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Fall 2007 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />5.2 Traverse B-B' <br />Traverse B-B' begins at point A' (of A-A') above the southern edge of mined longwall panel 14 <br />and ends at the fork in the drill roads above the southern edge of mined longwall pane124. Soil, <br />colluvium, and local bedrock of the Ohio Creek and Barren Members of the Mesaverde <br />Formation are exposed in the drill road. The soil and colluvium are locally unstable or quasi- <br />stable on the steepest slopes. <br />The overburden depth to the B-seam ranges between 1,625 and 2,175 feet. Observed subsidence <br />related features along this traverse included a crack at location 1 <br />5.2.1 Location 1 (Location 2 of the Spring 2007 Field Visit) <br />Location 1 is a subsidence crack located primarily in soil and colluvium, which trends roughly <br />parallel to the long direction of mined longwall panel 14 near the headgate entries. Figure 5 <br />shows the crack in the bedrock at the road cut. At this location, the exposed crack in the <br />sandstone bedrock decreases in width from approximately 0.25-inch to a hairline over a vertical <br />distance of about 3.5 feet. A photographic comparison to the spring 2007 photograph at this <br />location shows there to be minimal observable differences (see Figure D-1). <br />831-032.780 Wright Water Engineers, Inc. Page 15 <br />November 2007 <br />