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Wide-Spaced Monitoring Grid Station Summarx <br />Fourteen wide-spaced monitoring grid stations were surveyed for the 1996 reporting <br />year. The station locations are shown on Map No. 2-5. The following discussions <br />present a station by station assessment of survey results generated for 1996. <br />Monitoring station data sheets are appended to this report for reference (Tab 7). <br />Station 6: Surveys were initiated in August 1982 and contimied biannually <br />tluough July 1984. Surveys were re-initiated in 1987 and conducted <br />annually through 1991 and bi-annually 1992 - 1994. Station 6 is <br />located on approximately 350 feet of overburden and lies <br />approximately 300 feet north of the 15` North, 2 % West panel retreat <br />mined from May through June, 1983. Station 6 lies adjacent to the R <br />West Submain development advanced in 1987. The 1996 average <br />survey data indicates an elevation gain 0.04 feet. Station 6 is located <br />within a mapped landslide area and may be exhibiting movement <br />associated with this feariire. No mining anticipated to produce <br />subsidence has occurred in the vicinity of Station 6 since 1983. <br />• Station 14: Station 14 is located in the Stevens Gulch alluvium protective buffer <br />zone over approximately 750 feet of overburden. The station was <br />initially surveyed in June, 1982. Subsequent surveys have been <br />conducted annually since 1988. Panel G was advanced under this <br />station in September, 1988. Retreat mining occurred outside the buffer <br />zone in the vicinity of this site in Febn~ary, 1989. Panel C was <br />advanced adjacent to this site in December, 1992. An elevation <br />adjustment of -0.55 feet was detected at this site in October 1989 but <br />was perhaps influenced by control station coordinates being redefined. <br />January ] 991 data indicated 0.31 feet were subsequently gained but <br />again, new control point coordinates were generated. No mining <br />activity took place in the vicinity of station 14 during 1996. The June <br />1996 measurements were witlSin the historic maximum and minimum <br />elevation values for this station. <br />Station 15: Station 15 was established for the 1991 surveying year. Station 15 <br />overlies approximately 700 feet of overbtirdcn and is located within the <br />600 - 800 foot overburden depth Stevens Gulch alluvium protective <br />Page -4- <br />