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Subwatexshed I <br />L = 3600' <br />H = 700' <br />tc = 0.133 hrs <br />Subwatershed II <br />L = 4000' <br />H = 750' <br />tc = 0.146 hrs <br />SUbwatershed III <br />L = 3800' <br />H = 600' <br />tc = 0.514 hr5 <br />SedimPntolagv <br />The SEDCAD+ catg~uter program was alsa utilized to calculate the <br />~1~mPntolOgy of each watershed using the revis~3 universal soil loss <br />equation (RUBLE). A total of 7.20 acre feet is provided for sediment <br />storage in Pond 008. Using a density of 80 pounds/cubic foot, 12,545 tons <br />or approximately 8.o RUBLE 10-year, 24-hour storm event equivalent storage <br />is provided for sediment storage. Peabody will restore adequate c~rlima„t <br />storage to the pond when the available sediment storage becomes 2.88 <br />acre-feet or less (40 percent remainircf sediment storage). <br />Particle Size Distributions. the particle size distribution for this <br /> <br />cxl;nwnt pond was based on sieve and hydrometer analysis of various soil <br />types in the permit area. 'This distribution is representative of each of <br />the subwatersheds and based on a weighted average. <br /> TABLE 7-6f-11 <br /> Bed imentology Size Analysis <br /> Weighted Average <br /> Percent Finer <br /> SUbwatershed S~bwatershed SUbaatershed <br />Size (mm) I II IIZ <br />12.7 100 100 100 <br />11.2 94 98 97 <br />2.0 84 94 92 <br />1.0 82 88 89 <br />0.5 81 84 87 <br />0.25 80 80 85 <br />0.106 76 76 81 <br />0.045 50 54 44 <br />0.02 30 38 35 <br />0.01 21 28 25 <br />0.005 17 20 19 <br />0.002 13 11 14 <br />0.001 10 6 10 <br />0.0001 0 0 0 <br /> 7-6f-10 Revised 08/21/91 <br />• <br />• <br />• <br />