2014-02-05_REPORT - C1981014 - Laserfiche WebLink

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Energy Fuels Coal, Inc. Southfield Mine 2013 SUBSIDENCE MONITORING REPORT October 2013 Subsidence Survey Introduction This report includes discussion and analysis of field survey data obtained on October 21, 2013, at the Southfield Mine for Energy Fuels Coal, Inc. (EFCI). The survey was conducted in accordance with permit requirements in Technical Revision No. 36 (TR -36), as approved on November 20, 2003. This revision approved a reduction in the frequency of subsidence surveys, elimination of three monuments, and specified that two additional subsidence surveys would be conducted during year 3 (2006) and year 9 (2013) of the Ten Year Reclamation Liability Period. In addition, the revision required a subsidence survey at the South Subsidence Monitoring Grid during year 9 (2013). Subsidence Survey Subsidence surveying was completed as required in October 2013, for all the structure locations and for the monuments at the south subsidence grid. Summarized data collected for the surveys are shown on attached Exhibit A, General Mine Area Monuments, and Exhibit B, South Subsidence Monitoring Grid Monuments (a.k.a. High Resolution Grid). The data shown include the original surveyed horizontal and vertical location of each monument, date of the original survey, the surveyed location of each monument for the period of this report, and the calculated change of the coordinates. Location of the structures and monuments with respect to the extent of the Southfield Mine are shown on Map 17, Mine Plan Map, in the approved permit application. Subsidence surveying was primarily conducted utilizing differential GPS equipment for both horizontal and vertical control. Surveying at the Thompson Ranch Structures involved use of both differential GPS equipment and a total station instrument. Discussion of the current subsidence survey data, any relevant visual observation information, and mitigation activities for the period of this report is provided below. Discussion 1.0 Structures Structures monitored 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 Exhibit A, General Mine Area Monuments. Discussion of survey monitoring data compared to permit predictions for inventoried structures follows below. 1.1 Thompson Ranch Structures Survey data for the reporting period indicate vertical changes, compared to original data, ranging from 0.000 to 0.010 feet at the north house and barn locations respectively. No subsidence is expected in the area of the structures since only advance mining utilizing large support pillars occurred below the ranch area. In addition, there are no physical indications of subsidence observed on or near the monitored structures.