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<br />. <br /> <br />. <br />(j <br /> <br />. <br /> <br />'2.1 <br /> <br />()72f; <br /> <br />c. The alluvial material upstream on the right abutment and <br />adjacent to the dam should not be removed since this could <br />expose the more permeable material to the reservoir. <br /> <br />d., The Pierre formation on ,the left abutment should be thoroughly <br />tested to determine its soundness and reaction to saturation. <br />Slaking and softening could be investigated by ponded test pits. <br /> <br />e. The erodibility of the Pierre fo~tion, which will be <br />exposed to the structure cuts, should be studied. <br /> <br />f. Determine the collapse potential of the surficial materials <br />of the right abutment upon saturation. <br /> <br />g. 'The conditions assumed for the steady-state seepage analysis; <br />namely, steady-state flow ,conditions at m~~imum flood surface, <br />are very conservative and may lead to unnecessary provisions for <br />seepage and uplift controls. <br /> <br />h. The transient-state seepage analysis should be used to <br />determine the need for seepage and uplift controls. <br /> <br />i. The slurry trench must bottom on the Pierre formation. <br /> <br />j. Pressure relief wells could provide a safe exit gradient' <br />for seepage. <br /> <br />6. <br /> <br />Additional final design investigations suggested by Sowers: <br /> <br />a. Investigate shrinkage characteristics of core material. <br /> <br />b. Investigate expansion of plastic clay core material. <br /> <br />c. Consider use of less plastic materials above joint use pool <br />to reduce shrinkage. <br /> <br />d. Examine full range of possible soil strengths in embankment <br />and foundation. <br /> <br />e. Sowers, assuming that there is a limited amount of zone 1, <br />questions the use of such a wide core. <br /> <br />7. Additional final design investigations suggested by Coombs: <br /> <br />a. , Windblown silt, gravelly sand, and clayey silt and sand on <br />top of weathered formation on the left abutment may present <br />slump problems. <br /> <br />:; <br />