2009-02-09_REVISION - C1981022 (2)

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C-1981-022 RN-05 Findings February 2009 The Sanborn Creek addition to the Somerset Mine, now the Sanborn Creek and Elk Creek Mines, is located approximately one mile east of the town of Somerset. Initially, this part of the mine was developed and mined using conventional room and pillar techniques with the same conventional equipment as previously discussed, except that conveyors were used in place of rail cars. Annual production of this part of the mine was projected to be about 750,000 tons per year. Upon opening the portals, coal was first trucked to the tipple at the Elk Creek yard. A conveyor system was built while developing the first part of the Sanborn Creek addition. The conveyor system was used instead of haul trucks to convey coal from the Sanborn Creek portals to the tipple at the Elk Creek yard. The Sanborn Creek East Tract and the East Tract modification, are located adjacent to the original Sanborn Creek addition on the eastern boundary and is an underground continuation of the Sanborn workings. No additional surface disturbance was required. Method of operations and production rate projections remained the same. With the approval of Technical Revision No. 24 on February 15, 1995, the coal production level at the mine was increased to 1.3 million tons per year. The production level at the loadout was increased to 1.6 million tons per year. The mine plan was also changed to accommodate the increase in production. Continuous mining was still the mining method used. With the approval of Technical Revision No. 29 on July 15, 1997, Oxbow Mining, Inc started the longwall mining method. The anticipated annual coal production was increased from 1.3 million tons per year to 4 million tons per year. To handle this increase in production, this revision also approved Oxbow Mining's plans to improve the coal handling facilities, increase the coal stockpile size, construct a new coal waste disposal site, move existing or build new support facilities and modify the train loadout for the new production rate. The West Valley Fill coal refuse area was permitted through Technical Revision No. 29 for use when the East Yard waste pile was filled to capacity. The operator began using the West Valley Fill coal refuse area during the third quarter of 2000. TR-43 approved the new Il West Coal Refuse Facility in October 2003. On January 26, 1999, Oxbow Mining evacuated the Sanborn Creek Mine due to elevated levels of carbon monoxide. The concern was that the elevated levels may have indicated a mine fire. The Mine Safety and Health Administration (MSHA) and the DMG were notified. Emergency measures were taken to seal the mine openings. Two days after the sealing of the mine openings, there was an explosion in the mine, presumably due to a buildup of methane. MSHA directed Oxbow Mining to drill emergency boreholes into the mine, for water injection and for gas monitoring. In February of 1999, Oxbow Mining pumped about 88 acre-feet of water from the North Fork of the Gunnison River through one of the emergency boreholes, into the Sanborn Creek Mine in the longwall area where the spontaneous combustion event was suspected of being located. In April of 1999, Oxbow Mining concluded that additional inflow was coming into the mine and might flood the longwall equipment. The source of the additional inflow was not known but the 9