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I I I I I I I I I I I I I I I I I I I will be on each downstream leg of the "T". The butterfly valves will be automatically operated. The bypass pipe will loop over the top of the turbine and will be used if the turbine is shut down. The automatic valves will direct water through the bypass. The bypass is included because releases must be made to downstream water users if the unit is inoperable. This configuration will provide the best turbine output because the head loss is the least. Also the pipe system is the shortest and has the fewest bends which will reduce the turbulence as much as possible. The cost of removing the concrete from the bend will be less than constructing the pedestal in Plan C but more than the extra piping in Plan B. The most significant advantage is that about 90,000 additional kWh per year will be generated with this plan over the other configurations. Piping Plan A is the best piping plan when considering the long term performance, and if it can be developed in conjunction with the outlet dewatering for the gate repair, would be the " recommended action. If for some reason the gate repair is de- layed, Plan B would be recommended. Then when the outlet is de- watered at a later time, Piping Plan A can then be incorporated without moving the turbine. 7.3 TURBINE SELECTION The turbine for Lemon Dam must meet four specific criteria: 1) the turbine and generator must physically fit in the space available in the gate chamber, 2) the turbine and generator must fit in the elevator or through the manhole in order to be moved to the gate chamber, 3) performance curves on the turbine operation must be available to evaluate the unit output and determine if the unit would maintain releases between 9 and 13 cfs, and 4) the revolutions per minute (rpm) of the unit must be about 1200 or less to avoid cavitation at the elevation setting. (See Appendix C.) 7.0-9