Saint-Gobain, the French manufacturing company that operated a facility widely blamed for contaminating water supplies in southern New Hampshire, has finished demolishing its building in Merrimack.
All that remains on the site is a massive concrete pad, the floor of a building that was once several stories high and the size of a few football fields.
But the company still has not finalized a remediation plan for the site, which state regulators say is heavily contaminated with PFAS chemicals. Those man-made chemicals, known as forever chemicals, resist degradation in the environment.
New Hampshire regulators have denied Saint-Gobain’s plans for remediation thus far. The company has proposed “institutional controls” and “natural attenuation” — options that include no active cleanup, but limit the use of the site going forward and require the company to monitor contamination as the chemicals degrade over time.
A Saint-Gobain spokesperson said in an email that the company will continue to work closely with state regulators on remediation.
“Saint-Gobain’s proposed remedial action plan aligns with appropriate industry and environmental practices,” the company said.
Jeffrey Martz, the head of the hazardous waste remediation bureau at the New Hampshire Department of Environmental Services, said state regulators want to see the company significantly reduce the contamination on site.
The concentrations of PFAS in groundwater at the former facility are much higher than levels in water in surrounding communities, Martz said. In some monitoring wells on site, levels are in the tens of thousands of parts per trillion, while wells outside of the site are in the hundreds.
The contaminated groundwater at the site flows towards a brook that feeds into the Merrimack River, which supplies drinking water for several communities.
“A few miles downstream from the facility, there's a public water supply intake,” Martz said. “So we want to see the mass of PFAS that discharges to surface water diminished.”
There are several ways Saint-Gobain could reduce PFAS concentrations, he said. They could dig up the most contaminated soils and remove them from the site. They could inject the site with chemicals that bind to PFAS to keep them from moving around in groundwater and in the aquifer. They could contain groundwater in a series of underground pumping wells that lower the water table and contain the flow.
“There's a lot of research going on across the country and even globally to address this recognized growing problem,” Martz said. “We put it back on the responsible party to look at the emerging science and evaluate options and present those.”
A representative from Saint-Gobain said the company continues to believe letting the chemicals degrade in the environment on their own and limiting the use of the site — the proposed remediation plans state regulators have rejected — are the best way forward. But they are preparing a plan to collect additional data and look at other options.
State regulators are expecting Saint-Gobain to propose its work plan for investigating the site in the next couple of weeks. The investigation, which may help identify remediation strategies, would likely stretch through the fall.
