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

Home Browse Search

West Elk Mine • F Seam Stratigraphically, the F Seam is the uppermost mineably thick seam in the permit area. Coal was mined from the F Seam from 1982 to 1991 by the West Elk mining operation. Ultimately, reduced seam thickness, poor roof conditions, and rock partings degraded product quality sufficiently to make continued mining of the F Seam uneconomic. Portions of the West Elk F Seam mine aze used to access the active B Seam mining operations, however, there are no plans to produce coal from the F Seam in the future. The F Seam and adjacent strata gently dip to the northeast at approximately 3.5 degrees (Map 21). The strike also changes to east-west and the dip flattens to approximately one degree to the north in the Box Canyon permit revision area. The F Seam outcrops on the northern side of the coal lease area along the North Fork, on the western side of the lease block on Jumbo Mountain, and along the South and Dry Forks of Minnesota Creek. The best exposures aze along the west and south-facing escarpments from just north of the Dry Fork of Minnesota Creek and to the south of Lick Creek. Limited exposures of the F Seam azea occur along the northern portions of Sylvester Gulch. The remainder of the outcrop is covered by vegetation and soils. Burn areas occur predominantly on south and west-facing slopes. Burn is not extensive or continuous along the outcrop. F Seam Lithology . The F Seam is a relatively thick and widespread coal deposit within the West Ells Mine coal lease azea. This seam typically occurs as a single coal bench, although locally, partings do occur within the seam. Within the coal lease azea, the F Seam typically ranges from 5 to 9 feet in thickness and averages azound 7 feet (Map 22). Most of the thickness variability occurs in the southern portion of the leased azea. Within the perrnit area, the F Seam is persistent in thickness, however, abrupt local reductions in seam thickness occur where overlying channel deposits have scoured into the underlying coal. Although the F Seam is generally represented as a single, clean coal bench, bony or shaley partings or other impurities often occur within it. When shale partings do exist, they aze commonly located in the lower half of the coal seam. Such shale partings were encountered within the West Elk Mine, which degraded product quality. Bone horizons also occur, particulazly at the top and the bottom of the coal seam. FSeam Reserves Although the F Seam coal deposit is marginally thick (avg. 7.0 feet) within the coal lease azea, previous attempts to produce coal from the F Seam have proven to be uneconomic. Localized scouring by overlying channel deposits and azeas where partings thicken near the base of the seam, served to further reduce the full seam thickness. The limited seam height was worsened by poor roof conditions and as a result, product quality was degraded, eliminating any competitive advantages and making mining of the F Seam unprofitable. Based upon past • mining experience and because economic recoverability is a reserve criteria, reserves have not been estimated for the F Seam, nor aze there plans to produce coal from this seam in the future. 1.04-32 Revised November 2004 PRIO