Vermont officials are asking the South Hero Selectboard to further investigate the extent of PFAS contamination at the town’s closed landfill, where previous testing uncovered the highest amount of “forever chemicals” of any similar facility in the state.
In a letter sent to the town last week, the state Department of Environmental Conservation requested a plan evaluating the risk of contamination to water in the bedrock at the site, and laying out potential corrective actions.
Four drinking water wells and a small pond within a half-mile of the landfill showed no significant presence of PFAS when they were tested in 2019. Still, work at the site “has not fully defined the scope and extent of the contamination,” the letter states.
Per- and polyfluoroalkyl substances, or PFAS, are a family of thousands of substances sometimes called “forever chemicals” because they do not break down naturally in the environment.
The chemicals are linked to health effects that include cancer, behavioral and developmental problems in infants and children, fertility and pregnancy problems, and immune system problems.
Monitoring wells at the roughly 3-acre landfill, located off Dubuque Lane, have detected high levels of PFAS multiple times since 2018. That year, the state requested that groundwater at all closed and regulated landfills in Vermont be tested for the chemicals.
In November 2021, six wells at the South Hero landfill were tested for PFAS. Two of those wells have been there since the 1990s, when the facility was closed, and four were installed in 2021. All but one showed contamination well above the level that Vermont officials say is safe, according to a January 2022 report on the testing process.
The state regulates the level of five specific PFAS in its drinking water — PFOA, PFOS, PFHxS, PFHpA and PFNA. Any combination greater than 20 parts per trillion is considered toxic.
Well No. 3, located just past the eastern edge of the former landfill, showed the highest total amount of PFAS among those tested: about 4,146 ppt. Well No. 108, which sits just to the west, had a concentration of about 1,680 ppt when tested.
At well No. 109-A, which is just north of well No. 3, PFAS contamination was measured at almost 640 ppt. A deeper well at the same location, No. 109-B, showed much lower contamination, though still more than double the state’s safe limit: about 45 ppt.
Just past the landfill’s western edge, at well No. 5, results showed contamination of nearly 460 ppt of PFAS.
A sixth well located on a separate property directly east of the landfill, No. 103, showed a concentration below the state’s toxic standard for PFAS.
Officials had planned to drill five more monitoring wells spread across properties north and east of the landfill, but were unable to because there was not enough soil on top of the bedrock in those areas, according to Kasey Kathan, an environmental analyst with the state’s solid waste management program.
Drought conditions in 2021 also delayed when officials could sample the wells they were able to drill.
Kathan, who wrote the May 23 letter to the South Hero Selectboard, said since the bedrock is so shallow, officials need to conduct more testing to determine whether the aquifer in that bedrock has been contaminated with PFAS, too.
“We want to make sure that we understand if it's moving into the potential water supply,” she said, “then we can move forward with figuring out how to protect people into the future.”
According to the January report, the monitoring well data suggests PFAS contamination in the landfill originates from “a small, localized area” near wells No. 3 and 108, which are along the closed facility’s eastern edge.
Moreover, the data suggests that PFAS appear to migrate largely toward the northwest, in the direction of well No. 5, the report states. It’s also possible that there is an additional PFAS source near well No. 5, according to the report.
In response to a question, Kathan said she wasn’t aware of recent progress toward figuring out what caused such high levels of PFAS at the landfill. One official had previously called the contamination there “really surprising.”
PFAS are used widely in manufacturing, and can also be found in a number of consumer products, including food packaging, nonstick cookware, cosmetics and water-resistant clothing.
The chemicals are “ubiquitous,” said David Carter, the South Hero Selectboard chair. “It's hard to pinpoint any particular source.”
Well No. 5 is located near the border of a property off Lavin Lane that Carter has previously described as “ripe and primed for growth,” since it has access to a septic system. South Hero does not have a municipal wastewater system, so new development can be contingent on access to a new or existing septic system.
The portion of that property closest to the landfill is zoned as “rural residential,” which per South Hero’s regulations, includes home and business uses that are at lower densities than the island town’s village centers.
One of the wells that officials had planned to drill, but couldn’t because of the shallow bedrock, would have been located on the Lavin Lane property.
Kathan said officials don't yet have enough information to say for sure whether the groundwater at that property, and others around the landfill, is at risk for PFAS contamination that’s migrating underground.
So far, officials have detected contamination only on the landfill’s property, she said. She noted that the landfill’s cover is still in good condition, which means it should continue to be effective at directing rainwater off the landfill site.
But if contamination is detected on neighboring properties, she said, officials could consider solutions such as reclassifying the groundwater — which would restrict the drilling of new wells for drinking water in the area.
Carter said the town, too, is waiting for further testing before drawing any conclusions about the impact of the contamination.
Officials have proposed drilling additional monitoring wells at the site, including wells that penetrate deeper into the bedrock. Kathan has also urged the town to consider developing a long-term monitoring system for the landfill’s eastern boundary.
“It’s just a matter of trying to get educated as to what's in there,” Carter said.
