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some of the DH 50 series, DH -60 series and the 90 series had been installed above the <br />underground workings at the West Mine. Several of the 90 series sites, 94, 96, 97 and 98, <br />had been located on structures owned by the Grosse -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 <br />been installed above projectedfault tracesin an attemptto discern the effects ofdifferential <br />subsidence between alternating fault blocks. Stations No. 42 through No. 51 had been <br />located in areas of thick overburden. Stations No. 28 through 41, in contrast, had been <br />installed above overburden thicknesses considered typical throughout the permit area. The <br />high-resolution subsidence data had been used to evaluate and further define the projected <br />angle of draw. Data collected from these monument grids allowed verification in some <br />cases, and supported redesign in other cases, of the subsidence control plans prop osed by <br />the operator for implementation in the future. <br />The subsidence monitoring program for buildings and structures continues with the <br />monitoring of the Pitkin Mesa pipeline. Monuments PL -1 through PL -7 continue to be <br />measured twice a 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 <br />pillaring plan at that time was subsequently revoked by the Mine Safety and Health <br />Administration (MSHA). A modified plan, allowing only the mining of bottom coal in <br />certain areas, was approved by 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 <br />the original mine, which have been sealed since 1986. Annually submitted subsidence data <br />has indicated that the area has stabilized. The Division approved the revision February 11, <br />1992. <br />With the approval ofT echnical Revision No. 45 in January of 2005, D ivision approval was <br />given to suspend subsidence monitoring of the wide -spaced subsidence monument stations <br />14, 15, 16, 6, 81, 82, 83, 95, 99, DH -55, DH -65, and DH -68. With the approval of TR -45, <br />the only required subsidence monitoring involves those stations associated with the Pitkin <br />Mesa pipeline, namely, stations PL -1 through PL -7. <br />The subsidence portion of the application is in compliance with the Regulations. <br />XVI. Concurrent Surface and Underground Mining - Rule 4.22 <br />This section is not applicable to the Bowie No. 1 Mine. <br />XVIL Operations on Alluvial Valley Floors - Rule 4.24 <br />The discussion of Alluvial Valley Floors (AVF) can be found in Section 2.06 of Volume <br />1; in the AVF Appendix A, Volume 4 and in the Geo -Hydro Phase 2 studies of the PAP. <br />39 <br />