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<br />. \ <br /> <br />, <br /> <br />e( <br /> <br />. <br /> <br />-2- <br /> <br />Field Investigation <br />Our engineering geologist performed a limited reconnaissance <br />of , the reservoir and dam site area to verify the geologic conditions <br /> <br />I <br />I <br /> <br />displayed on the Geologic Map of the Morrison Quandrangle*. A portion <br /> <br /> <br />of that map in the vicinity of the planned reservoir is displayed on <br /> <br /> <br />Fig. 2 and explained by the descriptions on Fig. 3, <br /> <br /> <br />The boring was drilled from the shoulder of the Old Morrison Road <br /> <br /> <br />on the dam axis near the north abutment with a 4-inch diameter truck- <br /> <br />mounted continuous flight power auger to a depth of 29 feet. Our <br />engineer logged the materials encountered in the boring and obtained <br />samples of the materials for visual identification. A log of the boring <br />is presented on Fig. 4. <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Soil Conditions <br /> <br />Subsurface conditions encountered in the boring consist of 7 feet <br /> <br />of clayey fill underlain by natural 'sandy silt to 11 feet. The silt <br />is underlain by dense gravels and cobbles which extended to depth 19 <br />feet below which is interlayered sandstone and siltstone bedrock. <br />Ground water was encountered at depth 14 feet at the time of drilling, <br />The gravel and cobble layer caved into the hole during drilling and pre- <br />vented sampling of the bedrock. <br /> <br />Geology ~ Reservoir Area <br /> <br /> <br />The geology in the reservoir area is represented by the USGS <br /> <br /> <br />Geologic Map of the Morrison Quandrangle, a portion of which is printed <br /> <br />*Geologic Map of the Morrison Quandrangle by Glenn R. Scott, 1972, <br />United States Geological Survey (USGS) Map 1-790-A <br /> <br />.- <br />