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HomeMy WebLinkAboutSWPPP - HeatherDowns - stamped1 Construction Stormwater Pollution Prevention (CSWPPP) Prepared for: City of Renton Public Works Department Heather Downs Detention Pond Water Quality Retrofit Project Prepared by: Ken Srilofung, PE Civil Engineer 3-Surface Water Utility Engineer 1055 South Grady Way, 5th floor Renton, WA. 98055 2 Project Overview The construction site is at the Heather Downs Detention Pond located near Union Ave SE and SE 4th St, Renton, WA. 98059. Work under this project includes re-creating stormwater quality treatment storage within an existing detention pond by excavating and disposing of approximately 510 cubic yards of native materials, installing permeable liner materials, storm drain pipes, catch basins, and removing and replacing chain link fence, asphalt concrete pavement, sidewalk, curb, and gutter. Construction activities will commence in summer 2021 and approximately complete in no later than September 2021. The following is the Erosion and Sediment Control (ESC) Plans and measures to minimize erosion and sediment transport off a construction site and protect areas of existing facilities; 1. Clearing limits Existing vegetation and trees will be preserved when the removal is not necessary throughout the project. Marking clearing limits will be considered by delineating the pond area with a continuous length of brightly colored survey tape/flagging or silt fence. Clearing limit will be installed at the beginning of project and/or prior to the clearing and/grading of the site. The Engineer will be notified 24 hours in advance of the clearing limits being staked. Marking clearing limits will be checked periodically and will be repaired or replaced if necessary. 2. Cover Measures Temporary cover such as plastic covering, mulching, seeding, and/or others equivalent BMPs as indicated in the City’s Surface Water Design Manual will be installed when an area is to remain unworked for more than seven days during dry season (May1 to September 30) or for more than two consecutive working day during the wet season (October 1 to April 30). When seeding and mulching are not possible, plastic covering will be applied or straw will be spread. If the exposed area is to remain unworked for more than 30 days, the area will be seeded with the temporary seed mix or an equivalent mix. 3. Perimeter Protection Temporary silt fence will be installed on the site downgrade prior to clearing and grading for perimeter protection to reduce the amount of sediment transported beyond the disturbed areas of construction site. Temporary silt fence will be located such that runoff from the site will be filter prior to leaving the construction site. Build-up of sediment will be removed from silt fence once it has reached 1/3 the height of the fence. Properties adjacent to the pond area will be protected from sediment deposition. 4. Traffic Area Stabilization There will be no work on SE 4th Street involved with roadway grading, but there will be minor curb, gutter, pavement repair and replacement on Union Ave SE. Stabilizing on actual traffic area is determined as not necessary. However, a temporary stone-stabilized pad or quarry spalls located at the points of vehicular ingress and egress on construction site will be installed as a temporary construction entrance to reduce the amount of mud, dirt, rocks, etc., transported onto public roads by motor vehicles. Storm drain inlet protection will be installed for nearby existing catch basins prior to project 3 construction to prevent sediment entering the storm drain system. Existing roadway will be swept clean at the end of the day. 5. Sediment Retention Surface water collected from disturbed areas of the site will be routed through low points of stormwater pond or sediment trap area. The sediment that comes with surface water will be trapped at sediment trap area, which will be installed prior to clearing and grading construction activities. Cut and fill slopes will be constructed in a manner that will minimize erosion. 6. Surface Water Collection The clearing and grading will occur in the detention pond. There will be no need to install surface water collection measures such as ditch or berms, etc. to convey the surface water to downstream sediment trap area due the fact that the clearing and grading in the detention pond is considered as a small area. 7. Dewatering Control The surface water resulting from construction activities will be treated prior to discharge or disposed of. Sediment trap will be installed to trap both sediment and surface water. Surface water will be discharged into sediment trap and pumped to a baker tank if necessary. 8. Dust Control To limit dust generation during project construction, the clearing and grading will only be performed the stormwater pond area as shown in the approved construction plans. Other approaches include the use of vacuum street sweepers, removing mud and other dirt immediately so that it does not dry and then turn into dust, limiting dust-causing work on windy days. 9. Flow Control This is a retrofit stormwater pond facility project. There will not be change in 2-year and 10-year runoff peak flow discharging from the project site during project construction; therefore, surface water from disturbed areas will not need to be routed through the project an onsite flow control facility. 10. Control Pollutants There will be a minor sidewalk, curb, and gutter removal and replacement for this project. The unused concrete (if any) remaining in the truck will not be dumped onsite. Concrete trucks will not be washed onto the ground or into storm drain system. Slurry and asphalt concrete cutting will be vacuumed during cutting and surfacing operation. Slurry and asphalt concrete cutting will not be drained to storm drain system. Sweeping materials from a pick-up sweeper will be disposed of at an appropriate disposal site. Spill response materials will be kept at the project site at all time and be used for cleaning petroleum product such as fuel, and oil. 11. Protect Existing and Proposed Stormwater Facilities and On-site BMPs Sedimentation and soil compaction resulting from construction activities are not expected to be adverse impacts to existing stormwater facilities. There are no on-site BMPs downstream or nearby needing to be protected. 4 12. Maintain Protective BMPs Pollutant protection BMPs and measures will be maintained and repaired as necessary within 24 hours to ensure its continued performance and to provide effective pollutant protection. All temporary pollutant control BMPs will be removed from the project site prior to final construction acceptance or within 30 days after achieving final site stabilization or after the temporary BMPs are determined by the engineer as no longer needed. 13. Manage the Project Installed BMPs will be inspected weekly and/or after any runoff-producing rain event. Weekly inspection will be performed at the end of work week and any needed repairs will be completed before the job is shut down for the weekend. The contractor will be responsible for maintaining, updating if necessary, and implementing SWPPP in accordance with the City’s Surface Water Design Manual. Stormwater Pollution Prevention and Spill Control (SWPPS) Stormwater Pollution Prevention and Spill Control (SWPPS) measures will be applied/installed, and maintained to prevent, reduce, and eliminate the discharge of pollutants to onsite or adjacent storm drain system or onto adjacent properties. SWPPS will address all phase of construction such as clearing, grading, and installation of storm drain pipes and catch basin structures. During project construction, SWPPS may be revised as necessary as directed by City staff to address changing site conditions or construction activities. A use of gasoline for refilling excavators and other heavy equipment is anticipated for this project. A gasoline container onsite will have a tide lip and be kept with a secondary containment. Spill cleanup and response materials will be kept onsite at all time. In the event of a spill, cleaning up the site will be immediately performed. The spill materials after the use will be disposed in accordance with applicable regulations. Asphalt concrete saw cutting, slurry, and waste materials removed from the project site (debris, earthwork, and chain link fence) will be disposed of in accordance with applicable regulations. The construction sequence is expected as follows; A. Conduct pre-construction meeting B. Flag or fence clearing limit with high visibility fencing C. Install catch basin inlet protection and other appropriate BMPs D. Remove riser from existing storm drain manhole and temporary plug storm drain pipe to pond E. Decommission monitoring well F. Grade and install stabilized construction entrance G. Construction sediment trap and set-up pump bypassing H. Remove existing concrete sidewalk, curb, and gutters I. Install storm drain pipes and catch basins and grading bottom and side slope of pond J. Repair existing concrete sidewalk, curb, and gutters K. Maintain erosion and sediment control measure or install new measures if site conditions change L. Cover all area that will not be worked more than 7 days during the dry seasons (May1 to September 30) or for more than two consecutive working day during the wet season (October 1 to April 30) 5 M. Seed any areas that remain unworked for more than 30 days N. Stabilize all areas that reach final grade within 7 days O. Remove all BMPs after project construction is completed City’s hired Contractor will be responsible for implementing ESC and SWPPS and for monitoring pollution prevention BMPs that need attention, including keeping records/reports of all inspections of pollution prevent BMPs. City’s hired contractor will also be responsible for providing spill prevention and cleanup report. Spill response materials will be kept onsite at all time. If spill cleanup materials are used, they will be disposed of in accordance with applicable regulations.