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Two scrapers work together to excavate Mancos Shale at the Crescent Junction site to create the second portion of a disposal cell for uranium mill tailings
One of two gantry cranes that load and unload tailings containers from the railcars is pictured on the hillside rail bench west of Moab
Uranium Reduction Company constructed the Moab mill in 1956 and operated it until 1962 when the assets were sold to Atlas Minerals Corporation (Atlas). Uranium concentrate (called yellowcake), the milling product, was sold to the U.S. Atomic Energy Commission through December 1970 for use in national defense programs. After 1970, production was primarily for commercial sales to nuclear power plants.
During its years of operation, the mill processed an average of about 1,400 tons of ore a day. The milling operations created process-related wastes and tailings, a radioactive sand-like material. The tailings were pumped to an unlined impoundment in the western portion of the property that accumulated over time, forming a pile more than 80 feet thick. The tailings, particularly in the center of the pile, have a high water content. Excess water in the pile drains into underlying soils, contaminating the ground water.
Atlas operated the site until 1984 under a license and regulatory authority provided by the U.S. Nuclear Regulatory Commission (NRC). When the processing operations ceased, an estimated 16 million tons (12 million cubic yards) of mill tailings and tailings-contaminated soil was present in the pile. The tailings have an average radioactivity of 665 picocuries per gram of radium-226. Atlas placed an interim cover over the tailings pile as part of decommissioning activities conducted between 1988 and 1995.
Atlas proposed to stabilize the tailings pile at Moab by permanently capping it in place; however, Atlas declared bankruptcy in 1998 and, in doing so, relinquished its license. Because NRC could not legally possess a site it regulated, NRC appointed PricewaterhouseCoopers as the trustee of the Moab Mill Reclamation Trust and licensee for the site. The trustee initiated site reclamation, conducted ground water studies, and performed site maintenance activities.
The Moab site is located about 3 miles northwest of the city of Moab in Grand County, Utah. The former millsite encompasses approximately 435 acres, of which about 130 acres is covered by the mill tailings pile. Through donation in 2011 of the adjacent private property to the south, the DOE property now consists of almost 500 acres. Other federally owned land now borders the site on the south. Sandstone cliffs border the site on the north and southwest. The Colorado River forms the southeastern boundary. U.S. Highway 191 parallels the northern site boundary, and State Route 279 crosses the western portion of the site. Figure 2 shows some of the site features.
The scope of the Moab UMTRA Project is to relocate mill tailings and other contaminated materials from a former uranium-ore processing facility (millsite) and from off-site properties known as vicinity properties in Moab, Utah, to an engineered disposal cell constructed near Crescent Junction, Utah. The scope also includes active remediation of ground water at the millsite (Moab site). Figure 1 shows the general location of the project sites.
NATIONAL ENVIRONMENTAL POLICY ACT IMPLEMENTATION
DOE developed an Environmental Impact Statement (EIS) to fulfill the National Environmental Policy Act requirement of considering the full range of reasonable alternatives and associated environmental effects of significant federal actions. In July 2005, DOE published the final EIS that presented the preferred alternatives of off-site disposal of the tailings pile and other contaminated materials at the Crescent Junction site using predominantly rail transportation, and active ground water remediation at the Moab site. In September 2005, DOE issued the Record of Decision, which detailed the selection of the preferred alternatives and the basis for that decision. DOE amended the Record of Decision in February 2008 to allow for more truck transport.
GROUND WATER INTERIM ACTION
DOE utilized previous investigations along with additional soil and ground water sampling to assess the extent of contamination at the Moab site. Elevated concentrations of ammonia can affect young-ofyear endangered fish species in backwater channels adjacent to the Colorado River bank. In 2003, DOE began implementation of an interim action system that currently includes 8 extraction and more than 30 freshwater injection wells. The system is designed to protect surface water quality and to recover ammonia, uranium, and other contaminants prior to discharge to the Colorado River.
TAILING REMOVAL AND TRANSPORTATION
In 2008 and 2009, DOE performed extensive infrastructure construction at the Moab and Crescent Junction sites in preparation for moving the mill tailings. In April 2009, DOE began relocating the tailings to the disposal cell. Tailings are excavated and conditioned in drying beds on top of the pile to reach the optimal moisture content for disposal. The tailings are then placed in steel containers with locking lids for transport to Crescent Junction. Gantry cranes are used to transfer containers to and from the train at Moab.
With additional funding received through the American Recovery and Reinvestment Act of 2009, DOE increased the amount of tailings transported for disposal each week between June 2009 and July 2011. The Recovery Act funding has been expended, and the project is currently shipping one train a day, 4 days a week, carrying up to 136 containers for a total of about 4,850 tons per trainload. In February 2012, 5 million tons of tailings, about 31 percent of the total tons. The project is currently estimated to be completed in 2025.
CRESCENT JUNCTION DISPOSAL SITE INFORMATION
The Crescent Junction site is located northeast of the eastern junction of Interstate Highway 70 and U.S. Highway 191, approximately 30 miles north of the Moab site. This location was selected primarily because of its ideal geological setting. Through a series of temporary withdrawals of public domain land and a permanent land transfer by the Department of the Interior, DOE currently owns 500 acres of land and has another 936 acres in a 20-year withdrawal for the disposal cell and surrounding buffer area, the support area, and access road. The permanent transfer area will be fenced when the cell is completed.
At the Crescent Junction site, the containers carrying tailings are unloaded from the train onto trucks that take them to the disposal cell dumping area. The tailings are dumped through end gates in the containers and placed in the cell in 1-foot lifts to meet compaction specifications. The empty containers are reloaded onto railcars and returned to the Moab site.
The cell is rectangular and is aligned in a west-to-east direction. The completed cell will be about 5,200 feet long by 2,400 feet wide and is being constructed in phases. The cell is excavated about 25 feet below the existing grade and the estimated aboveground height of the compacted materials is 25 feet. The top of the contaminated materials is being capped with a 10-foot thick, multi-layered cover composed of native soils and rock.