The construction work involved replacing aging pipes in the area with plastic lines. But the National Transportation Safety Board said the utility failed to tell the construction crew about disconnecting or relocating the sensor, allowing the device to detect a drop-off in pressure in the abandoned line and signal to a nearby control station to increase the flow of gas into the system.
That elevated gas pressure to dangerously high levels, overwhelming the system and setting off fires across Lawrence, North Andover, and Andover. Five homes exploded and 125 structures were damaged by fire. One person was killed when a collapsing chimney fell on him, and two dozen others were injured.
Over-pressurized gas lines caused fatal explosions near Boston, NTSB says
The preliminary report by the NTSB said Columbia was responsible for the construction plans for the work crew and had an inspector at the job site, at the intersection of South Union and Salem streets.
NTSB: Columbia Gas signed off on disaster
Industry analysts said the report also raises concerns about safety protocols during the replacement of gas pipelines, and whether an inspector or a contractor involved in such work should have known enough to check the sensors.
The preliminary findings on the Sept. 13 explosions and fires, which hit Lawrence, Andover, and North Andover, were released Thursday by the National Transportation Safety Board.
“It left a lot of questions to be answered,” said Mark McDonald, president of NatGas Consulting, a Boston-based company that investigates gas explosions and is representing some victims of the incident. “There were other stopgaps that should have been in place to stop this from happening.”
The first related 911 call from Lawrence came in at 4:11 p.m.. Six and seven minutes prior, a monitoring system received two high-pressure alarms but that system did not have the ability to close the valves.
Richard Kuprewicz, a pipeline safety specialist and adviser to the federal Pipeline and Hazardous Materials Safety Administration, said the NTSB report is preliminary and was expected to be incomplete, but added, “There are some important details missing.”
He expects a final report to look at other factors, including “what should the contractor have known.”
Video: The Springfield jeweler Smith and Son reached a milestone on Thursday.
What is clear, Kuprewicz said, is that “a low-pressure system got hit with very high pressure and for quite a while.”
Since the Sept. 13 disaster, Columbia Gas has upgraded its policies and procedures related to this type of pipe replacement work. And on Thursday, the state Department of Public Utilities, which regulates the industry, mandated new safety protocols for Columbia and other local utilities to guard against overpressure situations. The companies were ordered to cease all work involving connections between high- and low-pressure systems to review their procedures, and take additional steps, such as verifying the location of sensing equipment during construction.
“The release of the preliminary report raises more questions than answers about how the Merrimack Valley disaster occurred, and I will not stop until we get each and every answer,” Markey said in a statement. “We need to turn over every stone and shine a light on the workings of this company and the entire industry, so that people can both trust that their gas system is safe and verify that nothing like this will ever happen again. The fate of families and small businesses depends on it.”
Columbia Gas said in a statement following the NTSB report that it could not speculate or comment on the final cause of the disaster, because the investigation is ongoing. But the utility noted it suspended all similar work and enhanced procedures for work on low-pressure systems after the disaster occurred.
“We saw these as responsible steps to take in the aftermath of the incident and while the facts were being gathered,” Joe Hamrock, chief executive of NiSource Inc., the utility’s parent company, said.
The NTSB report did not name the Columbia Gas contractor in its report, but the Dorchester-based Feeney Brothers has previously acknowledged it was working at the Lawrence site that day.
“All of Feeney Brothers’ work was done with Columbia Gas’ oversight and according to written procedures provided to our crew by Columbia Gas, as confirmed” by the NTSB report, the company said in a statement Thursday.
Senator Edward J. Markey, who has pushed Columbia for more explanation of the Lawrence disaster, said the NTSB report raises more questions than it answers.
Feds release preliminary report on Merrimack Valley gas explosions
“For the most part, the report is not telling us anything that local residents don’t already know. They know that Columbia Gas company did not respond quickly enough. What we don’t know is how could the catastrophe have occurred. Could it have been prevented?” he said.
The work involved the replacement of a cast-iron, low-pressure distribution system that was installed in the early 1900s. Gas pressure to the affected area was controlled by 14 regulator stations.
The NTSB report lays out the immediate sequence of events of Sept. 13. At 4:04 p.m., a Columbia Gas monitoring center in Columbus, Ohio, received the first of two alarms indicating high pressure in the Lawrence system; the second came a minute later.
However, the monitoring center had no ability to remotely control the pressure valves, which required manual work. A controller in Ohio instead reported the alarms to local Columbia Gas officials in Lawrence at 4:06 p.m. The first 911 call by a resident in Lawrence was at 4:11 p.m.
NTSB releases preliminary report on Merrimack Valley gas disaster
The regulator station at issue was shut down by 4:30 p.m. And the critical valves for the distribution network were shut off by 7:24 p.m.
By midnight, crews began to shut off meters at individual homes and businesses, to isolate them from the distribution system. All meters were shut off by the following morning.
Ed Markey prods feds to turn over every stone in Columbia Gas probe
McDonald, the industry analyst, said he expects the final NTSB report will look at the official cause of the disaster, but also reflect on state policies and protocol, as well as the state of an aging gas distribution system, among the oldest in the country.
The disaster has left thousands of homes and businesses without gas heat or hot water as cold weather arrives, while Columbia Gas races to replace 45 miles of pipeline that were damaged by the over-pressurization. The company, which tapped retired Navy Seabee commander Joseph Albanese to lead the response effort, has said it is far ahead of a Nov. 19 deadline it set to replace the pipeline.
But the effort has been complicated by the need to replace gas appliances and meters in many homes. Albanese has said that no property will be reconnected until it is deemed “house ready,” with safely connected appliances.
That effort has moved more slowly, though officials are optimistic about hitting the Nov. 19 deadline.
Columbia has said it will reimburse residents and businesses for all expenses and incurred losses. By Thursday, more than 3,000 people had been placed in temporary housing, such as hotels, apartments, and trailers.
“We are working to restore gas service as quickly as possible and are committed to taking the steps needed to re-earn the trust of our customers, communities, and public officials,” Hamrock, the company executive, said in a statement.
Paul Oleksa, a pipeline safety consultant based in Ohio, said the NTSB report leaves open many questions about the incident. But he said the response plan was impressive.
“This new system will have a pressure regulator at each individual house, each individual customer, and it’s a much better system,” he said. “It should give a great deal of relief to individual customers and to the public.”
HOUSTON (Reuters) – A NiSource Inc affiliate failed to require contract repair crews to relocate pressure sensors during natural-gas pipeline work, the National Transportation Safety Board (NTSB) said on Thursday, resulting in overpressured lines that caused explosions and fires in three Massachusetts communities last month.
Overpressurized gas poured through Columbia Gas Co of Massachusetts distribution system in Lawrence, North Andover and Andover, flooding into homes and businesses and sparking explosions and fires that killed one person and injured 21.
Critical valves controlling the gas flow were not shut for nearly 3-1/2 hours after the first alarm was raised at Columbia Gass monitoring center, NTSB said in a preliminary report. The center had no ability to remotely open or close valves on its own, but did notify technicians, it added.
NiSource is fully cooperating with the NTSB, Chief Executive Joe Hamrock said in a statement on Thursday. However, it will not comment on the cause of the incident until the NTSB completes its work, he added.
The incident raised safety concerns about the sprawling U.S. networks of aging pipelines. The September explosions and fires damaged 131 homes and businesses as Columbia Gas was replacing cast-iron pipe with safer plastic lines when the accident occurred.
Crews were working for Columbia Gas in Lawrence, a city northwest of Boston, to replace an aged cast-iron main with a new plastic distribution main line. The abandoned main had regulator sensing lines used to detect pressure in the system.
After that main line was disconnected, the sensing lines lost pressure and the regulators fully opened, “allowing the full flow of high-pressure gas into the distribution system supplying the neighborhood,” the report said.
Columbia Gas had approved a “work package (that) did not account for the location of the sensing lines or require their relocation to ensure the regulators were sensing actual system pressure,” according to the NTSB.
Minutes before the explosion, Columbia Gas monitoring center in Columbus, Ohio, received high pressure alarms for its South Lawrence gas pressure system. The company shut down the regulator at issue about 25 minutes later, around 4:30 p.m, the NTSB said.
Septembers explosion was the largest U.S. natural gas pipeline accident since 2010 in terms of structures involved. Eight years ago, an interstate gas transmission line operated by Pacific Gas and Electric Company ruptured in San Bruno, California, killing eight people, destroying 38 buildings and damaging 70 others, according to the NTSB.
Columbia Gas has said all cast iron and bare steel piping in affected neighborhoods will be replaced with high pressure plastic mains that have regulators at each service meter.