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2.0 RUSLE COMPARISON <br />The USDA RUSLE method (Mays 2001; USDA b) is used in conducting this analysis. The soil loss in <br />tons/acre/year is expressed as follows: <br />A=RxKxLSxCxP <br />Where: <br />A =Soil loss in tons/acre/year <br />R =Rainfall or Erosion Index Factor <br />K =Soil Erodibility Factor <br />LS =Slope Length of Topographic Factor <br />C =Cropping Management Factor <br />P =Erosion Control Practice <br />The following sections detail the methods used in determining these inputs. <br />2.1 RAINFALL OR EROSION INDEX FACTOR (R) <br />The storm type for Colorado is SCS Type II, which has an associated R-factor of 10 (USDAa). <br />2.2 SOIL ERODIBILITY FACTOR (K) <br />The soil erodibility factor (K) can be determined from the soils texture content and percent of organic <br />matter. The field visit conducted in November of 2004 chazacterized the soil and organic matter content. <br />These results along with associated K factors are presented in Table 2-2. <br />TABLE 2-1 -SOIL ERODIBILITY FACTOR <br />Site Description Texture Class Organic Matter Content K Factor <br />SAES <br />Portal Dazk cla loam 4% or hi er 0.21 <br />To soil borrow area Dazk clay loam 4% or higher 0.21 <br />Development waster pile Dark loam to sandy loam 4% or higher 0.21 <br />Substation Dark loam to sand loam 4% or hi her 0.21 <br /> <br />UadisturbedArea Sandy loam 4% or higher 0.21 <br />Source: Mays 2UUI. <br />2.3 SLOPE LENGTH (LS) <br />The slope along with the slope length was determined using project maps and the November 2004 Feld <br />investigation report USDAb). Table 2-3 summarizes the results of this analysis. <br />210-RUSLE Rpt_Q O.18D5).doc 2-1 <br />