DBM Contractors, Inc., with support from alliance partner Pennine, completed the design/build installation of the ground improvement at the $255-million Washington State Department of Information Services building on the Wheeler site in Olympia. Crews installed 2,200 stone columns to a depth of between 15 ft and 30 ft to improve the soils below the structural foundations and to increase the soil bearing capacity, reduce static settlement and reduce liquefaction risk in the liquefiable soils.

The three-building campus will serve as office and data center space for the state. The general contractor on the 394,000-sq-ft project is Howard S. Wright Constructors and the developer is Wright Runstad & Co.

The fast track ground improvement project required coordination with the excavation subcontractor and the foundation contractor and required work be completed within a confined deep excavation for the three building campus. Stone column ground improvement was selected as a suitable means to satisfy geotechnical and structural engineering requirements for the project, and with time and cost advantages over structural deep foundation alternatives.

FYI Properties, a non-profit entity formed by the National Development Council is the owner of the project. Other consultants on the project include: architect, NBBJ; ground improvement design partner, Lachel & Associates; structural engineer, KPFF; and geotechnical engineer, Haley and Aldrich.