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<br />. <br />. <br /> <br />I,Jwn Lake, 0(.'-39 <br />July 15, 1982 <br /> <br />Paye L <br /> <br />is shown in photo 19 , with ltS general location indicated In photo 18 <br />and zz,. This organic seam was tOLally saturated and free water was <br />released whcn a sample was squeezed. Soil temperature was between <br />35 and 40 degrees and the sod did dlsplay a slight degree of plasticity. <br /> <br />b. A relatively clean sand lense was found running through the dam above <br />the foundation, approximateiy 10 feet below crest elevation. This sand <br />seam was tota lly satucated and tne soil formed a "mud flow" when agitated <br />by foot. (See photo 20 and 18.) <br /> <br />c. A lense of peat was found running along the foundation of the dam <br />approximately 12 feet below crest elevation. Tree roots were growing <br />in this peat as shown in photo 21 and photo sequence 14 through 17. <br /> <br />Further getechnica 1 mapping and sampling is recommended. <br /> <br />4. Sand Plume Downstream of Dam. <br /> <br />A small sand plume had been depos ited on the natural ground immediately downstream <br />of the dam and to the right of the breach. Thls sand plume was on undisturbed natural <br />terrain approximately 13 feet above bottom of the existing breach. (See photos 23 <br />and 24.) The sand plume extended about 20 fee: downstream and varled from six to <br />12 feet to the right of the eroded channel. (See figure 4 for further description.) <br /> <br />It appears 'hat low velocity flows passed over the bench downstream of the dam prior <br />to the time that the eroded channel at the breach was formed. <br /> <br />5. Downstream Slope. Riqht of Breach. <br /> <br />The downstream slope to the right of the breach ls relatively steep and protected by <br />good grasses. There was evidence of past seepage along the toe of the dam and <br />at two distinct locations high on the embankment. At a point 60 feet to the right and <br />120 feet to the right of the current right s ide of the breach, there was evidence of <br />past. seepage through the embankment ash 19h as 5' 7" beiow the crest. In these <br />areas, the embankment was locally irregular with evidence of minor surface sloughing <br />and subsidence approxlmately six inches In depth. (See photo 1 for outiL,e of seepage <br />area.) . <br /> <br />A snowdrift remained near the right abutment of Lhe dam approxlrnately 30 feet cown- <br />s'ream from the toe. <br /> <br />6. Sand Plume, Left Slde of the Eroded Channel. <br /> <br />Starting at a point approximately 50 feet downstream from t he toe of the dam, a sand <br />plume exists on the bench to the left of thE: croued channel. (See photos 7 and 8.) <br />There was no evidence of low velocity flew at the toe of the dam at the left side of ~he <br />breach. <br /> <br />7. . Outlet <br /> <br />The following was observed ln regard to the outlet system: <br />