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8 <br />1. Establish a monitoring program to determine what areas of the pit slope are <br />moving, at what rate, and with sufficient precision to determine if movement is <br />accelerating or decelerating. Relative movement monuments will be set at scarps <br />and cracks. Prisms for periodic EDM theodolite readings will be placed on the pit <br />slope, including the slide mass. The relative movement monuments and survey <br />prisms can be placed initially in parts of the pit where access is safe and then <br />placed in additional areas as sufficient data is gathered to determine the areas that <br />are safe for entry. Yenter typically uses the U.S. Army Corps of Engineers Manual <br />EM1110-2-1009 - Structural Deformation Surveying for guidance on the survey <br />methods and type of data analysis. <br />2. Survey the scarp locations and geometry of the slide. Using this data, estimate the <br />geometry of the failure surface beneath the slide mass. <br />3. Obtain geological data from cores and measurements of the orientation of <br />discontinuities (joints, bedding planes, faults) from field observations. Perform <br />stereonet analyses to determine the influence of discontinuities on the existing pit <br />slope failure or potential future slope failures. If applicable, characterize the rock <br />mass using "Hoek and Brown" parameters. <br />4. Perform a limit-equilibrium slope stability analysis and possibly a finite difference <br />(FLAC) analysis if applicable. Using various slope stability analysis methods, a <br />"back analysis" of the existing rock slide stability can be performed to determine <br />the strength parameters for the rock mass or the critical discontinuities in the pit <br />slope. <br />5. Using the back analyzed strength parameters, design mitigatory measures to <br />stabilize the failed slope and prevent future slope failures on other parts of the pit <br />slope. <br />Following Mr. Muller's explanation of the proposed monitoring and analysis, we <br />discussed some of the various hazards in placing survey prisms in the unstable slide <br />areas. Mr. Muller emphasized the experience of the people who would place the prisms <br />and the risks would be mitigated by prior monitoring and judgment. Mr. Gottheld <br />stated that the slope monitoring plan should include a detailed job hazard analysis. <br />Mr. Shafer stated that he would have new aerial photos and a topographic survey 1 <br />performed as soon as there was suitable weather. Mr. Muller recommended placing <br />large markers on the ground at the ends of all visible scarps and cracks so their <br />locations could be identified in the aerial photos.