Stormwater Quality Design Manual (May 2007) - City of Sacramento ...

Step 3 - Calculate Flow or Volume Requiring TreatmentForm D-2c Treatment - Flow-Based (Raional Method)Calculate treatment flow (cfs):Look up value for i in Table D-2c (Rainfall Intensity)Flow = Runoff Coefficient x Rainfall Intensity x Areaselect a location on page1iTable D-2cRainfall IntensityRoseville i = 0.20 in/hrObtain A AT from Step 2 0.00 A AT Sacramento i = 0.18 in/hrFolsom i = 0.20 in/hrUse C = 0.950.95 CFlow = 0.95 * i * A AT#VALUE!cfsForm D-2d Treatment - Volume-Based (CASQA)do not use form D-2d contiue to form D2-eCalculate treatment volume (Acre-Feet):Determine Adjusted C A using Table D-2d (for CASQA Method)and the Adjusted Impervious Fraction (I A ) from Step 2Treatment Volume = Area x (Storage Volume ÷ Conversion Factor)0.04C ADetermine Unit Basin Storage Volume (Figure D-2a) using C A0.03 SVA from Step 1Treatment volume = A x (SV / 12)0.00 A0.00 Acre-FeetForm D-2e Treatment - Volume-Based (ASCE-WEF)Calculate water quality volume (Acre-Feet): WQV = Area x Maximized Detention Volume (P 0 )Obtain A from Step 1 0.00 A hrs Specified Draw Down timeObtain P 0 : Maximized Detention Volume from figures E-1 to E-4in Appendix E of this manual using I A from Step 2.#N/AP 0Calculate treatment volume (acre-ft):Treatment volume = A x (P 0 / 12)#N/AAcre-FeetCheck the website for the electronic version at www.sactostormwater.org click on "new development"