Almost three years after high levels of PFAS were detected at a closed landfill in South Hero, officials still don’t know where the toxic chemicals at the site came from.
In December, a monitoring well at the landfill showed about 3,570 parts per trillion of PFAS — much higher than the state’s safe standard for drinking water, which is 20 ppt. The chemicals have not been detected in drinking water supplies near the site.
James “Buzz” Surwilo, an environmental analyst with the state’s solid waste program, said it is “really surprising” to find this level of PFAS contamination in a rural landfill, since the chemicals are more common at sites with commercial or industrial waste.
“Where this has come from is really anybody’s guess,” he said.
Per- and polyfluoroalkyl substances, or “PFAS,” are a family of thousands of chemicals sometimes called “forever chemicals” because they do not break down naturally in the environment.
PFAS are linked to health effects including cancer, behavioral and developmental problems in infants and children, fertility and pregnancy problems, and immune system problems.
Vermont regulates the level of five specific PFAS in its drinking water — PFOA, PFOS, PFHxS, PFHpA and PFNA. Any combination greater than 20 ppt is considered toxic.
Officials monitor many closed landfills for PFAS and calculate each site’s sum of those five chemicals, if any are detected. The 3,570 ppt reading in South Hero is the current highest at any closed landfill in the state, according to data reviewed by VTDigger.
Since 2016, one or more monitoring wells at 20 closed landfills reported PFAS levels above the state’s safe standard for drinking water, Department of Environmental Conservation data shows. Some reports did not reveal exact levels of certain chemicals, so the total could be higher.
A second monitoring well at the South Hero site reported about 500 ppt of PFAS in December, according to the data.
Surwilo said the state began monitoring closed landfills for PFAS after the chemicals were found in Bennington drinking water wells near two former ChemFab factories in 2016. The discovery spurred local outrage, and a class-action lawsuit followed.
In March 2020, PFAS were also found in the groundwater near the Vermont Air National Guard Base in South Burlington. The contamination was mostly due to the use of now-banned firefighting foam, according to a draft report.
PFAS can be found in a number of consumer products as well, including food packaging, nonstick cookware, cosmetics and water-resistant clothing.
David Carter, chair of South Hero’s Selectboard, said the landfill closed in the 1990s. No locals remember any manufacturing in the area that could have produced toxic waste, he said — so there’s a chance the contamination is from household products.
Last month, engineers installed additional monitoring wells to see if contaminated groundwater is migrating beyond the landfill site. The surrounding land has shallow bedrock, Surwilo said, which makes it difficult to reach groundwater for testing
“We just need more information to figure out what’s going on,” he said.
Don't miss a thing. Sign up here to get VTDigger's weekly email on the energy industry and the environment.