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is not confident with the data from the early 1980's. Our <br />files do not have the original elevation data. I have <br />requested that he forward his files or information on this <br />subject. He has agreed. <br />The information provided is within the .1 foot accuracy limit <br />as specified in the Introduction. June through December 1992 <br />was the period of time where maximum subsidence occurred. <br />This is logical and according to prediction, as the long wall <br />operation undermined the old room and pillar workings above at <br />this time (see map of calendar of operations). Smax <br />experienced was on monument A9; 7.4 feet. It is interesting <br />to note that monument A8 was not surveyed, in fact no data has <br />been given on this monument since as far back as these reports <br />go- July 1991. This may have been the monument which <br />experienced maximum subsidence since on either side the <br />numbers gradually decrease. <br />Recommendation: <br />That the operator provide an explanation as to why monument A8 <br />has not been surveyed since 1991. <br />Secondly, that the original elevations of the entire A aeries <br />be sent as soon as possible. <br />IV. S Beries <br />The B series monuments are overlying room and pillar workings, <br />therefore the Smax predicted should be 10.5 feet. <br />Comments: <br />Original report 6-12/91 show accurate numbers in both the <br />original elevation and Smax total column. <br />However, the proceeding report 1-6/92 show that the numbers <br />for original pre-mining elevation do not match those in the 6- <br />12/91 report. The range of error is three to five feet (see <br />penciled in numbers on 1-6/92 report; column "pre-mining <br />elevation") and are significant on monuments B1,B2,B3,B4,B5 <br />and B6. Coincidentally, these are also the monuments that <br />show the greatest Smax, 7.4 to 10.95 feet, if the 6-12/91 <br />calculations are used. Monuments B3, B3, B4, B5 and B6 are <br />over the predicted Smax limit of 10.5 feet. <br />When these same monuments are calculated for Smax using the 1- <br />6/92 numbers, 7.3 is Smax, allowing for additional subsidence <br />of 3.2 feet to occur. Points B7, BS and B9 are the Smax for <br />the monitored period January through June of 1992. Monument <br />B12 is the Smax (0.4 feet) for the last reporting period, <br />July-December of 1992. <br />