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S't'OR,bIR'ATER SII'L PLAN <br />AUGUST:1 NOODS CONDOb11NIUMS <br />D1AY 20, 2003 <br />Pr1GG 7 <br />RliNUFF CALCULATION: <br />Thc ups.rcum basin consist� of approximately 122 acres north of d�e site, from West <br />C,�sino Road, south. The tributary arca has been deterniincd from ti�e Snohomish Count�• <br />crial mapping and fefd investigation. This includes a large portion of the Walter E I-fall <br />i;olf Course. No culverts �vere evideut under �Vest Casino Road. The new dcvclopment <br />is expected to mect the requirements of the QUE Desigu Manual. <br />Land Use CN Area ac <br />[mpervious 98 30.0 <br />Grass 36 92.0 <br />Thc flow path for thc timc of concentration calculation consists of thc Collowing: <br />Plo�•:� TYPe _ Lem�d� (ft) Slo c tt/ft Ti��min <br />Sheet Flow (grass) 300 0.03 28.8 <br />Shallow Plow (gr��ss) 700 0.10 3.4 <br />Channel Flow (swalc) 1300 0.005 2�,2 <br />l�otal tic of concentration = 53.4 minutcs. <br />Thc upstrcam runoff rates arc: <br />Rcturn Period Peak Rate(cfs) Volume�Q <br />2 Ycar ] 3.0 317,8 I-1 <br />100 Ycar 4d.1 943,31 U <br />CULVGR"C S17ING: <br />The proposed cuh�crts are 33"x �7" CSP arch pipc widi 2-2i3"rl/2" co!-rugations and will <br />bc dcpresscd 20 perccrt into the stream bcd. Appendix A indudcs a spreadsheet e�hich <br />calculatcs thc hcad�vatcr clevation tor thc 2 and 100 yr cccnts Uascd upon Inlct Control <br />and Outlet Control �is mprescntcd in thc DOG Manuul. <br />JIL��rnsor.Cr,�.,��hu9usuu9co �SdePianO]-,9)TDccumenisi55P9]�O]]pOCDWH/Sffil � <br />