[Federal Register Volume 88, Number 93 (Monday, May 15, 2023)]
[Proposed Rules]
[Pages 30917-30934]
[FR Doc No: 2023-10068]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2017-0664; FRL-5925.1-01-OAR]
RIN 2060-AV58

National Emission Standards for Hazardous Air Pollutants:
Taconite Iron Ore Processing Amendments

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The U.S. Environmental Protection Agency (EPA) is proposing
amendments to the National Emission Standards for Hazardous Air
Pollutants (NESHAP) for Taconite Iron Ore Processing Plants, as
required by the Clean Air Act (CAA). To ensure that all emissions of
hazardous air pollutants (HAP) from sources in the source category are
regulated, the EPA is proposing emission standards for mercury. In
addition, the EPA is proposing to revise the existing emission
standards for hydrogen chloride and hydrogen fluoride.

DATES:
    Comments. Comments must be received on or before June 29, 2023.
Under the Paperwork Reduction Act (PRA), comments on the information
collection provisions are best assured of consideration if the Office
of

Management and Budget (OMB) receives a copy of your comments on or
before June 14, 2023.
    Public hearing: If anyone contacts us requesting a public hearing
on or before May 22, 2023, we will hold a virtual public hearing. See
SUPPLEMENTARY INFORMATION for information on requesting and registering
for a public hearing.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2017-0664, by any of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov/
(our preferred method). Follow the online instructions for submitting
comments.
     Email: [email protected]. Include Docket ID No. EPA-
HQ-OAR-2017-0664 in the subject line of the message.
     Mail: U.S. Environmental Protection Agency, EPA Docket
Center, Docket ID No. EPA-HQ-OAR-2017-0664, Mail Code 28221T, 1200
Pennsylvania Avenue NW, Washington, DC 20460.
     Hand/Courier Delivery: EPA Docket Center, WJC West
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004.
The Docket Center's hours of operation are 8:30 a.m.-4:30 p.m., Monday-
Friday (except Federal holidays).
    Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to https://www.regulations.gov/, including any personal information
provided. For detailed instructions on sending comments and additional
information on the rulemaking process, see the SUPPLEMENTARY
INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed
action, contact David Putney, Sector Policies and Programs Division
(D243-02), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711; telephone number:<PHONE_NUMBER>; email address:
[email protected].

SUPPLEMENTARY INFORMATION:
    Participation in virtual public hearing. To request a virtual
public hearing, contact the public hearing team at<PHONE_NUMBER> or by
email at [email protected]. If requested, the hearing will be
held via virtual platform on May 30, 2023. The hearing will convene at
10 a.m. Eastern Time (ET) and will conclude at 4 p.m. ET. The EPA may
close a session 15 minutes after the last pre-registered speaker has
testified if there are no additional speakers. The EPA will announce
further details at https://www.epa.gov/stationary-sources-air-pollution/taconite-iron-ore-processing-national-emission-standards-hazardous.
    If a public hearing is requested, the EPA will begin registering
speakers for the hearing no later than 1 business day after a request
has been received. To register to speak at the virtual hearing, please
use the online registration form available at https://www.epa.gov/stationary-sources-air-pollution/taconite-iron-ore-processing-national-emission-standards-hazardous or contact the public hearing team at
(888) 372-8699 or by email at [email protected]. The last day
to pre-register to speak at the hearing will be May 30, 2023. Prior to
the hearing, the EPA will post a general agenda that will list pre-
registered speakers in approximate order at: https://www.epa.gov/stationary-sources-air-pollution/taconite-iron-ore-processing-national-emission-standards-hazardous.
    The EPA will make every effort to follow the schedule as closely as
possible on the day of the hearing. However, please plan for the
hearings to run either ahead of schedule or behind schedule.
    Each commenter will have 4 minutes to provide oral testimony. The
EPA encourages commenters to provide the EPA with a copy of their oral
testimony electronically (via email) by emailing it to
[email protected]. The EPA also recommends submitting the text of
your oral testimony as written comments to the rulemaking docket.
    The EPA may ask clarifying questions during the oral presentations
but will not respond to the presentations at that time. Written
statements and supporting information submitted during the comment
period will be considered with the same weight as oral testimony and
supporting information presented at the public hearing.
    Please note that any updates made to any aspect of the hearing will
be posted online at https://www.epa.gov/stationary-sources-air-pollution/taconite-iron-ore-processing-national-emission-standards-hazardous. While the EPA expects the hearing to go forward as set forth
above, please monitor our website or contact the public hearing team at
(888) 372-8699 or by email at [email protected] to determine if
there are any updates. The EPA does not intend to publish a document in
the Federal Register announcing updates.
    If you require the services of a translator or special
accommodation such as audio description, please pre-register for the
hearing with the public hearing team and describe your needs by May 22,
2023. The EPA may not be able to arrange accommodations without
advanced notice.
    Docket. The EPA has established a docket for this rulemaking under
Docket ID No. EPA-HQ-OAR-2017-0664. All documents in the docket are
listed in https://www.regulations.gov/. Although listed, some
information is not publicly available, e.g., Confidential Business
Information (CBI) or other information whose disclosure is restricted
by statute. Certain other material, such as copyrighted material, is
not placed on the internet and will be publicly available only in hard
copy. With the exception of such material, publicly available docket
materials are available electronically in Regulations.gov.
    Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-
2017-0664. The EPA's policy is that all comments received will be
included in the public docket without change and may be made available
online at https://www.regulations.gov/, including any personal
information provided, unless the comment includes information claimed
to be CBI or other information whose disclosure is restricted by
statute. Do not submit electronically to https://www.regulations.gov/
any information that you consider to be CBI or other information whose
disclosure is restricted by statute. This type of information should be
submitted as discussed below.
    The EPA may publish any comment received to its public docket.
Multimedia submissions (audio, video, etc.) must be accompanied by a
written comment. The written comment is considered the official comment
and should include discussion of all points you wish to make. The EPA
will generally not consider comments or comment contents located
outside of the primary submission (i.e., on the Web, cloud, or other
file sharing system). For additional submission methods, the full EPA
public comment policy, information about CBI or multimedia submissions,
and general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    The https://www.regulations.gov/ website allows you to submit your
comment anonymously, which means the 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 the EPA without going through
https://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, the EPA recommends that you include your name and other
contact information in the body of your comment and with any digital
storage media you submit. If the EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, the
EPA may not be able to consider your comment. Electronic files should
not include special characters or any form of encryption and be free of
any defects or viruses. For additional information about the EPA's
public docket, visit the EPA Docket Center homepage at https://www.epa.gov/dockets.
    Submitting CBI. Do not submit information containing CBI to the EPA
through https://www.regulations.gov/. Clearly mark the part or all of
the information that you claim to be CBI. For CBI information on any
digital storage media that you mail to the EPA, note the docket ID,
mark the outside of the digital storage media as CBI, and identify
electronically within the digital storage media the specific
information that is claimed as CBI. In addition to one complete version
of the comments that includes information claimed as CBI, you must
submit a copy of the comments that does not contain the information
claimed as CBI directly to the public docket through the procedures
outlined in Instructions above. If you submit any digital storage media
that does not contain CBI, mark the outside of the digital storage
media clearly that it does not contain CBI and note the docket ID.
Information not marked as CBI will be included in the public docket and
the EPA's electronic public docket without prior notice. Information
marked as CBI will not be disclosed except in accordance with
procedures set forth in 40 Code of Federal Regulations (CFR) part 2.
    Our preferred method to receive CBI is for it to be transmitted
electronically using email attachments, File Transfer Protocol (FTP),
or other online file sharing services (e.g., Dropbox, OneDrive, Google
Drive). Electronic submissions must be transmitted directly to the
Office of Air Quality Planning and Standards (OAQPS) CBI Office at the
email address [email protected], and as described above, should include
clear CBI markings and note the docket ID. If assistance is needed with
submitting large electronic files that exceed the file size limit for
email attachments, and if you do not have your own file sharing
service, please email [email protected] to request a file transfer link.
If sending CBI information through the postal service, please send it
to the following address: OAQPS Document Control Officer (C404-02),
OAQPS, U.S. Environmental Protection Agency, Research Triangle Park,
North Carolina 27711, Attention Docket ID No. EPA-HQ-OAR-2017-0664. The
mailed CBI material should be double wrapped and clearly marked. Any
CBI markings should not show through the outer envelope.
    Preamble acronyms and abbreviations. Throughout this preamble the
use of ``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We
use multiple acronyms and terms in this preamble. While this list may
not be exhaustive, to ease the reading of this preamble and for
reference purposes, the EPA defines the following terms and acronyms
here:

1-BP 1-bromopropane
ACI activated carbon injection
BTF beyond-the-floor
CAA Clean Air Act
CBI Confidential Business Information
CFR Code of Federal Regulations
EPA Environmental Protection Agency
ERT Electronic Reporting Tool
ESP electrostatic precipitator
FR Federal Register
HAP hazardous air pollutant(s)
HCl hydrochloric acid
HF hydrogen fluoride
HI hazard index
HQ hazard quotient
km kilometer
lb/LT pounds of mercury emitted per long ton of pellets produced
MACT maximum achievable control technology
MIR maximum individual risk
NAICS North American Industry Classification System
NESHAP National Emission Standards for Hazardous Air Pollutants
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards
OMB Office of Management and Budget
PM particulate matter
PRA Paperwork Reduction Act
RDL representative detection level
REL reference exposure level
RFA Regulatory Flexibility Act
RTR residual risk and technology review
SBA Small Business Administration
SSM startup, shutdown, and malfunction
TOSHI target organ-specific hazard index
tpy tons per year
TRIM.FaTE Total Risk Integrated Methodology. Fate, Transport, and
Ecological Exposure model
UF uncertainty factor
UPL upper prediction limit
[mu]g/m3 microgram per cubic meter
UMRA Unfunded Mandates Reform Act
URE unit risk estimate
VCS voluntary consensus standards

    Organization of this document. The information in this preamble is
organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related
information?
II. Background
    A. What is the statutory authority for this action?
    B. What is this source category and how does the current NESHAP
regulate its HAP emissions?
    C. What data collection activities were conducted to support
this action?
    D. What other relevant background information and data are
available?
III. Analytical Procedures and Decision-Making
    A. How did we address unregulated pollutants?
    B. How did we perform the technology review?
IV. Analytical Results and Proposed Decisions
    A. What are the results of our analyses of unregulated
pollutants and how did we establish the proposed MACT standards?
    B. What are the results of our technology review and what
revisions to the MACT standards are we proposing?
    C. What performance testing are we proposing?
    D. What operating limits and monitoring requirements are we
proposing?
    E. What recordkeeping and reporting requirements are we
proposing?
    F. What are the results of any risk analyses completed for this
action?
    G. What other actions are we proposing?
    H. What compliance dates are we proposing?
V. Summary of Cost, Environmental, and Economic Impacts
    A. What are the affected sources?
    B. What are the air quality impacts?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What analysis of environmental justice did we conduct?
    F. What analysis of children's environmental health did we
conduct?
VI. Request for Comments
VII. Submitting Data Corrections
VIII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act (PRA)
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    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 Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
    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?

    Table 1 of this preamble lists the NESHAP and associated regulated
industrial source category that is the subject of this proposal. Table
1 is not intended to be exhaustive, but rather provides a guide for
readers regarding the entities that this proposed action is likely to
affect. The proposed standards, once promulgated, will be directly
applicable to the affected sources. Federal, State, local, and tribal
Government entities would not be affected by this proposed action. As
defined in the Initial List of Categories of Sources Under Section
112(c)(1) of the Clean Air Act Amendments of 1990 (see 57 FR 31576;
July 16, 1992) and Documentation for Developing the Initial Source
Category List, Final Report (see EPA-450/3-91-030; July 1992), the
Taconite Iron Ore Processing source category includes any facility
engaged in separating and concentrating iron ore from taconite, a low-
grade iron ore to produce taconite pellets. The source category
includes, but is not limited to, the following processes: liberation of
the iron ore by wet or dry crushing and grinding in gyratory crushers,
cone crushers, rod mills, and ball mills; pelletizing by wet tumbling
with a balling drum or balling disc; induration using a straight grate
or grate kiln indurating furnace; and finished pellet handling.

 Table 1--NESHAP and Source Categories Affected by This Proposed Action
------------------------------------------------------------------------
         Source category                  NESHAP          NAICS code \1\
------------------------------------------------------------------------
Taconite Iron Ore Processing.....  40 CFR part 63,                21221
                                    subpart RRRRR.
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\1\ North American Industry Classification System.

B. Where can I get a copy of this document and other related
information?

    In addition to being available in the docket, an electronic copy of
this action is available on the internet. Following signature by the
EPA Administrator, the EPA will post a copy of this proposed action at
https://www.epa.gov/stationary-sources-air-pollution/taconite-iron-ore-processing-national-emission-standards-hazardous. Following publication
in the Federal Register, the EPA will post the Federal Register version
of the proposal and key technical documents at this same website.
Information on the overall residual risk and technology review (RTR)
program is available at https://www3.epa.gov/ttn/atw/rrisk/rtrpg.html.
    A memorandum showing the rule edits that would be necessary to
incorporate the changes to 40 CFR part 63, subpart RRRRR proposed in
this action is available in the docket (Docket ID No. EPA-HQ-OAR-2017-
0664). Following signature by the EPA Administrator, the EPA also will
post a copy of this document to https://www.epa.gov/stationary-sources-air-pollution/taconite-iron-ore-processing-national-emission-standards-hazardous.

II. Background

A. What is the statutory authority for this action?

    This action proposes to amend the NESHAP for Taconite Iron Ore
Processing, which was previously amended when the EPA finalized the
Residual Risk and Technology Review for this source category on July
28, 2020.\1\
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    \1\ 85 FR 45476; July 28, 2020.
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    In the Louisiana Environmental Action Network v. EPA (LEAN)
decision issued on April 21, 2020, the U.S. Court of Appeals for the
District of Columbia Circuit (D.C. Circuit) held that the EPA has an
obligation to address unregulated emissions from a major source
category when the Agency conducts the 8-year technology review required
by CAA section 112(d)(6).\2\ This proposed rule addresses currently
unregulated emissions of HAP from the Taconite Iron Ore Processing
source category. Emissions data collected from the exhaust stacks of
existing taconite indurating furnaces indicate that mercury (Hg) is
emitted from the source category. However, mercury emissions from the
Taconite Iron Ore Processing source category are not regulated under
the existing Taconite Iron Ore Processing NESHAP. Therefore, the EPA is
proposing new standards that reflect MACT for mercury emitted from
taconite indurating furnaces, pursuant to CAA sections 112(d)(2) and
(3). We are also proposing to modify the existing emissions standards
for hydrochloric acid (HCl) and hydrofluoric acid (HF) pursuant to CAA
section 112(d)(6). CAA section 112(d)(6) separately requires the EPA to
review standards promulgated under CAA section 112 and revise them ``as
necessary (taking into account developments in practices, processes,
and control technologies)'' no less often than every 8 years. Based on
new information, we are proposing to revise the technology review
completed in 2020 by proposing revised HCl and HF standards at this
time.
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    \2\ Louisiana Environmental Action Network (LEAN) v. EPA, 955
F.3d 1088 (D.C. Cir. 2020).
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B. What is this source category and how does the current NESHAP
regulate its HAP emissions?

    The NESHAP for Taconite Iron Ore Processing (codified at 40 CFR
part 63, subpart RRRRR) regulates HAP emissions from new and existing
taconite iron ore processing plants that are major sources of HAP.
Taconite iron ore processing plants separate and concentrate iron ore
from taconite, a low-grade iron ore containing 20- to 25-percent iron,
and produce taconite pellets, which are 60- to 65-percent iron.
Taconite iron ore processing includes crushing and handling of the
crude ore, indurating, and finished pellet handling.
    The Taconite Iron Ore Processing NESHAP applies to each new or
existing ore crushing and handling operation, ore dryer, pellet
indurating furnace, and finished pellet handling operation at a
taconite iron ore processing plant that is (or is part of) a major
source of HAP emissions. There are currently eight taconite iron ore
processing plants in the United States: six facilities are located in
Minnesota and two are located in Michigan. While the Empire Mining
facility in Michigan maintains an air quality permit to operate, the
facility has been indefinitely idled since 2016. Therefore, the Empire
Mining facility is not included in any analyses (e.g., expected
emissions, estimated cost impacts, estimated emission reductions)
associated with this proposed rulemaking. A different taconite
facility, the Northshore Mining facility located in Minnesota, has been
temporarily idled since 2022, but is expected to resume operations as
early as Spring 2023. Therefore, we included the

Northshore Mining facility in the analyses conducted for this
rulemaking.
    Indurating furnaces represent the most significant source of HAP
emissions from the Taconite Iron Ore Processing source category. The
indurating furnaces are responsible for approximately 99 percent of
total HAP emissions from this source category. Indurating furnaces emit
acid gases, mercury and other metal HAP (e.g., arsenic, chromium,
nickel) that are present in the taconite ore and sometimes in the fuel
(such as coal) fed into the furnaces, and small amounts of organic HAP
(e.g., formaldehyde). The acid gases include HCl and HF and are formed
when chlorine and fluorine compounds are released from the raw
materials during the indurating process and combine with moisture in
the exhaust stream.
    The existing emission limits consist of particulate matter (PM)
limits, which serve as a surrogate for particulate metal HAP emissions;
PM also serves as a surrogate for HCl and HF. Table 2 lists the
emission standards that currently apply to taconite iron ore processing
facilities subject to 40 CFR part 63, subpart RRRRR. The current NESHAP
also includes work practice standards to address organic HAP emissions
and fugitive emissions.

     Table 2--Current PM Standards for Taconite Iron Ore Processing
------------------------------------------------------------------------
                                                            PM emission
          Affected source            Affected source is     limits (gr/
                                       new or existing       dscf) \1\
------------------------------------------------------------------------
Ore crushing and handling emission  Existing............           0.008
 units.
                                    New.................           0.005
Straight grate indurating furnace   Existing............            0.01
 processing magnetite.
                                    New.................           0.006
Grate kiln indurating furnace       Existing............            0.01
 processing magnetite.
                                    New.................           0.006
Grate kiln indurating furnace       Existing............            0.03
 processing hematite.
                                    New.................           0.018
Finished pellet handling emission   Existing............           0.008
 units.
                                    New.................           0.005
Ore dryer.........................  Existing............           0.052
                                    New.................           0.025
------------------------------------------------------------------------
\1\ gr/dscf = grains per dry standard cubic foot.

    The taconite iron ore processing NESHAP also regulates fugitive
emissions from stockpiles (including uncrushed and crushed ore and
finished pellets), material transfer points, plant roadways, tailings
basins, pellet loading areas, and yard areas. Fugitive emissions must
be controlled using the work practices specified in a facility's
fugitive dust emissions control plan.
    The EPA previously conducted a residual risk and a technology
review pursuant to CAA sections 112(f)(2) and 112(d)(6), respectively
(Docket Item No. EPA-HQ-OAR-2017-0664-0164). The EPA published the RTR
proposed rule on September 25, 2019 (84 FR 50660), and the RTR final
rule on July 28, 2020 (85 FR 45476). In the final rule, the EPA
concluded that the risks associated with HAP emissions from taconite
iron ore processing were acceptable and that the current NESHAP
provides an ample margin of safety to protect public health. In the
2020 final rule, the EPA concluded that there were no developments in
practices, processes, or control technologies that would warrant
revisions to the standards. Therefore, no changes were made to the
emissions standards as part of that action. However, the 2020
rulemaking removed the exemptions for periods of startup, shutdown, and
malfunction (SSM), included provisions requiring electronic reporting,
and made some other minor changes to the NESHAP.

C. What data collection activities were conducted to support this
action?

    Prior to developing the initial MACT standards for the Taconite
Iron Ore Processing source category, which were finalized in 2003 (68
FR 61868; October 30, 2003), the EPA collected information on the
emissions, operations, and location of taconite iron ore processing
facilities. To inform the development of the 2019 RTR proposed rule, we
obtained data from the EPA's 2014 National Emissions Inventory (NEI)
database (https://www.epa.gov/air-emissions-inventories/2014-national-emissions-inventory-nei-data) and supplemental information submitted by
industry. Data on the numbers, types, dimensions, and locations of the
emission points for each facility were obtained from the NEI, state
agencies, Google EarthTM, and taconite iron ore processing
industry staff. To inform this current action, in 2022, pursuant to CAA
section 114, the EPA sent an information request (hereinafter ``2022
CAA section 114 information request'') to seven facilities in the
source category to obtain updated information about taconite iron ore
processing facilities. (The EPA did not send an information request to
the Empire Mining facility since, as discussed in section II.B of this
preamble, above, that facility has been indefinitely idled since 2016.)
The 2022 CAA section 114 information request consisted of a
questionnaire and stack testing requirements. The questionnaire was
used to collect information on the location and number of indurating
furnaces, production throughput, types of pellets produced, types and
quantities of fuels burned, information on air pollution control
devices and emission points, historical test data, and other
documentation (e.g., title V permits). Two companies (U.S. Steel
Corporation and Cleveland-Cliffs Incorporated) completed the
questionnaire for which they reported data for seven major source
facilities.\3\
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    \3\ As discussed in section II.B, this does not include the
Empire Mining facility, which has been indefinitely idled since
2016.
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    In addition to the questionnaire, the EPA required each taconite
iron ore processing facility, with the exception of the Empire Mining
facility, to complete stack testing of one or more representative
indurating furnaces for the following pollutants: filterable PM, metal
HAP, and the acid gases HCl and HF.\4\ EPA Method 5 was used to measure
filterable PM, EPA Method 29 was used to measure metal HAP emissions,
and EPA Method 26A was

used to measure HCl and HF emissions. Six facilities completed the
required stack testing and submitted emissions data for a total of
seven indurating furnaces.\5\
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    \4\ The EPA did not require the Empire Mining facility to submit
stack testing because the facility has been indefinitely idled since
2016.
    \5\ The EPA initially planned to require the Northshore Mining
facility to conduct stack testing. However, the facility's
indurating furnaces were idled during the period of the information
collection and are not expected to return to operation until at
least spring 2023. As a result, we ultimately did not require the
Northshore Mining facility to complete stack testing within the
timeframe available before the Administrator's signature of this
proposed rule.
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    In this action, the EPA used the emissions data collected from the
2022 CAA section 114 information request, as well as results from
previous stack tests completed from 2014 through 2021 to develop
proposed MACT standards for mercury, pursuant to CAA sections 112(d)(2)
and (3).\6\ We also used the emissions data for HCl and HF collected
from the 2022 CAA section 114 information request to inform proposed
revisions to the existing emissions standards for these acid gases,
pursuant to CAA section 112(d)(6). The data collected and considered
are available in the docket for this action. In addition, the data
collection and analyses for this action are described in detail in two
documents, Maximum Achievable Control Technology (MACT) Analysis for
Proposed Mercury Standards for Taconite Iron Ore Indurating Furnaces
and Revised Technology Review of Acid Gas Controls for Indurating
Furnaces in the Taconite Iron Ore Processing Source Category, both of
which are available in the docket for this action (Docket ID No. EPA-
HQ-OAR-2017-0664).
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    \6\ Due to the relative scarcity of stack test data available
from the taconite iron ore processing facilities, additional mercury
emissions data from testing performed from 2014 through 2021 at
facilities listed in the 2022 CAA section 114 information request
were also used in development of the MACT standards for mercury.
This testing was performed under similar conditions and testing
methodologies that were requested in the 2022 CAA section 114
information request.
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D. What other relevant background information and data are available?

    In addition to the 2022 CAA section 114 information request
discussed in section II.C. of this preamble, the EPA also reviewed the
information sources listed below to help inform the development of the
proposed MACT standards for mercury and to determine whether there have
been developments in practices, processes, or control technologies for
taconite iron ore processing facilities pursuant to CAA section
112(d)(6). These additional information sources include the following:
     Emissions tests and reports for testing completed between
2014 and 2021 on 11 indurating furnaces located at six plants in
Minnesota. Stack tests on nine furnaces used EPA Method 29 to measure
mercury emissions, stack tests on three furnaces used the Ontario Hydro
method (ASTM D6784-16), and stack tests on one furnace used EPA Method
29 and the Ontario Hydro method.
     Data on the variation of the concentration of mercury in
the ore from the mines used by taconite iron ore processing facilities
provided by industry and the American Iron and Steel Institute (the
industry association representing the industry in the affected NAICS
category and their members).
     Site-specific Mercury Reduction Plans and mercury control
technology evaluations required by Minnesota state regulations.\7\
These documents include Mercury Reduction Plans for Northshore Mining
Company in Silver Bay, Minnesota and Minorca Mine, Inc. in Virginia,
Minnesota; and technology evaluations for the following four plants:
Hibbing Taconite Company in Hibbing Minnesota; United Taconite LLC in
Forbes Minnesota, U.S. Steel--Minntac in Mountain Iron, Minnesota and
U.S. Steel--Keetac in Keewatin, Minnesota.
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    \7\ The Mercury Reduction Plans and mercury control technology
evaluations were submitted to the Minnesota Pollution Control Agency
(MPCA) in 2018 in response to a Minnesota regulation (see Minn. R.
7007.0502) requiring mercury emission reductions of 72 percent from
2008 or 2010 emission levels by January 1, 2025. The regulation
requires a mercury reduction plan for sources that emit more than 3
pounds of mercury (or 5 pounds for industrial boilers). We also
considered the MPCA responses to the industry submittals.
---------------------------------------------------------------------------

    Copies of these materials are available in the docket for this
action (Docket ID No. EPA-HQ-OAR-2017-0664).

III. Analytical Procedures and Decision-Making

    In this section, we describe the analyses performed to support the
proposed decisions for the issues addressed in this proposal.

A. How did we address unregulated pollutants?

    In evaluating the Taconite Iron Ore Processing source category and
emissions data collected in support of the 2020 RTR and through the
2022 CAA section 114 information request, we identified mercury as a
HAP emitted from facilities in the source category. Mercury, which is
emitted primarily in a gaseous form (not as a particle), is not
regulated under the existing standards for the source category.
Emissions data from stack tests conducted since 2014 indicate mercury
is emitted by indurating furnaces at taconite iron ore processing
facilities. Mercury was the only HAP identified by the EPA that is not
regulated under the existing standards for this source category. The
EPA has a ``clear statutory obligation to set emissions standards for
each listed HAP'' emitted from a source category.\8\ In this action, we
are proposing emissions limits for mercury pursuant to CAA sections
112(d)(2) and (3) for new and existing indurating furnaces.
---------------------------------------------------------------------------

    \8\ National Lime v. EPA, 233 F. 3d 625, 634 (D.C. Cir. 2000).
---------------------------------------------------------------------------

    Pursuant to CAA section 112(d)(3), since there are fewer than 30
sources in the category, the minimum standards for existing sources are
calculated based on the average performance of the best-performing five
sources in the source category, taking into consideration the
variability of HAP emissions from the emission sources. This is
commonly referred to as the ``MACT floor.'' The MACT floor for new
sources is based on the single best-performing source, with a similar
consideration of variability in emissions from the best-performing
source. The MACT floor for new sources cannot be less stringent than
the emissions performance that is achieved in practice by the best-
controlled similar source. To account for variability in the mercury
emissions from indurating furnaces, we calculated the MACT floors using
the 99-percent Upper Prediction Limit (UPL) approach from the stack
test data collected for the 2022 CAA section 114 information request
and data from the stack tests completed on indurating furnaces from
2014 through 2021.
    The UPL approach addresses variability of emissions data from the
best-performing source or sources in setting MACT standards. The UPL
also accounts for uncertainty associated with emission values in a
dataset, which can be influenced by components such as the number of
samples available for developing MACT standards and the number of
samples that will be collected to assess compliance with the emission
limit. The UPL approach has been used in many environmental science
applications. As explained in more detail in the memorandum Use of
Upper Prediction Limit for Calculating MACT Floors which is available
in the docket for this action (Docket ID No. EPA-HQ-OAR-2017-0664), the
EPA uses the UPL approach to reasonably estimate the emissions
performance of the best-performing source or sources to establish MACT
floor standards.
    In addition to calculating the MACT floor, the EPA must examine
more stringent ``beyond-the-floor'' (BTF) regulatory options to
determine MACT.

Unlike the MACT floor's minimum stringency requirements, the EPA must
consider various impacts of the more stringent regulatory options in
determining whether the proposed MACT standards should reflect beyond-
the-floor requirements. If the EPA concludes that the more stringent
regulatory options have unreasonable cost, non-air quality health and
environmental, and/or energy impacts, the EPA selects the MACT floor as
MACT. However, if the EPA concludes that impacts associated with BTF
levels of control are reasonable in light of additional emissions
reductions achieved, the EPA selects those BTF levels of control as
MACT.
    The methodology used to develop the new mercury standards is
described in detail in the document, Maximum Achievable Control
Technology (MACT) Analysis for Proposed Mercury Standards for Taconite
Iron Ore Indurating Furnaces, located in the docket for this action
(Docket ID No. EPA-HQ-OAR-2017-0664). The results and proposed
decisions based on the analyses performed pursuant to CAA sections
112(d)(2) and (3) are presented in section IV.A of this preamble.

B. How did we perform the technology review?

    Emissions data collected as part of the 2022 CAA section 114
information request indicated that indurating furnaces using wet
scrubbers to meet the NESHAP emissions standards have significantly
lower acid gas emissions than those using other types of PM control.
These emissions data were not available to us at the time of the 2020
technology review. Based on the new data, we determined it was
appropriate to revisit the existing standards for HCl and HF in light
of the air pollution control technologies available to control HCl and
HF emissions from indurating furnaces.
    When we conduct technology reviews, we primarily focus on the
identification and evaluation of developments in practices, processes,
and control technologies that have occurred since the MACT standards
were promulgated. Where we identify such developments, we analyze their
technical feasibility, estimated costs, energy implications, and non-
air environmental impacts. We also consider the emission reductions
associated with applying each development. This analysis informs our
decision of whether it is ``necessary'' to revise the emissions
standards. In addition, we consider the appropriateness of applying
controls to new sources versus retrofitting existing sources. For this
exercise, we consider any of the following to be a ``development'':
     Any add-on control technology or other equipment that was
not identified and considered during development of the original MACT
standards;
     Any improvements in add-on control technology or other
equipment (that were identified and considered during development of
the original MACT standards) that could result in additional emissions
reduction;
     Any work practice or operational procedure that was not
identified or considered during development of the original MACT
standards;
     Any process change or pollution prevention alternative
that could be broadly applied to the industry and that was not
identified or considered during development of the original MACT
standards; and
     Any significant changes in the cost (including cost
effectiveness) of applying controls (including controls the EPA
considered during the development of the original MACT standards).
    In addition to reviewing the practices, processes, and control
technologies that were considered at the time we originally developed
(or last updated) the NESHAP, we review a variety of data sources in
our investigation of potential practices, processes, or controls. See
sections II.C and II.D of this preamble for information on the specific
data sources that were reviewed as part of the technology review.

IV. Analytical Results and Proposed Decisions

A. What are the results of our analyses of unregulated pollutants and
how did we establish the proposed MACT standards?

    In this action, we are proposing mercury MACT standards for new and
existing indurating furnaces, pursuant to CAA sections 112(d)(2) and
(3). The results and proposed decisions based on the analyses performed
pursuant to CAA sections 112(d)(2) and (3) are presented below.
    Before calculating the MACT floor, we evaluated the available data
on the design and operating characteristics of indurating furnaces to
determine whether subcategorization was warranted. For each stack test,
we collected information on the type of indurating furnace tested
(grate kiln or straight grate indurating furnace), fuels burned, ore
processed (magnetite or hematite), and the type and quantity of
taconite pellets produced.
    Regarding furnace type, there are eight straight grate indurating
furnaces and 13 grate kiln indurating furnaces located at taconite iron
ore processing facilities in the United States. This includes three
grate kiln indurating furnaces at the Empire Mining facility. However,
as discussed in section II.B, above, the Empire Mining facility has
been indefinitely idled since 2016 and its three grate kiln indurating
furnaces are not included in any analyses associated with this proposed
action. Grate kiln furnaces consist of a moving grate and rotary kiln.
Unfired (green) pellets are placed directly on a travelling grate which
transports the pellets through a dryer and pre-heater to the rotary
kiln, where induration occurs. Straight grate furnaces consist of a
continuously moving grate that carries the green pellets through the
furnace's different temperature zones. Unlike the grate kiln furnace
where the green pellets are placed directly on the grate, the green
pellets in a straight grate furnace are placed on a 4- to 6-inch layer
of previously fired pellets known as the hearth layer. The hearth layer
allows for even air flow and protects the grate from the heat generated
by the oxidation of the taconite pellets during induration. We compared
the mercury emissions data for straight grate furnaces with the
emissions data for grate kiln furnaces to determine whether there was a
difference in emissions attributable to differences in furnace design.
We currently have mercury emissions data from stack testing completed
on five straight grate furnaces and nine grate kiln furnaces. We
compared the average emissions in pounds of mercury per long ton of
pellets produced (lb/LT) from grate kiln furnaces with that of straight
grate furnaces and found the average was slightly higher for grate kiln
furnaces (1.98 x 10-\5\ lb/LT for grate kiln furnaces versus
1.80 x 10-\5\ lb/LT for straight grate furnaces). We next
ranked the 14 furnaces from lowest- to highest-emitter and found that
one straight grate furnace had an emission rate lower than any of the
grate kiln furnaces, while the other four straight grate furnaces had
emissions rates comparable to those of grate kiln furnaces. We propose
to conclude based on this information that subcategorizing based on
furnace types is not warranted.
    We also evaluated whether subcategorizing based on the type of ore
processed would be appropriate. In the United States, there are two
types of iron ore processed at taconite iron ore processing facilities:
magnetite and hematite. Only one of the seven taconite plants processes
hematite ore (Tilden Mining located in Michigan). This plant

operates two grate kiln furnaces. We currently have mercury emissions
data for only one of the two grate kiln furnaces located at this plant.
The mercury emission rate for this grate kiln furnace was lower than
all but one of the furnaces processing magnetite ore. Since we have
emissions data for only one of the two grate kiln furnaces currently
processing hematite, we propose to conclude the data set is too limited
to justify subcategorizing by ore type.
    Next, we evaluated whether subcategorizing by fuel type would be
appropriate. Most indurating furnaces can burn natural gas, coal, fuel
oil, wood, and/or a fuel mixture (e.g., coal and natural gas). However,
responses to the 2022 CAA section 114 information request indicated
that natural gas is the most common fuel used in indurating furnaces,
with natural gas reported as the primary fuel for 14 furnaces. A
natural gas and wood mix was used as the primary fuel for three
furnaces, while natural gas and coal or coke blend was reported as the
primary fuel for one furnace. Most of the furnaces were burning natural
gas during the testing conducted pursuant to the 2022 CAA section 114
information request and most stack test data available to us are for
furnaces burning natural gas. As part of the 2022 CAA section 114
information request, one facility completed two stack tests--one when
burning only natural gas and one when co-firing with natural gas and
coal. The stack tests were completed on the same furnace and the
results showed a slight increase in mercury emissions from 2.08 x
10-\5\ lb/LT when burning only natural gas to 2.29 x
10-\5\ lb/LT when burning a mixture of natural gas and coal.
We would expect higher mercury emissions from furnaces burning coal
because coal is known to contain mercury and to emit mercury when
burned. We would also expect mercury emissions from coal to vary based
on the quantity of coal burned and the mercury content of the coal
burned. However, based on the 2022 stack testing described above, the
contribution of mercury from coal combustion to the overall mercury
emissions appears to be relatively small. The 2022 stack test data
suggests that most of the mercury emissions arise from mercury released
from the taconite ore during induration. We expect that this result is
likely due primarily to the relatively small mass of coal consumed
compared to the mass of green pellets processed. For the furnace tested
in 2022 while co-firing natural gas and coal, the mass of green pellets
processed per hour was over 110 times greater than the mass of coal
burned per hour. Based on this information, we do not believe that
variations in mercury emissions are attributable to fuel-type and
propose to conclude that subcategorizing based on fuel-type is not
warranted.
    Finally, we evaluated whether subcategorizing based on the type of
taconite pellets produced would be appropriate. Taconite iron ore
processing plants produce two types of pellets: standard (also known as
acid) pellets and fluxed pellets. Standard pellets are produced by
mixing the concentrated ore with a binding agent (typically bentonite).
Fluxed pellets are produced by adding a fluxing agent (typically
limestone and/or dolomite) in addition to the binding agent. Based on
the information reported in responses to the 2022 CAA section 114
information request, 15 of the 18 indurating furnaces produce both
standard and fluxed pellets, whereas three furnaces located at two
plants produce exclusively fluxed pellets. A comparison of the mercury
emissions data indicated no significant difference in mercury emissions
based on pellet type produced. The maximum measured mercury emissions
were 2.54 x 10-5 lb/LT while producing flux pellets and 2.51
x 10-5 lb/LT while producing standard pellets. Based on this
information, we propose to conclude that subcategorization based on
pellet type is not appropriate.
    Overall, based on our evaluation of the data, as discussed above,
we are proposing that subcategorization is not appropriate for these
emission sources (i.e., the indurating furnaces) when considering
mercury emissions.
    To determine the proposed MACT standards for mercury for existing
indurating furnaces in the source category, we evaluated two potential
options as follows: (1) setting standards at the MACT floor for new and
existing indurating furnaces; and (2) setting beyond-the-floor MACT
standards which are more stringent than the MACT floors for new and
existing indurating furnaces.
    Under Option 1, mercury limits for new and existing indurating
furnaces would be set at the MACT floor level, based on the 99-percent
UPL, and would apply individually to each furnace at each facility. We
calculated the mercury MACT floor limits in units of pounds of mercury
per long ton of taconite pellets produced (lb/LT) for existing sources
based on the five best performing furnaces and for new sources based on
the best performing furnace. The result was a MACT floor limit of 1.4 x
10-\5\ lb/LT for existing sources and a MACT floor limit of
3.1 x 10-\6\ lb/LT for new sources.
    We compared the mercury emission rates for each existing indurating
furnace to the MACT floor limit (i.e., 1.4 x 10-\5\ lb/LT)
to estimate the number of existing indurating furnaces that would
require improved performance to meet the MACT floor limits. The
emissions rates for the 14 indurating furnaces for which we have test
data were based on the average mercury emissions rates measured during
stack testing for each of those furnaces. For the remaining four
indurating furnaces for which stack test data are not available,\9\ we
used the mercury emissions rates determined through stack testing on
indurating furnaces of the same size and design located at the same
plant. Based on this analysis, we estimate that 11 existing indurating
furnaces would require improved performance to comply with the mercury
MACT floor limit and seven furnaces would not require improved
performance. We determined that activated carbon injection (ACI) with a
high efficiency venturi scrubber would provide the level of mercury
reduction required for the 11 existing furnaces to achieve compliance
with the proposed MACT floor.
---------------------------------------------------------------------------

    \9\ These include one indurating furnace at the Tilden facility
and three indurating furnaces at the Northshore facility.
---------------------------------------------------------------------------

    Using ACI with a high efficiency venturi scrubber on the 11
furnaces we expect would require additional controls would result in a
combined estimated reduction of 462 pounds of mercury per year from
these sources. We estimate that the total capital investment to
retrofit 11 existing furnaces with these controls would be $129 million
and the total annual costs would be $71 million per year.
    We are proposing to set mercury standards at the MACT floor for new
and existing sources, as described above. We request comment on this
proposed approach.
    Under Option 2, we evaluated setting beyond-the-floor MACT
standards that are more stringent than the MACT floor standards
discussed in Option 1. We considered limits at levels of 10 percent
more stringent than the MACT floor, 20 percent more stringent than the
MACT floor, 30 percent more stringent than the MACT floor, and 40
percent more stringent than the MACT floor. We considered increased
stringency at 10 percent intervals up to 40 percent based on
engineering judgement that such intervals were appropriate due to the
expected margins of error associated with estimated control
efficiencies and required carbon injection rates. Using

smaller intervals would have resulted in overlap of the margins of
error between intervals and using larger intervals would have resulted
in less precision of results. Therefore, we decided to use 10 percent
intervals. Nevertheless, we solicit comments and information regarding
this approach.
    We estimate that ACI with high efficiency venturi scrubbers could
achieve standards up to 30 percent more stringent than the MACT floor,
but at increased rates of carbon injection as the standards increase in
stringency from 10 percent more stringent than the MACT floor up to 30
percent more stringent than the MACT floor. Based on our analysis, we
expect that for standards that are at least 40 percent more stringent
than the MACT floor, a baghouse would be required after the wet
scrubber for one facility (Keetac). Of the beyond-the-floor options
considered, we estimate that the most cost-effective beyond-the-floor
option would be to set the MACT standard for existing furnaces at a
level 30 percent more stringent than the MACT floor (i.e., a MACT
standard of 8.4 x 10-\6\ lb/LT). Under this scenario, we
estimate that 11 of the 18 existing indurating furnaces would require
additional controls to meet the beyond-the-floor limit, and that these
11 furnaces could meet the beyond-the-floor limit using ACI (at a
higher rate than needed to meet the 10 percent and 20 percent levels)
with a high efficiency venturi scrubber. Under this approach, we
estimate a total reduction of 621 pounds of mercury per year from the
source category at an estimated incremental cost-effectiveness of about
$46,000 per pound of mercury removed to go beyond the MACT floor. This
is above the $/pound of mercury reduced that we have historically found
to be reasonable and cost-effective when considering beyond-the-floor
options for regulating mercury emissions. Further, our analysis
indicates that some new furnaces (e.g., if a new furnace was installed
at the Keetac facility) would require ACI plus baghouses to comply with
the MACT floor standard and that any increase in stringency of the
standard (i.e., any beyond-the-floor standard) for new sources, would
also result in cost-effectiveness, measured in $/pound of mercury
removed, that is higher on a $/pound basis than cost-effective numbers
that the EPA has historically considered reasonable when considering
beyond-the-floor options for regulating mercury emissions. We propose
to conclude that requiring new or existing indurating furnaces to meet
beyond-the-floor limits is not reasonable based on the estimated
capital and operating costs and cost-effectiveness.
    A detailed description of the analyses of mercury emissions,
including consideration of subcategorization, the calculation of the
MACT floor limits for new and existing furnaces, and the analysis of
beyond-the-floor options (including the estimated costs, reductions and
cost effectiveness of each option), are included in the memorandum,
Maximum Achievable Control Technology (MACT) Analysis for Proposed
Mercury Standards for Taconite Iron Ore Indurating Furnaces. A
description of the APCDs that we expect would be necessary to reduce
emissions and the estimated costs of those controls are included in the
memorandum Development of Impacts for the Proposed Amendments to the
NESHAP for Taconite Iron Ore Processing. Copies of these memoranda are
available in the docket for this action (Docket ID No. EPA-HQ-OAR-2017-
0664).
1. What alternative compliance provisions are being proposed?
    As discussed in section IV.A, we are proposing to set mercury
emission standards at the MACT floor level for new and existing sources
that would apply to indurating furnaces on a unit-by-unit basis. We are
also proposing an emissions averaging compliance alternative that would
allow owners and operators of taconite iron ore processing facilities
to demonstrate compliance by averaging mercury emissions across
existing indurating furnaces located at the same taconite facility.
Under this emissions averaging compliance alternative, a taconite iron
ore processing facility with more than one indurating furnace may
average mercury emissions across the indurating furnaces located at the
facility provided that the mercury emissions averaged across all
indurating furnaces at the facility do not exceed a mercury emission
limit of 1.26 x 10-\5\ lb/LT, on a production-weighted
basis. This emission limit reflects a 10 percent adjustment factor to
the MACT floor standard; according to our analysis, we expect this
emission limit would result in mercury reductions greater than those
achieved by application of the MACT floor on a unit-by-unit basis.
    We are proposing this emissions averaging compliance alternative
for existing indurating furnaces because we expect it will result in a
greater level of mercury reduction than the unit-by-unit MACT floor
limit at a lower cost per pound of mercury removed, while also
providing compliance flexibility. The proposed emissions averaging
compliance alternative is available only to existing indurating
furnaces at taconite iron ore processing facilities. New or
reconstructed indurating furnaces would be subject to the unit-by-unit
MACT floor standards as discussed in section IV.A above, and would be
required to comply with those standards on a unit-by-unit basis.
Specifically, we are proposing that indurating furnaces constructed or
reconstructed after May 15, 2023 would be considered new sources and
would be required to comply with the proposed MACT floor emission
standard for new sources of 3.1 x 10-\6\ lb/LT.
    We expect that the United Taconite, Hibbing, and Minntac taconite
iron ore processing facilities may elect to utilize this emissions
averaging compliance alternative. If these three taconite iron ore
processing facilities utilize the emissions averaging compliance
alternative, then we expect that six of the 18 indurating furnaces in
the source category \10\ would require the addition of ACI with a
venturi scrubber. We estimate that this emissions averaging compliance
alternative would result in total emissions reductions of 497 pounds of
mercury per year, assuming that these three taconite iron ore
processing facilities elect to use the emissions averaging compliance
alternative to demonstrate compliance with the standards. We estimate
that, under this emissions averaging compliance alternative, the total
capital investment for industry would be $90 million and total annual
costs would be $52 million.
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    \10\ As discussed in section II.B, this excludes the three grate
kiln indurating furnaces at the Empire Mining facility.
---------------------------------------------------------------------------

    We recognize that the EPA has generally imposed limits on the scope
and nature of emissions averaging programs. These limits include: (1)
no averaging between different types of pollutants; (2) no averaging
between sources that are not part of the same affected facility; (3) no
averaging between individual sources within a single major source if
the individual sources are not subject to the same NESHAP; and (4) no
averaging between existing sources and new sources. The emissions
averaging allowed under the proposed emissions averaging compliance
option in this action fully satisfies each of these criteria. First,
emissions averaging would only be allowed for mercury emissions.
Second, emissions averaging would only be permissible among individual
existing affected units at a single stationary source (i.e., the
facility). Third,

emissions averaging would only be permitted among indurating furnaces
at the facility. Lastly, new affected sources could not use emissions
averaging for compliance purposes. Accordingly, we have concluded that
the averaging of emissions across affected units at a single taconite
facility is consistent with the CAA.
    We are also proposing to require that each facility that intends to
utilize the emissions averaging compliance alternative develop an
emissions averaging plan, which would provide additional assurance that
the necessary criteria will be followed. We are proposing to require
that a facility's emissions averaging plan include the identification
of: (1) all units in the averaging group; (2) the control technology
installed; (3) the process parameter(s) that will be monitored; (4) the
specific control technology or pollution prevention measure to be used;
(5) the test plan for the measurement of the HAP being averaged; and
(6) the operating parameters to be monitored for each control device. A
state, local, or tribal regulatory agency that is delegated authority
for this rulemaking could require the emissions averaging plan to be
submitted or even approved before emissions averaging could be used.
Upon receipt, the regulatory authority would not be able to approve an
emissions averaging plan differing from the eligibility criteria
contained in the proposed rule.
    We are proposing an emissions averaging compliance alternative
because we expect it will provide a more flexible and less costly
alternative to controlling mercury emissions from the source category,
and we expect it will result in greater annual reductions of mercury
emissions from the source category than unit-by-unit compliance. We
expect that the proposed emissions averaging compliance alternative as
described above would not lessen the stringency of the overall MACT
floor level of performance and would provide flexibility in compliance,
cost, and energy savings to owners and operators. We also recognize
that we must ensure that any emissions averaging option can be
implemented and enforced, will be clear to sources, and most
importantly, will be no less stringent than unit-by-unit implementation
of the MACT floor limits.
    Under the proposed emissions averaging compliance alternative, we
expect the 10 percent adjustment factor will ensure that the total
quantity of mercury emitted from a facility's indurating furnaces will
not be greater than if the facility's furnaces individually complied
with the unit-by-unit MACT floor standards. We expect that the
practical outcome of emissions averaging will be mercury emissions
reductions equivalent to, or greater than, mercury reductions achieved
through compliance with the MACT floor limits for each discrete
indurating furnace on a unit-by-unit basis, and that the statutory
requirement that the MACT standard reflect the maximum achievable
emissions reductions would therefore be fully effectuated under this
approach. We request comment on allowing sources to comply with the
mercury MACT standards through the proposed emissions averaging
compliance alternative. We also request comment on the appropriate
adjustment factor to apply under this proposed compliance alternative.
2. What information did the EPA receive regarding mercury variation in
taconite iron ore?
    On February 14, 2023, the EPA received data from the American Iron
and Steel Institute (AISI) and U.S. Steel Corporation (U.S. Steel) on
the variation of mercury concentration within the taconite ore used by
taconite iron ore processing facilities. U.S. Steel and AISI requested
that these data be considered as one of the variability factors while
developing the MACT standards for mercury emitted from indurating
furnaces. AISI also suggested corrections to the mercury stack test
emissions data that we used to develop the proposed MACT standards for
mercury on March 13, 2023. On April 27, 2023, AISI and U.S. Steel also
submitted suggestions on how to account for variations in mercury,
chloride, and fluoride concentrations in taconite ore when developing
standards for emissions of mercury, hydrogen chloride, and hydrogen
fluoride from indurating furnaces. We did not have sufficient time
prior to issuing this proposal to fully assess the information
submitted but have made the submittals available in the docket for this
action (Docket ID No. EPA-HQ-OAR-2017-0664). Therefore, the MACT
standards for mercury proposed in this action do not include
consideration of this information submitted by AISI and U.S. Steel. We
request comment on the submittals in general and on the data on the
variation of mercury content in taconite ore and whether and to what
extent this variation should be considered in the development of the
MACT standards for mercury from indurating furnaces (see discussion in
section IV.A. of this preamble).

B. What are the results of our technology review and what revisions to
the MACT standards are we proposing?

    The existing NESHAP for the taconite iron ore processing source
category includes standards for HCl and HF that utilize PM as a
surrogate for HCl and HF. As discussed below, however, we are proposing
to change the way we regulate HCl and HF emissions from the source
category based on a development in the industry. Specifically, we are
proposing numerical emission limits for HCl and HF instead of relying
on PM as a surrogate for emissions of these specific HAP.
    This proposal is consistent with the EPA's authority pursuant to
CAA section 112(d)(6) to take developments in practices, processes, and
control technologies into account to determine if it is ``necessary''
to revise the MACT standards previously set by the EPA. In this
proposal, we are using our discretion to revisit part of the 2020
technology review; our review is limited to developments pertaining to
the regulation of HCl and HF. The reasons for this proposal are
discussed below.
    As described in section III.B of this preamble, the technology
review for the 2020 Taconite Iron Ore Processing RTR rulemaking focused
on identifying and evaluating potential developments in practices,
processes, and control technologies that have occurred since the NESHAP
was promulgated in 2003.\11\ Based on the information available to us
at the time the 2020 RTR was promulgated, we concluded there were no
developments in practices, processes, and control technologies for
indurating furnaces. However, as part of the 2022 CAA section 114
information request, we collected new data on HCl and HF emissions from
seven indurating furnaces. Six of the furnaces tested were equipped
with wet venturi scrubbers and one furnace was equipped with dry
electrostatic precipitators (ESPs). The HCl and HF emissions data
showed that wet venturi scrubbers consistently achieved lower HCl
emissions compared to the furnaces using dry ESPs. The results for HF
are less clear, but we still expect wet controls achieve better control
of HF compared to dry controls because HF is quite soluble in water.
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    \11\ For information on the technology review completed in 2020,
see the memorandum ``Final Technology Review for the Taconite Iron
Ore Processing Source Category,'' January 3, 2020 (available in the
docket for this action; Docket Item ID No. EPA-HQ-OAR-2017-0664-
0164).
---------------------------------------------------------------------------

    Based on our review of this new emission data and understanding of
the chemistry of these compounds, the EPA

is proposing amendments to the existing NESHAP, pursuant to CAA section
112(d)(6). The current NESHAP includes PM limits used as a surrogate
for acid gas emissions. In this action, we are proposing that furnaces
would be required to comply with the proposed numerical emission limits
for HCl and HF, which would replace the use of PM emissions as a
surrogate for emissions of HCl and HF from the source category.
    The proposed revised HCl and HF emission limits for new and
existing indurating furnaces were determined using a methodology
similar to, but slightly different than, that used to develop the
mercury emission limits. The mercury MACT floor limits were derived by
calculating the UPL based on emissions test data for the top five
performing (lowest emitting) sources pursuant to CAA section 112(d)(2)/
(3). Since we are proposing a different approach to regulating HCl and
HF limits from the approach in the current regulations, under the
limited CAA section 112(d)(6) technology review, the objective was to
calculate a proposed limit that reflects the performance (i.e., level
of emissions) of the taconite indurating furnaces that have wet venturi
scrubbers (i.e., the superior control technology for control of acid
gases, especially HCl). Therefore, for existing furnaces, we used the
emissions data from all six furnaces equipped with wet venturi
scrubbers to calculate a UPL at the 99-percent confidence level for HCl
and HF, which resulted in the following limits: 4.4 x 10-\2\
lb of HCl/LT and 1.2 x 10-\2\ lb of HF/LT. For new sources
we used the emissions data from the best performing furnace to
calculate a UPL at the 99-percent confidence level for HCl and HF,
which resulted in the following limits: 4.4 x 10-\4\ lb of
HCl/LT and 3.3 x 10-\4\ lb of HF/LT. Based on this data and
methodology, for existing sources constructed or reconstructed before
May 15, 2023, we are proposing limits of 4.4 x 10-\2\ lb of
HCl/LT of taconite pellets produced and 1.2 x 10-\2\ lb of
HF/LT of taconite pellets produced. For new sources constructed or
reconstructed after May 15, 2023, we are proposing limits of 4.4 x
10-\4\ lb of HCl/LT of taconite pellets produced and 3.3 x
10-\4\ lb of HF/LT of taconite pellets produced.
    We expect that all existing indurating furnaces would be able to
comply with the proposed numerical HF limit for existing sources
without the addition of new controls or control measures; we also
expect that HF emissions from existing sources would incidentally be
reduced by about 38 tons per year due to controls used to comply with
the proposed HCl limits (see discussion below). We expect that most
existing indurating furnaces would be able to comply with the proposed
HCl limit for existing sources without the addition of new controls or
control measures. However, we expect that new add-on controls would be
necessary at two existing indurating furnaces (that is, the two
indurating furnaces currently equipped with dry ESPs) to comply with
the proposed HCl limit for existing sources. The estimated total
capital costs for installing the add-on controls necessary to meet the
proposed HCl limit for existing sources is $1.1 million, and the total
annual costs are estimated to be $1.4 million. We estimate that HCl
emissions would be reduced by 713 tons per year. This results in an
estimated cost effectiveness of about $1,940 per ton of HCl removed.
The results of the cost analyses indicate that the estimated cost
effectiveness is within the range of values that the EPA has previously
considered to be cost-effective for many different HAP. Detailed
information on the methodology used to develop the proposed emission
standards and costs are provided in the memorandum Revised Technology
Review of Acid Gas Controls for Indurating Furnaces in the Taconite
Iron Ore Processing Source Category, which is available in the docket
for this action (Docket ID No. EPA-HQ-OAR-2017-0664). We request
comment on our proposal to change the way we regulate HCl and HF
emissions from the source category. Specifically, we request comment on
our proposal to directly regulate HCl and HF emissions from the source
category and the numerical emission limits proposed for HCl and HF.

C. What performance testing are we proposing?

    We are proposing that new and existing sources demonstrate
compliance with the mercury, HCl, and HF standards by performing
initial performance testing and that the performance testing be
repeated at the same frequency as required for the existing PM
standards (i.e., at least twice per title V permit term; that is at
least twice every 5 years as allowed under 40 CFR 63.9630). Existing
sources constructed or reconstructed before May 15, 2023 would be
required to demonstrate initial compliance no later than 180 calendar
days after the compliance date. New sources constructed or
reconstructed before May 15, 2023 would be required to complete the
initial performance testing within 180 days after startup. We are
proposing the performance tests for mercury be performed using EPA
Method 29 and that performance tests for HCl and HF be performed using
EPA Methods 26A. We considered allowing Method 30B as an alternative
method for mercury performance testing. However, we expect that Method
30B may not work well at the low expected concentrations of mercury and
that the relatively high PM in the sample might interfere with Method
30B. We request comment on whether to allow Method 30B as an
alternative performance testing method for mercury.
    During the initial and subsequent performance tests, we are
proposing that testing be completed on every stack associated with each
indurating furnace within 7 calendar days, to the extent practicable,
such that the operating characteristics of the furnace and associated
control device (where applicable) remain representative and consistent
for the duration of the performance test and under normal operating
conditions. These testing requirements are consistent with the testing
requirements for PM in the existing NESHAP (see 40 CFR 63.9620 and
63.9630).

D. What operating limits and monitoring requirements are we proposing?

    In addition to performance testing, we are proposing owners and
operators establish operating limits for the parameters listed in Table
3 for each control device used to comply with the mercury, HCl, and HF
limits. We are proposing to require owners and operators to establish
dry sorbent injection rate operating limits for dry sorbent injection
systems used to comply with the HCl and HF limits, activated carbon
injection rates for activated carbon injection systems used to comply
with mercury limits, and pH operating limits for wet scrubbers used to
comply with the HCl and HF limits (in addition to the requirements in
the current NESHAP to establish pressure drop and scrubber water flow
rate for wet scrubbers used to comply with the PM limits). The
operating limits would be established during the most recent
performance testing where compliance with the emissions limit is
demonstrated. Parametric monitoring would be required to ensure the
control devices operate properly and the source complies with the
emissions limits on a continuous basis. This approach is consistent
with the current requirements for demonstrating compliance with the
existing PM emissions limits. The operating limits for the parameters
listed in Table 3 would be set as the average of the measured parameter
during the three test runs of the most recent performance

test. Owners and operators would be required to comply with the
existing provisions for installation, operation, and preventive
maintenance of APCD and monitoring equipment. Owners and operators
would be required to prepare a preventive maintenance plan, take
corrective action if an air pollution control device exceeds the
established operating limit, and prepare and keep records of
calibration and accuracy checks of the continuous parameter monitoring
systems (CPMS) to document proper operation and maintenance of each
monitoring system.

      Table 3--Proposed Operating Limits and Parametric Monitoring
          Requirements for Demonstrating Continuous Compliance
------------------------------------------------------------------------
                                   Establish a          Demonstrate
        For each . . .          minimum operating  continuous compliance
                                 limit for . . .          by . . .
------------------------------------------------------------------------
Wet Scrubber..................  pH...............  Maintain the daily
                                                    average pH equal to
                                                    or greater than the
                                                    pH operating limit
                                                    established during
                                                    the most recent
                                                    performance test.
Dry sorbent injection system..  Sorbent injection  Maintain the daily
                                                    average dry sorbent
                                                    flow rate equal to
                                                    or greater than the
                                                    flow rate operating
                                                    limit established
                                                    during the most
                                                    recent performance
                                                    test.
Activated carbon injection....  Activated carbon   Maintain the daily
                                 injection.         average activated
                                                    carbon injection
                                                    flow rate equal to
                                                    or greater than the
                                                    flow rate operating
                                                    limit established
                                                    during the most
                                                    recent performance
                                                    test.
------------------------------------------------------------------------

E. What recordkeeping and reporting requirements are we proposing?

    We are proposing facilities would be required to submit the
notifications required in 40 CFR 63.9640; report the results of initial
and subsequent compliance stack testing for mercury, HCl and HF;
maintain monitoring records to demonstrate compliance with the proposed
operating limits for air pollution control devices; comply with the
recordkeeping requirements in 40 CFR 63.9642; and comply with the
reporting requirements in 40 CFR 63.9641, including the requirement to
report deviations from the proposed requirements in the semi-annual
report and to submit corrective action reports. Facilities that elect
to comply with the mercury emissions standard using emissions averaging
would be required to also submit an implementation plan in accordance
with the proposed provisions in 40 CFR 63.9623(d)(1); maintain a copy
of the approved implementation plan; and maintain monthly records of
the quantity of taconite pellets produced by each furnace included in
the emission average and the calculated average mercury emissions.

F. What are the results of any risk analyses completed for this action?

    In the July 28, 2020, final Taconite Iron Ore Processing RTR rule
(85 FR 45476), the EPA conducted a residual risk assessment and
determined that risk from the Taconite Iron Ore Processing source
category was acceptable and the standards provided an ample margin of
safety to protect public health (see Docket Item No. EPA-HQ-OAR-2017-
0664-0163), and the EPA therefore did not promulgate standards to
reduce risk further. Since the final rule, the EPA received new
facility operation and HAP emissions data from all seven operational
major source facilities through the 2022 CAA section 114 information
request and facility stack testing. Specifically, these facilities
completed stack testing and submitted emissions data for PM, metal HAP,
HCl and HF for seven indurating furnaces. The EPA used the new
emissions data that were collected to develop updated estimates of HAP
emissions from indurating furnaces for each of these facilities.
Detailed information on the new emissions data is provided in the
memorandum Emissions Data Collected in 2022 for Indurating Furnaces
Located at Taconite Iron Ore Processing Plants, which is available in
the docket for this action (Docket ID No. EPA-HQ-OAR-2017-0664).
    To determine whether these new HAP emissions estimates would
significantly alter our previous estimates of the human health risk
posed by the Taconite Iron Ore Processing source category, we performed
a baseline (baseline means prior to any controls proposed in this
action) risk analysis using the updated emissions. The methodologies
used for this risk analysis are the same as those described in section
III.C. of the preamble to the September 25, 2019, proposed rule
``National Emission Standards for Hazardous Air Pollutants: Taconite
Iron Ore Processing Residual Risk and Technology Review'' (84 FR
50660). We present the results of the new risk analysis in Table 4 of
this preamble (rows labelled ``Updated Source Category'' and ``Updated
Whole Facility'') and in more detail in the document Taconite Iron Ore
Processing 2023 Risk Analysis Report, available in the docket for this
action (Docket ID No. EPA-HQ-OAR-2017-0664). The risk analysis results
from the July 28, 2020, final Taconite Iron Ore Processing RTR rule (85
FR 45476) are also provided in Table 4 for comparison (rows labelled
``Final Rule Source Category'' and ``Final Rule Whole Facility'').

 Table 4--Comparison of Taconite Iron Ore Processing Source Category Baseline Inhalation Risk Assessment Results From the 7/28/20 Final Rule to the 2023
                                                                     Updated Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
                               Maximum individual cancer risk (in  Estimated population    Estimated annual       Maximum chronic     Maximum  screening
                                         1 million) \3\            at increased risk of    cancer incidence     noncancer TOSHI \1\  acute  noncancer HQ
                              ------------------------------------    cancer >=1-in-1      (cases per year)   ----------------------         \2\
                                                                          million       ----------------------                      --------------------
       Risk assessment                               Based on     ----------------------                        Based on   Based on
                                Based on actual      allowable      Based on   Based on   Based on   Based on    actual   allowable    Based on actual
                                   emissions         emissions       actual   allowable    actual   allowable  emissions  emissions       emissions
                                                                   emissions  emissions  emissions  emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Final Rule Source Category...  3 (As, Ni, Be)..  5 (As, Ni, Be)..     38,000     43,000      0.001      0.001   0.2 (Mn)   0.2 (Mn)  HQREL = <1 (As)
Updated Source Category \4\..  5 (As, Ni, Be)..  6 (As, Ni, Be)..     56,000     56,400      0.002      0.003   0.1 (Mn)   0.2 (Mn)  HQREL = 1 (As)
Final Rule Whole Facility....  3 (As, Ni, Be)..  ................     40,000  .........      0.001  .........   0.2 (Mn)  .........  ...................

Updated Whole Facility \4\...  5 (As, Ni, Be)..  ................     56,000  .........      0.002  .........   0.2 (Mn)  .........  ...................
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ The TOSHI is the sum of the chronic noncancer hazard quotients (HQs) for substances that affect the same target organ or organ system.
\2\ The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop HQ values.
\3\ Five facilities contribute to the maximum individual risk (MIR)--Keetac, Hibbing, Minorca, UTAC, and Minntac.
\4\ Includes updated emissions data received following proposal from the 2022 CAA section 114 information request and any testing data received after
  publication of the RTR final rule.

    The results of the revised inhalation risk modeling, as shown in
Table 4 of this preamble, indicate that the cancer risk estimates for
the Taconite Iron Ore Processing source category increased slightly
from the estimate in the RTR final rule. Specifically, the maximum
individual cancer risk (MIR) based on actual emissions (lifetime)
increased from 3-in-1 million to 5-in-1 million (driven by arsenic,
beryllium and nickel from fugitive dust sources and indurating
furnaces). The number of people with chronic cancer risks of greater
than or equal to 1-in-1 million increased from 38,000 to 56,000. The
total estimated annual cancer incidence (national) based on actual
emission levels increased from 0.001 to 0.002 excess cancer cases per
year. The maximum chronic noncancer target organ-specific hazard index
(TOSHI) value based on actual emissions decreased from 0.2 to 0.1
(neurological; driven by manganese compounds from fugitive dust and ore
crushing sources). The maximum screening acute noncancer HQ value (off-
facility site) remained about 1 (driven by arsenic from fugitive dust
and ore crushing sources).
    Regarding multipathway risk, in the July 28, 2020, final Taconite
Iron Ore Processing RTR rule (85 FR 45476), we concluded that there was
``no significant potential for multipathway health effects.'' This
determination was based upon a site-specific multipathway assessment
that found cancer risk based on the fisher scenario was 0.2-in-1
million (arsenic). In addition, the noncancer hazard quotients were
less than 1 for mercury (0.02) and for cadmium (0.01). We performed a
linear scaling of the multipathway risks using a conservatively high
estimate of the revised emissions for arsenic (4.4 times increase in
emissions), mercury (2.4 times increase in emissions) and cadmium
(emissions decreased). Using these scaling factors, the adjusted
multipathway risks for cancer increased to 0.9-in-1 million (arsenic),
and the adjusted noncancer hazard quotient for mercury increased to
0.05 (arsenic was unchanged).
    The results of the updated inhalation risk analysis and the updated
multipathway risk assessment indicate that the risk for the Taconite
Iron Ore Processing source category has increased slightly, but still
remains well within the range of acceptability. Further, we have not
identified any information that would change the ample margin of safety
analysis finalized in the 2020 RTR final rule. Based on these results,
we are not proposing any changes to our decisions regarding risk
acceptability or ample margin of safety that were made under CAA
section 112(f) in the July 28, 2020, Taconite Iron Ore Processing RTR
final rule (85 FR 45476).

G. What other actions are we proposing?

    On January 5, 2022, the EPA published in the Federal Register (87
FR 393) a final rule amending the list of HAP under the CAA to add 1-
bromopropane (1-BP) in response to public petitions previously granted
by the EPA. As each NESHAP is reviewed, we are evaluating whether the
addition of 1-BP to the CAA section 112 HAP list impacts the source
category. For the Taconite Iron Ore Processing source category, we
conclude that the inclusion of 1-BP as a HAP will not impact the NESHAP
because, based on available information, we expect that 1-BP is not
emitted from this source category. As a result, no changes are being
proposed to the rule based on the addition of 1-BP to the CAA section
112 HAP list. Nevertheless, we are requesting comments and data
regarding any potential emissions of 1-BP from this source category.
    Also, in addition to the proposed actions described above, we are
proposing to update the electronic reporting requirements found in 40
CFR 63.9641(c) and 40 CFR 63.9641(f)(3) to reflect new procedures for
reporting CBI. Specifically, we are proposing to include an email
address that owners and operators may use to electronically submit
compliance reports containing CBI to the OAQPS CBI Office.

H. What compliance dates are we proposing?

    The amendments to the Taconite Iron Ore Processing NESHAP proposed
in this rulemaking for adoption of mercury standards under CAA sections
112(d)(2) and (3) and adoption of HCl and HF standards under CAA
section 112(d)(6) are subject to the compliance deadlines outlined in
the CAA under section 112(i). For existing sources, CAA section
112(i)(3) requires compliance ``as expeditiously as practicable, but in
no event later than 3 years after the effective date of such standard''
subject to certain exemptions further detailed in the statute.\12\ In
determining what compliance period is as ``expeditious as
practicable,'' we consider the amount of time needed to plan and
construct projects and change operating procedures. The EPA projects
that several existing sources would need to install new add-on controls
to comply with the proposed mercury limits; we also expect that one or
two facilities will need to install controls for acid gases. We expect
that these sources will require substantial time to plan, design,
construct, and begin operating the new add-on controls, and to conduct
performance testing, and implement monitoring to comply with the
revised provisions. Therefore, we are proposing to allow 3 years for
existing sources constructed or reconstructed before May 15, 2023 to
become compliant with the new emission standards for mercury, HCl and
HF. These sources would have

to continue to meet the current provisions of 40 CFR part 63, subpart
RRRRR.
---------------------------------------------------------------------------

    \12\ Association of Battery Recyclers v. EPA, 716 F.3d 667, 672
(D.C. Cir. 2013) (``Section 112(i)(3)'s 3-year maximum compliance
period applies generally to any emission standard . . . promulgated
under [section 112]'' (brackets in original)).
---------------------------------------------------------------------------

    Pursuant to CAA section 112(i), we are proposing that all affected
sources that commenced construction or reconstruction after May 15,
2023 would comply with the provisions by the effective date of the
final rule or upon startup, whichever is later. The final action is not
a ``major rule'' as defined by 5 U.S.C. 804(2), so the effective date
of the final rule will be the promulgation date as specified in CAA
section 112(d)(10).
    We solicit comment on these proposed compliance periods, and we
specifically request submission of information from sources in this
source category regarding specific actions that would need to be
undertaken to comply with the proposed standards and the time needed to
make the adjustments for compliance with any of the proposed standards.
We note that information provided may result in changes to the proposed
compliance dates.

V. Summary of Cost, Environmental, and Economic Impacts

A. What are the affected sources?

    As previously indicated, there are currently seven major sources
subject to the Taconite Iron Ore Manufacturing NESHAP that are
operating in the United States. One additional major source, Empire
Mining, is subject and has a permit to operate, but has been
indefinitely idled since 2016. The NESHAP for Taconite Iron Ore
Processing applies to the owner or operator of a taconite iron ore
processing plant that is (or is part of) a major source of HAP
emissions. A taconite iron ore processing plant is any facility engaged
in separating and concentrating iron ore from taconite ore to produce
taconite pellets. Taconite iron ore processing includes the following
processes: liberation of the iron ore by wet or dry crushing and
grinding in gyratory crushers, cone crushers, rod mills, and ball
mills; concentration of the iron ore by magnetic separation or
flotation; pelletizing by wet tumbling with a balling drum or balling
disc; induration using a straight grate or grate kiln indurating
furnace; and finished pellet handling. A major source of HAP is a plant
site that emits, or has the potential to emit, any single HAP at a rate
of 9.07 megagrams (10 tons) or more, or any combination of HAP at a
rate of 22.68 megagrams (25 tons) or more per year from all emission
sources at the plant site.

B. What are the air quality impacts?

    This action proposes first-time emissions standards for mercury and
revised emissions standards for HCl and HF and would require some
plants to install additional controls on their indurating furnaces. For
HCl, HF and mercury, installation of controls will result in a combined
reduction of total HAP of 751 tons of HAP per year (tpy). Specifically,
we estimate that the installation of controls will reduce HCl and HF
emissions by 713 tpy and 38 tpy, respectively, and will reduce mercury
emissions by 497 pounds per year (0.25 tpy).
    Indirect or secondary air emissions impacts are impacts that would
result from the increased electricity usage associated with the
operation of control devices (e.g., increased secondary emissions of
criteria pollutants from power plants). Energy impacts consist of the
electricity and steam needed to operate control devices and other
equipment. We find that the secondary impacts of this action are
minimal. Refer to the memorandum Development of Impacts for the
Proposed Amendments to the NESHAP for Taconite Iron Ore Processing for
a detailed discussion of the analyses performed on emissions reductions
and potential secondary impacts. This memorandum is available in the
docket for this action (Docket ID No. EPA-HQ-OAR-2017-0664).

C. What are the cost impacts?

    This action proposes emission limits for new and existing sources
in the Taconite Iron Ore Processing source category. Although this
action contains requirements for new sources, we are not aware of any
new sources being constructed now or planned in the next year, and,
consequently, we did not estimate any cost impacts for new sources. We
estimate the total capital and annualized costs of the proposed rule
for existing sources in the Taconite Iron Ore Processing source
category will be approximately $91 million and $54 million per year,
respectively. The annual costs are based on operation and maintenance
of added control systems. A memorandum titled Development of Impacts
for the Proposed Amendments to the NESHAP for Taconite Iron Ore
Processing includes details of our cost assessment, expected emission
reductions and estimated secondary impacts. A copy of this memorandum
is available in the docket for this action (Docket ID No. EPA-HQ-OAR-
2017-0664).

D. What are the economic impacts?

    For the proposed rule, the EPA estimated the cost of installing
additional APCD in order to comply with the proposed emission limits.
This includes the capital costs of the initial installation, and
subsequent maintenance and operation of the controls. To assess the
potential economic impacts, the expected annual cost was compared to
the total sales revenue for the ultimate owners of affected facilities.
For this rulemaking, the expected annual cost is $8 million (on
average) for each facility, with an estimated nationwide annual cost of
$54 million per year. The seven affected facilities are owned by two
parent companies (U.S. Steel and Cleveland-Cliffs, Inc.). Neither
parent company qualifies as a small business, and the total costs
associated with the proposed amendments are expected to be less than 1
percent of annual sales revenue per ultimate owner.
    The EPA also modeled the impacts of the proposed amendments using
two standard partial equilibrium economic models: one for taconite iron
ore pellets and one for steel mill products. The EPA linked these two
partial equilibrium models by specifying interactions between supply
and demand in both markets and solving for changes in prices and
quantity across both markets simultaneously. These models use baseline
economic data from 2019 to project the impact of the proposed NESHAP
amendments on the market for taconite iron ore pellets and steel mill
products. The models allow the EPA to project facility- and market-
level price and quantity changes for taconite iron ore pellets and
market-level price and quantity changes for steel mill products,
including changes in imports and exports in both markets. Under the
proposed amendments, the models project a 0.26 percent fall in the
quantity of domestically produced taconite iron ore pellets along with
a 0.58 percent increase in their price. The models also project a 0.02
percent fall in the quantity of domestically produced steel mill
products along with an 0.01 percent increase in their price.
    Information on our economic impact estimates on the sources in the
Taconite Iron Ore Processing source category is available in the
document Economic Impact Analysis for the Proposed National Emission
Standards for Hazardous Air Pollutants: Taconite Iron Ore Processing
Amendments (EIA), available in the docket for this action (Docket ID
No. EPA-HQ-OAR-2017-0664). The EIA also includes an analysis of less
and more stringent alternative

regulatory options for mercury and acid gases.

E. What analysis of environmental justice did we conduct?

    Consistent with the EPA's commitment to integrating environmental
justice (EJ) in the Agency's actions, and following the directives set
forth in multiple Executive orders, the Agency has evaluated the
impacts of this action on communities with EJ concerns. Overall, we
found that in the population living in close proximity of facilities,
the following demographic groups were above the national average:
White, Native American, and people living below the poverty level. For
two facilities, the percentage of the population that is Native
American was more than double the national average.
    Executive Order 12898 directs the EPA to identify the populations
of concern who are most likely to experience unequal burdens from
environmental harms, which are specifically minority populations
(people of color), low-income populations, and indigenous peoples (59
FR 7629; February 16, 1994). Additionally, Executive Order 13985 is
intended to advance racial equity and support underserved communities
through Federal Government actions (86 FR 7009; January 20, 2021). The
EPA defines EJ as ``the fair treatment and meaningful involvement of
all people regardless of race, color, national origin, or income, with
respect to the development, implementation, and enforcement of
environmental laws, regulations, and policies.'' \13\ The EPA further
defines fair treatment to mean that ``no group of people should bear a
disproportionate burden of environmental harms and risks, including
those resulting from the negative environmental consequences of
industrial, governmental, and commercial operations or programs and
policies.''
---------------------------------------------------------------------------

    \13\ https://www.epa.gov/environmentaljustice.
---------------------------------------------------------------------------

    For the Taconite Iron Ore Processing source category, the EPA
examined the potential for EJ concerns by conducting a proximity
demographic analysis. The proximity demographic analysis is an
assessment of individual demographic groups in the total population
living within 10 kilometers (km) and 50 km of the facilities. The EPA
then compared the data from this analysis to the national average for
each of the demographic groups. Since the taconite iron ore processing
facilities are very large, a radius of 10 km was used as the near
facility distance for the proximity analysis. A distance closer than 10
km does not yield adequate population size for the results. The results
of the proximity analysis are in the technical report Analysis of
Demographic Factors For Populations Living Near Taconite Iron Ore
Processing Source Category Operations, available in the docket for this
action (Docket ID No. EPA-HQ-OAR-2017-0664).
    The results in Table 5 show that for the population living within
10 km of the eight facilities, the following demographic groups were
above the national average: White (93 percent versus 60 percent
nationally), Native American (0.8 percent versus 0.7 percent
nationally), and people living below the poverty level (15 percent
versus 13 percent nationally). For two facilities, the percentage of
the population living within 10 km that is Native American (1.9 percent
and 2.3 percent) was more than double the national average (0.7
percent).

     Table 5--Taconite Iron Ore Processing Source Category Proximity
                           Demographic Results
------------------------------------------------------------------------
                                                       Total population
                                                       living within 10
        Demographic group             Nationwide        km of taconite
                                                          facilities
------------------------------------------------------------------------
Total Population................  328M..............  59,000.
Number of Facilities............  ..................  8.
------------------------------------------------------------------------
            Race and Ethnicity by Percent [Number of people]
------------------------------------------------------------------------
White...........................  60 percent [197M].  93 percent
                                                       [54,900].
African American................  12 percent [40M]..  1 percent [600].
Native American.................  0.7 percent [2M]..  0.8 percent [500].
Hispanic or Latino (includes      19 percent [62M]..  0.9 percent [500].
 white and nonwhite).
Other and Multiracial...........  8 percent [27M]...  4 percent [2,400].
------------------------------------------------------------------------
                  Income by Percent [Number of People]
------------------------------------------------------------------------
Below Poverty Level.............  13 percent [44M]..  15 percent
                                                       [9,000].
Above Poverty Level.............  87 percent [284M].  85 percent
                                                       [50,000].
------------------------------------------------------------------------
                 Education by Percent [Number of People]
------------------------------------------------------------------------
Over 25 and without a High        12 percent [40M]..  6 percent [3,600].
 School Diploma.
Over 25 and with a High School    88 percent [288M].  94 percent
 Diploma.                                              [55,400].
------------------------------------------------------------------------
          Linguistically Isolated by Percent [Number of People]
------------------------------------------------------------------------
Linguistically Isolated.........  5 percent [18M]...  0.4 percent [200].
------------------------------------------------------------------------
Notes:
 Nationwide population and demographic percentages are based on
  Census' 2015-2019 ACS 5-year block group averages. Total population
  count within 10km is based on 2010 Decennial Census block population.
 To avoid double counting, the ``Hispanic or Latino'' category
  is treated as a distinct demographic category. A person who identifies
  as Hispanic or Latino is counted as Hispanic/Latino, regardless of
  race.
 The sum of individual populations with a demographic category
  may not add up to total due to rounding.

    The proposed actions, if finalized, will ensure compliance via
frequent compliance testing and monitoring of control device operating
parameters, and reduce emissions via new standards for mercury and
revised standards for HCl and HF and by requiring affected sources to
meet all the emissions standards at all times (including periods of
startup, shutdown, and malfunctions). Therefore, the EPA expects that
there would be a positive, beneficial effect for all populations in
proximity to affected sources, including in communities potentially
overburdened by pollution, which are often minority, low-income and
indigenous communities.

F. What analysis of children's environmental health did we conduct?

    In the July 28, 2020, final Taconite Iron Ore Processing RTR rule
(85 FR 45476), the EPA conducted a residual risk assessment and
determined that risk from the Taconite Iron Ore Processing source
category was acceptable, and the standards provided an ample margin of
safety to protect public health (see Docket Item No. EPA-HQ-OAR-2017-
0664-0163). For this rulemaking, we updated that risk analysis using
new emissions data that the EPA received for some HAP emissions sources
at the taconite facilities. We determined that these new HAP emissions
estimates would not significantly change our previous estimates of the
human health risk posed by the Taconite Iron Ore Processing source
category (see section IV.F of this preamble). In addition, this action
proposes first-time emissions standards for mercury and revised
emissions standards for HCl and HF and would further reduce emissions.
Specifically, we estimate that the installation of controls will reduce
HCl and HF emissions by 713 tpy and 38 tpy, respectively, and will
reduce mercury emissions by 497 pounds per year (0.25 tpy).
    This action's health and risk assessments are protective of the
most vulnerable populations, including children, due to how we
determine exposure and through the health benchmarks that we use.
Specifically, the risk assessments we perform assume a lifetime of
exposure, in which populations are conservatively presumed to be
exposed to airborne concentrations at their residence continuously, 24
hours per day for a 70-year lifetime, including childhood. With regards
to children's potentially greater susceptibility to noncancer
toxicants, the assessments rely on the EPA's (or comparable) hazard
identification and dose-response values that have been developed to be
protective for all subgroups of the general population, including
children. For more information on the risk assessment methods, see the
risk report for the July 28, 2020, final Taconite RTR rule (85 FR
45476), which is available in the docket (Docket ID No. EPA-HQ-OAR-
2017-0664).

VI. Request for Comments

    We solicit comments on this proposed action. In addition to general
comments on this proposed action, we request comment on our proposal to
set mercury emission limits at the MACT floor level. We also request
comment on whether to allow sources to comply with the mercury MACT
standards through the proposed emissions averaging compliance
alternative and on the appropriate adjustment factor to apply under the
emissions averaging compliance alternative. In addition, we request
comment and data on the variation of mercury content in taconite ore
and whether and to what extent this variation should be considered in
the development of the MACT standards for mercury from indurating
furnaces. We also solicit comment on the data submitted by AISI and
U.S. Steel concerning variation of mercury content in taconite ore (see
discussion in section IV.A. of this preamble). In addition, we request
comment on whether we should allow use of EPA Method 30B for affected
facilities to demonstrate compliance with the proposed MACT standards
for mercury. Further, we request comment on our proposal to change the
way we regulate HCl and HF emissions from the source category.
Specifically, we request comment on our proposal to directly regulate
HCl and HF emissions from the source category and the numerical
emission limits proposed for HCl and HF.

VII. Submitting Data Corrections

    The site-specific emissions data used in developing the proposed
MACT standards for HCl, mercury, and HF, as emitted from the Taconite
Iron Ore Processing source category, are provided in the docket for
this action (Docket ID No. EPA-HQ-OAR-2017-0664).
    If you believe that the data are not representative or are
inaccurate, please identify the data in question, provide your reason
for concern, and provide any ``improved'' data that you have, if
available. When you submit data, we request that you provide
documentation of the basis for the revised values to support your
suggested changes.
    For information on how to submit comments, including the submittal
of data corrections, refer to the instructions provided in the
introduction of this preamble.

VIII. Statutory and Executive order Reviews

    Additional information about these statutes and Executive orders
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    This action is not a significant regulatory action and was
therefore not submitted to the Office of Management and Budget (OMB)
for review.

B. Paperwork Reduction Act (PRA)

    The information collection activities in this proposed rule have
been submitted for approval to the Office of Management and Budget
(OMB) under the PRA. The Information Collection Request (ICR) document
that the EPA prepared has been assigned EPA ICR number 2050.10. You can
find a copy of the ICR in the docket for this action, and it is briefly
summarized here.
    We are proposing changes to the reporting and recordkeeping
requirements for the Taconite Iron Ore Processing NESHAP by
incorporating the reporting and recordkeeping requirements associated
with the new and existing source MACT standards for mercury and
revising the emission standards for HCl and HF.
    Respondents/affected entities: Owners or operators of taconite iron
ore plants that are major sources, or that are located at, or are part
of, major sources of HAP emissions.
    Respondent's obligation to respond: Mandatory (40 CFR part 63,
subpart RRRRR).
    Estimated number of respondents: On average over the next 3 years,
approximately seven existing major sources will be subject to these
standards. It is also estimated that no additional respondent will
become subject to the emission standards over the 3-year period.
    Frequency of response: The frequency of responses varies depending
on the burden item.
    Total estimated burden: The average annual burden to industry over
the next 3 years from the proposed recordkeeping and reporting
requirements is estimated to be 1,580 hours per year. Burden is defined
at 5 CFR 1320.3(b).
    Total estimated cost: The annual recordkeeping and reporting cost
for all facilities to comply with all the

requirements in the NESHAP is estimated to be $177,000 per year. The
average annual recordkeeping and reporting cost for this rulemaking is
estimated to be $25,000 per facility per year.
    An agency may not conduct or sponsor, and a person is not required
to respond to, a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for the
EPA's regulations in 40 CFR are listed in 40 CFR part 9.
    Submit your comments on the Agency's need for this information, the
accuracy of the provided burden estimates and any suggested methods for
minimizing respondent burden to the EPA using the docket identified at
the beginning of this proposed rule. The EPA will respond to any ICR-
related comments in the final rule. You may also send your ICR-related
comments to OMB's Office of Information and Regulatory Affairs using
the interface at www.reginfo.gov/public/do/PRAMain. Find this
particular information collection by selecting ``Currently under
Review--Open for Public Comments'' or by using the search function. OMB
must receive comments no later than July 14, 2023.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action will not impose any requirements on small entities. The Agency
confirmed through responses to a CAA section 114 information request
that there are only seven taconite iron ore processing plants currently
operating in the United States and that these plants are owned by two
parent companies that do not meet the definition of small businesses,
as defined by the U.S. Small Business Administration.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate of $100 million or
more as described in UMRA, 2 U.S.C. 1531-1538, and does not
significantly or uniquely affect small governments. This action imposes
no enforceable duty on any state, local, or tribal governments or the
private sector.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national Government and the states, or on the distribution of power
and responsibilities among the various levels of Government.

F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

    This action does not have tribal implications as specified in
Executive Order 13175. None of the taconite iron ore processing plants
are owned or operated by Indian tribal governments. Thus, Executive
Order 13175 does not apply to this action.
    Consistent with the EPA Policy on Consultation and Coordination
with Indian Tribes, the EPA consulted with tribal officials during the
development of this action. On January 12, 2022, the EPA's Office of
Air and Radiation held a Tribal consultation meeting with
representatives from the Fond du Lac Band of Lake Superior Chippewa
Reservation and the Leech Lake Band of Ojibwe Reservation to discuss
the EPA's CAA section 114 information request, and the general plans
for this proposed rulemaking and related issues. A summary of that
consultation is provided in the document Consultation with the Fond du
Lac Band of Lake Superior Chippewa and the Leech Lake Band of Ojibwe
regarding Notice of Proposed Rulemaking for the National Emission
Standards for Hazardous Air Pollutants for Taconite Iron Ore Processing
Amendments on January 12, 2022, which is available in the docket for
this action. Furthermore, EPA staff attended several meetings hosted by
the Minnesota Pollution Control Agency (MPCA), along with
representatives from Tribal Nations, MPCA, the Michigan Attorney
General's Office, the Minnesota Attorney General's Office,
EarthJustice, and the Michigan Department of Environment, Great Lakes,
and Energy, to discuss concerns related to HAP emissions from taconite
iron ore processing facilities. In addition, the EPA received letters
from representatives of the Leech Lake Band of Ojibwe and the Fond du
Lac Band of Lake Superior Chippewa expressing concerns of these Tribal
Nations due to HAP emissions from the taconite iron ore processing
facilities. These letters, and responses from the EPA, are provided in
the docket for this action (Docket ID No. EPA-HQ-OAR-2017-0664).

G. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks

    Executive Order 13045 (62 FR 19885; April 23, 1997) directs Federal
agencies to include an evaluation of the health and safety effects of
the planned regulation on children in Federal health and safety
standards and explain why the regulation is preferable to potentially
effective and reasonably feasible alternatives. This action is not
subject to Executive Order 13045 because it is not economically
significant as defined in Executive Order 12866, and because the EPA
does not believe the environmental health or safety risks addressed by
this action present a disproportionate risk to children. In this action
the EPA proposes emission standards for one previously unregulated
pollutant (mercury) and revised emissions standards for two currently
regulated pollutants (HCl and HF). Therefore, the rulemaking proposes
health benefits to children by reducing the level of HAP emissions
emitted from taconite iron ore processing plants.
    However, the EPA's Policy on Children's Health applies to this
action. This action is subject to the EPA's Policy on Children's Health
\14\ because the proposed rule has considerations for human health.
Information on how the policy was applied is available in section V.F
``What analysis of children's environmental health did we conduct'' of
this preamble.
---------------------------------------------------------------------------

    \14\ https://www.epa.gov/children/childrens-health-policy-and-plan.
---------------------------------------------------------------------------

H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use

    This action is not a ``significant energy action'' because it is
not likely to have a significant adverse effect on the supply,
distribution, or use of energy. In this action, the EPA is proposing to
set emission standards for one previously unregulated pollutant
(mercury) and to revise emission standards for two currently regulated
pollutants (HCl and HF). This does not impact energy supply,
distribution, or use.

I. National Technology Transfer and Advancement Act (NTTAA) and 1 CFR
Part 51

    This action involves technical standards. Therefore, the EPA
conducted searches for the Taconite Iron Ore Processing NESHAP through
the Enhanced National Standards Systems Network (NSSN) Database managed
by the American National Standards Institute (ANSI). We also conducted
a review of voluntary consensus standards (VCS) organizations and
accessed and searched their databases. We conducted searches for EPA
Methods 1, 1A, 2, 2A, 2C, 2D, 2F, 2G, 3, 3A, 3B, 4, 5, 5D, 17, 26A and
29. During the EPA's VCS

search, if the title or abstract (if provided) of the VCS described
technical sampling and analytical procedures that are similar to the
EPA's reference method, the EPA ordered a copy of the standard and
reviewed it as a potential equivalent method. We reviewed all potential
standards to determine the practicality of the VCS for this proposed
rule. This review requires significant method validation data that meet
the requirements of EPA Method 301 for accepting alternative methods or
scientific, engineering, and policy equivalence to procedures in the
EPA referenced methods. The EPA may reconsider determinations of
impracticality when additional information is available for any
particular VCS.
    No voluntary consensus standards were identified for EPA Methods 1,
1A, 2, 2A, 2C, 2D, 2F, 2G, 3, 3A, 4, 5, 5D, 17 or 26A. Two voluntary
consensus standards were identified as acceptable alternatives to EPA
Methods 3B and 29.
    The EPA proposes to allow use of the VCS ANSI/ASME PTC 19.10-1981
Part 10 (2010), ``Flue and Exhaust Gas Analyses'' as an acceptable
alternative to EPA Method 3B for the manual procedures only and not the
instrumental procedures. The ANSI/ASME PTC 19.10-1981 Part 10 method
incorporates both manual and instrumental methodologies for the
determination of oxygen content. The manual method segment of the
oxygen determination is performed through the absorption of oxygen.
This method is available at the American National Standards Institute
(ANSI), 1899 L Street NW, 11th Floor, Washington, DC 20036 and the
American Society of Mechanical Engineers (ASME), Three Park Avenue, New
York, NY 10016-5990. See https://www.ansi.org and https://www.asme.org.
The standard is available to everyone at a cost determined by ANSI/ASME
($96). The cost of obtaining this method is not a significant financial
burden, making the methods reasonably available.
    The EPA proposes to allow use of the VCS ASTM D6784-16, ``Standard
Test Method for Elemental, Oxidized, Particle-Bound and Total Mercury
in Flue Gas Generated from Coal-Fired Stationary Sources (Ontario Hydro
Method)'' as an acceptable alternative to EPA Method 29 (mercury
portion only) as a method for measuring mercury concentrations ranging
from approximately 0.5 to 100 micrograms per normal cubic meter
([micro]g/Nm\3\). This test method describes equipment and procedures
for obtaining samples from effluent ducts and stacks, equipment and
procedures for laboratory analysis, and procedures for calculating
results. VCS ASTM D6784-16 allows for additional flexibility in the
sampling and analytical procedures from the earlier version of the same
standard VCS ASTM D6784-02 (Reapproved 2008). VCS ASTM D6784-16 allows
for the use of either an EPA Method 17 sampling configuration with a
fixed (single) point where the flue gas is not stratified, or an EPA
Method 5 sampling configuration with a multi-point traverse. For this
action, only the EPA Method 5 sampling configuration with a multi-point
traverse can be used. This method is available at ASTM International,
1850 M Street NW, Suite 1030, Washington, DC 20036. See https://www.astm.org/. The standard is available to everyone at a cost
determined by ASTM ($82). The cost of obtaining this method is not a
significant financial burden, making the method reasonably available.
    Additional detailed information on the VCS search and determination
can be found in the memorandum, Voluntary Consensus Standard Results
for National Emission Standards for Hazardous Air Pollutants: Taconite
Iron Ore Processing, which is available in the docket for this action
(Docket ID No. EPA-HQ-OAR-2017-0664). The EPA welcomes comments on this
aspect of the proposed rulemaking and, specifically, invites the public
to identify potentially applicable VCS and to explain why such
standards should be used in this regulation.
    The EPA is incorporating by reference the VCS ANSI/ASME PTC 19.10-
1981 Part 10 (2010), ``Flue and Exhaust Gas Analyses'' as an acceptable
alternative to EPA Method 3B for the determination of oxygen content
(manual procedures only) and the VCS ASTM D6784-16, ``Standard Test
Method for Elemental, Oxidized, Particle-Bound and Total Mercury in
Flue Gas Generated from Coal-Fired Stationary Sources (Ontario Hydro
Method),'' as an acceptable alternative to EPA Method 29 (mercury
portion only) as a method for measuring elemental, oxidized, particle-
bound, and total mercury.

J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

    Executive Order 12898 (59 FR 7629; February 16, 1994) directs
Federal agencies, to the greatest extent practicable and permitted by
law, to make environmental justice part of their mission by identifying
and addressing, as appropriate, disproportionately high and adverse
human health or environmental effects of their programs, policies, and
activities on minority populations (people of color and/or indigenous
peoples) and low-income populations.
    The EPA anticipates that the human health or environmental
conditions that exist prior to this action result in or have the
potential to result in disproportionate and adverse human health or
environmental effects on low-income populations and/or indigenous
peoples. The assessment of populations in close proximity of taconite
iron ore processing plants shows Native American and low-income
populations are higher than the national average (see section V.F. of
this preamble). The higher percentages are driven by two of the eight
facilities in the source category. The EPA anticipates that this action
is likely to reduce existing disproportionate and adverse effects on
low-income populations and/or indigenous peoples. The EPA is proposing
new MACT standards for mercury and revised standards for HCl and HF.
The EPA expects that five facilities would have to implement control
measures to reduce emissions to comply with the new and revised MACT
standards and that HAP exposures for indigenous peoples and low-income
individuals living near these five facilities would decrease. The
information supporting this Executive order review is contained in
section V.E of this preamble.

List of Subjects in 40 CFR Part 63

    Environmental protection, Air pollution control, Hazardous
substances, Incorporation by reference, Reporting and recordkeeping
requirements.

Michael S. Regan,
Administrator.
[FR Doc. 2023-10068 Filed 5-12-23; 8:45 am]
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