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Seneca Coal Company will periodically monitor the sediment storage capacity to ensure <br />enough capacity is available. The estimated design storm sediment volume is based on a <br />worst-case disturbance Sn the watershed. This worst case will not occur until <br />approximately 1998. Therefore the constructed sediment storage capacity should be <br />adequate for at least three years. <br />Particle Size Distributions. The particle size dlst ributlon for [his sedimentation pond <br />was based on sieve and hyd rome[er anal ysSs of various soil types in~the Yoast permit area. <br />This distribution Ss rep resentatlve of the watershed for Pond 010 and based on a weighted <br />average. The specific gravity and the submerged bulk sped f1c gravit }~ of the soil are <br />estimated to be 2.50 and 1.17, respectively. <br />Particle SSZe Distribution lsl <br />Weighted Average <br />NAT1 SPL2 <br />Size Imm1 0 Finer a E1 ner <br />12,7000 100.00 lOD <br />11.2000 96.00 99.9 <br />2.0000 86.00 99 <br />1 <br />0000 83 <br />00 91 <br />. <br />. <br />0.5000 81.00 87 <br />0.2500 80.00 84 <br />0.1060 75.00 BO <br />0.0450 41.00 58 <br />0.0200 20.00 46 <br />0.0100 12.00 3B <br />0.0050 8.00 28 <br />0.0020 7.00 18 <br />D.0010 4.00 14 <br />0.0001 0.00 0 <br />Length-Slope Factor ILS1. The lengthslope Ss described as the typical length-slope for <br />the subwatersh etl and the distance from the point of eri gin of overland flow to a point <br />where the slope decreases such that significant deposition occurs or until the flow enters <br />a defined channel. The length-slope for watersheds above Pond 010 was determined to be <br />between 100 and400 feet, and the average slope was determined to be approximately 15.0 <br />percent. Fo 11ow1ng is McKool et al's. 11987) LS equation: <br />13-3A-6 Revised 08/30/96 <br />