Port of Tacoma – Maritime Center
The Port of Tacoma development includes construction of a new Skills Learning Center and Administrative Business Center adjacent to Tacoma Harbor. Both structures are supported on spread footings bearing on ground improved soils designed to meet project geotechnical performance requirements. To achieve these properties, Malcolm Drilling installed stone column ground improvement to increase bearing capacity and mitigate risks associated with settlement, liquefaction, and lateral spreading.
The stone column system, designed by GeoEngineers, extends beneath the full footprint of both structures, with higher column density provided beneath spread footing locations to meet performance criteria. A total of 1,435 stone columns were installed, including 601 columns beneath the Skills Learning Center and 834 columns beneath the Administrative Building. Each column measures approximately 30 inches in diameter and extends to an average depth of 30 feet, terminating in dense native soils.
Installation required adaptive field execution due to subsurface obstructions that necessitated localized layout adjustments. Malcolm Drilling worked collaboratively with GeoEngineers and the project team to successfully complete installation while maintaining design intent and performance requirements.
Post-installation verification included two modulus load tests (one per structure) and four post-improvement Cone Penetration Tests (CPTs), confirming that the ground improvement system achieved the specified design criteria.
