National Grid and unions representing the more than 1,200 natural gas workers who have been locked out for months announced a tentative agreement that could bring an end to the bitter dispute.
The utility and union leaders announced the deal in a brief, joint statement late Wednesday night following intense negotiations and increasing concern among state officials who had pressured National Grid to end the lockout.
Details were not released. Union officials said ratification votes would be held by Monday.
The workers, including those who maintain natural gas infrastructure in National Grid's eastern Massachusetts service area, were locked out by the utility in July after a previous collective bargaining agreement expired. National Grid also serves customers in Rhode Island and New York, but workers in those states were not affected.
The company said its proposals to shift certain health insurance costs to employees and replace pensions with 401(k) plans for newly hired workers had been among the major sticking points.
"National Grid began this lockout six months ago by demanding major concessions that would have negatively impacted our members, future employees and the safety of our communities," said John Buonopane and Joe Kirlyo, presidents of the United Steelworkers locals, in a statement Thursday. "Though this has been a lengthy and difficult process, we have emerged with a tentative agreement that provides important protections for our members and the Commonwealth's future natural gas workforce."
Demands by public officials to resolve the dispute intensified following a series of natural gas explosions and fires that rocked three Merrimack Valley communities on Sept. 13, leaving one person dead, 25 others injured, and dozens of homes and buildings damaged or destroyed. The disaster involved a different utility, Columbia Gas, yet heightened safety concerns about the National Grid network operating without hundreds of its most experienced maintenance workers.
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The state Department of Public Utilities ordered a halt on nonemergency natural gas work performed by National Grid in October after a pressurization mishap during routine maintenance interrupted service to hundreds of homes in Woburn. No injuries were reported.
Democratic House Speaker Robert DeLeo and Republican Gov. Charlie Baker were among those who had pressed for an end to the lockout, citing safety issues and the toll the impasse is taking on the workers and their families. Baker signed a bill Monday that would extend unemployment benefits set to expire for the workers later this month, absent a settlement.