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The sagebrush reference area is located less than one mile south of the New Hori?an #1 site and <br />immediately north of the New Horizon #2 site. Both the sagebrush reference area and the mine reclaimed <br />areas are relatively flat, are located at the same approximate elevation and received the same treatment <br />during the study year of I X99, This exercise will show that the reclaimed areas do not have mare <br />sediment erosion than the original undisturbed areas. The reclaimed vegetative community is a perennial <br />grass community with some fortis and shrubs in low percentages. <br />The Universal Soil Lass Equation was developed in 1?b5 by wischmeier and Smith using earlier <br />equations by Musgrave in 1947. The equation was modified in 193 to account for steeper slope areas, <br />change in erosion over time among other improvements. The revised equation (RUBLE) does account <br />for rill and inter-rill erosion.. lts complete form is listed below: <br />A=RxKx(LxS?xCxP <br />where: <br />A =soil lass in tonslyear per acre <br />R =rainfall factor from standard chart of area) <br />R =soil eradibility factor (function of site specific soil <br />LS =length slope factor (from contour map & chart.} <br />? =management factor dependent upon vegetation & mulch <br />P =erasion control practice factor <br />Rainfall factor "R" <br />The rainfall factor is the product of rainfall energy tunes the maximum ?o-minute intensity for a given <br />rainstorm. It is considered as the erosive power of the rain for that particular area, A chart of "R'" values <br />. far Colorado developed by the Transportation Research Board in 198o shows that the "R" value for the <br />entire Nucla area is Z?. <br />Since the reclaimed land slope is identical to the pre?mi?.e slopes but the manner in which settling of the <br />reclaimed surface may cause some ponding on the large flat areas, a lower rainfall factor could be <br />assumed for the reclaimed areas, however, this will not be done to be conservative in the estimate, <br />For a discussion of this adjustment to the rainfall factar, see Design Hydrology and Sedimentalogy of <br />Small Catchments by Haan, Barfield and Hayes. <br />Soil rodibilit? Factor ".?'? <br />This is a measure of the soil's susceptibility to erasion. Xt is dependent upon the soil's resistance to <br />detachment by rainfall and by its ability to absorb water through infiltration. <br />The soil erodibility factor "R'",was determined from consultation with the BCS Field 4f?ce in Norwood, <br />Colorado responsible far mapping and analysis of the regional soils. The reference area is comprised <br />entirely of Nyswonger silty clay loam with a "?„ of o.37.