The Port of Tacoma is preparing to berth some of the biggest ships in the world. Container ships are quickly outgrowing the U.S. ports that serve them – a trend that shows no sign of slowing down. These enormous container ships enable liners, shippers, and cargo owners to ship more goods at a lower unit cost. The newest of these ultra-large container ships carry more than 18,000 TEUs (20-foot equivalent unit containers), significantly exceeding Panamax dimensions (i.e., the largest ones that can pass through the Panama Canal, about 4,000 TEUs in 1985 and about 12,500 TEUs planned in 2015). These ultra-large container ships currently serve only the Asia-Europe trade routes, and exceed the capacity of U.S. ports. The average size ship calling on U.S. ports is still below 6,000 TEUs, but California ports have begun berthing 12,000 to 14,000 TEU ships. The increasing size of these ships puts pressure on ports to remodel, and fast, or else lose business to a competing port. Ports need to modify their channels and piers to accommodate these behemoths and upgrade their infrastructure to quickly unload, stage, and transport these containers to the hinterlands. See the trend in Vessel size over time in the graphic below.
Source: Sisson, M. (2013). “Impact and Opportunities from Global Change.” Presented at AAPA Facilities Engineering Seminar on November 6, 2013
The Port of Tacoma is redeveloping the Husky Terminal to allow the simultaneous berthing of two 18,000 TEU ultra-large container ships, which are about 1,300 feet long and 205 feet wide. This project involves the reconfiguration and construction of Pier 4 to align with Pier 3, creating a 2,954 feet long pier that can accommodate up to six 100-foot cranes capable of loading ships that are 24 containers wide. The project enables the Port of Tacoma to be one the first U.S. ports capable of berthing these ultra-large container ships, allowing the port to remain an economic engine for the Pacific Northwest.
Although a natural deep water port, this project involves the dredging of approximately 500,000 cubic yards of sediment, including about 45,000 cubic yards of tributyltin (TBT) contaminated sediment that will be dredged during Phase I of the project. TBT is a marine biocide that was commonly used in ship paint to kill mollusks, but is now globally banned. Aspect engineers Alan Noell and Tom Atkins worked with lead-engineering firm KPFF to evaluate TBT treatment technologies and to design a water treatment system capable of treating millions of gallons of TBT-contaminated dredge return water. Phase I of the project is currently underway with scheduled completion by April 2016, and soon after, the Port will move towards completing Phase II and begin berthing these ultra-large container ships.