LEBANON — In an increasingly common discovery, groundwater at the Lebanon airport was confirmed to be contaminated with the toxic forever chemicals known as PFAS.
The question now is the extent of the pollution and the public health risk.
Environmental consultants collected two groundwater samples at the airport in February that contained multiple kinds of PFAS in amounts above state and federal standards.
PFAS are a group of thousands of manufactured chemicals that can be present in water, soil, air and food, take years to break down and can build up in people, animals and the environment, earning the moniker “forever chemicals.” Exposure to PFAS has been linked to health effects including reproductive problems, developmental delays in children and high cancer risk, according to the U.S. Environmental Protection Agency.
The EPA and state of New Hampshire consider PFAS unsafe at concentrations of 4.0 – 18 nanograms per liter of water, depending on the specific chemical compound. One nanogram per liter of water is about the same as a drop of water in 20 Olympic-sized swimming pools, according to Penn State Extension.
The City Council will hold a public hearing Wednesday and consider allocating $104,500 to a state-mandated investigation to determine the full extent of the contamination.
The study will also look into the source of the chemicals and whether more research or remediation will be necessary, according to a May 1 letter to the city from the state Department of Environmental Services, or DES.
“While it’s always a shock to find any amount of PFAS in our own backyard, PFAS contamination at airports is quite common,” said Megan Romano, an associate professor of epidemiology at Dartmouth College who has studied PFAS in New England.
A common source of PFAS contamination is aqueous film-forming foam that is used to suppress fires. The Federal Aviation Administration required airports to use the firefighting foam for many years, Romano said.
The foam was previously stored at a facility at the Lebanon airport near the contaminated well, according to the letter from DES. Another possible source, DES wrote, was a 2012 plane crash. After the crash, the department recorded that foam residue was found in puddles around the site, but the exact type of foam used was not logged.
Consultants from government contractor Booz Allen Hamilton collected the contaminated groundwater samples in February in connection with the construction of a new air traffic control tower at the airport, according to a report from the company.
The consultants completed a “phase 1” environmental assessment at the airport in 2024 and recommended testing for PFAS because of the historic use and storage of the firefighting foam, according to the report.
Engineers collected the groundwater north of the airport terminal and parking lot at the planned site of the new tower.
The contaminated water included concentrations of PFAS that were only slightly above state and federal standards, which Romano said is a good thing.
“Of course we would prefer that it was less than that, but it’s helpful to know that it’s only a little bit higher,” Romano explained.
The groundwater sample tested positive for levels of three kinds of PFAS above federal standards: perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS) and perfluorononanoic acid (PFNA). The highest leves were PFOA, which was found to be 63 nanograms per liter higher than the federal standard of 4.
The PFOS came in at 4.2 compared to 4, while PFNA registered at 12, compared to federal standard of 10.
All three are considered “legacy PFAS,” said Romano.
“These are older PFAS that have been in use for a longer amount of time, and so we do know a little bit more about the health effects of those” than of newer compounds that scientists are still learning more about, she explained.
As for environmental concerns, the airport property “slopes very gently toward the Connecticut River to the west and the Mascoma River to the north,” according to the Booz Hamilton report. Groundwater from the airport flows toward both rivers.
While the Connecticut River is not used to supply drinking water to Lebanon, any PFAS contamination could make it unsafe to eat fish from the river, Romano said. She recommends that people who fish frequently keep an eye out for fish consumption advisories issued by DES.
The silver lining, if there is one, is that other contaminated sites along the Connecticut River have already triggered the water monitoring process, Romano added.
Any drinking water supplied by the city of Lebanon is also going to be treated for PFAS and other contaminants, Romano noted. She recommends private well users have their water source tested for PFAS and noted that the state offers financial assistance for homeowners who learn their well has PFAS.
Airport Manager Carl Gross said the state has never before mandated a full study of PFAS contamination at the airport. In 2018, he noted, the state sampled a well that supplies buildings at the airport and found elevated levels of a different kind of PFAS.
Gross said Monday he does not yet know what further investigation or cleanup might cost, but expects the study to help answer those questions.
After receiving the letter from DES, Gross reached out to multiple engineering firms to request proposals for the project, according to materials prepared for Wednesday’s meeting. The lowest bid came from Bedford, NH-based Sanborn Head & Associates.
The $104,500 would be taken from the airport fund balance, which comes from airport revenues, not property taxes. If approved, the airport will be left with about $800,000 in the fund.
The Federal Air and Aviation Administration is in charge of the air traffic control tower project. The federal government allocated $1.105 billion in 2022 to replace air traffic control towers around the country.
The current tower in Lebanon was built in 1974, said Gross, and the airport is one of 31 airports around the country where the FAA is working. Construction on the tower is expected to start in 2028 and will take about a year.
The Lebanon City Council is scheduled to meet at 6 p.m. Wednesday in Council Chambers at City Hall.
