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landslides and the mine is in fact centered beneath a large slope failure <br /> complex. Land use presently consists of habitat for wildlife with no significant <br /> man-made structures above the mine. Shall, one-lane access roads used for <br /> exploration drilling are the only man-made features present. <br /> 3.0 SUBSIDENCE NICt=RIM OVER THE EX[STIM "C" SEA 4 MINING <br /> Semi-annual monitoring of selected monument sites located above the "C" seam <br /> workings has been ongoing since August of 1985. It would appear the monument <br /> sites have been more or less randomly located above various portions of the mine <br /> plan based upon ease of access and visibility from base stations located along <br /> the toe of the slope on the north side of the Gunnison River (see Figure 7 ) . <br /> Therefore, these monuments provide spot information on vertical and horizontal <br /> movements but are not aligned so as to produce a "subsidence profile". <br /> Originally Am Coal Company anticipated high in panel extraction ratios <br /> from pillar robbing upon retreat within the "C" seam. However, as mentioned <br /> previously, due to poor roof conditions above the "C" seam, virtually no pillar <br /> robbing was accomplished. Therefore, the majority of the "C" seam mine remains <br /> at an extraction ratio on the order of 50 percent. Due to the lesser amount of <br /> extraction it would appear that many portions of the mine have not subsided at <br /> all. It appears that other portions have subsided, however, the magnitude of <br /> subsidence is significantly less than was originally anticipated for the proposed <br /> high in panel extraction ratios. A complete summary of the monitoring data will <br /> be found in Appendix A. Graphical stmmories of the vertical displacement of <br /> monuments over time can be seen in Figures 8 - 13. It should be noted that the <br /> data provided in this report is "raw" data with no filtering and no corrections <br /> applied. Review of the data indicates that, in many cases, the data contains <br />