater. Construction Stormwater General Permit Page 48 Surface Waters of the State includes lakes, rivers, ponds, streams, inland waters, salt waters, and all other surface waters and water courses within the jurisdiction of the state of Washington. Temporary Stabilization means the exposed ground surface has been covered with appropriate materials to provide temporary stabilization of the surface from water or wind erosion. Materials include, but are not limited to, mulch, riprap, erosion control mats or blankets and temporary cover crops. Seeding alone is not considered stabilization. Temporary stabilization is not a substitute for the more permanent “final stabilization.” Total Maximum Daily Load (TMDL) means a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet state water quality standards. Percentages of the total maximum daily load are allocated to the various pollutant sources. A TMDL is the sum of the allowable loads of a single pollutant from all contributing point and nonpoint sources. The TMDL calculations must include a "margin of safety" to ensure that the waterbody can be protected in case there are unforeseen events or unknown sources of the pollutant. The calculation must also account for seasonable variation in water quality. Transfer of Coverage (TOC) means a request for transfer of coverage under this general permit as specified by Special Condition S2.A of this permit. Treatment BMPs means BMPs that are intended to remove pollutants from stormwater. A few examples of treatment BMPs are detention ponds, oil/water separators, biofiltration, and constructed wetlands. Transparency means a measurement of water clarity in centimeters (cm), using a 60 cm transparency tube. The transparency tube is used to estimate the relative clarity or transparency of water by noting the depth at which a black and white Secchi disc becomes visible when water is released from a value in the bottom of the tube. A transparency tube is sometimes referred to as a “turbidity tube.” Turbidity means the clarity of water expressed as nephelometric turbidity units (NTUs) and measured with a calibrated turbidimeter. Uncontaminated means free from any contaminant. See definition of “contaminant” and WAC 173-340-200. Upset means an exceptional incident in which there is unintentional and temporary noncompliance with technology-based permit effluent limitations because of factors beyond the reasonable control of the Permittee. An upset does not include noncompliance to the extent caused by operational error, improperly designed treatment facilities, inadequate treatment facilities, lack of preventive maintenance, or careless or improper operation. Waste Load Allocation (WLA) means the portion of a receiving water’s loading capacity that is allocated to one of its existing or future point sources of pollution. WLAs constitute a type of water quality based effluent limitation (40 CFR 130.2[h]). Water-Only Based Shaft Drilling is a shaft drilling process that uses water only and no additives are involved in the drilling of shafts for construction of building, road, or bridge foundations. Water Quality means the chemical, physical, and biological characteristics of water, usually with respect to its suitability for a particular purpose. Waters of the State includes those waters as defined as "waters of the United States" in 40 CFR Subpart 122.2 within the geographic boundaries of Washington State and "waters of the State" as defined in Chapter 90.48 RCW, which include lakes, rivers, ponds, streams, inland waters, underground waters, salt Construction Stormwater General Permit Page 49 waters, and all other surface waters and water courses within the jurisdiction of the state of Washington. Well means a bored, drilled or driven shaft, or dug hole whose depth is greater than the largest surface dimension. (See Injection Well.) Wheel Wash Wastewater means any water used in, or resulting from the operation of, a tire bath or wheel wash (BMP C106: Wheel Wash), or other structure or practice that uses water to physically remove mud and debris from vehicles leaving a construction site and prevent track-out onto roads. When stormwater comingles with wheel wash wastewater, the resulting water is considered wheel wash wastewater and must be managed according to Special Condition S9.D.9. Construction Stormwater General Permit Page 50 APPENDIX B – ACRONYMS AKART All Known, Available, and Reasonable Methods of Prevention, Control, and Treatment BMP Best Management Practice CESCL Certified Erosion and Sediment Control Lead CFR Code of Federal Regulations CKD Cement Kiln Dust cm Centimeters CPD Common Plan of Development CTB Cement-Treated Base CWA Clean Water Act DMR Discharge Monitoring Report EPA Environmental Protection Agency ERTS Environmental Report Tracking System ESC Erosion and Sediment Control FR Federal Register LID Low Impact Development NOI Notice of Intent NOT Notice of Termination NPDES National Pollutant Discharge Elimination System NTU Nephelometric Turbidity Unit RCW Revised Code of Washington SEPA State Environmental Policy Act SWMM Stormwater Management Manual SWPPP Stormwater Pollution Prevention Plan TMDL Total Maximum Daily Load UIC Underground Injection Control USC United States Code USEPA United States Environmental Protection Agency WAC Washington Administrative Code WQ Water Quality WWHM Western Washington Hydrology Model G. 303(d) List Waterbodies / TMDL Waterbodies Information N/A H. Contaminated Site Information N/A I. Engineering Calculations N/A Sediment Trap 1 C (pavement)0.9 C (grass shoulders)0.25 C (gravel)0.5 Sediment 1 A pavement (ac)0.018 grass (ac)2.2087 A gravel (ac)0.040 A total (ac)2.267 Ct 0.260 Q (cfs)0.8344365 SA (sf)1738 m 3.47 n 0.556 I 1.4180846 K (ft/min)600 K (m/min)200 DA-1 L (ft)349 K (ft/min)600 S (ft/ft)0.0225 H (ft)1 Tt (min)3.8777778 Tt (min)all < 5 min Tc (min)5 Sediment Trap Calculations Table 4.18, SWMMEW Table 4.19, SWMMEW Table 4.20, SWMMEW Circle K Drainage Exhibit Project: CK Yelm & Killion Kimley-Horn and Associates, Inc. Yelm, WA Stormwater Report November 2024 Appendix H: Operations and Maintenance (O&M) Manual Operation and Maintenance Manual for Circle K Stores, Inc. Signature: ______________________________ Operation and Maintenance Manual Circle K Stores, Inc. 2 Operation and Maintenance Manual Objective The objective of this Operation and Maintenance Manual is to ensure that Stormwater Management BMPs are properly maintained and operated according to the Thurston County Drainage Design and Erosion Control Manual (DDECM) and 2024 Stormwater Management Manual for Western Washington (2024SWMMWW). Site Specific Details This site contains the following structural BMP facilities that must be operated and maintained according to this manual: ·Bioretention o There are two proposed bioretention ponds on the Northwestern and Southwestern side of the site that receives stormwater from stormwater catch basins. o Refer to Table V-A.2, V-A.23 in Appendix A for proper operation and maintenance guidelines. ·Stormwater Catch Basin Inlets o These are present throughout the site, usually at distinct low points. These facilities will capture and convey stormwater runoff to the correct outfall. o Refer to Table V-A.7 in Appendix A for proper operation and maintenance guidelines. ·Biofiltration Swales o These are present along the perimeter of the site in order to improve water quality, reduce volume of runoff, and to direct runoff to the one bioretention pond onsite. o Refer to Table V-A.10 in Appendix A for proper operation and maintenance guidelines. ·Oil / Water Separator o This is present to onsite to capture runoff from the areas where vehicle fueling is occurring for treatment of stormwater prior to discharge into Bioretention areas. o Refer to Table V-A.19 in Appendix A for proper operation and maintenance guidelines. Operation and Maintenance Responsibilities This operation and maintenance manual is consistent with the provisions in Volume V for the proposed Runoff Treatment BMPs. The party (or parties) responsible for maintenance and operation shall be the current property owners. A copy of this operation and maintenance manual shall be retained on site or within reasonable access to the site and shall be transferred with the property to the new owner. A log of maintenance activity that indicates what actions were taken shall be kept and be available for inspection by the local government. See Maintenance Activity Log Template for reference. Note: The site’s stormwater outfall is critical to a functional and compliant stormwater network. The operation and maintenance of the outfall is the responsibility of the current property owner. Property Owner: Killion Crossing LLC Operation and Maintenance Manual Circle K Stores, Inc. 3 Maintenance Activity Log Template BMP Date Maintenance Task Completed Notes Operation and Maintenance Manual Circle K Stores, Inc. 4 Appendix A: 2024 Stormwater Management Manual for Western Washington Appendix V-A: BMP Maintenance Tables V-A.1 How To Use The BMP Maintenance Tables The Best Management Practice (BMP) specific maintenance criteria contained in this appendix are intended to be conditions for determining if maintenance actions are required as identified through inspection. They are not  intended to be measures of the required condition of the BMP at all times between inspections. In other words, exceeding these conditions at any time between inspections and/or maintenance does not automatically constitute  a violation of these criteria. However, based on inspection observations, the inspection and maintenance schedules shall be adjusted to minimize the length of time that a BMP is in a condition that requires a maintenance  action. V-A.2 Maintenance Standards - Detention Ponds Maintenance Com- ponent Defect Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed General Trash and Debris   Any trash and debris which exceed 5 cubic feet (cf) per 1,000 square feet (sf), which is  about equal to the amount of trash it would take to fill up one standard size garbage can. In  general, there should be no visual evidence of dumping.  If less than the threshold above, all trash and debris will be removed as part of next sched- uled maintenance. Trash and debris cleared from site  Poisonous Veget- ation and Noxious  Weeds    Any poisonous or nuisance vegetation which may constitute a hazard to maintenance per- sonnel or the public. Any evidence of noxious weeds as defined by State or local regulations. (Apply requirements of adopted integrated pest management (IPM) policies for the use of  herbicides). No danger of poisonous vegetation where maintenance personnel or the public might normally be.  (Coordinate with local health department). Complete eradication of noxious weeds may not be possible. Compliance with State or local eradication  policies required Contaminants and  Pollution  Any evidence of oil, gasoline, contaminants or other pollutants. (Coordinate removal/cleanup with local water quality response agency). No contaminants or pollutants present. Rodent Holes Any evidence of rodent holes if the pond is acting as a dam or berm, or any evidence of  water piping through dam or berm via rodent holes. Rodents destroyed and dam or berm repaired. (Coordinate with local health department and Ecology  Dam Safety Office if pond exceeds 10 acre-feet).  Beaver Dams Dam results in change or function of the BMP. BMP is returned to design function. (Coordinate trapping of beavers and removal of dams with appropriate permitting agencies). Insects When insects such as wasps and hornets interfere with maintenance activities.  Insects destroyed or removed from site. Apply insecticides in compliance with adopted IPM policies Tree Growth and  Hazard Trees   Tree growth does not allow maintenance and inspection access, or interferes with main- tenance activity (i.e. slope mowing, silt removal, vactoring, or equipment movements). If  trees are not interfering with access or maintenance, do not remove. If dead, diseased, or dying trees are identified. (Use a certified arborist to determine health of tree or removal requirements) Trees do not hinder maintenance activities. Harvested trees should be recycled into mulch or other bene- ficial uses (e.g. alders for firewood).  Remove hazard trees. Side Slopes of Pond Erosion  Eroded damage over 2 inches deep where cause of damage is still present or where there  is potential for continued erosion.  Slopes should be stabilized using appropriate erosion control measure(s); e.g. rock reinforcement, plant- ing of grass, compaction. Table V-A.1: Maintenance Standards - Detention Ponds 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1173 Maintenance Com- ponent Defect Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed Any erosion observed on a compacted berm embankment.If erosion is occurring on compacted berms a licensed engineer in the state of Washington should be  consulted to resolve source of erosion. Storage Area Sediment Accumulated sediment that exceeds 10% of the designed pond depth unless otherwise  specified or affects inletting or outletting condition of the BMP.  Sediment cleaned out to designed pond shape and depth; pond reseeded if necessary to control  erosion.  Liner (if applicable) Liner is visible and has more than three 0.25-inch holes in it. Liner repaired or replaced. Liner is fully covered.  Pond Berms (Dikes) Settlements    Any part of berm which has settled 4 inches lower than the design elevation. If settlement is apparent, measure berm to determine amount of settlement. Settling can be an indication of more severe problems with the berm or outlet works. A  licensed engineer in the state of Washington should be consulted to determine the source  of the settlement. Dike is built back to the design elevation.   Piping   Discernible water flow through pond berm. Ongoing erosion with potential for erosion to  continue. (Recommend a geotechnical engineer be called in to inspect and evaluate condition and  recommend repair of condition. Piping eliminated. Erosion potential resolved.  Emergency Over- flow/Spillway Tree Growth     Tree growth on emergency spillways creates blockage problems and may cause failure of  the berm due to uncontrolled overtopping. Tree growth on berms over 4 feet in height may lead to piping through the berm which  could lead to failure of the berm. Trees should be removed. If root system is small (base less than 4 inches) the root system may be left in  place. Otherwise the roots should be removed and the berm restored. A licensed engineer in the state of  Washington should be consulted for proper berm/spillway restoration.  Piping   Discernible water flow through pond berm. Ongoing erosion with potential for erosion to  continue. (Recommend a geotechnical engineer be called in to inspect and evaluate condition and  recommend repair of condition. Piping eliminated. Erosion potential resolved.   Emergency Over- flow/Spillway   Only one layer of rock exists above native soil in area five square feet or larger, or any  exposure of native soil at the top of outflow path of spillway. (Riprap on inside slopes need not be replaced.) Rocks and pad depth are restored to design standards.  Erosion See Side Slopes of Pond   Table V-A.1: Maintenance Standards - Detention Ponds (continued) V-A.3 Maintenance Standards - Infiltration Maintenance Component Defect Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed General Trash & Debris See V-A.2 Maintenance Standards - Detention Ponds Poisonous/Noxious Veget- ation See V-A.2 Maintenance Standards - Detention Ponds Contaminants and Pollution See V-A.2 Maintenance Standards - Detention Ponds Table V-A.2: Maintenance Standards - Infiltration 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1174 Maintenance Com- ponent Defect Condition When Maintenance is Needed Results Expected When Maintenance is Performed Clean-out Gate Damaged or Missing Clean-out gate is  not watertight or is missing. Gate cannot be  moved up and down by one maintenance person. Chain/rod leading  to gate is missing or damaged. Gate is rusted  over 50% of its surface area. Gate is watertight  and works as designed. Gate moves up and down  easily and is watertight. Chain is in place  and works as designed. Gate is repaired  or replaced to meet design standards. Orifice Plate   Damaged or Missing Control device is  not working properly due to missing, out of place, or bent orifice  plate.Plate is in place  and works as designed. Obstructions Any trash, debris,  sediment, or vegetation blocking the plate.Plate is free of  all obstructions and works as designed. Overflow Pipe Obstructions Any trash or  debris blocking (or having the potential of blocking) the overflow pipe.Pipe is free of  all obstructions and works as designed. Access Opening See V-A.5 Maintenance Standards - Tanks and Vaults Catch Basin See V-A.7 Maintenance Standards - Catch Basins Table V-A.5: Maintenance Standards - Control Structures (continued) V-A.7 Maintenance Standards - Catch Basins Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is per- formed General   Trash & Debris    Trash or debris  which is located immediately in front of the catch basin opening or is  blocking inletting capacity of the basin by more than 10%. Trash or debris  (in the basin) that exceeds 60% of the sump depth as measured from the  bottom of basin to invert of the lowest pipe into or out of  the basin, but in  no case less than a minimum of 6 inches clearance from the debris surface  to the invert of the lowest pipe. Trash or debris in  any inlet or outlet pipe blocking more than 1/3 of its height. Dead animals or  vegetation that could generate odors that could cause complaints or dangerous  gases (e.g. methane). No Trash or debris  located immediately in front of  catch basin or on grate opening. No trash or debris  in the catch basin. Inlet and outlet  pipes free of trash or debris. No dead animals or  vegetation present within the  catch basin. Sediment Sediment (in the  basin) that exceeds 60% of the sump depth as measured from the bottom  of basin to invert of the lowest pipe into or out of the  basin, but in no  case less than a minimum of 6 inches clearance from the sediment surface to  the invert of the lowest pipe.No sediment in the  catch basin Structure Damage  to  Frame and/or Top Slab Top slab has holes  larger than 2 square inches or cracks wider than 1/4 inch. (Intent is to make  sure no material is running into basin). Frame not sitting  flush on top slab, i.e. separation of more than 3/4 inch of the frame from  the top slab. Frame not securely attached. Top slab is free  of holes and cracks. Frame is sitting  flush on the riser rings or top slab  and firmly attached. Fractures or  Cracks in  Basin Walls/ Bottom Maintenance person judges that structure is  unsound. Grout fillet has  separated or cracked wider than 1/2 inch and longer than 1 foot at the joint  of any inlet/outlet pipe or any evidence of soil particles  entering catch  basin through cracks. Basin replaced or  repaired to design standards. Pipe is regrouted  and secure at basin wall. Settlement/  Mis- alignment If failure of  basin has created a safety, function, or design problem. Basin replaced or  repaired to design standards. Vegetation Vegetation growing  across and blocking more than 10% of the basin opening. Vegetation growing  in inlet/outlet pipe joints that is more than 6 inches tall and less than  6 inches apart. No vegetation  blocking opening to basin. No vegetation or  root growth present. Contamination and  Pol-See V-A.2 Maintenance Standards - Detention Ponds No pollution  present. Table V-A.6: Maintenance Standards - Catch Basins 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1178 Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is per- formed lution Catch Basin Cover Cover Not in Place Cover is missing  or only partially in place. Any open catch basin requires maintenance.Cover/grate is in place, meets design standards,  and is secured. Locking Mechanism   Not Working Mechanism cannot be  opened by one maintenance person with proper tools. Bolts into frame have  less than 1/2 inch of thread.Mechanism opens  with proper tools. Cover Difficult to   Remove One maintenance  person cannot remove lid after applying normal lifting pressure. (Intent is keep  cover from sealing off access to maintenance.) Cover can be  removed by one maintenance per- son. Ladder Ladder Rungs  Unsafe Ladder is unsafe  due to missing rungs, not securely attached to basin wall, misalignment,  rust, cracks, or sharp edges.Ladder meets  design standards and allows main- tenance person safe access. Metal Grates (if applicable) Grate opening  Unsafe Grate with opening  wider than 7/8 inch.Grate opening  meets design standards. Trash and Debris Trash and debris  that is blocking more than 20% of grate surface inletting capacity.Grate free of  trash and debris. Damaged or  Missing.Grate missing or  broken member(s) of the grate.Grate is in place, meets the design standards, and  is installed and aligned with the flow path. Table V-A.6: Maintenance Standards - Catch Basins (continued) V-A.8 Maintenance Standards - Debris Barriers (e.g. Trash Racks) Maintenance Components Defect Condition When Maintenance is Needed Results Expected When Maintenance is Performed General Trash and Debris Trash or debris  that is plugging more than 20% of the openings in the barrier.Barrier cleared to  design flow capacity. Metal Damaged/ Missing  Bars Bars are bent out  of shape more than 3 inches. Bars are missing  or entire barrier missing. Bars are loose and  rust is causing 50% deterioration to any part of barrier. Bars in place with  no bends more than 3/4 inch. Bars in place  according to design. Barrier replaced  or repaired to design standards. Inlet/Outlet Pipe Debris barrier  missing or not attached to pipe Barrier firmly  attached to pipe Table V-A.7: Maintenance Standards - Debris Barriers (e.g. Trash Racks) V-A.9 Maintenance Standards - Energy Dissipators Maintenance Com- ponents Defect Conditions When Maintenance is Needed Results Expected When Maintenance is Performed External Rock Pad Missing or Moved  Rock Only one layer of  rock exists above native soil in area five square feet or larger, or any  exposure of native soil.Rock pad replaced  to design standards. Erosion Soil erosion in or  adjacent to rock pad.Rock pad replaced  to design standards. Dispersion Trench Pipe Plugged with  Sediment Accumulated  sediment that exceeds 20% of the design depth. Pipe  cleaned/flushed so that it matches  design. Table V-A.8: Maintenance Standards - Energy Dissipators 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1179 Maintenance Com- ponents Defect Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Not Discharging  Water Properly Visual evidence of water discharging at concentrated points along trench (normal condition is a "sheet flow" of water along trench).  Intent is to prevent erosion damage.Trench redesigned  or rebuilt to standards. Perforations  Plugged Over 1/2 of  perforations in pipe are plugged with debris and sediment.Perforated pipe  cleaned or replaced. Water Flowing out Top of "Distributor"  Catch Basin Maintenance person  observes or receives credible report of water flowing out during any storm  less than the design storm or is caus- ing or appears likely to cause damage. Energy dissipator rebuilt  or redesigned to  standards. Receiving Area  Oversaturated Water in receiving  area is causing or has potential of causing landslide problems.No danger of  landslides. Internal Manhole/Chamber   Worn or Damaged  Post, Baffles, or Side  of Chamber Structure  dissipating flow deteriorates to 1/2 of original size or any concentrated  worn spot exceeding one square foot, which would  make structure unsound.Structure replaced  to design standards. Other Defects See V-A.7 Maintenance Standards - Catch Basins Table V-A.8: Maintenance Standards - Energy Dissipators (continued) V-A.10 Maintenance Standards - Typical Biofiltration Swale Maintenance Component Defect or Problem Condition When Maintenance is Needed Recommended Maintenance to Correct Problem General Sediment  Accu- mulation on Grass Sediment depth  exceeds 2 inches.Remove sediment  deposits on grass treatment area of the biofiltration swale. When finished, swale  should be level from side to side and  drain freely toward outlet. There  should be no areas of standing water once inflow has ceased. Standing Water When water stands  in the swale between storms and does not  drain freely. Any of the  following may apply: remove sediment or trash blockages, improve grade from  head to foot of swale, remove clogged check  dams, add underdrains, or convert  to a wet biofiltration swale. Flow spreader Flow spreader  uneven or clogged so that flows are not uni- formly distributed through entire  swale width.Level the spreader  and clean so that flows are spread evenly over entire swale width. Constant Baseflow When small  quantities of water continually flow through the  swale, even when it has been  dry for weeks, and an eroded,  muddy channel has formed in the swale bottom. Add a low-flow  pea-gravel drain the length of the swale or by-pass the baseflow around the  swale. Poor Vegetation   Coverage When grass is  sparse or bare or eroded patches occur in more  than 10% of the swale bottom.  Determine why  grass growth is poor and correct that condition. Re-plant with plugs of grass  from the upper slope: plant in the swale bottom  at 8-inch intervals. Or  re-seed into loosened, fertile soil. Vegetation When the grass  becomes excessively tall (greater than 10- inches); when nuisance weeds and  other vegetation starts to  take over. Mow vegetation or  remove nuisance vegetation so that the flow is not impeded. Grass should be mowed to  a height of 3 to 4 inches.  Remove grass clippings.  Excessive Shading Grass growth is  poor because sunlight does not reach swale.If possible, trim  back over-hanging limbs and remove brushy vegetation on adjacent slopes. Inlet/Outlet Inlet/outlet areas  clogged with sediment and/or debris.Remove material so  that there is no clogging or blockage in the inlet and outlet area. Trash and Debris   Accumulation Trash and debris  accumulated in the bio-swale.Remove trash and  debris from biofiltration swale. Erosion/Scouring Eroded or scoured  swale bottom due to flow channelization, or  higher flows. For ruts or bare  areas less than 12 inches wide, repair the damaged area by filling with  crushed gravel. If bare areas are large, generally  greater than 12 inches  wide, the swale should be re-graded and re-seeded. For smaller bare areas,  overseed when bare spots are evident,  or take plugs of grass from the upper  slope and plant in the swale bottom at 8-inch intervals. Table V-A.9: Maintenance Standards - Typical Biofiltration Swale 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1180 V-A.19 Maintenance Standards - Coalescing Plate (CP) Oil/Water Separators Maintenance Component Defect Condition When Maintenance is Needed Results Expected When Maintenance is Performed General Monitoring Inspection of  discharge water for obvious signs of poor water quality.Effluent discharge  from vault should be clear with no thick visible sheen. Sediment  Accumulation Sediment depth in  bottom of vault exceeds 6 inches in depth and/or visible signs of sediment  on  plates. No sediment  deposits on vault bottom and plate media, which would impede  flow through the  vault and reduce separation efficiency. Trash and Debris  Accumulation Trash and debris  accumulated in vault, or pipe inlet/outlet, floatables and non-floatables.Trash and debris  removed from vault and inlet/outlet piping. Oil Accumulation Oil accumulation  that exceeds 1 inch at the water surface. Oil is extracted  from vault using vactoring methods. Coalescing plates are  cleaned by  thoroughly rinsing and flushing. Should be no visible oil depth on  water. Damaged Coalescing  Plates Plate media  broken, deformed, cracked and/or showing signs of failure.A portion of the  media pack or the entire plate pack is replaced depending on  severity of  failure. Damaged Pipes Inlet or outlet  piping damaged or broken and in need of repair.Pipe repaired and  or replaced. Baffles Baffles corroding,  cracking, warping and/or showing signs of failure as determined by  main- tenance/inspection person.Baffles repaired  or replaced to specifications. Vault Structure  Damage - Includes Cracks in  Walls, Bottom, Damage to Frame and/or Top  Slab Cracks wider than  0.5 inch or evidence of soil particles entering the structure through the   cracks, or maintenance/inspection personnel determine that the vault is not  structurally  sound. Cracks wider than  0.5 inch at the joint of any inlet/outlet pipe or evidence of soil particles   entering through the cracks. Vault replaced or  repairs made so that vault meets design specifications and is  structurally  sound. Vault repaired so  that no cracks exist wider than 0.25 inch at the joint of the  inlet/outlet  pipe. Access Ladder  Damaged Ladder is corroded  or deteriorated, not functioning properly, not securely attached to struc- ture  wall, missing rungs, cracks, and misaligned. Ladder replaced or  repaired and meets specifications, and is safe to use as  determined by  inspection personnel. Table V-A.18: Maintenance Standards - Coalescing Plate (CP) Oil/Water Separators V-A.20 Maintenance Standards - Catch Basin Inserts Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is Performed General Sediment  Accumulation When sediment  forms a cap over the insert media of the insert and/or unit.No sediment cap on  the insert media and its unit. Trash and Debris  Accumulation Trash and debris  accumulates on insert unit creating a blockage/restriction.Trash and debris  removed from insert unit. Runoff freely flows into catch basin. Media Insert Not  Removing Oil Effluent water  from media insert has a visible sheen.Effluent water  from media insert is free of oils and has no visible sheen. Media Insert Water  Saturated Catch basin insert  is saturated with water and no longer has the capacity to absorb.Remove and replace  media insert Media Insert-Oil  Saturated Media oil saturated  due to petroleum spill that drains into catch basin.Remove and replace  media insert. Media Insert Use  Beyond  Product Life Media has been  used beyond the typical average life of media insert product.Remove and replace  media at regular intervals, depending on insert product. Table V-A.19: Maintenance Standards - Catch Basin Inserts 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1188 Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Flow  Spreader  Flow  spreader is uneven or clogged so that  flows are not uniformly distributed  over entire  filter width.  Level  the spreader and clean so that flows are spread evenly over entire filter  width. Table V-A.21: Maintenance Standards - Compost-Amended Vegetated Filter Strips (CAVFS) (continued) V-A.23 Maintenance Standards - Bioretention Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards)Action Needed (Procedures) Inspection Routine Main- tenance Facility Footprint Earthen side slopes  and berms B, S  Erosion (gullies/ rills) greater than 2 inches deep  around  inlets, outlet, and alongside slopes  l Eliminate cause of erosion and stabilize damaged area (regrade, rock,  vegetation, erosion control matting)       l For deep channels or cuts (over 3  inches in ponding depth), temporary erosion control measures should be put in   place until permanent repairs can be made.      l Properly designed, constructed and  established facilities with appropriate flow velocities should not have  erosion  problems except perhaps in extreme events. If erosion problems  persist, the following should be reassessed: (1)  flow volumes from  contributing areas and bioretention facility sizing; (2) flow velocities and  gradients within the facil- ity; and (3) flow dissipation and erosion  protection strategies at the facility inlet. A  Erosion of sides causes slope to become a hazard Take actions to eliminate the hazard and stabilize slopes A, S  Settlement greater than 3 inches (relative to undis- turbed  sections of berm)Restore to design height A, S  Downstream face of berm wet, seeps or leaks evid- ent Plug any holes and compact berm (may require consultation with  engineer, particularly for larger berms) A  Any evidence of rodent holes or water piping in  berm  l Eradicate rodents (see "Pest  control")       l Fill holes and compact (may  require consultation with engineer, particularly for larger berms) Concrete sidewalls A  Cracks or failure of concrete sidewalls  l Repair/ seal cracks      l Replace if repair is insufficient Rockery sidewalls A  Rockery side walls are insecure Stabilize rockery sidewalls (may require consultation with  engineer, particularly for walls 4 feet or greater in height) Facility area   All maintenance vis- its (at least bian- nually) Trash and debris present Clean out trash and debris Facility bottom area A, S   Accumulated sediment to extent that infiltration rate  is  reduced (see "Ponded water") or surface storage  capacity significantly  impacted  l Remove excess sediment       l Replace any vegetation damaged or  destroyed by sediment accumulation and removal  l Mulch newly planted  vegetation      l Identify and control the sediment  source (if feasible)     Table V-A.22: Maintenance Standards - Bioretention 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1190 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards)Action Needed (Procedures) Inspection Routine Main- tenance  l If accumulated sediment is  recurrent, consider adding presettlement or installing berms to create a  forebay at the  inlet  During/after fall leaf  drop Accumulated leaves in facility Remove leaves if there is a risk to clogging outlet structure  or water flow is impeded Low permeability  check dams  and weirs A, S   Sediment, vegetation, or debris accumulated at or  blocking (or  having the potential to block) check  dam, flow control weir or orifice Clear the blockage A, S  Erosion and/or undercutting present Repair and take preventative measures to prevent future erosion  and/or undercutting A  Grade board or top of weir damaged or not level Restore to level position Ponded water B, S   Excessive ponding water: Water overflows during  storms smaller  than the design event or ponded  water remains in the basin 48 hours or longer  after  the end of a storm. Determine  cause and resolve in the following order:       1. Confirm leaf or debris buildup in  the bottom of the facility is not impeding infiltration. If necessary, remove  leaf lit- ter/debris.       2. Ensure that underdrain (if  present) is not clogged. If necessary, clear underdrain.  3. Check for other water inputs  (e.g., groundwater, illicit connections).   4. Verify that the facility is sized  appropriately for the contributing area. Confirm that the contributing area  has not  increased.     If steps #1-4 do not solve the problem, the bioretention soil is likely  clogged by sediment accumulation at  the surface or has become overly  compacted. Dig a small hole to observe soil profile and identify compaction  depth  or clogging front to help determine the soil depth to be removed or  otherwise rehabilitated (e.g., tilled). Consultation  with an engineer is  recommended. Bioretention soil mix As needed   Bioretention soil mix protection is needed when per- forming  maintenance requiring entrance into the  facility footprint  l Minimize all loading in the facility  footprint (foot traffic and other loads) to the degree feasible in order to  prevent  compaction of bioretention soils.      l Never drive equipment or apply  heavy loads in facility footprint.      l Because the risk of compaction is  higher during saturated soil conditions, any type of loading in the cell  (including  foot traffic) should be minimized during wet conditions.   l Consider measures to distribute loading if heavy foot traffic is required  or equipment must be placed in facility. As  an example, boards may be placed  across soil to distribute loads and minimize compaction.     l If compaction occurs, soil must be loosened or otherwise rehabilitated to  original design state. Inlets/Outlets/Pipes Splash block inlet A  Water is not being directed properly to the facility  and away  from the inlet structure Reconfigure/ repair blocks to direct water to facility and away  from structure Curb cut inlet/outlet M during the wet  season and  before severe  storm is fore- casted Weekly during fall  leaf drop Accumulated leaves at curb cuts Clear leaves (particularly important for key inlets and low  points along long, linear facilities) Table V-A.22: Maintenance Standards - Bioretention (continued) 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1191 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards)Action Needed (Procedures) Inspection Routine Main- tenance Pipe inlet/outlet A  Pipe is damaged Repair/ replace W  Pipe is clogged Remove roots or debris A, S  Sediment, debris, trash, or mulch reducing capacity  of  inlet/outlet  l Clear the blockage  l Identify the source of the  blockage and take actions to prevent future blockages  Weekly during fall  leaf drop Accumulated leaves at inlets/outlets Clear leaves (particularly important for key inlets and low  points along long, linear facilities)  A Maintain access for inspections  l Clear vegetation (transplant vegetation  when possible) within 1 foot of inlets and outlets, maintain access  pathways  l Consultation with a landscape  architect is recommended for removal, transplant, or substitution of plants Erosion control at inlet A  Concentrated flows are causing erosion Maintain a cover of rock or cobbles or other erosion protection  measure (e.g., matting) to protect the ground where con- centrated water enters  the facility (e.g., a pipe, curb cut or swale) Trash rack S  Trash or other debris present on trash rack Remove/dispose A  Bar screen damaged or missing Repair/replace Overflow A, S  Capacity reduced by sediment or debris Remove sediment or debris/dispose Underdrain pipe Clean pipe as  needed Clean orifice at  least biannually  (may need more fre- quent  cleaning     dur- ing wet season)  l Plant roots, sediment or debris reducing  capa- city of underdrain  l Prolonged surface ponding (see "Ponded  water"                               l Jet clean or rotary cut debris/roots from  underdrain(s)  l If underdrains are equipped with a  flow restrictor (e.g., orifice) to attenuate flows, the orifice must be cleaned  reg- ularly. Vegetation Facility bottom area  and upland slope   vegetation Fall and Spring   Vegetation survival rate falls below 75% within first  two years  of establishment (unless project O&M  manual or record drawing stipulates  more or less  than 75% survival rate).  l Determine cause of poor vegetation growth  and correct condition  l Replant as necessary to obtain 75%  survival rate or greater. Refer to original planting plan, or approved  jur- isdictional species list for appropriate plant replacements (See Appendix  3 - Bioretention Plant List, in the LID Tech- nical Guidance Manual for Puget Sound, (Hinman and Wulkan, 2012)).  l Confirm that plant selection is  appropriate for site growing conditions  l Consultation with a landscape  architect is recommended for removal, transplant, or substitution of plants Vegetation (general)As needed  Presence of diseased plants and plant material  l Remove any diseased plants or plant parts  and dispose of in an approved location (e.g., commercial landfill) to  avoid  risk of spreading the disease to other plants  l Disinfect gardening tools after  pruning to prevent the spread of disease  l See the Pacific Northwest Plant Disease Management Handbook (Pscheidt and Ocamb, 2016) for information on  disease recognition and for  additional resources  l Replant as necessary according to  recommendations provided for "facility bottom area and upland slope  veget- ation". Trees and  shrubs  All pruning seasons      (timing varies by Pruning as needed  l Prune trees and shrubs in a manner  appropriate for each species. Pruning should be performed by landscape  pro- fessionals familiar with proper pruning techniques Table V-A.22: Maintenance Standards - Bioretention (continued) 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1192 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards)Action Needed (Procedures) Inspection Routine Main- tenance species) l All pruning of mature trees should  be performed by or under the direct guidance of an ISA certified arborist A  Large trees and shrubs interfere with operation of  the facility  or access for maintenance  l Prune trees and shrubs using most current  ANSI A300 standards and ISA BMPs.  l Remove trees and shrubs, if  necessary. Fall and Spring  Standing dead vegetation is present  l Remove standing dead vegetation  l Replace dead vegetation within 30  days of reported dead and dying plants (as practical depending on  weather- /planting season)  l If vegetation replacement is not  feasible within 30 days, and absence of vegetation may result in erosion  problems,  temporary erosion control measures should be put in place  immediately.  l Determine cause of dead vegetation  and address issue, if possible  l If specific plants have a high  mortality rate, assess the cause and replace with appropriate species.  Consultation  with a landscape architect is recommended. Fall and Spring  Planting beneath mature trees  l When working around and below mature trees,  follow the most current ANSI A300 standards and ISA BMPs to the  extent  practicable (e.g., take care to minimize any damage to tree roots and avoid  compaction of soil).  l Planting of small shrubs or  groundcovers beneath mature trees may be desirable in some cases; such  plantings  should use mainly plants that come as bulbs, bare root or in 4-inch  pots; plants should be in no larger than 1-gallon  containers. Fall and Spring  Presence of or need for stakes and guys (tree  growth,  maturation, and support needs)  l Verify location of facility liners and  underdrain (if any) prior to stake installation in order to prevent liner  puncture or  pipe damage  l Monitor tree support systems:  Repair and adjust as needed to provide support and prevent damage to  tree.  l Remove tree supports (stakes,  guys, etc.) after one growing season or maximum of 1 year.     l Backfill stake holes after  removal. Trees and shrubs adja- cent to vehicle travel  areas (or areas where   visibility needs to be  maintained) A  Vegetation causes some visibility (line of sight) or  driver  safety issues  l Maintain appropriate height for sight  clearance  l When continued, regular pruning  (more than one time/ growing season) is required to maintain visual sight  lines for  safety or clearance along a walk or drive, consider relocating the  plant to a more appropriate location.  l Remove or transplant if continual  safety hazard  l Consultation with a landscape  architect is recommended for removal, transplant, or substitution of plants Flowering plants  A Dead or spent flowers present Remove spent flowers (deadhead) Perennials  Fall Spent plants Cut back dying or dead and fallen foliage and stems Emergent vegetation  Spring Vegetation compromises conveyance Hand rake sedges and rushes with a small  rake or fingers to remove dead foliage before new growth emerges in spring or   earlier only if the foliage is blocking water flow (sedges and rushes do not  respond well to pruning) Ornamental grasses      (perennial) Winter and Spring Dead material from previous year's growing cycle or  dead  collapsed foliage  l Leave dry foliage for winter interest  l Hand rake with a small rake or  fingers to remove dead foliage back to within several inches from the soil  before new  growth emerges in spring or earlier if the foliage collapses and  is blocking water flow Table V-A.22: Maintenance Standards - Bioretention (continued) 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1193 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards)Action Needed (Procedures) Inspection Routine Main- tenance Ornamental grasses      (evergreen) Fall and Spring Dead growth present in spring  l Hand rake with a small rake or fingers to  remove dead growth before new growth emerges in spring  l Clean, rake, and comb grasses when  they become too tall   l Cut back to ground or thin every  2-3 years as needed Noxious weeds   M     (March - Octo- ber, preceding  seed dispersal) Listed noxious vegetation is present (refer to current  county  noxious weed list)  l By law, class A & B noxious weeds must  be removed, bagged and disposed as garbage immediately  l Reasonable attempts must be made  to remove and dispose of class C noxious weeds  l It is strongly encouraged that  herbicides and pesticides not be used in order to protect water quality; use  of herb- icides and pesticides may be prohibited in some jurisdictions  l Apply mulch after weed removal (see "Mulch") Weeds   M     (March - Octo- ber, preceding  seed dispersal) Weeds are present  l Remove weeds with their roots manually with  pincer-type weeding tools, flame weeders, or hot water weeders as   appropriate  l Follow IPM protocols for weed management (see "Additional Maintenance Resources" section for more information  on IPM protocols) Excessive vegetation   Once in early to  mid- May and once  in early- to mid-  September Low-lying vegetation growing beyond facility edge  onto  sidewalks, paths, or street edge poses ped- estrian safety hazard or may clog  adjacent per- meable pavement surfaces due to associated leaf  litter, mulch,  and soil  l Edge or trim groundcovers and shrubs at  facility edge  l Avoid mechanical blade-type edger and do not use edger or trimmer within 2 feet of tree trunks  l While some clippings can be left in the facility to replenish organic material in the soil, excessive leaf litter can cause  surface soil clogging As needed   Excessive vegetation density inhibits stormwater  flow beyond design ponding or becomes a hazard  for pedestrian and vehicular circulation and safety  l Determine whether pruning or other routine maintenance is adequate to maintain proper plant density and aes- thetics  l Determine if planting type should be replaced to avoid ongoing maintenance issues (an aggressive grower under  perfect growing conditions should be transplanted to a location where it will not impact flow)  l Remove plants that are weak, broken or not true to form; replace in-kind  l Thin grass or plants impacting  facility function without leaving visual holes or bare soil areas      l Consultation with a landscape  architect is recommended for removal, transplant, or substitution of plants As needed  Vegetation blocking curb cuts, causing excessive  sediment  buildup and flow bypass Remove vegetation and sediment buildup Mulch Mulch  Following weeding Bare spots (without mulch cover) are present or  mulch depth  less than 2 inches  l Supplement mulch with hand tools to a depth  of 2 to 3 inches   l Replenish mulch per O&M  manual. Often coarse compost is used in the bottom of the facility and arborist  wood  chips are used on side slopes and rim (above typical water levels)     l Keep all mulch away from woody  stems Watering Irrigation system (if  any) Based on man- ufacturer's instruc-Irrigation system present Follow manufacturer's instructions for  O&M Table V-A.22: Maintenance Standards - Bioretention (continued) 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1194 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards)Action Needed (Procedures) Inspection Routine Main- tenance tions A  Sprinklers or drip irrigation not directed/located to  properly  water plants Redirect sprinklers or move drip irrigation  to desired areas Summer watering     (first  year)  Once every 1-2  weeks or as  needed during pro- longed dry periods Trees, shrubs and groundcovers in first year of  establishment  period  l 10 to 15 gallons per tree      l 3 to 5 gallons per shrub      l 2 gallons water per square foot for groundcover areas      l Water deeply, but infrequently, so  that the top 6 to 12 inches of the root zone is moist      l Use soaker hoses or spot water with a shower type wand when irrigation system is not present  o Pulse water to enhance soil absorption, when feasible      o Pre-moisten soil to break surface tension of dry or hydrophobic  soils/mulch, followed by several more  passes. With this method , each pass  increases soil absorption and allows more water to infiltrate prior to  run- off       l Add a tree bag or slow-release  watering device (e.g., bucket with a perforated bottom) for watering newly  installed  trees when irrigation system is not present Summer watering  (second and third  years)   Once every 2-4  weeks or as  needed during pro- longed dry periods Trees, shrubs and groundcovers in second or third  year of  establishment period  l 10 to 15 gallons per tree      l 3 to 5 gallons per shrub      l 2 gallons water per square foot for groundcover areas      l Water deeply, but infrequently, so  that the top 6 to 12 inches of the root zone is moist       l Use soaker hoses or spot water with a shower type wand when irrigation system is not present  o Pulse water to enhance soil  absorption, when feasible       o Pre-moisten soil to break surface  tension of dry or hydrophobic soils/mulch, followed by several more  passes.  With this method , each pass increases soil absorption and allows more water  to infiltrate prior to run- off Summer watering      (after establishment) As needed Established vegetation (after 3 years)  l Plants are typically selected to be drought  tolerant and not require regular watering after establishment; however,  trees  may take up to 5 years of watering to become fully established      l Identify trigger mechanisms for  drought-stress (e.g., leaf wilt, leaf senescence, etc.) of different species  and water  immediately after initial signs of stress appear      l Water during drought conditions or  more often if necessary to maintain plant cover Pest Control Mosquitoes B, S  Standing water remains for more than 3 days after  the end of a  storm  l Identify the cause of the standing water  and take appropriate actions to address the problem (see "Ponded  water")       l To facilitate maintenance,  manually remove standing water and direct to the storm drainage system (if  runoff is from  non pollution-generating surfaces) or sanitary sewer system  (if runoff is from pollution-generating surfaces) after  getting approval from  sanitary sewer authority.       l Use of pesticides or Bacillus thuringiensis israelensis   (Bti) may be considered only as a temporary measure while  Table V-A.22: Maintenance Standards - Bioretention (continued) 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1195 Maintenance Com- ponent Recommended Frequency a Condition when Maintenance is Needed (Stand- ards)Action Needed (Procedures) Inspection Routine Main- tenance addressing the  standing water cause. If overflow to a surface water will occur within 2  weeks after pesticide use,  apply for coverage under the Aquatic Mosquito  Control NPDES General Permit. Nuisance animals As needed  Nuisance animals causing erosion, damaging  plants, or  depositing large volumes of feces  l Reduce site conditions that attract  nuisance species where possible (e.g., plant shrubs and tall grasses to  reduce  open areas for geese, etc.)        l Place predator decoys       l Follow IPM protocols for specific nuisance animal issues (see "Additional Maintenance Resources" section for  more information on IPM protocols)        l Remove pet waste regularly        l For public and right-of-way sites  consider adding garbage cans with dog bags for picking up pet waste. Insect pests Every site visit  associated with  vegetation man- agement  Signs of pests, such as wilting leaves, chewed  leaves and bark,  spotting or other indicators  l Reduce hiding places for pests by removing  diseased and dead plants       l For infestations, follow IPM protocols (see "Additional Maintenance Resources" section for more information on  IPM protocols) Note that the inspection and routine maintenance frequencies listed above are recommended by Ecology. They do not supersede or replace the municipal stormwater permit requirements for inspection frequency required of municipal stormwater  permittees for "stormwater treatment and flow control BMPs/facilities". a Frequency: A = Annually; B = Biannually (twice per year); M = Monthly;  W = At least one visit should occur during the wet season (for debris/clog  related maintenance, this inspection/maintenance visit should occur in the  early fall, after decidu- ous trees have lost their leaves); S = Perform  inspections after major storm events (24-hour storm event with a 10-year or  greater recurrence interval). IPM - Integrated Pest Management ISA - International Society of Arboriculture Table V-A.22: Maintenance Standards - Bioretention (continued) V-A.24 Maintenance Standards - Permeable Pavement Component Recommended Frequency a Condition when Maintenance is Needed (Standards)Action Needed (Procedures) Inspection Routine Maintenance Surface/Wearing Course Permeable     Pave- ments, all A, S  Runoff from adjacent pervious areas deposits  soil, mulch or  sediment on paving  l Clean deposited soil or other materials  from permeable pavement or other adjacent surfacing     l Check if surface elevation of  planted area is too high, or slopes towards pavement, and can be regraded   (prior to regrading, protect permeable pavement by covering with temporary  plastic and secure covering in  place)      l Mulch and/or plant all exposed  soils that may erode to pavement surface Porous asphalt or  pervious  concrete  A or B None  (routine maintenance) Clean  surface debris from pavement surface using one or a combination of the  following methods:      l Remove sediment, debris, trash,  vegetation, and other debris deposited onto pavement (rakes and leaf  blowers can  be used for removing leaves)      Table V-A.23: Maintenance Standards - Permeable Pavement 2024 Stormwater Management Manual for Western Washington Volume V -Appendix A -Page 1196