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Bypass <br /> Developed Area: 0.04 ac <br /> Hydrologic Soils Group C (Till) <br /> Impervious Area: 0.04 ac <br /> Pervious Area 0.00 ac (Landscaping) <br /> Basin to Detention Pipe <br /> Developed Area: 0.20 ac <br /> Hydrologic Soils Group C (Till) <br /> Impervious Area: 020 ac <br /> Pervious Area 0.00 ac (Landscaping) <br /> Develo ed Condition Event Out ut: WINHM3 <br /> Peak Flow (cfs) Area ac <br /> 2- r mitigated 0.014 0.24 <br /> 10-yr mitinated 0.026 0.24 <br /> , 100-yrmiticated 0.048 __ �.24 <br /> B. PERFORMANCE o fANDARDS <br /> l�hc Cit} of Gvcrctt 2010 Stonm�atcr Managcmcnt �4anual as��cll ar tf,c DOIi <br /> 2005 Stormwatcr�'anagement Manual for Wcstem Washington �cere uscd in thc <br /> dcsigu of the stomn��atcr mitigation plan for this nrojcct. <br /> C. FLOW CONTROL SYSTEM <br /> Flow control for this project will be provided with a detention pipe serving lhe <br /> disturbed portion of the site oniy. The pipe has been sized using VWVHM3 as <br /> approved in the DOE Stormwater Manuai <br /> D. WATER QUALITY SYSTEM <br /> Since this project is in the combined s':ormisewer basin treatment of the runoH will be <br /> provided at the COE treatment plant and this projzct is exempt from runo!i treatment per <br /> interim Public Works Policy #2-11. <br /> E. CONVEYANCE SYSTEM ANALYSIS <br /> i Maximum Flows from on-site developed area: <br /> For this project the entire 0.24 acres of impervious wes analyzed for the peak 100-year <br /> ilow rate to ensure the system as designed couid handle :he expected flows. Using the <br /> WWMH3 software a peak 100-year flow rate of 0.15 cfs. Using Manning's Equation the <br /> mir,imum conveyance capacity cf the new storm pipes as designed is 0.6 cfs whic.h is <br /> four times greater than the flows from the entire basin. Therefore, tnis system has more <br /> than adequate capacity for the expected flovis. <br /> -- 11-1t5 <br /> Glr.ir:r Piopertie; Paae-1J <br /> L�:��.i1�l,ei '�1 1 ' <br />