EPA530-R-94-032
NTIS PB94-200987
TECHNICAL RESOURCE DOCUMENT
EXTRACTION AND BENEFICIATION OF
ORES AND MINERALS
VOLUME 5
URANIUM
December 1994
U.S. Environmental Protection Agency
Office of Solid Waste
Special Waste Branch
401 M Street, SW
Washington, DC 20460
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Technical Resource Document: Uranium
DISCLAIMER AND ACKNOWLEDGEMENTS
This document was prepared by the U.S. Environmental Protection
Agency (EPA). The mention of company or product names is not to
be considered an endorsement by the U.S. Government or the EPA.
This Technical Resource Document was distributed for review to the
U.S. Department of the Interior's Bureau of Mines, the Western
Governors Association, the Interstate Mining Compact Commission,
the American Mining Congress, and Public Interest Groups. EPA is
grateful to all individuals who took the time to review sections of this
Technical Resource Document.
The use of the terms "extraction," "beneficiation," and "mineral
processing" in the Profile section of this document is not intended to
classify any waste streams for the purposes of regulatory interpretation
or application. Rather, these terms are used in the context of common
industry terminology.
(V
U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th Floor
Chicago, IL 60604-3590
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Technical Resource Document: Uranium
TABLE OF CONTENTS
Page
DISCLAIMER AND ACKNOWLEDGEMENTS i
1.0 MINING INDUSTRY PROFILE: URANIUM 1
1.1 INTRODUCTION 1
1.2 ECONOMIC CHARACTERIZATION OF THE URANIUM INDUSTRY 3
1.3 ORE CHARACTERIZATION 8
1.3.1 Chemical Characterization ' 8
1.3.2 Types of Uranium Deposits 8
1.3.2.1 Stratabound 8
1.3.2.2 Solution Breccia Pipes 11
1.3.2.3 Vein Deposits 12
1.3.2.4 Phosphatic 12
1.4 URANIUM MINING PRACTICES 13
1.4.1 Extraction 13
1.4.1.1 Open Pit Mining 13
1.4.1.2 Underground Mining 15
1.4.2 Beneficiation 15
1.4.2.1 Conventional Milling 18
1.4.2.2 Solution Mining 23
1.5 EXTRACTION AND BENEFICIATION WASTES AND MATERIALS
ASSOCIATED WITH URANIUM MINING OPERATIONS 31
1.5.1 Extraction and Beneficiation Wastes and Materials 31
1.5.1.1 Waste Rock or Overburden 31
1.5.1.2 Mine Water 32
1.5.1.3 Tailings 32
1.5.1.4 Bleed Solution 33
1.5.1.5 Evaporation Pond Sludges 34
1.5.1.6 Drilling Wastes 34
1.5.1.7 Waste Ion Exchange Resins 34
1.5.1.8 Reverse Osmosis Brines 35
1.5.1.9 Acid/Alkaline Leaching, Solvent Extraction, Stripping and
Precipitation Circuit Wastes and Materials 35
1.5.2 Waste and Materials Management 35
1.5.2.1 Overburden, Waste Rock, and Ore 35
1.5.2.2 Mine Pits and Underground Workings 36
1.5.2.3 Tailings Impoundments . . . 36
1.5.2.4 Evaporation Ponds 37
1.5.2.5 Settling Ponds 37
1.5.2.6 Land Application Areas 37
1.5.2.7 Deep Disposal Wells 37
1.6 ENVIRONMENTAL EFFECTS 38
1.6.1 Introduction 33
1.6.2 Surface Water 39
1.6.2.1 Mine Dewatering 39
1.6.3 Ground Water 39
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Technical Resource Document: Uranium
1.6.4 Air 42
1.6.4.1 Radon 42
1.6.4.2 Fugitive Dust 42
1.6.4.3 Soils 43
1.7 CURRENT REGULATORY FRAMEWORK ' 44
1.7.1 Introduction 44
1.7.2 Federal Regulatory Program 44
1.7.2.1 The Uranium Millings Tailings Remediation Control Act 45
1.7.2.2 Nuclear Regulatory Commission 52
1.7.2.3 Department of Energy 56
1.7.3 Clean Air Act 57
1.7.4 Clean Water Act 59
1.7.5 Safe Drinking Water Act 61
1.7.5.1 Class I Nonhazardous Wells 62
1.7.5.2 Class HI Wells 64
1.7.5.3 Class V Wells 65
1.7.6 Selected State Regulatory Requirements 65
1.7.6.1 Texas 66
1.7.6.2 Wyoming 68
1.8 REFERENCES 70
APPENDICES
APPENDIX A NPL SUMMARIES RELATED TO URANIUM
EXTRACTION AND BENEFICIATION
APPENDIX B ACRONYM LIST
LIST OF TABLES
Page
Table 1-1. Effluent Limitation Guidelines for Discharges from Mines and Mills in the
"Uranium, Radium, and Vanadium Ores Subcategory" 61
LIST OF FIGURES
Page
Figure 1-1. Domestic Raw Ore Production-1950 through 1991 4
Figure 1-2. Location of Active and Inactive Milling Operations in the U.S. as of 1991 6
Figure 1-3. Location of the Four Types of Uranium Deposits Found in the LJ.S 9
Figure 1-4. Raw Ore Production from Open Pit and Underground Uranium Mines-1950 to 1991 14
Figure 1-5. Schematic of a Conventional Mill 17
Figure 1-6. Comparison of Acid and Alkaline Leaching Circuits 19
Figure 1-7. Well-Field Patterns 25
in
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Mining Industry Profile: Uranium
1.0 MINING INDUSTRY PROFILE: URANIUM
1.1 INTRODUCTION
This Industry Profile presents the results of U.S. Environmental Protection Agency (EPA) research
into the domestic uranium mining industry and is one of a series of profiles of major mining industry
sectors. Additional profiles describe other industry sectors, including gold, lead/zinc, copper, iron,
and several industrial minerals. EPA prepared these profiles to enhance and update its understanding
of the mining industry and to support mining program development by states. EPA believes the
profiles represent current environmental management practices as described in the literature.
Each profile addresses extraction and beneficiation of ores. The scope of the Resource Conservation
and Recovery Act (RCRA) as it applies to mining waste was amended in 1980 when Congress passed
the Bevill Amendment, Section 3001(b)(3)(A). The Bevill Amendment-states that "solid waste from
the extraction, beneficiation, and processing of ores and minerals" is excluded from the definition of
hazardous waste under Subtitle C of RCRA (40 CFR 261.4(b)(7)). The exemption was conditional
upon EPA's completion of studies required by RCRA Section 8002(f) and (p) on the environmental
and health consequences of the disposal and use of these wastes. EPA segregated extraction and
beneficiation wastes from processing wastes. EPA submitted the initial results of these studies in the
1985 Report to Congress: Wastes from the Extraction and Beneficiation of Metallic Ores, Phosphate
Rock, Asbestos, Overburden From Uranium Mining, and Oil Shale (U.S. EPA 1985). In July 1986,
EPA made a regulatory determination that regulation of extraction and beneficiation wastes under
Subtitle C was not warranted (51 FR 24496; July 3, 1986). EPA concluded that Subtitle C controls
were not appropriate and found that a number of existing Federal and State programs already
addressed many of the risks posed by extraction and beneficiation wastes. Instead of regulating
extraction and beneficiation wastes as hazardous wastes under Subtitle C, EPA indicated that these
wastes should be controlled under Subtitle D of RCRA.
EPA reported their initial findings on mineral processing wastes from studies required by the Bevill
Amendment in the 1990 Report to Congress: Special Wastes From Mineral Processing (U.S. EPA
1990). This report covered 20 specific mineral processing wastes; none involved uranium processing
wastes. In June 1991, EPA issued a regulatory determination (56 FR 27300) stating that regulation of
these 20 mineral processing wastes as hazardous wastes under RCRA Subtitle C is inappropriate or
infeasible. These 20 wastes are subject to applicable state requirements. Any mineral processing
wastes not specifically included in this list of 20 wastes no longer qualifies for the exclusion (54 FR
36592).
In addition to preparing profiles, EPA has undertaken a variety of activities to support state mine
waste programs. These activities include visits to a number of mine sites; compilation of data from
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Mining Industry Profile: Uranium
State regulatory agencies on waste characteristics, releases, and environmental effects; preparing
summaries of mining-related sites on the Superfund National Priorities List (NPL); and an
examination of specific waste management practices and technologies. EPA has also conducted
studies of State mining-related regulatory programs and their implementation.
The purpose of this report is to provide additional information on the domestic uranium mining
industry. It should be noted that the uranium industry has been depressed since the early 1980s and
that the extent of current operations is limited. The report describes current uranium extraction and
beneficiation operations with specific reference to the wastes associated with these operations. It also
refers to activities and impacts documented when the uranium mining industry was more active. The
report is based on reviews of literature and a limited number of State documents. This report
complements, but was developed independently of, other EPA activities, including those described
above. Uranium processing wastes are not addressed in this profile.
This report briefly characterizes the geology of uranium ores and the economics of the industry.
Following this discussion is a review of uranium extraction and beneficiation methods; this section
provides the context for descriptions of wastes and materials managed by the: industry, as well as a
discussion of the potential environmental effects that may result from uranium extraction and
beneficiation. The report concludes with a description of regulatory programs that apply to the
uranium mining industry as implemented by EPA, Federal land management agencies, and selected
states.
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Mining Industry Profile: Uranium
1.2 ECONOMIC CHARACTERIZATION OF THE URANIUM INDUSTRY
The primary demand for uranium is by commercial power generating facilities for use in fuel rods.
Prior to 1942, its primary uses were as a coloring agent in glass manufacturing and in the production
of certain copper, nickel and steel alloys. After the start of World War II, the U.S. began stockpiling
uranium principally for the development of atomic weapons (ElA/DOE, 1991).
In 1946, the Atomic Energy Act (AEA) established the Atomic Energy Commission (AEC) as the
sole purchasing agent for domestically produced uranium. The AEA also set fixed prices for uranium
ore and provided incentives including access roads, haulage allowances, and buying stations in an
effort to bolster development within the domestic uranium mining industry. The AEC acted as the
sole purchasing agent for uranium from 1948 through 1970. Since the end of the Federal buying
program in 1970, private entities have handled sales of uranium between producers and consumers.
The industry slowed in the late 1960s as a result of the a slowdown of the Federal procurement
program which terminated in 1970. Uranium production in the early 1970s remained steady as
commercial markets began to emerge. The industry was revitalized shortly thereafter by the prospect
of supplying fuel to the developing commercial nuclear power industry. Production and prices peaked
in the early 1980s, the same time period when planning and construction of new commercial nuclear
power plants came to a halt (EIA/DOE, 1992). Domestic raw ore production figures since 1950 are
presented in Figure 1.
In the uranium market, references to ore, intermediate, and some final products, are in terms of
percent of uranium oxide or uranium oxide equivalent. Uranium oxide is a generic term for a
number of common chemical forms of uranium, the most common being U3O8. Yellowcake is
another generic term, used to describe the yellow powder generated as the end product of uranium
beneficiation. The purity of yellowcake typically ranges from 60 to 75 percent U3O8 (Merritt, 1971).
A discussion of the different chemical forms of yellowcake is provided in the Extraction and
Beneficiation section of this document.
Uranium is sold to commercial utilities in the U.S. by both domestic and foreign suppliers.
Government stockpiles supply at least a portion of the uranium required by the defense industry.
Suppliers derive their sources from operational mines, natural grade uranium stockpiles (as opposed to
the processed, enriched form used as the component of fuel rods) and foreign sources. Domestic
suppliers delivered 11,125 metric tons of U3Og equivalent to domestic utilities in 1991; commercial
mills in the U.S. provided 3,600 metric tons while suppliers imported almost 2,600 metric tons.
Most of the remaining 4,900 metric tons of U3O8 equivalent supplied to domestic utilities came from
commercial stockpiles. Domestic utilities directly imported an additional 6,400 metric tons of U3O8
equivalent in 1991 (EIA/DOE, 1992).
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Mining Industry Profile: Uranium
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Mining Industry Profile: Uranium
Commercial inventories of U3Og equivalent held in the United States at the end of 1991 stood at over
55,500 metric tons. The Federal government held approximately 21,250 metric tons while the
remainder was held by utilities and domestic suppliers (DOE/EIA, 1992).
Uranium mines within the United States produced 522 metric tons (1.4 million pounds) of U3O8
equivalent in 1992. Production figures from 1992 indicate a drop of over 70 percent from 1991
levels and the lowest level of production since 1951 (see Figure 1). Uranium prices as well as
production are down. In 1992, the average price per pound of uranium oxide equivalent was $8.70,
down from an average of $13.66 in 1991 (DOE/EIA, 1993).
In 1981, the United States produced nearly 14,800 metric tons of U3O8 equivalent at an average price
of over $34 per pound. At the time, the uranium industry reported an employment figure of 13,676
person-years. U3O8 equivalent production in 1991 was approximately 3,600 metric tons sold at an
average price of $13.66 per pound. The 1992 employment figure of 682 person-years reflects the
current trend in production and prices. The EIA reports that in 1992, 51 person-years were expended
in exploration, 219 in mining activities, 129 in milling operations and 283 in processing facilities.
(DOE/EIA, 1992, 1993).
Uranium has primarily been mined in the western United States; Arizona, Colorado, New Mexico,
South Dakota, Texas, Utah, Washington and Wyoming. A total of 17 uranium mines were
operational in 1992; five conventional mines (both underground and open pits), four in situ, and eight
reported as "other" (heap leach, mine water, mill tailings, or low-grade stockpiles). Uranium was
also produced to a limited extent as a byproduct of phosphoric acid production at four sites
(DOE/EIA, 1993). Figure 2 illustrates the location of operational (operational in this case includes
active and inactive mines and mills but not decommissioned mills nor closed (reclaimed) mines) mines
and mills in the U.S. in 1991. (DOE/EIA, 1992)
Total milling capacity for active and inactive conventional mills in 1991 was 14,550 tons per day
(tpd) of ore (the type of tons was not defined). As of 1991, the two active mills (Hobson, Texas and
Shirley Basin, Wyoming) had the capacity to handle a total of 4,800 tpd yet, the total daily feed
averaged 1,920 tpd. The average grade of ores processed in 1991 was 0.198 percent uranium oxide
(USGS, 1990; DOE/EIA, 1991; DOE/EIA, 1992). These two active mills closed during 1992 and
are currently being dismantled.
The percentage of U3O8 equivalent produced by conventional and other mills by State is difficult to
determine. Texas was the largest producer of U3O8 equivalent in 1991 producing 1,063 metric tons
of yellowcake. Wyoming, the second largest domestic producer, produced 1,017 metric tons.
Production of U3O8 equivalent from Arizona, Florida, Louisiana, Nebraska, New Mexico, South
Dakota, and Washington combined totalled nearly 2,850 metric tons in 1991 (DOE/EIA, 1992).
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Mining Industry Profile: Uranium
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(Source: DOE, 1991)
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Mining Industry Profile: Uranium
As part of the annual viability assessment of the domestic uranium mining and milling industry
required by 10 CFR 761, the Secretary of Energy has declared the uranium mining and milling
industry nonviable annually from 1984 through 1991 (DOE/EIA, 1992a). (A definition of viability
was not provided in the report nor 10 CFR 761). A 1992 summary .of various mineral markets
published in the Engineering and Mining Journal (E&MJ) noted that the industry remained depressed
with large inventories and low prices. The report also indicated that the Cigar Lake project in
Canada, with ore reserves capable of supplying most of the uranium needs in the Western
Hemisphere, was scheduled to begin production in the near future (Grisafe, 1992). (The ore grade at
Cigar Lake is approximately eight percent uranium oxide.)
Projections of spot-market demand versus production (under 1992 conditions) indicate the
continuation of a depressed market with demand and production near current levels through the year
2000 (DOE/EIA, 1993).
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Mining Industry Profile: Uranium
1.3 ORE CHARACTERIZATION
In order to understand the operations used to mine and concentrate uranium, it is necessary to discuss
the chemical and physical make-up of uranium ores. Understanding the characteristics of uranium ore
and their host rocks also provides insight into the type of waste products that may be produced as a
result of specific mining or beneficiation techniques. This section presents a brief description of the
geochemistry of uranium minerals and the genesis and physical characteristics of different types of
uranium ore bodies found in the United States.
1.3.1 Chemical Characterization
The element uranium is generally found in naturally occurring minerals in one of two ionic states:
U6+ (the uranyl "oxidized" ion) and U4+ (the uranous "reduced" ion). Minerals containing the uranyl
ion tend to be brightly colored (red, yellow, orange and green) and occur in oxidized portions of
uranium ore deposits. Common uranyl minerals include tyuyamunite (Ca^O^VzOg-SHjO), autunite
(Ca(UO2)2(PO4)2-8-12H2O), torbernite (Cu(UO2)2(PO4)2-8-12H2O) and uranophane
(H3O)2Ca(UO2)2(SiO4)2 -3H2O) (Smith, 1984; Hutchinson and Blackwell, 1984). Minerals containing
the uranous ion are more subdued in color, typically brown or black, and occur in reducing
environments. Common uranous minerals include uraninite (UOj), pitchblende (a crystalline variant
of uraninite) and coffmite (USiO4) (Smith, 1984; Hutchinson and Blackwell, 1984). Uranium occurs
in the minerals as one of three isotopes: U-234, U-235 and the most abundant of the isotopes, U-238
(Tatsch, 1976).
1.3.2 Types of Uranium Deposits
Economically recoverable uranium deposits in the United States generally fit into one of four types of
deposits: stratabound, solution breccia pipes, vein, and phosphatic. Figure 3 depicts the general
geographic location of these four types of uranium deposits within the United States. Forty percent of
the world's uranium reserves occur in the stratabound uranium deposits in the western United States.
These reserves account for more than ninety percent of the U.S. production of uranium and vanadium
(an element that is often present in uranium minerals as well as in accessory minerals) (Guilbert and
Park, 1985).
1.3.2.1 Stratabound
Stratabound is a term used to describe ore deposits that are contained within a single layer of
sedimentary rock. In the United States, stratabound uranium ores are found in three major geographic
areas: the Wyoming Basin, south Texas, and the Colorado Plateau. Grades of ore mined from these
deposits range from 0.15 to 0.30 percent U3O8.
The ore is found in bodies ranging in size from two tons to more than 10 million tons. Several of
these bodies may make up one uranium deposit (Tatsch, 1976).
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Mining Industry Profile: Uranium
Stratabound
Solution Breccia Pipe
Vein
Phosphate
Figure 1-3. Location of the Four Types of Uranium Deposits Found in the U.S.
(Source: DOE, 1991)
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Mining Industry Profile: Uranium
The current theory on the genesis of stratabound uranium orebodies proposes that they formed
through the transport of uranium (and associated elements) by oxidizing groundwater. Groundwater
flowed through uranium-containing rocks or sediments, leaching uranium from the rock through the
oxidation of U4+ to U6+. The U6+ ion is soluble in groundwater as one of many different uranyl
complex ions. These uranium ions remained in solution until they encountered and moved through a
reducing environment. There the uranyl ions were reduced and a uranous mineral, such as uraninite,
was precipitated.
The uranium deposits of the Wyoming Basin and south Texas are known as "roll-front" deposits, a
uranium ore-body deposited at the interface of oxidizing and reducing groundwaters. These deposits
are found in permeable sandstone beds that are generally interbedded with silty claystones or shales.
Tongues of oxidizing groundwater containing uranium (vanadium, molybdenum, selenium, and sulfur
may also be present) in solution flowed through the sandstone beds until reducing groundwater was
reached. Precipitation of the uraninite and accessory minerals occurred at the interface of the
oxidized fluids and the reducing environment. A zonation of mineralization is typically noted in these
deposits; pyrite and calcite are found at the leading edge of the interface, pyrite and uraninite in the
ore-zone and siderite (FeCO3), goethite (FeOOH) and hematite (Fe^) on the trailing edge. The
deposits display a crescent shape in plan view, resulting from the configuration of the interface
between the tongues of oxidizing groundwater and reducing groundwater. As the interface of the
oxidizing and reducing environments migrated, the uranous minerals were deposited over a laterally
extended area. The roll-front ore bodies may only be a few meters in height, but may extend over a
hundred meters in length. These deposits are particularly well suited for in situ solution mining
techniques (see Beneficiation section) due to the high permeability of the host sandstones and their
generally shallow depths (Guilbert and Park, 1985; Texas Department of Water Resources, 1984).
The Salt Wash uranium-vanadium deposits of the Colorado Plateau (includes the Uravan Mineral Belt
in Colorado and Utah) were formed when uranium- and vanadium-enriched groundwater flowed
through zones of high permeability containing solids (organic matter), gases (hydrogen sulfide), or
liquids capable of reducing the uranyl ion. The uranium and vanadium minerals were deposited in the
areas where these substances created reducing environments. The deposits are generally tabular
shaped and are found in sandstones, limestones, siltstones and conglomerates scattered throughout
western Colorado, eastern Utah, northeastern Arizona and northwestern New Mexico. Grades of
these deposits range from 0.16 percent to 0.25 percent U3O8. Significant vanadium is also associated
with these deposits, which grades about one percent V2O5. Other metals associated with these
deposits are copper, silver, selenium, molybdenum, chromium, lead, zinc, arsenic, cobalt and nickel.
Although the primary ore minerals associated with these deposits are the reduced minerals pitchblende
and coffmite, the brightly colored weathering products of these two minerals are also present, the
oxidized uranium and vanadium minerals tyuyamunite, carnotite, and montroseite (Guilbert and Park,
1985).
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Mining Industry Profile: Uranium
The humate uranium deposits of the Colorado Plateau (located in northwestern New Mexico and
known as the Grants Mineral Belt) have provided over 50 percent of the total U.S. uranium
production. These deposits occur in sandstones, arkoses and siltstones of the Morrison Formation.
The uranium is found associated with tabular layers of organic matter (humates) averaging 0.5 to two
meters thick and up to hundreds of meters across. The uranium ore contains the minerals uraninite
and coffmite and an organo-uraniferous mineraloid. These compounds coat sand grains, and fill pore
spaces and fractures. Locally, some younger oxidizing "roll fronts" have advanced through the
uraniferous humate deposits and redistributed the uranium into the characteristic roll-front deposit
(Guilbert and Parker, 1985).
1.3.2.2 Solution Breccia Pipes
Solution breccia pipe uranium deposits occur in the Arizona Strip, an area of northern Arizona known
for high grade uranium deposits. Between 1980 and 1992, seven mines in the Arizona Strip produced
in excess of 19 million pounds of uranium ore averaging 0.64 percent U-238. (Pillmore, 1992). No
production figures were available for uranium ores mined prior to 1980.
These solution breccia pipes (not to be confused with breccia pipes of volcanic origin) were created
by the flow of groundwater through limestones. The neutral to acidic groundwater began to dissolve
the limestone along areas of weakness in the rock. As the dissolution progressed, large cavities
formed in the limestone units. The overlying units, no longer supported by the underlying limestone,
progressively collapsed into the cavities. This progressive collapse of the overlying units resulted in
cylindrical columns of broken rock (commonly referred to as solution breccia pipes). Many of these
structures extend a vertical distance of more than 2,000 feet and may reach 250 feet in width
(Verbeek, Grout and Gosen, 1988; Pillmore, 1992).
The solution breccia pipes became preferential pathways for fluids as a result of their increased
permeability. Sometime after pipe formation, hydrothermal fluids circulated in the pipes and in
fractures surrounding the pipes, depositing uranous minerals in the presence of reducing solids
(ferrous iron, sulfides or organic matter) or liquids. The source of these hydrothermal solutions and
the uranium contained in them is currently open to debate.
Uraninite or pitchblende coats quartz grains and fills small cavities (vugs) in many of the pipes. A
variety of copper, iron, zinc and lead sulfides are also found in what appears to be deposition
contemporaneous with the uraninite. Following the hydrothermal phase, many of the ore minerals
deposited in the pipes were chemically altered as the geological environment changed. Oxidizing, low
temperature groundwater migrated thorough the pipes and oxidized the primary uranium ores to
tyuyamunite, uranophane, torbernite and other uranyl uranium minerals. Copper and zinc sulfides
were altered to carbonate, sulfate and hydrous silicate compounds. In some pipes, this alteration is
nearly complete, eliminating all traces of the primary mineral assemblages. Many of these deposits
11
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Mining Industry Profile: Uranium
have been exploited through underground mining methods (Verbeek, Grout, Van Gosen, 1988 and
Rich, Holland and Peterson, 1977).
1.3.2.3 Vein Deposits
Uranium vein deposits are formed by the migration of hydrothermal solutions through faults and
fractures at moderate temperatures (100 to 300°C) and pressures. As geochemical changes occur in
the solutions, pitchblende and other uranium minerals are precipitated in the veins. In addition to the
uranium minerals, the vein may also contain many different types of minerals. These accessory
minerals may contain any number of metals, including copper, lead, iron and zinc.
Vein deposits of uranium ore may be found in any type of host rock: sedimentary, metamorphic or
igneous. Most uranium vein deposits in the U.S. have been relatively unimportant in U.S. production
(Rick, Holland and Petersen, 1977). Exceptions to this are the Schwartzwalder mine in Colorado, the
Marysvale District in Utah and the Midnite mine in Washington. A current accounting of the total
U.S. uranium production originating from vein deposits was not available.
1.3.2.4 Phosphatic
Uranium was extracted to a limited extent, from the phosphate ores of central Florida until recently.
In these ores, uranium is a trace constituent of apatite (Ca5(PO4)), the primary mineral in phosphate
deposits. The uranous ion (U4+) substitutes for calcium in the crystalline structure of apatite and a
small amount of U6+ may be adsorbed onto the mineral surface. (USGS, 1990)
The central Florida phosphate deposits contain uranium concentrations ranging from 90 ppm to 150
ppm in phosphate pellets, the main form of phosphate ore. The uranium was deposited at the same
time as the apatite and not as a secondary replacement of the calcium. Secondary enrichment of
uranium has occurred in some areas of the phosphate district as a result of leaching by acidic
groundwater. As acidic water percolates through the phosphate rock, uranium and apatite are
dissolved and transported to a geochemical environment favorable for precipitation. This process
secondarily concentrates uranium (up to 1,000 ppm) and apatite (USGS, 1990). Uranium was
recovered from the apatite during the manufacture of phosphoric acid. In 1988, two phosphoric acid
manufacturing plants recovered about two million pounds of U3O8 (21 percent of U.S. production for
1988) from the phosphate rock mined in Florida (USGS, 1990). These operations are now closed.
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Mining Industry Profile: Uranium
1.4 URANIUM MINING PRACTICES
The major operational steps in producing commercial uranium products fall into three broad
categories: extraction, beneficiation and processing. Extraction involves the removal of ore from a
deposit and includes all steps prior to beneficiation. Beneficiation includes the crushing, grinding,
leaching of the ore; it also includes concentration and subsequent precipitation of the uraniferous
compounds. During the last stage of beneficiation the precipitated yellowcake is washed, dried and
packaged for shipment. Typically, yellowcake is shipped to a Federal facility for processing. In the
processing step, uranium fluoride (UF6) is produced from yellowcake. The uranium fluoride is then
enriched, an operation that concentrates the U-235 from a concentration of 0.7 percent to
approximately two to three percent. The enriched uranium fluoride is further refined to ultimately
produce the fuel rods used in nuclear reactors. The terms extraction and beneficiation, for the
purposes of this report, are used in the broadest sense and discussions herein should not be construed
for regulatory purposes for any specific waste. Extraction and beneficiation methods are discussed
further in this section; uranium processing is beyond the scope of the report. A discussion of the
wastes generated during each phase of mining and beneficiation is presented in the next chapter.
1.4.1 Extraction
Uranium is typically mined using one of three techniques: surface (open pit), underground, or
solution mining. (Solution mining is discussed below in the Beneficiation section). The method of
extraction is dependent on the grade, size, location, and geology of the deposit and is based on
maximizing ore recovery within economic constraints. A low-grade cutoff point is established on a
site-specific basis and depends on recovery costs at the site, the market price of the ore, and feed
requirements at the mill. A survey conducted in 1986 indicated that low-grade cutoff values ranged
from 0.01 to 0.3 percent U3O8 (USEPA, 1986).
Unlike operations in many other mineral sectors, uranium ore production levels from open pit and
underground mines were approximately equal for the period of 1978 through 1985 (see Figure 4).
Production figures since 1985 have been withheld as proprietary information, so, more recent
comparisons between the two methods were not possible (EIA/DOE, 1991). It is likely that as the
price of uranium declines, more costly methods of mining, such as underground, have become less
economically feasible.
1.4.1.1 Open Pit Mining
Open pit mining techniques are employed to exploit ore deposits relatively close to the surface of the
earth. Topsoil is typically removed separately and stockpiled. Overburden, the material overlying
the deposit is removed using scrapers or with trucks and loaders or mechanical shovels.
13
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Mining Industry Profile: Uranium
20000 i-
15000
to
c
o
p tl
5 -c 10000
S 1
IS t
cc
§
o
5000
111)
u)taiaiair>wiS)U)U>inc0CD(DO O> A 0> O> Ok O) 01 O> O) O* O) O* O* Ql Oi O) O) O> O> Ol O) OJ O) O) O* O)
Open pit 1000 metric tons
Year
underground ore 1000 metric ton
Total raw ore 1000 metric tons
Figure 1-4. Raw Ore Production from Open Pit and Underground Uranium Mines-1950 to 1991
(Source: DOE/EIA, 1992)
14
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Mining Industry Profile: Uranium
Depending on the extent of consolidation, the overburden may be ripped with bulldozers or blasted
prior to removal. Overburden may be stockpiled outside the pit or placed in mined out portions of
the pit once pit development has progressed to an acceptable point. Mining economics typically
require that overburden haulage be minimized. Once the ore body is exposed, it is ripped, loaded
into trucks, and trucked to an onsite stockpile. The ore can then be moved from the stockpile to the
mill site as required.
The depth to which an ore body is mined depends on the ore grade, nature of the overburden, and the
stripping ratio. Stripping ratios describe the amount of overburden that must be removed to extract
one unit of ore. One report indicates that stripping ratios for open pit uranium mines range from
10:1 to 80:1 with an average of around 30:1 (USEPA, 1983b Vol 2). Stripping ratios at open pit
mines currently in operation were not available. The primary advantage of surface mining is the
ability to move large amounts of material at a relatively low cost, in comparison with underground
operations.
1.4.1.2 Underground Mining
A variety of techniques are employed in underground operations depending on the distribution and
orientation of the ore deposit. In general, underground mining involves sinking a shaft (or driving an
adit) near the ore body to be mined and extending levels from the main shaft at various depths to the
ore. Shafts, adits, drifts and cross-cuts, are developed to access and remove the ore body. Levels
and adits often slope slightly upward away from the main shaft to encourage positive drainage of any
water seeping into the mine. Ore and development rock, the non-ore bearing material generated
during mining, may be removed either through shaft conveyances or chutes, and hoisted in skips
(elevators) to the surface or used to backfill mined out areas. Ore is placed in stockpiles while
development rock brought to the surface is placed in waste rock. As underground mining techniques
are able to leave much of the non-ore bearing material in place, the ratio of waste (development) rock
to ore is much lower than stripping ratios in open pit mines. Ratios of waste rock to ore range from
1:1.5 to 1:16 (USEPA, 1983b Vol 2). In shallow underground mines, ore and waste rock may be
brought to the surfaced by train or conveyor belt. Often, mining progresses from the edge of the ore
deposit or property line toward the main shaft (USDOI, 1980).
As with surface mining operations, ores and sub-grade ores may be stockpiled on the surface. These
materials may be beneficiated as market conditions allow or left with mine development rock in waste
rock piles.
1.4.2 Beneficiation
Beneficiation of ores and minerals is referenced in 40 CFR 261.4(b)(7) as being the following:
crushing; grinding; washing; dissolution; crystallization; filtration; sorting; sizing; drying; sintering;
pelletizing; briquetting, calcining to remove water and/or carbon dioxide; roasting; autoclaving,
15
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Mining Industry Profile: Uranium
and/or chlorination in preparation for leaching (except where the roasting (eind/or autoclaving and/or
chlorination)/leaching sequence produces a final or intermediate product that does not undergo further
beneficiation or processing); gravity concentration; magnetic separation; electrostatic separation;
flotation; ion exchange; solvent extraction; electrowinning; precipitation; amalgamation; and heap,
dump, tank, and in situ leaching. Beneficiation of conventionally mined ores in the uranium industry
involves crushing and grinding the extracted ores followed by a leaching circuit. In situ operations
bypass the extraction step and perform the leaching step using a leach solution to dissolve desirable
metals from deposits in-place. The uranium, in this case, is brought to the surface in solution.
Uranium in either case is removed from pregnant leach liquor and concentrated using solvent
extraction or ion exchange techniques and precipitated to form yellowcake. Prior to 1980,
approximately 90 percent of yellowcake production came from conventional mills; as of 1991,
yellowcake production from conventional mills and in situ operations is close to equal (USDOI, 1980;
DOE/EIA, 1992).
Uranium mills have typically been associated with specific mines or functioned as custom mills,
serving a number of mines. The two mills that operated in 1991 closed in 1992 and are in the
process of being decommissioned (Stephenson, 1993). The specific circuits employed by those mills
for beneficiation, prior to their closure, were not determined. Most available information on milling
operations were written when a dozen or more were operational, therefore the following discussions
may not precisely describe milling activities being conducted at present. Figure 5 illustrates
operations at a typical conventional mill.
The chemical nature of the ore determines the type of leach circuit required and, in turn, the extent of
grinding. Most ores are ground to approximately 28 mesh and acid-leached Ores containing greater
than 12 percent limestone require finer grinding (200 mesh) and are leached with an alkaline solution.
Mills may use one type of circuit or the other although in the past, some mills maintained both acid
and alkaline leach circuits. Solvent extraction or ion exchange circuits can be used to concentrate the
uraniferous compounds from either of the leach circuits (USEPA, 1983a; USDOI, 1980).
The literature indicates that solvent exchange was employed more frequently in conventional milling
operations than ion exchange. Where ion exchange was employed by conventional mills, it appears to
have been conducted as a resin-in-pulp operation rather than using columns. In situ operations
usually employ ion exchange columns for concentration of the uraniferous compounds.
Some limitations of ion exchange columns are the inability to treat solutions with solids and the finite
life of the fixed resins. Ion exchange is effective for in situ operations because of the relative ease
with which resin columns can be transported from satellite areas to a centralized uranium
stripping/precipitation facility.
16
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Mining Industry Profile: Uranium
§
O
Q
CO
17
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Mining Industry Profile: Uranium
1.4.2.1 Conventional Milling
Crushing and Grinding
The initial step in conventional milling involves crushing, grinding, and wet and/or dry classification
of the crude ore to produce uniformly sized particles. A primary crusher, such as a jaw type, is used
to reduce ore into particles less than 150 millimeters (about 6 inches) in diameter. Generally,
crushing continues using a cone crusher and an internal sizing screen until the ore has a diameter less
than 19 mm (3/4 inch). Crushing in jaw and cone crushers is a dry process, with water spray applied
only to control dust. Ore feeds from the cone crusher to the grinding circuit where ball and/or rod
mills, and/or autogenous or semiautogenous grinding, continue to reduce the size of the ore. Water
or leach liquor is added to the system in the grinding circuit to facilitate the movement of the solids,
for dust control, and (if leach liquor is added) to initiate leaching (USDOI, 1980).
Classifiers, thickeners, cyclones or screens are used to size the finely ground ore, returning coarse
materials for additional grinding. The slurry generated in the grinding circuit contains 50 to 65
percent solids. Fugitive dust generated during crushing and grinding is usually controlled by water
sprays or, if collected by air pollution control devices, recirculated into the beneficiation circuit.
Water is typically recirculated through the milling circuit to reduce consumption (USEPA, 1983a).
Leaching
After grinding, the slurry is pumped to a series of tanks for leaching. Leaching is defined as
dissolving metals or minerals out of ore (USDOI, 1968). Two types of leaching have been employed
by uranium mills, acid and alkaline. Acid leaching had been the predominant leaching process
employed by conventional mills although the methods in use at the two mills operating in 1991 were
not determined. Figure 6 illustrates process flow diagrams for acid and alkaline leaching. In the
discussions that follow, an overview of leaching is provided followed by a more detailed description
of both acid and alkaline leaches. Generally, leaching is a simple operation. A solvent (lixiviant) is
brought into contact with the crushed ore slurry (or, in the case of in situ, with the ore in the
ground). The desired constituent (uranyl ions) is then dissolved by the lixiv.;ant. The pregnant
lixiviant is separated from the residual solids (tails); typically the solids are washed with fresh
lixiviant until the desired level of recovery is attained.
The uranyl ions are recovered (stripped) from the pregnant lixiviant. The final steps consist of
precipitation to produce yellowcake, followed by drying and packaging (Pehlke, 1973). The stripped
lixiviant may be replenished and recycled for use within the leaching circuit or as the liquid
component in the crushing/grinding operation. Ultimately, the solids may be washed with water prior
to being pumped to the tailings pond; this wash serves to recover any remaking lixiviant and reduce
the quantity of chemicals being placed in the tailings impoundment. Wash water may be recycled to
the lixiviant or to the crushing and grinding circuits.
18
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Mining Industry Profile: Uranium
7
i '
Grinding
i
, P
Acid
Leaching
t
r^™™" ^"^"""""^^
pco,
Recycle
Sol'n
Grinding
aw* Oeneity Control ••
i4nnt. Ajr 9f
\
I
Carbonate
Leacning
f Reeycte Solution* Waterl
Liquid -Solid*
Separation
SoiVi
1 '
fl
Concentration am
Purification
,
Liquid-Solid ^ _
Separation
• tidue Retidue
• , L ^
Reeafbonation
>'
| Other
Precipitation on«
Purification
Barren fomatmr
Solution °"
ing and
ing
Sol'n
INOOH
i Precipitation ana
Purification
Oevatering and
Solution
Drying
roduct
Product
ACID CIRCUIT
ALKALINE CIRCUIT
Figure 1-6. Comparison of Acid and Alkaline Leaching Circuits
(Source: Merritt, 1971)
19
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Mining .Industry Profile: Uranium
The first step in any uranium leaching operation is oxidation of the uranium constituents. Uranium is
found as uranium dioxide (UO2, U+4 oxidation state) in many deposits (pitchblende and uraninite).
Uranium dioxide is insoluble; to create a soluble form, UO2 is oxidized from the U+4 to the U+6
oxidation state. Iron present within the ore, and oxygen, are used to perform oxidation via the
following reactions:
(1) alkaline UO2 + V4O2 ^ UO3
(2) acid . UO2 + 2Fe+3 ** UO2+2 + 2Fe+2.
(Source: Twidwell et al., 1983)
(Note: iron can be readily reoxidized by the addition of O2, sodium chlorai.e (NaClO3), or manganese
oxide (MnO2) to the lixiviant.)
The second step in leaching is the stabilization of the uraniferous ions in solution. The uraniferous
ions form stable, soluble complexes with sulfate (SO4~2) or carbonate (CO3~2). Sulfuric acid is added
as the source for sulfate ions; sodium bicarbonate, sodium carbonate, or carbon dioxide are added to
alkaline leach circuits to provide a carbonate source. Uraniferous complexes are formed through the
following reactions:
(1) alkaline UO3 + CO32 + 2HCO3 ** UO2(CO3)3'4 + H2O
(2) acid U02+2 + 6S04-2 *± UO2(SO4)6'4.
(Source: Twidwell et al., 1983)
In a typical acid leaching operation, sulfuric acid is added to the crushed ore slurry to maintain the
pH between 0.5 and 2.0. Twenty to 60 kilograms of sulfuric acid per metric ton of ore are normally
required to reach the target pH. NaClO3 or MnO2 is added to maintain the oxidation by iron.
Because iron is normally found in uranium deposits, the ore body itself supplies the iron in the leach
step (Twidwell et al., 1983; USEPA, 1983a).
Alkaline.leaching is not as effective as acid leaching for uranium recovery and is not used except in
cases of high lime-content ores. Typically, ore bodies containing greater thaji 12 percent carbonates
will be alkaline leached. Alkaline leaching is primarily employed in in situ mining operations,
although a few conventional mills maintained alkaline leach circuits (Merritt. 1971). Alkaline
leaching requires the use of a strong oxidant and long retention times to oxidize the uraniferous
minerals (Twidwell et al., 1983). As stated previously, oxygen and a carbonate source are added to
water to make up the lixiviant. The carbonate (CO32) and bicarbonate (HCO30 concentrations are
typically 40-50 g/L and 10-20 g/L respectively (Merritt, 1971). For its leaching process, the
Highland in situ project injects O2(g) and CO2(g) into the lixiviant prior to underground injection.
The dissolution of CO2 in the lixiviant produces both CO3 2 and HCO3 ions (Hunter, 1991).
Leaching may be performed in tanks, heaps or in situ. In situ leaching is practiced on low grade
ores; (after crushing and grinding) high grade ores are typically leached in ta.nks. Heap leaching is
20
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Mining Industry Profile: Uranium
also applicable to low grade ores; however, the available literature indicates that the application of
this technique to uranium ores is limited and consequently it will not be discussed in detail.
Depending on the grade of the ore, grain size (amount of grinding), and the method used, the leach
times vary. Leaching in tanks may take from four to 24 hours while heap leaching may be measured
in days or weeks (Twidwell et al., 1983).
Once the uraniferous compounds have been leached from the ore, the pregnant leach solution is
separated from the solids using classifiers, hydrocyclones and thickeners. Sand-sized particles are
removed first and washed with clean water or raffinate (raffinate is another term used to refer to
barren lixiviant). Continued treatment removes the slimes, which are also washed. Depending on the
settling time allowed by beneficiation operations, flocculants may be added to the process to
encourage settling of suspended solids. After final washing, the solids (sands and slimes) are pumped
as a slurry to a tailings pond for further settling. The pregnant leach solution then enters a solvent
extraction or ion exchange circuit. Wash solution is recycled to reduce consumption of leach
chemicals, solute, and water (USDOI, 1980; USEPA, 1983a).
Solvent Extraction
Solvent extraction is an operation that concentrates specific ions. Generally, solvent extraction uses
the immiscible properties of two solvents (the pregnant leach solution and a solvent) and the solubility
properties of a solute (uraniferous ions) in the two solvents. Solvent extraction is typically employed
by conventional milling operations since solvent extraction can be used in the presence of fine solids
(slimes). The pregnant leach solution is mixed in tanks with the solvent. Selection of a solvent in
which the target solute (uraniferous ions) is preferentially soluble allows the solute to migrate to the
solvent the pregnant leach solution while other dissolved compounds remain in the leach solution.
Normally, the solvents are organic compounds that can combine with either solute cations or solute
anions. As uranyl-carbonates or sulfates are commonly generated in the leaching step, anionic solvent
extraction solutions are typically employed; cationic solvent extraction solutions may be employed
depending on unique characteristics of the ores or leaching solutions.
Some anionic SX solutions include:
• Secondary amines with aliphatic side chains
• High molecular weight tri-alkyl tertiary amines
• Quaternary ammonium compounds.
Some cationic SX solutions include:
• Monododecyl phosphoric acid (DDPA)
• Di-2-ethylhexyl phosphoric acid (EHPA)
• Heptadecyl phosphoric acid (HDPA)
• Dialkyl pyrophosphoric acid (OPPA).
(Source: Twidwell et al., 1983).
21
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Mining Industry Profile: Uranium
Typically, the solvent extraction solution is diluted in a low cost carrier such as kerosene with a
tributyl phosphate modifier or a long chain alcohol (Twidwell et al., 1983). The uraniferous ions
preferentially move from the aqueous pregnant leach solution into the organic solvent as the two are
mixed and agitated (USDOI, 1980). After the uraniferous compounds are thus extracted from the
pregnant leach solution, the barren lixiviant (raffinate) is typically recycled 1:0 the leaching circuit.
After the solute exchange has taken place, the pregnant solvent extraction liquor must be stripped.
The uraniferous solute is typically in an anionic state, and accordingly many solvent extraction
solutions are anionic-based. Amine solvent extraction solutions can be stripped by many different
agents such as nitrates, chlorides, sulfates, carbonates, hydroxides, and acids. Chlorides are used
most frequently due to their cost-effectiveness (Twidwell et al., 1983).
The pregnant stripping liquor is then pumped to the precipitation step while the stripped organic
solvent is recycled to the beginning of the solvent extraction circuit. Solvent exchange can be done as
a batch or continuous process (Twidwell et al., 1983).
Ion Exchange
Like solvent extraction, ion exchange operations make use of organic compounds to perform solute
concentration. Generally, fixed organic resins contained within a column ars used to remove
uraniferous compounds from the pregnant leach solution by exchange. After adsorption, the
uraniferous compounds attached to the resins are released (eluted) by a stripping solution and sent to
precipitation. Ion exchange is used by most if not all in situ operations and was employed by some
conventional mills. It was not determined if the currently operational mills employ ion exchange
circuits within their operations.
Resins are constructed with anionic or cationic functional groups (typically anionic for uranium
compounds) that have an affinity for the target compound and specifically bind the compound to the
resin. Resins are synthetic polymers in which hydrocarbon groups make up a three-dimensional
network that hold stable, reactive functional groups (e.g., strong acid-SO3H; weak acid-COOH;
strong base-NR3Cl; weak base-NH2RCl). Resins containing acid groups are called cation exchangers
while resins containing basic groups are termed anion exchangers (Twidwell et al., 1983). Chloride
ions can exchange with the anionic component of all the functional groups, thus providing an
inexpensive stripping solution (i.e., any chloride salt solution) for any of the resins.
As the pregnant leach solution passes through the ion exchange resins, the uraniferous compounds
bind to the resins. The barren leach solution is recycled back to the leaching circuit. As the resins'
binding ports are filled by the uranyl ions, the uranyl ion concentration at the outlet of the ion
exchange column increases. Once the uranyl ions at the outlet reach a predetermined concentration,
the column is considered to be loaded and ready for elution. Typically, the pregnant leach stream is
then directed to a fresh vessel of resins. A concentrated chloride salt solution is then directed through
22
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Mining Industry Profile: Uranium
the loaded resins, eluting off the uraniferous complexes. The pregnant elute liquor can then be
directed to the precipitation circuit. The pregnant elute solution may be acidified slightly to prevent
the premature precipitation of uraniferous compounds (Twidwell et al., 1983).
Yellowcake Production
Once the uraniferous ions have been concentrated by solvent extraction or ion exchange, they are
precipitated out of solution to produce yellowcake. The precipitate is then washed, filtered, dried and
drummed. The chloride stripping solution is recycled back to the stripping circuit. The type of ion
concentration solution (e.g., acid or alkaline solution) governs the precipitation method employed.
With acid pregnant stripping liquors or pregnant elute liquors, neutralization to a pH of 6.5 to 8 using
ammonia hydroxide, sodium hydroxide or lime results in the precipitation of ammonium or sodium
diuranate (Merritt, 1971). Hydrogen peroxide may also be added to an acid pregnant stripping liquor
or pregnant elute liquor to precipitate uranium peroxide (Yan, 1990). All forms of the uraniferous
precipitate are known as yellowcake.
Alkaline pregnant stripping liquors or pregnant elute liquors typically contain uranyl carbonates.
Prior to precipitation of the uranyl ions, the carbonate ions must be destroyed. An acid (usually
hydrochloric acid) is added to the carbonate concentrate solution to break down the carbonates to
carbon dioxide; the carbon dioxide is vented off. Once the carbonates have been destroyed, the
acidified solution is neutralized with an alkali or treated with hydrogen peroxide to precipitate the
uraniferous compounds. Precipitation operations based on neutralization of acid solutions are favored
because of the higher purity of the yellowcake product; sodium, carbonate, and, in some cases,
vanadium, are impurities that may be present in yellowcake produced from an alkaline neutralization
(Merritt, 1971).
The yellowcake is separated from the precipitation solution by filtration. Thickeners may be used in
conjunction with filtration units. The filtered yellowcake can then be dried and packaged for
shipping (USBOM, 1978). The supernatant generated from precipitation and dewatering circuits can
be recycled to the respective solvent extraction or ion exchange stripping solution.
1.4.2.2 Solution Mining
Solution mining is a general term used in the uranium industry to describe operations in which a leach
solution, referred to as the lixiviant, is employed to extract uranium from subsurface ore deposits.
The chemical reactions involved in in situ leaching are the same as those described in the Leaching
section above. A number of solution mining techniques have been explored since the 1960s,
including in situ leaching, slope leaching, borehole mining, and minewater treatment.
Other than in situ, the application of solution raining techniques has been limited. Slope leaching
involves the injection of lixiviant into mined-out areas or those sections of underground mines that
23
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Mining Industry Profile: Uranium
had been backfilled with low grade ore. The lixiviant can be recovered from a sump or well drilled
to the bottom of the mine workings. Like other solution mining techniques, this method allows the
recovery of uranium from ores not economically minable using conventional methods. Stope leaching
was used to a limited extent in Wyoming (Smith Ranch) and in New Mexico (Quivira) (Michel, 1977;
Ingle, 1993; Parker, 1990).
Mine water treatment involves recovery of uranium from mine effluent and was used at one point at
the inactive Schwarzwalder Mine in Colorado. Available information indicates that uranium was
recovered using ion exchange techniques (see above) although the recovered uranium was sent to the
Cotter Mill for storage (Cray, 1990).
Borehole mining (or water-jet mining) is a technique the U.S. Bureau of Mines demonstrated on
uranium deposits in the late 1970s. Borehole mining combines conventional and in situ mining
techniques and involves removal of uranium-containing sandstone from underground deposits using a
high-pressure water jet. The jet, inserted down one borehole, is used to fragment the sandstone,
creating a slurry which is moved to the surface via an adjacent recovery well (USDO1, 1980). No
information on the use of borehole techniques in actual production was obtained.
In situ leaching is the most commonly employed solution technique and continues to be employed at
present by at least two mines in Wyoming. Nebraska's Department of Environmental Control
permitted an in situ operation in 1990; it is currently operable (NDEC, 1990). Texas has 17 mines
that are permitted for in situ operations and only two of these are currently being mined. The rest
have ground water restoration activities underway (Kohler, 1993). Deposits amenable to in situ
leaching are usually (if not always) within an aquifer. Water quality within a mineral deposit may
vary depending on the presence of and boundary between oxidizing and reducing groundwaters. Ore
body characteristics, including chemical constituents, grade, and permeability, are key considerations
in the development of production methods (selection of lixiviants, arrangement of well patterns).
Ideally, the deposit should be confined by impermeable strata above and below the deposit to prevent
contamination of adjacent aquifers by excursions (solution leaks from the ore zone). In situ
production operations consist of three phases: removal of minerals from the deposit, concentration of
uraniferous minerals, and generation of yellowcake. In addition to the production operations, water
treatment and, in some cases, deep well injection facilities, are employed.
In in situ mining, barren lixiviant is pumped down injection wells into the ore body; production wells
then bring the pregnant leach solution to the surface for further beneficiation. Numerous well
patterns have been investigated since the early 1960s when in situ mining techniques were first
employed. Five spot well patterns, which consist of four injection wells forming the corners of a
square, and a production well in the center, are common in the industry. Alternating injection and
production wells are used in narrow deposits (see Figure 7). The spacing between injection and
production wells can range from 20 to 200 feet. The number of well patterns in a well field varies.,
24
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Mining Industry Profile: Uranium
i - ! • !
9—~-
>. ->, >
• i • <
Multiplt fivt-fpot potttrn Multiple ttvtn-ipot potttrn
KEY
o Inaction wtll
• Production w«il
Figure 1-7. Well-Field Patterns
(U.S. BOM, 1978)
25
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Mining Industry Profile: Uranium
and a specific range of numbers was not obtained. Mining units are portions of the deposit to be
mined at one operation, often following "pods" of ore deposited along a rol. front.
Mining units may be mined in sequence or simultaneously. Pumping rates at one in situ operation in
Wyoming ranged from two gallons per minute (gpm) to 30 gpm for injection wells and five gpm to
40 gpm for production wells. Approximately one percent of the fluid drawn from the well field is
removed as a bleed to generate a cone of depression within the "production zone." Pumping rates
can be varied at each well individually in order to compensate for differences in permeability of the
deposit and the gradient being generated by the production operation.
The constituents of the lixiviant used at the
Highland Uranium Project in situ operation in
Wyoming are as follows:
Na
Cl
S04
IDS
pH
HCO
30-200 mg/1
50-900 mg/1
100-400 mg/1
500-1850 mg/1
6.2-6.5
200-1200
30-600 mg/1
Source: WDEQ, 1991.
Lixiviant is introduced to the deposit through
injection wells to initiate the operation. The
lixiviant consists of two parts, an oxidizing
agent, which acts to solubilize the target
minerals, and a complexing agent, which binds
to the target minerals, keeping them in solution.
In the developmental stages of in situ mining,
lixiviants were selected based solely on their
ability to dissolve and mobilize the target
minerals. Sulfuric acid, nitric acid, ammonium
carbonate/bicarbonate and sodium carbonate
were among the first lixiviants used. Sulfuric •^^M^HHM^M^MMHH^HHI^HHMH^HM^H
acid lacked effectiveness in carbonaceous deposits and, while nitric acid was more effective on
carbonaceous ores, the nitrogen component made aquifer restoration difficult. Ammonium
carbonate/bicarbonate leach solutions also presented problems in the restoration phase. Sodium-based
lixiviants allowed for relatively easy aquifer restoration; however, in some cases, the sodium fraction
reacted with clays in the deposits, reducing permeability of the aquifer (in the immediate vicinity of
the injection wells) (USBOM, 198Ib). According to permit documents, Wyoming in situ operations
recover uraniferous minerals using oxygen gas as the oxidizer and carbon dioxide, which ultimately
forms complexes with uranium to form uranyl carbonates, as the complexing agent (WDEQ, 1991).
Operational steps in in situ mining are straightforward. The barren lixiviant is charged with carbon
dioxide as the solution leaves the ion exchange facility (discussed in more detail later in this chapter).
Oxygen is injected to the solution in the wellfields, immediately before the lixiviant moves into the
injection wells. As the solution moves through the deposit, uraniferous minerals are oxidized and
move into solution. (A discussion of the oxidation and complexing is provided in the Leaching
section above.) Carbon dioxide in the lixiviant reacts with water, forming carbonic acid, which in
turn complexes with the solubilized uraniferous ions, forming uranyl carbonates. The uranyl
carbonates and gangue minerals solubilized in the operation remain in solution as the pregnant
solution is pumped to the surface through production (recovery) wells.
26
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Mining Industry Profile: Uranium
Pregnant lixiviant is pumped from the production wellheads through sand filters to remove any large
particulates; the lixiviant is then transferred to the ion exchange units. Depending on the facility, the
ion exchange resins may be placed in trailer-mounted tanks or moved via tanker truck from satellite
plants to a central processing facility. Ultimately, the uraniferous compounds are stripped from the
resins and precipitated to form yellowcake. The ion exchange and precipitation steps are discussed
respectively in sections above. The lixiviant is recharged with carbon dioxide and oxygen following
the ion exchange circuit and injected back into the ore body.
Uranium recovery rates at in situ operations are highest within the first year of operation;
economically viable recovery within a wellfield usually lasts one to three years under recent (1990s)
market conditions. The efficiency of recovery is variable; the Highland Uranium Project in Wyoming
reportedly recovers 80 percent of the estimated uranium reserve at the end of the production cycle
(Hunter, 1991).
When uranium recovery drops below a previously determined point, lixiviant injection is terminated
and the restoration phase is established in the wellfield. Aquifer restoration is required under State
regulatory programs (see the Current Regulatory Framework chapter below). Normally, an aquifer
must be restored to its previous water use classification although not all water quality parameters are
necessarily returned to baseline values.
Restoration
Restoration of the aquifer can be conducted using one (or more) of the following techniques:
groundwater sweep, forward recirculation, reverse recirculation, and directional groundwater
sweeping. In some cases, a reducing agent may be injected prior to any restoration to reverse the
oxidizing environment created by the mining process. A reducing agent may also be injected during
later stages of restoration if difficulties arise in stabilizing the aquifer (Lucht, 1990).
A groundwater sweep involves the selective operation of production wells to induce the flow of
uncontaminated groundwater into the mined zone while the withdrawn water continues to be treated
through the ion exchange circuit. Contaminated water withdrawn from the aquifer can be disposed of
in lined evaporation ponds or treated and discharged. Groundwater sweeps are most effective in
aquifers with "leaky" confining layers, since uncontaminated groundwater can be induced to flow into
the mined areas. Typically, two or more pore volumes are required to improve water quality
parameters. The disadvantage to groundwater sweeping is its consumptive use of groundwater
(Osiensky and Williams, 1990).
Forward recirculation involves the withdrawal and reinjection of groundwater through the same
injection and production wells that were used during the mining operation. Groundwater withdrawn
from the mined aquifer is treated using ion exchange or reverse osmosis with the clean water being
reinjected and recirculated through the system. The water being reinjected is treated to the extent that
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it meets or exceeds the water quality required at the endpoint of restoration. The method does not
allow the removal of any lixiviant or mobilized ions that may have escaped from the mined aquifer.
For this reason, forward recirculation is most effective in restoring the portions of the aquifer
associated with the interior of the well field (Osiensky and Williams, 1990).
Reverse circulation techniques can also be employed in which the function of production and recovery
wells is reversed. Again, "clean" water is injected, this time through the recovery wells, while the
injection wells are employed to withdraw groundwater from the aquifer. This method is also more
effective in restoring the aquifer in the interior of the well field than along r.he perimeter (Osiensky
and Williams, 1990).
Directional groundwater sweeping techniques involve the pumping of contaminated groundwater from
specific wells while treated water (at or surpassing baseline quality) is injected into the aquifer beyond
the mined sections of the aquifer. The clean water is then drawn into the contaminated portions of
the aquifer, removing the mobilized ions. Clean water injection can progress across a wellfield as the
contaminants are progressively withdrawn (Osiensky and Williams, 1990).
Uranium can be recovered during the early stages of the restoration process as the water from the
production wells passes through the ion exchange system. Eventually, uranium recovery is abandoned
while restoration continues. A rinse of multiple aquifer pore volumes is typically required to reach a
satisfactory level of restoration. The number of pore volumes required depends on ease with which
the aquifer returns to baseline conditions and the permit requirements establ ished in State permits
(Osiensky and Williams, 1990; BOM, 1979).
Demonstration of successful restoration is accomplished through extended monitoring. The state of
Wyoming, for example, requires that selected wells be monitored for stabiliiy for a period of at least
six months following the return of monitoring parameters to baseline level (WDEQ, 1990).
Monitoring
In situ operations maintain monitor wells and a monitoring plan to detect any migration of the
lixiviant from the production zone. Such movement of the lixiviant or any of its constituents from the
mined portion of the aquifer into adjacent or overlying aquifers is termed an excursion. Excursions
may be either vertical or horizontal. Horizontal excursions typically occur when pumping rates from
production wells do not create a large enough cone of depression to maintain the lixiviant within the
production zone. These excursions are brought under control by adjusting the pumping rates within
the injection and production wells. Vertical excursions occur when lixiviant constituents are detected
in an aquifer (typically) above the production zone. Vertical excursions may develop as a result of a
leaky confining layer, improper construction of injection or production wells, or, more commonly,
from wells previously drilled into the aquifer that were not adequately plugged before mining
operations commenced. Vertical excursions are more difficult to remedy and may require extensive
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testing to identify the source of the 'leak'. Wells may need to be sealed and new wells installed,
depending on the source and severity of the vertical excursion. The number of excursions occurring
at in situ operations has decreased with the growth in understanding of the causes of excursions and
methods to avoid them. This technology developed with expansion of the industry through the 1980s
(NRC, 1986).
As part of the monitoring program, upper control limits (UCLs) are established during baseline data
collection. UCLs consist of groundwater parameters that would be expected to rise in the event of an
excursion (NRC, 1986). Total dissolved solids, chloride, sulfate, bicarbonate and sodium have been
used as UCLs by uranium in situ operations (WDEQ, 1990). Since horizontal and vertical excursions
may occur, monitoring wells are established both above and below the production zone as well as
around it. Monitoring for the purpose of detecting excursions is conducted on a regular basis usually
established in the operating permit.
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1.5 EXTRACTION AND BENEFICIATION WASTES AND MATERIALS ASSOCIATED
WITH URANIUM MINING OPERATIONS
This section describes several of the wastes and materials that are generated and/or managed at
uranium extraction and beneficiation operations and the means by which they are managed. A variety
of wastes and other materials are generated and managed by uranium mining operations.
Some, such as waste rock and tailings, are generally considered to be wastes and are managed as
such, typically in on-site management units. Even these materials, however, may be used for various
purposes (either on- or off-site) in lieu of disposal. Some quantities of waste rock and tailings, for
example, may be used as construction or foundation materials at times during a mine's life. Many
other materials that are generated and/or used at mine sites may only occasionally or periodically be
managed as wastes. These include mine water removed from underground workings or open pits,
which usually is recirculated for on-site use but at times can be discharged to surface waters. Some
materials are not considered wastes at all until a particular time in their life cycles.
The issue of whether a particular material is a waste clearly depends on the specific circumstances
surrounding its generation and management at the time. In addition, some materials that are wastes
within the plain meaning of the word are not "solid wastes" as defined under RCRA and thus are not
subject to regulation under RCRA. These include, for example, mine water or process wastewater
that is discharged pursuant to an NPDES permit. It is emphasized that any questions as to whether a
particular material is a waste at a given time should be directed to the appropriate EPA Regional
office.
Wastes and materials generated by uranium mining operations include waste rock, tailings, spent
extraction/leaching solutions, and refuse. Mining method (conventional versus solution) has a bearing
on the types of wastes and materials produced. Operational mills function independently of specific
mines and generate materials that are, in most cases, unique from those generated at the site of
extraction. Under the Uranium Mill Tailings Remediation Control Act (UMTRCA, see Regulatory
section below), source handling licenses place specific requirements on the disposal of radioactive
wastes; the design and construction of tailings impoundments typically address Nuclear Regulatory
Commission (NRC) requirements for permanent storage of these wastes. Radionuclide-containing
wastes generated by in situ operations are typically shipped to tailings impoundments at mill sites.
The greatest volume of waste generated by conventional mineral extraction (open pit and underground
mines) is waste rock, which is typically disposed of in waste rock piles. Some waste rock is used for
onsite construction (roads, foundations). The generation of acid mine drainage is one of the principal
concerns surrounding waste rock in other mineral sectors; the potential for generation of acid drainage
from uranium waste rock has not specifically been addressed in the references reviewed for this
profile. However, pyrite is typically a constituent of uranium-containing ores, and may present the
potential to great acid mine drainage in sufficient concentrations. Other materials generated by open
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pit and underground mining operations, including low-grade ore and mine water, are typically
managed on-site during the active life of the facility. Low-grade ores that
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1.5.1.2 Mine Water
Mine water is generated when water collects in mine workings, both surface and underground, as a
result of inflow from rain or surface water and of groundwater seepage. Surface water is generally
controlled using engineering techniques to prevent water from flowing into the mine. During the life
of the mine, water is pumped out of the mine as necessary to keep the mine dry and allow access to
the ore body for extraction. This water may be pumped from sumps within the mine pit or
underground workings or may be withdrawn from the vicinity of mining activity through interceptor
wells. Interceptor wells are used to remove groundwater, creating a cone of depression in the water
table surrounding the mine; the result is dewatering of the mine. Mine water may be treated and
discharged (subject to 40 CFR 440 Subpart C), or, if a mill is operating on-site, mine water can be
pumped to the beneficiation circuit or to tailings impoundments.
The quantity and chemical composition of mine water generated at mines vary by site. The chemistry
of mine water is dependent on the geochemistry of the ore body and surrounding area. The two
principal concerns surrounding mine water associated with uranium mining are the potential for acid
mine drainage and the presence of radionuclides.
Information on the potential for generation of acid mine drainage from uranium mine workings and
waste rock was not available. While pyrite (an acid-forming mineral) is present in some uranium ore
deposits, many uranium mines are located in arid climates. Low precipitation rates and the resultant
lack of water may reduce the potential for generation of acid drainage (at least in the short term) from
waste rock in both the Colorado Plateau and the Shirley Basin of Wyoming.
The presence of radionuclides in mine effluent has been documented and, in at least one case,
uranium was recovered using ion exchange on effluent seeping from an inactive underground mine.
The presence of elevated levels of radionuclides in alluvial aquifers in the Grants Mineral Belt, New
Mexico, were attributed to authorized discharges from mines (discussed in the Environmental Effects
section of this report) (Eadie and Kaufmann, 1977).
1.5.1.3 Tailings
Most wastes generated by conventional mills are disposed of in tailings impoundments.
Wastes are primarily disposed of in the form of a slurry composed of tailings, gangue (including
dissolved base metals), spent beneficiation solutions, and process water bearing carbonate complexes
(alkaline leaching) and sulfuric acid (acid leaching), sodium, manganese, and iron. The
characteristics of this waste vary greatly, depending on the ore, the beneficiation procedure, and the
source of the water (fresh or recycled). The liquid component is usually decanted and recirculated to
the crushing/grinding or leaching circuit.
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Tailings typically consist of two fractions, sands and slimes. The sand and slimes may be combined
and deposited directly in the impoundment or may be distributed through a cyclone such that the sand
fraction is directed toward the dam while the slimes are directed to the interior of the pond (Merritt,
1971).
The fate of radionuclides is of special interest in uranium mill tailings. Radium-226 and thorium-230
are the principal constituents of concern and are associated with the slime fraction of the tailings.
Radon-222 (gas) is also a tailings constituent. The concentrations of radionuclides in the tails will
vary depending on the leach method used (thorium is more soluble in acid than alkaline leaches);
typically, tailings will contain between 50 and 86 percent of the original radioactivity of the ores
depending on the proportion of radon lost during the operation (Merritt, 1971). Other tailings
constituents (including metals, sulfates, carbonates, nitrates, and organic solvents) would also be
present in the tailings impoundment depending on the type of ore, beneficiadon methods, and waste
management techniques.
1.5.1.4 Bleed Solution
Bleed solutions are generated in both the extraction and restoration phases of in situ mining. There
are three pathways that lead to the solution bleeds. During the extraction phase, a one percent bleed
is typically maintained to develop the cone of depression within the mined aquifer (i.e., one percent
less barren lixiviant is injected than the amount of pregnant solution withdrawn). The bleed is drawn
from the circuit following the ion exchange columns and prior to the lixiviant being recharged for
reinjection. Aalso, in the early phases of restoration, lixiviant injection is terminated; however, the
solution removed by recovery wells is also sent through ion exchange to recover uranium remaining
solubilized in the deposit. A bleed is maintained through this operation, again following the ion
exchange step. In addition, as recovery of uraniferous components drops and ion exchange becomes
uneconomical, solution (water) withdrawn from the mined aquifer through recovery wells is treated
with reverse osmosis prior to being reinjected to the aquifer (see the discussion of Restoration above).
A bleed is maintained through this point to insure that clean water is drawn into the aquifer being
restored.
In each of the above cases, the bleed is usually pumped from the extraction/restoration circuit to lined
settling ponds where barium chloride is added. Barium chloride reacts with radium to form a barium-
radium-sulfate precipitate which is allowed to settle out of solution. When the radium levels reach
acceptable levels (typically less than 30 mg/1), the water may be pumped to a holding (surge) pond,
discharged to surface water through an NPDES-permitted outfall, land applied, or, may be stored in a
storage pond for injection during the restoration phase.
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1.5.1.5 Evaporation Pond Sludges
In situ bleed solutions and lixiviant leaching solutions constitute the major source of wastes directed to
lined evaporation ponds. These solutions consist of barren lixiviant and usually have elevated levels
of radium; other contaminants (metals, salts) are limited to what may have been solubilized by the
lixiviant or contaminants in solutions used for beneficiation. Barium chloride is added to the
evaporation ponds which, in the presence of radium, forms a barium-radium-sulfate precipitate. This
precipitate forms the majority of the sludges in the settling/evaporation ponds at in situ mining
operations. Alkali chlorides and carbonates are other likely constituents (USEPA, 1983b Vol. 2).
These sludges are collected at the completion of mining (unless required sooner) and disposed of at an
NRC-licensed disposal facility. The Agency does not have information regarding the specific
chemical composition or radioactive level of these precipitants.
Evaporation pond sludges at conventional mills may also contain barium-radium-sulfate precipitates in
addition to chemical wastes from the leaching and stripping circuits. These sludges may contain
metals, sulfates, chlorides, lime, and amines depending on the leaching methods and waste disposal
practices (Merritt, 1971).
1.5.1.6 Drilling Wastes
The number of wells involved in an in situ mining operation indicates that there may be significant
quantities of wastes associated with drilling operations (drilling muds, cuttings, water). Drilling
wastes (muds, cuttings, produced water) are typically directed into unlined pits adjacent to the wells.
Following well completion, the pits and their contents are typically closed in-place. The majority of
the cuttings generated in drilling operations are non-ore bearing and therefore contain little in the way
of radioactive minerals (USEPA, 1983b Vol. 2).
1.5.1.7 Waste Ion Exchange Resins
Ion exchange resins have a limited life span and must occasionally be replaced. Resins consist of two
portions, an organic structural component and (cationic or anionic) functional groups attached to the
organic framework. The chemical composition of functional groups varies from strong acid groups to
strong base groups. In situ operations typically dispose of spent resins with other so-called
"contaminated waste" in labelled containers prior to disposal at an NRC-licensed disposal facility.
Conventional mills would typically dispose of spent ion exchange resins in the tailings impoundment.
The volume of spent ion exchange resins generated on an annual basis was not determined. At
conventional mills, however, the contribution of spent resins to the volume of a tailings
impoundment would be minimal compared to the volumes of tailings.
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1.5.1.8 Reverse Osmosis Brines
The reverse osmosis process is used by in situ operations to treat effluent prior to final discharge and
to treat groundwater during the restoration phase. Reverse osmosis wastes are typically high in salts
(total dissolved solids) and may have concentrations of radionuclides that exceed NPDES discharge
limits. These wastes are typically injected into deep disposal wells permitted under the UIC program
(UIC permit requirements are discussed in the Current Regulatory Framework section of this report)
(USEPA, 1983b Vol. 2). The quantities generated and more detailed characteristic data were not
obtained.
1.5.1.9 Acid/Alkaline Leaching, Solvent Extraction, Stripping and Precipitation Circuit Wastes and
Materials
Under normal operating procedures, solutions are recycled to the greatest extent possible to conserve
water, chemicals, and uranium. Detailed discussions on the longevity and management of
beneficiation solutions were not obtained. All wastes and materials generated during the beneficiation
operation are likely to contain radionuclides in at least trace quantities as well as other metals
dissolved from the ore.
In addition to radionuclides, solvent extraction solutions include phosphoric acids (cationic ion
exchange), amines and ammonium salts (anionic ion exchange), and organic carriers such as kerosene
or alcohol. Stripping solution could contain nitrates, chlorides, sulfates hydroxides or acids. Wastes
from the ion exchange solution are dependant on the type of resins employed, however, chloride
solutions are commonly used for elution. Constituents that could accumulate in the precipitation
circuit are primarily anions - sulfates, chlorides and possibly, carbonates (Merritt, 1971; Twidwell et
al., 1983). Again, information on quantities and characteristics were not obtained.
1.5.2 Waste and Materials Management
Wastes and nonwaste materials generated as a result of extraction and beneficiation of uranium ore
are managed (treated, stored, or disposed) in discrete units. For the purposes of this report, these
units are divided into six groups: (1) mine structures such as pits and underground workings; (2)
overburden, waste rock, and ore; (3) tailings impoundments; (4) settling/evaporation ponds; (5) land
application areas; and (6) deep disposal wells.
1.5.2.1 Overburden, Waste Rock, and Ore
Overburden and waste rock removed from the mine are stored or disposed of in unlined piles on site.
Often constructed without liners, these waste dumps are generally unsaturated in the arid regions
where most uranium mining occurs. Such dumps could possibly generate acid drainage if pyrites or
other sulfide minerals and moisture are present in sufficient concentrations. Concentrations of
radionuclides are likely to be similar to those in adjacent, undisturbed deposits although radon (gas)
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levels may be higher as a result of higher diffusion rates through unconsolidated piles as opposed to
undisturbed bedrock. Topsoil may be segregated from overburden and waste rock and stored for later
use in reclamation and revegetation.
Some operations store extracted ore in stockpiles until they are beneficiated as directed by the
operator's mining, operating, or production plan. These piles may be located in or outside the pit.
In some cases, low-grade ore may never be beneficiated and. become waste at closure. Ore and sub-
ore piles are typically unlined. States may or may not have required run-on/runoff controls for these
piles; however, they are not required. Constituents of concern for waste rock and ore piles include
low concentrations of radionuclides as well as sulfur-bearing minerals that, under certain conditions,
may generate acid and, thus, leach metals.
1.5.2.2 Mine Pits and Underground Workings
In addition to wastes generated during active operations, when the mines close or stop production,
pits and underground workings may be allowed to fill with water, since the need for dewatering is
gone. (Mine water generated during the active life of a mine is usually not considered to be a waste;
however, it is generally considered waste after mine closure.) Radionuclide concentrations are likely
to be elevated in mine water (collected in abandoned pits or underground workings, and in
discharges) and acid generation may be a problem, depending on local geochemistry. Abandoned
underground mines and mine shafts may be unprotected, and the surface above the mine may, with
time, subside, though this is mostly a problem with historical mines. Deficiencies in mine shaft
protection may be caused by the use of unsuitable materials, such as inadequate shaft cappings, or by
unexpected occurrences that break capping seals, such as water surges in flooded mines (US DOI,
Bureau of Mines 1983a).
1.5.2.3 Tailings Impoundments
The requirements for tailings impoundments at operational active mills changed with Title II of
UMTRCA. Among other things, UMTRCA banned the use of mill tailings for off-site construction,
the most significant pathway for human exposure to radionuclides (USEPA, 1983b Vol 2). Through
UMTRCA, the NRC requirements for tailings ponds at active mills include impermeable liners to
control the migration of liquids and soluble constituents, and adequate closure at the termination of
milling operations. Prior to UMTRCA, impoundments were frequently unlined and reclamation
(closure) requirements would have been dependant on State requirements.
Two general classifications of structures may be used to describe a tailings impoundment: water/
slurry retention dams and raised embankments. The choice of impounding structure is influenced by
the characteristics of the mill tailings, beneficiation effluents, and area geology and topography. The
size of tailings impoundments varies between operations and may range up to hundreds of acres. No
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Mining Industry Profile: Uranium
information was obtained on the number or sizes of evaporation ponds or on closure/reclamation
practices.
1.5.2.4 Evaporation Ponds
Evaporation ponds are used by conventional milling operations to dispose of process water or other
solutions that are unsuitable for discharge or undesirable for addition to the tailings impoundment.
Wastes directed to evaporation ponds include barren leach, solvent exchange and ion exchange
solutions. Bentonite or synthetic liners are typically installed to prevent the migration of fluids from
the pond. Sludges removed from evaporation ponds are deposited in the tailings impoundment. No
information was obtained on the number or sizes of evaporation ponds or or closure/reclamation
practices.
1.5.2.5 Settling Ponds
Settling ponds are employed at in situ mining operations to remove radium from the bleed solution
prior to discharge. Waste process water may also be directed to settling ponds after passing through
an ion exchange or reverse osmosis circuit to remove the majority of contaminants. Barium chloride
is added to the bleed solution to precipitate the radium, bringing the effluent within NPDES
standards. The effluent can then be discharged via an NPDES permitted outfall or land applied.
During restoration, settling pond effluent may be pumped to a storage reservoir and ultimately
reinjected. Sludges removed from the settling ponds are containerized and shipped to NRC-licensed
disposal facilities.
1.5.2.6 Land Application Areas
Land application is used as a method of eliminating the volume of water generated in the bleed
solution during extraction and restoration phases of in situ mining. Land application discharges are
permitted (in Wyoming) as a form of wastewater treatment and are required 1.0 meet NPDES
discharge standards. The effluent is typically discharged to native grasslands used for grazing or hay
production. Volumes of discharges were not determined.
1.5.2.7 Deep Disposal Wells
Since in situ mining operations usually do not operate a tailings impoundment:, an alternative source
for disposal of wastes is necessary. Deep disposal wells are often used to dispose of wastes that
cannot be recycled, treated, and/or discharged. Brines generated by reverse osmosis treatment,
laboratory wastes and other wastes are typically injected. Operation of these wells is regulated under
the UIC program described in the Current Regulatory Framework section of Ihis report. Volumes
and characteristics of injected wastes were not determined.
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1.6 ENVIRONMENTAL EFFECTS
1.6.1 Introduction
Uranium has been associated with mining wastes since the late 1890s when it was discarded as
undesirable component in the mining of radium (and to a lesser extent, vanadium). Twelve mills
operated on the Colorado Plateau for different periods from 1901 through the late 1980s. Initially,
these mills beneficiated radium, although most if not all were also used for beneficiation of uranium
as the industry developed (MINOBRAS, 1978).
Nearly any portion of waste management units at active mines may be a potential source of
environmental contamination. Environmental effects resulting from uranium extraction and
beneficiation are chiefly derived from two sources: mining activities, and radionuclides present in the
wastes. Open pit mining activities may create environmental effects typical of surface disturbances:
increased runoff as well as increased erosion by wind and water. Dewatering operations conducted
by surface and underground mines may create groundwater depressions that may persist after mining
ceases. Potential environmental effects from in situ operations are primarily groundwater-related.
Since surface disturbance is not extensive, the impacts of surface operations associated with in situ
mining (e.g. drilling wastes, ponds) are not well documented.
Mill tailings, and particularly the radionuclides contained within, appear to be a major source of
environmental impact to air, soil, surface and groundwater. Findings in the Report to Congress:
Potential Health and Environmental Hazards of Uranium Mine Wastes indicated that the most serious
threat to human health was the use of uranium mill tailings in off-site construction. The Department
of Energy, through Title I of UMTRCA, is conducting remedial activities on tailings generated by 24
uranium mills throughout the western U.S. (except for one site in New Jersey). UMTRCA's Title II
licenses and places stringent requirements on operations and closure at currently operating (and
inactive) mills (USEPA, 1983a). For a discussion of UMTRCA, see the Current Regulatory
Framework section of this report.
A discussion of the potential environmental effects associated with uranium mining is presented in the
following sections. Specific examples from industry are included in this section, as appropriate.
Actual release incidents are described in Appendix A of this report.
This section does not purport to be a comprehensive examination of environmental damages that can
occur or that actually occur at mining operations. Rather, it is a brief overview of some of the
potential problems that can occur under certain conditions. The extent and magnitude of
contamination depends on highly variable site-specific factors that require a flexible approach to
mitigation. EPA is aware that many of the potential problems can be, and generally are, substantially
mitigated or avoided by proper engineering practices, environmental controls, and regulatory
requirements.
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1.6.2 Surface Water
1.6.2.1 Mine Dewatering
Surface and underground mines may be dewatered to allow extraction of ore. Dewatering can be
accomplished in two ways: (1) pumping from groundwater interceptor wells to lower the water table
and (2) pumping directly from the mine workings. At the end of a mine's active life, pumping
typically is stopped and the pit or underground workings are allowed to fill with water. The mine
water may be contaminated with radioactive constituents, metals, and suspended and dissolved solids.
Prior to being discharged, mine water from uranium mines is usually treated with a flocculent and
barium chloride to reduce suspended solids concentrations and to coprecipitate radium. The chemical
quality of mine waters differs from the receiving surface waters in several ways. For example, in the
Grants Mineral Belt of New Mexico, mine dewatering effluents have been documented to contain
elevated concentrations of gross alpha and beta particles; radionuclides radium-226 and lead-210;
natural uranium; molybdenum; selenium; and dissolved solids, sulfate in particular. On occasion,
arsenic, barium and vanadium are detected (Gallaher and Longmire, 1989). When mine water is
discharged to surface waters, it can change the quality of the surface water. Elevated concentrations
of metals and radionuclides, constituents typical of mine waters, have been detected in surface waters
near uranium mines (EPA, 1983).
In arid climates, like New Mexico, the discharge of mine water to a receiving stream can completely
change the hydrologic conditions of the receiving body. Typically, mine water is discharged to
ephemeral streams in arid climates. The mine waters have, in some instances, transformed ephemeral
streams to perennial streams. These newly created perennial streams often lose flow to subsurface
alluvial material which recharges shallow alluvial aquifers. Studies have documented that infiltration
of uranium mine dewatering effluents have been accompanied by a gradual change in the overall
chemistry of the groundwater, and the groundwater now bears a greater resemblance to the mine
dewatering effluent (Gallaher and Longmire, 1989).
The quality of mine water depends upon the dewatering method used. Water removed from wells
adjacent to the mine usually is representative of natural groundwater quality, at least while dewatering
continues. Mine water removed from the mine, however, can be high in radionuclides, metals, and
dissolved solids (EPA, 1984). Practices such as recycling mine water to the mill helps reduce the
impacts of mine water to surface water bodies.
1.6.3 Groundwater
Potential and documented effects on groundwater from uranium mining activities vary with the type of
activity being conducted. Operation of open pit and underground mines potentially influence
groundwater through dewatering operations and through approved discharges as discussed in the
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alpha activity. Additionally, arsenic, iron, selenium, radium and total solids exceeded drinking water
maximum Contaminant limits (MCLs) at some sites (USEPA, 1987). The degree of migration is
related to numerous factors including the chemistry of the tailings material; the permeability of the
impoundment and liner (if present); the amount of precipitation; the' nature of the underlying soils;
and the proximity to both surface and ground water.
Environmental effects associated with early in situ leaching operations occurred as a result of lixiviant
selection. Early lixiviants included acid solutions and ammonium carbonates. Restoration of aquifers
leached with acid lixiviants proved difficult as pH levels were difficult to raise after being dropped.
Aquifers leached with ammonium lixiviants were also difficult to restore as the ammonium ions
readily attached to clay particles within the production zone and were difficult to remove (Bureau of
Mines, 1981b).
Extraction and restoration techniques have evolved and improved since in situ techniques were first
employed. Carbon dioxide and oxygen are commonly used as the lixiviant in current in situ
operations; recovery of the lixiviant itself, may not be a serious problem. However, restoration must
remove or otherwise neutralize the oxidant in order to restore chemical stability within the aquifer.
Recovery of the lixiviant and solubilized constituents at the end of the extraction operation can be
complicated if the lixiviant migrates to an area that has poor hydraulic connections to the rest of the
production zone. Lixiviant in these hydraulic "dead ends" may continue to solubilize enough
constituents to preclude attainment of baseline parameters (Osiensky and Williams, 1990). This type
of effect is typically limited to specific wells or portions of the production zone rather than entire
production zones.
Although carbon dioxide and oxygen do not constitute contaminants of an aquifer, they function to
oxidize and solubilize uranium (and other) constituents of the production zone. Once solubilized, the
potential exists for migration of these constituents out of the production zone. Migration of
solubilized minerals or lixiviant out of the production zone is termed an excursion. The severity of
an excursion is dependant on the constituents involved (all solubilized constituents do not necessarily
migrate), the use class of the affected aquifer, and the extent of the excursion. Detecting excursions
may be complicated by the fact that constituents that have been solubilized may migrate out of the
production zone and become reduced or precipitate prior to reaching a monitoring well. For this
reason, selection of adequate parameters for use as upper control limits (UCLs) is critical (NRC,
1986).
In 1986, the NRC conducted an analysis of excursions at in situ mines in Wyoming and Texas. The
percentage of excursions reported for individual wells compared to all operational wells was not
discerned. The frequency of excursions was also not determined although the duration may range
from a period of days to more that two years (in one case). The study found that the incidence of
vertical excursions can be reduced by fully investigating the integrity of the aquifer prior to initiating
41
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Mining Industry Profile: Uranium
surface water section above. Tailings impoundments associated with, conventional mills have the
potential to leak; while some of the liquid constituents of the tailings are recycled or evaporated,
unlined tailings ponds may allow liquids to seep into the ground, eventually reaching groundwater.
This is also true for evaporation and radium settling ponds, although some States require liners in all
wastewater ponds.
In situ operations inject lixiviant into what is termed the production zone, normally a sandstone
aquifer. The potential impacts of these operations result from the increased solubility of uraniferous
and other compounds, which facilitates migration of these species into neighboring aquifers. As a
result, complete restoration of mined aquifers is not necessarily a simple task.
Dewatering operations at open pit and underground mines may impact local aquifers through
drawdowns in the direct vicinity of the mine with (presumably) little lasting effect. However,
depending on the transmissivity of the aquifer, the size of the dewatering operation, and the number
of mines actively conducting dewatering, impacts to aquifers may be significmt. Mining activity
from 1970 through 1984 near the Everest Minerals' Highland Uranium Project reportedly withdrew
39,000 acre-feet of water. Although the extent of the drawdown was not staled, a 1991 Wyoming
Department of Environmental Quality document reported that the potentiometric surface within the
area was "recovering" (WDEQ, 1991).
It should be noted that groundwater impacted or potentially impacted by mining activities is not
necessarily suited for domestic use prior to mining. For example, aquifers containing uranium ores in
both Wyoming and New Mexico have been documented as having elevated levels of uranium and
other radionuclides prior to the initiation of mining activities (WDEQ, 1991; Eadie and Kaufmann,
1977).
Dewatering activities in the Grants Mineral Belt, as discussed in the previous section, has impacted
both surface water and alluvial aquifers. Streams receiving mine effluent had higher than baseline
concentrations of uranium, radium, lead, selenium, and molybdenum. Studies completed as recently
as 1986 indicate that the shallow aquifers underlying these streams had begun to chemically resemble
mine water; concentrations of those constituents that may migrate (uranium, selenium, molybdenum)
were higher than in "natural waters" (Gallaher and Longmire, 1989). The extent of recovery of both
surface and shallow groundwater in the Grants Mineral Belt, following the decline of uranium mining
activities in the early 1980s, was not determined.
Mill sites covered under Title I of UMTRCA have been investigated to determine the extent of
migration of tailings constituents. Migration of uranium and other tailings constituents occurs through
leaching (percolation of precipitation) and erosion. Migration caused at least local contamination of
groundwater at all of the 24 sites investigated. The following groundwater quality parameters at these
sites were most frequently exceeded: uranium, molybdenum, manganese, nitrate, sulfate, and gross
40
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Mining Industry Profile: Uranium
surface water section above. Tailings impoundments associated with conventional mills have the
potential to leak; while some of the liquid constituents of the tailings are recycled or evaporated,
unlined tailings ponds may allow liquids to seep into the ground, eventually reaching groundwater.
This is also true for evaporation and radium settling ponds, although some States require liners in all
wastewater ponds.
In situ operations inject lixiviant into what is termed the production zone, normally a sandstone
aquifer. The potential impacts of these operations result from the increased solubility of uraniferous
and other compounds, which facilitates migration of these species into neighboring aquifers. As a
result, complete restoration of mined aquifers is not necessarily a simple task.
Dewatering operations at open pit and underground mines may impact local aquifers through
drawdowns in the direct vicinity of the mine with (presumably) little lasting effect. However,
depending on the transmissivity of the aquifer, the size of the dewatering operation, and the number
of mines actively conducting dewatering, impacts to aquifers may be significant. Mining activity
from 1970 through 1984 near the Everest Minerals' Highland Uranium Project reportedly withdrew
39,000 acre-feet of water. Although the extent of the drawdown was not stated, a 1991 Wyoming
Department of Environmental Quality document reported that the potentiometric surface within the
area was "recovering" (WDEQ, 1991).
It should be noted that groundwater impacted or potentially impacted by mining activities is not
necessarily suited for domestic use prior to mining. For example, aquifers containing uranium ores in
both Wyoming and New Mexico have been documented as having elevated levels of uranium and
other radionuclides prior to the initiation of mining activities (WDEQ, 1991; Eadie and Kaufmann,
1977).
Dewatering activities in the Grants Mineral Belt, as discussed in the previous section, has impacted
both surface water and alluvial aquifers. Streams receiving mine effluent had higher than baseline
concentrations of uranium, radium, lead, selenium, and molybdenum. Studies completed as recently
as 1986 indicate that the shallow aquifers underlying these streams had begun to chemically resemble
mine water; concentrations of those constituents that may migrate (uranium, selenium, molybdenum)
were higher than in "natural waters" (Gallaher and Longmire, 1989). The extent of recovery of both
surface and shallow groundwater in the Grants Mineral Belt, following the decline of uranium mining
activities in the early 1980s, was not determined.
Mill sites covered under Title I of UMTRCA have been investigated to determine the extent of
migration of tailings constituents. Migration of uranium and other tailings constituents occurs through
leaching (percolation of precipitation) and erosion. Migration caused at least local contamination of
groundwater at all of the 24 sites investigated. The following groundwater quality parameters at these
sites were most frequently exceeded: uranium, molybdenum, manganese, nitrate, sulfate, and gross
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Mining Industry Profile: Uranium
alpha activity. Additionally, arsenic, iron, selenium, radium and total solids exceeded drinking water
maximum Contaminant limits (MCLs) at some sites (USEPA, 1987). The degree of migration is
related to numerous factors including the chemistry of the tailings material; the permeability of the
impoundment and liner (if present); the amount of precipitation; the nature of the underlying soils;
and the proximity to both surface and groundwater. (For updated information, see 60 Federal
Register 2854, January 11, 1995, which is attached in Appendix C).
Environmental effects associated with early in situ leaching operations occurred as a result of lixiviant
selection. Early lixiviants included acid solutions and ammonium carbonates. Restoration of aquifers
leached with acid lixiviants proved difficult as pH levels were difficult to raise after being dropped.
Aquifers leached with ammonium lixiviants were also difficult to restore as the ammonium ions
readily attached to clay particles within the production zone and were difficult to remove (Bureau of
Mines, 1981b).
Extraction and restoration techniques have evolved and improved since in situ techniques were first
employed. Carbon dioxide and oxygen are commonly used as the lixiviant in current in situ
operations; recovery of the lixiviant itself, may not be a serious problem. However, restoration must
remove or otherwise neutralize the oxidant in order to restore chemical stability within the aquifer.
Recovery of-the lixiviant and solubilized constituents at the end of the extraction operation can be
complicated if the lixiviant migrates to an area that has poor hydraulic connections to the rest of the
production zone. Lixiviant in these hydraulic "dead ends" may continue to solubilize enough
constituents to preclude attainment of baseline parameters (Osiensky and Williams, 1990). This type
of effect is typically limited to specific wells or portions of the production zone rather than entire
production zones.
Although carbon dioxide and oxygen do not constitute contaminants of an aquifer, they function to
oxidize and solubilize uranium (and other) constituents of the production zone. Once solubilized, the
potential exists for migration of these constituents out of the production zone. Migration of
solubilized minerals or lixiviant out of the production zone is termed an excursion. The severity of
an excursion is dependant on the constituents involved (all solubilized constituents do not necessarily
migrate), the use class of the affected aquifer, and the extent of the excursion. Detecting excursions
may be complicated by the fact that constituents that have been solubilized may migrate out of the
production zone and become reduced or precipitate prior to reaching a momtoring well. For this
reason, selection of adequate parameters for use as upper control limits (UCLs) is critical (NRC,
1986).
In 1986, the NRC conducted an analysis of excursions at in situ mines in Wyoming and Texas. The
percentage of excursions reported for individual wells compared to all operational wells was not
discerned. The frequency of excursions was also not determined although the duration may range
from a period of days to more that two years (in one case). The study found that the incidence of
41
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Mining Industry Profile: Uranium
vertical excursions can be reduced by fully investigating the integrity of the aquifer prior to initiating
extraction. Additionally, the study indicated that once excursions occur, horizontal excursions are
more readily controlled than vertical excursions (NRC, 1986).
1.6.4 Air
1.6.4.1 Radon
Underground uranium mines produce exhaust, which typically has Radon-222 in measurable
concentrations. Radon-222 is present in the exhaust because it emanates from the ore. The
concentration of Radon-222 in mine exhaust varies depending upon ventilation rate, mine volume,
mine age, grade of exposed ore, size of active working areas, moisture content and porosity of rock,
barometric pressure, and mining practices. A previous EPA study indicates that higher Radon-222
emission rates occur at older mines, probably because there are larger surface areas of exposed ore
and subore. By properly capping the exhaust vents and sealing the shaft and mine entrances with
bulkheads, radon emission rates from inactive or closed underground mines can be dramatically
reduced (EPA, 1983a).
Aboveground sources of radon-222 at both underground and surface extraction and beneficiation
operations include exhalation from ore, waste rock, overburden (at surface mines only), and tailings.
The amount of radon that emanates from these materials into the surrounding atmosphere can depend
upon, among other things, the exposed surface area of the units in which the materials are located;
the grade of material; the control mechanisms used; and, in the case of tailings, the method of
deposition (EPA, 1983).
Radon also escapes from drill holes. When the development drill penetrates the ore body, the ore and
sub-ore formations in the drill hole become exposed to air. Consequently, the radon emanates from
the ore into the drill hole and can escape into the atmosphere (EPA, 1983a).
1.6.4.2 Fugitive Dust
A primary source of air contamination at mine sites are fugitive dust emissions from mine pits and
underground workings, overburden, mine rock dumps, ore, sub-ore, and haul roads. Tailings may
also be a potential source of fugitive dust when particulates are transported by wind. Dust emissions
vary depending upon moisture content, amount of fines, number and types of equipment operating,
and climate. The movement of large haul trucks can be a source of dust at most uranium mines. To
minimize fugitive dust, haul roads are frequently sprinkled with water during dry periods or dust
suppressants are applied. During the active life of the mine, water may be applied to these piles to
control dust and prevent entrainment. After mine closure, revegetation or other stabilizing methods
may be used to control dust. The potential contaminants are heavy metals and other toxics (EPA,
1983).
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Mining Industry Profile: Uranium
1643 Soils
The migration of radionuclides from mining or beneficiation operations into the soil can cause an
increase in radioactivity of soils. It was found that radium-226 and, to a lesser extent, thonum-232
can adsorb into the structure of clay particles. These entities can also be desorbed by low
concentration salt solutions (USBOM, 1984). Any metals that are preseni in waste rock, sub-ore, or
tailings can be leached to the surrounding soil.
Environmental effects of uranium mining activities on soils includes those derived from surface
disturbances. The most extensive soil disturbances are created by surface mines although surface
facilities constructed for underground or in situ mining operations also impact soil, including a loss of
vegetation cover. Loss of vegetation cover typically results in increased erosion rates unless measures
are taken to stabilize topsoil and divert surface runoff from disturbed areas.
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Mining Industry Profile: Uranium
1.7 CURRENT REGULATORY FRAMEWORK
1.7.1 Introduction
Uranium mining activities must meet the requirements of both Federal and state regulations. The first
part of this chapter addresses both the primary statutes that give Federal agencies the authority to
regulate these activities and the regulations themselves. The latter portion of the chapter presents the
regulatory programs of Texas and Wyoming to serve as examples of how State regulatory programs
apply to uranium extraction and beneficiation.
The statutes (and associated regulations) that this chapter examines include: the Clean Water Act
(CWA), as amended (33 USC 1251 et seq); the Clean Air Act (CAA), as amended (42 USC 7401 et
seq); The Safe Drinking Water Act (SOWA), as amended (42 USC 300 (f) et seq); and the Atomic
Energy Act (AEA) (42 USC 2021 et seq), as amended by the Uranium Mill Tailings Radiation
Control Act (UMTRCA) (72 USC 7901 et seq). The primary Federal agencies responsible for
implementing the aforementioned statutes include: the Environmental Protection Agency (EPA), the
Nuclear Regulatory Commission (NRC), and the Department of Energy (DOE). The paragraphs
below introduce each of the major statutes, which are described in more detail in subsequent sections.
The CAA gives EPA the authority to regulate emissions of both "conventional" pollutants, like PM10
(paniculate matter less than 10 microns) and hazardous pollutants, such as radon. Both of these air
pollutants are emitted by uranium extraction and beneficiation activities.
The CWA gives EPA the authority to impose effluent limits, via permits, on point-source discharges,
including those from during uranium extraction and beneficiation operations, to waters of the U.S. It
also gives EPA the authority to regulate, through permits, storm water discharges from both inactive
and active mine sites.
EPA established an Underground Injection Control
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Mining Industry Profile: Uranium
licensing active uranium mills and licensing inactive uranium tailings site:, that have undergone
remediation. Although the NRC has promulgated radiation protection standards that regulate active
and inactive uranium milling sites, the NRC has no regulatory authority ever uranium mines, except
the aboveground activities of solution mines. The sections below more fully explore the regulatory
roles of each of the aforementioned agencies.
The authority of State agencies to regulate uranium extraction and beneficiation activities comes from
two sources, Federally delegated programs and State statutory authority. The Federal programs
applicable to uranium extraction and beneficiation activities that can be delegated to the States include:
the UIC program, the NPDES program, and NRC licensing and radiation protection standards. In
order for a State to be able to administer any or all of these Federal programs, the State must have
requirements that are at least as stringent as the respective Federal programs.
1.7.2 Federal Regulatory Program
1.7.2.1 The Uranium Millings Tailings Remediation Control Act
The U.S. Government began to purchase uranium for defense
purposes in the early 1940s. Since that time, large quantities of
tailings have been generated by the uranium milling industry. In
many cases, these tailings have been dispersed from impoundments
and piles by natural forces and by humans for construction use in or
around buildings or for roads. UMTRCA, which in 1978 amended
the AEA, established two programs to protect the public health,
safety and the environment from uranium mill tailings. Title I of
UMTRCA addresses 22 Congressionally designated sites (to which
DOE added two more) that are now inactive (e.g., all milling has
stopped and the site is not licensed by the NRC). A list of these
sites can be found in the box below. Title H of UMTRCA
addresses active sites (those with NRC or Agreement State licenses)
(48 FR 45926).
Risks Posed "by Uranium Mill Tailings
UMTRCA Title I Sites
Salt Lake City, UT
Onsen River, UT
Mexican Hat, UT
Du range, CO
Grzmd Junction, CO
Rifle, CO (two sites)
Naiurita, CO
Maybell, CO
Slick Rock, CO (two sites)
Shiprock, NM
Ambrosia Lake, NM
Riverton, WY
Converse County, WY
Lakeview, OR
FaH* City, TX
Tuta City, AZ
Monument Valley, AZ
Lo%rtnan, ID
Carnonsburg, PA
Edgemont, SD
Bowman/Belfield, SD
Uranium occurs in various minerals as one of three isotopes: U-234, U-23:5, and the most abundant of
the isotopes, U-238. Yellowcake is a generic term used to describe the yellow powder generated as
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Mining Industry Profile: Uranium
the end product of uranium beneficiation. The purity of yellowcake typically ranges from 60 to 75
percent U3O8.'
Historically, conventional uranium mining consisted of extracting uranium bearing rock, then
crushing, grinding, and froth flotation to produce a uranium concentrate yellowcake. This milling
process generated large volumes .of tailings which were disposed of in tailings impoundments.
Radium-226, thorium-230, and radon-222 (gas) are the radionuclides present in uranium mill tailings
that are of principle concern to human health and the environment. In American Mining Congress v.
Thomas (AMC I), the court recognized the dangers to human health and the environment from
uranium mill tailings when it stated that:
[r]adium decays to produce radon. Radon is an inert gas, some of which escapes from the
tailings particles into the atmosphere. Airborne radon degrades into a series of short half-life
decay products that are hazardous if inhaled. If the radon gas does not escape the mill
tailings piles, its decay products remain in the piles and produce gamma radiation, which ma>
be harmful to people and animals living near the mill tailings piles. Uranium mill tailings
also contain potentially dangerous nonradioactive materials such as arsenic and selenium.
These toxic and radioactive materials may be ingested with food or water.2
Uranium has primarily been mined in the western United States; Arizona, Colorado, New Mexico,
South Dakota, Texas, Utah, Washington and Wyoming. A total of 14 uranium mines were
operational in 1991; six underground mines, two open pits, and six in-situ facilities. Uranium was
also produced to a limited extent as a byproduct of phosphoric acid production at two sites in Florida
and one in Louisiana.3 Both Florida sites no longer produce uranium but are still operating as
producers of phosphoric acid.
Regulatory Structure
A complex set of federal and state regulations are applicable to uranium mining and processing.
These include the Atomic Energy Act (AEA)4, as amended by the Uranium Mill Tailings Radiation
1 Merritt, R.C. 1971. The Extractive Metallurgy of Uranium. Colorado School of Mines,
Golden, CO.
2 American Mining Congress v. Thomas (AMC I), 772 F.2d 617, 621 (10th Cir. 1985), cert.
denied. 476 U.S. 1158 (1986). See also 48 Fed. Reg. 590, 592 (1983). See generally Environmental
Protection Agency, Final Environmental Impact Statement for Remedial Action Standards for Inactive
Uranium Processing Sites 3-68 (1982).
3 Domestic Uranium Mining and Milling Industry 1992, Viability Assessment. U.S. Department
of Energy, Energy Information Administration, 1993. DOE/EIA-0477(92), Distribution Category UC-
98, Washington, DC.
4 42 U.S.C. § 2021 et seq
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Mining Industry Profile: Uranium
Control Act (UMTRCA)5; the Clean Air Act (CAA)6; the Clean Water Act (CWA)7; and the Safe
Drinking Water Act (SDWA)8.
The primary federal agencies responsible for implementing these statutes include: the Nuclear
Regulatory Commission (NRC) the Environmental Protection Agency (EPA) and the Department of
Energy (DOE).
The Uranium Millings Tailings Remediation Control Act
In many cases, uranium mill tailings have been dispersed from impoundments and piles by natural
forces and by humans for construction use in or around buildings or for roads. UMTRCA established
two programs to protect the public health, safety and the environment from uranium mill tailings.
Title I of UMTRCA addresses 24 inactive sites. An inactive site means that all milling has stopped
and the site is not licensed by the NRC. Title II of UMTRCA addresses active sites that are required
to have a license from NRC or an Agreement State.9
Title I of UMTRCA10
Title I defines tailings at inactive uranium
milling sites as residual radioactive material. It
requires the cleanup of offsite tailings and the
long-term control of tailings piles. DOE was
charged with remediating these designated sites,
with the full cooperation and participation of the
states, to achieve compliance with standards
prescribed by EPA. EPA has promulgated final
health and environmental standards to govern
stabilization, control, and clean up of residual
radioactive materials (primarily mill tailings) at «••
inactive uranium processing sites." The DOE
must meet these standards when remediating Title I sites.
Residual radioactive material t& determined by the Secretary
of Energy to be radioactive and can be either:
(I) Waste in the form of tailings resulting from fee
processing of ores for the extraction of uranium and other
valuable constituents of the ores; or
(2) Other waste at a processing site which relates to such
processing, including any residual stock of unprocessed ores
or low-grade materials.
This terra is used only with respect to materials at sites
subject to remediation under Title I of UMTRCA.
3 72 U.S.C. § 7901 et seq
6 42 U.S.C. § 7401 et seq
7 33 U.S.C. § 1251 etseq
8 42 U.S.C. § 300 (f) et seq
9 A state can apply for and obtain permission from the NRC to become an Agreement State under
AEA § 274(a), 42 U.S.C. § 2021(a). Otherwise, NRC exclusively regulates source, special nuclear,
and byproduct material. As part of obtaining Agreement status, a state must demonstrate that its
statutes and regulations conform to NRC requirements. 42 U.S.C. § 2021(d)(2).
10 42 U.S.C. § 7918.
11 40 C.F.R. 192 (1992).
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Mining Industry Profile: Uranium
EPA promulgated standards for two types of remedial actions: control and cleanup. Control places
tailings in a situation that will minimize their long-term risk to humans. Cleanup reduces the
potential health risks resulting from dispersed tailings. All remedial actions must be selected and
performed with the concurrence of the NRC. Upon completion of the remedial action at the 24
designated sites, the NRC must issue a license to ensure that public health and the environment are
protected. The license may require DOE to conduct monitoring, maintenance, or any other actions
the NRC deems necessary.12
The Uranium Mill Tailings Remedial Action Amendments Act of 1988 provides an extension of the
UMTRCA Title I deadline for the DOE to finish remediating the 24 designated sites. It allowed DOE
until Sept 30, 1994 (previously 1990) to perform remedial actions at designated sites. The authority
to perform groundwater restoration was extended without limitation.
The court in AMC I upheld most of EPA's standards except for the groundwater provisions of Title I
regulations.13 EPA is currently issuing new groundwater standards as a result of AMC 7.14 The
previous standards for Title I sites were in the form of qualitative groundwater guidance in which
DOE chooses the constituent concentration levels that groundwater must meet. When AMC I
remanded EPA's standards, it instructed EPA "to treat these toxic chemicals that pose a groundwater
risk as it did in the active mill site regulations."15 In 1987, NRC promulgated final rules for
groundwater protection at uranium mill tailings sites that conform to provisions of EPA's standards
for groundwater protection at 40 C.F.R. § 192(d) and (e).16 UMTRCA required agencies to use the
available proposed standards until final ones were promulgated.17
In 1995, EPA issued final regulations to correct and prevent contamination of groundwater beneath
and in the vicinity of inactive uranium processing sites by uranium tailings.18 The regulations apply
to tailings at 24 locations that qualify for remedial action. They provide that tailings must be
stabilized and controlled in a manner that permanently eliminates or minimizes contamination of
groundwater beneath stabilized tailings, so as to protect human health and the environment. They also
provide for cleanup of contamination that occurred before the tailings are stabilized. The rule also
establishes groundwater protection standards that include a list of specific hazardous constituents
relevant to each waste management area, a concentration limit for each hazardous constituent, the
point of compliance, and the compliance period.
12 55 Fed. Reg. 45,591 (1990).
13 American Mining Congress v. Thomas, 772 F.2d 617 (10th Cir. 1985), cert, denied. 476 U.S.
1158 (1986). Title I regulations are found in 40 C.F.R. 192.20(a)(2)-(3).
14 60 Fed. Reg. 2854 (1995).
15 AMC I, 772 F.2d 617, 640 (10th Cir. 1985).
16 52 Fed. Reg. 43,553 (1987).
17 See AMC I at 623. See also 55 Fed. Reg. 45,591 (1990).
18 60 Fed. Reg. 2854 (1995).
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Mining Industry Profile: Uranium
EPA promulgated final standards for the control of residual radioactive material from non-operational
uranium processing sites designated in Title I of UMTRCA in Subpart A of 40 C.F.R. § 192. 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.
These standards require that the remediation:
• be designed to be effective for up to one thousand years to the extent reasonably
achievable, but at a minimum for 200 years,
• provide reasonable assurance that releases of radon-222 from residual radioactive material
to the atmosphere will not exceed an average release rate of 20 Pci/m2/s,
• provide reasonable assurance that releases of radon-222 from residual radioactive material
will not increase the annual average concentration of radon-222 in air by more than one-
half picocurie per liter.
Under Subpart B of 40 C.F.R. § 192, EPA promulgated final standards for the cleanup of land and
buildings contaminated with residual radioactive materials at the 24 designated inactive uranium
processing sites. "EPA requires that remedial actions be conducted to provide reasonable assurance
that, as a result of residual radioactive materials from any designated processing site:19
• The concentration of radium-226 in land, averaged over any area of 100 square meters
shall not exceed the background level by more than:
5 picocuries per gram (Pci/g), averaged over the first 15 cm of soil below the surface.
15 Pci/g averaged over 15 cm thick layers of soil more than 15 cm below the surface.
• In any occupied or habitable building: m^^m^g^mm<^n^m^f*^B*^^^^
WL (working level) is;
™ ,. . - , ... . "Any combination of short-lived radon decay products
- The objective of the remedial action -m one lter of ^ tot wifl result ^ ^ ultimate
shall be, and reasonable effort Shall emission of alpha particles with a total energy of 130
be made to achieve, an annual billion electron vofts," {40 CFR 192)
average radon decay product mmmimmilliimmmmiimmlimmmtililf^fmit^i^
concentration (including background)
not to exceed 0.02 WL. Regardless, the radon decay product concentration, including
background shall not exceed 0.03 WL.
The level of gamma radiation shall not exceed the background level by more than 20
microroentgens per hour.
Subpart C of 40 C.F.R. § 192 allows DOE, with NRC concurrence, to apply supplemental standards
in lieu of the standards in Subparts A and B. Before using these supplemental standards, certain
conditions must be present; for example, the remedial actions required to satisfy Subpart A or B pose
a clear risk of injury to workers or to members of the public.
19 40 C.F.R. § 192(b) (1992).
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Mining Industry Profile: Uranium
Title II of UMTRCA20
Title II of UMTRCA applies to currently operating uranium mill tailings facilities licensed by the
NRC or an Agreement State. Title II regulates uranium byproduct materials such as mill tailings at
operating sites. The Title II program contains requirements for a final disposal of tailings, the control
of effluents into groundwater, and radon emissions during and after milling operations. UMTRCA
required EPA to establish standards for operating sites in a manner consistent with standards
established under Subtitle C of the Solid Waste Disposal Act, as amended.21 However, the tailings
as a substance are exempt from EPA's RCRA Subtitle C regulations.22
The standard setting requirements are divided into two parts. The first part applies to the
management of tailings during the active life of the pile and during the subsequent closure period,
which begins after cessation of milling operations but prior to completion of final disposal. The
second part specifies standards for after the piles are closed, which govern the design of disposal
systems.23 The site must be closed in a manner that meets applicable NRC standards before the
NRC or Agreement State terminates the operating license and issues a long-term care license.24 The
NRC requires a detailed Long-Term Surveillance Plan (LTSP) from DOE or an appropriate State
which addresses ownership (whether Federal or State), disposal site conditions, the surveillance
program, required follow-up inspections, and how and when emergency repairs and, if necessary
planned maintenance, will be accomplished.25
In 1983, EPA proposed general environmental standards for uranium and thorium mill tailings sites
licensed by NRC or one of its Agreement States.26 The NRC published amendments to 10 C.F.R. §
40 to conform its rules to EPA's general standards in 40 C.F.R. § 192, as it affected matters other
than ground water protection.27
EPA promulgated final rules in Subpart D of 40 C.F.R. § 192 to establish standards for the
management of uranium byproduct materials at Title II sites, pursuant to § 84 of the AEA, as
20 42 U.S.C. § 2022.
21 42 U.S.C. §§ 6901-6992k.
22 There is no permit required by EPA for the disposal of byproduct material. 42 U.S.C. §
2022(b)(2). Additionally, uranium tailings are exempt from RCRA Subtitle C regulations (hazardous
wastes) by 40 C.F.R. § 261.4(b)(7) (1992).
23 58 Fed. Reg. 32,174(1993).
24 55 Fed. Reg. 45,591 (1990).
25
Id.
26 48 Fed. Reg. 19,584 (1983). Final standards were published in 48 Fed. Reg. 45926 (1983) and
codified in 40 C.F.R. § 192(D) and (E).
27 50 Fed. Reg. 41,852(1985).
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Mining Industry Profile: Uranium
amended. Industry petitioners challenged these •^••••^•^^••^•^^^^•••^••••M^^B
rules in American Mining Congress v. Thomas Byproduct material means the tailings or wastes produced by
/.i«.»/-' m •>.* -r.. . ,^ ,, /- j L. r-r.A tne extraction or concentration of uranium from any ore
(AMC II). -* The AMC II court found that EPA proces$ed prjmarjly for jts source matena, coment;including
need not make a finding of a "significant risk" discrete surface wastes resting from uranium solution
prior to promulgating regulations for mill extraction processes. Underground ore bodies depleted by
tailings; that EPA may issue standards to apply such solution extraction operations do not constitute
within the boundaries of the mill sites; that the "byproduct material" (40 C'FR 192).
standards do not unlawfully compel specific •^•^^•••^•^•••^^••^•^•^•^^^•B
engineering and design methods by the implementing agencies; and that EPA properly considered cost
and benefit factors in establishing these standards.29
Uranium byproduct materials include the tailings or wastes produced by the extraction or
concentration of uranium. The final standards address both uranium ore processing operations and
closure and post-closure for uranium byproduct management facilities. The uranium ore processing
operation standards require:
• impoundments containing uranium byproduct material such as tailings to meet design
criteria established by EPA for owners and operators of hazardous waste treatment, storage
and disposal (TSD) facilities30
• managing uranium byproduct materials to conform to:
a combined radium-226 and radium-228 standard of 5 Pci/l,
a gross alpha-particle activity (excluding radon and uranium) standard of 15 Pci/l for
groundwater,
the groundwater protection standards31 and the monitoring requirements32 that were
established for owners and operators of hazardous waste TSD facilities,
the Environmental Radiation Protection Standards for Nuclear Power Operations33,
and
28 American Mining Congress v. Thomas (AMC II), 772 F.2d 640 (10th Cir. 1985) 16 Envtl. L.
Rep. 20,069.
29 Id.
30 40 C.F.R. § 264.221 (1992).
31.40C.F.R. §264.92(1992).
32 40 C.F.R. § 264.98 (1992).
33 40 C.F.R. § 190 (1992).
51
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Mining Industry Profile: Uranium
the Ore Mining and Dressing Point Source Category: Effluent Limitations Guidelines
and New Source Performance Standards, Subpart C, Uranium, Radium, and
Vanadium Ores Subcategory.34
Uranium byproduct management facilities must meet the following closure and post-closure
requirements:
• closure and post-closure requirements for nonradiological hazards, which EPA
promulgated for hazardous waste treatment storage and disposal facilities,35
• the disposal areas must be designed to provide reasonable assurance of effective control of
radiological hazards for at least 200 years, and
• the disposal areas must be designed to limit releases of radon-222 from uranium byproduct
materials to the atmosphere so as not to exceed an average release rate of 20 Pci/nr/s (the
same standard as for Title I sites). This requirement, however, is not applicable to any
portion of a disposal site that contains a concentration of radium-226 that, as a result of
uranium byproduct material, does not exceed the background level by more than:
5 Pci/g, averaged over the first 15 cm below the surface
15 Pci/g averaged over 15 cm thick layers more than 15 cm below the surface.
1.7.2.2 Nuclear Regulatory Commission
The NRC regulates active uranium milling and inactive uranium mill tailings disposal sites through
licenses. It does not regulate the actual mining of uranium, except the above ground activities
associated with solution mining. The NRC establishes its procedures
and criteria for the issuance of licenses to receive title to,
receive, possess, use, transfer, or deliver source and byproduct
materials.36 The authority for issuing these rules comes from
the AEA, Title II of the Energy Reorganization Act of 1974,
and Titles I and II of UMTRCA.
Source material is:
Uranium or thorium, or any
combination thereof, in any physical or
chemical form, or
In Quivira Mining Company v. NRC (Quivira Mining), the court
held that NRC can issue regulations under UMTRCA that
establish standards to follow in licensing and relicensing
• Ores which contain by weight one
twentieth of one percent (0.05%) or
more of:
- uranium
- thorium, or
- any combination thereof.
Source material does not include special
nuclear material, for example plutonium
or uranium 233 (10 CFR 40).
34 40 C.F.R. § 440 (1992).
3540C.F.R. §264.111 (1992).
36 10 C.F.R. § 40 (1992).
52
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Mining Industry Profile: Uranium
uranium mills and tailings sites.37 The Quivira Mining court also held that although NRC performed
no new cost-benefit studies in promulgating criteria for its rules, it reasonably relied on the
cost-benefit analysis performed by the EPA when it issued its active site regulations.38
In a similar case addressing NRC's implementing criteria from the 1987 amendments to UMTRCA,
American Mining Congress v. NRC (AMC III) held that the NRC properly considered the costs and
benefits of its 1987 amendments when it conformed the amendments to the EPA's UMTRCA
regulations concerning public health'and safety that had already assessed costs and benefits.39 The
AMC HI court held that since Congress has not stated whether the NRC must independently assess the
costs and benefits of its regulations and the NRC is required to conform to EPA's health and safety
regulations, NRC's interpretation of the UMTRCA is permissible and avoids replicating EPA's
properly conducted cost-benefit analysis.40 The AMC HI court also held that EPA acted permissibly
under the UMTRCA when it promulgated regulations that imposed RCRA requirements on uranium
mill tailings.4'
Remediated Nonoperating Uranium Mill Tailings Sites
The NRC has issued general licenses for Title I and Title II UMTRCA sites which have undergone
remediation. Title I UMTRCA sites, the 24 designated inactive sites, are not subject to any licensing
requirements during DOE's remediation, but Title II sites, the active sites, are subject to licensing
requirements. The general licenses are for custody and long-term care of:
• Residual radioactive material at uranium mill tailings disposal sites remediated under Title
I of UMTRCA
• Byproduct material at uranium or thorium mill tailings disposal sites regulated under Title
II of UMTRCA.
These general licenses become effective when the NRC accepts a site's Lo:ng-Term Surveillance Plan
(LTSP), from either the DOE or Agreement State. There is no termination of these general licenses.
The LTSP must contain procedures for establishing groundwater monitoring, groundwater protection
standards, inspections, and maintenance measures.
Operating Mill Tailings Sites
Operating mills and mill tailings sites must have site-specific NRC licenses! for possessing and using
source or byproduct material.42 The NRC requires the license applicant to file an application for
37 Quivira Mining Company v. NRC, 866 F.2d 1246 (10th Cir. 1989), 19 Envtl. L. Rep. 20,778.
38 Id.
39 American Mining Congress v. NRC (AMC III) 902 F.2d 781 (10th Cir. 1990) 20 Envtl. L.
Rep. 21,054.
40 Id.
41 Id.
42 10 C.F.R. § 40 (1992).
53
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Mining Industry Profile: Uranium
this license at least nine months prior to
commencing construction of a plant or facility
in which the activity will be conducted.43
Further, the NRC has determined that the
issuance of a license to possess and use source
material for uranium milling is a major federal
action which significantly affects the
environment.44 Therefore, pursuant to the
National Environmental Policy Act, an
Environmental Impact Statement must be
prepared and submitted with the license
application.
The license application must contain a proposed
decommissioning funding plan or a certification
of financial assurance for decommissioning.45
Each decommissioning funding plan must
contain a cost estimate for decommissioning and
a description of the method of financial
assurance.46 Each licensee must keep records
of information important to the safe and
effective decommissioning of the facility which
includes records of spills involving
Highlights of NRC's Appendix A Requirements:
• Permanently isolate tailings such that active
maintenance is not necessary,
• Comply with EPA's groundwater protection standards
in 40 CFR 192, Subpart D,
• Conduct monitoring, including groundwater
monitoring,
• Reduce all airborne effluent releases as low as
reasonable achievable, by means of emission controls
on mills and controlling dust from tailings piles,
• Establish financial surety to carry out
decontamination and decommissioning of the mill and
site, and for reclamation of tailings or waste disposal
areas,
• Mills must pay a minimum of $250,000 (1978
dollars) to US Treasury or appropriate State agency,
prior to license termination, for long-term
surveillance costs, and
* Title to the byproduct material licensed in this part
and land used for the disposal of this material must
be transferred to the US or to the State (at its option).
An application for a site-specific license must ••^•^•••^^••^^•^^••^^^^^^^™
contain proposed written specifications relating to milling operations and the final disposal of the
byproduct material to achieve the requirements that the NRC set forth in Appendix A of 10 C.F.R. §
40. Appendix A establishes technical, financial, ownership and long-term site surveillance criteria
relating to siting the operation, decontamination, decommissioning, and reclamation of mills and
tailings.
Radiation Protection Standards
Pursuant to the AEA and the Energy Reorganization Act of 1974, the NRC established standards for
protection against radiation hazards resulting from Title I and Title II activities licensed by the
NRC.48 The regulations establish standards for permissible doses, and levels and concentrations of
contamination.
47
43
Id.
44 10 C.F.R. § 51 (1992).
45 Id.
46 Id.
47 Id.
48 10 C.F.R. § 20 (1992).
54
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Mining Industry Profile: Uranium
radiation for restricted and unrestricted areas.49 They also establish precautionary procedures to be
implemented (e.g. personnel monitoring, caution signs, procedures for handling packages, instruction
of personnel and storage and control of licensed materials in unrestricted areas). Waste disposal
criteria are also established. For example, NRC requires tailings and associated waste to be disposed
of by transfer to an authorized recipient or by applying for NRC approval of proposed procedures to
dispose of licensed material.50 The regulations provide for criteria for disposal by release into
sanitary sewage systems and other methods.51 They also provide requirements for records, reports
and notification on radiation exposure of individuals for whom personnel monitoring is required; for
disposal of licensed materials; for theft or loss of licensed materials; and for notification of incidents
involving source material.52
Uranium Mill Tailings Sites Not Addressed Under UMTRCA
UMTRCA was enacted to provide remediation and protection from uranium tailings produced as a
result of government contracts but not private contracts.53 The 24 Title I sites have a special status
because of their government contract relationship and are explicitly provided funding for remediation
under UMTRCA. However, there are 12 private sites being addressed under Superfund that owe
their problems to uranium mill tailings and other radioactive constituents.5*
Because of the intrinsic hazard of many mining wastes, EPA relies primarily on the existing
authorities of the Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) to require removal and remediation at sites where mining wastes pose a hazard to human
health or the environment.55 Without this Superfund safety net, persons suffering environmental
damages from mine sites would have^o rely on common-law remedies such as trespass, nuisance, and
negligence.
This Superfund safety net was dealt a near fatal blow in the district court decision of Iron Mountain
where the mining industry argued that the Bevill Amendment expanded the exclusion to include
CERCLA liability.56 The Bevill Amendment exempts uranium mill tailings; from EPA's RCRA
49 Id.
50 Id.
51 Id.
52 Id.
53 See Hecla Mining Co. v. U.S., 909 F.2d 1371 (10th Cir. 1990). 21 Envtl. L. Rep. 20,256.
54 Mining Waste Sites on the NPL, Executive Summary, Preliminary Draft, 1992. Environmental
Protection Agency, Office of Solid Waste. (Document available from the aui:hor.)
55
42 U.S.C. §§ 9601-9626 (1988).
56 United States v. Iron Mountain Mines, Inc., 812 F. Supp. 1528, (E.D. Cal. 1992) reaffd,
recons. granted, summ. judgment denied. United States v. Iron Mountain Mines, 1993 U.S. Dist.
LEXIS 1665, (E.D. Cal. 1993).
55
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Mining Industry Profile: Uranium
Subtitle C regulations.57 The Iron Mountain court addressed whether Congress intended for the
Bevill exclusion to also protect mining wastes from CERCLA liability. The Iron Mountain court held
that "[t]he plain meaning of [CERCLA] § 101(14) suggests that only wastes not excluded by the
Bevill Amendment or by some other exclusion may be regulated by CERCLA."58 Iron Mountain
held that "even if mining wastes are covered by CERCLA, certain wastes are excluded from coverage
by reference to the Bevill Amendment in § 101(14)(C)."59 The Iron Mountain court specifically
rejected Eagle-Picher which held that an excluded mining waste may be subject to CERCLA liability
if its components otherwise qualify as a hazardous substance due to its toxicity or other
characteristics.60
In an unrelated case addressing the same issue, the Ninth Circuit in Louisiana-Pacific implicitly
overruled Iron Mountain with respect to CERCLA coverage of Bevill exempt mining waste.61
Louisiana-Pacific held that the Bevill exclusion only provides limited protection from CERCLA
liability and that hazardous constituents released from mining wastes can be regulated under
CERCLA.62
Summary of Major Court Actions Applicable to Uranium Mining
The four major cases interpreting UMTRCA are AMC I, AMCII, Quivira Mining, and AMC III.
AMCI addressed EPA's UMTRCA inactive site regulations under Title I and for the most part upheld
EPA's standards. AMC II upheld EPA's standards at active Title II sites. The decisions in AMC I
and AMC II affirm Congress's strong interest in the expeditious control of threats to human health and
the environment at uranium mill tailings disposal sites.63
Quivira Mining addressed and upheld NRC's implementing criteria. AMC III addressed and upheld
amendment to NRC's implementing criteria. The decisions in Quivira Mining and AMC III set forth
57 40 C.F.R. 261.4(b)(7) (1992).
58 Iron Mountain at 1540.
59 Iron Mountain at 1540.
60 Eagle-Picher Industries v. EPA, 759 F.2d 922 (D.C. Cir. 1985).
61 Louisiana-Pacific Corp. v. ASARCO, Inc., 6 F.3d 1332 (9th Cir. 1993), amended 13 F.3d
1378 (1994). It should be noted that Superfund is not the only safety net. When Iron Mountain held
that mining wastes were exempt from CERCLA, EPA issued a RCRA § 7003 imminent hazard order
to address the wastes under 42 U.S.C. § 6973. See Iron Mountain Cleanup Ordered Under RCRA
After Court Decides Mining Wastes Exempt, 24 Env't Rep. (BNA) 184 (May 28, 1993).
62 "It is clear from the plain language and structure of section 9601 that the specific exception for
slag in subsection (C) applies only to that subsection and that slag is regulated by CERCLA to the
extent that it falls under any other subsection of section 9601(14)." Louisiana-Pacific Corp. v.
ASARCO, Inc., 6 F.3d 1332, 1339 (9th Cir. 1993), amended 13 F.3d 1378 (1994).
63 58 Fed. Reg. 32,174, 32,179 (1993).
56
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Mining Industry Profile: Uranium
the scope of the cost benefit analysis used by EPA and NRC and concluded that it was proper for
NRC to rely on earlier cost benefit analysis developed by EPA.64
The practical effect of Louisiana-Pacific is that private uranium mining activities (non-UMTRCA
sites) are subject to Superfund liability, regardless of management practices and other environmental
exemptions. The net result is that private uranium mine owners and operators are subject to
Superfund liability just like most other industries. The Superfund safety net for uranium and other
radioactive mining wastes remains intact.
1.7.2.3 Department of Energy
Under the authority of the AEA, as amended, DOE has promulgated regulations for leasing public
lands controlled by DOE for uranium exploration and mining (10 CFR 760). (Some, but not all,
public lands with known uranium deposits were withdrawn by DOE from other land management
agencies; details surrounding the withdrawal of these lands were not obtained). Only citizens of the
U.S. or U.S. corporations are eligible lessees. DOE issues leases through competitive bidding. DOE
may, if it so chooses, require periodic submissions of plans for controlling environmental impacts.
The lessee will be required to conduct operations to minimize environmental effects, to comply with
all applicable State and Federal statutes and regulations, and to rehabilitate affected areas.
DOE is also responsible for remediating UMTRCA Title I sites to meet EPA standards, as described
above. Any remedy DOE selects to undertake pursuant to the UMTRCA must have NRC approval
prior to beginning remediation activities. As previously mentioned, DOE is responsible for the 24
Title II sites.
1.7.3 Clean Air Act
The three major components of the Clean Air Act program relevant to uranium extraction and
beneflciation operations are the National Ambient Air Quality Standards (MAAQS), which regulate six
criteria pollutants; the New Source Performance Standards, which regulate newly operating or new
expansions of major sources of air pollutants; and the National Emission Standards for Hazardous Air
Pollutants (NESHAPS), which regulate specific toxic pollutants emitted by specific industries.
Under the CAA (42 USC §7409, Section 109) EPA established national primary and secondary air
quality standards for six "criteria" pollutants. These are known as the National Ambient Air Quality
Standards (NAAQSs). The NAAQSs are maximum acceptable concentration limits for six air
pollutants, one of which is suspended paniculate matter of less than 10 microns in diameter. To
attain the air quality goals set by the CAA, States and local authorities have the responsibility of
ensuring their regions are in compliance with the NAAQSs. In addition, states may promulgate more
stringent ambient air quality standards. Although fugitive dust control is not an explicit requirement
of the Act, most States require fugitive dust suppression measures as part of their State
Implementation Plans (SIPs) to achieve the NAAQS for paniculate matter. Fugitive dust is common
at uranium mining operations: it arises from mine pits, overburden, mine rock dumps, ore, sub-ore,
and haul roads.
New Source Performance Standards (NSPSs), authorized under CAA §111, also have been
promulgated for paniculate emissions from all new or expanded uranium extraction activities (40 CFR
64
Id.
57
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Mining Industry Profile: Uranium
60, Subpart LL). However, uranium beneficiation activities and all underground processing facilities
are exempt from the NSPSs. Also, NSPS paniculate emission concentration standards only apply to
stack emissions. The NSPSs require operations to contain stack-emitted paniculate matter in excess
of 0.005 grams per dry standard cubic meter (dscm). In addition, stack emissions must not exhibit
greater than seven percent opacity, unless the stack emissions are discharged from an affected facility
using a wet scrubbing emission control device. Also, on or after 60 days following the achievement
of the maximum production rate (but no later than 180 days after initial startup), operations must limit
all fugitive dust emissions to 10 percent opacity.
Standards have been established for radionuclide emissions from various sources, including uranium
extraction and beneficiation activities, to the ambient air (40 CFR 61) under the authority contained in
the National Emissions Standards for Hazardous Air Pollutants (NESHAPs) portion of the CAA.
EPA regulations that apply to uranium extraction and beneficiation activities are outlined below
• Subpart B sets standards for active underground uranium mines. The standards in this
subpart apply to an owner or operator of an underground uranium mine that has mined,
will mine or is designed to mine over 100,000 tons of ore during the life of the mine, or
has or will have an annual ore production rate greater than 10,000 tons, unless it can be
demonstrated to EPA that the mine will not exceed 100,000 tons during the life of the
mine. The regulation sets an emission standard for radon from the mine not to exceed 10
mrem/y for any member of the public. Reporting requirements are also specified in the
regulation.
• Subpart H sets standards for facilities owned or operated by DOE, excluding inactive
facilities regulated by Titles I and II of UMTRCA, which emit any radionuclide other than
radon-222 and radon-220 into the air. Emissions of radionuclides from these facilities to
the ambient air shall not exceed those amounts which would cause any member of the
public to receive in any year an effective dose equivalent of 10 mrem/yr.
• Subpart I sets standards for NRC-licensed facilities and to facilities owned or operated by
any Federal agency other than the DOE (none were identified), except it does not apply to
any Title I UMTRCA facilities that have undergone remediation as provided for in 40 CFR
Part 192. Emission standards of radionuclides released from regulated facilities to the
ambient air shall not exceed amounts which would cause any member of the public to
receive in any year an effective dose equivalent of 3 mrem/yr.
• Subpart T sets standards for radon emissions from the disposal of uranium mill tailings.
The regulation applies to the owners and operators for all sites that are used for the
disposal of tailings that are listed in Title I of the Uranium Mill Tailings Control Act of
1978 or regulated under Title II of the same Act. Radon-222 emissions to the ambient air
from uranium mill tailings units that are no longer operational shall not exceed 20
pCi/m2/s.
• Subpart W sets emission standards for radon emissions from mill tailings at operational
mills. It applies to owners or operators of facilities licensed to manage uranium byproduct
materials from uranium mills and their associated tailings. Radon-222 emissions to the
ambient air from regulated facilities shall not exceed 20 pCi/m2-s. Tailings impoundments
built after Dec. 15, 1989 must be designed, constructed and operated to meet either phased
disposal in lined tailings impoundments that are not greater than 40 acres, or continuous
disposal of tailings such that tailings are dewatered and immediately disposed with no more
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Mining Industry Profile: Uranium
than 10 acres uncovered at any time. Tailings disposal must be in accordance with 40
CFR 192.32(3.).
EPA received several petitions for reconsideration of Subpart T because of concern that it overlapped
with UMTRCA requirements for the management of uranium byproduct materials (Subpart D of 40
CFR Part 192). As a result the EPA, NRC, and Agreement States signed a Memorandum of
Understanding (MOU) in October of 1991 that outlines the steps each will take to eliminate regulatory
redundancy and to ensure uranium mill tailings are closed as expeditiously as practicable. On June 8,
1993, EPA proposed amending UMTRCA regulations contained in 40 CFR Part 192, Subpart D (58
FR 32174). These proposed regulations include a requirement for installing a permanent radon
barrier designed to achieve the 20 pCi/m2-s radon emission standard, a compliance schedule for
meeting the 20 pCi/m2-s radon emission standard, and a monitoring requirement to ensure tailings
impoundment designs are effective at achieving the aforementioned standard. In the preamble to this
proposed rule, EPA stated its intentions to eventually rescind Subpart T of 40 CFR 61 (NESHAPs),
once it has been assured that the amended UMTRCA standards are as protective of public health with
an ample margin of safety, as are the NESHAPS rules. NRC and the Agreement Sates agreed to
amend the licenses of all sites whose milling operations have ceased and whose tailings piles remain
partially or totally uncovered. The amended license would require the mill operator to establish a
tailings closure plan.
1.7.4 Clean Water Act
Under section 402 of the CWA (33 USC §1342), all point-source discharges of pollutants to waters of
the United States must be permitted under the National Pollutant Discharge Elimination System
(NPDES). A point source is defined as any discrete conveyance, natural or man-made, including
pipes, ditches, and channels. NPDES permits are issued by EPA or delegated States.
Effluent limits imposed on an NPDES permittee are either technology-based or water-quality-based.
National technology-based effluent guideline limitations have been established for discharges from
uranium mines and mills under the Ore Mining and Dressing Point-Source Category (40 CFR Part
440, Subpart C). These regulations provide effluent limitations based upon best practicable control
technology (BPT) and best achievable technology (BAT) for uranium mills and open-pit and
underground uranium mines, including mines using in situ leach methods. Discharges from regulated
operations must meet best available technology/best practicable technology (BAT/BPT) standards for
zinc, arsenic, ammonia, dissolved radium 226, total radium 226, uranium, total suspended solids
(TSS), chemical oxygen demand (COD), and pH. The specific effluent standards for these
contaminants are shown in Table 1. EPA has also promulgated effluent guidelines for new uranium
mines and mills, known as New Source Performance Standards (NSPSs). New source performance
standards for mines are also listed in Table 1. New mills using acid leach, alkaline leach, or
combined acid and alkaline leach process for uranium extraction or mines and mill using in-situ leach
methods are not allowed to discharge process wastewater, unless annual precipitation exceeds annual
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Mining Industry Profile: Uranium
Table 1-1. Effluent Limitation Guidelines for Discharges from Mines and Mills in the
"Uranium, Radium, and Vanadium Ores Subcategory"
(milligrams per liter, except as noted)
Effluent characteristic
TSS
COD
As
Zn
Ra-226 (dissolved) (pCi/L)
Ra-226 (total) (pCi/L)
U
pH (s.u.)
Mine drainage
BPT limits
One-day
max
30.
200.
30-day
average
20.
100.
N/A
1.0
10.
30.
4.
0.5
3.
10.
2.
6.0 - 9.0
BAT limits
One-day
max
30-day
average
N/A
200
100
N/A
1.0
10.0
30.0
4.0
0.5
3.0
10.0
2.0
6.0 - 9.0
Mill discharges
BPT limits
One-day
max
30.
N/A
1.0
1.0
10.
30.
30-day
average
20.
500.
0.5
0.5
3.
10.
N/A
6.0 - 9.0
BAT limits
N/A
New Source Performance Standards
Effluent characteristic
TSS
COD
Zn
Ra-226 (dissolved) (pCi/L)
Ra-226 (total) (pCi/L)
U
pH (s.u.)
Mine drainage
One-day
mfryflniuTt
30.
200.
1.0
10.
30.
4.
30-day
average
20.
100.
0.5
3.
10.
2.
6.0 - 9.0
Mill discharges
No discharges of process wastewater allowed,
except: when net precipitation exceeds annual
evaporation, the difference may be discharged
subject to BPT limits for mine drainage.
N/A Not applicable (no standards promulgated)
NOTE: Limitations apply to discharges from open-pit or underground mines from which uranium, radium, and vanadium
ores are produced; and to mills using the acid leach, alkaline leach, or combined acid and alkaline leach process
for the extraction of uranium, radium, and vanadium. BPT and NSPS mine drainage limitations do not apply to in
situ operations; BAT mine drainage and all mill discharge limitations do apply to such facilities. In addition,
overflows from facilities designed/operated/maintained to contain or treat flows from the 10-year/24-hour storm
event may qualify for "storm exemption."
SOURCE: 40 CFR 440 Subpart C: 440.32 (BPT), 440.33 (BAT), 440.34 (NSPS)
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Mining Industry Profile: Uranium
evaporation.
The permit writers must also ensure that the NPDES permit will protect water quality. Permit writers
must also determine whether technology-based effluent limitations i.e., BPT, BAT, and/or NSPS) are
adequate to ensure that applicable water quality standards are met. Whete technology-based limits are
not sufficiently stringent, water-quality-based effluent limitations must be developed. As a result, a
NPDES permit may include technology-based effluent limitations for some pollutants and water-
quality-based effluent limitations for other pollutants. Individual states ate required to adopt water
quality criteria at least as stringent as Federal levels. The application of ihese criteria is based on the
designated use of a specific receiving water (drinking water supply, aquatic life, and/or recreational
use). Also, each State has been required to develop instream water quality standards to protect the
designated uses of receiving waters.
Contaminated storm water runoff from some mining operations has been documented as causing water
quality degradation. In the past, point source storm water discharges have received limited emphasis
under the NPDES program. However, EPA recently promulgated regulations (55 FR 47990;
November 16, 1990) that specifically address point-source discharges of storm water from industrial
facilities, including active and inactive/abandoned mine sites. These regulations require NPDES
permits for all point source discharges of contaminated storm water from mine sites. The
implementation strategy calls for discharges to be covered in individual (facility-specific) or general
(State or EPA Region-specific) NPDES permits. Some of the States authorized to implement the
NPDES program (e.g. Colorado, Wyoming) have developed general permits for storm water
discharges from mining facilities. For States not NPDES-authorized (e.g. Texas, Arizona), EPA is
developing a general permit. EPA is also developing a separate general permit for storm water
discharges from inactive/abandoned mines on Federal lands.
Some discharges from mine sites do not meet the definition of a "point source discharge." These
discharges are nonpoint source discharges. Under Section 319 of the CWA, States are required to
prepare nonpoint-source assessment reports and to develop programs to address nonpoint sources on a
watershed-by-watershed basis. Each State must report to EPA annually on program implementation
and resulting water quality improvements.
1.7.5 Safe Drinking Water Act
The Safe Drinking Water Act (SDWA) was enacted in 1974 and amended m 1986. It protects the
quality of drinking water by establishing standards for drinking water quality and treatment and
distribution systems, and by regulating the injection of waste and non-waste materials into disposal or
other injection wells. The SDWA's most direct impact on the uranium industry is through the
Underground Injection Control (UIC) Program, which aims to protect underground sources of
drinking water.
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Mining Industry Profile: Uranium
EPA is responsible for implementing (or overseeing the implementation of) the UIC program. EPA
regulations can be found in 40 CFR Parts 144-146. Upon EPA approval. States can be delegated the
responsibility for implementing all or part of the UIC program in their jurisdiction.
EPA's UIC regulations protect underground sources of drinking water (USDWs) by prohibiting the
direct injection or migration of foreign fluids into these aquifers. An underground source of drinking
water is defined as any aquifer or its portion that supplies a public water system or contains fewer
than 10,000 mg/1 total dissolved solids (IDS). An aquifer may be exempted from UIC regulation if
it is shown to be completely isolated with no possible future uses. In general. Federal regulations
prohibit any underground injection unless authorized by permit or by rule. In addition, no
owner/operator of a well may construct, operate, maintain, convert, plug, or abandon an injection
well in a manner which allows the movement of contaminated fluid into underground sources of
drinking water.
The program establishes requirements for five injection well categories. Regulations vary according
to the class of well. These categories are outlined below.
Class I: Injection wells for hazardous, industrial, non-hazardous, and municipal wastewater disposal
below the lower most formation, within 1/4 mile of the wellbore, containing an
underground source of groundwater.
Class II: Injection wells for fluids related to oil and gas production such as salt water disposal wells,
enhanced oil recovery wells and hydrocarbon storage wells.
Class III: Injection wells related to mineral extraction such as in situ production of uranium, only for
ore bodies which have not been conventionally mined.
Class FV: Disposal of radioactive or hazardous waste into or above a formation which contains an
underground source of drinking water within 1/4 mile. Section 3020(a) of RCRA prohibits
the construction and operation of Class IV wells.
Class V: Injection wells not included in the other classes. This includes solution mining of
conventional mines, such as slope leaching and low-level radioactive waste wells.
Classes I, III and V are potentially applicable to the uranium extraction and beneficiation industry.
The Federal requirements for these wells are summarized in the subsections that follow.
1.7.5.1 Class I Nonhazardous Wells
Area of Review and Corrective Action Plan
Applicants for permits to inject into Class I wells must identify the locations of all known wells within
the injection wells "area of review" that penetrate the injection zone. The "area of review" is the area
surrounding an injection well described in accordance with listed criteria, or in the case of an area
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permit, is the project area plus a circumscribing area (either one-quarter mile or calculated according
to criteria in the regulations).
For wells in the area of review that are improperly sealed, completed, or abandoned, the applicant
must also submit a corrective action plan. The purpose of this is to ensure that pre-existing wells do
not provide a conduit between the injection zone and underground sources of drinking water. An
approved plan must consist of steps or modifications as necessary to prevent movement of fluid into
underground sources of drinking water.
EPA (or the State) may require as a permit condition that injection pressure be limited so that
pressure in the injection zone does not exceed hydrostatic pressure at the site of any improperly
completed or abandoned well within the area of review. This limitation can be part of a compliance
schedule and may last until all other required corrective action has been taken.
The regulations list various factors upon which EPA (or the State) may base its decision that a
corrective action plan is inadequate. They include (1) the nature and volume of injected fluid; (2) the
nature of native fluids or byproducts of injection; (3) the potentially affected population; and (4)
abandonment procedures in effect at the time the well was abandoned. Each plan, for an existing
well, must include a compliance schedule requiring corrective action to be completed as soon as
possible. No new injection well may be used for injection until all required corrective action has
been taken.
Mechanical Integrity Testing
Submission of an application for EPA approval of a State UIC program must include a program
description, including an explanation of how the State will implement mechanical integrity
requirements required under the regulations.
A well must meet the following mechanical integrity requirements. First, there can be no significant
leak in the casing, tubing, or packer. One of the following methods must be used to determine that
there are no impermissible leaks: (1) monitoring the annulus pressure; (2) pressure test with liquid or
gas; or (3) a method authorized by the State or EPA other than the above, with the written approval
of the Administrator. Second, there may be no significant fluid movement into an underground
source of drinking water through vertical channels adjacent to the well bore. There must be no
significant fluid movement as determined by: (1) the results of a temperature or noise log; or (2) a
method authorized by the State with the written approval of the Administrator or by EPA.
When conducting and evaluating these tests, the owner or operator and the EPA (or the State) must
apply methods and standards generally acceptable in the industry. In reporting the results of integrity
testing to EPA (or the State), the owner or operator must include a description of the test(s) and the
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methods used. In making an evaluation, EPA (or the State) will review monitoring and other test data
submitted since the previous evaluation.
Technical Criteria and Standards
Among the technical criteria that apply to UIC programs to regulate Class I nonhazardous injection
wells are the following: (1).construction requirements, including that wells be sited so that they inject
into a formation beneath the lowermost formation containing an underground source of drinking water
within one quarter mile of the well bore, and that wells be cased and cemented to prevent movement
of fluids into underground sources of drinking water; (2) operating requirements, including that
injection between the outermost casing protective of underground sources of drinking water and the
well bore is prohibited; and (3) monitoring requirements, including that analysis be conducted of
injected fluids with sufficient frequency to yield representative data of their characteristics.
1.7.5.2 Class III Wells
Area of Review and Corrective Action Plan
Requirements with respect to the establishment of an area of review and the submission of a
corrective action plan described above under Class I nonhazardous wells also apply to Class III wells.
Additional requirements apply to Class III wells: when EPA (or the State) is considering the
appropriate corrective action, EPA (or the State) must consider the overall effect of the project on the
hydraulic gradient in potentially affected underground sources of drinking water. If the decision is
made that corrective action is not necessary, the required monitoring program must be designed to
verify the validity of such a determination.
Mechanical Integrity Testing
The same requirements that apply to Class I nonhazardous wells apply to Class III. However, there
is one difference with respect to methods that may be used to determine the absence of significant
fluid movement. Acceptable methods for such purposes include: (1) where the nature of the casing
precludes the use of the logging techniques prescribed in the regulations, cementing records may be
used to demonstrate the presdnce of adequate cement to prevent such migration; (2) where EPA (or
the State) elects to rely on cementing records to demonstrate the absence of significant fluid
movement, the monitoring program required by regulations shall be designed to verify such an
absence; and (3) as finalized in January 1992, EPA allows the use of the water-brine interface
mechanical integrity test for salt solution mining. (57 Federal Register 1109, January 10, 1992).
Technical Criteria and Standards
Technical criteria applicable to Class HI injection wells include (1) construction requirements,
including that wells must be cased and cemented to prevent migration of fluids into or between
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underground sources of drinking water and that casing and cementing used for newly drilled wells
must be designed to last the life of the well. Among the factors which must be considered in
determining casing and cementing requirements are depth to injection zon;, injection pressure, and
type and grade of cement; (2) operating requirements, including that except during well stimulation.
injection pressure at the wellhead must be calculated to assure that the pressure in the injection zone
during injection does not initiate new fractures or propagate existing ones; and (3) monitoring
requirements, including monitoring of the nature of injected fluids at time intervals sufficiently
frequent to yield data representative of their characteristics; and (4) reporting requirements, including
quarterly reporting to the EPA (or the State) on required monitoring and reporting on results of
mechanical integrity testing.
1.7.5.3 Class V Wells
In general, Federal regulations state that for Class V wells, injection is authorized by EPA until
additional requirements under future regulations are promulgated. This means that such injection
operations are authorized by rule, so no Federal permit is required. EPA has not yet promulgated
regulations governing this class of wells.
It should be noted that individual States with approved Class V UIC programs may have their own
technical requirements which apply to Class V wells in those States. (See discussion above on
General State UIC Program Requirements). Some States with approved UIC programs may require
permits, while other such States may authorize injection by rule.
A general provision of the UIC regulations that applies to Class V wells, is that no injection may be
conducted in a manner that allows the movement of contaminated fluid into underground sources of
drinking water.
Regulations require that within one year of the effective date of the UIC program in a particular State,
the owners and operators of Class V wells in the State notify the State of these wells and submit
required inventory information, including (1) facility name and location; (2) nature and type of
injection wells; (3) operating status of such wells.
For EPA-administered UIC programs only, additional information must be submitted by owners and
operators of certain types of Class V wells (in addition to other well classes). Among the types of
Class V wells for which additional data may be requested by EPA are brin<; return flow wells. Data
required to be submitted may include (1) a listing of all wells, including location of wells; (2) dates of
completion of such wells; (3) identification and depth of the formation into which each well is
injecting; (4) casing and cementing record, tubing size, and depth of packer; (5) average and
maximum injection pressure at the wellhead; and date of the last mechanical integrity test, if any.
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Under the UIC regulations, each State, in turn, is required to submit a report and recommendations to
EPA, within three years of the approval of the State UIC program, concerning Class V wells. The
report must contain data on (1) construction features of Class V wells in the State and the nature and
volume of injected fluids; (2) an assessment of the contamination potential of such'wells, using
hydrogeological data available to the State; (3) an assessment of available corrective alternatives and
their environmental and economic consequences; and recommendations for regulatory approaches and
remedial actions where appropriate.
1.7.6 Selected State Regulatory Requirements
This section addresses applicable laws, regulations and permits that apply to the uranium extraction
and beneficiation industry in Texas and Wyoming since these States contain the vast majority of
operating facilities. The section on State regulation is intended to provide an example of State
regulatory programs. It is not intended to be a comprehensive summary of regulatory programs in
these or other uranium mining States. Wyoming is authorized by EPA to administer NPDES and the
UIC program but is not authorized by the NRC for implementation of a AEA/UMTRCA program.
Texas is not an EPA-delegated State for NPDES permitting but has been delegated responsibility for
the UIC program under SDWA and is also authorized by NRC to implement the AEA/UMTRCA
program. Therefore, EPA writes NPDES discharge permits for uranium extraction and beneficiation
in Texas for discharges to surface waters and the NRC issues permits for uranium milling operations
in Wyoming.
1.7.6.1 Texas
Uranium extraction and beneficiation regulation in Texas is in a state of transition. Until recently, the
Texas Water Commission's UIC program had jurisdiction over injection wells, and the Texas
Department of Health's Bureau of Radiation Control handled all radiation and radioactivity at uranium
mines and mills, regardless of media (soil, air, or water). In March of 1992, the State legislature
passed Senate Bill 2, which gave jurisdiction of disposal of radioactive waste at in-situ mines to the
Texas Water Commission. The same legislation created a new agency, the Texas Natural Resources
Conservation Commission (NRCC) (to become effective on Sept 1, 1993). The entire Texas Air
Control Board, the entire Texas Water Commission (TWC), and parts of the Texas Department of
Health's Bureau of Radiation Control will be moved to the NRCC. Further, there are new bills
currently in the State legislature that could move all of the uranium extraction and beneficiation
regulatory functions, including licensing and inspections, to the NRCC.
Water Commission
The Texas Water Commission regulates some aspects of in situ uranium mining pursuant to the Texas
Water Quality Act, Chapters 26 and 27 of the Texas Water Code. The TWC does not address
surface water discharges associated with uranium extraction and beneficiation because Texas is not a
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NPDES-authonzed state. The Commission is the State authority administering the EPA-delegated
UIC program. Under the UIC program, the Commission has been responsible for the permitting of
non-radiological contaminants in injection fluids. Recently, however, the Commission has also
become responsible for administering NRC's authority over disposal of radioactive waste at in situ
mines, via injection wells. This authority stems from Texas becoming art NRC Agreement State in
the early 1960's. Previously, the Department of Health administered NRC's radiological contaminant
requirements at in situ mines, but the authority was transferred to the TWC in an effort to minimize
the number of permits needed by uranium solution mines (Kohler, 1993). A Memorandum of
Understanding (MOU) between the two agencies establishes responsibilities for each of the program
elements (Kohler, 1993). The Commission issues site-specific permits for solution mining, which
includes UIC and NRC requirements, and also issues subsequent production area authorizations under
the site-specific permit (TDWR, 1984). Some of the NRC and UIC (Class II wells) solution mining
permit requirements include:
• Restoration procedures such as plugging of wells and restoration of ground cover
• Liners for all wastewater ponds
• Leakage detection, repair procedures, and freeboard limits for all ponds
• Controlled access to the ponds to prevent entrance by wildlife and unauthorized persons
• Runoff and spill control measures
• Preventive maintenance such as inspection for ponds, pipelines, dikes, trenches, and
storage areas
• Disposal of all radioactive wastes pursuant to Department of Health requirements
• Disposal of non-radioactive solid and semi-solid wastes at an authorized waste disposal site
in accordance with the Texas Water Commission rules
• Use of non-ammonia leaching solution at production areas
• Sampling of monitoring wells every 3 months
• Proof of mechanical integrity of all injection wells
• Financial assurance, usually in the form of a bond, for proper plugging and abandonment
of wells, for any surface contaminant cleanup and restoration, including groundwater
remediation to levels that would allow unrestricted use
• Aquifer restoration to pre-mining conditions once mining has ceased.
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Department of Health
Texas is a NRC-Agreement State, and the Department of Health's Bureau of Radiation Control
(BRC), in conjunction with the TWC, is responsible for administering the NRC radiation regulatory
program for uranium extraction and beneficiation (see above). Texas has incorporated the NRC
regulations pertaining to uranium extraction and beneficiation into Texas' Regulations for Control of
Radiation (Haygood, 1993).
Previously, the BRC licensed (byproduct material) and conducted inspections at in situ mining
facilities. As noted above, both of these responsibilities, however, have been assumed by the TWC in
an effort to minimize the number of licenses (and permits) required from the industry (Haygood,
1993). The BRC, however, is still responsible for licensing uranium mills. Additionally, the BRC
also implements the NESHAPs provisions for radon at uranium in situ mines and uranium mills. The
BRC has no authority over uranium surface mines.
Railroad Commission (TRC)
The TRC regulates uranium surface mining, pursuant to the Texas Uranium Surface Mining and
Reclamation Act. It has jurisdiction over private lands, while the General Land Office has
jurisdiction over State lands (through a letter of agreement, the Commission actually regulates
operations on State lands under the General Land Office authority). As part of this responsibility, the
TRC issues bonds to ensure reclamation will be completed after mining has ceased (EPA, 1984). The
TRC also regulates the exploration phase of in-situ uranium mining. Once production of wells
begins, however, the Water Commission has regulatory jurisdiction. The TRC has promulgated its
regulations in Rules of the Surface Mining and Reclamation Division (EPA, 1984).
General Land Office
The General Land Office issues prospecting permits and mining leases on State lands. The General
Land Office has authority to regulate uranium mining on State lands, but does not exercise its
authority because it has turned it over to the Railroad Commission in a letter of agreement between
the two agencies. It requires a plan of operations as part of the mining lease application and may
specify certain reclamation requirements for obtaining a lease. Usually, however, the General Land
Office leases simply incorporate by reference the Railroad Commission's mining requirements (Farr,
1993).
Air Control Board
The Board is responsible for regulating non-radioactive air emissions, and must ensure that Texas
complies with National standards. The Board regulates fugitive dust from "non-agricultural
operations," which includes uranium extraction and beneficiation, and paniculate matter emitted from
stacks (Betrick Hameron, 1993). The Board's standards parallel those set by EPA (see above).
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Mining Industry Profile: Uranium
NESHAPs standards for radon emissions from uranium extraction and beneficiation are implemented
by the BRC, as noted above.
1.7.6.2 Wyoming
Most of the permits required by uranium mining and beneficiation operations in Wyoming must be
obtained through the Wyoming Department of Environmental Quality (WDEQ). The WDEQ consists
of four divisions: land quality, water quality, air quality and solid waste. Permits for impoundments
and reservoirs are issued by the State Engineer's Office (SEO); the SEO also handles issues involving
water rights. Wyoming is not a NRC delegated state, so, uranium milling and in situ operators must
apply to the NRC for a Source Materials License.
Department of Environmental Quality
Land Quality Division (LQD). The LQD is the lead agency in permitting mining operations and is
the sole authority for issuing mining permits. The LQD and WQD jointly issue Groundwater
Pollution Control permits for in situ operations. Groundwater monitoring data are submitted to and
reviewed by the LQD. The LQD is responsible for bonding provisions and annual inspections. In
addition, the LQD distributes guidelines addressing numerous permit-relafcd topics including In Situ
Mining, Hydrology, Soils and Overburden, and Vegetation. Land Quality Division Mining Permit
Requirements include:
• Baseline Groundwater Quality Survey - for the permit area and sach mining unit (UCLs
are determined at this time)
• Hydrogeologic Characterization
• Surface Water Baseline (quality and quantity)
• Geological Assessment .
• Detailed Mineral Extraction and Reclamation Plan.
• Bonding (for the cost of reclaiming affected land or ground water disturbed by mining)
• Vegetation survey (including Threatened and Endangered Species;)
• Soils Assessment
• Wildlife Inventory.
Water Quality Division fWOD). Since Wyoming has been delegated NPDES and UIC programs, the
WQD issues all permits for surface water discharges (i.e., NPDES) and underground injection
(injection/production wells and disposal wells). The operation of injection and production wells are
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Mining Industry Profile: Uranium
also covered under the LQD/WQD Groundwater Pollution Control permits. Wastewater Land
Application Facility permits are required by in situ operators who dispose of excess process water
through land application.
State Engineer's Office
The SEO requires that all dams and impounding structures be certified by a professional engineer.
The office is also the lead agency for impacts on water rights.
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From the Extraction and Beneficiation of Metallic Ores, Phosphate Rock, Asbestos, Overburden
from Uranium Mining, and Oil Shale. U.S. Government Printing Office, Washington, DC.
U.S. Nuclear Regulatory Commission, Division of Waste Management. 1986. An Analysis of
Excursions at Selected In Situ Uranium Mines in Wyoming and Texas. Prepared by W.P Staub,
N.E. Hinkle, R.E. Williams, F. Anastasi, J. Osiensky and D. Rogness.
Wallace, A.R. 1986. Geology and origin of the Schwartzwalder uranium deposit, Front Range,
Colorado, USA. In: Vein Type Uranium Deposits, Report of the Working Group on Uranium
Geology Organized by the International Atomic Energy Agency. IAEA-TECDOC 361. IAEA,
Vienna, Austria, pp. 159-168.
Wyoming Department of Environmental Quality, Land Quality Division. 1991. In Situ Mining State
Decision Document for Everest Minerals Highland Uranium, WDEQ/LQD Permit No. 603-A2.
Wyoming Department of Environmental Quality, Land Quality Division. 1990. Guideline No. 4, In
Situ Mining.
Wyoming Department of Environmental Quality, Land Quality Division. 1989. Non-coal Rules and
Regulations.
Yan, T.Y. 1990. Uranium precipitation from eluate using hydrogen peroxide. American Institute of
Mining and Metallurgical Engineers, Minerals & Metallurgical Processing 288:222-224.
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APPENDIX A
NPL SUMMARIES RELATED TO URANIUM EXTRACTION AND BENEFICIATION
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Appendix A
NPL Summaries Related to Uranium Extraction and Beneficiation
This Appendix includes summaries of Superfund National Priorities List (NPL) sites related to
extraction and beneficiation of uranium. The original summaries were prepared by EPA in 1991.
Excerpts from these summaries are included in this profile as case study examples of select mining
operations. The summaries provide a brief description of the operation, but focus on site-specific
environmental effects and, in several cases, provide a brief summary of EPA actions at the site. The
NPL examples illustrate some of the problems associated with uranium mining. As stated in the
introduction, uranium processing wastes are not addressed in this profile. Although there are uranium
processing-related sites on the NPL, they have not been discusses in this Appendix. At some sites
discussed, however, both tailings and processing wastes contributed to the environmental hazards that
resulted in their listing on the NPL.
Homestake Mill; Grants, New Mexico
Operating History
The Homestake Mill Superfund Site is located in Cibola County, New Mexico, approximately 5.5
miles north of Milan, New Mexico. The site consists of an uranium processing mill and two tailings
embankments at an elevation of approximately 6,600 feet. The mill began operating in 1958, and was
originally licensed by the Atomic Energy Commission. The Mill has a nominal design capacity of
3,400 tons per day (tpd). The site was placed on the NPL in September 1983. In June 1990 the Mill
stopped operating and went on "standby status."
When operating, the Mill employed an alkaline leach-caustic precipitation process for extracting and
concentrating uranium oxide (yellow cake) from ores that historically averaged from 0.05 to 0.30
percent U3Og, to produce yellowcake. Tailings from the process are composed of uranium-depleted
fine and coarse sand and slimes.
Two separate embankments have been used to dispose of tailings generated at the mill. The most
recently used embankment consists of two impoundments, and covers approximately 175 acres with
tailings that total 17 million cubic yards (21 million tons) and measure 90 to 100 feet high. The
tailing embankment is constructed of coarse tailing material, and at least 60 acres were covered by
water. The second embankment, which has not been in use since 1962, covers approximately 45
acres, measures 25 feet high, and contains 1.225 million tons of tailings. More than 95 percent of
the top of this embankment is covered with at least 6 inches of soil.
Tailings were slurried from the Mill to the embankments. The tailings were deposited on (and
within) the embankment by means of wet cyclones, which separate the material into coarse and fine
splits. The tailing piles have been stabilized with solid materials such as erosion control blankets and
used tires, wetting the piles with water, and chemical-stabilization agents that form a crust on the
surface to reduce water and wind erosion.
An injection and collection effort has resulted in a decrease in the groundwater contaminant plume,
which no longer extends past the facility boundary.
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Environmental Damages and Risks
The EPA evaluated risks to public health from exposure to the levels of radon found during the study.
Lung cancer lifetime risks per year for the 17 residents of the 8 houses [with more than 4 pCi/1
average annual indoor radon concentrations] range from 0.000031 to 0.000!>9 and center around 1 in
10,000 per year of residency for all age groups. The evaluation indicates that this is not considered a
significant risk, as the models used are very conservative. Further, the mill site is not believed to be
the main source of the radon contamination.
Lincoln Park Site; Canon City, Colorado
Operating History
Uranium milling began at the Cotter site in 1958. The first mill operated until 1979 using an alkali
process. An acid leach mill process began in 1979, but has been inactive si.ice 1986. The site covers
approximately 1.4 square miles in south central Colorado and consists of two inactive mills, a
partially reclaimed tailings pond disposal area, and an inactive tailings pond disposal area.
During the milling process, molybdenum and vanadium were recovered as by-products during
uranium concentrate production. During the period of alkali milling (prior to 1979), 10 ponds were
used for storage of process liquid and fresh water, for the disposal of tailings, and for storage of fresh
water. These ponds are unlined except for Pond 2 (lined in 1972); Pond 3 (lined in 1981); and Pond
10 (lined in 1976).
In December 1979, when the acid milling process began, a double-lined impoundment was installed
with drains above the synthetic membrane and below the clay layer and synthetic membrane. Tailings
from this acid leach process and water collected from ground-water interceptors are stored in this
impoundment. It consists of two sections: (1) a 91-acre primary impoundment for the storage of acid
leach mill wastes; and (2) a 44-acre secondary impoundment. During the period between April 1981
to August 1983, the contents of Ponds 1, 2, 4, 5, 6, and 8 (2.2 million cubic yards of tailings) were
moved to a double-lined secondary impoundment. Ponds 9 and 10 were removed in 1978 during
construction of the secondary impoundment.
Reagents used in the milling process included sulfuric acid, ammonia, ammonium sulfate, kerosene,
tertiary amines, sodium and calcium salts, potassium permanganate, zinc sulFate, and organic
flocculents.
The Mill occasionally processed custom ores such as waste raffinate from other mills and precipitates
or slags from other processes. In one instance, Poly chlorinated Biphenyl (PCB)-contaminated ore was
processed, which contaminated some of the plant areas. Trichloroethylene was used to extract the
PCBs from the contaminated soils. This issue was being investigated by EPA at the time the
Remedial Investigation was prepared in 1986.
A catalyst plant on the Mill site was operated briefly in 1978 and 1979 to recover metal values from
spent catalyst material. Spent sulfuric acid catalyst material is currently stockpiled north of the old
Mill.
Sources of contamination include the uranium ore stockpile, tailings, and raffinate; contaminated soils
and groundwater; leaks from the old tailings ponds; and suspected leaks from the new impoundment
area. Contaminants include radium, nickel, molybdenum, cobalt, copper, arsenic, zinc, lead, and
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cadmium. The Cotter site is located south and almost adjacent to the semirural area of Lincoln Park
and 3.5 miles south of Canon City. The site is located in a topographic bowl known as "Wolf Park
Basin." Offsite ground-water contamination from the Cotter site was first noted in the Lincoln Park
area in 1968. Prior to a 1988 State-ordered clean-up, a number of residences used water from wells
on their property, either in addition to their Canon City tap water or as their sole supply. Homes in
the impacted area are presently supplied with Canon City water. Most land around the Mill is used
for grazing livestock and wildlife habitat.
Environmental Damages and Risks
The AEC was the regulatory agency responsible for oversight of the facility from 1958 to 1968.
Between 1959 and 1966, the site was cited 18 times for failing to track radioactive releases. The
State of Colorado Department of Health assumed regulatory oversight in 1968 and cited Cotter
Corporation 82 times for various violations under the Nuclear Regulatory Commission regulatory
process between 1968 and 1984. Among the state citations were exceedance of "As Low As
Reasonably Achievable" paniculate emissions, discharge and releases from tailings discharge pipes,
and poor recordkeeping on control of off-site surface-water contamination.
Contaminated groundwater at the site is transported downgradient into the Lincoln Park area.
Ground-water contamination was first noted in Lincoln Park in 1968. Concentrations of molybdenum
in Lincoln Park groundwater were in the range of 24 to 60 mg/1 (compared to a background level of
about 0.005 mg/1). These levels were described as injurious to cattle and unsuitable for irrigation of
crops used for cattle feed. A contaminant plume of uranium and molybdenum extends from the
Cotter site (in the shallow pathway along the Sand Creek drainage) into Lincoln Park and eventually
to the Arkansas River. Concentrations of molybdenum and uranium at the Mill site from 1981 to
1984 ranged up to 231 and 116 mg/1, respectively, in Lincoln Park. Concentrations in Lincoln Park
ranged up to 0.92 and 13.2 mg/1. Maximum concentrations in Lincoln Park of lead and selenium, as
well as gross alpha and beta, exceeded Maximum Contaminant Levels for drinking water.
Wind transport of contaminants has been observed since 1958. Emissions of radionuclides and
hazardous metals have been measured through air and soil sampling. Offsite soil concentrations of
metals are at (or above) a level of concern for agriculture use, cattle grazing, and wildlife. In
particular, soil concentrations were above critical values for molybdenum, cobalt, nickel, arsenic,
copper, zinc, and cadmium. In general, it was found that contamination decreased with distance from
the Cotter site. Contaminated offsite soils are, in turn, entrained in surface flow, and contaminants
are transported in the intermittent streams to the Arkansas River.
Offsite vegetation samples were also shown to be contaminated, with levels exceeding levels toxic to
plants and/or animals of molybdenum, zinc, and cadmium.
Uravan Uranium Mill; Uravan, Colorado
Site Overview
The Uravan Uranium mill complex is located approximately 90 miles southwest of Grand Junction
along State Highway 141 in Montrose County, Colorado. The mill was built at Club Mesa, west of
the San Miguel River canyon.
Standard Chemical Company began operating the Uravan Mill facility in 1915 to recover uranium,
vanadium, and radium from mined ores. Ore was received at the Uravan Mill from approximately 60
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different underground mines in the Uravan mineral belt, most of which were within 35 to 40 miles of
the mill. Union Carbide bought the facility from Standard Chemical through the U.S. Vanadium
Company in 1936 and continued to process uranium and radium at the site. While in operation, the
mill processed approximately 1,000 tons of ore per day.
Stockpiled ore was crushed, ground, and then beneficiated onsite. Benefication at the mill included
hot, strong acid leaching in a two-stage circuit followed by the recovery of pregnant solutions in
thickeners. Uranium was recovered from the pregnant solution and separated from vanadium by
column ion exchange, with the final yellowcake product precipitated with ammonia. The uranium
yellowcake and crude vanadium precipitate was then further processed at another Union Carbide
facility in Rifle, Colorado.
Plant tailings from the thickener circuit were pumped into tailings piles which, by late 1984, covered
over 80 acres and contained approximately 10 million tons of tailings. The tailings have a low pH
and are contaminated with both metals and radionuclides.
Raffinate, a liquid or crystallized waste of primarily hydrated ammonium sulphate from the milling
and extraction process, contains ammonium-aluminum salts, dissolved ore elements, and spent
processing reagent. These wastes contain hydrated ammonium sulfate, uranium, vanadium, iron,
sodium, radium, calcium, silver, silicon, potassium, sulfate, carbon, mercury, lead, molybdenum,
manganese, zinc, cobalt, copper, chromium, and nickel. The liquid form of this waste was stored in
evaporating ponds, while the crystallized waste was stored in onsite repositories. The river ponds
along the San Miguel River are below the level of the potential maximum flood. Analyses of liquid
and solid components of Uravan wastes show high levels of many metals.
The principal waste management areas onsite and in associated areas are:
• Atkinson Creek Crystal Disposal Area - Unlined storage pit along the San Miguel River
containing 200,000 cubic yards of raffmate crystals.
• Club Ranch Ponds - Six unlined ponds covering 32 acres located along the San Miguel
River that contain 30 million gallons of liquid raffmate and 560,000 cubic yards of
raffinate crystals.
• River Ponds - Seven unlined ponds constructed in old tailings piles containing 200,000
cubic yards of neutralized mill sludge and contaminated soils. The seven ponds are located
along both sides of the San Miguel River. These were used as holding areas for liquid
waste collected in the mill area before they were discharged into the San Miguel River.
• Tailings Piles - About 10 million tons of mill tailings contained in three piles (at two sites)
that are located on the Club Mesa, 400 feet above and west of the mill site.
• Club Mesa Area - Disposal area on Club Mesa consisting of two clay-lined sludge storage
areas, storage ponds, raffinate spray evaporation area, and associated contaminated soils;
contains 250,000 cubic yards of raffinate crystals, 150,000 cubic yards of neutralized
sludge, 40,000 cubic yards of contaminated pond material, and 44,000 cubic yards of
contaminated soil.
• Plant Areas - Two plant locations with surficial contamination including containment
structures, ore stockpile area, equipment and auxiliary wastes, and heap leach sites
containing 15,000 tons of ore.
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• Town and Adjacent Areas - Several small communities and three larger population centers
located along the San Miguel River are within 50 miles of the site. Old tailings and
contaminated soil have been found in these areas.
Mining, milling, and waste disposal activities have resulted in:
• Wind and surface-water dispersal of the tailings materials and the uncontrolled release of
radon from the Tailings Piles
• Seepage of contaminated liquids into soils and groundwater from several areas in the mill
complex and waste disposal areas
• Concentrations of large quantities of wastes in locations that pose a risk to public health
and the environment, based on considerations of the potential for release of hazardous
materials to the environment.
Environmental Damages And Risks
Initial interest in the site was prompted by the State of Colorado's belief that contamination (resulting
from poor waste management practices at the Uravan facility) was impacting the State's natural
resources.
Several small communities (Nucla, Naturita, Vancorum, Redvale, Norwood, Placerville, Saw Pit,
Paradox, Bedrock, Gateway, Olathe, Whitewater, Glade Park, Monticello, and Moab) and three
larger population centers (Grand Junction, Delta, and Montrose) are within 50 miles of the site. The
total area population is thought to be around 3,000 people, down from 5,500 in 1960. (According to
EPA, residents of Uravan were advised to move away in 1985 due to the high levels of radioactivity
measured in the area. By 1986, only 50 permanent residents remained. In 1988, after all permanent
residents had relocated, all company homes and buildings in Uravan were demolished.) No drinking
water is drawn from the San Miguel River downstream of the facility site, although water is drawn to
irrigate local hay fields.
Without remediation, the potential risk to human health as a result of the site contamination is thought
to be moderate. This is because of the modest size of the population actually residing in the risk
area. It was concluded that even if the facility experienced a large release of contaminants into the
environment, based on present population, very few people would be affected. Radiological and
nonradiological contaminants in the tailings area represent the source or origin of the greatest
potential human health hazard associated with the Uravan Mill.
Potential radiological environmental hazards arise from the radioactivity released during the milling of
natural uranium and are primarily associated with the natural decay of uranium 238, the parent
isotope, and its radioactive daughters present in the ore. In the tailings pile specifically, the decay
and ingrowth of the short-lived radon gas and its daughters represent major contributions to the
potential radiological hazard associated with the Uravan Mill. As of 1986, radiation sources
associated with the tailings piles constituted over 50 percent of the total airborne radioactivity released
from the Uravan uranium milling operation. This was expected to increase to 90 percent of the total
airborne radioactivity released from the mill, which permanently closed in 1991. The longer the
operational or active open surface lifetime, the greater the potential hazard of the tailings pile
radiation source due to potential releases. However, according to EPA, nearly all tailings piles have
been capped, and are not as large a source of airborne radioactivity.
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Both forage and vegetables in the site area are consumed by wildlife and livestock. These
contaminants will bioaccumulate as a result of consumption by either animals or humans that are
primary or secondary consumers. The high dispersion of contaminants in the area is attributed to
wind transport of contaminated particles.
Monticello Mill Site; San Juan County, Utah
Operating History
The Monticello Mill Tailings site is an abandoned uranium/vanadium mill occupying 78 acres in, and
adjacent to, the City of Monticello, San Juan County, Utah. The tailings and residual ore remaining
at the site have contaminated soils, groundwater, and surface water in Montezuma Creek, which flows
through the Mill site. An additional 300 acres of peripheral properties (properties adjacent to the Mill
site and a 3.3-mile reach of Montezuma Creek between the Town of Monticello and Vega Creek)
have been contaminated by airborne particles from tailings and water-transported tailings and ore
from leftover piles.
The Monticello Mill site began operation as a vanadium ore-buying station m the 1940's. As ore
production increased, a vanadium mill was constructed with government funding. The Mill began
vanadium production in 1942 and uranium-vanadium sludge production in 1943 for the Manhattan
Engineer District. The mill was closed in February 1944; it was reopened :in 1945 and produced
uranium-vanadium sludge until 1946. A salt-roast process was used to convert vanadium minerals to
soluble form. After pyrite was added to react with some of the calcium (in the excess lime in the ore)
to form calcium sulfate, the hot ore was quenched in sodium carbonate to dissolve most vanadium and
precipitate out calcium carbonate. Remaining sands, after successive washings, were transferred to
tailings ponds. The addition of sulfuric acid to the "pregnant liquor" (i.e, the vanadium-bearing
solution) induced the precipitation of vanadium pentoxide. The precipitate was washed to remove
sodium chloride and sodium sulfate, and the wash water was discharged to ihe creek.
In 1948, the Atomic Energy Commission (AEC) bought the Monticello Mill site from the War Assets
Administration and operated a uranium mill at the site until January 1960. Numerous uranium
milling processes were used during this period to accommodate the wide variety of ore types received
at the mill. Up to 1955, processes included raw ore carbonate leach, low-temperature roast/hot
carbonate leach, and salt roast/hot carbonate leach; acid leach-resin-in-pulp (RIP) and raw ore
carbonate leach from 1955 to 1958; and a carbonate pressure leach RIP process from August 1958
until closure of the mill in 1960. The ore-buying station remained open until March 31, 1962. Other
than parts of the land transferred to the U.S. Bureau of Land Management, since 1949 the site has
remained under the control of the AEC and its successor agencies [first the U.S. Energy Research and
Development Administration and, more recently, the U.S. Department of Energy (DOE)].
Four tailings impoundments were constructed at the Monticello Mill site. Two tailings
impoundments, the Vanadium Pile and the Carbonate Pile, received waste material prior to the 1955
installation of the acid leach RIP plant. The Carbonate Pile received tailing;; from the AEC salt
roast/hot carbonate leach milling process. It is not known which of the several milling processes in
use prior to acid leach-RIP produced the tailings in the Vanadium Pile. The Vanadium Pile and the
Carbonate Pile may have been used simultaneously. The Acid Tailings Pile received waste in 1955
and 1956 from the operation of both the acid leach-RIP and carbonate-leach plants. Tailings from the
acid leach process were combined with carbonate plant tailings and calcium hydroxide for
neutralization and then pumped to the Acid Pile (where a portion of pond overflow was recycled •
through the leach circuit). The remaining overflow was discharged to Montezuma Creek. To reduce
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discharges to Montezuma Creek, the Acid Pile was constructed with a 6-inch liner of compacted
bentonite to prevent seepage; tailings-pond effluent was partially recycled. A fourth tailings
impoundment, referred to as the East Pile, was constructed to increase capacity. It received tailings
from 1956 to 1960.
During the Mill's period of operation, the tailings impoundments were moist. However, within a
year of shutdown, the surfaces dried out and tailings sand began to migrate as sand dunes. In
addition, water erosion "became a problem."
AEC began stabilizing the piles in the summer of 1961 by grading, adding 8 to 12 inches of fill,
adding topsoil, and planting native grasses. Concurrent with the tailings-pile stabilization, the Mill
facilities were dismantled. Equipment was sold, burned, or buried onsite in trenches excavated near
the Carbonate Pile (and covered with tailings).
During the summer of 1965, contaminated surface soil was removed from peripheral properties
previously used for ore storage. This soil may have been used as fill material to partially bury the
mill foundations. Following a radiation survey of the South Stockpile Area and Ore-buying Station in
1972, contaminated soil was removed from these areas in May 1974 and August 1975. Nearly
15,000 cubic yards of contaminated soil, which was placed on top of the East Pile, was graded,
contoured, and reseeded. Mill foundations were demolished and bulldozed into adjacent pits.
The Monticello Mill site was accepted into the Surplus Facilities Management Program in 1980 and
the Monticello Remedial Action Project was established to restore the government-owned Mill site to
safe levels of radioactivity; to dispose of (or contain) the tailings in an environmentally safe manner;
and to perform remedial actions at offsite (vicinity) properties that had been contaminated by
radioactive material from mill operations. Site characterization activities commenced in 1981.
According to EPA, approximately 1.8 million cubic yards of tailings and contaminated soil are
located in the tailings-impoundment area on the east side of the mill. An additional 100,000 cubic
yards of contaminated materials have been identified in the Mill area. The tailings and contaminated
soils contain elevated levels of both radioactive and nonradioactive contaminants of concern. These
constituents are products of the uranium 238-decay cycle (including radium 226) arsenic, cadmium,
chromium, copper, lead, mercury, molybdenum, nickel, selenium, vanadium, and zinc.
As of 1990, the population within 1.5 miles of the site was estimated at 1,900. The population is
concentrated north and west of the Monticello Mill site. The Mill site is located in a controlled land
zoning district that permits a mix of agricultural, residential, commercial, and industrial use. The
average annual precipitation in the Monticello area is 18.3 inches. Prevailing annual winds are
generally from the south, west-southwest, and northwest.
Environmental Damages and Risks
Radiological Contamination
The Public Health Assessment identified radon gas and gamma radiation as the major radiologic
contaminants of concern. Adverse health effects arise from the inhalation of radon gas (a decay
product of the radium 226 found in the tailings), as the lungs are exposed to the full radiation dose of
the radon daughters. In contrast, gamma radiation creates adverse health effects as a result of full-
body exposure.
Five potential exposure pathways were identified and considered for quantitative analysis:
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(1) inhalation and ingestion of airborne radioactive particulates; (2) ingestion of contaminated foods
(plant and animal) produced in areas contaminated by wind-blown tailings; (3) ingestion of surface
water contaminated by tailings; (4) inhalation of radon and radon daughters; and (5) direct exposure
to gamma radiation emitted from the tailings.
The first two pathways were concluded to present insignificant exposure to humans since radiologic
analysis of air particulate samples typically yielded levels below detection. The third pathway
(ingestion of contaminated surface water) was not considered a "probable pathway" because: (1)
elevated radium concentrations have not yet been detected in Montezuma Creek; and (2) although
elevated concentrations of uranium have been detected in the Creek, the uranium dose rate is low at
low concentrations and it has a very long half-life (because of this, uranium exposure was examined
under nonradiological risks).
Two pathways remained: (1) inhalation of radon and radon daughters; and (2) direct exposure to
gamma radiation emitted from the tailings. The cancer risk associated with inhalation of radon and
radon daughters from the Mill site and peripheral properties was estimated to be 0.0038 excess annual
cancer incidences to the Monticello population. Cancer risks from whole-body gama radiation
exposure were an estimated 0.02 excess annual cancer incidences for the Monticello population. (The
Radiological Risk Assessment was performed on a population basis prior to later EPA guidance on
performing radiological risk assessments on an individual basis).
Nonradiological Contamination
The following nonradioactive elements were selected as "highest risk" or indicator contaminants at the
Mill site or peripheral properties: arsenic, copper, lead, molybdenum, selenium, uranium, vanadium,
and zinc. Noncarcinogenic health effects can arise from acute and chronic exposures to all eight
elements; only arsenic was considered to be a human carcinogen.
Four potential exposure pathways were identified based on the population and activity patterns in the
vicinity of the Mill site: (1) resuspended dust inhalation; (2) soil ingestion; (3) vegetable ingestion;
and (4) beef ingestion. The first pathway was excluded from further quantitative analysis because
particulate concentrations were at background levels or below, and the Remedial Investigation
determined that lead concentrations were well below NAAQS. The second pathway was also
excluded because current and expected future access to the site (it is currently fenced) is, and will be,
very limited. The vegetable and animal ingestion pathways were retained for quantitative analysis,
since the pathways are considered to be indirect exposure routes resulting from contaminated surface
water used to irrigate fields and water livestock.
A human "dose" (intake) was calculated for each indicator metal and pathway (vegetable and beef
ingestion) for both adults and children based on the average and maximum concentrations of indicator
metals found in soils. Each "dose" was compared to an EPA- developed reference dose for chronic
(long-term) exposure to each metal. This comparison revealed that no reference doses were exceeded
based on average metal concentrations; and therefore, the calculated doses ars not likely to be
associated with health risks. However, when maximum metal concentrations were used, uranium,
copper (including the vegetable pathway), and zinc (the beef pathway, including or excluding the
vegetable pathway) "doses" for children were exceeded. It was concluded, however, that it was
unlikely that individuals would receive chronic exposure to these maximum concentrations (because
the site is uninhabited and because of past land-use patterns). Thus, there was "no apparent health
risk".
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Arsenic is the only Mill site contaminant of concern that was considered a carcinogen by EPA.
Cancer risk due to ingested arsenic (via the vegetable pathway) was calculated using soil
concentrations. At maximum soil concentrations, the excess lifetime cancer risk is 2.7 x 10~5; and it
is 7.0 x 10"6 for average soil concentrations. Calculated cancer risk due to ingested arsenic (via the
beef pathway) was calculated using soil concentrations. At maximum soil concentrations, the cancer
risk is 2.0 x 10"5; and it is 2.0 x 10"6 for average soil concentrations. It was concluded that "arsenic
may pose a public health impact under the existing conditions at the site".
United Nuclear Corporation, Churchrock Site; Gallup, New Mexico
Operating History
The United Nuclear Corporation (UNC) Churchrock Site is an inactive uranium mill and tailings-
disposal site located in an isolated area of McKinley County, 15 miles northeast of Gallup, New
Mexico. The Mill was operational from 1977 to 1982. The Mill, designed to process 4,000 tons of
ore per day, used the conventional acid-leach solvent-extraction method to extract uranium. The ore
processed at the site (average ore grade 0.12 percent uranium oxide) came from UNC's Northeast
Churchrock and Old Churchrock mines as well as the nearby Kerr-McGee Quivera mine. The waste
tailings were pumped to a 100-acre tailings-disposal area. According to radioactive materials license
records, between 3.4 and 3.6 million tons of acidic tailings were disposed of at the site.
UNC's tailings-disposal area is located directly east of Pipeline Canyon. The tailings-disposal area
was subdivided by cross-dikes into cells identified as the South Cell, Central Cell, and North Cell
areas. Two soil-borrow pits are in the Central Cell area. In July 1979, the dam on the South Cell
breached, releasing approximately 93 million gallons of tailings and pond water to the Rio Puerco
River. The dam was repaired and clean-up actions were taken.
In October 1979, the New Mexico Environmental Improvement Division (NMEID) ordered UNC to
implement a discharge plan to control contaminated tailings seepage which was responsible for
ground-water contamination. Ground-water pumping and evaporation was initiated in 1981. From
1979 to 1982, UNC neutralized tailings with ammonia and/or lime. In May 1982, UNC announced
that it was going to temporarily close the Churchrock Uranium Mill due to depressed uranium market
conditions. The market did not recover, and UNC closed the facility. In 1987, UNC submitted a
closure plan to NRC to decommission the Mill. In 1983, EPA designated the Churchrock site an
NPL Site'and initiated a Remedial Investigation effort.
Environmental Damages And Risks
Arsenic, cadmium, lead, molybdenum, cobalt, manganese, chromium, and radionuclides (including
uranium and thorium) are the constituents of concern at the site. Although no people reside within
the site boundary, adjacent land includes the Navajo Indian Reservation to the north and land to the
east and south held in trust for the Navajo Tribe and administered by the Bureau of Indian Affairs.
Ten wells are located in slightly over a 3-mile radius of the site; the closest is 12,000 feet northeast of
the site. Four of these wells are operational, and are used for both livestock and domestic purposes.
Land use is primarily grazing for sheep, cattle, and horses. Contaminants in the Alluvial Aquifer
and/or deeper aquifers at concentrations exceeding clean-up standards include aluminum, arsenic,
cadmium, cobalt, manganese, molybdenum, nickel, selenium, nitrate, Total Dissolved Solids (TDS),
radium 226 and radium 228, and gross alpha.
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A Risk Assessment, based on ingestion of groundwater contaminated at 1985 levels, estimated excess
lifetime cancer risks for arsenic and radionuclides (the only carcinogens among the contaminants).
The excess lifetime cancer risk from arsenic ingestion was estimated as 1 x 10"1 (based on a maximum
arsenic concentration) to 1.2 x 10'3 (average concentrations).
For radionuclides, the excess cancer risks was estimated to be 1.8 x 10"' to 6.5 x 10~5. In addition,
estimated daily intakes of cadmium, manganese, and nickel were estimated 10 exceed health-based
standards for noncarcinogens. These estimates were all based on a "future-use scenario," in which it
was assumed that wells would be constructed for domestic use in each of the clean-up target areas.
However, EPA has found no current exposure from ground-water ingestion from currently operating
domestic and livestock wells within 4 miles of the site.
A-10
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Mining Industry Profile: Uranium
APPENDIX B
ACRONYM LIST
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Mining Industry Profile: Uranium
Acronym List
AMD acid mine drainage
BAT/BPJ best available technology/best professional judgment
BLM Bureau of Land Management
BMP best management practice
BPJ best professional judgment
CAA Clean Air Act
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CIP carbon-in-pulp
CWA Clean Water Act
FLPMA Federal Land Policy and Management Act
FS Forest Service
GPM gallons per minute
FWS Fish and Wildlife Service
HRS Hazard Ranking System
ICSs individual control strategies
IM instruction memorandum
kg kilogram
MCL maximum contaminant level
mg/1 milligrams per liter
MSHA Mine Safety and Health Administration
NAAQS National Ambient Air Quality Standards
NEPA National Environmental Policy Act
NESHAP National Emission Standards for Hazardous Air Pollutants
NIOSH National Institute for Occupational Safety and Health
NMEID New Mexico Environmental Improvement Division
NPDES National Pollutant Discharge Elimination System
NPL National Priorities List
NPS National Park Service
NSPSs new source performance standards
NTIS National Technical Information Service
oz/t troy ounces per ton
ppm parts per million
PSD prevention of significant deterioration
RCRA Resource Conservation and Recovery Act
RI/FS remedial investigation and feasibility study
RIP resin-in-pulp
ROD record of decision
SIPs State implementation plans
TSCA Toxic Substance Control Act
TDS total dissolved solids
TSS total suspended solids
UCL upper control limit
USC United States Code
US DOI United States Department of the Interior
US EPA United States Environmental Protection Agency
USGS United States Geological Survey
UMTRCA Uranium Mill Tailings Remediation Control Act
B-l
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Mining Industry Profile: Uranium
APPENDIX C
GROUNDWATER STANDARDS FOR REMEDIAL ACTIONS AT INACTIVE URANIUM
PROCESSING SITES (60 FEDERAL REGISTER 2854, JANUARY 11, 1995)
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FEDERAL REGISTER
Vol. 60, No. 7
Rules and Regulations
ENVIRONMENTAL PROTECTION AGENCY (EPA)
40 CFR Part 192
[FRL-3510-1]
RIN 2060-AC03
Groundwater Standards for Remedial Actions at Inactive Uranium Processing Sites
Part IV
60 PR 2854
DATE: Wednesday, January 11, 1995
ACTION: Final rule.
To view the next page, type .np* TRANSMIT.
To view a specific page, transmit p* and the page number, e.g. p*l
SUMMARY: The Environmental Protection Agency is issuing In 1994, EPA issued final
regulations to correct and prevent contamination of groundwater beneath and in the
vicinity of
inactive uranium processing sites by uranium tailings. EPA first issued regulations
(40 CPR part 192, subparts A, B, and C) for cleanup and disposal of tailings
from these sites on January 5, 1983. These new regulations replace existing
provisions at 40 CFR 192.20(a)(2) and (3) that were remanded by the U.S. Court
of Appeals for the Tenth Circuit on September 3, 1985. They are promulgated
pursuant to Section 275 of the Atomic Energy Act, as amended by Section 206 of
the Uranium Mill Tailings Radiation Control Act of 1978 (Public Law 95-604) .
The regulations apply to tailings at the 24 locations that qualify for
remedial action under Title I of Public Law 95-604. They provide that tailings
must be stabilized and controlled in a manner that permanently eliminates or
minimizes contamination of groundwater beneath stabilized tailings, so as to
protect human health and the environment. They also provide for cleanup of
contamination that occurred before the tailings are stabilized.
EFFECTIVE DATE: February 10, 1995.
ADDRESSES: Background Documents. A report ("Groundwater Protection Standards for
Inactive Uranium Tailings Sites, Background Information for Final Rule," EPA
520/1-88-023) has been prepared in support of these regulations. Another report
("Groundwater Protection Standards for Inactive Uranium Tailings Sites, Response
to Comments," EPA 520/1-88-055) contains the detailed responses of the
Environmental Protection Agency to comments on the standard by the reviewing
public. Single copies of these documents may be obtained from the Program
Management Office (6601J), Office of Radiation and Indoor Air, U.S.
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60 FR 2854, *
Environmental Protection Agency, Washington, DC 20460; (202) 233-9354,
Docket. Docket Number R-87-01 contains the rulemaking record. The docket is
available for public inspection between 8 a.m.-4 p.m., weekdays, at EPA's
Central Docket Section (LE-131), Room M-1500, 401 M Street SW., Washington, DC
20460. A reasonable fee may be charged for copying.
FOR FURTHER INFORMATION CONTACT: Allan C.B. Richardson, Criteria and Standards
Division 16602J), Office of Radiation and Indoor Air, U.S. Environmental
Protection Agency, Washington, DC 2046Q; telephone (202) 233-9213.
SUPPLEMENTARY INFORMATION:
I . Introduction
On November 8, 1978, Congress enacted the Uranium Mill Tailings Radiation
Control Act of 1978 (henceforth called "UMTRCA"). In UMTRCA, Congress found that
uranium mill 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 of such tailings in order to prevent or minimize
radon diffusion into the environment and to prevent or minimize other
environmental hazards from such tailings." The Act directs the Administrator of
the Environmental Protection Agency (EPA) to set "* * * standards of general
application for the protection of the public health, safety, and the environment
* * *" to govern this process of stabilization, disposal, and control.
UMTRCA directs the Department of Energy (DOE) to conduct such remedial
actions at the inactive uranium processing sites as will insure compliance with
the standards established by EPA. This remedial action is to be selected and
performed with the concurrence of the Nuclear Regulatory Commission (NRC). Upon
completion of the remedial action program, the depository sites will remain in
the custody of the Federal government under an NRC license.
The standards apply to residual radioactive material at the 24 processing
sites designated, as provided in the Act, by DOE. Residual radioactive material
is defined as any wastes which DOE determine to be radioactive, either in the
form of tailings resulting from the processing of ores for the extraction of
uranium and other valuable constituents of the ores, or in oth«r forms which
relate to such processing, such as sludges and captured contaminated water from
these sites. (Additional wastes that do not meet this definition may be subject
to regulation as hazardous waste under the Solid Waste Disposal Act (SWDA) as
amended by the Resource Conservation and Recovery Act of 1976 iRCRA).)
Standards are required for two types of remedial actions: disposal and
cleanup of residual radioactive material. Disposal is here used, to mean the
operation that places tailings in a permanent condition which will minimize risk
of harmful effects to the health of people and harm to the environment. Cleanup
is the operation that eliminates, or reduces to acceptable levels, the potential
health and environmental consequences of tailings or their constituents that
have been dispersed from tailings piles or disposal areas by natural forces or
by human activity, through removal of residual radioactive materials from land,
buildings, and groundwater.
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60 FR 2854, *
On January 5, 1983, EPA promulgated final standards for the disposal and
cleanup of the inactive mill tailings sites under UMTRCA (48 FR 590). These
standards were challenged in the Tenth Circuit Court of Appeals by several
parties (Case Nos. 83-1014, 83-1041, 83-1206, and 83-1300). On September 3,
1985, the court dismissed all challenges except one: it set aside the
groundwater provisions of the regulations at 40 CFR 192.20(a)(2) and (3) and
remanded them to EPA "* * * to treat these toxic chemicals that pose a
groundwater risk as it did in the active mill site regulations." On September
24, 1987, EPA proposed new standards to replace those remanded. A public hearing
was held in Durango, Colorado, on October 29, 1987. In response to requests from
several commenters at the public hearing and a later request by the American
Mining Congress, the public record for comments on the proposed standard was not
closed until January 29, 1988. With this notice, EPA is establishing final
standards to replace those set aside.
II. Summary of Background Information
Beginning in the 1940's, the U.S. Government purchased large quantities of
uranium for defense purposes. As a result, large piles of tailings were created
by the uranium milling industry. Tailings piles pose a hazard to public health
and the environment because they contain radioactive and toxic constituents
which emanate radon to the atmosphere and may leach into groundwater. Tailings,
which are a sand-like material, have also been removed from tailings piles in
the past for use in construction and for soil [*2855] conditioning. These
uses are inappropriate, because the radioactive and toxic constituents of
tailings may elevate indoor radon levels, expose people to gamma radiation, and
leach into ground and surface waters.
Most of the mills are now inactive and many of the sites were abandoned.
These abandoned sites are being remediated under Title I of UMTRCA. Congress
designated 22 specific inactive sites in Title I of UMTRCA, and the DOE
subsequently added two more. Most remaining uranium mill tailings sites are
regulated by the NRC or States and will be reclamated under Title II of UMTRCA.
(DOE also owns one inactive site at Monticello, Utah, that is not included under
UMTRCA). The Title I sites are located in the West, predominantly in arid areas,
except for a single site at Canonsburg, Pennsylvania. Before disposal operations
began, tailings piles at the inactive sites ranged in area from 5 to 150 acres
and in height from only a few feet to as much as 230 feet. The amount at each
site ranges from residual contamination to 2.7 million tons of tailings. The 24
designated Title I sites combined contain about 26 million tons of tailings
covering a total of about 1000 acres.
Under the provisions of Title I of UMTRCA, the DOE is responsible for the
disposal of tailings at these sites, which will then be licensed to DOE by NRC
for long term surveillance and maintenance, following NRC approval of the
remediation. In addition, tailings that were dispersed from the piles by natural
forces or that have been removed for use in or around buildings or on land are
being retrieved and replaced on the tailings piles prior to their disposal.
UMTRCA, as originally enacted, required that DOE complete all these remedial
actions within 7 years of the effective date of EPA's standards, that is, by
March 5, 1990. At the end of 1993 disposal actions had been completed at ten
sites: Canonsburg, Pennsylvania, one of two sites in areas of high precipitation
(Falls City, Texas is the other); Shiprock, New Mexico; Salt Lake City, Utah;
Lakeview, Oregon; Green River, Utah; Spook and Riverton, Wyoming; Lowman,
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60 FR 2854, * 2855
Idaho; Tuba City, Arizona; and Durango, Colorado. Disposal actions were well
advanced at eight other ,sites: Rifle (two piles), Grand Junc:ion, and Gunnison,
Colorado; Monument Valley, Arizona; Mexican Hat, Utah; Falls City, Texas; and
Ambrosia Lake, New Mexico. The remaining sites are in the advanced stages of
planning and should be under construction within the next two years. In view of
the rate of progress with remedial work, Congress in 1988 ext.ended the
completion date for disposal and most cleanup activities until September 30,
1994, and provided further "* * * that the authority of the Secretary to perform
groundwater restoration activities under this title is without limitation."
(Uranium Mill Tailings Remedial Action Amendments Act of 1986, P.L. 100-616,
November S, 1988; 42 U.S.C. 7916). Section 1031 of the Energy Policy Act of 1992
further extended the completion date for UMTRCA surface stabilization (disposal)
activities to September 30, 1996.
The most important hazardous constituent of uranium mill tailings is radium,
which is radioactive. Other potentially hazardous substances in tailings piles
include arsenic, molybdenum, selenium, uranium, and, usually in lesser amounts,
a variety of other toxic substances. The concentrations of these materials in
tailings vary from pile to pile, ranging from 2 to more than 100 times local
background soil concentrations. A variety of organics is also known to have been
used at these sites.
Exposure to radioactive and toxic substances may cause cancer and other
diseases, as well as genetic damage and teratogenic effects. Tailings pose a
risk to health because: (1) Radium in tailings decays into radon, a gaseous
radioactive element which is easily transported in air and the radioactive decay
products of which may lodge in the lungs; (2) individuals may be directly
exposed to gamma radiation from the radioactivity in tailings: and (3)
radioactive and toxic substances from tailings may leach into water and then be
ingested with food or water, or inhaled following aeration. It is the last of
these hazards that is primarily addressed here. (Although radon from radium in
groundwater is unlikely to pose a substantial hazard at these locations, these
standards also address that potential hazard.) The other hazards are covered by
existing provisions of 40 CFR part 192.
EPA's technical analysis was based on detailed reports for 14 of the 24
inactive uranium mill tailings sites that had been developed by late 1988 for
the Department of Energy by its contractors. Preliminary data for the balance of
the sites were also examined. Those data showed that the voluires of contaminated
water in aquifers at the 24 sites range from a few tens of millions of gallons
to 4 billion gallons. In a few instances mill effluent was apparently the sole
source of this groundwater. Each of the 14 sites examined in detail had at least
some groundwater contamination beneath and/or beyond the site. In some cases the
groundwater upgradient of the pile already exceeded EPA drinking water standards
for one or more contaminants due to mineralization sources or due to
anthropogenic sources other than the uranium milling activities, thus making it
unsuitable for use as drinking water without treatment and, in some extreme
cases, for most other purposes before it was contaminated by effluent from the
mill. Some contaminants from the tailings piles are moving offsite quickly and
others are moving slowly. The time for natural flushing of the contaminated
portions of these aquifers was estimated to vary from a couple of years to many
hundreds of years. Active restoration was estimated to take from less than 5
years at most sites to approximately 50 years at one site.
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60 FR 2854, *2855
DOE currently estimates that there is approximately 4.7 billion gallons of
contaminated water, but this estimate does not include all sites. One site,
Lowman, Idaho, shows no sign of contamination related to the processing
activities, while the site with the largest amount of contamination, Monument
Valley, Arizona, has an estimated 0.75 billion gallons of contaminated water
The DOE estimate does not include those sites where current assessments indicate
that supplemental standards should be applied, because contamination at these
sites has been hard to quantify.
Contaminants that have been identified in the groundwater downgradient from a
majority of the sites include uranium, sulfate, iron, manganese, nitrate,
chloride, molybdenum, selenium, and total dissolved solids. Radium, arsenic,
fluoride, sulfide, chromium, cadmium, vanadium, lead, and copper have also been
found in the groundwater at one or more sites.
UMTRCA requires that the standards established under Title I provide
protection that is consistent, to the maximum extent practicable, with the
requirements of RCRA. In this regard, regulations established by EPA for
hazardous waste disposal sites under RCRA provide for the specification of a
groundwater protection standard for each waste management area in the facility
permit (see 40 CFR part 264, subpart F). The groundwater protection standard
includes a list of specific hazardous constituents relevant to each waste
management area, a concentration limit for each hazardous constituent, the point
of compliance, and the compliance period. The subpart F regulations specify that
the concentration limits may be set at [*2856] general numerical limits
(maximum concentration limits (MCLs)) for some hazardous constituents or at
their background level in groundwater unless alternate concentration limits
(ACLs) are requested and approved. ACLs may be requested based upon data which
would support a determination that, if the ACL is satisfied, the constituent
would not present a current or potential threat to human health and the
environment. This standard incorporates many of these provisions into the
regulations for the Title I sites.
III. Changes and Clarifications in Response to Comments
These final standards modify and clarify some of the provisions of the
proposed standards as a result of information and views submitted during the
comment period and at the public hearing. EPA received many comments on the
proposed standards. Twenty-three letters were received and eight individuals
testified at the public hearing. Comments were submitted from private citizens,
public interest groups, members of the scientific community, and representatives
of industry and of State and Federal agencies. EPA has carefully reviewed and
considered these comments in preparing its detailed Response to Comments and the
final Background Information Document and in developing the final standards.
EPA's responses to major comments are summarized below.
Uranium Concentration Limit
Several commenters pointed out that the Agency used inappropriate dose
conversion values (nonstochastic) for uranium and radium (instead of the more
appropriate stochastic values) in developing the proposed concentration limit
for uranium. These comments were correct. We have reevaluated the risks
associated with ingestion of uranium, using current risk factors for
radiocarcinogenicity of uranium, and have also considered the chemical toxicity
of uranium. We have concluded that the level proposed, 30 pCi/liter, provides
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SO FR 2854, *2856
an adequate margin of safety against both carcinogenic and toxic effects of
cranium, and tnat the level should be expressed in terms of the concentration of
radioactivity, because it is related to the principal health risk, and can
acc^T-nodate different levels of radioactive disequilibrium between uranium-234
and uranium-238.
EPA's Office of Groundwater and Drinking Water has also examined these
factors, and, on July 18, 1991, proposed the MCL for uranium in drinking water
be set at a chemical concentration comparable to the limit on radioactivity
promulgated in this regulation. Should the MCL for drinking water, as finally
promulgated, provide a level of health protection different ::rom that provided
by the limit in this regulation, EPA will reconsider the lim:.t at that time. On
the basis of the above considerations, the limit for uranium has been
established at 30 pCi/liter for this regulation.
Molybdenum Concentration Limit
Several reviewers objected to the proposed inclusion of a limit on
molybdenum. They pointed out that EPA has not established a drinking water
standard for this element. While this is true, the drinking water regulations
also make provision for health advisories in the case of contaminants that are
problems only in special situations. Molybdenum in the vicinity of uranium mill
tailings is such a special case. Uranium mill tailings often contain high
concentrations of molybdenum that can leach into groundwater in concentrations
that may cause toxic effects in humans and cattle. This rule therefore continues
to contain a limit on the concentration of molybdenum in groundwater. The value
chosen remains the same as that proposed, as discussed in Section IV below.
Other Groundwater Limits
These groundwater limits incorporate MCLs issued under the Safe Drinking
Water Act (SDWA) (42 USC 300f, et seq.) and in effect for sites regulated under
RCRA from the time these limits were proposed on September 24, 1987, to the
present. However, on January 30, 1991, EPA issued new MCLs for some of the
inorganic constituents included in the present limits, and proposed new drinking
water standards for radioactive constituents were published on July 18, 1991 (56
FR 3526 and 33050). Following publication of final drinking water standards for
radioactive constituents, EPA will consider whether the benefi.ts and costs
implied by differences between these limits and the new drinking water standards
warrant proposing to incorporate the new values into both the Title I and the
Title II limits for groundwater.
Application of These Regulations to Vicinity Properties
Several commenters questioned the wisdom of applying these regulations to
vicinity properties. (Vicinity properties are real properties or improvements in
the vicinity of a tailings pile that are determined by DOE, in consultation with
the NRC, to be contaminated with residual radioactive materials.) They indicated
that if the portion of the proposed rule requiring detailed assessment and
monitoring were applied to all vicinity properties, it would greatly expand the
cost of the program without providing additional benefits. Sin=e only a few
vicinity properties contain sufficient tailings to constitute a significant
threat of groundwater contamination, we have concluded that derailed assessment
and monitoring, followed by identification of listed constituents and
groundwater standards, is not required at all vicinity properties. It is
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60 FR 2854, *2856
necessary only at those vicinity properties with a significant potential for
groundwater contamination, as determined by the DOE (with the concurrence of
NRC) using factors such as those in EPA's RCRA Facility Assessment Guidance
document. It should be noted that this modification applies to the requirement
for detailed assessment and monitoring only,- the standards for cleanup of
groundwater contamination are not changed. In addition, we note that the minimal
quantities of residual radioactive materials left behind at vicinity properties
after compliance with subpart B do not constitute disposal sites under subpart
A.
Application of State Regulations to These Sites
Some commenters expressed the view that these regulations should require
consistency with State laws and regulations. EPA's regulations for licensed mill
tailings sites under Title II of this Act do not contain such a provision.
(Although NRC Agreement States may, under the Atomic Energy Act, adopt standards
which "* * * are equivalent to the extent practicable or more stringent * * *,"
they have not done so under UMTRCA.) We have decided that decisions regarding
consistency with State laws and regulations should be made by DOE in
consultation with the States, as provided by Section 103 of the Act. In making
these decisions in cases where an approved Wellhead Protection Area, under the
Safe Drinking Water Act, is associated with the site, however, DOE must comply
with the provisions of that program, unless an exemption is granted by the
President of the United States. In addition, contamination on the site that is
not covered by UMTRCA (because it is not related to the processing operation)
may be covered by Federal or State RCRA programs.
Application of Institutional Controls During an Extended Remedial Period
Several comments were received concerning the effectiveness, reliability,
t*2857] and enforceability of institutional controls to be applied during a
remedial period that has been extended to take advantage of natural flushing.
EPA recognizes that some institutional controls, such as advisories or signs,
although desirable as secondary measures, are not appropriate as primary
measures for preventing human exposure to contaminated water. For this reason,
the regulations permit institutional controls to be used in place of remediation
only when DOE is able to ensure their effectiveness will be maintained during
their use. The standards require that institutional controls "* * * effectively
protect public health and the environment and satisfy beneficial uses of
groundwater * * *" during their period of application. In this regard, we note
that tribal, state, and local governments can also play a key role in assuring
the effectiveness of institutional controls. In some cases this may be effected
through changes in tribal, state, or local laws to ensure the enforceability of
institutional controls by the administrative or judicial branches of government
entities. One State indicated that some institutional controls, such as deed
restrictions, should not be viewed as restrictions since they do not empower any
agency to prohibit access to contaminated water. However, judicial enforcement
of deed restrictions can be as effective as administrative enforcement of other
institutional controls by a government agency. Therefore, deed restrictions are
an acceptable institutional control if they are enforceable by a court with
jurisdiction over the site at which they are used, and if the implementing
agency will take appropriate steps to assure their effective application.
Some commenters expressed the view that, if institutional controls are used,
this use must be restricted to the 7-year period for remediation authorized in
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60 FR 2854. *28S°
Section 112 a,1 of UMTRCA EPA believes that it is not possible to achieve
cleanup of groundwater at all of the sites within 7 years, no matter what
r~ -1 a"iat ion scherpe is employed. It is therefore necessary to consider time
f';---i--53 other than that originally contemplated in UMTRCA for completion of
remedial actions. Congress, in granting an extension of the authorization in
Section 112 (a) of UMTRCA for disposal and cleanup actions from March 5, 1990 to
September 30, 1994, provided further "* * * that the authority of the Secretary
to perform groundwater restoration activities under this title is without
limitation." (Uranium Mill Tailings Remedial Action Amendments Act of 1988 (42
U.S.C. 7916)). In addition, under Section 104 (f) (2) of the Act (42 U.S.C.
7919 (f) (2)), the NRC may require maintenance of corrective and institutional
measures that are already in place at the time authorization under Section
112 (a) expires, without time limitation.
The provisions for use of natural flushing when appropriate institutional
controls are in place are consistent with existing regulations under Title II,
although they are not explicit in those regulations. In cases where groundwater
contamination is detected, the Title II regulations specify when corrective
actions must begin, but do not specify a time when corrective actions must be
completed. These provisions under Title I provide additional guidance on the
length of time over which institutional control may reasonably be relied upon,
and further guidance on the kinds of institutional provisions that would be
appropriate at any uranium tailings site. In addition, use of institutional
controls is not limited to extended remedial periods. Interim institutional
controls may also be used to protect public health or the environment, when DOE
finds them necessary and appropriate, prior to commencing active remedial
action, during active remedial action, or during implementation of other
compliance strategies.
Other comments addressed a variety of matters, including the monitoring of
institutional controls, the relationship between long-term maintenance
responsibilities and the 100-year limit on use of institutional controls, types
of institutional controls, longer or shorter extended remedial periods, and the
legality of institutional controls under UMTRCA. These matters! are addressed in
the Response to Comments, published separately as a background document.
Point of Compliance
Several commenters objected to the definition of the point of compliance in
the disposal standards (subpart A), and suggested that it be defined at some
finite distance from the edge of the remediated tailings instead of at the
downgradient edge of the pile, as in regulations established under RCRA. They
indicated that the remediated tailings may seep a minor amount of contamination,
which may cause the standards to be exceeded at the proposed point of
compliance, under conditions where there would be no detriment to human health
or the environment at small distances away. This difficulty can be solved, as
proposed, by moving the point of compliance or, alternatively, by granting an
ACL if it can be shown that such levels of contamination will not impair human
health or damage the environment. We have concluded the latter is more in
keeping with the regulations established under RCRA. The standards provide that
DOE may request an ACL under such circumstances and NRC may approve such a
request if contamination of groundwater will not endanger huma.i health or
degrade the environment. It is our view that this requirement would usually be
satisfied at any site where the minor seepage noted above is not projected to
extend beyond a few hundred meters from the waste management area and will not
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60 FR 2854, *2857
extend outside the site boundary. This could occur under a variety of
circumstances where important roles are played by attenuation, dilution, or by
vapor transport in unsaturated zones
Under the cleanup standard (subpart B), the DOE is required to characterize
the extent of contamination from the site and clean it up wherever it exceeds
the standards. This characterization and confirmation of cleanup will be carried
out through the monitoring program established under ® 192. 12 (c) (3) . Although
the DOE is not required to clean up preexisting contamination that is located
beneath a remediated tailings pile, they are required to consider this
contamination when developing their plants) for remedial action and will have to
clean up any contamination that will migrate from beneath the pile and exceed
the concentration limits established in accordance with @ 192.02(c) (3).
Alternate Concentration Limits
Several reviewers commented that EPA should not, for a variety of reasons,
delegate the responsibility for approving ACLs to the NRC. Others stated that
the standards were so strict that ACLs would be needed at every site. EPA
considered a number of approaches to the provision for granting ACLs. These
included deleting 'the ACL provision, establishing (by regulation) generic
criteria for ACLs to be implemented by NRC, providing for some form of EPA
review or oversight of ACL implementation, and (as in the proposed regulation)
providing for no EPA role in setting ACLs at individual sites.
EPA has decided not to delete the ACL provision because it is clearly needed,
if for no other reason than to deal with the possibilities of unavoidable minor
projected seepage over the extremely long-term design life (1000 years) of the
disposal required, in most cases, by these standards, and of [*2858] cleanup
situations involving pollutants for which no MCLs exist. Establishment of a
complete set of regulations specifying generic criteria for granting ACLs
presents difficulties for rulemaking, since ACL determinations often involve
complex judgments that are not amenable to being reduced to simple regulatory
requirements. In this regard we note that such regulations do not yet exist in
final form for sites directly regulated under RCRA. However, the Agency has
issued interim final Alternate Concentration Limit Guidance (OSWER Directive
9481.00; EPA/SW-87-017), and has proposed several relevant rules, e.g., under 40
CFR parts 264, 265, 270, and 271, for Corrective Action for Solid Waste
Management Units at Hazardous Waste Management Facilities (55 FR 30798; July 27,
1990) . In addition, the NRC proposed a draft Technical Position on Alternate
Concentration Limits for Uranium Mills at Title II sites on March 21, 1994 (59
FR 13345). EPA has reviewed the NRC draft Technical position, and we find that
it is consistent, in general, with EPA'a own guidance and proposed rules. The
NRC draft position does not, however, specify an upper limit on risks to humans
from carcinogens. We have reconsidered the issue of EPA review or oversight of
ACLs at Title I sites in light of this review, and concluded that, in the
interests of assuring that public health is adequately protected while at the
same time minimizing the regulatory burden on DOE, the best course of action is
to specify that upper limit in this regulation and assign the responsibility for
making determinations for ACLs at individual sites to NRC. Accordingly, in this
rule, in the implementing guidance contained in subpart C, @ 192.20(a) (2), we
now specify that the criterion for known or suspected carcinogens contained in
the above-referenced RCRA documents should be applied in granting ACLs. That
criterion specifies that ACLs should be established at levels which represent an
excess lifetime risk, at a point of exposure, no greater than 10 supra -4 to
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60 FR 2854, -2858
1C supra -6 to an average individual.
EPA is required by UMTRCA (Section 206) to be consistent, to the maximum
extent practicable, with RCRA. For this reason, relevant portions of the RCRA
regulations have been incorporated. For example, these regulations provide for
the use of ACLs when it can be shown that the criteria specified in @
192.02(c)(3)(ii) are satisfied. It remains the view of the Agency that, as at
the Title II sites, an ACL is appropriate if the NRC has determined that these
criteria are satisfied when the otherwise applicable standard will be met within
the site boundary (or at a distance of 500 meters, if this ia closer). It is
clear that ACLs will usually be appropriate to accommodate the controlled minor
seepage anticipated from properly designed tailings disposal within such
distances, when public use is not possible.
Cost
Greater consideration of cost and cost-benefit analysis was requested by
several commenters. In 1983, Congress amended UMTRCA to provide that when
establishing standards the Administrator should consider, among other factors,
the economic costs of compliance. We have considered these costs in two ways.
First, we compared them to the benefit, expressed in terms of the value of the
product-processed uranium ore-which has led to contamination of groundwater at
these sites. We estimate the present value of the processed uranium ore from
these sites as approximately 3.9 billion dollars (1989 dollars). The estimated
cost of compliance is approximately 5.5% of this value, and we judge this to be
a not unreasonable incremental cost for the remediation of contamination from
the operations which produced this uranium. As a second way of. considering the
economic costs of compliance, we examined the cost of alternat.ive ways to supply
the resources for future use represented by these groundwaters. As noted
earlier, water is a scarce resource in the Western States where this cleanup
would occur. When other resources have been exhausted, the only remaining
alternative to cleaning up groundwater in the vicinity of these sites is to
replace this water by transporting water from the nearest alternative source.
Our analysis of the costs of doing this indicates that it is significantly more
costly to supply water from alternative sources than it would be to clean up the
groundwater at these sites. We have concluded, therefore, that this final rule
involves a reasonable relationship between the overall costs aid benefits of
compliance.
The RCRA subpart F regulations do not include cost as a consideration for the
degree of cleanup of groundwater, and these regulations also do not provide for
site-specific standards based on site-specific costs. Nonetheless, it is clearly
desirable and appropriate to apply the most cost-effective remedies available to
meet these standards at each site, and we anticipate that DOE will make such
choices in choosing the remedies it applies to satisfy these standards. Further,
once the basic criteria for establishing ACLs set forth in ® lS2.02(c)(3)(ii)(B)
have been satisfied, if a higher level of protection is reasonably achievable,
this should be carried out. However, we do not believe it is appropriate to
apply detailed cost/benefit balancing judgments to justify lesser levels of
protection for ground water. The benefits of cleaning up groundwater are often
not quantifiable and may not become known for many years; therefore,
site-specific cost-benefit analyses are difficult to apply in sach situations.
Moreover, Congress provided no authority that protection of ground water at each
site should be limited by cost/benefit considerations, even after reconsidering
the question in the 1984 amendments.
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60 FR 2854, *2858
Some reviewers raised the issue of additional costs arising from use of these
standards in other applications, such as CERCLA cleanups. We recognize that
there may be costs associated with using these standards as precedents for other
waste cleanup projects. However, the reasonableness of incurring such costs
should be assessed when it is possible to do so with complete information, that
is, at the time of application of these standards as precedents for situations
other than the one for which they were developed.
Natural Restoration
The use of natural restoration of an aquifer was discussed by several
reviewers. Some felt that it was a viable and desirable alternative, because it
is easy and inexpensive to apply, for groundwaters that are not expected to be
used for drinking or other purposes during the cleanup period. Others felt that
it should be prohibited because it required a reliance on institutional controls
and would circumvent active cleanup of groundwater. EPA believes that the use of
natural restoration can be a viable alternative in situations where water use
and ecological considerations are not affected, and cleanup will occur within a
reasonable time. We have concluded that institutional controls, when enforced by
government entities, or that otherwise have a high degree of permanence, can be
relied on for periods of time up to 100 years, and that adequate safeguards are
provided through NRC oversight of the implementation of these standards to
prevent this alternative from being used to circumvent active cleanup of water
that will be used by nearby populations.
Commenters suggested that natural restoration was not adequate to restore
water quality at these sites. DOE has indicated that they expect that natural
restoration may be all that is necessary at up to eight sites and could be used
[*2859] in conjunction with active remedial measures at several other sites.
Natural restoration is most valuable when the contaminated aquifer discharges
into a surface water body that will not be adversely affected by the
contamination.
Pile and Liner Design
The design of the remediated pile and the use of a liner was of concern to
several commenters, and recommendations were given for suitable designs. These
commenters feared that water would continually infiltrate the remediated piles
and contaminate groundwater.
These EPA standards would not be satisfied by designs which allow
contamination that would adversely affect human health or the environment.
Further, current engineering designs for covers incorporate a number of features
that control infiltration to extremely low levels. These may include an erosion
barrier (with vegetation, where feasible) to transpire moisture and reduce
infiltration; rock filters and drains to drain and laterally disperse any
episodic infiltration; very low permeability infiltration barriers to intercept
residual infiltration; and finally, the thick radon barrier, which further
inhibits infiltration. The combined effect of these features is to reduce the
overall hydrological transmission of covers to levels on the order of one part
in a billion, with a resulting high probability that there will be no saturated
zone of leachate in or below the tailings. EPA expects DOE to use such
state-of-the-art designs wherever it is appropriate to do so because of the
proximity of groundwater.
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SO FR 2854, *2859
Under the provisions of UMTRCA, the detailed design of the pile and its cover
is the responsibility of DOE, and confirmation of the viability of the design to
satisfy EPA's standards is the responsibility of NRC. EPA's responsibility is to
promulgate the standards to which the disposal must conform. It would be
inconsistent with the division of responsibilities set forth in UMTRCA to
specify actual designs for the piles in. these regulations. In this connection,
the requirement to provide a liner when tailings are moved to a new location in
a wet state is properly seen as a generic management requirement. Any liner for
this purpose would only serve a useful purpose for the relati/ely short time
over which the moisture content of the pile adjusts to its loig-term equilibrium
value, after which the cover design would determine the groundwater protection
capability of the disposal.
Restricted List of Constituents
Commenters were overwhelmingly opposed to a restricted list of radioactive or
toxic constituents and recommended that the entire list of constituents be
relied upon. It is the Agency's experience that, under RCRA, no changes in this
list have been requested based on the criteria provided in @ 264.93 (b) . These
criteria allow for hazardous constituents to be excluded based on a
determination that the constituent does not pose a substantial present or
potential hazard to human health or the environment. Therefore, that portion of
the RCRA standards which specify conditions for the exclusion of constituents
from the RCRA list of hazardous constituents has been excluded as unnecessary.
However, a short list of compounds has been developed by EPA for use in
monitoring groundwater under RCRA. This rule incorporates that: list of
constituents (Appendix IX of part 264) in place of the complete list in Appendix
I for the monitoring programs required at @@ 192.02 (c) (1), 19:!. 03, and
192.12 (c) (1) . However, the rule still requires that all hazardous constituents
listed in Appendix I be considered when corrective action is necessary.
IV. Summary of the Final Standard
»
These final standards consist of three parts: a first part governing
protection against future groundwater contamination from tailings piles after
disposal; a second part that applies to the cleanup of contamination that
occurred before disposal of the tailings piles; and a third pairt that provides
guidance on implementation and specifies conditions under which supplemental
standards may be applied.
A. The Groundwater Standard for Disposal
The standard for protection of groundwater after disposal Isubpart A) is
divided into two parts that separately address actions to be carried out during
periods of time designated as the disposal and post-disposal periods. The
disposal and post-disposal periods are defined in a manner analogous to the
closure and post-closure periods, respectively, in RCRA regulations. However,
there are some differences regarding their duration and the timing of any
corrective actions that may become necessary due to failure of disposal systems
to perform as designed. (Because there are no mineral processing activities
currently at these inactive sites, standards are not needed for an operational
period.) The disposal period, for the purpose of this regulation, is defined as
that period of time beginning on the effective date of the original Title I part
192 standard for the inactive sites (March 7, 1983) and ending with completion
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PAGE 14
60 FR 2854, *2859
of all actions related to disposal except post-disposal monitoring and any
corrective actions that might become needed as a result of failure of completed
disposal. The post-disposal period begins with completion of disposal actions
and ends after an appropriate period for the monitoring of groundwater to
confirm the adequacy of the disposal. The groundwater standard governing the
actions to be carried out during the disposal period incorporates relevant
requirements from subpart F of part 264 of this chapter (@@ 264.92-264.95) . The
standard for the post-disposal period reflects relevant requirements of @
264.111 of this Chapter. The disposal standard also includes provisions for
monitoring and any necessary corrective action during both disposal and
post-disposal periods. These provisions are essentially the same as those
governing the licensed (Title II) uranium mill tailings sites (40 CFR 192,
subparts D and E; see also the Federal Register notices for those standards
published on April 29, 1983 and on October 7, 1983) . Several additional
constituents are regulated, however, in these final Title I regulations.
These regulations do not change existing requirements at Title I sites for
the period of time disposal must be designed to comply with the standards, and
therefore remain identical to the requirements for licensed (Title II) sites in
this respect. The Agency also recently promulgated final regulations for spent
nuclear fuel, and high level and transuranic radioactive wastes (40 CFR part
191; 58 FR 66398, December 20, 1993). Those standards specify a different design
period for compliance (10,000 years versus 1000 years) for two principle
reasons: (1) The level of radioactivity, and therefore the level of health risk,
in the wastes addressed under 40 CFR part 191 is many orders of magnitude
greater than those addressed here. (The radioactivity of tailings is typically
0.4 to 1.0 nCi/g, 40 CFR part 191 wastes are always greater than 100 nCi/g, and
are typically far higher.) (2) The volume of uranium mill tailings is far
greater than the waste volumes addressed under 40 CFR part 191. The containment
that would be required to meet a 10,000 year requirement is simply not feasible
for the volumes of tailings involved (the option of underground disposal was
addressed and rejected in the original [*2860] rulemakings for the Title I
and Title II sites).
These regulations require installation of monitoring systems upgradient of
the point of compliance (i.e., in the uppermost aquifer upgradient of the edge
of the tailings disposal site) or at some other point adequate to determine
background levels of any listed constituents that occur naturally at the site.
The disposal should be designed to control, to the extent reasonably achievable
for 1000 years and, in any case, for at least 200 years, all listed constituents
identified in residual radioactive materials at the site to levels for each
constituent derived in accordance with @ 192.02(c)(3). Accordingly, the elements
of the groundwater protection standard to be specified for each disposal site
include a list of relevant constituents, the concentration limits for each such
constituent, and the compliance point.
These standards provide for consideration of ACLs if the disposal cannot
reasonably be designed to assure conformance to background levels (or those in
Table 1) over the required term. ACLs can be granted provided that, after
considering practicable corrective actions, a determination can be made that it
satisfies the values given by implementing the conditions for ACLs under @
192.02(c) (3) (ii) .
The standards for Title II sites require use of a liner under new tailings
piles or lateral extensions of existing piles. These standards for remedial
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PAGE 15
SO FR 2854, *2860
action at the inactive Title I sites do not contain a similar provision EPA
assumes that the inactive piles will not need to be enlarged. Several, however,
will be relocated. However, unlike tailings at the Title II s.ites, which
generally may contain large amounts of process water, the inactive tailings
contain little or no free water. Such tailings, if properly located and
stabilized with a cover adequate to ensure an unsaturated zone, are not likely
to require a liner in order to protect groundwater.
However, a liner would be needed for an initial drying-out period to meet
these groundwater standards if a situation arose where the ta:.lings initially
contained water above the level of specific retention. For example, tailings to
which water was added to facilitate their removal to a new site (i.e., through
slurrying), or for compaction during disposal. (It is anticipated that piles
will never be moved to areas of high precipitation or situated within a zone of
water table fluctuation.) Section 192.20(a)(3) requires the remedial plan to
address how any such excess water in tailings would be dealt with. In such
circumstances it will normally be necessary to use a liner or equivalent to
assure that groundwater will not be contaminated while the moisture level in the
tailings adjusts to its long-term equilibrium value. Currently, however, DOE
plans do not include slurrying any tailings to move them to ne'W locations.
Further, for all but two sites, of which one has already been closed
(Canonsburg) and at the other (Falls City) disposal actions are well advanced,
the tailings are located in arid areas where annual precipitation is low.
Disposal designs which prevent migration of listed constituents in the
groundwater for only a short period of time would not provide appropriate
protection. Such approaches simply defer adverse groundwater effects. Therefore,
measures which only modify the gradient in an aquifer or create barriers (e.g.,
slurry walls) would not of themselves provide an adequate disposal.
Section 192.02(d) requires that a site be closed in. a manner that minimizes
further maintenance. Depending on the physical properties of the sites,
candidate disposal systems, and the effects of natural processes over time,
measures required to satisfy these standards will vary from site to site. Actual
site data, computational models, and prevalent expert judgment may be used in
deciding that proposed measures will satisfy the standards. Under the provisions
of Section 108(a) of UMTRCA, the adequacy of these judgments is determined by
the NRC.
For the post-disposal period, a groundwater monitoring plan is required to be
developed and implemented. The plan will require monitoring for a period of time
deemed sufficient to verify, with reasonable assurance, the adequacy of the
disposal to achieve its design objectives for containment of listed
constituents. EPA expects this period of time to be comparable, in most cases,
to that required under @ 264.117 of Title 40 for waste sites regulated under
RCRA (i.e., a few decades). However, there may be situations where longer or
shorter periods are appropriate. Installation and commencement of the monitoring
required under @ 192.03 will satisfy this EPA standard, for the purposes of
licensing of the site by the NRC.
With regard to this monitoring, UMTRCA provides that, after remediation is
completed and custody is transferred to a Federal agency, NRC may require that
the Federal agency having custody of each remediated tailings site "* * *
undertake such monitoring, maintenance, and emergency measures * * *and other
actions as [NRC] deems necessary to comply with [EPA's standards]" (UMTRCA,
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60 FR 2854, *2860
Section 104 (f) (2)) . Although it is not intended that routine monitoring be
carried out as a requirement for conformance to these standards for the 200- to
1000-year period over which the disposal is designed to be effective, NRC may
require more extensive monitoring to comply with EPA's standards, as NRC deems
necessary under "8 104 (f) (2) of the Act.
During the post-disposal period, if listed constituents from a disposal site
are detected in excess of the groundwater standards, these regulations require a
corrective action program designed to bring the disposal and the groundwater
into compliance-with the provisions of @ 192.02 (c) (3) and subpart B,
respectively. In designing such a corrective action program, the implementing
agencies may consider all of the provisions available under subparts A, B, and
C. A modification of the monitoring program sufficient to demonstrate that the
corrective measures will be successful is also required. In designing future
corrective action programs, the implementing agencies may also wish to consider
the guidance provided by new regulations now being developed for the RCRA
program that will be proposed as subpart S to Title 40. However, the
requirements of Part 192 will still govern regulatory determinations of
acceptabil'ity.
Additional Regulated Constituents
For the purpose of this regulation only, the Agency is regulating, in
addition to the hazardous constituents referenced by @ 264.93, molybdenum,
nitrate, combined radium-226 and radium-228, and combined uranium-234 and
uranium-238. Molybdenum, radium, and uranium were addressed by the Title II
standards because these radioactive and/or toxic constituents are found in high
concentrations at many mill tailings sites. These regulations add numerical
limits for these constituents. Nitrate was added because it had been identified
in concentrations far in excess of drinking water standards in groundwater at a
number of the inactive sites.
The concentration limit for molybdenum in groundwater from uranium tailings
is set at 0.1 milligram per liter. This is the value of the provisional Adjusted
Acceptable Daily Intake (AADI) for drinking water developed by EPA under the
Safe Drinking Water Act (50 FR 46958). The Agency has established neither a
maximum concentration limit goal [*2861] (MCLG) nor a maximum concentration
limit (MCL) for molybdenum because it occurs only infrequently in water.
According to the most recent relevant report of the National Academy of Sciences
(Drinking Water and Health, 1980, Vol. Ill), molybdenum from drinking water,
except for highly contaminated sources, is not likely to constitute a
significant portion of the total human intake of this element. However, as noted
above, uranium tailings are often a highly concentrated source of molybdenum,
and it is therefore appropriate to include a standard for molybdenum in this
rule. In addition to the hazard to humans, our analysis of toxic substances in
tailings in the Final Environmental Impact Statement for Remedial Action
Standards for Inactive Uranium Processing Sites (EPA 520/4-82-013-1) found that,
for ruminants, molybdenum in concentrations greater than 0.05 ppm in drinking
water would lead to chronic toxicity. This concentration included a safety
factor of 10; the standard provides for a safety factor of 5, which we consider
adequately protective for ruminants.
The standard for combined uranium-234 and uranium-238 due to contamination
from uranium tailings is 30 pCi per liter. The level of health risk associated
with this standard is equivalent to the level proposed as the MCL for uranium
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PAGE 1"
60 FR 2854, *2861
in drinking water by EPA (56 FR 33050, July 18, 1991). The s landard promulgated
here applies to remedial actions for uranium tailings only. When the Agency has
established a final MCL for isotopes of uranium in drinking water, we will
consider whether this standard needs to be reviewed.
The limit for nitrate (as nitrogen) is 10 mg per liter. This is the value of
the drinking water standard for nitrate.
B. The Cleanup Standard
With the exception of the point of compliance provision, the standard
(subpart B) for cleanup of contaminated groundwater contains the same basic
provisions as the standard for disposal in subpart A. In addition, it provides
for the establishment of supplemental standards under certain conditions, and
for use of institutional control to permit passive restoration through natural
flushing when no public water system is involved.
Although the standards specify a single point of compliance for conforman.ee
to the groundwater standards for disposal, this does not suffice for the cleanup
of groundwater that has been contaminated before final disposal. Instead, in
this case compliance must be achieved anywhere contamination above the levels
established by these standards is found of is projected to be found in
groundwater outside the disposal area and its cover. The standards require DOE
to establish a monitoring program adequate to determine the extent of
contamination (@ 192.12(c) (1) ) in groundwater around each processing site. The
possible presence of any of the inorganic or organic hazardous constituents
identified in tailings or used in the processing operation should be assessed.
The plan for remedial action referenced under ® 192.20(b)(4) should document the
extent of contamination, the rate and direction of movement oE contaminants, and
consider future movement of the plume. The cleanup standards normally require
restoration of all contaminated groundwater to the levels provided for under ®
192.02(c) (3) . These levels are either background concentrations, the levels
specified in Table 1 in the rule, or ACLs. In cases where the groundwater is not
classified as of limited use, any ACL should be determined under the assumption
that the groundwater may be used for drinking purposes. In certain
circumstances, however, supplemental standards set at levels that would be
achieved by remedial actions that come as close to meeting the; otherwise
applicable standards as is reasonably achievable under the circumstances may be
appropriate. Such supplemental standards and ACLs are distinct, regulatory
provisions and may be considered independently. The regulations provide that
supplemental standards may be granted if:
. Groundwater at the site is of limited use (@ 192.11 (e)) in the absence of
contamination from residual radioactive materials; or
Complete restoration would cause more environmental harm than it would
prevent; or
. Complete restoration is technically impracticable from an engineering
perspective.
The use of supplemental standards for limited use groundwater applies the
groundwater classification system proposed in EPA's 1984 Groundwater Protection
Strategy. As proposed for use in these standards (52 FR 36003, September 24,
1987), Class III encompasses groundwaters that are not a current or potential
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PAGE 18
60 FR 2854, *2861
source of drinking water because of widespread, ambient contamination caused by
natural or human-induced conditions, or cannot provide enough water to meet the
needs of an average household. These standards adopt the proposed definition of
limited use groundwater. However, for the purpose of qualifying for supplemental
standards, human-induced conditions exclude contributions from residual
radioactive materials.
Water which meets the definition of limited use groundwater may,
nevertheless, reasonably be or be projected to be useful for domestic,
agricultural, or industrial purposes. For example, in some locations higher
quality water may be scarce or absent. Therefore, @ 192.22(d) requires the
implementing agencies to remove any additional contamination that has been
contributed by residual radioactive materials to the extent that is necessary to
preserve existing or reasonably projected beneficial uses in areas of limited
water supplies. At a minimum, at sites with limited use groundwater, the
supplemental standards require such management of contamination due to tailings
as is required to assure protection of human health and the environment from
that contamination. For example, if the additional contamination from the
tailings would cause an adverse effect on drinkable groundwater that has a
significant interconnection with limited use groundwater over which the tailings
reside, then the additional contamination from the tailings will have to be
abated.
Supplemental standards are also appropriate in certain other cases similar to
those addressed in Section 121(d)(4) of the Superfund Amendments and
Reauthorization Act of 1986 (SARA). SARA recognizes that cleanup of
contamination could sometimes cause environmental harm disproportionate to the
effects it would alleviate. For example, if fragile ecosystems would be impaired
by any reasonable restoration process (or by carrying a restoration process to
extreme lengths to remove small amounts of residual contamination), then it
might be prudent not to completely restore groundwater quality. Such a situation
might occur, for example, if the quantity of water that would be lost during
remediation is a significant fraction of that available in an aquifer that
recharges very slowly. Decisions regarding tradeoffs of environmental damage can
only be based on characteristics peculiar to the specific location of the site.
We do not yet know whether such situations exist in the UMTRCA program, but EPA
believes that use of supplemental standards should be possible in such
situations, after thorough investigation and consideration of all reasonable
restoration alternatives. [*2862]
Based on currently available information, we are not aware that at least
substantial restoration of groundwater quality is technically impracticable from
an engineering perspective at any of the designated sites. However, our
information is incomplete. For example, there may not be enough water available
in a very small aquifer to carry out remediation and retain the groundwater
resource, or, in other cases, some contaminants may not be removable without
destroying the aquifer. EPA believes that DOE should not be required to
institute active measures that would completely restore groundwater at these
sites if such restoration is technically impracticable from an engineering
perspective, and if, at a minimum, protection of human health and the
environment is assured. Consistent with the provisions of SARA for remediation
of waste sites generally, the standards therefore permit supplemental standards
in such situations at levels achievable by site-specific alternate remedial
actions. A finding of technical impracticability from an engineering perspective
requires careful and extensive documentation, including an analysis of the
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60 FR 2854, *2862
degree to which remediation is practicable. It should be noted that the phrase
"technically impracticable from an engineering perspective" means that the
remedial action cannot reasonably be put into practice; it does not mean a
conclusion derived from the balancing of costs and benefits. In addition to
documentation of technical matters related to cleanup technology, DOE should
als: include a detailed assessment of such site-specific matters as
t rar.smssivity of trie geologic formation, aquifer recharge and storage,
contaminant properties (e.g., withdrawal and treatability potential), and the
e
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60 FR 2854, *2862
by themselves include such measures as health advisories, signs, posts,
admonitions, or any other measure that requires the voluntary cooperation of
private parties. However, such measures may be used to complement other
enforceable institutional controls.
Restoration of groundwater may be carried out by removal, wherein the
contaminated water is removed from the aquifer, treated, and either disposed of,
used, or re-injected into the aquifer, and in situ , through the addition of
chemical or biological agents to fix, reduce, or eliminate the contamination in
place. Appropriate restoration will depend on characteristics of specific sites
and may involve use of a combination of methods. Water can be removed from an
aquifer by pumping it out through wells or by collecting the water from
intercept trenches. Slurry walls can sometimes be put in place to contain
contamination and prevent further migration of contaminants, so that the volume
of contaminated water that must be treated is reduced. The background
information document contains a more extensive discussion of candidate
restoration methods.
Previously EPA reviewed preliminary information for all 24 sites and detailed
information for 14 to make a preliminary assessment of the extent of the
potential applicability of supplemental standards and the use of passive
remediation. Approximately two-thirds of the sites appear to be located over
potable (or otherwise useful) groundwater and the balance over limited use
groundwaters. DOE, based on more recent information, feels that up to ten sites
are candidates for supplemental standards, and that the rate at which natural
flushing is occurring at up to eight of the sites permits consideration of
passive remediation under institutional control as the sole remedial method.
Some sites exhibit conditions that could be amenable to a combination of
strategies. Further, EPA is not able to predict the applicability of provisions
regarding technical impracticability or excess environmental harm, since this
requires detailed analysis of specific sites, but anticipates that wide
application is unlikely. It is emphasized that the above assessment is not based
on final results for the vast majority of these sites, and is, therefore,
subject to change.
RCRA regulations, for hazardous waste disposal units regulated by EPA,
provide that acceptable concentrations of constituents in groundwater (including
ACLs) are determined by the Regional Administrator (or an authorized State).
EPA's regulations under Title II of UMTRCA provide that the NRC, which regulates
active sites, replace the EPA Regional Administrator for the above functions
when any [*2863] contamination permitted by an ACL will remain on the
licensed site or within 500 meters of the disposal area, whichever is closer.
Because Section 108 (a) of UMTRCA requires the Commission's concurrence with
DOE's selection and performance of remedial actions to conform to EPA's
standards, this rule makes the same provision for administration by the NRC of
those functions for Title I as it did in the case of the Title II standards, and
also provides for NRC concurrence on supplemental standards.
V. Implementation
UMTRCA requires the Secretary of Energy to select and perform the remedial
actions needed to implement these standards, with the full participation of any
State that shares the cost. The NRC must concur with these actions and, when
appropriate, the Secretary of Energy must also consult with affected Indian
tribes and the Secretary of the Interior.
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60 FR 2854, *2863
The cost of remedial actions is being borne by the Federa!. Government and the
States as prescribed by UMTRCA. The clean-up of groundwater ;.s a large-scale
undertaking for which there is relatively little long-term experience.
Grcundwater conditions at the inactive processing sites vary greatly, and, as
noted above, engineering experience with some of the required remedial actions
is ^imited. Although preliminary engineering assessments have been performed,
specific engineering ^requirements and detailed costs to meet the groundwater
standards at each site have yet to be determined. We believe that costs
averaging about 10-15 million (1993) dollars for each of the approximately
fourteen tailings sites at which remedial action may be required are most
likely.
The benefits from the cleanup of this groundwater are difficult to quantify.
In some instances, groundwater that is contaminated by tailings is now in use
and will be restored. Future uses that will be preserved by cleanup are
difficult to project. In the areas where the tailings were processed,
groundwater is an important resource due to the arid condition of the land.
However, much of the contamination at these sites occurs in s.iallow alluvial
aquifers. At some of these sites such aquifers have limited use because of their
generally poor quality and the availability of better quality water from deeper
aquifers.
Implementation of the disposal standard for protection of groundwater will
require a judgment that the method chosen provides a reasonable expectation that
the provisions of the standard will be met, to the extent reasonably achievable,
for up to 1000 years and, in any case, for at least 200 years. This judgment
will necessarily be based on site-specific analyses of the properties of the
sites, candidate disposal systems, and the potential effects of natural
processes over time. Therefore, the measures required to satisfy the standard
will vary from site to site. Actual site data, computational models, and expert
judgment will be the major tools in deciding that a proposed disposal system
will satisfy the standard.
The purpose of the groundwater cleanup standard is to provide the maximum
reasonable protection of public health and the environment. Costs incurred by
remedial actions should be directed toward this purpose. We intend the standards
to be implemented using verification procedures whose cost and technical
requirements are reasonable. Procedures that provide a reasonable assurance of
compliance with the standards will be adequate. Measurements to assess existing
contamination and to determine compliance with the cleanup standards should be
performed with 1 reasonable survey and sampling procedures designed to minimize
the cost of verification.
The explanations regarding implementation of these regulations in @@
192.20 (a) (2) and (3) have been revised to remove those provisions that the Court
remanded and to reflect these new requirements.
These standards are not expected to affect the disposal work DOE has already
performed on tailings. On the basis of consultations with DOE a.nd NRC, we
expect, in general, that a pile designed to comply with the dissposal standards
proposed on September 24, 1987, will also comply with these disiposal standards
for the control of groundwater contamination. DOE will have to determine, with
the concurrence of the NRC, what additional work may be needed to comply with
the groundwater cleanup requirements. However, any such cleanup work should not
adversely affect the control systems for tailings piles that hc.ve already been
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PAGE 22
60 FR 2854, *2863
or are currently being installed
However, at three sites (Canonsburg, PA; Shiprock, NM; and Salt Lake City,
UT) the disposal design was based on standards remanded in part on September 3,
1985. We have considered these sites separately, based on information supplied
by DOE, and reached the tentative conclusion that modification of the existing
disposal cells is not warranted at any of them. Final determinations will be
made by DOE, with the concurrence of NRC.
The disposal site at Canonsburg, PA, is located above the banks of Chartiers
Creek. Contamination that might seep from the encapsulated tailings will reach
the surface within the site boundary, and is then diluted by water in the creek
to insignificant levels. Under these circumstances, this site qualifies for an
ACL under @ 192.02 (c) (3) (ii), and modification of the existing disposal cell is
not warranted.
The site at Shiprock, NM, which is located above the floodplain of the San
Juan River, is over an aquifer that may not be useful as a source of water for
drinking or other beneficial purpose because of its quality, areal extent, and
yield. Most of the groundwater in this aquifer appears to have originated from
seepage of tailings liquor from mill impoundments and not to be contributing to
contamination of any currently or potentially useful aquifer. Additionally, the
quality of this water may be degraded by uncontrolled disposal of municipal
refuse north and south of the site. DOE is currently in the process of
completing its characterization of this groundwater, and may or may not
recommend use of a supplemental standard under @ 192.21(g). In any case,
however, it appears unlikely that modification of the existing disposal cell
will be necessary.
The site containing the tailings from the Salt Lake City mill is located at
Clive, Utah, over groundwater that contains dissolved solids in excess of 10,000
mg/1 and is not contributing to contamination of any currently or potentially
useful aquifer. Under these circumstances, this site also qualifies for a
supplemental standard under ® 192.21 (g), and modification of the existing
disposal cell is not warranted.
-VI. Relationship to Other Policy and Requirements lln July 1991 EPA completed
development of a strategy to guide future EPA and State activities in
groundwater protection and cleanup. A key element of this strategy is a
statement of EPA Groundwater Protection Principles' nl that has as its overall
goals the prevention of adverse effects on human health and the environment and
protection of the environmental integrity of the nation's groundwater resources.
To achieve these [*2864] goals, EPA developed principles regarding
prevention; remediation; and Federal, State, and local responsibilities. These
principles are set forth and their implementation by this rule summarized below.
nl Protecting the Nation's Groundwater: EPA's Strategy for the 1990s, The
Final Report of the EPA Groundwater Task Force, U.S. Environmental Protection
Agency, Washington, (Report 21Z-1020), July 1991.
(1) With respect to prevention: groundwater should be protected to ensure
that the nation's currently used and reasonably expected drinking water
supplies, both public and private, do not present adverse health risks and are
preserved for present and future generations. Groundwater should also be
protected to ensure that groundwater that is closely hydrologically connected
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PA3E 23
60 FR 2854, *2864
- - -7 ,r~a~- waters does not interfere with the attainment of surface water
•2..al-ty standards, which is necessary Co protect the integrity of associated
ecosvstems Groundwater protection can be achieved through a variety of means
including pollution prevention programs; source controls; siting controls; the
designation of wellhead protection areas and future public wa.ter supply areas;
and the protection of aquifer recharge areas. Efforts to protect groundwater
must also consider the use, value, and vulnerability of the resource, as well as
social and economic values.
This rule for uranium mill tailings protects groundwater fcy requiring that
disposal piles be designed to avoid any new contamination of groundwater that
would threaten human health or the environment in the future. Water is scarce in
the Western States where these disposal sites occur. Currently almost half of
the water consumed in Arizona and New Mexico and 20 to 30 percent of the water
consumed in Utah, Colorado, Idaho, and Texas is groundwater. The population in
the Mountain States is expected to increase more than that of any other region
between now and the year 2010. In particular, the population in Colorado, New
Mexico, Arizona, and Utah is expected to increase dramaticall/. Thus, in order
to ensure that all currently used and reasonably expected drinking water
supplies near these sites, both public and private, are adequately protected for
use by present and future generations, these rules apply drinlcing water
standards to all potable groundwater. The rule also requires ;hat
hydrologically-connected aquifers and surface waters, including designated
wellhead protection areas and future public water supply areas, be identified
and protected, and that other beneficial uses of groundwater besides drinking be
identified and protected, including the integrity of associated ecosystems. In
this regard we note that DOE has not identified any critical aquatic habitats
that have been or could be adversely affected by contamination from these sites.
(2) With respect to remediation: groundwater remediation activities must be
prioritized to limit the risk of adverse effects to human health risks first and
then to restore currently used and reasonably expected sources; of drinking water
and groundwater closely hydrologically connected to surface Welters, whenever
such restorations are practicable and attainable.
Pursuant to our responsibilities under Section 102(b) of UMTRCA, EPA advised
DOE in 1979 concerning the criteria which should govern the order in which these
sites should be cleaned up. Those criteria specified, in essence, that sites
capable of affecting the health of human populations the most should be
remediated first. As a result DOE has divided the 24 sites into three levels of
priority, based on the populations affected. In order to facilitate
implementation of these principles, we have, in this rule, provided DOE with
flexibility to prioritize their cleanup activities so as to first minimize human
exposure, then restore reasonably expected drinking water sources, and finally
to clean up groundwater only when restoration is practicable and attainable.
This has been done by relaxing the requirements for cleanup of water:
(a) If it is not a current or potential source of drinking water (i.e., it
meets the definition of limited use),
(b) Where natural processes will achieve the standards and ;here is no
current or planned use,
(c) Where adverse environmental impact will occur, and (d) where cleanup is
technologically impracticable.
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PAGE 24
60 FR 2854, *2864
(3) With respect to Federal, State, and local responsibilities, the primary
responsibility for coordinating and implementing groundwater protection programs
has always been and should continue to be vested with the States. An effective
groundwater protection program should link Federal, State, and local activities
into a coherent and coordinated plan of action. EPA should continue to improve
coordination of groundwater protection efforts within the Agency and with other
Federal agencies with groundwater responsibilities.
In the case of the sites covered by these regulations, UMTRCA specifies a
primary role for Federal rather than State agencies. However, since these
regulations are modeled after existing RCRA regulations, this will serve to
insure coherence and coordination with similar prevention and remediation
actions by EPA, the States, and other Federal agencies. For example, the
concentration limits in groundwater for listed constituents at the sites covered
by this rule are the same as those specified for cleanup and disposal at RCRA
sites by EPA and the States and at uranium mill sites licensed by NRC.
Executive Order 12866
Under Executive Order 12866 (58 FR 51735; October 4, 1993), EPA must
determine whether a rule is "significant" and therefore subject to review by the
Office of Management and Budget (OMB) and the requirements of the Executive
Order. The Order defines "significant regulatory action" as one that is likely
to result in a rule that may:
(1) Have an annual effect on the economy of $ 100 million or more or
adversely effect in a material way the economy, a sector of the economy,
productivity, competition, jobs, the environment, public health or safety, or
State, local or tribal governments or communities;
(2) Create a serious inconsistency or otherwise interfere with an action
taken or planned by another agency;
(3) Materially alter the budgetary impact of entitlements, grants, user fees,
or loan programs or the rights and obligations of the recipients thereof; or
(4) Raise novel legal or policy issues arising out of legal mandates, the
President's priorities, or the principles set forth in the Executive Order.
Pursuant to the terms of Executive Order 12866, it has been determined that
this rule is may be a "significant regulatory action," because it may qualify
under criterion #4 above on the basis of comments submitted to EPA by letter on
January 15, 1993, as a result of OMB review under the previous Executive Order
12291. This action was therefore resubmitted to OMB for review. Comments from
OMB to EPA for their review under the previous Executive Order and EPA's
response to those comments are included in the docket. Any changes made in
response to OMB suggestions or recommendations as a result of the current review
will be documented in the public record.
Paperwork Reduction Act
Under the Paperwork Reduction Act of 1986, the Agency is required to state
the information collection requirements of any standard published on or after
July 1, 1988. In response to this requirement, this standard contains no
information collection requirements and imposes no reporting burden on the
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PAGE 2 5
60 FR 2854. *2864
List of Subjects in 40 CFR Part 192
Environmental protection, Groundwater, Radiation protection, Uranium.
[*2865j
Dated: December 14, 1994.
Carol M. Browner,
Administrator, Environmental Protection Agency.
For the reasons set forth in the preamble, 40 CFR part 192 is amended as
follows :
PART 192 --HEALTH AND ENVIRONMENTAL PROTECTION STANDARDS FOR URANIUM AND THORIUM
MILL TAILINGS
1. The authority citation for part 192 continues to read as follows:
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, Pub. L.
95-604, as amended.
Subpart A- -Standards for the Control of Residual Radioactive Materials From
Inactive Uranium Processing Sites
2 Section 192.01 is amended by revising paragraphs (a) and (e) and adding
paragraphs (g) through (r) to read as follows:
*,
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PAGE 26
60 FR 2854, *2865
(h) Administrator means the Administrator of the Environmental Protection
Agency
(i) Secretary means the Secretary of Energy.
(j) Commission means the Nuclear Regulatory Commission.
(k) Indian tribe means any tribe, band, clan, group, pueblo, or community of
Indians recognized as eligible for services provided by the Secretary of the
Interior to Indians.
(1) Processing site means:
(1) Any site, including the mill, designated by the Secretary under Section
102(a)(1) of the Act; and
(2) Any other real property or improvement thereon which is in the vicinity
of such site, and is determined by the Secretary, in consultation with the
Commission, to be contaminated "with residual radioactive materials derived from
such site.
(m) Tailings means the remaining portion of a metal-bearing ore after some or
all of such metal, such as uranium, has been extracted.
(n) Disposal period means the period of time beginning March 7, 1983 and
ending with the completion of all subpart A requirements specified under a plan
for remedial action except those specified in 0 192.03 and @ 192.04.
(o) Plan for remedial action means a written plan (or plans) for disposal and
cleanup of residual radioactive materials associated with a processing site that
incorporates the results of site characterization studies, environmental
assessments or impact statements, and engineering assessments so as to satisfy
the requirements of subparts A and B of this part. The plants) shall be
developed in accordance with the provisions of Section 108(a) of the Act with
the concurrence of the Commission and in consultation, as appropriate, with the
Indian Tribe and the Secretary of Interior.
(p) Post-disposal period means the period of time beginning immediately after
the disposal period and ending at termination of the monitoring period
established under @ 192.03.
(q) Groundwater means water below the ground surface in a zone of saturation.
(r) Underground source of drinking water means an aquifer or its portion:
(1)(i) Which supplies any public water system as defined in @ 141.2 of this
chapter; or
(ii) Which contains a sufficient quantity of groundwater to supply a public
water system; and
(A) Currently supplies drinking water for human consumption; or
(B) Contains fewer than 10,000 mg/1 total dissolved solids; and
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PAGE 21
60 FR 2854, "2865
(2) Which is not an exempted aquifer as defined in @ 144.7 of this chapter.
3 Section 192.02 is revised to read as follows:
@ 192.02 -- Standards.
Control of residual radioactive materials and their listed constituents shall
be designed nl to:
nl Because the standard applies to design, monitoring after disposal is not
required to demonstrate compliance with respect to @ 192.02 (a) and (b) .
(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 n2 release rate of 20 picocuries per square meter per
second, or
n2 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.
(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.
(c) Provide reasonable assurance of conformance with the following
groundwater protection provisions:
(1) The Secretary shall, on a site-specific basis, determine which of the
constituents listed in Appendix I to Part 192 are present in or reasonably
derived from residual radioactive materials and shall establish a monitoring
program adequate to determine background levels of each such constituent in
groundwater at each disposal site.
(2) The Secretary shall comply with conditions specified in a plan for
remedial action which includes engineering specifications for a system of
disposal designed to ensure that constituents identified under paragraph (c)(1)
of this section entering the groundwater from a depository site (or a processing
site, if residual radioactive materials are retained on the sate) will not
exceed the concentration limits established under paragraph (c:)(3) of this
section (or the supplemental standards established under ® 192.22) in the
uppermost aquifer underlying the site beyond the point of compliance established
under paragraph (c)(4) of this section.
(3) Concentration limits:
(i) Concentration limits shalj. be determined in the groundwater for listed
constituents identified under paragraph (c)(1) of this section. The
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PAGE 2 8
60 FR 2854, *2865
concentration of a listed constituent in groundwater must not exceed:
A, The background level of that constituent in the groundwater; or
(B! For any of the constituents listed in Table 1 to subpart A, the
respective value given in that Table if the background level of the constituent
is below the value given in the Table; or
(C) An alternate concentration limit established pursuant to paragraph
(c) (3! di) of this section.
di)(A) The Secretary may apply an alternate concentration limit if, after
[*2866] considering remedial or corrective actions to achieve the levels
specified in paragraphs (c)(3)(i)(A) and (B) of this section, he has determined
that the constituent will not pose a substantial present or potential hazard to
human health and the environment as long as the alternate concentration limit is
not exceeded, and the Commission has concurred.
(B) In considering the present or potential hazard to human health and the
environment of alternate concentration limits, the following factors shall be
considered:
(1) Potential adverse effects on groundwater quality, considering:
(i) The physical and chemical characteristics of constituents in the residual
radioactive material at the site, including their potential for migration;
(ii) The hydrogeological characteristics of the site and surrounding land;
(iii) The quantity of groundwater and the direction of groundwater flow;
(iv) The proximity and withdrawal rates of groundwater users;
(v) The current and future uses of groundwater in the region surrounding the
site;
(vi) The existing quality of groundwater, including other sources of
contamination and their cumulative impact on the groundwater quality;
(vii) The potential for health risks caused by human exposure to
constituents;
(viii) The potential damage to wildlife, crops, vegetation, and physical
structures caused by exposure to constituents;
(ix) The persistence and permanence of the potential adverse effects;
(x) The presence of underground sources of drinking water and exempted
aquifers identified under (8 144.7 of this chapter; and
(2) Potential adverse effects on hydraulically-connected surface-water
quality, considering:
(i) The volume and physical and chemical characteristics of the residual
radioactive material at the site;
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PAGE 2 9
60 FR 2854, *2966
in! The hydrogeological characteristics of the site and surrounding land;
(111) The quantity and quality of groundwater, and the direction of
groundwater flow;
(iv) The patterns of rainfall in the region;
(v) The proximity of the site to surface waters;
(vi) The current and future uses of surface waters in the region surrounding
the site and any water quality standards established for those surface waters;
(vn) The existing quality of surface water, including other sources of
contamination and their cumulative impact on surface water quality;
(viii) The potential for health risks caused by human exposure to
constituents;
(ix) The potential damage to wildlife, crops, vegetation, and physical
structures caused by exposure to constituents; and
(x) The persistence and permanence of the potential adverse effects.
(4i Point of compliance: The point of compliance is the location at which the
groundwater concentration limits of paragraph (c)(3) of this ssection apply. The
point of compliance is the intersection of a vertical plane w:.th the uppermost
aquifer underlying the site, located at the hydraulically downgradient limit of
the disposal area plus the area taken up by any liner, dike, or other barrier
designed to contain the residual radioactive material.
(d) Each site on which disposal occurs shall be designed and stabilized in a
manner that minimizes the need for future maintenance.
4. Section 192.03 is added to read as follows:
@ 192.03 -- Monitoring.
A groundwater monitoring plan shall be implemented, to be carried out over a
period of time commencing upon completion of remedial actions taken to comply
with the standards in @ 192.02, and of a duration which is adequate to
demonstrate that future performance of the system of disposal can reasonably be
expected to be in accordance with the design requirements of @ 192.02(c). This
plan and the length of the monitoring period shall be modified to incorporate
any corrective actions required under ® 192.04 or ® 192.12 (e).
5. Section 192.04 is added to read as follows:
@ 192.04 -- Corrective Action.
If the groundwater concentration limits established for disposal sites under
provisions of ® 192.02(c) are found or projected to be exceeded, a corrective
action program shall be placed into operation as soon as is practicable, and in
no evenc later than eighteen (18) months after a finding of exceedance. This
corrective action program will restore the performance of the system of disposal
to the original concentration limits established under @ 192.02 (c) (3), to the
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PAGE
60 FR 2854, *2866
extent reasonably achievable, and, in any case, as a minimum shall:
(a) Conform with the groundwater provisions of @ 192.02 (c) (3), and
(b) Clean up groundwater in conformance with subpart B, modified as
appropriate to apply to the disposal site.
6. Table 1 is added, to subpart A to read as follows:
Table 1 to Subpart A.--Maximum Concentration of
Constituents for Groundwater Protection
Constituent concentration fn 1
Arsenic C
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
Nitrate (as N)
Molybdenum
Combined radium-226 and radium-228
Combined uranium-234 and uranium-238 fn 2
Gross alpha-particle activity (excluding radon and uranium)
Endrin (1,2,3,4,10,10-hexachloro-6,7-exposy-
l,4,4a,5,6,7,8,8a-octahydro-l,4-endo,endo-5,8-
dimethanonaphthalene)
Lindane (1,2,3,4,5,6-hexachlorocyclohexane, gamma insomer)
Methoxychlor (1,1,l-trichloro-2,2'-bis(p-
methoxyphenylethane))
Toxaphene (C10H10C16, technical chlorinated catnphene, 67-69
percent chlorine)
2,4-D (2,4-dichlorophenoxyacetic acid)
2,4,5-TP Silvex (2,4,5-trichlorophenoxypropionic acid)
Maximum
. 05
1.0
0 . 01
0 .05
0.05
0.002
0.01
0 .05
10 .
0.1
5 pCi/liter
30 pCi/liter
15 pCi/liter
0.0002
0 .004
0.1
0 .005
0.1
0.01
fn 1 Milligrams per liter, unless stated otherwise.
fn 2 Where secular equilibrium obtains, this criterion will be satisfied by a
concentration of 0.044 milligrams per liter (0.044 mg/1). For conditions of
other than secular equilibrium, a corresponding value may be derived and
applied, based on the measured site-specific ratio of the two isotopes of
uranium.
Subpart B--Standards for Cleanup of Land and Buildings Contaminated with
Residual Radioactive Materials from Inactive Uranium Processing Sites
7. Section 192.11 is amended by revising paragraph (a) and adding paragraph
(e) to read as follows:
192.11 -- Definitions.
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PAGE 31
SO FR 2854, *2866
•a) Unless otherwise indicated in this subpart, all terms shall have the same
meaning as defined in subpart A.
[*2867]
(e) Limited use groundwater means groundwater that is not a current or
potential source of drinking water because (1) the concentration of total
dissolved solids is in excess of 10,000 mg/1, or (2) widespread, ambient
contamination not due to activities involving residual radioactive materials
from a designated processing site exists that cannot be cleaned up using
treatment methods reasonably employed in public water systems, or (3) the
quantity of water reasonably available for sustained continuous use is less than
150 gallons per day. The parameters for determining the quantity of water
reasonably available shall be determined by the Secretary with the concurrence
of the Commission.
8. In @ 192.12, the introductory text is republished without change and
paragraph (c) is added to read as follows:
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:
(c) The Secretary shall comply with conditions specified in a plan for
remedial action which provides that contamination of groundwater by listed
constituents from residual radioactive material at any designated processing
site (® 192,01(1)) shall be brought into compliance as promptly as is reasonably
achievable with the provisions of ® 192.02 (c) (3) or any supplemental standards
established under @ 192.22. For the purposes of this subpart:
(1) A monitoring program shall be carried out that is adequate to define
backgroundwater quality and the areal extent and magnitude of ojroundwater
contamination by listed constituents from residual radioactive materials (@
192.02 (c) {!)) and to monitor compliance with this subpart. The Secretary shall
determine which of the constituents listed in Appendix I to part 192 are present
in or could reasonably be derived from residual radioactive material at the
site, and concentration limits shall be established in accordance with @
192.02 (c) (3)
(2) (i) If the Secretary determines that sole reliance on active remedial
procedures is not appropriate and that cleanup of the groundwater can be more
reasonably accomplished in full or in part through natural flushing, then the
period for remedial procedures may be extended. Such an extended period may
extend to a term not to exceed 100 years if:
(A) The concentration limits established under this subpart are projected to
be satisfied at the end of this extended period,
(B) Institutional control, having a high degree of permanence and which will
effectively protect public health and the environment and satisfy beneficial
uses of groundwater during the extended period and which is enforceable by the
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PAGE 32
60 FR 2854, *2867
administrative or judicial branches of government entities, is instituted and
maintained, as part of the remedial action, at the processing site and wherever
contamination by listed constituents from residual radioactive materials is
found in groundwater, or is projected to be found, and
(C) The groundwater is not currently and is not now projected to become a
source for a public water system subject to provisions of the Safe Drinking
Water Act during the extended period.
(ii) Remedial actions on groundwater conducted under this subpart may occur
before or after actions under Section 104 (f) (2.) of the Act are initiated.
(3) Compliance with this subpart shall be demonstrated through the monitoring
program established under paragraph (c)(1) of this section at those locations
not beneath a disposal site and its cover where groundwater contains listed
constituents from residual radioactive material.
Subpart C-- Implementation
9. In @ 192.20, paragraphs (a)(2) and (a)(3) and the first sentence of
paragraph (b)(1) are revised and paragraphs (a)(4) and (b)(4) are added to read
as follows:
192.20 -- Guidance for implementation.
* * * + *
(a) (1) * * *
(2) 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 or other appropriately located wells. The
groundwater monitoring list in Appendix IX of part 264 of this chapter (plus the
additional constituents in Table A of this paragraph) may be used for screening
purposes in place of Appendix I of part 192 in the monitoring program. New
depository sites for tailings that contain water at greater than the level of
"specific retention" should use aliner or equivalent. In considering design
objectives for groundwater protection, the implementing agencies should give
priority to concentration levels in the order listed under @ 192.02 (c) (3) (i) .
When considering the potential for health risks caused by human exposure to
known or suspected carcinogens, alternate concentration limits pursuant to
paragraph 192.02 (c) (3) (ii) should be established at concentration levels which
represent an excess lifetime risk, at a point of exposure, to an average
individual no greater than between 10-4 and 10-6.
Table A to @ 192.20 (a) (2)--Additional Listed Constituents
Nitrate (as N)
Molybdenum
Combined radium-226 and radium-228
Combined uranium-234 and uranium-238
Gross alpha-particle activity (excluding radon and uranium)
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PAGE 3 3
6C FR 2854, *2867
i3/ The plan for remedial action, concurred in by the Commission, will
specify how applicable requirements of subpart A are to be satisfied. The plan
should include the schedule and steps necessary to complete disposal operations
at the site. It should include an estimate of the inventory of wastes to be
disposed of in the pile and their listed constituents and address any need to
eliminate free liquids; stabilization of the wastes to a bearing capacity
sufficient to support the final cover; and the design and engineering
specifications for a cover to manage the migration of liquids, through the
stabilized pile, function without maintenance, promote drainage and minimize
erosion or abrasion of the cover, and accommodate settling and subsidence so
that cover integrity is maintained. Evaluation of proposed designs to conform to
subpart A should be based on realistic technical judgments and include use of
available empirical information. The consideration of possible failure modes and
related corrective actions should be limited to reasonable failure assumptions,
with a demonstration that the disposal design is generally amenable to a range
of corrective actions.
(4) The groundwater monitoring list in Appendix IX of part 264 of this
chapter (plus the additional constituents in Table A in paragraph (a)(2) of this
section) may be used for screening purposes in place of Appendix I of part 192
in monitoring programs. The monitoring plan required under ® '192.03 should be
designed to include verification of site-specific assumptions used to project
the performance of the disposal system. Prevention of [*286ii] contamination
of groundwater may be assessed by indirect methods, such as measuring the
migration of moisture in the various components of the cover, the tailings, and
the area between the tailings and the nearest aquifer, as well as by direct
monitoring of groundwater. In the case of vicinity properties (® 192.01(1) (2)),
such assessments may not be necessary, as determined by the Secretary, with the
concurrence of the Commission, considering such factors as local geology and the
amount of contamination present. Temporary excursions from applicable limits of
groundwater concentrations that are attributable to a disposal operation itself
shall not constitute a basis for considering corrective action under @ 192.04
during the disposal period, unless the disposal operation is suspended prior to
completion for other than seasonal reasons.
(b) (1) Compliance with ® 192.12 (a) and (b) of subpart B, to the extent
practical, should be demonstrated through radiation surveys. * * *
(4) The plants) for remedial action will specify how applicable requirements
of subpart B would be satisfied. The plan should include the schedule and steps
necessary to complete the cleanup of groundwater at the site. 'It should document
the extent of contamination due to releases prior to final disposal, including
the identification and location of listed constituents and the rate and
direction of movement of contaminated groundwater, based upon t.he monitoring
carried out under ® 192.12 (c) (1). In addition, the assessment sihould consider
future plume movement, including an evaluation of such processes as attenuation
and dilution and future contamination from beneath a disposal site. Monitoring
for assessment and compliance purposes should be sufficient to establish the
extent and magnitude of contamination, with reasonable assurance, through use of
a carefully chosen minimal number of sampling locations. The location and number
of monitoring wells, the frequency and duration of monitoring, and the selection
of indicator analytes for long-term groundwater monitoring, and, more generally,
the design and operation of the monitoring system, will depend on the
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PAGE 34
60 FR 2854, *2868
potential for risk to receptors and upon other factors, including
characteristics of the subsurface environment, such as velocity of groundwater
flow, contaminant retardation, time of groundwater or contaminant transit to
receptors, results of statistical evaluations of data trends, and modeling of
the dynamics of the groundwater system. All of these factors should be
incorporated into the design of a site-specific monitoring program that will
achieve the purpose of the regulations in this subpart in the most
cost-effective manner. In the case of vicinity properties (@ 192.01(1) (2)), such
assessments will usually not be necessary. The Secretary, with the concurrence
of the Commission, may consider such factors as local geology and amount of
contamination present in determining criteria to decide when such assessments
are needed. In cases where @ 192.12 (c) (2) is invoked, the plan should include a
monitoring program sufficient to verify projections of plume movement and
attenuation periodically during the extended cleanup period. Finally, the plan
should specify details of the method to be used for cleanup of groundwater.
-10. In ® 192.21, the introductory text and paragraph (b) are revised,
paragraph (f) is redesignated as paragraph (h), and new paragraphs (f) and (g)
are added to read as follows:
@ 192.21 -- Criteria for applying supplemental standards
Unless otherwise indicated in this subpart, all terms shall have the same
meaning as defined in Title I of the Act or in subparts A and B. The
implementing agencies may (and in the case of paragraph (h) of this section
shall) apply standards under @ 192.22 in lieu of the standards of subparts A or
B if they determine that any of the following circumstances exists:
(b) Remedial actions to satisfy the cleanup standards for land, @ 192.12 (a),
and groundwater, ® 192.12 (c), or the acquisition of minimum materials required
for control to satisfy @@ 192.02 (b) and (c), would, notwithstanding reasonable
measures to limit damage, directly produce health and environmental harm that is
clearly excessive compared to the health and environmental benefits, now or in
the future. A clear excess of health and environmental harm is harm that is
long-term, manifest, and grossly disproportionate to health and environmental
benefits that may reasonably be anticipated.
*****
(f) The restoration of groundwater quality at any designated processing site
under ® 192.12(c) is technically impracticable from an engineering perspective.
(g) The groundwater meets the criteria of ® 192.11(e).
*****
11. In ® 192.22, paragraphs (a) and (b) are revised and paragraph (d) is
added to read as follows:
192.22 -- Supplemental standards.
*****
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PAGE 35
60 FR 2854, *28S8
i'a! When one or more of che criteria of ® 192.21(a) through (g) applies, the
Secretary shall select and perform that alternative remedial action that comes
as close to meeting the otherwise applicable standard under @ 192.02 (c) (3) as is
reasonably achievable.
t» When ® 192.21 (h) applies, remedial actions shall reduce other residual
radioactivity to levels that are as low as is reasonably achievable and conform
to the standards of subparts A and B to the maximum extent practicable.
(d) When @ 192.21(b), (f), or (g) apply, implementing agencies shall apply
any remedial actions for the restoration of contamination of groundwater by
residual radioactive materials that is required to assure, at a minimum,
protection of human health and the environment. In addition, when @ 192.21(g)
applies, supplemental standards shall ensure that current and reasonably
projected uses of the affected groundwater are preserved.
12. Appendix I is added to part 192 to read as follows:
Appendix I to Part 192--Listed Constituents
Acetonitrile
Acetophenone (Ethanone, 1-phenyl)
2-Acetylaminofluorene (Acetamide, N-9H-fluoren-2-yl-)
Acetyl chloride
l-Acetyl-2-thiourea (Acetamide, N-(aminothioxymethyl)-)
Acrolein (2-Propenal)
Acrylamide (2-Propenamide)
Acrylonitrile (2-Propenenitrile)
Af latoxins
Aldicarb (Propenal, 2-methyl-2-(methylthio)-,0-[(methylatnino)carbonyl]oxime
Aldrin (1,4:5,8-Dimethanonaphthalene,
1,2, 3, 4,10,10-hexachloro-l,4,4a,5,8,8a-hexahydro(l alpha ,4 alpha ,4a beta ,5
alpha,8 alpha,8 alpha beta)-)
Allyl alcohol (2-Propen-l-ol)
Allyl chloride (1-Propane,3-chloro)
Aluminum phosphide
4-Aminobiphenyl ([!,!'-Biphenyl]-4-amine)
5-(Aminomethyl)-3-isoxazolol (3(2H)-Isoxazolone,5-(aminomethyl)-)
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60 FR 2854, *2868
4-Aminopyridine (4 -Pyridineamine)
Amitrole flH-1.2.4-Triazol- 3-amine)
Ammonium vanadate (Vanadic acid, ammonium salt)
Aniline (Benzenamine)
Antimony and compounds, N.O.S. nl
nl The abbreviation N.O.S. (not otherwise specified) signifies those members
of the general class not specifically listed by name in this appendix.
[*2869]
Aramite (Sulfurous acid, 2-chloroethyl
2-(4-(1,1-dimethylethyl)phenoxy]-1-methylethyl ester)
Arsenic-and compounds, N.O.S.
Arsenic acid (Arsenic acid H sub 3AsO sub 4)
Arsenic pentoxide (Arsenic oxide As sub 20 sub 5)
Auramine (Benzamine, 4,4'-carbonimidoylbis[N,N-dimethyl-])
Azaserine (L-Serine, diazoacetate (ester))
Barium and compounds, N.O.S.
Barium cyanide
Benz[c]acridine (3,4-Benzacridine)
Benz[a]anthracene (1,2-Benzanthracene)
Benzal chloride (Benzene, dichloromethyl-)
t Benzene (Cyclohexatriene)
Benzenearsonic acid (Arsenic aci,d, phenyl-)
Benzidine ([1,1'-Biphenyl]-4,4'-diamine)
Benzo[b]fluoranthene (Benz[e]acephananthrylene)
Benzo[j]fluoranthene
Benzo[k]fluoranthene
Benzo[a]pyrene
p-Benzoquinone (2,5-Cyclohexadiene-l,4-dione)
Benzotrichloride (Benzene, (trichloro-
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60FR2854,*2869
metr.yl i -,
Benzyl chloride "Benzene, (chloromethyl)-)
Beryl IIUTI and compounds, N.O.S.
Bromoacetone ' 2 - Propanone, 1-bromo-)
Bromoform (Methane, tribromo-)
4-Bromophenyl phenyl ether (Benzene, l-bromo-4-phenoxy-)
Brucine (Strychnidin-10-one, 2,3-dimeth-
oxy-)
Butyl benzyl phthalate (1,2-Benzenedicarbozylic acid, butyl phenylmethyl ester)
Cacodylic acid (Arsinic acid, dimethyl)
Cadmium and compounds, N.O.S.
Calcium chromate (Chromic acid H sub 2CrO sub 4, calcium salt!
Calcium cyanide (Ca(CN) sub 2)
Carbon disulfide
Carbon oxyfluoride (Carbonic difluoride)
Carbon tetrachloride (Methane, tetrachloro-)
Chloral (Acetaldehyde, trichloro-)
Chlorambucil (Benzenebutanoic acid, 4-[bis(2-chloroethyl)amino]-)
Chlordane
(4,7-Methano-lH-indene,1,2,4,5,6,7,8,8-octachloro-2,3,3a,4,7,7a-hexahydro-)
Chlorinated benzenes, N.O.S.
Chlorinated ethane, N.O.S.
Chlorinated fluorocarbons, N.O.S.
Chlorinated naphthalene, N.O.S.
Chlorinated phenol, N.O.S.
Chlornaphazin (Naphthalenamine, N,N'-bis(2-chlorethyl)-)
Chloroacetaldehyde (Acetaldehyde, chloro-)
Chloroalkyl ethers, N.O.S.
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60 FR 2854, *2869
p-Chloroaniline (Benzenamine, 4-chloro-l
Chlorocenzene (Benzene, chloro-)
Chlorobenzilate (Benzeneacetic acid, 4-chloro- alpha -(4-chlorophenyl)- alpha
-hydroxy-, ethyl ester)
p-Chloro-m-cresol (Phenol, 4-chloro-3-methyl)
2-Chloroethyl vinyl ether (Ethene, (2-chloroethoxy)-)
Chloroform (Methane, trichloro-)
Chloromethyl methyl ether (Methane, chloromethoxy-)
beta -Chloronapthalene (Naphthalene, 2-chloro-)
o-Chlorophenol (Phenol, 2-chloro-)
1-(o-Chlorophenyl)thiourea (Thiourea, (2-chlorophenyl-))
3-Chloropropionitrile (Propanenitrile, 3-chloro-)
Chromium and compounds, N.O.S.
Chrysene
Citrus red No. 2 (2-Naphthalenol, 1-[(2,5-dimethoxyphenyl)azo]-)
Coal tar creosote
Copper cyanide (CuCN)
Creosote
Cresol (Chresylic acid) (Phenol, methyl-)
Crotonaldehyde (2-Butenal)
Cyanides (soluble salts and complexes), N.O.S.
Cyanogen (Ethanedinitrile)
Cyanogen bromide ((CN)Br)
Cyanogen chloride ((CN)C1)
Cycasin (beta-D-Glucopyranoside, (methyl-ONN-azoxy)methyl)
2-Cyclohexyl-4,6-dinitrophenol (Phenol, 2-cyclohexyl-4,6-dinitro-)
Cyclophosphamide (2H-1,3,2-Oxazaphosphorin-2-amine,N,N-bis(2-chloroethyl)
tetrahydro-,2-oxide)
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50 FR 2854, *2869
2,4-3 and salts and esters (Acetic acid, (2,4-dichlorophencxy)-)
Daunomycin (5,12-Naphthacenedione,8-acetyl-10-[(3-amino-2,3,6-trideoxy- alpha
-Llyxo-hexopyranosyl)oxy]-7,8,9,10-tetrahydro-6,8,11-trihydroxy-1-methoxy-, ( 8S-
cis • '
ODD (Benzene, 1,1'-(2,2-dichloroethylidene)bis[4-chloro-)
DDE (Benzene, 1,1-(dichloroethylidene)bis[4-chloro-)
DDT (Benzene, 1,1'-(2,2,2-trichloroethlyidene)bis[4-chloro-)
Diallate (Carbomothioic acid, bis(1-methylethyl)-,S-(2,3-dichloro-2-propenyl)
ester)
Dibenz[a,h]acridine
Dibenz[a,j]acridine
Dibenz[a,h]anthracene
7H-Dibenzo[c,g]carbazole
Dibenzo[a,e]pyrene (Naphtho[1,2,4,5-def)crysene)
Dibenzo[a,h]pyrene (Dibenzo[b,def]crysene)
Oxbenzo[a,±]pyrene (Benzo[rst]pentaphene)
1,2-Dibromo-3-chloropropane (Propane, 1,2-dibromo-3-chloro-)
Dibutylphthalate (1,2-Benzenedicarboxylic acid, dibutyl ester)
o-Dichlorobenzene (Benzene, 1,2-dichloro-)
m-Dichlorobenzene (Benzene, 1,3-dichloro-)
p-Dichlorobenzene (Benzene, 1,4-dichloro-)
Dichlorobenzene, N.O.S. (Benzene; dichloro-, N.O.S.)
3,3'-Dichlorobenzidine ([!,!'-Biphenyl]-4,4'-diamine, 3,3'-dichloro-)
l,4-Dichloro-2-butene (2-Butene, 1,4-dichloro-)
Dichlorodifluoromethane (Methane, dichlorodifluoro-)
Dichloroethylene, N.O.S.
1,1-Dichloroethylene (Ethene, 1,1-dichloro-)
1,2-Dichloroethylene (Ethene, 1,2-dichloro-,(E)-)
Dichloroethyl ether (Ethane, 1,1'-oxybis[2-chloro-)
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60 FR 2854, *2869
Dichloroisopropyl ether (Propane, 2,2'-oxybis [2-chloro-)
Dichloromechoxy ethane (Ethane, 1,1'-[methylenebis(oxy)bis[2-chloro-)
Dichloromethyl ether (Methane, oxybis[chloro-}
2,4-Dichlorophenol (Phenol, 2,4-dichloro-)
2,6-Dichlorophenol (Phenol, 2,6-dichloro-)
Dichlorophenylarsine (Arsinous dichloride, phenyl-)
Dichloropropane, N.O.S. (Propane,
dichloro-,)
Dichloropropanol, N.O.S. (Propanol, dichloro-,)
Dichloropropene; N.O.S. (1-Propane, dichloro-,)
1,3-Dichloropropene (1-Propene, 1,3-dichloro-)
Dieldrin
(2,7:3,6-Dimethanonaphth[2,3-b]oxirene,3,4,5,6,9,9-hexachloro-la,2,2a,3,6,6a,
7,7a,octahydro-,(la alpha ,2 beta ,2a alpha ,3 beta ,6 beta ,6a alpha ,7 beta
,7a alpha)-)
1,2:3,4-Diepoxybutane (2,2'-Bioxirane)
Diethylarsine (Arsine, diethyl-)
1,4 Diethylene oxide (1,4-Dioxane)
Diethylhexyl phthalate (1,2-Benzenedicarboxlyic acid, bis(2-ethylhexl) ester)
N,N-Diethylhydrazine (Hydrazine, 1,2-diethyl)
0,0-Diethyl S-methyl dithiophosphate (Phosphorodithioic acid, 0,0-diethyl
S-methyl ester)
Diethyl-p-nitrophenyl phosphate (Phosphoric acid, diethyl 4-nitrophenyl ester)
Diethyl phthalate (1,2-Benzenedicarboxylic acid, diethyl ester)
O,O-Diethyl O-pyrazinyl phosphorothioate (Phosphorothioic acid, O,O-diethyl
0-pyrazinyl ester)
Diethylstilbesterol (Phenol, 4,4'-(1,2-diethyl-l,2-ethenediyl)bis-,(E)-)
Dihydrosafrole (1,3-Benxodioxole, 5-propyl-)
Diisopropylfluorophosphate (DFP) (Phosphorofluoridic acid, bis(l-methyl ethyl)
ester)
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SO FR 2854, *2869
Diraethoate (Phosphorodithioic acid, 0,0-dimethyl S-[2-(methyl ammo) 2-oxoethyl]
ester)
3,3'-Dimethoxybenzidine ([1,1'-Biphenyl]-4,4'-diamine, 3,3'-dimethoxy-)
p-Dimethylaminoazobenzene (Benzenamine, N,N-dimethyl-4 -(pherrylazo)-)
7,12-Dimethylbenz[a]anthracene (Benz[a]anthracene, 7,12-dimethyl-)
3,3'-Dimethylbenzidine ([!,!'-Biphenyl]-4,4'-diamine, 3,3'-dimethyl-)
Dimethylcarbamoyl chloride (carbamic chloride, dimethyl-)
1,1-Dimethylhydrazine (Hydrazine, 1,1-dimethyl-)
1,2-Dimethylhydrazine (Hydrazine, 1,2-dimethyl-)
alpha , alpha -Dlmethylphenethylamine (Benzeneethanamine, alpha , alpha
-dimethyl-)
2,4-Dimethylphenol (Phenol, 2,4-dimethyl-)
Dimethylphthalate (1,2-Benzenedicarboxylic acid, dimethyl ester)
Dimethyl sulfate (Sulfuric acid, dimethyl ester)
Dinitrobenzene, N.O.S. (Benzene, dinitro-)
4 , 6-Dinitro-o-cresol and salts (Phenol, 2-methyl-4,6-dinitro-)
2,4-Dinitrophenol (Phenol, 2,4-dinitro-)
2,4-Dinitrotoluene (Benzene, l-methyl-2,4-dinitro-)
2,6-Dinitrotoluene (Benzene, 2-methyl-l,3-dinitro-)
Dinoseb (Phenol, 2-(1-methylpropyl)-4,6-dinitro-)
Di-n-octyl phthalate (1,2-Benzenedicarboxylic acid, dioctyl ester)
1,4-Dioxane (1,4-Diethyleneoxide)
Diphenylamine (Benzenaraine, N-phenyl-) [*2870]
1,2-Diphenylhydrazine (Hydrazine, 1,2-diphenyl-)
Di-n-propylnitrosamine (l-Propanamine,N-nitroso-N-propyl-)
Disulfoton (Phosphorodithioic acid, 0,0-diethyl S-[2-(ethylthio)ethyl] ester)
Dithiobiuret (Thioimidodicarbonic diamide [ (H sub 2N)C(S)] sub 2NH)
Endosulfan (6,9,Methane-2,4,3-benzodioxathiepin,6,7,8,9,10,10-hexachloro-l,5,5a,
S,9,9ahexahydro,3-oxide)
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60 FR 2854, *2870
Endothall (7-Oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid)
Endrin and metabolites
(2,7.3,6-Dimethanonaphth[2,3-b]oxirene,3,4,5,6,9,9-hexachlorola,2,2a,3,6,6a,7,7a
-octa-hydro,(la alpha ,2 beta ,2a beta ,3 alpha ,6 alpha ,6a beta ,7 beta ,7a
alpha)-;
Epichlorohydrin (Oxirahe, (chloromethyl)-)
Epinephrine (1, 2-Benzenediol,4-[l-hydroxy-2-(methylamino)ethyl] -, (R)-,)
Ethyl carbamate (urethane) (Carbamic acid, ethyl ester)
Ethyl cyanide (propanenitrile)
Ethylenebisdithiocarbamic acid, salts and esters (Carbamodithioic acid,
1,2-Ethanediylbis-)
Ethylene dibromide (1,2-Dibromoethane)
Ethylene dichloride (1,2-Dichloroethane)
Ethylene glycol monoethyl ether (Ethanol, 2-ethoxy-)
Ethyleneimine (Aziridine)
Ethylene oxide (Oxirane)
Ethylenethiourea (2-Imidazolidinethione)
Ethylidene dichloride (Ethane, 1,1-
Dichloro-)
Ethyl methacrylate (2-Propenoic acid, 2-methyl-, ethyl ester)
Ethylmethane sulfonate (Methanesulfonic acid, ethyl ester)
Famphur (Phosphorothioic acid, 0-[4-[(dimethylamino)sulphonyl]phenyl]
0,0-dimethyl ester)
Fluoranthene .
Fluorine
Fluoroacetamide (Acetamide, 2-fluoro-)
Fluoroacetic acid, sodium salt (Acetic acid, fluoro-, sodium salt)
Formaldehyde (Methylene oxide)
Formic acid (Methanoic acid)
Glycidylaldehyde (Oxiranecarboxyaldehyde)
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60 FR 28S4, *2870
Halomethane, N.O.S.
Heptachlor (4, 7-Methano-lH-indene,
1,4,5,6,7,8,8-heptachloro-3a,4,7,7a-tetrahydro-)
Heptachlor epoxide ( alpha , beta , and gamma isomers)
(2,5-Mechano-2H-indeno[1,2-b]-oxirene,
2,3,4,5,6,7,7-heptachloro-la,Ib,5,5a,6,6a-hexa-hydro-,(la alpha ,Ib beta ,2
alpha ,5 alpha ,5a beta ,6 beta ,6a alpha)-)
Hexachlorobenzene (Benzene, hexachloro-)
Hexachlorobutadiene (1,3-Butadiene, 1,1,2,3,4,4-hexachloro-)
Hexachlorocyclopentadiene (1,3-Cyclopentadiene, 1,2,3,4,5,5-hexachloro-)
Hexachlorodibenzofurans
Heptachlorodibenzo-p-dioxins
Hexachloroechane (Ethane, hexachloro-)
Hexachlorophene (phenol, 2,2'-Methylenebis[3,4,6-trichloro-)
Hexachloropropene (1-Propene, 1,1,2,3,3,3-hexachloro-)
Hexaethyl tetraphosphate (Tetraphosphoric acid, hexaethyl este.r)
Hydrazine
Hydrocyanic acid
Hydrofluoric acid
Hydrogen sulfide (H sub 2S)
Indeno(1,2,3-cd)pyrene
Isobutyl alcohol (1-Propanol, 2-methyl-)
Isodrin (1,4,5,8-Dimethanonaphthalene,
1,2,3, 4,10,10-hexachloro-l,4,4a,5,8,8a-hexahydro, (1 alpha ,4 alpha ,4a beta ,5
beta ,8 beta ,8a beta)-)
Isosafrole (1,3-Benzodioxole, 5-(1-propenyl)-)
Kepone (1,3,4-Metheno-2H-cyclobuta[cd]pentalen-2-one,
l,la,3,3a,4,5,5,5a,5b,6-decachlorooctahydro-)
LasiocarpLne (2-Butenoic acid,
2-methyl-,7-[[2,3-dihydroxy-2-(1-methoxyethyl)-3-methyl-l-oxobutoxy]methyl]-
2,3,5,7a-tetrahydro-lH-pyrrolizin-l-yl ester)
Lead and compounds, N.O.S.
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60 FR 2854. *2870
Lead acetate (Acetic acid, lead(2+) salt)
Lead phosphate (Phosphoric acid, lead(2*) salt(2:3))
Lead subacetate (Lead, bis (acetato-0)tetrahydroxytri-)
Lindane (Clohexane, 1, 2,3,4,5,6-hexachloro-, (1 alpha ,2 alpha ,3 beta ,4 alpha
,5 alpha ,6 beta)-)
Maleic anhydride (2,5-Furandione)
Maleic hydrazide (3,6-Pyridazinedione, 1,2-dihydro-)
Malononitnle (Propanedinitrile)
Melphalan (L-Phenylalanine, 4-[bis(2-chloroethyl)aminol]-)
Mercury and compounds, N.0.S.
Mercury fulminate (Fulminic acid, mercury(2+) salt)
Methacrylonitrile (2-Propenenitrile, 2-methyl-)
Methapyrilene (1,2-Ethanediamine,
N,N-dimethyl-N'-2-pyridinyl-N'-(2-thienylmethyl)-)
Metholmyl (Ethamidothioic acid, N-[[(methylamino)carbonyl]oxy]thio-, methyl
ester)
Methoxychlor (Benzene, 1,1'-(2,2,2-trichloroethylidene)bis[4-methoxy-)
Methyl bromide (Methane, bromo-)
Methyl chloride (Methane, chloro-)
Methyl chlorocarbonate (Carbonchloridic acid, methyl ester)
Methyl chloroform (Ethane, 1,1,1-trichloro-)
3-Methylcholanthrene (Benz[j]aceanthrylene, 1,2-dihydro-3-methyl -)
4,4'-Methylenebis(2-chloroaniline) (Benzenamine, 4,4'-methylenebis(2-
chloro-)
Methylene bromide (Methane, dibromo-)
Methylene chloride (Methane, dichloro-)
Methyl ethyl ketone (MEK) (2-Butanone)
Methyl ethyl ketone peroxide (2-Butanone, peroxide)
Methyl hydrazine (Hydrazine, methyl-)
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60 FR 2854, *2870
Methyl iodide (Methane, iodo-1
Methyl isocyanate (Methane, isocyanato-)
2-Methyllactonitrile (Propanenitrile, 2-hydroxy-2-methyl-)
Methyl methacrylate (2-Propenoic acid, 2-methyl-, methyl ester)
Methyl methanesulfonate (Methanesulfonic acid, methyl ester)
Methyl parathion (Phosphorothioic acid, 0,0-dimethyl O-(4-nitrophenyl) ester)
Methylthiouracil (4(1H)Pyrimidinone, 2,3-dihydro-6-methyl-2-thioxo-)
Mitomycin C
iAzirino[2',3':3,4]pyrrolo [1,2-a]indole-4,7-dione,6-amino-8-[[(aminocarbonyl)
oxy]methyl]-1,la,2,8,8a,8b-hexahydro-8a-methoxy-5-methy-, [laS-(la alpha ,8 beta
,8a alpha ,8b alpha)]-)
MNNG (Guanidine, N-methyl-N'-nitro-N-nitroso-)
Mustard gas (Ethane, 1,1'-thiobis[2-chloro-)
Naphthalene
1,4-Naphthoquinone (1,4-Naphthalenedione)
alpha -Naphthalenamine . (1-Naphthylamine)
beta -Naphthalenamine (2-Naphthylamine)
alpha -Naphthylthiourea (Thiourea, 1-naphthalenyl-)
Nickel and compounds, N.O.S.
Nickel carbonyl (Ni(CO) sub 4 (T-4)-)
Nickel cyanide (Ni(CN) sub 2)
Nicotine and salts (Pyridine, 3 -(l-methyl-2-pyrrolidinyl)-, (S)-)
Nitric oxide (Nitrogen oxide NO)
p-Nitroaniline (Benzenamine, 4-nitro-)
Nitrobenzene (Benzene, nitro-)
Nitrogen dioxide (Nitrogen oxide NO sub 2)
Nitrogen mustard, and hydrochloride salt (Ethanamine,
2-chloro-N-(2-chloroethyl)-N-methyl-)
Nitrogen mustard N-oxide and hydrochloride salt (Ethanamine,
2chloro-N-(2-chloroethyl)N-methyl-, N-oxide)
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60 FR 2854, *2870
Nitroglycerin (1,2,3-Propanetriol, trinitrate)
p-Nitrophenol (Phenol, 4-nitro-)
2-Nitropropane (Propane, 2-nitro-)
Nitrosamines, N.O.S.
N-Nitrosodi-n-butylamine (1-Butanamine, N-butyl-N-nitroso-)
N-Nitrosodiethanolamine (Ethanol, 2,2'-(nitrosoimino)bis-)
N-Nitrosodiethylamine (Ethanamine, N-ethyl-N-nitroso-l)
N-Nitrosodimethylamine (Methanamine, N-methyl-N-nitroso-)
N-Nitroso-N-ethylurea (Urea, N-ethyl-N-nitroso-)
N-Nitrosomethylethylamine (Ethanamine, N-methyl-N-nitroso-)
N-Nitroso-N-methylurea (Urea, N-methyl-N-nitroso-)
N-Nitroso-N-methylurethane (Carbamic acid, methylnitroso-, ethyl ester)
N-Nitrosomethylvinylamine (Vinylamine, N-methyl-N-nitroso-)
N-Nitrosomorpholine (Morpholine,
4-nitroso-)
N-Nitrosonornicotine (Pyridine, 3-(l-nitroso-2-pyrrolidinyl)-, (S)-)
N-Nitrosopiperidine (Piperidine, 1-nitroso-)
Nitrosopyrrolidine (Pyrrolidine, l-nitroso-)
N-Nitrososarcosine (Glycine, N-methyl-N-nitroso-)
5-Nitro-o-toluidine (Benzenamine, 2-methyl-5-nitro-)
Octamethylpyrophosphoramide (Diphosphoramide, octamethyl-)
Osmium tetroxide (Osmium oxide OsO sub 4, (T-4)-)
Paraldehyde (1,3,5-Trioxane, 2,4,6-tri
methyl-)
Parathion (Phosphorothioic acid, O,0-diethyl 0-(4-nitrophenyl) ester)
Pentachlorobenzene (Benzene, pentachloro-)
Pentachlorodibenzo-p-dioxins
Pentachlorodibenzofurans
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60 FR 2854, *2870
Pentachloroethane (Ethane, pentachloro-)
Pencachloromtrobenzene (PCNB) (Benzene, pentachloronitro-)
Pentachlorophenol (Phenol, pentachloro-)
Phenacetin (Acetamide, N-(4-ethoxyphenyl)-)
Phenol
Phenylenediamine (Benzenediamine)
Phenylmercury acetate (Mercury, (acetato-0) phenyl-) [*2871.|
Phenylthiourea (Thiourea, phenyl-)
Phosgene (Carbonic dichloride)
Phosphine
Phorate (Phosphorodithioic acid, 0,0-diethyl S-((ethylthiomethyl] ester)
Phthalic acid esters, N.O.S.
Phthalic anhydride (1,3-isobenzofurandione)
2-Picoline (Pyridine, 2-methyl-)
Polychlorinated biphenyls, N.O.S.
Potassium cyanide (K(CN))
Potassium silver cyanide (Argentate(1-), bis(cyano-C)-, potassium)
Pronamide (Benzamide, 3,5-dichloro-N-(1,1-dimethyl-2-propynyl)-)
1,3-Propane sultone (1,2-Oxathiolane, 2,2-dioxide)
n-Propylamine (1-Propanamine)
Propargyl alcohol (2-Propyn-l-ol)
Propylene dichloride (Propane, 1,2-
dichloro-)
1,2-Propylenimine (Aziridine, 2-methyl-)
Propylthiouracil (4(1H)-Pyrimidinone, 2,3-dihydro-6-propyl-2-thioxo-)
Pyridine
Reserpinen (Yohimban-16-carboxylic acid,
11,17-dimethoxy-18-[(3,4,5-trimethoxybenzoyl)oxy]-smethyl ester, (3 beta ,16
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60 FR 2854, "2811
beta ,17 alpha ,18 beta ,20 alpha}-)
Resorcinol (1.3-Benzenediol)
Saccharin and salts (1,2-Benzisothiazol-3(2H)-one, 1,1-dioxide)
Safrole (1,3-Benzodioxole, 5-(2-propenyl)-)
Selenium and compounds, N.O.S.
Selenium dioxide (Selenious acid)
Selenium sulfide (SeS sub 2)
Selenourea
Silver and compounds, N.O.S.
Silver cyanide (Silver cyanide Ag(CN))
Silvex (Propanoic acid, 2 -(2,4,5-trichlorophen
oxy)-)
Sodium cyanide (Sodium cyanide Na(CN))
Streptozotocin (D-Glucose, 2-deoxy-2-[[methylnitrosoamino)carbonyl]amino]-)
Strychnine and salts (Strychnidin-10-one)
TCDD (Dibenzo[b,e][1,4]dioxin, 2,3,7,8-tetrachloro-)
1,2,4,5-Tetrachlorobenzene (Benzene, 1,2,4,5-tetrachloro-)
Tetrachlorodibenzo-p-dioxins
Tetrachlorodibenxofurans
Tetrachloroethane, N.O.S. (Ethane, tetrachloro-, N.O.S.)
1,1,1,2-Tetrachloroethane (Ethane, 1,1,1,2-tetrachloro-)
1,1,2,2-Tetrachloroethane (Ethane, 1,1,2,2-tetrachloro-)
Tetrachloroethylene (Ethene, tetrachloro-)
2,3,4,6-Tetrachlorophenol (Phenol, 2,3,4,6-tetrachloro-)
Tetraethyldithiopyrophosphate (Thiodiphosphoric acid, tetraethyl ester)
Tetraethyl lead (Plumbane, tetraethyl-)
Tetraethyl pyrophosphate (Diphosphoric acid, tetraethyl ester)
Tetranitromethane (Methane, tetranitro-)
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SO FR 2854, *2871
Thallium and compounds, N.O.S.
Thailie oxide (Thallium oxide Tl sub 20 sub 3)
Thallium (I) acetate (Acetic acid, thallium (1+) salt)
Thallium 'I) carbonate (Carbonic acid, dithallium (1 + ) salt)
Thallium (I) chloride (Thallium chloride T1C1)
Thallium (I) nitrate (Nitric acid, thallium (1+) salt)
Thallium selenite (Selenius acid, dithallium (1+) salt)
Thallium (I) sulfate (Sulfunc acid, thallium (1 + ) salt)
Thioacetamide (Ethanethioamide)
3,Thiofanox (2-Butanone, 3,3-dimethyl-l-(methylthio)-, 0-[(methylamino)carbonyl]
oxime)
Thiomethanol (Methanethiol)
Thiophenol (Benzenethiol)
Thiosemicarbazide (Hydrazinecarbothioatnide)
Thiourea
Thiram (Thioperoxydicarbonic diamide [(H sub 2N)C(S)]2S sub 2, tetramethyl-)
Toluene (Benzene, methyl-)
Toluenediamine (Benaenediamine, ar-methyl-)
Toluene-2,4-diamine (1,3-Benzenediamine, 4-methyl-)
Toluene-2,6-diamine (1,3-Benzenediamine, 2-methyl-)
Toluene-3,4-diamine (1,2-Benzenediamine, 4-methyl-)
Toluene diisocyanate (Benzene, 1, 3,-diisocyanatomethyl-)
o-Toluidine (Benzenamine, 2-methyl-)
o-Toluidine hydrochloride (Benzenamine, 2-methyl-, hydrochloride)
p-Toluidine (Benzenamine, 4-methyl-)
Toxaphene
1,2,4-Trichlorobenzene (Benzene, 1,2,4-trichloro-)
1,1,2-Trichloroethane (Ethane, 1,1,2-trichloro-)
U S Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th hoor
Chicago, IL 60604-3590
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60 FR 2854, *2871
Trichloroethylene (Ethene,trichloro-)
Trichloromethanethiol (Methanethiol, trichloro-)
Trichloromonofluoromethane (Methane, trichlorofluoro-)
2 , 4 , 5-Trichlorophenol .(Phenol, 2 , 4 , 5-trichloro-)
2,4,6-Trichlorophenol (Phenol, 2,4,6-trichloro-)
2,4,5-T (Acetic acid, 2,4,5- trichloro-
phenoxy-)
Trichloropropane, N.O.S.
1,2,3-Trichloropropane (Propane, 1,2,3-trichloro-)
0,0,0-Triethyl phosphorothioate (Phosphorothioic acid, 0,0,0-triethyl ester)
Trinitrobenzene (Benzene, 1,3,5-trinitro-)
Tris(l-aziridinyl)phosphine sulfide (Aziridine,
1,1',Vphosphinothioylidynetris-))
Tris(2,3-dibromopropyl) phosphate (1-Propanol, 2,3-dibromo-, phosphate (3:1))
Trypan blue (2,7-Naphthalendiaulfonic acid,
3,3'- [ (3,3'-dimethyl[1,1'-biphenyl]-4,4'-diyDbis(azo)]bis(5-amino-4-hydroxy-,
tetrasodium salt)
Uracil mustard (2,4-(1H,3H)-Pyrimidinedione, 5-[bis(2-chloroethyl)amino]-)
Vanadium pentoxide (Vanadium oxide V sub 20 sub 5)
Vinyl chloride (Ethene, chloro-)
Wayfarin (2H-l-Benzopyran-2-one, 4-hydroxy-3-(3-oxo-l-phenlybutyl)-)
Zinc cyanide (Zn(CN) sub 2)
Zinc phosphide (Zn sub 3P sub 2)
[FR Doc. 95-546 Filed 1-10-95; 8:45 am]
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