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' VI. SUMMARY AND CONCLUSIONS <br /> Development of Cooley's Morrison Quarry is continuing in general accordance with the <br /> approved Mine Plan. Mining is continuing at the south end and east side of the Central <br /> Quarry and in the North Quarry in accordance with the Observational Method presented and <br /> approved in the permit amendments. <br /> ' Excavations performed during 1996 do not generally reflect the ultimate, final quarry walls, <br /> except at the upper four highwalls of the east side of the Central Quarry. Excavation of the <br /> East Highwall for the Central Quarry is progressing as planned with ground conditions similar <br /> ' to those assumed for the baseline stability condition, except for a localized failure which <br /> occurred in late January 1996. This failure was investigated and repaired during the Spring <br /> of 1996 and the investigation data and a discussion of geotechnical analyses leading to the <br /> ' repair are included in this annual geotechnical addendum. The width of the fourth bench was <br /> decreased to accommodate the existing geometry of older, previously mined benches revealed <br /> during this year. This will allow the remaining benches and highwalls yet to be mined to <br /> better fit existing slope conditions. A network of survey monuments for monitoring potential <br /> slope movement was installed for the repaired slide area. The repaired slope remained stable <br /> throughout the remainder of 1996. <br /> ' Due to a relatively weak unweathered rock material at the south end for the Central Quarry, <br /> benches and highwalls are presently being excavated no steeper than 1H:1V. Interim slopes <br /> ' are being developed at a configuration of 40 ft highwalls and 40 ft benches, with 80 ft by 80 <br /> ft interim highwalls and benches developed locally. <br /> In the North Quarry, benches and highwalls are presently being excavated no steeper than <br /> 1H:1V. This slope configuration is due to the weak rock within the weathered zone near the <br /> ground surface and adverse joint orientation. Present excavations do not reflect the ultimate <br /> ' slope configuration for the quarry. <br /> Localized adverse jointing of rock in benches and highwalls has resulted in the isolated <br /> occurrence of blocks and wedges dislocating from the highwalls at the outboard edges of <br /> ' benches. This condition will probably continue to occur and will be monitored and evaluated <br /> on a case-by-case basis. The methods of mine development, blasting, excavation, and <br /> evaluation used to date have been effective in controlling slope stability within expected <br /> ' parameters. <br /> ' 18 G:\PROJECTS\20200\002\96ANNRPT.WPD <br /> '® w <br />