wolff-alport chemical company

1125-1139 Irving Avenue

The Wolff-Alport Chemical Company (WACC) site is located on Irving Avenue and Cooper Avenue in Ridgewood, Queens County, New York, at the county border with Brooklyn. The site area includes a delicatessen/grocery, office space, residential apartments, auto and tire shops, two warehouses and a former rail spur which is now used for storage of large, steel crane equipment. WACC operated at the property from 1920 until 1954, extracting rare earth metals from monazite sands. Monazite contains approximately 6% to 8% thorium. Until 1947, WACC disposed of thorium waste in the sewer system (process liquors) and on the property (waste tailings). The Atomic Energy Commission (AEC) ordered WACC to halt sewer disposal of thorium waste in the fall of 1947. Thereafter, thorium was precipitated as thorium oxalate sludge and sold to the AEC. During its years of operation, WACC occupied three structures and two yards on Irving Avenue. The former yard areas, now occupied primarily by structures, were used as staging areas for monazite sands or waste tailings. WACC did not operate out of 1125 Irving Avenue or 1514 Cooper Avenue, but those properties are affected by site-attributable contamination. The property is contaminated with radioactive thorium-232 at concentrations up to 1,133 picocuries per gram (pCi/g), compared to background levels of 0.5-1.0 pCi/g. The radioactive decay of thorium-232, which has a half-life of 14 billion years, is a lengthy and complex process involving many radioactive decay products. One of the key components of the thorium-232 decay series is radon-220 (i.e., thoron), a radioactive gas that emanates from surfaces where thorium-232 is present. Thoron has been found at elevated levels in the deli basement, in air above the source material and outside the source boundary. The contaminated source area extends throughout the property and to some street and sidewalk areas. Thorium-232 concentrations at the site exceed the soil ingestion cancer risk level of 3.4 pCi/g, potentially affecting on-site and nearby workers, residents and students. Thoron poses a hazard from its radioactive decay products, which remain suspended in air where they can be inhaled and deposited in the lungs. There are more than 6,800 residents, students and workers within ΒΌ mile of the site and more than 1.8 million residents within 4 miles. There are several public schools and daycare facilities within 1 mile, the nearest of which is an elementary school 900 feet to the southwest. Residual contamination still exists in downstream sewer lines, which discharge to Newtown Creek during heavy rainstorms.

Hazardous Ranking Score

50 / 100

A score of 28.5 or higher qualifies a site for the Superfund National Priority List.

Regional Contact

Region 2
Phone: (877) 251-4575

Contact Region



Site Inspection
Preliminary Assessment
Final Listing On NPL

Contaminants & Health Effects

      Endocrine Disrupter
      Reproductive Toxin
      Persistent, bioaccumulative and toxic


        African American
        American Indian and Alaska Native
        Native Hawaiian


        People living
        within a mile radius


        Average Income


        Occupied homes

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