County Details PFAS Cleanup at Former Fire‑Training Site; Plans Full‑Scale Reactive Barrier

Barnstable County officials and consultant GZA briefed the Assembly of Delegates July 2 on long‑running PFAS contamination at the former municipal fire‑training facility in Hyannis and described near‑term cleanup steps, a schedule and funding context.

Paul Rosala, the county’s assets and infrastructure manager, said the county owns the roughly five‑acre site where aqueous film‑forming foam (AFFF) was used during training over several decades and that PFAS from those exercises contaminated soils and groundwater and has impacted municipal drinking wells down gradient. Rosala said the county does not have records of the foam volumes used because the site was used by multiple local fire departments and the county “did not provide foam.”

GZA Principal John Paquin said the county and consultants have compiled decades of historical data, installed 16 additional multi‑level monitoring wells, and analyzed groundwater flow to distinguish the fire‑training plume from other local PFAS sources, including airport and wastewater‑treatment‑plant releases. Paquin described the planned remedy: a full‑scale permeable reactive barrier (PRB) consisting of injected activated carbon placed along the downgradient inside of the county property to sorb PFAS and limit further off‑site migration. Paquin said a small pilot PRB installed late last year produced strong early results, including a drop from measurable concentrations at the downgradient monitoring points to nondetectable levels in the areas tested.

Work schedule and costs: Paquin said the full‑scale PRB injection is scheduled to begin the week of July 14 and is expected to take roughly three months to install. The county has removed more than 200 tons of hot‑spot soil and paved (capped) the site to reduce infiltration. The county currently operates a groundwater pump‑and‑treat system that draws impacted groundwater to a carbon treatment unit and then discharges treated water back to the aquifer; consultants said pump‑and‑treat is expensive and that the PRB is intended as a more efficient, passive approach to reduce long‑term migration and treatment costs.

Liability and funding: County staff said the county has an earlier settlement with Hyannis (Hyannis Water District) that obligates the county to share some operation and maintenance costs for affected wells; the county has also allocated ARPA funds and retained outside counsel and consultants for remediation and potential recovery actions. Staff said it has joined broader PFAS litigation efforts and is exploring state and federal grant opportunities to offset remediation costs but cautioned that quantifying liability and pursuing cost recovery will be complex.

Public health and technical limits: Delegates asked whether the injected carbon can be removed; Paquin said the PRB is created by injecting a carbon slurry that is not recoverable and that the approach is considered a medium‑term engineering control (current field data show efficacy over roughly a decade, though long‑term data are limited). Consultants and county staff said ongoing wellhead treatment at municipal systems will likely remain necessary as a polishing measure while downgradient concentrations decline.

Ending: County staff invited delegates to site visits and to a public update at the end of July; consultants expect to complete a Phase 2 comprehensive site assessment and ecological risk assessment by year‑end and to present updated monitoring results and modeling at future briefings.