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2008-05-08_PERMIT FILE - C1981018A (3)
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2008-05-08_PERMIT FILE - C1981018A (3)
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Last modified
8/24/2016 3:31:14 PM
Creation date
6/19/2008 1:26:10 PM
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Template:
DRMS Permit Index
Permit No
C1981018A
IBM Index Class Name
Permit File
Doc Date
5/8/2008
Section_Exhibit Name
Section V. Mine Surface Facilities Reclamation Plan
Media Type
D
Archive
Yes
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• C =Crop management factor <br />P =Control practice factor <br />The rainfall factor (R) used for the Deserado Mine was 30 which was obtained from Figure 1, <br />EPA-908, "Average Annual Value of Factor R." <br />The soil erodibility factor (K) was taken from the SCS area soils survey. Where K factors were not <br />available, a suitable value was obtained by using the material characteristics and using Figure 3, <br />EPA-908, "Nomograph for Determining Soil Erodibility - Factor "K" or from Appendix A Factors "K" <br />and "T". EPA-908. <br />The length-slope factor (LS) was determined by measuring sub-area lengths and slope <br />percentages on a map of the drainage basins. The lengths and slopes were then used to obtain <br />the (LS) factors from Table 1 in EPA-908, "Values of the Topographic Factor'LS"'. <br />The crop management factor (C) and the control practice factor (P) were assigned the value of 1.0 <br />for disturbed areas. This value corresponds to freshly denuded sites with no conservation <br />practices. Undisturbed areas were assigned values for (C) and (P) in accordance with their existing <br />vegetative cover from Table 4, EPA-908, "'C" Factors for Permanent Pasture and Rangeland" and <br />Table 6, EPA-908, "Determining Factor 'P"." The percentages of vegetative cover were taken from <br />• Section II-F, Vegetation Report. <br />Multiplying the factors R, K, LS, C and P yield the annual sediment yield A in tons per acre. <br />Multiplying A by the acres in the subarea (Ar) yields the annual sediment yield in tons. <br />A bulk density of 80 pounds per cubic foot was assumed for the settled solids. The estimated bulk <br />density was based on the formula d = We Pc + Wm Pm + Ws Ps where: <br />d = dry unit weight in pounds per cubic foot <br />Pc,Pm,Ps = percentages of clay, silt, and sand, respectively <br />Wc,Wm,Ws = coefficients for clay, silt, and sand, respectively <br />The above formula and coefficients were taken from "Design of Small Dams," Bureau of <br />Reclamation, 1974, pp. 778 and 779. The average percentages of clay, silt and sand for the project <br />area were estimated by a qualified geotechnical engineer during the field investigation for the soils <br />and foundation investigation for the project plant facilities. <br />The coefficients and percentages used were as follows: <br />Pc = 10 percent Pm = 50 percent Ps = 40 percent <br />We = 40 percent Wm = 72 percent Ws = 97 percent <br />d = 40 x.10 + 72 x .50 + 97 x.40 = 78.8 <br />• <br />Mid-Term Review 2002 (812002) V-9
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