[Federal Register Volume 79, Number 85 (Friday, May 2, 2014)]
[Proposed Rules]
[Pages 25387-25412]
[FR Doc No: 2014-09728]

Vol. 79

Friday,

No. 85

May 2, 2014

Part III

Environmental Protection Agency

-----------------------------------------------------------------------

40 CFR Part 61

Revisions to National Emission Standards for Radon Emissions from
Operating Mill Tailings; Proposed Rule

Federal Register / Vol. 79, No. 85 / Friday, May 2, 2014 / Proposed
Rules

-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 61

[EPA-HQ-OAR-2008-0218; FRL-9816-2]
RIN 2060-AP26

Revisions to National Emission Standards for Radon Emissions From
Operating Mill Tailings

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

-----------------------------------------------------------------------

SUMMARY: The Environmental Protection Agency (EPA) is proposing to
revise certain portions of the National Emission Standards for
Hazardous Air Pollutants (NESHAP) for radon emissions from operating
uranium mill tailings. The proposed revisions are based on EPA's
determination as to what constitutes generally available control
technology or management practices (GACT) for this area source
category. We are also proposing to add new definitions to this rule,
revise existing definitions and clarify that the rule applies to
uranium recovery facilities that extract uranium through the in-situ
leach method and the heap leach method.

DATES: Comments must be received on or before July 31, 2014.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2008-0218, by one of the following methods:
     www.regulations.gov: Follow the on-line instructions for
submitting comments.
     Email<EMAIL_ADDRESS>     Fax:<PHONE_NUMBER>.
     Mail: Air and Radiation Docket, Environmental Protection
Agency, Mailcode: 2822T, 1200 Pennsylvania Ave. NW., Washington, DC
20460.
     Hand Delivery: EPA West Building, Room 3334, 1301
Constitution Ave. NW., Washington, DC 20004. Such deliveries are only
accepted during the Docket's normal hours of operation, and special
arrangements should be made for deliveries of boxed information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2008-0218. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
www.regulations.gov, including any personal information provided,
unless the comment includes information claimed to be Confidential
Business Information (CBI) or other information whose disclosure is
restricted by statute. Do not submit information that you consider to
be CBI or otherwise protected through www.regulations.gov or email. The
www.regulations.gov Web site is an ``anonymous access'' system, which
means EPA will not know your identity or contact information unless you
provide it in the body of your comment. If you send an email comment
directly to EPA without going through www.regulations.gov your email
address will be automatically captured and included as part of the
comment that is placed in the public docket and made available on the
Internet. If you submit an electronic comment, EPA recommends that you
include your name and other contact information in the body of your
comment and with any disk or CD-ROM you submit. If EPA cannot read your
comment due to technical difficulties and cannot contact you for
clarification, EPA may not be able to consider your comment. Electronic
files should avoid the use of special characters, any form of
encryption, and be free of any defects or viruses. For additional
information about EPA's public docket visit the EPA Docket Center
homepage at http://www.epa.gov/epahome/dockets.htm.
    Docket: All documents in the docket are listed in the
www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in www.regulations.gov or in hard copy at the Office of Air and
Radiation Docket, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave.
NW., Washington, DC. The Public Reading Room is open from 8:30 a.m. to
4:30 p.m., Monday through Friday, excluding legal holidays. The
telephone number for the Public Reading Room is<PHONE_NUMBER>, and the
telephone number for the Air and Radiation Docket is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: Reid J. Rosnick, Office of Radiation
and Indoor Air, Radiation Protection Division, Mailcode 6608J, U.S.
Environmental Protection Agency, 1200 Pennsylvania Ave. NW.,
Washington, DC 20460; telephone number:<PHONE_NUMBER>; fax number: 202-
343-2304; email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:
    Outline. The information in this preamble is organized as follows:

I. General Information
    A. Does this action apply to me?
    B. What should I consider as I prepare my comments to EPA?
    C. Acronyms and Abbreviations
    D. Where can I get a copy of this document?
    E. When would a public hearing occur?
II. Background Information for Proposed Area Source Standards
    A. What is the statutory authority for the proposed standards?
    B. What criteria did EPA use in developing the proposed GACT
standards for these area sources?
    C. What source category is affected by the proposed standards?
    D. What are the production operations, emission sources, and
available controls?
    E. What are the existing requirements under Subpart W?
    F. How did we gather information for this proposed rule?
    G. How does this action relate to other EPA standards?
    H. Why did we conduct an updated risk assessment?
III. Summary of the Proposed Requirements
    A. What are the affected sources?
    B. What are the proposed requirements?
    C. What are the monitoring requirements?
    D. What are the notification, recordkeeping and reporting
requirements?
    E. When must I comply with these proposed standards?
IV. Rationale for this Proposed Rule
    A. How did we determine GACT?
    B. Proposed GACT standards for operating mill tailings
V. Other Issues Generated by Our Review of Subpart W
    A. Clarification of the Term ``Standby''
    B. Amending the Definition of ``Operation'' for Conventional
Impoundments
    C. Weather Events
    D. Applicability of 40 CFR 192.32(a) to Subpart W
VI. Summary of Environmental, Cost and Economic Impacts
    A. What are the air impacts?
    B. What are the cost and economic impacts?
    C. What are the non-air environmental impacts?
VII. Statutory and Executive Order Review
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use
    I. National Technology Transfer Advancement Act
    J. Executive Order 12898: Federal Actions to Address
Environmental Justice in Minority Populations and Low-Income
Populations

I. General Information

A. Does this action apply to me?

    The regulated categories and entities potentially affected by the
proposed standards include:

------------------------------------------------------------------------
                                      NAICS
              Category                 code      Examples of regulated
                                       \1\             entities
------------------------------------------------------------------------
Industry:
    Uranium Ores Mining and/or        212291  Area source facilities
     Beneficiating.                            that extract or
                                               concentrate uranium from
                                               any ore processed
                                               primarily for its source
                                               material content.
    Leaching of Uranium, Radium or    212291  Area source facilities
     Vanadium Ores.                            that extract or
                                               concentrate uranium from
                                               any ore processed
                                               primarily for its source
                                               material content.
------------------------------------------------------------------------
\1\ North American Industry Classification System.

    This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be affected by this
proposed action. If you have any questions regarding the applicability
of this action to a particular entity, consult either the air permit
authority for the entity or your EPA regional representative as listed
in 40 CFR 61.04 of subpart A (General Provisions).

B. What should I consider as I prepare my comments for EPA?

    1. Submitting CBI. Do not submit this information to EPA through
www.regulations.gov or email. Clearly mark the part or all of the
information that you claim to be CBI. For CBI information in a disk or
CD ROM that you mail to EPA, mark the outside of the disk or CD ROM as
CBI and then identify electronically within the disk or CD ROM the
specific information that is claimed as CBI. In addition to one
complete version of the comment that includes information claimed as
CBI, a copy of the comment that does not contain the information
claimed as CBI must be submitted for inclusion in the public docket.
Information marked as CBI will not be disclosed except in accordance
with procedures set forth in 40 CFR part 2.
    2. Tips for Preparing Your Comments. When submitting comments,
remember to:
     Identify the rulemaking by docket number and other
identifying information (subject heading, Federal Register date and
page number).
     Follow directions--The agency may ask you to respond to
specific questions or organize comments by referencing a Code of
Federal Regulations (CFR) part or section number.
     Explain why you agree or disagree, suggest alternatives,
and substitute language for your requested changes.
     Describe any assumptions and provide any technical
information and/or data that you used.
     If you estimate potential costs or burdens, explain how
you arrived at your estimate in sufficient detail to allow for it to be
reproduced.
     Provide specific examples to illustrate your concerns, and
suggest alternatives.
     Explain your views as clearly as possible, avoiding the
use of profanity or personal threats.

Make sure to submit your comments by the comment period deadline
identified.

C. Acronyms and Abbreviations

    We use many acronyms and abbreviations in this document. These
include:

AEA--Atomic Energy Act
ALARA--As low as reasonably achievable
BID--Background information document
CAA--Clean Air Act
CAAA--Clean Air Act Amendments of 1990
CCAT--Colorado Citizens Against Toxic Waste
CFR--Code of Federal Regulations
Ci--Curie, a unit of radioactivity equal to the amount of a
radioactive isotope that decays at the rate of 3.7 x 10\10\
disintegrations per second.
DOE--U.S. Department of Energy
EIA--economic impact analysis
EO--Executive Order
EPA--U.S. Environmental Protection Agency
FR--Federal Register
GACT--Generally Available Control Technology
gpm--Gallons Per Minute
HAP--Hazardous Air Pollutant
ICRP--International Commission on Radiological Protection
ISL--In-situ leach uranium recovery, also known as in-situ recovery
(ISR)
LCF--Latent Cancer Fatality--Death resulting from cancer that became
active after a latent period following exposure to radiation
NAAQS--National Ambient Air Quality Standards
NCRP--National Council on Radiation Protection and Measurements
mrem--millirem, 1 x 10-\3\ rem
MACT--Maximum Achievable Control Technology
NESHAP--National Emission Standard for Hazardous Air Pollutants
NRC--U.S. Nuclear Regulatory Commission
OMB--Office of Management and Budget
pCi--picocurie, 1 x 10-\12\ curie
Ra-226--Radium-226
Rn-222--Radon-222
Radon flux--A term applied to the amount of radon crossing a unit
area per unit time, as in picocuries per square centimeter per
second (pCi/m\2\/sec).
RCRA--Resource Conservation and Recovery Act
Subpart W--National Emission Standards for Radon Emissions from
Operating Mill Tailings at 40 CFR 61.250-61.256
TEDE--Total Effective Dose Equivalent
UMTRCA--Uranium Mill Tailings Radiation Control Act of 1978
U.S.C.--United States Code

D. Where can I get a copy of this document?

    In addition to being available in the docket, an electronic copy of
this proposed action will also be available on the Worldwide Web (WWW)
through the Technology Transfer Network (TTN). Following signature, a
copy of this proposed action will be posted on the TTN's policy and
guidance page for newly proposed or promulgated rules at the following
address: http://www.epa.gov/ttn/oarpg/. The TTN provides information
and technology exchange in various areas of air pollution control.

E. When would a public hearing occur?

    If anyone contacts EPA requesting to speak at a public hearing
concerning this proposed rule by July 1, 2014, we will hold a public
hearing. If you are interested in attending the public hearing, contact
Mr. Anthony Nesky at<PHONE_NUMBER> to verify that a hearing will be
held and if you wish to speak. If a public hearing is held, we will
announce the date, time and venue on our Web site at http://www.epa.gov/radiation.

II. Background Information for Proposed Area Source Standards

A. What is the statutory authority for the proposed standards?

    Section 112(q)(1) of the Clean Air Act (CAA) requires that National
Emission Standards for Hazardous Air Pollutants (NESHAP) ``in effect
before the date of enactment of the Clean Air Act Amendments of 1990
[Nov. 15, 1990] . . . shall be reviewed and, if appropriate, revised,
to comply with the requirements of subsection (d) of . . . section
[112].'' EPA promulgated 40 CFR part 61, Subpart W, ``National Emission
Standards for Radon Emissions From Operating Mill Tailings,''
(``Subpart W'') on December 15, 1989.\1\ EPA is conducting this review
of Subpart W under CAA section 112(q)(1) to determine what revisions,
if any, are appropriate.
---------------------------------------------------------------------------

    \1\ On April 26, 2007, Colorado Citizens Against Toxic Waste and
Rocky Mountain Clean Air Action filed a lawsuit against EPA (EPA-HQ-
OAR-2008-0218-0013) for EPA's alleged failure to review and, if
appropriate, revise NESHAP Subpart W under CAA section 112(q)(1). A
settlement agreement was entered into between the parties in
November 2009(EPA-HQ-OAR-2008-0218-0019).
---------------------------------------------------------------------------

    Section 112(d) of the CAA requires EPA to establish emission
standards for major and area source categories that are listed for
regulation under CAA section 112(c). A major source is any stationary
source that emits or has the potential to emit 10 tons per year (tpy)
or more of any single hazardous air pollutant (HAP) or 25 tpy or more
of any combination of HAP. An area source is a stationary source of HAP
that is not a major source. For the purposes of Subpart W, the HAP at
issue is radon-222 (hereafter referred to as ``radon''). We presently
have no data or information that shows any other HAPs being emitted
from these impoundments. Calculations of radon emissions from operating
uranium recovery facilities have shown that facilities regulated under
Subpart W are area sources (EPA-HQ-OAR-2008-0218-0001, 0002).
    Section 112(q)(1) does not dictate how EPA must conduct its review
of those NESHAPs issued prior to 1990. Rather, it provides that the
Agency must review, and if appropriate, revise the standards to comply
with the requirements of section 112(d). Determining what revisions, if
any, are appropriate for these NESHAPs is best assessed through a case-
by-case consideration of each NESHAP. As explained below, in this case,
we have reviewed Subpart W and are revising the standards consistent
with section 112(d)(5), which provides EPA authority to issue standards
for area sources.
    Under CAA section 112(d)(5), the Administrator may elect to
promulgate standards or requirements for area sources ``which provide
for the use of generally available control technologies or management
practices by such sources to reduce emissions of hazardous air
pollutants.'' Under section 112(d)(5), the Administrator has the
discretion to use generally available control technology or management
practices (GACT) in lieu of maximum achievable control technology
(MACT) under section 112(d)(2) and (d)(3), which is required for major
sources. Pursuant to section 112(d)(5), we are proposing revisions to
Subpart W to reflect GACT.

B. What criteria did EPA use in developing the proposed GACT standards
for these area sources?

    Additional information on generally available control technologies
or management practices (GACT) is found in the Senate report on the
legislation (Senate Report Number 101-228, December 20, 1989), which
describes GACT as:

* * * methods, practices and techniques which are commercially
available and appropriate for application by the sources in the
category considering economic impacts and the technical capabilities
of the firms to operate and maintain the emissions control systems.

Consistent with the legislative history, we can consider costs and
economic impacts in determining GACT, which is particularly important
when developing regulations for source categories, like this one, that
may include small businesses.
    Determining what constitutes GACT involves considering the control
technologies and management practices that are generally available to
the area sources in the source category. We also consider the standards
applicable to major sources \2\ in the same industrial sector to
determine if the control technologies and management practices are
transferable and generally available to area sources. In appropriate
circumstances, we may also consider technologies and practices at area
and major sources in similar categories to determine whether such
technologies and practices could be considered generally available for
the area source category at issue. Finally, as noted above, in
determining GACT for a particular area source category, we consider the
costs and economic impacts of available control technologies and
management practices on that category.
---------------------------------------------------------------------------

    \2\ None of the sources in this source category are major
sources.
---------------------------------------------------------------------------

C. What source category is affected by the proposed standards?

    As defined by EPA pursuant to the CAA, the source category for
Subpart W is ``facilities licensed [by the U.S. Nuclear Regulatory
Commission (NRC)] to manage uranium byproduct material during and
following the processing of uranium ores, commonly referred to as
uranium mills and their associated tailings.'' 40 CFR 61.250. Subpart W
defines ``uranium byproduct material or tailings'' as ``the waste
produced by the extraction or concentration of uranium from any ore
processed primarily for its source material content.'' \3\ 40 CFR
61.251(g). For clarity, in this proposed rule we refer to this source
category by the term ``uranium recovery facilities'' and we are
proposing to add this phrase to the definitions section of the rule.
Use of this term encompasses the existing universe of facilities whose
HAP emissions are currently regulated under Subpart W. Uranium recovery
facilities process uranium ore to extract uranium. The HAP emissions
from any type of uranium recovery facility that manages uranium
byproduct material or tailings is subject to regulation under Subpart
W. This currently includes three types of uranium recovery facilities:
(1) Conventional uranium mills; (2) in-situ leach recovery facilities;
and (3) heap leach facilities. Subpart W requirements specifically
apply to the affected sources at the uranium recovery facilities that
are used to manage or contain the uranium byproduct material or
tailings. Common names for these structures may include, but are not
limited to, impoundments, tailings impoundments, evaporation or holding
ponds, and heap leach piles. However, the name itself is not important
for determining whether Subpart W requirements apply to that structure;
rather, applicability is based

on the use of these structures to manage or contain uranium byproduct
material.
---------------------------------------------------------------------------

    \3\ Pursuant to the Atomic Energy Act of 1954, as amended, the
Nuclear Regulatory Commission defines ``source material'' as ``(1)
Uranium or thorium or any combination of uranium or thorium in any
chemical or physical form; or (2) Ores that contain, by weight, one-
twentieth of one percent (0.05 percent), or more, of uranium or
thorium, or any combination of uranium or thorium.'' (10 CFR
20.1003) For a uranium recovery facility licensed by the Nuclear
Regulatory Commission under 10 CFR Part 40, ``byproduct material''
means the ``tailings or wastes produced by the extraction or
concentration of uranium or thorium from ore processed primarily for
its source material content, including discrete surface wastes
resulting from uranium solution extraction processes.'' (10 CFR
20.1003 and 40.4)
---------------------------------------------------------------------------

D. What are the production operations, emission sources, and available
controls?

    As noted above, uranium recovery and processing currently occurs by
one of three methods: (1) Conventional milling; (2) in-situ leach
(ISL); and (3) heap leach. Below we present a brief explanation of the
various uranium recovery methods and the usual structures that contain
uranium byproduct materials.
(1) Conventional Mills
    Conventional milling is one of the two primary recovery methods
that are currently used to extract uranium from uranium-bearing ore.
Conventional mills are typically located in areas of low population
density. Only one conventional mill in the United States is currently
operating; all others are in standby, in decommissioning (closure) or
have been decommissioned.
    A conventional uranium mill is a chemical plant that extracts
uranium using the following process:
    (A) Trucks deliver uranium ore to the mill, where it is crushed
before the uranium is extracted through a leaching process. In most
cases, sulfuric acid is the leaching agent, but alkaline solutions can
also be used to leach the uranium from the ore. The process generally
extracts 90 to 95 percent of the uranium from the ore.
    (B) The mill then concentrates the extracted uranium to produce a
uranium oxide material which is called ``yellowcake'' because of its
yellowish color.\4\
---------------------------------------------------------------------------

    \4\ The term ``yellowcake'' is still commonly used to refer to
this material, although in addition to yellow the uranium oxide
material can also be black or grey in color.
---------------------------------------------------------------------------

    (C) Finally, the yellowcake is transported to a uranium conversion
facility where it is processed through the stages of the nuclear fuel
cycle to produce fuel for use in nuclear power reactors.
    (D) The extraction process in (A) and (B) above produces both solid
and liquid wastes (i.e., uranium byproduct material, or ``tailings'')
which are transported from the extraction location to an on-site
tailings impoundment or a pond for temporary storage.
    Uranium byproduct material/tailings are typically created in slurry
form during the crushing, leaching and concentration processes and are
then deposited in an impoundment or ``mill tailings pile'' which must
be carefully monitored and controlled. This is because the mill
tailings contain heavy metal ore constituents, including radium. The
radium decays to produce radon, which may then be released to the
environment. Because radon is a radioactive gas which may be inhaled
into the respiratory tract, EPA has determined that exposure to radon
and its daughter products contributes to an increased risk of lung
cancer.\5\
---------------------------------------------------------------------------

    \5\ http://www.epa.gov/radon/risk_assessment.html.
---------------------------------------------------------------------------

    The holding or evaporation ponds at this type of facility hold
liquids containing byproduct material from which HAP emissions are also
regulated under Subpart W. These ponds are discussed in more detail in
the next section.
(2) In-Situ Leach/Recovery
    In-situ leach or recovery sites (ISL/ISR, in this document we will
use ISL) represent the majority of the uranium recovery operations that
currently exist. The research and development projects and associated
pilot projects of the 1980s demonstrated ISL as a viable uranium
recovery technique where site conditions (e.g., geology) are amenable
to its use. Economically, this technology produces a better return on
the investment dollar (EPA-HQ-OAR-2008-0218-0087); therefore, the cost
to produce uranium is more favorable to investors. Due to this, the
trend in uranium production has been toward the ISL process.
    In-situ leaching is defined as the underground leaching or recovery
of uranium from the host rock (typically sandstone) by chemicals,
followed by recovery of uranium at the surface. Leaching, or more
correctly the re-mobilization of uranium into solution, is accomplished
through the underground injection of a lixiviant (described below) into
the host rock (i.e., ore body) through wells that are connected to the
ore formation. A lixiviant is a chemical solution used to extract (or
leach) uranium from underground ore bodies.
    The injection of a lixiviant essentially reverses the geochemical
reactions that resulted in the formation of the uranium deposit. The
lixiviant assures that the dissolved uranium, as well as other metals,
remains in the solution while it is collected from the ore zone by
recovery wells, which pump the solution to the surface. At the surface,
the uranium is recovered in an ion-exchange column and further
processed into yellowcake. The yellowcake is packaged and transported
to a uranium conversion facility where it is processed through the
stages of the nuclear fuel cycle to produce fuel for use in nuclear
power reactors.
    Two types of lixiviant solutions can be used, loosely defined as
``acid'' or ``alkaline'' systems. In the U.S., the geology and
geochemistry of the majority of the uranium ore bodies favors the use
of alkaline lixiviants such as bicarbonate-carbonate lixiviant and
oxygen. Other factors in the choice of the lixiviant are the uranium
recovery efficiencies, operating costs, and the ability to achieve
satisfactory ground-water restoration.
    After processing, lixiviant is recharged (more carbonate/
bicarbonate or dissolved carbon dioxide is added to the solution) and
pumped back down into the formation for reuse in extracting more
uranium. However, a small amount of this liquid is held back from
reinjection to maintain a proper hydraulic gradient \6\ within the
wellfield. The amount of liquid held back is a function of the
characteristics of the formation properties (e.g., permeability,
hydraulic conductivity, transmissivity). This excess liquid is sent to
an impoundment (often called an evaporation pond or holding pond) on
site or injected into a deep well for disposal. These impoundments,
since they contain uranium byproduct material, are subject to the
requirements of Subpart W.\7\ With respect to the lixiviant reinjected
into the wellfield, there is a possibility of the lixiviant spreading
beyond the zone of the uranium deposit (excursion), and this produces a
threat of ground-water contamination. The operator of the ISL facility
remediates any excursion by pumping large amounts of water in or out of
the formation (at various wells) to contain the excursion, and this
water (often containing byproduct material either before or after
injection into or withdrawal from the formation) is often stored in the
evaporation or holding ponds.\8\ Although the excursion control
operation itself is not regulated under Subpart W, the ponds that
contain byproduct material are regulated under that subpart, since they
are a potential source of radon emissions. After the ore body has been
depleted, restoration of the formation (attempting to return the
formation back to its original geochemical and geophysical

properties) is accomplished by flushing the host rock with water and
sometimes additional chemicals. Since small amounts of uranium are
still contained in the returning water, the restoration fluids are also
considered byproduct material, and are usually sent to evaporation
ponds for disposition.
---------------------------------------------------------------------------

    \6\ The hydraulic gradient determines which direction water in
the formation will flow, which in this case limits the amount of
water that migrates away from the ore zone.
    \7\ As described later in this preamble, the design requirements
for these impoundments are derived from the RCRA requirements for
impoundments.
    \8\ By controlling the hydraulic gradient of the formation the
operator controls the direction of flow of water, containing the
water within specified limits of the formation.
---------------------------------------------------------------------------

(3) Heap Leaching
    In addition to conventional uranium milling and ISL, some
facilities may use an extraction method known as heap leaching. In some
instances uranium ore is of such low grade, or the geology of the ore
body is such that it is not cost-effective to remove the uranium via
conventional milling or through ISL.\9\ In this case a heap leaching
method may be utilized.
---------------------------------------------------------------------------

    \9\ The ore grade is so low that it is not practical to invest
large sums of capital to extract the uranium. Heap leach is a much
more passive and relatively inexpensive system.
---------------------------------------------------------------------------

    No such facilities currently operate to recover uranium in the U.S.
However, there are plans for at least one facility to open in the U.S.
within the next few years.
    Heap leach operations involve the following process:

    A. Small pieces of ore are placed in a large pile, or ``heap,''
on an impervious geosynthetic liner with perforated pipes under the
heap. For the purposes of Subpart W the impervious pad will meet the
requirements for design and construction of impoundments found at 40
CFR 192.32(a).
    B. An acidic solution is then sprayed \10\ over the ore to
dissolve the uranium it contains.
---------------------------------------------------------------------------

    \10\ Other technology includes drip systems, sometimes used at
gold extraction heaps, and flooding of the heap leach pile.
---------------------------------------------------------------------------

    C. The uranium-rich solution drains into the perforated pipes,
where it is collected and transferred to an ion-exchange system.
    D. The heap is ``rested,'' meaning that there is a temporary
cessation of application of acidic solution to allow for oxidation
of the ore before leaching begins again.
    E. The ion-exchange system extracts the uranium from solution
where it is later processed into a yellowcake.\11\
---------------------------------------------------------------------------

    \11\ It is our understanding that either ion-exchange or solvent
extraction techniques can be used to recover uranium at heap leach
facilities. The decision to use one type or the other depends
largely on the quality of the ore at a particular site.
---------------------------------------------------------------------------

    F. Once the uranium has been extracted, the remaining solution
still contains small amounts of uranium byproduct material (the
extraction process is not 100% effective), and this solution is
either piped to the heap leach pile to be reused or piped to an
evaporation or holding pond. In the evaporation pond it is subject
to the Subpart W requirements.
    G. The yellowcake is transported to a uranium conversion
facility where it is processed through the stages of the nuclear
fuel cycle to produce fuel for use in nuclear power reactors.
    H. Finally, there is a final drain down of the heap solutions,
as well as a possible rinsing of the heap. These solutions will
contain byproduct material and will be piped to evaporation or
holding ponds, where they become subject to the Subpart W
requirements. The heap leach pile will be closed in place according
to the requirements of 40 CFR 192.32.

    Today we are proposing to regulate the HAP emissions from heap
leach uranium extraction under Subpart W, in addition to conventional
impoundments and evaporation ponds, which are already regulated under
this Subpart. Our rationale (explained in greater detail in Section
IV.D.4.) is that from the moment uranium extraction takes place in the
heap, uranium byproduct material is left behind. Therefore the
byproduct material must be managed with the same design as a
conventional impoundment, with a liner and leak detection system
prescribed at 40 CFR 192.32(a), and an effective method of limiting
radon emissions while the heap leach pile is being used to extract
uranium.
    As described above, there may also be holding or evaporation ponds
at this type of facility. In many cases these ponds hold liquids
containing byproduct material. The byproduct material is contained in
the liquids used to leach uranium from the ore in the heap leach pile
as well as draining the heap leach pile in preparation for closure. The
HAP emissions from these fluids are currently regulated under Subpart
W.

E. What are the existing requirements under Subpart W?

    Subpart W was promulgated on December 15, 1989 (54 FR 51654). At
the time of promulgation the predominant form of uranium recovery was
through the use of conventional mills. There are two separate standards
required in Subpart W. The first standard is for ``existing''
impoundments, e.g., those in existence and licensed by the NRC (or it's
Agreement States) on or prior to December 15, 1989. Owners or operators
of existing tailings impoundments must ensure that emissions from those
impoundments do not exceed a radon (Rn-222) flux standard of 20
picocuries per meter squared per second (pCi/m\2\/sec). As stated at
the time of promulgation: ``This rule will have the practical effect of
requiring the mill owners to keep their piles wet or covered.''\12\
Keeping the piles (impoundments) wet or covered with soil would reduce
radon emissions to a level that would meet the standard. This is still
considered an effective method to reduce radon emissions at all uranium
tailings impoundments.
---------------------------------------------------------------------------

    \12\ See 54 FR 51689.
---------------------------------------------------------------------------

    The method for monitoring for compliance with the radon flux
standard was prescribed as Method 115, found at 40 CFR part 61,
Appendix B. The owners or operators of existing impoundments must
report to EPA the results of the compliance testing for any calendar
year by no later than March 31 of the following year.
    There is currently one existing operating mill with impoundments
that pre-date December 15, 1989, and two mills that are currently in
standby mode.
    The second standard applies to ``new'' impoundments designed and/or
constructed after December 15, 1989. The requirements applicable to new
impoundments are work practice standards that regulate either the size
and number of impoundments, or the amount of tailings that may remain
uncovered at any time. 40 CFR 61.252(b) states that no new tailings
impoundment can be built after December 15, 1989, unless it is
designed, constructed and operated to meet one of the following two
work practices:

    1. Phased disposal in lined impoundments that are no more than
40 acres in area, and meet the requirements of 40 CFR 192.32(a) as
determined by the NRC. The owner or operator shall have no more than
two impoundments, including existing impoundments, in operation at
any one time.
    2. Continuous disposal of tailings that are dewatered and
immediately disposed with no more than 10 acres uncovered at any
time, and operated in accordance with 40 CFR 192.32(a) as determined
by the NRC.

    The basis of the work practice standards is to (1) limit the size
of the impoundment, which limits the radon source; or (2) utilize the
continuous disposal system, which prohibits large accumulations of
uncovered tailings, limiting the amount of radon released.
    The work practice standards described above were promulgated after
EPA considered a number of factors that influence the emissions of Rn-
222 from tailings impoundments, including the climate and the size of
the impoundment. For example, for a given concentration of Ra-226 in
the tailings, and a given grain size of the tailings, the moisture
content of the tailings will control the radon emission rate; the
higher the moisture content the lower the emission rate. In the arid
and semi-arid areas of the country where most impoundments are located
or proposed, the annual evaporation rate is quite high. As a result,
the exposed tailings

(absent controls like sprinkling) dry rapidly. In previous assessments,
we explicitly took the fact of rapid drying into account by using a Rn-
222 flux rate of 1 pCi/m\2\/s per pCi/g Ra-226 to estimate the Rn-222
source term from the dry areas of the impoundments. (Note: The
estimated source terms from the ponded (areas completely covered by
liquid) and saturated areas of the impoundments are considered to be
zero, reflecting the complete attenuation of the Rn-222).
    Another factor we considered was the area of the impoundment, which
has a direct linear relationship with the Rn-222 source term, more so
than the depth or volume of the impoundment. Again, assuming the same
Ra-226 concentration and grain sizes in the tailings, a 100-acre dry
impoundment will emit 10 times the radon of a 10-acre dry impoundment.
This linear relationship between size and Rn-222 source term is one of
the main reasons that Subpart W imposed size restrictions on all future
impoundments (40 acres per impoundment if phased disposal is chosen and
10 acres total uncovered if continuous disposal is chosen).
    Subpart W also mandates that all tailings impoundments at uranium
recovery facilities comply with the requirements at 40 CFR 192.32(a).
EPA explained the reason for adding this requirement in the preamble as
follows:

    ``EPA recognizes that in the case of a tailings pile which is
not synthetically or clay lined (the clay lining can be the result
of natural conditions at the site) water placed on the tailings in
an amount necessary to reduce radon levels, can result in ground
water contamination. In addition, in certain situations the water
can run off and contaminate surface water. EPA cannot allow a
situation where the reduction of radon emissions comes at the
expense of increased pollution of the ground or surface water.
Therefore, all piles will be required to meet the requirements of 40
CFR 192.32(a) which protects water supplies from contamination.
Under the current rules, existing piles are exempt from these
provisions, this rule will end that exemption.''

54 FR 51654, 51680 (December 15, 1989). Therefore, all impoundments are
required to meet the requirements at 40 CFR 192.32(a).
    Section 192.32(a) includes a cross-reference to the surface
impoundment design and construction requirements of hazardous waste
surface impoundments regulated under the Resource Conservation and
Recovery Act (RCRA), found at 40 CFR 264.221. Those requirements state
that the impoundment shall be designed, constructed and installed to
prevent any migration of wastes out of the impoundment to the adjacent
subsurface soil or ground water or surface water at any time during the
active life of the impoundment. Briefly, 40 CFR 264.221(c) requires
that the liner system must include:

    1. A top liner designed and constructed of materials (e.g., a
geomembrane) to prevent the migration of hazardous constituents into
the liner during the active life of the unit.
    2. A composite bottom liner consisting of at least two
components. The upper component must be designed and constructed of
materials (e.g., a geomembrane) to prevent the migration of
hazardous constituents into this component during the active life of
the unit. The lower component must be designed and constructed of
materials to minimize the migration of hazardous constituents if a
breach in the upper component were to occur. The lower component
must be constructed of at least three feet of compacted soil
material with a hydraulic conductivity of no more than 1 x 10\-7\
cm/sec.
    3. A leachate collection and removal system between the liners,
which acts as a leak detection system. This system must be capable
of detecting, collecting and removing hazardous constituents at the
earliest practicable time through all areas of the top liner likely
to be exposed to the waste or liquids in the impoundment.

There are other requirements for the design and operation of the
impoundment, and these include construction specifications, slope
requirements, sump and liquid removal requirements.\13\
---------------------------------------------------------------------------

    \13\ For detailed information on the design and operating
requirements, refer to 40 CFR Part 264 Subpart K--Surface
Impoundments.
---------------------------------------------------------------------------

F. How did we gather information for this proposed rule?

    This section describes the information we used as the basis for
making the determination to revise Subpart W. We collected this
information using various methods. We performed literature searches,
where appropriate, of the engineering methods used by existing uranium
recovery facilities in the United States as well as the rest of the
world. We used this information to determine whether the technology
used to contain uranium byproduct material had advanced since the time
of the original promulgation of Subpart W. We reviewed and compiled a
list of existing and proposed uranium recovery facilities and the
containment technologies being used, as well as those proposed to be
used. We compared and contrasted those technologies with the
engineering requirements of hazardous waste surface impoundments
regulated under Subtitle C of the Resource Conservation and Recovery
Act (RCRA), which are used as the design basis for existing uranium
byproduct material impoundments.
    We collected information on existing uranium mills and in-situ
leach facilities by issuing information collection requests authorized
under section 114(a) of the CAA to seven uranium recovery facilities.
At the time, this represented 100% of existing facilities. Since then,
Cotter Corp. has closed its Canon City facility. These requests
required uranium recovery companies to provide detailed information
about the uranium mill and/or in-situ leaching facility, as well as the
number, sizes and types of affected sources (tailings impoundments,
evaporation ponds and collection ponds) that now or in the past held
uranium byproduct material. We requested information on the history of
operation since 1975, ownership changes, whether the operation was in
standby mode and whether plans existed for new facilities or
reactivated operations were expected.\14\ We also reviewed the
regulatory history of Subpart W and the radon measurement methods used
to determine compliance with the existing standards. Below is a
synopsis of the information we collected and our analyses.
---------------------------------------------------------------------------

    \14\ Section 114(a) letters and responses can be found at http://www.epa.gov/radiation/neshaps/subpartw/rulemaking-activity.html.
---------------------------------------------------------------------------

1. Pre-1989 Conventional Mill Impoundments
    We have been able to identify three facilities, either operating or
on standby,\15\ that have been in operation since before the
promulgation of Subpart W in 1989. These existing facilities must
ensure that emissions from their operational, pre-1989 impoundments\16\
not exceed a radon (Rn-222) flux standard of 20 pCi/m\2\/sec. The
method for monitoring for compliance with the radon flux standard was
prescribed as Method 115, found at 40 CFR part 61, Appendix B. These
facilities must also meet the requirements in 40 CFR 61.252(c), which
cross-references the requirements of 40 CFR 192.32(a)
---------------------------------------------------------------------------

    \15\ ``Standby'' is when a facility impoundment is licensed for
the continued placement of tailings/byproduct material but is
currently not receiving tailings/byproduct material. See Section
V.A. for a discussion of this definition that we are proposing to
add to Subpart W.
    \16\ In this preamble when we use the generic term
``impoundment,'' we are using the term as described by industry.
---------------------------------------------------------------------------

    The White Mesa Conventional Mill in Blanding, Utah, has one pre-
1989 impoundment (known by the company as Cell 3) that is currently in
operation and near capacity but is still authorized and continues to
receive tailings. The

company is now pumping any residual free solution out of the cell and
contouring the sands. It will then be determined whether any more
solids need to be added to the cell to fill it to the specified final
elevation. It is expected to close in the near future (EPA-HQ-OAR-2008-
0218-0069). The mill also uses an impoundment constructed before 1989
as an evaporation pond (known as Cell 1). To the extent this
evaporation pond contains byproduct material, its HAP emissions are
also regulated by Subpart W.
    The Sweetwater conventional mill is located 42 miles northwest of
Rawlins, Wyoming. The mill operated for a short time in the 1980s and
is currently in standby status. Annual radon values collected by the
facility indicate that there is little measurable radon flux from the
mill tailings that are currently in the lined impoundment. This
monitoring program remains active at the facility. According to company
records, of the 37 acres of tailings, approximately 28.3 acres of
tailings are covered with soil; the remainder of the tailings are
continuously covered with water. The dry tailings have an earthen cover
that is maintained as needed. During each monitoring event one hundred
radon flux measurements are taken on the tailings continuously covered
by soil, as required by Method 115 for compliance with Subpart W. The
mean radon flux for the exposed tailings over the past 21 years was 3.5
pCi/m \2\/sec. The radon flux for the entire tailings impoundment was
calculated to be 6.01 pCi/m \2\/sec. The calculated radon flux from the
entire tailings impoundment surface is thus approximately 30% of the
20.0 pCi/m \2\/sec standard (EPA-HQ-OAR-2008-0218-0087).
    The Shootaring Canyon project is a conventional mill located about
3 miles north of Ticaboo, Utah, in Garfield County. The approximately
1,900-acre site includes an ore pad, a small milling building, and a
tailings impoundment system that is partially constructed. The mill
operated for a very short period of time. Shootaring Canyon did pre-
date the standard, but the mill was shut down prior to the promulgation
of the standard. The impoundment is in a standby status and has an
active license administered by the Utah Department of Environmental
Quality, Division of Radiation Control. The future plans for this
uranium recovery operation are unknown. Current activities at this
remote site consist of intermittent environmental monitoring by
consultants to the parent company (EPA-HQ-OAR-2008-0218-0087).
    The Shootaring Canyon mill operated for approximately 30 days.
Tailings were deposited in a portion of the upper impoundment. A lower
impoundment was conceptually designed but has not been built. Milling
operations in 1982 produced 25,000 cubic yards of tailings, deposited
in a 2,508 m \2\ (0.62 acres) area. The tailings are dry except for
moisture associated with occasional precipitation events; consequently,
there are no beaches.\17\ The tailings have a soil cover that is
maintained by the operating company. Radon sampling for the 2010 year
took place in April. Again, one hundred radon flux measurements were
collected. The average radon flux from this sampling event was 11.9
pCi/m \2\-sec.
---------------------------------------------------------------------------

    \17\ The term ``beaches'' refers to portions of the tailings
impoundment where the tailings are wet but not saturated or covered
with liquids.
---------------------------------------------------------------------------

    A fourth mill is Cotter Corporation in Canon City, Colorado. The
mill no longer exists, and the pre-1989 impoundments are in closure.
2. 1989-Present Conventional Mill Impoundments
    There currently is only one operating conventional mill with an
impoundment that was constructed after December 15, 1989. The White
Mesa conventional mill in Utah has two impoundments (Cell 4A and Cell
4B: Cell 4A is currently operating as a conventional impoundment and
Cell 4B is being used as an evaporation pond) designed and constructed
after 1989. The facility uses the phased disposal work practice.
    There are several conventional mills in the planning and/or
permitting stage and conventional impoundments at these mills will be
required to utilize one of the current work practice standards.
3. In-Situ Leach Facilities
    After 1989 the price of uranium began to fall, and the uranium
mining and milling industry essentially collapsed, with very few
operations remaining in business. However, several years ago the price
of uranium began to rise so that it became profitable once more for
companies to consider uranium recovery. ISL has become the preferred
choice for uranium extraction where suitable geologic conditions exist.
    Currently there are five ISL facilities in operation: (1) The Alta
Mesa project in Brooks County, Texas; (2) the Crow Butte Operation in
Dawes County, Nebraska; (3) the Hobson/La Palangana Operation in South
Texas; (4) the Willow Creek (formerly Christensen Ranch/Irigaray Ranch)
Operation in Wyoming; and (5) the Smith Ranch-Highland Operation in
Converse County, Wyoming.\18\ These facilities use or have used
evaporation ponds to hold back liquids containing uranium byproduct
material from reinjection to maintain a proper hydraulic gradient
within the wellfield.\19\ These ponds are subject to the Subpart W
requirements and range in size from less than an acre to up to 40
acres. Based on the information provided to us the ponds meet the
requirements of 40 CFR 61.252(c).
---------------------------------------------------------------------------

    \18\ Source: U.S. Energy Information Administration, http://www.eia.gov/uranium/production/quarterly/html/qupd_tbl4.html.
    \19\ The Alta Mesa operation uses deep well injection rather
than evaporation ponds.
---------------------------------------------------------------------------

    There are approximately 11 additional ISL facilities in various
stages of licensing or on standby. It is anticipated that there could
be approximately another 20-30 license applications over the next 5-10
years.\20\
---------------------------------------------------------------------------

    \20\ Source: http://www.nrc.gov/materials/uranium-recovery/license-apps/ur-projects-list-public.pdf.
---------------------------------------------------------------------------

4. Heap Leach Facilities
    As stated earlier, there are currently no operating heap leach
facilities in the United States. We are aware of two or three potential
future operations. The project most advanced in the application process
is the Sheep Mountain facility in Wyoming. Energy Fuels has announced
its intent to submit a license application to the NRC in March 2014.
One or two other as yet to be determined operations may be located in
Lander County, Nevada and/or a site in New Mexico.\21\
---------------------------------------------------------------------------

    \21\ http://www.nrc.gov/materials/uranium-recovery/license-apps/ur-projects-list-public.pdf.
---------------------------------------------------------------------------

5. Flux Requirement Versus Management Practices for Conventional
Impoundments in Operation Before December 15, 1989
    In performing our analysis we considered the information we
received from all the existing conventional impoundments. We also
looked at the compliance history of the existing conventional
impoundments. After this review we considered two specific questions:
(1) Are any of the conventional impoundments using any novel methods to
reduce radon emissions? (2) Is there now any reason to believe that any
of the existing conventional impoundments could not comply with the
management practices for new conventional impoundments, in which case
would we need to continue to make the distinction between conventional
impoundments constructed before or after December 15, 1989? We arrived
at the following

conclusions: First, we are not aware of any conventional impoundment
that uses any new or different technologies to reduce radon emissions.
Conventional impoundment operators continue to use the standard method
of reducing radon emissions by limiting the size of the impoundment and
covering tailings with soil or keeping tailings wet. These are very
effective methods for limiting the amount of radon released to the
environment.
    Second, we believe that only one existing operating conventional
impoundment designed and in operation before December 15, 1989, could
not meet the work practice standards. This impoundment is Cell 3 at the
White Mesa mill, which is expected to close in 2014 (Personal
communication between EPA staff and Utah Department of Environmental
Quality staff, May 16, 2013, EPA-HQ-2008-0218-0081). We were very clear
in our 1989 rulemaking that all conventional mill impoundments must
meet the requirements of 40 CFR 192.32(a), which, in addition to
requiring ground-water monitoring, also required the use of liner
systems to ensure there would be no leakage from the impoundment into
the ground water. We did this by removing the exemption for existing
piles from the 40 CFR 192.32(a) requirements (54 FR 51680). However, we
did not require those existing impoundments to meet either the phased
disposal or continuous disposal work practice standards, which limit
the exposed area and/or number of conventional impoundments, thereby
limiting the potential for radon emissions. This is because at the time
of promulgation of the rule, conventional impoundments existed that
were larger in area than the maximum work practice standard of 40 acres
used for the phased disposal work practice, or 10 acres for the
continuous disposal requirement. This area limitation was important in
reducing the amount of exposed tailings that were available to emit
radon. However, we recognized that by instituting a radon flux standard
we would require owners and operators to limit radon emissions from
these preexisting impoundments (usually by placing water or soil on
exposed portions of the impoundments). The presumption was that
conventional impoundments constructed before this date could otherwise
be left in a dry and uncovered state, which would allow for unfettered
release of radon. The flux standard was promulgated to have the
practical effect of requiring owners and operators of these old
impoundments to keep their tailings either wet or covered with soil,
thereby reducing the amount of radon that could be emitted (54 FR
51680).
    We believe that the existing conventional impoundments at both the
Shootaring Canyon and Sweetwater facilities can meet the work practice
standards in the current Subpart W regulation. The conventional
impoundments at both these facilities are less than 40 acres in area
and are synthetically lined as per the requirements in 40 CFR
192.32(a). We also have information that the new conventional
impoundments operating at the White Mesa mill will utilize the phased
work practice standard of limiting conventional impoundments to no more
than two, each 40 acres or less in area. We also have information that
Cell 3 at the White Mesa facility will be closed in 2014, and the
phased disposal work method will be used for the remaining cells.
(Personal communication between EPA staff and staff of Utah Department
of Environmental Quality, May 16, 2013 (EPA-HQ-2008-0218-0081). As a
result, we find there would be no conventional impoundment designed or
constructed before December 15, 1989 that could not meet a work
practice standard. Since the conventional impoundments in existence
prior to December 15, 1989 appear to meet the work practice standards,
we are proposing to eliminate the distinction of whether the
conventional impoundment was constructed before or after December 15,
1989. We are also proposing that all conventional impoundments
(including those in existence prior to December 15, 1989) must meet the
requirements of one of the two work practice standards, and that the
flux standard of 20 pCi/m\2\/sec will no longer be required for the
impoundments in existence prior to December 15, 1989.

G. How does this action relate to other EPA standards?

    Under the CAA, EPA promulgated Subpart W, which includes standards
and other requirements for controlling radon emissions from operating
mill tailings at uranium recovery facilities. Under our authority in
the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA), we
have also issued standards that are more broadly applicable to uranium
and thorium byproduct materials at active and inactive uranium recovery
facilities. NRC (or Agreement States \22\) and DOE implement and
enforce these standards at these uranium recovery facilities as
directed by UMTRCA. These standards, located in 40 CFR part 192,
address the radiological and non-radiological hazards of uranium and
thorium byproduct materials in ground water and soil, in addition to
air. For the non-radiological hazards, UMTRCA directed us to promulgate
standards consistent with those used by EPA to regulate non-
radiological hazardous materials under RCRA. Therefore, our part 192
standards incorporate the ground-water protection requirements applied
to hazardous waste management units under RCRA and specify the
placement of uranium or thorium byproduct materials in impoundments
constructed in accordance with RCRA requirements. Radon emissions from
non-operational impoundments (i.e., those with final covers) are
limited in 40 CFR part 192 to the emissions levels of 20 pCi/m\2\/sec.
We are currently preparing a regulatory proposal to update provisions
of 40 CFR part 192, with emphasis on ground-water protection for ISL
facilities. As explained in previous sections, Subpart W currently
contains reference to some of the part 192 standards.
---------------------------------------------------------------------------

    \22\ An Agreement State is a State that has entered into an
agreement with the Nuclear Regulatory Commission under section 274
of the Atomic Energy Act of 1954 (42 U.S.C. 2021)and has authority
to regulate byproduct materials (as defined in section 11e.(2)of the
Atomic Energy Act)and the disposal of low-level radioactive waste
under such agreement.
---------------------------------------------------------------------------

H. Why did we conduct an updated risk assessment?

    While not required by or conducted as part of our GACT analysis,
one of the tasks we performed for our own purposes was to update the
risk analysis we performed when we promulgated Subpart W in 1989. We
performed a comparison between the 1989 risk assessment and current
risk assessment approaches, focusing on the adequacy and the
appropriateness of the original assessments. We did this for
informational purposes only and not for or as part of our GACT
analysis. Instead, we prepared this updated risk assessment because we
wanted to demonstrate that even using updated risk analysis procedures
(i.e. using procedures updated from those used in the 1980s), the
existing radon flux standard appears to be protective of the public
health and the environment. We did this by using the information we
collected to perform new risk assessments for existing facilities, as
well as two idealized ``generic'' sites, one located in the eastern
half of the United States and one located in the southwest United
States. (These two model sites do not exist. They are idealized using
representative features

of mills in differing climate and geography). This information has been
collected into one document \23\ that has been placed in the docket
(EPA-HQ-OAR-2008-0218-0087) for this proposed rulemaking.
---------------------------------------------------------------------------

    \23\ Technical and Regulatory Support to Develop a Rulemaking to
Potentially Modify the NESHAP Subpart W Standard for Radon Emissions
from Operating Uranium Mills (40 CFR 61.250).
---------------------------------------------------------------------------

    As part of this work, we evaluated various computer models that
could be used to calculate the doses and risks due to the operation of
conventional and ISL uranium recovery facilities, and selected CAP88 V
3.0 for use in this analysis. CAP88 V 3.0 was developed in 1988 from
the AIRDOS, RADRISK, and DARTAB computer programs, which had been
developed for the EPA at the Oak Ridge National Laboratory (ORNL).
    CAP88 V 3.0, which stands for ``Clean Air Act Assessment Package-
1988 version 3.0,'' is used to demonstrate compliance with the NESHAP
requirements applicable to radionuclides. CAP88 V 3.0 calculates the
doses and risk to a designated receptor as well as to the surrounding
population. Exposure pathways evaluated by CAP88 V 3.0 are: inhalation,
air immersion, ingestion of vegetables, meat, and milk, and ground
surface exposure. CAP88 V 3.0 uses a modified Gaussian plume equation
to estimate the average dispersion of radionuclides released from up to
six emitting sources. The sources may be either elevated stacks, such
as a smokestack, or uniform area sources, such as the surface of a
uranium byproduct material impoundment. Plume rise can be calculated
assuming either a momentum or buoyant-driven plume.
    At several sites analyzed in this evaluation only site-wide
releases of radon were available to us. This assessment was limited by
the level of detail provided by owners and operators of uranium
recovery facilities. In instances where more specific site data were
available, site-wide radon releases were used as a bounding estimate.
Assessments are done for a circular grid of distances and directions
for a radius of up to 80 kilometers (50 miles) around the facility. The
Gaussian plume model produces results that agree with experimental data
as well as any comparable model, is fairly easy to work with, and is
consistent with the random nature of turbulence. A description of CAP88
V 3.0 and the computer models upon which it is based is provided in the
CAP88 V 3.0 Users Manual.\24\
---------------------------------------------------------------------------

    \24\ http://www.epa.gov/radiation/assessment/CAP88 V 3.0/
index.html.
---------------------------------------------------------------------------

    The uranium recovery facilities that we analyzed included three
existing conventional mills (Cotter, White Mesa and Sweetwater), five
operating ISL operations (the Alta Mesa project in Brooks County,
Texas; the Crow Butte Operation in Dawes County, Nebraska; the Hobson/
La Palangana Operation in South Texas; the Willow Creek (formerly
Christensen Ranch/Irigaray Ranch) Operation in Wyoming; and the Smith
Ranch-Highland Operation in Converse County, Wyoming), and two generic
sites assumed for the location of conventional mills (we chose
conventional mills because we believe they have the potential for
greater radon emissions). One generic site was modeled in the southwest
United States (Western Generic) while the other was assumed to be
located in the eastern United States (Eastern Generic).\25\ An Eastern
generic site was selected for the second generic site to accommodate
the recognition that a number of uranium recovery facilities are
expected to apply for construction licenses in the future, and to
determine potential risks in geographic areas of the U.S. that
customarily have not hosted uranium recovery facilities. For this
assessment the conventional mills we were most interested in were the
White Mesa mill and the Sweetwater mill. (The Shootaring Canyon mill
was not analyzed, because the impoundment is very small and is soil
covered, and the Cotter facility is now in closure). These conventional
mills are either in operation or standby and are subject to the flux
standard of 20 pCi/m\2\/sec. The risk analyses performed for these two
mills showed that the maximum lifetime cancer risks from radon
emissions from the White Mesa impoundments were 1.1 x 10-4
while the maximum lifetime cancer risks from radon associated with the
impoundments at the Sweetwater mill were 2.4 x 10-5. As we
indicated in our original 1989 risk assessment, in protecting public
health, EPA strives to provide the maximum feasible protection by
limiting lifetime cancer risk from radon exposure to approximately 1 in
10,000 (i.e., 10-4).\26\ The analyses also estimated that
the total cancer risk to the populations surrounding all ten modeled
uranium sites (i.e., total cancer fatalities) is between 0.0015 and
0.0026 fatal cancers per year, or approximately 1 case every 385 to 667
years for the 4 million persons living within 80 km of the uranium
recovery facilities. Similarly, the total cancer incidence for all ten
modeled sites is between 0.0021 and 0.0036 cancers per year, or
approximately 1 case every 278 to 476 years. The analyses are described
in more detail in the background document generated for this
proposal.\27\ As stated above, we performed this risk assessment for
informational purposes only. The risk assessment was not required or
considered during our analysis for proposing GACT standards for uranium
recovery facilities (e.g., conventional impoundments, non-conventional
impoundments or heap leach piles).
---------------------------------------------------------------------------

    \25\ There is a potential in the future for uranium recovery in
areas like south-central Virginia.
    \26\ See 54 FR 51656
    \27\ All risks are presented as LCF risks. If it is desired to
estimate the morbidity risk, simply multiply the LCF risk by 1.39.
For a more detailed analysis of cancer mortality and morbidity,
please see the Background Information Document, Docket number EPA-
HQ-OAR-0218-0087.
---------------------------------------------------------------------------

III. Summary of the Proposed Requirements

    We are proposing to revise Subpart W to include requirements we
have identified that are generally available for controlling radon
emissions in a cost-effective manner, and are not currently included in
Subpart W. Specifically, we are proposing to require that non-
conventional impoundments and heap leach piles must maintain minimum
liquid levels to control their radon emissions from these affected
sources.
    Additionally, we are revising Subpart W to propose GACT standards
for the affected sources at conventional uranium mills, ISL facilities
and heap leach facilities. Given the evolution of uranium recovery
facilities over the last 20 years, we believe it is appropriate to
revise Subpart W to tailor the requirements of the rule to the
different types of facilities in existence at this time. We are
therefore proposing to revise Subpart W to add appropriate definitions,
standards and other requirements that are applicable to HAP emissions
at these uranium recovery facilities.
    Our experience with ensuring that uranium recovery facilities are
in compliance with Subpart W also leads us to propose three more
changes. First, we are proposing to remove certain monitoring
requirements that we believe are no longer necessary for demonstrating
compliance with the proposed GACT standards. Second, we are proposing
to revise certain definitions so that owners and operators clearly
understand when Subpart W applies to their facility. Third, we are
proposing to clarify what specific liner

requirements must be met under Subpart W.\28\
---------------------------------------------------------------------------

    \28\ Under its CAA authority, EPA requires facilities subject to
Subpart W to build impoundments in a manner that complies with the
requirements found in 40 CFR 192. As a matter of convenience, EPA
cross-references the part 192 requirements in Subpart W instead of
copying them directly into Subpart W. This cross-referencing
convention is often used in rulemakings.
---------------------------------------------------------------------------

    Taken altogether, the proposed revisions to Subpart W are
appropriate for updating, clarifying and strengthening the management
of radon emissions from the uranium byproduct material generated at
uranium recovery facilities.

A. What are the affected sources?

    Today we are proposing to revise Subpart W to include requirements
for affected sources at three types of operating uranium recovery
facilities: (1) Conventional uranium mills; (2) ISL facilities; and (3)
heap leach facilities. The affected sources at these uranium recovery
facilities include conventional impoundments, non-conventional
impoundments where tailings are contained in ponds and covered by
liquids (examples of these affected sources are evaporation or holding
ponds that may exist at conventional mills, ISL facilities and heap
leach facilities), and heap leach piles. The proposed GACT standards
and the rationale for these proposed standards are discussed below and
in Section IV. We request comment on all aspects of these proposed
requirements.

B. What are the proposed requirements?

1. Conventional Impoundments
    In the 1989 promulgation of Subpart W we created two work practice
standards, phased disposal and continuous disposal, for uranium
tailings impoundments designed and constructed after December 15, 1989.
The work practice standards, which limit the exposed area and/or number
of conventional impoundments at a uranium recovery facility, require
that these impoundments be no larger than 40 acres (for phased
disposal) or 10 uncovered acres (for continuous disposal). We also
limited the number of conventional impoundments operating at any one
time to two. We took this approach because we recognized that the radon
emissions from very large conventional impoundments could impose
unacceptable health effects if the piles were left dry and uncovered.
The 1989 promulgation also included the requirements in 40 CFR
192.32(a), which include design and construction requirements for the
impoundments as well as requirements for prevention and mitigation of
ground-water contamination.
    As discussed earlier, we no longer believe that a distinction needs
to be made for conventional impoundments based on the date when they
were designed and/or constructed. We believe that the existing
conventional impoundments at both the Shootaring Canyon and Sweetwater
facilities can meet the work practice standards in the current Subpart
W regulation. The conventional impoundments at both these facilities
are less than 40 acres in area and are synthetically lined as per the
requirements in 40 CFR 192.32(a)(1). The existing cell 3 at the White
Mesa mill will undergo closure in 2014 and will be replaced with the
impoundments currently under construction that meet the phased disposal
work practice standard. Therefore, there is no reason not to subject
these older impoundments to the work practice standards required for
impoundments designed or constructed after December 15, 1989. By
incorporating these impoundments under the work practices provision of
Subpart W, it is no longer necessary to require radon flux monitoring,
and we are proposing to eliminate that requirement.
    The proposed elimination of the monitoring requirement in 40 CFR
61.253 applies only to those facilities currently subject to the radon
flux standard in 40 CFR 61.252(a), which applies to only the three
conventional impoundments in existence prior to the original
promulgation of Subpart W on December 15, 1989. While we are proposing
to eliminate the radon monitoring requirement for these three
impoundments under Subpart W, this action does not relieve the owner or
operator of the uranium recovery facility of the monitoring and
maintenance requirements of their operating license issued by the NRC
or its Agreement States. These requirements are found at 10 CFR Part
40, Appendix A, Criterion 8 and 8A. Additionally, NRC, through its
Regulatory Guide 4.14, may also recommend incorporation of radionuclide
air monitoring at operating facility boundaries.
    Further, when the impoundments formally close they are subject to
the radon monitoring requirements of 40 CFR 192.32(a)(3), also under
the NRC licensing requirements.
    From a cost standpoint, by not requiring radon monitoring we expect
that for all three sites the total annual average cost savings would be
$29,200, with a range from about $21,000 to $37,000. More details on
economic costs can be found in Section IV.B of this preamble.
    For the proposed rule we also evaluated the requirements of 40 CFR
192.32(a) as they pertain to the Subpart W standards. The requirements
of 40 CFR 192.32(a) are included in the NRC's regulations and are
reviewed for compliance by NRC during the licensing process for a
uranium recovery facility. We determined that the requirements at 40
CFR 192.32(a)(1), which reference the RCRA requirements for design and
operation of surface impoundments at 40 CFR 264.221, are the only
requirements necessary for EPA to incorporate for Subpart W, as they
are effective methods of containing tailings and protecting ground
water while also limiting radon emissions. This liner requirement,
described earlier in this preamble, remains in use for the permitting
of hazardous waste land disposal units under RCRA. The requirements at
40 CFR 192.32(a)(1) contain safeguards to allow for the placement of
tailings and yet provide an early warning system in the event of a leak
in the liner system. We are therefore proposing to retain the two work
practice standards and the requirements of 40 CFR 192.32(a)(1) as GACT
for conventional impoundments because these methods for limiting radon
emissions while also protecting ground water have proven effective for
these types of impoundments.
2. Non-Conventional Impoundments Where Tailings Are Contained in Ponds
and Covered by Liquids
    Today we are proposing a GACT standard specifically for non-
conventional impoundments where uranium byproduct materials are
contained in ponds and covered by liquids. Common names for these
structures may include, but are not limited to, impoundments and
evaporation or holding ponds. These affected sources may be found at
any of the three types of uranium recovery facilities.
    These units meet the existing applicability criteria in 40 CFR
61.250 to classify them for regulation under Subpart W. The holding or
evaporation ponds located at conventional mills, ISL facilities and
potentially heap leach facilities contain uranium byproduct material,
either in solid form or dissolved in solution, and therefore their
emissions are regulated under Subpart W. As defined at 40 CFR
61.251(g), uranium byproduct material or tailings means the waste
produced by the extraction or concentration of uranium from any ore
processed primarily for its source material content.

Therefore, emissions for the ponds at uranium recovery facilities that
contain either uranium byproduct material in solid form or
radionuclides dissolved in liquids are regulated under Subpart W. Today
we are again stating that determination and proposing a GACT standard
specifically for these impoundments.
    Evaporation or holding ponds, while sometimes smaller in area than
conventional impoundments, perform a basic task. They hold uranium
byproduct material until it can be disposed. Our survey of existing
ponds shows that they contain liquids, and, as such, this general
practice has been sufficient to limit the amount of radon emitted from
the ponds, in many cases, to almost zero. Because of the low potential
for radon emissions from these impoundments, we do not believe it is
necessary to monitor them for radon emissions. We have found that as
long as approximately one meter of liquid is maintained in the pond,
the effective radon emissions from the pond are so low that it is
difficult to determine whether there is any contribution above
background radon values. EPA has stated in the Final Rule for Radon-222
Emissions from Licensed Uranium Mill Tailings: Background Information
Document (August, 1986):

    ``Recent technical assessments of radon emission rates from
tailings indicate that radon emissions from tailings covered with
less than one meter of water, or merely saturated with water, are
about 2% of emissions from dry tailings. Tailings covered with more
than one meter of water are estimated to have a zero emissions rate.
The Agency believes this calculated difference between 0% and 2% is
negligible. The Agency used an emission rate of zero for all
tailings covered with water or saturated with water in estimating
radon emissions.''

    Therefore, we are proposing as GACT that these impoundments meet
the design and construction requirements of 40 CFR 192.32(a)(1), with
no size/area restriction, and that during the active life of the pond
at least one meter of liquid be maintained in the pond.
    We are also proposing that no monitoring be required for this type
of impoundment. We have received information and collected data that
show there is no acceptable radon flux test method for a pond holding a
large amount of liquid. (Method 115 does not work because a solid
surface is needed to place the large area activated carbon canisters
used in the Method). Further, even if there was an acceptable method,
we recognize that radon emissions from the pond would be expected to be
very low because the liquid acts as an effective barrier to radon
emissions; given that radon-222 has a very short half-life (3.8 days),
there simply is not enough time for most of the radon produced by the
solids or from solution to migrate to the water surface and cross the
water/air interface before decaying(EPA-HQ-OAR-2008-0218-0087). It
therefore appears that monitoring at these ponds is not necessary for
demonstrating compliance with the proposed standards. We do, however,
ask for comment and supporting information on three issues: (1) Whether
these impoundments need to be monitored with regard to their radon
emissions, and why; (2) whether these impoundments need to be monitored
to ensure at least one meter of liquid is maintained in the pond at all
times, and (3) if these impoundments do need monitoring, what methods
could a facility use (for example, what types of radon collection
devices, or methods to measure liquid levels) at evaporation or holding
ponds.
3. Heap Leach Piles
    The final impoundment category for which we are proposing GACT
standards is heap leach piles. We are proposing to require that heap
leach piles meet the phased disposal work practice standard set out in
Section III B. 1. of this preamble (which limits an owner/operator to
no more than two operating heap leach piles of no more than 40 acres
each at any time) and the design and construction requirements at 40
CFR 192.32(a)(1) as GACT. We are also requiring heap leach piles to
maintain minimum moisture content of 30% so that the byproduct material
in the heap leach pile does not dry out, which would increase radon
emissions from the heap leach pile.
    As noted earlier in the preamble, there are currently no operating
uranium heap leach facilities in the United States. We are aware that
the one currently proposed heap leach facility will use the design and
operating requirements at 40 CFR 192.32(a)(1) for the design of its
heap. Since this requirement will be used at the only example we have
for a heap leach pile, it (design and operating requirements at 40 CFR
192.32(a)(1)), along with the phased disposal work practice standard
(limiting the number and size of heap leach piles), will be the
standards that we propose as GACT for heap leach piles. The premise is
that the operator of a heap would not want to lose any of the uranium-
bearing solution; thus, it is cost effective to maintain a good liner
system so that there will be no leakage and ground water will be
protected. Also, use of the phased disposal work practice standard will
limit the amount of exposed uranium byproduct material that would be
available to emit radon. If we assume that uranium ore (found in the
heap leach pile) and the resultant leftover byproduct material after
processing emit radon at the same rate as uranium byproduct material in
a conventional impoundment (a conservative estimate), we can also
assume that the radon emissions will be nearly the same as two 40 acre
conventional impoundments.
    We recognize that owners and operators of conventional impoundments
also limit the amount of radon emitted by keeping the tailings in the
impoundments covered, either with soil or liquids. At the same time,
however, we recognize that keeping the uranium byproduct material in
the heap in a saturated or near-saturated state (in order to reduce
radon emissions) is not a practical solution as it would be at a
conventional tailings impoundment. In the definitions at 40 CFR
61.251(c) we have defined ``dewatered'' tailings as those where the
water content of the tailings does not exceed 30% by weight. We are
proposing today to require operating heaps to maintain moisture content
of greater than 30% so that the byproduct material in the heap is not
allowed to become dewatered which would allow more radon emissions. We
are specifically asking for comment on the amount of liquid that should
be required in the heap, and whether the 30% figure is a realistic
objective. We are also asking for comments on precisely where in the
heap leach pile this requirement must be met. The heap leach pile may
not be evenly saturated during the uranium extraction process. The
sprayer/drip system commonly used on the top of heap leach piles
usually results in a semi-saturated moisture condition at the top of
the pile, since flow of the lixiviant is not uniformly spread across
the top of the pile. As downward flow continues, the internal areas of
the pile become saturated. We are requesting information and comment on
where specifically in the pile the 30% moisture content should apply.

C. What are the monitoring requirements?

    As the rule currently exists, only mills with existing conventional
impoundments in operation on or prior to December 15, 1989, are
currently required to monitor to ensure compliance with the radon flux
standard. The reason for this is because at the time of promulgation of
the 1989 rule, EPA stated that no flux monitoring would be required for
new impoundments because the proposed

work practice standards would be effective in reducing radon emissions
from operating impoundments by limiting the amount of tailings exposed
(54 FR 51681). Since we have now determined that existing older
conventional impoundments can meet one of the two work practice
standards, we are proposing to eliminate the radon flux monitoring
requirement.
    In reviewing Subpart W we looked into whether we should extend
radon monitoring to all affected sources constructed and operated after
1989 so that the monitoring requirement would apply to all conventional
impoundments, non-conventional impoundments and heap leach piles
containing uranium byproduct materials. We also reviewed how this
requirement would apply to facilities where Method 115 is not
applicable, such as at impoundments totally covered by liquids. We
concluded that the original work practice standards (now proposed as
GACT) continue to be an effective practice for the limiting of radon
emissions from conventional impoundments and from heap leach piles. We
also concluded that by maintaining an effective water cover on non-
conventional impoundments the radon emissions from those impoundments
are so low as to be difficult to differentiate from background radon
levels at uranium recovery facilities. Therefore, we are proposing
today that it is not necessary to require radon monitoring for any
affected sources regulated under Subpart W. We seek comment on our
conclusion that radon monitoring is not necessary for any of these
sources as well as on any available cost-effective options for
monitoring radon at non-conventional impoundments totally covered by
liquids.

D. What are the notification, recordkeeping and reporting requirements?

    New and existing affected sources are required to comply with the
existing requirements of the General Provisions (40 CFR part 61,
subpart A). The General Provisions include specific requirements for
notifications, recordkeeping and reporting, including provisions for
notification of construction and/or modification and startup as
required by 40 CFR 61.07, 61.08 and 61.09.
    Today we are also proposing that all affected sources will be
required to maintain certain records pertaining to the design,
construction and operation of the impoundments, both including
conventional impoundments, and nonconventional impoundments, and heap
leach piles. We are proposing that these records be retained at the
facility and contain information demonstrating that the impoundments
and/or heap leach pile meet the requirements in section 192.32(a)(1),
including but not limited to, all tests performed that prove the liner
is compatible with the material(s) being placed on the liner. For
nonconventional impoundments we are proposing that this requirement
would also include records showing compliance with the continuous one
meter of liquid in the impoundment; \29\ for heap leach piles, we are
proposing that this requirement would include records showing that the
30% moisture content of the pile is continuously maintained. Documents
showing that the impoundments and/or heap leach pile meet the
requirements in section 192.32(a)(1) are already required as part of
the pre-construction application submitted under 40 CFR 61.07, so these
records should already be available. Records showing compliance with
the one meter liquid cover requirement for nonconventional impoundments
and records showing compliance with the 30% moisture level required in
heap leach piles can be created and stored during the daily inspections
of the tailings and waste retention systems required by the NRC (and
Agreement States) under the inspection requirements of 10 CFR 40,
Appendix A, Criterion 8A.
---------------------------------------------------------------------------

    \29\ The one meter liquid requirement pertains to having one
meter of liquid cover any and all solid byproduct material. We do
not anticipate a large quantity of solid byproduct material in these
nonconventional impoundments (EPA-HQ-OAR-2008-0218-0088).
---------------------------------------------------------------------------

    Because we are proposing new record-keeping requirements for
uranium recovery facilities, we are required by the Paperwork Reduction
Act (PRA) to prepare an estimate of the burden of such record-keeping
on the regulated entity, in both cost and hours necessary to comply
with the requirements. We have submitted the Information Collection
Request (ICR) containing this burden estimate and other supporting
documentation to the Office of Management and Budget (OMB). See Section
VII.B for more discussion of the PRA and ICR.
    We believe the record-keeping requirements proposed today will not
create a significant burden for operators of uranium recovery
facilities. As described earlier, we are proposing to require retention
of three types of records: (1) Records demonstrating that the
impoundments and/or heap leach pile meet the requirements in section
192.32(a)(1) (e.g. the design and liner testing information); (2)
records showing that one meter of water is maintained to cover the
byproduct material stored in nonconventional impoundments; and (3)
records showing that heap leach piles maintain a moisture content of at
least 30%.
    Documents demonstrating that the affected sources comply with
section 192.32(a)(1) requirements are necessary for the facility to
obtain regulatory approval from NRC (or an NRC Agreement State) and EPA
to construct and operate the affected sources (this includes any
revisions during the period of operations). Therefore, these records
will exist independent of Subpart W requirements and will not need to
be continually updated as a result of this record-keeping requirement
in Subpart W; however, we are proposing to include this record-keeping
requirement in Subpart W to require that the records be maintained at
the facility during its operational lifetime (in some cases the records
might be stored at a location away from the facility, such as corporate
offices). This might necessitate creating copies of the original
records and providing a location for storing them at the facility.
    Keeping a record to provide confirmation that water to a depth of
one meter is maintained above the byproduct material stored in
nonconventional impoundments should also be relatively straightforward.
This would involve placement of a measuring device or devices in or at
the edge of the impoundment to allow observation of the water level
relative to the level of byproduct material in the impoundment. Such
devices need not be highly technical and might consist of, for example,
measuring sticks with easily-observable markings placed at various
locations, or marking the sides of the impoundment to illustrate
different water depths. As noted earlier, NRC and Agreement State
licenses require operators to inspect the facility on a daily basis.
Limited effort should be necessary to make observations of water depth
and record the information in inspection log books that are already
kept on site and available to inspectors.
    Similarly, daily inspections would provide a mechanism for
recording moisture content of heap leach piles. However, because no
heap leach facilities are currently operating, there is more
uncertainty about exactly how the operator will determine that the heap
has maintained a 30% moisture content. As discussed in more detail in
Section IV.E.4 of this preamble, soil moisture probes are readily
available and could be used for this purpose. Such probes could be
either left in the heap leach pile, placed at locations that provide a

representative estimate for the heap as a whole, or facility personnel
could use handheld probes to collect readings. The facility might also
employ mass-balance estimates to provide a further check on the data
collected.
    We estimate the burden in hours and cost for uranium recovery
facilities to comply with the proposed recordkeeping requirements are
as follows:

 Table 1--Burden Hours and Costs for Proposed Recordkeeping Requirements
                   [Annual figures except where noted]
------------------------------------------------------------------------
                   Activity                        Hours        Costs
------------------------------------------------------------------------
Maintaining Records for the section                     *20     * $1,360
 192.32(a)(1) requirements....................
Verifying the one meter liquid requirement for          288       12,958
 nonconventional impoundments.................
Verifying the 30% moisture content at heap            2,068       86,548
 leach piles using multiple soil probes.......
------------------------------------------------------------------------
* These figures represent a one-time cost to the facility.

    Burden levels for heap leach piles are most uncertain because they
depend on the chosen method of measurement (e.g., purchasing and
maintaining multiple probes or a smaller number of handheld units) as
well as the personnel training involved (e.g., a person using a
handheld unit will likely need more training than someone who is simply
recording readings from already-placed probes). We request comment on
our estimates of burden, as well as suggestions of methods that could
readily and efficiently be used to collect the required information.
More discussion of the ICR and opportunities for comment may be found
in Section VII.B.

E. When must I comply with these proposed standards?

    All existing affected sources subject to this proposed rule would
be required to comply with the rule requirements upon the date of
publication of the final rule in the Federal Register. To our
knowledge, there is no existing operating uranium recovery facility
that would be required to modify its affected sources to meet the
requirements of the final rule; however, we request any information
regarding affected sources that would not meet these requirements. New
sources would be required to comply with these rule requirements upon
the date of publication of the final rule in the Federal Register or
upon startup of the facility, whichever is later.

IV. Rationale for This Proposed Rule

A. How did we determine GACT?

    As provided in CAA section 112(d)(5), we are proposing standards
representing GACT for this area source category. In developing the
proposed GACT standards, we evaluated the control technologies and
management practices that are available to reduce HAP emissions from
the affected sources and identified those that are generally available
and utilized by operating uranium recovery facilities.
    As noted in Section II.F., for this proposal we solicited
information on the available controls and management practices for this
area source category using written facility surveys (surveys authorized
by section 114(a) of the CAA), reviews of published literature, and
reviews of existing facilities (EPA-HQ-OAR-0218-0066). We also held
discussions with trade association and industry representatives and
other stakeholders at various public meetings.\30\ Our determination of
GACT is based on this information. We also considered costs and
economic impacts in determining GACT (See Section VI.).
---------------------------------------------------------------------------

    \30\ See http://www.epa.gov/radiation/neshaps/subpartw/rulemaking-activity.html for a list of presentations made at public
meetings held by EPA and at various conferences open to the public.
---------------------------------------------------------------------------

    We identified two general management practices that reduce radon
emissions from affected sources. These general management practices are
currently being used at all existing uranium recovery facilities.
First, limiting the area of exposed tailings in conventional
impoundments limits the amount of radon that can be emitted. The work
practice standards currently included in Subpart W require owners and
operators of affected sources to implement this management practice by
either limiting the number and area of existing, operating impoundments
or covering dewatered tailings to allow for no more than 10 acres of
exposed tailings. This is an existing requirement of Subpart W and of
the NRC licensing requirements; hence, owners and operators of uranium
recovery facilities are already incurring the costs associated with
limiting the area of conventional impoundments (and as proposed, heap
leach piles) to 40 acres or less (as well as no more than two
conventional impoundments in operation at any one time), or limiting
the area of exposed tailings to no more than 10 acres.
    Second, covering uranium byproduct materials with liquids is a
general management practice that is an effective method for limiting
radon emissions. This general management practice is often used at
nonconventional impoundments, which, as stated earlier, are also known
as evaporation or holding ponds. These nonconventional impoundments
also contain byproduct material, and thus their HAP emissions are
regulated under Subpart W. They are also regulated under the NRC
operating license. While they hold mostly liquids, they are still
designed and constructed in the manner of conventional impoundments,
meaning they meet the requirements of section 192.32(a)(1). While this
management practice of covering uranium byproduct materials in
impoundments with liquids is not currently required under Subpart W,
facilities using this practice have generally shown its effectiveness
in reducing emissions in both conventional impoundments (that make use
of phased disposal) and nonconventional impoundments (i.e. holding or
evaporation ponds). We are therefore proposing to require the use of
liquids in nonconventional impoundments as a way to limit radon
emissions.
    Therefore, after review of the available information and from the
evidence we have examined, we have determined that a combination of the
management practices listed above will be effective in limiting radon
emissions from this source category, and will do so in a cost effective
manner. We also believe that since heap leach piles are in many ways
similar to the design of conventional impoundments, the same
combination of work practices (limitation to no more than two operating
heap leach piles, each one no more than 40 acres) will limit radon
emissions in heap leach piles. We discuss our reasons supporting these
conclusions in more detail in Section IV.B.

B. Proposed GACT Standards for Operating Mill Tailings

1. Requirements at 40 CFR 192.32(a)(1)
    As an initial matter, we determined that the requirements at 40 CFR
192.32(a)(1), which reference the RCRA requirements for the design and
construction of liners at 40 CFR 264.221, continue to be an effective
method of containment of tailings for all types of affected sources
(EPA-HQ-OAR-2008-0218-0015). The liner requirements, described earlier
in this document, remain in use for the permitting of hazardous waste
land disposal units under RCRA. Because of the requirement for nearly
impermeable boundaries between the tailings and the subsurface, and the
requirement for leak detection between the liners, we have determined
that the requirements contain enough safeguards to allow for the
placement of tailings and also provide an early warning system in the
event of a leak in the liner system (EPA-HQ-OAR-2008-0218-0015). For
this reason we are proposing to require as GACT that conventional
impoundments, non-conventional impoundments and heap leach piles all
comply with the liner requirements in 40 CFR 192.32(a)(1). Previously,
Subpart W contained this requirement but included a more general
reference to 40 CFR 192.32(a); we are proposing to replace that general
reference with a more specific reference to 40 CFR 192.32(a)(1) to
narrow the requirements under this proposed rule to only the design and
construction requirements for the liner of the impoundment contained in
40 CFR 192.32(a)(1).
    The estimated average cost of the liner requirement for each type
of impoundment at uranium recovery facilities is listed in the table
below (EPA-HQ-OAR-2008-0218-0087):

                                         Table 2--Estimated Liner Costs
----------------------------------------------------------------------------------------------------------------
                      Table 2--Proposed GACT standards costs per pound of U[ihel3]O[ihel8]
-----------------------------------------------------------------------------------------------------------------
                                                                         Unit cost ($/lb U[ihel3]O[ihel8])
                                                                 -----------------------------------------------
                                                                   Conventional         ISL         Heap Leach
----------------------------------------------------------------------------------------------------------------
GACT--Double Liners for Nonconventional Impoundments............          $1.04           $3.07          $0.22
GACT--Maintaining 1 Meter of Water in Nonconventional                      0.013           0.010          0.0010
 Impoundments...................................................
GACT--Liners for Heap Leach Piles...............................  ..............  ..............          2.01
GACT--Maintaining Heap Leach Piles at 30% Moisture..............  ..............  ..............          0.0043
GACTs--Total for All Four.......................................           1.05            3.08           2.24
----------------------------------------------------------------------------------------------------------------

    Table 2 presents a summary of the unit cost (per pound of
U3O8) for implementing each GACT at each of the
three types of uranium recovery facilities. In addition to presenting
the GACT costs individually, Table 2 presents the total unit cost to
implement all relevant GACTs at each type of facility.
    Based on the Table 2, implementing all four GACTs would result in
unit cost (per pound of U3O8) increases of about
2%, 6%, and 5% at conventional mills, ISL, and heap leach type uranium
recovery facilities, respectively.
    In making these cost estimates, we have assumed the following: (1)
A conventional impoundment is no larger than 40 acres in size, which is
the maximum size allowed for the phased disposal option; (2) a
nonconventional impoundment is no larger than 80 acres in size (the
largest size we have seen); and (3) a heap leach pile is no larger than
40 acres in size (again, the maximum size allowed under the phased
disposal work practice standard, although as with conventional
impoundments the owner or operator is limited to two of these affected
sources to be in operation at any time).
    We do not have precise data for the costs associated with the liner
requirements at conventional impoundments using the continuous disposal
work practice standard because currently none exist, but a reasonable
maximum approximation would be the costs for the 80 acre
nonconventional impoundment, since it is the largest we have seen. We
believe that no additional costs would be incurred for building a
conventional impoundment that will use the continuous disposal option
above what we estimated for building a nonconventional impoundment but
we ask for comment on whether this assumption is reasonable. We also
ask for data on the costs of building a conventional impoundment using
continuous disposal, and how those costs would differ from the
estimates provided above, or whether the costs we have listed for
building a conventional impoundment using phased disposal are a
reasonable approximation of the costs for building a conventional
impoundment using continuous disposal.
    These liner systems are already required by 40 CFR 192.32(a)(1),
which, as explained above, are requirements promulgated by EPA under
UMTRCA that are incorporated into NRC regulations and implemented and
enforced by NRC and NRC Agreement States through their licensing
requirements. Therefore, we are not placing any additional liner
requirements on facilities or requiring them to incur any additional
costs to build their conventional or nonconventional impoundments or
heap leach piles above and beyond what an owner or operator of these
impoundments must already incur to obtain an NRC or NRC Agreement State
license.
    The liner systems we are proposing that heap leach piles must use
are the same as those used for conventional and nonconventional
impoundments. We estimate that the average costs associated with the
construction of a 40 acre liner that complies with 40 CFR
192.32(a)(1)is approximately $15.3 million. When compared to the
baseline capital costs associated with the facility (estimated at $356
million)(EPA-HQ-OAR-2008-0218-0087), the costs for constructing this
type of liner system per facility is about 4% of the total baseline
capital costs of a heap leach pile facility (EPA-HQ-OAR-2008-0218-
0087).\31\
---------------------------------------------------------------------------

    \31\ For our purposes, baseline conditions are defined as a
reference point that reflects the world without the proposed
regulation. It is the starting point for conducting an economic
analysis of the potential benefits and costs of a proposed
regulation. The defined baseline influences first the level of
emissions expected without regulatory intervention. It thereby also
influences the projected level of emissions reduction that may be
achieved as a consequence of the proposed regulation. Baselines have
no standard definition besides the fact that they simply provide a
reference scenario against which changes in economic and
environmental conditions (in this case radon emissions) can be
measured. In some instances, baselines have been established based
on the assumption that economic, environmental and/or other
conditions will continue on the present path or trend, purely as
time dependant extensions of presently observed patterns. In other
instances, baselines are derived from elaborate modeling
projections. Because in all cases their purpose is to project a view
of the world without the proposed regulatory intervention, baselines
are sometimes termed ``do nothing'' or ``business as usual''
scenarios.

---------------------------------------------------------------------------

2. Conventional Impoundments
    In the 1989 promulgation of Subpart W we required new conventional
impoundments to comply with one of two work practice standards, phased
disposal or continuous disposal. These work practice standards contain
specific limits on the exposed area and/or number of operating
conventional impoundments to limit radon emissions because we
recognized that radon emissions from very large impoundments could
impose unacceptable health effects if the piles were left dry and
uncovered. We are proposing as the GACT standard that all conventional
impoundments--both existing impoundments and new impoundments--comply
with one of the two work practice standards, phased disposal or
continuous disposal, because these methods for limiting radon emissions
by limiting the area of exposed tailings continue to be effective
methods for reducing radon emissions from these impoundments (reference
EPA 520-1-86-009, August 1986). We are proposing that existing
impoundments also comply with one of the two work practice standards
because, as discussed earlier, we no longer believe that a distinction
needs to be made for conventional impoundments based on the date when
they were designed and/or constructed.
    We are also not aware of any conventional impoundments either in
existence or planned that use any other technologies or management
practices to reduce radon emissions. Operators continue to use the
general management practices discussed above for reducing radon
emissions from their conventional impoundments, i.e., limiting the size
and/or number of the impoundments, and covering the tailings with soil
or keeping the tailings wet. These management practices form the basis
of the work practice standards for conventional impoundments and
continue to be very effective methods for limiting the amount of radon
released to the environment.
    These work practice standards are a cost-effective method for
reducing radon emissions from conventional impoundments. In addition,
the liner requirements for conventional impoundments are also required
by the NRC in their licensing requirements at 10 CFR part 40.
Therefore, we are proposing that GACT for conventional impoundments
will be the same work practice standards as were previously included in
Subpart W.
3. Non-Conventional Impoundments Where Tailings Are Contained in Ponds
and Covered by Liquids
    Today we are proposing a GACT standard specifically for use by any
operating uranium recovery facility that has one or more non-
conventional impoundments at its facility (i.e., those impoundments
where tailings are contained in ponds and covered by liquids). Common
names for these structures may include, but are not limited to,
impoundments, evaporation ponds and holding ponds. These ponds contain
uranium byproduct material and the HAP emissions are regulated by
Subpart W.
    Industry has argued in preambles to responses to the CAA section
114(a) letters \32\ and elsewhere that Subpart W does not, and was
never meant to, include these types of evaporation or holding ponds
under the Subpart W requirements. Industry has asserted that the
original Subpart W did not specifically reference evaporation or
holding ponds but was regulating only conventional mill tailings
impoundments. They argue that the ponds are temporary because they hold
very little solid material but instead hold mostly liquids containing
dissolved radionuclides (which emit very little radon), and at the end
of the facility's life they are drained, and any solid materials, along
with the liner system, are disposed in a properly licensed conventional
impoundment.
---------------------------------------------------------------------------

    \32\ http://www.epa.gov/radiation/neshaps/subpartw/rulemaking-activity.html.
---------------------------------------------------------------------------

    EPA has consistently maintained that these non-conventional
impoundments meet the existing applicability criteria for regulation
under Subpart W. As defined at 40 CFR 61.251(g), uranium byproduct
material or tailings means the waste produced by the extraction or
concentration of uranium from any ore processed primarily for its
source material content. The holding or evaporation ponds located at
conventional mills, ISL facilities and potentially heap leach
facilities contain uranium byproduct materials, either in solid form or
dissolved in solution, and therefore their HAP emissions are regulated
under Subpart W. Today we reiterate that position and are proposing a
GACT standard more specifically tailored for these types of
impoundments.
    We are proposing that these non-conventional impoundments (the
evaporation or holding ponds) must maintain a liquid level in the
impoundment of no less than one meter at all times during the operation
of the impoundment. Maintaining this liquid level will ensure that
radon-222 emissions from the uranium byproduct material in the pond are
minimized. We are also proposing that there is no maximum area
requirement for the size of these ponds since the chance of radon
emissions is small. Our basis for this determination is that radon
emissions from the pond will be expected to be very low since the
liquid in the ponds acts as an effective barrier to radon emissions;
given that radon-222 has a very short half-life (3.8 days), there
simply is not enough time for approximately 98% of the radon produced
by the solids or from the solution to migrate to the water surface and
cross the water/air interface before decaying.
    By requiring a minimum of one meter of water in all nonconventional
impoundments that contain uranium byproduct material, the release of
radon from these impoundments would be greatly reduced. Nielson and
Rogers (1986) present the following equation for calculating the radon
attenuation:
[GRAPHIC] [TIFF OMITTED] TP02MY14.072

Where:

A = Radon attenuation factor (unit less)
[lambda] = Radon-222 decay constant (sec-\1\)
= 2.1x10-\6\ sec-\1\
D = Radon diffusion coefficient (cm\2\/sec)
= 0.003 cm\2\/sec in water
d = Depth of water (cm)
= 100 cm

    The above equation indicates that the attenuation of radon
emanation by water (i.e., the amount by which a water cover will
decrease the amount of radon emitted from the impoundment) depends on
how quickly radon-222 decays, how quickly radon-222 can move through
water (the diffusion coefficient), and the thickness of the layer of
water.\33\ Solving the above equation shows that one meter of water has
a radon attenuation factor of about 0.07. That is, emissions can be
expected to be reduced by about 93% compared to no water cover.
---------------------------------------------------------------------------

    \33\ For a detailed discussion of this topic, which includes the
effects of pond water mixing, wind and convection, please see ``Risk
Assessment Revision for 40 CFR Part 61 Subpart W-Radon Emissions
from Operating Mill Tailings, Task 5 Radon Emission from Evaporation
Ponds,''(EPA-HQ-OAR-2008-0218-0080).
---------------------------------------------------------------------------

    The benefit incurred by this requirement is that significantly less
radon will be released to the atmosphere. The amount varies from
facility to facility based on the size of the nonconventional
impoundment, but

across existing facilities radon can be expected to be reduced by
approximately 24,600 curies, a decline of approximately 93%.
    The estimated cost associated with complying with the proposed one
meter of liquid that would be required to limit the amount of radon
emissions to the air vary according to the size of the impoundment and
the geographic area in which it is located. We estimate that this
requirement will cost owners or operators of 80 acre nonconventional
impoundments between $1,042 and $9,687 per year. This value varies
according to the location of the impoundment, which will determine
evaporation rates, which determines how much replacement water will be
required to maintain the minimum amount of one meter. If the evaporated
water is not replaced by naturally occurring precipitation, then it
would need to be replaced with make-up water supplied by the
nonconventional impoundment's operator.
    The most obvious source of water is what is known as ``process
water'' from the extraction of uranium from the subsurface. Indeed,
management of this process water is one of the primary reasons for
constructing the impoundment in the first place, as the process water
contains uranium byproduct material that must also be managed by the
facility. It is possible that an operator could maintain one meter of
water in the impoundment solely through the use of process water. If
so, this would not create any additional costs for the facility as the
cost of the process water can be attributed to its use in the uranium
extraction process. However, for purposes of estimating the economic
impacts associated with our proposal, our cost estimate does not
include process water as a source of water potentially added to the
impoundment to replace water that has evaporated. Instead, we estimated
the costs of using water from other sources. This method results in the
most conservative cost estimate for compliance with the one meter
requirement.
    In performing the cost impacts for this requirement, three
potential sources of impoundment make-up water were considered: (1)
Municipal water suppliers; (2) offsite non-drinking-water suppliers;
and (3) on-site water (EPA-HQ-OAR-2008-0218-0087). Depending on the
source of water chosen, we estimate that this requirement will cost
owners or operators of nonconventional impoundments between $1,042.00
and $9,687.00 per year.\34\
---------------------------------------------------------------------------

    \34\ Municipal sources were the most expensive, with average
unit costs of $0.0033 per gallon. Offsite non-drinking water sources
were the cheapest, at $0.000069 per gallon on average. Various
references were used for the comparisons. For more detail, please
see Section 6.3.3 of the Background Information Document.
---------------------------------------------------------------------------

    This value also varies according to the size and location of the
nonconventional impoundment. Such impoundments currently range up to 80
acres in size. The requirement to maintain a minimum of one meter of
liquid in the ponds is estimated to cost approximately $0.03 per pound
of uranium produced. The annual cost of makeup water was divided by the
base case facility yellowcake annual production rate to calculate the
makeup water cost per pound of yellowcake produced (EPA-HQ-OAR-2008-
0218-0087). We conclude that this proposed requirement is a cost-
effective way to significantly reduce radon emissions from
nonconventional impoundments, and is therefore appropriate to propose
as a GACT standard for nonconventional impoundments.
4. Heap Leach Piles
    The final affected source type for which we are proposing GACT
standards is heap leach piles. While there are currently no operating
uranium heap leach facilities in the United States, we are proposing to
regulate the HAP emission at any future facilities using this type of
uranium extraction under Subpart W since the moment that uranium
extraction takes place in the heap, uranium byproduct materials are
left behind. During the process of uranium extraction on a heap, as the
acid drips through the ore, uranium is solubilized and carried away to
the collection system where it is further processed. At the point of
uranium movement out of the heap, what remains is uranium byproduct
materials as defined by 40 CFR 61.251(g). In other words, what remains
in the heap is the waste produced by the extraction or concentration of
uranium from ore processed primarily for its source material content.
Thus, Subpart W applies because uranium byproduct materials are being
generated during and following the processing of the uranium ore in the
heap.
    As a result, we are proposing GACT standards for heap leach piles.
We are proposing that these piles conform to the phased disposal work
practice standard specified for conventional impoundments in 40 CFR
61.252(a)(1)(i)(which limits the number of active heap leach piles to
two, and limits the size of each one to no more than 40 acres) and that
the moisture content of the uranium byproduct material in the heap
leach pile be greater than or equal to 30% moisture content. We believe
that the phased disposal approach can be usefully applied here because
it limits the amount of tailings that can be exposed at any one time,
which limits the amount of radon that can be emitted. The phased
disposal work practice standard is applicable for heap leach piles
because heap leach piles are expected to be managed in a manner that is
similar in many respects to conventional impoundments. Based on what we
understand about the operation of potential future heap leach
facilities, after the uranium has been removed from the heap leach
pile, the uranium byproduct material that remains would be contained in
the heap leach structure which would be lined according to the
requirements of 40 CFR 192.32(a)(1). The heap leach pile would also be
covered with soil at the end of its operational life to minimize radon
emissions.
    This is what is required to occur at conventional impoundments
using the phased disposal standard. Limiting the size of the operating
heap leach pile to 40 acres or less (and the number of operating heap
leach piles at any one time to two) has the same effect as it does on
conventional impoundments; that is, it limits the area of exposed
uranium byproduct material and therefore limits the radon emissions
from the heap leach pile. While we believe that the 40 acre limitation
is appropriate for heap leach piles, we are requesting comment on what
should be the maximum size (area) of a heap leach pile.
    We are also proposing as GACT that the heap leach pile constantly
maintain a moisture content of at least 30% by weight. By requiring a
moisture content of at least 30%, the byproduct material in the heap
leach pile will not become dewatered, and we think that the heap leach
pile will be sufficiently saturated with liquid to reduce the amount of
radon that can escape from the heap leach pile. However, we request
further information on all the chemical mechanisms in place during the
leaching operation, and whether the 30% moisture content is sufficient
for minimizing radon emissions from the heap leach pile. We also
request comment on the amount of time the 30% moisture requirement
should be maintained by a facility. We are proposing the term
``operational life'' of the facility. We are aware of several
operations that take place during the

uranium extraction process at a heap leach pile. After an initial
period of several months of allowing lixiviant to leach uranium from
the pile, the heap leach pile is allowed to ``rest,'' which enables the
geochemistry in the pile to equilibrate. At that point the heap leach
pile may be subjected to another round of extraction by lixiviant, or
it may be rinsed to flush out any remaining uranium that is in solution
in the heap leach pile. After the rinsing, the pile is allowed to drain
and a radon barrier required by 40 CFR 192.32 can be emplaced. We are
proposing that the operational life of the heap leach pile be from the
time that lixiviant is first placed on the heap leach pile until the
time of the final rinse. We believe this incorporates a majority of the
time when the heap leach pile is uncovered (no radon barrier has been
constructed over the top of the heap) and when the ability for radon to
be emitted is the greatest.
    Because there is no ``process water'' component to a heap leach
operation, as there is for an ISL, water for the heap leach pile must
be supplied from an outside source. Even if an ISL and heap leach
operation were to be located at the same site, we consider it unlikely
that an operator would use ISL process water as the basis for an acidic
heap leach solution. It is possible, in fact likely, that the solution
used in the heap will be recycled (i.e., applied to the heap more than
once), which could reduce the amount of outside water needed to some
degree, although as we discuss later in this section, it would not seem
that recycling solution would affect the overall moisture content. In
calculating the high-end costs of heap leaching, we have not included
this possibility in our estimates of economic impacts.
    The unit costs for providing liquids to a heap leach pile are
assumed to be the same as the unit costs developed for providing water
to nonconventional impoundments. In estimating the cost impacts for
this requirement, three potential sources of impoundment make-up water
were considered: (1) Municipal water suppliers; (2) offsite non-
drinking-water suppliers; and (3) on-site water. The only cost
associated with maintaining the moisture level within the pile is the
cost of the liquid. We assume that existing piping used to supply
lixiviant to the pile during leaching would be used to supply water
necessary for maintaining the moisture level. Also, we assume that the
facility will use the in-soil method for moisture monitoring. The in-
soil method and its costs are described below.
    Soil moisture sensors have been used for laboratory and outdoor
testing purposes and for agricultural applications for over 50 years.
They are mostly used to measure moisture in gardens and lawns to
determine when it is appropriate to turn on irrigation systems. Soil
moisture sensors can either be placed in the soil or held by hand.
    For example, one system would bury soil moisture sensors to the
desired depth in the heap. Then, a portable soil moisture meter would
be connected by cable to each buried sensor one at a time, i.e., a
single meter can read any number of sensors. The portable soil moisture
meter costs about $350, and each in-soil sensor about $35 or $45,
depending on the length of the cable (either 5 or 10 ft). Finally, it
is assumed that moisture readings would be performed during the NRC
required daily inspections of the heap leach pile, which would require
approximately 2,000 additional work hours per year per facility. Our
estimates for costs of monitoring the heap include 100 sensors located
within the heap, with a meter on each sensor. We chose 100 sampling
stations because heaps are generally the same size as conventional
impoundments, and Method 115 prescribed 100 measurements for the
tailings area of a conventional impoundment. The total estimated costs
for using this system, including labor, are approximately $86,500 per
year per facility.
    Alternatively, with a handheld soil moisture meter, two rods (up to
8 inches long) that are attached to the meter are driven into the soil
at the desired location, and a reading is taken. A handheld meter of
this type costs about $1,065, and replacement rods about $58 for a
pair. A minimum of 100 sampling stations for measuring radon could be
required. We did not estimate costs for this method, as we concluded