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

Home Browse Search

West Elk Mine lineament or geotechnical evaluations of the surface lands. Furthermore, four other similar fault zones had previously been traversed in the B East and B West Mains without encountering significant water inflow. On April 8, 1996, MCC encountered the same fault in the #4 Entry (the next entry to the north). First-hand observations describe an initial flow in the main fault of less than 100 gpm from the back and ribs. Over a short period of time, the flow increased to several hundred gpm (rates similar to that in the #5 Entry). Simultaneous observations within the #5 Entry found that virtually all flow had ceased there. Approximately 30 minutes after first encountering the fault in the #4 Entry, a considerable increase in flaw occurred, predominately from the floor, with sufficient pressure to lift several blocks of floor coal several cubic feet in size. Based on visual observations and pumping capacities and piping required to keep up with the flow, the maximum flow from this fault zone was estimated to be 2,500 ±gpm. As with inflows from the #5 Entry, the flow from the #4 Entry began to diminish within three to four days. On May 7, 1996, the estimated flow rate from the fault was 240± gpm. Changes in the mine plan were initiated to avoid mining into the fault again in the remaining, down-dip entries. Development proceeded northward and east of the lONE Tailgate in order to develop a sump area prior to further attempts to cross the fault. With the sump constructed and pumping systems in place, the fault was again approached and traversed from the north (down dip direction) allowing fault water to drain from the faces into the sump. In May and early June 1996, MCC mined up to and through the fault in the #0 and #1 (northern most, down-dip) entries of the B East Mains only to find that no water was produced. Additionally, mining through the extension of the BEM Fault in the Box Canyon Mains produced very little water from all of the entries. This "hit-and-miss" encounter with water in the fault system indicates the difficulty in anticipating its presence. On June 20, 1996, MCC crossed the BEM Fault in the #2 Entry of the B East Mains. Within two weeks after mining through the #2 Entry, water was again encountered at a rate in excess of 1,000± gpm while flows in the #4 Entry ceased. Within 15 days this flow had diminished to approximately 120 gpm. By the middle of August 1996 the flow had decreased to approximately 85 gpm, exclusively through the #2 Entry. In July 1997, the BEM Fault inflow in the #2 entry dried as inflows began in the down- dip expression of this same fault system in the 145E Tailgate where about 200 gpm issued from the floor. In February 1998, the fault was again encountered producing about 200 gpm and drying up the flow in the 145E Tailgate. In May 2003, development mining crossed the fault in the 225E Headgate creating an initial inflow of 3,500 gpm but declined rapidly to about 200 gpm within 2 weeks. This fault system currently exists as a floor spring of approximately 120 gpm in the 225E Tailgate. • 1. Approximately 300 acre-feet of groundwater entered the mine via the BEM Fault in 1996. This represented an average of about 235 gpm from March 16 to December 31. 2.05-151 Revised June 1005 PR/0; Rev. March 2006; Rev. May 2006 PRIG