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iii iiiiiiiiniii r~i SUBSIDENCE MONITORING REPORT July -December 1992 Cyprus Empire Eagle Mine No. 6, E-Seam Workings 1.0 INTRODUCTION This report summarizes the survey schedule for and results of the subsidence monitoring of longwall mining panels in the E-seam at the Cyprus Empire Corporation (CEC) Eagle Mine No. 6 for the period from July 1992 through December 1992. Monitoring point locations are shown on the map titled, "E-seam Longwall Subsidence Monitors". This map sheet also shows mine workings, surface topography and overburden thickness. 2.0 MONITORING SCHEDULE Subsidence monitoring was performed in September 1992. This survey included all of monitoring lines "A", "B", "C", and "D". Weather conditions and snow prevented monitoring in December. 3.0 MINING ADVANCE Monthly longwall mining advance for this reporting period, as well as total mining to date, are shown on the map. Average extraction height during the reporting period was 10 ft. Mining of longwall panel 2 East was completed in December. Mining of the 3 East longwall panel is projected to start in March 1993. Mining during this period was limited because of market conditions. 4.0 SUBSIDENCE RESULTS The results of the monitoring surveys are presented on the attached tables for each of the monitoring lines. The accuracy specification on the monitoring survey is 0.1 ft. Therefore subsidence values of 0.1 ft or less are not considered significant. Control point Amos is used to survey the "A", "B", "C", and "D" monument lines. During this reporting period, a control survey resulted in the assignment of a new elevation to this control point that is 0.15-ft lower than the previous elevation. The results reported in the tables have been corrected to reflect this change by subtracting 0.15-ft from each baseline elevation. Grpru~ Ertp~n peoniEa~ 71, 1 WI s~era.~ a.pon wue ~