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Coal Mine Waste <br />Table 2-2d-Runoff curve numbers for and and semiarid rangelands <br />Cover Type - Herbaceous-mixture of grass, weeds and brush <br />Hydrologic Condition <br />Soil Type <br />Curve Number <br />RUN-OFF VOLUME - POND J <br /> Precip <br />Area Acres Curve # Amount <br />Pasture 2.34 74 1.8 <br />Irrigated Hayfield 9.54 71 1.8 <br />Orchard 0.00 72 1.8 <br />Derelict 0.80 74 1.8 <br />Disturbed 19.85 87 1.8 <br />Disturbed 6.73 70 1.8 <br />Coal Waste 15.29 90 1.8 <br />TOTAL 54.55 <br />TOTAL REQUIRED WATER VOLUME - - A-F <br />SEDIMENT VOLUME - Pond J <br />Use the universal soil loss equation. <br />A=RKLSCP <br />R = rainfall factor <br />K = soil erodibility factor - Work soil <br />LS = combined length slope factor 2000' - .5% <br />C = cropping management factor - Figure 6 <br />P = erosion control practice factor <br />A = sediment, tons/acre/year <br />ONE YEAR SEDIMENT VOLUME - ACRE FEET <br />54.55 ACRES - 115 #/CF <br />TOTAL REQUIRED SEDIMENT POND CAPACITY -- AF <br />PEAK FLOW CALCULATIONS <br />The following peak flow calculations were compiled with the computer program SEDCAD <br />version 4.0. Details of the run-off calculations are shown on the following pages. <br />10-YR 25-YR <br />24 HR 24 HR <br />Event Event <br />Pond J Drainage 26.06 36.64 <br />Pond K Drainage 4.47 5.92 <br />Poor <br />D <br />90 <br />Direct <br />Run-off <br />0.26 <br />0.19 <br />0.21 <br />0.26 <br />0.75 <br />0.17 <br />0.93 <br />Flow calculations for the site ditches and culverts are presented in following sections of this exhibit. <br />Run-off <br />Vol A-F <br />0.05 <br />0.15 <br />0.00 <br />0.02 <br />1.24 <br />0.10 <br />1.18 <br />2.74 <br />2.74 <br />30.00 <br />0.37 <br />0.23 <br />1.00 <br />1.00 <br />2.55 <br />0.167 <br />2.91 <br />TR-049 Exh-8 - 164 - 08/07 <br />A PPRavED <br />6/4/09