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West Elk Mine <br />mining crossed the fault in the 22SE Headgate creating an initial inflow of 3,500 gpm <br />but declined rapidly to about 200 gpm within 2 weeks. This fault system currently <br />exists as a floor spring of approximately 120 gpm in the 22SE Tailgate. <br />• Approximately 300 acre-feet of groundwater entered the mine via the BEM Fault in <br />1996. This represented an average of about 235 gpm from March 16 to December 31. <br />From mid-November 1996 through 2003 the inflows maintained a relatively constant <br />inflow rate of about 80 gpm. Assuming that the rest of the mine had inflows similar to <br />previous years (i.e., 12 gpm or 19 acre-feet per year), the cumulative inflows to the mine <br />from groundwater in 1996 totaled approximately 320 acre-feet (averaged over the year, <br />this is equivalent to about 200 gpm). MCC knows of no detrimental impacts to <br />groundwater users in the region due to claimed reliance on this groundwater. <br />2. l4SE Headgate Fault (a.k.a. 14HG Fault) - In mid-January 1997, white development <br />mining the #3 entry near cross-cut #11 of the 14SE Panel Headgate, a southwest to <br />northeast-trending fault (similar in orientation to the BEM Fault) was encountered <br />which produced approximately 100 gpm, primarily from the floor. On January 20, <br />1997, development mining was occurring in the #2 Entry between cross-cut #10 and #11 <br />when a massive inflow of more than 8,000 gpm entered the mine from the floor with <br />enough force to lift the water to the roof. The water temperature was approximately <br />88°F. The inflow dropped to approximately 2,700 gpm within a week and to 1,750 gpm <br />a few days later. By April 1997, inflows from the 14HG Fault system had decreased to <br />approximately 200 gpm. Similar to the BEM fault system, in September 1998 when the <br />14HG Fault system was mined through in the 14SE Tailgate, the hadgate inflow dried <br />and the inflow began in the tailgate entries. In August 2003, development mining <br />penetrated the 14HG Fault at cross-cut #32 of the 22SE Headgate producing an initial <br />inflow rate of about 100 gpm that rapidly declined to approximately 35 gpm. <br />Until the spring of 1996, when the BEM Fault system was encountered, there had been no reason <br />to plan for the managing of large mine groundwater inflows. With the unexpected production of <br />several thousand gallons of water from both the BEM and 14HG fault systems in the B Seam <br />workings, the need for more rigorous water management and planning had azisen. MCC has <br />worked proactively to ensure that unexpected mine inflows can be managed without <br />compromising safety, operations or environmental requirements. Examples of the proactive <br />efforts undertaken at that time, and still in place today, include: <br />• Utilizing previously-mined down-dip areas as lazge capacity sumps. The NW and NE Panels <br />sealed sumps have historically been used for this purpose (see discussion later in this <br />section). <br />• Development mining has proceeded in a measured and cautious manner in the eastern portion <br />of the B Seam mine workings. Mining plans have been revised and developed to include <br />procedures for the encounter of additional water-bearing faults. As a result, MCC is <br />prepared to mobilize rapidly to control additional groundwater inflows should they <br />occur. <br /> <br />1.05.211 RevisedNwember 2004 PRIG <br />