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National Information |
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Superfund Program
Monticello Mill Tailings (DOE)
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Site Type: Final NPL City: Monticello County: San Juan Street Address: T33S - R23E Sec 36% T33S - R24E Sec 31 Zip Code: 84535 EPA ID#: UT3890090035 Site ID#: 0800867 Site Aliases: AEC Millsite Congressional District(s): 03 |
Site Status & Updates
Soil contamination has been removed from the former mill site and peripheral properties, except where supplemental standards have been applied. Restoration of the mill site was completed in 2001. The interim remedial action for surface and ground water has begun, and a final remedy is expected to be selected in 2004.
This site, except for the surface- and ground-water operable unit, was transferred to DOE's Long-Term Surveillance and Maintenance (LTSM) program in 2001. Under the LTSM program, the repository and properties granted supplemental standards will be monitored and maintained to make certain that the selected remedies remain protective. A CERCLA 5-year review will be conducted in 2002
The cleanup is being addressed through a Federal Facilities Agreement. The DOE is the lead federal agency. EPA placed the site on the National Priority List in 1989.
Soil contamination has been removed from the former mill site and peripheral properties, except where supplemental standards have been applied. Restoration of the mill site was completed in 2001. The interim remedial action for surface and ground water has begun, and a final remedy is expected to be selected in 2004.
This site, except for the surface- and ground-water operable unit, was transferred to DOE's Long-Term Surveillance and Maintenance (LTSM) program in 2001. Under the LTSM program, the repository and properties granted supplemental standards will be monitored and maintained to make certain that the selected remedies remain protective. A CERCLA 5-year review will be conducted in 2002.
Site Description
The Monticello Mill Tailings site, a former U.S. Department of Energy (DOE) processing facility, lies in the Montezuma Creek Valley, east of the Abajo Mountains in southeastern Utah. The former mill site, on 78 acres of land, is bordered by the City of Monticello.
The mill was constructed by the Vanadium Corporation of America in 1942. In 1944 the mill began production of a uranium/vanadium sludge for the Manhattan Engineering District. In 1948, the US federal government bought the site. Mill operations stopped and tailings were stabilized in1960. In1964, the mill was dismantled.
Site Risk
The ground water and surface water are contaminated with uranium, as well as its radioactive decay products, thorium 230, radium 226, radon 222 and heavy metals from tailings deposited on the site, including arsenic, selenium, vanadium, molybdenum, manganese, etc. Exposure to uranium through contact with ground water may be a potential threat to the health of individuals in the vicinity.
The City of Monticello has its own water system, supplied by water from springs located on the flanks of the Abajo Mountains. The domestic water source for those people living outside the city limits is ground water drawn from wells completed in the Burro Canyon Formation. There is no known contamination of the domestic water supplies attributable to contamination from the site.
| Media Affected | Contaminants | Source of Contamination |
| Soils, surface water, ground water, sediment, sediment, solid waste | Uranium, thorium 230, radium 226, radon 222 and heavy mteals including arsenic, selenium, vanadium, molybdenum, manganese | Uranium milling operations |
Cleanup Progress
Former Mill Site and Tailings Piles:
Construction of the repository was initiated in 1995, and the excavation, transportation and placement of contaminated material began in 1997. An evapo-transpiration cover was recently constructed on the repository and is currently being revegetated. Reclamation of the former mill site is expected to be completed in 2001.
DOE completed the transfer of 383 acres of land to the City of Monticello in 2000. DOE has also entered into a Cooperative Agreement with the City of Monticello, as the city will be responsible for final restoration of the mill site. Restoration of one mile of Montezuma Creek and five acres of wetland was completed in September 2001. About 150 acres, including the former mill site, were reseeded.
Peripheral Properties:
Thirty-four peripheral properties with contamination have been identified. Contractors excavated contaminated materials, moved them to the repository, and revegetated disturbed areas. In 2002, DOE is proposing a partial deletion which will include 23 of the peripheral properties.
Surface Water and Ground Water:
In 1998, the DOE completed an investigation of surface water and ground water and the impact to human health and the environment from contaminated soils and sediments that have been transported downstream by Montezuma Creek. An interim remedial action Record of Decision was signed in September 1998. The interim remedial action includes:
- Institutional controls to restrict the use of contaminated ground water;
- Treatment of contaminated surface and ground water during source removal;
- Monitoring of the contaminated ground-water system; and
- Construction of a permeable reactive-treatment wall for ground water at the mill-site boundary.
A removal action of hot-spot contamination in the Montezuma Creek flood plain has been completed downstream from the mill site. Supplemental standards are in place, and the Utah state engineer has placed a restriction on the construction of any groundwater wells within the contaminated plume. In 1999, a PeRT wall (permeable reactive treatment wall) was complete down-gradient of the mill site. This is a full-scale treatability study to determine the effectiveness of the reactive barrier to remove contaminants from the ground water.
Site Documents
Note: the following documents are Adobe PDF files
About PDF files
Five-Year Review - June 2007 (PDF, 61pp, 1.1 MB)
Five-Year Review Update -June 2008 (PDF , 3 pp, 32KB)
Contacts
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EPA Paul S. Mushovic Ted Linnert |
Utah David Bird, Project Manager Dave Allison |
| Department of Energy
Raymond Plieness Monticello City Office |
View Documents at: U.S. EPA Superfund Records Center |
