REP33908 - Laserfiche WebLink

Home Browse Search

~I I I II I I~' II I~~~ ~I~ sss Energy Fuels Coal, Inc. RECEIVED Southfield Mine JUN 111999 SEMI-ANNUAL SUBSIDENCE MONITORING REPORT Period: July 1, 1998 -December 31, 1998 Division of 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 1, Semi-Annual Subsidence Monitoring Data. These data show location and orientation of monuments and structures for the reporting period. Additionally, original survey data for all 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. EFCI will survey the South Grid monument network after mining operations have ceased as approved in the permit. EFCI performed two quarterly subsidence surveys of the 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 Ranch 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. 1.1 Thompson Ranch Structures Survey data for the 4th quarter 1998 indicate subsidence of the structures ranging from 0.39 to 0.43 feet. These data probably contain some error since no mining has occurred below the ranch area that would cause subsidence. In addition, there are no physical indications of subsidence on or near the monitored structures. Future monitoring should confirm that no subsidence is occurring.