2010-06-01_REVISION - C1981019 (8)

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The Soil Survey of Moffat County Area, Colorado shows the following 9 mapped soils in the pre-mining footprint of the 28 Reclamation Units in this bond release submittal. Corresponding K values from the referenced soil survey are also provided. Unit Designation Soil Unit name K 25 Campspass fine sandy loam, 3 - 12% slopes 0.24 26 Campspass fine sandy loam, 12 -25% slopes 0.24 37 Cochetopa loam, 12 - 25% slopes 0.20 38 Cocheto a loam, 25 - 65% slopes 0.20 108 Jer -Cocheto a complex, 5 - 35% slopes 0.20 134 Morapos loam, 3 - 12% slopes 0.24 135 Mora os loam, 12 - 25% slopes 0.24 197 Torriorthents-Rock outcrop sandstone complex, 25 - 75% slopes 0.15 206 Ustortnents, Frigid-Burolls Complex. 25 - 75% slopes 0.24 The surface areas associated with the above described soils in the pre-mining soil survey were superimposed onto the 28 Reclamation Units maps. Weighted i average "K" factors were then determined for each Reclamation Unit, as presented in Table 4. For the reclaimed post-mining condition, it has been assumed that all of the topsoil will be randomly mixed when re-spread onto the final graded mine area. The overall weighted average across all 28 Reclamation Units was therefore used for the reclaimed post-mining condition. A weighted average value of 0.231 was calculated via this approach. Length Slope Factor, LS The areas of each of the 28 Reclamation Units were superimposed onto pre- mining and post-mining topographic maps. Representative slope lines were then draped onto the topography, using methods as described in Barfield, Warner and Haan 1981 and USDA 1996. At least one such line was selected for each Reclamation Unit for the pre-mining and post-mining condition, and the LS factor was determined according to the original SCS 1977 equation, which appears as Fig. 5.15 in Barfield. Warner and Haan 1981. Some Reclamation Units required more than one line due to differing topographic conditions. In these cases, the average of the several LS factors for each such Reclamation Unit was used. Pre-mining and post-mining LS factors are presented in Table 4. Phase I and 11 Bond Release Application 15