Deadly gas explosions blamed on over-pressurized lines
BOSTON — Over-pressurized natural gas lines were the source of deadly explosions and fires that rocked communities north of Boston last month, the National Transportation Safety Board said Thursday.
The five-page, preliminary report found that utility workers contracted by Columbia Gas had failed to account for critical pressure sensors as they replaced century-old castiron pipes in Lawrence on Sept. 13.
That omission caused high-pressure gas to flood the neighborhood’s distribution system at excessive levels, triggering more than 80 explosions and fires across the city, as well as neighboring Andover and North Andover.
One person was killed and about 25 others were injured in the ensuing chaos. The gas explosions also damaged 131 structures and destroyed five homes. Thousands of homes and businesses are still without natural gas service as Columbia Gas replaces some 50 miles of gas pipeline.
The work is about onethird complete, and the company says all customers should have gas service by Nov. 19.
Joe Hamrock, president of NiSource, Columbia Gas’ parent company, said in a statement that it is prohibited from comment or speculating on the cause of the incident until the federal investigation is complete.
But he noted that in the hours immediately after the incident, the utility company suspended similar work elsewhere and improved its procedures around low-pressure gas systems like the one in Lawrence.
“We saw these as responsible steps to take in the aftermath of the incident and while the facts were being gathered,” Hamrock said.
The National Transportation Safety Board, in its report, says the disaster was rooted in failures at the planning stages of the Lawrence pipeline project, which was developed and approved by Columbia Gas.