27002 Federal Register / Vol. 87, No. 88 / Friday, May 6, 2022 / Rules and Regulations 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 63 

[EPA–HQ–OAR–2020–0560; FRL–7546–02– 

OAR] 

RIN 2060–AU59 

National Emission Standards for 

Hazardous Air Pollutants: Mercury Cell 

Chlor-Alkali Plants Residual Risk and 

Technology Review 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: This action finalizes the 

residual risk and technology review 

(RTR) conducted for the Mercury Cell 

Chlor-Alkali Plants source category 

regulated under national emission 

standards for hazardous air pollutants 

(NESHAP). In addition, this action 

finalizes the beyond-the-floor 

determination that EPA performed in 

response to a petition for 

reconsideration of the 2003 NESHAP. 

These final amendments prohibit 

mercury emissions from existing 

mercury cell chlor-alkali plants based 

on the results of our technology review 

and our beyond-the-floor maximum 

achievable control technology (MACT) 

determination. The compliance date for 

this requirement is three years. Since 

mercury emissions will be eliminated as 

a result of the final rule standards, any 

adverse health or environmental effects 

from mercury emissions from the source 

category will also be eliminated in that 

three-year time frame. Furthermore, the 

EPA is finalizing work practice 

standards and instrumental monitoring 

of mercury to minimize fugitive 

mercury emissions from the cell rooms 

during the period of time before 

emissions are eventually eliminated. In 

addition, the EPA is finalizing work 

practice standards to minimize fugitive 

chlorine emissions from mercury cell 

chlor-alkali plants, which were not 

previously regulated under the 

NESHAP. The EPA is also finalizing 

revisions related to emissions during 

periods of startup, shutdown, and 

malfunction (SSM) and amendments to 

correct a few minor errors in 

compliance provisions in the 2003 rule. 

DATES: This final rule is effective on 

May 6, 2022. 

ADDRESSES: The U.S. Environmental 

Protection Agency (EPA) has established 

a docket for this action under Docket ID 

No. EPA–HQ–OAR–2020–0560. All 

documents in the docket are listed on 

the https://www.regulations.gov/ 

website. Although listed, some 

information is not publicly available, 

e.g., Confidential Business Information

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

form. Publicly available docket

materials are available electronically

through https://www.regulations.gov/,

or in hard copy at the EPA Docket

Center, WJC West Building, Room

Number 3334, 1301 Constitution Ave.

NW, Washington, DC. The Public

Reading Room hours of operation are

8:30 a.m. to 4:30 p.m. Eastern Standard

Time (EST), Monday through Friday.

The telephone number for the Public

Reading Room is (202) 566–1744, and

the telephone number for the EPA

Docket Center is (202) 566–1742. Hand

Deliveries and couriers may be received

by scheduled appointment only. For

further information and updates on EPA

Docket Center services and the current

status, please visit us online at https://

www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: For

questions about this final action, contact

Phil Mulrine, Sector Policies and

Programs Division (D243–02), Office of

Air Quality Planning and Standards,

U.S. Environmental Protection Agency,

Research Triangle Park, North Carolina

27711; telephone number: (919) 541–

5289; fax number: (919) 541–4991; and

email address: mulrine.phil@epa.gov.

For specific information regarding the

risk modeling methodology, contact

James Hirtz, Health and Environmental

Impacts Division, Office of Air Quality

Planning and Standards, U.S.

Environmental Protection Agency,

Research Triangle Park, North Carolina

27711; telephone number: (919) 541–

0881; fax number: (919) 541–0840; and

email address: hirtz.james@epa.gov.

SUPPLEMENTARY INFORMATION:

Preamble acronyms and 

abbreviations. We use multiple 

acronyms and terms in this preamble. 

Throughout this document wherever 

‘‘we,’’ ‘‘us,’’ or ‘‘our’’ is used, it is 

intended to refer to the EPA. 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: 

AEGL acute exposure guideline level two 

CAA Clean Air Act 

CFR Code of Federal Regulations 

Cl2 Chlorine 

CRA Congressional Review Act 

EPA Environmental Protection Agency 

ERT Electronic Reporting Tool 

HAP hazardous air pollutants(s) 

HCl hydrochloric acid 

Hg mercury 

HI hazard index 

HQ hazard quotient 

MACT maximum achievable control 

technology 

MATS Mercury and Air Toxics Standards 

NAIC North American Industry 

Classification System 

NESHAP national emission standards for 

hazardous air pollutants 

NTTAA National Technology Transfer and 

Advancement Act 

NOCS Notification of Compliance Status 

report 

NRDC Natural Resources Defense Council 

OMB Office of Management and Budget 

PB–HAP HAPs known to be persistent and 

bioaccumulative in the environment 

PDF portable document format 

PM particulate matter 

ppm parts per million 

ppmv parts per million by volume 

PRA Paperwork Reduction Act 

REL reference exposure limit 

RTR risk and technology review 

SSM startup, shutdown, and malfunction 

SV screening value 

TOSHI target organ-specific hazard index 

tpy tons per year 

UMRA Unfunded Mandates Reform Act 

Background information. On January 

8, 2021, the EPA proposed revisions to 

the 2003 Mercury Cell Chlor-Alkali 

Plants NESHAP, 40 CFR part 63, subpart 

IIIII, based on our RTR and MACT 

beyond-the-floor analyses (86 FR 1362, 

January 8, 2021). In this action, we are 

finalizing decisions and revisions for 

the rule. We summarize the comments 

we timely received regarding the 

proposed rule and provide our 

responses in this preamble. A ‘‘track 

changes’’ version of the regulatory 

language that incorporates the changes 

in this action is available in the docket. 

Organization of this document. The 

information in this preamble is 

organized as follows: 

I. General Information

A. Does this action apply to me?

B. Where can I get a copy of this document

and other related information?

C. Judicial Review and Administrative

Reconsideration

II. Background

A. What is the statutory authority for this

action?

B. What is the Mercury Cell Chlor-Alkali

Plants source category and how does the

NESHAP regulate HAP emissions from

the source category?

C. What changes did we propose for the

Mercury Cell Chlor-Alkali Plants source

category in our January 8, 2021 proposal?

III. What is included in this final rule?

A. What are the final rule amendments

based on the risk review for the Mercury

Cell Chlor-Alkali Plants source category?

B. What are the final rule amendments

related to a non-mercury option for the

Mercury Cell Chlor-Alkali Plants Source

Category pursuant to CAA sections

112(d)(2), (3), and (6)?

C. What are the final rule amendments

based on the technology review for the


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Mercury Cell Chlor-Alkali Plants source 

category? 

D. What are the final rule amendments 

pursuant to sections 112(d)(2) and (3) 

and (h) for the Mercury Cell Chlor-Alkali 

Plants source category? 

E. What are the final rule amendments 

addressing emissions during periods of 

startup, shutdown, and malfunction? 

F. What are the effective and compliance 

dates of the standards? 

IV. What is the rationale for our final 

decisions and amendments for the 

Mercury Cell Chlor-Alkali Plants source 

category? 

A. Residual Risk Review for the Mercury 

Cell Chlor-Alkali Plants Source Category 

B. Non-Mercury Option for the Mercury 

Cell Chlor-Alkali Plants Source Category 

C. Technology Review for the Mercury Cell 

Chlor-Alkali Plants Source Category 

D. Amendments Pursuant to Sections 

112(d)(2) and (3) and (h) for the Mercury 

Cell Chlor-Alkali Plants Source Category 

E. Amendments Addressing Emissions 

During Periods of Startup, Shutdown, 

and Malfunction and Other Topics 

F. Public Notice and Comments 

V. Summary of Cost, Environmental, and 

Economic Impacts and Additional 

Analyses Conducted 

A. What are the affected facilities? 

B. What are the air quality and other 

environmental impacts? 

C. What are the cost impacts? 

D. What are the economic impacts? 

E. What are the benefits? 

F. What analysis of environmental justice 

did we conduct? 

G. What analysis of children’s 

environmental health did we conduct? 

VI. Statutory and Executive Order Reviews 

A. Executive Orders 12866: Regulatory 

Planning and Review and Executive 

Order 13563: Improving Regulation and 

Regulatory Review 

B. Paperwork Reduction Act (PRA) 

C. Regulatory Flexibility Act (RFA) 

D. Unfunded Mandates Reform Act 

(UMRA) 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

H. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer and 

Advancement Act (NTTAA) 

J. Executive Order 12898: Federal Actions 

To Address Environmental Justice in 

Minority Populations and Low-Income 

Populations 

K. Congressional Review Act (CRA) 

I. General Information 

A. Does this action apply to me? 

Regulated entities. Categories and 

entities potentially regulated by this 

action are shown in Table 1 of this 

preamble. 

TABLE 1—NESHAP AND INDUSTRIAL

SOURCE CATEGORIES AFFECTED BY

THIS FINAL ACTION

NESHAP and source category NAICS1

code 

Mercury Cell Chlor-Alkali Plants 325180 

1 North America Industry Classification 

System. 

Table 1 of this preamble is not 

intended to be exhaustive, but rather to 

provide a guide for readers regarding 

entities likely to be affected by the final 

action for the source category listed. To 

determine whether your facility is 

affected, you should examine the 

applicability criteria in the appropriate 

NESHAP. If you have any questions 

regarding the applicability of any aspect 

of this NESHAP, please contact the 

appropriate person listed in the 

preceding FOR FURTHER INFORMATION

CONTACT section of this preamble. 

B. Where can I get a copy of this 

document and other related 

information? 

In addition to being available in the 

docket, an electronic copy of this final 

action will also be available on the 

internet. Following signature by the 

EPA Administrator, the EPA will post a 

copy of this final action at: https://

www.epa.gov/stationary-sources-airpollution/mercury-cell-chloralkaliplants-national-emissions-standards. 

Following publication in the Federal 

Register, the EPA will post the Federal 

Register version and key technical 

documents at this same website. 

Additional information is available on 

the RTR website at https://

www.epa.gov/stationary-sources-airpollution/risk-and-technology-reviewnational-emissions-standardshazardous. This information includes 

an overview of the RTR program and 

links to project websites for the RTR 

source categories. 

C. Judicial Review and Administrative 

Reconsideration 

Under Clean Air Act (CAA) section 

307(b)(1), judicial review of this final 

action is available only by filing a 

petition for review in the United States 

Court of Appeals for the District of 

Columbia Circuit (the Court) by July 5, 

2022. Under CAA section 307(b)(2), the 

requirements established by this final 

rule may not be challenged separately in 

any civil or criminal proceedings 

brought by the EPA to enforce the 

requirements. 

Section 307(d)(7)(B) of the CAA 

further provides that only an objection 

to a rule or procedure which was raised 

with reasonable specificity during the 

period for public comment (including 

any public hearing) may be raised 

during judicial review. This section also 

provides a mechanism for the EPA to 

reconsider the rule if the person raising 

an objection can demonstrate to the 

Administrator that it was impracticable 

to raise such objection within the period 

for public comment or if the grounds for 

such objection arose after the period for 

public comment (but within the time 

specified for judicial review) and if such 

objection is of central relevance to the 

outcome of the rule. Any person seeking 

to make such a demonstration should 

submit a Petition for Reconsideration to 

the Office of the Administrator, U.S. 

EPA, Room 3000, WJC South Building, 

1200 Pennsylvania Ave. NW, 

Washington, DC 20460, with a copy to 

both the person(s) listed in the 

preceding FOR FURTHER INFORMATION

CONTACT section, and the Associate 

General Counsel for the Air and 

Radiation Law Office, Office of General 

Counsel (Mail Code 2344A), U.S. EPA, 

1200 Pennsylvania Ave. NW, 

Washington, DC 20460. 

II. Background 

A. What is the statutory authority for 

this action? 

Section 112 of the CAA establishes a 

two-stage regulatory process to address 

emissions of hazardous air pollutants 

(HAP) from stationary sources. In the 

first stage, we must identify categories 

of sources emitting one or more of the 

HAP listed in CAA section 112(b) and 

then promulgate technology-based 

NESHAP for those sources. ‘‘Major 

sources’’ are those that emit, or have the 

potential to emit, any single HAP at a 

rate of 10 tons per year (tpy) or more, 

or 25 tpy or more of any combination of 

HAP. For major sources, these standards 

are commonly referred to as MACT 

standards and must reflect the 

maximum degree of emission reductions 

of HAP achievable (after considering 

cost, energy requirements, and non-air 

quality health and environmental 

impacts). In developing MACT 

standards, CAA section 112(d)(2) directs 

the EPA to consider the application of 

measures, processes, methods, systems, 

or techniques, including, but not limited 

to, those that reduce the volume of or 

eliminate HAP emissions through 

process changes, substitution of 

materials, or other modifications; 

enclose systems or processes to 

eliminate emissions; collect, capture, or 

treat HAP when released from a process, 

stack, storage, or fugitive emissions 

point; are design, equipment, work 


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1The Court has affirmed this approach of 

implementing CAA section 112(f)(2)(A): NRDC, 529 

F.3d at 1083 (‘‘If EPA determines that the existing 

technology-based standards provide an ′ample 

margin of safety,’ then the Agency is free to readopt 

those standards during the residual risk 

rulemaking.’’). 

practice, or operational standards; or 

any combination of the above. 

For these MACT standards, the statute 

specifies certain minimum stringency 

requirements, which are referred to as 

MACT floor requirements, and which 

may not be based on cost 

considerations. See CAA section 

112(d)(3). For new sources, the MACT 

floor cannot be less stringent than the 

emission control achieved in practice by 

the best-controlled similar source. The 

MACT standards for existing sources 

can be less stringent than floors for new 

sources, but they cannot be less 

stringent than the average emission 

limitation achieved by the bestperforming 12 percent of existing 

sources in the category or subcategory 

(or the best-performing five sources for 

categories or subcategories with fewer 

than 30 sources). In developing MACT 

standards, we must also consider 

control options that are more stringent 

than the floor under CAA section 

112(d)(2). We may establish standards 

more stringent than the floor, based on 

the consideration of the cost of 

achieving the emissions reductions, any 

non-air quality health and 

environmental impacts, and energy 

requirements. 

In the second stage of the regulatory 

process, the CAA requires the EPA to 

undertake two different analyses, which 

we refer to as the technology review and 

the residual risk review. Under the 

technology review, we must review the 

technology-based standards and revise 

them ‘‘as necessary (taking into account 

developments in practices, processes, 

and control technologies)’’ no less 

frequently than every 8 years, pursuant 

to CAA section 112(d)(6). In conducting 

this review, the EPA is not required to 

recalculate the MACT floors that were 

established in earlier rulemakings. 

Natural Resources Defense Council v. 

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

2008) (NRDC). Association of Battery 

Recyclers, Inc. v. EPA, 716 F.3d 667 

(D.C. Cir. 2013). The EPA may consider 

cost in deciding whether to revise the 

standards pursuant to CAA section 

112(d)(6). The EPA is required to 

address regulatory gaps, such as missing 

standards for listed air toxics known to 

be emitted from the source category, and 

any new MACT standards must be 

established under CAA sections 

112(d)(2) and (3), or, in specific 

circumstances, CAA sections 112(d)(4) 

or (h). Louisiana Environmental Action 

Network v. EPA, 955 F.3d 1088 (D.C. 

Cir. 2020) (LEAN). Under the residual 

risk review, we must evaluate the risk 

to public health remaining after 

application of the technology-based 

standards and revise the standards, if 

necessary, to provide an ample margin 

of safety to protect public health or to 

prevent, taking into consideration costs, 

energy, safety, and other relevant 

factors, an adverse environmental effect. 

The residual risk review is required 

within 8 years after promulgation of the 

technology-based standards, pursuant to 

CAA section 112(f). In conducting the 

residual risk review, if the EPA 

determines that the current standards 

provide an ample margin of safety to 

protect public health, it is not necessary 

to revise the MACT standards pursuant 

to CAA section 112(f).1 For more 

information on the statutory authority 

for this rule, see https://

www.federalregister.gov/documents/ 

2021/01/08/2021-00174/nationalemission-standards-for-hazardous-airpollutants-mercury-cell-chlor-alkaliplants-residual. 

B. What is the Mercury Cell Chlor-Alkali 

Plants source category and how does the 

NESHAP regulate HAP emissions from 

the source category? 

The EPA promulgated the Mercury 

Cell Chlor-Alkali Plants NESHAP on 

December 19, 2003 (68 FR 70904). The 

standards are codified at 40 CFR part 63, 

subpart IIIII. The mercury cell chloralkali industry consists of facilities that 

use mercury cells to manufacture 

product chlorine, product caustic, and 

by-product hydrogen via an electrolytic 

process. The source category covered by 

these MACT standards currently 

includes one operating facility, 

Westlake located in West Virginia. 

Subpart IIIII covers both major and 

area sources. The single remaining 

operational mercury cell-chlor-alkali 

plant in the category is located at a 

major source site. In addition to subpart 

IIII, processes at this major source site 

are subject to subparts ZZZZ 

(Reciprocating Internal Combustion 

Engine NESHAP) and DDDDD 

(Industrial/Commercial/Institutional 

Boilers and Process Heaters). The 

mercury cell chlor-alkali NESHAP 

includes standards for mercury 

emissions from two types of affected 

sources at plant sites where chlorine 

and caustic are produced in mercury 

cells: Mercury cell chlor-alkali 

production facility affected sources and 

mercury recovery facility affected 

sources. The 2003 rule prohibited 

mercury emissions from new and 

reconstructed mercury cell chlor-alkali 

production affected sources. 40 CFR 

63.8190(a)(1). For existing mercury cell 

chlor-alkali production affected sources, 

the 2003 standards included emission 

limitations for mercury emissions from 

process vents (including emissions from 

end-box ventilation systems and 

hydrogen systems) and work practices 

for fugitive mercury emissions from the 

cell room. 40 CFR 63.8190(a)(2), 

63.8192(a) through (f). 

For new, reconstructed, and existing 

mercury recovery facilities, the 2003 

NESHAP included emission limitations 

for mercury emissions from oven type 

thermal recovery unit vents and nonoven type thermal recovery unit vents. 

40 CFR 63.8190(a)(3). Note that the 

single remaining operational facility 

does not operate a mercury recovery 

facility, so there are no operating 

mercury recovery facilities subject to 

subpart IIIII. 

The 2003 rule did not promulgate 

standards for chlorine (Cl2) or 

hydrochloric acid (HCl), citing the 

authority of section 112(d)(4) of the 

CAA (68 FR 70906). In its 2003 action 

(68 FR 70904), the EPA promulgated the 

initial Mercury Cell Chlor-Alkali Plants 

NESHAP pursuant to CAA section 

112(d)(2) and (3) and added the source 

category to the EPA’s Source Category 

List under CAA sections 112(c)(1), as 

well as under (c)(3), (c)(6) and (k)(3)(B), 

in each case because of the mercury 

emissions. 

Following promulgation of the 2003 

Mercury Cell Chlor-Alkali Plants 

NESHAP, the EPA received a petition to 

reconsider several aspects of the rule 

from the Natural Resources Defense 

Council (NRDC). NRDC also filed a 

petition for judicial review of the rule in 

the U.S. Court of Appeals for the District 

of Columbia Circuit. In a letter dated 

April 8, 2004, the EPA granted NRDC’s 

petition for reconsideration and on July 

20, 2004, the court placed the petition 

for judicial review in abeyance pending 

the EPA’s action on reconsideration. 

The EPA issued proposed revisions to 

the 2003 rule on June 11, 2008 (73 FR 

33258) and on March 14, 2011 (76 FR 

13852), to respond to the 

reconsideration petition. This final 

action completes EPA’s rulemaking 

following those two proposals and the 

third action proposed on January 8, 

2021 (86 FR 1362), and completes the 

EPA’s action in response to the 2004 

petition for reconsideration of the 2003 

rule. 


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C. What changes did we propose for the 

Mercury Cell Chlor-Alkali Plants source 

category in our January 8, 2021, 

proposal? 

On January 8, 2021, the EPA 

published a proposed rule in the 

Federal Register for the Mercury Cell 

Chlor-Alkali Plants NESHAP, 40 CFR 

part 63, subpart IIIII, that took into 

consideration the RTR analyses and the 

MACT beyond-the-floor analysis. In the 

proposed rule, we proposed: (1) The 

determination that risks due to 

emissions of HAP are acceptable from 

the Mercury Cell Chlor-Alkali Plants 

source category and that the 2003 

NESHAP provides an ample margin of 

safety to protect public health; (2) to 

amend the requirements for cell room 

fugitive mercury emissions to require 

work practice standards for the cell 

rooms plus instrumental monitoring of 

cell room fugitive mercury emissions 

under the technology review; (3) work 

practice standards for fugitive chlorine 

emissions from mercury cell chlor-alkali 

plants, which were not previously 

regulated under the NESHAP; (4) 

revisions related to emissions during 

periods of startup, shutdown and 

malfunction (SSM), which had also 

been addressed in the 2011 proposed 

rule; (5) provisions for electronic 

submission of performance test results, 

compliance reports, and Notification of 

Compliance Status (NOCS) reports; and 

(6) amendments to correct minor errors 

and improve the compliance provisions 

of the rule, which had also been 

addressed in the 2008 and 2011 

proposals. 

With regard to our technology review 

and an overdue beyond-the-floor 

determination, as explained in the 

January 2021 document (86 FR 1362, 

January 8, 2021), we evaluated two 

options: (1) Improved cell room mercury 

monitoring and work practices to 

minimize emissions; and (2) the 

elimination of Hg emissions by 

requiring the conversion to a non-Hg 

technology. 

Based on this evaluation, we 

proposed option 1, as mentioned above, 

however we also described option 2 

(mercury elimination) in detail in the 

January 2021 notice and solicited 

comments. Specifically, we explained 

that based on consideration of the 

updated costs and cost effectiveness and 

uncertainties, and given the passage of 

time, and the fact that the costeffectiveness data and analysis done in 

2011 were based on two facilities that 

are no longer operating, we questioned 

at that time whether those 2011 analyses 

would still be transferable to the one 

remaining operating facility. 

Consequently, we did not propose to 

require the elimination of mercury in 

the January 2021 document. However, 

we solicited comments, data, and other 

information regarding this proposed 

decision, including data and 

information regarding the capital and 

annual costs, cost effectiveness, non-air 

impacts, and other relevant information 

that would be relevant for the remaining 

facility regarding whether the NESHAP 

should include a zero-mercury standard 

as a beyond-the-floor MACT standard. 

We also stated that we intend to 

consider any such submitted data and 

information, in addition to the data and 

information contained in the records for 

the 2008 and 2011 proposals and in the 

2021 proposal, in reaching final 

conclusions regarding a zero-mercury 

standard (see 86 FR 1362, January 8, 

2021). 

III. What is included in this final rule? 

This action finalizes the EPA’s 

determinations pursuant to the RTR and 

MACT provisions of CAA section 112 

for the Mercury Cell Chlor-Alkali Plants 

source category and amends the 

Mercury Cell Chlor-Alkali Plants 

NESHAP based on those 

determinations. 

A. What are the final rule amendments 

based on the risk review for the Mercury 

Cell Chlor-Alkali Plants source 

category? 

No changes to the Mercury Cell ChlorAlkali Plants NESHAP are being 

promulgated to meet the requirements 

of CAA section 112(f). Under this 

action, for purposes of section 112(f), we 

are finalizing the risk assessments and 

our determination that the risks from 

the Mercury Cell Chlor-Alkali Plants 

source category are acceptable, the 2003 

standards provide an ample margin of 

safety to protect public health, and more 

stringent standards are not necessary to 

prevent an adverse environmental 

effect. 

B. What are the final rule amendments 

related to a non-mercury option for the 

Mercury Cell Chlor-Alkali Plants Source 

Category pursuant to sections 112(d)(2), 

(3), and (6)? 

To satisfy the requirements of CAA 

sections 112(d)(2), (d)(3), and (6), 

including to respond to the petition for 

reconsideration of the 2003 rule by 

completing our MACT beyond-the-floor 

analysis, we are revising the MACT 

standards to prohibit mercury emissions 

from existing mercury cell chlor-alkali 

plants. Specifically, these amendments 

prohibit mercury emissions from 

existing mercury chlor-alkali production 

facility affected sources. This makes the 

mercury standard for existing sources 

the same as the standard for new and 

reconstructed sources that has been in 

the NESHAP since 2003. Since we 

conclude that it is improbable that a 

mercury cell chlor-alkali plant can be 

operated without mercury emissions, 

we expect this revision will effectively 

require the lone remaining mercury cell 

chlor-alkali plant in operation in the 

U.S. to cease production of chlorine 

with their single mercury cell 

production unit. We anticipate the 

facility will continue to produce 

chlorine through its other, highervolume non-mercury chlorine 

production units located at the Westlake 

facility and may convert the mercury 

cell unit to a membrane cell or other 

non-mercury chlorine production 

process. There are no mercury recovery 

facilities still in operation in the U.S. 

This final rule provides a three-year 

period to comply with the requirement 

to eliminate mercury emissions from the 

single remaining existing affected 

source. To demonstrate compliance, the 

owner or operator will need to submit 

a notification certifying that all mercury 

emissions have been eliminated 

permanently no later than 120 days after 

the compliance date. 

C. What are the final rule amendments 

based on the technology review for the 

Mercury Cell Chlor-Alkali Plants source 

category? 

We determined that there are 

developments in practices, processes, 

and control technologies that warrant 

revisions to the MACT standards for this 

source category. As noted above, we are 

revising the MACT standards to include 

a prohibition of mercury emissions, 

which is based on both a section 

112(d)(6) technology review and our 

beyond-the-floor review under section 

112(d)(2) and (3) in response to NRDC’s 

2004 petition for reconsideration. Also 

based on the section 112(d)(6) 

technology review and in response to 

NRDC’s 2004 petition, we are amending 

the requirements for cell room fugitive 

mercury emissions to require work 

practice standards for the cell rooms 

along with instrumental monitoring of 

cell room fugitive mercury emissions 

during the period of time before 

emissions are eventually eliminated. In 

addition, under the technology review, 

we identified a regulatory gap, and as 

discussed below, we are establishing 

new standards under CAA section 

112(h). 


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D. What are the final rule amendments 

pursuant to sections 112(d)(2) and (3) 

and (h) for the Mercury Cell ChlorAlkali Plants source category? 

In addition to the requirements for 

mercury described above, we are also 

finalizing amendments pursuant to 

section 112(h) for chlorine emissions, 

similar to the standards we proposed in 

January 2021 (86 FR 1362), that require 

implementation of work practices to 

minimize chlorine emissions from the 

mercury cell chlor-alkali processes. 

Further details regarding these work 

practice standards are described in 

section IV.D of this document. 

E. What are the final rule amendments 

addressing emissions during periods of 

startup, shutdown, and malfunction? 

We are finalizing amendments related 

to provisions that apply during periods 

of SSM that the EPA proposed on 

January 8, 2021. Further details are 

provided in section IV.E of this 

document. 

F. What are the effective and 

compliance dates of the standards? 

The revisions to the MACT standards 

being promulgated in this action are 

effective on May 6, 2022. The 

compliance date for existing mercury 

cell chlor-alkali plants to eliminate 

mercury emissions is May 6, 2025. 

These final amendments will 

essentially require that the single 

remaining operating mercury cell chloralkali facility either convert its one 

mercury cell unit to a non-mercury 

technology (its other units are already 

using non-mercury technology) or close 

that mercury cell unit and thereafter 

rely solely on its other non-mercury 

units for chlorine production. Either of 

these options will require significant 

time for the company to reach a 

decision and to develop and implement 

a plan of action. For example, it is 

expected that it could take between six 

months and one year to develop an 

engineering design and plan for 

conversion. The facility would then 

need to solicit bids for the conversion, 

which could take up to six months. 

Construction could then take up to two 

years. In addition, arrangements will 

need to be made to dismantle the 

mercury cell facility, to store the 

elemental mercury removed from the 

cells and to dispose of the mercurycontaminated wastes. The most recent 

conversion in the U.S. was the facility 

in Ashtabula, Ohio. This Ashtabula 

facility was, like the West Virginia, 

facility, one of the smaller capacity 

mercury cell units in the U.S. (less than 

75,000 tons of chlorine per year). It was 

also of similar age (Ashtabula 

constructed in 1963 and West Virginia 

in 1958) and was located in a 

neighboring state. The company 

announced the plans to convert their 

mercury cell process to membrane cells 

in 2014. They broke ground in 2017 and 

the conversion was complete in 2020. In 

conclusion, six years elapsed between 

the time the decision to convert was 

made and the conversion was 

completed, which included three full 

years for the dismantling/construction. 

Therefore, we conclude that the full 

three-year compliance period allowed 

by section 112(i)(3) of the CAA to meet 

new or revised emission standards is 

warranted. Moreover, as discussed 

further below, this period will provide 

ample time for the United States, via the 

elimination of mercury emissions from 

the plant, to meet its obligations to 

eliminate mercury emissions from this 

source category under the international 

treaty known as the Minamata 

Convention. 

For existing sources, in 2021, we 

proposed two changes to the work 

practice standards. One of these changes 

was the requirement to operate a cellroom mercury monitoring program in 

addition to mercury work practices. 

This change was proposed in both 2008 

and 2011. The second proposed change 

is a program to require work practices 

to reduce fugitive chlorine emissions. 

While these proposed work practice 

standards were based on the practices in 

place at the single facility in the source 

category, they will require some 

modifications to the procedures 

currently employed at the facility. 

Specifically, they will need to develop 

and implement a recordkeeping system 

to record and maintain the records 

required for the mercury cell and 

fugitive chlorine work practices and to 

incorporate the required material in the 

requisite reports. As proposed, we are 

providing 180 days for the facility to 

modify their current procedures. 

Therefore, the mercury and chlorine 

work practice standards being 

promulgated in this action require 

compliance on November 2, 2022. 

We also proposed in January 2021, a 

change to the SSM requirements to 

remove the exemption from the 

requirements to meet the standards 

during SSM periods and to remove the 

requirement to develop and implement 

an SSM plan. This change was also 

proposed in 2008 and 2011. Our 

experience with similar industries 

shows that this sort of regulated facility 

generally requires a time period of 6 

months to read and understand the 

amended rule requirements; to evaluate 

their operations to ensure that they can 

meet the standards during periods of 

startup and shutdown as defined in the 

rule and make any necessary 

adjustments; and to update their 

operation, maintenance, and monitoring 

plans to reflect the revised 

requirements. As proposed, we are 

providing 180 days for the facility to 

comply with the revised SSM 

requirements. As such, these revisions 

require compliance by November 2, 

2022. 

IV. What is the rationale for our final 

decisions and amendments for the 

Mercury Cell Chlor-Alkali Plants 

source category? 

For each issue, this section provides 

a description of what we addressed in 

the proposed rules for the source 

category and what we are finalizing for 

the issue, the EPA’s rationale for the 

final decisions and amendments, and 

the comments and responses. 

A. Residual Risk Review for the Mercury 

Cell Chlor-Alkali Plants Source Category 

1. What did we propose pursuant to 

CAA Section 112(f) for the Mercury Cell 

Chlor-Alkali Plants source category? 

We proposed that health risks due to 

emissions of HAP from the Mercury Cell 

Chlor-Alkali Plants source category are 

acceptable, that the 2003 NESHAP 

provides an ample margin of safety to 

protect public health, and that no 

additional standards are necessary to 

prevent an adverse environmental 

effect. 

A two-step evaluation approach was 

used, similar to the approach applied in 

the Benzene NESHAP, to determine 

whether or not risks are acceptable and 

to determine whether the 2003 

standards provide an ample margin of 

safety to protect public health or needed 

to be revised to meet this goal. We 

considered health risk and other health 

information; information and additional 

factors relating to the appropriate level 

of control were also considered—e.g., 

cost and economic impacts of controls, 

technological feasibility, uncertainties, 

and any other relevant factors. 

Table 2 below provides a summary of 

the results of the inhalation risk 

assessment for the source category 

conducted for the January 2021 

proposal. More detailed information on 

the risk assessment can be found in the 

National Emission Standards for 

Hazardous Air Pollutants: Mercury Cell 


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Chlor-Alkali Plants Residual Risk and 

Technology Review supporting 

document, available in the docket for 

this action (Docket No.: EPA–HQ–OAR– 

2020–0560–0014). 

TABLE 2—INHALATION RISK ASSESSMENT SUMMARY FOR THE MERCURY CELL CHLOR-ALKALI PLANTS 1

[Source category] 

Risk assessment Number of 

facilities 2

Maximum 

individual 

cancer risk 

(1-in-1million) 3

Estimated 

population at 

increased risk of 

cancer 

≥1-in-1 million 

Estimated 

annual cancer 

incidence 

(cases per year) 

Maximum chronic 

noncancer TOSHI 4

Maximum screening 

acute noncancer HQ 5

Baseline Actual Emissions 

Source Category ..... 2 0.004 0 0.0000003 0.05 (respiratory) .... 2 (REL) 7E–4 (AEGL2). 

Facility-Wide ............ 2 0.3 0 0.0001 0.05 (respiratory).

Baseline Allowable Emissions 

Source Category ..... 2 0.004 0 0.0000003 0.05 (respiratory).

1Based on actual and allowable emissions. 

2When the risk assessment was completed in mid-2020, there were 2 operating facilities in the mercury cell chlor-alkali source category and 

both were subject to 40 CFR part 63, subpart IIIII. However, in late 2020 one of those facilities converted to a non-mercury process. Therefore, 

currently only one operating facility remains in the source category. 3 Maximum individual excess lifetime cancer risk due to HAP emissions from the source category. 

4 Maximum TOSHI. The target organ with the highest TOSHI for the source category is the respiratory system. 

5The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of HQ values. The acute HQ shown was based upon the lowest acute 1-hour dose-response value, the REL for mercury (elemental). When an HQ exceeds 1, we also show the HQ using the next lowest available acute dose-response value. 

As shown in the table above, for the 

Mercury Cell Chlor-Alkali Plants source 

category, the maximum cancer risk to 

the individual most exposed is less than 

1-in-1 million based on actual emissions 

and allowable emissions. The estimated 

incidence of cancer due to inhalation 

exposures for the source category is 

0.0000003 excess cancer cases per year, 

or one excess case every 3 million years. 

No one is exposed to cancer risk greater 

than or equal to 1-in-1 million based 

upon actual and allowable emissions. 

We estimated that the maximum 

chronic noncancer TOSHI from 

inhalation exposure is less than 1 (0.05 

[respiratory]). For both actual and 

allowable emissions, respiratory risks 

were driven by chlorine emissions from 

the mercury cell building. 

Based on our refined screening 

analysis of reasonable worst-case acute 

exposure to actual emissions from the 

category, the facility exceeded an HQ of 

1 (the HQ was 2), when compared to the 

1-hour REL for mercury (elemental). As 

discussed in section III.C.3.c of the 2021 

proposal preamble, we used an acute 

hourly multiplier of 10 for all emission 

processes. For this HAP, there are no 

AEGL–1 or ERPG–1 values for 

comparison, but AEGL–2 or ERPG–2 

values are available. For elemental 

mercury, when the maximum off-site 

concentration is compared with the 

AEGL–2 and ERPG–2, the maximum 

acute noncancer HQ is well below 1 

(0.0007). With regard to multipathway 

exposures, HAP known to be persistent 

and bioaccumulative in the 

environment (PB–HAP) emissions 

(based on estimates of actual emissions) 

were reported from both facilities in the 

source category with both exceeding the 

Tier 1 non-cancer screening threshold 

emission rate for mercury. A Tier 2 

screening analysis was conducted, and 

the facility did not have a screening 

value (SV) greater than 1 for any 

scenario (the fisher and farmer had the 

highest SV at 0.4). There are no 

carcinogenic PB–HAP emitted from the 

source category, so there are no cancer 

SVs to report. 

Considering all the health risk 

information and factors noted, the 

proposed determination was that the 

risks are acceptable and that no 

additional standards are necessary to 

prevent an adverse environmental 

effect. Under the ample margin of safety 

analysis, we evaluated the cost and 

feasibility of available control 

technologies and other measures that 

could be applied to further reduce the 

risks (or potential risks) due to 

emissions of HAP from the source 

category. After careful consideration of 

these options, since the risks due to 

mercury emissions were already low, 

we did not propose any additional 

standards for mercury under CAA 

section 112(f). 

2. How did the risk review change for 

the Mercury Cell Chlor-Alkali Plants 

source category? 

We made no changes to either the risk 

assessments or our determinations 

regarding risk acceptability, ample 

margin of safety, or adverse 

environmental effects for the Mercury 

Cell Chlor-Alkali Plants source category 

since the proposal was published on 

January 8, 2021. We are finalizing the 

risk review as proposed (86 FR 1362, 

January 8, 2021). 

3. What key comments did we receive 

on the risk review, and what are our 

responses? 

The only comment received regarding 

the risk assessment was that one 

commenter agreed with our assessment 

that emissions were low and that risks 

were low and at acceptable levels. 

4. What is the rationale for our final 

approach and final decisions for the risk 

review? 

As noted above, in 2021, we proposed 

that the 2003 Mercury Cell Chlor-Alkali 

NESHAP provides an ample margin of 

safety to protect public health without 

any revisions. Other than a general 

agreement with the results, there were 

no specific comments submitted on the 

risk review approach, results, or 

decision. Therefore, we are finalizing 

the proposed determination that the 

risks are acceptable, that the 2003 rule 

provides an ample margin of safety to 

protect public health and that no 

additional standards are necessary to 

prevent an adverse environmental 

effect. 


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B. Non-Mercury Option for the Mercury 

Cell Chlor-Alkali Plants Source Category 

1. What did we propose related to the 

non-mercury option for the Mercury 

Cell Chlor-Alkali Plants source 

category? 

We addressed this issue in all three of 

our proposed rules issued following 

promulgation of the 2003 rule, in 

response to the 2004 petition for 

reconsideration of the 2003 rule’s 

consideration of section 112(d)(2) and 

(3) beyond-floor options and most 

recently as part of the technology review 

under section 112(d)(6). In the 2021 

proposal, we further considered our two 

prior proposals, but did not re-propose 

the option to require non-mercury 

production technology for existing 

sources, which has been the 

requirement for new and reconstructed 

mercury cell chlor-alkali production 

sources since the rule was originally 

promulgated in 2003. This option was 

considered both as part of the 

technology review under the authority 

of section 112(d)(6) and as a ‘‘beyondthe-floor’’ option under sections 

112(d)(2) and (3). As explained in the 

several proposed rules, selecting this 

option would eliminate all mercury 

emissions by forcing the remaining 

facility to either convert to a nonmercury technology or close its mercury 

cell chlor-alkali operations. While we 

did not in 2021, re-propose this option 

under either 112(d)(2) and (3) or (d)(6), 

we described this option in detail in the 

proposed rule’s Federal Register (FR) 

notice published on January 8, 2021 (86 

FR 1362), including the estimated 

capital costs, annualized costs and cost 

effectiveness if it were to be adopted, 

and we specifically solicited comments, 

data, and other information regarding 

this proposed decision. Furthermore, in 

the January 2021 FR document, we 

discussed and referred to the previous 

2011 proposed rule in which the EPA 

also analyzed expected capital costs, 

annualized costs and cost effectiveness 

of the then proposed non-mercury 

option but for which EPA had not taken 

final action at the time of the 2021 

proposal. 

2. What changed related to the nonmercury option for the Mercury Cell 

Chlor-Alkali Plants source category? 

After consideration of public 

comments received on the 2021 

proposed rule and further assessment of 

the expected costs, we have changed our 

2021 proposed decisions under sections 

112(d)(2) and (3) and (6) regarding the 

non-mercury option and the final rule 

includes an amendment that prohibits 

mercury emissions from existing 

mercury cell chlor-alkali plants as was 

proposed in 2011 under section 

112(d)(2) and (3). Existing mercury cell 

chlor-alkali plants will have three years 

to comply with this requirement. 

3. What key comments did we receive 

on the non-mercury option, and what 

are our responses? 

Comment: One commenter remarked 

that the EPA must revise MACT 

standards when it finds there have been 

developments in processes, products, or 

control technologies under CAA section 

112(d)(6) to reduce emissions to the 

maximum achievable degree. They 

further stated that it is achievable for 

facilities to switch to membrane cell 

technology, as demonstrated by the 

number of facilities that have already 

made this switch since adoption of the 

2003 rule, which would eliminate 

emissions of mercury. The commenter 

also stated that because the EPA is also 

responding to the 2004 petition for 

reconsideration in this rulemaking 

regarding whether eliminating mercury 

emissions is achievable, the EPA must 

either promulgate a zero-emissions 

standard or determine that such as 

standard is not achievable. The 

commenter added that under the CAA, 

the EPA cannot refuse to set such 

standards because it does not think they 

are ‘‘reasonable,’’ but it must set them 

at the maximum degree of reduction 

that is achievable. 

Response: We agree that it is 

technically achievable for facilities to 

switch from mercury cell to membrane 

cell technology, as there are many 

instances of successful switches 

spanning the last three decades. We also 

agree that it is technologically 

achievable, as a section 112(d)(2) and (3) 

beyond-floor measure, to require 

elimination of mercury emissions from 

the single remaining operating existing 

source. However, we disagree with the 

commenter’s assertion that the EPA 

must promulgate a standard solely 

based on technical achievability in the 

context of section 112(d)(6). Section 

112(d)(6) requires the EPA to review 

and revise emission standards as 

necessary, considering developments in 

practices, processes, or control 

technologies, but does not require 

revisions for all developments that are 

technically achievable. Other factors are 

considered, including cost, economic 

impacts, physical limitations of the site, 

etc. 

Nevertheless, based on consideration 

of public comments, and after 

reassessing the costs and feasibility of 

converting to the non-mercury 

technology, we have determined that 

the non-mercury option is technically 

and economically feasible and is cost 

effective and therefore reasonable to 

impose under both sections 112(d)(2) 

and (3) and (d)(6). As explained 

elsewhere in this preamble, we estimate 

the annualized costs to convert to a 

membrane process would be $2.7 

million per year (2019 dollars), with 

cost-effectiveness of $21,500 per pound 

of reduced mercury emissions. This cost 

effectiveness is within the range of cost 

effectiveness values the EPA has 

accepted historically for mercury 

reduction. For example, in the 2012 

Mercury and Air Toxics (MATS) final 

rule, the EPA finalized a beyond-thefloor standard for mercury with a cost 

effectiveness of $22,496 per pound 

(based on 2007 dollars), which would be 

approximately $27,500 per pound based 

on 2019 dollars. Furthermore, we 

conclude that conversion to a nonmercury process is clearly feasible, as 

demonstrated by the six mercury cell 

facilities in the U.S. that have converted 

to the non-mercury membrane process 

since the year 2000. Additionally, nonmercury chlorine production accounts 

for more than 98% of chlorine 

production in the U.S. 

Comment: One commenter 

maintained that the EPA’s vague 

characterizations of costs and its 

ignorance of current costs for the one 

remaining facility to switch to 

membrane technology did not constitute 

an excuse for failing to determine 

whether the measure is achievable. The 

commenter said that the Agency has had 

17 years since the 2004 petition for 

reconsideration to gather the data it 

needs, and any uncertainty about costs 

due to the EPA’s failure to gather the 

necessary data is not a lawful or 

reasonable basis for not setting a zeroemissions standard for mercury. 

Response: We disagree with the 

commenter’s characterization of our 

assessment of the costs of conversion. 

While the EPA did not commission a 

comprehensive detailed study to assess 

the costs specifically for the conversion 

of the West Virginia mercury cell chloralkali unit to convert to membrane cells, 

the EPA did update the previous 

analysis to incorporate new information 

to ensure that the estimated costs 

reflected ‘‘current’’ costs expected to be 

incurred for a conversion. The 

commenter did not mention or provide 

any specific comments on the updated 

analysis. 

The foundation for the analysis was 

the series of evaluations conducted by 

the EPA in 2008 through 2010, in 

support of the 2008 and 2011 proposed 

rules. The EPA first presented our 

evaluation of impacts of requiring 

conversion of all operating mercury cell 


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chlor-alkali production plants to nonmercury technology in 2008. Based on 

comments received after the June 11, 

2008, proposed amendments (73 FR 

33258), we updated this analysis and 

released it for public review in June 

2009. Comments were received on this 

revised analysis, and a second revision 

was released for public review in 

September 2009. The EPA received 

comments on this second revision of the 

analysis and issued another revision in 

April 2010. Therefore, the 2010 

analysis, which was based on extensive 

research by the EPA, had undergone 

three rounds of public review by the 

environmental community and the 

industry before it was relied upon to 

support the 2011 proposed rule. 

The 2020 update to the 2010 

conversion cost analysis involved 

several steps to ensure that the cost 

estimates were current. These included 

converting 2010 capital cost estimates, 

the savings associated with compliance 

with the mercury cell room monitoring 

program, and the electricity savings, to 

a 2019 base year. It also included 

incorporation of the reported costs of 

the latest conversion of a mercury cell 

facility in the U.S., which was the Ashta 

facility in Ohio that completed its 

conversion in late 2020. In addition, the 

2020 analysis considered the conversion 

cost estimate specifically provided for 

the West Virginia facility by the 

previous owner in public comments on 

the 2011 proposal and updated that 

estimate to base year 2019. 

Comment: One commenter (the owner 

of the single operating mercury cell 

facility) noted that the facility has not 

revisited the cost associated with 

converting to a non-mercury process 

since 2012, but they believe it is 

significantly higher than the EPA’s 

estimate of $69 million. 

Response: While the EPA recognizes 

that the facility may not have recently 

performed an update of the cost to 

convert their mercury cell unit to 

membrane technology, we believe there 

is sufficient information available to 

obtain a reasonable estimate of this cost. 

In our 2020 analysis, we estimated the 

conversion costs using three 

approaches. One was to base the capital 

cost of conversion solely on the highest 

cost factor (dollars per ton of chlorine 

production capacity) from the 

conversions considered in the 2010 

analysis (after adjusting to a 2019 base 

year). The second approach used the 

cost factor calculated from the reported 

cost for the most recent conversion at 

the Ashta facility in Ohio. The cost 

factor for this Ashta conversion was 

over 20 percent higher than the highest 

cost factor from the previous 

conversions after updating them to a 

2019 base year. The third approach was 

to incorporate the Ashta factor into an 

average of all the cost factors for 

conversions in the U.S. since 2003. 

These factors, which were in units of 

dollars per ton of chlorine production 

capacity, were then applied to the sitespecific production capacity of the West 

Virginia mercury cell unit. The resulting 

estimates of the capital cost of 

conversion of the West Virginia facility 

using these three approaches were 

approximately $76 million, $92 million, 

and $58 million, respectively (in 2019 

dollars). Given all the site-specific 

factors that are inherent in the cost of 

conversion, we do not believe it is 

appropriate to base an estimate on the 

factor from the conversion of a single 

facility. So, we did not select either of 

the first two options described above. 

We also did not want to potentially bias 

our estimate low, so we did not select 

the third option (average factor for five 

facilities that have converted since 

2003). Therefore, we calculated the 

average cost between the three options 

($69.3 million) and selected that average 

as our estimated cost of conversion for 

our consideration for our 2021 proposal. 

Considering the inflation that has 

occurred since 2019, the updated capital 

cost of conversion estimate is $80.7 

million (in 2021 dollars). Our 

confidence in this estimate was 

bolstered by a comparison of this result 

with the estimate that was specifically 

provided earlier in 2011 for the West 

Virginia facility by its previous owner. 

This estimate, when converted to 2019 

to be consistent with the year for our 

cost analysis, was $69.4 million (or 

$80.8 million for 2021 base year). Since 

the commenter did not provide any 

updated information in response to the 

2020 analysis and 2021 proposed rule, 

we continue to maintain that our 

estimate is a reasonable estimate of the 

capital costs of converting the West 

Virginia mercury cell unit to membrane 

cell technology. 

Comment: One commenter stated that 

the EPA’s proposal ignored the U.S. 

obligations under the Minamata 

Convention on Mercury, which is a 

global treaty that requires the phase-out 

of manufacturing processes using 

mercury. The commenter remarked that 

under Article 5(2), the phase-out date 

for chlor-alkali production using 

mercury is 2025, unless an exemption is 

filed. The commenter noted that an 

exemption was filed for these processes 

in the U.S., and the phase-out date is 

now 2030. According to the commenter, 

since companies are typically given 

three years to comply with MACT 

standards, a final rule requiring the 

phase-out of mercury would be required 

to be promulgated by the end of 2027 for 

the U.S. to meet its obligations under 

the Minamata Convention. The 

commenter stated that since a final rule 

in 2021 that does not require 

elimination of mercury would put the 

next 8-year review completion time at 

the end of 2029 at the earliest, the U.S. 

will then be out of compliance with the 

Minamata Convention. The commenter 

stated that the EPA must issue a new 

proposal explaining how the 2030 

phase-out deadline will be met. 

Response: We agree with the 

commenter’s summary of the U.S. 

obligations under the Minamata 

Convention agreement. We also agree 

that a NESHAP standard adopted under 

the authority of section 112 of the CAA 

is a valid approach to meet this 

obligation. In fact, during treaty 

negotiations, the U.S. specifically 

concluded that CAA section 112 gives 

the EPA the authority to require 

elimination of mercury emissions. We 

also agree with the commenter’s 

conclusions about the timing of when a 

NESHAP would need to be 

promulgated. Assuming a 3-year 

compliance timeframe would be needed 

for a final rule requirement that 

prohibits mercury emissions, a section 

112 NESHAP would need to either be 

finalized as part of this review, or a 

separate ‘‘out of cycle’’ review would be 

needed prior to 2027 to meet the current 

phase-out date of 2030 required under 

the Convention. (More information 

regarding the Minamata Convention is 

available at: https://

www.mercuryconvention.org/en/about). 

Comment: One commenter remarked 

that the environmental impacts the EPA 

cites as a reason not to require a zeroemission standard for mercury are 

actually environmental benefits. The 

commenter stated that the 1,000 pounds 

of mercury that are discharged to the 

environment every year would be 

eliminated. The commenter also stated 

that the EPA ignored the fact that 

mercury-contaminated piping and 

equipment must be removed at some 

point, and it is just a question of when. 

The commenter added that the costs of 

storing and moving mercury to a secure 

location is not a new expense, as the 

facility made a choice to continue 

operations with mercury past the date 

the Mercury Export Ban of 2008 (Pub. L. 

110–414) went into effect in 2013, and 

it determined at that point to assume 

those costs. 

Response: We estimate that the nonmercury requirement would eliminate 

just over 125 pounds of mercury 

released to the atmosphere per year. 


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Furthermore, at proposal we stated the 

following: ‘‘The EPA also examined the 

non-air impacts associated with 

switching from mercury cell to nonmercury cell processes. For 2019, the 

West Virginia facility reported a total of 

898.1 pounds of non-air mercury 

releases. This consists of 9 pounds to 

streams/water bodies, 883.3 pounds to 

Resource Conservation and Recovery 

Act, Subtitle C Landfills, and 5.8 

pounds to other offsite sources. All 

these releases would be eliminated with 

the conversion to non-mercury cell 

processes.’’ (86 FR 1382–1383) 

We also acknowledge the point made 

by the commenter regarding the costs 

associated with moving the mercury 

recovered from a conversion and storing 

it. Even without a regulatory 

requirement to eliminate mercury 

emissions from existing sources, the 

mercury cell unit would eventually 

reach the end of its useful life and be 

shut down or replaced. Since the 

standards for new and reconstructed 

sources in subpart IIIII prohibit mercury 

emissions, the owner or operator could 

not replace the unit with another 

mercury cell process. Even without this 

standard, which has been in place since 

2003, it is reasonable to assume that a 

new mercury cell facility would not be 

built. Prior to the promulgation of 

subpart IIIII, the use of the outdated 

mercury cell technology had been 

declining for decades and no new 

mercury cell facility had been 

constructed since the early 1970s. 

Hence, we agree that the owner most 

likely recognized this future cost when 

the decision was made not to convert 

prior to the effective date of the mercury 

export ban. Therefore, we conclude that 

the costs of the mercury storage should 

not be attributed to the non-mercury 

option under this rulemaking. 

The cost of this mercury storage was 

estimated to be just over $53,000 per 

year in our 2020 conversion cost 

analysis. Removing these mercury 

storage costs lowers the overall 

estimated annual cost, which includes 

the annualized capital cost, electricity 

savings and reduced compliance costs 

from $2.77 million to just over $2.7 

million. This improves the cost 

effectiveness from just over $22,000 per 

pound of mercury released to the air to 

around $21,500 per pound. In addition, 

as noted above, it also results in the 

reduction of around 900 pounds of 

mercury releases per year to other 

media. 

Comment: One commenter registered 

agreement with the EPA’s proposal to 

not require the elimination of mercury 

and stated that the NESHAP should not 

include a zero-mercury standard at this 

time. The commenter added that the 

single operating facility operates with 

low mercury emissions and pointed out 

that risks due to mercury are already 

low and at acceptable levels. However, 

another commenter expressed support 

for a zero-emission policy and a switch 

to non-mercury polluting processes at 

the West Virginia facility. This 

commenter stated that while the current 

mercury emissions may be in 

compliance with the 2003 NESHAP’s 

standards, effort should be made to 

increase sustainable industrial processes 

if possible. According to the commenter, 

considering the cost-benefit analysis, it 

would be more beneficial for the chloralkali plant to transition sooner rather 

than later because the plant will 

eventually have to transition or adopt a 

zero-mercury emission policy as our 

green infrastructure increases. The 

commenter added that when 

considering pollution, especially 

mercury, the goal should be zero, 

regardless of its economic impact. 

Additionally, the commenter supported 

policies that are more proactive in 

tackling pollution because accidents can 

happen and they’re typically more of an 

economic burden than taking proactive 

measures. Further, the commenter 

stated that even if the data shows no 

benefits to human health or the 

environment from further reducing the 

mercury emissions at the West Virginia 

plant, it would ultimately be one step 

closer to the national transition to 

cleaner, more sustainable industry. 

Response: As discussed above in 

section IV.A of this preamble, the first 

commenter is correct that our 

conclusion of the section 112(f) residual 

risk assessment was that health risks 

due to emissions of HAP from the 

Mercury Cell Chlor-Alkali Plants source 

category are acceptable, that the 2003 

NESHAP provides an ample margin of 

safety to protect public health, and that 

no additional standards are necessary to 

prevent an adverse environmental 

effect. While the recommendations of 

the second commenter generally lack 

any statutory authority to implement 

measures for a ‘‘green infrastructure’’ to 

‘‘transition to cleaner, more sustainable 

industry,’’ their point about a transition 

to zero mercury pollution is recognized. 

The residual risk assessment 

conducted under the authority of 

section 112(f) is focused on the local 

impacts (within 50km) directly resulting 

from HAP emissions from a NESHAP 

affected source. This type of assessment 

does not necessarily capture all the 

potential risks or impacts associated 

with mercury emissions. Mercury is a 

highly neurotoxic contaminant that 

enters the food web as a methylated 

compound, methylmercury. The 

contaminant is concentrated in higher 

trophic levels, including fish eaten by 

humans. Mercury is emitted to the air 

from various anthropogenic and natural 

sources. These emissions transport 

through the atmosphere and eventually 

deposit to land or water bodies. This 

deposition can occur locally, regionally, 

or globally, depending on the form of 

mercury emitted and other factors such 

as the weather. The form of mercury 

emitted from the single remaining 

operating plant is estimated to be about 

98 percent elemental and two percent 

divalent mercury. Gaseous elemental 

mercury can be transported very long 

distances, even globally, to regions far 

from the emissions source (becoming 

part of the global ‘‘pool’’) before 

deposition occurs. Inorganic ionic 

(divalent) mercury has a shorter 

atmospheric lifetime and can deposit to 

land or water bodies closer to the 

emissions source. Furthermore, 

elemental mercury in the atmosphere 

can undergo transformation into ionic 

mercury, providing a significant 

pathway for deposition of emitted 

elemental mercury (UNEP, Global 

Mercury Assessments, available at: 

https://www.unep.org/resources/ 

publication/global-mercury-assessment2018). 

Therefore, even though the estimated 

risks due to the mercury emissions are 

low based on our residual risk 

assessment, and the results of the 

residual risk assessment do not 

necessitate additional regulation to meet 

the requirements of CAA section 112(f), 

we agree that there is merit in 

eliminating mercury emissions where it 

is technically and economically feasible 

to do so, consistent with other statutory 

authority and requirements. And, as the 

second commenter points out, this is 

certainly possible in this situation, and 

the plant would need to ultimately 

eliminate mercury emissions anyway in 

order for the United States to meet its 

obligations under the Minamata 

Convention. 

4. What is the rationale for our final 

approach for the non-mercury option? 

As noted above, we are finalizing an 

amendment that prohibits mercury 

emissions from existing mercury cell 

chlor-alkali plants. Our rationale for this 

decision is based on the following 

points. First, our re-evaluation of the 

costs and associated emission 

reductions reveal that the cost 

effectiveness is within the range 

considered reasonable by the EPA for 

mercury and based on our economic 

analysis, the estimated annualized costs 

are only about 0.04 percent of the 


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2https://www.mercuryconvention.org/en/parties/ 

exemptions. 

annual revenue of the facility’s ultimate 

parent company in 2020 and therefore 

the amendment is reasonable as a 

beyond-floor standard under section 

112(d)(2) and (3). Second, this action 

will also eliminate the non-air releases 

that occur from the remaining mercury 

cell plant. Third, using the authority 

under section 112(d) of the CAA at this 

time is the most effective mechanism to 

ensure the U.S complies with the 

Minamata Convention agreement by the 

2030 deadline. Finally, as mentioned 

above, we conclude that conversion to 

a non-mercury process is clearly feasible 

and has been shown to be a 

development in practices, processes and 

control technologies under section 

112(d)(6), as demonstrated by six 

facilities in the U.S. that have converted 

to the non-mercury membrane process 

since the year 2000. Some of these 

points are discussed in more detail 

below. 

In response to a comment discussed 

above, we adjusted the annual costs to 

remove the mercury storage cost. This 

resulted in the cost effectiveness of the 

non-mercury option decreasing slightly 

to $21,500 per pound of mercury 

emission reduction. While this cost 

effectiveness is near the upper end of 

the range of cost effectiveness values the 

EPA has accepted historically for 

achievable mercury control, the EPA has 

previously determined that cost 

effectiveness values higher than this are 

acceptable and achievable. For example, 

in the 2012 MATS final rule, the EPA 

finalized a beyond-the-floor standard for 

mercury of $22,496 per pound (based on 

2007 dollars), which would be about 

$27,500 per pound based on 2019 

dollars. Therefore, we conclude that the 

cost effectiveness of $21,500 per pound 

of mercury emissions reduction is 

reasonable especially given the other 

factors described above, and we have 

decided to finalize the amendment to 

prohibit mercury emissions from 

existing sources as an achievable 

beyond-floor measure under section 

112(d)(2) and (3). 

As noted above, we evaluated the 

economic impacts of this amendment 

and determined that the impacts are not 

substantial, with the annualized costs 

being less than 0.04 percent of sales for 

the subject facility’s ultimate parent 

company (Westlake). We determined 

that the environmental benefit of the 

non-mercury option warranted these 

economic impacts. 

The primary reasons provided at 

proposal for discussing but not reproposing the non-mercury option were 

related to costs, cost effectiveness, and 

uncertainties. For example, in the 

January 2021 proposal FR document, 

the EPA stated that ‘‘first, mercury 

emissions are based on calculations and 

assumptions regarding the facility’s 

emissions (no test data are available for 

this facility), and second, because there 

are uncertainties with the cost estimates 

from the 2011 proposal as being 

transferable to the remaining facility. In 

the 2011 proposal, the estimated cost 

effectiveness was $20,000 per pound for 

the industry (see 76 FR 13852, March 

14, 2011), but this was substantially 

based on the studies conducted for the 

two no longer operating sources.’’ (86 

FR 1378–1379) 

While no additional emissions data 

based on testing was submitted in 

response to the 2021 proposal, we point 

out that subpart IIIII requires that 

measurements of the stack emissions be 

taken. The estimates reported by the 

West Virginia facility that were used in 

our analyses for fugitive emissions 

(121.4 pounds per year) are lower than 

the average level of 362 pounds per year 

per plant found during the extensive 

study conducted by the EPA prior to the 

2008 proposal (see description in the 

June 11, 2008, proposal at 73 FR 33263– 

33266). Therefore, if the confidence is 

lacking regarding these estimates, it is 

realistic to consider that emissions, and 

thus emission reductions, would likely 

only be higher. This would result in 

improved cost effectiveness values (i.e., 

the requirements would be more cost 

effective), providing further justification 

for our decision to finalize the nonmercury option. 

In the 2021 proposal we stated, 

‘‘Based on consideration of the updated 

costs and cost effectiveness and 

uncertainties, and given the passage of 

time, and the fact that the costeffectiveness data and analysis done in 

2011 were based on two facilities that 

are no longer operating, we question 

whether those 2011 analyses would still 

be transferable to the one remaining 

operating facility.’’ (86 FR 1378) Upon 

additional consideration, we have 

determined that this point is not 

relevant to the decision regarding the 

cost effectiveness of a non-mercury 

standard for the West Virginia facility. 

In 2011, we calculated an average cost 

effectiveness for the conversion of the 

four mercury cell facilities operating at 

that time. The range was between 

$13,000 to $31,000 per pound for the 

four individual facilities. However, the 

estimated cost effectiveness values for 

the two facilities that closed prior to 

2020 is not determinative of the 

estimate of the conversion cost for the 

West Virginia facility. Also, the cost 

effectiveness for these two facilities 

does not compel what the EPA 

considers a reasonable cost effectiveness 

level for mercury. Therefore, we now 

reject the two major points used as 

rationale in the 2021 proposal for not 

accepting and proposing the nonmercury option. We are confident that 

the mercury emissions estimates for the 

West Virginia facility are reliable and, if 

anything, are underestimated. We also 

have determined that the cost estimate 

is reasonable and applicable and could 

be even more cost effective than 

presented here due to potential 

underestimation of the emissions. 

Consequently, the non-mercury option 

is a reasonable beyond-floor measure 

under section 112(d)(2) and (3), and the 

fact that six mercury cell facilities have 

converted to non-mercury membrane 

technology since 2000 and only a single 

mercury cell source remains at a facility 

that already has two non-mercury 

chlorine production units shows that is 

necessary to revise our existing source 

standard to take into account 

developments in practices, processes 

and control technologies. 

Regarding the Minamata Convention 

on Mercury, this is a global treaty to 

protect human health and the 

environment from the adverse effects of 

mercury. It was agreed at the fifth 

session of the Intergovernmental 

Negotiating Committee on mercury in 

Geneva, Switzerland on January 19, 

2013, and adopted later that year on 

October 10. The Minamata Convention 

entered into force on August 16, 2017. 

Major highlights of the Minamata 

Convention include a ban on new 

mercury mines, the phase-out of 

existing ones, the phase out and phase 

down of mercury use in a number of 

products and processes, control 

measures on emissions to air and on 

releases to land and water, and the 

regulation of the informal sector of 

artisanal and small-scale gold mining. 

The Convention also addresses interim 

storage of mercury and its disposal once 

it becomes waste, sites contaminated by 

mercury, and health issues. 

Under the Minamata Convention, the 

U.S. has specifically addressed mercury 

cell chlor-alkali production. For 

example, in the registration for an 

extension of the mercury phase out 

deadline from 2025 to 2030, the U.S. 

stated the following: 

‘‘Pursuant to Article 6, paragraph 1 of 

the Minamata Convention on Mercury, 

the United States hereby registers for an 

exemption from the phase-out date 

listed in Annex B for the use of mercury 

in chlor-alkali production.’’ 2 The 

United States also provides the 


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3 Ibid. 

following statement explaining the need 

for the exemption: 

‘‘The United States supports the 

phase-out of mercury use in chlor-alkali 

production facilities. It has 

implemented domestic strategies to 

encourage a timely transition to 

mercury-free alternative technologies 

with a view to phasing out all mercury 

use in domestic chlor-alkali production 

facilities. New or reconstructed chloralkali production facilities in the United 

States are already effectively prohibited 

from using mercury under section 112 

of the Clean Air Act. See 40 CFR 

63.8190. Most mercury cell chlor-alkali 

facilities in the United States have 

already closed or converted. While there 

were 14 such facilities in 1998, only two 

remained as of late 2013. The United 

States will, pursuant to Article 6, 

paragraph 7, withdraw this exemption if 

that becomes possible prior to its 

expiration date.’’ 3

Therefore, the U.S. is committed to 

phasing out all mercury emissions in 

domestic chlor-alkali facilities by 2030. 

The EPA is not aware of any plans by 

the owner of the lone remaining 

mercury cell chlor-alkali facility in West 

Virginia to close or convert their 

mercury cell facility before 2030. 

Therefore, we have determined that it is 

necessary to require this action to 

ensure the facility converts or closes the 

mercury cell chlor-alkali production 

process in order to eliminate mercury 

emissions and section 112 of the CAA 

provides an appropriate regulatory 

mechanism to enact such a requirement 

to eliminate emissions. The two main 

options regarding timing are: (1) 

Promulgate a non-mercury standard at 

this time under section 112(d)(2) and (3) 

and/or section 112(d)(6); or (2) 

promulgate a non-mercury standard by 

fall 2027 (i.e., before the next 8-year 

cycle for a technology review required 

by section 112(d)(6)). 

As pointed out by commenters, the 

next 8-year review will not be required 

until 2030. If a non-mercury standard 

was promulgated in 2030 and included 

the 3-year compliance date allowed by 

CAA section 112, the phase-out would 

not occur in time to comply with the 

2030 deadline. We do not think it is 

prudent to plan a separate ‘‘out of 

cycle’’ review to promulgate a nonmercury standard in 2027, especially 

since the review shows that the nonmercury standard is technologically 

feasible, cost effective and will not 

impose significant economic impacts at 

this time, and there is no reason to think 

a decision would be any different in 

2027. Therefore, we concluded that the 

best option to ensure compliance with 

the Minamata Convention is to 

promulgate a non-mercury standard at 

this time. 

We recognize that we did not 

specifically propose this option in the 

January 2021 proposal. However, we did 

include it as an option that was 

considered and described it in detail, 

we provided our analysis of this option 

and specifically requested comment on 

the option. Specifically, we stated the 

following: 

‘‘However, we are soliciting 

comments, data, and other information 

regarding these proposed decisions, 

including data and information 

regarding the costs, cost effectiveness, 

non-air, and economic impacts and 

other relevant information regarding 

whether the NESHAP should include a 

non-mercury standard as either a 

beyond-the-floor MACT standard or a 

revised standard under the technology 

review, and whether the proposed work 

practices for chlorine emissions and 

proposed amendments to the mercury 

work practices would be necessary if a 

non-mercury standard were to be 

adopted.’’ 

EPA also stated that ‘‘We intend to 

consider any such submitted data and 

information, in addition to the data and 

information contained in the records for 

the 2008 and 2011 proposals and in this 

proposal, in reaching final conclusions 

under CAA sections 112(d)(2) and (6) 

regarding a non-mercury standard.’’ (86 

FR 1383) 

Furthermore, the EPA proposed the 

non-mercury option in 2011 and 

referred to this 2011 proposal in the 

January 2021 FR document. Therefore, 

we provided sufficient notice of the 

potential that we would finalize a nonmercury option, and we are finalizing 

the non-mercury requirement based on 

a logical outgrowth of comments on our 

proposal and the record that public 

commenters had an opportunity to 

review and address. 

C. Technology Review for the Mercury 

Cell Chlor-Alkali Plants Source Category 

1. What did we propose pursuant to 

CAA section 112(d)(6) for the Mercury 

Cell Chlor-Alkali Plants source 

category? 

Pursuant to CAA section 112(d)(6), we 

proposed amendments to the rule that 

would have required the combination of 

both a cell room monitoring program to 

continuously monitor mercury vapor in 

the cell room and a suite of equipment 

standards and work practices to reduce 

fugitive mercury emissions. This is 

different from the NESHAP promulgated 

in 2003, which required either the 

equipment standards and work practices 

or the cell room monitoring program. As 

described above, we also evaluated the 

non-mercury option under our section 

112(d)(6) technology review. 

2. How did the technology review 

change for the Mercury Cell ChlorAlkali Plants source category? 

As discussed above in section IV.B, 

we changed our decision related to the 

non-mercury option and are 

promulgating a prohibition of mercury 

emissions from the source category. The 

result of this final amendment 

prohibiting mercury emissions will be 

that there will no longer be any 

operating mercury cell chlor-alkali 

plants in the U.S. after May 6, 2025. 

3. What key comments did we receive 

on the technology review, and what are 

our responses? 

The only comment received on our 

proposed technology review, other than 

those related to the non-mercury option 

discussed above in section IV.B.3, was 

one from the facility that clarified that 

the existing continuous monitor 

analyzers for mercury at the facility are 

capable of detecting mercury 

concentration of 0.1 mg/m3, which 

would meet the EPA’s proposed 

detection requirements. 

4. What is the rationale for our final 

approach for the technology review? 

The rationale for our final decision 

regarding the non-mercury option is 

discussed above in section IV.B.4. 

Regarding the cell room monitoring 

program and equipment and work 

practice standards to reduce fugitive 

mercury emissions, the facility complies 

with the fugitive mercury standards by 

operating a continuous cell room 

monitoring program in accordance with 

paragraph 63.8192(g) as an alternative to 

the equipment standards and work 

practices in paragraphs 63.8192(a) 

through (d). However, while not 

required to do so under the NESHAP 

promulgated in 2003, the facility also 

implements those equipment standards 

and work practices. Therefore, the EPA 

determined that the combination of 

implementing a cell room monitoring 

program and performing work practices 

constitutes a development in emissions 

control practices and is finalizing the 

proposed requirement that both a cell 

room monitoring program and 

equipment and work practices be 

implemented during the period of up to 

3 years before the facility converts the 

mercury cell process to a non-mercury 

process or closes the mercury cell 

process. 


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D. Amendments Pursuant to Sections 

112(d)(2) and (3) and (h) for the Mercury 

Cell Chlor-Alkali Plants Source Category 

1. What did we propose pursuant to 

CAA section 112(d)(2) and (3) and (h) 

for the Mercury Cell Chlor-Alkali Plants 

source category? 

Pursuant to CAA sections 112(d)(2) 

and (3) and (h), in 2021 we proposed 

amendments to the rule that would have 

required a leak detection and repair 

program to identify chlorine equipment 

leaks in the cell room and throughout 

the other parts of the mercury cell chloralkali production facility affected source 

that handle and process the chlorine gas 

produced. The proposed rule would 

have also required that chlorine 

monitors be installed and operated 

continuously throughout the affected 

source and that each time one of these 

sensors measured a chlorine 

concentration of 2 ppmv or greater, a 

complete inspection for leaks of all 

equipment containing 5 percent 

chlorine by volume would have been 

required within 1 hour of detection. 

In addition, we evaluated the beyondthe-floor non-mercury option under our 

consideration of section 112(d)(2) and 

(3); however, we did not propose the 

non-mercury standard in the January 8, 

2021 proposal. 

2. How did the decision related to CAA 

section 112(d)(2) and (3) change for the 

Mercury Cell Chlor-Alkali Plants source 

category? 

As discussed above in section IV.B, 

we changed our decision related to the 

non-mercury option and are 

promulgating a prohibition of mercury 

emissions from the source category. The 

result of this final amendment 

prohibiting mercury emissions will be 

that there will no longer be any 

operating mercury cell chlor-alkali 

plants in the U.S. after May 6, 2025. 

3. What key comments did we receive 

on our proposed decision related to 

CAA sections 112(d)(2) and (3) and (h), 

and what are our responses? 

As discussed above in section IV.B.3, 

comments were received regarding the 

proposed determination not to require 

the non-mercury option as a beyondthe-floor requirement. Comments were 

also received related to the proposed 

fugitive chlorine requirements. In 

addition, comments were received 

claiming that standards should have 

been proposed for emissions of HCl. 

These comments, along with responses 

from the EPA, are provided below in 

this section. 

Comment: The single operating 

facility provided several comments 

regarding the proposed requirements to 

reduce chlorine emissions. While they 

corrected the EPA’s assumption that the 

cell room was under negative pressure, 

they noted that most of the equipment 

containing chlorine gas is under 

negative pressure, which would be 

excluded from the proposed leak 

detection requirements. They noted that 

the facility already complies with most 

of the proposed fugitive chlorine 

requirements, and they explained how 

they would comply with the additional 

requirements. They agreed that the 

proposed olfactory observations are 

appropriate versus visual or auditory 

inspections, due to the low odor 

threshold of chlorine. They did, 

however, register concern about the 

chlorine leak repair requirements, 

noting that final repairs to leaks from 

some causes may take more than one 

day to complete, as required in the 

proposal. They also provided responses 

to the EPA’s requests for comments 

regarding the proposed requirements for 

continuous chlorine sensors and the 

proposed 2 parts per million by volume 

(ppmv) action level and averaging time. 

In response to the EPA’s request for 

comment regarding whether the EPA 

should specify sensor placement 

locations, they expressed concern about 

placing chlorine sensors in the cell 

room, as they stated that the high 

magnetic field in the cell room has 

historically caused unreliable 

transmitter responses. They indicated 

that, if the EPA finalized a requirement 

to place chlorine sensors in the cell 

room, additional time would be needed 

to comply with the standard, as the 

facility would need to evaluate whether 

the use of a chlorine sensor(s) in the cell 

room is technically feasible and, if 

feasible, to procure and install the 

sensors. 

Response: The EPA appreciates the 

effort provided by the commenter to 

carefully review the proposed fugitive 

chlorine requirements, to provide 

thoughtful comments, and to put forth 

preliminary ideas on how they would 

comply. We also appreciate the 

concerns raised about the repair timing 

requirement and the placement of 

chlorine sensors in the cell room. Based 

on these comments, we have revised the 

final requirements to add time to make 

repairs, which would allow time to 

obtain equipment that is not kept onsite, 

by increasing the time for final repairs 

to be made from 24 to 72 hours. Further, 

based on these comments and the 

technical feasibility of placing sensors 

in certain locations, we have not added 

requirements stipulating sensor 

locations in the final rule. Finally, we 

agree that an action level for equipment 

inspections based on a single sensor 

reading may not be indicative of a 

problem that warrants special 

investigation. Accordingly, we have 

revised the action level that triggers an 

inspection of all chlorine-containing 

equipment to be detection by a sensor 

of a one-hour average chlorine 

concentration of 2 ppmv or greater. 

Comment: One commenter stated that 

the EPA must set emissions standards 

for HCl. The commenter contended that 

even if the HCl emissions are from 

direct synthesis HCl production units, 

these units are part of the mercury cell 

chlor-alkali plant and must be regulated. 

The commenter stated that these units 

would be affected sources because they 

are ‘‘cell rooms and ancillary operations 

used in the manufacture of product 

chlorine, product caustic, and byproduct hydrogen at a plant site’’ and 

‘‘processes and associated operations 

needed for mercury recovery from 

wastes at a plant site.’’ 

Response: We disagree with the 

commenter’s rationale of why the direct 

synthesis HCl production units would 

be part of an affected source under 

subpart IIIII. They are not part of the cell 

room or the ancillary operations used in 

the manufacture of product chlorine, 

product caustic, or by-production 

hydrogen. In fact, the HCl production 

units are downstream operations from 

the chlor-alkali process, as they use the 

product chlorine and by-product 

hydrogen to create HCl. Additionally, 

these units are not associated with the 

processes needed for the recovery of 

mercury. 

While not cited by the commenter, the 

EPA has previously considered direct 

synthesis HCl units co-located with 

chlor-alkali plants to be part of the 

chlor-alkali plant. In the July 3, 2002, 

proposal for the chlorine production 

source category, the EPA stated ‘‘Since 

chlor-alkali processes produce both 

chlorine and hydrogen, it is common for 

a direct synthesis HCl production unit 

to be incorporated into a chlor-alkali 

facility. Therefore, we consider these 

direct synthesis HCl production units to 

be a part of the chlor-alkali facilities.’’ 

(67 FR 44713). The HCl (and chlorine) 

emissions from the co-located direct 

synthesis HCl plants were included in 

the risk assessment that led to the EPA’s 

decision in 2003 not to develop any 

NESHAP for non-mercury cell chloralkali plants and to delete the nonmercury subcategory. Further, because 

these units were considered part of the 

deleted non-mercury cell chlorine 

production subcategory, they were 

specifically exempted from the HCl 


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NESHAP, 40 CFR subpart NNNNN, at 

63.8985(d). 

At the West Virginia facility, there are 

three chlor-alkali units: The mercury 

cell unit and two diaphragm cell units. 

According to the air permit for the 

facility, the diaphragm cell units 

produce approximately four times as 

much chlorine as the mercury cell unit. 

Therefore, if the HCl production units 

were assigned to one of the chlorine 

production subcategories based on the 

contribution of the chlorine and 

hydrogen contributed, they would be 

considered part of the non-mercury cell 

subcategory of chlor-alkali plants. In 

addition, when the EPA finalized the 

decision to delete the non-mercury 

subcategory on December 19, 2003, we 

stated ‘‘we have clarified that chlorine 

and HCl emissions from the absorber 

vents of direct synthesis HCl production 

units at chlor-alkali facilities, as well as 

the associated storage tanks and transfer 

operations specified above, are included 

in the non-mercury cell chlorine 

production subcategory . . .’’ (68 FR 

70948) 

As shown through this cited history, 

the EPA has clearly established that HCl 

direct synthesis units are not part of the 

mercury cell chlor-alkali source 

category, and we are not pursuing their 

regulation under subpart IIIII. 

Comment: One commenter stated that 

the EPA proposed to limit the 

applicability of the rule with changes to 

–63.8182, –63.8184(a) and definitions in 

–62.8266. The commenter asserted that 

the EPA did not provide any 

explanation or justification for these 

proposed changes, which is a violation 

of the CAA and makes it impossible to 

determine what the EPA is intending to 

accomplish. The commenter’s 

interpretation was that the EPA was 

changing the existing regulation to 

avoid regulating HCl emissions from the 

plant. The commenter stated that if that 

is the case, the EPA is acting unlawfully 

by attempting to bypass its statutory 

obligations to regulate all HAP and HAP 

emission points within a source 

category. 

Response: The commenter is correct 

that these changes were not explained 

in the January 2021 proposal. They were 

changes that were proposed in both the 

2008 proposal and the 2011 

supplemental proposal, with the 

purpose of ensuring that a mercury 

thermal recovery unit affected source at 

a site where the mercury cell production 

facility was either converted or closed 

would continue to be subject to the 

emission limitations while processing 

the wastes from the closed mercury cell 

plant. Since the single remaining 

mercury cell chlor-alkali plant does not 

have a thermal mercury recovery unit, 

these changes are not necessary and 

should not have been included. They 

are in no way related to HCl emissions 

from the plant. In fact, as noted above, 

these amendments were holdovers from 

the 2008 proposal and the 2011 

supplemental proposal when only 

mercury emissions were under 

consideration. 

4. What is the rationale for our final 

approach for the CAA sections 112(d)(2) 

and (3) and (h)? 

The rationale for our final decision 

regarding the non-mercury option is 

discussed above in section IV.B.4. For 

the fugitive chlorine work practices, the 

facility voluntarily implements work 

practices that are consistent with the 

proposed requirements and represents 

the MACT floor. As these chlorine 

emissions are fugitive in nature 

resulting from potential equipment 

leaks, they cannot be emitted through a 

conveyance designed and constructed to 

emit or capture such pollutant or 

measured. Therefore, we are finalizing 

the proposed amendments requiring 

work practices to minimize chlorine 

emissions. Further, as discussed above, 

we are not developing standards under 

section 112(d)(2) and (3) for the HCl 

emissions from the direct synthesis HCl 

production units at the West Virginia 

site. 

E. Amendments addressing emissions 

during periods of startup, shutdown, 

and malfunction and other topics? 

1. What did we propose related to 

emissions during periods of startup, 

shutdown, and malfunction and other 

topics? 

We proposed revisions related to 

emissions during periods of startup, 

shutdown, and malfunction (SSM); 

provisions for electronic submission of 

performance test results, performance 

evaluation reports, and Notification of 

Compliance Status (NOCS) reports; and 

corrections of various errors in 

compliance provisions in the NESHAP. 

2. How did the decision related to 

emissions during periods of startup, 

shutdown, and malfunction and other 

topics change? 

No changes have been made regarding 

our decisions concerning periods of 

SSM and the corrections of various 

compliance provisions in the current 

rule. For submission of performance test 

results, performance evaluation reports, 

and Notification of Compliance Status 

(NOCS) reports, we have determined it 

is necessary for the facility to switch to 

electronic reporting, considering the 

timing of the final non-mercury 

emission standard and related 

upcoming closure or conversion of the 

one remaining mercury cell chlor-alkali 

unit. 

3. What key comments did we receive 

on proposed decision related to 

emissions during periods of startup, 

shutdown, and malfunction and other 

topics? 

Comment: One commenter relayed 

several concerns regarding the proposed 

startup, shutdown, and malfunction 

provisions. According to the 

commenter, higher mercury emissions 

may occur during startup due to the 

hydrogen vent system and its control 

device, which will cause compliance 

concerns until alternative work 

practices can be developed to reduce 

emissions from this system. The 

commenter stated, at the time they 

submitted public comments, that the 

control device cannot be operated until 

the exhaust stream composition can be 

regulated, and the facility would need 

additional time to evaluate operational 

methods to improve operation of the 

control device. The commenter added 

that additional time would also be 

needed to determine the modifications 

necessary to reduce emissions during 

startup, to develop and implement a 

recordkeeping system, and perform 

operator training. The commenter 

requested a time frame of 12 months 

rather than 6 months for compliance 

with all the proposed SSM 

requirements. 

Response: To understand the 

commenter’s concerns better and to 

determine whether a different standard 

was needed for startup periods, the EPA 

had a teleconference meeting with the 

commenter to discuss the issue. During 

this discussion, the commenter 

indicated that the facility had found a 

way to comply with the emissions 

standards at all times, including startup. 

The notes of the meeting are in the 

docket for this rulemaking (EPA–HQ– 

OAR–2020–0560). Therefore, with the 

issue resolved, the EPA is finalizing the 

proposed requirements that the 

emissions limits apply at all times and 

no separate requirements are necessary 

for periods of startup, and further, no 

additional time is necessary or provided 

for compliance. 

Comment: One commenter supported 

electronic reporting in general but stated 

a preference to submit any such 

information in PDF format. 

Response: Given that the facility 

could operate for up to 3 more years 

before it converts to a non-mercury 

process or shut down, we have decided 


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to require the facility to switch to 

electronic reporting. 

Comment: One commenter noted that 

the EPA proposed to add a performance 

testing requirement at 40 CFR 

63.8232(a). The commenter believes that 

the annual calibration testing at the 

facility satisfies the requirements of a 

performance test, and additional 

performance testing is not needed. 

Response: The commenter 

misinterpreted the proposed changes to 

40 CFR 63.8323(a), which did not add 

a new performance testing requirement. 

Rather, these proposed changes clarified 

the conditions under which the 

performance test must be conducted. 

These changes establish that 

performance tests must be conducted 

during normal operations and remove a 

reference to 40 CFR 63.7(e)(1), which 

conflicts with the requirement to 

comply with the standards at all times, 

including during periods of SSM. As 

these requirements are simply clarifying 

performance test conditions and 

ensuring the standards are met at all 

times, we are finalizing the revised 

provisions as proposed. 

4. What is the rationale for our final 

approach for requirements related to 

emissions during periods of startup, 

shutdown, and malfunction and other 

topics? 

The rationale for our final decision 

regarding the non-mercury option is 

discussed above in section IV.B.4. As 

discussed in the responses in the 

previous section, we are finalizing the 

proposed electronic reporting 

amendments for the reasons described 

above. Furthermore, we have not 

changed our final approach to the 

requirements for periods of SSM, and 

we are finalizing these requirements as 

proposed based on the considerations 

described above. 

F. Public Notice and Comments 

In addition to the comments on the 

proposal, one commenter objected to the 

EPA’s decision not to publish the 

proposed rule amendments in the 

Federal Register. 

Comment: The commenter observed 

that the EPA proposed significant 

changes to the regulatory language, but 

these changes were not in the EPA’s 

proposed rule. The commenter 

remarked that the CAA and the 

Administrative Procedures Act (APA) 

both make plain that proposed rules 

must be published in the Federal 

Register (42 U.S.C. 7607(d)(3); 5 U.S.C. 

553(b)). Further, the commenter stated 

that the CAA requires the EPA to 

include a summary of the major legal 

interpretations and policy 

considerations underlying its proposed 

rules, and the EPA did not provide this 

explanation nor any explanation for its 

proposed changes to the regulatory text. 

The commenter states that if the EPA 

wishes to make changes to the Code of 

Federal Regulations, it must withdraw 

this proposal, publish the proposed 

changes in the Federal Register and 

provide a new opportunity for public 

comment. 

Response: The proposal met all APA 

and CAA notice and comment 

requirements. Nothing in the APA or the 

CAA, including the language the 

commenter cites, requires the EPA to 

publish proposed rule text in the 

Federal Register. The commenter 

suggests that because the EPA did not 

publish the proposed rule text, the EPA 

failed to meet the CAA 307(d)(3) 

requirement to publish a ‘‘notice of 

proposed rulemaking.’’ However, the 

requirement to publish a ‘‘notice of 

proposed rulemaking’’ is not a 

requirement to publish ‘‘proposed rule 

text.’’ Section 307(d)(3) specifies the 

required elements of a ‘‘notice of 

proposed rulemaking’’ and ‘‘proposed 

rule text’’ is not a required element. The 

elements the commenter cites that are 

required to be included in the notice of 

proposed rulemaking (a ‘‘statement of 

basis and purpose,’’ ‘‘a summary of . . . 

the major legal interpretations and 

policy considerations underlying the 

proposed rule, etc. . .’’) were included, 

and commenter does not suggest 

otherwise. 

The APA does not require publication 

of proposed rule text in the Federal 

Register either. Section 553(b)(3) of the 

APA provides that a notice of proposed 

rulemaking shall include ‘‘either the 

terms or substance of the proposed rule 

or a description of the subjects and 

issues involved.’’ (emphases added). 

Thus, the APA clearly provides 

flexibility to describe the ‘‘subjects and 

issues involved’’ as an alternative to 

inclusion of the ‘‘terms or substance’’ of 

the proposed rule. See also Rybachek v. 

U.S. E.P.A., 904 F.2d 1276, 1287 (9th 

Cir. 1990). (The EPA’s failure to propose 

in advance the actual wording of a 

regulation does not make the regulation 

invalid where the EPA’s discussion of 

the regulatory provisions ‘‘clearly 

describe ‘the subjects and issues 

involved.’ ’’). 

The commenter claims that the EPA 

did not publish ‘‘any explanation for its 

proposed changes’’. However, the 

commenter does not identify any 

specific regulatory text that was not 

explained or specify any deficiency in 

any explanation of regulatory text in the 

Federal Register document. Such a 

generalized objection is not sufficiently 

specific. See, e.g., Appalachian Power 

Co. v. E.P.A., 251 F.3d 1026, 1036 (D.C. 

Cir. 2001) (‘‘ ‘An objection must be made 

with sufficient specificity reasonably to 

alert the agency.’ ’’ (quoting Tex Tin 

Corp. v. EPA, 935 F.2d 1321, 1323 (D.C. 

Cir. 1991)). 

The commenter makes a vague 

assertion that the EPA’s approach was 

prejudicial to the ability of the public to 

be able to find and comment on the 

proposed regulatory changes but does 

not claim any actual difficulty in 

finding or commenting on the proposed 

rule language. The EPA approach was 

not prejudicial to the commenter or any 

member of the public. The notice of 

proposed rulemaking clearly explained 

that the proposed amendatory language 

and a redline strikeout version of the 

subpart IIIII showing proposed changes 

were available in the docket and on 

EPA’s website: https://www.epa.gov/ 

stationary-sources-air-pollution/ 

mercury-cell-chloralkali-plantsnational-emissions-standards. 

The proposed changes to the CFR that 

would be necessary to incorporate the 

changes proposed in this action are set 

out in an attachment to the 

memorandum titled Proposed 

Regulation Edits for 40 CFR part 63, 

subpart IIIII, available in the docket for 

this action (EPA–HQ–OAR–2020–0560). 

The document includes the specific 

proposed amendatory language for 

revising the CFR and, for the 

convenience of interested parties, a 

redline version of the regulation. 

Although the EPA’s recent practice 

has generally been to publish proposed 

amendatory regulatory text, the EPA’s 

practice has varied. See, e.g., Hazardous 

Air Pollutants: Proposed Regulations 

Governing Constructed, Reconstructed 

or Modified Major Sources, 59 FR 15504 

(April 1, 1994) (‘‘The proposed 

regulatory text is not included in the 

Federal Register document, but is 

available in Docket No. A–91–64 or by 

request from the EPA contact persons 

designated earlier in this note. The 

proposed regulatory language is also 

available on the technology Transfer 

Network (TTN), of EPA’s electronic 

bulletin boards.’’); Federal Standards for 

Marine Tank Vessel Loading and 

Unloading Operations and National 

Emission Standards for Hazardous Air 

Pollutants for Marine Tank Vessel 

Loading and Unloading Operations, 59 

FR 25004 (May 13, 1994) (‘‘The 

proposed regulatory text and other 

materials related to this rulemaking are 

available for review in the docket.’’). 

And even when we do include the 

proposed text in the Federal Register, 

we often include a redline version of 

proposed regulations in the docket for 


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4National Emission Standards for Hazardous Air 

Pollutants: Coal- and Oil-Fired Electric Utility 

Steam Generating Units—Revocation of the 2020 

Reconsideration, and Affirmation of the 

Appropriate and Necessary Supplemental Finding; 

Notice of Proposed Rulemaking (87 FR 7624, 

February 9, 2022). 

rulemakings to assist the public in 

understanding the proposed regulatory 

changes. In our experience, stakeholders 

find the redline version far more useful 

than the proposed amendatory language 

in the format required by the Office of 

the Federal Register. Although 

appropriate for the task of revising the 

Code of Federal Regulations, this 

language can be difficult to assess 

without the accompanying full 

regulatory text. Given this and given 

that we rarely receive comments on the 

proposed amendatory language or on 

proposed regulatory language at all, we 

determined that for rulemakings such as 

these, it would be more efficient to take 

the approach here of making both easily 

accessible but not including the 

proposed amendatory text in the 

document. 

V. Summary of Cost, Environmental, 

and Economic Impacts and Additional 

Analyses Conducted 

A. What are the affected facilities? 

There is one facility affected by this 

action, which is the one remaining 

mercury cell chlor-alkali facility 

operating in the U.S. This facility is 

located in West Virginia. 

B. What are the air quality and other 

environmental impacts? 

The air quality impacts of this final 

action will be the elimination of 

approximately 125 pounds of mercury 

emissions annually. In addition to this 

air quality impact, this action will result 

in the elimination of around 900 pounds 

of mercury that are released annually to 

other media. 

In addition, it is estimated that the 

conversion of the remaining mercury 

cell facility to membrane cells will 

result in an energy savings of around 25 

percent which results in an estimated 

cost savings of around $1.5 million per 

year. 

C. What are the cost impacts? 

The capital cost of complying with 

the promulgation of the non-mercury 

requirement is estimated to be $69.4 

million if the facility chooses to convert 

its mercury unit to a non-mercury 

process rather than rely on its two 

existing non-mercury units. The total 

estimated annual costs, including the 

annualized capital costs minus the 

savings realized from the lower 

electricity needs and the savings related 

to the elimination of the burden of the 

environmental regulations associated 

with mercury, are $2.7 million per year 

in 2019 dollars. Table 3 presents the 

estimated annual cost components for 

conversion from mercury cell to 

membrane cell technology. 

TABLE 3—TOTAL ANNUAL COST OF

CONVERSION OF THE WEST VIRGINIA

MERCURY CELLS TO MEMBRANE

CELLS

[2019$] 

Annual cost component Annual cost 

($/yr) 

Capital Recovery .................. $4,764,982 

Mercury Storage ................... 53,364 

Compliance Savings ............. ¥546,572 

Electricity Savings ................ ¥1,504,893 

Total Annual .................. 2,766,880 

D. What are the economic impacts? 

The net present value of the estimated 

cost impacts of the final amendments to 

the Mercury Cell Chlor-Alkali NESHAP 

is $43.0 million, discounted at a 7 

percent rate to 2020 over a 20-year 

analytic time frame from 2021 to 2040 

in 2019 dollars. Using a 3 percent 

discount rate, the net present value of 

the estimated cost impacts is $39.4 

million. The equivalent annualized 

value, which is a measure of the 

annualized costs of the final rule 

consistent with the net present value, is 

$4.0 million and $2.6 million for 7 and 

3 percent discount rates respectively. 

As stated previously in section B.3., 

the estimated total annual costs are $2.7 

million for the Westlake facility. Based 

on our analysis, the estimated 

annualized costs are only about 0.04 

percent of the annual revenue of the 

facility’s ultimate parent company in 

2020. Since the estimated cost impacts 

are minimal, no significant economic 

impacts to the ultimate parent company 

nor its consumers are anticipated due to 

the final amendments. For additional 

details on the economic impact analysis 

please see the memorandum entitled 

Economic Impact Analysis for the Final 

Mercury Cell Chlor-Alkali National 

Emission Standard for Hazardous Air 

Pollutants (NESHAP) Beyond-Floor 

Determination and Risk and Technology 

Review (RTR) available in the docket 

(EPA–HQ–OAR–2020–0560). 

E. What are the benefits? 

The EPA anticipates a complete 

elimination of mercury emissions at the 

one remaining mercury cell chlor-alkali 

plant as a result of the final 

amendments to the Mercury Cell ChlorAlkali Plants NESHAP. This is 

estimated to be a reduction of 125 

pounds of mercury emitted to the 

atmosphere annually and approximately 

900 pounds of mercury released 

annually to other media. EPA has not 

monetized the health benefits of 

reduced mercury emissions due to this 

rulemaking due to the lack of site 

specific data and insufficient economic 

research to support the valuation of the 

health impacts often associated with 

exposure to individual HAP. For the 

2022 proposed rule for the Mercury Air 

Toxics Standard (MATS) EPA did 

develop bounding estimates for the risk 

and associated dollar valuation 

associated with mercury emitted from 

U.S. Electric Utility Steam Generating 

Units. These estimates focused on 

exposure of the general population to 

methylmercury through commercial fish 

consumption and included IQ loss for 

children exposed in-vitro and adult 

myocardial infarction (MI)-related 

mortality. These bounding estimates are 

subject to uncertainty which is 

discussed in the rule language.4 While 

the risk assessment conducted for the 

RTR indicates that risks from the source 

category are already low, future risks 

from this source category will be 

reduced to zero. Furthermore, as 

described above, this action will 

eliminate the releases of mercury to the 

global pool from this source. 

F. What analysis of environmental 

justice did we conduct? 

Consistent with EPA’s commitment to 

integrating environmental justice (EJ) in 

the agency’s actions, and following the 

directives set forth in multiple 

Executive Orders, the Agency has 

carefully considered the impacts of this 

action on communities with EJ 

concerns. For this action, we performed 

a demographic analysis, which is an 

assessment of risks to individual 

demographic groups of the populations 

living within 5 kilometers (km) and 

within 50 km of the single Mercury Cell 

Chlor-Alkali facility associated with this 

rule. While there are three demographic 

groups (i.e., over age 25 without a high 

school diploma, those below the poverty 

level, and those aged 65 and up) around 

this facility that are higher than the 

national average, we find that no one is 

exposed to a cancer risk at or above 1- 

in-1 million or to a chronic noncancer 

TOSHI greater than 1. As such, the EPA 

determined that this action provides an 

ample margin of safety to protect public 

health for all populations, including 

communities already overburdened by 

pollution. Following is a more detailed 

description of how the agency considers 


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5See https://www.epa.gov/environmentaljustice. 

6When the demographic analysis was completed 

in mid-2020, there were 2 facilities in the mercury 

cell chlor-alkali source category and both were 

subject to 40 CFR part 63, subpart IIIII. However, 

in late 2020 one of those facilities converted to a 

non-mercury process. Therefore, currently only one 

facility remains in the source category. 

EJ in the context of regulatory 

development. 

Executive Order 12898 directs the 

EPA to identify the populations of 

concern who are most likely to 

experience unequal burdens from 

environmental harms; specifically, 

populations of people of color, lowincome populations, and indigenous 

peoples (59 FR 7629, February 16, 

1994). Additionally, Executive Order 

13985 is intended to advance racial 

equity and support underserved 

communities through federal 

government actions (86 FR 7009, 

January 20, 2021). Executive Order 

14008 further declares a policy ‘‘to 

secure environmental justice and spur 

economic opportunity for disadvantaged 

communities that have been historically 

marginalized overburdened by pollution 

and under-investment in housing, 

transportation, water and wastewater 

infrastructure, and health care’’ (86 FR 

7619, February 1, 2021). The EPA 

defines EJ as ‘‘the fair treatment and 

meaningful involvement of all people 

regardless of race, color, national origin, 

or income with respect to the 

development, implementation, and 

enforcement of environmental laws, 

regulations, and policies 5’’. The EPA 

further defines the term fair treatment to 

mean that ‘‘no group of people should 

bear a disproportionate burden of 

environmental harms and risks, 

including those resulting from the 

negative environmental consequences of 

industrial, governmental, and 

commercial operations or programs and 

policies’’. In recognizing that people of 

color and low-income populations often 

bear an unequal burden of 

environmental harms and risks, the EPA 

continues to consider ways of protecting 

them from adverse public health and 

environmental effects of air pollution. 

To examine the potential for any 

environmental justice issues that might 

be associated with the source category, 

we performed a demographic analysis, 

which is an assessment of risks to 

individual demographic groups of the 

populations living within 5 kilometers 

(km) and within 50 km of the facilities. 

In the analysis, we evaluated the 

distribution of HAP-related cancer and 

noncancer risks from the Mercury Cell 

Chlor-Alkali Plants source category 

across different demographic groups 

within the populations living near 

facilities. 

As mentioned above, the results of the 

demographic analysis for the source 

category indicate that three 

demographic groups included in the 

analysis are higher than the national 

average in percentage terms within 5 km 

of the facility.6 These groups include 

those over 25 without a high school 

diploma (17 percent versus 14 percent 

nationally), those below the poverty 

level (25 percent versus 14 percent 

nationally) and those aged 65 and up 

(18 percent versus 14 percent 

nationally). When examining the risk 

levels of those exposed to emissions 

from Mercury Cell Chlor-Alkali plants, 

we determined that no one is exposed 

to a cancer risk at or above 1-in-1 

million or to a chronic noncancer 

TOSHI greater than 1. The methodology 

and the results of the demographic 

analysis are presented in a technical 

report, Risk and Technology Review— 

Analysis of Demographic Factors for 

Populations Living Near Mercury Cell 

Chlor-Alkali Plants Source Category 

Operations, which is available in the 

docket. 

G. What analysis of children’s 

environmental health did we conduct? 

The EPA does not believe the 

environmental health or safety risks 

addressed by this action present a 

disproportionate risk to children. The 

health risk assessments for this action 

are contained in the document titled 

Residual Risk Assessment for the 

Mercury Cell Chlor-Alkali Plants Source 

Category in Support of the 2021 Risk 

and Technology Review Final Rule, 

available in the docket (Docket ID No. 

EPA–HQ–OAR–2020–0560). 

VI. Statutory and Executive Order 

Reviews 

Additional information about these 

statutes and Executive Orders can be 

found at: https://www.epa.gov/lawsregulations/laws-and-executive-orders. 

A. Executive Orders 12866: Regulatory 

Planning and Review and Executive 

Order 13563: Improving Regulation and 

Regulatory Review 

This action is a significant regulatory 

action that was submitted to the Office 

of Management and Budget (OMB) for 

review because it raises novel legal or 

policy issues. Any changes made in 

response to OMB recommendations 

have been documented in the docket. 

B. Paperwork Reduction Act (PRA) 

The information collection activities 

in rule have been submitted for 

approval to OMB under the PRA. The 

Information Collection Request (ICR) 

document that the EPA prepared has 

been assigned EPA ICR number 2046.11. 

You can find a copy of the ICR in the 

docket for this rule, and it is briefly 

summarized here. The information 

collection requirements are not 

enforceable until OMB approves them. 

The information requirements in this 

rulemaking are based on the 

notification, recordkeeping, and 

reporting requirements in the NESHAP 

General Provisions (40 CFR part 63, 

subpart A), which are mandatory for all 

operators subject to national emission 

standards. These notifications, reports, 

and records are essential in determining 

compliance, and are specifically 

authorized by CAA section 114 (42 

U.S.C. 7414). All information submitted 

to the EPA pursuant to the 

recordkeeping and reporting 

requirements for which a claim of 

confidentiality is made is safeguarded 

according to Agency policies set forth in 

40 CFR part 2, subpart B. 

The EPA is finalizing amendments to 

eliminate the SSM plan and reporting 

requirements; add requirements for 

electronic reporting of notifications and 

reports and performance test results; 

and add a reporting requirement for 

meeting the mercury emissions 

prohibitions. This information will be 

collected to assure compliance with the 

Mercury Cell Chlor-Alkali Plants 

NESHAP. 

Respondents/affected entities: The 

respondents to the recordkeeping and 

reporting requirements are owners or 

operators of flexible polyurethane foam 

fabrication operations subject to 40 CFR 

part 63, subpart IIIII. 

Respondent’s obligation to respond: 

Mandatory (40 CFR part 63, subpart 

IIIII). 

Estimated number of respondents: 1 

facility. 

Frequency of response: Initially, 

occasionally, and semi-annually. 

Total estimated burden: 3,567 total 

hours (per year). Burden is defined at 5 

CFR 1320.3(b). 

Total estimated cost: $457,200 (per 

year), includes $29,200 annualized 

capital or operation & maintenance 

costs. 

An agency may not conduct or 

sponsor, and a person is not required to 

respond to, a collection of information 

unless it displays a currently valid OMB 

control number. The OMB control 

numbers for the EPA’s regulations in 40 

CFR are listed in 40 CFR part 9. When 

OMB approves this ICR, the Agency will 

announce that approval in the Federal 

Register and publish a technical 

amendment to 40 CFR part 9 to display 

the OMB control number for the 


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approved information collection 

activities contained in this final rule. 

C. Regulatory Flexibility Act (RFA) 

I certify that this action will not have 

a significant economic impact on a 

substantial number of small entities 

under the RFA. This action will not 

impose any requirements on small 

entities. The ultimate parent company 

for the single affected facility in the 

source category is not a small entity 

given the Small Business 

Administration small business size 

definition for this industry (1,000 

employees or greater for NAICS 

325180). 

D. Unfunded Mandates Reform Act 

(UMRA) 

This action does not contain an 

unfunded mandate of $100 million or 

more as described in UMRA, 2 U.S.C. 

1531–1538, and does not significantly or 

uniquely affect small governments. 

While this action creates an enforceable 

duty on the private sector, the cost does 

not exceed $100 million or more in any 

one year. 

E. Executive Order 13132: Federalism 

This action does not have federalism 

implications. It will not have substantial 

direct effects on the states, on the 

relationship between the national 

government and the states, or on the 

distribution of power and 

responsibilities among the various 

levels of government. 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

This action does not have tribal 

implications as specified in Executive 

Order 13175. The mercury cell chloralkali plant affected by this final action 

is not owned or operated by tribal 

governments or located within tribal 

lands. Thus, Executive Order 13175 

does not apply to this action. 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

This action is not subject to Executive 

Order 13045 because it is not 

economically significant as defined in 

Executive Order 12866, and because the 

EPA does not believe the environmental 

health or safety risks addressed by this 

action present a disproportionate risk to 

children. This action’s health and risk 

assessments are contained in section 

IV.A of this preamble and the 

document, Residual Risk Assessment for 

the Mercury Cell Chlor-Alkali Plants 

Source Category in Support of the 2021 

Risk and Technology Review Final Rule, 

which is available in the docket for this 

rulemaking. 

H. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use 

This action is not a ‘‘significant 

energy action’’ because it is not likely to 

have a significant adverse effect on the 

supply, distribution, or use of energy. 

New standards are proposed for 40 CFR 

part 63, subpart IIIII to limit mercury 

and Cl emissions from mercury cell 

chlor-alkali plants. The proposed limits 

will have lower electricity costs for the 

one affected facility so it will not have 

a significant adverse effect on the 

supply, distribution, or use of energy. 

I. National Technology Transfer and 

Advancement Act (NTTAA) 

This rulemaking does not involve 

technical standards. 

J. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations 

The EPA believes that this action does 

not have disproportionately high and 

adverse human health or environmental 

effects on minority populations, lowincome populations, and/or indigenous 

peoples, as specified in Executive Order 

12898 (59 FR 7629, February 16, 1994). 

The documentation for this decision 

is contained in the technical report 

titled, Risk and Technology Review— 

Analysis of Demographic Factors for 

Populations Living Near Mercury Cell 

Chlor-Alkali Plants Source Category 

Operations, available in the docket for 

this action. 

K. Congressional Review Act (CRA) 

This action is subject to the CRA, and 

the EPA will submit a rule report to 

each House of the Congress and to the 

Comptroller General of the United 

States. This action is not a ‘‘major rule’’ 

as defined by 5 U.S.C. 804(2). 

List of Subjects in 40 CFR Part 63 

Environmental protection, 

Administrative practice and procedures, 

Air pollution control, Hazardous 

substances, Intergovernmental relations, 

Reporting and recordkeeping 

requirements. 

Michael S. Regan, 

Administrator. 

For the reasons set out in the 

preamble, 40 CFR part 63 is amended as 

follows: 

PART 63—NATIONAL EMISSION 

STANDARDS FOR HAZARDOUS AIR 

POLLUTANTS FOR SOURCE 

CATEGORIES 

■ 1. The authority citation for part 63 

continues to read as follows: 

Authority: 42 U.S.C. 7401 et seq. 

■ 2. The heading for subpart IIIII is 

revised to read as follows: 

Subpart IIIII—National Emission 

Standards for Hazardous Air Pollutants 

for Mercury Cell Chlor-Alkali Plants 

■ 3. Section 63.8180 is revised to read 

as follows: 

§ 63.8180 What is the purpose of this 

subpart? 

This subpart establishes national 

emission standards for hazardous air 

pollutants (NESHAP) for affected 

sources at mercury cell chlor-alkali 

plants. This subpart also establishes 

requirements to demonstrate initial and 

continuous compliance with all 

applicable emission limitations and 

work practice standards in this subpart. 

■ 4. Section 63.8182 is amended by 

revising paragraph (c) introductory text 

to read as follows: 

§ 63.8182 Am I subject to this subpart? 

* * * * * 

(c) Beginning on December 19, 2006, 

the provisions of subpart E of 40 CFR 

part 61 that apply to mercury cell chloralkali plants, which are listed in 

paragraphs (c)(1) through (3) of this 

section, are no longer applicable. 

* * * * * 

■ 5. Section 63.8184 is amended by 

revising paragraphs (a)(1) and (2) to read 

as follows: 

§ 63.8184 What parts of my plant does this 

subpart cover? 

(a) * * * 

(1) The mercury cell chlor-alkali 

production facility designates an 

affected source consisting of all cell 

rooms and ancillary operations used in 

the manufacture of product chlorine, 

product caustic, and by-product 

hydrogen at a plant site. This subpart 

covers mercury emissions from byproduct hydrogen streams and end box 

ventilation system vents, mercury 

fugitive emissions associated with cell 

rooms, hydrogen systems, caustic 

systems, and storage areas for mercurycontaining wastes; and chlorine fugitive 

emissions associated with the mercury 

cell chlor-alkali production facility. 

(2) The mercury recovery facility 

designates an affected source consisting 

of all processes and associated 

operations needed for mercury recovery 


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from wastes at a plant site. This subpart 

covers mercury emissions from mercury 

thermal recovery unit vents and fugitive 

emission sources of mercury associated 

with storage areas for mercurycontaining wastes. 

* * * * * 

■ 6. Section 63.8186 is amended by 

revising paragraph (a) to read as follows: 

§ 63.8186 When do I have to comply with 

this subpart? 

(a) If you have an existing affected 

source, you must comply according to 

the dates specified in paragraphs (a)(1) 

through (5) of this section, as applicable. 

(1) You must comply with each 

emission limitation, each work practice 

standard specified in paragraphs 

§ 63.8192(a) through (f) or each work 

practice standard in paragraphs 

§ 63.8192(e) through (g), and with each 

recordkeeping and reporting 

requirement in this subpart that applies 

to you by December 19, 2006, except as 

specified in paragraphs (a)(2) through 

(5) of this section. 

(2) You must comply with each work 

practice standard in § 63.8192(a) 

through (c) and (e) through (h) and the 

electronic reporting requirements in 

§ 63.8232(g), § 63.8252(g), and 

§ 63.8254(e) by November 7, 2022. 

(3) Until November 7, 2022, you must 

comply with the requirements in 

§ 63.8226(a) and the requirements 

specified in the startup, shutdown, and 

malfunction plan required at 

§ 63.8226(b). 

(4) On and after November 7, 2022, 

you must comply with the applicable 

requirements in paragraph § 63.8226(c). 

(5) On and after May 6, 2025, you 

must comply with the emission 

limitations in § 63.8190(a)(2)(ii) and the 

notification requirement in § 63.8252(h). 

* * * * * 

■ 7. Section 63.8190 is amended by 

revising paragraph (a)(2) to read as 

follows: 

§ 63.8190 What emission limitations must I 

meet? 

(a) * * * 

(2) Existing mercury cell chlor-alkali 

production facility. Until the 

compliance date listed in 

§ 63.8186(a)(5), you must comply with 

paragraph (a)(2)(i) of this section. On 

and after the compliance date listed in 

§ 63.8186(a)(5), you must comply with 

paragraph (a)(2)(ii) of this section. 

(i) During any consecutive 52-week 

period, you must not discharge to the 

atmosphere total mercury emissions in 

excess of the applicable limit in 

paragraph (a)(2)(i)(A) or (B) of this 

section calculated using the procedures 

in § 63.8243(a). 

(A) 0.076 grams of mercury per 

megagram of chlorine produced (1.5 × 

10¥4 pounds of mercury per ton of 

chlorine produced) from all by-product 

hydrogen streams and all end box 

ventilation system vents when both 

types of emission points are present. 

(B) 0.033 grams of mercury per 

megagram of chlorine produced (6.59 × 

10¥5 pounds of mercury per ton of 

chlorine produced) from all by-product 

hydrogen streams when end box 

ventilation systems are not present. 

(ii) Emissions of mercury are 

prohibited from an existing mercury cell 

chlor-alkali production facility. 

* * * * * 

■ 8. Section 63.8192 is amended by 

revising the introductory text, paragraph 

(a), and paragraph (g) introductory text, 

and adding paragraph (h) to read as 

follows: 

§ 63.8192 What work practice standards 

must I meet? 

In accordance with the compliance 

dates specified in § 63.8186(a)(1), you 

must meet the work practice 

requirements specified in paragraphs (a) 

through (f) of this section. As an 

alternative to the requirements specified 

in paragraphs (a) through (d) of this 

section, you may choose to comply with 

paragraph (g) of this section. On and 

after the compliance date specified in 

§ 63.8186(a)(2) and until the compliance 

date specified in § 63.8186(a)(5), you 

must meet the work practice 

requirements specified in paragraphs (a) 

through (c) and (e) through (h) of this 

section. 

(a) You must meet the work practice 

standards in Tables 1 through 4 to this 

subpart. 

* * * * * 

(g) You must institute a cell room 

monitoring program to continuously 

monitor the mercury vapor 

concentration in the upper portion of 

each cell room and to take corrective 

actions as quickly as possible when 

elevated mercury vapor levels are 

detected. As specified in 

§ 63.8252(e)(1)(iv), you must prepare 

and submit to the Administrator, a cell 

room monitoring plan containing the 

elements listed in Table 5 to this 

subpart and meet the requirements in 

paragraphs (g)(1) through (4) of this 

section. 

* * * * * 

(h) You must comply with the 

requirements specified in paragraphs 

(h)(1) through (4) of this section to 

reduce fugitive chlorine emissions in 

the mercury cell chlor-alkali production 

facility affected source. 

(1) You must identify each piece of 

equipment located throughout the 

mercury cell chlor-alkali production 

facility affected source that contains 

chlorine gas at a concentration of at 

least 5 percent by volume. You may 

identify equipment by a list or on a 

process or piping diagram. You may 

exclude equipment that is under 

negative pressure. 

(2) You must install ambient chlorine 

sensors at the mercury cell chlor-alkali 

production facility affected source to 

measure the ambient chlorine 

concentration. 

(i) Ambient chlorine sensors must 

have a detection limit of 0.5 ppmv or 

less. 

(ii) The sensors must be operated 

continuously to obtain a measurement 

at least once each 15 minutes. 

(iii) You must identify the location of 

the sensors by a list or on a process or 

piping diagram. 

(iv) You must operate, calibrate, and 

maintain these sensors in accordance 

with manufacturer instructions. 

(v) You must keep the necessary parts 

for routine repairs of the sensors readily 

available. 

(3) You must perform inspections to 

identify leaks of chlorine using olfactory 

observations according to the schedules 

in paragraphs (h)(3)(i) and (ii) of this 

section. A leak is detected when there 

is an olfactory observation of a leak. If 

a leak is detected, you must comply 

with the repair provisions in paragraph 

(h)(4) of this section. 

(i) At least once each 12 hours, you 

must inspect each piece of equipment 

located throughout the mercury cell 

chlor-alkali production facility affected 

source that contains chlorine gas at a 

concentration of greater than 5 percent 

by volume for chlorine leaks, excluding 

equipment that is under negative 

pressure. 

(ii) Within 1 hour of detection of a 1- 

hour average chlorine concentration of 2 

ppmv or greater by a sensor installed 

and operated in accordance with 

paragraph (h)(2) of this section, you 

must inspect each piece of equipment 

located throughout the mercury cell 

chlor-alkali production facility affected 

source that contains chlorine gas at a 

concentration of greater than 5 percent 

by volume for chlorine leaks, excluding 

equipment that is under negative 

pressure. 

(4) You must undertake a first attempt 

at repair no later than 1 hour after the 

leak is detected, and the leak must be 

repaired no later than 72 hours after the 

leak is detected. A leak is repaired when 

there is no olfactory observation of a 

leak. 


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■ 9. Section 63.8222 is revised to read 

as follows: 

§ 63.8222 What are my operation and 

maintenance requirements? 

At all times you must operate and 

maintain any affected source, including 

associated air pollution control 

equipment and monitoring equipment, 

in a manner consistent with safety and 

good air pollution control practices for 

minimizing emissions. The general duty 

to minimize emissions does not require 

you to make any further efforts to 

reduce emissions if levels required by 

the applicable standards have been 

achieved. Determination of whether a 

source is operating in compliance with 

operation and maintenance 

requirements will be based on 

information available to the 

Administrator which may include, but 

is not limited to, monitoring results, 

review of operation and maintenance 

procedures, review of operation and 

maintenance records, reports and 

inspection of the source. 

■ 10. Section 63.8226 is revised to read 

as follows: 

§ 63.8226 What are my general 

requirements for complying with this 

subpart? 

(a) Until November 7, 2022, you must 

be in compliance with the applicable 

emission limitations in § 63.8190 and 

the applicable work practice standards 

in § 63.8192 at all times, except during 

periods of startup, shutdown, and 

malfunction. 

(b) Until November 7, 2022, you must 

develop and operate as specified by a 

written startup, shutdown, and 

malfunction plan (SSMP) according to 

the provisions in § 63.6(e)(3). 

(c) On and after November 7, 2022, 

the provisions of paragraphs (a) and (b) 

of this section no longer apply, and you 

must be in compliance with the 

applicable emission limitations in 

§ 63.8190 and the applicable work 

practice standards in § 63.8192 at all 

times. 

■ 11. Section 63.8232 is amended by 

revising the introductory text and 

paragraph (a) and adding paragraph (g) 

to read as follows: 

§ 63.8232 What test methods and other 

procedures must I use to demonstrate 

initial compliance with the emission limits? 

You must conduct a performance test 

for each by-product hydrogen stream, 

end box ventilation system vent, and 

mercury thermal recovery unit vent 

according to the conditions detailed in 

paragraphs (a) through (d) of this 

section. 

(a) You must conduct each 

performance test under conditions 

representative of normal operations. 

You may not conduct performance tests 

during periods of startup, shutdown, or 

malfunction. You must record the 

process information that is necessary to 

document operating conditions during 

the test and include in such record an 

explanation to support that such 

conditions represent normal operation. 

Upon request, you shall make available 

to the Administrator such records as 

may be necessary to determine the 

conditions of performance tests. 

* * * * * 

(g) Within 60 days after the date of 

completing each performance test 

specified in this section, you must 

submit the results of the performance 

test following the procedures specified 

in paragraphs (g)(1) through (3) of this 

section. 

(1) Data collected using test methods 

supported by the EPA’s Electronic 

Reporting Tool (ERT) as listed on the 

EPA’s ERT website (https://

www.epa.gov/electronic-reporting-airemissions/electronic-reporting-tool-ert) 

at the time of the test. Submit the results 

of the performance test to the EPA via 

the Compliance and Emissions Data 

Reporting Interface (CEDRI), which can 

be accessed through the EPA’s Central 

Data Exchange (CDX) (https://

cdx.epa.gov/). The data must be 

submitted in a file format generated 

using the EPA’s ERT. Alternatively, you 

may submit an electronic file consistent 

with the extensible markup language 

(XML) schema listed on the EPA’s ERT 

website. 

(2) Data collected using test methods 

that are not supported by the EPA’s ERT 

as listed on the EPA’s ERT website at 

the time of the test. The results of the 

performance test must be included as an 

attachment in the ERT or an alternate 

electronic file consistent with the XML 

schema listed on the EPA’s ERT 

website. Submit the ERT generated 

package or alternative file to the EPA via 

CEDRI. 

(3) Confidential business information 

(CBI). Do not use CEDRI to submit 

information you claim as CBI. Anything 

submitted using CEDRI cannot later be 

claimed CBI. Although we do not expect 

persons to assert a claim of CBI, if you 

wish to assert a CBI claim for some of 

the information submitted under 

paragraph (g)(1) or (2) of this section, 

you must submit a complete file, 

including information claimed to be 

CBI, to the EPA. The file must be 

generated using the EPA’s ERT or an 

alternate electronic file consistent with 

the XML schema listed on the EPA’s 

ERT website. Submit the file on a 

compact disc, flash drive, or other 

commonly used electronic storage 

medium and clearly mark the medium 

as CBI. Mail the electronic medium to 

U.S. EPA/OAQPS/CORE CBI Office, 

Attention: Group Leader, Measurement 

Policy Group, MD C404–02, 4930 Old 

Page Rd., Durham, NC 27703. The same 

file with the CBI omitted must be 

submitted to the EPA via the EPA’s CDX 

as described in paragraphs (g)(1) and (2) 

of this section. All CBI claims must be 

asserted at the time of submission. 

Furthermore, under CAA section 114(c), 

emissions data is not entitled to 

confidential treatment, and the EPA is 

required to make emissions data 

available to the public. Thus, emissions 

data will not be protected as CBI and 

will be made publicly available. 

■ 12. Section 63.8236 is amended by 

revising paragraph (c) introductory text 

and adding paragraphs (e) and (f) to read 

as follows: 

§ 63.8236 How do I demonstrate initial 

compliance with the emission limitations 

and work practice standards? 

* * * * * 

(c) Prior to the compliance date 

specified in § 63.8186(a)(2), for each 

affected source, you have demonstrated 

initial compliance with the applicable 

work practice standards in § 63.8192 if 

you comply with paragraphs (c)(1) 

through (7) of this section. 

* * * * * 

(e) On and after the compliance date 

specified in § 63.8186(a)(2), for each 

affected source, you have demonstrated 

initial compliance with the applicable 

work practice standards for mercury 

emissions in § 63.8192(a) through (c) 

and (e) through (g) if you comply with 

paragraphs (e)(1) through (4) of this 

section. 

(1) You have submitted a Revised 

Notification of Compliance Status 

containing the results of the initial 

compliance demonstration according to 

the requirements in § 63.8252(f). 

(2) You certify in your Revised 

Notification of Compliance Status that 

you are operating according to the work 

practice standards for mercury 

emissions in § 63.8192(a) through (c), 

(e), and (f). 

(3) You have submitted your cell 

room monitoring plan as part of your 

Revised Work Practice Notification of 

Compliance Status and you certify in 

your Revised Notification of 

Compliance Status that you are 

operating according to the continuous 

cell room monitoring program under 

§ 63.8192(g). 

(4) You have re-submitted your 

washdown plan as part of your Revised 

Notification of Compliance Status and 

you re-certify in your Revised 


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Notification of Compliance Status that 

you are operating according to your 

washdown plan under § 63.8192(e). 

(f) On and after the compliance date 

specified in § 63.8186(a)(2), for each 

affected source, you have demonstrated 

initial compliance with the applicable 

work practice standards for chlorine 

emissions in § 63.8192(h) if you meet 

the requirements of paragraphs (f)(1) 

through (3) of this section. 

(1) You have installed chlorine 

sensors in accordance with 

§ 63.8192(h)(2). 

(2) You have certified in your Revised 

Notification of Compliance Status that 

you are operating according to the work 

practice standards in § 63.8192(h). 

(3) You have submitted your Revised 

Notification of Compliance Status 

containing the results of the initial 

compliance demonstration according to 

the requirements in § 63.8252(f). 

■ 13. Section 63.8242 is amended by 

revising the section heading and 

paragraphs (a)(2) and (a)(3)(v) to read as 

follows: 

§ 63.8242 What are the installation, 

operation, and maintenance requirements 

for my continuous mercury monitoring 

systems? 

(a) * * * 

(2) Each mercury continuous 

emissions monitor analyzer must have a 

detector with the capability to detect a 

mercury concentration of either 0.1 mg/ 

m3 or 0.5 times the mercury 

concentration level measured during the 

performance test conducted according 

to § 63.8232. 

(3) * * * 

(v) Ongoing data quality assurance 

procedures according to the 

requirements of § 63.8(d)(1) and (2). You 

shall keep these written procedures on 

record for the life of the affected source 

or until the affected source is no longer 

subject to the provisions of this part, to 

be made available for inspection, upon 

request, by the Administrator. If the 

performance evaluation plan is revised, 

you shall keep previous (i.e., 

superseded) versions of the performance 

evaluation plan on record to be made 

available for inspection, upon request, 

by the Administrator, for a period of 5 

years after each revision to the plan. The 

program of corrective action shall be 

included in the plan required under 

§ 63.8(d)(2). 

* * * * * 

■ 14. Section 63.8246 is amended by 

revising paragraphs (b)(1) introductory 

text and (c) and adding paragraph (d) to 

read as follows: 

§ 63.8246 How do I demonstrate 

continuous compliance with the emission 

limitations and work practice standards? 

* * * * * 

(b) * * * 

(1) For each mercury thermal recovery 

unit vent, you must demonstrate 

continuous compliance with the 

applicable emission limit specified in 

§ 63.8190(a)(3) by maintaining the outlet 

mercury daily-average concentration no 

higher than the applicable limit. To 

determine the outlet mercury 

concentration, you must monitor 

according to paragraph (b)(1)(i) or (ii) of 

this section. 

* * * * * 

(c) You must demonstrate continuous 

compliance with the applicable work 

practice standards for mercury 

emissions in § 63.8192 by maintaining 

records in accordance with § 63.8256(c) 

and (e). 

(d) You must demonstrate continuous 

compliance with the applicable work 

practice standards for chlorine 

emissions in § 63.8192(h) by 

continuously operating the chlorine 

sensors required by § 63.8192(h)(2), 

inspecting equipment in accordance 

with § 63.8192(h)(3), repairing 

equipment in accordance with 

§ 63.8192(h)(4) and maintaining records 

in accordance with § 63.8256(f). 

■ 15. Section 63.8248 is amended by 

revising paragraphs (a) introductory 

text, (a)(1) and (2), and (2), and adding 

paragraph (b) introductory text to read 

as follows: 

§ 63.8248 What other requirements must I 

meet? 

(a) Deviations. The instances specified 

in paragraphs (a)(1) through (4) of this 

section are deviations and must be 

reported according to the requirements 

in § 63.8254 and recorded according to 

the requirements in § 63.8256(a)(2). 

(1) You must report each instance in 

which you did not meet each emission 

limitation in § 63.8190 that applies to 

you. 

(2) You must report each instance in 

which you did not meet each work 

practice standard in § 63.8192 that 

applies to you. 

* * * * * 

(b) * * * The provisions of 

paragraphs (b)(1) through (3) of this 

section apply until November 7, 2022. 

On and after November 7, 2022, the 

provisions of paragraphs (b)(1) through 

(3) of this section no longer apply. 

* * * * * 

■ 16. Section 63.8252 is amended by 

revising paragraphs (d) and (e)(1)(i) and 

adding paragraphs (f) through (h) to read 

as follows: 

§ 63.8252 What notifications must I submit 

and when? 

* * * * * 

(d) For each performance test that you 

are required to conduct for by-product 

hydrogen streams and end box 

ventilation system vents and for 

mercury thermal recovery unit vents, 

you must submit a notification of intent 

to conduct a performance test at least 60 

calendar days before the performance 

test is scheduled to begin as required in 

§ 63.7(b)(1). 

(e) * * * 

(1) * * * 

(i) If you choose not to implement a 

cell room monitoring program according 

to § 63.8192(g), a certification that you 

are operating according to the 

applicable work practice standards for 

mercury emissions in § 63.8192(a) 

through (d) and your floor-level mercury 

vapor measurement plan required by 

§ 63.8192(d). 

* * * * * 

(f) You must submit a Revised 

Notification of Compliance Status before 

the close of business on the date 30 days 

after the compliance date in 

§ 63.8186(a)(2) containing the items in 

paragraphs (f)(1) through (5) of this 

section: 

(1) A certification that you are 

operating according to the work practice 

standards for mercury emissions in 

§ 63.8192(a) through (c) and (e) through 

(g). 

(2) Your cell room monitoring plan, 

including your initial action level 

determined in accordance with 

§ 63.8192(g)(2), and a certification that 

you are operating according to the 

continuous cell room monitoring 

program under § 63.8192(g). 

(3) Your washdown plan, and a 

certification that you are operating 

according to your washdown plan under 

§ 63.8192(e). 

(4) Records of the mass of virgin 

mercury added to cells for every year 

since 2001. 

(5) A certification that you have 

installed chlorine sensors in accordance 

with § 63.8192(h)(2) and that you are 

operating according to the work practice 

standards for chlorine emissions in 

§ 63.8192(h). 

(g) You must submit all subsequent 

Notification of Compliance Status 

reports and Revised Notification of 

Compliance Status reports in PDF 

format to the EPA via CEDRI, which can 

be accessed through EPA’s CDX (https:// 

cdx.epa.gov/). 

(h) You must submit a notification of 

compliance with the prohibition of 

mercury emissions as specified in 

paragraphs (e)(1) and (2) of this section. 


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(1) The notification must include the 

information specified in paragraph 

(e)(1)(i) and (ii) of this section. 

(i) A certification that the requirement 

of § 63.8190(a)(2)(ii) has been met. 

(ii) A brief explanation of how the 

requirement of § 63.8190(a)(2)(ii) has 

been met. 

(2) You must submit this notification 

before the close of business on the 30th 

calendar day following the date when 

compliance with § 63.8190(a)(2)(ii) is 

attained. 

■ 17. Section 63.8254 is amended by: 

■ a. Revising paragraph (b) introductory 

text; 

■ b. Removing and reserving paragraph 

(b)(4); 

■ c. Revising paragraphs (b)(7) through 

(9); 

■ d. Adding paragraphs (b)(13) and (14); 

■ e. Removing and reserving paragraph 

(c); and 

■ f. Adding paragraph (e). 

The revisions and additions read as 

follows: 

§ 63.8254 What reports must I submit and 

when? 

* * * * * 

(b) Compliance report contents. Each 

compliance report must contain the 

information in paragraphs (b)(1) through 

(3) of this section, and as applicable, 

paragraphs (b)(5) through (13) of this 

section. 

* * * * * 

(7) For each deviation from the 

requirements for work practice 

standards in § 63.8192, the information 

in paragraphs (b)(7)(i) and (ii) of this 

section. 

(i) For each deviation from the 

mercury work practice standards in 

Tables 1 through 4 to this subpart that 

occurs at an affected source (including 

deviations where the response intervals 

were not adhered to as described in 

§ 63.8192(b)), each deviation from the 

cell room monitoring program 

monitoring and data recording 

requirements in § 63.8192(g)(3), and 

each deviation from the response 

intervals required by § 63.8192(g)(4) 

when an action level is exceeded, the 

compliance report must contain the 

information in paragraphs (b)(1) through 

(3) of this section and the information 

in paragraphs (b)(7)(i)(A) through (C) of 

this section. 

(A) The total operating time of each 

affected source during the reporting 

period. 

(B) Information on the number, date, 

time, duration, and cause of deviations 

(including unknown cause, if 

applicable), as applicable, and the 

corrective action taken. 

(C) A list of the affected sources or 

equipment. 

(ii) For each deviation from the 

fugitive chlorine requirements in 

§ 63.8192(h), including periods when 

the chlorine sensors required by 

§ 63.8192(h)(2) were not operating; 

instances where the chlorine sensors 

required by § 63.8192(h)(2) were not 

calibrated and maintained in 

accordance with manufacturer 

instructions or spare parts were not 

maintained; instances where 

inspections were not performed in 

accordance with § 63.8192(h)(3)(i) and 

(ii); and instances where leak repair 

intervals in § 63.8192(h)(4) were not 

met; the compliance report must contain 

the information in paragraphs (b)(1) 

through (3) of this section and the 

information in paragraphs (b)(7)(ii)(A) 

through (C) of this section. 

(A) The total operating time of each 

affected source during the reporting 

period. 

(B) Information on the number, date, 

time, duration, and cause of deviations 

(including unknown cause, if 

applicable), as applicable, and the 

corrective action taken. 

(C) A list of the affected sources or 

equipment. 

(8) For each deviation from an 

emission limitation occurring at an 

affected source where you are using a 

mercury continuous emission monitor, 

according to the site-specific monitoring 

plan required in § 63.8242(a)(3), to 

comply with the emission limitation in 

this subpart, you must include the 

information in paragraphs (b)(1) through 

(3) of this section and the information 

in paragraphs (b)(8)(i) through (xv) of 

this section. 

(i) A list of the affected sources and 

equipment. 

(ii) The date and time that each 

deviation started and stopped. 

(iii) For each deviation, the cause of 

the deviation (including unknown 

cause, if applicable), as applicable, and 

corrective action taken. 

(iv) For each deviation, an estimate of 

the quantity of each regulated pollutant 

emitted over any emission limit. 

(v) A description of the method used 

to estimate the emissions. 

(vi) The date and time of each 

instance in which a continuous 

monitoring system was inoperative, 

except for zero (low-level) and highlevel checks. 

(vii) The date, time, and duration of 

each instance in which a continuous 

monitoring system was out-of-control, 

including the information in 

§ 63.8(c)(8). 

(viii) A summary of the total duration 

of the deviation during the reporting 

period and the total duration as a 

percent of the total source operating 

time during that reporting period. 

(ix) A breakdown of the total duration 

of the deviations during the reporting 

period including those that are due to 

control equipment problems, process 

problems, other known causes, and 

other unknown causes. 

(x) A summary of the total duration of 

continuous monitoring system 

downtime during the reporting period 

and the total duration of monitoring 

system downtime as a percent of the 

total source operating time during the 

reporting period. 

(xi) An identification of each 

hazardous air pollutant that was 

monitored at the affected source. 

(xii) A brief description of the process 

units. 

(xiii) A brief description of the 

continuous monitoring system. 

(xiv) The date of the latest continuous 

monitoring system certification or audit. 

(xv) A description of any changes in 

monitoring system, processes, or 

controls since the last reporting period. 

(9) For each deviation from an 

operation and maintenance standard 

occurring at an affected source where 

you are using the periodic monitoring 

option specified in § 63.8240(b) and 

your final control device is not a 

nonregenerable carbon adsorber, the 

compliance report must include the 

information in paragraphs (b)(1) through 

(3) of this section and the information 

in paragraphs (b)(9)(i) through (xiii) of 

this section. 

(i) A list of the affected sources or 

equipment. 

(ii) The total operating time of each 

affected source during the reporting 

period. 

(iii) Information on the number, 

duration, and cause of deviations 

(including unknown cause, if 

applicable), as applicable, and the 

corrective action taken. 

(iv) For each deviation, an estimate of 

the quantity of each regulated pollutant 

emitted over any emission limit. 

(v) A description of the method used 

to estimate the emissions. 

(vi) The date and time of each 

instance in which a CPMS was 

inoperative, except for zero (low-level) 

and high-level checks. 

(vii) The date, time, and duration of 

each instance in which a CPMS was outof-control, including the information 

specified in § 63.8(c)(8). 

(viii) A summary of the total duration 

of the deviation during the reporting 

period and the total duration as a 

percent of the total source operating 

time during that reporting period. 

(ix) A breakdown of the total duration 

of the deviations during the reporting 


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period including those that are due to 

control equipment problems, process 

problems, other known causes, and 

other unknown causes. 

(x) A summary of the total duration of 

continuous monitoring system 

downtime during the reporting period 

and the total duration of monitoring 

system downtime as a percent of the 

total source operating time during the 

reporting period. 

(xi) A brief description of the CPMS. 

(xii) The date of the latest CPMS 

certification or audit. 

(xiii) A description of any changes in 

monitoring system, processes, or 

controls since the last reporting period. 

* * * * * 

(13) The compliance report must 

contain the information specified in 

paragraphs (b)(13)(i) through (iii) for 

each instance where the 1-hour average 

concentration of chlorine detected by a 

chlorine sensor required by 

§ 63.8192(h)(2) was 2 ppmv or greater. 

(i) The date and times a chlorine 

sensor detected chlorine concentrations 

of 2 ppmv or greater. 

(ii) The location of the sensor. 

(iii) The date and time that the sensor 

returned to a 1-hour average 

concentration of less than 2 ppmv. 

(14) The compliance report must 

contain the information specified in 

paragraphs (b)(14)(i) and (ii) for all 

inspections conducted under either 

§ 63.8192(h)(3)(i) or (ii). You must also 

record the information in paragraphs 

(b)(14)(iii) through (vii) of this section 

for each leak identified. 

(i) The date of each inspection. 

(ii) The reason for each inspection 

(i.e., a routine inspection conducted 

each 12 hours or an inspection 

conducted in response to a 2 ppmv or 

greater 1-hour average concentration of 

chlorine, as detected by a sensor). 

(iii) Location of the leak. 

(iv) Date and time the leak was 

identified. 

(v) Date and time of initial repair 

attempt. 

(vi) Date and time the leak is repaired. 

(vii) A description of the repair made 

to stop the leak. 

* * * * * 

(e) The owner or operator must 

submit semiannual compliance reports 

in PDF formatto the EPA viaCEDRI, 

which can be accessedthrough EPA’s 

CDX (https://cdx.epa.gov/). 

■ 18. Section 63.8256 is amended by 

revising paragraphs (a)(2) and (c) 

introductory text and adding paragraphs 

(e) and (f) to read as follows: 

§ 63.8256 What records must I keep? 

(a) * * * 

(2) The records specified in 

paragraphs (a)(2)(i) and (ii) of this 

section related to deviations. 

(i) Record actions taken to minimize 

emissions in accordance with § 63.8222 

and any corrective actions taken to 

return the affected unit to its normal or 

usual manner of operation. 

(ii) Records of the information 

reported as required in § 63.8254(b)(7) 

through (9) and (11) through (13). 

* * * * * 

(c) Records associated with the work 

practice standards for mercury 

emissions that must be kept prior to the 

compliance date in § 63.8186(a)(2). 

* * * * * 

(e) Records associated with the work 

practice standards for mercury 

emissions that must be kept after the 

compliance date in § 63.8186(a)(2). 

(1) The records specified in Table 9 to 

this subpart related to the work practice 

standards in Tables 1 through 4 of this 

subpart. 

(2) You must maintain a copy of your 

current washdown plan and records of 

when each washdown occurs. 

(3) You must maintain records of the 

mass of virgin mercury added to cells 

for each reporting period. 

(4) You must keep your current cell 

room monitoring plan and the records 

specified in paragraphs (e)(4)(i) through 

(v) of this section. 

(i) Records of the monitoring 

conducted in accordance with 

§ 63.8192(g)(2)(i) to establish your 

action level, and records demonstrating 

the development of this action level. 

(ii) Records of the cell room mercury 

concentration monitoring data collected. 

(iii) Instances when the action level is 

exceeded. 

(iv) Records specified in 

§ 63.8192(g)(4)(i) for maintenance 

activities that cause the mercury vapor 

concentration to exceed the action level. 

(v) Records of all inspections and 

corrective actions taken in response to 

a non-maintenance related situation in 

which the mercury vapor concentration 

exceeds the action level. 

(f) You must keep the records 

specified in paragraphs (f)(1) through (4) 

of this section associated with the work 

practice standards for fugitive chlorine 

emissions specified in § 63.8192(h) after 

the compliance date in § 63.8186(a)(2). 

(1) Identification of all equipment in 

the mercury cell chlor-alkali production 

facility affected source containing 

chlorine gas at a concentration of greater 

than 5 percent by volume. You may 

exclude equipment that is under 

negative pressure. 

(2) Records of the information 

reported as required in § 63.8254(b)(13) 

and (14). 

(3) You must record the information 

specified in paragraphs (f)(3)(i) through 

(iv) of this section for the chlorine 

sensors required by § 63.8192(h)(2). 

(i) The location, manufacturer, and 

model number of each sensor. 

(ii) The manufacturer’s instructions 

for operation, maintenance, and 

calibration of the chlorine sensors. 

(iii) Records of all maintenance and 

calibration of the chlorine sensors. 

(iv) You must record all periods when 

the chlorine sensors are not operating. 

(4) You must maintain records of all 

chlorine concentration measurements. 

■ 19. Section 63.8262 is revised to read 

as follows: 

§ 63.8262 What parts of the General 

Provisions apply to me? 

Table 10 to this subpart shows which 

parts of the General Provisions in 

§§ 63.1 through 63.13 apply to you. 

■ 20. Section 63.8264 is amended by 

revising paragraph (c) introductory text 

and adding paragraph (c)(5) to read as 

follows: 

§ 63.8264 Who implements and enforces 

this subpart? 

* * * * * 

(c) The authorities in paragraphs (c)(1) 

through (5) of this section will not be 

delegated to State, local, or tribal 

agencies. 

* * * * * 

(5) Approval of an alternative to any 

electronic reporting to the EPA required 

by this subpart. 

■ 21. Section 63.8266 is amended by 

revising the definition of ‘‘Deviation’’ to 

read as follows: 

§ 63.8266 What definitions apply to this 

subpart? 

* * * * * 

Deviation means any instance in 

which an affected source subject to this 

subpart, or an owner or operator of such 

a source: 

(1) Fails to meet any requirement or 

obligation established by this subpart 

including, but not limited to, any 

emission limitation (including any 

operating limit) or work practice 

standard (including any monitoring 

plan); 

(2) Fails to meet any term or condition 

that is adopted to implement an 

applicable requirement in this subpart 

and that is included in the title V 

operating permit for any affected source 

required to obtain such a permit; or 

(3) Fails to take corrective actions 

within 48 hours that result in parameter 

monitoring values being within range. 

* * * * * 


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■ 22. Table 5 to subpart IIIII of part 63 

is amended by revising the introductory 

text to read as follows: 

Table 5 to Subpart IIIII of Part 63— 

Required Elements of Floor-Level 

Mercury Vapor Measurement and Cell 

Room Monitoring Plans 

Your Floor-Level Mercury Vapor 

Measurement Plan required by 

§ 63.8192(d) prior to the applicable 

compliance date specified in 

§ 63.8186(a)(2) and Cell Room 

Monitoring Plan required by 

§ 63.8192(g) must contain the elements 

listed in the following table: 

* * * * * 

■ 23. Table 10 to subpart IIIII of part 63 

is revised to read as follows: 

Table 10 to Subpart IIIII of Part 63— 

Applicability of General Provisions to 

Subpart IIIII 

As stated in § 63.8262, you must 

comply with the applicable General 

Provisions requirements according to 

the following table: 

Citation Subject Applies to 

subpart IIIII Explanation 

§ 63.1 .............................................................. Applicability .................................................. Yes.

§ 63.2 .............................................................. Definitions .................................................... Yes.

§ 63.3 .............................................................. Units and Abbreviations .............................. Yes.

§ 63.4 .............................................................. Prohibited Activities ..................................... Yes.

§ 63.5 .............................................................. Construction/Reconstruction ........................ Yes.

§ 63.6(a)–(g), (i), (j), except for (e)(1)(i) and 

(ii), (e)(3), and (f)(1).

Compliance with Standards and Maintenance Requirements.Yes.

§ 63.6(e)(1)(i) and (ii), (e)(3), and (f)(1) ......... SSM Requirements ..................................... Yes ............ Only applies until the date specified in § 63.8186(a)(3). 

§ 63.6(h) ......................................................... Compliance with Opacity and Visible Emission Standards.No ............. Subpart IIIII does not have opacity and visible emission 

standards. 

§ 63.7(a)–(h), except for (a)(2) and (e)(1) ..... Performance Testing Requirements ............ Yes ............ Subpart IIIII specifies additional requirements related to 

site-specific test plans and the conduct of performance 

tests. 

§ 63.7(a)(2) ..................................................... Applicability and Performance Test Dates .. No ............. Subpart IIIII requires the performance test to be performed on the compliance date. 

§ 63.7(e)(1) ..................................................... Performance Test Conditions ...................... No ............. See § 63.8232(a). 

§ 63.8(a)(1), (a)(3); (b); (c)(1)(ii), (2)–(4), (6)– 

(8); (d)(1)–(2); (e); and (f)(1)–(5).

Monitoring Requirements ............................ Yes ............ Only applies for CEMS, except Subpart IIIII specifies how 

and when the performance evaluation results are reported. 

§ 63.8(a)(2) ..................................................... Continuous Monitoring System (CMS) Requirements.No ............. Subpart IIIII requires a site-specific monitoring plan in lieu 

of a promulgated performance specification for a mercury concentration CMS. 

§ 63.8(a)(4) ..................................................... Additional Monitoring Requirements for 

Control Devices in § 63.11.

No ............. Subpart IIIII does not require flares. 

§ 63.8(c)(1)(i) and (iii) ..................................... CMS Operation and SSM Plan ................... Yes ............ Only applies until the date specified in § 63.8186(a)(3). 

§ 63.8(c)(5) ..................................................... COMS Minimum Procedures ....................... No ............. Subpart IIIII does not have opacity and visible emission 

standards. 

§ 63.8(d)(3) ..................................................... Written Procedures for CMS ....................... No ............. See § 63.8242(a)(3)(v). 

§ 63.8(f)(6) ...................................................... Alternative to Relative Accuracy Test ......... No ............. Subpart IIIII does not require CEMS. 

§ 63.8(g) ......................................................... Data Reduction ............................................ No ............. Subpart IIIII specifies mercury concentration CMS data 

reduction requirements. 

§ 63.9(a)–(e), (g)–(j) ....................................... Notification Requirements ........................... Yes.

§ 63.9(f) .......................................................... Notification of VE/Opacity Test ................... No ............. Subpart IIIII does not have opacity and visible emission 

standards. 

§ 63.9(k) ......................................................... Electronic reporting procedures .................. Yes ............ Only as specified in § 63.9(j). 

§ 63.10(a); (b)(1); (b)(2)(vi)–(xii), (xiv); (b)(3); 

(c)(1)–(14); (d)(1), (4); (e); (f).

Recordkeeping/Reporting ............................ Yes.

§ 63.10(b)(2)(i)–(v) ......................................... Recordkeeping/Reporting Associated with 

Startup, Shutdown, and Malfunctions.

Yes ............ Only applies until the date specified in § 63.8186(a)(3). 

§ 63.10(b)(2)(xiii) ............................................ CMS Records for RATA Alternative ............ No ............. Subpart IIIII does not require CEMS. 

§ 63.10(c)(15) ................................................. Use of SSM Plan ......................................... Yes ............ Only applies until the date specified in § 63.8186(a)(3). 

§ 63.10(d)(2) ................................................... Performance Test Results ........................... No ............. This subpart at 63.8232(g) specifies how and when the 

performance test results are reported electronically. 

§ 63.10(d)(3) ................................................... Reporting Opacity or VE Observations ....... No ............. Subpart IIIII does not have opacity and visible emission 

standards. 

§ 63.10(d)(5) ................................................... Startup, Shutdown, and Malfunction Reports.No.

§ 63.10(e)(2)(i) ................................................ CEM Reporting ............................................ Yes ............ Except this subpart specifies how and when the performance evaluation results are reported. 

§ 63.11 ............................................................ Flares ........................................................... No ............. Subpart IIIII does not require flares. 

§ 63.12 ............................................................ Delegation ................................................... Yes.

§ 63.13 ............................................................ Addresses .................................................... Yes.

§ 63.14 ............................................................ Incorporation by Reference ......................... Yes.

§ 63.15 ............................................................ Availability of Information ............................ Yes.

[FR Doc. 2022–09658 Filed 5–5–22; 8:45 am] 

BILLING CODE 6560–50–P 


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