2011-09-23_REPORT - C1980007 (7)

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• • • 5.2 Traverse I -I' Spring 2011 Subsidence and Geologic Field Observations Box Canyon, Apache Rocks, and South of Divide Mining Areas Traverse I -I' begins at point D (of Traverse D -D') above the southern edge of mined B -seam Longwall Panel 14 and continues southward across the central portion of mined B -seam Longwall Panels 14 to 17 and across the east end of mined E -seam Longwall Panels El and E2 and unmined E -seam Longwall Panel E3 to a connection with Dry Fork Road near the eastern edge of Section 34, T13S, R9OW 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 that 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 -48 and MDW E1- 52/53/55 between June and October 2010. These pads are located near the eastern end of mined E -seam Longwall Panel El (Maps 1 and 2). The deepest fill on the MDW E1- 52/53/55 pad slopes down to the main Traverse I -I' drill road. This steep slope is subject to failure due to saturated conditions similar to those that occurred over the winter and spring. Figure 6 shows this failed area from along the Traverse I -I' main drill road. Ongoing downslope movement of the deepest fill on MDW E1 -48 pad has now resulted in a sizeable failure. This area is discussed as Location 1 of this report. 831 - 032.793 September 2011 Wright Water Engineers, Inc. Page 16