The 6.4-acre W.R. Grace & Company, Inc./Wayne Interim Storage Site (WISS) is located in Wayne, New Jersey. In 1948, Rare Earths, Inc. began using the site to extract thorium and rare earth metals from monazite sand. After the Atomic Energy Act was passed in 1954, the Atomic Energy Commission (AEC) formally licensed the site to conduct these operations. The facility was acquired by Davison Chemical, a division of W.R. Grace & Company, Inc., in 1957 and continued to process monazite ore until 1971. The extraction process used at this facility involved cracking the monazite by heating it in sulfuric acid, followed by selectively precipitating the thorium and desired metals using ammonium hydroxide, sodium hydroxide, and hydrogen peroxide. This created wastes and residues such as ore tailings, sulfate precipitates, and yttrium sludges. A wastewater treatment plant operated on-site to treat liquid effluents. Once treated, the wastewater was discharged into Sheffield Brook, a tributary of the Pompton River in the larger Passaic River watershed. Wastewater treatment residues were disposed of in a sludge dump on-site.

Radioactive wastes were placed in piles around the facility prior to 1960. Between 1960 and 1971, wastes were disposed of in unlined pits. Applied Health Physics, Inc. decontaminated the buildings in 1974, and W.R. Grace demolished them and buried the debris shortly after. The waste disposal areas were covered with clean fill to reduce gamma radiation levels to below 0.2 millirad per hour (mrad/hr). The Nuclear Regulatory Commission (NRC) released the land for unrestricted use in 1975, under the condition that the deed would indicate the presence of radioactive material buried on-site.

Between 1980 and 1983, the New Jersey Department of Environmental Protection (NJDEP) found elevated radiation levels at the site and on properties west of the former facility, including an adjacent school bus maintenance yard, Sheffield Park, the banks of Sheffield Brook, and the Pompton Plains railroad spur. The primary radioactive contaminants were radium-226, thorium-232, uranium-238, and their daughter products. The chemical Contaminants of Concern (COCs) were antimony, arsenic, chromium, lead, mercury, molybdenum, and thallium.

The Environmental Protection Agency (EPA) added the site to the National Priorities List (NPL) of Superfund sites in 1984. The U.S. Department of Energy (DOE) managed the remediation from 1984 until 1997 under the Formerly Utilized Sites Remedial Action Program (FUSRAP), a program that cleaned up contamination from early AEC activities. Between 1984 and 1987, contaminated soils and debris from the adjacent properties were placed in an interim storage pile on the site until a disposal facility was located that was licensed or permitted to accept the radioactive wastes. The U.S. Army Corps of Engineers (USACE) took over the remedial activities in 1997. Approximately 135,000 cubic yards of contaminated material was removed, and the contaminated sites were cleaned to the “residential use” standard. After the remedial actions were completed, the site was removed from the NPL in 2012. Ownership of the site was transferred to Wayne Township and it has since been redeveloped into a park.