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West Elk Mine I. ~. 2. "Observations made underground by the staff of the Division at mines in the region showed that the coal seams aze poor aquifers with very low transmissivities." (p. 7). 3. "Fracturing only minimally improves the water bearing qualities of the discontinuous sandstones and shales overlying the mines. Some fractures and faults transect the Mesaverde Formation and extend vertically to the surface. These faults and fractures produce narrow bands of secondary porosity within the rock strata. Due to the low permeability of the rock strata within the Mesaverde Formation, these faults and fractures provide the primary path through which water flows both vertically between rock straw and horizontally within rock strata." (p. 7). This statement is generally true, except that in the eastern portion of the West Elk Mine (B East Mains and 14SE Headgate) afracture/fault system was of sufficient size and storage capacity to generate initial inflow rates of approximately 2,500 and 8,000 gpna, respectively. As is typical of fracture-controlled reservoirs in the oil industry and as MCC has experienced with other inflows in the mine, these inflows reduced to a fraction of the initial inflow rates over time - 80 gpm in the case of the B East Mains Fault, which is about 3 percent of the initial flow rate. The 14SE Headgate inflow also reduced to less than 3 percent of the initial It is important to contrast the amount and nature of surface cra mining versus room-and-pillaz mining. Based upon cazeful fieldu above the West Elk Mine's 1NW through 7NW longwall panels, ] longwall mining in this setting produces very few surface cracks, they aze located only in areas of maximum stress and aze likely discussion regarding the frequency.("risk") of surface cracks based is provided in Section 2.05.6, Surface Water Quantity Effects, Strec the probability of any given channel in the Apache Rocks and Bc encountering a crack is 0.2 percent, (see calculations in discussion Streams) and that the total annual loss of surface flow to cracks will rate of 8,000 gpm. :king associated with longwall spections of the ground surface ~Ir. Dunrud has determined that nd that when cracks do appeaz, :o "seal" themselves. Detailed upon inspection of these panels ms. This section concludes that ~ Canyon permit revision azeas entitled Analysis of Impacts to be of no practical significance. 4. "Inflows from faults and fractures located outside stream valleys generally dry up with time or flow intermittently at discrete points along the fault or fracture'. Those which continue to flow have flow rates which diminish to a trickle. Such inflows may represent the de-watering of lenticulaz sandstone units with limited recharge areas or may 'represent flows through fracture zones extending to the surface which have narrow rechazge zonies on steep slopes." (p. 8). In every case, inflows have rapidly diminished to a fraction of the initial inflows or in many cases have ceased entirely. In the cases of the B East Mains fault and the 14SE Headgate fault, inflows encountered in March 1996 and January 1997, respectively, the inflows decreased to about 3 percent of the maximum observed inflow rates after a few months. 5. "Preliminary aquifer tests were performed by Mountain Coal Company...and they indicate that the F-Seam and lenticulaz sandstones of the Barren Member are poor aquifers at best, as groundwater flow is mainly concentrated in fractured rock." (p. 8). 1.05-145 November 1004 PRI /