[Federal Register Volume 90, Number 208 (Thursday, October 30, 2025)]
[Proposed Rules]
[Pages 48855-48880]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-19713]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R10-OAR-2023-0348; FRL-11133-01-R10]
Air Plan Approval; AK; 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 Alaska regional haze plan for the second implementation
period. Alaska submitted the plan to address applicable requirements
under the Clean Air Act and the EPA's Regional Haze Rule.
DATES: Written comments must be received on or before December 1, 2025.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R10-
OAR-2023-0348 at https://www.regulations.gov. For comments submitted at
regulations.gov, follow the online instructions for submitting
comments. Once submitted, comments may not be edited or removed from
regulations.gov. 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.
[[Page 48856]]
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 https://www.epa.gov/dockets/commenting-epa-dockets.
FOR FURTHER INFORMATION CONTACT: Kristin Hall, EPA Region 10, 1200
Sixth Avenue, Suite 155, Seattle, WA 98101, at (206) 553-6357 or
[email protected].
SUPPLEMENTARY INFORMATION: Throughout this document, the use of ``we''
and ``our'' means ``the EPA.''
Table of Contents
I. What action is the EPA proposing?
II. Background and Requirements for Regional Haze Plans
A. Regional Haze
B. The Western Regional Air Partnership
III. 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
IV. The EPA's Evaluation of the Alaska Regional Haze Plan for the
Second Implementation Period
A. Background on the Alaska First Implementation Period Plan
B. The Alaska Second Implementation Period Plan 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
V. Proposed Action
VI. Incorporation by Reference
VII. Statutory and Executive Order Reviews
I. What action is the EPA proposing?
The EPA is proposing to approve the Alaska regional haze plan for
the second implementation period as meeting the Regional Haze Rule
(RHR) requirements of 40 CFR 51.308(f)(1) through (6), (g)(1) through
(5), and (i). The Alaska Department of Environmental Conservation (DEC)
submitted the regional haze plan on July 25, 2022, as a State
Implementation Plan (SIP) revision, and clarified aspects of the
submission on October 6, 2025. In addition, as requested by the Alaska
DEC in the submission, we are proposing to approve and incorporate by
reference into the Alaska SIP at 40 CFR 52.70(c), two new regulatory
provisions of Alaska Administrative Code Title 18 Environmental
Conservation, Chapter 50 Air Quality Control (18 AAC 50), specifically,
18 AAC 50.025 and 18 AAC 50.265, State effective August 21, 2022. The
EPA is proposing this action pursuant to Clean Air Act (CAA) sections
110 and 169A.
II. Background and Requirements for Regional Haze Plans
A detailed history and background of the regional haze program is
provided in multiple prior EPA proposal actions.\1\ For additional
background on the 2017 RHR revisions, please refer to section III of
this document. Overview of Visibility Protection Statutory Authority,
Regulation, and Implementation of ``Protection of Visibility:
Amendments to Requirements for State Plans'' of the 2017 RHR.\2\ The
following is an abbreviated history and background of the regional haze
program and 2017 RHR as it applies to the current action.
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\1\ See 90 FR 13516 (March 24, 2025).
\2\ See 82 FR 3078 (January 10, 2017) at page 3081.
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A. Regional Haze
In the 1977 CAA Amendments, Congress created a program for
protecting visibility in the nation's mandatory Class I Federal areas,
which include certain national parks and wilderness areas. See CAA
section 169A. The CAA establishes 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.'' See CAA section 169A(a)(1).
In CAA section 169A(a)(1), Congress established the national goal
of preventing any future and remedying any existing impairment of
visibility in mandatory Class I Federal areas that results from manmade
(anthropogenic) air pollution. The core component of a regional haze
SIP submission for the second implementation period is a strategy that
addresses regional haze in each Class I area within the State's borders
and each Class I area outside the State that may be affected by
emissions originating from within the State, CAA section 169A(b)(2)(B),
40 CFR 51.308(f)(2), and makes ``reasonable progress'' toward the
national goal based on consideration of the four statutory factors in
CAA section 169A(g)(1)--the costs of compliance, the time necessary for
compliance, the energy and non-air quality environmental impacts of
compliance, and the remaining useful life of any potentially affected
sources.\3\
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\3\ CAA section 169A(g)(1); 40 CFR 51.308(f)(2)(i).
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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 (SO2), nitrogen oxides (NOX), and, in
some cases, volatile organic compounds (VOC) and ammonia
(NH3)). Fine particle precursors react in the atmosphere to
form fine particulate matter (PM2.5), which impairs
visibility by scattering and absorbing light. Visibility impairment
reduces the perception of clarity and color, as well as visible
distance.\4\
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\4\ 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 RHR. 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 for
expressing visibility and is measured in inverse megameters
(Mm-1). The formula for the deciview is 10 ln (b\ext\)/10
Mm-1). See 40 CFR 51.301.
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To address regional haze visibility impairment, the 1999 RHR
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 contribute to any impairment
of visibility'' in a Class I area to periodically submit SIP revisions
to address such impairment. See CAA 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.
[[Page 48857]]
On January 10, 2017, the EPA promulgated revisions to the RHR that
apply for the second and subsequent implementation periods (82 FR 3078,
January 10, 2017). The reasonable progress requirements as revised in
the 2017 RHR revisions are codified at 40 CFR 51.308(f).
B. The Western Regional Air Partnership
The Western Regional Air Partnership (WRAP) \5\ is one of five
regional air quality planning organizations across the United
States.\6\ The WRAP functions as a voluntary partnership of State,
Tribe, Federal, and Local air agencies whose purpose is to understand
current and evolving air quality issues in the West. There are 15
member States, including Alaska, 28 Tribes, and 30 Local air agency
members.\7\ Federal partners include the EPA, the National Park
Service, the U.S. Fish and Wildlife Service, the Forest Service, and
the Bureau of Land Management.
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\5\ The WRAP website may be found at https://westar.org/.
\6\ See https://www.epa.gov/visibility/visibility-regional-planning-organizations/ for information about the regional planning
organizations, or RPOs, for visibility.
\7\ The WRAP membership list may be found at https://www.westar.org/wrap-council-members/.
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Based on emissions and monitoring data supplied by its membership,
the WRAP produced technical tools to support modeling of visibility
impacts at Class I areas across the West.\8\ The WRAP Technical Support
System for the second implementation period or ``TSSV2'' consolidated
air quality monitoring data, meteorological and receptor modeling data
analyses, emissions inventories and projections, and gridded air
quality/visibility regional modeling results. The TSSV2 is accessible
by members and allows for the creation of maps, figures, and tables to
export and use in developing regional haze plans and maintains the
original source data for verification and further analysis.\9\
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\8\ Technical information may be found at https://www.westar.org/wrap-technical-steering- committee/.
\9\ The WRAP TSSV2 for the second implementation period may be
found at https://views.cira.colostate.edu/tssv2/.
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III. Requirements for Regional Haze Plans for the Second Implementation
Period
Under the CAA and the EPA's regulations, all 50 States, the
District of Columbia, and the U.S. Virgin Islands were required, by
July 31, 2021, to submit regional haze SIP revisions satisfying the
applicable requirements for the second implementation period of the
regional haze program. 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
visibility impairment in Class I areas. CAA section 169A(b)(2)(B). 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 40 CFR 51.308(f)(1) through (3) generally
mirroring the order of the steps in the reasonable progress analysis
\10\ and in 40 CFR 51.308(f)(4) through (6) containing additional,
related requirements.
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\10\ The EPA explained in the 2017 RHR that we were adopting new
regulatory language in 40 CFR 51.308(f) that, unlike the structure
in 40 CFR 51.308(d), ``tracked the actual planning sequence.'' See
82 FR 3078, January 10, 2017, at page 3091.
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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. See 40 CFR 51.308(f), (f)(2). 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. See 40 CFR 51.308(f)(1). 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 CAA section 169A(g)(1) to sources of visibility impairing
pollutants that the State has selected to assess for controls for the
second implementation period. Additionally, as further explained below,
the RHR at 40 CFR 51.3108(f)(2)(iv) separately provides five
``additional factors'' \11\ that States must consider in developing
their long-term strategies. See 40 CFR 51.308(f)(2).
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\11\ The five ``additional factors'' for consideration in 40 CFR
51.308(f)(2)(iv) are distinct from the four factors listed in CAA
section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that States must
consider and apply to sources in determining reasonable progress.
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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 reasonable progress goals (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 CAA. 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
URP 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. 40 CFR 51.308(f)(2) and (3).
There are additional requirements in the rule, including (Federal Land
Manager) FLM consultation, that apply to all visibility protection SIPs
and SIP revisions. See e.g., 40 CFR 51.308(i).
In addition to satisfying the requirements at 40 CFR 51.308(f)
related to reasonable progress, the regional haze plan SIP revisions
for the second implementation period must address the requirements in
40 CFR 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 FLM consultation that apply to all visibility
protection SIPs and SIP revisions. See e.g., 40 CFR 51.308(i).
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 CAA and the EPA's regulations. See CAA section
169A(b)(2); CAA section 110(a). Upon approval by the EPA, a SIP is
enforceable by the Agency and the public under the CAA. If the EPA
finds that a State fails to make a required SIP revision, or if the EPA
finds that a State's SIP is incomplete or if it disapproves the SIP,
the Agency must promulgate a Federal implementation plan (FIP) that
satisfies the applicable requirements. CAA section 110(c)(1).
[[Page 48858]]
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
RHR, 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.'' See 64 FR
35714, July 1, 1999, at pages 35720-22.
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 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 RHR contains requirements in 40 CFR
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 provides
recommendations to assist States in satisfying their obligations under
40 CFR 51.308(f)(1); specifically, in developing information on
baseline, current, and natural visibility conditions, and in making
optional adjustments to the URP to account for the impacts of
international anthropogenic emissions and prescribed fires. See 82 FR
3078, January 10, 2017, at pages 3103-05.
The RHR 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 RHR 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 the 20% most impaired days (the 20% of monitored
days in a calendar year with the highest amounts of anthropogenic
visibility impairment). 40 CFR 51.301. A State must calculate
visibility conditions for both the 20% clearest and the 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). 40 CFR 51.308(f)(1)(i)
and (iii). States must also calculate natural visibility conditions for
the clearest and most impaired days, by estimating the conditions that
would exist on those two sets of days absent anthropogenic visibility
impairment. 40 CFR 51.308(f)(1)(ii). 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 to reach natural visibility conditions.
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
URP--the amount of visibility improvement, measured in deciviews, that
would need to be achieved during each implementation period to achieve
natural visibility conditions by the end of 2064. The URP 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 RHR, the EPA provided States the option of proposing to
adjust the endpoint of the URP to account for impacts of anthropogenic
sources outside the United States and/or impacts of certain types of
wildland prescribed fires. These adjustments 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. See 82 FR 3078, January 10, 2017, at page 3107,
footnote 116.
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 URP. 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 outside the State 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).'' 40 CFR 51.308(f)(2).
The amount of progress that is ``reasonable progress'' is based on
applying the four statutory factors in CAA 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 to make reasonable progress towards the national visibility
goal. See 40 CFR 51.308(f)(2)(i). 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. 40 CFR 51.308(f)(2).
The regulation at 40 CFR 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, the RHR requires States to 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. 40 CFR 51.308(f)(2)(i). A threshold question at this
step is which visibility impairing pollutants will be analyzed.
While States have discretion to choose any source selection
[[Page 48859]]
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 submission 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.\12\ This is accomplished by considering the four factors--``the
costs of compliance, the time necessary for compliance, and the energy
and non-air quality environmental impacts of compliance, and the
remaining useful life of any existing source subject to such
requirements.'' CAA section 169A(g)(1). 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 to satisfy
the CAA's reasonable progress mandate.'' 82 FR 3078, January 10, 2017,
at page 3091. Thus, for each source it has selected for four-factor
analysis,\13\ a State must consider a ``meaningful set'' of technically
feasible control options for reducing emissions of visibility impairing
pollutants. 82 FR 3078, January 10, 2017, at page 3088.
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\12\ The CAA provides that, ``[i]n determining reasonable
progress there shall be taken into consideration'' the four
statutory factors. See CAA 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.
\13\ ``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 RHR 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.'' See 82
FR 3078, January 10, 2017, at page 3088.
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The EPA has also explained that, in addition to the four statutory
factors, States have flexibility under the CAA and RHR to reasonably
consider visibility benefits as an additional factor alongside the four
statutory factors. Ultimately, while States have discretion to
reasonably weigh the factors and to determine what level of control is
needed, 40 CFR 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.''
As explained above, 40 CFR 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 40 CFR 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. If the outcome
of a four-factor analysis is that an emissions reduction measure is
necessary to make reasonable progress towards remedying existing or
preventing future anthropogenic visibility impairment, that measure
must be included in the SIP.
The characterization of information on each of the factors is also
subject to the documentation requirement in 40 CFR 51.308(f)(2)(iii).
The reasonable progress analysis is a technically complex exercise, and
also a flexible one, that provides States with bounded discretion to
design and implement approaches appropriate to their circumstances.
Given this flexibility, 40 CFR 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. Additionally, the RHR at 40 CFR 51.308(f)(2)(iv)
separately provides five ``additional factors'' \14\ 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.
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\14\ The five ``additional factors'' for consideration in 40 CFR
51.308(f)(2)(iv) are distinct from the four factors listed in CAA
section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that States must
consider and apply to sources in determining reasonable progress.
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Because the air pollution that causes regional haze crosses State
boundaries, 40 CFR 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. 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. 40 CFR
51.308(f)(2)(ii)(A). Additionally, the RHR 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. 40 CFR 51.308(f)(2)(ii)(B). 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. 40 CFR 51.308(f)(2)(ii)(C). Under all
circumstances, a State must document in its SIP revision all
substantive consultations with other contributing States. 40 CFR
51.308(f)(2)(ii)(C).
In this proposed action, the EPA notes that it is the Agency's
policy, as announced in the EPA's recent approval of the West Virginia
Regional Haze SIP,\15\ that where the State has considered the four
statutory factors, and visibility conditions for a Class I area
impacted by a State are projected to be below the URP in 2028, the
State has presumptively demonstrated reasonable progress for the second
implementation period for that area. The EPA acknowledges that this
reflects a change in policy as to how the URP should be used in the
evaluation of regional haze second planning period
[[Page 48860]]
SIPs. However, the EPA finds that this policy aligns with the purpose
of the statute and RHR, which is achieving ``reasonable'' progress, not
maximal progress, toward Congress' natural visibility goal.
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\15\ See proposed rulemaking (90 FR 16478, April 18, 2025, at
page 16483) and final rule (90 FR 29737, July 7, 2025, at pages
29738-39).
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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.'' 82 FR 3078, January 10, 2017, at page 3091. 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, 40 CFR 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.''
RPGs may also serve as a metric for assessing the amount of
progress a State is making towards the national visibility goal. To
support this approach, the RHR requires States with Class I areas to
compare the 2028 RPG for the most impaired days to the corresponding
point on the URP 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 URP (i.e., if
visibility conditions are improving more slowly than the rate described
by the URP), 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. 40 CFR 51.308(f)(3)(ii). 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 URP
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.''
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 section 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. 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. 40 CFR 51.308(f)(6), (f)(6)(i), and (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, as well as a Statewide inventory documenting
such emissions. 40 CFR 51.308(f)(6)(ii), (iii), and (v). 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. 40 CFR 51.308(f)(6)(vi).
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 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. See 81 FR 26942, May 4, 2016, at page 26950; see also 82
FR 3078, January 10, 2017, at page 3119. To this end, every State's SIP
revision for the second implementation period is required to assess
changes in visibility conditions and describe the status of
implementation of all measures included in the State's long-term
strategy, including Best Available Retrofit Technology (BART) and
reasonable progress emission reduction measures from the first
implementation period, and the resulting emissions reductions. 40 CFR
51.308(g)(1) and (2).
G. Requirements for State and Federal Land Manager Coordination
CAA 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 FLM or FLMs; pursuant to that consultation, the State
must include a summary of the FLMs' conclusions and recommendations in
the notice to the public. Consistent with this statutory requirement,
the RHR also requires that States ``provide the [FLM] 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 [FLM] can meaningfully inform the State's decisions on the long-
term strategy.'' 40 CFR 51.308(i)(2). For the EPA to evaluate whether
FLM consultation meeting the requirements of the RHR has occurred, the
SIP submission 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 FLMs. 40
CFR 51.308(i)(3). Finally, a SIP revision must provide procedures for
continuing consultation between the State and FLMs 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. 40 CFR 51.308(i)(4).
IV. The EPA's Evaluation of the Alaska Regional Haze Plan for the
Second Implementation Period
A. Background on the Alaska First Implementation Period Plan
On April 4, 2011, Alaska submitted its regional haze plan for the
first implementation period (2008 through 2018). The CAA required that
first implementation period plans include, among other things, a long-
term strategy for making reasonable progress and BART requirements for
certain older facilities, where applicable.\16\ The EPA approved
Alaska's first implementation period plan on February 14, 2013 (78 FR
10546). On March 10, 2016, the State
[[Page 48861]]
submitted a five-year progress report, that the EPA approved on April
12, 2018 (83 FR 15746).\17\
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\16\ The requirements for regional haze SIPs for the first
implementation period are contained in CAA section 169A(b)(2)(B) and
40 CFR 51.308(d) and (e). See also 40 CFR 51.308(b).
\17\ 83 FR 7002, February 16, 2018.
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B. The Alaska Second Implementation Period Plan and the EPA's
Evaluation
On July 25, 2022, Alaska submitted its regional haze plan for the
second implementation period.\18\ The Alaska DEC made the plan
available for public comment from March 30, 2022, through May 24, 2022,
and held a public hearing on May 10, 2022.\19\ Alaska received and
responded to public comments and included the comments and responses in
the regional haze plan submission.\20\ We note that, to address certain
regional haze requirements, the 2022 regional haze plan submission
relied in part on SO2 best available control technology
(BACT) analyses originally conducted and submitted as part of the
Fairbanks PM2.5 serious nonattainment plan in 2020 and
2021.\21\ However, Alaska subsequently revised the original
SO2 BACT analyses to address EPA concerns and to account for
more recent vendor quotes and fuel prices.\22\ These updated
SO2 BACT analyses were later submitted by Alaska to the EPA
as part of a December 4, 2024, SIP revision to the Fairbanks
PM2.5 serious area nonattainment plan.\23\
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\18\ CAA sections 169A; 40 CFR 51.308(f).
\19\ Alaska submission, regional haze public notice document
dated March 30, 2022, and regional haze affidavit of oral hearing
document dated July 1, 2022.
\20\ Alaska submission, regional haze response to comments (RTC)
document dated July 5, 2022.
\21\ Determinations of Attainment by the Attainment Date,
Determinations of Failure To Attain by the Attainment Date and
Reclassification for Certain Nonattainment Areas for the 2006 24-
Hour Fine Particulate Matter National Ambient Air Quality Standards,
published May 10, 2017 (82 FR 21711).
\22\ The EPA's concerns were detailed in the Agency's proposed
disapproval of the plan on January 10, 2023, at 88 FR 1454.
\23\ The 2024 Fairbanks plan submission may be found in docket
EPA-R10-OAR-2024-0595 at https://www.regulations.gov/docket/EPA-R10-OAR-2024-0595/.
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To clarify the relationship between the Alaska regional haze plan
and the revisions to the Fairbanks PM2.5 serious area
nonattainment plan, Alaska sent a letter to the EPA on October 6, 2025.
The letter stated that Alaska was relying on the 2024 updated
SO2 BACT analyses to meet the regional haze four-factor
analysis requirements for the second implementation period.
Accordingly, the State found no SO2 controls to be necessary
for reasonable progress in the second implementation period. The
following sections describe in detail the Alaska regional haze plan
submission and clarification letter, including, but not limited to, air
quality modeling conducted, source selection, control measure analysis,
and visibility improvement progress at Class I areas in Alaska. The
following sections also describe the EPA's evaluation of the submission
against the requirements of the CAA and RHR for the second
implementation period. The submission, clarification letter, and other
supporting documents may be found in the docket for this action.
C. Identification of Class I Areas
Section 169A(b)(2) of the CAA 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 RHR 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.
The EPA concluded in the 1999 RHR that ``all [s]tates contain
sources whose emissions are reasonably anticipated to contribute to
regional haze in a Class I area,'' 64 FR 35714, July 1, 1999, at page
35721, and this determination was not changed in the 2017 RHR.
Critically, the statute and regulation both require that the cause-or-
contribute assessment consider all emissions of visibility impairing
pollutants from a State, as opposed to emissions of a particular
pollutant or emissions from a certain set of sources.
1. Alaska Class I Areas
Alaska has four Class I areas: \24\ Denali National Park and
Preserve (Denali National Park), Tuxedni National Wildlife Refuge/
National Wilderness Area (Tuxedni Wilderness Area), Simeonof National
Wildlife Refuge/National Wilderness Area (Simeonof Wilderness Area),
and the Bering Sea National Wildlife Refuge/National Wilderness Area
(Bering Sea Wilderness Area). These areas are described in the
following paragraphs.
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\24\ Section 169A of the CAA was established in 1977 to protect
visibility in all wilderness areas over 5,000 acres and all national
parks over 6,000 acres. 156 such areas were designated throughout
the U.S.
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a. Denali National Park
Denali National Park comprises more than six million acres in the
Alaska interior managed by the National Park Service. Mountains are a
prominent feature of the park, reaching 20,320 feet elevation.\25\ The
surrounding tundra and taiga are home to dozens of mammals, including
Dall sheep, caribou, grizzly bears, moose, foxes, lynx, and marmots, to
name a few. Over 400 flowering plants grow there, and over 100 bird
species have been sighted.\26\
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\25\ See National Park Service web page for Denali National Park
and Preserve at https://www.nps.gov/dena/index.htm/.
\26\ See Wilderness Connect website at https://wilderness.net/visit-wilderness/?ID=153/.
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b. Simeonof Wilderness Area
The Simeonof Wilderness Area is managed by the U.S. Fish and
Wildlife Service.\27\ It covers 25,855 acres, including the water,
shoals, and kelp beds within one mile of Simeonof Island.\28\ The
wilderness area is home to over 55 species of birds as well as sea
otters, hair seals, walruses, and whales.\29\ Sandpoint, population
652, is the nearest community, located on an island approximately 60
miles northwest of the wilderness area.\30\
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\27\ See Alaska Maritime National Wildlife Refuge Wilderness
Areas web page, which includes Simeonof Wilderness, on the U.S. Fish
and Wildlife Service website at https://www.fws.gov/node/267174/.
\28\ See Wilderness Connect website at https://wilderness.net/visit-wilderness/?ID=555/.
\29\ Alaska submission, Combined Section III.K.13, Page A-8.
\30\ U.S. census data, available in the docket for this action
and https://live.laborstats.alaska.gov/pop/index.cfm/.
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c. Tuxedni Wilderness Area
The Tuxedni Wilderness Area was established on Chisik and Duck
islands at the mouth of Tuxedni Bay.\31\ The 5,566-acre wilderness area
is managed by the U.S. Fish and Wildlife Service. The remote area is a
refuge for seabirds, bald eagles and peregrine falcons. Access is
limited to small boats and planes, when the weather allows.\32\
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\31\ See Alaska Maritime National Wildlife Refuge Wilderness
Areas web page, which includes Tuxedni Wilderness, on the U.S. Fish
and Wildlife Service website at https://www.fws.gov/node/267174/.
\32\ Wilderness Connect website at https://wilderness.net/visit-wilderness/?ID=614/.
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d. Bering Sea Wilderness Area
The Bering Sea Wilderness Area is the most isolated and remote
Class I area in the U.S.\33\ It is located on a collection
[[Page 48862]]
of islands in the Bering Sea, 350 miles southwest of Nome, Alaska. The
U.S. Fish and Wildlife Service manages the 81,340 acres, where millions
of seabirds congregate, as well as northern sea lions, seals, and
walruses.\34\
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\33\ See Alaska Maritime National Wildlife Refuge Wilderness
Areas web page, which includes Bering Sea Wilderness, on the U.S.
Fish and Wildlife Service website https://www.fws.gov/node/267174/.
\34\ See Wilderness Connect website at https://wilderness.net/visit-wilderness/?ID=36/.
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2. Alaska Visibility Monitors
Haze species at Alaska Class I areas are measured and analyzed via
the IMPROVE network.\35\ Table 1 of this document lists the IMPROVE
monitors representing visibility at Alaska Class I areas.
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\35\ See IMPROVE website at https://vista.cira.colostate.edu/Improve/.
Table 1--Monitors Representing Visibility at Alaska Class I Areas \36\
----------------------------------------------------------------------------------------------------------------
Monitor ID Sponsor Class I area Years operated
----------------------------------------------------------------------------------------------------------------
DENA1............................. National Park Service..... Denali National Park...... 1988-present.
SIME1............................. U.S. Fish and Wildlife Simeonof Wilderness Area.. 2001-present.
Service.
TUXE1............................. U.S. Fish and Wildlife Tuxedni Wilderness Area... 2001-2014.
Service.
KPBO1............................. U.S. Fish and Wildlife Tuxedni Wilderness Area... 2016-present.
Service.
----------------------------------------------------------------------------------------------------------------
We note that, due to its extremely remote location and lack of
reliable power, there is no visibility monitoring at the Bering Sea
Wilderness Area.\37\ No electricity or other infrastructure exists to
support a monitoring effort on the uninhabited islands that make up
this wilderness area. A DELTA-DRUM mobile sampler was installed during
a field visit in 2002, but due to power supply issues, no viable
baseline data were collected.\38\ We acknowledge that the RHR
contemplates that for areas without onsite monitoring, States should
work with the EPA to use other available, representative monitoring
data to establish a baseline.\39\ However, because this wilderness area
is in the middle of the Bering Sea, hundreds of miles from the mainland
and any other monitoring locations, data from other sites in Alaska are
not considered representative of visibility at the Bering Sea
Wilderness Area.
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\36\ Sources: Alaska submission, Combined Section III.K.13, Page
III.K.13.C1 through C-4 and FLM Environmental Database, available
online at https://views.cira.colostate.edu/fed/ using Query Wizard,
Sites Tab.
\37\ See IMPROVE website at https://vista.cira.colostate.edu/Improve/improve-program/.
\38\ See our proposed action on the first implementation period
SIP submission on February 24, 2012, 77 FR 11022, at pages 11028-29.
\39\ 40 CFR 51.308(d)(2)(i).
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In the regional haze plan for the first implementation period,
Alaska evaluated and discussed the potential for future anthropogenic
emissions to impact visibility at the Bering Sea Wilderness Area, and
concluded that future impacts from any local industrial, commercial, or
community developments were highly unlikely.\40\ The State acknowledged
that visibility in the area would continue to be influenced by
international sources beyond Alaska's control, and may also be
influenced by future emissions from international commercial shipping
and oil and gas development in the Bering Sea. However, these latter
source categories are under Federal jurisdiction. With respect to
global shipping, the International Marine Organization (IMO) global
sulfur limit rule went into effect on January 1, 2020.\41\ This rule
applies to all commercial shipping and limits fuel sulfur content to
0.5%.\42\ This is a seven-fold decrease in fuel sulfur content from the
prior IMO limit of 35,000 part per million. While the EPA cannot
estimate the exact impact of the sulfur limits on visibility impairment
at Bering Sea, this new rule is likely to reduce sulfate formation in
the area.\43\ Based on this information, the EPA approved Alaska's
approach to the Bering Sea Wilderness Area in the first implementation
period.
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\40\ See Alaska Regional Haze Plan submission for the first
implementation period, February 11, 2011, at https://www.regulations.gov docket EPA-R10-OAR-2011-0367, document EPA-R10-
OAR-2011-0367-0002 at pages III.K.4-120 through 121.
\41\ Fuel sulfur limits are codified at 40 CFR part 1043. See 84
FR 69335, 69336 (December 18, 2019).
\42\ Id.
\43\ See 88 FR 33555, 33557 (May 24, 2023).
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For the second implementation period, Alaska stated in its regional
haze plan submission that, due to the logistical challenges associated
with monitoring this remote location, there have been no monitoring
attempts since 2002, and none are currently planned.\44\ Consistent
with our action on Alaska's first implementation period regional haze
plan, we have determined that Alaska's approach to the Bering Sea
Wilderness Area in the second implementation period is reasonable.
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\44\ Alaska submission, Combined Section III.K.13, Page
III.K.13.C-4.
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In addition, we note that Alaska operates an IMPROVE protocol site
south of Denali National Park at Trapper Creek (TRCR1), which is sited
to evaluate potential transport of pollution into the park from
Anchorage and areas to the south.\45\ While data from this protocol
site may be compared to data from the DENA1 site, the DENA1 site
remains the official IMPROVE site representative of visibility
conditions in Denali National Park.\46\
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\45\ Id., Page III.K.13.C-1 and Figures III.K.D-2, D-6, D-10, D-
14.
\46\ See IMPROVE website at https://vista.cira.colostate.edu/Improve/.
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As detailed in the submission, Alaska determined there are no Class
I areas in other States affected by emissions from Alaska sources.\47\
Alaska borders no other State and is geographically distant from all
other States.\48\ We concur with the State's finding that emissions
from Alaska sources do not impact Class I areas outside the State.\49\
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\47\ Alaska submission, Combined Section III.K.13, Page
III.K.13.C-1.
\48\ Id., Page III.K.13.A-7.
\49\ 78 FR 10546, February 14, 2013.
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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 URP. This section also provides the
option for States to propose adjustments to the URP line for a Class I
area to account for visibility impacts from anthropogenic sources
outside the United States and/or the impacts from wildland prescribed
fires that were conducted for certain, specified objectives. 40 CFR
51.308(f)(1)(vi)(B).
[[Page 48863]]
1. Alaska Visibility Conditions
The Alaska regional haze plan submission addressed baseline,
current, and natural visibility conditions, and the URP for each Class
I area--with the exception of Bering Sea Wilderness Area--as required
by the RHR and the EPA's technical guidance on tracking visibility
progress.\50\ Tables 2 and 3 of this document summarize visibility data
provided in the Alaska submission, including adjustments by the EPA to
the natural conditions endpoint and URP to account for certain
international sources of anthropogenic sulfate.\51\ We note that, to
attempt to further quantify out-of-State and natural sources of
sulfate, Alaska worked with the University of Alaska Fairbanks to run
GEOS-Chem, a global 3-dimensional chemical transport model, and
included the modeling results in the submission, as further discussed
in section IV.F. of this document.\52\
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\50\ EPA Technical Guidance on Tracking Visibility Progress for
the Second Implementation Period of the Regional Haze Program,
December 2018.
\51\ Specifically, the EPA adjusted natural conditions on the
20% most impaired days from 4.7 to 5.6 deciviews for DENA1, 8.5 to
12.9 deciviews for SIME1, and 7.0 to 9.9 deciviews for TUXE1. See
Technical Support Document for the EPA's Updated 2028 Regional Haze
Modeling for Hawaii, Virgin Islands, and Alaska. EPA-454/R-21-007.
August 2021.
\52\ Alaska submission, Appendix III.K.13.G. Modeling.
\53\ Sources: Alaska submission, Combined Section III.K.13,
Tables III.K.D-3 through D-8 and Tables III.K.13.I-1 and I-2; and
Technical Support Document for the EPA's Updated 2028 Regional Haze
Modeling for Hawaii, Virgin Islands, and Alaska, EPA-454/R-21-007,
August 2021. Note: A full dataset was not yet available for KPBO1 at
the time Alaska developed the submission and the EPA conducted its
modeling.
Table 2--Clearest Days Visibility Conditions at Alaska Class I Areas in Deciviews \53\
----------------------------------------------------------------------------------------------------------------
Baseline 2000- Current 2014-
Monitor ID Class I area 2004 2018
----------------------------------------------------------------------------------------------------------------
DENA1......................................... Denali National Park............ 2.4 2.2
SIME1......................................... Simeonof Wilderness............. 7.6 7.7
TUXE1......................................... Tuxedni Wilderness.............. 4.0 3.9
----------------------------------------------------------------------------------------------------------------
Table 3--Most Impaired Days Visibility Conditions at Alaska Class I Areas in Deciviews \54\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline 2000- Current 2014- EPA-adjusted EPA-adjusted
Monitor ID Class I area 2004 2018 URP 2028 natural 2064
--------------------------------------------------------------------------------------------------------------------------------------------------------
DENA1........................................... Denali National Park.............. 7.1 6.6 6.5 5.6
SIME1........................................... Simeonof Wilderness............... 13.7 13.9 13.4 12.9
TUXE1........................................... Tuxedni Wilderness................ 10.5 10.0 10.3 9.9
--------------------------------------------------------------------------------------------------------------------------------------------------------
a. Denali National Park
The data in Tables 2 and 3 of this document suggest that current
visibility at DENA1 has improved since the baseline period for both the
clearest and most impaired days.\55\ In addition, current conditions at
DENA1 appear to be within half of a deciview of the EPA-adjusted URP
for 2028 and within one deciview of the EPA-adjusted natural conditions
for both the clearest and most impaired days.\56\
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\54\ Sources: Alaska submission, Combined Section III.K.13,
Tables III.K.D-3 through D-8 and Tables III.K.13.I-1 and I-2; and
Technical Support Document for the EPA's Updated 2028 Regional Haze
Modeling for Hawaii, Virgin Islands, and Alaska, EPA-454/R-21-007,
August 2021. Note: a full dataset was not yet available for KPBO1 at
the time Alaska developed the submission and the EPA conducted its
modeling.
\55\ Technical Support Document for the EPA's Updated 2028
Regional Haze Modeling for Hawaii, Virgin Islands, and Alaska. EPA-
454/R-21-007. August 2021.
\56\ The data also show that at the TRCR1 protocol site,
visibility on the clearest days was 3.5 deciviews at baseline and
3.4 deciviews at current conditions, and visibility on the most
impaired days was 9.1 deciviews at baseline, and 8.8 deciviews at
current conditions. Alaska submission, Combined Section III.K.13,
Tables III.K.D.4 and III.K.D.8.
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Alaska provided data in the submission showing that ammonium
sulfate and organic mass are the dominant haze species at DENA1.\57\
Anthropogenic and natural sources of sulfate from inside and outside
Alaska are thought to contribute to sulfate at DENA1.\58\ The
submission highlighted a number of anthropogenic sources of pollution
located near DENA1, including Denali National Park Headquarters, Park
Road, Alaska Railroad, Usibelli Coal Mine, and the Healy Power
Plant.\59\ We further discuss sulfur dioxide emissions from the Healy
Power Plant in section IV.E. of this document.
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\57\ Alaska submission, Combined Section III.K.13, Figures
III.K.D-2 and D-3.
\58\ Id., Pages III.K.13.D-8 through D-12.
\59\ Id., Page III.K.13.D-8.
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Alaska stated in the submission that the organic mass contribution
at DENA1 may primarily be explained by wildfires in south central
Alaska.\60\ The EPA fire emissions inventory and the Alaska fire
emissions inventory show variability from year to year.\61\ Alaska also
noted that 2009 was a significant fire wildfire year when 2.9 million
acres burned in interior Alaska.\62\ The Redoubt volcano in
southcentral Alaska, a source of SO2 emissions and potential
sulfate contributions, erupted that same year.\63\
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\60\ Id., Pages III.K.E-11 through E-15.
\61\ Id., Table III.K.13.E-5 Data from SmartFire2/BlueSky
framework and Table III.K.13.E-6 Data from the Alaska Interagency
Coordination Center (AICC).
\62\ Id., Page III.K.13.D-13.
\63\ See also The 2009 Eruption of Redoubt Volcano, Alaska,
State of Alaska, Department of Natural Resources, 2012. Available at
https://pubs.usgs.gov/publication/70007150/.
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b. Simeonof Wilderness Area
At first glance, the data in Tables 2 and 3 of this document
suggest that current visibility at SIME1 may have degraded since the
baseline period for both the clearest and most impaired days. However,
the EPA reviewed the underlying data used to calculate the average haze
indices for SIME1 and found no statistical difference between baseline
and current conditions for the clearest and most impaired days at
SIME1. The EPA's technical memo documenting the statistical analysis
may be found in the docket for this action.\64\ In addition, current
conditions at SIME1 appear to be within half a deciview of the EPA-
adjusted URP for 2028, and within two deciviews of the EPA-
[[Page 48864]]
adjusted natural conditions for both the clearest and most impaired
days.
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\64\ Statistical analysis comparing the current 2014-2018
visibility conditions to baseline 2000-2004 conditions for the 20%
most impaired days and 20% clearest days at the Alaska Simeonof
Wilderness (SIME1) IMPROVE monitoring site, U.S. Environmental
Protection Agency, Region 10, Laboratory Services and Applied
Science Division; Kotchenruther, R. (June 27, 2023).
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In the submission, Alaska stated that visibility impairment at
SIME1 is primarily due to ammonium sulfate followed by sea salt.\65\
Alaska further stated that anthropogenic sources of sulfate are likely
to include commercial marine vessel emissions from ships transiting the
international shipping lane near the monitor, but that natural sources
of sulfate at SIME1 are important. The near-ocean location of SIME1
yields significant sea salt contribution, as reflected in the IMPROVE
data.\66\ Oceanic dimethyl sulfide, a volatile sulfur compound that is
produced by plankton and converted to SO2 in the marine
atmosphere, is also understood to contribute.\67\ Alaska estimated that
roughly 60 percent of oceanic dimethyl sulfide is converted to
SO2 in the Gulf of Alaska, however, the exact contribution
of dimethyl sulfide to sulfate at SIME1 is unknown at this time. \68\
In addition, Alaska stated that SIME1 is likely influenced by sulfur
degassing from nearby active and semi-active volcanoes.\69\
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\65\ Alaska submission, Combined Section III.K.13, Figures
III.K.13.D-10 and D-11.
\66\ Ibid.
\67\ Id., Pages III.K.13.E-16, E-17.
\68\ Id., Page III.K.13.E-16.
\69\ Id., Page III.K.13.D-17.
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c. Tuxedni Wilderness Area
The data in Tables 2 and 3 of this document suggest that current
visibility at TUXE1 has improved since the baseline period for both the
clearest and most impaired days.\70\ In addition, current conditions at
TUXE1 appear to be within half a deciview of the EPA-adjusted URP for
2028 and within one deciview of the EPA-adjusted natural conditions for
both the clearest and most impaired days.
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\70\ The EPA adjusted the natural visibility end point for
Alaska Class I areas to account for certain international
anthropogenic sulfate. See Technical Support Document for the EPA's
Updated 2028 Regional Haze Modeling for Hawaii, Virgin Islands, and
Alaska. EPA-454/R-21-007. August 2021.
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We note that the TUXE1 monitor was re-located in 2015, from the
west side of Cook Inlet to the east side in the Kenai Peninsula Borough
(KPBO1) due to monitor access issues.\71\ The last year of complete
data for TUXE1 was 2014, therefore, Alaska calculated current
conditions for TUXE1 using 2012 through 2014 data. The first full year
of data for KPBO1 was 2016. The Alaska submission stated that the next
regional haze progress report would include a full dataset and analysis
for KPBO1.\72\ We find this approach to data handling reasonable for
the TUXE1 and KPBO1 monitors. Both the TUXE1 and KPBO1 monitors are
IMPROVE monitors that are representative of visibility conditions in
the Tuxedni Wilderness Area.
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\71\ Alaska submission, Section III.K.13 Combined Sections, Page
II.K.13.C-3.
\72\ Id., Page III.K.13.D-7.
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For the clearest days, Alaska found that the annual total light
extinction at KPBO1 was slightly higher than TUXE1 and appeared to be
more evenly distributed among ammonium sulfate, coarse mass, organic
mass, and sea salt.\73\ On the most impaired days, the annual
extinction at TUXE1 was predominantly ammonium sulfate.\74\ Because the
monitor only began yielding data in 2016, a full dataset was not
available to calculate annual extinction at KPBO1 for the most impaired
days. The Alaska submission stated that the next regional haze progress
report would include a full dataset and analysis for KPBO1.\75\
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\73\ Id., Figure III.K.13.D-18.
\74\ Id., Figure III.K.13.D-14.
\75\ Id., Page III.K.13.D-7.
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Alaska estimated that the largest categories of anthropogenic
impairment at TUXE1 and KPBO1 were most likely to include offshore oil
drilling platforms and oil and gas facilities in the Cook Inlet. As
part of the source selection process, the State reviewed actual sulfur
dioxide emissions at a number of platforms and facilities in the Cook
Inlet. Please see section IV.E. of this document for further details.
In conclusion, the EPA proposes to find that the Alaska submission
meets the requirements of 40 CFR 51.308(f)(1) to calculate baseline,
current, and natural visibility conditions; progress to date; and
uniform rate of progress for the second implementation period. For this
reason, we propose to approve the portions of the Alaska regional haze
plan submission relating to 40 CFR 51.308(f)(1).
E. Long-Term Strategy for Regional Haze
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).'' 40 CFR 51.308(f)(2).
The regulation at 40 CFR 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.
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 submission 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.\76\ This is accomplished by considering the four factors--``the
costs of compliance, the time necessary for compliance, and the energy
and non-air quality environmental impacts of compliance, and the
remaining useful life of any existing source subject to such
requirements.'' CAA section 169A(g)(1). The EPA has explained that the
four-factor analysis is an assessment of potential emission reduction
measures (i.e., control options) for sources; Thus, for each source it
has selected for four-factor analysis, a State must consider a
``meaningful set'' of technically feasible control options for reducing
emissions of visibility impairing pollutants.\77\
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\76\ The CAA provides that, ``[i]n determining reasonable
progress there shall be taken into consideration'' the four
statutory factors. CAA 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 planning period.
\77\ ``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 RHR 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.
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The EPA has also explained that, in addition to the four statutory
factors, States have flexibility under the CAA and RHR to reasonably
consider visibility benefits as an additional factor alongside the four
statutory factors.\78\ Ultimately, while States have discretion to
reasonably weigh the factors and to determine what level of control is
needed, 40 CFR 51.308(f)(2)(i) provides
[[Page 48865]]
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.''
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\78\ 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, at page 186.
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As explained above, 40 CFR 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 40 CFR 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. If the outcome
of a four-factor analysis is that an emissions reduction measure is
necessary to make reasonable progress towards remedying existing or
preventing future anthropogenic visibility impairment, that measure
must be included in the SIP.
The following paragraphs describe how the Alaska regional haze plan
submission addresses the requirements of 40 CFR 51.308(f)(2) and
summarize the EPA's evaluation.
1. Alaska Focus on Sulfur Dioxide Emissions
In the regional haze plan for the first implementation period,
Alaska evaluated both NOX and SO2 potential
contributions to haze species at Alaska Class I areas. In the regional
haze plan for the second implementation period, Alaska provided data
that showed ammonium sulfate is the dominant haze species, comprising
approximately 60% of the annual average light extinction composition on
the 20% most impaired days.\79\ When looking at the most
anthropogenically impaired days, Alaska estimated ammonium sulfate
comprised over 95% of the annual extinction composition at Alaska Class
I areas.\80\ Therefore, Alaska focused on SO2 emissions in
the regional haze second implementation period. Based on a review of
the submission and a review of IMPROVE data from the FLM Environmental
Database,\81\ we propose to find that it is reasonable for Alaska to
focus on SO2 emissions in the second implementation
period.\82\
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\79\ Alaska submission, Section III.K.13 Combined Sections,
Figure III.K.13.F-2.
\80\ Id. Figure III.K.13.F-3.
\81\ Annual average extinction composition for the years 2000
through 2021 for DENA1, SIME1, and TUXE1. See ``210 EPA Alaska
Sulfate Nitrate Alaska IMPROVE Stations.xls'' in the docket for this
action. Data pulled from FED AQRV Summary--Light Extinction
Composition--Product #XAQR_BCSB_ANYR. FLM Environmental Database
(FED); CSU and the Cooperative Institute for Research in the
Atmosphere (CIRA), May 23, 2023.
\82\ EPA 2019 Guidance at page 11. See also the EPA's Technical
Guidance on Tracking Visibility Progress for the Second
Implementation Period of the Regional Haze Program, U.S.
Environmental Protection Agency, EPA-454/R-18-010, December 2018.
Page 12, Step 3.a.
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2. Alaska Source Selection
Alaska employed a two-step source selection process, as detailed in
the submission.\83\ In step one, Alaska identified the geographic areas
in which a variety of sources may have the potential to impact
visibility at Alaska Class I areas. The State relied on HYSPLIT
modeling \84\ to estimate back trajectories for each IMPROVE station
for the most impaired days in 2014 to 2018, and used the back
trajectories to perform an Area of Influence (AOI) and Weighted
Emissions Potential (WEP) analysis.\85\ Step one yielded 26 point and
area sources, which Alaska then ranked based on 2014 and 2017
SO2 emissions and WEP sulfate potential.\86\
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\83\ Alaska submission, Combined Section III.K.13, Pages
III.K.13.F-1 through F-12.
\84\ Hybrid Single-Particle Lagrangian Integrated Trajectory
(HYSPLIT) model, developed by the National Oceanic and Atmospheric
Administration Air Resources Lab.
\85\ Alaska submission, Appendix III.K.13.G. Modeling.
\86\ Alaska submission, Combined Section III.K.13, Pages
III.K.13.F-5 through F-12 and Appendix III.K.F-Part-1.
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In step two, Alaska followed a Q/d methodology, which is a
screening method described in the EPA 2019 guidance, where ``Q'' is a
source's actual sulfur dioxide emissions, primarily based on the 2017
National Emissions Inventory, and ``d'' is the distance from the source
to the nearest Class I area.\87\ The sources with SO2 Q/d
values greater than or equal to 1.0 were selected by Alaska for further
analysis.\88\
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\87\ Alaska used 2017 National Emissions Inventory data for
``Q'' because it was considered by the State to be more accurate
than 2014v2 National Emissions Inventory data for the sources being
evaluated. Some sources screened in step one were found to have
significant differences between 2014 and 2017 actual SO2
emissions due to changes in operation, fuel use, and emissions
reporting. See Alaska submission, Appendix III.K.13.F-Part-1 for
more information.
\88\ The Alaska submission stated that this threshold metric is
appropriate, in part because it is more conservative than the
threshold metric used in the initial screening criteria detailed in
the FLM Air Quality Related Values 2010 Guidance Document for
Prevention of Significant Deterioration permitting (SO2,
NOX, PM10, and H2SO4
combined Q/d greater than 10). Alaska submission, Combined Section
III.K.13, Page III.K.13.F-11.
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We note that, as stated in the clarification letter, the 2022
regional haze plan submission used 2017 emissions inventory data to
select the University of Alaska Fairbanks Campus Power Plant as a
source for further evaluation, based on a Q/d value of 1.4. However,
the submission failed to account for the fact that, in 2019, the
original coal-fired boilers at the power plant were replaced with a
new, circulating fluidized bed coal-fired boiler equipped with a
limestone injection system to control SO2 emissions.\89\ The
source's 2020 SO2 emissions as reported to the 2020 National
Emissions Inventory were approximately 20.6 tons, and 2023 emissions
were just 7.4 tons.\90\ Because the source is estimated to be 117
kilometers from Denali National Park, the updated Q/d values for the
University of Alaska Fairbanks Campus Power Plant for both 2020 and
2023 fall below the State's screening threshold of 1.0.\91\ Accounting
for this update, the final sources selected by Alaska for further
analysis are listed in the following Table 4.
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\89\ See https://www.uaf.edu/campusmap/for-visitors/buildings/combined-heat-and-power-plant.php/.
\90\ See https://echo.epa.gov/.
\91\ 20.6 tons divided by 117 kilometers equals 0.2 Q/d, which
is less than 1.0 Q/d. 7.4 tons divided by 117 kilometers equals 0.1
Q/d, which is less than 1.0 Q/d.
\92\ Source: Alaska submission, Combined Section III.K.13, Table
III.K.13.F-8.
Table 4--Alaska Selected Sources \92\
----------------------------------------------------------------------------------------------------------------
Distance (d) 2017 SO2 (Q)
Source Class I area (km) (tpy) SO2 Q/d
----------------------------------------------------------------------------------------------------------------
Healy Power Plant..................... Denali National Park.... 6 296.4 49.4
Eielson Combined Heating and Power Denali National Park.... 133 262.8 2.0
Plant.
Chena Power Plant..................... Denali National Park.... 119 627.6 5.3
Fort Wainwright Central Heating and Denali National Park.... 119 460.0 3.9
Power Plant.
North Pole Power Plant................ Denali National Park.... 122 247.2 2.0
----------------------------------------------------------------------------------------------------------------
[[Page 48866]]
As shown in table 4 of this document, the sources selected by
Alaska are all power plants with potential visibility impacts at Denali
National Park. While Alaska also reviewed sources near the Tuxedni and
Simeonof Wilderness Areas, the sources reviewed emitted very little
SO2 and therefore, after applying the source selection
methodology used by the State, the sources near the Tuxedni and
Simeonof Wilderness Areas screened out.\93\ We note there are no
sources located near the Bering Sea Wilderness Area because it is
extremely remote, undeveloped, and far from industrial activity and
human populations.
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\93\ For example, the largest emitting facility near Tuxedni
Wilderness emitted 44.7 tons of SO2 in 2017 and the
largest emitting facility near Simeonof Wilderness emitted 2.8 tons
of SO2 in 2017. Alaska submission, Combined Section
III.K.13, Page III.K.13.F-7.
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In the regional haze plan submission, Alaska further supported its
source selection by reviewing broader source sectors, including the oil
and gas and marine sectors.\94\ The main oil and gas facilities in
Alaska are in the Cook Inlet and on the North Slope. The Cook Inlet oil
and gas platforms are closest to the Tuxedni Wilderness Area, however
the submission documented that these platforms already fire low-sulfur
fuel gas and ultra-low sulfur diesel (ULSD), and because of low actual
SO2 emissions, none were selected using the State's source
selection methodology.\95\ The North Slope is extremely remote and
distant from Alaska's Class I areas, and these facilities are generally
categorized as major stationary sources because they are not connected
to a grid and must generate their own power.\96\ Due to high distance
(d) and low emissions (Q), no oil and gas facilities were selected
using the State's source selection methodology.\97\ Alaska also noted
that commercial marine shipping fuels, as well as aviation and railroad
fuels, are regulated at the Federal level.\98\ The submission
highlighted that recently-implemented Federal and international
commercial marine shipping sulfur in fuel restrictions are significant
and have the potential to improve visibility in Alaska's Class I areas.
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\94\ Alaska submission, Section III.K.13, Combined Sections,
Page III.K.13.H-12.
\95\ Id., Page III.K.13.F-8 through F-11 and Alaska submission,
Appendix III.K.13.F.
\96\ Final Report: 2028 Future Year Oil and Gas Emission
Inventory for WESTAR-WRAP States--Scenario #1: Continuation of
Historical Trends, by John Grant, Rajashi Parikh, Amnon Bar-Ilan,
Ramboll US Corporation. October 2019.
\97\ Alaska submission, Combined Section III.K.13, Pages
III.K.13.H-13 and H-14.
\98\ Id., Pages III.K.H-24 and H-25.
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Based on a review of the information provided in the submission, we
propose to determine that Alaska adequately documented its review of
sources and source selection methodology consistent with 40 CFR
51.308(f)(2)(i).\99\
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\99\ See EPA 2019 Guidance at pages 27 and 28.
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3. Alaska Control Analyses and Determinations
As stated previously, to address the four statutory factors, the
Alaska 2022 regional haze plan relied in part on SO2 BACT
analyses originally conducted and submitted as part of the Fairbanks
PM2.5 serious nonattainment plan in 2020 and 2021.\100\ In
2024, Alaska submitted revisions to the SO2 BACT analyses to
address EPA concerns and to account for more recent vendor quotes and
fuel prices.\101\ Alaska indicated in the 2025 clarification letter
that the updated SO2 BACT analyses were also intended to
satisfy the regional haze four-factor analysis requirements.
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\100\ Determinations of Attainment by the Attainment Date,
Determinations of Failure To Attain by the Attainment Date and
Reclassification for Certain Nonattainment Areas for the 2006 24-
Hour Fine Particulate Matter National Ambient Air Quality Standards,
published May 10, 2017 (82 FR 21711).
\101\ The EPA's concerns were detailed in the Agency's proposed
disapproval of the plan on January 10, 2023, at 88 FR 1454.
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Consistent with the EPA 2019 Guidance, it is appropriate for a
State to rely on recent SO2 BACT analyses to also satisfy
regional haze four-factor analysis requirements.\102\ A BACT analysis
is a rigorous pollution control technology review process that makes
use of data acquired through vendor quotes and other means to review
and select technologically-feasible and cost-effective control
technology.\103\ Such an analysis is based on a number of factors,
including those factors addressed under regional haze--the costs of
compliance, the time necessary for compliance, the energy and non-air
quality environmental impacts of compliance, and the remaining useful
life of any potentially affected sources.\104\ We note that an
important difference between a BACT analysis and a regional haze four-
factor analysis for a source is that a BACT analysis is based on a
source's potential to emit a particular pollutant, while a four-factor
analysis is most often based on a source's actual emissions of that
pollutant, which is often lower.\105\ For that reason, regional haze
four-factor analyses tend to yield higher cost estimates per ton of
pollutant removed.
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\102\ EPA 2019 Guidance at page 23.
\103\ See 40 CFR 52.21(b)(12); 40 CFR 52.21(j); 40 CFR 51.1000
(``best available control measure''); U.S. EPA, Office of Air
Quality Planning and Standards, New Source Review Workshop Manual,
DRAFT, October 1990 at B.1 (``NSR Workshop Manual'').
\104\ Id. See also 40 CFR 51.1010(a).
\105\ See NSR Workshop Manual at B.37; EPA 2019 Guidance at 29.
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The following paragraphs describe the State's analysis for each
selected source and the EPA's evaluation against the requirements of
the CAA and the EPA's RHR. We are proposing to concur with Alaska's
finding that, because no retrofit SO2 controls are cost
effective for regional haze purposes, existing effective SO2
controls are already in place, and SO2 emissions are
unlikely to change over time, no SO2 controls are necessary
for reasonable progress in the regional haze second implementation
period.
a. Healy Power Plant
i. Background
The Healy Power Plant is an electric generating facility owned and
operated by the Golden Valley Electric Association (GVEA), a power-
generating cooperative serving interior Alaska. The plant, part of an
isolated system operating without connection to an interstate
transmission grid, combusts subbituminous coal from the nearby Usibelli
Coal Mine. In 2017, the plant emitted 296 tons of SO2.\106\
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\106\ From the 2017 National Emissions Inventory, available at
https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data/.
---------------------------------------------------------------------------
The primary units at the Healy Power Plant are two coal-fired steam
generators, a 25-megawatt (MW) Foster-Wheeler boiler installed in 1967
(Emissions Unit (EU) 1) and a 54-MW TRW Integrated Entrained Combustion
System installed in 1997 and commercially operated starting in 2018 (EU
2). EU 1 was subject to BART requirements for the first regional haze
implementation period.\107\ The EPA approved Alaska's determination
that the existing SO2 controls, specifically the requirement
to limit SO2 to 0.30 lb/MMBtu (30-day rolling average) using
the existing dry sorbent injection (DSI) system, constituted BART for
EU 1 (78 FR 10546, February 14, 2013).\108\
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\107\ EU 2 was not subject to BART.
\108\ The BART determination addressed nitrogen oxides,
particulate matter and sulfur dioxide. The BART cost estimate for EU
1 was $29,813 per ton of sulfur dioxide removed for installing and
operating a new spray dry absorber system, and $12,033 per ton of
sulfur dioxide removed for installing and operating a new wet
scrubber system. The cost of optimizing the existing dry sorbent
injection system on EU 1 was $4,218 per ton of sulfur dioxide
removed.
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EU 2, originally called the Healy Clean Coal Project, was developed
as a demonstration project in partnership
[[Page 48867]]
with the Alaska Legislature, the Alaska Industrial Development and
Export Authority (a public corporation of the State of Alaska), and the
U.S. Department of Energy Clean Coal Technology Program.\109\ The
construction of EU 2 was completed in 1997 and first fired coal in
1998, however operations were soon suspended due to technical and
operational issues.\110\ EU 2 began supplying power commercially in
2018.\111\
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\109\ See https://www.gvea.com/services/energy/sources-of-power/healy-power-plants/.
\110\ See Healy Operating Permit AQ0173TV03 at page 3, in the
Alaska submission, Appendix III.K.13.F-Part 2.
\111\ See https://www.gvea.com/services/energy/sources-of-power/healy-power-plants/.
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We note that, in 2012, GVEA and the Alaska Industrial Development
and Export Authority became subject to a Federal consent decree
concerning prevention of significant deterioration (PSD) program
applicability.\112\ If EU 1 continued to operate past 2024, the unit
was to be retrofitted with selective catalytic reduction technology to
limit NOX emissions to 0.070 lb/MMBtu (30-day rolling
average).\113\ The consent decree also required the continued operation
of the existing DSI system on EU 1 to limit SO2 emissions to
0.30 lb/MMBtu (30-day rolling average).\114\ For EU 2, the consent
decree required the installation of selective catalytic reduction
technology to limit NOX emissions and the continued
operation of the existing spray dry absorber system to limit
SO2 emissions to 0.10 lb/MMBtu (30-day rolling
average).\115\
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\112\ United States v. Golden Valley Electric Association and
Alaska Industrial Development and Export Authority, No. 4:12-cv-
00025, Consent Decree, November 19, 2012. Alaska submission,
Appendix III.K.13.F-Part 2.
\113\ Or an alternative nitrogen oxide control technology
approved by the EPA.
\114\ United States v. Golden Valley Electric Association and
Alaska Industrial Development and Export Authority, No. 4:12-cv-
00025, Consent Decree, November 19, 2012. See also condition 44 of
Healy Operating Permit AQ0173TVP03. Alaska submission, Appendix
III.K.13.F-Part 2.
\115\ Id. See also condition 45 of Healy Operating Permit
AQ0173TVP03. Alaska submission, Appendix III.K.13.F-Part 2.
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ii. Alaska Control Determination
For EU 1, Alaska determined that the unit was effectively
controlled, and that it could be excluded from additional control
measure review because: (1) the unit was already equipped with DSI
technology and (2) the unit already went through a comprehensive BART
analysis during the first implementation period.\116\
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\116\ Alaska submission, Combined Section III.K.13, at page 27;
See October 6, 2025, clarification letter in the docket for this
action.
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Alaska relied on the prior BART analysis to determine that
additional controls on EU 1 are not necessary for reasonable progress
in the second planning period. In the prior BART determination, Alaska
evaluated three SO2 controls: spray dry absorbers, wet
scrubbers, and DSI optimization. The State estimated that the
incremental cost effectiveness for the addition of a spray dry absorber
system was $29,813 per ton of SO2 removed and for a wet
scrubber system was $12,033 per ton of SO2 removed. Alaska
estimated that optimization of the DSI system on EU 1 would cost $4,218
per ton of SO2 removed.
Alaska speculated that DSI system optimization may be cost-
effective upon reevaluation or, alternatively, the unit could meet a
0.20 lb/MMBtu limit without additional controls based on average actual
SO2 emission rate.\117\ Therefore, if EU 1 continued to
operate, the State provided GVEA with the option to further evaluate
optimizing the DSI system, or to take a lower SO2 limit
(0.20 lb/MMBtu (30-day rolling average)).\118\
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\117\ Ibid. The State based this preliminary finding on the BART
analysis conducted during the first implementation period and a
review of 2017 through 2019 National Emissions Inventory data
collected by the existing continuous emissions monitoring system
(CEMS). Alaska found that the average actual SO2 emission
rate for EU 1 was 0.26 lb/MMBtu over this time period.
\118\ Alaska submission, Appendix III.K.13.F-Part 2.
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Subsequent to the 2022 regional haze plan submission, GVEA elected
to install selective catalytic reduction on EU 1 and continue operating
the unit. Accordingly, Alaska and GVEA evaluated the feasibility of EU
1 meeting a lower SO2 limit. Alaska determined that EU 1
cannot meet a 0.20 lb/MMBtu SO2 limit without additional
controls or optimizing the existing DSI system.\119\ Additionally,
Alaska determined that optimizing the DSI system was not necessary for
reasonable progress during the second planning period.
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\119\ See October 6, 2025, clarification letter in the docket
for this action, enclosure at page 17.
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The Alaska DEC stated in the clarification letter that the
SO2 BACT analyses conducted under the Fairbanks
PM2.5 nonattainment plan corroborated what Alaska had found
in the prior BART determination for EU 1--that additional
SO2 reductions would be cost prohibitive. Information in the
updated 2024 SO2 BACT analyses confirmed the State's prior
determination that a DSI system optimization and retrofit project would
not be cost-effective. The State reasoned that optimizing the existing
DSI system would have comparable cost effectiveness values to
installation of a new system because the total cost would be lower, but
the optimized system would not be capable of achieving control
efficiencies as high as a new system.\120\ Therefore, Alaska determined
that the cost effectiveness of optimizing the existing DSI system
ranged from over $15,000 per ton of SO2 removed to over
$34,000 per ton of SO2 removed.\121\
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\120\ See October 6, 2025, clarification letter in the docket
for this action, enclosure at pages 19 and 20.
\121\ Id.
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According to Alaska, this information supports a finding that EU 1
remains effectively controlled using the existing DSI system to limit
SO2 to 0.30 lb/MMBtu (30-day rolling average), as specified
in the Federal consent decree and as approved as BART in the Alaska
regional haze first implementation period plan.\122\ Alaska estimated a
four-year timeframe to optimize the existing DSI system.\123\ The State
considered the energy and non-air quality environmental impacts of
compliance by including electricity cost attribution, potential for
formation of a brown plume from increased sodium bicarbonate injection
and additional waste disposal costs. Alaska also considered the
remaining useful life of the controls by assuming a 30-year equipment
life.\124\
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\122\ United States v. Golden Valley Electric Association and
Alaska Industrial Development and Export Authority, No. 4:12-cv-
00025, Consent Decree, November 19, 2012. See also condition 44 of
Healy Operating Permit AQ0173TVP03. Alaska submission, Appendix
III.K.13.F-Part 2.
\123\ See October 6, 2025, clarification letter, in the docket
for this action, letter at page 4.
\124\ State Air Quality Control Plan, Vol. II, Appendix
III.D.7.7-176-182 at https://www.regulations.gov/document/EPA-R10-OAR-2024-0595-0078 or see file
127_State_Submission_BACT_Analysis_11_5_2024.pdf at pages 176-182 in
the docket for this action.
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Regarding EU 2, Alaska concluded that the unit remained effectively
controlled using the existing spray dry absorber system to limit
SO2 emissions to 0.10 lb/MMBtu (30-day rolling average), as
specified in the Federal consent decree.\125\
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\125\ Alaska submission, Combined Section III.K.13, Table
III.K.13.F-22 (Final Determination for GVEA--Healy Power Plant).
---------------------------------------------------------------------------
iii. EPA Evaluation
For EU 1, we concur with the State's finding that the unit is
effectively controlled and that optimizing the existing SO2
controls to meet a lower SO2 emission limit is not necessary
for reasonable progress in the second implementation period. Alaska
considered the four statutory factors in making this finding. Alaska
reviewed its prior BART cost estimate and more recent information
gleaned from the Fairbanks BACT analyses, which were
[[Page 48868]]
based on vendor quotes and methods consistent with the EPA Air
Pollution Control Cost Manual. The State considered the energy and non-
air quality environmental impacts of compliance by including
electricity cost attribution, potential for formation of a brown plume
from increased sodium bicarbonate injection and additional waste
disposal costs. Alaska used a 30-year equipment life in its cost
calculations.\126\
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\126\ See October 6, 2025, clarification letter in the docket
for this action, enclosure at page 19.
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Alaska estimated the time necessary for compliance to be at least
four years. Alaska reasonably assumed that GVEA would time any upgrade
to the DSI system to coincide with work on the unit to install
activated carbon injection ports to ensure compliance with the MATS.
Importantly, the requirement to continue operating the DSI system to
meet the associated SO2 limit of 0.30 lb/MMBtu (30-day
rolling average) on EU 1 is embodied in a Federal consent decree and
title V operating permit and was previously approved by the EPA as
BART.
For EU 2, we concur with the State's finding that the requirement
to continue operating the spray dry absorber system to meet the
associated SO2 limit of 0.10 lb/MMBtu (30-day rolling
average) on EU 2 is an existing effective control, because it is a
BACT-level control established as part of a Federal consent decree to
resolve issues around PSD applicability.\127\ The BACT process takes
into consideration the cost of the control, the time necessary to
install the control, the non-air quality impacts of the control, and
the remaining useful life of the control.\128\ The requirement remains
embodied in a Federal consent decree and title V operating permit.\129\
---------------------------------------------------------------------------
\127\ EPA 2019 guidance at pages 22 and 23.
\128\ 40 CFR 52.21(b)(12); NSR Workshop Manual, at B.6.
\129\ United States v. Golden Valley Electric Association and
Alaska Industrial Development and Export Authority, No. 4:12-cv-
00025, Consent Decree, November 19, 2012. See also conditions 44 and
45 of Healy Operating Permit AQ0173TVP03. See also Alaska
submission, Appendix III.K.13.F-Part 2.
---------------------------------------------------------------------------
b. Eielson Combined Heating and Power Plant
i. Background
The Eielson Air Force Base is located 26 miles southeast of
Fairbanks and is comprised of an airfield, housing, office buildings,
and supporting facilities. The Eielson Combined Heating and Power Plant
is a co-generation plant that provides heat and power to the base. The
plant combusts subbituminous coal from the Usibelli Coal Mine and
emitted 263 tons of SO2 in 2017.\130\
---------------------------------------------------------------------------
\130\ From the 2017 National Emissions Inventory, available at
https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data.
---------------------------------------------------------------------------
The Eielson Combined Heating and Power Plant originally included
six stoker type coal-fired boilers, each rated at 160 MMBtu/hr,
installed in 1952. In 2010, the Alaska DEC permitted the U.S. Air Force
to replace the original boilers in phases. Two of the six original
boilers were replaced with modern coal-fired boilers in 2014 and 2016
(EUs 5A and 6A).\131\ EUs 5A and 6A are equipped with a DSI system
using sodium bicarbonate and are required to limit SO2 to
0.20 lb/MMBtu (30-day rolling average), consistent with the Federal New
Source Performance Standard for Industrial-Commercial-Institutional
Steam Generating Units.\132\ Four of the original 1950s era boilers
continue to operate (EUs 1 through 4).
---------------------------------------------------------------------------
\131\ See Minor Permit AQ0264MSS05, issued August 9, 2010, in
the docket for this action. According to the Alaska submission, the
U.S. Air Force estimated that all six boilers would be replaced by
2020. To date, two of the boilers were replaced. See Alaska
submission, Combined Section III.K.13, Pages III.K.13.F-32 through
F-40.
\132\ 40 CFR part 60, subpart Db. Eielson Air Force Base, Air
Quality Operating Permit No. AQ0264TVP02, April 15, 2013, Condition
54.
---------------------------------------------------------------------------
ii. Alaska Control Determination
For EUs 1 through 4, Alaska provided the U.S. Air Force the option
to continue the boiler replacement project, to be completed by December
31, 2024, or submit a four-factor analysis that evaluated retrofit wet
scrubbers, spray dry absorber, and DSI systems.\133\ The State's
clarification letter indicated that the U.S. Air Force submitted a
general four-factor analysis concluding that no retrofit SO2
retrofit controls were cost-effective. DEC revised the cost analyses
by: (1) using EPA's April 2024 Retrofit Cost Tool spreadsheet; (2)
assuming a retrofit factor of 1.0, (3) assuming a control efficiency of
95% for a wet scrubber and a spray dry absorber, and 98% for DSI, (4)
using a waste disposal cost of $30 per ton, and (5) using an operating
labor rate of $60 per hour.\134\ Using these factors, DEC determined
that the cost effectiveness of a wet scrubber and a spray dry absorber
exceeded $50,000 per ton of SO2 removed. DEC also determined
that DSI had a cost effectiveness of over $12,000 per ton.\135\
---------------------------------------------------------------------------
\133\ Alaska submission, Combined Section III.K.13, Table
III.K.13.F-30.
\134\ See October 6, 2025, clarification letter in the docket
for this action, enclosure at pages 34 and 35.
\135\ Id. at page 35.
---------------------------------------------------------------------------
Alaska DEC also compared these cost analyses with the updated
SO2 BACT analysis for similar 1950s era stoker type coal-
fired boilers for the nearby Fort Wainwright Central Heating and Power
Plant (EUs 1 through 6) that the State recently submitted to the EPA as
part of the Fairbanks PM2.5 serious nonattainment area plan.
The Fort Wainwright updated SO2 BACT analysis, which was
reviewed by the EPA, revised according to EPA comments, and ultimately
included conservative assumptions and recent vendor quotes, considered
the cost of compliance, the time necessary for compliance, the energy
and non-air quality impacts, and the remaining useful life of the
controls.\136\ Specifically, Alaska considered the time necessary for
compliance to be less than one year for dry sorbent injection and spray
dry absorber systems, and approximately three years for a wet flue gas
desulfurization system.\137\ The State also considered the energy and
non-air quality environmental impacts of operating the controls,
including electricity cost attribution, potential for formation of ice
fog, and possible need for waste and wastewater disposal, and remaining
useful life of the controls as estimated in the BACT analysis (30-year
equipment life).\138\
---------------------------------------------------------------------------
\136\ See State Air Quality Control Plan, Vol. II, Appendix
III.D.7.7-225-229 at https://www.regulations.gov/document/EPA-R10-OAR-2024-0595-0078 or see file
127_State_Submission_BACT_Analysis_11_5_2024.pdf at pages 225-229 in
the docket for this action.
\137\ Id.; See October 6, 2025, clarification letter in the
docket for this action, enclosure at pages 35 and 36.
\138\ Id.
---------------------------------------------------------------------------
Alaska found that dry sorbent injection constituted SO2
BACT at a cost effectiveness of $6,636 per ton of SO2
removed, based on potential to emit.\139\ Alaska also found that the
cost effectiveness of retrofitting with circulating dry scrubbers, wet
flue gas desulfurization, and spray dry absorbers ranged from over
$13,000 per ton to over $20,000 per ton of SO2 removed based
on potential to emit. As stated in the clarification letter, because
the SO2 BACT analysis was based on the potential to emit
1,470 tons of SO2 combined from Fort Wainwright EUs 1
through 6, the retrofit costs for Eielson EUs 1 through 4 would be even
higher based on lower actual emissions (212 tons of SO2
combined).\140\ Alaska therefore concluded that retrofitting Eielson
EUs 1 through 4 with any SO2 controls would be cost
prohibitive for the regional haze second implementation period.
---------------------------------------------------------------------------
\139\ Id.
\140\ 2023 actual emissions.
---------------------------------------------------------------------------
For Eielson EUs 5A and 6A, Alaska determined that the existing
SO2 limit of
[[Page 48869]]
0.20 lb/MMBtu (30-day rolling average) is an existing effective
control.\141\ Alaska further concluded that, while it may be
technically feasible to improve the efficiency of the existing DSI
system, actual emissions from EUs 5A and 6A have been extremely low
(5.9 tons in 2017, 22 tons in 2018, and 3.7 tons in 2019), and
therefore work to further reduce emissions would not be cost-
effective.\142\ Alaska stated in the clarification letter that the 0.20
lb/MMBtu (30-day rolling average) limit is not necessary for reasonable
progress because actual emissions from EUs 5A and 6A have been
consistently low with little variation and because the limit is already
embodied in the Federal New Source Performance Standard for Industrial-
Commercial-Institutional Steam Generating Units.\143\
---------------------------------------------------------------------------
\141\ Alaska submission, Combined Section III.K.13, Table
III.K.13.F-30.
\142\ Id.
\143\ 40 CFR part 60, subpart Db. Eielson Air Force Base, Air
Quality Operating Permit No. AQ0264TVP02, April 15, 2013, Condition
54; See October 6, 2025, clarification letter in the docket for this
action, enclosure at page 37.
---------------------------------------------------------------------------
iii. EPA Evaluation
For Eielson EUs 1 through 4, we propose to approve the State's
finding that no SO2 controls are necessary for reasonable
progress, based on the State's consideration of the four factors.
Alaska considered cost by conducting new analyses and reviewing BACT
analysis data for similar units at the nearby Fort Wainwright.\144\ As
discussed in the preceding paragraphs, Alaska considered the cost of
compliance, time necessary for compliance, the energy and non-air
quality environmental impacts of compliance, and remaining useful life
of the controls.\145\ The BACT process takes into consideration the
cost of the control, the time necessary to install the control, the
non-air quality impacts of the control, and the remaining useful life
of the control.\146\
---------------------------------------------------------------------------
\144\ See the Fort Wainwright Central Heating and Power Plant
SO2 reduction analysis report, May 21, 2021, in the
docket for this action or at https://www.regulations.gov/document/EPA-R10-OAR-2022-0115-0251 and State Air Quality Control Plan, Vol.
II, Appendix III.D.7.7-225-229 at https://www.regulations.gov/document/EPA-R10-OAR-2024-0595-0078 or see file
127_State_Submission_BACT_Analysis_11_5_2024.pdf at pages 225-229 in
the docket for this action.
\145\ Ibid.
\146\ 40 CFR 52.21(b)(12); NSR Workshop Manual, at B.6.
---------------------------------------------------------------------------
With respect to EUs 5A and 6A, we concur with the State's finding
that the existing requirement to limit SO2 emissions to 0.20
lb/MMBtu (30-day rolling average) is not necessary for reasonable
progress. These units are currently subject to the applicable
SO2 limit in the Federal New Source Performance Standard for
Industrial-Commercial-Institutional Steam Generating Units.\147\ Actual
emissions from EUs 5A and 6A have been consistently low with little
variation, therefore, we expect SO2 emissions from EUs 5A
and 6A are unlikely to increase over time. Between 2014 and 2019,
SO2 emissions from all coal-fired boilers at Eielson ranged
between 211.77 tons per year and 267.3 tons per year, with a general
downward trend.\148\ In addition, EUs 1-4 and 5A and 6A are subject to
a coal combustion limit of 220,000 tons per 12 consecutive months.\149\
---------------------------------------------------------------------------
\147\ 40 CFR part 60, subpart Db; Eielson Air Force Base, Air
Quality Operating Permit No. AQ0264TVP02, April 15, 2013, Condition
54.
\148\ See October 6, 2025, clarification letter in the docket
for this action, enclosure at page 30.
\149\ Air Quality Operating Permit, Permit No. AQ0264TVP02, Rev.
2, November 10, 2014, Condition 35.1. This condition effectively
caps the SO2 emissions from the central heat and power
plant. Note, Eielson requested this limit to avoid classification as
a major source of hazardous air pollutants.
---------------------------------------------------------------------------
c. Chena Power Plant
i. Background
The Chena Power Plant is a co-generation plant owned and operated
by Aurora Energy, LLC. The plant, part of an isolated power-generating
system operating without connection to an interstate transmission grid,
fires subbituminous coal from the Usibelli Coal Mine and emitted 628
tons of SO2 in 2017.\150\ The Chena Power Plant consists of
four coal-fired boilers (EUs 4 through 7) that produce steam for
district heating and electricity in the city of Fairbanks. EUs 4, 5,
and 6, installed in the early 1950s, are overfeed traveling grate
stoker type boilers rated at 76 MMBtu/hr each. EU 7, installed in 1970,
is a spreader-stoker type boiler rated at 269 MMBtu/hr. EUs 4 through 7
were subject to SO2 BACT as part of the Fairbanks
PM2.5 nonattainment area plan, as summarized in the
following paragraphs.
---------------------------------------------------------------------------
\150\ From the 2017 National Emissions Inventory, available at
https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data/.
---------------------------------------------------------------------------
ii. Alaska Control Determination
For EUs 4 through 7, Alaska determined based on recent
SO2 BACT analyses that no retrofit SO2 controls
at Chena Power Plant EUs 4 through 7 are necessary for reasonable
progress in the second implementation period. Alaska relied on the
SO2 BACT analysis conducted for these units as part of the
Fairbanks PM2.5 nonattainment area plan \151\ to also
satisfy the regional haze plan four-factor analysis requirements.\152\
The Alaska 2022 regional haze plan pointed to the original
SO2 BACT control analysis and determination (limiting the
sulfur content of coal fired in EUs 4 through 7 to 0.25% sulfur by
weight and limiting SO2 emissions from EUs 4 through 7 to no
more than 0.301 lb/MMBtu (3-hour average)).\153\ However, the Alaska
DEC subsequently withdrew the original SO2 BACT analysis
included in the Fairbanks PM2.5 nonattainment area
plan.\154\
---------------------------------------------------------------------------
\151\ Fairbanks PM2.5 serious area SIP revisions
submitted on December 13, 2019, and December 15, 2020.
\152\ Alaska submission, Combined Section III.K.13, Pages
III.K.13.F-29 through 32.
\153\ Id., Pages III.K.13.F-29 through 32.
\154\ See Alaska BACT withdrawal letter dated September 26,
2023, in the docket for this action.
---------------------------------------------------------------------------
On December 4, 2024, Alaska submitted revisions to the Fairbanks
PM2.5 nonattainment area plan that updated the original
SO2 BACT analysis for Chena Power Plant EUs 4 through 7,
among other elements.\155\ The SO2 BACT analysis --which was
reviewed by the EPA, revised according to EPA comments, and ultimately
included conservative assumptions and recent vendor quotes--considered
the cost of compliance, the time necessary for compliance, the energy
and non-air quality impacts, and the remaining useful life of the
controls.\156\ Specifically, Alaska considered the time necessary for
compliance to be one year for dry sorbent injection and spray dry
absorber systems, and three years for a wet flue gas desulfurization
system.\157\ The State also considered the energy and non-air quality
environmental impacts of operating the controls, including ash disposal
and wastewater disposal requirements, and remaining useful life of the
controls as estimated in the BACT analysis (30-year equipment
life).\158\ The updated BACT analysis indicated that the least costly
SO2 control, DSI, was estimated to cost $13,368 per ton of
SO2 reduced, based on potential to emit.\159\ The updated
analysis also indicated that wet flue gas desulfurization and spray dry
absorbers would be more costly. Alaska therefore concluded that
additional SO2 controls
[[Page 48870]]
were not economically feasible as BACT.
---------------------------------------------------------------------------
\155\ State Air Quality Control Plan, Vol. II, Appendix
III.D.7.7-176-182 at https://www.regulations.gov/document/EPA-R10-OAR-2024-0595-0078 or see file
127_State_Submission_BACT_Analysis_11_5_2024.pdf at pages 176-182 in
the docket for this action.
\156\ Ibid.
\157\ Ibid.
\158\ Ibid.
\159\ Ibid.
---------------------------------------------------------------------------
Based on the updated SO2 BACT analysis, Alaska found no
retrofit SO2 controls at Chena Power Plant EUs 4 through 7
to be necessary for reasonable progress in the second implementation
period.
iii. EPA Evaluation
Relying on recent SO2 BACT analyses to also satisfy
regional haze requirements is appropriate and consistent with the EPA
2019 Guidance.\160\ We concur with the State's finding that no
SO2 controls are necessary for reasonable progress, based on
the State's reasonable consideration of the four factors. Alaska's BACT
analysis for dry sorbent injection is based on a site-specific vendor
cost estimate.\161\ Additionally, the State noted that there is limited
available land at the power plant for construction of larger
SO2 controls, such as wet scrubbers.\162\ As part of its
SO2 BACT analysis described in the previous paragraphs, the
State considered the energy and non-air quality impacts of installing
dry sorbent injection, the time necessary to install the controls, and
the remaining useful life of the controls. We acknowledge that the 2022
regional haze plan indicated the State's original SO2 BACT
coal sulfur limit also satisfied reasonable progress requirements,
however, we believe this coal sulfur limit is not necessary for
reasonable progress, because the plant burns coal exclusively from the
Usibelli Coal Mine in Healy, Alaska. The coal sulfur content is thus
inherent to the type of coal from this mine.\163\
---------------------------------------------------------------------------
\160\ At page 23.
\161\ State Air Quality Control Plan, Vol. II, Appendix
III.D.7.7-176-182 at https://www.regulations.gov/document/EPA-R10-OAR-2024-0595-0078 or see file
127_State_Submission_BACT_Analysis_11_5_2024.pdf at pages 176-182 in
the docket for this action.
\162\ Ibid.
\163\ State Air Quality Control Plan, Appendix III.D.7.7-75
(``the Usibelli Coal Mine is the source of all coal marketed and
burned in Fairbanks. Their factsheet73 indicates the sulfur content
of coal from the Healy mine is typically 0.2% with a range of 0.08%-
0.28%. The Healy mine supplies the coal burned in Fairbanks.'').
---------------------------------------------------------------------------
d. Fort Wainwright Central Heating and Power Plant
i. Background
Fort Wainwright is a U.S. Army base located in Fairbanks, Alaska.
The Fort Wainwright Central Heating and Power Plant provides heat and
power to the base. The plant combusts subbituminous coal from the
Usibelli Coal Mine and emitted a total of 460 tons of sulfur dioxide in
2017.\164\
---------------------------------------------------------------------------
\164\ From the 2017 National Emissions Inventory, available at
https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data/.
---------------------------------------------------------------------------
The Fort Wainwright Central Heating and Power Plant is made up of
six spreader-stoker type coal-fired boilers installed in 1953, each
rated at 230 MMBtu/hr, that produce steam to heat and power the base
(EUs 1 through 6). The plant is owned and operated by Doyon Utilities,
LLC, a subsidiary of Doyon Limited, the regional Alaska Native
corporation for Interior Alaska. EUs 1 through 6 were subject to
SO2 BACT as part of the Fairbanks PM2.5
nonattainment area plan, as summarized in the following paragraphs.
ii. Alaska Control Determination
For EUs 1 through 6, Alaska determined based on recent
SO2 BACT analyses conducted for these units as part of the
Fairbanks PM2.5 nonattainment area plan \165\ that no
SO2 emissions controls are necessary for reasonable
progress. Alaska based this decision on SO2 BACT
determinations included in its latest SIP submission for the Fairbanks
PM2.5 Nonattainment area. Prior to this SIP submission,
Alaska had determined that installation of a new dry sorbent injection
system to meet a 0.12 lb/MMBtu SO2 emissions limit (averaged
over a 3-hour period) was BACT for EUs 1 through 6. In its 2022
regional haze plan submission, Alaska purported to rely on this prior
SO2 BACT determination to satisfy, in part, regional haze
requirements on EUs 1 through 6.\166\ However, the Alaska DEC withdrew
the SO2 BACT analysis.\167\
---------------------------------------------------------------------------
\165\ Fairbanks PM2.5 serious area SIP revisions
submitted on December 13, 2019, and December 15, 2020.
\166\ Ibid.
\167\ See Alaska BACT withdrawal letter dated September 26,
2023, in the docket for this action.
---------------------------------------------------------------------------
On December 4, 2024, Alaska submitted revisions to the Fairbanks
PM2.5 nonattainment area plan that included an updated
SO2 BACT analysis for the Fort Wainwright Central Heating
and Power Plant EUs 1 through 6, among other elements.\168\
---------------------------------------------------------------------------
\168\ State Air Quality Control Plan, Vol. II, Appendix
III.D.7.7-202 at https://www.regulations.gov/document/EPA-R10-OAR-2024-0595-0078 or see file
127_State_Submission_BACT_Analysis_11_5_2024.pdf at page 202 in the
docket for this action.
---------------------------------------------------------------------------
The SO2 BACT analysis was reviewed by the EPA, revised
according to EPA comments, and ultimately included conservative
assumptions and recent vendor quotes.\169\ Based on the updated
analysis, Alaska concluded that dry sorbent injection constituted
SO2 BACT at a cost effectiveness of $6,636 per ton of
SO2 removed, based on potential to emit.\170\ The Alaska DEC
also found that the cost effectiveness of retrofitting with circulating
dry scrubbers, wet flue gas desulfurization, and spray-dry adsorbers
ranged from over $13,000 per ton to over $20,000 per ton of
SO2 removed based on potential to emit. In addition, as
stated in the clarification letter, because the Fort Wainwright
SO2 BACT analysis was based on the potential to emit 1,470
tons of SO2 combined from EUs 1 through 6, Alaska found that
the retrofit cost per ton reduced based on actual emissions would
triple.\171\ Alaska assumed a remaining useful life of 30 years for
circulating dry scrubbers, wet flue gas desulfurization, spray-dry
adsorbers, and dry sorbent injection.\172\ Regarding energy and non-air
quality impacts, the State determined that wet flue gas desulfurization
consumed the most energy due to reagent preparation, such as grinding
limestone.\173\ The dry systems (dry sorbent injunction and circulating
dry scrubbers) required additional energy due to pressure drop from
pulse jet fabric filters.\174\ According to Alaska, wet scrubbers also
demand significant water, which could lead to potential ice fog
formation.\175\ These systems also produce wastewater.\176\ The dry
systems have the potential to increase solid waste generation due to
sorbent disposal.\177\ Alaska considered the time necessary to install
controls to be less than one year for dry sorbent injection and spray
dry absorber systems, and approximately three years for a wet flue gas
desulfurization system, based on the BACT analysis.\178\ Alaska
ultimately found that retrofitting Fort Wainwright EUs 1 through 6 with
any SO2 controls would be cost prohibitive for the regional
haze second implementation period.
---------------------------------------------------------------------------
\169\ See State Air Quality Control Plan, Vol. II, Appendix
III.D.7.7-225-229 at https://www.regulations.gov/document/EPA-R10-OAR-2024-0595-0078 or see file
127_State_Submission_BACT_Analysis_11_5_2024.pdf at pages 225-229 in
the docket for this action.
\170\ Ibid.
\171\ See October 6, 2025, clarification letter in the docket
for this action, enclosure at page 42. 2023 actual emissions.
\172\ See Final CHPP SO2 Reduction Analysis Fort
Wainwright, B&V Project No. 406418, Prepared for Doyon Utilities, 25
August 2021 at ES-3, available at https://www.regulations.gov/document/EPA-R10-OAR-2022-0115-0249/.
\173\ Id. at 6-1.
\174\ Id.
\175\ Id. at 6-2--6-7.
\176\ Id. at 6-8.
\177\ Id. at 6-1; 6-8.
\178\ Ibid.
---------------------------------------------------------------------------
[[Page 48871]]
iii. EPA Evaluation
As stated previously, relying on recent SO2 BACT
analyses to also satisfy regional haze requirements is appropriate and
consistent with the EPA 2019 Guidance.\179\ We concur with the State's
finding that no SO2 controls are necessary for reasonable
progress, based on Alaska's reasonable evaluation of the four statutory
factors. Alaska considered cost by reviewing BACT analysis data
originally developed by the facility and updated by the State to
address EPA comments and to include recent vendor quotes for various
SO2 emissions controls, including dry sorbent injection and
wet flue gas desulfurization.\180\ Alaska considered the time necessary
to install controls to be less than one year for dry sorbent injection
and spray dry absorber systems, and approximately three years for a wet
flue gas desulfurization system, based on the BACT analysis.\181\ The
State also considered the energy and non-air quality environmental
impacts of operating the controls, including electricity cost
attribution, potential for formation of ice fog and possible need for
waste and wastewater disposal. Finally, Alaska determined the remaining
useful life of the controls as estimated in the BACT analysis (30-year
equipment life).\182\
---------------------------------------------------------------------------
\179\ EPA 2019 Guidance and page 23.
\180\ See the Fort Wainwright Central Heating and Power Plant
SO2 reduction analysis report, May 21, 2021, in the
docket for this action or at https://www.regulations.gov/document/EPA-R10-OAR-2022-0115-0251 and State Air Quality Control Plan, Vol.
II, Appendix III.D.7.7-225-229 at https://www.regulations.gov/document/EPA-R10-OAR-2024-0595-0078 or see file
127_State_Submission_BACT_Analysis_11_5_2024.pdf at pages 225-229 in
the docket for this action.
\181\ Ibid.
\182\ Ibid.
---------------------------------------------------------------------------
e. North Pole Power Plant
i. Background
The North Pole Power Plant is an electric generating facility owned
and operated by Golden Valley Electric Association (GVEA). The plant is
located in North Pole, near Fairbanks, and is part of an isolated
power-generating system operating without connection to an interstate
transmission grid. The plant combusts fuel oil supplied by the local
PetroStar Refinery and in 2017 emitted 247 tons of SO2.\183\
---------------------------------------------------------------------------
\183\ From the 2017 National Emissions Inventory, available at
https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data/.
---------------------------------------------------------------------------
The primary units at the North Pole Power Plant include two fuel
oil-fired GE Frame 7000 Series regenerative simple cycle gas combustion
turbines rated at 672 MMBtu/hr each (EUs 1 and 2) that burn high sulfur
diesel and two GE LM600PC combined cycle gas combustion turbines rated
at 455 MMBtu/hr each (EUs 5 and 6) that burn light straight run, a low
sulfur naphtha fuel. We note that EU 6 is not yet operational. EUs 1,
2, 5 and 6 were subject to SO2 BACT as part of the Fairbanks
PM2.5 nonattainment area plan, as summarized in the
following paragraphs.
ii. Alaska Control Determination
Based on the State's recent SO2 BACT analyses and
consideration of the four factors, Alaska determined that no
SO2 emission controls are necessary on EUs 1, 2, 5 or 6 in
the second planning period. In its 2022 regional haze plan submission,
Alaska relied in part on older SO2 BACT analysis conducted
and documented for EUs 1, 2, 5 and 6 as part of the Fairbanks
PM2.5 nonattainment area plan, as well as supplemental four
factor analyses to satisfy the regional haze requirements for the
second planning period. Specifically, Alaska previously determined the
following with respect to regional haze requirements at the North Pole
Power Plant:
EUs 1 and 2: Switching to Alaska No. 1 fuel oil (1000
ppmw) in EUs 1 and 2 from April through September was necessary for
reasonable progress (provided GVEA can purchase No. 1 fuel oil from the
Petro Star North Pole Refinery).\184\
---------------------------------------------------------------------------
\184\ Id. Page III.K.13.F-19. This finding is predicated on the
assumption that GVEA will be able to purchase No. 1 fuel oil from
the Petro Star North Pole Refinery. If the North Pole Refinery is
not able to supply GVEA with No. 1 fuel oil due to shortages in
supply, the North Pole Power Plant may continue to burn No. 2 fuel
oil in EUs 1 and 2 until such time as No. 1 fuel oil is again
available. The analysis also assumed that EUs 1 and 2 were already
subject to a now rescinded requirement to burn ULSD October through
March under Alaska Fairbanks PM2.5 nonattainment plan.
---------------------------------------------------------------------------
EUs 5 and 6: Switching from 50 ppmw sulfur naphtha or
light straight run to 15 ppmw ULSD in EUs 5 and 6 was not cost-
effective (greater than $1 million per ton SO2
removed).\185\
---------------------------------------------------------------------------
\185\ Based on actual emissions.
---------------------------------------------------------------------------
Based on updated SO2 BACT analyses, Alaska determined
that no controls at the North Pole Power Plant are necessary for
reasonable progress in the second planning period.
On December 4, 2024, as part of the revisions to the Fairbanks
PM2.5 nonattainment area plan to address the EPA's partial
disapproval action, Alaska included an updated SO2 BACT
analysis for North Pole Power Plant EUs 1 and 2, among other
elements.\186\ The Alaska DEC determined in this updated analysis that
requiring EUs 1 and 2 to fire ULSD would cost approximately $6,629 to
$13,932 per ton for EU 1 based on potential to emit and between $6,723
and $14,026 per ton for EU 2, depending on fuel price.\187\
---------------------------------------------------------------------------
\186\ See State Air Quality Control Plan, Vol. II, Appendix
III.D.7.7-301-307 at https://www.regulations.gov/document/EPA-R10-OAR-2024-0595-0078 or see file
127_State_Submission_BACT_Analysis_11_5_2024.pdf at pages 301-307 in
the docket for this action.
\187\ The documentation for this finding can be found at https://www.regulations.gov/document/EPA-R10-OAR-2024-0595-0078/.
---------------------------------------------------------------------------
The State also noted that there is no local supply of ULSD in
Fairbanks. Therefore, in order to comply with a requirement to burn
only ULSD in EUs 1, 2, 5 and 6, GVEA would have to source the ULSD from
southern Alaska, e.g., Valdez.\188\ Increased highway or rail trucking
of ULSD to Fairbanks increases on-road and rail air pollutant emissions
and the potential for fuel spills.\189\ Both of these could be
ameliorated by construction of a local tank farm. GVEA commissioned a
cost and feasibility study of constructing a tank farm as part of the
Fairbanks PM2.5 nonattainment area plan.\190\ The State
incorporated the capital costs from this estimate into its cost-
effectiveness calculations discussed previously. The Alaska DEC
determined that GVEA would need three years to comply with lower sulfur
fuel content requirements.\191\
---------------------------------------------------------------------------
\188\ See Response to Comments Regarding Best Available Control
Measure Requirements for Residential and Commercial Fuel Oil
Combustion, November 2. 2023 at 3-4, available at https://www.regulations.gov/document/EPA-R10-OAR-2022-0115-0379/.
\189\ Id. at 3-11.
\190\ GVEA Alternative BACT November 2018; Attachment 2
Technical Memo from PDC Regarding Bulk Fuel Storage available at
https://www.regulations.gov/document/EPA-R10-OAR-2022-0115-0252/.
\191\ State Air Quality Control Plan, III.D.7.7-79 (November 19,
2019) available at https://www.regulations.gov/document/EPA-R10-OAR-2022-0115-0076/.
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In the 2025 clarification letter, Alaska updated the cost analyses
based on the latest price per gallon of ULSD and No. 1 fuel oil. For
both EU 1 and EU 2, Alaska determined that switching to ULSD would have
a cost effectiveness of $29,646 per ton of SO2 removed and
switching to No. 1 fuel oil would have a cost effectiveness of $23,110
per ton of SO2 removed.\192\ Thus, according to Alaska, the
updated analysis showed that requiring either ULSD or No. 1 fuel oil
was not cost effective. The State also noted that Petro Star is unable
to supply GVEA with No. 1 fuel oil because it
[[Page 48872]]
must meet increased local demand.\193\ Alaska's Fairbanks
PM2.5 nonattainment plan restricts the fuel oil sulfur
content for residents and business to less than 1,000 ppm.\194\ As a
result of this requirement, these customers have consumed the majority
of the available supply of No. 1 fuel oil in the area.\195\
---------------------------------------------------------------------------
\192\ See October 6, 2025, clarification letter in the docket
for this action, enclosure at page 11.
\193\ Id. Enclosure at page 9.
\194\ 18 AAC 50.078; 40 CFR 52.70(c).
\195\ See October 6, 2025, clarification letter in the docket
for this action, enclosure at page 9.
---------------------------------------------------------------------------
Alaska also confirmed its prior analysis that requiring USLD at EU
5 would have a cost effectiveness of over $1 million.\196\ Alaska thus
determined that no controls are necessary on EUs 5 or 6 in the second
planning period.
---------------------------------------------------------------------------
\196\ Id. Enclosure at pages 11 and 12.
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Therefore, based on the updated BACT analysis and updated fuel cost
data, the State determined that no SO2 controls were
necessary for reasonable progress in the second implementation period
at the North Pole Power Plant.
iii. EPA Evaluation
As previously stated, relying on recent SO2 BACT
analyses to also satisfy regional haze requirements is appropriate and
consistent with the EPA 2019 Guidance.\197\ We concur with the State's
finding that no SO2 controls are necessary for reasonable
progress, based on Alaska's reasonable evaluation of the four statutory
factors. Alaska derived the cost of firing lower sulfur fuels based on
two primary factors: (1) the cost of building fuel oil storage; and (2)
the variability in fuel prices.\198\ Currently, there is no local low
sulfur fuel oil refining in Fairbanks. Petro Star supplies fuel oil to
the region, but its facility lacks desulfurization capabilities. Thus,
requiring sources in Fairbanks to fire lower sulfur fuel necessarily
means transporting that fuel by truck or rail from southern Alaska. The
Alaska DEC pointed out the costs and logistical challenges of doing so.
Given these challenges, building out large volume storage in Fairbanks
would be necessary to comply with any lower sulfur fuel requirements,
e.g. ULSD. In its 2024 SIP submission for the Fairbanks
PM2.5 nonattainment area, Alaska estimated that the cost of
switching to ULSD was approximately $13,838 per ton for EU 1, $13,923
per ton for EU 2, and $1,040,822 per ton for EUs 5 and 6.\199\ Alaska's
most recent cost estimates indicate that the cost of switching to USLD
across each of these units is even higher. Thus, Alaska evaluated the
cost, energy and non-air quality impacts of building fuel oil storage
in Fairbanks, as well as the time needed to construct the storage tanks
and their remaining useful life.\200\
---------------------------------------------------------------------------
\197\ EPA 2019 Guidance at page 23.
\198\ State Air Quality Control Plan, Vol. II, Section
III.D.7.7.13.8.5.3 at https://www.regulations.gov/document/EPA-R10-OAR-2024-0595-0027 or see file
128_State_Submission_Fairbanks_Control_Strategies_11_5_2024.pdf at
pages 75-76 in the docket for this action.
\199\ Ibid.
\200\ Ibid.
---------------------------------------------------------------------------
Recent developments impacting the cost and availability of Alaska
No. 1 fuel oil make firing lower sulfur fuel oil in EUs 1 and 2
impractical and cost prohibitive. The Fairbanks PM2.5
nonattainment plan requires home heating oil to meet lower sulfur
content requirements, and this control measure has restricted the
availability of No. 1 fuel oil for industrial use and caused further
variability in fuel oil prices in interior Alaska.\201\ Therefore, the
State's finding, that current fuel prices suggest a fuel switch to No.
1 fuel oil in EUs 1 and 2 would be cost prohibitive for the regional
haze second implementation period, also appears reasonable.
---------------------------------------------------------------------------
\201\ State Air Quality Control Plan, Appendix III.D.7.7 in EPA
docket EPA-R10-OAR-2024-0595 or see file
129_State_Submission_Fairbanks_Control_Strategies_Appendix_11_5_2024.
pdf at pages 76-84 in the docket for this action.
---------------------------------------------------------------------------
With respect to EUs 5 and 6, we concur with the State's finding
that no SO2 controls are necessary for reasonable progress,
based on Alaska's reasonable evaluation of the four statutory
factors.\202\ The EPA previously reviewed Alaska's determination--that
continued use of light straight run constituted SO2 BACT--as
part of its review of the Fairbanks PM2.5 nonattainment area
plan. This analysis, as well as the analysis in the Alaska regional
haze plan, supports the finding that no additional controls are cost
effective. Additionally, because light straight run is the normal
operating fuel for EUs 5 and 6 and GVEA is under long-term contract to
purchase light straight run from Petro Star via direct pipeline, it is
reasonable to assume the long-standing, current requirement to fire
light straight run (50 ppmw) year-round, except during startup (Jet-A,
300 ppmw), is unlikely to change.\203\
---------------------------------------------------------------------------
\202\ The documentation for this finding can be found in State
Air Quality Control Plan, Vol. II, Appendix III.D.7.7-301-307 at
https://www.regulations.gov/document/EPA-R10-OAR-2024-0595-0078 or
see file 127_State_Submission_BACT_Analysis_11_5_2024.pdf at pages
301-307 in the docket for this action.
\203\
130_State_Submission_North_Pole_Power_Plant_Fuel_Information.xlsx in
the docket for this action. Note this information was submitted as
part of the Fairbanks PM2.5 nonattainment plan and may
also be found in EPA docket EPA-R10-OAR-2020-0060.
---------------------------------------------------------------------------
4. Additional Long-Term Strategy Requirements
The consultation requirements of 40 CFR 51.308(f)(2)(ii) provide
that States must consult with other States that are reasonably
anticipated to contribute to visibility impairment in a Class I area to
develop coordinated emission management strategies containing the
emission reductions measures that are necessary to make reasonable
progress. Section 51.308(f)(2)(ii)(A) and (B) require States to
consider the emission reduction measures identified by other States as
necessary for reasonable progress and to include agreed upon measures
in their SIPs, respectively. Section 51.308(f)(2)(ii)(C) speaks to what
happens if States cannot agree on what measures are necessary to make
reasonable progress.
Alaska participated in and provided documentation of the WRAP
intra- and inter-regional planning organization consultation processes
in the submission.\204\ Alaska has not identified any other State that
is impacting Alaska's Class I areas, and Alaska has not been identified
as a contributor to impacts in other States' Class I areas.\205\ To
address 40 CFR 51.308(f)(2)(ii)(A), (B), and (C), the Alaska DEC
participated in the WRAP-facilitated process during which no
disagreements were raised by other States with respect to Alaska's
planning efforts for the regional haze second implementation period.
Considering these facts, we agree that Alaska has adequately satisfied
the consultation requirements of 40 CFR 51.308(f)(2)(ii).
---------------------------------------------------------------------------
\204\ Alaska submission, Combined Section III.K.13, Section
III.K.13.K. State, Tribe, and Federal Land Manager Consultation.
\205\ Id. Page III.K.13.K-3.
---------------------------------------------------------------------------
The documentation requirement of 40 CFR 51.308(f)(2)(iii) provides
that States may meet their obligations to document the technical bases
on which they are relying to determine the emission reduction measures
that are necessary to make reasonable progress through a regional
planning organization, as long as the process has been ``approved by
all State participants.'' As explained previously, Alaska relied on
WRAP technical information, modeling, and analysis to support
development of its long-term strategy as described in the
submission.\206\ Alaska built on the WRAP technical tools and
contracted out additional modeling for purposes of the submission.\207\
---------------------------------------------------------------------------
\206\ Id. Section III.K.13.G.
\207\ Ibid.
---------------------------------------------------------------------------
Section 51.308(f)(2)(iii) also requires that the emissions
information considered to determine the measures
[[Page 48873]]
that are necessary to make reasonable progress include information on
emissions for the most recent year for which the State has submitted
triennial emissions data to the EPA (or a more recent year), with a 12-
month exemption period for newly submitted data.
The 2017 National Emissions Inventory is considered a
representative recent triennial inventory and therefore, the EPA has
included in the docket for this action the 2017 National Emissions
Inventory data for Alaska.\208\ Based on the documentation provided by
Alaska and the EPA's supplemental inventory data, we agree that Alaska
has adequately satisfied the requirements of 40 CFR 51.308(f)(2)(iii).
---------------------------------------------------------------------------
\208\ See Excel spreadsheet of EPA National Emissions Inventory
NOX and SO2 data trends for Alaska in the
docket for this action.
---------------------------------------------------------------------------
5. Five Additional Factors
In developing its long-term strategy, a State must also consider
five additional factors set forth at 40 CFR 51.308(f)(2)(iv). The
factors are: (1) Emission reductions due to ongoing air pollution
control programs, including measures to address reasonably attributable
visibility impairment; (2) Measures to mitigate the impacts of
construction activities; (3) Source retirement and replacement
schedules; (4) Smoke management practices for agricultural and forestry
burning; and (5) Anticipated net effect on visibility over the period
of the long-term strategy. The following paragraphs address each of the
five additional factors.
a. Emissions Reductions Due to Ongoing Programs
Alaska implements ongoing programs and regulations that protect
visibility. Historically, there were specific vistas established as
special protection areas in State regulation, including Mt. Deborah and
the Alaska Range East, as viewed from approximately the Savage River
Campground area, and Denali, Alaska Range, and the Interior Lowlands,
as viewed from the vicinity of Wonder Lake, in addition to the Alaska
Class I areas.\209\ Additionally, Alaska implements a SIP-approved new
source review program for both major and minor stationary sources as
laid out in Articles 3 and 5 of 18 AAC 50, respectively. Importantly,
Federal diesel fuel regulations limit the sulfur content of fuel \210\
including fuel powering commercial marine vessels.\211\
---------------------------------------------------------------------------
\209\ 18 AAC 50.025 Visibility and Special Protection Areas.
\210\ See https://www.epa.gov/diesel-fuel-standards.
\211\ Fuel sulfur limits are codified at 40 CFR part 1043. See
84 FR 69335, December 18, 2019, at page 69336.
---------------------------------------------------------------------------
The State has implemented a comprehensive PM2.5 control
program for the Fairbanks nonattainment area, which includes
controlling pollutants from residential wood heaters, power plants and
other sources in the area.\212\ In addition, the submission pointed to
Federal mobile source regulations that apply nationwide and that are
expected to reduce haze-forming pollutants over time as requirements
phase in and fleets turn over.\213\
---------------------------------------------------------------------------
\212\ Alaska submission, Combined Section III.K.13, Page
III.K.13.H-10.
\213\ Id., Page III.K.13.H-9.
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b. Measures To Mitigate the Impacts of Construction Activities
Alaska's SIP includes measures to mitigate the impacts of
construction activities, such as standards to reduce fugitive dust
emissions from construction \214\ and dust management plans for new
construction permitting.\215\ The submission stated that the Alaska DEC
also reviews and comments on draft environmental impact statements for
required dust mitigation plans.\216\
---------------------------------------------------------------------------
\214\ 18 AAC 50.045(d).
\215\ Alaska submission, Combined Section III.K.13, Page
III.K.13.H-28.
\216\ Ibid.
---------------------------------------------------------------------------
c. Source Retirement and Replacement Schedules
Source retirements and replacements were considered throughout the
Alaska submission. The Alaska submission stated that the Harvest
Alaska, LLC Drift River Platform/Christy Lee Platform was
decommissioned as of October 2019.\217\ The Alaska DEC issued a
Rescission Request Approval Letter for the source's title V Operating
Permit AQ0190TVP03 Revision 1 on December 12, 2019. Additionally, the
Alaska submission stated that the U.S. Air Force decommissioned the
three 177 MMBtu/hr coal-fired boilers that made up the Clear Space
Force Station Combined Heat and Power Plant, located approximately 12
km from Denali National Park.\218\ The old boilers were retired in
2016, and the Clear Space Force Station is now connected to the local
GVEA power grid. The source emitted 213 tons sulfur dioxide in 2014 and
after the shutdown, emitted less than 0.1 tons sulfur dioxide in
2019.\219\ Finally, in 2019, the University of Alaska Fairbanks
replaced the Campus Power Plant's aging coal-fired boilers with a new
coal-fired boiler equipped with an integrated fluidized bed limestone
injection system to control SO2 emissions. Estimated
SO2 emissions fell from 163.8 tpy in 2017 to 20.6 tpy in
2020.\220\
---------------------------------------------------------------------------
\217\ Id., Appendix III.K.13.F-12.
\218\ Id. Appendix III.K.13.F-10.
\219\ Ibid.
\220\ Based on 2017 and 2020 National Emissions Inventory data.
---------------------------------------------------------------------------
d. Smoke Management Practices
Alaska addressed smoke management in the submission by citing the
State's enhanced smoke management practices for agricultural and
forestry burning.\221\ The enhanced smoke management plan outlines the
process, practices, and procedures to manage smoke from prescribed and
other open burning. The plan was most recently updated on December 1,
2021.\222\ In addition, Alaska's SIP-approved open burning regulations
are found at 18 AAC 50.065. The open burning rules address types of
open burning within the State and, among other things, limit the
materials that may be burned, prescribe how a burn must be conducted,
limit smoldering, and prohibit black smoke.
---------------------------------------------------------------------------
\221\ Alaska submission, Combined Section III.K.13, Page
III.K.13.H-28 through H-31.
\222\ Id., Page III.K.13.H-30.
---------------------------------------------------------------------------
e. Anticipated Net Effect on Visibility
In the submission, Alaska considered the anticipated net effect of
projected changes in emissions by discussing the photochemical modeling
for the 2018 through 2028 period it conducted in collaboration with the
WRAP, the EPA, and the University of Alaska Fairbanks.\223\ Emissions
inventories in the Alaska submission indicated that anthropogenic
SO2 emissions in Alaska were anticipated to decline
significantly through 2028, primarily due to Federal regulation of
sulfur in fuel.\224\ The submission stated that the overall visibility
benefits of these reductions are expected to be offset to some degree
by natural sources of SO2, including wildfires, and the
continued transport of international anthropogenic emissions from Asia
across the Pacific Ocean.\225\
---------------------------------------------------------------------------
\223\ Id., Section III.K.13.G.
\224\ Id., Section III.K.13.E.
\225\ Id., Page III.K.13.H-31.
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[[Page 48874]]
We find that Alaska has reasonably considered each of the five
additional factors and has adequately satisfied the requirements of 40
CFR 51.308(f)(2)(iv).
6. Conclusion
As described in the preceding paragraphs, the EPA proposes to
approve the Alaska submission as meeting the long-term strategy
requirements of 40 CFR 51.308(f)(2).
F. Reasonable Progress Goals
Section 51.308(f)(3) contains the requirements pertaining to
reasonable progress goals for each Class I area. Because Alaska is host
to Class I areas, it is subject to both 40 CFR 51.308(f)(3)(i), and
potentially, to (ii). Section 51.308(f)(3)(i) requires a State in which
a Class I area is located to establish reasonable progress goals--one
each for the most impaired and clearest days--reflecting the visibility
conditions that will be achieved at the end of the implementation
period as a result of the emission limitations, compliance schedules
and other measures required under 40 CFR 51.308(f)(2) to be in States'
long-term strategies, as well as implementation of other CAA
requirements. The long-term strategies as reflected by the reasonable
progress goals must provide for an improvement in visibility on the
most impaired days relative to the baseline period and ensure no
degradation on the clearest days relative to the baseline period.
Section 51.308(f)(3)(ii) applies in circumstances in which a Class
I area's reasonable progress goals for the most impaired days
represents a slower rate of visibility improvement than the uniform
rate of progress calculated under 40 CFR 51.308(f)(1)(vi). Under 40 CFR
51.308 51.308(f)(3)(ii)(A), if the State in which a Class I area is
located establishes a reasonable progress goal for the most impaired
days that provides for a slower rate of visibility improvement than the
uniform rate of progress, the State must demonstrate that there are no
additional emission reduction measures for anthropogenic sources or
groups of sources in the State that would be reasonable to include in
its long-term strategy.
Section 51.308(f)(3)(ii)(B) requires that if a State contains
sources that are reasonably anticipated to contribute to visibility
impairment in a Class I area in another State, and the reasonable
progress goal for the most impaired days in that Class I area is above
the uniform rate of progress, the upwind State must provide the same
demonstration.
1. Adjusted Uniform Rate of Progress
To address 40 CFR 51.308(f)(3)(i), the Alaska submission stated
that visibility on the 20% clearest days at all Class I areas in Alaska
is projected to be below the baseline visibility condition satisfying
the Regional Haze Rule requirement of no degradation in visibility for
the clearest days since the baseline period.\226\ For the most impaired
days, Alaska compared the 2028 RPGs to the EPA-adjusted uniform rate of
progress (URP) for 2028. To arrive at the EPA-adjusted URP, the EPA
conducting photochemical grid modeling using the CMAQ modeling
platform, taking into account certain international anthropogenic
sulfate emissions.\227\ The EPA's modeling made use of 2016 emissions
inventory data to represent emissions for the current visibility period
and projected the data to 2028 to represent emissions for the end of
the second planning period. The projection was based on predicted
economic growth, population expansion or contraction, and other
factors.\228\ The EPA's adjustments yielded a relatively flat URP.\229\
The EPA also ran a 2028 zero-out U.S. anthropogenic emissions CMAQ
modeling scenario. This zero-out U.S. model run indicated that even
when all U.S. anthropogenic emissions were eliminated from the model,
Alaska Class I areas saw essentially no visibility benefit.\230\ This
EPA zero-out U.S. model run provides additional support for the State's
conclusion that no retrofit controls are necessary for reasonable
progress in the second implementation period.
---------------------------------------------------------------------------
\226\ Id., Figure II.K.13.I-1.
\227\ Technical Support Document for the EPA's Updated 2028
Regional Haze Modeling for Hawaii, Virgin Islands, and Alaska. EPA-
454/R-21-007. August 2021.
\228\ Ibid.
\229\ Alaska submission, Combined Section III.K.13, Figure
III.K.13.I-2.
\230\ Technical Support Document for the EPA's Updated 2028
Regional Haze Modeling for Hawaii, Virgin Islands, and Alaska. EPA-
454/R-21-007. August 2021.
---------------------------------------------------------------------------
To further investigate the role of international and natural
emissions, Alaska conducted a supplemental modeling analysis that
screened out days with measured high ammonium sulfate, under the
assumption that high sulfate is a proxy for volcanic emissions impacts
at the monitor, similar to the screening for wildfire contributions
using carbon and crustal measurements as proxies.\231\ Alaska used this
screened data to develop alternative URPs and RPGs on the most impaired
days. Alaska stated in the submission that this process was done to
attempt to account for volcanic-caused sulfate and resulted in 2028
RPGs below the URP for 2028.\232\
---------------------------------------------------------------------------
\231\ Alaska submission, Combined Section III.K.13, Page
III.K.13.I-8.
\232\ Id., Appendix III.K.13.I.
\233\ Source: Alaska submission, Combined Section III.K.13,
Table III.K.13.I-1.
---------------------------------------------------------------------------
Tables 7 and 8 of this document compare the baseline, 2028
projected RPG, adjusted URP for 2028, and 2028 zero-out U.S. scenario
for each Class I area.
Table 7--Clearest Days 2028 Projected Reasonable Progress Goal (RPG)
Compared to EPA-Adjusted Uniform Rate of Progress (URP) for 2028 in
Deciviews \233\
------------------------------------------------------------------------
2028 Projected
IMPROVE station Baseline RPG
------------------------------------------------------------------------
DENA1............................. 2.43 2.16
TUXE1............................. 3.99 3.79
SIME1............................. 7.90 7.56
------------------------------------------------------------------------
Table 8--Most Impaired Days 2028 Projected Reasonable Progress Goal (RPG) Compared to EPA and Alaska-Adjusted Uniform Rate of Progress (URP) for 2028 in
Deciviews \234\
--------------------------------------------------------------------------------------------------------------------------------------------------------
2028 Projected 2028 EPA zero- 2028 Un- 2028 EPA- 2028 Alaska-
IMPROVE station Baseline RPG out U.S. adjusted URP adjusted URP adjusted URP
--------------------------------------------------------------------------------------------------------------------------------------------------------
DENA1................................................... 7.08 6.53 6.41 6.14 6.46 6.92
[[Page 48875]]
TUXE1................................................... 10.47 10.66 10.01 9.07 10.25 10.37
SIME1................................................... 13.67 13.57 14.05 11.60 13.35 13.04
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 7 of this document appears to indicate that the projected
2028 RPGs on the clearest days are below the baseline. Table 8 appears
to show that projected 2028 RPGs on the most impaired days are within
half of a deciview of the EPA and Alaska adjusted URPs for 2028. We
note that when all U.S. anthropogenic emissions were eliminated from
the EPA CMAQ modeling (EPA zero-out U.S. for 2028), DENA1 and TUXE1 saw
little to no visibility benefit and SIME1 saw a modeled visibility
degradation.\235\ Alaska included data and modeling in the submission
to support the State's assertion that this unusual zero-out modeling
result may be explained by unaccounted for natural haze pollutant
sources, international emissions contributions, uncertainties with
model inputs, and model performance issues, among other factors.\236\
---------------------------------------------------------------------------
\234\ Sources: Alaska submission, Combined Section III.K.13,
Table III.K.13.I-2.
\235\ Ibid.
\236\ See Alaska submission, Combined Section III.K.13, Section
III.K.13.I. Reasonable Progress Goals.
---------------------------------------------------------------------------
2. URP Glidepath Check
The EPA proposes to find that Alaska's Regional Haze Plan satisfies
the requirements in 40 CFR 51.308(f)(3)(ii). While Alaska's 2028 RPG
appears to provide for a slower rate of improvement in visibility than
the URP, in accordance with 40 CFR 51.308(f)(3)(ii)(A), Alaska: (1)
demonstrated that there are no additional emission reduction measures
that would be reasonable to include in its long-term strategy; and (2)
provided a robust demonstration, including documenting the criteria
used to determine which sources or groups of sources were evaluated,
detailing how the four factors were taken into consideration in
selecting the measures for inclusion in its long-term strategy.
With respect to the Tuxedni and Simeonof Wilderness Areas, Alaska
determined that there were no significant anthropogenic sources
contributing to visibility in those areas. The State used a
conservative Q/d >1.0 threshold for selecting sources. Even with this
very low threshold, no sources had a Q/d of >1.0. Alaska verified that
the sources potentially impacted these Class I Areas have very low
actual emissions. See section IV.E. of this document for more details.
With respect to Denali National Park all sources except for the
Healy Power Plant are located over 100 km away from the Park. For the
three sources located within the Fairbanks PM2.5
nonattainment area, Alaska relied upon extensive SO2
nonattainment BACT analyses to demonstrate its consideration of the
four statutory factors for regional haze. For Eielson Air Force Base
and Healy Power Plant, the State determined through consideration of
the four factors that the largest emission units were already well
controlled.
Moreover, Alaska included evidence indicating that additional
SO2 controls at these sources are unlikely to improve
visibility in Denali National Park. Specifically, natural sulfate
contributions may not be properly accounted for in the EPA's CMAQ
modeling which adds uncertainty to the results of the visibility
modeling in Alaska, and emissions inventory information that supports
the argument that much of the sulfate contributions to the IMPROVE
monitors in Alaska are from source categories outside the State's
control (emissions transported from Asia, commercial marine shipping
emissions, wildfire emissions, sea salt and oceanic dimethyl sulfide).
Therefore, the EPA finds that no additional requirements apply under 40
CFR 51.308(f)(3)(ii)(A).
Under 40 CFR 51.308(f)(3)(ii)(B), a State that contains sources
that are reasonably anticipated to contribute to visibility impairment
in a Class I area in another State for which a demonstration by the
other State is required under 40 CFR 51.308(f)(3)(ii)(B) must
demonstrate that there are no additional emission reduction measures
that would be reasonable to include in its long-term strategy. Alaska
has not identified any other State that is impacting Alaska's Class I
areas, and no other State has identified Alaska as a contributor to
impacts in other States' Class I areas. Therefore, 40 CFR
51.308(f)(2)(ii)(B) and (C) do not apply to Alaska.
As noted in the RHR at 40 CFR 51.308(f)(3)(iii), the RPGs are not
directly enforceable but will be considered by the Administrator in
evaluating the adequacy of the measures in the implementation plan in
providing for reasonable progress towards achieving natural visibility
conditions at that area. As discussed in the preceding paragraphs, we
are proposing to approve the Alaska submission for purposes of the
long-term strategy control requirements in 40 CFR 51.308(f)(2).
Compliance with the RPGs is dependent on compliance with the long-term
strategy. Because the RPGs reflect the visibility conditions that are
projected to be achieved by the end of the second implementation period
as a result of the long-term strategy, we are proposing to approve the
submission for the applicable requirements of 40 CFR 51.308(f)(3)
relating to reasonable progress goals for Alaska Class I areas.
G. Monitoring Strategy and Other Implementation Plan Requirements
Section 51.308(f)(4) requires that if the EPA or the affected FLM
has advised a State of a need for additional monitoring to assess
reasonably attributable visibility impairment at the mandatory Class I
area in addition to the monitoring currently being conducted, the State
must include in the plan revision an appropriate strategy for
evaluating reasonably attributable visibility impairment in the
mandatory Class I area by visual observation or other appropriate
monitoring techniques. The EPA and the FLMs have not advised Alaska
that additional monitoring is needed to assess reasonably attributable
visibility impairment. Therefore, the requirements under 40 CFR
51.308(f)(4) are not applicable. Accordingly, the EPA proposes to
approve the portions of the Alaska submission relating to 40 CFR
51.308(f)(4).
Section 51.308(f)(6) specifies that each comprehensive revision of
a State's regional haze SIP must contain or provide for certain
elements, including monitoring strategies, emissions inventories, and
any reporting, recordkeeping and other measures needed to assess and
report on
[[Page 48876]]
visibility. A main requirement of this subsection is for States with
Class I areas to submit monitoring strategies for measuring,
characterizing, and reporting on visibility impairment. Compliance with
this requirement may be met through participation in the IMPROVE
network.
The Alaska submission highlighted the significant challenge of
monitoring visibility at extremely remote Class I areas.\237\ Reliable
power is a concern, in addition to problems with site access and
equipment maintenance. Most notably, the Bering Sea Wilderness Area is
so remote that visibility monitoring could not be established, making
it the only Class I area in the U.S. without an IMPROVE monitor.\238\
Despite these challenges, the IMPROVE network in Alaska continues to
provide representative data from three IMPROVE monitors, DENA1, SIME1,
and KPBO1.
---------------------------------------------------------------------------
\237\ Id., Page III.K.13.C-4.
\238\ See https://vista.cira.colostate.edu/Improve/improve-program/.
---------------------------------------------------------------------------
We note that Alaska also operates a protocol site at Trapper Creek
near Denali National Park (TRCR1).\239\ The submission stated that
Alaska established this protocol site to evaluate the long-range
transport of pollution into the park from more densely populated and
industrialized areas to the south.\240\ Data from protocol sites may be
compared to data from IMPROVE stations, however, protocol sites are not
considered representative of visibility in Class I areas.\241\ National
Park Service comments submitted on the draft submission and the Alaska
DEC responses to those comments make clear that DENA1 is the
representative IMPROVE station for Denali National Park, while TRCR1
remains a protocol site.\242\
---------------------------------------------------------------------------
\239\ Alaska submission, Combined Section III.K.13, Figures
III.K.D-2, D-6, D-10, D-14.
\240\ Ibid.
\241\ See IMPROVE website at https://vista.cira.colostate.edu/Improve/.
\242\ Alaska submission, Combined Section III.K.13, Pages
III.K.C-1 and C-2.
---------------------------------------------------------------------------
We propose to find that the visibility monitoring network in Alaska
is appropriate for the unique logistical challenges and extremely
remote locations of the Class I areas in the State. The network is
designed as well as possible to ensure the air monitoring data
collected is representative of the air quality within the Alaska Class
I areas.
Section 51.308(f)(6)(i) requires SIPs to provide for the
establishment of any additional monitoring sites or equipment needed to
assess whether reasonable progress goals to address regional haze for
all Class I areas within the State are being achieved.
As listed in Table 1 of this document, according to Alaska,
visibility data for Alaska's Class I areas are collected at IMPROVE
stations currently operated by the National Park Service at Denali
National Park Headquarters (DENA1) and the U.S. Fish and Wildlife
Service in Sandpoint (SIME1) and the Kenai Peninsula Borough south of
Ninilchik (KPBO1). The Alaska DEC also operates the protocol site at
Trapper Creek (TRCR1). In addition, several other monitoring networks
have sites at the Denali National Park Headquarters. These include the
Clean Air Status and Trends Network (CASTNET) monitor, the National
Atmospheric Deposition Program, and the National Park Service's
meteorological monitoring equipment.\243\ Therefore, the EPA finds that
Alaska has adequately satisfied 40 CFR 51.308(f)(6)(i).
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\243\ Ibid.
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Section 51.308(f)(6)(ii) requires SIPs to provide for procedures by
which monitoring data and other information are used in determining the
contribution of emissions from within the State to regional haze
visibility impairment at Class I areas both within and outside the
State.
Alaska relied on WRAP emissions inventory and technical tools, EPA
modeling, and modeling conducted by the University of Alaska Fairbanks
to assess the impact of emissions from within the State on Class I
areas in the State. The tools and analyses included the EPA's three-
dimensional grid-based Eulerian air quality model (CMAQ), a global 3-D
chemical transport model (GEOS-CHEM), as well as a variety of data
analysis techniques that include back trajectory calculations, area of
influence and weighted emissions potential analysis, and the use of
monitoring and inventory data. Therefore, we find that Alaska has
adequately satisfied the requirements of 40 CFR 51.308(f)(6)(ii).
We note that 40 CFR 51.308(f)(6)(iii) does not apply to Alaska
because it has Class I areas. Section 51.308(f)(6)(iv) requires the SIP
to provide for the reporting of all visibility monitoring data to the
Administrator at least annually for each Class I area in the State. To
satisfy 40 CFR 51.308(f)(6)(iv), the Alaska regional haze plan states
that Alaska complies with this requirement by participating in the
IMPROVE program.\244\ IMPROVE filters are collected routinely every
third day. The IMPROVE sampler consists of four independent modules,
each of which incorporates a separate inlet, filter pack, and pump
assembly. Modules A, B, and C are equipped with 25 mm diameter filters
and 2.5 [mu]m cyclones that allow for sampling of particles with
aerodynamic diameters less than 2.5 [mu]m (PM2.5). Module D
is fitted with a PM10 inlet to collect particles with
aerodynamic diameters less than 10 [mu]m. Each module contains a filter
substrate specific to the planned chemical analysis. All analytical
results are compiled by the laboratory responsible for network
operations and for initial processing and validation. Data are
delivered to the Environmental Protection Agency (EPA) Air Quality
System database and to the Cooperative Institute for Research in the
Atmosphere (CIRA) Federal Land Manager Environmental Database
(FED).\245\
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\244\ See https://vista.cira.colostate.edu/Improve/data-acknowledgment/. IMPROVE is a collaborative association of State,
Tribal, and Federal agencies, and international partners. The EPA is
the primary funding source, with contracting and research support
from the National Park Service. The Air Quality Research Center at
the University of California, Davis is the central analytical
laboratory, with ion analysis provided by Research Triangle
Institute, and carbon analysis provided by Desert Research
Institute.
\245\ See https://vista.cira.colostate.edu/Improve/wp-content/uploads/2023/10/IMPROVE_Data_User_Guide_24October2023.pdf/.
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Section 51.308(f)(6)(v) requires SIPs to provide for a Statewide
inventory of emissions of pollutants that are reasonably anticipated to
cause or contribute to visibility impairment, including emissions for
the most recent year for which data are available and estimates of
future projected emissions. It also requires a commitment to update the
inventory periodically.
The Alaska submission relied on a 2016 inventory to represent
emissions for the current visibility period (2014-2018) and a future
forecast 2028 inventory to represent the end of the second planning
period. Alaska put together the 2028 inventory using a 2016 base
dataset adjusted to predict emissions in 2028 based on economic growth,
population expansion or contraction, and other factors.\246\
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\246\ Alaska submission, Combined Section III.K.13, Section
III.K.III.E. Emission Inventory.
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Alaska broke down pollution inventories in the 2016 inventory by
source category and air pollutant, including volatile organic compounds
(VOCs), carbon monoxide (CO), nitrogen oxides (NOX), sulfur
oxides (SOX), ammonia (NH3), and particulate
matter (PM10 and PM2.5).\247\ The inventories
represented sources and source categories Statewide including
[[Page 48877]]
stationary point and areas sources, fugitive dust, anthropogenic and
natural fires, and on-road and non-road mobile sources. The EPA used
these inventories to complete modeling for Alaska using the CMAQ
modeling platform. See section IV.F. of this document for more
information on the EPA's CMAQ modeling for Alaska.
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\247\ Carbon monoxide is not considered a haze pollutant, but
was included in the datasets because it is one of the criteria
pollutants.
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The Alaska submission noted that Alaska reviewed the raw inventory
data, focusing in part on maritime emissions. The maritime industry
operates throughout the State and provides critical transportation
services to communities.\248\ There is also a major international
shipping lane through the Gulf of Alaska. In general, marine sector
emissions are understood to contribute to sulfate and potential
visibility impairment at coastal Class I areas. For future forecasting
purposes, the EPA's modeling used 2016 emissions as the 2028 baseline
and adjusted for emissions reductions predicted by Federal and
international sulfur content limits on commercial marine fuel.\249\
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\248\ Alaska submission, Combined Section III.K.13, Page
III.K.13.E-4 and E-5.
\249\ The International Marine Organization (IMO) established
emission standards for vessels operating in designated waters off
the coast of North America. MARPOL Annex VI is codified at 33 U.S.C.
1901 et seq. Pursuant to 33 U.S.C. 1907 it is unlawful to act in
violation of the MARPOL Protocol. The North American Emissions
Control Area (ECA) covers most coastal areas of the United States,
including southeast Alaska and the Gulf of Alaska. Vessels operating
in the area must burn low sulfur marine fuel, 1,000 ppm sulfur
content (0.10% sulfur by weight). As of January 1, 2020, the IMO
limited sulfur in fuel for ships operating outside designated ECAs
to 5,000 ppm sulfur content (0.50% sulfur by weight. Fuel sulfur
limits are codified at 40 CFR part 1043. See 84 FR 69335, 69336
(December 18, 2019). This limit represents a substantial reduction
from the prior IMO limit of 35,000 ppm sulfur content (3.5% sulfur
by weight).
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The Alaska submission included tables that illustrated Statewide
annual emissions (in tons/year) by source sector and pollutant for the
2016 and projected 2028 inventories and also included anthropogenic
emissions fractions.\250\ We have summarized the emissions data in
Tables 9 and 10 of this document.
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\250\ Alaska submission, Combined Section III.K.13, Tables
III.K.13.E-1 and III.K.13.E-2 and Figures III.K.13.E-2 and
III.K.13.E-3.
Table 9--2016 Alaska Emissions Inventory Summary
[Tons per year]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sector VOC CO NOX PM2.5 SO2 NH3
--------------------------------------------------------------------------------------------------------------------------------------------------------
Agriculture............................................. 9 .............. .............. .............. .............. 109
Airports................................................ 2,008 13,478 4,417 271 576 ..............
Rail.................................................... 17 48 386 11 0 0
Commercial Marine Vessel C1/C2.......................... 216 956 6,317 160 11 3
Commercial Marine Vessel C3............................. 1,998 4,310 46,238 3,123 23,736 60
Non-road................................................ 8,600 34,126 2,580 358 7 6
On-road................................................. 8,228 60,101 11,977 489 33 153
Non-point............................................... 8,224 28,956 6,307 2,500 1,510 564
Residential Wood Combustion............................. 820 5,073 90 712 16 34
Fugitive Dust........................................... .............. .............. .............. 1,054 .............. ..............
Oil and Gas............................................. 26,974 13,128 42,779 540 1,702 0
Electric Generating Units............................... 307 2,445 7,793 240 1,304 2
Other Points............................................ 800 2,562 7,291 478 1,394 48
Fires................................................... 743,060 3,165,511 29,644 262,648 19,646 51,691
-----------------------------------------------------------------------------------------------
Total............................................... 801,260 3,330,692 165,819 272,583 49,935 52,670
--------------------------------------------------------------------------------------------------------------------------------------------------------
Anthropogenic Fraction.................................. 7% 5% 82% 4% 61% 2%
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 10--2028 Alaska Emissions Inventory Summary
[Tons per year]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sector VOC CO NOX PM2.5 SO2 NH3
--------------------------------------------------------------------------------------------------------------------------------------------------------
Agriculture............................................. 10 .............. .............. .............. .............. 119
Airports................................................ 1,945 14,915 4,371 257 598 ..............
Rail.................................................... 18 48 391 11 0 0
Small Commercial Marine Vessel (C1/C2).................. 114 958 3,500 91 4 2
Large Commercial Marine Vessel C3....................... 2,836 6118 59,990 2,430 7.080 47
Non-road................................................ 5,297 30,035 1,722 201 4 7
On-road................................................. 4,142 30,961 4,789 217 23 136
Non-point............................................... 8,043 29,242 6,725 2,518 1,524 650
Residential Wood Combustion............................. 759 4,731 93 647 13 30
Fugitive Dust........................................... .............. .............. .............. 1,063 .............. ..............
Oil and Gas............................................. 26,606 13,101 42,703 537 1,697 0
Electric Generating Units............................... 307 2,445 7,793 240 1,304 2
Other Points............................................ 736 2,559 7,269 483 1,404 48
Fires................................................... 743,060 3,165,511 29,644 262,648 19,646 51,691
-----------------------------------------------------------------------------------------------
Total............................................... 793,874 3,300,624 168,989 271,342 33,296 52,732
--------------------------------------------------------------------------------------------------------------------------------------------------------
Anthropogenic Fraction.................................. 6% 4% 82% 3% 41% 2%
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 48878]]
In reviewing these inventories, Alaska noted that fire emissions
are several orders of magnitude larger than emissions from other source
sectors. Alaska stated that fire emissions appeared steady from 2016 to
the 2028 projection, however, there was significant variability from
year to year. Regarding individual pollutants, according to Alaska, the
most notable change was an estimated 30% decrease in anthropogenic
SO2 emissions from all sources from 2016 to the 2028
projection. Based on Alaska's consideration and analysis of emissions
data in the submission, the EPA proposes to find that Alaska has
satisfied the emissions information requirement in 40 CFR
51.308(f)(6)(v).
In sum, the EPA proposes to approve Alaska's submission as meeting
the requirements of 40 CFR 51.308(f)(6), as described in section IV.G.
of this document, including through the State's continued participation
in the IMPROVE network and the WRAP and the State's on-going compliance
with the Air Emissions Reporting Rule, and that no further elements are
necessary at this time for Alaska to assess and report on visibility
pursuant to 40 CFR 51.308(f)(6)(vi).
H. Requirements for Periodic Reports Describing Progress Towards the
Reasonable Progress Goals
Section 51.308(f)(5) requires that periodic comprehensive revisions
of States' regional haze plans also address the progress report
requirements of 40 CFR 51.308(g)(1) through (5). The purpose of these
requirements is to evaluate progress towards the applicable reasonable
progress goals for each Class I area within the State and each Class I
area outside the State that may be affected by emissions from within
that State. Sections 51.308(g)(1) and (2) apply to all States and
require a description of the status of implementation of all measures
included in a State's first implementation period regional haze plan
and a summary of the emission reductions achieved through
implementation of those measures. Section 51.308(g)(3) applies only to
States with Class I areas within their borders and requires such States
to assess current visibility conditions, changes in visibility relative
to baseline (2000-2004) visibility conditions, and changes in
visibility conditions relative to the period addressed in the first
implementation period progress report. Section 51.308(g)(4) applies to
all States and requires an analysis tracking changes in emissions of
pollutants contributing to visibility impairment from all sources and
sectors since the period addressed by the first implementation period
progress report. This provision further specifies the year or years
through which the analysis must extend depending on the type of source
and the platform through which its emission information is reported.
Finally, 40 CFR 51.308(g)(5), which also applies to all States,
requires an assessment of any significant changes in anthropogenic
emissions within or outside the State have occurred since the period
addressed by the first implementation period progress report, including
whether such changes were anticipated and whether they have limited or
impeded expected progress towards reducing emissions and improving
visibility.
1. Alaska Progress Report
As part of the submission, Alaska included a progress report
covering the second half of the first implementation period. The Alaska
submission included five-year averages of the annual values for the
most impaired and clearest days and described the status of measures of
the long-term strategy from the first implementation period.\251\ In
the progress report, Alaska concluded that sufficient progress was made
toward the reasonable progress goals during the first implementation
period.\252\ Alaska stated that the most significant reductions in
sulfur dioxide emissions occurred as a result of the Federal regulation
of sulfur in fuels and the implementation of sulfur fuel limits in
Alaska and internationally with respect to commercial marine vessels.
Alaska's progress report also included emissions data demonstrating the
reductions achieved due to State and Federal controls.\253\
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\251\ Alaska submission, Combined Section III.K.13, Section
III.K.13.J.
\252\ Id., Page III.K.13.J-10.
\253\ Id., Table III.K.13.J-1.
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The EPA proposes to find that Alaska has met the requirements of 40
CFR 51.308(g)(1) and (2) because the submission included a progress
report that described the measures included in the long-term strategy
from the first implementation period, as well as the implementation
status and the emission reductions achieved through such
implementation. The EPA also proposes to find that Alaska has satisfied
the requirements of 40 CFR 51.308(g)(3) because the progress report
included summaries of the visibility conditions and the trend of the 5-
year averages through 2018 at the Alaska Class I areas.\254\
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\254\ Id., Figures III.K.13.J-1, J-2, and J-3.
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Pursuant to section 51.308(g)(4), Alaska provided a summary of
emissions data from sources and activities, including point, nonpoint,
non-road mobile, on-road mobile sources, wildfires, and volcanic
emissions.\255\ Additionally, the EPA included a spreadsheet that
tracks Alaska air pollutant emissions trends data through 2017 for all
National Emissions Inventory pollutants.\256\ The EPA is proposing to
find that this information satisfies the requirements of 51.308(g)(4)
and (5). Therefore, the EPA proposes to approve the progress report
elements pursuant to Alaska's submission as meeting the requirements of
40 CFR 51.308(f)(5) and (g).
---------------------------------------------------------------------------
\255\ Id., Section III.K.13.E Emissions Inventory.
\256\ See Excel spreadsheet of Alaska Air Pollutant Emissions
Trends Data in the docket for this action.
---------------------------------------------------------------------------
I. Requirements for State and Federal Land Manager Coordination
Section 169A(d) of the CAA requires States to consult with FLMs
before holding the public hearing on a proposed regional haze SIP, and
to include a summary of the FLM conclusions and recommendations in the
notice to the public. Section 51.308(i)(2)'s FLM consultation provision
requires a State to provide FLMs with an opportunity for consultation
that is early enough in the State's policy analyses of its emission
reduction obligation so that information and recommendations provided
by the FLMs can meaningfully inform the State's decisions on its long-
term strategy. If the consultation has taken place at least 120 days
before a public hearing or public comment period, the opportunity for
consultation will be deemed early enough, Regardless, the opportunity
for consultation must be provided at least sixty days before a public
hearing or public comment period at the State level. Section
51.308(i)(2) also provides two substantive topics on which FLMs must be
provided an opportunity to discuss with States: assessment of
visibility impairment in any Class I area and recommendations on the
development and implementation of strategies to address visibility
impairment. Section 51.308(i)(3) requires States, in developing their
implementation plans, to include a description of how they addressed
FLM comments.
1. Alaska Consultation and Coordination
The submission made clear that Alaska consulted and coordinated
with the FLMs early and often in the State's
[[Page 48879]]
planning process.\257\ The WRAP hosted State and Federal coordination
calls and technical support system development calls on a routine basis
and representatives from the Alaska DEC regularly participated. The
Alaska DEC gave the FLMs the opportunity to review and comment on both
WRAP-produced technical support system data and technical documentation
developed by contractors supporting the development of the Alaska
submission.\258\
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\257\ Alaska submission, Combined Section III.K.13, Page
III.K.13.K-1.
\258\ Id., Page III.K.13.K-1.
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In 2020 and 2021, the Alaska DEC held six consultation meetings
with the National Park Service, U.S. Forest Service and U.S. Fish and
Wildlife Service.\259\ After two years of engagement, the FLMs agreed
to a 60-day review period for the draft Alaska submission (from May 27,
2021 through July 27, 2021).\260\ Alaska received and responded to
comments from the National Park Service, U.S. Fish and Wildlife
Service, and the EPA during the FLM review period. On March 30, 2022,
Alaska published notice of the availability of the draft submission and
public hearing on the Alaska website.\261\ The Alaska DEC notified the
public, interested parties, the FLMs, air quality contacts from other
States and regions, and the EPA of the availability of the State's
draft submission.\262\ A public hearing on the proposed SIP revision
was held on May 10, 2022, via teleconference. Written comments relevant
to the proposal were accepted until the close of business May 24, 2022.
The Alaska DEC included the comments and responses in the Alaska
submission in Appendix III.K.13.K, which may be found in the docket for
this action.
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\259\ Id., Page III.K.13.K-1.
\260\ Id., Page III.K.13.K-1.
\261\ Id., Page III.K.13.K-4.
\262\ On April 5, 2022, Alaska added the FLM comments and
responses document to the website after inadvertently leaving the
FLM comments and responses off. The Alaska DEC sent an additional
notification to alert all interested parties that the FLM comments
and responses had been uploaded to the website. The Alaska DEC, the
FLMs, and the EPA also met on April 25, 2022, to review the Alaska
plan and provide an opportunity to ask technical questions.
---------------------------------------------------------------------------
Therefore, Alaska complied with the requirements in CAA Section
169A(d) and 40 CFR 51.308(i) to meet with the FLMs prior to holding a
public hearing on the SIP revision and provide the public with the
FLM's comments and the State's responses. Thus, we propose to approve
the submission as meeting the consultation requirements of 40 CFR
51.308(i).
2. Alaska Visibility Protection Area
Because Alaska is geographically large, the Alaska DEC established
a Visibility Protection Area around Alaska's Class I areas \263\ and
promulgated regulations requiring stationary sources in the Visibility
Protection Area to keep records, report more detailed haze-related
data, and potentially implement visibility control measures in the
future based on this data. Alaska revised 18 AAC 50.025 (visibility and
other special protection areas) to add the new Visibility Protection
Area and promulgated a new rule at 18 AAC 50.265 (additional
requirements for construction or operation of title V permitted sources
and operation of minor stationary sources within the regional haze
special protection area) to prescribe the requirements.
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\263\ The Alaska DEC used point source data, WEP data for
NOX and SO2, and jurisdictional boundaries to
establish the visibility protection area that covers more than 80%
of current anthropogenic emissions that may contribute to sulfate
and nitrate on the 20% most impaired days. For the detailed
methodology used to develop the Visibility Protection Area and
boundary, see Alaska submission, Appendix III.K.13.H, Figure
III.K.13.H.1 and Table III.K.13.H.2.
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In this action, as requested by the State, we are proposing to
approve and incorporate by reference into the Alaska SIP at 40 CFR
52.70(c), the two submitted rule sections 18 AAC 50.025 and 18 AAC
50.265, State effective August 21, 2022.
V. Proposed Action
The EPA is proposing to approve the Alaska submission as meeting
the following requirements:
40 CFR 51.308(f)(1)--calculation of baseline, current, and
natural visibility conditions; progress to date; and the uniform rate
of progress;
40 CFR 51.308(f)(2)--long-term strategy requirements;
40 CFR 51.308(f)(3)--reasonable progress goal
requirements;
40 CFR 51.308(f)(4)--additional monitoring needed to
address reasonably attributable visibility impairment;
40 CFR 51.308(f)(5)--progress report requirements;
40 CFR 51.308(f)(6)--monitoring strategy and other plan
requirements;
40 CFR 51.308(g)(1) through (5)--progress report
requirements; and
40 CFR 51.308(i)--State and Federal Land Manager
coordination requirements.
The EPA is also proposing to approve, and incorporate by reference
into the Alaska SIP at 40 CFR 52.70(c), the following submitted
regulations:
18 AAC 50.025 Visibility and other special protection
areas (defining the geographic scope of the regional haze visibility
protection area), State effective August 21, 2022;
18 AAC 50.265 Additional requirements for construction or
operation of title V permitted sources and operation of minor
stationary sources within the regional haze special protection area
(requiring fuel-burning and industrial sources located in the
visibility protection area to save maintenance records, submit
emissions data to the State for purposes of the national emissions
inventory, and in each permit application, provide an assessment of
whether proposed emissions increases may impact the State's reasonable
further progress goals), State effective August 21, 2022.
The EPA is taking this action pursuant to CAA sections 110 and
169A.
VI. Incorporation by Reference
In this document, the EPA is proposing to include regulatory text
in an EPA final rule that includes incorporation by reference. In
accordance with requirements of 1 CFR 51.5, the EPA is proposing to
incorporate by reference the regulatory provisions described in section
V. of this document. The EPA has made, and will continue to make, these
materials generally available through https://www.regulations.gov and
at the EPA Region 10 Office (please contact the person identified in
the FOR FURTHER INFORMATION CONTACT section of this document for more
information).
VII. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the CAA and applicable
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, the EPA's role is to approve State choices,
provided that they meet the criteria of the CAA. Accordingly, this
action merely approves State law as meeting Federal requirements and
does not impose additional requirements beyond those imposed by State
law. For that reason, this action:
Is not a significant regulatory action subject to review
by the Office of Management and Budget under Executive Order 12866 (58
FR 51735, October 4, 1993);
Is not subject to Executive Order 14192 (90 FR 9065,
February 6, 2025) because SIP actions are exempt from review under
Executive Order 12866;
[[Page 48880]]
Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
Is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it approves a State program;
Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001); and
Is not subject to requirements of section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the CAA.
In addition, the SIP is not approved to apply on any Indian
reservation land or in any other area where EPA or an Indian Tribe has
demonstrated that a Tribe has jurisdiction. In those areas of Indian
country, the rule does not have tribal implications and will not impose
substantial direct costs on tribal governments or preempt tribal law as
specified by Executive Order 13175 (65 FR 67249, November 9, 2000).
Consistent with EPA policy, the EPA contacted 24 Tribes located near
Alaska Class I areas and offered an opportunity to consult on a
government-to-government basis prior to this proposed action in letters
dated January 31, 2023. We received no consultation or coordination
requests prior to this proposed action. The letters may be found in the
docket for this action.
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Ozone, Particulate matter,
Reporting and recordkeeping requirements, Sulfur oxides, Volatile
organic compounds.
Authority: 42 U.S.C. 7401 et seq.
Dated: October 17, 2025.
Daniel Opalski,
Deputy Regional Administrator, Region 10.
[FR Doc. 2025-19713 Filed 10-29-25; 8:45 am]
BILLING CODE 6560-50-P