Woburn reports slight PFAS exceedance for Q4; treatment plant design, funding and bidding move forward

WOBURN — City officials told the Woburn City Council on Feb. 6 that fourth-quarter PFAS sampling averaged 21 parts per trillion (ppt), just above the Massachusetts Department of Environmental Protection’s regulatory quarterly standard of 20 ppt, and that the city will mail a public notification to all postal patrons.

Mayor Michael Concannon introduced the presentation and said the city would share the results by mail and on the city website. Carol Riegel of CDM Smith, the consultant leading the technical update, described the city’s monitoring approach — monthly sampling aggregated to a quarterly compliance metric — and said January results were 13.5 ppt.

Riegel said the difference between state and federal approaches complicates direct comparisons: MassDEP measures the sum of six PFAS compounds with a 20 ppt threshold, while the U.S. Environmental Protection Agency’s (EPA) proposed rule would set a 4 ppt limit for PFOA and PFOS and use a unitless hazard-index approach for additional compounds. She said Horn Pond’s long-term averages for the two compounds EPA is targeting (PFOA and PFOS) are roughly 7–8 ppt and that, under the EPA proposal, treatment will be required to meet those limits.

On project timing and funding, Riegel told the council that final design was submitted to MassDEP in September and that technical responses were submitted in January. The project is on the state priority list, loan paperwork is flowing to the city, and Riegel said the project cost is “over $10,000,000.” Contractor prequalification is complete; the city plans to advertise bids at the end of February, with bidding through May. The construction contract must be awarded by June 30 under the funding timeline, Riegel said, and construction would proceed after the notice to proceed with completion and start-up anticipated in early 2026.

Councilors asked whether heavy rainfall correlates to higher PFAS levels. Riegel said some earlier patterns suggested links to precipitation but that recent years have not shown a consistent correlation; measured values have varied in a narrow band (Riegel noted a low–high range in the teens to low-20s ppt). She emphasized that the planned treatment system at Horn Pond would be capable of meeting the EPA-proposed limits for PFOA and PFOS.

The council placed the mayor’s communication on file after the presentation.