Columbia Gas of Massachusetts is aiming to have natural gas service restored to all residential and commercial customers by Nov. 19 and has begun the “massive replacement program” of the utility’s distribution system following a series of explosions on Sept. 13 in Merrimack Valley near Boston.

In a joint press conference hosted by parent company NiSource, CEO Joe Hamrock and Gov. Charlie Baker, Hamrock outlined the next phase of recovery and replacement activities for the Greater Lawrence Area, including bringing immediate help to people who need it most.

"Many people are still hurting in the wake of last week's disaster," Hamrock said. "We owe it to this community to fully address the community's needs and rebuild your trust in us."

A preliminary investigation of the explosions by the National Transportation Safety Board pointed to an issue with the regulator that controls the gas flow between high- and low-pressure parts of the system, which may have permitted “significantly greater flows and pressure” into structures in Lawrence, Andover and Lower Andover.

One man was killed after a chimney blew off a home and crushed the vehicle in which he was sitting. About two dozen people were injured and up to 80 structures were damaged or destroyed in the blasts.

One day after the explosions, Baker, who was critical of the utility’s initial response to the explosions, declared a state of emergency, under which he put utility Eversource Energy in charge of responding to the emergency. Eversource reported finding another gas leak on Sept. 15 near the scene of the fires. Baker also instructed the Department of Public Utilities to request that Columbia Gas hire an outside contractor to lead its recovery efforts.

On Friday, Columbia Gas said Joe Albanese, founder and CEO of Commodore Builder, a construction management firm, would serve as the chief recovery officer for the project. He will be assisted by Richard E. Cellon, president of business management consultant Cellon and Associates.

Over the weekend, with the assistance of the Massachusetts National Guard, Columbia Gas began providing nearly 7,000 self-contained hot plate units to customers who need them for cooking until natural gas service is restored. On Monday, some 60 Columbia Gas and contracted construction teams began the massive replacement program in all three communities, which will ultimately replace the 48-mile cast iron and bare steel distribution system with “state-of-the-art” infrastructure and safety features such as excess flow valves that automatically shut off gas flow if a service line is damaged or broken.

"We will return natural gas services as quickly as possible -- but our core commitment to safety will underpin these efforts," Hamrock said. "Services will be restored only after new facilities have been fully inspected, tested and proven safe."

Teams of electricians, plumbers and assessors will also begin electrical assessments and install 24,000 space heaters in homes this week, Hamrock said. Before installation, local fire chiefs and electricians must certify that a dwelling is safe for a space heater to operate without risk of fire hazards. For places that do not meet these criteria, the team is exploring alternative home heating options, Columbia Gas said.

On Wednesday, recovery teams are set to begin deployment to every impacted residence or business to do a full assessment and determine what appliances need to be replaced or repaired, which the company has said will take several weeks to be completed. In addition, the team is in the process of evaluating all 48 miles of pipeline that service approximately 8,600 meters and will prioritize affected systems and address those immediate concerns first. Preliminary work to restore service for a very limited number of customers is also underway, Columbia Gas said.

Columbia Gas of Massachusetts is in the midst of a multiyear program to modernize its gas distribution system and replace cast iron and bare steel pipeline systems across the state. NiSource is one of the largest fully regulated utility companies in the United States, serving about 3.5 million natural gas customers and 500,000 electric customers across seven states through its local Columbia Gas and NIPSCO brands.