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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Geotechnical Engineering Investigation <br /> <br />VI. Conclusions and Recommendations <br /> <br />A. General <br /> <br />It is our opinion that Continental Dam's stability factors meet applicable standards, using <br />conventional limit equilibrium analyses, for most cases analyzed. In the cases where the stability <br />analyses do not fully meet applicable factors of safety, the results do not indicate that the dam is <br />likely to fail as the factors of safety are between 1.2 and 1.3. For example, in the case where the <br />exit point was considered at elevation 10,247 feet and the water level in the core was set at <br />reservoir elevation 10,267 feet, the corresponding factor of safety was 1.288. This case assumes <br />that the core is completely saturated to full reservoir pool elevation, a conservative assumption. <br /> <br />Based on the 1993 water level monitoring program ofCA-I, CE-l and CE-2 the phreatic <br />surface within the core and abutment did not reach these elevations, at least at the location of the <br />piezometers. The exact depth to the phreatic surface along other locations within the downstream <br />shell is not known and cannot be well established until a monitoring program of all piezometers <br />has been implemented. In the absence of a more complete monitoring program, the seepage and <br />stability cases we analyzed and their corresponding factors of safety provide the best available <br />guidelines for monitoring and evaluating the embankment's stability and perfonnance. <br /> <br />The finite element seepage analyses reinforces the fact that the embankment is generally <br />stable, based on the theoretical results that the phreatic surface is within the limits of these critical <br />elevations. <br /> <br />Based on these results, it is our opinion that the reservoir level restriction should be <br />temporarily lifted to allow a carefully controlled monitoring program to be conducted under <br />higher reservoir levels. This monitoring program is necessary in order to more clearly understand <br />the seepage conditions and to define if additional remedial efforts and analyses are needed at the <br />dam. <br /> <br />Our recommendations for a more complete monitoring program are presented in the <br />following section. The monitoring program should be implemented as a first stage in the <br />Continental Dam seepage mitigation to evaluate its long-tenn perfonnance and stability. <br /> <br />Continental Dam <br /> <br />Page 18 <br />