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-8- <br />• <br />intermediate, relatively soft clays will consolidate under the <br />loads of the proposed embankment. As the consolidation occurs, <br />the strength of the soils will increase. The most critical period <br />will be during construction when the minimum shear strength will be <br />available. The results of our laboratory tests, as well as the <br />penetration resistance tests, indicate that the shear strength of <br />these soils will be in the range of 1,000 to 2,500 psf. For pur- <br />poses of analysis of stability of the embankment during construction, <br />we recommend use of a maximum cohesive strength for the intermediate <br />clay layer of 700 psf. The residual shear strength on samples <br />obtained from Boring No. 4 at depths 9 to 14 feet indicate an <br />average residual shear strength of 1,200 psf. This test was per- <br />• formed unconsolidated, undrained, with multiple cycles of shear and <br />is probably representative of the lower bound of shear strength <br />available. <br />Borrow Soils <br />Four exploratory borings (TH-6, TH-7, TH-8, TH-9) were drilled <br />in the reservoir area in potential borrow areas. The soils encounter- <br />ed in these borings consisted of medium stiff, slightly sandy clays. <br />Eighty to ninety-five percent of the materials from the samples <br />passed the No. 200 sieve. Liquid limits on typical borrow soils <br />ranged from 32 to 46 and the plasticity index ranged from 18 to 29. <br />Standard Proctor compaction tests were made on bulk samples of these <br />soils to determine the compaction characteristics. For the proposed <br />• <br />