2008-05-01_REPORT - C1996083 (8)

Home Browse Search

Introduction •~ This report is for the period from July 2007 through December 2007. Mine Construction of the Bowie No. 2 Mine began during May of 1997, with coal production beginning during August 1997. The mining permit application for the Bowie No. 2 Mine requires the operator to submit the results of the subsidence monitoring programs and the results of the visual inspections of known modern and historic landslides within the permit and adjacent area for stability in June and December of each year and report these results to the Division within 30 days of the ends of the reporting periods. The operator is also required to inspect these landslides, both modern and historic monthly for six months immediately after retreat mining occurs. This same inspection routine is applied to any spring or pond in the immediate proximity of retreat mining. Longwall mining during the period included finishing the B-4 panel, complete mining of the B-5 panel and beginning mining in B-6 panel. Visual Inspection of known historic and modern landslides. A visual inspection of all known historic and modern landslides was conducted during October 31, 2007 by Brad Lindsay, Rock Logic Consulting LLC. Mr. Lindsay's report is attached. Numerous new subsidence cracks were noted. • Increased Inspection activity associated with retreat mining. Accessible subsidence cracks are repaired during coal exploration events and are monitored by both coal exploration supervisors and hydrologic monitoring technicians. The accessible visual results of the subsidence effects associated with the Bowie No. 2 Mine are overlain on Map 27-C Subsidence Features. Map 27-C is enclosed. During this period, Spring 17 and Spring 3 were impacted or re-impacted by mining activities. Potentially impacted or re-impacted means the mine workings or angle of draw of the mine workings passed under the monitoring point during the reporting period. No influence to any hydrologic monitoring points was observed during this period. Results of Subsidence Survey Monitoring The results of the August and October 2007 monitoring are attached. As in the past, the survey was performed by Cragg Surveying using GPS methods. Analysis of Subsidence Data The following table presents an analysis of the subsidence survey data. Panels B-4 and B-5 were complete and mining in panel B-6 was about 50% complete at the time of the survey. Following is a summary of the survey data collected during the period. There was no activity near Hubbard Creek or Dove Gulch. The survey data presents another survey of the subsidence over the west D-Seam longwall panels after all three panels were complete and the subsidence attributable to panels B-1, B2 and B3. There were only a few subsidence monuments over the B-4 and B-5 panels. -2-