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<br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />I <br />1 <br />1 <br />1 <br />1 <br />1 <br />I" <br />;, ,...., <br />1 <br />1 <br />1 <br />1 <br />1 <br /> <br />II DESIGN REVIEW <br /> <br />A. Abutments <br /> <br />Density. As noted in Section I, the geology of the damsite and reservoir <br /> <br />area indicates that the abutments have been preconsolidated by glacial load-, <br /> <br />ing and presaturated by former lake levels and annual high water tables. The <br /> <br />density of the insitu materials was evident in the open test pits inspected <br /> <br />on both abutments on August 23, 1978. While nuclear density test results <br /> <br />being taken in the pits were not available for review, previous insitu test <br /> <br />results can be compared with laboratory compaction tests, For example, dry <br /> <br />densities in test pits 101, 102, 103, and 104 on the left abutment range from <br /> <br />106 to 122 pounds per cubic foot and average 113. The laboratory maximum <br /> <br />dry density of 116 pounds per cubic foot from test pit 102 indicates an insitu <br /> <br />dry density corresponding to 113 x 100 or 97% relative compaction (Standard <br />116 <br />Proctor). This density is comparable to that required for the embankment and <br /> <br />is considered entirely adequate for the embankment slopes which will abut <br /> <br />against these materials. While data for a similar comparison on the right <br /> <br />abutment were not available, the penetration test results are similar for <br /> <br />both abutments and indicate increasing density with depth. <br /> <br />Gradation. The gradation tests presented in the "Geotechnic Data" report <br /> <br />for test pits 102, 203, and 105 were assumed to be representative of the <br /> <br />Zone 1, Zone 2, and foundation materials, respectively. The morainal materials <br /> <br />from the borrow area and the foundation (test pits 203'and 105) are very well <br /> <br />graded and the fines moderately plastic. As the right abutment is also mor- <br /> <br />ainal, similar gradation could be expected, The left abutment material, to <br /> <br />be used for Zone 1 construction, (test pit 102) has very little sand but <br /> <br />is otherwise well graded, <br /> <br />Plasticity. In general, fines from the left abutment tests are more <br /> <br />plastic than those from the right abutment or borrow area, The Plastic <br /> <br />Indices (PI) for left abutment tests average 11.5 vs 8.5 for the right <br />