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ENERGY FUELS COAL, INC. SOUTHFIELD MINE SEMI-ANNUAL SUBSIDENCE MONITORING REPORT (November, 1986 through April, 1987) Introduction This report presents a summary of quarterly subsidence monitoring data collected at the Southfield Mine for the period November, 1986 through April, 1987. The data are presented in summary tables, and in cross-section form for the South Grid monitoring stations. South Subsidence Grid All data collected at the South Subsidence Grid Eor the above referenced monitoring period are presented on Table 1, Subsidence Monitoring Data Summary. In addition, total subsidence data are portrayed in cross-section form on Figures 1 and 2. An examina- tion of the data on Table 1 indicates that minor subsidence is occurring at all but two of the 23 stations consistent with pre- vious semi-annual reporting periods. The maximum total subsi- dence; 1.94 feet, occurs at monument No. 15. The magnitude of the subsidence is much Iess than the predicted 5.0 feet mentioned in the previous semi-annual report related to the combined effect of extracting three mining panels. For the period of record of this report, the rate of subsidence is greatest along the East and North arms of the monument grid, ranging from 0.01 to 0.03 'feet. This cate has decreased as com- pared to previous semi-annual reporting periods. The predicted future rate of subsidence of the South Grid monuments is expected to continue to decrease as no further mining operations will impact the monitoring sites. City of Florence Water Line Monument All data collected at the Water Line Monuments for the period of record are portrayed on Table 7_, Subsidence Monitoring Data Sum- mary. No mining activity has occurred in the vicinity of the subsidence monuments for the period of record. The data indicates that subsidence is occurring only Monument "E" consistent with the previous semi-annual monitoring period. The total subsidence to date at this monument is 0.99 feet which is considerably less than the expected worse case value of 2.79 feet documented in the permit application. It is anticipated that only minor additional subsidence will occur at the Water Line Monuments until retreat mining operations are commenced.