Columbia Gas of Massachusetts and its parent company NiSource are under a criminal investigation over the natural gas explosions that triggered a series of explosions and fires across three communities Sept. 13, killing one person and injuring about two dozen others.
NiSource disclosed the criminal investigation in regulatory filings, saying a federal grand jury served it and Columbia Gas subpoenas on Sept. 24, Reuters reported. The utility companies say they are cooperating with the ongoing probe, which the U.S. Attorney’s Office in Massachusetts is conducting. The grand jury is looking for evidence that Columbia Gas acted with neglect or other misconduct in causing and responding to the gas explosions.
The National Transportation Safety Board (NTSB), which is also investigating the explosions, said in a preliminary report last month that the explosions stemmed from faulty work orders given to crews replacing a century-old cast iron gas main with a plastic pipeline.
The work orders failed to instruct crews to deactivate pressure sensors where segments of the pipeline were removed, prompting the system to detect the drop in pressure. Because the system is built to automatically meet demand, it began injecting high volumes of gas into the pipelines, causing a buildup of pressure 12 times higher than the pipeline system could handle.
The excessive pressure destroyed and damaged hundreds of structures in the towns of Lawrence, Andover, and North Andover. Making matters worse, Columbia Gas did not shut off critical valves until nearly three-and-a-half hours after the first alarm was raised.
Columbia Gas’s response to the disaster was condemned by local and state officials as sloppy and incompetent. NiSource and Columbia Gas continue to repair the infrastructure affected by the explosions, but it may be mid-December before all affected customers have service restored.