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III Illllllllllllllf'f 999 Mountain Coal Company West Elk Mine Post Office Box 591 Somerset, Colorado 91434 Telephone 970-929-5015 February 27, 1998 Mr. Michael Boulay Colorado Division of Minerals and Geology 1313 Sherman Street, Room 215 Denver, CO 80203 RE: Minor Revision No. 239 (Slope Stability Project); West Elk Mine; Permit No. C-80-007 Dear Mike: Mountain Coal Company (MCC) has reviewed the adequacy comments presented in a letter dated February 24, 1997, regarding the above referenced minor revision and provides the following additional information. MCC cannot predict the volume of water that will discharge from the drain system. Based on experience from other french drains that have been installed around the mine site, the volume of water will be small and most likely seasonal. Water from the drains will flow into ditch Dl-4, culvert C1-6, ditch D]-3, and into MB-1. The minimum design requirements for each structure are presented in Table 44. Afield check of the existing structure was conducted. The following table compares the minimum design to the actual constructed structure. DESIGN ACTUAL STRUCTURE DISCHARGE MIN. DEPTH OR DIA. SHAPE DEPTH OR DIA. SHAPE WIDTH (TOP D1-4 2.06 cfs 0.71 ft. (8.5") V 22 in. 3' Tra 10 ft. C 1-6 2.06 cfs 12-inches CMP 51-in. x 30- in. Arch CMP NA DI-3 6.55 cfs 1.04 ft 12.E") V 27 in. 3' Tra 10 ft. As you can see from the table, the actual constructed ditches and the culvert far exceed the minimum design requirement. And with the minimal, seasonal flow expected from the drains, the ditches, culvert and pond are more than adequately sized to accommodate the flow. RECEIVED i 1, ... ~..~ L,Lt~ Division of Minerals & Geology Upon final reclamation, the french drains will be extended to discharge into the stone columns. The ditches and the culvert in this area will be obliterated by the final reclamation grading as currently approved in MCC's reclamation plan.