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

Appendix D-1: Residential Sites: Runoff Reduction Credits and Treatment BMP Sizing CalculationsName of Drainage Shed:Project Located inFill in Highlighted BoxesStep 1 - Calculate Area Requiring TreatmentDrainage Shed Area acres AOpen Space and Parks Acreage*Adjusted Impervious Fraction for A ( A T ( I ) - A C ) / A = I A 0.00See Area ExampleTreatment Area A - A OS = 0.0A TBelowNumber of Units in A TNumber of units per acre in A T DU/A T =0Assumed Initial Impervious Fraction#N/AI(determine using Table D-1a)*. Includes all areas maintained in a natural state and planned for landscaped park areasTable D-1aDwelling units per acre Imperviousness1 0.172 0.253,4 0.355,6 0.407 0.508,9 0.5510-14 0.6015-20 0.70Step 2 - Calculate Impervious Area TreatmentsRunoff Reduction MeasuresEffective AreaManaged (A C )Disconnected Roof Drains use Form D-1a for credits0.00 acres(see Fact Sheet)Disconnected Pavement use Form D-1b for credits0.00 acres(see Fact Sheet)Interceptor Treesuse Form D-1c for credits0.00 acres(see Fact Sheet)Alternative Driveway Design use Form D-1d for credits0.00 acres(see Fact Sheet)Total Effective Area Managed (Credit Area) A C 0.00 acresAdjusted Area for Flow-Based Treatment A T - A C = 0.00 acresA ATA OSCheck the website for the electronic version at www.sactostormwater.org click on "new development"