Seattle-Tacoma International Airport’s $1.5-billion South Concourse Evolution project is advancing toward construction with the selection of Hensel Phelps Construction Co. as the general contractor/construction manager.

The Port of Seattle sent Hensel Phelps a notice of intent to award last month, starting with a preconstruction contract, a company spokesperson says. The port estimates the value of the preconstruction at $8 million and the maximum allowable construction cost contract at $900 million, records show.

Last month, the port also brought on AECOM to lead design and engineering for the project, HOK as lead designer and Jacobs for project management services. The port estimates construction will start in 2025 and complete in 2031. 

The plan calls for improvements to the airport’s 350,000-sq-ft South Concourse, which was built in 1973 and last expanded in 1984. Renovations would update the facility to meet current building code requirements and add seismic support, according to the port. 

Unused space that formerly housed Federal Inspection Services and Customs and Border Protection would be redeveloped for passenger amenities. Also, the concourse level would be renovated to improve circulation and the penthouse level would be expanded for more lounge space. 

The work is needed to meet increased demand for international travel and to extend the concourse’s service life for another 50 years, according to the port. 

Port records show Hensel Phelps beat out a shortlist of finalists including Hoffman Skanska Joint Venture, PCL Construction Services Inc. and Turner Walsh Partners. Hensel Phelps’ proposal earned the highest scores in categories including past performance, quality assurance and local market knowledge, port records show. 

Hensel Phelps has previously worked on several projects at Sea-Tac airport, including the $494-million North Satellite Modernization project completed in 2021. It is also working on the North Main Terminal Redevelopment project at the airport for Alaska Airlines, which is scheduled for completion in 2026. 

The Port has set a 2% disadvantaged business enterprise participation goal. The work is subject to a project labor agreement.