Electrical Power for Valdez and the Copper River Basin-1981

alternative has been estimated to provide sufficient energy to the studyarea until about 1995. When the power generated from the PRT terminates,an intertie with the Anchorage-Fairbanks area may be feasible.C. AFFECTED ENVIRONMENT1. Physicala. General: Two specific sites are possible for development; theLowe River flats and Allison Creek.The proposed PRT site lies at the head of Port Valdez on the south sideof Lowe River. The valley is of glacial origin and is filled with outwashaeposits of the Valdez and Corbin glaciers. The site is bounded onthe north by the Lowe River, and south by the Chugach Mountains.Allison Lake is located on the south side of Port Valdez, directly acrossfrom the present city of Valdez, filling approximately one half of aglacier formed hanging valley. Allison Creek, which originates atAllison Lake, decends 1,360 feet in 2-1/4 miles to Port Valdez. It is anextremely high graaient stream for the first 2 miles with the lastquarter mile leveling considerably.The area is underlain geologically by the late Cretaceous Valaez Group, aseries of metagraywackes, shales and slates with occasional beds ofpillow basalt. This is indicative of a rapid, unsorted deposition in anocean environment. The beds are highly disturbed and no regionalstructures have yet been defined.The Port Valdez area is located in Seismic Zone 4, approximately 46 mileseast of the epicenter of the 27 March 1964 earthquake. Prior to 1964,there were approximately 70 earthquakes, magnitude 5 or greater, in theValdez vicinity.Excluding the 1964 earthquake, magnitude 5 earthquakes have averagedapproximately one per year. Magnitude 8 or greater events have occurredthree times this century, consequently, there is a good probability of alarge earthquake occurring during the life of the project.There has been no evidence of ruptures in area bedrock. Most destructionin port Valdez has been causea by tsunami and submarine mass movement ofunconsolidated Lower River delta deposits.The site for the proposed powerhouse (Alternate #2) is located at the 100foot elevation. Powerhouse Alternate #1, located on delta deposits atthe 20 foot elevation has been dismissed from further consideration. Thedelta deposits would make good foundation material for a small surfacepowerplant; however, the area may be subject to tsunami to an elevationof +85 MLLW. During slide induced sea waves, runup at Anderson Bay, 7miles west of Allison Creek, was measured at 70 feet. Measurements atShoup Bay (Cliff Marine) on the north side of the arm show a runup of 170feet. No runup measurements were made at Jackson Point or Fort Liscum,but the cannery at Jackson Point was destroyed.EIS-3