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Yelm HS Storm Drainage RPT_01-03-2023
January 3, 2023 Prepared for: Yelm High School 1315 Yelm Ave W Yelm, WA 98597 Prepared by: Ben Enfield, PE Whitney Dunlap, PE As a sub-consultant to RWD Landscape Architects PRELIMINARY DRAINAGE REPORT Yelm HS Soccer Field Conversion and Tennis Court Reconstruction Yelm, WA Project #: 10182200114 Consulting Engineers 612 Woodland Square Loop SE, Suite 100 Lacey, WA 98503 (360) 292-7230 (360) 292-7231 FAX 1 | P a g e ENGINEER OF RECORD CERTIFICATION This Drainage Report for Yelm High School Soccer Field Conversion and Tennis Court Reconstruction has been prepared by or under the supervision of the engineer below and meets the standard of care and expertise which is usual and customary in this community for professional engineers. It is understood that the City of Yelm does not and will not assume liability for the sufficiency, suitability, or performance of facilities included in this report. 2 | P a g e 3 | P a g e CONTENTS 1 Project Overview ................................................................................................................. 5 1.1 Project Location & Parcel Information .......................................................................... 5 1.2 Project Summary ......................................................................................................... 5 1.3 Minimum Requirements ............................................................................................... 6 2 Existing Conditions Summary ............................................................................................. 7 2.1 Existing Conditions ...................................................................................................... 7 2.2 Critical Areas ............................................................................................................... 7 2.3 Existing Soil Conditions ............................................................................................... 7 3 Off-Site Analysis Report ...................................................................................................... 8 4 Stormwater Control Plan ..................................................................................................... 8 4.1 Existing Site Hydrology ................................................................................................ 8 4.2 Developed Site Hydrology ............................................................................................ 8 4.3 Performance Standards and Goals .............................................................................. 8 4.4 Flow Control System .................................................................................................... 8 4.5 Water Quality System .................................................................................................. 9 5 Construction Stormwater Pollution Prevention Plan ............................................................ 9 6 Special Reports and Studies ............................................................................................... 9 7 Other Permits ...................................................................................................................... 9 8 Operations and Maintenance .............................................................................................. 9 TABLES Table 1: Existing Areas .............................................................................................................. 5 Table 2: Proposed Areas ........................................................................................................... 6 Table 3: Infiltration Facility Summary ......................................................................................... 9 APPENDICES Appendix A – Basin Map Appendix B – Stormwater Calculations Appendix C – CSWPPP Appendix D – Geotechnical Report 4 | P a g e 5 | P a g e 1 Project Overview 1.1 Project Location & Parcel Information Site Address: 1315 Yelm Ave W Parcel Number: 21724210500 Property Owner: Yelm School District #2 Total Parcel Area: 36.6 Acres Abbreviated Legal: Section 24, Township 17, Range 1E 1.2 Project Summary The proposed site improvements are located at the northwest portion of the Yelm High School campus. The project proposes to resurface six existing tennis courts, convert a grass field to a synthetic turf field, replace asphalt sidewalks and install associated drainage improvements. Elevations of the area range from approximately 346 to 342 generally sloping from east to west. Of the entire 36.6-acre property, the proposed redevelopment will disturb approximately 151,120 square feet (3.47 acres). After completion of this project, 60 percent of the site will be pervious with the remaining 40 percent impervious. Table 1 summarizes existing on-site areas that will be disturbed with this redevelopment. Table 2 provides a summary of proposed on-site improvement areas. Stormwater runoff from the proposed project will be collected through trench drains, catch basins and underdrains where it will be routed to infiltration galleries proposed under the resurfaced synthetic turf soccer field. Under existing conditions, catch basins located on the west side of the field collect stormwater runoff where it is infiltrated onsite. Table 1: Existing Areas Cover Surface Type Area (sf) Sidewalk NPGIS* 14,330 Tennis Courts NPGIS* 39,800 Total Impervious 54,130 Grass Field NPGPS 95,030 Other Landscape NPGPS 1,960 Total Disturbed Area 151,120 (3.47 acres) 6 | P a g e Table 2: Proposed Areas Cover Surface Type Area (sf) Sidewalk NPGIS 18,820 Tennis Courts NPGIS 42,000 Total Impervious 60,820 Synthetic Turf Field NPGPS 90,300 Total Disturbed Area 151,120 (3.47 acres) 1.3 Minimum Requirements This project requires compliance will all minimum requirements. Minimum Requirement #1: Stormwater Site Planning This report meets the requirements of Stormwater Site Planning per the 2019 Stormwater Management Manual for Western Washington. Minimum Requirement #2: Construction Stormwater Pollution Prevention Plan (CSWPPP) A CSWPPP is provided within Appendix C of this report. Minimum Requirement #3: Source Control of Pollution Source Control BMPs applicable to all sites: · S410 BMPs for Correcting Illicit Discharges to Storm Drains · S453 BMPs for Formation of a Pollution Prevention Team · S454 BMPs for Preventive Maintenance / Good Housekeeping · S455 BMPs for Spill Prevention and Cleanup · S456 BMPs for Employee Training · S457 BMPS for Inspections · S458 BMPs for Record Keeping Other Source Control BMPs applicable to this specific site: · S417 BMPs for Maintenance of Stormwater Drainage and Treatment Systems Minimum Requirement #4: Preservation of Natural Drainage Systems and Outfalls The natural drainage pattern of the site will be maintained through continued use of on-site infiltration. Stormwater runoff from the project site will be collected and infiltrated through rock conveyance galleries located under the soccer field. Minimum Requirement #5: On-Site Stormwater Management This project meets the LID performance standard by providing full on-site infiltration of stormwater runoff therefore complying with this core requirement. Minimum Requirement #6: Runoff Treatment No runoff treatment is required or provided. All proposed improvements are non-pollution generating. 7 | P a g e Minimum Requirement #7: Flow Control Full infiltration of runoff from pervious and impervious surfaces is being provided onsite for this project meeting minimum requirements for flow control. Minimum Requirement #8: Wetlands Protection There are no wetlands on or adjacent to the project site and the project does not discharge into a wetland directly or indirectly through a conveyance system, therefore this minimum requirement does not apply. Minimum Requirement #9: Operations & Maintenance An Operations and Maintenance manual will be included within the final Stormwater Site Plan for permit submittal. 2 Existing Conditions Summary 2.1 Existing Conditions The existing project site contains six tennis courts, walkways, and a grass field. Under existing conditions stormwater runoff from the tennis courts is directed into existing catch basins and infiltrates on site. The grass field also currently infiltrates all stormwater. 2.2 Critical Areas Critical areas mapped and noted to be nearby the project are as follows: Streams Thompson Creek, a Class 4 stream is located approximately 1,000 feet from the project site. Flood Zone Flood zone A for Thompson creek is approximately 1,000 feet from the project site and approximately 15 vertical feet below. Critical Aquifer Recharge Area Category 1 CARA is mapped within the project site. No wetlands, watershed protections areas, high groundwater areas, fuel tanks, wells, septic systems or landfills were found or are known that would affect this project. 2.3 Existing Soil Conditions The site is mapped as Spanaway gravelly sandy loam, 0 to 3% slopes as well as Spanaway stony sandy loam, 0 to 3% slopes by the USDA Natural Resource Conservation Service. The geotechnical engineer encountered topsoil of approximately 6” underlain with recessional outwash consistent with the mapped soils. 8 | P a g e 3 Off-Site Analysis Report All runoff generated on the project site is proposed to be infiltrated on-site. There are no significant areas of offsite land that contribute runoff to the project site. A downstream analysis is not required for this site. 4 Stormwater Control Plan 4.1 Existing Site Hydrology Runoff in the tennis court and soccer field area currently sheet flows and infiltrates in the immediate vicinity. 4.2 Developed Site Hydrology The site improvements maintain the existing use and function in place. Runoff will be collected and infiltrated in the field. An infiltration trench as well as rock section underlying the proposed turf field is proposed to infiltrate all runoff from the project site. 4.3 Performance Standards and Goals This project will meet the LID performance standard for flow control through full infiltration. 4.4 Flow Control System Runoff from the project site is directed to two separate infiltration facilities for full infiltration. The West infiltration facility is an infiltration trench that receives runoff from the west of the project including the tennis courts and walkway on the west side of the field. The East infiltration facility is 6 inches of rock under the entirety of the turf field. Areas tributary to the east infiltration facility include the soccer field and eastern walkways. The basin map located in Appendix A of the report shows the basins and are breakdowns to each facility. The stormwater calculations for facility sizing can be found in Appendix B of this report. Based on the geotechnical report, infiltration rates differ across the site. There were four test pits excavated at each of the four corners of the existing grass field. The western facility is proposed where Test Pits 1 and 4 are located, which both were found to have an infiltration rate of 20 in/hr at a bottom facility depth of at least of 4.5’ deep. The infiltrate rate in the upper layer of the test pits was found to have a reduced infiltration rate. The average of the infiltration rates in the four test pits for a depth of 0.5’ was found to be 4.85 in/hr and was utilized for design calculations of the rock section under the turf field. The full geotechnical report can be found in Appendix D of this report that shows all infiltration rates at corresponding depths. 9 | P a g e Table 3: Infiltration Facility Summary West Facility East Facility Pervious Contributing Area (ac) 0.00 2.07 Impervious Contributing Area (ac) 1.19 0.21 Total Basin Area (ac) 1.19 2.28 Infiltration rate (in/hr) 20 15.7 Facility Size (L’ x W’ x D’) 378’ x 2.5’ x 4.17’ 400’ x 225’ x 0.5’* *Facility size is approximated for calculations based on field area of 90,000 SF. Actual field area is 90,300 SF. 4.5 Water Quality System No water quality is proposed for this project as it does not meet thresholds for treatment. 5 Construction Stormwater Pollution Prevention Plan A SWPPP has been completed and included as Appendix C of this report. 6 Special Reports and Studies A geotechnical engineering report has been conducted for this site and is included in Appendix D of this report. 7 Other Permits Associated building permits for the fence may be required. Owner to confirm with City. 8 Operations and Maintenance An operations and maintenance manual will be provided for the site with the final drainage report. APPENDIX A Basin Map 343.22 343.12 ME HP 345.02ME 343.12 343.02 343.02 343.23 343.12 343.72 343.22 .5% .83%1.0% 343.12 343.22 1.0% 344.00 344.00 343.72 343.72 .5% 344.70 343.12 TW: 344.72 BW 342.72 343.12 343.121.0%343.31 343.54 343.28 343.25 1.5%1.0%344.00 343.22 ME343.55 2C2.11C2.1PERMITTING SUBMITTALA B C D E F G H 1 2 3 4 5 6 Yelm High School Yelm WA Yelm HS Soccer Field Conversion and Tennis Courts Reconstruction R Call 811 two business days before you dig 4405 7th Ave. SE, Suite 203 Lacey, WA 98503 360.456.3813 bob@rwdroll.com 0 SCALE: 1"=30' 15'30'45'60' GRADING PLAN C2.0 PROPOSED INTERMEDIATE CONTOUR PROPOSED INDEX CONTOUR GRADE BREAK DIRECTION OF SLOPE FINISH GRADE ELEVATION EXISTING GRADE RIM ELEVATION MEET EXISTING TOP OF WALL BOTTOM OF WALL TOP OF RAMP BOTTOM OF RAMP LIMIT OF WORK XXX XXX XXX.XX EX RE GRADING LEGEND ME TW BW TR BR EAST INFILTRATION BASIN Turf field (pervious) = 90,300 sf = 2.07 ac Walkways (impervious) = 9,200 sf = 0.21 ac Basin Total = 99,500 sf = 2.28 ac WEST INFILTRATION BASIN Turf field (pervious) = 0 sf = 0.00 ac Tennis court & walkways (impervious) = 51,620 sf = 1.19 ac Basin Total = 51,620 sf = 1.19 ac TOTAL BASIN Turf field (pervious) = 90,300 sf = 2.07 ac Tennis court & walkways (impervious) = 60,820 sf = 1.40 ac Basin Total = 151,120 sf = 3.47 ac WEST INFILTRATION TRENCH 378' (L) X 2'-6" (W) X 4'-2" (D) EAST INFILTRATION 6" ROCK UNDER 90,000 SF OF TURF FIELD BASIN MAP EX 1.0 APPENDIX B Stormwater Calculations WWHM2012 PROJECT REPORT Yelm HS Soccer Field Conversion & Tennis Court Reconstruction Flow Control Sizing Yelm HS Infiltration 1/3/2023 2:18:25 PM Page 2 General Model Information Project Name:Yelm HS Infiltration Site Name:Yelm HS Site Address:1315 W Yelm Ave City:Yelm Report Date:1/3/2023 Gage:Eaton Creek Data Start:1955/10/01 Data End:2011/09/30 Timestep:15 Minute Precip Scale:0.857 Version Date:2021/08/18 Version:4.2.18 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year Yelm HS Infiltration 1/3/2023 2:18:25 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre A B, Forest, Flat 3.47 Pervious Total 3.47 Impervious Land Use acre Impervious Total 0 Basin Total 3.47 Element Flows To: Surface Interflow Groundwater Yelm HS Infiltration 1/3/2023 2:18:25 PM Page 4 Mitigated Land Use WEST BASIN Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre SIDEWALKS FLAT 1.19 Impervious Total 1.19 Basin Total 1.19 Element Flows To: Surface Interflow Groundwater WEST TRENCH WEST TRENCH Yelm HS Infiltration 1/3/2023 2:18:25 PM Page 5 EAST BASIN Bypass:No GroundWater:No Pervious Land Use acre A B, Lawn, Flat 2.07 Pervious Total 2.07 Impervious Land Use acre SIDEWALKS FLAT 0.21 Impervious Total 0.21 Basin Total 2.28 Element Flows To: Surface Interflow Groundwater EAST TRENCH EAST TRENCH Yelm HS Infiltration 1/3/2023 2:18:25 PM Page 6 Routing Elements Predeveloped Routing Yelm HS Infiltration 1/3/2023 2:18:25 PM Page 7 Mitigated Routing WEST TRENCH Bottom Length:378.00 ft. Bottom Width:2.50 ft. Trench bottom slope 1:0 To 1 Trench Left side slope 0:0 To 1 Trench right side slope 2:0 To 1 Material thickness of first layer:4.17 Pour Space of material for first layer:0.4 Material thickness of second layer:0 Pour Space of material for second layer:0 Material thickness of third layer:0 Pour Space of material for third layer:0 Infiltration On Infiltration rate:20 Infiltration safety factor:1 Total Volume Infiltrated (ac-ft.):185.647 Total Volume Through Riser (ac-ft.):0 Total Volume Through Facility (ac-ft.):185.647 Percent Infiltrated:100 Total Precip Applied to Facility:0 Total Evap From Facility:0 Discharge Structure Riser Height:4.17 ft. Riser Diameter:0 in. Element Flows To: Outlet 1 Outlet 2 Gravel Trench Bed Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.021 0.000 0.000 0.000 0.0574 0.021 0.000 0.000 0.437 0.1149 0.021 0.001 0.000 0.437 0.1723 0.021 0.001 0.000 0.437 0.2298 0.021 0.002 0.000 0.437 0.2872 0.021 0.002 0.000 0.437 0.3447 0.021 0.003 0.000 0.437 0.4021 0.021 0.003 0.000 0.437 0.4596 0.021 0.004 0.000 0.437 0.5170 0.021 0.004 0.000 0.437 0.5744 0.021 0.005 0.000 0.437 0.6319 0.021 0.005 0.000 0.437 0.6893 0.021 0.006 0.000 0.437 0.7468 0.021 0.006 0.000 0.437 0.8042 0.021 0.007 0.000 0.437 0.8617 0.021 0.007 0.000 0.437 0.9191 0.021 0.008 0.000 0.437 0.9766 0.021 0.008 0.000 0.437 1.0340 0.021 0.009 0.000 0.437 1.0914 0.021 0.009 0.000 0.437 1.1489 0.021 0.010 0.000 0.437 1.2063 0.021 0.010 0.000 0.437 1.2638 0.021 0.011 0.000 0.437 1.3212 0.021 0.011 0.000 0.437 Yelm HS Infiltration 1/3/2023 2:18:25 PM Page 8 1.3787 0.021 0.012 0.000 0.437 1.4361 0.021 0.012 0.000 0.437 1.4936 0.021 0.013 0.000 0.437 1.5510 0.021 0.013 0.000 0.437 1.6084 0.021 0.014 0.000 0.437 1.6659 0.021 0.014 0.000 0.437 1.7233 0.021 0.015 0.000 0.437 1.7808 0.021 0.015 0.000 0.437 1.8382 0.021 0.016 0.000 0.437 1.8957 0.021 0.016 0.000 0.437 1.9531 0.021 0.016 0.000 0.437 2.0106 0.021 0.017 0.000 0.437 2.0680 0.021 0.017 0.000 0.437 2.1254 0.021 0.018 0.000 0.437 2.1829 0.021 0.018 0.000 0.437 2.2403 0.021 0.019 0.000 0.437 2.2978 0.021 0.019 0.000 0.437 2.3552 0.021 0.020 0.000 0.437 2.4127 0.021 0.020 0.000 0.437 2.4701 0.021 0.021 0.000 0.437 2.5276 0.021 0.021 0.000 0.437 2.5850 0.021 0.022 0.000 0.437 2.6424 0.021 0.022 0.000 0.437 2.6999 0.021 0.023 0.000 0.437 2.7573 0.021 0.023 0.000 0.437 2.8148 0.021 0.024 0.000 0.437 2.8722 0.021 0.024 0.000 0.437 2.9297 0.021 0.025 0.000 0.437 2.9871 0.021 0.025 0.000 0.437 3.0446 0.021 0.026 0.000 0.437 3.1020 0.021 0.026 0.000 0.437 3.1594 0.021 0.027 0.000 0.437 3.2169 0.021 0.027 0.000 0.437 3.2743 0.021 0.028 0.000 0.437 3.3318 0.021 0.028 0.000 0.437 3.3892 0.021 0.029 0.000 0.437 3.4467 0.021 0.029 0.000 0.437 3.5041 0.021 0.030 0.000 0.437 3.5616 0.021 0.030 0.000 0.437 3.6190 0.021 0.031 0.000 0.437 3.6764 0.021 0.031 0.000 0.437 3.7339 0.021 0.032 0.000 0.437 3.7913 0.021 0.032 0.000 0.437 3.8488 0.021 0.033 0.000 0.437 3.9062 0.021 0.033 0.000 0.437 3.9637 0.021 0.034 0.000 0.437 4.0211 0.021 0.034 0.000 0.437 4.0786 0.021 0.035 0.000 0.437 4.1360 0.021 0.035 0.000 0.437 4.1934 0.021 0.037 0.000 0.437 4.2509 0.021 0.038 0.000 0.437 4.3083 0.021 0.039 0.000 0.437 4.3658 0.021 0.040 0.000 0.437 4.4232 0.021 0.042 0.000 0.437 4.4807 0.021 0.043 0.000 0.437 4.5381 0.021 0.044 0.000 0.437 4.5956 0.021 0.045 0.000 0.437 4.6530 0.021 0.047 0.000 0.437 Yelm HS Infiltration 1/3/2023 2:18:25 PM Page 9 4.7104 0.021 0.048 0.000 0.437 4.7679 0.021 0.049 0.000 0.437 4.8253 0.021 0.050 0.000 0.437 4.8828 0.021 0.052 0.000 0.437 4.9402 0.021 0.053 0.000 0.437 4.9977 0.021 0.054 0.000 0.437 5.0551 0.021 0.055 0.000 0.437 5.1126 0.021 0.057 0.000 0.437 Yelm HS Infiltration 1/3/2023 2:18:25 PM Page 10 EAST TRENCH Bottom Length:400.00 ft. Bottom Width:225.00 ft. Trench bottom slope 1:0 To 1 Trench Left side slope 0:0 To 1 Trench right side slope 2:0 To 1 Material thickness of first layer:0.5 Pour Space of material for first layer:0.4 Material thickness of second layer:0 Pour Space of material for second layer:0 Material thickness of third layer:0 Pour Space of material for third layer:0 Infiltration On Infiltration rate:4.85 Infiltration safety factor:1 Total Volume Infiltrated (ac-ft.):33.564 Total Volume Through Riser (ac-ft.):0 Total Volume Through Facility (ac-ft.):33.564 Percent Infiltrated:100 Total Precip Applied to Facility:0 Total Evap From Facility:0 Discharge Structure Riser Height:0.5 ft. Riser Diameter:0 in. Element Flows To: Outlet 1 Outlet 2 Gravel Trench Bed Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 2.066 0.000 0.000 0.000 0.0167 2.066 0.013 0.000 10.10 0.0333 2.066 0.027 0.000 10.10 0.0500 2.066 0.041 0.000 10.10 0.0667 2.066 0.055 0.000 10.10 0.0833 2.066 0.068 0.000 10.10 0.1000 2.066 0.082 0.000 10.10 0.1167 2.066 0.096 0.000 10.10 0.1333 2.066 0.110 0.000 10.10 0.1500 2.066 0.124 0.000 10.10 0.1667 2.066 0.137 0.000 10.10 0.1833 2.066 0.151 0.000 10.10 0.2000 2.066 0.165 0.000 10.10 0.2167 2.066 0.179 0.000 10.10 0.2333 2.066 0.192 0.000 10.10 0.2500 2.066 0.206 0.000 10.10 0.2667 2.066 0.220 0.000 10.10 0.2833 2.066 0.234 0.000 10.10 0.3000 2.066 0.247 0.000 10.10 0.3167 2.066 0.261 0.000 10.10 0.3333 2.066 0.275 0.000 10.10 0.3500 2.066 0.289 0.000 10.10 0.3667 2.066 0.303 0.000 10.10 0.3833 2.066 0.316 0.000 10.10 0.4000 2.066 0.330 0.000 10.10 0.4167 2.066 0.344 0.000 10.10 Yelm HS Infiltration 1/3/2023 2:18:25 PM Page 11 0.4333 2.066 0.358 0.000 10.10 0.4500 2.066 0.371 0.000 10.10 0.4667 2.066 0.385 0.000 10.10 0.4833 2.066 0.399 0.000 10.10 0.5000 2.066 0.413 0.000 10.10 0.5167 2.066 0.447 0.000 10.10 0.5333 2.066 0.482 0.000 10.10 0.5500 2.066 0.516 0.000 10.10 0.5667 2.066 0.551 0.000 10.10 0.5833 2.066 0.585 0.000 10.10 0.6000 2.066 0.619 0.000 10.10 0.6167 2.066 0.654 0.000 10.10 0.6333 2.066 0.688 0.000 10.10 0.6500 2.066 0.723 0.000 10.10 0.6667 2.066 0.757 0.000 10.10 0.6833 2.066 0.792 0.000 10.10 0.7000 2.066 0.826 0.000 10.10 0.7167 2.066 0.860 0.000 10.10 0.7333 2.066 0.895 0.000 10.10 0.7500 2.066 0.929 0.000 10.10 0.7667 2.066 0.964 0.000 10.10 0.7833 2.066 0.998 0.000 10.10 0.8000 2.066 1.033 0.000 10.10 0.8167 2.066 1.067 0.000 10.10 0.8333 2.066 1.101 0.000 10.10 0.8500 2.066 1.136 0.000 10.10 0.8667 2.066 1.170 0.000 10.10 0.8833 2.066 1.205 0.000 10.10 0.9000 2.066 1.239 0.000 10.10 0.9167 2.066 1.274 0.000 10.10 0.9333 2.066 1.308 0.000 10.10 0.9500 2.066 1.343 0.000 10.10 0.9667 2.066 1.377 0.000 10.10 0.9833 2.066 1.411 0.000 10.10 1.0000 2.066 1.446 0.000 10.10 1.0167 2.066 1.480 0.000 10.10 1.0333 2.066 1.515 0.000 10.10 1.0500 2.066 1.549 0.000 10.10 1.0667 2.066 1.584 0.000 10.10 1.0833 2.066 1.618 0.000 10.10 1.1000 2.066 1.652 0.000 10.10 1.1167 2.066 1.687 0.000 10.10 1.1333 2.066 1.721 0.000 10.10 1.1500 2.066 1.756 0.000 10.10 1.1667 2.066 1.790 0.000 10.10 1.1833 2.066 1.825 0.000 10.10 1.2000 2.066 1.859 0.000 10.10 1.2167 2.066 1.893 0.000 10.10 1.2333 2.066 1.928 0.000 10.10 1.2500 2.066 1.962 0.000 10.10 1.2667 2.066 1.997 0.000 10.10 1.2833 2.066 2.031 0.000 10.10 1.3000 2.066 2.066 0.000 10.10 1.3167 2.066 2.100 0.000 10.10 1.3333 2.066 2.135 0.000 10.10 1.3500 2.066 2.169 0.000 10.10 1.3667 2.066 2.203 0.000 10.10 1.3833 2.066 2.238 0.000 10.10 Yelm HS Infiltration 1/3/2023 2:18:25 PM Page 12 1.4000 2.066 2.272 0.000 10.10 1.4167 2.066 2.307 0.000 10.10 1.4333 2.066 2.341 0.000 10.10 1.4500 2.066 2.376 0.000 10.10 1.4667 2.066 2.410 0.000 10.10 1.4833 2.066 2.444 0.000 10.10 1.5000 2.066 2.479 0.000 10.10 Yelm HS Infiltration 1/3/2023 2:18:25 PM Page 13 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:3.47 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:2.07 Total Impervious Area:1.4 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.002688 5 year 0.004602 10 year 0.006353 25 year 0.009255 50 year 0.012019 100 year 0.015394 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1956 0.019 0.000 1957 0.003 0.000 1958 0.003 0.000 1959 0.003 0.000 1960 0.003 0.000 1961 0.003 0.000 1962 0.003 0.000 1963 0.003 0.000 1964 0.003 0.000 1965 0.003 0.000 Yelm HS Infiltration 1/3/2023 2:36:15 PM Page 14 1966 0.003 0.000 1967 0.003 0.000 1968 0.003 0.000 1969 0.003 0.000 1970 0.003 0.000 1971 0.008 0.000 1972 0.058 0.000 1973 0.003 0.000 1974 0.003 0.000 1975 0.003 0.000 1976 0.003 0.000 1977 0.003 0.000 1978 0.003 0.000 1979 0.003 0.000 1980 0.003 0.000 1981 0.003 0.000 1982 0.003 0.000 1983 0.003 0.000 1984 0.003 0.000 1985 0.003 0.000 1986 0.003 0.000 1987 0.003 0.000 1988 0.002 0.000 1989 0.003 0.000 1990 0.003 0.000 1991 0.010 0.000 1992 0.003 0.000 1993 0.003 0.000 1994 0.002 0.000 1995 0.003 0.000 1996 0.003 0.000 1997 0.003 0.000 1998 0.003 0.000 1999 0.003 0.000 2000 0.002 0.000 2001 0.002 0.000 2002 0.001 0.000 2003 0.002 0.000 2004 0.003 0.000 2005 0.001 0.000 2006 0.002 0.000 2007 0.003 0.000 2008 0.001 0.000 2009 0.003 0.000 2010 0.003 0.000 2011 0.003 0.000 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0578 0.0000 2 0.0194 0.0000 3 0.0100 0.0000 4 0.0078 0.0000 5 0.0028 0.0000 6 0.0028 0.0000 7 0.0028 0.0000 8 0.0028 0.0000 Yelm HS Infiltration 1/3/2023 2:36:15 PM Page 15 9 0.0028 0.0000 10 0.0028 0.0000 11 0.0028 0.0000 12 0.0028 0.0000 13 0.0028 0.0000 14 0.0028 0.0000 15 0.0028 0.0000 16 0.0028 0.0000 17 0.0028 0.0000 18 0.0028 0.0000 19 0.0028 0.0000 20 0.0028 0.0000 21 0.0028 0.0000 22 0.0028 0.0000 23 0.0028 0.0000 24 0.0028 0.0000 25 0.0028 0.0000 26 0.0028 0.0000 27 0.0028 0.0000 28 0.0027 0.0000 29 0.0027 0.0000 30 0.0027 0.0000 31 0.0027 0.0000 32 0.0027 0.0000 33 0.0027 0.0000 34 0.0027 0.0000 35 0.0027 0.0000 36 0.0027 0.0000 37 0.0027 0.0000 38 0.0027 0.0000 39 0.0027 0.0000 40 0.0027 0.0000 41 0.0027 0.0000 42 0.0027 0.0000 43 0.0026 0.0000 44 0.0026 0.0000 45 0.0026 0.0000 46 0.0026 0.0000 47 0.0025 0.0000 48 0.0025 0.0000 49 0.0022 0.0000 50 0.0022 0.0000 51 0.0022 0.0000 52 0.0020 0.0000 53 0.0017 0.0000 54 0.0013 0.0000 55 0.0010 0.0000 56 0.0008 0.0000 Yelm HS Infiltration 1/3/2023 2:36:15 PM Page 16 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0013 4194 0 0 Pass 0.0015 3613 0 0 Pass 0.0016 3104 0 0 Pass 0.0017 2639 0 0 Pass 0.0018 2231 0 0 Pass 0.0019 1879 0 0 Pass 0.0020 1608 0 0 Pass 0.0021 1354 0 0 Pass 0.0022 1159 0 0 Pass 0.0023 921 0 0 Pass 0.0024 663 0 0 Pass 0.0025 456 0 0 Pass 0.0026 268 0 0 Pass 0.0027 115 0 0 Pass 0.0029 22 0 0 Pass 0.0030 21 0 0 Pass 0.0031 21 0 0 Pass 0.0032 20 0 0 Pass 0.0033 19 0 0 Pass 0.0034 19 0 0 Pass 0.0035 18 0 0 Pass 0.0036 18 0 0 Pass 0.0037 18 0 0 Pass 0.0038 17 0 0 Pass 0.0039 16 0 0 Pass 0.0040 16 0 0 Pass 0.0041 16 0 0 Pass 0.0043 14 0 0 Pass 0.0044 13 0 0 Pass 0.0045 12 0 0 Pass 0.0046 12 0 0 Pass 0.0047 12 0 0 Pass 0.0048 11 0 0 Pass 0.0049 11 0 0 Pass 0.0050 11 0 0 Pass 0.0051 11 0 0 Pass 0.0052 10 0 0 Pass 0.0053 10 0 0 Pass 0.0054 10 0 0 Pass 0.0055 10 0 0 Pass 0.0057 10 0 0 Pass 0.0058 10 0 0 Pass 0.0059 9 0 0 Pass 0.0060 9 0 0 Pass 0.0061 9 0 0 Pass 0.0062 9 0 0 Pass 0.0063 9 0 0 Pass 0.0064 9 0 0 Pass 0.0065 9 0 0 Pass 0.0066 9 0 0 Pass 0.0067 9 0 0 Pass 0.0068 9 0 0 Pass 0.0070 8 0 0 Pass Yelm HS Infiltration 1/3/2023 2:36:15 PM Page 17 0.0071 8 0 0 Pass 0.0072 8 0 0 Pass 0.0073 8 0 0 Pass 0.0074 8 0 0 Pass 0.0075 7 0 0 Pass 0.0076 7 0 0 Pass 0.0077 7 0 0 Pass 0.0078 6 0 0 Pass 0.0079 6 0 0 Pass 0.0080 6 0 0 Pass 0.0081 6 0 0 Pass 0.0082 6 0 0 Pass 0.0084 6 0 0 Pass 0.0085 6 0 0 Pass 0.0086 6 0 0 Pass 0.0087 6 0 0 Pass 0.0088 6 0 0 Pass 0.0089 6 0 0 Pass 0.0090 6 0 0 Pass 0.0091 6 0 0 Pass 0.0092 6 0 0 Pass 0.0093 6 0 0 Pass 0.0094 6 0 0 Pass 0.0095 6 0 0 Pass 0.0096 6 0 0 Pass 0.0098 5 0 0 Pass 0.0099 5 0 0 Pass 0.0100 4 0 0 Pass 0.0101 4 0 0 Pass 0.0102 4 0 0 Pass 0.0103 4 0 0 Pass 0.0104 4 0 0 Pass 0.0105 4 0 0 Pass 0.0106 4 0 0 Pass 0.0107 4 0 0 Pass 0.0108 4 0 0 Pass 0.0109 4 0 0 Pass 0.0110 4 0 0 Pass 0.0112 4 0 0 Pass 0.0113 4 0 0 Pass 0.0114 4 0 0 Pass 0.0115 4 0 0 Pass 0.0116 4 0 0 Pass 0.0117 4 0 0 Pass 0.0118 4 0 0 Pass 0.0119 4 0 0 Pass 0.0120 4 0 0 Pass Yelm HS Infiltration 1/3/2023 2:36:15 PM Page 18 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. Yelm HS Infiltration 1/3/2023 2:36:15 PM Page 19 LID Report Yelm HS Infiltration 1/3/2023 2:36:42 PM Page 20 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. Yelm HS Infiltration 1/3/2023 2:36:42 PM Page 21 Appendix Predeveloped Schematic Yelm HS Infiltration 1/3/2023 2:36:45 PM Page 22 Mitigated Schematic Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 23 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 Yelm HS Infiltration.wdm MESSU 25 PreYelm HS Infiltration.MES 27 PreYelm HS Infiltration.L61 28 PreYelm HS Infiltration.L62 30 POCYelm HS Infiltration1.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 Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 24 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 Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 25 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 1 3.47 COPY 501 12 PERLND 1 3.47 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 Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 26 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 Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 27 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 Yelm HS Infiltration.wdm MESSU 25 MitYelm HS Infiltration.MES 27 MitYelm HS Infiltration.L61 28 MitYelm HS Infiltration.L62 30 POCYelm HS Infiltration1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 IMPLND 8 PERLND 7 RCHRES 1 RCHRES 2 COPY 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 WEST TRENCH 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 *** 7 A/B, Lawn, Flat 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 7 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 28 # - # 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 *** 8 SIDEWALKS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 8 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 8 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 8 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 8 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 29 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 8 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 8 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** WEST BASIN*** IMPLND 8 1.19 RCHRES 1 5 EAST BASIN*** PERLND 7 2.07 RCHRES 2 2 PERLND 7 2.07 RCHRES 2 3 IMPLND 8 0.21 RCHRES 2 5 ******Routing****** IMPLND 8 1.19 COPY 1 15 PERLND 7 2.07 COPY 1 12 IMPLND 8 0.21 COPY 1 15 PERLND 7 2.07 COPY 1 13 RCHRES 1 1 COPY 501 17 RCHRES 2 1 COPY 501 17 END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-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 WEST TRENCH 2 1 1 1 28 0 1 2 EAST TRENCH 2 1 1 1 28 0 1 END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 2 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 2 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 30 FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** 1 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 2 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** 1 1 0.07 0.0 0.0 0.5 0.0 2 2 0.08 0.0 0.0 0.5 0.0 END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> 1 0 4.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2 0 4.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES FTABLE 1 91 5 Depth Area Volume Outflow1 Outflow2 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.021694 0.000000 0.000000 0.000000 0.057444 0.021694 0.000498 0.000000 0.437500 0.114889 0.021694 0.000997 0.000000 0.437500 0.172333 0.021694 0.001495 0.000000 0.437500 0.229778 0.021694 0.001994 0.000000 0.437500 0.287222 0.021694 0.002492 0.000000 0.437500 0.344667 0.021694 0.002991 0.000000 0.437500 0.402111 0.021694 0.003489 0.000000 0.437500 0.459556 0.021694 0.003988 0.000000 0.437500 0.517000 0.021694 0.004486 0.000000 0.437500 0.574444 0.021694 0.004985 0.000000 0.437500 0.631889 0.021694 0.005483 0.000000 0.437500 0.689333 0.021694 0.005982 0.000000 0.437500 0.746778 0.021694 0.006480 0.000000 0.437500 0.804222 0.021694 0.006979 0.000000 0.437500 0.861667 0.021694 0.007477 0.000000 0.437500 0.919111 0.021694 0.007976 0.000000 0.437500 0.976556 0.021694 0.008474 0.000000 0.437500 1.034000 0.021694 0.008973 0.000000 0.437500 1.091444 0.021694 0.009471 0.000000 0.437500 1.148889 0.021694 0.009970 0.000000 0.437500 1.206333 0.021694 0.010468 0.000000 0.437500 1.263778 0.021694 0.010967 0.000000 0.437500 1.321222 0.021694 0.011465 0.000000 0.437500 1.378667 0.021694 0.011964 0.000000 0.437500 1.436111 0.021694 0.012462 0.000000 0.437500 1.493556 0.021694 0.012961 0.000000 0.437500 1.551000 0.021694 0.013459 0.000000 0.437500 1.608444 0.021694 0.013958 0.000000 0.437500 1.665889 0.021694 0.014456 0.000000 0.437500 1.723333 0.021694 0.014955 0.000000 0.437500 1.780778 0.021694 0.015453 0.000000 0.437500 1.838222 0.021694 0.015952 0.000000 0.437500 1.895667 0.021694 0.016450 0.000000 0.437500 1.953111 0.021694 0.016948 0.000000 0.437500 2.010556 0.021694 0.017447 0.000000 0.437500 2.068000 0.021694 0.017945 0.000000 0.437500 2.125444 0.021694 0.018444 0.000000 0.437500 2.182889 0.021694 0.018942 0.000000 0.437500 2.240333 0.021694 0.019441 0.000000 0.437500 2.297778 0.021694 0.019939 0.000000 0.437500 Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 31 2.355222 0.021694 0.020438 0.000000 0.437500 2.412667 0.021694 0.020936 0.000000 0.437500 2.470111 0.021694 0.021435 0.000000 0.437500 2.527556 0.021694 0.021933 0.000000 0.437500 2.585000 0.021694 0.022432 0.000000 0.437500 2.642444 0.021694 0.022930 0.000000 0.437500 2.699889 0.021694 0.023429 0.000000 0.437500 2.757333 0.021694 0.023927 0.000000 0.437500 2.814778 0.021694 0.024426 0.000000 0.437500 2.872222 0.021694 0.024924 0.000000 0.437500 2.929667 0.021694 0.025423 0.000000 0.437500 2.987111 0.021694 0.025921 0.000000 0.437500 3.044556 0.021694 0.026420 0.000000 0.437500 3.102000 0.021694 0.026918 0.000000 0.437500 3.159444 0.021694 0.027417 0.000000 0.437500 3.216889 0.021694 0.027915 0.000000 0.437500 3.274333 0.021694 0.028414 0.000000 0.437500 3.331778 0.021694 0.028912 0.000000 0.437500 3.389222 0.021694 0.029411 0.000000 0.437500 3.446667 0.021694 0.029909 0.000000 0.437500 3.504111 0.021694 0.030408 0.000000 0.437500 3.561556 0.021694 0.030906 0.000000 0.437500 3.619000 0.021694 0.031405 0.000000 0.437500 3.676444 0.021694 0.031903 0.000000 0.437500 3.733889 0.021694 0.032402 0.000000 0.437500 3.791333 0.021694 0.032900 0.000000 0.437500 3.848778 0.021694 0.033398 0.000000 0.437500 3.906222 0.021694 0.033897 0.000000 0.437500 3.963667 0.021694 0.034395 0.000000 0.437500 4.021111 0.021694 0.034894 0.000000 0.437500 4.078556 0.021694 0.035392 0.000000 0.437500 4.136000 0.021694 0.035891 0.000000 0.437500 4.193444 0.021694 0.037137 0.000000 0.437500 4.250889 0.021694 0.038383 0.000000 0.437500 4.308333 0.021694 0.039630 0.000000 0.437500 4.365778 0.021694 0.040876 0.000000 0.437500 4.423222 0.021694 0.042122 0.000000 0.437500 4.480667 0.021694 0.043368 0.000000 0.437500 4.538111 0.021694 0.044614 0.000000 0.437500 4.595556 0.021694 0.045861 0.000000 0.437500 4.653000 0.021694 0.047107 0.000000 0.437500 4.710444 0.021694 0.048353 0.000000 0.437500 4.767889 0.021694 0.049599 0.000000 0.437500 4.825333 0.021694 0.050845 0.000000 0.437500 4.882778 0.021694 0.052092 0.000000 0.437500 4.940222 0.021694 0.053338 0.000000 0.437500 4.997667 0.021694 0.054584 0.000000 0.437500 5.055111 0.021694 0.055830 0.000000 0.437500 5.112556 0.021694 0.057077 0.000000 0.437500 5.170000 0.021694 0.058323 0.000000 0.437500 END FTABLE 1 FTABLE 2 92 5 Depth Area Volume Outflow1 Outflow2 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 2.066116 0.000000 0.000000 0.000000 0.016667 2.066116 0.013774 0.000000 10.10417 0.033333 2.066116 0.027548 0.000000 10.10417 0.050000 2.066116 0.041322 0.000000 10.10417 0.066667 2.066116 0.055096 0.000000 10.10417 0.083333 2.066116 0.068871 0.000000 10.10417 0.100000 2.066116 0.082645 0.000000 10.10417 0.116667 2.066116 0.096419 0.000000 10.10417 0.133333 2.066116 0.110193 0.000000 10.10417 0.150000 2.066116 0.123967 0.000000 10.10417 0.166667 2.066116 0.137741 0.000000 10.10417 0.183333 2.066116 0.151515 0.000000 10.10417 0.200000 2.066116 0.165289 0.000000 10.10417 0.216667 2.066116 0.179063 0.000000 10.10417 0.233333 2.066116 0.192837 0.000000 10.10417 Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 32 0.250000 2.066116 0.206612 0.000000 10.10417 0.266667 2.066116 0.220386 0.000000 10.10417 0.283333 2.066116 0.234160 0.000000 10.10417 0.300000 2.066116 0.247934 0.000000 10.10417 0.316667 2.066116 0.261708 0.000000 10.10417 0.333333 2.066116 0.275482 0.000000 10.10417 0.350000 2.066116 0.289256 0.000000 10.10417 0.366667 2.066116 0.303030 0.000000 10.10417 0.383333 2.066116 0.316804 0.000000 10.10417 0.400000 2.066116 0.330579 0.000000 10.10417 0.416667 2.066116 0.344353 0.000000 10.10417 0.433333 2.066116 0.358127 0.000000 10.10417 0.450000 2.066116 0.371901 0.000000 10.10417 0.466667 2.066116 0.385675 0.000000 10.10417 0.483333 2.066116 0.399449 0.000000 10.10417 0.500000 2.066116 0.413223 0.000000 10.10417 0.516667 2.066116 0.447658 0.000000 10.10417 0.533333 2.066116 0.482094 0.000000 10.10417 0.550000 2.066116 0.516529 0.000000 10.10417 0.566667 2.066116 0.550964 0.000000 10.10417 0.583333 2.066116 0.585399 0.000000 10.10417 0.600000 2.066116 0.619835 0.000000 10.10417 0.616667 2.066116 0.654270 0.000000 10.10417 0.633333 2.066116 0.688705 0.000000 10.10417 0.650000 2.066116 0.723140 0.000000 10.10417 0.666667 2.066116 0.757576 0.000000 10.10417 0.683333 2.066116 0.792011 0.000000 10.10417 0.700000 2.066116 0.826446 0.000000 10.10417 0.716667 2.066116 0.860882 0.000000 10.10417 0.733333 2.066116 0.895317 0.000000 10.10417 0.750000 2.066116 0.929752 0.000000 10.10417 0.766667 2.066116 0.964187 0.000000 10.10417 0.783333 2.066116 0.998623 0.000000 10.10417 0.800000 2.066116 1.033058 0.000000 10.10417 0.816667 2.066116 1.067493 0.000000 10.10417 0.833333 2.066116 1.101928 0.000000 10.10417 0.850000 2.066116 1.136364 0.000000 10.10417 0.866667 2.066116 1.170799 0.000000 10.10417 0.883333 2.066116 1.205234 0.000000 10.10417 0.900000 2.066116 1.239669 0.000000 10.10417 0.916667 2.066116 1.274105 0.000000 10.10417 0.933333 2.066116 1.308540 0.000000 10.10417 0.950000 2.066116 1.342975 0.000000 10.10417 0.966667 2.066116 1.377410 0.000000 10.10417 0.983333 2.066116 1.411846 0.000000 10.10417 1.000000 2.066116 1.446281 0.000000 10.10417 1.016667 2.066116 1.480716 0.000000 10.10417 1.033333 2.066116 1.515152 0.000000 10.10417 1.050000 2.066116 1.549587 0.000000 10.10417 1.066667 2.066116 1.584022 0.000000 10.10417 1.083333 2.066116 1.618457 0.000000 10.10417 1.100000 2.066116 1.652893 0.000000 10.10417 1.116667 2.066116 1.687328 0.000000 10.10417 1.133333 2.066116 1.721763 0.000000 10.10417 1.150000 2.066116 1.756198 0.000000 10.10417 1.166667 2.066116 1.790634 0.000000 10.10417 1.183333 2.066116 1.825069 0.000000 10.10417 1.200000 2.066116 1.859504 0.000000 10.10417 1.216667 2.066116 1.893939 0.000000 10.10417 1.233333 2.066116 1.928375 0.000000 10.10417 1.250000 2.066116 1.962810 0.000000 10.10417 1.266667 2.066116 1.997245 0.000000 10.10417 1.283333 2.066116 2.031680 0.000000 10.10417 1.300000 2.066116 2.066116 0.000000 10.10417 1.316667 2.066116 2.100551 0.000000 10.10417 1.333333 2.066116 2.134986 0.000000 10.10417 1.350000 2.066116 2.169421 0.000000 10.10417 1.366667 2.066116 2.203857 0.000000 10.10417 1.383333 2.066116 2.238292 0.000000 10.10417 1.400000 2.066116 2.272727 0.000000 10.10417 Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 33 1.416667 2.066116 2.307163 0.000000 10.10417 1.433333 2.066116 2.341598 0.000000 10.10417 1.450000 2.066116 2.376033 0.000000 10.10417 1.466667 2.066116 2.410468 0.000000 10.10417 1.483333 2.066116 2.444904 0.000000 10.10417 1.500000 2.066116 2.479339 0.000000 10.10417 1.516667 2.066116 2.513774 0.000000 10.10417 END FTABLE 2 END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 0.857 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 0.857 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** RCHRES 1 HYDR RO 1 1 1 WDM 1000 FLOW ENGL REPL RCHRES 1 HYDR O 1 1 1 WDM 1001 FLOW ENGL REPL RCHRES 1 HYDR O 2 1 1 WDM 1002 FLOW ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1003 STAG ENGL REPL COPY 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 RCHRES 2 HYDR RO 1 1 1 WDM 1004 FLOW ENGL REPL RCHRES 2 HYDR O 1 1 1 WDM 1005 FLOW ENGL REPL RCHRES 2 HYDR O 2 1 1 WDM 1006 FLOW ENGL REPL RCHRES 2 HYDR STAGE 1 1 1 WDM 1007 STAG ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 2 PERLND PWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 2 MASS-LINK 3 PERLND PWATER IFWO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 3 MASS-LINK 5 IMPLND IWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 5 MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 MASS-LINK 17 RCHRES OFLOW OVOL 1 COPY INPUT MEAN END MASS-LINK 17 END MASS-LINK END RUN Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 34 Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 35 Predeveloped HSPF Message File Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 36 Mitigated HSPF Message File Yelm HS Infiltration 1/3/2023 2:36:49 PM Page 37 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. 2005-2023; 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 APPENDIX C CSWPPP PRELIMINARY Stormwater Pollution Prevention Plan (SWPPP) YELM HIGH SCHOOL SOCCER FIELD CONVERSION AND TENNIS COURT RECONSTRUCTION KPFF Project # 10182200114 December 30, 2022 Prepared by: Ben Enfield, PE Consulting Engineers 612 Woodland Square Loop SE, Suite 100 Lacey, WA 98503 (360) 292-7230 (360) 292-7231 FAX Construction Stormwater General Permit (CSWGP) Stormwater Pollution Prevention Plan (SWPPP) for Yelm High School Soccer Field Conversion and Tennis Court Reconstruction Prepared for: Department of Ecology Northwest Regional Office Permittee / Owner Developer Operator / Contractor Yelm High School Yelm High School TBD Certified Erosion and Sediment Control Lead (CESCL) Name Organization Contact Phone Number TBD - - SWPPP Prepared By Name Organization Contact Phone Number Ben Enfield KPFF Consulting Engineers (360) 292-7230 SWPPP Preparation Date 9/1/2020 Project Construction Dates Activity / Phase Start Date End Date Site Improvements TBD TBD TABLE OF CONTENTS Project Information __________________________________________________ 1 Existing Conditions __________________________________________________ 1 Proposed Construction Activities _______________________________________ 2 Construction Stormwater Best Management Practices (BMPs) ______________ 3 The 13 Elements ____________________________________________________ 3 Element 1: Preserve Vegetation/Mark Clearing Limits _____________________ 3 Element 2: Establish Construction Access ______________________________ 4 Element 3: Control Flow Rates ______________________________________ 5 Element 4: Install Sediment Controls __________________________________ 6 Element 5: Stabilize Soils ___________________________________________ 7 Element 6: Protect Slopes __________________________________________ 8 Element 7: Protect Drain Inlets ______________________________________ 9 Element 8: Stabilize Channels and Outlets ____________________________ 10 Element 9: Control Pollutants _______________________________________ 11 Element 10: Control Dewatering ____________________________________ 14 Element 11: Maintain BMPs ________________________________________ 15 Element 12: Manage the Project ____________________________________ 16 Element 13: Protect Low Impact Development _________________________ 19 Pollution Prevention Team ___________________________________________ 20 Monitoring and Sampling Requirements ________________________________ 21 Site Inspection ____________________________________________________ 21 Stormwater Quality Sampling _________________________________________ 21 Turbidity Sampling _______________________________________________ 21 pH Sampling ____________________________________________________ 23 Discharges to 303 (d) or Total Maximum Daily Load (TMDL) Waterbodies_____ 24 303 (d) Listed Waterbodies __________________________________________ 24 TMDL Waterbodies ________________________________________________ 24 Reporting and Record Keeping ________________________________________ 25 Record Keeping ___________________________________________________ 25 Site Log Book ___________________________________________________ 25 Records Retention _______________________________________________ 25 Updating the SWPPP _____________________________________________ 25 Reporting ________________________________________________________ 26 Discharge Monitoring Reports ______________________________________ 26 Notification of Noncompliance ______________________________________ 26 List of Tables Table 1 _____________________________________________________________ 1 Table 2 ____________________________________________________________ 11 Table 3 ____________________________________________________________ 12 Table 4 ____________________________________________________________ 14 Table 5 ____________________________________________________________ 16 Table 6 ____________________________________________________________ 17 Table 7 ____________________________________________________________ 20 Table 8 ____________________________________________________________ 21 Table 9 ____________________________________________________________ 23 List of Appendices A. Site Map B. BMP Details C. Correspondence D. Site Inspection Form E. Construction Stormwater General Permit (CSWGP) 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 1 Project Information (1.0) Project/Site Name: Yelm High School Street/Location: 1315 W Yelm Ave City: Yelm State: WA Zip code: 98597 Subdivision: n/a Receiving waterbody: Groundwater Existing Conditions (1.1) Total acreage: 36.6 acres Disturbed acreage: 3.5 acres Existing structures: Yelm High School Campus Land cover: The site is developed as a high school campus with multiple buildings, parking lots, athletic fields, and landscape areas. Landscape topography: The project site is generally flat but slopes from northeast to southwest with typical slopes of less than 2% Drainage patterns: There are onsite stormwater treatment and infiltration areas for existing parking lots. Generally, stormwater runoff from the site is handled as sheet flow and infiltrates onsite. Runoff currently infiltrates on-site and sheet flows off-site along the south and east property lines of the project site. Any runoff that does not infiltrate on-site sheet flows to the southwest toward Thompson Creek. Thompson Creek, at its closest point, is located approximately 450 feet southwest of the southwest property corner. The drainage pattern at the project site is also flat with slopes less than 2%. The existing tennis courts are constructed with a crown running north-south and the field is sloped at less than 1% slope to the north. Existing Vegetation: The campus is fully developed. Pervious areas are grass or landscape. Critical Areas (wetlands, streams, flood zone and high erosion risk): The project site is not within the floodway, high groundwater area, or wetland review areas associated with Thompson Creek. The site is located in a category 1 critical aquifer recharge area. 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 None - - - 2 Proposed Construction Activities (1.2) Description of site development: The proposed project will be replacement and improvement of existing tennis courts and sports field. Description of construction activities: TESC installation, site grading, trenching & installation for underground utilities (stormwater), and surface improvements. Description of site drainage including flow from and onto adjacent properties. Must be consistent with Site Map in Appendix A: All stormwater runoff will be collected within the project area and infiltrated. Description of final stabilization: Final stabilization will consist of landscaping and paving. Contaminated Site Information: Proposed activities regarding contaminated soils or groundwater (example: on-site treatment system, authorized sanitary sewer discharge): None known or suspected. 3 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 13 Elements (2.1) Element 1: Preserve Vegetation / Mark Clearing Limits (2.1.1) To protect adjacent areas and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. List and describe BMPs: BMP C101: Preserving Natural Vegetation BMP C233: Silt Fence Installation Schedules: Prior to land disturbing activities and as needed. Inspection and Maintenance plan: Per BMP Maintenance Standards. It is the CESCL’s responsibility to ensure that all necessary BMPs are adequately installed prior to land disturbing activities. Once installed, the CESCL must perform periodic inspections to ensure that all BMPs are functioning properly. The CESCL may also suggest the installation of additional BMPs not listed above. Responsible Staff: Contractor provided CESCL. 4 Element 2: Establish Construction Access (2.1.2) A stabilized construction entrances will be provided off 93rd Ave SE. A construction staging area is proposed in the gravel parking lot just north of the field and adjacent to the proposed construction access. 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 to prevent sediment from leaving the site. All wash wastewater shall be controlled on-site. List and describe BMPs: BMP C105: Stabilized Construction Access BMP C107: Construction Road/Parking Area Stabilization Construction road/parking area stabilization shall be implemented to keep the existing on-site roads clean. Installation Schedules: Prior to land disturbing activities. Inspection and Maintenance plan: Per BMP maintenance standards. It is the CESCL’s responsibility to ensure that all necessary BMPs are adequately installed prior to land disturbing activities. Once installed, the CESCL must inspect the construction entrance for silt and soil build up and also look for any soil washout on to hard surfaces. If soil washout is present, the CESCL must take appropriate actions to alleviate the problem. Responsible Staff: Contractor provided CESCL. 5 Element 3: Control Flow Rates (2.1.3) No flow control BMP’s are proposed as the site is currently developed and proposed activity will not increase the impervious area above what exists on site. Water Bars will be used a 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: BMP C203: Water Bars BMP C235: Wattles Installation Schedules: Prior to land disturbing activities and as needed. Inspection and Maintenance Plan: Per BMP maintenance standards sediment levels shall be monitored and sediment shall be removed to ensure proper performance of the check dams and sediment ponds. It is the CESCL’s responsibility to ensure that all necessary BMPs are adequately installed prior to land disturbing activities. Once installed, the CESCL must inspect the construction entrance for silt and soil build up and also look for any soil washout on to hard surfaces. If the above listed BMPs are inadequate at controlling flowrates, the CESCL must take appropriate actions to alleviate the problem Responsible Staff: Contractor provided CESCL 6 Element 4: Install Sediment Controls (2.1.4) All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP prior to being discharged offsite or to an infiltration facility. In addition, sediment will be removed from paved areas, in and adjacent to construction work areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on vehicle tires away from the site and to minimize wash off of sediments from adjacent streets in runoff. List and describe BMPs: BMP C220: Storm Drain Inlet Protection BMP C233: Silt Fence Installation Schedules: Prior to land disturbing activities and as needed. Inspection and Maintenance Plan: Per BMP maintenance standards. It is the CESCL’s responsibility to ensure that all necessary BMPs are adequately installed. Once installed, the CESCL must perform periodic inspections to ensure that all BMPs are functioning properly. The CESCL may also suggest the installation of additional BMPs not listed above. Responsible Staff: Contractor provided CESCL 7 Element 5: Stabilize Soils (2.1.5) Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. All stockpiled soils shall be stabilized from erosion, protected with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. 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: Summer 2023 End date: Fall 2023 Will you construct during the wet season? ☐Yes ☒No Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. List and describe BMPs: BMP C140: Dust Control BMP C120: Temporary and Permanent Seeding Installation Schedules: As needed. Inspection and Maintenance Plan: Per BMP maintenance standards. It is the CESCL’s responsibility to ensure that all necessary BMPs are adequately installed. Once installed, the CESCL must perform periodic inspections to ensure that all BMPs are functioning properly. The CESCL may also suggest the installation of additional BMPs not listed above. Responsible Staff: Contractor provided CESCL 8 Element 6: Protect Slopes (2.1.6) Not Applicable. No slopes are present or proposed. Will steep slopes be present at the site during construction? ☐Yes ☒No N/A Installation Schedules: N/A Inspection and Maintenance Plan: N/A Responsible Staff: N/A 9 Element 7: Protect Drain Inlets (2.1.7) All storm drain inlets existing and installed during construction shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. Storm Drain Inlet Protection (BMP C220) will be implemented for all drainage inlets and that could potentially be impacted by sediment-laden runoff on and near the project site. List and describe BMPs: BMP C220: Storm Drain Inlet Protection Installation Schedules: Prior to land disturbing activities. Inspection and Maintenance Plan: Per BMP maintenance standards. It is the CESCL’s responsibility to ensure that all necessary BMPs are adequately installed. Once installed, the CESCL must perform periodic inspections to ensure that all BMPs are functioning properly. Storm drain inlet protection should be regularly emptied and cleans to maximize effectiveness. Responsible Staff: Contractor provided CESCL 10 Element 8: Stabilize Channels and Outlets (2.1.8) N/A – No channels or direct discharge outlets are existing or proposed. List and describe BMPs: N/A Installation Schedules: N/A Inspection and Maintenance Plan: N/A Responsible Staff: N/A 11 Element 9: Control Pollutants (2.1.9) The following pollutants are anticipated to be present on-site: Table 2 – Pollutants Pollutant (and source, if applicable) Petroleum products for construction equipment Asphalt and concrete for site improvements etc. All pollutants, including waste materials and demolition debris, that occur on-site 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. List and describe BMPs: BMP C151: Concrete Handling BMP C153: Material Delivery, Storage and Containment BMPC154: Concrete Washout Area Volume IV – Source Control BMPs S407 BMPs for Dust Control at Disturbed Land Areas and Unpaved Roadways and Parking Lots S411 BMPs for Landscaping and Lawn/Vegetation Management S412 BMPs for Loading and Unloading Areas for Liquid and Solid Material S414 BMPs for Maintenance and Repair of Vehicles and Equipment S417 BMPs for Maintenance of Stormwater Drainage and Treatment Systems S419 BMPs for Mobile Fueling of Vehicles and Heavy Equipment S421 BMPs for Parking and Storage of Vehicles and Equipment S426 BMPs for Spills of Oil and Hazardous Materials Installation Schedules: As needed. Inspection and Maintenance Plan: Per BMP maintenance standards. It is the CESCL’s responsibility to ensure that all necessary BMPs are adequately installed. Once installed, the CESCL must perform periodic inspections to ensure that all BMPs are functioning properly. The CESCL may also suggest the installation of additional BMPs not listed above. Responsible Staff: Contractor provided CESCL. Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site? ☒Yes ☐No 12 List and describe BMPs: S412 BMPs for Loading and Unloading Areas for Liquid and Solid Material S414 BMPs for Maintenance and Repair of Vehicles and Equipment S419 BMPs for Mobile Fueling of Vehicles and Heavy Equipment S426 BMPs for Spills of Oil and Hazardous Materials Installation Schedules: As needed. Inspection and Maintenance Plan: As needed Responsible Staff: Per BMP maintenance standards. It is the CESCL’s responsibility to ensure that all necessary BMPs are adequately installed. Once installed, the CESCL must perform periodic inspections to ensure that all BMPs are functioning properly. The CESCL may also suggest the installation of additional BMPs not listed above. Will wheel wash or tire bath system BMPs be used during construction? ☐Yes ☒No Will pH-modifying sources be present on-site? ☒Yes ☐No Table 3 – pH-Modifying Sources None X Bulk cement Cement kiln dust Fly ash Other cementitious materials New concrete washing or curing waters Waste streams generated from concrete grinding and sawing Exposed aggregate processes Dewatering concrete vaults X Concrete pumping and mixer washout waters Recycled concrete Other (i.e. calcium lignosulfate) [please describe] List and describe BMPs: BMP C252: Treating and Disposing of High pH Water Installation Schedules: Inspection and Maintenance Plan: Per BMP maintenance standards. It is the CESCL’s responsibility to ensure that all necessary BMPs are adequately installed. Once installed, the CESCL must perform periodic inspections to ensure that all BMPs are functioning properly. The CESCL may also suggest the installation of additional BMPs not listed above. 13 Responsible Staff: Contractor provided CESCL 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. 14 Element 10: Control Dewatering (2.1.10) Dewatering is not anticipated to be necessary based on proposed work and site conditions. Groundwater was not encountered during geotechnical site explorations. Table 4 – Dewatering BMPs 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) List and describe BMPs: N/A Installation Schedules: N/A Inspection and Maintenance Plan: N/A Responsible Staff: Contractor provided CESCL 15 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. 16 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 X Design the project to fit the existing topography, soils, and drainage patterns X Emphasize erosion control rather than sediment control X Minimize the extent and duration of the area exposed X Keep runoff velocities low X Retain sediment on-site X Thoroughly monitor site and maintain all ESC measures X Schedule major earthwork during the dry season Other (please describe) 17 Table 6 – BMP Implementation Schedule Phase of Construction Project Stormwater BMPs Date Wet/Dry Season TBD TBD TBD TBD 18 Phase of Construction Project Stormwater BMPs Date Wet/Dry Season TBD TBD TBD TBD 19 Element 13: Protect Low Impact Development (LID) BMPs (2.1.13). Infiltration trenches are proposed. Care should be taken to ensure heavy machinery does not compact areas for future infiltration in order to maintain the infiltration capacity of existing soils. 20 Pollution Prevention Team (3.0) Table 7 – Team Information Title Name(s) Phone Number Certified Erosion and Sediment Control Lead (CESCL) TBD Resident Engineer Ben Enfield (360) 292-7230 Emergency Ecology Contact Northwest Regional Office (425) 649-7000 Emergency Permittee/ Owner Contact TBD Non-Emergency Owner Contact TBD Monitoring Personnel TBD Ecology Regional Office Northwest Regional Office (425) 649-7000 21 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 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 Blank form under Appendix D. 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. Discharge will be to groundwater onsite. Stormwater Quality Sampling (4.2) N/A Turbidity Sampling (4.2.1) No offsite discharge is expected and therefore on site sampling is assumed to be required. If offsite discharge of stormwater does occur then monitoring shall be implemented. 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) x 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. 22 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 · Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish, Whatcom): (425) 649-7000 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. 23 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 9 – pH Sampling Method pH meter X pH test kit Wide range pH indicator paper 24 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies (5.0) 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. 25 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. 26 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. To sign up for WQWebDMR go to: https://www.ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Water-quality- permits-guidance/WQWebPortal-guidance 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. Specific information to be included in the noncompliance report is found in Special Condition S5.F.3 of the CSWGP. 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. · Northwest Region at (425) 649-7000 for Island, King, Kitsap, San Juan, Skagit, Snohomish, or Whatcom County 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 A Site Map X XXXXXXXXXXXXXXXXXXXXXXXX PERMITTING SUBMITTALA B C D E F G H 1 2 3 4 5 6 Yelm High School Yelm WA Yelm HS Soccer Field Conversion and Tennis Courts Reconstruction R Call 811 two business days before you dig 4405 7th Ave. SE, Suite 203 Lacey, WA 98503 360.456.3813 bob@rwdroll.com 0 SCALE: 1"=30' 15'30'45'60' DEMOLITION & TESC PLAN D1.0 GRUB AND STRIP TOPSOIL, 6" MIN. (95,030 ± SF) DEMOLISH EXISTING CONCRETE (40 ± SF) DEMOLISH EXISTING ASPHALT (14,290 ± SF) STABILIZED CONSTRUCTION ENTRANCE (1200 ± SF) DEMOLISH EXISTING TENNIS COURT SURFACING (39,800 ± SF) TEMPORARY SECURITY FENCING SILT FENCE DEMOLISH EXISTING CONCRETE CURB (± 40 LF) CLEAR AND GRUB ( 5,430 ± SF) DEMOLITION LEGEND X 1.EXISTING SUBSURFACE DRAINAGE TO BE ABANDONED IN PLACE 2.EXISTING IRRIGATION HEADS TO BE SALVAGED AND RETURNED TO OWNER, IRRIGATION LATERALS TO BE CAPPED AND ABANDONED IN PLACE. 3.SALVAGE CONTROL VALVES AND RETURN TO OWNER. CUT AND CAP NIPPLE CONNECTING VALVE TO THE MAINLINE 4.EXISTING MAINLINE TO REMAIN, PRESERVE IN PLACE. 5.EXISTING ELECTRICAL LINES TO REMAIN. 6.EXISTING FIELD LIGHTS AND POWER JUNCTION BOXES TO REMAIN. 7.QUANTITIES PROVIDED FOR CONTRACTOR INFORMATION ONLY. CONTRACTOR TO DERIVE THEIR OWN QUANTITIES. 8.ANY DAMAGE SHALL BE REPAIRED IMMEDIATELY DEMOLITION NOTES INSTALL CATCH BASIN INLET PROTECTION REMOVE EXISTING CATCH BASIN INSTALL CATCH BASIN INLET PROTECTION DRINKING FOUNTAIN TO BE DEMOLISHED AND DISPOSED OFF SITE, WATER LINE TO BE USED FOR QUICK COUPLER CONNECTIONSREMOVE 10' CHAIN LINK FENCE AROUND TENNIS COURTS DEMOLISH 8' CHAIN LINK FENCE BETWEEN FIELD AND PARKING AREA SALVAGE EXISTING FABRIC FOR REINSTALLATION REMOVE 4' CHAIN LINK FENCE ALONG ROAD PRESERVE AND PROTECT EXISTING 8' CHAIN LINK FENCE ALONG EASTERN PROPERTY EDGE RELOCATE EXISTING CONEX BOX SOUTH OF TENNIS COURTS AS SHOWN ON SITE PLAN SAW CUT EXISTING ASPHALT 4 D1.1 4 D1.1 SILT FENCE TEMPORARY SECURITY FENCING 1 D1.1 2 D1.1 STABILIZED CONSTRUCTION ENTRANCE 3 D1.1 REMOVE EXISTING CONCRETE CURB PRESERVE AND PROTECT EX. JUNCTION BOX PRESERVE AND PROTECT EX. JUNCTION BOX PRESERVE AND PROTECT EX. 1" CONDUIT RELOCATE EXISTING CONEX BOX SOUTH OF TENNIS COURTS AS SHOWN ON SITE PLAN DEMOLISH EXISTING GATE APPENDIX B BMP Detail BMP C101: Preserving Natural Vegetation Purpose The purpose of preserving natural vegetation is to reduce erosion wherever practicable. Limiting site disturbance is the single most effective method for reducing erosion. For example, conifers can hold up to about 50 percent of all rain that falls during a storm. Up to 20-30 percent 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 local governments. 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. 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 governments 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 results 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 prob- lems although sensitivity between species does vary and should be checked. Trees can typ- ically 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 dry well 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 271 around the tree trunk. The system should then be covered with small stones to allow air to cir- culate 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 2-3 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 undis- turbed, 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, power, water, and 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 with a few specific trees are: 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 hemlock 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 272 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 (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 natural swales and they can incorporate them into the natural landscaping of an area. Do not use critical-areas 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: 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 permitting authority. These should not be disturbed and must protected with sediment control BMPs to prevent impacts. The local permitting authority may expand the buffer widths temporarily to allow the use of the expan- ded area for removal of sediment. Vegetative Buffer Zones - areas that may be identified in undisturbed vegetation areas or managed vegetation areas that are outside any Designated Critical Area Buffer. They may be utilized to provide an additional sediment control area and/or reduce runoff velocities. If being used for pre- servation of natural vegetation, they should be arranged in clumps or strips. They can be used to pro- tect natural swales and incorporated into the natural landscaping area. Design and Installation Specifications l Preserving natural vegetation or plantings in clumps, blocks, or strips is generally the easiest and most successful method. l Leave all unstable steep slopes in natural vegetation. l Mark clearing limits and keep all equipment and construction debris out of the natural areas and buffer zones. Steel construction fencing is the most effective method to protect sensitive areas and buffers. Alternatively, wire-backed silt fence on steel posts is marginally effective. Flagging alone is typically not effective. l Keep all excavations outside the dripline of trees and shrubs. l Do not push debris or extra soil into the buffer zone area because it will cause damage by 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 273 burying and smothering vegetation. l Vegetative buffer zones for streams, lakes or other waterways shall be established by the local permitting authority or other state or federal permits or approvals. Maintenance Standards Inspect the area frequently to make sure flagging remains in place and the area remains undis- turbed. Replace all damaged flagging immediately. Remove all materials located in the buffer area that may impede the ability of the vegetation to act as a filter. BMP C103: High-Visibility Fence Purpose High-visibility fencing is intended to: l Restrict clearing to approved limits. l Prevent disturbance of sensitive areas, their buffers, and other areas required to be left undis- turbed. l Limit construction traffic to designated construction entrances, exits, or internal roads. l Protect areas where marking with survey tape may not provide adequate protection. 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 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-visibility fence. Silt fence shall be at least 3 feet high and must be highly visible to meet the requirements 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 274 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 sta- bilized 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 construction 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 res- idence, rather than only at the main subdivision entrance. Stabilized surfaces shall be of sufficient length/width to provide vehicle access/parking, based on lot size and configuration. On large commercial, highway, and road projects, the designer should include enough extra mater- ials in the contract to allow for additional stabilized accesses not shown in the initial Construction 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 See Figure II-3.1: 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 configuration of the site does not allow the full length (100’). 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 con- crete, 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. A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into the rock pad. The geotextile shall meet the standards listed in Table II-3.2: Stabilized Con- struction Access Geotextile Standards. Geotextile Property Required Value Grab Tensile Strength (ASTM D4751)200 psi min. Table II-3.2: Stabilized Construction Access Geotextile Standards 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 275 Geotextile Property Required Value Grab Tensile Elongation (ASTM D4632)30% max. Mullen Burst Strength (ASTM D3786-80a)400 psi min. AOS (ASTM D4751)20-45 (U.S. standard sieve size) Table II-3.2: Stabilized Construction Access Geotextile Standards (continued) 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 stabilized access. During large concrete pours, excess concrete is often available for this purpose. 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 maintenance. 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 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 per- formance testing to verify operation of this new specification. 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 Stand- ard 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-3.3: Stabilized Construction Access Alternative Material Requirements. Sieve Size Percent Passing 2½″99-100 Table II-3.3: Stabilized Construction Access Alternative Material Requirements 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 276 Sieve Size Percent Passing 2″65-100 ¾″40-80 No. 4 5 max. No. 100 0-2 % Fracture 75 min. Table II-3.3: Stabilized Construction Access Alternative Material Requirements (continued) l All percentages are by weight. l The sand equivalent value and dust ratio requirements do not apply. l The fracture requirement shall be at least one fractured face and will apply the combined aggregate retained on the No. 4 sieve in accordance with FOP for AASHTO T 335. 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 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 pavement shall not be cleaned by washing down the street, except when high efficiency sweeping is inef- fective and there is a threat to public safety. If it is necessary to wash the streets, the con- struction 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 effi- ciency mechanical sweeper because this creates dust and throws soils into storm systems 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 277 l Upon project completion and site stabilization, all construction accesses intended as per- manent access for maintenance shall be permanently stabilized. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 278 Figure II-3.1: Stabilized Construction Access 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 279 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 jurisdictions may choose not to accept these products, or may require additional testing prior to consideration 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 C106: Wheel Wash Purpose Wheel washes reduce the amount of sediment transported onto paved roads by washing dirt from the wheels of motor vehicles prior to the motor vehicles leaving the construction site. Conditions of Use l Use a wheel wash when BMP C105: Stabilized Construction Access is not preventing sed- iment from being tracked off site. l Wheel washing is generally an effective BMP when installed with careful attention to topo- graphy. For example, a wheel wash can be detrimental if installed at the top of a slope abut- ting a right-of-way where the water from the dripping truck can run unimpeded into the street. l Pressure washing combined with an adequately sized and surfaced pad with direct drainage to a large 10-foot x 10-foot sump can be very effective. l Wheel wash wastewater is not stormwater. It is commonly called process water, and must be discharged to a separate on-site treatment system that prevents discharge to waters of the State, or to the sanitary sewer with local sewer district approval. l Wheel washes may use closed-loop recirculation systems to conserve water use. l Wheel wash wastewater shall not include wastewater from concrete washout areas. l When practical, the wheel wash should be placed in sequence with BMP C105: Stabilized Construction Access. Locate the wheel wash such that vehicles exiting the wheel wash will enter directly onto BMP C105: Stabilized Construction Access. In order to achieve this, BMP C105: Stabilized Construction Access may need to be extended beyond the standard install- ation to meet the exit of the wheel wash. Design and Installation Specifications Suggested details are shown in Figure II-3.2: Wheel Wash. The Local Permitting Authority may allow other designs. A minimum of 6 inches of asphalt treated base (ATB) over crushed base mater- ial or 8 inches over a good subgrade is recommended to pave the wheel wash. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 280 Use a low clearance truck to test the wheel wash before paving. Either a belly dump or lowboy will work well to test clearance. Keep the water level from 12 to 14 inches deep to avoid damage to truck hubs and filling the truck tongues with water. Midpoint spray nozzles are only needed in extremely muddy conditions. Wheel wash systems should be designed with a small grade change, 6- to 12-inches for a 10-foot- wide pond, to allow sediment to flow to the low side of pond to help prevent re-suspension of sed- iment. A drainpipe with a 2- to 3-foot riser should be installed on the low side of the pond to allow for easy cleaning and refilling. Polymers may be used to promote coagulation and flocculation in a closed-loop system. Polyacrylamide (PAM) added to the wheel wash water at a rate of 0.25 - 0.5 pounds per 1,000 gallons of water increases effectiveness and reduces cleanup time. If PAM is already being used for dust or erosion control and is being applied by a water truck, the same truck can be used to change the wash water. Maintenance Standards The wheel wash should start out each day with fresh water. The wheel wash water should be changed a minimum of once per day. On large earthwork jobs where more than 10-20 trucks per hour are expected, the wheel wash water will need to be changed more often. 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 jurisdictions may choose not to accept these products, or may require additional testing prior to consideration 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 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 281 Figure II-3.2: Wheel Wash 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 282 BMP C107: Construction Road / Parking Area Stabilization Purpose Stabilizing roads, parking areas, and other on-site vehicle transportation routes immediately after grading reduces erosion caused by construction traffic or stormwater runoff. Conditions of Use Roads and parking areas shall be stabilized wherever they are constructed, whether permanent or temporary, for use by construction traffic. BMP C103: High-Visibility Fence shall be installed, if necessary, to limit the access of vehicles to only those roads and parking areas that are stabilized. Design and Installation Specifications l On areas that will receive asphalt as part of the project, install the first lift as soon as possible. l A 6-inch depth of 2- to 4-inch crushed rock, gravel base, or crushed surfacing base course shall be applied immediately after grading or utility installation. A 4-inch course of asphalt treated base (ATB) may also be used, or the road/parking area may be paved. It may also be possible to use cement or calcium chloride for soil stabilization. If cement or cement kiln dust is used for roadbase stabilization, pH monitoring and BMP C252: Treating and Disposing of High pH Water is necessary to evaluate and minimize the effects on stormwater. If the area will not be used for permanent roads, parking areas, or structures, a 6-inch depth of hog fuel may also be used, but this is likely to require more maintenance. Whenever possible, con- struction roads and parking areas shall be placed on a firm, compacted subgrade. l Temporary road gradients shall not exceed 15 percent. Roadways shall be carefully graded to drain. Drainage ditches shall be provided on each side of the roadway in the case of a crowned section, or on one side in the case of a super-elevated section. Drainage ditches shall be directed to a sediment control BMP. l Rather than relying on ditches, it may also be possible to grade the road so that runoff sheet- flows into a heavily vegetated area with a well-developed topsoil. Landscaped areas are not adequate. If this area has at least 50 feet of vegetation that water can flow through, then it is generally preferable to use the vegetation to treat runoff, rather than a sediment pond or trap. The 50 feet shall not include wetlands or their buffers. If runoff is allowed to sheetflow through adjacent vegetated areas, it is vital to design the roadways and parking areas so that no con- centrated runoff is created. l Storm drain inlets shall be protected to prevent sediment-laden water entering the drainage system (see BMP C220: Inlet Protection). Maintenance Standards Inspect stabilized areas regularly, especially after large storm events. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 283 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 Use seeding throughout the project on disturbed areas that have reached final grade or that will remain unworked for more than 30 days. The optimum seeding windows for western Washington are April 1 through June 30 and September 1 through October 1. Between July 1 and August 30 seeding requires irrigation until 75 percent grass cover is established. Between October 1 and March 30 seeding requires a cover of mulch or an erosion control blanket until 75 percent grass cover is established. 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 pro- tection. 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. Seed and mulch all disturbed areas not otherwise vegetated at final site stabilization. Final sta- bilization means the completion of all soil disturbing activities at the site and the establishment 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. Design and Installation Specifications General l Install channels intended for vegetation before starting major earthwork and hydroseed with a Bonded Fiber Matrix. For vegetated channels that will have high flows, install erosion control blankets over the top of hydroseed. Before allowing water to flow in vegetated channels, establish 75 percent vegetation cover. If vegetated channels cannot be established by seed 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 284 before water flow; install sod in the channel bottom — over top of hydromulch and erosion con- trol blankets. l Confirm the installation of all required surface water control measures to prevent seed from washing away. l Hydroseed applications shall include a minimum of 1,500 pounds per acre of mulch with 3 per- cent 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 Quality 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 Enhance vegetation establishment by dividing the hydromulch operation into two phases: o Phase 1- Install all seed and fertilizer with 25-30 percent mulch and tackifier onto soil in the first lift. o Phase 2- Install the rest of the mulch and tackifier over the first lift. Or, enhance vegetation by: o Installing the mulch, seed, fertilizer, and tackifier in one lift. o Spread or blow straw over the top of the hydromulch at a rate of 800-1000 pounds per acre. o Hold straw in place with a standard tackifier. Both of these approaches will increase cost moderately but will greatly improve and enhance vegetative establishment. The increased cost may be offset by the reduced need for: o Irrigation. o Reapplication of mulch. o Repair of failed slope surfaces. This technique works with standard hydromulch (1,500 pounds per acre minimum) and Bon- ded Fiber Matrix/ Mechanically Bonded Fiber Matrix (BFM/MBFMs) (3,000 pounds per acre minimum). l Seed may be installed by hand if: o Temporary and covered by straw, mulch, or topsoil. o Permanent in small areas (usually less than 1 acre) and covered with mulch, topsoil, or erosion blankets. l The seed mixes listed in Table II-3.4: Temporary and Permanent Seed Mixes include 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 285 recommended mixes for both temporary and permanent seeding. l Apply these mixes, 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. l Consult the local suppliers or the local conservation district for their recommendations. The appropriate mix depends on a variety of factors, including location, exposure, soil type, slope, and expected foot traffic. Alternative seed mixes approved by the local authority may be used, depending on the soil type and hydrology of the area. 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-Festuca arundin-75-80 98 90 Table II-3.4: Temporary and Permanent Seed Mixes 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 286 Common Name Latin Name % Weight % Purity % Germination cue acea or Festuca elatior Seaside/Creeping bentgrass Agrostis palustris 10-15 92 85 Redtop bentgrass Agrostis alba or Agrostis gigantea 5-10 90 80 Wet Area Seed Mix 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 praten- sis 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 col- onization by native plants is desirable. Likely applications include rural road and utility right-of-way. Seed- ing 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-3.4: Temporary and Permanent Seed Mixes (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, 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 287 permanent areas shall use soil amendments to achieve organic matter and permeability per- formance defined in engineered soil/landscape systems. For systems that are deeper than 8 inches complete the rototilling process in multiple lifts, or prepare the engineered soil system per specifications and place to achieve the specified depth. Fertilizers l Conducting soil tests to determine the exact type and quantity of fertilizer is recommended. This will prevent the over-application 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. Always use slow-release fertilizers because they are more efficient and have fewer environmental impacts. Do not add fertilizer to the hydromulch machine, or agit- ate, more than 20 minutes before use. Too much agitation destroys the slow-release coating. l There are numerous products available that take the place of chemical fertilizers. These include several with seaweed extracts that are beneficial to soil microbes and organisms. If 100 percent cottonseed meal is used as the mulch in hydroseed, chemical fertilizer may not be necessary. Cottonseed meal provides a good source of long-term, slow-release, available nitrogen. 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 percent tackifier. Achieve a minimum of 95 percent soil coverage during application. 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 fertilizer. 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: 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 288 Maintenance Standards Reseed any seeded areas that fail to establish at least 75 percent cover (100 percent cover for areas that receive sheet or concentrated flows). If reseeding is ineffective, use an alternate method such as sodding, mulching, nets, or blankets. l Reseed and protect by mulch any areas that experience erosion after achieving adequate cover. Reseed and protect by mulch any eroded area. l Supply seeded areas with adequate moisture, but do not water to the extent that it causes run- off. 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 jurisdictions may choose not to accept these products, or may require additional testing prior to consideration 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 moderating 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; 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 289 BMP C140: Dust Control Purpose Dust control prevents wind transport of dust from disturbed soil surfaces onto roadways, drainage ways, and 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 ways, or surface waters are likely. Design and Installation Specifications l Vegetate or mulch areas that will not receive vehicle traffic. In areas where planting, mulching, 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 enclos- ures 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 sup- pressant. Local governments may approve other dust palliatives such as calcium chloride 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 effect- ive than water alone. This is due to increased infiltration of water into the soil and reduced evaporation. In addition, small soil particles are bonded together and are not as easily trans- ported 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 application 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. l Contact your local Air Pollution Control Authority for guidance and training on other dust con- trol measures. Compliance with the local Air Pollution Control Authority constitutes 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 313 compliance with this BMP. 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 recon- struction. 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-causing 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. Hav- ing 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 require- ments. In addition, contractors can save money by buying some materials in bulk and storing them at their office or yard. Conditions of Use l Construction projects of any size or type can benefit from having materials on hand. A small commercial development project could have a roll of plastic and some gravel available for immediate protection of bare soil and temporary berm construction. A large earthwork project, such as highway construction, might have several tons of straw, several rolls of plastic, flexible 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 314 pipe, sandbags, geotextile fabric and steel “T” posts. l Materials should be stockpiled and readily available before any site clearing, grubbing, or earthwork begins. A large contractor or project proponent could keep a stockpile of materials that are available for use on several projects. l If storage space at the project site is at a premium, the contractor could maintain the materials at their office or yard. The office or yard must be less than an hour from the project site. Design and Installation Specifications Depending on project type, size, complexity, and length, materials and quantities will vary. A good minimum list of items that will cover numerous situations includes: l Clear Plastic, 6 mil l Drainpipe, 6 or 8 inch diameter l Sandbags, filled l Straw Bales for mulching l Quarry Spalls l Washed Gravel l Geotextile Fabric l Catch Basin Inserts l Steel "T" Posts l Silt fence material l Straw Wattles Maintenance Standards l All materials with the exception of the quarry spalls, steel “T” posts, and gravel should be kept covered and out of both sun and rain. l Re-stock materials as needed. BMP C151: Concrete Handling Purpose Concrete work can generate process water and slurry that contain fine particles and high pH, both of which can violate water quality standards in the receiving water. Concrete spillage or concrete dis- charge to waters of the State is prohibited. Use this BMP to minimize and eliminate concrete, con- crete process water, and concrete slurry from entering waters of the State. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 315 Conditions of Use Any time concrete is used, utilize these management practices. Concrete construction project com- ponents include, but are not limited to: l Curbs l Sidewalks l Roads l Bridges l Foundations l Floors l Runways Disposal options for concrete, in order of preference are: 1. Off-site disposal 2. Concrete wash-out areas (see BMP C154: Concrete Washout Area) 3. De minimus washout to formed areas awaiting concrete Design and Installation Specifications l Wash concrete truck drums at an approved off-site location or in designated concrete washout areas only. Do not wash out concrete trucks onto the ground (including formed areas awaiting concrete), or into storm drains, open ditches, streets, or streams. Refer to BMP C154: Concrete Washout Area for information on concrete washout areas. o Return unused concrete remaining in the truck and pump to the originating batch plant for recycling. Do not dump excess concrete on site, except in designated concrete washout areas as allowed in BMP C154: Concrete Washout Area. l Wash small concrete handling equipment (e.g. hand tools, screeds, shovels, rakes, floats, trowels, and wheelbarrows) into designated concrete washout areas or into formed areas awaiting concrete pour. 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 dir- ectly 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 316 l Always use forms or solid barriers for concrete pours, such as pilings, within 15-feet of surface 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 contains fine particles and 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 through sawcutting or surfacing from enter- ing 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: l Sawing l Coring l Grinding l Roughening l Hydro-demolition l Bridge and road surfacing 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 317 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 ground water or sur- face water quality standards. l Do not allow process water generated during hydro-demolition, surface roughening or similar operations to drain to any natural or constructed drainage conveyance including stormwater systems. Dispose of process water in a manner that does not violate ground water 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 watercourses from material delivery and storage. Minimize the storage of hazardous materials on-site, store mater- ials in a designated area, and install secondary containment. 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 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 318 l Hazardous chemicals such as acids, lime, adhesives, paints, solvents, and curing compounds 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 (Oct 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 con- crete 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 rainwater 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 capa- city of the largest container within its boundary, whichever is greater. l Secondary containment facilities shall be impervious to the materials stored therein for a min- imum 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, prior to and during rain events. 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: 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 319 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-Pair 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: 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 320 Design and Installation Specifications Implementation l Perform washout of concrete truck drums at an approved off-site location or in designated con- crete 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 dir- ectly 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 con- crete supplier before any deliveries are made. l Educate employees and subcontractors on the concrete waste management techniques described in this BMP. 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 subcontractor agreements. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 321 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 acci- dental 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 mul- tiple 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. 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 con- crete work. l Once concrete wastes are washed into the designated washout area and allowed to harden, 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 322 the concrete should be broken up, removed, and disposed of per applicable solid waste reg- ulations. Dispose of hardened concrete on a regular basis. l During periods of concrete work, inspect the concrete washout areas daily to verify continued 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 pre- cipitation. l Remove and dispose of hardened concrete and return the structure to a functional con- dition. 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. 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 323 Figure II-3.7: Concrete Washout Area with Wood Planks 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 324 Figure II-3.8: Concrete Washout Area with Straw Bales 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 325 Figure II-3.9: Prefabricated Concrete Washout Container w/Ramp 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 326 Maintenance Standards Replace riprap as needed. BMP C203: Water Bars Purpose A water bar is a small ditch or ridge of material that is constructed diagonally across a road or right- of-way to divert stormwater runoff from the road surface, wheel tracks, or a shallow road ditch. See Figure II-3.12: Water Bar. Conditions of Use Clearing right-of-way and construction of access for power lines, pipelines, and other similar install- ations often require long narrow right-of-ways over sloping terrain. Disturbance and compaction pro- motes gully formation in these cleared strips by increasing the volume and velocity of runoff. Gully formation may be especially severe in tire tracks and ruts. To prevent gullying, runoff can often be diverted across the width of the right-of-way to undisturbed areas by using small predesigned diver- sions. Give special consideration to each individual outlet area, as well as to the cumulative effect of added diversions. Use gravel to stabilize the diversion where significant vehicular traffic is anticipated. Design and Installation Specifications l Height: 8-inch minimum, measured from the channel bottom to the ridge top. l Side slope of channel: 2H:1V maximum; 3H:1V or flatter when vehicles will cross. l Top width of ridge: 6-inch minimum. l Locate water bars to use natural drainage systems and to discharge into well vegetated stable areas. l See Table II-3.9: Water Bar Spacing Guidelines: Slope Along Road (%)Spacing (ft) < 5 125 5 - 10 100 10 - 20 75 20 - 35 50 > 35 Use rock lined ditch Table II-3.9: Water Bar Spacing Guidelines 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 338 l Grade of water bar and angle: Select an angle that results in a ditch slope less than 2 percent. l Install the water bar as soon as the clearing and grading is complete. When utilities are being installed, reconstruct the water bar as construction is complete in each section. l Compact the water bar ridge. l Stabilize, seed, and mulch the portions that are not subject to traffic. Gravel the areas crossed by vehicles. l Note that BMP C208: Triangular Silt Dike (TSD) can be used to create the ridge for the water bar. Maintenance Standards Periodically inspect water bars after every heavy rainfall for wear and erosion damage. l Immediately remove sediment from the flow area and repair the dike. l Check outlet areas and make timely repairs as needed. l When permanent road drainage is established and the area above the temporary water bar is permanently stabilized, remove the dikes and fill the channel to blend with the natural ground, and appropriately stabilize the disturbed area. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 339 Figure II-3.12: Water Bar 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 340 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 Depart- ment of Fish and Wildlife. See I-2.11 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-3.10: Storm Drain Inlet Protection lists several options for inlet protection. All of the methods for inlet protection tend to plug and require a high frequency of maintenance. Limit contributing drain- age 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 356 Type of Inlet Pro- tection Emergency Overflow Applicable for Paved/ Earthen Sur- faces 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-3.10: 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 installation spe- cifications for excavated drop inlet protection include: l Provide a depth of 1-2 ft as measured from the crest of the inlet structure. l Slope sides 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 357 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-3.17: Block and Gravel Filter. Design and installation specifications for block gravel fil- ters 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 open- ing. 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 ½-inch openings over all block openings. 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 stone area between the gravel berm and the inlet. o Use stones 3 inches in diameter or larger on the upstream slope of the berm. o Use gravel ½- to ¾-inch at a minimum thickness of 1-foot on the downstream slope of the berm. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 358 Figure II-3.17: Block and Gravel Filter 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 359 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 ½-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 install- ation 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 protection with wooden weirs include: l Use wire mesh with ½-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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 360 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-3.18: Block and Gravel Curb Inlet Protection. Design and installation spe- cifications for block and gravel curb inlet protection include: l Use wire mesh with ½-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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 361 Figure II-3.18: Block and Gravel Curb Inlet Protection 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 362 Curb and Gutter Sediment Barrier 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-3.19: Curb and Gutter Barrier. Design and installation specifications for curb and gutter sediment barrier 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 363 Figure II-3.19: Curb and Gutter Barrier 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 364 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 jurisdictions may choose not to accept these products, or may require additional testing prior to consideration 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 sub- stantial amounts of overland flow. Any concentrated flows must be directed to a sediment trap- ping 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). l Filter fabric (geotextile) may be anchored over the brush berm to enhance the filtration ability of the barrier. Ten-ounce burlap is an adequate alternative to filter fabric. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 365 BMP C233: Silt Fence Purpose Silt fence reduces 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 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 370 Figure II-3.22: Silt Fence 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 371 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-3.11: 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-3.11: 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 minimum of six months of expected usable construction life at a temperature range of 0°F to 120°F. l One-hundred percent 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-3.22: 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. 2. Construct silt fences in areas of clearing, grading, or drainage prior to starting those activities. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 372 3. The silt fence shall have a 2-feet min. and a 2½-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 sections 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 geotextile 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 polymeric mesh must be as resistant to the same level of ultraviolet radiation as the geotextile fabric it supports. 8. Bury the bottom of the geotextile fabric 4-inches min. below the ground surface. Backfill 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 polymeric 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 cannot 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 pre- vent 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 either: 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. 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, 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 373 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-3.23: 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 standard 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 374 Figure II-3.23: Silt Fence Installation by Slicing Method 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 375 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- 3.12: Contributing Drainage Area for Vegetated Strips): Average Contributing Area Slope Average Contributing Area Per- cent Slope Max 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-3.12: Contributing Drainage Area for Vegetated Strips 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 376 Design and Installation Specifications l The vegetated strip shall consist of a continuous strip of dense vegetation with topsoil for a min- imum of a 25-foot length along the flowpath. Grass-covered, landscaped areas are generally not adequate because the volume of sediment overwhelms the grass. Ideally, vegetated 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 pro- tected 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, storm- water runoff controls must be installed to reduce the flows entering the vegetated strip, or addi- tional 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 sed- iment. Conditions of Use 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 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 effect- ive for one to two seasons. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 377 l Prevent rilling beneath wattles by entrenching and overlapping wattles to prevent water from passing between them. Design Criteria l See Figure II-3.24: 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 constructed 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 min. 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 pro- truding above the wattle. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 378 Figure II-3.24: Wattles 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 379 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 jurisdictions may choose not to accept these products, or may require additional testing prior to consideration 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 sys- tem with surface intake. Vegetative filtration improves turbidity levels of stormwater discharges by fil- tering runoff through existing vegetation where undisturbed forest floor duff layer or established lawn with thatch layer are present. Vegetative filtration can also be used to infiltrate dewatering waste from foundations, vaults, and trenches as long as runoff does not occur. Conditions of Use l For every five acres of disturbed soil use one acre of grass field, farm pasture, or wooded area. Reduce or increase this area depending on project size, ground water 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 ground water table, or in areas that will have a high seasonal ground water 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. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 380 system) will be directed into the permanent Flow Control BMP. If site constraints make locating the untreated stormwater storage pond difficult, the permanent Flow Control BMP may be divided to serve as the untreated stormwater storage pond and the post-treatment temporary flow control pond. A berm or barrier must be used in this case so the untreated water does not mix with the treated water. Both untreated stormwater storage requirements, and adequate post-treatment flow control must be achieved. The designer must document in the Construction SWPPP how the per- manent Flow Control BMP is able to attenuate the discharge from the site to meet the requirements of Element 3: Control Flow Rates. If the design of the permanent Flow Control BMP was modified for temporary construction flow control purposes, the construction of the permanent Flow Control BMP must be finalized, as designed for its permanent function, at project completion. Maintenance Standards l Rapid sand filters typically have automatic backwash systems that are triggered by a pre-set pressure drop across the filter. If the backwash water volume is not large or substantially more turbid than the untreated stormwater stored in the holding pond or tank, backwash return to the untreated stormwater pond or tank may be appropriate. However, other means of treat- ment and disposal may be necessary. l Screen, bag, and fiber filters must be cleaned and/or replaced when they become clogged. l Sediment shall be removed from the storage and/or treatment ponds as necessary. Typically, sediment removal is required once or twice during a wet season and at the decommissioning of the ponds. l Disposal of filtration equipment must comply with applicable local, state, and federal reg- ulations. BMP C252: Treating and Disposing of High pH Water Purpose When pH levels in stormwater rise above 8.5, it is necessary to lower the pH levels to the acceptable range of 6.5 to 8.5 prior to discharge to surface or ground water. A pH level range of 6.5 to 8.5 is typ- ical for most natural watercourses, and this neutral pH range is required for the survival of aquatic organisms. Should the pH rise or drop out of this range, fish and other aquatic organisms may become stressed and may die. Conditions of Use l The water quality standard for pH in Washington State is in the range of 6.5 to 8.5. Storm- water with pH levels exceeding water quality standards may be either neutralized on site or disposed of to a sanitary sewer or concrete batch plant with pH neutralization capabilities. l Neutralized stormwater may be discharged to surface waters under the Construction Storm- water General permit. l Neutralized process water such as concrete truck wash-out, hydro-demolition, or saw-cutting slurry must be managed to prevent discharge to surface waters. Any stormwater 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 406 contaminated during concrete work is considered process wastewater and must not be dis- charged to waters of the State or stormwater collection systems. l The process used for neutralizing and/or disposing of high pH stormwater from the site must be documented in the Construction Stormwater Pollution Prevention Plan. Causes of High pH High pH at construction sites is most commonly caused by the contact of stormwater with poured or recycled concrete, cement, mortars, and other Portland cement or lime containing construction materials. (See BMP C151: Concrete Handling for more information on concrete handling pro- cedures). The principal caustic agent in cement is calcium hydroxide (free lime). Calcium hardness can contribute to high pH values and cause toxicity that is associated with high pH conditions. A high level of calcium hardness in waters of the state is not allowed. Ground water stand- ard for calcium and other dissolved solids in Washington State is less than 500 mg/l. Treating High pH Stormwater by Carbon Dioxide Sparging Advantages of Carbon Dioxide Sparging l Rapidly neutralizes high pH water. l Cost effective and safer to handle than acid compounds. l CO2 is self-buffering. It is difficult to overdose and create harmfully low pH levels. l Material is readily available. The Chemical Process of Carbon Dioxide Sparging When carbon dioxide (CO2) is added to water (H 2O), carbonic acid (H2CO3) is formed which can further dissociate into a proton (H+) and a bicarbonate anion (HCO3-) as shown below: CO2 + H 2O ↔ H2CO3 ↔ H+ + HCO3- The free proton is a weak acid that can lower the pH. Water temperature has an effect on the reac- tion as well. The colder the water temperature is, the slower the reaction occurs. The warmer the water temperature is, the quicker the reaction occurs. Most construction applications in Washington State have water temperatures in the 50°F or higher range so the reaction is almost simultaneous. The Treatment Process of Carbon Dioxide Sparging High pH water may be treated using continuous treatment, continuous discharge systems. These manufactured systems continuously monitor influent and effluent pH to ensure that pH values are within an acceptable range before being discharged. All systems must have fail safe automatic shut off switches in the event that pH is not within the acceptable discharge range. Only trained operators may operate manufactured systems. System manufacturers often provide trained operators or train- ing on their devices. The following procedure may be used when not using a continuous discharge system: 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 407 1. Prior to treatment, the appropriate jurisdiction should be notified in accordance with the reg- ulations set by the jurisdiction. 2. Every effort should be made to isolate the potential high pH water in order to treat it separately from other stormwater on-site. 3. Water should be stored in an acceptable storage facility, detention pond, or containment cell prior to pH treatment. 4. Transfer water to be treated for pH to the pH treatment structure. Ensure that the pH treat- ment structure size is sufficient to hold the amount of water that is to be treated. Do not fill the pH treatment structure completely, allow at least 2 feet of freeboard. 5. The operator samples the water within the pH treatment structure for pH and notes the clarity of the water. As a rule of thumb, less CO2 is necessary for clearer water. The results of the samples and water clarity observations should be recorded. 6. In the pH treatment structure, add CO2 until the pH falls into the range of 6.9-7.1. Adjusting pH to within 0.2 pH units of receiving water (background pH) is recommended. It is unlikely that pH can be adjusted to within 0.2 pH units using dry ice. Compressed carbon dioxide gas should be introduced to the water using a carbon dioxide diffuser located near the bottom of the pH treatment structure, this will allow carbon dioxide to bubble up through the water and diffuse more evenly. 7. Slowly discharge the water, making sure water does not get stirred up in the process. Release about 80% of the water from the pH treatment structure leaving any sludge behind. If turbidity remains above the maximum allowable, consider adding filtration to the treatment train. See BMP C251: Construction Stormwater Filtration. 8. Discharge treated water through a pond or drainage system. 9. Excess sludge needs to be disposed of properly as concrete waste. If several batches of water are undergoing pH treatment, sludge can be left in the treatment structure for the next batch treatment. Dispose of sludge when it fills 50% of the treatment structure volume. 10. Disposal must comply with applicable local, state, and federal regulations. Treating High pH Stormwater by Food Grade Vinegar Food grade vinegar that meets FDA standards may be used to neutralize high pH water. Food grade vinegar is only 4% to 18% acetic acid with the remainder being water. Food grade vinegar may be used if dosed just enough to lower pH sufficiently. Use a treatment process as described above for CO2 sparging, but add food grade vinegar instead of CO2. This treatment option for high pH stormwater does not apply to anything but food grade vinegar. Acetic acid does not equal vinegar. Any other product or waste containing acetic acid must go through the evaluation process in Appendix G of Whole Effluent Toxicity Testing Guidance and Test Review Criteria (Marshall, 2016). 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 408 Disposal of High pH Stormwater Sanitary Sewer Disposal Local sewer authority approval is required prior to disposal via the sanitary sewer. Concrete Batch Plant Disposal l Only permitted facilities may accept high pH water. l Contact the facility to ensure they can accept the high pH water. Maintenance Standards Safety and materials handling: l All equipment should be handled in accordance with OSHA rules and regulations. l Follow manufacturer guidelines for materials handling. Each operator should provide: l A diagram of the monitoring and treatment equipment. l A description of the pumping rates and capacity the treatment equipment is capable of treat- ing. Each operator should keep a written record of the following: l Client name and phone number. l Date of treatment. l Weather conditions. l Project name and location. l Volume of water treated. l pH of untreated water. l Amount of CO2 or food grade vinegar needed to adjust water to a pH range of 6.9-7.1. l pH of treated water. l Discharge point location and description. A copy of this record should be given to the client/contractor who should retain the record for three years. 2019 Stormwater Management Manual for Western Washington Volume II -Chapter 3 -Page 409 APPENDIX C Correspondence (Correspondence to be added to the appendix as received) APPENDIX D Site Inspection Form 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 APPENDIX E Construction Stormwater General Permit (CSWGP) Download the CSWGP: http://www.ecy.wa.gov/programs/wq/stormwater/construction/index.htm APPENDIX D Geotechnical Report Draft Technical Memorandum 500 Columbia St NW, Ste 110 • Olympia, WA 98501 • 360.791.3178 TO: FROM: DATE: RE: Robert Droll, President, RWD Landscape Architects Chad McMullen, PE, and Lance Levine, PE October 24, 2022 Summary of Geotechnical Engineering Services Yelm High School Soccer Field Conversion and Tennis Courts Reconstruction Yelm, Washington RWD Project No. 22041 Landau Project No. 1444018.010.011 Introduction This memorandum summarizes the results of geotechnical engineering services provided by Landau Associates, Inc. (Landau) in support of the Yelm High School Soccer Field Conversion and Tennis Courts Reconstruction project, located at 1315 West Yelm Avenue in Yelm, Washington (site; Figure 1). Services were provided in accordance with the scope outlined in Landau’s proposal, dated September 27, 2022. This memorandum has been prepared with information provided by RWD Landscape Architects (RWD, project landscape architect) and Yelm Community Schools (YCS, project owner) and with data collected during Landau’s geotechnical field exploration and laboratory testing programs. Project Understanding YCS proposes to resurface a grass-covered soccer field and rebuild six tennis courts in the northwest corner of the site. The soccer field will be resurfaced with synthetic turf. RWD retained Landau to complete a limited field investigation and develop infiltration recommendations for onsite stormwater infiltration. Site Conditions The total area of the existing soccer field and tennis courts measures approximately 370 feet (ft) by 400 ft. An asphalt-paved walkway wraps around the perimeter of the soccer field. The field and courts are generally flat and level. Topography to the west of the site slopes gently downward; a privately developed parcel east of the site is elevated 1 to 2 ft above the existing soccer field. Terrain to the north and south is flat and level. Relevant site features are shown on Figure 2. Geologic Setting Geologic information for the site and the surrounding area was obtained from the Washington Geologic Information Portal (DNR, accessed October 13, 2022). Surficial deposits at the site are mapped as Fraser- age continental glacial outwash gravels (Qgog), a unit that consists of predominantly sandy gravels and gravelly sand with cobbles and boulders. This material was deposited during the last glacial recession and has not been glacially overridden. DRAFT Landau Associates Summary of Geotechnical Engineering Services Soccer Field Conversion and Tennis Courts Reconstruction 2 October 24, 2022 A layer of topsoil was observed in Landau’s October 2022 explorations. The topsoil consisted of silty sand and compost overlying glacial soils; YCS staff stated that the topsoil was placed to help establish grass turf. Other soil conditions encountered in Landau’s explorations were consistent with the mapped geology for the site. Subsurface Explorations On October 5, 2022, YCS excavated four test pits (TP-1 through TP-4) 8.0 to 9.0 ft below ground surface (bgs). The approximate locations of the explorations are shown on Figure 2. Landau personnel coordinated and monitored the field explorations, collected representative soil samples, and maintained detailed logs of the subsurface soil and groundwater conditions observed. Subsurface conditions were described using the soil classification system shown on Figure 3, in general accordance with ASTM International (ASTM) standard D2488, Standard Practice for Description and Identification of Soils (Visual-Manual Procedures). Summary logs of the explorations are presented on Figures 4 through 7. Soil samples were transported to Landau’s geotechnical laboratory for further examination and testing. Natural moisture content determinations were performed on select soil samples in accordance with ASTM standard test method D2216, Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass. The natural moisture content is shown as “W = xx” (i.e., percentage of dry weight) in the “Test Data” column on Figures 4 through 7. Grain size analyses were performed on select soil samples in accordance with ASTM standard test method D6913, Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis. Samples selected for grain size analysis are designated with a “GS” in the “Test Data” column on Figures 4 through 7. Results of the grain size analyses are presented on Figure 8. Soil Conditions The soils observed in Landau’s October 2022 explorations were categorized into two units: • Topsoil: Topsoil was observed in all four test pits and consisted of grass turf over fine to medium sand with silt. The silty sand was mixed with compost to promote turf growth. The topsoil was in a loose, damp condition and extended 0.5 ft bgs. • Recessional Outwash: Recessional outwash was observed beneath the topsoil in all four test pits and consisted of sandy gravel with cobbles, of gravelly sand with cobbles, of gravelly sand with silt, and of fine to medium sand. Occasional boulders were observed in test pit TP-1. These variable soil gradations are typical of a sediment-choked, high-energy, braided river channel downstream of a receding glacier. The recessional outwash extended to the maximum depth explored. Groundwater Conditions Groundwater was not observed in Landau's October 2022 explorations, though soils were generally damp during test pit excavation. No seeps or pockets of moist or wet soil were observed. Mottling or other indicators of a seasonal high groundwater table were not observed. DRAFT Landau Associates Summary of Geotechnical Engineering Services Soccer Field Conversion and Tennis Courts Reconstruction 3 October 24, 2022 The groundwater conditions reported herein are for the specific date and locations indicated and may not be representative of other locations and/or times. Groundwater conditions will vary depending on local subsurface conditions, weather conditions, and other factors. Groundwater levels are expected to fluctuate seasonally, with maximum groundwater levels occurring during late winter and early spring. Conclusions and Recommendations Based on the subsurface conditions observed in Landau’s explorations, site soils are suitable for stormwater infiltration. Infiltration Rate Assessment The site is underlain by soils that will allow for moderate to rapid infiltration. Groundwater was not observed within the depths explored, and it is unlikely that infiltrated stormwater would mound above the groundwater table. Design infiltration rates were estimated using the results of Landau’s geotechnical laboratory tests (Figure 8) and the soil grain size method in the Washington State Department of Ecology’s 2019 Stormwater Management Manual for Western Washington (hereafter, 2019 SWMMWW). Correction factors were applied to account for site variability and the number of locations tested (CFv = 0.5), the test method (CFt = 0.4), and biofouling and siltation effects (CFm = 0.9). Landau used the simplified method to calculate design infiltration rates of 2.9 to 20 inches per hour, as shown in Table 1. (The 2019 SWMMWW limits infiltration rates to 20 inches per hour.) Table 1. Design Factored Infiltration Rates Exploration Designation Depth Range (ft bgs) Design Infiltration Rate (in/hr) TP-1 0.5–4.5 6.8 4.5–8 20(a) TP-2 0.5–1.5 6.8 1.5–8 20(a) TP-3 0.5–8 2.9 TP-4 0.5–1.5 2.9 1.5–5 15 5–8 20(a) (a) Maximum rate of 20 inches per hour. bgs = below ground surface ft = foot/feet in/hr = inches per hour DRAFT Landau Associates Summary of Geotechnical Engineering Services Soccer Field Conversion and Tennis Courts Reconstruction 4 October 24, 2022 Use of This Technical Memorandum Landau Associates has prepared this technical memorandum for the exclusive use of RWD Landscape Architects and Yelm Community Schools for specific application to the Yelm High School Soccer Field Conversion and Tennis Courts Reconstruction project in Yelm, Washington. No other party is entitled to rely on the information, conclusions, and recommendations included in this document without the express written consent of Landau Associates. Reuse of the information, conclusions, and recommendations provided herein for extensions of the project or for any other project, without review and authorization by Landau Associates, shall be at the user’s sole risk. Landau Associates warrants that, within the limitations of scope, schedule, and budget, its services have been provided in a manner consistent with that level of skill and care ordinarily exercised by members of the profession currently practicing in the same locality, under similar conditions as this project. Landau Associates makes no other warranty, either express or implied. Closing We trust that this memorandum provides you with the information needed to proceed with the project. If you have questions or comments, please contact Lance Levine at 360.628.5109 or at llevine@landauinc.com. LANDAU ASSOCIATES, INC. Chad McMullen, PE Senior Engineer Lance Levine, PE Senior Engineer CTM/LGL/SRW/mcs [\\OLYMPIA1\PROJECTS\1444\018.010\R\YHS SOCCER FIELD CONVERSION AND TENNIS COURTS RECONSTRUCTION DRAFT TECHNICAL MEMORANDUM 10.24.2022.DOCX] Attachments: Figure 1. Vicinity Map Figure 2. Site Exploration and Location Plan Figure 3. Soil Classification System and Key Figures 4–7. Logs of Test Pits TP-1 through TP-4 Figure 8. Grain Size Distribution DRAFT Landau Associates Summary of Geotechnical Engineering Services Soccer Field Conversion and Tennis Courts Reconstruction 5 October 24, 2022 References ASTM. 2017. Annual Book of ASTM Standards. In: Soil and Rock (I). West Conshohocken, PA: ASTM International. DNR. Washington Geologic Information Portal. Washington State Department of Natural Resources. Accessed October 13, 2022. Available online at: https://geologyportal.dnr.wa.gov/. Ecology. 2019. Stormwater Management Manual for Western Washington. Publication No. 19-10-021. Washington State Department of Ecology. July. Data Source: Esri. Yelm High School Soccer Field Conversion and Tennis Courts Reconstruction Yelm, Washington Vicinity Map Figure 1 0 0.5 1 Miles G:\Projects\1444\018\010\011\YelmHSSoccerField\YelmHSSoccerField.aprx 10/15/2022!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! !!! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!! ! ! ! !!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! !!!!!!! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !! ! ! !! ! !!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! !!!!!!!!!!!! ! ! ! ! ! ! ! !! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! !! ! !!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!! ! !!! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!!!!!!!!!!!!!!!!! !!!!!!! ! ! ! !!!!!!!!!!!!!!!!!! ! ! ! ! ! ! ! ! ! ! !!!!!!! ! ! ! ! ! !!!!!!!!! !!!!!!!! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !! ! !!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! !!!!!!!!!!!!!!! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!!!!!!!!!!!!!! ! ! ! ! ! !!!!!!!!!!!!! Bradshaw Rd SE LoisPl SES W M ck e nzi e Ave W e st R d S E OrdwayDr SE Cu llens RdSEVancilRdSEGeorge Rd SE 105th Way SE Co ates R d S E Mo s m a n A v e SW Crystal Springs St NWBurnett Rd SEMudR u n R d S E 3rd St NEMillRdSE93rd Ave SE Killion Rd SE109th Ave SEAnderson L n SE 104th Ave S E 2ndStSECanal R dSE 5 6 th Q uar ter Ma st er R d 89th Ave SE Clark Rd SESE 4thStMountainView RdSERhoton Rd SECull enRd S E Railway Rd S E1st St N Berry Valley Rd S E JoyceCt S E Fox H i l l R d SE 94th Ave SE Longmire St S E 1 66thB riga d e R d Rathbun Rd SEMcnieceDr SE86th Ln SE88th Ave SE 6 0thSig n alBattalionRd510 510 507 507 Yelm ! ! ! ! ! Everett Olympia Seattle Spokane Project Location !Project Location DRAFT Source: Google Maps 2022 Legend 0 120 240 Scale in Feet Note 1. Black and white reproduction of this color original may reduce its effectiveness and lead to incorrect interpretation. Landau Associates | Y:\CAD\1444\018.010\1444018.010.dwg | 10/12/2022 9:50 AM | caduser Yelm High School Soccer Field Conversion and Tennis Courts Reconstruction Yelm, Washington Site Exploration and Location Plan Figure 2 Approximate Test Pit Location and DesignationTP-1 TP-1 TP-2 TP-3 TP-4 93RD AVENUE SOUTHEAST DRAFT 3 Yelm High School Soccer FieldConversion and TennisCourts ReconstructionYelm, WashingtonCOARSE-GRAINED SOIL(More than 50% of coarse fraction retained on No. 4 sieve)(More than 50% of material islarger than No. 200 sieve size)SAND WITH FINES (Appreciable amount of fines) HIGHLY ORGANIC SOIL (Liquid limit greater than 50) SILT AND CLAY RK DB Rock (See Rock Classification) (Liquid limit less than 50) SILT AND CLAY Wood, lumber, wood chips GRAPHIC SYMBOL Construction debris, garbage PAVEMENT ROCK WOOD DEBRIS OTHER MATERIALS TYPICAL DESCRIPTIONS LETTER SYMBOL WD > 30% and < > 15% and < > 5% and < < > _ _ _ _ Primary Constituent: Secondary Constituents: Additional Constituents: Notes: 1. USCS letter symbols correspond to symbols used by the Unified Soil Classification System and ASTM classification methods. Dual letter symbols (e.g., SP-SM for sand or gravel) indicate soil with an estimated 5-15% fines. Multiple letter symbols (e.g., ML/CL) indicate borderline or multiple soil classifications. 2. Soil descriptions are based on the general approach presented in the Standard Practice for Description and Identification of Soils (Visual-Manual Procedure), outlined in ASTM D 2488. Where laboratory index testing has been conducted, soil classifications are based on the Standard Test Method for Classification of Soils for Engineering Purposes, as outlined in ASTM D 2487. 3. Soil description terminology is based on visual estimates (in the absence of laboratory test data) of the percentages of each soil type and is defined as follows: 4. Soil density or consistency descriptions are based on judgement using a combination of sampler penetration blow counts, drilling or excavating conditions, field tests, and laboratory tests, as appropriate. 50% - "GRAVEL," "SAND," "SILT," "CLAY," etc. 50% - "very gravelly," "very sandy," "very silty," etc. 30% - "gravelly," "sandy," "silty," etc. 15% - "with gravel," "with sand," "with silt," etc. 5% - "with trace gravel," "with trace sand," "with trace silt," etc., or not noted. SAMPLER TYPE & METHOD Recovery Depth Interval Sampler Graphic (variable) Code Description a b c d e f g h i 1 2 3 4 5 6 3.25-in OD, 2.42-in ID Split Spoon 2.00-in OD, 1.50-in ID Split Spoon Shelby Tube Grab Sample Single-Tube Core Barrel Double-Tube Core Barrel 2.50-in OD, 2.00-in ID WSDOT 3.00-in OD, 2.37-in ID Mod. Calif. Other - See text if applicable 300-lb Hammer, 30-inch Drop 140-lb Hammer, 30-inch Drop Pushed Sample Vibrocore (Rotosonic/Geoprobe) Other - See text if applicable Piston Extraction 1 Graphic Approximate water level at time after drilling/excavation/well AC or PC CLEAN SAND FINE-GRAINED SOILPT OH CH Well-graded gravel; gravel/sand mixture(s); little or no fines MH OL CL ML SC Field and Lab Test Data Soil Classification System SM SP(Little or no fines)(More than 50% of material is smaller than No. 200 sieve size)Silty gravel; gravel/sand/silt mixture(s) Silty sand; sand/silt mixture(s) Clayey sand; sand/clay mixture(s) Inorganic silt and very fine sand; rock flour; silty or clayey finesand or clayey silt with slight plasticity Inorganic clay of low to medium plasticity; gravelly clay; sandyclay; silty clay; lean clay Organic silt; organic, silty clay of low plasticity Inorganic silt; micaceous or diatomaceous fine sand Inorganic clay of high plasticity; fat clay Organic clay of medium to high plasticity; organic silt MAJOR DIVISIONS Pocket Penetrometer, tsf Torvane, tsf Photoionization Detector VOC screening, ppm Moisture Content, % Dry Density, pcf Material smaller than No. 200 sieve, % Grain Size - See separate figure for data Atterberg Limits - See separate figure for data Other Geotechnical Testing Chemical Analysis PP = 1.0 TV = 0.5 PID = 100 W = 10 D = 120 -200 = 60 GS AL GT CA Groundwater Code SW GC SAMPLE NUMBER & INTERVAL TYPICAL DESCRIPTIONS (2)(3) Asphalt concrete pavement or Portland cement pavement USCS LETTER SYMBOL(1) Approximate water level at time of drilling (ATD) Clayey gravel; gravel/sand/clay mixture(s) GRAPHIC SYMBOL Drilling and Sampling Key Description GM GP GW Poorly graded gravel; gravel/sand mixture(s); little or no fines Well-graded sand; gravelly sand; little or no fines Poorly graded sand; gravelly sand; little or no fines Peat; humus; swamp soil with high organic content CLEAN GRAVELGRAVEL AND GRAVELLY SOIL Sample Depth Interval Portion of Sample Retained for Archive or Analysis Sample Identification Number (Appreciable amount of fines) GRAVEL WITH FINES (Little or no fines) (More than 50% of coarse fraction passed through No. 4 sieve) SAND AND SANDY SOIL Soil Classification System and Key Figure DRAFTPoint located atTest Pit Completed 10/05/22 Total Depth of Test Pit = 8.0 ft. S-1 S-2 d d SP- SM SP GP W = 14 GS 2 inches of grass turf above 4 inches of fine to medium SAND with silt (loose, damp) (TOPSOIL) Dark brown, cobbly, very gravelly, fine to coarse SAND with trace organics (medium dense, damp) (RECESSIONAL OUTWASH) -- occasional small, rounded boulders measuring up to 16 inches Light brown, sandy, fine to coarse GRAVEL with cobbles and boulders (medium dense to dense, damp) -- soil caving; excavation terminated at 8.0 feet 0 2 4 6 8 10 12 Ground Elevation (ft): Excavation Method: CTMLogged By: Rubber-tired Backhoe Not Measured Excavated By:Yelm Community Schools Groundwater Not Encountered GROUNDWATER Elevation (ft)Notes:1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols. TP-1 Sample Number& IntervalSampler TypeTest DataGraphic SymbolUSCS SymbolSAMPLE DATA SOIL PROFILE Depth (ft)Yelm High School Soccer FieldConversion and TennisCourts ReconstructionYelm, Washington Figure1444018.01 10/21/22 \\OLYMPIA1\PROJECTS\1444\018.010\T\1444018.010.GPJ SINGLE TEST PIT LOG4Log of Test Pit TP-1 DRAFTPoint located atTest Pit Completed 10/05/22 Total Depth of Test Pit = 8.0 ft. S-1 S-2 d d SP- SM SP GP W = 6 GS 2 inches of grass turf above 4 inches of fine to medium SAND with silt (loose, damp) (TOPSOIL) Dark brown, cobbly, very gravelly, fine to coarse SAND with trace organics (medium dense, damp) (RECESSIONAL OUTWASH) Light brown, sandy, fine to coarse GRAVEL with cobbles (medium dense to dense, damp) -- soil raveling and caving; excavation terminated at 8.0 feet 0 2 4 6 8 10 12 Ground Elevation (ft): Excavation Method: CTMLogged By: Rubber-tired Backhoe Not Measured Excavated By:Yelm Community Schools Groundwater Not Encountered GROUNDWATER Elevation (ft)Notes:1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols. TP-2 Sample Number& IntervalSampler TypeTest DataGraphic SymbolUSCS SymbolSAMPLE DATA SOIL PROFILE Depth (ft)Yelm High School Soccer FieldConversion and TennisCourts ReconstructionYelm, Washington Figure1444018.01 10/21/22 \\OLYMPIA1\PROJECTS\1444\018.010\T\1444018.010.GPJ SINGLE TEST PIT LOG5Log of Test Pit TP-2 DRAFTPoint located atTest Pit Completed 10/05/22 Total Depth of Test Pit = 9.0 ft. S-1 S-2 d d SP- SM GP- GM SW- SM GP W = 16 GS 2 inches of grass turf above 4 inches of fine to medium SAND with silt (loose, damp) (TOPSOIL) Dark brown, sandy, fine to coarse GRAVEL with silt, cobbles, and trace organics (medium dense, damp) (RECESSIONAL OUTWASH) Light brown, gravelly, fine to coarse SAND with silt (loose to medium dense, damp) -- grades to with cobbles Light brown, cobbly, sandy, fine to coarse GRAVEL (medium dense to dense, damp) 0 2 4 6 8 10 12 Ground Elevation (ft): Excavation Method: CTMLogged By: Rubber-tired Backhoe Not Measured Excavated By:Yelm Community Schools Groundwater Not Encountered GROUNDWATER Elevation (ft)Notes:1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols. TP-3 Sample Number& IntervalSampler TypeTest DataGraphic SymbolUSCS SymbolSAMPLE DATA SOIL PROFILE Depth (ft)Yelm High School Soccer FieldConversion and TennisCourts ReconstructionYelm, Washington Figure1444018.01 10/21/22 \\OLYMPIA1\PROJECTS\1444\018.010\T\1444018.010.GPJ SINGLE TEST PIT LOG6Log of Test Pit TP-3 DRAFTPoint located atTest Pit Completed 10/05/22 Total Depth of Test Pit = 8.0 ft. S-1 S-2 d d SP- SM GP- GM SP GP W = 8 GS 2 inches of grass turf above 4 inches of fine to medium SAND with silt (loose, damp) (TOPSOIL) Dark brown, sandy, fine to coarse GRAVEL with silt and trace organics (medium dense, damp) (RECESSIONAL OUTWASH) Light brown, fine to medium SAND (loose to medium dense, damp) -- grades to very gravelly, with cobbles, and dense Light brown, sandy, fine to coarse GRAVEL (dense, damp) 0 2 4 6 8 10 12 Ground Elevation (ft): Excavation Method: CTMLogged By: Rubber-tired Backhoe Not Measured Excavated By:Yelm Community Schools Groundwater Not Encountered GROUNDWATER Elevation (ft)Notes:1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols. TP-4 Sample Number& IntervalSampler TypeTest DataGraphic SymbolUSCS SymbolSAMPLE DATA SOIL PROFILE Depth (ft)Yelm High School Soccer FieldConversion and TennisCourts ReconstructionYelm, Washington Figure1444018.01 10/21/22 \\OLYMPIA1\PROJECTS\1444\018.010\T\1444018.010.GPJ SINGLE TEST PIT LOG7Log of Test Pit TP-4 DRAFT0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110100 6 Soil Description 60126 1001.5 163 Fine U.S. Sieve Numbers 3/8 140 200 Depth (ft) Natural Moisture (%)Symbol U.S. Sieve Opening in Inches 14 Silt or ClayGravel Unified Soil Classification Grain Size in MillimetersPercent Finer by Weight4 10 303/4 3 20 Sand Hydrometer MediumCoarseCobbles 4 Exploration Number 408 Sample Number Coarse 1/2 50 Fine SP GP SW-SM SP S-1 S-2 S-1 S-1 Very gravelly, fine to coarse SAND Sandy, fine to coarse GRAVEL Gravelly, well-graded SAND with silt Fine to medium SAND 14 6 16 8 1.5 3.0 3.0 2.0 TP-1 TP-2 TP-3 TP-4 Yelm High School Soccer FieldConversion and TennisCourts ReconstructionYelm, Washington Figure 1444018.01 10/12/22 \\OLYMPIA1\PROJECTS\1444\018.010\T\1444018.010.GPJ GRAIN SIZE FIGURE 8Grain Size Distribution