LAWRENCE (CBS) – Columbia Gas said Tuesday that it has finished replacing miles of pipeline as it works to restore gas service to customers in the Merrimack Valley.

The company was in the process of pipeline upgrades on Sept. 13 when an accidental over pressurization of a gas main sparked dozens of explosions and fires in the area, killing one person.

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More than 43 miles of main lines are now “gas-ready,” Columbia said, three weeks ahead of schedule.

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Columbia Gas crews repairing damaged lines in Lawrence Saturday. (WBZ-TV)

However, many residents could still be weeks away from seeing their gas service restored. Columbia Gas had previously set a deadline of Nov. 19 for complete restoration, but last week pushed that date back to Dec. 16 at the latest.

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Columbia Gas says it has received 21,944 claims and paid out $34.2 million. They have relit 1,390 residential customers and 84 businesses. So far, 1,925 families have been placed in alternative housing.