Laserfiche WebLink
Computer Modeling Program developed by Civil Software Design. The SEDCAD4 Computer model is <br />based on the Revised Universal Soil Loss Equation (RUSLE). The input parameters used in the <br />sedimentation analyses are presented in the following sections. <br />2.1 RAINFALL FACTOR, R <br />A rainfall factor of 19 was used for the Colowyo mine site. This factor is consistent with other recent <br />erosion analyses performed for the Colowyo Coal Company. <br />2.2 SOIL ERODIBILITY FACTOR, K <br />The soil erodibility factors for the Colowyo Mine were estimated based on soil survey information <br />presented in the Colowyo Permit Application. Note that for historic (existing) designs, an average of 0.28 <br />was used for K. Future designs will be based on a K value of 0.30. <br />TABLE2 <br />SOIL ERODIBILITY FACTOR <br />DOMINANT SOIL TYPE SOIL TEXTURE SOIL ERODIBILITY <br />FACTOR (K) <br />Burnette Series Loam 0.28 <br />Work Series Loam 0.31 <br />Average 0.30 <br />2.3 LENGTH-SLOPE FACTOR, LS <br />Input parameters to determine the LS factor were obtained from scaled maps of the watershed areas. <br />Values measured from the scaled maps are shown in the SEDCAD4 printouts. <br />Exhibit 7 Page 4 Revision Date: 6/19/09 <br />Revision No.: TR-73