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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 farming). <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 /> 4-103 <br /> Revision: T_P-___ _— <br /> Approved: <br />