Portsmouth receives update on Coakley Landfill Superfund work; $980,000 DES grant secured for PFAS pilot

Portsmouth planning and sustainability staff briefed the City Council on Aug. 3 about the status of cleanup work at the Coakley Landfill Superfund site, including recent findings of 1,4‑dioxane and PFAS and plans for a pilot removal project.

"This presentation is really a general overview of the Coakley Landfill Superfund project to update the council on the status and current activities of the site," Planning and Sustainability Director Peter Britz told the council. He described the site's operable-unit structure, the EPA and New Hampshire Department of Environmental Services oversight, and decades of monitoring and remedial work that followed federal litigation and consent decrees in the 1990s.

Britz said monitoring has expanded to include private water wells and additional sampling after the 2016 direction to test for new contaminants. "Since the completion of the landfill cap in 1998, the levels of contaminants of concern in groundwater have been significantly reduced," he said, but noted that testing in 2016 and later found 1,4‑dioxane and PFAS compounds in both Operable Unit 1 (the capped landfill) and Operable Unit 2 (the surrounding groundwater management zone).

The landfill group has since conducted a deep-bedrock study and additional investigations to better understand groundwater flow. As a result of a recent EPA risk assessment and subsequent order, the Cochlear/Coakley Landfill Group is moving forward with a non–time‑critical removal action and an engineering evaluation/cost analysis (EE/CA). Britz told the council the group successfully secured a grant from New Hampshire DES for $980,000 "to initiate and pay for the pilot treatment project to remove PFAS."

Councilors asked about measurement of influent and effluent for PFAS and 1,4‑dioxane; Britz confirmed monitoring will include influent and effluent testing as part of the pilot. He described likely intercept-and-treat approaches, drilling of new monitoring wells along expected flow paths, carbon filtration for pumped water and options for discharge or reinjection after treatment. Staff said bidding for a consultant and engineer to design the pilot is under way and that selection should be completed within months.

The council discussed public transparency and long-term protections for drinking water. Councilors and the mayor emphasized that the work is EPA‑led and noted previous actions to extend municipal water lines to reduce exposure risks. The Coakley Landfill Group — which includes Portsmouth and neighboring municipalities as potentially responsible parties — will continue to implement the remedy under EPA oversight.

Next steps: the EE/CA will be completed and a consultant selected to develop and oversee the pilot treatment project; staff said monitoring and reporting will continue and that property owners with impacted private wells have been provided filtration systems or public water where necessary.