HAMPDEN – Methane gas that is escaping from Pine Tree Landfill is stinking up town and could for weeks to come while state and landfill officials hash out a solution.

The gas is leaking from a hole in the liner that covers the oldest section of the landfill, which was built in 1975, town and Pine Tree officials told a group of roughly 50 people Monday at a special Town Council meeting.

The meeting was held to discuss a variety of landfill topics, including solid waste legislation, a proposed expansion at Pine Tree and the continuing odor problem.

After the last of the oldest section of the landfill was covered in September, methane accumulated and caused a bubble in the liner. Landfill workers, in consultation with the state Department of Environmental Protection, unsealed the liner around the bubble to vent the gas later that month, but the methane ignited when a contractor attempted to heat-seal the liner back into place.

The contractor was not injured in the explosion.

The liner now is being left unsealed as gas continues to create pressure within the landfill, and as DEP and Pine Tree officials try to reach an agreement about how to fix the problem.

Meanwhile, the resulting odor remains and could for several more weeks.

“We are as aware of it as everybody else is,” Don Meagher, manager of planning and development for Casella Waste Systems Inc., which owns the landfill, said Monday.

Casella officials want to install a pipe to extract the gas, but that would require penetrating the liner, an approach the DEP has forbidden because of concerns about potential future leakage.

“We had an explosion, there’s that much gas there,” Marty Drew, Pine Tree’s general manager, said Monday. “We’re in a Catch-22. We think we have a solution; [the DEP] thinks they have a policy.”

DEP officials were not present at Monday’s meeting.

Even if a temporary fix is devised, the problem isn’t going away anytime soon. As the waste in the oldest section of the landfill continues to decompose, it will generate methane that needs somewhere to go. Even weighing down the liner with waste – one solution that’s being discussed – would force the gas down into the soil and into the surrounding groundwater.

“We’ve literally entombed the old, 21-acre landfill,” Drew said. “That 1975 landfill is still cooking.”

Even before the explosion, methane gas was detected in groundwater at the site, an issue that should be resolved before Casella’s application to increase capacity at the landfill is considered, Bill Lippincott, who heads a local coalition that opposes the proposal, said at Monday’s meeting.

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 expansion would benefit the public.

Several residents questioned the need for more capacity at the landfill, while Casella officials argued that Pine Tree, despite its odor problem, is vital to the state’s waste disposal strategy.

“Landfills are essential public infrastructure,” Meagher said. “We really can’t do without them.”