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SEP 28 '93 01~27PM CYPRUS HRNNR • • P.4 complete by the June 1993 monitoring survey. Further monitoring and analyses may result in changes to values presented in this interim report. 4.1 Monument and Surfaee Movement The results of the monitoring survey is presented on the attached table and profiles for the monitoring lines. Analysis of the survey data Indicates that the accuracy of the monitoring survey is about 0.1 ft. Therefore subsidence values of 0,1 ft or less are not considered significant, Visual inspection of the monitoring lines in March 1933 and June 1993 showed no observable effects of subsidence at the ground surface. 4.1.1 1000-Line The 1000-line was not undermined during this report period. 4.1.2 3000-Llne The 3000-line is located along the centerline of the 2 Left longwall panel. The line extends out from the longwall start-up room, Data from the 3000-line indlcetes that an adjustment of -0.1 ft should be applied to the baseline elevations for the monitoring points. This adjusted baseline is illustrated on the profile labelled Subsidence Line 3000. These adjustments are not reflected on the current tabular summary of the data. The corrections will be applied to the next report. The angle of draw calculated for the 3000-line is approximately 18 deg for the 1050-ft overburden depth. This is slightly greater than the projected 15 deg start profile draw angle. Maximum subsidence, corrected for the -0.1-ft baseline correction is 3.5 ft, or 42 in. This is slightly less than the projected 44 inches of subsidence. The 8.7-ft mining height results in a ratio of 0.41 for maximum subsidence to mining height. 4.1.3 4000•Line The 4000-line is located perpendicular to the centerline of the 2 Left longwall panel. The downdip side of the monitoring line did not extend outside of the active subsidence area. The data indicate that the downdip angle of draw for the 4000-line is greater than Ly1,u~TwnMnIN f~peMneer7l, 1110 41nia nn W l 6vCrOna R1poR paps 1