SR 525 Mukilteo Multimodal Ferry Terminal

Washington State Ferries, Washington State Department of Transportation & KPFF Consulting Engineers

Mukilteo, Washington

SR525 Mukilteo Multimodal Ferry Terminal

New Ferry Terminal Designed for Sustainability

Washington State Ferries (WSF)/Washington State Department of Transportation (WSDOT) built a completely new ferry terminal in Mukilteo, designed to LEED gold standards, at a site formerly occupied by a bulk fuel handling facility. Hart Crowser, a division of Haley & Aldrich, worked with WSF/WSDOT staff, KPFF Engineering Consultants and Jacobs to develop the geotechnical engineering design related to the various components of the new terminal. The project included nearly 200 piles for slope improvement, most of them in-water, and about 50 piles for the passenger terminal building foundation.

Upland and offshore facilities included the terminal building, ancillary buildings, parking areas, filled embankments and retaining walls over soft compressible soils, transfer spans, loading ramps, pedestrian ramps, mooring and breasting dolphins, and wing walls. The site is susceptible to seismic liquefaction and resultant lateral spreading.

Alternative Approach

Hart Crowser provided seismic design recommendations and recommendations for optimized improvements to mitigate the potential for excessive slope movement due to liquefaction-induced lateral spreading. The original permit documents called for extensive use of stone-column ground improvement. We helped develop an alternative approach that eliminated the need for most of the stone columns, by working with the structural engineer to design the new terminal building foundation system on the slope that would resist the lateral spread.