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Fall 2008 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />• 16. 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 road traverse. The soil, alluvium and colluvium are generally <br />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' and I of Traverse I-I') above the southern edge <br />of mined Longwall Panel 14. <br />This 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 commonly-occurring <br />steep slopes along the middle portion of the traverse. <br />No subsidence features were observed. <br />5.4 Traverse D-D' <br />Traverse D-D' begins at point C' of Traverse C-C' (and point I of Traverse I-I') above the southern <br />edge of mined Longwall Panel 14 and ends at the fork in the drill roads above the southern edge <br />of mined Longwall Panel 24. Soil, colluvium, and local bedrock of the Ohio Creek and Barren <br />Members of the Mesaverde Formation are exposed in the drill road. The soil and colluvium are <br />locally unstable or quasi-stable on the steepest slopes. <br />• <br />831-032.790 Wright Water Engineers, Inc. Page 21 <br />December 2008