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Rannua( - 27P2,62.2 for a Type 11 storm <br />P2,6 = 2 year, 6 hour precipitation in inches <br />= 0.8 inches <br />R= 27 x (0.8)22 = 16.4 <br />2.2 SOIL ERODIBILITY (K) <br />The K factor represents the susceptibility of the soil material to erosion, transportility of the sediment, <br />and the amount of runoff given a particular rainfall input, as measured under stated conditions. For this <br />analysis, MW used the K value from the existing permit document. <br />K = 0.28 (clay loam) <br />2.3 LENGTH SLOPE FACTOR (LS) <br />The LS factor accounts for the effects of a hillslope length (L) and a hillslope-gradient (S). The <br />equation for determining the LS factor is: <br />For slopes < 9% <br />LS = (L172.6)'" x (10.8 x sin(S) + 0.03) <br />For slopes > 9% <br />LS = (L 172.6)"' x (16.8 x sin(S) + 0.5) <br />Where: L = Slope length <br />S = Slope angle <br />m = 0.3 for slopes< 3% <br />0.4 for slopes = 4% <br />0.5 for slopes > 5% and < 10% <br />0.6 for slopes> 10% <br />The slope length and slope angles for existing and reclaimed conditions are very similar, therefore the <br />LS factor for both is the same. The slope length and slope angles for both conditions were determined <br />from the Post Mine Topography Map ( Map 36) found in the existing permit. The LS calculations can <br />be found in Attachment 1, Calculation Spreadsheets. <br />2.4 COVER MANAGEMENT FACTOR (C) <br />The cover management factor represents the effects of vegetation, management, and erosion control <br />practices on soil loss. The C factors for pre- and post-mine conditions for the area were determined <br />using information from the vegetation study done by Kent Crofts (2009). The C factor of the different <br />vegetation types and cover is determined from Table 5.A.3 found in Applied Hydrology and <br />Sedimentology for Disturbed Areas (Barfield, Warner, and Haan, 1981). The values utilized are shown <br />in Table 1.