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1988 SEMI ANNUAL SUBSIDENCE SURVEY REPORT <br />• I. SURVEY DATA <br />The coordinate locations and surveying data of subsidence monuments <br />which are currently being monitored are tabulated in Appendix A. Due <br />to the inaccessibility of monitoring sites during the first quarter, <br />surveying was not completed by the end of March 1988. Twentymile <br />Coal Company was able to conduct monitoring of all sites by 28 April <br />1988. <br />II. MAPS <br />A. Plan View <br />The enclosed map (Foidel Creek Mine - Current Status Map ) shows a <br />plan view of the existing underground workings (updated to 1 July <br />1988), future mining projections, surface topography and structures, <br />and subsidence monument locations. <br />B. Cross Section <br />The recent survey of the Foidel Creek monuments has not indicated <br />subsidence to be occurring above the mains. l'he subsidence which did <br />occur above the 1st Panel South appears to have stabilized. Because <br />no appreciable recent change has been indicated for either of these <br />• areas, the associated cross sections are not included with this semi <br />annual report. Both cross sections are included with the 1987 Annual <br />Subsidence Survey Report. <br />III. HYDROLOGY <br />Tlie underground mine is dewatering the adjacent Wadge overburden <br />aquifer. Water monitoring data will continue to be included in the <br />annual hydrology report. <br />IV. STRUC'~URES <br />The structures currently being monitored which are included with this <br />semi annual report include the CYCC Training Building, Northeast <br />Water Tank, Southwest Water Tank, and South Water Tank. With the <br />exception of the Training Building, these structures are adjacent to <br />the 1st Panel South. Partial extraction of pillars occurred at <br />different time periods during 1987 with full pillar extraction being <br />conducted in June and July of 1987. South, the tank and connecting <br />water line fractured and were subsequently repfased. The damage may <br />have resulted from the subsidence associated with the 1st Panel South. <br />u <br />r' <br />~~t ` <br />