Boston Mayor Marty Walsh says his hands are tied when it comes to preventing future accidents like the water break that killed two construction workers in the South End earlier this month.

The drain service at the center of the accident, Atlantic Drain Service Company of Roslindale, had a long history of serious safety violations, according to reporting from the Boston Globe.But there's not much the mayor's office is legally able to do to discourage people from using licensed contractors, even when they have safety violations, Walsh told Boston Public Radio.

"We really don't have the legal ability to hold permits up on any contractor that has safety violations," Walsh said on Boston Public Radio Friday. 

"I can't tell a private citizen that 'you can't hire x contractor because x contractor has violations," he said.

The two workers were killed when a construction trench flooded with water and debris after a water line broke. 

Walsh said he was working with his office to see if any additional action could be taken on the city-level against companies with track records like Atlantic Drain.

"We can work to keep them off the bid list for the city contracts and work with city money on these projects," Walsh said. "This company that was involved in this incident last Friday is not on any city jobs."

Walsh's administration has recently been under fire for permitting issues of another kind. Tourism official Kenneth Brissette and intergovernmental relations officer Timothy Sullivan were indicted by federal authorities earlier this year for allegedly withholding city permits for the Boston Calling music festival until organizers hired unionized labor.

To hear more from Mayor Marty Walsh, tune in to Boston Public Radio above.