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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 />f <br />I <br />I <br />I <br />I <br /> <br />conduit, and below a major seepage area on the face. Weir 4 is positioned <br />near the downstream toe, above and slightly to the right of the outlet works <br />structure. <br /> <br />The data collected provides interesting and valuable information regarding the <br />seepage behavior at the dam. During the above time period, flow through weir <br />1 never occurred. In early June, 1984, as the reservoir began to fill; all <br />wei rs were dry. As the reservoi r water surface rose through e1 evatl on 9498 <br />(G.H. 20), Weirs 2 and 3 began to flow. As the reservoir continued to rise <br />above el evati on 9501 (G. H. 23), wei I' 4 began to flow. The reservoi r water <br />surface peaked at elevation 9505 (G.H. 27) on June 20, 1984. Weirs 2, 3; and <br />4 were flowing at a maximum combined rate of 2.7 gpm. Within the next three <br />days, the reservoir was lowered to elevation 9501 (G.H. 23) and weir 4 ceased <br />fl owi ng. In the next two days, the reservoi r was lowered to the restri cted <br />level of elevation 9498 (G.H. 20), and weir 2 stopped flowing; For the <br />remainder of the time period, weir 3 flowed off and on as the reservoir water <br />surface fluctuated around the restricted level. <br /> <br />The seepage behavior described above clearly demonstrates two major sources of <br />seepage. The fact that weir 3 begins to flow when the reservoir is near the <br />restricted elevation of 9498 (G.H. 20), suggests that possibly a direct <br />hydraulic connection exists along the outlet works conduit through the dam. <br />The other major source of seepage appears to be along the right abutment - <br />embankment contact. Thi s seep is evi dent when the reservoi r water surface <br />occasionally exceeds the restricted elevation, when inflow is greater than the <br />outlet works capacity. <br /> <br />An approximate seepage analysis of the embankment was performed using <br />laboratory permeability results and the high-level steady-state phreatic <br />surface shown on Figure V.3. A seepage estimate of roughly 0.3 gpm was <br />obtained using an average permeabi1 ity of 2 x 10-5 cm/sec. (20 ft/yr) for <br />the dam. Thi s represents approximately 10 percent of the total measured <br />seepage when the reservoir was at elevation 9505 (G.H. 27l. Based on the <br />layered nature of the embankment revealed by exploratory borings; the <br />permeability of materials comprising the dam could span many orders of <br /> <br />-56- <br />