From the 1890s through 1941, the Welsbach Company and General Gas Mantle Company coated gas mantles with thorium to make them glow brightly. The leftover radioactive waste was spread as fill across nearly 1,000 residential, commercial, and recreational properties in Camden and Gloucester City, New Jersey. EPA added the site to the Superfund National Priorities List in 1996 after elevated gamma radiation was found throughout the area.
The main contaminants are radioactive materials including radium-226, radium-228, thorium-232, radon, and radon-222. The site also contains heavy metals such as arsenic, antimony, selenium, and thallium, along with polycyclic aromatic hydrocarbons and the polychlorinated biphenyl aroclor 1248. These contaminants were found in soil, debris, groundwater, and building structures. Radium-228 has also been detected in groundwater.
EPA has excavated and disposed of more than 400,000 tons of radiologically contaminated soil and waste since cleanup began in 2000. Completed work includes the Gloucester City Swim Club, a middle school, recreational properties along Johnson Boulevard, and 184 of the 211 identified contaminated properties. The Armstrong Building was fully decontaminated by 2016. A no-action decision was issued for wetlands and sediments. A groundwater cleanup plan issued in September 2021 calls for monitoring and institutional controls to address a radium plume at the former Welsbach facility. In January 2025, EPA issued an amendment to the original 1999 cleanup plan for soils, modifying the approach based on updated information about contamination volume, cleanup time, cost, and treatment area. The current status is "Current Human Exposure Not Controlled" because soil cleanup in residential neighborhoods is still ongoing. Groundwater migration is under control, and public supply wells in Gloucester City have not exceeded regulatory limits for radiological parameters.
The former Welsbach property now operates as the Gloucester Marine Terminal, an active Delaware River port. The Gloucester City Middle School opened there in 2017, and as of December 2024, 123 on-site businesses employed 1,603 people. Community members can contact EPA's Community Involvement Coordinator. The Remedial Project Managers also handle site questions and can be reached through EPA's New York office.
