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III IIIIIIIIIIIII III ,, Energy Fuels Coal, Inc. " Southfield Mine RECEIVEQ SEMI-ANNUAL SUBSIDENCE MONITORING REPORT Period: July 1, 1997 -December 31, 1997 MAR pq eggs Division o(Minerals 8 Geology Introduction The semi-annual subsidence monitoring report compares field survey monitoring data to permit predictions for inventoried structures. Summarized survey data are shown in attached Table I, Semi-Annual Subsidence Monitoring Data. These data show location and orientation of monuments and structures for tine reporting period. Additionally, original survey data for alt subsidence monitoring locations are shown on attached Table 2, Original Subsidence Monument Data. Field surveys are conducted on only the structures (including the Newlin Creek point) shown on Table 2. By approved revision to the permit, EFCI will not survey the South Grid monument network until after mining operations have ceased. EFCI performed two quarterly surveys of the subsidence monuments and structures shown on Table 1 during the reporting period. The surveys were done using conventional EDM equipment for both horizontal and vertical control. Discussion of the subsidence data, and any current visual observation information, is shown below. Discussion 1. Structures Structures monitored quarterly for subsidence include the Thompson Kanch buildings, the Florence City water line, and the Newlin Creek point. Summarized survey data for these structures are shown on accompanying Table 1, Semi-Annual Subsidence Monitoring Data Summary. Location of the structures and monuments with respect to the Mine layout are shown on Map 17 in the permit application. Discussion of survey monitoring data compared to permit predictions for inventoried structures follows below. I.1 Thompson Ranch Structures Survey data for the final quarter (4th quarter 1997) of the reporting period indicate that subsidence in the range of 0.70 to 0.78 feet has occurred. These data indicate more vertical movement as compared to previous reporting periods. EFCI believes that the data are exaggerated due to inherent errors in the survey method, and actually indicate that no subsidence is occumng in the area of the ranch structures. No mining has occurred below the ranch area that would cause subsidence.