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West Elk Mine <br /> <br />2.05-111 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 />Angle of Draw <br />The draw, or limit angle (φ, from a vertical reference) in the Somerset area ranges from about 8 <br />to 21 degrees. See Exhibit 60E. The actual E-seam angle-of-draw has been conservatively <br />estimated at 16.3 degrees (see appendix B of the Spring 2010 Subsidence Report.) The angle of <br />draw is measured using the greatest vertical distance between the top of the E-seam at the nearest <br />edge of each longwall panel and the ground surface elevation equal to the point of no discernable <br />subsidence. As such, the conservative approximate limit of the maximum predicted E-seam <br />angle-of-draw is 19 degrees. <br />Water and Methane <br />Observations of the north and west flanks of Mt. Gunnison during an October 1996 field trip, <br />revealed numerous talus and rock glacier deposits that occur in the valleys and lower part of this <br />intrusive body. Snow melt and rain can easily infiltrate these deposits, which may eventually enter <br />any permeable rocks, faults, fractures, and joints near the mountain. Coal beds and rocks in the <br />deformed zone around Mt. Gunnison might also contain increased methane where the coal is <br />metamorphosed to a higher rank by the intrusive body. Great quantities of water and methane may <br />therefore be expected as coal is mined closer to Mt. Gunnison. <br /> <br />Effects Of Subsidence And Mine-Induced Seismic Activity On Man-Made Structures And <br />Renewable Resources <br />Man-made structures and renewable resources in the South of Divide mining area basically consist <br />of 1) A dam and reservoir (Monument Dam - Minnesota Reservoir), 2) stock watering ponds, 3) <br />streams (primarily Dry Fork and the upper part of Lick Creek), 4) roads, and 5) local cabins. <br />Minnesota Reservoir, the ponds, and the Deep Creek Ditch diversion to Dry Fork serve the dual <br />purpose of being both man-made structures and containment structures for the valuable water <br />resources in the area. Based on past subsidence observations in the Jumbo Mountain, Apache <br />Rocks, and Box Canyon mining areas during the last nine years, the following information is <br />considered appropriate for the South of Divide mining area. <br />Monument Dam - Minnesota Reservoir <br />Monument Dam - Minnesota Reservoir, which provides storage water primarily for irrigation, is <br />located between two landslides—one beginning at the north shore and the other beginning at the <br />south shore. As explained above, landslide movement on Jumbo Mountain occurred during <br />unusually wet periods before mining began, during mining, and after mining and subsidence was <br />complete. The conclusions were that landslide movement occurs in response to ground <br />saturation and is not noticeably affected by subsidence and seismic activity produced by <br />longwall mining beneath, or near, landslide areas. <br />The landslides north and south of Minnesota Reservoir occur in surficial material (loose rock, <br />gravel, sand, silt, clay, and soil) and local bedrock outcrops. The author therefore expects that <br />the mining of longwall panels LWE16 and LWE17 will not noticeably affect the large landslide <br />south of Minnesota Reservoir.