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1 <br /> Design Criteria ' <br /> The City of Everett utilizes the 2010 City of Everett Stormwater Management Manual (2010 <br /> Manual) for drainage requirements. Stormwater discharges shall match developed discharge <br /> durations to pre-developed durations for the range of pre-developed discharge rates from 50% of <br /> the 2-year peak flow up to the full 50-year peak flow. The pre-developed condition to be matched <br /> shall be a forested land cover. <br /> Since development within the Narbeck Creek basin will include less than 10,000 square feet of <br /> impervious area, flow control will be provided with a detention tank designed utilizing a single- <br /> event model by limiting the peak developed rate of runoff from the 2-year, 24-hour design storm to <br /> 50 percent of the existing condition 2-year, 24-hour design storm while maintaining the existing <br /> condition peak runoff rate for the 10-year, 24-hour and 100-year, 24-hour design storms. <br /> 1 <br /> Table 1 - City of Everett Storm water Requirements <br /> Jurisdictional Requirements ' <br /> Flow Control: See above. <br /> Water Quality Volume: n/a ' <br /> Water Quality Flow Rate: <br /> Narbeck Creek Basin: n/a (no pollution generating surfaces) <br /> Powdermill Gulch Creek Basin: 0.1542 cfs (adjusted for 15 minutes) ' <br /> Downstream Analysis: <br /> Level 1: %a mile downstream <br /> 1 <br /> 1 <br /> 1 <br /> 1 <br /> 1 <br /> 6/16/2011 Stormwater Site Plan Page 4 <br /> 1 <br />