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Energy Fuels Coal, Inc. Southfield Mine SEMI-ANNUAL SUBSIDENCE MONITORING REPORT (Period: November 1, 1994 -April 30, 1995) Introduction The semi-annual subsidence monitoring report includes a summary comparison of survey monitoring results and tfie predictions for inventoried structures. Additionally, tabulated survey data is attached showing location and orientation of monuments and structures. Cross-sections are attached that graphically represent survey elevation data at the high-resolution monument grid. Discussion 1. South Subsidence (High-Resolution) Grid The South Subsidence Grid was surveyed on asemi-annual basis to determine orientation changes of the 23 monuments. Location of the monument grid and the mine layout are shown on Map 17 in the permit application. Summarized survey data for the period of this report are shown on Table 1, Semi-Annual Subsidence Monitoring Data Summary. These data are also shown graphically, in cross-section form, on Figures 1 and 2. From the vertical displacement data plotted on Figure 1, the estimated draw angle is depicted. Comparison of the monitoring data and subsidence predictions show that the maximum surveyed subsidence, 2.30 feet at Monument 15, exceeds the permit prediction of 1.46 feet. Tn addition, the subsidence at adjacent Monuments 13 and 14 also exceeds the maximum expected value. The higher than expected subsidence values are a result of mining a second, wide panel adjacent to the monitored panel and under the above mentioned monuments (shown on Map 17). The increased subsidence due to mining wider panels is explained in the Rocky Mountain Geotechnical report located in Exhibit 23 of the permit application. The survey data show that little or no movement of the monuments occurred during the reporting period. This condition is consistent with preceding monitoring periods. It is likely that the caved area and the overlying strata has wnsolidated and is becoming stabilized The estimated angle of draw, shown on Figure 1, is 28.5 degrees. This compares favorably with the 29 degree maximum angle predicted in the permit application. EFCI conducted visual inspections for surface cracking while performing the field surveys. These inspections concentrate on the areas of the surveyed monuments. Surface cracking occurs between Monuments 11 and 12 on the north-leg of the high-resolution grid. This consists of one crack, approximately 40 feet long and a maximum of 1 inch wide. This crack is approximately 4 years old, and is slowly healing during precipitation events since it occurs in the thick surface colluvium materials.