2008-03-31_PERMIT FILE - C1980007A (34)

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West Elk Mine 2003 and will be ongoing to provide baseline and operational water level data for the South of Divide area. E Seam mining in the South of Divide permit revision area will occur between 375 feet and approximately 1,200 feet below the alluvial materials associated with the Dry Fork of Minnesota Creek. As previously stated, the alluvial materials are part of the surface and near- surface active groundwater regime in the Dry Fork drainage and thus in direct hydraulic communication with seasonal and climatic events. This is in contrast to the E Seam groundwater, which is part of the inactive groundwater zone, which does not have direct hydrologic communication with the near-surface groundwater system within the Dry Fork drainage. Permeability and Factors Influencing Penneability Table 5 and Table 6 summarize the available permeability data for the mine property obtained from pumping and slug tests. Most of the permeability information has been presented previously in F Seam permit applications. However, two slug tests of B Seam wells were performed by GeoWest personnel in October 1988 (Exhibit 17) and laboratory permeability analyses were performed on core plugs obtained from the lower Mesaverde Formation and the Rollins Sandstone per Mayo and Associates (1998). In general, it can be stated that the alluvium and colluviuin are more permeable than the bedrock units and that the uppermost bedrock units are more permeable than those at depth. The permeability of the alluvium is approximately 1 x 10-6 cm/sec to 1 x 10-4 cm/sec. The slug and pumping tests provide a measure of horizontal permeability. Vertical penneability is typically at least a factor of three to five tunes lower than horizontal permeability. A major factor that influences permeability of the bedrock at the site is jointing (and other fracture discontinuities) and faulting. To clarify, fractures differ from faults in that fractures have no relative offset across fracture planes. The location of fractures and faults within the bedrock is sometimes difficult to assess particularly if bedrock units are poorly exposed or if there is minimal offset at the surface. As a result, significant linear features can be mapped as an initial means to assess potential faulting and fracturing of the bedrock formations. Site- specific evaluation of exposed bedrock outcrops are used to assess joint spacing and openings (apertures). Major lineaments (longer than 2,000 feet in length) are shown on Map 24. Several drainages within the property appear to be fracture controlled. Although not evident from aerial photos, the North Fork most likely represents a major fracture zone. Johiting can be observed in the steep cliff outcrops along the North Fork and springs are occasionally seen discharging from the joints. The hydrologic investigations conducted by MCC have shown that most springs on the property discharge near or above the F Seam. This indicates the fracture zones are tighter or have not propagated through shale seams below the F Seam to the same extent as above the F Seam. As discussed previously in Section 2.04.7, there are a few springs discharging between the F and E Seams and little indication of groundwater discharge below that level. There is little data available for joint spacing or aperture at the site. MCC collected a limited amount of joint mapping information in 1973-1974. The three major joint orientations at the site are E-W with a 90E dip or slight eastward dip, N-S with 90E or slight eastward dip and N 50E with a 90E dip. The shallowest dip measured as part of this study was 71E. Joint spacing measured in 2.04-71 Revised June 2005 PR10, March 2006; Rev. Apri12006 PR10, Sep. 2007PR12