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K:\01904-610\Admin\Docs\2020 Update\Appendix B - References\Credit Valuation Guide_20200611.docx (1) 1 ∗0.1 ∗ = 1.656 /! · Therefore, 1.656 credits are generated from capturing the runoff of one new acre of impervious surface. · One volume reduction credit is sufficient to cover a-linear project of 26,300 ft2 of new impervious surface. · One credit is equal to 1 acre-foot of infiltration per year. Equivalence of One Credit: · The BMP size requirements for one acre of net new impervious surfaces are as follows: (2) 1 ∗ 1.0 "#ℎ% ∗ = 0.0833 ( )*+ ,(-./ · Capturing runoff from one acre of impervious surface generates 1.656 credits, and 1 acre of net new impervious requires 0.0833 acre feet of BMP capacity. Therefore, the number of credits required in terms of impervious area can be determined: (3) . 234.5<5 6 = 7 234 6 1 8" = 0.0503 )*+ · The amount of impervious surface that requires a 0.0503 acre-foot (2,191 ft3) BMP can be determined using the 1.0” standard for linear projects. Determining the Value of One Credit · By using credits, more of the purchased land can be used towards development. Therefore, the amount saved by a developer includes both property value and cost of BMP implementation. · In Hugo, land costs approximately $1.50/square foot2. · For consistency, a value of 1 acre of impervious surface will be evaluated. · Using equation two, the BMP required is 0.0917 acre feet, or 4000 cubic feet. · Standard stormwater ponds average three to four feet in depth for a permanent pool3. Approximately the same area is commonly needed for live storage. Therefore, the area saved by utilizing credits is estimated to be 2,300 square feet, or $3500 at $1.50 per square foot: 4000 .=" > 3.5 = 1143 %?. ∗ 2 ( -", %(A = 2,286 %?. · Assuming an average of $6.80 per cubic foot3 and multiplying by the required 4000 cubic feet a BMP of the required size is estimated to cost $27,200.