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<br /> <br />The data from all surveys indicate that sut~sidence behind <br />the longwall initially causes a cantilever effect on an <br />adjacent gobbed panel (incrementally lifting ground <br />elevations up). Then, as the longwall advances, the beam <br />bends or relaxes and ground elevations in the adjacent gobbed <br />panel decrease and reach equilibruim. <br />The cross-sections also show as much as one foot of surface <br />settlement in areas not predicted to subside. This is <br />expected since the monuments in these areas are located on <br />reclaimed spoil from strip mining. Surface settlement is <br />shown in the cross-sections as areas where the change in <br />ground elevation is uniform to a side of a subsidence basin. <br />The end points for the angle of draw were determined <br />incorporating the definition for surface settlement written <br />above. The angle of draw and end point locations are as <br />follows: <br />END ANGLE OF <br />ROW POINT DRAW (DECREES) COMMENT <br />K K-20 -1.19 UPDIP SIDE OF GOB <br />K K-4 19.25 DOSVNDI? SIDE OF GOB <br />NPR P-3 14.20 BEIiIND COB <br />S 5-12 9.16 DO{9NDI1? SIDE OF GOB <br />S 5-21 -1.16 UPDIP SIDE OF GOB <br />The angle of draw and the maximum subsidence shown above are <br />all within the predicted ranges submitted in Ecapires' permit. <br />The permit predicted the maximum subsidence to be 8-feet and <br />the maximum angle of draw to be 20 degrees. <br />The monitoring points will be surveyed again in March and <br />June of 1987. Results from these surveys will. be submitted <br />in ttie next semiannual report. <br />