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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 />B. Groundwater <br /> <br />Groundwater was not encountered at the time of drilling in any of the boreholes. At that <br />time the reservoir elevation was about 10,240 feet. Water levels were also measured after the <br />installation of the piezometers. All measurements indicated no standing water in the piezometers. <br />It should be noted that fluctuations in the groundwater level is expected to occur due to reservoir <br />storage, degree of seepage along the left abutment, changes in seasons, variations in rainfall and <br />infiltration rates. <br /> <br />c. Seismicity <br /> <br />Earthquake intensities will vary depending upon the magnitude of earthquake, and the <br />distance of the project site from the causative fault. The site will likely be subjected to at least <br />one moderate earthquake that will cause ground shaking during its lifetime. We should note that <br />the scope of this report did not include a detailed seismicity investigation. The dam site is located <br />in seismic Zone 1 as shown on Figure 23-2, Seismic Zone Map of the United States, of the 1991 <br />Unifonn Building Code, UBC. The UBC recommended maximum ground acceleration from <br />earthquakes for this area is 0.075g. For the purpose of evaluating the pseudo-static embankment <br />slope stability a seismic coefficient ofO.075g was used in the stability analyses. <br /> <br />Continental Dam <br /> <br />Page 10 <br />