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Since the sediment storage capacity is less than three years, Peabody Coal Company will <br /> monitor the sediment storage capacity to ensure enough capacity is available. The <br /> estimated design storm sediment volume is based on a worst case distrubance in the <br /> watershed. This worst case will not occu r until approximately 1995. Therefore the <br /> constructed sediment storage capacity should be adequate for at least three years. <br />Particle Size Distributions. The particle size distribution for this sedimentation pond <br />was based on sieve and hydrometer analysis of various soil types in the Seneca Il-Y permit <br />area. This distribution is representative of the watershed for Pond 005 and based on a <br />weighted average. The specific gravity and the submerged bulk specific gravity of the <br />soil ere estimated to be 2.50 and 1.17, respectively. <br />Sedimentology Size Analysis <br />Weighted Average <br /> Percent <br />Size (mm) Passing_ <br />12.7 100 <br />11.2 97 <br />2.0 91 <br />• .. 1.0 87 <br />0.5 84 <br />0.25 82 <br />0.106 79 <br />0.045 56 <br />0.02 40 <br />0.01 31 <br />0.005 24 <br />0.002 17 <br />0.001 14 <br />length-SIoDe Factor (LS). The fang [hslope is described as the typical length-slope for <br />the subwatershed and the distance from the point of origin of overland flow to a point <br />vhere the slope decreases such that significant deposition occurs or until the flow enters <br />a defined channel. The length-slope for Pond 005 was determined to be between 300 and 400 <br />feet, and the average slope was determined [o be 22.2 percent. Following is McKOOI et <br />. ales. (1987) LS equation: <br />13-3-9 Revised 08/11/92 <br />