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<br />combination of these two soils was noted. Standard Proctor test were run on <br />the two soil samples. The bulk of the embankment is the sandy-s'lty material, <br />which has an optimum moisture content of 7.8X and a maximum dry ensity of <br />133.5 pounds per cubic foot. The Eine soil, which was quite lim'ted in <br />extent, had an optimum moisture content of 19.4X and a maximum d y density of <br />109.5 pounds per cubic Foot. It is not anticipated that signifi ant amounts <br />of this clayey soil x111 be found on the project site. The SW-S soil is much <br />more representative of what is found on site, although a higher lay content <br />is typically found end reflected in the sample that was tested. <br />In-place testing of the compacted embankment materiel has reveal d values of <br />125 to 135 pounds per cubic foot and about 6X moisture content. This is 95X <br />to 100X of the standard Proctor density, which is in accordance 'th good <br />geotechnical construction. Although the embankment may utilize ome portions <br />of the historic berm as a foundation, the density found in the historic berm <br />was also in the vicinity of 135 pounds per cubic foot. This ind'cates the <br />resulting compacted embankment can be considered a well construc ed, reliable <br />structure. The embankment can be generally classified as a homo eneous <br />embankment rather than a zoned dam. For this classification it 's customary <br />for some seepage to appear in the downstream face of the dam dur'ng steady- <br />state high water level conditions. As long as no piping (washin of material <br />out of the dam) occurs, such seepage is a common, expected situa ion that does <br />not endanger the structure. <br />• ALbanknent Slope Design <br />As shown on Plate No. lA, the revised embankment is called Fort have a 3:1 <br />slope upstream and downstream, a 15 foot wide crest, and a maxim m height of <br />approximately 20 feet above the downstream toe of the embankment The <br />structural height of the dam will be significantly less since na ural ground <br />rises significantly and probably is on the order of 10 to 14 fee at the <br />center line of the embankment. The embankments were laid out ac ording to the <br />standardized slopes presented in the Bureau of Reclamation's Des n of Small <br />Dams, a standard reference text for small earth embankments. Th ee-to-one <br />slopes may actually be conservative, since 2.5 or 2:1 slopes wou d be within <br />those accepted guidelines. However, it was decided that conserv tism was <br />preferred. Since standard, commonly accepted embankment slopes re being used <br />in accordance with the onsite materials found at the Alma Placer project, a <br />stability analysis has not been performed. A stability analysis typically is <br />only performed when an attempt is made to optimize the embankmen and utilize <br />steeper slopes than those recommended by the guidelines noted ab ve. <br />• Pond Capacity <br />It is anticipated that the bottom of the ponds will be enlarged omewhat <br />upslope of the embankments. At this time, we estimate that the aximum depth <br />of storage water will be on the order of 8 feet, and the maximum surface area <br />will encompass an area 800 feet long by 200 Eeet wide. <br />2 <br />