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West E(k Mine <br />~. 1. "The most continuous sandstone aquifers of any significance in the region are the Rollins <br />Sandstone and the Marine Sandstones sepazating 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. hi addition, the <br />Rollins Sandstone has been found to have insufficient yield to sustain groundwater supply <br />wells. In the Jumbo Mountain azea, the Rollins Sandstone appeazs to be hydraulically <br />isolated." (p. 19). <br />This conclusion applies without modification to the entire permit azea, except that the word <br />"aquifer" should be replaced with "formation." Per Bates and Jacobson (1987), an aquifer is <br />defined as "a body of rock that is sufficiently permeable to conduct groundwater and yield <br />economically significant quantities of water to wells or springs." Freeze and Cherry (1979), in the <br />well-known reference Groundwater, define an aquifer as "a saturated permeable geologic unit that <br />can transmit significant quantities of water under ordinary gradients." The geologic formations <br />located in the vicinity of the West Elk Mine do not meet either ofl these definitions. Petrographic <br />analyses have revealed that the sandstones in the Rollins Sandstone aze depositionally immature <br />(Mayo 1998) and have low permeabilities, making the Rolling Sandstone an effective barrier to <br />groundwater flow. The only significant inflows to the mine have been associated with fault and <br />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 <br />55 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 <br />about 0.75 gpm." (p. 20). <br />In the Apache Rocks and Box Canyon pemut revision areas, approximately 15 and 8 boreholes, <br />respectively, have been constructed. Cazeful 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. "When faults and fractures aze encountered within the mines of the North Fork region, they <br />generally produce mine inflows. The flow characteristics of each mine inflow associated with <br />faults and fractures depend upon the lateral extent and the proximity of the fault or fracture to a <br />stream valley. All inflows from these water sources aze characterized by an initial surge of <br />. water which then either decreases or ceases completely with time." (p. 20). <br />I <br />1.05-141 November 1004 PRI / <br />