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West Elk Mrne <br />• In general, the calculation used to determine the "time to fill" for each area was as follows: <br />{[(panel area * 100%) + (development area * 50%)] * (mining height) * (50% void area)} / (inflow rate} <br />The calculated results for each azea include: <br />• F Seam workings (7 gpm) = 212.5 years <br />Example: [(69,696,000 ft.Zx50% from room and pillar mining)(6 ft)(50% void area)]/(491,872 ft.'/yr.) = 212.5 yrs <br />• Jumbo Mountain B Seam workings (7 gpm) = 253 years <br />Example: ([(17,005,000 ft Zx100%)+(7,475,000 ft Z)(50%)]*(12 ft)*(50%void area)} / (491,872 ft.3/yrJ =253.0 yrs <br />• Current (1996) B Seam workings (7 gpm) = 380 years <br />• Apache Rocks B Seam workings (7 gpm) = 821 years <br />• Apache Rocks E Seam workings (7 gpm) = 444 years <br />Cumulatively, if all mine workings were to fill at a sustained inflow rate of 7 gpm it would take <br />approximately 2,110 years (212+253+380+821+444); and if all mine workings were to fill at a <br />sustained inflow rate of 50 gpm (maximum instantaneous observation} it would take 295 years <br />(30+35+53+115+62). <br />• Because of unexpected inflows resulting from mining through water-bearing fault systems in 1996 <br />and the addition of the Box Canyon permit revision area (PROS), the "time to fill" calculations <br />were modified as were the estimates for probable and worst case groundwater inflows (see <br />Table 63) based on information presented in Table 2 of the 2004 Mayo aad Associates report <br />(Exhibit 18B). <br />Table 63 <br />Summary of Estimated Probable and Worst Case Groundwater Inflow to the Mine <br />1997 Estimate with 2004 u date <br /> Probable Maximum "Worst Case" Maximum <br />Item Inflows Inflows <br /> Initial Steady Initial Steady <br /> (GPM GPM GPM (GPM <br />B Seam, Life of Mine, Sloped 50 10 100 25 <br />Ent re-1996 <br />B Seam Life of Mine, Sloped 8,000 500 10,000 1,500 <br />Ent ost-1996 <br />E Seam Life of Mine, Sloped 1,700 200 5,100 600 <br />Entry (include South of <br />Divide minin area) <br />Much of the information and assumptions used in the revised "time to fill" calculatons have <br />remained the same, Those that have been modified since the 1994 estimate (for the Box Canyon <br />and SOD permit revisions) include: <br />• Approximate Apache Rocks Mining Area, including the three western and four eastern panels <br />(B Seam) - Longwall Panels (66,999,000 ft 1) and Development Areas (20,022,000 ft?) <br />1.05-211 Revised November 1004 PRIG <br />