Nuclear - Energy Policy Analysis: A Conceptual Framework - page 41

threaten people and the environment after shutdown of the mine, due to their release of radon gas
and seepage of water containing radioactive and toxic materials. In some cases uranium has been
removed from this low-grade ore by heap leaching. This may be done if the uranium content is
too low for the ore to be economically processed in a uranium mill. The leaching liquid (often
sulfuric acid) is introduced at the top of a tailings pile and percolates down until it reaches a liner
below the pile, where it is caught and pumped to a processing plant. This method entails potential
for extreme damage to the surrounding environment, especially surface and ground waters, and
must be carefully managed and monitored.
Surface mining of uranium entails environmental impacts similar to surface mining of coal, as
described extensively in Chapter 2. It affects air quality, water supply and quality, wildlife, vegeta-
tion, land use, soils, topography, and geologic and historic resources. As with coal surface mining,
what becomes of the land surface after uranium mining is determined by the manner in which
mining is conducted and reclamation implemented. Depending on the specific geologic strata and
location, uranium is found in ore with a wide variety of other minerals and heavy metals, many
of which are carcinogenic or toxic to humans, such as fluorine, lead, mercury, arsenic, cadmium,
copper, nickel, and chromium. These materials may contaminate dust and surface water in and
near uranium mines, at mills, and in tailings deposits (USBLM 1997; USNRC 1997).
Exposure to air- and water-borne dust and radiation from uranium mill tailings has been as-
sociated with high rates of leukemia, lung cancer, bone cancer, spontaneous abortions, premature
births, a variety of birth defects including broken chromosomes and mental retardation, impaired
kidney function, and chronic diarrhea (Wasserman and Solomon 1982; USNRC 1980, 1981; Jacobs
and Dickson 1979; Dreesen 1978; USGAO 1978, 1979). This is a much greater risk to workers in
underground mines than in surface mines, but also affects nearby residents. Noise, vibration, and
structural damage due to blasting continue to impose costs on some uranium mining operations
in the United States today.
From 1944 to 1986, nearly 4 million tons of uranium ore were extracted from Navajo lands
under leases with the Navajo Nation. Many Navajo people worked the mines, often living and
raising families in close proximity to mines and mills. Today the mines are closed, but a legacy
of uranium contamination remains, including over 500 abandoned uranium mines, and homes
and drinking water sources with elevated levels of radiation. Potential health effects include lung
cancer from inhalation of radioactive particles, bone cancer and impaired kidney function from
exposure to radionuclides in drinking water (USEPA 2011a, 2011b). A statistically significant
subset of these early miners later developed small-cell carcinoma after exposure to uranium ore
(Gottlieb and Husen 1982). Since 1994 the EPA has used its Superfund authority working with
the Navajo Nation EPA to assess 250 high-risk sites for further evaluation and has conducted
screening-level review and site visits of an additional 452 abandoned uranium mine sites, with
more detailed assessments to be completed at up to thirty-five mines, to identify appropriate courses
of action for the highest-priority mines. The EPA also completed a removal action to clean up
mine waste at Skyline Mine and an interim removal action at the Northeast Church Rock Quivira
Mine (USEPA 2011a, 2011b). Due to concerns over such health effects, and especially concern
for protecting groundwater drinking water supplies from contamination, the Navajo Nation tribal
government in 2005 adopted legislation banning uranium mining and processing on tribal lands
in Arizona (Navajo Nation 2005).
Groundwater supplies may be adversely affected by surface mining of uranium as with surface
mining of coal. On tailings piles where low-grade uranium or leaching chemicals are present, in-
creased infiltration may contaminate both groundwater and nearby streams for long periods. Lakes
formed in abandoned surface mining operations are more likely to be toxic if there are contaminants