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<br />'. <br /> <br />,- <br /> <br />,I <br /> <br />,-"......" <br /> <br />"",-f.,,.;:,,," <br />:7.~ .;:.',:' .'. ~-'~~ <br /> <br />I1KE shall drill seven boreholes with an emphasis on gathering as much <br />Information as possible from each hole, In this way, the previous boreholes <br />can be correlated and conclusions can be drawn as to embankment <br />characteristics and patterns. Four of the holes shall be drilled f.rom the <br />crest of the dam through the embankment and into the foundation, An attempt <br />shall be made in at least one of these holes to reach bedrock. Two additional <br />holes shall be drilled downstream of the maximum section of the dam, wi~h one <br />hole located to either side of the outlet, An attempt shall be made to <br />determine and verify the depth of bedrock downstream of the dam, Utilizing <br />the information obtained from these holes and the holes drilled from the <br />crest, an estimate of the bedrock elevation beneath the maximum section of the <br />dam shall be made by interpretation of the drill hole data, A seventh drill <br />hole shall be located in the area of the primary and secondary spillway dike, <br />This hole shall be drilled from the crest of the dike, with an attempt made to <br />advance the hole to and into bedrock, <br /> <br />The boreholes shall be systematically sampled by the split spoon or California <br />method at 5-foot intervals. or where changes in material are detected. <br />Standard penetration tests shall be conducted when samples are taken, <br />Borehole permeability tests shall be performed every ten feet to determine the <br />distribution of more or less pervious strata, Undisturbed samples shall be <br />obtained of the embankment and foundation, as required for classification In <br />the laboratory, and detennination of strength characteristics for use in the <br />stability and seepage analyses. In the event one or more of the boreholes <br />does reach bedrock, it shall be cored and packer-tested to a depth of at least <br />ten feet, Upon completion of a borehole, multiple stage, standpipe piezometers <br />shall be installed in strata of varying permeability within the hole in order <br />to allow measurements of the phreatic surface, In addition, several test pits <br />and trenches will be e.cavated on and around the dam to correlate the physical <br />characteristics of the embankment and the foundation with the samples obtained <br />from drilling, where a particle size restriction exists. Test pits shall also <br />be used to assess the thickness of riprap and the qual ity of the upstream <br />impervious blanket, I~ addition, seismic lines shall be run along the crest <br />of the dam in order to defi ne the dam/foundati on contact and the top of <br />bedrock, <br /> <br />- g - <br />