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Table 4.4-1. Trapper Mine range sites estimated pre and postmine soil loss based <br />• upon lowest measured mean % cover, 1979-85, from premine areas. <br />A = RKLSCP <br />A = Soil loss,Tons/Acre/Year <br />R = Rainfall factor ... 30 <br />K = Soil erodibility factor. . . .25 (mine average) <br />LS = Slope - length factor ... 9.95 (Avg slope length, 1,500 ft) (Avg slope %, 14.7%) <br />C = Cover factor (a combination of % canopy cover and litter) <br />P = Conservation practice factor ... 1 for premine areas, .8 for postmine areas <br />(12.1 - 18% slope contour fanning). <br />Premine Range Site A Worst Year Recorded. 1979 <br />A = (30)(.25)(9.95)(.098)(1) = 7.3 Tons/A/Yr. <br />• .098 cover factor is based upon 23% herbaceous cover and 13.6% litter cover giving 36.6% effective <br />cover. <br />• • Attached Table 4.4-3, SCS Tech. Note 50 (1982) was used to generate the above factor for cover. <br />The value assumes that shrubs contribute a canopy cover of 50%, and the herbaceous type is (G). <br />Postmine Range Site A <br />A = (30)(.25)(9.95)(.065)(.8) = 3.9 Tons/A/Yr. <br />Standard: <br />33% herbaceous cover and 19% litter (1)(2) <br />• .065 cover factor is based upon 33% herbaceous cover and 19% litter cover giving 52% effective <br />cover. <br />• Attached Table 4.4-3, SCS Tech. Note 50 (1982) was used to generate the above factor for cover. <br />The value assumes that shrubs do not contribute canopy cover, and the herbaceous type is (G). <br />• Litter cover factor is .372 of the total effective cover based on 1979 and 1985 premined data, Range <br />Site A, Table 2. <br />cont. <br />• <br />4-103 <br />Revision: TR-7 f <br />Approved: 2119A9