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Semi-Annual Subsidence MonitorinP R~p~ <br />Period: July 1, 1996 -December 31, 1996 <br />Page 2 <br />As mentioned above, EFCI reestablished the monument during the forth quarter to a location <br />approximately 54 feet from the original station (and left the original monument intact). The <br />original monument has been overgrown by an old ponderosa pine that greatly inhibits visibility of <br />the monument during surveying. The close proximity of the new monument will provide <br />comparable data during future surveys. <br />1.3 Florence Water Line <br />Survey data obtained at the eight monuments along the Florence Water Line indicate minor <br />subsidence occurring only at Monuments B, C, D and E during the reporting period. The amount <br />of measured subsidence at these monuments ranged from 0.11 to 0.72 feet. Survey data from <br />Monuments F, G, H and I show similarly small changes except in a positive direction. These <br />data may reflect some error in GPS measurements as previously discussed. The next quarterly <br />surveys will verify the accuracy of the GPS equipment data. <br />The maximum measured subsidence along the water line has occurred at Monument I, totalling <br />3.05 feet since the original survey. This value is within the permit maximum expected and worst- <br />case expected subsidence values of 2.79 and 4.36 feet respectively. <br />No new surface cracks or other subsidence related features were observed during the reporting <br />period. Surface cracks that appeared on County Road 15 during May 1996 have healed by natural <br />processes. <br />Subsidence monitoring of structures 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 />