DES reports demolition progress, POET installations and expanded sampling at Saint‑Gobain site; long‑term monitoring plan set

The New Hampshire Department of Environmental Services provided a March 14 update on Saint‑Gobain site activities, water‑system remedies and long‑term monitoring plans.

DES said demolition of portions of the Saint‑Gobain facility is underway: demolition permits for the lower bay and ancillary structures have been completed and, as of March, about half of the high bay portion of the building had been dismantled. DES said areas of the building substantially affected by PFAS will be sent to out‑of‑state hazardous‑waste disposal and that structural steel is slated for recycling. The company reported scarification of concrete floors in contaminated areas (removal of a shallow surface layer in targeted areas) and told DES it expects to remove the above‑ground structure in 2025, leaving the concrete slab and foundation in place.

DES reported progress on point‑of‑entry treatment (POET) systems and connections: about 690 POET systems have been installed in impacted towns and roughly 669 are considered complete after confirmation testing. A Saint‑Gobain rebate program for POET systems has processed reimbursement letters and issued payments to eligible properties. For waterline construction, DES said work in Litchfield’s Hillcrest Road area is substantially complete; 55 residences there have been disconnected from private wells and are now on the utility. In the service areas in Bedford and Merrimack, exterior service lines and meters have been installed at many properties, and additional interior connections and restorations are scheduled for spring when roadways reopen to construction traffic.

DES described its sampling and monitoring work. The company has submitted and revised a groundwater monitoring zone work plan; DES approved the revised plan with comments in January 2025. Under the revised plan, Saint‑Gobain is to provide six PFAS sample results for each eligible property by the end of 2026 so that trend information will be available. DES also reported that it conducted sampling of properties within the consent‑decree outer boundary where Saint‑Gobain declined to sample; DES sampled about 86 residences between March 2024 and March 2025 and received results for all of them. DES said about 22% of those sampled exhibited exceedances of the New Hampshire ambient groundwater quality standard and about 70% exceeded the federal EPA drinking‑water MCL (as referenced in DES remarks). DES said the company plans to resample approximately 200 properties per month under the revised work plan and will submit bimonthly status reports to DES.

DES also described the status of alternate‑water and rebate programs, noting that Saint‑Gobain had provided bottled water or POETs to many properties. Bottled‑water delivery in one Litchfield area will end in April after eligible connections are completed. On the site investigation and remedy plan, DES said Saint‑Gobain is preparing a WRAP addendum to evaluate additional remedial alternatives and that a work plan to address data gaps is expected in the second quarter of 2025.

Commissioners asked about risks from recycling structural steel and about leaving the foundation in place. DES responded that steel is typically processed at high heat during recycling and is not expected to spread PFAS; DES also said the foundation is a deep, reinforced structure and that removing it may not materially change groundwater risk, noting that removal must be weighed against likely higher‑priority remedies such as soil removal and groundwater pump‑and‑treat options.

Ending: DES said it will continue periodic site visits and work with Saint‑Gobain on demolition, sampling and the WRAP addendum, and will report progress to the commission at future meetings.