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West Elk Mrne <br /> <br />Table 62 <br />Summa of Estimated Probable and Worst Case Groundwater Inflow to the Mine 1994 Estimate <br /> Probable Maximum "Worst Case" Maximum <br /> Inflows Inflows <br />Item <br /> Initial Steady Initial Steady <br />F Seam, 5-Year Mine Plan <br />1991-1996 99 184 <br />Observed Inflow, F Seam <br />1982-1988 35 11.5 <br />Life of Mine Estimates 719 <br />• Approximate Apache Rocks Mining Area (E Seam) Longwall Panels (34,033,750 ft.Z) and <br />Development Areas (11,286,750 ft.Z) <br />• Approximate Jumbo Mountain Mining Area (B Seam) Longwall Panels (17,005,000 ft.z) and <br />Development Areas (7,475,000 ft,z) <br />• B and E Seam longwall mining panels are ] 00 percent open (panel areas defined above <br />represent the gross azea of longwall panel boundaries where all coal material were removed). <br />• B and E Seam development azeas are 50 percent open (development areas defined above <br />represent the gross azea of mains and development mining azound the longwall panels where <br />room-and-pillar mining where approximately half of the coal materials were removed). <br />• F Seam mining thickness (6 ft.) <br />• Approximate F Seam Mining Area is 2.5 mi.2 (69,696,000 ft.Z) <br />• F Seam Mitring Area is 50 percent open (F Seam mining was by the room-and-pillaz method <br />and a general assumption of 50 percent removal from these gross mining azeas was assumed). <br />• Half of the mining thickness is pore space following subsidence (i.e., only 50% of the volume <br />of coal materials removed is considered available to be filled by water because much of the <br />void space has been transferred vertically into the fractures and collapse areas above the mine <br />workings after mining). <br />• Average estimated sustained inflow into the combined B and F Seam mine workings (7 gpm) <br />or (491,872 ft 3/yr.) <br />• Average sustained inflow (1983-1995) observed into the mine (4.7 gpm, 7.54 AF/yr or <br />328,464.8 ft.3/yr.) <br />• Maximum observed inflow into the mine workings (50 gpm) or (3,513,369 ft.3/yr.) <br />• No seepage or outflow from the mine workings occurs. <br />In general, the calculation used to determine the "time to fill" for each area was as follows: <br />1.05-161 Revised June 2005 PRIO; Rev. March 1006; Rev, May 2006 PRIO <br />