Worksheet : Alternative Compliance Volume Worksheet Step 1: Determine the alternative compliance volume without water quality credits Determine the capture efficiency achieved in upstream BMPs X1= % 1 , X1 (%) Enter design capture storm depth from , d (inches) d= inches 2 Using , pivot from where X1 intersects the curve to determine the fraction of design capture storm depth remaining to be Y1= 3 met, Y1 Calculate the design depth that must be managed in inches 4 alternative compliance BMPs, dalternative = Y1 × d Compute the alternative compliance volume corresponding to dalternative the hydrologic methods described in Section , ACV= cu-ft 5 ACV (cu-ft) Step 2: Determine Credit Volume Method 1: Determine Credit Volume on Reducing Impervious Footprint Enter design capture storm depth from , d (inches) d= inches 1 Using d, calculate the DCV using the pre-project imperviousness and the methods described in , DCVpre DCVpre= cu-ft 2 Using d, calculate the DCV using the proposed 3 imperviousness and the methods described in , DCVpost DCVpost= cu-ft (cu-ft). Credit Calculate the Credit Volume = DCVpre - DCVpost (cu-ft). cu-ft 4 Volume= Method 2: Determine Credit Volume based on Project Type and Density Determine the sum of the Credit Percentages applicable to ∑Credit the Project, Percentages (%). (See Section 2.4 of % ∑Credit = Percentages 1 the WQMP) Enter design capture storm depth from , d (inches) d= inches 2 d, calculate the DCV using the proposed DCVpost no imperviousness without BMPs and the methods described in cu-ft BMP= 3 , (cu-ft). DCVpost no BMP Calculate the Credit cu-ft 4 Credit Volume = DCVpost no BMP × Percentages Volume= ∑Credit Step 3: Determine the Alternative Compliance Volume after WQ Credits Enter design capture storm depth from , d (inches) d= inches 1
Worksheet : Alternative Compliance Volume Worksheet Step 1: Determine the alternative compliance volume without water quality credits 1 Determine the capture efficiency achieved in upstream BMPs , X1 (%) X1= % 2 Enter design capture storm depth from , d (inches) d= inches 3 Using , pivot from where X1 intersects the curve to determine the fraction of design capture storm depth remaining to be met, Y1 Y1= 4 Calculate the design depth that must be managed in alternative compliance BMPs, dalternative = Y1 × d inches 5 Compute the alternative compliance volume corresponding to dalternative the hydrologic methods described in Section , ACV (cu-ft) ACV= cu-ft Step 2: Determine Credit Volume Method 1: Determine Credit Volume on Reducing Impervious Footprint 1 Enter design capture storm depth from , d (inches) d= inches 2 Using d, calculate the DCV using the pre-project imperviousness and the methods described in , DCVpre DCVpre= cu-ft 3 Using d, calculate the DCV using the proposed imperviousness and the methods described in , DCVpost (cu-ft). DCVpost= cu-ft 4 Calculate the Credit Volume = DCVpre - DCVpost (cu-ft). Credit Volume= cu-ft Method 2: Determine Credit Volume based on Project Type and Density 1 Determine the sum of the Credit Percentages applicable to the Project, ∑Credit Percentages (%). (See Section 2.4 of the WQMP) ∑Credit Percentages = % 2 Enter design capture storm depth from , d (inches) d= inches 3 d, calculate the DCV using the proposed imperviousness without BMPs and the methods described in , DCVpost no BMP (cu-ft). DCVpost no BMP= cu-ft 4 Calculate the Credit Volume = DCVpost no BMP × ∑Credit Percentages Credit Volume= cu-ft Step 3: Determine the Alternative Compliance Volume after WQ Credits 1 Enter design capture storm depth from , d (inches) d= inches