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Mountain Coal Company West Elk Mine Post Office Box 591 Somerset, Colorado 87434 Telephone 970.92&5075 November 5, 1997 Mr. Michael Boulay Colorado Division of Minerals and Geology 1313 Sherman Street, Room 215 Denver, CO 80203 R€E€I~rFn NOV ~ A 1~~1 (a1fJf1{I~()191 MIRBfn+a ~ err :~df -ii -ii-iiiii-iii-ii ~~ RE: Minor Revision No. 231 (Slope Stability Projects); West Elk Mine; Permit No. C-80-007 Dear Mike: Mountain Coal Company (MCC) requests a minor revision to update MCC's bond liability cost estimate to include the emergency slope stability projects that were completed this spring and summer or will be completed in the near future. Some of these projects were made known to the Division in a letter dated May 1, 1997. The projects included in this revision application are: replacing underground drainage control CMPs with surface HDPE pipe; replacing the underground raw water line with surface HDPE pipe; installation of piezometers; installation of inclinometers; reestablishing the stacktubes haul access road on the enlarged RCC buttress; drilling boreholes in the meadow above the portals, two additional pumping wells, and soil sample holes. A detailed description of each project follows. Underground Sediment Control CMPs Replaced with Surface Pike Culverts C1-1, C1-2 and C1-2A have been replaced with 24-inch I-IDPE pipe laid on the ground surface from an area above the portals to MB-1. The underground culverts had been in existence since the mine was constructed and have deteriorated. With the slope movement in this area, some of these culverts have also pulled apart in a number of places and have required numerous past repairs. Rather than replace or repair the culverts in the ground and continue to risk that they may pull apart and contribute unnecessary water to these already unstable slopes, MCC opted to construct the pipes on the surface. If leaks or breaks occur in these surface pipes, they would be visible and accessible for immediate repair. MCC has utilized I-IDPE pipe which is somewhat flexible and very durable. The pipe has been buried in the two locations where it crosses roads and for approximately 25 feet above MB-1. The existing culverts (Cl-l, C1-2, and Cl-2A) have been removed or filled with flow-fill (low compressive strength concrete) in areas where they are too deep, dangerous and difficult to remove.