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The Division should also recall that in their correspondence dated July 6, 1995 CTL/Thompson <br />reviewed the West Pit Fill and the West Pit Sedimentation Pond slide azea. In this eazlier correspondence <br />they concluded that sealing of coal seams below the Y Seam complex would not be required because these <br />seams pass below the Fill and the west Pit Pond azeas. CTU'Iltompson also noted that sealing of the Y <br />Seams would not be necessary because they would be located well above any theoretical future water table <br />in the West Pit backfilL. <br />In theQ attached wrrespondence (dated March 18, 1996), CTIJThompson believes that, based again <br />upon the more deta~7ed mine plan information curr®tly available, their previous July 6, 1995 recommendation <br />to rescind the requirement to provide a clay seal at each coal seam location remains valid. The important <br />points of the two letters can be ~,*~,,,,a,;~Pd as follows: <br />A) The more refined geological information obtained from the recent West Pit exploration <br />activity indicates that the X seam lies 70 to 80 feet below the Y Seam complex outcropping near the <br />toe of the Fill and the land slide area in the vicinity of the West Pit Pond. The information also <br />indicates also that X seam never outcrops in any area of concern, rather it passes well under the Fill. <br />B) The elevation ofthe low point of X seam coal removal on the north low wall is at 7010 feet. <br />The lowest point of the future multiple seam pit low wall crest is located at the point where the pit <br />crosses the East Taylor drainage at the 6990 elevation. If in the future, if an unexpected water table <br />were to develop in the West Pit it would be expressed at this location, twenty feet below X seam. <br />As such, a theoretical future water level could never rise to the X Seam elevation. <br />C) CTI/Thompson notes that the Sll underdrain is above X-seam <br />The elevation ofthe West Prt FHI underdrain, at the point where it intersects the north mining <br />limit, is located at approximately 7060 feet. The underdrain will be located high and dry by <br />approximately 70 feet above any future water table in the west pit and 50 feet above the X Seam The <br />Y seam complex, which some speculate may have contributed to the landslide azea problem, will also <br />be located high and dry, approximately 140 feet above any future water table. <br />D) Based upon the updated information available for the West Pit, since X Seam and the lower <br />coal seams considered for future augering aze located stratigraphicallybalow the West Pit F~71 and <br />the West Pit Pond slide azea, CTLlfhompson believes that sealing of coal seams under any situation <br />is no longer required. <br />E) CTI,/Thompson notes that, as a precaution, Colowyo will place a shallow lift of spoil up <br />against the highwall sufficient to cover the boreholes. The material will come from the adjacent <br />shovel operation and the compaction afforded by the 240 ton trucks will be sufficient to seal the <br />holes. <br />In conclusion, Colowyo believes the Division's concerns have been addressed. <br />1. Perimeter markers (steel fence posts) aze appropriate for monitoring the Auger Area #2 and have <br />previously been acknowledged by the Division as a more accurate method than surface monitors. <br />2. Based upon more detailed information available regazdmg the West Pit minepbm, CTL/Thompson <br />