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I <br /> ,ll4I/46.tTeAvo Determining Number of <br /> I <br /> ill e"'''!j►rr1 a,i.`:n <br /> STORMWATER Cartridges .for Systems <br /> •--- . -' LUTIO S NC. Downstream of Detention <br /> I <br /> Determining Number of Cartridges for StormFilter Systems <br /> I CONTECH Stormwater Solutions Inc. Engineer: KET Blue Cells= Input <br /> Date 6/1/2011 Black Cells= Calculation <br /> Site Information <br /> I Project Name Project State Seaway Lot 3B and Norpro <br /> Washington <br /> Project Location Everett <br /> Drainage Area,Ad 0.69 ac <br /> I <br /> Impervious Area,Ai 0.25 ac <br /> Pervious Area,Ap 0.44 <br /> % Impervious 36% <br /> I Runoff Coefficient, Rc 0.38 <br /> Upstream Detention System <br /> Peak release rate from detention, Qrelease peak 0.240 cfs <br /> I <br /> Treatment release rate from detention,Qrelease treat 0.004 cfs <br /> Detention pretreatment credit 50% <br /> (from removal efficiency calcs) <br /> I <br /> Mass loading calculations <br /> Mean Annual Rainfall, P 37 in <br /> Agency required % removal 80% <br /> Percent Runoff Capture 90% <br /> I <br /> Mean Annual Runoff,Vt 31,368 ft3 <br /> Event Mean Concentration of Pollutant, EMC 100 mg/I <br /> Annual Mass Load, Mtotai 195.71 lbs <br /> INumber of cartridges -mass loading <br /> Mass removed by pretreatment system, Mpfe 97.85 lbs <br /> I Mass load to filters after pretreatment, Mpasst 97.85 lbs <br /> Estimate the required filter efficiency, Ef,ter 0.60 <br /> Mass to be captured by filters, Mfilter 58.71 lbs <br /> I <br /> Allowable Cartridge Flow rate, Qeart 7.5 gpm <br /> Check that Qoart can meet Efilter OK <br /> Number of Cartridges required, Nmass 2 <br /> I <br /> Treatment Capacity 0.03 cfs <br /> Determine Critical Sizing Value <br /> Number of Cartridges using Qrelease treat' Nfiow 1 <br /> IMethod to Use: MASS-LOADING <br /> SUMMARY <br /> I <br /> Treatment Flow Rate, cfs 0.03 <br /> Cartridge Flow Rate, gpm 7.5 , <br /> Number of Cartridges 2 <br /> I <br /> I12021-B NE Airport Way <br /> ©2006 CONTECH Stormwater Solutions Portland, OR 97220 <br /> I <br /> contechstormwater.com Phone: 800-548-4667 Fax: 503-258-3190 1 of 1 <br />