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Fall 2008 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />0 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 entries. This traverse winds northward <br />along a drill road above mined Longwall Panels 24 to 19. Overburden depth to the B-seam <br />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 along this traverse in 2006 and 2007 <br />including several above the northeastern edge of mined Longwall Panel 19 (on the northern edge <br />of the drill pad for MDWs 19-01, 19-02, and 19-03; Location 6) and adjacent to the drill road <br />above the northeast comer of mined Longwall Panel 21 (in the drill pad for MDWs 21-32, 21-36, <br />and 21-38), respectively. This latter location (Location 4) has been recently reclaimed and <br />surface evidence of the previously observed cracks has been mostly lost due to regrading. The <br />former location (Location 6) shows no remaining signs of the former cracks. <br />Location 7 represents the new terminal point of this traverse (approximately 500 feet north of <br />Location 6). <br />5.5.1 Location 4 (Location 5 of the Spring 2008 Field Visit) <br />This is the site of extensive cracks first observed during the spring 2007 field visit. These cracks, <br />observed both in the main West Flatiron drill road and in the drill pad for MDWs 21-32, 21-36, <br />and 21-38, occur above mined Longwall Panel 21 (Map 1). The maximum cumulative extension <br />of the crack sequence was estimated to be 2`/2 to 3 feet at the time of our site visit in June 2008. <br />However, observations made during our fall 2008 field visit show there to be virtually no <br />evidence of these cracks in that the drill pad has been regarded and reclaimed (Figures 11 and <br />12). <br />• <br />831-032.790 Wright Water Engineers, Inc. Page 25 <br />December 2008