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Board Meeting: Overpressurization of Natural Gas Distribution System, Explosions, and Fires, in Merrimack Valley, Massachusetts, September 13, 2018 - Opening Statement
Robert L. Sumwalt
NTSB Boardroom and Conference Center

​Good morning, and welcome to the Boardroom of the National Transportation Safety Board.

I am Robert Sumwalt, and I’m honored to serve as the Chairman of the NTSB. Joining us are my colleagues on the Board, Vice Chairman Bruce Landsberg and Member Jennifer Homendy.

Today, we meet in open session, as required by the Government in the Sunshine Act, to consider the overpressure of the natural gas distribution system that led to explosions and fires in Merrimack Valley, Massachusetts, a little over a year ago, on September 13, 2018.

Tragically, one young man died as a result of the event, and 22 people, including 3 firefighters, were transported to hospitals for treatment of their injuries. 

On behalf of my colleagues on the Board and the entire NTSB, I offer our sincerest condolences to the families and friends of the man who lost his life. To those who were injured, we wish you the fullest possible recovery.

The explosions and fires damaged 131 structures in Lawrence, Andover, and North Andover, some of which were completely destroyed.

The disruption to life in the Merrimack Valley did not end there. Roads were shut down, gas and electric service were cut off, and more than 50,000 residents were asked to evacuate.

The statewide Fire Mobilization Plan was triggered, activating 15 task forces across the state. More than 180 fire departments and 140 law enforcement agencies responded to the scene.

Residents were allowed to return to their homes three days later, but in many homes, gas for cooking, heat, and hot water, was not restored until December. Many residents spent months in apartments, hotel rooms, and mobile homes provided by NiSource, the parent company of Columbia Gas of Massachusetts, or CMA.

The safe transportation of hazardous materials is on the NTSB’s Most Wanted List of Transportation Safety Improvements. After the Merrimack Valley event, it’s clearer than ever why it made the list.

The overpressurization event happened during replacement of an old cast iron gas main. Done right, that cast iron replacement is part of a risk mitigation strategy to prevent natural gas releases, due to leakage from aging cast iron piping.

But those two little words, “done right,” cover a lot of scenarios, and NiSource’s risk assessments and safety review covered fewer. The project was done wrong.

The results were not simply unacceptable. For a whole region, they were catastrophic.

As a result of this catastrophic event, last year, we issued safety recommendations to help ensure that such projects are done right in the future. Thankfully, NiSource and the Commonwealth of Massachusetts acted on them quickly. Now a professional engineer (PE) must review and seal engineering drawings in one more state, and in subsidiaries of one parent company. However, there are many other states and companies in which PEs are not required to review such plans, and that leaves glaring gaps.

A PE’s seal stakes an expert’s career on the completeness of the planning process before work begins on a project. But it still relies on a human being, who is subject to human error.

So today, we will also consider more robust protection against overpressure incidents.

Finally, we will discuss the multijurisdictional emergency response to the event. The number of uniformed responders and resources dispatched in response to the emergency was breathtaking. But we’ll look at ways to improve communications and coordination among first responders on-scene, including those working for NiSource and CMA. We will also discuss ways to improve preparedness among NiSource and CMA personnel.

The NTSB staff has pursued all avenues and will briefly present the pertinent facts and analysis found in the draft report. They will present findings, a probable cause, and recommendations to the Board.

We on the Board will then question staff. We will also propose and vote on any amendments necessary to ensure that the report as adopted truly provides the best opportunity to enhance safety.

The public docket for the accident is available at It contains additional information, including photos, interviews and affidavits, and factual documentation gathered during the investigation. Once finalized, the accident report will also be available on our website.

Now, Managing Director Sharon Bryson, if you would kindly introduce the staff.