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Subsidence Monitoring Program <br />BRL maintains a subsidence monitoring program for the Bowie No. 1 Mine. Originally, the <br />program consisted of four components; visual inspection, wide - spaced grid subsidence <br />monuments, closely spaced, high- resolution subsidence monuments and the monitoring of <br />specific buildings and structures. However, with the suspension of mining operations in <br />December of 1997, the subsidence monitoring program has been reduced in size and scope. <br />The visual inspection phase is still in effect and consists of a walkover of the ground surface <br />above mined areas on a semiannual frequency. The applicant also commits to daily inspection of <br />the Steven's Gulch road, in order to protect the public. <br />BRL received approval to suspend the wide - spaced grid subsidence monitoring program. <br />Monitoring stations No. 1 through No. 27 had comprised a wide - spaced monument grid on <br />approximately 1300 -foot centers east -west and 2600 -foot centers north - south. These monuments <br />provided general observations regarding the magnitude of vertical subsidence occurrences. <br />Although not required, monument stations 6, 14 and 15 continue to be monitored twice a year <br />and the results submitted to the Division in the Annual Report. Additional wide - spaced <br />monuments No. 70 through No. 87 had been installed above proposed mine workings adjoining <br />the old east portals. Monuments with the notations of some of the DH 50 series, DH -60 series <br />and the 90 series had been installed above the underground workings at the West Mine. Several <br />of the 90 series sites, 94, 96, 97 and 98, had been located on structures owned by the Grosse - <br />Rhode Ranch. <br />The high- resolution subsidence monitoring program has been suspended. A number of <br />high- resolution, closely spaced subsidence monuments had been installed in sites selected <br />throughout the existing permit area. Monitoring stations No. 201 through No. 224 had been <br />installed above projected fault traces in an attempt to discern the effects of differential <br />subsidence between alternating fault blocks. Stations No. 42 through No. 51 had been located in <br />areas of thick overburden. Stations No. 28 through 41, in contrast, had been installed above <br />overburden thicknesses considered typical throughout the permit area. The high- resolution <br />subsidence data had been used to evaluate and further define the projected angle of draw. Data <br />collected from these monument grids allowed verification in some cases, and supported redesign <br />in other cases, of the subsidence control plans proposed by the operator for implementation in the <br />future. <br />The subsidence monitoring program for buildings and structures continues with the monitoring <br />of the Pitkin Mesa pipeline. Monuments PL -1 through PL -7 continue to be measured twice a <br />year and the results submitted to the Division in the Annual Report. <br />On May 10, 1996, the West Mine experienced a large bounce in Panel 2 Right. The pillaring plan <br />at that time was subsequently revoked by the Mine Safety and Health Administration (MSHA). <br />A modified plan, allowing only the mining of bottom coal in certain areas, was approved by <br />MSHA. <br />BRL submitted Technical Revision No. 16 to the Division in October 1991. The revision <br />allowed BRL to temporarily discontinue subsidence monitoring over inactive portions of the <br />original mine, which have been sealed since 1986. Annually submitted subsidence data has <br />indicated that the area has stabilized. The Division approved the revision February 11, 1992. <br />Page 36 of 42 <br />