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West Elk Mine <br />elevation of the mine opening are drained. The inflows from the faults reach equilibrium <br />at 50 to 125 gpm, existing as floor springs until the fault zone is breached at a lower <br />elevation by subsequent development. Down-dip inflow rates from the fault zones are <br />dependent upon the displacement and damage zone extents, the incremental head (vertical <br />elevation change), and linear distance from the last fault intercept. Each new down-dip <br />intercept dries up the previous floor spring. Up-dip inflows from the faults have been <br />limited to short-lived nuisance roof water at less than 10 gpm, with no sustained water <br />flows from the faults. <br />Since 1996 four significant inflows (>2,000 gpm) from two major fault systems have been <br />encountered in the B Seam mining. The first fault inflow from the B East Mains Fault (BEM) <br />initially produced more than 2,000 gpm in the spring of 1996. The flow rate steadily <br />diminished to a rate of approximately 85 gpm, and then ceased when the same fault system was <br />encountered to the northeast in the 14 Tailgate in eazly July 1997. Flow at this intercept was <br />initially about 200 gpm, which diminished to less than 100 gpm. The BEM Fault Zone was <br />again encountered down-dip in 22HG with an initial flow rate of 3,500 gpm, declining to <br />200 gpm within two weeks. Encountered down-dip once more in 22TG, the initial flow was <br />3,000 gpm, declining to 370 gpm within one week and 200 gpm within two weeks. The fault <br />water currently exists as a floor spring of approximately 120 gpm. Amore thorough <br />discussion of this unprecedented B East Mains fault inflow can be found in Section 2.05.6(3). <br />The second fault (known as the 14 Headgate fault) had an initial estimated inflow rate of <br />approximately 8,000 gpm when encountered on January 20, 1997. Subsequent intercepts in <br />14TG and 22HG on the down-dip extension of the fault zone yielded water inflows up to <br />200 gpm. The differences in initial flow rates can be attributed to the diminishing fault <br />offset to the north in 22HG (reduced storability) and increasing offset to the south <br />(increased storability) from the initial intercept in 14HG. At 14HG the total displacement <br />on the zone is 11 Feet. Going northeast, the 14HG Fault Zone displacement decreases to 8 <br />feet in 14TG, 1 foot in 22HG, and mere inches in 22TG. Southeast along the same system, <br />displacement increases from 8 feet in 14HG to 15 feet in 15HG, 18 feet in 16HG, 22 feet in B <br />South Mains, and 15 feet again in 13A HG. The overall relationship between fault offset <br />and damage zone water storage and inflow rates becomes obvious. Given these mine <br />previous inflows, MCC believes that similar conditions may exist in future mining areas <br />and has developed water handling systems within the mine to manage potential large- <br />volume future inflows (See 2.05 Operations Plan, Hydrologic Protection During Operations, <br />and Exhibit 69). <br />E Seam mining will encounter many of the same fault systems and possibly two inferred zones <br />not intercepted in the B Seam. Mayo (2004) projects the previously intercepted fault zones may <br />have insignificant nuisance waters associated with the fault zones and anticipated inflows from <br />either Rollins or Bowie sandstones will be small or non-existent. The exception may be where <br />tectonic faults have crossed sandstone roof channels, allowing the channel and fracture damage <br />zones to store water. Inflows from the sandstone channels may reach 500 gpm in that instance. <br />Inflows into the E Seam mine workings may reach 2,000 gpm from un-intercepted tectonic <br />faults. This value reflects possible damage zone widths, distance to outcrop, and vertical <br />elevation. <br />2.04-47 Revised November 2004 PRI G <br />