Days after the natural gas calamity in the Merrimack Valley, Columbia Gas of Massachusetts updated internal policies to require additional oversight and safeguards when performing the same underground pipe work that has been suspected as the cause of the disaster.
The edict raises questions about the company’s previous practices, and whether there was a lack of oversight or safeguards at Columbia construction sites on Sept. 13, when a series of explosions and gas fires ripped through three communities, Senators Ed Markey and Elizabeth Warren said in a new letter to the utility.
“The omission of these sorts of safety measures from Columbia Gas’ operating procedures prior to this disaster is alarming and unacceptable,” the senators wrote, according to a copy of the letter they provided to the Globe. “It raises serious questions as to why these policies were not in place for Columbia Gas’ systems and whether that failure was the result of negligence, cost considerations or incompetence.”
Markey said the updated policy was included in documents that he and Warren had requested about the utility’s safety and emergency response plans. In their letter, the senators questioned a number of Columbia Gas’s internal procedures, including the new instructions about oversight of underground pipe work.
The Sept. 18 update — and Markey’s and Warren’s questions about it — concerns work on the low-pressure gas lines that construction crews perform near regulator stations and control lines, or sensors. This equipment is critical for ensuring that gas flows through the underground network at proper pressure levels and does not overwhelm low-pressure pipes that supply homes and businesses.
In its directive, Columbia Gas instructed crews to verify the location of control lines — which measure gas pressure — before they begin construction and to conduct field surveys to make sure drawings and other records are accurate. “Qualified company personnel” are required to be onsite overseeing any work and to monitor pressure in the system after the construction is finished for a minimum of 30 minutes.
The National Transportation Safety Board, which is investigating the Merrimack Valley catastrophe, has said the Columbia Gas network was over-pressurized at the time of the disaster. The agency has also singled out work on low-pressure pipes in a section of Lawrence as a focus of its inquiries.
Columbia Gas acknowledged the company updated its policies following the disaster but declined to comment, citing the federal investigation.
“As a party to the NTSB investigation, we can’t comment on the cause of the incident,” said Scott Ferson, a spokesman for Columbia Gas. “However, safety is our top priority and that is why, in the immediate hours after the incident, we suspended similar work and enhanced procedures related to our low pressure system.”
The company’s policy in place before the Sept. 13 disaster requires construction crews to review maps and other records before tapping into pipes and to monitor pressure in the system during construction. It recommends that under certain circumstances, “special consideration should be given to monitoring pressure at regulation stations.” But it does not make any specific reference to control lines.
In their letter, Markey and Warren said the new oversight procedures “appear to be common-sense measures that Columbia Gas should have instituted long before the Merrimack Valley disaster.”
One man died, and thousands of residents and businesses were forced to evacuate after more than 80 explosions and fires ripped through sections of Andover, Lawrence, and North Andover late in the afternoon on Sept. 13. At the time, Columbia Gas had been in the midst of a large project replacing older, leak-prone cast iron and steel gas mains in the area.
After the catastrophe, the NTSB said it was interested in work that was done along a section of South Union street in Lawrence. NTSB Chairman Robert L. Sumwalt said investigators found that a disconnected pipe still had a live sensor on it.
In a news conference several days after the incident, Sumwalt said investigators will try to learn “what effect, if any, did this have on the over-pressure situation, and why was the sensor connected to a gas line that was being taken out of service?”
NTSB spokesman Keith Holloway said agency investigators “will look at the procedures that were in place at the time of the accident; and if there are issues with the procedures, NTSB will address those as part of its investigation.” He added the agency may have an update on its investigation next week.
The Massachusetts Department of Public Utilities, which reviews gas companies’ operations policies annually, said Columbia’s early procedures met minimum standards set by the federal government and that the additional checks exceeded those requirements
The DPU plans to hire an independent evaluator to examine the safety of the natural gas distribution system statewide, including the operations and maintenance policies and practices of utilities “to ensure proper safety protocols are in place,” spokesman Peter Lorenz said.
Mark McDonald, president of NatGas Consulting, a Boston-based company that investigates gas explosions, said Columbia Gas’s initial policy failed to follow industry standards and shouldn’t have been approved by the DPU.
“Columbia Gas has a responsibility to make sure these regulator stations are protected, particularly from its own subcontractors,” said McDonald, who is representing some of the victims of the Merrimack Valley catastrophe.
He said the DPU should have acted as a “stop gap” to prevent Columbia Gas’s “failure to enforce the safe industry minimum standard.”
Thousands of residents and businesses in the three communities remain without gas service, while Columbia Gas conducts a massive replacement of 45 miles of gas mains and some 6,100 service lines to properties. The utility has called in nearly 200 construction crews and several thousand workers, and is racing the onset of cold weather to have the replacement work finished by Nov. 19.
The new work procedures require several briefings among crews and supervisors to plot the construction work in detail and ensure proper monitoring of regulators. A “field survey” of regulators and controls must also be conducted.
Markey said the policy changes indicate that Columbia Gas “agrees that their procedures were not adequate, that they have to be changed if they are going to avoid disasters in the future.”
Markey and Warren said their review of Columbia Gas operations turned up other worrisome practices. They said the company’s internal policies indicated lax oversight and emergency plans that did not contemplate a disaster of the scale that occurred in greater Lawrence.
The senators said:
■ The company’s plans downplayed potential risks, including the potential for over-pressurization of an entire system and operator error;
■ Its guidelines were “too vague” on how employees should respond to over-pressure alerts and conduct an emergency shutdown of the system;
■ Columbia Gas has not finalized a Pipeline Safety Management System that the American Petroleum Institute recommended in 2015, with input from federal regulators;
■ Its emergency response plan did not lay out a timeline for communicating with the public.
“Taken together,” Markey and Warren said, “these failures to guard against an extremely rare but serious disaster created conditions in which the possibility of such an event was a near certainty.”
Laura Crimaldi of the Globe staff contributed to this report. Matt Rocheleau can be reached at matthew.rocheleau
@globe.com. Follow him on Twitter @mrochele Shelley Murphy can be reached at shmurphy
@globe.com. Follow her on Twitter @shelleymurph. Milton J. Valencia can be reached at firstname.lastname@example.org. Follow him on Twitter @miltonvalencia.
Because of a reporting error, a story in Friday’s Metro section incorrectly identified the name of Mark McDonald’s business. He is president of NatGas Consulting, a Boston-based company that investigates gas explosions. The Globe regrets the error.