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Spring 2008 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />• This traverse is located mostly above portions of the B-seam coal that have not been, and will not <br />be, mined. The traverse, however, is located in the mining influence of various longwall panels <br />that were mined in the past. Exceptions include a short segment (about 1,500 feet) starting at B <br />which is under unmined Longwall Panel 25 and the last segment (about 3,500 feet) near B', <br />which is over the Box Canyon mains and western ends of mined Longwall Panels 15 and 16. <br />Overburden depth to the B-seam varies from about 450 feet at B and gradually increases to <br />approximately 1,050 feet at B'. <br />Light gray to brown soil, alluvium, and colluvium of the Barren Member of the Mesaverde <br />Formation are exposed along this roadway traverse. The soil, alluvium and colluvium are <br />generally stable due to the relatively gentle grade of the Sylvester Gulch valley bottom. <br />No subsidence features were observed and no photographs were taken. <br />5.3 Traverse C-C' <br />• Traverse C-C' begins at the well site for E-seam methane well no. 1 (ESM-1) over mined B-seam <br />Longwall Panel 13, travels along the main access road to the Box Canyon mining area, and ends <br />at the fork in the drill roads (at D of traverse D-D') above the southern edge of mined Longwall <br />Panel 14. <br />The traverse winds its way above mined Longwall Panels 13, 13A, 17, 16, 15 and 14. Light gray <br />to brown soil, colluvium, and local outcrops of siltstone and sandstone of the Barren Member of <br />the Mesaverde Formation occur in the road cuts. Overburden depth to the B-seam varies from <br />1,000 to 1,650 feet. The colluvium and soil are locally unstable on the road cuts in the steeper <br />areas along the traverse, which causes landslide deposits, primarily on the steep slopes that are <br />common on the middle half of the traverse. <br />The soil/colluvial failure in the road cut, which was observed at Location 1 during the spring <br />2007 observations, was observed again during this field visit and identified as Location 2. <br />r? <br />No subsidence features were observed. <br />831-032.790 Wright Water Engineers, Inc. <br />August 2008 <br />Page 19