2019-12-31_REVISION - C1981022 (15)

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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 revised to accommodate the increase in production. Continuous mining remained the mining method. With the approval of Technical Revision No. 29 (TR-29) on July 15, 1997, Oxbow Mining, Inc. (now Oxbow Mining, LLC.) began longwall mining. 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, TR-29 also approved Oxbow Mining, Inc.'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 TR-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 11 West Coal Refuse Facility in October 2003. On January 26, 1999, Oxbow Mining, Inc. 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 Division 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, Inc. to drill emergency boreholes into the mine, for water injection and for gas monitoring. In February of 1999, Oxbow Mining, Inc. pumped approximately 88 acre-feet of water from the North Fork of the Gunnison River through one of the emergency boreholes and into the Sanborn Creek Mine in the longwall area where the spontaneous combustion event was suspected. In April of 1999, Oxbow Mining, Inc. concluded that additional inflow was entering the mine workings and had the potential to flood the longwall equipment. The source of the additional inflow was not known and had an approximate inflow rate of 200 gpm. With the Division's approval, through Technical Revision No. 34 (TR-34), Oxbow Mining pumped out mine water to the North Fork of the Gunnison at a rate of about 2,000 gpm. The pumping occurred from July 1999 to the first week of October 1999. Oxbow Mining made a decision to dewater only half of the longwall panel in question and stabilize the water level in the mine thereafter. The longwall restarted operations at the beginning of November 1999. In anticipation of mining out the Sanborn Creek Mine B seam reserves, Oxbow Mining, Inc. submitted, on November 6, 1998, a revision to begin construction of the new Elk Creek Mine. Technical Revision No. 32 (TR-32) sought Division approval to construct the new portals and associated surface facilities, and to begin mining of private coal at the Elk Creek Mine. The construction proposed in TR-32 increased the disturbed area by 23.7 acres north of the main Sanborn Creek Mine facilities, along the west side of Elk Creek, and included two temporary fills over Elk Creek. Fill material was placed within the channel of Elk Creek and the creek flow was diverted through two nine-foot diameter culverts buried by the two fills. Oxbow Mining, Inc. submitted a geotechnical stability analysis demonstrating that the two fills in Elk Creek would be stable. The activities proposed in TR-32 required specific authorization by the 8