Photo: Scott Eisen Getty

Last week, a series of gas explosions rocked several communities north of Boston, starting at least 60 fires, killing one 18-year-old man, and leaving several injured. The National Transportation Safety Board now says the explosions and fires were caused by too much pressure in the pipes, which are owned by Columbia Gas, according to the Wall Street Journal.

From the Journal:

The NTSB, which investigates major pipeline accidents as well as transportation incidents, believes that gas flowed into homes at “significantly greater” rates and pressure than it was supposed to, Mr. Sumwalt said. “The real question for this investigation is to answer why this occurred,” he said.

Columbia Gas, the local utility, was in the process of replacing cast iron pipes with plastic pipes. NTSB is now investigating whether their construction played a role.

There are a few ways this could have happened, according to the Journal.

[Robert] Sumwalt [NTSB chairman] said there were indications that Columbia Gas was checking pressure on a different line and didn’t understand what was happening on the line that became overpressurized. He said the NTSB will examine “what effect, if any, did this have on the overpressure situation.”

Advertisement

Joe Hamrock, the CEO of NiSource, the parent company of Columbia Gas, told a press conference on Sunday that the company was fully cooperating with the investigation. The company is “committed to full transparency and collaboration to get to all of the underlying causes,” he said.

“It’s heartbreaking to see this devastation and this tragedy,” Hamrock added.

On Sunday, thousands of evacuated residents were given approval to return home. The Massachusetts Emergency Management Agency recommended that residents “be vigilant” for any signs of further gas leaks.

Advertisement

The NTSB report will take one or two years to complete, according to Sumwalt. But the agency may give recommendations for safety precautions sooner, if it discovers problems that may have contributed to the disaster.

“We want to find out what happened so that other communities don’t have to go through the devastation that has occurred right here in this area,” Sumwalt said.