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Wesr Elk Mine B-Seam Lithology • The B-Seam is the thickest and most widespread coal deposit within the pernut azea. The B-Seam typically comprises three coal benches sepazated by persistent rock partings. The coal benches have been designated in descending sequence as B ] , B2, and B3 (Figure 6). The minable portion of the B-Seam occurs at the top of the seam where the B I and B2 benches aze c]osely associated and attain sufficient combined thickness. In these azeas, the upper coal benches aze thinly sepazated by a parting informally called the "Marker Parting." These upper two coal benches and the thin intervening parting comprise the low ash or "clean" portion of the B-Seam. Beneath the B2 coal bench, a thick rock parting sepazates the minable portion of the B-Seam from the lowermost, impure B3 coal bench (Figure 6). Because of its position neaz the base of the mining interval, this parting is informally called the "Lower Parting." The underlying B3 coal bench contains numerous bone and shale partings, and as a result, is not of salable quality. This coal bench grades downwazd and laterally into a cazbonaceous shale. The contrast in coal quality between the upper, minable portion of the B-Seam and the impure, lower bench is shown in Table 2, along with the average as-shipped quality of the B-Seam. Table 2 Average Coal Quality • ~I Upper Lower Parameter B-Seam B-Seam B-Seam E-Seam F-Seam Moisture (%) 7.7 7.8 9.4 10.7 10.0 Ash (%) 7.1 16.8 9.2 9.4 9.7 BTU (%) 11,900 10,800 11,700 11,550 11,300 Sulfur (%) 0.6 0.4 0.5 0.4 0.5 Note: As-Received Basis As-Shipped Basis Because the coal benches split near the margins of the coal deposit, the B-Seam ranges in total thickness (B1, B2, and B3) from 1.5 feet to 26.5 feet across the coal lease area (Map 13). Those areas where B-Seam splitting, parting thickening, or coal bench thinning limit the economic recovery of the reserve are identified (Map 13). Within the main body of the coal deposit and in the permit area, the thickness of the B-Seam reserve is much less variable because the upper and lower coal benches (B1 and B2) remain close together. In this area the B-Seam ranges from 14.0 feet to 26.5 feet in total thickness. Map 12 shows the combined total thickness of the B1 and B2 coal benches and that portion of the B-Seam which is economically recoverable. 2. ~-26 Revisedlun. f 995 PR06, Revised Jan. 1998 PR08