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The December 87 surveys show that subsidence over the first <br />and second panels has reached maximum. This is depicted <br />on graphs located on pages 4 through 15. These graphs show <br />the change in elevation over the last five surveys for <br />twelve particular monuments. These monuments were chosen <br />because they are located at the centers of panels one and <br />two, locations most receptive to subsidence. Note the <br />lines are all flat. This information along with the <br />pressure cell study conducted by the BLM indicates <br />subsidence has stopped and reached maximum. <br />Currently the longwall is in the fourth panel. The survey <br />shows that the change in elevation over the first two <br />panels was negligible and there is little change over the <br />third panel. The maximum subsidence for the affected rows <br />are shown in table 1. <br />Table 1 Maximum Subsidence 12/88 <br />Row K S NPR R T V O <br />Mont. K-8 S-8 R-9 R-22 Q-1 T-1 V-2 O-2 <br />Number <br />Maximum 6.89 6.54 5.23 7.05 2.37 5.63 4.49 5.22 <br />Subsid. <br />The definitions of surface settlement is defined as areas <br />where the change in ground elevation is uniform to a side <br />of a subsidence basin. Using this definition the end <br />points for the angle of draw were determined. The angle of <br />draw and end point locations are as follows: <br /> END ANGLE OF <br />ROW POINT DRAW (DEGREES) <br /> <br />K K-20 -1.19 <br />NPR P-4 14.67 <br />S S-3 19.10 <br />S 5-21 -1.16 <br />COMMENT <br />UPDIP SIDE OF GOB <br />BEHIND GOB <br />DOWNDIP SIDE OF GOB <br />From June 86 Survey <br />UPDIP SIDE OF GOB <br />-2- <br />