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Disturbed -Fair 0.24 81 1.8 0.48 <br />0.01 <br />Coal Mine Waste 6.60 90 1.8 0.93 <br />0.51 <br />TOTAL 14.60 <br />0.94 <br />TOTAL REQUIRED WATER VOLUME - - A -F <br />0.94 <br />SEDIMENT VOLUME - Pond D <br />Mannings "N" <br />Use the universal soil loss equation. <br />0.03 <br />A=RKLSCP <br />X <br />R = rainfall factor <br />30.00 <br />K = soil erodibility factor <br />0.37 <br />LS = combined length slope factor 400' - 2% <br />0.31 <br />Use Ditch D1 Length & Slope <br />C = cropping management factor <br />1.00 <br />P = erosion control practice factor <br />1.00 <br />A = sediment, tons/acre/year <br />3.44 <br />Two Year Sediment Volume - Acre -Feet <br />0.04 <br />14.60 ACRES -115#/CF <br />Total Required Sediment Pond Capacity - Acre -Feel <br />0.98 <br />Peak Flow Calculations <br />The following peak flow calculations were compiled with SEDCAD. <br />Details of the run-off calculations are shown on the following pages. <br />25 -YR <br />24 HR <br />Event <br />Pond D Drainage 14.1 <br />Flow calculations for the site ditches and culverts are <br />presented in following sections of this exhibit. <br />Spillway Pond D <br />Pond D Emergency Spillway <br />Manning's Equation <br />Flow In a Trapezoidal Channel <br />DEPTH <br />D <br />0.4 <br />WIDTH <br />W <br />10 <br />Slope <br />S <br />0.02 <br />Mannings "N" <br />N <br />0.03 <br />SIDE SLOPE <br />X <br />2 <br />AREA=(W"D)+(X*D2)= <br />WETTED PERIMETER=(W)+2*[((X*D)2+D2)112] <br />FEET <br />FEET <br />EXPRESS AS DECIMAL <br />EXPRESS AS DECIMAL <br />SLOPE = X:1 <br />4.20 Feet2 <br />11.74 Feet <br />11.73 <br />TR -98 Exh. 8-18 01/15 <br />