2006-06-02_PERMIT FILE - C1980007A (3)

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West Elk Mine • Several factors limit the mineable B Seam reserve (Map 13). On the north end of the coal lease azea the recoverable B Seam reserve is limited by Bear Coal Company's abandoned C Seam mine workings. Because these mine workings closely overlie the B Seam (30 to 60 feet), the B Seam is considered un-mineable using longwall mining methods. This operating and safety limitation is designed to assure that no connection between the adjacent mines would occur as a result of undermining. Other portions of the reserve are bounded by geologic factors. In the northern portions of the Jumbo Mountain lease tract area, the B Seam reserve is limited by an ancient landslide deposit. In that azea, a massive slide has removed the upper mineable portion of the B Seam. To the west, south, and east, the B Seam mineable reserve may be limited by increasing parting thickness as the B Seam coal benches diverge. Access slopes from the F Seam workings enter the B Seam in the southwest quarter of Section 21, T13S,1290W, 6th P.M. This location provides ready access to the B Seam coal in the pemut azea. B Seam Overburden and Interburden B Seam overburden ranges from zero at the outcrop along the North Fork and Minnesota Creek drainages to 2,300 feet beneath West Flatiron Mesa, on the east side of the coal lease area. Within the existing West Elk Mine permit azea, the average overburden thickness is about 1,000 feet (Map 14). Within the South of Divide permit revision area, the overburden ranges from • 200 feet to 2,300 feet and averages approximately 1,200 feet. Interburden between the B Seam and the overlying E Seam ranges from 200 to 300 feet over the permit area (Map 15) and between 225 and 300 feet in the South of Divide permit revision azea. The interburden between the B Seam and the overlying F Seam ranges from 320 feet to 450 feet (Map 16) over the current permit area and between 320 and 400 feet in the South of Divide permit revision area. The B/F Seam interburden includes the C, D, and E Seams, of which only the E Seam is of significant economic importance over the permit area. Lithologies within the B/E Seam interburden consist of shales, siltstones, and coals. Sandstones are generally lenticular, with the exception of the massive Bowie Sandstone. This sandstone unit usually lies close under the bottom of the D Seam, and ranges from 20 to 225 feet thick. It can be divided into two laterally continuous sandstone bodies which have informally been designated as the "Upper Marine Sandstone" and the "Lower Marine Sandstone" (Figure SA, Figure SB, Figure 5C, Figure SD, Figure SE, and Figure SF). In the western portions of the initial mining area and into the Jumbo Mountain lease tract, only the lower lobe of this sandstone body occurs (Figure SB, Figure SD, and Figure SF). I-~ U 2,04-26 Revised November 2004 PRI G