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Asd-3 <br />Equivalent Area: <br />• 1 = 209x6 where 1 = 600' a = 5.80 acres <br />Peak Discharge: <br />From Figure S1-A (page 18) <br />For CN = 80 and area = 5.8 cfs/inch = 10.9 <br />Equivalertit Discharge: <br />QE10 = 10.9 x 1.17 x 0.39 = 4.97 <br />QE25 = 10.9 x 1.17 x 0.62 = 7.90 <br />Actual Discharge: <br />Q1(I = 4.97 ( 5.80 ) ='3.15 cfs <br />Q2~; = 7.90 ( 5:80 ) = 5.00 cfs <br />UsEa above Q25 = 5.00 cfs for the emergency spillway designs. <br />Since the flow will be divided in 2 ditches, size the col- <br />lector ditches for ~ 410 or i.6 cfs. <br />• Reservoir Liquid Volume: <br />Sedimentation Reservoir shall contain the total volume from <br />a :l0-year, 24-hour precipitation event. <br />Detention time for the runoff shall depend upon the <br />water quality. Once the water quality meets or ex- <br />ceeds the standards as set forth in the mine permit, <br />the reservoir shall be dewatered by pumping. <br />Volume Surface Runoff, Vsr = Q10 x Ad <br />12 in/ft <br />Liquid Volume: <br />Vsr = 0.39 in x 3.67 = 0.12 Ac-Ft <br />12 in ft <br />= 5195 Cu-Ft <br />Allow liquid volume for 1.5-10-year events <br />Vsr = 0.18 Ac-Ft <br />7840 Cu-Ft <br /> <br />JAN 2'c ~~~~ <br />