United States
Environmental Protection
Agency
Office of
Radiation Programs
Washington DC 20460
EPA 520/4-82 01 ?1
October 1982
Radiation
Final
Environmental Impact Statement
for Remedial Action
Standards for Inactive
Uranium Processing Sites
(40 CFR 192)
Volume
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EPA 520/4/82/013-1
October 1982
Final
Environmental Impact Statement
for
Remedial Action Standards
for
Inactive Uranium Processing Sites
(40 CFR 192)
Volume I
Office of Radiation Programs
Environmental Protection Agency
Washington D.C. 20460
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VOLUME I
CONTENTS
SUMMARY xi
1. INTRODUCTION 1
2. HISTORY AND CURRENT STATUS OF THE INACTIVE URANIUM
MILLING SITES 3
2.1 Early History 3
2.2 The 1974 Congressional Hearings 4
2.3 Current Status of the Inactive Sites 5
3. RADIOACTIVITY AND TOXIC MATERIALS IN TAILINGS 15
3.1 Radioactivity in Tailings .- 15
3.2 Toxic Materials in Tailings 19
3.3 Offsite Contamination due to Natural Forces 19
3.4 Offsite Contamination Caused by Man 29
3.5 Indoor Radon Decay Product Concentrations due to
Natural Causes 36
4. RISKS TO HEALTH FROM URANIUM TAILIN3S 39
4.1 Introduction 39
4.2 Radon and Its Immediate Decay Products 41
4.3 Exposure Pathways 42
4.3.1 Indoor Exposure Due to Misuse of Tailings 43
4.3.2 Exposure to Radon Decay Products from Tailings
Piles 43
4.3.3 Exposure to Gamma Radiation from Tailings Piles,
Windblown Tailings, and Misuse of Tailings 47
4.3.4 Exposure to Radioactivity and Toxic Materials
from a Tailings Pile through Water and
Food Pathways 48
111
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CONTENTS (Continued)
4.4 Estimates of Health Risks from Radioactive
and Toxic Materials 52
4.4.1 Risk of Lung Cancer from Inhaling Radon
Decay Products 52
4.4.2 Cancer and Genetic Risks from Gamma Radiation 56
4.4.3 Risks from Toxic Materials 56
4.5 Estimated Effects on Health due to Tailings 58
4.5.1 Effects from Misuse of Tailings 58
4.5.2 Effects of Radon Emissions from Tailings Piles ... 59
4.5.3 Effects of Gamma Radiation Emissions from
Tailings Piles 63
4.6 Summary 68
5. METHODS FOR CONTROL OF TAILINGS PILES AND FOR CLEANUP
OF CONTAMINATED LANDS AND BUILDINGS 69
5.1 Objectives of Remedial Methods 69
5.2 Remedial Methods for Tailings 70
5.2.1 Stabilizing Tailings Piles 71
5.2.2 Preventing Radon Emissions 73
5.2.3 Controlling Direct Gamma Radiation 73
5.2.4 Protecting Groundwater Quality 75
5.2.5 Assuring Long-Term Control 77
5.2.6 Advanced Methods of Controlling Tailings 82
5.3 Remedial Measures for Buildings 83
5.4 Remedial Measures for Contaminated Lands and Offsite
Properties 35
5.4.1 Land Near the Tailirtgs Pile 85
5,4.2 Land Distant from the Tailings Pile 85
iv
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CONTENTS (Continued)
6. COSTS AND BENEFITS OF ALTERNATIVE STANDARDS FOR CONTROL OF
TAILINGS PILES 87
6.1 Alternative Standards for Control of Tailings Piles 87
6.2 Control Methods Selected for Each Alternative Standard .. 90
6.3 Costs of the Control Methods 93
6.4 Risks of Accidents When Carrying
Out Control Methods 93
6.5 Advanced Control Methods 96
6.6 Benefits Associated with the Alternative Standards 98
6.7 Summary of Benefits and Costs 101
7. COSTS AND BENEFITS OF CLEANUP STANDARDS FOR BUILDINGS
AND LAND CONTAMINATED WITH TAILINGS 105
7.1 Cleanup Standards for Buildings 105
7.2 Alternative Cleanup Standards for Near-site
Contaminated Land 107
7.3 Alternative Cleanup Standards for Offsite Properties .... Ill
8. SELECTING THE STANDARDS 115
8.1 Standards to Control Tailings Piles 116
8.1.1 Longevity of Control 116
8.1.2 Control of Radon Emissions 119
8.1.3 Protection of Groundwater Quality 122
8.1.4 Protection of Surface Water 126
8.1.5 Remedial Action for Existing Groundwater
Contamination 127
8.1.6 The Preferred Standard for Control of
Tailings Piles 128
8.2 Standards for Cleanup of Buildings 129
8.2.1 Previous Indoor Radon Standards 129
8.2.2 Indoor Radon 130
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CONTENTS (Continued)
8.2 Standards for Cleanup of Buildings (Continued)
8.2.3 Indoor Gamma Radiation 132
8.2.4 Preferred Cleanup Standard for Buildings 133
8.3 Standards for Cleanup of Land 133
8.3.1 Alternatives for Cleanup of Land 134
8.3.2 Preferred Cleanup Standard for Land 136
8.4 Supplemental Standards 137
9. IMPLEMENTATION 139
9.1 Standards Implementation Process 139
9.2 Effects of Implementing'the Standards 140
REFERENCES 145
GLOSSARY OF TERMS AND ABREVIATIONS 157
APPENDIXES
APPENDIX A: Standards for Remedial Actions at Inactive Uranium
Processing Sites A-l
APPENDIX B: Development of Cost Estimates B-l
APPENDIX C: Toxic Substances in Tailings C-l
TABLES
2-1 Number of Uranium Mill Sites by Year 6
2-2 Studies and Status of Inactive Mill and
Ore Processing Sites g
2-3 Summary of Conditions at Time of Phase I Site Visits 12
2-4 Summary of Phase I Findings 13
2-5 Recommendation from Phase I on Principal Actions to be
Studied in Phase II
3-1 Radioactivity in Inactive Uranium Mill Tailings Piles,
20
3-2 Average Concentration of Elements Found in Inactive Uranium
Mill Tailings 22
VI
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CONTENTS (Continued)
TABLES (Continued)
3-3 Elements Present in Tailings Sands and Slimes from an
Alkaline-Leach Mill 23
3-4 Estimated Area of Contamination at Inactive Mills 24
3-5 Elements Found in Elevated Concentrations in Groundwater
Near Tailings Sites 27
3-6 Location and Number of Gamma Radiation Anomalies—
1972 Survey 30
3-7 Indoor Concentrations of Radon Decay Products in Areas
Free of Tailings 37
4-1 Estimated Risk of Fatal Cancer from Lifetime Exposure to
Gamma Radiation at 100 mrem/y 57
4-2 Estimated Risk of Serious Genetic Abnormalities from
Lifetime Exposure of the Gonads to 100 mrem/y 57
4-3 Estimated Risk of Fatal Lung Cancer to Local and Regional
Populations Due to the Lifetime Exposure to the Radon
from Unstabilized Uranium Tailings Piles 60
4-4 Excess Risk of Fatal Lung Cancer Due to Lifetime Radon
Decay Product Exposure as a Function of Distance from a
Theoretical Tailings Pile 62
4-5 Estimated Risk of Fatal Lung Cancer Death Due to Radon for an
Assumed Lifetime Residence near Specific Tailings Piles.... 64
4-6 Lifetime Risk of Lung Cancer Due to Naturally-Occurring
Radon in Residential Structures 64
4-7 Risk of Fatal Lung Cancer to the U.S. Population Due to
Radon from Specific Tailings Piles 65
4-8 Risk of Fatal Lung Cancer to the U.S. Population Due to
Radon from All Inactive Tailings Piles 66
4-9 Risk of Fatal Cancers to Regional Populations Due to
Radionuclides from Inactive Tailings Piles 66
4-10 Radiation Exposure to Nearest Residents Due to Gamma
Radiation from Inactive Tailings Piles 67
4-11 Excess Risk of Fatal Lung Cancers Due to Radon from All
Inactive Uranium Mill Tailings Piles 67
vii
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CONTENTS (Continued)
TABLES (Continued)
5-1 Soil Erosion Rates in the United States 78
6-1 Alternative Standards for Control of Uranium Mill Tailings.. 88
6-2 Control Methods Selected for Each Alternative Standard 91
6-3 Estimated 1981 Costs of Control Methods for Two Model
Uranium Mill Tailings Piles 94
6-4 Estimated 1981 Costs for Controlling Uranium Mill
Tailings Piles 95
6-5 Estimated Accidental Deaths Associated with Alternative
Standards 97
6-6 Benefits Derived from Controlling Uranium Tailings Piles ... 99
7-1 Costs and Benefits of Alternative Cleanup Standards
for Buildings 108
7-2 Costs and Benefits of Alternative Cleanup Standards
for Land 110
FIGURES
3-1 The Uranium-238 Decay Series ............................... 16
3-2 Radon Production in a Tailings Pile ........................ 17
3-3 Distribution of Radon Decay Product Levels in
190 Contaminated Residential Buildings in
Grand Junction, Colorado .................................. 35
4-1 Radon Concentration Versus Distance From Tailings Pile
Center. Radon Emmission Rate is 20 pCi/m2s ............ 45
4-2 Excess Fatal Lung Cancer in Various Miner Groups by
Cumulative Exposure ...................................... 53
5-1 Percentage of Radon Penetration of Various Covers
by Thickness .............................................. 74
5-2 Reduction of Gamma Radiation by Packed Earth Cover ......... 76
Vlll
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CONTENTS (Continued)
VOLUME II
APPENDIX D: Response to Comments D-l
APPENDIX E: Letters of Comment and Testimony Submitted
at Oral Hearings E-l
IX
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SUMMARY
( ) Draft
(X) Final Environmental Statement
Environmental Protection Agency
Office of Radiation Programs
1. This action is administrative.
2. The Environmental Protection Agency is establishing standards
(40 CFR 192) for cleanup and long-term control of uranium mill
tailings at inactive mill sites that qualify for remedial actions
under the Uranium Mill Tailings Radiation Control Act of 1978
(PL 95-604). Sites are located in Arizona, Colorado, Idaho, New
Mexico, North Dakota, Oregon, Pennsylvania, Texas, Utah, and Wyoming.
These standards are issued to reduce and control the hazards
associated with uranium mill tailings. Two types of remedial actions
are required: cleanup of tailings that have spread from the original
site or have been removed for use elsewhere, and control to assure
environmentally sound long-term stabilization of the tailings.
These standards will be implemented by the Department of Energy
and affected States with the concurrence of the Nuclear Regulatory
Commission in consultation, as appropriate, with Indian Tribes and the
Department of Interior. The total cost is estimated to be
approximately $320 million (1981 dollars) over a period of seven years,
3. These standards have the following public health and
environmental benefits:
(a) Under the control standards, radon emission
rates from tailings piles will be reduced by
about 96 percent for at least 200 and up to
1,000 years. The measures used to achieve this
will prevent spreading of tailings by wind and
XI
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water erosion and should discourage misuse of
tailings by providing a significant barrier
against intrusion. With such controls, we
believe these tailings piles will not generally
threaten water quality, so we recommend
site-specific consideration of water protection
measures.
(b) Cleanup standards will require remedial actions
for buildings that have unusually high levels
of indoor radon and removal of tailings from
contaminated land when specified criteria are
exceeded. These actions will reduce or avoid
the public's exposure to significantly elevated
radiation levels from tailings.
4. The following alternatives were considered:
(a) No standards,
(b) Standards to provide minimum acceptable health
protection at the least cost,
(c) Standards to provide the maximum long-term
benefits relative to the cost, and
(d) Standards based primarily on nondegradation,
offering maximum protection with only moderate
consideration of cost.
EPA has selected alternative (c).
5. The following are the major points raised in public
comments on the proposed standards and EPA's resolution of
them:
(a) Estimated risk from radon—Some commenters
thought our estimates were too high. We
believe our risk estimates are reasonable, and
in any case, that uncertainties in these risk
estimates would not lead to different standards,
(b) Cost of the standards are high relative to
their benefits—Some commenters thought that
the cost of satisfying the proposed standard
was too high relative to the benefits. We
selected final standards that we believe will
provide nearly as great long-term benefits as
those we proposed, but at significantly lower
costs.
xii
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(c) Longevity of controls—Some commenters
suggested that 100-200 years of control would
be adequate and that institutional methods
should be used. We have selected final
standards designed for long-term protection
(many thousands of years) relying primarily on
physical control methods. We believe this was
the intent of Congress, is appropriate to the
nature of the potential hazard, and is
practical to achieve.
(d) Protecting groundwater—Commenters felt the
proposed numerical water standards were
inappropriate or unnecessary. The final
standards do not specify numerical limits for
radioactive and toxic materials in ground-
water. Rather, the implementing agencies will
site-specifically assess the potential for
future groundwater contamination and take any
appropriate action.
(e) The need for flexibility—Commenters argued
that the proposed standards were too close to
background levels for reasonable
implementation. The final standards are at
levels that are readily distinguishable from
background levels. This provides the
flexibility needed for unusual circumstances
and complications due to high natural
background leveIs.
6. The following Federal Agencies have commented on the Draft
Environmental Statement:
Department of Energy
Nuclear Regulatory Commission
Tennessee Valley Authority
Federal Energy Regulatory Commission
Department of Agriculture
Department of the Interior
Department of Health and Human Services
Department of Justice
7. This Final Environmental Impact Statement was made available to
the public in December 1982; single copies are available from the
Director, Criteria and Standards Division (ANR-460), Office of
Radiation Programs, U.S. Environmental Protection Agency, 401 M
Street, S.W., Washington, D.C. 20460, or National Technical
Information Service, 5285 Port Royal Road, Springfield, Va., 22161.
Xlll
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Chapter 1: INTRODUCTION
In enacting the Uranium Mill Tailings Radiation Control Act of
1978 (Public Law 95-604, 42 USC 7901), the Congress found that:
• "Uranium mill tailings located at active and inactive mill
operations may pose a potential and significant radiation
health hazard to the public, and that...
• "Every reasonable effort should be made to provide for the
stabilization, disposal, and control in a safe and
environmentally sound manner of such tailings in order to
prevent or minimize radon diffusion into the environment and to
prevent or minimize other environmental hazards..."
To these ends, the Act requires the Environmental Protection
Agency (EPA) to set generally applicable standards to protect the
public against both radiological and nonradiological hazards posed by
residual radioactive materials at the twenty-two uranium mill tailings
sites designated in the Act and at additional sites where these
materials are deposited that may be designated by the Secretary of the
Department of Energy (DOE) ' '. Residual radioactive material means
(1) tailings waste resulting from the processing of ores for the
extraction of uranium and other valuable constituents, and (2) other
wastes, including unprocessed ores or low grade materials, as
determined by the Secretary of Energy, at sites related to uranium ore
processing. We will use the term tailings to refer to all of these
wastes.
All but one of the 22 inactive mill tailings sites designated in
the Act are located in the western United States; the other is at a
former rare-metals processing plant in Canonsburg, Pa. The DOE has
designated two additional uranium processing locations as sites that
require remedial action. These are located near Bowman and Belfield,
North Dakota.
Act also requires EPA to set generally applicable standards
for tailings from active uranium mills. However, the standards
discussed in this FEIS do not address active mills.
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In this Final Environmental Impact Statement (FEIS), we examine
(1) alternative standards for disposal of uranium mill tailings
produced at the 24 designated sites, and (2) alternate standards for
cleaning up lands and buildings contaminated with tailings from these
sites. Nonradioactive toxic substances are also considered. In
developing this FEIS, we evaluated potential effects of tailings on
public health and considered the effectiveness and permanence of
different approaches to control those effects. We also developed cost
estimates for specific control options.
In Chapter 2 we summarize the history of the uranium milling
industry and briefly review information on the current status of the
designated sites. Chapter 3 contains a review of the radiological and
nonradiological characteristics of the sites and our estimates of how
much contamination there is in nearby land and buildings. Chapter 4
contains an analysis of the potential health hazards posed by uranium
mill tailings, including estimates of the risks to individuals living
close to the piles, to populations in the local region, and to the
population of the continental United States.
In Chapter 5 we examine the efficacy and longevity of the
principal methods for disposal and cleanup of tailings. In Chapter 6
we estimate costs and benefits for tailings piles control options and
discuss other significant factors such as duration and effectiveness of
controls and occupational hazards when controls are put into use.
Chapter 7 contains an examination of the costs and benefits for
specific alternatives for cleaning up contaminated land and buildings.
In Chapter 8 we review the results of Chapters 6 and 7 and show how
those results provide a basis for choosing standards. Chapter 9
contains a discussion of how these standards could be implemented and
the anticipated effects of such implementation.
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Chapter 2: HISTORY AND CURRENT STATUS OF THE INACTIVE URANIUM
MILLING SITES
2.1 Early History
The following brief history of uranium milling appeared in the
Nuclear Regulatory Commission's Final Generic Environmental Impact
Statement on Uranium Milling (NRC80). It summarizes lengthier papers
by Merritt (Me71) and by Facer (Fa76).
"In the past 35 years the uranium industry has undergone a
series of transformations, uranium changing almost overnight from
a commodity of only minor commercial interest to one vital for
nuclear weapons and, now, to its important peaceful use as a fuel
for generation of electrical energy. With each change there has
been a surge of interest in ore exploration and development and in
new and expanded production facilities.
"The military demand for uranium beginning in the early 1940s
had to be met from known sources of supply. The rich pitchblende
ores of the Shinkolobwe deposit in the Belgian Congo and the Great
Bear Lake deposit in Canada supplied uranium during the war years
and were supplemented by production from treatment of old tailings
dumps and a few small mines in the Colorado Plateau area. These
high-grade ores and concentrates were refined by an ether
extraction technique adapted from analytical procedures. Crude
ore milling processes for low-grade ores used during this period
reflected little change from methods used 40 years earlier (at the
turn of the last century) with uranium recovery from the leach
solutions based on several stages of selective precipitation.
Milling costs were high and overall recovery was low, as judged by
current standards.
"With passage of the Atomic Energy Act of 1946, a strong
emphasis was placed on the discovery and development of new
worldwide sources of uranium. At the same time, the research
efforts begun earlier were expanded in scope and magnitude to
advance the process technology. These efforts led to greater use
of lower grade ores than previously had been considered feasible,
such as the uranium-bearing gold ores in South Africa, as a source
of uranium, and to the discovery and development of large,
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low-grade deposits in the Beaverlodge, Elliot Lake, and Bancroft
regions of Canada.
"In the United States, prospecting and mining for uranium
were encouraged by the Atomic Energy Commission (AEC) through
guaranteed fixed prices for ore, bonuses, haulage allowances,
establishment of ore-buying stations and access roads, and other
forms of assistance. These incentives led directly to an increase
in the known mineable reserves of ore in the western United States
from about 9 x 105 metric tons (MT) (1 x 106 short tons (ST))
in 1946 to 8.1 x 107 MT (8.9 x 107 ST) in 1959. Programs also
were initiated to examine other possible sources of uranium and to
develop methods for processing these materials. AEC purchases
from 1948 through 1970 totalled approximately 3 x 10* MT
(3.3 x 105 ST) of U30g, of which nearly 1.6 x 105 MT
(1.8 x 105 ST) with a value of about $3 billion were supplied
from domestic sources...
"During the peak production years in the United States, from
1960 through 1962, the number of operating mills (excluding plants
producing by-product uranium from phosphates) varied from 24 to
26, with total annual production exceeding 1.5 x 10^ MT
(1.7 x 10^ ST) of U30g from the treatment of about 7 x 106
MT (8 x 106 ST) of ore.
"In 1957, it was apparent that very large ore reserves had
been developed, and that additional contracts, which were the main
incentive for exploration by potential producers, would lead to
commitments exceeding government requirements through 1966. In
1958, the AEC withdrew its offer to purchase uranium from any ore
reserves developed in the future. This led to shutdowns of mills
after expiration of contracts and to stretching out of deliveries
under long-term contracts in the United States, Canada, and South
Africa...
"Total production of U-jOg through 1979 from Ui S. sources
is estimated at about 2.75 x 105 MT (3.1 105 ST). The amounts
of ore used in the production of this ^Og, and the
approximate amount of tailings produced, were expected to reach
1.5 x 108 MT (1.6 x 108 ST) by the end of 1979. Of this
total, about 20%, or 2.5 x 10' MT (2.8 x 107 ST), is located
at inactive mill sites and the balance (80%) is located at
currently active mill sites..."
2.2 The 1974 Congressional Hearings
The hazards posed by mill tailings were not completely recognized
in the uranium industry's early years, and, while the Atomic Energy Act
of 1954 instituted licensing of mill operations, tailings remained free
of controls. Even though numerous .studies had assessed tailings
hazards and several Federal agencies and States (e.g., Colorado) had
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acknowledged a need for controls, a comprehensive control program was
not started until the late 1970's.
On March 12, 1974, the Subcommittee on Raw Materials of the Joint
Committee on Atomic Energy conducted hearings to discuss S. 2566 and
H.R. 11378, identical bills. The bills proposed that the U.S. Atomic
Energy Commission (later the Energy Research and Development
Administration and now the Department of Energy) and the State of Utah
jointly assess and act to limit public exposure to radiation from the
Vitro uranium mill tailings site at Salt Lake City, Utah.
EPA endorsed the bills' objectives but, with the AEC, recommended
instead that the two agencies, in cooperation with the states, assemble
comprehensive studies of all inactive mill sites. The studies would be
divided into two phases. Phase I studies would establish the sites'
condition, ownership, and surroundings and the need, if any, for more
detailed studies. Phase II studies would, as needed, evaluate the
hazards and analyze disposal alternatives and their costs.
Congress accepted this proposal. In May 1974, the Phase I studies
began (AEC74), followed by the first Phase II studies in 1975 (FB76-
78). All the studies were completed by 1978.
2.3 Current Status of the Inactive Sites
A typical inactive site contains the mill buildings where ore was
processed to remove the uranium, ore storage areas, and a tailings pile
covering approximately 50 acres. The tailings pile was usually made by
depositing slurried sand wastes on flat ground to form a pond into
which there was further deposition of slurried sand, finer grained
wastes ("slimes"), and process water. The water has since evaporated
or seeped into the ground, leaving a large pile of mostly sand-like
material. Some inactive sites also contain dried-up raffinate ponds,
special ponds where contaminated process water was stored until it
evaporated. Mill buildings, ore storage areas, and dried-up raffinate
ponds are usually heavily contaminated with radioactive material. The
amount of tailings produced by a mill is about equal in both weight and
volume to the ore processed, because the recovered uranium is only a
small part of the ore.
Table 2-1 shows the number of inactive uranium milling sites (and,
for comparison, active sites) at 5-year intervals. This listing omits
several small pilot facilities that produced uranium before 1950.
Table 2-2 lists all of the inactive uranium mill and ore
processing sites and indicates those included in the Phase I and Phase
II studies as well as those designated under the Act.
The Phase I Studies
The Phase I studies, completed during 1974, summarized conditions
at 21 of the inactive sites and outlined detailed engineering
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TABLE 2-1. NUMBER OF URANIUM MILL SITES BY
Year Inactive Active Total
Though 1940
1945
1950
1955
1960
1965
1970
1975
1980
0
1
1
2
4
13
20
24
25
4
5
9
12
30
21
15
15
22
4
6
10
14
34
34
35
39
47
(a)
v 'Jo77, Au70, and DOE81.
assessments to be performed later. Phase I excluded several inactive
sites: Monticello, Utah (owned by the Department of Energy); Edgemont,
South Dakota (owned by the Tennessee Valley Authority); Hite, Utah
(after high-grade tailings were removed, the site was covered by Lake
Powell which was created by the construction of the Glen Canyon Dam in
1963); Riverton, Wyoming (licensed by the AEC to a private owner at the
time of the Phase I studies, but later added to the Phase II studies);
Bowman, North Dakota; Belfield, North Dakota; Baggs, Wyoming; and
Canonsburg, Pennsylvania.
Following are four excerpts from the Phase I summary, covering:
(1) the Vitro site at Salt Lake City; (2) tailings stabilization; (3)
offsite radiation from tailings; and (4) the various uses that have
been made of inactive mill sites (AEC74). These provide examples of
conditions found at the inactive uranium mill sites.
The Vitro Site. Salt Lake City
"The existing conditions at the Vitro site in Salt Lake City
are completely unsatisfactory. The tailings pile, located at the
center of population of Salt Lake valley, is largely uncovered and
subject to continuing wind and water erosion. While the extent of
exposure of the population to radiation from this source may be
difficult to quantify, the spread of radioactivity is readily
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detectable for considerable distances offsite. Because of the
continued industrial growth in the area, the population exposure can be
expected to increase. The site is only partially fenced and is readily
accessible to the public. If the tailings pile were to be stabilized
by covering and vegetation at the present site, their integrity would
be difficult to maintain. While contamination of surroundings from
blowing dust could be reasonably well controlled, the emanation of
radon gas and leaching of radium into ground waters would be expected
to continue. The representative of AEC, EPA and the State of Utah
concur that the present site is unsuited to long-term radioactive
tailings storage, and the Phase II study of the Vitro site should be
directed principally toward a plan for removal to a more suitable
location.
Tailings Stabilization
"Tailings stabilization at six sites had not been attempted
at all. However, following the site visit, the State of Oregon
notified the owner that stabilization should be undertaken as soon
as possible at Lakeview. The chemical surface coating used at
Tuba City, Arizona, has broken up after only a few years
weathering and is considered unsuccessful. The conditions at
Shiprock, New Mexico, on the Navajo Reservation have been
considerably aggravated as a result of the operation of a heavy
earth-moving-equipment school on the site. The State of Colorado
adopted regulations in 1966 for stabilization and control of
uranium mill tailings by the mill owners. The substantial efforts
made in that state have been fairly successful. In no case,
however, was it found that the results could be considered
entirely satisfactory. Some erosion and loss of cover was noted
in all cases, and the vegetation was generally not self-sustaining
without continued maintenance, usually including watering and
fertilization. Thus, the stabilization work done to date
represents a holding action, sufficient for the present, but not a
satisfactory answer for long-term storage.
Offsite Radiation
"The mechanisms known to cause spread of radioactivity from
the sites are:
1. Windblown solids.
2. Radon gas and its decay products.
3. Deliberate removal of tailings and other materials for offsite
use.
4. Water erosion and dissolution.
5. Ground water and soil contamination.
In addition, low grade ores and mine wastes have occasionally been
spilled or dumped offsite.
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TABLE 2-2. STUDIES AND STATUS OF INACTIVE MILL AND ORE PROCESSING SITES
Site status
Stu'dies carried out under PL 95-60^
Site Phase I Phase II Designated "~_
Ar iz ona
Monument Valley x x x
Tuba City x x x
Colorado
Durango x x x
Grand Junction x x x
Gunnison x x x
Maybell x x x
Naturita x x x
New Rifle x x x
Old Rifle xx x
Slick Rock (NC Site) x x x
Slick Rock (UC Site) x x x
Idaho
Lowman x x x
New Mexico
Ambrosia Lake x x x
Shiprock x x x
North Dakota
Belfield - - x
Bowman - - x
Oregon
Lakeview x x x
Pennsylvania
Canonsburg - x x
South Dakota
Edgemont - -
Texas
Falls City x x x
. (d)
Ray Point x x
See footnotes at end of table.
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TABLE 2-2. STUDIES AND STATUS OF INACTIVE MILL AND ORE PROCESSING SITES
(Continued)
Mexican Hat
Monticello
Salt Lake City
Wy oining
zs
Converse County
River ton
Studies carried out
Site status
under PL 95-604
Site
Utah
Green River
„-. (e)
Phase I
x
Phase II
x
Designated
x
x
x
x
x
Totals
21
23
24
pa^Former rare-metals plant; not an inactive uranium mill site,
'b'Study done under Formerly Utilized MED/AEC Sites Remedial
Action Program.
^Owned by TVA.
^'Uranium not sold to U.S. Government.
^e ^Covered by waters of Lake Powell.
^^Owned by Department of Energy.
vg)()n U.S. Bureau of Land Management (BLM) property.
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"Evidence exists of all these mechanisms causing some degree
of increase in radioactivity above natural background. In no
other location was there evidence of the widespread use of
tailings in building construction such as occurred in Grand
Junction, Colorado. Nevertheless, there are some habitable
structures in several other locations where tailings use is
suspected.
"Measurements of dust concentrations in air made near
tailings piles in the past have not indicated significant hazard
from inhalation. However, the significance of blowing dusts
settling out in the general vicinity over a period of many years
has not been thoroughly evaluated.
"The EPA has held the position for some time that radon gas
emanating from a tailings pile may cause a detectable increase in
airborne radiation levels in the vicinity of a tailings pile,
roughly within half a mile. The gas will diffuse readily into
existing structures, but its particulate decay products would
tend to remain inside, possibly causing a buildup in
radioactivity within the structure. There is little data
available to support this hypothesis, but it needs to be checked
carefully, as it could have significant bearing on decisions
regarding removal of tailings piles from populous areas. High
radon decay product levels were found in structures close to the
Vitro pile, but the possibility of their having been built over
tailings has not been excluded.
"Water erosion does not appear to have been a significant
factor in the off site migration of tailings. However, the
movement of radium and soluble salts into the subsoil in areas
with high water table needs further evaluation. In a few
locations tailings piles are located near water courses where
flooding can be a problem.
Use of Mill Sites
"Where housing and other structures remain from the milling
operations they have been frequently put to use. Housing at Tuba
City, Naturita, Slick Rock, Shiprock and Mexican Hat is
occupied. Buildings on the mill sites at Gunnison, Naturita
Shiprock, Green River and Mexican Hat are being used for
warehousing, schools and other purposes. At several sites
buildings are still used for company activities. At Salt Lake
City a sewage disposal plant is operating on the site.
Construction of an automobile race track was begun in the middle
of the tailings pile. It was subsequently stopped by the State
upon recommendations of AEC and EPA. The pressure for use of
sites in urban areas is likely to increase with time consistent
with projected population growth. None of the areas formerly
occupied by milling facilities, ore stockpiles, etc., have been
10
-------
examined to determine the depth of soil contamination, or
suitability for future unrestricted use."
Table 2-3 contains a summary of the widely varying site conditions
at the time of the Phase I site visits (AEC74, Table I). Tables 2-4
and 2-5 contain summaries of basic Phase I findings and the con-
tractor's recommendations for potential remedies at each site,
respectively
(AEC74).
Since the Phase I studies, the Naturita pile has been moved to a
new site and reprocessed; the new site is considered active and the
tailings are not covered under Title I of PL 95-604. The Shiprock site
has been substantially cleaned up, with all buildings removed and the
pile stability improved. At some sites, buildings and other architec-
tural features, such as fences, have been changed. Finally, at all
sites further wind and water erosion of tailings has occurred.
The Phase II studies
Phase II studies (FB76-78) of 23 sites, guided by the
recommendations of the Phase I studies, began in 1975. The studies
identified site ownership and determined hydrologic, meteorologic,
topographic, demographic, and socioeconomic characteristics; alterna-
tive sites to which tailings might be moved were also identified.
Radiological surveys of air, land, and water near the tailings sites
were made, and exposures to individuals and nearby populations were
estimated. The offsite uses of tailings were identified. Finally, the
studies developed alternative remedial action plans for each site and
analyzed each plan's cost.
This Final Environmental Impact Statement incorporates many of the
results found in the Phase II reports (e.g., Chapter 3), but the
reports offer more detailed, site-specific information.
11
-------
TABLE 2-3. SUMMARY OF CONDITIONS AT TIME OF PHASE I SITE VISITS
Uranium Mill
Tailings Site
Arizona
Monument Valley
Tuba City
Colorado
Durango
Grand Junction
Gunnison
Maybell
Naturitata'
New Kitle
Old Kitle
Slick Rock (NO
Slick Rock (UC)
Idaho
Lowman
New Mexico
Ambrosia L,ake
Shiprock
Oregon
LaKeview
Pennsy Ivania
Canons burg
Texas
falls City
Kay Point
Utah
Green Kiver
Mexican Hat
Salt Lake City
Wyoming
Converse City
Condition of
Condition Buildings
of & Structures
Tailings on Millsite
U
U
PS
s
s
s
s
PS
s
s
s
U
U
PS
U
U
PS
PS
s
U
U
U
(a)pile moved to new location
(b^Not in Phase I study; study
B Building(s) intact.
E Existing.
M Mill intact.
N None.
R
PR-UO
PR-UO
PR-0
B-0
R
PR-0
M-0
PR-OU
R
R
R
PR-0
PR-0
M-OU
B-0
M-OU
M-OU
B-0
B-0
R
R
after this
performed
Mill
Housing
N
E-0
N
N
N
N
E-PO
N
N
N
E-PO
N
N
E-0
N
N
N
N
N
E-0
N
N
study.
at later
Adequate
Fencing,
Posting, &
Surveillanci
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
time.
Property
Bounded by
River or
; Stream
No
No
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
No
Yes
No
No
No
No
Yes
No
NC North Continent pile.
U Occupied or used.
Dwellings or
Industry Visual Evidence
Within 1/2 Wind or Water
Mile Erosion
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
No
No
Yes
Yes
Yes
No
P
PR
PS
R
S
U
UC
UO
No
Yes
Yes
No
No
No
Yes
Yes
No
Yes
No
No
Yes
No
Yes
Yes
No
No
Yes
Yes
Yes
No
Partially occupied.
Mill and/or buildings
Partially stabilized.
Mill and/or buildings
Possible
Groundwater Tailings
or Removed From Other
Surface Water Site for Hazards
Contamination Private Use On-Site
No
No
No
No
Yes
No
Yes
Yes
Yes
No
No
No
No
No
No
Yes
No
Yes
Yes
Yes
No
i partially removed
removed.
No
No
Yes
Yes
No
No
No
No
Yes
No
No
Yes
No
Yes
No
Unknown
No
No
No
No
Yes
No
•
No
Yes
Yes
No
No
No
No
No
No
No
No
No
No
Yes
No
No
No
No
No
No
Yes
No
Stabilized, but requires improvement.
Unstabilized.
Union Carbide pile.
Unoccupied or unused.
P Partially occupied.
-------
TABLE 2-4. SUMMARY OF PHASE I FINDINGS
Uranium Mill
Tailings Site
Arizona
Monument Valley
Tuba City
Colorado
Durango
Grand Junction
Gunnison
Maybe 11
Naturita
New Rifle
Old Rifle
Slick Rock (NC)
Slick Rock (UC)
Idaho
Lowman
New Mexico
Ambrosia Lake
Shiprock
Oregon
Lakeview
Texas
Falls City
Ray Point
Utah
Green River
Mexican Hat
Salt Lake City
Wyoming
Converse County
Totals
Years Mill
Operated
1955-67
1956-66
1943-63
1951-70
1958-62
1957-64
1939-63
1958-72
1924-58
1931-43
1957-61
1955-60
1958-63
1954-68
1958-60
1961-73
1970-73
1958-61
1957-65
1951-68
1962-65
Amount of Tailings
(Thousands of tons)
1,200
800
1,555
1,900
540
2,600
704
2,700
350
37
350
90
2,600
1,500
130
2,500
490
123
2,200
1,700
187
25,256
Total Amount
of Radium in
Tailings
(curies)
50
670
1,200
1,350
200
640
490
2,130
320
30
70
10
1,520
950
50
1,020
230
20
1,560
1,380
60
13,950
NC North Continent pile.
UC Union Carbide pile.
13
-------
TABLE 2-5. RECOMMENDATION FROM PHASE I ON PRINCIPAL ACTIONS TO BE STUDIED IN PHASE II
Uranium Mill
Tailings Site
Remove
Tailings
(I)
Stabilize
Tailings
(II)
Decontami-
nate Site
(III)
Improve
Fencing
and
Posting
(IV)
Remedial
Actions
for Build-
ings
(V)
Ground-
water
Surveys
(VI)
No
Further
Studies
(VII)
Arizona
Monument Valley
Tuba City
Colorado
Durango
Grand Junction
Gunnison
Maybe 11
Naturita
New Rifle
Old Rifle
Slick Rock (NC)
Slick Rock (UC)
Idaho
bowman
New Mexico
Ambrosia Lake
Shiprock
Oregon
Lakeview
Texas
Falls City
Ray Point
Utah
Green River
Mexican Hat
Salt Lake City
Wyoming
Converse County
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
(a)
X
X
X
X
X
X
X
(a)
(a)
X
X
(fl'Though not recorded in Phase I study, the use of tailings in building construction has since'
been reported.
Notes:
I - Remove tailings and other radioactive materials from the site to a more suitable location.
II - Stabilize tailings, complete, or improve stabilization to prevent wind and water erosion.
Ill - Decontaminate millsite or immediate area around tailings pile.
IV - Complete or improve fencing and posting of millsites and tailings areas.
V - Determine levels of radioactivity in structures where tailings may have been used in
construction, and determine costs and measures needed for remedial action where warranted.
VI - Conduct groundwater surveys in immediate area of millsite and tailings.
VII - No phase II study proposed at this time.
NC North Continent pile.
UC Union Carbide pile.
14
-------
Chapter 3: RADIOACTIVITY AND TOXIC MATERIALS IN TAILINGS
In this chapter we discuss the amounts and concentrations of
radioactivity and toxic materials found in tailings piles and released
to .nearby air and water. We also estimate the extent to which tailings
have been moved off the piles by man and by natural forces. Finally,
we discuss the levels of radioactivity in buildings due to use of
tailings, and, for the purpose of comparison, due to natural causes.
3.1 Radioactivity in Tailings
From 1948 through 1978 nearly 160 million tons of ore were
processed at uranium mills (DOE79a) to recover some 328,000 tons of
11303, a uranium-rich compound called "yellowcake." This operation
produced about 160 million tons of tailings. The 24 designated sites
contain about one-sixth of these tailings, roughly 25 million tons,
deposited in piles covering a total of about 1,000 acres. Virtually
all of the remaining tailings are at active mill sites licensed by the
NRC or by States having agreements with NRC.
Most of the uranium recovered from ore is uranium-238, a
radioactive isotope that decays, over billions of years, to become
lead-206, a stable (i.e., nonradioactive) element. The lengthy decay
process includes a number of intermediate stages (called decay
products). These, too, are radioactive. Figure 3-1 traces the steps
in this decay process. Since the ore was formed millions of years ago,
uranium has continued to decay and an inventory of all of these decay
products has built up. There are also radioactive materials from two
other decay processes in uranium ore, the uranium-235 series and the
thorium-232 series, but these are present in much smaller amounts, and
we have concluded that it is not necessary to include them in our
analysis (see Section 4.1).
When ore is processed most of the uranium is removed and most of
the subsequent decay products become part of the tailings. As a
result, thorium-230 is the radionuclide with the longest half-life of
significance in tailings. Thorium decays to produce radium-226.
Radium decays in turn to produce radon-222, a radioactive gas. Because
radon gas is chemically inert, some of it escapes from the tailings
particles in which it is produced, diffuses to the pile surface, and is
15
-------
Uranium-238
4.5 billion
years
alpha
Uranium-234
240,000
years
Protactinium
234
1.2 minutes
, beta,
gamma
Thorium-234
24 days
alpha,
gamma
(ELEMENT)
(HALF-LIFE)
(PARTICLE OR
RAY EMITTED
Thorium-230
77,000
years
Polonium-214
.00016 seconds
/ beta,
gamma
alpha,
gamma
Polonium-210
140 days
i
Bismuth-210
5.0 days
X
beta
alpha,
gamma
J
Lead-210
22 years
beta,
gamma
Lead-206
stable
FIGURE 3-1. THE URANIUM-238 DECAY SERIES.
16
-------
carried away into the atmosphere. Airborne radon produces a series of
short half-life(l) decay products that are hazardous if inhaled. If
the radon does not escape from the tailings, its decay products remain
there, and the gamma radiation they produce may increase the hazard to
people near tailings.
Since thorium has a much longer half-life than its two immediate
decay products, radium and radon, the amounts of radioactivity from
radium and radon remain the same as that from thorium. The amount of
radon released from a tailings pile remains effectively constant on a
year-to-year basis for many thousands of years, decreasing only as the
thorium, with its 77,000-year half-life, decreases.
In Figure 3-2 we show how the yearly production rate of radon in a
tailings pile will decrease with time. It falls to 10 percent of its
initial value in about 265,000 years. This time scale is typical of
and illustrates the long term nature of most of the significant
radiological hazards associated with uranium mill tailings.
100
75 -
S3
O
H O
2 P
w o
u o
K 03
W PM
PH
100
1,000 10,000
TIME (years)
100,000 1,000,000
FIGURE 3-2. RADON PRODUCTION IN A TAILINGS PILE
(1'A half-life is the time it takes for a given quantity of a
radioactive isotope to decay to half of that quantity. Figure 3-1
shows the half-lives of the members of the uranium-238 decay series.
17
-------
There are two types of chemical extraction used by uranium mills:
the acid-leach process and the alkali-leach process. The process
selected at a particular mill depends on the nature of the ore. The
radioactive and chemical characteristics of the tailings and, to a
degree, the way radionuclides are distributed within a tailings pile
depend on which process is used.
When discharged from the mill, tailings have both solid and liquid
components. The solid portion of tailings can be characterized as
either coarse sands or fine slimes. In both the acid process and the
alkali process, the residual uranium and radium content of slimes is
about twice that of sands. Usually, the total amount of thorium and
radium is the same for both processes when the pile is considered as a
whole, but differences in details of mill chemical processes sometimes
change this ratio at various places within a pile.
Radioactive materials are also discharged to tailings piles in
liquid wastes. The amount of radioactive thorium is much higher in
liquids discharged from acid-process mills than from alkaline-process
mills, because thorium dissolves readily in acidic but not in alkaline
solvents. About 5 percent or less of the radium in ore is dissolved by
either method. The chemical processing recovers only dissolved
uranium, so that essentially all of the dissolved thorium, radium, and
other radionuclides are discharged to the tailings pond (Se75).
In general, no more than about 20 percent of the radon produced by
the radium in a tailings particle leaves the particle. The remaining
80 percent (and therefore its subsequent decay products) stays locked
within the particle (Cu73). In addition, much of the radou escaping
from tailings particles decays before reaching the atmosphere and
therefore also leaves its decay products within the pile. The depth of
the tailings pile (and any cover), its porosity, and its moisture
content determine how much of the radon released from tailings
particles is ultimately released to the atmosphere. The variability of
these factors makes it difficult to predict these releases accurately.
In Table 3-1 we show, for each of the designated sites, the
quantity of tailings, area of the pile, average ore grade, estimated
average radium concentration (based on average ore grade), estimated
annual radon release and release rate from the pile, total quantity in
curies(l) of radium, maximum measured radium concentration, and some
limited information on the measured radon release rate.
"Upgrader" sites are locations from which the fine slimes have
been removed for the purpose of reworking them elsewhere to recover
residual uranium. At these sites the average radium concentration is
(1)The curie (Ci), a basic unit of radioactivity, is equal to 37 billion
nuclear transformations per second.
18
-------
probably lower than the estimated values in Table 3-1, which are based on
the average ore grade. Of the 24 sites, Green River, Monument Valley,
Slick Rock (UC), and Converse County were upgrader sites. The Naturita
mill also operated as an upgrader shortly before it was shut down.
3.2 Toxic Materials in Tailings
A number of nonradioactive toxic materials from ore or from chemicals
used in processing have been found in both liquid and solid uranium mill
wastes (Se75, FB76-78). The contaminants present depend on the ore source
and the type of processing. In Table 3-2 we indicate the average con-
centration of 15 elements found in 19 inactive tailings piles as adapted
from the work of Markos and Bush (MacSla). These data show wide variations
of element concentration among the different piles as well as wide
variations of element concentration above and below those values for
"typical soil." In Table 3-3 we give an example of more complete data that
shows how elements are divided between sands and slimes of a tailings pile
at an alkaline-leach uranium mill (Ambrosia Lake). We do not have similar
data for an acid-leach mill. The ratio of the concentration in fine
slimes, which are usually more contaminated, to that in a nearby soil
sample is included for comparison. Uranium and thorium, while radioactive,
are also potentially toxic elements and are included in this table.
3.3 Offsite Contamination Due to Natural Forces
In this section we discuss contamination of land, surface and ground-
water, and air. The land contamination is from tailings transported by
wind and water erosion; surface and groundwater contamination is from the
leaching of radionuclides and potentially toxic elements in the tailings;
and air contamination results from emissions of radon and fine tailings
particles into the air.
Land Contamination
The action of wind and water can erode tailings from unstablized piles
onto nearby land. To determine the extent of this contamination, EPA
conducted gamma radiation surveys at most of the inactive tailings sites in
the spring of 1974. Contour lines corresponding to gamma radiation levels
(above normal background) of 40 microroentgens/hr,d) 10 micro-
roentgens/hr, and zero microroentgens/hr (i.e., background) were identified
and plotted on site maps to characterize contaminated areas (Do75). In
Table 3-4 we summarize estimates of the areas within these contour lines
for the 20 inactive sites for which these surveys were carried out. In
Chapter 7 we discuss how we have used these gamma radiation levels to
estimate the extent of radium contamination in the surface soil.
' 'The roentgen (R) is a unit measuring the electrical charge gamma
radiation produces when absorbed in air (i.e., 2.58 x 10~^ C/kg). A
microroentgen is one millionth of a roentgen.
19
-------
TABLE 3-1. RADIOACTIVITY IN INACTIVE URANIUM MILL TAILINGS PILES
(e)
Location
Monument Valley,
Arizona
Tuba City,
Arizona
Uurango ,
Colorado
Grand Junction,
Colorado
Gunnison,
Colorado
Maybell,
Colorado
NaLurita,
Colorado
NJ
O
New Kifle,
Colorado
Old Rifle,
Colorado
Slick Rock (NC),
Colorado
Slick Rock (UC;,
Colorado
Lowman,
Idaho
Ambrosia Lake,
Mew Mexico
Shiprock,
New Mexico
Beltield,
North Dakota
Bowman ,
North Dakota
Amount of
Tailings Area of
(Millions Tailings
of Tons) (Acres)
1.2 30
0.8 22
1.6 21
1.9 59
0.5 39
2.6 80
0.0 (23)
2.7 32
0.4 13
0.04 19
0.35 6
0.09 5
2.6 105
1.5 72
(h)° (°7-5
(h)g (i^l2
Average / •,
Ore Grade1 '
(% u3og)
0.04
0.33
0.25
0.28
0.15
0.098
Tailings
0.31
0.36
0.28
0.25
0.19
0.23
0.25
-
-
Radium-226^ ;
Average
Concentration
(pCi/g)
50
920
700
780
420
270
pile has been
870
1,000
780
690
530
640
700
-
-
Radium-226lc;
Maximum Measured
Concentration
(pCi/g)
1,300
1,880
1,800
1,800
1,100
600
Radium-
226
(Ci)
50
670
1,200
1,350
200
640
Radon-222v '
Assumed Re-
lease Rate
(Ci/y)
200
2,600
1,900
5,900
2,100
2,800
Radon-222 Radon-222v
Estimated Release Measured Release
Rate Rate
(pCi/m s) (pCi/m s)
50
920
700
780
420
270
14-29
11-400
35-310
25-660
480
75-100
moved, only residual contamination remains 1-124
1,900
5,400
350
120
240
900
4,000
-
-
2,130
320
30
70
10
1,520
950
-
-
3,600
1,700
1,900
500
300
8,600
6,400
-
-
870
1,000
780
690
530
640
700
-
-
70-1,400
210-1,300
4-250
6-24
50-150
40-300
53-160
(g)(440-1200-2200)
1.3-63
48-94
See footnotes at end of table.
-------
TABLE 3-1. RADIOACTIVITY IN INACTIVE URANIUM MILL TAILINGS PILES (Continued)
Location
Lakeview,
Oregon
Canonsburg,
Pennsylvania
Falls City,
Texas
Green River,
Utah
Mexican Hat ,
Utah
Salt Lake City,
Utah
Converse County,
Wyoming
River ton,
Wyoming
Total
Amount of
Tailings
(Millions
of Tons)
0.13
0.4
2.5
0.12
2.2
1.7
0.19
0.9
24.42
Area of
Tailings
(Acres)
30
18
146
9
68
100
5
72
970.5
Average , , Radium-226
Ore Grade Average
(? IT n t Concentration
38 (pCi/g)
0.15 420
_ _
0.16 450
0.29 810
0.28 784
0.32 900
0.12 340
0.20 560
Radium-226
Maximum Measured
Concentration
(pCi/g)
420
4,200
160
220
1,900
2,000
650
1,100
Radium-
226
(Ci)
50
_
1,020
20
1,560
1,380
60
(m)544
13,774
Radon-222(d)
Assumed Re-
lease Rate
(Ci/y)
1,600
_
8,400
900
6,800
11,500
200
5,100
73,000
Radon- 222
Estimated Release
Rate
(pCi/m s)
420
450
810
784
900
340
560
Radon-222(e)
Measured Release
Rate
(pCi/m s)
187-710
185-296
3-78
32-128
16-1,600
(k)1_20
(1)(130- 300-650)
190-2,860
50-80
NC North Continent pile. UC Union Carbide pile.
(a)phase II Reports (FB76-78) .
(^'Calculated from average ore grade, assuming 700 pCi/g per 0.25%.
(c'Phase II Reports (FB76-78). Value shown is for highest reported soil, sediment, or tailings sample. Tailings were not sampled
in all cases .
(^'Calculated from average radium-226, assuming 1 pCi/m2s of radon-222 is released (annual average) for each pCi of radium-226
?er gram of tailings.
e)phase II Reports (FB76-78), unless indicated otherwise.
(f'Pile has been removed from site; only residual amounts remain.
(g^Bernhardt, et al. (Be75), reported values ranging from 590 to 1,320 pCi/m2s for uncovered and 440 to 2,200 pCi/m2s for
stabilized tailings.
'"'Residual contamination only.
/ • \ ,
^1'Area within site boundaries.
(J ^Bernhardt, et al. (Be75), reported values for stabilized tailings ranging from 3 to 31 pCi/m2s.
(^'Measurements by FBDU are based on a sample of tailings in a barrel, with varying moisture contents.
(1'Bernhardt, et al. (Be75), reported values for 11 sites ranging from 130 to 650 pCi/m2s, with a median of about 300 pCt/m2s.
Measurements by Bernhardt indicated overlapping ranges of radon release rates for uncovered and covered (up to several feet) tailings.
-------
TABLE 3-2. AVERAGE CONCENTRATION OF ELEMENTS FOUND IS INACTIVE URANIUM MILL TAILINGS^
to
10
( in ppm)
ELEMENT
Tailings Pile
Arizona
Monument Valley
Tuba City
Colorado
Uurango
Grand Junction
Gunnison
nay be 11
Naturita
New Rifle
Old Rifle
Slick Kock NC
Slick Kock UC
New Mexico
Ambrosia Lake
Shiprock
Utah
Green River
Mexican Hat
Vitro Uranium^)
Vitro Vanadium(c>
Wyoming
Spook
Riverton
"Typical" Soil^J
As
Arsenic
1.5
82
0.80
14
254
1.5
59
4.2
3.7
34
6.6
2.6
0.004
1.9
63
210
244
87
161
6
Ba
Barium
-
86
82
121
66
18
172
100
155
453
134
96
-
73
12
2130
3860
46
64
500
Cd
Cadmium
-
4
0.20
1.6
0.26
0.09
0.07
1.1
8.7
0.027
0.074
3.6
-
0.40
0.70
0.37
0.32
0.06
Cr
Chromium
-
6
8.8
29
5.2
9.3
3.5
55
20
4.9
3.4
8
-
17
1.0
1010
2030
26
23
100
Cu
Copper
-
1160
95
14
30
3.1
54
8
18
35
17
58
-
102
488
310
1080
14
21
20
Fe
Iron
-
7230
62
1170
20800
2100
16400
807
8250
6540
4080
90
-
1210
3650
31100
213000
15299
21800
38000
Pb
Lead
—
812
62
50
137
13
48
187
38
1250
29
—
—
121
40
3060
350
2.5
3.2
10
Hg
Mercury
—
0.001
0.87
0.026
—
0.09
—
0.001
0.25
109
0.074
0.002
—
0.001
—
—
0.03
Se
Selenium
0.064
10
1.2
3.1
1
13
0.47
1.9
2.7
0.76
2.2
68
0.18
231
6
262
391
0.2
Ag
Silver
—
6
1.2
0.72
3.8
0.15
1.1
1.4
0.46
1.7
0.57
0.15
0.070
1.0
0.022
0.066
2.2
2.4
0.1
U
Uranium
60
370
480
180
90
120
500
240
380
80
50
210
120
60
140
180
50
130
70
1.0
V
Vanadium
1850
620
3900
1760
80
120
2890
3990
520
620
1480
1590
330
1390
1350
100
830
350
240
100
Zn
Zinc
—
249
304
45
120
17
75
31
359
21
21
47
21
57
340
350
31
38
50
Ra-226(b)
Radium
(x 10~6)
50
920
700
780
420
274
—
870
1000
780
690
640
700
810
780
900
340
560
1.5
^Adapted from G. Markos and K.J. Bush, "Physico-chemical Processes in Uranium Mill Tailings and Their Relationship to Contamination" (MacSla)
vu'Table 3-1 (1 pCi/g = 1 x 10~0ppm, for Ra-226).
different parts of the Vitro Site, Salt Lake City, Utah.
-------
TABLE 3-3. ELEMENTS PRESENT IN TAILINGS SANDS AND SLIMES
FROM AN ALKALINE-LEACH MILL
-------
TABLE 3-4. ESTIMATED AREA OF CONTAMINATION AT INACTTVR MILLS(a)
Contaminated Area (Acres)
Location
Greater than Greater than
40 uR/hr above 10 uR/hr above Above
background background background
Monument
Arizona
Tuoa City
Arizona
Colorado
Grand Junction'6'
Colorado
Gunnison
Colorado
Maybe11
Colorado
Naturita^
Colorado
Rirle (New)
Colorado
Rifle (Old)
Colorado
Slick Rock (NC)
Colorado
Slick Rock (UC)
Colorado
Lowman
Idaho
Ambrosia Lake
New Mexico
Shiprock
New Mexico
(0
130
12
320
110
17
210
52
170
26
450
170
44
12
41
11
390
130
200
310
68
750
310
240
33
81
16
620
230
See footnotes at end of table.
24
-------
TABLE 3-4. ESTIMATED AREA OF CONTAMINATION AT INACTIVE MILLs(a)
(Continued)
Contaminated Area (Acres)
Greater than Greater than
40 uR/hr above 10 uR/hr above Above
Location background background background
Belfield
North Dakota
Bowman
North Dakota - - 36.
Lakeview^n'
Oregon - - -
Canonsburg^
Pennsylvania - -
Falls City
Texas 140 260 410
Green River
Utah - 44 150
Mexican Hat
Utah - 130 460
Salt Lake City
Utah 110 200 510
Converse County
Wyoming - 88 190
Riverton
Wyoming - 99 460
(NC) North Continent pile; (UC) Union Carbide pile.
^•'Reference (Do75) unless otherwise noted.
outcroppings and scattered ore made measurements difficult.
Data not available.
covered with topsoil; contaminated area not determined.
to extensive development around site, contaminated area could
not be determined.
'^Contamination from plume extends several miles down valley.
estimated to have radium in excess of 5 pCi/g (FB81).
Gamma survey not done, at request of State.
^1'Gamma survey not done.
25
-------
Little data is available about contamination of land with windblown
toxic materials. However,- it is likely that such contamination of land
exists in generally the same proportion to radioactive contamination as
it does in the tailings piles. Surface runoff may also deposit
tailings particles, and therefore toxic materials, in the vicinity of
the pile. In these cases also, the amount of radioactivity should
usually be a reasonably good indicator of the concentrations of other
elements because they, like radioactive elements, are assumed to be
relatively well fixed in tailings particles. (If they were not,
process liquids and rain water would have leached them downward into
the soil beneath the pile.)
Water Contamination
Tailings can contaminate both surface and groundwater. However,
most of this contamination appears to occur as the result of seepage of
liquid waste discharges from the mill to the tailings pile when the
mill was active. Kaufmann, et al. (Ka75), in a study conducted by EPA,
estimated that 30 percent of the process water from two active tailings
ponds in New Mexico had seeped into the ground. Purtyman, et al.
(Pu77), in a study carried out for DOE, estimated a 44 percent seepage
loss from another pile in New Mexico during its active life.
The NRC, in its Final Generic Environmental Impact Statement
(PGEIS) on Uranium Milling (NRC80), assumes that a model site will
experience a 40 percent water loss by seepage and uses mathematical
models to estimate the movement of this seepage through unsaturated
soil, formation of a seepage "bulb" in the saturated .soil zone, and the
movement of pollutants with groundwater. For its model mill in an arid
region, NRC concluded that about 95 percent of the possible
contamination of groundwater would be associated with the active phase
of the pile and only 5 percent with long-term losses from the inactive
pile (NRC80).
There is evidence that groundwater near some inactive sites is
contaminated, probably due to seepage of liquids from tailings ponds
during and soon after their active use (Dr78). Groundwater contaminant
concentrations near the inactive mills were surveyed as part of the
Phase II studies (FB76-78), and some cases of elevated concentrations
were found. Additional case histories showing some water contamination
problems near uranium mills and mines are given in a recent report
(UI80). Contamination that extends up to 8,000 feet from active
tailings piles has been found, but this is usually in shallow alluvial
aquifers (UI80). In Table 3-5 we summarize the elements found in
elevated concentrations in groundwater near tailings piles.
Contamination of deep aquifers has not been observed, but may be
possible (UI80). Markos has shown that many of the soluble elements in
piles tend to precipitate and form a barrier when liquids move downward
in the pile to the soil at the tailings-soil interface (Mac79; MacSla-
81b). This would prevent contamination of groundwater from inactive
tailings. However, how long this barrier will last is not known, and
there could be channels through the barrier at locations other than
26
-------
TABLE 3-5. ELEMENTS FOUND IN ELEVATED CONCENTRATIONS IN GROUNDWATER
NEAR TAILINGS SITES
(a)
Tailings Site
Elements
(b)
Gunnison, Colorado
Ambrosia Lake, New Mexico
Falls City, Texas
Green River, Utah
Ray Point, Texas
(c)
Grants Mineral Belt, N.M.
(Active Mills)
Arsenic, Barium, Chromium, Iron,
Lead, Selenium, Vanadium
Barium, Lead, Vanadium
Arsenic, Barium, Chromium, Iron,
Lead, Selenium, Radium, Vanadium
Arsenic, Chromium, Lead, Selenium
Arsenic
Polonium, Selenium, Radium,
Vanadium, Uranium, Ammonia,
Chloride, Nitrate, Sulfate
(FB76-78, Ka75) .
most sites there are other potential sources of toxic material
contamination; see orginal reports for details.
(c)Not designated under the Act because the uranium produced was not sold
to the U.S. Government.
those sampled. DOE is currently sponsoring additional studies of the
potential for groundwater contamination.
Markos also concludes that the deliquescent and hygroscopic
properties of the salts in piles act to scavenge moisture from the
atmosphere or shallow water tables and move water from areas of low
salt concentration to high salt concentration (Mac79). Osmotic and
capillary pressure in tailings can also cause a net movement of water
to the surface of a pile. This can lead in turn to the deposition of
radioactive and other salts on pile surfaces. In contrast, studies by
Klute and Heermann (K178) indicate that even in dry climates
precipitation can produce a downward flow of water through tailings.
Standing water with elevated concentrations of toxic materials has
been reported on and adjacent to some tailings sites (MacSlb, FB76-
78). Usually these concentrations are intermediate between those
reported for waters within piles and normal levels in surface water.
Surface water runoff from rains and floods can wash surface salt
deposits and tailings from an unprotected pile, causing spread of toxic
and radioactive elements to nearby land and streams. However, the
limited studies that have been made do not show nearby streams being
contaminated by inactive tailings piles (FB76-78).
27
-------
Future contamination of surface or groundwater by a pile is likely
if there is erosion of toxic elements from a pile by tain, by flooding,
or, possibly, by the flushing action of seasonal changes in the water
table when it can reach a pile. Severe floods have greater but
unevaluated potential for producing significant contamination in
streams and rivers. Future groundwater contamination from the seepage
and flushing action of seasonal change in the water table is uncertain.
Air Contamination
The most significant radionuclide released to air is radon. In
Table 3-1 we show both calculated and measured radon emission rates(1)
from the 24 designated sites. Most of the calculated emission rates
range from 300 pCi/m2s to 1000 pCi/m2s. Radon emission rates from
uncontaminated soils are much lower, averaging close to 1 pCi/m2s,
with a range of perhaps as much as a factor of 2 or 3 higher and lower.
To estimate the annual radon release rates reported in Table 3-1 we
assumed that the radon emission rate per unit area is 1.0 pCi/m2s per
pCi/g radium; this value was also used by NRC (NRC80, Appendix G). We
have also assumed that the piles are dry, homogeneous, not covered, and
at least 3 meters deep. By way of comparison, Haywood (Ha77) has
calculated values of 0.35, 0.65, and 1.2 pCi/m2s radon per pCi/g
radium for wet, moist, and dry tailings, respectively.
The measured radon release rates listed in Table 3-1 are generally
less than we have estimated using the average radium concentration in
tailings and assuming dry piles. In reality, of course, many tailings
piles still contain significant residual moisture. Several have also
been subjected to temporary stabilization measures, which should also
reduce the release of radon. However, we consider it reasonable to
assume that, over the term of interest for the hazards associated with
release of radon (hundreds of thousands of years), the piles would be
dry most of the time and that any existing temporary stabilization
would not persist for such time spans.
Tailings piles also release fine tailings particles to the air.
Schwendiman et al., have studied particle release rates from an active
pile (ScbSO). Their data show that for wind speeds from 7 mph to
25 mph, the airborne mass loading downwind from the pile is roughly
5 x 10~4 g/m3. This is an order of magnitude greater than the mass
loading measured just upwind from the site. The airborne
concentrations of several radioactive and toxic elements were also
measured, showing that the windblown particles from a tailings pile
contain a variety of radionuclides, as well as selenium, lead, arsenic,
mercury, and molybdenum. However, the air concentrations observed were
(1)The term emission rate is used rather than fluence rate or flux
density, which although more precise are generally less familiar.
28
-------
well below the 8-hour threshold limit values to which workers can be
repeatedly exposed without adverse effect. (These values for
occupationally exposed workers were established by the American
Conference of Governmental Industrial Hygienists (AC81).)
Potential for Massive Tailings Dispersal by Floods
Most of the 24 designated sites are in locations that are not
vulnerable to severe flooding or water erosion and the massive
dispersal of tailings that would accompany such events. However, some
sites are, in varying degrees, subject to these hazards because of
their nearness to streams or because they are located in the flood
plains of rivers. The following is a brief descriptive listing of
conditions at piles that may be subject to such hazards (FB81):
Durango: The tailings are piled in a steep, unstable
slope above the Animas river. Large slides
into the river are possible.
Grand Junction, The piles are vulnerable to the 100-year flood
Slick Rock (UC), of a major watercourse (the Colorado and
Slick Rock (NC): Dolores rivers).
Canonsburg, The piles are vulnerable to the 100-year flood
Salt Lake City: of a minor watercourse (Chartiers and Mill
creeks).
New Rifle, The piles are vulnerable to the 500-year flood
Old Rifle: of a major watercourse (the Colorado River).
Lowman: The pile is on a mountainside terrace. Some
areas of this small pile, if it remains in its
present configuration, could experience severe
erosion in heavy rainstorms. These are
projected to occur at a frequency of one in ten
years.
3.4 Offsite Contamination Caused by Man
In 1972, using a detector mounted on a van, EPA and AEC personnel
surveyed towns near tailings piles and located a large number of gamma
radiation amomalies—locations exhibiting higher-than-normal gamma
radiation levels.
As a followup, teams from EPA and State health departments
conducted further studies to determine the sources of these anomalies
(EPA73). The results are summarized by State and town in Table 3-6.
The sources were categorized in these studies as (1) uranium mill
tailings, (2) uranium ore or manmade sources, (3) naturally occurring
radioactivity not due to uranium tailings or ore, and (4) unknown. At
over 6,500 locations (roughly 5,000 in Grand Junction, Colorado,
29
-------
TABLE 3-6. LOCATION AND NUMBER OF GAMMA RADIATION ANOMALIES—-1972 SURVEY
(a)
Location
Arizona
Cane Valley^)
Cameron
Cutter
Tuba City
Subtotal
Colorado
Cameo
Canon City
Clifton
Collbran
Craig
Debeque
Delta
Dove Creek
Durango
Fruita
Gateway
Glade Park
Grand Junction^0'
Grand Valley
Gunnison
Leadville
Loma
Mack
Mesa
Mesa Lakes
Molina
Naturita
Nucla
Palisade
Plateau City
Rifle
Saliaa
Slick Rock
Uravan
Whitewater
Subtotal
Idaho
Idaho City
Lowman
Salmon
Subtotal
New Mexico
Bluewater
Gamer co
Grants
Milan
Shiprock
Uranium
Tailings
15
-
-
7
"22
1
36
159
4
8
2
1
59
118
58
12
1
5178
10
3
18
10
6
•1
-
-
10
3
107
1
168
6
3
208
—
6191
-
9
1
"To
i
-
7
5
8
Number and Type
Uranium Ore or
Manmade Source
4
1
5
-
To
-
-
24
34
2
7
-
3
19
67
48
2
_
(d)7229
2
9
2
4
2
2
-
-
20
6
39
-
27
2
6
-
4
(d)(7560)
-
-
2
~2
1
-
50
27
1
of Anomaly
Other Natural
Radioactivity
-
-
-
3
3
-•
99
14
-
46
1
29
2
67
26
-
_
(d)
-
28
65
4
-
-
-
-
1
2
14
-
1
52
-
-
2
453
2
3
65
To
-
5
25
1
-
Unknown
-
2
-
7
"9
2
28
876
139
25
106
10
3
102
1144
3
2135
98
7
6
181
82
120
3
43
2
2
779
27
614
4
-
1
49
(6591)
1
-
9
To
-
-
19
8
-
Total
Anomalies
19
3
5
17
44
3
187
1083
145
86
109
43
83
354
1276
17
1
14542
110
47
91
199
90
123
3
43
33
13
939
28
810
64
9
209
55
20,795
3
12
77
"92
2
5
101
41
9
Subtotal
21
79
31
27
158
See footnotes at end of table.
30
-------
TABLE 3-6. LOCATION AND NUMBER OF GAMMA RADIATION ANOMALIES—1972 SURVEY
(a)
Location
Oregon
Lakeview
New Pine Creek
Subtotal
South Dakota
Edgemont
Edgemont and
Dudley^
Hot Springs
Provo
Subtotal
Texas
Campbellton
Coughran
Falls City
Fashing
Floresville
George West
Karnes City
Kenedy
Panna Maria
Pawnee
Pleasanton
Poth
Three Rivers
Tilden
Whitsett
Subtotal
Utah
B landing
Bluff
Cisco
Crescent Junction
Green River
Magna
Mexican hat
Mexican Hat
(Old Mill)
Moab
Monticello
Salt Lake City(f)
Thompson
Subtotal
Washington
Creston
Ford
Reardan
Springdale
Subtotal
Uranium
Tailings
-
-
^^~
43
17
-
3
~63
-
-
2
-
-
-
2
1
-
-
-
-
1
-
-
~6
10
-
-
-
1
1
-
10
15
31
70
26
164
-
-
-
-
~
(Continued)
Number and Type
Uranium Ore or
Manmade Source
2
1
I
3
16
3
1
"23
1
-
-
1
-
-
-
1
-
1
3
-
-
-
-
T~
21
1
2
1
14
2
5
3
83
19
15
3
169
-
-
-
—
~
of Anomaly
Other Natural
Radioactivity
10
-
To
i
51
17
-
"69
6
1
3
-
14
10
6
13
3
-
17
14
2
11
1
Tol
3
-
-
-
1
21
-
1
6
-
76
~
108
3
1
10
2
16
Unknown
6
3
~9
8
_
25
—
"33
-
-
-
-
2
-
2
7
-
-
1
1
2
_
-
Is
4
1
-
1
7
3
-
-
21
9
64
1
111
-
-
-
-
~
Total
Anomalies
18
4
"22
55
84
45
4
188
7
1
5
1
16
10
10
22
3
1
21
15
5
11
1
129
38
2
2
2
23
27
5
14
125
59
225
30
552
3
1
10
2
"16
See footnotes at end of table.
31
-------
TABLE 3-6. LOCATION AND NUMBER OF GAMMA RADIATION ANOMALIES—1972 SURVEY
~(Continued)
(a)
Location
Wyoming
Hudson
Jeftery City
Lander
Kiverton
Shirley Basin
Subtotal
GRAND TOTAL
Uranium
Tailings
-
13
4
15
9
41
6518
Number and Type
Uranium Ore or
Manmade Source
2
10
9
15
—
36
(d)7889
of Anomaly
Other Natural
Radioactivity
5
3
53
33
~
94
(d)955
Unknown
1
2
20
23
~
46
6851
Total
Anomalies
8
28
86
86
9
217
22,213
EPA report ORP/LV-75-2, August 1975. Cane Valley was not included in
the initial gamma survey program.
remedial action program for buildings with tailings has been in progress
since 1972 under Public Law 92-314.
data for Grand Junction, Colo, does not distinguish the category
"Radioactive source or ore" from "Natural radioactivity."
of additional anomalies conducted in 1978.
Lake City was not completely surveyed.
32
-------
alone), the presence of tailings was identified. The fourth category
(unknown sources) may include some locations where tailings were the
cause of the anomaly but could not be positively identified as such.
In later studies at Grand Junction, Colorado, tailings were found
at about 6,000 locations (DOE79b). This number is comparable with the
1972 gamma survey of mill tailings communities and suggests that the
1972 survey provides a fairly reliable census of the offsite use of
tailings from the designated sites.
Tailings at these anomalies were used in miscellaneous ways on
offsite properties and in building construction. Common uses of
tailings were in sidewalks, driveways, fence footings, and in gardens.
Generally, most of the tailings were used with relatively little
dilution, so one would expect that radium concentrations at these
locations are usually in excess of a few tens of picocuries per gram.
Tailings used in building construction were commonly used as fill
around the foundations and under concrete slabs.
Contaminated properties
We expect the number of contaminated offsite properties, exclusive
of uses in buildings construction, to be about equal to the total
number of anomalies due to misuse of tailings. When tailings were used
in building construction they were usually used eleswhere on the
property. The 1972 survey would count both as a single anomaly.
Therefore, we estimate there are about 6,500 contaminated
properties, of which about 5,200 are in Grand Junction alone. We do
not have detailed information of the amounts of tailings on these
properties. However, inspection of a sample of the survey records for
Grand Junction reveals, for uses not associated with habitable
ouildings, the following distribution of tailings locations:
Location Percent of Locations
City walks 22
Yards, lawns 16
Driveways, carports 14
Flower beds, gardens 14
Private walks 12
Patios 9
Detached buildings 6
Fences and posts 4
Other 3
Contaminated Buildings
Tailings have been used in the construction of a large number of
buildings, principally in Grand Junction, Colorado. This practice has
often resulted in significant levels of radioactive contamination, most
33
-------
commonly observed as elevated levels of radon decay products in indoor
air. To correct this, a remedial program has been underway in Grand
Junction for several years (under PL 92-314). Most of our assessments of
the impact of tailings used in other communities and of the costs for
their removal are based upon the experience to date in Grand Junction. In
Grand Junction, tailings were used primarily as fill around structures, in
footings, and under basement slabs. In a few cases tailings were
incorporated into concrete or mortar. A preliminary analysis of the
extensive surveys conducted by EPA in 1972 indicates that tailings were
used in other communities in the same ways as in Grand Junction.
Although it is impossible to determine the exact number of buildings
in other communities that have been contaminated by tailings, the 1972 EPA
survey provides some basis for an estimate. In Grand Junction, the 1972
survey recorded 5178 anomalies attributed to the use of tailings. If
anomalies of unknown origin are added, the total is 7313. From subsequent
detailed monitoring in Grand Junction, it is estimated that 740 structures
will require remedial action based on a criterion of 0.017 Working
Levels.tD This is roughly one-seventh of the number of
tailings-related anomalies and one-tenth of the total anomalies.
The 1972 survey identified 1340 anomalies caused by tailings in all
other communities combined. If the same one-seventh ratio applies, then
about 200 buildings are contaminated. The total in other communities for
tailings plus unknown anomalies is 6056; if the one-tenth ratio applies to
this much higher value, then about 600 buildings are contaminated. On
this basis, we guess that the number of contaminated buildings in
communities other than Grand Junction lies between 200 and 600.
To estimate the distribution of radon decay product levels in
buildings we also relied on the Grand Junction experience. Of the 740
buildings identified as requiring remedial work in Grand Junction, we have
detailed measurements on 190 carefully monitored residential buildings on
which remedial work has already been carried out. In these buildings the
mean indoor radon decay product concentration before remedial work was
0.08 WL. The distribution of these measured levels is shown in Figure
3-3. We have assumed that the distribution of levels in contaminated
buildings in other communities will be similar.
(^Working Level (WL) is a measure of exposure to radon decay products.
It is defined as any combination of short half-life radon-222 decay
products in 1 liter of air that will result in the ultimate emission of
alpha particles with a total energy of 130 billion electron volts. It was
developed to measure exposure to workers in uranium mines. The Grand
Junction survey is using as a screening criterion for starting remedial
action the radon decay product level of 0. 01 WL above background where the
background is assumed to be 0.007 WL.
34
-------
s
PQ
Pn
O
w
w
CM
35 r
30
25
20
15
10
0.017
I
I
I
1
I
I
0.02 0.04 0.06 0.1 0.2 0.4 0.6 1.0 1.4
RADON DECAY PRODUCT LEVELS (WL)
FIGURE 3-3. DISTRIBUTION OF RADON DECAY PRODUCT LEVELS IN 190
CONTAMINATED RESIDENTIAL BUILDINGS IN GRAND JUNCTION, COLORADO(Laa79)*
*Only homes with measured levels greater than 0.017 WL are included.
35
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The indoor gamma radiation level in these contaminated buildings in
Grand Junction was also measured. Roughly 65 percent had a gamma
radiation level more than 10 microroentgens/hr above background, 35
percent more than 20 microroentgens/hr above background, and about 10
percent more than 40 microroentgens/hr above background. Of all the
buildings in Grand Junction in excess of 20 microroentgens/hr above
background, about 94 percent also had radon decay product levels exceeding
0.017 WL (or 0.01 WL above background)(DOE80).
3.5 Indoor Radon Decay Product Concentrations Due to Natural Causes
Virtually all indoor atmospheres contain some measurable radon decay
products. The radon decay product concentration in a building affected by
tailings is the sum of the contributions from tailings and the natural
environment. The separate contribution from each cannot be distinguished
by measurement of air concentration. In order to judge the degree of
contamination of buildings, therefore, knowledge of radon decay product
concentrations in buildings unaffected by tailings is needed.
The most complete studies of normal indoor radon decay product
concentrations in the United States have been performed on residences in
Grand Junction, Colorado (Peb77); New Jersey and New York (Ge78); and
Florida (FD78). The New Jersey-New York buildings were mostly
single-family one- or two-story buildings. The Grand Junction buildings
were mainly houses identified as free of tailings, about half of which had
basements, and the data are for the lowest "habitable portion" of the
building (Laa79). The Florida buildings were mainly single-family houses,
without basements, in areas free of phosphate minerals. A more recent
study in a Montana mining community provides a good example of anomalously
high indoor decay product levels comparable to those found due to tailings
in Grand Junction (RPC80). This is not a useful example of normal indoor
levels, however, because of the unique circumstances involved.
Selected results from these studies are summarized in Table 3-7. In
all cases, the reported concentrations are the average of several
measurements taken over a 1-year period. The data for most locations
exhibit a range of about a factor of 10 in normal indoor radon decay
product concentrations. The New Jersey-New York data show that
concentrations in rooms at ground level are generally about half of those
in basements. An unpublished analysis of the Grand Junction data shows a
similar effect (Laa79).
In summary, the above studies indicate that:
1. Indoor radon decay product concentrations normally vary
over about a factor of 10.
2. Indoor radon decay product concentrations greater than
0.01 WL in a usable part*of a building are common.
3. Excluding basements, normal concentrations greater than
0.02 WL are rare, except in localities with unusually
large sources of radon.
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TABLE 3-7. INDOOR CONCENTRATIONS OF RADON DECAY PRODUCTS
IN AREAS FREE OF TAILINGS ) References (Pe77) and (La79) , values from lowest habitable locations.
(°) Reference (Ge78) .
WReference (F178); this sample excludes houses on phosphate lands,
which generally show elevated levels of indoor radon.
(e)unpublished EPA data, completed May 1981.
Reference (RPC80).
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Chapter 4: RISKS TO HEALTH FROM URANIUM TAILINGS
In this Chapter, after an introductory general discussion and a
characterization of radon exposure, we examine the major pathways by
which radioactive and toxic materials from tailings can reach man. We
then review the risks to man exposed to these materials. Finally,
using this information, we estimate potential effects of tailings on
the health of local, regional, and national populations.
4.1 Introduction
Among metallic ore wastes, uranium tailings piles are unusual
because of the amount of radioactivity they contain. Radioactivity
constitutes the principal source of hazard to health of these wastes,
although nonradioactive toxic chemicals such as arsenic, lead,
selenium, mercury, sulphates, and nitrates are usually present.
Milling of uranium ore removes about 90 percent of the uranium in the
ore. The remainder, along with most other radioactive materials and
toxic chemicals, is discarded in the liquid and solid wastes discharged
to tailings piles.
The principal isotope of uranium, uranium-238, decays over
billions of years to become lead, a stable nonradioactive element.
This lengthy decay process involves a series of intermediate
radioactive decay products, such as thorium-230, radium-226, and
radon-222. Figure 3-1 traces the steps in this decay process. The
decay of uranium since the ore was formed millions of years ago has
built up an inventory of these decay products, which are present in
uranium mill tailings in various concentrations.
The dominant hazard from tailings is due to the radioactive decay
products of uranium-238, particularly radium-226 and its short
half-life decay products. Each gram of natural uranium ore contains
about 500 pCi of uranium-238. In addition, natural uranium ore
contains about 23 pCi of uranium-235 and 2 pCi of thorium-232. Because
they occur in relatively small proportions and/or pose much less risk
to health, uranium-235 and thorium-232 and their radioactive decay
39
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products may usually be ignored in evaluating the hazard of uranium
tailings. '•*•'
Uranium tailings emit three kinds of radiation: alpha particles,
beta particles, and gamma rays. All are forms of ionizing radiation,
which breaks up molecules into electrically charged fragments called
ions. In biological tissues, this ionization can produce harmful
cellular changes. At the low radiation levels usually encountered in
the environment we expect the effects of such changes to be difficult
to detect. Studies show, however, that people exposed to radiation
have a greater chance of developing cancer. If the ovaries or testes
are exposed, the health or development of future children may also be
damaged.
One cannot predict with precision the increased chance of cancer
or genetic damage after exposure to radiation. We have based our risk
estimates on studies of persons exposed at doses higher than those
usually resulting from tailings and the assumption that at lower doses
the effects will be proportionally less. This assumption may
overestimate or underestimate the actual risk, but it is the best that
can be done at present (EEA76a) .
Alpha, beta, and gamma radiations from mill tailings can all cause
cancer or genetic damage. However, the major threat comes from
breathing air containing radon decay products with short half-lives—
polonium-218, for example—and exposing the lungs and other internal
organs to the alpha radiation these decay products emit. In addition,
people may be directly exposed to gamma rays from radioactive material
in the tailings pile, and radioactive tailings particles may be
transported into the body by breathing or ingestion.
The body's internal organs would still be exposed to radiation
from radionuclides even if uranium tailings piles suddenly disappeared,
because radon, radium, uranium, thorium, and other radioactive elements
occur naturally in the air, rock, and soil. One picocurie of radium
per gram of soil is a typical concentration; outdoor air contains a few
tenths of a picocurie of radon per liter (UN77). Normal eating and
breathing introduces these and other radioactive materials into the
body, increasing the potential for cancer and genetic changes. This
discussion, therefore, also compares the health risks from tailings to
those from normal exposure—not to justify the tailings risk, but to
provide a realistic context for comparison.
Tailings also contain toxic elements that could eventually be
inhaled or ingested by man and animals or absorbed by plants. Windblown
d)u-235 decay products are usually present in tailings at much lower
levels than U-238 decay products. However, at one inactive site
(Canonsburg, Pa.), U-235 decay products may be present in elevated
concentrations (C179).
40
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tailings inhaled by man or animals are unlikely to cause any toxicity
problems because the mass of inhaled material is so small. However,
the toxic elements in windblown tailings could be absorbed by plants
growing near a pile and could be a potential pathway leading to chronic
toxicity diseases in men or animals eating those plants. Moreover,
toxic elements from tailings could leach or seep into water supplies
used for irrigation or drinking. Finally, windblown tailings and radon
decay products could be deposited directly onto some foods, such as
lettuce and spinach.
It is important to distinguish between acute and chronic
toxicity. Acute toxicity (or poisoning) occurs when enough of the
toxic element is consumed to interfere with a vital body or organ
function. The severity of the poisoning is usually proportional to the
amount of the toxic element consumed, and in extreme cases death or
permanent injury will occur. Chronic toxicity is more insidious. It
occurs when small amounts of a toxic element are consumed over a
prolonged period of time. A small fraction of each intake may be
deposited in tissues or organs. Toxic symptoms appear when the
cumulative deposit exceeds a critical level. Alternatively, each
intake of a toxic element may cause a small increment of organ damage.
Symptoms of toxicity become apparent when this damage accumulates to a
critical extent. Symptoms of chronic toxicity may be reversible if
consumption of the toxic element is stopped, or they may be
irreversible, progressive, or both.
In the case of tailings, acute toxicity would be a problem only if
standing water adjacent to or on a pile is consumed. Chronic toxicity
is more likely and is therefore examined in later discussions.
4.2 Radon and Its Immediate Decay Products
Since the milling and extraction processes have removed most of
the uranium from the ore, the longevity of the remaining radioactive
members of the uranium series is determined by the presence of
thorium-230, which has an 80,000-year half-life. The thorium-230 decay
product, radium-226, has a 1600-year half-life. Both thorium and
radium are relatively insoluble and immobile in their usual chemical
forms. However, the decay product of radium-226 is radon-222, an inert
radioactive gas, that readily diffuses through interstitial spaces to
the surface of the tailings pile where it becomes airborne. The
half-life of radon-222 is 3.8 days, so some radon atoms can travel
thousands of miles through the atmosphere before they decay.
As shown in Figure 3-1, the radon decay process involves seven
principal decay products before ending with nonradioactive lead. The
four short half-life radioactive decay products immediately following
radon are the most important source of cancer risk. These decay, for
the most part, within less than an hour. Members of the decay chain
with relatively long half-lives (beginning with lead-210, which has a
41
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22-year half-life) are more likely to be ingested than breathed and
represent much smaller risks.
The principal short half-life products of radon are polonium-218,
lead-214, bismuth-214, and polonium-214. Polonium-218, the first decay
product, has a half-life of just over 3 minutes. This is long enough
for most of the electrically charged polonium atoms to attach
themselves to microscopic airborne dust particles that are typically
less than a millionth of a meter across. When breathed, these small
particles have a good chance of sticking to the moist epithelial lining
of the bronchial tubes in the lung.
Most of the inhaled particles are eventually cleared from the
bronchi by mucus, but not quickly enough to keep the bronchial
epithelium from being exposed to alpha radiation from polonium-218 and
polonium-214. This highly ionizing radiation passes through and
delivers radiation doses to several types of lung cells. The exact
doses delivered to cells that eventually become cancerous cannot be
characterized adequately. Also, we do not have detailed knowledge of
the deposition pattern of the radioactive particles in the lung and the
distances from them to cells that are susceptible. Further, there is
some disagreement about the types of bronchial cells where cancer
originates. Therefore, we have based our estimates of lung cancer risk
on the amount of inhaled radon decay products to which people are
exposed, rather than on the dose absorbed by the lung.
The exposure to radon decay products is expressed in terms of a
specialized unit called the Working Level (WL). A Working Level is any
combination of short half-life radon decay products that emits 130,000
million electron volts of alpha-particle energy in 1 liter of air. The
unit of cumulative exposure to radon decay products is the Working
Level Month (WLM), which is exposure to air containing 1 WL of radon
decay products for a working month, which is defined as 170 hours.
(These units were developed to measure radiation exposure of workers in
uranium mines.) Continuous exposure of a member of the general
population to 1 WL for 1 year is equivalent to about 27 WLM. For
exposures occurring indoors, we assume a 75 percent occupancy factor.
Thus, an indoor (residential) exposure to 1 WL for 1 year is equivalent
to about 20 WLM (EBA79a-b) .
4.3 Exposure Pathways
Tailings, depending on how they are managed or misused, may lead
to radiation exposure of man in a number of ways. Tailings removed
from piles and used for landfill, for improving drainage around
foundations, or for other construction purposes typically pose the
largest hazard by increasing indoor concentrations of radon decay
products. Tailings at a disposal site emit radon gas into the
atmosphere and are a source of radioactive windblown particulates and
direct gamma radiation. They may* also be a source of toxic chemicals
through erosion and leaching.
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4.3.1 Indoor Exposure Due to Misuse of Tailings
The greatest hazard from tailings removed from piles and used in
construction is their potential to increase levels of radon decay
products in buildings. The concentration of radon decay products in a
building will depend mainly on the amount of radium in the tailings
that are in, under, or adjacent to it. However, so many other factors
affect the indoor concentration that establishing a useful correlation
with the amount of radium is difficult.
Healy and Rogers (He78) have anaylzed exposure pathways due to
radium in soils, whether it occurs naturally or as contamination. They
argue that one might expect indoor radon decay product concentrations
of 0.01 WL for soils with radium concentrations of 1 to 3 pCi/g to a
depth of 1 meter or more. NRC estimates (NRC79) that it takes 3 to 5
pCi/g of radium to cause indoor concentrations of 0.01 WL. Radium
concentrations near the lower end of these ranges, 1 pCi/g, correspond
to common soils. The indoor concen- trations reported in Chapter 3
are, in general, consistent with the NRC estimates.
4.3.2 Exposure to Radon Decay Products from Tailings Piles
We have estimated radon decay product exposures to local,
regional, and national populations. Because of radon's 3.8-day
half-life, worldwide impact is not significantly greater than the sum
of impacts on these three groups. Details of the local and regional
dispersion calculations and population estimates have been published by
EEA (Sw81) .
In the immediate vicinity of a tailings pile, measurements can
distinguish enhanced levels of radon due to the pile from the ambient
concentration due to other radon sources. We have used these
experimental measurements to estimate the risks to the individuals
living near six urban piles. Radon from the inactive piles makes only
a small increment in the total radon exposure of the U.S. population.
Nevertheless, inactive tailings piles increase ambient levels of radon,
and we have not disregarded this even though the increase is not
directly measurable.
Windblown tailings on nearby land supplement the pile as a source
of radon. It has been estimated that radon emissions from a pile site
may be increased as much as 20 percent if the emanation from windblown
tailings is taken into account (ScbSO).
For purposes of estimating impacts, we have assumed a theoretical
pile that has a uniform radium concentration of 500 pCi/g, is
completely dry, and has not been stabilized (e.g., covered with clean
earth). For these conditions, we assume an emission rate of 1.0
pCi/m s radon per pCi/g of radium. We further assume that the pile
43
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covers an area of 31 acres and is infinitely deep.(D The resulting
radon release rate for this pile is 2000 Ci/y.
We have estimated the impact of radon releases for specific piles
by scaling results calculated for the theoretical pile (Sw 81)
according to the annual radon release of the pile. Referring to
Table 3-1, we see the estimated radon release rates range from 200 to
11,500 Ci/y. Corrections were not made for pile area sizes different
from the theoretical pile. Such corrections for persons at distances
greater than twice the pile radius from the pile center would be less
than 10 percent. These corrections are small compared to those that
could result if site specific meterology dispersion data were used
instead of the Fort St. Vrain dispersion data averaged over all
directions (see below).
Radon Dispersion
The atmospheric dispersion of radon from the above theoretical
pile at distances up to 7.5 miles was calculated using a
sector-averaged gaussian plume model (Gia68) and wind frequency data
(directon, speed, and stability) for the Fort St. Vrain reactor site in
Colorado (Sw81). Dispersion factors were averaged over all directions
to estimate a single value for each distance; i.e., dispersion was
assumed to be the same in all directions. The average windspeed for
the site was 6.5 mph.
We used this generic approach because adequately detailed
meteorological data for site-specific dispersion estimates are not
available. Clearly, such site-specific estimates would show
differences with both distance and direction. However, the generic
approach should provide reasonable estimates of the average exposure of
individuals living near a pile. We do not expect a high degree of
accuracy for any specific individual's location, since wind direction
patterns can be highly asymmetric.
Regional (7.5 miles to 50 miles) dispersion estimates for radon
from the pile were based on a model developed by the National Oceanic
and Atmospheric Administration (NOAA) (Maa73). Again, local
meteorology was not considered for these estimates, and dispersion was
averaged over all directions.
Recently, NOAA has developed a model for the Nuclear Regulatory
Commission (NRC79) to calculate the concentration in air across the
continent due to radon emitted from four sites in the West. National
(l)fiy infinitely deep, we mean that we do not reduce our radon
release estimates to correct for the finite depth of a pile. A pile
10 feet deep has a radon emission rate only about 4 percent less than
an infinitely deep pile.
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collective exposures from these four sites range from 0.42 to 0.76
person-WL per 1000 Ci released per year. We have used the average of
these estimates, 0.56, to make estimates of the total exposure of the
United States population.
In addition to these offsite calculations, we have also estimated
radon concentrations over and close to the edge of a generic covered
tailings pile, which, for calculational convenience, we take as
circular in shape. For these calculations we assumed that the cover
reduces the radon emission rate to a uniform 20 pCi/m^s over the
covered tailings. Concentrations for other emission rates would be
proportionately higher or lower. The concentration calculations were
made using generic wind data from the NRC GEIS (NRC80) and the
A1RDOS-EPA dispersion model (EPA79c). The resulting average
concentrations are shown in Figure 4-1 for a small (5 ha or 12 acres),
a medium (20 ha or 49 acres), and a large (80 ha or 196 acres) tailings
pile. Our calculations show that the average concentration near the
center of the pile and at the edge of the pile are relatively
insensitive to the size of the pile. For the 20-hectare pile, Figure
4-1 also shows the results in the directions for which the
concentration is maximum or minimum. The wind data (and therefore the
dispersion) and the shape of the pile at actual sites would differ
i.o
o
a
.5
o
o
o
o
o
0.1
I I I
I I I I I I
50 100 500
DISTANCE FROM CENTER OF PILE (m)
1000
FIGURE 4-1. RADON CONCENTRATION VERSUS DISTANCE FROM TAILINGS
PILE CENTER. RADON EMISSION RATE IS 20 pCi/m2s
45
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from the one used for these calculations, in particular, lower wind
velocity and greater directional asymmetry would tend to increase the
maximum concentration at the edge of the tailings somewhat above the
value of 0.3 pCi/1 shown in Figure 4-1 for a 20-ha pile. We have not
performed site-specific calculations, however.
Ingrowth of Radon Decay Products
At the point radon diffuses out of the ground the concentration of
associated decay products is zero because these decay products have
been captured in earth. As soon as radon is airborne decay product
ingrowth continues and an equilibrium between the amount of radon and
the amount of each decay product is approached. At equilibrium there
is equal activity of all the short half-life radon decay products in
air, and alpha radiation is maximized. We use a concept called the
equilibrium fraction, which is the fraction of the potential alpha
energy from decay products at complete equilibrium to that actually
present. Since the radon and its decay products are transported by the
wind, the equilibrium fraction increases with distance from the pile as
the decay products grow in.
Evans (Ev69) has calculated decay product ingrowth with time for a
constant radon concentration. Since the half-life of radon is much
greater than that of its short-lived decay products, these values can
be used to calculate approximately the outdoor equilibrium fraction, as
a function of distance, for an assumed wind speed. Our outdoor
equilibrium fraction values are calculated on the assumption that the
radon has been released at the center of the pile and travels at an
average windspeed of 6.5 mph. The release location is actually
distributed over the entire pile, and the windspeed is distributed over
a range of values. Therefore, these assumptions tend to slightly
underestimate the equilibrium fraction close to the source. Depletion
processes, such as dry deposition or precipitation scavenging, will
remove some decay products, so complete equilibrium with the radon will
seldom, if ever, be reached.
When radon enters a structure, it remains for a mean time that is
inversely proportional to the ventilation rate. Hence, the building
entilation rate becomes an important factor affecting further changes
in the equilibrium fraction. This value can also be affected by other
considerations, such as the indoor surface-to-volume ratio and the dust
loading in indoor air. We here assume a 70-percent equilibrium
fraction for the indoor radon and decay products.
We have assumed that, on the average, Americans spend
approximately 75 percent of their time indoors, mostly in their homes
(Moa76, Oa72). We have weighted the indoor and outdoor equilibrium
fractions for a given location by factors of 0.75 and 0.25
respectively, to estimate an average value for calculating exposure to
radon decay products from a specific pile. Since indoor exposure is
dominant, this average equilibrium fraction does not depend strongly on
the distance from the tailings pile.
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The Population at Risk
We used 1970 census data to estimate the population distribution
near each of the piles. For local and regional estimates we used
census enumeration district data. These districts vary greatly in
physical size; they are generally small in urban areas and large where
the population is sparse. Occasionally, census data are not adequate
to estimate the local population. We have used supplementary data
sources for our population estimates in those instances (Sw81). These
population estimates are based on residential data only. We have not
attempted to project local population changes between 1970 and 1980
because the data available are inadequate.
Population data for distances greater than 50 miles are based on
1970 census data for cities, counties, and states and assume a
continental U.S. population of 200 million persons. A projected 1980
continental population of 220 million would increase the collective
exposures and corresponding total impact by about 10 percent.
4.3.3 Exposure to Gamma Radiation from Tailings Piles, Windblown
Tailings, and Misuse of Tailings
Many of the radioactive materials in tailings piles emit gamma
radiation. Unlike alpha radiation, which must originate within the
body to become hazardous, gamma radiation can penetrate both air and
tissue up to considerable distances. Near the edge of a pile, gamma
radiation can be much larger than the background level in uncontami-
nated areas. The gamma radiation from a pile, however, decreases
rapidly with distance; at more than a few tenths of a mile from most of
the inactive tailings piles, the increase cannot be differentiated from
the normal background, which is 80 to 100 mrem/y.
Levels of gamma radiation from an uncovered pile depend on the
amount of radium in the tailings sands and slimes and how these are
distributed within the pile. The radium content of processed ore may
also vary during the milling operation.
Field measurements indicate that on top of a pile, gamma radiation
levels range up to 4000 to 8000 mrem per year (FB76-78, FB81). This is
much higher than Federal guidance for nonrestricted areas, where the
radiation protection guide is 500 mrem/y for an identifiable individual
and 170 mrem/y for persons not being individually monitored (FRC60).
Areas adjacent to piles and contaminated by windblown tailings
sometimes show increased gamma radiation levels as high as 500 mrem/y
or more, and levels of from 100 to 200 mrem/y are common (Do75).
Increased levels of gamma radiation may also occur on open lands,
due to the misuse of tailings as fill or for other purposes. Natural
or contaminated soils with radium concentrations of 5 pCi/g through a
depth of several feet can produce gamma radiation exposure rates of
about 80 mrem/y (NP76) . Exposure rates are proportionately higher or
47
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lower for other radium concentrations and decrease as the layer of
radium-containing material becomes thinner or is covered over by other
materials.
4.3.4 Exposure to Radioactivity and Toxic Materials from a Tailings
Pile through Water and Food Pathways
Airborne transport of tailings, with subsequent deposition on
ground where food crops or feeds are grown, and the transport or
leaching of tailings by water used for drinking or irrigation can lead
to human exposure to radioactive and toxic substances. The degree of
detail with which we can treat these potential pathways varies. The
food pathway for radioactive materials blown from a pile has been
modeled in considerable detail (NRC79). This generic model is
conservative in that it assumes the sole source of the diet is locally
grown food and feeds. Modeling of water pathways requires
site-specific data on sources and uses of water. As yet, the existence
of actual water pathways for radioactive and toxic materials from
inactive tailings piles has not been verified, so we discuss these
pathways in general terms only. The food pathway for toxic materials
has not been investigated in the field but could exist close to a
pile. We have analyzed this pathway by assuming that toxic chemicals
and radioactive isotopes are transported simultaneously in tailings
particles.
Water Pathway for Radioactive Materials
Significant contamination of ground water or flowing surface water
has not been confirmed at any of the designated inactive tailings
sites. However, for unstabilized (i.e., uncovered) tailing piles,
tailings could contaminate nearby surface and ground water. Wind
erosion, floods, tailings slides into adjacent streams, seepage through
the pile, and runoff of rainwater are all potential routes for surface
water contamination. However, quantities of radioisotopes washed or
leached into flowing surface waters could be so dispersed and so
rapidly diluted that it is unlikely that surface water flow would ever
pose a significant health problem, except through major disruption of
piles by a flood.
Ground water contamination could occur when water seeps from
tailings into an underlying aquifer (a water-bearing layer of permeable
rock). Since people may draw water from a single underground aquifer
at many different places, the potential for exposure depends on the
hydrology between the points of contamination and use. Except in very
coarse or cracked media, through which contaminants flow relatively
unimpeded, the concentrations of contaminants reaching ground water are
likely to be reduced along the flow path by mixing, by absorption, by
adsorption, and by ion exchange with the ground material. The level of
user exposure to contaminated ground water depends on the amount drunk,
as well as on the level of contamination. The total amount consumed
depends, in turn, on the palatability and quality of the water, the
purpose for which it is used, and the number of users.
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There is little data on actual behavior of contaminants in ground
water on which to base conclusions on the effects of the factors just
cited. Available data indicate that some private wells in the Grants
Mineral Belt in New Mexico (Ka76) are contaminated with radioactive
materials to concentrations exceeding the National Interim Primary
Drinking Water Regulations that apply to community water systems
(EPA76b). However, it is not known if this contamination is due to
seepage during the active phase of nearby tailings piles or to
continuing contamination by inactive piles.
The NEC model for ground water contamination suggests that
radionuclides from active tailings will travel slowly and that the
concentration of contaminants in the ground water does not drop off
rapidly (NRC79). Therefore, we believe that the small amounts of
material that might be leached from inactive tailings are likely to
constitute a hazard, close to the site of their disposal, unless the
surfaces of the piles are effectively stabilized.
In summary, there is no firm evidence that radioactive
contaminants leached from inactive tailings are a general problem.
Instead, the possibility of such contamination should be considered on
a site-specific basis.
Water Pathway for Toxic Materials
There is also no confirmed case of water contamination by toxic
chemicals at the designated inactive mill sites. All of the preceding
general statements on pathways for radioactive elements apply to toxic
substances as well. To assess the potential for a problem at specific
sites, chemical and hydrological characteristics can be used to
identify substances most likely to enter and be carried through ground
water. However, different specific substances will be present at each
site, depending on the local geology and the nature of the tailings.
For example, some organic compounds—amines, kerosene, and higher
alcohols—are present in tailings from acid-leach mills. But the main
long-term potential ground water hazard is from leached inorganic toxic
substances.
Movement of contaminants through soil to ground water depends on
complex chemical and physical properties of the underground environment
and on local climatic conditions, such as precipitation and
evaporation. Chemical and physical processes in the subsoil remove a
portion of some contaminants from water passing through it. However,
some contaminants (e.g., selenium, arsenic, and molybdenum) can occur
in forms that may not be removed.
While not enough information is available to estimate the chance
that toxic substances from inactive tailings will move through water to
expose people, some migration of these substances in ground water near
tailings piles has been observed (Ka76). Studies of leaching at
tailings piles (Dr78) and leachates from municipal land fills (EEA78d)
49
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help determine which substances generally will be relatively mobile or
immobile and which will have a mobility varying with local conditions
(EEA78e). Limited studies of pollutant migration into ground water
near tailings piles indicate which elements will be most mobile (see
below and FB76-78, Ka76, DA77). However, there has been no systematic
study to establish the magnitude of ground water contamination for
tailings at either active or inactive sites.
Based on available information, chromium, mercury, nickel,
arsenic, beryllium, cadmium, selenium, vanadium, zinc, and uranium have
a high probability of being mobile in water pathways under certain
conditions (EIA78d, Dr78). Lead, radium, and polonium are not
predicted to be mobile in water pathways, but they appear to be mobile
at some locations (see Table 3-4). Experimental data on the mobility
of other toxic elements are not available. Therefore, conservative
assumptions should be used for ions that are generally mobile, such as
nitrate, chloride, and sulfate. Certain anions (e.g., arsenic,
manganese, molybdenum, and selenium) and organic complexes of trace
metals may also be relatively mobile, although confirming field data
are extremely limited.
In summary, toxic elements contamination of standing surface water
in the immediate vicinity of tailings could cause wild or domestic
animals drinking such water to develop acute toxic effects. However,
contamination of flowing surface water should not cause such a problem
because of normal dispersion and dilution. Finally, there are no data
showing significant ground water contamination from inactive tailings
piles and no adequate models to predict how such contamination will
travel, if it occurs. Ongoing studies supported by the Department of
Energy may provide a basis for assessing the potential hazard of ground
water contamination from inactive piles, but there is no existing basis
for assuming a health risk for this pathway.
Food Pathway for Radioactive Materials
Windblown tailings can deposit directly on plants, on the ground,
or on surface waters used for irrigation. Any of these events can lead
to contamination of crops. Persons eating these crops will absorb part
of the radioactive material. Animals eating these crops as feed will
absorb part of the radioactive material some of which will be deposited
in tissues or milk. Persons ingesting milk or meat from these animals
will also, in turn, absorb part of the radioactive material.
The NRC has developed a model (NRC79) to estimate the amount of
radioactive material in tailings that becomes airborne, is deposited
directly on plants or on the ground, and enters the food pathway. This
model considers meteorological factors, particle sizes, deposition
rates, and transfers from soil to plants, animals, and milk and from
food to humans. In the NRC model, the overall amount of radioactivity
reaching humans in small. The transfer coefficient from soil to the
edible portion of most food crops (Bvi) is assumed to be about 0.02
50
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for radium and 0.002 to 0.004 for uranium, thorium, and lead. Potatoes
are an exception; the coefficient for radium is 0.003. The transfer
coefficient from soil to pasture crops is about 0.07 for radium and
lead and about 0.002 to 0.004 for uranium and thorium. Further
discrimination occurs in animals. The concentration ratios for
radionuclides transferred from feed to milk or meat is between 0.01 and
0.15 (except the milk-to-feed ratio for thorium which is 0.003). The
overall concentration ratio for material transferred from soil-to-feed
crops to milk-or meat is the product of the soil-to-plant transfer
coefficient and the milk or meat-to-feed concentration ratio. These
values range from 0.000001 for the thorium milk-to-soil concentration
ratio to 0.01 for the radium meat-to-soil concentration ratio. In
general, the concentration in meat or milk is much less than 1 percent
of the soil concentration. Humans also discriminate against uptake of
these radioactive materials; only 0.01 percent of thorium and 10
percent, 20 percent, and 8 percent of uranium, radium, and lead,
respectively, are absorbed through the gastrointestinal tract.
Using this model, NRC calculated expected radionuclides intake and
radiation doses from food pathways for individuals and populations
between 1 and 80 kilometers from the NRC model mill. (!) Using this
data on individuals we estimated the regional impact of the food
pathway for windblown tailings and for deposition of lead-210 and
polonium-210 from the decay of radon from the tailings. The results of
this analysis are given in Section 4.5.2. No attempt has been made to
model the food pathway for radioactive materials via irrigation water.
This pathway should not increase the estimated doses significantly
since the collecting area of surface waters in the vicinity of inactive
tailings is small compared to any realistic total cultivated deposition
area. Moreover the transfer from water to soil to food will be less
than the direct transfer from soil to food*
Food Bathway for Toxic Materials
The processes discussed under the food pathway for radioactive
materials should apply equally well for toxic materials. Since the
airborne transport and deposition of tailings are governed more by the
size and density of the tailings particle than by their composition,
the toxic elements from tailings should be distributed in the
environment in the same way as the radioactive particles. No
measurements have been made of the movement of toxic elements from
(•'-'The NRC analysis for the ingestion pathway is conservative for
several reasons. It assumes that all food eaten is locally produced.
The transfer coefficient of radium from feed to meat (0.003 day/kg) is
also larger than usually assumed (EJft78a, McD79). For the final GEIS
(NRC80), NRC has revised the transfer coefficients for radium and lead;
they are generally less than those used in the draft GEIS (NRC79) and
would reduce ingestion pathway radionuclide intakes accordingly.
51
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tailings through food pathways. As a first approximation, therefore,
we assume that the ratios of concentrations of elements are the same at
any location where windblown tailings are deposited as they are in the
tailings pile.
For example, at the Slick Rock, Colorado, pile the average
concentration of radium is 784 pCi/g; of lead, 1250 pptn; and of
mercury, 109 ppm (see Appendix C). Where the concentration of
windblown tailings is 5 pCi/g of earth, the expected earth concentration
of lead would be 8 ppm and of mercury, 0.7 ppm. A person eating crops
grown on this contaminated land might be exposed to levels near to
those that are potentially toxic to humans (see Appendix C). These
relationships of toxic to radioactive elements in the food chain must
be evaluated on a site-specific basis because of the great variability
in concentrations of elements in the various inactive piles. However,
if an effective cover is employed for stabilization, this pathway
should not exist.
4.4 Estimates of Health Risks from Radioactive and Toxic Materials
In this section we develop the. risk estimates we use for the
principal radiological and toxicological impacts from tailings.
4.4.1 Rjs_k of Lung^Cancer from Inhaling Radon Decay Products
The high incidence of lung cancer mortality among underground
miners is well documented (EPA79b, Ar79, Ar81). Uranium miners are
particularly affected, but lead, iron, and zinc miners exposed to
relatively low levels of radon decay products also show an increased
lung cancer mortality that correlates with exposure to radon decay
products. The type of lung cancer most frequently observed in the
early studies, moreover, is relatively uncommon in the general
population.
Risk estimates for the general public based on these studies of
miners are far from precise. First, and most important, the relatively
small number of miners at risk injects considerable statistical
uncertainty into estimating the number of excess lung cancer cases (see
Figure 4-2). Second, although the cumulative lifetime exposure in
contaminated buildings can be comparable to that of some miners, most
of the miners studied were exposed to much higher levels of radon decay
products than usually occur in the general environment. Third, the
exposure levels are uncertain. Fourth, significant demographic
differences exist between miners and members of the general public—the
miners were healthy males over 14 years old, many of whom smoked.
However, information from the studies of miners can provide useful
estimates, if not precise predictions, of the risks to the general
population from radon decay products.^'
(1) See "Indoor Radiation Exposure due to Radium-226 in Florida
Phosphate Lands" (EPA79b) for greater detail of such an analysis.
52
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cc
<
UJ
80
70
§ 60
oc
UJ
O
O
z
D
_l
UJ
CO
D
m
50
40
30
20
10
Ai
J(
O CZECH-URANIUM
D SWEDEN-LEAD, ZINC (A), IRON (R,J)
A UNITED STATES-URANIUM
t CANADA-URANIUM
I 95% CONFIDENCE LIMITS
RD
I
I
I
100 200 300 400 500
CUMULATIVE WORKING LEVEL MONTHS
600
700
FIGURE 4-2. EXCESS FATAL LUNG CANCER IN VARIOUS MINER GROUPS
BY CUMULATIVE EXPOSURE (Ar79).
53
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Since the miners being studied have not all died, their eventual
excess lung cancers must be projected from current data by using
mathematical models. There are two ways to use the observed frequency of
lung cancer deaths among the exposed miners to estimate the risk from
inhaling radon decay products over a person's lifetime. One, commonly
called the relative-risk model, yields the percent increase in the normal
incidence of cancer per unit of exposure. The other, called the
absolute-risk model, yields the absolute numerical increase in cancers
per unit of exposure. In the relative-risk model it is assumed that the
increased risk is proportional to the age-dependent natural incidence of
the disease for each year an individual remains alive following
exposure. In the absolute-risk model it is assumed that the added risk
is independent of natural incidence, i.e., the risk is constant each year
an individual remains alive following exposure.
As a basis for calculating estimates using the relative-risk model,
we have concluded (EPA79b) that a 3-percent increase in the number of
lung cancer deaths per WLM is consistent with data from the studies of
underground miners. However, because of the differences between adult
male miners and the general population, we have estimated (EPA79b) that
the risk to the general population may be as low as 1 percent or as high
as 5 percent. For our absolute-risk estimates, we use the estimate of 10
lung cancer deaths per WLM for 1 million person-years at risk reported by
the National Academy of Sciences (NAS76). Both of these risk
coefficients are used here to examine the potential consequences of
lifetime exposure to radon decay products. Unless we state otherwise, we
estimate excess cancer fatalities, i.e., those caused by elevated
radiation levels that are in addition to those from other causes.
To estimate the total number of lung cancer deaths from increased
levels of radon in the environment, we have used a life-table analysis of
the additional risk due to radiation exposure (Bu81). This analysis uses
the risk coefficients just discussed. It also takes into account the
time a person is exposed and the number of years a person survives other
potential causes of death, based on 1970 U.S. death-rate statistics. The
result is expressed as the number of premature lung cancer deaths that
would occur due to lifetime radiation exposure of 100,000 persons. We
assume, further, that injury caused by alpha radiation is not repairable,
so that exposed persons remain at risk for the balance of their lifetimes,
Using the relative-risk model, we estimate that a person exposed to
0.01 WL (.27 WLM/y) over a lifetime incurs a 1.7 percent (1 in 60)
additional chance of contracting a fatal lung cancer. [This is
equivalent to a lifetime risk of 1.2 percent (1 in 80) estimated for a
residential situation where a person spends 75 percent of the time
exposed to 0.01 WL. This results in 0.20 WLM/y of exposure and was the
basis for our risk estimate discussions in Section 4.2 and 4.3 of the
Draft Environmental Impact Statement and in EPA79a and EPA79b.] This
estimate was made assuming children are no more sensitive than adults.
If exposure to radon decay products during childhood carries a three
54
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times greater risk, this estimated lifetime relative risk would increase
by about 50 percent (EPA79a-b). Using a similar life-table analysis and
an absolute-risk model, we estimate that a person exposed to 0.01 WL over
a lifetime incurs a 0.7 percent (1 in 140) additional chance of
contracting a fatal lung cancer. (This corresponds to 0.6 percent for
exposure 75 percent of the time.) Again, equal child and adult
sensitivities are assumed (EPA79a-b). For comparison, a life-table
analysis for the same population not exposed to excess radiation yields a
2.9-percent chance of lung cancer death. Therefore, our relative
(absolute) risk estimate for lifetime exposure to an increment of 0.01 WL
corresponds to a 60 percent (20 percent) increase in the expectation that
a person will die of lung cancer.
Even though, under either of these models, the risk of radon-induced
lung cancer varies with age, it is sometimes convenient to express these
risks on an average annual basis. We have calculated a person's average
annual risk from a lifetime of exposure by dividing the lifetime risk
estimates given above by an average lifespan of 71 years.(D Based on
the risk models and assumptions just described for lifetime exposure we
estimate an average of 1.0 to 2.4 lung cancer deaths per year for each
100 person-working-levels of such exposure. "Person-working-levels" is
the population's collective exposure; that is, the number of people times
the average concentration of radon decay products (in working levels) to
which they are exposed.
For the entire U.S. population, the estimated number of cancers is
larger using the relative-risk rather than the absolute-risk model, but
this does not hold for all locations because the lung cancer rate varies
considerably in different parts of the country. Therefore, we based our
relative-risk estimate for each inactive site on the lung cancer death
rate for the state in which the site is located. Lung cancer death rates
are lower than the national average in several of the states where
inactive tailings sites are located, so at some localities the absolute
risk is greater than the relative risk.
Radiation risk can also be stated in terms of years of life lost due
to cancer death. In the relative-risk model, the distribution of ages at
which lung cancer caused by radiation occurs is the same as that for all
lung cancer in the general population. Since lung cancer occurs most
frequently in people over 70 years of age, the years of life lost per
fatal lung cancer—14.5 years on the average—is less than for many other
fatal cancers. The absolute-risk model assumes that lung cancer
fatalities occur at a uniform rate throughout life and, therefore, each
fatality reduces the lifespan by a larger amount—an average of 24.6
years. Thus, even though the estimated number of lung cancer
fatalities
(1'Note that this is not the same as applying the risk coefficient for
71 years, since the life-table analysis accounts for other causes of
death.
55
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using the relative-risk model (nationwide) is nearly twice that using the
absolute-risk model, estimates of the total years of life lost in the
exposed population are nearly the same.
Because we used recent population data, our assessments are for
current conditions around tailings piles. If the population lifestyle,
medical knowledge, and other patterns of living affecting mortality
remain unchanged, then these rates of lung cancer death could persist for
the indefinite future. We have not attempted to assess the effects of
future change, which may either increase or decrease our risk estimates.
It is prudent, we believe, to assume that estimated risks based on
current data could persist over the indefinite future.
4.4.2 Cancer and Genetic Risks from Gamma Radiation
Gamma radiation from tailings exposes the entire body so that all
organs are at risk. The estimated frequency of fatal cancer and serious
genetic effects due to a lifetime exposure of 100 mrem per year is listed
in Tables 4-1 and 4-2. People who live or work near tailings piles will
incur risks from long-term exposures in proportion to the excess of their
average lifetime annual dose rate above normal background (approximately
100 mrem per year.)
4.4.3 Risks from Toxic Materials
Toxic materials have been considered in this EIS if they are in
substantially greater concentration in tailings than in native rocks or
soils or in a relatively mobile form (anionic or cationic). We have
included materials that are harmful to livestock and plants as well as
those potentially affecting humans directly. Evaluating the potential
risks from nonradioactive toxic substances in tailings requires different
methods from those used for radioactive substances.(l) with
nonradioactive toxic materials, the type of effect varies with the
material; the severity of the effect—but not its probability of
occurring—increases with the dose. Moreover, because the body can
detoxify some materials or repair the effects of some small doses, often
no toxic effects occur below a threshold dose.
We cannot construct a numerical risk assessment for nonradioactive
toxic substances because we do not have enough information. We can
however, qualitatively describe risks of toxic substances in terms of
their likelihood of reaching people (or animals, or agricultural
products), concentrations at which they may be harmful, and their toxic
effects.
nonradioactive substances can induce cancer in experimental
animals (Go77, Ve78). However, for nonradioactive substances found in
uranium mill tailings, we do not*feel that dose-response relationships
adequate for estimating such risks for oral intake have been developed.
56
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TABLE 4-1. ESTIMATED RISK OF FATAL CANCER FROM LIFETIME
EXPOSURE TO GAMMA RADIATION AT 100 mREM/Y
Risk Model
(a)
Relative
Absolute
Lifetime risk of fatal cancer
Life expectancy lost per fatality(b)
Average life expectancy lost
per exposed person
5 in 1000
14 years
24 days
0.8 in 1000
23 years
7 days
(a'Chronic lifetime exposure; the exposure and the risk from this
exposure is assumed to continue until death.
1970 population statistics used for this analysis yields an
average life span of 70.7 years.
TABLE 4-2. ESTIMATED RISK OF SERIOUS GENETIC ABNORMALITIES
FROM LIFETIME EXPOSURE OF THE GONADS TO 100 mREM/Y^a'
First
Generation
All Succeeding
Generations
Risk per 1000 live births
0.04 to 0.6
0.14 to 5
(^Currently, 60 to 100 serious abnormalities per 1000 live births
(not related to excess radiation) are observed in the United
States. We calculate the risk from radiation using the observed
distribution of ages of parents when these live-born are con-
ceived.
57
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No acute effects—death in minutes or hours—could occur except by
drinking liquid directly from a tailings pond. Severe sickness, or death
within days to weeks, from the use of highly contaminated water is
possible, but unlikely.
Chronic toxicity from the continuous consumption of contaminants at
low concentrations could be a problem. Toxic substances can accumulate
slowly in tissues, causing symptoms only after some minimum amount has
accumulated. Such symptoms of chronic toxicity develop slowly, over
months or years.
In Tables 3-2 and 3-3 we listed many chemical elements and ions that
have been found in tailings piles. Many of these occur in tailings in
only slightly higher concentrations than in background soils, and they
also have low toxicity when taken orally (Ve78). The following elements
are in this category: lanthanides, including cerium, europium, lanthanum,
and terbium; silicates; and zirconium, scandium, boron, gallium, and
aluminum. Some other elements may be in elevated concentrations in
tailings, but they, too, are not very toxic. These include copper,
manganese, magnesium, cobalt, iron, vanadium, zinc, potassium, chloride,
and sulfate. Some elements and ions at concentrations well below levels
toxic to humans and animals will cause water to have an objectionable
taste and color. Examples are iron, copper, manganese, chloride, and
sulfate.
Other substances are both present in tailings and are regulated
under the National Interim Primary Drinking Water Regulations (NIPDWR).
Listing in the NIPDWR is an indication of a significant need to limit
direct human consumption of these substances. The NIPDWR cover the
following elements: arsenic, barium, cadmium, chromium, lead, mercury,
nitrate, selenium, and silver. The toxicologies of these substances are
discussed in Appendix C. Molybdenum is both toxic and present in
tailings in elevated concentrations; its toxicity is also discussed in
Appendix C. Appendix C also discusses both the chemical and radiological
toxic effects of ingesting radium, thorium, and uranium. Tailings are
not known to be significant sources of other toxic materials regulated
under NIPDWR, such as organic substances, microbiological organisms, and
man-made radioactivity.
4.5 Estimated Effects on Health due to Tailings
Health is affected when tailings are removed from a pile and misused
and when there is radon emission and gamma radiation from a pile.
4.5.1 Effects from Misuse of Tailings
When tailings are used in building construction there can be serious
risks to the health of those who live in such buildings. The Grand
Junction experience is an example of what can happen when this kind of
misuse occurs. There, about 70(f buildings are contaminated with enough
58
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tailings to increase indoor radon decay product levels by 0.01 WL or
more; a few houses have levels higher than 0.5 WL. If it is assumed that
the useful lifetime of these buildings is 70 years, we estimate about
additional 70-150 lung cancers would occur if remedial measures were not
taken.
The estimated risks to individuals exposed to these high levels of
radon decay products are very large. For persons living in a house with
a concentration of 0.1 WL, the potential excess lifetime risk of lung
cancer is 0.5 to 1 chance in 10.
Other misuses of tailings, e.g., tailings used in gardens or
underneath detached buildings, can cause effects on health, but these
cannot be estimated accurately. The risks depend on the particular way
in which the tailings are used, because effects on health may be due to
gamma radiation, ingestion of radionuclides through food chains, or
inhalation.
4.5.2 Effects of Radon Emissions from Tailings Piles
We have separated the discussion of radon from tailings piles into
two parts. The first concerns exposure of individuals living very close
to the piles, and exposure of populations in the local environment
(within 50 miles of the tailings piles). The second deals with exposure
of the population of the rest of the North American continent, and world-
wide populations.
Local and Regional Populations
Detailed information is needed to determine the exposure due to
radon decay products to a local population. An accurate calculation of
the collective exposure from a particular pile would require, besides the
number of people exposed, the site and ventilation characteristics of
each person's residence and work place, the length of time a person is at
each place, and the average annual distribution of wind speed and
direction. These data are unavailable for the inactive sites.
We have estimated local and regional exposure at 6 of the 24
inactive sites (SW81). Although this sample is limited, it includes all
important urban sites except Canonsburg, Pa. The remaining piles are in
remote areas and collectively have only about one tenth of the local and
regional population exposures that these six piles collectively have.
The methods used to estimate exposures were described in Section 4.3.2.
Although we have ignored population changes since 1970, a future increase
in population at several of the urban sites seems likely.
In Table 4-3 we summarize the results for the six sites in terms of
estimated excess lung cancer deaths and average days of life loss per
exposed person. The estimated number of lung cancer deaths associated
with a tailings pile is highly variable, being highly dependent on the
59
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TABLE 4-3. ESTIMATED RISK OF FATAL LUNG CANCER TO LOCAL AND REGIONAL POPULATIONS
DUE TO THE LIFETIME EXPOSURE TO THE RADON FROM UNSTABILIZED URANIUM TAILINGS PILES
Absolute-Risk Model Relative-Risk Model
Local , •, ., ^ Average Life Loss / ^ Average Life Loss
Population at Risk Fatal Cancers Per Exposed Person Fatal Cancers Per Exposed Person
(Size) (Number/IQOy) (days) (Numb er/ IQOy) L^^LL
Salt Lake City, Utah
Local population 79 1.4 72 0.8
(361,000)
Regional population 5 0.06 4 0.03
(494,000)
Mexican Hat, Utah - - -
Local population
(None permanent)
Regional population 0.05 0.02 0.05 0.01
(14,100)
Grand Junction, Colorado
Local population 18 2.9 29 2.6
(39,800)
Regional population 0.2 0.03 0.2 0.03
(30,600)
Gunnison, Colorado
Local population 2 2.5 3 2.3
(5,060)
Regional population 0.01 0.004 0.02 0.003
(17,060)
Rifle, Colorado (Newer pile)
Local population 1 1.7 1 1.5
(2,700)
Regional population 0.02 0.003 0.03 0.003
(35,900)
Shiprock, New Mexico
Local population^) 32 41
(7,200)
Regional population 0.1 0.01 0.1 0.007
(63,600)
population, those people within 7.5 miles; regional population, those people between 7.5
and 50 miles.
ife loss per fatal cancer—15 years.
ife loss per fatal cancer—25 years.
Within 10 miles.
60
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population density in its immediate vicinity. The estimated number of
fatal cancers for Utah residents based on the absolute-risk model is
greater than that based on the relative-risk model. This is because the
lung cancer death rates in Utah are comparatively low. The risks listed
in Table 4-3 are based only on direct radon emissions from the tailings
pile and include no additional risk from any offsite tailings material
used in construction or elsewhere.
Effects on health were estimated separately at Canonsburg, Pa.,
because most of the radon exposure is received by persons working at the
site. We estimate the excess risk to these workers and to the local
population as 17 to 29 fatal lung cancers per 100 years, for the
absolute-risk and relative-risk models, respectively.
The excess risk to people due to exposure to radon decay products
depends on their distance from the pile. Table 4-4 gives calculated
exposures and estimated excess risks to individuals for lifetime
residency, as a function of distance from a theoretical pile with a radon
emission rate of 2,000 curies per year. The decay product concentrations
are based on a dispersion factor that depends on the area of the pile out
to a distance of several pile diameters. Beyond that distance the
theoretical pile can be considered as a point source for the purpose of
estimating concentation levels. The estimates for this pile are based
upon the absolute-risk model only since relative-risk estimates are site
specific.
Ford, Bacon, and Davis have published plots of the outdoor radon
concentration vs. distance from the edge of the pile for the sites they
studied (FB76-78). We have used those data (identified by Ford, Bacon,
and Davis as from measurements) together with estimates of distance from
the pile to the nearest residents (Ga82) to estimate the exposure level to
the nearest residents at several of the sites. Essentially, the decay
product exposure level assumes an indoor radon concentration equal to the
outdoor concentration and an average equilibrium fraction of 0.7. The
estimated exposure levels and calculated lifetime risks for residents near
several tailings piles are shown in Table 4-5. Since these are
site-specific estimates based on measured values which include background
radon, they are not directly comparable to those in Table 4-4. Estimates
in Table 4-5 of the excess individual risk for lifetime exposure are as
high as a l-in-25 chance of death from lung cancer.
In Table 4-6, we provide estimates of the risks from naturally
occurring radon decay products found in homes that are not near mill
tailings or any other specifically identified radon source. National data
on radon decay products in homes are scanty and vary widely among
individual houses. These estimates are based on the assumption that the
average radon decay product concentration is 0.004 WL in homes and that
they are occupied 75 percent of the time. This assumed average level of
radon decay products is based on recent data on 21 houses in New York and
New Jersey (Ge78) and on 26 houses in Florida (EPA79b) and is consistent
61
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TABLE 4-4. EXCESS RISK OF FATAL LUNG CANCER DUE TO LIFETIME
RADON DECAY PRODUCT EXPOSURE AS A FUNCTION OF DISTANCE FROM A
THEORETICAL TAILINGS
Distance from
Center of Pile
(miles)
0.2
0.5
1.0
2.0
5.0
10.0
20.0
50.0
Dispersion
Factor
(s/m3)
1.1 x 10-5
2.4 x 10~6
5.7 x 10~7
2.1 x 10~7
4.4 x 10~8
1.1 x 10~8
2.0 x 10~9
5.7 x 10-10
Radon Decay Product
Concentration
(WL)
3.8 x ID"3
8.5 x 10~4
2.1 x ID"4
8.1 x ID"5
1.9 x 10~5
5.2 x HP6
9.9 x ID"7
2.8 x 10~7
Lifetime Excess Risk
(Chances per
2,700
600
150
58
14
4
0
0
Million)
.7
.2
'a'Tailings pile parameters:
Radon release rate: 2,000 Ci/y.
Area: 31 acres.
Uniform radium concentration: 500 pCi/g.
Radon emission rate: 1 pCi/m^s radon per pCi/g of radium.
^"'Absolute-risk model of fatal lung cancer from lifetime exposure to radon
decay products. The expected lung cancer mortality for a stationary
population with 1970 U.S. mortality rates is 29,000 per million (EPA79a-b).
with data obtained in other countries (UN77). For comparison, these
risks are about 10 percent of the expected lifetime risk of lung cancer
death from all causes (0.029) in a stationary population having 1970
U.S. lung cancer mortality rates.
Effects on the U.S. Population
Radon emissions from tailings piles may affect the health of
populations beyond 50 miles from tailings piles. Estimates of lung
cancer deaths among persons living more than 50 miles from specific
inactive tailings piles are listed in Table 4-7. The aggregate effect
on persons living more than 50 miles from these piles is summarized in
Table 4-8. These results are estimates of the total risk over 100
years for an exposed population of 200 million persons.
The Canonsburg, Pa., site was not included because our dispersion
estimates were developed for western sites only. The effect on
continental populations due to Canonsburg is not likely to be larger
62
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than that from a western pile. Thus, the aggregate effects listed in
Table 4-8 are not significantly affected by this omission.
Effects from Long-Lived Radioactive Decay Products of Radon
The long-lived decay products of radon (beginning with lead-210)
are also potential hazards (see Figure 3-1). The consequences of
eating and breathing long-lived decay products cannot be established
without site-specific information—on food sources, for example. The
only detailed study is that provided for a model site in the NRG Draft
GEIS on Uranium Milling (NRC79). However, the NRC results are likely
to overestimate exposures at many of the inactive sites. We use the
results of the NRC analysis here only to identify important exposure
routes and to compare their importance to that of the short-lived decay
products of radon. These results should not be taken as quantitative
estimates of the actual risk at specific inactive sites.
The NRC model uranium mill and tailings pile is located in a
sparsely populated agricultural area dominated by cattle ranching. The
population in this region is assumed to produce all of its own food,
which is unlikely. For tailings near urban areas, with a large number
of people living close to the tailings pile, complete dependence on
locally supplied food is even less likely.
The five sources of exposure in the NRC analysis are shown in
Table 4-9. The largest risk is from breathing short-lived radon decay
products; it is more than 10 times greater than the next highest risk
from ingesting windblown tailings through vegetables and meat.
Lead-210 and polonium-210, formed in air through radon decay, are also
sources of risk through food and inhalation pathways. According to the
NRC analysis, the risk from each of these pathways equals about
one-hundredth of the risk from breathing short-lived radon decay
products. Persons living more than 50 miles from an inactive pile
would be less heavily exposed, and their risk would be considerably
below that indicated in Table 4-9. We conclude that the risks from
these pathways can be ignored compared to that from indoor short-lived
radon decay products.
4.5.3 Effects of Gamma Radiation Emissions from Tailings Piles
Gamma radiation exposure of individuals depends on how close to
the edge of a pile people live or work. The collective gamma radiation
dose depends on both the number of people exposed and their average
dose. In a few cases individual doses can be approximated from
available data, but generally this cannot be done without a variety of
detailed information, such as where people live and work and the amount
of shielding provided by buildings. Outdoor gamma radiation doses in
the vicinity of some tailings piles at inactive sites are summarized in
Table 4-10. In several cases, even the nearest residents are far
enough from the pile that they receive essentially no excess gamma
63
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TABLE 4-5. ESTIMATED RISK OF FATAL LUNG CANCER DUE TO
RADON FOR AN ASSUMED LIFETIME RESIDENCE NEAR SPECIFIC
TAILINGS PILES*3^
Location Risk of Lung Cancer (Chance per Lifetime)
(Distance from Pile s r^—i c ('~
and Exposure Level) Absolute-Risk ModeP Relative-Risk Model
Salt Lake City, Utah 0.03(d) 0.03
(0.05 mile, 0.045 WL)
Grand Junction, Colorado 0.03 0.04
(0.1 mile, 0.045 WL)
Durango, Colorado 0.02 0.03
(0.1 mile, 0.026 WL)
Rifle, Colorado 0.005 0.008
(0.5 mile, 0.007 WL)
Gunnison, Colorado 0.006 0.009
(0.5 mile, 0.008 WL)
(a'Radon decay product exposure levels are based on site-specific
outdoor radon concentrations (FB76-78).
(b^Life loss per fatal cancer—25 years.
(c/Life loss per fatal cancer—15 years.
risk of 0.03 is the same as 30 chances in a thousand.
TABLE 4-6. LIFETIME RISK OF FATAL LUNG CANCER DUE TO NATURALLY-
OCCURRING RADON IN RESIDENTIAL STRUCTURES(a)
Estimated Risk to an Individual
Absolute-Risk Relative-Risk
Model Model
Risk of lung cancer
(Chance per lifetime)
Life loss per fatality
(Years)
Average life loss per exposed person
(Days)
0.002
25
18
0.004
15
23
risk of 0.004 is the same a% 4 chances in 1 thousand.
(^Calculated on the basis of 0.004 WL, home occupied 75% of the time
and 1970 U.S. mortality rates (EPA79a-b). '
64
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TABLE 4-7. RISK OF FATAL LUNG CANCER TO THE U.S. POPULATION
DUE TO RADON FROM SPECIFIC TAILINGS PILES
(a)
Excess Risk of Lung Cancer
(Deaths per 100 Years)
Site of Tailings Pile
Absolute-Risk
Model
Relative-Risk
Model
Arizona
Monument Valley
Tuba City
Colorado
Durango
Grand Junction
Gunnison
Maybe11
Naturita
Rifle, Colorado^)
Slick Rock, Colorado(b)
Idaho
Lowman
New Mexico
Ambrosia Lake
Shiprock
North Dakota
Belfield
Bowman
Oregon
Lakeview
0.3
0.2
1
3
1
2
2
3
1
0.2
5
2
0.6
0.4
2
7
2
4
3
6
3
0.5
10
4
Texas
Falls City
Utah
Green River
Mexican Hat
Salt Lake City
Wyoming
Converse
Riverton
0.5
3
7
0.1
3
10
1
6.5
15
0.3
7
(a'Does not include effects within 50 miles of the site (see
Table 4-3), and assumes piles are not stabilized. Canonsburg,
Pa., site not included.
inactive piles.
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TABLE 4-8. RISK of FATAL LUNG CANCER TO THE U.S. POPULATION
DUE TO RADON FROM ALL INACTIVE TAILINGS PILES^a*
Estimated Risks to U.S. Population
Absolute-Risk ModelRelative-Risk Model
Lung cancers
(Number/100 years) 42 88
Life loss per fatality
(Years) 25 15
Average life loss per
exposed person
(Days) 0.0013 0.0017
'a'Canonsburg, Pa., site not included.
not include people living within 50 miles of the site, and
assumes piles are not stabilized.
TABLE 4-9. RISK of FATAL CANCERS TO REGIONAL POPULATIONS
DUE TO RADIONUCLIDES FROM INACTIVE TAILINGS PILES
(NRC Model Pile, Population at Risk - 57,000)
Estimated Risk of Cancer
Exposure Pathway _ (Deaths/y) _
Inhalation of short half-life
radon decay products 0.06(a)
Ingestion of radioactive
windblown tailings 0.004(b,c)
Inhalation of
lead-210/polonium-210
Ingestion of
lead-210/polonium-210
Inhalation of re suspended
tailings from open lands 0.00006^^
relative risk estimate.
estimate based on individual nuclide concentrations cal-
culated by NRC to prepare dose summary tables for the draft
GEIS (NRC79).
(c)particles containing U-238, U-234, Th-234, Th-230, Ra-226 ,
Pb-210, Bi-210 (See Figure 3-1).
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TABLE 4-10. RADIATION EXPOSURE TO NEAREST RESIDENTS
DUE TO GAMMA
Location of
Inactive Site
Colorado
Durango
Grand Junction
Gunnison
Rifle
Idaho
Lowman
New Mexico
RADIATION FROM INACTIVE TAILINGS
Location of Nearest Resident
Distance from Pile Edge
(miles)
0.1
0.1
0.5
0.25
1.0
PILES(a)
Gamma Radiation
Exposure^)
(mrem/y)
200-300
580
(c)
(c)
(c)
Ambrosia Lake
Pennsylvania
Canonsburg
Utah
Green River
Salt Lake City
Wyoming
Spook
1.5
0.04
0.15
0.05
1.5
(c)
150
(c)
465
(c)
(a'Ambient gamma radiation background at each site has been subtracted.
'^'Measured in air (Roentgens). At these energies continual exposure
to 1 mR/y gives an annual dose of 1 mrem.
No detectable increase above background.
TABLE 4-11. EXCESS RISK OF FATAL LUNG CANCERS DUE TO RADON
FROM ALL INACTIVE URANIUM MILL TAILINGS PILES
Population at Risk
Estimated Fatal Lung Cancer Risk (number/100 years)
Absolute-Risk Model Relative-Risk Model
People within 50
miles of any
People more than
50 miles from all
130
40
150
90
TOTAL
170
240
^'Summary of estimates given in Table 4-3, plus estimates for
Canonsburg, Pa.
'"'Summary of estimates given in Table 4-8.
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radiation. At others, a few residents are located close enough to
perhaps double the dose from gamma radiation that would occur without
the pile. In a few cases, the dose to the nearest resident may be
several times normal background levels. In most of these localities,
normal background due to penetrating gamma radiation is about 100 mrem
per year (FB76-78).
In summary, lack of information precludes detailed calculation of
the collective gamma radiation dose and risk to all persons living or
working near the inactive piles. The total impact, however, is small,
because the gamma-radiation intensity falls rapidly with distance from
the pile.
4.6 Summary
The most significant individual health risk caused by the inactive
tailings piles is that from inhaled short-lived radon decay products.
This arises for two reasons: misuse of tailings in and around buildings
and direct radon emission from the piles. Compared to the risk from
short-lived radon decay products, the other radiological risks are much
less significant. At most, they increase by 10 percent the risk
estimated for the regional population, and the additional risk to the
national population is much less. This incremental risk is small
compared to the uncertainty—at least a factor of two—in the estimated
risk for lung cancer deaths from indoor radon decay products.
The six sites in Table 4-3 represent all but one of the designated
sites in areas with relatively large local and regional populations.
The other inactive piles are either in remote areas or are small and do
not contribute much to the total risk. Summing the estimated fatal
cancers for these six sites gives our best estimates of the risk to
regional and local populations due to all inactive uranium mill tailings
piles. Our best estimate of the total risk to the continental U.S.
populations due to all inactive uranium mill tailings piles is made by
summarizing the values in Table 4j-7 . We summarize these risks in Table
4-11. Most risk is to people within 50 miles of the six sites, but the
aggregate risk to more distant people is significant.
The nonradioactive toxic substances present in an inactive tailings
pile and their potential impact on public health and the environment
must be determined for each site. Substances with the highest potential
for causing a health risk are those that can move through ground water
and that have the greatest toxicity. These include forms of arsenic,
barium, cadmium, chromium, lead, mercury, molybdenum, nitrate, selenium,
and silver. In addition, among radioactive substances, uranium is most
likely to be mobile in ground water, while radium and polonium are
possibly mobile.
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Chapter 5: METHODS FOR CONTROL OF TAILINGS PILES AND FOR
CLEANUP OF CONTAMINATED LANDS AND BUILDINGS
Our goal is to reduce the health risk from tailings by isolating
them from the biosphere. Remedial actions are usually needed in two
general areas: 1) at the tailings pile and near the pile where
tailings are scattered as a result of milling operations, and 2) at
other locations where tailings are found, including tailings used in
building construction and for fill, and wind-blown tailings on lands
near the mill site.
Section 5.1 contains a brief discussion of the objectives of
control measures for tailings piles, contaminated buildings, and lands
contaminated with tailings. In Section 5.2 we give a more detailed
discussion of the engineering and institutional controls that are
available for tailings piles. In Sections 5.3 and 5.4, we do the same
for contaminated buildings and lands, respectively.
5.1 Objectives of Remedial Methods
For tailings piles, the major objectives of control methods are to
provide effective long-term stabilization and isolation, to control
radon and gamma emissions from the tailings, and to protect water
quality.
The long-term integrity of remedial methods undertaken to achieve
these objectives is an overriding consideration. Because of the long
half-life of some of the radioactive materials in tailings, and the
permanent toxicity of some of the other contaminants, the risks due to
tailings will exist for hundreds of thousands of years. In order to
make judgements on the degree of health protection feasible for future
generations, we have assessed long-term durability and need for
periodic repair for each remedial method.
Long-term stabilization and isolation should do the following
things: 1) reduce the chance of human intrusion so as to prevent the
use of tailings as a construction material, as backfill around
structures, and as landfill; 2) protect the piles from natural
spreading by wind erosion and surface water runoff; 3) prevent
spreading by flood damage to the piles; and 4) prevent tailings from
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contaminating surface and groundwaters. Radon and gamma emission
controls prevent or inhibit such emissions from the piles. Water
quality controls prevent contamination of water through leaching of
radioactive or other hazardous materials from the tailings into surface
water, or groundwater aquifers.
For contaminated buildings, the major objectives are to reduce
radon decay product levels and (sometimes) to reduce gamma radiation.
For contaminated lands, the major objectives are to reduce gamma ray
exposure and to prevent high levels of radon decay products in any new
buildings. Remedial measures for land may also be required to protect
surface and groundwater, and to avoid exposure of man through food
chains.
5.2 Remedial Methods for Tailings Piles
Both active and passive remedial control methods for tailings
piles are available. Active controls require that some institution,
usually a government agency, have the responsibility for continuing
oversight of the piles and for making repairs when needed. Fencing,
warning signs, periodic inspection and repairs, and restrictions on
land use are examples of the measures that may be used. Passive
controls are measures of sufficient permanence that little or no upkeep
or active intervention by man is needed to maintain their integrity.
Passive controls include measures such as thick earth or rock covers,
barriers (dikes) to protect against floods, burial below grade, and
moving piles out of flood-prone areas or away from population centers.
Some measures may be either active or passive, e.g. thin earth covers
require maintenance, thick ones do not. Similarly, vegetative cover
that requires irrigation is a control requiring active (institutional)
maintenance, but the establishment of indigenous vegetation is a
passive means of control.
Active and passive controls for tailings can be classified into
two groups: those that are currently available and have a reasonable
likelihood of being successfully used, and advanced methods that
require further development and testing. The first group includes
earth and clay covers over tailings, plastic or clay liners between
tailings and underlying earth, and dikes or embankments around the
edges of tailings. The second group includes untested methods such as
covering tailings with asphalt or other impermeable barriers, moving
tailings to worked-out underground mines, solidifying tailings in
cement or asphalt matrices, and chemically separating radium and
thorium from tailings followed by solidifying and disposing of radium
and thorium in deep geologic formations.
Only available methods are considered in detail in this analysis,
since costs and performance can be reliably predicted for them. We
have, however, included a potential method using soil cement as a
control method in Chapter 6 and Appendix B. Advanced methods could be
used when they are shown to be effective and economical.
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In this section we describe specific methods to achieve
stabilization, reduce radon and gamma emissions, and protect water
quality. The longevity of these methods is discussed separately in
Section 5.2.5 because it is a major consideration. Advanced methods
are briefly reviewed in Section 5.2.6.
5.2.1 Stabilizing Tailings
Preventing Misuse of Tailings
Risks to health arise from uranium tailings (see Chapter 4) when
they are removed from processing sites and used in construction or as
fill around inhabited structures. There is real potential for this if,
as has happened at many piles, people identify a disposal site as a
resource area for sand. Tailings are a high grade sand that would be
ideal for use in construction or as fill if the material were not a
health hazard. This kind of misuse can be prevented by active methods
of control such as fences, inspections, disposal site ownership,
restrictions on land deeds, and by passive methods of control, such as
placing physical barriers around the tailings. Ideally, passive
barriers should be effective so that unusual effort would be required
to overcome them before the tailings could be removed and used.
Examples of barriers are thick earthen covers, heavy rock covers,
dikes, and below-ground burial.
The thickness of barriers needed to prevent unintentional
intrusion can be estimated. A variety of human activities involve
excavation to depths of 6 to 8 feet. Sewer and water pipes are buried
below the frost depth which may be 4 to 6 feet deep in cold climates.
Footings for foundations of houses with basements often are placed at
depths of 8 feet or greater, and this may imply needs for sewer pipes
at slightly greater depths. Graves are dug to 6 feet. Thus, an earth
cover used to provide passive protection for tailings piles should be
of substantial thickness; we estimate that a cover 10 feet thick would
prevent most casual intrusions into tailings.
Two controls that might encourage human degradation of control
methods are the use of small-sized rock for erosion protection, and
fences. Rock and fencing have intrinsic value and may be stolen,
especially at remote sites. The likelihood of this is difficult to
evaluate; however, it provides an argument in support of earthen
covers, which have little resource value, and heavy rock covers. The
theft of rock is assumed to be inhibited if the individual pieces are
large and difficult to handle (400 pounds or larger).
Preventing Erosion
Any covering will prevent the erosion of tailings as long as its
integrity is maintained. Both thin impermeable covers and thick earth
covers will prevent tailings from becoming windborne or waterborne.
When earth covers are used, the problem becomes that of protecting the
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earth cover from erosion. Rock or vegetation is usually used to
provide this protection.
Gully erosion of covers is caused by surface water runoff from
rain or snow. The cover is cut through, exposing tailings which are
then eroded by wind and water. Thin impermeable covers can be designed
to withstand gullying as can thick earthern covers having properly
graded slopes and rock or vegetation for surface stabilization.
Rock cover is a means of protecting underlying soil from erosion
by wind and water runoff. We distinguish between 3 types of rock
cover: riprap, rock, and rocky soil. Riprap generally refers to an
orderly placement of large rocks that have often been shaped to fit
together. It provides good protection against erosion and is also
effective in protecting against damage from floods. It is quite
expensive. In the control methods discussed in Chapter 6 and Appendix B,
we have specified the use of riprap for shielding embankments which
protect piles threatened by floods. We use rock to refer to a less
orderly placement of rocks that have not been shaped to fit together.
We specify its use for protecting the slopes and tops of piles from
erosion by wind and water runoff. Rocky soil refers to soil with
significant rock content. It is used as the top layer of earth cover
that is to be protected from erosion by vegetation, where it is feared
that the vegetation may fail. If the vegetation fails, erosion would
remove the fine grained soil particles, leaving a protective layer of
rock on the surface, protecting the underlying earth. We have
estimated that a 0.33 meter thickness of rocky soil would be sufficent
for this purpose. For the long term, all forms of rock covers can
provide good control of erosion and require little or no maintenance.
Vegetation can also be effective for stabilizing earthen covers.
When they can be established, shallow-rooted vegetative cover provides
the best protection to the earth cover. A number of shallow-rooted
plants native to the West and Southwest are available which will grow
in less than 3 feet of soil (BL82). This vegetation must be
periodically grazed or pruned to assure adequate growth for continued
stabilization. If not, the plants will mature and die. Most of these
plants are palatable to livestock, with excellent-to-good forage
value. However, shallow-rooted plants probably cannot survive the
droughts that frequently occur in the western and southwestern regions
of the United States without irrigation.
Frequent drought conditions favor the establishment of a
predominance of deep-rooted plants. Over time, the natural succession
of native local plants could be expected to replace introduced species
if maintenance is not performed (EP78f). Deep-rooted indigenous
vegetation may be able to survive on the tops and sides of the piles
and provide sufficiently good ground cover to stabilize the surface of
the pile. If the indigenous ground cover does not provide a cover
sufficently dense to protect the entire surface, a layer of rocky soil
will provide a rock cover in places where the vegetation fails.
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Vegetation should be irrigated and fertilized to provide the best
protection. One control method discussed in Chapter 6 and Appendix B
uses this means of controlling erosion of earth covers and specifies
continuing maintenance and irrigation to maintain the vegetation.
Flood Protection
Piles can be protected against floods by constructing barriers
designed to withstand floods, or by moving the piles to new sites.
Barriers are made by: (1) grading the piles so that the sides of the
piles have gradual slopes and providing protective rock on the slopes
(and on the top if needed), and (2) constructing embankments or dikes
on the sides of the piles and protecting exposed sides of the
embankments with riprap. Where the vulnerability to floods is great
enough, the piles can be moved to less vulnerable sites.
5.2.2 Preventing Radon Emissions
Radon emissions to the atmosphere from tailings piles can be
controlled by covering them with an impermeable barrier, like plastic,
or by covering the with enough semipermeable material, like earth, to
slow the passage of radon and increase the amount of radioactive decay
that takes place within the cover. Generally, the more permeable the
cover material and the lower the moisture content, the thicker it must
be to reduce radon emissions.
Natural cover materials are earth, clay, gravel, or a combination
of these. Clay, especially when moist, is generally more resistant to
the passage of radon than an equal thickness of earth or sand. Figure
5-1 shows curves for the percentage of radon which would penetrate
various thicknesses of different cover materials (FB76-78). The
half-value layer (HVL) is defined as that thickness of material which
reduces radon emissions to one-half its initial value. HVLs at actual
sites depend on earth composition, compaction, moisture content, and
other factors which vary from site to site with time. About 7 HVLs of
cover reduce radon emission to less than 1 percent of the uncovered
rate, and about 10 HVLs reduce the release to less than 0.1 percent.
Reductions are multiplicative; for example, 1 HVL of earth plus 1 HVL
of clay reduces radon emissions to 25 percent of the uncovered value
(i.e., 50 percent x 50 percent = 25 percent).
Figure 5-1 is a simplified description of radon retention
presented for illustrative purposes only. Appendix P of the NRC GEIS
(NRC80) contains a more complete discussion. Momeni et al. (Mob79)
have measured radon emissions from two tailings plots that had been
experimentally covered with increasing thicknesses of earth. The
results were in good agreement with calculations based on the
predictive methodology described in (NRC80) and (Mob79), at least over
the ten- to twenty-fold emission reduction range c-overed by the
experiment.
73
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100
P4
g
8
2
O
A = SANDY SOIL (HVL = 1.0 m)
B = SOIL (HVL = 0.5 m)
C = COMPACTED, MOIST SOIL
(HVL = 0.3 m)
D = CLAY (HVL = 0.12 m)
2345
COVER THICKNESS (METERS)
FIGURE 5-1. PERCENTAGE OF RADON PENETRATION
OF VARIOUS COVERS BY THICKNESS
74
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5-2.3 Controlling Direct Gamma Radiation
Covering tailings piles to stabilize them will also reduce direct
gamma radiation. Attenuation of gamma radiation depends on the
thickness of the cover. In Figure 5-2 we show how packed earth reduces
the primary gamma radiation for an extended source (Jab68) assuming an
alternation coefficient of 0.693 m~l (Sca74). This reduction of
gamma radiation is roughly approximated by a half-value layer of 0.04 m.
The actual reduction of gamma radiation from a tailings pile is
much more complicated. Gamma rays from the radon decay products are
distributed over a wide energy range. Primary radiation would be
supplemented by scattered radiation of lower energy. There are further
complicating factors such as the extent to which radon diffuses through
the cover before emitting gamma radiation thereby decreasing the
shielding thickness; this depends on the degree of earth compaction,
moisture content, type of earth, and other parameters.
If all of these corrections were applied, it would not drastically
alter Figure 5-2. A detailed analysis would still support the
following conclusions: a thin, impermeable cover, such as a plastic
sheet, will not reduce gamma radiation; earth thick enough to sustain
vegetation will significantly reduce gamma radiation; and earth or
other materials thick enough to reduce radon emissions will reduce
gamma radiation to insignificant levels.
5.2.4 Protecting Groundwater Quality
Groundwater contamination is caused by direct contact of
groundwater with tailings resulting in leaching of radioactive and
nonradioactive contaminants. There are several approaches that can be
used to protect groundwater. First, the tailings can be placed far
enough above the water table to avoid contact. Second, an impermeable
barrier can be imposed between the tailings and the groundwater,
provided that rain water does not percolate down and seep over the
barrier. In some cases, to make these controls feasible and long
lasting, the pile may have to be moved to a new site, or an
infiltration gallery constructed.
Virtually all tailings piles are in areas where evapotranspiration
exceeds rainfall. Therefore, rain water does not percolate through the
piles and contribute to additional contamination of groundwater.
However, water supplies could become contaminated in the near or
distant future by toxic materials that are already in the ground due to
operations that took place when the mill and tailings pile were
active.
These substances may be migrating to an aquifer, but they are
expected to move slowly. Groundwater itself often moves less than a
few feet per year, and only in coarse or cracked materials does it
exceed 1 mile per year. For these reasons, pollutants released from
tailings into the earth around the pile may not affect the quality of
nearby water supplies for decades or longer. Once polluted, the
75
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100
* An attenuation coefficient of 0.693 nT*
for an extended source of radon decay products
gives an approximate HVL of 0.04 m.
0.05 0.10 0.15 0.20
COVER THICKNESS (METERS)
0.25
0.30
FIGURE 5-2. REDUCTION OF GAMMA RADIATION
BY PACKED EARTH COVER (HVL* *w 0.04 m)
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quality of such water supplies cannot be quickly restored by
eliminating the source of pollutants.
Recent reports prepared for EPA (JA80, AW78) review methods that
can sometimes improve the quality of an already contaminated aquifer.
Other reports for EPA (SE80, MC80, GM78) present case studies of toxic
waste sites that have polluted groundwater and review remedial actions
for them. A group at the University of Idaho has reviewed water
pollution problems associated with six active uranium mills (UI80).
From such studies, it is clear that feasible remedial actions are very
site-specific. The economic and technical practicality of achieving
any preset degree of cleanup is uncertain. The only generally-
applicable control measure is to monitor the quality of the aquifer and
limit the use of its water. The length of time this may be necessary
would depend on the degree of contamination, the rate of groundwater
movement, the amount of dilution and dispersion taking place, and the
intended use of the water.
5.2.5 Assuring Long-Term Control
The ultimate objective of a tailings disposal program is not only
to reduce the potential hazards to an acceptable level now, but also to
provide this control for the anticipated life of the hazard.
Unfortunately, because of the long lifetimes of the radioactive
contaminants (thorium-230 has a half-life of about 80,000 years) and
the presence of other toxic chemicals (which never decay), the
potential that tailings have for harming people and the environment
will persist indefinitely (see Figure 3-2).
In this section we examine the technical and social factors that
influence the permanence of measures for controlling tailings.
Maintaining the integrity of thin impermeable covers over periods even
as short as tens to hundreds of years is highly uncertain under the
chemical and physical stresses that are likely to occur. We do not
consider them as a means of ensuring long-term control against erosion,
radon emission, misuse, and other hazards due to tailings.
Effects of Long-Term Erosion
Earthen covers will withstand erosion caused by rain and surface
water for long periods of time, but it is difficult to estimate how
long this will be. Some values for overall earth erosion rates in the
United States are given in Table 5-1. These erosion rates are average
and do not mean that all surfaces are eroded uniformly by this amount.
Widely varying rates of erosion, and also of deposition, can be found
within any drainage basin. Water erosion in the Colorado River
drainage basin is believed to range from 0.09 to 0.25 meters per 1000
years, based on several studies (Table 5-1). These rates can
reasonably be applied to the inactive mill tailings sites. This range
is probably applicable to controlling tailings below grade level. We
assume that the upper end of the range is probably applicable to
controlling tailings above grade level where vegetation and rock covers
are used.
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TABLE 5-1. SOIL EROSION RATES IN THE UNITED STATES
Erosion Rate Measurement Comments Reference
(cm/1,000 years) Technique
6 River load* Average for U.S. Ju64
4 River load
17 River load
5 River load
9 River load
5 Radioactive
dating
25 River load
5 River load
3 River load
Columbia River
Colorado River
Mississippi River
Colorado River
Amount of erosion of
volcanic extrusion in
southern Utah
Colorado River
Average for U.S.
Average for North
American continent
Ju64
Ju64
Haa75
Haa75
Haa75
Yo75
Da76
Pr74
*River load refers to erosion rate estimates based on the sediment
load (dissolved and detrital particles) carried by rivers.
78
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Rapid erosion rates are to be expected if vegetation and rock
covers are not used, or if their integrity is not maintained. For
example, erosion on some steep shale slopes (20° to 40°) in
Arizona averages 600 cm per 1000 years; even for slopes if less than
10°, the rate is 250 cm per 1000 years (Gib68). It is also noted
that the maximum rate of erosion occurs in areas with about 10 inches
(25 cm) of rainfall per year (Lac58) which is typical of the uranium
mining and milling areas in the western United States.
Wind erosion will be insignificant when a pile is protected from
water erosion by rock or vegetative cover. However, in dry areas
with bare earth covers, wind erosion could be severe. We conclude
that earthen covers several meters thick, stabilized with vegetation
or rock, should provide adequate protection against erosion for
several thousand years, unless a site is susceptible to catastrophic
damage from severe flooding or severe gully erosion (with no pro-
vision for short-term corrective action).
Effects of Natural Forces
Natural forces such as floods, heavy rains, windstorms,
tornados, earthquakes, and glaciers, may disrupt attempts to
stabilize tailings (EPA78b, GS78, Lu78, LabSO). These forces are
numerous and sometimes interrelated; some are so powerful we have
little chance of providing protection against them. We believe that
stability against natural forces can be provided for a few hundred to
a few thousand years by designing protective measures on a
case-by-case basis and taking site-specific factors into account.
Predictions of stability become less certain as the time period
increases. Beyond several thousand years, long-term geological
processes and climatic change will determine the effectiveness of
most "permanent" control methods. Glaciation, volcanism, uplifting
and denuding of the earth's surface, or deposition of material have
occurred in the western United States as recently as 10,000 years ago
and are likely to occur in the future.
Nelson and Shepherd (Ne78). have considered the impact on covers
by natural phenomena, including floods, windstorms, tornadoes,
earthquakes, and glaciers. These events could disperse the tailings,
making possible chronic exposure to their radioactive and
nonradioactive toxic constituents. The following comments are
summarized from their report.
Flooding, resulting from large rainstorms, rapidly melting snow,
or local cloudbursts, can disperse tailings over large areas in a
very short time. Also, increased earth moisture from flooding may
make steep slopes unstable, leading to landslides and eventual loss
of cover and disposal of tailings.
The size of floods to be designed for can be determined from
historical stream flow data and techniques of geomorphology. There
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is, however, always a chance that an actual flood will exceed the
designed maximum flood. Also, with changes in climate, the frequency
and size of floods.may change. Pluvial conditions in the Pleistocene
era (1 million to 10,000 years ago) resulted in abundant rainfall and
freshwater lakes in the western United States that were as large as
the contemporary Great Lakes.
Flood protection design must be based on very infrequent but
high-magnitude floods.(D These floods typically depart
significantly from the trend of more frequently observed floods and
will influence the design of protective measures. Where historical
records are of short duration compared to the required longevity of
the protection measures, prediction of extreme floods must rely on
techniques of geomorphology (Cob78). Once the size of flood event to
be used has been determined, flood protection can be incorporated
into the design of remedial measures.
Another measure of flood severity that is sometimes used as a
design criterion is the Standard Project Flood (SPF), which results
from the most severe combination of weather and hydrologic conditions
that are reasonably characteristic of the region involved, excluding
extremely rare combinations.
The "design flood" is the flood adopted as the basis for flood
protection for a facility after considering both hydrologic and
economic factors. In most areas, the characteristics of relatively
frequent floods, such as the 50-year flood, have been well
established, and engineers routinely design facilities protected from
such events. Where the failure of flood protection systems could
result in loss of lives and great property damage, however, a design
based on the maximum probable flood (MPF) may be justified. The
standard project flood (SPF) is often considered an appropriate
design basis for facilities where some risk would be tolerable, and
the added cost of providing greater protection would be significant.
'!' It is customary to rank the severity of floods in terms of the
average time over which floods of a given size or greater may be
expected to recur. For example, there will be an average of 5 floods
in 1,000 years that reach or exceed the "200-year Iflood". The
"maximum probable flood" (MPF), on the other hand, is the largest
flood that one would expect to occur in a given region for that
climate era. Geomorphic data are best for determining the past rate
of occurrence of very large floods. When such data are unavailable
the MPF can be estimated from historical records, but such estimates
are frequently shown to be inadequate when new severe rainstorms
occur.
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Sometimes the differences between various classes of floods are
not great. For example, the difference in height between the 100-year
flood and the SPF at the Grand Junction and Durango tailings piles have
been reported as 1 and 4 feet, respectively (FB76-78). The differences
in water velocity can be significant, however, and adequate protective
systems must be considered for the specific site.
Uncertainties in design specifications and performance may affect
the practicality of long-term flood protection systems. The
characteristics of long-term recurrence floods, such as the 1000-year
flood, are usually much less certain than those frequently occurring
during historical periods. Furthermore, because of potential damage
from erosion and earthquakes, our confidence in the ability of
conventional flood protection systems, such as dikes and stone
reinforcements, to withstand a flood declines with time into the
future. In view of these combined uncertainties, very conservatively
designed systems would be required to satisfy long-term flood
protection requirements. Whether for technical or economic reasons, if
those requirements could not be satisfied at the present location of a
tailings pile, it would have to be moved to a new site where long-term
floods are a more manageable threat.
The frequency and intensity of windstorms and tornadoes are
historically predictable. With a suitable cover or cap on the tailings
and protection of the surface against wind erosion, winds and tornadoes
should have little effect.
Earthquakes can damage caps and covers, as well as disrupt
barriers under disposal sites. The number and magnitude of past
earthquakes in an area is suggestive of the probability of earthquakes
in the future. As with any natural phenomenon, confidence in such
predictions rises as the reliability of earthquake and faulting
information increases. The likelihood that controls will fail because
of an earthquake depends on the chance of an earthquake of greater
intensity than controls were designed to withstand. Even if a plan is
designed on the basis of the maximum credible earthquake, there is
always the chance of an even larger earthquake. If an earthquake
occurs at a site, the likelihood that controls may partially fail will
generally be high. The quantity of tailings released, however, may be
small.
Glaciers occur in mountain valleys and as extensive (continental)
ice sheets, as in Greenland. Because of the magnitude of the forces
associated with glaciation, no portion of a surface depository would be
likely to survive even a small, relatively short-term glacier. The
likelihood of continental glaciation in the Western United States, even
far into the future, is remote. No evidence exists of continental
glaciation south or west of the Missouri River. Increased valley
glaciation in the west is a possibility, however. Several glaciers
exist high in the Rocky Mountains, and heavy glacial activity existed
in the mountains as recently as 10,000 years ago. An increase in
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valley glaciation is likely over the long term. Previously glaciated
mountain valleys are less desirable as tailings control sites than
nonglaciated sites, such as flat terrain or valleys created entirely by
erosion. The possibility of valley glaciation should be considered in
choosing between surface or below-ground disposal methods.
Effects of Human Activity
People may disrupt any measures undertaken to isolate tailings.
The NRC has discussed this problem (in Chapter 9 of their PGEIS
(NRC80)), as a justification for land use controls. Construction on
top of a disposal site, excavating or drilling, or using the surface
land for grazing and tilling, could disrupt controls or accelerate
natural erosion processes. It has been suggested that a disposal site
should not be made more attractive to human or animal habitation than
the surrounding environs, and perhaps that it should be made even less
attractive (Sh78).
The Act requires that uranium tailings control sites for residual
radioactive material be owned by an agency of the Federal Government
and licensed by the NRC (42 USC 7901). Such Federal responsibility
should provide control of any human activity which might disrupt the
isolation of the tailings for as long as that responsibility is
exercised. From a historical perspective, however, we should not
expect institutions to perform such functions for more than several
centuries (Ro77, Sca77, EPA78a, Bi78, Lu78). In its proposed criteria
for the management of radioactive wastes (EPA78d), EPA has suggested
that one should not plan to rely on institutional controls for more
than 100 years. During the period .of effective institutional control,
it should be possible to detect and remedy defects due to wind or water
erosion. This should provide some assurance of continued stability
against natural forces for a longer period of time.
Selecting remote or deep underground locations, to isolate
tailings from expected habitation and land-use patterns, is one way to
protect against degradation and intrusion by human activity after
institutional controls have become ineffective. Another which does not
require moving tailings is a thick earth cover with effective surface
stabilization.
5.2.6 Advanced Methods of Controlling Tailings
Uranium mills have generally been located near the mines where ore
is obtained, and often other mines are nearby. Placing tailings in
these mines is one obvious control method. The thick cover and erosion
protection implied by mine storage would prevent misuse and almost
completely control radon emissions for a substantially longer period
than could generally be expected from above-grade control methods.
However, since mines are usualfy below the water table, elaborate and
costly groundwater protection methods might be needed, and it is not
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clear that effective methods are available. Trans- portation hazards
and other costs also may be high. A major difficulty is that using
mines for tailings disposal makes future development of the mine's
residual resources impossible.
Nitric acid leaching to remove radium-226 and thorium-230 from the
tailings is a potential pretreatment technique. The technology has not
been fully developed but appears to be technically feasible. It is
attractive because about 90 percent of the radium and thorium can be
concentrated in a much smaller volume and the hazard of the tailings
greatly reduced. Major difficulties are the nonremoval of toxic
chemicals and high costs. Therefore, further remedial actions on the
tailings would still be required, and the volume of the tailings would
not be significantly reduced. There seems to be no incentive for using
this technique.
The use of caliche-type cover material for mill tailings piles has
been suggested (Br81) since this material may be effective in
preventing excessive mobilization of certain radionuclides and toxic
elements. However, the effectiveness and long-term performance of such
covers are not yet known.
Another recently investigated method is the sintering of tailings
to reduce the amount of radon emanating from the individual tailings
particles (DrSla, Thb81). This is attractive since it would greatly
reduce risks if the tailings are misused as fill material around
buildings. More evaluation of this method is needed (especially costs)
before we can decide if it is practical.
Advanced methods for controlling uranium mill tailings are
discussed further in Section B.6 of Appendix B.
5.3 Remedial Measures for Buildings
The only remedial measure that permanently eliminates the hazards
due to contaminated buildings is to remove all tailings from under and
around buildings and to dispose of them. Because this does not require
continued attention of the occupant to maintain its effectiveness, we
call this a "passive" control. The cost and complexity of removing
tailings from buildings depends on the amount and location of
tailings. For example, tailings used as backfill around the outside of
a foundation can be removed easily at relatively low cost. Removing
tailings from under a floor or foundation involves breaking up concrete
to reach the tailings, a costlier and more complex procedure. For some
buildings the cost of removing the tailings can exceed the value of the
structure.
Air cleaning, improving ventilation, or sealing the pathways
through which radon migrates indoors from tailings are active controls
that are effective but they are not permanent and require maintenance.
Air cleaning systems using standard electronic air filters have
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achieved a factor of ten reduction in radon decay product levels in
test houses (Wi78) and in experimental rooms (Ru81). Electronic air
cleaners do not remove radon from the air but do remove decay products
with about an 80 percent efficiency. To attain a factor of 10
reduction in radon decay product levels, about 5 house-volumes of
indoor air per hour must be circulated through the electronic air
filter, requiring a few hundred watts of electricity for fan power.
Circulation through an efficient filter can provide reductions in radon
decay product levels (Ru81) similar to electronic air cleaners, but
increased fan power is required.
Doubling ventilation rates will typically reduce radon levels in
half and decay product levels somewhat more. Even larger increase in
ventilation will reduce radon and radon decay products levels
proportionately. With windows and doors closed, the ventilation rate
in the average house is between 0.5 and 1 air changes per hour.
Opening several windows and doors will increase the house ventilation
rate several-fold. Comparable increases in ventilation can also be
achieved by forced ventilation supplied by exhaust fans and whole-house
fans.
Increased ventilation is a practical control measure during
temperate seasons when heating and cooling systems are not in use; at
other times, the cost of energy to heat or cool a few house-volumes of
air per hour is prohibitive. At such times of year selective
ventilation of unheated basements and crawl spaces may still be
practical. Some forced ventilation of the living space may also be
practical if air-to-air heat exchangers are used to recapture heat from
the exhausted air. Such devices can recycle up to 70 percent of the
energy which would otherwise be wasted.
Identifying and sealing pathways of radon entry does not require
the operation of equipment, but the long-term effectiveness of sealants
is not known. Therefore, we assume periodic inspection and repair will
be needed. Common routes of entry are cracks in the foundation slab
and walls, gaps in utility penetrations of the foundation, and channels
inside hollow concrete blocks which often are used for foundation
walls. Cracks and gaps can be caulked to prevent radon entry.
Pathways in hollow blocks can be eliminated somewhat less successfully
by filling the block walls with grout. These and similar measures have
been used with some success in both Elliot Lake, Ontario (DS80), and in
the phosphate region of central Flordia (DS81).
In summation, removal of tailings is the only permanent remedial
measure and generally is the most effective. However, where indoor
gamma exposures are not high, active controls can be equally effective
or, in some cases, more effective at much lower cost. This is
especially true when radon decay product levels are within a few
standard deviations above normal average indoor levels. Active
measures do not reduce gamma radiation, however.
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5.4 Remedial Measures for Contaminated Lands and Offsite Properties
The methods of land cleanup are somewhat different for land near
piles compared to offsite properties, so we will cover them
separately. The tailings near piles have usually been transported by
wind and water erosion, while the distant tailings have been
transported by people for use as fill, soil additives, and other
purposes.
5.4.1 Land Near the Tailings Pile
There are two distinct control measures: disposal and limitation
of access. The first requires removal of all contaminated soil and
disposal of it along with the rest of the pile. For most sites this
involves scraping off the first few inches (occasionally feet) (Ha80,
Fo76-78) of earth from several dozen acres around the pile. Removal of
deeper contamination, from water erosion and leaching will require
additional heavy equipment such as backhoes, scrapers, and tractors.
This will generally involve a much smaller area than for windblown
contamination. The use of earthmoving equipment to clean up a tailings
site is documented in a recent report (HabSO).
The second control measure is to limit access to and use of
contaminated areas. This must include stabilization of the surface to
prevent further spreading of contamination, the construction and
maintenance of fences, a monitoring program to monitor and prevent the
spread of contamination, and withdrawal of land from productive use for
an indefinite period of time.
5.4.2 Land Distant from the Tailings Pile
For offsite properties distant from the pile, where tailings have
been misused (over 6500 have been identified), the only feasible
control measure is to remove the tailings (with hand tools or
earthmoving machinery) from the properties and transport them back to
the tailings piles or other approved control areas. Some of these
properties clearly pose a present or potential hazard. One example
would be a highly contaminated property where people spend a large
amount of time, or which potentially could be a site for a new building
or an addition to an existing building. In other places, offsite
contamination causes no significant present or potential hazard.
Examples are tailings under public sidewalks or used as fill around
sewer lines.
The recovery of tailings (used in the construction of sidewalks,
driveways and sewer lines, for example) is often costly and may require
destruction and reconstruction actions. Topsoil may have to be used to
replace tailings that have been used in gardens and yards. Vegetation
may need to be replaced after tailings are removed.
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Chapter 6: COSTS AND BENEFITS OF ALTERNATIVE
STANDARDS FOR CONTROL OF TAILINGS PILES
6.1 Alternative Standards for Control of Tailings Piles
We have investigated six alternatives for standards to control
tailings piles (one is EPA's proposed standard of January 9, 1981
(46 FR 2556)). Each is analyzed in terms of representative control
methods that should reduce to the desired level the radiological and
toxic chemical hazards from tailings piles and from tailings deposited
on contiguous property. The methods, as well as their costs and
effectiveness, vary over wide ranges.
Three basic philosophical approaches are taken in the development
of alternative standards:
1. Provide minimum acceptable health protection and rely
primarily on institutional controls, incurring the
least cost.
2. Rely on optimizing benefits versus costs and provide longer
term health protection without using institutional controls.
The costs for this optimized cost-benefit approach would be
somewhat higher.
3. Provide the best control reasonably achievable and prevent any
degradation of the environment. Costs are substantially
higher.
The Proposed Standard and Standard A are best characterized as
nondegradation alternatives; B and C are optimized cost-benefit
alternatives; D and E are least-cost alternatives.
All of the standards have three principal objectives:
1. To prevent erosion and misuse of tailings for long periods
of time.
2. To limit radon emissions from the surface of the pile.
3. To control the amount of degradation of water quality.
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TABLE 6-1. ALTERNATIVE STANDARDS FOR CONTROL OF URANIUM MILL TAILINGS
Principal Requirements
Alternative
Minimum Time That
Controls Should
Prevent Erosion
and Misuse (years)
For Radon
Emissions from
Top of Pile
(pCi/m2s)
For Water Quality
Protection
No standards
EPA
Proposed
Standard
None (radioactivity
decays to 10%
in 265,000 years)
1,000
Alternative A 1,000-10,000
Alternative B
200-1,000
Alternative C Indefinite, long-term
Alternative D
Durable cover;
100-year institutional
control; discourage
moving of piles
Alternative E
Minimal cover to prevent
windblown erosion only;
100- to 200-year institu-
tional control; move only
piles in immediate danger
due to floods
No limit
(The average
emission is
500 pCi/m2s)
2 above
background
2 above
background
20
100
No
requirement
No
requirement
None (Toxic
chemicals in
tailings at
concentrations
100 times
background)
No increased
concentration
of toxic chemicals
No degradation
that would prevent
present uses
Guidance, based
on water quality
criteria
Guidance, based
on water quality
criteria
Prevent
significant
erosion of
tailings to
surface water or
groundwater, or
treat water before
use.
No protection
required
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In Table 6-1, we show, for each alternative, the requirements
selected to meet these objectives. Most of the requirements are
expressed quantitatively, and in combination they achieve the overall
objective of reducing risks to people from tailings.
The entry entitled "No standards" in Table 6-1 represents the
present situation, the conditions to be expected if nothing is done
(see Chapter 3). The piles will remain hazardous for a long time,
taking about 265,000 years for the radioactivity to decay to 10 percent
of present levels. The radon emission rate from an average pile is
approximately 500 pCi/m^s, compared to the background rate for
typical soil surfaces of 0.2 to about 1.8 pCi/m^s. While we have
little indication that degradation in water quality has already taken
place, we do know the concentration of some toxic chemicals in the
tailings to be hundreds of times the background levels in ordinary
soils, so that the potential for contaminating water is present and
continues indefinitely.
The Proposed Standard. The Proposed Standard specified that
control measures should limit radon emissions and water pollution for
at least 1,000 years. Thus, controls are designed so there is
reasonable expectation that the measures undertaken to stabilize the
piles and to prevent any degradation of water quality will remain
effective for at least that long. The proposed radon emission limit is
2 pCi/m^s (above background).
Alternative A. Control measures are designed to be effective for
1,000 to 10,000 years, "the radon emission limit is 2 pCi/m^s above
background and the quality of water is to be maintained so that present
usage can continue. For water quality, this is less stringent than the
requirement in the proposed standard, since water quality can be
degraded, but not to the point at which contamination levels would be
inconsistent with the present uses of the water.
Alternative B. In this alternative, the longevity requirement is
reduced to 200 to 1,000 years. The radon emission limit is increased
to 20 pCi/m^s. Measures are recommended to help assure that
applicable water quality criteria are met.
Alternative C. The number of years over which the integrity of
control measures shall be designed to be maintained is not specified,
but controls should remain effective for an "indefinite time." The
radon emission limit is increased to 100 pCi/m^s. Measures are
recommended to help assure that applicable water quality criteria are
met.
Alternative D. This alternative consists of qualitative
requirements. A durable cover is specified to be applied to the piles,
so that only reasonable maintenance is needed to maintain the cover for
100 years. Moving the piles is specifically discouraged. No radon
emission limit is specified. Erosion that leads to contamination of
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surface or ground water must be prevented, or contaminated water must be
treated before it is used, whichever costs less.
Alternative E. This alternative requires sufficient cover to
control windblown erosion only, with the integrity maintained for a
period of 100 to 200 years. Radon control is not required, and there is
no protection required for surface water or ground water-
6.2 Control Methods Selected for Each Alternative Standard
Our purpose is to estimate the cost and benefits of each standard.
Though we make every effort to provide realistic estimates, we are most
concerned about the accuracy of relative costs and benefits. Therefore,
all assumptions were applied consistently to the various control methods
chosen.
In this section a specific combination of control methods is chosen
to meet the requirements for each of the alternative standards (Table
6-1). Numerous combinations of control methods (which we discussed in
Chapter 5) could be devised for satisfying each alternative standard, so
we have attempted to pick least-cost options relying on standard
construction methods. A detailed explanation of how these costs were
estimated is presented in Appendix B.
The length of time that control measures must maintain their
integrity determines how they are engineered. As we increase the time we
want the controls to last, control measures tend to become more massive
and expensive. The following are examples: For longer protection
against floods and erosion, piles can be designed with more gradually
sloped sides; but this requires additional grading and more earth cover.
Dikes can be added to give long-term stability against floods. For
greater resistance to erosion and floods, earth covers can be made
thicker and an additional rock cover can be added. Large rock can be
used rather than small rock to provide better protection against
weathering and the pressure of floods. (Large rock is also less likely
to be stolen).
The control methods selected for each alternative standard are
summarized in Table 6-2. The cover materials are clay, earth, and rock,
which are widely available and have low unit costs compared to processed
materials such as cement, asphalt, and plastic compounds. Flood
protection is provided through embankments or dikes, with riprap on sides
that are vulnerable to floods.
Under the most protective alternative (A), we estimate that as many
as 12 piles may have to be moved; 9 because of the likelihood of flooding
and an additional 3 because of their proximity to population centers (see
Chapter 3). If a pile is moved, it is assumed that the new site will not
be vulnerable to flooding and, thus, no embankments will be needed for
flood protection, but vegetation and rock covers are provided to resist
erosion. No ground water protection measures are provided, because we
assume that the selected new sites avoid this hazard.
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TABLE 6-2. CONTROL METHODS SELECTED FOR EACH ALTERNATIVE STANDARD
vo
Alternative
EPA Proposed
Standard
Alternative
A
Alternative
B
Alternative
C
Alternative
D
Alternative
E
Stabilization:
Maximum Slope
of cover
(Horizontal: Vertical)
5:1
8:1
(Most stable)
4:1
5:1
3:1
3:1
(Least stable)
Stabilization:
Thickness of Cover
(Clay) (Earth)
(m) (m)
0.6 3
0.6 3
None 3
None 1
None 0.5
None 0.5
Add Rock
Thickness
Sides
(m)
0.33
0.5
0.33
0.33
0.15
None
Control
Cover:
of Cover
Top
(m)
None
0.15
None
0.15
0.15
None
Methods
Add Maintain Provide Flood Move the
Vegetative Access Con- Control Measures Pile
Cover trol and Re- (Number of (Number of
pair Cover Sites) Piles)
Top No 0 9
None No 0 12
Top No 6 3
None Yes
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EPA Proposed Standard. The sides of the piles would be contoured
to a 5:1 slope. The tailings piles are to be covered with 0.6 meters
of clay and 3 meters of earth, and the earth on the slopes would be
stabilized with a cover of 0.33 meters of rock, with the top of the
pile planted with indigenous vegetation. The upper 0.33 meters of
earth on the tops of the piles should be a rocky soil that would
provide protection in case the vegetation fails. To prevent erosion by
floods, nine piles are to be moved; at the new sites, pits will be dug,
the tailings placed in the pits, and the excavated earth used to cover
the tailings.
Alternative A. The sides of the piles would be contoured to an
8:1 slope and the tailings piles are to be covered with 0.6 meters of
clay and 3 meters of earth. The earth on the slopes and the tops would
be stabilized with covers of 0.5 and 0.15 meters of rock, respectively.
To prevent spreading by floods, nine piles are moved. Three addi-
tional piles are moved because of proximity to people. At the new
sites, pits are to be dug, the tailings are to be placed in them, and
the excavated earth would be used to cover them.
Alternative B. In this option the tailings would be graded to a
4:1 slope, and the entire tailings piles would be covered with 3
meters of earth. The earth on the slopes would be covered with 0.33
meters of rock and the tops planted with local vegetation. Approxi-
mately the upper 0.33 meters of earth on the tops of the piles would
be a rocky soil to provide rock covers in case the vegetation fails.
Flood protection embankments are to be provided at six of the vul-
nerable sites. Ground water and flood protection is to be achieved
for the other three piles by moving them to new sites. For these
piles, pits are to be excavated at the new sites, tailings put into
the pits, and the excavated material used as covers.
Alternative C. The sides of the piles are to be contoured to a
5:1 slope and the entire tailings piles would be covered with 1 meter
of earth. The slopes are to be stabilized with 0.33 meters of rock;
the tops with 0.15 meters of rock. The number of piles requiring
flood protection would vary from one to six, depending on further
examination of the flooding risk and the number of piles to be moved.
The number of piles to be moved varies from three to eight, depending
on further evaluation of the risk of flooding. For piles that are to
be moved, earth would be excavated to serve as a cover material for
the disposed tailings. The disposal site would be fenced, and the
fence maintained for an indefinite period.
Alternative D. The sides of the tailings piles would be
contoured to a 3:1 slope and the entire piles covered with 0.5 meters
of earth. A 0.15-meter rock cover is to be placed on the tops and the
slopes. Special flood protection, using dikes or protective
embankments, would be provided at three sites. The tailings would be
moved from one site to provide flood protection. The disposal sites
would be fenced and maintained for 100 years.
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Alternative E. The sides of the tailings piles would be contoured
to a 3:1 slope and the piles covered with 0.5 meters of earth. The
tops and slopes of the pile are then to be covered with vegetation, and
an irrigation system installed to provide wind and water erosion
control. One pile would be moved to prevent spreading by floods. The
disposal sites are to be fenced and maintained for 100 to 200 years.
6.3 Costs of the Control Methods
Cost estimates were made by considering the control costs for two
model tailings piles, a "normal" pile representing the 17 larger
designated piles and a "small" pile representing the remaining 7 small
piles. These costs were then scaled to generate the cost for all piles
combined. We developed cost estimates for two sizes of piles because
of the disparity in the sizes of the piles covered by the remedial
action program. Details of the unit costs and other assumptions are in
Appendix B.
The costs of in-place control and for moving and control at a new
site, for both the normal pile and the small pile, are shown in Table
6-3 (from Tables B-2 and B-3 in Appendix B.) These costs do not
include overhead or contingencies.
The costs for each control method, estimated for all the
designated sites, are shown in Table 6-4. These costs are derived from
Table B-4 in Appendix B; they include a 50-percent allowance for the
costs of engineering, overhead, profit, and contingencies. The final
total also includes DOE's estimated cost for overhead to administer the
entire program. DOE does not expect this overhead to vary signifi-
cantly for any of the alternatives considered.
6.4 Risk of Accidents When Carrying Out Control Methods
One of the costs of control is the possibility of accidental
deaths during the installation of control methods and when moving
tailings. Table 6-5 shows our estimate of the number of accidental
deaths that could be associated with each tailings alternative
standard. In general, more than half of the deaths are occupationally
related—accidental deaths of workers and premature, radiation-induced
deaths of construction workers at the tailings sites. The balance are,
for the most part, accidental deaths to members of the public occurring
while tailings are being transported.
There are two important parameters in this simplified analysis of
the number of occupational and accidental deaths associated with
controlling tailings. The first is the number of person-hours of labor
required to do the job. This was used to estimate the number of
construction-related deaths, as well as the number of premature deaths
from radiation exposure. The second is the number of truck-miles
traveled over public roads to move tailings to new sites or to bring
cover and other materials to the sites.
93
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TABLE 6-3. ESTIMATED 1981 COSTS OF CONTROL METHODS FOR TWO MODEL
Alternative
URANIUM MILL TAILINGS PILES
Control Onsite
(millions of dollars)
Normal Pile Small Pile
Move and Control
at New Site
(millions of dollars)
Normal Pile Small Pile
EPA Proposed 4.9
Standard
Alternative A 7.0
Alternative B 2.9
Alternative C 3.0
Alternative D 2.2
Alternative E 1.7
1.2
1.6
0.7
1.0
0.8
0.7
11.0
12.6
10.1
9.8
8.9
8.6
1.0
1.2
0.9
1.3
1.2
1.2
94
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Table 6-4. ESTIMATED 1981 COSTS FOR CONTROLLING URANIUM MILL TAILINGS
(in Million of Dollars)
Cost of Control Method
Alternative „.
Cleaning up
Sites
EPA Proposed
Standard 35
Alternative A 35
Alternative B 35
Alternative Cl^c^ 35
Alternative C2(c) 35
vo Alternative D 35
Ul
Alternative E 35
Controlling Adding
Piles Embankments
91 (0)
129 (0)
55 6 (6)
58 1 (1)
58 6 (6)
43 3 (3)
34 (0)
Overhead &
Moving,. , Subtotal Contigency
Piles Costs Costs
43. (9) 169 85
56 (12) 221 110
21 (3) 117 58
42 (8) 136 68
20 (3) 120 60
7 (1) 88 44
7 (1) 76 38
DOE
Overhead Total
Costs Costs
118 372
118 448
118 294
118 322
118 297
118 250
118 232
'a'Numbers in parentheses are the number of piles to which the control method applies.
(^'Portion of total cost that is attributable to moving piles to new disposal sites.
distinction between Alternatives Cl and C2 is in the number of piles moved rather than protected in place with embankments.
-------
The labor required for piles that are to be controlled onsite is
proportional to the amount of earthmoving to be done; a gradual slope
requires more earthmoving than a steep slope, roughly in proportion to
the ratio of the slopes, and a thick cover requires more earthmoving
than a thinner one. Based on figures from a DOE contractor (DeWSl), we
estimated that Alternatives D or E would require about 30 person-years
of labor for a large pile. If we adjust this for different slopes and
different cover thicknesses (assuming a 25-percent increase for each
additional meter of cover), the labor requirements for Alternatives C,
B, A, and the Proposed Standard are 60, 75, 150, and 100 person-years,
respectively. When a pile is to be moved, the labor requirements at
the disposal site are about the same as for Alternatives C, B, and A,
but there is an additional labor need of about 50 person-years at the
original tailings site.
The labor requirements to control all the piles under the various
alternatives are summarized in Table 6-5. The occupational deaths
resulting from this are estimated from mortality statistics for the
construction industry: 60 deaths per 100,000 worker-years (NS78).
This corresponds to 6 x 10~^ accidental deaths per person-year.
Radiation-induced deaths are difficult to estimate since it is
impossible to anticipate measures that might be used to protect
workers. However, in the worst case, the gamma radiation exposure rate
over a bare tailings pile (typically 1 mrem/h) for a working year would
lead to exposures of about 2 rem/y. Inhalation of radon decay products
would, at most, lead to a comparable risk. In Table 6-5, we have
assumed that the maximum risk of premature, radiation-induced death is
equivalent to the risk from an exposure of 4 rem (whole-body
equivalent) of gamma radiation per person-year of labor.
The transportation deaths in Table 6-5 were calculated by assuming
that, when a pile is moved, it is transported in 12-yd^ trucks to a
site 10 miles away. For a 1.1 million cubic-yard pile of tailings,
roughly 1.8 million truck-miles are logged. Using a figure of 0.7 x
10~' deaths per truck-mile among drivers and the public (DOESOa), we
estimated 0.13 deaths for each pile moved. We have not estimated
deaths from the transport of cover materials, since most of these
materials will be obtained close to the disposal site and, therefore,
do not entail a great deal of travel over public roads. Their bulk
volume is also small compared to the volume of a tailings pile.
6.5 Advanced Control Methods
There are other control methods in addition to those considered
here. One is the use of a soil cement cap over the tailings. The soil
cement is made from the tailings. We have analyzed the costs and
benefits of a 6-inch soil cement cap over the sides and top of the
piles with a 1 meter earthen cover protected by rock. The costs and
benefits of this method are about the same as those achieved by
Alternative B. This method is more fully discussed in Appendix B.
96
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TABIE 6-5. ESTIMATED ACCIDENTAL DEATHS ASSOCIATED WITH ALTERNATIVE STANDARDS
\o
Large Piles to be Moved
Alternative
EPA Proposed
Standard
Alternative A
Alternative B
Alternative C
Alternative D
Alternative E
Numb er
7
10
3
3
1
1
Labor
(per son -years)
2000
3000
1400
1200
600
600
Accidental Deaths
to Workers at
Tailings Sites
1.2
1.8
0.8
0.7
0.4
0.4
Radiation- Transportation
Induced Deaths Deaths
to Workers (Workers & Public)
0.6 0.9
0.9 1.3
0.4 0.4
0.3 0.4
0.2 0.13
0.2 0.13
Total
Deaths
2.7
4.0
1.6
1.4
0.7
0.7
-------
Other control methods were not included in the cost-benefit
analysis because of their high costs and our limited knowledge of their
long-term environmental impact. These methods are: nitric acid
leaching for the removal of hazardous material, burial in nearby strip
mines, burial in underground mines, and thermal stabilization. If
their costs were not prohibitive, nitric acid leaching and thermal
stabilization could significantly reduce the hazards from contaminants
in the tailings. In addition to the high costs of burying the tailings
in strip mines and underground mines, the tailings may contaminate
ground water. These control methods have been briefly described in
Chapter 5. Their costs are more fully discussed in Appendix B.
6.6 Benefits Associated with the Alternative Standards
The benefit we are best able to estimate is the number of adverse
health effects averted by radon control. We can estimate the reduction
in radon emissions resulting from the placement of earthen cover, and
we can translate radon emissions reduction into health effects averted
by using models for estimating the health effects from inhaling radon
(see Chapter 4). Therefore, the benefits of radon control are
quantifiable in number of adverse health effects averted and in
reduction in risk to persons residing closest to the piles.
Most of the other benefits from controlling the tailings piles are
not quantifiable, although the goal is well defined: the reduction of
health risks from exposure to the hazardous materials contained in the
tailings. For example, we are unable to translate flood protection
measures into the number of health effects averted. The missing
linkages are: (1) the translation from flood protection measures to
flood damage averted; (2) the translation from flood damage to
quantities of tailings spread along the downstream river valley; and
(3) the translation from the tailings spread along the river valley to
the number and degree of exposures. There are similar problems with
quantifying the chance and consequences of misuse and the permanence of
control, i.e. the years of erosional spreading avoided, and the years
of water quality protection, and the consequences avoided.
Our estimates of benefits for each alternative have been listed in
Table 6-6. Benefits are quantified when we are able to do so. The
benefits of each of the options are measured against the status quo;
that is, no remedial action on the tailings piles themselves and no
cleanup of the mill sites and mill buildings.
Benefits of Stabilization
We have characterized the benefits of stabilizing the tailings
piles in terms of the reduced chance of misuse, the permanence of
controls for inhibiting misuse, the years of erosional spreading
avoided, and the reduction in vulnerability to floods. The number of
health effects averted cannot Be estimated.
98
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TABLE 6-6. BENEFITS DERIVED FROM CONTROLLING URANIUM MILL TAILINGS PILES
Benefits of Stabilization
Chance Permanence of Control Against
Alternative
No standards
EPA Proposed
Standard
Alternative A
Alternative B
Alternative C
Alternative D
Alternative E
of Misuse Erosional Spreading
Misuse (years)
Most likely 0
Very
Unlikely >1000
(Thick
cover)
Very >1000
Unlikely
(Thick cover)
Very >1000
Unlikely
(Thick cover)
Unlikely 1000
(Medium
cover)
More 100
likely
(Thin cover)
More 100-200
likely
(Thin cover)
(years)
0
Many
thousands
Many
thousands
Many
thousands
Thousands
Hundreds
Few hundred
Benefits of
Benefits of Radon Control Protecting Water
Number of Sites Residual Risk Deaths
Vulnerable to of Lung Cancer In first
Avoided Surface Water
Protected
Flooding (% reduction) 100 years Total
9 3 in 102 0
(0)
0 1 in 104 200
(99.7)
0 1 in 104 200
(99.7)
0 1 in 103 190
(97)
0 6 in 103 150
(80)
5 1.5-3 in 102 100
(less than 50)
8 1.5-3 in 102 100
(less than 50)
0
Many
thousands
Many
thousands
Many
thousands
Thousands
800
600
(years)
0
Many
thousands
Many
thousands
Many
thousands
Thousands
Hundreds
Few
hundred
-------
The major benefit of stabilizing a pile is the prevention of the
hazards associated with human intrusion and misuse of the tailings
piles; this can be expressed only in qualitative terms. We have
estimated, as best we can, the number of years that control is
anticipated to inhibit misuse. This ranges from greater than 1,000
years for the Proposed Standard and Alternatives A and B, to 1,000
years for Alternative C, 100 to 200 years for Alternative E, and 100
years for Alternative D. The likelihood of misuse during the period of
effectiveness of these options ranges from "very unlikely" for the pro-
posed standard and Alternatives A and B to "more likely" for Alterna-
tives D and E.
The Grand Junction cleanup program is an example of the kind of
expensive remedial actions that stabilization should prevent. The
tailings in Grand Junction buildings are now being cleaned up at a cost
of about $23 million to avoid an estimated 75-150 lung cancer deaths.
The additional cost of cleaning up contaminated offsite land is
estimated at $22 to $31 million.
A second benefit of stabilization is the prevention of erosion.
Erosion of existing piles over the last 20 to 30 years has contaminated
about 4,000 acres of land which now cannot be used for most purposes.
Depending on the cleanup standards (see Chapter 7), this will cost
about $10 million to clean up (or $0.3 to $0.5 million per year of
erosion). If piles are not stablized, long-term erosion would
necessitate repeated cleanups or indefinite restrictions on land use.
Controls needed to prevent erosion are less strict than controls to
prevent misuse; therefore, erosion is usually controlled longer than
misuse for a given alternative.
The benefit of preventing tailings erosion can be expressed in a
semiquantitative way by estimating the number of years that erosional
spreading is prevented. Protection from erosion is estimated to range
from a few hundred years for Alternative E to many thousands of years
for the Proposed Standard and Alternatives A and B. Since erosion is
-now -taking place, benefits can 1>e derived from any remedial measure
that reduces erosion.
A third benefit of stabilization is to prevent floods from washing
tailings downstream to flood plains, where land use is residential and
agricultural. Should this happen, very expensive remedial measures
would probably be needed. A recent tailings "spill" (failure of a dam
containing a tailings pile at an active mill) in the Southwest
contaminated hundreds of acres of land (of limited value) over a
distance of about 20 miles. We estimate the cost of cleanup of that
spill to be $1 million to $5 million, depending on the cleanup criteria
used. The total radioactivity spilled was less than 5 percent of that
in an average inactive pile.
Although the benefits of having tailings piles resistant to flood
damage cannot be directly measured, we can estimate the number of piles
vulnerable to floods under each of the alternatives. Benefits of
100
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protection from flood damage are then quantified as the number of piles
that would be moved from a flood-prone area and the number of cases in
which dikes would be constructed around piles left in place. We
estimate that nine of the inactive sites are now vulnerable to long-
term floods. One tailings pile, on the side of a bluff overlooking a
river, is considered so vulnerable that it is to be moved under all
options. The number of sites moved to reduce their vulnerability to
floods is one for Alternatives D and E, three for Alternative B, three
to eight for Alternative C, and nine for the Proposed Standard and
Alternative A. Under Alternative E, none of the eight remaining sites
vulnerable to floods are diked; under Alternative D, three of those
sites are diked.
Benefits of JRadon ContrpJL
The estimated benefits of radon control can be quantified (under
certain assumptions, as described in Chapter 4). A total of 200 lung
cancer deaths from radon emissions from all tailings piles is estimated
to occur in each 100 years, continuing for many tens of thousands of
years, unless remedial actions are undertaken. Re- medial actions
taken under the Proposed Standard and Alternative A will avert
virtually all of these cancer deaths for many thousands of years, and
Alternative B provides about 96-percent protection for nearly the same
period of time. The number of deaths averted is less with the other
options, decreasing to approximately 100 for Alternatives D and E. The
total deaths averted in the future is estimated to be many thousands
for the Proposed Standard and Alternatives A and B but will be lower
for the other options, decreasing to approximately 600 for Alternative
E.
A second benefit of radon control is the reduction of risk to
nearby individuals. The maximum risk of death from radon emissions to
the persons living near the piles is estimated to be 1.5 to 3 chances
in 100 for Alternatives D and E, 6 in 1,000 for Alternative C, 1 in
1,000 for Alternative B, and 1 in 10,000 for the Proposed Standard and
Alternative A.
Benefits of Protect ing Water
Measures to safeguard water quality are of benefit because they
prevent toxic and radioactive contamination. We cannot quantify the
number of health effects averted, but we have attempted to estimate the
benefit of each option in terms of the number of years water will be
protected. EPA's Proposed Standard and Alternatives A and B should
provide thousands of years of protection. The least amount of
protection, a few hundred years, is provided by Alternative D.
6.7 Summary of Benefits and Costs
We have analyzed the benefits and costs of the control methods
that satisfy the basic objectives of six alternative standards. In
Tables 6-4, 6-5, and 6-6, we show that the least costly standards
provide the fewest benefits and that benefits increase with higher
costs. The following is a summary, beginning with the least
restrictive.
101
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Alternative E. The objective of this standard is to prevent wind
erosion for a period of 100 to 200 years. This would provide some
protection against erosion from water runoff, but there is no
protection from floods for eight of the nine piles believed to be
vulnerable. One tailings pile is to be moved because of its high
vulnerability to floods. This option provides no control of radon
emissions or protection of water quality.
This least protective control method uses thin covers of earth
held in place by vegetation that must be irrigated. Sites are to be
fenced. For an indefinite period this method relies on institutional
controls such as regular inspection and repair of the cover and fence,
operation and management of the irrigation system, and periodic
replacement of irrigation equipment.
The risk of lung cancer from inhalation of radon decay products is
1.5 to 3 in 100 for persons residing near the piles. An estimated 100
lung cancer deaths will be avoided in the first 100 years, and approxi-
mately 600 future deaths would be avoided in total.
The estimated cost is $232 million. We estimate that this
alternative will lead to one accidental death of a worker or of a
member of the public.
Alternative D. A thin earth cover and a minimum cover of rock
hold surfaces in place. One pile will be moved. Embankments or dikes
will protect the three other piles most vulnerable to floods. The rock
gives the cover some durability but is not thick enough to reduce the
likelihood of misuse. Misuse is prevented by institutional controls.
Periodic inspections and repairs of the fence and cover are required.
About 100 lung cancer deaths are avoided in the first 100 years, and
about 800 future deaths would be avoided. There is some control of
water quality. Measures to prevent erosion that might cause surface
water or ground water contamination or to treat contaminated water are
included.
The estimated cost of this alternative is $250 million. In
carrying out the operations required under this option, we estimate
that there would be one accidental death of a worker or of a member of
the public.
Alternative C. This alternative provides thick cover, gradual
slopes, and thick layers of rock on the slopes. The controls are
durable, and the resistance to misuse is great. Some form of flood
protection for all nine vulnerable sites would be provided by moving
three to eight sites (depending on site characteristics) and adding
embankments to the rest.
This alternative specifically limits radon emissions to 100
pCi/m^s. The maximum risk of lung cancer from radon to the nearest
resident is 6 in 1,000; 150 lung cancer deaths are averted in the first
102
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100 years, with thousands of deaths averted in the future.
Recommendations are made for adequate water protection.
These benefits would cost about $300 million. Between one and two
accidental deaths of workers or of members of the public are predicted
to occur in carrying out operations to put this alternative into effect.
Alternative B. Control methods under this alternative provide
thick earth covers but allow relatively steep slopes on the sides of
the piles. Thin rock covers on the slopes and vegetation on the tops
of the piles are to be used. No irrigation would be provided, so
vegetation must be indigenous. No fence is required, and no
institutional controls are necessary. This method provides good
resistance to misuse, good cover durability, and long-term erosion
control. Nine piles are protected from floods, three piles are to be
moved, and embankments are to be placed around the rest. Radon
emissions would be limited to 20 pCi/m^s above background. The risk
of lung cancer for the nearest residents is to 1 in 1,000. About 190
lung cancer deaths would be avoided in the first 100 years, and the
total future deaths averted are many thousands. Water quality
protection recommendations are made to provide adequate protection.
These benefits would cost about $290 million. Construction
activities for this alternative are expected to result in between one
and two accidental deaths of workers or of members the public.
Alternative A. The control method under this alternative uses
clay caps on the tops of the tailings protected by thick earth covers,
with relatively thick layers of rock over that. The maximum slopes are
gradual, misuse is very unlikely, and the cover should last thousands
of years. No fences are needed, therefore no institutional controls
are required. Twelve piles are to be moved; nine are to be moved for
protection from floods, three because they are close to population
centers. The clay caps provide almost complete radon control. The
radon emission limit is 2 pCi/m s. The risk of lung cancer to the
nearest resident is reduced to 1 in 10,000; The number of lung cancer
deaths averted in the first 100 years is 200. Many thousands of deaths
are averted in the future. This alternative provides strict water
pollution controls; no degradation in use is allowed.
This is a relatively high-cost alternative that allows virtually
no degradation of the environment. The cost is estimated to be about
$450 million. Under this alternative, we estimate that construction
activities will cause four accidental deaths of workers or members of
the public. It probably provides the best control achievable without
burying the piles below grade.
Proposed Standard. Thick stable long lasting covers are
provided. No fences or institutional controls are required. Nine
103
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piles vulnerable to floods would be moved but piles near population
centers would not. There are 200 lung cancer deaths avoided in the
first 100 years; many thousands are avoided in the future. No
increased concentration of contaminants in surface and ground water is
allowed.
The Proposed Standard Alternative is a high-cost alternative, with
a cost of £}370 million. There should be virtually no degradation of
the environment. Construction activities are expected to cause three
accidental deaths of workers or of members of the public.
104
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Chapter 7: COSTS AND BENEFITS OF CLEANUP STANDARDS
FOR BUILDINGS AND LAND CONTAMINATED WITH TAILINGS
In this chapter we discuss the costs and benefits of cleanup
standards for buildings and land. Near-site contaminated lands and
more distant offsite contaminated properties present different
problems, and we consider them separately.
7.1 Cleanup Standards for Buildings
We have analyzed four cleanup standards for buildings with the
objective of reducing indoor radon decay product concentrations and
gamma radiation levels caused by tailings. All four standards reflect
some balancing of costs and benefits.
High-cost standards that prevent any degradation of the
environment were not considered. There are potentially a large number
of buildings contaminated with small amounts of tailings where the
contribution to indoor radon levels from the tailings is but a small
fraction of the indoor radon levels from natural causes. It is not
practical to locate these buildings (expensive and time consuming
measurements are required). Furthermore, remedial measures applied to
these buildings would realize very marginal benefits at high cost.
Least-cost standards were not considered because these leave large
amounts of tailings in close proximity to people and unjustifiably high
risks continue indefinitely, even after the buildings are torn down and
replaced.
Each standard sets requirements for indoor radon decay products
and gamma radiation levels and also specifies when active or passive
control methods are advised. The indoor radon decay product
concentration, measured in working levels, is used because it is a
measure of the health hazard resulting from tailings misused in
construction. We established a gamma radiation level criterion because
gamma radiation is also a health hazard and occasionally gamma
radiation levels are high even though the indoor radon decay product
levels may be low.
Alternative Standards Bl, B2, and B3 achieve a balance of costs
and benefits primarily through the discretionary use of low cost active
105
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remedial measures when the criteria are only slightly exceeded. In B4,
the balance is achieved by a flexible numerical standard which allows
broad discretion as to whether to use remedial methods within a range
of criteria. However, B4 does not permit the use of active measures.
Alternatives Bl and B2 are based on a single numerical decay
product concentration above which remedial action is required.
Alternatives B3 and B4 are based on two numerical decay product
concentrations; for buildings exceeding the highest level, remedial
action is required; for buildings exceeding only the lower level,
action is optional but encouraged if cost effective.
The alternative standards for cleanup of buildings are as follows:
Alternative Bl (The EPA standard proposed in April 1980).
Remedial action is required if a building contains tailings and
the indoor radon decay product concentration exceeds 0.015 WL
(including background). Tailings are removed (or active remedies
applied when the level is only slightly exceeded) until the indoor
level is below 0.015 WL (including background) or no tailings
remain.
Alternative B2. Remedial action is required if a building
contains tailings and the indoor radon decay product concentration
exceeds 0.02 WL (including background). Tailings are removed (or
active remedies applied when the level is only slightly exceeded)
until the indoor level is below 0.02 WL (including background) or
no tailings remain.
Alternative B3. Remedial action is required if a building
contains tailings and the indoor radon decay product concentration
exceeds 0.02 WL (including background). A building qualifies for
possible remedial action at 0.005 WL (above background). Active
controls are used when the required remedial action level is only
slightly exceeded.
Alternative B4. Remedial action is required if a building
contains tailings and the indoor radon decay product concentration
is 0.05 WL (above background). A building qualifies for remedial
action at 0.01 WL (above background). Active remedies are not
used.
Alternatives Bl to B4. For each of the alternatives, exposure to
indoor gamma radiation cannot exceed 20 microroentgens/h above
background. (This should require the removal of tailings when
large amounts are present but allow smaller amounts to remain when
they do not contribute significantly to indoor radon.)
For each alternative, we .show in Table 7-1 our estimates of the
number of buildings in the United States requiring remedial action,
106
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cleanup costs, and health benefits. For B3 and B4, which include a
range over which remedial action is optional, the cost estimates were
derived by assuming a value within the range which would typically be
achieved and costing controls to reach this level. For B3, we assumed
that at least 0.015 WL (including background) would be achieved. For
B4, we assumed that at least 0.03 WL would be achieved.
The extent of contamination of buildings as well as the cleanup
costs will not be known in detail until the cleanup program is well
underway. Therefore, we used the Grand Junction remedial action
program as the basis for our estimates. Appendix B contains a summary
of the Grand Junction experience and the cost calculations which
support the estimates in Table 7-1.
The cost estimates for each alternative standard are determined by
the number of buildings requiring remedial work and the cost per
building. As the remedial action criterion is lowered, more buildings
will need to be cleaned up, increasing costs. A lower criterion also
increases the cleanup costs per building since this requires more
complete tailings removal. In many cases, successive actions are
needed when the first remedial action does not meet the cleanup
criterion. Using active measures to meet a cleanup criterion when the
level is only slightly exceeded is much cheaper than tailings removal,
roughly one-tenth as costly.
The benefit of cleaning up contaminated buildings is expresed by
the number of lung cancer deaths avoided. This is estimated by
assuming the risk factors discussed in Chapter 4 are appropriate, an
initial distribution of decay product levels in contaminated buildings
identical to that for the buildings monitored in Grand Junction, a
50-year average useful life remaining for the stock of contaminated
buildings, and a 3-person household size. Also, benefits of cleanup
are expressed by the maximum residual risks to people living in the
buildings. This risk to an individual is calculated assuming lifetime
exposure to radon decay products at the highest level each alternative
standard allows.
7.2 Alternative Cleanup Standards for Near-site Contaminated Land
We have analyzed four alternative cleanup standards for near-site
(on the site or adjacent to the site) contaminated lands. All have
requirements that limit the amount of radium contamination because the
presence of radium is a reasonable index of the health hazard,
including that due to toxic chemicals as well as other radionuclides.
Alternative LI approaches a high-cost nondegradation alternative;
below this proposed radium limit it is usually not possible, using
conventional survey equipment, to accurately distinguish between
contaminated land and land with high naturally-occuring levels of
radium. Alternatives L2 and L3 approximate optimized cost-benefit
standards, but L2 demands a more rigorous cleanup of the soil
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TABLE 7-1. COSTS AND BENEFITS OF ALTERNATIVE CLEANUP STANDARDS FOR BUILDINGS
(in 1981 dollars)
Alter-
native
Stan-
dards
Radon Decay
Product Limit
(WL)(a)
Number of
Buildings Re-
quiring( }
Cleanup
Total Cost
(millions of)
dollars)
Deaths
Avoided , *
(in first 50y)
Estimated
Residual Risk ,,,
of Lung Cancer
Bl 0.015 370
B2 0.02 330
B3 0.005 (above 420
background)
to 0.02
B4 0.01 (above 350
background) to 0.05
(above background)
11.5
8.5
9.0
9.5
65
60
65
55
0.8 in 100
1.3 in 100
1.3 in 100
5 in 100
'a'The specified value includes background unless otherwise noted. Background in Grand
Junction is approximately 0.007 WL.
'"•'See Section 3.4. For Alternative B4, which is identical to the Grand Junction criteria for
action, we assumed the geometric mean of our two extreme estimates for the number of buildings
requiring remedial action. Assuming the distribution of radon decay product levels will be the
same as in Grand Junction, the number of buildings in the United States requiring action was
adjusted for the other options.
^c'Based upon the relative risk model. Estimates based upon the absolute risk model are a
factor of two lower. Health benefits attributable to reductions in gamma radiation levels arc
much smaller and have not been quantified.
^"•'Lifetime risk to the individual living in a house at the radon decay product concentration
limit. This risk is calculated after subtracting background from the level permitted by the
standard.
108
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surface. Standard L4 is a least-cost alternative that allows high
radiation levels that are close to Federal Guidance recommendations for
exposure of individuals to all sources of radiation excepting natural
background and medical uses.
The four alternative standards are:
Standard Ll. (The standard proposed in April 1980). Land should
be cleaned up to levels not exceeding an average 5 pCi/g of
radium-226 in any 5-cm layer within 1 foot of the surface and in
any 15-cm layer below 1 foot of the surface.
Standard L2. Land should be cleaned up to levels not exceeding an
average of 5 pCi/g in the 15-cm surface layer of soil, and an
average of 15 pCi/g over any 15-cm depth for buried contaminated
materials.
Standard L3. Land should be cleaned up to levels not exceeding an
average of 15 pCi/g in any 15-cm depth of soil.
Standard L4. Land should be cleaned up to levels not exceeding an
average of 30 pCi/g in any 15-cm depth of soil.
In Table 7-2 we list the estimates of the costs and benefits of
each alternative standard for near-site contamination around inactive
tailing piles. In each standard, the only remedial method for which we
estimated cost was the removal and disposal of contaminated soil, since
this is generally less costly than placing earth cover and vegetation
over contaminated areas and excluding access by fencing. The benefits
are expressed by (1) the number of acres of land that are cleaned up
and returned to productive use, and (2) the typical maximum residual
risk to individuals living in houses that might then be built on this
land.
The number of acres requiring cleanup under each option was based
upon the results of the EPA gamma radiation survey of twenty inactive
mill sites (Table 3-4). By assuming a typical depth profile of the
radium contamination, it is possible to relate the gamma radiation
levels measured by the survey to the areas of land contaminated above a
specific concentration level of radium. If the top 15-cm layer of
earth is uniformly contaminated with 30 pCi/g of radium, the gamma
field at the surface would be 63 percent of the gamma flux from an
infinitely thick layer, or 34 microroentgens/hr (He78). However, if
the 30-pCi/g average in the top 15 cm of earth is due to a thin surface
layer of nearly pure tailings of a few hundred pCi/g, the resulting
gamma radiation at the surface would be about 54 microroentgens/hr.
Since we expect windblown contamination profiles to be somewhere in
between these extremes, we estimate that, on the average, 44
microroentgens/hr above background (385 mrem/y) implies 30 pCi/g radium
contamination in the top 15 cm of soil (Standard L4). Similar analyses
for Alternative Standards Ll, L2, and L3 result in 3. 7 and
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TABLE 7-2. COSTS AND BENEFITS OF ALTERNATIVE CLEANUP STANDARDS FOR LAND
(in 1981 dollars)
Alterna-
tive
LI
L2
L3
L4
Radium-226
Soil Concentra-
tion Limit
(pCi/g)
5
5 to 15
15
30
Number of
Acres Re-
quiring
Cleanup1 ;
2700
1900
900
250
Total Cost
(millions of)
dollars)
21
14
7
2
Estimated
Residual risk
of Lung Cancer * '
2 in 100
2 in 100
6 in 100
10 in 100
(a)Areas of land near inactive tailings piles that have radium contamination
in excess of the soil concentration limit.
'The lifetime risk of lung cancer to the individual living in a house
built on land contaminated to the limits allowed by the alternative stan-
dards. This is based on the relative-risk model; use of the absolute-risk
model gives risks which are about a factor of two lower.
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22 microroentgens/hr, respectively (or 26, 61, and 193 mrem/y,
respectively). Additional deeper contamination would yield only
slightly higher gamma values because of shielding by the surface
layer.
Using these correlations between radium contamination levels and
gamma radiation levels, the areas requiring cleanup under each standard
were estimated based on the EPA survey data. The total costs of
cleanup were then calculated assuming a cleanup cost of $7650 (1981
dollars) per acre. This cost was estimated from EPA field experience
(a cleanup program at the Shiprock mill site) and is in agreement with
cost estimates of DOE contractors. Areas of heaviest contamination,
such as the ore storage area and mill buildings, are excluded from this
analysis since we have included them in the analysis of disposal costs
for the piles.
The highest risk to people living in houses built upon contami-
nated land is due to the inhalation of radon decay products from radon
that seeps into the house. In the worst case, Standards Ll and L2
would allow thick-surface earth layers with 5 pCi/g contamination,
while Standards L3 and L4 would allow thick layers of contaminated soil
at 15 pCi/g and 30 pCi/g, respectively. On the average, houses built
on such 5 pCi/g earth would be expected to have indoor radon decay
product levels of about 0.02 WL. Houses with poorer-than-average
ventilation would have higher levels, while well-ventilated houses
would have lower levels. Houses built on land more heavily
contaminated than 5 pCi/g would have higher average indoor decay
product levels in proportion to the contamination. The estimated risks
due to lifetime exposure from these levels are listed in Table 7-2.
These are maximum estimates since most contaminated land away from the
immediate mill sites (where houses might be built) has only thin layers
(a few tens of centimeters) of contaminated material.
The gamma radiation levels to individuals permitted under the four
alternative standards are 80 mrem/yr for Ll and L2, 240 mrem/yr for L3,
and 470 mrem/yr for L4. This assumes a thick layer of contaminated
material over a large area at the maximum permitted levels of radium
concentrations. These doses would lead to increased risk of many kinds
of cancer, but this increase would be small compared to the lung cancer
risks due to radon decay products.
7.3 Alternative Cleanup Standards for Offsite Properties
Tailings on offsite properties which are not associated with
building construction are usually there because someone transported
them from a tailings pile. Examples of this kind of misuse are
tailings used as fill around fence posts and sewer lines, as the basis
for sidewalks and driveways, and as conditioners for soil in gardens.
Most tailings misused in this way are still concentrated; they are not
diluted by large quantities of earth or spread thinly over large areas.
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The major hazard stems from the chance that indoor radon levels
will be high in new buildings constructed on contaminated offsite
properties. There could also be a significant gamma radiation hazard
if people spend a lot of time close to the tailings.
We expect that offsite properties where tailings were misused will
typically exceed all the radium concentration limits specified for land
contamination in Alternative Standards LI through L4. Therefore,
virtually all of the 6500 contaminated sites identified in Chapter 3
would require cleanup under any standard. Based on engineering
assessments and similar cleanup work near a mill site in Edgemont,
South Dakota, we estimate it would cost $6,000 to clean up each of
these properties. This implies a total cleanup cost of $39 million.
However, many of these sites are unlikely to cause a significant
present or future hazard, either because of their location or because
the quantity of tailings involved is so small. Cleaning up such sites
implies high cost without significant benefits.
It is consistent and simple to use the same numerical cleanup
criteria for offsite contamination of properties as for near-site land
contamination. Since some offsite contaminated properties present a
minimal hazard and would cost a great deal to clean up to any
reasonable radium concentration criterion, additional criteria are
considered in one of the following alternative standards for
contaminated offsite properties:
Standard Pi: Offsite properties should be cleaned up to the same
levels as near-site land,^' with no exceptions.
Standard P2; Offsite properties should be cleaned up to the same
levels as near-site land,.with the following exceptions:
a. When contamination levels averaged over 100 m^ are less
than the action levels required for near-site lands.
b. When the hazard from the tailings is judged to be in-
significant because of location.
Small amounts of tailings will be eliminated from consideration if
levels are averaged over an appropriate area. For Standard P2 we have
selected 100 m^ as a reasonable area for this purpose since this is
the typical area of the foundation of a house. Thus, risk levels
allowed under Standard P2 should be no higher than the risks allowed
under the corresponding near-site land cleanup standard. Additional
sites will be eliminated under Standard P2 because of their location.
(!) Alternative Standards LI, L2, L3, or L4; whichever is selected as
a land cleanup standard.
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Based on an analysis of misused tailings that are not associated
with buildings (Section 3.4), we estimate that, because of location or
small quantity, Standard P2 would not require the cleanup of minor
locations such as under sidewalks or around fence posts. Also, we
estimate that half of the garden beds, yards, and detached buildings in
which tailings were used and one-fourth of all driveways with tailings
under them would not require cleanup. This would eliminate approximately
4,000 sites and save about $24 million, for a total cost of about
million.
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Chapter 8: SELECTING THE STANDARDS
In this chapter we compare alternative disposal standards for
tailings piles, cleanup standards for buildings, and cleanup standards
for land in light of the findings of Chapters 6 and 7. When reasonable
to do so, these alternatives were chosen to span three approaches to
environmental standards: nondegradation, cost-benefit, and least
cost. We consider the relative benefits, costs, and other factors for
these alternatives, and then select preferred standards.
In the preamble to the Act Congress stated the finding that
tailings "...may pose a potential and significant radiation health
hazard to the public [and] that every reasonable effort should be made
to provide for stabilization, disposal, and control in a safe and
environmentally sound manner...in order to prevent or minimize radon
diffusion into the environment and to prevent or minimize other
environmental hazards from such tailings." The Environmental
Protection Agency was directed to set "...standards of general
application for the protection of the public health, safety, and the
environment" to assure that these objectives will be met.
The Committee report accompanying the Act expressed the view that
remedial actions should be effective for more than a short period of
time. It stated that "The committee believes that uranium mill
tailings should be treated...in accordance with the substantial hazard
they will present until long after existing institutions can be
expected to last in their present forms," and that "The Committee does
not want to visit this problem again with additional aid. The remedial
action must be done right the first time." (H.R. Rep. No. 1480, 95th
Cong., 2nd Sess., Pt. I, p. 17, and Pt. II, p. 40 (1978).) In addition
to considering benefits, costs, and other factors, we reviewed the
alternatives in the light of these views.
Our analysis of the hazards from tailings shows that they arise
mainly from tailings that have been removed from piles by people and
used in or near buildings and from radon emissions to the outdoor air
from the piles. In addition, long-term weathering of unprotected piles
will spread tailings, thereby increasing radon emissions and
contaminating nearby land. Environmental contamination also can occur
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if radioactive or toxic chemicals from tailings enter surface or
underground water, although the potential for this depends strongly on
individual site characteristics. Floods could spread tailings over
river valleys at some sites. All of these hazards will persist for an
almost indefinite time. The total benefits from controlling tailings
will depend, therefore, on the length of time disposal remains
effective.
Some parts of the standards address control of more than one of
these hazards. For example, a standard requiring control measures that
substantially reduce radon emissions from tailings piles will also
inhibit wind and water erosion. Furthermore, durable covers are
generally thicker and more difficult to penetrate than covers designed
to last for only a relatively short period of time, so that a standard
for longevity of disposal is related to the likelihood that tailings
will be removed for inappropriate uses. Such relationships should be
borne in mind in the following discussions of alternative standards.
8.1 Standards to Control Tailings Piles
In Chapter 6 we selected three types of criteria with which to
specify standards to control tailings piles. These are longevity of
disposal, the radon emission limit, and measures to protect water
quality. When these are chosen, all of the various hazards from
tailings are controlled to some degree.
8.1.1 Longevity of Control
By longevity we mean the minimum period of time that tailings
piles are required to be stabilized. In general, barriers would be
placed between the tailings and the environment to accomplish this; the
longer the specified time, the thicker, more massive, and more
conservatively designed would be the barrier. Also, the longer the
time specified the more likely it becomes that the implementing
agencies would find it necessary to place primary reliance on passive
rather than active control measures.
We have concluded that standards that specify periods longer than
10,000 years would be impractical. Providing a reasonable expectation
of compliance over such long periods, if possible at all, could be done
only by burying the tailings several hundred feet or more beneath the
earth's surface, where long term changes are likely to be gradual and
predictable, or in shallow pits in exceptionally favorable locations.
For reasons described in Chapters 5 and 6, deep burial of uranium
tailings is not usually practical. However, if standards were to apply
for 10,000 years or more, no other disposal method appears to be
adequate.
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In Chapter 6 we considered six alternative standards for longevity:
a) 1,000-10,000 years (Alternative A),
b) at least 1,000 years (Proposed Standard); or, for
an indefinitely long time (unspecified) of at
least 1,000 years (Alternative C),
c) 200-1,000 years, relying primarily on passive
control methods (Alternative B),
d) an unspecified long time, relying on active
control methods for the first 100-200 years
(Alternative D), or
e) 100-200 years only, relying primarily on active
methods (Alternative E).
These alternatives can be viewed as either performance or design
standards. Compliance with performance standards is verified by
monitoring and assured through maintenance. We do not believe it is
reasonable to rely on performance standards for more than one or two
centuries. Therefore, alternatives that specify longer time periods
must be viewed as design standards. That is, the designers of a
control system would plan it to last for the required period with
"reasonable assurance" by considering the physical properties of the
disposal system and the environmental stresses to which it would be
subjected.
In order to estimate the relative benefits of the different
alternatives, we have assumed that any control system will be at least
partially effective for longer than the minimum design period. As
indicated in Table 6-6 we expect the total benefits to be much greater
under the Proposed Standard and Alternatives A, B, and C than under
Alternatives D and E, since systems relying heavily on institutional
controls would probably degenerate more quickly when care is no longer
required.
It appears technically feasible to isolate most tailings piles for
at least 1,000 years on the earth's surface. The primary threat to
stabilization during this period is flood damage. Engineering methods
for protecting tailings against floods are available. These
engineering methods, however, may not be applicable at every inactive
site, and they do not remain effective indefinitely. The longer the
time for which flood protection is required, the more likely it is that
piles will have to be moved to safer sites. As the longevity
requirement is increased, we postulate that more tailings piles would
have to be moved to new sites to provide reasonable assurance that
surface control will remain effective. Moving piles increases the
total costs of control rapidly. This general trend is reflected in
Table 6-2.
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Prevention of Misuse of Tailings
We have seen (Chapters 3 and 4) that the most significant hazard
is the potential for misuse of tailings in or near buildings. We
presume tailings will continue to be attractive indefinitely to people
for such purposes if they are unaware of or unconcerned about the
hazard. However, we do not consider standards containing criteria that
directly address misuse to be practical. Instead, we address the issue
through the implied access-inhibiting properties of methods needed to
satisfy the criteria for degree of longevity of disposal and radon
control.
The Proposed Standard and Alternatives A and B require a high
degree of longevity and radon control. This is most likely to be
achieved through use of thick earthen covers. As we noted in Chapter
5, thick earthen covers should significantly discourage unauthorized
access to the tailings. Furthermore, tailings under thick covers are
unlikely to be exposed inadvertently by people who dig into the cover
for other reasons.
Alternative C incorporates a requirement for long-term integrity
of the tailings control system, with emphasis on protection against
floods. The less stringent radon emission limit, however, can be
satisfied with relatively thin covers that would provide little
security against intruders. Depending on other site-specific
requirements, there may not be sufficient stabilization of the cover
provided (e.g., rock cover) to constitute a significant barrier to
intrusion without resorting to active (institutional) controls.
In Alternatives D and E control is designed to last for only a few
centuries, and depends upon use of cheaper active measures. The
physical properties of the required cover would provide virtually no
protection against intrusion.
Prevention of Erosional Spreading of Tailings
All the alternatives control wind and water erosion to some
degree. The major difference among the alternatives is the length of
time over which erosion is prevented. The costs, too, depend on
longevity because the longevity criterion determines the degree of
resistance of the cover to erosion, and, therefore, the quantity and
quality of cover material that must be used.
The Proposed Standard and Alternatives A through C would control
erosion effectively for periods much longer than the minimum longevity
requirements. Alternative D is a non-numerical standard requiring a
durable surface on the pile and any needed maintenance for 100 years.
It would therefore include control of wind and water erosion of
tailings for at least 100 years, but for an uncertain period of time
beyond. Alternative E requires surface stabilization for a period of
100 to 200 years. Occasional small releases of tailings due to
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spontaneous or gradual localized containment failures should be
expected; otherwise, this alternative would be tantamount to a much
longer longevity requirement, because methods that prevent localized
releases for 100-200 years would be generally effective for much
longer. Under Alternative E, minor breaks in the cover are assumed to
be repaired periodically over a period of 100-200 years.
8.1.2 Control of Radon Emissions
The six alternatives analyzed in Chapter 6 specify four radon
emission control levels:
a) to emission rates near background (2 pCi/m^s)
(Proposed Standard and Alternative A),
b) to 20 pCi/m2s (Alternative B),
c) to 100 pCi/m2s (Alternative C), or
d) no requirement (Alternatives D and E).
Under Alternatives C, D, and E, radon concentrations in air above
the tailings and for some distance around each site would not meet
Federal standards for unrestricted access by the general public. NRG
regulations, based on Federal Radiation Protection Guides, specify that
members of the general public shall not be exposed to radon
concentrations greater than 3 pCi/liter. Therefore, monitoring and
land-use restrictions would be needed for adequate public health
protection under these alternatives. The Proposed Standard and
Alternative A would reduce radon emissions so that such restrictions
would be unnecessary. Under Alternative B, radon emissions from the
piles would be of concern only under the most unfavorable circumstances
(residency on the tailings).
Under the Proposed Standard and Alternative A, emissions from the
tailings piles would be reduced by more than 99 percent. This would
eliminate most of the risk to nearby individuals as well as most of the
cumulative effects on populations. Alternative B would reduce
emissions by 96 percent, resulting in a maximum individual risk of
about one in a thousand. Alternative C would reduce emissions by 80
percent, but the maximum risk to nearby individuals would be about 1 in
200. Alternatives D and E do not directly limit radon emissions, but
the surface stabilization required should reduce emissions by about 50
percent, leaving a maximum individual risk of a few parts in 100.
Costs of Limiting Radon Emission
Since longevity, radon emission, and water protection requirements
differ among the alternatives, it is not possible to isolate the costs
of radon emission control alone. For example, if all other aspects of
controlling tailings piles are held constant, we estimate the total
cost of applying 1 meter of earth to all 24 piles to be $18.5 million.
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From Figure 5-1 we can determine how much radon emission would be
reduced by adding one meter of earth. If the only benefit of thicker
covers were to reduce radon emissions, we would find the
cost-effectiveness of each additional meter of earth to be considerably
less than that of the first meter. But thick covers have additional
benefits: they last longer than thinner covers and are barriers
against intrusion. Therefore, the net benefits of reducing radon
emissions cannot be isolated.
The disposal cost analysis in Chapter 6 applies only under the
stated assumptions. If local earth near a pile is very sandy, or if
suitable earthen materials are not available nearby, then satisfying
the Proposed Standard and Alternative A, which have the strictest radon
emission control level, could require several additional meters of
cover. Conversely, if earthen materials are more easily available or
of higher quality (i.e., clays) than is assumed, the costs will be
lower. Because of the lack of full-scale disposal experience, however,
there is a greater risk of the cover requirements for the Proposed
Standard and Alternative A being significantly underestimated than for
Alternatives B through E.
NRC (NRC80) has evaluated the potential environmental impacts of
obtaining cover materials in regions where uranium is mined. As a
rule, the environmental impacts will be greatest for the Proposed
Standard and Alternative A, less for Alternative B, and least for
Alternatives C through E. Even under relatively unfavorable
conditions, however, the effects are largely temporary; the
longest-lasting effects are changes of topography at borrow sites for
the cover material. This issue is highly site-specific, however, and
definitive information on the environmental effects of obtaining cover
materials at the 24 inactive sites is not yet available. We expect
such effects will be small overall, but the Proposed Standard and
Alternative A are the most likely to cause significant temporary
environmental disturbances.
Form of the Radon Standard
We have expressed the radon limit in terms of the release rate per
unit area from the tailings. However, a number of alternative criteria
could be used to control radon emissions from the piles:
a) dose rate limits for individuals or populations,
(mrem/y, person-rem/y, person-WLM/y),
b) radon concentration limits in air (pCi/1),
c) total radon release rate limits (pCi/s), and
d) release rate limit per unit area (pCi/m^s).
Because short-term fluctuations are unimportant, we will consider all
of these as annual averages. Radon emissions from tailings to the air
cannot be separated from those *from a cover or normal land, however.
Therefore, a standard using any of these criteria must apply to either
the total radon release rate from the surface of a pile or to the radon
release rate from tailings with allowance being made for the radon
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from the cover and other land. These alternative criteria are
discussed briefly below:'
a) Dose or exposure rate standards for individuals can be related
directly to risk. They could be satisfied by restricting emissions or
by restricting occupancy in areas where the standards might be exceeded.
Such standards would permit flexible implementation and might be
inexpensive in practice because they can be satisfied by land-use
restrictions rather than physical control. Limits on population
dose would be hard to implement, however, because of relatively
high-cost continuing data-gathering and modeling requirements. Whether
for individuals or populations, dose rate standards require calculating
or measuring quantities that may be small compared to natural background
values. Such standards would need oversight by the implementing agency
for as long as the standard applies, unless the disposal permanently
reduces radon emissions to levels at which no restrictions on occupancy
would be ever needed. We rejected these approaches as impractical for
this long-term hazard.
b) Radon concentrations in air are easily measured but highly
variable and unpredictable, and it is difficult to distinguish the
radon coming from piles from the natural radon background. A practical
standard would have to be significantly higher than normal background
levels, and, therefore, could apply only very close to the tailings,
where it would still be a highly variable quantity, subject to a
variety of meteorological parameters. We rejected this alternative as
offering no advantage over criterion d, which is more closely related
to the total emission of radon.
c) A standard that limits the total radon release rate from each
pile would not take into account significant differences among the
piles. Piles of different areas would need different thicknesses of
cover material to meet the standard. This alternative would place
unreasonable control requirements on large piles or permit inadequate
cover on small piles to control individual dose and discourage
intrusion. Furthermore, the total radon release rate must be estimated
from the release rate per unit area (criterion d, below).
d) A limit on release rate per unit area can be applied uniformly
to all sites. It is also the most meaningful criterion for comparing
the emissions of a pile with that of normal land. It is, however,
relatively difficult to measure and varies considerably with location
on the pile, climate, time of day, and other factors. The release rate
per unit area can be estimated, however, from the radium and moisture
contents of a pile and its cover (NRC80, Mob79), averaged over suitable
times and areas.
As indicated above, checking compliance with these standards by
direct measurements could be very difficult. This reinforces our
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belief (see Section 8.1.1) that compliance should be demonstrated
through the design rather than the performance of the tailings control
system.
8.1.3 Protection of Groundwater Quality
Since most inactive uranium processing sites are in dry climates,
much of the water that may ever infiltrate them has already done so
during the operating period of the mill. However, some tailings piles
are in contact with groundwater during periodic elevations of the water
table, and one pile is located in a wet climate. Nonetheless, although
studies of the inactive sites are inconclusive, they provide little
evidence that radioactive and nonradioactive toxic substances are
moving from any of the piles to groundwater. Elevated levels of toxic
substances have been found in wells near some active mills, but seepage
pathways from the tailings ponds are not always unequivocally implicated
(UI80). Further, seepage is much less at inactive sites, and there is
evidence that geochemical mechanisms help prevent many contaminants
from entering groundwater (MacSla).
Groundwater is used for drinking, irrigating crops and watering
livestock, and industrial purposes. Existing national water quality
standards for these uses apply to surface waters and public drinking
water supplies. There are also no national standards for some uses of
water containing certain potentially hazardous substances found in
tailings, such as molybdenum and uranium.
Disposal standards for protecting groundwater near inactive
uranium mill sites must be considered, therefore, in the context of
uncertain hazard and incomplete regulatory precedents.
Alternative Approaches to Groundwater Protection
In Chapter 6, we analyzed four basic approaches to protecting
gr oundwater:
a) nondegradation: establish standards to protect water of
drinking quality and do not increase toxic levels of
lower quality water (Proposed Standard);
b) highest use: establish standards to protect the highest use
for which water is potentially suitable (Alternative A);
c) site-specific: do not establish general standards, but require
site-specific determinations of potential hazards and uses, and
1) preventive action, guided by State and Federal criteria
and other requirements (Alternatives B and C), or
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2) prevention of significant water movements
from tailings to groundwater or treatment of any
contamination at the point water is used, depending on
which method is less costly (Alternative D); or
d) no standards: do not address groundwater protection
(Alternative E).
These approaches refer to the long-term potential of tailings
piles to contaminate groundwater after disposal. We discuss the
possibility of remedial actions for previous releases from the piles in
Section 8.1.5.
Nondegradation
The nondegradation approach (Proposed Standards) is the most
protective we consider. After a tailings pile is disposed of,
concentrations of specified toxic contaminants in groundwater could not
(1) exceed the safe level for drinking water, or (2) increase, if these
levels are already exceeded. The standards would apply to aquifers
that now supply drinking water and others in which the concentration of
total dissolved solids is less than 10,000 milligrams per liter. The
requirements would apply 1 km from tailings disposed of at an existing
site, or 0.1 km from a tailings pile moved to a new site.
Most of the specified contaminants are inorganic substances
covered by the National Interim Primary Drinking Water Regulations
(NIPDWR) (EPA76b). Uranium and molybdenum, which may have serious
toxic effects on humans, animals, or plants, are abundant in tailings
and expected to be environmentally mobile, but are not covered by the
NIPDWR. This deficiency requires us to determine human health
protection levels for these substances, which we believe could be
widely misinterpreted and applied as equivalent to new Primary Drinking
Water Regulations. Since PDWR are based on toxicity, prevalence in
water systems, practicality of analytical methods, and treatment costs,
such confusion would be unfortunate. Standards for public drinking
water supplies have much larger health and economic significance than
standards for controlling uranium tailings at the 24 inactive mill
sites.
A nondegradation approach would be very restrictive. Water that
is already highly contaminated would be protected from further
degradation without regard to its usefulness, and without site-specific
consideration of the benefit of water protection measures that may be
very costly. However, tailings piles disposed of in accordance with
the "nondegradation" standard should not cause groundwater "problems"
for people in the future, whereas one cannot be as sure that more
lenient standards will be adequately protective.
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Any approach depending on generally applicable numerical standards
may be difficult to implement at certain sites because our ability to
perform hydrological assessments is limited. Studies of active mills
suggest that uranium processing sites are often difficult to
characterize hydrologically. For some sites in dry climates "reasonable
assurance" that a numerical standard will be satisfied may be based on
a simple water balance analysis—i.e., a showing that there is no net
downward flow through the tailings. More complex analyses may be
needed when groundwater is in contact with the tailings, or where the
climate is wet. However, state-of-the-art analyses may not be
sufficiently conclusive to avoid specification of very expensive
disposal methods, such as moving piles to new sites and/or installing
liners, because the complete absence of a significant threat to ground-
water cannot be demonstrated.
Highest Use
Groundwater would be protected for the highest use for which it is
potentially usable. Standards would be needed for various uses. As
indicated above, there are national standards (the NIPDWR) for drinking
water quality, but they do not cover molybdenum and uranium. EPA has
also published water quality criteria (NAS72, EPA76c) that provide a
basis for standards for different water uses; molybdenum and uranium
are not covered. All States have adopted either narrative or numerical
surface water quality standards under the Clean Water Act, but most do
not cover uranium and molybdenum. These numerical standards also
vary. Therefore, while there is a framework for establishing standards
based on use, there is no single or complete set of standards that can
be directly applied to groundwater near uranium mill tailings.
The "highest use" approach has the same effect as the
nondegradation approach for groundwater that meets or exceeds the
quality required by the NIPDWR, as both would permit degradation to the
NIPDWR limits. However, for water of lesser quality, the "highest use"
approach is more flexible. It permits degradation so long as the
usefulness of the water is not impaired. If the existing water quality
is marginal for some use, then it permits no increase in the
concentration of the substances whose concentrations are already
marginal for that use, but concentrations of other substances may
increase. Under this approach, however, other pollution sources may
combine with tailings effluents to degrade the usefulness of ground-
water resources.
It may be easier to implement a highest use approach than a
nondegradation approach. Similar techniques are needed, but the
required analytic precision is less.
Site-Specific Approaches^
Under this approach, EPA"would provide guidance, but the primary
responsibility for determining groundwater protection requirements
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would rest with the implementers. Providing such guidance recognizes
that general numerical groundwater standards may not be needed for this
program, that they are difficult to establish, and possibly difficult
to implement.
Under the first alternative for this approach, the guidance would
reference relevant precedents, but emphasize protecting groundwater
rather than treating it after the fact. The implementers would have
discretion to decide what constitutes adequate groundwater protection,
subject to the requirements of NEPA (National Environmental Policy
Act), existing State and Federal water quality criteria, and consonant
with the objectives of the EPA regulations under the Solid Waste
Disposal Act, as amended. Remedial actions at designated sites will be
selected and performed by DOE with the concurrence of NRC and the full
participation of any State that pays part of the cost (Section 108 of
the Act). Therefore, basic site-specific decisions on groundwater
protection under this alternative would be made jointly by several
parties, all having access to EPA's general guidance, and subject to
public review under NEPA.
The Act authorizes EPA to revise its remedial action standards for
inactive sites "from time to time." If further investigation of the
tailings sites revealed considerable real or potential groundwater
pollution, then EPA could issue generally applicable standards to
supplement the guidance. EPA is currently developing general ground-
water protection policies, especially for its remedial action and
disposal programs for hazardous materials under the Solid Waste
Disposal Act, as amended, and the Comprehensive Environmental Response
Compensation and Liability Act ("Superfund"). If the need should be
demonstrated, these policies, when adopted, could provide the basis for
groundwater protection standards under this Act.
A second site-specific approach is a narrative (non-numerical)
prescription to provide the lowest cost remedies for any groundwater
use that may be affected by contamination from tailings. The
implementers would have discretion regarding the manner and degree of
remedy, subject to the least cost criterion. They would decide the
significance of any contaminant movements in groundwater and determine
adequate treatment levels for various water uses. Under this
alternative there would be no specified limit on the degree to which
tailings could contaminate an aquifer, provided users of the water
could be compensated at a cost lower than that for preventing the
contamination. For example, if water treatment is not economic,
substitute water sources could be provided.
Since the extent of future use may be difficult to estimate, the
total cost of treating contaminated water may be impossible to
determine. The current costs of avoiding contamination might be higher
than the apparent treatment costs, yet, over a long time, cumulative
prevention costs might be lower. In addition, as noted in Chapter 5,
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physical control methods (prevention) are assumed to be more reliable
over a long term than institutional methods (treatment).
No Standards
Under this approach EPA would not issue standards or guidance for
protecting groundwater. This would be justified by concluding that
tailings piles at inactive sites are not significant sources of
groundwater contamination or that remedial actions to satisfy other
aspects of the standards would adequately protect groundwater. Such a
conclusion would be controversial. (Controlling radon emissions with
impervious covers, for example, would keep rain water from flowing into
a tailings pile. However, any contamination resulting from direct
contact of tailings with groundwater would not be affected by a
cover.)
The approach might simplify or complicate the remedial action
program, resulting in either cost and time savings or increases,
depending on site-specific circumstances. The implementers might
determine, for example, that groundwater protection assessments need
not be performed and successfully defend any attempt by others to
reverse that decision. On the other hand, they might determine that
such assessments are necessary to comply with NEPA. If a potential for
groundwater pollution were found, the implementers would not have
available either EPA standards or guidance.
8.1.4 Protection of Surface Water
Wind, rain, or floods could carry tailings into rivers, lakes, and
reservoirs. Pollutants may also seep out of piles or rise to the
surface and form toxic salt deposits. However, streams and rivers near
inactive uranium processing sites show very little contamination from
the (unstabilized) tailings piles. We expect any effects of stabilized
piles on surface water will be even less for as long as they remain
stabilized, since stabilized tailings will not be able to release
particulates to wind or water.
Seepage and salt deposits emerge from the piles gradually and are
periodically swept away (diluted) by rainfall. Such releases will not
necessarily have significant consequences, but they could adversely
affect the quality of nearby bodies of standing water, such as ponds.
However, there are only a few such ponds at the designated sites and
remedial actions can eliminate them or provide protective land contours.
Severe floods could spread large quantities of tailings into
standing and flowing water, with possibly serious, though unevaluated,
consequences. A requirement to stabilize tailings for a long period of
time would provide good assurance that they not be subject to severe
damage by such floods.
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As long as disposal standards require surface stabilization that
includes protection against flooding of sufficient longevity, the need
for specific surface water protection standards appears marginal.
In Chapter 6 we analyzed four basic approaches to protect surface
water:
a) nondegradation: prevent increases in concentration
of any toxic substance in surface water (Proposed
Standard);
b) highest use: protect surface water for the highest
use for which it is potentially suitable (Alternative A);
c) site-specific:
1) provide guidance for avoidance of contamination
based on existing water quality criteria and other
regulations (Alternatives B and C), or,
2) require avoidance of significant water movement
from tailings to surface water (Alternative D); or
d) no standards: do not address surface water protection
(Alternative E).
The nondegradation approach formed the basis for the Proposed
Standards. The surface water requirements of that standard would
require any potentially harmful contaminated water from the tailings to
have a lower concentration of contaminants than the surface water it
entered. This requirement would apply to all harmful contaminants,
some of which are present only in very low concentrations in surface
water. This would require very strict control of releases to surface
water of at least these substances. Thus, this approach could require
avoidance of even insignificant releases to any surface water,
regardless of its usefulness.
The "highest use" and "site-specific" approaches would have
essentially the same advantages and disadvantages as discussed for
groundwater under Section 8.1.3. The "no standards" approach could be
justified if no surface water contamination is possible when other
aspects of the standards are satisfied. However, the possibility of
toxic salt migration to the surface of tailings piles and subsequent
contamination of unprotected nearby bodies of standing water would not
be addressed.
8.1.5 Remedial Action for Existing Groundwater Contamination
There is evidence of limited existing groundwater contamination
at a few of the inactive sites. In Chapter 5 we referred to case
studies of remedial actions for hazardous waste disposal sites that
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have leaked contaminants to their surroundings. We conclude that the
practicality of such remedial actions must be determined site by site.
The Department of Energy will prepare environmental impact statements
or environmental assessment reports for each site to support its
decisions, with NRC's concurrence, on control methods. We expect DOE
to consider the need for and practicality of controlling contaminants
that have already seeped into the ground and to apply technical
remedies that are found justified. Institutional controls should also
be considered. If tailings are found to be contaminating groundwater
that is being used, we would expect DOE to consider providing alternate
water sources or other appropriate remedies. However, although it may
sometimes be practical to improve the quality of an already-contaminated
aquifer, we believe a generally applicable requirement to meet preset
standards is not feasible.
The Act will terminate DOE's authority 7 years after we promulgate
standards, unless Congress extends the period. However, Section
104(f)(2) of the Act provides for Federal custody of the disposal sites
under NRC licenses after the remedial action program is completed. The
custodial agency is authorized to carry out such monitoring,
maintenance, and emergency measures as the NRC may deem necessary to
protect public health. We expect NRC's requirements will be sufficient
to ensure detection of any contamination of usable groundwater near the
disposal sites, and to cause the custodial agency to take such measures
as may become necessary to avoid any significant public health problem
for the duration of the hazard.
8.1.6 The Preferred Standard for Control of Tailings Piles
The preferred standard is Alternative B (See Table 6-1, page
128). The longevity requirement is 200 to 1,000 years. Radon
emissions are limited to 20 pCi/m2s. Control measures would be
selected by the implementing agencies on a site-specific basis so that
relevant water quality criteria and other guidance are met to protect
ground and surface water.
The longevity and radon emission requirements combine to assure
that tailings control systems will have durable covers that should
inhibit unauthorized access to the tailings^) and prevent tailings
erosion by wind and floods. The radon emissions limit would reduce the
risk of lung cancer to low levels and permit unrestricted use of lands
adjacent to the disposal sites. The implementing agencies would assure
that any water protection issues that may arise at individual sites
will be resolved in the public's interest.
(i'We note that Sec. 104(h) of the Act anticipates authorized uses of
subsurface minerals at a tailings disposal site. It provides, however,
that any tailings disturbed by such use "will be restored to a safe and
environmentally sound condition.*" We propose, therefore to apply the
disposal standards to restoration of a site following the use of any
subsurface mineral rights acquired under the provisions of Sec. 104(h).
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We believe the Proposed Standard and Alternative A present greater
technical difficulties and costs and a higher risk of substantial
unplanned costs than are necessary or wise for this remedial action
program. The "nondegradation" standards would provide only marginally
greater benefits than Alternative B. Alternatives D and E, on the
other hand, do not require remedial actions that would yield
significant benefits, although such remedial actions can be carried out
for relatively small incremental costs. Tailings would remain subject
to dispersal by flood and misuse by people. That is, Alternatives D
and E require only short-term partial control of this long-term
problem, and far more permanent and effective controls are available
for small incremental costs. Alternative D would also be difficult to
codify and to implement because its requirements are vague.
We prefer a radon emission standard to other forms of standards
because of its direct relation to the cover requirements for tailings.
More so than for alternative forms of standards, the radon release rate
measures the quality of stabilization, the degree misuse is inhibited,
and the reduction of the risk for nearby individuals and the cumulative
risk for populations.
We prefer Alternative B to Alternative C because it provides
significantly greater protection against intrusion and radon emissions
at no increased cost. This is achievable primarily through sub-
stituting costs of more substantial cover and inplace flood protection
for costs of moving piles to new sites to avoid highly improbable
floods.
8.2 Standards For Cleanup of Buildings
Tailings that have been used in or around buildings are
particularly hazardous and may cause indoor radon decay product
concentrations that may be many times normal indoor concentrations.
Thus, we conclude that a standard should specify the maximum allowable
radon decay product concentration in buildings affected by tailings.
The standards should also specify gamma radiation levels because
tailings can cause high indoor gamma radiation levels without
necessarily causing high radon decay product concentrations.
8.2.1 Previous Indoor Radon Standards
Government agencies of the United States and Canada have published
several remedial action criteria for radon decay product concentrations
in buildings. The following brief review is provided to clarify their
relationship to the alternative standards in Chapter 7.
The U.S. Surgeon General's 1970 remedial action guidance for Grand
Junction, Colorado, applies to buildings on land contaminated with
uranium mill tailings (Pea70). EPA's guidance for the State of Florida
applies to buildings on radium-bearing phosphate lands (EPA79a). Each
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of these guides has two radon decay product levels that specify the
following: 1) above an upper level, action is required; 2) below a
lower level, action is not required; 3) between these levels, local
considerations must be used to determine the appropriate action.
The Surgeon General's Guides are implemented by 10 CFR 712, the
Department of Energy's regulations for remedial action at Grand
Junction, Colorado. In effect, they adopt the lower level as an action
level for remediation of schools and residences, and the midpoint
between the lower and upper levels as an action level for other
buildings. This difference recognizes that people occupy residences
and commercial buildings for different periods and that children should
have added protection. When radon decay product concentrations are
expressed in working levels (WL), these action levels are 0.01 WL and
0.03 WL, respectively, above background. The average indoor background
determined by DOE for Grand Junction's remedial program is 0.007 WL.
Canadian cleanup criteria (AEB77) and EPA's recommendations for
residences on phosphate lands in Flordia call for remedial action when
indoor radon decay product concentrations are greater than 0.02 WL
(including background). The EPA guidance further recommends that
concentrations below 0.02 WL be reduced as low as can be reasonably
achieved, but that reductions below 0.005 WL above the average normal
background (0.004 WL in Florida) are not generally justifiable. In
summary, EPA has recommended remedial action in Florida above 0.02 WL,
stated that action is generally unjustified at concentrations less than
0.009 WL, and left the degree of action at intermediate levels to the
judgment of local officials.
8.2.2 Indoor Radon
In Chapter 7, we analyzed four alternative criteria for indoor
radon in buildings:
a) an action level of 0.015 WL, including background
(the Proposed Standard, also called Alternative Bl);
b) an action level of 0.02 WL, including background
(Alternative B2, similar to the Canadian criterion);
c) a mandatory action level of 0.02 WL, including
background; cleanup would be discretionary for levels
between 0.005 WL above background and 0.02 WL
including background (Alternative B3, similar to
EPA's guidance for Florida phosphate lands); and
d) a mandatory action level of 0.05 WL above background;
cleanup would be discretionary for levels between
0.01 WL above background and 0.05 WL above background
(Alternative B4, similar to the Surgeon General's
guidance for Grand Junction, Colorado).
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The costs of meeting these alternatives were analyzed under a
variety of assumptions regarding remediation methods. The results
(Table 7-1) indicate that the costs and benefits of all the standards
are approximately equal. Even though these results are not definitive,
because the analysis was based largely on experience in Grand Junction
where conditions may be different from those to which these standards
will apply, feasibility of implementation and health risk appear to be
the most significant factors when choosing between the alternatives,
not cost. We also believe that the maximum risk permitted under
Alternative B4 is unacceptably high.
Effect of Variations in Background Radiation on the Choice of a
Standard
Indoor radon decay product concentrations in normal buildings vary
widely. Because of fluctuations in normal indoor radon levels, it is
often impossible to tell when small amounts of tailings are present
unless they can be detected by other means, such as through gamma
radiation measurements. Further, contaminated buildings vary in
location, design, materials, and patterns of use, all of which affect
indoor radon decay product concentrations. It is usually impractical
to determine the background level for a particular building, either
from measurements of unaffected buildings or by any other means. For
these reasons, an action level expressed in terms of an increment over
the background radon decay product concentration cannot be implemented
easily. U>
The closer the standard is set to median background levels, which
in the western and northeastern United States appear to range from
0.004 WL to 0.008 WL, the less effective will be remedial actions for
marginally contaminated buildings. In addition, an action level of
0.005 WL above "background" would often require remedial actions where
tailings are not the principal source of indoor radon. This is because
indoor radon levels in buildings that are not affected by tailings vary
from typical values by more than 0.005 WL (see Table 3-7). Thus,
efforts to reduce radon decay product levels by removing tailings would
not work well, and the money would be wasted. Even where tailings are
Table 3-7 shows, the background level of 0.007 WL determined
for use in the Grand Junction program is simply the median of
measurements of many buildings in Grand Junction that varied from 0.002
to 0.017 WL. The median background of 0.004 for the Florida phosphate
guidance was determined from measurements of similar houses in a
particular locale; the measurements varied from 0.001-0.012 WL. For
the inactive uranium processing sites program, where the affected
buildings are located in 10 States, any single "background" number
would be very unrepresentative, and determining the average background
separately for each affected community would be impractical.
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not the major cause of elevated radon levels, however, ventilation and
filtration devices would be effective in reducing radon decay product
concentrations.
A standard specifying the total concentration level of radon decay
products (including background) would have the advantage of providing
the same action level for all affected buildings, even though
background concentrations in one affected area may be higher than in
another. When the standard level is above the typical range of
variations in background levels, the standard would be simple and
definite.
Appropriate Remedial Measures for Buildings
Remedial methods vary in the degree they assure long-term
reductions in radon decay product concentrations. When risks are high,
it is reasonable to provide a greater degree of assurance by using
remedial methods that will not lose effectiveness if not maintained by
the building residents. Removing tailings from buildings permanently
reduces indoor radioactivity levels and cleans up the sites.
Filtration and ventilation devices, and other relatively low cost
remedial methods, whose long-term effectiveness depends on maintenance,
can provide reasonable assurance of compliance at a much lower cost
when the standard is only slightly exceeded.
8.2.3 Indoor Gamma Radiation
Tailings also emit gamma radiation. In general, we expect that
the indoor radon decay product standard will usually be met by removing
tailings from buildings and that this will eliminate any indoor gamma
radiation problem. However, in unusual cases (such as a
building that contains tailings, but is very well ventilated) a
standard limiting gamma radiation exposure may be needed. An action
level for gamma radiation of 0.02 mR/h above background'1) would
allow flexibility in the choice of methods for reducing indoor radon
decay product concentrations. Reducing this much below 0.02 mR/h would
virtually eliminate flexibility in remedial methods and provide only a
small additional health benefit to those few individuals who might be
affected. If the occupants of a building were present 75 percent of
the time, a level of 0.02 mR/h would allow gamma radiation doses from
tailings of about 130 mrad per year. This would allow about twice the
average annual background dose from gamma radiation in the regions
where most of the piles are located.
'1'Indoor background levels of gamma radiation are easier to
determine and less variable than radon decay product concentration
backgrounds.
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8.2.4 Preferred Cleanup Standard for Buildings
The most desirable cleanup standard for buildings would draw
elements from several of the alternatives analyzed. We conclude that
indoor radon standards should be expressed in terms of the total
concentration of radon decay products, including background, because
this quantity is unambiguous and does not require measuring each
community's background levels. Indoor gamma radiation standards should
be expressed in terms of the increment above background, however,
because gamma radiation is an important tool in detecting the presence
of tailings, and the background level in a building is relatively easy
to determine.
Our preferred cleanup standard for buildings has the following
characteristics:
Tailings would be removed from buildings having indoor radon decay
product concentrations above 0.03 WL. All practicable efforts should
be made to reduce concentrations further to within 0.02 WL by any
available means, including the use of relatively low cost air cleaning
and ventilation devices. Indoor gamma radiation exposure should not
exceed 0.02 mR/h above background.
Such a standard would require removal of tailings when indoor
radiation levels are well above normal background levels. Removal is
generally the mostly costly remedial method, however, so the standard
would permit the use of other remedial methods for,reducing radon decay
product concentrations below 0.03 WL. We believe remedial actions are
generally not warranted where radon concentrations are less than 0.02
WL, because tailings removal at these levels would often be ineffective
and very costly, and active remedial devices are more likely to be
required just to reduce background levels than for radon byproducts
from tailings.
Such a cleanup standard for buildings would require the
implementing agencies to reduce the occupants' exposure to radiation
from tailings to the lowest reasonably achievable level and to provide
reasonable assurance that the building sites will not pose hazards for
future replacement buildings.
8.3 Standards for Cleanup of Land
Uranium mill tailings from inactive sites have been spread by
wind, water, and people, thereby contaminating both nearby and distant
land. The hazard this poses to people is most conveniently related to
the concentration level of radium-226. Tailings on nearby lands
usually result from erosion and are now mixed with soil. They may also
occur at various depths. Therefore, a standard should specify the
concentration of radium-226 in soil (pCi/g), the depth of soil over
which this concentration criteria should be averaged (cm), and the
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thickness of the contaminated layer covered by the standard. Tailings
on distant lands were carried there by people for use, usually as
fill. These tailings were typically used without dilution with other
material, and there are now small deposits of tailings at many
thousands of locations.
8.3.1 Alternatives for Cleanup of Land
The greatest hazard from tailings on open land is due to the
possibility of increased levels of radon decay products in future
buildings built upon the land. Exposure to direct gamma radiation and
contamination of drinking water and food may also occur, but generally
this is of less concern.
In Chapter 7 we analyzed four alternative cleanup criteria for
radium-226 concentration in contaminated land near a tailings pile:
a) 5 pCi/g in any 5 cm layer within one foot of the
surface and in any 15 cm layer below one foot (the
Proposed Standard, also called Alternative Ll);
b) 5 pCi/g for surface deposits, 15 pCi/g for buried
materials, both averaged over 15 cm layers
(Alternative L2);
c) 15 pCi/g averaged over 15 cm layers, whether on or
below the surface (Alternative L3);
d) Same as "c," but 30 pCi/g (Alternative L4).
For distant lands, where tailings were likely to have been misused
in concentrated form, we considered two additional criteria:
e) use the same criteria as for nearby land
(Alternative PI);
f) use the same criteria as for nearby nearby lands with
the following exceptions (Alternative P2):
1) when contamination levels averaged over 100 m^
are less than the action levels required for
offsite lands; and
2) when the hazard is judged to be not significant
because of the location of the tailings.
We found that the projected maximum residual risk under all the
alternatives is undesirably high (see Table 7-4, for example), but is
particularly high for Alternatives L3 and L4. However, this maximum
risk is unlikely to occur, for several reasons. First, we estimated
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the risk by assuming that the highest acceptable radium concentration
persists deeply. In reality, tailings spread by erosion tend to remain
on the surface of the ground. Second, people usually clear a construc-
tion site in some manner, which would further reduce the amount of
residual tailings underneath a new building.
In view of these considerations, we believe that significantly
elevated radon levels in buildings on open land are unlikely to occur
under Alternatives Ll and L2. Elevated indoor radon levels are more
likely under Alternatives L3 and L4, and the residual gamma radiation
levels around the building would be high.
Cleanup costs for contaminated land adjacent to tailings piles
vary considerably for Alternatives Ll through L4. However, for
Alternatives L3 and L4, the lowest cost alternatives, people would
incur high risks from living in houses built upon land contaminated to
the maximum allowed by the standard. Furthermore, these alternatives
would be in conflict with the existing Federal radiation exposure
guidance of 500 mrem/y for an identifiable individual, and 170 mrem/y
for a group of persons not individually monitored.
EPA sought the opinion of an aci hoc group of radiation measurement
experts on the implementation of soil cleanup standards. Their report
(EPA81) indicates that portable field survey instruments can be useful
tools in implementing the surface contamination portions of
Alternatives Ll through L4. This would be important to minimize
remedial action costs. Subsurface contaminants can only be detected by
measurements in bore holes or on samples of subsurface material. This
is a relatively slow and expensive process, but it can be performed
with currently available techniques for any of the alternatives. There
is need for this only where there is reason to believe that tailings
may be buried.
Form of the Land Cleanup Alternatives
We expressed the alternatives in terms of a radium concentration
after considering the following options:
(1) radium concentration levels,
(2) gamma radiation levels,
(3) radon release rates,
(4) predicted radon decay product
concentrations in buildings.
All these would restrict residual radiation hazards, but
with the following advantages and disadvantages.
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(1) Radium concentration is directly related to the
hazard of most tailings. (Occasionally it is not
sufficient where other specific radioactive or toxic
elements in uranium ore processing residues have been
concentrated.) Quantities (2), (3), and (4) result
directly from the radium in tailings.
(2) Gamma radiation levels can be conveniently measured,
but they are related to only part of the hazard.
Tailings that are covered with a few feet of earth
could satisfy a gamma radiation standard, yet be
hazardous to build upon because of radon emissions.
(3) Radon emission is usually the principal hazard from
uranium mill tailings. Radon release rates vary
greatly with changes in weather and soil moisture,
however. A standard based on the radon release rate
would require repeated measurements over varied
conditions to determine meaningful averages.
(4) The predicted radon decay product concentration is
related to the hazard, but estimates of the indoor
radon decay product concentrations are very
uncertain. Furthermore, either the radium
concentration or radon release rate from the land
must first be determined to make such estimates, so
(4) offers no advantage over (1) or (3).
8.3.2 Preferred Cleanup Standard for Land
We prefer Alternatives L2 and P2 as cleanup standards for near and
distant land, respectively. Specifically, land should be cleaned up to
levels not to exceed an average of 5 pCi/g of radium-226 in the first
15 cm surface layer of soil and an average of 15 pCi/g of radium-226 in
any layer of 15 cm depth at deeper levels. Offsite properties should
be cleaned up to these same action levels, with the following
exceptions:
a) when contamination levels averaged over 100 m^ are
less than these action levels; or
b) when the hazard from the tailings is judged to be not
significant because of their location.
A 5 pCi/g limit over the first 15 cm can be easily implemented
with relatively low cost gamma radiation survey methods. For tailings
below 15 cm, the concentration limit of 15 pCi/g is also easy to
implement. Alternative Ll would require more skill and training of
personnel, and greater use of expensive measuring techniques, but
cleanup would only be marginally more complete. Very thick deposits of
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material with up to 15 pCi/g of radium-226 generally would be hazardous
to build on, but are unlikely to occur. A concentration of 15 pCi/g is
likely to occur only in thin layers at the edges of more concentrated
deposits that would be cleaned up under a 15 pCi/g criterion. Under
most foreseeable circumstances, we believe the residual hazard would
be acceptably low under Alternative L2.
Alternatives L3 and L4 do not take full advantage of practicable
cleanup. Several thousand acres next to disposal sites would require
land-use controls. The costs saved are small in relation to total
costs and do not warrant the higher risks that would remain.
We believe it is neither practical nor worthwhile to cleanup
contaminated areas to surface concentrations below 5 pCi/g.
Identifying contaminated surface soils with radium concentrations less
than 5 pCi/g is difficult and expensive. Complex measurement
techniques are required. Increasingly large land areas would need to
be cleaned up. Doing this would provide very little gain in health
protection, because such slightly contaminated soils are usually thin
layers containing small amounts of tailings that pose insignificant
risks.
For offsite properties, the cleanup costs vary little with the
choice -of numerical cleanup standards because tailings typically have
been used with little mixing with other materials. If a standard based
on Alternative L2 for nearby land is rigidly applied, up to $39 million
may be spent in cleaning up these properties. However, many of these
contaminated offsite properties present little existing or potential
hazard because of the small amount of tailings involved, or because of
their location. In Chapter 7 we considered applying the land cleanup
standard for offsite locations only when appropriate threshold
conditions are exceeded. This was projected to save $24 million
without sacrificing protection of people. We therefore selected this
alternative.
Radiation Hazards not Associated with Radium-226
Radium-226 concentrations in the residual tailings may not
adequately measure the radiation hazard in all cases. The possibility
that this could happen at one or more inactive processing sites cannot
be ruled out, but we do not know of a site where this has happened.
Should such circumstances occur, our supplemental standards (see below)
will require the implementing agencies to reduce residual radioactivity
to levels that are as low as may reasonably be achieved.
8.4 Supplemental Standards
In view of the varied conditions and our limited remedial action
experience with tailings, these standards must be flexible. We believe
our standards are the most protective that can justified for general
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application at all the inactive sites. However, the standards could be
too strict in any specific application if the costs or undesirable side
effects of the remedial actions were grossly disproportionate to the
benefits of full compliance. We anticipate that such circumstances
might occur. Therefore, we prefer to provide criteria under which the
implementers may perform alternate remedial actions that they believe
come as close to meeting the disposal and cleanup standards as is
reasonably achievable under the pertinent circumstances.
When the agencies implementing the disposal, land, and building
cleanup standards for uranium mill tailings determine that one or more
of the following criteria apply at a specific location, then the
agencies may apply supplemental standards. For this we list the
following criteria:
(1) Public health or safety would be unavoidably
endangered by otherwise required remedial actions.
(2) Remedial actions would cause significant
environmental damage, in comparison to the
environmental and health benefits that would result
from satisfying the standard.
(3) The costs of land cleanup would be unreasonably high
relative to the long-term benefits, and the residual
radioactive materials do not pose a clear present or
future hazard.
(4) The remedial action costs for buildings are clearly
unreasonably high relative to the benefits.
(5) Radionuclides other than those upon which the'
standards are based (i.e., radium-226 and its decay
products) cause significant hazards.
(6) There are no known remedial actions available.
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Chapter 9: IMPLEMENTATION
9.1 Standards Implementation Process
Administrative Process
The Act (PL 95-604) requires that the Secretary of Energy
implement these standards for cleanup and disposal of uranium mill
tailings from inactive processing sites. The Secretary or a designated
party will select and perform remedial actions for designated
processing sites with the participation of any State that shares the
cost. The Act also requires that NRC concur in selecting and
performing remedial actions, and affected Indian tribes and the
Secretary of the Interior be consulted as appropriate. Finally, the
Act prescribes how the Federal Government and the States will share the
costs of the remedial actions.
Implementing the Disposal Standards
The standards will be implemented through analyses that show the
selected control method provides a reasonable assurance of satisfying
the requirements of the standards for the required period of time.
These analyses will include the physical properties of the site and the
planned control system, and the long-term effects of natural
processes. Computational models, theories, and expert judgment will be
major tools in assessing whether a proposed control system will satisfy
both short and long-term requirements. The results of such assessments
will necessarily be uncertain. The standard, therefore, requires only
"reasonable assurance" of compliance with its specifications. The
implementers ultimately must make the judgment whether or not a control
system will meet the requirements.
Post-remediation monitoring can determine whether the radon
emission standards are satisfied and that the control system is
performing as expected. Demonstrating compliance with long-term
standards cannot reasonably be done by monitoring only, however.
Compliance must instead depend on the adequacy of the design and
implementation of the control system. In any case, exhaustive
measurements are not appropriate because the consequences of small
deviations from the standards are minor.
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Implementing the Standards for Cleanup of Buildings and Open Land
The DOE will make radiation surveys of open lands and buildings in
areas that are likely to have tailings and determine whether remedial
actions are required. After remedial actions, compliance with the
standards will have to be verified. DOE, working with NRC and the
participating State, will develop radiological survey, sampling, and
measurement procedures to determine necessary cleanup actions and the
results of the cleanup. We have published elsewhere a discussion of
the general requirements for an adequate land cleanup survey (EPA78c).
The choice of verification procedures is important to assure both
effective and economic implementation of the standards. In view of_
this, we considered providing more details for the implementation as
part of our rulemaking. But, so as to give more flexibility to the
implementers, we chose not to do so. We believe this is warranted
because conditions at the processing sites vary widely and are
incompletely known. Our intent is also to avoid the unproductive use
of resources that could result if implementation guidance were
interpreted so strictly that complying in all situations would be
unreasonably burdensome.
The purpose of cleanup standards is to protect public health and
the environment. The standards should provide adequate protection if
implemented using search and verification procedures of reasonable cost
and technical specifications. Since, for example, we intend the
building cleanup standards to protect people, measurements in locations
such as crawl spaces and furnace rooms are inappropriate for
determining compliance. Compliance decisions should be based on
radiation levels in occupiable parts of the building. The standards
for cleaning up land surfaces limit exposures of people to gamma
radiation and to radon decay products in future building. In most
circumstances, failure to detect a few square feet of land contaminated
by tailings would be insignificant. Similarly, reasonableness must
prevail in determing where and how deeply to search for tailings
beneath the surface on open land. It would be unreasonable to require
proof that all possible buried tailings had been found. In all
applications of our proposed cleanup standards, search and verification
procedures that provide reasonable assurance of compliance with the
numerical requirements will be adequate. Necessary measurements should
be performed within the accuracy of available field and laboratory
instruments used in conjunction with reasonable survey and sampling
procedures.
9.2 Effects of Implementing the Standards
Health
The Proposed Standards and Alternatives A, B, and C reduce average
radon emissions from the tailings piles by about 99.6, 99.6, 96, and 80
percent, respectively. By extrapolating the current projected rate of
lung cancer deaths due to radon from the piles over the first 1,000
years, we estimate that applying the standards will prevent 2,000,
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2,000, 1,900, and 1,500 premature lung cancer deaths, respectively, and
will prevent additional deaths thereafter in similar varying degree,
but for different lengths of time. Alternatives D and E do not
explicitly require reduction of radon releases, but we estimate radon
reductions implicit to their implementation would prevent a total of
800 and 600 premature deaths, respectively. Under the Proposed
Standards and Alternative A, people living very near tailings piles
during the next several thousand years would bear a risk of premature
death from lung cancer of about 1 chance in 10,000; under Alternative B
about 1 in 1,000; under Alternative C about 6 in 1,000; under
Alternatives D and E the risk would be reduced by at most 50 percent
for a few hundred years, to several chances in 100.
The misuse of tailings in constructing buildings poses the
greatest hazard to human health associated with tailings piles. Under
the Proposed Standards and Alternatives A and B, we believe the
possibility of unauthorized removal of the tailings will be unlikely
for many thousands of years. Alternative C would provide such
protection for at least a few thousand years. Under Alternatives D and
E there would be no substantial physical barrier to human access to the
tailings; misuse is much more likely after the few hundred years
institutional controls are required to be maintained for these
alternatives.
We estimate that performing remedial actions to meet the Proposed
Standard could result in 3 accidental deaths among workers and the
public, and 4, 2, 1, 1, and 1 accidental deaths under Alternatives A-E,
respectively.
After remedial actions are completed on eligible buildings,
building occupants will be subject to premature death from residual
tailings at a maximum risk of about 1 percent under Alternatives Bl,
B2, and B3, and 5 percent under Alternative B4. The number of
premature deaths avoided by the remedial actions will be approximately
65, 60, 65 and 55, under Alternatives B1-B4, respectively.
After completing remedial actions to eligible land, residual
radioactive materials will give an individual a maximum risk of about 2
in 100 under Alternatives LI and L2; 6 in 100 under Alternatives L3;
and 10 in 100 under Alternative L4. The dose to persons exposed
continuously to gamma radiation would be about 26, 60, 193, and 385
mrem/y, respectively, under Alternatives L1-L4.
About 6500 offsite locations where tailings have been used could
be cleaned up under any of the Alternatives. This number will be
reduced to about half, however, if remedial actions are performed only
where there is a significant quantity of tailings in a location that
poses a clear present or future hazard.
Environmental
Under the Proposed Standards and Alternatives A, B, and C, the
integrity of all 24 tailings piles would be maintained for at least
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1,000 years, and probably much longer; neither floods nor erosion
should spread the tailings for many thousands of years in most cases.
Under Alternative D a small number of piles could be damaged by floods
during the first 1,000 years and some erosional spreading occur
thereafter. Under Alternative E, severe flood damage during this
period is likely at several sites, and erosional spreading may occur at
most sites after a few hundred years.
Radon gas releases from tailings piles under the Proposed
Standards and Alternative A would be essentially the same as from
ordinary land for thousands of years. Releases well above normal
levelss but well below current emission levels, should prevail for
thousands of years at most piles under Alternatives B and C. Under
Alternatives D and E, radon releases from the piles would be only
slightly reduced from current levels. The environmental effects of
such releases are negligible. (Effects on human health are discussed
in the previous section).
It is not clear whether the current condition of tailings piles
poses a significant threat to water quality. Under the Proposed
Standards and Alternative A, however, all surface and ground water
supplies will be assured protection for at least 1,000 years from
significant degradation that results from post-remediation releases of
harmful substances from tailings piles. Under Alternatives B and C,
any significant potential water pollution should be avoided to the
extent the implementing agencies determine reasonable. Under
Alternative D, harm from any water polluted by tailings would be
avoided for 100 years by either passive (preventive) or active
(treatment or substitution) methods. Alternative E would not avoid any
potential water pollution.
Contaminated land will be subjected to scraping and digging by the
cleanup operations. Generally, these operations will occur immediately
adjacent to the piles; offsite areas where tailings have been deliber-
ately used also will be affected. We estimate that 2,700, 1,900, 900,
and 250 acres near the piles would be cleaned up under Alternatives
L1-L4, respectively. Approximately 6,500 offsite locations would be
cleaned up under the Alternatives L1-L4; about half this number could
be exempted under the Supplemental Standards (see Section 8.4).
Much of the contaminated land near the piles already has been
disturbed during mill operations. Virtually all the offsite locations
have been disturbed to some degree. It is likely, however, that some
higher grade soils will be removed from undisturbed areas, perhaps with
long-term (a few decades) detrimental local environmental effects.
Control methods and the means of minimizing undesirable.environmental
effects will have to be considered for eaqh site. The general
ecological effects of land cleanup and restoration operations are
examined in detail in a separata EPA report (EPA78c).
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Disposal operations may require large quantities of earth, clay,
and rock for covering the tailings, depending on the control method.
Most of these materials need not be high quality or suitable for
agricultural or other priority uses. Some waste materials may be
available, such as existing mine wastes. We expect that the Proposed
Standards, Alternative A, and Alternative B will make the greatest
demand for such materials, Alternative C a moderate demand, and
Alternatives D and E the least.
Economic
Estimating the total control and stabilization costs for all the
tailings piles eligible under PL 95-604 is difficult, primarily because
methods will be chosen specifically for each site. The assumptions we
made (see Chapter 6) minimize the uncertainty in relative costs of the
control standards we considered. We estimated the total tailings pile
control costs for meeting the requirements of the Proposed Standards
and Alternatives A-E as $372, $448, $294, $322 or $297, $250, and $232
million, respectively, in 1981 dollars.
We estimated the cleanup costs for open land near tailings piles
as $21, $14, $7, and $2 million (1981 dollars) for satisfying
Alternatives L1-L4, respectively. Cleanup costs for offsite properties
would be about $39 million (1981 dollars) under any of the standards we
considered. If only contaminated offsite locations that pose a clear
present or future hazard are cleaned up, the cost would be $15 million
(1981).
To satisfy Alternatives B1-B4. we estimated the cleanup costs for
buildings to be $11.5, $8.5, $9, and $9.5 million, respectively. Here,
however, we assumed somewhat different remedial methods for each
alternative in order to explore the effects on the costs and benefits.
Therefore, the relative cost estimates under each alternative may not
be precise, but the range of estimates is a likely indicator of actual
program costs under any of the alternatives.
The highest and lowest total program cost estimates obtainable
under the standards are $540 million and $260 million, respectively.
The costs of satisfying EPA's preferred standards (see Chapter 8)
correspond approximately to those of control Alternative B and cleanup
Alternatives L2 and B2 (assuming that Alternative L2 is applied only
where there is a clear present or future hazard), or about $330
million. The Federal government will assume a 90 percent share, and
the government of any State in which an inactive processing site is
located will pay 10 percent. We expect the expenditures will be spread
over the seven-year authorization of the program. Most of these
expeditures will occur in the regions where the tailings are located.
Their local significance will depend on the amount expended, the size
of the local economy, and the availability of necessary equipment and
labor.
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Cleaned up land and buildings might be made available for use as a
result of the cleanup program. On the other hand, moving tailings to a
new location removes the new site from other potential uses.
We estimate that the remedial program could result in net economic
benefits of decreased unemployment and increased business activity for
the regions where the piles are located. We expect little or no
perceptible national impact because the maximum average annual
expenditures over the seven years of this program will be small
compared to the annual Federal budget (less than 0.01 percent of the
1981 budget outlays), the annual Gross National Product (less than
0.003 percent of the 1981 GNP), and the construction industry (less
than 0.03 percent of 1981 value of structures put in place).
144
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EPA-R3-73-033, USEPA, Washington, D.C., 1972.
152
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REFERENCES (Continued)
NAS76 National Academy of Sciences, Health Effects of Alpha-
Emitting Particles in the Respiratory Tract, Report of Ad Hoc
Committee on "Hot Particles" of the Advisory Committee on the
Biological Effects of Ionizing Radiations, EPA Contract No.
68-01-2230, EPA 520/4-76-013, USEPA, Washington, D.C., October
1976.
NAS77 National Academy of Sciences, Drinking Mater and Health, Part
If Chap. 1-5, NAS Advisory Center on Toxicology, Assembly of
Life Sciences, Washington, B.C., 1977.
Ne7S Nelson J.D. and Shepherd T.A., Evaluation of Long-Term
Stability of Uranium Tailing Disposal Alternatives, Civil
Engineering Department, Colorado State University, prepared
for Argonne National Laboratory, April 1978.
NP76 National Council on—Radiation—Protection and Measurements,
Environmental Radiation Measurements, NCRP Report No. 50,
Washington, D.C., December 1976.
NRC79 Nuclear Regulatory Commission, Draft Generic Environmental
Impact Statement on Uranium Milling, Volume II, NUREG-0511,
USNRC, Washington, D.C., 1979.
NRC80 Nuclear Regulatory Commission, Final Generic Environmental
Impact Statement on Uranium Milling, NUREG-0706, USNRC,
Washington, D.C., September 1980.
NS78 National Safety Council, Accident Facts, 444 N. Michigan
Avenue, Chicago, Illinois.
Oa72 Oakley D.T., Natural Radiation Exposure in the United
States, ORP/SID 72-1, USEPA, Washington, D.C., 1972.
Pea70 Correspondence between Paul J. Peterson, Acting Surgeon
General, PHS, DHEW, and Dr. R.L. Cleere, Executive Director,
Colorado State Department of Health, July 1970.
Peb77 Peterson B.H., "Background Working Levels and the Remedial
Action Guidelines," in: Proceedings of a Radon Workshop,
Department of Energy Report No. HASL-325, July 1977.
Pr74 Press F. and Siever R., Earth, W.H. Freeman and Company, San
Francisco, 1974.
Pu77 Purtyman W.D., Wienke C.L. and Dreesen D.R., Geology and
Hydrology in the Vicinity of the Inactive Uranium Mill
Tailings Pile, Ambrosia Lake, New Mexico, LA-6839-MS, Los
Alamos Scientific Laboratory; New Mexico, 1977.
153
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REFERENCES (Continued)
Ra78 Rahn P.H. and Mabes D.L., "Seepage from Uranium Tailings Ponds
and its Impact on Ground Water," in: Proceedings of the
Seminar on Management, Stabilization, and Environmental Impact
of Uranium Mill Tailings, the OECD Nuclear Energy Agency,
July 1978.
Ro77 Rochlin G.I., "Long-term Waste Management: Criteria or
Standards?" in: Proceedings of a Workshop on Issues
Pertinent to the Development of Environmental Protection
Criteria for Radioactive Wastes, EPA Report ORP/CSD-77-1,
USEPA, Washington, D.C., 1977.
RPC80 Radiation Policy Council, Report of the Task Force on Radon
in Structures, RP-80-002, Radiation Policy Council,
Washington, D.C., August 1980.
Ru81 Rudnick S.N., Hinds W.C., Maher E.G., Price J.M., Fujimoto K.,
Gu F. and First M.W., Effect of Indoor Air Circulation
systems on Radon Decay Product Concentration, Draft Final
Report to U.S. EPA under Contract #68-01-6029, November 1981.
Sca74 Schiager K.J., "Analysis of Radiation Exposures on or Near
Uranium Mill Tailings Piles," in: Radiation Data and
Reports, pp.411-425, July 1974.
Sca77 Schiager K.J., "Radwaste Radium-Radon Risk," in: Proceedings
of a Workshop on Policy and Technical Issues Pertinent to the
Development of Environmental Protection Criteria for
Radioactive Wastes, EPA Report ORP/CSD-77-2, USEPA,
Washington, D.C., 1977.
ScbSO Schwendiman L.C., Sehmel G.A., Horst T.W., Thomas C.W. and
Perkins R.W., A Field and Modeling Study of Windblown
Particles from a Uranium Mill Tailings Pile, NUREG/CR-14007,
Battelle-Pacific Northwest Laboratory, Richland, Washington,
June 1980.
Se75 Sears M.B., et al., Correlation of Radioactive Waste
Treatment Costs and the Environmental Impact of Waste
Effluents in the Nuclear Fuel Cycle for Use in Establishing
'as Low as Practicable' Guides - Milling of Uranium Ores,
Report ORNL-TM-4903, Two Volumes, Oak Ridge National
Laboratory, Tennessee, 1975.
SE80 SCS Engineers, Residual Actions at Uncontrolled Hazardous
Waste Sites, Covington, Kentucky, 1980.
Sh78 Shreve J.D. Jr., in: Proceedings of the Seminar on Manage-
ment, Stabilization and Environmental Impact of Uranium Mill
Tailings, the OECD Nuclear Energy Agency, p.350, July 1978.
154
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REFERENCES (Continued)
Sw76 Swift J.J., Hardin J.M., Calley H.W., Potential Radiological
Impact of Airborne Releases and Direct Gamma Radiation to
Individuals Living Near Inactive Uranium Mill Tailings Piles,
EPA-520/1-76-001, Office of Radiation Programs, USEPA,
Washington, D.C, 1976.
Sw81 Swift J.J., Health Risks to Distant Populations from Uranium
Mill Tailings Radon, Technical Note ORP/TAD-80-1, Office of
Radiation Programs, USEPA, Washington, D.C., 1981.
ThaSO Correspondence between John G. Themelis, USDOE, Grand
Junction, Colorado, and Kenneth R. Baker, USDOE, January 23,
1980.
ThbSl Thode E.F. and Dreesen D.R., "Technico-Economic Analysis of
Uranium Mill Tailings Conditioning Alternatives," in:
Proceedings of the 4th Symposium on Uranium Mill Tailings
Management, Fort Collins, Colorado, October 1981.
UI80 University of Idaho, Overview of Ground Water Contamination
Associated with Six Operating Uranium Mills in the United
States, College of Mines and Mineral Resources, University of
Idaho, 1980.
UN77 United Nations Scientific Committee on the Effects of Atomic
Radiation, Sources and Effects of Ionizing Radiation, Report
to the General Assembly, U.N. Publication E. 77.IX.1, United
Nations, NY., 1977.
Ve78 Venugopal B. and Luckey T.D., Metal Toxicity in Mammals,
Volume 2, Chemical Toxicity of Metals and Metaloids, Plenum
Press, New York, 1978.
Wi78 Windham S.T., Savage E.D. and Phillips C.R., The Effects of
Home Ventilation Systems on Indoor Radon-Radon Daughter
Levels, EPA 520/5-77-011, USEPA, Montgomery, Alabama, 1978.
Yo75 Young K., Geology: The Paradox of Earth and Man, Houghton-
Mifflin, Boston, 1975.
155
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GLOSSARY OF TERMS AND ABBREVIATIONS
-------
GLOSSARY OF TERMS AND ABBREVIATIONS
ABC
Atomic Energy Commission (discontinued with formation of ERDA and
NRC on January 19, 1975.)
alpha particle
A positively charged particle having the mass and charge of a
helium nucleus; i.e., two protons and two neutrons.
aquifer
A water-bearing layer of permeable rock or soil. A subsurface
formation containing sufficient saturated permeable material to
yield significant quantities of water.
Curie (Ci)
A special unit of radioactivity equal to 37 billion nuclear
transformations (e.g., decays of radium into radon) per second.
decay
The spontaneous nuclear (radioactive) transformation of one
nuclide into another or into a different energy state of the same
nuclide through a process which results in the emission of
radiation.
decay chain
The sequence of radioactive transformations from one nuclide to
other nuclides eventually ending in a nonradioactive nuclide.
decay products
The subsequent nuclides formed by the radioactive transformation
of a given nuclide.
DOE
U.S. Department of Energy. Established by Executive Order in
October 1977. Comprises the following former agencies: Energy
Research and Development Administration, Federal Energy
Administration, Federal Power Commission, and parts of the
Department of Interior.
159
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dose
The energy imparted to matter by ionizing radiation per unit mass
of irradiated material at a specific location. A unit of absorbed
dose is the rad. A general term indicating the amount of energy
absorbed from incident radiation by a specified mass.
EPA
U.S. Environmental Protection Agency.
emission rate
The amount of a substance emitted from a source over a defined
period of time.
erosion
The process of wearing away the land surface by the action of
wind, water, glaciers, and other geological agents.
9
grams
gamma radiation
Electromagnetic energy (photon) emitted as a result of a nuclear
transition.
GJO
Grand Junction Office, Department of Energy.
ground water
Water in the zone of saturation beneath the land surface.
half-life
A half-life is the time it takes for a given quantity of a
radioactive isotope to decay to half of that quantity.
ICRP
International Commission on Radiological Protection
m
1. meter
2. as a prefix, milli. See "milli."
milli
Prefix indicating 1/1,000 or 10~3 (abbreviated "m").
NRC
U.S. Nuclear Regulatory Commission (former regulatory part of AEC).
nuclide
An atomic nucleus specifiad by its atomic mass number, atomic
number, and energy state. A radionuclide is a radioactive nuclide.
P
Pico. Prefix indicating 1/1,000,000,000,000 or 10~12.
160
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person-rem
A unit of population dose equivalent. The population dose
equivalent is equal to the sum of the individual dose equivalents
(to the same target tissue) for all members of the population
considered.
pH
A measure of the hydrogen ion concentration in aqueous solutions.
Acidic solutions have a pH less than 7. Basic solutions have a pH
greater than 7.
ppm
Parts per million.
rad
A special unit of absorbed dose. It is the amount of energy
imparted per unit mass of irradiated material at the place of
interest by ionizing radiations (one rad equals 0.01 Joules per
kilogram).
rem
A special unit of dose equivalent to a specific organ or tissue or
to the whole body. It is obtained by multiplying the absorbed
dose in rads by weighting factors chosen to provide nominal
biological effect equivalence for different ionizing radiation
(e.g., neutrons, alpha particles, gamma radiation, etc.)
Roentgen (R)
A special unit of radiation exposure to air. It is the measure of
electrical charge per unit mass produced in air by X or gamma
radiation. One roentgen is equal to 2.58 x 10~^ coulomb per
kilogram of air. [Note: For X or gamma radiation, the numerical
value of absorbed dose (rad) in tissue is generally of the same
magnitude as the numerical value of exposure (R)].
Working Level (WL)
A special unit of exposure rate to short-lived radon decay
products in air. The unit was originally developed to measure
radon decay product exposure to workers in uranium mines. The
exposure rate is the total alpha particle energy which would be
released by the combined radon decay products per unit volume of
air. One Working Level is equal to 130,000 million electron volts
of alpha-particle energy per liter of air.
Radon decay product exposure is the Working Level Month (WLM). It
is obtained by multiplying the exposure rate by the time spent at
that exposure rate. One WLM is the exposure that would result
from a 170-hour period (a working month) at an exposure rate of
1 WL.
161
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APPENDIX A
STANDARDS FOR REMEDIAL ACTIONS AT
INACTIVE URANIUM PROCESSING SITES
-------
Appendix A: STANDARDS FOR REMEDIAL ACTIONS AT INACTIVE
URANIUM PROCESSING SITES
A new Part 192 is added to 40 CFR Chapter I, Subchapter F, as
follows:
Part 192 - HEALTH AND ENVIRONMENTAL PROTECTION STANDARDS FOR
URANIUM MILL TAILINGS
Subpart A — Standards for the Control of Residual Radioactive
Materials from Inactive Uranium Processing Sites
Sec.
192.00 Applicability
192.01 Definitions
192.02 Standards
Subpart B — Standards for Cleanup of Land and Buildings
Contaminated with Residual Radioactive Materials
from Inactive Uranium Processing Sites
192.10 Applicability
192.11 Definitions
192.12 Standards
Subpart C — Implementation
192.20 Guidance for Implementation
192.21 Criteria for Applying Supplemental Standards
192.22 Supplemental Standards
192.23 Effective Date
A-3
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AUTHORITY: Section 275 of the Atomic Energy Act of 1954, 42 U.S.C.
2022, as added by the Uranium Mill Tailings Radiation Control Act of
1978, PL 95-604.
Subpart A — Standards for the Control of Residual Radioactive
Materials from Inactive Uranium Processing Sites
192.00 Applicability
This subpart applies to the control of residual radioactive
material at designated processing or depository sites under Section
108 of the Uranium Mill Tailings Radiation Control Act of 1978
(henceforth designated "the Act"), and to restoration of such sites
following any use of subsurface minerals under Section 104(h) of the
Act.
192.01 Definitions
(a) Unless otherwise indicated in this subpart, all terms shall
have the same meaning as in Title I of the Act.
(b) Remedial action means any action performed under Section
108 of the Act.
(c) Control means any remedial action intended to stabilize,
inhibit future misuse of, or reduce emissions or effluents from
residual radioactive materials.
(d) Disposal site means the region within the smallest
perimeter of residual radioactive material (excluding cover
materials) following completion of control activities.
A-4
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(e) Depository site means a disposal site (other than a
processing site) selected under Section 104(b) or 105(b) of the Act.
(f) Curie (Ci) means the amount of radioactive material that
produces 37 billion nuclear transformation per second. One
-12
picocurie (pCi) =10 Ci.
192.02 Standards
*
Control shall be designed to:
(a) be effective for up to one thousand years, to the extent
reasonably achievable, and, in any case, for at, least 200 years,
and,
(b) provide reasonable assurance that releases of radon-222
from residual radioactive material to the atmosphere will not:
^•&
(1) exceed an average release rate of 20 picocuries per
square meter per second, or
(2) increase the annual average concentration of radon-222
in air at or above any location outside the disposal site by more
than one-half picocurie per liter.
* Because the standard applies to design, monitoring after disposal
is not required to demonstrate compliance.
** This average shall apply over the entire surface of the disposal
site and over at least a one-year period. Radon will come from both
residual radioactive materials and from materials covering them.
Radon emissions from the covering materials should be estimated as
part of developing a remedial action plan for each site. The
standard, however, applies only to emissions from residual
radioactive materials to the atmosphere.
A-5
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Subpart B — Standards for Cleanup of Land and Buildings
Contaminated with Residual Radioactive Materials
from Inactive Uranium Processing Sites
192.10 Applicability
This subpart applies to land and buildings that are part of any
processing site designated by the Secretary of Energy under Section
102 of the Act. Section 101 of the Act, states, in part, that
"processing site" means —
(a) any site, including the mill, containing residual
radioactive materials at which all or substantially all of the
uranium was produced for sale to any Federal agency prior to January
1, 1971 under a contract with any Federal agency, except in the case
of a site at or near Slick Rock, Colorado, unless —
(1) such site was owned or controlled as of January 1,
1978, or is thereafter owned or controlled, by any Federal agency,
or
(2) a license (issued by the (Nuclear Regulatory)
Commission or its predecessor agency under the Atomic Energy Act of
1954 or by a State as permitted under Section 274 of such Act) for
the production at
site of any uranium or thorium product derived from ores is in
effect on January 1, 1978, or is issued or renewed after such date;
and
A-6
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(b) any other real property or improvement thereon which —
(1) is in the vicinity of such site, and
(2) is determined by the Secretary, in consultation with
the Commission, to be contaminated with residual radioactive
materials derived from such site.
192.11 Definitions
(a) Unless otherwise indicated in this subpart, all terms shall
have the same meaning as defined in Title I of the Act or in Subpart
A.
(b) Land means any surface or subsurface land that is not part
of a disposal site and is not covered by an occupiable building.
(c) Working Level (WL) means any combination of short-lived
radon decay products in one liter of air that will result in the
ultimate emission of alpha particles with a total energy of 130
billion electron volts.
(d) Soil means all unconsolidated materials normally found on
j
or near the surface of the earth including, but not limited to,
silts, clays, sands, gravel, and small rocks.
192.12 Standards
Remedial actions shall be conducted so as to provide reasonable
assurance that, as a result of residual radioactive materials from
any designated processing site:
A-7
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(a) the concentration of radium-226 in land averaged over any
area of 100 square meters shall not exceed the background level by
more than —
(1) 5 pCi/g, averaged over the first 15 cm of soil below
the surface, and
(2) 15 pCi/g, averaged over 15 cm thick layers of soil
more than 15 cm below the surface.
(b) in any occupied or habitable building —
(1) the objective of remedial action shall be, and
reasonable effort shall be made to achieve, an annual average (or
equivalent) radon decay product concentration (including background)
not to exceed 0.02 WL. In any case, the radon decay product
concentration (including background) shall not exceed 0.03 WL, and
(2). the level of gamma radiation shall not exceed the
background level by more than 20 microroentgens per hour.
Subpart C — Implementation
192.20 Guidance for Implementation
Section 108 of the Act requires the Secretary of Energy to
select and perform remedial actions with the concurrence of the
Nuclear Regulatory Commission and the full participation of any
State that pays part of the cost, and in consultation, as
appropriate, with affected Indian Tribes and the Secretary of the
Interior. These parties, in their respective roles under Section
108, are referred to hereafter as "the implementing agencies."
A-8
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The implementing agencies shall establish methods and
procedures to provide "reasonable assurance" that the provisions of
Subparts A and B are satisfied. This should be done as appropriate
through use of analytic models and site-specific analyses, in the
case of Subpart A, and for Subpart B through measurements performed
within the accuracy of currently available types of field and
laboratory instruments in conjunction with reasonable survey and
sampling procedures. These methods and procedures may be varied to
suit conditions at specific sites. In particular:
(a) The purpose of Subpart A is to provide for long-term
stabilization and isolation in order to inhibit misuse and spreading
of residual radioactive materials, control releases of radon to air,
and protect water. Subpart A may be implemented through analysis of
the physical properties of the site and the control system and
projection of the effects of natural processes over time. Events
and processes that could significantly affect the average radon
release rate from the entire disposal site should be considered.
Phenomena that are localized or temporary, such as local cracking or
burrowing of rodents, need to be taken into account only if their
cumulative effect would be significant in determining compliance
with the standard. Computational models, theories, and prevalent
expert judgment may be used to decide that a control system design
will satisfy the standard. The numerical range provided in the
standard for the longevity of the effectiveness of the control of
residual radioactive materials allows for consideration of the
various factors affecting the longevity of control and stabilization
A-9
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methods and their costs. These factors have different levels of
predictability and may vary for the different sites.
Protection of water should be considered in the analysis for
reasonable assurance of compliance with the provisions of
Section 192.02. Protection of water should be considered on a
case-specific basis, drawing on hydrological and geochemical surveys
and all other relevant data. The hydrologic and geologic assessment
to be conducted at each site should include a monitoring program
sufficient to establish background groundwater quality through one
or more upgradient wells, and identify the presence and movement of
plumes associated with the tailings piles.
If contaminants have been released from a tailings pile, an
assessment of the location of the contaminants and the rate and
direction of movement of contaminated ground water, as well as its
relative contamination, should be made. In addition, the assessment
should identify the attenuative capacity of the unsaturated and
saturated zone to determine the extent of plume movement. Judgments
on the possible need for remedial or protective actions for
groundwater aquifers should be guided by relevant considerations
described in EPA's hazardous waste management system (47 FR 32274,
July 26, 1982) and by relevant State and Federal Water Quality
Criteria for anticipated or existing uses of water over the term of
the stabilization. The decision on whether to institute remedial
action, what specific action to take, and to what levels an aquifer
should be protected or restored should be made on a case-by-case
basis taking into account such factors as technical feasibility of
A-10
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improving the aquifer in its hydrogeologic setting, the cost of
applicable restorative or protective programs, the present and
future value of the aquifer as a water resource, the availability of
alternative water supplies, and the degree to which human exposure
is likely to occur.
(b) Compliance with Subpart B, to the extent practical, should
be demonstrated through radiation surveys. Such surveys may, if
appropriate, be restricted to locations likely to contain residual
radioactive materials. These surveys should be designed to provide
for compliance averaged over limited areas rather than point-by-
point compliance with the standards. In most cases, measurement of
gamma radiation exposure rates above and below the land surface can
be used to show compliance with Section 192.12(a). Protocols for
making such measurements should be based on realistic radium
distributions near the surface rather than extremes rarely
encountered.
In Section 192.12(a), "background level" refers to the native
radium concentration in soil. Since this may not be determinable in
the presence of contamination by residual radioactive materials, a
surrogate "background level" may be established by simple direct or
indirect (e.g., gamma radiation) measurements performed nearby but
outside of the contaminated location.
Compliance with Section 192.12(b) may be demonstrated by
methods that the Department of Energy has approved for use under PL
92-314 (10 CFR 712), or by other methods that the implementing
agencies determine are adequate. Residual radioactive materials
A-ll
-------
should be removed from buildings exceeding 0.03 WL so that future
replacement buildings will not pose a hazard [unless removal is not
practical—see Section 192.21(c)]. However, sealants, filtration,
and ventilation devices may provide reasonable assurance of
reductions from 0.03 WL to below 0.02 WL. In unusual cases, indoor
radiation may exceed the levels specified in Section 192.12(b) due
to sources other than residual radioactive materials. Remedial
actions are not required in order to comply with the standard when
there is reasonable assurance that residual radioactive materials
are not the cause of such an excess.
192.21. Criteria for Applying Supplemental Standards
The implementing agencies may (and in the case of Subsection
(f) shall) apply standards under Section 192.22 in lieu of the
standards of Subparts A or B if they determine that any of the
following circumstances exists:
(a) Remedial actions required to satisfy Subparts A or B would
pose a clear and present risk of injury to workers or to members of
the public, notwithstanding reasonable measures to avoid or reduce
risk.
(b) Remedial actions to satisfy the cleanup standards for land,
Section 192.12(a), or the acquisition of minimum materials required
for control to satisfy Section 192.02(b), would, notwithstanding
reasonable measures to limit damage, directly produce environmental
harm that is clearly excessive compared to the health benefits to
persons living on or near the site, now or in the future. A clear
A-12
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excess of environmental harm is harm that is long-term, manifest,
and grossly disproportionate to health benefits that may reasonably
be anticipated.
(c) The estimated cost of remedial action to satisfy Sec.
192.12(a) at a "vicinity" site (described under Sec. 101(6)(B) of
the Act) is unreasonably high relative to the long-term benefits,
and the residual radioactive materials do not pose a clear present
or future hazard. The likelihood that buildings will be erected or
that people will spend long periods of time at such a vicinity site
should be considered in evaluating this hazard. Remedial action
will generally not be necessary where residual radioactive materials
have been placed semi-permanently in a location where site-specific
factors limit their hazard and from which they are costly or
difficult to remove, or where only minor quantities of residual
radioactive materials are involved. Examples are residual
radioactive materials under hard surface public roads and sidewalks,
around public sewer lines, or in fence post foundations. Supple-
mental standards should not be applied at such sites, however, if
individuals are likely to be exposed for long periods of time to
radiation from such materials at levels above those that would
prevail under Section 192.12(a).
(d) The cost of a remedial action for cleanup of a building
under Sec. 192.12(b) is clearly unreasonably high relative to the
benefits. Factors that should be included in this judgment are the
anticipated period of occupancy, the incremental radiation level
that would be affected by the remedial action, the residual useful
A-13
-------
lifetime of the building, the potential for future construction at
the site, and the applicability of less costly remedial methods than
removal of residual radioactive materials.
(e) There is no known remedial action.
(f) Radionuclides other than radium-226 and its decay products
are present in sufficient quantity and concentration to constitute a
significant radiation hazard from residual radioactive materials.
192.22 Supplemental Standards
Federal agencies implementing Subparts A and B may in lieu
thereof proceed pursuant to this section with respect to generic or
individual situations meeting the eligibility requirements of
Section 192.21.
(a) When one or more of the criteria of Section 192.21(a)
through (e) applies, the implementing agencies shall select and
perform remedial actions that come as close to meeting the otherwise
applicable standard as is reasonable under the circumstances.
(b) When Section 192.21(f) applies, remedial actions shall, in
addition to satisfying the standards of Subparts A and B, reduce
other residual radioactivity to levels that are as low as is
reasonably achievable.
(c) The implementing agencies may make general determinations
concerning remedial actions under this Section that will apply to
all locations with specified characteristics, or they may make a
determination for a specific location. When remedial actions are
proposed under this Section for a specific location, the Department
of Energy shall inform any private owners and occupants of the
A-14
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affected location and solicit their comments. The Department of
Energy shall provide any such comments to the other implementing
agencies. The Department of Energy shall also periodically inform
the Environmental Protection Agency of both general and individual
determinations under the provisions of this section.
192.23 Effective Date
Subparts A, B, and C shall be effective (in 60 days after
promulgation).
A-15
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APPENDIX B
DEVELOPMENT OF COST ESTIMATES
-------
APPENDIX B: DEVELOPMENT OF COST ESTIMATES
CONTENTS
B.I INTRODUCTION B-5
B.2 THE MODEL URANIUM MILL TAILINGS PILES B-5
B.3 UNIT COSTS FOR TAILINGS PILE DISPOSAL B-6
Earth Moving B-6
Transportation on Highways B-6
Rock Cover B-6
Landscaping B-7
Fencing B-7
Maintenance and Inspection B-7
B.4 COST ESTIMATES FOR ALTERNATIVE STANDARDS B-10
Costs for Onsite Control B-10
Costs for Control at New Sites B-10
Costs for Flood Protection Embankments B-13
B.5 TOTAL COST ESTIMATES FOR CONTROLLING TAILINGS B-13
Flood Control Measures B-15
B.6 ADVANCED CONTROL METHODS B-16
Soil Cement B-17
Extraction and Disposal of Hazardous Materials B-18
Long-Term Radon and Hydrology Control B-22
Thermal Stabilization B-24
B.7 REMEDIAL COSTS FOR CLEANUP OF BUILDINGS B-24
Summary of Relevant Data from the Grand Junction Remedial
Action Program B-24
Estimation of Costs B-26
REFERENCES B-30
B-3
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APPENDIX B: DEVELOPMENT OF COST ESTIMATES
CONTENTS—continued
TABLES
B-l Unit Costs for Tasks Associated with Controlling Uranium
Mill Tailings Piles B-8
B-2 Summary of Costs for Onsite Control of Tailings B-ll
B-3 Summary of Costs for Moving and Controlling Tailings
At a New Site B-12
B-4 Estimated Costs of Controlling Uranium Tailings B-14
B-5 Costs of Nitric Acid Leachate Disposal B-20
B-6 Costs of Controlling Residual Tailings B-21
B-7 Cost Estimates for Controlling Uranium Tailings When a Nearby
Open-Pit Mine is Available B-23
B-8 Cost Estimates for Controlling Uranium Tailings When a
Nearby Underground Mine is Available B-25
B-9 Percent of Residences Remaining Above A Selected Radon Decay
Product Level After First Passive Remedial Action B-27
B-10 Estimated Number of Contaminated Buildings Exceeding Selected
Concentrations of Radon Decay Products B-29
B-4
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Appendix B: DEVELOPMENT OF COST ESTIMATES
B.I Introduction
This appendix details the development of cost estimates for:
o The alternative standards for control of tailings
piles discussed in Chapter 6,
o Additional methods of controlling tailings not
considered in Chapter 6, and
o Cleanup of buildings as discussed in Chapter 7.
Costs for the six alternative standards considered in Chapter 6
are in Sections B.2 through B.5; for the additional methods, in Section
B.6; and for building cleanup, in Section B.7.
B.2 The Model Uranium Mill Tailings Piles
All cost estimates are for model tailings piles at a hypothetical
site. Two sizes of model piles are considered, a normal pile and a
small pile. Individual site characteristics are used only for
determining the number of piles to be moved. The characteristics of
the two model piles are:
Normal Pile Small Pile
Volume (cubic yards) 1,100,000 90,000
Area (acres) 53.0 13.6
Height (feet) 13.5 4.3
The model piles are assumed to be square, with vertical sides
before remedial action is undertaken. When remedial action is
completed, the piles are assumed to have the shape of truncated
pyramids with slopes as specified in the alternative standards (see
Table 6-2). All piles are assumed to be located on flat ground.
B-5
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B. 3 Unit Costs for Controlling Tailings Piles
Unit costs, expressed in 1981 dollars, for estimating the costs of
characteristic tasks of controlling tailings piles are presented in
Table B-l. We have attempted to determine unit costs that are typical
of the tasks to be undertaken. Since these costs are used in
developing all costs for controlling tailings piles, we believe they
accurately reflect the differences between the alternative standards.
Differences in costs are a major consideration in the selection of a
standard.
Earth Moving
The unit costs of earth moving are grouped in Table B-l according
to the type of work performed. Earth work costs can vary appreciably
depending on local conditions. For example, soils like hard packed
shale increase the costs of excavation. Local labor costs and
equipment rental costs can also vary.
Earth work costs are taken directly from the Dodge Guide (DG81),
with the exception of the unit costs for clay which are taken from the
AMC comments (AMC81) and are adjusted for inflation.
Transportation for short hauls (up to 2 miles off the highway) are
included under earth work because multipurpose equipment, such as
scrapers, can be used for short-distance hauling as well as for
excavation and spreading. For longer, off-highway hauls, large
off-highway trucks are used. Table B-l provides costs for hauls of
3,500 feet by scraper and hauls of 2 miles by off-highway trucks.
If the cover material is not available on the site, we assume it
must be purchased. The cost of purchasing dirt cover, including
excavation and loading at the supply site and reclamation of the borrow
pit, is !j2.25 per cubic yard. The cost of spreading and compacting the
cover material at the tailings site is $0.60/cubic yard.
Transportation on Highways
The unit cost of transporting earthlike materials on highways is
considerably higher than that for off-highway hauling. We estimate
that the unit cost of hauling these materials is $0.40 per cubic yard-
mile or about $0.30 per ton-mile (DG81). We used these unit costs in
estimating the costs of moving piles because we consider it likely that
10-mile hauls will require use of public roads. On-highway costs would
probably be applicable for hauling dirt, clay, and rock if these
materials are not available nearby.
Rock Cover
Rock cover means a less orderly placement of rocks than is
commonly associated with riprap. Rock cover also implies a less
B-6
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stringent size gradation for the rocks than riprap. Costs for rock
cover are highly variable from site to site. The AMC estimate for
18-inch rock cover is $15.20/yd2 (AMC81) and the NRG estimate is
$6.70/yd2 (NRC80). We used a value between these estimates but
closer to the higher value.
Landscaping
Unit costs for landscaping are taken from the Dodge Guide
(DG81). The difference between the two values given in Table B-l is
the availability of loam or top soil at the disposal site. If loam
must be both purchased and hauled for distances greater than about 2
miles, landscaping costs greatly increase.
Landscaping used to protect 3m-dirt covers is assumed to
support a vegetative cover (mostly grasses) requiring no continuing
maintenance. This factor has been tested at the Monticello site
(Ro81) where some vegetation remains after 20 years with little
maintenance. It is assumed that maintenance, as well as irrigation,
is required for those sites having only 0.5m earth and vegetative
covers.
Fencing
Heavy-duty chain link fencing was selected for this analysis.
The unit cost is $21.60 per foot for an installed 6-foot-high chain
link fence made of 6-gauge aluminum wire (DG81).
Maintenance and Inspection
Maintenance and inspection costs are calculated for:
1. An irrigation system for maintaining vegetation on thin
earth covers.
2. Fencing maintenance.
3. Annual inspections including ground water monitoring,
repair, and revegetation of eroded areas.
The irrigation system design, developed for EPA by PEDCO
Environmental Incorporated (PE81), is for a 40-acre site. It
consists of a 150-hp motor and pump unit, polyethylene piping, and
plastic spray heads. The capital cost of this system is $127,000;
it is assumed that it must be replaced every 20 years. The present
value of capital requirements for 100 years of operation is
$149,000, using a 10 percent discount rate and replacement at 20,
40, 60, and 80 years. Annual costs of operation are $12,000 per
year for maintenance and labor, $9,300 year for electrical power,
and $6,000 per year for overhead, assuming the system is operated 8
hours per week, 8 months per year. The present value of these
B-7
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TABLE B-l. UNIT COSTS FOR TASKS ASSOCIATED WITH CONTROLLING
URANIUM MILL TAILINGS PILES
(1981 Dollars)
Task Cost
Earth work:
Grading:
Move and spread by dozer. $1.07/yd-*
Placing clay liners and covers:
Purchase clay, haul 2 miles, $8.84/yd3
dump, spread, and compact.
Placing earthen cover:
Excavate, haul, spread, and $2.06/yd3
compact-by scrapers for 3,500 feet.
Excavate, load, haul by truck for $2.00/yd3
2 miles off-highway, dump, spread,
and compact.
Excavating pits:
Excavate, haul, and spread by $1.83/yd3
scrapers for 3,500 feet.
Moving tailings:
Excavate by drag line. Load, haul $2.50/yd3
2 miles off highway, spread, and
compact.
Transportation:
Over highway hauling of earth, tailings, $0.40/yd3mile
clay, loam, etc.
Rock cover:
6" thick. S*4.53/yd2
12" thick. $9.07/yd2
18" thick- *13.60/yd2
B-8
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Task
TABLE B-l. UNIT COSTS FOR TASKS ASSOCIATED WITH CONTROLLING
URANIUM MILL TAILINGS PILES (Continued)
(1981 Dollars)
Cost
$3,000/
acre
$7,900/acre
Landscaping:
Loam from site used. Preparation of
area, spread loam 6" thick, and
hydraulically spread lime, fertilizer,
and seed.
Loam purchased with 2-mile haul. Prepare
area, spread loam 6" thick, and hydraulic-
ally spread lime, fertilizer, and seed.
Fencing:
Chain link, 6 feet high, 6 gauge aluminum.
Maintenance and inspection:
Installation and operation of
an irrigation system for 100 years -
present worth at 10% discount rate.
Maintenance of fencing at 1% of capital
cost per year. Present value at 10%
discount rate for 100 years.
Annual inspections including ground
water monitoring and repair and revege-
tation of eroded areas. Present value at
10% discount rate for 100 years.
$21.60/ft
$10,500/acre
0.10 x capital
cost of
fencing
$95,000/site
B-9
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annual costs is $273,000 for 100 years, using a 10 percent discount
rate. Therefore, the total present value of providing irrigation for
100 years is $422,000 for a 40-acre site, or $10,500 per acre. This
translates into a present value of $617,000 for a normal pile and
$153,000 for a small pile.
Maintaining the fence for 100 years is assumed to cost 1 percent
of the installation cost annually. The present value of this
maintenance cost for 100 years at 10 percent discount rate is 0.10 x
fencing capital cost.
The cost for annual inspections at a site is taken directly from
Appendix R of NRC's GEIS (NRC80). For this purpose, we used NRC's
Scenario IV, which requires only limited maintenance. Their inspection
costs are $10,500 annually. This includes $1,000 per year for
maintenance of the fence. Since this cost is already considered, it is
subtracted from the NRG value to give an annual cost of $9,500 per
site. The present value is $95,000 per site using a 10 percent
discount rate for 100 years.
B.4 Cost Estimates for Alternative Standards
We have made 24 cost estimates: for the two model piles for each
of the alternative standards described in Chapter 6 and for controlling
piles onsite and at new sites.
Costs for Onsite Control
Estimated costs for onsite control are summarized in Table B-2.
This table also provides the parameters that affect costs: slopes of
the sides of the piles, cover and rock thickness, and vegetation.
Costs for fencing are included in Alternatives C, D and E. The fencing
is assumed to be placed at a distance of 0.5 km from the edge of the
covered tailings, providing an exclusion zone. The cost of fencing is
about $430,000 per site for all normal piles and about $350,000 per
site for all small piles.
The total area of a tailings pile includes the area over which the
contouring operation will spread the tailings from the initial edge of
the pile. This is determined by the vertical dimension of a pile and
the slope of the sides. This total area is used to estimate costs for
cover materials and vegetation.
Costs for Control at New Sites
Estimated costs for control at new sites are summarized in Table
B-3. The parameters that affect costs are listed as they were for the
onsite options (Table B-2). Costs for fencing are included in Options
C, D, and E.
We have assumed that any new site is excavated so that the
tailings are partially buried, and that the excavated material is
B-10
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TABLE B-2. SUMMARY OF COSTS FOR ONSITE CONTROL OF TAILIN3S
Maximum Cover
Tailings Material
Alterna- Slope
tive
(H:V)
(a)
and
Thickness
Estimated Cost
Rock Cover (1981$ in Millions)
Thickness Vege- Normal Small
(location) tation Pile Pile
EPA
Proposed
Standards
5:1
0.6m clay
3m earth
0.33m (slopes) top
4.9
1.2
Alterna- 8:1 0.6m clay 0.5m (slopes)
tive A 3m earth 0.15m (top)
none
7.0
1.6
Alterna- 4:1 3m earth
tive B
Alterna- 5:1 1m earth
tive C
0.33m (slopes) top
2.9
0.33m (slopes) none 3.0
0.15m (top)
0.7
1.0
Alterna- 3:1 0.5m earth 0.15m (top
tive D and slopes)
none
2.2
0.8
Alterna- 3:1 0.5m earth none
tive E
top
and
slopes
1.7
0.7
Slope is the ratio of horizontal (H) to vertical (V) distance (i.e.
H:V).
^For this alternative the vegetation is maintained for 100 years by
weekly irrigation for eight months each year. Costs also include
maintenance and repair of earth covers.
B-ll
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TABLE B-3. SUMMARY OF COSTS FOR MOVING AND CONTROLLIN3 TAILIN3S
Maximum
Tailings
Alterna- Slope
tive (H:V) (a)
EPA 5:1
Proposed
Standard
Alterna- 8:1
tive A
Cover
Material
and
Thickness
0.6m clay
3m earth
0.6m clay
3m earth
AT A NEW SITE
Rock
Cover
Thickness
(location)
0.33m (slopes)
0.5m (slopes)
0.15m (top)
Estimated Cost
(1981$ in
Vege- Normal
tat ion Pile
top 11.0
none 12.6
Millions)
Small
Pile
1.0
1.2
Alterna- 4:1 3m earth 0.33m (slopes) top
tive B
10.1
Alterna- 5:1 1m earth 0.33m (slopes) none 9.8
tive C 0.15m (top)
0.8
1.3
Alterna- 3:1
tive D
Alterna- 3:1
tive E
0.5m earth 0.15m (top
and slopes)
0. 5m earth none
none 8.9
top and 8.6
slopes (b)
1.2
1.1
(a)
Slope is the ratio of horizontal (H) to vertical (V) distance (i.e. H:V).
For this alternative the vegetation is maintained for 100 years by weekly
irrigation for eight months each year. Costs also include maintenance
and repair of earth covers.
B-12
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used as cover material. We also assume that one of the criteria for
selecting the new control site is its inherent ability to protect
against ground water contamination. Thus, no plastic or clay liner is
required for ground water protection, and no costs are added for
liners. The excavated area is about 110,000 square meters for the
normal pile and about 11,000 square meters for the small pile.
The tailings are excavated, loaded on trucks, hauled to the new
site, and dumped in the excavated pit. They are then spread and
compacted. The tailings are covered with the earth excavated from the
pit and rock, if required for the alternative. The pile is then
landscaped, if required for the alternative. We assume the control
site is 10 miles from the existing site. Considerable reductions in
costs can be realized if a new site can be located close to or adjacent
to the existing site.
The estimated costs for moving a small pile to a new site are less
than the costs for onsite control for the EPA Proposed Standards and
Alternative A (compare costs in Table &-2 with those in Table B-3).
This is because the smaller area to be covered after the pile has been
moved more than offsets the additional excavation and transportation
costs. If the hauling distance is decreased and off-highway trans-
portation becomes feasible for moving to a new site, the costs for
new-site disposal can decrease appreciably.
Costs for Flood Protection Embankments
For some sites, flood protection is needed if the tailings are to
be controlled onsite. Flood protection can be provided by building
embankments around the tailings or on those sides of the tailings
susceptible to flooding. The extent of the embankments around the
piles depends on the topography of the tailings site and the
vulnerability of the site to floods.
For this analysis we assumed that embankments are required around
the tailings pile, that embankments will be built to the same height as
the top of the cover material placed on the tailings, and that riprap
will be placed on the outer face of the embankment. The embankments
are 5 meters wide at the top, have a 2:1 slope on the outer face, are
546 meters (1,780 feet) long on each side, and have riprap placed on
the lower 5 meters of the outer face. The estimated cost of this
embankment is about $1,000,000 and is assumed to be the same for the
normal and small piles.
B.5 Total Cost Estimates for Controlling Tailings
Total costs of controlling tailings for each of the six
alternatives, shown in Table B-4, are derived from the cost estimates
for the generic piles in Tables B-2 and B-3. There are 17 normal-sized
piles and 7 small piles. The number of piles controlled onsite or
moved and controlled at a new site is shown in parentheses in
B-13
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TABLE B-4. ESTIMATED COSTS OF CONTROLLING URANIUM MILL TAILINGS <
7
(in millions of
Onsite Control
Alternative
EPA Proposed
Standard
Alternative A
Alternative B
Alternative Cl 35 (24)
J 35 (24)
35 (24)
35 (24)
Normal
Pile
49 (10)
49 (7)
41 (14)
33 (11)
42 (14)
35 (16)
27 (16)
Small
Pile
6 (5)
8 (5)
5 (7)
5 (5)
7 (7)
6 (7)
5 (7)
Adding
Emb ankmen t s
0
0
6 (6)
1 (1)
6 (6)
3 (3)
0
1981 dollars)
Move and
Control
Normal
Pile
77 (7)
126 (10)
30 (3)
59 (6)
29 (3)
9 (1)
9 (1)
Small
Pile
2 (2)
2 (2)
0
3 (2)
0
0
0
Subtotal
169
221
117
136
120
88
76
Overhead and
Contingencies
85
110
58
68
60
44
38
Total
254
331
175
204
180
132
114
(a'Numbers in parentheses are the number of piles receiving the respective action.
'b'The distinction between Alternatives Cl and C2 is in the number of piles assumed moved rather
than protected in place with embankments.
-------
Table B-4. The number of piles requiring embankments is also indicated.
Factors determining the number of piles to be moved and to be protected
by embankments are more fully discussed later. Embankments are estimated
to cost $1 million in all cases.
Total costs include the costs of remedial actions for contaminated
structures, settling ponds, raffinate pits, mill yards, and other
remnants of mill operations on each site. We assumed this cleanup to be
the same for all alternatives. The estimated cost of $35 million is
based on EPA field experience (HalP) in the 1978 cleanup program
performed at the Shiprock site and has been adjusted for inflation.
All costs are adjusted upward by 50 percent to account for
contractor overhead, contingencies, profit, and engineering. This
adjustment appears reasonable for most operations (DG81). Other costs,
not shown in Table B-4, include the Department of Energy's costs for
management, research and development, inactive tailings site acquisition,
and NEPA (National Environmental Policy Act) actions, all of which are
independent of the selection of a standard. These costs, estimated to be
$118,000,000, have been included in Table 6-4, Chapter 6.
Flood Control Measures
The number of piles moved and the number of piles requiring
embankments for flood protection are important factors in estimating
total costs. Variations in these factors influence total costs for each
alternative.
Two factors determine whether tailings piles need to be moved: the
likelihood of flooding that could cause severe erosion and proximity to
population centers (for Alternative A only). These factors affect 12
sites; 9 are subject to potential flood damage from nearby streams or
rivers, and 9 are near population centers.
EPA Proposed Standard - We estimate that nine piles must be moved to
meet the stability objective for an indefinite period (over 1,000 years)
because the piles are threatened by the flooding of nearby rivers or
streams. No piles would be moved under this alternative because of their
proximity to population centers since we assumed that the 3-meter dirt
cover provides sufficent protection from misuse and radon emissions.
Alternative A - Any piles that are close to population centers must
be moved. Otherwise, the alternative is the same as the EPA Proposed
Standard. This criterion adds three normal-size piles to the total
number moved.
Alternative B - The stability objective of 200 to 1,000 years for
this alternative allows the use of engineering controls for flood
protection, rather than moving the piles to new locations. These
controls are embankments, or dikes, that are built around the tailings
B-15
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pile. For this alternative it is estimated that the stability criterion
can be achieved at six sites with embankments, leaving only three piles
to be moved. No piles would be moved because of nearness to population
centers under this alternative. The three piles to be moved are normal
piles.
Alternative C - The objective of stability for an indefinite period
(over 1,000 years) for this alternative is assumed to require flood
protection for nine piles. However, it is assumed that embankments can
adequately protect as many as six of these piles. Thus, this alternative
requires less stringent flood protection measures than either the EPA
Proposed Standard or Alternative A. Three piles are assumed to be moved
for meeting the least stringent interpretation of Alternative C, and
eight piles are assumed to be moved to meet the most stringent
interpretation. Embankments are assumed to be constructed for the
remaining nine piles believed to be threatened by floods. The high and
low ends of this range are labled Cl and C2, respectively, in Table B-4.
No piles need to be moved because of proximity to population centers
under this alternative.
Alternative D - The 100-year stability objective for this
alternative requires that only one pile be moved. This pile is on a
steeply graded site restricted by a cliff and a river. It probably
cannot be stabilized onsite. It is assumed that embankments would be
required to meet the 100-year criterion at three other sites. This
leaves five piles with no flood protection. No piles would be moved
because of closeness to population centers.
Alternative E - The 100- to 200-year stability objective for this
alternative is based on annual maintenance and inspection requirements.
However, it is assumed these requirements would be inefffective for the
pile on a steeply graded site described under Alternative D. Thus, it is
assumed that one pile would be moved for this alternative. The other
eight sites considered vulnerable to floods would remain vulnerable. The
annual maintenance requirement would probably prevent significant
spreading of the tailings from chronic events. No piles would be moved
because of closeness to population centers or of need to protect water
quality.
B.6 Advanced Control Methods
There are a number of possible alternatives to the control methods
previously considered. One method we have considered in some detail is
placing a soil cement cap over the tailings. Other methods have also
been considered. Most rely on unproven technology and are potentially
very costly. Several methods are discussed in the NRC FGEIS (NRC80).
Two of these methods are summarized here: nitric acid leaching for the
removal of hazardous materials, and burial in a stripmine or underground
mine. These alternatives potentially offer considerable radon
attenuation (to levels below 0.5 pCi/m2s), but the long-term
environmental impact of these methods has not been tested. Thermal
stabilization is another control method that has recently been analyzed.
B-16
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Soil Cement
We have evaluated the use of soil cement as a control measure for
tailings disposal. The specifications of the design are:
a. Sides of piles graded to 3:1 (H:V) slopes;
b. Soil cement caps, 0.15 meter thick, placed on the tops
and sides of the piles;
c. Earth covers, 1 meter thick, placed over the soil
cement caps, on the tops and sides of the piles;
d. Rock, 0.33 meter thick, placed on the slopes of the
piles;
e. Rocky soil, 0.33 meter thick, placed on the tops of
the piles;
f. The tops of the piles planted with indigenous
vegetation.
Available information indicates that uranium tailings can be used
to produce a good quality soil cement. It should be relatively tough
and withstand freezing and thawing. Soil cement, together with the
1-meter earth cover and the 0.33-meter rock cover on the slopes of the
piles should create an effective barrier to human intrusion.
The tops and slopes of the piles must be shaped, fine graded, and
compacted in preparation for placing the soil cement. We assume that
the soil cement can be placed using procedures similar to those used
for highway construction. After the soil cement has been laid down,
graded, and compacted, we assume a thin layer of tar is used as a
curing agent. The tar would, we believe, increase the longevity of the
soil cement, and reduce radon emissions through the soil cement.
There is some doubt that vegetation can be maintained on the top
of the pile without continuing maintenance, because shallow-rooted
vegetation probably cannot survive the droughts typical of the region
of most of the piles, and deep-rooted vegetation cannot be established
in the 1 meter of soil above the soil cement. Therefore, 0.33 meters
of rocky soil is to be placed on top of the 1-meter earth cover before
planting vegetation. If the vegetation fails, much of the fine grained
materials in the top 0.33-meter layer of rocky soil will be eroded
away, leaving a layer of rocks to form a protection cover over the
underlying earth.
The effectiveness of soil cement as a barrier to radon emissions
has not been tested. Nevertheless, our analysis leads us to conclude
that the soil cement, together with the compacted tailings immediately
B-17
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below the soil cement, and the layer of tar, will control emissions to
approximately the same level as a 2-meter earth cover. Therefore, this
design, which includes a 1-meter earth cover over the soil cement,
would provide radon control approximately equal that provided by the
EPA Proposed Standard and Alternatives A and B.
The costs of control are estimated to total $163,000,000,
including moving three piles, providing embankments for six piles,
335,000,000 for cleanup of mill facilities, and a 50 percent increase
for overhead, contingencies, profit and engineering. Therefore, this
control method appears to be equivalent to Alternative B in control
levels achieved and in cost.
Extraction and Control of Hazardous Materials
The technology of nitric acid leaching has not been developed for
extracting radium or nonradiological toxic elements from the tailings
because there has been no need for it.
A nitric acid leaching plant could be developed to remove the
radium and thorium in the tailings. The cost of such chemical
treatment of tailings is, as yet, undetermined, but could be expected
to be as expensive as the original milling process, excluding ore
grinding.
It would require the construction and operation of a nitric acid
leaching mill, a means of disposing of the concentrated nitric acid
leachate, and control of the residual tailings. Since this technique
is expected to be only about 90 percent effective, some action would
still be required to isolate the tailings from the biosphere. The
leachate would probably have to be controlled in a licensed radioactive
waste burial site. Tailings from this process would still require some
treatment, though the radioactivity level would be considerably lower.
Some hazardous nonradiological elements would remain. A potential
problem is that seepage from the new pile would contain nitrates
instead of the sulfates found in a conventional mill tailings.
Nitrates become quite mobile if they reach ground water.
The construction and operation of a nitric acid leaching mill is
quite expensive. The NRC FGEIS (NRC80) estimates that a model nitric
acid leaching mill costs $47 million to construct and an additional $50
million to equip (1981 dollars), while operating costs are expected to
run $17 per ton of processed uranium mill tailings.
The normal size generic pile contains 1.48 million short tons of
tailings. Assuming that a model nitric acid leaching mill can process
1,984 short tons of mill tailings and produce 55 short tons of nitric
acid leachate per day, then 750 days of operation would be required to
process the mill tailings. In addition, approximately 41,000 short
tons of nitric acid leachate will be generated. Consequently, the
total operating cost for a model nitric acid leaching mill at the model
inactive mill tailings pile is expected to run $25 million.
B-18
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Some of the construction materials used in a model nitric acid
leaching mill might be employed at more than one inactive mill tailings
site, or might have some scrap value. These possibilities are not
analyzed here, due to the uncertainties of apportioning construction
costs and determining future scrap values. We therefore assume that
each inactive mill tailings site requires building a new nitric acid
leaching mill at a cost of $47 million.
On the other hand, we assume that the nitric acid leaching
equipment can be used at more than one inactive mill tailings site. As
a result, cost of the nitric acid leaching equipment is equal to its
depreciated value. Assuming two years of use at the model inactive
mill tailings site, a 15-year life expectancy for the nitric acid
leaching equipment, and straight-line depreciation, the expected cost
of the nitric acid leaching equipment is $7 million at each model
inactive mill tailings site. An additional $7 million is added to
cover the costs of transportation between different mill tailings
sites, set-up and take-down costs, and extra wear and tear on the
equipment, as well as other contingencies.
We therefore expect the total nitric acid leaching equipment costs
to be about $14 million. In total, we expect nitric acid leaching to
cost about $82 million (1981 dollars) to construct, equip, operate and
close down a plant for a normal tailings pile.
When combined in an asphalt or cement matrix, the nitric acid
leachate matrix has a volume of 19,000m-' and requires a 10-meter
cover for proper disposal. The disposal of the nitric acid leachate
would require a 15-meter pit covering an area of 0.5 hectares (100m by
50m). The possible costs of nitric acid leachate disposal are
presented in Table B-5.
The NRC-FGEIS (NRC80) estimates that the concentration of radium
remaining in the residual tailings after nitric acid leaching is at
least an order of magnitude greater than background levels. If soil
with average radon attenuation properties is available in the area, a
3.8-meter cover will provide attenuation to O.lpCi/m^s. Assuming
that the nitric acid leaching process insignificantly alters the
quantity of residual tailings, the control costs for the residual
tailings can be computed. The costs of controlling the residual
tailings are presented in Table B-6.
In summary, nitric acid leaching of the tailings for the model
inactive mill site will cost $82 million. Under the best conditions,
disposal of the nitric acid leachate can be expected to cost an
additional $800,000 (normal soil excavation, stabilization with
vegetation—no irrigation required—and isolation with a chain-link
fence). Under the worst conditions, disposing of the nitric acid
leachate will cost $1,300,000 (shale excavation, riprap stabilization
and security fence for isolation). Control costs for the residual
tailings will be $9 million at best; that is, if no liner is required,
B-19
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TABLE B-5. COSTS OF NITRIC ACID LEACHATE DISPOSAL
(1981$ in thousands)
Task Cost
Earth work
Normal digging $300
Shale $450
Fixation
Asphalt $840
Cement $570
Stabilization
Vegetation
No need to purchase soil $6
With soil purchase $45
Irrigation $3
Rock $90
Gravel $15
Chemical $5
Fencing'3)
Chain link $15
Security (prison grade) fence $53
Future costs
Irrigation $15
Chemical stabilization $45
Chain link fence $3
Value of land $2
^'Includes a 20m isolation around the disposal pit.
B-20
-------
TABLE B-6. COSTS OF CONTROLLING RESIDUAL TAILINGS
(1981$ in thousands)
Task Cost
Earth Work
Clay liner not required
Normal digging $4,200
Shale $6,290
Liner
Clay
With clay available $320
With clay purchase $780
Asphalt $280
Synthetic $700
None
Tailings excavation, loading,
spreading and compacting $1,500
Tailings transportation
Truck $1,300
Truck and rail $1,100
Pipeline $1,270
Stabilization
Vegetation
No need to purchase soil $130
With soil purchase $440
Irrigation equipment $30
Riprap $2,280
Gravel $450
Chemical $130
Fencing
Chain link $50
Future Costs
Irrigation equipment $100
Chemical stabilization $500
Chain-link fence $10
Value of land $20
B-21
-------
excavation is in normal soil, tailings are transported by truck and
rail, vegetation requiring no irrigation is used to stabilize the
control site, and the control site is isolated with a chain-link
fence. On the other hand, the costs of controlling the residual
tailings could be as high as $17 million if a clay liner is used and
the clay must be purchased; if the pit excavation is in shale and
trucks are the only transportation available for the tailings; if the
control site is stabilized by riprap and isolated by a security fence.
As a result, the cost of controlling uranium mill tailings at the
normal size generic pile, using a nitric acid leaching process, could
be expected to range between $92 and $100 million.
Long-Term Radon and Hydrology Control
It is unreasonable to expect that the uranium mill tailings can be
completely isolated at many of the existing sites for periods much
longer than 1,000 years. The concept of such long-term isolation (of
both radon and ground water) essentially requires special site
selection and emplacement techniques. The NRC FGEIS (NRC80) describes
two methods that conceivably will meet these criteria: control in an
open-pit mine and control in a deep underground mine.
In the case of an open-pit mine, the mill tailings may be loosely
deposited in the pit but enclosed in a watertight liner and cap, or
they can be combined with asphalt or cement to prevent leaching into
the surface and ground water environment. Table B-7 presents cost
estimates which assume an available open-pit coal mine or copper quarry
within 10 miles. Long-term radon and hydrology control could cost as
little as $10 million. This includes expenses only for excavating
tailings by dragline, transporting tailings by truck and rail, and
enclosing loose tailings in a watertight liner and cap. These cost
estimates are relatively low because it is assumed that there is an
operating open-pit mine close to the mill tailings pile, and that the
mine owners are willing to cover the mill tailings at no cost as part
of their post-operation reclamation of the mine site.
On the other hand, costs could increase to $86 million, if the
mill tailings are deposited in an abandoned open pit mine, transported
by truck, dried by a thermal evaporator, and incorporated into an
asphalt matrix. It is also assumed that the control site is stabilized
with vegetation, requiring the purchase of suitable top soil. Unlike
the previous control levels, however, there is no long-term commitment
to institutional maintenance and the site will be available for
alternative future uses.
In another approach, it is assumed that a nearby abandoned under-
ground mine is available. In this case, it is assumed that the tailings
will need to be fixed in an asphalt or cement matrix to prevent
B-22
-------
TABLE B-7. COST ESTIMATES FOR CONTROLLING URANIUM TAILINGS
WHEN A NEARBY OPEN-PIT MINE IS AVAILABLE
(1981$ in thousands)
Task Cost
Evacuate & load tailings $1,800
Tailings transportation
Truck $2,000
Truck & rail $1,700
Pipeline $2,000
Tailings control
Loose with liner & cap $6,900
Cement fixation
Thermal evaporator $26,900
Filter bed $16,200
Asphalt fixation
Thermal evaporator $37 ,400
Filter bed $26,800
Disposal of mine contents $42,200
Vegetation cover
No need to purchase soil $1,040
Soil purchase required $6,900
B-23
-------
leaching; holes will be bored into the mine cavities for depositing the
asphalt or cement matrix. Cost estimates for control of the mill
tailings in a deep underground mine are presented in Table B-8.
Implementing this method of tailings control would cost from $20
million to $41 million.
Thermal Stabilization
Thermal stabilization involves firing the tailing to 1,200°C
(22,200°F) in a rotary kiln. The high temperature changes the
character of the tailings from predominantly crystalline to
significantly amorphous. The amorphous material traps or "locks in"
the radon and allows it to decay in place. In tests (Dr81) the
emanating power of radon (from the tailings) is reduced from about 20
percent to less than 1 percent. This greatly reduces the risk from
radon decay products if the tailings are misused as fill, soil
conditioner, or even construction material around structures.
Thode (Th81) reports that the costs of thermal stabilization and
subsequent disposal are $16 to 41 per ton of tailings. These costs can
be compared to onsite costs of $2 to $7 per ton and costs of $9 to $13
per ton for moving and controlling the tailings as developed for the
six alternatives. The cost of coal delivered to the tailings site is
the greatest variable in Thode's analysis. He concludes that thermal
stabilization could be economical under some or all of the following
conditions:
1. Coal for kiln operations is inexpensive.
2. Topsoil for cover is not readily available.
3. Transportation costs to remote control areas are high.
4. Environmental (radiological) monitoring costs are high for
transport to remote control areas.
B.7 Remedial Costs for Cleanup of Buildings
Summary of Relevant Data from the Grand Junction Remedial
Action Program
To estimate cleanup costs for buildings, we have relied on
experience accumulated in the Grand Junction remedial action program.
This section summarizes the relevant experience for 217 buildings
covered by that program for which data is available (Co81). Of the 217
buildings, 88 percent were residential buildings; the rest were
commercial buildings (offices, motels, retail stores, etc.) and
schools.
Cleanup costs are largely determined by the number of buildings
requiring cleanup with passive measures (i.e. tailings removal). This
number can be estimated from the distribution of radon decay product
levels measured in the residential buildings (See Table 3-7) before
remedial work was undertaken. (Nonresidential buildings are assumed
B-24
-------
TABLE B-8. COST ESTIMATES FOR CONTROLLING URANIUM TAILIN3S
WHEN A NEARBY UNDERGROUND MINE IS AVAILABLE
(1981$ in thousands)
Task Cost
Evacuate & load tailings $1,800
Tailings transportaton
Truck $2,000
Truck & rail $1,600
Pipeline $1,900
Bore holes $30
Tailings control
Cement fixation
Thermal evaporator $27,800
Filter bed $16,200
Asphalt fixation
Thermal evaporator $37,400
Filter bed $26,800
B-25
-------
to have the same distribution). We then determine the number or
percentage of buildings which would have qualified for remedial action
under alternative action levels for passive and active remedial
work.
Different remedial action levels also influence costs because
lower remedial action levels are harder to achieve; at lower levels a
remedial effort will sometimes fail to reduce sufficiently the radon
decay product of a buildings. This results in extra costs because
these buildings will require more than one remedial action. Table B-9
shows the percent of buildings in the Grand Junction sample which
exceed selected levels of radon decay products after the first remedial
action effort or contract. The average number of contracts required to
meet each level is determined by the formula l/(l-x) where x is the
fraction equivalent of the percent value in Table B-9.
The average cost of each passive remedial action (i.e. contract
for residences) since the Grand Junction remedial action program began
in 1972 has been about $10,000 (Co81). The cost for nonresidential
buildings has averaged close to $50,000. Given the proportion of
residential buildings, the average remedial cost for all buildings is
about $15,000. If we multiply this by an inflation factor of 1.7 we
arrive at a present average passive remedial cost per building of
roughly $25,000 (1981 dollars).
Available active measures (discussed earlier) are much cheaper.
These would cover a range of initial and maintainance costs, but for
this exercise, we have used $2,500 as the average present cost of an
active remedial measure.
Estimation of Costs
In order to estimate the cleanup cost under each alternative, it
is necessary to make some specific assumptions about flexibility in
using the numbers in some of the alternatives and under what
circumstances active remedial measures will be used instead of (or in
addition to) passive measures. These assumptions are outlined below:
Option Bl: All buildings exceeding 0.015 WL would receive one
initial passive remedial action. However, after the first attempt at
tailings removal, buildings exceeding this level by less than 0.01 WL
are assumed to receive active remedial action.
Option B2: All buildings initially exceeding 0.02 WL by more than
0.005 WL would receive passive remedial action. The rest (between 0.02
and 0.025 WL) would receive active measures. For subsequent actions,
those still exceeding 0.02 WL by more than 0.01 WL would receive
additional passive actions while those between 0.02 and 0.03 WL would
receive additional active measures.
B-26
-------
TABLE B-9. PERCENT OF RESIDENCES REMAINING ABOVE A SELECTED
RADON DECAY PRODUCT LEVEL AFTER FIRST PASSIVE REMEDIAL ACTION
(a)
Selected Radon
Decay Product
Concentration
(WL)
Buildings Exceeding
Selected Concentration
After One Passive
Remedial Action
(Percent)
Estimated Average
Number of Actions
Required to Meet the
Selected Concentration
0.015
0.017
0.020
0.025
0.030
0.037
0.057
39
29
22
17
12
8
3
1.6
1.4
1.3
1.2
1.13
1.08
1.03
(a'Grand Junction Data.
(^'Assuming that only passive remedial actions are used.
B-27
-------
Option B3: All buildings initially exceeding 0.02 WL by more than
0.005 WL would receive passive remedial action. The rest (between
0.012 and 0.025 WL) would receive active measures. For subsequent
actions, those exceeding 0.02 WL by more than 0.01 WL would receive
passive actions while those between 0.01 and 0.03 WL would receive
active measures.
Option B4: All buildings initially exceeding 0.017 WL (0.007 WL
above background) would receive passive remedial measures. For
subsequent remedial actions only those exceeding 0.037 WL (0.03 WL
above background) would receive additional passive remedial actions.
No active measures are used in this alternative.
Using Grand Junction data, we have estimated in Table B-10 the
number of contaminated buildings (covered by the cleanup mandated by
the Act) with radon decay product levels initially above selected
levels. Using this table in conjunction with Table B-9, cost data
previously cited, and the implementation assumptions just detailed, we
are able to estimate the cleanup costs under the various alternatives:
Option Bl: Table B-10 shows that 370 buildings would require
initial passive remedial actions. Table B-9 shows that these buildings
would require 1.2 remedial actions on the average. Thus the total cost
of passive remedial actions would be 370 x 1.2 x $25,000 = $11.1 million.
We have assumed another 100 active remedial actions would be needed at a
cost of $0.25 million. Thus the total remedial cost would be about
5 million.
Option B2: Table B-10 shows that 290 buildings would require an
initial passive action and Table B-9 shows that subsequent remedial
actions will increase the number of needed actions by a factor of 1.13.
Thus the total costs of passive remedial action would be $8.2 million.
An additional 100 active remedial actions would add $0.25 million to
this for a total of roughly $8.5 million.
Option B3: Like B2, B3 will cost $8.2 million for passive remedial
action. We have further assumed 300 active remedial actions for a total
cost of $0.75 million, bringing the total cost to about $9 million.
Option B4: In this option, 350 buildings will require a passive
remedial action. Subsequent actions will increase the number of actions
by a factor of 1.08, because remedial actions stop when 0.03 WL is
achieved. The total cleanup costs will, therefore, be about $9.5
million.
B-28
-------
TABLE B-10. ESTIMATED NUMBER OF CONTAMINATED BUILDINGS
EXCEEDIN3 SELECTED CONCENTRATIONS OF RADON DECAY PRODUCTS
Selected Radon Decay Number of Buildings
Product Concentration Exceeding the
(WL) Selected Concentration(a)
0.012
0.015
0.017
0.02
0.025
0.03
0.04
0.05
420
370
350
330
290
245
175
125
'Based on Grand Junction data, chis is the number of buildings
we estimate to be now contaminated above each level with tailings
from all inactive tailings piles.
B-29
-------
REFERENCES
AMC81 American Mining Congress, "Comments in Regard to Proposed
Cleanup and Disposal Standards for Inactive Uranium Processing
Sites (Docket No. A-79-25)," before the U.S. Environmental
Protection Agency, July 15, 1981.
DG81 Dodge Guide to Public Works and Heavy Construction Cost,
Annual Edition No. 13, McGraw-Hill, 1981.
Dr81 Dreesen D.R., Williams J.M. and Cokal E.J., "Thermal
Stabilization of Uranium Mill Tailings," in: Proc. 4th
Symposium Uranium Hill Tailings Management, Fort Collins,
Colorado, October 1981.
EPA80 Environmental Protection Agency, Draft Environmental impact
Statement for Remedial Action Standards for inactive uranium
Processing Sites (40 CFR 192), EPA 520/4-80-011, Office of
Radiation Programs, USEPA, Washington, D.C., December 1980.
HalP Hans J.M. Jr., Burris E., Gorsuch T., Radioactive Waste
Management at the Former Shiprock uranium Mill Site,
Environmental Protection Agency Technical Note (in
preparation).
NRC80 Nuclear Regulatory Commission, Final Generic Environmental
Impact Statement on Uranium Milling, NUREG-0706, Washington,
D.C., September 1980.
PE81 PEDCO Environmental Inc., Evaluation of Costs to Control
Fugitive Dust from Tailings at Active Uranium Mills, EPA
Contract No. 68-02-3173, Task No. 053, USEPA, Washington,
D.C., August 1981.
Ro81 Rogers V.C. and Sandquist G.M., Long-Term Integrity of
Uranium Mill Tailings Covers, Report to NRC, RAE-21-1 Rev. 1,
August 1981.
Th81 Thode E.F. and Dressen D.R., "Technico-Economic Analysis of
Uranium Mill Tailings Conditioning Alternatives," in: Proc.
4th Symposium uranium Mill Tailings Management, Fort Collins,
Colorado, October 1981.
B-30
-------
APPENDIX C
TOXIC SUBSTANCES IN TAILINGS
-------
APPENDIX C: TOXIC SUBSTANCES IN TAILINGS
CONTENTS
C.I CONCENTRATION OF POTENTIALLY TOXIC ELEMENTS IN TAILINGS C-5
C.2 ACUTE AND CHRONIC TOXICITY C-8
Acute Toxicity C-8
Chronic Toxicity C-9
C.3 ESTIMATES OF THE CONCENTRATION EXPECTED TO PRODUCE CHRONIC
TOXICITY C-10
Estimates of Chronic Toxicity in Humans C-10
Estimates of Toxicity in Livestock C-ll
Estimates of Toxicity in Crops C-14
C. 4 ESTIMATE OF HAZARDS FROM TAILIN3S C-17
Water C-17
Food and Feeds C-18
C. 5 PLANTS AND ANIMALS ON TAILINGS PILES C-21
Plants C-21
Animals C-24
TABLES
C-l Elements Present in Tailings from Acid-Leach Mills and in
Typical Soil C-6
C-2 Selected Elements Measures in Soils and Rock C-7
C-3 Ratio of Toxic Intake to the Recommended Daily Allowance .... C-10
C-4 Comparison of Daily Intake Levels of Selected Elements C-ll
C-5 Concentration of Elements in Animal Ration Leading to
Chronic Toxicity C-12
C-6 Concentrations of Elements in Water Potentially Toxic to
Livestock C-13
C-7 Recommended Maximum Concentrations of Elements in Water for
Livestock C-13
C-3
-------
APPENDIX C: TOXIC SUBSTANCES IN TAILINGS
CONTENTS (Continued)
C-8 Maximum Concentration of Elements in Irrigation Water Not
Immediately Toxic to Crops C-15
C-9 Concentrations of Elements in Irrigation Water and Soil
That Could Be Immediately Toxic to Crops C-16
C-10 Estimated Average Daily Intake of Foods by Selected
Age Groups C-20
C-ll Estimated Concentration of Elements in Soil That Will
Produce a Concentration of 1 ppm in Crops C-22
C-12 Soil Concentrations of Elements that Might be Associated with
Toxic Concentrations in the Food Pathway C-23
ANNEX 1—TOXICOLOGY OF SELECTED ELEMENTS FOLLOWING ORAL
ADMINISTRATION C-25
ARSENIC C-27
BARIUM C-27
BORON C-28
CADMIUM C-28
CHROMIUM C-29
COPPER C-29
CYANIDE C-30
IRON C-30
LEAD C-30
MANGANESE C-31
MERCURY C-31
MOLYBDENUM C-32
NICKEL C-32
NITRATE C-33
RADIUM C-33
SELENIUM C-34
SILVER C-34
THORIUM C-3 5
URANIUM ".I!!!!!!!! c-s 5
VANADIUM [mf c-36
REFERENCES c_3 7
C-4
-------
Appendix C: TOXIC SUBSTANCES IN TAILINGS
In this appendix, we examine the toxic hazards posed by non-
radioactive elements that may be present in tailings piles. We describe
the types of toxicity and also (in Annex 1) describe the toxicologies of
many elements likely to be found in tailings piles. We describe the
various levels of concentration of substances that are known to be toxic
to humans, animals, and plants and estimate the hazards from tailings.
Because not all tailings piles have the same characteristics, evaluation
of toxic hazards from tailings must be made on a site-specific basis.
The discussion of toxicity of these elements is not meant to be
exhaustive; only acute and chronic toxicity data are usually mentioned.
No attempt was made to quantitatively assess toxic element carcino-
genesis, teratogenesis, or mutagenesis (God77, Ve78) because of both the
scarcity of dose-response data and the controversy surrounding attempts
to extrapolate data from animal carcinogenesis studies to human
dose-response estimates for oral exposure (when data is available).
Likewise, no attempt was made to quantitatively evaluate effects of
chemical elements on specific organ systems, e.g., the cardiovascular
system (CaaSO) or factors influencing the toxicity of elements (Le80,
EH78) as these also are unquantified or controversial toxic effects.
C.I Concentration of Potentially Toxic Elements in Tailings
Compared to surrounding soils, mill tailings contain high
concentrations of many chemical elements, some of which may be toxic.
Some of these elements were laid down in the ore-bearing rock over the
same time period during which the uranium was concentrated and by the
same processes that concentrated the uranium, while other elements were
introduced during ore processing. Since there is a detailed analysis of
background soil around the tailings at only one tailings site (Dr78),
some authors have compared tailings to "typical" soil (DrSla, Table 3-3
of this EIS) or to sedimentary rock (Ma81). Such analyses may give
misleading estimates of the extent and potential added impact of
elemental concentration in tailings.
Dreesen and co-workers have made relatively detailed analyses at
four pile sites (Dr78, DrSla) in Table C-l and Table 3-3. Markos and
Bush (Ma81) have summarized published data for 19 piles, and an
adaptation of their work is shown in Table 3-2.
C-5
-------
TABLE C-l. ELEMENTS PRESENT IN TAILINGS FROM ACID-LEACH MILLS
AND
IN TYPICAL SOIL
Concentration of
Element
Uranium
Molybdenum
Selenium
Vanadium
Arsenic
Chlorine
Antimony
Calcium
Cerium
Bromine
Sodium
Iron
Terbium
Cobalt
Aluminum
Barium
Europium
Gallium
Lanthanum
Manganese
Scandium
Zinc
Chromium
Potassium
Thorium
Titanium
Ytterbium
Cesium
Hafnium
Magnesium
Rubidium
Tantalum
Strontium
Tungsten
Mercury
Lead
Copper
Tin
Nickel
"Typical"
Soil
1.0
2.0
0.2
100
6
100
2-10
14000
50
5
6000
38000
0.6
8
71000
500
0.5
30
30
850
7
50
100
14000
5
5000
2
6
6
5000
100
0.8
300
1
.03
10
20
—
40
|(b)Salt Lake
City, Utah
58-271
330-550
5.9-69
158-3040
73-419
55-6820
8.6-160
25000-82000
44-159
<1.4-6.3
4000-10000
8000-316000
<0.2-1.3
5.5-42
20000-67000
194-3860
0.35-1.33
<19-76
10.9-35.7
79-2080
3.0-9.5
<24-350
22-7250
<5000-25000
4.5-33.1
1420-5660
-------
TABLE C-2. SELECTED ELEMENTS MEASURED IN SOILS AND ROCK
n
I
Concentration
in Soil
(parts per million)
Element Symbol
Aluminum Al
Antimony Sb
Arsenic As
Barium Ba
Boron B
Cadmium Cd
Chromium Cr
Cobalt Co
Copper Cu
Iron Fe
Lead Pb
Manganese Mn
Mercury Hg
Molybdenum Mo
Nickel Ni
Radium- 226 Ra
Selenium Se
Silver Ag
Thorium Th
Tin Sn
Uranium U
Vanadium V
z,inc Zn
( a ^ Concentrations
(°) Concentrations
(c> (Ma 81) .
(<*> (Cao77) .
(a)
Background
3730
0.48
4.4
351
—
—
22
3.7
—
1210
—
167
—
1.9
—
—
1.3
—
6.2
—
2.4
20
29
measured in soil
in a hypothetical
"n" represents any digit from 1 to
"Typical "(b)
71000
2-10
6
500
—
0.06
100
8
20
38000
10
850
0.03
2.0
40
1.5 x 10~6
0.2
0.1
5
—
1.0
100
50
around a tailings
(c)
Sedimentary
—
O.On
1
nO.O
—
—
35
0.3
1
28000
7
400
—
0.2
2
—
—
O.On
—
O.n
—
20
16
pile by Dreesen,
Concentration
in Rock
(Parts per million)
Sandstone
25000
0.05
1
50
35
0.05
35
0.3
5
9800
7
50
0.03
0.2
2
7 x 10- 7
0.05
0.05
1.7
0.5
0.45
20
16
et al. , (Dr78) .
(d)
Limestone
4200
0.2
1
120
20
0.035
11
0.1
4
3800
9
1100
0.04
0.4
20
4 x 10~7
0.08
0.05
1.7
0.5
2.2
20
20
Shale (d)
80000
1.5
13
580
100
0.3
90
19
45
47200
20
850
0.4
2.6
68
1.1 x 1CT6
0.6
0.07
12
6
3.7
130
95
"typical" soil (Bo66) .
9.
-------
Most of the uranium ores mined in the United States are obtained
from sandstones, but some also come from limestones and lignites (La80).
Table C-2 lists concentrations of elements in selected soil and rock.
The extent to which toxic elements are concentrated during processing of
uranium ore can be determined by comparing the concentration in tailings
witn that in rock from which the ore was mined. However, this is not a
proper measure of the hazards associated with tailings. Rather, the
ratio of an element's concentration in the tailings to that in the soil
surrounding the tailings is one acceptable measure of the potential
hazard associated with the tailings. This concentration ratio is also a
measure of the potential for contaminating ground water. If the ratio is
low (e.g., <5), there is little potential for contaminating soil or
ground water; if it is high (e.g., 25), then the situation should be
carefully evaluated so that contamination of soil or of ground water can
be avoided.
Regardless of the basis for comparison, e.g., background soil or
sandstone, when Table 3-2 is compared to Table C-2, all elements are
noted in elevated concentrations at one or more tailings sites. Since
all sites have one or more element present in elevated concentrations, at
each site these elements will have to be further evaluated on the basis
of the levels at which toxicity is expected to occur in man and animals.
C.2 Acute and Chronic Toxicity
Many of the elements present in tailings are essential to life;
others, as far as is known, are only toxic. However, as Mertz (Me81) and
others before him have pointed out, essential elements follow Bertrand's
rule, which says that for essential elements there is a level of intake:
1. So low that deficiency symptoms develop;
2. Low enough that the function of the organism is marginal;
3. Adequate, so that function is optimal;
4. High enough that function becomes marginal;
5. So high that toxicity symptoms develop.
With tailings, our concern is for the toxic effects associated with
high levels of intake. In the following sections, only acute and chronic
toxicity are discussed. Mutagenesis, carcinogenesis, and teratogenesis
are not considered due to lack of quantitative data on intake levels
associated with these toxic responses.
Acute Toxicity
In sufficient quantity, adl elements can cause an acute toxic
response or death. Acute toxicity is a threshold type of response; i.e.,
unless the concentration of toxic elements in the food or water consumed
C-8
-------
is great enough, acute toxicity symptoms will not develop. The amount of
an element that must be consumed to produce these symptoms is usually
specific for both the element and the chemical form in which the element
is consumed (Ve78). Symptoms such as nausea, vomiting, extreme
discomfort or pain, convulsions, and coma may occur, depending on the
element involved (Un77, Ve78, God77). These symptoms develop very
rapidly after consumption of the toxic element and in some cases
eventually lead to death.
Acute toxicity, however, does not appear to be a major consideration
in tailings disposal decisions. Unless the fresh-tailings pond liquid or
ground or surface water with a pulse of high-level contamination from the
tailings is consumed, it is unlikely that elements from tailings would be
present at a concentration high enough to cause an extremely rapid toxic
response.
Chronic Toxicity
Most elements can produce chronic toxicity. This condition usually
occurs after continuous consumption of the element at levels well below
those that cause acute toxicity. Many elements are quite insidious,
since they slowly accumulate in tissues and cause the symptoms of
toxicity only after a specific minimum amount has accumulated in the body
(Ve78, God77). Symptoms such as lethargy, impaired function of specific
organs, growth disturbances, and changes in levels of specific enzymes
develop gradually and may not be noticed until they are well developed.
Much of the human data on chronic toxicity are anecdotal and do not
provide an adequate base for dose-response analysis or for establishing a
good "no observed effect" level. While some data on chronic toxicity are
available for laboratory and domestic animals, they often refer to less-
than-lifetime exposure and are for poorly defined doses. Also, there is
great species variation in sensitivity to specific elements and in the
physiological response to the element. So, although there are some "no
observed effect" levels established for a few species, the overall
picture of chronic toxicity is incomplete.
To provide a better understanding of some of the considerations
involved, the toxicologies of the following selected substances found in
tailings are summarized in Annex 1 following this appendix.
arsenic mercury
barium molybdenum
boron nickel
cadmium nitrates
chromium radium
copper selenium
cyanide silver
iron thorium
lead uranium
manganese vanadium
C-9
-------
C. 3 Estimates of the Concentration Expected to Produce Chronic Toxicity
Estimates of Chronic Toxicity in Humans
There is relatively little data on chronic toxicity of trace elements
in humans. However, the National Academy of Sciences has presented
material in the report, "Drinking Water and Health, Volume 3," (NAS80),
which permits an estimate of a daily intake that might cause chronic
toxicity. Recommendations are presented in Table C-3 as ratios of the
toxic intake level to the intake level recommended by the National Academy
of Sciences to satisfy nutritional requirements (Recommended Daily
Allowances—RDA) in adult humans.
TABLE C-3. RATIO OF TOXIC INTAKE TO THE RECOMMENDED
DAILY ALLOWANCE (NAS80)
Ratio of Toxic Intake to Adult
Element Required Daily Intake
Arsenic 10
Chromium 1000
Copper 40-135
Iron 340-1700
Manganese 120
Molybdenum 10-40
Nickel 112
Selenium 100
Vanadium 50-450
Zinc 40-280
The National Academy of Sciences characterized human daily intakes
as Recommended Dietary Allowances (RDA's) when requirements were well
defined or Adequate and Safe Intakes when human requirements are not well
established. They also recommended intake levels for arsenic, nickel,
and vanadium, although nutritional requirements for these elements are
not even well established for any animals.
The estimated daily intakes, in milligrams, of elements that may
cause chronic toxicity are listed in Table C-4. We have calculated these
intakes using the ratios shown in Table C-3; because the estimated toxic
daily intake is uncertain, actual intakes of these elements probably
should not be allowed to exceed one tenth of the calculated values.
Estimates of total daily intake can be calculated on the basis of the
concentration of an element in'the food and water (in parts per million
(ppm) or micrograms per gram (ug/g)) and the amount of each consumed by
persons living near the tailings. These can then be compared to the
estimates of potentially toxic intake in Table C-4 to determine the
C-10
-------
TABLE C-4. COMPARISON OF DAILY INTAKE LEVELS OF SELECTED ELEMENTS
Element
Arsenic
Chromium
Copper
Recommended
Dietary
Allowances
-
(in mg)
Adequate
and
Safe Intake13'
(0.025-0.05) (c)
0.05-0.20
2-3
Typical
Food
Intake (a)
0.0114
^
19
1-6.4
0.10
0.165-0.500
0.15
0.02
12
3000-20000
6000-30000
300-600
2-20
6
5-20
1-3
600-4000
(NAS80).
-------
Water consumption estimates may have to be increased by a factor of two
to three in hot weather, and those for dairy cattle increased further
by a factor of two to three for higher milk production.
TABLE C-5. CONCENTRATION OF ELEMENTS IN ANIMAL RATION
LEADING TO CHRONIC TOXICITY(a)
(in ppm)
Element
Copper (b~e)
Lead(f>
Manganese (°)
Molybdenum(c'd)
Selenium (Ro74).
(f)(NAS72a).
(9)(Fib77).
From the preceding estimates of water consumption and toxicity,
when the intake in feed leading to toxic symptoms is reported, an
estimate can be calculated of the concentration in water leading to a
similar intake of the element. For example, concentrations in ration
leading to chronic toxicity (Table C-5) have been translated, on the
basis of water consumption only, to the potentially toxic water
concentrations in Table C-6.
Almost all micronutrients and elements seem to interact with one
another in some way, but specific recommendations are difficult to make
because of incomplete data on all elements in food and water (Sa80).
Therefore, it would seem prudent to limit the levels of toxic elements
in water given to livestock. .Reasonable levels to recommend for
continuous consumption of water might be one tenth of the lowest level
expected to lead to chronic toxicity, as calculated in Table C-6.
These levels are shown in Table C-7.
C-12
-------
TABLE C-6. CONCENTRATIONS OF ELEMENTS IN WATER
POTENTIALLY TOXIC TO LIVESTOCK
(in ppm)
Element
Copper
Lead
Manganese
Molybdenum
Selenium
Vanadium
Zinc
Beef Cattle
37.8-94.3
56.6
3.8-18.9
0.75-1.5
3.8
170-321
Dairy Cattle
5-13
7.7
0.51-2.6
0.10-0.20
0.51
23-44
Sheep
67-100
260-467
3.3-13.3
2.7-6.7
13.3
467-1000
Swine
100-300
200
400
2.8-6
1600+
Poultry
533-1067
53
667+
133-2667
5.3-10
23 +
800-933
TABLE C-7. RECOMMENDED MAXIMUM CONCENTRATIONS OF ELEMENTS
IN WATER FOR LIVESTOCK
(in ppm)
Element
Estimates based on Table C-6
NAS Recommendations
for Livestock (NAS72c)
Aluminum
Arsenic
Boron
Cadmium
Chromium
Cobalt
Copper
Fluoride
Lead
Manganese
Mercury
Molybdenum
Nitrate-N
Selenium
Vanadium
Zinc
_
-
-
-
_
-
40
—
5
20
-
0.3
_
0.1
0.4
20
_
-
-
-
-
-
(0.5 for dairy cattle)
—
(0.5 for dairy cattle)
-
-
(0.05 for dairy cattle)
-
(0.01 for dairy cattle)
(0.05 for dairy cattle)
(2 for dairy cattle)
5
0.2
5
.05
1
1
0.5
2
0.1
-
.01
—
100
0.05
0.1
25
C-13
-------
For most of the elements addressed in Table C-7, the NAS in 1972
had recommended concentrations in water for livestock. However, in the
case of many elements, the NAS proposed upper limits in water were
based on the usually low natural level of the element in sources of
water rather than the toxicity of the element. Thus, in Table C-7- the
estimates based on Table C-6 and the NAS recommendations are, not
surprisingly, different because their bases are different.
The levels of elements in Table C-6 have about a tenfold
uncertainty. Also, the estimated toxic level would vary by site.
Estimated levels in water causing toxicity may be increased by a factor
of two to three for interactions of various elements (e.g., high copper
partially offset by high zinc and iron) or be increased a factor of two
or three because of differences in biological availability of various
elements. On the other hand, the estimated level in water causing
toxicity may have to be reduced a factor of two or three in the case of
larger animals or higher average temperatures. The level may also have
to be decreased to allow for high levels of the same elements in forage.
Estimates of Toxicity in Crops
In their publication, "Water Quality Criteria, 1972," the National
Academy of Sciences (NAS72c) estimated levels of elements in irrigation
water that might be toxic to agricultural crops grown using such water
(Table C-8). The authors considered these elements to be retained in
the soil and to reach a level toxic to crops in 20 years or 100 years,
depending on soil type. Since a negligible concentration of the
elements was removed from the soil by crops during the 20- or 100-year
period of irrigation, the soil concentrations would build up and would
be in the range of concentrations that had been reported in published
literature to be toxic to crop plants. No specific consideration was
given to bioaccumulation, bio concentration, or biological availability
of the elements in crops. Note that for some of the elements
addressed, water meeting the Maximum Contaminant Levels in the National
Interim and Secondary Drinking Water Regulations would not be suitable
for irrigation.
The estimate of irrigation water concentrations developed by the
National Academy of Sciences also provides a way to estimate soil
concentrations of equivalent impact. In the NAS estimate (NAS72c),
irrigation water is used at a rate of 3-acre ft/acre per year, so that
an element present at 1 ppm will be deposited at the rate of
8.13 Ibs/acre per year, mixed in the top 6 inches of soil. For
example, if the soil weighs 1.5 grams per cubic centimeter, 1 ppm in
irrigation water would yield a soil concentration of 4 ppm in soil per
year of irrigation.
This conversion factor is^ used to estimate the concentration in
soil toxic to crops (Table C-9). The soil concentrations calculated
are for ions or soluble salts of the element and not for the total
concentration of the element in soil. Soils containing elements at
C-14
-------
TABLE C-8. MAXIMUM CONCENTRATION OF ELEMENTS IN IRRIGATION WATER
NOT IMMEDIATELY TOXIC TO CROPS (NAS72c)
(in ppm)
Element
Water used continuously
on all soils (calculated on
the basis of 100 years)
Water used up to 20
years on fine textured
soils of pH 6.0 to 8.5
Aluminum^ a^
Arsenic
Beryllium
Boron
Cadmium
Chromium
Cooalt
Copper
Fluonae
Iron
Lead
Lithium
Manganese
Molybdenum
Nickel
Selenium
Vanadium
Zinc
5.0
0.10
0.10
0.75
0.01
0.10
0.05
0.20
1.0
5.0
5.0
2.5
0.20
o.oio(c>
0.20
0.02(0
0.10
2.0
20.0
2.0
0.5
2.0
0.05
1.0
5.0
5.0
15.0
20.0
10. 0
2.5
10.0
0.053 when necessary.
75 ug/1 for citrus crops.
Rased on potential toxicity in animals.
Relatively high iron oxide content in soil.
C-15
-------
TABLE C-9. CONCENTRATIONS OF ELEMENTS IN IRRIGATION WATER AND SOIL
THAT COULD BE IMMEDIATELY TOXIC TO CROPS
(in ppm)
Element
Finely Textured Soils
(pH 6.0 to 8.5)
Irrigation Waterva/ Soil Irrigation Water^ ' Soil
All Soils
Aluminum
Arsenic
Beryllium
Boron
Cadmium
Chromium
Cobalt
Copper
Fluoride
Iron
Lead
Lithium
Manganese
Molybdenum
Nickel
Selenium
Vanadium
Zinc
500
10
10
75
1
10
5
20
100
500
500
250
20
l(d)
20
2(d)
10
200
2
0.04
0.04
0.3
0.004
0.04
0.02
0.08
0.4
2
2
1
0.08
0.004
0.08
0.008
0.04
0.8
400
40
10
40
1
20
100
100
300
400
200
50(c)
200
l(d,e)
40
0.4
20
200
1.6
0.16
0.04
0.16
0.004
0.08
0.4
0.4
1.2
1.6
0.8
0.2
0.8
0.004
0.16
0.0016
, 0.08
0.8
(c)
(d)
years times the appropriate concentration from the first
column of Table C-8.
years times the appropriate concentration from the second
column of Table C-8.
7.5 ppm for citrus crops.
Based on potentially high toxicity in animals.
'e'Relatively high iron content in soil.
NOTE: Soil concentrations listed here are concentrations of the
element in ionic or soluble form and do not represent the
total soil concentration of the element.
C-16
-------
concentrations shown in Table C-9 would probably not be good for
agricultural needs regardless of whether windblown or water-borne
tailings were the source of the contamination. Because of differences
among tailings sites in elements and concentrations of elements, soils,
and plant life, the possibility of toxicity to plants from tailings
should be considered on a site-specific basis. Shacklette, et al.,
have reviewed much of the literature on trace elements in plants and
have listed reported concentrations of elements in various plants and
estimates of their potential toxicity >(Sha78) . Some plants and
foodstuffs probably should not be grown or may be impossible to grow
around tailings.
The question of toxicity to humans or animals from plants grown in
the presence of tailings or irrigated with water containing elements
from tailings must also be addressed on a site-specific basis. The
question is too complex for generic analysis. Studies have shown
bioconcentration of elements by many plants. Clover concentrates
selenium and molybdenum (Fu78), and selenium and arsenic
bioconcentration has been reported in native plants growing on inactive
piles (Dr78). Such findings suggest that livestock access to
vegetation growing near (even stabilized) tailings may have to be
restricted.
The level of protection afforded human health may not be adequate
tor animals and plants. In specific cases, animal rations may have to
be supplemented or special soil conditioners used. Land and streams
near mill tailings may never be suitable for dairy or citrus farming,
or trout fishing, but, at worst, only transient economic losses would
occur.
C.4 Estimate of Hazards from Tailings
Water
Although there is no proof of ground water contamination from
inactive tailings (Chapter 4 in this EIS), the potential exists. The
daily intake of selected elements in water expected to cause toxicity
in man is given in Table C-4, and the concentrations of selected
elements in water expected to cause toxicity in animals or plants are
given in Tables C-6 to C-9. Either measured or calculated levels of
contamination in ground water can be compared with the values in these
tables to estimate the margin of safety or potential hazard associated
with use of the water.
The National Academy of Sciences (NAS72c) pointed out some of the
many differences between ground and surface waters. Movement of ground
water can be extremely slow, so that contamination of an aquifer may
not become evident at the site of use for tens, hundreds, or even
thousands of years; bodies of ground water cannot be adequately
monitored by sampling at the point of use. Mixing is different in
ground and surface waters. Dispersion in ground water is often
C-17
-------
incomplete for many years. The long underground retention of ground
water facilitates microbial and chemical reactions that may remove
pollutants.
However, because of their common use as private water supplies in
rural areas, all geologically unconfined (water-table) aquifers could
be classified as raw surface waters used for public water supplies
(NAS72c). In fact, the NAS recommended that raw ground water criteria
should be more restrictive than those for raw surface water because of
the assumption that no treatment, or very little treatment, is given to
ground water (NAS72c). This would be particularly true in rural areas,
where ground water is used extensively since its sources are generally
regarded as a more dependable supply and are less variable in
composition than surface water sources (NAS72c).
While protecting groundwater to at least the same level as
finished drinking water would provide protection to persons drinking
the untreated groundwater, the degree of protection provided by
finished drinking water will not protect livestock from all toxic
elements. Restricting water use to specific purposes may be required
in some cases to minimize not only human health effects but also
economic loss from agricultural impact.
Food and Feeds
While contamination of ground water is only a potential hazard,
contamination of soil with windborne tailings has been observed.
Douglas and Hans (Dob75) estimated the extent of windblown tailings
based on gamma count rate contours at 21 inactive sites. They reported
measurable increases due to windblown tailings at some hundreds of
meters from the piles; the maximum distance was about 1.5 km at one
pile. Schwendiman, et al. (ScbSO), sampled soil and air around a
tailings pile and assayed the samples for radioisotopes and stable
elements. At the site studied, radium-226 was found in concentrations
of 4.5 pCi/g at 4.8 kilometers and 2.25 pCi/g at 8 kilometers in the
prevailing downwind direction. Since elevated concentrations of both
radioisotopes and stable elements were measured in air samplers, stable
elements from the pile are probably distributed to the same extent as
the radium-226.
The real hazard of these windblown tailings has been demonstrated
by two analogous situations in which molybdenosis has been observed in
cattle grazing on contaminated land. In the first case, windblown
flyash from rotary kilns ashing lignite coal to upgrade the uranium
content apparently contaminated pastureland in southwestern North
Dakota (Chc68-69). In the second case, copper deficiency/molybdenosis
was associated with spoils or other sequelae of open-pit uranium mining
in Karnes County, Texas (Doa72)«. Whether the local contamination was
due to wind or to water erosion is not clear, but the source of
contamination is certain.
C-18
-------
The possibility of ingesting elements from windblown tailings via
the food pathway can be estimated, but only in a very general way. The
concentration of elements in tailings is site-specific, as are the
meteorological conditions that would disperse them. Land composition
and agricultural practices are also site-specific. All these factors
would influence a site-specific evaluation of hazards from the tailings.
The approach suggested here uses the ratio of the average
concentration of an element in tailings to the average concentration of
radium-226 in tailings as a conversion factor. This conversion factor
allows us to calculate, as a first approximation, the concentration of
the element at any point at which we know the radium-226 concentra-
tion. Since the physical processes moving tailings around the
environment are relatively independent of composition, we consider this
ratio a constant. Thus, if there is 100 ppm of an element and
100 pCi/g of radium-226 in a tailings pile, the ratio is one, and if
the measured radium-226 concentration in windblown tailings is 10 pCi/g,
the expected element concentration is 10 ppm, etc.
Radium-226 was chosen as the reference isotope since so many
studies of tailings piles have been directed to establishing the extent
of windborne contamination with radium-226 (Dob75). However, ratios
could be developed for any two elements. The distribution of
radioisotopes with distance around the pile studied by Schwendiman, et
al. (ScbSO), suggests the ratio is good within a factor of plus or
minus three.
To estimate the hazard level of a pile, the calculation must
consider not only soil concentrations, but also the uptake of elements
from soil by crops. Investigators at Oak Ridge National Laboratory
have been developing transfer factors for soil/plant uptake (i.e., the
ratio of ppm of an element in plant tissue to ppm of the element in
soil) as a function of element. Two transfer factors have been
described:
1. by, for uptake in vegetative (e.g., stems and leaves)
portions of plants,
2. br, for uptake in the reproductive and storage portions
(e.g., fruits and tubers) of plants (BaaSl).
In addition, the total quantity of vegetative and reproductive
portions of plants will vary with diet and age of persons eating them.
This also must be considered. Rupp has developed estimates of
age-specific average daily intakes of foods (Ru80). Her estimates can
be used to group foods by age for the two factors bv and br (Table
C-10) .
C-19
-------
TABLE C-10. ESTIMATED AVERAGE DAILY INTAKE OF FOODS
BY SELECTED AGE GROUPS
(a)
(in grams;
Age Group
Food Uptake Class 1 yr 1-11 yrs 12-18 yrs >18 yrs
Potatoes (br) 6 49 67 69 65
Vegetables:
Deep Yellow (b ) 12 7 788
Legumes (br) 12 22 28 25 25
Leafy (bv) 2 20 30 50 43
Other (b,7) 50 58 82 99 90
v'
Fruit:
Citrus, Tomato (br) 23 74 93 99 93
Other (br) 112 112 116 87 94
Dry (br) 32 111
Grain (br) 21 87 113 97 96
Nuts,
Nut Butter (br) 2 9 10 5 6
243 440 547 540 521
Total
bv
br
52
191
78
362
112
435
149
391
133
388
from Rupp (Ru80).
(b)dasses from Baes, et al. (BaaSl):
bv, for uptake in vegetative portions of plants.
br, for uptake in reproductive and storage portion of plants.
Age-weighted average using weights of 1/71, 11/71, 7/71, and 52/71
for each age group.
Using the uptake factors by and br, we can estimate the
concentration of elements in soil that will produce an elemental
concentration of 1 ppm (100 ug/lOOg air-dried weight of food) in the
components of a locally grown diet (Table C-ll). The estimated soil
concentrations for 1 ppm of elemental uptake calculated on an air-dried
weight basis can be converted,to soil concentrations yielding 1 ppm of
an element in fresh food crops (Sh = soil concentration in ppm
yielding 1 ppm in air-dried crops consumed by humans) and forage crops
(Sa = soil concentration in ppm yielding 1 ppm in air-dried crops
consumed by animals). This assumes the air-dried weight is 25 percent
C-20
-------
of the fresh weight (BaaSl). These soil concentrations, yielding 1 ppm
of an element in food crops, are compared (Table C-12) with:
1. The concentrations that, in a 500-gram diet (25 percent bv
vegetative, 75 percent br reproductive crops), would yield a
daily intake equal to the limit of Safe and Adequate Intakes
recommended by the National Academy of Sciences and
concentrations that would yield a potentially toxic intake as
estimated from data published by the National Academy of
Sciences.
2. Those potentially toxic (in the case of forage crops)
concentrations in the livestock rations. The uncertainty in
the intake leading to chronic toxicity is reflected in the
range of estimates for some elements.
Using values in Table C-12 and Table 3-2, we can estimate the
potential land contamination around each pile that would produce crops
that are hazardous to man and animal. For example, the Slick Rock (NC),
Colorado, site may be contaminated with hazardous levels of lead out to
the 28-pCi/g radium 226 contour if the hazardous soil concentration of
lead is considered to be 45 ppm. Mercury levels may be hazardous out
to the 45-pCi/g radium-226 contour.
Similar analyses could be developed when contaminated water is
used to irrigate crops. In any case, the potential hazard associated
with uncovered inactive tailings should be evaluated on a site-specific
basis. The analysis should consider not only radioactive, but also
stable elements in tailings and food or feed and water pathways.
C.5. Plants and Animals on Tailings Piles
Plants
Plants growing on tailings piles may take up elements from the
tailings. Uptake of radioactive and other elements from tailings has
been reported by several investigators (Dr78, Dr79, Mo77). Although
uptake can produce appreciable concentrations of radionuclides in
plants growing on tailings, there does not seem to be any radioisotope
bioconcentration, i.e., the concentration in vegetation does not exceed
the concentration in the tailings (Dr78, Dr79, Mo77). For example,
radium-226 concentration in vegetation is usually 0.03 of that in
tailings or less (Dr79, Mo77). However, in some species of vegetation,
the radium-226 concentration has been as high as 0.25 or 0.30 of that
in the tailings (Dr79).
In the case of most elements, the concentration is from 0.0006 to
0.40 of that of the tailings (Dr78, Dr79). However, some elements are
bioconcentrated; i.e., nickel, selenium, molybdenum, arsenic, which
attain concentrations 1 to 10 times that in the tailings (Dr78, Dr79).
Animals consuming such vegetation may be protected to some extent,
C-21
-------
TABLE C-ll. ESTIMATED CONCENTRATION OF ELEMENTS IN SOIL THAT WILL
PRODUCE A CONCENTRATION OF 1 ppm IN CROPS
Element
Arsenic
Barium
Boron
Cadmium
Chromium
Copper
Iron
Lead
Manganese
Mercury
Molybdenum
Nickel
Selenium
Silver
Tin
Vanadium
Zinc
Transfer Factor
(x 10~3)
bv
40
150
4000
550
7.5
400
4.0
45
250
900
250
60
25
400
30
5.5
1500
br
6.0
15
2000
150
4.5
250
1.0
9.0
50
200
60
60
25
100
6.0
3.0
900
e
15
49
2500
250
5.3
290
1.8
18
100
380
110
60
25
180
12
3.6
1100
Soil Concentration (ppm)
Yielding 1 ppm in
Air Dried Crop
Food(b)
Sh
67
20
0.40
4.0
190
3.4
560
56
10
2.6
9.1
17
40
5.6
83
280
0.91
Forage^
S
a
25
6.7
0.25
1.8
130
2.5
250
22
4.0
1.1
4.0
17
40
2.5
33
180
0.67
(a)be = 0.255 bv + 0.745 br.
b = vegetative portions of plants
b = reproductive and storage portions of plants
(b).
'Crops used in human diet:
(c.)
vv-'
Sh ~ so*^ concentrati°n (ppm) that yields 1 ppm in crops consumed by
humans .
Crops used to feed livestock:
sa = soil concentration (ppm) that yields 1 ppm in crops consumed by
animals.
C-22
-------
TABLE C-12. SOIL CONCENTRATIONS OF ELEMENTS THAT MIGHT BE ASSOCIATED
WITH TOXIC CONCENTRATIONS IN THE FOOD PATHWAY
Soil<<3)
Concentration
for Potentially
Element
Arsenic
Boron
Barium
Cadmium
Chromium
Copper
Iron
Lead
Manganese
Mercury
Molybdenum
Nickel
Selenium
Silver
Tin
Vanadium
Soil Concentration
Yielding 1 ppm
(1 ug/g) Wet Wt. (a>
sh
sa
sh
sa
sh
sa
sh
sa
Sh
sa
sn
Sa
Sh
sa
Sh
Sa
sh
sa
Sh
sa
sh
Sa
sa
sh
Sa
Sh
sa
sh
sa
sh
Sa
268
100
2.5
1.0
80
26.8
16
7.2
3960
520
13.6
10
2240
1000
224
88
40
16
10.4
4.4
36.4
16
68
68
160
160
22.4
10
332
132
1120
720
Concentrations'"' Human'c) Safe
(ppm) in Ration Adequate & Human
Toxic to Livestock Safe Intake Intake
Ruminants Nonruminants (ug/d)
- 50
_
_
_
_
_
_
_
200
- - -
3000
100-500 250-1600
18000
- - -
- - -
300 80
5000
400-700 500+
_
- - -
500
5-100 200-4000
- 50
_
200
4-10 7-15
_
_
_
- - -
- 25
20 (Young) 35+
(ppm)
26.8
-
-
-
-
-
-
-
1580
-
82
-
80640
-
-
-
400
-
-
-
36.4
-
6.8
-
64
-
-
-
-
-
56
Toxic
Human
Intake
(ppm)
322 to 1610
-
5000+
-
16000+
-
19.2
-
79200
-
41 to 6800
-
N/A
-
44.8 to 1434
-
1600
-
6.24
-
728 to 1092
-
760
-
224 to 22400
-
9.0
-
9960 to 43160
-
22400
'^Calculated from Table C-ll on the basis of: Air Dry Weight = 0.25 Wet Weight.
From Table C-5.
'c>From Table C-4.
(d>Calculated on the basis of data in NAS80.
- (No data).
C-23
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since the major concentration may occur in the roots of the plants
(Chb79). However, the biological availability of the elements may be
changed by incorporation into the plants (Ti77). The extent to which
this occurs and the consequences are unknown.
For a few plants, whether the tailings are covered or uncovered
may be moot. Whicker (Wh78) cites reports that many of the species of
grasses and forbs of the Great Plains have root systems that penetrate
to 2 to 5 meters; 50 percent of the plains and prairies species
penetrate 5 to 7 meters and some desert basin plants 2 to 3 meters.
Depending on cover depth and erosion rates, even covered tailings may
be accessible to the roots of plants growing over them.
Such root penetration should not cause a major problem, since
potentially affected areas are small (See Table 3-6) and, even if
access is not restricted, these plants will not be the only source of
food for the animals. In addition, as the roots enter zones of higher
element concentrations, the root uptake should decrease. Barber and
Claassen (Bab77) have reported that the root uptake-soil concentration
relationship was curvilinear, asymtoticly reaching a maximum total
uptake as soil concentration increases; i.e., the uptake fraction
decreases as soil concentration increases.
Animals
Small burrowing and other animals may penetrate covered and
uncovered tailings. Whicker (Wh78) cites reports showing that most
burrowing animals confine their activity to the top meter of soil,
although the Great Basin pocket mouse (Perognathus parvus) may burrow
to a depth of 2 meters and harvester ants (Pogonomyrmex occidentalis)
may go to a depth of over 3 meters. There are no data on elemental
poisoning in these animals.
C-24
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ANNEX 1
TOXICOLOGY OF SELECTED ELEMENTS
FOLLOWING ORAL ADMINISTRATION
-------
ARSENIC
Arsenic is a metal which is perhaps, but not yet proven, essential
to human nutrition (NAS80). It is widely distributed in nature and
used extensively in medicine and agriculture. The pentavalent form
(As+5) is less toxic than the trivalent form (As+3), but usually
more teratogenic*1) (Ve78). Twenty-three milligrams of arsenic taken
as arsenic trioxide have been fatal (Jo63).
Chronic arsenic poisoning produces skin abnormalities,
proteinuria, anemia, and swelling of the liver. Some cardiac and
nervous disorders have been observed in Japan among persons drinking
well water containing 1 to 3 ppm of arsenic (Te60) . Epidemiologic
studies of chronic arsenic poisoning in Antofagasta, Chile, found a
high incidence of skin and cardiovascular abnormalities, chronic coryza
and abdominal pain, and some chronic diarrhea in children who drank
water containing 0.6 to 0.8 ppm of arsenic (NAS77). The incidence of
skin lesions decreased by a factor of about 16 when the arsenic content
of the water was decreased to 0.08 ppm (NAS77), but the effects did not
disappear completely.
Chronic consumption of arsenic has also been associated with
increased incidence of lung cancer (Ve78) and skin cancer (Ve78, NAS77,
God77). Another epidemiologic study of chronic arsenic poisoning in
Taipei found skin cancer, hyperpigmentation, keratosis and blackfoot
disease (peripheral arteriolar disorder leading to gangrene of
extremities, especially the feet) with prevalence of 1.6, 18.3, 7.1 and
0.89 percent, respectively, in persons drinking well water containing
arsenic (Ye73). The prevalence of skin cancer, hyperpigmentation and
keratosis increased with age. Hyperpigmentation developed after at
least a 5-year exposure to the arsenic in water, keratosis after at
least 14 years and skin cancer after at least 20 years (Ts77). The
concentration of arsenic in well water used by these people ranged from
about 20 to 1100 micrograms per liter (Ts77).
BARIUM
Barium is another metal apparently not essential to human
nutrition. It is widely distributed in nature and used in industry,
medicine, and agriculture. Consumption of 550 to 600 milligrams of
barium as barium chloride has been reported to be fatal (So57).
Acute toxic doses of ingested barium cause abnormal muscle
stimulation due to induced release of catacholamines from the adrenal
medulla. This may be accompanied by salivation, vomiting, violent
diarrhea, high blood pressure, hemorrhage into organs, and muscular
(Dleratogenicity is the capability to cause abnormal fetal development.
C-27
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paralysis. There is, however, no evidence of chronic toxicity from
long-term consumption of barium in humans or in animals (NAS77, Un77).
BORON
Boron is a minor element in the environment, extracted primarily
from evaporated deposits in a few borax lakes. It may be released in
volcanic gases or dissolved from deposits by water and transported as
boric acid or as a borate. Boron is an essential element for plants,
but it does not seem to be essential for animals (Un77). Although
boron is essential for plants, it is also toxic. Some crops are
sensitive to concentrations greater than or equal to 1.0 ppm of boron
in irrigation water (NAS72a).
Acute poisoning has occurred from boric acid and borax, usually
accidentally. The fatal dose of boric acid is around 3 to 6 grams in
infants and 15 to 20 grams in adults (Goa54, Gob65), and for borax
around 25 to 30 grams (Goa54). The first symptoms are nausea,
vomiting, and diarrhea followed by a drop in body temperature, skin
rash, headache, depression of respiratory centers, cyanosis, and
circulatory collapse. Death may occur in hours or a few days.
No chronic toxicity from boron compounds has been reported.
Gastrointestinal and pulmonary disorders have been reported in lambs
grazing on pastures with high boron concentrations and drinking water
containing 0.2 to 2.2 ppm boron. However, mice, given 5 ppm boron in
drinking water during lifetime studies, showed no effects (Un77).
Human diets normally supply 2 to 4 mg boron per day, but since
boron occurs in higher concentrations in foods of plant origin, people
consuming large quantities of fruits and vegetables may have daily
boron intakes of 10 to 20 milligrams (Un77).
CADMIUM
Cadmium is a metal distributed in the environment in trace
quantities, except in some zinc, copper, and other ores. It is not
essential to human nutrition and is used mainly in industry. Acute
fatal poisoning with cadmium is rare because cadmium salts cause
vomiting when consumed. Acute poisoning from consuming food or drink
contaminated with cadmium occurs 15 to 30 minutes after swallowing 15
to 30 milligrams of cadmium (EPA79). Symptoms include continuous
vomiting, salivation, choking sensations, abdominal pain, and
diarrhea. Acute toxicity symptoms have been reported in school
children eating popsicles containing 13 to 15 ppm (EPA79).
Absorbed cadmium is toxic to all body organs, damaging cells and
enzyme systems. It is bound tightly in the body, and little is
excreted, so it accumulates over the lifetime. In Japan, among people
who consumed about 0.6 milligrams of cadmium per day, chronic toxicity
was reported (EPA76). The illness was called "Itai-itai" disease and
C-28
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resulted in bone and kidney damage. Symptoms were seen mostly in older
women whose diets were lacking in protein and calcium (Un77, NAS77).
Since cadmium toxicity is moderated by calcium, zinc, copper, manganese
(Un77), selenium, iron, vitamin C, and protein (God77), diet is an
important factor in cadmium poisoning.
The earliest symptom of chronic cadmium toxicity is kidney damage,
evidenced by increased protein in the urine. This occurs when the
cadmium level in the renal cortex reaches 200 to 300 ppm of wet weight
(EPA76, EPA79). This 200-ppm level can be reached after consuming
about 350 micrograms of cadmium a day for 50 years (EPA76). Con-
sumption of only 60 micrograms a day has been estimated to cause kidney
damage in 1 percent of the exposed group (EPA79). The body retains as
much cadmium from smoking one pack of cigarettes per day as from
ingesting 25 micrograms of cadmium a day (EPA79).
High levels of cadmium have caused reproductive disturbances and
teratogenesis in experimental animals (Ve78, Un77, EPA79, NAS77). It
has also been implicated in human hypertension, cardiac problems, and
prostatic carcinogenesis (Un77, EPA79, God77, NAS77), but the
connection is not well defined. However, a well-defined pathology in
heart, liver and kidneys of animals fed 5 ppm of cadmium in their diet
has been established (Ko78).
CHROMIUM
Chromium (Cr~") is a metal that is essential to human nutrition;
it is involved in glucose and lipid metabolism and protein synthesis
(Un77). It is widely distributed in.nature and has many industrial
applications. Oral toxicity is low; humans can tolerate 500 milligrams
daily of chromic sesquioxide (Ve78). Hexavalent chromium (Cr+°) is
much more toxic than trivalent (Cr+3) (Un77, NAS80, Ve78). The
principal damage in acute chromium poisoning is tubular necrosis in the
kidney. Large enough doses of hexavalent chromium can cause
gastrointestinal tract hemorrhaging, but lifetime exposure of
laboratory animals to less than 5 ppm of chromium in drinking water
caused no reported effects (NAS77, Un77).
No information exists on the effects of chronic chromium
consumption by humans. Skin hypersensitivity to chromium has been
reported to be second only to nickel hypersensitivity as the most
common form of skin sensitization in some studies (Ka78).
COPPER
Copper is widely distributed in nature. Its principal uses are
industrial, especially electrical. It is an essential element in human
nutrition.
The prompt emetic action of copper salts tends to limit their
acute toxicity. However, copper is occasionally leached into acidic
C-29
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beverages. Symptoms of toxicity following ingestion (cramps, vomiting,
and diarrhea) usually occur in 10 to 90 minutes and last less than 24
hours (Ve78). Copper is usually more toxic in drink than in food. In
infants, 7 ppm of copper is fatal (Ve78). In adults, 175 to 250
milligrams of copper taken as copper sulfate may be fatal (Ve78).
Persons with Wilson's disease, a disorder of copper metabolism,
and persons with glucose-6-phosphate dehydrogenase defficiency may be
abnormally sensitive to chronic copper poisoning (Ve78). Persons with
Wilson's disease may be adversely affected by consumption of about 1.5
milligrams of copper a day (NAS80).
CYANIDE
Cyanide is composed of carbon and nitrogen (CN). The most toxic
forms of cyanide are hydrogen cyanide (HCN) and free cyanide ions
(CN~). It is not essential to human nutrition and is used or formed
in many industrial processes and used in agriculture.
Consumption of 50 to 200 milligrams of cyanide or its salts causes
death in 50 percent of those exposed (Goc76). Death usually occurs
within 1 hour. Cyanide interferes with the essential enzyme cytochrome
C oxidase. This enzyme is required by all cells using oxygen,
particularly those in the brain and heart. However, there is no
chronic or cumulative toxicity, since the adult body can convert doses
of 10 milligrams or less to the much less toxic thiocyanate ion and
excrete it (EPA76).
IRON
Iron, a metal essential for human nutrition, is involved in oxygen
transport and enzyme systems. The element is very widely distributed
in nature and has medical, agricultural, and industrial applications.
Ingestion of 40 to 590 milligrams of iron per kilogram of body weight
as FeS04 has been fatal (Ve78); however, intakes of 25 to 75
milligrams per day have been cited as safe (Un77). Toxic doses of
iron, e.g., 100+ milligrams per kilogram, can cause liver and
gastrointestinal tract damage, hypotension, prostration, and peripheral
cardiac failure (Ve78).
There are no reports of chronic toxicity due to iron ingested by
animals or humans in the United States. Consumption of 200 mg of
soluble iron per day has caused siderosis in malnourished Bantus in
South Africa (Un77).
LEAD
Lead is a metal widely distributed in nature and used extensively
in industry and agriculture; it is not essential to human nutrition.
The amount of lead absorbed before symptoms of toxicity appear is
rarely known; however, one man ingested 3.2 milligrams per day for 2
years before symptoms occurred (NAS72a).
C-30
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Toxicity is usually related to levels of lead in the blood. A
level of 3.3 ppm in blood has been associated with acute brain
pathology and death in children (NAS72a). Levels of 0.8 ppm and
greater have been associated with brain, peripheral nervous system, and
kidney pathology and severe colic, seizures, paralysis, blindness, and
ataxia in children (NAS72a, God77, NAS77, Un77). Subclinical (hard to
detect because clinical symptoms are lacking) effects on the central
nervous system, red blood cells, kidneys, and enzymes may occur at
levels of 0.4 to 0.8 ppm in blood (God77). In women and children some
changes in red cells can be detected at 0.25 to 0.3 ppm in blood
(NAS77).
Continued drinking of water containing 0.1 ppm could produce lead
levels of 0.25 to 0.4 ppm in blood (Un77, NAS77). Such exposure could
contribute to clinical lead poisoning, particularly in children (NAS77).
MANGANESE
Manganese is a metal widely distributed in nature. It is used
extensively in industry, but infrequently in medicine. It is essential
to human health. Toxicity is related to its valence state, probably
through solubility. Mn2+ is more toxic than Mn^*, and higher
oxides are more toxic than lower oxides (Ve78).
Most chronic manganese toxicity is related to industrial
exposure. Metal fume fever, a pulmonary pneumonitis, may result from a
few months inhalation of manganese oxide fumes at concentrations of
1000 ppm or greater depending on the oxidation state of the manganese
and the chemical compound involved (Ve78). Chronic manganese toxicity
can occur following inhalation or ingestion for 6 months to 2 years.
"Manganism", the condition that results, is characterized by a severe
psychiatric disorder resembling schizophrenia and is followed by a
permanently crippling neurological disorder clinically similar to
Parkinson's disease (Un77). There are degenerative changes in the
brain, liver, and kidneys (Ve78). The condition appears to be
irreversible (Un77, Ve78).
Normal dietary intakes of 3 to 7 milligrams per day (NAS77) or 8
to 9 milligrams per day (NAS80) have been considered safe. However,
there is a report of manganism with neurological symptoms and death in
two patients (one suicide case) in a Japanese incident where 16 persons
were exposed to manganese and zinc in drinking water. While the
duration of exposure and amount of water consumed are not known, the
water contained 14 ppm of manganese and the estimated daily intake was
20 milligrams (NAS80).
MERCURY
Mercury is a metal not essential to human nutrition. It is
distributed in nature as a trace element, except in some metal ores,
and has many industrial applications. Consumption of 158 milligrams of
mercury as mercuric iodide has been reported to be fatal (Ve78). Acute
C-31
-------
effects of nonfatal doses of mercury salts include local irritation,
coagulation and necrosis of tissue, kidney damage, colitis,
hallucinations, and a metallic taste in the mouth.
As is the case with lead, chronic mercury poisoning develops
slowly. Many of the symptoms relate to the nervous system: impaired
walking, speech, hearing, vision, or chewing and insomnia, anxiety,
mental disturbances, and ataxia. There also may be damage to kidneys,
blood cells, and the gastrointestinal tract, and enzyme systems (NAS77,
Ve78). Studies of Minamata disease (methyl mercury poisoning) suggest
that consumption of 1 milligram of mercury per day as methyl mercury
over a period of several weeks will be fatal (Ve78); consumption of 0.3
milligrams per day will cause clinical symptoms of mercury poisoning
(Un77, NAS77). About 10 times as much methyl mercury would be absorbed
as inorganic mercury (God77).
Mercury passes through the placenta. It has caused cases of
Minamata disease through fetal exposure (NAS77) and may cause birth
defects (Ve78, Un77).
MOLYBDENUM
Molybdenum is a metal essential in trace quantities for human
nutrition. It is present in nature in trace quantities, except in some
ores. It has been widely used in industry. There are no data for
acute toxicity of molybdenum following ingestion by humans, but the
animal data (Ve78) show that toxicity results from intakes of around
hundreds of milligrams per kilogram of body weight.
Chronic toxicity symptoms have been reported in 18 percent to
31 percent of a group of Armenian adults who consumed 10 to 15
milligrams of molybdenum per day and in 1 percent to 4 percent of a
group consuming 1 to 2 milligrams of molybdenum per day (Cha79,
NAS80). Clinical signs of the toxicity were a high incidence of a
gout-like disease with arthralgia and joint deformities, and increased
urinary excretion of copper and uric acid. Increased urinary copper
excretion has been observed in persons who consumed 0.5 to 1.5
milligrams of molybdenum per day and in persons drinking water
containing 0.15 to 0.20 ppm of molybdenum but not in persons drinking
water containing up to 0.05 ppm of molybdenum (Cha79). The
significance of the increased copper excretion is not known.
Recent reports have associated molybdenum deficiency and
esophageal cancer (Lub80a,b). Until these reports are confirmed and
evaluated, the minimum molybdenum requirements are uncertain.
NICKEL
Nickel is an element widely distributed in the environment and is
used mostly for industrial purposes. It is essential in animal
nutrition and perhaps for humans (NAS80). Oral toxicity is low, with
C-32
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most of the effect due to gastrointestinal irritation (NAS80).
Extrapolation from animal studies suggests a daily oral dose of 250
milligrams of soluble nickel would produce toxic symptoms in man (NAS
80) .
Inhalation of nickel carbonyl has caused severe toxicity in man
and inhalation of nickel fumes with concentrations of the order of 0.08
to 1.2 ppm has led to lung cancer, errosion of nasal mucosa/ and other
problems (HEW77). Contact dermatitis related to nickel exposure has
been reported, often with about 12 percent of people sensitive to
cutaneously applied nickel (God77). An oral dose of 5.6 milligrams of
nickel (as NiSO^j) can produce a positive reaction in nickel-sensitive
persons within 1 to 20 hours (NAS80).
NITRATE
Niflfcate, an anion of nitrogen and oxygen (NO,)» is the most
stable form of combined nitrogen in oxygenated water. All nitrogenous
materials in natural waters tend to be converted to nitrates (NAS77).
The fatal dose has been estimated as 120 to 600 milligrams of nitrate (27
to 136 milligrams of nitrate-nitrogen) per kilogram of body weight
(Bua61). Burden estimated the maximum permissible dose of
nitrate-nitrogen as 12 milligrams in a 3-kilogram infant and 240
milligrams in a 60-kilogram adult (Bua61). Nitrate is converted to
nitrite in the gastrointestinal tract, and the absorbed nitrite causes
the toxicity, in this case methenoglobinemia (NAS72b, NAS77).
Chronic toxicity is usually observed in children. Symptoms of
toxicity have been reported in children drinking water with 11 ppm of
nitrate-nitrogen but not in those consuming 9 ppm or less (NAS72b,
NAS77). Nitrates can be reduced to nitrites and combined with secondary
amines or amides to form N-nitroso compounds, which are considered
carcinogens (NAS72b, NAS77).
RADIUM
Radium is a metal widely distributed in the environment in trace
quantitities, except in some ores. It is not essential to human
nutrition. It was widely used in industry and medicine. No reliable
data exist on acute radium toxicity in humans (Si45), and chemical
toxicity, if any, is expected to be masked by radiation damage
(Ve78,Shc74). Sharpe (Shc74) reported increases in assessory sinus and
bronchial cancer and possible increases in other malignant cancers; blood
ayscrasias and bone damage in former radium dial painters.
Chronic intake of radium is expected to be carcinogenic, especially
in bone. Radium isotopes are expected to have roughly the same chronic
toxicity per unit of activity (picocurie) consumed, but not per unit of
weight (microgram) consumed (IP79). Radium-227, which is 1,000 to 10,000
times less radio-toxic than other radium isotopes (IP79), may be an
exception.
C-33
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Consuming one plcocurie of radium per day continuously entails a-
lifetime risk of developing a radiation-induced cancer of about two
chances in a million per year of radium consumption (Su81).
SELENIUM
Selenium, a metal, is widely but unevenly distributed in nature.
It is essential in human nutrition in trace amounts (NAS77) and is used
in industry and medicine.
Drinking water containing 9 ppm of selenium for a 3-month period
caused symptoms of selenium toxicity: lethargy, loss of hair, and loss
of mental alertness (EPA76). Other symptoms of selenium toxicity
include garlicky breath, depression, dermatitis, nervousness,
gastrointestinal disturbance, and skin discoloration (EPA76, NAS77).
Consumption of 1 milligram per kilogram of body weight per day may
cause chronic selenium poisoning (God77). Bad teeth, gastrointestinal
disturbances, and skin discoloration have been associated with
consumption of 0.01 to 0.1 milligram of selenium per kilogram of body
weight per day (EPA76).
Selenium has also been suspected of causing increased
teratogenesis and dental caries, but there are little data on these
aspects of selenium toxicity (Ve78). Selenium has been reported to
increase tumors in some animal models and have antitumor activity in
other animal models (NAS77). It has also been reported that there is
an inverse relationship between the level of selenium intake in humans
and the age-specific death rates of specific heart diseases (ShbSO).
Additional studies are needed to illuminate the role of selenium in
these reports.
SILVER
Silver is a metal distributed in trace levels in the environment,
except in some ores. It is not essential to human nutrition and is
widely used in industry, medicine, photography, and art. Data on acute
toxicity in people are sparse, but consumption of 140 milligrams of
silver nitrate causes severe gastroenteritis, diarrhea, spasms, and
paralysis leading to death (Ve78).
Chronic toxicity from soluble silver salts is usually associated
with argyria, a permanent blue-grey discoloration of the skin caused by
deposited silver (EPA76, NAS77). Silver deposited in tissue,
especially in the skin, apparently is retained there indefinitely
(EPA76), perhaps as a harmless silver-protein complex or as silver
sulfide or selenide (Ve78). If 1 gram of accumulated silver causes
borderline argyria as postulated by the National Academy of Sciences,
this level would be reached after 50 years of drinking water containing
0.05 ppm of silver or after 91 years at 0.03 ppm (NAS77). Prolonged
consumption of silver salts may also cause liver and kidney damage and
changes in blood cells (Ve78).
C-34
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THORIUM
Thorium is a metal distributed in the environment in trace
quantities, except in some ores. It is not essential to human
nutrition and is used in industry. It was formerly used in medicine.
There are no data on oral toxicity in humans. In animal studies,
thorium given orally at levels of about a gram per kilogram of body
weight caused death in some of the animals (Ve78, So07).
Chronic toxicity appears limited to carcinogenesis associated with
the radioactivity of the thorium. The various isotopes of thorium are
expected to vary greatly in toxicity, considered on a per-unit-activity
basis (IP79); all are expected to produce radiation-related cancers.
URANIUM
Uranium is a metal widely distributed in the environment in trace
quantities. It is not essential to human nutrition and is used
primarily in the nuclear power industry.
Acute toxicity from a single uranium exposure in humans has been
estimated to occur, based on kidney damage, following absorption of
0.1 milligram per kilogram of body weight; some deaths would be
expected following absorption of 1 milligram per kilogram of body
weight (Lua58). If 20 percent of the uranium in water is absorbed by a
70-kilogram man, kidney damage could be expected following consumption
of 2 liters of water containing 17.5 milligrams per liter, and death
could result from consumption of water containing 175 milligrams per
liter of uranium. This is consistent with observations that oral doses
of 10.8 milligrams of uranium (as uranyl nitrate hexahydrate)
apparently caused no kidney damage (Hu69). However, consumption of 470
milligrams of uranium (1 gram of uranyl nitrate) caused vomiting,
diarrhea, and some albuminuria (Bub55).
Building up a tolerance to uranium is apparently possible.
Uranium nitrate was used to treat diabetes and various urinary problems
by homeopathic physicians, usually reporting no untoward side effects
(Sp68, Ho73). Spoor (Sp68) cites reports, from the medical literature
of the 1890's, of cases in which uranyl nitrate was used to treat
diabetes, starting with a conditioning dose of about 60 milligrams of
uranyl nitrate three times a day after meals and gradually raising the
daily dose over a period of a few weeks to 3 grams, or 6 grams in one
case. If such doses were given without conditioning, they would be
expected to be fatal.
Chronic toxicity may also be related to enzyme poisoning in the
kidneys (Lua58), with some liver damage as a result of the kidney
damage (Ve78). Experiments with animals that inhaled uranium compounds
for a year showed mild kidney changes associated with deposition of
about 1 microgram of uranium per gram of kidney. Extending these
C-35
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results, tor a human kidney weight of 300 grams, absorption of 20
percent of uranium in water and deposition of 11 percent of absorbed
uranium in the kidney and retained with a 15-day half-life (Sp73),
chronic chemical toxicity could develop in humans who drink water
containing about 0.315 ppm of uranium.
Uranium can also cause chronic toxicity in the form of radiation-
related carcinogenesis (Du75, Fia78). The various uranium isotopes
vary greatly in their carcinogenic potentials, as considered on a unit
activity basis (IP79). There is some question as to whether
radiation-related cancer or chemical toxicity would be the major
response to some uranium isotopes (Ad74).
VANADIUM
Vanadium is a metal widely distributed at low concentrations in
nature. It is not known to be essential to human nutrition, although
it is in some animals (NAS80). Vanadium salts are not very toxic when
given orally (Wa77). The lethal dose has been estimated as 30 mg of
V205 (16.8 mg V) introduced into the blood in soluble form (Wa77).
Gastrointestinal absorption has been estimated as 0.1 percent to 1.0
percent of soluble vanadium compounds (Wa77). So, the lethal dose of
soluble vanadium given orally, might range from 1,700 to 17,000
milligrams.
Chronic toxicity resulting from oral exposure to vanadium has not
been reported. In human studies, 4.5 milligrams of vanadium per day
given as oxytartarovandate caused no symptoms over a 16-month period
(Un77). However, if animal studies can be extrapolated to man, daily
oral administration of 10 milligrams of vanadium or more may cause
chronic toxicity (NAS80).
C-36
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APPENDIX C
REFERENCES
Ad74 Adams N. and Spoor N.L., "Kidney and Bone Retention Functions
in the Human Metabolism of Uranium," Phys. Med. Biol.
19:460-471, 1971.
Baa81 Baes C.F., Sharp R.D., Sjorien A.L. and Shor R.W., A Review
and Analysis of Parameters for Assessing Transport of
Environmentally Released Radionuclides Through Agriculture,
ORNL-5786. Oak Ridge National Laboratory, Tennessee, 1981.
Bab77 Barber S.A. and Claassen N., "A Mathematical Model to Simulate
Metal Uptake by Plants Growing in Soil," in: Biological
implications of Metals in the Environment, pp. 358-364, ERDA
Symposium Series 42, Energy Research and Development
Administration, Washington, 1977.
Bo66 Bowen H.J.M., Trace Elements in Biochemistry, Academic
Press, New York, 1966.
Bua61 Burden E.H.W.J., "The Toxicology of Nitrates and Nitrites with
Particular Reference to the Potability of Water Supplies,"
Analyst 86:429-433, 1961.
Bub55 Butterworth A. "The Significance and Value of Uranium in Urine
Analysis," Trans. Ass. indstr. Med. Offrs. 5:36-43, 1955.
Caa80 Calabrese E.J., Moore G.S., Tuthill R.W. and Sieger T.L.,
editors. "Drinking Water and Cardiovascular Disease," J.Env.
pathol. Toxicol. 4(2,3), pp. 1-326, 1980.
Cab77 Cargo D.N. and Mallory B.F., Man and His Geologic
Environment. 2nd Edition. Addison-Wesley Publishing Co.,
Reading, Mass., 1977.
Cha79 Chappell W.R., et al., Human Health Effects of Molybdenum in
Drinking Water, EPA-600/1-79-006, USEPA, Health Effects
Research Laboratory, Research Triangle Park, N.C., 1979.
Chb79 Cherry D.S. and Guthrie R.K., "The Uptake of Chemical Elements
from Coal Ash and Settling Basin Effluent by Primary
Producers, II. Relation Between Concentrations of Ash
Deposits and Tissues of Grasses Growing on the Ash," Sci.
Total Environ 13:27-31, 1979.
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REFERENCES (Continued)
Chc68-69 Christiansen G.A. and Jacobson G.A., Report on Molybdenosis in
Farm Animals and its Relationship to a uraniferous Lignite
Ashing plant, Environmental Control, Div. of Environmental
Engineering, North Dakota State Department of Health, Bismarck,
1968-69.
Doa72 Dollahite J.W., et al., "Copper Deficiency and Molybdenosis
Intoxication Associated with Grazing Near a Uranium Mine,"
Southwest Vet., pp. 47-50, Fall 1972.
Dob75 Douglas R.L. and Hans J.M. Jr., Gamma Radiation Surveys at
inactive uranium Mill Sites, Technical Note ORP/LV-75-5, Office
of Radiation Programs-Las Vegas Facility, USEPA, Las Vegas,
Nevada, 1975.
Dr78 Dreesen D.R., Marple M.L., and Kelley N.E., "Contaminant
Transport, Revegetation, and Trace Element Studies at Inactive
Uranium Mill Tailings Piles," in: proceedings of the Symposium
on uranium Mill Tailings Management, pp. 111-139, Colorado
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Dr79 Dreesen D.R. and Marple M.L., "Uptake of Trace Elements and
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C-41
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Sca73
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
•E§A°W4-82-013-l
2.
3. RECIPIENT'S ACCESSION NO.
.TITLE AND SUBTITLE _ _ . . ,
Final Environmental Impact Statement for Remedial
Action Standards for Inactive Uranium Processing
Sites (40 CFR 192), Volume I
5. REPORT DATE
October 1982
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Radiation Programs (ANR-460)
401 M Street, S.W.
Washington, B.C. 20460
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The Environmental Protection Agency is issuing final standards for the long-term
control of tailings piles at inactive uranium processing sites and for cleanup of
contaminated open land and buildings. These standards apply to tailings at locations
that qualify for remedial actions under Title I of Public Law 95-604, the Uranium
Mill Tailings Radiation Control Act of 1978. This Act requires EPA to promulgate
standards to protect the environment and public health and safety from radioactive
and nonradioactive hazards posed by residual radioactive materials at the twenty-
two uranium mill tailings sites designated in the Act and at additional sites where
these materials are deposited that may be designated by the Secretary of the Depart-
ment of Energy. The Final Environmental Impact Statement (Volume I) examines health,
technical considerations, costs, and other factors relevant to determining standards.
Volume II contains EPA's responses to comments on the proposed standards and the
Draft Environmental Impact Statement (EPA 520/4-80-011).
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. cos AT I Field/Group
uranium mill tailings
inactive uranium mill sites
radioactive waste disposal
radon
radium-226
Uranium Mill Tailings Radiation Control
Act of 1978
18. DISTRIBUTION STATEMENT
Release unlimited.
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
266
20. SJECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
•D.S. GOTORHMENT P
omoE . 1982
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