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[Federal Register Volume 89, Number 226 (Friday, November 22, 2024)]
[Rules and Regulations]
[Pages 92573-92600]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-26980]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R04-OAR-2022-0786; FRL-10405-02-R4]

Air Plan Partial Approval and Partial Disapproval; North 
Carolina; Second Period Regional Haze Plan

AGENCY: Environmental Protection Agency (EPA).

[[Page 92574]]

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is approving in part 
and disapproving in part a regional haze State Implementation Plan 
(SIP) revision submitted by the North Carolina Department of 
Environmental Quality, Division of Air Quality (DAQ), dated April 4, 
2022 (``Haze Plan'' or ``2022 Plan'') under the Clean Air Act (CAA or 
Act) and EPA's Regional Haze Rule (RHR) for the regional haze program's 
second planning period. North Carolina's 2022 SIP submission was 
submitted to address the requirement that states must periodically 
revise their long-term strategies for making reasonable progress toward 
the national goal of preventing any future, and remedying any existing, 
anthropogenic impairment of visibility, including regional haze, in 
mandatory Class I Federal areas (hereinafter referred to as ``Class I 
areas''). The SIP submission also addresses other applicable 
requirements for the second planning period of the regional haze 
program. EPA is taking this action pursuant to sections 110 and 169A of 
the Act.

DATES: This rule is effective December 23, 2024.

ADDRESSES: EPA has established a docket for this action under Docket 
Identification No. EPA-R04-OAR-2022-0786. All documents in the docket 
are listed on the regulations.gov website. Although listed in the 
index, some information may not be publicly available, i.e., 
Confidential Business Information or other information whose disclosure 
is restricted by statute. Certain other material, such as copyrighted 
material, is not placed on the internet and will be publicly available 
only in hard copy form. Publicly available docket materials are 
available either electronically through www.regulations.gov or in hard 
copy at the Air Regulatory Management Section, Air Planning and 
Implementation Branch, Air and Radiation Division, U.S. Environmental 
Protection Agency, Region 4, 61 Forsyth Street SW, Atlanta, Georgia 
30303-8960. EPA requests that, if at all possible, you contact the 
person listed in the FOR FURTHER INFORMATION CONTACT section to 
schedule your inspection. The Regional Office's official hours of 
business are Monday through Friday 8:30 a.m. to 4:30 p.m., excluding 
Federal holidays.

FOR FURTHER INFORMATION CONTACT: Michele Notarianni, Multi-Air 
Pollutant Coordination Section, Air Planning and Implementation Branch, 
Air and Radiation Division, U.S. Environmental Protection Agency, 
Region 4, 61 Forsyth Street SW, Atlanta, Georgia 30303-8960. Ms. 
Notarianni can be reached via telephone at (404) 562-9031 or electronic 
mail at [email protected].

SUPPLEMENTARY INFORMATION:

I. Background

    On April 4, 2022, the North Carolina DAQ submitted a revision to 
its SIP to address regional haze for the second planning period. DAQ 
made this SIP submission to satisfy the requirements of the CAA's 
regional haze program pursuant to CAA sections 169A and 169B and 40 
Code of Federal Regulations (CFR) 51.308.\1\ Subsequently, North 
Carolina submitted a letter, dated July 30, 2024 (Commitment Letter), 
requesting partial conditional approval of its Haze Plan and committing 
to submit a SIP revision containing specific enforceable measures no 
later than one year from the effective date of a final conditional 
approval action.\2\ Through a notice of proposed rulemaking published 
on August 20, 2024, (89 FR 67341) (hereinafter referred to as the 
NPRM), EPA proposed to approve in part and conditionally approve in 
part North Carolina's April 4, 2022, SIP submission addressing the 
regional haze requirements for the second planning period contained in 
the CAA and 40 CFR 51.308. Comments on the NPRM were due on or before 
September 19, 2024. EPA received four sets of relevant comments on the 
NPRM.
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    \1\ In a letter dated August 15, 2022, EPA found that North 
Carolina's Haze Plan meets the completeness criteria outlined in 40 
CFR part 51, appendix V. A completeness determination does not 
constitute a finding on the merits of the submission or whether it 
meets the relevant criteria for SIP approval. The August 15, 2022, 
letter is included in the docket for this rulemaking.
    \2\ The Commitment Letter is in the docket for this rulemaking.
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    After reviewing the entirety of the record including comments 
submitted, EPA is now taking final action to approve in part and 
disapprove in part North Carolina's Haze Plan. Specifically, EPA is 
approving the portions of the Haze Plan addressing the requirements of 
40 CFR 51.308(f)(1), (f)(4) through (6), and (g)(1) through (5). EPA is 
disapproving the portions of the Haze Plan addressing the requirements 
of 40 CFR 51.308(f)(2) and (3) and (i)(2) through (4) due to the 
inadequate record associated with the four-factor analysis (FFA) for 
Domtar Paper, LLC (Domtar) located in Plymouth, North Carolina, as 
described in more detail in section II. EPA is not finalizing its 
previously proposed conditional approval.\3\ Therefore, the issues 
identified as part of the proposed conditional approval and in the 
Commitment Letter are now subsumed under the broader partial 
disapproval.
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    \3\ Under CAA section 110(k)(4), EPA may conditionally approve a 
SIP revision based on a commitment from a state to adopt specific 
enforceable measures by a date certain, but not later than one year 
from the date of conditional approval of the plan revision. In its 
Commitment Letter, the State committed to submit a SIP revision 
containing specific enforceable measures no later than one year from 
the effective date of a final conditional approval action. Because 
EPA is not finalizing the proposed conditional approval, North 
Carolina is not required to submit that SIP revision.
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    Disapproving a SIP submission establishes a two-year deadline for 
EPA to promulgate a Federal Implementation Plan (FIP) to address the 
relevant requirements under CAA section 110(c), unless EPA approves a 
subsequent SIP submission that meets these requirements.\4\ Therefore, 
EPA will be obligated under CAA section 110(c)(1) to promulgate a FIP 
within two years after the effective date of this partial disapproval, 
unless the State submits, and EPA approves, a SIP revision that 
satisfies the requirements of 40 CFR 51.308(f)(2) and (3) and (i)(2) 
through (4).
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    \4\ North Carolina's Haze Plan was not submitted to address a 
requirement of part D, title I of the CAA, and is not required in 
response to a finding of substantial inadequacy as described in CAA 
section 110(k)(5) (SIP Call), so the partial disapproval will not 
trigger any offset or highway sanctions clocks. See CAA section 
179(a).
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    This final action represents a logical outgrowth of the proposal, 
following EPA's proposed partial approval and partial conditional 
approval, and receipt of public comments. EPA specifically solicited 
comments on the adequacy of DAQ's analyses, including the FFAs, 
determination of controls necessary for reasonable progress, and the 
adequacy of the submitted permit conditions, including associated 
monitoring, recordkeeping, and reporting, and whether the State met the 
requirements of 40 CFR 51.308(f)(2)(i) through (iv). See 89 FR 67358. 
Through this solicitation of comment, the public was on notice that EPA 
was specifically interested in the public's perspective on its 
conclusions and may ultimately change its conclusions. A logical 
outgrowth of a proposal is to refrain from taking the proposed step. 
See Am. Iron & Steel Inst. v. EPA, 886 F.2d 390, 400 (D.C. Cir. 1989). 
For action on SIP submittals, EPA is required to act, so the Agency may 
not refrain from acting. As such, it is reasonable to view a 
disapproval as a logical outgrowth of a proposed approval (or proposed 
conditional approval) if comments

[[Page 92575]]

cause EPA to change its proposed conclusions. Consistent with CAA 
section 110(k)(3), EPA may approve in part portions of the SIP 
submittal if those portions meet all applicable requirements.

II. Response to Comments

    In response to the NPRM, EPA received comment letters from the 
National Parks Conservation Association (NPCA), Sierra Club, the 
Coalition to Protect America's National Parks, Center for Biological 
Diversity, and Southern Environmental Law Center (collectively referred 
to as the ``Conservation Groups''); U.S. National Park Service (NPS); 
and 7 Directions of Service, Blue Ridge Outdoors Magazine, Center for 
Biological Diversity, CleanAIRE NC, Coalition to Protect America's 
National Parks, Dogwood Alliance, Forest Keeper, Friends of Big Ivy, I 
Heart Pisgah, Mountain True, NPCA, North Carolina Black Alliance, and 
Toxic Free North Carolina (collectively referred to as the 
``Organizations''). Additionally, EPA received comments from two 
members of the public. One set of comments from a member of the public 
is not relevant to this action, and the other set of comments is 
addressed below. All comments received are available in the docket for 
this action. A summary of the significant comments received from these 
commenters and EPA's responses to these comments is below.
    Comment 1: The Conservation Groups contend that EPA's proposal to 
approve North Carolina's reliance on the Visibility Improvement State 
and Tribal Association of the Southeast's (VISTAS') visibility modeling 
is arbitrary and capricious because the Agency ignored significant 
flaws in this modeling. They state that they informed VISTAS and EPA of 
significant errors in the visibility modeling through a 2021 letter,\5\ 
EPA did not acknowledge these errors in the NPRM, and these errors 
affected the source selection process for all of the VISTAS states. 
Consequently, they assert that North Carolina improperly excluded major 
sources of haze-forming pollution from FFAs.\6\ These alleged errors 
are addressed in comments 1.a through 1.c below.
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    \5\ Exhibit 11 of the Conservation Groups' comments contains the 
May 12, 2021, letter regarding the VISTAS regional haze modeling for 
the second planning period.
    \6\ 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.''
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    Comment 1.a: The Conservation Groups contend that the VISTAS 
modeling significantly underpredicted the contribution of sulfates to 
visibility impairment at Class I areas on the 20 percent most impaired 
days and that this underprediction was largest during the summer months 
when visibility impairment is most problematic.\7\ They also assert 
that these errors resulted in the modeling not meeting VISTAS' model 
performance goals and modeling acceptance criteria for a number of 
Class I areas. They further assert that although North Carolina claims 
that it corrected for this underprediction through the use of relative 
response factors (RRFs), neither North Carolina nor EPA assessed 
whether use of RRFs adequately corrected for errors in the modeling.
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    \7\ Areas statutorily designated as mandatory Federal Class I 
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 
section 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.
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    Response 1.a: EPA disagrees that there are significant flaws in 
North Carolina's 2028 visibility modeling that resulted in excluding 
major sources of haze-forming pollution from evaluation via FFAs for 
the second planning period. As the Conservation Groups state, North 
Carolina relied upon the photochemical visibility modeling performed by 
VISTAS to project the impact of the State's 2028 sulfur dioxide 
(SO2) and nitrogen oxides (NOX) emissions on 
visibility in both in-state and out-of-state Class I areas. VISTAS 
performed the modeling in accordance with the principles described 
within EPA's ``Modeling Guidance for Demonstrating Air Quality Goals 
for Ozone, PM2.5 and Regional Haze'' (2018 Modeling 
Guidance).\8\ In 2018, EPA approved \9\ the Quality Assurance Project 
Plan prepared by VISTAS for performing the modeling and also reviewed 
and provided comments on the VISTAS Modeling Protocol. EPA also 
reviewed the VISTAS final modeling reports and data relied upon by 
North Carolina, and they appear reasonable.
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    \8\ ``Modeling Guidance for Demonstrating Air Quality Goals for 
Ozone, PM2.5 and Regional Haze,'' EPA 454/R-18-009, 
November 29, 2018, available at: https://www.epa.gov/sites/default/files/2020-10/documents/o3-pm-rh-modeling_guidance-2018.pdf.
    \9\ The April 3, 2018, Quality Assurance Project Plan for the 
VISTAS II Regional Haze Project is located in appendix A-1 of the 
Haze Plan.
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    Regarding sulfate predictions, figure 6-7 in North Carolina's Haze 
Plan shows the results of the normalized mean bias and normalized mean 
error statistical model performance tests for sulfates across the 
VISTAS region. Figure 6-7 does show that the modeled sulfate levels are 
biased low, with some values falling outside of the model performance 
criteria. However, as discussed below, these biases are not uncommon in 
photochemical modeling analyses and can be addressed with additional 
analyses. Table 6-10 in the Haze Plan summarizes the sulfate model 
performance criteria for multiple statistical tests, and figures 6-32 
through 6-55 in the Haze Plan graphically depict model performance at 
the Great Smoky Mountains National Park (Great Smoky Mountains) (North 
Carolina/Tennessee); Linville Gorge National Wilderness Area (Linville 
Gorge); and Swanquarter National Wilderness Area (Swanquarter) which 
are three of the five Class I areas in North Carolina.\10\
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    \10\ North Carolina has five Class I areas, two of which are 
shared with Tennessee: Great Smoky Mountains (North Carolina/
Tennessee); Linville Gorge; Swanquarter; Shining Rock National 
Wilderness Area (Shining Rock); and Joyce Kilmer-Slickrock National 
Wilderness Area (Joyce Kilmer) (North Carolina/Tennessee). Joyce 
Kilmer relies on data from the Great Smoky Mountains IMPROVE 
monitoring site (GRSM1) because it does not have an IMPROVE monitor 
and the Shining Rock IMPROVE monitor did not have valid data in 2011 
so model performance could not be evaluated.
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    Model bias and error, either high or low, is not uncommon in 
photochemical modeling analyses due to uncertainties in model inputs 
and the scientific model formulation, and the fact that all air quality 
models are simplified approximations of the complex phenomena of 
atmospheric chemistry, fate, and transport of pollutants. Section 6.0 
of EPA's 2018 Modeling Guidance discusses uncertainties that may affect 
model results and states that following the recommendations in the 
Guidance should help mitigate the uncertainty as much as possible. 
North Carolina acknowledges in the Haze Plan that model performance is 
biased low on the 20 percent most impaired days and provided an 
explanation of why this modeling was nonetheless appropriate for its 
regulatory determinations in the Haze Plan (which references the 2018 
Modeling Guidance in several instances). The 2018 Modeling Guidance 
states that it is not appropriate to use a ``bright-line test'' for 
distinguishing between adequate and inadequate photochemical model 
performance for a single performance test statistic.\11\ EPA's 2018 
Modeling Guidance instead recommends using a ``weight of evidence'' 
approach for

[[Page 92576]]

evaluating model performance holistically.\12\
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    \11\ See 2018 Modeling Guidance at p. 69 (``Further, even with a 
single performance test, it is not appropriate to assign ``bright 
line'' criteria that distinguish between adequate and inadequate 
model performance.'').
    \12\ See id. (``[T]he EPA recommends that a ``weight of 
evidence'' approach be used to determine whether a particular 
modeling application is valid for assessing the future attainment 
status of an area.'').
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    As discussed in section 5.2(d) of EPA's ``Guideline on Air Quality 
Models'' contained in 40 CFR part 51, appendix W, there are no specific 
levels of any model performance metric that indicate acceptable model 
performance. The decision regarding acceptability is heavily influenced 
by professional judgment of the reviewing authority, which is EPA in 
this case. Based upon the overall performance of the model for all 
pollutants affecting visibility, considered holistically, North 
Carolina's conclusions that the modeling is acceptable for use in the 
regional haze SIP analyses appear reasonable, and North Carolina 
provided a reasonable explanation of the model bias.
    Just as importantly, North Carolina's steps to correct for this 
model bias appear reasonable. The Haze Plan explains that the model is 
applied in a relative sense through the calculation of RRFs following 
the procedures in 2018 Modeling Guidance for calculating 2028 future 
year visibility impacts, which mitigates concerns about the low bias in 
the sulfate model predictions. As described in EPA's 2018 Modeling 
Guidance, RRFs are ``the fractional change in air quality 
concentrations that is simulated due to emissions changes between a 
base and a future year emissions scenario.'' \13\
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    \13\ See id. at p. 103.
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    Applying the model in a relative sense using the RRFs is an 
important tool in mitigating the impacts of the sulfate modeling 
underpredictions in the 2011 baseline year on the model projections for 
the 2028 future year. Section 4.1 of the 2018 Modeling Guidance 
provides a detailed explanation of why EPA recommends photochemical 
modeling be applied in a relative sense and explains that problems 
posed by model bias are expected to be reduced when using the relative 
approach. Section 7.2.6.1 of North Carolina's Haze Plan explains the 
calculation of 2028 visibility estimates using the RRF approaches 
contained in EPA's 2018 Modeling Guidance. Using the RRF approach with 
an average of five years of Interagency Monitoring of Protected Visual 
Environments (IMPROVE) \14\ data on the 20 percent most impaired days 
and 20 percent clearest days along with the relative percent modeled 
change in all of the particulate matter (PM) species between 2011 and 
2028 reduces the influence of the low bias in sulfate-modeled (and 
other PM species) values in the 2011 baseline year. The 2028 visibility 
impairment projection is derived primarily from the five-year average 
of actual IMPROVE monitoring data in 2009-2013 that was then scaled in 
a relative sense by the modeling results. If the model was being 
applied in an absolute sense, the low bias in the sulfate modeled 
values would have a larger impact on the 2028 visibility projections. 
For these reasons, North Carolina's use of the VISTAS model results to 
inform source selection appears reasonable due to the use of RRFs to 
minimize the impacts of model bias.
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    \14\ IMPROVE visibility monitoring data is available at: https://vista.cira.colostate.edu/Improve/.
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    Comment 1.b: The Conservation Groups state that VISTAS relied on an 
``outdated'' 2011 baseline year for its 2028 future year emissions 
projections and assumed that electric generating units (EGUs) would 
operate in the exact same manner in 2028 as they did in 2011. Thus, 
they assert that the model assumptions and results are incorrect 
because EGUs are likely to have different load utilization in 2028 than 
in 2011.
    Response 1.b: North Carolina's use of a 2011 base emissions 
inventory year to project emissions out to 2028 (the end of the second 
planning period) appears reasonable in this instance. Although it is 
always preferable to use the most recent information available for 
modeling, the 2011 baseline year inventory used by VISTAS was the 
latest region-wide inventory available at the time that North 
Carolina's SIP submittal was being developed during the VISTAS 
technical work, which took place from December 2017 to February 26, 
2021.\15\ In EPA's experience, coordination among states such as those 
in the VISTAS region takes time, and the modeling involved is time-
consuming, highly technical, and resource intensive. The modeling 
generally requires hundreds of hours of time to gather the model input 
data (e.g., emissions, meteorology, land-use, etc.), prepare modeling 
protocols, perform the modeling, and analyze the results. The 
computational resources to run photochemical models are also very 
large. ``Mainframe'' clusters of a large number of computer processors 
are required to run the models, and even using these powerful 
computers, it takes weeks of computer run-time for a full-year model 
simulation. Additionally, EPA's newer 2016-based modeling platform only 
became available in September 2019, after VISTAS had already invested a 
considerable amount of time and money into the regional haze modeling 
analysis.\16\ EPA develops the National Emissions Inventory (NEI) 
suitable for use in such models every three years.\17\ By design, the 
regional haze program requires states to spend significant time in the 
planning phase, and this generally necessitates the use of a baseline 
year that is substantially earlier than the date the state submits its 
SIP to EPA.
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    \15\ See ``Timeline'' for the VISTAS II Regional Haze Project 
at: https://www.metro4-sesarm.org/content/vistas-regional-haze-project-intro.
    \16\ See ``Technical Support Document for EPA's Updated 2028 
Regional Haze Modeling'' at: https://www.epa.gov/visibility/technical-support-document-epas-updated-2028-regional-haze-modeling.
    \17\ For more information on the NEI, see: https://www.epa.gov/air-emissions-inventories/national-emissions-inventory-nei.
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    In addition, there is no RHR requirement regarding the baseline 
year for regional photochemical modeling (nor is photochemical modeling 
required). At the time VISTAS began their regional haze modeling, EPA 
did not have a more recent baseline emissions inventory year available 
for state use in the second period regional haze plans. Furthermore, 
North Carolina explains the use of this particular baseline year and 
states that the 2011 emissions inventory was the most recently 
available quality assured statewide emissions inventory when the VISTAS 
project began.\18\ Moreover, prior to using this data, the State 
discussed the selection of this baseline year emissions inventory and 
received confirmation from EPA to use this emissions inventory.\19\
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    \18\ See Haze Plan at p. 24 (``The year 2011 was selected as the 
modeling base year because the VISTAS 2028 emissions inventory is 
based on the 2011 Version 6 EPA modeling platform, which at the 
commencement of the VISTAS second round of planning for regional 
haze was the most current, complete modeling platform available. For 
the analyses in this SIP, this period consists of those years 
surrounding 2011 (i.e., 2009-2013).''). See also Haze Plan, p. 49 
(``Calendar year 2011 satisfies the criteria in EPA's modeling 
guidance episode selection discussion and is consistent with the 
base year modeling platform. In addition, the 2011/2028 modeling 
platform was the most recent available platform when VISTAS started 
its modeling work. EPA's 2016-based platform became available at a 
later date after VISTAS had already invested a considerable amount 
of time and money into the modeling analysis. Using the 2016-based 
platform was not feasible from a monetary perspective, nor could 
such work be done in a timely manner.'').
    \19\ See the January 29, 2018, email from EPA (Richard Wayland) 
regarding use of a 2011 base year by VISTAS for regional haze in the 
docket for this rulemaking.
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    The 2011 emissions inventory was used to estimate emissions of 
visibility impairing pollutants in 2028. VISTAS applied reductions 
expected from

[[Page 92577]]

Federal and state regulations on the visibility impairing pollutants 
NOX, PM, and SO2. North Carolina's 2028 emissions 
projections are based on the State's technical analysis of the 
anticipated emissions rates and level of activity for EGUs, other point 
sources, non-point sources, on-road sources, and off-road sources based 
on their emissions in the 2011 base year, considering growth and 
additional emissions controls to be in place by 2028. In addition, the 
VISTAS emissions inventory for 2028 accounts for post-2011 emission 
reductions from promulgated Federal, state, local, and site-specific 
control programs. North Carolina's modeling of the EGUs and non-EGUs 
for the growth factors appears reasonable. The 2011 baseline year to 
2028 future year emissions projections were modeled to account for 
projected changes in emissions over the second planning period.
    Although North Carolina used the 2011 year as its emissions 
inventory base year, North Carolina also examined more recent emission 
inventory information for SO2 and NOX for the 
years 2017, 2018, and 2019 and compared these emissions to the 2028 
emission projections that were used for modeling purposes in section 
7.7.3 and tables 7-41 and 7-42 of its Haze Plan. This appears compliant 
with 40 CFR 51.308(f)(2)(iii) and is another backstop that helps to 
ensure that the State adequately considered more recent emissions 
inventory information. The technical information provided in the docket 
documents the projected 2028 emissions inventory in the Haze Plan. 
Given the aforementioned reasons, the use of the 2011 baseline year by 
VISTAS (and thus North Carolina) appears reasonable.
    Comment 1.c: The Conservation Groups state that VISTAS used 
``outdated'' monitoring data for its 2028 future year projections that 
did not reflect an observed shift in nitrate contribution to visibility 
impairment in the southeastern United States in the recent past. They 
therefore contend that this resulted in the exclusion of major 
NOX sources from the modeling results.
    Response 1.c: Regarding the Conservation Groups' claims that the 
2009-2013 modeling base period did not reflect more recent changes in 
nitrate contributions, EPA discussed its views on this issue in detail 
in the NPRM. Nitrates are also discussed in response 3, below. EPA 
agrees that during the 2009-2013 timeframe, nitrate impacts have become 
more significant on some of the 20 percent most impaired days, 
especially taking into account the significant decrease in 
SO2 emissions and acknowledged this in the NPRM. However, 
North Carolina's focus on SO2 emitting sources during this 
period appears reasonable because sulfates remain the dominant 
visibility impairing pollutant at the Class I areas affected by North 
Carolina.
    For the reasons discussed in responses 1.a through 1.c, the VISTAS 
modeling appears adequate for North Carolina's use in selecting sources 
for a FFA for the second planning period. However, the requirement to 
consider the four factors in establishing the long-term strategy (LTS) 
at 40 CFR 51.308(f)(2) and CAA section 169A(g)(1) encompasses the 
selection of sources for further analysis, and as discussed above, EPA 
is disapproving the portions of the Haze Plan addressing 40 CFR 
51.308(f)(2) due to the inadequate record associated with the Domtar 
FFA.
    Comment 2: The Conservation Groups claim the errors in the VISTAS 
modeling discussed in comment 1 above were carried forward into the 
source selection process for VISTAS states, including North Carolina, 
and that those errors caused VISTAS, and the states that relied on the 
VISTAS process, to improperly exclude sources from FFAs. In addition to 
the impact of the modeling errors, they state that North Carolina used 
VISTAS' unreasonable source screening process using Area of Influence 
(AoI) and Particulate Matter Source Apportionment Technology (PSAT) 
analyses and unreasonably high source selection thresholds. They 
therefore contend that EPA's proposal to approve the State's source 
selection method is arbitrary and capricious. The Conservation Groups' 
specific comments on this topic are addressed in comments 2.a through 
2.g, below.
    Comment 2.a: The Conservation Groups claim that the State employed 
unreasonably high source selection thresholds for AoI, which were too 
restrictive and resulted in the identification of only five North 
Carolina sources at that step. They assert that by using a percentage 
source selection threshold, the calculated threshold in absolute 
visibility impact terms was higher for Class I areas with the most 
severe visibility impairment. The Conservation Groups contend that 
fewer sources were identified at the AoI step for Class I areas with 
the worst visibility impairment. They also state that for the areas 
with the worst visibility impairment, more sources should be selected 
to make progress toward the natural visibility goal. In addition, they 
assert that neither North Carolina nor EPA provide justification for a 
three percent threshold at the AoI step, making its use arbitrary.
    Response 2.a: EPA disagrees with this comment. As explained in the 
NPRM, the RHR does not require states to consider controls for all 
sources, all source categories, or any or all sources in a particular 
source category. See 89 FR 67346. Nor does the RHR expressly specify 
criteria for minimum source selection thresholds.
    These flexibilities, however, are not unbounded. The RHR requires 
that ``[t]he State should consider evaluating major and minor 
stationary sources or groups of sources, mobile sources, and area 
sources. The State must include in its implementation plan a 
description of the criteria it used to determine which sources or 
groups of sources it evaluated and how the four factors were taken into 
consideration in selecting the measures for inclusion in its long-term 
strategy.'' \20\ In addition, the technical basis for source selection 
must also be documented, as required by 40 CFR 51.308(f)(2)(iii), and 
North Carolina discussed the criteria it used to determine which 
sources or groups of sources were evaluated by the State, including the 
use of AoI analysis, photochemical modeling (e.g., PSAT), and 
associated source selection thresholds for AoI and PSAT tagging in its 
Haze Plan. North Carolina documented its use of these approaches in 
extensive detail within section 7.5 of the Haze Plan and appendices D-1 
and D-2 of the Haze Plan (relating to AoI analysis) and section 7.6 of 
the Haze Plan and appendices E-1a, E-1b, E-2a, E-2b, E-2c, E-2d, E-2e, 
E-2f, E-3, E-4, E-5, E-6, E-7a, E-7b, and E-8 of the Haze Plan 
(relating to PSAT modeling).
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    \20\ See 40 CFR 51.308(f)(2)(i).
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    North Carolina's source selection methodology--including the use of 
an AoI threshold of greater than or equal to three percent for sulfate 
and nitrate combined at any North Carolina Class I area for all sources 
within and outside of the State for follow-up PSAT tagging, and a one 
percent PSAT threshold on a pollutant-by-pollutant basis for source 
selection--appears reasonable and is documented in the Haze Plan. A 
specific approach is not required by the RHR.\21\
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    \21\ Both of these approaches (AoI and PSAT) are example methods 
in EPA's August 20, 2019, guidance titled: ``Guidance on Regional 
Haze State Implementation Plans for the Second Implementation 
Period'' (``2019 Guidance'') which is available at: https://www.epa.gov/sites/default/files/2019-08/documents/8-20-2019_-_regional_haze_guidance_final_guidance.pdf. See subsection ``b) 
Estimating baseline visibility impacts for source selection'' on 
pages 12-15 of the 2019 Guidance. Photochemical modeling (zero-out 
and/or source apportionment is listed as item 4 on page 13 of the 
2019 Guidance. VISTAS' AoI analyses involve items 1-3 on p. 13 of 
the 2019 Guidance.

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[[Page 92578]]

    The results of this methodology also appear reasonable. North 
Carolina selected for further analysis the three sources with the 
largest visibility impacts (accounting for both SO2/sulfate 
and NOX/nitrate \22\) at North Carolina and nearby Class I 
areas. On the whole, SO2 emissions from the three in-state 
sources selected by North Carolina for FFAs--Blue Ridge Paper 
Products--Canton Mill (BRPP); Domtar; \23\ and PCS Phosphate Inc.--
Aurora (PCS)--are projected to impact visibility at Class I areas above 
North Carolina's one percent PSAT threshold.
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    \22\ North Carolina selected sources for PSAT modeling based on 
the combined impact of sulfate plus nitrate. Sulfates and nitrates 
were modeled together in the PSAT modeling with the other PM species 
that impact visibility (e.g., direct PM, organic carbon, elemental 
carbon, etc.). There were no sources with a sulfate impact below the 
PSAT threshold(s), but a sulfate plus nitrate impact above the 
threshold(s).
    \23\ On December 1, 2023, DAQ issued Air Quality Permit No. 
04291T51 authorizing modifications to the Domtar facility, which is 
available at: https://edocs.deq.nc.gov/AirQuality/DocView.aspx?id=457541&dbid=0&repo=AirQuality&searchid=c271acf8-6535-4306-8cfb-9a0caa2b3d97. Because these authorized permit 
modifications are subsequent to the North Carolina SIP submission, 
North Carolina did not consider the modification to determine 
reasonable progress in the second planning period.
---------------------------------------------------------------------------

    Most anthropogenic impacts to visibility at the North Carolina 
Class I areas come from outside of North Carolina and, in fact, they 
primarily come from outside of the VISTAS states. This is also 
illustrated in table 7-14 of the Haze Plan, which provides the 
contributions from 2028 SO2 and NOX emissions to 
visibility impairment from all source sectors for the 20 percent most 
impaired days in units of inverse megameters (Mm-1). The 
entries in table 1, below, taken from table 7-14 of the Haze Plan, show 
the contributions made from North Carolina, all other VISTAS states, 
and other Regional Planning Organizations (RPOs) to North Carolina's 
Class I areas.

 Table 1--Contributions of 2028 SO2 and NOX Emissions From All Source Sectors to Visibility Impairment for the 20 Percent Most Impaired Days for Class I
                                                                 Areas in North Carolina
                                                                        [Mm-1] *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                            Sulfate + nitrate visibility impairment (Mm-1)
                                            ------------------------------------------------------------------------------------------------------------
                                                                                                                                              Boundary +
                                                                                                                                              all other
                Class I area                   2028 total    2028 sulfate +               All other                                            regions
                                               impairment        nitrate         NC         VISTAS       CENRAP       LADCO       MANE-VU       within
                                              (all species)    impairment                   states     region **    region **    region **      VISTAS
                                                                                                                                               modeling
                                                                                                                                                domain
--------------------------------------------------------------------------------------------------------------------------------------------------------
Great Smoky Mountains......................           45.75           24.17        0.89         9.77         1.87         3.74         1.57         6.33
Joyce Kilmer...............................           45.12           22.48        0.43         5.62         2.96         6.84         0.82         5.81
Linville Gorge.............................           42.52           19.47        0.95         4.19         2.55         5.54         1.15         5.09
Shining Rock...............................           42.09           19.20        1.13         3.97         2.80         5.11         0.75         5.44
Swanquarter................................           46.39           21.14        1.83         3.87         0.72         4.19         3.23         7.30
--------------------------------------------------------------------------------------------------------------------------------------------------------
* As noted in North Carolina's Haze Plan, the columns to the right of ``Projected 2028 Impairment on 20% Most Impaired Days'' do not add up to the
  values in the ``Projected 2028 Impairment on 20% Most Impaired Days'' column due to international emissions and boundary emissions.
** ``CENRAP'' refers to Central Regional Air Planning Association (which is associated with the Central States Air Resource Agencies (CENSARA));
  ``LADCO'' refers to Lake Michigan Air Directors Consortium; ``MANE-VU'' refers to Mid-Atlantic/Northeast Visibility Union; ``WRAP'' refers to Western
  Regional Air Partnership. See also: https://www.epa.gov/visibility/visibility-regional-planning-organizations.

    Table 1 illustrates that North Carolina's in-state emissions 
account for a relatively small fraction of total sulfate plus nitrate 
visibility impairment at North Carolina's Class I areas which is as 
follows: approximately 3.68 percent for Great Smoky Mountains; 1.91 
percent for Joyce Kilmer; 4.88 percent for Linville Gorge; 5.89 percent 
for Shining Rock; and 8.66 percent for Swanquarter.\24\
---------------------------------------------------------------------------

    \24\ These percentages were calculated by dividing the ``NC'' 
column by the ``2028 Sulfate + Nitrate Impairment'' column and 
multiplying by 100.
---------------------------------------------------------------------------

    The RHR affords North Carolina flexibility in its choice of both 
AoI and PSAT thresholds. North Carolina's source selection methodology 
appears reasonable, and therefore, North Carolina's choice of the three 
largest impacting sources in the State using its AoI and PSAT criteria 
appears adequate.
    Comment 2.b: The Conservation Groups state that VISTAS considered 
sulfate and nitrate separately in the PSAT model analyses, which the 
Conservation Groups allege does not align with how these pollutants 
actually function in the atmosphere, where sulfate and nitrate act in 
combination, along with other precursors, to contribute to visibility 
impairment. As a result, they argue that VISTAS likely underestimated 
the overall visibility impact of individual sources in its PSAT 
analysis.
    Response 2.b: EPA disagrees with this comment. In the AoI screening 
analysis, VISTAS used the combined sulfate plus nitrate values to 
select sources to tag for the refined PSAT source apportionment 
modeling analyses. Section 7.5.5 of the Haze Plan explains how North 
Carolina used the results of the AoI analysis to select sources for 
further evaluation with PSAT. This section shows that facilities 
contributing greater than or equal to three percent for sulfate and 
nitrate combined at any North Carolina Class I area for all sources 
within and outside of the State were selected for PSAT tagging. See 
tables 7-20 through 7-24 for the specific sources with sulfate plus 
nitrate values greater than North Carolina's AoI source selection 
threshold.
    Also, contrary to the Conservation Groups' assertion, sulfates and 
nitrates were modeled together in the PSAT modeling with the other PM 
species that impact visibility (e.g., direct PM, organic carbon, 
elemental carbon, etc.). Section 7.6.2 of the Haze Plan summarizes the 
results of the PSAT modeling. This section states that: ``The adjusted 
PSAT results were used to calculate the percent contribution of each 
tagged facility to the total sulfate and nitrate point source (EGU + 
non-EGU) contribution at each Class I area.'' \25\ Tables 7-31 through 
7-35 contain the specific PSAT results for each of North Carolina's 
Class I areas. It is true that North Carolina considered the PSAT 
modeled results for sulfate and nitrate separately to compare against 
its selected one percent threshold. However, no additional sources 
would have been identified by using a combined sulfate plus nitrate 
metric. For these reasons, North Carolina's approach appears 
reasonable.
---------------------------------------------------------------------------

    \25\ See Haze Plan at p. 227.

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[[Page 92579]]

    Comment 2.c: The Conservation Groups state that VISTAS used an 
outdated 2028 emissions projection to ``tag'' sources. They note that 
although VISTAS documented that the initial 2028 emission inventory 
projections were updated for the final modeling, the associated PSAT 
modeling did not use the final 2028 inventory. They state that VISTAS 
scaled predicted sulfate and nitrate to the corresponding changes in 
SO2 and NOX emissions using a linear relationship 
between SO2 and NOX emissions and sulfate and 
nitrate concentrations. They argue ample evidence shows that there is a 
non-linear relationship between emissions and sulfate/nitrate 
concentrations. Moreover, the Conservation Groups contend that North 
Carolina significantly underestimated future 2028 emissions for 
multiple sources, pointing to a comparison of North Carolina's 2028 
future emission projections against recent actual emissions for five 
Duke Energy EGUs as an example: Duke Energy Carolinas (DEC)--Belews 
Creek Steam Station (DEC--Belews Creek), DEC--Cliffside Steam Station 
(DEC--Cliffside), DEC--Marshall Steam Station (DEC--Marshall), Duke 
Energy Progress, LLC (DEP)--Mayo Electric Generating Plant (DEP--Mayo), 
and DEP--Roxboro Steam Electric Plant (DEP--Roxboro).\26\
---------------------------------------------------------------------------

    \26\ See table 2 of the 2024 Kordzi Report in Exhibit 1 of the 
Conservation Groups' comment letter.
---------------------------------------------------------------------------

    They argue that this comparison shows that the State severely 
underestimated future emissions for these facilities and note that 
nothing in the Haze Plan indicates that there have been federally 
enforceable changes to these Duke Energy EGUs' operating parameters 
that would justify such large differences between recent actual 
emissions and future year 2028 projections.
    Response 2.c: Regarding the Conservation Groups' claim that VISTAS 
used an outdated 2028 emissions projection to select sources for the 
PSAT modeling and that the linear scaling used to adjust the PSAT 
results for the updated 2028 emissions inventory introduced errors into 
the modeling, EPA acknowledges that VISTAS used the original 2028 
emissions inventory to perform the PSAT modeling and that the original 
PSAT results were linearly scaled to reflect the updated 2028 
emissions. Although linear scaling introduces some uncertainty to the 
final PSAT results, EPA agrees that adjusting the results to account 
for VISTAS' updated 2028 emissions inventory using linear scaling is a 
better approach than relying on the original PSAT modeling. Linear 
scaling of photochemical modeling results to account for changes in 
emissions is an accepted practice by EPA. An example is provided by 
EPA's Modeled Emission Rates for Precursors (MERPs) for evaluating 
secondary particulate matter of 2.5 micrometers or less in diameter 
(PM2.5) impacts in Prevention of Significant Deterioration 
(PSD) modeling analyses.\27\ This guidance recommends an approach where 
the PM2.5 impacts are estimated using an archived national-
scale photochemical modeling analysis, performed using Comprehensive 
Air Quality Model with Extensions (CAMx) and Community Multiscale Air 
Quality Modeling (CMAQ) \28\ photochemical models, that uses 
hypothetical emissions sources, and then linearly scaling the 
photochemical modeling results using the ratio of the PSD project-
specific source emissions to the modeled emissions from the 
hypothetical source (see Equation 1 on page 3 of the April 30, 2024, 
MERPs memorandum). This approach is widely used and accepted by state 
air quality agencies and EPA to account for secondarily formed 
PM2.5 resulting from precursor emissions (SO2 and 
NOX) for PSD modeling analyses. Since the MERPs analyses use 
linear scaling with CAMx and for the same PM2.5 precursors 
(SO2 and NOX) as VISTAS used for their regional 
haze modeling, this example clearly shows that linear scaling of PM 
precursor emissions is an accepted practice.
---------------------------------------------------------------------------

    \27\ ``Clarification on the Development of Modeled Emission 
Rates for Precursors (MERPs) as a Tier 1 Demonstration Tool for 
Ozone and PM2.5 under the PSD Permitting Program,'' April 
30, 2024, Memorandum from Tyler Fox to Regional Office Modeling 
Contacts is available at: https://www.epa.gov/sites/default/files/2020-09/documents/epa-454_r-19-003.pdf.
    \28\ See https://www.epa.gov/cmaq for further information on 
CMAQ.
---------------------------------------------------------------------------

    Regarding the Conservation Groups' assertion that ``[n]othing in 
the SIP Revision indicates that there have been federally enforceable 
changes to the Duke Energy EGUs' operating parameters that would 
justify such large differences between recent actual emissions and 
future year 2028 projections,'' as explained in response 4.f, under the 
RHR, sources that do not meet a state's reasonable source selection 
criteria (such as these five Duke Energy EGUs) are not selected for a 
FFA and are therefore not required to have emission limits and 
supporting conditions adopted into the LTS in the SIP to support 
reasonable progress for the planning period.
    With respect to the 2028 emissions projections for the Duke Energy 
EGUs, North Carolina appears to have used the best assumptions 
available at the time of SIP development to project the 2011 base year 
emissions out to 2028 for the five Duke Energy EGUs discussed in this 
response. The State compared 2017, 2018, and 2019 actual SO2 
and NOX emissions to 2028 projected emissions in tables 7-41 
and 7-42 of their Haze Plan. The methodology used to make the 2028 
projections is discussed in appendix B-3 of North Carolina's Haze Plan. 
Table 9 in appendix B-3 provides a comparison of the different 
projection methodologies used by North Carolina including a comparison 
to the 2028 emissions projections performed separately by EPA for its 
2028 Regional Haze Modeling.\29\ The total of North Carolina's 2028 
projected SO2 emissions for the five Duke Energy EGUs in 
table 9 of appendix B-3 used for its reasonable progress and PSAT 
modeling (VISTAS 2028elv5 inventory) is 8,732 tons per year (tpy), 
which is approximately eight percent less than the 9,456 tpy of 
emissions projected by EPA for 2028 for these five sources. EPA's 2028 
emissions for EGUs were projected from the more recent 2016 base-year 
emissions inventory using the Integrated Planning Model.\30\ While 
North Carolina's 2028 projection emissions are much less than the 
recent actual emissions in 2017-2019, North Carolina's and EPA's 
projected 2028 projections are similar. Therefore, North Carolina's 
2028 emissions projections appear reasonable for the reasonable 
progress and PSAT modeling analyses.
---------------------------------------------------------------------------

    \29\ Memorandum from Richard A. Wayland to Regional Air Division 
Directors, ``Availability of Modeling Data and Associated Technical 
Support Document for EPA's Updated 2028 Visibility Air Quality 
Modeling,'' September 19, 2019, available at: https://www.epa.gov/visibility/technical-support-document-epas-updated-2028-regional-haze-modeling.
    \30\ ``Documentation for EPA's Power Sector Modeling Platform v6 
Using the Integrated Planning Model,'' November 2018, available at: 
https://www.epa.gov/power-sector-modeling/documentation-epas-power-sector-modeling-platform-v6-november-2018-reference.
---------------------------------------------------------------------------

    Comment 2.d: The Conservation Groups note that North Carolina 
relied on the PSAT modeling results for its multiple in-state sources 
that are located less than 50 kilometers (km) from a Class I area and 
claim that PSAT modeling has been shown to be unreliable for sources 
that are within a short distance from a Class I area, referencing 
Federal Land Manager (FLM) \31\ guidance that addresses

[[Page 92580]]

regional grid models. According to the Conservation Groups, this 
guidance shows that regional grid models are not preferred for sources 
located close to Class I areas and that the grid size used by VISTAS is 
too small to produce accurate results for those sources.
---------------------------------------------------------------------------

    \31\ 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.'' See 40 CFR 51.301. The 
U.S. National Park Service (NPS), U.S. Fish and Wildlife Service 
(FWS), and U.S. Forest Service (USFS) are collectively referred to 
as the ``Federal Land Managers'' or ``FLMs'' throughout this notice.
---------------------------------------------------------------------------

    Response 2.d: The Conservation Groups state that PSAT modeling has 
been shown to be unreliable for sources located less than 50 km from a 
Class I area, which caused North Carolina to inappropriately screen out 
sources which should have undergone an FFA. However, they do not 
provide any specific model performance information demonstrating that 
the CAMx model nor the PSAT source apportionment tool have poor model 
performance for evaluating visibility impacts from sources located 
within 50 km of any of the Class I areas located in North Carolina.
    Instead, the Conservation Groups provide qualitative arguments to 
support their assertion. They assert that the FLMs' Air Quality Related 
Values Work Group (FLAG) Guidance indicates that photochemical grid 
models are not the preferred model for evaluating visibility impacts 
from sources less than 50 km from Class I areas and reference the use 
of direct plume impact models. However, they are inappropriately citing 
the FLAG guidance and recommendations, which is not intended to apply 
to photochemical grid modeling or outside of the permitting context. 
The FLAG reference to direct plume models (e.g., Plume Visibility 
Model) \32\ is only for evaluating visibility impacts under the New 
Source Review (NSR)/PSD (NSR/PSD) permitting regulations and is not 
applicable to regional haze analyses. EPA's regional haze regulations 
and guidance do not require evaluations of direct plume impacts 
separate from the photochemical modeling analyses used for regional 
haze visibility analyses. Therefore, the argument is not relevant for 
the visibility analyses for regional haze.
---------------------------------------------------------------------------

    \32\ The Plume Visibility Model ``PLUVUE'' is used for 
estimating visual range reduction and atmospheric discoloration 
caused by plumes resulting from the emissions of particles, nitrogen 
oxides, and sulfur oxides from a single source. See ``PLUVUE II'' 
at: https://www.epa.gov/scram/air-quality-dispersion-modeling-alternative-models. The User's Guide is available at: https://gaftp.epa.gov/Air/aqmg/SCRAM/models/other/pluvueii/PluvueUG.pdf.
---------------------------------------------------------------------------

    The Conservation Groups also assert that since the horizontal grid 
size used in the VISTAS CAMx modeling was 12 km, it is insufficient to 
resolve the details of emissions plumes from facilities within 50 km of 
a Class I area and that the model performance degrades substantially at 
the close-in distances. The general statement from the Conservation 
Groups is that model performance substantially degrades within 50 km is 
not supported by any specific evidence in the comments. Therefore, 
North Carolina's CAMx PSAT modeling appears reasonable for selecting 
sources for reasonable progress analyses.
    The Conservation Groups separately contend that North Carolina's 
correlation analysis of the sulfate AoI versus PSAT presented in 
section 7.6.3 of the Haze Plan is flawed. They point out the scatter in 
the AoI/PSAT ratio data for distances less than 100 km in figure 7-77 
of the Haze Plan and argue this makes the State's correlation 
conclusions invalid. They also refer to the scatter in the sulfate 
fractional bias values in figure 7-78 in the Haze Plan and argue the 
AoI versus PSAT correlation is invalid. EPA disagrees. While there is 
more scatter between the data points less than 100 km from the Class I 
area, there is clearly a trend that the AoI values are much larger than 
the PSAT values within 100 km compared to the ratios for further 
distances. There is logic to this result due to the way the AoI metric 
is calculated using the Extinction Weighted Residence Times (EWRT) 
multiplied by the Emissions (Q) divided Distance (d) (EWRTxQ/d). The 
EWRT is calculated using the frequency that winds (represented by 
Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) back 
trajectories) pass over a specific geographic area (represented by a 
modeling grid cell) on the path to the Class I area.\33\ For sources 
located less than 100 km from a Class I area, there is likely to be a 
higher frequency of the HYSPLIT back trajectories passing over the 12 
km grid cell containing the source, thus the EWRT and AoI value will be 
larger. The CAMx PSAT modeling is a more refined photochemical modeling 
approach that calculates the atmospheric fate and transport of the PM 
precursors and their chemical reactions to form visibility impairing 
pollutants (e.g., ammonium sulfate). Therefore, compared to the AoI 
screening process, the refined PSAT technique is less likely to 
overestimate the visibility impacts for sources located within 100 km 
of the Class I area. Regarding the scatter of the data resulting in the 
AoI to PSAT fractional bias correlation, EPA acknowledges that there is 
scatter in the data which is reflected in the 0.72 coefficient of 
determination (R\2\) value shown in figure 7-78 in the Haze Plan. 
However, this level of correlation is not uncommon in these types of 
modeling data analyses, and the results are reasonable. For these 
reasons, North Carolina's correlation approach appears valid.
---------------------------------------------------------------------------

    \33\ See section 7.5 of the Haze Plan for additional detail.
---------------------------------------------------------------------------

    The photochemical modeling employed by VISTAS and North Carolina is 
the most refined methodology available for evaluating regional haze 
visibility impacts. Moreover, North Carolina's AoI screening process 
identified sources located within 50 km of its Class I areas, including 
the BRPP facility located approximately 17 km from Swanquarter that met 
the PSAT source selection criteria and underwent an FFA to evaluate 
reasonable progress. As discussed above, North Carolina demonstrated in 
section 7.6.3 of the Haze Plan that the AoI screening technique tends 
to overestimate visibility impacts for sources located within 100 km of 
a Class I area. Based upon this AoI overestimation, in section 7.7.3 of 
the Haze Plan, North Carolina explains why some sources located less 
than 100 km from its Class I areas were not tagged for PSAT modeling 
and thus were not selected for FFAs. North Carolina's justification 
regarding why the other sources within 100 km were not selected for 
FFAs appears reasonable.
    Comment 2.e: The Conservation Groups claim that North Carolina did 
not justify its application of the one percent PSAT threshold and that 
North Carolina's use of this threshold at the PSAT step biased the 
process against heavily polluted Class I areas. They note that NPS' 
comments on the draft SIP revision explain that reliance on the 
percent-based threshold required source impacts to be 80 times larger 
for the most visually impaired Class I areas versus the least visually 
impaired Class I areas in order to be selected for an FFA. They also 
argue that PSAT tagging was unnecessary because the AoI step already 
identified the sources that contributed to impairment at Class I areas.
    Response 2.e: EPA disagrees with the Conservation Groups' assertion 
that North Carolina did not justify its application of the one percent 
PSAT threshold. Section 7.7.1 of the Haze Plan explains the State's 
rationale for using a one percent PSAT threshold to select sources for 
a reasonable progress evaluation. Using a percentage-based threshold 
enabled the State to identify

[[Page 92581]]

the sources that contribute the largest amount of impact on visibility 
at the Class I areas. While it is true that using a one percent PSAT 
threshold identifies sources which contribute larger visibility impacts 
at the most visually impaired Class I areas than at the least visually 
impaired Class I areas, North Carolina's targeting of sources with the 
largest visibility contributions to each Class I area regardless of 
magnitude of visibility impairment at a Class I area appears 
reasonable. Use of a percentage-based threshold produced a relative 
ranking of visibility impairment to allow the State to focus on the 
sources contributing to the largest amount of visibility impact at each 
individual Class I area, which has the potential to reduce visibility 
impacts the most. Regardless of whether a relative or absolute 
threshold is used, the number of sources selected depends on the chosen 
value of the threshold. North Carolina's source contribution threshold, 
which identified the largest sources to evaluate emissions measures 
using an FFA, appears reasonable.
    Regarding the Conservation Groups' assertion that the PSAT tagging 
process was unnecessary, as the AoI step already identified the sources 
that contributed to impairment at Class I areas, EPA disagrees with the 
premise of this comment. The standard is not whether the approach is 
necessary or required, but rather, whether the approach is reasonable 
and is reasonably explained.\34\ The two-step process of screening with 
the AoI analysis and then applying the more refined PSAT source 
apportionment modeling to sources that met the initial AoI screening 
criteria is a sound technical approach for identifying sources to 
evaluate for reasonable progress. Elements of North Carolina's AoI 
approach are discussed in EPA's 2019 Guidance as a viable method to 
assess source's visibility impacts to Class I areas.\35\ North 
Carolina, along with many of the VISTAS states, also relied upon the 
AoI initial screening approach in its first planning period haze 
plan.\36\ VISTAS used the AoI analysis as an initial screening step 
because it is a much simpler and less resource intensive approach than 
using PSAT tagging to model hundreds to thousands of potential sources. 
The AoI screening approach identified a smaller subset of sources that 
could undergo refined analysis using PSAT modeling. The two-step 
process of the screening AoI analysis along with using the more refined 
PSAT source apportionment modeling appears valid and reasonable. Also, 
as discussed above, states have discretion under the RHR regarding 
choice of source selection methodology.
---------------------------------------------------------------------------

    \34\ See 40 CFR 51.308(f)(2)(i), (iii); see also sections 2 and 
2.1 of 2021 Clarifications Memo.
    \35\ EPA's 2019 Guidance at pp. 12-14 describes components of 
North Carolina's AoI approach, including Q/d, trajectory analyses, 
residence time analyses, and source apportionment photochemical 
modeling (e.g., CAMx PSAT).
    \36\ See, e.g., 77 FR 11858, 11869 (February 28, 2012) for a 
description of North Carolina's AoI approach in the first planning 
period. On May 24, 2016, EPA fully approved North Carolina's first 
period regional haze plan, effective June 23, 2016. See 81 FR 32652.
---------------------------------------------------------------------------

    Comment 2.f: The Conservation Groups contend that EPA did not 
address the ``significant flaws'' in the VISTAS modeling and source 
selection process and that EPA concluded that North Carolina's 
selection of three in-state sources was reasonable because it enabled 
the identification of sources with the largest visibility impacts. They 
argue that this is contrary to EPA's guidance which states that a 
source selection threshold that captures only a small portion of a 
state's contribution to visibility impairment in Class I areas is more 
likely to be unreasonable and contrary to the CAA which does not 
authorize states or EPA to select only the largest contributors to 
visibility impairment. They assert that North Carolina should have used 
a different selection method with a lower threshold, such as a ``Q/d'' 
(emissions (Q) divided by distance to a Class I area (d)) with a 
threshold of five or lower, to capture the largest portion of in-state 
sources.
    Response 2.f: EPA disagrees with the assertion that North 
Carolina's selection of the three largest sources contributing to 
visibility impairment at Class I areas is contrary to EPA's guidance. 
The PSAT modeling performed by VISTAS found that the three sources 
selected by North Carolina for FFAs have the largest contribution to 
visibility impairment of any point sources in the State. As discussed 
in response 2.a., the PSAT modeling results show that the total 
cumulative contribution to visibility impairment on the 20 percent most 
impaired days at North Carolina's Class I areas from all SO2 
and NOX emitting sources in the State are relatively small, 
ranging from 1.91 percent for Joyce Kilmer to 8.66 percent for 
Swanquarter. Given state discretion in selecting sources to evaluate 
for emissions controls, and since the SO2 and NOX 
emissions from all point sources in North Carolina contribute a 
relatively small amount to the visibility impairment at its Class I 
areas, the State's selection of the three largest source contributors 
to visibility impairment appears reasonable.
    Regarding the Conservation Groups' claim that the State should have 
adopted a different selection method (such as Q/d) with a lower 
threshold to select more sources in North Carolina being selected, as 
discussed above, a state is not required to evaluate all sources of 
emissions in each planning period. Instead, a state may reasonably 
select a set of sources for an analysis of control measures. Selecting 
a set of sources for analysis of control measures in each planning 
period is also consistent with the RHR, 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.\37\ 
Moreover, use of Q/d (which simply involves dividing the quantity of 
emissions by the distance to a Class I area) does not consider 
transport direction/pathway, dispersion and photochemical processes, or 
the particular days that have the most anthropogenic impairment due to 
all sources.\38\ Therefore, compared to photochemical modeling, using a 
simple Q/d technique, as the Conservation Groups suggest, would have 
resulted in a less accurate quantification of visibility impacts on 
Class I areas. As discussed in detail above, North Carolina's reliance 
on VISTAS modeling and the State's source selection methodology were 
well documented and appear reasonable.
---------------------------------------------------------------------------

    \37\ See 2019 Guidance at 9.
    \38\ See 2019 Guidance at 13.
---------------------------------------------------------------------------

    Comment 2.g: The Conservation Groups state that EPA asserts North 
Carolina's source selection method is reasonable because: (1) 
SO2 and NOX emissions have decreased since the 
first planning period and are projected to continue decreasing, (2) 
visibility conditions at in-state Class I areas are projected to 
improve and have improved since the baseline period, and (3) North 
Carolina sources do not contribute to any Class I areas above their 
respective Uniform Rate of Progress (URP). They argue that projected 
visibility improvement at North Carolina's Class I areas and the fact 
that those areas are below their respective URPs are not a valid basis 
to approve the State's flawed selection method. They cite to EPA 
guidance stating that the URP is not a safe harbor and that states 
cannot avoid requiring sources to install reasonable controls merely 
because there have been emissions reductions owing to ongoing air 
pollution controls since the first planning period or because 
visibility is projected to improve at Class I areas.

[[Page 92582]]

    Response 2.g: EPA agrees that the URP is not a ``safe harbor'' to 
avoid requiring additional reasonable progress measures. However, 
factual information that all of the North Carolina and nearby Class I 
areas are below the URP was provided because being below the URP is 
relevant to whether a state needs to perform a ``robust demonstration'' 
based on the requirements in 40 CFR 51.308(f)(3)(ii)(A) and (B). 
Therefore, a comparison of the URP to projected visibility impairment 
in 2028 is needed to inform that requirement. Additionally, other 
information about measured progress towards natural conditions can be 
relevant in evaluating the source selection process. For example, 
significant improvements in visibility at impacted Class I areas since 
the beginning of the second planning period (starting in 2018) is 
relevant to whether a state is making progress towards natural 
conditions and may provide information that could influence the 
selection of sources to be analyzed for emissions controls in the 
second planning period. Regardless of the visibility information listed 
in the proposed rule, EPA independently evaluated North Carolina's SIP 
documentation and came to the conclusion that North Carolina's source 
selection methodology and thresholds for this second planning period 
appear reasonable for the reasons stated earlier in this response.
    For the reasons discussed in responses 2.a through 2.g, North 
Carolina's source selection methodology appears reasonable. However, 
the requirement to consider the four factors in establishing the LTS at 
40 CFR 51.308(f)(2) and CAA section 169A(g)(1) encompasses the 
selection of sources for further analysis, and as discussed above, EPA 
is disapproving the portions of the Haze Plan addressing 40 CFR 
51.308(f)(2) due to the inadequate record associated with the Domtar 
FFA.
    Comment 3: The Conservation Groups assert that EPA incorrectly 
endorses North Carolina's decision to exclude consideration of 
NOX controls in any FFAs. They contend that VISTAS' modeling 
did not accurately reflect the shift in the 20 percent most impaired 
days and the corresponding increase in the contribution of nitrate to 
visibility impairment at Southeastern Class I areas. They state that 
nitrate concentrations are higher on winter days, nitrate contributes 
to a substantial portion of light extinction at Great Smoky Mountains 
and Joyce Kilmer, and nitrate is the biggest contributor to light 
extinction on multiple 20 percent most impaired days for these areas. 
They also note EPA's general expectation that states will, at a 
minimum, consider both SO2 and NOX in this 
planning period, and assert that there are multiple sources of 
significant NOX emissions that North Carolina should have 
analyzed for NOX controls.
    Response 3: EPA disagrees with this comment. The RHR does not 
prescribe which visibility impairing pollutants must be evaluated in 
the FFAs. EPA's 2019 Guidance on page 11 states: ``When selecting 
sources for analysis of control measures, a state may focus on the PM 
species that dominate visibility impairment at the Class I areas 
affected by emissions from the state and then select only sources with 
emissions of those dominant pollutants and their precursors.'' On July 
8, 2021, EPA issued a memorandum containing ``Clarifications Regarding 
Regional Haze State Implementation Plans for the Second Implementation 
Period'' (``2021 Clarifications Memo'').\39\ Section 2.2 of EPA's 2021 
Clarifications Memo recommends that states which do not evaluate 
SO2 and NOX in both source selection and control 
evaluations show why such consideration of these pollutants would be 
unreasonable, especially if the state considered both of these 
pollutants in the first planning period.\40\
---------------------------------------------------------------------------

    \39\ ``Clarifications Regarding Regional Haze State 
Implementation Plans for the Second Implementation Period.'' https://www.epa.gov/system/files/documents/2021-07/clarifications-regarding-regional-haze-state-implementation-plans-for-the-second-implementation-period.pdf. EPA Office of Air Quality Planning and 
Standards, Research Triangle Park (July 8, 2021).
    \40\ North Carolina considered SO2 for FFAs conducted 
in the first planning period.
---------------------------------------------------------------------------

    North Carolina appears to have followed these recommended 
approaches here. North Carolina considered both SO2 
emissions (via sulfates visibility impacts) and NOX 
emissions (via nitrates visibility impacts) in the source selection 
process. As part of the Haze Plan, DAQ presented the results of PSAT 
modeling conducted by VISTAS to estimate the projected impact of 
statewide SO2 and NOX emissions across all 
emissions sectors in 2028 on total light extinction for the 20 percent 
most impaired days in all Class I areas in the VISTAS modeling domain. 
The result of this process was that while sources were selected for 
SO2 control analysis determinations, no sources in North 
Carolina met the State's nitrate source selection thresholds, and 
therefore, North Carolina did not select any sources for a 
NOX emissions control evaluation. Contrary to the 
Conservation Groups' assertion that North Carolina made a ``decision'' 
not to consider NOX controls in any FFA, it was North 
Carolina's application of its source selection process in combination 
with data and modeling showing that SO2 and not 
NOX is the dominant visibility impairing pollutant that 
resulted in North Carolina only selecting sources for SO2 
emissions control analyses and not NOX emissions control 
analyses.
    Additionally, in order to better understand the trends in PM 
species contributions to visibility impairment, North Carolina examined 
more recent IMPROVE monitoring data. More recent IMPROVE monitoring 
data shows that ammonium sulfate remains the dominant visibility 
impairing pollutant at North Carolina's Class I areas as discussed in 
section 2.5.2 of the Haze Plan (particularly figures 2-7 through 2-10 
for the 2009-2013 period) and in section 2.6.2 (particularly figures 2-
13 through 2-16 for the 2014-2018 period). The 2015-2019 IMPROVE 
monitoring data (the most recent data available at the time) cited 
within the Haze Plan (figures 10-1, 10-2, and 10-3) identifies the 
relative contributions of PM species contributing to the total 
visibility impairment at the North Carolina Class I areas, which are 
shown in table 2, below. In spite of increased nitrate contributions on 
the 20 percent most impaired days (as the Conservation Groups note, 
often on winter days), as indicated in that table, ammonium nitrate 
contributions to regional haze at the State's Class I areas remain 
relatively low at 8 to 17 percent of the total visibility impairment as 
compared to ammonium sulfate at 50 to 58 percent.

[[Page 92583]]

                                 Table 2--2015-2019 Speciated IMPROVE Monitoring Data for North Carolina's Class I Areas
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     Ammonium     Ammonium     Organic     Coarse     Elemental    Fine sea   Fine soils
                                                                   sulfate (%)  nitrate (%)  carbon (%)   mass (%)    carbon (%)   salt (%)       (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Great Smoky Mountains............................................           54           17          17           5            6           1           1
Joyce Kilmer.....................................................           54           17          17           5            6           1           1
Linville Gorge...................................................           57            8          22           5            7           0           1
Shining Rock.....................................................           58           10          19           5            5           1           1
Swanquarter......................................................           50           17          17           7            5           3           1
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Additionally, in figure 10-7 of the Haze Plan, North Carolina 
provides a comparison of the sulfate and nitrate five-year averages for 
the 2009-2013 and 2015-2019 periods for all the Class I areas in the 
VISTAS region. North Carolina's conclusion that although nitrate 
contributions have increased for some Class I areas, sulfate remains 
the dominant visibility impairing species through 2019, appears 
reasonable.
    Furthermore, in tables 7-20 through 7-24 of the Haze Plan, the 
State provided a calculation of the sulfate and nitrate EWRT used in 
the AoI analysis for Great Smoky Mountains, Joyce Kilmer, Linville 
Gorge, Shining Rock, and Swanquarter for the 20 percent most impaired 
days, demonstrating that the sulfate EWRT are significantly higher than 
the nitrate EWRT. This further supports the importance of focusing on 
SO2 emissions reductions for this planning period. The 
State's rationale for focusing on SO2 controls in the FFAs 
is summarized in North Carolina's SIP submittal and the NPRM.\41\
---------------------------------------------------------------------------

    \41\ See Haze Plan, section 2 (particularly figures 2-13 through 
2-18), section 7 (particularly figures 7-25 through 7-31), and 
section 10 (particularly figures 10-1 through 10-7); 89 FR 67353-54.
---------------------------------------------------------------------------

    With respect to the Conservation Groups' assertion that nitrate is 
the biggest contributor to light extinction on multiple of the 20 
percent of most impaired days for these North Carolina Class I areas 
during the 2014-2018 period (especially on winter days), as described 
above, the average nitrate contribution across the 20 percent most 
impaired days is still relatively small. Thus, while nitrate impairment 
may be relatively high on a particular day, the data that states are 
required to use for regional haze as specified in 40 CFR 51.301 and 40 
CFR 51.308(f)(1) shows ammonium nitrate only contributes 8 to 17 
percent of the total visibility impairment (during the 2015-2019 
period).
    North Carolina's justification for not evaluating sources selected 
for SO2 emission control analyses for a separate 
NOX emission control analysis appears reasonable for this 
planning period. The trends in PM species' contributions to visibility 
impairment will continue to be evaluated in future planning periods. If 
the data warrants consideration of NOX controls in future 
planning periods, EPA expects that North Carolina will address 
potential NOX controls in future regional haze SIP 
revisions. However, the requirement to consider the four factors in 
establishing the LTS at 40 CFR 51.308(f)(2) and CAA section 169A(g)(1) 
encompasses decisions regarding the visibility impairing pollutants 
evaluated in the FFAs, and as discussed above, EPA is disapproving the 
portions of the Haze Plan addressing 40 CFR 51.308(f)(2) due to the 
inadequate record associated with the Domtar FFA.
    Comment 4: The Conservation Groups assert that, to correct errors 
in the source selection method, EPA must require North Carolina to 
assess additional EGU sources identified by NPS and NPCA with emissions 
that likely contribute to visibility impairment at Class I areas. The 
Conservation Groups argue that the State arbitrarily refused to 
consider cost-effective control efficiency improvements at each Duke 
Energy EGU and identify specific concerns for DEC--Belews Creek, DEC--
Cliffside, DEC--Marshall, and DEP--Roxboro.\42\ They contend that EPA 
must disapprove the State's reliance on unenforceable emission 
reductions to avoid conducting FFAs at these EGUs, and that EPA must 
disapprove the State's refusal to conduct FFAs for sources that the 
State's analysis shows are reasonably anticipated to contribute to 
visibility impairment. These specific arguments are addressed in 
comments 4.a through 4.g, below.
---------------------------------------------------------------------------

    \42\ The Conservation Groups' letter identifies five Duke Energy 
EGUs on pages iv and 46 and identifies four Duke Energy EGUs in the 
Table of Contents on page v and in sections III.D.1.i-iv of the 
letter. The five Duke Energy EGUs listed on pages iv and 46 that the 
Conservation Groups recommend to be evaluated for emissions controls 
are: DEC--Belews Creek, DEC--Cliffside, DEC--Marshall, DEP--Roxboro, 
and DEP--Mayo. Sections III.D.1.i-iv do not include recommendations 
regarding improved control efficiencies specific to DEP-Mayo.
---------------------------------------------------------------------------

    Comment 4.a: The Conservation Groups contend that states must 
consider recent actual and projected emission rates to determine if a 
source could reasonably attain a lower rate with existing measures. For 
DEC--Belews Creek, DEC--Cliffside, DEC--Marshall, and DEP--Roxboro, the 
Conservation Groups assert errors in North Carolina's analysis of 
potential emission reductions for NOX and SO2 and 
that, in each instance, EPA must disapprove the State's analysis, 
conduct its own FFA, and require cost effective control upgrades in a 
FIP.\43\ The alleged errors for these four facilities are addressed in 
comments 4.b through 4.e, below.
---------------------------------------------------------------------------

    \43\ The Conservation Groups provide the following information 
for these four Duke Energy EGUs: DEC--Belews Creek contributes to up 
to 2.01 percent of the sulfate plus nitrate impairment at Linville 
Gorge and up to 1.56 percent of the sulfate plus nitrate impairment 
at Shining Rock; DEC--Cliffside contributes to up to 1.85 percent of 
the sulfate plus nitrate impairment at Shining Rock and 2.49 percent 
at Linville Gorge; DEC--Marshall contributes to up to 6.73 percent 
of the sulfate plus nitrate impairment at Linville Gorge and up to 
2.68 percent of the sulfate plus nitrate impairment at Shining Rock; 
and DEP--Roxboro contributes to up to 2.23 percent of the sulfate 
plus nitrate impairment at Swanquarter.
---------------------------------------------------------------------------

    Response 4.a: As explained in response 2.a and in the NPRM (89 FR 
67346), the RHR does not require states to select and consider controls 
for all sources, all source categories, or any or all sources in a 
particular source category. Nor does the RHR expressly specify criteria 
for minimum source selection thresholds. States have discretion to 
choose reasonable source selection criteria, and sources that meet the 
state's criteria are selected for an evaluation of potential control 
options for specific visibility impairing pollutants by applying the 
four statutory factors in CAA section 169A(g)(1), which is referred to 
as an FFA.
    The Conservation Groups contend that DEC--Marshall exceeded the AoI 
threshold set by North Carolina, but EPA notes that no Duke Energy EGU 
exceeded the State's PSAT threshold at any Class I area. Therefore, 
North Carolina did not evaluate any Duke Energy EGU for potential 
emissions

[[Page 92584]]

controls. This approach is consistent with the State's source selection 
results summarized in tables 7-30 through 7-35,\44\ and North 
Carolina's decision not to assess Duke Energy EGUs for control 
efficiency improvements because they did not meet the State's source 
selection criteria appears reasonable.
---------------------------------------------------------------------------

    \44\ Table 7-29 of the Haze Plan lists facilities that met North 
Carolina's AoI threshold and thus were selected by the State for 
PSAT tagging. Tables 7-30 through 7-35 provide PSAT results for the 
North Carolina Class I areas.
---------------------------------------------------------------------------

    As described in the 2019 Guidance,\45\ North Carolina completed an 
additional reasonableness check on their source selection process by 
examining the unselected sources to see if there were any 
``uncontrolled or lightly controlled facilities that were large 
contributors to anthropogenic light extinction,'' and found none.\46\ 
In the NPRM (89 FR 67359), EPA documented an analysis that further 
examined the Duke Energy sources to verify North Carolina's claim that 
there were no uncontrolled or lightly controlled sources that were not 
selected. EPA evaluated the existing SO2 controls at DEC--
Belews Creek, DEC--Cliffside, DEC--Marshall, DEP--Mayo, and DEP--
Roxboro. EPA analyzed whether these EGUs are well controlled for 
SO2 and whether any cost-effective new emissions reduction 
measures for SO2 would have likely resulted from a FFA had 
these sources met the State's source selection criteria.\47\ Based on 
that analysis, it appears reasonable to assume that a FFA would likely 
result in the conclusion that no further SO2 emissions 
controls are needed for these sources. All of these EGUs are subject to 
the Mercury and Air Toxics Standards (MATS) rule \48\ alternative 
SO2 emission limit of 0.2 pound (lb)/million British thermal 
units (MMBtu) and are equipped with wet flue gas desulfurization (WFGD) 
that routinely achieve a high SO2 control effectiveness 
(approximately 93.8-99.2 percent).\49\ EPA did not evaluate 
NOX controls for these EGUs because North Carolina's 
conclusion that ammonium sulfate continues to be the dominant 
visibility impairing pollutant at North Carolina's Class I areas 
appears reasonable. See section IV.C.2.a of the NPRM and response 3.
---------------------------------------------------------------------------

    \45\ See 2019 Guidance at p. 19 (``For example, it may be 
difficult to show reasonableness of a threshold set so high that an 
uncontrolled or lightly controlled source that is one of the largest 
contributors to anthropogenic light extinction at a Class I area is 
excluded.'').
    \46\ See Haze Plan at p. 251.
    \47\ Between the years 2017-2022, the calculated annual FGD 
SO2 control efficiencies for DEP--Mayo Unit 1A were 
between 96.3 and 97.9 percent.
    \48\ The MATS rule is located at 40 CFR part 63, subpart UUUUU.
    \49\ See North Carolina Duke Energy scrubber efficiency data 
file that is included in the docket for this action. See also 89 FR 
67359; 2019 Guidance at 23.
---------------------------------------------------------------------------

    Comment 4.b: The Conservation Groups argue that North Carolina's 
analysis of potential emission reductions for DEC--Marshall suffer from 
the following errors regarding SO2: (1) the wet scrubbers 
are operated erratically; (2) the units have the ability to 
continuously operate well below 0.10 lb/MMBtu for SO2; (3) 
``EPA has concluded that underperforming wet scrubbers should be 
evaluated at 98 percent control (with a floor of 0.04 lb/MMBtu), and 95 
percent control (with a floor of 0.06 lb/MMBtu) for dry scrubbers;'' 
(4) ``even lower limits can be achieved;'' and (5) ``Without any 
capital upgrade cost (and likely minimal operating and maintenance 
costs) the DEC-Marshall units are likely quite capable of much better 
SO2 and NOX removal efficiencies that could 
likely be achieved with cost-effective upgrades.'' They also argue that 
North Carolina's analysis of potential NOX emission 
reductions suffer from the following errors: (1) ``Units 1, 2, and 4 
are equipped with selective non-catalytic reduction (SNCR) systems that 
have achieved lower NOX emission levels of approximately 
0.20 lb/MMBtu, `with some months significantly below that level;' '' 
(2) the selective catalytic reduction (SCR) system for Unit 3 is 
``operated very erratically, but has demonstrated the ability from 
2010-2011 to consistently operate below 0.05 lbs/MMBtu;'' and (3) 
``Without any capital upgrade cost (and likely minimal operating and 
maintenance costs) the DEC--Marshall units are quite capable of much 
better NOX removal efficiencies with likely cost-effective 
upgrades.
    Response 4.b: Regarding potential NOX control upgrades 
at DEC--Marshall, North Carolina's decision to focus on SO2 
emission controls in the second planning period appears reasonable 
given the documented dominance of sulfate contributions to visibility 
impairment at North Carolina's Class I areas. See section IV.C.2.a of 
the NPRM and response 3. Thus, it appears reasonable to conclude that 
even if DEC--Marshall had met the State's source selection criteria, no 
NOX emissions control analyses would be necessary for 
reasonable progress during this planning period. Additionally, North 
Carolina did not select this facility, and therefore, no FFA 
information is available. However, EPA's analysis confirms that the 
units are not uncontrolled or lightly controlled, are subject to the 
MATS rule alternative SO2 emission limit of 0.2 lb/MMBtu, 
and are equipped with WFGD that routinely achieve a high SO2 
control effectiveness (approximately 93.8 to 97.9 percent).\50\
---------------------------------------------------------------------------

    \50\ Between 2017 to 2022, the yearly average FGD SO2 
control efficiencies for Unit 1 ranged from 94.7 to 96.2 percent, 
Unit 2 ranged from 93.8 to 96.1 percent, Unit 3 ranged from 95.2 to 
97.1 percent, and Unit 4 ranged from 96.7 to 97.9 percent. See North 
Carolina Duke Energy scrubber efficiency data file that is included 
in the docket for this action.
---------------------------------------------------------------------------

    Comment 4.c: The Conservation Groups argue that North Carolina's 
analysis of potential emission reductions at DEC--Belews Creek suffer 
from the following errors regarding SO2: (1) the wet 
scrubbers ``are underperforming, with emission rates, at times, spiking 
above 0.30 lb/MMBtu;'' (2) the scrubbers ``have demonstrated the 
capability to consistently control SO2 to 0.05 lbs/MMBtu or 
better on a monthly average basis for both units;'' (3) ``[s]imply 
increasing the amount of reagent used would be very cost-effective, 
require little or no capital investments, and would likely achieve much 
lower emissions;'' and (4) the ``assumption that SO2 
emissions will be reduced from 4,946 to 1,385 tons annually is not 
supported in the record, and not based on any enforceable 
requirement.'' They also argue that North Carolina's analysis of 
potential emission reductions suffer from the following errors 
regarding NOX: (1) the ``2028 NOX emission 
projections for Belews Creek are significantly less than the facility 
has emitted in recent years, yet there are no enforceable emission 
limitations in the SIP Revision that would ensure those 2028 
estimates;'' (2) the ``SCR systems perform erratically, with emissions 
above 0.40 lb/MMBtu at times;'' (3) ``Belews Creek could likely achieve 
NOX emission rates of 0.05 lbs/MMBtu or better on a 
consistent basis with better catalyst and absorber management;'' and 
(4) ``[s]imple upgrades to the SCR system would likely be cost-
effective.''
    Response 4.c: Regarding potential NOX control upgrades 
at DEC--Belews Creek, North Carolina's decision to focus on 
SO2 emission controls in the second planning period appears 
reasonable given the documented dominance of sulfate contributions to 
visibility impairment at North Carolina's Class I areas. See section 
IV.C.2.a of the NPRM and response 3. Thus, it appears reasonable to 
conclude that even if DEC--Belews Creek had met the State's source 
selection criteria, no NOX emissions control analyses would 
be warranted.
    Regarding the original and revised 2028 SO2 emissions 
projections of 4,946 tpy and 1,385 tpy, respectively, for

[[Page 92585]]

DEC--Belews Creek listed in table 7-41 of the Haze Plan, as explained 
in responses 1 and 2.c, North Carolina used the best assumptions 
available at the time of SIP development to project the 2011 base year 
emissions out to 2028 for sources in the State, including DEC--Belews 
Creek. North Carolina did document its 2028 point source emissions 
projection methodology in appendix B-3 of the Haze Plan. Table 9 in 
appendix B-3 shows that the 1,385 tpy 2028 projected SO2 
value in table 7-41 of the plan is from a blend of two versions (2.7 
and 16.0) of the Eastern Regional Technical Advisory Committee (ERTAC) 
EGU Emissions Projection Tool \51\ that was used to create the VISTAS 
2028elv5 emissions inventory. As stated in response 2.c, North 
Carolina's and EPA's projected 2028 emissions projections, summarized 
in appendix B-3 of the Haze Plan, are similar. Therefore, North 
Carolina's 2028 SO2 emissions projections for DEC--Belews 
Creek appear to be reasonable estimates.
---------------------------------------------------------------------------

    \51\ See https://www.epa.gov/air-emissions-inventories/eastern-regional-technical-advisory-committee-ertac-electricity.
---------------------------------------------------------------------------

    Additionally, North Carolina did not select this facility, and 
therefore, no FFA information is available. However, EPA's analysis 
confirms that the units are not uncontrolled or lightly controlled, are 
subject to the MATS rule alternative SO2 emission limit of 
0.2 lb/MMBtu, and are equipped with WFGD that routinely achieve a high 
SO2 control effectiveness (approximately 94.1 to 96.5 
percent).\52\
---------------------------------------------------------------------------

    \52\ Between 2017 to 2022, the yearly average FGD SO2 
control efficiencies for Unit 1 ranged from 94.1 to 96.5 percent and 
Unit 2 ranged from 95.0 to 96.2 percent. See North Carolina Duke 
Energy scrubber efficiency data file that is included in the docket 
for this action.
---------------------------------------------------------------------------

    Comment 4.d: The Conservation Groups argue that North Carolina's 
analysis of potential emission reductions for DEP--Roxboro suffer from 
the following errors regarding SO2: (1) the ``projections 
for 2028 SO2 are not based on historical data, but instead 
rely on unenforceable, predicted emission reductions, from 6,665 in 
2020, to 2,258 tons in 2028;'' (2) the wet scrubbers ``are 
underperforming with emissions as high as 0.35 lb/MMBtu;'' (3) the 
scrubbers ``have `demonstrated the capability to consistently control 
SO2 to approximately 0.075 lb/MMBtu or better on a monthly 
average;' '' and (4) there are ``likely very cost-effective scrubber 
upgrades available.'' They also argue that North Carolina's analysis of 
potential emission reductions suffer from the following errors 
regarding NOX: (1) the ``projections for 2028 NOX 
emissions are not based on historical data, but instead rely on 
unenforceable, predicted emission reductions;'' (2) the ``SCR systems 
perform erratically, with emissions sometimes spiking to nearly 0.5 lb/
MMBtu, which is far worse than the rates commonly achievable and 
required of well-functioning SCR systems;'' (3) the ``SCR systems have 
`all have demonstrated the ability to continuously operate at 
approximately 0.10 lbs/MMBtu;' '' and (4) there are ``likely very cost-
effective control upgrades available.''
    Response 4.d: Regarding potential NOX control upgrades 
and SCR performance at DEP--Roxboro, North Carolina's decision to focus 
on SO2 emission controls in the second planning period 
appears reasonable given the documented dominance of sulfate 
contributions to visibility impairment at North Carolina's Class I 
areas. See section IV.C.2.a of the NPRM and response 3. Thus, it 
appears reasonable to conclude that even if DEP--Roxboro had met the 
State's source selection criteria, no NOX emissions control 
analyses would be warranted.
    Regarding the original and revised 2028 SO2 emissions 
projections of 6,665 tpy and 2,258 tpy, respectively, for DEP--Roxboro 
listed in table 7-41 of the Haze Plan, as explained in responses 1 and 
2.c, North Carolina used the best assumptions available at the time of 
SIP development to project the 2011 base year emissions out to 2028 for 
sources in the State, including DEP--Roxboro. North Carolina did 
document its 2028 point source emissions projection methodology in 
appendix B-3 of the Haze Plan. Table 9 in appendix B-3 shows a 2028 
projection of 6,666 tpy SO2 for DEP--Roxboro is derived from 
ERTAC2.7 (2011 base year) whereas the VISTAS 2028 elv5 uses a 2,258 tpy 
SO2 2028 emissions projection. As stated in response 2.c, 
North Carolina's and EPA's projected 2028 emissions projections, 
summarized in appendix B-3 of the Haze Plan, are similar. Therefore, 
North Carolina's 2028 SO2 emissions projections for DEP--
Roxboro appear to be reasonable estimates.
    Additionally, North Carolina did not select this facility, and 
therefore, no FFA information is available. However, EPA's analysis 
confirms that the units are not uncontrolled or lightly controlled, are 
subject to the MATS rule alternative SO2 emission limit of 
0.2 lb/MMBtu, and are equipped with WFGD that routinely achieve a high 
SO2 control effectiveness (approximately 94.3 to 98.8 
percent).\53\
---------------------------------------------------------------------------

    \53\ Between 2017 to 2022, the yearly average FGD SO2 
control efficiencies for Unit 1 ranged from 95.9 to 97.1 percent, 
Unit 2 ranged from 94.3 to 96.6 percent, Unit 3A ranged from 98.2 to 
98.8 percent, and Unit 4A ranged from 97.1 to 98.3 percent. See 
North Carolina Duke Energy scrubber efficiency data file that is 
included in the docket for this action.
---------------------------------------------------------------------------

    Comment 4.e: The Conservation Groups argue that North Carolina's 
analysis of potential emission reductions from DEC--Cliffside suffer 
from the following errors regarding SO2: (1) the ``scrubber 
performance is erratic, with SO2 spikes at Unit 5 
periodically exceeding 0.35 lb/MMBtu;'' (2) ``Nevertheless, each of the 
scrubbers have demonstrated an ability to consistently achieve 
SO2 emissions of 0.04 lb/MMBtu;'' and (3) `` `[V]ery cost-
effective controls are available for these units for likely just the 
increase in reagent,' yet the State failed to even consider such 
upgrades.'' They also argue that North Carolina's analysis of potential 
emission reductions suffer from the following errors regarding 
NOX: (1) the ``SCR systems are similarly irregular, with 
spikes at Unit 5 exceeding 0.30 lb/MMBtu NOX;'' (2) the 
``SCR systems have demonstrated an ability to consistently achieve 
NOX emissions of 0.05 lb/MMBtu;'' and (3) ``Cost-effective 
improvements, such as optimizing the catalyst controls would likely be 
very cost-effective, but the State failed to even run such cost 
calculation.''
    Response 4.e: Regarding potential NOX control upgrades 
and SCR performance at DEC--Cliffside, North Carolina's decision to 
focus on SO2 emission controls in the second planning period 
appears reasonable given the documented dominance of sulfate 
contributions to visibility impairment at North Carolina's Class I 
areas. See section IV.C.2.a of the NPRM and response 3. Thus, it 
appears reasonable to conclude that even if DEC--Cliffside had met the 
State's source selection criteria, no NOX emissions control 
analyses would be warranted. Additionally, North Carolina did not 
select this facility, and therefore, no FFA information is available. 
However, EPA's analysis confirms that the units are not uncontrolled or 
lightly controlled, are subject to the MATS rule alternative 
SO2 emission limit of 0.2 lb/MMBtu, and are equipped with 
WFGD that routinely achieve a high SO2 control effectiveness 
(96.2 to 99.2 percent).\54\
---------------------------------------------------------------------------

    \54\ Between 2017 to 2022, the yearly average FGD SO2 
control efficiencies for Unit 5 ranged from 96.2 to 98.6 percent and 
Unit 6 ranged from 98.0 to 99.2 percent. See North Carolina Duke 
Energy scrubber efficiency data file that is included in the docket 
for this action.

---------------------------------------------------------------------------

[[Page 92586]]

    Comment 4.f: The Conservation Groups assert that EPA must 
disapprove North Carolina's reliance on unenforceable, hypothetical 
emission reductions for the Duke Energy EGUs to avoid conducting 
control analyses, to demonstrate reasonable progress, and to achieve 
the State's reasonable progress goals (RPGs). They note that the CAA 
and RHR require the Haze Plan to include enforceable limitations and 
other control measures to meet the RPGs for each Class I area and that 
EPA has made it clear that, to the extent that a state declines to 
evaluate pollution controls to reduce haze for any source based on that 
source's planned decline in utilization or reductions in emissions, it 
must incorporate those operating parameters or assumptions as 
enforceable limitations into the SIP.
    The Conservation Groups disagree with North Carolina's statement 
that the ``obligation to make reductions permanent and enforceable does 
not extend to any control or emissions reduction determination outside 
of the reasonable progress/four-factor analysis.'' The Conservation 
Groups state that the requirement to ensure that emission reductions 
are enforceable stems from the CAA and the RHR itself and quote the 
2021 Clarification Memo for the proposition that existing and ``on-the-
way'' measures must be included in the SIP if they are necessary for 
reasonable progress. The Conservation Groups also contend that neither 
the State, EPA, nor the public can verify that reasonable progress will 
be made if the State's assumed pollution reductions to achieve 
reasonable progress are not enforceable.
    Response 4.f: EPA disagrees with the Conservation Groups assertion 
that North Carolina's analysis inappropriately relied on unenforceable 
emission reductions to avoid conducting control analyses for the DEC--
Belews Creek, DEC--Cliffside, DEC--Marshall, DEP--Roxboro, and DEP--
Mayo. North Carolina followed the recommendations in the 2019 Guidance 
to select sources based on 2028 emissions projections.\55\ As explained 
in the NPRM, the State (through VISTAS) developed a 2011 statewide base 
year emissions inventory which was used to project emissions out to 
2028, the end of the second planning period. See 89 FR 67356. The 
accuracy of the 2028 emissions projections for these five Duke Energy 
EGUs is discussed in response 2.c. North Carolina relied on 
sophisticated PSAT modeling to identify visibility impacts of the 
State's AoI sources to any Class I areas, and no Duke Energy EGU met 
the State's PSAT threshold for sulfate or nitrate. Because none of 
these Duke Energy EGUs met the State's source selection criteria, North 
Carolina's decision to not consider whether control measures at these 
sources are necessary for reasonable progress appears reasonable. With 
respect to arguments that the RPGs must be developed based on 
enforceable measures, the RPGs reflect a state's best estimate of 
visibility conditions in the Class I area at the end of planning period 
(e.g., 2028 for the second planning period). Under the RHR, RPGs should 
account for all measures included in a state's LTS, other states' LTSs, 
as well as the implementation of other CAA requirements, including non-
SIP based requirements. The measures underlying the RPGs--except for 
the LTS measures found necessary for reasonable progress--are not 
required to be adopted into the SIP.
---------------------------------------------------------------------------

    \55\ See 2019 Guidance at p. 17 (``Generally, we recommend that 
states use estimates of 2028 emissions (resolved by day and hour, as 
appropriate) to estimate visibility impacts (or related surrogates) 
when selecting sources, rather than values of recent year 
emissions.'').
---------------------------------------------------------------------------

    Regarding the statement that ``[t]he RHR provides that the measures 
necessary to the State's long-term strategy for ensuring reasonable 
progress and its reasonable progress goals must be `as a result of [ ] 
enforceable emissions limitations . . .' '' EPA agrees.\56\ As 
explained in the NPRM (89 FR 67347), 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 determined 
necessary to make reasonable progress toward the national visibility 
goal must be included in a state's LTS and in its SIP. As noted above, 
however, the Duke Energy EGUs did not meet the State's source selection 
criteria, and therefore, North Carolina's decision to not to evaluate 
them for controls appears reasonable.
---------------------------------------------------------------------------

    \56\ ``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).'' See 40 CFR 51.308(f)(2). Measures 
necessary to make reasonable progress must be incorporated into the 
SIP and LTS. The CAA also requires that States incorporate these 
measures into their SIPs. See 42 U.S.C. 7491(b)(2), (b)(2)(B). The 
State may also elect to include additional measures that address 
regional haze, beyond those identified as necessary to make 
reasonable progress, to strengthen the SIP.
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    Regarding the Conservation Groups' references to the 2021 
Clarification Memo regarding in-place and on-the-way measures, these 
references relate to measures necessary for reasonable progress. They 
do not apply to the Duke Energy EGUs because these units did not meet 
the State's source selection criteria, and therefore, they do not have 
measures necessary for reasonable progress. As a result, no measures 
must be adopted into the SIP for these EGUs.
    North Carolina provided a summary in table 7-43 of the 
SO2 and NOX controls, operating status, and 
applicable Federal rules for Duke Energy facilities with coal 
units.\57\ There is no indication in the Haze Plan that the State is 
relying upon these existing measures listed in table 7-43 as existing 
effective controls pursuant to the 2019 Guidance at pages 22-25. In 
fact, North Carolina states on page 254 of its Haze Plan that ``Based 
on current controlled and projected 2028 emissions, the NCDAQ concluded 
that it was not necessary to request that the facilities complete a 
reasonable progress/four-factor analysis to demonstrate progress toward 
achieving the modeled 2028 RPGs discussed in Section 8 of this SIP.''
---------------------------------------------------------------------------

    \57\ See section 7.7.3.2, ``Facilities Not Selected for PSAT 
Modeling,'' of the Haze Plan.
---------------------------------------------------------------------------

    Comment 4.g: The Conservation Groups contend that North Carolina 
arbitrarily and unlawfully refused to conduct FFAs for the Duke Energy 
EGUs despite their undisputed contribution to visibility impairment in 
numerous Class I areas. They provide the following arguments to support 
this contention. First, the text of the CAA and the RHR require the 
State to evaluate the four statutory factors for any source reasonably 
anticipated to cause or contribute to any visibility impairment at any 
Class I area. The Conservation Groups state that North Carolina 
improperly rewrites the statute and regulation to require consideration 
of the four factors only when a source ``significantly contributes'' to 
visibility impairment. Second, the structure of the CAA makes clear the 
requirement to implement emission reductions to ensure reasonable 
progress is not contingent on whether a source significantly 
contributes to visibility impairment. They note that Congress expressly 
uses the modifier ``significant'' in numerous sections of the CAA and 
argue that the modifier is conspicuously absent from CAA section 169A. 
Third, the purpose of the CAA's visibility provisions to reduce and 
ultimately eliminate ``any impairment of visibility'' makes clear that 
Congress ``intended for the term `contributes' as used in 7491(b)(2) to 
encompass smaller

[[Page 92587]]

impacts than would be required to regulate only those sources that 
contribute `significantly.' '' They claim that North Carolina 
``effectively rewrites those provisions of the Act and requires only 
the evaluation of emissions that it deems significant or large 
enough.'' The Conservation Groups acknowledge that there is no bright 
line test for assessing contribution under the RHR, but state that EPA 
has ``made clear that a state's reasonable progress analysis must 
consider a meaningful set of sources and controls that impact 
visibility'' and that if a state fails to do so, EPA must disapprove 
the SIP revision and issue a FIP.
    Response 4.g: EPA agrees that CAA section 169A and the RHR do not 
use the phrases ``significant contribution'' or ``significantly 
contribute'' when discussing the four factors. The CAA and RHR do not 
explicitly list factors that a state must or may not consider when 
selecting the sources for which it will determine what control measures 
are necessary to make reasonable progress.\58\ The appropriate 
threshold for selecting sources may reasonably differ across states and 
Class I areas due to varying circumstances. In setting a threshold, a 
state may consider the number of emissions sources affecting the Class 
I areas at issue, the magnitude of the individual sources' impacts, and 
the amount of anthropogenic visibility impairment at the Class I 
areas.\59\ As discussed in response 2.a, North Carolina considered the 
magnitude of the individual sources' impacts at Class I areas using AoI 
screening and PSAT modeling which appears to be a reasonable approach 
to identifying sources in the State that are reasonably anticipated to 
cause or contribute to visibility impairment in any Class I area.
---------------------------------------------------------------------------

    \58\ See 2019 Guidance at 10.
    \59\ See id. at 19.
---------------------------------------------------------------------------

    Comment 5: The Conservation Groups assert that EPA must disapprove 
North Carolina's SIP revision because the public was not given the 
opportunity to comment on VISTAS modeling and other work products when 
they were being developed. Instead, they contend that North Carolina 
presented the VISTAS work products in its draft SIP as final products 
that are not subject to change, regardless of public input. The 
Conservation Groups also assert that a state must make its regional 
haze SIP and the associated technical work products from the RPOs that 
support the SIP available for public notice and comment. Additionally, 
they contend that when RPOs, like VISTAS, receive funding from EPA to 
develop work products that states rely on when developing their 
regional haze SIPs, EPA must use its grant oversight authority to 
ensure the RPOs' work products comply with all statutory and regulatory 
requirements.
    Response 5: EPA agrees that technical information supporting North 
Carolina's regional haze plan should be available for public review and 
comment but disagrees that the public was not given an opportunity to 
comment on relevant VISTAS work products relied upon by North Carolina 
for the Haze Plan. On August 30, 2021, the State opened the public 
comment period on its proposed Haze Plan through October 15, 2021, and 
on October 6, 2021, it held a public hearing on the Haze Plan. This 
proposed Haze Plan included VISTAS work products (located in appendices 
A-E) that the State relied upon in developing its plan.
    North Carolina exceeded the minimum public notice and comment 
requirements for SIP revisions which are set forth in 40 CFR part 
51.\60\ The CAA does not require states to engage in public notice and 
comment while they are developing modeling and other technical work 
products for use in preparing SIP revisions.
---------------------------------------------------------------------------

    \60\ See 40 CFR 51.102, 51.103, and 40 CFR part 51, appendix V, 
2.1.
---------------------------------------------------------------------------

    Furthermore, the RHR allows states to rely on technical analyses 
developed by RPOs when that analysis is approved by all state 
participants, does not require RPOs to provide notice and comment for 
its work products, and does not require states to provide notice and 
comment during the technical development of their regional haze SIPs. 
See 40 CFR 51.308(f)(2)(iii). The RHR does require states to document 
the technical basis, including modeling, monitoring, cost, engineering, 
and emissions information, on which the State relied to determine the 
emission reduction measures that are necessary to make reasonable 
progress in each Class I area it affects. See id. As discussed above, 
the Haze Plan includes the VISTAS work products relied upon by the 
State.
    EPA also disagrees with the comment that North Carolina 
``communicated in its Haze Plan that the VISTAS products on which the 
State relied for source selection and in setting its reasonable 
progress goals were complete and done'' and presented the VISTAS work 
products as ``final products that would not be changed, regardless of 
any public input.'' The Conservation Groups did not cite to any such 
express language in the Haze Plan. To the extent that North Carolina 
relied on the VISTAS' work products to satisfy regional haze 
requirements, those work products were subject to public notice and 
comment at the state level; EPA evaluated the relevant aspects of the 
VISTAS work products as they relate to the review of the State's Haze 
Plan; they were subject to notice and comment as part of EPA's proposed 
rulemaking, and EPA would not fully approve a SIP revision that it 
determined does not meet regional haze requirements due to flawed work 
products.
    With respect to the comment concerning grant obligations and 
``grant oversight authority,'' EPA has not directly provided any grant 
money to VISTAS for the second planning period. Regardless, EPA 
disagrees with the Conservation Groups' comments regarding the VISTAS 
work products for the reasons discussed in this notice of final 
rulemaking.
    Comment 6: The Conservation Groups assert that EPA shirks its duty 
to review North Carolina's source-specific FFAs. They state that EPA 
proposes to ``rubber stamp'' the SIP submission without engaging in any 
meaningful and independent analysis of North Carolina's FFAs to ensure 
they comply with the CAA and the RHR. Moreover, they assert that 
``[d]espite EPA's stated expectations for this planning period, North 
Carolina does not require any of the sources to adopt additional 
control measures to make reasonable progress'' and that EPA accepts 
North Carolina's decision to ignore ``readily available, feasible, and 
cost-effective controls'' which violates the CAA and RHR. The 
Conservation Groups' specific comments on the FFAs for Domtar, PCS, and 
BRPP are addressed in comments 7 through 9, below.
    Response 6: For various reasons, EPA disagrees with the 
Conservation Groups' contentions. EPA's partial approval and partial 
disapproval of the Haze Plan is a proper exercise of EPA's authority 
under the CAA. Congress crafted the CAA to provide for states to take 
the lead in developing implementation plans, but balanced that decision 
by requiring EPA to review the plans to determine whether a SIP meets 
the requirements of the CAA. When reviewing SIPs, EPA must consider not 
only whether the state considered the appropriate factors in making 
decisions, but also whether it acted reasonably in doing so. In 
undertaking such a review, EPA does not usurp the state's authority but 
ensures that such authority is reasonably exercised.
    Contrary to the comment that the Agency ``shirks'' its CAA 
obligations, EPA has performed its duties with diligence and integrity. 
EPA carefully evaluated the Haze Plan and the

[[Page 92588]]

associated record and engaged in a thorough analysis of each control 
option, including each of the underlying cost assumptions used in the 
calculations. EPA independently evaluated each FFA, including costs, 
and compared each FFA's control determination against EPA's ``Air 
Pollution Control Cost Manual'' (CCM).\61\ After carefully considering 
the submitted comments and the entirety of the record, EPA is now 
shifting from its initial proposal of a partial approval and partial 
conditional approval to a partial approval and partial disapproval. At 
proposal, EPA specifically solicited comment on the adequacy of North 
Carolina's analyses, including the FFAs and determination of controls 
necessary for reasonable progress, and whether the State met the 
requirements of 40 CFR 51.308(f)(2)(i) through (iv). See 89 FR 67358. 
The partial disapproval represents a logical outgrowth of EPA's 
proposal which specifically solicited comments on these determinations 
and conclusions and reflects EPA's receipt and consideration of public 
comments. EPA responds to the Conservation Groups' specific comments on 
the FFAs for Domtar, PCS, and BRPP in responses 7 through 9, below.
---------------------------------------------------------------------------

    \61\ The CCM is available at: https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution.
---------------------------------------------------------------------------

    Comment 7: The Conservation Groups provided several comments on the 
Domtar FFA.\62\ These comments are summarized in comments 7.a through 
7.c below.
---------------------------------------------------------------------------

    \62\ The Conservation Groups erred in reporting the 2020 NEI 
SO2 emissions for Domtar at p. 28 of their comment 
letter. According to the 2020 NEI, the facility emitted 1,054 tons 
for Domtar, not 1,504 tons. The 2020 NEI is located at: https://www.epa.gov/air-emissions-inventories/2020-national-emissions-inventory-nei-data.
---------------------------------------------------------------------------

    Comment 7.a: The Conservation Groups argue that EPA cannot approve 
North Carolina's flawed FFA for Domtar and must require the 
installation of reasonable and cost-effective controls via a FIP. They 
contend that North Carolina ``baldly rejected wet scrubber controls as 
not cost-effective'' at a cost of $3,660/ton SO2 removed for 
the No. 2 Hog Fuel Boiler (HFB2) and that EPA did not provide any 
rationale to support approval of the State's determination. They also 
contend that EPA does not acknowledge multiple errors in North 
Carolina's FFA of wet scrubber controls for HFB2, summarized as 
follows.
    Control Efficiency--The Conservation Groups state that North 
Carolina underestimated the control efficiency that a wet scrubber can 
achieve. They note that modern wet scrubbers can achieve at least 98 
percent control efficiency, the vendor providing the wet scrubber quote 
states that its scrubbers can achieve up to 99 percent control, and the 
FFA does not explain these discrepancies with the 95 percent control 
efficiency assumed by North Carolina.
    Costs--The Conservation Groups assert that North Carolina 
overestimated the cost of a wet scrubber by including unjustified or 
undocumented costs. They allege that the State unreasonably accepted 
the use of an inflated 1.3 retrofit factor, which Domtar attributed to 
``unanticipated delays for installing a wet scrubber.'' However, they 
contend that there is no indication in the FFA that retrofitting HFB2 
with a wet scrubber is unusual and the delays are already considered in 
the contingency fee. The Conservation Groups also argue that the State, 
without adequate explanation or documentation, included sales tax 
although pollution control equipment is tax exempt, increased the 
quoted freight and construction management charges, and included a new 
induced fan at a cost of $3,000,000.
    Cost Effectiveness--The Conservation Groups assert that, after 
correcting for the control analysis errors, the cost effectiveness 
values are $2,968/ton without a new induced fan and $3,244/ton with a 
fan. They contend that these cost-effectiveness values and the $3,660/
ton value are below the cost threshold established by other states, 
claiming that Colorado, Nevada, and New Mexico used a threshold of 
$10,000/ton of pollution reduced. While acknowledging the CAA does not 
require the State to use a bright line rule, they contend that the law 
requires states to explain why it has exercised it discretion in a 
given matter. The Conservation Groups argue that North Carolina must 
establish a threshold, or explain and justify some other objective 
measure, for determining cost-effectiveness that is in line with other 
states' chosen measures and apply that threshold consistently across 
its FFAs. They also note that EPA proposed to disapprove other second 
planning period SIPs where the states ``applied arbitrary cost-
effectiveness threshold or rejected controls that were reasonable and 
cost-effective.''
    Visibility Impact--The Conservation Groups argue that North 
Carolina and EPA disingenuously suggested that the State did not 
utilize visibility impact when rejecting wet scrubber controls for 
Domtar. They contend that North Carolina improperly considered 
visibility as a fifth factor in its decision to reject reasonable and 
cost-effective controls, which they state is contrary to EPA's previous 
assertions and Congress' express exclusion of visibility impact as one 
of the four statutory reasonable progress factors. Therefore, the 
Conservation Groups argue that North Carolina's consideration of 
visibility impacts violates the CAA and the RHR and note that EPA has 
proposed to disapprove second planning period SIPs where states 
improperly relied of the lack of visibility benefit to reject 
reasonable controls.
    Response 7a: EPA agrees in part and disagrees in part with the 
assertion that North Carolina did not provide an adequate rationale to 
support the State's determination that wet scrubber controls at HFB2 
are not cost-effective. As described in more detail below, EPA 
disagrees with certain characterizations by the Conservation Groups 
about the rejected controls and cost analysis. At proposal, EPA 
specifically solicited comment on the adequacy of DAQ's analyses, 
including the FFAs and determination of controls necessary for 
reasonable progress, and whether the State met the requirements of 40 
CFR 51.308(f)(2)(i) through (iv). See 89 FR 67358. After further 
consideration of the analyses, as well as the comments received, EPA 
agrees that overall, North Carolina did not provide an adequate 
rationale to explain why the wet scrubber controls were not cost-
effective, and therefore, not included in the LTS as being necessary 
for reasonable progress. EPA's evaluation of the State's FFA, and 
explanation for why the justification is inadequate, is provided below. 
Due to the inadequate record substantiating the FFA conclusion 
regarding HFB2, together with the concerns discussed in response 7.b 
regarding the lack of enforceable measures in the record for HFB1, EPA 
is disapproving the portions of the Haze Plan addressing 40 CFR 
51.308(f)(2) and (3) and (i)(2) through (4).
    EPA's first basis for disapproval of North Carolina's LTS is the 
inadequate justification that the wet scrubber controls are not cost-
effective for HFB2. There is no requirement in the CAA or the RHR for 
states to establish bright line cost effectiveness thresholds when 
evaluating control costs in FFAs. The CAA and the RHR require states to 
evaluate the costs of compliance, and EPA's 2019 Guidance recommends 
that states follow the recommendations in EPA's CCM to facilitate 
apples-to-apples comparisons of different controls options for the same 
source, and comparisons across different sources.\63\
---------------------------------------------------------------------------

    \63\ See 2019 Guidance at 31.
---------------------------------------------------------------------------

    As described in section 7.8 and appendix I of the Haze Plan, the 
State did not set a specific cost per ton

[[Page 92589]]

threshold for the cost of compliance factor, but rather analyzed each 
facility using the information in EPA's CCM and 2019 Guidance to 
determine whether a given control measure is cost-effective. North 
Carolina determined the cost-effectiveness value for a wet scrubber on 
HFB2 to be $3,660/ton SO2, which is somewhat higher than the 
values calculated by the Conservation Groups ($3,244/ton with a new 
induction fan and $2,968/ton without a new induction fan). As explained 
below, regardless of the range of costs presented by both the State and 
the Conservation Groups, EPA finds that North Carolina did not 
adequately justify why a wet scrubber emissions control in that cost 
range was not necessary for reasonable progress.
    North Carolina states in appendix I that HFB2 is a unique set-up. 
It combusts fuels such as, lignin, natural gas, biomass fuel (including 
paper cores and bleached and unbleached pulp stock), No. 2 fuel oil, 
used oil, sludge, gases collected in the High-Volume Low-Concentration 
(HVLC) system, Low-Volume High-Concentration gases, and stripper off 
gases, and it is used as a control device for several process gas 
streams at the facility. The State reviewed the RACT/BACT/LAER 
Clearinghouse \64\ and did not identify devices similar to HFB2 to 
which the cost effectiveness of a wet scrubber could be compared. 
Therefore, as explained in section 7.8.3.1 of the Haze Plan, it 
requested that EPA adopt the existing measures into the SIP as required 
by CAA section 169A(b)(2) and 40 CFR 51.208(f)(2). Given the lack of 
other hog fuel boilers with similar controls, and the cost of 
compliance and the other statutory factors, North Carolina determined 
the control to not be necessary for reasonable progress.
---------------------------------------------------------------------------

    \64\ EPA's RACT/BACT/LAER Clearinghouse is available at: https://www.epa.gov/catc/ractbactlaer-clearinghouse-rblc-basic-information.
---------------------------------------------------------------------------

    For several reasons, including consideration of the comments 
received after proposal, EPA ultimately does not find North Carolina's 
justification for rejecting the controls compelling. First, although it 
may be accurate that most if not all hog fuel boilers in the country do 
not have wet scrubbers installed, Domtar and the State submitted a 
complete cost analysis and a vendor quote to install a wet scrubber on 
HFB2. It appears that it is possible to install a wet scrubber on the 
particular unit (and achieve at least a 95 percent SO2 
reduction), and neither Domtar nor the State argued otherwise. Unless a 
wet scrubber cannot be installed on HFB2, the lack of a similar 
scrubber in the RACT/BACT/LAER Clearinghouse is not a relevant reason 
for rejecting the control. Second, although EPA has not established a 
bright line cost-effectiveness threshold and all regional haze FFAs and 
SIP decisions will be evaluated on a SIP-by-SIP basis, EPA notes that 
it has found or proposed to find, based on its state-specific 
evaluation of other SIPs, that at least one other state did not 
adequately justify its determination to not adopt controls as part of 
its FFA at cost-effectiveness values higher than the value North 
Carolina considered for Domtar. See, e.g., Air Plan Partial Approval 
and Partial Disapproval; Utah; Regional Haze State Implementation Plan 
for the Second Implementation Period; Air Plan Disapproval; Utah; 
Interstate Transport of Air Pollution for the 2015 8-Hour Ozone 
National Ambient Air Quality Standards; proposed rule, 89 FR 67208 
(August 19, 2024). It is up to each state to adequately justify 
particular cost decisions on a SIP-by-SIP basis, and in this case, EPA 
believes that North Carolina did not provide adequate information in 
the record for rejecting this particular emissions control. Due to this 
inadequate record, it was not reasonable for the State to conclude that 
a wet scrubber at HFB2 is not necessary for reasonable progress.
    EPA acknowledges the Conservation Groups' assertions that the cost 
effectiveness values for HFB2 are below the thresholds used by other 
states during the second planning period, such as Colorado, Nevada, and 
New Mexico which elected to set cost effectiveness thresholds of 
$10,000/ton of pollutant removed. However, North Carolina was not 
required by the CAA or RHR to adopt a similar bright-line cost 
effectiveness threshold when evaluating control costs in FFAs, and the 
relatively high thresholds of up to $10,000/ton set by Colorado, 
Nevada, and New Mexico, do not automatically compel other states to 
follow suit. Each state has discretion to set (or not set) a reasonable 
cost threshold and provide a justification for FFA outcomes.
    While EPA agrees with the Conservation Groups' overall conclusion 
that North Carolina did not adequately justify the cost control 
decisions, EPA does not necessarily agree with all of their specific 
contentions. For example, EPA disagrees with the argument that North 
Carolina underestimated the scrubber control efficiency at HFB2. The 
control efficiency of a wet scrubber is dependent upon a number of 
variables, including the type and design of the wet scrubber system 
used, the absorbing and/or reacting solution or slurry used, packed bed 
height, sump fluid and makeup water balance, scrubber pH, and the 
concentration of SO2 in the inlet waste gas flow.\65\ Domtar 
justified the use of 95 percent control efficiency by citing to a wet 
scrubber estimate from a vendor stating that the scrubber system has 
been designed to achieve a 95 percent collection of SO2 
emissions.\66\ The vendor's estimate for Domtar is tailored based on 
the facility's specifications using Domtar's emission test reports and 
assumptions from similar applications. EPA agrees with the State that 
the 95 percent control efficiency used in the FFA is reasonable given 
the vendor's estimate based on facility-specific information, the 
typical SO2 removal efficiency range for wet scrubbers (90 
to 98 percent),\67\ and the fuel types burned in HFB2.
---------------------------------------------------------------------------

    \65\ See page 1-21, section 5, Chapter 1 of the CCM.
    \66\ The wet scrubber quote from LDX Solutions to Domtar is 
included at pp. 48-53 (pdf numbering) in appendix G-2 of the Haze 
Plan.
    \67\ See table 1.1 on page 1-3, section 5, Chapter 1 of the CCM.
---------------------------------------------------------------------------

    The Conservation Groups included numerous comments on specific 
elements of the cost calculations for the wet scrubber at HFB2. Since 
EPA is partially disapproving the LTS with respect to the emissions 
control decisions at Domtar, it is not necessary to weigh-in on all of 
the specific deficiencies. However, there are some specific issues 
where information provided here may help when re-evaluating the need 
for controls in a potential SIP revision.
    EPA's CCM cannot properly account for all uncertainties, and thus, 
provides that a ``retrofit factor'' can be applied. The CCM states that 
it is typical for the retrofit factor of a wet scrubber to be between 
0.7 and 1.3, depending on the level of difficulty. In any SIP revision, 
a retrofit factor greater than 1.0 should be adequately documented with 
a detailed justification to explain why it is appropriate to inflate 
the costs above those with an average retrofit difficulty.\68\ Based on 
the information provided, EPA is not able to adequately discern whether 
a 1.3 retrofit factor in

[[Page 92590]]

the cost analysis for the wet scrubber for HFB2 is inflated.
---------------------------------------------------------------------------

    \68\ See CCM section 5, Chapter 1, page 1-16: https://www.epa.gov/sites/default/files/2021-05/documents/wet_and_dry_scrubbers_section_5_chapter_1_control_cost_manual_7th_edition.pdf (``An RF of 1 should be used to estimate costs for a 
project of average difficulty. For retrofits that are more 
complicated than average, a retrofit factor of greater than 1 can be 
used to estimate capital costs provided the reasons for using a 
higher retrofit factor are appropriate and fully documented. 
Similarly, new construction and retrofits of existing plants that 
are less complicated should use an RF less than 1. Each project 
should be evaluated to determine the appropriate value for RF.'')
---------------------------------------------------------------------------

    EPA disagrees with the Conservation Groups' statement that the 
costs of the ``unanticipated delays'' are included in the contingency 
costs. Domtar only included the costs of ``unanticipated delays'' in 
the retrofit costs. These retrofit costs address the unexpected 
magnitude of anticipated cost elements; the cost of unexpected delays; 
the cost of re-engineering and re-fabrication; the cost of correcting 
design errors; the cost that reflect additional difficulty associated 
with installing auxiliary equipment; additional insulation and painting 
of piping and ductwork; costs associated with engineering or 
supervision during installation; and unanticipated delays that cause 
production cost. The contingency costs include other unforeseen costs 
such as the cost difference from a change in bank interest rate from 
the historically low 3.25 percent that was used at the time the Haze 
Plan was submitted as well as accounting for the cost difference for 
assuming a higher end of the range equipment life. The contingency 
costs also take into account that any capital investment dollars in 
controls that are deemed reasonable under regional haze would be taking 
investment dollars away from mill projects that would have a return on 
investments. The retrofit costs are completely separate from the 
contingency costs, and therefore, EPA disagrees that any unanticipated 
delay costs in Domtar's FFA are being double counted.
    EPA agrees with the Conservation Groups that a sales tax charge 
should not have been included in the cost analysis for the wet scrubber 
due to North Carolina's Sales and Use Tax Exemption for pollution 
abatement equipment (for air or stream) for manufacturing.\69\ However, 
removing the sales tax from the cost analysis for the wet scrubber 
accounts for approximately one percent of the total direct cost, which 
would not appreciably change the overall cost/ton identified by the 
FFA.
---------------------------------------------------------------------------

    \69\ Information regarding North Carolina's Sales and Use Tax 
Exemption is available at: https://edpnc.com/incentives/pollution-
abatement-and-recycling/
#:~:text=Pollution%20abatement%20equipment%20for%20manufacturing,from
%20sales%20and%20use%20tax.
---------------------------------------------------------------------------

    EPA disagrees with the contention that North Carolina increased the 
quoted amounts for the freight charge and construction management 
without explanation. As explained in appendix I of the Haze Plan, North 
Carolina's approval of Domtar's decision to use the CCM's methodology, 
instead of the vendor quote for the calculation of the freight cost, is 
reasonable because the quote was not detailed and was an estimate that 
did not consider the exact physical specifications and parameters of 
the plant. Furthermore, EPA disagrees that the construction cost was 
double-counted in the overall calculated $/ton based on EPA's review of 
Domtar's FFA calculations because they are using the $344,196 cost, as 
calculated using the methodologies from the CCM, instead of the 
$125,000 vendor quote.
    EPA also disagrees that a $3,000,000 new induced fan was included 
in the FFA without any documentation or explanation. In section 7.8.1.2 
of the Haze Plan, North Carolina notes that an additional fan power 
would be required to overcome the additional pressure drop through the 
wet scrubber. Specifically, in appendix I, North Carolina notes that 
Domtar monitored the existing fan at the facility during startup and 
commissioning of the new electrostatic precipitator (ESP) and found it 
to be sufficient to accommodate the ESP but without excess capacity. 
Therefore, a new induction fan is needed to operate a wet scrubber as 
well as the ESP and Domtar notes that the $3,000,000 was a quote that 
it had received for a new induction fan. EPA notes that North Carolina 
has included appropriate justification for the need for a new induction 
fan in appendix G-2 and appendix I of the Haze Plan and also finds that 
the $3,000,000 cost estimate was developed using reasonable cost 
assumptions and with adequate justification.\70\
---------------------------------------------------------------------------

    \70\ The CCM allows for vendor quotes to be incorporated into 
the cost analysis. See page 1-1, section 5, Chapter 1 of EPA`s CCM.
---------------------------------------------------------------------------

    EPA also disagrees with the Conservation Groups' assertion that 
North Carolina relied on visibility considerations to reject the wet 
scrubber at HFB2. This is clear from statements in the Haze Plan and 
the NPRM. The Haze Plan states that North Carolina ``evaluated the 
SO2 emission reductions and associated improvements in 
visibility at the Swanquarter Wilderness Area associated with the wet 
scrubber control option for the No. 2 Hog Fuel Boiler. This information 
is included solely as supplementary information and is not relied upon 
by the State for its conclusions as noted in Section 7.8.2.2.'' 
Appendix I of the Haze Plan explains in section 3.1.2 that EPA 
requested clarification in section 7.8.1.2 that the visibility benefits 
modeling for the wet scrubber option related to the Domtar HFB2 FFA is 
supplementary information and is not being relied upon by the State for 
its conclusions as noted in section 7.8.2.2. North Carolina responded 
that the ``last paragraph of 7.8.1.2 of the SIP was revised to explain 
that the information is included solely as supplementary information 
and that North Carolina did not rely upon the information to support 
its conclusions documented in section 7.8.2.2 of the SIP. This 
clarification was also added to section 7.8.1.1 of the SIP for BRPP and 
section 7.8.1.3 of the SIP for PCS Phosphate.'' Furthermore, the NPRM 
states that North Carolina did not rely on the supplemental visibility 
information for the Domtar FFA analysis and conclusions and limits its 
evaluation to the four factors. See 89 FR 67355 n.69, 67359-61.
    Comment 7.b: According to the Conservation Groups, EPA must require 
North Carolina's SIP to include enforceable fuel restrictions for the 
No. 1 Hog Fuel Boiler (HFB1). They state that EPA proposed to approve 
North Carolina's exclusion of HFB1 from a FFA because it is equipped to 
only burn natural gas and biomass with No. 2 fuel oil, which is 
projected to emit 12 tpy of SO2 in 2028 (representing one 
percent of Domtar's total SO2 emissions). However, they 
contend that EPA and North Carolina ignore that Domtar's permit 
authorizes HFB1 to burn HVLC gases and No. 2 fuel oil. While 
acknowledging the facility's assertion that it intends to keep the HVLC 
supply line disconnected indefinitely, the Conservation Groups state 
that there are no provisions in the SIP preventing the facility from 
reconnecting the supply line and burning high sulfur content fuel or 
requiring the facility to operate the unit ``infrequently.'' Citing 
EPA's 2019 Guidance, they state that if a SIP lacks the necessary 
provisions to make reasonable progress, the state is required to adopt 
emissions limits as part of its LTS for incorporation into the 
regulatory portion of the SIP. Therefore, they assert that EPA, in a 
FIP, must make the fuel use restrictions enforceable or perform an FFA 
based on any fuels that HFB1 could burn in the future.
    Response 7.b: Concerns regarding the lack of enforceable fuel 
restrictions for Domtar's HFB1 form the second basis for disapproval of 
North Carolina's LTS. North Carolina exempted HFB1 from FFA review 
based on the revised 2028 SO2 emissions projection of 12 tpy 
SO2 (comprising 1.2 percent of Domtar's total 2028 projected 
SO2 emissions) and evaluated HFB2 via a FFA based on 2028 
projected emissions of 1,010 tpy SO2 (comprising 98.8 
percent of Domtar's total 2028 projected SO2

[[Page 92591]]

emissions).\71\ HFB1 did not operate in 2020, 2021, and 2022, and as 
the Conservation Groups note, the HVLC supply line is disconnected 
indefinitely.\72\ EPA acknowledges that performing a control analysis 
on an emissions unit with very low annual emissions, such as 12 tpy, 
would not likely yield any cost-effective controls because the low 
amount of SO2 removed would result in a higher cost per ton 
calculated for each control evaluated. However, the information 
submitted in the Haze Plan documents higher SO2 emissions 
from HFB1 in 2015, 2016, 2017, 2018, and 2019, and notes that there are 
no state or federally enforceable fuel restrictions on HFB1.\73\ Based 
on the comments received and the information in the submitted SIP, EPA 
is concerned that the SIP submission does not include enforceable fuel 
restrictions for HFB1 at Domtar. See Comm. for a Better Arvin v. EPA, 
786 F.3d 1169, 1175-77 (9th Cir. 2015). This concern regarding the lack 
of enforceable measures in the record for HFB1, together with the 
inadequate record substantiating the FFA conclusion regarding HFB2, 
collectively form the basis for EPA's disapproval of the portions of 
the Haze Plan addressing 40 CFR 51.308(f)(2) and (3) and (i)(2) through 
(4).
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    \71\ See ``Projected 2028 Emissions, Revised (tons)'' in table 
7-55 of the Haze Plan for the 2028 projected SO2 
emissions used in the percent calculations. As discussed in 
responses 2 and 4.f, the State's use of 2028 projected emissions 
appears reasonable.
    \72\ See EPA's Emissions Inventory System (EIS) Gateway 
available at: https://www.epa.gov/air-emissions-inventories/emissions-inventory-system-eis-gateway. The 2023 annual emissions 
data for HFB1 will not be available until 2025.
    \73\ See Haze Plan at p. 276. See table 7-56 of the Haze Plan at 
p. 277 for HFB1 SO2 emissions from 2015 through 2020 and 
appendix G-2 at p.12/280 pdf for HFB1 SO2 emissions from 
2016-2018 and p.71/280 pdf for HFB1 SO2 emissions from 
2018-2020.
---------------------------------------------------------------------------

    Comment 7.c: The Conservation Groups assert that EPA's proposal to 
endorse North Carolina's decision to not conduct analyses of 
NOX controls for Domtar was arbitrary and capricious, 
identify three boilers (No. 5 Recovery Boiler, HFB1, and HFB2) as 
significant sources of NOX emissions, and state that North 
Carolina failed to respond to its state-level comments related to 
NOX control at the facility. Therefore, they contend that 
EPA must assess NOX controls at the No. 5 Recovery Boiler, 
HFB1, and HFB2 and require the facility to install reasonable and cost-
effective controls.
    Response 7.c: For the reasons provided in response 3, EPA disagrees 
that the Agency's proposal to not require NOX FFA control 
evaluations of Domtar is arbitrary and capricious. As discussed therein 
and in the NPRM, North Carolina's decision to focus on SO2 
controls in this planning period appears reasonable given, among other 
things, IMPROVE monitoring data from the 2015-2019 five-year period 
showing that ammonium sulfate is the dominant visibility impairing 
pollutant contributing to regional haze at the Class I areas in the 
State.
    EPA also disagrees that North Carolina failed to respond to the 
comments regarding a NOX control evaluation of Domtar. The 
State provided responses to public comments regarding the August 30, 
2021, proposed Haze Plan in appendix I of the final plan. North 
Carolina's responses to public comments on nitrate and NOX 
are included in section 3.4.3 (``Exclusion of NOX/Nitrate/
PM'') of appendix I, pages 37-38, where the State explains why it did 
not evaluate NOX controls during this planning period.\74\
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    \74\ In section 10.4.1 ``Exclusion of NOX from Four-
Factor Analysis'' of the Haze Plan, North Carolina responded to FLM 
comments on this subject.
---------------------------------------------------------------------------

    Comment 8: The Conservation Groups note that North Carolina relied 
on PCS' current title V permit limits for reasonable progress, which 
limits SO2 emissions from Sulfur Acid Plants (SAPs) 5, 6, 
and 7 to 2.5, 2.5, and 1.75 pounds (lbs) per ton of sulfuric acid 
produced, respectively, on a 365-day rolling average. They also note 
that facility upgrades have lowered actual SO2 emissions 
from SAPs 5, 6 and 7 to 1.1, 1.2, and 1.2 lbs per ton of sulfuric acid 
produced.
    The Conservation Groups contend that the State did not analyze 
lowering the SO2 emission limits or imposing work practice 
standards that are reflective of the actual emissions due to the plant 
upgrades; quote the statement in EPA's 2021 Clarification Memo that 
``[a] limit that is significantly higher than the emission rate a 
source is actually achieving does not keep the source from increasing 
its rate in the future;'' and contend that if a control can achieve 
lower emissions rate, the State must assess it as part of an FFA. They 
disagree with North Carolina's interpretation that the quoted statement 
is only applicable to situations where current measures are not 
necessary to make reasonable progress, noting that the quote is located 
in a section of the 2021 Clarification Memo titled ``Determining When 
Existing Measures are Necessary for Reasonable Progress.'' The 
Conservation Groups also state that North Carolina relied on the 
upgrades and actual emissions rates in determining that no additional 
controls are available for the purpose of addressing the existing 
visibility impairment attributable to anthropogenic sources at 
Swanquarter. They argue that the plant upgrades resulting in the actual 
lower emissions rates are existing measures and that the actual 
emission rates must form the basis for the lower emission limits for 
the plant, disagreeing with North Carolina's statement that there is no 
need to impose lower arbitrary limits and no basis on which a lower 
limit could be set that guarantees compliance. The Conservation Groups 
contend that EPA must disapprove North Carolina's control 
determinations for PCS because the State did not consider reasonable 
and highly cost-effective controls for the facility, and that the 
Agency must prepare a FIP that analyzes and requires lower emission 
limits that are reflective of actual emissions.
    Response 8: EPA acknowledges the comments related to the PCS FFA. 
However, because EPA is partially disapproving the portions of the Haze 
Plan addressing 40 CFR 51.308(f)(2), it is not necessary to address the 
Conservation Groups' concerns regarding the PCS FFA at this time. At 
proposal, EPA solicited comments on, among other things, ``the adequacy 
of the permit conditions, including associated monitoring, 
recordkeeping, and reporting, and whether the State has met the 
requirements of 40 CFR 51.308(f)(2)(i) through (iv).'' \75\ The 
decision to disapprove the portions of the Haze Plan addressing 40 CFR 
51.308(f)(2) is a logical outgrowth of the proposal; EPA has given 
further consideration to the question of the adequacy of these 
provisions, the comments received, and the totality of the analyses 
that constitute the LTS and RPGs. As discussed above, EPA will be 
obligated under CAA section 110(c)(1) to promulgate a FIP within two 
years after the effective date of this partial disapproval, unless the 
state submits, and the EPA approves, a SIP revision that satisfies the 
requirements of 40 CFR 51.308(f)(2) and (3) and (i)(2) through (4) 
before EPA promulgates the FIP. The public will have the opportunity to 
comment on, among other things, whether the proposed FIP or the 
proposed SIP action satisfies the FFA requirements of 40 CFR 
51.308(f)(2).
---------------------------------------------------------------------------

    \75\ See 89 FR 67358.
---------------------------------------------------------------------------

    Comment 9: The Conservation Groups contend that the State's and 
EPA's analyses of BRPP are no longer relevant since, according to EPA's 
Enforcement and Compliance History Online database, the facility is 
permanently

[[Page 92592]]

closed as of June 2023. Therefore, they assert that EPA's final SIP 
action must include coordinating and acting in accordance with the 
Comprehensive Environmental, Response, Compensation, and Liability Act 
(CERCLA) Superfund efforts for the site, along with ensuring all 
existing air permits for the facility are revoked.
    Response 9: EPA agrees that North Carolina's FFA analysis and the 
Agency's evaluation of BRPP in the NPRM are no longer relevant. On 
September 18, 2024, BRPP requested the termination of its title V 
permit for the BRPP Canton Mill, Air Quality Permit No. 08961T32, with 
Facility ID 4400159, effective immediately.\76\ This letter states that 
none of the sources in the BRPP title V permit have been operating 
since June 2023. On September 23, 2024, DAQ sent a letter rescinding 
the permit effective on the date of the letter.\77\ Regarding CERCLA, 
the CAA does not require regional haze SIPs to provide for coordination 
and consistency with Superfund efforts.
---------------------------------------------------------------------------

    \76\ The September 18, 2024, letter requesting permit 
termination is in the docket for this rulemaking.
    \77\ The September 24, 2024, permit recission letter is in the 
docket for this rulemaking.
---------------------------------------------------------------------------

    Comment 10: The Conservation Groups assert that EPA cannot approve 
North Carolina's SIP revision because it does not include practically 
enforceable emissions limitations and because this deficiency is not 
cured in the Commitment Letter supporting the conditional approval. 
They also assert that EPA must disapprove the SIP revision because the 
Commitment Letter does not identify specific enforceable measures as 
required under CAA section 110(k)(4) and only contains mere promises to 
adopt unspecified and sometimes unenforceable monitoring, 
recordkeeping, and reporting measures to correct the deficiencies in 
the SIP revision and because EPA ignores additional practical 
enforceability issues in the permit provisions identified for 
incorporation into the SIP.
    Response 10: It is unnecessary to respond to the Conservation 
Groups' comments regarding the sufficiency of the Commitment Letter or 
the practicable enforceability of the permit terms identified for 
incorporation into the SIP because EPA is shifting from its initial 
proposal of a partial approval and partial conditional approval to a 
partial approval and partial disapproval. This action does not 
incorporate any permit conditions into the SIP because the partial 
disapproval includes the LTS, and the Commitment Letter is now moot. 
EPA's decision to disapprove the portions of the Haze Plan addressing 
40 CFR 51.308(f)(2) is a logical outgrowth of the initial proposal and 
EPA's consideration of the comments received. As discussed above, EPA 
will be obligated under CAA section 110(c)(1) to promulgate a FIP 
within two years after the effective date of this partial disapproval, 
unless the State submits, and EPA approves, a SIP revision that 
satisfies the requirements of 40 CFR 51.308(f)(2) and (3) and (i)(2) 
through (4) before EPA promulgates the FIP. Any emission limitations 
identified for incorporation into the SIP in such a SIP revision (or 
into a FIP in the case of an eventual FIP) must be legally and 
practicably enforceable, and EPA encourages the State to consider the 
Conservation Groups' comments if the State opts to develop a SIP 
revision.
    Comment 11: The Conservation Groups contend that EPA's proposal to 
conditionally approve North Carolina's RPGs violates the CAA and RHR. 
They assert that North Carolina impermissibly reversed the ``long-
standing'' SIP planning sequence by setting its RPGs before conducting 
FFAs or finalizing its LTS. They argue that since the RPGs are based on 
VISTAS' modeling conducted in 2020, before the State identified the 
controls necessary for reasonable progress based on the four statutory 
factors and proposed its LTS, the RPGs do not meet the RHR requirement 
that they must be based on enforceable SIP measures. They also assert 
that the State and EPA ignored the 2019 Guidance explaining that a 
state must adjust its RPGs if it conducted modeling for RPGs before 
making final LTS determinations. The Conservation Groups maintain that 
EPA ignores that the State's RPGs do not reflect the visibility 
improvements that the LTS controls will achieve, must disapprove the 
RPGs, and must require the State to adjust them to reflect enforceable 
limitations in the SIP.
    Response 11: EPA agrees with disapproving North Carolina's RPGs but 
differs on the reason for disapproval. EPA reiterates that the process 
for establishing RPGs for each Class I area is prescribed in the RHR 
amendments and discussed in related guidance.78 79 80 The 
RHR requires states with Class I areas to establish RPGs that reflect 
the visibility conditions projected to be achieved by the end of the 
second planning period as a result of the ``enforceable emission 
limitations, compliance schedules, and other measures required under 
the long-term strategy.'' See 40 CFR 51.308(f)(3). As previously 
explained, EPA is disapproving the portions of the Haze Plan addressing 
40 CFR 51.308(f)(2). Therefore, because the requirements in 40 
CFR51.308(f)(3) are dependent upon 40 CFR 51.308(f)(2), EPA is 
disapproving the RPGs because they reflect a deficient LTS.
---------------------------------------------------------------------------

    \78\ See 40 CFR 51.308; 64 FR 35714 (July 1, 1999); and 82 FR 
3078 (January 10, 2017).
    \79\ See 2019 Guidance at pp. 46-48.
    \80\ See 2021 Clarifications Memo at p. 6.
---------------------------------------------------------------------------

    The sequencing of the development of the RPGs is inconsequential 
here because EPA has determined that the State's LTS is deficient. 
Therefore, because the Haze Plan does not include an approvable LTS, 
and compliance with 40 CFR 51.308(f)(3) is dependent on compliance with 
40 CFR 51.308(f)(2), EPA is disapproving the RPGs, and the State should 
re-evaluate them as part of its potential SIP revision.
    Comment 12: The Conservation Groups assert that EPA's proposal to 
approve North Carolina's interstate consultations is arbitrary and 
capricious, and violates the CAA and RHR. They contend that EPA did not 
conduct an independent analysis of the State's consultation process to 
determine whether it satisfies the regulatory requirements. 
Additionally, they argue that State's consultations were ``incomplete, 
inadequately documented, and failed to provide for coordinated 
emissions management strategies with other states.''
    The Conservation Groups maintain that the VISTAS modeling was 
flawed and the source selection process was unreasonable, both of which 
were relied on by North Carolina to identify sources from other states 
that contribute to visibility impairment in its five Class I areas. 
They cite NPCA's analysis using the 2020 NEI and the 2023 Clean Air 
Markets Program Data (CAMPD) to show that there are 169 sources with Q/
d greater than or equal to five, spanning 19 different states, that 
likely contribute to visibility impairment at North Carolina's Class I 
areas. They note that North Carolina did not request consultation with 
some of the states or regarding some sources that were identified by 
the NPCA, including consulting with Kentucky on Ghent Station that they 
contend is likely contributing to visibility impairment at Great Smoky 
Mountains with a Q/d of 40.36, and Louisiana, which has nine sources 
that they contend likely contribute to visibility impairment in North 
Carolina's Class I areas.
    Regarding the adequacy of documentation of consultations, the 
Conservation Groups point to North Carolina's statement in its SIP 
revision that appendix F-1 contains the consultation letters from North 
Carolina to each VISTAS state, along with the

[[Page 92593]]

responses. However, the Conservation Groups found that appendix F-1 
only contains North Carolina's letters. Instead of providing the 
responses it received (only from Tennessee and West Virginia), the 
State provides only summaries of the responses. Furthermore, while 
North Carolina requested consultations with Kentucky, Georgia, and 
Virginia, the responses were not documented, including whether those 
states shared their FFAs for the identified sources, whether there were 
agreements or disagreements between the parties, or whether 
disagreements were reconciled.
    Next, the Conservation Groups assert that North Carolina 
``effectively conducted an `agree to do nothing' consultation 
process,'' which violates the CAA and RHR requirement to engage in 
substantive consultation to develop coordinated strategies that reduce 
emissions with other states in order to make reasonable progress during 
the second planning period. They note that only one (Eastman Chemical 
Company in Tennessee) out of the 16 sources that the State requested 
consultation was required to install new emission controls. The 
Conservation Groups argue that North Carolina acquiesced to other 
states' determinations for their respective sources. For example, they 
state that based on the VISTAS modeling and source selection process 
North Carolina relied on, the General James M. Gavin Power Plant (Gavin 
Plant) in Ohio is the biggest contributor to visibility impairment in 
Great Smoky Mountains, Joyce Kilmer, and Shining Rock, the second 
biggest contributor at Linville Gorge, and the fourth biggest 
contributor at Swanquarter. Nonetheless, they state that North Carolina 
decided it was satisfied with Ohio's determination that the Gavin Plant 
would not be required to install new emission controls.
    Response 12: In response to the Conservation Groups' comments that 
the VISTAS modeling was flawed, North Carolina's source selection 
process was unreasonable, and the State should have requested 
consultation based on NPCA's Q/d analysis, see responses 1 and 2.
    EPA disagrees with the contention that EPA's review of North 
Carolina's interstate consultation process was a box checking exercise. 
EPA independently reviewed all of the consultation documentation 
provided by North Carolina within its Haze Plan. EPA also disagrees 
with the comment that North Carolina conducted a ``do-nothing'' 
approach to consultation, which violates CAA and RHR requirements to 
engage in substantive consultation to develop ``coordinated emission 
reduction strategies'' with other states. 40 CFR 51.308(f)(2) requires 
a state to consult with those states that have emissions that are 
reasonably anticipated to contribute to visibility impairment in the 
mandatory Class I area. The State appears to have reasonably complied 
with 40 CFR 51.308(f)(2)(ii) by consulting with 10 other states and 
requesting FFAs for 16 facilities located within those states with 
visibility impacts to North Carolina's Class I areas exceeding the 
State's sulfate PSAT threshold at one or more of North Carolina's Class 
I areas.\81\ Further, EPA disagrees with the Conservation Groups' 
assertion that North Carolina acquiesced to other states' 
determinations for their respective sources. For example, North 
Carolina assessed and agreed with Ohio's response on the Gavin Plant, 
and therefore, no further action is required under the RHR's 
consultation provisions.\82\ 40 CFR 51.308(f)(2)(ii) does not require 
further action when a state agrees with another state's determination 
that no emission reductions are necessary to make reasonable progress.
---------------------------------------------------------------------------

    \81\ The 16 sources are: Entergy Arkansas Inc-Independence Plant 
in Arkansas; Plant Bowen in Georgia; Gibson and Indiana Michigan 
Power DBA AEP Rockport in Indiana; Tennessee Valley Authority (TVA)-
Shawnee in Kentucky; New Madrid Power Plant-Marston in Missouri; 
Cardinal Power Plant-Cardinal Operating Company (Cardinal Power 
Plant); Duke Energy Ohio--Wm. H. Zimmer Station (Duke-Zimmer); and 
General James M. Gavin Power Plant (Gavin Power Plant) in Ohio; 
Homer City Gen LP/Center and Genon NE Mgmt Co/Keystone Station in 
Pennsylvania; Eastman and TVA-Cumberland in Tennessee; Jewell Coke 
Company LLP in Virginia; and Allegheny-Harrison and Monongahela-
Pleasants Power Station in West Virginia. North Carolina requested 
FFAs of non-VISTAS sources through VISTAS.
    \82\ Appendix F-3d of the Haze Plan includes the June 22, 2020, 
letter from North Carolina, through VISTAS, requesting a FFA of the 
Gavin Plan and a October 29, 2020, letter of response from Ohio. The 
2020 Ohio letter states that the Gavin Plant operates two coal-fired 
boilers (B003 and B004) which have FGDs that operate year-round with 
a 95 percent control efficiency. Ohio requested an SO2 
FFA from the Gavin Plant, and Ohio stated in its letter that the 
plant was considered effectively controlled for NOX with 
a SCR system with 90 percent control efficiency.
---------------------------------------------------------------------------

    Moreover, EPA disagrees with the Conservation Groups' contention 
that North Carolina did not adequately document its consultation 
process within its Haze Plan. Although the RHR requires a state to 
demonstrate that it has included in its implementation plan all 
measures agreed to during interstate consultations or a regional 
planning process, or measures that will provide equivalent visibility 
improvement, and to describe any actions taken in the event states 
disagree with one another on the emission reduction measures necessary 
to achieve reasonable progress in Class I areas, the RHR does not 
prescribe a specific type of documentation to demonstrate that the 
interstate consultation requirements of 40 CFR 51.308(f)(2)(ii) have 
been met. North Carolina documented its correspondence in appendix F-1 
with the states listed in table 10-2 and summarized responses from 
those states in section 10.1.1 of the Haze Plan. Therefore, it appears 
that the State reasonably satisfied the RHR's documentation 
requirements. However, the interstate consultation requirement at 40 
CFR 51.308(f)(2)(ii) is a part of 40 CFR 51.308(f)(2), which is subject 
to the partial disapproval. To the extent that the Domtar facility 
contributes to visibility impairment at out-of-state Class I areas, EPA 
recognizes that the State (or EPA in the case of an eventual FIP), may 
need to reconsider the interstate consultation element under 40 CFR 
51.308(f)(2)(ii). To the extent that the Conservation Groups have 
concerns about facilities outside of North Carolina, including the 
Gavin Plant in Ohio and Ghent Station in Kentucky, any public comments 
related to out-of-state sources should be provided during the public 
comment periods regarding those states' haze plans. North Carolina 
lacks authority to regulate these out-of-state sources, and therefore, 
EPA cannot require other states to implement control measures through 
action on North Carolina's Haze Plan.
    Comment 13: The Conservation Groups maintain that EPA blindly 
proposes to approve the State's consultation with the FLMs by not 
conducting an independent review or analysis. They note that North 
Carolina provided the FLMs an opportunity to consult on the draft SIP 
revision, but argue that the State failed to engage in meaningful 
consultation with the FLMs and largely ignored and failed to adequately 
respond to the FLMs' comments. For these reasons, they argue EPA's 
proposal to approve the State's FLM consultation process is arbitrary 
and capricious and violates the CAA and RHR.
    The Conservation Groups argue that North Carolina treated the FLM 
consultation process as a ``box checking exercise'' by providing terse 
and inadequate responses to FLMs' recommendations. The Conservation 
Groups contend that North Carolina did not incorporate FLM suggestions 
that North Carolina should conduct FFAs of NOX controls for 
the State's major sources due to inaccurate modeling results; the 
source screening process used ``unreasonably high thresholds;''

[[Page 92594]]

lower thresholds \83\ would have led to identification of additional 
facilities; and the State should conduct FFAs of NOX 
controls for the Duke Energy EGUs.
---------------------------------------------------------------------------

    \83\ The Conservation Groups say ``higher thresholds'' on page 
46 of their comments, but EPA believes that this is an error because 
the context of the statement indicates that they intended to say 
``lower thresholds.''
---------------------------------------------------------------------------

    The Conservation Groups contend that since North Carolina's source 
selection, source-specific analyses, LTS, and RPGs violate the CAA and 
RHR, the State's FLM consultations were based on a SIP revision that 
did not meet the statutory and regulatory requirements. They argue that 
EPA must issue a FIP that corrects the errors in the SIP revision and 
consult with the FLMs anew, meaningfully considering, incorporating, 
and responding to FLM recommendations.
    Response 13: The FLMs play important roles in addressing visibility 
at Class I areas, and 40 CFR 51.308(i)(3) requires states to include a 
description of how they address any comments provided by the FLMs 
during the opportunity for consultation. However, neither the CAA nor 
the RHR require a state to agree with the FLM recommendations, nor do 
they specify the degree of consideration that must be given to those 
comments. Rather, 40 CFR 51.308(i)(3) requires a state to ``include a 
description of how it addressed any comments provided by the Federal 
Land Managers'' within its haze plan.
    North Carolina appears to have reasonably complied with this 
requirement by documenting how it addressed the FLMs' comments 
contained in appendix H and appendix I in both section 10.4 of the Haze 
Plan and in section 3.2 of appendix I of its Haze Plan.\84\ For 
example, North Carolina provides an in-depth rationale (approximately 
15 pages) for why it disagrees with NPS' comment recommending inclusion 
of NOX in the FFAs in section 10.4.1 of the Haze Plan.\85\ 
Further, FLM consultation must take place at least 60 days prior to the 
state public comment period on any haze plan or plan revision pursuant 
to 40 CFR 51.308(i)(2). North Carolina initiated consultation with the 
FLMs on April 5, 2021, which was 147 days before the opening of the 
State's public comment period on August 30, 2021. In addition, North 
Carolina met with NPS upon request on May 14 and May 25, 2021, to 
discuss NPS' feedback in more detail.\86\
---------------------------------------------------------------------------

    \84\ Section 3.2 of appendix I addresses NPS comments received 
during the State comment period on the proposed Haze Plan. Section 
10.4 of the Haze Plan addresses FLM comments received prior to the 
State comment period on a draft plan, including section 10.4.2 
related to source selection and section 10.4.3 related to evaluation 
of NOX controls for the Duke Energy EGUs.
    \85\ See section 10.4.1 of the Haze Plan at pp. 320-335.
    \86\ FWS and USFS representatives were also invited to attend 
the May 14 and 25, 2021, North Carolina-NPS consultation meeting. 
See section 10.4 of the Haze Plan.
---------------------------------------------------------------------------

    EPA recognizes that North Carolina appears to have reasonably 
followed all of processes required for FLM consultation consistent with 
40 CFR 51.308(i). However, EPA is disapproving North Carolina's FLM 
consultation under 40 CFR 51.308(i)(2) through (4) because compliance 
with that requirement is dependent on fulfilling the substantive 
requirements of 40 CFR 51.308(f)(2) (LTS). For reasons discussed 
elsewhere in this notice, EPA is disapproving the portions of the Haze 
Plan addressing 40 CFR 51.308(f)(2) and (3). When EPA disapproves an 
LTS, the state (in the case of a SIP revision) or EPA (in the case of a 
FIP) must redevelop an LTS that complies with the statutory and 
regulatory requirements and provide meaningful consultation on the 
substance of the LTS created to replace the substantively disapproved 
one. Even though it appears North Carolina reasonably consulted with 
the FLMs to develop the LTS, because the LTS is disapproved, the 
consultation component must also be disapproved. Therefore, the State 
(for a SIP revision) or EPA (for a FIP) must again consult with the 
FLMs on a revised LTS in order to develop an approvable LTS.
    Regarding the merits of the FLM comments summarized by the 
Conservation Groups and repeated by the NPS in its comments on this 
rulemaking, see responses 17 and 18. Regarding a FIP, as discussed 
above, EPA will be obligated under CAA section 110(c)(1) to promulgate 
a FIP within two years after the effective date of this partial 
disapproval, unless the State submits, and EPA approves, a SIP revision 
that satisfies the requirements of 40 CFR 51.308(f)(2) and (3) and 
(i)(2) through (4) before EPA promulgates the FIP.\87\
---------------------------------------------------------------------------

    \87\ See response 15.
---------------------------------------------------------------------------

    Comment 14: The Conservation Groups assert that EPA should not rely 
on North Carolina's environmental justice (EJ) analysis due to 
deficiencies and that the Agency should conduct an independent 
analysis. The Conservation Groups contend that North Carolina failed to 
respond to their and other commenters' EJ concerns raised during the 
State's public hearing. They also maintain that North Carolina's EJ 
analysis is inadequate because it does not consider the communities 
surrounding the facilities but instead focuses on the communities 
surrounding the Class I areas and that they are not aware of any other 
state that employed this approach. They state that out of the 400-page 
SIP revision (not including appendices), North Carolina's efforts only 
include two pages discussing public participation plans, three pages of 
maps, and less than one page in its response to comments. The 
Conservation Groups assert that the SIP revision is ``entirely void of 
any analysis of how it would benefit North Carolina-identified 
communities of concern for environmental justice.''
    The Conservation Groups argue that EPA's proposal fails to 
recognize the unreasonable approach that the State used to identify the 
geographic areas for consideration in the EJScreen Reports, an approach 
they describe as unique, and that they are not aware of any other state 
that employed this approach. They also assert that EPA's final action 
must provide clarification to the states that impacts local to the 
sources should be considered because North Carolina's analysis failed 
to consider the impacts of SO2 and NOX on 
communities near the emission sources. They argue that North Carolina's 
SIP revision does not contain any analysis on how it would benefit the 
identified communities with EJ concerns, except in the State's 
assertion about the visibility improvement in its Class I areas through 
reductions in SO2 and NOX have reduced impacts on 
the public, including vulnerable communities.
    The Conservation Groups state that the pollutants that contribute 
to visibility impairment in Class I areas can also cause significant 
public health impacts in the area surrounding the source, particularly 
communities of color and low-income communities. They argue that EPA's 
final action should consider and independently analyze the impacts the 
sources have on communities across the State, particularly in 
communities that are disproportionately burdened by environmental 
pollution and explain how a strong regional haze plan will address 
those adverse impacts.
    Based on the Executive Orders (E.O.s) in place since 1994, they 
maintain that EPA is required to incorporate EJ as ``part of its 
mission by identifying and addressing . . . disproportionately high and 
adverse human health or environmental effects of its program, policies, 
and activities,'' which they argue to be applicable to regional haze 
SIP actions' impacts on minority populations and low-income

[[Page 92595]]

populations. Additionally, they argue the directive to incorporate EJ 
into all of the Agency's actions was reaffirmed by the Biden 
Administration through back-to-back E.O.s directed to Federal agencies, 
including EPA, and again in 2023 when the Administration issued the 
``Executive Order on Revitalizing Our Nation's Commitment to 
Environmental Justice for All.'' \88\
---------------------------------------------------------------------------

    \88\ The ``Executive Order on Revitalizing Our Nation's 
Commitment to Environmental Justice for All'' is available at: 
https://www.whitehouse.gov/briefing-room/presidential-actions/2023/04/21/executive-order-on-revitalizing-our-nations-commitment-to-environmental-justice-for-all/.
---------------------------------------------------------------------------

    The Conservation Groups maintain that EPA has the resources, 
including EJScreen, to provide a robust analysis of the EJ impacts of 
North Carolina's SIP revision. Using the EJScreen toolkit, their 
analysis shows five facilities (DEC--Belews Creek; DEC--Cliffside, 
DEC--Marshall, Domtar, and PCS) are surrounded by communities that have 
EJ indicators in the high percentiles.
    Response 14: EPA disagrees with this comment but acknowledges the 
EJScreen information provided by the Conservation Groups. The regional 
haze statutory provisions do not explicitly address considerations of 
EJ and neither do the regional haze regulatory requirements of the 
second planning period in 40 CFR 51.308(f), (g), and (i). However, the 
lack of explicit direction does not preclude the State from addressing 
EJ in its SIP submission. As explained in ``EPA Legal Tools to Advance 
Environmental Justice,'' \89\ the CAA provides states with the 
discretion to consider EJ in developing rules and measures related to 
regional haze. While a state may consider EJ under the reasonable 
progress factors, neither the statute nor the regulation requires 
states to conduct an EJ analysis for EPA to approve a SIP submission. 
The 2021 Clarifications Memo states in section 5.6: ``EPA encourages 
states to consider whether there may be equity and environmental 
justice impacts when developing their regional haze strategies for the 
second planning period. . . . States have discretion to consider 
environmental justice in determining the measures that are necessary to 
make reasonable progress and formulating their long-term strategies, as 
long as such consideration is reasonable and not contrary to the 
regional haze requirements.''
---------------------------------------------------------------------------

    \89\ See ``EPA Legal Tools to Advance Environmental Justice'', 
May 2022, available at: https://www.epa.gov/system/files/documents/2022-05/EJ%20Legal%20Tools%20May%202022%20FINAL.pdf at pp. 35-36.
---------------------------------------------------------------------------

    In this instance, North Carolina elected to consider EJ under the 
reasonable progress factors in section 10.6 and appendix F-5 of the 
Haze Plan. The State ran EJScreen for four of its five Class I areas 
(excluding the Great Smoky Mountains due to its size), and based on the 
results of the EJScreen, it outlined a five-step outreach plan in 
section 10.6 to ensure the opportunity for meaningful community 
involvement during the state-level comment period for the Haze Plan. In 
appendix I of the Haze Plan, in response to an EJ comment received 
during the public comment period, the State notes that EPA's 2021 
Clarifications Memo encourages states to consider EJ and encourages 
states to consider whether there may be equity and EJ impacts when 
developing their regional haze strategies for the second planning 
period while noting that states have discretion to consider EJ in 
determining the measures that are necessary to make reasonable progress 
and formulating LTS, as long as such consideration is reasonable and 
not contrary to the regional haze requirements. North Carolina explains 
in its response that at the time of the issuance of the memo, the State 
had mostly completed the proposed plan for public comment which was 
issued on August 30, 2021. The response also states that North 
Carolina's EJ analysis and additional outreach was an adequate response 
given the short amount of time between when EPA issued its July 8, 
2021, guidance and when regional haze SIPs were due to EPA on July 31, 
2021.
    As discussed above, the CAA and RHR neither prohibit nor require an 
evaluation of EJ with a regional haze SIP. EPA has evaluated North 
Carolina's SIP submission against the statutory and regulatory regional 
haze requirements and determined that it satisfies those minimum 
requirements. For these reasons, the State is not required to address 
the Conservation Groups' alleged EJ inadequacies in its SIP revision, 
and EPA is not required to conduct an independent EJ analysis.
    Comment 15: The Conservation Groups assert that EPA must disapprove 
North Carolina's SIP revision and issue a regional haze FIP for the 
State for the reasons discussed in the comments summarized in comments 
1 through 14, above. They also contend that the Agency should issue a 
regional FIP covering the Region 4 states because ``multiple states in 
Region 4 have developed second planning period SIPs that violate'' the 
CAA and RHR, pointing to reliance on ``invalid VISTAS modeling and 
source selection process,'' and must disapprove Georgia's SIP revision. 
The Conservation Groups also contend that EPA must act swiftly to issue 
a FIP because North Carolina's Haze Plan for the second planning is 
years behind schedule.
    Response 15: EPA has responded to the Conservation Groups' 
rationale for disapproval and a FIP in responses 1 through 14. As 
discussed above, the Agency is approving in part and disapproving in 
part North Carolina's Haze Plan. Therefore, EPA will be obligated under 
CAA section 110(c)(1) to promulgate a FIP within two years after the 
effective date of this partial disapproval, unless the State submits, 
and EPA approves, a SIP revision that satisfies the requirements of 40 
CFR 51.308(f)(2) and (3) and (i)(2) through (4) before EPA promulgates 
the FIP. The Conservation Groups' comments regarding a regional FIP are 
beyond the scope of this rulemaking because this rulemaking relates 
solely to North Carolina's Haze Plan and EPA has not proposed action on 
all of the regional haze SIPs submitted by other states in Region 4. 
Regarding Georgia's regional haze plan, EPA proposed to approve that 
SIP revision in a separate rulemaking on June 3, 2024, and the Agency 
will take final action through that separate rulemaking.\90\
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    \90\ See 89 FR 47481.
---------------------------------------------------------------------------

    Comment 16: NPS states that North Carolina's SIP process missed a 
key CAA section 169A(d) consultation requirement because the State's 
public notice of its regional haze SIP did not include a summary of the 
FLMs' conclusions and recommendations. NPS asserts that this statutory 
requirement ensures public transparency in the SIP development process 
by requiring states to alert the public that the FLMs provide comments 
and to provide a short summary of the recommendations in the notice to 
ease the burden of locating and interpreting these comments in the 
draft SIP revisions. Therefore, NPS recommends that EPA acknowledge and 
address this procedural error when taking final action on North 
Carolina's SIP.
    Response 16: Section 169A(d) of the CAA requires states to include 
a summary of the conclusions and recommendations of the FLMs in the 
notice to the public. This section sets the expectation as to what 
states must share with the public regarding the FLMs' comments. North 
Carolina's August 30, 2021, proposed haze plan subject to public notice 
contained the FLMs' conclusions and recommendations in appendix H, 
which is sufficient because it provides the entirety of the FLMs' 
conclusions and recommendations, rather than a state-generated summary. 
However, because EPA is disapproving the portions of the

[[Page 92596]]

Haze Plan addressing 40 CFR 51.308(f)(2) and (3), North Carolina (for a 
SIP revision) or EPA (for a FIP) must again satisfy the requirements of 
CAA section 169A(d).
    Comment 17: NPS disagrees with EPA's proposal to approve the source 
and pollutant selection portion of the LTS. NPS states that North 
Carolina unreasonably applied the AoI and PSAT results to exclude 
significant sources and pollutants from analysis, that it has raised 
these concerns with the State since May 2021, and that neither North 
Carolina nor EPA substantively addressed these concerns.
    Source Selection Approach--NPS argues that North Carolina's source 
selection thresholds are ``excessively high'' and are ``flawed and 
counterproductive'' to remedying existing visibility impairment. 
According to NPS, the VISTAS source selection approach, relying on a 
percent-of-total-impact threshold for selecting each facility, results 
in an individual facility needing to have a greater impact on 
visibility to be selected for more impaired Class I areas than with 
less impaired ones. NPS states that the AoI percent-of-total-impact 
threshold for selecting a facility is 74 times higher for Mammoth Cave 
National Park (Mammoth Cave) and 19 times higher for Great Smoky 
Mountains when compared to Everglades National Park, the least impacted 
NPS Class I area in the region. NPS argues that this approach resulted 
in the selection of very few sources for FFAs in a region experiencing 
significant visibility impairment and states that no North Carolina 
source was selected for impacts to Great Smoky Mountains or other NPS 
Class I areas. NPS also argues that it is difficult to assess 
reasonable progress if few sources are brought forward for FFAs. NPS 
asserts that neither EPA nor North Carolina substantively addressed 
this issue or described how the source selection thresholds are 
consistent with the need to demonstrate reasonable progress.
    Pollutant Selection Approach--NPS asserts that North Carolina used 
an outdated 2011 modeling platform to draw conclusions about which 
pollutants are responsible for visibility impairment. NPS states that 
recent monitoring data shows that the ammonium nitrate contribution on 
the 20 percent most-impaired days has increased since 2011 and is now a 
significant component of visibility impairment in Mammoth Cave and 
Shenandoah National Park (Shenandoah). While NPS agrees that sulfate is 
the dominant contributor to visibility impairment in those areas, it 
notes that nitrate contributions have more than doubled in recent years 
and are also significant. NPS encourages EPA to consider the 2021 
Clarification Memo's direction on pollutant selection in assessing 
North Carolina's approach and recommends the evaluation of North 
Carolina's sources for opportunities to reduce NOX 
emissions.
    Response 17: See response 1 regarding the 2011 base year and 
response 2 regarding North Carolina's source selection approach. See 
response 3 regarding nitrate contributions at the North Carolina Class 
I areas and pollutant selection. Additionally, there is no evidence 
provided by NPS that Mammoth Cave or Shenandoah are affected by 
emissions from within North Carolina (in particular, NOX 
emissions which may impact nitrate). Therefore, contributions to 
nitrate at those Class I areas are not relevant to North Carolina's 
Haze Plan.
    Comment 18: NPS notes that North Carolina did not conduct FFAs of 
NOX and SO2 emissions at five Duke Energy EGUs 
identified by NPS for such an evaluation, instead concluding that 
SO2 emissions from these EGUs are effectively controlled 
without any substantive analysis.\91\ NPS asserts that EPA's proposed 
determination that FFAs are not necessary for these EGUs and that they 
are effectively controlled for SO2 is flawed and 
inconsistent with EPA guidance because it: (1) does not consider the 
full suite of EPA guidance on effective controls, (2) relied on flawed 
assumptions to estimate SO2 control efficiencies, and (3) 
did not assess NOX emissions. NPS recommends that EPA 
require FFAs for SO2 and NOX at these EGUs which 
should consider whether scrubber upgrades or optimizations are cost 
effective.
---------------------------------------------------------------------------

    \91\ The five Duke Energy EGUs identified by NPS are DEC--Belews 
Creek, DEC--Cliffside, DEC--Marshall, DEP--Roxboro, and DEP--Mayo.
---------------------------------------------------------------------------

    EPA Guidance--NPS maintains that EPA narrowly viewed the Agency's 
guidance in relying heavily on two effective control examples in the 
2019 Guidance--(1) EGUs with add-on flue gas desulfurization (FGD) that 
meet the 0.2 lb/MMBtu MATS SO2 limit for coal-fired EGUs, 
and (2) EGUs that installed FGD during the first implementation period 
that operates year-round with an effectiveness of at least 90 percent. 
NPS states that EPA did not consider additional guidance that ``caveats 
how `off-ramps' to source selection should be used,'' pointing to 
section 2.3 of the 2021 Clarifications Memo. NPS states that, with 
respect to MATS, the guidance recommends that states should also 
consider control equipment past performance in their reasonable 
progress determinations and recommends reasonable actions to ensure 
controls are maintained and operated to achieve optimal performance. 
NPS states that the Duke Energy EGUs have operated at lower emission 
rates in the past and that its evaluation of SO2 and 
NOX emissions information in the CAMPD demonstrates that 
SO2 and NOX emissions generally increased in 
recent years, suggesting that the controls at these facilities may not 
be operating to maintain optimum performance or achievable emission 
rates.
    NPS also argues that FGD installed after 2007 should meet a control 
effectiveness of 95 percent or higher, pointing to a ``caveat'' in the 
2019 Guidance regarding the 90 percent control efficiency ``off-ramp'' 
that EPA cites in its proposal to approve. This ``caveat'' states that 
EPA expects any FGD system installed to meet CAA requirements since 
2007 would have an effectiveness of 95 percent or higher. NPS also 
points to EPA's January 4, 2017, Texas Best Available Retrofit 
Technology (BART) FIP in which it contends that EPA set a 95 percent 
SO2 control benchmark for deciding if a scrubber should be 
evaluated for upgrades or replacement.
    SO2 Control Assumptions--NPS states that EPA's evaluation of 
SO2 removal efficiency at the Duke Energy EGUs relied on 
assumptions that may slightly overestimate scrubber efficiency. NPS 
maintains that the equation used by EPA to estimate uncontrolled 
emissions overestimated these emissions and the resulting control 
efficiencies. NPS recommends using AP-42 emission factors for 
bituminous coal, and other fuels, to estimate the uncontrolled 
emissions. Using the AP-42 factor for bituminous coal, NPS estimates 
that scrubber performance is periodically lower than 95 percent for 
DEC--Cliffside Unit 5, DEC--Belews Creek Units 1 and 2, DEP--Roxboro 
Units 2 and 4A, and DEC--Marshall Units 1 and 2 and is periodically 
lower than 90 percent for units at DEP--Roxboro, DEC--Belews Creek, and 
DEC--Cliffside. NPS recommends reviewing permit limits to ensure that 
optimum scrubber performance is consistently achieved and to prevent 
backsliding.
    NOX Emissions--NPS recommends that EPA and North Carolina evaluate 
the NOX controls at the Duke EGUs. According to the NPS, 
replacing existing SNCR systems with modern SCR systems at DEC--
Marshall (Units 1, 2, and 4) would be cost effective at $4,000-$6,000/
ton and would reduce

[[Page 92597]]

NOX emissions by up to 5,700 tpy. Additionally, NPS found 
that performance of the SCR for Duke Energy's EGUs have deteriorated in 
recent years. NPS recommends analyzing past performance as a potential 
control option for the Duke EGUs with SCR.
    Response 18: EPA Guidance--See response 4 regarding evaluation of 
these Duke Energy sources via a SO2 FFA. Regarding the NPS 
comments that the SO2 and NOX emissions at these 
Duke Energy EGUs have generally increased in recent years, which 
suggests that the controls at these facilities may not be operating to 
maintain optimum performance or achievable emission rates, North 
Carolina did not select DEC--Belews Creek, DEC--Cliffside, DEC--
Marshall, DEP--Mayo, or DEP--Roxboro for an FFA because the visibility 
impacts from these sources were below North Carolina's source selection 
thresholds. Because these sources were not selected for an FFA, North 
Carolina's decision not to evaluate them for controls appears 
reasonable.
    EPA clarifies that North Carolina and EPA are not relying on 
section 2.3 (``Sources that are Not Selected Based on Existing 
Effective Controls'') of the 2021 Clarifications Memo and 2019 Guidance 
(pp. 22-25) for DEC--Belews Creek, DEC--Cliffside, DEC--Marshall, DEP--
Mayo, or DEP--Roxboro. Section 2.3 of the 2021 Memo is applicable to 
sources that met the source selection criteria set by the State under 
the RHR and, instead of a FFA, the State provided a showing that the 
source has existing, effective controls such that a FFA is unlikely to 
result in new additional controls. None of these five Duke Energy EGUs 
met North Carolina's source selection criteria for a FFA (i.e., none 
met or exceeded the PSAT sulfate or nitrate thresholds). However, in 
the NPRM (89 FR 67359), EPA evaluated these Duke Energy EGUs to 
evaluate the reasonableness of North Carolina's source selection 
thresholds.\92\ EPA documented an analysis that further examined the 
Duke Energy sources to verify North Carolina's claim that there were no 
uncontrolled or lightly controlled sources in North Carolina that were 
not selected. Regarding scrubber control efficiencies, in the NPRM (89 
FR 67359), EPA provided data from 2017-2021 indicating that existing 
WFGD systems at the five Duke Energy facilities routinely achieve 92 to 
98 percent SO2 removal efficiencies. In this rulemaking 
action, EPA also considered data from 2022 and found that the Duke 
Energy emissions units have annual average scrubber removal 
efficiencies ranging between 93.8-99.2 percent with all units having a 
six year average (2017-2022) SO2 removal efficiency of 
greater than 95 percent.\93\ Therefore, it appears reasonable to assume 
that an FFA would likely result in the conclusion that no further 
SO2 emissions controls (including WFGD upgrades) are 
necessary. See 89 FR 67359.
---------------------------------------------------------------------------

    \92\ See 2019 Guidance at p. 19 (``For example, it may be 
difficult to show reasonableness of a threshold set so high that an 
uncontrolled or lightly controlled source that is one of the largest 
contributors to anthropogenic light extinction at a Class I area is 
excluded.'').
    \93\ See North Carolina Duke Energy scrubber efficiency data 
file that is included in the docket for this action.
---------------------------------------------------------------------------

    Regarding EPA's potential overestimate of scrubber efficiency, EPA 
agrees that using the AP-42 equation assumption for bituminous coal 
(uncontrolled) combustion would slightly reduce the calculated scrubber 
efficiencies.\94\ However, such a small change in efficiency is 
negligible here. Adjusting EPA's scrubber efficiency calculations would 
change the annual average efficiencies from 93.8-99.2 percent to 93.5-
99.2 percent and the six-year average efficiencies would still all be 
greater than 95 percent.
---------------------------------------------------------------------------

    \94\ AP-42, Compilation of Air Pollutant Emissions Factors from 
Stationary Sources'' is available at: https://www.epa.gov/air-emissions-factors-and-quantification/ap-42-compilation-air-emissions-factors-stationary-sources.
---------------------------------------------------------------------------

    Regarding NPS' statement that FGDs installed after 2007 should meet 
a control effectiveness of 95 percent or higher,\95\ this is a general 
recommendation from EPA's 2019 Guidance that applies to states that are 
providing demonstrations that selected sources already have effective 
emission control technology in place and is not intended to be a 
``bright-line'' recommendation. EPA disagrees that EPA's January 4, 
2017, Texas BART FIP sets a 95 percent SO2 control benchmark 
for deciding if a scrubber should be evaluated for upgrades or 
replacement. First, there is nothing in the RHR that establishes such a 
requirement. Second, the Duke Energy sources were not selected, and 
therefore, no control analysis was required for the second planning 
period. Additionally, the analysis in the first planning period Texas 
BART FIP is not relevant to the current situation for the North 
Carolina second planning period SIP. The Texas FIP examined EGU sources 
following the EPA's first planning period BART Guidelines,\96\ which is 
not relevant here. The BART Guidelines established presumptive scrubber 
efficiencies and emissions rates \97\ that are not a requirement for 
the second planning period. Also, the Texas BART FIP analyzed sources 
that either did not have scrubbers or were operating old inefficient 
scrubbers that only achieved 60-80 percent SO2 efficiency. 
In addition, the Texas coal burning EGU sources also differed in the 
type of coal burned. All of the North Carolina EGUs burn bituminous 
coal, whereas all of the Texas EGUs burn low-sulfur subbituminous coal 
or lignite.
---------------------------------------------------------------------------

    \95\ See id. at p. 24, footnote 53 (``While a 90 percent control 
effectiveness is used in this example, we expect that any FGD system 
installed to meet CAA requirements since 2007 would have an 
effectiveness of 95 percent or higher.'').
    \96\ See 40 CFR part 51, appendix Y--``Guidelines for BART 
Determinations Under the Regional Haze Rule'' (BART Guidelines).
    \97\ See BART Guidelines at section IV.E.4 (``You must require 
750 MW power plants to meet specific control levels for 
SO2 of either 95 percent control or 0.15 lbs/MMBtu, for 
each EGU greater than 200 MW that is currently uncontrolled unless 
you determine that an alternative control level is justified based 
on a careful consideration of the statutory factors.'').
---------------------------------------------------------------------------

    SO2 Control Assumptions--Regarding NPS' recommendations to review 
permit limits to ensure that optimum scrubber performance is 
consistently achieved and to prevent backsliding, as explained earlier, 
because these sources were not selected for an FFA, North Carolina's 
decision not to evaluate them for controls appears reasonable.
    NOX Emissions--With respect to the recommendation that EPA require 
NOX FFAs for these five Duke Energy EGUs, see response 3.
    Comment 19: The Organizations contend that the Haze Plan fails to 
reduce pollution and falls short on the State's obligation to improve 
air quality for protected parks, wilderness areas, and communities. 
Additionally, they state that they are disappointed that EPA has 
proposed to approve this highly flawed and problematic plan.
    Specifically, they contend that the State's plan relied on a flawed 
modeling system prepared by VISTAS. They contend that VISTAS modeling 
used decade-old data, does not accurately represent nor include 
NOX emissions contributing to haze pollution, and does not 
include many of the biggest polluting facilities in the state that are 
exacerbating haze pollution.
    The Organizations also contend that North Carolina used 
unreasonably high source selection thresholds that excluded Duke 
Energy's coal-fired power plants from a full review for control 
analyses or requirements. The Organizations state that these Duke 
facilities are some of the biggest haze polluters in the State.
    The Organizations state that EPA shirked its duty to review North

[[Page 92598]]

Carolina's FFA; deferred to North Carolina's highly deficient EJ 
analysis; and proposed an action that is inconsistent with EPA's 
proposed disapprovals in whole or part of haze plans from other states 
such as Arizona, Missouri, North Dakota, Wyoming, and Utah. They urge 
EPA to issue either a FIP for North Carolina or a FIP for all states in 
Region 4, given that all Region 4 states relied on VISTAS modeling that 
they contend is invalid for source selection.
    Response 19: Regarding the Organizations' assertions related to 
VISTAS modeling, see response 1. Regarding the Organizations' comments 
concerning source selection thresholds, see response 2. Regarding the 
Organizations' arguments related to the North Carolina Duke Energy 
power plants, see response 4. Regarding the Organization's comments 
that EPA neglected its duty to review the FFAs, see response 6. 
Regarding the Organizations' comments about EJ, see response 14. 
Regarding the Organizations' comments about a FIP, see response 15.
    The Organizations' comment regarding rulemaking consistency is 
unclear with respect to the specific alleged inconsistencies between 
this action and the cited proposed actions. Therefore, EPA is unable to 
respond to this comment other than to note that EPA is now shifting 
from its initial proposal of a partial approval and partial conditional 
approval to a partial approval and partial disapproval.
    Comment 20: EPA received one set of relevant comments from a member 
of the public (hereinafter referred to as the ``Commenter''). The 
Commenter states the national parks and forests in the Southern 
Appalachia region experience some of the worst air pollution in the 
country and notes that air pollution poses a threat to human health 
(e.g., heart attacks, heart failure, cancer, and respiratory diseases), 
especially in marginalized communities. The Commenter maintains that 
the RHR requires states to develop a plan to reduce anthropogenic air 
pollution that affects Class I areas, that local economies of 
communities surrounding Class I areas are dependent on tourism to these 
areas and contends that park visitation drops by eight percent when air 
quality is poor.
    The Commenter asserts that the Haze Plan misses opportunities to 
reduce emissions and many industrial pollution sources will remain 
unchecked, and that it will continue to allow up to 53,000 tons of 
haze-causing pollutants (SO2 and NOX) to be 
emitted. The Commenter contends that the State excluded ``the largest 
and dirtiest sources of air pollution,'' coal-burning power plants, 
from its plan and that the State also excluded two harmful air 
pollutants, soot and NOX, from consideration.
    The Commenter refers to EPA's proposed approval as a ``rubber-
stamp'' of North Carolina's ``do-nothing regional haze plan.'' The 
Commenter maintains that North Carolina's plan is ``weak'' because it 
is based on flawed modeling from VISTAS and that EPA ``shirked its 
duty'' to review the State's source-specific FFAs; ``incorrectly'' 
allowed the State to exclude NOX controls in its FFAs; 
supported the State's exclusion of Duke Energy's five coal-burning 
power plants from any control analyses or requirements; and deferred to 
the State's ``highly deficient'' EJ analysis. The Commenter asserts 
that a weak air quality plan in North Carolina will continue to place 
the disproportionate environmental burden on black and low-income 
communities.
    Response 20: Regarding the Commenter's assertions that the modeling 
from VISTAS is flawed, see response 1. With respect to the concern 
regarding the exclusion of NOX and soot \98\ controls, see 
response 3.\99\ Regarding the statement that North Carolina excluded 
``Duke Energy's five coal-burning power plants'' from any control 
analyses or requirements, it is unclear which Duke Energy power plants 
are being referenced, however, should those five power plants be 
referring to DEC--Belews Creek, DEC--Cliffside, DEC--Marshall, DEP--
Mayo, and DEP--Roxboro, see response 4. Regarding the statements that 
EPA ``shirked its duty'' to review the State's source-specific FFAs and 
that North Carolina's plan is a ``do-nothing regional haze plan,'' see 
response 6. With respect to the EJ comments, see response 14. Regarding 
``53,000 tons of haze-causing pollutants (SO2 and 
NOX),'' the Commenter did not identify the source of data 
for this figure, and thus, EPA is unable to respond to this aspect of 
the comment.
---------------------------------------------------------------------------

    \98\ The Commenter did not define the term ``soot.'' EPA assumes 
the Commenter is referring to particulate matter.
    \99\ In table 2, the directly emitted PM species are coarse 
mass, elemental carbon, fine sea salt and fine soils.
---------------------------------------------------------------------------

III. EJ Considerations

    As explained in EPA Legal Tools to Advance Environmental Justice 
and the 2021 Clarifications Memo, CAA section 169A and the RHR provide 
states with the discretion to consider EJ in developing rules and 
measures related to regional haze.\100\ In this instance, DAQ exercised 
this discretion. In reviewing DAQ's analysis, EPA defers to North 
Carolina's reasonable exercise of its discretion in considering EJ in 
this way. The information associated with DAQ's analysis is included in 
the NPRM for informational purposes only; it does not form any part of 
the basis of EPA's action.
---------------------------------------------------------------------------

    \100\ EPA Legal Tools to Advance Environmental Justice (May 
2022) is available at: https://www.epa.gov/system/files/documents/2022-05/EJ%20Legal%20Tools%20May%202022%20FINAL.pdf; 2021 
Clarifications Memo at p. 16.
---------------------------------------------------------------------------

    DAQ describes North Carolina's EJ Program for regional haze in 
section 10.6 of the 2022 Plan which includes outreach plans to provide 
an opportunity for meaningful involvement of all people regardless of 
race, color, national origin, or income during the comment period of 
this regional haze plan for North Carolina. DAQ ran EJScreen,\101\ an 
EJ mapping and screening tool that provided a nationally consistent 
dataset and approach for combining various environmental and 
demographic indicators, around the North Carolina Class I areas except 
for Great Smoky Mountains because the area is too large to perform the 
EJScreen analysis. Based on the EJScreen results, which are included in 
appendix F-5 of the Haze Plan, DAQ implemented its outreach plan, 
including conducting specific outreach during the comment period on the 
August 30, 2021, proposed haze plan to communities within potentially 
underserved block groups that overlap or are within one mile of the 
North Carolina Class I areas. DAQ also provided project information and 
updates to the Eastern Band of the Cherokee Nation. Section IV of the 
technical support document provides a more detailed summary of how 
North Carolina opted to consider EJ in development of the 2022 Plan. 
While EPA commends North Carolina's consideration of EJ when developing 
its SIP revision, the EJ analyses submitted by DAQ were considered but 
were not the basis for EPA's action.
---------------------------------------------------------------------------

    \101\ EPA's EJScreen tool is available at: https://www.epa.gov/ejscreen.
---------------------------------------------------------------------------

IV. Final Action

    EPA is approving in part and disapproving in part North Carolina's 
April 4, 2022, SIP submission addressing the regional haze requirements 
for the second planning period contained in 40 CFR 51.308(f). 
Specifically, EPA is approving the portions of the Haze Plan addressing 
the requirements of 40 CFR 51.308(f)(1), (f)(4) through (6), and (g)(1) 
through (5).

[[Page 92599]]

EPA is disapproving the portions of the Haze Plan addressing the 
requirements of 40 CFR 51.308(f)(2) and (3) and (i)(2) through (4). 
Thus, EPA will be obligated under CAA section 110(c)(1) to promulgate a 
FIP within two years after the effective date of this partial 
disapproval, unless the State submits, and EPA approves, a SIP revision 
that satisfies the requirements of 40 CFR 51.308(f)(2) and (3) and 
(i)(2) through (4) before EPA promulgates the FIP.

V. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the Act and applicable 
Federal regulations. See 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, EPA's role is to review state choices, and 
approve those choices if they meet the minimum criteria of the Act. 
Accordingly, this final action partially approves and partially 
disapproves a SIP submission as meeting or not meeting Federal 
requirements, respectively, and does not impose additional requirements 
beyond those imposed by state law.
    Additional information about these statutes and Executive Orders 
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 14094: Modernizing Regulatory Review

    This action is not a significant regulatory action as defined in 
Executive Order 12866, as amended by Executive Order 14094, and was 
therefore not subject to a requirement for Executive Order 12866 
review.

B. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under 
the PRA because it does not contain any information collection 
activities.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. This 
action will not impose any requirements on small entities because it 
merely partially approves and partially disapproves a SIP submission as 
meeting or not meeting Federal requirements, respectively.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate as described in 
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect 
small governments. The action imposes no enforceable duty on any state, 
local or Tribal governments or the private sector.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states, or on the distribution of power 
and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    This action does not have Tribal implications, as specified in 
Executive Order 13175, because the SIP is not approved to apply on any 
Indian reservation land or in any other area where EPA or an Indian 
Tribe has demonstrated that a Tribe has jurisdiction and will not 
impose substantial direct costs on Tribal governments or preempt Tribal 
law. Thus, Executive Order 13175 does not apply to this action.

G. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that concern environmental health or safety risks 
that EPA has reason to believe may disproportionately affect children, 
per the definition of ``covered regulatory action'' in section 2-202 of 
the Executive Order. Therefore, this action is not subject to Executive 
Order 13045 because it merely partially approves and partially 
disapproves a SIP submission as meeting or not meeting Federal 
requirements, respectively. Furthermore, EPA's Policy on Children's 
Health does not apply to this action.

H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    This action is not subject to Executive Order 13211 because it is 
not a significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act (NTTAA)

    This rulemaking does not involve technical standards.

J. Executive Order 12898 and Executive Order 14096: Federal Actions To 
Address Environmental Justice in Minority Populations and Low-Income 
Populations and Revitalizing Our Nation's Commitment to Environmental 
Justice for All

    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 communities with EJ concerns to the 
greatest extent practicable and permitted by law. Executive Order 14096 
(Revitalizing Our Nation's Commitment to Environmental Justice for All, 
88 FR 25251, April 26, 2023) builds on and supplements E.O. 12898 and 
defines EJ as among other things, the just treatment and meaningful 
involvement of all people regardless of income, race, color, national 
origin, or Tribal affiliation, or disability in agency decision-making 
and other Federal activities that affect human health and the 
environment.
    DAQ evaluated EJ considerations as part of its SIP submittal even 
though the CAA and applicable implementing regulations neither prohibit 
nor require an evaluation. EPA's evaluation of DAQ's EJ considerations 
are described above in the section titled, ``EJ Considerations.'' The 
analysis was done for the purpose of providing additional context and 
information about this rulemaking to the public, not as a basis of the 
action. EPA is finalizing action under the CAA on bases independent of 
North Carolina's evaluation of EJ. 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. In addition, there is 
no information in the record upon which this decision is based that is 
inconsistent with the stated goal of Executive Order 12898/14096 of 
achieving EJ for communities with EJ concerns.

K. Congressional Review Act (CRA)

    This action is subject to the CRA, and EPA will submit a rule 
report to each House of the Congress and to the Comptroller General of 
the United States. This action is not a ``major rule'' as defined by 5 
U.S.C. 804(2).

L. Petitions for Judicial Review

    Under section 307(b)(1) of the CAA, petitions for judicial review 
of this action must be filed in the United States Court of Appeals for 
the appropriate

[[Page 92600]]

circuit by January 21, 2025. Filing a petition for reconsideration by 
the Administrator of this final rule does not affect the finality of 
this rule for the purposes of judicial review nor does it extend the 
time within which a petition for judicial review may be filed and shall 
not postpone the effectiveness of such rule or action. This action may 
not be challenged later in proceedings to enforce its requirements (see 
section 307(b)(2) of the CAA).

List of Subjects in 40 CFR Part 52

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

    Dated: November 14, 2024.
Cesar Zapata,
Acting Regional Administrator, Region 4.

    For the reasons stated in the preamble, EPA amends 40 CFR part 52 
as follows:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

0
1. The authority citation for part 52 continues to read as follows:

    Authority: 42 U.S.C. 7401 et seq.

Subpart II--North Carolina

0
2. In Sec.  52.1770, amend the table in paragraph (e) by adding an 
entry for ``Regional Haze Plan--Second Planning Period'' at the end of 
the table to read as follows:

Sec.  52.1770  Identification of plan.

    (e) * * *

                              EPA-Approved North Carolina Non-Regulatory Provisions
----------------------------------------------------------------------------------------------------------------
                                                                     Federal
          Provision            State effective    EPA approval       Register               Explanation
                                     date             date           citation
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Regional Haze Plan--Second           4/4/2022       11/22/2024   [Insert first    Approval of the portions of
 Planning Period.                                                 page of          the Haze Plan addressing the
                                                                  Federal          requirements of 40 CFR
                                                                  Register         51.308(f)(1), (f)(4)-(6), and
                                                                  citation].       (g)(1)-(5). Disapproval of
                                                                                   the portions of the Haze Plan
                                                                                   addressing the requirements
                                                                                   of 40 CFR 51.308(f)(2),
                                                                                   (f)(3), and (i)(2)-(4).
----------------------------------------------------------------------------------------------------------------

0
3. Section 52.1776 is added to read as follows:

Sec.  52.1776  Visibility protection.

    (a) Disapproval. On April 4, 2022, the North Carolina Department of 
Environmental Quality, Division of Air Quality submitted a revision to 
its SIP to address regional haze for the second planning period. The 
portions of this SIP revision addressing the requirements of 40 CFR 
51.308(f)(2) and (3) and (i)(2) through (4) are disapproved.
    (b) [Reserved]

[FR Doc. 2024-26980 Filed 11-21-24; 8:45 am]
BILLING CODE 6560-50-P
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