3A Public Hearing 2007 0507 - Laserfiche WebLink

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a) If the alternative site plan layout with the 25' -wide strip of open space area is selected, a vegetated swale can be installed within the open space area to help treat stormwater. A second vegetated swale could be installed in the landscape area at the southeastern entrance. Vegetated swales have a maximum treatment width of 10' and can treat an impervious area equal to 25 times the size ofthe vegetated swale. b) Flow-through planters can be installed to treat and detain roof runoff from downspouts. Like vegetated swales, the ratio of treatment area to tributary impervious area for flow-through planters is 1 :25. c) Tree well filters can also be utilized for stormwater treatment. The ratio of treatment area to impervious area for tree well filters varies with design. Additional information on stormwater treatment measures can be found in the C.3 Stormwater Technical Guidance Handbook, which is available at: http://www.eoainc.com/downloadlACCWP_C3_Technical_Guidance _ 090506-300dpi.pdf MM. The revised National Pollutant Discharge Elimination System (NPDES) Permit, issued by the San Francisco Regional Water Quality Control Board in February 2003, imposed new requirements on developers and local agencies. In addition to requiring developers to install stormwater treatment measures, developers are also required to sign a Stormwater Treatment Measures Maintenance Agreement for the maintenance of the storm water treatment measures in perpetuity. This Agreement will bind the new property owners and the Homeowner's Association (HOA) to maintain the treatment structures as recommended by the manufacturer. NN. On-site storm drain inlets shall be clearly marked with the words "No Dumping! Flows to Bay," or equivalent. 00. Landscaping shall be designed to minimize irrigation and runoff, promote surface infiltration where appropriate, and minimize the use of fertilizers and pesticides that can contribute to stormwater pollution. Existing native trees, shrubs, and ground cover shall be retained and incorporated into the landscape plan to the maximum extent practicable. A diverse selection of plants should be used to prevent a potential pest infestation from affecting the entire landscaped area. PP. Sidewalks and parking lots shall be swept regularly to mInImIZe the accumulation of litter and debris. Wash water containing any soap, cleaning agent or degreaser shall not be discharged to the storm drain and shall be collected and discharged to the sanitary sewer or collected and treated prior to being lawfully disposed. PLN2006-00 I 04 Recommended Conditions of Approval Page 12 of 16 May 7, 2007