HAMPDEN – A stubborn fire buried inside one of the state’s largest landfills reignited Wednesday and burned into the evening as officials worked to repair a broken pipe that fueled it.

Fire crews from four towns converged on Pine Tree Landfill on Wednesday afternoon prepared to battle the fire while landfill workers carefully unearthed the pipe, which is part of an extensive network of plumbing that extracts gases from the landfill.

A broken T-joint that linked two pipes was isolated and replaced Wednesday evening under the supervision of the state Department of Environmental Protection, Don Meagher, manager of planning and development for Casella Waste Systems Inc., which owns the landfill, said Wednesday.

Fire crews then piped in foam under the waste to smother the fire, he said.

“We have found the leak,” he said. “We’re now going to start at the edge of the hot spot and chase it.”

Oxygen drawn into the fire through the broken T-joint fueled the fire, not methane gas inside the pipe, Meagher explained.

Meagher said early Wednesday evening that he did not know the depth or extent of the fire, which was located on the landfill’s southeast side.

The fire had the potential to be uncommonly dangerous because of its connection to the gas collection system, which holds concentrated amounts of methane and allows oxygen to be introduced under the surface, authorities said.

Fire crews were forced to attack a fire of unknown extent that they couldn’t even see, Hampden Town Manager Susan Lessard said Wednesday.

The Pine Tree fire marks the first time in the state that a landfill fire has ignited in connection with a gas collection system, Cyndi Darling of the state DEP said Wednesday.

The system collects gases from within the landfill which then are vacuumed to a flare that burns them off and reduces much of their accompanying odor.

Nearby residents were not notified of the fire, and truck traffic to and from the landfill continued Wednesday without interruption, Meagher said.

“There really is no risk off-site at all,” he said.

The fire was sparked Nov. 20 by the spontaneous combustion of decomposing waste, as is typical of most landfill fires. After Pine Tree workers noticed smoke rising to the surface, Hampden firefighters doused the fire with water and thought it was extinguished.

The fire came to landfill workers’ attention again Tuesday during a training session on the gas collection system, Meagher said. The gas-burning flare briefly went out when an engineer attempted to adjust the system’s low methane levels, he said.

When the flare went out, the smoke again began to surface, Meagher said. That pointed to a connection between the gas collection system and the fire and eventually led officials to the broken pipe, he said.

Essentially, the fire and smoke were being drawn up through the pipe to the flare, so no one noticed it, Meagher said. When the flare went out, the system’s suction automatically shut off, allowing oxygen to get in and smoke to rise to the surface, he said.

The fire could be related to a leak of methane gas on the opposite side of the landfill discovered earlier this month, Meagher said.

The gas is leaking from a hole in a liner that covers the oldest section of the landfill, which was opened to relieve pressure from an accumulated bubble of methane. The liner is being left unsealed as DEP and Pine Tree officials try to reach an agreement about how to fix the problem.

The gas collection system may lack adequate suction to collect gas from around that leak, Meagher said.

Both the methane leak and the fire come at a bad time for Casella, which is in the midst of trying to get approval for an expansion at Pine Tree.

The expansion would boost the 6 million-cubic-yard landfill’s capacity by nearly 50 percent. The project is on hold while the DEP determines whether the added capacity would benefit the public.

As the operator of the West Old Town Landfill, Vermont-based Casella also is negotiating a host community agreement with the city of Old Town.

City Manager Peggy Daigle said she was worried about the Pine Tree fire, because the system that’s slated to be installed at West Old Town is almost identical to that at Hampden.

“We would be concerned as to wanting to know why the fire occurred, and what steps are going to be taken to keep it from happening out at Old Town,” she said.

Fire at the landfill was one concern expressed by We the People, a group opposed to the landfill deal that’s trying to get the project’s approval reversed, when the West Old Town Landfill idea was introduced.

“You don’t know what kind of damage it’s creating at the landfill to cause other environmental problems,” Debbie Gibbs, a resident of Alton and member of We the People, said Wednesday.

While concerned about the fire and its connection to the gas collection system, Hampden Town Manager Susan Lessard said she was pleased that Casella promptly reported the problem. The notification allowed the town to work with officials from other municipalities, Pine Tree and the DEP to prepare a response plan, she said.

“Instead of waiting for something to blow up, we’re on scene with adequate staff numbers with sufficient equipment,” Lessard said.

Crews from Hampden, Hermon, Newburgh and Winterport were at the scene, as well as a tanker truck from the Bangor Air National Guard base, she said. The Bangor Fire Department also was on standby, she said.

The extent of the fire remained uncertain early Wednesday evening, but crews were expected to remain on the scene into the night.

“I hope this is just a really good opportunity for mobilization, but we’re prepared in case it isn’t,” Lessard said.

BDN writer Aimee Dolloff contributed to this report.