[Federal Register Volume 85, Number 129 (Monday, July 6, 2020)]
[Rules and Regulations]
[Pages 40386-40440]
[FR Doc No: 2020-05898]

Vol. 85

Monday,

No. 129

July 6, 2020

Part II

 Environmental Protection Agency

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40 CFR Part 63

National Emission Standards for Hazardous Air Pollutants: Generic
Maximum Achievable Control Technology Standards Residual Risk and
Technology Review for Ethylene Production; Final Rule

Federal Register / Vol. 85, No. 129 / Monday, July 6, 2020 / Rules
and Regulations

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2017-0357; FRL-10006-87-OAR]
RIN 2060-AT02

National Emission Standards for Hazardous Air Pollutants: Generic
Maximum Achievable Control Technology Standards Residual Risk and
Technology Review for Ethylene Production

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This action finalizes the residual risk and technology review
(RTR) conducted for the Ethylene Production source category regulated
under National Emission Standards for Hazardous Air Pollutants
(NESHAP). In addition, the U.S. Environmental Protection Agency (EPA)
is taking final action to correct and clarify regulatory provisions
related to emissions during periods of startup, shutdown, and
malfunction (SSM), including removing general exemptions for periods of
SSM, adding work practice standards for periods of SSM where
appropriate, and clarifying regulatory provisions for certain vent
control bypasses. The EPA is also taking final action to revise
requirements for heat exchange systems; add monitoring and operational
requirements for flares; add provisions for electronic reporting of
performance test results and other reports; and include other technical
corrections to improve consistency and clarity. We estimate that these
final amendments will reduce hazardous air pollutants (HAP) emissions
from this source category by 29 tons per year (tpy) and reduce excess
emissions of HAP from flares by an additional 1,430 tpy.

DATES: This final rule is effective on July 6, 2020. The incorporation
by reference (IBR) of certain publications listed in the rule is
approved by the Director of the Federal Register as of July 6, 2020.

ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OAR-2017-0357. 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 (CBI) or other information whose disclosure is restricted
by statute. Certain other material, such as copyrighted material, is
not placed on the internet and will be publicly available only in hard
copy form. Publicly available docket materials are available either
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<PHONE_NUMBER>, and the telephone number for the EPA Docket Center
is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: For questions about this final action,
contact Mr. Andrew Bouchard, Sector Policies and Programs Division
(E143-01), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711; telephone number:<PHONE_NUMBER>; and email address:
<EMAIL_ADDRESS>For specific information regarding the risk
modeling methodology, contact Mr. Mark Morris, Health and Environmental
Impacts Division (C539-02), Office of Air Quality Planning and
Standards, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina 27711; telephone number:<PHONE_NUMBER>; and email
address<EMAIL_ADDRESS>For information about the applicability
of the NESHAP to a particular entity, contact Ms. Marcia Mia, Office of
Enforcement and Compliance Assurance, U.S. Environmental Protection
Agency, WJC South Building, 1200 Pennsylvania Ave. NW, Washington, DC
20460; telephone number:<PHONE_NUMBER>; and email address:
<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:
    Preamble acronyms and abbreviations. We use multiple acronyms and
terms in this preamble. While this list may not be exhaustive, to ease
the reading of this preamble and for reference purposes, the EPA
defines the following terms and acronyms here:

ACC American Chemistry Council
APCD air pollution control device
ASME American Society of Mechanical Engineers
BAAQMD Bay Area Air Quality Management District
BTF beyond-the-floor
Btu/scf British thermal units per standard cubic foot
CAA Clean Air Act
CBI Confidential Business Information
CDX Central Data Exchange
CEDRI Compliance and Emissions Data Reporting Interface
CFR Code of Federal Regulations
CO2 carbon dioxide
CRA Congressional Review Act
EFR external floating roof
EMACT Ethylene Production MACT
EPA Environmental Protection Agency
FTIR Fourier transform infrared spectrometry
gpm gallons per minute
GMACT Generic Maximum Achievable Control Technology
HAP hazardous air pollutant(s)
HI hazard index
HQ hazard quotient
IBR incorporation by reference
ICR Information Collection Request
IFR internal floating roof
km kilometer
kPa kilopascals
LDAR leak detection and repair
LEL lower explosive limit
MACT maximum achievable control technology
m\3\ cubic meter
Mg/yr megagrams per year
MIR maximum individual risk
MTVP maximum true vapor pressure
NAICS North American Industry Classification System
NESHAP national emission standards for hazardous air pollutants
NHVcz net heating value in the combustion zone gas
NHVvgnet heating value in the vent gas
NOCS Notification of Compliance Status
NPDES National Pollutant Discharge Elimination System
NRDC Natural Resources Defense Council
NTTAA National Technology Transfer and Advancement Act
OMB Office of Management and Budget
POM polycyclic organic matter
ppm parts per million
ppmv parts per million by volume
PRA Paperwork Reduction Act
PRD pressure relief device(s)
psig pounds per square inch gauge
REL reference exposure level
RFA Regulatory Flexibility Act
RTR residual risk and technology review
SCAQMD South Coast Air Quality Management District
SSM startup, shutdown, and malfunction
TAC Texas Administrative Code
TCEQ Texas Commission on Environmental Quality
The Court United States Court of Appeals for the District of
Columbia Circuit
TOSHI target organ-specific hazard index
tpy tons per year
UMRA Unfunded Mandates Reform Act
VCS voluntary consensus standards
VOC volatile organic compound(s)

    Background information. On October 9, 2019, the EPA proposed
revisions to the Generic Maximum Achievable Control Technology (GMACT)
Standards NESHAP based on our RTR for the Ethylene Production source
category. In this action, we are finalizing decisions and revisions for
the rule. We summarize some of the more significant comments we timely
received regarding the proposed rule and provide our responses in this
preamble. A summary of all other public comments on the proposal and
the EPA's responses to those comments is available in the

Summary of Public Comments and Responses for Risk and Technology Review
for Ethylene Production, in Docket ID No. EPA-HQ-OAR-2017-0357. A
``tracked 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 Ethylene Production source category and how does
the NESHAP regulate HAP emissions from the source category?
    C. What changes did we propose for the Ethylene Production
source category in our October 9, 2019, RTR proposal?
III. What is included in this final rule?
    A. What are the final rule amendments based on the risk review
for the Ethylene Production source category?
    B. What are the final rule amendments based on the technology
review for the Ethylene Production source category?
    C. What are the final rule amendments pursuant to CAA section
112(d)(2) and (3) for the Ethylene Production source category?
    D. What are the final rule amendments addressing emissions
during periods of SSM?
    E. What other changes have been made to the NESHAP?
    F. What are the effective and compliance dates of the standards?
IV. What is the rationale for our final decisions and amendments for
the Ethylene Production source category?
    A. Residual Risk Review for the Ethylene Production Source
Category
    B. Technology Review for the Ethylene Production Source Category
    C. Amendments Pursuant to CAA Section 112(d)(2) and (d)(3) for
the Ethylene Production Source Category
    D. Amendments Addressing Emissions During Periods of SSM
    E. Technical Amendments to the EMACT Standards
V. Summary of Cost, Environmental, and Economic Impacts and
Additional Analyses Conducted
    A. What are the affected facilities?
    B. What are the air quality impacts?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What analysis of environmental justice did we conduct?
    F. What analysis of children's environmental health did we
conduct?
VI. Statutory and Executive Order Reviews
    A. Executive Orders 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Executive Order 13771: Reducing Regulations and Controlling
Regulatory Costs
    C. Paperwork Reduction Act (PRA)
    D. Regulatory Flexibility Act (RFA)
    E. Unfunded Mandates Reform Act (UMRA)
    F. Executive Order 13132: Federalism
    G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    H. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    J. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR part 51
    K. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
    L. 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
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          Source category                  NESHAP         NAICS \1\ code
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Ethylene Production...............  GMACT Standards.....          325110
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\1\ North American 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-air-pollution/acetal-resins-acrylic-modacrylic-fibers-carbon-black-hydrogen.
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-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous. 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 the 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 September 4, 2020. 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 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 tpy or
more, or 25 tpy or more of any combination of HAP. For major sources,
these standards are commonly referred to as maximum achievable control
technology (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 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 best-
performing 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). 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 84 FR 54278, October 9, 2019.
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    \1\ The Court has affirmed this approach of implementing CAA
section 112(f)(2)(A): NRDC v. EPA, 529 F.3d 1077, 1083 (DC Cir.
2008) (``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.'').
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B. What is the Ethylene Production source category and how does the
NESHAP regulate HAP emissions from the source category?

    The Ethylene Production MACT standards (herein called the EMACT
standards) for the Ethylene Production source category are contained in
the GMACT NESHAP which also includes MACT standards for several other
source categories. The EMACT standards were promulgated on July 12,
2002 (67 FR 46258), and codified at 40 CFR part 63, subparts XX and YY.
The EMACT standards regulate HAP emissions from ethylene production
units located at major sources. An ethylene production unit is a
chemical manufacturing process unit in which ethylene and/or propylene
are produced by separation from petroleum refining process streams or
by subjecting hydrocarbons to high temperatures in the presence of
steam. The EMACT defines the affected source as all storage vessels,
ethylene process vents, transfer racks, equipment, waste streams, heat
exchange systems, and ethylene cracking furnaces and associated
decoking operations that are associated with each ethylene production
unit located at a major source as defined in CAA section 112(a).
    As of January 1, 2017, there were 26 facilities in operation and
subject to the EMACT standards. We are also aware of the expansion and
construction of several facilities. Based upon this anticipated growth
for the Ethylene Production source category, we estimate that a total
of 31 facilities will ultimately be subject to the EMACT standards and
complying with this final rule over the course of the next 3 years. The
source category and the EMACT standards are further described in the
October 9, 2019, RTR proposal. See 84 FR 54278.

C. What changes did we propose for the Ethylene Production source
category in our October 9, 2019, RTR proposal?

    On October 9, 2019, the EPA published a proposed rule in the
Federal Register for the EMACT standards of the GMACT NESHAP, 40 CFR
part 63, subparts XX and YY, that took into consideration the RTR
analyses. We proposed to find that the risks from the source category
are acceptable, the current standards provide an ample margin of safety
to protect public health, and more stringent standards are not
necessary to prevent an adverse environmental effect. In addition,
pursuant to the technology review for the Ethylene Production source
category, we proposed that no revisions to the current standards are
necessary for ethylene process vents, transfer racks, equipment leaks,
and waste streams; however, we did propose changes for storage vessels
and heat exchanger systems. We proposed revisions to the storage
vessels control applicability requirements, pursuant to CAA section
112(d)(6), to tighten both the threshold for maximum true vapor
pressure (MTVP) of total organic HAP (i.e., decreasing it from 3.4
kilopascals (kPa) or greater to 0.69 kPa or greater) and the threshold
for storage vessel capacity (i.e., decreasing it from 95 cubic meter

(m\3\) to 59 m\3\) and to require storage vessels meeting these
criteria to reduce emissions of total organic HAP by 98 weight-percent
or use a floating roof storage vessel subject to the requirements of 40
CFR part 63, subpart WW. In addition, we proposed revisions to the heat
exchange system requirements, pursuant to CAA section 112(d)(6), to
require owners or operators to use the Modified El Paso Method and
repair leaks of total strippable hydrocarbon concentration (as methane)
in the stripping gas of 6.2 parts per million by volume (ppmv) or
greater.
    We also proposed the following amendments:
     Revisions to the operating and monitoring requirements for
flares used as air pollution control devices (APCDs), pursuant to CAA
section 112(d)(2) and (3);
     requirements and clarifications for periods of SSM and
bypasses, including for pressure relief device(s) (PRD) releases,
bypass lines on closed vent systems, in situ sampling systems,
maintenance activities, and certain gaseous streams routed to a fuel
gas system, pursuant to CAA section 112(d)(2) and (3);
     work practice standards for decoking ethylene cracking
furnaces (i.e., minimizing emissions from the coke combustion
activities in an ethylene cracking furnace), pursuant to CAA section
112(d)(2) and (3);
     revisions to the SSM provisions of the NESHAP (in addition
to those related to flares, vent control bypasses, or ethylene cracking
furnace decoking operations) in order to ensure that they are
consistent with the Court decision in Sierra Club v. EPA, 551 F. 3d
1019 (DC Cir. 2008), which vacated two provisions that exempted source
owners and operators from the requirement to comply with otherwise
applicable CAA section 112(d) emission standards during periods of SSM;
     a requirement for electronic submittal of performance test
results and reports, and Notification of Compliance Status (NOCS)
reports;
     removal of certain exemptions for once-through heat
exchange systems;
     overlap provisions for equipment at ethylene production
facilities subject to both the EMACT standards and synthetic organic
chemicals manufacturing equipment leak standards at 40 CFR part 60,
subpart VVa;
     IBR of an alternative test method for EPA Methods 3A and
3B (for the manual procedures only and not the instrumental
procedures);
     IBR of an alternative test method for EPA Method 18 (with
caveats);
     IBR of an alternative test method for EPA Method 320 (with
caveats); and
     several minor editorial and technical changes in the
subpart.

III. What is included in this final rule?

    This action finalizes the EPA's determinations pursuant to the RTR
provisions of CAA section 112 for the Ethylene Production source
category and amends the EMACT standards based on those determinations.
This action also finalizes other changes to the NESHAP, including
adding requirements and clarifications for periods of SSM and bypasses;
revisions to the operating and monitoring requirements for flares used
as APCDs; adding provisions for electronic reporting of performance
test results and reports, NOCS reports, and Periodic Reports; and other
minor editorial and technical changes. This action also reflects
several changes to the October 9, 2019 RTR proposal in consideration of
comments received during the public comment period as described in
section IV of this preamble.

A. What are the final rule amendments based on the risk review for the
Ethylene Production source category?

    This section describes the final amendments to the EMACT standards
being promulgated pursuant to CAA section 112(f). The EPA proposed no
changes to the EMACT standards based on the risk reviews conducted
pursuant to CAA section 112(f). In this action, we are finalizing our
proposed determination that risks from this source category are
acceptable, and that the standards provide an ample margin of safety to
protect public health and prevent an adverse environmental effect.
Section IV.A.3 of this preamble provides a summary of key comments we
received regarding risk review and our responses.

B. What are the final rule amendments based on the technology review
for the Ethylene Production source category?

    The EPA is finalizing its proposed determination in the technology
review that there are no developments in practices, processes, and
control technologies that warrant revisions to the EMACT standards for
process vents, transfer racks, equipment leaks, and waste streams in
this source category. Therefore, we are not finalizing revisions to the
EMACT standards for these emission sources under CAA section 112(d)(6).
Also, based on comments received on the proposed rulemaking, we are not
finalizing the proposed revisions to the EMACT standards for storage
vessels under CAA section 112(d)(6) to tighten the control
applicability thresholds for MTVP of total organic HAP (i.e.,
decreasing it from 3.4 kPa or greater to 0.69 kPa or greater) and
storage vessel capacity (i.e., decreasing it from 95 m\3\ to 59 m\3\).
    For heat exchange systems, we determined that there are
developments in practices, processes, and control technologies that
warrant revisions to the EMACT standards for this source category.
Therefore, to satisfy the requirements of CAA section 112(d)(6), we are
revising the EMACT standards, consistent with the October 9, 2019, RTR
proposal, to include revisions to the heat exchange system requirements
to require owners or operators to use the Modified El Paso Method and
repair leaks of total strippable hydrocarbon concentration (as methane)
in the stripping gas of 6.2 ppmv or greater. In addition, based on
comments received on the proposed rulemaking, we are also including an
alternative mass-based leak action level of total strippable
hydrocarbon equal to or greater than 0.18 kilograms per hour for heat
exchange systems with a recirculation rate of 10,000 gallons per minute
(gpm) or less.
    Section IV.B.3 of this preamble provides a summary of key comments
we received on the technology review and our responses.

C. What are the final rule amendments pursuant to CAA section 112(d)(2)
and (3) for the Ethylene Production source category?

    Consistent with Sierra Club v. EPA 551 F. 3d 1019 (D.C. Cir. 2008)
and the October 9, 2019, RTR proposal, we are revising monitoring and
operational requirements for flares to ensure that ethylene production
facilities that use flares as APCDs meet the EMACT standards at all
times when controlling HAP emissions. In addition, we are adding
provisions and clarifications for periods of SSM and bypasses,
including PRD releases, bypass lines on closed vent systems, in situ
sampling systems, maintenance activities, and certain gaseous streams
routed to a fuel gas system to ensure that CAA section 112 standards
apply continuously. Also, for the same reason, we are adopting the
proposed decoking operations work practice standards into the final
rule with only minor changes, such as adding delay of repair provisions
to the flame impingement inspection requirements, adding clarifying
text to the carbon dioxide (CO2) monitoring, coil outlet
temperature monitoring, air removal, and radiant tube(s) treatment
requirements, and removing unnecessary recordkeeping associated

with the time each isolation valve inspection is performed and the
results of that inspection even if no problem was found. For details
about these minor changes, refer to Section 6.7 of the document,
Summary of Public Comments and Responses for the Risk and Technology
Reviews for the Ethylene Production Source Category, available in the
docket for this action.
    Lastly, based on comments received on the proposed rulemaking, we
are adding a separate standard for storage vessel degassing for storage
vessels subject to the control requirements in Table 7 to 40 CFR
63.1103(e)(3)(b) and (e)(3)(c).
    Section IV.C.3 of this preamble provides a summary of key comments
we received on the CAA section 112(d)(2) and (3) provisions and our
responses.

D. What are the final rule amendments addressing emissions during
periods of SSM?

    We are finalizing the proposed amendments to the EMACT standards to
remove and revise provisions related to SSM. In its 2008 decision in
Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008), the Court vacated
portions of two provisions in the EPA's CAA section 112 regulations
governing the emissions of HAP during periods of SSM. Specifically, the
Court vacated the SSM exemption contained in 40 CFR 63.6(f)(1) and
(h)(1), holding that under section 302(k) of the CAA, emissions
standards or limitations must be continuous in nature and that the SSM
exemption violates the CAA's requirement that some CAA section 112
standards apply continuously. As detailed in section IV.E.1 of the
proposal preamble, the Ethylene Production NESHAP requires that
standards apply at all times (see 40 CFR 63.1108(a)(4)(i)), consistent
with the Court decision in Sierra Club v. EPA, 551 F. 3d 1019 (D.C.
Cir. 2008). We determined that facilities in this source category can
generally meet the applicable EMACT standards at all times, including
periods of startup and shutdown. As discussed in the proposal preamble,
the EPA interprets CAA section 112 as not requiring emissions that
occur during periods of malfunction to be factored into development of
CAA section 112 standards, although the EPA has the discretion to set
standards for malfunctions where feasible. Where appropriate, and as
discussed in section III.C of this preamble, we are also finalizing
alternative standards for certain emission points during periods of SSM
to ensure a continuous CAA section 112 standard applies ``at all
times.'' Other than for those specific emission points discussed in
section III.C of this preamble, the EPA determined that no additional
standards are needed to address emissions during periods of SSM.
    We are also finalizing, as proposed, eliminating SSM exemptions for
waste streams at facilities with a total annual benzene less than 10
megagrams per year (Mg/yr) and amending language in the definitions of
``dilution steam blowdown waste stream'' and ``spent caustic waste
stream'' at 40 CFR 63.1082(b) to remove the exclusion for streams
generated from sampling, maintenance activities, or shutdown purges. In
addition, we are finalizing a revision to the performance testing
requirements at 40 CFR 63.1108(b)(4)(ii)(B). The final performance
testing provisions do not include the language that precludes startup
and shutdown periods from being considered ``representative'' for
purposes of performance testing, and instead allows performance testing
during periods of startup or shutdown if specified by the
Administrator. However, the final performance testing provisions
prohibit performance testing during malfunctions because these
conditions are not representative of normal operating conditions. The
final rule also requires that operators maintain records to document
that operating conditions during the test represent normal operations.
    The legal rationale and detailed changes for SSM periods that we
are finalizing here are set forth in the proposed rule. See 84 FR
54278, October 9, 2019. Also, based on comments received during the
public comment period, we are revising 40 CFR 63.1103(e)(9) to
sufficiently address the SSM exemption provisions from subparts
referenced by the EMACT standards. For example, in addition to what we
proposed, we are also clarifying that the certain referenced provisions
do not apply when demonstrating compliance with the EMACT standards,
such as phrases like ``other than a start-up, shutdown, or
malfunction'' in the recordkeeping and reporting requirements of 40 CFR
63, subparts SS and UU. We are also not removing as proposed the term
``breakdowns'' in 40 CFR 63.998(b)(2)(i) as well as 40 CFR
63.998(d)(1)(ii) in its entirety.
    Section IV.D.3 of this preamble provides a summary of key comments
we received on the SSM provisions and our responses.

E. What other changes have been made to the NESHAP?

    This rule also finalizes, as proposed, revisions to several other
NESHAP requirements. We describe these revisions in this section as
well as other revisions that have changed since proposal. To increase
the ease and efficiency of data submittal and data accessibility, we
are finalizing, as proposed, a requirement that owners and operators of
facilities in the Ethylene Production source category submit electronic
copies of certain required performance test results and reports and
NOCS reports through the EPA's Central Data Exchange (CDX) website
using an electronic performance test report tool called the Electronic
Reporting Tool. In addition, in the final rule, we are correcting an
error to clarify that Periodic Reports must also be submitted
electronically (i.e., through the EPA's CDX using the appropriate
electronic report template for this subpart) beginning no later than
the compliance dates specified in 40 CFR 63.1102(c) or once the report
template has been available on the Compliance and Emissions Data
Reporting Interface (CEDRI) website for at least 1 year, whichever date
is later. Furthermore, we are finalizing, as proposed, provisions that
allow facility operators the ability to seek extensions for submitting
electronic reports for circumstances beyond the control of the
facility, i.e., for a possible outage in the CDX or CEDRI or for a
force majeure event in the time just prior to a report's due date, as
well as the process to assert such a claim.
    To correct a disconnect between having a National Pollutant
Discharge Elimination System (NPDES) permit that meets certain
allowable discharge limits at the discharge point of a facility (e.g.,
outfall) and being able to adequately identify a leak, we are
finalizing, as proposed, the removal of certain exemptions for once-
through heat exchange systems to comply with cooling water monitoring
requirements.\2\ Further, based on comments received on the proposed
rulemaking, we are clarifying that the calibration drift assessment
provisions at 40 CFR 60.485a(b)(2) apply only if the owner or

operator is subject to those requirements in 40 CFR part 60, subpart
VVa [see the 40 CFR part 60, subpart VVa overlap provisions in the
final rule at 40 CFR 63.1100(g)(4)(iii)].
---------------------------------------------------------------------------

    \2\ Cooling water from a once-through heat exchange system at a
petrochemical plant can be mixed with other sources of water (e.g.,
cooling water used in once-through heat exchange systems in non-
ethylene source categories, stormwater, treated wastewater, etc.) in
sewers, trenches, and ponds prior to discharge from the plant. If
this point of discharge from the plant is into a ``water of the
United States,'' then the facility is required to have a NPDES
permit and to meet certain pollutant discharge limits.
---------------------------------------------------------------------------

    We are finalizing all of the revisions that we proposed for
clarifying text or correcting typographical errors, grammatical errors,
and cross-reference errors. These editorial corrections and
clarifications are summarized in Table 9 of the proposal. See 84 FR
54278, October 9, 2019. We are also including several additional minor
clarifying edits in the final rule based on comments received during
the public comment period. We did not receive many substantive comments
on these other amendments in the Ethylene Production RTR proposal. The
comments and our specific responses to these items can be found in the
document, Summary of Public Comments and Responses for the Risk and
Technology Reviews for the Ethylene Production Source Category,
available in the docket for this action.

F. What are the effective and compliance dates of the standards?

    The revisions to the EMACT standards being promulgated in this
action are effective on July 6, 2020. From our assessment of the
timeframe needed for implementing the entirety of the revised
requirements (see 84 FR 54278, October 9, 2019), the EPA proposed a
period of 3 years to be the most expeditious compliance period
practicable. Although opposing comments regarding the proposed
compliance dates were received during the public comment period, we are
finalizing the 3-year compliance period as proposed. Amendments to
EMACT standards for adoption under CAA sections 112(d)(2) and (3) and
112(d)(6) are subject to the compliance deadlines outlined in the CAA
under section 112(i). For existing sources, CAA section 112(i) provides
that the compliance date shall be as expeditiously as practicable, but
no later than 3 years after the effective date of the standard. For new
sources, compliance is required by the effective date of the final
amendments or upon startup, whichever is later. As explained in the
preamble to the proposed rule (84 FR 54278, October 9, 2019), the EPA
recognizes the confusion that multiple different compliance dates for
individual requirements would create and the additional burden such an
assortment of dates would impose; and from our assessment of the
timeframe needed for compliance with the entirety of the revised
requirements, the EPA considers a period of 3 years after the effective
date of the final rule to be the most expeditious compliance period
practicable. Furthermore, as discussed in sections III and IV of this
preamble, we are adding separate work practice standards to the final
rule for the following SSM activities/events: (1) Periods of SSM for
when flares are used as an APCD, (2) periods of SSM for certain vent
streams (i.e. PRD releases and maintenance vents), (3) vent control
bypasses for certain vent streams (i.e., closed vent systems containing
bypass lines, in situ sampling systems, and flares connected to fuel
gas systems), and (4) decoking operations for ethylene cracking
furnaces. The provisions being finalized are similar to the
requirements promulgated in the Petroleum Refinery NESHAP. As we
discovered during the Petroleum Refinery NESHAP rulemaking, the
challenges faced by affected sources in complying with these
requirements necessitated additional compliance time from what was
promulgated, eventually having to move the original compliance date of
these provisions from February 1, 2016, to August 1, 2018, an
additional 2 and a half years.\3\ Therefore the 3 year compliance date
that was proposed for the EMACT standards provides a consistent time
allowance to affected sources as was needed for Petroleum Refineries to
fully implement the work practice standards. Thus, the compliance date
of the final amendments for all existing affected sources, and all new
affected sources that commence construction or reconstruction after
December 6, 2000, and on or before October 9, 2019, is no later than
July 6, 2023, or upon startup, whichever is later. The compliance date
of the final amendments for all ethylene production new affected
sources that commenced construction or reconstruction after October 9,
2019, is the effective date of these final rule amendments to the EMACT
standards of July 6, 2020, or upon startup, whichever is later.
---------------------------------------------------------------------------

    \3\ https://www.epa.gov/sites/production/files/2018-07/documents/petrefinery_compliance_ext_factsheet.pdf.
---------------------------------------------------------------------------

IV. What is the rationale for our final decisions and amendments for
the Ethylene Production source category?

    For each issue, this section provides a description of what we
proposed and what we are finalizing for the issue, the EPA's rationale
for the final decisions and amendments, and a summary of key comments
and responses. For all comments not discussed in this preamble, comment
summaries and the EPA's responses can be found in the comment summary
and response document available in the docket.

A. Residual Risk Review for the Ethylene Production Source Category

1. What did we propose pursuant to CAA section 112(f) for the Ethylene
Production source category?
    Pursuant to CAA section 112(f), the EPA conducted a residual risk
review and presented the results of this review, along with our
proposed decisions regarding risk acceptability and ample margin of
safety, in the October 9, 2019, proposed rule for 40 CFR part 63,
subparts XX and YY (84 FR 54278). The results of the risk assessment
for the proposal are presented briefly in Table 2 of this preamble.
More detail is in the residual risk technical support document,
Residual Risk Assessment for the Ethylene Production Source Category in
Support of the 2019 Risk and Technology Review Proposed Rule, which is
available in the docket for this rulemaking.

                                                                 Table 2--Ethylene Production Inhalation Risk Assessment Results
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                      Maximum  individual  cancer     Estimated population at  increased       Estimated annual  cancer       Maximum chronic  noncancer     Maximum  screening
                                       risk  (in 1 million) \2\        risk of  cancer >= 1-in-1 million      incidence  (cases per year)              TOSHI \3\             acute noncancer HQ
                                   ----------------------------------------------------------------------------------------------------------------------------------------          \4\
                                            Based on . . .                      Based on . . .                      Based on . . .                  Based on . . .         ---------------------
     Number of facilities \1\      ----------------------------------------------------------------------------------------------------------------------------------------
                                        Actual         Allowable                                                Actual         Allowable        Actual         Allowable      Based on  actual
                                       emissions       emissions     Actual  emissions       Allowable         emissions       emissions       emissions       emissions      emissions  level
                                         level           level             level         emissions  level        level           level           level           level
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
31................................             100             100  2.8 million.......  4.6 million.......             0.1             0.2               1               1  HQREL = <1
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Number of facilities evaluated in the risk analysis.
\2\ Maximum individual excess lifetime cancer risk due to HAP emissions from the source category. There is only one census block, and one person, at this risk level.
\3\ Maximum target organ-specific hazard index (TOSHI). The target organ systems with the highest TOSHI for the source category are neurological and reproductive. The respiratory TOSHI was
  calculated using the California EPA chronic reference exposure level (REL) for acrolein.
\4\ The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of hazard quotient (HQ) values. HQ values shown use the lowest
  available acute threshold value, which in most cases is the REL. When an HQ exceeds 1, we also show the HQ using the next lowest available acute dose-response value.

    Using actual emissions data, the results of the proposed inhalation
risk assessment, as shown in Table 2 of this preamble, indicate the
estimated cancer maximum individual risk (MIR) is 100-in-1 million,
with naphthalene and benzene as the major contributors to the risk.
There is only one census block, and one person, at this risk level. The
second-highest facility cancer risk is 30-in-1 million. At proposal,
the total estimated cancer incidence from this source category was
estimated to be 0.1 excess cancer cases per year, or one excess case in
every 10 years. Approximately 2.8 million people were estimated to have
cancer risks above 1-in-1 million from HAP emitted from the facilities
in this source category. At proposal, the estimated maximum chronic
noncancer TOSHI for the source category was 1 (neurological and
respiratory) driven by emissions of manganese and epichlorohydrin.
    Using the MACT-allowable emissions, the risk results at proposal
for the inhalation risk assessment indicated that the estimated cancer
MIR was 100-in-1 million with naphthalene and benzene emissions driving
the risks, and that the estimated maximum chronic noncancer TOSHI was 1
with manganese and epichlorohydrin as the major contributors to the
TOSHI. At proposal, the total estimated cancer incidence from this
source category considering allowable emissions was 0.2 excess cancer
cases per year or 1 excess case in every 5 years. Based on allowable
emission rates, 4.6 million people were estimated to have cancer risks
above 1-in-1 million.
    As shown in Table 2 of this preamble, the reasonable worst-case
acute HQ (based on the REL) at proposal was less than 1. This value is
the highest HQ that is outside facility boundaries. No facilities were
estimated to have an HQ greater than or equal to 1 based on any
benchmark (REL, acute exposure guideline level, or emergency response
planning guidelines). In addition, at proposal, we identified emissions
of arsenic compounds, cadmium compounds, mercury compounds, and
polycyclic organic matter (POM), all HAP known to be persistent and
bio-accumulative in the environment. The multipathway risk screening
assessment resulted in a maximum Tier 2 cancer screening value of 30
for arsenic and a maximum Tier 3 noncancer screening value of 2 for
mercury compounds. Based on facility-specific analyses performed for
mercury for other source categories, we concluded that such analyses
would reduce the mercury screening value to 1 or lower. In addition, a
screening-level evaluation of the potential adverse environmental risk
associated with emissions of arsenic, cadmium, hydrochloric acid,
hydrofluoric acid, lead, mercury, and POMs indicated that no ecological
benchmarks were exceeded.
    We weighed all health risk factors, including those shown in Table
2 of this preamble, in our risk acceptability determination and
proposed that the risks posed by the Ethylene Production source
category are acceptable (section IV.C.1 of proposal preamble, 84 FR
54311, October 9, 2019).
    We then considered whether the existing EMACT standards provide an
ample margin of safety to protect public health and whether, taking
into consideration costs, energy, safety, and other relevant factors,
more stringent standards are required to prevent an adverse
environmental effect. In considering whether the standards are required
to provide an ample margin of safety to protect public health, we
considered the same risk factors that we considered for our
acceptability determination and also considered the costs,
technological feasibility, and other relevant factors related to
emissions control options that might reduce risk associated with
emissions from the source category. We proposed that additional
emissions controls for the Ethylene Production source category are not
necessary to provide an ample margin of safety to protect public health
and that more stringent standards are not necessary to prevent an
adverse environmental effect (section IV.C.2 of proposal preamble, 84
FR 54312, October 9, 2019).
    We also evaluate risk from whole facility emissions in order to
help put the risks in context. Whole facility (or ``facility-wide'')
emissions include those regulated under this source category plus all
other emissions generated at each facility. The results of the chronic
inhalation cancer risk assessment based on facility-wide emissions are
more uncertain and rely on the quality of the emissions data collected
for source categories outside this regulatory review. These emissions
sources may not undergo the same level of data quality review as those
being assessed in this regulatory assessment. The estimated maximum
lifetime individual cancer risk based on facility-wide emissions is
2,000-in-1 million, with ethylene oxide from non-category (non-ethylene
production process) emissions driving the risk. The total estimated
cancer incidence based on facility-wide emissions is 1 excess cancer
case per year. Approximately 6,500,000 people are estimated to have
cancer risks above 1-in-1 million from HAP emitted from all sources at
the facilities in this source category. The estimated maximum chronic
noncancer hazard index (HI) based on facility-wide emissions is 4 (for
the respiratory HI), driven by emissions of chlorine from non-category
(non-ethylene production process) emissions. Approximately 200 people
are estimated to be exposed to noncancer HI levels above 1.

2. How did the risk review change for the Ethylene Production source
category?
    We have not changed any aspect of the risk assessment since the
October 9, 2019, RTR proposal for the Ethylene Production source
category.
3. What key comments did we receive on the risk review, and what are
our responses?
    We received comments in support of and against the proposed
residual risk review and our determination that no revisions were
warranted under CAA section 112(f)(2) for the Ethylene Production
source category. Generally, the comments that were not supportive of
the determination from the risk reviews suggested changes to the
underlying risk assessment methodology. For example, some commenters
stated that the 100-in-1 million lifetime cancer risk cannot be
considered safe or ``acceptable,'' and the EPA should include emissions
outside of the source categories in question in the risk assessment and
assume that pollutants with noncancer health risks have no safe level
of exposure. After review of all the comments received, we determined
that no changes were necessary. The comments and our specific responses
can be found in the document, Summary of Public Comments and Responses
for the Risk and Technology Reviews for the Ethylene Production Source
Category, available in the docket for this action.
4. What is the rationale for our final approach and final decisions for
the risk review?
    As noted in our proposal, the EPA sets standards under CAA section
112(f)(2) using ``a two-step standard-setting approach, with an
analytical first step to determine an `acceptable risk' that considers
all health information, including risk estimation uncertainty, and
includes a presumptive limit on MIR of approximately 1-in-10 thousand''
(84 FR 54278, October 9, 2019; see also 54 FR 38045, September 9,
1989). We weigh all health risk factors in our risk acceptability
determination, including the cancer MIR, cancer incidence, the maximum
cancer TOSHI, the maximum acute noncancer HQ, the extent of noncancer
risks, the distribution of cancer and noncancer risks in the exposed
population, multipathway risks, and the risk estimation uncertainties.
    Since proposal, neither the risk assessment nor our determinations
regarding risk acceptability, ample margin of safety, or adverse
environmental effects have changed. For the reasons explained in the
proposed rule, we determined that the risks from the Ethylene
Production source category are acceptable, the current standards
provide an ample margin of safety to protect public health, and more
stringent standards are not necessary to prevent an adverse
environmental effect. Therefore, we are not revising the EMACT
standards to require additional controls pursuant to CAA section
112(f)(2) based on the residual risk review, and we are readopting the
existing standards under CAA section 112(f)(2).

B. Technology Review for the Ethylene Production Source Category

1. What did we propose pursuant to CAA section 112(d)(6) for the
Ethylene Production source category?
    Pursuant to CAA section 112(d)(6), the EPA proposed to conclude
that no revisions to the current EMACT standards are necessary for
ethylene process vents, transfer racks, equipment leaks, and waste
streams (sections IV.D.2 through IV.D.5 of proposal preamble, 84 FR
54314, October 9, 2019). We did not find any developments (since
promulgation of the original NESHAP) in practices, processes, and
control technologies that could be applied to ethylene process vents
and that could be used to reduce emissions from ethylene production
facilities. We also did not identify any developments in work
practices, pollution prevention techniques, or process changes that
could achieve emission reductions from ethylene process vents. For
transfer racks, we identified one emission reduction option, at
proposal, to revise the transfer rack applicability threshold (for
volumetric throughput of liquid loaded) from 76 m\3\ per day to 1.8
m\3\ per day to reflect the more stringent applicability threshold of
other chemical sector standards that regulate emissions from transfer
rack operations (i.e., 40 CFR part 63, subparts F and G and 40 CFR part
63, subpart FFFF). At proposal, we also identified two developments in
leak detection and repair (LDAR) practices and processes for equipment
leaks: (1) Lowering the leak definition for valves in gas and vapor
service or in light liquid service from 500 parts per million (ppm) to
100 ppm and (2) lowering the leak definition for pumps in light liquid
service from 1,000 ppm to 500 ppm. In addition, we identified two
emission reduction options, at proposal, for waste streams: (1)
specific performance parameters for an enhanced biological unit beyond
those required in the Benzene Waste Operations NESHAP and (2) treatment
of wastewater streams with a volatile organic compounds (VOC) content
of 750 ppmv or higher by steam stripping prior to any other treatment
process for facilities with high organic loading rates (i.e.,
facilities with total annualized benzene quantity of 10 Mg/yr or more).
However, based on the costs and emission reductions for each of the
proposed options (for transfer racks, equipment leaks, and waste
streams), we considered none of these options to be cost effective for
reducing emissions from these emission sources at ethylene production
units, and we proposed that it is not necessary to revise the EMACT
standards for these emission sources pursuant to CAA section 112(d)(6).
    Also, pursuant to CAA section 112(d)(6), we proposed revisions to
the current EMACT standards for storage vessels and heat exchange
systems (sections IV.D.1 and IV.D.6 of proposal preamble, 84 FR 54314,
October 9, 2019). For storage vessels, we proposed tightening both the
applicability threshold for MTVP of total organic HAP (i.e., decreasing
it from 3.4 kPa or greater to 0.69 kPa or greater) and the
applicability threshold for storage vessel capacity (i.e., decreasing
it from 95 m\3\ to 59 m\3\) in Table 7 at 40 CFR 63.1103(e)(3)(a)(1)
and 40 CFR 63.1103(e)(3)(b)(1), respectively. For heat exchange
systems, we proposed to add a new provision, 40 CFR 63.1086(e), that
would require owners or operators to use the Modified El Paso Method to
monitor for leaks and to repair leaks of total strippable hydrocarbon
concentration (as methane) in the stripping gas of 6.2 ppmv or greater.
We also proposed to add a new provision, 40 CFR 63.1088(d),
establishing a delay of repair action level of total strippable
hydrocarbon concentration (as methane) in the stripping gas of 62 ppmv,
that if exceeded during leak monitoring, would require immediate repair
(i.e., the leak found cannot be put on delay of repair and would be
required to be repaired within 30 days of the monitoring event). This
would apply to both monitoring heat exchange systems and individual
heat exchangers by replacing the use of any 40 CFR part 136 water
sampling method with the Modified El Paso Method and removing the
option that allows for use of a surrogate indicator of leaks. Finally,
we proposed to add a new provision, 40 CFR 63.1087(c), requiring re-
monitoring at the monitoring location where a leak is identified to
ensure that any leaks found are fixed.

2. How did the technology review change for the Ethylene Production
source category?
    The EPA has not changed any aspect of the technology review for
process vents, transfer racks, equipment leaks, and waste streams since
the October 9, 2019, RTR proposal for the Ethylene Production source
category. However, based on comments received on the proposed
rulemaking, we are not finalizing the proposed revisions to the EMACT
standards for storage vessels under CAA section 112(d)(6) to tighten
the applicability threshold for MTVP of total organic HAP (i.e.,
decreasing it from 3.4 kPa or greater to 0.69 kPa or greater) and the
applicability threshold for storage vessel capacity (i.e., decreasing
it from 95 m\3\ to 59 m\3\). Moreover, although we are revising the
EMACT standards for heat exchange systems consistent with the October
9, 2019, RTR proposal, we are also including, based on comments
received on the proposed rulemaking, an alternative mass-based leak
action level of total strippable hydrocarbon equal to or greater than
0.18 kilograms per hour for heat exchange systems with a recirculation
rate of 10,000 gpm or less.
3. What key comments did we receive on the technology review, and what
are our responses?
    The EPA received comments in support of and against the proposed
technology review amendments and our determination that no revisions
were warranted under CAA section 112(d)(6) for process vents, transfer
racks, equipment leaks, and waste streams in the Ethylene Production
source category and that revisions were warranted for storage vessels
and heat exchange systems in the Ethylene Production source category.
Generally, for process vents, transfer racks, equipment leaks, and
waste streams, the comments were either supportive of the determination
that no cost-effective developments from the technology review were
found, or that the Agency should re-open and re-evaluate the MACT
standards for these emission sources and not consider cost in the
technology review for the emissions sources. Based on our review of the
comments received for process vents, transfer racks, equipment leaks,
and waste streams, we are finalizing our determination that no cost-
effective developments exist and that it is not necessary to revise
these emission standards under CAA section 112(d)(6).
    For storage vessels, the EPA received additional information from
commenters on material composition, storage vessels that would be
affected by the proposed option, and costs necessary for control of the
storage vessels that would be affected by the proposed control option.
After review of all the comments received, we determined that it is not
cost effective to revise the storage vessel control requirements and
are not finalizing revisions for this emissions source under CAA
section 112(d)(6).
    For heat exchange systems, the EPA received additional information
from commenters on costs necessary for control of these sources as well
as comments on a number of technical clarifications and allowance of
compliance with an alternative mass-based leak action level should the
EPA finalize the requirements for heat exchange systems. After review
of all the comments received, we determined that it is cost effective
to revise the heat exchange system requirements, and we are finalizing
revisions for this emissions source under CAA section 112(d)(6)
however, we are also including, based on comments received on the
proposed rulemaking, an alternative mass-based leak action level of
total strippable hydrocarbon equal to or greater than 0.18 kilograms
per hour for heat exchange systems with a recirculation rate of 10,000
gpm or less.
    This section provides comment and responses for the key comments
received regarding the technology review amendments we proposed for
storage vessels and heat exchange systems. Comment summaries and the
EPA's responses for additional issues raised regarding the proposed
requirements resulting from our technology review are in the document,
Summary of Public Comments and Responses for the Risk and Technology
Reviews for the Ethylene Production Source Category, available in the
docket for this action.
    Comment: We received comments in support of and against the
proposed changes to the storage vessel capacity and vapor pressure
thresholds and corresponding control requirements. Most of the
commenters opposed to the proposed requirements said the EPA's proposed
changes to the capacity and vapor pressure thresholds for control of
storage vessel emissions are not cost-effective. The commenters said
that based on their analysis and using the EPA percentages of annual
cost components (9.47-percent capital recovery, 5-percent maintenance,
4 percent for taxes, insurance, and administration, $380 per ton of VOC
recovered), the average capital cost for control is approximately $1.2
million per tank, the average annual cost is $216,000 per tank, and the
cost effectiveness of the control option is $108,000 per ton of VOC.
The commenters said that their estimates account for materials and
installation, in addition to the necessary cleaning and preparation
required to install the floating roof or make the necessary connections
to the closed vent system. The commenters asserted that degassing and
cleaning do not appear to be included in the EPA's cost calculation and
should be added as these are necessary steps to prepare the tanks for
modification and ensure worker safety. The commenter said that their
cost estimate is much higher than the EPA's estimate; and the
commenters contended the EPA's estimated capital investment for the
installation of an internal floating roof (IFR) on an existing fixed
roof tank is unrealistic and should be revised. The commenters stated
that at least one facility would install a new closed vent system to an
existing control device, instead of an IFR, due to more favorable
economics or site-specific constraints. The commenters said that the
cost of this closed vent system is approximately $825,000 per tank
(materials and installation). The commenters also provided certain
technical details and cost information that they claimed as CBI.
    Response: We are not finalizing the proposed requirements to
tighten the storage vessel capacity and MTVP thresholds in response to
comments and additional costs information that the EPA received on the
proposal. Specifically, we reviewed and agree with the additional
information submitted by commenters on the specific storage vessels
that would be affected (e.g., material composition and vapor pressure
data, costs to control those storage vessels, and estimated emissions
reductions). Importantly, the CBI submitted by one commenter provided
details showing that installation of an IFR was not an option for their
specific facility due to technical constraints. In addition, given that
the proposed option would result in 10 tpy of VOC reductions nationwide
(and lower emissions reductions for HAP) and cost over $1 million
annually, we find the control of storage vessels at $108,000 per ton
for VOC (and higher cost effectiveness for HAP) is not cost effective.
Further, the proposed option would only affect six of the approximately
248 storage vessels in the source category [assuming an average of
eight storage vessels per facility from the CAA section 114 Information
Collection Request (ICR) data] and would not meaningfully reduce
overall

emissions from the source category. Given all of this information, we
are not finalizing the proposed requirements to tighten the storage
vessel capacity and MTVP thresholds and are keeping the current MACT
level of control for storage vessels in place.
    Comment: A commenter stated that the proposed technology review
amendments do not represent MACT and noted three control options were
identified for storage vessels, but only one was adopted into the
proposed rule. The commenter emphasized that many new ethylene
production facilities are planned to be constructed or are under
construction and the EPA must address their HAP emissions by applying
the most stringent control technologies.
    Similarly, another commenter stated that it would be unlawful,
arbitrary, and capricious for the EPA not to set stronger standards for
emissions from storage vessels. The commenter stated that although the
EPA identified two other developments in technology for storage
vessels: (1) Requiring LDAR for fittings on fixed roof storage vessels
(e.g., access hatches) using EPA Method 21, and the use of liquid level
overfill warning monitors and roof landing warning monitors on storage
vessels with an IFR or external floating roof (EFR); and (2) the
conversion of EFRs to IFRs through use of geodesic domes, the EPA
declined to require these controls simply because the control options
were not cost effective. The commenter insisted that the EPA failed to
show why the cost-per-ton it found for storage vessel developments are
inappropriate and failed to show why further reductions are not
required to satisfy CAA sections 112(d)(6) and (f)(2). The commenter
noted the costs the EPA found ($6,120 per ton HAP to $44,100 per ton
HAP) are lower than other rules where the EPA determined the cost-per-
ton to be appropriate. As an example, the commenter cited the cost-per-
ton from secondary lead smelting that were considered reasonable,
ranging from $330,000 per ton to $1,500,000 per ton (77 FR 576, January
5, 2012). The commenter stated that because the EPA found higher cost-
reduction ratios appropriate, it is arbitrary and capricious for the
EPA not to require greater reductions for storage vessels, when they
are achievable and would provide more protection for public health, as
statutorily provided. The commenter asserted that several of these
developments are already widely in use or required by other regulatory
agencies. The commenter further argued that the EPA gives no
explanation for why the Agency considers ``incremental cost
effectiveness'' to be determinative rather than evaluating costs based
on ``HAP cost effectiveness'' as it does for other source types, such
as equipment leaks and waste streams.
    The commenter argued that the EPA's decision to make cost-per-ton
the standard-setting criterion and to choose a number it deems
unreasonable, without a rational explanation, is arbitrary and
capricious. The commenter stated the cost-per-ton of HAP reduction does
not indicate whether a stronger standard is feasible and does not
consider whether the industry could bear the costs of additional
controls. The commenter stated that the ethylene production industry
generated $50.8 billion in revenue in 2016 and the EPA cannot plausibly
claim that this industry cannot afford to implement the identified
storage vessel developments. The commenter noted that cost-per-ton says
nothing about health risk, and that a ton of HAP is a very large
amount. The commenter stated that the risk assessment for this source
category shows the pollutants emitted in ethylene production are known
to be hazardous at an exposure level of micrograms or less, and the
carcinogens emitted (e.g., benzene, formaldehyde, naphthalene) have no
safe level of exposure. In addition, the commenter asserted that no two
HAP create the same health risks and that reducing tons of one
pollutant does not produce the same benefit as reducing tons of
another. The commenter added that the EPA should not base its final
standards on cost effectiveness at all; the Agency's job is simply to
determine the ``maximum'' degree of reduction that can be achieved
considering cost, under CAA section 112(d)(2), and to assure an ``ample
margin of safety to protect public health'' under CAA section
112(f)(2). The commenter stressed that if the EPA wishes to consider
cost effectiveness in any meaningful sense, it cannot rely on the cost-
per-ton, which says nothing about the true effectiveness of reducing
emissions of highly toxic pollutants, in terms of public health--which
is a key factor missing from the EPA's analysis. Thus, the commenter
concluded it was arbitrary and capricious for the EPA to decide that it
was not necessary to update the standards to account for storage vessel
developments based on cost.
    The commenter also contended the EPA may consider cost but CAA
section 112(d)(6) does not authorize the EPA to refuse to update
standards based on cost. The commenter stated the Court has recognized
that developments are the core requirement, and if developments have
occurred, the EPA must account for those. The commenter further claimed
that the EPA should follow the plain text of CAA section 112(d)(2)-(3)
and applicable precedent requiring explicit authorization to consider
cost. The commenter stated the EPA's cost-focused analysis ignores the
statutory objective of assuring the ``maximum'' achievable degree of
emission reduction provided in CAA section 112(d)(2), as implemented
through the technology review. The commenter stated that this analysis
also ignores the statutory goal of protecting public health, per CAA
section 112 (f)(2).
    The commenter also stated that although the EPA initially
considered tightening the threshold for storage vessel capacity from 95
m\3\ to 38 m\3\, the EPA proposed a threshold of 59 m\3\ because it
found that ``it would not be cost-effective for this particular storage
vessel to add additional controls due to its infrequent use.'' The
commenter contended that the EPA cannot set a higher capacity threshold
simply based on the cost of installing a control on one affected
vessel, especially without information or analysis.
    Response: We disagree with the comment that the EPA has an
obligation to review prior MACT determinations and recalculate MACT
floors as part of each CAA section 112(d)(6) review given that this
argument has been repeatedly rejected by the Court. See, e.g., Nat'l
Ass'n of Surface Finishing v. EPA, 795 F.3d 1 (DC Cir. 2015);
Association of Battery Recyclers v. EPA, 716 F.3d 667, 673 (DC Cir.
2013); Natural Resources Defense Council (NRDC) v. EPA, 529 F.3d 1077
(DC Cir. 2008). In the proposal we neither re-evaluated nor re-opened
the MACT standard for storage vessels under CAA sections 112(d)(2) and
(3) in this action. For storage vessels, the revisions we proposed were
as a result of the RTR under CAA sections 112(d)(6) and (f)(2). As also
explained at proposal, under section 112(d)(6), the EPA is to review
the ``emission standards promulgated under'' CAA section 112(d)(2) and
(3). The EPA has consistently posited that CAA section 112(d)(6)
focuses on the review of developments that have occurred in a source
category since the original promulgation of a MACT standard. Similarly,
the EPA is to conduct a risk review that evaluates whether the emission
limits--the ``standards promulgated pursuant to subsection (d),'' [CAA
section 112(f)(2)(A)]--should be made more stringent to reduce the risk
posed after compliance with the underlying MACT standard. Therefore,
the EPA does not have an obligation in its technology and

residual risk review to consider ``hypothetical'' facilities that is,
facilities that have yet to begin construction (or may never even be
constructed or operate) and where air emissions from ethylene
production operations are merely anticipated because said operations do
not yet exist and facilities have yet to start up. As also previously
discussed we are not finalizing these proposed revisions under CAA
section 112(d)(6) because they are not cost effective. In addition, the
proposed revisions have little to no impact on HAP emissions for the
source category. With respect to the role of cost in our decisions
under the technology review, we note that the Court has not required
the EPA to demonstrate that a technology is ``cost-prohibitive'' in
order not to require adopting a new technology under CAA section
112(d)(6); a simple finding that a control is not cost effective is
enough. See Association of Battery Recyclers, et al. v. EPA, et al.,
716 F.3d 667, 673-74 (D.C. Cir. 2015) (approving the EPA's
consideration of cost as a factor in its CAA section 112(d)(6)
decision-making and the EPA's reliance on cost effectiveness as a
factor in its standard-setting).
    The commenter's comparison of cost-per-ton estimates against other
rules and other requirements within this final rule is also misplaced.
The commenter draws a comparison to an analysis for metal HAP in the
Secondary Lead NESHAP RTR, where those costs per ton were determined to
be within the range of metal HAP values for other CAA section 112 rules
(see 77 FR 576, January 5, 2012). However, organic HAP are the issue of
concern for storage vessels, and the EPA has historically used a
different and significantly lower cost-effectiveness scale for organic
HAP versus metal HAP due to their relative toxicity. Generally, for
organic HAP, we consider a cost effectiveness of $10,000/ton or more to
be near the upper end of what the EPA has traditionally considered to
be cost effective for control for these particular type of HAP.
    In addition, we disagree with the commenter that consideration of
incremental cost effectiveness was an unreasonable approach for
comparing differing strategies that build upon one another. We note
that CAA section 112(d)(6) does not prescribe a methodology for the
agency's costs analysis, and the EPA has sometimes presented cost/ton-
reduced numbers in the supporting analyses for regulations that we
issue. See for example, Husqvarna AB v. EPA, 254 F. 3d 195 at 200 (D.C.
Cir. 2001) (``Because section 213 does not mandate a specific method of
cost analysis, we find reasonable the EPA's choice to consider costs on
the per ton of emissions removed basis.''). For storage vessels, we
proposed to tighten the capacity and MTVP thresholds for control (known
as option SV1 in our technology review memorandum) and also evaluated
two other control options that built upon option SV1. Option SV1 was
evaluated in concert with the two other options, including adding
enhanced monitoring requirements (option SV2) and requiring EFR storage
vessels to convert to IFR storage vessels via use of geodesic domes
(option SV3). The costs are presented such that the overall HAP cost
effectiveness for options SV2 and SV3 also include option SV1, while
the incremental cost-effectiveness values for options SV2 and SV3 are
the cost-effectiveness values only for requiring enhanced monitoring
and only for requiring EFR storage vessels to convert to IFR storage
vessels via use of geodesic domes, respectively. Simply put, the
incremental cost-effectiveness values for options SV2 and SV3 do not
include costs and emissions reductions for option SV1. The commenter
did not provide additional details on costs or emissions reductions on
these options; thus, we continue to believe these options are not cost-
effective and are not finalizing them. An incremental cost-
effectiveness analysis was not needed for equipment leaks or waste
operations because we did not propose any revisions under our CAA
section 112(d)(6) technology review for these emission sources. We also
did not consider control options for these emission sources that would
build upon each other and necessitate an evaluation of incremental
costs and, thus, the HAP cost effectiveness for the options presented
in those analyses are equivalent to the incremental cost- effectiveness
values presented for options SV2 and SV3 for storage vessels. For
further information on our technology review for storage vessels, see
the technical memorandum, Clean Air Act Section 112(d)(6) Technology
Review for Storage Vessels Located in the Ethylene Production Source
Category, which is available in Docket ID Item No. EPA-HQ-OAR-2017-
0357-0014.
    Lastly, we disagree with the commenter that it was unreasonable to
consider an infrequently used storage vessel with a capacity of 58 m\3\
(i.e., a storage vessel with a capacity within the threshold of 38 m\3\
and 59 m\3\, which we evaluated, but did not propose) with little
emissions and an extremely high cost-effectiveness value for control in
setting the size threshold for control in our SV1 option evaluated
under our CAA section 112(d)(6) review. As explained in the technology
review memorandum, we first looked at other chemical sector and
refinery NESHAP for storage vessel control thresholds for capacity and
MTVP as a starting point and then we used our CAA section 114 ICR data
to further refine option SV1. Based on our CAA section 114 data, only
one storage vessel (with a capacity of 58 m\3\) met the most stringent
requirements for control from other NESHAP compared to the option we
evaluated and would be impacted were we to evaluate this storage vessel
in option SV1 (along with the other 12 storage vessels we anticipated
would also be affected at proposal). Using the information from our CAA
section 114 request that was submitted for this storage vessel (e.g.,
size, number of tank turnovers, stored material composition), we
conservatively estimated that this 58 m\3\ storage vessel would only
have annual emissions of 0.005 tpy of HAP if it had one full turnover
(even though it reported having none in 2013). Considering the extreme
case that all these emissions would be reduced from this storage vessel
if it were required to be controlled, and if we made several other
assumptions (e.g., retrofit with an IFR, 12-foot diameter tank, one of
each of the various upgraded deck fittings), we determined that
controlling this one storage vessel would have an annualized cost of
approximately $5,550 per year and not be cost effective (i.e., over
$1,000,000 per ton of HAP). We note that this information was available
in the docket for commenters to use and provide their own estimates of
HAP emissions and costs for control for this storage vessel. When
considering this information, we find the option to tighten the
capacity and MTVP thresholds to be even less cost effective if you
consider impacts requiring control from the 58 m\3\ storage vessel.
Thus, as previously discussed, we are not finalizing the proposed
capacity and MTVP thresholds we proposed for storage vessels and are
keeping the current MACT level of control for storage vessels in place.
    Comment: We received comments in support of and against the
proposal to require use of the Modified El Paso Method for repairing
leaks in heat exchange systems. A commenter that supported the proposal
noted that at least eight facilities in the source category were
already using the Modified El Paso Method. On the other hand, some
commenters said the EPA's proposed control requirements for heat

exchange systems were not cost effective when considering the actual
costs to repair leaks. A commenter said that the costs provided in
Table 7 of the memorandum, Clean Air Act Section 112(d)(6) Technology
Review for Heat Exchange Systems Located in the Ethylene Production
Source Category, significantly underestimates the true cost associated
with leak repair at ethylene production facilities. The commenter
contended that for purposes of leak repair, after identifying a leak,
maintenance and operations personnel must develop a strategy and
schedule to remove the leaking exchanger from service, which involves
identifying and selecting options for: Bypassing the process stream
from the leaking system, the amount of production turndown necessary
while the exchanger is out of service, identifying and selecting the
appropriate contract personnel, and scheduling the work so that it does
not conflict with any other planned maintenance. According to the
commenter, several different personnel would be involved in these
planning tasks including management, maintenance, production, and
engineering staff (128 hour estimate is based on 32 hours x 4 persons).
In addition to these planning costs, the commenter said that the EPA
did not include costs for bypassing the leaking system to avoid a total
shutdown which may include renting and plumbing temporary heat
exchangers. The commenter also said that the EPA did not include costs
for the rental and installation of cranes and scaffolding for accessing
the heat exchanger for repairs, and costs for specialized contracted
maintenance support to de-head the exchanger and perform the repair.
Based on maintenance records, the commenter contended that repair costs
range from $200,000 to $400,000 per event, not considering lost profit
due to turndown or shutdown of the production unit. Factoring in these
additional costs and using the EPA's estimated HAP emissions reductions
of 25 tpy, the commenter said the revised cost effectiveness becomes
$16,200 per ton of HAP. The commenter cited the RTR for Friction
Materials Manufacturing Facilities (83 FR 19511, May 3, 2018) where the
EPA found that $3,700 per ton for a permanent total enclosure was not
cost effective, and the RTR for the Petroleum Refinery Sector (79 FR
36916, June 30, 2014) where the EPA found that $14,100 per ton for
lowering leak definitions was not cost effective. The commenter also
said that in cases where the leaking heat exchanger must be completely
replaced to fix the leak, the costs exceed $1 million. The commenter
stated that the EPA acknowledged in the preamble that emissions from
heat exchange systems have an overall small contribution to cancer risk
to the individual most exposed and that additional controls for heat
exchange systems are not necessary to provide an ample margin of
safety.
    Response: We disagree with commenters that said the proposed
requirements for heat exchange systems to use the Modified El Paso
Method and a leak definition of 6.2 ppmv of total strippable
hydrocarbon concentration (as methane) in the stripping gas are not
cost-effective. We are finalizing this proposed development under CAA
section 112(d)(6) with some minor technical clarifications that are
discussed elsewhere in the rulemaking record (see our response in this
preamble to commenters' requests to include an alternative mass-based
leak definition; also see the document, Summary of Public Comments and
Responses for the Risk and Technology Review for Ethylene Production,
which is available in Docket ID No. EPA-HQ-OAR-2017-0357). We note that
the existing MACT standards that were finalized in 2002 (67 FR 46258,
July 12, 2002) contained LDAR provisions and many of the items
commenters include in their cost estimates are associated with repair
costs that would have already been incurred under the existing MACT
standards. These repair costs include, but are not limited to,
planning, bypassing, various equipment rental costs, costs for
scaffolding, and deheading. We also disagree with commenter's cost
estimates because most of the items that they claim are associated with
the proposed revision will not be required by this final rule
requirement (i.e., we determined that the costs associated with the
difference between conducting leak sampling using water sampling
methods and leak sampling using the Modified El Paso Method as well as
costs associated with combined operator and maintenance labor to find
and repair a leak by plugging are the only costs that would be
additionally incurred by the technology review standards). Further,
commenters failed to provide enough information demonstrating why their
costs information represents leak repair costs for an average heat
exchange system at an ethylene production facility. For example,
facilities may have additional heat exchange system capacity available
at their facility and may opt to use this capacity to repair the leak,
at no additional expense, yet this was not considered by commenters.
Also, commenters did not provide additional information for us to
evaluate the percentage of time additional leaks would have to be fixed
under the revised heat exchange system standards proposed under
technology review compared to the original MACT standards. Thus, we
continue to believe that the majority, if not all of the repair costs
cited by commenters would have been accounted for and incurred as a
result of the existing MACT standards and that simply plugging a
leaking heat exchanger would more likely represent the average cost
additionally incurred by ethylene production sources as a result of
this technology review development. In addition, in the proposed rule
we explained that we considered a heat exchanger to effectively be at
the end of its useful life if it was leaking to such an extent that it
would need to be replaced in order to comply with the requirement; so
the cost of replacing the heat exchanger would be an operational cost
that would be incurred by the facility as a result of routine
maintenance and equipment replacement and not attributable to the
proposed work practice standard that is being finalized in this action
(see the technical memorandum, Clean Air Act Section 112(d)(6)
Technology Review for Heat Exchange Systems in the Ethylene Production
Source Category, which is available in Docket ID No. EPA-HQ-OAR-2017-
0357). Thus, given all of this information, we continue to believe that
those costs associated with the difference between conducting leak
sampling using water sampling methods and leak sampling using the
Modified El Paso Method as well as costs associated with combined
operator and maintenance labor to find and repair a leak by plugging
are the only costs that would be additionally incurred by the
technology review standards. Based on our analysis, we find that the
revised standards we proposed for heat exchange systems are cost
effective at $1,060 per ton of HAP without consideration of product
recovery and result in a cost savings when you consider product
recovery. Therefore, we are finalizing the revisions for heat exchange
systems that we proposed under CAA section 112(d)(6) with some minor
technical clarifications that are discussed elsewhere in this preamble
and in the document, Summary of Public Comments and Responses for the
Risk and Technology Review for Ethylene Production, which is available
in Docket ID No. EPA-HQ-OAR-2017-0357.
    Additionally, with respect to rules where we have determined that

requirements are not cost effective at varying levels of cost
effectiveness, we note that there can be other compelling factors
beyond cost effectiveness that play a role in the EPA's determinations
and that each rulemaking is unique and should be judged on its own
merits. With respect to the two proposed rules commenters cited, we
note that different determinations likely would have resulted if some
of the other variables in those rulemaking records were not considered,
such as for the Friction Materials RTR (83 FR 19511, May 3, 2018) where
no facilities in the source category would have been impacted by rule
revisions under the technology review due to process changes and use of
non-HAP solvents. Similarly, for the Petroleum Refinery RTR (79 FR
36916, June 30, 2014), consideration of other fugitive emissions
management techniques that were finalized (e.g., fenceline monitoring)
also had the potential to help control equipment leaks in the Petroleum
Refinery source category. Regardless, and as stated above, we believe
that the developments we identified for heat exchange systems used in
the Ethylene Production source category are cost effective and are
finalizing these revisions under CAA section 112(d)(6).
    Comment: Some commenters recommended the EPA revise 40 CFR
63.1086(e)(i) through (iii) to include an alternative mass-based leak
definition. Commenters argued that by only defining a leak on a
concentration basis, smaller facilities with lower heat exchange system
recirculation rates would be forced to identify and fix leaks with a
much lower potential HAP emissions rate than facilities with larger
recirculation systems.
    A commenter said the EPA should calculate the equivalent mass-based
emission rate using the 90th percentile heat exchange system
recirculation rates (165,000 gpm) and the leak definition of 6.2 ppmv
as methane in the stripping gas, assuming 100 percent of the
hydrocarbon is hexane, for an equivalent mass leak-based leak
definition of 6.1 pounds per hour (2.8 kilograms per hour) of Table 1
to 40 CFR part 63, subpart XX HAP.
    Another commenter said the EPA should modify the leak action level
to be defined as potential strippable hydrocarbon emissions greater
than 4.0 pounds per hour for heat exchange systems with a recirculation
flowrate less than or equal to 100,000 gpm. The commenter asserted that
the memorandum, CAA Section 112(d)(6) Technology Review for Heat
Exchangers Located in the Ethylene Production Source Category, mentions
one case where the concentration of methane was 6.1 ppmv in the gas
phase and just less than 80 parts per billion by weight (ppbw) in the
water phase, thus, resulting in emissions of 0.64 pounds per hour based
on a recirculation rate of 17,000 gpm. Using this information, the
commenter determined that an average cooling water system with a
recirculation rate of 100,000 gpm (the average cooling water
recirculation rate of the ethylene production industry based on the
responses the EPA received to the CAA section 114 ICR) and a
concentration of strippable hydrocarbons in the water of 80 ppbw, will
have potential strippable hydrocarbon emissions of 4 pounds per hour.
    A commenter also recommended the EPA adjust the ``delay of repair''
leak action level in 40 CFR 63.1088(d)(3) to 40 pounds per hour of
potential strippable hydrocarbon emissions for heat exchange systems
with a recirculation rate of 100,000 gpm or less, and maintain the
``delay of repair'' action level at a total strippable hydrocarbon
concentration (as methane) in the stripping gas of 62 ppmv
(approximately 800 ppbw in the cooling water) for heat exchange systems
with a recirculation rate greater than 100,000 gpm.
    Response: We agree with commenters that an alternative mass-based
leak action level is warranted, and that by not finalizing such an
alternative, smaller heat exchange systems with low recirculation rates
would be disproportionally affected and forced to repair leaks with a
much lower potential HAP emissions rate than facilities with larger
recirculation rate systems. We disagree with commenters, however, that
the foundation of the alternative mass-based leak action level should
be based on the average recirculation rate in the source category of
100,000 gpm or the 90th percentile heat exchange system recirculation
rate of 165,000 gpm. As commenters allude to, the goal of this
alternative is to not disproportionally impact small heat exchange
systems with low emissions potential. To that end and given that this
is a technology review under CAA section 112(d)(6), consideration of
where it is cost-effective to repair a leaking heat exchange system
should be a primary consideration for this alternative. In our
technology review memorandum, Clean Air Act Section 112(d)(6)
Technology Review for Heat Exchange Systems Located in the Ethylene
Production Source Category, at Docket ID Item No. EPA-HQ-OAR-2017-0357-
0011, the nationwide impacts and emissions reductions presented in
Tables 15 and 16 are used to determine the HAP cost effectiveness for
the source category on average. In other words, the nationwide impacts
for HAP cost effectiveness (without consideration of product recovery)
at $1,060/ton of HAP would be the HAP cost effectiveness for an average
heat exchange system in the source category that has a recirculation
rate of approximately 100,000 gpm. We also generally consider that
technology review developments are not cost effective for organic HAP
if the cost effectiveness is more than $10,000/ton (or approximately 10
times higher than the cost effectiveness estimated for the average heat
exchange system at ethylene production sources). Since the
recirculation rate directly correlates to mass emissions potential at
the same leak concentration, the mass emissions for a heat exchange
system with recirculation rate of 10,000 gpm or less would be at least
10 times smaller compared to a 100,000 gpm recirculation rate system
and the annual costs to find and repair leaks would not change. As
such, we determined that it is not cost effective to control leaks at
the leak action level of total strippable hydrocarbon of 6.2 ppmv (as
methane) for heat exchange systems with a recirculation rate of 10,000
gpm or less, because the HAP cost effectiveness would be approximately
$10,000/ton of HAP or more. Therefore, to alleviate the concern about
disproportionally impacting small heat exchange systems with low HAP
emissions potential, and to ensure our technology review developments
are cost effective for all heat exchange systems in the source
category, we are finalizing an alternative total hydrocarbon mass-based
emissions rate leak action level (as methane) of 0.18 kilograms per
hour (0.4 pounds per hour) for heat exchange systems in the Ethylene
Production source category that have a recirculation rate of 10,000 gpm
or less. We also agree that for consistency, and to not
disproportionately impact small heat exchange systems, that an
alternative mass-based leak action level of 1.8 kilograms per hour (4.0
pounds per hour) for delay of repair for heat exchange systems with a
recirculation rate of 10,000 gpm or less is warranted.
4. What is the rationale for our final approach for the technology
review?
    Our technology review focused on the identification and evaluation
of developments in practices, processes, and control technologies that
have occurred since the EMACT standards were originally promulgated on
July 12, 2002 (67 FR 46258). Specifically, we

focused our technology review on all existing MACT standards for the
various emission sources in the Ethylene Production source category,
including, storage vessels, ethylene process vents, transfer racks,
equipment leaks, waste streams, and heat exchange systems. In the
proposal, we only identified cost-effective developments for storage
vessels and heat exchange systems and proposed to tighten the standards
for these two emissions sources under technology review. We did not
identify developments in practices, processes, or control technologies
for ethylene process vents, transfer racks, equipment leaks, and waste
streams. Further rationale about the technology review can be found in
the proposed rule (84 FR 54278, October 9, 2019) and in the supporting
materials in the rulemaking docket at Docket ID No. EPA-HQ-OAR-2017-
0357.
    During the public comment period, we received several comments on
our proposed determinations for the technology review. The comments and
our specific responses and rationale for our final decisions can be
found in section IV.B.3 of this preamble and in the document, Summary
of Public Comments and Responses for the Risk and Technology Reviews
for the Ethylene Production Source Category, available in the docket
for this action. No information presented by commenters has led us to
change our proposed determination, under CAA section 112(d)(6) for
ethylene process vents, transfer racks, equipment leaks, and waste
streams, and we are finalizing our determination that no changes to
these standards are warranted. Substantive information was submitted by
commenters on proposed revisions for heat exchange systems, and based
on this information, we are finalizing revisions for heat exchange
systems and making some technical clarifications to allow compliance
with an alternative mass-based leak action level for small heat
exchange systems with a recirculation rate of 10,000 gpm or less in
lieu of the concentration-based leak action level that was proposed.
Lastly, for storage vessels, substantive information was also submitted
by commenters, and based on this additional information, we find that
the developments we proposed are not cost effective for this emissions
source. Thus, we are not finalizing any changes for storage vessels as
a result of the technology review.

C. Amendments Pursuant to CAA Section 112(d)(2) and (d)(3) for the
Ethylene Production Source Category

1. What did we propose pursuant to CAA section 112(d)(2) and (3) for
the Ethylene Production source category?
    Under CAA section 112(d)(2) and (3) we proposed to amend the
operating and monitoring requirements for flares used as APCDs in the
Ethylene Production source category to ensure that facilities that use
flares as APCDs meet the EMACT standards at all times when controlling
HAP emissions. We proposed to add a provision, 40 CFR 63.1103(e)(4), to
extend the application of the Petroleum Refinery Flare Rule
requirements in 40 CFR part 63, subpart CC to flares in the Ethylene
Production source category with clarifications, including, but not
limited to, specifying that several definitions in 40 CFR part 63,
subpart CC, that apply to petroleum refinery flares also apply to
flares in the Ethylene Production source category, adding a definition
and requirements for pressure-assisted multi-point flares, and
specifying additional requirements when a gas chromatograph or mass
spectrometer is used for compositional analysis. Specifically, we
proposed to retain the General Provisions requirements of 40 CFR
63.11(b) and 40 CFR 60.18(b) that flares used as APCDs in the Ethylene
Production source category operate pilot flame systems continuously and
that flares operate with no visible emissions (except for periods not
to exceed a total of 5 minutes during any 2 consecutive hours) when the
flare vent gas flow rate is below the smokeless capacity of the flare.
We also proposed to consolidate measures related to flare tip velocity
and new operational and monitoring requirements related to the
combustion zone gas. Further, in keeping with the elimination of the
SSM exemption, we proposed a work practice standard related to the
visible emissions and velocity limits during periods when the flare is
operated above its smokeless capacity (e.g., periods of emergency
flaring). We proposed eliminating the cross-references to the General
Provisions and instead to specify all operational and monitoring
requirements that are intended to apply to flares used as APCDs in the
Ethylene Production source category.
    In addition, we proposed provisions and clarifications for periods
of SSM and bypasses, including PRD releases, bypass lines on closed
vent systems, in situ sampling systems, maintenance activities, and
certain gaseous streams routed to a fuel gas system to ensure that CAA
section 112 standards apply continuously, consistent with Sierra Club
v. EPA 551 F. 3d 1019 (D.C. Cir. 2008). For PRD releases, we proposed
at 40 CFR 63.1103(e)(2) definitions of ``pressure relief device'' and
``relief valve'' and proposed to add a work practice standard at 40 CFR
63.1107(h)(3), (6), and (7) for PRDs that vent to atmosphere that
requires three prevention measures and root cause analysis and
corrective action when a release occurs.\4\ We proposed to require that
sources monitor PRDs that vent to the atmosphere using a system that is
capable of identifying and recording the time and duration of each
pressure release and of notifying operators that a pressure release has
occurred. We also proposed to add a provision, 40 CFR 63.1107(h)(4), to
require PRDs that vent through a closed vent system to a control device
or to a process, fuel gas system, or drain system meet minimum
requirements for the applicable control system. In addition, we
proposed to add a provision, 40 CFR 63.1107(h)(5), to exclude the
following types of PRDs from the work practice standard for PRDs that
vent to the atmosphere: (1) PRDs with a design release pressure of less
than 2.5 pounds per square inch gauge (psig); (2) PRDs in heavy liquid
service; (3) PRDs that are designed solely to release due to liquid
thermal expansion; and (4) pilot-operated and balanced bellows PRDs if
the primary release valve associated with the PRD is vented through a
control system. Finally, we proposed to add a provision, 40 CFR
63.1107(h)(8), to require future installation and operation of non-
flowing pilot-operated PRDs at all affected sources.
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    \4\ Examples of prevention measures include flow indicators,
level indicators, temperature indicators, pressure indicators,
routine inspection and maintenance programs or operator training,
inherently safer designs or safety instrumentation systems, deluge
systems, and staged relief systems where the initial PRD discharges
to a control system.
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    For bypass lines on closed vent systems, we proposed to add a
provision, 40 CFR 63.1103(e)(6), to not allow an owner or operator to
bypass the APCD at any time, and if a bypass is used, then the owner or
operator is to estimate and report the quantity of organic HAP
released. We proposed this revision to be consistent with Sierra Club
v. EPA, 551 F.3d 1019 (D.C. Cir. 2008), where the Court determined that
standards under CAA section 112(d) must provide for compliance at all
times, because bypassing an APCD could result in a release of regulated
organic HAP to the atmosphere. We also proposed that the use of a cap,
blind flange, plug, or second valve on an

open-ended valve or line is sufficient to prevent a bypass. For in situ
sampling systems, we proposed to delete the exclusion of ``in situ
sampling systems (online analyzers)'' from the definition of ``ethylene
process vent'' and require that these kinds of vents meet the standards
applicable to ethylene process vents at all times.
    For maintenance activities, we proposed a definition for
``periodically discharged'' and removed ``episodic or nonroutine
releases'' from the list of vents not considered ethylene process
vents. We proposed to add a work practice standard at 40 CFR
63.1103(e)(5) requiring that, prior to opening process equipment to the
atmosphere, the equipment either: (1) Be drained and purged to a closed
system so that the hydrocarbon content is less than or equal to 10
percent of the lower explosive limit (LEL); (2) be opened and vented to
the atmosphere only if the 10-percent LEL cannot be demonstrated and
the pressure is less than or equal to 5 psig, provided there is no
active purging of the equipment to the atmosphere until the LEL
criterion is met; (3) be opened when there is less than 50 pounds of
VOC that may be emitted to the atmosphere; or (4) for installing or
removing an equipment blind, depressurize the equipment to 2 psig or
less and maintain pressure of the equipment where purge gas enters the
equipment at or below 2 psig during the blind flange installation,
provided none of the other proposed work practice standards can be met.
For cases where an emission source is required to be controlled in the
EMACT standards but is routed to a fuel gas system, we proposed to add
footnote b to Table 7 of 40 CFR 63.1103(e) to require that any flare,
utilizing fuel gas whereby the majority (i.e., 50 percent or more) of
the fuel gas in the fuel gas system is derived from an ethylene
production unit, comply with the proposed flare operating and
monitoring requirements.
    We proposed to add work practice standards at 40 CFR 63.1103(e)(7)
and (8) to address the decoking of ethylene cracking furnaces (i.e.,
the coke combustion activities in an ethylene cracking furnace), which
is defined as a shutdown activity and was previously only required to
minimize emissions by following a startup, shutdown, malfunction plan.
This ensures that CAA section 112 standards apply continuously. To
minimize coke combustion emissions from the decoking of the radiant
tube(s) in each ethylene cracking furnace, we proposed that an owner or
operator must conduct daily inspections of the firebox burners and
repair all burners that are impinging on the radiant tube(s) as soon as
practical, but not later than 1 calendar day after the flame
impingement is found. We also proposed that an owner or operator
conduct two of the following activities: (1) Continuously monitor (or
use a gas detection tube every hour to monitor) the CO2
concentration at the radiant tube(s) outlet for indication that the
coke combustion in the ethylene cracking furnace radiant tube(s) is
complete; (2) continuously monitor the temperature at the radiant
tube(s) outlet to ensure the coke combustion occurring inside the
radiant tube(s) is not so aggressive (i.e., too hot) that it damages
either the radiant tube(s) or ethylene cracking furnace isolation
valve(s); (3) after decoking, but before returning the ethylene
cracking furnace back to normal operations, purge the radiant tube(s)
with steam and verify that all air is removed; or (4) after decoking,
but before returning the ethylene cracking furnace back to normal
operations, apply a coating material to the interior of the radiant
tube(s) to protect against coke formation inside the radiant tube
during normal operation. In addition, we proposed that the owner or
operator must conduct the following inspections for ethylene cracking
furnace isolation valve(s): (1) Prior to decoking operation, inspect
the applicable ethylene cracking furnace isolation valve(s) to confirm
that the radiant tube(s) being decoked is completely isolated from the
ethylene production process so that no emissions generated from
decoking operations are sent to the ethylene production process; and
(2) prior to returning the ethylene cracking furnace to normal
operations after a decoking operation, inspect the applicable ethylene
cracking furnace isolation valve(s) to confirm that the radiant tube(s)
that was decoked is completely isolated from the decoking pot or
furnace firebox such that no emissions are sent from the radiant
tube(s) to the decoking pot or furnace firebox once the ethylene
cracking furnace returns to normal operation.
    More information concerning our proposal to address CAA section
112(d)(2) and (3) can be found in the proposed rule (84 FR 54278,
October 9, 2019).
2. How did the revisions pursuant to CAA section 112(d)(2) and (3)
change since proposal?
    The EPA is finalizing the revisions to the monitoring and
operational requirements for flares, as proposed, except that we are
not finalizing the work practice standard for velocity exceedances for
flares operating above their smokeless capacity. In response to
comments that owners or operators have historically considered
degassing emissions from shutdown of storage vessels to be covered by
their SSM plans per 40 CFR 63.1108(a)(5) and relied on the language in
40 CFR 63.1108(a)(5) that back-up control devices are not required, we
are adding a separate standard for storage vessel degassing for storage
vessels subject to the control requirements in Table 7 to 40 CFR
63.1103(e)(3)(b) and (c). The standard requires owners or operators to
control degassing emissions for floating roof and fixed roof storage
vessels until the vapor space concentration is less than 10 percent of
the LEL. Storage vessels may be vented to the atmosphere once the
storage vessel degassing concentration threshold is met (i.e., 10
percent LEL) and all standing liquid has been removed from the vessel
to the extent practical.
    Lastly, based on comments received on the proposal, we are making
some minor editorial corrections and technical clarifications to the
work practice standards for the decoking of ethylene cracking furnaces.
Specifically, we are adding delay of repair provisions to the flame
impingement inspection requirements, adding clarifying text to the
CO2 monitoring, coil outlet temperature monitoring, air
removal, and radiant tube(s) treatment requirements, and removing
unnecessary recordkeeping associated with the time each isolation valve
inspection is performed and the results of that inspection even if poor
isolation was not found. For details about these minor changes, refer
to Section 6.7 of the document, Summary of Public Comments and
Responses for the Risk and Technology Reviews for the Ethylene
Production Source Category, available in the docket for this action.
3. What key comments did we receive on the proposal revisions pursuant
to CAA section 112(d)(2) and (3), and what are our responses?
    This section provides comment and responses for the key comments
received regarding our proposed revisions for flares and clarifications
for periods of SSM, including PRD releases, decoking operations for
ethylene cracking furnaces (i.e., the decoking of ethylene cracking
furnace radiant tubes), and storage vessel emptying and degassing.
Other comment summaries and the EPA's responses for additional issues
raised regarding these activities as well as issues raised regarding
our proposed revisions for bypass lines on closed vent systems, in situ
sampling systems, maintenance activities, and certain gaseous streams
routed to a fuel gas system, can be found in the

document, Summary of Public Comments and Responses for the Risk and
Technology Reviews for the Ethylene Production Source Category,
available in the docket for this action.
    Comment: We received comments in support of and against our
proposal to establish similar requirements for flares used in the
Ethylene Production source category as the flare requirements
established in the 2015 Petroleum Refinery NESHAP, including the
incorporation of the net heating value of the combustion zone (NHVcz)
calculation and limits. One commenter supported the proposed
strengthened operational and monitoring requirements, which the
commenter stated reflect best practices already in place at many
facilities and must be required pursuant to CAA sections 112(d)(2),
(3), and (6). The commenter reiterated the EPA's determination that
measuring the net heating value of the flare gas, as it enters the
flares, is insufficient to determine combustibility because facilities
add steam and other gases not accounted for and that flare performance
data shows that the net heating value of vent gas in the combustion
zone must reach at least 270 British thermal units per standard cubic
foot (Btu/scf). Some commenters also supported the EPA's proposal
``that owners or operators may use a corrected heat content of 1,212
Btu/scf for hydrogen, instead of 274 Btu/scf, to demonstrate compliance
with the NHVcz operating limit,'' because the data show that the
control efficiency of a flare drops off significantly below this level.
    Another commenter also suggested other improvements to the proposed
flared revisions. According to this commenter, data shows the proposed
rule does not assure heating values in the combustion zone that are
high enough to achieve the EMACT standards. The commenter said that the
EPA has an extensive record to support its conclusion that some
ethylene production facility flares do not destroy at least 98 percent
of HAP, and urged the EPA to mandate additional measures to ensure 98-
percent flare destruction efficiency. The commenter noted that at least
one operator, Formosa, recognizes that flares can achieve 99-percent
reduction in HAP emissions for small molecules.\5\ The commenter stated
that continuous monitoring of either the net heating value or
composition of flare gas must be required pursuant to CAA sections
112(d)(2), (3), and (6). The commenter recommended that the EPA also
consider the following measures to help assure compliance with 98-
percent destruction efficiency:
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    \5\ The commenter provided the following reference: RISE St.
James et al. Comments on 14 Proposed Initial Title V/Part 70 Air
Permits, Proposed Initial Prevention of Significant Deterioration
Permit, and the Associated Environmental Assessment Statement for FG
LA, LLC (Formosa) Chemical Complex, Attachment E at 18 (August 12,
2019).
---------------------------------------------------------------------------

     Prohibit wake dominated flow flaring conditions. The
commenter noted that studies have shown that high winds can decrease
flare destruction efficiency.\6\
---------------------------------------------------------------------------

    \6\ The commenter provided the following reference: Robert E.
Levy et al., Indus. Prof. for Clean Air, Reducing Emissions from
Plant Flares (No. 61) at 1 (April 24, 2006).
---------------------------------------------------------------------------

     Require continuous video monitoring and recording for
flares equipped with video monitoring and flares that vent more than 1
million standard cubic feet scf per day (MMscf/day).\7\
---------------------------------------------------------------------------

    \7\ The commenter provided the following reference: See 84 FR
54296; BAAQMD Sec.  12-11-507: requiring continuous video monitoring
and recording for flares equipped with video monitoring and flares
with vent gas more than 1 MMscf/day); SCAQMD Rule 1118(g)(7):
requiring continuous video monitoring and recording; Consent Decree,
United States of America v. Marathon Petroleum Company LP et al.,
No. 12-cv-11544 (E.D. Mich.) (April 5, 2012); Consent Decree, United
States of America et al. v. BP Products North America Inc., No. 12-
cv-0207 (N.D. Ind.) (May 23, 2012); Consent Decree, United States of
America v. Shell Oil Company et al., No. 13-cv-2009 (S.D. Tex.)
(July 10, 2013); Consent Decree, United States of America v. Flint
Hills Resources Port Arthur, LLC, No. 14-cv-0169, at 12 (E.D. Tex.)
(March 20, 2014).
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     Require monitoring of pilot gas, which is already required
by the South Coast Air Quality Management District (SCAQMD) and Bay
Area Air Quality Management District (BAAQMD).
    The commenter also stated that the EPA should require that
facilities conduct necessary flare maintenance and upgrades and have
additional flare capacity on standby. The commenter stated that if a
flare is smoking, that may mean it simply needs to be either maintained
or updated to address the problem. The commenter recommended add-on
equipment to augment the smokeless capacity of a flare.\8\ The
commenter also said that the EPA neither explained why other types of
conveyances are not possible, nor can the EPA justify a standard that
exempts equipment routed to a flare from the standards that generally
apply to such equipment.
---------------------------------------------------------------------------

    \8\ The commenter provided the following reference: John Zink
Hamworthy, Smokeless, Safe, Economical Solutions: Refining &
Petrochemical Flares. Pg. 4 (this technology can increase the
smokeless capacity of a flare by nearly 38 percent), available at
http://www.johnzink.com/wp-content/uploads/Flares-Refining-Petrochemical.pdf.
---------------------------------------------------------------------------

    Response: We appreciate the support from several commenters for the
flare operational and monitoring requirements being finalized at 40 CFR
63.1103(e)(4). However, we disagree with one commenter's request to
mandate additional measures to ensure 98-percent flare combustion
efficiency. The flare requirements we are finalizing are already
designed to ensure flares meet a minimum destruction efficiency of 98
percent, consistent with the MACT control requirements.
    We disagree with the commenter's specific request to prohibit wake
dominated flow flaring conditions as we have extremely limited data to
suggest that wind adversely impacts the combustion efficiency of
flares, let alone the combustion efficiency of industrial-sized flares
used at ethylene production units. Commenters submitted no new data to
otherwise support the assertion that wind does indeed affect flare
performance, and, as such, we are not persuaded into changing our
position at proposal that no flare operating parameter(s) are needed to
minimize wind effects on flare performance.
    We disagree with the commenter's specific request to require
continuous video monitoring and recording for flares equipped with
video monitoring and flares that vent more than 1 MMscf/day. We note
that in the final rule we have provided for the use of video camera
surveillance monitoring as an alternative to EPA Method 22 monitoring.
Observation via the video camera feed can be conducted readily
throughout the day and will allow the operators of the flare to watch
for visible emissions at the same time they are adjusting the flare
operations.
    We also disagree with the commenter's specific request to require
monitoring of pilot gas. The data available to us suggests that heat
release from the flare pilots are generally negligible when regulated
materials are sent to the flare and exclusion of the flare pilot gas
simplifies the NHVcz calculation. Even when only purge gas is used, the
flare pilots typically only provided about 10 percent of the total heat
input to the flare and typically well less than 1 percent in the recent
passive fourier transform infrared spectrometry flare tests when
potential regulated material is routed to the flare (this is dependent
on the size of the flare, number of pilots, and flare tip design, which
impacts minimum purge flows). We are finalizing the definition of flare
vent gas as proposed, which excludes pilot gas.
    Also, we disagree with the commenter's specific request to require
additional flare capacity on standby to avoid a smoking flare because
it would require new additional flares to operate at idle conditions
for the vast majority

of time, contributing to additional criteria pollutant emissions on a
continuous basis, while having only a small impact on HAP emissions.
For example, an existing flare burns approximately 25,000 to 100,000
standard cubic feet per day of natural gas (or fuel gas). If three new
flares are added for each existing flare to ensure flares do not smoke
during emergency shutdowns or other similar major events, then the
additional emissions per existing flare would be 1,000 to 4,100
megagrams per year of CO2 equivalence and 0.9 to 3.6 tpy of
nitrogen oxides. This estimate does not include emissions from the
generation of the extra steam needed for these flares to operate in a
smokeless manner during the emission events. Therefore, the secondary
impacts associated with having greater smokeless flare capacity would
be significant. In addition, it is not clear whether the specific
technology that the commenter cited to augment the smokeless capacity
of a flare (i.e., a specific steam-assisted flare system that uses
multiple-port supersonic nozzle technology) is an ``add-on''
technology, nor did the commenter provide any data to quantify or
substantiate the claims, or any other additional details on costs or
emissions reductions for it.
    Finally, the commenter did not provide any context regarding their
comment about other types of conveyances and justifying standards;
therefore, we are unable to respond to this portion of the comment.
    Comment: A commenter stated that the EPA improperly based the
proposed flare revisions on CAA sections 112(d)(2) and (3) and should
have evaluated them under CAA section 112(d)(6). The commenter stated
that in setting the original MACT, the EPA did not have actual data
demonstrating that the best performers were achieving 98-percent HAP
reduction with flares (and other combustion devices), but rather based
its conclusions on what it presumed sources would achieve if a
combustion device were operated consistent with the requirements in the
rule. The commenter further stated that the EPA is now claiming that
98-percent HAP reduction was not achieved in practice by the best
performers, and instead can only be achieved by the best performers if
they take additional steps to reduce emissions (e.g., meet NHVcz
requirements and implement additional monitoring). The commenter
contended the proposed flare revisions can only be either a BTF
standard or a revision as a result of the technology review, and the
EPA cannot make the standard more stringent simply by claiming it is
ensuring compliance with the current standard.
    The commenter argued the EPA should have evaluated the flare
revisions under CAA section 112 (d)(6), found the revisions were not
cost effective, and not proposed the flare revisions. To support the
commenter's contention that the proposed flare requirements would not
be cost effective, the commenter provided updated estimates for the
costs presented in Tables 3, 6, and 7 of the EPA memorandum, Control
Option Impacts for Flares Located in the Ethylene Production Source
Category. The commenter made the following statements regarding costs:
     The EPA did not consider the cost of constructing new
flares at existing facilities to meet the proposed requirements. The
commenter stated that they know that at least one company would be
required under the proposed rule to install at least two new flares,
due to the high potential for existing flares to exceed the number of
visible emissions events allowed, with a capital cost of $20 million
and annualized costs of $3.1 million.
     Gas chromatographs would need to be installed in certain
instances to comply with the proposed monitoring requirements, which
the commenter suggests would have an estimated nationwide capital
investment of $964,000 and annualized costs of $140,000 for
installation and operation.
     The EPA did not account for the costs associated with
upgrading natural gas controls and flow monitoring; the commenter
estimated approximately 47 flares will require upgraded supplemental
fuel controls and monitoring equating to a nationwide capital
investment of $5.3 million and an annualized cost of approximately $1
million.
     The EPA did not account for supplemental natural gas
firing to meet the revised NHVcz operating parameter, which the
commenter estimates would cost approximately $66.8 million per year in
additional operating costs.
     The EPA underestimated the costs to develop the flare
management plan by inappropriately relying on the cost estimated for
refineries. However, most refineries were subject to similar flare
management plan requirements under 40 CFR part 60, subpart Ja, and,
therefore, were only required to update existing plans, whereas the
commenter said ethylene producers will generally be required to develop
new flare management plans. The commenter estimated the cost to develop
a new flare management plan is $23,300 per flare.
     The EPA did not include the cost to develop the continuous
parametric monitoring system monitoring plan required by 40 CFR
63.671(b), which they estimate is an additional $7,400 per flare to
develop.
    Using their updated costs and the EPA's estimated 1,430 tpy of HAP
reductions, the commenter stated that the cost effectiveness of the
proposed flare requirements would be $55,874 per ton of HAP reduced.
The commenter argued that the EPA would have found the proposed flare
revisions not cost effective under CAA section 112(d)(6) and,
therefore, would not have included the changes in the proposed rule.
    Another commenter stated there would be complications complying
with the proposed flare revisions, which would further increase the
cost of the proposal, including: (1) When gas chromatographs are
currently in use, some flares will need to add calorimeters to directly
measure the net heating value on a minute-by-minute basis to help with
process control and meet the requirements on a 15-minute basis; (2)
some flares have multiple vent gas lines entering the flare system
(e.g., a line to the base of the flare and a line entering the side of
the flare stack) and additional vent gas monitors will be needed; (3)
some flares have two or more steam lines to the flare tip and