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Panera Bread Stormwater Management Report Everett,WA <br /> Existing Pervious Area: 2,202 SF=0.05 ac <br /> *PGIS= Pollutant Generating Impervious Surface <br /> See Figure 3 in Appendix A for a map of the drainage area and how it contributes to <br /> each catch basin. <br /> L. Stormwater Flow Control Plan <br /> Flow control facilities must be provided for projects where the discharges from <br /> threshold discharge areas exceed the size thresholds outlined in the City of Everett <br /> Stormwater Management Manual, Table 2.2: <br /> Table 2.2 Flow Control Requirements by Threshold Discharge Area <br /> Flow Control On-site Stormwater <br /> Facilities Management BMPs <br /> <%acres conversion of forest to lawn/landscape,or<2.5 <br /> acres to pasture <br /> a.%a acres conversion of forest to lawn/landscape,or?2.5 <br /> acres to pasture <br /> <5,000 square feet of net new effective impervious area <br /> a5,000 square feet of net new effective impervious area <br /> >_0.1 cubic feet per second increase in the 100-year flow <br /> frequency <br /> Since this project has less than 5,000 square feet of net new effective impervious <br /> area, no Flow Control Facilities are required. Furthermore, this project proposed <br /> less than 1.0 acre of land will be disturbed (see Table 1) and is not a part of a larger <br /> (re)development project therefore,the stormwater analysis may be based upon the <br /> previous (existing use) as opposed to forested conditions. An examination of the <br /> existing conditions concluded that the site currently has 0.05 acres of pervious <br /> landscaped area. This project proposes 0.17 acres of pervious landscaped area. <br /> Since the redevelopment results in a reduction of impervious area, onsite detention <br /> is not required. <br /> M. Stormwater Treatment <br /> To comply with Minimum Requirement#6: Runoff Treatment,the design and <br /> construction of a stormwater treatment facility has been performed for this project <br /> in accordance with the City of Everett Stormwater Management Manual, Volume 1, <br /> Chapter 4. A DOE approved technology for Basic Treatment(GULD rated), the <br /> BayFilter1M Model MHF-60-3 by BaySaver has been selected to treat the PGIS and <br /> landscape areas of the proposed site. The roof runoff will be collected separately <br /> and introduced to the conveyance system at the BayFilterTM by-pass manhole since <br /> Core States Group Page 19 <br />