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Mountain Coal Company West Elk Mine Semi-annual Subsidence Report Mid-Year Report The most current subsidence survey for the West Elk Mine was performed in June, July and August 1994, by Messenger and Associates. The survey was conducted using radial and level loop survey methods. The instruments used were a Wild, T-l, theodolite; a Nikon-ND 20, distance meter; and an unspecified level. The following tables reflect the northings, eastings, average pre-mining elevations, the previous report elevations (October 1993), the current survey elevations, subsidence since the October 1993 report and total subsidence. The following tables indicate that the maximum total subsidence to date is 8.44 feet and occurs over both the F and B Seams at point No. 41, which is over the center of the 1st Northwest Longwall Panel. The subsidence measured is well within the range of the predicted subsidence, (Exhibit 60). In this area of two-seam mining, complete maximum subsidence can be calculated by simple addition of the maximum predicted subsidence for both the F and B Seams. The total predicted subsidence for the 2-seam mining is 10.22 feet. The visual effects of subsidence for this survey period were limited to a lazge surficial crack located near the mid-point of the south-line of Section 17, Township 13 South, ~ ~/ • Range 90 West, 6th P.M. near the Bear Mine workings and the West Elk Mine F- seam ~,~. 2 West, 1 North room and pillar panel. The crack was surveyed and recorded as a 5' wide ,,~ ~.;1~,~ ~-~. ~'~-~ ~ crack, 50' long, and about 30' deep. This crack runs east to west. Other aged, but healing, / J cracks appear over the second, third, and fourth B-Seam longwall panels. These cracks are rr l~ ~ ,,,4• northwesdsoutheast trending and were located directly over, or centered over, the panels. • I~~ 1 L Y 1 ~,U The cracks were various widths, from approximately two inches to 16 inches. The lengths I, ~ ~'~ ~ • ~ of the cracks were discontinuous, but did not exceed 100 yards in any length of run. Displacement at or near the cracks was not perceptible. The cracks seen last year over the . ! ~ • ' •~j B-Seam, 1st Northwest Longwall Panel, are healing well and many are not perceptible. This is due in part to strain relief over the other longwall panels. ~.• ` j~v -,~~,;[ ~~ 3 ° /~ •• ~ ~ > Mining advance was limited to the B Seam development in the B-West Mains, and the ~, '~ ' Fourth, Fifth, and Sixth Northwest Headgates, from October 1993 to July 1994. The ~" ~~ Ion all retreated in the B3, and B4 Northwest Lon all Panels W since October ~~ o ~' ~' (Ny'i'L ) `~ `1' ;~ 1993. The longwall is currently (August 1994) being set-up in the BS NWLW Panel. . ~ ~~~ ti ~ ~ 1 i / 1 1