Consultants say PFAS plumes near Yarmouth are complex; town pushes for more sampling and regulatory oversight

Consultants from Kleinfelder told the Yarmouth Select Board on April 15 that per‑ and polyfluoroalkyl substances (PFAS) detected in local soils, groundwater and some surface waters appear to come from multiple sources and that existing clean‑up and monitoring efforts may not fully define the extent of contamination.

The consultants said the data collected to date show several plumes — including contamination linked to a firefighting training academy and airport activities — but also additional unidentified plumes. They urged expanded sampling in Yarmouth surface waters and groundwater, continued participation in the regional stakeholder work group, and stronger engagement with the Massachusetts Department of Environmental Protection to require more complete delineation and public review.

Why it matters: PFAS are persistent chemicals associated with developmental, liver and immune effects in high‑exposure populations. Yarmouth officials and residents have raised concerns about PFAS in Mill Creek and other local waterbodies, shellfish, and impacts to conservation land. Consultants warned that the current regulatory focus on a small set of PFAS compounds may miss other related chemicals present in the environment.

Nate Stevens and Lisa Stone of Kleinfelder, the town’s hired consultants, described the technical challenges to the board. They said PFAS are a large family of chemicals (thousands of variants), commercial laboratory methods typically test tens of compounds, and Massachusetts currently regulates a small subset. That mismatch means investigators can detect many compounds for which there are no regulatory cleanup levels, complicating source identification and risk assessment.

Kleinfelder summarized prior investigations by state and academic groups and noted sites with identified releases: an airport and a separate firefighting training area. The consultants described several plumes mapped in regulatory filings and publicly available studies and said the airport’s three monitoring wells (the MAR wells) have been relied on to demonstrate capture of certain plumes — but the consultants questioned whether those wells fully contain contamination, citing detections of airport‑linked tracer compounds in surface water samples collected in Yarmouth.

Kleinfelder recommended a ‘‘weight of evidence’’ approach that compares full compound suites across samples rather than focusing on a single tracer; additional monitoring wells and groundwater sampling in Yarmouth; surface‑water resampling to reproduce results from prior studies (USGS, Harvard, SoleSource/HYannis Park group); and use of permeable reactive barriers or other containment where appropriate. They also noted a recent pilot of a permeable reactive barrier at the firefighting training site intended to limit offsite migration.

Board reaction and next steps: Select Board members said the town should press MassDEP for more aggressive sampling and public review. Member Mark Forrest asked Kleinfelder to prepare a written summary and recommendations; the consultants said they would submit a draft report to town staff the following week. Board members said they wanted the report in time to develop a formal request to MassDEP before the board’s May 6 meeting.

The consultants and the board discussed whether to sample shellfish and shellfish tissue; Kleinfelder said shellfish testing had been done elsewhere and PFAS has been detected in tissue, and said targeted tissue monitoring in areas such as Mill Creek or nearby shellfish beds is technically feasible and could be included if the town wants to document potential ecological or public‑health impacts.

Kleinfelder emphasized that the town is not a potentially responsible party and therefore cannot compel other parties’ cleanup decisions; rather, Yarmouth can request that MassDEP require more complete delineation and immediate response actions if regulators determine migration to surface water constitutes a substantial release.

The Select Board directed staff and Kleinfelder to refine recommendations and draft comments for distribution to MassDEP and the regional PFAS working group.

Kleinfelder speakers: Nathan Stevens, professional geologist; Lisa Stone, project manager.

Ending: The consultants said progress is being made through a regional stakeholder work group and recent additional monitoring, but stressed that more testing across compound suites and in Yarmouth surface waters and groundwater is needed to understand plume extent and potential ecological or human health exposures. The Select Board asked Kleinfelder for a written summary to support a formal request to MassDEP.