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• 1994 Subsidence Report <br />Page 3 <br />Anomalous Conditions: <br />Small seeps from both roof and floor sources were encountered <br />throughout development of the section. <br />Subsidence Eaq~acts 1994 <br />Subsidence survey monitoring of selected wide-spaced tronu~nts in the vicinity <br />of active mine workings was conducted during May, September and October of 1994. <br />Surveying of these selected stations was conducted in accordance with the <br />projected monitoring addressed in the 1993 Annual Subsidence Report. Selected <br />subsidence mronitoring stations established over the Pitkin Mesa Pipeline were <br />monitored in May and September, 1994. <br />Wide-Spaced Monitoring Grid Station Sumnarv <br />Fourteen wide-spaced tronitoring grid stations were surveyed for the 1994 <br />reporting year. The station locations are shown on Map No. 2-5. The following <br />discussions present a station by station assessment of survey results generated <br />for 1994. hbnitoring station data sheets aze appended to this report for <br />reference. <br />Station 6: Surveys were initiated in August 1982 and continued <br />• biannually through July 1984. Surveys were re-initiated in <br />1987 and conducted annually through 1991 and bi-annually 1992 <br />- 1994. Station 6 is located on approximately 350 feet of <br />overburden and lies approximately 300 feet north of the 1st <br />North, 2 1/2 West panel retreat mined from May through June, <br />1983. Station 6 lies adjacent to the iI West Sulinain <br />development advanced in 1987. May 1994 survey data indicates <br />an elevation loss of 0.36 feet and the September 1994 survey <br />data indicates an elevation gain of 0.23 feet with both <br />elevation measurements within the previously established <br />range of measurement documented at this site. Station 6 is <br />located within a mapped landslide area and may be exhibiting <br />movet~nt associated with this feature. No mining anticipated <br />to produce subsidence has occurred in the vicinity of Station <br />6 since 1983. <br />Station 14: Station 14 is located in the Stevens Gulch alluvium <br />protective buffer zone over approximately 750 feet of <br />overburden. The station was initially surveyed in June, <br />1982. Subsequent surveys have been conducted annually since <br />1988. The September 1994 data indicates the station has seen <br />an overall increase in elevation totalling 0.98 feet. Panel <br />G was advanced under this station in September, 1988. <br />Retreat mining occurred outside the buffer zone in the <br />vicinity of this site in February, 1969. Panel C was <br />advanced adjacent to this site in December, 1992. An <br />• elevation adjustment of -0.55 feet was detected at this site <br />in October, 1989 but was perhaps influenced by control <br />station coordinates being redefined. January 1991 data <br />