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Spring 2008 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />• New vegetation can be observed in portions of the fall area, particularly in the lower part, which <br />indicates some stability. However, fractures in the massive sandstone cliff indicate that more <br />rockfalls may eventually occur under the influence of gravity, freezing, and thawing. <br />5.5 Traverse E-E' <br />Traverse E-E' begins at the fork in drill roads above the south gate road entries of Longwall <br />Panel 24 and ends at the drill pad containing MDWs 18-39, 18-40, 18-41, and 18-43 near the <br />northeast corner of the mined Longwall Panel 19 tailgate. <br />The traverse winds northward along a drill road above mined Longwall Panels 24 to 19. <br />Overburden depth to the B-seam varies from 2,150 to 2,250 feet along this traverse. <br />Soil and colluvium as much as 10 feet thick, derived from clays and silts of the Wasatch <br />Formation and the underlying Ohio Creek Member of the Mesaverde Formation, were <br />encountered on the road. Several cracks were observed in 2006 and again visited in the spring of <br />2008 above the northeastern edge of mined Longwall Panel 19, on the northern edge of the drill <br />pad for MDWs 19-01, 19-02, and 19-03 (Location 6). New, actively widening and lengthening <br />cracks were observed both in the drill road and in the MDWs 21-32, 21-36, and 21-38 drill pad <br />area (on the west side of the road) over the northeast corner of mined Longwall Panel 21 were <br />also visited again in the spring of 2008 (Location 5). Location 7 represents the new terminal <br />point of this traverse (approximately 500 feet north of Location 6). <br />5.5.1 Location 5 (Location 3 of the Fall 2007 Field Visit) <br />is <br />This is the site of extensive new cracks, which were first observed during the spring 2007 field <br />visit. These cracks, which are located both in the main West Flatiron drill road and in the drill <br />pad for MDWs 21-32, 21-36, and 21-38, occur above mined Longwall Panel 21 (Map 1). The <br />maximum cumulative extension of the crack sequence was estimated to be 21/2 to 3 feet at the <br />time of the most recent site visit (June 4th). These cracks are located at one of the two narrowest <br />portions of the West Flatiron ridge where the overburden depth to the B-seam is about 2,150 feet. <br />831-032.790 <br />August 2008 <br />Wright Water Engineers, Inc. <br />Page 24