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Home My WebLink AboutF_Cherie Lane_SWPPP_10-14-2020Stormwater Pollution Prevention Plan (SWPPP) for Cherie Lane Short Plat Prepared for: The Washington State Department of Ecology Northwest Regional Office 3190 160th Ave SE Bellevue, WA 98008 Permittee / Owner Developer Operator / Contractor Ram Singh; 10616 SE 268th Street, Kent, WA 98030 Ram Singh; 10616 SE 268th Street, Kent, WA 98030 TBD Certified Erosion and Sediment Control Lead (CESCL) Name Organization Contact Phone Number TBD TBD TBD SWPPP Prepared By Name Organization Contact Phone Number Edward Mecum Encompass Engineering & Surveying (425) 392-0250 SWPPP Preparation Date 9/2/2020 Project Construction Dates Activity / Phase Start Date End Date Site Grading To Be Determined To Be Determined Utilities Installation To Be Determined To Be Determined Surface Finishing/Paving To Be Determined To Be Determined Final Stabilization To Be Determined To Be Determined APPROVED 10/14/2020 msippo DEVELOPMENT ENGINEERING DIVISION doe coverage not required due to construction limits being 1/2 acre. final swppp to be onsite with contractor information written in once construction begins. TABLE OF CONTENTS PROJECT INFORMATION (1.0) ........................................................................................................................ 4 CONSTRUCTION STORMWATER BEST MANAGEMENT PRACTICES (BMPS) (2.0) ............................. 7 POLLUTION PREVENTION TEAM (3.0) ........................................................................................................ 23 MONITORING AND SAMPLING REQUIREMENTS (4.0) ............................................................................. 24 DISCHARGES TO 303(D) OR TOTAL MAXIMUM DAILY LOAD (TMDL) WATERBODIES (5.0) ........... 27 REPORTING AND RECORD KEEPING (6.0) ................................................................................................ 28 List of Tables 1. Summary of Site Pollutant Constituents 2. Pollutants 3. pH-Modifying Sources 4. Management 5. Team Information 6. Turbidity Sampling Method 7. pH Sampling Method List of Appendices A. Site Map B. BMP Detail C. Site Inspection Form D. Sediement Tank/Pump Design Calculations List of Acronyms and Abbreviations Acronym / Abbreviation Explanation 303(d) Section of the Clean Water Act pertaining to Impaired Waterbodies BFO Bellingham Field Office of the Department of Ecology BMP(s) Best Management Practice(s) CESCL Certified Erosion and Sediment Control Lead CO2 Carbon Dioxide CRO Central Regional Office of the Department of Ecology CSWGP Construction Stormwater General Permit CWA Clean Water Act DMR Discharge Monitoring Report DO Dissolved Oxygen Ecology Washington State Department of Ecology EPA United States Environmental Protection Agency ERO Eastern Regional Office of the Department of Ecology ERTS Environmental Report Tracking System ESC Erosion and Sediment Control GULD General Use Level Designation NPDES National Pollutant Discharge Elimination System NTU Nephelometric Turbidity Units NWRO Northwest Regional Office of the Department of Ecology pH Power of Hydrogen RCW Revised Code of Washington SPCC Spill Prevention, Control, and Countermeasure su Standard Units SWMMEW Stormwater Management Manual for Eastern Washington SWMMWW Stormwater Management Manual for Western Washington SWPPP Stormwater Pollution Prevention Plan TESC Temporary Erosion and Sediment Control SWRO Southwest Regional Office of the Department of Ecology TMDL Total Maximum Daily Load VFO Vancouver Field Office of the Department of Ecology WAC Washington Administrative Code WSDOT Washington Department of Transportation WWHM Western Washington Hydrology Model Project Information (1.0) Project/Site Name: Cherie Lane Short Plat Street/Location: 34XX Talbot Road S (TPN 302305-9108) City: Renton State: WA Zip code: 98055 Subdivision: N/A Receiving waterbody: Panther Creek Existing Conditions (1.1) Total acreage (including support activities such as off-site equipment staging yards, material storage areas, borrow areas). Total acreage: 2.67 AC Disturbed acreage: 0.79 AC Existing structures: None. Landscape topography: The existing topography of the construction area on the lot has slopes which range between 8% to 25%. The site is currently undeveloped and predominately forested. The existing utility easement along the north 30-feet of the site is cleared and partially covered with an existing gravel driveway. Drainage patterns: Runoff from the site generally sheet flows to the west toward an existing roadside ditch along Talbot Road South. The ditch conveys water to the south where it flows into an existing Catch Basin. Stormwater then flows to the west under Talbot Road S where it is discharged at Outfall OUT-0498. Stormwater is conveyed to the west via a shallow channel until it is ultimately discharged to Pather Creek. An Off-site Analysis has been prepared for the site and is included in the Technical Information Report. Existing Vegetation: Grass, vegetation, trees. Critical Areas: The parcel contains an extensive unsubmerged Category IV wetland and associated 50-foot buffer located centrally on the property. In addition, two off-site wetlands have been identified. A smaller Category IV wetland with associated 50-foot buffer is located north of the site, and a Category III wetland with associated 75-foot buffer has been identified south of the site. The southwest portion of the site is located within a Coal Mine Hazard Area and contains four (4) small underground coal mines ranging from low to higher risk. Higher risk areas present a potential risk for subsidence or collapse; therefore, no development should take place in these areas unless proper structural controls are in place. Appurtenances such as driveways, outbuilding, and cleared lawn may be constructed within the moderate hazard areas. Structural development is allowed within the low hazard areas with proper mitigation. All critical areas and their associated buffers have been identified on the Site Plan and Civil Engineering Plan Set. List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the receiving waterbody: Temperature 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 Gasoline Construction Vehicles Proposed Construction Activities (1.2) Description of site development: The project site is located in the City of Renton on tax parcel number 302305-9108. The site is 114,814 square-feet (2.64 Acres) and presently is undeveloped and predominately forested. The site is accessed via an existing 30-foot utility easement between Talbot Road South and South 34th Place. The easement contains storm, sewer, and gas utilities extending from Talbot Road South to the Cherie Lane II housing development located on South 34th Place. The project proposes the development of two (2) single-family lots and a Private Critical Area Tract (Tract A) within the 114,814 SF (2.64 Acres) parcel. Lot 1 is 10,665 SF (0.24 Acres) and is located along the eastern portion of the site with driveway access off of South 34th Place. The concrete driveway for Lot 1 is currently being constructed under a separate approved building permit for Parcel # 302305-9022. As part of the Cherie Lane project, frontage improvements for South 34th Place including 4.5’ sidewalk, 6” curb, and gutter are proposed. Lot 2 is 40,197 SF (0.92 Acres) and is located on the western portion of the site with driveway access off of Talbot Road South. An asphalt driveway with a slope of 15% and hammerhead turnaround will be constructed off of Talbot Road South for access to Lot 2. In addition, structural retaining walls and fences will be constructed along the northern and southern limits of the proposed driveway cut for Lot 2. The remaining 63,951 SF (1.47 Acres) located centrally on the site will be designated as a Private Critical Area Tract (Tract A). Description of construction activities: The development of the site will include site gradin, utilities installation, and surface finishing/paving. Utilities will include stormwater, sanitary sewer, potable water, and all private utilities. Description of site drainage: Stormwater runoff from the proposed development will be managed as follows: • Lot 1: The concrete driveway on Lot 1 is being constructed under a separate approved building permit for Parcel # 302305-9022. Based on the available records, the driveway is being constructed to drain to the South 34th Place stormwater system, east of Lot 1. In addition, the proposed frontage improvements for South 34th Place (4.5’ sidewalk, 6” curb, and gutter) will be routed to the existing stormwater system for South 34th Place. All new pervious surface created on Lot 1 will be fully dispersed over the 50-foot wetland buffer west of Lot 1. • Lot 2: Runoff from the proposed asphalt driveway on Lot 2 will be conveyed and discharged to the existing storm system for Talbot Road South. Prior to being discharged to the existing stormwater system, driveway runoff will be treated for water quality with the proposed Oldcastle BioPod. All new pervious surface created on Lot 2 will follow the natural drainage pattern and sheet flow toward the Talbot Road South stormwater ditch. • Critical Area Tract A: No development is proposed within the Private Critical Area Tract (Tract A). Stormwater will follow the natural drainage pattern and sheet flow toward Talbot Road South. Please refer to the Developed Conditions Map included in Appendix A for the location of the proposed stormwater facilities. Description of final stabilization: Final stabilization will include revegetation and landscaping of exposed areas, as well as paving of roads and sidewalks. Contaminated Site Information: There are no known contaminated soils on site. Construction Stormwater Best Management Practices (BMPs) (2.0) The SWPPP is a living document reflecting current conditions and changes throughout the life of the project. These changes may be informal (i.e. hand-written notes and deletions). Update the SWPPP when the CESCL has noted a deficiency in BMPs or deviation from original design. The 12 Elements (2.1) Element 1: Preserve Vegetation / Mark Clearing Limits (2.1.1) The limits of clearing and grading will be marked in several ways around the site depending on the location. Combination high visibility orange/silt fencing will be installed along clearing limits. Several trees are scheduled to be retained on the site. Trees that are within the clearing limits will need to be protected with a tree protection fence. During the clearing effort, the topsoil and duff materials should be kept in a separate stockpile for future use to help promote grass growth during project close out. List and describe BMPs: BMP C101: Preserving Natural Vegetation BMP C102: Buffer Zones BMP C103: High Visibility Fence BMP C233: Silt Fence Installation Schedules: Marking the clearing limits is one of the first things to be accomplished on the construction site. Prior to any site clearing or grading, areas that are to remain undisturbed during project construction will be delineated. Once all plat construction is complete the clearing limit BMPs may be removed as approved by the City. Inspection and Maintenance plan: The clearing limits should be observed on a daily basis and thoroughly inspected weekly to ensure they are in place and functioning to protect areas that are not being cleared. Any damaged or missing portions of the clearing limit BMPs should be repaired or replaced immediately. Responsible Staff: CESCL Element 2: Establish Construction Access (2.1.2) The existing driveway within the utility easement for Lot 1 will be utilized to access the site from S 34th Place. A separate construction entrance off of Talbot Road will be established for the Lot 2 construction area. If construction vehicles are observed tracking soil onto the roads, a wheel wash will be installed at the construction access point. List and describe BMPs: BMP C105: Stabilized Construction Entrance BMP C106: Wheel Wash (if necessary) Installation Schedules: A temporary stabilized construction entrance will be constructed on-site prior to initiating other construction activities. A wheel wash should be installed as deemed necessary. Inspection and Maintenance plan: The construction entrance will be observed daily for any deficiencies such as excess dirt or mud. Also, the public roads will be observed on a continual basis during vehicle exiting to ensure no soil deposits are being tracked onto the roadway. If the construction entrance proves inadequate to prevent soil from being deposited onto the roadway, additional measures will be necessary, including street sweeping and the use of a wheel wash for pervasive failures. Other stabilized areas will be inspected regularly, especially after large storm events. Any damaged or missing portions of the site BMPs should be repaired or replaced immediately. Responsible Staff: CESCL Element 3: Control Flow Rates (2.1.3) At all times, flow rates will be controlled for this project. Natural drainage patterns will be protected as much as possible during construction, and concentrated flow should not be permitted. Properties and waterways downstream from development sites will be protected from erosion due to increases in the volume, velocity, and peak flow rate of stormwater runoff from the project site. Will you construct stormwater retention and/or detention facilities? Yes No A 4-foot diameter sump and a sump pump with a capacity of 83 GPM at a head of 50 feet is proposed to convey stormwater runoff from the Talbot Road South ditch to a minimum 5,625 GAL temporary sediment tank. The temporary sediment tank will be installed on-site upslope of Talbot Road South to control construction stormwater runoff. An overflow hose from the sediment tank to an existing catch basin with inlet protection will be provided. Please refer to the site plan in Appendix A and the Sediment Tank/Pump Design Calculations in Appendix D for additional details. 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 C220: Inlet Protection BMP C240: Sediment Trap Installation Schedules: Construction of the BMPs and associated infrastructure is scheduled for the beginning of the project. The measures described above are required throughout construction. Inspection and Maintenance plan: The BMPs should be inspected on a weekly basis to verify that the capacity has not diminished due to sedimentation in such a way that the BMP loses efficiency. Sediment will be removed from the sediment tank when it reaches 1-foot in depth. Any damaged or missing portions of the site BMPs should be repaired or replaced immediately. Responsible Staff: CESCL Element 4: Install Sediment Controls (2.1.4) As described in detail in Element 3, areas of disturbed soil will be routed to an on-site temporary sediment tank via a sump pump located near Talbot Road South. The sediment tank will have an overflow to an existing stormwater catch basin. In order to protect the catch basin inlet from sediment, inlet protection will be provided. Please refer to the site plan in Appendix A and the Sediment Tank/Pump Design Calculations in Appendix E for additional details. In addition, silt fence will be installed along the downstream perimeter of the construction limits to minimize sediment discharges from the site. List and describe BMPs: BMP C220: Inlet Protection BMP C233: Silt Fence BMP C240: Sediment Trap Installation Schedules: Implimentation of sediment control BMPs is scheduled for the beginning of the project. These BMPs will be functional before other land disturbing activities take place. The measures described above are required throughout construction. Inspection and Maintenance plan: The sediment control facilities should be inspected on a weekly basis to verify that the capacity has not diminished due to sedimentation in such a way that the BMP loses efficiency. Any damaged or missing portions of the site BMPs should be repaired or replaced immediately. Responsible Staff: CESCL Element 5: Stabilize Soils (2.1.5) Soils on site will be stabilized as appropriate through a variety of methods. These BMPs will be implemented when soil is to remain unworked or at the threat of rain throughout the project. Stock piles will be covered with plastic sheeting unless an extended period of storage is expected, in which case the stockpiles should be seeded and covered with mulch and an erosion control net. Runoff from plastic sheeting will be directed to an acceptable discharge location. During the hot summer months, dust control is necessary. This is accomplished by applying water to dry soils routinely. The water should not be applied in a way that creates runoff, however. 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: May 2020 End date: May 2021 Will you construct during the wet season? Yes No List and describe BMPs: BMP C120: Temporary and Permanent Seeding BMP C121: Mulching BMP C122: Nets and Blankets BMP C123: Plastic Covering BMP C140: Dust Control Installation Schedules: Soil Stabilization BMPs will be applied as deemed necessary. Exposed areas should be evaluated and covered to prevent impacts to roadways, drainage ways, or surface waters. Seeding will be used throughout the project on disturbed areas that have reached final grade or that will remain unworked for more than 30 days. Inspection and Maintenance plan: Soil Stabilization BMPs should be reviewed daily and thoroughly inspected weekly and after each rainfall event to ensure they are functioning appropriately. All deficiencies will be repaired or replaced in accordance with the number of days exposed soils may be left exposed. Any damaged or missing portions of the site BMPs should be repaired or replaced immediately. Responsible Staff: CESCL Element 6: Protect Slopes (2.1.6) There are no existing steep slopes on the site, and no slopes are proposed to be constructed or altered by the development. Will steep slopes be present at the site during construction? Yes No List and describe BMPs: None Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: N/A Element 7: Protect Drain Inlets (2.1.7) Catch basin inserts will be installed on all existing and proposed on-site and downstream catch basins to which the project is tributary to. List and describe BMPs: BMP C220: Inlet Protection Installation Schedules: Storm drain inlet protection will be installed prior to the start of construction for all existing inlets. Constructed onsite catch basins will be protected prior to the first gravel lift. Inspection and Maintenance plan: All facilities should be inspected weekly and after every rainfall event. BMPs showing 1/3 of their capacity full of sediment should have the sediment removed or the unit replaced. Any damaged or missing portions of the site BMPs should be repaired or replaced immediately. Responsible Staff: CESCL Element 8: Stabilize Channels and Outlets (2.1.8) There are no existing channels and outlets on the site, and no temporary or permanent channels/outlets are proposed the construction. List and describe BMPs: None Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: N/A 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) Gasoline in vehicles Concrete poured in place There are no known pollutants contained on the existing site. During construction, the contractor will need to conduct maintenance, fueling, and repair of heavy equipment and vehicles off-site as spills of hazardous materials could result in an environmental event. If a wheel wash is incorporated into the protection plan, the contractor will discharge wheel wash wastewater to a separate on-site treatment system that prevents discharge to surface water, such as closed-loop recirculation, or to the sanitary sewer with Soos Creek Sewer District approval. Concrete will be handled in ways to eliminate concrete, concrete process water, and concrete slurry from entering waters of the state. List and describe BMPs: BMP C151: Concrete Handling BMP C152: Sawcutting and Surfacing Pollution Prevention BMP C153: Material Delivery, Storage and Containment BMP C154: Concrete Washout Area BMP C251: Construction Stormwater Filtration Installation Schedules: BMPs will be implemented at the beginning of construction and as needed throughout the project. Concrete washout BMPs will be in place prior to the commencement of concrete work. Inspection and Maintenance plan: Inspection of the concrete washout area should be done weekly and prior to expected concrete pours. Washout facilities must be cleaned, or new facilities must be constructed and ready for use one the washout is 75% full. Secondary containment facilities should be inspected daily and repaired or replaced as necessary. Contaminated surfaces will be cleaned immediately following any discharge or spill incident. Any damaged or missing portions of the site BMPs should be repaired or replaced immediately. Responsible Staff: CESCL Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site? Yes No List and describe BMPs:None Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: N/A Will wheel wash or tire bath system BMPs be used during construction? Yes No List and describe BMPs: BMP C106: Wheel Wash Installation Schedules: Wheel wash systems will be installed if deemed necessary by the contractor when the stabilized construction entrance is not preventing sediment from being tracked off-site. Inspection and Maintenance plan: Wheel wash systems will be inspected weekly and repaired as necessary. Wash water should be changed a minimum of once per day. Responsible Staff: CESCL 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 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 Recycled concrete Other (i.e. calcium lignosulfate) [please describe] During this construction activity, the pH levels of stormwater runoff must be monitored. If pH levels exceed 8.5, the level will need to be corrected. The use of CO2 per WDOE standards will rapidly neutralize the water and make it suitable for discharge. List and describe BMPs: BMP C252: Treating and Disposing of High pH Water Installation Schedules: pH neutralization using CO2 will be implemented as necessary to correct pH levels in excess of 8.5. Inspection and Maintenance plan: Operators will keep written records related to treatment as detailed in the Stormwater Management Manual for Western Washington. A copy of this record should be given to the client/contractor who should retain the record for three years. Responsible Staff: 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. Element 10: Control Dewatering (2.1.10) Dewatering of the temporary sediment tank will be required upon completion of construction. Discharge from the dewatering process will be conveyed to the existing stormwater catch basin within the utility easement, which is adjacent to the proposed sediment tank location. An insert will be installed in the receiving catch basin to protect the inlet from sedimentation. Please refer to the site plan in Appendix A and the Sediment Tank/Pump Design Calculations in Appendix E for additional details. List and describe BMPs: BMP C220: Inlet Protection Installation Schedules: Storm drain inlet protection will be installed prior to the start of construction and dewatering activities. Inspection and Maintenance plan: All facilities should be inspected weekly and after every rainfall event. BMPs showing 1/3 of their capacity full of sediment should have the sediment removed or the unit replaced. Any damaged or missing portions of the site BMPs should be repaired or replaced immediately. Responsible Staff: CESCL Element 11: Maintain BMPs (2.1.11) All temporary and permanent Erosion and Sediment Control (ESC) BMPs will be maintained and repaired as needed to ensure continued performance of their intended function. Maintenance and repair will 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 will be removed within 30 days after final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment will be stabilized on-site or removed. Disturbed soil resulting from removal of either BMPs or vegetation will 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 will be examined and restored to full operating condition. If sediment enters these BMPs during construction, the sediment will be removed and the facility will be returned to conditions specified in the construction documents. List and describe BMPs: BMP C150: Materials on Hand BMP C160: Certified Erosion and Sediment Control Lead Responsible Staff: CESCL 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 Coordinate with subcontractors and laborers to ensure the SWPPP measures are followed. • Documentation and reporting: o Document site inspections and monitoring in accordance with specific BMP conditions and City of Renton requirements. • Maintain an updated SWPPP. o The SWPPP will be updated, maintained, and implemented in accordance with City of Renton requirments. Coordinate SWPPP pla updates with the site inspector. 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 4 – 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) List and describe BMPs: BMP C150: Materials on Hand BMP C160: Certified Erosion and Sediment Control Lead BMP C162: Scheduling Responsible Staff: CESCL Element 13: Protect Low Impact Development (LID) BMPs (2.1.13) The native vegetaion within the proposed on-site Native Growth Retention Area (NGRA) will be preserved to the maximum extent feasible. No disturbance of vegetation or soils within the proposed NGRA is permitted. Please refer to the site plan in Appendix A for additional details. List and describe BMPs: BMP C103: High Visibility Fence BMP C233: Silt Fence Installation Schedules: Marking the clearing limits is one of the first things to be accomplished on the construction site. Prior to any site clearing or grading, areas that are to remain undisturbed during project construction will be delineated. High visibility fencing should be installed around the limits of the proposed NGRA prior to the start of construction. Silt fencing should be installed upstream of the NGRA area to protect it from construction sediment. Inspection and Maintenance plan: All facilities should be inspected weekly and after every rainfall event. The clearing limits should be observed on a daily basis and thoroughly inspected weekly to ensure they are in place and functioning to protect the intended areas. Any damaged or missing portions of the site BMPs should be repaired or replaced immediately. On-site stormwater management BMPs should be restored to design conditions at the end of the project. Responsible Staff: CESCL Pollution Prevention Team (3.0) Table 5 – Team Information Title Name(s) Phone Number Certified Erosion and Sediment Control Lead (CESCL) TBD TBD Resident Engineer Edward Mecum (425) 392-0250 Emergency Ecology Contact TBD TBD Emergency Permittee/ Owner Contact Ram Singh (253) 332-5692 Non-Emergency Owner Contact Ram Singh (253) 332-5692 Monitoring Personnel TBD TBD Ecology Regional Office Northwest (425) 649-7000 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 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. Complete the following paragraph for sites that discharge to impaired waterbodies for fine sediment, turbidity, phosphorus, or pH: The receiving waterbody, Panther Creek, is not a 303(d) listed waterbody and it is not impared for sediment, turbidity, phosphorus, or pH. 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). 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 City of Renton requirments. Sampling will be conducted at all discharge points at least once per calendar week. Method for sampling turbidity: Table 6 – 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. 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 City of Renton Code. 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. 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 7 – pH Sampling Method pH meter X pH test kit Wide range pH indicator paper 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 List the impairment(s): N/A The receiving waterbody, Panther Creek, is not a 303(d) listed waterbody and is not impared for turbidity, fine sediment, phosphorus, or pH. TMDL Waterbodies (5.2) Waste Load Allocation for discharges: No known waste load allocation for discharges. 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 City of Renton code. Permit documentation to be retained on-site: • 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 City of Renton Code. 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. Appendix A – Site Map TALBOT ROADS 34TH PLLOT 1TRACT ALOT 2TESC LEGENDNORTHSURVEY LEGEND▪▪▪▪▪▪ncompassENGINEERING & SURVEYINGEKnow what'sCallbelow.before you dig.REROSION CONTROL GENERAL NOTESCONSTRUCTION SEQUENCEEROSION PROTECTION NOTE:SEDIMENT TANK CALCULATIONS:TESC LEGENDAROBORIST NOTE: Appendix B – BMP Detail 1/17/2020 BMP C101: Preserving Natural Vegetation https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…1/3 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C101: Preserving Natural Vegetation 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 watercourses or swales, and on building sites in wooded areas. As required by local governments. 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: 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. 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: 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. Grade Changes - Changing the natural ground level will alter grades, which affects the plant's ability to obtain the necessary air, water, and minerals. Minor fills usually do not cause problems although sensitivity 1/17/2020 BMP C101: Preserving Natural Vegetation https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…2/3 between species does vary and should be checked. Trees can typically tolerate fill of 6 inches or less. For shrubs and other plants, the fill should be less. When there are major changes in grade, it may become necessary to supply air to the roots of plants. This can be done by placing a layer of gravel and a tile system over the roots before the fill is made. The tile system should be laid out on the original grade leading from a dry well around the tree trunk. The system should then be covered with small stones to allow air to circulate over the root area. Lowering the natural ground level can seriously damage trees and shrubs. The highest percentage 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 undisturbed, gently sloping mound. To increase the chances for survival, it is best to limit grade changes and other soil disturbances to areas outside the dripline of the plant. 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: 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. Backfill the trench as soon as possible. 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: 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. 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. 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. 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 serious 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 1/17/2020 BMP C101: Preserving Natural Vegetation https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…3/3 Inspect flagged and/or fenced areas regularly to make sure flagging or fencing has not been removed or damaged. If the flagging or fencing has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. If tree roots have been exposed or injured, “prune” cleanly with an appropriate pruning saw or loppers 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. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 1/17/2020 BMP C102: Buffer Zones https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…1/2 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C102: Buffer Zones 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 completely 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 expanded 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 preservation of natural vegetation, they should be arranged in clumps or strips. They can be used to protect natural swales and incorporated into the natural landscaping area. Design and Installation Specifications Preserving natural vegetation or plantings in clumps, blocks, or strips is generally the easiest and most successful method. Leave all unstable steep slopes in natural vegetation. 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. 1/17/2020 BMP C102: Buffer Zones https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…2/2 Alternatively, wire-backed silt fence on steel posts is marginally effective. Flagging alone is typically not effective. Keep all excavations outside the dripline of trees and shrubs. Do not push debris or extra soil into the buffer zone area because it will cause damage by burying and smothering vegetation. 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 undisturbed. 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. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 1/17/2020 BMP C103: High-Visibility Fence https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…1/2 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C103: High-Visibility Fence BMP C103: High-Visibility Fence Purpose High-visibility fencing is intended to: Restrict clearing to approved limits. Prevent disturbance of sensitive areas, their buffers, and other areas required to be left undisturbed. Limit construction traffic to designated construction entrances, exits, or internal roads. 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: At the boundary of sensitive areas, their buffers, and other areas required to be left uncleared. 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. Maintenance Standards 1/17/2020 BMP C103: High-Visibility Fence https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…2/2 If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 1/17/2020 BMP C105: Stabilized Construction Access https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…1/4 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C105: Stabilized Construction Access BMP C105: Stabilized Construction Access Purpose Stabilized construction accesses are established to reduce the amount of sediment transported onto paved roads outside the project site by vehicles or equipment. This is done by constructing a stabilized pad of quarry spalls at entrances and exits for project sites. Conditions of Use Construction accesses shall be stabilized wherever traffic will be entering or leaving a 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 residence, 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 materials 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 concrete, cement, or calcium chloride for construction access stabilization because these products raise pH levels in stormwater and concrete discharge to waters of the State is prohibited. 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 Construction Access Geotextile Standards. Table II-3.2: Stabilized Construction Access Geotextile Standards 1/17/2020 BMP C105: Stabilized Construction Access https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…2/4 Geotextile Property Required ValueGeotextile Property Required Value Grab Tensile Strength (ASTM D4751)200 psi min. Grab Tensile Elongation (ASTM D4632)30% max. Mullen Burst Strength (ASTM D3786-80a)400 psi min. AOS (ASTM D4751)20-45 (U.S. standard sieve size) 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. Fencing (see BMP C103: High-Visibility Fence) shall be installed as necessary to restrict traffic to the construction access. 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. 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 performance 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 Standard Specifications for Road, Bridge, and Municipal Construction Section 9-03.9(1) (WSDOT, 2016) for ballast except for the following special requirements. The grading and quality requirements are listed in Table II-3.3: Stabilized Construction Access Alternative Material Requirements. Table II-3.3: Stabilized Construction Access Alternative Material Requirements Sieve Size Percent Passing 1/17/2020 BMP C105: Stabilized Construction Access https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…3/4 Sieve Size Percent Passing 2½″99-100 2″65-100 ¾″40-80 No. 4 5 max. No. 100 0-2 % Fracture 75 min. All percentages are by weight. The sand equivalent value and dust ratio requirements do not apply. 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. 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 replacement/cleaning of the existing quarry spalls, street sweeping, an increase in the dimensions of the access, or the installation of BMP C106: Wheel Wash. Any sediment that is tracked onto pavement shall be removed by shoveling or street sweeping. 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 ineffective and there is a threat to public safety. If it is necessary to wash the streets, the construction of a small sump to contain the wash water shall be considered. The sediment would then be washed into the sump where it can be controlled. Perform street sweeping by hand or with a high efficiency sweeper. Do not use a non-high efficiency mechanical sweeper because this creates dust and throws soils into storm systems or conveyance ditches. Any quarry spalls that are loosened from the pad, which end up on the roadway shall be removed immediately. 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. Upon project completion and site stabilization, all construction accesses intended as permanent access for maintenance shall be permanently stabilized. Figure II-3.1: Stabilized Construction Access 1/17/2020 BMP C105: Stabilized Construction Access https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…4/4 g pdf download 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-permittee-guidance- resources/Emerging-stormwater-treatment-technologies Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 D EPARTMENT OF ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Stabilized Construction Access Revised June 2018 NOT TO SCALE Existin g R o a d Notes: 1. Driveway shall meet the requirements of the permitting agency. 2. It is recommended that the access be crowned so that runoff drains off the pad. Install driveway culvert if there is a roadside ditch present 4" - 8" quarry spalls Geotextile 12" minimum thickness 15' min. 100' min. Provide full width of ingress/egress area 1/17/2020 BMP C106: Wheel Wash https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…1/2 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C106: Wheel Wash 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 Use a wheel wash when BMP C105: Stabilized Construction Access is not preventing sediment from being tracked off site. Wheel washing is generally an effective BMP when installed with careful attention to topography. For example, a wheel wash can be detrimental if installed at the top of a slope abutting a right-of-way where the water from the dripping truck can run unimpeded into the street. 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. 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. Wheel washes may use closed-loop recirculation systems to conserve water use. Wheel wash wastewater shall not include wastewater from concrete washout areas. 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 installation 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 material or 8 inches over a good subgrade is recommended to pave the wheel wash. Use a low clearance truck to test the wheel wash before paving. Either a belly dump or lowboy will work well to test clearance. 1/17/2020 BMP C106: Wheel Wash https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…2/2 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 sediment. 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-permittee-guidance- resources/Emerging-stormwater-treatment-technologies Figure II-3.2: Wheel Wash pdf download Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 D EPARTMENT OF ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Wheel Wash Revised June 2016 NOT TO SCALE Notes: 1. Build 8' x 8' sump to accomodate cleaning by trackhoe. 6" sewer pipe with butterfly valves 8' x 8' sump with 5' of catch 3" trash pump with floats on suction hose 2" schedule 40 1 12 " schedule 40 for sprayers midpoint spray nozzles, if needed 15' ATB apron to protect ground from splashing water 6" sleeve under road 6" ATB construction entrance Asphalt curb on the low road side to direct water back to pond Ball valves 2% slope 5:1 slope 1:1 slope 5:1 slope 2% slope A A Plan View 15'15'20'15'50' Curb 6" sleeve Elevation View Locate invert of top pipe 1' above bottom of wheel wash 8' x 8' sump 5' Drain pipe 12' 3' 18' Water level 1:1 slope Section A-A 11/14/2019 BMP C120: Temporary and Permanent Seeding https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…1/6 You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C120: Temporary and Permanent Seeding 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 protection. 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 stabilization 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 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 before water flow; install sod in the channel bottom — over top of hydromulch and erosion control blankets. 11/14/2019 BMP C120: Temporary and Permanent Seeding https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…2/6 Confirm the installation of all required surface water control measures to prevent seed from washing away. Hydroseed applications shall include a minimum of 1,500 pounds per acre of mulch with 3 percent tackifier. See BMP C121: Mulching for specifications. 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. 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. Enhance vegetation establishment by dividing the hydromulch operation into two phases: Phase 1- Install all seed and fertilizer with 25-30 percent mulch and tackifier onto soil in the first lift. Phase 2- Install the rest of the mulch and tackifier over the first lift. Or, enhance vegetation by: Installing the mulch, seed, fertilizer, and tackifier in one lift. Spread or blow straw over the top of the hydromulch at a rate of 800-1000 pounds per acre. 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: Irrigation. Reapplication of mulch. Repair of failed slope surfaces. This technique works with standard hydromulch (1,500 pounds per acre minimum) and Bonded Fiber Matrix/ Mechanically Bonded Fiber Matrix (BFM/MBFMs) (3,000 pounds per acre minimum). Seed may be installed by hand if: Temporary and covered by straw, mulch, or topsoil. Permanent in small areas (usually less than 1 acre) and covered with mulch, topsoil, or erosion blankets. The seed mixes listed in Table II-3.4: Temporary and Permanent Seed Mixes include recommended mixes for both temporary and permanent seeding. 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 11/14/2019 BMP C120: Temporary and Permanent Seeding https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…3/6 rate of 60 pounds per acre. 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. Table II-3.4: Temporary and Permanent Seed Mixes 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 Festuca 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 maintenance. Dwarf tall fescue (several varieties)Festuca arundinacea 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 fescue Festuca arundinacea or Festuca elatior 75-80 98 90 Seaside/Creeping bentgrass Agrostis palustris 10-15 92 85 11/14/2019 BMP C120: Temporary and Permanent Seeding https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…4/6 Common Name Latin Name % Weight % Purity % Germination 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 wetlands. Consult Hydraulic Permit Authority (HPA) for seed mixes if applicable. Tall or meadow fescue Festuca arundinacea or Festuca elatior 60-70 98 90 Seaside/Creeping bentgrass Agrostis palustris 10-15 98 85 Meadow foxtail Alepocurus pratensis 10-15 90 80 Alsike clover Trifolium hybridum 1-6 98 90 Redtop bentgrass Agrostis alba 1-6 92 85 Meadow Seed Mix A recommended meadow seed mix for infrequently maintained areas or non-maintained areas where colonization by native plants is desirable. Likely applications include rural road and utility right-of-way. Seeding should take place in September or very early October in order to obtain adequate establishment prior to the winter months. Consider the appropriateness of clover, a fairly invasive species, in the mix. Amending the soil can reduce the need for clover. Redtop or Oregon bentgrass Agrostis alba or Agrostis oregonensis 20 92 85 Red fescue Festuca rubra 70 98 90 White dutch clover Trifolium repens 10 98 90 Roughening and Rototilling 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. 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, permanent areas shall use soil amendments to achieve organic matter and permeability performance defined in engineered soil/landscape systems. For systems that are deeper than 8 inches complete the rototilling process in multiple lifts, or prepare the engineered soil system per specifications and place to achieve the specified depth. Fertilizers Conducting soil tests to determine the exact type and quantity of fertilizer is recommended. This will prevent the over-application of fertilizer. 11/14/2019 BMP C120: Temporary and Permanent Seeding https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…5/6 Organic matter is the most appropriate form of fertilizer because it provides nutrients (including nitrogen, phosphorus, and potassium) in the least water-soluble form. 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 agitate, more than 20 minutes before use. Too much agitation destroys the slow-release coating. 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 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. Install products per manufacturer's instructions. BFMs and MBFMs provide good alternatives to blankets in most areas requiring vegetation establishment. Advantages over blankets include: BFM and MBFMs do not require surface preparation. Helicopters can assist in installing BFM and MBFMs in remote areas. On slopes steeper than 2.5H:1V, blanket installers may require ropes and harnesses for safety. Installing BFM and MBFMs can save at least $1,000 per acre compared to blankets. 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. Reseed and protect by mulch any areas that experience erosion after achieving adequate cover. Reseed and protect by mulch any eroded area. Supply seeded areas with adequate moisture, but do not water to the extent that it causes runoff. Approved as Functionally Equivalent 11/14/2019 BMP C120: Temporary and Permanent Seeding https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…6/6 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-permittee-guidance- resources/Emerging-stormwater-treatment-technologies Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 11/14/2019 BMP C121: Mulching https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…1/4 You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C121: Mulching 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: For less than 30 days on disturbed areas that require cover. At all times for seeded areas, especially during the wet season and during the hot summer months. 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: cottonseed meal; fibers made of wood, recycled cellulose, hemp, or kenaf; compost; or blends of these. Tackifier shall be plant-based, such as guar or alpha plantago, or chemical-based such as polyacrylamide or polymers. Generally, mulches come in 40-50 pound bags. Seed and fertilizer are added at time of application. Recycled cellulose may contain polychlorinated biphenyl (PCBs). Ecology recommends that products should be evaluated for PCBs prior to use. Refer to BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection for conditions of use. PAM shall not be directly applied to water or allowed to enter a water body. Any mulch or tackifier product used shall be installed per the manufacturer’s instructions. Design and Installation Specifications 11/14/2019 BMP C121: Mulching https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…2/4 For mulch materials, application rates, and specifications, see Table II-3.6: Mulch Standards and Guidelines. Consult with the local supplier or the local conservation district for their recommendations. Increase the application rate until the ground is 95% covered (i.e. not visible under the mulch layer). Note: Thickness may be increased for disturbed areas in or near sensitive areas or other areas highly susceptible to erosion. Where the option of “Compost” is selected, it should be a coarse compost that meets the size gradations listed in Table II-3.5: Size Gradations of Compost as Mulch Material when tested in accordance with Test Method 02.02-B found in Test Methods for the Examination of Composting and Compost (Thompson, 2001). Table II-3.5: Size Gradations of Compost as Mulch Material Sieve Size Percent Passing 3"100% 1"90% - 100% 3/4"70% - 100% 1/4"40% - 100% Mulch used within the ordinary high-water mark of surface waters should be selected to minimize potential flotation of organic matter. Composted organic materials have higher specific gravities (densities) than straw, wood, or chipped material. Consult the Hydraulic Permit Authority (HPA) for mulch mixes if applicable. Maintenance Standards The thickness of the mulch cover must be maintained. Any areas that experience erosion shall be remulched and/or protected with a net or blanket. If the erosion problem is drainage related, then the problem shall be fixed and the eroded area remulched. Table II-3.6: Mulch Standards and Guidelines Mulch Material Guideline Description Straw Quality Standards Air-dried; free from undesirable seed and coarse material. Application Rates 2"-3" thick; 5 bales per 1,000 sf or 2-3 tons per acre 11/14/2019 BMP C121: Mulching https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…3/4 Mulch Material Guideline Description Remarks Cost-effective protection when applied with adequate thickness. Hand-application generally requires greater thickness than blown straw. The thickness of straw may be reduced by half when used in conjunction with seeding. In windy areas straw must be held in place by crimping, using a tackifier, or covering with netting. Blown straw always has to be held in place with a tackifier as even light winds will blow it away. Straw, however, has several deficiencies that should be considered when selecting mulch materials. It often introduces and/or encourages the propagation of weed species and it has no significant long-term benefits It should also not be used within the ordinary high-water elevation of surface waters (due to flotation). Hydromulch Quality Standards No growth inhibiting factors. Application Rates Approx. 35-45 lbs per 1,000 sf or 1,500 - 2,000 lbs per acre Remarks Shall be applied with hydromulcher. Shall not be used without seed and tackifier unless the application rate is at least doubled. Fibers longer than about 3/4 - 1 inch clog hydromulch equipment. Fibers should be kept to less than 3/4 inch. Compost Quality Standards No visible water or dust during handling. Must be produced per WAC 173-350, Solid Waste Handling Standards, but may have up to 35% biosolids. Application Rates 2" thick min.; approx. 100 tons per acre (approx. 750 lbs per cubic yard) Remarks More effective control can be obtained by increasing thickness to 3". Excellent mulch for protecting final grades until landscaping because it can be directly seeded or tilled into soil as an amendment. Compost used for mulch has a coarser size gradation than compost used for BMP C125: Topsoiling / Composting or BMP T5.13: Post-Construction Soil Quality and Depth. It is more stable and practical to use in wet areas and during rainy weather conditions. Do not use near wetlands or near phosphorous impaired water bodies. Chipped Site Vegetation Quality Standards Gradations from fines to 6 inches in length for texture, variation, and interlocking properties. Include a mix of various sizes so that the average size is between 2- and 4- inches. Application Rates 2" thick min.; Remarks This is a cost-effective way to dispose of debris from clearing and grubbing, and it eliminates the problems associated with burning. Generally, it should not be used on slopes above approx. 10% because of its tendency to be transported by runoff. It is not recommended within 200 feet of surface waters. If permanent seeding or planting is expected shortly after mulch, the decomposition of the chipped vegetation may tie up nutrients important to grass establishment. Note: thick application of this material over existing grass, herbaceous species, and some groundcovers could smother and kill vegetation. Wood- Based Mulch Quality Standards No visible water or dust during handling. Must be purchased from a supplier with a Solid Waste Handling Permit or one exempt from solid waste regulations. 11/14/2019 BMP C121: Mulching https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…4/4 Mulch Material Guideline Description Application Rates 2" thick min.; approx. 100 tons per acre (approx. 750 lbs. per cubic yard) Remarks This material is often called "wood straw" or "hog fuel". The use of mulch ultimately improves the organic matter in the soil. Special caution is advised regarding the source and composition of wood-based mulches. Its preparation typically does not provide any weed seed control, so evidence of residual vegetation in its composition or known inclusion of weed plants or seeds should be monitored and prevented (or minimized). Wood Strand Mulch Quality Standards A blend of loose, long, thin wood pieces derived from native conifer or deciduous trees with high length-to-width ratio. Application Rates 2" thick min. Remarks Cost-effective protection when applied with adequate thickness. A minimum of 95-percent of the wood strand shall have lengths between 2 and 10-inches, with a width and thickness between 1/16 and 1/2-inches. The mulch shall not contain resin, tannin, or other compounds in quantities that would be detrimental to plant life. Sawdust or wood shavings shall not be used as mulch. [Specification 9-14.4(4) from the Standard Specifications for Road, Bridge, and Municipal Construction (WSDOT, 2016) Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 4/1/2020 BMP C122: Nets and Blankets https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…1/4 You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C122: Nets and Blankets BMP C122: Nets and Blankets Purpose Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so that vegetation can become well established. In addition, some nets and blankets can be used to permanently reinforce turf to protect drainage ways during high flows. Nets (commonly called matting) are strands of material woven into an open, but high-tensile strength net (for example, coconut fiber matting). Blankets are strands of material that are not tightly woven, but instead form a layer of interlocking fibers, typically held together by a biodegradable or photodegradable netting (for example, excelsior or straw blankets). They generally have lower tensile strength than nets, but cover the ground more completely. Coir (coconut fiber) fabric comes as both nets and blankets. Conditions of Use Erosion control netting and blankets shall be made of natural plant fibers unaltered by synthetic materials. Erosion control nets and blankets should be used: To aid permanent vegetated stabilization of slopes 2H:1V or greater and with more than 10 feet of vertical relief. For drainage ditches and swales (highly recommended). The application of appropriate netting or blanket to drainage ditches and swales can protect bare soil from channelized runoff while vegetation is established. Nets and blankets also can capture a great deal of sediment due to their open, porous structure. Nets and blankets can be used to permanently stabilize channels and may provide a cost-effective, environmentally preferable alternative to riprap. Disadvantages of nets and blankets include: Surface preparation is required. On slopes steeper than 2.5H:1V, net and blanket installers may need to be roped and harnessed for safety. They cost at least $4,000-6,000 per acre installed. Advantages of nets and blankets include: Installation without mobilizing special equipment. Installation by anyone with minimal training Installation in stages or phases as the project progresses. 4/1/2020 BMP C122: Nets and Blankets https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…2/4 Installers can hand place seed and fertilizer as they progress down the slope. Installation in any weather. There are numerous types of nets and blankets that can be designed with various parameters in mind. Those parameters include: fiber blend, mesh strength, longevity, biodegradability, cost, and availability. An alternative to nets and blankets in some limited conditions is BMP C202: Riprap Channel Lining. Ensure that BMP C202: Riprap Channel Lining is appropriate before using it as a substitute for nets and blankets. Design and Installation Specifications See Figure II-3.3: Channel Installation (Clackamas County et al., 2008) and Figure II-3.4: Slope Installation for typical orientation and installation of nets and blankets used in channels and as slope protection. Note: these are typical only; all nets and blankets must be installed per manufacturer’s installation instructions. Installation is critical to the effectiveness of these products. If good ground contact is not achieved, runoff can concentrate under the product, resulting in significant erosion. Installation of nets and blankets on slopes: 1. Complete final grade and track walk up and down the slope. 2. Install hydromulch with seed and fertilizer. 3. Dig a small trench, approximately 12 inches wide by 6 inches deep along the top of the slope. 4. Install the leading edge of the net/blanket into the small trench and staple approximately every 18 inches. NOTE: Staples are metal, “U”-shaped, and a minimum of 6 inches long. Longer staples are used in sandy soils. Biodegradable stakes are also available. 5. Roll the net/blanket slowly down the slope as the installer walks backward. NOTE: The net/blanket rests against the installer’s legs. Staples are installed as the net/blanket is unrolled. It is critical that the proper staple pattern is used for the net/blanket being installed. The net/blanket is not to be allowed to roll down the slope on its own as this stretches the net/blanket, making it impossible to maintain soil contact. In addition, no one is allowed to walk on the net/blanket after it is in place. 6. If the net/blanket is not long enough to cover the entire slope length, the trailing edge of the upper net/blanket should overlap the leading edge of the lower net/blanket and be stapled. On steeper slopes, this overlap should be installed in a small trench, stapled, and covered with soil. With the variety of products available, it is impossible to cover all the details of appropriate use and installation. Therefore, it is critical that the designer consult the manufacturer's information and that a site visit takes place in order to ensure that the product specified is appropriate. Information is also available in WSDOT's Standard Specifications for Road, Bridge, and Municipal Construction Division 8-01 and Division 9-14 (WSDOT, 2016). 4/1/2020 BMP C122: Nets and Blankets https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…3/4 Use jute matting in conjunction with mulch (BMP C121: Mulching). Excelsior, woven straw blankets and coir (coconut fiber) blankets may be installed without mulch. There are many other types of erosion control nets and blankets on the market that may be appropriate in certain circumstances. In general, most nets (e.g., jute matting) require mulch in order to prevent erosion because they have a fairly open structure. Blankets typically do not require mulch because they usually provide complete protection of the surface. Extremely steep, unstable, wet, or rocky slopes are often appropriate candidates for use of synthetic blankets, as are riverbanks, beaches and other high-energy environments. If synthetic blankets are used, the soil should be hydromulched first. 100-percent biodegradable blankets are available for use in sensitive areas. These organic blankets are usually held together with a paper or fiber mesh and stitching which may last up to a year. Most netting used with blankets is photodegradable, meaning it breaks down under sunlight (not UV stabilized). However, this process can take months or years even under bright sun. Once vegetation is established, sunlight does not reach the mesh. It is not uncommon to find non-degraded netting still in place several years after installation. This can be a problem if maintenance requires the use of mowers or ditch cleaning equipment. In addition, birds and small animals can become trapped in the netting. Maintenance Standards Maintain good contact with the ground. Erosion must not occur beneath the net or blanket. Repair and staple any areas of the net or blanket that are damaged or not in close contact with the ground. Fix and protect eroded areas if erosion occurs due to poorly controlled drainage. Figure II-3.3: Channel Installation pdf download Figure II-3.4: Slope Installation pdf download Washington State Department of Ecology 4/1/2020 BMP C122: Nets and Blankets https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…4/4 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 D EPARTMENT OF ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Slope Installation Revised June 2016 NOT TO SCALE Notes: 1. Slope surface shall be smooth before placement for proper soil contact. 2. Stapling pattern as per manufacturer's recommendations. 3. Do not stretch blankets/mattings tight - allow the rolls to mold to any irregularities. 4. For slopes less than 3H:1V, rolls may be placed in horizontal strips. 5. If there is a berm at the top of the slope, anchor upslope of the berm. 6. Lime, fertilize, and seed before installation. Planting of shrubs, trees, etc. should occur after installation. Min. 2" overlap Anchor in 6" x 6" min. trench and staple at 12" intervals Min. 6" overlap Staple overlaps max. 5" spacing Bring material down to a level area, turn the end under 4" and staple at 12" intervals 11/14/2019 BMP C123: Plastic Covering https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…1/3 You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C123: Plastic Covering BMP C123: Plastic Covering Purpose Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas. Conditions of Use Plastic covering may be used on disturbed areas that require cover measures for less than 30 days, except as stated below. Plastic is particularly useful for protecting cut and fill slopes and stockpiles. However, the relatively rapid breakdown of most polyethylene sheeting makes it unsuitable for applications greater than six months. Due to rapid runoff caused by plastic covering, do not use this method upslope of areas that might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes. Plastic sheeting may result in increased runoff volumes and velocities, requiring additional on-site measures to counteract the increases. Creating a trough with wattles or other material can convey clean water away from these areas. To prevent undercutting, trench and backfill rolled plastic covering products. Although the plastic material is inexpensive to purchase, the cost of installation, maintenance, removal, and disposal add to the total costs of this BMP. Whenever plastic is used to protect slopes, install water collection measures at the base of the slope. These measures include plastic-covered berms, channels, and pipes used to convey clean rainwater away from bare soil and disturbed areas. Do not mix clean runoff from a plastic covered slope with dirty runoff from a project. Other uses for plastic include: Temporary ditch liner. Pond liner in temporary sediment pond. Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel being stored. Emergency slope protection during heavy rains. Temporary drainpipe (“elephant trunk”) used to direct water. Design and Installation Specifications 11/14/2019 BMP C123: Plastic Covering https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…2/3 Plastic slope cover must be installed as follows: 1. Run plastic up and down the slope, not across the slope. 2. Plastic may be installed perpendicular to a slope if the slope length is less than 10 feet. 3. Provide a minimum of 8-inch overlap at the seams. 4. On long or wide slopes, or slopes subject to wind, tape all seams. 5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench at the top of the slope and backfill with soil to keep water from flowing underneath. 6. Place sand filled burlap or geotextile bags every 3 to 6 feet along seams and tie them together with twine to hold them in place. 7. Inspect plastic for rips, tears, and open seams regularly and repair immediately. This preventsInsp high velocity runoff from contacting bare soil, which causes extreme erosion. 8. Sandbags may be lowered into place tied to ropes. However, all sandbags must be staked in place. Plastic sheeting shall have a minimum thickness of 0.06 millimeters. If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable protection shall be installed at the toe of the slope in order to reduce the velocity of runoff. Maintenance Standards Torn sheets must be replaced and open seams repaired. Completely remove and replace the plastic if it begins to deteriorate due to ultraviolet radiation. Completely remove plastic when no longer needed. Dispose of old tires used to weight down plastic sheeting appropriately. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did not pass through the Technology Assessment Protocol – Ecology (TAPE) process. Local 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-permittee-guidance- resources/Emerging-stormwater-treatment-technologies Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) 11/14/2019 BMP C123: Plastic Covering https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…3/3 Publication No.19-10-021 12/12/2019 BMP C140: Dust Control https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…1/2 You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C140: Dust Control 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 Vegetate or mulch areas that will not receive vehicle traffic. In areas where planting, mulching, or paving is impractical, apply gravel or landscaping rock. 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. Construct natural or artificial windbreaks or windscreens. These may be designed as enclosures for small dust sources. 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. 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. Spray exposed soil areas with a dust palliative, following the manufacturer’s instructions and cautions regarding handling and application. Used oil is prohibited from use as a dust suppressant. Local governments may approve other dust palliatives such as calcium chloride or PAM. PAM (BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection) added to water at a rate of 0.5 pounds per 1,000 gallons of water per acre and applied from a water truck is more effective than water alone. This is due to increased infiltration of water into the soil and reduced evaporation. In addition, small soil particles are bonded together and are not as easily transported by wind. Adding PAM may reduce the quantity of water needed for dust control. Note that the application rate specified here applies to this BMP, and is not the same application rate that is specified in BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection, but the downstream protections still apply. 12/12/2019 BMP C140: Dust Control https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…2/2 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. Contact your local Air Pollution Control Authority for guidance and training on other dust control measures. Compliance with the local Air Pollution Control Authority constitutes compliance with this BMP. Use vacuum street sweepers. Remove mud and other dirt promptly so it does not dry and then turn into dust. Techniques that can be used for unpaved roads and lots include: Lower speed limits. High vehicle speed increases the amount of dust stirred up from unpaved roads and lots. Upgrade the road surface strength by improving particle size, shape, and mineral types that make up the surface and base materials. 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. Use geotextile fabrics to increase the strength of new roads or roads undergoing reconstruction. Encourage the use of alternate, paved routes, if available. 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. Limit dust-causing work on windy days. Pave unpaved permanent roads and other trafficked areas. Maintenance Standards Respray area as necessary to keep dust to a minimum. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 1/17/2020 BMP C150: Materials on Hand https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…1/2 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C150: Materials on Hand BMP C150: Materials on Hand Purpose Keep quantities of erosion prevention and sediment control materials on the project site at all times to be used for regular maintenance and emergency situations such as unexpected heavy rains. Having these materials on-site reduces the time needed to replace existing or implement new BMPs when inspections indicate that existing BMPs are not meeting the Construction SWPPP requirements. In addition, contractors can save money by buying some materials in bulk and storing them at their office or yard. Conditions of Use 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 pipe, sandbags, geotextile fabric and steel “T” posts. 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. 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: Clear Plastic, 6 mil Drainpipe, 6 or 8 inch diameter Sandbags, filled Straw Bales for mulching Quarry Spalls Washed Gravel 1/17/2020 BMP C150: Materials on Hand https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…2/2 Geotextile Fabric Catch Basin Inserts Steel "T" Posts Silt fence material Straw Wattles Maintenance Standards 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. Re-stock materials as needed. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 1/17/2020 BMP C151: Concrete Handling https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…1/2 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C151: Concrete Handling 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 discharge to waters of the State is prohibited. Use this BMP to minimize and eliminate concrete, concrete process water, and concrete slurry from entering waters of the State. Conditions of Use Any time concrete is used, utilize these management practices. Concrete construction project components include, but are not limited to: Curbs Sidewalks Roads Bridges Foundations Floors 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 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. 1/17/2020 BMP C151: Concrete Handling https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…2/2 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. 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. At no time shall concrete be washed off into the footprint of an area where an infiltration feature will be installed. Wash equipment difficult to move, such as concrete paving machines, in areas that do not directly drain to natural or constructed stormwater conveyance or potential infiltration areas. Do not allow washwater from areas, such as concrete aggregate driveways, to drain directly (without detention or treatment) to natural or constructed stormwater conveyances. 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 contained concrete and concrete washwater (process water) properly. Always use forms or solid barriers for concrete pours, such as pilings, within 15-feet of surface waters. Refer to BMP C252: Treating and Disposing of High pH Water for pH adjustment requirements. Refer to the Construction Stormwater General Permit (CSWGP) for pH monitoring requirements if the project involves one of the following activities: Significant concrete work (as defined in the CSWGP). The use of soils amended with (but not limited to) Portland cement-treated base, cement kiln dust or fly ash. 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. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 12/12/2019 BMP C152: Sawcutting and Surfacing Pollution Prevention https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…1/2 You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C152: Sawcutting and Surfacing Pollution Prevention 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 entering waters of the State. Conditions of Use Utilize these management practices anytime sawcutting or surfacing operations take place. Sawcutting and surfacing operations include, but are not limited to: Sawing Coring Grinding Roughening Hydro-demolition Bridge and road surfacing Design and Installation Specifications Vacuum slurry and cuttings during cutting and surfacing operations. Slurry and cuttings shall not remain on permanent concrete or asphalt pavement overnight. Slurry and cuttings shall not drain to any natural or constructed drainage conveyance including stormwater systems. This may require temporarily blocking catch basins. Dispose of collected slurry and cuttings in a manner that does not violate ground water or surface water quality standards. 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. 12/12/2019 BMP C152: Sawcutting and Surfacing Pollution Prevention https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…2/2 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. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 12/12/2019 BMP C153: Material Delivery, Storage, and Containment https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…1/3 You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C153: Material Delivery, Storage, and Containment 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 materials in a designated area, and install secondary containment. Conditions of Use Use at construction sites with delivery and storage of the following materials: Petroleum products such as fuel, oil and grease Soil stabilizers and binders (e.g., Polyacrylamide) Fertilizers, pesticides and herbicides Detergents Asphalt and concrete compounds Hazardous chemicals such as acids, lime, adhesives, paints, solvents, and curing compounds Any other material that may be detrimental if released to the environment Design and Installation Specifications The temporary storage area should be located away from vehicular traffic, near the construction entrance(s), and away from waterways or storm drains. Safety Data Sheets (SDS) should be supplied for all materials stored. Chemicals should be kept in their original labeled containers. Hazardous material storage on-site should be minimized. Hazardous materials should be handled as infrequently as possible. During the wet weather season (Oct 1 – April 30), consider storing materials in a covered area. Materials should be stored in secondary containments, such as an earthen dike, horse trough, or even a children’s wading pool for non-reactive materials such as detergents, oil, grease, and paints. Small amounts of material may be secondarily contained in “bus boy” trays or concrete mixing trays. 12/12/2019 BMP C153: Material Delivery, Storage, and Containment https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…2/3 Do not store chemicals, drums, or bagged materials directly on the ground. Place these items on a pallet and, when possible, within secondary containment. 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. 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. Temporary secondary containment facilities shall provide for a spill containment volume able to contain 10% of the total enclosed container volume of all containers, or 110% of the capacity of the largest container within its boundary, whichever is greater. Secondary containment facilities shall be impervious to the materials stored therein for a minimum contact time of 72 hours. Sufficient separation should be provided between stored containers to allow for spill cleanup and emergency response access. 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. Keep material storage areas clean, organized and equipped with an ample supply of appropriate spill clean- up material (spill kit). The spill kit should include, at a minimum: 1-Water Resistant Nylon Bag 3-Oil Absorbent Socks 3”x 4’ 2-Oil Absorbent Socks 3”x 10’ 12-Oil Absorbent Pads 17”x19” 1-Pair Splash Resistant Goggles 3-Pair Nitrile Gloves 10-Disposable Bags with Ties Instructions Maintenance Standards 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 12/12/2019 BMP C153: Material Delivery, Storage, and Containment https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…3/3 shall be handled as hazardous waste unless testing determines them to be non-hazardous. Re-stock spill kit materials as needed. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 1/17/2020 BMP C154: Concrete Washout Area https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…1/5 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C154: Concrete Washout Area 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: Concrete is used as a construction material It is not possible to dispose of all concrete wastewater and washout off-site (ready mix plant, etc.). 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 wheelbarrows) may be washed into formed areas awaiting concrete pour. At no time shall concrete be washed off into the footprint of an area where an infiltration feature will be installed. Design and Installation Specifications Implementation Perform washout of concrete truck drums at an approved off-site location or in designated concrete washout areas only. Do not wash out concrete onto non-formed areas, or into storm drains, open ditches, streets, or streams. Wash equipment difficult to move, such as concrete paving machines, in areas that do not directly drain to natural or constructed stormwater conveyance or potential infiltration areas. Do not allow excess concrete to be dumped on-site, except in designated concrete washout areas as allowed above. Concrete washout areas may be prefabricated concrete washout containers, or self-installed structures (above-grade or below-grade). 1/17/2020 BMP C154: Concrete Washout Area https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…2/5 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. 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. Self-installed above-grade structures should only be used if excavation is not practical. 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 Discuss the concrete management techniques described in this BMP with the ready-mix concrete supplier before any deliveries are made. Educate employees and subcontractors on the concrete waste management techniques described in this BMP. Arrange for the contractor’s superintendent or Certified Erosion and Sediment Control Lead (CESCL) to oversee and enforce concrete waste management procedures. A sign should be installed adjacent to each concrete washout area to inform concrete equipment operators to utilize the proper facilities. Contracts Incorporate requirements for concrete waste management into concrete supplier and subcontractor agreements. Location and Placement Locate concrete washout areas at least 50 feet from sensitive areas such as storm drains, open ditches, water bodies, or wetlands. Allow convenient access to the concrete washout area for concrete trucks, preferably near the area where the concrete is being poured. If trucks need to leave a paved area to access the concrete washout area, prevent track-out with a pad of rock or quarry spalls (see BMP C105: Stabilized Construction Access). These areas should be far enough away from other construction traffic to reduce the likelihood of accidental damage and spills. The number of concrete washout areas you install should depend on the expected demand for storage capacity. On large sites with extensive concrete work, concrete washout areas should be placed in multiple locations for ease of use by concrete truck drivers. 1/17/2020 BMP C154: Concrete Washout Area https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…3/5 Concrete Truck Washout Procedures Washout of concrete truck drums shall be performed in designated concrete washout areas only. 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 Concrete washout areas should be constructed as shown in the figures below, with a recommended 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. 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. Lath and flagging should be commercial type. Liner seams shall be installed in accordance with manufacturers’ recommendations. 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 Inspect and verify that concrete washout areas are in place prior to the commencement of concrete work. Once concrete wastes are washed into the designated washout area and allowed to harden, the concrete should be broken up, removed, and disposed of per applicable solid waste regulations. Dispose of hardened concrete on a regular basis. During periods of concrete work, inspect the concrete washout areas daily to verify continued performance. Check overall condition and performance. Check remaining capacity (% full). If using self-installed concrete washout areas, verify plastic liners are intact and sidewalls are not damaged. If using prefabricated containers, check for leaks. Maintain the concrete washout areas to provide adequate holding capacity with a minimum freeboard of 12 inches. 1/17/2020 BMP C154: Concrete Washout Area https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…4/5 Concrete washout areas must be cleaned, or new concrete washout areas must be constructed and ready for use once the concrete washout area is 75% full. If the concrete washout area is nearing capacity, vacuum and dispose of the waste material in an approved manner. Do not discharge liquid or slurry to waterways, storm drains or directly onto ground. Do not discharge to the sanitary sewer without local approval. Place a secure, non-collapsing, non-water collecting cover over the concrete washout area prior to predicted wet weather to prevent accumulation and overflow of precipitation. Remove and dispose of hardened concrete and return the structure to a functional condition. Concrete may be reused on-site or hauled away for disposal or recycling. When you remove materials from a self-installed concrete washout area, build a new structure; 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 When concrete washout areas are no longer required for the work, the hardened concrete, slurries and liquids shall be removed and properly disposed of. Materials used to construct concrete washout areas shall be removed from the site of the work and disposed of or recycled. Holes, depressions or other ground disturbance caused by the removal of the concrete washout areas shall be backfilled, repaired, and stabilized to prevent erosion. Figure II-3.7: Concrete Washout Area with Wood Planks pdf download Figure II-3.8: Concrete Washout Area with Straw Bales pdf download 1/17/2020 BMP C154: Concrete Washout Area https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…5/5 Figure II-3.9: Prefabricated Concrete Washout Container w/Ramp pdf download Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 D EPARTMENT OF ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Concrete Washout Area with Wood Planks Revised June 2016 NOT TO SCALE Sandbag Berm 10 mil plastic lining 1 m Section A-A Plan Type "Below Grade" Lath and flagging on 3 sides 3m Minimum Varies Sandbag Berm 10 mil plastic lining Type "Above Grade" with Wood Planks Section B-B Plan 3m Minimum Stake (typ.) AA 10 mil plastic lining Varies Two-stacked 2x12 rough wood frame BB 10 mil plastic lining Wood frame securely fastened around entire perimeter with two stakes Notes: 1. Actual layout determined in the field. 2. A concrete washout sign shall be installed within 10 m of the temporary concrete washout facility. D EPARTMENT OF ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Concrete Washout Area with Straw Bales Revised June 2016 NOT TO SCALE Type "Above Grade" with Straw Bales Plan Section B-B Concrete Washout Sign Detail (or equivalent) Staple Detail Wood or metal stakes (2 per bale) Staples (2 per bale) Straw bale 10 mil plastic lining Native material (optional) Binding wire CONCRETE WASHOUT 915 mm 915 mm Plywood 1200 mm x 610 mm painted white Black letters 150 mm height Lag screws (12.5 mm) Wood post (89 mm x 89 mm x 2.4 m) 50 mm 200 mm 3.05 mm dia. steel wire 3m Minimum Varies 10 mil plastic lining Stake (typ) Straw bale (typ.) BB Notes: 1. Actual layout determined in the field. 2. The concrete washout sign shall be installed within 10 m of the temporary concrete washout facility. D EPARTMENT OF ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Prefabricated Concrete Washout Container w/Ramp Revised June 2016 NOT TO SCALE 1/17/2020 BMP C160: Certified Erosion and Sediment Control Lead https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…1/2 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C160: Certified Erosion and Sediment Control Lead BMP C160: Certified Erosion and Sediment Control Lead Purpose The project proponent designates at least one person as the responsible representative in charge of erosion and sediment control (ESC), and water quality protection. The designated person shall be responsible for ensuring compliance with all local, state, and federal erosion and sediment control and water quality requirements. Construction sites one acre or larger that discharge to waters of the State must designate a Certified Erosion and Sediment Control Lead (CESCL) as the responsible representative. Conditions of Use A CESCL shall be made available on projects one acre or larger that discharge stormwater to surface waters of the state. Sites less than one acre may have a person without CESCL certification conduct inspections. The CESCL shall: Have a current certificate proving attendance in an erosion and sediment control training course that meets the minimum ESC training and certification requirements established by Ecology. Ecology has provided the minimum requirements for CESCL course training, as well as a list of ESC training and certification providers at: https://ecology.wa.gov/Regulations-Permits/Permits-certifications/Certified-erosion-sediment-control OR Be a Certified Professional in Erosion and Sediment Control (CPESC). For additional information go to: http://www.envirocertintl.org/cpesc/ Specifications CESCL certification shall remain valid for three years. The CESCL shall have authority to act on behalf of the contractor or project proponent and shall be available, or on-call, 24 hours per day throughout the period of construction. The Construction SWPPP shall include the name, telephone number, fax number, and address of the designated CESCL. See II-2 Construction Stormwater Pollution Prevention Plans (Construction SWPPPs). 1/17/2020 BMP C160: Certified Erosion and Sediment Control Lead https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…2/2 A CESCL may provide inspection and compliance services for multiple construction projects in the same geographic region, but must be on site whenever earthwork activities are occurring that could generate release of turbid water. Duties and responsibilities of the CESCL shall include, but are not limited to the following: Maintaining a permit file on site at all times which includes the Construction SWPPP and any associated permits and plans. Directing BMP installation, inspection, maintenance, modification, and removal. Updating all project drawings and the Construction SWPPP with changes made. Completing any sampling requirements including reporting results using electronic Discharge Monitoring Reports (WebDMR). Facilitate, participate in, and take corrective actions resulting from inspections performed by outside agencies or the owner. Keeping daily logs, and inspection reports. Inspection reports should include: Inspection date/time. Weather information; general conditions during inspection and approximate amount of precipitation since the last inspection. Visual monitoring results, including a description of discharged stormwater. The presence of suspended sediment, turbid water, discoloration, and oil sheen shall be noted, as applicable. Any water quality monitoring performed during inspection. General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. A summary or list of all BMPs implemented, including observations of all erosion/sediment control structures or practices. The following shall be noted: 1. Locations of BMPs inspected. 2. Locations of BMPs that need maintenance. 3. Locations of BMPs that failed to operate as designed or intended. 4. Locations of where additional or different BMPs are required. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 1/17/2020 BMP C162: Scheduling https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionSourceCon…1/1 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C162: Scheduling BMP C162: Scheduling Purpose Sequencing a construction project reduces the amount and duration of soil exposed to erosion by wind, rain, runoff, and vehicle tracking. Conditions of Use The construction sequence schedule is an orderly listing of all major land-disturbing activities together with the necessary erosion and sedimentation control measures planned for the project. This type of schedule guides the contractor on work to be done before other work is started so that serious erosion and sedimentation problems can be avoided. Following a specified work schedule that coordinates the timing of land-disturbing activities and the installation of control measures is perhaps the most cost-effective way of controlling erosion during construction. The removal of ground cover leaves a site vulnerable to erosion. Construction sequencing that limits land clearing, provides timely installation of erosion and sedimentation controls, and restores protective cover quickly can significantly reduce the erosion potential of a site. Design Considerations Minimize construction during rainy periods. Schedule projects to disturb only small portions of the site at any one time. Complete grading as soon as possible. Immediately stabilize the disturbed portion before grading the next portion. Practice staged seeding in order to revegetate cut and fill slopes as the work progresses. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 12/12/2019 BMP C220: Inlet Protection https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…1/6 You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C220: Inlet Protection BMP C220: Inlet Protection Purpose Inlet protection prevents coarse sediment from entering drainage systems prior to permanent stabilization 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 drainage areas for an individual inlet to one acre or less. If possible, provide emergency overflows with additional end-of-pipe treatment where stormwater ponding would cause a hazard. Table II-3.10: Storm Drain Inlet Protection Type of Inlet Protection Emergency Overflow Applicable for Paved/ Earthen Surfaces Conditions of Use Drop Inlet Protection Excavated drop inlet protection Yes, temporary flooding may occur Earthen Applicable for heavy flows. Easy to maintain. Large area requirement: 30'x30'/acre Block and gravel drop inlet protection Yes Paved or Earthen Applicable for heavy concentrated flows. Will not pond. Gravel and wire drop inlet protection 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 12/12/2019 BMP C220: Inlet Protection https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…2/6 Type of Inlet Protection Emergency Overflow Applicable for Paved/ Earthen Surfaces Conditions of Use Curb inlet protection with wooden weir Small capacity overflow Paved Used for sturdy, more compact installation. Block and gravel curb inlet protection Yes Paved Sturdy, but limited filtration. Culvert Inlet Protection Culvert inlet sediment trap N/A N/A 18 month expected life. 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 specifications for excavated drop inlet protection include: Provide a depth of 1-2 ft as measured from the crest of the inlet structure. Slope sides of excavation should be no steeper than 2H:1V. Minimum volume of excavation is 35 cubic yards. Shape the excavation to fit the site, with the longest dimension oriented toward the longest inflow area. Install provisions for draining to prevent standing water. Clear the area of all debris. Grade the approach to the inlet uniformly. Drill weep holes into the side of the inlet. Protect weep holes with screen wire and washed aggregate. Seal weep holes when removing structure and stabilizing area. 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 filters include: 12/12/2019 BMP C220: Inlet Protection https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…3/6 Provide a height of 1 to 2 feet above the inlet. Recess the first row of blocks 2-inches into the ground for stability. Support subsequent courses by placing a pressure treated wood 2x4 through the block opening. Do not use mortar. Lay some blocks in the bottom row on their side to allow for dewatering the pool. Place hardware cloth or comparable wire mesh with ½-inch openings over all block openings. Place gravel to just below the top of blocks on slopes of 2H:1V or flatter. An alternative design is a gravel berm surrounding the inlet, as follows: Provide a slope of 3H:1V on the upstream side of the berm. Provide a slope of 2H:1V on the downstream side of the berm. Provide a 1-foot wide level stone area between the gravel berm and the inlet. Use stones 3 inches in diameter or larger on the upstream slope of the berm. Use gravel ½- to ¾-inch at a minimum thickness of 1-foot on the downstream slope of the berm. Figure II-3.17: Block and Gravel Filter pdf download 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: Use a hardware cloth or comparable wire mesh with ½-inch openings. Place wire mesh over the drop inlet so that the wire extends a minimum of 1-foot beyond each side of the inlet structure. Overlap the strips if more than one strip of mesh is necessary. Place coarse aggregate over the wire mesh. Provide at least a 12-inch depth of aggregate over the entire inlet opening and extend at least 18- inches on all sides. 12/12/2019 BMP C220: Inlet Protection https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…4/6 Catch Basin Filters Catch basin filters are designed by manufacturers for construction sites. The limited sediment storage capacity increases the amount of inspection and maintenance required, which may be daily for heavy sediment loads. To reduce maintenance requirements, combine a catch basin filter with another type of inlet protection. This type of inlet protection provides flow bypass without overflow and therefore may be a better method for inlets located along active rights-of-way. Design and installation specifications for catch basin filters include: Provides 5 cubic feet of storage. Requires dewatering provisions. Provides a high-flow bypass that will not clog under normal use at a construction site. 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: Use wire mesh with ½-inch openings. Use extra strength filter cloth. Construct a frame. Attach the wire and filter fabric to the frame. Pile coarse washed aggregate against the wire and fabric. Place weight on the frame anchors. 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 specifications for block and gravel curb inlet protection include: Use wire mesh with ½-inch openings. Place two concrete blocks on their sides abutting the curb at either side of the inlet opening. These are spacer blocks. Place a 2x4 stud through the outer holes of each spacer block to align the front blocks. Place blocks on their sides across the front of the inlet and abutting the spacer blocks. 12/12/2019 BMP C220: Inlet Protection https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…5/6 Place wire mesh over the outside vertical face. Pile coarse aggregate against the wire to the top of the barrier. Figure II-3.18: Block and Gravel Curb Inlet Protection pdf download 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: 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. 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. Figure II-3.19: Curb and Gutter Barrier pdf download Maintenance Standards 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. 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 12/12/2019 BMP C220: Inlet Protection https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…6/6 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-permittee-guidance- resources/Emerging-stormwater-treatment-technologies Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 D EPARTMENT OF ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Block and Gravel Curb Inlet Protection Revised June 2016 NOT TO SCALE Plan View A A Section A-A Notes: 1. Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment, where water can pond and allow sediment to separate from runoff. 2. Barrier shall allow for overflow from severe storm event. 3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately. Back of sidewalk Catch basin Back of curb Curb inlet Concrete block 2x4 Wood stud Concrete block34 inch (20 mm) Drain gravel Wire screen or filter fabric 34 inch (20 mm) Drain gravel Wire screen or filter fabric Ponding height Overflow 2x4 Wood stud (100x50 Timber stud) Concrete block Curb inlet Catch basin D EPARTMENT OF ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Curb and Gutter Barrier Revised June 2016 NOT TO SCALE Plan View Back of sidewalk Runoff Runoff Spillway Burlap sacks to overlap onto curb Gravel filled sandbags stacked tightly Curb inlet Catch basin Back of curb Notes: 1. Place curb type sediment barriers on gently sloping street segments, where water can pond and allow sediment to separate from runoff. 2. Sandbags of either burlap or woven 'geotextile' fabric, are filled with gravel, layered and packed tightly. 3. Leave a one sandbag gap in the top row to provide a spillway for overflow. 4. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately. 1/17/2020 BMP C233: Silt Fence https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionRunoffBM…1/5 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C233: Silt Fence 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. 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. 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. 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. Figure II-3.22: Silt Fence pdf download Design and Installation Specifications Use in combination with other construction stormwater BMPs. Maximum slope steepness (perpendicular to the silt fence line) 1H:1V. Maximum sheet or overland flow path length to the silt fence of 100 feet. Do not allow flows greater than 0.5 cfs. 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 1/17/2020 BMP C233: Silt Fence https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionRunoffBM…2/5 Table II-3.11: Geotextile Fabric Standards for Silt Fence): 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 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. 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. 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. Refer to Figure II-3.22: Silt Fence for standard silt fence details. Include the following Standard 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. 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 1/17/2020 BMP C233: Silt Fence https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionRunoffBM…3/5 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 prevent overturning of the fence due to sediment loading. 10. Use wood, steel or equivalent posts. The spacing of the support posts shall be a maximum of 6-feet. Posts shall consist of either: 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. No. 6 steel rebar or larger. ASTM A 120 steel pipe with a minimum diameter of 1-inch. U, T, L, or C shape steel posts with a minimum weight of 1.35 lbs./ft. Other steel posts having equivalent strength and bending resistance to the post sizes listed above. 11. Locate silt fences on contour as much as possible, except at the ends of the fence, where the fence shall be turned uphill such that the silt fence captures the runoff water and prevents water from flowing around the end of the fence. 1/17/2020 BMP C233: Silt Fence https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionRunoffBM…4/5 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. 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. 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. 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 geotextile 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. Figure II-3.23: Silt Fence Installation by Slicing Method 1/17/2020 BMP C233: Silt Fence https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionRunoffBM…5/5 pdf download Maintenance Standards Repair any damage immediately. Intercept and convey all evident concentrated flows uphill of the silt fence to a sediment trapping BMP. 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. Remove sediment deposits when the deposit reaches approximately one-third the height of the silt fence, or install a second silt fence. Replace geotextile fabric that has deteriorated due to ultraviolet breakdown. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 D EPARTMENT OF ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Silt Fence Revised July 2017 NOT TO SCALE Joints in geotextile fabric shall be spliced at posts. Use staples, wire rings or equivalent to attach fabric to posts 6' max Post spacing may be increased to 8' if wire backing is used 2"x2" by 14 Ga. wire or equivalent, if standard strength fabric used Minimum 4"x4" trench 2"x2" wood posts, steel fence posts, or equivalent 12" min 2' min 2"x2" by 14 Ga. wire or equivalent, if standard strength fabric used Geotextile fabric Minimum 4"x4" trench 2"x2" wood posts, steel fence posts, or equivalent Backfill trench with native soil or 34" - 1.5" washed gravel D EPARTMENT OF ECOLOGY State of Washington Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. Silt Fence Installation by Slicing Method Revised June 2016 NOT TO SCALE Completed Installation Silt Fence Post installed after compaction Vibratory plow is not acceptable because of horizontal compaction Slicing blade (18 mm width) Horizontal chisel point (76 mm width) Fabric above ground 200 - 300mm Roll of silt fenceOperation No more than 24" of a 36" fabric is allowed above groundSteel support post100% compaction 100% compaction FLOW Drive over each side of silt fence 2 to 4 times with device exerting 60 p.s.i. or greater Attach fabric to upstream side of post Ponding height max. 24" POST SPACING: 7' max. on open runs 4' max. on pooling areas POST DEPTH: As much below ground as fabric above ground Top of Fabric Belt top 8" Diagonal attachment doubles strength Attachment Details: x Gather fabric at posts, if needed. x Utilize three ties per post, all within top 8" of fabric. x Position each tie diagonally, puncturing holes vertically a minimum of 1" apart. x Hang each tie on a post nipple and tighten securely. Use cable ties (50 lbs) or soft wire. 1/17/2020 BMP C240: Sediment Trap https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionRunoffBM…1/3 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C240: Sediment Trap BMP C240: Sediment Trap Purpose A sediment trap is a small temporary ponding area with a gravel outlet used to collect and store sediment from sites during construction. Sediment traps, along with other perimeter controls, shall be installed before any land disturbance takes place in the drainage area. Conditions of Use Sediment traps are intended for use on sites where the tributary drainage area is less than 3 acres, with no unusual drainage features, and a projected build-out time of six months or less. The sediment trap is a temporary measure (with a design life of approximately 6 months) and shall be maintained until the tributary area is permanently protected against erosion by vegetation and/or structures. Sediment traps are only effective in removing sediment down to about the medium silt size fraction. Runoff with sediment of finer grades (fine silt and clay) will pass through untreated, emphasizing the need to control erosion to the maximum extent first. Projects that are constructing permanent Flow Control BMPs, or Runoff Treatment BMPs that use ponding for treatment, may use the rough-graded or final-graded permanent BMP footprint for the temporary sediment trap. When permanent BMP footprints are used as temporary sediment traps, the surface area requirement of the sediment trap must be met. If the surface area requirement of the sediment trap is larger than the surface area of the permanent BMP, then the sediment trap shall be enlarged beyond the permanent BMP footprint to comply with the surface area requirement. A floating pond skimmer may be used for the sediment trap outlet if approved by the Local Permitting Authority. Sediment traps may not be feasible on utility projects due to the limited work space or the short-term nature of the work. Portable tanks may be used in place of sediment traps for utility projects. Design and Installation Specifications See Figure II-3.26: Cross Section of Sediment Trap and Figure II-3.27: Sediment Trap Outlet for details. To determine the sediment trap geometry, first calculate the design surface area (SA) of the trap, measured at the invert of the weir. Use the following equation: SA = FS(Q2/Vs) 1/17/2020 BMP C240: Sediment Trap https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionRunoffBM…2/3 where Q2 = Option 1 - Single Event Hydrograph Method: Q2 = Peak volumetric flow rate calculated using a 10-minute time step from a Type 1A, 2-year, 24- hour frequency storm for the developed condition. The 10-year peak volumetric flow rate shall be used if the project size, expected timing and duration of construction, or downstream conditions warrant a higher level of protection. Option 2 - For construction sites that are less than 1 acre, the Rational Method may be used to determine Q2. Vs = The settling velocity of the soil particle of interest. The 0.02 mm (medium silt) particle with an assumed density of 2.65 g/cm3 has been selected as the particle of interest and has a settling velocity (Vs) of 0.00096 ft/sec. FS = A safety factor of 2 to account for non-ideal settling. Therefore, the equation for computing sediment trap surface area becomes: SA = 2 x Q2/0.00096 or 2080 square feet per cfs of inflow Sediment trap depth shall be 3.5 feet minimum from the bottom of the trap to the top of the overflow weir. To aid in determining sediment depth, all sediment traps shall have a staff gauge with a prominent mark 1- foot above the bottom of the trap. Design the discharge from the sediment trap by using the guidance for discharge from temporary sediment ponds in BMP C241: Sediment Pond (Temporary). Maintenance Standards Sediment shall be removed from the trap when it reaches 1-foot in depth. Any damage to the trap embankments or slopes shall be repaired. Figure II-3.26: Cross Section of Sediment Trap 1/17/2020 BMP C240: Sediment Trap https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionRunoffBM…3/3 pdf download Figure II-3.27: Sediment Trap Outlet pdf download Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 12/12/2019 BMP C251: Construction Stormwater Filtration https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…1/3 You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C251: Construction Stormwater Filtration BMP C251: Construction Stormwater Filtration Purpose Filtration removes sediment from runoff originating from disturbed areas of the site. Conditions of Use Traditional Construction Stormwater BMPs used to control soil erosion and sediment loss from construction sites may not be adequate to ensure compliance with the water quality standard for turbidity in the receiving water. Filtration may be used in conjunction with gravity settling to remove sediment as small as fine silt (0.5 µm). The reduction in turbidity will be dependent on the particle size distribution of the sediment in the stormwater. In some circumstances, sedimentation and filtration may achieve compliance with the water quality standard for turbidity. The use of construction stormwater filtration does not require approval from Ecology as long as treatment chemicals are not used. Filtration in conjunction with BMP C250: Construction Stormwater Chemical Treatment requires testing under the Chemical Technology Assessment Protocol – Ecology (CTAPE) before it can be initiated. Approval from Ecology must be obtained at each site where chemical use is proposed prior to use. See https://fortress.wa.gov/ecy/publications/SummaryPages/ecy070258.html for a copy of the Request for Chemical Treatment form. Design and Installation Specifications Two types of filtration systems may be applied to construction stormwater treatment: rapid and slow. Rapid filtration systems are the typical system used for water and wastewater treatment. They can achieve relatively high hydraulic flow rates, on the order of 2 to 20 gpm/sf, because they have automatic backwash systems to remove accumulated solids. Slow filtration systems have very low hydraulic rates, on the order of 0.02 gpm/sf, because they do not have backwash systems. Slow filtration systems have generally been used as post construction BMPs to treat stormwater (see V-6 Filtration BMPs). Slow filtration is mechanically simple in comparison to rapid filtration, but requires a much larger filter area. Filter Types and Efficiencies Sand media filters are available with automatic backwashing features that can filter to 50 µm particle size. Screen or bag filters can filter down to 5 µm. Fiber wound filters can remove particles down to 0.5 µm. Filters should be sequenced from the largest to the smallest pore opening. Sediment removal efficiency will be related to particle size distribution in the stormwater. 12/12/2019 BMP C251: Construction Stormwater Filtration https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…2/3 Treatment Process and Description Stormwater is collected at interception point(s) on the site and diverted to an untreated stormwater sediment pond or tank for removal of large sediment, and storage of the stormwater before it is treated by the filtration system. In a rapid filtration system, the untreated stormwater is pumped from the pond or tank through the filtration media. Slow filtration systems are designed using gravity to convey water from the pond or tank to and through the filtration media. Sizing Filtration treatment systems must be designed to control the velocity and peak volumetric flow rate that is discharged from the system and consequently the project site. See Element 3: Control Flow Rates for further details on this requirement. The untreated stormwater storage pond or tank should be sized to hold 1.5 times the volume of runoff generated from the site during the 10-year, 24-hour storm event, minus the filtration treatment system flowrate for an 8-hour period. For a chitosan-enhanced sand filtration system, the filtration treatment system flowrate should be sized using a hydraulic loading rate between 6-8 gpm/ft2. Other hydraulic loading rates may be more appropriate for other systems. Bypass should be provided around the filtration treatment system to accommodate extreme storm events. Runoff volume shall be calculated using the methods presented in III-2.3 Single Event Hydrograph Method. Worst-case land cover conditions (i.e., producing the most runoff) should be used for analyses (in most cases, this would be the land cover conditions just prior to final landscaping). If the filtration treatment system design does not allow you to discharge at the rates as required by Element 3: Control Flow Rates, and if the site has a permanent Flow Control BMP that will serve the planned development, the discharge from the filtration treatment system may be directed to the permanent Flow Control BMP to comply with Element 3: Control Flow Rates. In this case, all discharge (including water passing through the treatment system and stormwater bypassing the treatment 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 permanent 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 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 treatment and disposal may be necessary. Screen, bag, and fiber filters must be cleaned and/or replaced when they become clogged. 12/12/2019 BMP C251: Construction Stormwater Filtration https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeII/ConstructionStormwaterBMPs/Constructi…3/3 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. Disposal of filtration equipment must comply with applicable local, state, and federal regulations. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 1/17/2020 BMP C252: Treating and Disposing of High pH Water https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionRunoffBM…1/4 Open topic with navigation You are here: 2019 SWMMWW > Volume II - Construction Stormwater Pollution Prevention > II-3 Construction Stormwater BMPs > BMP C252: Treating and Disposing of High pH Water 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 typical 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 The water quality standard for pH in Washington State is in the range of 6.5 to 8.5. Stormwater 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. Neutralized stormwater may be discharged to surface waters under the Construction Stormwater General permit. 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 contaminated during concrete work is considered process wastewater and must not be discharged to waters of the State or stormwater collection systems. 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 procedures). 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 standard for calcium and other dissolved solids in Washington State is less than 500 mg/l. Treating High pH Stormwater by Carbon Dioxide Sparging 1/17/2020 BMP C252: Treating and Disposing of High pH Water https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionRunoffBM…2/4 Advantages of Carbon Dioxide Sparging Rapidly neutralizes high pH water. Cost effective and safer to handle than acid compounds. CO2 is self-buffering. It is difficult to overdose and create harmfully low pH levels. Material is readily available. The Chemical Process of Carbon Dioxide Sparging When carbon dioxide (CO2) is added to water (H2O), carbonic acid (H2CO3) is formed which can further dissociate into a proton (H+) and a bicarbonate anion (HCO3-) as shown below: CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3- The free proton is a weak acid that can lower the pH. Water temperature has an effect on the reaction 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 training on their devices. The following procedure may be used when not using a continuous discharge system: 1. Prior to treatment, the appropriate jurisdiction should be notified in accordance with the regulations 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 treatment 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 1/17/2020 BMP C252: Treating and Disposing of High pH Water https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionRunoffBM…3/4 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). 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 Only permitted facilities may accept high pH water. Contact the facility to ensure they can accept the high pH water. Maintenance Standards 1/17/2020 BMP C252: Treating and Disposing of High pH Water https://fortress.wa.gov/ecy/ezshare/wq/Permits/Flare/2019SWMMWW/Content/Topics/VolumeII/ConstructionStormwaterBMPs/ConstructionRunoffBM…4/4 Safety and materials handling: All equipment should be handled in accordance with OSHA rules and regulations. Follow manufacturer guidelines for materials handling. Each operator should provide: A diagram of the monitoring and treatment equipment. A description of the pumping rates and capacity the treatment equipment is capable of treating. Each operator should keep a written record of the following: Client name and phone number. Date of treatment. Weather conditions. Project name and location. Volume of water treated. pH of untreated water. Amount of CO2 or food grade vinegar needed to adjust water to a pH range of 6.9-7.1. pH of treated water. 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. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 Appendix C – Site Inspection Form Construction Stormwater Site Inspection Form Page 1 Project Name Cherie Lane Permit # Inspection Date Time Name of Certified Erosion Sediment Control Lead (CESCL) or qualified inspector if less than one acre Print Name: Approximate rainfall amount since the last inspection (in inches): Approximate rainfall amount in the last 24 hours (in inches): Current Weather Clear Cloudy Mist Rain Wind Fog A. Type of inspection: Weekly Post Storm Event Other B. Phase of Active Construction (check all that apply): Pre Construction/installation of erosion/sediment controls Clearing/Demo/Grading Infrastructure/storm/roads Concrete pours Vertical Construction/buildings Utilities Offsite improvements Site temporary stabilized Final stabilization C. Questions: 1. Were all areas of construction and discharge points inspected? Yes No 2. Did you observe the presence of suspended sediment, turbidity, discoloration, or oil sheen Yes No 3. Was a water quality sample taken during inspection? (refer to permit conditions S4 & S5) Yes No 4. Was there a turbid discharge 250 NTU or greater, or Transparency 6 cm or less?* Yes No 5. If yes to #4 was it reported to Ecology? Yes No 6. Is pH sampling required? pH range required is 6.5 to 8.5. Yes No If answering yes to a discharge, describe the event. Include when, where, and why it happened; what action was taken, and when. *If answering yes to # 4 record NTU/Transparency with continual sampling daily until turbidity is 25 NTU or less/ transparency is 33 cm or greater. Sampling Results: Date: Parameter Method (circle one) Result Other/Note NTU cm pH Turbidity tube, meter, laboratory pH Paper, kit, meter Construction Stormwater Site Inspection Form Page 2 D. Check the observed status of all items. Provide “Action Required “details and dates. Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 1 Clearing Limits Before beginning land disturbing activities are all clearing limits, natural resource areas (streams, wetlands, buffers, trees) protected with barriers or similar BMPs? (high visibility recommended) 2 Construction Access Construction access is stabilized with quarry spalls or equivalent BMP to prevent sediment from being tracked onto roads? Sediment tracked onto the road way was cleaned thoroughly at the end of the day or more frequent as necessary. 3 Control Flow Rates Are flow control measures installed to control stormwater volumes and velocity during construction and do they protect downstream properties and waterways from erosion? If permanent infiltration ponds are used for flow control during construction, are they protected from siltation? 4 Sediment Controls All perimeter sediment controls (e.g. silt fence, wattles, compost socks, berms, etc.) installed, and maintained in accordance with the Stormwater Pollution Prevention Plan (SWPPP). Sediment control BMPs (sediment ponds, traps, filters etc.) have been constructed and functional as the first step of grading. Stormwater runoff from disturbed areas is directed to sediment removal BMP. 5 Stabilize Soils Have exposed un-worked soils been stabilized with effective BMP to prevent erosion and sediment deposition? Construction Stormwater Site Inspection Form Page 3 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 5 Stabilize Soils Cont. Are stockpiles stabilized from erosion, protected with sediment trapping measures and located away from drain inlet, waterways, and drainage channels? Have soils been stabilized at the end of the shift, before a holiday or weekend if needed based on the weather forecast? 6 Protect Slopes Has stormwater and ground water been diverted away from slopes and disturbed areas with interceptor dikes, pipes and or swales? Is off-site storm water managed separately from stormwater generated on the site? Is excavated material placed on uphill side of trenches consistent with safety and space considerations? Have check dams been placed at regular intervals within constructed channels that are cut down a slope? 7 Drain Inlets Storm drain inlets made operable during construction are protected. Are existing storm drains within the influence of the project protected? 8 Stabilize Channel and Outlets Have all on-site conveyance channels been designed, constructed and stabilized to prevent erosion from expected peak flows? Is stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes and downstream conveyance systems? 9 Control Pollutants Are waste materials and demolition debris handled and disposed of to prevent contamination of stormwater? Has cover been provided for all chemicals, liquid products, petroleum products, and other material? Has secondary containment been provided capable of containing 110% of the volume? Were contaminated surfaces cleaned immediately after a spill incident? Were BMPs used to prevent contamination of stormwater by a pH modifying sources? Construction Stormwater Site Inspection Form Page 4 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 9 Cont. Wheel wash wastewater is handled and disposed of properly. 10 Control Dewatering Concrete washout in designated areas. No washout or excess concrete on the ground. Dewatering has been done to an approved source and in compliance with the SWPPP. Were there any clean non turbid dewatering discharges? 11 Maintain BMP Are all temporary and permanent erosion and sediment control BMPs maintained to perform as intended? 12 Manage the Project Has the project been phased to the maximum degree practicable? Has regular inspection, monitoring and maintenance been performed as required by the permit? Has the SWPPP been updated, implemented and records maintained? 13 Protect LID Is all Bioretention and Rain Garden Facilities protected from sedimentation with appropriate BMPs? Is the Bioretention and Rain Garden protected against over compaction of construction equipment and foot traffic to retain its infiltration capabilities? Permeable pavements are clean and free of sediment and sediment laden- water runoff. Muddy construction equipment has not been on the base material or pavement. Have soiled permeable pavements been cleaned of sediments and pass infiltration test as required by stormwater manual methodology? Heavy equipment has been kept off existing soils under LID facilities to retain infiltration rate. E. Check all areas that have been inspected. All in place BMPs All disturbed soils All concrete wash out area All material storage areas All discharge locations All equipment storage areas All construction entrances/exits Construction Stormwater Site Inspection Form Page 5 F. Elements checked “Action Required” (section D) describe corrective action to be taken. List the element number; be specific on location and work needed. Document, initial, and date when the corrective action has been completed and inspected. Element # Description and Location Action Required Completion Date Initials Attach additional page if needed Sign the following certification: “I certify that this report is true, accurate, and complete, to the best of my knowledge and belief” Inspected by: (print) (Signature) Date: Title/Qualification of Inspector: Appendix D – Sediment Tank/Pump Design Calculations Sediment Tank Geometry Calculations To determine the sediment tank geometry, the design volume of the tank was calculated using the equation below: SA = 2080*D*Q2 Q2 = Peak volumetric flow rate calculated using a 10-minute time step from the 2-year, 24-hour frequency storm for the developed condition. D = Minimum Depth of 3.5’ In the fully developed condition was modeled using WWHM. Based on the output provided in the table below, Q2 for the developed condition is 0.1033 CFS. Using the formula above, the minimum design volume for the 2-year flow is: SA = 2080*3.5*0.1033 = 752 CF = 5625 Gal Based on this calculation, the contractor should install a minimum 5625-Gal sediment tank in the location indicated on the TESC Plan. Stormwater runoff from the site will be pumped up to the proposed sediment tank location via a sump pump capable of pumping 83 GPM @ 50 feet of head (see pump calculation below). A gravity overflow will be provided from the sediment tank to the existing stormwater system in the utility easement. Pump Sizing Calculations The sump pump has been sized for the 10-year developed flow of 0.1837 CFS. 0.1837 CFS * 448.83 = 83 GPM