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

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West Elk Mine • B Seam Roof and Floor Representative samples of the B Seam coal, overburden, roof, and floor strata have been collected and analyzed from core holes drilled within the mine permit area, and elsewhere azound the lease holdings. The locations of these holes aze shown on Map 8 and the analytical results are presented in Exhibit 13. Stratigraphic cross-sections and geochemical analyses indicate that these results aze representative of the existing conditions throughout the West Elk coal lease azea 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 dazk 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 condi$ons 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 neaz 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 umnined 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 the primary economically recoverable coal reserve in the proposed South of Divide permit revision 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 burn azeas 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 Oliver No. 2 Mine portal. 2.()4-27 Revised November 1004 PR70