It's still not clear exactly what led to the deaths of two workers when the trench they were working in flooded, and whether the tragedy might have been preventable.

But some details are coming to light that raise questions about the company involved in the incident, Atlantic Drain Service Company, Inc. — and what is, and isn’t, being done to protect other workers exposed to similar risks.

An analysis of various data related to the permitting, inspection and issuance of safety violations for excavation and water and sewer line work like that being performed by the workers who died suggests that the volume of such work vastly outpaces efforts by federal and local government to inspect sites for worker safety.

And it's unclear to what extent citations issued for the relative few companies and work sites that are inspected are sufficient to change company behavior. 

Within the last five years, Atlantic Drain Service Company, Inc. was cited thirteen times for violations of worker safety rules byOSHA, the federal Occupational Safety and Health Administration, including for failure to provide emergency training, rescue crews and cave-in protection for workers in trenches. 

As WGBH News reported earlier this week, that was more than double the number of violations issued to any other company doing similar work in Massachusetts during that time. 

Despite those citations, and not paying tens of thousands of dollars in fines imposed by OSHA, the company was able to continue doing business.

That speaks to a larger problem says Marcy Goldstein-Geld of the watchdog group, the Massachusetts Coalition for Occupational Safety and Health.

“Imagine that you get a speeding ticket or even a parking ticket … your car would get booted after a few tickets. Here we have an employer that puts workers in life-threatening situations and they’re continuing to operate. There’s no boot on their business.”

OSHA data reviewed by WGBH News shows that dozens of other companies doing sewer and water line work in Massachusetts have also been cited for similar violations in recent years.

And most work sites never even get inspected. Since 2014, the City of Boston alone has issued more than 20,000 excavation permits. 

That's about five times the number of OSHA investigations of any business, of any kind, anywhere in the Commonwealth over the same period. 

A few days after the workers died, Mayor Marty Walsh conceded that there are limits to the city’s oversight.

"This was a private contractor doing work for a private development," Walsh told reporters during a press conference meant to highlight the city's efforts around early voting. "If they have a valid license, there's not a lot we can do."

The incident remains under investigation by OSHA and the Suffolk District Attorney’s office.