The Environmental Protection Agency says it will review the safety of four New Hampshire Superfund sites in 2019.
This year's reviews, which happen every five years at federally managed toxic waste sites, will include the former Pease Air Force Base and three old industrial sites and dumps in southern New Hampshire.
All four sites had toxic chemicals removed from their soil and groundwater years ago.
This year, as part of the routine reviews, EPA New England site remediation director Bryan says they'll test the sites for newer “emerging” contaminants like PFAS, which weren't part of decades-old clean-up plans.
"If we find imminent problems at those sites as a result of those evaluations, we're really poised to take action to reduce any of the human health risks," he says.
The EPA is currently working to list two types of PFAS as official Superfund contaminants, which Olson says could help the agency get more money from polluters for future clean-ups.
PFAS contamination has been confirmed at some New Hampshire Superfunds, including Pease and the Coakley Landfill in Greenland.
The other three sites up for EPA review have gotten less attention in recent years, but they show the diversity of hazardous waste clean-up sites in New Hampshire and nationwide.
One is the Sylvester site on rural Gilson Road in Nashua. It's an old "sand borrow pit," where the EPA says a single polluter illegally dumped 800,000 gallons of toxic waste – including arsenic and organic solvents taken from a Massachusetts incinerator – decades ago.
The EPA says it put 1.2 billion gallons of groundwater through treatment at the site in the late 1980s and early 1990s, removing more than 90 percent of the contamination.
This year’s reviews also include a Londonderry site called Tinkham Garage, where the EPA cleaned up oil and septic wastes that contaminated groundwater in the 1970s.
The site has since been redeveloped with big box stores and a senior housing complex, but officials are still monitoring it for new signs of contamination.
In the past decade, they say they found the site had unsafe levels of 1,4-dioxane – known, like PFAS, as an “emerging contaminant” – which prompted installation of new water line connections for some neighbors.
The final site up for review this year is the former New Hampshire Plating Company in Merrimack, which contaminated groundwater with cyanide, metal and solvents dumped in unlined lagoons.
The site’s clean-up began in the 1990s and ended in 2006. The EPA says remaining contamination should naturally decrease to safe levels over the next several decades. In the meantime, they’re working with state officials to keep an eye on nearby wells.
Site remediation director Bryan Olson says these sites are all unique, like most Superfunds, but they have one thing in common.
“We're really never done at these sites,” he says. “We're always taking a look at them as time goes on.”
The upcoming reviews could also involve more engagement with neighbors, he says, especially if the EPA discovers problems that require an immediate response.
New Hampshire has approximately 22 active or pending Superfund sites total.
Many are old landfills and industrial sites, and more than half are in Rockingham and Hillsborough counties.