U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Wolff-Alport Chemical Company Radiological Site RV2

Site Contact:
Eric M. Daly
On-Scene Coordinator


Site Location:
1125-1139 Irving Avenue
Ridgewood, NY 11385

The Wolff-Alport Chemical Company (“Wolff-Alport”) operated at the property from the 1920s until 1954, importing monazite sand via rail and extracting rare earth metals from the material. Monazite sand contains approximately 6-8 percent or more of thorium and 0.1-0.3 percent of uranium. The acid treatment process used by Wolff-Alport converted the phosphate and metal component of the monazite to aqueous species, rendering the rare earth materials extractable while dissolving the thorium and uranium in an acid, such as sulfuric and nitric acid, generating waste process liquors and tailings. This process concentrated thorium-232 (Th-232) and uranium-238 (U-238), both of which are radioactive, in the process liquors.

During its operation, Wolff-Alport occupied three structures that currently comprise Lots 42 and 44, located at 1127 and 1129 Irving Avenue. Wolff-Alport’s operation included two-yard areas--one between the buildings on Lot 42 and the other on the eastern end of the property at the northern end of Moffat Street. These areas were reportedly used as staging areas for monazite sands or waste tailings containing Th-232 and U-238. The waste tailings were likely spread or buried on the property. Wolff-Alport likely disposed of the liquid process wastes into the sewer. According to the U.S. Department of Energy, the Atomic Energy Commission (“AEC”) ordered Wolff-Alport to halt sewer disposal of thorium waste in the fall of 1947. Thereafter, thorium was precipitated as thorium oxalate sludge and later sold to the AEC. The former operations caused surface and subsurface soil contamination to at least a depth of 20 feet, along with contamination underneath public sidewalks, city sewers, and nearby streets.

At the request of EPA, the Agency for Toxic Substances and Disease Registry (“ATSDR”) prepared a Health Consultation for the Site on February 29, 2012. The Health Consultation discusses the health issues associated with radiation exposures. ATSDR uses health-based comparison values to screen radiation levels and doses against health-based comparison values known as Minimal Risk Levels (“MRLs”). MRLs are an estimate of daily human exposure to a hazardous substance that is unlikely to have an appreciable risk of adverse cancer and non-cancer health effects over a specified route and duration of exposure. The ATSDR MRL for ionizing radiation, regardless of the source, is 100 millirems per year above ambient background levels.

ATSDR modeled radiologic doses at the Site based on certain assumptions to determine exposures. The ATSDR Health Consultation concluded that as a result of the radiological contamination at the Site, workers and pedestrians who frequently use sidewalks on Irving Avenue may have elevated risk of cancer from exposure to ionizing radiation and their exposures may exceed the ATSDR MRL. ATSDR also provided a number of recommendations to reduce radiation exposures.

On August 31, 2012, the New York State Department of Environmental Conservation and the New York State Department of Health requested in writing EPA assistance in reducing potential exposures posed by residual radioactive contamination at the site.

From August 2012 until August 2014, EPA Region 02 Removal Program conducted a removal assessment and action to address the radiological threats. Please see Wolff-Alport Chemical Company RV1 Website for details of the RV1 Removal Action.

On December 08, 2020, EPA assessed the sidewalk shielding at the Site. EPA discovered that due to the heavy traffic and continued business operations on the sidewalk shielding since 2013, the shielding has been compromised. EPA identified that the slip resistant top layer of the steel has been chipped away and is deteriorating in multiple areas. This compromised shielding poses an increased ionizing radiation exposure threat to the public and business occupants. There is a potential for ingestion of material beneath the sidewalk if the shielding deteriorates and exposes that material. The continued degradation of the shielding may also expose the Lead (Pb) middle layer of the shielding.