[Federal Register Volume 88, Number 157 (Wednesday, August 16, 2023)]
[Proposed Rules]
[Pages 55858-55903]
[FR Doc No: 2023-16620]

Vol. 88

Wednesday,

No. 157

August 16, 2023

Part III

Environmental Protection Agency

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

40 CFR Part 63

National Emission Standards for Hazardous Air Pollutants for Coke
Ovens: Pushing, Quenching, and Battery Stacks, and Coke Oven Batteries;
Residual Risk and Technology Review, and Periodic Technology Review;
Proposed Rule

Federal Register / Vol. 88, No. 157 / Wednesday, August 16, 2023 /
Proposed Rules

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

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2002-0085, EPA-HQ-OAR-2003-0051; FRL-8471-01-OAR]
RIN 2060-AV19

National Emission Standards for Hazardous Air Pollutants for Coke
Ovens: Pushing, Quenching, and Battery Stacks, and Coke Oven Batteries;
Residual Risk and Technology Review, and Periodic Technology Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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

SUMMARY: The Environmental Protection Agency (EPA) is proposing
amendments to the National Emissions Standards for Hazardous Air
Pollutants (NESHAP) for Coke Ovens: Pushing, Quenching, and Battery
Stacks (PQBS) source category, and the NESHAP for the Coke Oven
Batteries (COB) source category. This proposal presents the results of
the residual risk and technology review (RTR) conducted as required
under the Clean Air Act (CAA) for the PQBS source category, and the
periodic technology review for the COB source category, also required
under the CAA. The EPA is proposing that risks due to emissions of
hazardous air pollutants (HAP) from the PQBS source category are
acceptable and that the current NESHAP provides an ample margin of
safety to protect public health. Under the technology review for PQBS
NESHAP, we are proposing there are no developments in practices,
processes or control technologies that necessitate revision of
standards for this source category. Under the technology review for the
COB source category, the EPA is proposing amendments to the NESHAP to
lower the limits for leaks from doors, lids, and offtakes to reflect
improvements in technology to minimize emissions. We also are proposing
a requirement for fenceline monitoring for benzene (as a surrogate for
coke oven emissions) and a requirement to conduct root cause analysis
and corrective action upon exceeding an action level. In addition, we
are proposing: (1) new standards for several unregulated HAP or sources
of HAP at facilities subject to PQBS NESHAP; (2) the removal of
exemptions for periods of startup, shutdown, and malfunction consistent
with a 2008 court decision, and clarifying that the standards apply at
all times for both source categories; and (3) the addition of
electronic reporting for performance test results and compliance
reports. We solicit comments on all aspects of this proposed action.

DATES:
    Comments. Comments must be received on or before October 2, 2023.
Under the Paperwork Reduction Act (PRA), comments on the information
collection provisions are best assured of consideration if the Office
of Management and Budget (OMB) receives a copy of your comments on or
before September 15, 2023.
    Public hearing: If anyone contacts us requesting a public hearing
on or before August 21, 2023, we will hold a virtual public hearing.
See SUPPLEMENTARY INFORMATION for information on requesting and
registering for a public hearing.

ADDRESSES: You may send comments, identified by Docket ID Nos. EPA-HQ-
OAR-2002-0085 (Coke Ovens: Pushing, Quenching, and Battery Stacks
source category) and EPA-HQ-OAR-2003-0051 (Coke Oven Batteries source
category) by any of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov/
(our preferred method). Follow the online instructions for submitting
comments.
     Email: [email protected]. Include Docket ID Nos. EPA-
HQ-OAR-2002-0085 or EPA-HQ-OAR-2003-0051 in the subject line of the
message.
     Fax:<PHONE_NUMBER>. Attention Docket ID Nos. EPA-HQ-OAR-
2002-0085 or EPA-HQ-OAR-2003-0051.
     Mail: U.S. Environmental Protection Agency, EPA Docket
Center, Docket ID Nos. EPA-HQ-OAR-2002-0085 or EPA-HQ-OAR-2003-0051,
Mail Code 28221T, 1200 Pennsylvania Avenue NW, Washington, DC 20460.
     Hand/Courier Delivery: EPA Docket Center, WJC West
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004.
The Docket Center's hours of operation are 8:30 a.m.-4:30 p.m., Monday-
Friday (except federal holidays).
    Instructions: All submissions received must include the Docket ID
Nos. for this rulemaking. Comments received may be posted without
change to https://www.regulations.gov/, including any personal
information provided. For detailed instructions on sending comments and
additional information on the rulemaking process, see the SUPPLEMENTARY
INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed
action, contact Donna Lee Jones, Sector Policies and Programs Division
(MD-243-02), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711; telephone number:<PHONE_NUMBER>; email address:
[email protected]. For specific information regarding the risk
modeling methodology, contact Michael Moeller, Health and Environmental
Impacts Division (C539-02), Office of Air Quality Planning and
Standards, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina 27711; telephone number:<PHONE_NUMBER>; email
address: [email protected].

SUPPLEMENTARY INFORMATION:
    Participation in virtual public hearing. To request a virtual
public hearing, contact the public hearing team at<PHONE_NUMBER> or by
email at [email protected]. If requested, the hearing will be
held via virtual platform on August 31, 2023. The hearing will convene
at 11:00 a.m. Eastern Time (ET) and will conclude at 3:00 p.m. ET. The
EPA may close a session 15 minutes after the last pre-registered
speaker has testified if there are no additional speakers. The EPA will
announce further details at https://www.epa.gov/stationary-sources-air-pollution/coke-ovens-pushing-quenching-and-battery-stacks-national-emission or https://www.epa.gov/stationary-sources-air-pollution/coke-ovens-batteries-national-emissions-standards-hazardous-air.
    If a public hearing is requested, the EPA will begin pre-
registering speakers for the hearing no later than 1 business day after
a request has been received. To register to speak at the virtual
hearing, please use the online registration form available at https://www.epa.gov/stationary-sources-air-pollution/coke-ovens-pushing-quenching-and-battery-stacks-national-emission or https://www.epa.gov/stationary-sources-air-pollution/coke-ovens-batteries-national-emissions-standards-hazardous-air, or contact the public hearing team
at<PHONE_NUMBER> or by email at [email protected]. The last
day to pre-register to speak at the hearing will be August 28, 2023.
Prior to the hearing, the EPA will post a general agenda that will list
pre-registered speakers in approximate order at: https://www.epa.gov/stationary-sources-air-pollution/coke-ovens-pushing-quenching-and-battery-stacks-national-emission, or https://www.epa.gov/stationary-sources-air-pollution/coke-ovens-batteries-national-emissions-standards-hazardous-air.
    The EPA will make every effort to follow the schedule as closely as

possible on the day of the hearing; however, please plan for the
hearings to run either ahead of schedule or behind schedule.
    Each commenter will have 4 minutes to provide oral testimony. The
EPA encourages commenters to provide the EPA with a copy of their oral
testimony electronically (via email) by emailing it to
[email protected]. The EPA also recommends submitting the text of
your oral testimony as written comments to the rulemaking docket.
    The EPA may ask clarifying questions during the oral presentations
but will not respond to the presentations at that time. Written
statements and supporting information submitted during the comment
period will be considered with the same weight as oral testimony and
supporting information presented at the public hearing.
    Please note that any updates made to any aspect of the hearing will
be posted online at https://www.epa.gov/stationary-sources-air-pollution/coke-ovens-pushing-quenching-and-battery-stacks-national-emission, or https://www.epa.gov/stationary-sources-air-pollution/coke-ovens-batteries-national-emissions-standards-hazardous-air. While the
EPA expects the hearing to go forward as set forth above, please
monitor our website or contact the public hearing team at (888) 372-
8699 or by email at [email protected] to determine if there are
any updates. The EPA does not intend to publish a document in the
Federal Register announcing updates.
    If you require the services of a translator or special
accommodation such as audio description, please pre-register for the
hearing with the public hearing team and describe your needs by August
23, 2023. The EPA may not be able to arrange accommodations without
advanced notice.
    Docket. The EPA has established dockets for this rulemaking under
Docket ID Nos. EPA-HQ-OAR-2002-0085 (Coke Ovens: Pushing, Quenching,
and Battery Stacks source category) and EPA-HQ-OAR-2003-0051 (Coke Oven
Batteries source category). All documents in the dockets 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 Nos. EPA-HQ-OAR-
2002-0085 and EPA-HQ-OAR-2003-0051. 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's
EPA-HQ-OAR-2002-0085 or EPA-HQ-OAR-2003-0051. The mailed CBI material
should be double wrapped and clearly marked. Any CBI markings should
not show through the outer envelope.
    Preamble acronyms and abbreviations. Throughout this preamble the
use of ``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We
use multiple acronyms and terms in this preamble. While this list may
not be exhaustive, to ease the reading of this preamble and for
reference purposes, the EPA defines the following terms and acronyms
here:

1-BP 1-bromopropane
ACI activated carbon injection
AEGL acute exposure guideline level
AERMOD air dispersion model used by the HEM model
B/W Bypass/Waste
BTF beyond-the-floor
ByP by-product recovery coke production process
CAA Clean Air Act
CalEPA California EPA
CBI confidential business information
CBRP coke by-product chemical recovery plant
CFR Code of Federal Regulations
COE coke oven emissions
delta c lowest concentration subtracted from the highest
concentration
EPA Environmental Protection Agency
ERPG emergency response planning guideline
ERT electronic reporting tool
FGD flue gas desulfurization
gr/dscf grains per dry standard cubic feet
HAP hazardous air pollutant(s)
HCl hydrochloric acid
HCN hydrogen cyanide
HEM human exposure model
HF hydrogen fluoride
HI hazard index
HNR heat and nonrecovery, or only nonrecovery, no heat
HQ hazard quotient
HRSG heat recovery steam generator
IBR incorporation by reference
IRIS integrated risk information system
km kilometer
LAER lowest achievable emissions rate
lb/ton pounds per ton
MACT maximum achievable control technology
mg/L milligrams per liter
mg/m\3\ milligrams per cubic meter
MIR maximum individual risk
NAAQS national ambient air quality standards
NAICS North American Industry Classification System
NESHAP national emission standards for hazardous air pollutants
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards
OMB Office of Management and Budget
PAH polycyclic aromatic hydrocarbons
PB-HAP hazardous air pollutants known to be persistent and bio-
accumulative in the environment
PM particulate matter
POM polycyclic organic matter
ppm parts per million
RDL representative detection limit
REL reference exposure level
RFA Regulatory Flexibility Act
RfC reference concentration
RfD reference dose
RTR residual risk and technology review
SAB Science Advisory Board
SO2 sulfur dioxide
SSM startup, shutdown, and malfunction
TBD to be determined
TOSHI target organ-specific hazard index
tpy tons per year
TRIM.FaTE total risk integrated methodology.fate, transport, and
ecological exposure model
UF uncertainty factor
UPL upper prediction limit
[micro]g/m\3\ microgram per cubic meter
UMRA Unfunded Mandates Reform Act
URE unit risk estimate
VCS voluntary consensus standards
VE visible emissions
WAS wet alkaline scrubber

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

I. General Information
    A. Executive Summary
    B. Does this action apply to me?
    C. 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 are the source categories and how do the current NESHAPs
regulate HAP emissions?
    C. What data collection activities were conducted to support
this action?
    D. What other relevant background information and data were
available?
III. Analytical Procedures and Decision-Making
    A. How do we consider risk in our decision-making?
    B. How do we perform the technology review?
    C. How do we estimate post-MACT risk posed by the coke ovens:
pushing, quenching, and battery stacks source category?
IV. Analytical Results and Proposed Decisions
    A. What actions are we taking pursuant to CAA sections 112(d)(2)
and 112(d)(3)?
    B. What are the results of the risk assessment and analyses for
coke ovens: pushing, quenching, and battery stacks source category?
    C. What are our proposed decisions regarding risk acceptability,
ample margin of safety, and adverse environmental effect?
    D. What are the results and proposed decisions based on our
technology review?
    E. What other actions are we proposing?
    F. What compliance dates are we proposing?
    G. Adding 1-bromopropane to List of HAP
V. Summary of Cost, Environmental, and Economic Impacts
    A. What are the affected sources?
    B. What are the air quality impacts?
    C. What are the other environmental impacts?
    D. What are the cost impacts?
    E. What are the economic impacts?
    F. What are the benefits?
    G. What analysis of environmental justice did we conduct?
    H. What analysis of children's environmental health did we
conduct?
VI. Request for Comments
VII. Submitting Data Corrections
VIII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 14094: Modernizing Regulatory Review
    B. Paperwork Reduction Act (PRA)
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations

I. General Information

A. Executive Summary

1. Purpose of the Regulatory Action
    The EPA is proposing amendments to the NESHAP for Coke Ovens:
Pushing, Quenching, and Battery Stacks and the NESHAP for Coke Oven
Batteries. The purpose of this proposed action is to fulfill the EPA's
statutory obligations pursuant to Clean Air Act (CAA) sections
112(d)(2), (d)(3) and (d)(6) and improve the emissions standards for
the Coke Oven Batteries and Coke Ovens Pushing, Quenching, and Battery
Stacks source categories based on information regarding developments in
practices, processes, and control technologies (``technology review'').
In addition, this action fulfills the EPA's statutory obligations
pursuant to CAA section 112(f)(2) to evaluate the maximum achievable
control technology (MACT) standards for the Coke Ovens Pushing,
Quenching, and Battery Stacks source category to determine whether
additional standards are needed to address any remaining risk
associated with HAP emissions from this Coke Ovens Pushing, Quenching,
and Battery Stacks source category (``residual risk review'').
2. Summary of the Major Provisions of This Regulatory Action
    The EPA is proposing amendments under the technology review for the
Coke Oven Batteries NESHAP pursuant to CAA section 112(d)(6),
including: (1) revising the emission leak limits for coke oven doors,
lids, and offtakes; and (2) requiring fenceline monitoring for benzene
along with an action level for benzene (as a surrogate for coke oven
emissions (COE)) and a requirement for root cause analysis and
corrective actions if the action level is exceeded.

    Under the technology review for the Coke Ovens Pushing, Quenching,
and Battery Stacks NESHAP pursuant to CAA section 112(d)(6), the EPA
did not identify any cost-effective options to reduce actual emissions
from currently regulated sources under the Coke Ovens Pushing,
Quenching, and Battery Stacks NESHAP. However, EPA is asking for
comment on whether a 1-hour opacity standard would identify short-term
periods of high opacity that are not identified from the current 24-
hour standard of 15 percent opacity; and on whether COE are emitted
from ovens after being pushed and while they are waiting to be charged
again (i.e., ``soaking emissions'').
    As part of the technology review, the EPA must also set MACT
standards for previously unregulated HAP emissions pursuant to CAA
sections 112(d)(2) and (3). The EPA identified 17 unregulated HAP or
emissions sources from Coke Ovens Pushing, Quenching, and Battery
Stacks sources including hydrogen chloride (HCl), hydrogen fluoride
(HF), mercury (Hg), and PM metals (e.g., lead and arsenic) from heat
nonrecovery (HNR) facility heat recovery steam generators (HRSG) main
stacks and bypass/waste (B/W) stacks, and HCl, HF, hydrogen cyanide
(HCN), Hg, and PM metals from pushing and coke oven battery stacks. In
this action, under the authority of CAA sections 112(d)(2) and (3), we
are proposing MACT floor limits (i.e., the minimum stringency level
allowed by the CAA) for 15 of the 17 unregulated HAP and beyond the
floor limits (i.e., more stringent than the MACT floor) for two HAP
(mercury and nonmercury HAP metals) from B/W stacks.
    With regard to the residual risk review for the Coke Pushing,
Quenching, and Battery Stacks NESHAP pursuant to CAA section 112(f)(2),
the estimated inhalation maximum individual risk (MIR) for cancer for
the baseline scenario (i.e., current actual emissions levels) due to
HAP emissions from Coke Ovens Pushing, Quenching, and Battery Stacks
sources is 9-in-1 million, and the MIR based on allowable emissions was
only slightly higher (10-in-1 million), as shown in Table 1.
Furthermore, all estimated noncancer risks are below a level of
concern. Based on these risk results and subsequent evaluation of
potential controls (e.g., costs, feasibility and impacts) that could be
applied to reduce these risks even further, we are proposing that risks
due to HAP emissions from the Coke Ovens Pushing, Quenching, and
Battery Stacks source category are acceptable and the Coke Ovens
Pushing, Quenching, and Battery Stacks NESHAP provides an ample margin
of safety to protect public health. Therefore, we are not proposing
amendments under CAA section 112(f)(2); however, we note that the
proposed BTF MACT limit for B/W stacks would reduce the estimated MIR
from 9-in-1 million to 2-in-1 million, and the population estimated to
be exposed to cancer risks greater than or equal to 1-in-1 million
would be reduced from approximately 2,900 to 390. However, the whole
facility cancer MIR (the maximum cancer risk posed by all sources of
HAP at coke oven facilities) would remain unchanged, at 50-in-1 million
because the whole facility MIR is driven by the estimated actual
current fugitive emissions from coke oven doors (as described in
section IV.B. of this preamble) and we do not expect reductions of the
actual emissions from doors as a result of this proposed rule (as
explained further in section IV.D. of this preamble).

                              Table 1--Summary of Estimated Cancer Risk Reductions
----------------------------------------------------------------------------------------------------------------
                                                                 Inhalation          Population cancer risk
                                                                 cancer risk  ----------------------------------
                             Item                             ----------------  Estimated annual
                                                                  MIR in 1      cancer incidence     >= 1-in-1
                                                                   million      (cases per year)      million
----------------------------------------------------------------------------------------------------------------
Coke Ovens Pushing, Quenching, and Battery Stacks Source                    9               0.02           2,900
 Category....................................................
Post Control Risks for the Coke Ovens Pushing, Quenching, and               2           \a\ 0.02             390
 Battery Stacks Source Category..............................
Whole Facility...............................................              50                0.2            2.7M
Post Control Whole Facility Risks............................              50                0.2            2.7M
----------------------------------------------------------------------------------------------------------------
\a\ The estimated incidence of cancer due to inhalation exposures is 0.02 excess cancer case per year (or 1 case
  every 50 years) and stays approximately the same due to emission reductions as a result of this proposed
  action.

    Furthermore, we conducted a demographics analysis, which indicates
that the population within 10 km of the coke oven facilities with risks
greater than or equal to 1-in-1 million is disproportionately African
American.
    With regard to other actions, we are proposing the removal of
exemptions for periods of startup, shutdown, and malfunction consistent
with a 2008 court decision, Sierra Club v. EPA, 551 F.3d 1019 (D.C.
Cir. 2008), and clarifying that the emissions standards apply at all
times; and the addition of electronic reporting for performance test
results and compliance reports for both NESHAPs.
    With regard to costs and emissions reductions, we estimate that the
proposed BTF limits for B/W stacks will achieve an estimated 237 tons
per year (tpy) reduction of PM emissions, 14 tpy of PM2.5
emissions, 4.0 tpy reduction of nonmercury metal HAP emissions, and 144
pounds per year reduction of mercury emissions. The total capital costs
for the industry (for 1 facility) are estimated to be $7.5M and the
estimated annual costs for the industry for all proposed requirements
are about $9.1M/yr for 11 affected facilities.

B. Does this action apply to me?

    Table 2 of this preamble lists the NESHAP and associated regulated
industrial source categories that are the subjects of this proposal.
Table 2 is not intended to be exhaustive, but rather provides a guide
for readers regarding the entities that this proposed action is likely
to affect. The proposed standards, once promulgated, will be directly
applicable to the affected sources. Federal, state, local, and tribal
government entities would not be affected by this proposed action. As
defined in the Initial List of Categories of Sources Under Section
112(c)(1) of the Clean Air Act Amendments of 1990 (see 57 FR 31576,
July 16, 1992) and Documentation for Developing the Initial Source
Category List, Final Report (see EPA-450/3-91-030, July 1992), the Coke
Ovens: Pushing, Quenching, and Battery Stacks source category includes
emissions from pushing and quenching operations, and battery stacks at
a coke oven facility. The Coke Oven Batteries source category includes
emissions from the batteries themselves. A coke oven facility is
defined as a facility engaged in the manufacturing of metallurgical

coke by the destructive distillation of coal.

 Table 2--NESHAP and Source Categories Affected by This Proposed Action
------------------------------------------------------------------------
         Source category                NESHAP          NAICS Code \a\
------------------------------------------------------------------------
Coke Ovens: Pushing, Quenching,   40 CFR part 63,     331110 Iron and
 and Battery Stacks.               subpart CCCCC.      Steel Mills and
                                                       Ferroalloy
                                                       Manufacturing.
Coke Oven Batteries.............  40 CFR part 63,     324199 All Other
                                   subpart L.          Petroleum and
                                                       Coal Products
                                                       Manufacturing.
------------------------------------------------------------------------
\a\ North American Industry Classification System.

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

    In addition to being available in the docket, an electronic copy of
this action is available on the internet. Following signature by the
EPA Administrator, the EPA will post a copy of this proposed action at
https://www.epa.gov/stationary-sources-air-pollution/coke-ovens-pushing-quenching-and-battery-stacks-national-emission and https://www.epa.gov/stationary-sources-air-pollution/coke-ovens-batteries-national-emissions-standards-hazardous-air. Following publication in
the Federal Register, the EPA will post the Federal Register version of
the proposal and key technical documents at these same websites.
Information on the overall residual risk and technology review (RTR)
program is available at https://www3.epa.gov/ttn/atw/rrisk/rtrpg.html.
    A memorandum showing the rule edits that would be necessary to
incorporate the changes to 40 CFR part 63, subpart CCCCC and 40 CFR
part 63, subpart L proposed in this action are available in the dockets
(Docket ID Nos. EPA-HQ-OAR-2002-0085 and EPA-HQ-OAR-2003-0051).
Following signature by the EPA Administrator, the EPA also will post a
copy of this document to https://www.epa.gov/stationary-sources-air-pollution/coke-ovens-pushing-quenching-and-battery-stacks-national-emission and https://www.epa.gov/stationary-sources-air-pollution/coke-ovens-batteries-national-emissions-standards-hazardous-air.

II. Background

A. What is the statutory authority for this action?

    The statutory authority for this action is provided by sections 112
of the Clean Air Act (CAA), as amended (42 U.S.C. 7401 et seq.).
Section 112 of the CAA establishes a two-stage regulatory process to
develop standards for emissions of hazardous air pollutants (HAP) from
stationary sources. Generally, the first stage involves establishing
technology-based standards and the second stage involves evaluating
those standards that are based on maximum achievable control technology
(MACT) to determine whether additional standards are needed to address
any remaining risk associated with HAP emissions. This second stage is
commonly referred to as the ``residual risk review.'' In addition to
the residual risk review, the CAA also requires the EPA to review
standards set under CAA section 112 every 8 years and revise the
standards as necessary taking into account any ``developments in
practices, processes, or control technologies.'' This review is
commonly referred to as the ``technology review.'' When the two reviews
are combined into a single rulemaking, it is commonly referred to as
the ``risk and technology review.'' The discussion that follows
identifies the most relevant statutory sections and briefly explains
the contours of the methodology used to implement these statutory
requirements. A more comprehensive discussion appears in the document
titled CAA Section 112 Risk and Technology Reviews: Statutory Authority
and Methodology, in the docket for this rulemaking.
    In the first stage of the CAA section 112 standard setting process,
the EPA promulgates technology-based standards under CAA section 112(d)
for categories of sources identified as emitting one or more of the HAP
listed in CAA section 112(b). Sources of HAP emissions are either major
sources or area sources, and CAA section 112 establishes different
requirements for major source standards and area source standards.
``Major sources'' are those that emit or have the potential to emit 10
tons per year (tpy) or more of a single HAP or 25 tpy or more of any
combination of HAP. All other sources are ``area sources.'' For major
sources, CAA section 112(d)(2) provides that the technology-based
NESHAP must reflect the maximum degree of emission reductions of HAP
achievable (after considering cost, energy requirements, and nonair
quality health and environmental impacts). These standards are commonly
referred to as MACT standards. CAA section 112(d)(3) also establishes a
minimum control level for MACT standards, known as the MACT ``floor.''
In certain instances, as provided in CAA section 112(h), the EPA may
set work practice standards in lieu of numerical emission standards.
Pursuant to CAA sections 112(d)(2) and (3), the EPA must also consider
control options that are more stringent than the floor. Standards more
stringent than the floor are commonly referred to as beyond-the-floor
(BTF) MACT standards. The EPA evaluates whether BTF standards are
needed based on emission reductions, costs of control, and other
factors. If EPA determines that there are potential BTF standards that
might be cost-efffective, the EPA typicallly develops and evaluates
those BTF control options. After evaluating the BTF options, the EPA
typically proposes such BTF options if EPA determines those BTF options
under consideration are technically feasible, costs impacts are
reasonable, and that the BTF standard would achieve meaningful
reductions and not result in significant non-air impacts such as
impacts to other media or excessive energy use. For area sources, CAA
section 112(d)(5) gives the EPA discretion to set standards based on
generally available control technologies or management practices (GACT
standards) in lieu of MACT standards.
    The second stage in standard-setting focuses on identifying and
addressing any remaining (i.e., ``residual'') risk pursuant to CAA
section 112(f). For source categories subject to MACT standards,
section 112(f)(2) of the CAA requires the EPA to determine whether
promulgation of additional standards is needed to provide an ample
margin of safety to protect public health or to prevent an adverse
environmental effect. Section 112(d)(5) of the CAA provides that this
residual risk review is not required for categories of area sources
subject to GACT standards. Section 112(f)(2)(B) of the CAA further
expressly preserves the EPA's use of the two-step approach for
developing standards to address any residual risk

and the Agency's interpretation of ``ample margin of safety'' developed
in the National Emissions Standards for Hazardous Air Pollutants:
Benzene Emissions from Maleic Anhydride Plants, Ethylbenzene/Styrene
Plants, Benzene Storage Vessels, Benzene Equipment Leaks, and Coke By-
Product Recovery Plants (Benzene NESHAP) (54 FR 38044, September 14,
1989). The EPA notified Congress in the Residual Risk Report that the
Agency intended to use the Benzene NESHAP approach in making CAA
section 112(f) residual risk determinations (EPA-453/R-99-001, p. ES-
11). The EPA subsequently adopted this approach in its residual risk
determinations and the United States Court of Appeals for the District
of Columbia Circuit upheld the EPA's interpretation that CAA section
112(f)(2) incorporates the approach established in the Benzene NESHAP.
See NRDC v. EPA, 529 F.3d 1077, 1083 (D.C. Cir. 2008).
    The approach incorporated into the CAA and used by the EPA to
evaluate residual risk and to develop standards under CAA section
112(f)(2) is a two-step approach. In the first step, the EPA determines
whether risks are acceptable. This determination ``considers all health
information, including risk estimation uncertainty, and includes a
presumptive limit on maximum individual lifetime [cancer] risk (MIR)
\1\ of approximately 1 in 10 thousand.'' (54 FR 38045). If risks are
unacceptable, the EPA must determine the emissions standards necessary
to reduce risk to an acceptable level without considering costs. In the
second step of the approach, the EPA considers whether the emissions
standards provide an ample margin of safety to protect public health
``in consideration of all health information, including the number of
persons at risk levels higher than approximately 1 in 1 million, as
well as other relevant factors, including costs and economic impacts,
technological feasibility, and other factors relevant to each
particular decision.'' Id. The EPA must promulgate emission standards
necessary to provide an ample margin of safety to protect public health
or determine that the standards being reviewed provide an ample margin
of safety without any revisions. After conducting the ample margin of
safety analysis, we consider whether a more stringent standard is
necessary to prevent, taking into consideration costs, energy, safety,
and other relevant factors, an adverse environmental effect.
---------------------------------------------------------------------------

    \1\ Although defined as ``maximum individual risk,'' MIR refers
only to cancer risk. MIR, one metric for assessing cancer risk, is
the estimated risk if an individual were exposed to the maximum
level of a pollutant for a lifetime.
---------------------------------------------------------------------------

    CAA section 112(d)(6) separately requires the EPA to review
standards promulgated under CAA section 112 and revise them ``as
necessary (taking into account developments in practices, processes,
and control technologies)'' no less often than every 8 years. In
conducting this review, which we call the ``technology review,'' the
EPA is not required to recalculate the MACT floors that were
established during earlier rulemakings. Natural Resources Defense
Council (NRDC) v. EPA, 529 F.3d 1077, 1084 (D.C. Cir. 2008).
Association of Battery Recyclers, Inc. v. EPA, 716 F.3d 667 (D.C. Cir.
2013). The EPA may consider cost in deciding whether to revise the
standards pursuant to CAA section 112(d)(6). The EPA is required to
address regulatory gaps, such as missing MACT standards for listed air
toxics known to be emitted from the source category. Louisiana
Environmental Action Network (LEAN) v. EPA, 955 F.3d 1088 (D.C. Cir.
2020).

B. What are the source categories and how do the current NESHAPs
regulate HAP emissions?

    Coke oven facilities produce metallurgical coke from coal in coke
ovens. Coke ovens are chambers of brick or other heat-resistant
material in which coal is heated to separate the coal gas, coal water,
and tar to produce coke. In a coke oven, coal undergoes destructive
distillation to produce coke, which is almost entirely carbon. A coke
oven ``battery'' is a group of ovens connected by common walls. There
are two types of metallurgic coke: (1) furnace coke, which is primarily
used in integrated iron and steel furnaces, along with iron ore pellets
(known as Taconite pellets) and other materials, to produce iron and
steel; and (2) foundry coke, which is primarily used in foundry
furnaces for melting iron to produce iron castings.
    The process begins when a batch of coal is discharged from the coal
bunker into a larry car (i.e., charging vehicle that moves along the
top of the battery). The larry car is positioned over the empty, hot
oven; the lids on the charging ports are removed; and the coal is
discharged from the hoppers of the larry car into the oven. The coal is
heated in the oven in the absence of air to temperatures approaching
2,000 degrees Fahrenheit ([deg]F) which drives off most of the volatile
organic constituents of the coal as gases and vapors, forming coke
which consists almost entirely of carbon. Coking continues for 15 to 18
hours to produce blast furnace coke and 25 to 30 hours to produce
foundry coke.
    At the end of the coking cycle, doors at both ends of the oven are
removed, and the incandescent coke is pushed out of the oven by a ram
that is extended from the pusher machine. The coke is pushed through a
coke guide into a special rail car, called a quench car, which
transports the coke to a quench tower, typically located at the end of
a row of batteries. Inside the quench tower, the hot coke is deluged
with water so that it will not continue to burn after being exposed to
air. The quenched coke is discharged onto an inclined ``coke wharf'' to
allow excess water to drain and to cool the coke.
    This process takes place at two types of facilities: (1) by-product
recovery (ByP) facilities, where chemical by-products are recovered
from coke oven emissions (COE) in a co-located coke by-product chemical
recovery plant (CBRP); or (2) heat and nonrecovery, or only nonrecovery
with no heat recovery (HNR) facilities, where chemicals are not
recovered but heat may be recovered from the exhaust from coke ovens in
a heat recovery steam generator (HRSG).
    The coke production process described above is similar at both
types of facilities, except that at by-product facilities the ovens are
under positive pressure and the organic gases and vapors that evolve
are removed through an offtake system and sent to a CBRP for chemical
recovery and coke oven gas cleaning. The CBRPs are not part of the Coke
Ovens: Pushing, Quenching, and Battery Stacks source category or the
Coke Oven Batteries source category. The CBRPs comprise a separate
source category that is regulated under the 40 CFR part 61, subpart L
NESHAP, which was promulgated in 1989.
    At the HNR facilities and the only nonrecovery with no heat
recovery facilities, as the names imply, the coke production process
does not recover the chemical by-products. Instead, all of the coke
oven gas is burned and the hot exhaust gases can be recovered for the
cogeneration of electricity. Furthermore, the non-recovery ovens are of
a horizontal design (as opposed to the vertical design used in the by-
product process). Ovens at HNR facilities are typically 30 to 45 feet
long, 6 to 12 feet wide, and 5 to 12 feet high. Typically, the
individual ovens at ByP facilities are 36 to 56 feet long, 1 to 2 feet
wide, and 8 to 20 feet high, and each oven holds 15 to 25 tons of coal.
Ovens at ByP facilities operate under positive pressure and,
consequently, leak COE, a HAP, that includes both gases and particulate
matter (PM), via oven door jams (``doors''), charging port lids
(``lids''), offtake ducts (``offtakes''), and during charging. Ovens at
HNR facilities

are designed to operate under negative pressure to reduce or eliminate
leaks but require maintenance and monitoring to ensure constant
operation at negative pressure.
    There are 14 coke facilities in the United States (U.S.). Nine of
these facilities use the ByP process and five use the HNR process, as
listed in Table 3. Of these 14 facilities, 11 are currently operating,
with six ByP process facilities and five HNR facilities. Of the five
HNR facilities, four have HRSGs and one does not. The one facility
without HRSGs sends COE directly to the atmosphere via waste heat
stacks, 24 hours per day, 7 days per week. At the current heat recovery
facilities, each HRSG can be bypassed ranging from 192 to 1,139 hours
per year, depending on the facilities' permits, sending COE directly
into the atmosphere.

                                                              Table 3--Coke Oven Facilities
--------------------------------------------------------------------------------------------------------------------------------------------------------
             Firm name                   Parent company               City                   State              Coke  process       Currently  operating
--------------------------------------------------------------------------------------------------------------------------------------------------------
ABC Coke...........................  Drummond Co...........  Tarrant...............  AL                     ByP                    Yes.
Bluestone..........................  Bluestone.............  Birmingham............  AL                     ByP                    No.
Cleveland-Cliffs...................  Cleveland-Cliffs......  Middletown............  OH                     ByP                    No.
Cleveland-Cliffs...................  Cleveland-Cliffs......  Follansbee............  WV                     ByP                    No.
Cleveland-Cliffs...................  Cleveland-Cliffs......  Burns Harbor..........  IN                     ByP                    Yes.
Cleveland-Cliffs...................  Cleveland-Cliffs......  Monessen..............  PA                     ByP                    Yes.
Cleveland-Cliffs...................  Cleveland-Cliffs......  Warren................  OH                     ByP                    Yes.
EES Coke Battery...................  DTE Vantage...........  Detroit...............  MI                     ByP                    Yes.
Indiana Harbor Coke................  SunCoke Energy........  East Chicago..........  IN                     HNR                    Yes.
Haverhill Coke.....................  SunCoke Energy........  Franklin Furnace......  OH                     HNR                    Yes.
Gateway Coke.......................  SunCoke Energy........  Granite City..........  IL                     HNR                    Yes.
Middletown Coke....................  SunCoke Energy........  Middletown............  OH                     HNR                    Yes.
Jewell Coke........................  SunCoke Energy........  Vansant...............  VA                     HNR                    Yes.
US Steel Clairton..................  United States Steel...  Clairton..............  PA                     ByP                    Yes.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The Coke Ovens: Pushing, Quenching, and Battery Stacks NESHAP
regulates both ByP and HNR facilities. Emissions occur during the
pushing process, where coke oven doors are opened at both ends of the
coke oven and a pusher machine positioned next to the ovens pushes the
incandescent coke from the oven's coke end (or coke side of the
battery) using a ram that is extended from the coal or push end of the
oven (or push side of the battery) to the coke end, where coke then
leaves the oven. Particulate emissions that escape from open ovens
during pushing are collected by particulate control devices such as
baghouses, cyclones, and scrubbers that remove metal HAP in the form of
PM. The Coke Ovens: Pushing, Quenching, and Battery Stacks NESHAP
includes limits for PM emissions (as a surrogate for nonmercury metal
HAPs) from the pushing control device, ranging from 0.01 to 0.04 pounds
per ton (lb/ton), depending on whether the control device is mobile or
stationary, and whether the battery is tall or short, according to the
Coke Ovens: Pushing, Quenching, Battery Stacks NESHAP definitions.\2\
Opacity (which also is a surrogate for nonmercury metal HAPs) during
pushing is limited by the NESHAP to 30 or 35 percent, depending on
whether the battery is short or tall, respectively.
---------------------------------------------------------------------------

    \2\ Tall battery in the Coke Ovens: Pushing, Quenching, Battery
Stacks NESHAP means a ByP coke oven battery with ovens 16.5 feet
(five meters) or more in height; short battery means a ByP coke oven
battery with ovens less than 16.5 feet (five meters) in height. Note
the two rules (40 CFR part 63, subparts CCCCC and L) differ in their
designation of tall ovens (5 meters for subpart 5C and 6 meters for
Coke Oven Batteries NESHAP).
---------------------------------------------------------------------------

    The incandescent coke pushed from the ovens is received by rail
quench cars that travel to the nearby quench tower. In the quenching
process, several thousand gallons of water are sprayed from multiple
ports within the quench tower onto the coke mass to cool it. The quench
towers have baffles along the inside walls to condense any steam and
coke aerosols, which then fall down the inside of the tower and exit as
wastewater. The Coke Ovens: Pushing, Quenching, and Battery Stacks
NESHAP requires that baffles limit the quench towers to 5 percent open
space and that the dissolved solids in the quench water are no greater
than 1,100 milligrams per liter (mg/L). The Coke Ovens: Pushing,
Quenching, and Battery Stacks NESHAP also requires the use of clean
quench water.
    The battery stack that collects the underfire hot gases, which
surround the oven and do not contact the coke or coke gas, into the
oven flues and discharges to the atmosphere is limited to 15 percent
opacity during normal operation, as a daily average, and to 20 percent
opacity during extended coking, as a daily average, which is the period
when the coke ovens are operated at a lower temperature to slow down
the coke-making process.
    The HAP emissions from HRSG main stacks and COE from bypass/waste
heat stacks are not currently regulated by any NESHAP and, therefore,
we are proposing to revise the NESHAP for the Coke Ovens: Pushing,
Quenching, and Battery Stacks source category to add standards for
these emission points. The exhaust from HRSGs currently is controlled
by flue gas desulfurization (FGD) units and baghouses for removal of
sulfur dioxide (SO2) and PM, respectively. The control of PM
also reduces HAP (nonmercury metal) emissions from the baghouse
exhaust.
    The Coke Oven Batteries source category addresses emissions from
both ByP and HNR facilities. At HNR facilities, the NESHAP addresses
emissions from charging and emissions from doors (offtake and lids
leaks also are addressed but only ``if applicable to the new
nonrecovery coke oven battery,'' which they are not). The HNR
facilities are required to have 0 emissions from leaking doors on the
coke oven battery (and 0 emissions from leaking lids to ovens and
offtake systems, if any). Door leaks include emissions from coke oven
doors when they are closed and the oven is in operation. Charging at
HNR facilities involves opening one of the two doors on an oven and
loading coal into the oven using a ``pushing/charging machine.''
Because coal is charged on the ``coal side'' of a HNR battery, there
are no ports with ``lids'' on top of HNR ovens for charging coal as
there are on ByP ovens. The Coke Oven Battery NESHAP (40 CFR part 63,
subpart L), promulgated in 1993, set emission limits (via limiting the
number of seconds of visible emissions (VE)) from doors, lids, and
offtakes at HNR and any new ByP facilities to 0 percent leaking.
    For HNR facilities operating before 2004, the 1993 Coke Oven
Batteries NESHAP required good operating and

maintenance practices to minimize emissions during charging. This
requirement for charging affects only SunCoke's Vansant (Virginia)
facility, which is a nonrecovery coke facility and does not recover
heat. For HNR facilities operating after 2004, which includes the other
four HNR facilities (that are heat recovery) and any future HNR
facilities, the NESHAP regulates charging via PM and opacity limits,
and requires a PM control device and work practices for minimizing VE
during charging.
    For ByP facilities, the Coke Oven Batteries NESHAP regulates
emissions occurring during the charging of coal into the ovens and from
leaking of oven doors, leaking topside charging port lids, and leaking
offtake ducts. The charging process for ByP facilities includes opening
the lids on the charging ports on the top of the ovens and discharging
of coal from hoppers of a car that positions itself over the oven port
and drops coal into the oven. The Coke Oven Batteries NESHAP limits the
number of seconds of visible emissions during a charge at ByP
facilities, as determined by measurements made according to EPA Method
303.
    The emissions from leaks at ByP batteries are regulated under the
Coke Oven Batteries NESHAP by limits on the percent of doors, lids and
offtakes that leak COE. Doors are located on both sides of the ovens.
The offtake system at ByP facilities includes ascension pipes and
collector main offtake ducts that are located on the top of the coke
oven and battery. The Coke Oven Batteries NESHAP established limits for
the percent of leaking doors, lids, and offtakes for the current ByP
coke facilities that are shown in Table 4 and are based on the
regulatory ``track'' of the facilities. The facilities were required by
the CAA section 112(i)(8) to choose either the MACT track or the lowest
achievable emissions rate (LAER) track by 1993 (58 FR 57898). Only one
of the nine ByP coke oven facilities remains as a MACT track facility
today (Cleveland Cliffs, Middletown, OH). The remaining eight existing
ByP facilities are on the LAER track.

                Table 4--Limits for Existing ByP Facilities Under the Coke Oven Batteries NESHAP
----------------------------------------------------------------------------------------------------------------
                                                            Limits by track \a\ and effective date
                                             -------------------------------------------------------------------
                                                   MACT                              LAER
               Emission source               -------------------------------------------------------------------
                                               July 14, 2005
                                               \b\ (residual   January  2010            Residual  Risk
                                                   risk)
----------------------------------------------------------------------------------------------------------------
Percent leaking lids........................             0.4             0.4  TBD \c\.
Percent leaking offtakes....................             2.5             2.5  TBD.
Charging (log \d\) s/charge \e\.............              12              12  TBD.
Percent leaking doors--Tall \f\.............             4.0             4.0  TBD.
Percent leaking doors--All other \g\........             3.3             3.3  TBD.
Percent leaking doors--Foundry \h\..........             3.3             4.0  TBD.
----------------------------------------------------------------------------------------------------------------
\a\ The tracks were established in the 1993 NESHAP for Coke Oven Batteries in a tiered approach (58 FR 57898).
\b\ Established in the 2005 RTR final rule for Coke Oven Batteries (70 FR 19992). Only applies to one current
  ByP facility, which is idle.
\c\ TBD = to be determined, as specified in section 171 of the CAA.
\d\ Log = the logarithmic average of the observations of multiple charges (as opposed to an arithmetic average).
\e\ s/charge = seconds of visible emissions per charge of coal into the oven.
\f\ Tall = doors 20 feet (six meters) or more in height (Coke Oven Batteries).
\g\ All other = all blast furnace coke oven doors that are not tall, i.e., doors less than 20 feet (six meters).
\h\ Foundry = doors on ovens producing foundry coke. Two of the 14 coke oven facilities, both LAER track,
  produce foundry coke exclusively.

    One HNR facility is on the LAER track (SunCoke's Vansant facility
in Virginia) and the other four HNR facilities are under the MACT
track. Any future coke facilities of any type (HNR or ByP) would be
under the MACT track,\3\ but no additional ByP facilities are expected
in the future due to the requirement for 0 percent leaking doors, lids,
and offtakes (as determined by EPA Method 303) for new facilities under
the Coke Oven Batteries NESHAP. The positive pressure operation of ByP
ovens makes it impossible to achieve 0 leaks with the current ByP coke
oven technology.
---------------------------------------------------------------------------

    \3\ See CAA section 112(i)(8)(D).
---------------------------------------------------------------------------

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

    The EPA sent two CAA section 114 information requests to industry
in 2016 and 2022 (CAA section 114 request). The CAA section 114 request
in 2016 was sent to nine parent coke companies, which included a
facility questionnaire and source testing request, and resulted in
information gathered for 11 facilities of which seven were requested to
perform testing. After testing was conducted and data were submitted,
the EPA was notified that one of the CAA section 114 request facilities
(Erie Coke) was shut down in late 2019.
    The 2016 CAA section 114 request questionnaire was composed of ten
parts: owner information, general facility information, regulatory
information, process flow diagrams and plot plans, emission points,
process and emission unit operations, air pollution control and
monitoring equipment, economics/costs, startup and shutdown procedures,
and management practices. The compilation of the facility responses can
be found in the dockets to this proposed rulemaking (EPA-HQ-OAR-2002-
0085 and EPA-HQ-OAR-2003-0051).
    Through the 2016 CAA section 114 request, source test data were
obtained for HAP and PM emissions at the following coke stack sources:
pushing, ByP battery combustion stacks, ByP boiler stacks, HRSG main
stacks, HRSG bypass/waste heat stacks, HNR charging control device
outlets, and quench towers for a total of 18 units among the seven
facilities that performed testing. In addition, results of daily and
monthly EPA Method 303 leak tests were obtained for ByP charging, lids,
doors, and offtakes. The EPA sent each facility its compiled testing
results for review, and corrections, if needed, and incorporated the
facilities' comments and revisions into the final results. The final
compilation of 2016 source testing results can be found in the docket
to this action (EPA-HQ-OAR-2002-0085 and EPA-HQ-OAR-2003-0051).
    The CAA section 114 request in 2022 was sent to six parent
companies, which included a facility questionnaire and source testing
request, and resulted in information gathered for eight facilities. In
the 2022 CAA section 114 request, the 2016 CAA section 114 request
questionnaire was resent to six facilities that already had received
the CAA

section 114 request in 2016 to update if needed and then also sent to
two facilities for the first time. The 2022 CAA section 114 request
also included additional questionnaire sections for work practices that
prevent leaks at ByP facilities; EPA Method 303 leak data for coke oven
doors, lids, offtakes, and charging at ByP coke oven facilities; coke
ByP battery stack opacity data and work practices that prevent stack
limit exceedances; information concerning miscellaneous sources, such
as emergency battery flares; community issues; and paperwork reduction
act estimates. The compilation of the facility responses can be found
in the dockets to this proposed rulemaking (EPA-HQ-OAR-2002-0085 and
EPA-HQ-OAR-2003-0051).
    Through the 2022 CAA section 114 request, source test data were
obtained for volatile and particulate HAP and COE at the following coke
point sources: HRSG main stacks and HRSG bypass/waste heat stacks. In
addition, data and information were obtained for HAP from: the CBRP
cooling towers, light oil condensers, sulfur recovery/desulfurization
units, and flares; EPA Method 303 door leaks from the bench and yard;
and fugitive emissions monitoring at the fenceline and interior on site
locations. The fenceline monitoring requirements and results are
described in much more detail in section IV.D.5. of this preamble. The
CAA section 114 requests sent by EPA and compilation of source testing
results can be found in the docket to this action (EPA-HQ-OAR-2002-0085
and EPA-HQ-OAR-2003-0051).
    The 2016 and 2022 CAA section 114 request responses and other data
for emissions for coke facilities were used to populate the risk
assessment modeling input files and included all source testing results
and relevant questionnaire responses on facility operations (e.g.,
stack parameters, stack locations) as well as estimates for sources not
currently operating.

D. What other relevant background information and data were available?

1. Noncategory Emissions
    The 2017 National Emission Inventory (NEI)/Emission Inventory
System (EIS) data were used to estimate some emissions for the
noncategory sources at coke facilities, such as CBRPs, excess coke oven
gas flares, and other miscellaneous units not related to coke
manufacturing (e.g., process heaters, metal finishing, steel pickling,
annealing furnaces, reheat furnaces, thermal coal dryers, etc.). Other
emissions, such as number of leaking doors, lids, and offtakes and
emissions from charging, which are regulated under Coke Oven Batteries
NESHAP, were obtained from CAA section 114 request responses obtained
in 2016 and 2022.
2. Emissions From CBRP
    The emissions from operations at the CBRP are sources of HAP at ByP
facilities, which are regulated by the Benzene NESHAP for Coke By-
Product Recovery Plants in 40 CFR part 61. We intend to list CBRP
operations (as we are calling the co-located plants at coke ByP
facilities) that currently are addressed under the Benzene NESHAP in 40
CFR part 61, as a source category under CAA section 112(c)(5). We
request additional information on the individual HAP emitted, the
process units that are the source(s) of the HAP emissions, and the
estimated amount of HAP emissions, if known, by these CBRP activities.
Once we have this information, we will be in a better position to
finalize the decision to list and to identify the appropriate scope of
the source category to be listed. Details on the currently available
estimates of CBRP emissions are located in the document: Coke Ovens
Risk and Technology Review: Data Summary,\4\ hereafter referred to as
the ``Data Memorandum,'' available in the docket for this proposed
rulemaking.
---------------------------------------------------------------------------

    \4\ Coke Ovens Risk and Technology Review, Data Summary. D.L.
Jones, U.S. Environmental Protection Agency and G.E. Raymond, RTI
International. U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina. May 1, 2023. Docket ID Nos. EPA-HQ-
OAR-2002-0085 and EPA-HQ-OAR-2003-0051.
---------------------------------------------------------------------------

III. Analytical Procedures and Decision-Making

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

A. How do we consider risk in our decision-making?

    As discussed in section II.A. of this preamble and in the Benzene
NESHAP, in evaluating and developing standards under CAA section
112(f)(2), we apply a two-step approach to determine whether or not
risks are acceptable and to determine if the standards provide an ample
margin of safety to protect public health. As explained in the Benzene
NESHAP, ``the first step judgment on acceptability cannot be reduced to
any single factor'' and, thus, ``[t]he Administrator believes that the
acceptability of risk under [CAA] section 112 is best judged on the
basis of a broad set of health risk measures and information.'' (54 FR
38046). Similarly, with regard to the ample margin of safety
determination, ``the Agency again considers all of the health risk and
other health information considered in the first step. Beyond that
information, additional factors relating to the appropriate level of
control will also be considered, including cost and economic impacts of
controls, technological feasibility, uncertainties, and any other
relevant factors.'' Id.
    The Benzene NESHAP approach provides flexibility regarding factors
the EPA may consider in making determinations and how the EPA may weigh
those factors for each source category. The EPA conducts a risk
assessment that provides estimates of the MIR posed by emissions of HAP
that are carcinogens from each source in the source category, the
hazard index (HI) for chronic exposures to HAP with the potential to
cause noncancer health effects, and the hazard quotient (HQ) for acute
exposures to HAP with the potential to cause noncancer health
effects.\5\ The assessment also provides estimates of the distribution
of cancer risk within the exposed populations, cancer incidence, and an
evaluation of the potential for an adverse environmental effect. The
scope of the EPA's risk analysis is consistent with the explanation in
EPA's response to comments on our policy under the Benzene NESHAP. That
policy, chosen by the Administrator, permits the EPA to consider
multiple measures of health risk. Not only can the MIR be considered,
but also cancer incidence, the presence of noncancer health effects,
and uncertainties of the risk estimates. This allows the effect on the
most exposed individuals to be reviewed as well as the impact on the
general public. The various factors can then be weighed in each
individual case. This approach complies with the Vinyl Chloride mandate
that the Administrator determine an acceptable level of risk to the
public by employing his or her expertise to assess available data. It
also complies with Congressional intent behind the CAA, which did not
exclude use of any particular measure of public health risk from the
EPA's consideration with respect to CAA section 112 regulations, and
thereby implicitly permits consideration of any and all measures of
health risk which the Administrator, in his or her judgment,

believes are appropriate to determining what will ``protect the public
health. (54 FR 38057). Thus, the level of the MIR is only one factor to
be weighed in determining acceptability of risk. The Benzene NESHAP
explained that ``an MIR of approximately one in 10 thousand should
ordinarily be the upper end of the range of acceptability. As risks
increase above this benchmark, they become presumptively less
acceptable under CAA section 112, and would be weighed with the other
health risk measures and information in making an overall judgment on
acceptability. Or, the Agency may find, in a particular case, that a
risk that includes an MIR less than the presumptively acceptable level
is unacceptable in the light of other health risk factors.'' Id. at
38045. In other words, risks that include an MIR above 100-in-1 million
may be determined to be acceptable, and risks with an MIR below that
level may be determined to be unacceptable, depending on all of the
available health information. Similarly, with regard to the ample
margin of safety analysis, the EPA stated in the Benzene NESHAP that:
``EPA believes the relative weight of the many factors that can be
considered in selecting an ample margin of safety can only be
determined for each specific source category. This occurs mainly
because technological and economic factors (along with the health-
related factors) vary from source category to source category.'' Id. at
38061. We also consider the uncertainties associated with the various
risk analyses, as discussed earlier in this preamble, in our
determinations of acceptability and ample margin of safety.
---------------------------------------------------------------------------

    \5\ The MIR is defined as the cancer risk associated with a
lifetime of exposure at the highest concentration of HAP where
people are likely to live. The HQ is the ratio of the potential HAP
exposure concentration to the noncancer dose-response value; the HI
is the sum of HQs for HAP that affect the same target organ or organ
system.
---------------------------------------------------------------------------

    The EPA notes that it has not considered certain health information
to date in making residual risk determinations. At this time, we do not
attempt to quantify the HAP risk that may be associated with emissions
from other facilities that do not include the source categories under
review, mobile source emissions, natural source emissions, persistent
environmental pollution, or atmospheric transformation in the vicinity
of the sources in the categories.
    The EPA understands the potential importance of considering an
individual's total exposure to HAP in addition to considering exposure
to HAP emissions from the source category and facility. We recognize
that such consideration may be particularly important when assessing
noncancer risk, where pollutant-specific exposure health reference
levels (e.g., reference concentrations (RfCs)) are based on the
assumption that thresholds exist for adverse health effects. For
example, the EPA recognizes that, although exposures attributable to
emissions from a source category or facility alone may not indicate the
potential for increased risk of adverse noncancer health effects in a
population, the exposures resulting from emissions from the facility in
combination with emissions from all of the other sources (e.g., other
facilities) to which an individual is exposed may be sufficient to
result in an increased risk of adverse noncancer health effects. In May
2010, the Science Advisory Board (SAB) advised the EPA ``that RTR
assessments will be most useful to decision makers and communities if
results are presented in the broader context of aggregate and
cumulative risks, including background concentrations and contributions
from other sources in the area.'' \6\
---------------------------------------------------------------------------

    \6\ Recommendations of the SAB Risk and Technology Review
Methods Panel are provided in their report, which is available at:
https://www.epa.gov/sites/default/files/2021-02/documents/epa-sab-10-007-unsigned.pdf.
---------------------------------------------------------------------------

    In response to the SAB recommendations, the EPA incorporates
cumulative risk analyses into its RTR risk assessments. The Agency (1)
conducts facility-wide assessments, which include source category
emission points, as well as other emission points within the
facilities; (2) combines exposures from multiple sources in the same
category that could affect the same individuals; and (3) for some
persistent and bioaccumulative pollutants, analyzes the ingestion route
of exposure. In addition, the RTR risk assessments consider aggregate
cancer risk from all carcinogens and aggregated noncancer HQs for all
noncarcinogens affecting the same target organ or target organ system.
    Although we are interested in placing source category and facility-
wide HAP risk in the context of total HAP risk from all sources
combined in the vicinity of each source, we note there are
uncertainties of doing so. Estimates of total HAP risk from emission
sources other than those that we have studied in depth during this RTR
review would have significantly greater associated uncertainties than
the source category or facility-wide estimates.

B. How do we perform the technology review?

    Our technology review primarily focuses on the identification and
evaluation of developments in practices, processes, and control
technologies that have occurred since the MACT standards were
promulgated. Where we identify such developments, we analyze their
technical feasibility, estimated costs, energy implications, and nonair
environmental impacts. We also consider the emission reductions
associated with applying each development. This analysis informs our
decision of whether it is ``necessary'' to revise the emissions
standards. In addition, we consider the appropriateness of applying
controls to new sources versus retrofitting existing sources. For this
exercise, we consider any of the following to be a ``development'':
     Any add-on control technology or other equipment that was
not identified and considered during development of the original MACT
standards;
     Any improvements in add-on control technology or other
equipment (that were identified and considered during development of
the original MACT standards) that could result in additional emissions
reduction;
     Any work practice or operational procedure that was not
identified or considered during development of the original MACT
standards;
     Any process change or pollution prevention alternative
that could be broadly applied to the industry and that was not
identified or considered during development of the original MACT
standards; and
     Any significant changes in the cost (including cost
effectiveness) of applying controls (including controls the EPA
considered during the development of the original MACT standards).
    In addition to reviewing the practices, processes, and control
technologies that were considered at the time we originally developed
or last updated the NESHAP, we review a variety of data sources in our
investigation of potential practices, processes, or controls. We also
review the NESHAP and the available data to determine if there are any
unregulated emissions of HAP within the source categories and evaluate
this data for use in developing new emission standards. See sections
II.C. and II.D. of this preamble for information on the specific data
sources that were reviewed as part of the technology review.

C. How do we estimate post-MACT risk posed by the coke ovens: pushing,
quenching, and battery stacks source category?

    In this section, we provide a complete description of the types of
analyses that we generally perform during the risk assessment process.
In some cases, we do not perform a specific analysis because it is not
relevant. For example, in the absence of emissions of HAP known to be
persistent and

bioaccumulative in the environment (PB-HAP), we would not perform a
multipathway exposure assessment. Where we do not perform an analysis,
we state that we do not and provide the reason. While we present all of
our risk assessment methods, we only present risk assessment results
for the analyses actually conducted (see section IV.B. of this
preamble).
    The EPA conducts a risk assessment that provides estimates of the
MIR for cancer posed by the HAP emissions from each source in the
source category, the HI for chronic exposures to HAP with the potential
to cause noncancer health effects, and the HQ for acute exposures to
HAP with the potential to cause noncancer health effects. The
assessment also provides estimates of the distribution of cancer risk
within the exposed populations, cancer incidence, and an evaluation of
the potential for an adverse environmental effect. The eight sections
that follow this paragraph describe how we estimated emissions and
conducted the risk assessment. The docket for this rulemaking contains
the following document which provides more information on the risk
assessment inputs and models: Residual Risk Assessment for the Coke
Ovens: Pushing, Quenching, and Battery Stacks Source Category in
Support of the 2023 Risk and Technology Review Proposed Rule.\7\ The
methods used to assess risk (as described in the eight primary steps
below) are consistent with those described by the EPA in the document
reviewed by a panel of the EPA's SAB in 2009; \8\ and described in the
SAB review report issued in 2010. They are also consistent with the key
recommendations contained in that report.
---------------------------------------------------------------------------

    \7\ Coke Ovens: Pushing, Quenching, and Battery Stacks Source
Category in Support of the 2023 Risk and Technology Review Proposed
Rule. M. Moeller. U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina. May 1, 2023. Docket ID No. EPA-HQ-
OAR-2002-0085).
    \8\ U.S. EPA. Risk and Technology Review (RTR) Risk Assessment
Methodologies: For Review by the EPA's Science Advisory Board with
Case Studies--MACT I Petroleum Refining Sources and Portland Cement
Manufacturing. EPA-452/R-09-006. June 2009. https://www3.epa.gov/airtoxics/rrisk/rtrpg.html.
---------------------------------------------------------------------------

1. How did we estimate actual emissions and identify the emissions
release characteristics?
    The Coke Ovens: Pushing, Quenching, and Battery Stacks source
category emits HAP from pushing of coke out of ovens, ByP battery
(combustion) stacks, HNR HRSG control device main stacks, and quench
towers; and volatile and particulate COE from HNR HRSG bypass/waste
heat stacks. Emissions estimates and release characteristics for HAP
and COE from the above affected sources at current coke facilities were
derived from stack test data obtained through the 2016 and 2022 CAA
section 114 requests. The derivation of actual emissions estimates and
release characteristics for the emission points are described in the
Data Memoradum,\4\ which is available in the docket for this proposed
rulemaking.
    The affected sources of the Coke Oven Battery NESHAP include COE
leaks from oven doors, charging port lids, and offtakes; charging
control device HAP emissions; and visible fugitive emissions from
charging. Emissions estimates for leaks were derived from EPA Method
303 data submitted as part of the CAA section 114 requests (with
estimates for door leak emissions derived using an equation described
in section IV.D.6. of this preamble). Emissions estimates and release
characteristics for HAP from charging control devices were derived from
stack test data obtained through the CAA section 114 requests. The
derivation of all actual emissions estimates and release
characteristics for sources subject to the Coke Oven Battery NESHAP are
discussed in more detail in the Data Memorandum,\4\ available in the
docket for this proposed rulemaking.
2. How did we estimate MACT-allowable emissions?
    The available emissions data in the RTR emissions dataset include
estimates of the mass of HAP emitted during a specified annual time
period. These ``actual'' emission levels are often lower than the
emission levels allowed under the requirements of the current MACT
standards. The emissions allowed under the MACT standards are referred
to as the ``MACT-allowable'' emissions. We discussed the consideration
of both MACT-allowable and actual emissions in the final Coke Oven
Batteries RTR (70 FR 19992, 19998-19999, April 15, 2005) and in the
proposed and final Hazardous Organic NESHAP RTR (71 FR 34421, 34428,
June 14, 2006, and 71 FR 76603, 76609, December 21, 2006,
respectively). In those actions, we noted that assessing the risk at
the MACT-allowable level is inherently reasonable since that risk
reflects the maximum level facilities could emit and still comply with
national emission standards. We also explained that it is reasonable to
consider actual emissions, where such data are available, in both steps
of the risk analysis, in accordance with the Benzene NESHAP approach.
(54 FR 38044.)
    For pushing, the PM limits in the Coke Ovens: Pushing, Quenching,
and Battery Stacks NESHAP were used along with measured HAP and PM data
from the 2016 CAA section 114 request for pushing operations to
estimate allowable HAP emissions. The ratio of allowable PM based on
the standards to actual PM was multiplied by HAP emissions measured in
the 2016 CAA section 114 request to estimate allowable HAP emissions.
For battery stacks, the ratio of the opacity limits to opacity data
from the 2016 CAA section 114 request was used with HAP test data from
battery stacks from the 2016 CAA section 114 request to develop
allowable HAP emissions for battery stacks. The ratios of the quench
tower water limit for total dissolved solids (TDS) to water TDS test
data from the 2016 CAA section 114 request were used along with test
data for HAP air emissions from the 2016 CAA section 114 request for
the quench tower to estimate allowable HAP air emissions from the
quench tower. For HAP from HRSG main control device stacks and COE from
HRSG bypass/waste heat stacks, allowable emissions were set equal to
actual emissions, developed from 2016 and 2022 CAA section 114 test
request data because the Coke Ovens: Pushing, Quenching, and Battery
Stacks NESHAP currently does not have emission limits for these
sources.
    For sources subject to the Coke Oven Batteries NESHAP, the limits
for COE from doors, lids, offtakes, and charging were used with 2016
and 2022 CAA section 114 request operating data to estimate allowable
emissions from these emission points.
    Further details regarding the development of allowable emissions
estimates using data from source test reports and other parts of the
2016 and 2022 CAA section 114 request responses are provided in the
Data Memorandum\4\ available in the docket for this proposed
rulemaking.
3. How do we conduct dispersion modeling, determine inhalation
exposures, and estimate individual and population inhalation risk?
    Both long-term and short-term inhalation exposure concentrations
and health risk from the source category addressed in this proposal
were estimated using the Human Exposure Model (HEM).\9\ The HEM
performs three primary risk assessment activities: (1) conducting
dispersion modeling to estimate the concentrations of HAP in ambient
air, (2) estimating long-term and short-term inhalation exposures to

individuals residing within 50 kilometers (km) of the modeled sources,
and (3) estimating individual and population-level inhalation risk
using the exposure estimates and quantitative dose-response
information.
---------------------------------------------------------------------------

    \9\ For more information about HEM, go to https://www.epa.gov/fera/risk-assessment-and-modeling-human-exposure-model-hem.
---------------------------------------------------------------------------

a. Dispersion Modeling
    The air dispersion model AERMOD, used by the HEM model, is one of
the EPA's preferred models for assessing air pollutant concentrations
from industrial facilities.\10\ To perform the dispersion modeling and
to develop the preliminary risk estimates, HEM draws on three data
libraries. The first is a library of meteorological data, which is used
for dispersion calculations. This library includes 1 year (2019) of
hourly surface and upper air observations from 838 meteorological
stations selected to provide coverage of the United States and Puerto
Rico. A second library of United States Census Bureau census block \11\
internal point locations and populations provides the basis of human
exposure calculations (U.S. Census, 2010). In addition, for each census
block, the census library includes the elevation and controlling hill
height, which are also used in dispersion calculations. A third library
of pollutant-specific dose-response values is used to estimate health
risk. These are discussed below.
---------------------------------------------------------------------------

    \10\ U.S. EPA. Revision to the Guideline on Air Quality Models:
Adoption of a Preferred General Purpose (Flat and Complex Terrain)
Dispersion Model and Other Revisions (70 FR 68218, November 9,
2005).
    \11\ A census block is the smallest geographic area for which
census statistics are tabulated.
---------------------------------------------------------------------------

b. Risk From Chronic Exposure to HAP
    In developing the risk assessment for chronic exposures, we use the
estimated annual average ambient air concentrations of each HAP emitted
by each source in the source category. The HAP air concentrations at
each nearby census block centroid located within 50 km of the facility
are a surrogate for the chronic inhalation exposure concentration for
all the people who reside in that census block. A distance of 50 km is
consistent with the limitations of Gaussian dispersion models,
including AERMOD.
    For each facility, we calculate the MIR as the cancer risk
associated with a continuous lifetime (24 hours per day, 7 days per
week, 52 weeks per year, 70 years) exposure to the maximum
concentration at the centroid of each inhabited census block. We
calculate individual cancer risk by multiplying the estimated lifetime
exposure to the ambient concentration of each HAP (in micrograms per
cubic meter ([mu]g/m\3\) by its unit risk estimate (URE). The URE is an
upper-bound estimate of an individual's incremental risk of contracting
cancer over a lifetime of exposure to a concentration of 1 microgram of
the pollutant per cubic meter of air. For residual risk assessments, we
generally use UREs from the EPA's Integrated Risk Information System
(IRIS). For carcinogenic pollutants without IRIS values, we look to
other reputable sources of cancer dose-response values, often using
California EPA (CalEPA) UREs, where available. In cases where new,
scientifically credible dose-response values have been developed in a
manner consistent with EPA guidelines and have undergone a peer review
process similar to that used by the EPA, we may use such dose-response
values in place of, or in addition to, other values, if appropriate.
The pollutant-specific dose-response values used to estimate health
risk are available at https://www.epa.gov/fera/dose-response-assessment-assessing-health-risks-associated-exposure-hazardous-air-pollutants.
    To estimate individual lifetime cancer risks associated with
exposure to HAP emissions from each facility in the source category, we
sum the risks for each of the carcinogenic HAP \12\ emitted by the
modeled facility. We estimate cancer risk at every census block within
50 km of every facility in the source category. The MIR is the highest
individual lifetime cancer risk estimated for any of those census
blocks. In addition to calculating the MIR, we estimate the
distribution of individual cancer risks for the source category by
summing the number of individuals within 50 km of the sources whose
estimated risk falls within a specified risk range. We also estimate
annual cancer incidence by multiplying the estimated lifetime cancer
risk at each census block by the number of people residing in that
block, summing results for all of the census blocks, and then dividing
this result by a 70-year lifetime.
---------------------------------------------------------------------------

    \12\ The EPA's 2005 Guidelines for Carcinogen Risk Assessment
classifies carcinogens as: ``carcinogenic to humans,'' ``likely to
be carcinogenic to humans,'' and ``suggestive evidence of
carcinogenic potential.'' These classifications also coincide with
the terms ``known carcinogen, probable carcinogen, and possible
carcinogen,'' respectively, which are the terms advocated in the
EPA's Guidelines for Carcinogen Risk Assessment, published in 1986
(51 FR 33992, September 24, 1986). In August 2000, the document,
Supplemental Guidance for Conducting Health Risk Assessment of
Chemical Mixtures (EPA/630/R-00/002), was published as a supplement
to the 1986 document. Copies of both documents can be obtained from
https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=20533&CFID=70315376&CFTOKEN=71597944. Summing
the risk of these individual compounds to obtain the cumulative
cancer risk is an approach that was recommended by the EPA's SAB in
their 2002 peer review of the EPA's National Air Toxics Assessment
(NATA) titled NATA--Evaluating the National-scale Air Toxics
Assessment 1996 Data--an SAB Advisory, available at https://nepis.epa.gov/Exe/ZyNET.exe/P100JOEY.TXT?ZyActionD=ZyDocument&Client=EPA&Index=2000+Thru+2005&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C00thru05%5CTxt%5C00000033%5CP100JOEY.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=hpfr&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=x&ZyPURL.
---------------------------------------------------------------------------

    To assess the risk of noncancer health effects from chronic
exposure to HAP, we calculate either an HQ or a target organ-specific
hazard index (TOSHI). We calculate an HQ when a single noncancer HAP is
emitted. Where more than one noncancer HAP is emitted, we sum the HQ
for each of the HAP that affects a common target organ or target organ
system to obtain a TOSHI. The HQ is the estimated exposure divided by
the chronic noncancer dose-response value, which is a value selected
from one of several sources. The preferred chronic noncancer dose-
response value is the EPA RfC, defined as ``an estimate (with
uncertainty spanning perhaps an order of magnitude) of a continuous
inhalation exposure to the human population (including sensitive
subgroups) that is likely to be without an appreciable risk of
deleterious effects during a lifetime'' (https://iaspub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&vocabName=IRIS%20Glossary). In cases where an RfC
from the EPA's IRIS is not available or where the EPA determines that
using a value other than the RfC is appropriate, the chronic noncancer
dose-response value can be a value from the following prioritized
sources, which define their dose-response values similarly to the EPA:
(1) the Agency for Toxic Substances and Disease Registry (ATSDR)
Minimum Risk Level (https://www.atsdr.cdc.gov/mrls/index.asp); (2) the
CalEPA Chronic Reference Exposure Level (REL) (https://oehha.ca.gov/air/crnr/notice-adoption-air-toxics-hot-spots-program-guidance-manual-preparation-health-risk-0); or (3) as noted above, a scientifically
credible dose-response value that has been developed in a manner
consistent with the EPA guidelines and has undergone a peer review
process similar to that

used by the EPA. The pollutant-specific dose-response values used to
estimate health risks are available at https://www.epa.gov/fera/dose-response-assessment-assessing-health-risks-associated-exposure-hazardous-air-pollutants.
c. Risk From Acute Exposure to HAP That May Cause Health Effects Other
Than Cancer
    For each HAP for which appropriate acute inhalation dose-response
values are available, the EPA also assesses the potential health risks
due to acute exposure. For these assessments, the EPA makes
conservative assumptions about emission rates, meteorology, and
exposure location. As part of our efforts to continually improve our
methodologies to evaluate the risks that HAP emitted from categories of
industrial sources pose to human health and the environment,\13\ we
revised our treatment of meteorological data to use reasonable worst-
case air dispersion conditions in our acute risk screening assessments
instead of worst-case air dispersion conditions. This revised treatment
of meteorological data and the supporting rationale are described in
more detail in Residual Risk Assessment for Coke Ovens: Pushing,
Quenching, and Battery Stacks Source Category in Support of the 2023
Risk and Technology Review Proposed Rule and in Appendix 5 of the
report: Technical Support Document for Acute Risk Screening Assessment.
This revised approach has been used in this proposed rule and in all
other RTR rulemakings proposed on or after June 3, 2019.
---------------------------------------------------------------------------

    \13\ See, e.g., U.S. EPA. Screening Methodologies to Support
Risk and Technology Reviews (RTR): A Case Study Analysis (Draft
Report, May 2017. https://www3.epa.gov/ttn/atw/rrisk/rtrpg.html).
---------------------------------------------------------------------------

    To assess the potential acute risk to the maximally exposed
individual, we use the peak hourly emission rate for each emission
point,\14\ reasonable worst-case air dispersion conditions (i.e., 99th
percentile), and the point of highest off-site exposure. Specifically,
we assume that peak emissions from the source category and reasonable
worst-case air dispersion conditions co-occur and that a person is
present at the point of maximum exposure.
---------------------------------------------------------------------------

    \14\ In the absence of hourly emission data, we develop
estimates of maximum hourly emission rates by multiplying the
average actual annual emissions rates by a factor (either a
category-specific factor or a default factor of 10) to account for
variability. This is documented in Residual Risk Assessment for Coke
Ovens: Pushing, Quenching, and Battery Stacks in Support of the 2023
Risk and Technology Review Proposed Rule and in Appendix 5 of the
report: Technical Support Document for Acute Risk Screening
Assessment. Both are available in the docket for this rulemaking.
---------------------------------------------------------------------------

    To characterize the potential health risks associated with
estimated acute inhalation exposures to a HAP, we generally use
multiple acute dose-response values, including acute RELs, acute
exposure guideline levels (AEGLs), and emergency response planning
guidelines (ERPG) for 1-hour exposure durations, if available, to
calculate acute HQs. The acute HQ is calculated by dividing the
estimated acute exposure concentration by the acute dose-response
value. For each HAP for which acute dose-response values are available,
the EPA calculates acute HQs.
    An acute REL is defined as ``the concentration level at or below
which no adverse health effects are anticipated for a specified
exposure duration.'' \15\ Acute RELs are based on the most sensitive,
relevant, adverse health effect reported in the peer-reviewed medical
and toxicological literature. They are designed to protect the most
sensitive individuals in the population through the inclusion of
margins of safety. Because margins of safety are incorporated to
address data gaps and uncertainties, exceeding the REL does not
automatically indicate an adverse health impact. AEGLs represent
threshold exposure limits for the general public and are applicable to
emergency exposures ranging from 10 minutes to 8 hours.\16\ They are
guideline levels for ``once-in-a-lifetime, short-term exposures to
airborne concentrations of acutely toxic, high-priority chemicals.''
Id. at 21. The AEGL-1 is specifically defined as ``the airborne
concentration (expressed as ppm (parts per million) or mg/m\3\
(milligrams per cubic meter)) of a substance above which it is
predicted that the general population, including susceptible
individuals, could experience notable discomfort, irritation, or
certain asymptomatic nonsensory effects. However, the effects are not
disabling and are transient and reversible upon cessation of
exposure.'' The document also notes that ``Airborne concentrations
below AEGL-1 represent exposure levels that can produce mild and
progressively increasing but transient and nondisabling odor, taste,
and sensory irritation or certain asymptomatic, nonsensory effects.''
Id. AEGL-2 are defined as ``the airborne concentration (expressed as
ppm or mg/m\3\) of a substance above which it is predicted that the
general population, including susceptible individuals, could experience
irreversible or other serious, long-lasting adverse health effects or
an impaired ability to escape.'' Id.
---------------------------------------------------------------------------

    \15\ CalEPA issues acute RELs as part of its Air Toxics Hot
Spots Program, and the 1-hour and 8-hour values are documented in
Air Toxics Hot Spots Program Risk Assessment Guidelines, Part I, The
Determination of Acute Reference Exposure Levels for Airborne
Toxicants, which is available at https://oehha.ca.gov/air/general-info/oehha-acute-8-hour-and-chronic-reference-exposure-level-rel-summary.
    \16\ National Academy of Sciences, 2001. Standing Operating
Procedures for Developing Acute Exposure Levels for Hazardous
Chemicals, page 2. Available at https://www.epa.gov/sites/production/files/2015-09/documents/sop_final_standing_operating_procedures_2001.pdf. Note that the
National Advisory Committee for Acute Exposure Guideline Levels for
Hazardous Substances ended in October 2011, but the AEGL program
continues to operate at the EPA and works with the National
Academies to publish final AEGLs (https://www.epa.gov/aegl).
---------------------------------------------------------------------------

    ERPGs are developed, by the American Industrial Hygiene Association
(AIHA), for emergency planning and are intended to be health-based
guideline concentrations for single exposures to chemicals. The ERPG-1
is the maximum airborne concentration, established by AIHI below which
it is believed that nearly all individuals could be exposed for up to 1
hour without experiencing other than mild transient adverse health
effects or without perceiving a clearly defined, objectionable odor.
Similarly, the ERPG-2 is the maximum airborne concentration,
established by AIHA, below which it is believed that nearly all
individuals could be exposed for up to 1 hour without experiencing or
developing irreversible or other serious health effects or symptoms
which could impair an individual's ability to take protective action.
    An acute REL for 1-hour exposure durations is typically lower than
its corresponding AEGL-1 and ERPG-1. Even though their definitions are
slightly different, AEGL-1s are often the same as the corresponding
ERPG-1s, and AEGL-2s are often equal to ERPG-2s. The maximum HQs from
our acute inhalation screening risk assessment typically result when we
use the acute REL for a HAP. In cases where the maximum acute HQ
exceeds 1, we also report the HQ based on the next highest acute dose-
response value (usually the AEGL-1 and/or the ERPG-1).
    For these source categories, a factor of 2 was applied to actual
emissions to calculate the acute emissions. Coke oven charging,
pushing, and quenching operations maintain largely consistent hour-to-
hour pushing rates because plants are constrained by oven capacity,
coking temperatures, coking times, and plant design/equipment. Coke
plants may have small deviations in short-term emission rates from
annual average emission rates. An analysis of hourly pushing records at
five coke plants showed that the hourly pushing rate

does not deviate significantly from the annual average pushing rate,
with multipliers ranging from 1.26 to 2.06.\17\ Acute levels of HAP
emissions from other coke emission sources are thought to mirror the
pushing emissions based on a reasonable expectation that those levels
would mirror the acute levels estimated for pushing operations;
therefore, an acute factor of two was used for all sources at coke
facilities. A further discussion of why this factor was chosen can be
found in the Data Memorandum,\4\ located in the docket for the rule. We
request comments on the validity of the assumption of two for an acute
factor.
---------------------------------------------------------------------------

    \17\ Personal communication (email). A.C. Dittenhoefer, Coke
Oven Environmental Task Force (COETF) of the American Coke and Coal
Chemicals Institute, with D.L. Jones, U.S. Environmental Protection
Agency, Office of Air Quality Planning and Standards, Research
Triangle Park, North Carolina. August 31, 2020.
---------------------------------------------------------------------------

    In our acute inhalation screening risk assessment, acute impacts
are deemed negligible for HAP for which acute HQs are less than or
equal to 1, and no further analysis is performed for these HAP. In
cases where an acute HQ from the screening step is greater than 1, we
assess the site-specific data to ensure that the acute HQ is at an off-
site location.
4. How do we conduct the multipathway exposure and risk screening
assessment?
    The EPA conducts a tiered screening assessment examining the
potential for significant human health risks due to exposures via
routes other than inhalation (i.e., ingestion). We first determine
whether any sources in the source categories emit any HAP known to be
persistent and bioaccumulative in the environment, as identified in the
EPA's Air Toxics Risk Assessment Library (see Volume 1, Appendix D, at
https://www.epa.gov/fera/risk-assessment-and-modeling-air-toxics-risk-assessment-reference-library).
    For the Coke Ovens: Pushing, Quenching, and Battery Stacks source
category, we identified PB-HAP emissions of arsenic, cadmium, dioxin,
lead, mercury and POMs (polycyclic organic matter), so we proceeded to
the next step of the evaluation. Except for lead, the human health risk
screening assessment for PB-HAP consists of three progressive tiers. In
a Tier 1 screening assessment, we determine whether the magnitude of
the facility-specific emissions of PB-HAP warrants further evaluation
to characterize human health risk through ingestion exposure. To
facilitate this step, we evaluate emissions against previously
developed screening threshold emission rates for several PB-HAP that
are based on a hypothetical upper-end screening exposure scenario
developed for use in conjunction with the EPA's Total Risk Integrated
Methodology. Fate, Transport, and Ecological Exposure (TRIM.FaTE)
model. The PB-HAP with screening threshold emission rates are arsenic
compounds, cadmium compounds, chlorinated dibenzodioxins and furans,
mercury compounds, and POM. Based on the EPA estimates of toxicity and
bioaccumulation potential, these pollutants represent a conservative
list for inclusion in multipathway risk assessments for RTR rules. (See
Volume 1, Appendix D at https://www.epa.gov/sites/production/files/2013-08/documents/volume_1_reflibrary.pdf.) In this assessment, we
compare the facility-specific emission rates of these PB-HAP to the
screening threshold emission rates for each PB-HAP to assess the
potential for significant human health risks via the ingestion pathway.
We call this application of the TRIM.FaTE model the Tier 1 screening
assessment. The ratio of a facility's actual emission rate to the Tier
1 screening threshold emission rate is a ``screening value.''
    We derive the Tier 1 screening threshold emission rates for these
PB-HAP (other than lead compounds) to correspond to a maximum excess
lifetime cancer risk of 1-in-1 million (i.e., for arsenic compounds,
polychlorinated dibenzodioxins and furans, and POM) or, for HAP that
cause noncancer health effects (i.e., cadmium compounds and mercury
compounds), a maximum HQ of 1. If the emission rate of any one PB-HAP
or combination of carcinogenic PB-HAP in the Tier 1 screening
assessment exceeds the Tier 1 screening threshold emission rate for any
facility (i.e., the screening value is greater than 1), we conduct a
second screening assessment, which we call the Tier 2 screening
assessment. The Tier 2 screening assessment separates the Tier 1
combined fisher and farmer exposure scenario into fisher, farmer, and
gardener scenarios that retain upper-bound ingestion rates.
    In the Tier 2 screening assessment, the location of each facility
that exceeds a Tier 1 screening threshold emission rate is used to
refine the assumptions associated with the Tier 1 fisher and farmer
exposure scenarios at that facility. A key assumption in the Tier 1
screening assessment is that a lake and/or farm is located near the
facility. As part of the Tier 2 screening assessment, we use a U.S.
Geological Survey (USGS) database to identify actual waterbodies within
50 km of each facility and assume the fisher only consumes fish from
lakes within that 50 km zone. We also examine the differences between
local meteorology near the facility and the meteorology used in the
Tier 1 screening assessment. We then adjust the previously-developed
Tier 1 screening threshold emission rates for each PB-HAP for each
facility based on an understanding of how exposure concentrations
estimated for the screening scenario change with the use of local
meteorology and the USGS lakes database.
    In the Tier 2 farmer scenario, we maintain an assumption that the
farm is located within 0.5 km of the facility and that the farmer
consumes meat, eggs, dairy, vegetables, and fruit produced near the
facility. We may further refine the Tier 2 screening analysis by
assessing a gardener scenario to characterize a range of exposures,
with the gardener scenario being more plausible in RTR evaluations.
Under the gardener scenario, we assume the gardener consumes home-
produced eggs, vegetables, and fruit products at the same ingestion
rate as the farmer. The Tier 2 screen continues to rely on the high-end
food intake assumptions that were applied in Tier 1 for local fish
(adult female angler at 99th percentile fish consumption) \18\ and
locally grown or raised foods (90th percentile consumption of locally
grown or raised foods for the farmer and gardener scenarios).\19\ If
PB-HAP emission rates do not result in a Tier 2 screening value greater
than 1, we consider those PB-HAP emissions to pose risks below a level
of concern. If the PB-HAP emission rates for a facility exceed the Tier
2 screening threshold emission rates, we may conduct a Tier 3 screening
assessment.
---------------------------------------------------------------------------

    \18\ Burger, J. 2002. Daily consumption of wild fish and game:
Exposures of high end recreationists. International Journal of
Environmental Health Research, 12:343-354.
    \19\ U.S. EPA. Exposure Factors Handbook 2011 Edition (Final).
U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/
052F, 2011.
---------------------------------------------------------------------------

    There are several analyses that can be included in a Tier 3
screening assessment, depending upon the extent of refinement
warranted, including validating that the lakes are fishable, locating
residential/garden locations for urban and/or rural settings,
considering plume-rise to estimate emissions lost above the mixing
layer, and considering hourly effects of meteorology and plume-rise on
chemical fate and transport (a time-series analysis). If necessary, the
EPA may further refine the screening assessment through a site-specific
assessment.

    In evaluating the potential multipathway risk from emissions of
lead compounds, rather than developing a screening threshold emission
rate, we compare maximum estimated chronic inhalation exposure
concentrations to the level of the current National Ambient Air Quality
Standard (NAAQS) for lead.\20\ Values below the level of the primary
(health-based) lead NAAQS are considered to have a low potential for
multipathway risk.
---------------------------------------------------------------------------

    \20\ In doing so, the EPA notes that the legal standard for a
primary NAAQS--that a standard is requisite to protect public health
and provide an adequate margin of safety (CAA section 109(b))--
differs from the CAA section 112(f) standard (requiring, among other
things, that the standard provide an ``ample margin of safety to
protect public health''). However, the primary lead NAAQS is a
reasonable measure of determining risk acceptability (i.e., the
first step of the Benzene NESHAP analysis) since it is designed to
protect the most susceptible group in the human population--
children, including children living near major lead emitting
sources. 73 FR 67002/3; 73 FR 67000/3; 73 FR 67005/1. In addition,
applying the level of the primary lead NAAQS at the risk
acceptability step is conservative since that primary lead NAAQS
reflects an adequate margin of safety.
---------------------------------------------------------------------------

    For further information on the multipathway assessment approach,
see the Residual Risk Assessment for the Coke Ovens: Pushing,
Quenching, and Battery Stacks Source Category in Support of the 2023
Risk and Technology Review Proposed Rule available in the docket for
this action.
5. How do we conduct the environmental risk screening assessment?
a. Adverse Environmental Effect, Environmental HAP, and Ecological
Benchmarks
    The EPA conducts a screening assessment to examine the potential
for an adverse environmental effect as required under section
112(f)(2)(A) of the CAA. Section 112(a)(7) of the CAA defines ``adverse
environmental effect'' as ``any significant and widespread adverse
effect, which may reasonably be anticipated, to wildlife, aquatic life,
or other natural resources, including adverse impacts on populations of
endangered or threatened species or significant degradation of
environmental quality over broad areas.''
    The EPA focuses on eight HAP, which are referred to as
``environmental HAP,'' in its screening assessment: six PB-HAP and two
acid gases. The PB-HAP included in the screening assessment are arsenic
compounds, cadmium compounds, dioxins/furans, POM, mercury (both
inorganic mercury and methyl mercury), and lead compounds. The acid
gases included in the screening assessment are hydrochloric acid (HCl)
and hydrogen fluoride (HF).
    The HAP that persist and bioaccumulate are of particular
environmental concern because they accumulate in the soil, sediment,
and water. The acid gases, HCl and HF, are included due to their well-
documented potential to cause direct damage to terrestrial plants. In
the environmental risk screening assessment, we evaluate the following
four exposure media: terrestrial soils, surface water bodies (includes
water-column and benthic sediments), fish consumed by wildlife, and
air. Within these four exposure media, we evaluate nine ecological
assessment endpoints, which are defined by the ecological entity and
its attributes. For PB-HAP (other than lead), both community-level and
population-level endpoints are included. For acid gases, the ecological
assessment evaluated is terrestrial plant communities.
    An ecological benchmark represents a concentration of HAP that has
been linked to a particular environmental effect level. For each
environmental HAP, we identified the available ecological benchmarks
for each assessment endpoint. We identified, where possible, ecological
benchmarks at the following effect levels: probable effect levels,
lowest-observed-adverse-effect level, and no-observed-adverse-effect
level. In cases where multiple effect levels were available for a
particular PB-HAP and assessment endpoint, we use all of the available
effect levels to help us to determine whether ecological risks exist
and, if so, whether the risks could be considered significant and
widespread.
    For further information on how the environmental risk screening
assessment was conducted, including a discussion of the risk metrics
used, how the environmental HAP were identified, and how the ecological
benchmarks were selected, see Appendix 9 of the Residual Risk
Assessment for the Coke Ovens: Pushing, Quenching, and Battery Stacks
Source Category in Support of the 2023 Risk and Technology Review
Proposed Rule available in the docket for this action.
b. Environmental Risk Screening Methodology
    For the environmental risk screening assessment, the EPA first
determined whether any facilities in the Coke Ovens: Pushing,
Quenching, and Battery Stacks source category emitted any of the
environmental HAP. For the Coke Ovens: Pushing, Quenching, and Battery
Stacks source category, we identified emissions of arsenic, cadmium,
dioxin, HCl, HF, lead, mercury (methyl mercury and divalent mercury),
and POMs. Because one or more of these environmental HAP are emitted by
at least one facility in the source category, we proceeded to the
second step of the evaluation for the source category.
c. PB-HAP Methodology
    The environmental screening assessment includes six PB-HAP, arsenic
compounds, cadmium compounds, dioxins/furans, POM, mercury (both
inorganic mercury and methyl mercury), and lead compounds. With the
exception of lead, the environmental risk screening assessment for PB-
HAP consists of three tiers. The first tier of the environmental risk
screening assessment uses the same health-protective conceptual model
that is used for the Tier 1 human health screening assessment.
TRIM.FaTE model simulations were used to back-calculate Tier 1
screening threshold emission rates. The screening threshold emission
rates represent the emission rate in tons of pollutant per year that
results in media concentrations at the facility that equal the relevant
ecological benchmark. To assess emissions from each facility in the
category, the reported emission rate for each PB-HAP was compared to
the Tier 1 screening threshold emission rate for that PB-HAP for each
assessment endpoint and effect level. If emissions from a facility do
not exceed the Tier 1 screening threshold emission rate, the facility
``passes'' the screening assessment, and, therefore, is not evaluated
further under the screening approach. If emissions from a facility
exceed the Tier 1 screening threshold emission rate, we evaluate the
facility further in Tier 2.
    In Tier 2 of the environmental screening assessment, the screening
threshold emission rates are adjusted to account for local meteorology
and the actual location of lakes in the vicinity of facilities that did
not pass the Tier 1 screening assessment. For soils, we evaluate the
average soil concentration for all soil parcels within a 7.5 km-radius
for each facility and PB-HAP. For the water, sediment, and fish tissue
concentrations, the highest value for each facility for each pollutant
is used. If emission concentrations from a facility do not exceed the
Tier 2 screening threshold emission rate, the facility ``passes'' the
screening assessment and typically is not evaluated further. If
emissions from a facility exceed the Tier 2 screening threshold
emission rate, we evaluate the facility further in Tier 3.
    As in the multipathway human health risk assessment, in Tier 3 of
the

environmental screening assessment, we examine the suitability of the
lakes around the facilities to support life and remove those that are
not suitable (e.g., lakes that have been filled in or are industrial
ponds), adjust emissions for plume-rise, and conduct hour-by-hour time-
series assessments. If these Tier 3 adjustments to the screening
threshold emission rates still indicate the potential for an adverse
environmental effect (i.e., facility emission rate exceeds the
screening threshold emission rate), we may elect to conduct a more
refined assessment using more site-specific information. If, after
additional refinement, the facility emission rate still exceeds the
screening threshold emission rate, the facility may have the potential
to cause an adverse environmental effect.
    To evaluate the potential for an adverse environmental effect from
lead, we compared the average modeled air concentrations (from HEM) of
lead around each facility in the source category to the level of the
secondary NAAQS for lead. The secondary lead NAAQS is a reasonable
means of evaluating environmental risk because it is set to provide
substantial protection against adverse welfare effects which can
include ``effects on soils, water, crops, vegetation, man-made
materials, animals, wildlife, weather, visibility and climate, damage
to and deterioration of property, and hazards to transportation, as
well as effects on economic values and on personal comfort and well-
being.''
d. Acid Gas Environmental Risk Methodology
    The environmental screening assessment for acid gases evaluates the
potential phytotoxicity and reduced productivity of plants due to
chronic exposure to HF and HCl. The environmental risk screening
methodology for acid gases is a single-tier screening assessment that
compares modeled ambient air concentrations (from AERMOD) to the
ecological benchmarks for each acid gas. To identify a potential
adverse environmental effect (as defined in section 112(a)(7) of the
CAA) from emissions of HF and HCl, we evaluate the following metrics:
the size of the modeled area around each facility that exceeds the
ecological benchmark for each acid gas, in acres and square kilometers;
the percentage of the modeled area around each facility that exceeds
the ecological benchmark for each acid gas; and the area-weighted
average screening value around each facility (calculated by dividing
the area-weighted average concentration over the 50 km-modeling domain
by the ecological benchmark for each acid gas). For further information
on the environmental screening assessment approach, see Appendix 9 of
the Residual Risk Assessment for the Coke Ovens: Pushing, Quenching,
and Battery Stacks Source Category in Support of the 2023 Risk and
Technology Review Proposed Rule available in the docket for this
action.
6. How do we conduct facility-wide assessments?
    To put the source category risks in context, we typically examine
the risks from the entire ``facility,'' where the facility includes all
HAP-emitting operations within a contiguous area and under common
control. In other words, we examine the HAP emissions not only from the
source category emission points of interest, but also emissions of HAP
from all other emission sources at the facility for which we have data.
For this source category, we conducted the facility-wide assessment
using a dataset compiled from CAA section 114 request data from 2016
and 2022, as well as from the 2017 NEI. The source category data were
evaluated as described in section II.C. of this preamble: What data
collection activities were conducted to support this action? Once a
quality-assured source category dataset was available, the facility-
wide file was then used to analyze risks due to the inhalation of HAP
that are emitted ``facility-wide'' for the populations residing within
50 km of each facility, consistent with the methods used for the source
category analysis described above. For these facility-wide risk
analyses, the modeled source category risks were compared to the
facility-wide risks to determine the portion of the facility-wide risks
that could be attributed to the source category addressed in this risk
assessment. We also specifically examined the facility that was
associated with the highest estimate of risk and determined the
percentage of that risk attributable to the source category of
interest. The Residual Risk Assessment for the Coke Ovens: Pushing,
Quenching, and Battery Stack Source Category in Support of the 2023
Risk and Technology Review Proposed Rule, available through the docket
for this action, provides the methodology and results of the facility-
wide analyses, including all facility-wide risks and the percentage of
source category contribution to facility-wide risks.
7. How do we conduct community-based risk assessments?
    In addition to the source category and facility-wide risk
assessments, we also assessed the combined inhalation cancer risk from
all local stationary sources of HAP for which we have emissions data.
Specifically, we combined the modeled impacts from the facility-wide
assessment (which includes category and non-category sources) with
other nearby stationary point source model results. The facility-wide
emissions used in this assessment are discussed in section II.C. of
this preamble. For the other nearby point sources, we used AERMOD model
results with emissions based primarily on the 2018 NEI. After combining
these model results, we assessed cancer risks due to the inhalation of
all HAP emitted by point sources for the populations residing within 10
km of coke oven facilities. In the community-based risk assessment, the
modeled source category and facility-wide cancer risks were compared to
the cancer risks from other nearby point sources to determine the
portion of the risks that could be attributed to the source category
addressed in this proposal. The document titled The Residual Risk
Assessment for the Coke Ovens: Pushing, Quenching, and Battery Stack
Source Category in Support of the 2023 Risk and Technology Review
Proposed Rule, which is available in the docket for this rulemaking,
provides the methodology and results of the community-based risk
analyses.
8. How do we consider uncertainties in risk assessment?
    Uncertainty and the potential for bias are inherent in all risk
assessments, including those performed for this proposal. Although
uncertainty exists, we believe that our approach, which used
conservative tools and assumptions, ensures that our decisions are
health and environmentally protective. A brief discussion of the
uncertainties in the RTR emissions dataset, dispersion modeling,
inhalation exposure estimates, and dose-response relationships follows
below. Also included are those uncertainties specific to our acute
screening assessments, multipathway screening assessments, and our
environmental risk screening assessments. A more thorough discussion of
these uncertainties is included in the Residual Risk Assessment for the
Coke Ovens: Pushing, Quenching, and Battery Stacks Source Category in
Support of the 2023 Risk and Technology Review Proposed Rule available
in the docket for this action.

a. Uncertainties in the RTR Emissions Dataset
    Although the development of the RTR emissions dataset involved
quality assurance/quality control processes, the accuracy of emissions
values will vary depending on the source of the data, the degree to
which data are incomplete or missing, the degree to which assumptions
made to complete the datasets are accurate, errors in emission
estimates, and other factors. The emission estimates considered in this
analysis generally are annual totals for certain years, and they do not
reflect short-term fluctuations during the course of a year or
variations from year to year. The estimates of peak hourly emission
rates for the acute effects screening assessment were based on an
emission adjustment factor applied to the average annual hourly
emission rates, which are intended to account for emission fluctuations
due to normal facility operations.
b. Uncertainties in Dispersion Modeling
    We recognize there is uncertainty in ambient concentration
estimates associated with any model, including the EPA's recommended
regulatory dispersion model, AERMOD. In using a model to estimate
ambient pollutant concentrations, the user chooses certain options to
apply. For RTR assessments, we select some model options that have the
potential to overestimate ambient air concentrations (e.g., not
including plume depletion or pollutant transformation). We select other
model options that have the potential to underestimate ambient impacts
(e.g., not including building downwash). Other options that we select
have the potential to either under- or overestimate ambient levels
(e.g., meteorology and receptor locations). On balance, considering the
directional nature of the uncertainties commonly present in ambient
concentrations estimated by dispersion models, the approach we apply in
the RTR assessments should yield unbiased estimates of ambient HAP
concentrations. We also note that the selection of meteorology dataset
location could have an impact on the risk estimates. As we continue to
update and expand our library of meteorological station data used in
our risk assessments, we expect to reduce this variability.
c. Uncertainties in Inhalation Exposure Assessment
    Although every effort is made to identify all of the relevant
facilities and emission points, as well as to develop accurate
estimates of the annual emission rates for all relevant HAP, the
uncertainties in our emission inventory likely dominate the
uncertainties in the exposure assessment. Some uncertainties in our
exposure assessment include human mobility, using the centroid of each
census block, assuming lifetime exposure, and assuming only outdoor
exposures. For most of these factors, there is neither an under nor
overestimate when looking at the maximum individual risk or the
incidence, but the shape of the distribution of risks may be affected.
With respect to outdoor exposures, actual exposures may not be as high
if people spend time indoors, especially for very reactive pollutants
or larger particles. For all factors, we reduce uncertainty when
possible. For example, with respect to census-block centroids, we
analyze large blocks using aerial imagery and adjust locations of the
block centroids to better represent the population in the blocks. We
also add additional receptor locations where the population of a block
is not well represented by a single location.
d. Uncertainties in Dose-Response Relationships
    There are uncertainties inherent in the development of the dose-
response values used in our risk assessments for cancer effects from
chronic exposures and noncancer effects from both chronic and acute