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Arks!' ne Determining Number of <br /> STORMWATER Cartridges for Systems <br /> SOLUTIONS INC. Downstream of Detention <br /> CONTECH Stormwater Solutions Inc. Engineer: JHR <br /> Date 1/24/2008 <br /> Site Information <br /> Project Name Everett Office Bldg <br /> Project State Washington <br /> Project Location Everett <br /> Drainage Area, Ad 1.44 ac <br /> Impervious Area, Ai 1.15 ac <br /> Pervious Area, Ap 0.29 <br /> % Impervious 80% <br /> Runoff Coefficient, Rc 0.77 <br /> Upstream Detention System <br /> Peak release rate from detention, Qrelease peak 0.26 cfs <br /> Treatment release rate from detention, Qrelease treat 0.02 cfs <br /> Detention pretreatment credit 50% <br /> (from removal efficiency calcs) <br /> Mass loading calculations <br /> Mean Annual Rainfall, P 36 in <br /> Agency required % removal 80% <br /> Percent Runoff Capture 90% <br /> Mean Annual Runoff,Vt 130,196 fe <br /> Event Mean Concentration of Pollutant, EMC 60 mg/I <br /> Annual Mass Load, Mtotal 487.38 lbs <br /> Filter System <br /> Filtration brand StormFilter <br /> Cartridge height 18 in <br /> Specific Flow Rate 1.0 gpm/ft2 <br /> Number of cartridges-mass loading <br /> Mass removed by pretreatment system, More 243.69 lbs <br /> Mass load to filters after pretreatment, Mpasst 243.69 lbs <br /> Estimate the required filter efficiency, Efiiter 0.60 <br /> Mass to be captured by filters, Mfilter 146.21 lbs <br /> Allowable Cartridge Flow rate, ( cad 7.50 <br /> Mass load per cartridge, Wart(Ibs) 36.00 lbs <br /> Number of Cartridges required, Nmass 5 <br /> Treatment Capacity 0.08 cfs <br /> Determine Critical Sizing Value <br /> Number of Cartridges using Qrelease treat, Nfiow 2 <br /> Method to Use: MASS-LOADING <br /> SUMMARY <br /> Treatment Flow Rate, cfs 0.08 <br /> Cartridge Flow Rate, gpm 7.5 <br /> Number of Cartridges 5_ <br /> 1 of 1 <br />