The state is investigating what may be its largest-ever spill of leachate from a landfill –the North Country Environmental Services facility in Bethlehem, owned by Vermont waste company Casella.
The state Department of Environmental Services says the incident began late on May 1, a Friday, and lasted until the following Monday.
Operators arrived to find that a leachate tank had been overflowing all weekend, spilling as much as 154,000 gallons of what’s often called “garbage juice.”
The landfill does not accept trash on weekends and was not staffed while the overflow occurred, according to the state.
Leachate is a combination of rain and liquid garbage, contaminated with heavy metals and other chemicals, which percolates through solid waste at landfills. It’s usually pumped into holding tanks, then into trucks that haul it to wastewater treatment plants.
In this case, the state and Casella say they believe an automated signal failed to fire when a leachate holding tank were full – meaning the liquid kept trying to pump into the tank with nowhere to go.
The tank overflowed, and the leachate traveled through an obsolete pipe that the state says Casella should have decommissioned after a recent expansion.
According to the state, the leachate made it into, and then out of, a surface water detention pond surrounded by a grassy swale on the side of the facility nearest the Ammonoosuc River. Casella, for three years, has been fighting a federal lawsuit alleging they contaminated the river.
The state says this leachate spill was much larger than most they deal with on a routine basis. Those spills usually involve a leak from the 8,000-gallon leachate trucks that empty the landfill’s holding tanks and take the liquid offsite.
A DES official couldn’t recall another leachate spill this large. He called the incident “significant” and said the state is “concerned” about its causes and potential effects.
It’s not clear exactly how much leachate made it out of the detention pond. The state is now sampling nearby soil and groundwater to try and figure that out. They’re also considering potential compliance and enforcement actions against Casella.
Casella spokesman Jeff Weld told NHPR that they don't believe any leachate made it out of the pond, which he said has a 600,000 gallon capacity.
"We continue to work with NHDES on the root cause and evaluation of additional impacts, but it appears there were no offsite impacts due to the engineering design of the retention pond forebay," Weld said.
When the spill was discovered, the state says, the company pumped out the affected pond, excavated the soil inside it and began its own sampling for impacts.
Otherwise, the landfill remains open and operating. On Wednesday, the company broke ground on a new gas capture project there. Meanwhile, landfill opponents are appealing the state’s recent approval of a small expansion for the facility.
This story was updated Friday to include a comment from Casella.