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V. GEOTECHNICAL ANALYSIS <br />5.01 General <br />Specific slope stability analyses were conducted as required for mining activities performed <br />during 2003 in the North Quarry. Observed conditions were compared with conditions <br />identified in Technical Revision No. 3, which allowed for modification of the slope to steeper <br />than 1H:1V. <br />Specific slope stability analyses were not conducted nor required for mining activities <br />performed during 2003 in the Central Quarry. Rather, observed general conditions were <br />compared with conditions observed previously. <br />In Amendment No. 3, two rock mass conditions were identified for design purposes, and used <br />as the baseline for further evaluations. The two baseline conditions were "competent rock", <br />representing the majority of expected conditions, and "poor rock" representing localized areas <br />of shearing, weathering or adverse jointing. Note that the term rock mass incorporates the <br />parent rock material plus jointing and other characteristics that influence behavior of the mass. <br />Typical in-situ rock mass chazacteristics and the corresponding strength envelopes and <br />calculated safety factors for each of these baseline conditions were presented in Amendment <br />No. 3, Section 4-04. <br />The general ground conditions observed relative to the baseline conditions for each of the areas <br />' worked aze described in the following sections along with a summary of the geologic mapping <br />performed on the apparent new final highwall(s) established in 2003. <br />5.02 Central Quarry <br />A. East Side <br />The overall slope appears stable. As identified in previous geotechnical addenda, there <br />are localized areas of instability on individual benches. These typically occur where the <br />primary joint set strikes parallel with the slope and daylights out of the highwalls, and <br />where secondary joint set(s) occur and serve as detachment planes. Localized wedge <br />and slab slip surfaces were observed on the outside edges of individual benches. These <br />slip surfaces are infrequent and are relatively small, generally less than 10 feet in <br />length. These features are as expected for the highwall and only cause localized <br />operational inconveniences. <br />Twenty-six surface survey points (numbered 2001 through 2026) were established to <br />monitor the effectiveness of the repair of the unstable slope on Benches 6 and 7. <br />Positions of the surface survey points provide data to assess the performance of the <br />slide repair during 1998. Several survey points have been damaged by mining <br />activities. All the remaining points exhibited less than 0.04 ft of displacement from <br />Apri12002 to February 2004, indicating stable slope conditions. Survey information is <br />provided in Appendix A. <br />