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<br />V. GEOTECHNICAL ANALYSIS <br />5.01 General <br />' Specific slope stability observations were conducted as required for mining activities performed <br />during 2005 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 2005 in the Central Quarry. Rather, observed general conditions were <br />compared with conditions observed previously. <br /> Tn 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 characteristics 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 are described in the following sections along with a summary of the geologic mapping <br /> performed on the apparent new final highwalls established in 2004. <br /> 5.02 Central Quarry <br /> For all four sides of the Central Quarry, conditions at the end of 2005 were observed to be <br /> consistent with those observed at the end of 2004. There appeared to be continued minor local <br />' instabilities and accumulation ofrocks and debris derived from highwalls on the benches. <br /> <br />However, no larger scale instabilities were observed. Details for the different sides follow. <br />i <br /> A. East Side <br /> <br /> <br /> <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. Due to <br />a three year measurement schedule, these points were not surveyed in 2005. <br />B. South End, North End, and West Side <br />No changes were observed in these areas during 2005. The overall slope in the south <br />end appears stable. There are localized areas of instability on individual benches due to <br />