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Riverside Road (E-W)will be reconstructed in kind where disturbed for utility upgrades. These reconstructed <br /> areas are not included in the table below. The proposed improvements add Non Pollution Generating <br /> Impervious Surface (NPGIS)to Riverside Road (N-S) and Riverside Road (E-W)with the installation of the <br /> widened sidewalk and gravel buffer strip. Pollution Generating Impervious Surfaces (PGIS) include Eighth <br /> Street construction and Riverside Road driveways. Eighth Street adds additional NPGIS sidewalk as well. <br /> See Table 8.0 below for a summary of the new surfaces proposed with the project. See Appendix A for the <br /> Developed Hydrology figure showing these areas. <br /> Table 8.C: Developed Areas <br /> Land Cover Area <br /> New Pervious 0.17 AC <br /> New NPGIS 0.73 AC <br /> New PGIS 0.68 AC <br /> Existing Area to Remain 2.59 AC <br /> Limit of Work 4.17 AC <br /> See Appendix A for the site development plans showing the proposed improvements. <br /> D. FLOW CONTROL <br /> According to Section 2.2.7 of the 2010 City of Everett Stormwater Management Manual,the Snohomish River is <br /> a flow control exempt water body;therefore, no flow control is proposed. Interior lots of the Riverside Business <br /> Park will be permitted separately and may be subject to flow control based on existing outfall capacities. <br /> E. STORMWATER TREATMENT PLAN <br /> Riverside Road (N-S), Riverside Road (E-W), and Stormwater Quality Pond 2 were designed and permitted in <br /> 2000. See Appendix C for the Stormwater Site Plan (Comprehensive Hydraulics Report),April 2000, by Reid <br /> Middletown documenting the storm drainage design of the roads and pond. As shown on Figure 2 of the April <br /> 2000 report, Stormwater Quality Pond 2 has a designed basin of 59 acres, of which 31 acres is PGIS and 23 <br /> acres is rooftop impervious surface. <br /> The original design of the pond assumes that the interior lots of the Riverside Business Park will be directing <br /> all runoff up to the water quality event with additional allotments of partial areas up to the 25-year return event <br /> to the Riverside Road pumped storm drain system. The pumped storm drain system outfalls directly to <br /> Stormwater Quality Pond 2. At the time of the original development, overflows for events exceeding the 25- <br /> year return event were not considered. <br /> Riverside Business Park—Public Access Trails and Roadway Improvements <br /> 7 <br />