1998-03-26_GENERAL DOCUMENTS - M1973021

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' previously-established baseline conditions. Note that the term rock mass incorporates the parent rock material plus jointing and other characteristics which influence behavior of the mass. This classification is based primarily on the low strength of the parent rock material, but also on the three joint sets and the low shear strength of some of the joints due to the smooth surfaces and weathering. This classification may change as additional rock is exposed in this ' area. In general, the joint orientations are neither advantageous nor detrimental to ' slope stability. Although the primary jointing is often advantageous(i.e. dipping into the slope), significant variations exist and secondary jointing is often disadvantageous. Localized areas of instability were observed in temporary slopes and these conditions will continue to be monitored during further development in this area. ' Based on these observed conditions and on comparisons with baseline conditions for previous analyses, slopes at the south end of the Central Quarry are presently being excavated at an overall inclination of approximately I H:1 V or flatter. Furthermore, CAMAS intends to mine l H:1 V slopes in this part of the quarry as 40 ft highwalls and 40 ft benches, first, then evaluate going to ultimate 80 ft highwalls and 80 ft benches based on rock mass exposures and ' highwall performance of the smaller interim configuration. 5.4 North Quarry A. In general, the controlling primary joint set observed to date has been along foliation of the gneiss and schist rock. It has been observed to strike approximately N75'W which is approximately parallel with the ultimate orientation of the north wall, and dip 40 to 60 degrees south which is approximately perpendicular to and out of the north wall slope. Another foliation joint trend striking generally north and dipping generally west as observed in the East Highwall of the Central Quarry is also evident in the North Quarry. Folding- and shearing has created a series of small syncline and anticlines from approximately 20 to 100 ft across. As a result of these ' anomalies, the strike of the foliation joints varies by 45 degrees either direction from the predominant strike direction and the dip typically varies by 20 degrees or more. Joint spacings typically range from several inches to approximately three ft. Joint surfaces vary greatly from fresh to highly-weathered. Slick, weathered schist zones are frequent. B. At least two secondary joint sets are present, often orthogonal with the primary joint set. These secondary joints typically occur at intervals of one to five ft. In general, secondary joint surfaces are fresher and less-weathered than the foliation joints and do not typically exhibit the smooth schist or mica surfaces. C. A few large planar joint surfaces representing the primary joint set have been ' exposed as a result of wedges of overlying rock sliding on the joints. These surfaces have been as large as approximately I00-ft long by 60-ft high striking 11 G:\PROJECTS\-10200\002\97ANNRPT.WPF