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I~ V. GEOTECHNICAL ANALYSIS 5.01 General Specific slope stability analyses were conducted and required for mining activities performed ' during 2002 in the North Quarry. Observed conditions were compared with conditions identified in Technical Revision No. 3, which allowed for modification of the slope to steeper than 1H:1V. Specific slope stability analyses were not conducted nor required for mining activities performed during 2002 in the Central Quarry. Rather, observed general conditions were compared with conditions observed previously. In Amendment No. 3, two rock mass conditions were identified for design purposes, and used as the baseline for further evaluations. The two baseline conditions were "competent rock", representing the majority of expected conditions, and "poor rock" representing localized azeas of shearing, weathering or adverse jointing. Note that the term rock mass incorporates the parent rock material plus jointing and other characteristics that influence behavior of the mass. Typical in-situ rock mass characteristics and the corresponding strength envelopes and calculated safety factors for each of these baseline conditions were presented in Amendment No. 3, Section 4-04. The general ground conditions observed relative to the baseline conditions for each of the azeas worked are described in the following sections along with a summary of the geologic mapping performed on the new fmal highwalls established in 2002. 5.02 Central Quarry A. East Side The overall slope appears stable. As identified in previous geotechnical addenda, there are localized areas of instability on individual benches. These typically occur where the primary joint set strikes parallel with the slope and daylights out of the highwalls, and where secondary joint set(s) occur and serve as detachment planes. Localized wedge and slab slip surfaces were observed on the outside edges of individual benches. These slip surfaces are infrequent and are relatively small, generally less than 10 feet in length. These features are as expected for the highwall and only cause localized operational inconveniences. Twenty-six surface survey points (numbered 2001 through 2026) were established [o monitor the effectiveness of the repair of the unstable slope on Benches 6 and 7. Positions of the surface survey points provide data to assess the performance of the slide repair during 1998. Several survey points have been damaged by mining activities. All the remaining points ' exhibited less than 0.01 fr of displacement from August 2000 [o April 2002, indicating stable slope conditions. Survey information is provided in Appendix A. ' B. South End, North End, and West Side The overall slope in the south end appears stable. There are localized areas of instability on ' individual benches due to "poor" rock mass conditions. Localized areas of instability were G:\PROI ECTS\20200 Morrison Quarry\008\2002\2002 geotechnical adderidum.doc