Unittd Stales Eattem ErmiroomeolaJ B»A 520/1-83-007
Environment* Protection Radiation Facility June 1903
Agency P O Bex 3009
Office of RatfiBtion Program* Montgomery. AL 36193
Radiation ~
Potential Health and
Environmental Hazards of
Uranium Mine Wastes
Executive Summary
Report To The Congress
Of The United States
f
i
Volume 1 of 3 Volumes
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EPA 520/1-6-83-007
POTENTIAL HEALTH AND ENVIRONMENTAL
HAZARDS OF URANIUM MINE WASTES
Executive Summary
A Report to the Congress of the United States
in Response to Public Lav/ 95-604
June 10, 1983
U.S. Environmental Protection Agency
Office of Radiation Programs
Washington, D.C. 20460
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CONTENTS
SECTION
I INTRODUCTION 1
Purpose of the Report 1
Contents of the Report 1
Scope of the Report 3
Brief Description of Uranium Mining Operations 6
II ACTIVE MINES 8
Number of Mines 8
Health Impact of Air Emissions 8
Health Impact of Water Emissions 10
Health Impact of Solid Wastes 12
III INACTIVE MINES 14
Number of Mines 14
Health Impact of Air Emissions 14
Health Impact of Water Emissions 16
Health Impact of Solid Wastes 16
IV CONCLUSIONS AND RECOMMENDATIONS 19
Conclusions 19
Recommendations 22
V OTHER FINDINGS 23
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SECTION I
INTRODUCTION
PURPOSE OF THE REPORT
Uranium mining operations release some radioactive materials
into both air and water and generate large quantities of solid
v/astes containing low levels of radioactive materials. Solid wastes
produced by past mining operations remain on the surface at many
inactive mining sites, and represent a potential health and
environmental hazard similar in concept to uranium mill tailings.
Contamination of surface and subsurface water supplies also
represents a potential problem. To evaluate these potential
problems, the Congress, in Section 114(c) of the Uranium Mill
Tailings Radiation Control Act of 1978 (UMTRCA), instructed the
Administrator of the Environmental Protection Agency (EPA) to
prepare a report "which identifies the location and potential
health, safety, and environmental hazards of uranium mine wastes
together with recommendations, if any, for a program to eliminate
these hazards."
This report analyzes the potential health and environmental
impacts of both active and inactive uranium mines, lists the
locations of these mines, identifies additional information needs,
and recommends needed actions.
CONTENTS OF THE REPORT
This Executive Summary contains a brief description of the
material presented in the main text, including the principal
findings, conclusions, and recommendations. The full report
consists of this Executive Summary, a main text, and appendices.
The full report has been reviewed by the uranium mining industry,
States and the Nuclear Regulatory Commission. Comments have been
incorporated where possible.
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The Agency could not assess the environmental impacts of uranium
mining on a site specific basis because of a lack of adequate time
and data. Instead, we have done a generic assessment to develop an
overview of the regional impacts of the industry. We believe this
assessment to be fully responsive to the concerns which initiated
this request to the Agency, and to adequately evaluate the regional
environmental impacts of the uranium mining industry in the United
States.
This assessment is based on mathematical models of
representative (average) facilities, classed by type and size of
operation. Such models do not necessarily correspond with the
operation of any specific individual mine, and the assessments of
environmental impacts should not be associated with releases from
any particular mine. Such an analysis can present a composite
picture, and can be useful in determining if there is a need for
actions on a national scale.
In making this assessment, we have generally used realistic but
conservative parameters which tend to overestimate the potential
environmental impacts. This was done deliberately, with the intent
of putting an upper bound on the possible impacts. As a result some
mining operations may cause substantially lower impacts than is
indicated in this report. Therefore, this study should not be used
to assess the potential environmental impacts of any specific mine,
and it should be recognized that there is a wide diversity within
the industry. Use of the results of this study should be limited to
the purpose for which they were developed.
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Main text
The main text consists of seven chapters covering the following
subject matter:
--a general description of uranium mining
—an inventory of both active and inactive uranium mines
--sources and amounts of pollutants released to the
environment
--amounts of solid waste generated
--pathways of human exposure to pollutants
--health risks and environmental impacts
--recommendations and conclusions
Appendices
The appendices cover the following subjects:
--a detailed listing of the active and inactive
uranium mines in the United States and their
locations
--observations of existing conditions at
selected inactive mines
--a description of the methodology used in the health
risk and environmental impact assessments
SCOPE OF THE REPORT
This report addresses potential health impacts caused by
air and water emissions and solid wastes at active and inactive
underground and surface mines. We emphasize radiological impacts
because we believe these to represent the most significant health
hazards although nonradiological aspects of ground water and air
contamination were also studied. Impacts from other mining
activities, such as exploration, site preparation, and in situ
leaching, were evaluated in proportion to their potential
significance and the amount of available information about them.
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Pathways of Exposure
Underground and surface mining release radioactivity and
chemicals into air and water and generate solid wastes that may
spread through wind and water erosion and release radon-222 into
air. We have examined the extent to which people may be exposed to
these released materials or residual solid wastes and thereby incur
an increased chance of cancer or other health effects from:
—breathing air containing radon daughters,
—drinking water containing uranium and its daughters,
--eating food contaminated by either air or water, and
—living in homes on land covered by mine wastes.
Estimates of the health risks from each of these pathways are
presented in this report.
Method of Analysis
Our preliminary evaluations indicated little actual
environmental data is available to evaluate the impacts of releases
from uranium mines. Therefore, we developed models of active and
inactive mines using the available data and evaluated these impacts
on a broad generic basis. To the extent possible, operating
parameters and pollutant release rates characteristic of the various
classes of mines were used in our models. Finally we extrapolated
the health risks from the model mines to obtain an estimate of the
total health effects from all active and inactive mines on regional
populations within 50 miles from each mine. We estimate the risk to
the total U.S. population is no greater than a factor of 3 or 4
higher than our estimates for regional populations.
The availability of information to assess the health and
environmental impact from uranium mines varied greatly depending
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upon the type of release and pathway of exposure. In some cases, we
had to assume the most appropriate values to use in the analyses.
For some release-pathway combinations, we were able to make a
quantitative risk assessment. For other release-pathway
combinations, the information was so limited that we could identify
only the potential for impact.
We have expressed the health and environmental impacts in this
report in a number of different ways:
--Estimates of the risk of cancer to individuals
and to population groups
--Estimates of the risk of genetic effects to
the descendants of exposed individuals and
population groups
--Estimates of radioactiviy and chemical concentrations in
the environment and a comparison of these
concentrations with air or water standards or with
existing background levels
--Estimates of land areas disturbed, amounts of
solid wastes generated, quantities of water
discharged, and quantities of contaminants
released to air and water
--Qualitative observations of a potential health
impact
It must be recognized that the primary effect of radiation exposure
is cancer although genetic effects are also evaluated.
Uncertainty of Health Risk Estimate
To assess the increased chance of cancer and of genetic effects
occurring after exposure to radiation, Federal agencies base risk
estimates on studies of persons exposed at high doses and assume
that the effects at lower doses will be proportionately less. Such
assessments are based on a statistical'risk to all persons in a
large population exposed to a known radiation dose. Because of
uncertainties in the health risk analyses presented in this report,
these estimates should be used carefully.
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BRIEF DESCRIPTION OF URANIUM MINING OPERATIONS
The two major mining methods used in the United States are
underground and surface (open pit) mining. During 1978, underground
mines produced 5.5 million metric tons of ore containing 8300 metric
tons of uranium oxide (U308) while surface mines produced
7.5 million metric tons of ore containing 8700 metric tons
of U-jOg. In situ leaching, heap leaching, and mine water
extraction methods accounted for the remaining 1300 metric tons of
UgOg production.
Underground Mining
Underground mining uses shafts and tunnels to gain access to
the ore. A mine may extend underground for a mile or more at
several depths. The ore is moved to the surface and stored for
transport to a uranium mill. Waste rock and sub-ore* generated
during mining are also stored at the surface as a waste pile. At
most underground mines, these wastes remain on the surface when
mining ceases.
Large capacity ventilation systems are used at underground
mines to keep the radon-222 decay product concentrations in the
working areas below occupational exposure limits. Air is usually
forced down through the main shaft along the tunnels to the working
areas and then exhausted through ventilation shafts. Large
underground mines may have as many as a dozen ventilation shafts.
However, while ventilation removes radon-222 decay products from the
working areas, it discharges radon-222 to the atmosphere.
*Sub-ore contains uranium at a concentration uneconomical to mill.
This concentration varies with the "cutoff level" of the mill
receiving the ore. The cutoff level is usually determined by the
cost of milling vs. the value of the recovered uranium.
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Surface Mining
Surface mining is done by excavating one or more pits. The top
soil and overburden above the ore are removed and stockpiled. The
uranium ore is then removed and stockpiled for shipment to a uranium
mill. Sub-ore is also removed from the pit during these operations
and stockpiled for possible future use.
The present practice at most surface uranium mines is to
backfill the mined out pits with overburden as part of a reclamation
program. However, even though backfilling is performed, some waste
remains on the surface after mining is completed, and the final pit
may not be backfilled. Most older inactive mines were not
backfilled and little or no reclamation was done.
Mine Dewatering
Since most uranium ore deposits are below the water table,
groundwater must be controlled to prevent mines from flooding.
Underground mines and most surface mines are dewatered to allow for
excavation or shaft sinking and ore removal. Both underground and
surface mines discharge this water to natural surface drainage
systems. The discharged water, if necessary, is treated with barium
chloride and allowed to settle to reduce radium and suspended solids
before it is released. In addition to local effects, the long-term
impacts on regional water availability and quality are also
important considerations.
Exploratory and Development Drilling
The uranium industry has drilled approximately 1,300,000
exploratory and development drill holes through 1977. It appears
from mine site surveys and aerial photography that very few drill
sites have been reclaimed. Some States do require backfilling of
drill holes.
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The average drilling depth has increased with time and will
probably continue to do so in the future. Deeper drilling will tend
to increase the possibility that aquifers with good quality water
may be degraded by being connected, via the drill holes, with
aquifers of poorer quality water.
SECTION II
ACTIVE MINES
NUMBER OF MINES
In 1978 there were about 340 active uranium mines in the United
States. A list of these mines is presented in Appendix E and
includes the type of mine, location, and owner. Table 1 summarizes
the locations, numbers, and types of active mines:
Table 1
Location of Active Mines in United States in 1978
Other
4
3
1
3
2
0
Total 60 256 11 13
HEALTH IMPACT OF AIR EMISSIONS-ACTIVE MINES
Radiological Impacts
Exposure to radionuclide emissions into air from active uranium
mines increases the chance of cancer. These risks of cancer are the
State
Colorado
New Mexico
Texas
Utah
Wyomi ng
Other
Surface
5
4
16
13
19
3
Underground
106
35
0
108
6
1
In situ
0
0
8
0
3
0
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primary public health impact from air emissions due to active
uranium mines. Individuals who might be living near uranium mines
are exposed to higher radiation risks than those farther away. Our
estimates of potential impacts are based on model mines in the
absence of adequate field data. For our model of a large
underground mine we estimate that individuals living for a lifetime
1 mile from the mine would have an increased chance of fatal lung
cancer of 2 in a thousand resulting primarily from breathing
radon-222 decay products. The increased risk caused by the mine to
an individual living 25 miles away is several hundred times lower.
Risks from other types of uranium mines are somewhat lower.
We estimated the health impact from all active uranium mines
operating in 1978 by multiplying the risks from the model mines by
the number of active mines of each type. This procedure provides
only a very rough estimate of the total population risks from all
mines and is accurate only to the extent the model mine represents
an average for all operations. Based on this rough extrapolation of
the total risks from all mines, we estimate that the radionuclide
emissions into air from all active uranium mines operating in 1978
would cause less than one fatal cancer in the regional population
living around these sites.
The risk of genetic defects in future generations due to
airborne radiation exposure from uranium mines is very small
compared to the natural occurrence of hereditary disease. The
largest potential increase in genetic defects would occur near large
surface mines. Exposure of the population near a large surface mine
for one year is estimated to result in a very small chance of
additional genetic effects to their descendants (less than 0.0001
such effects in the population).
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Nonradiologi'cal Impacts
We estimated the air concentrations of nonradioactive
pollutants produced by our model mines at an assumed location of the
nearest individual—1 mile from center of mine site—and determined
the following emissions presented minimal potential risk to the
population:
--airborne stable trace metals
—airborne combustion products from heavy equipment
operation
--nonradioactive gas emissions at in situ leach mines
However, the estimated concentrations of particulates in the form of
dust in ambient air near large surface mines exceeded the national
ambient air quality standard. Most dust near active surface mines
is caused by vehicle traffic.
HEALTH IMPACT OF HATER EMISSIONS-ACTIVE MINES
Radiological Impacts
The health risks due to radionuclide emissions to water from
active uranium mines are lower than those caused by radionuclide
emissions to air. Although we were able to estimate cancer risks
caused by radionuclides in discharged water from our model
underground and surface mines, we could not do so for in situ leach
mines because of insufficient data. However, radionuclide releases
in water appear to be low from in situ mines. As with our estimates
of air emission impacts, models utilizing some actual data were used
to develop this information.
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For our model of an average underground mine, we estimated that
individuals living for a lifetime 1 mile from an underground mine
would have an increased chance of cancer of about one in a hundred
thousand due to releases to surface water. Ue estimated that about
one additional cancer in several hundred years might occur from the
normal controlled releases from these mines.
However, mine water discharged to nearby streams can recharge
shallow aquifers, many of which are presently used for drinking
water or may be in the future. We do not have enough information at
this time to evaluate the potential health risks from using these
aquifers, but using these aquifers for drinking water could result
in increased radiation exposure.
Where such a problem may exist, the state radiological program
should investigate existing records to determine the contaminant
levels in these aquifers due to mining, and evaluate the
significance of the health risks from using these shallow aquifers.
If a state determines that sufficient data do not exist to perform
an evaluation, additional sampling and analyses should be performed
by the state to acquire the necessary data.
Nonradiological Impacts
We estimated the concentrations of nonradioactive pollutants in
the streams used by the general population of the region from our
mine models. These concentrations were from dewatering the model
mines and were calculated after the discharge was diluted by the
receiving stream. Under these conditions, none of the pollutant
concentrations alone or in combination exceeded the EPA Water
Quality Criteria concentrations for use in irrigation and livestock
water. However, the recharge of shallow aquifers and the use of
these aquifers for drinking water present a potential problem
similar to that discussed for radionuclide emissions. Thus States
may want to evaluate pollution concentrations to ensure drinking
water standards are met.
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HEALTH IMPACT OF SOLID HASTES-ACTIVE MINES
Radiological Impacts
Uranium mining operations generate large quantities of solid
wastes containing low levels of radioactive materials. An average
surface mine generates about 6 million metric tons of solid waste
per year, while an underground mine generates considerably
less—about 20 thousand metric tons per year. These wastes consist
of sub-ore, waste rock, and overburden. At surface mines the
sub-ore comprises only a few percent of the waste while at
underground mines, because much less waste is produced, the sub-ore
may comprise up to 90 percent of the waste.
Through wind, water erosion, and release of radon-222, these
wastes can potentially contribute to air and water pollution. These
wastes pose this hazard because they contain elevated concentrations
of radium-226. Sub-ore (depending upon the cutoff grade for
milling) may contain up to 50 picocuries per gram (pCi/g) of
radium-226, and, even though the overburden and waste rock contain
lower concentrations of radium-226 than the sub-ore, large
quantities of these wastes can contain concentrations of radium-226
in excess of 5 pCi/g.* EPA has proposed that uranium mine wastes
containing radium-226 in quantities greater than 5 pCi/g be listed
as "hazardous wastes" under the Resource Conservation and Recovery
Act (RCRA) and has also proposed regulations for the treatment,
storage, and disposal of these wastes (43 FR 58946, December 18,
1978). The EPA is currently conducting an extensive study of solid
wastes from mines, including uranium mines at the request of
Congress. If warranted, further regulations on mining would be
promugated.
*The radium-226 concentration of most soil and rock is about 1 pCi/g.
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Use of Wastes in Building Construction
Using wastes containing elevated levels of radium-226 as land
fill for residential construction or building homes on land
contaminated by these wastes can greatly increase the chance of lung
cancer to individuals living in these structures. Radon-222 formed
from the decay of radium-226 is an inert gas that readily seeps
through foundations, floors, and walls and accumulates in the inside
air of a house. The radon-222 then decays to daughter products
which, when breathed, will lodge in the lungs and cause radiation
exposure to the lung tissues. For example, the use of uranium mill
tailings in the construction of homes in Grand Junction, Colorado,
resulted in radon-222 decay product concentrations inside the homes
that required a Federal-State remedial action program for the
affected structures (Public Law 92-314). These mill wastes,
however, contain much higher concentrations of radium-226 than mine
wastes. A survey of homes in Florida on reclaimed land containing
wastes from phosphate mining showed about 20 percent of these homes
have radon-222 decay product concentrations in excess of 0.03
working level (WL).* Lifetime residency in a home with this level
could increase the chance of lung cancer by as much as 4 in
100--thus doubling the normal risk of lung cancer.
The mechanisms by which uranium mine wastes may cause health
risks are similar to those which have occurred from uranium mill
tailings and phosphate wastes. Although uranium mine wastes usually
have a lower radionuclide content and are less suitable as a
construction material than the sand-like tailings, these wastes are
still a potential health hazard to individuals if effective waste
disposal methods are not used. EPA has provided to the States
survey reports of radiation anomalies that may be due to use of mine
wastes in construction and will continue to support State use of
this data.
*A working level (WL) is any combination of short-lived radon decay
products in one liter of air that will result in the ultimate
emission of alpha rays with a total energy of 130,000 MeV. The
working level expresses a concentration of radioactivity in the air,
not how much radiation a person receives. EPA estimates that the
average working level in U.S. homes is about 0.004 WL.
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SECTION III
INACTIVE MINES
NUMBER OF MINES
There are about 3400 inactive uranium mines in the United
States. A list of these mines developed from computer listings
maintained by the U. S. Department of Energy is presented in
Appendix F including the type of mine, location, and owner. The
following table summarizes the numbers and types of inactive mines
by State:
Table 2
Location of Inactive Mines in United States
State Surface Underground Other
Arizona 135 189 2
Colorado 263 902 52
New Mexico 34 142 12
South Dakota 111 30 0
Utah 378 698 17
Wyoming 223 32 10
Other 108 43 8
Total 1252 2036 101
HEALTH IMPACT OF AIR EMISSIONS- INACTIVE MINES
Radiological Impact
Radionuclide emissions into air at inactive mine sites are
small compared to the emissions from active mines according to our
estimates of model mines. The principal radionuclide emitted,
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radon-222, emanates from unsealed mine vents, portals and residual
waste piles. This causes only small increases in the risk of lung
cancer to individuals living near these mine sites. Utilizing the
same models as for the active mines, we estimated risks of cancer
from radon-222 emissions to air from our model inactive mines.
By multiplying the risks from our model mines by the number of
inactive mines of each type, we extrapolated the total number of
potential cancers from all inactive mines. This procedure provides
only a very rough approximation of the total risk from all inactive
mines.
By these estimates, radon-222 emissions from inactive uranium
mines would produce the following cancer risks:
Individuals living for a lifetime 1 mile from an inactive
mine would have an increased chance of lung cancer of
about 2-3 in 100,000.
The amount of radon-222 released each year from all
inactive uranium mine sites would cause about 0.1 lung
cancers in the regional population around these sites.
Nonradiological Impacts
We did not identify any significant health impact associated
with nonradiological air emissions at inactive uranium mines. Our
estimates of dust emissions from wind erosion of waste piles showed
that insignificant concentrations of nonradiological pollutants
would exist in air at these inactive sites.
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HEALTH IMPACT OF WATER EMISSIONS-INACTIVE MINES
The extent to which inactive surface and underground mines harm
water quality is poorly understood. Ground water in contact with
ore bodies and consequently in mines typically contains
radionuclides and trace elements, and the flow of the water away
from the site carries dissolved and suspended radionuclides and
trace elements.
Site specific studies are needed to determine the present and
potential impacts of inactive uranium mines on both surface and
groundwater quality. As with active mines, the potential exists for
contamination of drinking water supplies. States may desire to
conduct sampling of drinking water at a few sites in the vicinity of
inactive mining districts to provide data to evaluate whether such a
potential is valid.
HEALTH IMPACT OF SOLID WASTES-INACTIVE MINES
Surface Mines
We estimate that over 1 billion tons of solid wastes were
generated at surface uranium mines through 1978. These wastes
consist of sub-ore and overburden. The sub-ore, which may comprise
about 3 percent of the total wastes, contains significantly elevated
concentrations of radium-226 (up to 100 pCi/g).* Although the over-
burden contains much lower concentrations of radium-226 than the
sub-ore, large quantities of these wastes can contain radium-226 in
concentrations in excess of 5 pCi/g~the level EPA has proposed be
used to judge whether wastes should be considered as a candidate for
designation as hazardous waste under RCRA. Such a determination
would require that specified disposal methods be developed for these
mine wastes.
*The radium-226 concentration of normal soil and rock is about 1 pCi/g.
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In many surface mines opened since 1970, the general practice
is to backfill the mined-out pits with wastes as part of a recla-
mation program. However, at most older inactive surface mines,
little or no reclamation was done.
Underground Mines
We estimate that about 30 million tons of solid waste
consisting mostly of sub-ore were generated at underground uranium
mines through 1978. As in surface mining, the sub-ore contains
significantly elevated concentrations of radium-226 (up to
lOOpCi/g). There has been very little reclamation at inactive
underground mine sites, so most of these wastes remain on the
surface at these sites.
Use of Hastes in Building Construction
As discussed in the section on active mines, uranium mine
wastes would present a significant hazard to individuals if homes
are built on land contaminated by these wastes or if these wastes
are used in construction materials for homes. Individuals living in
these homes could have an increased chance of lung cancer from
breathing radon-222 decay products. The extent to which uranium
mine wastes have previously been used for these purposes is not well
known.
However, some information is available which shows that uranium
mine wastes may have been widely used as landfill in the
construction of various types of buildings. In 1972 EPA and the
former Atomic Energy Commission (AEC) tried to identify locations of
higher-than-normal levels of gamma radiation in an attempt to locate
uranium mill tailings. During this study, over 500 locations were
identified where uranium ore was believed to be the source of
elevated gamma radiation. Since it is unlikely that ore-grade
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material would be used as landfill, we suspect that uranium mine
wastes (perhaps sub-ore) may be the source of the abnormal gamma
radiation at these sites.
In order to better define the off-site use of uranium mine
wastes, EPA is studying the extent to which these wastes have been
used away from the mine sites for landfill or in construction
materials for use in homes. If mine wastes were involved in
construction of homes, a health risk from radon-222 emissions would
exist. A preliminary survey has already been completed and the
information has been shared with the interested agencies in
appropriate States.
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SECTION IV
CONCLUSIONS AND RECOMMENDATIONS
The evaluation of the potential impacts of uranium mining was
performed largely by means of analytical studies of model
facilities. We believe that the results give an adequate
representation of the industry. In order to determine the extent of
possible problems, our studies were specifically designed to give
conservative results. It should be recognized that actual mines may
operate under conditions producing substantially smaller impacts
than the results presented.
Compared to uranium milling, health and environmental effects
of uranium mining are not as well understood, despite the existence
of over 3000 active and inactive mines. We have noted throughout
this report instances of the absence or inadequacy of pertinent
information.
CONCLUSIONS
Solid Wastes
Solid uranium mining wastes are potentially hazardous to health
when used as building materials or when buildings are constructed on
land containing such wastes. The hazard arises principally from
increased risk of lung cancer due to radon-222. In a 1972 survey of
communities in uranium milling and mining regions, EPA and the
former Atomic Energy Commission found more than 500 locations where
such wastes had been used.
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Airborne Effluents
a) Individuals living very near active underground mine
exhaust vents would have an increased risk of lung cancer caused by
exposure to radon-222 emissions. Surface mines and in situ mines
are less hazardous, and inactive mines do not have significant
radon-222 emissions. Other airborne radioactive emissions from all
types of mines are judged to be smaller.
b) The number of additional cancers committed per year in
regional populations due to radionuclide air emissions from the
approximately 340 active mines and 3300 inactive mines was estimated
to be about 0.6 cancers in 1978. This number of estimated
additional cancers is small, about one-third of the estimated
additional cancers in regional populations due to radon emissions
from the 24 inactive uranium mill tailings piles addressed by Title
I of the Uranium Mill Tailings Radiation Control Act. (These mill
tailings piles represent about 13 percent of all tailings currently
existing due to U.S. uranium milling and mining). These potential
effects are not of sufficient magnitude to warrant corrective
measures, especially considering the large number of sites
involved.
c) The following emissions were judged to cause an
insignificant health risk at all types of mines:
1. airborne nonradioactive trace metals
2. airborne combustion products from heavy-duty equipment
operations
3. nonradioactive emissions from in situ leach sites
d) Airborne dust near large surface mines (primarily caused by
vehicular traffic) may exceed the National Ambient Air Quality
Standard for particulate matter.
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Waterborne Effluents
a) We estimate that an insignificant health risk accrues
currently to populations from waterborne radioactivity from an
average existing mine.
b) Uranium mine dewatering and water discharges, which are
increasing as more and deeper mines are created, may in the future
have significant effects on water quality. Current treatment
practices are controlling the release of radioactivity into surface
waters.
c) Water in inactive surface and underground mines usually
contains radionuclides and trace elements in concentrations
comparable to ground water in contact with ore bodies. Some
abandoned underground mines in certain areas of Colorado and Utah
probably discharge such waters to nearby streams and shallow
aquifers. Available data is not sufficient to conclude whether or
not there is a problem.
d) We could not determine, using models, that there is no
health hazard to individuals who drink water drawn from surface or
underground sources. Water discharges from active mines to nearby
streams and stream channels may extensively recharge shallow
aquifers, many of which are either now used or could be used for
drinking water. Such determinations must be made on a site-specific
basis, and take account of the additive effects of multiple mines.
These studies can be made easily a part of State or utility
surveillance programs.
Exploratory and Development Drilling
Harm from effluents due to exploratory and developmental
drilling is probably small compared to effects of operating mines.
Under current regulations and practices, however, aquifers
penetrated at different levels can mix, creating the potential for
degrading good quality groundwater.
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RECOMMENDATIONS TO CONGRESS
1) Based on this study, we do not believe at this time that
Congress needs to enact a remedial action program like that for
uranium mill tailings. This is principally because uranium mine
wastes are lower in radioactivity and not as desirable for
construction purposes as uranium mill tailings. Nonetheless, some
mining waste materials appear to have been moved from the mining
sites, but not to the extent that mill tailings were.
2) Some potential problems were found that might require
regulatory action, but none of these appear to require new
Congressional action at this time.
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SECTION V
OTHER FINDINGS
1) Regulations may be needed to control wastes at active
uranium mines to preclude off-site use and to minimize the health
risks from these materials. These regulations would need to address
the use of the materials for construction purposes as well as
ultimate disposal of the materials.
EPA proposed such regulations in 1978 under the Resource
Conservation and Recovery Act (RCRA). In 1980, Congress amended
RCRA to require further EPA studies before promulgating general
regulations for mining wastes. An EPA study by the Office of Solid
Wastes on all types of mines, including uranium mines, is currently
being conducted. The amendment does not affect EPA's authority to
regulate use of uranium mine wastes in construction or reclamation
of lands containing such wastes.
2) Standards are needed to control human exposure from
radioactive air emissions from uranium mines. This is principally
because of potential exposure to individuals living near large
underground uranium mines rather than concerns regarding the
exposure of regional populations. We have proposed such standards
under Section 112 of the Clean Air Act.
3) EPA has conducted two field studies in 1972 and 1978 which
define possible sites at which mine wastes may have been used in
construction or placed around buildings. The information developed
in these studies has been sent to State health departments. The
States should conduct follow-up studies, as appropriate, to
determine whether there are problems at these sites.
4) The adequacy with which NPDES permits protect individuals
who may obtain drinking water near the discharge points for uranium
mine dewatering should be evaluated by States. Under the Public
Water Systems provision of the Safe Drinking Water Act, radionuclide
standards now exist for drinking water.
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5) Some site specific studies should be considered by States
to determine the extent to which inactive uranium mines may be
significant water pollution sources.
6) States with uranium mines should determine the feasibility
of controlling fugitive dust from large surface mines and
incorporate the recommendations in State Implementation Plans.
7) States should require borehole plugs in drilling operations
that will prevent interaquifer mixing (exchange) and also seal
drilling holes at the surface.
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