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� <br />PreIiminary detention calcularion in accordance with City of Everett d�;�ign critPaia <br />demonstrate a neec! for 17,533 cunic feet of detention stcnge, (see E�:iuhit "F") and <br />— 2i5 L.F, of biofiltr3tion swsle. Preliminary calc��ia6ons'ay hydregraph meihodolog• <br />(as requuE:u by The Dept. of Fisheries) for release of �:1; oi the existing 2 year p� <br />f�r th� developed 2 year runoff and matching developed release oi the 10 and 100 year <br />— storm at the exisdng p�a�s necessitate a pond volume of approumately 15,000 cubic <br />feet. The Department of Fisheries further requires upsizing of the pond by 50% when <br />using the hydrograph method of analysis. <br />Final design of the pond provides a volume of approximately 22,650 cubic feet of <br />active detendon storage. See "Appendix A" for hydrograph data. <br />�' The �ond and swale will be constructed along the easterly boundan• of the site and <br />;, adjacent to the existing City owned right of way for 104th Street SW. Outflow from <br />the deten6on facility will be d'uected to a pipe system (constructed within the City <br />owned right of way) to convey the controlled runoff w the existing wetland. Outfall <br />r from the storm system will be through an exfiltration trench above the wetland <br />�`' boundary to provide release as sheet flow into the existing wetland. <br />�w <br />!, <br />Drainage Report <br />Frontier Bank <br />Page 2 <br />