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Mountain Coal Company <br />West Elk Mine <br />Post Olfice Box 591 <br />Somerset, Colorado 87434 <br />Telephone 970-929-5075 <br />February 16, 1998 <br />Mr. Michael Boulay <br />Colorado Division of Minerals and Geology <br />1313 Sherman Street, Room 215 <br />Denver. CO 80203 <br />RECEIVED <br />FEB 17 1998 <br />Division of Minerals & Geology <br />iii iiiiiiiiiiiiiii <br />.. <br />RE: Minor Revision No. 239 (Slope Stability Projects); West Elk Mine; <br />Permit No. C-80-007 <br />Dear Mike: <br />In Mountain Coal Company's (MCC) continuing efforts to control the slope stability <br />at the main mine facilities, a minor revision is requested to construct a large <br />subsurface drain system, which consists of french drains and an interception trench <br />to collect and channel shallow groundwater. The revision is requested because some <br />of the french drains will be constructed in areas previously undisturbed by mining <br />activities. Please find enclosed drawings, which show the location of these, french <br />drains and the interception trench. Please be aware that this system will be <br />constructed using an observational approach. As construction begins and more <br />information about local conditions is gathered, the plan as presented in this revision, <br />may change. For example, depth and alignment of the drains could change <br />depending on actual conditions. <br />The interception trench will be constructed in two phases. Phase 1 will be <br />constructed along the main mine access/haul road beginning at the employee parking <br />lot and ending at the light-use road to the substation. Phase 2 will continue down the <br />substation road and end near the northeast comer of the substation. The purpose of <br />the interception trench is to collect shallow groundwater near the head of the slide. <br />The depth of the interception trench may vary, but will be approximately 35-feet <br />deep. It will be backfilled with pea gravel and the down-gradient side of the trench <br />will be lined with a 30mi1 PVC liner. A 6-inch diameter perforated ADS pipe will be <br />placed near the bottom of the trench. The interception trench will drain into existing <br />surface drainage structures. As noted, the interception trench will be constructed in <br />previously disturbed areas (i.e. in the middle of the main mine access/haul road); <br />therefore, no topsoil will be stripped. Subsoil excavated will be placed in the Live <br />Subsoil Pile in Sylvester Gulch. The trench is intended to be long-term and will not <br />be removed upon final reclamation. <br />