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Subsidence Evaluation for the <br />Exhibit 60E Southern Panels, Apache Rocks West, & Sunset Trail Mining Areas Page 33 <br />area too remote for any access roads or manmade features. Following mining in these <br />longwall panels, no additional rockfall was observed during semi-annual field studies. <br />9. This area is located on the eastern boundary of the Deep Creek watershed. This rockfall <br />area would have been over the eastern ends of panels E3, E4, and E5 if mined to the <br />maximum projected potential extent. However, based on where mining stopped in these <br />panels, the rockfall areas were outside the influence of mining. <br />Of the areas listed above, most occur near local drill roads or agricultural access roads, which have <br />only local, limited traffic on them. Any rocks that may fall in these areas could be readily removed <br />before local traffic is impacted, should rockfalls occur on these remote roads. Evidence of <br />naturally occurring rockfalls, such as remnant boulders located at the base of steep slopes, or in <br />the run -out zones of these areas, and documentation of these areas prior to mining is recommended. <br />Based on semi-annual observations in the Apache Rocks, Box Canyon, and Southern Panels <br />mining areas, subsidence and any seismic activity caused by longwall mining is not expected to <br />significantly affect rockfall areas with an estimated high to low rockfall potential. Only rockfall <br />areas with an estimated very high rockfall potential were noticeably affected. However, because <br />there are no rockfall areas with an estimated very high rockfall potential in the Southern Panels <br />mining area, the planned longwall panels in these mining areas will most likely not affect rockfall <br />areas. In the Sunset Trail mining area, the identified rockfall areas shown on Map 1 are all outside <br />of the projected mining influence. <br />10.3 Importance of Baseline Landslide and Rockfall Data <br />The most significant landslide in the Southern Panels mining area, in terms of proximity to man- <br />made structures, is located above the northern part of E -seam longwall panel E9 (Map 1). <br />Although there is a large landslide within the area of mining influence of the southeast corner of <br />E -seam longwall panel E8 (mostly in the NE'/4 of Section 8), the landslides located north and south <br />of Minnesota Reservoir are the most important in the mining area. Existing, natural (baseline) <br />conditions are monitored before mining begins in order to document their natural state. The cracks, <br />bulges, and depressions observed in the landslide areas north and south of Minnesota Reservoir <br />are much more extensive and dramatic than those caused by subsidence. The vertical aerial <br />photographs obtained by the West Elk Mine (dated July 2, 2004) provide good baseline images of <br />all the natural, pre -mine features in the Southern Panels mining area. <br />Observations made by WWE in the area of the West Elk Mine indicate that mining may accelerate <br />the natural landslide process, where there are landslides that have already become unstable. <br />However, annual observations of the surface cracks and depressions in the landslide area on Jumbo <br />Mountain above mined B -seam longwall panels 8 and 9 determined that landslides are very likely <br />only related to natural mass -gravity movements and not related to mining. <br />Baseline observations and photographs have been gathered in the areas with low to moderate <br />rockfall potential that are listed in Section 10.2 prior to mining activities. Evidence of naturally <br />occurring rockfalls, such as remnant boulders of the base of steep slopes, or in the run -out zones <br />of these areas with a rockfall potential have been documented prior to mining. <br />831-032.816 Wright Water Engineers, Inc. <br />October 2018 <br />