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<br />" <br /> <br />. <br /> <br />. <br /> <br />Mainstem Sites - Four to five rotary holes shall be drilled along the <br />dam centerline of each of the selected sites. Generally, subject to the <br />results of surficial mapping, there shall be two holes on each abutment <br />and one in the narrow canyon bottom. The boreholes on abutments may be <br />angled so that maximum information can be obtained on the attitude of <br />discontinuities in the rock mass. The holes shall be extended to a <br />depth sufficient to detect any potential problems within the foundation, <br />correspondent to the size of the proposed structure. <br /> <br />One or two holes shall be drilled on the centerline of any potential <br />side channel spillways and holes shall also be drilled at the upstream <br />and downstream toe of the proposed dam. These holes shall be drilled <br />only to determine the top of sound rock and are to be used in <br />conjunction with seismic refraction lines to fully define the top of <br />rock along the dam axis, perpendicular to the centerline down the river <br />channel, and along the centerline of any side channel spillway. <br /> <br />Holes will be drilled as necessary to prove or disprove the existence of <br />landslides along the south side of the river by these sites. At least <br />one test pit shall be excavated in the alluvial bottom of the dam <br />foundation to obtain samples for laboratory testing. <br /> <br />Powell Park - Four to five rotary boreholes shall be drilled along the <br />centerline of the selected axis. Four holes shall be drilled in the <br />flood plain and in the gently sloping right abutment. One hole shall be <br />drilled on the bedrock plateau that is the left abutment. The hole on <br />the left side shall be angled to maximize the information that can be <br />gained. Two holes shall be drilled to rock along the centerline of the <br />potential spillway site on the left abutment and one at the upstream and <br />downstream toe of the proposed dam. Seismic refraction lines shall be <br />conducted along the centerline of the dam and perpendicular to the axis <br />at three or four points along that line. The purpose is to fully define <br />the top of the foundation profile between drill holes. <br /> <br />A-9 <br />