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Fall 2010 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />• 3.3.1 Location 2 <br />The drill pad for MDW E1-19 is the site of Location 2. This location is below the topographic <br />ridgeline that separates the Dry Fork drainage from the Sylvester Gulch drainage (Map 2). This <br />site is near the tailgate entries above mined E-seam Longwall Panel E1. E-seam overburden <br />thickness at this location is approximately 850 feet. <br />Sometime prior to the spring 2009 field visit, a slope failure occurred on the cutbank above the <br />drill pad at the point where the steep access road expands onto the pad. The failed material <br />included boulders as large as 3 feet in diameter which traveled downslope and up against the <br />chain-link fence surrounding the pump trailer. The slide material was removed and the pad <br />regraded at the time of our fall 2009 field visit. Noted cracks in the pad at that time were minor <br />and associated with differential settlement of fill material. <br />During the spring 2010 field visit (i.e., after longwall mining had passed beneath the area), it was <br />noted that the cutbank side (western edge) of the pad had been benched above a sandstone <br />• outcrop to reduce further sloughing onto the pad. Numerous sub-parallel cracks were observed <br />on the southeast edge of the pad in the location of greatest fill. This portion of the pad was also <br />noted to have an outward slope. It was considered likely that subsidence had played a part in the <br />continued settlement of the southeast corner of the pad (Figure 3). In fall 2010, the southeast <br />corner of the pad exhibited cracks with wider and deeper dimensions (Figure 4). Rounded edges <br />and small collapse features demonstrate weathering which, in turn, indicates little recent <br />movement. <br />831-032.792 Wright Water Engineers, Inc. Page 9 <br />April 2011