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FALL 2010 SUBSIDENCE AND GEOLOGIC FIELD OBSERVATIONS <br />is Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />1.0 INTRODUCTION <br />Beginning in 2007, Wright Water Engineers, Inc. (WWE) has been conducting semi-annual field <br />visits to the area over the West Elk Mine as operated by Mountain Coal Company, LLC (MCC). <br />Each of these visits provides observations related to subsidence effects resulting from the <br />longwall mining of coal in the B- and/or E-seam and result in a subsidence report . These <br />observations represent at least 80 percent of the text contained within each report. The remaining <br />20 percent is repeated reference text for the convenience of the reader. This is also true of <br />Appendix A which provides a summary of the subsidence prediction information contained in <br />Exhibit 60 - 60E of the current permit issued by the Colorado Division of Reclamation, Mining <br />and Safety (CDRMS). <br />This subsidence report (Fall 2010) is the second of two reports to be generated based on <br />• observations made during the 2010 calendar year. In accordance with MCC's CDRMS permit, <br />subsidence reports are to be submitted by April 30`h (for preceding fall monitoring) and <br />September 30`h (for preceding spring monitoring). Spring-time observations are regularly <br />hampered by limited access due to snow or muddy conditions as occurred this year and fall <br />observations are scheduled around the various hunting seasons. <br />As of this report, WWE and MCC plan to substantially reduce the size of the annual fall <br />subsidence report. Reference will be made to the spring subsidence. report for those details that <br />have been characteristically found in previous reports (e.g., field recognition of subsidence and <br />non-subsidence features, conclusions, and a bibliography). The fall subsidence report will focus <br />on the identification and discussion of only those observations which reflect an obvious change <br />1 Annual subsidence and geologic field observation reports, as well as exhibits to the West Elk Mine permit <br />document (Exhibits 60, 60A5 6013, 60C, 60D, and 60E), are kept at Mountain Coal Company, LLC and at the <br />Colorado Division of Reclamation, Mining, and Safety. <br />• 831-032.792 Wright Water Engineers, Inc. Page 1 <br />April 2011