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<br />ENERGY FUELS COAL, INC. <br />SOUTHFIELD MINE <br />SEMI-ANNUAL SU85IDENCE MONITORING REPORT <br />(NOVEMBER, 1987 THROUGH APRIL, 1988) <br />Introduction <br />This report presents a summary of Southfield's quarterly subsi- <br />dence monitoring survey data for the period of record November, <br />1987 through April, 1988. Enclosed with this report is tabulated <br />survey monument and structure location orientation data. In <br />addition, survey data for the high resolution monument grid is <br />presented graphically, in cross-section form. Mining operations <br />remained active for the period of this report, although the ma- <br />jority of mining development was directed in areas away from the <br />monuments and structures. <br />South Subsidence Grid <br />Data collected from surveys of the high-resolution monument grid <br />(South Grid) are shown on Table 1, Subsidence Monitoring Data <br />Summary. Total displacement of each monument is presented in <br />cross-section form on Figure 1 and Figure 2, representing data <br />from the most recent survey. <br />The largest displacement occurs at Monument 15, a total of 2.11 <br />ft., as shown on Table 1. The monument is positioned near what <br />may be the center of the subsidence trough created by three ad- <br />jacent retreat mined panels. The displacement is much less than <br />the predicted worst case subsidence of approximately five feet. <br />Maximum expected subsidence predicted in he mining permit is 1.46 <br />feet, based on mining only the panel below the grid. Monument 4 <br />best represents subsidence related only to retreat mining the <br />first panel, a total displacement of 1.29 feet. This compares <br />favorably to the predicted value in the permit application. <br />The rate of subsidence of all grid monuments continues to be <br />minor (refer to Table 1) consistent with recent semi-annual re- <br />porting periods. It is anticipated that only minor subsidence <br />will continue to occur due to consolidation of the underground <br />cave area. <br />The apparent angle of draw, determined from cross-section Figure <br />1, is estimated between 29 and 29 degrees, consistent with the <br />previous semi-annual monitoring period. The angle of draw is <br />comparable to the predicted range of 29 to 25 degrees documented <br />in the mining permit. <br />City of Florence Water Line Monument <br />All data collected Erom the t4ater Line Monuments for the report- <br />ing period is presented on Table 2, Subsidence Monitoring Data <br />Summary. <br />