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_ 7.2 Geotechnical Investigation <br />During the time that Task 2 is being carried out, the programs for field <br />exploration and laboratory testing of embankment, foundation, and potential <br />construction materials on the project shall be refined. Test holes have been <br />drilled at the Barnes Meadow 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 />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, during the data <br />collection and review, field inspectio ploration, the objective shall <br />be to fully identify and investi� a ch a istics of the dam and <br />foundation, and assess the observed age j uring the 1987 season. <br />Various methods of controlling se,,x'fler�is shall be incorporated into the <br />i;.r F <br />alternative designs for Barnes Mead °off -Dam. The treatment for seepage control <br />shall be instrumental in the stability analysis. Analyses shall include a <br />determination of the adequacy of in -place seepage control facilities and the <br />need for additional seepage control measures. <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 performed for steady state, <br />seismic, and rapid drawdown loading conditions. <br />Computerized 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 conditiong and seismic loads shall be selected <br />- 7 - <br />