In the United States, uranium ores were processed at several facilities at different times during 1940s
to produce concentrate for Government requirements during World War II and afterward from 1947
through 1970 under the U.S. Atomic Energy Commission's uranium procurement program. Prior to
1940, uranium-bearing ores were processed and tailings residues produced at several of these sites
to recover radium, uranium, and later vanadium in response to the then-current industrial
requirements.
The uranium content of domestic sandstone ores typically treated from 1940-1970 was on the order
of 0.05 to 0.25 percent by weight, or 1 to 5 pounds U3O8 per ton of ore treated. Each of the uranium
mills utilized a somewhat different chemical-process technology to treat the raw ore and produce an
intermediate, semi-refined product commonly called "yellow cake." The treatment of low-grade, raw
ore at other sites involved uranium upgraders, concentrators, heap-leach piles, and lignite burners
to remove the undesirable ore constituents and concentrate the uranium values, along with desired
co metals in some cases, into a product that could be economically shipped to a mill for final
processing. The mill tailings from these milling and processing operations typically consisted of a slurry
containing the ground-up, sand- and clay-size, waste-rock particles, most of uranium-daughter
radionuclides, and hazardous chemical residues. After final recovery of uranium from the ore, the tailings material typically contains about 85 per cent of the natural radioactivity originally
present in the raw ore.
The hazardous chemicals and radionuclides contained in uranium tailings, if not properly stored, can
negatively affect the natural environment, including the air, soil, and groundwater. In the United
States beginning in the late 1960s and early 1970s, a appreciation was developed for the potential
health hazards and the severity of environmental disturbances that had accumulated over the long
history of domestic uranium ore mining and processing. These problems were primarily the results
of ineffective regulatory oversight in governing mine discharges, hazardous waste disposal, and
unreclaimed mining sites. This led to the passage, of several U.S. Federal and State laws designed
to protect air, water, and land resources.
In 1966, a study found that uranium mill tailings material that had been used in the construction of
homes, schools, and other buildings in and around Grand Junction, Colorado, constituted a health
hazard. The tailings had been removed from the uranium mill site located in Grand Junction. The
direct gamma radiation and radon gas and its decay products from the tailings were the principal
concern. The State of Colorado adopted regulations for stabilization and control of uranium mill
tailings by the mill owners. While some success in stabilizing tailings and controlling erosion of the
piles was achieved by this effort, the need for long-term solution for handling and disposal of the
uranium mill tailings remained.
In 1971, the Subcommittee on Raw Materials of the Joint Committee on Atomic Energy heard
testimony on the dangers and inherent public health threat from the use of uranium mill tailings
materials for construction at civilian sites, which later became known as vicinity properties. As a
result of these hearings, in 1972 Congress passed Public Law 92-314 (later amended by P.L. 95-238)
to provide authority and funding for a Federal-State cooperative program with the State of Colorado
to undertake remediation of structures in the Grand Junction area where mill tailings were used for
construction. The Government paid 75 per cent of the cost and the State paid the remainder.(1) This
law did not include funding to perform remedial action on the existing inactive Grand Junction mill
tailings site or other similar sites.
In 1973, a bill was introduced in the Senate (S. 2566) to authorize the U.S. Atomic Energy
Commission to enter a cooperative agreement with the State of Utah to conduct remedial action to
limit public exposure to radiation in the vicinity of the inactive uranium mill tailings site at Salt Lake
City, Utah. A similar bill was introduced in the House (H.R. 11378). The Subcommittee on Raw
Materials, Joint Committee on Atomic Energy, held hearings on the bills in March 1974.
Representatives from the AEC and the Environmental Protection Agency (EPA) presented testimony
that similar problems existed at other inactive uranium mill sites and that further study was
warranted. The AEC proposed a comprehensive program to assess the conditions at all inactive
uranium mill sites. The Committee agreed to this proposal and called for a two-phase study of the
inactive mill tailings at 22 sites with support from the EPA and the affected States. Phase I was
initiated cooperatively by the AEC and EPA in May 1974 and included an assessment of the physical
conditions at inactive uranium mill sites in eight western states. Phase II, which utilized the findings
from Phase I, consisted of an engineering assessment of the sites and the identification, evaluation,
and estimation of costs for remedial actions at each site.
In 1977, the detailed engineering assessments of inactive mill tailings sites were completed. As an
outcome to this work, the DOE submitted proposed legislation to Congress in April 1978. Hearings
began in June 1978 on the proposal and on related bills submitted by the Senate and House of
Representatives. In November, the Uranium Mill Tailings Radiation Control Act of 1978
(UMTRCA, P.L. 95 604) was passed. It authorized the DOE to enter into cooperative agreements
with the States and Indian tribes as well as persons who were owners or controllers of specific
inactive mill tailings sites in order to establish site assessment and remedial action programs. The
Federal Government would pay 90 percent of the remediation cost for designated sites in affected
States and it would pay all such costs for mill tailings sites on Indian lands.
DOE established the Uranium Mill Tailings Remedial Action Project (UMTRA) in 1979 to clean
up the congressionally designated Title I mill tailings sites. A seven-year completion deadline was
set for completion of the work. The UMTRA Amendments Act of 1988 extended the cleanup
authority to September 1994.
Under UMTRCA, three Federal agencies, EPA, DOE, and the U.S. Nuclear Regulatory Commission
(NRC), were assigned specific responsibilities. The EPA was directed to establish standards for
cleanup and disposal of contaminated material from both inactive and active uranium processing
sites. After taking into account the economic cost of implementing new standards and considering
public health, safety, and the environment, the EPA formulated standards to limit the release of
radon gas into the environment and require that any disposal methods be designed to control
radiological hazards for up to 1,000 years, to the extent achievable, and in any case for at least 200
years.
The UMTRCA legislation authorized the Secretary of Energy to designate any other sites that met
criteria written into the Act, and two such sites were later designated. Title I of the act covers sites
that were already inactive at the time the legislation was enacted.(2) Under the act, the DOE was
required to cleanup all Title I sites(3) to EPA's standards: this involved 24 sites and the associated
vicinity properties contaminated by the spread of hazardous radioactive materials by wind, water,
and human intervention.(4) In some cases, where tailings piles were exposed to weather, the local
groundwater became contaminated due to the effects of rain and snowmelt.
NRC, working with EPA, was required to establish regulations governing the control and cleanup
of the mill tailings and land at Title II sites. These sites are licensed by NRC or by the Agreement
State in which they are located. The NRC's regulations conform with and implement and enforce
EPA's general standards. Under UMTRCA, the Federal Government becomes the long-term
custodian for all sites cleaned up under Title I. The DOE will ultimately be responsible for costs of
long-term surveillance and maintenance of the Title I low level radioactive waste disposal sites. At
year-end 2000, DOE, under the Long-Term Surveillance and Monitoring Program (LTSM), had
custody and was responsible for the surveillance, monitoring, and maintenance of 27 low-level
radioactive waste disposal sites. By 2006, more than 60 such sites from various reclamation
programs are projected to be included in the DOE's LTSM program.(5)