Portsmouth Naval Shipyard sits on Seavey Island in the Piscataqua River in Kittery, Maine. The Navy has built and repaired submarines there since 1917. Shipbuilding operations, landfill use, battery storage, and spills left contamination across seven distinct areas. The site was added to the federal Superfund National Priorities List (NPL) on May 31, 1994, and was removed from that list on February 16, 2024, after all cleanup goals were met.
Contaminants found at the site include polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), lead, benzene, arsenic, cadmium, copper, mercury, thallium, and other metals. These contaminants appeared in soil, groundwater, and offshore sediments. Chlorinated dioxins and furans were also found in soil at one location, and several PAH compounds were detected in offshore sediments.
Cleanup actions across all seven areas included excavating contaminated soils, placing engineered soil covers over remaining contamination, dredging offshore sediments, and disposing of materials off-site. Investigations between 2019 and 2021 also found per- and polyfluoroalkyl substances (PFAS) in groundwater above EPA screening levels in four of five areas tested. EPA determined that industrial workers are not at risk from PFAS exposure during normal shipyard operations. To protect people if the facility is ever converted to residential use, EPA expanded land use control (LUC) boundaries to cover the four affected areas in an October 2022 decision. Land use controls across the site restrict residential reuse and require proper handling of excavated soil during any future construction work. Remedial construction was completed between 2012 and 2019, and EPA issued a Final Closeout Report in July 2023.
Human exposure to contamination is under control, and contaminated groundwater is stabilized with no unacceptable discharge to surface water. The site achieved sitewide ready-for-anticipated-reuse status on June 26, 2023. EPA will continue operation, maintenance, and monitoring, along with five-year reviews. The most recent five-year review was completed on April 26, 2022, and the next is estimated for 2027.
Community members can review site documents at the Rice Public Library in Kittery, Maine, the Portsmouth Public Library in Portsmouth, New Hampshire, or the EPA Region 1 Records and Information Center in Boston, Massachusetts. For questions, community members can contact the EPA's Community Involvement Coordinator or Remedial Project Manager.
