Laserfiche WebLink
I'] <br />West Elk Mine <br />Spring flows are typically less than 10 gpm with annual discharge peaks in the spring which <br />generally diminish to no flow in the fall. <br />Mining of the B and F Seams to date has shown little groundwater inflow, except for the two <br />fault system inflows as noted above. The average rate of inflow between 1982 and 1995 had <br />been about 12 gpm, with a peak inflow rate estimated at 50 gpm in the B Seam and 10 gpm <br />in the F Seam. In 1996 this average inflow rate increased as a result of mining through the <br />BEM Fault to approximately 200 gpm. This is based on observed and measured inflows <br />from the fault system (approximately 235 gpm or 301 acre-feet over 291 days) and estimated <br />inflows similar to previous years (12 gpm) from other sections of the mine. In July 1997, the <br />fault inflow in B East Mains dried-up as inflows began in the down -dip expression of the <br />same fault system in the 14SE Tailgate. Inflows were initially about 200 gpm, but quickly <br />diminished to less than 100 gpm. <br />In January 1997, a second water -bearing fault system was encountered in the 14SE Headgate. <br />Initial inflows from the 14HG Fault were estimated in excess of 8,000 gpm (January 20, 1997) <br />dropping to 2,700 gpm by January 27, 1997 and to 1,750 gpm by January 31, 1997. By April <br />1997, inflows from the 14HG Fault had decreased to approximately 200 gpm. Similar to the <br />BEM Fault, in September 1998, when the 14HG Fault system was mined through in the 14SE <br />Tailgate, the headgate inflow dried-up and the inflow began in the tailgate entries along the <br />down -dip expression of the fault. Total 1997 inflows from the BEM Fault were approximately <br />161 acre feet and from the 14HG Fault were approximately 504 acre feet. In 2002, the total <br />inflows from these two fault systems were estimated to be 129 acre feet. <br />• Groundwater inflows, other than those associated with the fault systems described above, <br />are primarily observed near portal areas under low cover (less than 300 feet) near drainages and <br />are generally responsive to spring runoff <br />• Available data demonstrate that there has not been a measurable impact on springs or <br />surface water strictly attributable to F and/or B Seam mining <br />• Groundwater levels in well SOM 38-H-1 have been observed to decrease directly as a result of <br />F Seam retreat mining, but recovered to pre -mining levels following panel subsidence <br />In 1994, CDMG approved a permit revision (Jumbo Mountain PR05) for the West Elk Mine. Much <br />of the information contained in the Jumbo Mountain Decision Document (CDMG 1994) regarding <br />the current permit area is directly applicable to the probable hydrologic consequences anticipated as <br />a result of mining the Apache Rocks and Box Canyon permit revision areas. <br />The following quotations from the Jumbo Mountain (PR05) Decision Docunent apply to the <br />current permit area, including the Apache Rocks and Box Canyon perr_nit revision areas. WWE <br />connnnents are included on the relevancy of the quotations for the Apache Rocks and Box Canyon <br />permit revision areas. <br />2.05-176 Revised June 2005 PRIO, January 2006. March 2006; Rev. Mqy 2006 PRIG. Nov. 2006 TRIO 7; Sep. 2007 PR12; Feb 2008 PRI2 <br />