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Subsidence Field Observations <br />West Elk Mine <br />August 27-29, 2002 <br />4.0 OBSERVATIONS AND EVALUATIONS ALONG TRAVERSES AND AT <br />INDIVIDUAL LOCATIONS ON AUGUST 27 THROUGH 29 <br />4.1 Subsidence Observations and Evaluations on August 27, 2002 <br />Traverses A-A' through F-F' were made along drill roads and trails in the Upper Sylvester <br />Gulch-West Flatiron area (Map 1, also see video for further details). <br />4.1.1 Traverse A-A' <br />The traverse extends along the road from Two Ponds along a new road to Drill Site 15-05. <br />• traversed the approximate midpoints (lengthwise orientation) of mined-out longwall Panels <br />14 and 15. Road cut exposures were predominantly colluvium and soil, but also exposed 10- <br />15%bedmck composed of claystone, siltstone, and sandstone. <br />• Overburden depth to B-Seam ranged from 1,100 to 1,550 ft. <br />• Some irregular cracks and fractures were observed. Desiccation cracks were also locally <br />observed in the colluvium. <br />• Most of the cracks observed in the colluvium and bedrock were most likely caused by <br />construction activities (perhaps as much as 75%), some were likely caused by subsidence <br />(25%). <br />4.1.2 Traverse B-B' <br />This pre-mining traverse starts at the fork in the new drill road towards Deep Creek and thence <br />along a new road to Drill Hole SOM-54. <br />• Mostly colluvium and soil are exposed in the road cut, along with local outcrops of <br />sandstones and siltstones of the Ohio Creek Member of the Mesaverde Formation. <br />831-032.570 Wright Water Engineers, Inc. Page 7 <br />December 2002 <br />