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2005 Subsidence and Geologic Field Observations <br />Box Canyon, West Flatiron, Apache Rocks, <br />and South of Divide Mining Areas <br />3.0 OVERVIEW OF FIELD STUDIES DURING JULY 2005 <br />A 4-wheel drive vehicle was used [o facilitate field observations. The vehicle was efficient and <br />effective, except for ATV trails, where it was necessazy to make foot traverses. <br />Prior field observations and experience in the West Elk Mining area during field studies over the <br />past 10 yeazst has indicated that mine subsidence features (cracks and bulges) will most likely <br />occur, or be visible, on roads and trails, where the ground is more compact. These areas, in <br />addition to certain areas free of brush, were therefore selected in order to obtain maximum <br />subsidence information most efficiently. <br />Field observations, which also include the chazacteristics of certain U.S. Forest Service water <br />resources stock ponds, in the West Elk Mine area were conducted in the I) Box Canyon, 2) West <br />Flatiron, 3) Apache Rocks, and 4) South of Divide mining areas. Mining in the first three azeas <br />is (or will be) done in the B-Seam (Map 1). In the South of Divide mining area and the western <br />part of the Apache Rocks mining area, mining is planned for the E-Seam (Map 2). Geologic <br />hazazds (rockfalls and landslides) for the Box Canyon, West Flatiron, and Apache Rocks mining <br />' areas are shown on Map 3 and for the South of Divide mining area on Map 4. <br />' Fieldwork began in the West Flatiron and Box Canyon mining areas and progressed southward [o <br />the South of Divide mining area. The field observations and evaluations part of this report is <br />' arranged in the same order as the field work: Section 4.0-B-Seam mining in the Box Canyon, <br />West Flatiron, and Apache Rocks mining azeas and, Section 5.0-E-Seam mining in the South of <br />' Divide mining area and in the western part of the Apache Rocks mining area. The parts of this <br />report that are discussed together are [he: 1) Section 1.0 Summary of Major Findings, 2) Sections <br />' 6.0 and 7.0 Analysis and Evaluation of the Effects of Longwall Mining on Rockfalls and <br />Landslides, and 3) Section 9 Conclusions. Video and high-resolution still images were taken as <br />' necessary to further describe a particulaz geologic ormine-related feature. <br />' Annual subsidence and geologic hazazd reports are kept at Mountain Coal Company, LLC and at the Colorado <br />Division of Minerals and Geology, as well as exhibits [o [he permit document (Exhibits 60, 60A, and 60B). <br />831.032.710 Wright Water Engineers, Inc. Page 7 <br />November 2005 <br />