Monticello is a small town located in the southeastern corner of Utah in San Juan County. Vanadium Corporation of America constructed the original Monticello mill in 1941 with Federal Government funding to provide vanadium during World War II. Operation of the mill at Monticello from 1942 until the early 1960s generated approximately 2.5 million cubic yards of low-level radioactive waste from processing uranium and vanadium ores. Contaminated materials from mill processing activities were distributed by wind and water and limited amounts were used for construction, resulting in contamination of 424 vicinity properties.

The Monticello Vicinity Properties Site was placed on the National Priorities List in 1986 as the Monticello Radioactive Contaminated Properties. The Monticello Mill Tailings Site was added in 1989. DOE entered into an agreement with the U.S. Environmental Protection Agency (EPA) and the State of Utah to clean up the tailings and tailings contaminated material under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA).

The Monticello Vicinity Properties Site was deleted from the National Priorities List on February 28, 2000, following verification of the remediation. Contaminated materials from the vicinity properties, peripheral properties, and the former millsite were deposited in a disposal cell south of the former millsite. Disposal cell cover materials were emplaced in 1999, and the cover was seeded in 2000.

Because of the complexity of the Monticello Mill Tailings Site, DOE divided the work into three manageable components called “operable units.” EPA, the State of Utah, and DOE agreed in March 2000 that deletion of the Monticello Mill Tailings Site would be accomplished with partial deletions. The first area to be deleted was designated as Operable Unit II Non-Surface and Ground-Water Impacted Peripheral Properties. These 22 properties were deleted from the National Priorities List in October 2003.

On June 28, 2000, the City of Monticello signed a quitclaim deed from the National Park Service that completed the transfer of 383 acres of government-owned land, including the former Monticello millsite, from DOE to the city. The city performed restoration work on the millsite as payment in lieu of construction under a DOE City of Monticello Cooperative Agreement.

The Record of Decision for Operable Unit III, contaminated surface and ground water of the Monticello Mill Tailings Site, is anticipated to be finalized by June 2004. The Record of Decision will specify monitored natural attenuation with institutional controls as the selected cleanup strategy for the contaminated surface and ground water.