Laserfiche WebLink
<br /> <br /> <br />Exhibit 60C <br />Subsidence Evaluation and 2004 Geologic Hazard Field Observations <br />West Flatiron Lease Area <br />• Overburden depth at Location 2 to the B Seam is about 2,200 feet. <br />• The estimated natural rockfall potential is locally high for the first 200 to 300 feet of cliffs <br />and over-steepened slopes of the West Flatiron Lease area to moderate below them. <br />• The rockfall potential may increase to a small degree over the natural potential, when the area <br />is mined, however, very little or no effect was observed on the cliffs and steep slopes below <br />them when longwall panels 14 and 15, and the eastern part of longwall pane122 were mined. <br />• Increased rockfalls, however, were observed in the area of very high natural rock potential on <br />the west side of West Flatiron above the approximate midpoint of mined longwall panel 22 <br />(see Figures 22 and 23 of the Subsidence and Geologic Field Observations -Apache Rocks <br />and Box Canyon Mining Areas, July 12-IS, 2004 for more information). The cliffs are higher <br />and the slopes below are steeper than any other area in the Apache Rocks and Box Canyon <br />mining areas. <br />8.3 Location 3 <br />Location 3 is on anortheast-trending ridge between Deep Creek to the southeast and the first <br />southwest-trending draw of the Raven Gulch tributary. The point provides a good view of ffie <br />southwestern part of the West Flatiron Lease area (Figures 5 and 6, and Map 1). <br />831-032.650 <br />November 2004 <br />Wright Water Engineers, Inc. <br />Page 21 <br />