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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 />e(' <br /> <br />. <br /> <br />-4- <br /> <br />southern abutment will be on an older alluvial terrace about 40 <br /> <br /> <br />feet above the stream (symbol Qlo on The Geologic Map). The boring <br /> <br /> <br />tends to confirm the alluvium thickness reported by Scott. <br /> <br />Discussion <br />In our opinion, future investigations will confirm that a <br />properly designed dam can be ~onstructed at this site. The pro- <br />posed dam site has no soil or geology problems that cannot be <br />resolved during design. <br />The foundation soils and rock will, in our opinion, provide <br />adequate support for an earth dam. Considering the abundance of <br />pervious soils in the reservoir area, the dam design will very <br />likely involve some zoning of materials. It may be necessary to <br />go beyond the reservoir area to obtain sufficient fine grained soils <br />(clays) for construction of a seepage cutoff trench. <br />Seepage losses likely, will be high without a foundation cutoff <br />extending into the underlying bedrock. (It appearS that this is <br />the only factor in our field which could affect the feasibility <br />of the site for the planned dam). If high seepage losses cannot <br />be tolerated, then a cutoff trench to bedrock will likely be <br />necessary. <br />We believe the gravels and cobbles encountered in the boring, <br />and likely present beneath the entire dam, will prove to be Quite <br />pervious while the underlying bedrock we expect to be relatively <br />impervious. Assuming the thickness of the pervious materials (gravel <br />cobble layers) in the boring is representative and constant and <br />further assuming permeability values reported as typical for <br />