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TO: Diane Delaney <br />FROM: D : • ' i <br />�_ _ 1 S orTi,Ps <br />RE: Small area exemptions <br />DATE: 7/16/91 <br />Small Area Exemptions <br />TR -20 10/91 <br />Page # Revised <br />MR -36 5/92 <br />•'1 ;.�:U tl . 7 -1N C.; <br />The information you requested on the various small areas is <br />complete and is contained herein. <br />Soil loss for each area in question has been calculated using the <br />universal soil loss equation. <br />A = RKLSCP <br />A = SOIL LOSS (TONS /ACRE /YEAR) <br />R = RAINFALL AND RUNOFF FACTOR <br />K = SOIL ERODIBILITY FACTOR <br />LS = SLOPE LENGTH AND STEEPNESS FACTOR <br />C = COVER AND MANAGEMENT FACTOR <br />P = EROSION CONTROL PRACTICE FACTOR <br />The vague for R at Coal Basin determined from U.S. Weather <br />Service table and adjusted for snow melt runoff is 40. <br />For conservatism a maximum value of .37 for K is used except <br />where data for calculating K values is available. <br />The cover varies from site to site values C factors were <br />determined from the table for permanent pasture and rangeland for <br />western colorado. <br />A maximum factor of P = 1 was used for conservatism. <br />The LS values were determined from measured survey values and a <br />table for LS factors. <br />A sketch of each area is included which lists area, LS value, C <br />value, and K factor used in determining the amount of soil lost. <br />A table is also included which shows the values of the universal <br />soil loss equation and the resultant soil lost each year. <br />Assumeing a denisty of 70 lbs /cubic foot a volume has also been <br />provided. <br />57 <br />