October 2, 2023

Port of Seattle approves $400M expansion at Sea-Tac Airport

Renderings by The Miller Hull Partnership via Port of Seattle [enlarge]

The expansion’s exterior facade will be constructed with alternating south and west facing glass panels.

The Port of Seattle has officially approved a nearly $400 million project to expand and totally reimagine the C Concourse building at Seattle-Tacoma International Airport.

The port approved a total budget of $399 million for the project last Tuesday, meaning major construction work on the expansion can soon begin.

The expansion will increase the existing 81,000-square-foot C Concourse building to 226,530 square feet.

The plan is to add four new floors above the existing building. Those floors will span to D Concourse, significantly increase the hold room size of the current structure and will add a host of new amenities for patrons.

[enlarge]

Miller Hull describes the expansion as “an extension of the region,” with interiors inspired by the natural landscapes of the Pacific Northwest.

Amenities include around 145,500 square feet of restaurant and retail space, an interfaith prayer room, outdoor public lookout, a meditation room, nursing suite, and a new 20,000-square-foot Alaska Airlines Lounge. The expansion will also house new office space for airport businesses, airlines and the TSA.

Design work for the project kicked off in 2021 and early construction work (civil/foundational) began the following year. The Miller Hull Partnership is designing the expansion in partnership with Woods Bagot. It will be built by Turner Construction.

The port expects major construction work to start early next year and the expansion to be significantly completed and in use towards the end of 2026. Total completion is forecast for 2027.

Funding for the project comes from a combination of Airport Development Fund and future revenue bonds. No tax-payer dollars will be used to fund the project. At inception, the total project budget was estimated to be between $240 million and $500 million.

Image via Port of Seattle [enlarge]

The addition will add four floors atop the existing C Concourse building.

The expanded building is set to be a new marquee space at the airport. Its design is inspired by the natural landscapes of the Pacific Northwest, defined by biophilic elements that connect occupants to nature and will give the space a feeling of calm. These include a signature wooden ceiling.

Topped by that ceiling at the heart of the expansion will be a set of grand stairs that will double as an open-air amphitheater. The stairs will create a central gathering space designed to be reminiscent of regional public and farmers markets. Dining and retail will frame the tiered, open amphitheater which will also provide a stage for live music. At the top of the stairs will be an upper level with more restaurants.

The port says one of the most unique aspects of the C Concourse expansion is its height which will allow for unobstructed views of the airfield and Olympic Mountains via a glass-encased lookout deck.

The exterior of the expansion will be constructed with alternating south and west facing glass panels that will respond to the sun's position and intensity with dynamic tinting electrochromic glass to prevent interior glare and optimize daylight. Miller Hull says this folded facade will address challenging southwest-facing aperture.

The expansion project is targeting LEED v4 Silver certification. Sustainability initiatives include all electric/fossil-fuel free systems; a rooftop solar PV array; enhanced indoor air quality with high performance air delivery system; and the use of healthy building materials to reduce embodied carbon. Miller Hull says local materials will also be sourced for the project.

The project team for the expansion also includes; Magnusson Klemencic Associates, structural and civil engineer; PAE, mechanical, plumbing and sustainability engineers; ARUP, electrical engineer, smoke control, airfield and logistics; AirProjects, airport dining and retail consultant; Moye Consulting, IT, communications and security; Mayer Reed, wayfinding and signage; Dark|Light, lighting design; The Greenbusch Group, acoustics and vertical transportation; Hart Crowser, Geotechnical Engineer; Cumming, cost advice; Jensen Hughes, code compliance and fire protection; Code Unlimited, Inc., accessibility/ADA; Autoscan, BIM; and Holt Services, site investigations and surveying.