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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 />results of this evaluation were input into analysis to verify the stability of <br />the dam. The results were also utilized to assess the properties of the local <br />materials in order to formulate alternatives for rehabilitation of the <br />observed deficiencies. <br /> <br />The field work consisted of surficial geologic mapping and subsurface <br />exploration by six rotary boreholes, five test pits, and 1,300 linear feet of <br />sei smic refraction survey. Laboratory testi ng of samp1 es obtai ned from the <br />boreholes and test pits consisted of visual classification, sieve analysis, <br />p1 asti ci ty characteri zati on, compacti on properti es, and. permeabil i ty. In <br />addition, tests for durability were perfonned on samples of material with <br />potential as concrete aggregate. A trial mix of roller compacted concrete was <br />also prepared and tested. <br /> <br />The results of the geotechnical investigation showed the upper eight to ten <br />feet of the dam, correspndi ng to the rai sed secti on, to be composed of dark <br />brown, moderately dense, silty sand with gravel and cobbles. The original dam <br />is composed of light gray, dense, silty to clayey sand with occasional <br />cobbles. It appeared from the subsurface exploration that the finer-grained <br />Zone I I impervi ous fi 11, added in 1973, may not have been carri ed to the dam <br />crest as shown on the "as built" drawings. <br /> <br />A test pit in the emergency spi 11 way showed the ri prap to be sati sfactory. <br />The boreholes showed the contact between the embankment dam and foundation to <br />be marked by a thi n 1 ayer of organi c materi a 1. The upper ten feet of the <br />foundation appeared to contain more fines than the embankment or the <br />underlying foundation. <br /> <br />The area downstream of the dam is covered by approximately four feet of <br />recently placed random fill overlying about one foot of organic soil. <br /> <br />As the reservoir was full at the time of the investigation.. it was impossible <br />to sample potential borro'd areas within the reservoir. It was assumed that <br />si nee the dam was constructed with local materi a1 s, additi ona1 quanti ti es of <br /> <br />E-5 <br /> <br />1151c <br />