Saint‑Gobain begins phased demolition; DES says contaminated debris will be removed and some concrete scarified

Andy (Department of Environmental Services, Air Resources and site oversight) updated the commission on Feb. 14 that Saint‑Gobain completed cessation of manufacturing in 2023 and began phased demolition in late 2024; state staff have been receiving periodic progress reports.

“Initial demolition pertained to the low‑bay portion of the building,” Andy said. He reported crews removed interior overhead gantry cranes and that the work planned for 2025 includes dismantling the high‑bay portion in sections. He said structural steel will be removed for scrap recycling, and portions of demolition debris that are “significantly impacted by PFAS contamination” will be shipped to out‑of‑state hazardous waste disposal facilities.

Concrete and scarification: DES staff described a site practice of scarifying concrete floor surfaces — mechanically removing a thin surface layer — to reduce surficial contamination prior to exterior demolition. Andy told the commission the contractor has been scarifying roughly an eighth to a half‑inch in affected areas and collecting the removed material for containerized disposal.

Sampling and remedial planning: DES said Saint‑Gobain hired Ramboll to support closure activities and has provided interim reports. The department reviewed a remedial action plan (RAP) and asked for additional detail; DES staff said a revised RAP addendum did not fully meet regulatory requirements and that Saint‑Gobain has proposed supplemental investigation work to fill data gaps. DES expects a work plan for supplemental investigation and further remedial alternatives in the coming months.

Point‑of‑entry treatment and alternate water: Andy said contractors (Second Wind Water Systems and Culligan) had installed about 690 point‑of‑entry treatment systems for affected residences through early 2025 and have been conducting periodic maintenance under a work plan. He said Saint‑Gobain continues to provide bottled water and temporary/permanent alternate water supplies inside the consent‑decree area as appropriate.

Municipal water extensions and residential sampling: DES reported construction of water main extensions in Litchfield, Bedford, Londonderry and Merrimack with service connections ongoing; in some areas final restoration is scheduled for spring 2025. On residential sampling, DES told the commission it identified 3,868 properties eligible for sampling, of which 2,578 well samples have been collected and 1,211 second samples recorded; 1,183 properties have been offered bottled water under the program as of Jan. 29, 2025.

Permits and air emissions: Andy said Saint‑Gobain submitted a request to terminate its air discharge permit; DES expects termination once reporting and fee obligations are satisfied. Andy said no ongoing stack testing is occurring because manufacturing ceased in 2023.

Community concerns and next steps: Commissioners and local participants asked whether Saint‑Gobain could sell the property after demolition and how concrete left in place may affect future groundwater. Andy said Saint‑Gobain would retain environmental liability even if the property is sold, and that DES is monitoring how the remaining foundation and scarified surfaces may affect site runoff and the conceptual site model. DES said it will continue frequent contact with the company, perform site visits, review remedial submittals and oversee residential well monitoring and alternate water programs.

What’s next: DES expects additional RAP information and a supplemental investigation work plan from Saint‑Gobain this year; the department noted it will review those submittals and adjust oversight accordingly.