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Alternatives Evaluated <br /> The alternative locations to obtain Vallecito Reservoir water are described in this section which <br /> include: (1) at the exit from the outlet tunnel, (2) at the discharge from the power plant about <br /> 1,000 feet below the dam, and (3) a diversion from the Pine River about 2 miles below the dam <br /> near Red Creek. The outlet works from Vallecito Dam consists of two outlet gates at the center <br /> of the dam which release water either into an outlet tunnel that conveys water to the spillway or <br /> into a pressurized lined tunnel that conveys water to a power plant about 1,000 feet below the <br /> dam (at the base of the spillway chute). The pressurized pipeline exits the tunnel at the toe of the <br /> dam where a buried 7 foot diameter steel pipe conveys water to the power plant roughly parallel <br /> to the spillway. <br /> An evaluation of the alternatives follows: <br /> (1) Divert at Outlet Tunnel: The diversion at the outlet tunnel involves a tap into the pipeline <br /> exiting the outlet tunnel, a 500 foot pipeline to convey water to the treatment plant, a bridge over <br /> the spillway chute would be necessary, and a pump when the reservoir water level is low or to <br /> pressurize the treatment plant. The location has the shortest pipeline and does not require a Corp <br /> of Engineer 404 Permit because there is no activity in the river channel. <br /> (2) Divert at the Power Plant - Obtain reservoir water by tapping into the penstock at the power <br /> plant, install a 1,500 pipeline to convey water to the treatment plant site at the same location as <br /> option (1). When pumping is necessary, the pump lift would be greater than (1) because of <br /> additional friction losses in longer pipelines. Occasionally the penstock is not operational due to <br /> repairs, so a temporary pump from the stilling basin pool below the spillway would be necessary. <br /> (3) Divert Near Red Creek - Diversion would be upstream of the confluence of Red Creek and <br /> Pine River. The treatment plant would be constructed on the west side of the river north of the <br /> gravel pit with the diversion upstream of Red Creek. The plant would be at about elevation <br /> 7,480 feet. The site is about 120 feet lower in elevation than options (1) and (2) requiring an <br /> additional pump lift. The diversion from river will be difficult because of steep channel bank, <br /> low flow, shallow channel and winter ice; probably need a gallery in bottom of channel which are <br /> costly and require backflushing periodically. A Corp of Engineers 404 Permit is necessary. <br /> Recommendation - Option (1) is recommended because it has the least impact on the river, there <br /> is the least pumping and the construction cost is least. <br /> The District's engineer provided technical engineering assistance in the evaluation of the above <br /> alternatives, particularly concerning the type and configuration of the facilities and river <br /> diversion problems. <br /> 4 <br />