DES: Saint‑Gobain demolition continues; 695 home treatment systems installed, waterline work advancing

Mike Wimsat, service director of the Waste Management Division at the Department of Environmental Services, told the commission on April 11 that demolition at the Saint‑Gobain facility is continuing and the company "anticipate[s] completing all the demolition activities during this calendar year." Wimsat gave a detailed progress report on household water remedies, infrastructure work and monitoring tied to PFAS contamination from the site.

The update matters because the work affects drinking water access and long‑term remedial decisions for properties in the consent‑decree area. DES staff described how demolition, household treatment installations and expanded well sampling fit into the state’s efforts to limit exposure and collect data needed for future cleanup work.

Wimsat said demolition of the facility’s low‑bay and ancillary structures is complete; a high‑bay demolition permit was issued in January, and as of April 9 about one third of the high bay had been removed. Steel will be recycled and materials judged to be significantly contaminated by PFAS are being sent to out‑of‑state licensed hazardous‑waste landfills, he reported. He said the company has been scarifying concrete floors where contamination was found, sampling the remaining foundation materials, and will determine whether further removal is necessary.

On residential remedies, DES reported 695 point‑of‑entry treatment (POET) systems have been installed since the program began; 670 of those have completed post‑installation verification and are considered functionally complete though they will continue to receive routine operation and maintenance. Wimsat said the company ran a POET rebate program for properties that installed treatment before POETs were offered; about 35 reimbursement requests were processed and payments issued.

DES staff described public‑water connections underway in Litchfield, Bedford and Merrimack. In the Hillcrest Road extension area in Litchfield, construction is substantially complete and 55 residences have been disconnected from private wells and connected to the municipal system (Pennichuck). The utility told DES that 32 properties declined full connection, 14 requested water line extensions to the curb stop without interior connection, and 10 properties did not respond to notices.

In Bedford and Merrimack contractors installed service connections in 2024; of 33 eligible properties in one area, 30 returned applications and exterior service lines and meters have been installed at most of those locations. In the Merrimack Wildcat/Bridal Lane area the water main extension and testing were complete and 21 of 26 eligible properties had meters installed. By contrast, the town of Londonderry remains largely unaddressed because of the larger number of properties that require new mains; Wimsat said only about 3.6% of Londonderry properties identified for waterline remedy are complete to date.

On sampling and monitoring, DES reported Saint‑Gobain resubmitted a groundwater management‑zone work plan and the agency approved that plan with comments on Jan. 15. Under the revised work plan the company will generate at least six PFAS sample results per eligible property by the end of 2026; as of April 2 Saint‑Gobain had resampled approximately 350 eligible properties and expects to sample 50 to 200 properties per month. DES said roughly 35 additional properties were identified as exceeding the ambient groundwater quality standard for PFOA during the resampling and have been offered bottled water by the company.

Wimsat told commissioners DES has not accepted Saint‑Gobain’s original remedial action plan; the company has identified data gaps and is preparing a supplemental investigation work plan expected in the second quarter of 2025 (April–June). DES staff will review that work plan and continue periodic site visits and monitoring while demolition and investigation continue.

Commission members asked several operational questions: where the facility’s regenerative thermal oxidizer (RTO) ended up (Wimsat said his understanding is it was disassembled for scrap but he would confirm with the inspector Andy), and whether scrap steel recipients are informed of PFAS contamination (Wimsat said contaminated non‑steel debris has been sent to licensed hazardous‑waste landfills; typical scrap steel shipments go to scrap yards and DES has not specifically required that recyclers be notified of PFAS in the steel shipments).

DES provided a status snapshot it will include in the minutes with town‑by‑town completion percentages: POET implementation is over 90% complete overall (Merrimack lower because of small numbers; Londonderry about 96% POET completion), while waterline remedies vary by town (Merrimack roughly 67–69% complete, Litchfield about 90–97%, Bedford about 77%, Londonderry about 3.6%). Wimsat said monthly status reports and links to supporting documents will be provided to the clerk for inclusion in future minutes.

Next steps DES identified include receipt and review of the supplemental remedial investigation work plan in Q2 2025, continued bimonthly sampling reports under the revised groundwater work plan, and continued demolition oversight. The commission postponed a separate discussion of soil contamination until its May 9 meeting so a soil program official (Jeff Martz) can attend and provide updated information.