Barnstable County plans reactive barrier to intercept PFAS plume from former Hyannis fire training site

Barnstable County consultants presented plans to install a permeable reactive barrier (PRB) using colloidal activated carbon at the former Hyannis fire training site in central Barnstable to intercept PFAS migrating toward Mary Dunn Pond and nearby public drinking water wells. The team said full‑scale injections are scheduled to begin in mid‑July and are expected to take about 12 weeks to complete, subject to permitting.

The project aims to reduce the volume of PFAS reaching downgradient receptors so the Hyannis Water District’s wellhead treatment systems require less intensive filtration. John Paquin of GZA, a presenter on the call, described the contaminants as “the so‑called forever chemicals… PFAS,” and showed groundwater contours indicating flow from the site to Flint Rock Pond and southeast toward Mary Dunn Pond and the Mary Dunn public wells (identified in presentation materials as MD‑12 and MD‑3).

Consultants emphasized that the county already took two actions: stopping water‑based firefighting training in 2019 and installing a site cap to limit precipitation infiltration. The PRB is the horizontal component of the county’s remedial approach. Dan…