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,~ <br /> <br />Mr. Thomas Gillis <br />July 30, 1985 <br />Page two <br />~II ~I~~I~~I~~~~~~I~ <br />GMCC is certain that no subsidence has occurred. As can be seen from the relative <br />change in elevation it appears that some movement has taken place in the <br />subsidence monuments. This apparent movement is believed to be caused by <br />surveying inaccuracies. These inaccuracies could be attributed to different <br />equipment, a different instrument man and climatic differences. <br />Subsidence is generally a result of major caving or heaving. These conditions <br />can be monitored underground except in sealed areas. As long as the mine <br />is idle GMCC proposes to monitor subsidence quarterly by performing visual <br />mine inspections to detect any major caving. If no major caving is noted <br />no further subsidence monitoring shall be performed. If a major cave area <br />is noted GMCC shall perform field surveys to further check for subsidence. <br />Results of the visual mine inspections and any field survey work shall be <br />submitted to the Division annually. <br />If there are any further questions about these results or about the proposed <br />subsidence monitoring plan please let me know. <br />Sincerely, <br />;%. <br />~ j Larry M. Reschke, P.E. <br />'-~" Mine Engineer <br />LMR:JES:tgn <br />cc: Henry Barbe <br />Jim Stover <br />