Ambrosia Lake (Umtra Site)

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NEW MEXICO UMTRA SITES

The Ambrosia Lake and Shiprock former processing sites are two of 24 uranium mill processing sites designated by the Uranium Mill Tailings Radiation Control Act for remediation by the Department of Energy. During the 1960s, private firms processed most of the uranium ore mined in the United States for the Atomic Energy Commission, a predecessor of the Department of Energy. Congress passed the Act in 1978 in response to public concern regarding potential health hazards from long-term exposure to uranium mill tailings. It authorized the Department of Energy to stabilize, dispose of, and control uranium mill tailings and other contaminated material at 24 uranium mill processing sites and vicinity properties. For a general discussion of the UMTRA Program, see the overview presented in the New Mexico section of this report.

The cost estimate model used for this report provides costs for each of the UMTRA sites. All costs for waste management activities, program management, and relevant landlord activities attributable to the Department are provided for within the scope of environmental management. There are no Uranium Mill Tailings Radiation Control Act sites with either current or planned nuclear material and facility stabilization activity needs. Funding for all sites is 100 percent nondefense.

Pursuant to the Uranium Mill Tailings Radiation Control Act, the Department of Energy entered into a Cooperative Agreement in 1985 with the State of New Mexico. The agreement outlines the roles and responsibilities of each party. The agreement also delineates the cost sharing arrangement which states that the Department of Energy is responsible for 100 percent of the assessment costs and 90 percent of the remediation costs, and the state is responsible for the remaining 10 percent of the remediation costs. The Nuclear Regulatory Commission concurred on the original agreement and is required to concur on all major modifications thereafter.

AMBROSIA LAKE (UMTRA SITE)

The former Ambrosia Lake mill and tailings site is located in McKinley County in northwest New Mexico approximately 40 kilometers (25 miles) north of Grants and 137 kilometers (85 miles) northwest of Albuquerque. The tailings covered approximately 42 hectares (105 acres). Wind and water erosion spread some of the tailings across a 231-hectare (570-acre) area.

FACILITY MISSION

The mission of the Ambrosia Lake mill site was to provide uranium for the United States Government. The sources of contamination were the residual tailings and discharged process water remaining after the uranium was extracted during the milling process. Phillips Petroleum Company originally operated the mill, which was built in 1957. United Nuclear Corporation purchased and operated the mill for a brief period in 1963. United Nuclear Corporation shut down milling operations in 1963 but retained ownership of the site. In the late 1970s and early 1980s, United Nuclear Corporation operated an ion exchange system, extracting uranium from mine water. Homestake Mining purchased United Nuclear Corporation's interest in 1981. The State of New Mexico currently owns the site.

The Environmental Management program is responsible for cleaning up surface- and ground-water contamination at the UMTRA sites. The Uranium Mill Tailings Radiation Control Act designated the residual radioactive material found at this site for cleanup and stabilization. The Act directed the Environmental Protection Agency to promulgate standards (Code of Federal Regulations Title 40, Part 192) and the Department of Energy to perform the cleanup. It also assigned the Nuclear Regulatory Commission to oversee and certify the cleanup and license the completed disposal cell.

FUTURE USE

The State of New Mexico currently owns the former processing site. When the Nuclear Regulatory Commission certifies that remedial action is complete, the State will transfer the deed for this site to the Federal Government under the custody of the Department of Energy. Access to the facility will remain restricted, and it will be monitored and maintained in accordance with the Nuclear Regulatory Commission approved-Long-Term Surveillance Plan.

ENVIRONMENTAL RESTORATION

Surface remedial action has been completed, and the source of contamination has been stabilized. However, residual milling-related contaminated ground water remains.

Surface Project

Remedial action was completed at the Ambrosia Lake former processing site in July 1995. The remedial action involved consolidating approximately 4.6 million cubic meters (6 million cubic yards) of residual radioactive material onsite in a 36-hectare (88-acre) disposal cell and remediating the five vicinity properties. This report assumes that the Nuclear Regulatory Commission will certify the remedial action in June 1996 and licence the disposal cell in June 1997. Administration of the site will transfer to the Grand Junction Projects Office Long-Term Surveillance and Maintenance program in September 1997.

Major Surface Project Activity Milestones

TASK	COMPLETION DATE Fiscal Year
Nuclear Regulatory Commission Issues General License	1997
Transfer to Grand Junction Projects Office Long-Term Surveillance and Maintenance Program	1997

The Ambrosia Lake Remedial Action Plan outlines the contaminant distribution and the required remedial action. The Remedial Action Plan, which requires Nuclear Regulatory Commission concurrence, was published in January 1992. Remedial action at the site was performed in two phases. Phase I began in late 1986 and included construction of decontamination facilities, asbestos removal, demolition of the mill building, and other site preparation activities. Phase II remedial action began in September 1992 and involved excavating and consolidating residual radioactive material, including the existing tailings, and stabilizing these materials at the present tailings location.

The UMTRA Surface Project will conduct surveillance and maintenance of the disposal cell after completion of remedial action and prior to its transfer to the Grand Junction Projects Office's Long-Term Surveillance and Maintenance program in FY 1997.

Ground-Water Compliance Project

The Department is developing a Programmatic Environmental Impact Statement pertaining to all 24 UMTRA sites. For a discussion of the Programmatic Environmental Impact Statement see the UMTRA program narrative in the New Mexico section of the report. After completion of the Programmatic Environmental Impact Statement, site-specific National Environmental Policy Act documentation will be developed to propose an appropriate ground-water compliance strategy and reasonable alternatives for the Ambrosia Lake site.

The cost estimates for this report assume that a compliance strategy requiring no further action will be selected. For all types of ground-water compliance strategies, once the Nuclear Regulatory Commission determines a site to be in compliance with Subpart B of the Environmental Protection Agency Standards and it is certified, no additional long-term surveillance or monitoring will be conducted.

The volume of contaminated ground water has not been assessed because the aquifer has been designated a limited use (class III) aquifer. Leach processing activities and the tailings left on the site were the sources of the contaminants. The uppermost aquifer at the site was created by past milling activities. The contaminants of potential concern are radium-226, selenium and natural uranium. The volume of contaminated ground water should diminish with time. Ground-water underflow and recharge in the area is minimal.

To define the extent of ground-water contamination, the Department of Energy collected water samples from 1980 through 1995. Results from the 1994 sampling event show that concentrations of molybdenum, nitrate, selenium, and uranium exceeded the Environmental Protection Agency maximum concentration limits for ground water in the alluvium and weathered Mancos Shale. Ground water in lower aquifers does not appear to have been contaminated by seepage from the contaminated ground-water units beneath the Ambrosia Lake site.

All water contained in the alluvium and weathered Mancos Shale at the site was initially derived from mining-related activities; therefore, no background water existed to be sampled. There are no potential receptors in the vicinity of the site because ground water in the uppermost water-bearing zone is not used for domestic or agricultural purposes. Based on existing data collection activities, it appears that the residual milling ground-water contamination has not spread offsite.

Direct Program Management/Support

Program management supports management efforts for the National Environmental Policy Act process, site characterization and licensing, public information/participation, applicable state and federal regulator costs, quality assurance audits, program and management support for the technical assistance contractor, special studies, document control, technical assistance contractor site and technical management, cost and schedule controls, planning and preparation of the federal budget, and the Environmental Management Progress Tracking System.

FUNDING ESTIMATE

The following table presents estimated funding information for the Ambrosia Lake site.