Proposed Rule2025-04906
Air Plan Approval; ID; Regional Haze Plan for the Second Implementation Period
Primary source
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Published
March 24, 2025
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is proposing to approve the Idaho regional haze State Implementation Plan (SIP) revision submitted on August 5, 2022, and supplemented on May 8, 2024. Idaho submitted the SIP revision to address the requirement to make reasonable progress toward the national goal of preventing any future, and remedying any existing, anthropogenic impairment of visibility in certain national parks and wilderness areas.
Full Text
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[Federal Register Volume 90, Number 55 (Monday, March 24, 2025)]
[Proposed Rules]
[Pages 13516-13549]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-04906]
[[Page 13515]]
Vol. 90
Monday,
No. 55
March 24, 2025
Part II
Environmental Protection Agency
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40 CFR Part 52
Air Plan Approval; ID; Regional Haze Plan for the Second Implementation
Period; Proposed Rule
Federal Register / Vol. 90, No. 55 / Monday, March 24, 2025 /
Proposed Rules
[[Page 13516]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R10-OAR 2024-0545; FRL-11879-01-R10]
Air Plan Approval; ID; Regional Haze Plan for the Second
Implementation Period
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve the Idaho regional haze State Implementation Plan (SIP)
revision submitted on August 5, 2022, and supplemented on May 8, 2024.
Idaho submitted the SIP revision to address the requirement to make
reasonable progress toward the national goal of preventing any future,
and remedying any existing, anthropogenic impairment of visibility in
certain national parks and wilderness areas.
DATES: Written comments must be received on or before April 23, 2025.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R10-
OAR-2024-0545 at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. For comments submitted at
<a href="http://regulations.gov">regulations.gov</a>, follow the online instructions for submitting
comments. Once submitted, comments may not be edited or removed from
<a href="http://regulations.gov">regulations.gov</a>. For either manner of submission, the EPA may publish
any comment received to its public docket. Do not submit electronically
any information you consider to be confidential business information or
other information the disclosure of which is restricted by statute.
Multimedia submissions (audio, video, etc.) must be accompanied by a
written comment. The written comment is considered the official comment
and should include discussion of all points you wish to make. The EPA
will generally not consider comments or comment contents located
outside of the primary submission (i.e., on the web, cloud, or other
file sharing system). For additional submission methods, please contact
the person identified in the FOR FURTHER INFORMATION CONTACT section.
For the full EPA public comment policy, information about confidential
business information or multimedia submissions, and general guidance on
making effective comments, please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>.
FOR FURTHER INFORMATION CONTACT: John Chi, EPA Region 10, 1200 Sixth
Avenue, Suite 155, Seattle, WA 98101, at (206) 553-1185 or
<a href="/cdn-cgi/l/email-protection#482b20216622272026082d3829662f273e"><span class="__cf_email__" data-cfemail="d0b3b8b9febabfb8be90b5a0b1feb7bfa6">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this document, the use of ``we''
and ``our'' means ``the EPA.''
Table of Contents
I. Background and Requirements for Regional Haze Plans
A. Regional Haze Background
B. Roles of Agencies in Addressing Regional Haze
II. Requirements for Regional Haze Plans for the Second
Implementation Period
A. Identification of Class I Areas
B. Calculations of Baseline, Current, and Natural Visibility
Conditions; Progress to Date; and the Uniform Rate of Progress
C. Long-Term Strategy for Regional Haze
D. Reasonable Progress Goals
E. Monitoring Strategy and Other State Implementation Plan
Requirements
F. Requirements for Periodic Reports Describing Progress Towards
the Reasonable Progress Goals
G. Requirements for State and Federal Land Manager Coordination
III. The EPA's Evaluation of the Idaho Regional Haze SIP Revision
for the Second Implementation Period
A. Background on the Idaho First Implementation Period SIP
Revision
B. The Idaho Second Implementation Period SIP Revision and the
EPA's Evaluation
C. Identification of Class I Areas
D. Calculations of Baseline, Current, and Natural Visibility
Conditions; Progress to Date; and the Uniform Rate of Progress
E. Long-Term Strategy for Regional Haze
F. Reasonable Progress Goals
G. Monitoring Strategy and Other Implementation Plan
Requirements
H. Requirements for Periodic Reports Describing Progress Towards
the Reasonable Progress Goals
I. Requirements for State and Federal Land Manager Coordination
IV. Proposed Action
V. Incorporation by Reference
VI. Statutory and Executive Order Reviews
I. Background and Requirements for Regional Haze Plans
A. Regional Haze Background
In the 1977 Clean Air Act Amendments, Congress created a program
\1\ to protect visibility in the nation's mandatory class I Federal
areas, which include certain national parks and wilderness areas.\2\
Congress established as a national goal the ``prevention of any future,
and the remedying of any existing, impairment of visibility in
mandatory class I Federal areas which impairment results from manmade
air pollution.'' \3\ Congress further directed the EPA to promulgate
regulations to assure reasonable progress toward meeting this national
goal.\4\
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\1\ Clean Air Act section 169A.
\2\ Areas statutorily designated as mandatory class I Federal
areas consist of national parks exceeding 6,000 acres, wilderness
areas and national memorial parks exceeding 5,000 acres, and all
international parks that were in existence on August 7, 1977. Clean
Air Act 162(a). There are 156 mandatory class I Federal areas. The
list of areas to which the visibility protection program applies is
set forth in 40 CFR part 81, subpart D.
\3\ Clean Air Act section 169A(a)(1).
\4\ Clean Air Act section 169A(a)(4).
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In 1990, Congress added section 169B to the Clean Air Act to
further address visibility impairment, specifically, impairment from
regional haze. The EPA subsequently promulgated the Regional Haze Rule
on July 1, 1999 (64 FR 35714), codified at 40 CFR 51.308.\5\ These
regional haze regulations are a central component of the EPA's
comprehensive visibility protection program for Class I areas.
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\5\ In addition to the generally applicable regional haze
provisions at 40 CFR 51.308, the EPA also promulgated regulations
specific to addressing regional haze visibility impairment in Class
I areas on the Colorado Plateau at 40 CFR 51.309. The latter
regulations are applicable only for specific jurisdictions' regional
haze plans submitted no later than December 17, 2007, and thus are
not relevant here.
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Regional haze is visibility impairment that is produced by a
multitude of anthropogenic sources and activities which are located
across a broad geographic area and that emit pollutants that impair
visibility. Visibility impairing pollutants include fine and coarse
particulate matter (PM) (e.g., sulfates, nitrates, organic carbon,
elemental carbon, and soil dust) and their precursors (e.g., sulfur
dioxide (SO<INF>2</INF>), nitrogen oxides (NO<INF>X</INF>), and, in
some cases, volatile organic compounds (VOC) and ammonia
(NH<INF>3</INF>)). Fine particle precursors react in the atmosphere to
form fine particulate matter (PM<INF>2.5</INF>), which impairs
visibility by scattering and absorbing light. Visibility impairment
reduces the perception of clarity and color, as well as visible
distance.\6\
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\6\ There are several ways to measure the amount of visibility
impairment, i.e., haze. One such measurement is the deciview, which
is the principal metric used by the Regional Haze Rule. Under many
circumstances, a change in one deciview will be perceived by the
human eye to be the same on both clear and hazy days. The deciview
is unitless. It is proportional to the logarithm of the atmospheric
extinction of light, which is the perceived dimming of light due to
its being scattered and absorbed as it passes through the
atmosphere. Atmospheric light extinction (b\ext\) is a metric used
to for expressing visibility and is measured in inverse megameters
(Mm<SUP>-1</SUP>).
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To address regional haze visibility impairment, the 1999 Regional
Haze Rule established an iterative planning process that requires both
States in which Class I areas are located and States ``the emissions
from which may reasonably be anticipated to cause or
[[Page 13517]]
contribute to any impairment of visibility'' in a Class I area to
periodically submit SIP revisions to address such impairment.\7\ Under
the Clean Air Act, each SIP revision must contain ``a long-term (ten to
fifteen years) strategy for making reasonable progress toward meeting
the national goal''.\8\ The initial round of SIP revisions also had to
address the statutory requirement that certain older, larger sources of
visibility impairing pollutants install and operate the best available
retrofit technology (BART).\9\ States' first regional haze SIPs were
due by December 17, 2007,\10\ with subsequent SIP revisions containing
updated long-term strategies originally due July 31, 2018, and every
ten years thereafter.\11\ The EPA established in the 1999 Regional Haze
Rule that all States either have Class I areas within their borders or
``contain sources whose emissions are reasonably anticipated to
contribute to regional haze in a Class I area''; therefore, all States
must submit regional haze SIPs.\12\
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\7\ Clean Air Act section 169A(b)(2). See also 40 CFR 51.308(b),
(f) (establishing submission dates for iterative regional haze SIP
revisions (64 FR 35714, July 1, 1999, at page 35768). The Regional
Haze Rule expresses the statutory requirement for states to submit
plans addressing out-of-state Class I areas by providing that states
must address visibility impairment ``in each mandatory Class I
Federal area located outside the State that may be affected by
emissions from within the State.'' 40 CFR 51.308(d), (f).
\8\ Clean Air Act section 169A(b)(2)(B).
\9\ Clean Air Act section 169A(b)(2)(A); 40 CFR 51.308(d), (e).
\10\ 40 CFR 51.308(b).
\11\ 64 FR 35714, July 1, 1999, at page 35768.
\12\ 64 FR 35714, July 1, 1999, at page 35721. In addition to
each of the fifty states, the EPA also concluded that the Virgin
Islands and District of Columbia must also submit regional haze SIPs
because they either contain a Class I area or contain sources whose
emissions are reasonably anticipated to contribute regional haze in
a Class I area. See 40 CFR 51.300(b), (d)(3).
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Much of the focus in the first implementation period of the
regional haze program, which ran from 2007 through 2018, was on
satisfying States' BART obligations. First implementation period SIPs
were additionally required to contain long-term strategies for making
reasonable progress toward the national visibility goal, of which BART
is one component. The core required elements for the first
implementation period SIPs (other than BART) are laid out in 40 CFR
51.308(d).
On January 10, 2017, the EPA promulgated revisions to the Regional
Haze Rule that apply for the second and subsequent implementation
periods (82 FR 3078). The 2017 rulemaking made several changes to the
requirements for regional haze SIPs to clarify States' obligations and
streamline certain regional haze requirements. The revisions to the
regional haze program for the second and subsequent implementation
periods focused on the requirement that SIPs contain long-term
strategies for making reasonable progress towards the national
visibility goal. The reasonable progress requirements as revised in the
2017 rulemaking (referred to here as the 2017 Regional Haze Rule
Revisions) are codified at 40 CFR 51.308(f). Among other changes, the
2017 Regional Haze Rule Revisions adjusted the deadline for States to
submit their second implementation period SIPs from July 31, 2018, to
July 31, 2021, clarified the order of analysis and the relationship
between RPGs and the long-term strategy, and focused on making
visibility improvements on the days with the most anthropogenic
visibility impairment, as opposed to the days with the most visibility
impairment overall. The EPA also revised requirements of the visibility
protection program related to periodic progress reports and Federal
Land Manager consultation. The specific requirements applicable to
second implementation period regional haze SIP revisions are addressed
in detail in the following paragraphs.
B. Roles of Agencies in Addressing Regional Haze
Because the air pollutants and pollution affecting visibility in
Class I areas can be transported over long distances, successful
implementation of the regional haze program requires long-term,
regional coordination among multiple jurisdictions and agencies that
have responsibility for Class I areas and the emissions that impact
visibility in those areas. In order to address regional haze, States
need to develop strategies in coordination with one another,
considering the effect of emissions from one jurisdiction on the air
quality in another. Five regional planning organizations (RPOs),\13\
which include representation from State and tribal governments, the
EPA, and Federal Land Managers, were developed in the lead-up to the
first implementation period to address regional haze. Regional planning
organizations evaluate technical information to better understand how
emissions impact Class I areas across the country, pursue the
development of regional strategies to reduce emissions of particulate
matter and other pollutants leading to regional haze, and help States
meet the consultation requirements of the Regional Haze Rule.
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\13\ RPOs are sometimes also referred to as ``multi-
jurisdictional organizations,'' or MJOs. For the purposes of this
notice, the terms RPO and MJO are synonymous.
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1. The Western Regional Air Partnership
The Western Regional Air Partnership (WRAP) \14\ is one of five
regional air quality planning organizations across the United
States.\15\ The WRAP functions as a voluntary partnership of State,
tribal, Federal, and local air agencies whose purpose is to understand
current and evolving regional air quality issues in the west. There are
15 member States in the WRAP, including Idaho, in addition to 28 Tribes
and 30 Local air agency members.\16\ The WRAP Federal partners include
the EPA, National Park Service, Fish and Wildlife Service, Forest
Service, and Bureau of Land Management.
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\14\ The WRAP website may be found at <a href="https://www.wrapair2.org/">https://www.wrapair2.org/</a>.
\15\ See <a href="https://www.epa.gov/visibility/visibility-regional-planning-organizations/">https://www.epa.gov/visibility/visibility-regional-planning-organizations/</a> for information about the regional planning
organizations, or RPOs, for visibility.
\16\ The WRAP membership list may be found at <a href="https://www.wrapair2.org/membership.aspx/">https://www.wrapair2.org/membership.aspx/</a>.
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Based on emissions and monitoring data supplied by its membership,
the WRAP produced technical tools to support regional modeling of
visibility impacts at Class I areas across the west.\17\ The ``WRAP
Technical Support System'' consolidated air quality monitoring data,
meteorological and receptor modeling data analyses, emissions
inventories and projections, and gridded air quality/visibility
regional modeling results. The WRAP Technical Support System is
accessible by members and allows for the creation of maps, figures, and
tables to export and use in developing regional haze SIP revisions, and
maintains the original source data for verification and further
analysis.
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\17\ Technical information may be found at <a href="https://www.wrapair2.org/RHPWG.aspx/">https://www.wrapair2.org/RHPWG.aspx/</a> and in the docket for this action.
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II. Requirements for Regional Haze Plans for the Second Implementation
Period
Under the Clean Air Act and the EPA's regulations, all 50 States,
the District of Columbia, and the United States (U.S.) Virgin Islands
are required to submit regional haze SIPs satisfying the applicable
requirements for the second implementation period of the regional haze
program by July 31, 2021. Each State's SIP must contain a long-term
strategy for making reasonable progress toward meeting the national
goal of remedying any existing and preventing any future anthropogenic
[[Page 13518]]
visibility impairment in Class I areas.\18\ To this end, 40 CFR
51.308(f) lays out the process by which States determine what
constitutes their long-term strategies, with the order of the
requirements in section 51.308(f)(1) through (3) generally mirroring
the order of the steps in the reasonable progress analysis \19\ and
(f)(4) through (6) containing additional, related requirements.
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\18\ Clean Air Act section 169A(b)(2)(B).
\19\ The EPA explained in the 2017 Regional Haze Rule Revisions
that we were adopting new regulatory language in 40 CFR 51.308(f)
that, unlike the structure in 51.308(d), ``tracked the actual
planning sequence.'' (82 FR 3091, January 10, 2017).
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Broadly speaking, a State first must identify the Class I areas
within the State and determine the Class I areas outside the State in
which visibility may be affected by emissions from the State. These are
the Class I areas that must be addressed in the State's long-term
strategy.\20\ For each Class I area within its borders, a State must
then calculate the baseline (five-year average period of 2000-2004),
current, and natural visibility conditions (i.e., visibility conditions
without anthropogenic visibility impairment) for that area, as well as
the visibility improvement made to date and the ``uniform rate of
progress'' (URP). The URP is the linear rate of progress needed to
attain natural visibility conditions, assuming a starting point of
baseline visibility conditions in 2004 and ending with natural
conditions in 2064. This linear interpolation is used as a tracking
metric to help states assess the amount of progress they are making
towards the national visibility goal over time in each Class I
area.\21\ Each State having a Class I area and/or emissions that may
affect visibility in a Class I area must then develop a long-term
strategy that includes the enforceable emission limitations, compliance
schedules, and other measures that are necessary to make reasonable
progress in such areas. A reasonable progress determination is based on
applying the four factors in Clean Air Act section 169A(g)(1) to
sources of visibility-impairing pollutants that the State has selected
to assess for controls for the second implementation period.\22\
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\20\ 40 CFR 51.308(f), (f)(2).
\21\ 40 CFR 51.308(f)(1).
\22\ 40 CFR 51.308(f)(2).
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Additionally, as further explained below, the Regional Haze Rule at
40 CFR 51.308(f)(2)(iv) separately provides five ``additional factors''
\23\ that States must consider in developing their long-term
strategies. A State evaluates potential emission reduction measures for
those selected sources and determines which are necessary to make
reasonable progress. Those measures are then incorporated into the
State's long-term strategy. After a State has developed its long-term
strategy, it then establishes RPGs for each Class I area within its
borders by modeling the visibility impacts of all reasonable progress
controls at the end of the second implementation period, i.e., in 2028,
as well as the impacts of other requirements of the Clean Air Act. The
RPGs include reasonable progress controls not only for sources in the
State in which the Class I area is located, but also for sources in
other States that contribute to visibility impairment in that area. The
RPGs are then compared to the baseline visibility conditions and the
uniform rate of progress to ensure that progress is being made towards
the statutory goal of preventing any future and remedying any existing
anthropogenic visibility impairment in Class I areas.\24\
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\23\ The five ``additional factors'' for consideration in 40 CFR
51.308(f)(2)(iv) are distinct from the four factors listed in Clean
Air Act section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that States
must consider and apply to sources in determining reasonable
progress.
\24\ 40 CFR 51.308(f)(2)-(3).
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In addition to satisfying the requirements at 40 CFR 51.308(f)
related to reasonable progress, the regional haze SIP revisions for the
second implementation period must address the requirements in section
51.308(g)(1) through (5) pertaining to periodic reports describing
progress towards the RPGs, 40 CFR 51.308(f)(5), as well as requirements
for Federal Land Manager consultation that apply to all visibility
protection SIPs and SIP revisions.\25\
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\25\ 40 CFR 51.308(i).
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A State must submit its regional haze SIP and subsequent SIP
revisions to the EPA according to the requirements applicable to all
SIP revisions under the Clean Air Act and the EPA's regulations.\26\
Upon EPA approval, a SIP is enforceable by the EPA and the public under
the Clean Air Act. If the EPA finds that a State fails to make a
required SIP revision, or if the EPA finds that a SIP is incomplete or
disapproves the SIP, the EPA must promulgate a Federal implementation
plan (FIP) that satisfies the applicable requirements.\27\
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\26\ See Clean Air Act section 169(b)(2); Clean Air Act section
110(a).
\27\ Clean Air Act section 110(c)(1).
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A. Identification of Class I Areas
The first step in developing a regional haze SIP is for a State to
determine which Class I areas, in addition to those within its borders,
``may be affected'' by emissions from within the State. In the 1999
Regional Haze Rule, the EPA determined that all States contribute to
visibility impairment in at least one Class I area and explained that
the statute and regulations lay out an ``extremely low triggering
threshold'' for determining ``whether States should be required to
engage in air quality planning and analysis as a prerequisite to
determining the need for control of emissions from sources within their
State.'' \28\
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\28\ 64 FR 35714, July 1, 1999, at pages 35720-35722.
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A State must determine which Class I areas must be addressed by its
SIP by evaluating the total emissions of visibility impairing
pollutants from all sources within the State. The determination of
which Class I areas may be affected by a State's emissions is subject
to the requirement in 40 CFR 51.308(f)(2)(iii) to ``document the
technical basis, including modeling, monitoring, cost, engineering, and
emissions information, on which the State is relying to determine the
emission reduction measures that are necessary to make reasonable
progress in each mandatory Class I Federal area it affects.''
B. Calculations of Baseline, Current, and Natural Visibility
Conditions; Progress to Date; and the Uniform Rate of Progress
As part of assessing whether a SIP revision for the second
implementation period is providing for reasonable progress towards the
national visibility goal, the Regional Haze Rule contains requirements
in section 51.308(f)(1) related to tracking visibility improvement over
time. The requirements of this section apply only to States having
Class I areas within their borders; the required calculations must be
made for each such Class I area. The EPA's 2018 Visibility Tracking
Guidance \29\ provides recommendations to assist States in satisfying
their obligations under section 51.308(f)(1); specifically, in
developing information on baseline, current, and natural visibility
conditions, and in making optional adjustments to the uniform rate of
progress to account for the impacts of international anthropogenic
emissions and prescribed fires.\30\
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\29\ The 2018 Visibility Tracking Guidance references and relies
on parts of the 2003 Tracking Guidance: ``Guidance for Tracking
Progress Under the Regional Haze Rule,'' which can be found at
<a href="https://www.epa.gov/sites/default/files/2021-03/documents/tracking.pdf">https://www.epa.gov/sites/default/files/2021-03/documents/tracking.pdf</a> and in the docket for this action.
\30\ 82 FR 3078, January 10, 2017, at pages 3103-05.
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[[Page 13519]]
The Regional Haze Rule requires tracking of visibility conditions
on two sets of days: the clearest and the most impaired days.
Visibility conditions for both sets of days are expressed as the
average deciview index for the relevant five-year period (the period
representing baseline or current visibility conditions). The Regional
Haze Rule provides that the relevant sets of days for visibility
tracking purposes are the 20% clearest (the 20% of monitored days in a
calendar year with the lowest values of the deciview index) and 20%
most impaired days (the 20% of monitored days in a calendar year with
the highest amounts of anthropogenic visibility impairment).\31\ A
State must calculate visibility conditions for both the 20% clearest
and 20% most impaired days for the baseline period of 2000-2004 and the
most recent five-year period for which visibility monitoring data are
available (representing current visibility conditions).\32\ States must
also calculate natural visibility conditions for the clearest and most
impaired days \33\ by estimating the conditions that would exist on
those two sets of days absent anthropogenic visibility impairment.\34\
Using all these data, States must then calculate, for each Class I
area, the amount of progress made since the baseline period (2000-2004)
and how much improvement is left to achieve in order to reach natural
visibility conditions.
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\31\ 40 CFR 51.301. This notice also refers to the 20% clearest
and 20% most anthropogenically impaired days as the ``clearest'' and
``most impaired'' or ``most anthropogenically impaired'' days,
respectively.
\32\ 40 CFR 51.308(f)(1)(i), (iii).
\33\ The Regional Haze Rule at 40 CFR 51.308(f)(1)(ii) contains
an error related to the requirement for calculating two sets of
natural conditions values. The rule says, ``most impaired days or
the clearest days'' where it should say ``most impaired days and
clearest days.'' This is an error that was intended to be corrected
in the 2017 Regional Haze Rule Revisions but did not get corrected
in the final rule language. This is supported by the preamble text
on page 3098 in the document published at 82 FR 3078, January 10,
2017: ``In the final version of 40 CFR 51.308(f)(1)(ii), an
occurrence of ``or'' has been corrected to ``and'' to indicate that
natural visibility conditions for both the most impaired days and
the clearest days must be based on available monitoring
information.''
\34\ 40 CFR 51.308(f)(1)(ii).
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Using the data for the set of most impaired days only, States must
plot a line between visibility conditions in the baseline period and
natural visibility conditions for each Class I area to determine the
uniform rate of progress--the amount of visibility improvement,
measured in deciviews, that would need to be achieved during each
implementation period in order to achieve natural visibility conditions
by the end of 2064. The uniform rate of progress is used in later steps
of the reasonable progress analysis for informational purposes and to
provide a non-enforceable benchmark against which to assess a Class I
area's rate of visibility improvement. Additionally, in the 2017
Regional Haze Rule Revisions, the EPA provided States the option of
proposing to adjust the endpoint of the uniform rate of progress to
account for impacts of anthropogenic sources outside the U.S. and/or
impacts of certain types of wildland prescribed fires. These
adjustments, which must be approved by the EPA, are intended to avoid
any perception that States should compensate for impacts from
international anthropogenic sources and to give States the flexibility
to determine that limiting the use of wildland-prescribed fire is not
necessary for reasonable progress.\35\
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\35\ 82 FR 3078, January 10, 2017, at page 3107, footnote 116.
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The EPA's 2018 Visibility Tracking Guidance can be used to help
satisfy the 40 CFR 51.308(f)(1) requirements, including in developing
information on baseline, current, and natural visibility conditions,
and in making optional adjustments to the uniform rate of progress. In
addition, the 2020 Data Completeness Memo provides recommendations on
the data completeness language referenced in section 51.308(f)(1)(i)
and provides updated natural conditions estimates for each Class I
area.
C. Long-Term Strategy for Regional Haze
The core component of a regional haze SIP revision is a long-term
strategy that addresses regional haze in each Class I area within a
State's borders and each Class I area that may be affected by emissions
from the State. The long-term strategy ``must include the enforceable
emissions limitations, compliance schedules, and other measures that
are necessary to make reasonable progress, as determined pursuant to
(f)(2)(i) through (iv).'' \36\ The amount of progress that is
``reasonable progress'' is based on applying the four statutory factors
in Clean Air Act section 169A(g)(1) in an evaluation of potential
control options for sources of visibility impairing pollutants, which
is referred to as a ``four-factor'' analysis. The outcome of that
analysis is the emission reduction measures that a particular source or
group of sources needs to implement in order to make reasonable
progress towards the national visibility goal.\37\ Emission reduction
measures that are necessary to make reasonable progress may be either
new, additional control measures for a source, or they may be the
existing emission reduction measures that a source is already
implementing. See 82 FR 3078, January 10, 2017, at pages 3092-93. Such
measures must be represented by ``enforceable emissions limitations,
compliance schedules, and other measures'' (i.e., any additional
compliance tools) in a State's long-term strategy in its SIP.\38\
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\36\ 40 CFR 51.308(f)(2).
\37\ 40 CFR 51.308(f)(2)(i).
\38\ 40 CFR 51.308(f)(2).
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Section 51.308(f)(2)(i) provides the requirements for the four-
factor analysis. The first step of this analysis entails selecting the
sources to be evaluated for emission reduction measures; to this end,
States should consider ``major and minor stationary sources or groups
of sources, mobile sources, and area sources'' of visibility impairing
pollutants for potential four-factor control analysis.\39\ A threshold
question at this step is which visibility impairing pollutants will be
analyzed.
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\39\ 40 CFR 51.308(f)(2)(ii).
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While States have discretion to choose any source selection
methodology that is reasonable, whatever choices they make should be
reasonably explained. To this end, 40 CFR 51.308(f)(2)(i) requires that
a State's SIP revision include ``a description of the criteria it used
to determine which sources or groups of sources it evaluated.'' The
technical basis for source selection, which may include methods for
quantifying potential visibility impacts such as emissions divided by
distance metrics, trajectory analyses, residence time analyses, and/or
photochemical modeling, must also be appropriately documented, as
required by 40 CFR 51.308(f)(2)(iii).
Once a State has selected the set of sources, the next step is to
determine the emissions reduction measures for those sources that are
necessary to make reasonable progress for the second implementation
period.\40\ This is accomplished by considering the four factors--``the
costs of compliance, the time necessary for compliance, and the energy
and nonair quality environmental impacts of compliance, and the
remaining useful life of any
[[Page 13520]]
existing source subject to such requirements.'' \41\ The EPA has
explained that the four-factor analysis is an assessment of potential
emission reduction measures (i.e., control options) for sources; ``use
of the terms `compliance' and `subject to such requirements' in section
169A(g)(1) strongly indicates that Congress intended the relevant
determination to be the requirements with which sources would have to
comply in order to satisfy the [Clean Air Act's] reasonable progress
mandate.'' \42\ Thus, for each source it has selected for four-factor
analysis,\43\ a State should consider a ``meaningful set'' of
technically feasible control options for reducing emissions of
visibility impairing pollutants.\44\
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\40\ The Clean Air Act provides that, ``[i]n determining
reasonable progress there shall be taken into consideration'' the
four statutory factors. Clean Air Act section 169A(g)(1). However,
in addition to four-factor analyses for selected sources, groups of
sources, or source categories, a state may also consider additional
emission reduction measures for inclusion in its long-term strategy,
e.g., from other newly adopted, on-the-books, or on-the-way rules
and measures for sources not selected for four-factor analysis for
the second implementation period.
\41\ Clean Air Act 169A(g)(1).
\42\ 82 FR 3078, January 10, 2017, at page 3091.
\43\ ``Each source'' or ``particular source'' is used here as
shorthand. While a source-specific analysis is one way of applying
the four factors, neither the statute nor the Regional Haze Rule
requires states to evaluate individual sources. Rather, states have
``the flexibility to conduct four-factor analyses for specific
sources, groups of sources or even entire source categories,
depending on state policy preferences and the specific circumstances
of each state.'' 82 FR 3078, January 10, 2017, at page 3088.
However, not all approaches to grouping sources for four-factor
analysis are necessarily reasonable; the reasonableness of grouping
sources in any particular instance will depend on the circumstances
and the manner in which grouping is conducted. If it is feasible to
establish and enforce different requirements for sources or
subgroups of sources, and if relevant factors can be quantified for
those sources or subgroups, then states should make a separate
reasonable progress determination for each source or subgroup. 2021
Clarifications Memo at pages 7-8.
\44\ 82 FR 3078, January 10, 2017, at page 3088.
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After identifying a reasonable set of potential control options for
the sources it has selected, a State then collects information on the
four factors with regard to each option identified. The EPA has also
explained that, in addition to the four statutory factors, States have
flexibility under the Clean Air Act and Regional Haze Rule to
reasonably consider visibility benefits as an additional factor
alongside the four statutory factors.\45\ Ultimately, while States have
discretion to reasonably weigh the factors and to determine what level
of control is needed, section 51.308(f)(2)(i) provides that a State
``must include in its implementation plan a description of . . . how
the four factors were taken into consideration in selecting the measure
for inclusion in its long-term strategy.''
---------------------------------------------------------------------------
\45\ See, e.g., Responses to Comments on Protection of
Visibility: Amendments to Requirements for State Plans; Proposed
Rule (81 FR 26942, May 4, 2016) (December 2016), Docket Number EPA-
HQ-OAR-2015-0531, U.S. Environmental Protection Agency at page 186;
EPA 2019 Guidance at pages 36-37.
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As explained above, section 51.308(f)(2)(i) requires States to
determine the emission reduction measures for sources that are
necessary to make reasonable progress by considering the four factors.
Pursuant to section 51.308(f)(2), measures that are necessary to make
reasonable progress towards the national visibility goal must be
included in a State's long-term strategy and in its SIP.\46\ If the
outcome of a four-factor analysis is that an emissions reduction
measure is necessary to make reasonable progress towards remedying
anthropogenic visibility impairment, that measure must be included in
the SIP.
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\46\ States may choose to, but are not required to, include
measures in their long-term strategies beyond just the emission
reduction measures that are necessary for reasonable progress. See
2021 Clarifications Memo at 16. For example, states with smoke
management programs may choose to submit their smoke management
plans to the EPA for inclusion in their SIPs but are not required to
do so. See, e.g., 82 FR 3078, January 10, 2017, at pages 3108-3109,
(requirement to consider smoke management practices and smoke
management programs under 40 CFR 51.308(f)(2)(iv) does not require
states to adopt such practices or programs into their SIPs, although
they may elect to do so).
---------------------------------------------------------------------------
As with source selection, the characterization of information on
each of the factors is also subject to the documentation requirement in
section 51.308(f)(2)(iii). The reasonable progress analysis, including
source selection, information gathering, characterization of the four
statutory factors (and potentially visibility), balancing of the four
factors, and selection of the emission reduction measures that
represent reasonable progress, is a technically complex exercise, but
also a flexible one that provides States with bounded discretion to
design and implement approaches appropriate to their circumstances.
Given this flexibility, section 51.308(f)(2)(iii) plays an important
function in requiring a State to document the technical basis for its
decision making so that the public and the EPA can comprehend and
evaluate the information and analysis the State relied upon to
determine what emission reduction measures must be in place to make
reasonable progress. The technical documentation must include the
modeling, monitoring, cost, engineering, and emissions information on
which the State relied to determine the measures necessary to make
reasonable progress. This documentation requirement can be met through
the provision of and reliance on technical analyses developed through a
regional planning process, so long as that process and its output has
been approved by all State participants. In addition to the explicit
regulatory requirement to document the technical basis of their
reasonable progress determinations, States are also subject to the
general principle that those determinations must be reasonably moored
to the statute.\47\ That is, a State's decisions about the emission
reduction measures that are necessary to make reasonable progress must
be consistent with the statutory goal of remedying existing and
preventing future visibility impairment.
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\47\ See Arizona ex rel. Darwin v. U.S. EPA, 815 F.3d 519, 531
(9th Cir. 2016); Nebraska v. U.S. EPA, 812 F.3d 662, 668 (8th Cir.
2016); North Dakota v. EPA, 730 F.3d 750, 761 (8th Cir. 2013);
Oklahoma v. EPA, 723 F.3d 1201, 1206, 1208-10 (10th Cir. 2013); cf.
also National Parks Conservation Association v. EPA, 803 F.3d 151,
165 (3d Cir. 2015); Alaska Department of Environmental Conservation
v. EPA, 540 U.S. 461, 485, 490 (2004).
---------------------------------------------------------------------------
The four statutory factors (and potentially visibility) are used to
determine what emission reduction measures for selected sources must be
included in a State's long-term strategy for making reasonable
progress. Additionally, the Regional Haze Rule at 40 CFR
51.308(f)(2)(iv) separately provides five ``additional factors'' \48\
that States must consider in developing their long-term strategies: (1)
Emission reductions due to ongoing air pollution control programs,
including measures to address reasonably attributable visibility
impairment; (2) measures to reduce the impacts of construction
activities; (3) source retirement and replacement schedules; (4) basic
smoke management practices for prescribed fire used for agricultural
and wildland vegetation management purposes and smoke management
programs; and (5) the anticipated net effect on visibility due to
projected changes in point, area, and mobile source emissions over the
period addressed by the long-term strategy.
---------------------------------------------------------------------------
\48\ The five ``additional factors'' for consideration in
section 51.308(f)(2)(iv) are distinct from the four factors listed
in Clean Air Act section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that
states must consider and apply to sources in determining reasonable
progress.
---------------------------------------------------------------------------
Because the air pollution that causes regional haze crosses State
boundaries, section 51.308(f)(2)(ii) requires a State to consult with
other States that also have emissions that are reasonably anticipated
to contribute to visibility impairment in a given Class I area.
Consultation allows for each State that impacts visibility in an area
to share whatever technical information, analyses, and control
determinations may be necessary to develop coordinated emission
management strategies. This coordination may be managed through inter-
and intra-regional planning organization consultation and the
development of regional emissions strategies; additional consultations
between States outside of
[[Page 13521]]
regional planning organization processes may also occur. If a State,
pursuant to consultation, agrees that certain measures (e.g., a certain
emission limitation) are necessary to make reasonable progress at a
Class I area, it must include those measures in its SIP.\49\
Additionally, the Regional Haze Rule requires that States that
contribute to visibility impairment at the same Class I area consider
the emission reduction measures the other contributing States have
identified as being necessary to make reasonable progress for their own
sources.\50\ If a State has been asked to consider or adopt certain
emission reduction measures, but ultimately determines those measures
are not necessary to make reasonable progress, that State must document
in its SIP the actions taken to resolve the disagreement.\51\ The EPA
will consider the technical information and explanations presented by
the submitting State and the State with which it disagrees when
considering whether to approve the SIP revision. Under all
circumstances, a State must document in its SIP revision all
substantive consultations with other contributing States.\52\
---------------------------------------------------------------------------
\49\ 40 CFR 51.308(f)(2)(ii)(A).
\50\ 40 CFR 51.308(f)(2)(ii)(B).
\51\ 40 CFR 51.308(f)(2)(ii)(C).
\52\ 40 CFR 51.308(f)(2)(ii)(C).
---------------------------------------------------------------------------
D. Reasonable Progress Goals
Reasonable progress goals (RPGs) ``measure the progress that is
projected to be achieved by the control measures States have determined
are necessary to make reasonable progress based on a four-factor
analysis.'' \53\ Their primary purpose is to assist the public and the
EPA in assessing the reasonableness of States' long-term strategies for
making reasonable progress towards the national visibility goal.\54\
States in which Class I areas are located must establish two RPGs, both
in deciviews--one representing visibility conditions on the clearest
days and one representing visibility on the most anthropogenically
impaired days--for each area within their borders.\55\ The two RPGs are
intended to reflect the projected impacts, on the two sets of days, of
the emission reduction measures the State with the Class I area, as
well as all other contributing States, have included in their long-term
strategies for the second implementation period. The RPGs also account
for the projected impacts of implementing other Clean Air Act
requirements, including non-SIP based requirements. Because RPGs are
the modeled result of the measures in States' long-term strategies (as
well as other measures required under the Clean Air Act), they cannot
be determined before States have conducted their four-factor analyses
and determined the control measures that are necessary to make
reasonable progress.\56\
---------------------------------------------------------------------------
\53\ 82 FR 3078, January 10, 2017, at page 3091.
\54\ 40 CFR 51.308(f)(3)(iii)-(iv).
\55\ 40 CFR 51.308(f)(3)(i).
\56\ 82 FR 3078, January 10, 2017, at page 3092.
---------------------------------------------------------------------------
For the second implementation period, the RPGs are set for 2028.
RPGs are not enforceable targets, 40 CFR 51.308(f)(3)(iii). While
States are not legally obligated to achieve the visibility conditions
described in their RPGs, section 51.308(f)(3)(i) requires that ``[t]he
long-term strategy and the reasonable progress goals must provide for
an improvement in visibility for the most impaired days since the
baseline period and ensure no degradation in visibility for the
clearest days since the baseline period.'' Thus, States are required to
have emission reduction measures in their long-term strategies that are
projected to achieve visibility conditions on the most impaired days
that are better than the baseline period and shows no degradation on
the clearest days compared to the clearest days from the baseline
period. The baseline period for the purpose of this comparison is the
baseline visibility condition--the annual average visibility condition
for the period 2000-2004.\57\
---------------------------------------------------------------------------
\57\ 40 CFR 51.308(f)(1)(i); 82 FR 2078, January 10, 2017, at
pages 3097-98.
---------------------------------------------------------------------------
So that RPGs may also serve as a metric for assessing the amount of
progress a State is making towards the national visibility goal, the
Regional Haze Rule requires States with Class I areas to compare the
2028 RPG for the most impaired days to the corresponding point on the
uniform rate of progress line (representing visibility conditions in
2028 if visibility were to improve at a linear rate from conditions in
the baseline period of 2000-2004 to natural visibility conditions in
2064). If the most impaired days RPG in 2028 is above the uniform rate
of progress (i.e., if visibility conditions are improving more slowly
than the rate described by the uniform rate of progress), each State
that contributes to visibility impairment in the Class I area must
demonstrate, based on the four-factor analysis required under 40 CFR
51.308(f)(2)(i), that no additional emission reduction measures would
be reasonable to include in its long-term strategy.\58\ To this end, 40
CFR 51.308(f)(3)(ii) requires that each State contributing to
visibility impairment in a Class I area that is projected to improve
more slowly than the uniform rate of progress provide ``a robust
demonstration, including documenting the criteria used to determine
which sources or groups [of] sources were evaluated and how the four
factors required by paragraph (f)(2)(i) were taken into consideration
in selecting the measures for inclusion in its long-term strategy.''
---------------------------------------------------------------------------
\58\ 40 CFR 51.308(f)(3)(ii).
---------------------------------------------------------------------------
E. Monitoring Strategy and Other State Implementation Plan Requirements
Section 51.308(f)(6) requires States to have certain strategies and
elements in place for assessing and reporting on visibility. Individual
requirements under this subsection apply either to States with Class I
areas within their borders, States with no Class I areas but that are
reasonably anticipated to cause or contribute to visibility impairment
in any Class I area, or both. A State with Class I areas within its
borders must submit with its SIP revision a monitoring strategy for
measuring, characterizing, and reporting regional haze visibility
impairment that is representative of all Class I areas within the
State. SIP revisions for such States must also provide for the
establishment of any additional monitoring sites or equipment needed to
assess visibility conditions in Class I areas, as well as reporting of
all visibility monitoring data to the EPA at least annually. Compliance
with the monitoring strategy requirement may be met through a State's
participation in the Interagency Monitoring of Protected Visual
Environments (IMPROVE) monitoring network, which is used to measure
visibility impairment caused by air pollution at the 156 Class I areas
covered by the visibility program.\59\ The IMPROVE monitoring data is
used to determine the 20% most anthropogenically impaired and 20%
clearest sets of days every year at each Class I area and tracks
visibility impairment over time.
---------------------------------------------------------------------------
\59\ 40 CFR 51.308(f)(6), (f)(6)(i), (f)(6)(iv).
---------------------------------------------------------------------------
All States' SIPs must provide for procedures by which monitoring
data and other information are used to determine the contribution of
emissions from within the State to regional haze visibility impairment
in affected Class I areas.\60\ Section 51.308(f)(6)(v) further requires
that all States' SIPs provide for a Statewide inventory of emissions of
pollutants that are reasonably anticipated to cause or contribute to
visibility impairment in any Class I area; the inventory must include
emissions for the most recent year for which data are available and
estimates of future
[[Page 13522]]
projected emissions. States must also include commitments to update
their inventories periodically. The inventories themselves do not need
to be included as elements in the SIP and are not subject to EPA review
as part of the EPA's evaluation of a SIP revision.
---------------------------------------------------------------------------
\60\ 40 CFR 51.308(f)(6)(ii), (iii).
---------------------------------------------------------------------------
All States' SIPs must also provide for any other elements,
including reporting, recordkeeping, and other measures, that are
necessary for States to assess and report on visibility.\61\ A State
may note in its regional haze SIP that its compliance with the Air
Emissions Reporting Rule in 40 CFR part 51, subpart A satisfies the
requirement to provide for an emissions inventory for the most recent
year for which data are available. To satisfy the requirement to
provide estimates of future projected emissions, a State may explain in
its SIP how projected emissions were developed for use in establishing
RPGs for its own and nearby Class I areas.
---------------------------------------------------------------------------
\61\ 40 CFR 51.308(f)(6)(vi).
---------------------------------------------------------------------------
Separate from the requirements related to monitoring for regional
haze purposes under 40 CFR 51.308(f)(6), the Regional Haze Rule also
contains a requirement at section 51.308(f)(4) related to any
additional monitoring that may be needed to address visibility
impairment in Class I areas from a single source or a small group of
sources. This is called ``reasonably attributable visibility
impairment.'' \62\ Under this provision, if the EPA or the Federal Land
Manager of an affected Class I area has advised a State that additional
monitoring is needed to assess reasonably attributable visibility
impairment, the State must include in its SIP revision for the second
implementation period an appropriate strategy for evaluating such
impairment.
---------------------------------------------------------------------------
\62\ The EPA's visibility protection regulations define
``reasonably attributable visibility impairment'' as ``visibility
impairment that is caused by the emission of air pollutants from
one, or a small number of sources.'' 40 CFR 51.301.
---------------------------------------------------------------------------
F. Requirements for Periodic Reports Describing Progress Towards the
Reasonable Progress Goals
Section 51.308(f)(5) requires a State's regional haze SIP revision
to address the requirements of paragraphs 40 CFR 51.308(g)(1) through
(5) so that the plan revision due in 2021 will serve also as a progress
report addressing the period since submission of the progress report
for the first implementation period. The regional haze progress report
requirement is designed to inform the public and the EPA about a
State's implementation of its existing long-term strategy and whether
such implementation is in fact resulting in the expected visibility
improvement.\63\ To this end, every State's SIP revision for the second
implementation period is required to describe the status of
implementation of all measures included in the State's long-term
strategy, including BART and reasonable progress emission reduction
measures from the first implementation period, and the resulting
emissions reductions.\64\
---------------------------------------------------------------------------
\63\ 81 FR 26942, May 4, 2016, at page 26950; 82 FR 3078,
January 10, 2017, at page 3119.
\64\ 40 CFR 51.308(g)(1) and (2).
---------------------------------------------------------------------------
A core component of the progress report requirements is an
assessment of changes in visibility conditions on the clearest and most
impaired days. For second implementation period progress reports,
section 51.308(g)(3) requires States with Class I areas within their
borders to first determine current visibility conditions for each area
on the most impaired and clearest days, 40 CFR 51.308(g)(3)(i)(B), and
then to calculate the difference between those current conditions and
baseline (2000-2004) visibility conditions in order to assess progress
made to date.\65\ States must also assess the changes in visibility
impairment for the most impaired and clearest days since they submitted
their first implementation period progress reports.\66\ Since different
States submitted their first implementation period progress reports at
different times, the starting point for this assessment will vary.
---------------------------------------------------------------------------
\65\ 40 CFR 51.308(g)(3)(ii)(B).
\66\ 40 CFR 51.308(g)(3)(iii)(B), (f)(5).
---------------------------------------------------------------------------
Similarly, States must provide analyses tracking the change in
emissions of pollutants contributing to visibility impairment from all
sources and activities within the State over the period since they
submitted their first implementation period progress reports.\67\
Changes in emissions should be identified by the type of source or
activity. Section 51.308(g)(5) also addresses changes in emissions
since the period addressed by the previous progress report and requires
States' SIP revisions to include an assessment of any significant
changes in anthropogenic emissions within or outside the State. This
assessment must include an explanation of whether these changes in
emissions were anticipated and whether they have limited or impeded
progress in reducing emissions and improving visibility relative to
what the State projected based on its long-term strategy for the first
implementation period.
---------------------------------------------------------------------------
\67\ 40 CFR 51.308(g)(4), (f)(5).
---------------------------------------------------------------------------
G. Requirements for State and Federal Land Manager Coordination
Clean Air Act section 169A(d) requires that before a State holds a
public hearing on a proposed regional haze SIP revision, it must
consult with the appropriate Federal Land Manager or Federal Land
Managers; pursuant to that consultation, the State must include a
summary of the Federal Land Managers' conclusions and recommendations
in the notice to the public. Consistent with this statutory
requirement, the Regional Haze Rule also requires that States ``provide
the [Federal Land Manager] with an opportunity for consultation, in
person and at a point early enough in the State's policy analyses of
its long-term strategy emission reduction obligation so that
information and recommendations provided by the [Federal Land Manager]
can meaningfully inform the State's decisions on the long-term
strategy.'' \68\ Consultation that occurs 120 days prior to any public
hearing or public comment opportunity will be deemed ``early enough,''
but the Regional Haze Rule provides that in any event the opportunity
for consultation must be provided at least 60 days before a public
hearing or comment opportunity. This consultation must include the
opportunity for the Federal Land Managers to discuss their assessment
of visibility impairment in any Class I area and their recommendations
on the development and implementation of strategies to address such
impairment.\69\
---------------------------------------------------------------------------
\68\ 40 CFR 51.308(i)(2).
\69\ Ibid.
---------------------------------------------------------------------------
In order for the EPA to evaluate whether Federal Land Manager
consultation meeting the requirements of the Regional Haze Rule has
occurred, the SIP revision should include documentation of the timing
and content of such consultation. The SIP revision submitted to the EPA
must also describe how the State addressed any comments provided by the
Federal Land Managers.\70\ Finally, a SIP revision must provide
procedures for continuing consultation between the State and Federal
Land Managers regarding the State's visibility protection program,
including development and review of SIP revisions, five-year progress
reports, and the implementation of other programs having the potential
to contribute to impairment of visibility in Class I areas.\71\
---------------------------------------------------------------------------
\70\ 40 CFR 51.308(i)(3).
\71\ 40 CFR 51.308(i)(4).
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[[Page 13523]]
III. The EPA's Evaluation of the Idaho Regional Haze SIP Revision for
the Second Implementation Period
A. Background on the Idaho First Implementation Period SIP Revision
Idaho submitted its regional haze plan for the first implementation
period on October 25, 2010.\72\ The Clean Air Act required that first
implementation period plans include, among other things, a long-term
strategy for making reasonable progress and best available retrofit
technology (BART) requirements for certain older facilities, where
applicable.\73\ The EPA approved Idaho's first implementation period
plan in two actions on June 22, 2011 (76 FR 36329), and November 8,
2012 (77 FR 66929). Subsequently, on June 29, 2012, Idaho submitted
BART revisions that the EPA approved on April 28, 2014 (79 FR 23273).
On June 28, 2016, the State submitted a five-year progress report,
approved by the EPA on July 15, 2019 (84 FR 33697).\74\ In the action
to approve the progress report, the EPA determined that the Idaho
regional haze plan for the first implementation period was adequate and
required no substantive revision.\75\
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\72\ 2008 through 2018.
\73\ The requirements for regional haze SIPs for the first
implementation period are contained in Clean Air Act section
169A(b)(2)(B) and 40 CFR 51.308(d) and (e). See also 40 CFR
51.308(b).
\74\ For details, please see the progress report in the EPA's
prior action at <a href="https://www.regulations.gov">https://www.regulations.gov</a> under docket number EPA-
R10-OAR-2017-0571.
\75\ 84 FR 33697, July 15, 2019, at page 33698.
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B. The Idaho Second Implementation Period SIP Revision and the EPA's
Evaluation
On August 5, 2022, Idaho submitted a regional haze plan for the
second implementation period.\76\ Idaho made the submission available
for public comment from June 22, 2022, through July 21, 2022, and held
a public hearing on July 21, 2022.\77\ The State received and responded
to public comments and included the comments and responses in the
submission.\78\ Later, on September 27, 2024, Idaho submitted an
additional action to supplement the August 5, 2022, submission. Idaho
made the supplement available for public comment from August 12, 2024,
to September 11, 2024, and received no public comments.\79\
---------------------------------------------------------------------------
\76\ 2018 through 2028.
\77\ Idaho Regional Haze Plan State Implementation Plan for the
2nd Implementation Period (Idaho 2022 plan submission) at Appendix
C. Consultation Dates and Appendix G. Public Comment Period.
\78\ Id. at Appendix H. DEQ Responses to Public Comments.
\79\ See Idaho supplemental submission dated September 27, 2024,
at page 36 and Appendix G. Public Comment Period.
---------------------------------------------------------------------------
The following sections of this preamble describe the Idaho 2022
plan submission and the Idaho 2024 supplemental submission (herein
referred to as ``the Idaho submissions'' or ``the submissions'') and
detail the EPA's evaluation of the submission against the requirements
of the Clean Air Act and Regional Haze Rule. The Idaho submission and
the EPA's supporting documentation may be found in the docket for this
action.
C. Identification of Class I Areas
Section 169A(b)(2) of the Clean Air Act requires each State in
which any Class I area is located or ``the emissions from which may
reasonably be anticipated to cause or contribute to any impairment of
visibility'' in a Class I area to have a plan for making reasonable
progress toward the national visibility goal. The Regional Haze Rule
implements this statutory requirement at 40 CFR 51.308(f), which
provides that each State's plan ``must address regional haze in each
mandatory Class I Federal area located within the State and in each
mandatory Class I Federal area located outside the State that may be
affected by emissions from within the State,'' and (f)(2), which
requires each State's plan to include a long-term strategy that
addresses regional haze in such Class I areas.
1. Idaho Class I Areas
There are five mandatory Class I areas, or portions of such areas,
within Idaho.\80\ Craters of the Moon National Monument and Preserve,
Sawtooth Wilderness Area, and Selway-Bitterroot Wilderness Area lie
completely within Idaho State borders. The Hells Canyon Wilderness Area
is a shared Class I area with Oregon and Yellowstone National Park is a
shared Class I area with Wyoming. In its submissions, Idaho addresses
all regional haze requirements in the three Class I areas that lie
completely within Idaho.\81\ Idaho's submissions also include a long-
term strategy that addresses visibility impairment in the Hells Canyon
Wilderness and Yellowstone National Park. By agreement with Idaho,
Oregon and Wyoming, respectively, address core regional haze
requirements for these two Class I areas, including calculations of
visibility conditions, long-term strategy, reasonable progress goals,
and monitoring.\82\ Finally, Idaho's submissions address regional haze
visibility impairment in other Class I areas in neighboring States.
---------------------------------------------------------------------------
\80\ See 40 CFR 81.410.
\81\ Idaho 2022 plan submission, tables 23-28.
\82\ Id., pages 3-4.
---------------------------------------------------------------------------
a. Craters of the Moon National Monument and Preserve
The Craters of the Moon National Monument and Preserve is made up
of 43,243 acres on the Snake River Plain in south-central Idaho.\83\ It
is managed by the National Park Service and contains more than 25
volcanic cones and 60 distinct lava flows that are part of the Great
Rift volcanic zone that continues along the Snake River Plain.\84\
---------------------------------------------------------------------------
\83\ Id., page 3.
\84\ Ibid.
---------------------------------------------------------------------------
b. Hells Canyon Wilderness Area
The Hells Canyon Wilderness Area, managed by the U.S. Forest
Service, is located on the border between Oregon and Idaho. The Snake
River divides the wilderness, with 131,133 acres in Oregon, and 83,811
acres in Idaho.\85\
---------------------------------------------------------------------------
\85\ See 40 CFR 81.410.
---------------------------------------------------------------------------
c. Sawtooth Wilderness Area
The Sawtooth Wilderness Area is comprised of 216,383 acres in
central Idaho managed by the U.S. Forest Service.\86\ The wilderness
area includes the Sawtooth Mountains, home to approximately 40 peaks
over 10,000 feet.\87\
---------------------------------------------------------------------------
\86\ Ibid.
\87\ Ibid.
---------------------------------------------------------------------------
d. Selway-Bitterroot Wilderness Area
The Selway-Bitterroot Wilderness Area is located in north Idaho and
crosses the Idaho-Montana border.\88\ The area, managed by the U.S.
Forest Service, spans 1,240,700 acres of rough mountainous terrain,
dense forests, mountain lakes, and the Selway River.\89\
---------------------------------------------------------------------------
\88\ Ibid.
\89\ Ibid.
---------------------------------------------------------------------------
e. Yellowstone National Park
Yellowstone National Park, managed by the National Park Service,
covers 2.2 million acres, primarily in Wyoming.\90\ A small portion of
the park is located in eastern Idaho.
---------------------------------------------------------------------------
\90\ Ibid.
---------------------------------------------------------------------------
2. Idaho Visibility Monitors
Haze species are measured and analyzed via the Interagency
Monitoring of Protected Visual Environments (IMPROVE) network.\91\
Table 1 of this preamble lists the IMPROVE monitors representing
visibility at Idaho Class I areas.
---------------------------------------------------------------------------
\91\ IMPROVE website at <a href="http://vista.cira.colostate.edu/Improve">http://vista.cira.colostate.edu/Improve</a>.
[[Page 13524]]
Table 1--Monitors Representing Visibility at Idaho Class I Areas \92\
------------------------------------------------------------------------
Monitor ID Sponsor Class I area Years operated
------------------------------------------------------------------------
CRMO1........... National Park Craters of the Moon 2001-present.
Service. National Monument
and Preserve.
HECA1........... U.S. Forest Hells Canyon 2001-present.
Service. Wilderness Area.
SAWT1........... U.S. Forest Sawtooth Wilderness 2001-present.
Service. Area.
SULA1........... U.S. Forest Selway-Bitterroot 2001-present.
Service. Wilderness Area.
YELL2........... National Park Yellowstone National 1991-present.
Service. Park.
------------------------------------------------------------------------
In the submissions, Idaho documented that the State had consulted
with Montana, Nevada, Oregon, Utah, Washington, and Wyoming on
potential interstate visibility impacts to shared Class I areas and
Class I areas outside of Idaho.\93\ The Idaho Department of
Environmental Quality (Idaho DEQ) shared source selection and
evaluation data, however, no other State requested Idaho undertake
additional four-factor analyses on top of those already conducted by
Idaho.\94\ Idaho committed to continued consultation with states in the
west on interstate visibility contributions.\95\
---------------------------------------------------------------------------
\92\ Sources: Idaho 2022 plan submission at page 11 and Federal
Land Manager Environmental Database at <a href="https://views.cira.colostate.edu/fed/">https://views.cira.colostate.edu/fed/</a>.
\93\ Idaho 2022 plan submission, pages 86-90.
\94\ Id., pages 89-90.
\95\ Id., page 96.
---------------------------------------------------------------------------
D. Calculations of Baseline, Current, and Natural Visibility
Conditions; Progress to Date; and the Uniform Rate of Progress
Section 51.308(f)(1) requires States to determine the following for
``each mandatory Class I Federal area located within the State'':
baseline visibility conditions for the most impaired and clearest days,
natural visibility conditions for the most impaired and clearest days,
progress to date for the most impaired and clearest days, the
differences between current visibility conditions and natural
visibility conditions, and the uniform rate of progress. This section
also provides the option for States to propose adjustments to the
uniform rate of progress line for a Class I area to account for
visibility impacts from anthropogenic sources outside the U.S. and/or
the impacts from wildland prescribed fires that were conducted for
certain, specified objectives.\96\
---------------------------------------------------------------------------
\96\ 40 CFR 51.308(f)(1)(vi)(B).
---------------------------------------------------------------------------
1. Idaho Visibility Conditions
The Idaho submissions addressed baseline, current and natural
visibility conditions and the uniform rate of progress for Craters of
the Moon National Monument and Preserve, Sawtooth Wilderness Area, and
Selway-Bitterroot Wilderness Area, as required by the 2017 Regional
Haze Rule and the EPA's technical guidance on tracking visibility
progress.\97\ Table 2 of this preamble summarizes visibility progress
on the clearest days. Table 3 of this preamble summarizes visibility
progress on the most impaired days, including adjustments to each Class
I area's uniform rate of progress (URP) and natural conditions endpoint
that the EPA modeled to account for certain international anthropogenic
emissions and wildland prescribed fires.\98\
---------------------------------------------------------------------------
\97\ EPA Technical Guidance on Tracking Visibility Progress for
the Second Implementation Period of the Regional Haze Program,
December 2018. Idaho defers to Oregon and Wyoming to provide this
information for Hells Canyon Wilderness Area and Yellowstone
National Park. See 89 FR 13622, February 23, 2024, at page 13636; 89
FR 95121, December 2, 2024, at page 95125.
\98\ Technical Support Document for the EPA's 2028 Updated
Regional Haze Modeling, September 19, 2019.
\99\ Source: Idaho 2022 plan submission, table 6, page 12.
\100\ Sources: Idaho 2022 plan submission, table 4, page 11, and
Technical Support Document for the EPA's 2028 Updated Regional Haze
Modeling, September 19, 2019.
Table 2--Clearest Days Visibility Conditions at Idaho Class I Areas in Deciviews \99\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline 2000- Current 2014- Progress to Current minus
Monitor ID Class I area 2004 2018 Natural 2064 date \a\ Natural \b\
--------------------------------------------------------------------------------------------------------------------------------------------------------
CRMO1............................... Craters of the Moon National 4.31 2.68 1.73 1.63 0.95
Monument and Preserve.
SAWT1............................... Sawtooth Wilderness Area.......... 4.00 2.58 1.51 1.42 1.07
SULA1............................... Selway-Bitterroot Wilderness Area. 2.57 1.60 1.12 0.97 0.48
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Progress to date is the difference between the baseline and current conditions. A positive value indicates that visibility has improved.
\b\ A positive value indicates that current visibility has not reached natural conditions.
Table 3--Most Impaired Days Visibility Conditions at Idaho Class I Areas in Deciviews \100\
--------------------------------------------------------------------------------------------------------------------------------------------------------
EPA-
Baseline Current Un-adjusted EPA- Natural Progress to Current adjusted
Monitor ID Class I Area 2000-2004 2014-2018 URP 2028 adjusted 2064 date minus Natural
URP 2028 Natural 2064
--------------------------------------------------------------------------------------------------------------------------------------------------------
CRMO1................... Craters of the Moon 11.91 8.50 9.13 10.17 4.97 3.41 3.53 7.56
National Monument and
Preserve.
SAWT1................... Sawtooth Wilderness 9.61 8.61 7.64 8.33 4.67 1 3.91 6.41
Area.
SULA1................... Selway-Bitterroot 10.06 8.37 8.23 9.07 5.48 1.69 2.92 7.58
Wilderness Area.
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 13525]]
The data in Tables 2 and 3 of this preamble indicate that current
visibility has improved since the baseline period for both the clearest
and most impaired days for each Class I area. In addition, Idaho
included both the URP and an adjusted URP.
Idaho relied upon the WRAP regional scale modeling using CAMx
2028OTBa2 H-L SA to adjust the URP.\101\ The model projected
international emissions and prescribed fire contributions, which the
WRAP then used to adjust the natural visibility conditions in
2064.\102\ The EPA proposes to determine that Idaho used scientifically
valid data and methods for estimating the impacts of international
emissions and wildland prescribed fire in the three Class I areas.\103\
The EPA proposes to find that the Idaho submissions meet the
requirements of 40 CFR 51.308(f)(1) to calculate baseline, current, and
natural visibility conditions; progress to date; and the uniform rate
of progress, including an adjusted URP, for the second implementation
period.
---------------------------------------------------------------------------
\101\ Idaho 2022 plan submission, page 92.
\102\ Id.
\103\ 40 CFR 51.308(f)(1)(vi)(B).
---------------------------------------------------------------------------
E. Long-Term Strategy for Regional Haze
Each State having a Class I area within its borders or emissions
that may affect visibility in a Class I area must develop a long-term
strategy for making reasonable progress towards the national visibility
goal.\104\ As explained in the background discussion in section I. of
this preamble, reasonable progress is achieved when all States
contributing to visibility impairment in a Class I area are
implementing the measures determined--through application of the four
statutory factors to sources of visibility impairing pollutants--to be
necessary to make reasonable progress.\105\ Each state's long-term
strategy must include the enforceable emission limitations, compliance
schedules, and other measures that are necessary to make reasonable
progress.\106\ After considering the four statutory factors, all
measures that are determined to be necessary to make reasonable
progress must be in the long-term strategy. In developing its long-term
strategy, a State must also consider five additional factors.\107\ As
part of its reasonable progress determinations, the State must describe
the criteria used to determine which sources or group of sources were
evaluated (i.e., subjected to four-factor analysis) for the second
implementation period and how the four factors were taken into
consideration in selecting the emission reduction measures for
inclusion in the long-term strategy.\108\
---------------------------------------------------------------------------
\104\ Clean Air Act section 169A(b)(2)(B).
\105\ 40 CFR 51.308(f)(2)(i).
\106\ 40 CFR 51.308(f)(2).
\107\ 40 CFR 51.308(f)(2)(iv).
\108\ 40 CFR 51.308(f)(2)(iii).
---------------------------------------------------------------------------
States may rely on technical information developed by the regional
planning organizations of which they are members to select sources for
four-factor analysis and to conduct that analysis, as well as to
satisfy the documentation requirements under section 51.308(f). Where a
regional planning organization has performed source selection and/or
four-factor analyses (or considered the five additional factors in
section 51.308(f)(2)(iv)) for its member States, those States may rely
on the regional planning organization's analyses for the purpose of
satisfying the requirements of section 51.308(f)(2)(i) so long as the
States have a reasonable basis to do so and all State participants in
the regional planning organization process have approved the technical
analyses.\109\ States may also satisfy the requirement of section
51.308(f)(2)(ii) to engage in interstate consultation with other States
that have emissions that are reasonably anticipated to contribute to
visibility impairment in a given Class I area under the auspices of
intra- and inter-regional planning organization engagement.
---------------------------------------------------------------------------
\109\ 40 CFR 51.308(f)(3)(iii).
---------------------------------------------------------------------------
The following paragraphs describe how the Idaho submissions
addressed the requirements of 40 CFR 51.308(f)(2) and summarizes the
EPA's evaluation of Idaho's submissions.
1. Pollutants Impacting Visibility at Idaho Class I Areas
Idaho evaluated the haze composition at each of the IMPROVE
monitors representing visibility at the Craters of the Moon National
Monument and Preserve (CRMO1), Sawtooth Wilderness Area (SAWT1), and
Selway-Bitterroot Wilderness Area (SULA1). In the submissions, Idaho
illustrated that ammonium nitrate contributed the most to total light
extinction at the CRMO1 monitor, followed by ammonium sulfate for each
year from 2001 through 2018.\110\ Idaho determined that the most
impaired days at CRMO1 occurred mainly in the fall and winter and that
nitrate and sulfate contributed the most to light extinction on these
fall and winter most impaired days.\111\
---------------------------------------------------------------------------
\110\ Idaho 2022 plan submission, pages 13-16.
\111\ Id., page 15.
---------------------------------------------------------------------------
The Idaho submissions documented that organic carbon contributed
the most to total light extinction at the SAWT1 monitor followed by
ammonium sulfate for each year from 2001 through 2018.\112\ Idaho
determined that the anthropogenic contributions of ammonium nitrate
were smaller at SAWT1, and that the anthropogenic fractions of organic
carbon, elemental carbon and sulfate light extinction were the
predominant contributors to annual haze at the monitor.\113\
---------------------------------------------------------------------------
\112\ Id., pages 16-19.
\113\ Ibid.
---------------------------------------------------------------------------
With respect to the SULA1 monitor, Idaho stated in the submissions
that average aerosol light extinction on the most impaired days was
largely from organic carbon and ammonium sulfate (47% and 25%,
respectively), however lower levels of coarse mass, elemental carbon,
ammonium nitrate, and fine soil were also present.\114\ Idaho stated
that the most impaired days occurred in the spring, summer, and
fall.\115\ According to Idaho, during these months, organic carbon made
up the largest proportion of visibility impairing pollutants.\116\
---------------------------------------------------------------------------
\114\ Id., pages 19-22.
\115\ Ibid.
\116\ Id.
---------------------------------------------------------------------------
A review of IMPROVE data confirms the State's analysis of average
haze composition at Idaho IMPROVE monitors and supports the State's
decision to evaluate NO<INF>X</INF>, SO<INF>2</INF>, and
PM<INF>10</INF> contributions to haze.\117\ Importantly, Idaho
evaluated specific pollutant emissions on a unit-by-unit basis for each
source as described in the following paragraphs of this preamble.
---------------------------------------------------------------------------
\117\ See ``Haze Composition at Idaho Class I Areas.xls'' in the
docket for this action. Annual average extinction composition for
the years 2001 through 2022 for CRMO1, SAWT1, and SULA1. Data pulled
from FED AQRV Visibility Tools. Federal Land Manager Environmental
Database (FED); CSU and the Cooperative Institute for Research in
the Atmosphere (CIRA).
---------------------------------------------------------------------------
2. Idaho Source Selection
According to the State's submissions, Idaho used the source
selection methodology developed by the WRAP for western States.\118\
The WRAP's approach used the Q/d method, where Q is the sum of
visibility impairing pollutants (NO<INF>X</INF>, SO<INF>2</INF> and
PM<INF>10</INF>), and d is the distance (kilometers) to the boundary of
the nearest Class I area. The Idaho DEQ screened sources as described
in the following steps: \119\
---------------------------------------------------------------------------
\118\ See the WRAP Technical Support System (TSS) at
<a href="http://www.wrapair2.org">www.wrapair2.org</a>.
\119\ Idaho 2022 plan submission, page 54.
---------------------------------------------------------------------------
1. Identify those facilities with total facility-wide emissions of
visibility impairing pollutants (NO<INF>X</INF>, SO<INF>2</INF> and
PM<INF>10</INF>) greater than 25 tons per year (tpy) based on 2014
National Emissions Inventory (NEI) data.
2. Calculate the distance from each facility identified in Step 1
to the
[[Page 13526]]
nearest Class I area boundary (including those in other States) in
kilometers (km). Facilities greater than 400 km from the nearest Class
I area were considered to have minimal impact on visibility and were
excluded.
3. Identify those facilities with a Q/d greater than the State-
defined threshold. Idaho used a Q/d threshold of 2.0 because the State
estimated that the threshold captured 70% to 80% of emissions from
Idaho facilities.
4. Refine the Q/d analysis using more recent 2017 NEI data to
screen out sources that have a Q/d less than the State-defined
threshold for 2017 emissions.
Idaho's initial source screening used 2014 emissions inventory data
to identify 14 facilities in Idaho with Q/d greater than 2.0.\120\
Refining the Q/d analysis using 2017 emissions inventory data screened
out three additional facilities from the original 14 (Idaho Forest
Group LLC-Riley Creek-Moyie Springs, Plummer Forest Group, Inc-Post
Falls, and Rexburg Facility of Basic American Foods).\121\ Idaho also
screened out a facility outside of the State's regulatory purview
(Boise Airport) and screened out a facility near Sawtooth Wilderness
Area (Northwest Pipeline--Mountain Home) because the facility primarily
emitted NO<INF>X</INF>. Idaho stated this was appropriate because
anthropogenic contributions to NO<INF>X</INF> at SAWT1 were found to be
negligible.\122\ This screening process yielded nine Idaho facilities
with Q/d greater than 2.0.
---------------------------------------------------------------------------
\120\ Idaho 2022 plan submission, page 55. See table 22 as
updated by Idaho 2024 supplemental submission.
\121\ Id., page 55.
\122\ Id., page 56. See also figure 11.
---------------------------------------------------------------------------
Idaho also used the WRAP weighted emissions potential (WEP) to
confirm the selected sources.\123\ According to Idaho's submissions,
the WEP is a screening tool used to identified those sources
contributing to visibility impairment in the 2014-2018 period and still
operating in 2028 that have the potential to contribute to haze
formation at Class I areas.\124\ The rank point analysis consists of
facility-level 2028 emissions for NO<INF>X</INF> or SO<INF>2</INF>
sources overlaid with the corresponding extinction-weighted residence
time for ammonium nitrate or ammonium sulfate.\125\
---------------------------------------------------------------------------
\123\ Id., pages 61-62.
\124\ Id.
\125\ Id.
---------------------------------------------------------------------------
Idaho also identified 27 Class I areas in five neighboring states
(Montana, Nevada, Oregon, Washington, Wyoming) that could potentially
be affected by emissions from sources within Idaho. However, applying
the same source screening analysis yielded no additional Idaho
facilities beyond the nine already selected for four-factor
analysis.\126\ Table 4 of this preamble lists the final nine selected
sources.
---------------------------------------------------------------------------
\126\ Id., tables 24-28.
\127\ Source: table 22 of Idaho 2022 plan submission, as
corrected by Idaho 2024 supplemental submission.
Table 4--Idaho Selected Sources \127\
----------------------------------------------------------------------------------------------------------------
Facility Nearest Class I area Distance (km) 2017 (tpy) 2017 Q/d
----------------------------------------------------------------------------------------------------------------
P4 Production LLC (TV Facility) (P4).. Grand Teton National 111.9 2,938.4 26.3
Park.
Clearwater Paper Corp-Pulp and Paper Hells Canyon Wilderness. 70.9 1,554 21.9
and Consumer Products (Clearwater
Paper).
The Amalgamated Sugar Company LLC-Twin Jarbidge Wilderness..... 95.6 1,420 14.8
Falls (TASCO-Twin Falls).
J.R. Simplot Company-Don Siding Craters of the Moon 86.1 876.3 10.2
Pocatello (Simplot). Wilderness.
The Amalgamated Sugar Company LLC-Paul Craters of the Moon 78.0 577 7.3
(TASCO-Paul). Wilderness.
Northwest Pipeline LLC-Soda Springs Grand Teton National 122.2 579.8 4.7
(NWP). Park.
ITAFOS Conda LLC (ITAFOS)............. Grand Teton National 104.0 477.7 4.6
Park.
The Amalgamated Sugar Company LLC- Sawtooth Wilderness..... 114.6 590.9 5.1
Nampa (TASCO-Nampa).
Tamarack Mill, LLC Dba Evergreen Hells Canyon Wilderness. 25.5 69.1 2.7
Forest and Tamarack Energy
Partnership (Tamarack Mills).
----------------------------------------------------------------------------------------------------------------
3. Emissions Units and Pollutants
After selecting the nine sources, Idaho used the following steps to
identify specific emissions units at each source: (1) Exclude processes
or emissions units that emitted less than 20 tons per year of
NO<INF>X</INF>, SO<INF>2</INF>, and PM<INF>10</INF> combined (based on
2014 and/or 2017 NEI data); (2) Identify those processes and emissions
units where the summed emissions make up 70% or more of the total
facility-wide emissions; (3) Identify the pollutant(s) of concern for
the nearest Class I area for each facility, using the IMPROVE
monitoring data and WEP ranking.\128\ Table 5 of this preamble shows
the emissions units and pollutants Idaho selected for review.
---------------------------------------------------------------------------
\128\ Idaho 2022 plan submission, appendix D.
\129\ Source: Idaho 2022 plan submission, page 64. See table 31
as corrected by Idaho 2024 supplemental submission.
Table 5--Idaho Emissions Units and Pollutant Selected for Four-Factor Analysis \129\
----------------------------------------------------------------------------------------------------------------
Facility Emissions unit Pollutants
----------------------------------------------------------------------------------------------------------------
Clearwater Paper........................ No. 4 Power Boiler.............. NOX, SO2.
Clearwater Paper........................ No. 4 Recovery Furnace.......... NOX, PM10.
Clearwater Paper........................ No. 5 Recovery Furnace.......... NOX, PM10.
ITAFOS.................................. East Sulfuric Acid Plant........ SO2.
NWP-Soda Springs........................ RICE 4 (TCVA-16)................ NOX.
NWP-Soda Springs........................ RICE 1-3 (TLA-6 Engines)........ NOX.
P4...................................... Nodulizing Kiln................. NOX, SO2, PM10.
Simplot................................. No. 300 Sulfuric Acid Plant..... SO2, PM10.
[[Page 13527]]
Simplot................................. No. 400 Sulfuric Acid Plant..... NOX, SO2.
Tamarack Mills.......................... Riley Cogeneration Boiler....... NOX, PM10.
TASCO-Nampa............................. Riley Boiler.................... NOX, SO2, PM10.
TASCO-Paul.............................. B&W Boiler...................... NOX.
TASCO-Paul.............................. Rentech Boiler.................. NOX.
TASCO-Paul.............................. North and South Pulp Dryers..... NOX, SO2, PM10.
TASCO-Twin Falls........................ Foster Wheeler Boiler........... NOX, SO2, PM10.
TASCO-Twin Falls........................ B&W Boiler...................... NOX, SO2, PM10.
----------------------------------------------------------------------------------------------------------------
Based on a review of the information provided in the submission, we
propose to determine that the Idaho source, unit, and pollutant
selection methodology used for the regional haze second implementation
period satisfies the requirement in 40 CFR 51.308(f)(2)(i) that the
State include in its SIP a description of the criteria it used to
determine which sources it evaluated.
4. Idaho Control Analyses and Determinations
In developing its regional haze second implementation period plan
submission, Idaho established a cost threshold of $6,100 per ton
pollutant removed by adjusting the $5,000 per ton BART cost-
effectiveness threshold (used during the first implementation period)
for inflation.\130\ The EPA did not establish a cost-effectiveness
threshold for the second implementation period. Rather, the EPA's 2019
Guidance on Regional Haze State Implementation Plans for the Second
Implementation Period (EPA 2019 Guidance) clarified that States have
the flexibility to decide a reasonable approach to evaluating
costs.\131\
---------------------------------------------------------------------------
\130\ Idaho 2022 plan submission, pages 64 and 65.
\131\ Guidance on Regional Haze State Implementation Plans for
the Second Implementation Period. The EPA Office of Air Quality
Planning and Standards, Research Triangle Park (August 20, 2019),
page 38 (EPA 2019 Guidance), available in the docket for this action
and at <a href="https://www.epa.gov/visibility/guidance-regional-haze-state-implementation-plans-second-implementation-period">https://www.epa.gov/visibility/guidance-regional-haze-state-implementation-plans-second-implementation-period</a>.
---------------------------------------------------------------------------
Table 6 of this preamble lists the control technologies, fuel
specifications, and emission limits that Idaho determined are necessary
for reasonable progress in the second implementation period, and the
associated permit conditions that make the controls enforceable as a
practical matter, including compliance schedules, monitoring,
recordkeeping and reporting requirements.
Table 6--Idaho Regional Haze Requirements \132\
----------------------------------------------------------------------------------------------------------------
Facility Emissions unit Requirement Mechanism
----------------------------------------------------------------------------------------------------------------
Clearwater Paper.................. No. 4 Power Boiler... 5.4 SO2 emissions not to Permit T1-2020.0024
exceed 0.80 lb/MMBtu (30- issued March 30, 2023;
day average). conditions 5.4, 5.5,
5.5 NOX emissions not to 5.6, 5.7, 5.10 through
exceed 0.2 lb/MMBtu (3-hr 5.15, 26.22, and 26.23.
rolling average) when
burning wood waste/gas
and 0.3 lb/MMBtu (3-hr
rolling average) when
burning wood waste/gas.
5.6 NOX emissions not to
exceed 0.20 lb/MMBtu (3-
hr rolling average) when
burning gaseous fossil
fuel and 0.3 lb/MMBtu (3-
hr rolling average) when
burning liquid fossil
fuel, liquid fossil fuel/
wood, or gaseous fossil
fuel/wood.
5.7 SO2 emissions not to
exceed 100 tons per any
consecutive 12-month
period.
Clearwater Paper.................. No. 4 Recovery 8.1 PM emissions not to Permit T1-2020.0024
Furnace. exceed 0.040 gr/dscf at issued March 30, 2023;
8% oxygen using ESP. conditions 7.1, 7.4,
7.9, 7.10, 8.1, 8.6,
26.22, 26.23, 26.26,
26.27, 26.28, and 26.29.
Clearwater Paper.................. No. 5 Recovery 9.1 PM emissions not to Permit T1-2020.0024
Furnace. exceed 0.044 gr/dscf at issued November 26,
8% oxygen using ESP. 2021; conditions 7.1,
9.2 PM emissions not to 7.4, 7.9, 7.10, 9.1,
exceed 58 lb/hr or 0.03 9.2, 9.6, 9.11, 26.22,
gr/dscf. 26.23, 26.26, 26.27,
26.28, and 26.29.
9.6 NOX emissions not to .........................
exceed 160 lb/hr, 700
tons/year, or 100 ppm on
a dry basis at 8% oxygen.
ITAFOS............................ East Sulfuric Acid 5.1 SO2 emissions not to Permit T1-2016.0015
Plant. exceed 258 lb/hr and issued March 2, 2022;
735.5 tpy. conditions 5.1, 5.4,
5.5, 5.11, 16.22, and
16.23.
NWP-Soda Springs.................. RICE 1-3 (Clark TLA-6 Replace the four existing Compliance Agreement
Engines) RICE 4 RICE engines with two gas- Schedule Case No. E-
(Clark TCVA-16). fired turbines by July 2023.0011 dated
31, 2031. September 1, 2023.
P4................................ Nodulizing Kiln...... PM10 emissions not to Permit T1-2020.0029
exceed 30.0 lb/hr. issued December 23,
SO2 emissions not to 2021; conditions 4.2,
exceed 143 lb/hr. 4.4, 4.5, 4.6, 4.7,
4.19, 4.20, 4.21, 13.22,
and 13.33.
[[Page 13528]]
P4................................ Nodulizing Kiln...... Conduct NOX emissions Compliance Agreement
testing and establish NOX Schedule Case No. E-
emission limit. 2023.0013 dated November
27, 2023.
P4................................ Cooler Spray Tower... 4.2 PM10 emissions not to Permit T1-2020.0029
exceed 27.0 lb/hr. issued December 23,
4.2 SO2 emissions not to 2021; conditions 4.2,
exceed 177 lb/hr. 4.4, 4.5, 4.6, 4.7,
4.19, 4.20, 4.21, 13.22,
and 13.33.
Simplot........................... No. 300 Sulfuric Acid 15.9 PM10 emissions not to Permit T1-2017.0024
Plant. exceed 11.4 lb/hr based issued March 29, 2023;
on 24-hour average and conditions 15.9, 15.10,
49.8 tpy based on any 15.11, 15.19, 15.20,
consecutive 12-month 15.21, 15.22, 15.25,
period using mist 15.27, 16.19, 18.22, and
eliminators and wet 18.23.
scrubbers (Related
Consent Agreement in
Portneuf Valley PM 10
SIP).
15.10 SO2 emissions not to .........................
exceed 2.5 lb/ton of 100%
sulfuric acid produced on
a rolling 3-hour average
basis, except during
periods of startup,
shutdown, or malfunction.
15.10 SO2 emissions not to .........................
exceed 1.5 lb/ton 100%
sulfuric acid produced on
a rolling 365-day average
basis including periods
of startup, shutdown, or
malfunction.
15.11 SO2 emissions not to .........................
exceed 4.0 lb/ton of 100%
sulfuric acid produced
(Portneuf Valley PM 10
SIP).
15.11 SO2 emissions not to .........................
exceed 170 lb/hr
calculated as a 3-hr
rolling average and 750
tpy based on any
consecutive 12-month
period (Portneuf Valley
PM 10 SIP).
15.11 SO2 emissions not to .........................
exceed 28 lb/ton of 100%
sulfuric acid produced in
accordance with IDAPA
58.01.01.846 (Portneuf
Valley PM 10 SIP).
Simplot........................... No. 400 Sulfuric Acid 16.6 NOX emissions not to Permit T1-2017.0024
Plant. exceed 10.1 lb/hr (24- issued March 29, 2023;
hour average) (Portneuf conditions 16.6, 16.9,
Valley PM 10 SIP). 16.10, 16.19, 16.20,
16.6 NOX emissions not to 16.21, 16.22, 16.26,
exceed 42.1 tpy based on 16.27, 18.22, and 18.23.
any consecutive 12-month Permit T1-9507-114-1
period (Portneuf Valley issued April 5, 2004
PM 10 SIP). (incorporated by
16.9 SO2 emissions not to reference into the Idaho
exceed 2.5 lb/ton of 100% SIP at 40 CFR
sulfuric acid produced on 52.670(d)); conditions.
a rolling 3-hour average
basis, except during
periods of startup,
shutdown, or malfunction.
16.9 SO2 emissions not to
exceed 1.6 lb/ton 100%
sulfuric acid produced on
a rolling 365-day average
basis including periods
of startup, shutdown, or
malfunction.
16.10 SO2 emissions not to
exceed 4 lb/ton of 100%
sulfuric acid produced
and 999 lb per each
running three-hour period
(Portneuf Valley PM 10
SIP).
Tamarack Mills.................... Riley Cogeneration 5.2 PM2.5/PM10 emissions Permit T1-2019-0024
Boiler. not to exceed 18.00 lb/hr. issued October 17, 2022;
5.2 NOX emissions not to conditions 5.2, 5.3,
exceed 22.44 lb/hr. 5.5, 5.8, 5.17, 10.22,
5.3 Particulate matter and 10.23.
emissions not to exceed
0.080 gr/dscf at 8%
oxygen.
5.5 Fire wood waste
exclusively, as defined.
TASCO-Nampa....................... Riley Boiler......... 4.8 Fire exclusively on Permit P-2018.0011 issued
natural gas and no longer February 15, 2023;
fire coal by July 1, 2027. condition 4.8.
TASCO-Paul........................ B&W Boiler........... NOX emissions not to Permit T1-2019-0020
exceed 132.0 tpy. issued November 5, 2021;
Combust natural gas only.. conditions 4.4, 4.5,
Operate up to two of the 4.6, 4.7, 4.10, 11.22,
three boilers and 11.23.
simultaneously except
during startup and
shutdown when the three
boilers may be partially
operated.
Operation of the three
boilers shall not exceed
40,000,000 therms (for
all boilers combined) for
the campaign year as
defined.
[[Page 13529]]
TASCO-Paul........................ Rentech Boiler....... 4.3 NOX emissions not to Permit T1-2019-0020
exceed 0.10 lb/MMBtu (30- issued November 5, 2021;
day average). conditions 4.3, 4.4,
4.4 NOX emissions not to 4.5, 4.6, 4.7, 4.9,
exceed 132.0 tpy.. 4.10, 4.11, 4.12, 4.15,
4.5 Combust natural gas 4.16, 4.18, 11.22, and
only.. 11.23.
4.6 Operate up to two of
the three boilers
simultaneously except
during startup and
shutdown when the three
boilers may be partially
operated.
4.7 Operation of the three
boilers shall not exceed
40,000,000 therms (for
all boilers combined) for
the campaign year as
defined.
4.9 Maximum heat input
capacity shall not exceed
385 MMBtu/hr.
TASCO-Twin Falls.................. Foster Wheeler Boiler 4.9 On and after January Permit T1-2016.0017,
1, 2023, fuel exclusively issued on January 21,
by natural gas. 2022; condition 4.9.
TASCO-Twin Falls.................. B&W Boiler........... 5.2 Only combust natural Permit T1-2016.0017,
gas as fuel. issued on January 21,
2022; condition 5.2.
----------------------------------------------------------------------------------------------------------------
The following paragraphs of this preamble describe the Idaho
control analyses and determinations and summarize the EPA's review by
facility. For the reasons set forth in the following paragraphs, the
EPA is proposing to approve Idaho's 2022 and 2024 SIP submissions as
meeting the requirement in 40 CFR 51.308(f)(2)(i) that the State submit
a long-term strategy that includes the enforceable emissions
limitations, compliance schedules, and other measures that are
necessary for reasonable progress based on an evaluation of the four
statutory factors.
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\132\ Idaho 2022 plan submission as updated by Idaho 2024
supplemental submission. See tables 37a, 37b, 38, 39, 40, 41a, 41b,
42.
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a. Clearwater Paper (Idaho DEQ Facility ID 069-00001)
i. Background
Clearwater Paper is a large kraft pulp mill located in Lewiston,
Idaho. The mill converts chipped wood and sawdust into bleached pulp
through a series of digestion, washing, screening, delignification, and
bleaching operations. In the two recovery furnaces, the bleached pulp
is formed, dried, treated, and sized to produce paperboard or consumer
products.\133\ Both recovery furnaces fire black liquor and natural gas
and are equipped with electrostatic precipitators (ESPs) to control
particulate matter.\134\
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\133\ Idaho 2022 plan submission, Appendix B. Four-Factor
Analyses and Reviews. Clearwater Paper Corp.--Pulp and Paperboard
Division.
\134\ Idaho 2022 plan submission, pages 80 and 81.
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Power for the facility is produced by three boilers that combust
natural gas and fuel oil, in addition to a fourth high-pressure, high-
temperature boiler that combusts cellulosic biomass (hog fuel, bark,
lumber, chips sawdust, sander dust, wood pallets, clean wood),
dewatered pulp and paper sludge, natural gas, and fuel oil.\135\
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\135\ Idaho 2022 plan submission, Appendix B. Four-Factor
Analyses and Reviews. Clearwater Paper Corp.--Pulp and Paperboard
Division.
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ii. Idaho Control Determination
Clearwater Paper: No. 4 and No. 5 Recovery Furnaces
Idaho conducted a review of NO<INF>X</INF> and PM<INF>10</INF>
retrofit control options for the No. 4 and 5 recovery furnaces.
For NO<INF>X</INF>, Idaho determined that it would not be
technically feasible to retrofit the No. 4 and No. 5 recovery furnaces
with low NO<INF>X</INF> burners, ultra low NO<INF>X</INF> burners
(ULNB), flue gas recirculation, overfire air, selective non-catalytic
reduction (SNCR), selective catalytic reduction (SCR), or low-
temperature oxidation (LoTOx) technologies. Among other reasons, Idaho
argued that those technologies have not been utilized on recovery
furnaces that burn black liquor solids.\136\ The facility stated that a
quarternary air system has been implemented at just one similar
facility in the U.S., where it was installed to comply with lowest
achievable emission rate (LAER) requirements under Clean Air Act title
I, part D (with an associated NO<INF>X</INF> emissions limit of 85
parts per million by volume, dry (ppmvd) at 8% oxygen).\137\ Because
the No. 4 recovery furnace was previously found to be emitting
NO<INF>X</INF> at an even lower rate (75 ppmvd at 8% oxygen), Idaho
determined that it was reasonable to conclude that installation of a
quaternary air system would not reduce NO<INF>X</INF> emissions from
the No. 4 recovery furnace.\138\
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\136\ Ibid.
\137\ Ibid.
\138\ Id. at page 10.
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Furthermore, Idaho stated that the No. 5 recovery furnace is
already subject to major source pre-construction permitting limits for
NO<INF>X</INF> (160 pounds per hour or 700 tons per year or 100 ppm) as
set forth in the facility's operating permit and that NO<INF>X</INF>
emissions have remained constant since 2014.\139\ Idaho therefore
determined that the NO<INF>X</INF> emission limits established through
the PSD process constituted existing effective controls for the No. 5
recovery furnace.
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\139\ Idaho 2022 plan submission, table 37; page 81.
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For PM<INF>10</INF>, Idaho stated that the No. 4 and No. 5 recovery
furnaces are subject to National Emission Standards for Hazardous Air
Pollutants (NESHAP) for Chemical Recovery Combustion Sources at Kraft,
Soda, Sulfite, and Stand-Alone Semichemical Pulp Mills at 40 CFR part
63, subpart MM.\140\ The NESHAP requires the use of electrostatic
precipitators (ESPs) to comply with Maximum Available Control
Technology (MACT) limits of 0.044 and 0.030 grains per dry standard
cubic foot (gr/dscf) corrected to 8% oxygen, respectively.\141\ Idaho
determined that these requirements constituted existing effective
controls for PM<INF>10</INF>.
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\140\ Idaho 2022 plan submission, Appendix B. Four-Factor
Analyses and Reviews. Clearwater Paper Corp.--Pulp and Paperboard
Division.
\141\ Ibid.
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Clearwater Paper: No. 4 Power Boiler
Idaho noted that the No. 4 power boiler was retrofitted with an
overfire air system in 2016 and is currently subject to the
NO<INF>X</INF> emission limits in the New Source Performance Standards
(NSPS) for Fossil-Fuel-Fired Steam
[[Page 13530]]
Generators in 40 CFR part 60, subpart D, specifically 0.20 lb/MMBtu
NO<INF>X</INF> when firing natural gas and 0.30 lb/MMBtu NO<INF>X</INF>
when firing wood or fuel oil.\142\ Idaho evaluated additional retrofit
NO<INF>X</INF> and SO<INF>2</INF> controls for the No. 4 power boiler
under the four statutory factors.\143\ For NO<INF>X</INF>, Idaho
assessed the feasibility and costs of retrofitting the boiler with
additional NO<INF>X</INF> controls, including LNB, ULNB, SNCR, SCR, and
LoTOx.\144\ Idaho determined that ULNB and flue gas recirculation were
technologically infeasible. For the remaining, feasible controls, Idaho
concluded that the cost to install any one of these systems would
exceed the State's established cost-effectiveness threshold.\145\
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\142\ Idaho 2022 plan submission, page 80.
\143\ Id., page 2.
\144\ Id., page 3.
\145\ Idaho 2022 plan submission, Appendix B. Four-Factor
Analyses and Reviews. Clearwater Paper Corp.--Pulp and Paperboard
Division.
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Thus, the State concluded that the existing overfire air system and
current permitted NO<INF>X</INF> limits for the No. 4 power boiler were
necessary for reasonable progress.
For SO<INF>2</INF>, the State identified retrofitting the No. 4
power boiler with a wet scrubber, lime spray dryer and baghouse,
circulating dry scrubber, and reducing the sulfur content of the fuel
as potential SO<INF>2</INF> controls. Idaho determined that reducing
the sulfur content of fuel fired in the No. 4 power boiler was not
feasible, most notably because the sulfur content of the hog fuel fired
in the boiler is variable and difficult to control.\146\ The State
determined that retrofitting the No. 4 power boiler with a wet
scrubber, lime spray dryer and baghouse, or circulating dry scrubber
were each technically feasible SO<INF>2</INF> control options, however,
Idaho estimated the cost of compliance for each of these technically
feasible SO<INF>2</INF> control options would exceed the State's
established cost-effectiveness threshold.\147\ Idaho therefore
determined that the NSPS requirements for Fossil-Fuel-Fired Steam
Generators in 40 CFR part 60, subpart D, specifically, limiting
SO<INF>2</INF> emissions to 0.80 lb/MMBtu and particulate matter
emissions to 0.10 lb/MMBtu, constituted existing effective
controls.\148\
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\146\ Id., page 10.
\147\ Id., page 5-6.
\148\ Idaho 2022 plan submission, page 80.
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We note that as part of the September 27, 2024, supplement, Idaho
obtained and submitted additional information from the facility
assessing fuel usage and limits for the No. 4 power boiler.\149\ The
facility stated that to meet existing permitted NO<INF>X</INF> and
SO<INF>2</INF> limits, fuel oil is restricted to approximately 4-5% of
annual MMBtu consumption. Upon review of the supplemental facility
information, Idaho determined that it is not feasible to switch to low-
sulfur fuel oil, because the use of fuel oil is limited.\150\
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\149\ Idaho 2022 plan submission, Appendix B. as supplemented by
Idaho 2024 supplemental submission, Appendix F. Federal Land
Managers Consultation Comments and DEQ Responses (Append), page 35.
\150\ Id.
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The State also considered the time necessary for installing the
retrofit controls, energy and non-air quality environmental impacts of
the controls, and remaining useful life of control technologies.\151\
Idaho estimated that each of the technologically feasible
NO<INF>X</INF> and SO<INF>2</INF> controls would take 32 months to
implement. Idaho also noted that operation of the NO<INF>X</INF> and
SO<INF>2</INF> controls would increase energy demand at the
facility.\152\ Idaho also indicated that a wet scrubber would increase
the amount of water used, and LoTOx would increase the amount of
nitrates in the facility's wastewater. Regarding remaining useful life
of the controls, Idaho indicated the controls would have a lifetime of
20 years.\153\
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\151\ Idaho 2022 plan submission, Appendix B. Four-Factor
Analyses and Reviews. Clearwater Paper Corp.--Pulp and Paperboard
Division, pages 7-9.
\152\ Id.
\153\ Id.
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Idaho submitted the permit conditions that implement the existing
NO<INF>X</INF> and SO<INF>2</INF> limits along with the associated
monitoring, recordkeeping, and reporting requirements and compliance
schedule for incorporation by reference into the Idaho SIP at 40 CFR
52.670(d).\154\ See Table 6 of this preamble.
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\154\ Each control measure necessary for reasonable progress is
to be submitted in a form that is enforceable as a practical matter.
The practically-enforceable provisions are then incorporated by
reference into the CFR to be made enforceable by the EPA and
citizens. See 57 FR 13497, April 16, 1992, at page 13567 (explaining
principles, including enforceability and accountability, to which
SIPs and implementing instruments must adhere to help assure that
planned emission reductions will be achieved); and 77 FR 74355,
December 14, 2012, at page 74365 (State's SIP must contain
monitoring, recordkeeping, and reporting components necessary to
make regional haze-related emission limitations enforceable).
---------------------------------------------------------------------------
iii. EPA Evaluation
Clearwater Paper: No. 4 and No. 5 Recovery Furnaces
For PM<INF>10</INF>, we concur with Idaho's determination that the
existing ESPs and associated emission limits to meet MACT requirements
constitute existing effective controls.\155\ As stated in the EPA 2019
Guidance on page 24, for a unit that complies with MACT, it is unlikely
that an analysis of control measures would conclude that even more
stringent control of PM is necessary to make reasonable progress.
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\155\ EPA 2019 Guidance, pages 23 and 24.
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For NO<INF>X</INF>, the EPA does not agree with the State's finding
that selective catalytic reduction (SCR), or low-temperature oxidation
(LoTOx) technologies would not be technically feasible because they had
not been used on the sources in question. In fact, the EPA has
frequently found that controls which have been demonstrated on one type
of source are feasible on another, related source.\156\ Nevertheless,
the EPA agrees with Idaho's ultimate conclusion that additional
controls are not necessary in this case because the current
NO<INF>X</INF> emission rate for the No. 4 recovery furnace (75 ppmvd
at 8% oxygen) appears commensurate with LAER for recovery furnaces.
Finally, we note that the No. 5 recovery furnace is subject to PSD BACT
limits.\157\
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\156\ See 89 FR 67341, August 20, 2024, at page 67360.
\157\ Idaho 2022 plan submission, page 80.
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Therefore, we agree with Idaho's determination that the existing
NO<INF>X</INF> controls on the No. 4 and No. 5 recovery furnaces are
necessary for reasonable progress. Accordingly, we propose to find that
the permit conditions submitted by Idaho for the No. 4 and No. 5
recovery furnaces are sufficient to make the above-described
PM<INF>10</INF> and NO<INF>X</INF> requirements enforceable as a
practical matter.\158\ We propose to approve and incorporate by
reference the permit conditions that implement the requirements and
associated monitoring, recordkeeping and reporting requirements and
compliance schedules specified in Table 6 of this preamble into the
Idaho SIP at 40 CFR 52.670(d).
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\158\ Idaho 2024 supplemental submission, Appendix J. Redacted
Permits and Attachments for Regional Haze (New), 1. Clearwater Paper
Corp.--Pulp and Paperboard Division Redacted Permits.
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Clearwater Paper: No. 4 Power Boiler
We have determined that Idaho adequately considered the four
statutory factors when determining the NO<INF>X</INF> and
SO<INF>2</INF> controls necessary for the No. 4 power boiler. Idaho
identified and evaluated a reasonable set of potential controls: three
SO<INF>2</INF> controls and five NO<INF>X</INF> controls, and Idaho
adequately estimated the cost-effectiveness of each of the feasible
controls, using vendor quotes or the EPA's Control Cost
[[Page 13531]]
Manual to estimate the cost-effectiveness of controls.\159\
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\159\ Idaho 2024 supplemental submission, appendix H, DEQ
Responses to Public Comments (Replace), page 41.
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After reviewing additional information submitted on fuel usage and
associated limits for SO<INF>2</INF>, we concur with Idaho's decision
that it is not feasible to require the facility to fire lower sulfur
fuel oil in the No. 4 power boiler at this time. Information in the
September 27, 2024, supplemental submission stated that the No. 4 power
boiler fires hog fuel and natural gas primarily, and while being
permitted to fire higher sulfur fuel oil, the facility must limit the
amount of fuel oil fired due to operational requirements and to ensure
compliance with the current 100 ton per year SO<INF>2</INF> emission
limit.\160\ The oil emissions are limited by the existing
NO<INF>X</INF> permit limit of 0.3 lb/MMBtu or 842 tpy for oil/wood and
the existing SO<INF>2</INF> permit limit of 0.80 lb/MMBtu or 100 tons
per any consecutive 12-month period.\161\ Additionally, there are
several monitoring, recordkeeping, and reporting requirements in the
existing permit that will ensure compliance with the existing
NO<INF>X</INF> and SO<INF>2</INF> emission limits.
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\160\ Idaho 2024 supplemental submission, appendix B, Clearwater
power boiler fuel oil analysis.
\161\ Ibid.
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The EPA concurs with Idaho's finding that the existing
NO<INF>X</INF> and SO<INF>2</INF> emission limits established pursuant
to the NSPS requirements for Fossil-Fuel-Fired Steam Generators in 40
CFR part 60, subpart D are necessary for reasonable progress. We also
find that the submitted permit conditions for the Clearwater Paper No.
4 Power Boiler are sufficient to make the existing NO<INF>X</INF> and
SO<INF>2</INF> requirements enforceable as a practical matter. We
propose to approve and incorporate by reference the permit conditions
that implement the existing requirements and associated monitoring,
recordkeeping and reporting requirements and compliance schedules
specified in Table 6 of this preamble into the Idaho SIP at 40 CFR
52.670(d).
b. ITAFOS (Idaho DEQ Facility ID 029-00003)
i. Background
ITAFOS Conda LLC produces fertilizer in Soda Springs, Idaho. The
East Sulfuric Acid Plant is a sulfur burning, dual-contact, dual-
absorption plant that produces sulfuric acid and steam for use in other
facility processes.\162\ The plant combusts elemental sulfur in air to
produce sulfur dioxide which is then passed through a series of four
catalyst beds to convert the sulfur dioxide into sulfur trioxide. The
primary pollutant emitted from this process is SO<INF>2</INF>.\163\ The
gas exiting the plant stack is continuously monitored for
SO<INF>2</INF>.\164\
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\162\ Idaho 2022 plan submission, appendix B, ITAFOS Four-Factor
Analysis Review, page 1.
\163\ Id.
\164\ Id., pages 1 and 2.
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ii. Idaho Control Determination
ITAFOS: East Sulfuric Acid Plant
Idaho evaluated retrofit SO<INF>2</INF> controls for the East
Sulfuric Acid Plant using the four statutory factors.\165\ In its
initial 2022 submission, Idaho submitted evaluations of five retrofit
SO<INF>2</INF> controls: wet flue gas desulfurization (WFGD), hydrogen
peroxide scrubber, dry sorbent injection (DSI), spray dry absorber
(SDA), and circulating dry scrubber (CDS). Idaho's 2022 submission
includes an evaluation of the technological feasibility of the
controls, cost-effectiveness of the controls, time necessary for
compliance, energy and non-air quality environmental impacts, and
remaining useful life of the retrofit controls.\166\ Idaho determined
that SDA and CDS were not technologically feasible because the
temperature of the exhaust gas in the East Sulfuric Acid Plant is too
low for the controls to effectively remove SO<INF>2</INF>.\167\
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\165\ Id., page 2.
\166\ Id., appendix B, ITAFOS Four-Factor Analysis Review, pages
3-6.
\167\ Id, page 3.
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In its 2022 submission, Idaho determined that WFGD, hydrogen
peroxide scrubbers, and DSI were technically feasible options for
SO<INF>2</INF> retrofit controls.\168\ Based on information obtained
from the company, Idaho calculated the cost-effectiveness of the three
technologically feasible controls. According to Idaho, WFGD was cost
effective at $4,100 per ton, hydrogen peroxide scrubbers at $4,777 per
ton, and DSI at $4,121 per ton.\169\
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\168\ Id., page 3. See table 2.
\169\ Id., pages 5 and 6.
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Idaho updated its evaluations of the three retrofit controls in its
September 27, 2024, supplemental submission.\170\ Idaho submitted
additional information obtained from the facility that impacted the
technologically feasibility and cost of certain retrofit controls. For
DSI, Idaho determined that the following factors rendered it
technologically infeasible: (1) physical constraints that would impact
the ability to install add-on DSI control equipment in the immediate
vicinity to the East Sulfuric Acid Plant stack; (2) concerns about how
the sorbent used in the control equipment could impact the existing
chemical process; and (3) added costs that Idaho did not consider in
its 2022 submission, including ancillary equipment needed to support
WFGD control technology.\171\
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\170\ Idaho 2024 supplemental submission, appendix B Four Factor
Analysis Reviews (Append).
\171\ Ibid.
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The revised cost estimates found that WFGD retrofit technology
would cost $6,270 per ton, hydrogen peroxide scrubbers would cost
$7,120 per ton, and DSI would cost $6,210 per ton.\172\ All of these
estimates were above the State-established cost-effectiveness
threshold. Idaho also included an additional updated cost calculation
for WFGD that further considered site-specific considerations.\173\
According to this update, WFGD had a cost-effectiveness of $7,976.\174\
Idaho ultimately determined that it would not require SO<INF>2</INF>
retrofit control technology to be installed and that the inherent plant
design (dual absorption contact process, vertical tube mist eliminator,
and cesium catalyst in the fourth bed of the converter) and compliance
with the NSPS standard for sulfur dioxide and acid mist (40 CFR part
60, subpart H) were necessary for reasonable progress.\175\
Specifically, the current operating permit requires, among other
things, that the owner or operator shall not cause to be discharged
into the atmosphere from the East Sulfuric Acid Plant any gases which
contain sulfur dioxide in excess of 2 kg per metric ton of acid
produced (4 pounds per ton), the production being expressed as 100%
sulfuric acid, in accordance with 40 CFR 60.82(a) (condition 5.7).\176\
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\172\ Id., pages 5 and 6.
\173\ Id., pages 7-8.
\174\ Id., page 10.
\175\ Ibid.
\176\ Ibid.
---------------------------------------------------------------------------
As part of the Idaho 2024 supplemental submission, Idaho submitted
the permit conditions that implement the existing SO<INF>2</INF>
requirements and associated monitoring, recordkeeping and reporting
requirements and compliance schedule for incorporation by reference
into the Idaho SIP at 40 CFR 52.670(d).\177\
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\177\ Each control measure necessary for reasonable progress is
to be submitted in a form that is enforceable as a practical matter.
The practically enforceable provisions are then incorporated by
reference into the CFR to be made enforceable by the EPA and
citizens. See 57 FR 13497, April 16, 1992, at page 13567 (explaining
principles, including enforceability and accountability, to which
SIPs and implementing instruments must adhere to help assure that
planned emission reductions will be achieved); and 77 FR 74355,
December 14, 2012, at page 74365 (State's SIP must contain
monitoring, recordkeeping, and reporting components necessary to
make regional haze-related emission limitations enforceable).
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[[Page 13532]]
iii. EPA Evaluation
ITAFOS: East Sulfuric Acid Plant
The EPA reviewed Idaho's evaluation of SO<INF>2</INF> controls at
the ITAFOS East Sulfuric Acid Plant in the states 2022 and 2024
submissions and has determined that the State selected potential
retrofit controls, evaluated the technological and economic feasibility
of the retrofit controls, and adequately considered each of the
statutory factors when determining the controls necessary for
reasonable progress.\178\
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\178\ EPA 2019 Guidance, page 37 (``We anticipate that the
outcome of the decision-making process by a state regarding a
control measure may most often depend on how the state assesses the
balance between the cost of compliance and the visibility benefits,
with the other three statutory factors either being subsumed into
the cost of compliance or not being major considerations.'').
---------------------------------------------------------------------------
Regarding technological feasibility, Idaho provided a valid basis
to determine CDS and ammonia packed-bed scrubber were not feasible. For
DSI and WFGD, the EPA does not agree that the factors Idaho cites
render these options technologically infeasible. DSI and WFGD are
common retrofit SO<INF>2</INF> controls that have proven effective in
multiple applications. The need to construct baghouses, absorbing
towers, and extended ductwork is not uncommon. These are factors the
vendor should take into consideration in designing the system for a
particular application. The EPA does recognize, however, that these
same factors necessarily impact the cost of the controls and may impact
the control efficiency.
With respect to cost calculations, the EPA recommended in the EPA
2019 Guidance that States follow the EPA's Control Cost Manual
recommendations to ensure consistent cost calculations across controls
and sources.\179\ The EPA also recommended that States explain any
deviations or alternative approaches.\180\ Finally, the Control Cost
Manual provides for generic cost estimates using a consistent
methodology, but recommends States obtain facility-specific vendor cost
quotes when practical.\181\
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\179\ EPA 2019 Guidance, page 32.
\180\ Id.
\181\ Id.
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In evaluating the cost of WFGD, a hydrogen peroxide scrubber, and
DSI, Idaho obtained cost information from equipment vendors.\182\ Idaho
conducted subsequent evaluations of its initial cost estimates to
ensure the cost estimates took into consideration all the ancillary
equipment necessary and site specific complexities. Idaho adequately
explained its cost calculation methodology, its use of the Control Cost
Manual, and its rationale for adjusting initial vendor estimates based
on site-specific information. Therefore, based on the State's
consideration of the four statutory factors, we agree with Idaho's
determinations that additional SO<INF>2</INF> controls on the East
Sulfuric Acid Plant are not necessary for reasonable progress.
---------------------------------------------------------------------------
\182\ Idaho 2024 supplemental submission, appendix B Four Factor
Analysis and Review (Append), page 5-10.
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We propose to approve and incorporate by reference the permit
conditions that implement the existing SO<INF>2</INF> requirements and
associated monitoring, recordkeeping and reporting requirements and
compliance schedules specified in Table 6 of this preamble into the
Idaho SIP at 40 CFR 52.670(d).
c. NWP-Soda Springs (Idaho DEQ Facility ID 007-00008)
i. Background
Northwest Pipeline--Soda Springs (NWP) is a natural gas compressor
station located near Soda Springs, Idaho. The compressor station
operates remotely and is used to compress and transmit natural gas
along the transmission pipeline.\183\ The facility has four natural
gas-fired lean-burn reciprocating internal-combustion engines (RICE)
(three TLA-6 IC engines and one TCVA-16 IC engine) that utilize air/
fuel ratio controls and ignition timing delay to control NO<INF>X</INF>
emissions.\184\
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\183\ Idaho 2022 plan submission, page 66.
\184\ Ibid.
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ii. Idaho Control Determination
NWP--Soda Springs: RICE Engines
Idaho evaluated the RICE engines for NO<INF>X</INF> controls.\185\
The facility identified seven available retrofit NO<INF>X</INF> control
technologies for the four RICE engines: air/fuel ratio controls,
ignition timing delay, SCR, SNCR, NSCR, electrification, and low
emission combustion retrofit (LEC).\186\ Upon review, the facility
concluded that LEC was the only technically feasible retrofit
technology available and developed cost estimates.\187\ Idaho estimated
that the LEC retrofit would reduce NO<INF>X</INF> emissions by
87%.\188\ The Idaho DEQ reviewed the facility's cost estimates for LEC,
adjusted certain aspects, including the interest rate used and
equipment life, and concluded such a retrofit would cost $10,656 per
ton removed for the TCVA-16 IC engine and $24,874 per ton removed for
the TLA-6 IC engines, exceeding the State-established cost-
effectiveness threshold.\189\
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\185\ Idaho 2022 plan submission, appendix B, Four-Factor
Analyses Reviews, 4 Northwest Pipeline.
\186\ Ibid.
\187\ Ibid.
\188\ Ibid.
\189\ Ibid.
---------------------------------------------------------------------------
Idaho also evaluated the time necessary for compliance, the energy
and non-air quality environmental impacts, and remaining useful life of
an LEC retrofit.\190\ Idaho estimated that such a retrofit would take
12 to 18 months to design and install. Idaho also indicated that the
LEC retrofit would increase electricity consumption. Idaho estimated
that the remaining lives of the engines were 20 years.
---------------------------------------------------------------------------
\190\ Ibid.
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Based on its review of the four factors, Idaho determined that the
LEC retrofit was not cost-effective. However, after the initial 2022
submission, Idaho entered into a compliance agreement schedule with the
facility to replace the four RICE engines with two gas-fired turbines
by July of 2031.\191\ All four RICE engines will be removed and
replaced with two gas-fired turbines, specifically a Solar Centaur 40-
4700S 15 ppm NO<INF>X</INF> unit and a Solar Taurus 70-10802S 9 ppm
NO<INF>X</INF> unit.\192\ Idaho determined that the replacements would
achieve a 98% reduction in NO<INF>X</INF>--based on potential to
emit.\193\
---------------------------------------------------------------------------
\191\ Idaho 2024 supplemental submission, appendix J. Redacted
Permits and Attachments for Regional Haze (New), Northwest Pipeline,
LLC, CAS dated September 1, 2023.
\192\ Ibid.
\193\ Idaho 2024 supplemental submission, page 10. Idaho
estimates the total reduction of NO<INF>X</INF> PTE upon completion
of the equipment upgrade project will be 1687.17 tpy.
---------------------------------------------------------------------------
Idaho determined the engine replacements were necessary for
reasonable progress and as part of the September 27, 2024, supplemental
submission, Idaho included the compliance agreement schedule for
incorporation by reference into the Idaho SIP at 40 CFR 52.670(d).\194\
See Table 6 of this preamble for details.
---------------------------------------------------------------------------
\194\ Each control measure necessary for reasonable progress is
to be submitted in a form that is enforceable as a practical matter.
The practically enforceable provisions are then incorporated by
reference into the CFR to be made enforceable by the EPA and
citizens. See 57 FR 13497, April 16, 1992, at page 13567 (explaining
principles, including enforceability and accountability, to which
SIPs and implementing instruments must adhere to help assure that
planned emission reductions will be achieved); and 77 FR 74355,
December 14, 2012, at page 74365 (State's SIP must contain
monitoring, recordkeeping, and reporting components necessary to
make regional haze-related emission limitations enforceable).
---------------------------------------------------------------------------
iii. EPA Evaluation
The EPA concurs that Idaho adequately considered the four statutory
[[Page 13533]]
factors in determining the control necessary for reasonable progress at
the NWP-Soda Springs facility. Accordingly, the EPA concurs with
Idaho's determination that the requirement to remove the four RICE
engines and replace them with two gas-fired turbines by July 31, 2031,
is necessary for reasonable progress.
We propose to approve and incorporate by reference the submitted
compliance agreement schedule specified in Table 6 of this preamble
into the Idaho SIP at 40 CFR 52.670(d).
d. P4 Productions LLC (P4) (Idaho DEQ Facility ID 029-00001)
i. Background
P4 Production LLC (P4) owns and operates an elemental phosphorus
manufacturing facility located in Soda Springs, Idaho, where phosphate
ore is nodulized in a rotary kiln.\195\ Emissions from the nodulizing
kiln are controlled by a dust knockout chamber, spray tower, four
parallel cyclonic separator pairs, four parallel Hydro-Sonic scrubbers
and demisters, and a lime concentrated dual alkali SO<INF>2</INF>
scrubbing system.\196\
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\195\ Idaho 2022 plan submission, page 70.
\196\ Id., appendix B. Four-Factor Analyses and Reviews, P4
Production LLC.
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ii. Idaho Control Determination
P4: Nodulizing Kiln
Idaho selected the nodulizing kiln for four-factor analysis for
NO<INF>X</INF>, PM<INF>10</INF>, and SO<INF>2</INF>.
For NO<INF>X</INF>, the facility identified the following potential
retrofit technologies: good combustion practices, low NO<INF>X</INF>
burners, SCR, and SNCR.\197\ However, all were eliminated by the
facility as technically infeasible. P4's primary rationale was the
temperature demands for sintering phosphate ore are inconsistent with
the temperature needs for the controls and that high particulate
loading would fowl the catalyst.\198\
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\197\ Ibid.
\198\ Ibid.
---------------------------------------------------------------------------
Idaho concurred that no technically feasible control technologies
were available. The nodulizing kiln is not subject to any existing
NO<INF>X</INF> controls or limits. Thus, Idaho did not determine that
existing NO<INF>X</INF> controls are necessary for reasonable progress.
However, to establish a NO<INF>X</INF> limit for the nodulizing kiln,
the Idaho DEQ entered into a compliance agreement schedule (CAS) with
the facility to establish a NO<INF>X</INF> emission limit for the
nodulizing kiln.\199\ The CAS requires the facility to submit a
performance test protocol for approval by the Idaho DEQ, conduct
testing over 12 months, submit a NO<INF>X</INF> emissions test report
for approval by the Idaho DEQ, and submit a permit application to
include a new NO<INF>X</INF> emission limit.\200\
---------------------------------------------------------------------------
\199\ Idaho 2024 supplemental submission, page 11-12.
\200\ Idaho 2024 supplemental submission, Appendix J. Redacted
Permits and Attachments for Regional Haze (New), 5. P4 Production
LLC Redacted Permit and Compliance Agreement Schedule.
---------------------------------------------------------------------------
For PM<INF>10</INF>, the facility reviewed four retrofit control
technologies: good combustion practices, ESP, fabric filters, and wet
scrubbers. Of these alternatives, wet scrubbers and wet ESPs were
identified as technically feasible.\201\ P4 Production already employs
a Venturi wet scrubber system to control PM<INF>10</INF> emissions from
the nodulizing kiln.\202\ Idaho estimated that the existing wet
scrubber system achieves 95% PM<INF>10</INF> control and concluded that
it is the most effective control for PM<INF>10</INF>.\203\ Idaho
determined that the current Venturi wet scrubber system constituted
existing effective controls for the nodulizing kiln. In the 2024
submission, Idaho included the permit conditions establishing
PM<INF>10</INF> emissions limits reflecting operation of the Venturi
wet scrubber system.\204\
---------------------------------------------------------------------------
\201\ Idaho 2022 plan submission, appendix B, Four-Factor
Analyses and Reviews, P4 Production LLC.
\202\ The kiln also include a dust knockout chamber, a spray
tower, four parallel Hydro-Sonic systems, eight parallel cyclonic
separator, and four mist eliminators that each provide
PM<INF>10</INF> control.
\203\ Idaho 2022 plan submission, Appendix B. Four-Factor
Analyses and Reviews, P4 Production LLC.
\204\ Idaho 2024 supplemental submission, Appendix J. Redacted
Permits and Attachments for Regional Haze (New), 6. P4 Production
LLC Redacted Permit.
---------------------------------------------------------------------------
For SO<INF>2</INF>, the facility currently employs a lime
concentrate dual alkali (LCDA) system that achieves 97% SO<INF>2</INF>
emissions reductions.\205\ Idaho identified process controls and flue
gas desulfurization (FGD) as potential retrofit controls, however the
Idaho ultimately determined these were either technically infeasible or
would not achieve greater emissions reductions than the existing LCDA
system. Thus, Idaho determined that the existing LCDA system
constituted existing effective controls for SO<INF>2</INF>. In the 2024
submission, Idaho included permit conditions establishing
SO<INF>2</INF> emissions limits reflecting operation of the LCDA
system.\206\
---------------------------------------------------------------------------
\205\ Id.
\206\ Idaho 2024 supplemental submission, Appendix J. Redacted
Permits and Attachments for Regional Haze (New), 6. P4 Production
LLC Redacted Permit.
---------------------------------------------------------------------------
iii. EPA Evaluation
P4: Nodulizing Kiln
Idaho adequately considered the four statutory factors in
determining the controls necessary for reasonable progress at P4 and
adequately determined that there are no additional NO<INF>X</INF>
controls that are feasible. Given that there is no current limit on
NO<INF>X</INF> emissions from the nodulizing kiln, the EPA agrees that
existing NO<INF>X</INF> controls are not necessary for reasonable
progress. The CAS will assist Idaho is establishing a NO<INF>X</INF>
emissions limit and thus: (1) help prevent future visibility
impairment; and (2) assist the State in future regional haze planning
efforts. The CAS includes a detailed timeline for testing, developing,
and implementing a NO<INF>X</INF> emission limit along with agreed upon
methods, with associated monitoring and recordkeeping requirements.
Therefore, the EPA is proposing to approve the CAS and incorporate it
into Idaho's SIP as a SIP strengthening measure.
The EPA concurs with Idaho's determination that no new
SO<INF>2</INF> controls are reasonable and the current LCDA system and
associated SO<INF>2</INF> emission limit (143 lb/hr) are necessary for
reasonable progress. The facility underwent a BACT review under PSD in
2009 for SO<INF>2</INF> and, consistent with the EPA 2019 Guidance, the
EPA agrees that additional control technology review under the four
regional haze factors is unlikely to find feasible, cost-effective
controls. \207\ Idaho's submissions indicate that the existing system
is the best SO<INF>2</INF> control for the kiln.
---------------------------------------------------------------------------
\207\ EPA 2019 Guidance, page 23. Idaho 2022 plan submission,
Appendix B. P4 Production LLC.
---------------------------------------------------------------------------
For PM<INF>10</INF>, the EPA concurs with Idaho's finding that the
existing Venturi scrubbing system and associated PM<INF>10</INF>
emission limit (30.0 lb/hr) constitute existing effective controls that
are necessary for reasonable progress. Idaho's submission indicates
that this system achieves at least 95% PM<INF>10</INF> emissions
reductions.
We propose to find that the submitted permit conditions for the
existing PM<INF>10</INF> and SO<INF>2</INF> controls are sufficient to
make the existing requirements enforceable as a practical matter. We
propose to approve and incorporate by reference the CAS and permit
conditions specified in Table 6 of this preamble into the Idaho SIP at
40 CFR 52.670(d).
e. Simplot (Idaho DEQ Facility ID 077-00006)
i. Background
The J.R. Simplot Company owns and operates a phosphate fertilizer
[[Page 13534]]
manufacturing plant, in Pocatello, Idaho (the Don Siding Plant).
Elemental sulfur is brought to the plant, processed into sulfur
trioxide, then passed through an absorber containing 93% sulfuric acid
to allow absorption of sulfur trioxide to form more concentrated
sulfuric acid.\208\ This process is called ``single contact'' and is
employed by the No. 300 Sulfuric Acid Plant at the Don Siding Plant.
The No. 400 Sulfuric Acid Plant uses an additional converter to oxidize
SO<INF>2</INF> to sulfur trioxide which, passes through a final
absorber, called a ``double contact'' process.\209\
---------------------------------------------------------------------------
\208\ Idaho 2022 plan submission, Appendix B. J.R. Simplot
Company-Don Siding.
\209\ Ibid.
---------------------------------------------------------------------------
The No. 300 Sulfuric Acid Plant includes a DynaWave reverse-jet
scrubber and an Ammsox scrubber, in series, to reduce SO<INF>2</INF>
emissions and mist eliminators are installed on the Ammsox scrubber to
reduce potential PM<INF>10</INF> emissions.\210\ The double-contact
process used by the No. 400 sulfuric acid plant is more efficient at
collecting SO<INF>2</INF> (as sulfuric acid) than the single contact
process, and, as a result, no additional controls are installed on the
No. 400 Sulfuric Acid Plant.\211\
---------------------------------------------------------------------------
\210\ Ibid.
\211\ Ibid.
---------------------------------------------------------------------------
ii. Idaho Control Determination
Idaho selected the No. 300 and No. 400 Sulfuric Acid Plants for
four-factor analysis, specifically, to evaluate PM<INF>10</INF> and
SO<INF>2</INF> controls for the No. 300 Sulfuric Acid Plant and
NO<INF>X</INF> and SO<INF>2</INF> controls for the No. 400 Sulfuric
Acid Plant. Idaho determined that there were existing effective
SO<INF>2</INF> controls on both plants and therefore only reviewed
PM<INF>10</INF> controls for the No. 300 Sulfuric Acid Plant and
NO<INF>X</INF> controls for the No. 400 Sulfuric Acid Plant.
Specifically, the plants are already subject to BACT-level
SO<INF>2</INF> limits as established by Federal Consent Decree on
December 3, 2015.\212\ The SO<INF>2</INF> requirements are listed in
Table 6 of this preamble.
---------------------------------------------------------------------------
\212\ Ibid.
---------------------------------------------------------------------------
The Federal Consent Decree establishes SO<INF>2</INF> limits for
both the No. 300 and No. 400 Sulfuric Acid Plants to resolve
differences surrounding PSD applicability.\213\ Idaho determined that
these Consent Decree limits constitute existing effective controls for
SO<INF>2</INF> for both plants.\214\ The Idaho DEQ incorporated these
Consent Decree limits \215\ and associated monitoring, recordkeeping,
and reporting requirements into the facility's operating permit and
into Idaho's SIP at 40 CFR 51.670(d). As part of its 2024 supplemental
submission, Idaho submitted additional permit conditions limiting the
SO<INF>2</INF> emissions from the No. 300 and No. 400 Sulfuric Acid
Plants.
---------------------------------------------------------------------------
\213\ See <a href="https://www.epa.gov/enforcement/consent-decree-j-r-simplot-company/">https://www.epa.gov/enforcement/consent-decree-j-r-simplot-company/</a>.
\214\ Idaho 2024 supplemental submission, Appendix J. Redacted
Permits and Attachments for Regional Haze, 3. J.R. Simplot Company-
Don Siding Plant Redacts Permit.
\215\ For the No. 300 Sulfuric Acid Plant: SO<INF>2</INF>
emissions not to exceed 2.5 lb/ton of 100% sulfuric acid produced on
a rolling 3-hour average basis, except during periods of startup,
shutdown, or malfunction; and SO<INF>2</INF> emissions not to exceed
1.5 lb/ton 100% sulfuric acid produced on a rolling 365-day average
basis including periods of startup, shutdown, or malfunction. For
the No. 400 Sulfuric Acid Plant: SO<INF>2</INF> emissions not to
exceed 2.5 lb/ton of 100% sulfuric acid produced on a rolling 3-hour
average basis, except during periods of startup, shutdown, or
malfunction; and SO<INF>2</INF> emissions not to exceed 1.6 lb/ton
100% sulfuric acid produced on a rolling 365-day average basis
including periods of startup, shutdown, or malfunction.
---------------------------------------------------------------------------
Simplot: No. 300 Sulfuric Acid Plant
For PM<INF>10</INF>, the facility identified five control
technologies, three of which were found to be technically feasible:
mist eliminators, wet ESP, and wet scrubbers.\216\ The facility already
employs mist eliminators and a wet scrubber. Idaho determined that
fabric filters were infeasible because particulate matter emissions
from the plant are in liquid form and fabric filters are designed to
remove particulate matter from a gas stream. Idaho also determined that
cyclones were infeasible because they are designed to collect coarse-
to-medium-sized particulate matter from gas streams, and particulate
emissions from the plant are primarily less than 10 micrometers in
diameter. Idaho evaluated the cost-effectiveness of the remaining
control: wet ESP. Simplot provided Idaho with a vendor quote to
determine the capital cost of the wet ESP as well as site-specific
information bearing on the difficulty of retrofitting the No. 300
Sulfuric Acid Plant.\217\ Based on this information, Idaho determined
that installing a wet ESP would cost $39,721 per ton PM<INF>10</INF>
removed, exceeding the State-established cost-effectiveness
threshold.\218\ Idaho also considered the time to install the wet ESP,
the energy and non-air quality environmental impacts, and remaining
useful life of the wet ESP.\219\ Based on consideration of the four
statutory factors, Idaho determined that installing a wet ESP on the
No. 300 Sulfuric Acid Plant was not necessary for reasonable progress.
Therefore, Idaho determined that the existing mist eliminators and wet
scrubbers were necessary for reasonable progress. The plant is already
subject to a PM<INF>10</INF> emissions limit of 11.4 lbs/hr.\220\
---------------------------------------------------------------------------
\216\ Ibid.
\217\ Ibid.
\218\ Ibid.
\219\ Ibid.
\220\ 40 CFR 52.670(d); See Operating Permit T1-2017-0024,
condition 15.9.
---------------------------------------------------------------------------
Simplot: No. 400 Sulfuric Acid Plant
According to Idaho's 2022 submission, the NO<INF>X</INF> emission
from sulfuric acid plants is intrinsically limited because the flame
temperature of sulfur is too low to thermally create
NO<INF>X</INF>.\221\ According to the 2022 submission, the No. 400
Sulfuric Acid Plant emits 10 ppmv NO<INF>X</INF>, dry basis at 3
percent oxygen. Nevertheless, Idaho requested Simplot evaluate
additional NO<INF>X</INF> controls. The facility identified six
technologies for the control of NO<INF>X</INF> at the No. 400 Sulfuric
Acid Plant: flue gas recirculation (FGR), low NO<INF>X</INF> burners
(LNBs), ultra-low NO<INF>X</INF> burners (ULNBs), SCR, SNCR, and
SNCR.\222\ Based on information provided by Simplot, Idaho determined
that each of these retrofit controls were technically infeasible. The
primary reasons identified in Idaho's technological infeasibility
determinations were that the exhaust gas temperature is too low for
NO<INF>X</INF> catalysts to function and that LNB technology requires
low excess air to work.\223\
---------------------------------------------------------------------------
\221\ Idaho 2022 plan submission, Appendix B. J.R. Simplot
Company-Don Siding.
\222\ Ibid.
\223\ Ibid.
---------------------------------------------------------------------------
The facility proposed to retain the current design and operation of
the No. 400 Sulfuric Acid Plant, stating that the most recent
NO<INF>X</INF> stack test yielded a result of 10 ppmv, dry basis at 3
percent oxygen, which it found to be comparable to the NO<INF>X</INF>
concentration in the exhaust of natural gas-fired combustion unit
equipped with LNBs or ULNBs.\224\
---------------------------------------------------------------------------
\224\ Ibid.
---------------------------------------------------------------------------
iii. EPA Evaluation
The EPA concurs with Idaho's determination that the SO<INF>2</INF>
limits for the No. 300 and No. 400 Sulfuric Acid Plants are existing
effective controls. In the EPA 2019 Guidance, the EPA acknowledged that
a control technology review under the four regional haze factors was
unlikely to find feasible, cost-effective controls for sources that
recently went through PSD BACT.\225\ In this instance, both plants are
subject to 2015 BACT limits imposed through a Federal Consent Decree
with the EPA. Consistent with the EPA 2019 Guidance, and based on the
submitted information, the EPA agrees that additional control
technology review under the four
[[Page 13535]]
regional haze factors is unlikely to find feasible, cost-effective
controls.\226\
---------------------------------------------------------------------------
\225\ 2019 EPA Guidance, pages 22--23.
\226\ Ibid.
---------------------------------------------------------------------------
For PM<INF>10</INF> emissions, we concur with Idaho's determination
that the existing controls on the No. 300 Sulfuric Acid Plant are
necessary for reasonable progress and no additional controls are
necessary. Idaho considered the four statutory factors in making its
determination. Idaho's rationale for dismissing the fabric filter and
cyclone as technologically infeasible are sound. The EPA also agrees
with Idaho's determination that existing PM<INF>10</INF> measures are
necessary for reasonable progress for the regional haze second
implementation period. The No. 300 Sulfuric Acid Plant is subject to
PM<INF>10</INF> emissions limits (11.4 lb/hr (24-hr average) and 49.8
tpy (tons per any consecutive 12-month period)) for purposes of
nonattainment reasonable available control technology (RACT).
For NO<INF>X</INF> emissions, we concur with Idaho's determination
that the existing NO<INF>X</INF> emission limits are necessary for
reasonable progress and that no additional controls are necessary.
Idaho adequately evaluated the feasibility of additional emissions
controls. Idaho's justifications for determining these controls are
technologically infeasible are sound. We also note that Idaho imposed
the current NO<INF>X</INF> limit on the No. 400 Sulfuric Acid Plant to
meet nonattainment RACT requirements as part of the Portneuf Valley
PM<INF>10</INF> attainment plan (71 FR 39574, July 13, 2006).
NO<INF>X</INF> emissions are limited to 44.3 tpy based on any
consecutive 12-month period and 10.1 lb/hr (24-hour average) for
purposes of RACT. These limits are already incorporated into Idaho's
SIP.
We propose to approve and incorporate by reference the permit
conditions that implement Idaho's reasonable progress determinations
and associated monitoring, recordkeeping and reporting requirements and
compliance schedules specified in Table 6 of this preamble into the
Idaho SIP at 40 CFR 52.670(d).
f. Tamarack Mill (Idaho DEQ Facility ID 003-00001)
i. Background
The Tamarack Mill, LLC dba Evergreen Forest and Tamarack Energy
Partnership manufactures dry kiln lumber in New Meadows, Idaho.\227\
The sawmill processes logs into green dimensional lumber to be kiln-
dried. Wood waste is burned in the Riley Cogeneration Boiler to produce
steam to power a turbine (generating electricity for the regional power
grid) and to heat lumber drying kilns. The Riley Cogeneration Boiler,
rated at 102 MMBtu, operates with an existing multi-clone and wet
scrubber installed for PM<INF>10</INF> control, and no add-on
NO<INF>X</INF> control technology.\228\
---------------------------------------------------------------------------
\227\ Idaho 2022 plan submission, Appendix B. Tamarack Mill, LLC
dba Evergreen Forest and Tamarack Energy Partnership.
\228\ Ibid.
---------------------------------------------------------------------------
ii. Idaho Control Determination
Tamarack Mill: Riley Cogeneration Boiler
Idaho selected the Riley Cogeneration Boiler for PM<INF>10</INF>
and NO<INF>X</INF> analysis. For PM<INF>10</INF>, the facility already
employs multi-clone and wet scrubbers. Per Idaho's request, the
facility evaluated ESPs and baghouse or filter cartridge dust collector
technologies. Based on information provided by the facility, Idaho
determined that the baghouse or filter dust collector systems were
technically infeasible due to exhaust temperature and fire risk.\229\
Idaho determined that an ESP retrofit had a cost-effectiveness of
$13,114 per ton PM<INF>10</INF> reduced.\230\
---------------------------------------------------------------------------
\229\ Ibid.
\230\ Ibid.
---------------------------------------------------------------------------
Idaho also considered the time necessary to install the ESP and
determined it would take 2.5 years. With respect to energy and non-air
quality environmental impacts, Idaho noted that the ESP would increase
fire risk and the risk of concentrating hazardous metals. Finally,
Idaho determined the remaining useful life of the ESP would be 15
years. However, Idaho used a 30-year equipment life for consistency
across sources. Thus, Idaho determined that the ESP retrofit was not
necessary for reasonable progress in the second implementation period.
Based on its consideration of these factors, Idaho determined that the
existing PM<INF>10</INF> controls were necessary for reasonable
progress. Accordingly, Idaho submitted conditions from the Tamarack
Mill's operating permit that limit PM<INF>10</INF> emissions from the
source. Under the permit PM<INF>2.5</INF>/PM<INF>10</INF> emissions are
not to exceed 18 lb/hr and particulate matter emissions not to exceed
0.080 gr/dscf at 8 percent oxygen.\231\
---------------------------------------------------------------------------
\231\ Ibid.
---------------------------------------------------------------------------
For NO<INF>X</INF>, the facility identified SCR, LNB, FGR, and SNCR
as potential retrofit technology for the Riley Cogeneration Boiler.
Based on information provided by the facility, Idaho concluded that
SNCR was the only commercially available retrofit technology for wood
waste-fired boilers and estimated it would cost $10,855 per ton
NO<INF>X</INF> reduced to retrofit with SCNR.\232\ Idaho thus
determined that that an SNCR retrofit would exceed the State-
established cost-effectiveness threshold of $6,100 per ton.
---------------------------------------------------------------------------
\232\ Idaho 2024 supplemental submission, Appendix J. Redacted
Permits and Attachments for Regional Haze (New), 7. Tamarack Mill,
LLC dba Evergreen Forest and Tamarack Energy Partnership Redacted.
---------------------------------------------------------------------------
Idaho also considered the time necessary to install SNCR, its
energy and non-air quality environmental impacts, and remaining useful
life. Idaho determined it would take 1.5 years to install. Idaho also
indicated that installing SNCR would increase energy demand. Finally,
Idaho determined the system would last 15 years, but used a 30-year
lifetime for the purposes of its cost calculations. Based on its
consideration of these factors, Idaho determined that SNCR was not
necessary for reasonable progress. Idaho determined that the existing
NO<INF>X</INF> limits were necessary for reasonable progress.
Accordingly, Idaho submitted conditions from the Tamarack Mill's
operating permit that limit NO<INF>X</INF> emissions from the source.
The permit limits NO<INF>X</INF> emissions from the Riley Cogeneration
Boiler to 22.44 lb/hr and requires the facility to burn wood waste
only.\233\
---------------------------------------------------------------------------
\233\ Ibid.
---------------------------------------------------------------------------
iii. EPA Evaluation
For PM<INF>10</INF>, the EPA concurs with Idaho's determination
that the existing controls on the Riley Cogeneration Boiler are
necessary for reasonable progress and that no additional controls are
necessary. We note that the Riley Cogeneration Boiler already employs
effective emissions controls. According to Idaho's 2022 submission, the
2018 actual emissions from the Riley Cogeneration Boiler were 28.2 tons
PM<INF>10</INF>.\234\ Idaho's rationale for determining that the
baghouse and filter dust collector systems are infeasible are sound.
The EPA also agrees that Idaho adequately considered the four statutory
factors when determining that installing a wet ESP was not necessary
for reasonable progress for the second implementation period.
---------------------------------------------------------------------------
\234\ Ibid.
---------------------------------------------------------------------------
For NO<INF>X</INF>, the EPA agrees with Idaho's determination that
existing NO<INF>X</INF> limits are necessary for reasonable progress
and that no additional controls are necessary. Idaho's rationale for
determining that all NO<INF>X</INF> controls except SNCR are
technologically infeasible are sound. Moreover, Idaho adequately
considered the four statutory factors in determining that installing
SNCR is not necessary for reasonable progress during the second
[[Page 13536]]
implementation period. The EPA also notes that, according to Idaho's
2022 submission, 2018 actual emissions from the Riley Cogeneration
Boiler were relatively low, at 69.2 tons per year.
After reviewing the Idaho 2024 supplemental submission, we propose
to find that the permit conditions submitted for the Riley Cogeneration
Boiler are sufficient to make the existing PM<INF>10</INF> and
NO<INF>X</INF> requirements enforceable as a practical matter.\235\ We
propose to approve and incorporate by reference the permit conditions
that implement the requirements and associated monitoring,
recordkeeping and reporting requirements and compliance schedules
specified in Table 6 of this preamble into the Idaho SIP at 40 CFR
52.670(d).
---------------------------------------------------------------------------
\235\ Ibid.
---------------------------------------------------------------------------
g. TASCO--Nampa (Idaho DEQ Facility ID 027-00010)
i. Background
The Amalgamated Sugar Company (TASCO) operates a beet sugar
manufacturing plant in Nampa, Idaho that processes sugar beets into
refined sugar. TASCO--Nampa includes the Riley Boiler. The Riley Boiler
is a wall-fired, pulverized coal and natural gas-fired boiler with a
maximum heat input rating of 358 MMBtu/hr, fires low-sulfur bituminous
coal or natural gas.\236\ It is equipped with a high efficiency fabric
filter baghouse for particulate matter control.
---------------------------------------------------------------------------
\236\ Idaho 2022 plan submission, Appendix B. Four-Factor
Analyses and Reviews, The Amalgamated Sugar Company--Nampa.
---------------------------------------------------------------------------
ii. Idaho Control Determination
TASCO--Nampa: Riley Boiler
Idaho selected the Riley Boiler for four-factor analysis for
PM<INF>10</INF>, SO<INF>2</INF>, and NO<INF>X</INF>.\237\ We note that
the Riley Boiler is subject to BART for the first regional haze
implementation period originally approved by the EPA on June 22, 2011
(76 FR 36329). The EPA approved revisions to the BART determination for
the Riley Boiler on April 28, 2014 (79 FR 23273). The SIP-approved BART
emissions limits for the Riley Boiler are: 12.4 lbs/hr PM<INF>10</INF>
operating a baghouse and 103 lbs/hr NO<INF>X</INF> using LNBs.
---------------------------------------------------------------------------
\237\ Idaho 2024 supplemental submission, Appendix J. Redacted
Permits and Attachments for Regional Haze (New), 8. The Amalgamated
Sugar Company--Nampa Redacted Permit.
---------------------------------------------------------------------------
For PM<INF>10</INF>, per Idaho's request, the facility reviewed dry
and wet ESPs, wet scrubbers, and mechanical collectors including
cyclones and multi-clones.\238\ Based on information provided by TASCO,
Idaho determined that all controls are technically feasible but
asserted mechanical collectors and wet gas scrubbers are inferior to
fabric filter baghouses and dry ESPs, and also asserted that
retrofitting the boiler with an ESP was unlikely to reduce PM emissions
by more than a small amount.\239\
---------------------------------------------------------------------------
\238\ Idaho 2022 plan submission, Appendix B. Four-Factor
Analyses and Reviews, The Amalgamated Sugar Company--Nampa.
\239\ Ibid.
---------------------------------------------------------------------------
Therefore, Idaho determined that the most effective PM control
device (a fabric filter baghouse) was already being employed on the
Riley Boiler. Additionally, the facility asserted that none of the
retrofit control options would reduce PM<INF>10</INF> emissions below
that achieved when firing natural gas.\240\
---------------------------------------------------------------------------
\240\ Ibid.
---------------------------------------------------------------------------
For SO<INF>2</INF> and NO<INF>X</INF>, the Idaho DEQ evaluated
several SO<INF>2</INF> and NO<INF>X</INF> retrofit controls. These
included DSI and WFGD for SO<INF>2</INF> and LNB, SCR, and SNCR for
NO<INF>X</INF>. Idaho determined these controls were technically
feasible and the cost of several of the controls were less than the
State-established cost-effectiveness threshold of $6,100.\241\ Idaho
also considered the time necessary to install the controls, the energy
and non-air quality environmental impacts of the controls, and the
remaining useful life of the controls.\242\
---------------------------------------------------------------------------
\241\ Ibid.
\242\ Ibid.
---------------------------------------------------------------------------
As part of its original 2022 submission, Idaho did not evaluate
mandating that TASCO discontinue firing coal in the Riley Boiler.
However, on June 2, 2022, the facility submitted a letter to the Idaho
DEQ committing to discontinue the use of coal in the Riley Boiler at
the TASCO--Nampa facility. The Idaho DEQ determined that the Riley
Boiler fuel switch to combust only natural gas represented the greatest
potential reduction in emissions (1,171.5 tons per year of combined
NO<INF>X</INF>, SO<INF>2</INF>, and PM<INF>10</INF>) of all cost-
effective control options evaluated. Therefore, the Idaho DEQ
determined the fuel switch was necessary for reasonable progress and
submitted a revised permit P-2018.0011 issued February 15, 2023, where
it states, ``the Riley boiler shall be fired exclusively on natural gas
and no longer fire coal by July 1, 2027.'' \243\
---------------------------------------------------------------------------
\243\ Idaho 2024 supplemental submission, Appendix J. Redacted
Permits and Attachments for Regional Haze (New), 8. The Amalgamated
Sugar Company-Nampa Redacted Permit.
---------------------------------------------------------------------------
iii. EPA Evaluation
We concur with Idaho's determination that mandating the Riley
Boiler cease burning coal is necessary for reasonable progress. Idaho
evaluated a reasonable set of potential controls and considered the
four statutory factors in determining that discontinuing coal is
necessary for reasonable progress. We note that switching to
exclusively fire natural gas virtually eliminates PM<INF>10</INF>
emissions and SO<INF>2</INF> emissions. Switching to natural gas will
achieve a 99.9% reduction in SO<INF>2</INF> and 34% reduction in
NO<INF>X</INF> emissions. We acknowledge that installation of SCR on
the boiler could further reduce NO<INF>X</INF> emissions. However,
Idaho was not required under the Clean Air Act or Regional Haze Rule to
evaluate every potential control scenario.\244\ Here, Idaho was
reasonable in selecting the control that could achieve the aggregate
emissions reductions in haze-forming pollutants.
---------------------------------------------------------------------------
\244\ EPA 2019 Guidance, pages 28-29.
---------------------------------------------------------------------------
We propose to incorporate by reference the permit conditions that
implement the fuel switch requirement specified in Table 6 of this
preamble into the Idaho SIP at 40 CFR 52.670(d).
h. TASCO--Twin Falls (Idaho DEQ Facility ID 083-00001)
i. Background
The TASCO--Twin Falls facility processes sugar beets into refined
sugar and also produces animal feed products such as pulp and
betaine.\245\ The TASCO--Twin Falls facility has a coal-fired boiler, a
coal and natural gas-fired boiler, a natural gas fired boiler, a coal
or natural gas-fired pulp dryer, and several other minor emission
sources. The Foster Wheeler Boiler combusts only coal. The Babcock &
Wilcox (B&W) Boiler can combust both coal and natural gas. The Foster
Wheeler Boiler and B&W Boilers were both selected for four-factor
analysis for NO<INF>X</INF>, SO<INF>2</INF>, and PM<INF>10</INF>. The
B&W Boiler is a wall-fired, pulverized coal or natural gas-fired boiler
with a heat input rating of 268 million Btu per hour (mmBtu/hr).\246\
The boiler is equipped with voluntary low NO<INF>X</INF> burners for
coal that were not in the permit and a high efficiency fabric filter
baghouse for PM, PM<INF>10</INF>, and PM<INF>2.5</INF> control that is
listed in the permit as a control device.\247\ The facility's Foster
Wheeler Boiler is a moving grate stoker coal-fired boiler with a heat
input rating of 285 MMBtu/hr.\248\ The boiler fires low-sulfur
bituminous coal and is equipped with a high-efficiency fabric filter
baghouse for particulate matter control.\249\
---------------------------------------------------------------------------
\245\ Idaho 2022 plan submission, Appendix B, Regional Haze
Four-Factor Analysis Review--The Amalgamated Sugar Company LLC
(TASCO)--Twin Falls.
\246\ Ibid.
\247\ Ibid.
\248\ Ibid.
\249\ Ibid.
---------------------------------------------------------------------------
[[Page 13537]]
ii. Idaho Control Determination
TASCO--Twin Falls: B&W Boilers
Idaho selected the B&W Boilers (coal and natural gas-fired) for
four-factor analysis for NO<INF>X</INF>, SO<INF>2</INF>, and
PM<INF>10</INF>.\250\ For PM<INF>10</INF>, Idaho indicated that the B&W
Boiler is subject to the National Emission Standards for Hazardous Air
Pollutants for Major Sources: Industrial, Commercial, and Institutional
Boilers and Process Heaters, 40 CFR part 63, subpart DDDDD (boiler
MACT) limiting emissions of filterable PM, carbon monoxide, mercury,
and hydrochloric acid. Therefore, Idaho did not review additional PM
controls. As discussed in the following paragraphs, Idaho determined
that requiring TASCO to cease burning coal in the B&W Boiler and only
burn natural gas was necessary for reasonable progress.\251\ This
requirement reduces the PM<INF>10</INF> emissions by 11.08 tons per
year.\252\
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\250\ Ibid.
\251\ See permit T1-2016-0017.
\252\ Idaho 2024 supplemental submission, page 6.
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For NO<INF>X</INF>, based on information provided by TASCO, Idaho
identified two feasible controls: low NO<INF>X</INF> burners for coal
and SCR. Idaho determined that ultra-low NO<INF>X</INF> burners and
SNCR were not technically feasible due to the size of the firebox.\253\
Idaho reviewed low NO<INF>X</INF> burners and SCR under the four
statutory factors. Based on information provided by TASCO, Idaho
determined the cost-effectiveness of low NO<INF>X</INF> burners as
$2,900 per ton and SCR as $4,580 per ton. Idaho determined that it
would take 28 months to install SCR, that SCR would increase energy
demand and requires the use of ammonia, and that SCR would have a 20-
year remaining useful life.\254\ Idaho determined that requiring TASCO
to cease burning coal in the B&W Boiler and only burn natural gas was
necessary for reasonable progress.\255\ This requirement reduces the
NO<INF>X</INF> emissions by 126.39 tons per year.\256\
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\253\ Id.
\254\ Id.
\255\ See permit T1-2016-0017.
\256\ Idaho 2024 supplemental submission, page 6.
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For SO<INF>2</INF>, Idaho identified low sulfur coal, dry FGD,
WFGD, and DSI as feasible controls based on information from TASCO.
Idaho considered these controls under the four statutory factors. Idaho
determined the cost-effectiveness of each control as: $625 per ton for
low sulfur coal; $3,800 per ton for dry FGD, $3,810 per ton for WFGD,
and $4,580 per ton for DSI.\257\ Idaho estimated that the retrofit
SO<INF>2</INF> controls would take 36 months to install. Idaho also
indicated that the retrofit technologies may reduce the efficiency of
the boiler, dry FGD increase particulate emissions, and WFGD increases
water consumption and solid waste generation.\258\ Idaho determined
that the retrofit controls would have a remaining useful life of 20
years.\259\ Idaho determined that requiring TASCO to cease burning coal
in the B&W Boiler and only burn natural gas was necessary for
reasonable progress.\260\ This requirement reduces the SO<INF>2</INF>
emissions by 556.43 tons per year.\261\
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\257\ Id.
\258\ Id.
\259\ Id.
\260\ See permit T1-2016-0017.
\261\ Idaho 2024 supplemental submission, page 6.
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Idaho required TASCO to cease burning coal in the B&W Boiler as a
potential multi-pollutant control.\262\ Idaho determined that switching
to burning natural gas exclusively would reduce combined
NO<INF>X</INF>, SO<INF>2</INF>, and PM<INF>10</INF> emissions by 693.9
tons per year and have a cost-effectiveness of $1,128 per ton. The B&W
Boiler was already configured to fire natural gas, therefore no
additional time is needed to install controls.
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\262\ Id; See also Idaho 2022 plan submission, pages 69-70;
Idaho 2022 plan submission, Appendix B. Regional Haze Four-Factor
Analysis Review--The Amalgamated Sugar Company LLC (TASCO)--Twin
Falls.
Table 7--Comparison of Control Technologies for B&W Boiler at TASCO--Twin Falls \263\
----------------------------------------------------------------------------------------------------------------
Annual emission Cost-effectiveness
Pollutant Control option reduction (TPY) ($/ton)
----------------------------------------------------------------------------------------------------------------
NOX....................................... LNB natural gas.............. 196 2,900
NOX....................................... SCR.......................... 202.1 4,580
SO2....................................... Low Sulfur Bituminous Coal... 135.7 625
SO2....................................... Dry Sorbent Injection........ 278.3 4,580
SO2....................................... Wet FGD LSO.................. 540 5,270
SO2....................................... Dry FGD LSD.................. 528.8 5,040
NOX, SO2, PM10............................ Existing Primary Fuel 693.9 1,128
Replacement.
----------------------------------------------------------------------------------------------------------------
Based on the considerations discussed in the preceding paragraphs,
Idaho determined that removing coal as an allowable fuel in the B&W
Boiler was necessary for reasonable progress.\264\ On June 23, 2021,
the Idaho DEQ received a permit amendment application to remove coal as
a fuel option for the B&W Boiler, and the Idaho DEQ issued an amended
permit on July 22, 2021, for the fuel change from coal to natural
gas.\265\ According to Idaho, switching the B&W boiler to natural gas
resulted in a significant emissions reduction (694 tons per year of
combined NO<INF>X</INF>, SO<INF>2</INF>, and PM<INF>10</INF>) making it
the most effective control option evaluated.
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\263\ Idaho 2022 plan submission, page 69, table 34.
\264\ Idaho 2022 plan submission, pages 69-70.
\265\ Ibid.
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TASCO--Twin Falls: Foster Wheeler Boiler
Idaho selected the Foster Wheeler Boiler for four-factor analysis
for NO<INF>X</INF>, SO<INF>2</INF>, and PM<INF>10</INF>. For
PM<INF>10</INF>, Idaho noted in its 2022 submission that the Foster
Wheeler Boiler is subject to the NSPS for Fossil-Fuel-Fired Steam
Generators, 40 CFR part 60, subpart D, and the Boiler MACT, 40 CFR part
63, subpart DDDDD. Idaho also indicated that the boiler is equipped
with a fabric filter baghouse.\266\ In its 2022 submission, Idaho
determined that the existing baghouse constituted effective controls.
However, in its 2024 supplemental submission, Idaho required TASCO to
cease burning coal and only burn natural gas in the Foster Wheeler
Boiler.\267\ According to Idaho, the fuel switch obviated the need to
maintain the baghouse.\268\ According to the 2022 submission, the
decision to convert the Foster Wheeler Boiler to natural gas occurred
after Idaho had completed consideration of additional controls assuming
the boiler would continue to burn coal.\269\ Thus, Idaho's evaluation
of
[[Page 13538]]
additional controls is based on higher emission rates associated with
burning coal. Idaho submitted permit conditions requiring the fuel
switch for approval and incorporation into the SIP.
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\266\ Idaho 2022 plan submission, Appendix B. Regional Haze
Four-Factor Analysis Reviews, The Amalgamated Sugar Company--Twin
Falls.
\267\ Air Quality Tier I Operating Permit, Amalgamated Sugar
Company, T1-2016-0017.
\268\ Id.
\269\ Idaho 2022 plan submission, page 69.
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For NO<INF>X</INF>, based on information supplied by TASCO, Idaho
identified five technologies for consideration under the four statutory
factors: LNB, LNB and overfire air (OFA), LNB and flue gas
recirculation (FGR), SCR, and SNCR. Idaho rejected LNB and similar
burner controls as infeasible for stoker boilers. According to Idaho's
submissions, stoker boilers do not have an actual burner.\270\ Thus,
Idaho evaluated the cost, time necessary to install, energy and non-air
quality impacts, and remaining useful life of SCR and SNCR. As part of
the 2022 submission, Idaho did not evaluate a fuel switch to natural
gas because it would require a redesign of the boiler.\271\ Based on
information provided by TASCO, the cost-effectiveness of SNCR was
$5,180/ton of NO<INF>X</INF> reduced and SCR was $6,400/ton of
NO<INF>X</INF> reduced.\272\ TASCO also noted that SCR may not be
technically feasible for the Foster Wheeler Boiler, but did not
elaborate. Idaho adjusted the cost calculations provided by TASCO for
the purposes of consistency across units and sources. Based on these
adjustments, Idaho determined that the cost effectiveness of SNCR was
between $4,010 and $5,180/ton of NO<INF>X</INF> reduced and SCR was
between $3,780 and $6,400/ton of NO<INF>X</INF> reduced.\273\
Ultimately, Idaho determined that SNCR was the only cost-effective
NO<INF>X</INF> control option for the Foster Wheeler Boiler. According
to Idaho's submission, installation of SNCR would achieve annual
NO<INF>X</INF> emissions reductions of 90.8 tons per year. As stated
above, these calculations are based on the emissions rates from burning
coal, not natural gas.
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\270\ Id.
\271\ Idaho 2022 plan submission, pages 69-70.
\272\ Idaho 2022 plan submission, Appendix A. Fire Regime at
Idaho's Class I Areas.
\273\ Ibid.
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Based on the 2022 submission, the conversion to natural gas reduces
NO<INF>X</INF> emissions from the Foster Wheeler Boiler by 243.29 tons
per year--from 302.59 tons per year (2014 baseline emissions) to
projected emissions of 59.3 tons per year and more than 152.49 tons per
year emissions reduction than with SNCR.\274\ Given these emissions
reductions, Idaho did not reevaluate the feasibility or cost of
NO<INF>X</INF> controls on the Foster Wheeler Boiler assuming the unit
only fires natural gas.\275\
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\274\ Idaho 2022 plan submission, page 72, table 35.
\275\ Ibid.
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For SO<INF>2</INF>, Idaho evaluated the cost, time necessary to
install, energy and non-air quality impact and remaining useful life of
WFGD, dry FGD, and DSI.\276\ Idaho determined the cost-effectiveness of
each of the controls as: $4,720 per ton for wet FGD, $4,810 per dry
FGD, and $5,420 per ton for dry sorbent injection. Idaho noted that if
a higher bank prime interest rate is used and a 20-year equipment life,
then the cost-effectiveness of WFGD and dry FGD exceed $6,100 per
ton.\277\ Idaho indicated in its 2022 submission that dry sorbent
injection was the only cost-effective control.\278\ Idaho determined
that it would take 36 months to install each of these controls. Idaho
also noted that the energy and non-air quality impacts are similar to
those for the B&W Boiler. Finally, Idaho determined that the equipment
would have a remaining useful life of 20 years.\279\ Installation of
dry FGD as a best control option would result in a 250.2 tons per year
annual SO<INF>2</INF> emissions reduction. However, as stated above,
these calculations were based on the emissions rates from burning coal,
not natural gas. Based on the 2022 submission, the conversion to
natural gas reduces SO<INF>2</INF> emissions from the Foster Wheeler
Boiler by over 499.91 tons per year--from 500.41 tons per year (2014
Baseline emissions) to a projected 0.5 tons per year, reducing annual
emissions by 249.71 tons more than dry FGD.\280\
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\276\ Idaho 2022 plan submission, Appendix B. Regional Haze
Four-Factor Analysis Reviews, The Amalgamated Sugar Company--Twin
Falls.
\277\ Ibid.
\278\ Idaho 2022 plan submission, pages 69-70.
\279\ Ibid.
\280\ Idaho 2022 plan submission, page 72, table 35.
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Idaho determined that no additiona
[…truncated; see source link]Indexed from Federal Register on March 24, 2025.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.