[Federal Register Volume 89, Number 28 (Friday, February 9, 2024)]
[Proposed Rules]
[Pages 9088-9103]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-02299]



[[Page 9088]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2017-0015; FRL-5948.1-02-OAR]
RIN 2060-AV59


National Emission Standards for Hazardous Air Pollutants: Lime 
Manufacturing Plants Amendments

AGENCY: Environmental Protection Agency (EPA).

ACTION: Supplemental notice of proposed rulemaking.

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SUMMARY: This action supplements our proposed amendments to the 
National Emission Standards for Hazardous Air Pollutants for Lime 
Manufacturing Plants (Lime Manufacturing NESHAP) published in the 
Federal Register on January 5, 2023. In that action, the Environmental 
Protection Agency (EPA) proposed hazardous air pollutant (HAP) 
emissions standards for the following pollutants: hydrogen chloride 
(HCl), mercury, total hydrocarbon (THC) as a surrogate for organic HAP, 
and dioxin/furans (D/F). The EPA is proposing revisions to the proposed 
emission limits for HCl, mercury, organic HAP, and D/F based on 
additional information gathered since the publication of the January 5, 
2023, proposed rule amendments. We solicit comments on all aspects of 
this proposed action.

DATES: Comments must be received on or before March 11, 2024. 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 March 11, 2024.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed 
action contact U.S. EPA, Attn: Mr. Brian Storey, Mail Drop: D143-04, 
109 T.W. Alexander Drive, P.O. Box 12055, RTP, North Carolina 27711; 
telephone number: (919) 541-1103 and email address: 
[email protected].

SUPPLEMENTARY INFORMATION: 
    Docket. The EPA has established a docket for this rulemaking under 
Docket ID No. EPA-HQ-OAR-2017-0015. 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. 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-
2017-0015. 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 
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-2020-0430. The mailed CBI material should be double wrapped 
and clearly marked. Any CBI markings should not show through the outer 
envelope.

[[Page 9089]]

    Preamble acronyms and abbreviations. Throughout this document 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:

CAA Clean Air Act
CBI Confidential Business Information
CFR Code of Federal Regulations
DB dead burned dolomitic lime
D/F dioxin/furans
DL dolomitic lime
DSI dry sorbent injection
EJ environmental justice
EPA Environmental Protection Agency
ESP electrostatic precipitator
FF fabric filter
FR Federal Register
g/dscm grams of pollutant per dry standard cubic meter of air
HAP hazardous air pollutant(s)
HBEL health-based emission limit
HCl hydrogen chloride
HQ hazard quotient
IQV intra-quarry variability
lb/hr pounds of pollutant per hour
lb/MMton pounds of pollutant per million tons of lime produced at 
the kiln
lb/tsf pounds of pollutant per ton of stone feed
MACT maximum achievable control technology
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
ppmvd parts per million by volume, dry
PR preheater rotary kiln
PRA Paperwork Reduction Act
PSH process stone handling
QL quick lime
RDL representative detection level
REL reference exposure limit
RFA Regulatory Flexibility Act
RfC non-cancer reference concentration
RTR residual risk and technology review
SR straight rotary kiln
SSM startup, shutdown, and malfunction
TEF toxicity equivalence factors
THC total hydrocarbons
tpy tons of pollutant per year
UMRA Unfunded Mandates Reform Act
UPL upper predictive limit
VK vertical kiln
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 changes did we propose for the lime manufacturing source 
category in our January 5, 2023, proposal?
III. Analytical Results and Proposed Decisions
    A. What revisions are we proposing to the hydrogen chloride 
emission standards?
    B. What revisions are we proposing to the mercury emission 
standards?
    C. What revisions are we proposing to the organic HAP emission 
standards?
    D. What revisions are we proposing to the dioxin/furan emission 
standards?
    E. What other actions are we proposing, and what is the 
rationale for those actions?
    F. What revisions are we proposing to the performance testing, 
monitoring, and recordkeeping and reporting requirements?
    G. What revisions to the compliance dates are we proposing?
IV. Summary of Cost, Environmental, and Economic Impacts and 
Additional Analyses Conducted
    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 are the benefits?
    F. What analysis of environmental justice did we conduct?
    G. What analysis of children's environmental health did we 
conduct?
V. Request for Comments
VI. Submitting Data Corrections
VII. Statutory and Executive Order Review
    A. Executive Order 12866: Regulatory Planning and 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 and Executive Order 14096: Revitalizing our Nation's 
Commitment to Environmental Justice for All

I. General Information

A. Does this action apply to me?

    Table 1 of this preamble lists the NESHAP and associated regulated 
industrial source categories that are the subject of this supplemental 
proposal. Table 1 is not intended to be exhaustive, but rather provides 
a guide for readers regarding the entities that the proposed rule is 
likely to affect. The standards, if promulgated, will be directly 
applicable to the affected sources. Federal, State, local, and Tribal 
government entities would not be affected by this rule. 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 Lime Manufacturing 
source category is ``any facility engaged in producing high calcium 
lime, dolomitic lime, and dead-burned dolomite.'' However, lime 
manufacturing plants located at pulp and paper mills or at beet sugar 
factories are not included in the source category (69 FR 394, 397, 
January 5, 2004).

    Table 1--NESHAP and Industrial Source Categories Affected by This
                             Proposed Action
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       Source category and NESHAP                 NAICS code \1\
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Lime Manufacturing.....................  32741, 33111, 3314, 327125.
------------------------------------------------------------------------
\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 supplemental 
proposal at https://www.epa.gov/stationary-sources-air-pollution/lime-manufacturing-plants-national-emission-standards-hazardous. Following 
publication in the Federal Register, the EPA will post the Federal 
Register version of this supplemental proposal rule and key technical 
documents at this same website.

[[Page 9090]]

II. Background

A. What is the statutory authority for this action?

    On January 5, 2023, the EPA proposed to amend the National Emission 
Standards for Hazardous Air Pollutants for Lime Manufacturing Plants 
(Lime Manufacturing NESHAP), to set emission standards for four 
previously unregulated pollutants.\1\ This supplemental proposal seeks 
comment on revisions to the proposed emission limits for HCl, mercury, 
organic HAP, and D/F based on information received from public 
commenters and other sources of information, including the small 
business review panel.
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    \1\ 88 FR 805 (Jan. 5, 2023).
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    In Louisiana Environmental Action Network v. EPA (LEAN), 955 F.3d 
1088 (D.C. Cir. 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 source category in the 8-year 
review. To meet this obligation, the EPA issued the January 5, 2023, 
proposed rule to address unregulated emissions of HAP from the lime 
manufacturing source category. The proposed amendments defined the 
maximum achievable control technology (MACT) standard for hydrogen 
chloride (HCl), mercury, total hydrocarbon (THC) as a surrogate for 
organic HAP, and dioxin/furans (D/F) within the lime manufacturing 
source category pursuant to the Clean Air Act (CAA) sections 112(d)(2) 
and (3). This proposal supplements the January 5, 2023, proposed rule 
amendments.

B. What is this source category and how does the current NESHAP 
regulate its HAP emissions?

    The EPA promulgated the Lime Manufacturing NESHAP on January 5, 
2004 (69 FR 394). The standards are codified at 40 CFR part 63, subpart 
AAAAA. The lime manufacturing industry consists of facilities that use 
a lime kiln to produce lime product from limestone by calcination. The 
source category covered by this MACT standard currently includes 34 
facilities.
    As promulgated in 2004, the current Lime Manufacturing NESHAP 
regulates HAP emissions from all new and existing lime manufacturing 
plants that are major sources, co-located with major sources, or are 
part of major sources. A lime manufacturing plant is defined as any 
plant which uses a lime kiln to produce lime product from limestone or 
other calcareous material by calcination. The NESHAP specifically 
excludes lime kilns that use only calcium carbonate waste sludge from 
water softening processes as the feedstock. In addition, lime 
manufacturing plants located at pulp and paper mills or at beet sugar 
factories are not subject to the NESHAP. Lime manufacturing operations 
at pulp and paper mills are subject to the NESHAP for combustion 
sources at kraft, soda, and sulfite pulp and paper mills.\2\ Lime 
manufacturing operations at beet sugar processing plants are not 
subject to the Lime Manufacturing NESHAP because beet sugar lime kiln 
exhaust is typically routed through a series of gas washers to clean 
the exhaust gas prior to process use. Other lime manufacturing plants 
that are part of multiple operations, such as (but not limited to) 
those at steel mills and magnesia production facilities, are subject to 
the Lime Manufacturing NESHAP.
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    \2\ 66 FR 3180, January 12, 2001.
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    The current Lime Manufacturing NESHAP defines the affected source 
as each lime kiln and its associated cooler and each individual 
processed stone handling (PSH) operations system. The PSH operations 
system includes all equipment associated with PSH operations beginning 
at the process stone storage bin(s) or open storage pile(s) and ending 
where the process stone is fed into the kiln. It includes man-made 
process stone storage bins (but not open process stone storage piles), 
conveying system transfer points, bulk loading or unloading systems, 
screening operations, surge bins, bucket elevators, and belt conveyors.
    The current Lime Manufacturing NESHAP established particulate 
matter (PM) emission limits for lime kilns, coolers, and PSH operations 
with stacks. The NESHAP also established opacity limits for kilns 
equipped with electrostatic precipitators (ESP) and fabric filters (FF) 
and scrubber liquid flow limits for kilns equipped with wet scrubbers. 
Particulate matter serves as a surrogate for the non-mercury metal HAP. 
The NESHAP also regulates opacity or visible emissions from most of the 
PSH operations, with opacity also serving as a surrogate for HAP 
metals.
    The PM emission limit for existing kilns and coolers is 0.12 pounds 
PM per ton of stone feed (lb/tsf) for kilns using dry air pollution 
control systems (e.g., dry scrubbers, fabric filters, baghouses) prior 
to January 5, 2004. Existing kilns that have installed and are 
operating wet scrubbers prior to January 5, 2004, must meet an emission 
limit of 0.60 lb/tsf. Kilns which meet the criteria for the 0.60 lb/tsf 
emission limit must continue to use a wet scrubber for PM emission 
control in order to be eligible to meet the 0.60 lb/tsf limit. If at 
any time such a kiln switches to a dry control, it would become subject 
to the 0.12 lb/tsf emission limit, regardless of the type of control 
device used in the future. The PM emission limit for all new kilns and 
lime coolers is 0.10 lb/tsf. As a compliance option, these emission 
limits (except for the 0.60 lb/tsf limit) may be averaged across kilns 
and coolers at the lime manufacturing plant. If the lime manufacturing 
plant has both new and existing kilns and coolers, then the emission 
limit would be an average of the existing and new kiln PM emissions 
limits, weighted by the annual actual production rates of the 
individual kilns, except that no new kiln may exceed the PM emission 
level of 0.10 lb/tsf. Existing kilns that have installed and are 
operating wet scrubbers prior to January 5, 2004, and that are required 
to meet a 0.60 lb/tsf emission limit must meet that limit individually, 
and they may not be included in any averaging calculations.
    Emissions from PSH operations that are vented through a stack are 
subject to a limit of 0.05 grams PM per dry standard cubic meter (g/
dscm) and 7 percent opacity. Stack emissions from PSH operations that 
are controlled by wet scrubbers are subject to the 0.05 g PM/dscm limit 
but are not subject to the opacity limit. Fugitive emissions from PSH 
operations are subject to a 10 percent opacity limit.
    For each building enclosing any PSH operation, each of the affected 
PSH operations in the building must comply individually with the 
applicable PM and opacity emission limitations. Otherwise, there must 
be no visible emissions from the building, except from a vent, and the 
building's vent emissions must not exceed 0.05 g/dscm and 7 percent 
opacity. For each fabric filter that controls emissions from only an 
individual, enclosed processed stone storage bin, the opacity must not 
exceed 7 percent. For each set of multiple processed stone storage bins 
with combined stack emissions, emissions must not exceed 0.05 g/dscm 
and 7 percent opacity. The current Lime Manufacturing NESHAP does not 
allow averaging of PSH operations.
    The 2020 amendments finalized the residual risk and technology 
review (RTR) conducted for the Lime Manufacturing NESHAP. The 2020 RTR 
found that the Lime Manufacturing NESHAP provided an ample margin of 
safety to protect public health, more stringent standards were not 
necessary to prevent an adverse environmental effect, and that there 
were no developments in practices, processes, or control technologies 
that would warrant

[[Page 9091]]

revisions to the standards. In addition, the 2020 RTR addressed periods 
of startup, shutdown, and malfunction (SSM) by removing any exemptions 
during SSM operations. Lastly, the 2020 amendments included provisions 
requiring electronic reporting.

C. What changes did we propose for the lime manufacturing source 
category in our January 5, 2023, proposal?

    On January 5, 2023, the EPA published a proposal in the Federal 
Register for the Lime Manufacturing NESHAP, 40 CFR part 63, subpart 
AAAAA to propose setting MACT standards for HCl, mercury, THC as a 
surrogate for organic HAP, and D/F. Table 2 includes a summary of the 
MACT standards in the January 5, 2023, proposal.

             Table 2--Summary of New and Existing Source Limits for the Lime Manufacturing NESHAP Included in the January 5, 2023, Proposal
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                                                                                        New                             Existing
            Pollutant \1\                  Kiln type \2\        Stone produced \3\     source      Unit of measure       source       Unit of measure
                                                                                       limit                             limit
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HCl.................................  SR....................  DL, DB................      1.6  lb/ton stone produced.        2.2  lb/ton stone produced.
                                      SR....................  QL....................    0.021  lb/ton stone produced.       0.58  lb/ton stone produced.
                                      PR....................  DL, DB................     0.39  lb/ton stone produced.       0.39  lb/ton stone produced.
                                      PR....................  QL....................    0.015  lb/ton stone produced.      0.015  lb/ton stone produced.
                                      VK....................  QL....................    0.021  lb/ton stone produced.      0.021  lb/ton stone produced.
Mercury.............................  All...................  QL, DL................     24.9  lb/MMton stone               24.9  lb/MMton stone
                                                                                                produced.                          produced.
                                      All...................  DB....................     24.4  lb/MMton stone               33.1  lb/MMton stone
                                                                                                produced.                          produced.
THC.................................  All...................  All...................     0.86  ppmvd as propane @7          3.47  ppmvd as propane @7
                                                                                                percent O2.                        percent O2.
D/F.................................  All...................  All...................    0.028  ng/dscm (TEQ) @7            0.028  ng/dscm (TEQ) @7
                                                                                                percent O2.                        percent O2.
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\1\ Hydrogen chloride (HCl), total hydrocarbon (THC), dioxin/furans (D/F).
\2\ Straight rotary kiln (SR), preheater rotary kiln (PR), vertical kiln (VK).
\3\ Dolomitic lime (DL), quick lime (QL), dead burned dolomitic lime (DB).

III. Analytical Results and Proposed Decisions

    This section provides a description of this proposal, which 
supplements the January 5, 2023, proposed amendments, and the EPA's 
rationale for this supplemental proposal.

A. What revisions are we proposing to the hydrogen chloride emission 
standards?

    As a result of reviewing public comments received on the January 5, 
2023, proposed amendments, the EPA was made aware of five instances 
where kilns were subcategorized as preheater rotary kilns (PR) 
producing quick lime (QL) but were in fact straight rotary kilns (SR) 
producing QL. All five kilns identified are located at the Carmeuse 
Lime and Stone plant in Gary, Indiana. One of these five kilns was in 
the HCl MACT pool for the PR, QL subcategory, and was included in the 
Upper Predictive Limit (UPL) calculations. This kiln was moved from 
this subcategory to the SR, QL subcategory. Removing this kiln from the 
PR, QL subcategory and adding it to the SR, QL subcategory changed the 
data used in the UPL calculation and therefore changed the UPL 
calculation results. Refer to the memorandum ``Maximum Achievable 
Control Technology (MACT) Floor Analysis for the Lime Manufacturing 
Plants Industry Supplemental Proposal,'' which is included in the 
docket for this rulemaking, for a detailed description of the revised 
calculations.
    In addition, in the January 5, 2023, proposal we did not 
subcategorize vertical kilns by the type of stone produced. We received 
a comment that the EPA should subcategorize vertical kilns by product, 
similar to the subcategorization of rotary kilns. (See Docket ID No. 
EPA-HQ-OAR-20177-0015-0166). In this action we are proposing a vertical 
kiln (VK): dolomitic lime (DL), dead-burned, dolomitic lime (DB) 
subcategory as was done with the proposed PR, DL/DB rotary kiln 
emission limits.
    The changes in our proposed HCl emission limits for new and 
existing sources are include in table 3.

              Table 3--Summary of Re-Proposed New and Existing Source Limits for Hydrogen Chloride
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                                                                             New source limit   Existing source
               Kiln type \1\                      Stone produced \2\          (lb/ton stone      limit (lb/ton
                                                                                produced)       stone produced)
----------------------------------------------------------------------------------------------------------------
SR........................................  QL                                          0.015               0.52
SR........................................  DL, DB                                        1.7                2.3
PR........................................  QL                                          0.096              0.096
PR........................................  DL, DB                                       0.39               0.39
VK........................................  QL                                          0.021              0.021
VK........................................  DL, DB                                       0.39               0.39
----------------------------------------------------------------------------------------------------------------
\1\ Straight rotary kiln (SR), preheater rotary kiln (PR), vertical kiln (VK).
\2\ Dolomitic lime (DL), quick lime (QL), dead burned dolomitic lime (DB).

    In the January 5, 2023, proposal the EPA estimated that applying a 
removal efficiency of dry sorbent injection (DSI) controls using 
hydrated lime to each kiln in the source category to meet the MACT 
floor would result in a reduction of HCl emissions from these sources 
of 1,163 tons per year (tpy). As a result of the changes to these 
subcategories, explained in this section, the EPA now estimates that 
applying a removal efficiency of DSI controls to meet the MACT floor 
would result in a reduction of HCl emissions from these sources of 884 
tons of HCl per year.
    We conducted a revised beyond-the-floor analysis, where we 
evaluated whether existing kilns would be able to comply with the 
proposed new source HCl MACT floor limits. We found that

[[Page 9092]]

the estimated reduction in HCl emissions from existing sources 
complying with a beyond-the-floor HCl limit is 1,453 tpy. The estimated 
incremental reduction, where we compare the existing source beyond-the-
floor limit to the existing source MACT floor limit, is 568 tpy. Refer 
to the memorandum ``Maximum Achievable Control Technology (MACT) Floor 
Analysis for the Lime Manufacturing Plants Industry Supplemental 
Proposal,'' which is included in the docket for this rulemaking, for a 
detailed description of the revised calculations. Using revised cost 
calculations (refer to section IV.C. of this preamble) we estimate the 
total capital investment to be $749,000,000 and total annual costs to 
be $139,000,000 per year for beyond-the-floor limits. This results in a 
cost effectiveness of approximately $95,000 per ton of HCl removal. We 
do not consider these control costs to be reasonable compared to other 
rules where we have regulated HCl and costs were a consideration.\3\ 
Therefore we are not proposing a beyond-the-floor standard for HCl. 
Refer to the memorandum, ``Cost Impacts for the Lime Manufacturing 
Plants Industry Supplemental Proposal'', included in the docket of this 
rulemaking.
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    \3\ See 86 FR 64393, November 18,2021, where we found that 
$26,000/ton for HCl was not cost effective as a beyond-the-floor 
option.
---------------------------------------------------------------------------

    As part of our beyond-the-floor analysis, we typically identify 
control techniques that have the ability to achieve an emissions limit 
more stringent than the MACT floor. No techniques were identified that 
would achieve HAP reductions greater than the new source floors for the 
HCl subcategories. Therefore, consistent with the January 5, 2023, 
proposal the EPA is not proposing a beyond-the-floor HCl limit for new 
sources in this supplemental proposal.
    In its report, the Small Business Advocacy Review Panel requested 
that the EPA consider establishing a health-based emission limit (HBEL) 
for HCl and asked the EPA to take comment on a potential HBEL standard. 
For a HAP with an established health threshold, CAA section 112(d)(4) 
allows the EPA to consider such health thresholds when establishing 
emission standards under CAA section 112(d). Section 112(d)(4) of the 
CAA states, ``With respect to pollutants for which a health threshold 
has been established, the Administrator may consider such threshold 
level, with an ample margin of safety, when establishing emission 
standards under this subsection.'' In other words, for HAP with a 
health threshold, standards may be promulgated under a process 
different from that otherwise specified in CAA section 112(d), and 
these standards are referred to as HBEL. Based on the request, the EPA 
seeks comment on establishing an HBEL under CAA section 112(d)(4) for 
HCl.
    The EPA is mindful that, in Sierra Club v. Environmental Protection 
Agency, 895 F.3d 1 (D.C. Cir. 2018), the court remanded the NESHAP for 
Brick and Structural Clay Products Manufacturing and for Clay Ceramics 
Manufacturing. The court found that the EPA had not sufficiently 
supported its determination that HCl is a ``pollutant for which a 
health threshold has been established''; specifically, the court 
determined that the rulemaking record did not show that HCl is not a 
carcinogen. 895 F.3d at 11. The court also stated that the EPA had not 
sufficiently explained why it had used the EPA inhalation Reference 
Concentration (RfC) instead of using California's health value in 
setting the HBEL. Below, the EPA considers the court's points related 
to the denying the use of an HBEL for HCl as well as an example of how 
an HBEL may be established for this rulemaking.
    With regard to carcinogenicity, it is important to acknowledge that 
the science and methods of cancer risk assessment have evolved over the 
33 years since the CAA amendments were issued. The EPA now recognizes 
that carcinogens can be either non-threshold or threshold 
pollutants.\4\ Linear non-threshold carcinogens can cause adverse 
health effects, including cancer, at any level of exposure. In 
contrast, non-linear threshold carcinogens may pose a cancer risk only 
above a certain exposure level. Based on the science and methods 
developed over the last 33 years, and CAA section 112(d)(4)'s focus on 
a threshold, not cancer risk, we believe that the issue is not whether 
HCl is a carcinogen but rather whether HCl has a threshold.
---------------------------------------------------------------------------

    \4\ U.S. EPA. 2005. Guidelines for Carcinogen Risk Assessment. 
U.S. Environmental Protection Agency, Washington DC.
---------------------------------------------------------------------------

    An important consideration when determining if a carcinogen has a 
threshold is whether it is mutagenic. If a pollutant is mutagenic, 
science supports that any dose may cause cancer; in other words, there 
is not likely to be a threshold. In the case of HCl, the available 
evidence does not indicate that HCl has a mutagenic effect. Bacteria 
that have been exposed to HCl in research studies have not exhibited 
any mutations.\5\ Although studies reported by Morita et al. (1989) \6\ 
and Brusick (1986) \7\ involving mammalian exposure to HCl have found 
mutagenicity, researchers have concluded that these effects are an 
artifact of acidic conditions caused by exceptionally high doses of 
HCl. Genotoxic or mutagenic effects caused at high doses by changes in 
pH are not relevant to environmental levels of exposure under normal 
physiological conditions.
---------------------------------------------------------------------------

    \5\ International Agency for Research on Cancer (IARC). 1992. 
IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. 
Volume 54: Occupational Exposures to Mists and Vapours from Strong 
Inorganic Acids; and Other Industrial Chemicals. World Health 
Organization, Lyon.
    \6\ Morita T., Watanabe Y., Takeda K., Okumura K. Effects of pH 
in the in vitro chromosomal aberration test. Mutat. Res. 
1989;225:55-60.
    \7\ Brusick D. Genotoxic effects in cultured mammalian cells 
produced by low pH treatment conditions and increased ion 
concentrations. Environ. Mutag. 1986;8:879-886.
---------------------------------------------------------------------------

    Another important consideration in determining whether a pollutant 
has a threshold is understanding whether there are alternative 
mechanisms by which the observed effects could lead to the development 
of cancer. In an animal study designed to observe cancer outcomes, rats 
exposed to HCl showed increased cell production and tissue enlargement, 
known as hyperplasia, in the respiratory tract. However, the rats 
showed no evidence of HCl-induced tumors or cancer.\8\ Hyperplasia may 
or may not progress to tumor development and cancer over time.\9\ 
However, cancer cannot occur through this mechanism if exposure is 
below the threshold at which hyperplasia occurs. Continuous exposure to 
a chemical or its metabolite can cause persistent cell killing which in 
turn may result in regenerative hyperplasia in the damaged tissue. The 
EPA's Office of Pesticides recognizes that ``for irreversible tissue 
alterations to occur in humans, including cancer by this mode of 
action, a sufficient exposure (emphasis added) must be encountered over 
a prolonged period.'' \10\ The EPA's Integrated Risk Information System 
(IRIS) program has similarly recognized the existence of a threshold of 
exposure for hyperplasia and resulting cancer outcomes from exposure to 
chloroform. Chloroform was

[[Page 9093]]

labeled as likely to be carcinogenic to humans under high-exposure 
conditions that cause hyperplasia. However, the EPA concluded that 
chloroform is not likely to be carcinogenic to humans under exposure 
conditions that do not cause hyperplasia.\11\
---------------------------------------------------------------------------

    \8\ U.S. Environmental Protection Agency. Integrated Risk 
Information System (IRIS) on Hydrogen Chloride. National Center for 
Environmental Assessment, Office of Research and Development, 
Washington, DC. 1995.
    \9\ NCI Dictionary of Cancer terms. National Cancer Institute. 
(n.d.). Retrieved October 30, 2023, from https://www.cancer.gov/publications/dictionaries/cancer-terms/def/hyperplasia.
    \10\ EPA (2018) Chemicals evaluated for carcinogenic potential 
annual cancer report 2018. U.S. Environmental Protection Agency.
    \11\ U.S. Environmental Protection Agency. Integrated Risk 
Information System (IRIS) on Chloroform. National Center for 
Environmental Assessment, Office of Research and Development, 
Washington, DC. 2001.
---------------------------------------------------------------------------

    The EPA derived a reference concentration (RfC) for HCl which 
identifies a health-based threshold for hyperplasia \12\. This RfC 
represents an estimate (with uncertainty spanning perhaps an order of 
magnitude) of a daily inhalation exposure to the human population 
(including sensitive subgroups) that is likely to be without an 
appreciable risk of deleterious effects during a lifetime. An expert 
review workshop had previously evaluated the evidence available for HCl 
and for a similar chemical, sulfuric acid, and suggested that no 
adverse effects from exposure to HCl would be expected in humans at or 
below 3 mg/m3.\13\ The EPA performed an independent evaluation to 
identify a value expected to be without adverse effects, including in 
sensitive subgroups. The EPA's dose-response evaluation incorporated a 
300-fold factor to account for any residual uncertainty, including the 
potential for variability in response across the human population. The 
final RfC derived by the EPA was 0.02 mg/m3.\14\ Exposure to HCl in the 
general population is expected to occur below 3 mg/m3 and 0.02 mg/m3, 
below which there are no observable adverse health effects. Considering 
the evidence regarding \15\ and the availability of a hyperplasia 
protective health threshold, the EPA seeks comment on whether it is 
appropriate to consider HCl a threshold pollutant under CAA section 
112(d)(4). The EPA also requests comments on new or additional 
scientific evidence that will inform the agency whether or not HCl has 
a threshold.
---------------------------------------------------------------------------

    \12\ U.S. Environmental Protection Agency. Integrated Risk 
Information System (IRIS) on Hydrogen Chloride. National Center for 
Environmental Assessment, Office of Research and Development, 
Washington, DC. 1995.
    \13\ Kamrin, M.A. 1992. Workshop on the health effects of HCl in 
ambient air. Reg. Pharm. Toxicol.15: 73-82.
    \14\ Environmental Protection Agency. Integrated Risk 
Information System (IRIS) on Hydrogen Chloride. National Center for 
Environmental Assessment, Office of Research and Development, 
Washington, DC. 1995.
    \15\ HCl concentrations in the ambient air usually do not exceed 
0.01 mg/m3 (IARC, 1992).
---------------------------------------------------------------------------

    In its 2018 opinion in Sierra Club, the D.C. Circuit also stated 
that the EPA did not fully explain why the EPA's RfC for HCl, which the 
Agency has designated as a ``low confidence'' value, was preferable to 
an alternative value developed by the California EPA, known as the 
chronic reference exposure level (REL). The EPA had previously 
explained in its Methods for Derivation of Inhalation Reference 
Concentrations and Application of Inhalation Dosimetry and Guidelines 
for Carcinogenic Risk Assessment that the Agency derives RfC only when 
there are enough data to designate a pollutant as having a threshold 
and there are enough data to set a numerical RfC. Also, after deriving 
an RfC, the EPA evaluates the data used to derive the RfC and assigns 
confidence levels of high, medium, or low to each of its reference 
concentrations based on the completeness of the supporting data 
base.\16\ A ``low confidence'' label in the RfC is applied to a 
derivation that is based on several data extrapolations and a less 
complete data base than those with a ``high confidence'' or ``medium 
confidence'' labels. Therefore, a ``low confidence'' RfC value 
indicates that it may change if additional supporting data become 
available. It does not mean that the current available data base is 
weak or unreliable. In fact, the principal and supporting studies 
selected to derive the RfC for HCl meet the data base criteria for 
estimation of an RfC which means that the data base is adequate and 
acceptable. The California EPA chronic REL for HCl was derived using 
the same principal and supporting studies. Therefore, the California 
EPA value reflects the same data base confidence as the EPA RfC.
---------------------------------------------------------------------------

    \16\ U.S. EPA, 1994. Methods for Derivation of Inhalation 
Reference Concentrations and Application of Inhalation Dosimetry 
[See section 4.3.9.2. Assignment of Confidence Levels, p. 4-80-82].
---------------------------------------------------------------------------

    While the EPA and California EPA values were derived using the same 
principal study and similar methodologies, there was a significant 
difference in the derivation of each value, which led to the California 
EPA value being more stringent. The principal driver for this 
difference was the California EPA's exclusion of mid-respiratory tract 
(i.e., trachea) effects from its dosimetry adjustment calculations.\17\ 
By contrast, the EPA incorporated both upper- (i.e., nose, mouth) and 
mid-respiratory tract effects. California EPA's sole rationale for the 
exclusion of mid-respiratory tract effects was based on the prediction 
that humans are expected to be relatively more susceptible in the 
upper-respiratory tract.
---------------------------------------------------------------------------

    \17\ OEHHA. (2000). Determination of Noncancer Chronic Reference 
Exposure Levels. Appendix D.3 Chronic RELs and toxicity summaries 
using the previous version of the Hot Spots Risk Assessment 
guidelines (OEHHA 1999). Chronic Toxicity Summary: Hydrogen 
Chloride.
---------------------------------------------------------------------------

    Although the predominant effects of inhaled HCl are expected to 
occur in the upper respiratory tract, the EPA disagrees with the 
California EPA's exclusion of mid-respiratory tract effects and 
believes that California EPA's approach is inconsistent with the EPA's 
own guidelines for deriving inhalation reference concentrations. The 
principal study relied upon by the EPA and California EPA reported that 
rats exposed to HCl developed a higher incidence of hyperplasia in both 
upper- and mid-respiratory tracts. Furthermore, the EPA guidelines 
establish that when effects are observed in the mid-respiratory tract, 
this region should also be considered in the dosimetry adjustment 
calculations.\18\ Therefore, the EPA approach to derive the RfC is more 
robust because it better represents the observed respiratory effects 
reported in the scientific literature.
---------------------------------------------------------------------------

    \18\ U.S. EPA, 2009. STATUS REPORT: Advances in Inhalation 
Dosimetry of Gases and Vapors with Portal of Entry Effects in the 
Upper Respiratory Tract. U.S. Environmental Protection Agency, 
Washington, DC.
---------------------------------------------------------------------------

    In contemplating whether the EPA could set an HBEL for HCl 
emissions in the lime manufacturing source category, the EPA reviewed 
the conclusions on the potential for HCl to cause adverse health 
effects in the 2020 RTR. The maximum chronic Hazard Quotient (HQ) for 
HCl was 0.04, and the maximum acute HQ hazard was 0.6 based upon actual 
emissions. Because the hazards associated with HCl were acceptable with 
an ample margin of safety in the 2020 RTR, it is possible to 
contemplate setting an HBEL for this rule. Refer to the November 2023 
memorandum ``Risk Approach to Assess a Health-Based Emission Limit for 
Hydrochloric Acid for the Lime Manufacturing Source Category,'' located 
in the docket for this rulemaking. The modeling methodology applied for 
both the 2020 RTR and the 2023 HBEL proposal accounts for aggregate 
impacts to census blocks for locations that may have multiple lime 
manufacturing plants within a 50 km domain. The proposed HBEL for HCl 
is at an emission level that is higher than the modeled actual 
emissions for the 2020 RTR. An example of what an HBEL for HCl might 
look like is presented below.
    To set an HBEL for HCl, we would establish an emission standard to 
ensure that levels of HCl remain well below the concentrations at which 
any impacts would be expected to occur. As an example, an appropriate 
approach to

[[Page 9094]]

setting a health-based threshold might be to establish a mass-based 
standard. Such a standard could include both a tons per year limit as 
well as a pounds per hour limit to ensure protection from both chronic 
and acute impacts. We have provided an analysis of such a standard in 
the November 2023 memorandum ``Risk Approach to Assess a Health-Based 
Emission Limit for Hydrochloric Acid for the Lime Manufacturing Source 
Category,'' located in the docket for this rulemaking. Based on this 
analysis, the HBEL would be an emission limit of 300 tpy, not to exceed 
685 pounds per hour (lb/hr). We would expect such a limit to ensure 
that HCl emissions from this source category, while could be higher 
than in the proposal would remain at levels consistent with a chronic 
HQ no greater than 0.2 and a maximum acute HQ no greater than 0.6. We 
request comment on whether such a standard would provide an ample 
margin of safety and whether additional measures would be needed to do 
so.
    Appropriate monitoring, recordkeeping, and reporting requirements 
would also be required to ensure compliance with the limit. The EPA is 
requesting comment on an appropriate structure for incorporating an 
HBEL in the rule text. Refer to the memorandum, ``Revisions to 40 CFR 
part 63 Subpart AAAAA to Accommodate a Health-Based Standard'', 
included in the docket for this rulemaking, for a description of 
potential revisions to the subpart to include initial compliance, 
continuous compliance, recordkeeping, and reporting rule language in 
support of an HBEL.

B. What revisions are we proposing to the mercury emission standards?

    Prior to the January 5, 2023, proposed rule, the EPA evaluated the 
use of an intra-quarry variability (IQV) factor to be applied in the 
mercury UPL calculations to account for the naturally occurring 
variability in mercury content of the raw materials. The formation of 
the rock being mined for raw materials occurred over a large span of 
geological time. Consistent with the approach followed in the Portland 
Cement Manufacturing NESHAP, 40 CFR part 63, subpart LLL, and the Brick 
and Structural Clay Products NESHAP, 40 CFR part 63, subpart JJJJJ, the 
IQV factor accounts for this variability in the mercury content of the 
raw material over geological time. However, in the January 5, 2023, 
proposed rule amendments we did not believe we had sufficient data to 
apply an IQV factor.
    As described in the January 5, 2023, proposal, the EPA was provided 
data from the quarries of two separate lime manufacturing facilities 
(Carmeuse Maysville and Graymont Eden quarries). Both facilities were 
included in the mercury MACT floor calculations. At the first facility, 
the mercury content of the kiln feed was sampled, and the results 
tabulated. At the second facility the quarry was sampled, at multiple 
bore-hole depths, as well as the kiln feed, and the results tabulated.
    When developing the January 5, 2023, proposal, the EPA had believed 
that the kiln feed data was more representative of the mercury content 
of the raw material, but wrongly assumed this was due to the mined 
quarry stone first being stored in open storage piles over time, where 
new stone added to the storage pile was assumed to homogenize with 
other stone in the storage pile. In the public comments received, 
industry representatives explained that stone from the quarry is stored 
in ``short-term'' storage piles,\19\ where new stone added does not 
have time to ``homogenize'' with other stone before being fed into the 
kiln. It was also noted that quarry samples, as collected in the 
Graymont bore-hole sample data, represent the intent of the IQV by 
reporting on the measured variability of the mercury content of the 
rock over varying depths, representing variations over geologic time. 
Based on these comments, the EPA reconsidered the suitability of these 
data to develop an IQV factor.
---------------------------------------------------------------------------

    \19\ Docket ID No. EPA-HQ-OAR-2017-0015-0166, section X. A.
---------------------------------------------------------------------------

    The EPA considered both the Graymont and Carmeuse quarry data in 
the IQV factor analysis. Both facilities were part of the MACT floor 
pool in the QL subcategory. From this analysis a relative standard 
deviation (RSD) was calculated by dividing the standard deviation by 
the data average. The RSD was then incorporated into the UPL 
calculations for new and existing QL sources as part of the ``pooled 
variance'' factor of the UPL equation. Refer to the memorandum 
``Maximum Achievable Control Technology (MACT) Floor Analysis for the 
Lime Manufacturing Plants Industry Supplemental Proposal,'' which is 
included in the docket for this rulemaking, for a detailed description 
of the revised calculations. The application of an IQV factor revised 
the originally proposed mercury emission limit for new and existing QL 
sources from 24.9 pounds per million tons of lime produced (rounded to 
25 lb/MMton) for both new and existing sources to 27 lb/MMton for new 
sources, and 34 lb/MMton for existing sources in the QL subcategory.
    As part of the evaluation of a mercury standard with the inclusion 
of an IQV factor, the EPA reconsidered whether a separate subcategory 
was necessary for kilns producing dead-burned dolomitic lime (DB), as 
proposed in the January 5, 2023, proposed amendments. To do this, we 
first developed standards based on no subcategorization and the 
application of an IQV factor. The result of this analysis was 27 lb Hg/
MMton for new sources and 34 lb Hg/MMton for existing sources. These 
standards were developed based on the kilns that made up the MACT pool. 
These kilns were producing high calcium quick lime (QL) and dolomitic 
lime (DL). Based on test data available, the EPA determined that kilns 
producing DB would be able to comply with this existing source standard 
after the application of air pollution controls. Based on the test data 
available, the EPA determined that there was little difference in 
mercury emissions from SR and PR kilns producing Ql and/or DL. 
Moreover, we have found that residence time of raw materials in a kiln 
has little impact on mercury emissions. We are proposing to not create 
subcategories based on kiln type in setting mercury emission limits.
    Our proposed mercury emission limits for new and existing sources, 
without subcategories, are included in table 4.

                   Table 4--Summary of Re-Proposed New and Existing Source Limits for Mercury
----------------------------------------------------------------------------------------------------------------
                                                                           New source limit     Existing source
                 Kiln type                         Stone produced           (lb/MMton stone     limit (lb/MMton
                                                                               produced)        stone produced)
----------------------------------------------------------------------------------------------------------------
All.......................................  All.........................                 27                  34
----------------------------------------------------------------------------------------------------------------


[[Page 9095]]

    In the January 5, 2023, proposed amendments the EPA estimated that 
applying a removal efficiency of activated carbon injection (ACI) 
controls to the source category to meet the MACT floor would result in 
a reduction of mercury emissions from these sources of approximately 
489 pounds of mercury per year. As a result of this supplemental 
proposal, and the inclusion of an IQV factor in the UPL calculations 
for mercury, the EPA estimates that applying ACI controls would result 
in a reduction of mercury emissions from these sources of 460 pounds of 
mercury per year.
    We conducted a beyond-the-floor analysis, where we evaluated 
whether existing kilns would be able to comply with the new source 
mercury MACT floor limits. We found that the estimated reduction in 
mercury emissions from a beyond-the-floor mercury limit is 
approximately 490 pounds (0.24 tons) of mercury per year. The estimated 
incremental reduction, where we compare the existing source beyond-the-
floor limit to the existing source MACT floor limit, is 30 pounds (0.01 
tons) of mercury per year. We estimate the total capital investment to 
be $244,000,000 and total annual costs to be $116,000,000 per year for 
beyond-the-floor limits. This results in a cost effectiveness of 
approximately $238,000 per pound ($476,000,000 per ton) of mercury 
removal. We do not consider the control costs to be reasonable compared 
to other rules where we have regulated mercury and costs are 
consideration.\20\ Therefore we are not proposing a beyond-the-floor 
standard for mercury. This is a change from that in the January 5, 
2023, proposal. Refer to the memorandum, ``Cost Impacts for the Lime 
Manufacturing Plants Industry Supplemental Proposal'', included in the 
docket of this rulemaking.
---------------------------------------------------------------------------

    \20\ See 79 FR 75638, December 18, 2014, where the EPA found 
that a beyond-the-floor option for mercury of $74,000/lb was not 
cost effective.
---------------------------------------------------------------------------

    As part of our beyond-the-floor analysis, we typically identify 
control techniques that have the ability to achieve an emissions limit 
more stringent than the MACT floor. No techniques were identified that 
would achieve HAP reductions greater than the new source floors for the 
mercury. Therefore, consistent with the January 5, 2023, proposal, the 
EPA is not proposing a beyond-the-floor mercury limit for new sources 
in this proposed rule. A detailed description of our beyond-the-floor 
analysis and conclusions is provided in the memorandum, ``Maximum 
Achievable Control Technology (MACT) Floor Analysis for the Lime 
Manufacturing Plants Industry Supplemental Proposal'' which is included 
in the docket for this rulemaking.

C. What revisions are we proposing to the organic HAP emission 
standards?

    The EPA received comments on the January 5, 2023, proposed 
amendments opposing the use of THC as a surrogate for organic HAP. 
Commenters representing industry noted that vertical kilns have 
relatively elevated THC emissions, while organic HAP emissions are 
relatively low. They note that this is because of the influence of 
unburned fuel in the kiln exhaust either due to countercurrent flow 
switching directions in twin-shaft vertical kilns, or incomplete air-
fuel mixing in single-shaft vertical kilns.
    The EPA re-evaluated the test data of organic HAP emissions and 
identified eight pollutants from the data that were found to be 
consistently emitted by the lime manufacturing source category. The 
list includes both ``high volume'' and ``low volume'' organic HAP. 
These include the following pollutants: formaldehyde, acetaldehyde, 
toluene, benzene, xylenes (a mixture of m, o, and p isomers), styrene, 
ethyl benzene, and naphthalene. The EPA has determined that the 
emissions data of these eight pollutants best represent the typical 
organic HAP emissions of the source category. Furthermore, the EPA has 
determined that controlling the emissions of these eight pollutants 
from a lime manufacturing facility by use of activated carbon or other 
means would also control potential emissions of all other organic HAP 
because the same controls applied to control the eight pollutants would 
also be effective controls for all organic HAP. For these reasons, the 
EPA is re-proposing to use an aggregated emission standard of the eight 
organic HAP identified in the data analysis as a surrogate for total 
organic HAP instead of the previously proposed THC standard. Commenters 
requested that the EPA consider a list of 13 pollutants but further 
review of the data for which the EPA could validate test reports showed 
that only the eight pollutants listed in this section were found to be 
emitted consistently.
    For each of the eight organic HAP, the EPA calculated the emission 
limit value equivalent to three times the representative detection 
level (3xRDL) of the test method. This was then compared to UPL 
calculations for the eight pollutants. In all cases for both new and 
existing sources the 3xRDL value, which represents the lowest value 
that can be accurately measured, was above the calculated UPL. We are 
accordingly proposing to set the MACT floor at this level. Refer to the 
memorandum titled, ``Maximum Achievable Control Technology (MACT) Floor 
Analysis for the Lime Manufacturing Plants Industry Supplemental 
Proposal'' included in the docket of this rulemaking for a detailed 
description of the methodology used. Table 5 includes a summary of the 
3xRDL values for each organic HAP used to develop the aggregated limit.

    Table 5--Summary of 3xRDL Values for New and Existing Organic HAP
------------------------------------------------------------------------
                                          RDL (ppmvd @ 7  3xRDL (ppmvd @
                Pollutant                   percent O2)    7 percent O2)
 
------------------------------------------------------------------------
Formaldehyde............................            0.14            0.42
Acetaldehyde............................            0.29            0.87
Toluene.................................           0.014           0.028
Benzene.................................           0.022           0.066
Xylenes (mixture of m, o, and p isomers)           0.023           0.069
Styrene.................................          0.0043           0.013
Ethyl benzene...........................           0.057            0.18
Napthalene..............................          0.0081           0.025
                                         -------------------------------
    Total...............................  ..............             1.7
------------------------------------------------------------------------


[[Page 9096]]

    Similar to the organic HAP limit in the Portland Cement NESHAP, the 
EPA is proposing to set the new and existing source organic HAP limit 
as a sum of the 3xRDL emission limit values for the eight pollutants 
identified in table 5 (1.7 ppmvd at 7 percent O2) as a 
surrogate for total organic HAP. The EPA believes that by controlling 
the emissions of the eight organic HAP identified in table 5 a source 
would also control the emissions of any organic HAP potentially emitted 
by the source. Refer to the memorandum ``Maximum Achievable Control 
Technology (MACT) Floor Analysis for the Lime Manufacturing Plants 
Industry Supplemental Proposal,'' which is included in the docket for 
this rulemaking, for a detailed description of the revised calculations 
and analyses.
    In the January 5, 2023, proposed amendments the EPA proposed a THC 
emission limit for new and existing sources and estimated that applying 
ACI controls to the source category to meet the MACT floor would result 
in a reduction of THC emissions by 566 tons of THC per year from these 
sources. With the revised proposed limits, the EPA estimates the new 
and existing source organic HAP limit would result in a reduction of 
organic HAP emissions by 20 tons of organic HAP per year.
    We conducted a beyond-the-floor analysis and found that because we 
are proposing emission limits for both new and existing sources that 
are set at 3xRDL of the test method, which is defined as the lowest 
level where a test method performs with acceptable precision, even if 
controls were available that had better performance, such performance 
could not be accurately measured. Therefore, we are not proposing a 
beyond-the-floor standard for organic HAP for new or existing sources.

D. What revisions are we proposing to the dioxin/furan emission 
standards?

    In the January 5, 2023, proposed amendments, the EPA followed the 
guidance of the June 5, 2014, memorandum titled, ``Determination of 
`non-detect' from EPA Method 29 (multi-metals) and EPA Method 23 
(dioxin/furan) test data when evaluating the setting of MACT floors 
versus establishing work practice standards'' (Docket ID No. EPA-HQ-
OAR-2017-0015-0117), which provides guidance on using detection limits 
as an indicator of the measurable presence of a given pollutant, 
specifically where multi-component samples, such as with D/F congeners, 
are the pollutants of concern. Additionally, the EPA used the 
procedures laid out in the December 13, 2011, memorandum titled ``Data 
and procedure for handling below detection level data in analyzing 
various pollutant emissions databases for MACT and RTR emissions 
limits'' (Docket ID No. EPA-HQ-OAR-2017-0015-0119), which describes the 
procedure for handling below detection level (BDL) data and developing 
RDL data when setting MACT emission limits. Similar to organic HAP, and 
in accordance with these guidance documents, the new and existing UPL 
for D/F were compared to the emission limit value determined to be 
equivalent to 3xRDL of the test method, and the 3xRDL value was found 
to be greater than the UPL. Therefore, the MACT floor limit for D/F was 
set based on the 3xRDL value of the test method.
    Commenters on the January 5, 2023, proposed amendments noted that 
in setting the 3xRDL value, the EPA set the value based on a sample 
collection volume of 4 dry standard cubic meters (dscm). Commenters 
stated that the EPA should have set the 3xRDL value based on a 3 dscm 
sample collection volume. After further review of the tables in the two 
guidance memoranda, the EPA agrees that the 3xRDL value should be based 
on a 3 dscm sample volume. In this action we are correcting the 3xRDL 
value for new and existing sources based on 3 dscm of sample collection 
volume as indicated in table 6.

                                    Table 6--Summary of Re-Proposed New and Existing Source Limits for Dioxin/Furans
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      New source                               Existing source
               Kiln type                      Stone produced            limit            Unit of measure            limit            Unit of measure
--------------------------------------------------------------------------------------------------------------------------------------------------------
All...................................  All......................           0.037   ng/dscm (TEQ) @ 7 percent           0.037   ng/dscm (TEQ) @ 7
                                                                                     O2.                                         percent O2.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Applying the limits listed above, the EPA estimates the new and 
existing source D/F MACT floor limit would result in a reduction of D/F 
emissions by 9.5 x 10-5 pounds per year (4.7 x 
10-8 tons per year).
    Similar to the organic HAP limits, we are proposing D/F emission 
limits for both new and existing sources that are set at 3xRDL of the 
test method. Because the emission limits could not be set any lower 
than 3xRDL we did not identify beyond-the-floor options and are 
proposing MACT floor-based D/F standards for new and existing sources.
    The EPA also considered whether it would be appropriate to set a 
work practice standard for D/F emissions in lieu of a numeric limit. 
Section 112(h) allows the EPA to set a work practice standard when it 
is not feasible to prescribe or enforce an emission standard. In this 
case the provision that could apply would be the application of 
measurement methodology to a particular class of sources is not 
practicable due to technological and economic limitations. This 
situation could occur if a significant majority, but not all, of the 
emissions data were below the detection limit.
    The data for D/F emissions available to the EPA consisted of three 
tests with three test runs each and five tests where there was only a 
single test run. Given that the EPA does not consider single-run 
emission tests to be valid tests for establishing MACT standards, we 
focused on the three-run emission tests. Two of these three-run tests 
detected D/F emissions. We note that none of the single-run tests 
detected D/F emissions, but overall, the EPA is proposing that the data 
do not support establishing a work practice standard because they do 
not support a finding that the application of measurement methodology 
is impracticable.
    As a result, we have determined to propose a numeric limit for D/F 
emissions. However, given the significant number of non-detect emission 
results, we are specifically requesting comment on the appropriateness 
of a work practice standard for D/F as well as any additional data that 
could support such a finding. Commenters supporting a work practice 
standard should describe how the standard would work, provide 
supporting data to demonstrate the work practice will control D/F 
emissions, and address the issue of the limited D/F emission test data 
available to the EPA.

[[Page 9097]]

E. What other actions are we proposing, and what is the rationale for 
those actions?

    The EPA is including definitions of the terms ``new source'' and 
``existing source'' as related to the requirements of this supplemental 
proposal and to clearly indicate that a ``new source'' in reference to 
the requirements of this supplemental proposal is any applicable source 
constructed after January 5, 2023, and an ``existing source'' in 
reference to the requirements of this supplemental proposal is any 
applicable source constructed before January 5, 2023.
    Additionally, the EPA is providing a definition of the term ``stone 
produced'' used in the units of measure for HCl and mercury emission 
limits. The limits are in units of mass of pollutant per mass of 
production, or pounds per ton of stone produced, where ``stone 
produced'' refers to the production of lime (QL, DL, and/or DB).

F. What revisions are we proposing to the performance testing, 
monitoring, and recordkeeping and reporting requirements?

    We are proposing an emissions averaging compliance alternative that 
would allow lime manufacturing facilities to demonstrate compliance 
with the HCl and mercury standards by averaging emissions of each 
pollutant across existing kilns located at the same facility. Under the 
emissions averaging compliance alternative, a facility with more than 
one existing kiln may average emissions across the kilns located at the 
facility provided that the emissions averaged do not exceed the limits 
included in table 7.

                                         Table 7--Emissions Averaging Compliance Alternative for HCL and Mercury
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                           Emissions
                                                                                           averaging
            Pollutant \1\                  Kiln type \2\          Stone produced \3\      alternative                    Unit of measure
                                                                                             limit
--------------------------------------------------------------------------------------------------------------------------------------------------------
HCl.................................  SR.....................  DL, DB.................             2.1  lb/ton stone produced.
                                      SR.....................  QL.....................            0.47  lb/ton stone produced.
                                      PR.....................  DL, DB.................            0.36  lb/ton stone produced.
                                      PR.....................  QL.....................           0.087  lb/ton stone produced.
                                      VK.....................  DL, DB.................            0.36  lb/ton stone produced.
                                      VK.....................  QL.....................           0.019  lb/ton stone produced.
Mercury.............................  All....................  All....................              31  lb/MMton stone produced.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Hydrogen chloride (HCl), total hydrocarbon (THC), dioxin/furans (D/F).
\2\ Straight rotary kiln (SR), preheater rotary kiln (PR), vertical kiln (VK).
\3\ Dolomitic lime (DL), quick lime (QL), dead burned dolomitic lime (DB).

    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 reductions of HCL and mercury greater than those 
achieved by application of the MACT floor on a unit-by-unit basis.
    We are proposing the emissions averaging compliance alternative for 
existing sources because we expect that it will result in a greater 
level of emissions reduction than the unit-by-unit MACT floor limits at 
a lower cost per pound of pollutant removed, while also providing 
compliance flexibility. The proposed emissions averaging compliance 
alternative is available only to existing kilns in the same subcategory 
at lime manufacturing facilities. New or reconstructed sources would be 
subject to the unit-by-unit MACT floor standards and would be required 
to comply with those standards on a unit-by-unit basis.
    This proposed emissions averaging program would have restrictions. 
First, emissions averaging would not be allowed between HCL and mercury 
emissions. Second, emissions averaging would only be permissible among 
individual existing affected units at a single lime manufacturing 
plant. Third, emissions averaging would only be permitted among kilns 
in the same subcategory. Lastly, new affected sources could not use 
emissions averaging for compliance purposes. Accordingly, we believe 
that this proposed emissions averaging program is consistent with the 
CAA.
    Emissions averaging also addresses those emission sources 
exhausting to a common stack. In a ``common stack'' scenario, a group 
of two or more existing units in the same subcategory that does not 
receive emissions from units in other subcategories or categories, a 
facility would treat such averaging group as a single existing unit for 
purposes of compliance with the requirements of the rule.
    We are also proposing to require each facility intending to use 
this emissions averaging program to develop a emissions averaging plan 
that identifies: (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 measuring the HAP being 
averaged; and (6) the operating parameters to be monitored for each 
control device.
    We are proposing an emissions averaging compliance alternative 
because we expect that it will provide a more flexible and less costly 
alternative to controlling HCL and mercury emissions from the source 
category, and we expect it will result in greater annual reductions of 
HCL and 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 lime manufacturing 
facilities. 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 that the 10 percent adjustment factor will ensure that the total 
quantity of HCl and mercury emitted from a facility's kiln exhaust will 
not exceed the facility's aggregate HCl emissions if its kilns 
individually complied with the unit-by-unit MACT floor standards. We 
expect that the practical outcome of emissions averaging will be 
emissions reductions equivalent to, or greater than, reductions 
achieved through

[[Page 9098]]

compliance with the MACT floor limits for each discrete kiln on a unit-
by-unit basis. Therefore, we expect that our proposed emissions 
averaging approach will result in the maximum achievable emissions 
reduction as required by statute. We request comment on allowing 
sources to comply with the HCL and 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.

G. What revisions to the compliance dates are we proposing?

    Amendments to the Lime Manufacturing NESHAP proposed in this 
rulemaking for adoption under CAA section 112(d)(2) and (3) 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.\21\ To establish a compliance period 
consistent with the statute, we consider the amount of time needed to 
plan and construct projects and change operating procedures. As 
provided in CAA section 112(i), all new affected sources would comply 
with these provisions by the effective date of the final amendments to 
the Lime Manufacturing NESHAP 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).
---------------------------------------------------------------------------

    \21\ 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)).
---------------------------------------------------------------------------

    The EPA projects that many existing sources would need to install 
add-on controls to comply with the proposed limits. These sources would 
require time to construct, conduct performance testing, and implement 
monitoring to comply with the revised provisions. Therefore, we are 
proposing to allow 3 years from the effective date of the amendments to 
the NESHAP for existing lime manufacturing sources to come into 
compliance.
    For all affected sources that commence construction or 
reconstruction on or before January 5, 2023, we are proposing to 
require compliance with the proposed standards within 3 years after the 
effective date of the final rule (or upon startup, whichever is later). 
For all affected sources that commenced construction or reconstruction 
after January 5, 2023, we are proposing that owners or operators comply 
with the provisions by the effective date of the final rule (or upon 
startup, whichever is later).

IV. Summary of Cost, Environmental, and Economic Impacts and Additional 
Analyses Conducted

A. What are the affected sources?

    Currently, 34 major sources subject to the Lime Manufacturing 
NESHAP are operating in the United States. An affected source under the 
NESHAP is the owner or operator of a lime manufacturing plant that is a 
major source, or that is located at, or is a part of, a major source of 
HAP emissions, unless the lime manufacturing plant is located at a 
kraft pulp mill, soda pulp mill, sulfite pulp mill, beet sugar 
manufacturing plant, or only processes sludge containing calcium 
carbonate from water softening processes. A lime manufacturing plant is 
an establishment engaged in the manufacture of lime products (calcium 
oxide, calcium oxide with magnesium oxide, or dead burned dolomite) by 
calcination of limestone, dolomite, shells, or other calcareous 
substances. 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.
    The Lime Manufacturing NESHAP applies to each existing or new lime 
kiln and their associated cooler(s). In addition, the NESHAP applies to 
each PSH operation located at the plant. This includes storage bins, 
conveying systems and transfer points, bulk loading and unloading 
operations, screening operations, surge bins, and bucket elevators.

B. What are the air quality impacts?

    As with the January 5, 2023, proposed rule, this action proposes 
standards for HCl, mercury, organic HAP, and D/F that will limit 
emissions and require, in some cases, the installation of additional 
controls at lime manufacturing plants at major sources. Compliance with 
the emission standards set in this proposed rule will result in a 
combined reduction of total HAP of 905 tons of HAP per year. 
Specifically, installation of controls will reduce HCl emissions by 884 
tpy. The installation of controls will reduce mercury emissions by 457 
lbs per year (0.23 tpy). The installation of controls will reduce 
organic HAP emissions by 20 tpy. Finally, the installation of controls 
will reduce D/F emissions by 9.5x10-5 lbs per year 
(4.7x10-8 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 ``Lime Impacts Memorandum,'' in the docket for a 
detailed discussion of the analyses performed on potential secondary 
impacts. (Docket ID No. EPA-HQ-OAR-2017-0015).

C. What are the cost impacts?

    This action proposes emission limits for new and existing sources 
in the lime manufacturing source category. Although the 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 
annualized cost of the proposed rule to existing sources in the lime 
manufacturing source category to be $174,000,000 per year. The annual 
costs are expected to be based on operation and maintenance of the 
added control systems. A memorandum titled ``Maximum Achievable Control 
Technology (MACT) Floor Analysis for the Lime Manufacturing Plants 
Industry Supplemental Proposal'' includes details of our cost 
assessment and is included in the docket for this rulemaking (Docket ID 
No. EPA-HQ-OAR-2017-0015).

D. What are the economic impacts?

    For the proposed rule, the EPA estimated the cost of installing 
additional air pollution control devices in order to comply with the 
proposed emission limits. This includes both the capital costs of the 
initial installation and subsequent operation and maintenance costs. 
The assumed equipment life of the recommended controls for this NESHAP 
is twenty years. 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 rule, the expected annual cost 
is $5,200,0000 (on average) for each facility, with an estimated 
nationwide annual cost of $174,000,000

[[Page 9099]]

per year. The 34 affected facilities are owned by 11 parent companies, 
and the total costs associated with the proposed amendments are 
expected to be greater than 1 percent of annual sales revenue per 
ultimate owner.
    The EPA also prepared a small business screening assessment to 
determine if any of the identified affected entities are small 
entities, as defined by the U.S. Small Business Administration. This 
analysis is available in the docket for this rulemaking. Because the 
total costs associated with the proposed amendments are expected to be 
greater than 1 percent of annual sales revenue per owner in the lime 
manufacturing source category, there are economic impacts from these 
proposed amendments on the three affected facilities that are owned by 
small entities. Refer to section VII.C. of this preamble for a detailed 
description of the small business outreach and regulatory flexibility 
analysis performed in conjunction with this proposed rule.
    The EPA predicts that the affected sources in the lime 
manufacturing source category will be able to fully pass on their 
compliance costs to their customers. International trade of lime 
products is quite limited and there are no readily available cost-
competitive substitutes for lime. Therefore, affected sources are not 
likely to face competition from foreign lime producers or from 
substitutes for their product.
    Information on our cost impact estimates on the sources in the lime 
manufacturing source category is available in the document titled, 
``Regulatory Impact Analysis for the Supplemental Proposed Amendments 
to the National Emission Standards for Hazardous Air Pollutants: Lime 
Manufacturing Plants,'' which is included in the docket for this 
rulemaking.

E. What are the benefits?

    The EPA did not monetize the benefits from the estimated emission 
reductions of HAP associated with this final action. The EPA currently 
does not have sufficient methods to monetize benefits associated with 
HAP, HAP reductions, and risk reductions for this rulemaking. However, 
we estimate that the final rule amendments would reduce emissions by 
905 tons per year and thus lower risk of adverse health effects in 
communities near lime manufacturing plants.

F. What analysis of environmental justice did we conduct?

    The results of the demographic analysis performed alongside the 
January 5, 2023, proposed amendments remain unchanged as a result of 
this supplemental proposal. For convenience, the demographic analysis 
is repeated in this preamble for the public's information.
    The EPA defines environmental justice (EJ) as ``the just treatment 
and meaningful involvement of all people regardless of income, race, 
color, national origin, Tribal affiliation, or disability, in agency 
decision-making and other Federal activities that affect human health 
and the environment so that people (i) are fully protected from 
disproportionate and adverse human health and environmental effects 
(including risk) and hazards, including those related to climate 
change, the cumulative impacts of environmental and other burdens, and 
the legacy of racism or other structural or systemic barriers; and (ii) 
have equitable access to a healthy, sustainable, and resilient 
environment in which to live, play, work, grow, worship, and engage in 
cultural and subsistence practices''.\22\ In recognizing that 
particular communities often bear an unequal burden of environmental 
harms and risks, the EPA continues to consider ways of to advance 
environmental justice and of protecting communities with from 
disproportionate adverse public health and environmental effects of air 
pollution.
---------------------------------------------------------------------------

    \22\ https://www.federalregister.gov/documents/2023/04/26/2023-08955/revitalizing-our-nations-commitment-to-environmental-justice-for-all.
---------------------------------------------------------------------------

    To examine the potential for any EJ issues that might be associated 
with lime manufacturing facilities, we performed a proximity 
demographic analysis, which is an assessment of individual demographic 
groups of the populations living within 5 km (~3.1 miles) and 50 km 
(~31 miles) of the facilities. The EPA then compared the data from this 
analysis to the national average for each of the demographic groups. In 
this preamble, we focus on the proximity results for the populations 
living within 5 km (~3.1 miles) of the facilities. The results of this 
proximity analysis for populations living within 50 km are included in 
the document titled ``Analysis of Demographic Factors for Populations 
Living Near Lime Manufacturing Facilities'', which is available in the 
docket for this action.
    The results (see table 8) show that for populations within 5 km of 
the 34 Lime Manufacturing facilities, the following demographic groups 
were above the national average: Hispanic/Latino (37 percent versus 19 
percent nationally), linguistically isolated households 21 percent 
versus 5 percent nationally), people living below the poverty level (27 
percent versus 13 percent nationally), people of color (50 percent 
versus 40 percent nationally, and people without a high school diploma 
(17 percent versus 12 percent nationally). A summary of the proximity 
demographic assessment performed for the major source lime 
manufacturing facilities is included as table 8. The methodology and 
the results of the demographic analysis are presented in a technical 
report, Analysis of Demographic Factors for Populations Living Near 
Lime Manufacturing Facilities, available in this docket for this action 
(Docket ID EPA-HQ-OAR-2017-0015).

 Table 8--Proximity Demographic Assessment Results for Major Source Lime
                        Manufacturing Facilities
------------------------------------------------------------------------
                                                       Population within
        Demographic group             Nationwide      5 km of facilities
------------------------------------------------------------------------
Total Population................  328,016,242.......  473,343.
------------------------------------------------------------------------
                      Race and Ethnicity by Percent
------------------------------------------------------------------------
White...........................  60 percent........  50 percent.
Black...........................  12 percent........  9 percent.
Native American.................  0.7 percent.......  0.9 percent.
Hispanic or Latino (includes      19 percent........  37 percent.
 white and nonwhite).
Other and Multiracial...........  8 percent.........  3 percent.
------------------------------------------------------------------------

[[Page 9100]]

 
                            Income by Percent
------------------------------------------------------------------------
Below Poverty Level.............  13 percent........  27 percent.
Above Poverty Level.............  87 percent........  73 percent.
------------------------------------------------------------------------
                          Education by Percent
------------------------------------------------------------------------
Over 25 and without a High        12 percent........  17 percent.
 School Diploma.
Over 25 and with a High School    88 percent........  83 percent.
 Diploma.
------------------------------------------------------------------------
                   Linguistically Isolated by Percent
------------------------------------------------------------------------
Linguistically Isolated.........  5 percent.........  21 percent.
------------------------------------------------------------------------
Notes:
 Nationwide population and demographic percentages are based on
  the Census' 2015-2019 American Community Survey 5-year block group
  averages and include Puerto Rico. Demographic percentages based on
  different averages may differ. The total population counts within 5 km
  of all facilities are based on the 2010 Decennial Census block
  populations.
 Minority population is the total population minus the white
  population.
 To avoid double counting, the ``Hispanic or Latino'' category
  is treated as a distinct demographic category for these analyses. A
  person is identified as one of five racial/ethnic categories above:
  White, Black, Native American, Other and Multiracial, or Hispanic/
  Latino. A person who identifies as Hispanic or Latino is counted as
  Hispanic/Latino for this analysis, regardless of what race this person
  may have also identified as in the Census.

    The human health risk estimated for this source category for the 
July 24, 2020, RTR (85 FR 44960) was determined to be acceptable, and 
the standards were determined to provide an ample margin of safety to 
protect public health. Specifically, the maximum individual cancer risk 
was 1-in-1 million for actual emissions (2-in-1 million for allowable 
emissions) and the noncancer hazard indices for chronic exposure were 
well below 1 (0.04 for actual emissions, 0.05 for allowable emissions). 
The noncancer hazard quotient for acute exposure was 0.6, also below 1. 
The proposed changes to the NESHAP subpart AAAAA will reduce emissions 
by 905 tons of HAP per year, and therefore, further improve human 
health exposures for the populations and individuals most exposed to 
this pollution, including communities with environmental justice 
concerns . The proposed changes will have beneficial effects on air 
quality and public health for populations exposed to emissions from 
lime manufacturing facilities.

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

    In the July 24, 2020, final Lime Manufacturing NESHAP RTR (85 FR 
44960), the EPA conducted a residual risk assessment and determined 
that risk from the lime manufacturing source category was acceptable, 
and the standards provided an ample margin of safety to protect public 
health. This action proposes first-time emissions standards for HCl, 
mercury, organic HAP, and D/F. Specifically, compliance with the 
emission standards set in this proposed rule will result in a combined 
reduction of total HAP of 905 tons of HAP per year.
    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 2020 RTR rule, which is available in the docket 
(Docket ID No. EPA-HQ-OAR-2017-0015).

V. Request for Comments

    We solicit comments on all aspects of this proposed action. In 
addition to general comments on this proposed action, we are also 
interested in additional data that may improve the analyses. We are 
specifically interested in receiving any information regarding 
developments in practices, processes, and control technologies that 
reduce HAP emissions. We request comment on the assumptions regarding 
the costs of capital, work practices, and emissions. We request comment 
of all aspects of the economic impacts of this proposal.

VI. Submitting Data Corrections

    The site-specific emissions data used in setting MACT standards for 
HCl, mercury, organic HAP, and D/F, as emitted from the lime 
manufacturing source category, are provided in the docket for this 
rulemaking (Docket ID No. EPA-HQ-OAR-2017-0015).
    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.

VII. 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 13563 Improving 
Regulation and Regulatory Review

    This action is a ``significant regulatory action'' as defined in 
Executive Order 12866, as amended by Executive Order 14094. 
Accordingly, the EPA submitted

[[Page 9101]]

this action to the Office of Management and Budget (OMB) for Executive 
Order 12866 review. Documentation of any changes made in response to 
the Executive Order 12866 review is available in the docket. The EPA 
prepared an economic analysis of the potential impacts associated with 
this action. This analysis is included in the document titled, 
Regulatory Impact Analysis for the Supplemental Proposed Amendments to 
the National Emission Standards for Hazardous Air Pollutants: Lime 
Manufacturing Plants and is also available in the docket.

B. Paperwork Reduction Act (PRA)

    The information collection activities in this proposed rule have 
been submitted for approval to the OMB under the PRA. The Information 
Collection Request (ICR) document that the EPA prepared has been 
assigned EPA ICR number 2072.10. You can find a copy of the ICR in the 
docket for this rule, and it is briefly summarized here.
    We are proposing changes to the reporting and recordkeeping 
requirements for the Lime Manufacturing Plants NESHAP by incorporating 
the reporting and recordkeeping requirements associated with the new 
and existing source MACT standards for HCl, mercury, THC, and D/F.
    Respondents/affected entities: Owners or operators of lime 
manufacturing plants that are major sources, or that are located at, or 
are part of, major sources of HAP emissions, unless the lime 
manufacturing plant is located at a kraft pulp mill, soda pulp mill, 
sulfite pulp mill, sugar beet manufacturing plant, or only processes 
sludge containing calcium carbonate from water softening processes.
    Respondent's obligation to respond: Mandatory (40 CFR part 63, 
subpart AAAAA).
    Estimated number of respondents: On average over the next 3 years, 
approximately 34 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 8.392 hours per year. Burden is defined 
at 5 CFR 1320.3(b).
    Total estimated cost: The annual recordkeeping and reporting costs 
for all facilities to comply with all of the requirements in the NESHAP 
is estimated to be $3,570,000 per year, of which $1,370,000 (first 
year) is for this rule, and the rest is for other costs related to 
continued compliance with the current NESHAP requirements including 
$1,005,000 in annualized capital and operation and maintenance costs.
    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 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 https://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 April 9, 2024.

C. Regulatory Flexibility Act (RFA)

    Pursuant to section 603 of the RFA, the EPA prepared an initial 
regulatory flexibility analysis (IRFA) that examines the impact of the 
proposed rule on small entities along with regulatory alternatives that 
could minimize that impact. The complete IRFA is included as section 
6.3 of the document titled, Regulatory Impact Analysis for the 
Supplemental Proposed Amendments to the National Emission Standards for 
Hazardous Air Pollutants: Lime Manufacturing Plants, for review in the 
docket and is summarized here.
    As discussed in section II.A. of this preamble, the statutory 
authority for this action is provided by sections 112 and 301 of the 
CAA, as amended (42 U.S.C. 7401 et seq.). The EPA is proposing to 
revise the Lime Manufacturing NESHAP by establishing new emission 
standards for this source category, exercising authority under multiple 
provisions of section 112 of the CAA.
    For purposes of assessing the impacts of this rule on small 
entities, a small entity is defined as a small business in the lime 
manufacturing industry whose parent company has revenues or numbers of 
employees below the Small Business Administration (SBA) Size Standards 
for the relevant NAICS code. We have identified 8 different NAICS codes 
of the parent companies within this source category. A complete list of 
those NAICS codes and SBA Size Standards is available in section 6.2.1 
of the document titled, Regulatory Impact Analysis for the Supplemental 
Proposed Amendments to the National Emission Standards for Hazardous 
Air Pollutants: Lime Manufacturing Plants which is included in the 
docket for this rulemaking. This supplemental proposal contains 
provisions that would affect approximately 2 small entities. Under the 
proposed rule requirements, small entities would be required to comply 
with the emission standards of four previously unregulated pollutants, 
which may require the use of new air pollution control devices. Small 
entities would also need to demonstrate compliance with the emission 
standards through periodic performance testing. This supplemental 
proposal includes reporting, recordkeeping, and other administrative 
requirements. The EPA estimates that the two identified small entities 
could incur total annual costs associated with the proposal that are at 
least 3 percent of their annual revenues. Considering the level of 
total annual costs relative to annual sales for these small entities, 
the EPA determined that there is potential for the proposed 
requirements to have a `Significant Impact on a Substantial Number of 
Small Entities' (SISNOSE). See section 6.2.2 of the document titled, 
Regulatory Impact Analysis for the Supplemental Proposed Amendments to 
the National Emission Standards for Hazardous Air Pollutants: Lime 
Manufacturing Plants for more information on the characterization of 
the impacts to small businesses under the proposed rule.
    As required by section 609(b) of the RFA, the EPA also convened a 
Small Business Advocacy Review (SBAR) Panel to obtain advice and 
recommendations from small entity representatives (SERs) that 
potentially would be subject to the rule's requirements. On August 3, 
2023, the EPA's Small Business Advocacy Chairperson convened the Panel, 
which consisted of the Chairperson, the Director of the Sector Policies 
and Programs Division within the EPA's Office of Air Quality Planning 
and Standards, the Administrator of the Office of Information and 
Regulatory Affairs within OMB, and the Chief Counsel for Advocacy of 
the Small Business Administration (SBA).
    Prior to convening the Panel, the EPA conducted outreach and 
solicited comments from the SERs. After the Panel was convened, the 
Panel provided

[[Page 9102]]

additional information to the SERs and requested their input. The 
Panel's review identified several significant alternatives for 
consideration by the Administrator of the EPA which accomplish the 
stated objectives of the CAA and minimize economic impacts of the 
proposed rule on small entities.
    The SBAR Panel recommended several flexibilities including the 
consideration of health-based standards for HCl, an IQV for mercury, an 
aggregated organic HAP emission standard, and work practice standards 
for D/F. The EPA is including some of these flexibilities as a part of 
this supplemental proposal and is soliciting comment on others that may 
be considered for the final rule. The report was finalized and 
transmitted to the EPA Administrator for consideration. A copy of the 
full SBAR Panel Report is available in the docket of this rulemaking.

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. The 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. The EPA does not know of any lime manufacturing 
facilities owned or operated by Indian Tribal governments. Thus, 
Executive Order 13175 does not apply to this action.

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

    Executive Order 13045 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 a significant regulatory action under section 
3(f)(1) of 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. This action proposes 
emission standards for four previously unregulated pollutants; 
therefore, the rule proposes health benefits to children by reducing 
the level of HAP emissions emitted from the lime manufacturing process.
    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 
\23\ 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.
---------------------------------------------------------------------------

    \23\ 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 proposed action, the EPA is 
setting emission standards for previously unregulated pollutant. 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 Lime Manufacturing 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 23, 25A, 29, 30B, 320, and 321. 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 
referenced 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 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.
    Two VCS were identified as acceptable alternatives to the EPA test 
methods for this proposed rule. The VCS ASTM D6784-16, ``Standard Test 
Method for Elemental, Oxidized, Particle-Bound and Total Mercury Gas 
Generated from Coal-Fired Stationary Sources (Ontario Hydro Method)'' 
is an acceptable alternative to EPA Method 29 (portion for mercury 
only) as a method for measuring mercury. The VCS ASTM D6348-12e1, 
``Determination of Gaseous Compounds by Extractive Direct Interface 
Fourier Transform (FTIR) Spectroscopy'' is an acceptable alternative to 
EPA Method 320 with certain conditions. 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: Lime Manufacturing Technology Review'', which 
is available in the docket for this action (Docket ID No. EPA-HQ-OAR-
2017-0015).
    The EPA is incorporating by reference the VCS ASTM D6348-12e1, 
``Determination of Gaseous Compounds by Extractive Direct Interface 
Fourier Transform (FTIR) Spectroscopy,'' as an acceptable alternative 
to EPA Method 320. ASTM D6348-03 (Reapproved 2010) was determined to be 
equivalent to EPA Method 320 with caveats. ASTM D6348-12e1 is a revised 
version of ASTM D6348-03 (Reapproved 2010) and includes a new section 
on accepting the results from the direct measurement of a certified 
spike gas cylinder, but lacks the caveats placed on the ASTM D6348-
03(2010) version. ASTM D6348-12e1 is an extractive FTIR field test 
method used to quantify gas phase concentrations of multiple analytes 
from stationary source effluent and is an acceptable alternative to EPA 
Method 320 at this time with caveats requiring inclusion of selected 
annexes to the standard as mandatory. When using ASTM D6348-12e1, the 
following conditions must be met:
     The test plan preparation and implementation in the 
Annexes to ASTM D6348-03, sections A1 through A8 are mandatory; and
     In ASTM D6348-03, Annex A5 (Analyte Spiking Technique), 
the percent (%) R must be determined for each target analyte (Equation 
A5.5).

[[Page 9103]]

    In order for the test data to be acceptable for a compound, percent 
R must be 70 percent >= R <= 130 percent. If the percent R value does 
not meet this criterion for a target compound, the test data is not 
acceptable for that compound and the test must be repeated for that 
analyte (i.e., the sampling and/or analytical procedure should be 
adjusted before a retest). The percent R value for each compound must 
be reported in the test report, and all field measurements must be 
corrected with the calculated percent R value for that compound by 
using the following equation:
    Reported Results = ((Measured Concentration in Stack))/(percent R) 
x 100.
    The EPA is incorporating by reference 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 
(portion for mercury only) as a method for measuring elemental, 
oxidized, particle-bound, and total mercury concentrations ranging from 
approximately 0.5 to 100 micrograms per normal cubic meter. 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 for the earlier version of the same standard VCS ASTM D6784-
02 (Reapproved 2008).
    ASTM D6784-16 and ASTM D6348-12e1 are available at ASTM 
International, 1850 M Street NW, Suite 1030, Washington, DC 20036. See 
https://www.astm.org/. The standards are available to everyone at a 
cost determined by ASTM ($82). The costs of obtaining these methods are 
not a significant financial burden, making the methods reasonably 
available.
    Additionally, the EPA is incorporating by reference EPA/100/R-10/
005, ``Recommended Toxicity Equivalence Factors (TEFs) for Human Health 
Risk Assessments of 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin and Dioxin-
Like Compounds,'' December 2010, which is the source of the toxicity 
equivalence factors (TEF) for dioxins and furans used in calculating 
the toxic equivalence quotient of the proposed dioxin and furan 
standard. This document describes the EPA's updated approach for 
evaluating the human health risks from exposures to environmental media 
containing dioxin-like compounds. The EPA recommends that the TEF 
methodology, a component mixture method, be used to evaluate human 
health risks posed by these mixtures, using TCDD as the index chemical. 
The EPA recommends the use of the consensus TEF values for 2,3,7,8-
tetrachlorodibenzo-p-dioxin and dioxin-like compounds published in 2005 
by the World Health Organization. EPA/100/R-10/005 is available on the 
EPA website, https://www.epa.gov/risk/documents-recommended-toxicity-equivalency-factors-human-health-risk-assessments-dioxin-and.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations and Low-
Income Populations and Executive Order 14096: Revitalizing Our Nation's 
Commitment to Environmental Justice for All

    The EPA believes 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 communities with environmental justice (EJ) concerns. The 
assessment of populations in close proximity of lime manufacturing 
facilities shows Hispanic and linguistically isolated groups are higher 
than the national average (see section V.E. of the preamble). The 
higher percentages are driven by 4 of the 34 facilities in the source 
category.
    The EPA believes that this action is likely to reduce existing 
disproportionate and adverse effects on communities with EJ concerns. 
The EPA is proposing MACT standards for HCl, mercury, organic HAP, and 
D/F. The EPA expects that the 4 facilities would have to implement 
control measures to reduce emissions to comply with the MACT standards 
and that HAP exposures for the people of color and low-income 
individuals living near these facilities would decrease.
    The EPA will additionally identify and address environmental 
justice concerns by conducting outreach after signature of this 
proposed rule. The EPA will address this rule during the monthly 
Environmental Justice call for communities burdened by disproportionate 
environmental impacts.
    The information supporting these Executive Orders 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. 2024-02299 Filed 2-8-24; 8:45 am]
BILLING CODE 6560-50-P