Columbia Gas of Massachusetts will work under an independent engineering firm's oversight as the utility finishes its remaining restoration and recovery work after September blasts in its service territory, the Massachusetts Department of Public Utilities ordered Dec. 17.

The department's order said that the utility must work under the supervision of Massachusetts-based Nitsch Engineering to address all outstanding restoration needs by Oct. 31, 2019.

Specifically, Columbia Gas will have to ensure that all the affected properties have adequate heat and hot water and gas appliances, repave all affected streets and sidewalks, and consult with the affected communities on restoring other affected surfaces, among other things.

During the restoration process, the NiSource Inc. utility will have to maintain quantitative standards tracking the company's progress, the Department of Public Utilities, or DPU, said in its Dec. 17 order. Community leaders where the utility is working will need to verify the progress data, and if Columbia Gas fails to comply with any of the DPU's restoration requirements, the company could face up to $1 million in penalties per violation, the department said.

"With this order, the Department of Public Utilities continues its commitment to holding Columbia Gas accountable to complete all remaining restoration work in a timely, safe and thorough manner," Angela O'Connor, the DPU's chair, said in a statement. "The department will continue to carefully monitor the utilities' recovery efforts while working to ensure the safety of the commonwealth's entire natural gas distribution system and operations."

Columbia Gas, formally known as Bay State Gas Co. recently restored gas service to nearly all meters affected by the series of fires and explosions. The utility had re-lit 95% of the affected gas meters as of Dec. 5, noting at the time that some of the outstanding unlit meters belonged to customers who have chosen to not use Columbia Gas to restore service.

The company's Sept. 13 system overpressurization resulted in fires and blasts in Lawrence, Andover and North Andover, Mass., killing one person, sending at least 21 people to the hospital and damaging 131 structures, in addition to disrupting gas service for thousands.