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i <br />no significant water pressure would build up within the waste • <br />~ dump fill. The results of the analysis and basic geometry <br />assumed are shown on Figure 3. In general, lift thickness <br />( on the order of 50 feet appear reasonable. <br />We briefly considered the possibility of the waste dump <br />t stability being controlled by the strength of the waste dump <br />fill or residual soils. Based on our evaluation in conjunc- <br />tion with work done by LYahler Assoc., the general slope stability <br />will be controlled by the much lower strengths of tl~e colluvium/ <br />alluvium soils. <br />1Ye also considered the consequences of a slope failure. <br />In essence, our explorations and analysis only apply specifically <br />to the valley bottom within the small western edge of the final <br />L- waste dump. Although this area will receive most of the initial <br />waste dump material, it represents a very small portion of they <br />total waste dump area. Other areas are underlain by more com- • <br />petent soils and would be more stable. Also, the waste dump <br />I_ material is a well graded coarse granular material and clearly <br />is not the type of soil which would normally be subjected to <br />liquification or a sudden strength loss. In addition, the <br />general geometry of the final fill limits would tend to <br />confine the waste dump and add further to the stability. <br />Thus, in our opinion, a major slide reaching State Highway <br />13 is extremely unlikely even under adverse conditions. <br />~_ <br />5.0 I<1INE SUBSIDENCE EVALUATION <br />~. _ <br />Collapse of the underground mine due to the surcharge <br />by the dump in the critical area of Streeter Canyon itself <br />(i.e. to the east of 6,900 contour of a 4:1 dump configura- <br />tion) is extremely unlikely. This is because the Red Lying <br />Mine in this particular area is dominately located under the <br />L_ • <br /> <br />