2024-03-12_REVISION - C1981022 (18)

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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 Division in accordance with Rule 4.05.4(4), Stream Channel Diversions (Relocation of Streams) and Stream Channel Reconstruction, and Rule 4.05.18, Stream Buffer Zones. Therefore, the Division made the finding that the original stream channel will be reconstructed at the completion of mining, the water quantity and quality from the stream section within 100 feet of the surface coal mining operations will not be adversely affected during and after mining, and that appropriate riparian vegetation will be reestablished. TR-32 was approved in July 2000. Permit Revision No. 5 (PR-5)required a mine plan approval from the US Office of Surface Mining and Reclamation (OSM), to cover activities in the Elk Creek tract which was received on May 13, 2003. This Elk Creek operation ramped down from the floor of the Elk Creek Canyon into the D-seam. Development mining had already been approved at the time of the PR-5; longwall mining into the Elk Creek tract was approved by the revision and by the federal mine plan approval. Mining ceased in the Sanborn Creek Mine in the spring of 2003. Oxbow Mining, Inc. began immediately to reclaim the Sanborn Creek facilities. The conveyer was dismantled and removed in the summer of 2003, the portals were sealed and regraded, and the Sanborn Creek fan shaft was backfilled. In January 2013, the Elk Creek Mine was evacuated due to the detection of gasses which indicated a heating activity behind the longwall operation. Inert gasses were injected into the mine workings behind temporary mine seals to extinguish the heating event. During this time, all mine dewater pumps were shut down for safety reasons. Water continued to accumulate in the workings until it reached a level that prevented proper ventilation and longwall recovery efforts. Two mine dewatering wells were approved with Minor Revision No.'s 104 and 105 (MR-104 and MR-105)to pump out the mine workings. Shortly after the mine was re-entered in August 2013, mine gas monitoring indicated that the heating event was not extinguished and had re-ignited. The mine was then re-sealed, and the longwall mining equipment was abandoned in panel 18. In August 2015, OMLLC submitted Technical Revision No. 76 (TR-76)to revise the post- mining land use and post-mining topography at several locations within the mine's disturbed area. TR-76 allowed for development of the methane resource in the sealed mine workings, on 9