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In May 2021, state officials discovered that an underdrain carrying groundwater away from the state’s only landfill — which empties into nearby water bodies — was contaminated with PFAS, a class of chemicals that are harmful to human health. 

Casella, the company that owns the Coventry landfill, has submitted a plan, in the form of an amendment to their operating permit, to address the contamination. Members of the public are able to weigh in until Sept. 2. 

The underdrain carries between 4,000 and 13,000 gallons of groundwater per day from beneath the landfill and away from the facility toward the Black River, which drains into Lake Memphremagog, a drinking water source for more than 175,000 Canadians.

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At a Thursday night meeting, Coventry residents and members of the group Don’t Undermine Memphremagog’s Purity, or DUMP, asked questions about the impacts of PFAS in the groundwater and the effectiveness of Casella’s proposed project. 

This permit amendment is separate from another PFAS-related pilot project Casella is working on that would take PFAS out of its leachate, the liquid waste from the landfill. Leachate is currently treated at the Montpelier wastewater treatment facility before being discharged into the Winooski River, which eventually empties into Lake Champlain. The wastewater treatment facility doesn’t take PFAS out of the leachate. 

State officials have been sorting through a bevy of public comments about the pilot project, and haven’t yet finalized that permit. 

The water coming from the underdrain — at issue during Thursday night’s meeting — is treated differently than leachate because the water does not filter through the landfill, but rather comes from groundwater below the double liner of the facility, Kasey Kathan, an environmental analyst with the state’s solid waste program, told attendees of the meeting.

State officials with the Department of Environmental Conservation sample the landfill and its discharge points for PFAS twice a year, and conduct more frequent monitoring for other materials, according to Dennis Fekert, with the state’s solid waste program. 

Samples from May 2021 from the underdrain contained 73 parts per trillion of the five components of PFAS regulated in Vermont. While Vermont has not set a regulatory standard for PFAS in surface water, its current limit for PFAS in drinking water is 20 parts per trillion. 

Casella then installed and began monitoring a groundwater well to determine whether surrounding groundwater was impacted by the contamination. The state’s groundwater “preventative action level” — the level at which the state suggests taking action to prevent further contamination of PFAS — was 10 parts per trillion at the time. When samples in the well showed 11 parts per trillion, the state asked Casella to install a treatment system. 

The preventative action level has since been lowered to two parts per trillion, Kathan said. 

Recently, the federal Environmental Protection Agency issued a health advisory stating that PFAS limits should be drastically lower than they are — close to zero — in both federal and state regulation. The state is currently evaluating how to move forward with that federal guidance. 

State officials are not sure where the PFAS contamination is coming from, though they think it could be from an older part of the landfill, which does not have the double liner system that protects leachate in the newer part of the facility from seeping into the groundwater. 

Casella plans to install a granulated activated carbon, or “GAC,” system to remove PFAS from the discharge water. The water will flow from the underdrain into canisters containing the carbon treatment, and from there, the water will flow downslope out of the containers, Kathan said.

“Granulated activated carbon is capable of removing, to the lab detection limits, all of the PFAS that are capable of being analyzed currently,” Kathan said. 

Attendees of the meeting asked state officials why Casella chose to use the GAC system rather than other available technologies. Kathan said the state approved Casella’s choice because it met their regulatory requirements. 

“In this case, this is what the landfill has proposed to us,” she said. “We have drafted the certification in a way that allows us to monitor it and make sure that it is achieving those regulatory standards, and believe it is sufficient.”Members of the public can comment on the permit amendment on the state’s Environmental Notice Bulletin web page by searching the permit number, OL510-2022-2.

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Emma Cotton is a Report for America corps member who covers the environment, climate change, energy and agriculture. Previously, she covered Rutland and Bennington counties for VTDigger, wrote for the Addison Independent and served as assistant editor of Vermont Sports and VT Ski + Ride magazines. Emma studied marine science and journalism at Eckerd College in St. Petersburg, Florida.

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