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2005 Subsidence and Geologic Field Observations Box Canyon, West Flatiron, Apache Rocks, and South of Divide Mining Areas 4.9 Traverse H-H' Traverse H-H' begins at a fork off main drill road of traverse G-G' and ends at MDW 24-04. This traverse is above the eastern, mined part of longwall panel 24 in deep brown to gray soil and colluvium. Overburden depth to the B-Seam ranges from 2,200 to 2,250 feet. No subsidence features were observed; however, irregular desiccation cracks %8 to t/z inch wide were located on the drill pad. 4.10 Traverse I-1' Traverse I-I' begins at the fork in drill roads above the southern edge of the mined part of longwall panel 24, the barrier pillar between the Box Canyon and Apache Rocks mining areas, mined longwall panel 14, the northern edge of mined longwall panel 15, and ends at the fork in drill roads above mined longwall panel 14. Soil, colluvium, and local bedrock outcrops of the Ohio Creek and Barren Members of the Mesaverde Formation were observed along this traverse. Overburden depth to the B-Seam varies ' from 1,625 to 2,175 feet. No subsidence features were observed, except the crack observed at Location 10. 4.10.1 Location 10 Location 10 is a subsidence crack located 300 feet north of the headgate road pillars of mined longwall panel 14. The crack, which trends roughly pazallel to the longitudinal direction of the longwall panel 14, is 4 to 6 inches wide in the colluvium, narrows to about 1 inch at the top of the sandstone, and becomes a closed fracture a few feet down in the sandstone (Figure 11). Subsidence processes would normally be expected to be complete within about a year after mining in the underlying longwall panel is completed. However, mine-related cracking may continue for a longer period on steep slopes, such as is the case at this location. 831-032.710 Wright Water Engineers, Inc. Page 23 November 2005