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Monitoring station data sheets are appended to this report for reference along <br />• with a summarized tabulation of monument and control station elevation changes. <br />Stations 28-36: Stations 28-36 cerise a hick resolution transect of survey <br />points paralleling the 1st North, 8 East, 8 North, 11 North <br />panel. The stations were established to portray subsidence <br />effects inclusive of draw angle under conditions typical of <br />most of the permit area (i.e. moderate werburtien and gentle <br />topography). The 11 North panel underlies approximately 600 <br />feet of over2a~xden and was retreat mined in March 1986. 'ibtal <br />change in elevation for these sites averages -0.99 feet arcl <br />ranges from -0.79 feet to -1.14 feet. Elevation chatxJes over <br />the last several years have been m;nimat with the exception of <br />those measured during October 1989. New control station <br />ooorrlinates were established at that time arc3 elevation <br />adjustments of approximately -0.45 feet were typically <br />mPa~fired. <br />Stations 37-41: Stations 37-41 ca~rise a hick resolution trdnsect of survey <br />points running perpendicular to the 1st North, 8 East, 8 <br />North, 11 North panel. 'These stations were also established <br />to portray subsidence effects inclusive of draw angle under <br />conditions typical of most of the permit area (i. e. moderate <br />overbur>;ien arri gentle topography). 'The 11 North panel <br />underlies approximately 600 feet of overburden and wa=s retreat <br />mined in March 1986. Total change in elevation for these <br />• sites averages -1.40 feet and ranges from -0.62 to -2.34 feet. <br />'Ihe most significant movements detected at these sites were <br />measured in August 1986. Again, recent elevation changes <br />have been minimal with the exception of those measured during <br />October 1989. New control station coordinates were <br />established at that time and elevation adjustments of <br />approximately -0.45 feet were typically measured. <br />Stations 42-51: Stations 42-51 coaprise a hick resolution trarLSec:t of survey <br />points paralleling the 1st North, 8 East, 5 North, 4 West <br />panel. Stations 42-51 are intended to portray subsidence <br />effects inclusive of draw angle in deep overburden conditions. <br />The 4 West panel underlies approximately 1600 feet of <br />overburden and has not been undermined to date. It is <br />reasonable to assume that no subsidence related elevation <br />adjustments have occurred on this transec~t. Howev~s, data <br />indicates that elevation changes for these sites have averaged <br />-0.98 feet. 'Ihe majority of this motion was detected during <br />the 1989 survey and is thought to be related to the <br />establishment of new control station coordinates. Surveyed <br />sites were generally found to be approximately 0.90 feet lower <br />as a result of the 1989 survey. Lesser movements detected <br />prior 1989 are thought to be characteristic of normal changes <br />associated with the geology in this area (see Station 27). <br />Stations 52-69: Stations 52-69 co~rise a high resolution tran_sect of survey <br />• points perpendicular to the 1st North, 8 East, 8 North, 12 <br />North panel. This panel underlies approximately 550 feet of <br />overbunden in the vicinity of the transec-t. 'The panel was <br />7 <br />