US federal regulator blames utility for Massachusetts gas network blasts
20 November 2018
The US National Transportation Safety Board (NTSB) said on November 15 that utility company NiSource failed to adequately draft and oversee natural gas pipeline work orders and those lapses led to deadly blasts in three Massachusetts communities in September. The federal regulator said ineffective oversight of works by Columbia Gas Co of Massachusetts, a subsidiary of NiSource, was responsible for the disaster.
Explosions and fires killed one person, injured 21 and damaged 131 buildings in the towns of Lawrence, North Andover and Andover, Massachusetts, on September 17 as Columbia Gas replaced cast-iron pipes with plastic lines.
State regulators are overseeing the replacement by utilities of thousands of miles of old natural gas pipelines in Massachusetts to reduce leaks.
The NTSB said that a field engineer who developed the work orders, told investigators that he did not recognise the critical role of pressure sensors in the pipes where work was taking place which resulted in the network being flooded with high-pressure gas.
The agency recommended that NiSource revise its review process, update its records and documentation and be able to immediately shut down gas pipeline systems during repairs. It said Massachusetts should require professional engineers to sign off on utility company work orders, which is not currently required.
NiSource, based in Merrillville, Indiana, said in a statement that it would adopt the agency’s safety recommendations at all of its utility companies, and spend $150 million to install devices that would close gas lines when they sense pressure reaching risky levels.
NiSource said the “slam-shut” devices would be in operation continuously, not only when work was underway, and would operate like circuit-breakers. The program would also include installing remote monitoring devices on all low-pressure systems so that gas control centres had the ability to monitor pressure at regulator stations in real time, 24/7.
It said it had also conducted a field survey and engineering review of regulator stations and would ensure NiSource personnel were present whenever excavation work is being done in close proximity to a regulator station.
The company said in a regulatory filing this month that the US Attorney’s Office in Massachusetts was conducting a criminal probe of the company as a result of the disaster.
It was the largest US natural gas pipeline accident since 2010 in terms of structures involved.
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