The 9.6-acre Middlesex Sampling Plant is located approximately 26 miles southwest of Newark, New Jersey.

From 1943 to 1967, the site was used to store high-grade uranium ore (known as pitchblende) from the Belgian Congo and, later, to process and ship uranium, thorium, and beryllium ores and store thorium residues. The facility was used as a U.S. Marine Corps reserve training center from 1967 to 1979, when DOE acquired the site. DOE cleaned up contaminated vicinity properties in the 1980s and stored excavated soil at the site. The U.S. Army Corps of Engineers completed site cleanup and disposed of 68,000 cubic yards of contaminated soil in 1998 and 1999.

DOE owns the Middlesex Sampling Plant property. When remediation is complete, DOE will consider selling or transferring the property for beneficial reuse.