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<br />, '" <br /> <br />,- <br />'.... <br /> <br />r:- <br />f .'. <br /> <br />" <br /> <br />7.2 Geotechnical Investigation <br /> <br />During the time that Task 2 is being carried out, the programs for field <br />expl ora ti on and 1 aboratory testi ng of embankment, foundati on, and potenti al <br />construction materials on the project shall be refined. Test holes have been <br />drilled at the Barnes l~eadO\~ site in the past and this information shall be <br />utilized to the maximum extent possible in defining the program. The scope of <br />the geotechnical investigation cannot be fully defined in this scope of <br />services, as it is extremely dependent on the results of the Task 2 site <br />inspections. A signficant amount of judgment shall be required in combining <br />drilling and test results with existing data to select preliminary design <br />parameters. <br /> <br />The rehabilitation solutions are centered around the structural stability of <br />the embankment and foundation. Seepage flows and seepage forces are of major <br />importance in carrying out stability analyses. Therefore, rluring the data <br />collection and review, field inspection and exploration, the objective shall <br />be to fully identify and investigate all characteristics of the dam and <br />foundation, and assess the observed seepage response during the 1987 season. <br /> <br />Vari ous methods of contro 11 i ng seepage flows sha 11 be i ncorpora tad into the <br />alternative designs for Barnes Meadow Dam. The treatment for seepage control <br />sllall be instrumental in the stability analysis. Analyses shall include a <br />detennination of the adequacy of in-place seepage control facil ities and the <br />need for additional seepage control measures. <br /> <br />General stability evaluations shall be made for the alternatives and a more <br />detailed analysis will be carried out for the feasibility design on this <br />project. The stability evaluation shall be perfonned for steady state, <br />seismic, and rapid drawdown loading conditions. <br /> <br />Compute,rized stability programs shall be used that employ the modified Bishop <br />method. These programs provide a search for the most critical failure circle <br />for the conditions selected. Variables of embankment and foundation strength, <br />seepage flow line, draw down conditio~ and seismic loads shall be selected <br /> <br />- 7 - <br />