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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 />o Uncontrolled seepage through the auxiliary spillway dikes. <br />o Inadequacies at the Chambers Lake inlet channel dike. <br />o Poor condition of the concrete service spillway. <br />o Sparse riprap slope protection on upstream face of dam. <br />o Undulations in dam crest. <br /> <br />2.0 GEOTECHNICAL EVALUATION <br /> <br />2.1 Field Investigation <br /> <br />2.1.1 General <br /> <br />The geotechnical field investigation at Barnes Meadow Dam was carried out to <br />supp1 ement work performed previ ous1y in the early 1970' s. The objecti ve was <br />to characterize the embankment dam and its foundation, investigate sources of <br />potential construction material, and to gather soil samples for laboratory <br />testing. The investigations consisted of surficial geologic mapping and <br />subsurface exploration by means of bore holes, test pits, and seismic <br />refracti on surveys. Standpi pe pi ezometers were install ed in each bore ho1 e <br />foll owi ng compl eti on. The work was performed duri ng July of 1987, di rectly <br />by, or under the supervision of, MKE personnel. <br /> <br />2.1.2 Geologic Mapping <br /> <br />A surficial geologic map of Barnes Meadow Reservoir is included in Figure <br />V.1. Barnes Meadow Dam and Spillway are founded on Quaternary glacial moraine <br />of Pinedale/Bull Lake Age, composed of clayey gravel till. The glacial till <br />contains large subrounded erratics to six feet in diameter. The flank of the <br />gl aci ated vall ey that ri ses above the south end of the reservoi r is composed <br />of metamorphi c and igneous rock of the Idaho Spri ngs Formati on, whi ch is of <br />Precambri an Age. Outcrops of ashey c1 aystone and sandstone from the Terti ary <br />White River Formation occur just to the west of Barnes Meadow Reservoir in the <br />vi ci ni ty of Chambers Lake. The north-south trendi ng Larami e Ri ver fault is <br />located approximately 1.5 miles west of the reservoir. <br /> <br />?ot-t..."l."-';.:L\\y <br />1\-(...~;....e.... <br /> <br />1231 H <br /> <br />-46- <br />