Electrical Power for Valdez and the Copper River Basin-1981

Power Tunne 1The power tunnel would be partially concrete lined 6-foot circularand oartially unlined 8-foot horseshoe shaped tunnel approximately 10,200feet lonq, from the lake tap chamber to the tunnel portal. About 100feet downstream of the gate structure, the power tunnel would drop at a45-deqree angle to elevation 1,050 and would continue down at 0.5 percentslope until it would daylight at elevation 1,000 at the tunnel portal.ApproximatAly 300 feet from the tunnel portal, a transition from a powertunnel to a steel penstock would occur.Intake TrashrackThe power tunnel entrance would be covered by a steel trashrack toprevent debris from entering the intake and reaching the turbines. Thetrashrack would be placed partially in the wet after the lake is drawndown through the power tunnel and aboveground penstock during the lowinflmv period.Gate Control RoomThe gate control room would consist of a hoist machinery room, avertical access shaft and a gate room. The hoist machinery room, locatedat elevation 1,456, would house a crane rail hoist and an elevator. Thevertical access shaft, which is approximately 200 feet long and 16 feethigh by 16 feet wide. would have a ladder from the hoist room to the gateroom. The elevator shaft would be adjacent to the access shaft and theelevator would be an overhead hoist cable operated system. The gate roomwould contain two 6 by 16 feet slide gates, one heavy duty and onestandard type, set in tandem. There would be a crane rail hoist at thegate room above the heavy gate for lifting and shifting the gate to thearea below the upper hoist during maintenance. An access hatch and avent would be provided at the gate room floor. The 18-inch diameter ventpipe would run from the power tunnel to the gate room and up through thevertical access shaft, to the hoist machinery room then finally outthrough the access adit.Access AditAccess to the gate control room would be through the access adit.The adit would be an 8-foot diameter horseshoe shaped tunnel, approximately100 feet in length and located at elevation 1,456. A 100- by100-foot staging area and heliport would be cleared adjacent to theaccess adit portal.PenstockThe penstock would be a 48-inch diameter, all welded structuresupported on concrete piers at approximately 40 feet on centers. Thesteel penstock would emerge from the power tunnel portal and wouldcontinue downstream to the aboveground powerhouse following the existingground contours. At alternate powerhouse Site No.1, the penstock wouldbifurcate into two penstocks immediately upstream of the powerhouse valveroom. Each penstock would connect with a valve in the valve room, anddownstream of each valve, a penstock extension would connect to a0-2