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• <br />Area Acres Curve # Amount Run -off <br />Vol A -F <br />Disturbed -Poor 0.60 87 1.8 0.75 <br />0.04 <br />Disturbed -Good 2.82 74 1.8 0.26 <br />0.06 <br />Disturbed -Fair 0.97 81 1.8 0.48 <br />0.04 <br />Coal Waste 3.47 90 1.8 0.93 <br />0.27 <br />TOTAL 7.86 <br />0.41 <br />TOTAL REQUIRED WATER VOLUME - - A -F <br />0.41 <br />SEDIMENT VOLUME - Pond D <br />Use the universal soil loss equation. <br />A= RKLSCP <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 />Three Year Sediment Volume - Acre -Feet <br />0.03 <br />7.86 ACRES - 115 # /CF <br />Total Required Sediment Pond Capacity - Acre -Feet <br />0.44 <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 6.8 <br />Flow calculations for the site ditches and culverts are <br />presented in following sections of this exhibit. <br />U <br />Spillway Pond D <br />Pond D Emergency Spillway <br />Manning's Equation <br />Flow In a Trapezoidal Channel <br />DEPTH D 0.5 FEET <br />TR -64 <br />A F P R OV6A <br />) z�z8Jo9 <br />Exh 8 -18 <br />08/09 <br />