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pQabOdy Twentymile Coal Company August 29, Zoos Mr. Byron Walker Environmental Protection Specialist Colorado Division of Minerals and Geology 1313 Sherman Street, Room 215 Denver, Colorado 80203 (303)866-4941 RECEIVED AUG 3 0 2005 Division of tdinerals and Geology 29515 Routt County Road #27 Oak Creek, CO 80467 970.879.3800 RE: Twentymile Coal Company - Foidel Creek Mine (Permit No. C-82-056), Minor Revision (MROS-198) for 6-North Mains Power-Drop Rock Dust, and Water Boreholes Dear Mr. Walker: Twentymile Coal Company (TCC) is requesting approval of a Minor Revision to the approved Permit to complete five utility boreholes in the 6-North Mains Ventilation Shaft facilities area. As we previously discussed, TCC has previously submitted and approvals are currently pending for Technical Revision TROS-48 for the 6-North Mains Shafr facilities and associated ancillary structures (including the utility boreholes). Given that final review of the TROS-48 submittal and resolution of any questions may take additional time plus the required 10-day public comment period for the proposed decision, TCC is submitting this Minor Revision application with the intent of addressing a practical time constraint and expediting required site work. We are facing a practical field constraint for completion of the utility boreholes (specifically the power-drop boreholes) relating to the minimum temperatures under which the manufacturer will honor the power cable casing warrantee during cable placement operations. In simple terms, it is starting to get cooler during the night and early moming/evening hours, and if we wait much longer to install the power cable, we may have problems with both installation and warrantee. We have only become aware of this constraint recently, when we contacted the vendor about supplying the cable. The requested minor revision involves eazly initiation of the utility borehole construction activities addressed under TROS-48. We propose to complete temporary drainage structure placement (silt fence and wattles), topsoil stripping, and drill pad and mud pit construction for a small drill pad (200 x 200 feet) within the footprint of much larger 6- North Mains Shaft Pad. Under current site conditions, road construction would not be required for a borehole rig to access the site. Once the pad and incised mud pit are completed, the borehole drill rig would complete and case five 13-inch (nominal diameter) boreholes to the level of the coal seam (approximately 1,300 foot depth). If the incised mud pit is not adequate to totally contain all cuttings and drilling fluids, porta-pits (skid-mounted steel tanks) would be utilized or excess fluids and cuttings would be pumped to a truck for transport to the existing 18-Right cuttings pit. On completion of drilling and casing operations, it is reasonably anticipated that approvals will be in-place for TROS- 48, and the proposed larger-scale pad construction activities could proceed. The temporary mud pit for the utility borehole drilling opemtions would be drained or allowed to dry-out (dependent on the amount of fluids retained), backfilled, and compacted. All disturbance associated with the utility borehole drilling operations would be incorporated into the lazger 6-North Mains Shaft Pad azea. I have attached the required revision form and copies of relevant revised pages. We appreciate your consideration and cooperation. Once you have had opportunity to review the accompanying information, please feel free to contact me with any questions or to discuss related matters. G:\Environmental\REVISION\MINOR-RV\MR05-198 6NM Powerdrop Boreholes\MR05-198 Letter of 1Yansmittal.doc