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<br />i , <br />' 5.03 East Highwall Monitoring <br />Twenty-six surface survey points (numbered 2001 through 2026) were established to monitor <br />the effectiveness of the repair of the unstable slope on Bench 6 and 7. Positions of the <br />surface survey points have been determined by surveys conducted in March and May 1997, <br />March 1998, August 1998, and August 1999, which provide data to assess the performance <br />of the slide repair during 1998. Several survey points have been damaged by mining <br />activities. All the remaining points exhibited less than 0.15 ft of displacement from March to <br />August 1999, indicating stable slope conditions. <br />' 5.04 South End of Central Quarry <br />At the south end of the Central Quarry, the rock mass is typically poor. <br />' The rock mass structure is highly fractured and contorted with inconsistent jointing patterns. <br />The primary joint set is foliation joints in gneiss and schist rock. Foliation joint dip <br />' orientation varies as does the strike, but is generally southerly and into (or less frequently <br />westerly and parallel to) the slope orientation. Joint spacings typically range from several <br />inches to approximately 5 ft. Joint surfaces vary greatly from fresh to highly-weathered. <br />Weathered schist interbeds having a slick and weak character are frequent throughout [he <br />rock mass, and talc-like alteration is prevalent in this portion of [he quarry. <br />' At least two secondary joint sets are present, generally orthogonal to [he primary joint set. In <br />some cases, [hey cut through primary jointing and in some cases they terminate at a primary <br />joint. These secondary joints typically occur at intervals of one to five ft. In general, <br />secondary joint surfaces are fresher and less weathered than the primary joints along foliation <br />' and do not typically exhibit the smooth schist or mica surfaces. <br />Based on the conditions observed with the present exposures, the rock mass at the south end <br />of the Central Quarry is still classified as "poor" in terms of the previously established <br />baseline conditions. This classification is based primarily on the low strength of the parent <br />rock material, and also the presence of three joint sets and the low shear strength of some of <br />' [he joints due to the smooth surfaces and weathering. This classification may change as <br />additional rock is exposed at depth in this area. <br />' In general, the joint orientations are neither advantageous nor detrimental to slope stability. <br />Although the primary jointing is often advantageous (i.e. dipping into the slope), significant <br />variations exist and secondary jointing is often disadvantageous (dipping out of the slope). <br />Localized areas of instability were observed in temporary slopes and these conditions will <br />continue to be monitored during further development in this area. <br />' 5.05 West Side of the Central Quarry <br />The highwalls and benches are aligned at approximately NlO~W to N20~W, The rock type is <br />' primarily granite gneiss with mafic and felsic intrusions (felsite dikes and pegmatites). This <br />rock is primarily competent ruck (unconfined compressive strength greater than 15,000 psi) <br />with localized Zones of poor rock. <br />G \PFO)f(;T51?020U Mormm~ ~Juarrylg7N\IV99\newUthnarknp.dnc <br />1 <br />