The pipeline upgrade work that triggered natural gas explosions and fires in three Massachusetts communities last month is slated to be finished this week ahead of schedule.
Columbia Gas said in a newsletter to customers Monday that replacement of about 45 miles of gas mains and nearly 6,000 service lines across Lawrence, Andover and North Andover should be complete by Oct. 31 -- almost three weeks early.
The company has said previously it won't meet a Nov. 19 deadline for restoring gas service to all customers. It now expects to complete that work by Dec. 16.
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Thousands of customers have been without gas since the Sept. 13 incident that killed one person, injured 25 others and damaged or destroyed more than 130 structures.
Investigators have blamed overpressurization of gas lines.