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West Elk Mine <br /> <br />2.05-109 Rev. 06/05- PR10, 03/06- PR10, 05/06- PR10, 11/060- TR107, 04/07- TR108, 09/07- PR12, 02/08- PR12; 11/10- MR372; 10/20- MR-452; <br /> 12/20- TR149; 12/21- TR150, 1/24-TR152 <br />there are exposed rock faces on steep slopes where the potential for rockfall exists within the permit <br />area. Theoretically, mining-induced changes in stress and strain and fracturing could trigger <br />additional rockfall from the many sandstone cliffs. <br />Predicted Subsidence-Related Phenomena and Material Damage Which Would Occur as a <br />Result of Subsidence - 2.05.6 (6)(b)(i)(B&C) <br />Predicted subsidence impacts for the mining area have been described in detail in the following <br />section entitled "Subsidence Prediction" 2.05.6 (6)(e)(i). Also refer to the most current versions of <br />Exhibit 60E and 55B. Given the magnitude of the subsidence projected in the above referenced <br />section, the following outlines the material damage which could result as a consequence of the <br />projected subsidence. Structures in the permit area are described in Section 2.05.6 (6)(a)(i & ii). <br />The discussions in Section 2.05-6(6)(e)(ii)(A-C) and Section 2.05.6(6)(f)(iv)(A-D) include the <br />"worse possible consequence" to these structures, as well as mitigation commitments. There is one <br />building in the South of Divide mining area and one outside the influence of mining in the Dry Fork <br />mining area. <br /> <br />There are a few USFS stock ponds within the SOD, Southern Panels, Dry Fork and Sunset Trail <br />mining areas. The stock pond embankments are not expected to be impacted, however, the ponds <br />will be monitored and any subsidence impacts mitigated by MCC per the USFS agreement letter in <br />Exhibit 19C. <br />The most significant surface impacts are expected to occur along the precipitous slopes and cliffs <br />immediately north of the Minnesota Reservoir and in those areas within the influence of longwall <br />mining. See the current Exhibit 60E for additional information on longwall panel cover depths and <br />the modeling results to project subsidence at varying mining heights and cover depths. <br />As discussed in Section 2.05.6(6)(e)(i) Potential Impacts from Local Seismic Activity, subsidence <br />could accelerate the naturally-occurring rockfall and landslide propensities that are already evident <br />in the permit area, but this will not constitute a hazard to either people or property nor would this <br />measurably impact the surface or ground water hydrology of the area. <br />Cracking of the earth along or across the trails or unimproved roads of the coal lease area already <br />naturally occurs, but in the "worse case" could be accelerated by, or additional cracks created by, <br />subsidence. As the trails and roads are unimproved, typically only all-terrain or four-wheel drive <br />vehicles are utilized and rough terrain is expected, so the hazards created by any additional <br />subsidence (rather than natural) cracking would be minimal. MCC will conduct visual inspections <br />of primary public access to the USFS lands on a monthly basis, weather and ground conditions <br />allowing, when these roads could be potentially impacted by undermining. MCC will mitigate all <br />roads that may have been impacted due to subsidence and provide signage, particularly on public <br />roads, warning of potential hazards. <br />Subsidence Prediction – 2.05.6 (6)(e)(i) <br />Brief Description of Mining Method - 2.05.6 (6)(e)(i)(A)