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<br />u <br /> <br />. <br /> <br />that about one cfs was leaking through cracks in the concrete wall <br /> <br /> <br />adjacent to the north gate. The upstream half of the outlet works <br /> <br /> <br />tunnel is submerged and its condition is unknown. The downstream <br /> <br /> <br />half is in good condition, with a minor amount of leakage occurring <br /> <br /> <br />through a rock joint located about 50 feet downstream of the gates. <br /> <br /> <br />The dam caretaker has not observed any change in the outlet works <br /> <br /> <br />leakage during the last ten years. The poor condition of the con- <br /> <br /> <br />crete wall adjacent to the north gate and the high rate of leakage <br /> <br /> <br />through the gates warrant repair of the outlet works as a part of <br /> <br /> <br />the dam rehabilitation project. Repairs to the outlet works would <br /> <br /> <br />simplify construction of the tunnel extension and allow additional \ <br /> <br /> <br />water to be stored in the reservoir at times when the gates are~ <br /> <br /> <br />closed. <br /> <br /> <br />The reservoir should be empty during the outlet works repair. <br /> <br />. <br /> <br />The work could be more easily done during October and November while <br />the river is relatively low and weather conditions have not yet <br />become severe. Reservoir inflow during October and November averages <br />about 60 cfs and 45 cfs, respectively, but can vary widely from year <br />to year. Care of water would include construction of a small coffer- <br />dam, about 20 feet high, at the outlet works intake. An outlet pipe \ <br />or pipes would be placed in the cofferdam to allow release of water \ <br />through the outlet works at night. As an alternative to construction <br />of a cofferdam, it may be possible to divert the outlet works dis- I <br />, <br />charge through two open gates while the third gate is being repaired. i <br />Only when the outlet works gates are opened for inspection, will I~ <br />it be possible to determine exactly how the repairs should be made i <br />on the gate seals. Deteriorated concrete near the north gate should I <br />be chipped out and replaced with new reinforced concrete. Cavitation I <br />damage to the two concrete plugs located downstream of the gates need <br />not be repaired, since the concrete serves no structural purpose. <br />The cost and time required for repairs cannot be accurately <br /> <br />estimated until <br />cofferdam is in <br />that the outlet <br /> <br />the gates and upstream tunnel are inspected when the <br />place. On a very preliminary basis it is estimated <br />works repairs could be completed in one month unless <br /> <br />I <br />I~ <br /> <br />I <br />I <br />I <br />: <br /> <br />. <br /> <br />1 <br /> <br />-42- <br />