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West Elk Mine <br />2.04-48 Rev. 11/04- PR10, 04/06- PR10, 09/07- PR12, 10/08- PR14; 01/22- MR459 <br />generally downward concavity and have been found to range from 1,500 feet to 3,000 feet in <br />width. These systems may be made up of many channels or a single, meandering channel. If the <br />interface between sandstone and shale is a gentle slope, the affects on mining will be less than a <br />steeply inclined interface. An assessment of these roof conditions and cracks is contained in <br />Exhibit 16. Similar features are rare or absent in the B Seam. Although these channels may <br />cause roof problems, it should be pointed out that previous mining has been conducted safely and <br />effectively within West Elk Mine and in nearby mines. <br /> <br />Rolls <br /> <br />Rolls are a steep undulation on the mine floor that is greater than the regional dip. Rolls are <br />normally too small to be delineated from core hole data. Such structures could be present in any <br />seam in the West Elk Mine coal lease area. Anomalous dips in the F Seam in the Sylvester <br />Gulch indicated at least a minor roll with an apparent northeast trending axis. The degree of dip <br />of the B and E Seam is not constant and localized variations in the regional dip do occur, but <br />have little or no impact on mining. <br /> <br />Rock Spars <br /> <br />Rock spars are present in the West Elk Mine B Seam, the Bear Mine C Seam, the Somerset Mine <br />B and C Seams, and the Sanborn Creek Mine B Seam. They are generally vertical, up to four feet <br />in thickness and usually thinning upward. The spars are from a few feet to over a half-mile in <br />length. There has been no evidence from in-mine or core hole data of their presence in the F <br />Seam, or the E Seam. Clay dikes were observed in the B Seam test adit, on the north end of the <br />property, and spars have been encountered underground in the B Seam mine. Rock spars in the <br />E Seam are possible from the overlying sandstone channels but should be of limited thickness <br />and lateral extent. Little to no impact to mining is expected from the rock spars. <br /> <br />Seam Discontinuities <br /> <br />Seam discontinuities (i.e., rapid seam thinning due to non-deposition, channel cutouts, or <br />faulting) can occur anywhere in the coal lease area. Small faults (<10 feet displacement) have <br />been encountered in the F and B Seam workings. These have not caused any major problems <br />with the mining operation. Two fault systems were encountered in the southern E Seam main <br />entries with displacements of 20 to 70 feet. The southern panels, main entries and submains <br />were shortened and/or reoriented to be able to continue mining in those E Seam areas. <br /> <br />Soft Shales <br /> <br />Soft or weak shales in the roof, as discussed here, are local deposits usually related to the <br />presence of rooted or slickensided zones, and to the presence of carbonaceous debris within the <br />shales. Occurrences of these two phenomena are not predictable but they are usually associated <br />with and aggravated by sandstone channel margins. Slickenside zones and abundant <br />carbonaceous debris significantly contribute to overall weakening of the roof. In-mine <br />observation during the operation can help delineate these areas so that safe and adequate roof <br />control can be maintained. Areas of weak shale roof were widespread in the F Seam workings