Port of Tacoma Pier 4 reconfiguration

Port of Tacoma/KPFF Consulting Engineers

Tacoma, Washington

Port of Tacoma Pier 4 Cranes

Photo: Northwest Seaport Alliance

The American Council of Engineering Companies of Washington awarded Hart Crowser a 2019 Silver Best in State Award for complexity for this project.

Local ports must evolve to meet industry needs, or ships and jobs will simply go elsewhere. The international marine cargo industry is rapidly changing—competition is intensifying, shipping lines are consolidating, and more mega ships are crossing the Pacific Ocean. For the Port of Tacoma and the Northwest Seaport Alliance, an important part of surmounting the competition is being able to handle some of the largest shipping vessels in the world, but the Port of Tacoma’s General Central Peninsula couldn’t accommodate such vessels. Pier 4 had to be completely reconfigured and aligned with Pier 3 to create a single 3,000-foot-long berth.

Hart Crowser supported multi-discipline engineering firm KPFF Consulting Engineers on this project, which involved demolishing the existing wharf, dredging enough sediment to fill a football field 215 feet high, constructing a new concrete wharf and marine operations building, and improving utilities throughout the site. All this while work continued while maintaining an active working terminal.

This was the first port in the Pacific Northwest to use a brand-new seismic code for wharfs and piers. And this was the first container terminal in the United States to use seismic isolators (which help prevent or minimize damage to a structure from an earthquake); this technology is typically only found in buildings and required unique analysis.

This project was especially complex because it didn’t just involve building a completely new pier. The team added and subtracted sections to straighten the zig-zag alignment of two piers into 3,000 feet of continuous berth. This created challenges that were successfully overcome:

  • The new structure was connected to the old structures. Each would react differently in an earthquake and damage each other, so the seismic design was carefully aligned.
  • The older piers had smaller piles with lower capacity and different seismic issues than the piles for the newer structure. That meant the newer, stronger piles would take some of the load that would have gone to the older, softer piles. The engineers accounted for this and made sure the new piles were capable of taking on this extra load, so the new design was compatible with the existing structure.
  • Dredging was done with great care so as not to damage or undermine the existing dock.

Even while the construction went on, operations continued at this very busy terminal. This meant the team had a smaller amount of space to work in. It also meant soil explorations had to be well-coordinated to make sure shipping containers wouldn’t be stored in the drilling locations and that a ship would not be actively unloading during drilling.

Bigger ships require bigger cranes. Bigger cranes are heavier and reach farther. That made the design of the piles—which support the heavier cranes—particularly important. And there were over 1,250 piles.

The reconfigured dock now supports the largest container cranes on the West Coast and can accommodate Ultra-Large Container Ships, which are some of the largest container vessels in the world. These new ships use 35 percent less fuel per box than smaller vessels and produce around 50 percent less carbon emissions.

The Pier 4 Phase 2 Reconfiguration was one of the largest single construction contracts issued in the Port of Tacoma’s history. Hart Crowser was honored to be a part of the new world class marine cargo facility that will serve the Port of Tacoma, the Northwest Seaport Alliance, and the community for many years to come.