Barnstable County updates public on PFAS plume, begins full-scale carbon barrier after successful pilot

Barnstable County and consultants gave residents an update on ongoing investigations and remedial work at the former municipal fire training site in Barnstable on Oct. 12, 2025, and confirmed a full-scale permeable reactive barrier (PRB) is being installed after a pilot test sharply reduced groundwater PFAS concentrations.

The county’s Paul Rosala, Barnstable County assets and infrastructure manager, opened the meeting and said the session was “the former municipal fire training site, PFAS release response public update.” John Paquin, principal hydrogeologist with GZA GeoEnvironmental, told attendees the project is being executed under the requirements of the Massachusetts Contingency Plan. “We’re focused on complying with the requirements of the Massachusetts contingency plan,” Paquin said.

The update summarized recent field work, new groundwater monitoring, ecological sampling and a PRB pilot test that GZA said produced rapid declines in PFAS in downgradient monitoring wells. GZA reported adding 16 multilevel monitoring wells to fill data gaps, instrumenting ponds to measure groundwater–surface water interaction, collecting sediment, insect and upcoming fish samples for an ecological risk assessment, and performing PFAS “forensics” to compare chemical fingerprints across the site and neighboring properties.

Why this matters: the plume of regulated PFAS (PFAS-6) overlaps shallow and intermediate groundwater between the training site and municipal supply wells known as the…