The world's first floating prestressed concrete container dock, now in Valdez, Alaska, went into service late in 1982, less than a year after its keel was laid at Tacoma, Washington. The 700-foot-long dock was designed to provide year-round 24-hour-a-day cargo service to ships with up to 50,000-long-ton-capacity and barges up to 1500 tons. This type of concrete facility provides a high capacity marine terminal which requires only low maintenance, can be rapidly deployed, is suitable for deep water and poor soil conditions, is automatically self-adjusting to even the largest tide variations, and may be moved to another site should market conditions warrant it.
Each of the two pontoon-like units consists of 16 watertight compartments, the walls of which are made of full-height precast concrete pieces weighing 45 to 55 tons each. The bottom slab of each compartment and the vertical joints between the wall pieces are cast-in-place. A total of 468 prestressed concrete deck panels span the 25-foot-wide compartments. These panels serve as formwork for the final 12-inch-thick cast-in-place concrete deck.
This first-of-a-kind project not only broke new ground but also set an example for successful new applications of existing technology. Distinguishing elements of the Valdez Dock project included: Innovative use of a combination of precast and cast-in-place concrete that simultaneously maximized economy, speed of construction and product quality; extension of precast concrete technology to an important new field; and extensive cooperation between the owner, precaster, general contractor and engineer to maintain a tight 10-month schedule.