2022-09-29_PERMIT FILE - C1980007 (2)

Home Browse Search

West Elk Mine {[(panel area * 100%) + (development area = 50%)] • (mining height) * (50% void area)} / (inflow rate} The calculated results for each area include: • F Seam workings (7 gpm) = 212.5 yeazs Example: [(69,696,000 ft Z)(50% from room and pillar mining)(6 ft)(50% void area)]/(491,872 R.'/yr.) = 212.5 yrs • Jumbo Mountain B Seam workings (7 gpm) = 253 years Example: {[(17,005,000 ft.2)(100%)+(7,475,000 ft.Z)(50%)]+(12 ft)*(50%void area)} / (491,872 ft.3/yr.) = 253.0 yrs • Current (1996) B Seam workings (7 gpm) = 380 years • Apache Rocks B Seam workings (7 gpm) = 821 yeazs • Apache Rocks E Seam workings (7 gpm) = 444 years Cumulatively, if all mine workings were to fill at a sustained inflow rate of 7 gpm it would take approximately 2,110 yeazs (212+253+380+g2]+444); and if all mine workings were to fill at a sustained inflow rate of 50 gpm (maximum instantaneous observation) it would take 295 years (30+35+53+115+62). Because of unexpected inflows resulting from mining through water-bearing fault systems in 1996 and the addition of the Box Canyon permit revision azea (PR08), the "time to £dl" calculations were modified as were the estimates for probable and worst case groundwater inflows {see Table 63) based on information presented in Table 2 of the 2004 Mayo and Associates report (Exhibit 18B). Table 63 Summary of Estimated Probable and Worst Case Groundwater Inflow to the Mine 1997 Estimate with 2004 u date Probable Maximum "Worst Case" Maximum Item Inflows Inflows Initial Steady Initial Steady GPM (GPM (GPM (GPM) B Seam, Life of Mine, Sloped 50 10 100 25 Ent re-1996 B Seam Life of Mine, Sloped 8,000 500 10,000 1,500 Ent st-1996 E Seam Life of Mine, Sloped 1,700 200 5,100 600 Entry (include South of Divide minin area G 2.05-262 Revised June 2005 PRIO; Rev. March 2006; Rev. May 1006 PRIG