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composite geology and structure map should be updated at least once a year. Periodic <br /> BFAsurveys should be conducted along benches to evaluate the success in achieving the bench <br /> geometries and interramp angle recommendations. <br /> 1.4.1 Surface/Underground Mine Interaction <br /> At the time of this report underground mine designs had not yet been completed for the <br /> NA U study area. Once the initial underground designs are ready, but before construction begins, <br /> a geotechnical evaluation should be performed to investigate the possibility of interaction <br /> between the surface and underground operations. <br /> 1.4.2 Pre-split Blasting on Final Wall <br /> CNI recommends that CC&V continue implementing pre-split blasting, especially on the <br /> final walls. Pre-split holes drilled to the full double bench height of 70 feet will improve the <br /> reliability of the benches by increasing the bench face angle. More information about pre-split <br /> and other controlled blasting methods is presented in Appendix B: Controlled Blasting. <br /> In addition to constructing clean, well-cut bench faces, the reliability of catch benches <br /> can be improved by ensuring the toes of each mining increment are cleaned before proceeding <br /> with the next increment. CC&V is generally very good with this practice. Leaving material that <br /> can be easily cleaned is not good practice because it reduces the capacity of the bench to catch <br /> falling rock and also interferes with the drill's ability to reach the toe of the current bench. <br /> 1.4.3 Slope Monitoring <br /> Any major slope failure along mining area walls could disrupt mining activity; therefore, <br /> a slope monitoring program is recommended at Cripple Creek. The program should include the <br /> following: <br /> 1. Periodic reconnaissance mapping should be conducted to identify areas of <br /> potential instability. <br /> 2. Prisms should be placed throughout the mine and wireline extensometers be <br /> installed at areas of potential instability. <br /> 3. Benches (particularly those above critical access haul roads or mine <br /> installations) should be periodically inspected where slope instability would <br /> have the greatest operational and financial impact. <br /> Using pertinent data collected from routine mining area mapping and ongoing <br /> geotechnical programs, monthly reports with accompanying maps should be published and <br /> circulated to key mining personnel. Contingency plans that allow for alternative mining schemes <br /> should be developed in case of slope instability at critical locations. <br /> 1.4.4 Hydrology <br /> CNI recommends conducting the following groundwater-related work at Cripple Creek: <br /> L Water seeps along mining area walls should be documented and seasonal <br /> fluctuations, if any, should be recorded. This information can be collected <br /> during routine mining area mapping. <br /> 2. Records should be kept on blasthole water depths if encountered. <br /> 3. Piezometers should be installed at strategic locations along the final wall to <br /> define the possible influence perched groundwater and its fluctuations may <br /> have on slope stability. <br /> 8 <br />