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<br />'~~ <br />, <br /> <br />Woodward-Clyde <br />Consultants <br /> <br />will include a combination of selected profile plotting and contouring of all SP results <br />with interpretation of seepage patterns. <br /> <br />2.2.4 Drilling, Sampling, and Field Testing <br /> <br />The proposed drilling program consists of four boreholes. Three are located on the <br />existing dam crest and one at the downstream toe on the right abutment. The purpose <br />of the drilling program is to determine the subsurface stratigraphy, engineering <br />classifications, and engineering properties for the materials in the embankment and its <br />foundation. Samples of these materials will be taken at selected intervals and depths for <br />field classification purposes and later laboratory testing. Field permeability tests using <br />borehole packers and flow meters will be conducted at various depths in selected <br />boreholes to evaluate the relative permeability of the various strata. The test results will <br />be used to develop a conceptual model of the possible subsurface flow patterns which <br />are possibly related to the historical sinkhole development. If water losses during the <br />permeability testing are large, dye injection tests may be conducted at selected depths <br />in an attempt to determine the flow path(s) and possible outlet points. <br /> <br />The proposed boreholes are located either on the dam crest or at the downstream toe. <br />The borehole pattern will be refined based on the results of the site inspection and <br />surface geophysical investigations to maximize the efficiency and minimize the costs of <br />the drilling program. Borehole depths are expected to range from 40 to 60 ft with a <br />maximum embankment penetration of approximately 30 ft and a maximum foundation <br />penetration of approximately 50 ft. Standpipe piezometers will be installed in selected <br />boreholes located along the dam crest to allow monitoring of water levels and water <br />temperatures within the dam foundation and embankment. <br /> <br />Special emphasis will be placed on the sampling of clays, claystones, and shales in the <br />lower embankment and foundation as these materials, if classified as dispersive or <br />susceptible to slaking, may be contributing significantly to sinkhole development. <br /> <br />92D217PI?1:7 06-15-Q2(1 0: 17pmI/PROJ.54 <br /> <br />-6- <br />