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Mining Methods and Slope Stability Evaluation for Expanded Development of the Walstrum Aggregate Quarry <br /> 4.0 RECOMMENDED SLOPE CONTROLS FOR THE WALSTRUM QUARRY <br /> Many factors influence the stability of rock slopes. Measures to protect slopes will also vary <br /> depending on the design life of the rock slope. For instance, air-decking or other slope-control <br /> blasting methods would be used to lessen damage to rock in final walls, whereas these methods <br /> would not be used in temporary bench walls. In this section, factors that will influence the stability <br /> of slopes at the Walstrum Quarry are identified and practical controls are recommended. <br /> 4.1 Wall Orientation and Mining Direction <br /> As indicated in the ISEE Blaster's Handbook (1998, p.314), when strata is dipping at a severe <br /> angle it is advantageous to develop working faces no less than 45 degrees to the down-dip <br /> direction of the strata. As shown in Figure 4.1 and historically demonstrated at the Walstrum <br /> Quarry, rock slope stability is improved when walls are oriented favorably with respect to dipping <br /> strata with potentially weak inter-layer cohesive strength. <br /> Controlled <br /> Back Break -- - - <br /> Stable Wall <br /> pljy <br /> Shooting Through The Dip <br /> Figure 4.1 —Improving slope stability by favorably orienting walls with respect to strata dip <br /> REVEY Associates,Inc. Page 7 of 14 October,2001 <br />