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West Elk Mine <br />• Finally, MCC will be installing several seismic monitoring stations in the pemut area, including the <br />SOD area, to obtain data regazding mining-induced microseismicity and naturally occurring seismicity. <br />This monitoring system will be used to determine if a significant ground acceleration event has <br />occurred in the Monument Dam area and will trigger additional monitoring and responses from MCC <br />to ensure the safety of the dam and the people living and working downstream of the dam. The <br />monitoring program is described in Section 2.05.6 (6)(e)(i)(D) -Detailed Description of Predicted <br />Subsidence Phenomena, Subsection "Effects Of Subsidence And Mine-Induced Seismic Activity On <br />Man-Made Structures And Renewable Resources", Monument Dam -Minnesota Reservoir. <br />MCC will be participating in modifying the Monument Dam to ensure material damage does not occur <br />to the structure as aresult ofmining-induced microseismicity and to increase the factor of safety to 1.5, <br />(See Section Detailed Description of Mitigating Measures - 2.05.6(6)(f)(iv)(A-D)). The survey and <br />seismic monitoring programs will be implemented prior to mining related subsidence beginning in the <br />SOD to establish a baseline data set. Further, the programs will be used to determine if mining related <br />activities are causing mitigatable damage to the dam structure. For example, the monitoring plans call <br />for establishing a peak ground acceleration (pga) threshold value the modified dam can withstand. If a <br />seismic event occurs generating acceleration values at or above the threshold, MCC will inspect the <br />dam and related structures for damage. Additionally, the monuments in and around the dam and <br />landslide will be surveyed to establish if movement occurred as a result of the event. If significant <br />damage has occurred, a notification plan will be implemented as described in Section 2.05.6 <br />(6)(e)(i)(D). <br />After the notification, it will be determined whether or not the event was naturally occurring or mine- <br />generated. If mining related damage occurs, MCC will implement the appropriate mitigation plan as <br />described in later sections of the document. Regazdless of the reasons for the damage, whether <br />naturally occurring or mine-induced, if it is appazent significant damage is imminent or human life is in <br />danger, all necessary precautions and actions will be immediately implemented by MCC to lessen or <br />eliminate the threat. The local authorities, including the Paonia Fire Department, law enforcement <br />agencies, CDMG Permit supervisor and inspector assigned to the West Ells Mine, District Forest <br />Ranger, and the President or authorized representative of the Minnesota Ditch and Reservoir Company, <br />will be notified of the potential threat as soon as possible. <br />Description of Possible Subsidence Consequences - 2.05.6(6)(6)(7) <br />Pre- and Post-mining Land Uses -2.05.6 (6)(b)(i)(A) <br />As indicated in the Mountain Coal Company Coal Methane Drainage Project EA {February 2002), <br />North Fork Coal EIS (2000), and Environmental Analysis U-94-37 (November 1994), prepazed by <br />the U.S. Forest Service (USFS) and U.S. Bureau of Land Management (BLM), in cooperation with <br />the U.S. Office of Surface Mining (OSM) and other jurisdictional agencies, the permit azea lands <br />support wildlife use, dispersed recreation, and livestock grazing. <br />The Forest Service Amended Land Resource Management Plan prescribed land use designations of the <br />Box Canyon lease tract, South of Divide permit revision area, and surrounding USFS lands as "SA", <br />"6B," and "9A" which emphasize riparian, wildlife habitat, and livestock grazing, respectively, <br />1.05-/09 Revised June 2005 PR/0, Rev. March 2006; Rev. Apri12006 PRI G; May 2006 PR70 <br />