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DETENTION BASIN SC'~LE <br />i Volume Calculations: (SCS, 1977) MIDDLE CREEK ENERGY MINE ~3 <br />Undisturbed/Reclaimed Area, ac. (CN=70) 6.2 23.2 <br />Dis`~urbed Area, ac. (CN=82) 94.8 98.2 <br />Total Area, ac. R tC ~I~ ~fl 101.0 121.4 <br />'weighted AMC-II Curve Number ~~~ 81 80 <br />25-yr, 24-hr, Rainfall, in. OGT ~ ~ 1904 2.1 2.1 <br />Z5-yr, 24-hr, Runoff, in. ppINED LAND RECLP.MaTION DfvlsiQ:67 0.62 <br />25-yr, 24-hr, Runoff, ae-ft. Colo. Dept. of Natural Reseurces5.70 6.27 <br />/O-yr~ 24-tir ~ 12o~„fall ~ in. I. 8 1.8 <br />!O-yr~ 24-~r~ Ru.,o~~, ac-~~. H. D`1 y.y$ <br />Discharge Calculations: (SCS, 1977) <br />Type II Storm Discharge, cfs/in. 96 110 <br />Uncorrected Storm Discharge, cfs. 64.3 68.2 <br />Slope Correction 0.93 1.0 <br />Shape Correction 0.64 1.50 <br />Corrected Peak Flaw, cfs. 38.3 102.3 <br />SalilwaY Calculations: (Broad-crested weir design; Haan, Barfield & Warner, 1981) <br />Exit Slope, ft/ft. 0.03 0.03 <br />Exit 'Jelacity, fps. 5.0 5.0 <br />Mannings n (riprap channel) 0.04 0.04 <br />Critical Energy Head (Het), ft (Fig. 48.14} 1.10 1.10 <br />Reserviar Head (Hp), ft. (Fig. 48.1) 1.55 1.55 <br />Q` = 0.544(g)~(Hec)3/2(b) 595.70 356.14 <br />5 = ((Q/Q` x 150} _ (z x Hec))/1.5 6.1 26.5 <br />Hec = yc + Vc2 <br />2g <br />Yc = depth of flaw <br />Vc = critical velocity <br />g = gravitational constant <br />Spillway Bottom 411dth, ft. 10.0 30.0 <br />Spillway Side Slope, ftlft. 0.5 0.5 <br />