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<br />Semi-Annual Subsidence Monitoring Rgpg~ <br />Period: Period: January 1, 1999 -June 30, 1999 <br />Page 2 <br />1.2 Newlin Creek Point <br />Survey data for the Newlin Creek point show a change of +0.41 feet of subsidence through the <br />2nd quarter of 1999. Similaz to the survey data for the ranch swctures, above, it is not likely <br />that any subsidence has occurred at this monument. No mining operations have occurred in the <br />vicinity of this survey point since 1982 to cause additional subsidence. <br />1.3 Florence Water Line <br />Survey data obtained at the eight monuments along the Florence Water Line indicate minor <br />subsidence occurring in the azea of the water line during the reporting period. The amount of <br />measured subsidence at these monuments ranged from 0.06 to 1.66 feet. No recent mining has <br />been done in the vicinity of monitoring locations that would cause additional subsidence. <br />The maximum measured subsidence along the water line occurs at Monument I, with a current <br />deflection of 3.42 feet as compared to the original survey. This value is within the permit <br />maximum expected and worst-case expected subsidence values of 2.79 and 4.36 feet respectively. <br />1.4 Visual Observations <br />New surface cracks appeared on the surface of the Newlin Creek light-use road, 50 to 500 feet <br />south of the topsoil pile area, during February. The cracks were no more than approximately <br />one-half inch wide, aed caused no damage to the gravel road. Appearance of these cracks follows <br />retreat mining of the 1 South submain section during the 4th quarter of 1998. No other cracks or <br />other subsidence related features were observed during the reporting period. Previously observed <br />surface cracks, primarily on County Road 15, have healed and not reappeared. <br />1.5 Conclusions <br />Subsidence monitoring of swctures indicates that subsidence is occurring only at certain locations <br />along the water line, and that the magnitude of displacement is within predicted values. Only <br />minor additional subsidence is expected to occur at the structure monitoring locations. <br />