2010-05-03_REPORT - C1980007 (9)

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Fall 2009 Subsidence and Geologic Field Observations Box Canyon, Apache Rocks, and South of Divide Mining Areas • and across the east end of E-seam Longwall Panels E1, E2 and E3 to a connection with the Dry Fork road near the eastern edge of Section 34, T13S, R90W of the 6`" P.M. (see Maps 1 and 2). Weathered and fractured siltstone, claystone and sandstone bedrock is exposed in several roadcuts along the steeper portions of this traverse. Flatter portions of the traverse are generally stable and on mostly soil and colluvium derived from the Wasatch Formation and from intrusive rocks of the West Elk Mountains which surficially blanket much of the SOD mining area. Overburden depths along this traverse vary from 1,390 to 1,600 feet over the B-seam and 1,100 to 1,300 feet over the E-seam. New drill pads were constructed for MDW E1-52/53 and MDW E1-48 between June and October 2008. These pads are located near the eastern end of Longwall Panel E1 as shown on Maps 1 and 2. These pads were designated as Locations 8 and 9 along Traverse I-I' and above a portion of Longwall Panel E1 that had already been mined (see Map 2). 5.11.1 Location 8 Location 8 is on the drill pad for MDW E1-52 and E1-53. This location is near the eastern end of Longwall Panel El. As with many of the MDW pads located over Longwall Panel El, this site has extensive fill on one side of the pad (i.e., opposite the cut slope). Based on observations of the materials exposed in the cut slope of the pad, this area is comprised of unconsolidated deposits derived from rocks of the Wasatch Formation and from intrusive rocks of the West Elk Mountains overlying consolidated bedrock units (mostly sandstone and shale) of the Barren Member of the Mesaverde Formation. Observations made at this location during our spring 2009 field visit found there to be numerous cracks (Figure 36) near, and oriented sub-parallel with, the outer edge of the pad. As stated in the spring 2009 Subsidence Report, these cracks are believed to be the result of differential settlement of drill pad fill material although mining beneath this area may have exacerbated the cracking to some degree. This conclusion was reached primarily from the observation of similar cracks, with similar orientations, at numerous other pads located over Longwall Panel E1 • (including several above unmined portions of the panel). Further evidence that these cracks are 831-032.791 Wright Water Engineers, Inc. Page 45 April 2010