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' Mayo and Associates, LC <br />• Formation and Rollins Sandstone Member. In unusual circumstances <br />minor amounts of active zone groundwater enters the mine environment. <br />I The cross-sectional relationships between potential groundwater-bearing sandstone <br />' bodies aze illustrated in Figure 5. <br />I 2.3 Properties of sandstone bodies with and without fractures <br />' The hydraulic conductivity of unfractured shale and sandstone bodies in the lower <br />Mesaverde Group aze listed in Table 1. Analyses include sandstone channels and <br />' intervening silt and shale of the Blackhawk Formation, various members of the Star Point <br />' Sandstone, and the Rollins Sandstone. Hydraulic conductivity is a measure of the ability <br />' • of water to move through the matrix of rock without fracture flow. Most measurements <br />are for horizontal conductivity. Blackhawk shale values of 10-5 to 10-6 ft day' indicate <br />that the shale is relatively impermeable. Although the data are Iimited, vertical <br />' conductivities are less than horizontal, which is typical of most sedimentary rock. What <br />this means is that water flows more readily pazallel to bedding surfaces than it flows <br />' vertically between bedrock layers. <br />Typical values of the sandstone channels and Star Point and Rollins beach sandstones are <br />' 10-z to 10~t ft day t. These values are greater than the mudstones in the lower Mesaverde <br />' Group and aze adequate to transmit water in unfractured rock. What this means is that, in <br />the absence of opera fractures, only sandstone bodies (i.e., sandstone channels or shoreline <br />~. sandstones) aze capable of transmitting appreciable groundwater to mine workings. In <br />Evaluation of Potential Groundwater Inflows 19 February 24, 2004 <br />Associated with E Seam Mining, <br />' West Elk Mine, Somerset, Colorado <br />