Update: Upcoming Middlesex Sampling Plant Vicinity Property Investigations
The U.S. Army Corps of Engineers (USACE) New York District is conducting environmental investigations and survey activities related to the former Middlesex Sampling Plant (MSP) site located at 239 Mountain Avenue in the Borough of Middlesex, Middlesex County, New Jersey. The MSP was established in 1943 as part of the Manhattan Engineer District (MED) to sample, store, test, and transfer ores containing uranium, thorium, and beryllium. The ongoing site work is being performed under the Formerly Utilized Sites Remedial Action Program (FUSRAP), a program that is cleaning up sites with contamination resulting from the nation’s early atomic energy program.
project background
The 9.6-acre MSP is a legacy MED and U.S. Atomic Energy Commission facility that received uranium, thorium, and beryllium ores from the 1940s until 1967, when the facility was decontaminated to the standards in effect at the time. However, overlooked during decontamination were traces of radioactive materials that had been carried off-site over the years by wind or rain, or removed from the site for use as fill at nearby properties. Also, records later revealed that in 1948, some radioactively contaminated materials had been trucked from the plant to the Middlesex Municipal Landfill (MML), one-half mile away.
In the 1980s, the contaminated nearby properties (referred to as MSP Vicinity Properties) were cleaned up, and the excavated soil was stored on the MSP site in a specially constructed pile, known as the Vicinity Property Pile.
A Record of Decision (ROD) was signed in 2005 that specifies the criteria for the cleanup of contaminated soil related to the MSP. Cleanup of the MSP soils was completed in 2008. USACE conducted a review of the MSP Vicinity Properties previously identified by the U.S. Department of Energy to ensure they meet the criteria set in the ROD. In 2019, USACE added a new Vicinity Property to the MSP. The location of this VP suggested that a wider area around the MSP be further investigated. In 2021, USACE conducted an expanded aerial survey extending 12 square miles around the MSP Site.
current activities
The aerial survey results show that there is no immediate threat to people’s health or the environment. However, USACE will continue ground investigations this year on public and private properties. Work crews will conduct visual observations, perform surface scans, and collect soil samples. The additional data collected will help to confirm the aerial survey results. It is important to note that USACE investigating a property does NOT mean there is contamination. Similarly, elevated readings do not necessarily indicate contamination because there are many sources of naturally occurring radiologic activity in our environment that can cause elevated readings, such as granite stone and building materials like brick. Work conducted by USACE will help determine whether radiological levels on the properties investigated are consistent with naturally occurring radioactive material. As with the previous USACE work at this site, these investigations are being conducted in coordination with both the U.S. Environmental Protection Agency (EPA) and the New Jersey Department of Environmental Protection (NJDEP).
more information
Middlesex Sampling Plant Vicinity Property Investigation Fact Sheet
Middlesex Borough Evaluation Areas July 2025
Study Area Overview July 2025