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Elk Creek Mine Soil Series and Complexes with Corresponding K Factor <br />Values for Reclaimed and Adjacent Undisturbed Areas <br />Map Unit Name <br />K <br />Source <br />Absarokee-Work loam (map unit 2) <br />0.32 <br />USDA, NRCS Web Site 7/22/2020 <br />Beenom-Absarokee Association <br />0.32 <br />USDA, NRCS Web Site 7/22/2020 <br />(map unit 13) <br />Delson Stony Loam, 3-20% slopes <br />0.15 <br />USDA, NRCS Web Site 7/22/2020 <br />(map unit 33) <br />Delson Stony Loam, 20-60% slopes <br />0.10 <br />USDA, NRCS Web Site 7/22/2020 <br />(map unit 34) <br />Cryochrepts-Cryoborolls-Rubble land <br />0.02 <br />USDA NRCS Web Site 7/22/2020 <br />complex (map unit 130) <br />Herm-Fughes-Kolob family complex <br />0.15 <br />USDA, NRCS Web Site 7/22/2020 <br />2.1.3 SLOPE ERODIBILITY FACTOR (LS) <br />The steepness of the slope and the length of the slope both affect the degree of soil <br />erosion on a given slope surface. The LS factor is a ratio of soil loss at any length <br />and slope to that of a standard empirical slope. In the instance of the Elk Creek <br />Mine site, the reclaimed and adjacent undisturbed slopes are of relatively uniform <br />slope for the areas of concern. In this case the LS factor can be calculated by the <br />following equation: <br />LS = (k / 72.6)m * (430x2 +30x + 0.43)/6.613 <br />where: <br />is slope length <br />x is sin 0 (where 0 is the angle of slope) <br />in is a slope dependent exponent (0.5 in our case) <br />During prior Phase II bond release reviews, CDRMS staff requested that the LS <br />factors for the sedimentology evaluation be derived from the nomograph contained <br />in Technical Note #51 from the USDA. The characteristics of the slopes at the Elk <br />Creek Mine within the reclaimed areas to be evaluated for release and adjacent <br />undisturbed extended reference area were derived from direct observations made <br />during the vegetation field study. Slope angles and overall slope lengths were <br />recorded and are presented on Table A., as are the derived LS factors for each area. <br />The LS factor values for the reclaimed and undisturbed areas were derived from <br />Table 3 in the successor document to Technical Note #51, Agricultural Handbook <br />No. 537 (Wishmeier and Smith, 1978). <br />............................................................................. <br />............................................................................. <br />Oxbow Mining, LLC Elk Creek Mine Page 4 <br />Phase 11 Bond Release Sedimentology Evaluation 2020 <br />