Construction of a new International Arrivals Facility at Sea-Tac Airport is officially underway.

Contractors have already been busy removing a bus log to the east of Concourse A, which will become the largest piece of the new facility. It will also feature a large skybridge to the current south satellite where international passengers now arrive.

The main reason the airport will now spend $766 million to build the new facility is growth. Following three years as the fastest growing airport in the country, it's now the ninth largest airport in the country.

The current facility was built in the 1970's to process 1,200 passengers per hour. The airport is often pushed to 2,000 passengers per hour, and the new facility will process 2,600. The plan will also expand the number of gates available for international flights.

The new IAF is scheduled to open in the fourth quarter of 2019.

The multistory facility will be built east of the current concourse A and will handle U.S. Customs, immigration, and other functions. It will total 450,000 square feet. That overhead walkway will be 900 feet long.

How is it being paid for? According to the Port of Seattle, most of the money will come from the $4.50 passenger facility charge placed on tickets. Other revenues will come from port operations, but none if it from King County taxpayers.

The price tag just went up another $105.6 million. Much of it comes from having to compete for contractors and building materials in high demand for big construction projects in Seattle, Bellevue, and other places around the region. That, says the port, is the very reason the airport is growing like crazy.

The Port’s mission is economic growth for the region. Sea-Tac has added six new international airlines since the beginning of 2016, and says each carrier is worth nearly $90 million to the region’s economy. The Port also says international passengers per capita tend to stay longer and spend more money when they’re here.