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0- <br />West Elk Mine <br />1. "The most continuous sandstone aquifers of any significance in the region are the Rollins <br />Sandstone and the Marine Sandstones separating the Upper and Lower Coal Members of the <br />Mesaverde Formation. The Marine Sandstones produce very little water, as evidenced by the <br />dryness of the Bear Mine and the lack of springs associated with this unit. In addition, the <br />Rollins Sandstone has been found to have insufficient yield to sustain groundwater supply <br />wells. In the Jumbo Mountain area, the Rollins Sandstone appears to be hydraulically <br />isolated." (p. 19). <br />This conclusion applies without modification to the entire permit area, except that the word <br />"aquifer" should be replaced with "formation." Per Bates and Jacobson (1987), an aquifer is defined <br />as "a body of rock that is sufficiently permeable to conduct groundwater and yield economically <br />significant quantities of water to wells or springs." Freeze and Cherry (1979), in the well-known <br />reference Groundwater, define an aquifer as "a saturated permeable geologic unit that can transmit <br />significant quantities of water under ordinary gradients." The geologic formations located in the <br />vicinity of the West Elk Mine do not meet either of these definitions. Petrographic analyses have <br />revealed that the sandstones in the Rollins Sandstone are depositionally immature (Mayo 1998) and <br />have low permeabilities, making the Rolling Sandstone an effective barrier to groundwater flow. <br />The only significant inflows to the mine have been associated with fault and fracture systems. <br />2. "The alluvium along the lower reaches of tributaries to the North Fork of the Gunnison River is <br />predominantly thin and confined to discontinuous narrow bands along the stream courses. The <br />deeply incised channels of these tributaries restrict the width of the alluvium, while the stream <br />gradient and the presence of resistant sandstone in the stream channels limit the thickness and <br />downstream extent of the alluvium." (p.19). <br />WWE's field inspection of the drainages confirms this statement. See Section 2.04.7 and Exhibit 55 <br />for more detail on the nature of the channels/alluvium. <br />3. "The laterally discontinuous lenticular sandstones within the upper Mesaverde Formation <br />support only localized groundwater flows. Of 112 exploration drill holes at the West Elk Mine <br />that were drilled prior to the mine opening, only 3 of the holes produced water from the F -Seam <br />at a production rate of 3 gpm or less. Three other holes in the Barren Member had rates of about <br />0.75 gpm." (p. 20). <br />T <br />n the Apache Rocks and Box Canyon permit revision areas, approximately 15 and 8 boreholes, <br />respectively, have been constructed. Careful review of the drilling logs indicate that very few of <br />these holes encountered measurable inflows of water at the time of construction. <br />4. "W'hen faults and fractures are encountered within the mines of the North Fork region, they <br />generally produce mine inflows. The flow characteristics of each aline inflow associated with <br />faults and fractures depend upon the lateral extent and tl-,e prG.-Ki. ii y _ _.__ __ult or fracture to a <br />stream -\,„alley. All inflows from these water sources are characterized by an initial surge of <br />waterwhichthen either decreases or ceases completely with tinge.” (p. 20). <br />2.05-177 <br />Revised June 2005 PRIG, January 2006, March 2006; Rev. May 2006 PRIG. Nov. 2006 TR107:Sep. 2007PR12;Feb 2008 PR12 <br />