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`-MOUNTAIN COAL <br />~-~`' \~~`COMPANVL.L.C. <br />A Subsidiary of Arch Wes~enr Resources, LLC <br />April 11, 2002 <br />Mr. James Burnell <br />Colorado Division of Minerals and Geology <br />Office of Mined Land Reclamation <br />1313 Sherman Street, Room 215 <br />Denver, Colorado 80203 <br />RECEIVE® <br />AP? ? 2 2002 <br />Uivisian of Minerals and Geology <br />West Elk Mine <br />POBox 591 <br />5174 Highway 133 <br />Somerset, CO 81434 <br />(970)929-5015 <br />Fax (970) 929-5595 <br />Re: Mountain Coal Company LLC (MCC), West Elk Mine; Permit No. C-80-007; Technical <br />Revision No. 92, Small Area Exemptions for the Raw Water Intake Gallery and Sylvester <br />Gulch F-Seam Fan Facility, Adequacy Responses. <br />Dear Mr. Burnell, <br />Mountain Coal Company, L.L.C. is submitting these adequacy responses to the Division's letter dated <br />April 26, 2001. The technical revision is to include Small Area Exemptions (SAE) for the Raw Water <br />Intake Gallery and the Sylvester Gulch F-Seam Fan Facility. The delay between the Adequacy Letter <br />and MCC's responses is due to a change in consultants. The original consultant no longer had the <br />capability to run SedCad after the original submittal by MCC to the Division. Therefore, a new <br />consultant was selected by MCC to complete what others had begun. <br />Included with this submittal are the SEDCAD reruns, sketches of the SAES and revised maps 54, 54A, <br />and 54B. We believe the following responses are adequate after all of our discussions with CDMG <br />personnel. CDMG's numbered questions and comments, from the 26 April 2001, letter, are listed <br />below with MCC's responses in bold text. <br />1. For the raw water intake gallery SAE, please provide the input values to the RUSLE version <br />1.06 modeling program for the K value of 0.08 and the C value of 0.0024. <br />SEDCAD analyses were rerun using a K value of 0.20 and a C value of 0.20. The K factor <br />of 0.20 was calculated using a spreadsheet function based on the soil erodibility <br />nomograph of Wishmeier et al. Particle size distribution selected for the function is <br />typical of sandy clay looms, which forms the surface layer of the soil. The rock fragment <br />content exceeds 35 percent. Organic content of the soil is low, an estimated 1 percent: <br />Permeability is rapid to moderately slow. The K value represents a median value <br />representing slow to moderate permeability. <br />A C factor of 0.20 was selected to represent cover at the surface at the raw water intake <br />gallery. The procedure for determining the C factor was taken from the NRCS Technical <br />Release 51. The vegetation cover consists of sparse grass with no appreciable canopy, and <br />no more than 20 percent cover. <br />