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<br />Energy Fuels Coal, Inc. <br />Southfield Mine <br />Semi-Annual Subsidence Monitorino Report <br />Reporting Period: May 1, 1993 - October 31, 1993 <br />Introduction <br />This report presents a summary of all subsidence survey data <br />and discussion of these data for the semi-annual reporting period <br />referenced above. The following discussion of subsidence data <br />includes comparisons of measured subsidence with the values <br />predicted in the permit application. Subsidence data is presented <br />on three summary tables attached to this report. Additionally, data <br />from the high resolution survey grid is presented graphically on <br />two cross-section diagrams. <br />Discussion <br />1) High-Resolution Grid <br />Energy Fuels monitors the 23 monuments of the high-resolution <br />grid on a semi-annual basis. Results of the monitoring provides <br />information on the magnitude of subsidence and the estimated draw <br />angle as a result of mining at Southfield. Summarized survey <br />monitoring data for the reporting period are presented on Tabled , <br />South Subsidence Grid. In addition, these data are presented; in <br />cross-section format on Figure 1 and Figure 2. <br />A review of, the subsidence data for .the reporting period <br />indicates that only minor additional subsidence is occurring in the <br />area of the monitoring grid. Consistent with previous monitoring <br />periods, surveys of the grid monuments show ground movement of 0 to <br />0.04 feet. This magnitude of vertical change approaches the limit <br />of detection by standard level survey methods. <br />The maximum subsidence measured in the monument grid occurs at <br />Monument 15. Cumulative vertical change at this point was 2.33 feet <br />through the period of this report. This value is approximately, 43 <br />percent of the maximum 5.40 feet as predicted in the permit <br />application. <br />The estimated draw angle is shown on Figure 1 based on a plot <br />of the subsidence profile of grid monuments through the reporting <br />period. The resulting draw angle of 25 to 26 degrees is consistent <br />with previous reporting periods and compares reasonably with the 20 <br />to 25 degree draw angle predicted in the permit application. ~ <br />Monitoring data presented in this report are consistent with <br />previous reports and within predicted values according , to <br />Southfield's permit application. Only minor additional subsidence <br />is expected to occur at the monuments of the South Subsidence Grid. <br />