The U.S. Army Corps of Engineers awarded the $45 million Dalles Dam Bay 8 and 9 Spillwall project to General Construction Company, a Kiewit Corporation subsidiary, to construct a spillwall in the stilling basin between Bays 8 and 9 at the Dalles Dam Spillway on the Columbia River.
The scope of work includes site work and building a temporary concrete precasting facility. The team is precasting concrete cells, the main components of the spillwall, at the facility and transporting them to the site via barge. The cells are set on the stilling basin slab and connected together by a lower-level tremie concrete placement and a conventional connector slab that is above water. Tendon anchors will be installed on the slab, and the cells are to be placed over the existing rock basin. Once this is complete, the team will remove the north temporary fish-ladder bridge and approaches. They will then remove a baffle block, located 25 feet underwater, and repair a tilted stilling basin slab.
The team is working hard to develop and use construction methods and a schedule to ensure compliance with environmental permits.