MERRIMACK — Local residents say they do not trust that requirements in a newly proposed air permit for Saint-Gobain Performance Plastics will fully eliminate contaminated emissions from its smokestacks.
Although the New Hampshire Department of Environmental Services required that the Saint-Gobain plant investigate and apply for a permit to install air pollution controls on its Merrimack facility, residents said during a public hearing on Tuesday that the draft air permit will not do enough, adding they do not want to settle.
“Our community has endured a lot of harm. We are ground zero for PFAS,” said Laurene Allen of Merrimack Citizens for Clean Water.
Allen said 190 PFAS (per- and polyfluoroalkyl substances) compounds have been identified as being released from the stacks at Saint-Gobain, yet New Hampshire legislation only addresses four of those compounds. While the air permit is designed to destroy all of them, Allen said, “if feels like it is a little bit of a leap of trust.”
According to Catherine Beahm of the Air Resources Division of NHDES, Saint-Gobain is proposing in its air permit to utilize a three-chamber regenerative thermal oxidizer to eliminate PFAS compounds from being emitted into the air. Beahm said this process would result in 90 percent control efficiency based on PFAS deposition modeling.
The cost of the regenerative thermal oxidizer is estimated at about $3 million.
Town officials argue that 90 percent control efficiency is not enough, and is a less than perfect solution. Barbara Healey, town councilor, said the level of destructive effectiveness should be closer to 95 to 99 percent.
“My thought would be that, at a minimum, we would expect to see that,” she said.
Geoff Daly of Nashua stressed that Saint-Gobain has had three years to finalize an air permit. PFOA contamination was discovered at two faucets at Saint-Gobain more than three years ago, resulting in hundreds of homes receiving bottled water and new public water extensions since the contamination was discovered in neighborhoods in Merrimack, Litchfield and Bedford that surround the plant.
“Saint-Gobain has not considered the latest technology, which is plasma oxidation,” said Daly, maintaining that process would destroy everything.
Several PFAS compounds were previously detected in all nine of the stack residue samples collected at the Saint-Gobain facility. The plant initially made some improvements to one of its smokestacks in an effort to decrease the amount of residual contaminants being emitted into the air.
And last year, Saint-Gobain began piloting a treatment system for its air emissions at the facility, which was also designed to determine whether next-generation compounds were existing through the plant’s smokestacks; that pilot was not as effective as hoped, according to Beahm.
“This is a complicated permit. There are a lot of people interested in it,” said Beahm.
She did acknowledge, however, that the proposed regenerative thermal oxidizer process would result in higher hydrogen fluoride levels, but that those emissions would not be high enough to exceed ambient air limits.
If the air permit is issued and the regenerative thermal oxidizer is implemented, Beahm said Saint-Gobain would be required to stack test and verify emissions to make sure they comply with standards.
“We have a situation where our air, our soil and our water has been polluted,” said Peter Albert, town councilor, maintaining DES should be approving the most stringent air permit possible and should be striving for 99 percent PFAS reduction.