Crews are preparing to break ground on a multi-million dollar project that will add more than 180,000 square feet to the aging North Satellite terminal at Sea-Tac Airport.

Related: Paine Field one step closer to having commercial flights

According to the Port of Seattle, U.S. Senator Maria Cantwell will join Port of Seattle Commissioner Stephanie Bowman along with Alaska Airlines and local labor representatives for an official ground breaking on Friday, Feb. 3.

Plans for the 45-year-old North Satellite Sea-Tac terminal call for an increased number of gates, from 12 to 20, which adds about 181,000 square feet to the facility and more than doubles the existing dining and retail square footage — from 19,000 to 46,000.

An upper-level mezzanine that will include full-service dining will be added.

The Sea-Tac terminal will be used exclusively by Alaska Airlines. The project is set to be completed by the spring of 2021.

The estimated cost for the port’s portion of the renovation is $549.9 million. Alaska Airlines will contribute an estimated $36.8 million to build a new board room and employee spaces.

The North Satellite redesign was approved by port commissioners in September.