The southern Maine natural gas provider Unitil has asked regulators to raise its base revenue by $6 million to cover infrastructure investments, in a move that would raise the average residential heating bill by almost $9 a month.

Regulators are now reviewing the request that would raise the heating bill for the utility’s average residential customer by $8.66 per month, or 9.2 percent.

At the end of 2016, the company served 31,908 Maine customers in 25 southern Maine communities, including Portland, South Portland and Westbrook, according to regulatory filings. It also serves parts of York County and the Lewiston-Auburn area.

The company said it’s requesting the increase to fund long-term infrastructure investments, replacing pipelines in its distribution system “while at the same time pursuing an aggressive expansion of its natural gas distribution system.”

“The primary driver of this rate relief is the ongoing investment the company continues to make to replace and upgrade its existing gas distribution system,” said David Chong, treasurer for the Unitil subsidiary operating in Maine, Northern Utilities Inc.

The company requested the increased rates take effect on July 1, but regulators postponed the new rate schedule until Oct. 1 or until they have adequate time to review and consider the request.

According to a notice sent to utility customers, the rate request would raise Unitil’s revenue from gas distribution charges by 14 percent.

For its largest customers, the utility projects a lower increase in rates, with the average customer with high year-round use seeing a rate increase of 3.6 percent, or $1,435 per month.

Chong said the company’s costs have risen faster than its revenues since 2013 and the company needs to compensate for that. To cut costs, he said that Unitil has closed its pension plan to union and non-union employees and plans to save by switching to a new medical insurance provider later this year.

Darren Fishell

Darren is a Portland-based reporter for the Bangor Daily News writing about the Maine economy and business. He's interested in putting economic data in context and finding the stories behind the numbers.