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SWPPP-4166
Page | 1 Construction Stormwater General Permit (CSWGP) Stormwater Pollution Prevention Plan (SWPPP) for Elliott Farms Prepared for: Department of Ecology Northwest Regional Office Permittee / Owner Developer Operator / Contractor TriPoint Homes TriPoint Homes Johansen Construction Company 14207 Maple Valley Rd. Renton, WA 98058 Update as necessary. Certified Erosion and Sediment Control Lead (CESCL) Name Organization Contact Phone Number Tom Shugrue WaterTech NW 206-972-3720 SWPPP Prepared By Name Organization Contact Phone Number Tim Tobin Barghausen Consulting Engineers, Inc. 425-251-6222 SWPPP Preparation Date Month / Day / Year Project Construction Dates Activity / Phase Start Date End Date Site and Home Construction MM / DD / YYYY MM / DD / YYYY DEVELOPMENT ENGINEERING msippo 05/10/2021 Page | 2 Table of Contents Project Information (1.0) ............................................................................................................. 5 Existing Conditions (1.1) ......................................................................................................... 6 Proposed Construction Activities (1.2) .................................................................................... 7 Construction Stormwater Best Management Practices (BMPs) (2.0) .......................................... 9 The 12 Elements (2.1) ............................................................................................................ 9 Element 1: Preserve Vegetation / Mark Clearing Limits (2.1.1) ........................................... 9 Element 2: Establish Construction Access (2.1.2) ..............................................................10 Element 3: Control Flow Rates (2.1.3) ...............................................................................11 Element 4: Install Sediment Controls (2.1.4) ......................................................................12 Element 5: Stabilize Soils (2.1.5) .......................................................................................14 Element 6: Protect Slopes (2.1.6) ......................................................................................16 Element 7: Protect Drain Inlets (2.1.7) ...............................................................................17 Element 8: Stabilize Channels and Outlets (2.1.8) .............................................................18 Element 9: Control Pollutants (2.1.9) ..................................................................................19 Element 10: Control Dewatering (2.1.10) ...........................................................................26 Element 11: Maintain BMPs (2.1.11) ..................................................................................27 Element 12: Manage the Project (2.1.12) ...........................................................................28 2.1.13 Element 13: Protect Low Impact Development (LID) BMPs .................................31 Pollution Prevention Team (3.0) ................................................................................................32 Monitoring and Sampling Requirements (4.0) ...........................................................................33 Site Inspection (4.1) ...............................................................................................................33 Stormwater Quality Sampling (4.2) ........................................................................................33 Turbidity Sampling (4.2.1) ..................................................................................................33 pH Sampling (4.2.2) ...........................................................................................................35 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies (5.0) ........................36 303(d) Listed Waterbodies (5.1) ............................................................................................36 TMDL Waterbodies (5.2) .......................................................................................................36 Reporting and Record Keeping (6.0) .........................................................................................37 Record Keeping (6.1) ............................................................................................................37 Site Log Book (6.1.1) .........................................................................................................37 Records Retention (6.1.2) ..................................................................................................37 Updating the SWPPP (6.1.3)..............................................................................................37 Reporting (6.2) ......................................................................................................................38 Discharge Monitoring Reports (6.2.1) .................................................................................38 Notification of Noncompliance (6.2.2) .................................................................................38 Page | 3 List of Tables Table 1 – Summary of Site Pollutant Constituents .................................................................. Table 2 – Pollutants ................................................................................................................... Table 3 – pH-Modifying Sources ............................................................................................... Table 4 – Dewatering BMPs ....................................................................................................... Table 5 – Management ............................................................................................................... Table 6 – BMP Implementation Schedule ................................................................................. Table 7 – Team Information ....................................................................................................... Table 8 – Turbidity Sampling Method ....................................................................................... Table 9 – pH Sampling Method ................................................................................................. List of Appendices Apendix/Glossary A. Site Map B. BMP Detail C. Correspondence D. Site Ispection Form E. Construction Stormwater General Permit (CSWGP) F. 303(d) List Waterbodies / TMDL Waterbodies Information G. Contaminated Site Information H. Engineering Calculations 7 19 24 26 28 29 32 33 35 Page | 4 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 Page | 5 Project Information (1.0) This Stormwater Pollution Prevention Plan (SWPPP) has been prepared per the requirements of the Washington State NPDES Construction Stormwater General Permit Conditions of Approval for the Elliot Farms project in the City of Renton, Washington. The proposed Plat of Elliott Farms is an attached single-family residential project consisting of 45 lots, zoned R-14. The tax parcel number is 2223059004 and is 6.07 acres in size. The site is located on the south side and adjacent to Maple Valley Hwy (WA-169) at the eastern terminus of 140th Way SE (Private Road) in the Molasses Creek Condominiums, in a portion of Section 22, Township 23 North, Range 5 East, W.M., in the City of Renton. The site is rectangular in shape with 691.70’ of frontage along Maple Valley Hwy (WA-169). Condominium units, known as Molasses Creek Phase 1, is located on the west side of the project that provides access into the project. A single family residential development, known as Pioneer Place, is located to the east and a single family residence is located south. A wetland exists at the southwest corner of the site with a 50’ buffer. This site is currently undeveloped, but contains remnants from an existing farm, including partially buried building foundations and concrete slabs. Existing on-site utilities were constructed along the northern portion of the site for this development. On-site soils are mapped as Newberg (till soils). The proposed on-site road will utilize vertical curb and gutter with depressed curb and sidewalk at driveway connections. The road will connect to the existing 140th Way S.E that was stubbed to the property by Molasses Creek. The private alley will be extended into the site to provide private access and circulation. An emergency access will be provided to WA-169. Frontage improvements along WA-169 are required, including new asphalt, new curb and gutter, sidewalk, and planter strip. The project is proposing to install a piped conveyance system along the frontage to convey the runoff from WA-169 and a portion of the site to the existing ditch along Molasses creek frontage. The on-site topography is generally flat. The southwest corner of the project gently slopes toward the wetland. Please refer to Section 4.0 for a discussion on maintaining wetland hydrology. The remaining portion of the site drains into the roadside ditch along WA-169. There is an existing drainage ditch along the east side of the project that conveys off-site upstream flows from the southeast. The elevations on the site range from 107 to 87. The project will be mass graded to provide flat home sites for the future homes. It is expected that that site will import soils to provide necessary cover over existing and future utilities. The drainage system for this project is required to meet the requirements of the 2009 King County Surface Water Design Manual (KCSWDM), and the 2010 City of Renton Amendments to the KCSWDM. Flow control is exempt for this project as the projects drainage flows to the Cedar River which is listed as a receiving water in core requirement no. 3. The water quality facility (wetpond) that was built with previous development was sized to accommodate the project. Construction activities will include demolition, clearing & grading, roadwork, stormwater conveyance installation, utilities installation, foundation excavation, home construction, driveway & patio construction, and landscaping. Construction is scheduled to begin on June 1, 2021 and estimated to be completed on December 31, 2022. The purpose of this SWPPP is to describe the proposed construction activities and all temporary and permanent erosion and sediment control (TESC) measures, pollution prevention measures, inspection/monitoring activities, and Page | 6 recordkeeping that will be implemented during the proposed construction project. The objectives of the SWPPP are to: 1. Implement Best Management Practices (BMPs) to prevent erosion and sediment, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. Prevent violations of surface water quality, ground water quality, or sediment management standards. 3. During the construction phase prevent adverse water quality impacts including, impacts of beneficial uses of the receiving water by controlling peak flow rates and volumes of stormwater runoff at the Permittee's outfalls and downstream of the outfalls. This SWPPP was prepared using the Ecology SWPPP Template downloaded from the Ecology website on March 15, 2021. The Template has been revised to incorporate all items in the General NPDES Permit as well as provide more project specific BMPs that will be utilized onsite. This SWPPP was prepared based on the requirements set forth in the Construction Stormwater General Permit, Stormwater Management Manual for Western Washington (SWMMWW 2012). The site project information for the site is summarized below. Project/Site Name: Elliott Farms Street/Location: 14207 Maple Valley Rd City:Renton State:WA Zip Code:98058 Subdivision: Elliott Farms Receiving waterbody: Cedar River Existing Conditions (1.1) As previously mentioned, the total site area is approximately 6.07 acres in size. The site is currently undeveloped, but contains remnants from an existing farm, including partially buried building foundations and concrete slabs. Existing on-site utilities were constructed along the northern portion of the site for this development. A wetland exists at the southwest corner of the site with a 50’ buffer. The on-site topography is generally flat. The southwest corner of the project gently slopes toward the wetland. Please refer to Section 4.0 for a discussion on maintaining wetland hydrology. The remaining portion of the site drains into the roadside ditch along WA-169. There is an existing drainage ditch along the east side of the project that conveys off-site upstream flows from the southeast. The elevations on the site range from 107 to 87. The project will be mass graded to provide flat home sites for the future homes. It is expected that that site will import soils to provide necessary cover over existing and future utilities Page | 7 Total acreage: 6.07 Disturbed acreage: 5.06 Existing structures: Concrete foundations from previous structures Landscape topography: Lightly treed, brush and grass. Drainage patterns: Most of the site drains North to the SR169 roadside ditch with a portion draining south to the Cat. 2 Wetland Existing Vegetation: Mostly weeds, grass, and brush. Southwest corner of site contains mixed variety of trees. Critical Areas (wetlands, streams, high erosion risk, steep or difficult to stabilize slopes): Category 2 Wetland, List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the receiving waterbody: None Table 1 includes a list of suspected and/or known contaminants associated with the construction activity. Table 1 – Summary of Site Pollutant Constituents Constituent (Pollutant) Location Depth Concentration N/A N/A N/A N/A Proposed Construction Activities (1.2) The site will be cleared according to the T.E.S.C. and Grading Plans. The permanent stormwater conveyance system will be built according to the Road and Drainage Plans. The proposed development includes site development and eventual home construction of 45 residential lots for the construction of attached two- and three-unit buildings pathways and roadways. A system of pipes and catch basins will be installed to convey stormwater runoff from the developed site and any onsite contributing basin areas to the existing stormwater facility located west of 140th Way SE. The existing facility was designed to provide the required water quality and was sized to accommodate this project. Page | 8 The site will be constructed in two phases, the Site Development Phase and the Vertical Construction Phase. The site development construction phase includes the following activities: Clearing & Grubbing, Demolition, Sediment Pond and Sediment Trap, Mass Grading/Site Grading, Infrastructure (utilities, curb and gutter, sidewalks, drives, etc.), and paving operations. Description of site drainage including flow from and onto adjacent properties. Must be consistent with Site Map in Appendix A: In the developed condition stormwater runoff will be routed to the offsite existing stormwater facility. Through the project constructed conveyance pipes that connect to the offsite stormwater pipe system within Molasses Creek Apartments and the roadside ditch along WA-169. A portion of the developed site will be directed to the existing wetland to the south to maintain wetland hydrology. In the developed condition the site will be mostly developed. All nonimpervious developed surfaces will be vegetated with a variety of local shrubs and grass. Contaminated Site Information: There are no activities that will result in the contamination of soil and or groundwater planned for the site during clearing, grading, and/or the construction of the attached two- and three-unit residences. Page | 9 Construction Stormwater Best Management Practices (BMPs) (2.0) The following sections describe BMPs that will be utilized during the construction of the project. Alternate BMPs for the 12 BMP Elements may be implemented on a need by need basis, should the 12 Elements below be deemed ineffective or inappropriate during the construction to satisfy the requirements set forth in the General NPDES Permit. To avoid potential erosion and sediment control issues that may cause violation(s) of the NPDES Construction Stormwater permit, the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more alternate BMPs after the first sign that existing BMPs are ineffective or failing. The SWPPP is a living document reflecting current conditions and changes throughout the life of the project. These changes may be informal (i.e. hand-written notes and deletions). Update the SWPPP when the CESCL has noted a deficiency in BMPs or deviation from original design. The 12 Elements (2.1) Element 1: Preserve Vegetation / Mark Clearing Limits (2.1.1) 5.06 acres of the site are to be developed and mass graded to balance cut and fills. To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. Trees that are to be preserved, as well as all sensitive areas and their buffers, shall be clearly delineated, both in the field and on the plans. In general, natural vegetation and native top shall be retained in an undisturbed state to the maximum extent possible. The BMP relevant to marking the clearing limits that will be applied for this project include the following: List and describe BMPs: High Visibility Fence (BMP C103) Install colored orange fence to protect areas that are not to be disturbed, and mark trees to be preserved. Silt Fence (BMP C233) Silt fencing shall be used to control sediment flow offsite throughout the construction process. Installation Schedules: All BMPs to preserve vegetation and mark clearing limits are to be installed prior to clearing and grading Inspection and Maintenance plan: All fencing is to be inspected at the end of each day's work and repaired if found to noncompliant with BMP specifications Responsible Staff: Certified Erosion and Sediment Control Lead Page | 10 Element 2: Establish Construction Access (2.1.2) Construction access or activities occurring on unpaved areas shall be minimized, yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads. Street sweeping and street cleaning shall be employed where necessary to prevent sediment from entering state waters. All wash wastewater shall be controlled onsite. The specific BMPs related to establishing construction access hat will be used on this project are as follows: List and describe BMPs: Stabilized Construction Entrance (BMP C105) One quarry spall construction entrance will be placed at the dead end of 124th PL SE, near the proposed entrance to the site. This stabilized construction entrance will be used to minimize the amount of sediment transported off site onto the existing roadway by construction traffic. Construction Road/Parking Area Stabilization (BMP C107) Proposed roads shall be stabilized immediately after grading to reduce erosion by construction traffic or surface water runoff. During vertical construction, apply quarry spall base on drive approaches for buildings lot/pad access or in other high traffic areas such as material equipment storage and concrete washout areas. Concrete Washout Area (BMP C154) Conduct washout off-site, or perform on-site concrete washout in a designated area. This is done to prevent pollutants from entering surface or ground water If sediment is tracked off site, clean the affected roadway thoroughly at the end of each day or more frequently, as necessary. Remove sediment from roads by shoveling, sweeping, or pickup and transport of the sediment to a controlled sediment disposal area. Conduct street washing only after sediment removal in accordance with special condition S9.D.2.d. Control street wash wastewater by pumping back on site or otherwise preventing it from discharging off site into catch basins, stormwater conveyance systems, creek, or rivers that connect to waters of the State. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Page | 11 Element 3: Control Flow Rates (2.1.3) 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: Temporary Sediment Trap (BMP C240) The contractor shall size and constructed temporary sediment pond located in Tract D near Lot 19, or other approved locations. A temporary outfall shall discharge runoff to the existing drainage ditch located along the South side of SR-169 and used during construction to mitigate onside runoff. Temporary Sediment Pond (BMP C241) The contractor shall size and constructed temporary sediment pond located in the western portion of Tract A, or other approved locations. A temporary outfall shall discharge runoff to the existing drainage ditch located along the South side of SR-169 and used during construction to mitigate onside runoff. The project site is located west of the Cascade Mountain Crest. As a result, the project must comply with the Minimum Requirement 7 (Ecology 2012). Minimum Requirement 7 states that projects must provide flow control to reduce the impacts of stormwater runoff from impervious surfaces and land cover conversions. Essentially, discharge rates of stormwater from the site will be controlled where increases in impervious area or soil compaction during construction could lead to downstream erosion, or where necessary to meet local agency stormwater discharge requirements (e.g. discharge to combined sewer systems). Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Page | 12 Element 4: Install Sediment Controls (2.1.4) All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site. The specific BMPs to be used for controlling sediment on this project are as follows: List and describe BMPs: Silt Fence (BMP C233) During site development phase, silt fence will be used along the downhill perimeter of the project to prevent sediment from leaving the site. During the homebuilding phase, sediment control will not be necessary on all lots prior to disturbance, as many are flat with well established grass cover. Temporary stabilized lots with slope, or less well established grass cover will be inspected during wet weather conditions and, if required, silt fence may be used as a sediment control. Before removing vegetation on the lots, silt fence will be installed as a sediment control behind curb. Storm Drain Inlet Protection (BMP C220) Catch basins and storm drain inlets within the project boundary and downstream will have an approved from of inlet protection installed. This will prevent coarse sediment from entering the drainage system prior to permanent stabilization of the disturbed draining area. In additions, sediment will be removed from paved areas in and adjacent to construction work areas manually or using a mechanical sweepers, as needed to minimize tracking of sediments on vehicle tires away from the site and to minimize the transmission of sediments from adjacent streets in runoff The following BMPs will be implemented as end-of-pipe sediment controls as required to meet permitted turbidity limits in the sit discharge(s). Prior to the implementation of these methods, sediment sources and erosion control and soil stabilization BMP efforts will be maximized to reduce the need for end-of-pipe sediment controls. Temporary Sediment Trap (BMP C240) Temporary Sediment Pond (BMP C241) Construction Stormwater Filtration (BMP C251) Construction Stormwater Chemical Treatment (BMP C250) (Implemented only with prior written approval from Ecology.) Page | 13 Implement BMP C250/251 above end-of-pipe measures only if sediment sources and erosion control and soil stabilization BMP efforts are not sufficient to reduce sedimentation Installation Schedules: Installation schedule to be determined by the General Contractor. Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Page | 14 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. The specific BMPs for soil stabilization that shall be used in this project are as follows: 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: June 1, 2021 End date: December 31, 2022 Will you construct during the wet season? Yes No List and describe BMPs: Temporary and Permanent Seeding (BMP C120) Following final or fine grading activity in the rear and side yards, permanent seeding shall be placed on exposed soil to provide permanent erosion protection. Mulching (BMP C121) During the site development phase, mulching will be used for areas that will be unworked for more than 2 days. Temporary seeding will be applied to areas that will be unworked for more than 7 days. During the home building phase, the construction area will be significantly stabilized through well established grass cover. Proposed driveways will receive base course materials as described under Element #2 above. Areas cleared for building foundations or utility and irrigation placement will be temporarily stabilized by one of the following methods which are based on the period exposed soils are left unworked: o If exposed soils are left unworked for more than 7 days during the dry season and 2 days during the wet season but less than 30 days, mulching shall be applied. o If exposed soils are left unworked for more than 30 days, temporary or permanent seeding shall be applied. Page | 15 Nets and Blankets (BMP C122) Once final or fine grading activity has been completed, install Jute Matting on slopes prior to planting. Sodding (BMP C124) Following final or fine grading activity in the front yard, sod shall be placed on exposed soil to provide permanent and immediate erosion protection. Plastic Covering (BMP C123) Topsoiling (BMP C125) Utilize stockpile management during all phases of construction per BMP. Cover stockpiles with plastic covering to prevent erosion during rain events. Wattles (BMP C235) Install wattles downslope of newly landscaped areas to control sediment runoff until stabilization. Cement or Calcium Chloride may be used for soil stabilization and dewatering. See section 4.2.2 for pH Sampling Requirements. The project site is located west of the Cascade Mountain Crest. As such, no soils shall remain exposed and unworked for more than 7 days during the dry season (May 1 to September 30) and 2 days during the wet season (October 1 to April 30). Regardless of the time of year, all soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on weather forecasts. Cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. 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. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Page | 16 Element 6: Protect Slopes (2.1.6) All cut and fill slopes will be designed, constructed, and protected in a manner that minimizes erosion. The following specific BMPs will be used to protect slopes for this project: Will steep slopes be present at the site during construction? Yes No List and describe BMPs: Temporary and Permanent Seeding (BMP C120) The site is moderately sloped (less than 15%). Sloping areas will be treated as described under Element 5 above. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Page | 17 Element 7: Protect Drain Inlets (2.1.7) Drain inlets will be protected using the following BMP methods: List and describe BMPs: Storm Drain Inlet Protection (BMP C220) Prior to construction, storm drain inlet protection will be utilized on all catch basins in the roadway along the frontage of any areas receiving stormwater from construction activities within the permitted area. Install inlet protection once permanent storm drain inlets on site are constructed. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Page | 18 Element 8: Stabilize Channels and Outlets (2.1.8) Where site runoff is to be conveyed in channels, or discharged to a stream or some other natural drainage point, efforts will be made to prevent downstream erosion. The specific BMPs for channel and outlet stabilization that shall be used on this project include: Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches, will be installed at the outlets of all conveyance systems. List and describe BMPs: Interceptor Dike and Swale (BMP C200) During the site development phase, interceptor dikes and swales shall be constructed down slope and on site of the construction site to convey stormwater to an erosion control facility. Check Dams (BMP C207) Check dams shall be used to reduce the velocity and energy of concentrated flow in swales or ditches. Outlet Protection (BMP C209) Outlet protection will be constructed at the outlet location of the storm drainage piping to prevent erosion. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Page | 19 Element 9: Control Pollutants (2.1.9) All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well organized, and free of debris. If required, BMPs to be implemented to control specific sources of pollutants are discussed below. The following pollutants are anticipated to be present on-site: Table 2 – Pollutants Pollutant (and source, if applicable) Installation of sediment and erosion controls Installation of stabilized exits Vehicle tracking Clearing and grubbing operations Grading operations Exposed soils and slopes Import/export operations Utility excavation operations Landscapeing operations Topsoil stripping and stockpiling Fine grading of home sites Vertical Construction Concrete Housekeeping BMPs The following sections describe the controls, including storage practices to minimize exposure of the materials to stormwater as well as spill prevention and response practices. All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Vehicles, construction equipment, and/or petroleum product storage/dispensing: All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. Secondary containment such as drip pans will be placed under any leaking vehicles or equipment. All petroleum product storage containers will be placed in secondary containment (see spill prevention and control below). On-site fueling tanks and petroleum product storage containers shall include secondary containment. Page | 20 Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment or when vehicle/equipment leaks are observed. In order to perform emergency repairs on site, temporary plastic will be placed beneath and, if raining, over the vehicle. Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Chemical storage: Any chemicals stored in the construction areas will conform to the appropriate source control BMPs listed in Volume IV of the Ecology stormwater manual. In Western WA, all chemicals shall have cover, containment, and protection provided on site, per BMP C153 for Material Delivery, Storage and Containment in SWMMWW 2012. Application of agricultural chemicals, including fertilizers and pesticides, shall be conducted in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Manufacturers’ recommendations for application procedures and rates shall be followed. Concrete and grout: Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures (BMP C151) and Sawcutting and Surfacing Pollution Prevention (BMP C152). Sanitary wastewater: Proper sanitary and septic waste management are waste management and material pollution controls that prevent the discharge of pollutants to stormwater from sanitary and septic waste by providing convenient, well-maintained facilities, and arranging for regular service and disposal. Implement as follows: o Facilities should be located away from drainage facilities, watercourses, and from traffic circulation. o Provide a sufficient quantity of facilities to accommodate the workforce. o Temporary sanitary facilities must be equipped with containment to prevent discharge of pollutants to the stormwater drainage system of the receiving water. o When subjected to high winds or risk of high winds, temporary sanitary facilities should be secured to prevent overturning. o Sanitary facilities should be located in a convenient location. o Sanitary or septic wastes should be treated or disposed of in accordance with state and local requirements. Page | 21 o Sanitary facilities should be maintained in good working order by a licensed service. Solid and Liquid Waste: Solid and liquid waste generated during construction such as construction materials, contaminated materials, and waste materials from maintenance activities will be prevented from entering the waters of the State. Solid and liquid waste shall be handled in accordance with BMPs for Storage of Liquid, Food Waste, or Dangerous Waste Containers and BMPs for Loading and Unloading Areas for Liquid or Solid Materials. o Solid waste will be stored in secure, clearly marked containers. o Promptly contain and clean up solid and liquid pollutant leaks and spills including oils, solvents, fuels, and dust from manufacturing operations on any exposed soil, vegetation, or paved area. o Sweep paved material handling and storage areas regularly as needed, for the collection and disposal of dust and debris that could contaminate stormwater. Do not hose down pollutants from any area to the ground, storm drain, conveyance ditch, or receiving water unless necessary for dust control purposes to meet air quality regulations. Installation Schedules: The described BMPs will be implemented while all pollution generating materials are onsite. Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site? Yes No Spill Prevention and Control BMPs Prevent or reduce the discharge of pollutants to drainage systems or watercourses from leaks and spills by reducing the chance for spills, stopping the source of spills, containing and cleaning up spills, properly disposing of spill materials, and training employees. This best management practice covers only spill prevention and control. However, Materials Delivery and Storage (BMP C153), also contains useful information, particularly on spill prevention. To the extent that the work can be accomplished safely, spills of oil, petroleum products, and substances listed under 40 CFR parts 110,117, and 302, and sanitary and septic wastes should be contained and cleaned up immediately. Store hazardous materials and wastes in covered containers and protect from vandalism. Page | 22 Place a stockpile of spill cleanup materials where it will be readily accessible. Train employees in spill prevention and cleanup. Designate responsible individuals to oversee and enforce control measures. Spills should be covered and protected from stormwater runon during rainfall to the extent that it doesn’t compromise cleanup activities. Do not bury or wash spills with water. Store and dispose of used clean up materials, contaminated materials, and recovered spill material that is no longer suitable for the intended purpose in conformance with the provisions in applicable BMPs. Do not allow water used for cleaning and decontamination to enter storm drains or watercourses. Collect and dispose of contaminated water in accordance WSDOE regulations. Contain water overflow or minor water spillage and do not allow it to discharge into drainage facilities or watercourses. Place proper storage, cleanup, and spill reporting instructions for hazardous materials stored or used on the project site in an open, conspicuous, and accessible location. Keep waste storage areas clean, well organized, and equipped with ample clean supplies as appropriate for the materials being stored. Perimeter controls, containment structures, covers, and liners should be repaired or replaced as needed to maintain proper function. Cleanup: Clean up leaks and spills immediately. Use a rag for small spills on paved surfaces, a damp mop for general cleanup, and absorbent material for larger spills. If the spilled material is hazardous, then the used cleanup materials are also hazardous and must be sent to either a certified laundry (rags) or disposed of as hazardous waste. Never hose down or bury dry material spills. Clean up as much of the material as possible and dispose of properly. The spill kit should include, at a minimum: o 1-Water Resistant Nylon Bag o 3-Oil Absorbent Socks 3”x 4’ o 2-Oil Absorbent Socks 3”x 10’ o 12-Oil Absorbent Pads 17”x19” o 1-Pair Splash Resistant Goggles o 3-Pair Nitrile Gloves o 10-Disposable Bags with Ties o Instructions Spill kits will be located in areas with a high potential for spills and deployed in a manner that allows rapid access and use by contractors. Some heavy equipment may have on- board spill kits for small spills. Spill control kits will be inspected and inventoried each construction season to confirm all required items are present. Spill control kits will be inventoried after each emergency event and restocked as needed. Page | 23 Minor Spills: Minor spills typically involve small quantities of oil, gasoline, paint, etc. which can be controlled at the discovery of the spill. Contain the spread of the spill. Use absorbent materials on small spills rather than hosing down or burying the spill. Notify the project foreman immediately Recover spilled materials. Clean the contaminated area and properly dispose of contaminated materials. If the spill occurs on paved or impermeable surfaces, clean up using "dry" methods (absorbent materials, cat litter and/or rags). Contain the spill by encircling with absorbent materials and do not let the spill spread widely. If the spill occurs in dirt areas, immediately contain the spill by constructing an earthen dike. Dig up and properly dispose of contaminated soil. If the spill occurs during rain, cover spill with tarps or other material to prevent contaminating runoff. Semi-Significant Spills: Semi-significant spills still can be controlled by the first responder along with the aid of other personnel such as laborers and the foreman, etc. This response may require the cessation of all other activities. Spills should be cleaned up immediately. Significant/Hazardous Spills For significant or hazardous spills that cannot be controlled by personnel in the immediate vicinity, the following steps should be taken: o Notify the local emergency response by dialing 911. In addition to 911, the contractor will notify the proper City or County officials. All emergency phone numbers will be posted at the construction site. o Contact your Supervisor and the Divisional Environmental Manager. For spills of federal reportable quantities, (examples are listed below) in conformance with the requirements in 40 CFR parts 110,119, and 302, the Division Environmental Manager (DEM) will notify the National Response Center at (800) 424-8802. The DEM will notify the Department of Ecology and any other applicable agencies. The services of a spills contractor or a Haz-Mat team should be obtained immediately. Construction personnel should not attempt to clean up until the appropriate and qualified staffs have arrived at the job site. Notification should first be made by telephone and followed up with a written report. Other agencies which may need to be consulted include, but are not limited to, the Public Works Department, the Coast Guard, the Highway Patrol, the City/County Police Department and Department of Ecology. Page | 24 Federal regulations require that any significant oil spill into a water body or onto an adjoining shoreline be reported to the National Response Center (NRC) at 800-424-8802 (24 hours) Installation Schedules: The described BMPs will be implemented while all pollution generating materials are onsite. Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Will wheel wash or tire bath system BMPs be used during construction? Yes No Wheel Wash (BMP C106) Discharge wheel wash or tire bath wastewater to a separate on-site treatment system that prevents discharge to surface water, such as closed-loop recirculation or upland land application, or to the sanitary sewer with local sewer district approval. Installation Schedules: The described BMPs will be implemented while all pollution generating materials are onsite. Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Will pH-modifying sources be present on-site? Yes No If yes, check the source(s). Table 3 – pH-Modifying Sources None x Bulk cement Cement kiln dust Fly ash x Other cementitious materials x New concrete washing or curing waters x Waste streams generated from concrete grinding and sawing Exposed aggregate processes Dewatering concrete vaults x Concrete pumping and mixer washout waters Page | 25 Recycled concrete Other (i.e. calcium lignosulfate) [please describe] List and describe BMPs: pH Control for High pH Water (BMP C253) High pH Neutralization using CO2 (BMP C252) (Implemented only after notifying the local Jurisdiction.) Sawcutting and Surfacing Pollution Prevention Installation Schedules: The described BMPs will be implemented while all pollution generating materials are onsite. Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Adjust pH of stormwater if outside the range of 6.5 to 8.5 su. Obtain written approval from Ecology before using chemical treatment with the exception of CO2 or dry ice to modify pH. 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. Page | 26 Element 10: Control Dewatering (2.1.10) There will be no dewatering as part of this construction project. 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: None Installation Schedules: None Inspection and Maintenance plan: None Responsible Staff: None Page | 27 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. Page | 28 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) Page | 29 Optional: Fill out Table 6 by listing the BMP associated with specific construction activities. Identify the phase of the project (if applicable). To increase awareness of seasonal requirements, indicate if the activity falls within the wet or dry season. Table 6 – BMP Implementation Schedule Phase of Construction Project Stormwater BMPs Date Wet/Dry Season [Insert construction activity] [Insert BMP] [MM/DD/YYYY] [Insert Season] Page | 30 Phase of Construction Project Stormwater BMPs Date Wet/Dry Season [Insert construction activity] [Insert BMP] [MM/DD/YYYY] [Insert Season] Page | 31 2.1.13 Element 13: Protect Low Impact Development (LID) BMPs N/A Page | 32 Pollution Prevention Team (3.0) Table 7 – Team Information Title Name(s) Phone Number Certified Erosion and Sediment Control Lead (CESCL) Tom Shugrue WaterTech NW 206-972-3720 Resident Engineer Barry Talkington 425-251-6222 Emergency Ecology Contact Emergency Permittee/ Owner Contact Non-Emergency Owner Contact Monitoring Personnel Ecology Regional Office 3190 160th Ave SE, Bellevue, WA (425) 649-7000 Page | 33 Monitoring and Sampling Requirements (4.0) Monitoring includes visual inspection, sampling for water quality parameters of concern, and documentation of the inspection and sampling findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: A record of the implementation of the SWPPP and other permit requirements Site inspections Stormwater sampling data Create your own Site Inspection Form or use the Construction Stormwater Site Inspection Form found on Ecology’s website. https://www.ecology.wa.gov/Regulations-Permits/Permits- certifications/Stormwater-general-permits/Construction-stormwater-permit File a 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. The discharge point(s) are indicated on the Site Map (see Appendix A) and in accordance with the applicable requirements of the CSWGP. Stormwater Quality Sampling (4.2) Turbidity Sampling (4.2.1) Requirements include calibrated turbidity meter or transparency tube to sample site discharges for compliance with the CSWGP. Sampling will be conducted at all discharge points at least once per calendar week. Method for sampling turbidity: Table 8 – Turbidity Sampling Method Turbidity Meter/Turbidimeter (required for disturbances 5 acres or greater in size) 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. Page | 34 If the discharge’s turbidity is 26 to 249 NTU or the transparency is less than 33 cm but equal to or greater than 6 cm, the following steps will be conducted: 1. Review the SWPPP for compliance with Special Condition S9. Make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. 3. Document BMP implementation and maintenance in the site log book. If the turbidity exceeds 250 NTU or the transparency is 6 cm or less at any time, the following steps will be conducted: 1. Telephone or submit an electronic report to the applicable Ecology Region’s Environmental Report Tracking System (ERTS) within 24 hours. https://www.ecology.wa.gov/About-us/Get-involved/Report-an-environmental-issue Central Region (Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, Yakima): (509) 575-2490 Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400 Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish, Whatcom): (425) 649-7000 Southwest Region (Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, Wahkiakum,): (360) 407-6300 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period 3. Document BMP implementation and maintenance in the site log book. 4. Continue to sample discharges daily until one of the following is true: Turbidity is 25 NTU (or lower). Transparency is 33 cm (or greater). Compliance with the water quality limit for turbidity is achieved. o 1 - 5 NTU over background turbidity, if background is less than 50 NTU o 1% - 10% over background turbidity, if background is 50 NTU or greater The discharge stops or is eliminated. Page | 35 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 – pH Sampling Method x pH meter pH test kit Wide range pH indicator paper 9 Page | 36 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies (5.0) 303(d) Listed Waterbodies (5.1) The 303(d) status is listed on the Water Quality Atlas: https://ecology.wa.gov/Water- Shorelines/Water-quality/Water-improvement/Assessment-of-state-waters-303d Circle the applicable answer, if necessary: Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH? Yes No List the impairment(s): TMDL Waterbodies (5.2) Waste Load Allocation for CWSGP discharges: [Insert text here] List and describe BMPs: Discharges to TMDL receiving waterbodies will meet in-stream water quality criteria at the point of discharge. The Construction Stormwater General Permit Proposed New Discharge to an Impaired Water Body form is included in Appendix F. Page | 37 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. Page | 38 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. Central Region at (509) 575-2490 for Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, or Yakima County Eastern Region at (509) 329-3400 for Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, or Whitman County Northwest Region at (425) 649-7000 for Island, King, Kitsap, San Juan, Skagit, Snohomish, or Whatcom County Southwest Region at (360) 407-6300 for Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, or Wahkiakum Page | 39 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. Page | 40 Appendix/Glossary A. Site Map The site map must meet the requirements of Special Condition S9.E of the CSWGP B. BMP Detail Insert BMPs specification sheets here. Download BMPs from the Ecology Construction Stormwater website at: https://www.ecology.wa.gov/Regulations-Permits/Guidance-technical- assistance/Stormwater-permittee-guidance-resources/Stormwater-manuals C. Correspondence Ecology EPA Local Government D. Site Inspection Form Create your own or download Ecology’s template: https://www.ecology.wa.gov/Regulations-Permits/Permits-certifications/Stormwater- general-permits/Construction-stormwater-permit E. Construction Stormwater General Permit (CSWGP) Download CSWGP: https://www.ecology.wa.gov/Regulations-Permits/Permits- certifications/Stormwater-general-permits/Construction-stormwater-permit F. 303(d) List Waterbodies / TMDL Waterbodies Information Proposed New Discharge to an Impaired Water Body form SWPPP Addendum addressing impairment G. Contaminated Site Information Administrative Order Sanitary Discharge Permit Soil Management Plan Soil and Groundwater Reports Maps and Figures Depicting Contamination H. Engineering Calculations Exhibit A Site Map IN COMPLIANCE WITH CITY OF RENTON STANDARDSTED-40-4166TRIPOINTE(425) 455-290015900 SE EASTGATE WAY. SUITE 300BELLEVUE, WA 98008ELLIOTT FARMSLUA: 15-000242C: 20-005641ELLIOTT FARMSPR: 15-003117ELLIOTT FARMS ” SCALE: 1"=50' · R-416606 04/21/21 IN COMPLIANCE WITH CITY OF RENTON STANDARDSTED-40-4166TRIPOINTE(425) 455-290015900 SE EASTGATE WAY. SUITE 300BELLEVUE, WA 98008ELLIOTT FARMSLUA: 15-000242C: 20-005641ELLIOTT FARMSPR: 15-003117ELLIOTT FARMS ” ” R-416607 04/21/21 IN COMPLIANCE WITH CITY OF RENTON STANDARDSTED-40-4166TRIPOINTE(425) 455-290015900 SE EASTGATE WAY. SUITE 300BELLEVUE, WA 98008ELLIOTT FARMSLUA: 15-000242C: 20-005641ELLIOTT FARMSPR: 15-003117ELLIOTT FARMS ” R-416608 04/21/21 Exhibit B BMP Detail Exhibit C Correspondence Exhibit D Site Inspection Form Exhibit E Construction Stormwater General Permit (CSWGP) Exhibit F 303(d) List Waterbodies/TMDL Waterbodies Information Exhibit G Contaminated Site Information Exhibit H Engineering Calculations 21397.002-TIR.docx 8.0 CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN (CSWPP) ANALYSIS AND DESIGN A. Erosion and Sediment Control (ESC) Plan Analysis and Design The erosion and sediment control plans were prepared in accordance with the 2009 King County Surface Water Design Manual, and standard industry practices throughout the construction process to limit the amount of sediment traveling into the downstream systems. The BMPs being proposed include a stabilized rocked construction entrance, silt fence where needed, NGPE fencing, straw mulch for the areas that reach final grade in the lot areas, V-ditches with rock check dams, temporary sediment ponds, and hydro seeding. Clearing limits are shown on the final engineering plans. Two temporary sediment ponds have been placed at the downstream drainage points of the project. A sediment pond (sediment pond #1) is located at the northwest corner and one a sediment trap is located at the northeast corner (sediment trap #2). Sediment pond #1 has a basin area of 3.29 acres. Sediment trap #1 has a basin area of 1.43 acres. The WWHM program was used to size the sediment pond and sediment trap. The full basin area was assumed to be landscape (grass) area. The 2-year predicted flow rate was used to size the sediment trap and the 10-year flow rate was used to size the sediment pond. Sediment Trap #1 (NE CORNER): S.A. = 2 x Q2/0.00096 = 2080 square feet per cfs of inflow Q2 = 0.134 (See WWHM calculations) S.A. = 0.134 x 2080 = 279 sf S.A. Required = 279 sf S.A. Provided = 1,015 sf Sediment Pond #1 (NW corner): S.A. = 2 x Q10/0.00096 = 2080 square feet per cfs of inflow Q10 = 0.745 (See WWHM calculations) S.A. = 0.745 x 2080 = 396 sf S.A. Required = 1,550 sf S.A. Provided = 1,630 sf · Find Size of Dewatering Orifice: A0 = SA(2H)0.5 SA = 1,550 sf 0.6 x 3,600Tg0.5 H = 3.5 feet T = 24 hours G = 32.2 ft/s2 A0 = 1,550(2 x 3.5)0.5 0.6 x 3,600 x 24 x 32.20.5 A0 = 0.0139 sf 21397.002-TIR.docx · Find Orifice Diameter: D = 24 x p 0A =13.54 x 0A 13.54 x √0.0139 D = 1.60 inches B. Stormwater Pollution Prevention and Spill (SWPPS) Plan Design A Stormwater Pollution Prevention Plan (SWPPP) will be prepared with the final engineering plan approval process. The SWPPP report will be prepared following the Department of Ecology (DOE) format and will be kept on-site during all construction activities. The SWPPP report will include a narrative discussion of construction BMP’s that will be implemented during construction, based on the 13 required elements as defined by DOE. The SWPPP report will also outline inspection, monitoring, and reporting requirements to meet the requirements of the NPDES permit. A Stormwater Pollution Prevention and Spill (SWPPS) Site Plan is also included in the construction plans. This plan provided suggested locations for: · equipment parking/maintenance areas · chemical storage areas with secondary containment · construction materials and construction waste storage areas · truck wheel washout areas This plan also provides general locations of erosion control such as silt fencing, temporary sediment traps, construction entrances, and clearing limits. The site is generally underlain by alluvial soils. A seasonally high groundwater table will be present during the wet winter and early spring months. Potential Spill Sources or Releases Potential spill sources during construction will include materials and equipment brought on- site. Potential spill sources include; fueling, lubricating oil, hydraulic oil, backhoes, bulldozers, water trucks, support trucks, lighting units, pumps, and generators. Equipment staging and maintenance areas for fueling, hazardous materials, and hazardous waste materials have been designated on the SWPPS. Construction debris will be present during demolition of the existing on-site buildings. No fuel tanks, gasoline, oils and hydraulic fuels will be stored on-site. Control Pollutants Pollutants other than sediment will be controlled as part of the implemented SWPPS plan. Maintenance and repair of heavy equipment and vehicles that may result in discharge or spillage of pollutants to the ground or surface water runoff will be conducted using spill prevention measures. Contaminated surfaces will be cleaned immediately following any discharge or spill incident. Spills will be reported within 24 hours. Emergency repairs may be performed on-site using temporary plastic placed beneath and, if raining, over the vehicle. 21397.002-TIR.docx Concrete truck chutes and pumps shall be washed out only into formed areas awaiting installation of concrete or asphalt. Unused concrete remaining in the truck and pump shall be returned to the originating batch plant for recycling. Hand tools including, but not limited to, screeds, shovels, rakes and trowels shall be washed off only into formed areas awaiting installation of concrete or asphalt. When no formed areas are available, washwater and leftover product shall be contained in a lined container or in a sump designed to receive the materials. Contained concrete shall be disposed of in manner that does not violate groundwater or surface water quality standards. Recommended BMP’s include Concrete Handling (BMP C151) Spill Prevention and Containment The following is a list of BMP’s that will be used for the project. · Store and maintain equipment in a designated area. · Reduce the amount of hazardous materials and waste by substituting non-hazardous or less hazardous materials. · Use secondary containment (drain pan) to catch spills when removing or changing fluids. · Use proper equipment (pumps, funnels) to transfer fluids · Keep spill kits readily accessible. · Check incoming vehicles for leaking oil and fluids. · Transfer used fluids and oil filters to waste or recycling drums. · Inspect equipment immediately, if necessary. · Implement a preventative maintenance schedule for equipment and vehicles. · Perform fueling in designated fueling area. · Do not “top-off” tanks · Use secondary containment (drain pan) to catch spills. · Keep spill kits readily accessible. · Inspect fueling areas routinely for leaks and spills. · Monitor pollution prevention BMP’s and maintain records/reports of all inspections using the worksheets at the end of this section. Spill Response Response in the first 15 minutes is critical to minimize the impacts to human health and the environment and to minimize property damage and cleanup costs. The contractor will respond immediately to spills and regulated materials. Spill response equipment shall be stored in spill response kits located in a clearly marked and accessible area. The standard approach toward spill response will be as follows: · Stop operations. · Stop the source of the spill. · Use appropriate materials to absorb, berm, or cover the area to prevent further contamination. 21397.002-TIR.docx · Notify the construction manager. · Determine the method of clean up required. All methods shall comply with the state or local requirements to spill response. · Contact a cleanup response firm if necessary. Contact Personnel The designated personnel responsible for managing, implementing and maintaining this SWPPS plan include: Client: Quadrant Homes CECL: - TBD The contractor – TBD A SWPPP report has also been prepared following the Department of Ecology (Ecology) format and will be kept on-site during all construction activities. The SWPPP report includes a narrative discussion of construction BMP’s that will be implemented during construction, based on the 12 required elements as defined by Ecology. The SWPPP report also outlines inspection, monitoring, and reporting requirements to meet the requirements of the NPDES permit. WWHM2012 PROJECT REPORT SEDIMENT POND CALULATIONSSEDIMENT POND CALCULATIONS 21397-Tesc Flows 2/26/2021 9:05:59 AM Page 2 General Model Information Project Name:21397-Tesc Flows Site Name:Elliot Farms Site Address: City: Report Date:2/26/2021 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2018/03/02 Version:4.2.14 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year Low Flow Threshold for POC2:50 Percent of the 2 Year High Flow Threshold for POC2:50 Year 21397-Tesc Flows 2/26/2021 9:05:59 AM Page 3 Landuse Basin Data Predeveloped Land Use 21397-Tesc Flows 2/26/2021 9:05:59 AM Page 4 Mitigated Land Use West sediment pond Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 3.29 Pervious Total 3.29 Impervious Land Use acre Impervious Total 0 Basin Total 3.29 Element Flows To: Surface Interflow Groundwater 21397-Tesc Flows 2/26/2021 9:05:59 AM Page 5 East sediment trap Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 1.43 Pervious Total 1.43 Impervious Land Use acre Impervious Total 0 Basin Total 1.43 Element Flows To: Surface Interflow Groundwater 21397-Tesc Flows 2/26/2021 9:05:59 AM Page 7 Mitigated Routing SEDIMENT POND #1 SEDIMENT TRAP #1 21397-Tesc Flows 2/26/2021 9:06:15 AM Page 12 Mitigated Schematic 21397-Tesc Flows 12/4/2020 2:36:54 PM Page 20 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. 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