Residents living downwind of a landfill in Orrington are being urged to keep their windows closed as firefighters battle a blaze that could take several days to extinguish.

Thousands of tons of waste were at the former Penobscot Energy Recovery Company incinerator when the fire was first discovered Tuesday evening. Firefighters from nearly a dozen communities responded and successfully contained the building fire. But Orrington Fire & Rescue said Wednesday morning that crews were unable to enter the building to address the nearly 40-foot-tall piles of trash due to concerns about the building's integrity.

“This fire is contained but is still burning and will take several days to fully extinguish,” Assistant Fire Chief Chad Bean said in a news release Wednesday morning. “We strongly encourage all residents of Orrington, Brewer, Bucksport and Hampden to keep their windows closed at this time as this fire is causing a significant smoke problem.”

The Maine Department of Environmental Protection also recommended that residents keep windows closed if they could see or smell smoke, adding that the health effects of the smoke were still unclear as of Wednesday morning. DEP and U.S. Environmental Protection Agency air quality monitoring teams were deployed to Orrington and surrounding towns.

The former PERC facility closed in May last year due to financial problems, leaving behind an estimated 8,000 tons of waste. The plant was a major municipal waste collection point in the Bangor region and the closure forced many cities to divert waste to landfills.

Eagle Point Energy Center purchased the facility earlier this year and plans to resume operations in early 2025 following improvements.

In a statement, Eagle Point Energy said the cause of the fire was under investigation, but the company suspected lithium-ion batteries may have been the cause. The company said the fire caused “negligible” damage to the facility.