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Fall 2008 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />• subsidence monitoring report with specific survey data summarized in Appendix B and shown on <br />Map B-1. <br />Also during fall 2008, MCC completed a second baseline survey (the original was completed in <br />fall 2007) to establish the pre-mining topographic profile of the Dry Fork Minnesota Creek (Dry <br />Fork) thalweg. The original information was reported in Section 3.2 of the fall 2007 subsidence <br />monitoring report with detailed mapping provided in that report as Appendix C. The fall 2008 <br />survey is discussed in Section 3.2 of this report and the survey data is provided in Appendix C. <br />Lastly, MCC has been collecting data from numerous monitoring locations in and around <br />Minnesota Reservoir and Monument Dam. A general discussion of the data collected to date is <br />provided in Section 3.3 with the specific data provided in Appendix D. <br />3.1 E1 Panel Subsidence Monitoring Grid <br />The West Elk Mine has historically extracted coal mainly from the B-seam of the Mesaverde <br />Formation. Future mining will also include the E-seam (approximately 300 feet above the B- <br />seam), primarily in the SOD mining area. As part of the ongoing data collection and monitoring <br />programs required under its permit, a new E-seam subsidence monitoring grid was proposed, <br />developed and recently constructed. This grid is located above E-seam Longwall Panel 1 (E 1) <br />and is comprised of 120 points in one longitudinal and two transverse monument lines relative to <br />the panel orientation (see Map 1 and Map B-1 in Appendix B). This is the first panel to be <br />mined in the E-seam. The two transverse traverses extend beyond the gate road of Longwall <br />Panel E1 both to the north and south. The southern end of these traverses extends to <br />approximately the middle of Longwall Panel E2 (at least 700 feet outside the edge of the panel). <br />Appendix B provides the point number, northing coordinate, easting coordinate, and elevation at <br />each of the 120 observation points in comparison to the same survey conducted in the fall of <br />2007. This comparison includes a column which represents the relative elevation difference <br />between the two surveys. Please note that 2008 construction activities along the access roads <br />over the El panel resulted in the destruction of twelve survey monuments. All but two of these <br />monuments have been subsequently reset and resurveyed as represented in Appendix B. As <br />831-032.790 Wright Water Engineers, Inc. Page 10 <br />December 2008