Proposed Rule2024-08004
Petition To Remove the Stationary Combustion Turbines Source Category From the List of Categories of Major Sources of Hazardous Air Pollutants
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
April 16, 2024
Issuing agencies
Environmental Protection Agency
Abstract
The U.S Environmental Protection Agency (EPA) is announcing the Agency's decision to deny a petition requesting the removal of the Stationary Combustion Turbines source category from the list of categories of major sources of hazardous air pollutants (HAP) subject to regulation the Clean Air Act (CAA). The petition was submitted jointly by American Fuel & Petrochemical Manufacturers, the American Petroleum Institute, the American Public Power Association, the Gas Turbine Association, the Interstate Natural Gas Association of America, and the National Rural Electric Cooperative Association ("the petitioners"). The EPA is denying the petition based on the EPA's determination that the petition is incomplete and because we have found that the submitted information is inadequate to determine that no source in the category emits HAP in quantities that may cause a lifetime risk of cancer greater than 1-in-1 million to the individual in the population who is most exposed to emissions of such pollutants from the source. We have reached this decision based on review of the risk analysis and other information submitted by petitioners and on consideration of turbine testing results received from a CAA information request. The EPA is denying the petition with prejudice and will deny any future petition to delist as a matter of law unless such future petition is accompanied by substantial new information or analysis.
Full Text
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<title>Federal Register, Volume 89 Issue 74 (Tuesday, April 16, 2024)</title>
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[Federal Register Volume 89, Number 74 (Tuesday, April 16, 2024)]
[Proposed Rules]
[Pages 26835-26846]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2024-08004]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 63
[EPA-HQ-OAR-2020-0408; FRL-7821-02-OAR]
RIN 2060-AU78
Petition To Remove the Stationary Combustion Turbines Source
Category From the List of Categories of Major Sources of Hazardous Air
Pollutants
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notification of denial of petition to delist.
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SUMMARY: The U.S Environmental Protection Agency (EPA) is announcing
the Agency's decision to deny a petition requesting the removal of the
Stationary Combustion Turbines source category from the list of
categories of major sources of hazardous air pollutants (HAP) subject
to regulation the Clean Air Act (CAA). The petition was submitted
jointly by American Fuel & Petrochemical Manufacturers, the American
Petroleum Institute, the American Public Power Association, the Gas
Turbine Association, the Interstate Natural Gas Association of America,
and the National Rural Electric Cooperative Association (``the
petitioners''). The EPA is denying the petition based on the EPA's
determination that the petition is incomplete and because we have found
that the submitted information is inadequate to determine that no
source in the category emits HAP in quantities that may cause a
lifetime risk of cancer greater than 1-in-1 million to the individual
in the population who is most exposed to emissions of such pollutants
from the source. We have reached this decision based on review of the
risk analysis and other information submitted by petitioners and on
consideration of turbine testing results received from a CAA
information request. The EPA is denying the petition with prejudice and
will deny any future petition to delist as a matter of law unless such
future petition is accompanied by substantial new information or
analysis.
DATES: Petitions for judicial review of this action must be filed June
17, 2024. See SUPPLEMENTARY INFORMATION for filing information.
ADDRESSES: In addition to being available in the docket, an electronic
copy of this action is available on the internet. Following signature,
the EPA will post a copy of this action at <a href="https://www.epa.gov/stationary-sources-air-pollution/stationary-combustion-turbines-national-emission-standards">https://www.epa.gov/stationary-sources-air-pollution/stationary-combustion-turbines-national-emission-standards</a>. Following publication in the Federal
Register, the EPA will post the Federal Register version of this action
at this same website.
FOR FURTHER INFORMATION CONTACT: For questions about this action
contact Ms. Angela M. Ortega, Sector Policies and Programs Division
(D243-01), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, P.O. Box 12055, Research Triangle
Park, North Carolina 27711; telephone number: (919) 541-4197; and email
address: <a href="/cdn-cgi/l/email-protection#e6899492838187c8878881838a87a6839687c8818990"><span class="__cf_email__" data-cfemail="751a07011012145b141b12101914351005145b121a03">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Docket. The EPA has established a docket for this rulemaking under
Docket ID No. EPA-HQ-OAR-2020-0408.\1\ All documents in the docket are
listed in <a href="https://www.regulations.gov">https://www.regulations.gov</a>. Although listed, some
information is not publicly available, e.g., Confidential Business
Information (CBI) or other information whose disclosure is restricted
by statute. Certain other material, such as copyrighted material, is
not placed on the internet and will be publicly available only in hard
copy. With the exception of such material, publicly available docket
materials are available electronically in <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
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\1\ As explained in a memorandum to the docket, the docket for
this action includes the documents and information in Docket ID Nos.
EPA-HQ-OAR-2017-0688 (Stationary Combustion Turbines NESHAP Risk and
Technology Review), EPA-HQ-OAR-2003-0196 (Proposal to stay the
enforcement of the combustion turbines National Emission Standards
Hazardous Air Pollutants for new sources in the lean premix gas-
fired turbines and diffusion flame gas-fired turbines
subcategories), EPA-HQ-OAR-2003-0189 (Proposal to delist four
subcategories from the Stationary Combustion Turbines source
category), and EPA-HQ-OAR-2002-0060 (National Emission Standards for
Hazardous Air Pollutants for Stationary Combustion Turbines).
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Judicial review. Section 307(b)(1) of the CAA governs judicial
review of final actions by the EPA. This section provides, in part,
that petitions for review must be filed in the United States Court of
Appeals for the District of Columbia Circuit: (i) when the Agency
action consists of ``nationally applicable regulations promulgated, or
final actions taken, by the Administrator,'' or (ii) when such action
is locally or regionally applicable, but ``such action is based on a
determination of nationwide scope or effect and if in taking such
action the Administrator finds and publishes that such action is based
on such a determination.'' For locally or regionally applicable final
actions, the CAA reserves to the EPA complete discretion to decide
whether to invoke the exception in (ii).\2\
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\2\ Sierra Club v. EPA, 47 F.4th 738, 745 (D.C. Cir. 2022)
(``EPA's decision whether to make and publish a finding of
nationwide scope or effect is committed to the agency's discretion
and thus is unreviewable''); Texas v. EPA, 983 F.3d 826, 834-35 (5th
Cir. 2020).
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This final action is ``nationally applicable'' within the meaning
of CAA section 307(b)(1). In this final action, the Administrator is
denying a petition to delist the entire Stationary Combustion Turbines
source category under CAA section 112(c)(9)(B). This action results in
the continued applicability of the National Emission Standards for
Hazardous Air Pollutants (NESHAP) for Stationary Combustion Turbines to
all turbines meeting the rule's applicability criteria located in any
state in the nation. For these reasons, this final action is nationally
applicable.
Under section 307(b)(1) of the CAA, petitions for judicial review
of this action must be filed in the United States Court of Appeals for
the District of Columbia Circuit within 60 days from April 16, 2024.
Filing a petition for reconsideration of this final action by the
Administrator does not affect the finality of this action for the
purposes of judicial review, nor does it extend the time within which a
petition for judicial review must be filed and shall not postpone the
effectiveness of such rule or action.
Under CAA section 307(b)(2) (42 U.S.C. 7607(b)(2)), the
requirements established by this final action may not be challenged
separately in any civil or criminal proceedings brought by the EPA to
enforce the requirements.
[[Page 26836]]
Organization of this document. The information in this preamble is
organized as follows:
I. General Information
A. What action is the EPA taking?
B. Background Information
II. Treatment of Petitions To Delist a Source Category From
Regulation Under CAA Section 112
A. What is a source category delisting petition and what are the
criteria for delisting a source category?
B. What is the process for delisting a source category?
III. Risk Review Methodology and Findings
A. The EPA's Risk Assessment Methodology
B. The EPA's 2020 Risk Review Findings
C. CAA Section 114 Information Request
IV. Evaluation of the Petition
A. Description of the Petition
B. Petitioners' Risk Assessment Methodology
C. Basis for Emission Estimates
D. HAP and Turbines Not Included in Petition
V. What is the rationale for denying the petition?
I. General Information
The EPA has received, has reviewed, and is now denying a petition
that requests the removal of a source category from the list of major
source categories of HAP, under CAA section 112. In section I.A., we
summarize the action we are taking today. In section I.B., we provide
information about the NESHAP program set forth in CAA section 112 and
the regulatory history and information for the source category at
issue. In section II., we discuss the delisting criteria outlined in
the CAA and the Agency's process for delisting a source category.
Section III. discusses the EPA's residual risk review methodologies and
findings in the 2020 Stationary Combustion Turbines NESHAP Risk and
Technology Review (2020 RTR) as well as the CAA section 114 information
request that the EPA issued subsequent to the 2020 RTR. Section IV.
presents the details of the petition to delist and the Agency's
technical evaluation of the petition. Finally, in section V., we
discuss the EPA's response to the petition.
A. What action is the EPA taking?
This action presents the Agency's decision to deny a petition
requesting the removal of the Stationary Combustion Turbines source
category from the list of categories of major sources of HAP subject to
regulation under CAA section 112. The petition was submitted jointly by
American Fuel & Petrochemical Manufacturers, the American Petroleum
Institute, the American Public Power Association, the Gas Turbine
Association, the Interstate Natural Gas Association of America, and the
National Rural Electric Cooperative Association (``the petitioners'').
The EPA's decision is governed by CAA section 112(c)(9), which
provides the EPA's discretionary authority to delist source categories
and specifies the health risk criteria that must be met for a source
category to be delisted. These criteria require the EPA to determine
that no source in the category emits HAP in quantities which may cause
a lifetime risk of cancer greater than 1-in-1 million to the individual
in the population who is most exposed to emissions of such pollutants
from the source and that HAP emissions from such source category would
not result in adverse effects to human health or the environment before
delisting a source category.
The EPA is denying the petition based on the EPA's determination
that the petition is incomplete and because the petitioners did not
present adequate information and analyses for each of the necessary
subject areas, under CAA section 112(c)(9)(B). After receipt of the
initial petition and the first supplement, the EPA requested that the
petitioners provide information and data to support the stationary
combustion turbine emission estimates provided by the petitioners; the
requested information was not provided. As an additional and separate
independent basis for the denial of the petition, the EPA has
determined that the petitioners' requested conclusions are not
supported by the evidence. The EPA is denying the petition with
prejudice and will deny any future petition to delist as a matter of
law unless such future petition is accompanied by substantial new
information or analysis.
B. Background Information
In this section, the EPA provides a brief overview of HAP
regulation under CAA section 112, the regulatory history of the
Stationary Combustion Turbines source category, information about the
source category and its HAP emissions, and information about delisting
petitions concerning this source category.
1. HAP Regulation Under CAA Section 112
CAA section 112 establishes the framework for regulation of HAP.
CAA section 112(c)(1) requires the EPA to publish a list of both
categories and subcategories of major and area sources of HAP. A source
category on the list is required to meet the specifically defined
emission standards that depend on the HAP emitted and whether a source
is a major source or an area source. Major sources of HAP are those
stationary sources or group of stationary sources under common control
(e.g., facilities) that emit or that have the potential to emit 10 tons
per year or more of any specific HAP or 25 tons per year or more of any
combination of HAP. An area source is any source of HAP that is not a
major source. CAA section 112(c)(2) further requires the EPA to
promulgate standards under CAA section 112(d) for all listed source
categories according to the schedule specified in CAA section 112(e).
CAA section 112(d)(6) requires the EPA to review these standards and
revise them as necessary, with consideration of developments in
practices, processes, and control technologies, every 8 years (the
``technology review''), and CAA section 112(f)(2) requires the EPA to
assess 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. When the two reviews
are combined into a single rulemaking, it is commonly referred to as
the ``risk and technology review'' (RTR).
2. Regulatory History of and Information About the Stationary
Combustion Turbines Source Category
On July 16, 1992, the EPA published the initial list of source
categories, which included the Stationary Turbines source category (57
FR 31576). This source category was subsequently renamed the Stationary
Combustion Turbines source category (64 FR 63025; November 18, 1999).
CAA section 112(c)(2) further requires the EPA to promulgate standards
under CAA section 112(d) for all listed source categories according to
the schedule specified in CAA section 112(e). The EPA promulgated the
NESHAP for Stationary Combustion Turbines on March 5, 2004 (69 FR
10512). The standards are codified at 40 CFR part 63, subpart YYYY and
apply to stationary combustion turbines at major sources of HAP. There
are no requirements under 40 CFR part 63, subpart YYYY for stationary
combustion turbines located at area sources. The RTR for the Stationary
Combustion Turbines NESHAP was proposed on April 12, 2019 (84 FR 15046)
and finalized on March 9, 2020 (85 FR 13524).\3\
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\3\ The EPA readopted the existing standards under CAA section
112(f)(2) (85 FR 13530).
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The Stationary Combustion Turbines source category covered by the
NESHAP
[[Page 26837]]
includes approximately 1,015 turbines at 310 facilities.\4\ Within the
Stationary Combustion Turbines source category are the following eight
subcategories: lean premix gas-fired turbines, lean premix oil-fired
turbines, diffusion flame gas-fired turbines, diffusion flame oil-fired
turbines, turbines which burn landfill or digester gas or gasified
municipal solid waste, turbines of less than 1 megawatt (MW) rated peak
power output, emergency turbines, and turbines operated on the North
Slope of Alaska. Stationary combustion turbines are typically located
at power plants, compressor stations, landfills, and industrial
facilities such as chemical plants. These turbines are generally
operated using natural gas, distillate oil, landfill gas, jet fuel, or
process gas.
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\4\ Turbine NESHAP Unit List--Updated October 2023. Docket ID
No. EPA-HQ-OAR-2020-0408.
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Emissions of HAP in the exhaust gases of turbines are the result of
combustion of the gaseous and liquid fuels. The HAP present in these
exhaust gases include formaldehyde, toluene, benzene, acetaldehyde, and
metallic HAP (e.g., cadmium, chromium, manganese, lead, and nickel). Of
these HAP, benzene, nickel subsulfide, and hexavalent chromium are
classified as known human carcinogens, and formaldehyde, acetaldehyde,
lead, nickel carbonyl, and cadmium are classified as probable human
carcinogens. Exposure to the various HAP emitted by stationary
combustion turbines is associated with a variety of adverse health
effects. These adverse health effects include chronic (long-term)
health disorders (e.g., effects on the central nervous system, damage
to the kidneys, and irritation of the lung, skin, and mucus membranes);
and acute health disorders (e.g., effects on the kidney and central
nervous system, alimentary effects such as nausea and vomiting, and
lung irritation and congestion).
Mercury has been measured in the exhaust gas from landfill gas-
fired turbines. Gaseous mercury emitted into the air eventually can be
deposited into soil and water bodies, where microorganisms can convert
it into methylmercury, a highly toxic form of mercury that bio-
accumulates in fish tissue and in other aquatic creatures. People are
primarily exposed to mercury by consuming contaminated fish.
Methylmercury exposure is a particular concern for people of
childbearing age, developing fetuses, and young children, because
studies have linked exposure to high levels of methylmercury to damage
to the developing nervous system. Children exposed to methylmercury
while they are in the womb can have negative impacts to their cognitive
thinking, memory, attention, language, fine motor skills, and visual
spatial skills. Animals can absorb mercury through water, air, and soil
or from eating certain plants. Mercury can harm an animal's ability to
reproduce and to care for their young.
3. Delisting Petitions Concerning the Stationary Combustion Turbines
Source Category
During the 2004 Stationary Combustion Turbines NESHAP rulemaking,
the EPA received a petition from the Gas Turbine Association to delist
two subcategories of stationary combustion turbines under CAA section
112(c)(9).\5\ The petitioners requested the EPA to create and delist
two subcategories--lean premix turbines firing natural gas with limited
oil backup and a low-risk subcategory where facilities would make site-
specific demonstrations regarding risk levels. On April 7, 2004, the
EPA proposed to delist the following four subcategories: lean premix
gas-fired turbines, diffusion flame gas-fired turbines, emergency
turbines, and turbines located on the North Slope of Alaska (69 FR
18327). At the same time, the EPA proposed to stay the effectiveness of
the NESHAP for new lean premix gas-fired and diffusion flame gas-fired
turbines (69 FR 18338). On August 18, 2004, the EPA finalized the
administrative stay of the effectiveness of the NESHAP for new lean
premix gas-fired and diffusion flame gas-fired turbines, pending the
outcome of the proposed subcategory delisting (69 FR 51184). The
proposal to delist the four subcategories was never finalized in light
of the 2007 decision in Natural Resources Defense Council v. EPA, 489
F.3d 1364 (D.C. Cir. 2007), which addressed limits on the EPA's ability
to delist subcategories. This court decision is discussed in more
detail in section II.A.
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\5\ Petition to Delist Two Subcategories of Combustion Turbines.
Docket ID No. EPA-HQ-OAR-2003-0189-0014.
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On August 28, 2019, the EPA received the petition being acted on
here, which seeks to remove the Stationary Combustion Turbines source
category from the list of categories of major sources under CAA section
112. The petitioners submitted a supplement to the source category
delisting petition on November 21, 2019; a second supplement to the
source category delisting petition on December 2, 2020; and a revised
version of the second supplement to the delisting petition on March 15,
2021. The EPA has fully considered all the petitioners' submissions in
this final decision to deny the petition. Delisting of the Stationary
Combustion Turbines source category from the list of major sources
would result in removal of the regulatory requirements specified in the
NESHAP for Stationary Combustion Turbines in 40 CFR 63.6080-6175 of 40
CFR part 63, subpart YYYY.
II. Treatment of Petitions To Delist a Source Category From Regulation
Under CAA Section 112
In this section, the EPA sets out the specific criteria under the
CAA that apply for removing a source category from the list of source
categories. CAA section 112(c)(9)(B) specifies certain criteria that
must be satisfied in order for the EPA to grant a petition to remove a
source category from the list of source categories regulated for HAP
emissions. The EPA's consideration of petitions to delist is bound by
these criteria and informed by prior court decisions interpreting this
provision of the CAA.
A. What is a source category delisting petition and what are the
criteria for delisting a source category?
A source category delisting petition is a formal request to the EPA
from an individual or group to remove a specific source category from
the CAA section 112 list of categories of major sources and area
sources under CAA section 112(c)(9)(B). The Administrator must grant or
deny such a petition to delete a source category within 1 year after a
petition is filed and is determined to be complete.\6\ See CAA section
112(c)(9)(B). Delisting of a source category would result in the
removal of applicable regulatory requirements under CAA section 112 for
such source category. CAA section 112(c)(9)(B) contains the
discretionary authority to delist a source category and provides in
relevant part: ``The Administrator may delete any source category from
the list under this subsection, on petition of any person or on the
Administrator's own motion, whenever the Administrator makes the
following determination or determinations, as applicable: [. . .].''
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\6\ As stated previously, the EPA has determined that the
current petition to delist the Stationary Combustion Turbines source
category is not complete.
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CAA section 112(c)(9)(B) further specifies three criteria for
deletion of a source category from the list. The first criterion is
specific to carcinogenic HAP and is specified in CAA section
112(c)(9)(B)(i). The criterion states that, in the case of HAP emitted
by sources in the category that may result in cancer
[[Page 26838]]
in humans, a determination must be made that ``no source in the
category (or group of sources in the case of area sources) emits such
hazardous air pollutants in quantities which may cause a lifetime risk
of cancer greater than one in one million to the individual in the
population who is most exposed to emissions of such pollutants from the
source (or group of sources in the case of area sources).''
The second criterion is specific to non-carcinogenic HAP and the
third criterion is specific to environmental effects. These criteria
are specified in CAA section 112(c)(9)(B)(ii). In the case of HAP that
may result in adverse health effects in humans other than cancer or
adverse environmental effects, the second criterion states that a
determination must be made that ``emissions from no source in the
category or subcategory concerned (or group of sources in the case of
area sources) exceed a level which is adequate to protect public health
with an ample margin of safety'' and the third criterion states that a
determination must be made that ``no adverse environmental effect will
result from emissions from any source (or from a group of sources in
the case of area sources).''
Further, to assist the EPA in making judgments about whether a
pollutant causes adverse environmental effects, CAA section 112(a)(7)
defines an ``adverse environmental effect'' as ``[A]ny significant and
widespread adverse effect, which may reasonably be anticipated, to
wildlife, aquatic life, or other natural resources, including adverse
impacts on populations of endangered or threatened species or
significant degradation of environmental quality over broad areas.''
For source categories that emit carcinogenic HAP, CAA section
112(c)(9)(B)(i) sets a lifetime cancer risk threshold for delisting of
1-in-1 million. This level differs from the acceptable risk
determination used in other rulemakings under CAA section 112. For
instance, for standards promulgated under CAA section 112(f)(2), an
excess lifetime cancer risk to the most exposed individual of 100-in-1
million is ordinarily the upper bound of acceptability. This level was
established in the Benzene NESHAP (54 FR 38044; September 14, 1989) and
was incorporated into the 1990 CAA Amendments in CAA section
112(f)(2)(B).\7\
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\7\ The maximum individual lifetime cancer risk is the
``estimated risk that a person living near a plant would have if he
or she were exposed to the maximum pollutant concentrations for 70
years.'' National Emissions Standards for Hazardous Air Pollutants:
Benzene Emissions from Maleic Anhydride Plants, Ethylbenzene/Styrene
Plants, Benzene Storage Vessels, Benzene Equipment Leaks, and Coke
By-Product Recovery Plants (Benzene NESHAP) (54 FR 38044, 38045;
September 14, 1989).
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When considering delisting decisions under CAA section
112(c)(9)(B), the EPA construes this provision as calling for a high
level of confidence before a determination can be made that the
criteria for delisting are satisfied. For example, for purposes of
deleting the non-mercury cell chlorine production subcategory under CAA
section 112(c)(9)(B)(ii), the EPA ``obtained chlorine and HCl emission
estimates from every known major source facility in the non-mercury
cell chlorine production subcategory using our authority under section
114 of the CAA and conducted risk assessments for each facility.'' \8\
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\8\ National Emission Standards for Hazardous Air Pollutants:
Chlorine and Hydrochloric Acid Emissions from Chlorine Production:
Final decision to delete subcategory (68 FR 70948, 70951; December
19, 2003). See also 66 FR 21933, where the EPA explained and agreed
with the use of certain health effect studies in delisting petition
for Methanol. (``As the [Health Effects Institute] Health Review
Committee noted in its commentary, the experiments in this study
were `well designed and executed with appropriate quality control
and quality assurance procedures. Thus, one can have confidence in
the data.' '').
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For source categories that emit HAP that may result in adverse
health effects (non-cancer risks), CAA section 112(c)(9)(B)(ii)
requires HAP emissions to be below a level providing an ample margin of
safety. In the context of a source category delisting and CAA section
112(c)(9)(B)(ii), the EPA interprets an ``ample margin of safety'' as
such that the chronic and acute concentrations that a person may be
exposed to should be less than the concentrations that may elicit an
adverse non-cancer health effect (i.e., each of the ratios should be
less than one). This interpretation has been applied in a prior
subcategory delisting action under CAA section 112(c)(9)(B)(ii) for the
non-mercury cell chlorine production subcategory (68 FR 70947).
For the purposes of determining whether the delisting criteria
under CAA section 112(c)(9)(B) are satisfied, risk evaluations must be
based on emission estimates that assume the controls required under CAA
section 112 are not in place unless they are also known to be required
under a different regulatory authority. This is because a final notice
granting a delisting petition of, for example, the Stationary
Combustion Turbines source category from the list of major sources
would result in removal of the regulatory requirements specified in the
NESHAP for stationary combustion turbines.
The EPA views CAA section 112(c)(9)(B) as providing discretionary
authority for delisting source categories that satisfy the criteria
contained therein. ``The Administrator may delete any source category
from the list under this subsection, on petition of any person . . . ,
whenever the Administrator makes the following determination or
determinations, as applicable,'' (CAA section 112(c)(9)(B) (Emphasis
added)). The Agency reads this provision as allowing for delisting of a
source category upon the Administrator determining that the statutory
criteria are satisfied. However, it does not foreclose the exercise of
the Administrator's discretion in forming a final decision on whether
to delist. (``The Administrator may delete . . .'' and not ``The
Administrator [must] delete . . .'' (Emphasis supplied). The EPA
interprets ``may'' in CAA section 112(c)(9)(B)(i) as being directional
towards a determination that is based on reasonably health protective
assumptions to account for uncertainties in any supporting analysis.
The final decision involves the consideration and balancing of factors
that are uniquely within the Administrator's expertise, including
policy choices, and predictions on ``the frontiers of scientific
knowledge.'' Nat'l Lime Ass'n v. EPA, 627 F.2d 416, 454 (D.C. Cir.
1980).\9\
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\9\ ``[A]n agency [has] latitude to exercise its discretion in
accordance with the remedial purposes of the controlling statute
where relevant facts cannot be ascertained or are on the frontiers
of scientific inquiry.'' 627 F.2d 454.
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Questions as to whether pollutant emissions from a source category
present adverse health and environmental effects and questions
regarding the kinds of effects that can come from exposure to those
emissions may, in certain instances, border on the frontiers of
scientific knowledge and are given to be quite uncertain due to either
insufficient or inconsistent data.\10\ For example, there could be
limited scientific knowledge of the effects of pollutant exposure on
human health and the environment. There could also be limited emissions
data from the source category. Further, some
[[Page 26839]]
pollutants have no known safe level of exposure.\11\ The Administrator
is not required to base his determination solely on a single parameter
or measure and has the discretion to weigh various factors or data
differently. The Administrator's decision to delist (or to deny a
petition to delist) a source category is made on a case-by-case basis
and involve a thorough and comprehensive review of factual issues,
scientific evidence, and data provided in support of a delisting
petition.
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\10\ ``Where a statute is precautionary in nature, the evidence
difficult to come by, uncertain, or conflicting because it is on the
frontiers of scientific knowledge, the regulations designed to
protect the public health, and the decision that of an expert
administrator, we will not demand rigorous step-by-step proof of
cause and effect. Such proof may be impossible to obtain if the
precautionary purpose of the statute is to be served.'' Id., at 454
n.143 citing Ethyl Corp. v. EPA, 541 F.2d 1, 28-29 (D.C. Cir. 1976).
\11\ ``The Administrator may apply his expertise to draw
conclusions from suspected, but not completely substantiated,
relationships between facts, from trends among facts, from
theoretical projections from imperfect data, from probative
preliminary data not yet certifiable as `fact,' and the like.'' Id.
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The EPA also views CAA section 112(c)(9)(B) as allowing the
Administrator to balance the likelihood of adverse health effects
against limited scientific data and to err on the side of caution in
making decisions considering uncertainties in scientific data. Any
projections, assessments, and estimations must be reasonable and not
based on conjecture. While use of the term ``adequate''' further
indicates that the Administrator must weigh the potential uncertainties
and their likely significance, uncertainties concerning the risks of
adverse health or environmental effects may be mitigated if the
Administrator can determine that projected exposures are sufficiently
low to provide reasonable assurance that adverse health effects will
not occur. Similarly, uncertainties concerning the magnitude of
projected exposures may be mitigated if the Administrator can determine
that the levels which might cause adverse health or environmental
effects are sufficiently high to provide reasonable assurance that
exposures will not reach harmful levels. But as a part of the requisite
demonstration called for by CAA section 112(c)((9)(B), a petitioner
must present data that are adequate to support a delisting decision,
and thus, resolve any uncertainties associated with missing
information.
The Administrator will not remove a source category from the list
of source categories covered under CAA section 112 merely because of
the inability to conclude that HAP emissions from sources within that
source category will cause adverse effects on human health or the
environment. Thus, the EPA will not grant a petition to remove a source
category if there are uncertainties relating to health effects or if
the Administrator does not have sufficient information to make the
requisite determination under CAA section 112(c)(9)(B).\12\ We note
that the Administrator's discretion is neither unbounded nor limitless,
but rather constrained by the EPA's duty to protect human health and
welfare.\13\ This is because the CAA is a protective or preventive
statute \14\ considering that one of its stated purposes under CAA
section 101(b)(1) is ``to protect and enhance the quality of the
Nation's air resources so as to promote the public health and
welfare.'' Such statutes do not call for certitude of harm but rather
accord a decision maker discretion and flexibility in taking regulatory
action that is protective of both public health and the environment.
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\12\ See American Forest and Paper Ass'n v. EPA 294 F.3d 113,
119 (D.C. Cir. 2002) (upholding the EPA's denial of the petition to
delist methanol as a HAP) ``EPA's interpretation easily passes
muster under Chevron. The statutory language unambiguously places on
a delisting petitioner the burden to make a showing that there is
adequate data about a substance to determine exposure to it may not
reasonably be anticipated to cause adverse effects. This is
precisely what EPA has construed it to require.'' (Emphasis in
original; cleaned up) (66 FR 21930; May 2, 2001) (Where the
Administrator is acting on a delisting petition, ``the burden
remains on a petitioner to demonstrate that the available data
support an affirmative determination that emissions of a substance
may not be reasonably anticipated to result in adverse effects on
human health or the environment.'').
\13\ See Massachusetts v. EPA, 127 S. Ct. 1438, 1462. (The goal
of the CAA is ``to protect and enhance the quality of the Nation's
air resources so as to promote the public health and welfare and the
productive capacity of its population.'' CAA section 101(b)(1)).
\14\ Ethyl Corp., 541 F.2d at 29 n.56 (``Under the Clean Air Act
the Administrator's flexibility is derived not from a command to
act, but from a precautionary statute that necessarily includes risk
assessment if its preventive purpose is to be achieved.''). The CAA
is ``to assure that regulatory action can effectively prevent harm
before it occurs; to emphasize the predominant value of protection
of public health.'' H.R. Rep. No. 95-294, 95th Cong., 1st Sess. 49
(1977).
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Further, when considering delisting petitions under CAA section
112(c)(9)(B), the EPA is guided by relevant decisions of the United
States Court of Appeals for the District of Columbia (D.C. Circuit or
court). Specifically, in 2007, the court held in Natural Resources
Defense Council v. EPA, 489 F.3d 1364, 1373 (D.C. Cir. 2007) (vacating
portions of the Plywood Maximum Achievable Control Technology (MACT)
standards), that the EPA had no authority to create and delist a ``low-
risk subcategory'' under CAA section 112(c)(9)(B)(i).\15\ According to
the court, only subcategories with no carcinogenic HAP emissions and
satisfying CAA section 112(c)(9)(B)(ii) could be removed from the CAA
section 112(c)(1) list of categories and subcategories (e.g., deletion
of the non-mercury cell chlorine production subcategory (68 FR 70947;
December 19, 2003)). Otherwise, subcategories with any carcinogenic HAP
emissions could only be removed as part of a complete removal of the
entire source category under CAA section 112(c)(9)(B)(i), noting that
the criteria in CAA section 112(c)(9)(B)(ii) would also need to be
satisfied if applicable.
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\15\ To accord with this decision, the EPA is denying the
petition to delist two subcategories of stationary combustion
turbines that the EPA received during the 2004 Stationary Combustion
Turbines NESHAP rulemaking.
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Further, in another key case, New Jersey v. EPA, 517 F.3d 574, 582
(D.C. Cir. 2008), the court vacated the EPA's action that delisted
coal- and oil-fired electric utility steam generating units (EGUs)
holding that ``because section 112(c)(9) governs the removal of `any
source category' from the section 112(c)(1) list, and nothing in the
CAA exempts EGUs from section 112(c)(9), the only way the EPA could
remove EGUs from the section 112(c)(1) list was by satisfying section
112(c)(9)'s requirements.'' (Emphasis in original). Since then, the
court has upheld our reading of CAA section 112(c)(9) as calling for
application of criteria contained therein.\16\ For instance, in White
Stallion Energy Ctr., LLC v. EPA, 748 F.3d 1222 (D.C. Cir. 2013) the
court upheld the EPA's denial of a petition to delist coal-fired EGUs
finding that the EPA was correct in rejecting a delisting petition
because it ``did not demonstrate that EPA could make either of the two
predicate findings required for delisting under section 112(c)(9)(B).''
Id., at 1248. Additionally, in American Forest and Paper Ass'n v. EPA,
294 F.3d at 119 (construing section 112(b) and upholding the EPA's
denial of the petition to delist methanol as a HAP), the court held
that ``[t]he statutory language unambiguously places on a delisting
petitioner the burden to make a showing that there is adequate data
about a substance to determine exposure to it may not reasonably be
anticipated to cause adverse effects.''
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\16\ See U.S. Sugar Corp. v. EPA, 830 F.3d 579 (D.C. Cir. 2016)
(upholding the EPA's decision to remove source categories from CAA
section 112(c)(6) without applying CAA section 112(c)(9)).
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Finally, an additional relevant decision addresses setting MACT
standards for listed source categories under CAA section 112. In
Louisiana Environmental Action Network v. EPA, 955 F.3d 1088 (D.C. Cir.
2020) (LEAN), the court held that when the ``EPA reviews an existing
standard that fails to address many of the listed air toxics the source
category emits, adding limits for those overlooked toxics is a
`necessary' revision under section 112(d)(6).'' Id., at 1091. The EPA
must now set MACT
[[Page 26840]]
standards in the context of a CAA section 112(d)(6) review where there
are gaps in existing MACT standards.
B. What is the process for delisting a source category?
In this section, the EPA describes the Agency's process for
consideration of petitions to delist source categories under CAA
section 112(c)(9)(B).
Although the delisting action for a listed source category is not
subject to the formal rulemaking procedures under CAA section 307(d),
it is the EPA's practice to publish and solicit public comments on
relevant aspects of the Agency's consideration of such a complete
petition in the Federal Register. See American Forest and Paper Ass'n
v. EPA, 294 F.3d 113, 117 n.3 (D.C. Cir. 2002) (``Section 112(b) does
not contemplate a formal rulemaking and is not among the sections
enumerated in section 307(d)(1) (although other subsections of section
112 are included there).'').
The EPA's petition review process proceeds in two phases: a
completeness determination and a technical review.\17\ During the
completeness determination, we conduct a broad review of the petition
to determine whether all the necessary subject areas are addressed and
whether reasonable information and analyses are presented for each of
these subject areas.\18\ Once the petition is determined to be
complete, we place a notice of receipt of a complete petition in the
Federal Register.\19\ That Federal Register document announces a public
comment period on the petition and starts the technical review phase of
our decision-making process. The technical review involves a thorough
scientific review of the petition to determine whether the data,
analyses, interpretations, and conclusions in the petition are
appropriately supported and technically sound. The technical review
will also determine whether the petition satisfies the necessary
requirements of CAA section 112(c)(9)(B) and adequately supports a
decision to delist the source category. All comments and data submitted
during the public comment period are considered during the technical
review. The decision to either grant or deny a petition is made after a
comprehensive technical review of both the petition and the information
received from the public to determine whether the petition satisfies
the requirements of CAA section 112(c)(9)(B). Here, the review process
is not proceeding to the second phase due to the EPA's determination
that the petition is incomplete because the petitioners did not address
all the necessary subject areas under CAA section 112(c)(9)(B) and did
not present reasonable information and analyses for each these subject
areas.
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\17\ See, e.g., 70 FR 30407; May 26, 2005 (Notice of receipt of
a complete petition to delist 4,4'- methylene diphenyl diisocyanate
as a HAP); 64 FR 42125; August 3, 1999 (Notice of receipt of a
complete petition to delist ethylene glycol monobutyl ether as a
HAP); 64 FR 38668, 38669; July 19, 1999 (Notice of receipt of a
complete petition to delist methanol as a HAP); 64 FR 33453; June
23, 1999 (Notice of receipt of a complete petition to delist Methyl
Ethyl Ketone as a HAP).
\18\ As an additional and separate independent basis for denial,
the EPA may deny a petition that is not complete if the petitioners
did not address all the necessary subject areas under CAA section
112(c)(9)(B) and did not present reasonable information and analyses
for each of the subject areas. See, e.g., Notice of denial of
petition to delist five glycol ethers as a HAP (58 FR 4164, 4165;
January 13, 1993) (The EPA explained that: ``Although public
information indicated that over 140 million pounds of these
substances are used annually in the U.S. and that there is a general
trend towards greater usage, the petitioner did not provide
measurements or estimates regarding the emissions associated with
such use. In the absence of such information, EPA cannot make the
substantive determination contemplated by CAA Section 112(b)(3)'').
\19\ The EPA did not make a completeness determination for the
petition because the petitioners did not address all the necessary
subject areas under CAA section 112(c)(9)(B) and did not present
reasonable information and analyses for each these subject areas.
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If the Administrator decides to grant a petition, the Agency
publishes a written explanation of the Administrator's decision, along
with a proposed rule to delete the source category. The proposed rule
is open to public comment and public hearing and all additional
substantive information received is considered prior to the issuance of
a final rule.\20\ If the Administrator decides to deny the petition,
the Agency publishes a notice of its denial, along with a written
explanation of the basis for denial.\21\ A decision to deny a petition
is a final Agency action subject to review in the Circuit Court of
Appeals for the District of Columbia under CAA section 307(b).
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\20\ See, e.g., 68 FR 65648; November 21, 2003 (Proposal to
Delist Ethylene Glycol Monobutyl Ether: Request for Comment); 68 FR
32605; May 30, 2003 (Proposed Rule to Delist Methyl Ethyl Ketone
(MEK): Request for Comment).
\21\ See, e.g., 66 FR 21929; May 2, 2001 (Denial of the petition
to delist methanol as a HAP).
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A denial of a petition may take one of two forms. The EPA may deny
the petition with prejudice, in which case any future petition will be
denied as a matter of law unless it is accompanied by substantial new
evidence; or the EPA may deny the petition without prejudice, in which
case the EPA will consider future petitions without the presentation of
substantial new evidence. The EPA will issue a denial with prejudice
when there are adequate data available that lead the EPA to conclude
that emissions from a source category may cause a lifetime risk of
cancer greater than 1-in-1 million to the individual in the population
who is most exposed to emissions of pollutants from a source category;
or where there are adequate data available that lead the EPA to
conclude that emissions from a pollutant can be anticipated to result
in adverse effects to human health or the environment. Additionally,
the EPA will issue a denial with prejudice when the EPA concludes that
the available evidence cannot support a determination that emissions
from a source category may not cause a lifetime risk of cancer greater
than 1-in-1 million to the individual in the population who is most
exposed to emissions of such pollutants; or when the EPA concludes that
the available evidence cannot support a determination that emissions
from the source category may not reasonably be anticipated to result in
adverse effects to human health or the environment and, therefore, that
substantial new information or analyses would be necessary to allow the
Agency to make the requisite determination under CAA section
112(c)(9)(B).\22\
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\22\ A denial with prejudice serves a vital administrative
purpose. It prevents the endless resubmission of essentially
identical petitions (with only peripheral or trivial changes) in the
wake of an EPA decision on the merits of a petition. Thereby, once
the EPA has denied a petition to delist based on a full
consideration of the merits, any future petition to remove the same
source category will not trigger another full evaluation of the
merits unless it includes substantial data or analyses that were not
present in the earlier petition. Conversely, the EPA may issue a
denial without prejudice, for example, where there has not been a
complete examination of the merits of a petition, and where,
therefore, the EPA has not reached a decision on the petition that
is based on a robust evaluation of the underlying technical data and
analyses. For example, where a petition obviously lacks some element
necessary for the EPA to properly evaluate the petition, the EPA may
deny such petition without prejudice and allow the petitioner to re-
submit the petition with the necessary additional information
without a determination that the additional information constitutes
substantial new data or analysis. See, e.g., Notice of Denial (58 FR
4164; January 13, 1993) (denying without prejudice a petition to
remove five glycol ethers from the list of HAP).
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III. Risk Review Methodology and Findings
In this section, the Agency presents the risk assessment and risk
assessment methodology that are the underpinnings of the findings for
the 2020 RTR for the Stationary Combustion Turbines source category
under CAA section 112(f)(2). It bears note that under CAA section
112(f)(2) the excess lifetime cancer risk to the most exposed
individual of 100-in-1 million is ordinarily the upper
[[Page 26841]]
bound of acceptability, in contrast to CAA section 112(c)(9)(B)(i)
which sets out a risk threshold of 1-in-1 million for delisting source
categories that emit carcinogenic HAP. On April 12, 2019, the EPA
proposed the RTR for the Stationary Combustion Turbines NESHAP (84 FR
15046). The EPA finalized the RTR on March 9, 2020, and based on the
risk assessment performed for this source category readopted the
existing standards under CAA section 112(f)(2) (85 FR 13524).\23\
Additional emissions data collection efforts by the EPA after the 2020
RTR are also discussed in this section.
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\23\ 85 FR at 13530. (See NRDC v. EPA, 529 F.3d at 1083. ``If
EPA determines that the existing technology-based standards provide
an `ample margin of safety,' then the Agency is free to readopt
those standards during the residual risk rulemaking.'').
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A. The EPA's Risk Assessment Methodology
The EPA's risk assessment methodology for the 2020 RTR is described
in detail in the Residual Risk Assessment for the Stationary Combustion
Turbines Source Category in Support of the 2020 Risk and Technology
Review Final Rule, Docket ID No. EPA-HQ-OAR-2017-0688-0131 (``Risk
Report''). The risk assessment estimated the maximum individual
lifetime cancer risk, population at increased cancer risk, total
estimated cancer incidence, maximum chronic non-cancer hazard index,
and maximum acute non-cancer risk hazard quotient. The EPA performed a
three-tier screening assessment of the potential multipathway health
risks, as well as a three-tier screening assessment of the potential
adverse environmental risks. The risk modeling dataset includes
emissions data for three emissions scenarios: actual emissions,
allowable emissions, and acute emissions.
B. The EPA's 2020 Risk Review Findings
Pursuant to CAA section 112(f)(2), the EPA conducted a residual
risk review for the Stationary Combustion Turbines source category.
Risk modeling was conducted for all the facilities known by the EPA at
the time to be subject to the Stationary Combustion Turbines NESHAP,
which totaled 253 stationary combustion turbine facilities. Additional
information obtained after risk modeling refined our estimate of
facilities in the source category to 244. The total emissions of HAP
from modeled facilities were approximately 5,300 tons per year. The HAP
emitted in the largest quantities were formaldehyde, n-hexane,
acetaldehyde, toluene, xylenes (mixed), hydrochloric acid, propylene
oxide, ethyl benzene, benzene, and acrolein. Emissions of these
pollutants made up over 99 percent of the total HAP emissions by mass.
Emissions of persistent and bioaccumulative HAP (PB-HAP) included lead
compounds, arsenic compounds, cadmium compounds and mercury compounds.
Emissions of environmental HAP included the above PB-HAP plus
hydrochloric acid.
The results of the chronic inhalation cancer risk assessment based
on actual emissions indicated that the estimated maximum individual
lifetime cancer risk was 3-in-1 million, with formaldehyde,
acetaldehyde, propylene oxide and arsenic compounds from combustion
turbines as the major contributors to the risk. The total estimated
cancer incidence was 0.04 excess cancer cases per year, or one excess
case in every 25 years. Approximately 153,000,000 people live within 50
kilometers of the 253 modeled facilities, and 42,000 people were
estimated to have cancer risks at or above 1-in-1 million. The 2020
RTR, where the Agency was acting under CAA section 112(f)(2), showed
that the Stationary Combustion Turbines source category did not meet
the statutory criteria for delisting described in section II.A. of this
preamble. More information concerning the risk analysis can be found in
the Risk Report.
C. CAA Section 114 Information Request
In May 2020, the EPA received a petition for reconsideration of the
2020 RTR. One of the issues listed in the petition for reconsideration
was the EPA's failure to set limits for unregulated HAP in the
Stationary Combustion Turbines NESHAP, citing LEAN. The EPA granted the
petition for reconsideration on August 13, 2020. In April 2022, the
EPA, acting under authority of CAA section 114, requested operating
information and emissions data from six companies that own and operate
turbines subject to the Stationary Combustion Turbines NESHAP. A
request was sent to a seventh company in September 2022. The requests
were sent for the purpose of obtaining emissions data to be used in an
upcoming separate rulemaking to establish emission standards for
turbines subject to the Stationary Combustion Turbines NESHAP that do
not currently have standards in the rule. Requests for operating
information included annual hours of turbine operation and annual
turbine heat input for 2016-2020. Responses were required within 3
months of receipt of the request. The request mandated testing of
selected turbines for emissions of formaldehyde, acid gases (hydrogen
fluoride and hydrogen chloride), metallic HAP, particulate matter (PM),
and carbon monoxide. The 22 turbines that were tested ranged in size
from 1 to 269 MW and included both simple cycle and combined cycle
units. The turbines were operated on natural gas, distillate oil, or
landfill gas. Some turbines were equipped with an oxidation catalyst.
Submittal of the required data from emissions testing was required
within 9 months of receipt of the request. The responses to the
requests are included in the docket for this action, Docket ID No. EPA-
HQ-OAR-2020-0408.
IV. Evaluation of the Petition
In this section, the EPA presents the details of the petition to
delist and of the Agency's technical evaluation of the petition. In
section IV.A., the EPA presents the details of the petition to delist;
and, in section IV.B., the EPA presents the petitioners' risk
assessment methodology. In section IV.C., the EPA discusses
deficiencies in the petitioners' estimates of HAP emissions for the
Stationary Combustion Turbines source category; and, in section IV.D.,
the EPA presents the gaps in the petitioners' data that include missing
emissions data from a large number of affected sources and uncertainty
in the HAP emission estimates for the Stationary Combustion Turbines
source category.
In general, the EPA found that the petitioners did not present
reasonable and complete information and analyses for each of the
affected sources, such as HAP emission measurements from stack testing
or fuel content analyses for all sources subject to the Stationary
Combustion Turbines source category. In the absence of such requisite
information, the EPA did not make a completeness determination for the
petition. And, in conducting the technical review of the information
provided, the EPA cannot make the substantive determination
contemplated under CAA section 112(c)(9)(B).
A. Description of the Petition
As stated previously, on August 28, 2019, the EPA received a joint
petition from the American Fuel & Petrochemical Manufacturers, the
American Petroleum Institute, the American Public Power Association,
the Gas Turbine Association, the Interstate Natural Gas Association of
America, and the National Rural Electric Cooperative Association to
remove the Stationary Combustion Turbines source category from the list
of categories of major sources regulated under CAA section
[[Page 26842]]
112. That petition claimed that the HAP emissions from affected sources
in the Stationary Combustion Turbines source category that were
identified in the proposed RTR meet the criteria for delisting. The
petitioners submitted the first supplement to the petition on November
21, 2019. That supplement included risk analyses for additional units
that were identified in a comment to the proposed RTR for the
Stationary Combustion Turbines NESHAP. The petitioners claimed that all
three statutory criteria for delisting were satisfied based on the
results of this risk assessment.
After receipt of the first supplement to the petition, a second set
of additional turbines that were not evaluated in either the petition
or first supplement to the petition were identified by the EPA as being
subject to the rule. The EPA therefore requested that the petitioners
provide analyses for the second set of additional units. The EPA also
asked for further explanation on the following issues: (1) whether the
petitioners' analyses were based on emission factors without
corroboration by emissions data and whether it accounted for operation
of units at partial loads; (2) whether arsenic emission factors used in
the petition analyses would be adequately justified for oil-fired
turbines; and (3) whether the acute multiplier used in estimating acute
risk at two facilities was adequately justified. The petitioners
submitted a second supplement to the petition on December 2, 2020, in
response to the EPA's concerns regarding the completeness of the
petition. Finally, the petitioners submitted a revised version of the
second supplement on March 15, 2021, correcting an error in the
estimated hexavalent chromium emissions at one source. The petition and
all the supplements to the petition are available for review in the
docket, Docket ID No. EPA-HQ-OAR-2020-0408. The EPA has fully
considered all the petitioners' submissions in this decision to deny
the petition.
In general, the petitioners' initial petition and subsequent
supplements to the petition provided both revised HAP emission
estimates and a revised evaluation of the 2020 RTR risk analysis.\24\
The petitioners revised HAP emission estimates and revised risk
evaluation, however, were primarily based on emission factors and
historical fuel usage data for a subset of the turbines that are
subject to CAA section 112.
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\24\ As described in section III.B. of this preamble, the 2020
RTR showed that the Stationary Combustion Turbines source category
did not meet the statutory criteria for delisting.
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The initial petition and supplements provided by the petitioners
contained the following information:
<bullet> Revised emission estimates for formaldehyde, which is one
of the organic HAP that is a contributor to risk for stationary
combustion turbines firing natural gas or distillate fuel oil;
<bullet> Revised emission estimates for arsenic, which is one of
the metallic HAP that is a contributor to risk for stationary
combustion turbines;
<bullet> Revised emission estimates for other HAP (organic and
metallic) based on fuel use, emission factors, and permit limits for
volatile organic compounds (VOCs);
<bullet> Measurements of the arsenic content in distillate fuel oil
at certain facilities;
<bullet> Revised acute emission estimates for certain facilities;
<bullet> Other revisions including adjustments to stack parameters
and locations, and removal of sources that were no longer operating;
<bullet> Analyses of the inhalation acute and chronic (cancer and
non-cancer) risks for each source in the category, based on the revised
HAP emission estimates;
<bullet> Analyses of the multipathway chronic (cancer and non-
cancer) risks for each source in the category, based on the revised HAP
emission estimates;
<bullet> Analyses of the environmental effects, based on the
revised and updated emission estimates; and
<bullet> New emission estimates and analyses for the facilities not
previously reviewed in the 2020 RTR risk analysis.
The petitioners argued that delisting of the source category was
warranted based on the following results from their analyses:
<bullet> A maximum lifetime inhalation cancer risk for the most
exposed individual of 0.76-in-1 million;
<bullet> A maximum acute inhalation hazard quotient (i.e., the
ratio of acute exposure concentration to the concentration at which no
acute adverse health effect is observed) of 0.52;
<bullet> A maximum chronic (non-cancer) inhalation hazard index
(i.e., the ratio of chronic exposure concentration to the concentration
at which no chronic adverse health effect is observed) of 0.03;
<bullet> A maximum multipathway cancer risk for the most exposed
individual of 0.007-in-1 million; and
<bullet> A maximum multipathway chronic hazard index of 0.12.
<bullet> All facilities were below environmental screening
thresholds.
B. Petitioners' Risk Assessment Methodology
As previously referenced, the petitioners' initial petition and
subsequent supplements to the petition provided both revised HAP
emission estimates and a revised evaluation of the 2020 RTR risk
analysis. The petitioners also included risk analyses that covered
additional units that were identified by the EPA as subject to the
Stationary Combustion Turbines NESHAP after submittal of the initial
petition. The petitioners' risk assessments, however, did not address
whether the emission controls that reduce HAP emissions, such as
oxidation catalysts, that are installed on some turbines were installed
due to the requirements of the Stationary Combustion Turbines NESHAP or
for other regulatory requirements.\25\ The petitioners' risk
assessments also did not address the effect of delisting the Stationary
Combustion Turbines source category on the emission estimates used for
their analysis. This is requisite information because deleting a source
category from the list of major sources would result in removal of the
regulatory requirements specified in the applicable NESHAP.
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\25\ As mentioned previously, the EPA proposed to remove the
stay of effectiveness of the standards for new lean premix gas-fired
and diffusion flame gas-fired turbines on April 12, 2019 (84 FR
15046), prior to the submittal of the petition to delist in August
2019. The EPA finalized the removal of the stay on March 9, 2022 (87
FR 13183).
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In some instances, the petitioners performed additional analyses
that they claimed made their results more conservative. For inhalation
risks, the petitioners conducted an additional analysis that accounted
for the effects of building downwash,\26\ which they indicated has the
potential to increase risk. The petitioners also evaluated the non-
cancer risks by summing the hazard quotients among all HAP regardless
of the target organ. For multipathway health risks, the petitioners
further performed a site-specific multipathway risk assessment for one
facility with five stationary combustion turbines. According to the
petitioners' multipathway risk assessment, four of those units
exclusively fire natural gas while one fires refinery fuel gas. This
facility was evaluated in the initial petition risk analysis and was
re-evaluated in the first supplement to the petition. All other
facilities showed low multipathway risks in a more general analysis by
the petitioners and so they
[[Page 26843]]
did not perform site-specific multipathway risk assessments.
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\26\ Downwash means the downward movement of pollutant plumes
immediately after stack release due to obstacles such as buildings
or smokestacks.
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In general, the risk assessment methodology used in the
petitioners' analyses estimated the same risk parameters as those used
by the EPA in the risk assessment for the 2020 RTR, including maximum
individual lifetime cancer risk, population at increased cancer risk,
total estimated cancer incidence, maximum chronic non-cancer hazard
index, maximum acute non-cancer risk hazard quotient, multipathway
health risks, and adverse environmental risks. However, while the
petitioners' risk modeling methodology was similar to the EPA's, there
are deficiencies in the petitioners' estimates of the emissions from
the source category which were used to determine the values of the
petitioners' risk modeling results, as discussed further in sections
IV.C. and IV.D.
C. Basis for Emission Estimates
The following section discusses deficiencies in the petitioners'
analyses that support the EPA's conclusions that the petition is
incomplete and that there are inadequate data to determine that no
source in the category emits HAP in quantities which may cause a
lifetime risk of cancer greater than 1-in-1 million to the individual
in the population who is most exposed to emissions of such pollutants
from the source.
The EPA identified several deficiencies in the submitted petition.
First, the petitioners relied on emission factors and fuel sampling
which are not adequate for determining site-specific emissions with the
necessary certainty; and the petitioners failed to provide any site-
specific emissions testing data. Notably, the Agency afforded
petitioners the opportunity to provide additional information and data,
which petitioners declined. Second, the petitioners significantly
underestimated the formaldehyde emissions from some turbines, as
demonstrated by site-specific turbine formaldehyde emissions testing
data collected by the EPA. Third, to assess the potential health
impacts from short-term exposures, the petitioners used a multiplier
for acute risks that is far lower than the standard multiplier the EPA
applied in the 2020 RTR, which was supported by measured emissions
data, and the petitioners did not explain why their multiplier is more
appropriate than the EPA's own multipliers. And fourth, the petitioners
failed to explain whether the emission estimates they used would
continue to be applicable if the source category were delisted.
1. Reliance on Emission Factors
As stated previously, a source category may be delisted only if the
EPA has a high level of confidence that emissions from no source in the
category or subcategory exceed a level which is adequate to protect
public health with an ample margin of safety. The emission estimates
used by the petitioners to assess the risks from the source category
relied almost entirely on emission factors. The EPA has long viewed
emission factors as not supplying sufficient certainty regarding site-
specific emissions that would provide confidence that no source in the
category exceeds the criteria for delisting. While emission factors are
a widely used tool for estimating emissions, the EPA as well as state
and local air pollution control agencies usually prefer data from
source-specific emission tests or continuous emission monitoring
systems (CEMS) for estimating a source's emissions because those data
provide the best representation of the source's emissions. The EPA
notes that the introduction to AP-42: Compilation of Air Emission
Factors from Stationary Sources states that ``[b]ecause emission
factors essentially represent an average of a range of emission rates,
approximately half of the subject sources will have emission rates
greater than the emission factor and the other half will have emission
rates less than the emission factor.'' \27\ In the same document, the
EPA also noted that ``[a]verage emissions differ significantly from
source to source and, therefore, emission factors frequently may not
provide adequate estimates of the average emissions for a specific
source.'' Further, for example, the North Carolina Department of
Environmental Quality states the following regarding estimating
emissions: ``Usually, results from continuous emission monitoring data
are the preferred way to establish emissions. However, this is not
often possible or practical, except for larger facilities such as
electric utilities. Use of site-specific stack tests under a single or
a range of representative conditions is usually the next preferable
method.'' \28\ After receipt of the initial petition and first
supplement, the EPA requested that the petitioners provide HAP emission
measurements from stack testing to corroborate the HAP emissions
estimated by the petitioners based on emission factors and fuel content
analyses, where possible. In response to the EPA's request, however,
the petitioners indicated via email that a ``detailed measurement
campaign is out of the scope for this study.'' \29\
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\27\ <a href="https://www.epa.gov/air-emissions-factors-and-quantification/ap-42-compilation-air-emissions-factors-stationary-sources">https://www.epa.gov/air-emissions-factors-and-quantification/ap-42-compilation-air-emissions-factors-stationary-sources</a>. Fifth Edition. January 1995.
\28\ The Basics of Estimating Air Emissions. North Carolina
Department of Environmental Quality. <a href="https://www.deq.nc.gov/about/divisions/air-quality/outreach-education-engagement/air-quality-science-and-data/emission-inventories/general-information-emission-inventories">https://www.deq.nc.gov/about/divisions/air-quality/outreach-education-engagement/air-quality-science-and-data/emission-inventories/general-information-emission-inventories</a>. Accessed on March 29, 2024.
\29\ Email from Eladio Knipping, Electric Power Research
Institute to Nick Hutson, Melanie King, and Greg Honda, EPA.
Subject: FW: Response to EPA Feedback on EPRI CT Reports. April 15,
2020. Docket ID No. EPA-HQ-OAR-2020-0408.
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In multiple instances, the petitioners' emission estimates were
based on permit limits or emission factors of other pollutants (VOC and
PM) that were then used to approximate the emissions of organic HAP
(e.g., formaldehyde) and metallic HAP (e.g., arsenic). This introduces
further uncertainty in the emission estimates for this source category.
Moreover, the petitioners stated in the petition that ``combustion
turbines' PM emissions are not a strong predictor of metallic HAP
emissions.'' Regarding arsenic, in the 2020 RTR, arsenic emissions were
one of the primary drivers for risk at sources firing distillate oil.
The petitioners stated that metallic HAP emissions from oil-fired
turbines are constituents of the fuel, and that the arsenic emissions
estimated by the EPA for the 2020 RTR were biased upward because
``regulations requiring lower sulfur content for diesel fuel have
resulted in lower arsenic content, if any, for these fuels, because the
techniques used to remove sulfur from fuels necessarily remove metals
such as arsenic also.'' One example of such regulation is the 15 parts
per million by weight (ppmw) sulfur standard for ultra-low sulfur
diesel fuel in 40 CFR 1090.305. The petitioners, however, did not
provide references supporting the statement that the arsenic content in
ultra-low sulfur diesel fuel is universally lower or documenting that
stationary combustion turbines in the source category are required to
use ultra-low sulfur diesel fuel. Rather, the new source performance
standards (NSPS) for stationary combustion turbines (units constructed,
modified, or reconstructed after February 18, 2005) require the use of
only fuel having a sulfur content that is equivalent to a sulfur
dioxide content less than 0.06 pounds per million British thermal units
(lb/MMBtu) (i.e., approximately 500 ppmw of sulfur content in
distillate fuel oil) for turbines located on the continent and 0.42 lb/
MMBtu (4,000 ppmw) for turbines in non-continental areas (71 FR 38497;
July
[[Page 26844]]
6, 2006 and 40 CFR part 60, NSPS subpart KKKK, at 40 CFR 60.4300).
Notably, permitted thresholds for stationary combustion turbines vary,
but the source identified to have the highest cancer risk in the 2020
RTR is permitted to combust diesel fuel with a sulfur content up to
1,500 ppmw (permit available in the docket to this rulemaking, Docket
ID No. EPA-HQ-OAR-2020-0408), which further demonstrates that there is
no assurance that turbines are using ultra-low sulfur diesel fuel.
The petitioners also provided summary fuel analysis reports from a
few stationary combustion turbines in the source category. In those
cases, fuel arsenic concentrations reported by the petitioners were
below the limit of detection of the instruments. The petitioners,
however, did not provide any information regarding the methods and
procedures that were used for the fuel sampling and the determination
of the detection limits for arsenic. Instead, results were only
indicated by a qualitative statement that the measurement was below the
limit of detection. Additionally, raw data were not provided. After
receipt of the first supplement to the petition, the EPA asked the
petitioners to provide more detail regarding the methods used for the
fuel measurements, including calibration data and information on the
determination of non-detects.\30\ The petitioners indicated that such
information would be provided, but the second supplement only included
more summary fuel sampling results and did not provide the more
detailed information requested by the EPA. Without this information,
the EPA cannot evaluate whether the quality of the data is adequate or
assess whether the detection limits are accurate and, therefore, cannot
determine whether the arsenic emissions estimated for these facilities
are representative of their actual emissions.
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\30\ Email from Eladio Knipping, Electric Power Research
Institute to Nick Hutson, Melanie King, and Greg Honda, EPA.
Subject: FW: Response to EPA Feedback on EPRI CT Reports. April 15,
2020. Docket ID No. EPA-HQ-OAR-2020-0408.
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2. The Measured Rates for Formaldehyde Emissions
Formaldehyde was the HAP emitted in the largest quantities from
stationary combustion turbines evaluated in the EPA's 2020 risk
analysis (see Table 3.1-1 of Risk Report). An examination of the
formaldehyde emission rates measured during the CAA section 114 testing
showed emissions that are significantly higher for some turbines than
those estimated in the petition analysis (as well as the 2020 RTR). For
instance, formaldehyde emissions at the two landfill gas-fired turbines
at the BMW Manufacturing facility averaged 0.28 lb/hour (for unit GT05)
and 0.65 lb/hour (for unit GT06) during the CAA section 114 testing.
Multiplying the hourly emission rate by the highest annual hours of
operation on 100 percent landfill gas for the turbines reported for the
CAA section 114 request, which occurred in the year 2016, yields annual
formaldehyde emissions of 0.80 tons/year for unit GT05 and 1.85 tons/
year for unit GT06. The formaldehyde emissions assumed for those units
in the petition analysis were 0.0096 tons/year for each turbine. The
measured emissions were 80 times higher than estimated for unit GT05
and 190 times higher than estimated for unit GT06. A similar analysis
of the formaldehyde emissions for units 7 and 8 at Northern Natural
Gas's Waterloo Compressor Station showed that the measured formaldehyde
emissions were 31 times (unit 7) and 18 times (unit 8) higher than the
estimated emissions.\31\ These differences in the measured formaldehyde
emissions versus the petitioners' estimated formaldehyde emissions
demonstrate that the petitioners' data are not adequate for purposes of
the Administrator's determination under CAA section 112(c)(9)(B).
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\31\ Comparison of estimated emissions in delisting petition
with actual measured emissions from CAA section 114 testing for BMW
Manufacturing and Waterloo Compressor Station. November 22, 2023.
Docket ID No. EPA-HQ-OAR-2020-0408. Note that the annual emissions
for the BMW Manufacturing turbines do not include emissions from the
additional hours that the turbines were operated on a blend of 80
percent landfill gas and 20 percent natural gas.
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These higher measured formaldehyde emissions may also indicate that
the EPA's finding in the 2020 RTR of a maximum individual lifetime
cancer risk for the Stationary Combustion Turbines source category of
3-in-1 million may be a significant underestimation. But the EPA has
also long acknowledged that the maximum individual lifetime cancer
risk, under CAA section 112(f)(2), ``does not necessarily reflect the
true risk, but [rather] displays a conservative risk level which is an
upper-bound that is unlikely to be exceeded.'' \32\ Moreover, as
previously explained, for delisting source categories that emit
carcinogenic HAP, CAA section 112(c)(9)(B)(i) sets a lifetime cancer
risk to the most exposed individual threshold of 1-in-1 million, which
differs significantly from the acceptable risk determination for
standards promulgated under CAA section 112(f)(2), where a lifetime
cancer risk to the most exposed individual of 100-in-1 million is
ordinarily the upper bound of acceptability. And, ultimately, sources
would remain subject to standards promulgated under CAA section
112(f)(2) in contrast to removal of all CAA section 112 regulatory
requirements if the EPA grants a delisting petition under CAA section
112(c)(9)(B).\33\
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\32\ 54 FR 38045.
\33\ The EPA readopted existing standards under CAA section
112(f)(2) (85 FR at 13530).
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3. Acute Multiplier
The acute multiplier used by the petitioners to assess the health
impacts from short-term exposures to HAP emissions for two facilities
is not adequately supported by the evidence. As discussed previously,
the risk analyses for both the 2020 RTR and the petition evaluated the
acute health risks posed by actual baseline emissions. To assess the
potential health impacts from short-term exposures, the petitioners
estimated worst-case 1-hour HAP emission rates (``acute emissions'')
from each turbine included in their analysis. For most sources, the
petitioners' analysis used an acute multiplier of 10 times the average
annual hourly emission rate for each turbine. Use of this value is
consistent with the acute multiplier used by the EPA in the 2020 RTR,
as discussed in the March 6, 2019, memorandum titled Review of the
Acute Multiplier Used to Derive Hourly Emission Rates for the
Stationary Combustion Turbines Risk Analysis that reviewed the acute
multiplier and that is available in the docket for the Stationary
Combustion Turbines RTR (Docket ID No. EPA-HQ-OAR-2017-0688-0070).
As discussed in the memorandum, the basis for the use of a default
acute multiplier of 10 in the 2020 RTR is a study of short-term
emissions variability in a heavily industrialized four-county area in
Texas.\34\ At the time of the RTR proposal, the EPA evaluated the
suitability of the default acute multiplier of 10 by reviewing
available stack test data for formaldehyde emissions from stationary
combustion turbines to determine the variability of hourly test runs.
To determine the emissions variability, the average formaldehyde
concentration for each unit was calculated using all available
[[Page 26845]]
valid stack test data for that unit, and then the concentration of
formaldehyde for each hourly test run was divided by that unit's
average to determine the run-to-average emissions ratio. The highest
run-to-average ratio in the EPA's analysis for the 2020 RTR was 6.7.
For two facilities, Salinas River Cogeneration and Sargent Canyon
Cogeneration, the petitioners stated that using the EPA's default ratio
of 10 in their analysis yielded acute hazard quotients exceeding 1. The
petitioners then used a value of 2 for the acute multiplier in their
analysis for those two facilities and justified this based on the ratio
of hours in the year to annual operating hours at those facilities,
rather than on information regarding worst-case emissions data. The
petitioners did not provide any information to show how a comparison of
the hours in the year to annual operating hours was relevant for an
analysis of potential worst-case 1-hour HAP emission rates or how a
multiplier of 2 was more valid than the multiplier used for the 2020
RTR, which was based on actual hourly emissions data. The EPA believes
that the petitioners' approach does not adequately account for spikes
in emissions and variability in emission rates at non-baseload
conditions (e.g., startup, part-load operation). At lower loads, more
incomplete combustion may occur and result in proportionately greater
organic HAP emissions. Furthermore, the oxidation catalysts used to
control organic HAP emissions for some turbines may not operate
effectively during startup until the catalyst reaches its appropriate
operating temperature.
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\34\ Allen, D., C. Murphy, Y. Kimura, W. Vizuete, and T. Edgar.
2004. Variable Industrial VOC Emissions and their impact on ozone
formation in the Houston Galveston Area. Final Report, Texas
Environmental Research Consortium Project H-13. April 16, 2004.
Docket ID No. EPA-HQ-OAR-2017-0688-0005.
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After receipt of the initial petition and the first supplement, the
EPA discussed these issues with the petitioners. The petitioners
indicated that they would provide an expanded justification for the use
of an acute multiplier of 2.\35\ The discussion of the acute multiplier
for Salinas River Cogeneration and Sargent Canyon Cogeneration in the
second supplement did not address the questions raised by the EPA.
Instead, it just restated the petitioners' previous justification for
using the ratio of hours in the year to annual operating hours.
Therefore, the petitioners have not adequately demonstrated that an
acute multiplier of 2 is appropriate for the turbines at the Salinas
River Cogeneration and Sargent Canyon Cogeneration facilities and,
therefore, that the hazard quotients for those two facilities are below
1.
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\35\ Email from Eladio Knipping, Electric Power Research
Institute to Nick Hutson, Melanie King, and Greg Honda, EPA.
Subject: FW: Response to EPA Feedback on EPRI CT Reports. April 15,
2020. Docket ID No. EPA-HQ-OAR-2020-0408.
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4. Accounting for Potential Increases in Emissions
As previously noted, emission estimates in the petition analyses
were primarily based on emission factors and historical fuel usage
data. For the purposes of determining whether the delisting criteria
under CAA section 112(c)(9)(B) are satisfied, risk evaluations must be
based on emission estimates that assume the controls required under CAA
section 112 are not in place unless they are also known to be required
under a different regulatory authority. This is because deleting a
source category from the list of major sources would result in removal
of the regulatory requirements specified in the applicable NESHAP.
However, the petitioners' emission estimates for those units with
oxidation catalyst were based on controlled emissions, and the
petitioners did not specify whether those oxidation catalysts were
installed to meet the Stationary Combustion Turbines NESHAP or to
satisfy regulatory requirements under other EPA programs (e.g., new
source review (NSR) or prevention of significant deterioration (PSD)
permits).\36\ As a result, the petitioners did not explain--and the EPA
was not able to determine based on the information submitted--whether
the emissions estimates and risk assessment presented by the
petitioners account for potential increases in emissions that might
result from delisting the Stationary Combustion Turbines source
category.
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\36\ As discussed previously, the EPA proposed to remove the
stay of the standards for new lean premix gas-fired and diffusion
flame gas-fired turbines on April 12, 2019 (84 FR 15046), prior to
the submittal of the petition to delist in August 2019. The EPA
finalized the removal of the stay on March 9, 2022 (87 FR 13183).
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D. HAP and Turbines Not Included in Petition
Regarding HAP emissions, in addition to the deficiencies discussed
in section IV.C., the emission estimates in the information submitted
by the petitioners do not include several HAP that have been
demonstrated to be emitted by stationary combustion turbines and do not
include one-fourth of the turbines in the source category. As discussed
in section III.C., the EPA required testing of stationary combustion
turbines to obtain data on emissions of formaldehyde, acid gases
(hydrogen fluoride and hydrogen chloride), and metallic HAP. The
emissions testing showed that there are measurable emissions of
metallic HAP from turbines operating on natural gas and landfill gas.
The risk analysis submitted by the petitioners did not include metallic
HAP emissions for natural gas and landfill gas turbines. Several
metallic HAP (arsenic, cadmium, lead, and mercury compounds) and acid
gases are included in both the EPA's health risk analysis and screening
for adverse environmental effects.
Regarding the universe of affected sources, the EPA has identified
an additional 245 turbines that are subject to the Stationary
Combustion Turbines NESHAP that were not included in the petitioners'
risk analyses. These additional turbines include units that are owned
and operated by companies that are members of the organizations that
submitted the petition to delist.\37\ The EPA has identified a total of
1,015 turbines that are subject to the NESHAP. Hence, the petitioners'
analyses do not account for nearly one-fourth of the turbines that are
subject to the Stationary Combustion Turbines NESHAP. This contrasts
with, for example, the delisting of the non-mercury cell chlorine
production subcategory where the EPA ``obtained chlorine and HCl
emission estimates from every known major source facility in the non-
mercury cell chlorine production subcategory using our authority under
section 114 of the CAA and conducted risk assessments for each
facility.'' \38\ As previously noted, a petitioner must provide a
detailed assessment of the available data concerning the potential
adverse human health and environmental effects and the potential for
human and environmental exposures from the source category that is to
be delisted. Such data must demonstrate that no source in the category
or subcategory emits HAP in quantities which may cause a lifetime risk
of cancer greater than 1-in-1 million to the individual in the
population who is most exposed to emissions of such pollutants from the
source or that no source in the category exceeds a level which is
adequate to protect public health with an ample margin of safety and no
adverse environmental effect will result from emissions from that
source category.
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\37\ Turbine NESHAP Unit List--Updated October 2023. Docket ID
No. EPA-HQ-OAR-2020-0408.
\38\ 68 FR 70951.
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V. What is the rationale for denying the petition?
The EPA is denying the petition because the EPA has determined that
the petition is incomplete. The petitioners did not address all the
necessary subject areas under CAA
[[Page 26846]]
section 112(c)(9)(B) and did not present adequate information and
analyses for the requested determination. As stated previously, CAA
section 112(c)(9)(B)(i) requires the EPA to determine that no source in
the category emits HAP in quantities which may cause a lifetime risk of
cancer greater than 1-in-1 million to the individual in the population
who is most exposed to emissions of such pollutants from the source.
Here, the petition and all the supplements to the petition did not
include HAP emissions measurements for all of the HAP emitted by the
Stationary Combustion Turbines source category.\39\ The risk analysis
submitted by the petitioners did not include metallic HAP emissions for
natural gas and landfill gas turbines, which the CAA section 114
information request results demonstrated are emitted from turbines
operating on both natural gas and landfill gas. Further, the
petitioners' analyses did not include nearly one-fourth of the
stationary combustion turbines that are subject to the Stationary
Combustion Turbines NESHAP. For the fuel sampling data and the acute
multiplier, the petitioners did not provide information requested by
the EPA that is necessary to evaluate the adequacy of the data. The EPA
also afforded petitioners opportunities to address the above referenced
identified gaps in the data and information underpinning their
petition, which petitioners declined. For these reasons, the EPA cannot
conclude that the petitioners have demonstrated that the maximum
individual lifetime cancer risk from all stationary combustion turbines
subject to CAA section 112 is less than the 1-in-1 million delisting
threshold under CAA section 112(c)(9)(B)(i).
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\39\ See, e.g., 66 FR at 21933, ``As the [Health Effects
Institute] Health Review Committee noted in its commentary, the
experiments in this study were `well designed and executed with
appropriate quality control and quality assurance procedures. Thus,
one can have confidence in the data.' '' (The EPA explaining and
agreeing with the use of certain health effect studies in the
delisting petition for Methanol).
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The EPA construes CAA section 112(c)(9)(B)(i) as calling for the
Administrator to make a determination that the criteria for delisting
are satisfied. Any such determination must be supported by measured
emissions data or otherwise reasonably account for operational
variability.\40\ This is because delisting of a source category would
result in the removal of applicable regulatory requirements under CAA
section 112 for such source category. The EPA cannot grant a petition
to delist a source category if there are major uncertainties that must
be addressed for the EPA to have sufficient information to make the
requisite substantive determination, under CAA section 112(c)(9)(B)(i).
And the burden remains on a petitioner to demonstrate that the
available data support an affirmative determination that HAP emissions
from a source category may not be reasonably anticipated to result in
adverse effects on human health or the environment. See American Forest
and Paper Ass'n v. EPA, 294 F.3d at 119 (``The statutory language
unambiguously places on a delisting petitioner the burden to make a
showing that there is adequate data about a substance to determine
exposure to it may not reasonably be anticipated to cause adverse
effects.'' (Emphasis in original; cleaned up)).
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\40\ ``Although public information indicated that over 140
million pounds of these substances are used annually in the U.S. and
that there is a general trend towards greater usage, the petitioner
did not provide measurements or estimates regarding the emissions
associated with such use. In the absence of such information, EPA
cannot make the substantive determination contemplated by CAA
Section 112(b)(3).'' 58 FR 4165 (The EPA explaining the decision to
deny the petition to delist five glycol ethers as a HAP for lack of
emission measurements and HAP estimated use).
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In addition to the incompleteness of the petition, the EPA's
technical review identified major uncertainties in the emission
estimates provided by the petitioners that are an additional and
separate independent basis for denial of the petition. The results of
the 2020 RTR risk analysis (based on actual emissions), under CAA
section 112(f)(2), indicated that the estimated maximum individual
lifetime cancer risk is 3-in-1 million. The petitioners' analyses
contained in their submittals claimed a maximum individual lifetime
cancer risk of 0.76-in-1 million as support for their petition to
delist under CAA section 112(c)(9). But the petitioners' analyses,
which included revised HAP emission estimates and a revised evaluation
of the 2020 RTR risk analysis, were primarily based on emission factors
and historical fuel usage data for a subset of the turbines that are
subject to CAA section 112.
The petitioners also did not include any stack testing on the
turbines that they analyzed to determine actual emissions. As stated
previously, emission factors do not provide sufficient certainty
regarding site-specific emissions that would provide confidence that no
source in the category exceeds the criteria for delisting. In addition,
the CAA section 114 emissions testing showed actual formaldehyde
emissions for some turbines that are significantly higher than those
estimated by the petitioners. Lastly, the petitioners did not explain
whether the emission estimates they relied on would continue to be
applicable if the EPA were to delist the source category. Overall, and
as shown in section IV., the petitioners did not provide sufficient
data or analyses for the purpose of estimating maximum offsite
pollutant concentrations that would enable the Administrator to make
the substantive determination contemplated by CAA section
112(c)(9)(B).\41\
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\41\ 58 FR 4165 (denying petition to delist five glycol ethers
as a HAP on similar grounds).
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The EPA has concluded that the available evidence is inadequate to
support a determination that no source in the Stationary Combustion
Turbines source category emits such HAP in quantities which may cause a
lifetime risk of cancer greater than 1-in-1 million to the individual
in the population who is most exposed to emissions of such pollutants
from the source category as called for under CAA section
112(c)(9)(B)(i). Because the petition is denied under CAA section
112(c)(9)(B)(i) for the reasons stated above, the EPA finds that it is
not necessary to make any determinations as to whether any source in
the category exceeds a level which is adequate to protect public health
with an ample margin of safety and presents adverse environmental
effects under CAA section 112(c)(9)(B)(ii).
For the reasons stated in this section, the EPA concludes that the
petitioners have not demonstrated that the Stationary Combustion
Turbines source category may be delisted under CAA section
112(c)(9)(B)(i). This means that the petitioners have failed to meet
the delisting criteria outlined in CAA section 112(c)(9)(B)(i), and the
EPA must deny the petition. Finally, because the EPA has determined
that the petitioners did not address all the necessary subject areas
under CAA section 112(c)(9)(B) and did not present adequate information
and analyses for each of the subject areas, the EPA is denying the
petition with prejudice. Any future petition to delist will be denied
as a matter of law unless such future petition is accompanied by
substantial new information or analysis.
Michael S. Regan,
Administrator.
[FR Doc. 2024-08004 Filed 4-15-24; 8:45 am]
BILLING CODE 6560-50-P
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