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SUBSIDENCE SURVEY REPORT <br />January -June 1992 <br />Twentymile Coal Company, Foidel Creek Mine <br />This report summarizes the resuts of the subsidence monitoring program at the Foidel Creek Mine of <br />the Twentymile Coal Company. Surface subsidence has effectively ceased for all monitoring points. <br />1.0 SURVEY DATA <br />The attached table summarizes the results of the quarterly monitoring surveys. Because of a <br />misunderstanding with the surveyor, the A-series points were not surveyed during June 1992. The <br />omission of the June 1992 survey is not considered critical because previous surveys indicate that <br />subsidence has ceased along the A-series line. These points will be surveyed in September 1992. <br />2.0 MAP AND PROFILES <br />Map 1 is a plan view of the mining area showing the monument locations. The map illustrates mining <br />advance, by month, for this reporting period. Projected mining for the second half of 1992 is shown. <br />The map presents the surface topography and structures with in the subsidence area. <br />Profiles are attached for both the A-series and B-series monitoring lines. These profiles illustrate total, <br />measured subsidence. <br />3.0 STRUCTURES <br />Visual inspection of the monitoring points and the current, active, subsidence area were conducted in <br />June 1992. There is no visible surface evidence of subsidence or subsidence impacts. <br />4.0 CONCLUSIONS <br />Surface movement in the monitored area has ceased. No further subsidence is anticipated. However, <br />monitoring will continue until a technical revision has been prepared and approved. <br />There is no surface indication of subsidence or subsidence effects in the current mining area. No <br />negative impacts of subsidence have been noted. <br />