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1998 Production and Geologic Conditions • <br />The Bowie No. I Mine suspended operations during December,1997 and remained idle <br />throughout the 1998 calendar year. <br />Operation Unit Descriptions <br />Bowie No. I Mine has no operating units to report on during the 1998 calendar year <br />Subsidence Impacts - 1997 <br />Subsidence survey monitoring of selected wide-spaced monuments in the vicinity of active mine <br />workings was conducted during July, 1998 and November, 1998. Sttrveying of these selected <br />stations was conducted in accordance with the projected monitoring addressed in the ]997 <br />Annual Subsidence Report. Selected subsidence monitoring stations established over the Pitkin <br />Mesa pipeline were monitored in July and November of 1998. <br />Wide-Spaced Monitoring Grid Station Summary <br />Fourteen wide-spaced monitoring grid stations were surveyed for the 1998 reporting year. The <br />station locations are shown on Map No. 2-5. The following discussions present a station by <br />station assessment of survey results generated for 1998. Monitoring station data sheets are <br />appended to this report for reference (Tab 7). <br />Station 6 Surveys were initiated in August 1982 and continued biannually through July <br />1984. Surveys were re-initiated in 1987 and conducted annually through 1991 and • <br />biannually 1992 - 1994. Station 6 is located on approximately 350 feet of <br />overburden and lies approximately 300 feet north of the 1st North, 2 '/: West Panel <br />retreat mined from May through June, 1983. Station 6 lies adjacent to the II West <br />Submain development advanced in 1987. The 1998 average survey data indicates <br />an elevation gain of 0.04 feet. Station 6 is located within a mapped landslide area <br />and maybe exinbiting movement associated with this feature. No mining <br />anticipated to produce subsidence has occurred in the vicinity of Station 6 since <br />1983. <br />Station 14 Station 14 is located in the Stevens Gulch alluvium protective buffer zone over <br />approximately 750 feet of overburden. The station was initially surveyed in June, <br />1982. Subsequent surveys have been conducted annually since 1988. Panel G was <br />advanced under this station in September, 1988. Retreat mining occurred outside <br />the buffer zone m the vicinity of this site in February, 1989. Panel C was advanced <br />adjacent to this site in December, 1992. An elevation adjustment of-0.55 feet was <br />detected at this site in October 1989 but was perhaps influenced by control station <br />coord'mates being redefined. January 1991 data indicated 0.31 feet were <br />subsequently gained but again, new control point coordinates were generated No <br />mining acti,~ty took puce in the vicinity of station 14 during 1998, The July 1998 <br />measurements were within the historic maximum and m;nimnm elevation values for <br />this station. <br />-1- <br />C J <br />