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<br />. <br /> <br />58 <br /> <br /> <br />0=1841 <br /> <br />. <br /> <br />. <br /> <br />location of drill holes and the logs of the formations encountered. <br /> <br /> <br />The total drilled is 788 feet.. Eliminating overburden, a total core <br /> <br /> <br />recovery of 80./+% was obta.ined from 649 feet of drilling, vlith the <br /> <br /> <br />deepest hole being in the left Qbutment to a depth of 200 feet. <br /> <br /> <br />A cut-off through the terrace gravels at the south abutment <br /> <br /> <br />is neceSSQry for vlilter tightness. 1ev.kage through the bedded forma- <br /> <br /> <br />tions will be negligible since percolQtion tests show about 5 gallons <br /> <br /> <br />per minute with lOO pounds pressure. In no instance did the rate <br /> <br /> <br />exceed l7 gallons per minute. <br />Two abandoned c09.1 mine sh,.fts lit3 in the vicinity of the <br />right n.butment". Though surface examinations seom to incHcate that <br />these mino workings nre small, it is possible that they undermine <br />ground pertinent to the south rebutment. <br />From the explorations, tho foundQtions and abutments are <br />conc1uued .to be suitable for ererth dLem construotion of the hoight <br />contemplated, or for re low concreto or masonry dam. <br /> <br />The Dam <br /> <br />This is an earth- Lmd rock-fill emb"nkment (see drawing <br /> <br /> <br />256-D-l45), 35 feet wide on top Llt elevation 6290, with a 2i;l up- <br /> <br /> <br />stream slope from the top to elevation 6240 belov! which tho slope is <br /> <br /> <br />3:1, cmd L, 2:1 uovmstream slope to G 20-foot berm at elevation 6220, <br /> <br /> <br />continuing on a 3:l slope to the river bed. <br /> <br /> <br />The upstream slope is protected by Cl 3-foot blanket of <br /> <br /> <br />dumped rock riprccp. Tho portion of the d"-m ..lith a 5-foot top v,idth <br />