Portland, ME – State regulators ordered an in-depth investigation of safety practices at Northern Utilities on Tuesday after a recent string of

natural gas leaks caused a house explosion, two fires and mass evacuations in several southern Maine towns.

The Maine Public Utilities Commission said it wants to determine whether there are systemic problems with the way the gas utility is managed.

Since December, the state has investigated six incidents linked to Northern Utilities and has cited the company for probable violations in four cases.

“These incidents compel us to question whether Northern is managing safety operations as effectively as it should,” Commission Chairman Kurt Adams said in a prepared statement.

The latest incidents occurred within a week of one another.

On Monday, a gas leak forced the evacuation of a dozen homes in Cape Elizabeth.

The week before, a gas explosion leveled a vacant home in South Portland after a construction worker clipped a gas line nearby.

In that instance, the utility had marked gas lines in a “reckless or negligent manner,” according to a PUC investigator who alleged

a probable violation and proposed a maximum penalty of $5,000.

Northern Utilities said Tuesday it has been working with the state on the incidents and would continue to cooperate fully with the newly announced investigation.

The company serves more than 25,000 households in southern Maine.

Spokeswoman Sheila Doiron maintained that the utility provides safe and reliable service, and called the recent gas leaks a “coincidence of timing.”

“In general, the service that we provide goes without incident,” Doiron said.

With its investigation, the PUC said it hopes to develop a picture of day-to-day operations at Northern Utilities through interviews with workers and a review of records.

Pending the findings, the PUC is asking its staff to analyze issues such as the utility’s ability to ensure safe excavations by third-

party contractors, and how it deals with municipal road projects that involve paving over gas lines or valves.

The PUC also wants to know whether homeowners are receiving appropriate notice that there may be live gas feeds running through their basements.

Peter Durgin of Cape Elizabeth said he had been told by Northern Utilities that the gas in his Oakhurst Road home had been shut off last year. But he said he could smell gas Monday as he removed piping from his home for a renovation project, and notified authorities.

Central Maine Power shut off electricity to most of Cape Elizabeth and part of South Portland, and Durgin’s neighbors were evacuated.

“It was a very unsettling event,” Durgin said Tuesday. “I was very frightened, given the danger of gas (igniting).”

Northern Utilities first fell under state scrutiny in December, when PUC staff issued a notice of probable violation over how

the utility manages operations. Staff pointed out, among other things, that the utility failed to have a qualified technician perform a particular task.

The following month, PUC staff issued another notice for potential violations, including lapses in record-keeping.

Northern Utilities’ issues were being worked out quietly with PUC staff until an April incident forced alleged problems into the public eye.

A pressure surge in Northern’s gas lines started two fires in Saco and forced the evacuation of 92 homes and businesses, including a residential-care facility.

The PUC issued another probable violation notice, faulting Northern Utilities for failing to prevent the problem even though it had experienced a similar pressure surge on a gas line it operates in New Hampshire.

The PUC also said the utility operated its Saco distribution lines at five times the maximum allowed pressure and failed to design its system to handle overpressuring.

The company made news again that month when an explosion destroyed a house served by both propane and natural gas in Portland’s West End.

To date, the evidence does not suggest that Northern Utilities’ maintenance practices contributed to the event, said PUC spokesman Fred Bever.

“But we await final test results,” he