DES: Saint‑Gobain demolition nearly complete; bottled water, POET installs and water‑main work continue

Andy Fuller, project manager in DES’s Hazardous Waste Remediation Bureau, updated the commission on the Saint‑Gobain Performance Plastics site in Merrimack on June 13, reporting that demolition of the former manufacturing facility is nearly complete, point‑of‑entry treatment systems have been installed at hundreds of properties, and DES has requested additional data and a revised remedial action addendum from Saint‑Gobain.

“As of June 6, the demolition of the former facility is nearly a 100% complete,” Fuller said, noting that fencing and cameras remain and that Saint‑Gobain is evaluating potential PFAS leaching from the concrete using EPA’s LEAF framework and simulated runoff testing.

Fuller said contractors Second Wind Water Systems and Culligan have installed point‑of‑entry treatment (POET) systems for residents in the consent‑decree area: DES identified approximately 831 eligible properties and reported 708 POET systems installed as of June 4. He reported ongoing periodic maintenance by contractors and that DES will review annual summary reports of installation and maintenance activity.

On municipal water connections, Fuller said design and construction continue in the Litchfield/Bedford/Londonderry/Merrimack areas; in one referenced neighborhood 25 of 26 properties had completed exterior service connections and interior water meter installs and bottled water service is being discontinued in those properties. Fuller said DES expects additional attachments to Saint‑Gobain’s earlier term sheets and anticipated receiving a further update (term sheet 26) in early July.

Fuller summarized the long‑term well monitoring program: Saint‑Gobain is operating under a groundwater management zone work plan that will generally result in about six samples from eligible properties by the end of 2026; Fuller said that, as of the June update, roughly 769 properties had been sampled under the long‑term monitoring effort and that sampling was being conducted at a pace (roughly 150–200 properties per month) to meet the planned schedule. He said about 77 additional properties were identified as exceeding ambient groundwater quality standards for PFOA and were offered bottled water after identification.

Fuller told the commission that Saint‑Gobain’s submitted remedial action plan and remedial addendum did not meet DES requirements and that DES provided a detailed deficiency letter last October. Saint‑Gobain intends to submit a supplemental investigation work plan to address data gaps identified by DES and to support a revised remedial addendum.

Fuller also raised a soil‑disposition issue: a nearby property at 702 Daniel Webster Highway submitted voluntary soil testing that found PFAS in soil excavated for development. The property owner generated a soil pile that could not be reused on site; DES requested that Saint‑Gobain address the disposition of that soil and said the final disposition had not been determined at the time of the update.

Commission members and residents raised requests for expanded off‑site sampling of creeks, brooks and public areas and for clearer public communication on where PFAS contamination has been found. Fuller said DES would consider revisiting off‑site data points and that soil‑management plans for disposition could be applied when similar situations arise. Fuller noted that projects triggering alteration of terrain or other state permits are relayed to the remediation bureau for review and that balanced‑site practices (keeping soils on site) remain a priority.

DES continues to require remedial reporting, periodic status submissions by Saint‑Gobain, and additional investigation work to support an updated remedial action plan; the agency said it will review and comment on any supplemental work plans submitted by the company.