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Update on Kinematic Stability of Individual Benches <br /> Individual bench stability is controlled primarily by the orientation of joints relative to the orientation of <br /> the highwalls. Along the western side of the Central Quarry, the primary joint system which parallels <br /> the foliation of the rock mass generally dips favorably into the slope. Geologic mapping and stereonet <br /> plotting of these joints determined an average orientation of N10°W, 24°W with some data scatter due <br /> to folding. The Western Highwall is oriented essentially parallel at N10°W. Based on this condition, <br /> no systemic bench instabilities were observed due to the primary joint system. <br /> Secondary joint sets are prevalent throughout the rock mass and were also mapped in the field. These <br /> secondary joint sets are expected frequently oriented perpendicular to the primary joint set, but also occur <br /> randomly. These secondary joint sets are expected to result in small localized block and wedge failures <br /> of individual benches. Observations and mapping of the highwall above the bench at El. 6,560 ft and <br /> the highwall below indeed reveal a few localized instabilities. In total these localized instabilities account <br /> for less than ten percent of the total bench area and presently do not adversely affect the proposed <br /> reclamation, the integrity of the benches, or Cooley's operations. <br /> SUMMARY AND CONCLUSIONS <br /> Development of Cooley's Morrison Quarry is continuing in general accordance with the approved mine <br /> plan. <br /> In accordance with the Observational Method presented and approved in the permit amendments, the <br /> lowest bench along the western side of the central quarry was changed from a width of 80 ft to 40 ft. <br /> At this location rock conditions were evaluated from field explorations and laboratory testing, and these <br /> conditions were compared with previously determined baseline conditions. These comparisons revealed <br /> stable slope conditions. <br /> Localized adverse jointing of rock in benches and highwalls has resulted in the isolated incidence of <br /> blocks and wedges dislocating from the highwalls at the outboard edges of benches. These occurrences <br /> have resulted in reductions in bench area by approximately ten percent or less on the average. This <br /> condition was expected to occur on a limited basis and is not expected to impair remediation or Cooley <br /> operations. The methods of mine development, blasting, excavation, and evaluation used to date have <br /> been effective in controlling slope stability. <br /> During the 1994 calendar year for which this Annual Report addendum was prepared, work had not <br /> began on remediation of the East Highwall. In 1995, remediation of the East Highwall began. As of <br /> 1 March, 1995, the upper two benches (Elevations 6760 and 6720) had been excavated. Excavation is <br /> continuing from the top down and Cooley is having both Haley & Aldrich and Benchmark Surveying, <br /> Ltd. monitor the progress on a bench by bench basis to ensure ongoing geotechnical stability input and <br /> to provide survey control for the highwalls and benches. Results of this ongoing work will be presented <br /> with the 1995 annual report. <br /> RP08267.200 8 <br />