2022-02-22_PERMIT FILE - C1980007 (5)

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West Elk Mine 2.04-21 Rev. 11/04- PR10; 03/18- PR15; 01/22- MR459 indicate that these results are representative of the existing conditions throughout the West Elk coal lease area and that the B, E, and F coal seams and associated roof and floor materials do not contain potential acid- or toxic-forming materials. Core examination and actual observed conditions suggest that the B Seam has the most competent roof rocks of the three mined or minable seams. Immediately overlying the B Seam is from 1 to 2 feet of a dark gray mudstone. This lithology is generally competent, but may locally be weakened where slickensides, fossils, or joints disrupt bedding continuity and rock strength. Above this fine- grained "cap rock", a widespread sandy unit occurs which forms the main roof of the B Seam. This sandstone typically provides good anchorage for roof bolts and forms a strong beam above the mined entries. Locally, this sandy unit may be weakened by jointing or thin, fine-grained laminations, which commonly occur near the unit's base. B Seam roof conditions have historically been excellent. From 1 to 2 feet of top coal is commonly left unmined in the roof to improve roof conditions by eliminating air slaking, which can weaken the immediate roof shale over time. In leaving top coal, sulfur in the coal product is also reduced by avoiding higher concentrations of sulfur that occur near the top of the seam. The base of the B Seam is predominately comprised of siltstone and shale. Because all of the lower coal bench (B3) is left unmined and in place for quality reasons, floor conditions of the normal mining interval are generally excellent. On occasion, floor conditions degrade when mining inadvertently encounters the lower claystone parting (Figure 6). E Seam The E Seam is also an economically recoverable coal reserve in the South of Divide permit area. Like the B Seam, the E Seam and adjacent strata gently dip to the northeast at approximately 3.5 degrees (Map 17). The E Seam outcrops on the northern side of the coal lease area along the North Fork, and on the western side of the leases along Jumbo Mountain and Minnesota Creek, following the pattern of the B and F Seam outcrops (Map 9). Minor b urn areas occur along the outcrop in this area. The E Seam is too low in elevation to outcrop in Sylvester Gulch; however, it does outcrop along the North Fork just to the east at the former Oliver No. 2 Mine portal. E-Seam Lithology The E Seam is a thick and widespread coal deposit of high economic importance within the West Elk Mine coal lease area. The E Seam is comprised of two coal benches, which are separated locally by a rock parting. The upper coal bench is informally denoted as the "E0" Bench and the lower bench as the "E1" Bench (Figure 7). MCC generically uses the E Seam designation for the upper (E0) coal bench or the combined upper and lower benches, where the rock parting is less than 0.5 feet thick. The E Seam thickness is controlled by the splitting of the two coal benches (Map 18). In the central and southern portions of the coal lease area, both E0 and E1 coal benches are merged to form a thick coal body ranging from 15 to 21 feet in total thickness. To the east and west of the