Laserfiche WebLink
In Section 6.1.1 of the CNI Report, a discussion of the slope failure in the precambrian schist on <br /> the south slope of the WHEX is given. It began in January 2013 and has continued to displace. <br /> Based on data gathered by the geotechnical department at CC&V the instability area is <br /> considered a self-buttressing or regressive type failure. The instability was caused by pitward <br /> dipping foliation structures in the schist that have been measured to dip to the north-northwest at <br /> 25 to 45 degrees. This dip of the foliation structures results in possible instability in mining <br /> through this schist on the south side of the excavations, in particular in the area of cross section <br /> WH-1. This instability will not affect the north edges of the excavations, where CR82 and any <br /> other structures north of the pits are located. As is seen from the CNI Map on the previous page, <br /> the schist is limited to certain areas and the dip of the foliations on the north side has not, and <br /> should not in the future, result in any failures. <br /> Section 1.4 of the CNI Report recommends that the following ongoing work be conducted to <br /> ensure that future mining occurs without problems and all perimeter structures remain stable. <br /> CC&V has continued to conduct this work as recommended. The CNI recommendations are <br /> listed below: <br /> 1.4 Future Work <br /> Slope design is an iterative process; optimum slope design requires continuous effort to <br /> collect, interpret, and analyze geologic and geotechnical data as they become available. <br /> Data for the Globe Hill and Schist Island portions of the North Cresson mining area was <br /> pulled from previous cell and major structure mapping campaigns in the WHEX mining area. <br /> These rock fabric and major structure data were assumed for the new NA mining areas, and <br /> can therefore only be considered as "inferred"data. As mining begins on benches in the NA U <br /> mining areas,follow-up cell mapping and bench face geologic mapping should be performed <br /> along new benches to confirm the assumed data. Mapping is required to: <br /> 1. Confirm fracture characteristics and design parameters recommended in this study <br /> 2. Determine the upside potential in the recommended slope design <br /> 3. Detect any potential instability problems in a timely way <br /> CNI recommends an ongoing program of data collection and re-evaluation. Appendix A: <br /> Slope Monitoring and Management discusses specific components required to optimize the mine <br /> plan while maintaining safe operating conditions in the mine. <br /> Mining area mapping should focus on: <br /> 1. Identifying multibench-length major structures, especially those that may adversely <br /> impact stability <br /> 2. Locating water seeps <br /> 3. Identifying continuous zones of low rock-mass strength <br /> 4. Recording evidence for possible slope movement such as tension cracks, toe heaves, <br /> or recent movement along structures <br /> The geological, structural, and geotechnical data should also be compiled routinely. A <br /> 7 <br />