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Fall 2008 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />[??l <br />• <br /> <br />located in graded material capping West Flatiron above the Longwall Panel 19 tailgate. The <br />overburden depth to the 13-seam in this area is about 2,200 feet. The drill site is constructed <br />primarily in soil and colluvium derived from the Wasatch Formation. <br />No subsidence related features were observed at this location. <br />5.6 Traverse F-F' <br />Traverse F-F' is a short traverse that starts at the fork in the main West Flatiron drill road (E-E' <br />traverse) and heads westward to the drill pad containing MDWs 19-04 and 19-05 (Location 8). <br />This traverse is above the eastern part of mined Longwall Panel 19 primarily in clays and silts of <br />the Wasatch Formation. Overburden depth to the B-seam is 2,200 to 2,250 feet. <br />Location 8, which also is Photographic Observation Point 2, provides a good southward view of <br />the rockfall/landslide area above mined Longwall Panel 22. This is an annual observation <br />location for this area because this vantage point provides a clear view of the steep cliffs along the <br />west side of West Flatiron. This point was also used earlier this year to photograph a new <br />rockfall/landslide at Location 9 (approximately 1,500 feet north of Location 4). <br />5.6.1 Location 8 (Location 8 of the Spring 2008 Field Visit) <br />The previously noted failure of the southwest corner of drill pad MDWs 19-04 and 19-05 at F' of <br />Traverse F-F' in the spring 2008 field visit is no longer observable due to the reclamation of the <br />drill pad and surrounding area (Figure 17). No evidence of the former pad and its partial failure <br />is now present. Previously observations made at this pad lead to a conclusion that the pad failure <br />was primarily the result of differential settlement of the large amount of fill needed to level the <br />southwest corner of the pad. <br />The central portion of Figure 17 and 18 (taken during spring 2008) represent relatively similar <br />perspectives. This comparison reveals the significant changes that have occurred at this location <br />due to reclamation of the site. <br />831-032.790 <br />December 2008 <br />Wright Water Engineers, Inc. <br />Page 32