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2.05.6(6) <br />The Operator will establish a minimum of two subsidence monitoring <br />gridlines across the stream channel in areas of anticipated vertical <br />displacement that will be surveyed prior to and following longwall mining <br />beneath the area. These survey data will be used to confirm/refine the <br />subsidence predictions for the area. (BLM Decision Record (DOI-BLM-CO- <br />S050-2013-0010 EA)) <br />The results of the subsidence monitoring programs and the results of the <br />visual inspections for mass movement features will be submitted semi- <br />annually for the reporting periods ending in June and December, within 30 <br />days of the end of the reporting periods. <br />The subsidence monitoring program will extend at least two years beyond <br />cessation of mining in any area, consistent with the need for verification of <br />the subsidence prediction. The DRMS must approve the cessation of <br />subsidence monitoring through a technical revision. <br />Mining has ceased in all areas of the mine effective February 26, 2016, over <br />two years ago. The Operator has demonstrated the PL series subsidence <br />monuments have been stable during the last two years and the 37 series <br />monuments have been stable since they were installed. Subsidence <br />monitoring performed to date has verified the subsidence prediction. <br />Subsidence monitoring has ceased at the mine effective April 2018. No <br />2018 subsidence reports are required. <br />(f)(vi) Map 14 & 14B, Mine Plans, present the location of the underground <br />workings. Map 27, Subsidence shows the subsidence survey monument <br />locations and the limited extraction zones for Pond P-1, Hubbard Creek, <br />Terror Creek, Stevens Gulch and near the outcrop. The limited extraction <br />zone near the outcrop is shown as the 110' overburden line. Mining in low <br />overburden areas adjacent to the possible fault trace is explained in section <br />(f)(ii)(B)• <br />(vii) Map 14 & 1413, Mine Plans, present the location of the underground workings <br />including the size, configuration, and approximate location of pillars and <br />entries and extraction ratios. Measures taken to prevent or minimize <br />subsidence are presented on Maps 14, 14B and Map 27, Subsidence. <br />TR -116 2.05-172- 04/18 <br />