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West Elk Mine <br /> <br />2.05-108 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, 2/25-MR486 <br />landslides, including the landslides north and south of Minnesota Reservoir became unstable and <br />moved during the period of high precipitation in the mid 1980s. The landslides on the southeast <br />side of West Flatiron and on the west side of Deep Creek in the Apache Rocks area appear to have <br />been unaffected by longwall mining beneath the areas. It therefore appears apparent that wet <br />seasons affect landslides more than does longwall mining. During very wet periods, however, <br />landslides that are already unstable may locally be triggered by mine subsidence. The following <br />are known locations within the present permit area, the South of Divide and Dry Fork mining areas <br />where the reactivation of a landslide could occur as a result of future mining: <br />South of Divide mining area: <br />An extensive landslide located south of Minnesota Reservoir just north of projected Panels <br />LWE16 and LWE17 in the NW¼ of Section 32. <br />Dry Fork mining area: <br />There are three slides identified on the Deep Creek Ditch in Section 2, of Township 14 South, <br />Range 90 West, 6th P.M., one that warrants concern, this slide is located above the bleeder <br />entries along the south side of Panel E 6 the other two land slides are outside the influence of <br />mining. The slide will be monitored both visually and by survey methods. <br /> <br />A discussion regarding the monitoring plans for the landslide located on the south abutment of the <br />Monument Dam are included 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 <br />On Man-Made Structures And Renewable Resources”, Monument Dam - Minnesota Reservoir. A <br />discussion concerning the preventative measures to be employed to protect Monument Dam from <br />mining induced impacts is contained in Section 2.05.6(6)(f)(iv)(A-D) - Detailed Description of <br />Mitigating Measures. <br />Presently, there are four known locations within the permit area where the reactivation of a landslide <br />could be potentially linked to past or current mining. The first area, in Lone Pine Gulch (Section 20, <br />T13S, R90W, 6th P.M.), contains numerous old landslide features, including steep, hummocky <br />topography with many smaller surficial slumps. Cracking and slumping occurred on one section of <br />a jeep trail in this area in early October 1994. The cracks appeared during mining of the 5NW <br />longwall panel in the B-Seam. Location of the cracks coincides with the boundary of earlier F-Seam <br />room-and-pillar panels. The second area, discussed previously, is above the 8NW longwall panel. <br />This landslide activity, which could not be definitively linked to longwall mining, is described in <br />considerable detail in a CDRMS inspection report (CDRMS 1996). The third area is above the 9NW <br />longwall panel. Another known landslide area is south of Highway 133 near Box Canyon within the <br />Box Canyon Permit revision area. These landslides are outside the projected longwall mining <br />subsidence effects (i.e., 19 degree angle of draw) by more than 600 feet as described in Exhibit 60C, <br />60D and 60E. <br />Rockfall <br />The most current evaluations of subsidence impacts can be found in the quarterly subsidence <br />monitoring reports each year. In past years, as discussed in Section 2.04.6, Geology Description, <br />there are exposed rock faces on steep slopes where the potential for rockfall exists within the permit