[Federal Register Volume 89, Number 160 (Monday, August 19, 2024)]
[Proposed Rules]
[Pages 67018-67040]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-18174]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R03-OAR-2023-0301; FRL-10191-01-R3]


Approval and Promulgation of Air Quality Implementation Plans; 
Delaware; Regional Haze State Implementation Plan for the Second 
Implementation Period

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA or ``the Agency'') is 
proposing to approve the regional haze State implementation plan (SIP) 
revision submitted by Delaware on August 8, 2022, and supplemented on 
March 7, 2024, as satisfying applicable requirements under the Clean 
Air Act (CAA) and EPA's Regional Haze Rule (RHR) for the program's 
second implementation period. Delaware's SIP submission addresses the 
requirement that States must periodically revise their long-term 
strategies for making reasonable progress towards the national goal of 
preventing any future, and remedying any existing, anthropogenic 
impairment of visibility, including regional haze, in mandatory Class I 
Federal areas. The SIP submission also addresses other applicable 
requirements for the second implementation period of the regional haze 
program. EPA is taking this action pursuant to sections 110 and 169A of 
the CAA.

DATES: Written comments must be received on or before September 18, 
2024.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R03-
OAR-2023-0301 at www.regulations.gov. For comments submitted at 
www.regulations.gov, follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
www.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 (CBI) or other information whose disclosure is restricted 
by statute. Multimedia submissions (audio, video, etc.) must be 
accompanied by a written comment. The written comment is considered the 
official comment and should include discussion of all points you wish 
to make. The EPA will generally not consider comments or comment 
contents located outside of the primary submission (i.e., on the web, 
cloud, or other file sharing system). For additional submission 
methods, please contact the person identified in the FOR FURTHER 
INFORMATION CONTACT section. For the full EPA public comment policy, 
information about CBI or multimedia submissions, and general guidance 
on making effective comments, please visit www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Adam Yarina, U.S. Environmental 
Protection Agency, Air & Radiation Division, U.S. Environmental 
Protection Agency, Region III, Four Penn Center, 1600 John F Kennedy 
Boulevard, Philadelphia, Pennsylvania 19103. The telephone number is 
(215) 814-2108. Mr. Yarina can also be reached via electronic mail at 
[email protected].

SUPPLEMENTARY INFORMATION:

Table of Contents

I. What action is EPA proposing?
II. Background and Requirements for Regional Haze Plans
    A. Regional Haze Background
    B. Roles of Agencies in Addressing Regional Haze
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. EPA's Evaluation of Delaware's Regional Haze Submission for the 
Second Implementation Period
    A. Background on Delaware's First Implementation Period SIP 
Submission

[[Page 67019]]

    B. Delaware's Second Implementation Period SIP Submission and 
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
    a. Delaware's Response to the Six MANE-VU Asks
    b. EPA's Evaluation of Delaware's Response to the Six MANE-VU 
Asks and Compliance With 40 CFR 51.308(f)(2)(i)
    c. Additional Long-Term Strategy Requirements
    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 EPA proposing?

    On August 8, 2022, the Delaware Department of Natural Resources and 
Environmental Control (DNREC) submitted a revision to its SIP to 
address regional haze for the second implementation period; with a 
supplement submitted on March 7, 2024. DNREC made this SIP submission 
to satisfy the requirements of the CAA's regional haze program pursuant 
to CAA sections 169A and 169B and 40 CFR 51.308. EPA is proposing to 
find that the Delaware regional haze SIP submission for the second 
implementation period meets the applicable statutory and regulatory 
requirements and thus proposes to approve Delaware's submission into 
its SIP.

II. Background and Requirements for Regional Haze Plans

A. Regional Haze Background

    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.\1\ CAA 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.'' CAA 169A(a)(1). The CAA further directs EPA to 
promulgate regulations to assure reasonable progress toward meeting 
this national goal. CAA 169A(a)(4). On December 2, 1980, EPA 
promulgated regulations to address visibility impairment in mandatory 
Class I Federal areas (hereinafter referred to as ``Class I Areas'') 
that is ``reasonably attributable'' to a single source or small group 
of sources. (45 FR 80084, December 2, 1980). These regulations, 
codified at 40 Code of Federal Regulations (CFR) 51.300 through 51.307, 
represented the first phase of EPA's efforts to address visibility 
impairment. In 1990, Congress added section 169B to the CAA to further 
address visibility impairment, specifically, impairment from regional 
haze. CAA 169B. EPA promulgated the RHR, codified at 40 CFR 51.308,\2\ 
on July 1, 1999. (64 FR 35714, July 1, 1999). These regional haze 
regulations are a central component of EPA's comprehensive visibility 
protection program for Class I Areas.
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    \1\ Areas statutorily designated as mandatory Class I Federal 
areas consist of national parks exceeding 6,000 acres, wilderness 
areas and national memorial parks exceeding 5,000 acres, and all 
international parks that were in existence on August 7, 1977. CAA 
162(a). There are 156 mandatory Class I Areas. The list of areas to 
which the requirements of the visibility protection program apply is 
in 40 CFR part 81, subpart D.
    \2\ In addition to the generally applicable regional haze 
provisions at 40 CFR 51.308, EPA also promulgated regulations 
specific to addressing regional haze visibility impairment in Class 
I Areas on the Colorado Plateau at 40 CFR 51.309. The latter 
regulations are applicable only for specific jurisdictions' regional 
haze plans submitted no later than December 17, 2007, and thus are 
not relevant here.
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    Regional haze is visibility impairment that is produced by a 
multitude of anthropogenic sources and activities which are located 
across a broad geographic area and that emit pollutants that impair 
visibility. Visibility impairing pollutants include fine and coarse 
particulate matter (PM) (e.g., sulfates, nitrates, organic carbon, 
elemental carbon, and soil dust) and their precursors (e.g., sulfur 
dioxide (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.\3\
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    \3\ 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 to express 
visibility and is measured in inverse megameters (Mm-1). The EPA's 
Guidance on Regional Haze State Implementation Plans for the Second 
Implementation Period (``2019 Guidance'') offers the flexibility for 
the use of light extinction in certain cases. Light extinction can 
be simpler to use in calculations than deciviews since it is not a 
logarithmic function. See, e.g., 2019 Guidance at 16, 19, 
www.epa.gov/visibility/guidance-regional-haze-state-implementation-plans-second-implementation-period, The EPA Office of Air Quality 
Planning and Standards, Research Triangle Park (August 20, 2019). 
The formula for the deciview is 10 ln (b\ext\)/10 Mm-1). 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. CAA 169A(b)(2); \4\ see also 40 CFR 
51.308(b), (f) (establishing submission dates for iterative regional 
haze SIP revisions); (64 FR 35714 at 35768, July 1, 1999). Under the 
CAA, each SIP submission must contain ``a long-term (ten to fifteen 
years) strategy for making reasonable progress toward meeting the 
national goal,'' CAA 169A(b)(2)(B); the initial round of SIP 
submissions also had to address the statutory requirement that certain 
older, larger sources of visibility impairing pollutants install and 
operate the best available retrofit technology (BART). CAA 
169A(b)(2)(A); 40 CFR 51.308(d), (e). States' first regional haze SIPs 
were due by December 17, 2007, 40 CFR 51.308(b), with subsequent SIP 
submissions containing updated long-term strategies originally due July 
31, 2018, and every ten years thereafter. (64 FR 35714 at 35768, July 
1, 1999). EPA established in the 1999 RHR that all States either have 
Class I Areas within their borders or ``contain sources whose emissions 
are reasonably anticipated to contribute to regional haze in a Class I 
Area''; therefore, all States must submit regional haze SIPs.\5\ Id. at 
35721.
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    \4\ The RHR expresses the statutory requirement for states to 
submit plans addressing out-of-state Class I Areas by providing that 
states must address visibility impairment ``in each mandatory Class 
I Federal area located outside the State that may be affected by 
emissions from within the State.'' 40 CFR 51.308(d), (f).
    \5\ In addition to each of the fifty states, the EPA also 
concluded that the Virgin Islands and District of Columbia must also 
submit regional haze SIPs because they either contain a Class I area 
or contain sources whose emissions are reasonably anticipated to 
contribute regional haze in a Class I area. See 40 CFR 51.300(b), 
(d)(3).
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    Much of the focus in the first implementation period of the 
regional haze program, which ran from 2007 through 2018, was on 
satisfying States' BART obligations. First implementation period SIPs 
were additionally required to contain long-term strategies for making 
reasonable progress toward the

[[Page 67020]]

national visibility goal, of which BART is one component. The core 
required elements for the first implementation period SIPs (other than 
BART) are laid out in 40 CFR 51.308(d). Those provisions required that 
States containing Class I Areas establish reasonable progress goals 
(RPGs) that are measured in deciviews and reflect the anticipated 
visibility conditions at the end of the implementation period including 
from implementation of States' long-term strategies. The first planning 
period RPGs were required to provide for an improvement in visibility 
for the most impaired days over the period of the implementation plan 
and ensure no degradation in visibility for the least impaired days 
over the same period. In establishing the RPGs for any Class I Area in 
a State, the State was required to consider four statutory factors: 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. CAA 169A(g)(1); 40 CFR 
51.308(d)(1).
    States were also required to calculate baseline (using the five 
year period of 2000-2004) and natural visibility conditions (i.e., 
visibility conditions without anthropogenic visibility impairment) for 
each Class I Area, and to calculate 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 known as the uniform 
rate of progress (URP) and 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.\6\ 40 CFR 
51.308(d)(1)(i)(B), (d)(2). The 1999 RHR also provided that States' 
long-term strategies must include the ``enforceable emissions 
limitations, compliance schedules, and other measures as necessary to 
achieve the reasonable progress goals.'' 40 CFR 51.308(d)(3). In 
establishing their long-term strategies, States are required to consult 
with other States that also contribute to visibility impairment in a 
given Class I Area and include all measures necessary to obtain their 
shares of the emission reductions needed to meet the RPGs. 40 CFR 
51.308(d)(3)(i) and (ii). Section 51.308(d) also contains seven 
additional factors States must consider in formulating their long-term 
strategies, 40 CFR 51.308(d)(3)(v), as well as provisions governing 
monitoring and other implementation plan requirements. 40 CFR 
51.308(d)(4). Finally, the 1999 RHR required States to submit periodic 
progress reports--SIP revisions due every five years that contain 
information on States' implementation of their regional haze plans and 
an assessment of whether anything additional is needed to make 
reasonable progress, see 40 CFR 51.308(g), (h)--and to consult with the 
Federal Land Manager(s) \7\ (FLMs) responsible for each Class I Area 
according to the requirements in CAA 169A(d) and 40 CFR 51.308(i).
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    \6\ EPA established the URP framework in the 1999 RHR to provide 
``an equitable analytical approach'' to assessing the rate of 
visibility improvement at Class I Areas across the country. The 
start point for the URP analysis is 2004 and the endpoint was 
calculated based on the amount of visibility improvement that was 
anticipated to result from implementation of existing CAA programs 
over the period from the mid-1990s to approximately 2005. Assuming 
this rate of progress would continue into the future, EPA determined 
that natural visibility conditions would be reached in 60 years, or 
2064 (60 years from the baseline starting point of 2004). However, 
EPA did not establish 2064 as the year by which the national goal 
must be reached. 64 FR 35714 at 35731-32, July 1, 1999. That is, the 
URP and the 2064 date are not enforceable targets, but are rather 
tools that ``allow for analytical comparisons between the rate of 
progress that would be achieved by the state's chosen set of control 
measures and the URP.'' (82 FR 3078 at 3084, January 10, 2017).
    \7\ EPA's regulations define ``Federal Land Manager'' as ``the 
Secretary of the department with authority over the Federal Class I 
area (or the Secretary's designee) or, with respect to Roosevelt-
Campobello International Park, the Chairman of the Roosevelt-
Campobello International Park Commission.'' 40 CFR 51.301.
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    On January 10, 2017, EPA promulgated revisions to the RHR, (82 FR 
3078, January 10, 2017), that apply for the second and subsequent 
implementation periods. The 2017 rule made several changes to the 
requirements for regional haze SIPs to clarify States' obligations and 
streamline certain regional haze requirements. The revisions to the 
regional haze program for the second and subsequent implementation 
periods focused on the requirement that States' SIPs contain long-term 
strategies for making reasonable progress towards the national 
visibility goal. The reasonable progress requirements as revised in the 
2017 rule (referred to here as the ``2017 RHR Revisions'') are codified 
at 40 CFR 51.308(f). Among other changes, the 2017 RHR Revisions 
adjusted the deadline for States to submit their second implementation 
period SIPs from July 31, 2018 to July 31, 2021, clarified the order of 
analysis and the relationship between RPGs and the long-term strategy, 
and focused on making visibility improvements on the days with the most 
anthropogenic visibility impairment, as opposed to the days with the 
most visibility impairment overall. EPA also revised requirements of 
the visibility protection program related to periodic progress reports 
and FLM consultation. The specific requirements applicable to second 
implementation period regional haze SIP submissions are addressed in 
detail below.
    EPA provided guidance to the States for their second implementation 
period SIP submissions in the preamble to the 2017 RHR Revisions as 
well as in subsequent, stand-alone guidance documents. In August 2019, 
the EPA issued ``Guidance on Regional Haze State Implementation Plans 
for the Second Implementation Period'' (``2019 Guidance'').\8\ On July 
8, 2021, EPA issued a memorandum containing ``Clarifications Regarding 
Regional Haze State Implementation Plans for the Second Implementation 
Period'' (``2021 Clarifications Memo'').\9\ Additionally, EPA further 
clarified the recommended procedures for processing ambient visibility 
data and optionally adjusting the URP to account for international 
anthropogenic and prescribed fire impacts in two technical guidance 
documents: the December 2018 ``Technical Guidance on Tracking 
Visibility Progress for the Second Implementation Period of the 
Regional Haze Program'' (``2018 Visibility Tracking Guidance''),\10\ 
and the June 2020 ``Recommendation for the Use of Patched and 
Substituted Data and Clarification of Data Completeness for Tracking 
Visibility Progress for the Second Implementation Period of the 
Regional Haze Program'' and associated Technical Addendum (``2020 Data 
Completeness Memo'').\11\
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    \8\ Guidance on Regional Haze State Implementation Plans for the 
Second Implementation Period. www.epa.gov/visibility/guidance-regional-haze-state-implementation-plans-second-implementation-period. The EPA Office of Air Quality Planning and Standards, 
Research Triangle Park (August 20, 2019).
    \9\ Clarifications Regarding Regional Haze State Implementation 
Plans for the Second Implementation Period. www.epa.gov/system/files/documents/2021-07/clarifications-regarding-regional-haze-state-implementation-plans-for-the-second-implementation-period.pdf. 
The EPA Office of Air Quality Planning and Standards, Research 
Triangle Park (July 8, 2021).
    \10\ Technical Guidance on Tracking Visibility Progress for the 
Second Implementation Period of the Regional Haze Program. 
www.epa.gov/visibility/technical-guidance-tracking-visibility-progress-second-implementation-period-regional. The EPA Office of 
Air Quality Planning and Standards, Research Triangle Park. 
(December 20, 2018).
    \11\ Recommendation for the Use of Patched and Substituted Data 
and Clarification of Data Completeness for Tracking Visibility 
Progress for the Second Implementation Period of the Regional Haze 
Program. www.epa.gov/visibility/memo-and-technical-addendum-ambient-data-usage-and-completeness-regional-haze-program. The EPA Office of 
Air Quality Planning and Standards, Research Triangle Park (June 3, 
2020).

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[[Page 67021]]

    As previously explained in the 2021 Clarifications Memo, EPA 
intends the second implementation period of the regional haze program 
to secure meaningful reductions in visibility impairing pollutants that 
build on the significant progress States have achieved to date. The 
Agency also recognizes that analyses regarding reasonable progress are 
State-specific and that, based on States' and sources' individual 
circumstances, what constitutes reasonable reductions in visibility 
impairing pollutants will vary from state-to-state. While there exist 
many opportunities for States to leverage both ongoing and upcoming 
emission reductions under other CAA programs, the Agency expects States 
to undertake rigorous reasonable progress analyses that identify 
further opportunities to advance the national visibility goal 
consistent with the statutory and regulatory requirements. See 
generally 2021 Clarifications Memo. This is consistent with Congress' 
determination that a visibility protection program is needed in 
addition to the CAA's National Ambient Air Quality Standards and 
Prevention of Significant Deterioration programs, as further emission 
reductions may be necessary to adequately protect visibility in Class I 
Areas throughout the country.\12\
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    \12\ See, e.g., H.R. Rep No. 95-294 at 205 (``In determining how 
to best remedy the growing visibility problem in these areas of 
great scenic importance, the committee realizes that as a matter of 
equity, the national ambient air quality standards cannot be revised 
to adequately protect visibility in all areas of the country.''), 
(``the mandatory class I increments of [the PSD program] do not 
adequately protect visibility in Class I Areas'').
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B. Roles of Agencies in Addressing Regional Haze

    Because the air pollutants and pollution affecting visibility in 
Class I Areas can be transported over long distances, successful 
implementation of the regional haze program requires long-term, 
regional coordination among multiple jurisdictions and agencies that 
have responsibility for Class I Areas and the emissions that impact 
visibility in those areas. In order to address regional haze, States 
need to develop strategies in coordination with one another, 
considering the effect of emissions from one jurisdiction on the air 
quality in another. Five regional planning organizations (RPOs),\13\ 
which include representation from State and Tribal governments, EPA, 
and FLMs, were developed in the lead-up to the first implementation 
period to address regional haze. RPOs evaluate technical information to 
better understand how emissions from State and Tribal land impact Class 
I Areas across the country, pursue the development of regional 
strategies to reduce emissions of particulate matter and other 
pollutants leading to regional haze, and help States meet the 
consultation requirements of the RHR.
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    \13\ RPOs are sometimes also referred to as ``multi-
jurisdictional organizations,'' or MJOs. For the purposes of this 
rulemaking, the terms RPO and MJO are synonymous.
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    The Mid-Atlantic/Northeast Visibility Union (MANE-VU), one of the 
five RPOs described above, is a collaborative effort of State 
governments, Tribal governments, and various Federal agencies 
established to initiate and coordinate activities associated with the 
management of regional haze, visibility, and other air quality issues 
in the Mid-Atlantic and Northeast corridor of the United States. Member 
States and Tribal governments (listed alphabetically) include: 
Connecticut, Delaware, the District of Columbia, Maine, Maryland, 
Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, 
Penobscot Indian Nation, Rhode Island, St. Regis Mohawk Tribe, and 
Vermont. The Federal partner members of MANE-VU are EPA, U.S. National 
Parks Service (NPS), U.S. Fish and Wildlife Service (FWS), and U.S. 
Forest Service (USFS).

III. Requirements for Regional Haze Plans for the Second Implementation 
Period

    Under the CAA and EPA's regulations, all 50 States, the District of 
Columbia, and the U.S. Virgin Islands are required to submit regional 
haze SIPs satisfying the applicable requirements for the second 
implementation period of the regional haze program by July 31, 2021. 
Each State's SIP must contain a long-term strategy for making 
reasonable progress toward meeting the national goal of remedying any 
existing and preventing any future anthropogenic visibility impairment 
in Class I Areas. CAA 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 \14\ and paragraphs (f)(4) through (6) 
containing additional, related requirements. 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, current, and natural visibility conditions for 
that area, as well as the visibility improvement made to date and the 
URP. 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. See 40 CFR 51.308(f)(2). A State evaluates 
potential emission reduction measures for those selected sources and 
determines which are necessary to make reasonable progress. Those 
measures are then incorporated into the State's long-term strategy. 
After a State has developed its long-term strategy, it then establishes 
RPGs for each Class I Area within its borders by modeling the 
visibility impacts of all reasonable progress controls at the end of 
the second implementation period, i.e., in 2028, as well as the impacts 
of other requirements of the 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).
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    \14\ EPA explained in the 2017 RHR Revisions 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.'' (82 FR 3078 at 3091, January 10, 2017).
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    In addition to satisfying the requirements at 40 CFR 51.308(f) 
related to reasonable progress, the regional haze SIP revisions for the 
second implementation period must address the requirements in 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. 40 CFR 51.308(i).
    A State must submit its regional haze SIP and subsequent SIP 
revisions to

[[Page 67022]]

EPA according to the requirements applicable to all SIP revisions under 
the CAA and EPA's regulations. See CAA 169A(b)(2); CAA 110(a). Upon EPA 
approval, a SIP is enforceable by the Agency and the public under the 
CAA. If EPA finds that a State fails to make a required SIP revision, 
or if EPA finds that a State's SIP is incomplete or disapproves the 
SIP, the Agency must promulgate a Federal implementation plan (FIP) 
that satisfies the applicable requirements. CAA 110(c)(1).

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, EPA determined that all States contribute to visibility impairment 
in at least one Class I Area, 64 FR 35714 at 35720-22 (July 1, 1999), 
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.'' Id. at 35721.
    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. While the RHR does not 
require this evaluation to be conducted in any particular manner, EPA's 
2019 Guidance provides recommendations for how such an assessment might 
be accomplished, including by, where appropriate, using the 
determinations previously made for the first implementation period. 
2019 Guidance at 8-9. In addition, the determination of which Class I 
Areas may be affected by a State's emissions is subject to the 
requirement in 40 CFR 51.308(f)(2)(iii) to ``document the technical 
basis, including modeling, monitoring, cost, engineering, and emissions 
information, on which the State is relying to determine the emission 
reduction measures that are necessary to make reasonable progress in 
each mandatory Class I Federal Area it affects.''

B. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress

    As part of assessing whether a SIP submission 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. EPA's 2018 Visibility Tracking Guidance \15\ 
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 at 3103-05 (January 10, 2017).
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    \15\ The 2018 Visibility Tracking Guidance references and relies 
on parts of the 2003 Tracking Guidance: ``Guidance for Tracking 
Progress Under the Regional Haze Rule,'' which can be found at 
www.epa.gov/sites/default/files/2021-03/documents/tracking.pdf.
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    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 20% most impaired days (the 20% of monitored days 
in a calendar year with the highest amounts of anthropogenic visibility 
impairment).\16\ 40 CFR 51.301. A State must calculate visibility 
conditions for both the 20% clearest and 20% most impaired days for the 
baseline period of 2000-2004 and the most recent five-year period for 
which visibility monitoring data are available (representing current 
visibility conditions). 40 CFR 51.308(f)(1)(i) and (iii). States must 
also calculate natural visibility conditions for the clearest and most 
impaired days,\17\ 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 in order 
to reach natural visibility conditions.
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    \16\ This rulemaking also refers to the 20% clearest and 20% 
most anthropogenically impaired days as the ``clearest'' and ``most 
impaired'' or ``most anthropogenically impaired'' days, 
respectively.
    \17\ The RHR at 40 CFR 51.308(f)(1)(ii) contains an error 
related to the requirement for calculating two sets of natural 
conditions values. The rule says ``most impaired days or the 
clearest days'' where it should say ``most impaired days and 
clearest days.'' This is an error that was intended to be corrected 
in the 2017 RHR Revisions but did not get corrected in the final 
rule language. This is supported by the preamble text at 82 FR 3078 
at 3098: ``In the final version of 40 CFR 51.308(f)(1)(ii), an 
occurrence of ``or'' has been corrected to ``and'' to indicate that 
natural visibility conditions for both the most impaired days and 
the clearest days must be based on available monitoring 
information.''
---------------------------------------------------------------------------

    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 in order 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.\18\ Additionally, in the 2017 RHR Revisions, 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, which must be approved by EPA, are intended to avoid any 
perception that States should compensate for impacts from international 
anthropogenic sources and to give States the flexibility to determine 
that limiting the use of wildland-prescribed fire is not necessary for 
reasonable progress. See 82 FR 3078 at 3107, January 10, 2017, footnote 
116.
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    \18\ Being on or below the URP is not a ``safe harbor''; i.e., 
achieving the URP does not mean that a Class I area is making 
``reasonable progress'' and does not relieve a state from using the 
four statutory factors to determine what level of control is needed 
to achieve such progress. See, e.g., 82 FR 3078 at 3093 (January 10, 
2017).
---------------------------------------------------------------------------

    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 40 CFR 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 submission is a long-term 
strategy that addresses regional haze in each Class I Area within a 
State's

[[Page 67023]]

borders and each Class I Area that may be affected by emissions from 
the State. The long-term strategy ``must include the enforceable 
emissions limitations, compliance schedules, and other measures that 
are necessary to make reasonable progress, as determined pursuant to 
(f)(2)(i) through (iv).'' 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 in order 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 2019 Guidance at 43; 2021 Clarifications Memo at 8-
10. 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).
    Section 51.308(f)(2)(i) provides the requirements for the four-
factor analysis. The first step of this analysis entails selecting the 
sources to be evaluated for emission reduction measures; to this end, 
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. As EPA 
previously explained, consistent with the first implementation period, 
EPA generally expects that each State will analyze at least 
SO2 and NOX in selecting sources and determining 
control measures. See 2019 Guidance at 12, 2021 Clarifications Memo at 
4. A State that chooses not to consider at least these two pollutants 
should demonstrate why such consideration would be unreasonable. 2021 
Clarifications Memo at 4.
    While States have the option to analyze all sources, the 2019 
Guidance explains that ``an analysis of control measures is not 
required for every source in each implementation period,'' and that 
``[s]electing a set of sources for analysis of control measures in each 
implementation period is . . . consistent with the Regional Haze Rule, 
which sets up an iterative planning process and anticipates that a 
State may not need to analyze control measures for all its sources in a 
given SIP revision.'' 2019 Guidance at 9. However, given that source 
selection is the basis of all subsequent control determinations, a 
reasonable source selection process ``should be designed and conducted 
to ensure that source selection results in a set of pollutants and 
sources the evaluation of which has the potential to meaningfully 
reduce their contributions to visibility impairment.'' 2021 
Clarifications Memo at 3.
    EPA explained in the 2021 Clarifications Memo that each State has 
an obligation to submit a long-term strategy that addresses the 
regional haze visibility impairment that results from emissions from 
within that State. Thus, source selection should focus on the in-State 
contribution to visibility impairment and be designed to capture a 
meaningful portion of the State's total contribution to visibility 
impairment in Class I Areas. A State should not decline to select its 
largest in-State sources on the basis that there are even larger out-
of-State contributors. 2021 Clarifications Memo at 4.\19\
---------------------------------------------------------------------------

    \19\ Similarly, in responding to comments on the 2017 RHR 
Revisions EPA explained that ``[a] state should not fail to address 
its many relatively low-impact sources merely because it only has 
such sources and another state has even more low-impact sources and/
or some high impact sources.'' Responses to Comments on Protection 
of Visibility: Amendments to Requirements for State Plans; Proposed 
Rule (81 FR 26942, May 4, 2016) at 26987-26988.
---------------------------------------------------------------------------

    Thus, 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.\20\ This is accomplished by considering the four factors--``the 
costs of compliance, the time necessary for compliance, and the energy 
and nonair quality environmental impacts of compliance, and the 
remaining useful life of any existing source subject to such 
requirements.'' CAA 169A(g)(1). EPA has explained that the four-factor 
analysis is an assessment of potential emission reduction measures 
(i.e., control options) for sources; ``use of the terms `compliance' 
and `subject to such requirements' in section 169A(g)(1) strongly 
indicates that Congress intended the relevant determination to be the 
requirements with which sources would have to comply in order to 
satisfy the CAA's reasonable progress mandate.'' 82 FR 3078 at 3091 
(January 10, 2017). Thus, for each source it has selected for four-
factor analysis,\21\ a State must consider a ``meaningful set'' of 
technically feasible control options for reducing emissions of 
visibility impairing pollutants. Id. at 3088. The 2019 Guidance 
provides that ``[a] state must reasonably pick and justify the measures 
that it will consider, recognizing that there is no statutory or 
regulatory requirement to consider all technically feasible measures or 
any particular measures. A range of technically feasible measures 
available to reduce emissions would be one way to justify a reasonable 
set.'' 2019 Guidance at 29.
---------------------------------------------------------------------------

    \20\ The CAA provides that, ``[i]n determining reasonable 
progress there shall be taken into consideration'' the four 
statutory factors. CAA 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.
    \21\ ``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 at 3088, January 10, 2017. However, not all approaches to 
grouping sources for four-factor analysis are necessarily 
reasonable; the reasonableness of grouping sources in any particular 
instance will depend on the circumstances and the manner in which 
grouping is conducted. If it is feasible to establish and enforce 
different requirements for sources or subgroups of sources, and if 
relevant factors can be quantified for those sources or subgroups, 
then States should make a separate reasonable progress determination 
for each source or subgroup. 2021 Clarifications Memo at 7-8.
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    EPA's 2021 Clarifications Memo provides further guidance on what 
constitutes a reasonable set of control options for consideration: ``A 
reasonable four-factor analysis will consider the full range of 
potentially reasonable options for reducing emissions.'' 2021

[[Page 67024]]

Clarifications Memo at 7. In addition to add-on controls and other 
retrofits (i.e., new emission reduction measures for sources), EPA 
explained that States should generally analyze efficiency improvements 
for sources' existing measures as control options in their four-factor 
analyses, as in many cases such improvements are reasonable given that 
they typically involve only additional operation and maintenance costs. 
Additionally, the 2021 Clarifications Memo provides that States that 
have assumed a higher emission rate than a source has achieved or could 
potentially achieve using its existing measures should also consider 
lower emission rates as potential control options. That is, a State 
should consider a source's recent actual and projected emission rates 
to determine if it could reasonably attain lower emission rates with 
its existing measures. If so, the State should analyze the lower 
emission rate as a control option for reducing emissions. 2021 
Clarifications Memo at 7. EPA's recommendations to analyze potential 
efficiency improvements and achievable lower emission rates apply to 
both sources that have been selected for four-factor analysis and those 
that have forgone a four-factor analysis on the basis of existing 
``effective controls.'' See 2021 Clarifications Memo at 5, 10.
    After identifying a reasonable set of potential control options for 
the sources it has selected, a State then collects information on the 
four factors with regard to each option identified. 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.\22\ The 2019 Guidance provides recommendations for the types 
of information that can be used to characterize the four factors (with 
or without visibility), as well as ways in which States might 
reasonably consider and balance that information to determine which of 
the potential control options is necessary to make reasonable progress. 
See 2019 Guidance at 30-36. The 2021 Clarifications Memo contains 
further guidance on how States can reasonably consider modeled 
visibility impacts or benefits in the context of a four-factor 
analysis. 2021 Clarifications Memo at 12-13, 14-15. Specifically, EPA 
explained that while visibility can reasonably be used when comparing 
and choosing between multiple reasonable control options, it should not 
be used to summarily reject controls that are reasonable given the four 
statutory factors. 2021 Clarifications Memo at 13. 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.''
---------------------------------------------------------------------------

    \22\ See, e.g., Responses to Comments on Protection of 
Visibility: Amendments to Requirements for State Plans; Proposed 
Rule (81 FR 26942, May 4, 2016), Docket Number EPA-HQ-OAR-2015-0531, 
U.S. Environmental Protection Agency at 186; 2019 Guidance at 36-37.
---------------------------------------------------------------------------

    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.\23\ If the 
outcome of a four-factor analysis is a new, additional emission 
reduction measure for a source, that new measure is necessary to make 
reasonable progress towards remedying existing anthropogenic visibility 
impairment and must be included in the SIP. If the outcome of a four-
factor analysis is that no new measures are reasonable for a source, 
continued implementation of the source's existing measures is generally 
necessary to prevent future emission increases and thus to make 
reasonable progress towards the second part of the national visibility 
goal: preventing future anthropogenic visibility impairment. See CAA 
169A(a)(1). That is, when the result of a four-factor analysis is that 
no new measures are necessary to make reasonable progress, the source's 
existing measures are generally necessary to make reasonable progress 
and must be included in the SIP. However, there may be circumstances in 
which a State can demonstrate that a source's existing measures are not 
necessary to make reasonable progress. Specifically, if a State can 
demonstrate that a source will continue to implement its existing 
measures and will not increase its emission rate, it may not be 
necessary to have those measures in the long-term strategy in order to 
prevent future emission increases and future visibility impairment. 
EPA's 2021 Clarifications Memo provides further explanation and 
guidance on how States may demonstrate that a source's existing 
measures are not necessary to make reasonable progress. See 2021 
Clarifications Memo at 8-10. If the State can make such a 
demonstration, it need not include a source's existing measures in the 
long-term strategy or its SIP.
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    \23\ States may choose to, but are not required to, include 
measures in their long-term strategies beyond just the emission 
reduction measures that are necessary for reasonable progress. See 
2021 Clarifications Memo at 16. For example, states with smoke 
management programs may choose to submit their smoke management 
plans to EPA for inclusion in their SIPs but are not required to do 
so. See, e.g., 82 FR 3078 at 3108-09, January 10, 2017 (requirement 
to consider smoke management practices and smoke management programs 
under 40 CFR 51.308(f)(2)(iv) does not require states to adopt such 
practices or programs into their SIPs, although they may elect to do 
so).
---------------------------------------------------------------------------

    As with source selection, the characterization of information on 
each of the factors is also subject to the documentation requirement in 
40 CFR 51.308(f)(2)(iii). The reasonable progress analysis, including 
source selection, information gathering, characterization of the four 
statutory factors (and potentially visibility), balancing of the four 
factors, and selection of the emission reduction measures that 
represent reasonable progress, is a technically complex exercise, but 
also a flexible one that provides States with bounded discretion to 
design and implement approaches appropriate to their circumstances. 
Given this flexibility, 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 EPA can comprehend and evaluate 
the information and analysis the State relied upon to determine what 
emission reduction measures must be in place to make reasonable 
progress. The technical documentation must include the modeling, 
monitoring, cost, engineering, and emissions information on which the 
State relied to determine the measures necessary to make reasonable 
progress. This documentation requirement can be met through the 
provision of and reliance on technical analyses developed through a 
regional planning process, so long as that process and its output has 
been approved by all State participants. In addition to the explicit 
regulatory requirement to document the technical basis of their 
reasonable progress determinations, States are also subject to the 
general principle that those determinations must be reasonably moored 
to the statute.\24\ That is, a State's decisions about the emission

[[Page 67025]]

reduction measures that are necessary to make reasonable progress must 
be consistent with the statutory goal of remedying existing and 
preventing future visibility impairment.
---------------------------------------------------------------------------

    \24\ See Arizona ex rel. Darwin v. U.S. EPA, 815 F.3d 519, 531 
(9th Cir. 2016); Nebraska v. U.S. EPA, 812 F.3d 662, 668 (8th Cir. 
2016); North Dakota v. EPA, 730 F.3d 750, 761 (8th Cir. 2013); 
Oklahoma v. EPA, 723 F.3d 1201, 1206, 1208-10 (10th Cir. 2013); cf. 
also Nat'l Parks Conservation Ass'n v. EPA, 803 F.3d 151, 165 (3d 
Cir. 2015); Alaska Dep't of Envtl. Conservation v. EPA, 540 U.S. 
461, 485, 490 (2004).
---------------------------------------------------------------------------

    The four statutory factors (and potentially visibility) are used to 
determine what emission reduction measures for selected sources must be 
included in a State's long-term strategy for making reasonable 
progress. Additionally, the RHR at 40 CFR 51.308(f)(2)(iv) separately 
provides five ``additional factors'' \25\ 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. The 2019 Guidance provides that a State may satisfy 
this requirement by considering these additional factors in the process 
of selecting sources for four-factor analysis, when performing that 
analysis, or both, and that not every one of the additional factors 
needs to be considered at the same stage of the process. See 2019 
Guidance at 21. EPA provided further guidance on the five additional 
factors in the 2021 Clarifications Memo, explaining that a State should 
generally not reject cost-effective and otherwise reasonable controls 
merely because there have been emission reductions since the first 
planning period owing to other ongoing air pollution control programs 
or merely because visibility is otherwise projected to improve at Class 
I Areas. Additionally, States should not rely on these additional 
factors to summarily assert that the State has already made sufficient 
progress and, therefore, no sources need to be selected or no new 
controls are needed regardless of the outcome of four-factor analyses. 
2021 Clarifications Memo at 13.
---------------------------------------------------------------------------

    \25\ 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.
---------------------------------------------------------------------------

    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. 
Consultation allows for each State that impacts visibility in an area 
to share whatever technical information, analyses, and control 
determinations may be necessary to develop coordinated emission 
management strategies. This coordination may be managed through inter- 
and intra-RPO consultation and the development of regional emissions 
strategies; additional consultations between States outside of RPO 
processes may also occur. If a State, pursuant to consultation, agrees 
that certain measures (e.g., a certain emission limitation) are 
necessary to make reasonable progress at a Class I Area, it must 
include those measures in its SIP. 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). EPA will consider the technical information 
and explanations presented by the submitting State and the State with 
which it disagrees when considering whether to approve the State's SIP. 
See id.; 2019 Guidance at 53. Under all circumstances, a State must 
document in its SIP submission all substantive consultations with other 
contributing States. 40 CFR 51.308(f)(2)(ii)(C).

D. Reasonable Progress Goals

    Reasonable progress goals ``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 at 3091 (January 10, 2017). Their primary 
purpose is to assist the public and EPA in assessing the reasonableness 
of States' long-term strategies for making reasonable progress towards 
the national visibility goal. See 40 CFR 51.308(f)(3)(iii) and (iv). 
States in which Class I Areas are located must establish two RPGs, both 
in deciviews--one representing visibility conditions on the clearest 
days and one representing visibility on the most anthropogenically 
impaired days--for each area within their borders. 40 CFR 
51.308(f)(3)(i). The two RPGs are intended to reflect the projected 
impacts, on the two sets of days, of the emission reduction measures 
the State with the Class I Area, as well as all other contributing 
States, have included in their long-term strategies for the second 
implementation period.\26\ The RPGs also account for the projected 
impacts of implementing other CAA requirements, including non-SIP based 
requirements. Because RPGs are the modeled result of the measures in 
States' long-term strategies (as well as other measures required under 
the CAA), they cannot be determined before States have conducted their 
four-factor analyses and determined the control measures that are 
necessary to make reasonable progress. See 2021 Clarifications Memo at 
6.
---------------------------------------------------------------------------

    \26\ RPGs are intended to reflect the projected impacts of the 
measures all contributing states include in their long-term 
strategies. However, due to the timing of analyses, control 
determinations by other states, and other on-going emissions 
changes, a particular state's RPGs may not reflect all control 
measures and emissions reductions that are expected to occur by the 
end of the implementation period. The 2019 Guidance provides 
recommendations for addressing the timing of RPG calculations when 
states are developing their long-term strategies on disparate 
schedules, as well as for adjusting RPGs using a post-modeling 
approach. 2019 Guidance at 47-48.
---------------------------------------------------------------------------

    For the second implementation period, the RPGs are set for 2028. 
Reasonable progress goals are not enforceable targets, 40 CFR 
51.308(f)(3)(iii); rather, they ``provide a way for the states to check 
the projected outcome of the [long-term strategy] against the goals for 
visibility improvement.'' 2019 Guidance at 46. 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.'' Thus, States are required to have emission 
reduction measures in their long-term strategies that are projected to 
achieve visibility conditions on the most impaired days that are better 
than the baseline period and show no degradation on the clearest days 
compared to the clearest days from the baseline period. The baseline 
period for the purpose of this comparison is the baseline visibility 
condition--the annual average visibility condition for the period 2000-
2004. See 40 CFR 51.308(f)(1)(i), 82 FR 3078 at 3097-98 (January 10, 
2017).
    So that RPGs may also serve as a metric for assessing the amount of 
progress a State is making towards the

[[Page 67026]]

national visibility goal, 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.'' The 2019 Guidance provides suggestions about how such 
a ``robust demonstration'' might be conducted. See 2019 Guidance at 50-
51.
    The 2017 RHR, 2019 Guidance, and 2021 Clarifications Memo also 
explain that projecting an RPG that is on or below the URP based on 
only on-the-books and/or on-the-way control measures (i.e., control 
measures already required or anticipated before the four-factor 
analysis is conducted) is not a ``safe harbor'' from the CAA's and 
RHR's requirement that all States must conduct a four-factor analysis 
to determine what emission reduction measures constitute reasonable 
progress. The URP is a planning metric used to gauge the amount of 
progress made thus far and the amount left before reaching natural 
visibility conditions. However, the URP is not based on consideration 
of the four statutory factors and therefore cannot answer the question 
of whether the amount of progress being made in any particular 
implementation period is ``reasonable progress.'' See 82 FR 3078 at 
3093, 3099-3100 (January 10, 2017); 2019 Guidance at 22; 2021 
Clarifications Memo at 15-16.

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. A State with Class I Areas within its 
borders must submit with its SIP revision a monitoring strategy for 
measuring, characterizing, and reporting regional haze visibility 
impairment that is representative of all Class I Areas within the 
State. SIP revisions for such States must also provide for the 
establishment of any additional monitoring sites or equipment needed to 
assess visibility conditions in Class I Areas, as well as reporting of 
all visibility monitoring data to EPA at least annually. Compliance 
with the monitoring strategy requirement may be met through a State's 
participation in the Interagency Monitoring of Protected Visual 
Environments (IMPROVE) monitoring network, which is used to measure 
visibility impairment caused by air pollution at the 156 Class I Areas 
covered by the visibility program. 40 CFR 51.308(f)(6), (f)(6)(i) and 
(iv). The IMPROVE monitoring data is used to determine the 20% most 
anthropogenically impaired and 20% clearest sets of days every year at 
each Class I Area and tracks visibility impairment over time.
    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. 40 CFR 51.308(f)(6)(ii) and (iii). Section 
51.308(f)(6)(v) further requires that all States' SIPs provide for a 
statewide inventory of emissions of pollutants that are reasonably 
anticipated to cause or contribute to visibility impairment in any 
Class I Area; the inventory must include emissions for the most recent 
year for which data are available and estimates of future projected 
emissions. States must also include commitments to update their 
inventories periodically. The inventories themselves do not need to be 
included as elements in the SIP and are not subject to EPA review as 
part of the Agency's evaluation of a SIP revision.\27\ 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). Per the 2019 
Guidance, a State may note in its regional haze SIP that its compliance 
with the Air Emissions Reporting Rule (AERR) in 40 CFR part 51, subpart 
A satisfies the requirement to provide for an emissions inventory for 
the most recent year for which data are available. To satisfy the 
requirement to provide estimates of future projected emissions, a State 
may explain in its SIP how projected emissions were developed for use 
in establishing RPGs for its own and nearby Class I Areas.\28\
---------------------------------------------------------------------------

    \27\ See ``Step 8: Additional requirements for regional haze 
SIPs'' in 2019 Regional Haze Guidance at 55.
    \28\ Id.
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    Separate from the requirements related to monitoring for regional 
haze purposes under 40 CFR 51.308(f)(6), the RHR also contains a 
requirement at 40 CFR 51.308(f)(4) related to any additional monitoring 
that may be needed to address visibility impairment in Class I Areas 
from a single source or a small group of sources. This is called 
``reasonably attributable visibility impairment.'' \29\ Under this 
provision, if EPA or the FLM of an affected Class I Area has advised a 
State that additional monitoring is needed to assess reasonably 
attributable visibility impairment, the State must include in its SIP 
revision for the second implementation period an appropriate strategy 
for evaluating such impairment.
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    \29\ EPA's visibility protection regulations define ``reasonably 
attributable visibility impairment'' as ``visibility impairment that 
is caused by the emission of air pollutants from one, or a small 
number of sources.'' 40 CFR 51.301.
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F. Requirements for Periodic Reports Describing Progress Towards the 
Reasonable Progress Goals

    Section 51.308(f)(5) requires a State's regional haze SIP revision 
to address the requirements of paragraphs 40 CFR 51.308(g)(1) through 
(5) so that the plan revision due in 2021 will serve also as a progress 
report addressing the period since submission of the progress report 
for the first implementation period. The regional haze progress report 
requirement is designed to inform the public and 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, 26950 (May 4, 2016), (82 FR 3078 at 3119, 
January 10, 2017). To this end, every State's SIP revision for the 
second implementation period is required to describe the status of 
implementation of all measures included in the State's long-term 
strategy, including BART and reasonable progress emission reduction 
measures from the first implementation

[[Page 67027]]

period, and the resulting emissions reductions. 40 CFR 51.308(g)(1) and 
(2).
    A core component of the progress report requirements is an 
assessment of changes in visibility conditions on the clearest and most 
impaired days. For second implementation period progress reports, 40 
CFR 51.308(g)(3) requires States with Class I Areas within their 
borders to first determine current visibility conditions for each area 
on the most impaired and clearest days, 40 CFR 51.308(g)(3)(i), and 
then to calculate the difference between those current conditions and 
baseline (2000-2004) visibility conditions in order to assess progress 
made to date. See 40 CFR 51.308(g)(3)(ii). States must also assess the 
changes in visibility impairment for the most impaired and clearest 
days since they submitted their first implementation period progress 
reports. See 40 CFR 51.308(g)(3)(iii), (f)(5). Since different States 
submitted their first implementation period progress reports at 
different times, the starting point for this assessment will vary State 
by State.
    Similarly, States must provide analyses tracking the change in 
emissions of pollutants contributing to visibility impairment from all 
sources and activities within the State over the period since they 
submitted their first implementation period progress reports. See 40 
CFR 51.308(g)(4), (f)(5). Changes in emissions should be identified by 
the type of source or activity. Section 51.308(g)(5) also addresses 
changes in emissions since the period addressed by the previous 
progress report and requires States' SIP revisions to include an 
assessment of any significant changes in anthropogenic emissions within 
or outside the State. This assessment must include an explanation of 
whether these changes in emissions were anticipated and whether they 
have limited or impeded progress in reducing emissions and improving 
visibility relative to what the State projected based on its long-term 
strategy for the first implementation period.

G. Requirements for State and Federal Land Manager Coordination

    Clean Air Act section 169A(d) requires that before a State holds a 
public hearing on a proposed regional haze SIP revision, it must 
consult with the appropriate 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). Consultation that occurs 
120 days prior to any public hearing or public comment opportunity will 
be deemed ``early enough,'' but the RHR provides that in any event the 
opportunity for consultation must be provided at least 60 days before a 
public hearing or comment opportunity. This consultation must include 
the opportunity for the FLMs to discuss their assessment of visibility 
impairment in any Class I Area and their recommendations on the 
development and implementation of strategies to address such 
impairment. 40 CFR 51.308(i)(2). In order for 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 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. EPA's Evaluation of Delaware's Regional Haze Submission for the 
Second Implementation Period

A. Background on Delaware's First Implementation Period SIP Submission

    DNREC submitted its regional haze SIP for the first implementation 
period to EPA on September 25, 2008. EPA approved Delaware's first 
implementation period regional haze SIP submission on July 19, 2011 (76 
FR 42557). Delaware has no Class I Areas within its borders but was 
identified as influencing the visibility impairment of the Brigantine 
National Wildlife Refuge Class I Area (``Brigantine'' or ``Brigantine 
Wilderness Class I Area''), located in the State of New Jersey. EPA's 
approval included the portions of the plan that addressed the 
reasonable progress requirements and Delaware's implementation of Best 
Available Retrofit Technologies (BART) on eligible sources. The 
requirements for regional haze SIPs for the first implementation period 
are contained in 40 CFR 51.308(d) and (e). 40 CFR 51.308(b). Pursuant 
to 40 CFR 51.308(g), Delaware was also responsible for submitting a 
five-year progress report as a SIP revision for the first 
implementation period, which it did on September 24, 2013. EPA approved 
the progress report into the Delaware SIP on May 5, 2014. See 79 FR 
25506.

B. Delaware's Second Implementation Period SIP Submission and EPA's 
Evaluation

    In accordance with CAA sections 169A and the RHR at 40 CFR 
51.308(f), on August 8, 2022, DNREC submitted a revision to the 
Delaware SIP, titled ``Delaware's Visibility SIP Revision Final August 
2022'' to address its regional haze obligations for the second 
implementation period, which runs through 2028. DNREC subsequently 
submitted a supplemental SIP submittal to EPA on March 7, 2024, 
referred to as ``Supplemental Submission for Delaware's Second Regional 
Haze SIP'', which included title V permit provisions for three 
facilities owned by Calpine Mid-Atlantic Generation, LLC to be 
incorporated into the Delaware SIP. These permits and their associated 
public notice and transmittal letters are included in the rulemaking 
docket for this action.\30\
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    \30\ DNREC provided a clarification of this supplemental SIP 
submittal on May 28, 2024, that specified which provisions of the 
Title V permits it intended to be incorporated by reference into the 
Delaware SIP.
---------------------------------------------------------------------------

    The following sections describe Delaware's SIP submission, 
including analyses conducted by MANE-VU and Delaware's determinations 
based on those analyses, Delaware's assessment of progress made since 
the first implementation period in reducing emissions of visibility 
impairing pollutants, and the visibility improvement progress at the 
nearby Class I Area. This rulemaking also contains EPA's evaluation of 
Delaware's submission against the requirements of the CAA and RHR for 
the second implementation period of the regional haze program.

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

[[Page 67028]]

mandatory Class I Area located within the State and in each mandatory 
Class I 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.
    Delaware does not have a Class I Area located within its borders, 
but has been identified as influencing the visibility impairment of the 
Brigantine Wilderness Class I Area, located in the State of New Jersey. 
For the second implementation period, MANE-VU performed technical 
analyses \31\ to help assess source and State-level contributions to 
visibility impairment and the need for interstate consultation. MANE-VU 
used the results of these analyses to determine which States' emissions 
``have a high likelihood of affecting visibility in MANE-VU's Class I 
Areas.'' \32\ Similar to metrics used in the first implementation 
period,\33\ MANE-VU used a greater than 2 percent of sulfate plus 
nitrate emissions contribution criteria to determine whether emissions 
from individual jurisdictions within the region affected visibility in 
any Class I Areas. The MANE-VU analyses for the second implementation 
period used a combination of data analysis techniques, including 
emissions data, distance from Class I Areas, wind trajectories, and 
California Puff Model (CALPUFF) dispersion modeling. Although many of 
the analyses focused only on SO2 emissions and resultant 
particulate sulfate contributions to visibility impairment, some also 
incorporated NOX emissions to estimate particulate nitrate 
contributions.
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    \31\ The contribution assessment methodologies for MANE-VU Class 
I Areas are summarized in appendix 1-1 of the DE Regional Haze SIP 
submission, ``Selection of States for MANE-VU Regional Haze 
Consultation (2018)'' in the docket.
    \32\ Id.
    \33\ See docket EPA-R03-OAR-2011-0289 for MANE-VU supporting 
materials.
---------------------------------------------------------------------------

    One MANE-VU analysis used for contribution assessment was CALPUFF 
air dispersion modeling. The CALPUFF model was used to estimate sulfate 
and nitrate formation and transport in MANE-VU and nearby regions 
originating from large electric generating unit (EGU) point sources and 
other large industrial and institutional sources in the eastern and 
central United States. Information from an initial round of CALPUFF 
modeling was collated for the 444 EGUs that were determined to warrant 
further scrutiny based on their emissions of SO2 and 
NOX. The list of EGUs was based on an enhanced ``Q/d'' 
analysis \34\ that considered recent SO2 emissions in the 
eastern United States and an analysis that adjusted previous 2002 MANE-
VU CALPUFF modeling by applying a ratio of 2011 to 2002 SO2 
emissions. This list of sources was then enhanced by including the top 
five SO2 and NOX emission sources for 2011 for 
each State included in the modeling domain. A total of 311 EGU stacks 
(as opposed to individual units) were included in the CALPUFF modeling 
analysis. Initial information was also collected on the 50 industrial 
and institutional sources that, according to 2011 Q/d analysis, 
contributed the most to visibility impact in each Class I Area. The 
ultimate CALPUFF modeling run included a total of 311 EGU stacks and 82 
industrial facilities. The summary report for the CALPUFF modeling 
included the top 10 most impacting EGUs and the top five most impacting 
industrial/institutional sources for each Class I Area and compiled 
those results into a ranked list of the most impacting EGUs and 
industrial sources at MANE-VU Class I Areas.\35\
---------------------------------------------------------------------------

    \34\ ``Q/d'' is emissions (Q) in tons per year, typically of one 
or a combination of visibility-impairing pollutants, divided by 
distance to a class I area (d) in kilometers. The resulting ratio is 
commonly used as a metric to assess a source's potential visibility 
impacts on a particular class I area.
    \35\ See tables 34 and 35 of appendix 8-5 of the DE 2022 
Regional haze SIP submission, ``2016 MANE-VU CALPUFF Modeling 
Report'' in the docket.
---------------------------------------------------------------------------

    The second MANE-VU contribution analysis used a meteorologically 
weighted Q/d calculation to assess States' contributions to visibility 
impairment at MANE-VU Class I Areas.\36\ This analysis focused 
predominantly on SO2 emissions and used cumulative 
SO2 emissions from a source and a State for the variable 
``Q,'' and the distance of the source or State to the IMPROVE monitor 
receptor at a Class I Area as ``d.'' The result is then multiplied by a 
constant (Ci), which is determined based on the prevailing 
wind patterns. MANE-VU selected a meteorologically weighted Q/d 
analysis as an inexpensive initial screening tool that could easily be 
repeated to determine which States, sectors, or sources have a larger 
relative impact and warrant further analysis. MANE-VU's analysis 
estimated SO2 emission contribution from Delaware sources of 
less than 2% of visibility impairment for all seven MANE-VU Class I 
Areas. Although MANE-VU did not originally estimate nitrate impacts, 
the MANE-VU Q/d analysis was subsequently extended to account for 
nitrate contributions from NOX emissions and to approximate 
the nitrate impacts from area and mobile sources. MANE-VU therefore 
developed a ratio of nitrate to sulfate impacts based on the previously 
described CALPUFF modeling and applied those to the sulfate Q/d results 
in order to derive nitrate contribution estimates. Several States did 
not have CALPUFF nitrate to sulfate ratio results, however, because 
there were no point sources modeled with CALPUFF.
---------------------------------------------------------------------------

    \36\ See appendix 8-2, ``Contribution to Regional Haze in the 
Northeast and Mid-Atlantic United States: Preliminary Update Through 
2007.''
---------------------------------------------------------------------------

    To develop a final set of contribution estimates, MANE-VU weighted 
the results from both the Q/d and CALPUFF analyses. The MANE-VU mass-
weighted sulfate and nitrate contribution results were reported for the 
MANE-VU Class I Areas (the Q/d summary report included results for 
several non-MANE-VU areas as well). If a State's contribution to 
sulfate and nitrate concentrations at a particular Class I Area was 2 
percent or greater, MANE-VU regarded that State as contributing to 
visibility impairment in that area. Delaware's highest mass-weighted 
sulfate and nitrate contribution to any Class I Area was 0.6% to the 
Brigantine Wilderness Class I Area. Even with a contribution level 
below 2 percent threshold, Delaware agreed to participate in the 
consultation process, as part of the MANE-VU RPO.
    As explained above, 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 at 35721 
(July 1, 1999), 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. Consistent with 
these requirements, the 2019 Guidance makes it clear that ``all types 
of anthropogenic sources are to be included in the determination'' of 
whether a State's emissions are reasonably anticipated to result in any 
visibility impairment. 2019 Guidance at 8.
    First, as an aside, the screening analyses on which MANE-VU relied 
are useful for certain purposes. MANE-VU used information from its 
technical analysis to rank the largest contributing States to sulfate 
and nitrate impairment in five Class I Areas within MANE-VU States and 
three additional, nearby Class I Areas.\37\ The rankings were used to

[[Page 67029]]

determine upwind States that were deemed important to include in state-
to-state consultation (based on an identified impact screening 
threshold). Additionally, large individual source impacts were used to 
target MANE-VU control analysis ``Asks'' \38\ of States and sources 
both within and upwind of MANE-VU.\39\ EPA finds the nature of the 
analyses generally appropriate to support decisions on States with 
which to consult. However, we have cautioned that source selection 
methodologies that target the largest regional contributors to 
visibility impairment across multiple States may not be reasonable for 
a particular State if it results in few or no sources being selected 
for subsequent analysis. 2021 Clarifications Memo at 3. Delaware has 
participated in the MANE-VU visibility analysis and has provided 
information in its SIP submission on the magnitude of visibility 
impacts from certain Delaware emission sources, specifically the Indian 
River Generating Station and the Edge Moor Energy Center (EMEC), on 
nearby Class I Areas.
---------------------------------------------------------------------------

    \37\ The Class I Areas analyzed were Acadia National Park in 
Maine, Brigantine Wilderness in New Jersey, Great Gulf Wilderness in 
New Hampshire, Lye Brook Wilderness in Vermont, Moosehorn Wilderness 
in Maine, Shenandoah National Park in Virginia, James River Face 
Wilderness in Virginia, and Dolly Sods/Otter Creek Wildernesses in 
West Virginia.
    \38\ As explained more fully in section IV.E.a, of this document 
MANE-VU refers to each of the components of its overall strategy as 
an ``Ask'' of its member states.
    \39\ The MANE-VU consultation report (appendix D) explains that 
``[t]he objective of this technical work was to identify states and 
sources from which MANE-VU will pursue further analysis. This 
screening was intended to identify which states to invite to 
consultation, not a definitive list of which states are 
contributing.''
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    With regard to the analysis and determinations regarding Delaware's 
contribution to visibility impairment at out-of-state Class I Areas, 
the MANE-VU technical work focuses on the magnitude of visibility 
impacts from certain Delaware emissions on its Class I Area and other 
nearby Class I Areas. However, the analyses did not account for all 
emissions and all components of visibility impairment (e.g., primary PM 
emissions, and impairment from fine PM, elemental carbon, and organic 
carbon). In addition, Q/d analyses with a relatively simplistic 
accounting for wind trajectories and CALPUFF applied to a very limited 
set of EGUs, and major industrial sources of SO2 and 
NOX are not scientifically rigorous tools capable of 
evaluating contribution to visibility impairment from all emissions in 
a State. We again clarify that each State is obligated under the CAA 
and RHR to address regional haze visibility impairment resulting from 
emissions from within the State, irrespective of whether another 
State's contribution is greater. See 2021 Clarifications Memo at 3. 
Additionally, we note that the 2 percent or greater sulfate-plus-
nitrate threshold used to determine whether Delaware's emissions 
contribute to visibility impairment at a particular Class I Area may be 
higher than what EPA believes is an ``extremely low triggering 
threshold'' intended by the statute and regulations. In sum, based on 
the information provided, it is clear that emissions from Delaware 
contribute to visibility impairment at out-of-state Class I Areas. 
However, due to the low triggering threshold implied by the Rule and 
the lack of rigorous modeling analyses, we do not necessarily agree 
with the level of the State's 2% contribution threshold.
    Delaware determined that sources and emissions within the State 
contribute to visibility impairment at three out-of-state Class I 
Areas.\40\ Furthermore, the State took part in the emission control 
strategy consultation process as a member of MANE-VU pursuant to the 
regulatory requirements. As part of that process, MANE-VU developed a 
set of emissions reduction measures identified as being necessary to 
make reasonable progress in the five MANE-VU Class I Areas. This 
strategy consists of six ``Asks'' for States within MANE-VU and five 
``Asks'' for States outside the region that were found to impact 
visibility at Class I Areas within MANE-VU.\41\ Delaware's submission 
discusses each of the ``Asks'' and explains why or why not each is 
applicable and how it has complied with the relevant components of the 
emissions control strategy MANE-VU has laid out for its States. 
Delaware worked with MANE-VU to determine potential reasonable measures 
that could be implemented by 2028, considering the cost of compliance, 
the time necessary for compliance, the energy and non-air quality 
environmental impacts, and the remaining useful life of any potentially 
affected sources. As discussed in further detail below, the EPA is 
proposing to find that Delaware has submitted a regional haze plan that 
meets the requirements of 40 CFR 51.308(f)(2) related to the 
development of a long-term strategy. Although we have concerns 
regarding some aspects of MANE-VU's technical analyses supporting 
States' contribution determinations, we propose to find that Delaware 
has nevertheless satisfied the applicable regulatory requirements for 
making reasonable progress towards natural visibility conditions in 
Class I Areas that may be affected by emissions from the State.
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    \40\ Brigantine in NJ, James River Face in WV and Shenandoah 
National Park in VA.
    \41\ See appendix 9-1 of the DE Regional Haze SIP submittal, 
``Statement of the Mid-Atlantic/Northeast Visibility Union (MANE-VU) 
Concerning a Course of Action within MANE-VU toward Assuring 
Reasonable Progress for the Second Regional Haze Implementation 
Period (2018-2028), (August 2017).''
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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).
    Delaware does not have any Class I Area within its borders 
therefore, Sec.  51.308(f)(1) and its requirements do not apply.\42\
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    \42\ While Delaware noted that it was not required to comply 
with 40 CFR 51.308(f)(1), elsewhere in its SIP submission (section 
8.10), Delaware included a visibility metric graph of a nearby Class 
I area, which was taken from a MANE-VU report referenced in their 
SIP submittal, titled ``Mid-Atlantic/Northeast U.S. Visibility Data 
2004-2019 (2nd RH SIP Metrics) (May 1, 2020 revisions) (January 21, 
2021 revision).''
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E. Long-Term Strategy for Regional Haze

a. Delaware's Response to the Six MANE-VU Asks
    Each State having a Class I Area within its borders or emissions 
that may affect visibility in a Class I Area must develop a long-term 
strategy for making reasonable progress towards the national visibility 
goal. CAA 169A(b)(2)(B). As explained in the Background section of this 
rulemaking, reasonable progress is achieved when all States 
contributing to visibility impairment in a Class I Area are 
implementing the measures determined--through application of the four 
statutory factors to sources of visibility impairing pollutants--to be 
necessary to make reasonable progress. 40 CFR 51.308(f)(2)(i). Each 
State's long-term strategy must include the enforceable emission 
limitations,

[[Page 67030]]

compliance schedules, and other measures that are necessary to make 
reasonable progress. 40 CFR 51.308(f)(2). All new (i.e., additional) 
measures that are the outcome of four-factor analyses are necessary to 
make reasonable progress and must be in the long-term strategy. If the 
outcome of a four-factor analysis and other measures necessary to make 
reasonable progress is that no new measures are reasonable for a 
source, that source's existing measures are necessary to make 
reasonable progress, unless the State can demonstrate that the source 
will continue to implement those measures and will not increase its 
emission rate. Existing measures that are necessary to make reasonable 
progress must also be in the long-term strategy. In developing its 
long-term strategies, a State must also consider the five additional 
factors in 40 CFR 51.308(f)(2)(iv). As part of its reasonable progress 
determinations, the State must describe the criteria used to determine 
which sources or group of sources were evaluated (i.e., subjected to 
four-factor analysis) for the second implementation period and how the 
four factors were taken into consideration in selecting the emission 
reduction measures for inclusion in the long-term strategy. 40 CFR 
51.308(f)(2)(iii).
    The following section summarizes how Delaware's SIP submission 
addressed the requirements of 40 CFR 51.308(f)(2)(i). Specifically, it 
describes MANE-VU's development of the six Asks and how Delaware 
addressed each one.
    States may rely on technical information developed by the RPOs of 
which they are members to select sources for four-factor analysis and 
to conduct that analysis, as well as to satisfy the documentation 
requirements under 40 CFR 51.308(f). Where an RPO has performed source 
selection and/or four-factor analyses (or considered the five 
additional factors in 40 CFR 51.308(f)(2)(iv)) for its member States, 
those States may rely on the RPO's analyses for the purpose of 
satisfying the requirements of 40 CFR 51.308(f)(2)(i) so long as the 
States have a reasonable basis to do so and all State participants in 
the RPO process have approved the technical analyses. 40 CFR 
51.308(f)(3)(iii). States may also satisfy the requirement of 40 CFR 
51.308(f)(2)(ii) to engage in interstate consultation with other States 
that have emissions that are reasonably anticipated to contribute to 
visibility impairment in a given Class I Area under the auspices of 
intra- and inter-RPO engagement.
    Delaware is a member of the MANE-VU RPO and participated in the 
RPO's regional approach to developing a strategy for making reasonable 
progress towards the national visibility goal in the MANE-VU Class I 
Areas. MANE-VU's strategy includes a combination of: (1) measures for 
certain source sectors and groups of sectors that the RPO determined 
were reasonable for States to pursue, and (2) a request for member 
States to conduct four-factor analyses for individual sources that it 
identified as contributing to visibility impairment. MANE-VU refers to 
each of the components of its overall strategy as an Ask of its member 
States. On August 25, 2017, the Executive Director of MANE-VU, on 
behalf of the MANE-VU States and Tribal nations, signed a statement 
that identifies six emission reduction measures that comprise the 
``Asks'' for the second implementation period.\43\ The ``Asks'' were 
``designed to identify reasonable emission reduction strategies that 
must be addressed by the states and tribal nations of MANE-VU through 
their regional haze SIP updates.'' \44\ The statement explains that 
``[i]f any State cannot agree with or complete a Class I State's Asks, 
the State must describe the actions taken to resolve the disagreement 
in the Regional Haze SIP.'' \45\
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    \43\ See appendix 9-1 of the DE Regional Haze SIP submittal, 
``Statement of the Mid-Atlantic/Northeast Visibility Union (MANE-VU) 
Concerning a Course of Action within MANE-VU toward Assuring 
Reasonable Progress for the Second Regional Haze Implementation 
Period (2018-2028), (August 2017).''
    \44\ Id.
    \45\ Id.
---------------------------------------------------------------------------

    MANE-VU's recommendations as to the appropriate control measures 
were based on technical analyses documented in the RPO's reports and 
included as appendices to or referenced in Delaware's regional haze SIP 
submission. One of the initial steps of MANE-VU's technical analysis 
was to determine which visibility-impairing pollutants should be the 
focus of its efforts for the second implementation period. In the first 
implementation period, MANE-VU determined that sulfates were the most 
significant visibility impairing pollutant at the region's Class I 
Areas. To determine the impact of certain pollutants on visibility at 
Class I Areas for the purpose of second implementation period planning, 
MANE-VU conducted an analysis comparing the pollutant contribution on 
the clearest and most impaired days in the baseline period (2000-2004) 
to the most recent period (2012-2016) \46\ at MANE-VU and nearby Class 
I Areas. MANE-VU found that while SO2 emissions were 
decreasing and visibility was improving, sulfates still made up the 
most significant contribution to visibility impairment at MANE-VU and 
nearby Class I Areas. According to the analysis, NOX 
emissions have begun to play a more significant role in visibility 
impacts in recent years, especially at the Brigantine Wilderness Class 
I Area. The technical analyses used by Delaware are included in their 
submission and are as follows:
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    \46\ The period of 2012-2016 was the most recent period for 
which data was available at the time of analysis.

 The Nature of the Fine Particle and Regional Haze Air Quality 
Problems in the MANE-VU Region: A Conceptual description (NESCAUM, 
November 2006, Revised August 2010 and July 2012) (Appendix 8-1)
 Contributions to Regional Haze in the Northeast and Mid-
Atlantic United States: Preliminary Update Through 2007 (NESCAUM, March 
2012) (Appendix 8-2)
 MANE-VU Updated Q/d*C Contribution Assessment. (MANE-VU, April 
2016) (Appendix 8-3)
 2016 Updates to the Assessment of Reasonable Progress in MANE-
VU Class I Areas (MARAMA, January 2016) (Appendix 8-4)
 2016 MANE-VU Source Contribution Modeling Report--CALPUFF 
Modeling of Large Electrical Generating Units and Industrial Sources 
(MANE-VU, April 2017) (Appendix 8-5)
 Regional Haze Metrics Trends and HYSPLIT Trajectory Analysis. 
(MANE-VU, May 2017) (Appendix 8-6)
 Permit Cancellation Documents for McKee Run Generating 
Station, City of Dover. (DNREC, November 2021) (Appendix 8-7)
 Recommendation on Approaches to Selecting the 20% Most 
Impaired Days. (MANE-VU, March 2017) (Appendix 8-8)
 Analysis of Speciation Trends Network Data Measured at the 
State of Delaware, Philip K. Hopke and Eugene Kim, Center for Air 
Resources Engineering and Science Clarkson University. (January 2005) 
(Appendix 8-9)

    To support development of the ``Asks,'' MANE-VU gathered 
information on each of the four statutory factors for six source 
sectors it determined, based on an examination of annual emission 
inventories, ``had emissions that were reasonabl[y] anticipated to 
contribute to visibility

[[Page 67031]]

degradation in MANE-VU:'' electric generating units (EGUs), industrial/
commercial/institutional boilers (ICI boilers), cement kilns, heating 
oil, residential wood combustion, and outdoor wood combustion.\47\ 
MANE-VU also collected data on individual sources within the EGU, ICI 
boiler, and cement kiln sectors.\48\ Information for the six sectors 
included explanations of technically feasible control options for 
SO2 or NOX, illustrative cost-effectiveness 
estimates for a range of model units and control options, sector-wide 
cost considerations, potential time frames for compliance with control 
options, potential energy and non-air-quality environmental impacts of 
certain control options, and how the remaining useful lives of sources 
might be considered in a control analysis.\49\ Source-specific data 
included SO2 emissions \50\ and existing controls \51\ for 
certain existing EGUs, ICI boilers, and cement kilns. MANE-VU 
considered this information on the four factors as well as the analyses 
developed by the RPO's Technical Support Committee when it determined 
specific emission reduction measures that were found to be reasonable 
for certain sources within two of the sectors it had examined--EGUs and 
ICI boilers. The ``Asks'' were based on this analysis and looked to 
either optimize the use of existing controls, have States conduct 
further analysis on EGU or ICI boilers with considerable visibility 
impacts, implement low sulfur fuel standards, or lock-in lower emission 
rates.
---------------------------------------------------------------------------

    \47\ See MANE-VU's ``Four Factor Data Collection'' Memo at 1, 
March 30, 2017, available at otcair.org/MANEVU/Upload/Publication/Reports/Four-Factor%20Data%20Collection%20Memo%20-%20170314.pdf. The 
six sectors were identified in the first implementation period 
pursuant to MANE-VU's contribution assessment; MANE-VU subsequently 
updated its information on these sectors for the second 
implementation period.
    \48\ See appendix 8-4 ``2016 Updates to the Assessment of 
Reasonable Progress for Regional Haze in MANE-VU Class I Areas, 
January 31, 2016.''
    \49\ Id.
    \50\ See docket document, ``MANE-VU's ``Four Factor Data 
Collection Memo'' March 30, 2017, table 1 contains 2011 
SO2 data from specific sources.
    \51\ The ``Status of the Top 167 EGUs that Contributed to 
Visibility Impairment at MANE-VU Class I Areas during the 2008 
Regional Haze Planning Period'' July 25, 2016, reviews the existing 
and soon to be installed, at the time of the report, emission 
controls at individual EGU sources that were a part of the MANE-VU 
Ask from the first implementation period. Available at: otcair.org/MANEVU/Upload/Publication/Reports/Status%20of%20the%20Top%20167%20Stacks%20from%20the%202008%20MANE-VU%20Ask.pdf.
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    MANE-VU Ask 1 is ``ensure the most effective use of control 
technologies on a year-round basis to consistently minimize emissions 
of haze precursors or obtain equivalent alternative emission 
reductions'' at EGUs with a nameplate capacity larger than or equal to 
25 megawatts (MW) with already installed NOX and/or 
SO2 controls.\52\
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    \52\ See appendix 8-12 ``MANE-VU Regional Haze Consultation 
Report.''
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    To address Ask 1, first, Delaware indicated that all the units that 
burn fuel oil are covered year-round by a Delaware low sulfur fuel 
regulation at Title 7 Delaware Administrative Code (7 DE Admin Code) 
1108,\53\ that was approved into the SIP on July 11, 2022 (87 FR 
41074). Delaware's SIP-approved low sulfur fuel regulation reduces the 
SIP-approved maximum allowable sulfur content limit for distillate 
fuels from 3,000 ppm to 15 ppm, for residual fuel from 1% to 0.5% by 
weight, and for any other fuel, the sulfur content would remain at 1.0% 
by weight. Based on that, the State asserted that it met the request to 
ensure SO2 controls year-round under Ask 1.
---------------------------------------------------------------------------

    \53\ 7 DE Admin Code 1108 ``Sulfur Dioxide Emissions from Fuel 
Burning Equipment.'' See 87 FR 41074, July 11, 2022.
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    Delaware then focused its efforts on the control of NOX 
emissions and identified 10 EGUs with nameplate capacity larger than or 
equal to 25 MW, of which four had permits that did not require the use 
of NOX controls year-round on some of their units. The four 
sources are Christiana Energy Center (ChEC), Edge Moor Energy Center 
(EMEC), Garrison Energy Center (GEC), and Hay Road Energy Center 
(HREC), which are all owned by Calpine Mid-Atlantic Generation, LLC 
(Calpine). To meet the Ask, Delaware requested the EGUs to perform 
four-factor analyses on the pertinent units to determine if year-round 
NOX controls are feasible. Details of the EGUs' four-factor 
analyses with regard to Ask 1 can be found in a technical support 
document (TSD) of this proposed rulemaking action; specifically, it 
describes how Delaware addressed each Ask.
    Based on the four-factor analyses performed by the sources to 
evaluate adding or expanding NOX controls year-round, only 
one of the sources, ChEC, concluded that it was feasible to operate the 
existing controls for an additional period throughout the year. Based 
upon that conclusion and in order to meet the Ask, Delaware updated 
applicable permits in May 2021 to reflect the new measures, and 
submitted the redacted permits for incorporation into the SIP. 
Additional details can be found in the TSD (section III-a.-1. at 8). 
Delaware therefore concluded that it met Ask 1.
    MANE-VU Ask 2 requests that States ``perform a four-factor analysis 
for reasonable installation or upgrade to emissions controls'' for 
specified sources. MANE-VU developed its Ask 2 list of sources for 
analysis by performing modeling and identifying facilities with the 
potential for 3.0 inverse megameters (Mm-1) or greater 
impacts on visibility at any Class I Area in the MANE-VU region.\54\ 
Delaware explained that it has no facilities that were modeled by MANE-
VU to impact visibility at any Class I Area by 3.0 Mm-1 or 
more and concluded that it is currently meeting Ask 2. While Delaware 
did not select sources that fell under MANE-VU's 3.0 Mm-1 
threshold for four-factor analysis, it did provide supplemental 
information about a large source that was identified by commenters and 
explanation supporting its decision not to request the facility to 
evaluate measures for reasonable progress because the facility is 
effectively controlled.
---------------------------------------------------------------------------

    \54\ See appendix 8-12 ``MANE-VU Regional Haze Consultation 
Report.''
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    Specifically, commenters asserted that Delaware should have 
selected the Delaware City Refinery Company, LLC (DCRC) for a four-
factor analysis of possible controls. In its SIP submission, Delaware 
explained the reasons it did not conduct a four-factor analysis for 
DCRC. First, based on MANE-VU's modeling results, DCRC showed that its 
impact on visibility impairment was low; \55\ second, Delaware relied 
on the threshold that was agreed to by all MANE-VU States, including 
those that have Class I Areas within their boundaries; and third, the 
source is well controlled for SO2 and NOX through 
existing State regulations and several consent decrees. Section 8.13.2 
of the SIP submission contains a detailed description of controls 
required for SO2 and NOX emissions, pursuant to 
two Federal consent decrees, an agreement governing the acquisition and 
operation of the facility, and State and Federal regulations that DCRC 
is subject to.\56\ More details about Delaware's response to Ask 2 can 
be found in the TSD of this proposed rulemaking action.
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    \55\ The Q/d for this facility, as calculated by MANE-VU, ranged 
from 0.36-3.25 for the eight Class I Areas in the MANE-VU analysis, 
with Brigantine Wilderness Area being at the top of this range; see 
docket documents, ``Delaware Response to EPA Regional Haze Info 
Request 11-3-23'' and ``Attachment E--QDCPointOnly--
Delaware1.xlsx''. In addition, this facility was not one of the 82 
Industrial, Commercial, and Institutional sources identified by 
MANE-VU's CALPUFF modeling as having emissions similar in magnitude 
to the EGUs modeled in this exercise or that are close enough to a 
Class I area that they would have the potential for visibility 
impacts.
    \56\ See the DE Regional Haze SIP submittal at 91.
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    MANE-VU Ask 3 requests that ``each MANE-VU State that has not yet 
fully adopted an ultra-low fuel oil standard as

[[Page 67032]]

requested by MANE-VU in 2007'', to ``pursue this standard as 
expeditiously as possible and before 2028, depending on supply 
availability.'' The Ask includes percent by weight standards for #2 
distillate oil (0.0015% sulfur by weight or 15 parts per million 
(ppm)), #4 residual oil (0.25-0.5% sulfur by weight), and #6 residual 
oil (0.3-0.5% sulfur by weight). Delaware explained that, in 2013, it 
adopted the 7 DE Admin Code 1108 low-sulfur fuel regulation \57\ which 
went into effect on July 1, 2016. Delaware therefore concluded that it 
is meeting Ask 3. Additional details about Delaware's response to Ask 3 
can be found in the TSD of this proposed rulemaking action at 24.
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    \57\ See 87 FR 41074 (July 11, 2022).
---------------------------------------------------------------------------

    MANE-VU Ask 4 requests States to ``pursue updating permits, 
enforceable agreements, and/or rules to ``lock in'' lower emissions 
rates for SO2, NOX and PM'' at emission sources 
larger than 250 million British Thermal Units (MMBtu) per hour heat 
input that have switched to lower emitting fuels.\58\ Based on 
Delaware's SIP submission, two EGUs fell under Ask 4. The first source 
is Calpine's EMEC, which had switched operations to lower emitting 
fuels and had its permits updated to lock in lower emission rates for 
SO2, NOX and PM. A second source, City of Dover 
McKee Run Generating Station, had its permits cancelled in November 
2021.\59\ Based on these updates, Delaware concluded it is meeting Ask 
4. More details about Delaware's response to Ask 4 are included in the 
TSD of this proposed rulemaking action.
---------------------------------------------------------------------------

    \58\ See appendix 8-12 ``MANE-VU Regional Haze Consultation 
Report.''
    \59\ See appendix 8-7 ``McKee Run Permit Cancellation Letter.''
---------------------------------------------------------------------------

    MANE-VU Ask 5 requests that MANE-VU States ``where emission rules 
have not been adopted, control NOX emissions for peaking 
combustion turbines that have the potential to operate on high electric 
demand days (HEDD)'' by either: (a) striving to meet NOX 
emissions standards specified in the Ask for turbines that run on 
natural gas and fuel oil, (b) performing a four-factor analysis for 
reasonable installation of or upgrade to emission controls, or (c) 
obtaining equivalent alternative emission reductions on HEDD.\60\ The 
Ask requests States to strive for NOX emission standards of 
no greater than 25 ppm for natural gas and 42 ppm for fuel oil, or at a 
minimum, NOX emissions standards of no greater than 42 ppm 
for natural gas and 96 ppm for fuel oil.
---------------------------------------------------------------------------

    \60\ See appendix 8-12 ``MANE-VU Regional Haze Consultation 
Report.''
---------------------------------------------------------------------------

    For Ask 5, Delaware identified seven sources with units affected by 
HEDD,\61\ and two of the seven sources met the emission limits provided 
in option (a). Delaware requested that each of the remaining five 
sources perform four-factor analyses as stated in option (b) of the Ask 
because their current Title V permits do not meet the NOX 
standards from option (a).\62\ Based on the four-factor analyses 
conducted by the five sources to evaluate potential control options for 
HEDD units, three of them found it economically feasible to operate 
existing controls during two additional months adjacent to the ozone 
season, for which Delaware updated their Title V permits accordingly 
and submitted the permits for incorporation into the SIP. For the 
remaining two sources, Delaware reviewed the facilities' estimates of 
compliance costs \63\ of $192,000/ton of NOX removed for one 
and $334,897/ton of NOX removed for the other to upgrade 
their respective units,\64\ and Delaware concluded that it was not an 
economically feasible option for these sources to upgrade their 
existing control given the limited operational time and low level of 
reported annual NOX emissions within the State as shown on 
table 10-5 of the SIP submittal. In addition, Delaware evaluated 
various potential new control options for the five sources but found 
that these were neither economically nor technically feasible. Because 
Delaware conducted four-factor analyses on the selected sources, 
Delaware concluded it has satisfied Ask 5 through option (b). More 
details about Delaware's EGUs four-factor analyses with regards to Ask 
5 can be found in the TSD of this proposed rulemaking action.
---------------------------------------------------------------------------

    \61\ See table 10-4 (Delaware Units Affected by HEDD ``Ask #5'') 
of the DE Regional Haze SIP submittal at 110.
    \62\ See table 10-5 (Average Operating Hours and NOX 
Emissions for Units Under ``Ask #5'') of the DE Regional Haze SIP 
submittal at 111.
    \63\ Per the DE Regional Haze SIP submittal section 10.5, costs 
were based on similar projects in other states for the one facility, 
and vendor quotes and EPA's Air Pollution Control Cost Manual for 
the other facility.
    \64\ See section 10.5 of the DE Regional Haze SIP submittal.
---------------------------------------------------------------------------

    MANE-VU Ask 6, requests that ``each State should consider and 
report in their SIP measures or programs to: (a) decrease energy demand 
through the use of energy efficiency and (b) increase the use within 
their State of Combined Heat and Power (CHP) and other clean 
Distributed Generation technologies including fuel cells, wind and 
solar.'' \65\ Delaware stated that it implemented a number of measures 
with regard to this Ask. Some of these include the Energy Task Force 
Executive Order signed on April 26, 2002, the Delaware Energy 
Efficiency Advisory Council (EEAC), the 2005 Renewable Energy Portfolio 
Standards Act which is the basis for Delaware's renewable energy 
portfolio standards (RPS), and the Regional Greenhouse Gas Initiative 
(RGGI), to name a few. Based on these measures, Delaware concluded it 
is meeting Ask 6. Additional details about Delaware's response to Ask 6 
can be found in the TSD of this proposed rulemaking action.
---------------------------------------------------------------------------

    \65\ See appendix 8-12 ``MANE-VU Regional Haze Consultation 
Report.''
---------------------------------------------------------------------------

b. EPA's Evaluation of Delaware's Response to the Six MANE-VU Asks and 
Compliance With 40 CFR 51.308(f)(2)(i)
    EPA is proposing to find that Delaware has satisfied the 
requirements of 40 CFR 51.308(f)(2)(i) related to evaluating sources 
and determining the emission reduction measures that are necessary to 
make reasonable progress by considering the four statutory factors.
    Through Ask 1, MANE-VU instructed States to ``ensure the most 
effective use of control technologies on a year-round basis to 
consistently minimize emissions of haze precursors or obtain equivalent 
alternative emission reductions'' at EGUs with a nameplate capacity 
larger than or equal to 25 megawatts (MW) with already installed 
NOX and/or SO2 controls.\66\
---------------------------------------------------------------------------

    \66\ Id.
---------------------------------------------------------------------------

    EPA reviewed and evaluated Delaware's response to the four-factor 
analyses on the four sources with permits that did not require 
NOX controls year-round on some of their units and found 
that the State agreed with Calpine's conclusions for each of the 
sources. For ChEC and EMEC, Delaware agreed that it is not economically 
feasible to operate their NOX existing controls year-round 
because the units' operation and, hence, NOX emissions are 
both limited. On the other hand, for GEC and HREC, Delaware agreed that 
it is not technically feasible to retrofit the sources' NOX 
existing controls to operate year-round due to the same conclusion that 
operation and NOX emissions are limited. To support their 
conclusion, on table 10-2 of the SIP submittal, Delaware included the 
annual average operating hours and NOX emissions of the 
sources for a five-year period, which demonstrate the generally limited 
operation and the significantly low NOX emissions in recent 
years (i.e., the tons of NOX emitted per unit per year 
ranging from less than two to less than 150).

[[Page 67033]]

    EPA agrees with Delaware that it is not reasonable to upgrade any 
of the sources' NOX existing controls due to the extremely 
low emission reductions that would have been achieved, and that the 
costs of compliance, as demonstrated through the four-factor analyses, 
are not justified by the low amount of NOX emission 
reductions that the sources would achieve if these were reconfigured. 
More information on the amount of NOX emitted from these 
units can be found in the TSD at 32-33.
    EPA also reviewed and evaluated the State's selection and 
modification of the applicable EGUs' title V permits to incorporate the 
regional haze requirements of the second planning period. To meet Ask 
1, DNREC updated ChEC, EMEC, and HREC's title V permits after 
conducting four-factor analyses. For ChEC, DNREC added the 88 ppm 
NOX emission limit during April and October. For EMEC and 
HREC, DNREC added language requiring the facilities to operate and 
maintain their existing NOX control systems in accordance 
with Calpine's maintenance protocol. Based on the above, EPA thus 
agrees with Delaware's conclusions and proposes to find that Delaware 
reasonably satisfied Ask 1.
    For Ask 2, MANE-VU requested that States ``perform a four-factor 
analysis for reasonable installation or upgrade to emissions controls'' 
for specified sources. MANE-VU developed its Ask 2 list of sources for 
analysis by performing modeling and identifying facilities with the 
potential for 3.0 inverse megameters (Mm-1) or greater 
impacts on visibility at any Class I Area in the MANE-VU region.\67\
---------------------------------------------------------------------------

    \67\ See appendix 8-12 ``MANE-VU Regional Haze Consultation 
Report.''
---------------------------------------------------------------------------

    As an initial matter, EPA does not necessarily agree that MANE-VU 
3.0 Mm-1 visibility impact is a reasonable threshold for 
source selection. The RHR recognizes that, due to the nature of 
regional haze visibility impairment, numerous and sometimes relatively 
small sources may need to be selected and evaluated for control 
measures in order to make reasonable progress. See 2021 Clarifications 
Memo at 4. As explained in the 2021 Clarifications Memo, while states 
have discretion to choose any source selection threshold that is 
reasonable, ``[a] state that relies on a visibility (or proxy for 
visibility impact) threshold to select sources for four-factor analysis 
should set the threshold at a level that captures a meaningful portion 
of the State's total contribution to visibility impairment to Class I 
Areas.'' 2021 Memo at 3. In this case, the 3.0 Mm-1 
threshold did not identify sources in Delaware (only 22 across the 
entire MANE-VU region), indicating that it may be unreasonably 
high.\68\
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    \68\ Even though MANE-VU's 3.0 Mm-1 threshold did not 
identify sources in Delaware, two EGU sources were selected for 
CALPUFF modeling and identified as impacting two Class I Areas, 
Shenandoah National Park (SHEN) and James River Face National Park 
(JARI). These sources were the Indian River and the Edge Moor Energy 
Centers, whose highest impacts to these Class I Areas were at 1.7 
Mm\1\ in 2011 and 0.5 Mm-1 in 2015 from Indian River to 
SHEN, 1.1 Mm-1 in 2011 and 0.7 Mm-1 in 2015 
from Indian River to JARI, 0.2 Mm-1 in 2011 and none in 
2015 from Edge Moor to SHEN, and 0.4 Mm-1 in 2011 and 
none in 2015 from Edge Moor to JARI. Nonetheless, their impacts were 
well below the 3.0 Mm-1 threshold during the selected 
base years of 2011 and 2015. See DE Regional Haze SIP submittal at 
75.
---------------------------------------------------------------------------

    However, EPA proposes to find that Delaware reasonably determined 
that it has satisfied Ask 2. As explained above, we do not necessarily 
agree that a 3.0 Mm-1 threshold for selecting sources for 
four-factor analysis results in a set of sources the evaluation of 
which has the potential to meaningfully reduce the State's contribution 
to visibility impairment. MANE-VU's Ask 2 did not identify any source 
in Delaware for a four-factor analysis; however, as part of EPA's 
evaluation, we note that other MANE-VU Asks identified multiple sources 
and sectors for four-factor analyses in Delaware, and Delaware did 
evaluate additional control measures and conducted four-factor analyses 
through other Asks to meet the regional haze requirements for the 
second planning period. Ask 2 is not the only source selection process 
for this State, and thus EPA is basing this proposed finding on the 
State's consideration of the four factors and units and sectors 
analyzed in Asks 1, 3, and 5.
    Ask 3 requests that, for ``each MANE-VU State that has not yet 
fully adopted an ultra-low fuel oil standard as requested by MANE-VU in 
2007'', to ``pursue this standard as expeditiously as possible and 
before 2028, depending on supply availability.'' EPA proposes to find 
that Delaware reasonably relied on MANE-VU's four-factor analysis for a 
low-sulfur fuel oil regulation, which engaged with each of the 
statutory factors and explained how the information supported a 
conclusion that a 15 ppm-sulfur fuel oil standard for fuel oils is 
reasonable. Delaware's ultra-low sulfur fuel oil regulations,\69\ 
which, as previously stated, were approved into Delaware's SIP on July 
11, 2022 (87 FR 41074), are consistent with Ask 3. EPA therefore 
proposes to find that Delaware reasonably determined that it has 
satisfied Ask 3.
---------------------------------------------------------------------------

    \69\ See 7 DE Admin Code 1108 ``Sulfur Dioxide Emissions from 
Fuel Burning Equipment.''
---------------------------------------------------------------------------

    MANE-VU Ask 4 requests that States ``pursue updating permits, 
enforceable agreements, and/or rules to lock-in lower emission rates 
for SO2, NOX, and PM'' at ``EGUs and other large 
point emission sources larger than 250 MMBTU per hour heat input that 
have switched to lower emitting fuels.'' Ask 4 also states that ``the 
permit, enforceable agreement, and/or rule can allow for suspension of 
the lower emission rate during natural gas curtailment.'' Delaware 
concluded that no additional updates were needed to meet Ask 4 because 
the EGU that fell under this Ask, Calpine EMEC, switched operations to 
lower emitting fuels and has already locked into the lower emission 
rates for NOX, SO2, and PM by permits. In 
addition, the McKee Run Generating Station, that fell under this Ask, 
had its permits cancelled on November 12, 2021. Finally, modified units 
in Delaware are required to amend their permits through the New Source 
Review (NSR) process if they plan to switch back to coal or a fuel that 
will increase emissions. A change in fuel, unless already allowed in 
the permit, would generally be a modification,\70\ and Delaware's 
operating permits regulations require that an application to modify the 
permit be submitted prior to the change in fuel.\71\
---------------------------------------------------------------------------

    \70\ See 7 DE Admin Code 1101, defining ``Modification'' means 
any physical change in, or change in the method of operation of, any 
air contaminant source which results in an emission to the 
atmosphere of a new air contaminant or an increase in the emission 
rate to the atmosphere of one or more existing air contaminants. 
Upon modification, an existing source shall become subject to 7 DE 
Admin Code 1120 only with respect to those pollutants which, after 
modification, are either newly emitted, or emitted at an increased 
rate. Routine maintenance, repair and replacement shall not be 
considered a modification. Conversion to coal required for energy 
considerations, as specified in section 113(d)(5) of the 1977 Clean 
Air Act, shall not be considered a modification. The relocation of 
an existing facility shall be considered a modification whenever the 
Department determines it necessary to maintain ambient air quality 
standards. Change in ownership of an existing facility shall not be 
considered a modification. This definition shall not apply to 7 DE 
Admin Code 1125.
    \71\ See 7 DE Admin Code 1101, ``Operating Permits,'' which 
states that ``written notice that the operation of any air 
contaminant source or control device has been approved by the 
Department.''
---------------------------------------------------------------------------

    EPA proposes to find that Delaware reasonably determined it has 
satisfied Ask 4. This is because the permitting and regulatory 
requirements outlined above, including the fact that sources that have 
switched fuel are generally required to revise their permits to reflect 
the change, and because the State rules make any proposed reversion 
difficult

[[Page 67034]]

by requiring permitting and other control analyses, including NSR.
    Ask 5 requested that ``where emission rules have not been 
adopted,'' MANE-VU States ``control NOX emissions for 
peaking combustion turbines that have the potential to operate on 
HEDD'' by meeting at least one of three options: (a) striving to meet 
NOX emissions standards specified in the Ask for turbines 
that run on natural gas and fuel oil, (b) performing a four-factor 
analysis for reasonable installation of or upgrade to emission 
controls, or (c) obtaining equivalent alternative emission reductions 
on HEDD.\72\
---------------------------------------------------------------------------

    \72\ See appendix 8-12 ``MANE-VU Regional Haze Consultation 
Report.''
---------------------------------------------------------------------------

    For Ask 5, EPA reviewed and evaluated Delaware's response to the 
four-factor analyses on the five sources and found that the State 
agreed with Calpine's conclusions for each of the sources. Delaware 
agreed that it is economically and technically infeasible to retrofit 
the sources' existing NOX controls or to add new 
NOX controls to further reduce NOX emissions 
during HEDD, because the units' operation and, hence, NOX 
emissions are both limited. To support their conclusion, on table 10-5 
of the SIP submittal, Delaware included the annual average operating 
hours and NOX emissions of the sources for a five-year 
period, which demonstrate the limited operation and the significantly 
low NOX emissions in recent years (i.e., less than 4.5 tons 
of NOX emitted per unit per year). EPA agrees with Delaware 
that it is not reasonable to upgrade any of the sources' NOX 
existing controls or to install new controls due to the extremely low 
emission reductions that would have been achieved, and that the costs 
of compliance, as demonstrated through the four-factor analyses, are 
not justified by the low amount of NOX emission reductions 
that the sources would achieve if these were reconfigured. More 
information on the extremely low amount of NOX emitted from 
these units with can be found in the TSD at 32-33.
    EPA also reviewed and evaluated the State's selection and 
modification of the applicable EGUs' title V permits to incorporate the 
regional haze requirements of the second planning period. To meet Ask 
5, DNREC updated ChEC, DEC, and WEC's Title V permits after conducting 
four-factor analyses and added the 88 ppm NOX emission limit 
during April and October. Delaware issued the new permits on May 19, 
2021 and included them in appendix 10-2 of its SIP submittal; redacted 
copies of these permits were subsequently resubmitted to EPA with an 
effective date of December 19, 2023 so that the portions relevant to 
compliance with the regional haze requirements of the second planning 
period could be incorporated into the Delaware SIP.\73\ Based on the 
above-mentioned facts, EPA thus agrees with Delaware's conclusions and 
proposes to find that Delaware reasonably determined it has satisfied 
Ask 5.
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    \73\ DNREC public noticed the submission of the three Calpine 
Title V permits to the Delaware SIP on February 4, 2024; these 
permits were substantively identical to those issued by DNREC on May 
21, 2021, and were updated to remove language designating the April 
and October NOX limit as state enforceable only. DNREC 
accepted public comment regarding the submittal of the permits to 
the SIP through March 5, 2024. No public comment was received. DNREC 
submitted the three permits as a supplement to its original Second 
Visibility Plan to EPA on March 7, 2024. On May 28, 2024, DNREC 
provided a clarification of this supplemental SIP submittal that 
specified which provisions of the Title V permits it intended to be 
incorporated by reference into the Delaware SIP. As a result, the 88 
ppm NOX emission limit as extended to April and October 
and related permit conditions will be federally enforceable. These 
permits and their associated public notice and transmittal letters 
are included in the rulemaking docket for this action.
---------------------------------------------------------------------------

    Through Ask 6, MANE-VU requests that ``each State should consider 
and report in their SIP measures or programs to: (a) decrease energy 
demand through the use of energy efficiency, and (b) increase the use 
within their State of Combined Heat and Power (CHP) and other clean 
Distributed Generation technologies including fuel cells, wind, and 
solar.'' \74\ The fact that Delaware has listed its various greenhouse 
gas initiatives and clean energy requirements within the State 
including Executive Order 31--Energy Task Force, energy efficiency 
initiatives such as the EEAC, grants programs, Delaware Energy Code 
Coalition, and CHP Grant Pathway Program, RPS, RGGI, Delaware's Climate 
Change Impact Assessment and a Climate Action Plan, suggests that 
Delaware has in fact reasonably satisfied the Ask. EPA is therefore 
proposing to find that Delaware has reasonably determined it has met 
Ask 6's request to consider and report in its SIP measures or programs 
related to energy efficiency, cogeneration, and other clean distributed 
generation technologies.
---------------------------------------------------------------------------

    \74\ See appendix 8-12 ``MANE-VU Regional Haze Consultation 
Report.''
---------------------------------------------------------------------------

    Based on all of the above, EPA is proposing to find that--based on 
Delaware's participation in the MANE-VU planning process, how it has 
addressed each of the Asks, its supplemental information and 
explanation regarding NOX sources and emissions, and EPA's 
additional assessment of Delaware's emissions and point sources--
Delaware has complied with the requirements of 40 CFR 51.308(f)(2).\75\
---------------------------------------------------------------------------

    \75\ More details about how Delaware met the requirements of 40 
CFR 51.308(f)(2) can be found in the TSD of this rulemaking action.
---------------------------------------------------------------------------

    As explained above, Delaware relied on MANE-VU's technical analyses 
and framework (i.e., the Asks) to select sources and form the basis of 
its long-term strategy. MANE-VU conducted an inventory analysis to 
identify the source sectors that produced the greatest amount of 
SO2 and NOX emissions in 2011; inventory data 
were also projected to 2018. Based on this analysis, MANE-VU identified 
the top-emitting sectors for each of the two pollutants, which for 
SO2 include coal-fired EGUs, industrial boilers, oil-fired 
EGUs, and oil-fired area sources including residential, commercial, and 
industrial sources. Major-emitting sources of NOX include 
on-road vehicles, non-road vehicles, and EGUs. The RPO's documentation 
explains that ``[EGUs] emitting SO2 and NOX and 
industrial point sources emitting SO2 were found to be 
sectors with high emissions that warranted further scrutiny. Mobile 
sources were not considered in this analysis because any ask concerning 
mobile sources would be made to EPA and not during the intra-RPO and 
inter-RPO consultation process among the states and tribes.'' EPA 
proposes to find that Delaware reasonably evaluated the two 
pollutants--SO2 and NOX--that currently drive 
visibility impairment within the MANE-VU region and that it adequately 
explained and supported its decision to focus on these two pollutants 
through its reliance on the MANE-VU technical analyses cited in its 
submission.
    Section 51.308(f)(2)(i) requires States to evaluate and determine 
the emission reduction measures that are necessary to make reasonable 
progress by applying the four statutory factors to sources in a control 
analysis. As explained previously, the MANE-VU Asks are a mix of 
measures for sectors and groups of sources identified as reasonable for 
States to address in their regional haze plans. While MANE-VU 
formulated the Asks to be ``reasonable emission reduction strategies'' 
to control emissions of visibility impairing pollutants, EPA believes 
that Delaware's responses to four of the Asks, in particular, engage 
with the requirement that States determine the emission reduction 
measures that are necessary to make reasonable progress through 
consideration of the four factors. Specifically, MANE-VU Asks 1, 2, 3

[[Page 67035]]

and 5 engage with the requirement that States evaluate and determine 
the emission reduction measures that are necessary to make reasonable 
progress by considering the four statutory factors. EPA is proposing to 
find that Delaware's approach to Asks 1, 2, 3 and 5 is reasonable 
because it demonstrated that the sources and source sectors with 
impacts on visibility either: (1) have reduced their emissions so 
significantly that it is clear a four-factor analysis would not yield 
further reasonable emission reductions, (2) completed four-factor 
analyses and adopted economically feasible controls, or (3) are subject 
to stringent emission control measures. Delaware's SIP-approved control 
measures, emissions inventory \76\ and information provided in response 
to comments \77\ demonstrate that the sources of SO2 and 
NOX within the State that would be expected to contribute to 
visibility impairment have low emissions of NOX and 
SO2, are well controlled, or both. Therefore, it is 
reasonable to assume that selecting additional sources for four-factor 
analysis would not have resulted in additional emission reduction 
measures being determined to be necessary to make reasonable progress 
for the second implementation period. EPA is proposing to incorporate 
the redacted permits submitted on March 7, 2024 into the SIP.
---------------------------------------------------------------------------

    \76\ See appendix 1-1, ``Selection of States for MANE-VU 
Regional Haze Consultation (2018)--Final''.
    \77\ See the ``Response to Comment Memo'' document in the docket 
of this rulemaking action.
---------------------------------------------------------------------------

c. 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.
    Delaware participated in and provided documentation of the MANE-VU 
intra- and inter-RPO consultation processes and addressed the MANE-VU 
Asks by providing information on the measures it has in place that 
satisfy each Ask.78 79 MANE-VU also documented disagreements 
that occurred during consultation. MANE-VU noted in their Consultation 
Report that upwind States expressed concern regarding the analyses the 
RPO utilized for the selection of States for the consultation. MANE-VU 
agreed that these tools, as all models, have their limitations, but 
nonetheless deemed them appropriate. Additionally, there were several 
comments regarding the choice of the 2011 modeling base year. MANE-VU 
agreed that the choice of base year is critical to the outcome of the 
study. MANE-VU acknowledged that there were newer versions of the 
emission inventories and the need to use the best available inventory 
for each analysis. However, MANE-VU disagreed that the choice of these 
inventories was not appropriate for the analysis. Upwind States also 
suggested that MANE-VU States adopt the 2021 timeline for regional haze 
SIP submissions for the second planning period. MANE-VU agreed with the 
reasons the comments provided, such as collaboration with data and 
planning efforts. However, MANE-VU disagreed that the 2018 timeline 
would prohibit collaboration. Additionally, upwind States noted that 
they would not be able to address the MANE-VU Asks until they finalize 
their SIPs. MANE-VU believed the assumption of the implementation of 
the Asks from upwind States in its 2028 control case modeling was 
reasonable.
---------------------------------------------------------------------------

    \78\ See appendix 9-2 ``Inter-RPO Consultation Briefing Book;'' 
appendix 8-12 ``MANE-VU Regional Haze Consultation Report;'' and 
appendix 8-13 ``National Park Service Letters (April 2018).''
    \79\ See appendix 4-1 ``Federal Land Manager Comments and 
Delaware Response;'' and document ``7. Response to Comment Memo.''
---------------------------------------------------------------------------

    In sum, Delaware participated in the MANE-VU intra- and inter-RPO 
consultation and satisfied the MANE-VU Asks, satisfying 40 CFR 
51.308(f)(2)(ii)(A) and (B). Delaware satisfied 40 CFR 
51.308(f)(2)(ii)(C) by participating in MANE-VU's consultation process, 
which documented the disagreements between the upwind States and MANE-
VU and explained MANE-VU's reasoning on each of the disputed issues. 
Based on the entirety of MANE-VU's intra- and inter-RPO consultation 
and both MANE-VU's and Delaware's responses to States' comments on the 
SIP submission and various technical analyses therein, we propose to 
determine that Delaware has satisfied the consultation requirements of 
40 CFR 51.308(f)(2)(ii).
    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 reductions measures 
that are necessary to make reasonable progress through an RPO, as long 
as the process has been ``approved by all State participants.'' As 
explained above, Delaware chose to rely on MANE-VU's technical 
information, modeling, and analysis to support development of its long-
term strategy. The MANE-VU technical analyses on which Delaware relied 
are listed in the State's SIP submission and include source 
contribution assessments, information on each of the four factors and 
visibility modeling information for certain EGUs, and evaluations of 
emission reduction strategies for specific source categories. Delaware 
also provided supplemental information to further demonstrate the 
technical bases and emission information on which it relied on to 
determine the emission reductions measures that are necessary to make 
reasonable progress. Based on the documentation provided by the State, 
we propose to find Delaware satisfies the requirements of 40 CFR 
51.308(f)(2)(iii).
    Section 51.308(f)(2)(iii) also requires that the emissions 
information considered to determine the measures 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 EPA (or a more recent year), with a 12-month exemption period for 
newly submitted data. Delaware's SIP submission included 2017 NEI 
emission data for NOX, SO2, PM, VOCs and 
NH3, and 2017 Air Markets Program Data (AMPD) emissions for 
NOX and SO2. Delaware's SIP submission also 
included 2019 AMPD for NOX and SO2.\80\ Based on 
Delaware's consideration and analysis of the 2017 and 2019 emission 
data in their SIP submittal and supplemental documentation, EPA 
proposes to find that Delaware has satisfied the emissions information 
requirement in 40 CFR 51.308(f)(2)(iii).
---------------------------------------------------------------------------

    \80\ See section 7.1 of the DE Regional Haze SIP submittal.
---------------------------------------------------------------------------

    We also propose to find that Delaware reasonably considered the 
five additional factors in 40 CFR 51.308(f)(2)(iv) in developing its 
long-term strategy. Pursuant to 40 CFR 51.308(f)(2)(iv)(A), Delaware 
noted that existing and ongoing State and Federal emission control 
programs that contribute to emission reductions through 2028 would 
impact emissions of visibility impairing pollutants from point and 
nonpoint sources in the second implementation period.

[[Page 67036]]

Delaware included in its SIP comprehensive lists of control measures 
with their effective dates, pollutants addressed, and corresponding 
Delaware Administrative Code provisions.\81\
---------------------------------------------------------------------------

    \81\ See section 8.6. of the DE Regional Haze SIP submittal.
---------------------------------------------------------------------------

    Delaware's consideration of measures to mitigate the impacts of 
construction activities as required by 40 CFR 51.308(f)(2)(iv)(B) began 
during the Regional Haze first implementation period. Delaware 
indicated that it has regulations that mitigate potential impacts of 
construction on visibility such as the 7 DE Admin Code 1106, which 
regulates particulate emissions from construction and materials 
handling in the State. In addition, Delaware stated that based on the 
2017 NEI, commercial construction emissions of PM2.5 were 
135 tons, which makes up only 3% of the PM2.5 emissions 
inventory within the State. Delaware concluded that ``Because the 
contribution from construction dust is small, Delaware is determining 
that no changes in its regulatory program for construction dust is 
necessary to make reasonable progress.'' \82\
---------------------------------------------------------------------------

    \82\ 7 DE Admin Code 1106--Particulate Emissions from 
Construction and Materials Handling.
---------------------------------------------------------------------------

    Pursuant to 40 CFR 51.308(f)(2)(iv)(C), source retirements and 
replacement schedules are addressed in section 8.8 of Delaware's 
submission. Source retirements and replacements were considered in 
developing the 2028 emission projections, with on the books/on the way 
retirements and replacements included in the 2028 projections, with on 
the books/on the way retirements and replacements included in the 2028 
projections. The EGU point sources included in the inventories used in 
the MANE-VU contribution assessment and that were subsequently retired 
are identified in Delaware's SIP submittal as McKee Run and Indian 
River Generating Stations. No non-EGU point source retirements in 
Delaware were considered when developing the 2028 emissions 
projections.
    In considering smoke management as required in 40 CFR 
51.308(f)(2)(iv)(D), Delaware explained, in section 8.9 of its 
submission, that emission contribution from prescribed agricultural and 
forest burning within the State are low; PM2.5 statewide 
emissions from prescribed fires were 36 tons and emissions from 
agricultural burning were 60 tons (2% of Delaware's overall 
PM2.5 emissions inventory). Delaware therefore concludes 
that it is unlikely that fires in Delaware for agricultural or forestry 
management cause impacts on visibility in the MANE-VU and nearby Class 
I Areas, including the Brigantine Wilderness Class I Area. Delaware 
states that Smoke Management Plans (SMPs) is a required element of a 
SIP only if it is required to make reasonable progress, and that 
Delaware does not need an official SMP since both a speciation trends 
analysis report \83\ and Delaware's 2014 emissions inventory data show 
that agricultural and forestry management woodsmoke emissions are low. 
However, Delaware notes that under 7 DE Admin 1113 for Open Burning, 
during the months of May to September, both prescribed and agricultural 
burning are prohibited, and even though DNREC does not consider open 
burning regulation an SMP, the regulation does benefit Class I Areas to 
some degree.
---------------------------------------------------------------------------

    \83\ See appendix 8-8 ``Hopke Report''.
---------------------------------------------------------------------------

    Delaware considered the anticipated net effect of projected changes 
in emissions as required by 51.308(f)(2)(iv)(E) by discussing, in 
section 8.10 of its submission, the photochemical modeling for the 
2018-2028 period it conducted in collaboration with MANE-VU. The two 
modeling cases run were a 2028 base case, which considered only on-the-
books controls, and a 2028 control case that considered implementation 
of the MANE-VU Ask. Delaware presented the differences between the base 
and control cases on the 20% most impaired and 20% clearest days for 
each MANE-VU Class I Area.\84\
---------------------------------------------------------------------------

    \84\ See Figure 8-2 of DE Regional Haze SIP submittal at 86.
---------------------------------------------------------------------------

    Because Delaware has reasonably considered each of the five 
additional factors, EPA proposes to find that Delaware has satisfied 
the requirements of 40 CFR 51.308(f)(2)(iv).

F. Reasonable Progress Goals

    Section 51.308(f)(3) contains the requirements pertaining to RPGs 
for each Class I Area. Section 51.308(f)(3)(i) requires a State in 
which a Class I Area is located to establish RPGs--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 paragraph (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 RPGs 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 RPG 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(f)(3)(ii)(A), if the State in which a mandatory Class I Area is 
located establishes an RPG for the most impaired days that provides for 
a slower rate of visibility improvement than the URP, 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 RPG for the most impaired days 
in that Class I Area is above the URP, the upwind State must provide 
the same demonstration. Because Delaware has no Class I Areas within 
its borders, it is subject only to 40 CFR 51.308(f)(3)(ii)(B).
    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. 
Delaware's SIP submittal included MANE-VU's glidepath checks for nearby 
downwind Class I Areas,\85\ such as the Brigantine Wilderness Class I 
Area,\86\ which show that the RPG for the 20 percent most 
anthropogenically impaired days for the affected downwind Class I Areas 
(Acadia, Moosehorn, Great Gulf, Lye Brook, Brigantine, Shenandoah, 
Dolly Sods and James River Face) are not above the URP glidepath, and 
that the RPG for the 20 percent clearest days shows no degradation. In 
addition, the modeled MANE-VU 2028 visibility projections at nearby 
Class I Areas show that the base case 2028 projections for the most 
impaired days at these areas are below the respective 2028 points on 
the URPs. Therefore, we propose it is reasonable to assume that the 
demonstration requirement under 40 CFR

[[Page 67037]]

51.308(f)(3)(ii)(B) as it pertains to these areas will not be 
triggered.
---------------------------------------------------------------------------

    \85\ See appendix 8-6 ``Regional Haze Metrics Trends and HYSPLIT 
Trajectory Analyses''.
    \86\ See Figure 8-2 ``Brigantine Wilderness Area Haze Metrics 
Trends'' in the DE Regional Haze SIP submittal at 86.
---------------------------------------------------------------------------

    EPA proposes to determine that Delaware has satisfied the 
applicable requirements of 40 CFR 51.308(f)(3) relating to RPGs.

G. Monitoring Strategy and Other Implementation Plan Requirements

    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 visibility. A main requirement of this section 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.
    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 mandatory Class I Areas within the State are being achieved. 
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 mandatory Class I Areas both within and 
outside the State. Because Delaware does not have any Class I Areas 
located within its borders, Sec.  51.308(f)(6)(i) and (ii) do not 
apply.
    Section 51.308(f)(6)(iii) requires States with no Class I Areas to 
include 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 in other 
States. States with Class I Areas must establish a monitoring program 
and report data to EPA that is representative of visibility at the 
Class I Areas. The IMPROVE network meets this requirement. Delaware 
stated that, it has conducted receptor modeling and emissions inventory 
analysis to determine source contributions from within the State, and 
the proportional impacts of those sources to areas outside the State. 
Even though, Delaware does not have IMPROVE monitors, Delaware agrees 
that NESCAUM is providing quality technical information by using the 
IMPROVE program data and the Visibility Information Exchange Web System 
(VIEWS) site for the regional haze purposes.
    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. As noted above, 
Delaware does not have any Class I Areas located within its borders, 
therefore this requirement does not apply.
    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. Delaware provides for emissions inventories and 
estimates for future projected emissions by participating in the MANE-
VU RPO and complying with EPA's Air Emissions Reporting Rule (AERR). In 
40 CFR part 51, subpart A, the AERR requires States to submit updated 
emissions inventories for criteria pollutants to EPA's Emissions 
Inventory System (EIS) every three years. The emission inventory data 
is used to develop the NEI, which provides for, among other things, a 
triennial state-wide inventory of pollutants that are reasonably 
anticipated to cause or contribute to visibility impairment.
    Section 7 of Delaware's submission includes tables of NEI data. The 
source categories of the emissions inventories included are: (1) point 
sources, (2) nonpoint sources, (3) non-road mobile sources, and (4) on-
road mobile sources. The point source category is further divided into 
AMPD point sources and non-AMPD point sources.\87\ Delaware included 
NEI emissions inventories for the following years: 2002 (one of the 
regional haze program baseline years), 2008, 2011, 2014, and 2017; \88\ 
and for the following pollutants: NOX, PM10, 
PM2.5, SO2, VOCs, and NH3. Delaware 
also provided a summary of SO2 and NOX emissions 
for AMPD sources for the years of 2016, 2017, 2018, and 2019.\89\
---------------------------------------------------------------------------

    \87\ AMPD sources are facilities that participate in EPA's 
emission trading programs. The majority of AMPD sources are EGUs.
    \88\ See section 7 of the DE Regional Haze SIP submittal at 29.
    \89\ See sections 7.1.1 and 7.1.4 in the Delaware Regional Haze 
SIP submittal.
---------------------------------------------------------------------------

    Section 51.308(f)(6)(v) also requires States to include estimates 
of future projected emissions and include a commitment to update the 
inventory periodically. Delaware relied on the MANE-VU 2028 emissions 
projections for MANE-VU States. MANE-VU completed two 2028 projected 
emissions modeling cases--a 2028 base case that considers only on-the-
books controls and a 2028 control case that considers implementation of 
the MANE-VU Asks.\90\
---------------------------------------------------------------------------

    \90\ See appendix 7-2 ``OTC MANE-VU 2011 Based Modeling Platform 
Support Document October 2018--Final.''
---------------------------------------------------------------------------

    EPA proposes to find that Delaware has met the requirements of 40 
CFR 51.308(f)(6) as described above, including through its continued 
participation in the IMPROVE network and the MANE-VU RPO and its 
ongoing compliance with the AERR, and that no further elements are 
necessary at this time for Delaware 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 RPGs 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. Section 
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

[[Page 67038]]

anthropogenic emissions within or outside the State that 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.
    Delaware's submission describes the status of measures of the long-
term strategy from the first implementation period. As a member of 
MANE-VU, Delaware considered the MANE-VU Asks and adopted corresponding 
measures into its long-term strategy for the first implementation 
period. The MANE-VU Asks were: (1) timely implementation of BART 
requirements; (2) EGU controls including Controls at 167 Key Sources 
that most affect MANE-VU Class I Areas; (3) low sulfur fuel oil 
strategy; and (4) continued evaluation of other control measures. 
Delaware met all the identified reasonable measures requested during 
the first implementation period. During the first planning period for 
regional haze, programs that were put in place focused on reducing 
SO2 emissions. The reductions achieved led to vast 
improvements in visibility at the MANE-VU Class I Areas due to reduced 
sulfates formed from SO2 emissions. Delaware describes in 
section 11 of its submittal control measures put in place during the 
first implementation period to help reduce the emissions of visibility 
impairing pollutants, including NOX and SO2. This 
includes a non-trading emissions control regulation \91\ for EGUs to 
aid in the attainment of ozone and PM ambient air quality standards and 
reduce emissions of neurotoxin mercury. Delaware Stated that the 
regulation ``provides for stringent control of EGU NOX and SO2 
emissions by implementation of unit-specific annual NOX and SO2 mass 
emissions caps and short term (rolling 24-hour) NOX and SO2 emission 
rate limits (lb/MMBTU).'' Delaware added that implementation of the 7 
DE Admin Code 1146, among other measures, like related consent decrees 
and permit conditions, have served to significantly reduce Delaware's 
NOX and SO2 emissions from the EGUs that were 
subject to it and demonstrated it in table 10-8 and Figure 10-1 of the 
DE Regional Haze SIP submittal. The first step change reduction of 
NOX and SO2 emissions happened in 2009, 
corresponding to the promulgation of 7 DE Admin Code 1146. Based on the 
data, by 2019, the EGUs that were subject to this State regulation had 
reduced their SO2 and NOX mass emissions by 
30,197 tpy and 8,005 tpy, which is approximately 99% and 98% emissions 
reductions, respectively.
---------------------------------------------------------------------------

    \91\ See 7 DE Admin Code 1146 ``Electric Generating Unit Multi-
Pollutant Regulation.''
---------------------------------------------------------------------------

    Delaware also described the status of the implementation of primary 
particulate matter BART for the respective eligible EGUs, how they were 
able to meet the 90% or greater SO2 reduction emissions at 
167 stacks inside and outside of MANE-VU, their low sulfur fuel oil 
standards \92\ for the State, and the status of other control methods 
\93\ established during and after the first implementation period.
---------------------------------------------------------------------------

    \92\ See DE Regional Haze SIP submittal section 10.3 at 109.
    \93\ See DE Regional Haze SIP submittal section 8.6 at 76.
---------------------------------------------------------------------------

    EPA proposes to find that Delaware has met the requirements of 40 
CFR 51.308(g)(1) and (2) because its SIP submission describes the 
measures included in the long-term strategy from the first 
implementation period, as well as the status of their implementation 
and the emission reductions achieved through such implementation.
    Section 51.308(g)(3) requires States to assess Reasonable Progress 
Goals, including current visibility conditions and changes, for any 
Class I Areas within the State. As described above, Delaware does not 
have any Class I Areas within its borders, therefore Sec.  51.308(g)(3) 
does not apply.
    Pursuant to 40 CFR 51.308(g)(4), in section 7 of their submittal, 
Delaware provided a summary of emissions of NOX, 
PM10, PM2.5, SO2, VOCs, and 
NH3 from all sources and activities, including from point, 
nonpoint, non-road mobile, and on-road mobile sources, for the time 
period from 2002 to 2017. Delaware also included AMPD data for 
SO2 and NOX emissions for 2016, 2017, 2018 and 
2019 in their submission.
    The reductions achieved by Delaware emission control measures are 
seen in the emissions inventory. Based on Delaware's SIP submission, 
NOX emissions have continuously declined in Delaware from 
2002 through 2017, especially in the point, nonroad and onroad mobile 
sectors. During that period, onroad sources contributed almost half of 
the emissions at 41%, followed by area sources at 21%. Nonroad sources 
contributed 15% and point sources contributed the least at 14%. Table 
7-2 of Delaware's SIP submittal also shows additional NOX 
emissions data from 2016 to 2019 for Delaware's point sources that 
report to EPA's AMPD.\94\ NOX emissions are expected to 
continue to decrease as fleet turnover occurs and the older more 
polluting vehicles and equipment are replaced by newer, cleaner 
ones.\95\
---------------------------------------------------------------------------

    \94\ See DE Regional Haze SIP submittal section 7.1.1.
    \95\ Id
---------------------------------------------------------------------------

    Emissions of PM10 have generally remained relatively 
stable and in a downward trend in Delaware from 2002 to 2017, 
particularly in the point, nonroad and onroad sectors, see section 
7.1.2 and table 7-7 of Delaware's SIP submittal. The variations in the 
onroad are due to changes in emission inventory calculation 
methodologies, which resulted in higher particulate matter estimates in 
the other years than in 2002. The large variation in emissions in the 
nonpoint category is due to changes in calculation methodologies for 
residential wood burning and fugitive dust categories, which have 
varied significantly. Similar trends are observed for emissions of 
PM2.5 in Delaware from 2002 to 2017, see section 7.1.3 and 
table 7-10 of Delaware's SIP submittal. As with PM10, some 
of the variations could be due to changes in estimation methodologies 
for categories such as yard waste burning, paved and unpaved road dust 
and residential wood combustion.
    Emissions of SO2 have shown a steady significant decline 
in Delaware over the period 2002 to 2017, across all multiple 
sectors.\96\ Delaware stated that these reductions are primarily due to 
promulgation of 7 DE Admin Code 1146 and 1108.\97\ Additionally, some 
of these decreases are attributable to the MANE-VU low sulfur fuel 
strategy and the 90% or greater reduction in SO2 emissions 
at 167 EGU stacks, both inside and outside of MANE-VU, requested in the 
``Non-MANE-VU Ask'' for States within MANE-VU for the first regional 
haze planning period.\98\
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    \96\ See section 7.1.4 and table 7-15 of DE Regional Haze SIP 
submittal.
    \97\ Id.
    \98\ Statement of the Mid-Atlantic/Northeast Visibility Union 
(MANE-VU) Concerning a Course of Action within MANE-VU Toward 
Assuring Reasonable Progress. (otcair.org/MANEVU/Upload/Publication/Formal%20Actions/Statement%20on%20Controls%20in%20MV_072007.pdf).
---------------------------------------------------------------------------

    Table 7-21 of Delaware's SIP submittal shows VOC emissions from all 
NEI data categories for the period 2002 to 2017 in Delaware, which have 
shown a steady decline. VOC decreases were achieved in all sectors due 
to Federal and State rules for evaporative sources of VOC emissions 
such as portable fuel containers; architectural, industrial, and 
maintenance coatings (AIM); adhesives and sealants, consumer products; 
and solvent degreasing.\99\ The State added

[[Page 67039]]

that other decreases are due to States' VOC RACT rules and due to State 
motor vehicle Inspection & Maintenance (I&M) programs and the 
permeation of more on-board refueling vapor recovery (ORVR) equipped 
vehicles into the fleet.
---------------------------------------------------------------------------

    \99\ Delaware added that the State has promulgated regulations 
for portable fuel containers, AIM coatings, adhesives and sealants, 
consumer products and solvent degreasing. See section 8.6.3 of DE's 
Regional Haze SIP submittal.
---------------------------------------------------------------------------

    Emissions of NH3 have shown declines in Delaware from 
2002 to 2017; see section 7.1.6 and table 7-24 of Delaware's SIP 
submittal. Ammonia decreases were achieved in the onroad sector due to 
Federal new engine standards for vehicles and equipment. Nonpoint 
increases and decreases from 2002 to 2014 are due to reporting, 
grouping and methodology changes. While ammonia emissions were stable 
between 2014 and 2017 inventories, there was a slight increase in 
ammonia emissions from 2011 and 2014. The increase is due to 
methodology changes and the addition of NH3 emissions from 
domestic and wild animals in 2014.
    EPA is proposing to find that Delaware has satisfied the 
requirements of 40 CFR 51.308(g)(4) by providing emissions information 
for NOX, PM10, PM2.5, SO2, 
VOCs, and NH3 broken down by type of source.
    Delaware uses the emissions trend data in the SIP submission \100\ 
and supporting MANE-VU information \101\ provided to support the 
assessment that anthropogenic haze-causing pollutant emissions in 
Delaware have decreased during the reporting period and that changes in 
emissions have not limited or impeded progress in reducing pollutant 
emissions and improving visibility. Delaware's 2017 emission 
inventories for NOX, PM10, PM2.5, 
SO2, VOCs, and NH3 were lower than their 2014 
emission inventories for those same pollutants emissions.\102\ EPA is 
proposing to find that Delaware has met the requirements of 40 CFR 
51.308(g)(5).
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    \100\ See section 7 of the DE Regional Haze SIP Submittal.
    \101\ See appendices 7-1 and 7-2, ``Technical Support Document 
for 2011 for the Northeastern U.S. Gamma Inventory (January 2018)'' 
and ``Ozone Transport Commission/Mid-Atlantic Northeastern 
Visibility Union 2011 Based Modeling Platform Support Document--
October 2018 Update (October 2018),'' respectively.
    \102\ See section 7 of the DE Regional Haze SIP Submittal.
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I. Requirements for State and Federal Land Manager Coordination

    Section 169A(d) of the Clean Air Act requires States to consult 
with FLMs before holding the public hearing on a proposed regional haze 
SIP, and to include a summary of the FLMs' conclusions and 
recommendations in the notice to the public. In addition, 40 CFR 
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 FLMs' comments.
    The States in the MANE-VU RPO conducted FLM consultation early in 
the planning process concurrent with the state-to-state consultation 
that formed the basis of the RPO's decision making process. As part of 
the consultation, the FLMs were given the opportunity to review and 
comment on the technical documents developed by MANE-VU. The FLMs were 
invited to attend the intra- and inter-RPO consultations calls among 
States and at least one FLM representative was documented to have 
attended seven intra-RPO meetings and all inter-RPO meetings. Delaware 
participated in these consultation meetings and calls.\103\
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    \103\ See appendices 9-1, 9-3 and 9-4 of the DE Regional Haze 
SIP submittal, ``MANE-VU Intra-Regional Ask,'' ``Inter-RPO Ask,'' 
and ``MANE-VU FLM Ask,'' respectively.
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    As part of this early engagement with the FLMs, on April 12, 2018, 
the NPS sent letters to the MANE-VU States requesting that they 
consider specific individual sources in their long-term 
strategies.\104\ NPS used an analysis of emissions divided by distance 
(Q/d) to estimate the impact of MANE-VU facilities. To select the 
facilities, NPS first summed 2014 NEI NOX, PM10, 
SO2, and SO4 emissions and divided by the 
distance to a specified NPS mandatory Class I Federal area. NPS summed 
the Q/d values across all MANE-VU States relative to Acadia, Mammoth 
Cave and Shenandoah National Parks, ranked the Q/d values relative to 
each Class I Area, created a running total, and identified those 
facilities contributing to 80% of the total impact at each NPS Class I 
Area. NPS applied a similar process to facilities in Maine relative to 
Acadia National Park. NPS merged the resulting lists of facilities and 
sorted them by their States. NPS suggested that a State consider those 
facilities comprising 80% of the Q/d total, not to exceed the 25 top 
ranked facilities. The NPS identified two facilities in Delaware in 
this letter.\105\ Delaware included the NPS initial letter in their 
proposed SIP. In a subsequent letter dated October 22, 2018, NPS 
identified two facilities for which more control information was 
desired. Delaware detailed the emission controls and updates to the two 
facilities to address the NPS's request for more information.\106\
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    \104\ Id.
    \105\ See appendix 8-13 ``National Park Service Letters.''
    \106\ See appendix 4-1 ``Federal Land Manager Comments and 
Delaware Response.''
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    On February 11, 2021, Delaware submitted a draft Regional Haze SIP 
to the U.S. Forest Service, the U.S. Fish and Wildlife Service, and the 
National Park Service for a 60-day review and comment period pursuant 
to 40 CFR 51.308(i)(2).\107\ Delaware received comments from the Forest 
Service on March 31, 2021, and from the National Park Service on April 
9, 2021. Delaware responded to the FLM comments and included the 
responses in appendix 4-1 of their submission to EPA, in accordance 
with 40 CFR 51.308(i)(3). Notices of the proposed SIP, availability and 
the public hearing were published on DNREC's website and in the 
Delaware Register, and interested parties were emailed the notice, 
along with air quality contacts from other States, air quality regional 
organizations and the EPA. A public hearing on the proposed SIP 
revision was held on December 29, 2021. Written comments relevant to 
the proposal were accepted until the close of business January 13, 
2022.
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    \107\ Id.
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    For the reasons stated above, EPA proposes to find that Delaware 
has satisfied the requirements under 40 CFR 51.308(i) to consult with 
the FLMs on its regional haze SIP for the second implementation period.
    Delaware's August 2022 SIP submission includes a commitment to 
revise and submit a regional haze SIP by July 31, 2028, and every ten 
years thereafter. The State's commitment includes submitting periodic 
progress reports in accordance with 40 CFR 51.308(f) and a commitment 
to evaluate

[[Page 67040]]

progress towards the reasonable progress goal for each mandatory Class 
I Area located within the State and in each mandatory Class I Area 
located outside the State that may be affected by emissions from within 
the State in accordance with 40 CFR 51.308(g).\108\
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    \108\ See section 12, ``Determination of the Adequacy of the 
Existing Plan'' of the DE Regional Haze SIP submittal.
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V. Proposed Action

    EPA is proposing to approve Delaware's August 8, 2022, SIP 
submission, and supplemental SIP submission dated March 7, 2024, as 
satisfying the regional haze requirements for the second implementation 
period contained in 40 CFR 51.308(f).

VI. Incorporation by Reference

    In accordance with requirements of 1 CFR 51.5, EPA is proposing to 
incorporate by reference specific provisions of the revised title V 
permits for Calpine Christiana Energy Center, Calpine Delaware City 
Energy Center, and Calpine West Energy Center, dated and effective 
December 19, 2023, between DNREC and Calpine Mid-Atlantic Generation, 
LLC, which includes emission limits and associated permit conditions 
for these facilities to comply with Regional Haze requirements for the 
2nd Planning Period, as discussed in section IV of this preamble. These 
permit revisions are contained in DNREC's supplemental SIP submittal 
dated March 7, 2024, submitted on behalf of the State of Delaware; the 
portions of these permit revisions that will be incorporated by 
reference into the SIP are clarified by the DNREC Air Quality Division 
Director via a letter dated May 28, 2024. EPA has made, and will 
continue to make, these materials generally available through 
www.regulations.gov and at the EPA Region 3 Office (please contact the 
person identified in the FOR FURTHER INFORMATION CONTACT section of 
this preamble for more information). Therefore, these materials have 
been proposed for approval by EPA for inclusion in the SIP, will be 
incorporated by reference by EPA into that plan, will be fully 
federally enforceable under sections 110 and 113 of the CAA as of the 
effective date of the final rule of EPA's approval, and will be 
incorporated by reference in the next update to the SIP compilation.

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, EPA's role is to approve State choices, 
provided that they meet the criteria of the CAA. Accordingly, this 
action merely proposes to approve State law as meeting Federal 
requirements and does not impose additional requirements beyond those 
imposed by State law. For that reason, this proposed action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     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 an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     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; and
    Executive Order 12898 (Federal Actions to Address Environmental 
Justice in Minority Populations and Low-Income Populations, 59 FR 7629, 
February 16, 1994) directs Federal agencies to identify and address 
``disproportionately high and adverse human health or environmental 
effects'' of their actions on minority populations and low-income 
populations to the greatest extent practicable and permitted by law. 
EPA defines environmental justice (EJ) as ``the fair treatment and 
meaningful involvement of all people regardless of race, color, 
national origin, or income with respect to the development, 
implementation, and enforcement of environmental laws, regulations, and 
policies.'' EPA further defines the term fair treatment to mean that 
``no group of people should bear a disproportionate burden of 
environmental harms and risks, including those resulting from the 
negative environmental consequences of industrial, governmental, and 
commercial operations or programs and policies.'' The Delaware 
Department of Natural Resources and Environmental Control did not 
evaluate environmental justice considerations as part of its SIP 
submittal; the CAA and applicable implementing regulations neither 
prohibit nor require such an evaluation. EPA did not perform an EJ 
analysis and did not consider EJ in this action. Due to the nature of 
the action being taken here, this action is expected to have a neutral 
to positive impact on the air quality of the affected area. 
Consideration of EJ is not required as part of this action, and there 
is no information in the record inconsistent with the stated goal of 
E.O. 12898 of achieving environmental justice for people of color, low-
income populations, and Indigenous peoples.
    In addition, this proposed rulemaking action, pertaining to 
Delaware's regional haze SIP submission for the second planning period, 
is not approved to apply on any Indian reservation land or in any other 
area where the 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).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Nitrogen dioxide, Ozone, Particulate matter, Sulfur oxides.

Adam Ortiz,
Regional Administrator, Region III.
[FR Doc. 2024-18174 Filed 8-16-24; 8:45 am]
BILLING CODE 6560-50-P