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i <br />SUBSIDENCE MONITORING REPORT <br />January - June 1992 <br />Cyprus Empire Eagle Mine No. 6, E-Seam Workings <br />1.0 INTRODUCTION <br />This report summarizes the survey schedule for and results of the <br />subsidence monitoring of longwall mining panels in the E-seam at <br />the Cyprus Empire Corporation (CEC) Eagle Mine No. 6 for the period <br />from January 1992 through June 1992. <br />Monitoring point locations are shown on the map titled, "E-seam <br />Longwall Subsidence Monitors". This map sheet also shows mine <br />workings, surface topography and overburden thickness. <br />2.0 MONITORING SCHEDULE <br />Subsidence monitoring was performed in March and June 1992. Both <br />surveys included all of monitoring lines "A", "B", "C", and "D", as <br />well as parts of line "S". <br />3.0 MINING ADVANCE <br />Monthly longwall mining advance for this reporting period, as well <br />as total mining to date, are shown on the map. Average extraction <br />height during the reporting period was 10 ft. <br />Mining during this period was limited because of a miners strike <br />and market conditions. <br />4.0 SUBSIDENCE RESULTS <br />The results of the surveys are presented on the attached tables for <br />each of the monitoring lines. The accuracy specification on the <br />monitoring survey is 0.1 ft. Therefore subsidence values of 0.1 ft <br />or less are not considered significant. <br />No subsidence was noted for perpendicular monitoring line "A". A <br />correlation of face position and survey dates indicates that the <br />"A" line was subjected to a nearly vertical angle of draw. <br />The "B", "C", and "D" lines were fully impacted by mining. The <br />differences in the magnitude of total subsidence between the "B" <br />and "D" lines and the "C" reflects the position of the "C" line <br />nearer the panel ribside. <br />