Woburn residents not expected to have gas restored until Thursday

An inadvertent over-pressurization of gas lines in Woburn led to a big response from National Grid Monday afternoon.

Police and National Grid crews swarmed the neighborhood around the intersection of Wyman and Lowell streets.

National Grid went door-to-door shutting off the gas at homes as a precaution.

An over-pressurization of gas lines is what investigators say led to the explosions and fires in Lawrence and North Andover just a month ago.

There were no problems immediately reported due to the over-pressurization in Woburn, but workers have been on alert since the catastrophe that killed a teen in Lawrence.

National Grid said a technician accidentally introduced excess gas into a portion of its system while doing regular maintenance at a regulator station at Wyman and Hart streets.

There were no evacuations ordered in the area.

>> MORE: DPU orders moratorium on all National Grid work, except emergency & compliance work

"We’ve got the situation in hand, but I understand the concern," A spokesperson for National Grid said in an email to Boston 25 News. "Right now it’s the inconvenience of homes being without gas. The area is completely safe."

People holding signs protesting the lockout of unionized National Grid workers showed up near the intersection, but it was not immediately clear what led to the over-pressurization.

Locked out National Grid workers, who have been involved in a labor dispute with the company since July, said they weren't surprised by the incident.

"We’ve been saying it out loud," said one locked out worker. "It’s like a ticking time bomb. When you got people who don’t do this work day in and day out and you got the B team in or the C team, this stuff can’t happen."

When asked if the technician involved in the incident was a replacement worker, National Grid said:

"The crew that are involved are management employees, gas technicians who have been with the company for decades," said National Grid Representative Christine Milligan. "They are the folks who normally supervise our unit in place."

Officials said they will be investigating the incident but assured the public there is no danger.

Milligan said it took just minutes for crews to identify there was an issue with the over-pressurization of the gas lines and immediately began fixing it.

Over 100 National Grid crews will be working to shut down gas in their system and then go home-by-home shutting off gas meters individually. According to Milligan, by 4 p.m. Monday about 25 percent of homes already had their gas shut off.

Then, National Grid crews, along with Woburn Police will gain entry into homes if people aren't inside to shut off their gas.

Once crews ensure the system is completely shut off and every gas meter in every home is completely off, they will begin assessing their system and ruling out any damages. National Grid does not believe any damage has been done to the system.

Finally, crews will work on re-energizing and begin the process of re-lighting each home.

Initially, National Grid said gas would be restored to the 300 homes affected by late Monday night and possibly stretching into Tuesday morning. Later, they altered their timeline, saying residents would not have gas restored until Thursday.

"I apologize for that, we actually were right in the middle of doing our engineering plan," said Marcy Reed, National Grid's Massachusetts President. "We’ve segmented the neighborhood here into five zones and just the time it’s going to take to get to all five zones, we want to do this right."

National Grid insists the crews working on this problem are capable and have full confidence in their work.

Schools in the area will still have classes on Tuesday.

Milligan emphasized this incident is completely unrelated to the recent Merrimack Valley explosions.

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Cox Media Group