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-12- <br />n <br />U <br />weathered clays tone over hard claystone. We anticipate foundation <br />conditions on the ridges will be similar in all of the proposed <br />disposal areas. In the valley areas where drainage is not well <br />developed, a combination of soils being washed from the higher <br />areas and in-place weathering has resulted in a layer of clay <br />which ranges in thickness from 6 to 18 feet. The material has been <br />softened by moisture and is considerably more compressible than <br />the underlying bedrock. The results of swell-consolidation tests <br />on typical samples of this clay are presented on Figs. 20 through 28. <br />The unconfined compressive strength for the stiff clays was es- <br />timated to be on the order of 4,000 to 8,000 psf, based on the <br />results of field penetration resistance tests. The softer clays <br />• have unconfined compressive strengths in the range of 2,000 to 3,000 <br />psf. Our estimate of strengths include results of tests made for <br />the sedimentation dam in similar materials. <br />Direct shear tests were made on stiff clay and weathered clay- <br />stone samples obtained from borings No. 1 and No. 13. The results <br />from boring No. 1 indicate a peak shear strength 0 of 20 degrees <br />and C of 2,000 psf. The test results from boring No. 13 indicate <br />a ~ of 12 degrees and C of 2,000 psf. Based on the results of un- <br />confined compression tests, Che strength of the near-surface clays <br />was assumed to be Q = 0 and cohesion of 1,000 psf. The near-surface <br />bedrock was assumed to have strengths corresponding to 5,000 psf C <br />and ~ of 15 degrees. <br />n <br />LJ <br />