DES outlines monitoring progress and defends site‑specific approach to PFAS‑contaminated soils

The New Hampshire Department of Environmental Services told the Legislative Study Commission on Jan. 9 that remediation work tied to the Saint Gobain PFAS releases is progressing but that some soil‑management choices will be site‑specific, not uniform removals. "We expect to receive [the decommissioning] report at the end of this month," DES representative Mike Clark said, adding that written notes distributed to the commission supply additional detail.

DES said 805 point‑of‑entry treatment (POET) systems had been installed as of Jan. 7, and 774 of those systems have completed verification and are considered officially complete. The company performing remediation has sampled approximately 1,529 properties eligible under its groundwater management‑zone work plan; DES said properties that exceed the applicable groundwater quality standard for PFOA have been offered bottled water and are tracked in alternate water status reports.

The department described a multi‑step process for remedial planning: prior remedial action plan submissions and addenda were found deficient, the company has identified data gaps, and supplemental investigations (temporary monitoring wells and soil sampling in December) are under way to support a revised remedial addendum expected this spring. DES said it approved a long‑term monitoring work plan and that the plan aims to produce multiple PFAS sampling events per eligible property so trends can be assessed over time.

A central point of contention was how contaminated soils are handled when developers generate excess material. Clark described a recent case at 702 Daniel Webster Highway in which a developer acquired an adjacent parcel to manage excess soils on‑site, stabilized and covered the material, and recorded—or is preparing to record—an activity and use restriction on the receiving parcel. "We accepted that as a reasonable solution for this particular development project," Clark said, explaining that complete excavation and off‑site disposal for all affected soils is not practicable in a study area as large as the one around the Saint Gobain facility. He emphasized DES's priority is preventing human exposure, particularly through drinking water, while the agency works to refine soil‑management guidance.

Commission member Lorraine criticized the approach as inadequate and said the site should be treated more aggressively. "It should be a Superfund site," she said, and warned that mounds of contaminated soil that remain in place—even if covered—may continue to pose hazards. Clark replied that DES will continue to press the company to meet its responsibilities for alternate drinking water and that the agency is seeking a more robust soil‑sampling program to inform statewide soil‑management standards.

DES also acknowledged technical uncertainty about long‑term groundwater trends and said more time series data are needed before it can determine whether concentrations have peaked or will continue to rise. The department said it would share visuals and status reports with the commission and that it will forward promising remediation‑technology studies to consultants working on large‑scale remedies.

The commission pressed DES to provide a revised soil‑sampling work plan (for Bedford, Merrimack and Litchfield) and to clarify when a remedial addendum might be ready; DES replied it anticipated receiving the revised work plan by March and a remedial addendum this spring. The department said it will continue to prioritize actions that reduce exposure to drinking water while collecting the additional soil and groundwater data needed to guide broader policy.