Res07 14829 - Laserfiche WebLink

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12/17/2007 Practices (BMPs) for the control of point and non-point source pollutants in stormwater and constitute the Stormwater Pollution Prevention Plan (SWPPP). Project grading shall not commence (no grading permit shall be issued by the City) until an NPDES permit is issued, demonstrating that project erosion control and stormwater treatment measures, including the project SWPPP, meet SWRCB requirements. The project shall be required to fully implement the erosion control and other water quality measures cited in the SWPPP and to monitor these measures during a specified period following completion of project construction. The RWQCB would be responsible for inspecting these measures, typically on an annual basis, while the sponsor would be responsible for implementing any remedial measures if the Board indicated that site stormwater quality objectives were not being met. The City Engineering Division would also be responsible for post-construction inspection of all measures that would eventually become part of the maintained infrastructure of the project, including source control and water quality treatment measures. Findings: Implementation of these measures would reduce the construction- related soil erosion and sedimentation impacts to a less-than-significant level. B. Increased Stormwater Contaminant Loadina - Potential Violation of Water Qualitv Standards Potential Impact 9-2: The proposed project would result in incremental increases in the stormwater contaminant loading for some heavy metals, as well as oil and grease and pesticide/herbicide residues. Project contaminant input could further impair the already impaired quality of stormwater discharged to Redwood Creek, which has included (from various sources in the area) copper, hydrocarbons, PCBs, and DDTs in excess of EPA thresholds. This possible project effect is considered a potentially significant impact. Mitigation 9-2: Apply the following site-appropriate Best Management Practices (BMPs) or their equivalents as part of the project Stormwater Pollution Prevention Plan (SWPPP), including measures required to comply with the C.3 regulations adopted as part of the San Mateo Countywide Stormwater Pollution Prevention Program (STOPPP), in order to comply with the requirements of the NPDES General Permit and imminent updating of the Municipal Stormwater Permit for Redwood City: 1. Integrate start-at-the-source measures for stormwater control and treatment into the project stormwater drainage design. Such measures could include pervious parking lots, infiltration basins, vegetated (grass) swales ("bioswales"), or other measures designed to minimize stormwater runoff (through maximization of local infiltration and detention storage), settle out fine sediments, and filter contaminants. Oil/grease traps, sand filters, or similar in-line filtration systems for storm drain systems should also be considered. Such traps, filters, or separators must be accompanied by a clean out/maintenance program that ensures acceptable trap efficiencies, specifies appropriate disposal procedures, and reduces the risk that the traps become sinks for pollutants. 2. Institute a regular schedule of street and parking lot sweeping. The frequency of cleaning shall be higher (twice monthly) during the winter rainy season, yet maintained year-round. Regular cleaning of paved surfaces reduce the "first flush" phenomenon wherein the highest concentration of contaminants are flushed off the surfaces during the early portion of a runoff event. Cleaning Atty/Reso/Reso.1772 121707 24 14829 Muff# 613