DES: demolition complete at former Saint-Gobain site; hundreds of POET systems installed, more sampling and soil work planned

The New Hampshire Department of Environmental Services gave a detailed update on remediation and monitoring tied to the Saint-Gobain/CincoBain site, reporting building demolition is complete, point-of-entry treatment systems have been widely installed, and both municipal water connections and expanded sampling efforts are under way.

Andy Fuller, project manager in DES’s Hazardous Waste Remediation Bureau, told the commission the Air Resources Division is terminating the facility’s air permit and that CincoBain completed demolition of the former facility as of Sept. 24; fencing and cameras remain for security. DES said CincoBain will provide a final demolition/decommissioning report and separate results from a leaching study performed on the remaining concrete slab following EPA guidance; the leaching study results were expected to lag the decommissioning report by several months.

POET installations and municipal water connections

DES reported contractors have installed approximately 758 POET systems for properties inside the consent-decree outer boundary; about 716 of those are considered complete per system-monitoring criteria. Saint-Gobain is conducting periodic maintenance and carbon change-outs as required and submits monitoring reports; DES said it will continue reviewing the May system-monitoring report and provide comments.

Saint-Gobain has connected roughly 160 properties to municipal water since construction began (28 in Bedford, 71 in Litchfield, 13 in Londonderry, 48 in Merrimack). The company and towns continue negotiations and construction planning for additional connections and for new mains; Londonderry also received an $8 million Drinking Water Groundwater Trust Fund grant to support a larger municipal-water project in that area.

Well monitoring and unsampled properties

Under the groundwater-management monitoring work plan, Saint-Gobain has sampled nearly 1,400 eligible properties to date and continues sampling roughly 150–200 properties per month to meet a 2026 goal of six PFAS sample results per eligible property. DES said properties with results exceeding the New Hampshire ambient groundwater quality standards (AGQS) for PFOA are offered bottled water by Saint-Gobain; DES reported about 159 additional properties identified since January that exceed the state AGQS and were offered bottled water.

DES has also sampled properties inside the outer boundary that Saint-Gobain previously declined to sample; that DES sampling covered about 88 properties, and DES reported ~22% of those showed AGQS exceedances (and 70 exceeded the EPA MCL for PFOA). Saint-Gobain later proposed sampling additional previously unsampled areas in Bedford and Litchfield; DES approved the work plan with comments and said those properties will be sampled twice before February 2026.

Soil investigation, remedial plans and developer activity

DES told the commission it reviewed Saint-Gobain’s remedial investigation and remedial action plan submittals and found deficiencies under the applicable guidance (identified in DES correspondence). Saint-Gobain submitted a work plan for additional data collection, which DES approved; that field work is expected later this fall.

DES also described a developer-reported soil contamination case at 702 DW Highway—across the street from the former facility—where the developer has proposed to move excess contaminated soil onto an adjacent parcel, stabilize and seed it, and record an activity and use restriction on the deed. DES said it believes the contamination stems from releases from the former Saint-Gobain facility and has notified the company.

DES requested that Saint-Gobain submit a work plan by Nov. 7, 2025, to evaluate PFAS distribution in soil within the consent-decree outer boundary to support future soil-management guidance for development projects. Fuller said the results will refine understanding of PFAS distribution in soils from facility emissions and guide protective management as development proceeds.

Questions from commission members

Commissioners asked whether Saint-Gobain is responsible for spent carbon disposal from POET systems; DES staff confirmed Saint-Gobain is responsible for system maintenance and disposal and replacement of spent carbon where breakthrough occurs. Members also asked about the intersection of local municipal projects and contaminated-soil management; DES described recent project planning changes by the town of Merrimack that reduced anticipated excess soil generation for a bridge replacement project.

Ending

DES said additional data from the soil-distribution sampling and the leaching study will be forthcoming, and that DES will continue to review reports and work plans and to require corrective work where it deems the submissions incomplete.