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

Federal RegisterAug 16, 2023

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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: a-and-r-docket@epa.gov.

Include Docket ID Nos. EPA-HQ-OAR-2002-0085 or EPA-HQ-OAR-2003-0051 in the subject line of the message.

•

Fax:

(202) 566-9744. 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: (919) 541-5251; email address:

jones.donnalee@epa.gov.

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: (919) 541-2766; email address:

moeller.michael@epa.gov.

SUPPLEMENTARY INFORMATION:

Participation in virtual public hearing.

To request a virtual public hearing, contact the public hearing team at (888) 372-8699 or by email at

SPPDpublichearing@epa.gov.

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

or contact the public hearing team at (888) 372-8699 or by email at

SPPDpublichearing@epa.gov.

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

jones.donnalee@epa.gov.

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

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

SPPDpublichearing@epa.gov

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

oaqpscbi@epa.gov,

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

oaqpscbi@epa.gov

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

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

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

µg/m

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

Item

Inhalation

cancer risk

MIR in

1 million

Population cancer risk

Estimated annual cancer incidence

(cases per year)

≥ 1-in-1

million

Coke Ovens Pushing, Quenching, and Battery Stacks Source Category

0.02

2,900

Post Control Risks for the Coke Ovens Pushing, Quenching, and Battery Stacks Source Category

0.02

390

Whole Facility

0.2

2.7M

Post Control Whole Facility Risks

0.2

2.7M

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

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 PM

2.5

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

Coke Ovens: Pushing, Quenching, and Battery Stacks

40 CFR part 63, subpart CCCCC

331110 Iron and Steel Mills and Ferroalloy Manufacturing.

Coke Oven Batteries

40 CFR part 63, subpart L

324199 All Other Petroleum and Coal Products Manufacturing.

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

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)

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.

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)

EPA,

529 F.3d 1077, 1084 (D.C. Cir. 2008).

Association of Battery Recyclers, Inc.

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)

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 (°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

ByP

Yes.

Bluestone

Birmingham

ByP

No.

Cleveland-Cliffs

Middletown

ByP

No.

Cleveland-Cliffs

Follansbee

ByP

No.

Cleveland-Cliffs

Burns Harbor

ByP

Yes.

Cleveland-Cliffs

Monessen

ByP

Yes.

Cleveland-Cliffs

Warren

ByP

Yes.

EES Coke Battery

DTE Vantage

Detroit

ByP

Yes.

Indiana Harbor Coke

SunCoke Energy

East Chicago

HNR

Yes.

Haverhill Coke

SunCoke Energy

Franklin Furnace

HNR

Yes.

Gateway Coke

SunCoke Energy

Granite City

HNR

Yes.

Middletown Coke

SunCoke Energy

Middletown

HNR

Yes.

Jewell Coke

SunCoke Energy

Vansant

HNR

Yes.

US Steel Clairton

United States Steel

Clairton

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.

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.

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 (SO

) 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

Emission source

Limits by track

and effective date

MACT

July 14, 2005

(residual risk)

LAER

January

2010

Residual

Risk

Percent leaking lids

0.4

TBD

Percent leaking offtakes

2.5

TBD.

Charging (log

) s/charge

TBD.

Percent leaking doors—Tall

4.0

TBD.

Percent leaking doors—All other

3.3

TBD.

Percent leaking doors—Foundry

3.3

4.0

TBD.

The tracks were established in the 1993 NESHAP for Coke Oven Batteries in a tiered approach (58 FR 57898).

Established in the 2005 RTR final rule for Coke Oven Batteries (70 FR 19992). Only applies to one current ByP facility, which is idle.

TBD = to be determined, as specified in section 171 of the CAA.

Log = the logarithmic average of the observations of multiple charges (as opposed to an arithmetic average).

s/charge = seconds of visible emissions per charge of coal into the oven.

Tall = doors 20 feet (six meters) or more in height (Coke Oven Batteries).

All other = all blast furnace coke oven doors that are not tall,

i.e.,

doors less than 20 feet (six meters).

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,

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.

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,

hereafter referred to as the “Data Memorandum,” available in the docket for this proposed rulemaking.

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.

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.

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.”

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

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;

and described in the SAB review report issued in 2010. They are also consistent with the key recommendations contained in that report.

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).

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,

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,

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

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).

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.

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.

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

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.

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).

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 (μg/m

) 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

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.

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,

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.

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,

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.

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.”

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.

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

(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

) 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.

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.

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.

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,

located in the docket for the rule. We request comments on the validity of the assumption of two for an acute factor.

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)

and locally grown or raised foods (90th percentile consumption of locally grown or raised foods for the farmer and gardener scenarios).

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.

Burger, J. 2002.

Daily consumption of wild fish and game: Exposures of high end recreationists. International Journal of Environmental Health Research,

12:343-354.

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.

Values below the level of the primary (health-based) lead NAAQS are considered to have a low potential for multipathway risk.

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 exposures. Some uncertainties are generally expressed quantitatively, and others are generally expressed in qualitative terms. We note, as a preface to this discussion, a point on dose-response uncertainty that is stated in the EPA's

2005 Guidelines for Carcinogen Risk Assessment;

namely, that “the primary goal of EPA actions is protection of human health; accordingly, as an Agency policy, risk assessment procedures, including default options that are used in the absence of scientific data to the contrary, should be health protective” (the EPA's

2005 Guidelines for Carcinogen Risk Assessment,

page 1-7). This is the approach followed here as summarized in the next paragraphs.

Cancer UREs used in our risk assessments are those that have been developed to generally provide an upper bound estimate of risk.

That is, they represent a “plausible upper limit to the true value of a quantity” (although this is usually not a true statistical confidence limit). In some circumstances, the true risk could be as low as zero; however, in other circumstances the risk could be greater.

Chronic noncancer RfC and reference dose (RfD) values represent chronic exposure levels that are intended to be health-protective levels. To derive dose-response values that are intended to be “without appreciable risk,” the methodology relies upon an uncertainty factor (UF) approach,

which considers uncertainty, variability, and gaps in the available data. The UFs are applied to derive dose-response values that are intended to protect against appreciable risk of deleterious effects.

IRIS glossary (

https://ofmpub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&glossaryName=IRIS%20Glossary

An exception to this is the URE for benzene, which is considered to cover a range of values, each end of which is considered to be equally plausible, and which is based on maximum likelihood estimates.

See

A Review of the Reference Dose and Reference Concentration Processes,

U.S. EPA, December 2002, and

Methods for Derivation of Inhalation Reference Concentrations and Application of Inhalation Dosimetry,

U.S. EPA, 1994.

Many of the UFs used to account for variability and uncertainty in the development of acute dose-response values are quite similar to those developed for chronic durations. Additional adjustments are often applied to account for uncertainty in extrapolation from observations at one exposure duration (

e.g.,

4 hours) to derive an acute dose-response value at another exposure duration (

e.g.,

1 hour). Not all acute dose-response values are developed for the same purpose, and care must be taken when interpreting the results of an acute assessment of human health effects relative to the dose-response value or values being exceeded. Where relevant to the estimated exposures, the lack of acute dose-response values at different levels of severity should be factored into the risk characterization as potential uncertainties.

Uncertainty also exists in the selection of ecological benchmarks for the environmental risk screening assessment. We established a hierarchy of preferred benchmark sources to allow selection of benchmarks for each environmental HAP at each ecological assessment endpoint. We searched for benchmarks for three effect levels (

i.e.,

no-effects level, threshold-effect level, and probable effect level), but not all combinations of ecological assessment/environmental HAP had benchmarks for all three effect levels. Where multiple effect levels were available for a particular HAP and assessment endpoint, we used all of the available effect levels to help us determine whether risk exists and whether the risk

could be considered significant and widespread.

Although we make every effort to identify appropriate human health effect dose-response values for all pollutants emitted by the sources in this risk assessment, some HAP emitted by the source category are lacking dose-response assessments. Accordingly, these pollutants cannot be included in the quantitative risk assessment, which could result in quantitative estimates understating HAP risk. To help to alleviate this potential underestimate, where we conclude similarity with a HAP for which a dose-response value is available, we use that value as a surrogate for the assessment of the HAP for which no value is available. To the extent use of surrogates indicates appreciable risk, we may identify a need to increase priority for an IRIS assessment for that substance. We additionally note that, generally speaking, HAP of greatest concern due to environmental exposures and hazard are those for which dose-response assessments have been performed, reducing the likelihood of understating risk. Further, HAP not included in the quantitative assessment are assessed qualitatively and considered in the risk characterization that informs the risk management decisions, including consideration of HAP reductions achieved by various control options.

For a group of compounds that are unspeciated (

e.g.,

glycol ethers), we conservatively use the most protective dose-response value of an individual compound in that group to estimate risk. Similarly, for an individual compound in a group (

e.g.,

ethylene glycol diethyl ether) that does not have a specified dose-response value, we also apply the most protective dose-response value from the other compounds in the group to estimate risk.

e. Uncertainties in Acute Inhalation Screening Assessments

In addition to the uncertainties highlighted above, there are several factors specific to the acute exposure assessment that the EPA conducts as part of the risk review under section 112 of the CAA. The accuracy of an acute inhalation exposure assessment depends on the simultaneous occurrence of independent factors that may vary greatly, such as hourly emissions rates, meteorology, and the presence of a person. In the acute screening assessment that we conduct under the RTR program, we assume that peak emissions from the source category and reasonable worst-case air dispersion conditions (

i.e.,

99th percentile) co-occur. We then include the additional assumption that a person is located at this point at the same time. Together, these assumptions represent a reasonable worst-case actual exposure scenario. In most cases, it is unlikely that a person would be located at the point of maximum exposure during the time when peak emissions and reasonable worst-case air dispersion conditions occur simultaneously.

f. Uncertainties in the Multipathway and Environmental Risk Screening Assessments

For each source category, we generally rely on site-specific levels of PB-HAP or environmental HAP emissions to determine whether a refined assessment of the impacts from multipathway exposures is necessary or whether it is necessary to perform an environmental screening assessment. This determination is based on the results of a three-tiered screening assessment that relies on the outputs from models—TRIM.FaTE and AERMOD—that estimate environmental pollutant concentrations and human exposures for five PB-HAP (dioxins, POM, mercury, cadmium, and arsenic) and two acid gases (HF and HCl). For lead, we use AERMOD to determine ambient air concentrations, which are then compared to the secondary NAAQS standard for lead. Two important types of uncertainty associated with the use of these models in RTR risk assessments and inherent to any assessment that relies on environmental modeling are model uncertainty and input uncertainty.

In the context of this discussion, the term “uncertainty” as it pertains to exposure and risk encompasses both

variability

in the range of expected inputs and screening results due to existing spatial, temporal, and other factors, as well as

uncertainty

in being able to accurately estimate the true result.

Model uncertainty concerns whether the model adequately represents the actual processes (

e.g.,

movement and accumulation) that might occur in the environment. For example, does the model adequately describe the movement of a pollutant through the soil? This type of uncertainty is difficult to quantify. However, based on feedback received from previous EPA SAB reviews and other reviews, we are confident that the models used in the screening assessments are appropriate and state-of-the-art for the multipathway and environmental screening risk assessments conducted in support of RTRs.

Input uncertainty is concerned with how accurately the models have been configured and parameterized for the assessment at hand. For Tier 1 of the multipathway and environmental screening assessments, we configured the models to avoid underestimating exposure and risk. This was accomplished by selecting upper-end values from nationally representative datasets for the more influential parameters in the environmental model, including selection and spatial configuration of the area of interest, lake location and size, meteorology, surface water, soil characteristics, and structure of the aquatic food web. We also assume an ingestion exposure scenario and values for human exposure factors that represent reasonable maximum exposures.

In Tier 2 of the multipathway and environmental screening assessments, we refine the model inputs to account for meteorological patterns in the vicinity of the facility versus using upper-end national values, and we identify the actual location of lakes near the facility rather than the default lake location that we apply in Tier 1. By refining the screening approach in Tier 2 to account for local geographical and meteorological data, we decrease the likelihood that concentrations in environmental media are overestimated, thereby increasing the usefulness of the screening assessment. In Tier 3 of the screening assessments, we refine the model inputs again to account for hour-by-hour plume-rise and the height of the mixing layer. We can also use those hour-by-hour meteorological data in a TRIM.FaTE run using the screening configuration corresponding to the lake location. These refinements produce a more accurate estimate of chemical concentrations in the media of interest, thereby reducing the uncertainty with those estimates. The assumptions and the associated uncertainties regarding the selected ingestion exposure scenario are the same for all three tiers.

For the environmental screening assessment for acid gases, we employ a single-tiered approach. We use the modeled air concentrations and compare those with ecological benchmarks.

For all tiers of the multipathway and environmental screening assessments, our approach to addressing model input uncertainty is generally cautious. We choose model inputs from the upper end of the range of possible values for the influential parameters used in the models, and we assume that the exposed individual exhibits ingestion behavior that would lead to a high total exposure. This approach reduces the likelihood of not identifying high risks for adverse impacts.

Despite the uncertainties, when individual pollutants or facilities do not

exceed screening threshold emission rates (

i.e.,

screen out), we are confident that the potential for adverse multipathway impacts on human health is very low. On the other hand, when individual pollutants or facilities do exceed screening threshold emission rates, it does not mean that impacts are significant, only that we cannot rule out that possibility and that a refined assessment for the site might be necessary to obtain a more accurate risk characterization for the source category.

The EPA evaluates the following HAP in the multipathway and/or environmental risk screening assessments, where applicable: arsenic, cadmium, dioxins/furans, lead, mercury (both inorganic and methyl mercury), POM, HCl, and HF. These HAP represent pollutants that can cause adverse impacts either through direct exposure to HAP in the air or through exposure to HAP that are deposited from the air onto soils and surface waters and then through the environment into the food web. These HAP represent those HAP for which we can conduct a meaningful multipathway or environmental screening risk assessment. For other HAP not included in our screening assessments, the model has not been parameterized such that it can be used for that purpose. In some cases, depending on the HAP, we may not have appropriate multipathway models that allow us to predict the concentration of that pollutant. The EPA acknowledges that other HAP beyond these that we are evaluating may have the potential to cause adverse effects and, therefore, the EPA may evaluate other relevant HAP in the future, as modeling science and resources allow.

IV. Analytical Results and Proposed Decisions

A. What actions are we taking pursuant to CAA sections 112(d)(2) and 112(d)(3)?

We are proposing the following pursuant to CAA sections 112(d)(2) and (3):

MACT standards for acid gases, hydrogen cyanide (HCN), mercury, and polycyclic aromatic hydrocarbons (PAH) from pushing operations for existing and new sources; MACT standards for acid gases, HCN, mercury, and PM (as a surrogate for nonmercury HAP metals

) from battery stacks for existing and new sources; and MACT standards for acid gases, mercury, PAH, and PM (as a surrogate for nonmercury HAP metals) from HNR HRSG control device main stacks for existing and new sources.

The EPA not only has authority under CAA sections 112(d)(2) and (3) to set MACT standards for previously unregulated HAP emissions at any time, but is required to address any previously unregulated HAP emissions as part of its periodic review of MACT standards under CAA section 112(d)(6).

LEAN

EPA,

955 F3d at 1091-1099.

Nonmercury HAP metals include the following compounds: antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, nickel, and selenium.

To determine the proposed MACT standards, we first calculated the MACT floor limits. The MACT floor limits were calculated by ranking the data for each emission point per HAP and determining the top 5 sources with emissions information, as per CAA sections 112(d)(2) and (3) for existing sources and the best performing source for new sources. These sources are referred to as the “MACT floor pool.” However, for two of the emissions points, ByP battery combustion and ByP and HNR pushing, we only had data from four facilities, so the MACT floor limits were based on data from the four facilities (except for mercury for pushing, we had data from five facilities); and for two other point sources, HNR Main stack and HNR bypass/waste stacks, we only had data from two facilities, so the MACT floor was based on data from the two facilities for these two emissions points.

The existing and new source MACT floor pool datasets were evaluated statistically to determine the distributions for both existing and new sources, by process type and by HAP. After determining the type of data distribution for the dataset, the upper predictive limit (UPL) was calculated using the corresponding equation for the distribution for that dataset and groupings of emission points. The UPL represents the value which one can expect the mean of a specified number of future observations (

e.g.,

3-run average) to fall below for the specified level of confidence (99 percent), based upon the results from the same population. The UPL approach encompasses all the data point-to-data point variability in the collected data, as derived from the dataset to which it is applied. The UPL was then compared to 3 times the representative detection limit (RDL) to ensure that data measurement variability is addressed and the higher value used as the MACT limit. The EPA also considered BTF options for each of the HAP emitted from pushing operations, battery stacks and HNR HRSG control device main stacks for existing and new sources. The EPA did not identify any cost-effective BTF options for HAP from these three sources; therefore, the EPA is proposing MACT floor limits for the HAP from pushing, battery stacks and HNR HRSG control device main stacks. For details on the MACT floor limits and BTF options see the memorandum titled

Maximum Achievable Control Technology (MACT) Standard Calculations, MACT Cost Impacts, and Beyond-the-Floor Cost Impacts for Coke Ovens Facilities under 40 CFR part 63, subpart CCCCC

(hereafter referred to as the “MACT/BTF Memorandum”), located in the docket for the proposed rule (EPA-HQ-OAR-2002-0085). The results and proposed decisions based on the analyses performed pursuant to CAA sections 112(d)(2) and (3) are presented in Table 5.

Maximum Achievable Control Technology Standard Calculations, Cost Impacts, and Beyond-the-Floor Cost Impacts for Coke Ovens Facilities under 40 CFR part 63, subpart CCCCC.

D. L. Jones, U.S. Environmental Protection Agency, and G. Raymond, RTI International. U.S. Environmental Protection Agency, Research Triangle Park, North Carolina. May 1, 2023. Docket ID No. EPA-HQ-OAR-2002-0085.

Table 5—Proposed MACT Standards for Unregulated HAP or Sources Developed Under CAA Section 112(

)(2) and (

)(3) for the NESHAP for Coke Ovens: Pushing, Quenching, Battery Stacks

[Subpart CCCCC]

Source or process

Pollutant

Type of affected source

(new or existing)

Existing

New

Pushing

acid gases

0.0052 lb/ton coke [UPL]

5.1E-04 lb/ton coke [UPL].

HCN

0.0011 lb/ton coke [UPL]

3.8E-05 lb/ton coke [UPL].

mercury

8.9E-07 lb/ton coke [UPL]

3.4E-07 lb mercury/ton coke [3xRDL].

PAH

3.4E-04 lb/ton coke [UPL]

1.4E-05 lb/ton coke [UPL].

Battery Stack

acid gases

0.083 lb/ton coke [UPL]

0.013 lb/ton coke [UPL].

HCN

0.0039 lb/ton coke [UPL]

7.4E-04 lb/ton coke [UPL].

mercury

5.8E-05 lb/ton coke [UPL]

7.1E-06 lb/ton coke [UPL].

0.10 PM gr/dscf [UPL]

0.014 gr/dscf [UPL].

HNR HRSG Control Device Main Stack

acid gases

0.038 gr/dscf [UPL]

0.0029 gr/dscf [UPL].

mercury

2.4E-06 gr/dscf [UPL]

1.5E-06 gr/dscf [UPL].

PAH

4.7E-07 gr/dscf [UPL]

3.7E-07 gr/dscf [UPL].

0.0065 gr/dscf [UPL]

7.5E-04 gr/dscf [UPL].

Note:

gr/dscf = grains per dry standard cubic feet. RDL = representative detection level. UPL = upper prediction limit.

For HNR

bypass/waste heat stacks, there is one HNR facility without HRSGs that sends COE directly to the atmosphere via waste heat stacks, 24 hours per day, 7 days per week. The other four heat recovery facilities utilize HRSGs most of the time (

i.e.,

process COE through the HRSG units) but send COE via ductwork to a bypass stack periodically to conduct maintenance on the HRSGs or because of other operational issues. All four heat recovery facilities with HRSGs have limits in their permits prepared under CAA title V requirements that limit the number of hours per year that they are allowed to use the bypass stacks. We are proposing to establish two subcategories with regard to the HNR bypass/waste stacks based on whether or not they process COE through an HRSG, as follows: (1) HNR facilities that have HRSGs; and (2) HNR facilities that do not have HRSGs. We only received CAA section 114 request test data (in 2016 and 2022) for bypass/waste stacks from two HNR facilities that have HRSGs (SunCoke's Granite City, Illinois, and Franklin Furnace, Ohio facilities). We did not receive bypass/waste stacks test data from the one HNR facility without HRSGs (SunCoke's Vansant, Virginia) nor for bypass/waste stacks at the other two HNR facilities with HRSGs (SunCoke's East Chicago, Indiana, and Middletown, Ohio, facilities). However, we concluded that the COE data from SunCoke's Granite City, Illinois, and SunCoke Franklin Furnace, Ohio, facilities (in units of gr/dscf by individual HAP tested) are representative of emissions from bypass/waste heat stacks for all 5 HNR facilities (including SunCoke's Vansant, Virginia, facility) due to the nearly identical conditions in the ovens at all the HNR facilities. The MACT floor limit, which is determined from the average of the lowest-emitting top 5 facilities, as stated in CAA section 112(d)(2), is therefore equal to the average emissions from SunCoke's Granite City, Illinois, and SunCoke Franklin Furnace, Ohio, facilities, where the COE from bypass/waste heat stacks are reported as the individual HAP emissions able to be tested with EPA test methods (in units of gr/dscf).

PM as a surrogate for HAP metals.

To determine whether or not more stringent MACT limits should be proposed as BTF standards for the two subcategories described above, we initially evaluated potential additional control options to lower the MACT limits for five HAP (referred to as “BTF Approach 1”) as follows: activated carbon injection (ACI) with 95 percent control efficiency for mercury; wet alkaline scrubber (WAS) with 95 percent control efficiency for PM as a surrogate for nonmercury HAP metals;

WAS with 99.9 percent control efficiency for acid gases (HCl and HF); regenerative thermal oxidizer (RTO) with 98 percent control efficiency for PAH; and RTO with 98 percent control efficiency for formaldehyde.

Next, we evaluated the BTF costs to control two HAP (mercury and nonmercury HAP metals) (referred to as “BTF Approach 2”) as follows: a baghouse with 99.9 percent control efficiency for PM as a surrogate for HAP metals; and ACI with 90 percent control efficiency for mercury. Table 6 shows the estimated capital and annualized costs, emission reductions, and cost effectiveness of the BTF controls for mercury, PM, acid gases, PAH, and formaldehyde at all five HNR facilities for BTF Approach 1. Table 6 shows the estimated capital and annualized costs, emission reductions, and cost-effectiveness of the BTF controls for mercury and PM (as a surrogate for nonmercury HAP metals) for BTF Approach 2.

Table 6—Comparison of Estimated Costs of Controls and Emission Reductions for Potential BTF MACT Standards for HNR Coke Facilities for Mercury and Nonmercury Metals for B/W Stacks Under BTF Approaches 1 and 2

Cost item

Approach 1

HNR facilities

with HRSGs

(includes 4

facilities)

HNR facilities

without HRSGs

(includes one

facility)

Approach 2

HNR facilities

with HRSGs

(includes 4

facilities)

HNR facilities

without HRSGs

(includes one

facility)

Capital Cost

Ductwork

$1,249K

$540K

$1,249K

$540K

ACI

$1,299K

$314K

$1,299K

$314K

n/a

$30M

$6.6M

WAS

$225M

$54M

n/a

RTO

$150M

$36M

n/a

Total Capital Cost

$378M

$91M

$33M

$7.5M

Annual Cost

Ductwork

$315K

$426K

$315K

$426K

ACI

$6.7M

$1.6M

$6.7M

$1.6M

n/a

$5.7M

$2.6M

WAS

$32M

$7.7M

n/a

RTO

$57M

$13M

n/a

Total Annual Cost

$95M

$22M

$13M

$4.7M

Uncontrolled Emissions (ton/yr, unless otherwise indicated)

Mercury (lbs/yr)

160

Nonmercury metal HAP

1.5

4.0

1.5

4.0

Acid Gases

360

956

n/a

PAH

0.0034

0.0091

n/a

Formaldehyde

0.28

0.74

n/a

Emission Reductions (ton/yr, unless otherwise indicated)

Mercury w/ACI (lb/yr) [CE%

]

57 [95%]

152 [95%]

54 [90%]

144 [90%]

Nonmercury Metal HAP w/BH [CE%]

n/a

1.5 [99.9%]

4.0 [99.9%]

Nonmercury Metal HAP w/WAS [CE%]

1.4 [95%]

3.8 [95%]

n/a

Acid Gases w/WAS [CE%]

359 [99.9%]

955 [99.9%]

n/a

PAH w/RTO [CE%]

0.0034 [98%]

0.0089 [98%]

n/a

Formaldehyde w/RTO [CE%]

0.27 [98%]

0.72 [98%]

n/a

Pollutant Cost Effectiveness ($/ton, unless otherwise indicated)

Mercury w/ACI ($/lb)

$117K

$11K

$123K

$11K

Nonmercury Metal HAP w/BH

n/a

$4.0M

$756K

Nonmercury Metal HAP w/WAS

$22M

$2.0M

n/a

Acid Gases w/WAS

$88K

$8.1K

n/a

PAH w/RTO

$17B

$1.4B

n/a

Formaldehyde w/RTO

$209M

$18M

n/a

Acid gases = HCl and HF; activated carbon injection = ACI; control efficiency = CE; baghouse = BH; not applicable to Approach 2 = n/a; regenerative thermal oxidizer = RTO; wet alkaline scrubber = WAS.

The COE from bypass/waste heat stacks are broken down into the individual HAP that are able to be tested with EPA test methods. Once the COE pass through control devices, the emissions are no longer considered COE.

Typically, ACI achieves about 90 percent mercury control, which is reflected in Approach 2. For Approach 1, the facility also would need to install a WAS for acid gas control. Because there is a small amount of Hg control from the WAS, incorporating the WAS control with the ACI control results in an estimated overall Hg of 95 percent.

Based on consideration of the estimated capital costs, annualized costs, reductions and cost effectiveness of the two approaches described above, we are proposing BTF emissions limits for the individual COE HAP, as nonmercury metals and mercury from B/W stacks, consistent with BTF Approach 2 for the subcategory that includes HNR facilities without HRSGs, which includes one facility (Vansant). We are proposing this option because we estimate that BTF Approach 2 achieves similar reductions of mercury. Mercury reduction under Approach 1 is 57 lb/yr for HNR facilities with HRSGs and 152 lb/yr for HNR facilities without HRSGs, while mercury reduction under Approach 2 is 54 lb/yr for HNR facilities with HRSGs and 144 lb/yr for HNR facilities without HRSGs. Nonmercury metal reduction under Approach 1 is 1.4 tpy for HNR facilities with HRSGs and 3.8 tpy for HNR facilities without HRSGs, while nonmercury metal reduction under Approach 2 is 1.5 tpy for HNR facilities with HRSGs and 4.0 tpy for HNR facilities without HRSGs.

The BTF Approach 2 achieves similar (although slightly lower) reductions of mercury compared to Approach 1 at similar cost effectiveness (slightly higher $/lb for HNR with HRSG but same $/lb value for HNR without HRSGs). However, Approach 2 includes much more cost-effective controls for nonmercury HAP (COE) metals and slightly more reductions.

We conclude that both approaches are cost-effective for mercury. Regarding nonmercury metals, the BTF Approach 2 is clearly cost-effective based on historical decisions regarding nonmercury HAP metals (for example, the EPA accepted cost effectiveness of $1.3 million per ton HAP metals in the 2012 Secondary Lead Smelters RTR final rule based on 2009 dollars). BTF Approach 1 also could potentially be considered cost-effective for nonmercury metals. However, we conclude it is appropriate to propose the more cost-effective approach because it achieves similar reductions of the COE HAP metals at lower cost. With regard to the other three COE HAP from HNR without a HRSG subcategory (acid gases, formaldehyde and PAHs), based on consideration of capital costs, annual costs and cost effectiveness, we are proposing MACT floor limits (not BTF limits).

For the nonrecovery facility without HRSGs subcategory, the potential BTF limits for COE HAP emitted as nonmercury HAP metals and mercury were calculated by assuming the addition of a baghouse (with estimated 99.9 percent reduction for metals) and ACI (with 90 percent reduction for mercury). We then compared the limits to the applicable 3xRDL value to ensure a measurable standard. For HAP metals, the 3xRDL value was greater than the BTF limit, and thus the proposed BTF standard was set at the 3xRDL value (a measurable value), which is 2 percent of the level of the MACT floor standard. For mercury, the 3xRDL value was less than the BTF UPL limit, and thus the proposed BTF standard was set at the BTF UPL limit. The results and proposed decisions based on the analyses performed pursuant to CAA sections 112(d)(2) and (3) for HNR bypass/waste heats stacks are presented in Table 7.

Table 7—MACT Floor and BTF Standards Developed for Emissions From Coke Ovens HNR HRSG Bypass/Waste Heat Stacks Sources

Source or process

Pollutant

Type of MACT standard

Existing

New

HNR bypass/waste heat stack for 2 subcategories (for all 5 HNR facilities)

acid gases

Formaldehyde

PAH

0.13 gr/dscf [UPL]

0.0011 gr/dscf

2.4E-06 gr/dscf [UPL]

0.070 gr/dscf [UPL].

1.9E-05 gr/dscf.

2.4E-06 gr/dscf [UPL].

Heat recovery facilities (only) bypass/waste heat stack (with HRSGs) subcategory

Mercury

1.7E-05 gr/dscf [UPL]

0.034 gr/dscf [UPL]

7.8E-06 gr/dscf [UPL].

0.025 gr/dscf [UPL].

Nonrecovery facilities (only) waste heat stack (without HRSGs) (BTF) subcategory

Mercury

BTF 1.7E-06 gr/dscf

BTF 6.6E-04 gr/dscf

BTF 7.8E-07 gr/dscf.

BTF 6.6E-04 gr/dscf.

gr/dscf = grains per dry standard cubic feet. RDL = representative detection level. UPL is the upper performance limit. PM is a surrogate for nonmercury metal HAP.

Once the bypass/waste heat stacks COE pass through control devices, the emissions are no longer considered COE.

We are proposing that testing for compliance with these proposed MACT and BTF limits be performed every 5 years. Annualized costs for testing, including recordkeeping and reporting, are estimated to be $3.2 million/year for the 11 operating facilities in the source category, or an average of $290,000 per year per facility.

We are soliciting comments regarding other potential approaches to establish emissions standards for the HRSG main stacks and bypass stacks, including: (1) whether the EPA should consider the emission points all together (

i.e.,

HRSG main stack plus HRSG bypass stack emissions) and establish standards based on the best five units or best five facilities including emissions from the HRSGs and their control devices, and emissions from the bypass over a period of time (

e.g.,

per year or per month); or (2) a standard that is based in part on limiting the number of hours per year or per month that bypass stacks can be used.

We are also soliciting comments regarding the use of bypass stacks. For the Coke Ovens: Pushing, Quenching, Battery Stacks source category, we understand that bypass of HRSGs is needed for maintenance and repair of HRSGs or their control devices. Furthermore, the facilities recover heat from coke oven exhaust and sell or produce power for sale, so they lose revenue when bypass is used; therefore, it is in the facilities' interest to not bypass HRSGs. For this source category's HNR subcategory, we have emissions tests data and, therefore, are able to propose numeric emissions limits for these emissions sources. We solicit comments regarding whether the EPA should consider other approaches to regulate bypass stacks.

For details of how these MACT and BTF standards were developed and other BTF options that were considered see the MACT/BTF memorandum,

located in the docket for the proposed rule (EPA-HQ-OAR-2002-0085).

B. What are the results of the risk assessment and analyses for the coke ovens: pushing, quenching, and battery stacks source category?

1. Chronic Inhalation Risk Assessment Results

The results of the chronic baseline inhalation cancer risk assessment indicate that, based on estimates of current actual emissions, the MIR posed by the Coke Ovens: Pushing, Quenching, and Battery Stacks source category is 9-in-1 million driven by arsenic emissions primarily from bypass/waste heat stacks. The total estimated cancer incidence based on actual emission levels is 0.02 excess cancer cases per year, or 1 case every 50 years. No people are estimated to have inhalation cancer risks above 100-in-1 million due to actual emissions, and the population exposed to cancer risks greater than or equal to 1-in-1 million is approximately 2,900 (see Table 8 of this preamble). In addition, the maximum modeled chronic noncancer TOSHI for the source category based on actual emissions is estimated to be 0.1 (for developmental effects from arsenic emissions).

Table 8—Coke Oven Pushing, Quenching, and Battery Stacks Source Category Inhalation Risk Assessment Results

Risk assessment

Number of

facilities

Maximum

individual

cancer risk

(in 1 million)

Estimated

population at

increased risk

of cancer

≥1-in-1 million

Estimated

annual

cancer

incidence

(cases per year)

Maximum

chronic

noncancer TOSHI

Maximum screening acute noncancer HQ

Based on Actual Emissions Level

Source Category Emissions

2,900

0.02

0.1 (arsenic)

REL

= 0.6 (arsenic).

Facility-Wide

2.7 million

0.2

2 (hydrogen cyanide)

REL

= 0.6 (arsenic).

Based on Allowable Emissions Level

Source Category Emissions

440,000

0.05

0.2 (arsenic)

Maximum individual excess lifetime cancer risk due to HAP emission.

See “Facility-Wide Risk Results” in section III.C.6. of this preamble for more detail on this risk assessment.

Considering MACT-allowable emissions, results of the inhalation risk assessment indicate that the cancer MIR is 10-in-1 million, driven by arsenic emissions primarily from HNR pushing and bypass/waste heat stacks. The total estimated cancer incidence from this source category based on allowable emissions is 0.05 excess cancer cases per year, or one excess case every 20 years. No people are estimated to have inhalation cancer risks above 100-in-1 million due to allowable emissions, and the population exposed to cancer risks greater than or equal to 1-in-1 million is approximately 440,000. In addition, the maximum modeled chronic noncancer TOSHI for the source category based on allowable emissions is estimated to be 0.2 (for developmental effects from arsenic emissions).

2. Screening Level Acute Risk Assessment Results

As presented in Table 8 of this preamble, the estimated worst-case off-site acute exposures to emissions from the Coke Ovens: Pushing, Quenching, and Battery Stacks source category result in a maximum modeled acute HQ of 0.6 based on the REL for arsenic. Detailed information about the assessment is provided in

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.

3. Multipathway Risk Screening Results

Of the 14 facilities in the source category, all 14 emit PB-HAP, including arsenic, cadmium, dioxins, mercury, and POMs. Emissions of these PB-HAP from each facility were compared to the respective pollutant-specific Tier 1 screening emission thresholds. The Tier 1 screening analysis indicated 14 facilities exceeded the Tier 1 emission threshold for arsenic, dioxins, mercury, and POM; and two facilities exceeded for cadmium.

For facilities that exceeded the Tier 1 multipathway screening threshold emission rate for one or more PB-HAP, we used additional facility site-specific information to perform a Tier 2 multipathway risk screening assessment. The multipathway risk screening assessment based on the Tier 2 gardener scenario resulted in a maximum cancer Tier 2 cancer screening value (SV) equal to 400 driven by arsenic emissions. Individual Tier 2 cancer screening values for dioxin and POM emissions were less than 1 for the gardener scenario. The maximum Tier 2 cancer SV, based on the fisher scenario, is equal to 10, with arsenic and dioxin emissions contributing to the SV, with a maximum individual Tier 2 SV of 10 for arsenic and a maximum Tier 2 SV of 5 for dioxin emissions. The maximum POM SV was less than 1. The multipathway risk screening assessment based on the Tier 2 fisher scenario resulted in a maximum noncancer Tier 2 SV equal to 6 for methyl mercury and less than 1 for cadmium emissions.

A Tier 3 cancer screening assessment was performed for arsenic based on the gardener scenario as well as a Tier 3 noncancer screening assessment for methyl mercury based on the fisher scenario. The Tier 3 gardener scenario was refined by identifying the location of the residence most impacted by arsenic emissions from the facility as opposed to the worst-case near-field location used in the Tier 2 assessment. Based on these Tier 3 refinements to the gardener scenario, the maximum Tier 3 cancer screening value for arsenic was adjusted from 400 to 300. For the fisher scenario, we evaluated the Tier 2 noncancer SV for methyl mercury, to determine whether the results would change based on a review of the lakes, to determine if they were fishable. This review resulted in no change to the Tier 2 noncancer SV of 6 for methyl mercury.

An exceedance of a screening threshold emission rate or SV in any of the tiers cannot be equated with a risk value or an HQ (or HI). Rather, it represents a high-end estimate of what the risk or hazard may be. For example, an SV of 6 for a noncarcinogen can be interpreted to mean that the Agency is confident that the HQ would be lower than 6. Similarly, a Tier 2 cancer SV of 300 means that we are confident that the cancer risk is lower than 300-in-1 million. Our confidence comes from the conservative, or health-protective, assumptions encompassed in the screening tiers. The Agency chooses inputs from the upper end of the range of possible values for the influential parameters used in the screening tiers, and the Agency assumes that the exposed individual exhibits ingestion behavior that would lead to a high total exposure.

The EPA determined that it is not necessary to go beyond the Tier 3 gardener or Tier 2 fisher scenario and conduct a site-specific assessment for arsenic and mercury. The EPA compared the Tier 2 and 3 screening results to site-specific risk estimates for five previously assessed source categories. These are the five source categories, assessed over the past 4 years, which had characteristics that make them most useful for interpreting the Coke Ovens: Pushing, Quenching, and Battery Stacks screening results. For these source categories, the EPA assessed fisher and/or gardener risks for arsenic, cadmium, and/or mercury by conducting site-specific assessments. The EPA used AERMOD for air dispersion and Tier 2 screens that used multi-facility aggregation of chemical loading to lakes where appropriate. These assessments indicated that cancer and noncancer site-specific risk values were at least 50 times lower than the

respective Tier 2 screening values for the assessed facilities, with the exception of noncancer risks for cadmium for the gardener scenario, where the reduction was at least 10 times (refer to EPA Docket ID: EPA-HQ-OAR-2017-0015 and EPA-HQ-OAR-2019-0373 for a copy of these reports).

EPA Docket records (EPA-HQ-OAR-2017-0015):

Appendix 11 of the Residual Risk Assessment for the Taconite Manufacturing Source Category in Support of the Risk and Technology Review 2019 Proposed Rule; Appendix 11 of the Residual Risk Assessment for the Integrated Iron and Steel Source Category in Support of the Risk and Technology Review 2019 Proposed Rule; Appendix 11 of the Residual Risk Assessment for the Portland Cement Manufacturing Source Category in Support of the 2018 Risk and Technology Review Final Rule; Appendix 11 of the Residual Risk Assessment for the Coal and Oil-Fired EGU Source Category in Support of the 2018 Risk and Technology Review Proposed Rule;

and EPA Docket: (EPA-HQ-OAR-2019-0373):

Appendix 11

of the

Residual

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