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Date: November 23, 2009 <br />Project: MOORES GRAVEL PIT - Stormwater Management <br />Location: MESA COUNTY, COLORADO <br />Subject: WATER QUALITY CAPTURE VOLUME, (WQCV), CALCULATIONS <br />SUB -BASIN I.D. "OS -1" <br />CONDITION HISTORIC <br />WQCV = K (a (0.91 x I ^3 -1.19 x I ^2 + 0.78 x I )) in watershed Inches <br />Where: K = Adjustment to equation for Mesa County area = d6/0.43 = 0.28/0.43 = 0.65 <br />a = Adjustment for BMP's drain time. Assume retention area at 40 hours. a = 1.0 <br />1 = Watershed impervious area as a percentage. I = 30.00% = 0.3000 <br />d6 = Depth of average runoff producing storm. d6 = 0.28- inches <br />WQCV = 0.65 (1.0 x (0.91 x 0.3000 ^3 - 1.19 x 0.3000 ^2 + 0.78 x 0.3000 )) = <br />Required Storage Volume (RSV) = (WQCV / 12) x Area x F <br />Where: Required Storage Volume = Volume in Acre -Feet <br />Area = Tributary watershed in Acres = 182.1 Ac. <br />F = Adjustment factor for sediment = 1.20 <br />Required Storage Volume (RSV) = (0.0985 / 12) x 182.1 x 1.20 = <br />0.0985 watershed inches <br />1.7929 Acre -Feet = <br />78,097.62 Cubic Feet <br />