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-13- • Area II Foundation conditions in Area II were evaluated by drilling bor- ing No. 9 through 14. Foundation conditions encountered in these borings consisted of a very thin layer of very stiff clays over medium hard to hard claystone. The layer of clay ranged in thickness from 2 to about 5 feet. Claystones underneath the surficial layer were medium hard near the ground surface and became very hard at depths on the order of 10 to 15 feet. Unconfined compressive strengths in the under- lying materials ranged from 10,000 psf to nearly 22,000 psf. These unconfined compression tests are on samples obtained with a Calif- ornia drive type sampler. Samples were relatively undisturbed, however, our experience indicates that if core type samples are ob- • tained, the unconfined compressive strengths may even be higher than those indicated by these values. Penetration resistance tests were made at about 5-foot intervals in the borings in an attempt to confirm the results of the unconfined compression tests. In our opinion, the conditions that will exist in the bottom of the valley at disposal Area No. II will be very similar to the conditions encountered in disposal Area No. I and at the sedimen- tation damsite. We anticipate foundation conditions in this area to consist of a layer of softer clays ranging in thickness from 5 to 10 feet over the relatively unweathered clay stones. The hard clays and clay shales encountered on the higher dry slopes of the valley in disposal Area No. II have been pre-consolidated to high pressures and will compress slightly under the loads anticipated. • For purposes of stability analysis, we used C = 1,000 psf and