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<br />I <br />,~ <br />I <br />I <br /> <br />c' n 'J' e, <br />v,J d <br /> <br />embankment dam c::m be constructed on it. The simplicity of the questton, unfortunately, <br />Is such that the inference might be drawn that a simple "yes" or "no" answer should <br /> <br />ensue. <br /> <br />On the broadest and most general of bases, we do not hesitate to affirm that, <br />despite the difficult foundation conditions at the site. and the less than high quality em- <br />bB.Dkment materials available nearby for construction of a dam of the height and length <br />contemplated, currently available engineering 3ILd geologic experience and knowhow [s <br />sufficient to develop a safe, reliable design. The challenge Is to so apply that knowhow, <br />In a fully integrated fashion to a multIplicIty of engineering and geologic details. as to <br />develop a flnal desIgn that Is so modifIed from mlle to mUe along the axls of the dam as <br />to be fully defensive against any credible fOlmdation defect of such nature as to threaten <br />the performance of the darn. In our judgment, the FeasibiUty Design, Figure 2, does <br />not fully achieve that goal. Modlfications to that design, which we understand are cur- <br />renUy being favored by some USBR designers, such as addition of an internal gravel <br />drain downstream from the core zone, and addition of relief wells along part of the <br />downstream toe of the dam, would greatly lmprove the safety aspects of the FeasibIlity <br />Design. Other measures which we believe would merit consideration in the USER's de- <br />sIgn of the dam will be set forth in the following section of this report. IncIdentally. <br />we do not conclude that relIef wells are either useful or necessary at thls dam. <br />SPECIFIC COMil1ENTS <br /> <br />Successful design of a dam, especIaUy for one on a very long and comple.x site <br />and on a very large river, requires a balanced consideration of the inter-relationships <br />of many engineering and geotechnical dIsciplines. Those that we consider to be partic- <br />ularly Important to the question directed. to us are discussed under the following head- <br />ings: <br /> <br />I, Hydrology, <br />2. Reservoir Operation. <br />3. FOlmdation Condltions. <br /> <br />a. Left Abutment and Riverbed. <br /> <br />:J.r <br /> <br />b. <br /> <br />Right Abutment - Slurry Trench Reach. <br /> <br />7, <br />