DES adopts PFAS soil standards; asks Saint‑Gobain to address excess soil and continues site work

The New Hampshire Department of Environmental Services has finalized soil remediation standards (SRS) for regulated PFAS compounds and has begun applying the new standards to sites tied to the Saint‑Gobain Performance Plastics contamination in Merrimack, DES staff told the House study commission.

Jeff Martz, administrator of DES’s Hazardous Waste Remediation Bureau, said state statute RSA 45‑H:13 (enacted July 22, 2022) directed rulemaking that led to PFAS soil remediation standards effective December 2024. Martz described the multi‑factor methodology DES used: direct‑contact risk‑based values, leaching‑based values to protect vulnerable groundwater, natural background screening values, laboratory quantitation limits, and a ceiling concentration where applicable.

Why it matters: the new SRS establish enforceable soil thresholds that aim to prevent further leaching of PFAS from soil to drinking water. DES staff said the rules change how the department evaluates where soil must be removed, contained or otherwise managed during redevelopment and site work.

Martz summarized the USGS‑DES statewide soil survey that informed the rulemaking: DES and the USGS collected shallow (0–6 inch) samples in 100 grid cells across…