Post-Earthquake Investigations

Port of Seattle

Seattle, Washington

Seattle waterfront

Photo: Don Wilson

In response to the Nisqually earthquake in 2001, Hart Crowser conducted a geotechnical inventory of earthquake-related damage for Port of Seattle waterfront facilities. This included most of the major Port of Seattle terminals to catalogue the extent of damage to piers and upland pavement systems. As a result we accumulated a library of information about the amount of ground surface subsidence that occurred within the port terminals from localized seismic liquefaction. Since we designed most of these systems, and this design included analyses to predict the amount of ground surface subsidence that would occur, we were able to “calibrate” these settlement estimate procedures to more realistically estimate potential subsidence of slabs-on-grade and pavements. Our work since has included design recommendations for cost effective repair of stormwater outfalls.

At Terminal 5, bathymetry data showed a mound of material in the bulkhead area, and there was concern that the sheet pile wall may have failed or the slope above may have failed. Hart Crowser worked in conjunction with the structural engineer to advise the diving team during the underwater investigation. The investigation determined that the wall had performed as intended and that the “mound” was due to a bathymetry data error.