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West Elk Mine <br />2. In rare cases, water can enter into mine workings through large scale regional fracturing <br />(when deeper mine workings are under fracture-controlled drainages, or the intersections of <br />fracture zones and drainages), or through faults. <br />It cannot be positively determined whether water encountered in the mine might be related to <br />fracture controlled valleys, unless a strong correlation can be mapped or quantified. Since the F <br />Seam is under the least amount of cover, chances of surface water, combined with shallow <br />overburden and/or major fractures, impacting mining operations would have been highest in the <br />F Seam. Underground mapping of miles of F Seam workings has shown a relationship between <br />shallow cover under drainages and poor roof conditions caused by water, but has not shown a <br />clear-cut relationship between fracture zones and wet roof conditions, with the exception of the <br />Sylvester Gulch entries. <br />Since the E Seam is deeper than the F Seam, it can be assumed that the effects of shallow <br />overburden and fracture related water on underground mining operations in the E Seam would <br />be less than in the F Seam, even though immediate roof rock sequences and types aze similaz. <br />The B Seam is deeper still, and seems to have more competent roof rocks than the E and F Seam, <br />so it can be assumed that neaz surface and fracture related water would have little impact on a <br />mining operation in the B Seam. Where depths of cover aze less, water may be encountered <br />beneath the more prominent drainages. <br />Groundwater in the inactive zone is ancient stored water residing in sand channel bodies, <br />. within the porous sections of fluvial or marine sand lenses, or within the damaged zones or <br />fault and fracture systems. The strata containing water surrounding the West Elk Mine <br />region has ancient water in the inactive zone that has been age dated to approximately 10,500 <br />years (A. Mayo, 1998). The residence time is consistent with similar non-tributary water <br />found in coal mines of the Wasatch Plateau and Book Cliffs of Utah. Melt-off of Pleistocene <br />glaciers from the West Elk Mountains south and east of MCC's coal lease holdings provided <br />an ample source of water of the appropriate age as the source for the inactive zone water. <br />In coal mines inactive zone inflows typically occur as: <br />1. Roof inflows from sandstone channels located in the lower portion of the Mesaverde <br />Group. Inflows from overlying sandstone channels issue from roof bolt holes, vertical <br />borings, or the bottoms of channels exposed during mining. <br />2. Floor inflows occurring as springs from shoreface and foreshore marine sandstones. <br />3. Roof and or floor inflows issuing from damage zones associated with faulting. These <br />damage zone inflows can significantly increase the inflow rates and total volumes of flows <br />associated with marine sandstone springs. In unusual circumstances minor amounts of <br />near surface (active zone) groundwater can enter the mine environment along fault <br />damage zone. <br />• The A through C Seam coal sequence is sandwiched between two large marine sandstone <br />bodies, the Rollins and Bowie Sandstones. These sands have moderate to good porosity at 5 <br />2.04-05 Revised November 1004 PRIO <br />