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

Appendix D-2: Commercial and Multi-Family Sites*: Runoff Reduction Credits and Treatment BMP Sizing CalculationsName of Drainage Shed:Location of project:Step 1 - Calculate Area Requiring TreatmentFill in Higlighted boxesDrainage Shed Area acres AOpen Space Acreage and Landscaped Areas** acres A OSArea with Runoff Reduction Potential A - A OS = 0.00 acres A Tsee areaexample belowAssumed Initial Impervious Fraction A T / A = 0.00I*. Includes apartments, condominiums, and townhouses**. Includes all areas maintained in a natural state and planned for landscapingStep 2 - Calculate Impervious Area TreatmentsRunoff Reduction TreatmentsPorous Pavement:ImperviousAreaManagedEfficiencyFactorEffective AreaManaged (A C )Option 1: Porous Pavement acres x = 0.000 acres(see Fact Sheet, excludes porous pavement used in Option 2)Option 2: Disconnected Pavement use Form D-2a for credits 0.00 acres(see Fact Sheet, excludes porous pavement used in Option 1)Landscaping used to Disconnect Pavement acres = 0.00 acres(see Fact Sheet)Disconnected Roof Drains acres = 0.00 acres(see Fact Sheet and/or Table D-2b for summary of requirements)Ecoroof acres = 0.00 acres(see Fact Sheet)Interceptor Trees use Form D-2b for credits 0.00 acres(see Fact Sheet)Total Effective Area Managed A C 0.00 acresAdjusted Area for Flow-Based Treatment A T - A C = 0.00 A ATAdjusted Impervious Fraction A AT / A = 0.00 I ATable D-2aTable D-2bPorous Pavement TypeEfficiencyMultiplierMaximum roof sizeMinimum traveldistanceCobblestone Block Pavement 0.40 ≤ 3,500 sq ft21 ftPervious Concrete/Asphalt0.60Pavement≤ 5,000 sq ft24 ftModular Block Pavement &0.75Porous Gravel Pavement≤ 7,500 sq ft28 ftReinforced Grass Pavement 1.00 ≤ 10,000 sq ft32 ftCheck the website for the electronic version at www.sactostormwater.org click on "new development"