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' o a <br /> 5.6 Minimum Requirement#6: Runoff Treatment <br /> The permanent pool portion of the wetpond has been designed according to the 1997 City of <br /> Everett Stormwater Management Manual. The facility has been designed to contain the volume <br /> of runoff from the 6-month, 24-hour design storm, in the developed basin scenario. A minimum <br /> ' of 15% of the 6-month volume is designed to be within a vegetated treatment cell. <br /> The existing detention pond constructed for the South Storage Yard project was as-built and <br /> found to have sufficient storage to provide runoff treatment for both the South Storage and <br /> Building Addition projects. The total required volume is 8,834 cubic feet(additional <br /> StormSHED sizing calculations can be found in Appendix C). The required minimum treatment <br /> ' volume in the second vegetated treatment cell is 1,325 cubic feet. The tables below show the as- <br /> built volume in each treatment cell. <br /> ' First WQ Treatment Cell Second Vegetated Treatment <br /> Cell (min 15%total volume) <br /> Elev. Area (ft2) Vol (ft) Elev. Area(ft2) Vol (ft) <br /> 558 918 0 560 550 0 <br /> 559 1,249 1,084 561 1,803 1,177 <br /> ' 560 1,595 1,422 562 2,414 2,109 <br /> 561 1,993 1,794 Total: 3,285 <br /> 562 2,422 2,208 <br /> Total: 6,507 <br /> 1 <br /> DAVID EVANS AND ASSOCIATES,INC. <br /> OPERATIONS CENTER ADDITION JUNE,2010 <br /> STORMWATER SITE PLAN PAGE 7 <br />