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-7- <br />• <br />tests are presented on Figs. 11 through 17. <br />Both the upper clays and the lower sedimentary rocks are rela- <br />lively impermeable, however, the sedimentary rock is considerably more <br />impervious than the upper clays. As a result, surface water flowing <br />through this area from natural drainage has developed a water table <br />over a long period of time. The depth at which water was encountered <br />is indicated on the boring logs and the time with respect to drilling <br />is also indicated. The method of advancing the boring many times <br />causes the water to seal at the time of drilling. The most reliable <br />observations are those made at least one day after the borings were <br />drilled. In general, the results of the borings indicate that in the <br />borrow area ground water will be encountered at depths of about 3 to 5 <br />• feet below the ground surface if no drainage is accomplished prior to <br />construction. Along the axis of the proposed structure, the depth to <br />water table was on the order of 8 feet at the time of our investigation, <br />except for Boring No. 5, which was located near the upstream toe of <br />the embankment. <br />Foundation Soils <br />An idealized picture of the foundation soils parallel to the <br />axis of the structure is presented on Fig. 3 and an idealized <br />description of the soil conditions at the maximum section perpen- <br />dicular to the axis are shown on Fig. 4 The foundation soils con- <br />sist of a layer of stiff clays, underlain by soft to medium stiff <br />clays over relatively incompressible sedimentary bedrock. The <br />r1 <br />U <br />