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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 />An alternlltive for each dam section <br />considered includes the construction of an <br />upstream core trench. We do not consider the core <br />trench to be mandatory but it is good engineering <br />practice and should be strongly considered. The <br />state Engineer'~ Project Manual requires the <br />seepage be controlled but does not require this to <br />be done with a core trench. The cost of a core <br />trench can usuallY be justified based on increased <br />safety and minimization of water loss. For the <br />alternative dam, a cutoff trench is not an <br />alternative but is mandatory due to the foundation <br />conditions being unknown. <br />A toe drain is shown for installation at the <br />dam toe for all alternatives considered. We <br />consider the toe drain to be mandatory for the <br />stability of tbe dam and is not considered <br />optional. The toe drain is required based on our <br />engineering analysis and based on requirements in <br />the state Engineer's proj ect Manual that seepage <br />be controlled. combined with the toe drain, with <br />repair of the existing dam, is a sand blanket <br />between the existing fill and berm fill. This <br />blanket is also considered to be mandatory to <br /> <br />V-7 <br />