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Spring 2009 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />• <br />4.0 OVERVIEW OF SPRING 2009 FIELD STUDIES <br />This subsidence report is the first of two reports to be generated during the 2009 calendar year. <br />Biannual reports were initiated in spring 2007. According to the permit, such reporting is to be <br />submitted to Colorado Division of Reclamation, Mining and Safety (CDRMS) by April 30 <br />(spring) and October 31" (fall). However, springtime observations are regularly hampered by <br />limited access due to snow or muddy conditions as occurred this year. For example, persistent <br />snowstorms prevented field observations this April while prolonged cooler weather caused <br />additional precipitation and muddy conditions throughout much of May. As a result, the spring <br />2009 field work could only be adequately conducted in the latter part of May. <br />Subsidence observations were conducted in the Box Canyon, Apache Rocks, SOD, and Dry Fork <br />mining areas. Field observations were made from a 4 -wheel drive vehicle and by foot travel to <br />efficiently complete the required work. <br />• Prior field observations and experience in the West Elk Mine area during field studies over the <br />last fourteen years' (1996 to 2009 inclusive) indicate that subsidence features (cracks and bulges) <br />are most visible on roads and trails, where the ground is more compact and free of brush. These <br />areas were therefore selected, in addition to undermined areas free of brush, in order to most <br />efficiently obtain maximum subsidence information. <br />The rockfalls and landslides in the Box Canyon, Apache Rocks, and SOD mining areas were <br />examined and photographed to evaluate changes since the last observation (using routinely <br />visited photographic observation points), and to record their condition for future reference (Maps <br />1 -4). <br />Eleven photographic observation points have been established since 2007 (see Map 1). Many of <br />these locations had been used for annual comparative purposes even before their most recent <br />' Annual subsidence and geologic hazard reports are kept at Mountain Coal Company, LLC and at the Colorado <br />Division of Reclamation, Mining, and Safety, as well as exhibits to the permit document (Exhibits 60, 60A, 6013, <br />• 60C, 60D, and 60E). <br />831 - 032.791 Wright Water Engineers, Inc. Page 14 <br />November 2009 <br />