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Mountain Coal Company <br />West Elk Mine <br />Semi-annual Subsidence Monitoring Report <br />Mid-year Report 1995 <br />The most current subsidence survey for the West Elk Mine was performed in July and <br />August 1995, by Valley Survey. The survey was conducted using radial and level loop <br />survey methods. The instruments used were a HP 3820 Total Station <br />theodolite/electronic distance measuring equipt (EDM); and a Sokkia B 1 level. <br />The following tables reflect the northings, eastings, average pre-mining elevations, the <br />previous report elevations (October 1994), the current survey elevations, subsidence since <br />the 1994 Annual Monitoring Report and total subsidence. <br />These tables indicate that the maximum total subsidence to date is 8.35 feet and occurs <br />over both the F- and B-Seams at point No. 61, over the center of the 1st Northwest <br />Longwall Panel. The subsidence measured is well within the range of the predicted <br />subsidence for two-seam mining. Complete maximum subsidence can be calculated by <br />simple addition of the maximum predicted subsidence for both the F and B Seams for a <br />total of 10.22 feet. <br />There were no additional visual effects of subsidence reported by the survey contractor <br />during this period of monitoring. <br />Monitoring of a wood-framed structure began after construction was completed in 1994. <br />The structure is located over the pillars between the 5th and 6th Northwest Longwall <br />(NWLW) panels. The monitoring shows an overall lowering of the site an average of 1.52 <br />feet and an average easterly horizontal shift of 1.71 feet after mining the 5th NWLW panel <br />past the structure. An additional 1.15 feet vertical lowering and a shift of the structure <br />back to approximately 0.54 feet northeast of the pre-mining position occurred after mining <br />the 6th NWLW panel past the structure. The total average vertical movement of the <br />structure since the premining survey is minus 2.67 feet. A photo panel control point <br />located nearby over the approximate middle of the 5th NWLW panel lowered <br />approximately 4.17 feet. <br />Mining advance was limited to the B-Seam development in the North Jumbo Mains, the <br />Seventh and Eighth Northwest Headgates and the Eighth Northwest Tailgate, from <br />October 1994 to July of 1995. The longwall retreated in the 5th and 6th NWLW panels <br />since October 1994. The longwall is curtently (September 1995) retreat mining in the 7th <br />NWLW panel. <br />subrep95.doc. <br />