Terminal 5 Berth Deepening and Facility Modernization

Port of Seattle, Washington

Terminal 5

The Port of Seattle plans to reconfigure and modernize Terminal 5 to support ultra-large container ships carrying more than 18,000 20-foot equivalent unit containers (TEUs). The modernization includes wharf strengthening, berth deepening, upland improvements, and power upgrades.

Geotechnical Engineering

Hart Crowser provided geotechnical and seismic engineering services to support larger cranes and deepen the berthing capacity. Hart Crowser developed a unique test pile program designed to save more than a million dollars during construction.

The project was complicated by significant liquefaction hazard and slope stability issues, as well as prior infrastructure limitations. A new structural wall at the toe of the slope was designed to replace the function of the “toe wall” that was previously constructed. This wall will be 20 feet high in some places with a steep slope behind it. The project included a combination wall consisting of interlocking H-piles as well as ground stabilization, in the form of compaction piles behind the structural wall to further strengthen the toe of the slope.

Permitting and Environmental Services

Hart Crowser has also provided permitting, environmental, and engineering services related to wharf strengthening and dredging on the lower Duwamish River. We helped prepare the core Joint Aquatic Resource Permitting Application (JARPA) and SEPA Checklist for Sections 10/404/401 permits, Hydraulic Project Approval (HPA), Shoreline permits, and SEPA analysis. Hart Crowser prepared the Biological Assessment and led all Endangered Species Act Section 7 Consultation activities with the federal services. We performed extensive underwater noise analyses to determine the potential effects of driving over 3,000 piles to Endangered Species Act-listed salmonids, birds, and marine mammals.

We helped Port of Seattle engineers develop a unique pile-driving schedule with multiple pile-driving rigs to accommodate both construction schedules and agency-mandated waterborne noise restrictions. Hart Crowser prepared and implemented multiple monitoring plans (specifically for marine mammals and marbled murrelets) for the construction phase and implemented them while overseeing the test pile program. We also conducted sediment sampling and analysis following Dredged Material Management Program protocols.