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relating to the shear strength of a gray, sandy silt. Accord- <br />ingly, the firm of Dames $ Moore was selected to provide a <br />third party analysis of the stability, subsequent to construc- <br />tion but prior to the dam's use as a tailings pond. They <br />reviewed the initial data developed during design and construc- <br />tion and further did their own field investigation, laboratory <br />testing, engineering analysis, and report preparation. It was <br />their opinion that "the existing embankment is stable and will <br />remain stable as tailings are deposited in the reservoir." <br />The Dames & Moore investigation did not center on problems of <br />seepage, but rather centered on the problem of stability re- <br />sulting from low shear strength material. <br />Analysis of the drilling logs contained in the Lincoln- <br />DeVoro, Francis-Meador-Gellhaus, and Dames $ Moore reports <br />provide valuable information on the geologic material supporting <br />the tailings dam. Bedrock in the area consists of the sandstones, <br />siltstones, and shales of the Creede formation, which is frac- <br />tured and locally faulted within the area. While some of the <br />reports indicate this material is "impermeable", the highly frac- <br />tured nature of the bedrock renders this a questionable conclusion. <br />The Creede formation is overlain with clays, silts, sands, <br />and gravels, derived from erosion of the Creede formation and <br />pre -Cambrian material located upgradient from the Creede forma- <br />tion. This is a very heterogeneous material, and was deposited <br />in a high energy environment. The old stream channels, consist- <br />ing of sands and gravels, cross the site north to south. For <br />example, Lincoln-Devore Testhole 4, located on the axis of the <br />-2- <br />