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West Elk Mine <br />. 2. "Observations made underground by the staff of the Division at mines in the region showed that <br />the coal seams are poor aquifers with very low transmissivities." (p. 4). <br />3. "Fracturing improves the water -bearing qualities of the discontinuous sandstones and shales <br />overlying the mines. Some fractures and faults transect the Mesaverde Formation and extend <br />vertically to the surface. These faults and fractures produce narrow bands of secondary porosity <br />within the rock strata. Due to the low permeability of the rock strata within the Mesaverde <br />Formation, these faults and fractures provide the primary path through which water flows both <br />vertically between rock strata and horizontally within rock strata." (p. 4). <br />This statement is generally true, except that in the eastern portion of West Elk Mine (B East <br />Mains and 14SE Headgate) a fracture/fault system was of sufficient size and storage capacity to <br />generate initial inflow rates of approximately 2,500 and 8,000 gpm, respectively. As is typical <br />of fracture -controlled reservoirs in the oil industry, and as MCC has experienced with other <br />inflows in the mine, these inflows reduced to a fraction of the initial inflow rates within a few <br />months (to 80 gpm in the case of the BEM Fault, which is about 3 percent of the initial flow <br />rate). The 14HG Fault inflow also reduced to less than 3 percent of the initial inflow rate of <br />8,000 gpm. <br />It is important to contrast the amount and nature of surface cracking associated with longwall <br />mining versus room -and -pillar mining. Based upon careful field inspections of the ground <br />surface above West Elk Mine's 1NW through 7NW longwall panels, Mr. Dunrud has <br />• determined that longwall mining in this setting produces very few surface cracks, and that when <br />cracks do appear, they are located only in areas of maximum stress and are likely to "seal" <br />themselves. Detailed discussion regarding the frequency ("risk") of surface cracks based upon <br />inspection of these panels is provided in Section 2.05.6, Surface Water Quantity Effects, <br />Streams. This section concludes that the probability of any given channel in the South of Divide <br />permit revision areas encountering a crack is 0.2 percent, (see calculations in discussion entitled <br />Analysis of Impacts to Streams) and that the total annual loss of surface flow to cracks will be of <br />no practical significance. <br />• <br />4. "Inflows from faults and fractures located outside stream valleys, such as in the Bowie No. 1 <br />Mine, generally dry up with .time or flow intermittently at discrete points along the fault or <br />fracture, with the exception of the most recently encountered Nest Elk Mine inflows. <br />Those which continue to flow, have flow rates which diminish to a trickle. Such inflows may <br />represent the dewatering of lenticular sandstone units with limited recharge areas or may <br />represent flows through fracture zones extending to the surface which have nai•rov-.recharge <br />zones on steep slopes." (p. 5). <br />In every case, inflows have rapidly diminished to a fraction of the initial iiiflo�vs of iii ,many <br />cases have ceased entirely. In the cases of the BEM Fault and the 14HG Fault; inflows <br />T. I„nn 1 <br />eiicoi:uit�rcu iii l��iai_-_�t- -ii 1776 alio 3ailuaiy 1997, respectively, the inflows <br />percent of the maximum observed inflow rates after a few months. <br />2.05-181 Revised June 2005 PRIO, January 2006, March 2006; Rev. May 2006 PR10, Nov. 2006 TR107; Sep. 2007 PR12: Feb 2008 PR12 <br />