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temporary slopes and these conditions will continue to be monitored during <br /> P rY P <br /> further development in this area. <br /> Based on these observed conditions and on comparisons with baseline <br /> conditions for previous analyses, slopes at the south end of the Central <br /> ' Quarry are presently being excavated at an overall inclination of <br /> approximately 1H:1V or flatter. Furthermore, during the 1996 mining year, <br /> Haley &Aldrich has recommended to CAMAS that 111:1V slopes be <br /> ' constructed in this part of the quarry as 40 ft highwalls and 40 ft benches, <br /> first, then evaluate going to ultimate 80 ft highwalls and 80 ft benches based <br /> on rock mass exposures and highwall performance of the smaller interim <br /> configuration. <br /> 5.4 North Quarry <br /> A. The rock material within 20 to 50 ft of the original ground surface is highly <br /> weathered. The degree of weathering decreases with depth. Additionally, <br /> ' zones of brecciated rock were observed. Within the weathered zone, the rock <br /> is estimated to have an unconfined strength less than 15,000 psi and in some <br /> highly-weathered and brecciated zones, less than 2,000 psi. Weathering is <br /> ' more pronounced in the schist zones than in the granite and gneiss zones of <br /> the formation. <br /> B. The primary joint set is along foliation of the gneiss and schist rock. It strikes <br /> N751W which is approximately parallel with the ultimate orientation of the <br /> north wall, and dips 60 degrees south which is approximately perpendicular to <br /> ' and out of the north wall slope. Folding and shearing has created a series of <br /> small syncline and anticlines from approximately 20 to 100 ft across. As a <br /> result of these anomalies, the strike of the foliation joints varies by 45 degrees <br /> ' either direction from the predominant strike direction and the dip typically <br /> varies by 20 degrees or more. Joint spacings typically range from several <br /> inches to approximately three ft. Joint surfaces vary greatly from fresh to <br /> highly-weathered. Slick, weathered schist zones are frequent. <br /> ' C. At least two secondary joint sets are present, often orthogonal with the <br /> primary joint set. These secondary joints typically occur at intervals of one to <br /> ' five ft. In general, secondary joint surfaces are fresher and less-weathered <br /> than the foliation joints and do not typically exhibit the smooth schist or mica <br /> surfaces. <br /> ' D. At the base of the north slope exposed at the end of 1995, a large planar joint <br /> surface was exposed as a result of a wedge of overlying rock sliding on the <br /> ' joint. This surface was approximately 100-ft long and 60-ft high, had a strike <br /> of N750W approximately parallel with the slope, and dipped 551 south <br /> which was out of the slope. On a large scale, the surface was planar but local <br /> ' variations created an undulating surface with variations in strike and dip by <br /> 20 degrees. In response to such occurrences with a south to north mining <br /> ' 16 G:\PROJECT'S\20200\002\96ANNRPT.WPD <br /> '® s <br />