SEATTLE – Workers at Seattle-Tacoma International Airport filed more than a dozen class-action lawsuits Wednesday, saying they have not been paid a $15 minimum wage.

Their Seattle lawyers estimate the employees are owed as much as $20,000 each in back pay since the higher wage went into effect more than two years ago. They say about 5,000 airport workers are affected by the minimum wage ordinance, which now requires an hourly wage of at least $15.24.

An estimated 1,500 workers have not been paid the correct wage, the attorneys said. Calls to several of the employers targeted by the lawsuits were not immediately returned Wednesday.

SeaTac was the first city in the nation to adopt a $15 minimum wage, but it only applies to transportation and hospitality workers. It was soon followed by measures in Seattle and San Francisco that apply to all workers, but both of those cities are phasing in the higher wages.

Airport employers have fought the wage in court, saying the facility run by the Port of Seattle is a federal port that is not subject to local laws. The courts have disagreed.

These employees work a variety of jobs at the airport, from baggage handlers to the people who clean the planes and refuel them, said Duncan Turner of the Seattle law firm Badgley Mullins Turner.

Some have been offered settlements that represent a fraction of the back pay they are owed, Turner said. He estimates the total owed in back wages, plus overtime, related benefits and potential penalties could add up to $62.5 million.

“We want to see justice for all of the workers,” Turner said.

Three Seattle law firms are working together on the class-action lawsuits.