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MOUNTAIN COAL <br />VCOMPANVL.L.e. <br />A Subsidiary of Arch Western Resou¢es, LLC <br />Apri13, 2002 <br />Mr. James Burnell <br />Colorado Division of Minerals and Geology (CDMG) <br />Office of Mined Land Reclamation <br />1313 Sherman Street, Room 215 <br />Denver, Colorado 80203 <br />~~~~°~~® <br />pivls\oo 05 Mt^ata\s aad Sao\o0V <br />PPR ~ ~ 2r~12 <br />West Elk Mine <br />P.O. Box 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; Minor <br />Revision No. 286, Sediment Trap Installation. <br />Dear Mr. Burnell: <br />MCC is requesting a minor revision to the mining and reclamation permit to construct a sediment trap <br />neaz the Raw Water Intake Gallery (RWIG). Referring to the attached drawings, the sediment trap will <br />be constructed to collect sediment-laden water from a cyclone type liquid/solids separator that will be <br />installed in the RWIG. The sepazator will dischazge sediment-laden water from the RWIG to the <br />sediment trap at a rate of up to 10 gpm during seasonal high runoff from the North Fork of the <br />Gunnison River, The separator is apre-treatment of raw water from the RWIG prior to pumping the <br />water to the Freshwater No. 1 Pond (FW-1). Pre-treatment of raw water, specifically for total <br />suspended solids, is advantageous to MCC during high runoff to improve the quality of water used in <br />the mine and for potable water treatment purposes. It is planned that the separator will not be in use <br />when the river is not turbid or when FW-1 is full. <br />The 9,400 gallon sediment trap is designed for clean-out by back-hoe or loader. The sediment will <br />then be deposited on the RPE as necessary. The project location is within the current disturbed azea <br />and will be located approximately 50 feet southwest of the RWIG. <br />Discharge water from the sediment trap will be conveyed to the D3-1 ditch and flow to an existing <br />sediment trap prior to flowing into sediment pond MB-3. It is anticipated that the alignment of the D3- <br />1 ditch will not change. Because the dischazge is periodic and less than the amount of water used <br />during "wash-downs" of the silos, the volume capacities of the D3-1 ditch and MB-3 are sufficient for <br />this very low rate of flow. <br />MCC would appreciate the Division's calculation of the bond estimate for this project. <br />