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PIT LOCATION OVERBURDEN AVG. TK. FT. COAL AVG. TK. FT. WEB PILLAR THlCKNESS* Seneca II-W (Wadge Seam) - Block A 200' 12.8' 11 FT. Seneca !I-W (Lennex Seam) - Block A 220' 6' 8 FT. Seneca U-W (Wedge Seam)- Block B 213' 12.0' 11 FT Seneca II-W (Lennex Searn)- Block B 220' 6' 8 FT. Ser:eca II-W (Wadge Seam) - Block C 264' 10.5' 12 FT. Seneca II-W (Sege Creek Seam) - Block D 180' S.0' 6 FT. Seneca II-W (Lennex Seam)- Block B 220' 6' 8 FT. Seneca II-W (Wolf Creek Seam) - Block D 276' I Z.7' 19 FT. Yoast-(Wadge Seam) - BlockA 240' /0.5' 11 FT. Yoast -(Wadge Seam)- Block B 164' 11.1 ' 8 FT. Yoast -(WoljCreek Seanr) - Block C 240' /6.0' 13 FT. Yoast-(Wolf Creek Seam) - Block D 212' 12.0' 11 FT. Yoast -(Wadge Seam)- Block E 234' 13.2' 12 FT. The web pillar widths were determined by using ARMPS software with a 625 psi mass seam strength and a minimum 1.3 factor of safety The mass seam strength is an average based on testing and modelling by Highwall Mining Services. The 1.3 minimum factor of safety was derived from experience in using ARMPS for HWM web pillar design in the western US and Australia. Average overburden and seam thickness for the entire reserve block were used in the calculations. Entry Width is assumed to be 11 ft. 9. Highwall mine blocks at Seneca II-W Yoast Mines will be mazked both in the pit and on the highwall above showing the delineation line between each azea. A typical pit cross-section for each area has also been included in Attachment A. 10. Barrier pillars have also been added to the plan at Seneca II-W. They will be a minimum of Z50 feet in width and will be placed in the approximate areas as show on Exhibit 12-3b. 1 I. Should the active hole being highwall mined intersect the previous hole, the highwall miner will pull oul immediately at that point, skip the next adjacent hole and then go on to highwall mined again. COMPANY OFFICIAL SIGNA TITLE: ~~_E'G-``~~ DATE: C , ~ `~ ~ C~.