ABANDONED URANIUM MINES ON THE NAVAJO NATION

Description and History

The Navajo Nation is situated on a geologic formation rich in radioactive ores including uranium. Beginning in the 1940’s, widespread mining and milling of uranium ore for national defense and energy purposes on the Navajo Nation led to a legacy of abandoned uranium mines (AUMs). Some Navajo residents may have elevated health risks due to the dispersion of radiation and heavy metal contamination in soil and water.

The Navajo Nation brought these concerns to national attention at a Congressional hearing involving EPA, DOE and BIA on November 4, 1993. During this hearing, EPA personnel provided testimony about its federal authority under Superfund Law and offered to assist the Navajo Nation. EPA initiated a study in 1994 aimed at assessing human exposure to radiation and heavy metals from every known abandoned uranium mine (AUM) on the Navajo Nation. EPA has provided this assistance through the Superfund Program. Response actions have been taken utilizing Superfund’s Emergency Response authorities and while remedial action, listing sites on the National Priorities List (NPL) is a possibility, but not likely.

In August 2007, EPA completed a large study identifying 520 AUMs. In October 2007, EPA testified at a House Oversight and Government Reform Committee hearing followed by a meeting with select committee members to identify and respond to current issues raised by the Navajo Nation. EPA and several other Federal agencies are currently developing Five Year Action Plans to address AUMs and related issues.

In June 2008, the U.S. Environmental Protection Agency, in partnership with the Department of Energy, the Bureau of Indian Affairs, the Indian Health Service and the Nuclear Regulatory Commission,finalized a five-year plan for cleaning up the legacy of abandoned uranium mining on the Navajo Nation. A copy of this plan can be found by accessing the link below under Site Documents and Reports or by clicking HERE. A web-feature was also created to highlight this accomplishment and that can be accessed by clicking HERE.

Top of page

Contaminants and Risks

Abandoned uranium mines (AUMs) pose several threats to health and safety in the form of physical hazards and potential exposure to associated contaminants. Physical hazards include, but are not limited to, shafts and pits that people might fall into or unstable debris piles such as waste rock piles or abandoned transfer piles that might slide or be treacherous to traverse. AUMs may have a variety of contaminants that can impact health. Uranium ore, heavy metals, and other materials or chemicals associated with mine operations are just a small set of the potential contaminants that can be present at AUMs. Each of the potential contaminants pose unique risks to human health.

Contaminants

Uranium
Uranium is a natural and commonly occurring radioactive element. It is found in very small amounts in nature in the form of minerals. In the geologic formations that underlie the Navajo Nation uranium is more concentrated. In its natural state uranium ore does not impact the people who live on the surface of the geologic formations because the rock acts as a shield that blocks the harmful effects of the uranium. Uranium has three primary routes or pathways that can impact human health: inhalation, ingestion, and direct exposure to radiation. (For more information about the health affects or uranium click here.)

Uranium ore concentration and associated radioactivity varies widely at mining areas and natural formations across the Navajo Nation. EPA is evaluating the likelihood for offsite migration due to historic mining activities.

Because of the slow rate of decay, the total amount of natural uranium in the earth stays almost the same, but it can be moved from place to place through natural processes or by human activities. When rocks are broken up by water or wind, uranium becomes a part of the soil. When it rains, the soil containing uranium can go into rivers and lakes. Mining, milling, manufacturing, and other human activities also move uranium around natural environments.

During the decay processes, the parent uranium-238, its decay products, and their subsequent decay products release a series of new elements and radiation, including radium and radon, alpha and beta particles, and gamma radiation. Alpha particles cannot pass through human skin, whereas, gamma radiation passes through more easily.

Radioactive Contamination
What is Radioactivity?
Radioactivity is the property of some atoms that causes them to spontaneously give off energy as particles or rays. Radioactive atoms emit ionizing radiation when they decay. When radioactive atoms decay three forms of energy are emitted: Alpha, Beta, and Gamma.

o Alpha Particles: The alpha particle is a type of ionizing radiation. The health concerns associated with Alpha particles are inhaling dusts that are Alpha emitters. Once Alpha emitting dusts are inhaled, they can become lodged in the lungs and the energy from the Alpha particles can cause damage to lung tissue. This is further enhanced by prolonged exposure to Alpha emitting dusts. Alpha is not a significant concern for external exposure, human skin is often sufficient to block Alpha particles.

o Beta Particles: Beta particles are subatomic particles ejected from the nucleus of some radioactive atoms. The health concerns associated with Beta particles are issues of proximity to Beta emitting sources. It is the excess energy or the speed of the Beta particles that causes damage to living cells and tissue. Prolonged exposure to Beta emitting sources enhances health risks. *NOTE* Uranium is not a significant Beta emitter

o Gamma Rays: Gamma rays travel at the speed of light and exist only as long as they have energy. Once their energy is spent, whether in air or in solid materials, they cease to exist. The same is true for x-rays. The health concerns associated with Gamma rays are issues of proximity to Gamma emitting sources. Gamma and x-rays can easily travel great distances through air and penetrate several centimeters in tissue. Although they are generally classified as an external hazard; gamma emitting radionuclides can also be inhaled, or ingested with water or food, and cause exposures to organs inside the body.

o Radon: Radon is a radioactive gas. It comes from the natural decay of uranium that is found in nearly all soils. It typically moves up through the ground to the air above and into the home through cracks and other holes in the foundation. The home traps radon inside, where it can build up. Any home may have a radon problem. This means new and old homes, well-sealed and drafty homes, and homes with or without basements. Radon from soil gas is the main cause of radon problems. Sometimes radon enters the home through well water. In a small number of homes, the building materials can give off radon, too. However, building materials rarely cause radon problems by themselves. (For additional information about Radon, please visit the US EPA’s ‘A Citizen’s Guide to Radon’)

For more information about understanding radiation click here
(http://www.epa.gov/rpdweb00/understand/index.html)

How are people affected by radioactive contamination?
Radioactive contamination occurs in three forms:
1. Inhalation – Breathing in dust particles that have radioactive properties or radon gas
2. Ingestion – Eating or swallowing dust particles that have radioactive properties
3. Direct Exposure – Living or being in close proximity to Gamma rays
(For more information about the health affects or uranium click here.)

How is radiation contamination associated with AUMs?
Soils
Waste rock and un-merchantable ore is often cast aside or placed in waste piles. This material can be used as aggregate for concrete or used as whole rock as a building material for traditional Navajo hogans. When this radioactively contaminated material is used as a building material at a home site, exposure becomes a chronic concern. Dusts that eroded from the concrete floors and rock walls are Alpha emitters that can become inhaled on a daily basis. The materials themselves can be Gamma emitters that expose residents to Gamma rays on a daily basis. Radioactively contaminated soils can also be ingested (swallowed). Ingestion can happen many different ways. Wind may blow dusts onto food about to be consumed. Wind may blow dusts directly into the mouth. Dusts may not be sufficiently washed off produce that was grown in close proximity to radioactively contaminated soils. Radioactively contaminated soils may be ingested by livestock that is later consumed after slaughter; this is especially problematic when organ tissue is consumed because radiation and other contaminants are concentrated in the organs.

Water
Water is equally erosive as wind. As water erodes waste rock or un-merchantable ore, those radioactively contaminated sediments can be held in suspension within the water. The same is true in groundwater. Water can dissolve uranium within the aquifer and suspend the radionuclides. Those suspended, radioactively contaminated particles are easily ingested (swallowed) by humans and live stock. Water also has the capacity to transport radioactively contaminated sediments to bodies of water that may be used as stock ponds or swimming holes. Much the same as radioactively contaminated soils contribute the accumulation of radioactive contaminants in the body, water borne radioactively contaminated particles are a health concern.

Heavy Metals
There are other heavy metals associated with AUMs such as Arsenic and Lead.

For more US EPA information about Arsenic, please click here.

For information about health affects associated with Arsenic, please click here.

For more US EPA information about Lead, please click here.

For information about health affects associated with Lead, please click here.

Other Potential Contaminants
There may be other contaminants at AUMs associated with mining operations. These contaminants could range from chemicals associated with heavy equipment operations such as fuels, solvents and degreasers, residues from blasting agents used in hard rock mining, or any other number of contaminants associated with day-to-day mine operations. In order to adequately identify contaminants of concern at a particular mine site, a thorough site evaluation will be necessary.

Top of page

Who is Involved

EPA lead on this Site Assessment Project in consultation with the Navajo Nation Environmental Protection Agency (NNEPA). Navajo Abandoned Mine Lands Program (AML) and the US Army Corps of Engineers are also important Partners.

FUTURE ACTIONS: Foreseeable actions will include:
(i) USEPA will survey approximately 100 structures and yards in Winter 2007 identified by Navajo Nation EPA studies. Decide whether to take action to mitigate risks posed to occupants.
(ii) USEPA will sample approximately 70 unregulated water sources possibly used for human consumption identified from prior field work and through the efforts of other regulators and non profit organizations.
(iii) USEPA will complete Northeast Church Rock Engineering Evaluation/Cost Analysis and make a decision by Summer 2008
(iv) USEPA will initiate activities at several other mine areas identified through past investigations, to determine whether Superfund removal actions and/or Superfund listing is appropriate to address site related risks,
(v) USEPA and NNEPA will continue to perform community outreach to the Navajo Chapters about the AUMs, as well as other areas that request community involvement relating to AUM issues. NNEPA is delivering copies of the Assessment Report, Atlas and GIS database to all 110 chapters.

Top of page

Investigation and Cleanup Activities

Completion of Assessment: In August 2007, USEPA, with support from NNEPA, AML and USACE, produced the Navajo Nation Screening Assessment Report and Atlas of all known abandoned uranium mine sites. The desktop assessment utilized existing AUM data to create a powerful GIS database identifying 520 mines. At the discretion of NNEPA, USEPA may conduct additional site-specific studies where there appears to be elevated health risks related to AUMs. USEPA will consult with NNEPA, before making potential response decisions.

With respect to future work, EPA and NNEPA will coordinate closely with the Navajo Abandoned Mine Lands Reclamation Program (AML). AML is a Navajo agency that reclaims AUMs with Surface Mining Control and Reclamation Act (SMCRA, 1977) authority and funding.

Aerial Surveys: The study entailed 41 aerial surveys of 33 Navajo Chapters, which encompass over 1,100 square miles, to identify sources of radiation (i.e., AUMs and naturally occurring deposits) followed by field sampling of possible mine features, potential drinking water sources and homes in the vicinity of radiation sources.

Residences: EPA is concerned about traditional Navajo hogans constructed of uranium ore, as well as contaminated soils in the vicinity of homes. Upon completing the aerial surveys, EPA notified communities in the vicinity of radiation sources that we could survey homes. This led us to sample 28 structures of which, two hogans were found to pose unacceptable health risk due to radiation exposure, notably gamma and radon levels. USEPA and NNEPA are currently surveying homes and are developing a strategy to conduct a comprehensive survey of contaminated structures to determine how widespread the problem may be.

Water: Ingestion of contaminated water has been identified as the exposure pathway of greatest concern. EPA sampled 226 water sources in the vicinity of radiation sources for uranium and other contaminants of concern, of which, 38 water sources were found to pose elevated health risks for radionuclides. Elevated health risks were only associated with unregulated water sources such as stock tanks, wells and springs. However, they were identified as drinking water sources by Chapter officials as sources used for drinking water by people that did not have running water. Elevated uranium was the primary contaminant of concern which might be linked to AUMs. In addition, some water sources were found to pose elevated health risks due to lead plumbing and biological hazards. In January 2000, Navajo EPA (NNEPA) asked EPA to pause field work until they could review our data and make recommendations about next steps. In February 2008, USEPA will resample the 38 sources as well as additional sources in the Eastern Agency not yet sampled.

Top of page

Cleanup Results to Date

Superfund Removal Actions:
Hogans: In October 2000, NNEPA asked EPA to remove two radioactive structures (hogans) in the Oljato (Monument Valley) and Teec Nos Pos (Four Corners) chapters. EPA negotiated with the families for several months to conduct the work and compensate them for replacement of the structures. EPA completed the removal actions in April 2001.

Northeast Church Rock Mine Site: In May 2007, USEPA conducted two removal actions involving excavation and backfilling of radium contamination in four yards adjacent to the mine Site. USEPA is completing the Engineering Evaluation/Cost Analysis for the mine site. USEPA intends to decide on a remedy by Summer 2008.

Top of page

Potentially Responsible Parties

Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.

Investigations of the former mine leasees and operators are on-going.

Top of page

Documents and Reports

Top of page

Community Involvement

Public Meetings: In March 2001, EPA formed a team of Navajo health, environmental and education agencies to plan and conduct an intensive 10-week round of outreach to the 30 Chapters where water samples were collected. The outreach consisted of discussing the water data and how to reduce exposure. Presentations were frequently in the Navajo language and reached approximately 1000 people. EPA developed chapter specific maps, indicating the water sources sampled, pictures of the source (e.g. well, spring, etc.) and the relative risk of drinking the water. The Uranium Education Program at Diné College/Shiprock provided translations and extensive background material about the AUMs. NNEPA and AML provided information about their programs to address the AUM issues.

EPA has since participated in additional community sampling and outreach activities organized by the Navajo Nation and individual chapters including Cameron (Black Falls area), Kayenta and Church Rock.

Northeast Church Rock Mine - USEPA and NNEPA have held three formal meetings and several informal meetings with residents and nearby interested neighbors.

Top of page

Public Information Repositories

Top of page

Additional Links

Top of page

Contacts

Top of page