REP14668 - Laserfiche WebLink

Home Browse Search

• 1999 Production and Geologic Conditions The Bowie No. I Mine suspended operations during December,1997 and remained idle throughout the 1999 calendar year. Operation Uoit Descriptions Bowie No. 1 Mine has no operating units to report on during the 1999 calendar year Subsidence Impacts - 1999 Subsidence survey monitoring of selected wide-spaced monuments in the vicinity of active mine workings was conducted during June, 1999 and September, 1999. Surveying of these selected stations was conducted in accordance with the projected monitoring addressed in the 1998 Annual Subsidence Report. Selected subsidence monitoring stations established over the Pitkin Mesa pipeline were monitored in June and September of 1999. Wide-Spaced Monitoring Grid Station Summary Fourteen wide-spaced monitoring grid stations were surveyed for the 1999 reporting yeaz. The station locations aze shown on Map No. 2-5. The following discussions present a station by station assessment of survey results generated for 1999. Monitoring station data sheets are appended to this report for reference. Station 6 Surveys were initiated in August 1982 and continued biannually through July • 1984. Surveys were re-initiated in 1987 and conducted annually through 1991 and biannually 1992 - 1994. Station 6 is located on approximately 350 feet of overburden and lies approximately 300 feet north of [he 1st North, 2 %z West Panel retreat mined from May through June, 1983. Station 6 lies adjacent to the II West Submain development advanced in 1987. The 1999 survey data indicates an elevation loss of 0.07 feet when compazed to the November 1998 elevation. Station 6 is located within a mapped landslide area and may be exhibiting movement associated with this feature. No mining anticipated to produce subsidence has occurred in the vicinity of Station 6 since 1983. Station 14 Station 14 is located in the Stevens Gulch alluvium protective buffer zone over approximately 750 feet of overburden. The station was initially surveyed in June, 1982. Subsequent surveys have been conducted annually since 1988. Panel G was advanced under this station in September, 1988. Retreat mining occurred outside the buffer zone in the vicinity of this site in February, 1989. Panel C was advanced adjacent to this site in December, 1992. An elevation adjustment of- 0.55 feet was detected at this site in October 1989 but was perhaps influenced by control station coordinates being redefined. January 1991 data indicated 0.31 feet were subsequently gained but again, new control point coordinates were generated. No mining activity took place in the vicinity of station l4 during 1999. The 1999 survey results show an elevation loss of 0.13 feet when compared to the November 1998 elevation. • -l-