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Mayo and Associates, LC <br /> <br />Formation and Rollins Sandstone Member. In unusual circumstances <br />minor amounts of active zone groundwater enters the mine environment. <br />~• <br />'~ <br /> <br />The cross-sectional relationships between potential groundwater-bearing sandstone <br />bodies aze illustrated in Figure 5. <br />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 Staz 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 t indicate <br />that the shale is relatively impermeable. Although the data are limited, vertical <br />conductivities aze less than horizontal, which is typical of most sedimentary rock. What <br />this means is that water flows more readily parallel 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 aze <br />10-2 to 10-t ft day ~. These values are greater than the mudstones in the tower Mesaverde <br />Group and are adequate to transmit water in unfractured rock. What this means is that, in <br />the absence of open 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 />