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Asa-3 <br />q - qp (Ad)(Q) <br />q = hydrograph coordinate discharge in cfs (cubic feet per second) <br />q =csm/inch (cubic feet per second per square mile per inch of <br />P runoff) <br />Ad = drainage area in square miles <br />Q = runoff in inches <br />Assumptions: 1. Time of Concentration = .25 hrs. <br />2. Time of Travel = 0 <br />3. Drainage Area North of Central Facilities Access Road = <br />22.0 Ac (@ culvert) & 14.0 Ac South of Road <br />Solution: From Table 5-3 - Tabular Discharges for Type II Storm <br />Distribution (csm/inch) <br />q = 727 w/Tt= 0 <br />P <br />10-year, 24-hour Peak Discharge <br />q10 qp Ad Q10 <br />q10 - 727x22.Ox0.58x1.562x10-3 = 14.49 cfs <br />q10 - 727x14.Ox0.58x1.562x10 3 = 9.22 cfs <br />25-year, 24-hour Peak Discharge <br />q25 = qp Ad Q25 <br />q25 = 727x22.Ox0.87x1.562x10-3 = 21.73 cfs <br />Use the above peak discharges, q 0 and q25, for the inlet ditch design <br />flow and the emergency spillway design flow, respectively. <br />Reservoir Liquid Volume: <br />Sedimentation Reservoir shall contain the total volume from a <br />10-year, 24-hour precipitation event. <br />Detention time for the runoff shall depend upon the water <br />quality. Once the water quality meets or exceeds the <br />standards as set forth in the mine permit, the reservoir shall <br />be dewatered by pumping. <br />Volume Surface Runoff, Vsr = Q10 x Ad <br />12 in/ft <br />Liquid Volume: <br />Vsr = 0.58 <br />12 <br />x 35.6 Ac = 1.72 <br />74.923 <br />Ac-Ft <br />Cu-Ft <br />