The Wolff-Alport Chemical Company site sits on about 0.75 acres in Ridgewood, Queens, New York. The company extracted rare earth metals there from the early 1920s until 1954 and disposed of thorium waste into sewers and possibly buried it on the property. EPA added the site to the National Priorities List (NPL) in May 2014 after radiological surveys found levels above typical background and identified potential health risks to on-site workers and frequent sidewalk pedestrians.
Eight contaminants of concern have been identified across the site. These include thorium-232, radium-226, benzo[a]pyrene, and polychlorinated biphenyls (PCBs). Contamination is present in soil, sludge, and downstream sewer lines. EPA has determined that human exposure is under control and that contaminated groundwater migration is stabilized, with no unacceptable discharge to surface water.
EPA took early protective steps between 2012 and 2014, including installing concrete, lead, and steel shielding in three buildings and over the Irving Avenue sidewalk, placing crushed rock over a former railroad spur, and installing radon mitigation in one building. A Record of Decision (ROD) issued in September 2017 called for permanent relocation of tenants, building demolition, soil and sewer sediment excavation, sewer cleaning, and off-site disposal of all contaminated materials. A 2024 Explanation of Significant Differences modified the remedy to add or adjust specific elements and introduce institutional controls, which are legal mechanisms that restrict land use to prevent exposure.
By early September 2023, all tenants had vacated following a federal court order. The demolition contractor secured and mobilized at the buildings in late September 2023. Active soil excavation began in late May 2025. New York City is responsible for designing and executing cleanup of contaminated sewers and soil beneath streets and sidewalks. Construction is not yet complete, and a five-year review is estimated for late 2028. The site has not yet been deleted from the NPL.
Community members can stay informed by signing up for EPA's mailing list. EPA held a community poster session on May 5, 2025 covering the site's history and cleanup progress, and fact sheets from that event are available in English and Spanish. Site records can be reviewed at the Washington Irving Library at 360 Irving Avenue in Brooklyn or at EPA's Superfund Records Center at 290 Broadway in New York. For questions, residents can contact the EPA staff assigned to the site.
