When it comes to the timely reporting of gas accidents to federal safety authorities, Columbia Gas of Massachusetts, the company operating the gas lines involved in the recent Merrimack Valley explosions, and other subsidiaries of its parent company have a history of delays and noncompliance with federal reporting requirements.

Federal safety data analyzed by WGBH News shows Columbia Gas of Massachusetts had been late in reporting serious hazmat incidents to federal authorities prior to the series of explosions that displaced thousands of Merrimack Valley residents and killed one man.

And a review of gas accidents since 2010 involving more than 170 gas companies nationwide shows that Columbia Gas of Massachusetts and other subsidiaries of its parent company, NiSource, have together reported at least 15 gas explosions since 2010 — not including the three explosions that caused fires in Lawrence, Andover and North Andover last week.

The same data show that some of those other subsidiaries have also taken significantly longer to report those accidents to federal authorities than the vast majority of other gas companies for which there is reliable data.

According to data maintained by the federal Pipeline and Hazardous Materials Safety Administration (PHMSA), Columbia Gas of Massachusetts has reported 11 hazardous materials incidents since 2010 before last week’s blasts, including at least two explosions — more than any other gas company operating in Massachusetts during that time.

Boston Gas Company reported eight incidents over the same period. Colonial Gas of Lowell and NStar, which is now Eversource, each reported three.

But in some cases, Columbia Gas of Massachusetts, failed to report those incidents within guidelines.

The Massachusetts Department of Public Utilities, which oversees local gas companies, was unable at this time to comment.

U.S. government requirements

Federal guidelines require that any emergency spill, leak or other hazardous release be reported to the National Response Center (NRC) hotline “at the earliest practicable moment following discovery, but no later than one hour after confirmed discovery” of any gas release that results in death, serious injury, or significant property damage. In less severe cases, operators are expected to report to the NRC as soon as possible but within 12 hours.

The requirement exists even if gas operators contact local emergency responders, because it allows federal authorities to respond if or as necessary in the case of potentially catastrophic emergencies.

The recent explosions in the Merrimack Valley appear to have been reported within that timeframe.

NRC records show receiving emergency calls beginning about 4:30 pm, indicating that the state’s Department of Public Utilities and the local fire departments had been contacted. The data does not specify whether the caller was Columbia Gas of Massachusetts.

A spokesperson for the Columbia Gas said he was unable to immediately comment.

A spokesperson for the Massachusetts Emergency Management Agency, MEMA, also said he was unable to comment on the response due to an ongoing investigation by the National Safety Transportation Board.

A history of poor reporting performance

According to federal records, Columbia Gas of Massachusetts took days, weeks and even months to report several prior incidents, including ones involving explosions and ignitions of gas.

PHMSA defines an “explosion” as “the ignition of released gas … with a sudden and violent release of energy.”

In 2012, when a rolled-over truck caused a gas line to ignite and burn a restaurant in Seekonk, Massachusetts, it took Columbia Gas just over five days to report the incident to the National Response Center.

In 2015, the company failed to report three explosions, all within a few weeks of each other, to the NRC for an average fifty days per incident.

The company acknowledged the delays in separate reports for each of those three incidents to the PHMSA.

“There was a breakdown in the notification process which resulted in a delayed NRC call being made,” those reports state. “The company has since implemented annual training to provide continuous education on the reporting requirements at both a state and federal level.”

But those three reports, required by PHMSA to be submitted within 30 days, were also late. The first was submitted 79 days late; the second 28 days late; and the third 47 days late.

The bigger picture

In a letter issued Monday by Massachusetts Senators Elizabeth Warren and Ed Markey, the senators raised various questions about how the explosions occurred and how Columbia Gas of Massachusetts in particular handled response. Among those questions: whether the company reported the incident to the NRC within one hour as required.

Further data reviewed by WGBH News shows similar patterns for other subsidiaries of Columbia Gas’ parent company, NiSource, around the country.

In data from hazmat reports by more than 170 gas companies around the United States, the median time it took companies to report incidents to the National Response Center was about 6 hours — well within the twelve-hour deadline.

Among the longest average response times was not only Columbia Gas of Massachusetts, with an average of 533 hours, but also, Columbia Gas of Ohio, which took an average 490 hours.

Of 177 gas companies for which WGBH News had useable data, only two — Kansas Gas Company and Pudget Sound Energy — took longer, on average, to report to the NRC.

And while Columbia Gas of Massachusetts had reported three prior explosions since 2010 (only one ostensibly caused by error on the part of a Columbia Gas employee), its sister companies have also reported explosions, including seven linked to Columbia Gas of Ohio and one each for Columbia Gas of Pennsylvania, Kentucky, and Virginia, and two explosions linked to Northern Indiana Public Service Company, another NiSource-owned gas provider.

NiSource did not return requests for comment.

Michael Burg, an attorney who has represented victims in gas accidents — and who is currently taking on as clients victims of the Merrimack Valley — says the federal reporting requirements are no small matter.

“It puts everybody on notice that there’s a problem here, and that problem needs to be rectified right away,” Burg says. “And waiting two weeks, three weeks, it does not allow the government to get involved right away.”