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APPENDIX 2.05.3-7 <br />• IMPOUNDMENT SEDIMENT ANALYSIS <br />SUN COAL COMPANY - MEADOWS N0. I <br />ROUTT COUNTY, COLORADO <br />To calculate the sediment anticipated to accumulate in the temporary sur- <br />face impoundments, the Universal Soil Loss Equation (USLE) was utilized. <br />The USLE takes the form of A = RKLSCP <br />where A is sediment in tons/acres/year <br />R is the rainfall energy <br />K is the soil erodibility <br />LS is the slope percentage and slope ]ength <br />C is the cover afforded by vegetation <br />P is a practice factor used where agricultural cropping approaches <br />are used. <br />These are discussed in detail in numerous publications, especially <br />• Wischmier and Smith (1976) and EPA (1977). <br />For the mine area, a generalized "worst-case" approach was used. This <br />reflects the general uniformity of replaced topsoil and overburden. The soil <br />erodibility factor, K, was developed specifically for the site to reflect the <br />organic rich loam and silt loam character of the topsoil to be used in reclama- <br />tion and the low permeability characteristics of the regraded overburden. The <br />LS factor assumed a 3:1 slope, which is the limit of the recommended allowable <br />slope for the reclaimed surface; and a slope length of 200 feet, the maximum <br />slope length generally recognized as valid by the developers of the model (G. R. <br />Foster, personal communication). The R-factor is that identified by EPA (1977) <br />for the mine area. <br />• <br />- 255 - (Rev. 5/86) <br />