Laserfiche WebLink
II. 8 Series <br />Monitored in 6-12/91 and 1-6/92 reports, not in 7-12/92 <br />report. <br />The S series monuments overlie two long wall panel <br />excavations, therefore the predicted Smax should be 13.0 feet. <br />Comments: <br />Pre-mining elevation figures differ from 6-12/91 to the 1-6/92 <br />report. Reason is unclear why these figures differ as they <br />are baseline numbers and should be a constant. Difference in <br />numbers ranges from a minimum of 2 feet to a maximum of 5 <br />feet. This is significant in that it is the baseline figures <br />from which actual subsidence calculations are made. <br />In addition, Smax is over the predicted amount on monuments <br />S2. 53 and S5 and very near to the predicted amount on <br />monuments S1, S4 and S6 when the baseline original elevation <br />figures are used from 6-12/91's report. If the figures in the <br />next report, 7-12/92 are used, then Smax is within 3.5 to 3 <br />feet. Smax of 13.0 feet is predicted to occur when the third <br />panel is to be mined, throughout 1993. Additional subsidence <br />will then occur, making up the 3 foot difference. Therefore <br />use of the 1-6/92 report figures will allow for this to occur, <br />whereas the 6-12/91 figures would only have an allowance of .1 <br />or .2 on the 52, S3 and S5 monuments. <br />Please refer to the original reports for the calculations and <br />my notes in the pertinent columns. <br />A final note is that this series was not surveyed in two <br />quarters in 1992, 3/10/92 to 6/18/92 respectively. No reason <br />given for the absence of data. <br />Recommendation: <br />operator should submit correct pre-mining elevation figures or <br />offer an explanation why these change through time. If <br />necessary, operator should revise predicted Smax limit in this <br />aeries due to actual on-the-ground information from the 6- <br />12/91 original elevation data. <br />Secondly, the operator shoul$ offer information why series not <br />surveyed in 1992. <br />III. A Series <br />The "A" series monuments overly old room and pillar workings, <br />therefore the predicted Smax is 10.5 feet. <br />The A series were monitored in all three reports. <br />Comments: <br />The A series is missing the original elevation (pre-F seam <br />mining) data. Discussion with Colin Stewart uncovered that he <br />