Electrical Power for Valdez and the Copper River Basin-1981

3. Diesel - Pressure Reducing Turbine (PRT) (Plan B)The proposed PRT would be located 5 miles east of the oil pipelineterminal at a site on the Trans-Alaska pipeline, Block Valve No. 125,where the necessary tap was installed during construction. This area wasselected to take advantage of the head available as the pipeline descendsThompson Pass. The PRT would produce approximately 7.4 megawatts ofelectrical power based on a flow of 1.5 million barrels per day. Theadvantages of this plan are the relatively low installation costs and thelow environmental impacts. The disadvantages include the relativelyshort life of the pipeline project and the assurance of constant oilflows. The oil reserves in the Prudhoe Bay area may be depleted within15 to 20 years which would terminate the PRT project. Maintenance andemergency shutdown of the Trans-Alaska pipeline would cease electricalgeneration. During the periods of shutdown, a standby diesel generationsystem would be utilized. This system would have to be maintained yearroundto insure dependable power when the PRT is nonoperational. Onlyminor environmental impacts associated with disturbance and thetransmission corridor would occur with this plan.It should be noted that the Corps of Engineers has no authority toconstruct or fund either diesel generation or the pressure reducingturbine.4. Diesel - Hydroelectric (Plan C)The hydroelectric portion of this alternative will consist of a tap ofAllison Lake, power tunnel, above ground penstock, powerhouse, and atransmission line intertie with the Solomon Gulch substation. The hydroelectricgeneration will provide approximately 8 megawatts of installedcapacity to the Valdez-Glennallen area. The hydroelectric alternativewill require mitigative measures to sustain the salmon run in AllisonCreek. Sug- gested mitigation includes a two tailrace system to maintainwater quality and flow in Allison Creek, and a comprehensive biologicalmonitoring study to insure the quality of the fisheries resource ismaintained at preconstruct ion levels.The diesel portion of this alternative would be utilized to meet loadrequirements above the capabil ity of the hydroelectric project. Bothsystems would be necessary by the time Allison Creek comes on line. (SeeFigure 4 under the section "Comparison of Detailed Plans.")The hydroelectric portion of this alternative is under the Corps ofEngineers· authorization, and can be constructed or funded forconstruction under this authority.5. Pressure Reducing Turbine (PRT) - Hydroelectric (Plan D)The design of both portions of this alternative are identical to thosepreviously discussed.This alternative would utilize the PRT for the base load and hydroelectricfor peak load demand and back-up. The power generated from thisEI5-2