Montpelier Water Resources Recovery Facility. Photo by Lauren Milideo/The Bridge
This story by John Dillon was first published at The Bridge on November 7.
The city of Montpelier has shelved an ambitious but expensive plan to upgrade its wastewater treatment plant with technology that would remove dangerous chemicals from sewage sludge “forever.”
Faced with cost estimates that had risen from $16.4 million to $32.4 million, the city council opted Oct. 23 to proceed with only the preliminary phase of the project. This option allows the public works department to install equipment to dry the sludge, reduce odors in the facility and make other improvements. But council members postponed the plan for more advanced equipment that would superheat the waste to virtually eliminate levels of per- and polyfluoroalkyl substances (PFAS).
The option chosen by the council will cost approximately $21 million. Mayor Jack McCullough noted that the city could install the more expensive technology at a later date. But with another bond vote needed to cover rising costs — and the city’s budget already under pressure — delaying the project is “almost a no-brainer,” McCullough said.
The decision still leaves the city with a PFAS problem. The sewage treatment plant is the only one in the state to accept PFAS-contaminated leachate from the Casella landfill in Coventry.
Public Works Director Kurt Motyka said an experimental pretreatment system installed in Coventry reduced the levels of five different PFAS compounds in the leachate by 89% to 94%. But because the chemicals are ubiquitous in a range of consumer products, some PFAS still end up in sewage sludge even without the Casella leachate.
Currently, the city sends its sludge to the Coventry landfill, but pays a reduced rate because it also accepts Casella leachate. Motyka told the city council that without the more advanced treatment, the city’s ability to remove the sludge remains limited.
The PFAS group of chemicals was used in a range of consumer products, from cosmetics to carpets and Teflon non-stick cookware. State and federal regulators have taken steps in recent years to limit the use of PFAS as new evidence emerges that they are found virtually everywhere in the environment.
A 2019 study for the state of Vermont found minute levels of PFAS in every soil sample tested at 66 locations across the state. Researchers think these background levels are likely due to atmospheric deposition, because chemicals released by industry are carried long distances by wind.
The compounds are known as ‘forever chemicals’ because they break down very slowly in the environment. They are linked to a number of health problems, including cancer, low birth weight, high cholesterol and damage to the immune system.
“This stuff is so ubiquitous,” said John Brabant, a former environmental regulator at the Agency of Natural Resources who now works with the advocacy group Vermonters for a Clean Environment.
Sewage sludge is a major source of PFAS contamination. The sludge – known in the waste industry as ‘biosolids’ – was routinely applied as fertilizer to agricultural fields. The state of Maine has banned the land application of sewage sludge after fields and farms were contaminated. Vermont still allows the application of sludge to land, but has strictly limited the practice. Massachusetts and New Hampshire are also considering banning the application of sludge to land.
Since 2019, the Vermont Department of Environmental Conservation has required testing of soils to which sludge has been applied, as well as groundwater near the sites. The state found that PFAS levels exceeded state standards in 31 of 138, or 23%, of groundwater monitoring wells. But officials say so far no drinking water supply has been affected by PFAS from sludge applied to land.
Montpelier’s sludge is not spread over the fields. Public Works Director Motyka said the first phase of the project to dry the sludge would reduce disposal costs because the volume of the material would be reduced. Drying the sludge could also give the city other options, such as spreading the sludge on land, he said.
“By just running the dryer without doing the secondary advanced thermal treatment – which is the part that breaks down the PFAS – we would have the potential to apply the sludge to the land. But for that we still have to go through the permitting process,” Motyka told the council.
Whether the city would get approval to spread the sludge without the system that breaks down the PFAS is another question. The state has established regulations that limit land use to locations where the sludge applied does not exceed background levels in the soil.
“Virtually all of our sludge will contain PFAS,” said Eamon Twohig, manager of Vermont’s Residuals and Emerging Contaminants Program. “The goal is to basically keep soil levels in Vermont at the – quote unquote – ‘background’ level and not to increase those levels.”
The advanced thermal treatment breaks the carbon bonds in the PFAS chemicals and reduces PFAS to undetectable levels, Motyka said. The state had promised a $2 million grant to pay for the technology. But Motyka told the council that much more state funding was needed to help the city address what is essentially a statewide issue. He noted that the city’s wastewater plant treats two-thirds of all of Vermont’s septage — which is waste pumped from septic tanks — as well as septage from out-of-state sources.
“It’s a regional problem,” he says. “We are trying to solve a PFAS problem that extends well beyond Montpelier, so I hope there is an opportunity to get a lot more grant funding to make this project more feasible.”
Leave a Reply