The terms of the settlement, including the amount of money involved, were not revealed. But lawyer David J. Marshall called the out-of-court settlement a "big victory for federal workers."
The 10 steamfitters "complained about hazardous working conditions at an agency of the U.S. Congress, stood strong for over a year in pursuing their complaints and achieved a great outcome," Marshall said.
A message left for an Architect of the Capitol spokeswoman was not immediately returned.
The 10 workers were responsible for maintaining the plumbing that provides steam and chilled water to Congress, the Library of Congress, the Supreme Court and other federal buildings and they work for the Architect of the Capitol.
The majority of the workers have retired, resigned or have moved to other assignments.
The workers complained publicly last year that the asbestos levels in the tunnels under the Capitol were unacceptably high and were affecting the health of workers. After they complained, the workers alleged that the architect's office retaliated against them.
According to the complaint filed with the Congressional Office of Compliance, the Tunnel Shop workers said the architect's office retaliated against them by describing them as troublemakers to members of Congress, threatening their jobs and cutting off supplies they need to work in an environment where the temperature can exceed 130 degrees.
The Office of Compliance oversees the civil rights and employment laws affecting congressional workers.
The settlement covers only the whistleblowers' complaints. The workers intend to ask Congress to compensate them for any asbestos injury and for medical monitoring for themselves and their families, Marshall said.