_INSPECTION - C1996083 (29) - Laserfiche WebLink

Home Browse Search

Bowie No. 2 Mine Field Evaluation Colorado Division Reclamation, Mining and Safety(CDRMS) Permit No. C-96-083 Wednesday, July 29, 2009 9:00 a.m. —4:30 p.m. Participants: Elizabeth Shaeffer, USDUOffice of Surface Mining(OSM) Howard Strand, OSM Joe Dudash, Colorado Division of Reclamation, Mining, and Safety(CDRMS) Bill Bear, Bowie Resources Jim Stover, J.E. Stover and Associates, Consultant Weather conditions: sunny and warm in the morning, showers in the afternoon The purpose of this evaluation was to gather information on subsidence related material damage to, and of the diminution of reasonably foreseeable use of, structures and renewable resource lands within permit and adjacent areas at the Bowie No. 2 mine. As part of our oversight process,the Colorado Team is evaluating"Prevention of Material Subsidence Damage to, and the Diminution of Reasonably Foreseeable Use of, Structures and Renewable Resource Lands." This site visit helped the Team assess subsidence-related impacts and mitigation measures for the purpose of our study, and verified whether mine operators are complying with applicable regulatory and permit requirements pertaining to the monitoring and reporting of the effects of underground mine subsidence. Bill Bear and Jim Stover provided a summary briefing of the situation at the main office. They provided maps of panels B6, B7, and B8 of the mine that identified areas where subsidence had occurred during the past 2 years, as well as the degree of subsidence. Mining Seam Panels B6 and B7 were evaluated in the field for this topic. Although not part of the topic evaluation, we observed Bruce Park Dam and the Terror Creek Reservoir. The company has installed eight(8) inclinometers to measure slide activity, as well as a solar-powered notification system if such movement does occur. Five equally-spaced subsidence monuments have been installed across the dam and no settlement has occurred to date (see Figures la and lb). Freeman Gulch, which lies above Panel B6 and was undermined approximately 18 months ago, was identified and categorized as a potential renewable resource land by virtue of surface water runoff that infiltrates the gulch and finds its way to an aquifer on the disturbed area. Freeman Gulch has two surface water monitoring sites. The upper Freeman Gulch monitoring site and the lower Freeman Gulch monitoring site are used to see if any surface water is percolating into the ground due to subsidence. Subsidence monuments consist of 4-foot capped rebar that is surveyed to determine movement. The mine provided a map with the locations of monuments 8A through 8D for Freeman Gulch. These monuments showed, and the team verified, that approximately 10 feet of subsidence has occurred as a result of mining activity(see Figure 2). This subsidence was predicted by the mine in accordance with their approved subsidence monitoring program. We also observed the "Freeman Gulch Slide Area"that is located at the "tailgate"of the B6 Seam.