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I I I I I I I I I I I I I I I I I I I 2. Problem Areas and Proposed Improvements. The only problems that will require attention at Reservoir No. 6 are associated with the outlet. The outlet was partially repaired and upgraded In 1980 but stili retains some of the original masonry construction. Two options were studied for the repair of the outlet. One option Is to repair the outlet and the second Is to remove and replace the outlet. The two alternatives are outlined below. Alternative No.1 I. The remaining 90 feet of the original masonry conduit In the central portion of the dam will need to be relined to ensure problems do not Initiate along the outlet. 2. The gatehouse will require some repair due to Its masonry construc- tion and a new gate and operator will need to be added. 3. The outlet conduit will need to be extended with 100 feet of 36- Inch RCP, the dam flattened In the area of the outlet. and an outlet control and energy dissipation structure added. 4. The seepage problems at the outlet ditch will require the Installa- tion of 360 feet of toe drain at the dam toe and along the outlet conduit to control the phreatic surface at the dam toe. Figure V-8 shows the details of the existing outlet and Figure V-7 shows the proposed Improvements. The completion of these repairs should bring the dam Into compliance with the requirements of the State Engineer and allow removal of the hold order on the reservoir. Alternative No. 2 I. Breach the dam and remove the existing outlet conduit and gate- house. 2. Construct a new outlet worj(s with approximately 300 feet of 36-lnch precast reinforced concrete pipe, a new Intake structure, outlet structure and energy dlsslpator, and InclIned gate and operator. 3. Flatten the downstream slope to stabilize the outlet channel and protect the dam against the backwater from Reservoir NO.6. B.2. FURTHER INVESTIGATIONS. No geotechnical or other physical Investigations have been conducted or are planned to be conducted on the Reservoir No. 6 dam and site prior to final design. Since the dam was rehabilitated In 1980, stability analyses and other geotechnical analyses were not conducted. The focus of the work on No. 5 Is primarily to repair the outlet, Install toe drains, and flatten the downstream slope at the outlet. The dam has relatively flat slopes and would not be expected to experience any stability problems with the addition of the needed repairs noted above. The subsurface geologic conditions would be expected to be similar to that described In Section A.4. and A.5. of this chapter for Reservoir No. 6 and are typical of the geology In this drainage basin. The geology and conditions of Reservoir No.2, which Is In the same basin, are similar to that at No. 6 and PAGS 18 Cblpler V - No. 6 Veuiblllty