[Federal Register Volume 87, Number 192 (Wednesday, October 5, 2022)]
[Rules and Regulations]
[Pages 60273-60292]
[FR Doc No: 2022-21249]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R06-OAR-2017-0558; FRL-9308-02-R6]

Finding of Failure To Attain the Primary 2010 One-Hour Sulfur
Dioxide Standard for the St. Bernard Parish, Louisiana Nonattainment
Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is making a
determination that the St. Bernard Parish sulfur dioxide
(SO2) nonattainment area (``St. Bernard area'' or ``area'')
failed to attain the primary 2010 one-hour SO2 national
ambient air quality standard (NAAQS) under the Clean Air Act (CAA or
the Act) by the applicable attainment date of October 4, 2018. This
determination is based upon consideration of and review of all relevant
and available information for the St. Bernard area leading up to the
area's attainment date of October 4, 2018, including emissions and
monitoring data, compliance records for the area's primary
SO2 source, the Rain CII Carbon, LLC (Rain) facility, and
air quality dispersion modeling based on the allowable limits.

DATES: This rule is effective on November 4, 2022.

ADDRESSES: EPA has established a docket for this action under Docket ID
No. EPA-R06-OAR-2017-0558. All documents in the docket are listed on
the https://www.regulations.gov website. Although listed in the index,
some information is not publicly available, e.g., 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. Publicly available docket materials are
available electronically through https://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT: Karolina Ruan Lei, EPA Region 6
Office, SO2 and Regional Haze Section (R6-ARSH), 214-665-
7346, [email protected]. Out of an abundance of caution for
members of the public and our staff, the EPA Region 6 office may be
closed to the public to reduce the risk of transmitting COVID-19.
Please call or email the contact listed here if you need alternative
access to material indexed but not provided in the docket.

SUPPLEMENTARY INFORMATION: Throughout this document ``we,'' ``us,'' and
``our'' means the EPA.

I. Background

    The background for this action is discussed in detail in our
December 7, 2021 proposal (86 FR 69210). In that document, we proposed
to determine that the St. Bernard Parish SO2 nonattainment
area failed to attain the primary 2010 one-hour SO2 NAAQS
under the CAA by the applicable attainment date of October 4, 2018.
This proposed determination was based upon consideration of and review
of all relevant and available information for the St. Bernard area
leading up to the area's attainment date of October 4, 2018, including
(1) emissions and monitoring data, (2) the state's air quality modeling
demonstration, which showed the emission limits and stack parameters
required at Rain, the primary source of SO2 emission in the
area, that were necessary to provide for the area's attainment, and (3)
Rain's available compliance records between the period when the Agreed
Order on Consent (AOC) limits became effective (August 2, 2018) and the
area's attainment date. The state's dispersion modeling is based on the
allowable limits in the August 2, 2018 AOC between Rain and the
Louisiana Department of Environmental Quality (LDEQ). Compliance with
those limits showed modeled design values in attainment of the
SO2 NAAQS, but close to the level of the NAAQS (i.e., with
little margin of safety). Rain, however, has demonstrated a pattern of
difficulty meeting these federally enforceable applicable
SO2 emission limits and stack parameters (memorialized in
its Title V permit and the AOC). Review of Rain's compliance record
provides evidence that emissions have exceeded those prescribed limits,
and that stack temperatures and flowrates have not met the parameters
present in the modeling, such as (1) reported deviations during the
period between the effective date of the limits and the attainment date
and (2) reported underestimation of emissions from the hot stack. As a
result of these difficulties in meeting the limits in the AOC, we
cannot determine that the area attained the standard by the attainment
date. EPA's final determination, described further in this action and
explained in our response to comments, relies on the same basis and
rationale that was used in our proposed determination.
    We received comments on the December 7, 2021 proposal from several
commenters including the state, community members and community groups,
and industry groups. In the following section, we are providing a
summary of responses to certain significant comments received on the
proposal. In subsections II.B through II.E of this action, we provide a
response to several community comments that while not germane to our
final decision here, serve to better aid and inform the public of
matters raised by such commenters. The response to comments (RTC)
document accompanying this action and found in the public docket for
this rulemaking contains these summaries and the full text of all of
the comments that the EPA received during the public comment period
from December 7, 2021, to January 13, 2022, our full responses to all
comments, and additional details on our responses that are not found in
this notice. After careful consideration of the public comments, EPA is
finalizing the December 7, 2021, proposed finding that the St. Bernard
Parish SO2 nonattainment area has failed to attain the 2010
one-hour SO2 NAAQS by the applicable attainment date of
October 4, 2018.

II. Response to Comments

A. Comments Opposed to EPA's Proposed Determination That the St.
Bernard Area Failed To Attain the SO2 NAAQS

    Several commenters opposed EPA's proposed determination that the
St. Bernard area failed to attain the one-hour SO2 NAAQS by
the applicable attainment date. These commenters, including LDEQ and
Rain CII Carbon (Rain), asserted that EPA should not determine the area
failed to attain but should instead find that St. Bernard Parish is in
attainment with the 1-hour SO2 NAAQS. These commenters
identified several categories of factors that they claim support
finding that the area did attain by the October 2018 attainment date.
These factors include: (1) the large reductions in emissions at Rain
and nearby sources, (2) the two monitors in the area have monitoring
levels below the NAAQS level, (3) the AERMOD modeling included in the
State Implementation Plan (SIP) demonstration was conservative and
demonstrated attainment, and (4) the facility has achieved a high level
of compliance with the limits in the attainment demonstration SIP.
    In the following parts of this subsection II.A, EPA summarizes each
of these factors as a separate group of comments and provides a
response, and then EPA summarizes and provides a response to the
commenters' general assessment that the combination of these factors
supports their claim that the area attained the 2010 SO2
NAAQS.
1. Emissions Reductions at Rain and Other Sources
    Comment: The commenters state that EPA's proposed rule fails to
consider the major improvements to air quality in St. Bernard Parish
that have occurred since 2013, which include (1) permitted and actual
emissions reductions from the Rain facility and (2) emissions
reductions from other SO2 sources (e.g., industrial, mobile,
and non-road) in and around St. Bernard Parish. For other
SO2 industrial sources, commenters specify that both
Chalmette Refining LLC (Chalmette Refining) and Valero Refining Meraux,
LLC (Valero Refining) had consent decrees with both EPA and LDEQ in
2006 and 2011, respectively, that have resulted in reducing actual
SO2 emissions from these two facilities by over 90% in the
last decade. Commenters also assert that EPA has promulgated
regulations to control fuel and engine standards to reduce
SO2 emissions from on-road and non-road engines for the last
15 years which caused mobile source SO2 emissions to
decrease significantly in the last decade. Commenters pointed to LDEQ's
November 9, 2017 proposed SIP as evidence that mobile and nonpoint
source emissions accounted for hundreds of tons of SO2
emissions in 2011 and have significantly decreased from that level in
the last decade. Additionally, the commenters state that the downward
SO2 emission trends show significant SO2
emissions reductions that have been sustained. As an example of this
downward SO2 emission trend, the commenters state that a
petroleum refinery (Phillips 66) in a nearby parish with past
SO2 emissions averaging 400 tons per year (tpy) of
SO2 in the past five years recently announced that it will
permanently shut down, which will provide additional air quality
improvements to the St. Bernard area. The commenters argue that EPA
should consider the downward SO2 emissions trends and the
significant reductions of actual SO2 emissions at these
sources in and around St. Bernard Parish as evidence that St. Bernard
area has attained the SO2 NAAQS, and that EPA failed to
discuss these reductions in any meaningful way in a weight-of-evidence
approach.
    Response: EPA disagrees with the commenter's assertion that it
failed to consider permitted, actual, and consent decree-based
emissions reductions. EPA recognizes that significant reductions in
SO2 emissions have occurred and that these reductions have
improved air quality. EPA, however, must consider all available
information in determining whether sufficient emission reductions
occurred to provide for attainment by the applicable attainment date of
October 4, 2018. In this case, and as detailed more in this section,
Rain had difficulty complying with its enforceable emissions limits and
stack parameters for certain operating scenarios. The modeled
attainment demonstration must be based on short term emissions limits
or potential to emit and compliance with these limits is necessary to
ensure attainment of the standard throughout the area.
    EPA considered all the available information during our review of
whether the St. Bernard area attained or failed to attain the
SO2 NAAQS by the attainment date, including information on
emissions reductions from SO2 sources in the area. In this
instance, the consent decrees and the LDEQ's attainment demonstration
modeling relied upon federally enforceable reductions in short-term
allowable emission rates. EPA acknowledges that there have been large
reductions in actual SO2 emissions from the Rain facility
and the two refineries in St. Bernard Parish. We note that Chalmette
Refinery and Valero Refinery both had previously entered into consent
decrees with the LDEQ and EPA that implemented new SO2
emissions limits, including reduction of the facilities' allowable
emission rates or Potential to Emit (PTE). As explained in more detail
in the TSDs that accompany EPA's separate, prior approval of the
attainment demonstration SIP for St. Bernard,\1\ EPA and LDEQ worked
together to identify the current emission limits that reflect the
reductions in short-term PTE/allowable emission rates for these two
refineries (Chalmette Refinery and Valero Refinery) which LDEQ relied
upon in its attainment demonstration modeling.\2\
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    \1\ In a May 29, 2019 final action, EPA approved the
nonattainment area SIP for the St. Bernard area, which also included
the area's attainment demonstration (84 FR 24712).
    \2\ EPA's Attainment Demonstration Supplemental TSD pages 14-18.
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    As discussed in more detail in response to a comment concerning the
modeling in the attainment demonstration (subsection II.A.3 of this
notice), EPA's 40 CFR part 51 Appendix W, Guideline on Air Quality
Models, requires the use of short-term PTE/allowable emissions when
modeling the major sources in the nonattainment area. Since the 1-hour
SO2 NAAQS is an hourly standard that is based on the three-
year average of the 99th percentile of the annual distribution of daily
maximum one-hour average concentrations, the potential exists to
violate the standard with relatively few modeled or monitored
exceedances. For this reason, EPA's guidance is to model the short-term
PTE/allowable limits for sources such as Rain, Chalmette Refinery and
Valero Refinery. LDEQ included revised short-term PTE/allowable limits
at Rain, Chalmette Refinery and Valero Refinery in its modeling for the
attainment demonstration. These revised limits properly account for the
allowable emission reductions by using the enforceable short-term PTE/
allowable emission rates based on the latest permit and consent decree
data in 2018 when the modeling was conducted.
    The commenters did not identify any additional significant changes
in enforceable short-term emission rates for the Rain, Chalmette, and
Valero facilities that were required in 2018 that should have been
included in the 2018 modeling. EPA acknowledges that there have been
actual and allowable emission reductions in the last decade and since
2016 and that the area's air quality has improved. However, these
reductions in allowable emissions for all

three facilities were factored into the attainment demonstration
modeling. Specifically, the modeling incorporated the most recent
permit limits that existed in 2018 and included reductions that had
already occurred from consent decrees for Chalmette and Valero
refineries. These reductions at the refineries were already in the
modeling that was used to analyze potential changes to Rain's February
2018 AOC and identify the new short-term emission limits and stack
parameters for Rain with which compliance was necessary to bring the
area into modeled attainment. Therefore, the final modeling scenarios
included the reductions necessary at Rain, including the emission
limits and stack parameter limits for Rain's 11 operational scenarios.
These emission limits and stack parameters were included in the August
2, 2018 AOC between LDEQ and Rain. LDEQ's attainment demonstration
modeling and SIP relied on these emissions limits as necessary for the
area to attain the NAAQS. EPA's finding of failure to attain is based
on all of the evidence before it, notably that the Rain facility has
been unable to comply with those AOC limits that were necessary to
demonstrate attainment of the NAAQS.
    EPA disagrees with the commenters' claim that EPA failed to
consider downward annual emissions trends and that these annual
reductions are evidence that the area has attained the NAAQS.
Reductions in longer term actual annual emissions are helpful, but
changes in short-term PTE/allowable emission limits and short-term
actual emissions are what is important for demonstrating and reaching
attainment of the 1-hour SO2 NAAQS. As explained earlier,
the reductions in allowable short-term emissions for all three
facilities were factored into the attainment demonstration modeling.
These short-term emission limits have the most influence on the 1-hour
SO2 NAAQS, as this standard is set to protect against acute
short-term exposure of SO2; this is the reason EPA's
modeling guidance \3\ specifies the use of short-term PTE/allowable
SO2 emission limits in determining maximum modeled design
values. We also note that any emission reductions that may have
occurred after the October 4, 2018 attainment date cannot be used to
support a determination of whether or not the area attained by October
4, 2018.
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    \3\ See 40 CFR part 51 Appendix W--Guideline for Air Quality
Models and Appendix A, Modeling Guidance for Nonattainment Areas of
the April 23, 2014 Guidance for 1-Hour SO2 Nonattainment
Area SIP Submissions, available in the docket for this action.
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    Commenter mentioned that EPA had not directly factored in further
reductions from federal measures for mobile and non-road emission
sources as part of EPA's determination. First, EPA would like to
clarify that the commenter misconstrued the potential degree of mobile
(on-road and non-road) emission reductions. The commenter asserted that
mobile and nonpoint source emissions accounted for hundreds of tons of
SO2 emissions in 2011 (specifically, nonpoint emissions of
702.22 tpy as provided in LDEQ's November 9, 2017 SIP); while this is
correct, EPA notes that mobile (on-road and non-road) emissions are
only a small portion of the emissions accounted for in nonpoint source
emissions as part of the National Emission Inventory (NEI), and the
nonpoint category includes other emission sources that did not have
reductions due to the federal measures cited by the commenter. EPA
notes that in that same SIP, the non-road and on-road SO2
emissions for the 2011 NEI emissions for St. Bernard Parish were only
1.31 and 2.35 tpy, respectively. Therefore, any reductions to these
relatively small emissions from mobile sources due to federal rules
would have a minimal impact on the overall inventory.
    Second, mobile source emissions are not explicitly modeled but are
included as part of the background concentration which is then added to
the modeled concentrations to result in modeled design values. The
background concentration added to the modeling is already low \4\ and
represents the impacts of all emission sources not explicitly modeled,
including some mobile source emissions, and these mobile source
emissions are only a small fraction of the SO2 sources that
make up the total background concentration added to the modeled values.
Therefore, any reductions of mobile source emissions due to federal
measures from 2012-2014 up until the attainment date in 2018 that were
represented in the background concentration would be expected to only
potentially result in a very small change in the background
concentration and would not be expected to significantly change the
maximum modeled concentration. See the RTC document for more detailed
discussion of mobile sources in the area and how the background
concentration was estimated.
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    \4\ On average a relatively low background value of 6.27 ppb.
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    Commenters argue that the Phillips 66 refinery plans to shut down
and that EPA should consider the future potential reductions in
emissions when determining whether the area has failed to timely attain
the NAAQS. LDEQ included Phillips 66 refinery, located approximately 27
km south of Rain, in the modeling provided as part of the 2018
attainment demonstration SIP.\5\ It was operating at the time and
Phillips' actual emissions were included in the attainment
demonstration modeling as a background source in 2018. The EPA
disagrees with the commenters, any emissions reductions that occurred
after Oct. 4, 2018 at Phillips or any planned future emission
reductions, including facility shutdowns, cannot be considered in
determining if the area failed to attain by the October 4, 2018
attainment date.
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    \5\ EPA's Attainment Demonstration Supplemental TSD pages 7-8,
14-16.
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2. Monitoring Data
    Comment: The commenters state that the St. Bernard area monitors
Meraux and Chalmette Vista show significant and continuous air quality
improvements in both the monitored design value (DV) for SO2
(which according to commenters now shows attainment) and the number of
exceedances of the one-hour SO2 NAAQS. Commenters indicated
that compared to data from the same monitors during the 2009-2015
period, there has been dramatic improvement to the air quality in St.
Bernard Parish due to the reductions in SO2 from multiple
sources, including the Rain CII Carbon's Chalmette facility.
Specifically, commenters indicate the Meraux monitor one-hour design
value for 2018-2020 is about 10 percent of the SO2 NAAQS and
the design value for the Chalmette Vista monitor for the same period is
close to half the 75-ppb standard. Commenters included DVs for both
monitors in St. Bernard Parish up to the 2018-2020 DVs to support their
statements. Commenters argue that EPA should consider these
improvements and downward trend of concentrations at the monitors,
including the number of exceedances and the overall design values, in
its determination as evidence that the St. Bernard area attained the
SO2 NAAQS, as this data must be considered as probative and
significant in any weight-of-evidence approach.
    In addition, EPA received several comments discussing the location
of the monitors and arguing against EPA's position in its proposed
determination that the monitors are not located in the area of maximum
concentration for SO2.

These comments are summarized in the following three paragraphs.
    One commenter argues that it is unlikely that air quality is
significantly different within St. Bernard Parish at other locations
due to the proximity of the monitors to the major industrial sources--
for example, the Chalmette Vista monitor is located close to Rain CII
Carbon and Chalmette Refining. Commenters state that if EPA cannot
consider monitoring on its own to determine that the St. Bernard Parish
area attained by the attainment date, it can use monitors in close
proximity to major sources as strong evidence that the area is in
attainment.
    EPA received comments that used the basis for the original siting
of the monitors in St. Bernard as a reason for why these monitors are
representative of air quality in the area and therefore indicative of
the area's attainment. These comments indicated that EPA did not
explain why the Chalmette Vista or Meraux monitors are not located in
the area of maximum concentration as EPA considered close proximity to
sources as a major factor when the agency approved the locations of
five new SO2 monitors in other parishes in Louisiana in
2016. In addition, based on prior SIP documents, commenters argue EPA
used the Chalmette Vista and Meraux monitors to designate St. Bernard
Parish as nonattainment with the 1-hour SO2 NAAQS.
    Another commenter criticized EPA's basis for its proposed
determination, stating that EPA ``relies heavily'' upon the argument
that the Chalmette Vista monitor is not located in the area of maximum
concentration. The commenter countered EPA's position by indicating
that the area of maximum concentration is located in the Jean Lafitte
National Historical Park and Preserve, Chalmette Battlefield, which is
a wide expanse of uninhabited land. Commenter continued that LDEQ has
argued in discussions with EPA that the Chalmette Vista monitor is
located in a neighborhood directly across from the Rain CII facility,
making it better suited toward the protection of the residents.
    Response: EPA considered and reviewed the Chalmette Vista and
Meraux monitoring data as part of our determination. While we take note
of the downward trends raised in the comments, we disagree with the
commenters' statements that the monitoring data is sufficient evidence
the area attained by the attainment date. As we stated in our proposed
action, although the one-hour SO2 design values at the
Chalmette Vista monitoring site located within the St. Bernard area
show a downward trend of SO2 concentrations less than 75 ppb
for the one-hour standard beginning with the 2015-2017 design value,
this monitor is not located in the area of maximum predicted
concentration, and therefore cannot be used, on its own, to determine
that the St. Bernard Parish area attained by the attainment date.
Monitors can only provide a measurement of the air quality at a
specific location and do not necessarily indicate whether the
SO2 standard has been attained throughout the area. The
commenters did not provide sufficient details but rather provided an
unsupported claim that monitoring or monitoring along with other
pertinent information should be enough to base a decision that the area
reached attainment.
    As included in our TSDs for approval of the attainment
demonstration SIP, we did note that monitored DVs had decreased at the
Chalmette Vista and Meraux monitors.\6\ We also note, however, in
Figure 6 of EPA's Supplemental TSD that the maximum modeled DV was to
the west of Rain with a value of 190.8 [micro]g/m\3\ (97% of the
NAAQS); Figure 6 also includes concentration isopleths in the area of
the Chalmette Vista monitor, indicating the modeled DV near the monitor
location was approximately 110 [micro]g/m\3\ which shows that the
Chalmette Vista monitor is not sited to pick up the maximum DV in the
area and is instead located in an area modeled to be approximately 58%
of the maximum modeled DV.\7\ From the modeling, it is clear that the
Chalmette Vista monitor and the Meraux monitor are not in the
anticipated areas of maximum modeled design concentrations, and that
contrary to the commenter's assertion, there are significant
concentration gradients near the Rain facility. This is a logical
result; when winds are blowing from the east, the emissions of the
Valero refinery and Chalmette refinery are in line with Rain, and
therefore, the emissions from all three sources combine to result in
the maximum concentrations being located to the West, downwind of Rain
(the largest emitter of the three sources). When the wind is blowing
Rain's emissions to the North towards the Chalmette Vista monitor,
emissions from Chalmette refinery or Valero refinery are not in
alignment such that emissions from these two facilities could combine
with Rain's emissions to result in a maximum monitored or modeled value
in the area around the monitor. For situations where winds are blowing
from the West and emissions from the three facilities overlap to the
east of the facilities, the emissions from the largest SO2
source (Rain) have already been transported several miles and will have
experienced dispersion; this causes (1) the concentrations to the east
of Valero refinery near the Meraux monitor location to not be as large
as when winds are blowing from the east and (2) the maximum area
concentrations modeled to be located to the west of Rain. Therefore,
the Chalmette Vista and Meraux monitors are not located in the area of
the expected maximum DV in the modeling domain and EPA cannot rely upon
the monitoring data alone to determine the area has attained; this is
the case even considering the proximity of the monitors to major
stationary sources of SO2 and other relevant information in
the St. Bernard area.
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    \6\ EPA's Attainment Demonstration Supplemental TSD pages 5-6.
    \7\ EPA's Attainment Demonstration Supplemental TSD pages 24-25;
EPA's Attainment Demonstration TSD including pages 35-36.
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    With regard to comments concerning LDEQ's siting of new
SO2 monitors in other parishes in Louisiana in 2016 based on
close proximity to sources, these monitors were sited for the purpose
of characterizing 1-hr SO2 air quality for designation
purposes under the Data Requirements Rule (DRR) \8\ and EPA provided
guidance \9\ to use modeling to identify the location or locations of
ambient SO2 concentration maxima to inform monitor siting.
LDEQ did site SO2 monitors in 2016 based on proximity and
modeling to try and identify the area where maximum DVs might be
monitored. However, monitor siting can be complicated, and siting of
monitors can be restricted by availability or accessibility of a
suitable location, including obtaining permissions from landowners and
finding necessary support services, such as power. These real-world
logistical constraints can sometimes make it impossible to site
monitors at specific locations that may be predicted by modeling to be
locations of expected maximum concentrations.
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    \8\ August 21, 2015, Final Rule, ``Data Requirements Rule for
the 2010 1-Hour Sulfur Dioxide (SO2) Primary National
Ambient Air Quality Standard (NAAQS),'' 80 FR 51051.
    \9\ SO2 NAAQS Designations Source-Oriented Monitoring
Technical Assistance Document, February 2016. Available in the
docket for this action.
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    The commenter specifically referred to LDEQ locating 5 monitors in
2016 around other facilities in Louisiana outside of St. Bernard Parish
as part of the DRR monitoring. The commenter believes that because
these monitors were located near the sources in those areas, and 4 of
these 5 monitors had

measured 2017-2019 DVs less than half of the NAAQS such that they were
eventually removed, that this information provides support that the
Chalmette Vista and Meraux monitors DVs are representative of the
maximum DV in the St. Bernard area since they were also located near
the source. As discussed elsewhere, the Chalmette Vista and Meraux
monitors were installed prior to the promulgation of the 1-hr
SO2 NAAQS, and no modeling was done at the time to confirm
if these monitors were near the location of the expected modeled
maximum design values whereas, as discussed, the goal of the DRR was to
locate monitors close to the point of maximum expected concentration.
The fact that DRR monitors in other areas were sited near a source(s)
based on modeling and other considerations and had low 2017-2019
monitored DVs does not support the comment that the Chalmette Vista
monitor and Meraux monitor are representative of the maximum DV in the
St. Bernard Parish and does not provide sufficient evidence that all
portions of the area meet the standard. Instead, available modeling
shows that the Chalmette Vista monitor and Meraux monitor are not in
the area of maximum projected concentrations and thus cannot provide
sufficient evidence that the entire area attained. We also note that
for all of these DRR monitored areas, there are differences that exist
between modeling of a historical period (2012-2014 in this case) and
the monitor data that was gathered from 2017-2019 including differences
in meteorology and emissions of the primary and nearby sources that can
result in large differences between modeled values \10\ and monitored
values, including the magnitude and location of the maximum
concentration in the area.
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    \10\ With the exception of the monitor sited in Calcasieu
Parish, the modeling performed in 2016 to site these monitors was
done in a normalized mode, such that absolute values were not
generated so it is unclear from the modeling results, whether the
absolute values were modeled above, near, or significantly below the
1-hr SO2 NAAQS.
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    As mentioned by the commenter, the Chalmette monitor was sited
prior to issuance of the DRR based on consideration towards
characterizing air quality in the Chalmette neighborhood near the
source, providing relevant data on population exposures, but was not
based on an evaluation of the location of the maximum ambient
concentrations in the area.\11\ Furthermore, the additional controls
installed, lower emission limits, and stack parameter conditions
(temperature and flow rate) captured in the August 2018 AOC for Rain
sources combined with the other enforceable reductions at other
facilities resulted in significant changes that impacted the dispersion
of emissions from Rain and the modeling results and where the maximum
modeled concentrations occur in the area. We also note that while the
Chalmette monitor data was the basis of the nonattainment designation
in 2013,\12\ that data showed that there were measured hourly
concentrations above the level of the standard at the monitor during
that time period (2009-2011) but did not provide any information as to
the location or magnitude of the maximum concentration in the Parish
and whether the monitor was located in the Parish's area of maximum
concentration. Even though a monitor may measure hourly concentrations
above the standard, it does not demonstrate that the monitor is sited
in an area of maximum concentration. In other words, it only
demonstrates that the concentration it measures is above the level of
the standard, and, absent other information, leaves open the
possibility that other locations in the area may be experiencing even
higher concentrations. Furthermore, since the area was designated
nonattainment in 2013, there have been changes such as (1) changed
stack parameters, (2) installation of controls, and (3) reductions in
emissions limits at Rain and other facilities which have resulted in
changes to the air shed and where maximum concentrations will occur as
of the October 4, 2018 attainment, thus further highlighting the need
to rely on modeling to identify the location of the maximum design
value in the St. Bernard Parish area.
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    \11\ Chalmette Vista and Meraux monitors began operations in
2006 and 2007 respectively and were not sited based on modeling for
the 2010 1-hour SO2 NAAQS, so neither monitor would be
expected to be representative of maximum 1-hour SO2
NAAQS.
    \12\ See 78 FR 47191 (August 5, 2013).
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    Commenter argues that the maximum modeled DV is located in the Jean
Lafitte National Historical Park and Preserve, Chalmette Battlefield,
that it is an uninhabited area, and that the Chalmette Vista monitor is
located in a neighborhood directly across from the Rain CII facility,
making it better suited toward the protection of the residents.
Depending on the model run for the different Rain operating scenarios,
the location of the modeled maximum concentration is in slightly
different locations, and in the Supplemental TSD, the maximum modeled
value was not located within the Chalmette Battlefield but further to
the West.\13\ Regardless of the exact location of the maximum modeled
DV, EPA's ambient air standards apply to the entire nonattainment area,
in all areas that are considered ambient air. Ambient air is defined in
40 CFR 50.1(e) as ``that portion of the atmosphere, external to
buildings, to which the general public has access.'' Presence of
permanent residences is not a condition of whether the NAAQS applies in
an area, and EPA's attainment demonstration and determination of
attainment is based on the NAAQS being met at all potential ambient air
locations in the nonattainment area regardless of population level.
While EPA acknowledges that the Chalmette Vista monitor may be better
suited towards determining exposure of some nearby residents, it is not
representative of concentrations of other neighborhoods in other nearby
areas, as we found modeled concentrations located at other populated
areas that were higher than values modeled at the Chalmette Vista
monitor. In conclusion, the Chalmette Vista monitor data is not
representative or determinative of whether the entire nonattainment
area has attained the NAAQS.
---------------------------------------------------------------------------

    \13\ See Supplemental TSD page 25 including Figure 6. Figure 6
provides modeled results for the Rain Cold Stack standalone high
operations scenario, and the maximum DV was located across the river
in Jefferson Parish near a neighborhood with permanent residents.
---------------------------------------------------------------------------

3. Attainment Demonstration Model Performance
    Comment: EPA received a number of comments on the attainment
demonstration's modeling for the St. Bernard area. Commenters argued
that the conservative nature of the modeling submitted by LDEQ is
evidence that EPA should consider as a factor when determining whether
the St. Bernard area attained the SO2 NAAQS. Specifically,
commenters indicated AERMOD modeling is conservative by nature because
it was based on conservative inputs, representative of reasonable
worst-case conditions. Commenters also stated AERMOD modeling typically
predicts impacts higher than air quality monitoring, often
significantly higher than nearby monitoring sites, and that prior
comments to LDEQ's proposed SIP reference studies that illustrate that
AERMOD overpredicts SO2 concentrations (see LDEQ EDMS DocID
10860978, pp. 47-171). Commenter summarized that AERMOD includes use of
allowable peak emissions instead of actual emissions and worst-case
meteorological data and is conservative

because of these factors, and EPA should weigh this conservativeness
with other factors in making its determination. Multiple commenters
indicated that despite the use of an overly conservative model, LDEQ's
modeling demonstrated that the proposed controls resulted in attainment
of the 1-hour SO2 NAAQS. A commenter also indicated that the
modeling used the maximum PTE and the likelihood that all three major
contributing sources would emit at their PTE at the same time is
minimal. Commenter also indicated that facilities' actual emissions
have consistently been below their PTE.
    Commenter indicated that other evidence instead supports, rather
than contradicts, the modeling results. Commenter referred to Table 2
in the Proposed Finding of Nonattainment, which shows the modeling
results that modeled the maximum potential to emit (PTE) of all the
major sources contributing to the ambient design values, including
three different operating scenarios for Rain, the largest
SO2 source in St. Bernard Parish.
    Commenter indicated the modeling essentially ``double-counted''
emissions from the out-of-parish, distant, Phillips 66 source at
Alliance, Plaquemines Parish. Citing the Supplemental TSD for our
approval of LDEQ's attainment demonstration, commenters argue the
actual 2017 emissions from Phillips 66 were included in the model as a
conservative measure even though accepted EPA protocols did not require
Phillips 66 emissions to be included. Commenters then argue that these
emissions were double counted when they were also accounted for in the
``background'' values from the Meraux monitoring data.
    A commenter claims that EPA's required modeling protocols result in
very conservative predictions of ambient SO2 levels (i.e.,
overpredicted levels), stating that under the EPA's SO2
NAAQS Data Requirements Rule (DRR), LDEQ placed ambient SO2
monitors in five locations outside the St. Bernard area that began
monitoring by January 1, 2017, and the modeling for these other areas
indicated that levels would be well above the 1-hour SO2
standard. However, as evidence that the modeling is very conservative,
commenter indicated that at four of these locations, more than three
years of monitoring data collected showed ambient levels at less than
50% of the standard, and pursuant to EPA's monitoring requirements EPA
subsequently approved discontinuation of monitoring at those locations,
referring to the LDEQ 2020 Louisiana Annual Network Monitoring Plan
submitted to EPA on April 5, 2020.
    Commenter argues that based on these other monitors not in St.
Bernard Parish, the modeled predictions of high ambient SO2
levels shown in the modeling done by LDEQ and EPA for St. Bernard
Parish is likewise very conservative. Commenter concluded that where
such modeling predicts attainment and such predictions are supported by
actual monitored design values at nearby monitors showing levels below
the model predictions, the modeled predictions should be accepted as
prima facie evidence of attainment.
    Commenter argues that although EPA characterizes the modeled values
in the SIP attainment demonstration as being ``close'' to the 1-hour
SO2 NAAQS, even the worst operational scenario had a design
value at least 2 ppb below the standard (3% below). Furthermore, some
other operational scenarios yielded worst case predictions that were
11% and 5% below the standard, respectively. The commenters seemed to
be indicating that there is some head room in the modeling results such
that any non-compliance with emission limits or stack parameters may
not lead to actual concentrations that would result in exceedances or
violations of the 1-hour SO2 NAAQS.
    Response: We disagree with the comments that the AERMOD model and
EPA's modeling protocols result in ``very conservative''
overpredictions of ambient SO2 concentrations. As discussed
in the proposed rule, LDEQ used the most recent version of AERMOD and
followed EPA's guidance for SIP modeling for SO2.\14\ The
attainment demonstration modeling is based on PTE/allowable emissions
(i.e., the maximum permitted amount) and stack parameters for different
operational stages at the Rain facility, including stand-alone
operations for the waste heat boiler and the pyroscrubber and
transition stages between the two modes of operation.\15\ Consequently,
the attainment demonstration modeling reflects the maximum level of
emissions and ambient concentrations that could occur while sources
meet the SIP emission limits and required stack parameters, as required
by the CAA and our regulations. When EPA approved this modeling
demonstration for this purpose, such demonstration was not the subject
of a challenge, and EPA is not reopening the fundamental conclusions
about the modeling that it previously reached in this action. Again,
the issue is Rain's inability to comply with the emission limits and
stack parameters in the attainment demonstration SIP which the
attainment modeling indicated were necessary for the area to attain.
---------------------------------------------------------------------------

    \14\ See Appendix A, Modeling Guidance for Nonattainment Areas
of the April 23, 2014 Guidance for 1-Hour SO2 Nonattainment Area SIP
Submissions, available in the docket for this action.
    \15\ 86 FR 69213.
---------------------------------------------------------------------------

    AERMOD is the regulatory air dispersion model \16\ for use in
assessing near field (within 50 kilometers) criteria pollutant ambient
air concentrations for air quality analyses for regulatory purposes.
AERMOD has been subjected to an extensive, independent peer review.
Analysis of AERMOD's performance with field study data sets indicates
that AERMOD performs best for elevated point sources such as Rain and
the other larger SO2 emission sources in the modeling and
provides maximum modeled design values with an acceptable degree of
accuracy. The result is a slightly conservative and protective
estimation of maximum modeled DVs for these types of sources, not, as
commenter characterizes it, an overestimation which always results in
monitoring showing attainment. While AERMOD might be slightly
conservative in model predictions, modeling for attainment
demonstrations cannot have tendencies to underestimate concentrations
as that would result in violations of air quality standards going
undetected and would not be protective of public health. EPA
promulgated AERMOD as the preferred model to characterize impacts from
emission sources for 1-hour SO2 maximum DV concentrations
(and several other NAAQS pollutants) in 2005 and it has been used in
numerous designations for SO2 and Lead, numerous attainment
demonstration SIPs for criteria pollutants such as SO2,
PM2.5, and Lead, as well as in numerous permit application
analyses. See the RTC document for full analysis of specific comments
on AERMOD modeling performance.
---------------------------------------------------------------------------

    \16\ 40 CFR part 51 Appendix W--Guideline for Air Quality
Models.
---------------------------------------------------------------------------

    EPA's 40 CFR part 51 Appendix W, Guideline on Air Quality Models,
requires the use of short-term maximum PTE/allowable emissions when
modeling the primary source(s) in the nonattainment area (see Section 8
including Table 8-1) including the source(s) that are being evaluated
for an emission limit. Since the 1-hour SO2 NAAQS is an
hourly standard that is based on the three-year average of the 99th
percentile of the annual distribution of daily maximum one-hour average
concentrations, it does not take many modeled or monitored

exceedances to result in violations of the standard. For these reasons,
it is necessary to model the short-term (hourly) maximum PTE/allowable
emission rate limits for sources such as Rain, Chalmette Refinery and
Valero Refinery. LDEQ's attainment demonstration SIP included revised
short-term PTE/allowable emission limits and stack parameters for Rain,
along with the short-term PTE allowable emission limits for Chalmette
Refinery, and Valero Refinery. It was these limits that Rain did not
comply with during certain periods making it not possible to find the
area had attained by its attainment date.
    Several commenters compared actual annual emissions to annual PTE/
allowable emissions and indicated that actual emissions have been lower
than PTE/allowable emissions at Rain, Chalmette Refinery, and Valero
Refinery. Regardless of annual actual emissions, the sources likely
operated at higher hourly emission rates much of the time and had the
legal authority to operate up to the maximum hourly PTE/allowable
emission rates. Moreover, at issue is that Rain, in fact, did not
comply at all times with its required allowable short-term emissions
limits and stack parameters in the AOC which the attainment modeling
showed was necessary for the area to attain the NAAQS.
    Contrary to the commenters' claims, we did consider how actual
emissions may have differed from what was modeled in our evaluation of
the evidence, including the modeling results. When relying on a
modeling demonstration based on allowable emissions for purposes of
determining attainment by the attainment date, EPA looks to the
emission limit(s) and any other limits (stack parameters in this case)
that were adopted and whether the relevant source or sources were
complying with those modeled limits prior to the attainment date. In
other words, EPA looks to whether the state has demonstrated that the
control strategy in the SIP has been fully implemented. One of the ways
to determine if the plan was fully implemented is to review compliance
records to determine if the control measures have been implemented as
required by the approved SIP. This is necessary because a modeling
demonstration based on allowable emissions alone is not sufficient to
verify factual air quality status without the supporting information on
compliance with those emission limits and associated stack parameter
limits. We discuss facility compliance in more detail in the following
section (subsection II.A.4). As explained in subsection II.A.4, because
emissions at times exceeded the allowable limits and/or stack
parameters failed to meet the minimum requirements that were modeled,
LDEQ's modeling is not conservative and actual concentrations would be
expected to be higher than LDEQ's modeling results. We note that Rain
also underestimated pyroscrubber emissions (discussed further in this
response and the next response) which would further contribute to
underestimation of actual concentrations when pyroscrubber emissions
occurred.
    In sum, from the available information, EPA cannot determine with
certainty that the area attained the NAAQS as the emissions and stack
parameters at times fall outside the limits and conditions that were
modeled in the approved attainment demonstration. The noted violations
of the permit limits or underestimated emissions would be expected to
result in higher concentrations than were modeled and may have resulted
in exceedances and violations of the one-hour SO2 NAAQS in
areas other than the monitored location.
    In our evaluation, we focused on the time period between adoption
of the AOC on August 2, 2018, and the attainment date of October 4,
2018. For that approximately 2-month period, Rain identified 7 days
where they were not in compliance with either emission limits and/or
stack parameter limits in the AOC.\17\ Modeling analyses, including
many exploratory model runs performed by EPA and/or LDEQ, were
conducted to help establish the 11 operational scenarios with
associated emission limits and stack parameter limits in the AOC. The
modeled concentrations were sensitive to changes in the stack
parameters of stack air flow and minimum temperature. Changes to these
factors impact the ground-level concentrations by changing how high the
plume lofts and how quickly it reaches ground levels. Decreases to
stack flow rate and/or stack temperature would be expected to result in
decreased dispersion and increases in ground-level ambient air
concentrations and potentially move where the maximum modeled
concentrations occur. Therefore, if actual air flow and/or stack
temperature is below the minimum values in the AOC that were modeled,
the maximum modeled design value in the attainment demonstration
modeling results is no longer conservative and is likely an
underestimation of the actual maximum DV due to the reduced dispersion
as a result of less than minimum stack flow or temperature. For the
different modeling scenarios in the attainment demonstration, Rain's
emissions were the largest contributor to the maximum modeled design
values in the modeling domain. Therefore, the described changes to
Rain's dispersion characteristics coupled with an underestimation of
actual pyroscrubber emissions (for scenarios with pyroscrubber
emissions) would be expected to increase the maximum modeled DVs and
could result in modeled DVs that are above the 1-hour SO2
NAAQS. On 6 of these 7 days, Rain reported emitting below the required
minimum stack flow rate for the pyroscrubber stack for transitional
scenarios.\18\ Emitting at flow rates below the minimum airflow
requirements would result in higher ambient air impacts from
pyroscrubber stack emissions and the maximum design value would be
expected to increase. A number of scenarios were established to model
the air quality impacts when Rain transitioned its operations from full
operation through the pyroscrubber stack to operation though the heat
recovery stack.\19\ Since in all of these transitional scenarios of
emissions, the emissions from Rains' pyroscrubber stack had a large
impact on the maximum modeled design values, the periods when Rain was
not meeting minimum stack parameters raise a real concern that the
attainment demonstration modeling results do not reflect the situation
that actually occurred and do not reflect a conservative assessment of
the actual maximum modeled design value at the attainment date. If
these non-compliance periods with lower flowrates and/or temperatures
were modeled, they would have a higher maximum modeled concentration
value than the AOC required stack parameters would allow for during the
same modeled period and would likely show a violation of the NAAQS.
Furthermore, as discussed elsewhere, pyroscrubber emissions were
underestimated and actual emissions, if modeled, would also result in a
higher maximum modeled concentration than the AOC emission limits would
allow for during the same modeled period and would likely show a
violation of the NAAQS.

Without knowing the exact parameters and pyroscrubber emissions we
cannot model these actual stack parameters and emissions and confirm
with certainty that the value would model a violation, but we do know
the modeling for the attainment demonstration was very sensitive to
stack parameters and pyroscrubber emissions such that it is likely that
these excursion periods would have resulted in some exceedances and
potentially violations of the NAAQS. Because of this, the EPA cannot
determine with certainty that the area attained the NAAQS. As discussed
further in our responses in other parts of this notice, the form of the
1-hour SO2 NAAQS is very sensitive to a small number of
exceedance or near exceedance hours within days each year (on the order
of 4 days a year, on average), so having 7 days of non-compliance in a
two-month period is concerning and threatens the ability to attain the
NAAQS.
---------------------------------------------------------------------------

    \17\ See deviations listed in the semiannual monitoring report
for July 1-December 31, 2018 included in the docket for this action.
    \18\ Transitional scenarios are operational scenarios identified
in the AOC that have emissions from both pyroscrubber and waste heat
boiler stacks.
    \19\ See EPA's Attainment Demonstration Supplemental TSD pages
20-27.
---------------------------------------------------------------------------

    As the commenter noted, some of the attainment demonstration
modeling for these transition scenarios resulted in DVs that were 11%
below the NAAQS (range of all transition stages was 5% to 15% below the
NAAQS) implying the modeling had some margin of safety. As discussed in
the next response (subsection II.A.4), the 2019 stack test results
indicate that pyroscrubber emissions have been underestimated by at
least 10% and up to approximately 60% at times,\20\ which would remove
much, if not all, of the head room even without factoring in dispersion
worse than what was modeled due to not complying with minimum stack
flow and temperatures.
---------------------------------------------------------------------------

    \20\ See Table 5 of the 2019 Stack Test Report, available in the
docket for this action.
---------------------------------------------------------------------------

    In addition, when the facility is in its transition stages, the
current equation to determine air flow volume through the hot stack
underestimates the amount of flow, resulting in further underestimation
of pyroscrubber stack emissions. We note that Rain has recently
proposed changes to the emissions equation and stack flow equation are
based on Rain's analyses of the existing equations to stack tests in
2019-2021. This change in the emissions equation and stack flow
equation proposed by Rain is not before EPA or LDEQ for official
review. We note that it does support EPA's concerns that the emissions
and stack parameter limits in the August 2, 2018 AOC were not
implemented at all times and actual emissions may have exceeded the
allowable emission rates at a higher frequency than reported in the
compliance reports. If these different operating parameters and/or
higher emission rates were modeled, the maximum modeled design values
would be higher, and, therefore, the existing approved modeling results
are not conservative. Without knowing the exact parameters and amount
of higher pyroscrubber emissions we cannot model these actual stack
parameters and emissions, but we do know the modeling for the
attainment demonstration was very sensitive to stack parameters and
pyroscrubber emissions such that it is likely that these excursion
periods would have resulted in some exceedances and potentially
violations of the NAAQS. Because of this, EPA cannot determine with
certainty that the area attained the NAAQS.
    The Phillips 66 refinery (Phillips) south of Rain was included in
the modeling that LDEQ provided as part of the attainment demonstration
SIP and is located approximately 27 km south of Rain.\21\ Phillips was
operating at the time, and Phillips' actual emissions were included in
the modeling as a background source at the time the attainment
demonstration was submitted in 2018. Since the maximum modeled
concentrations were to the West of Rain, even if the background monitor
value included any impacts from Phillips 66, the modeled impacts from
Phillips emissions would not be transported to add to the maximum
modeled concentration; this is due to Phillips not being located upwind
(East or West) of Rain, which means there is no double-counting of
Phillips emissions impacts to the maximum modeled DVs in the modeling
for the different operational scenarios.
---------------------------------------------------------------------------

    \21\ EPA's Attainment Demonstration Supplemental TSD pages 7-8,
14-16, found in the docket for this rulemaking. Modeling results in
modeling files for other operating scenarios are included in the
Supplemental TSD.
---------------------------------------------------------------------------

    See the RTC and our response to the previous comment in subsection
II.A.2 about monitors in other areas and how the information provided
is not sufficient to understand how modeled concentrations for the
2012-2014 period and monitored values from 2017-2019 compare.
4. Facility Compliance
    Comment: The commenters state that EPA should consider the overall
level of compliance by the Rain facility with its Title V permit and
the AOC agreement in its determination of whether the St. Bernard area
has attained the SO2 NAAQS. The commenter disagrees that the
Rain facility has not achieved a high degree of compliance with the
SO2 emissions limits set forth in its current Title V
Operating Permit and the AOC agreement. Commenter continues that Rain
has operated below their sitewide permitted SO2 emission
limit most of the time for the past four years in addition to operating
below permitted limits of individual sources most of the time. The
commenter also claims that the compliance history of the waste heat
boiler/baghouse and the pyroscrubber stack with the permit and AOC
limits in 2020 and 2021, coupled with the relatively few excursions of
operating parameters that occurred for the period August 2, 2018,
through October 4, 2018, show that EPA's justification for its proposed
determination is inadequate.
    In reference to annual emissions, the commenter indicated the
facility's permitted SO2 emissions for the entire site
(i.e., all sources of SO2 emissions at the facility) are
currently 2,626 tpy and that Rain has operated well below this sitewide
annual total over the past four years in addition to annual
SO2 limits for individual sources. Commenter continued that
the current Title V permit also includes short-term SO2
emissions limits for the waste heat boiler/baghouse (EQT 0003) and the
pyroscrubber stack (EQT 0004). The waste heat boiler/baghouse (EQT
0003) has a maximum 510.00 lb/hr SO2 limit and the
pyroscrubber stack (EQT 0004) has a maximum 2,022.70 lb/hr
SO2 limit.
    Commenter indicates that the AOC Agreement, entered between LDEQ
and Rain CII Carbon and effective on August 2, 2018, includes 11
distinct emissions limits for SO2 associated with the waste
heat boiler/baghouse (EQT 0003) and/or the pyroscrubber (EQT 0004).
Commenter stated that these emissions limits vary depending on
operating conditions of the rotary kiln and associated process
equipment and was established based on flow and temperature parameters.
Additionally, the AOC Agreement also includes various monitoring,
reporting, recordkeeping, and testing requirements for the waste heat
boiler/baghouse and the pyroscrubber to ensure compliance with the
underlying emission limits. Commenter asserted that an excursion of
stack parameter limits such as flowrate or temperature parameter (for
one of the 11 distinct emission limits) does not necessarily equate to
an exceedance of an SO2 emissions limit and therefore EPA
does not know for sure that an exceedance of the NAAQS level would have
resulted.
    Commenter also provided information about the waste heat boiler/
baghouse (EQT 0003) operations for 2020 and first half of 2021,
indicating it was only out

of compliance for 30 hours in 2020 and 15 hours in the first half of
2021 and that it was in in compliance more than 99.6% of the time it
operated. Commenter noted that the Title V permit limits the
pyroscrubber stack (EQT 0004) to a maximum of 500 hours/year on a 12-
month rolling average and that the facility has not exceeded that
limit. Regarding pyroscrubber stack operations for 2020 and the first
half of 2021, commenter indicated Rain was only out of compliance for
72 of 7,234 hours in 2020 and 78 out of 4,018 hours for the first half
of 2021 resulting in compliance 99.0 percent of the time in 2020 and
98.1 percent of the time in the first half of 2021.
    Commenter summarized that except for very limited periods, the Rain
facility has not exceeded the short-term SO2 emissions
limits over the past four years, indicated by the facility's Title V
semiannual deviation reports and annual compliance certifications.
Commenter noted that the Title V permit requires Rain to operate and
maintain a SO2 continuous emissions monitor (``CEMS'') for
the waste heat boiler/baghouse (EQT 0003) to ensure compliance with
these limits (See, Specific Requirement Nos. 55-58 and 80 in Title V
Permit No. 2500-00006-V4).
    Commenter (Rain) also indicated EPA should consider the pending
amendment to the currently effective AOC Agreement entered on August 2,
2018. Commenter indicated that Rain has conducted performance tests on
the pyroscrubber stack on March 8-9, 2018, and July 7-8, 2018, and
after implementation of the AOC Agreement. Rain CII Carbon conducted
additional performance tests on March 13-14, 2019, July 22-23, 2020,
and September 15-19, 2021. Based on these performance tests, Rain has
proposed an amendment to the AOC Agreement that would revise certain
flow and temperature operating parameters. Commenter continued that
Rain's proposed amendment, currently under review by LDEQ and
preliminary review by EPA, will further reduce the self-reported flow
and temperature excursions for the waste heat boiler/baghouse and
pyroscrubber emissions points. Commenters assert that EPA should take
these pending proposed changes to the AOC Agreement into account as a
part of its determination whether the area attained the 2010
SO2 NAAQS.
    Commenter LDEQ indicated it would concede that Rain has not
adequately met the emission limits in the AOC. However, LDEQ then
claims that all equations used to establish those limits were based
upon theoretical modeling scenarios contrived from the facility's
operations and, therefore, it is difficult to predict every possible
operating combination for this facility. LDEQ argues that modeling the
periods when the facility did not meet the established limits would
present a better picture of whether the area was attaining, rather than
assuming that the limited number of modeled combinations are the only
possible combinations which would pass modeling. LDEQ stated that it
continues to model new combinations of emission limits and stack
parameters for Rain's proposed amendment to the AOC Agreement entered
on August 2, 2018, and LDEQ and EPA \22\ are currently providing
feedback on those elements. LDEQ indicated that there are numerous
variations of operating parameters that result in passing models with
new stack operating parameter ranges and revised emission limits that
are under review.
---------------------------------------------------------------------------

    \22\ The EPA wishes to clarify that this language summarizes
what the commenter stated. The EPA has not received a formal
submittal from LDEQ of a revised AOC. The EPA is only providing
preliminary, early engagement support here as it does with all
technical matters when requested by the state.
---------------------------------------------------------------------------

    Response: With respect to comments that EPA should consider the
compliance period as a whole from 2017 through 2021, EPA disagrees. EPA
is required to determine if the area's air quality attained or did not
attain by the October 4, 2018, attainment date. As part of that
determination, EPA considers whether control measures approved in the
attainment SIP were fully implemented by that date. In our proposal, we
provided evidence that Rain has struggled to meet the SIP-approved AOC
limits in the period up to the October 4, 2018 attainment date to
support our proposed finding of failure to attain. We note that the
commenters have provided additional information that indicates the Rain
facility has continued to have non-compliance periods past the October
4, 2018 attainment date and that Rain is working with LDEQ and EPA to
revise the emission rate limits and stack parameters limits for
different operating scenarios, modify the emission calculation formula
for the pyroscrubber stack, and complete revised modeling incorporating
these proposed changes.\23\ (We note that when referring to the waste
heat boiler/baghouse (EQT 0003) we will shorten to ``waste heat
boiler'' and for the pyroscrubber (EQT 0004) we will shorten to
``pyroscrubber.'') While the period following the October 4, 2018
attainment date is not the basis for EPA's final determination, this
additional information is illustrative that Rain did not demonstrate
full compliance with the August 4, 2018 AOC limits both in the period
up to October 4, 2018, and after October 4, 2018, which further
supports EPA's final determination that the attainment demonstration
SIP for St. Bernard Parish that EPA approved had not been fully
implemented. This EPA approved attainment demonstration SIP included
necessary requirements for the Rain facility that formed the basis of
the modeling demonstration in the SIP and EPA's approval.
---------------------------------------------------------------------------

    \23\ See deviations in 2021 first half Compliance report, 2021
Stack Test report, and Email (with attachments) from LDEQ to EPA on
December 8, 2021, that provided updated analysis of pyroscrubber
emission formula compared with stack test data, proposed new
emission and stack parameter limits or to be included in a future
AOC revision, and updated modeling. These are included in the docket
for this action.
---------------------------------------------------------------------------

    With respect to the comment that Rain had complied and been below
the annual emission limits for the last four years (facility total and
unit limits) we note that this is not of central importance in
determining if the area has attained the 1-hour SO2 NAAQS.
As discussed in Section II.A.2, determination of attainment could be
based on as few as 12 hours that have modeled/monitored exceedances or
near exceedances at a receptor/monitor in a 3-year period.\24\
Compliance with annual total emissions does not take into account short
term emission rates variation and whether emission limits (defined by
certain stack parameter regimes) are being complied with for all
operating hours. Therefore, compliance with annual tpy emissions is not
germane to determining if the area has attained. Again, the form of the
standard is such that as few as 12 hours or less of modeled exceedances
or near exceedances could result in a modeled DV that does not attain
the standard; therefore, even a small number of short periods of non-
compliance with an emission limit or the required stack parameters can
result in a violation of the standard.
---------------------------------------------------------------------------

    \24\ The 1-hour SO2 Design Value is an average of the
yearly 4th High maximum daily 1-hour SO2 value of each
year, thus the DV is based on 12 values at a receptor/monitor that
are either exceedances or near the standard that when the average of
3 consecutive years results in a DV that violates the 1-hour
SO2 NAAQS.
---------------------------------------------------------------------------

    Prior to LDEQ's attainment demonstration SIP proposal in 2017 and
leading up to the revised limits in the August 2, 2018 AOC; EPA, LDEQ,
and Rain continued to conduct modeling to refine the operational
scenarios and identify emission limits for each scenario that were
specific to stack volume flow ranges and temperature ranges because the
modeling was very

sensitive to the combination of emissions and the stack parameter
ranges; outside of the specific stack parameters for these operational
scenarios, the emission rates would often model nonattainment.\25\ The
revised August 2, 2018 AOC established revised emission limits with
specific temperature ranges and stack flow ranges that Rain believed
they could comply with. These limits are not theoretical ranges as they
were based on the combination of previous stack tests and input from
Rain, which led to established ranges that cover the combinations of
emissions and stack parameters that could realistically occur. The
stack parameter ranges were modeled to establish what emission limits
would not result in modeled violations (DVs above the 1-hour
SO2 NAAQS), and the stack parameters define what is the
applicable emission limit. These updated AOC limits in the August 2,
2018 AOC and attainment demonstration modeling results, highlight the
need for Rain to fully implement and achieve strict compliance with the
emissions limits and associated stack parameter ranges in order for St.
Bernard Parish to attain the NAAQS. We also note that prior to August
2, 2018, Rain was not operating in compliance with the limits in the
previous AOC, and this was a principal reason for the establishment of
new limits in the revised August 2, 2018 AOC.
---------------------------------------------------------------------------

    \25\ See TSDs and other materials in EPA's approval of LDEQ's 1-
hour SO2 attainment demonstration SIP for St. Bernard
Parish in the docket for this action (Docket No. EPA-R06-OAR-2017-
0558).
---------------------------------------------------------------------------

    Commenters did not contest that Rain was not in compliance with AOC
limits for 7 days in the period from August 2, 2018, through October 4,
2018; commenters only argued that the period of noncompliance was a
short amount of the time, and that the facility was in compliance most
of the time. However, EPA would again like to emphasize that given the
form of the 1-hour SO2 standard discussed earlier, a very
small number of periods of non-compliance with the established AOC
limits (as few as 1 hour per day for 4 days in a year, on average) can
result in modeled and/or monitored violations, and, therefore, having 7
days of non-compliance in less than 2 months can result in several
modeled exceedances of the 1-hour SO2 NAAQS. The model
demonstrating attainment did not assume compliance with the modeling
parameters 90% of the time or the majority of the time but all of the
time. Modeling results were sensitive to stack parameters and emission
rates such that any time the facility was out of compliance there is a
high likelihood that an exceedance could occur. Furthermore, as
discussed in more detail later in this response, there were likely more
times that the facility was not in compliance in the period from August
2, 2018 through October 4, 2018 that were not identified due to
underestimation of emissions and/or uncertainty in estimated flow
rates. We also note that prior to August 2, 2018, Rain was not
operating in compliance with the limits in the previous February 2018
AOC that were also based on different emission rate limits for
different stack parameters operational ranges.
    Commenter included details about the number of hours of non-
compliance for 2020 and first half of 2021 and summarized that Rain was
only noncompliant a relatively small percentage of the time during that
period. EPA included Rain's 2018 through 2020 semi-annual monitoring
reports, where Rain reported non-compliance periods, in the docket for
this rulemaking's proposal action. Since the commenter referred to the
2021 semi-annual monitoring report for the first half of 2021, we are
also including that report in the docket for this action. While the
compliance record with AOC limits since October 4, 2018 is not the
basis for our determination of whether the area has attained, it is
informative to note that the facility continues to have a number of
hours and days where it fails to comply with the August 2, 2018 AOC
limits.\26\ In 2019, either emissions and/or stack parameters from the
waste heat boiler stack were not in compliance with the AOC for 21
hours over 10 days, and either emissions and/or stack parameters from
the pyroscrubber stack were not in compliance for 63 hours over 12
days. In 2020, the waste heat boiler limits were not in compliance for
30 hours over 12 days, and the pyroscrubber limits were not in
compliance for 72 hours over 14 days. For the first half of 2021, the
waste heat boiler limits were not in compliance for 16 hours over 7
days, and the pyroscrubber limits were not in compliance for 78 hours
over 12 days. We note that the pyroscrubber is limited to operating 500
hrs/year, so 72 hours in 2020 reflects that it operated at least 14% of
the time not in compliance (14.4% based on assumption that it operated
up to the allowed 500 hours in 2020). These periods of non-compliance
with emission limits and/or stack parameter limits in the August 2,
2018 AOC occur at a frequency that can result in nonattainment and
shows the area has failed to fully implement the necessary measures
prescribed in the EPA approved nonattainment area SIP.
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    \26\ See deviations listed in semiannual monitoring reports for
2018. We also note as that the source continued to experience
deviations in 2019, 2020, and 2021. The semiannual monitoring
reports for 2018, 2019, 2020, and first half of 2021 as well as the
2019, 2020, and 2021 stack test reports are available in the docket
for this action.
---------------------------------------------------------------------------

    While commenters de-emphasize the hours of non-compliance and non-
compliance with stack parameter limits, these stack parameter limits
were based on modeling conducted with these values and associated
emission limits for each specific scenario, and non-compliance with
stack parameters does result in non-compliance with the AOC limits that
were approved in the attainment demonstration SIP. Non-compliance with
stack parameter limits creates a situation where the facility's
emissions are occurring with dispersion parameters outside what was
modeled and that are necessary to demonstrate attainment. For example,
for a number of the non-compliant periods, the calculated flow rates
for the pyroscrubber stack did not meet the AOC requirements in the
August 2, 2018 to October 4, 2018 period, indicating that pyroscrubber
stack emissions were released at lower velocities than modeling
indicated was acceptable when the flow rates limits were established.
Periods of non-compliance with stack parameters is consequential, as
lower flow velocities and/or lower stack temperatures result in less
dispersion which can result in higher ground-level concentrations than
modeled. When this is coupled with pyroscrubber emissions that are more
than the allowed limit this also can result in higher ground-level
concentrations than what was modeled.
    When relying on a modeling demonstration based on allowable
emissions for the purposes of determining attainment, the EPA looks to
whether the emission limit and other limits were adopted and whether
the relevant source or sources were complying with those modeled limits
prior to the attainment date. That is, when determining attainment by
the attainment date using air quality modeling of allowable emissions,
EPA looks to whether the state has demonstrated that the control
strategy in the SIP has been fully implemented (in other words,
ensuring that compliance records demonstrate that the control measures
have been implemented as required by the approved SIP). This is
necessary because a modeling demonstration based on allowable emissions
is not itself sufficient to show factual timely attainment without

supporting information demonstrating compliance with emission limits
and associated stack parameter limits.
    We note that in our proposal we referred to Rain's 2019 stack test
report regarding pyroscrubber stack emissions (Rain referred to this as
the ``hot stack'') which indicated that Rain found that ``the AOC hot
stack equation underestimates hot stack emissions during most of the
transition from hot stack to cold stack'' and ``[d]uring no hour did
the combined flue gas flow and temperature meet the description of any
transition stage.'' The report then states ``the AOC limits and
conditions do not reflect actual emissions conditions and it is
difficult to identify the appropriate transition stage,'' before
recommending that the August 2018 AOC's flue gas flow rates,
temperatures, and emissions limits for transitions stages 1, 2, and 3
be replaced with new conditions.\27\ This 2019 stack test was the first
annual stack test as required by the August 2, 2018 AOC and provides a
comparison of calculated emissions and flowrates for the pyroscrubber
stack to actual measured values. Comparison of the calculated
SO2 hot stack emissions to the measured hot stack emissions,
shows that actual emissions are underestimated during the transition
and were approximately 50% to 60% higher than calculated values for
most hours of the transition.\28\ The stack test also shows that the
calculated hot stack flow rate is at times higher than what was
measured during hot stack alone operations and during transition
stages. Rain found that the flow rate equation ``both overestimates and
underestimates hot stack gas flow rate.'' This stack test demonstrates
that not only have emissions been underestimated during the transition
periods, but the stack parameters fell outside of the modeled
transition stage requirements in the AOC. From the available
information, EPA cannot determine with certainty that the area attained
the NAAQS as the emissions and stack parameters at times fall outside
the limits and conditions modeled in the approved attainment
demonstration. The noted violations of the AOC limits and
underestimated emissions have likely resulted in exceedances and
potentially violations of the SO2 NAAQS in areas other than
the monitored location.
---------------------------------------------------------------------------

    \27\ See the 2019 Stack Test Report, available in the docket for
this action.
    \28\ See Table 5 of the 2019 Stack Test Report, available in the
docket for this action.
---------------------------------------------------------------------------

    Commenter indicated that EPA should take proposed changes to the
AOC being developed by Rain into account as a part of its final rule.
EPA is currently involved in the preliminary review of Rain's potential
revisions to the AOC, including revisions to the emission formula that
Rain uses to calculate emissions from the pyroscrubber stack and
potential changes in how flow rate is determined for the pyroscrubber
stack and revised modeling using these proposed changes. However, we
cannot base a final decision of attainment based on such proposed
revisions not officially before us for review as well as there
continues to be uncertainty over the effectiveness of such changes and
compliance therewith. While our decision is based on whether St.
Bernard Parish attained by October 4, 2018, we do note in our proposal
that based on the 2019 stack test, Rain had indicated that their
pyroscrubber emission formula underestimates emissions. The 2019 stack
test also showed that stack flow equations were overestimating and
underestimating pyroscrubber stack flow. We also note that the
additional stack tests in 2020 and 2021 coupled with pending potential
AOC revisions proposed by Rain that EPA and LDEQ are preliminarily
reviewing, while not the basis or rationale for our decision making,
includes additional deviations indicating that Rain continued to have
difficulty complying with the limits in the August 2, 2018 AOC after
the attainment date had passed. The proposed revisions to the emissions
formula for the pyroscrubber indicate that estimated emissions should
have been higher than those calculated with the formula used for
determining compliance since August 2, 2018. This indicates there may
have been more times that pyroscrubber emissions did not comply with
the AOC limits.\29\ The stack tests indicate that pyroscrubber stack
flows were being overestimated by the equations some of the time, which
creates a concern that the attainment modeling is not conservative and
underestimates actual maximum concentrations. Overestimation of
pyroscrubber flow means actual conditions had lower stack velocities
and less dispersion, resulting in actual concentrations higher than the
maximum modeled values. Stack tests also indicate some periods when the
stack parameter equation underestimates flow, and because the flow rate
is used to identify the transition stage and applicable emission rate,
this could result in a different transitional stage being identified
with different emission limits than the actual transitional scenario
the pyroscrubber stack is operating within. Misidentification of the
operating stage and applicable limits could result in additional
periods of noncompliance that were not identified and higher
concentrations than were modeled for that stage. These issues highlight
the implications of the underestimation of maximum concentrations
created by the underestimation of pyroscrubber emissions and
overestimation or underestimation of pyroscrubber stack parameter
equations used in determining compliance during the period prior to
October 4, 2018. Underestimating emissions and mischaracterizing the
actual pyroscrubber stack flow would likely also result in more periods
of non-compliance than was reported, further indicating that the limits
in the attainment demonstration SIP had not been fully implemented by
October 4, 2018.
---------------------------------------------------------------------------

    \29\ Email (with attachments) from LDEQ to EPA on December 8,
2021, that provided updated analysis of pyroscrubber emission
formula compared with stack test data, proposed new emission and
stack parameter limits or to be included in a future AOC revision,
and updated modeling, available in the docket for this action.
---------------------------------------------------------------------------

    Commenter asserted that an exceedance of stack parameter limits or
emission limits does not automatically lead to exceedances or design
values above the SO2 NAAQS and actual emissions and stack
parameters of non-compliance periods should be modeled explicitly to
determine if the specific non-compliance periods would result in
exceedances or design values above the SO2 NAAQS in
determining if the area failed to attain. As discussed earlier in this
action and in previous actions, the modeling was very sensitive to the
combination of stack air flow, temperature and emission rates, and
required 11 different operational scenarios to be able to model the
full range of operations of the Rain facility. The stack parameter
ranges for each operational scenario were developed based on stack test
data and exploratory modeling and where it showed potential modeled
violations, emission limits were further reduced. The 11 operating
scenarios were developed and refined with several iterations leading up
to the August 2, 2018 AOC because initial modeling of worst case
emissions and stack parameters for all flow ranges of the pyroscrubber
and/or waste heat boiler stack resulted in modeled violations. The 11
operating scenarios were developed to try and give operational
flexibility to Rain and still have modeling that demonstrated
attainment. The facility has struggled to comply with these 11
operational scenarios and identified 7 days in the period of August 2,
2018, through

October 4, 2018, where the facility was not in compliance with the
August 2, 2018 AOC limits.\30\ As indicated in the proposal, part of a
determination of whether the area has reached attainment is whether
there are limits (emission limits and stack parameter limits) in place
that have been fully implemented that demonstrate modeled attainment.
In this case there was an AOC in place for this roughly 2-month period,
but the limits were not being complied with to indicate that the
control strategy in the SIP had been fully implemented and, therefore,
that the area reached attainment. In addition to the identified periods
of non-compliance in the 2018 report, we also identified that the
pyroscrubber emissions were underestimated, and pyroscrubber stack
flows were over- and under-estimated, which could lead to mis-
identifying the appropriate transition stage and emission limits, and
these factors indicate that additional periods of non-compliance were
possible during that 2-month period than what was reported. As
discussed elsewhere in our responses, Rain has continued to have more
than a dozen days per year (2019 and 2020) that they identified that
did not comply with the August 2, 2018 AOC limits, and Rain has
requested to revise the emission formula for the hot stack and also
change the equation for determining stack parameters and emission
limits for the operational scenarios and further revise the limits in
the August 2, 2018 AOC. This information continues to support our
position that the August 2, 2018 AOC limits were not fully implemented
and complied with prior to the October 4, 2018 attainment date and
periods of non-compliance have continued to occur.
---------------------------------------------------------------------------

    \30\ See deviations listed in semiannual monitoring reports for
2018.
---------------------------------------------------------------------------

    EPA disagrees that modeling of the 7 days (when Rain did not comply
with the August 2, 2018 AOC limits) is appropriate or possible based on
several factors. Given the observed sensitivities of the modeling, it
is likely that modeling actual emissions or parameters would result in
modeled exceedances. The exact stack parameters and emission rates for
the Rain sources are not available to be modeled. Nor are exact
emission rates for many sources at Chalmette and Valero refineries. As
discussed elsewhere in responses, Rain is requesting changes to the AOC
including changes to the formula for calculating emissions from the
pyroscrubber stack that would result in higher emissions being
calculated and also potentially changing how pyroscrubber flow rates
and temperatures are derived, and the combination of these proposed
changes could increase estimated emissions from the pyroscrubber when
in transitional stages by 27%. These changes indicate that pyroscrubber
emissions were underestimated in the past due to the emission equation
and due to underestimated pyroscrubber stack flow, including during the
period from August 2, 2018, through October 4, 2018, and as a result
periods of non-compliance may have been underestimated. The revised
emission formula is under review by LDEQ \31\ and the formula could
change further, so there is not an accurate way to estimate
pyroscrubber emissions for the 7 days of non-compliance periods (from
August 2, 2018, through October 4, 2018). Similarly, there is
uncertainty in the estimated pyroscrubber flowrates with a potential to
overestimate and underestimate the actual flowrates which also results
in changes to how much the pyroscrubber stack is emitting. A revised
estimation methodology for pyroscrubber stack parameters is also
currently under review by LDEQ \32\ as part of the proposed AOC
revisions. With uncertainty about what the actual emissions were during
these non-compliance periods and uncertainty as to actual stack
parameters, it is not feasible to try and model the periods of non-
compliance. Moreover, since emissions were being underestimated some of
the time with the pyroscrubber formula, and the pyroscrubber flowrates
were overestimated/underestimated, there could also be more periods
that the facility was not in compliance in the period from August 2,
2018, through October 4, 2018.
---------------------------------------------------------------------------

    \31\ EPA is so far only doing preliminary, early engagement
support here per the state's request, as any revised AOC is not
officially before EPA for review.
    \32\ Id.
---------------------------------------------------------------------------

5. Overall Assessment
    Comment: EPA received a number of comments opposed to EPA's
proposed determination that the St. Bernard area failed to attain the
one-hour SO2 NAAQS by the applicable attainment date.
Commenters indicated that EPA should find that St. Bernard Parish did
attain based on all the available information. Some of these commenters
listed their assessment of several categories of factors that they
indicated when taking all of them into account provided overall support
that they thought that the area had reached attainment by the October
2018 attainment date and EPA should weigh all these categories of
factors and conclude the area did reach attainment. We have described
these factors in more detail elsewhere and provide an additional
summary here. These factor categories that the commenters raised
include (1) the large reductions in emissions at Rain and reductions in
emissions at other nearby sources, (2) the two monitors in the area
both have monitoring levels below the NAAQS level, (3) the AERMOD
modeling that was included in the SIP demonstration was conservative
for several reasons and demonstrated attainment, (4) the facility has
achieved a high level of compliance with the limits in the attainment
demonstration SIP with only a small amount of hours not in compliance,
and (5) EPA should consider compliance information since October 4,
2018 and also proposed revisions to the AOC and revised modeling. See
the comments in subsections II.A.1 through II.A.4 for a summary of the
major subjects that commenters are asking EPA to weigh in making EPA's
determination of whether or not the area attained by the attainment
date. Overall, several commenters indicated that these factors should
be considered in an overall weight-of-evidence that supports their
comments that EPA should determine the area did attain.
    In addition, commenters alleged that in EPA's proposed
determination, EPA rejected or ignored actual data from the monitors in
St. Bernard Parish when it factored in modeling and compliance data.
Commenters argued that EPA's position in its proposed determination is
based on ``conjecture'' and not rationally connected to any evidence.
Commenters also stated that while EPA cited potential issues with
Rain's compliance with the values used in the modeling, it did not
attempt to quantify those impacts, nor correlate any issues of
compliance problems with any actual impact at the ambient monitoring
locations. Commenters continued that EPA's failure to do so results in
an arbitrary, unsupported determination that the air quality in the
parish did not meet the 1-hour SO2 NAAQS.
    Response: We disagree with the commenters statements that EPA did
not consider and weigh all the available information in an appropriate
weight-of-evidence approach when making our determination for the area.
In our proposal, we proposed to find that the St. Bernard area did not
attain the 2010 one-hour SO2 NAAQS by the October 4, 2018
attainment date. That proposal and our final action are based on our
review and weighing of all of the relevant, available information,
including

monitoring, emissions, modeling, stack testing information, and
compliance data in determining if the area attained or failed to attain
by the October 4, 2018 attainment date.
    As discussed in more detail in preceding responses (Responses in
sections II.A.1 through II.A.4), EPA has evaluated comments and
available information and assessed if overall each comment group
provides relevant information that the area attained or did not attain
the 1-hour SO2 NAAQS by October 4, 2018.
    Comments summarized in subsection II.A.1 relate to decreases in
emissions and modeled emissions in St. Bernard from Rain and other
SO2 sources. See our responses to the comments and
information in subsection II.A.1. Overall EPA found the comments did
not provide sufficient information that clearly shows the area attained
by October 4, 2018, only that emissions have decreased. As explained in
subsection II.A.1, LDEQ's modeling accounted for all emission
reductions at the time the modeling was performed in 2018 by
incorporating the most recent short term allowable emissions for the
modeled sources in St. Bernard Parish.
    Comments summarized in subsection II.A.2 relate to decreases in
monitored values, recent monitored values that are not violating the
standard, and location of modeled maximum values versus values at the
monitor locations. See our responses to the comments and information in
subsection II.A.2. Overall, EPA found the comments did not provide
sufficient information that clearly shows the entire area attained or
did not attain by October 4, 2018, and we conclude commenters did not
provide any substantial evidence that the area did or did not attain,
simply that monitoring levels have dropped. We provide additional
explanation in subsection II.A.2 that the monitors are not located such
that they are representative of the maximum SO2
concentrations in the area and thus do not provide sufficient evidence
that the area has attained.
    Comments summarized in subsection II.A.3 relate to whether the
modeling as conducted is overly conservative and overestimates
concentrations. See our responses to the comments and information in
subsection II.A.3. Overall, EPA found the comments did not provide
sufficient, additional information that clearly shows the area attained
and instead, some of the information provides evidence that non-
compliance periods may have been more numerous than reported, thus
having a higher potential for exceedances in the period of August 2,
2018 through October 4, 2018. Such information substantiates our
findings that the area did not attain by October 4, 2018. We conclude
that consideration of the comments and additional information presents
therein did not provide sufficient evidence that the area attained by
October 4, 2018, but in contrast provides further evidence that due to
identified periods of non-compliance coupled with likely additional
non-compliance periods that were not identified due to underestimation
of emissions and/or uncertainty in estimated flow rates, the necessary
emission limitations and stack parameters in the AOC were not fully
implemented. Because the emissions and stack parameters at times fall
outside the limits and conditions modeled in the approved attainment
demonstration, the LDEQ's attainment modeling, contrary to the
commenter's assertions, is not conservative all the time. Moreover, the
non-compliance periods may have resulted in exceedances and potentially
violations of the one-hour SO2 NAAQS in areas other than the
monitored location and thus, EPA cannot find that the area attained.
    Comments summarized in subsection II.A.4 relate to facility
compliance including periods of non-compliance from August 2, 2018
through October 4, 2018 and from October 5, 2018 through June 30, 2021,
and whether periods of non-compliance could result in exceedances/
violations. See our responses to the comments and information in
subsection II.A.4. Overall, EPA found the comments did not provide
additional information that clearly shows the area attained by the
attainment date, in contrast the information further corroborated that
the pyroscrubber emissions were underestimated and calculations for
stack parameters were also inaccurate and would result in further
underestimating emissions for the period August 2, 2018, through
October 4, 2018, thus providing evidence that Rain may have been not in
compliance for periods in addition to those identified for the 2-month
period in 2018. The additional compliance records, stack test reports,
and the information provided in association with the proposed AOC
changes provide further weight of evidence that the Rain facility has
not been able to comply with emission limits and stack parameters in
the August 2, 2018 AOC and that Rain needs new emission limits, new
pyroscrubber emission equation, new formulas for calculating stack
flows, and new modeling. Overall, we conclude that consideration of the
comments and additional information provided therein did not provide
any substantial weight of evidence that the area did attain by October
4, 2018, but does provide further evidence that the limits in the
attainment demonstration SIP had not been fully implemented and that
periods of non-compliance have occurred prior to the attainment date
and continued to occur in St. Bernard Parish. Based on this additional
information, it is evident that the facility was not in compliance with
AOC limits during the period August 2, 2018, through October 4, 2018.
    We disagree with the commenters' statements that we rejected or
ignored data from the monitors in St. Bernard Parish in our proposed
determination. We also disagree that our proposed determination was
based on conjecture and not rationally connected to any evidence. As
EPA stated in its responses stated earlier in this document, EPA
acknowledges that the area's air quality has improved due to emissions
reductions in the area, and that the monitors reflect this improvement
(see sections II.A.1 and II.A.2). EPA considered the data from the
Chalmette Vista and Meraux monitors along with all other relevant
information in its determination. We discussed the degree of potential
impacts from Rain's noncompliance and how that could affect the design
values and attainment in the St. Bernard area as well as its impact to
the attainment demonstration modeling (see sections II.A.3 and II.A.4).
In addition, we explain that with uncertainty about what the actual
emissions and stack flowrates were during these non-compliance periods,
it is not feasible to try to model the periods of non-compliance. We
continue to affirm that (1) the Rain facility's control measures had
not been fully implemented by the attainment date, (2) because the
limits and stack parameters upon which the attainment modeling relied
on have not been met, the attainment modeling with evident compliance
issues tied to it, cannot be supportive of a finding of attainment, and
(3) monitoring data alone is insufficient to determine the area's
attainment. Therefore, contrary to the commenters' assertion, to
determine the area had attained in the face of evidence that the
requirements of the attainment demonstration SIP had not been met,
would have required conjecture. EPA cannot determine with certainty
that the area attained the NAAQS. This forms our basis for
determination that the St. Bernard area failed to attain the
SO2

NAAQS by the October 4, 2018 attainment date.
    In summary, we did weigh all relevant, available information
initially in our proposal to find the area did not attain by October 4,
2018. We have reviewed all comments and information provided therein
and determined that this information provided further corroborative
evidence that Rain was not able to comply with AOC limits on multiple
occasions during the roughly 2-month period up through October 4, 2018.
The EPA also notes that the company is working with LDEQ to develop new
emission limits, a revised emission formula for pyroscrubber emissions,
new formula for calculating air flows through the stacks, revised stack
parameter limits for some of the operating scenarios, and revised
modeling. However, any such revised AOC is not officially before us for
review or action. Again, the combination of the changes to these above-
referenced items and revisions to the AOC is evidence that Rain cannot
comply with the existing AOC and that the EPA approved SIP for St.
Bernard Parish has not been fully implemented. Under CAA section
179(d)(2), if the EPA determines that an area did not attain the NAAQS
by the applicable deadline, LDEQ has up to 12 months from the date of
the determination to submit a revised SIP for the area demonstrating
attainment. The revised SIP will need to address the current air
quality and SO2 emissions in St. Bernard and include new
modeling and a new attainment demonstration package.

B. Comments on Redesignation of the St. Bernard Area

    Comment: Commenters disagreed with EPA's proposed determination
that the St. Bernard area failed to attain the SO2 NAAQS and
requested EPA redesignate the area to unclassifiable or attainment
using the available information, including monitoring data and modeling
results.
    Response: EPA would like to clarify that in this action, EPA is
only making a determination that the St. Bernard area failed to attain
the SO2 NAAQS by the area's attainment date of October 4,
2018. The EPA designated St. Bernard Parish nonattainment for the 2010
one-hour SO2 NAAQS on August 5, 2013, which became effective
on October 4, 2013; St. Bernard Parish has remained designated
nonattainment since its initial designation and that designation status
will not be affected by this action.
    EPA notes that the CAA section 107(d)(3)(F) explicitly prohibits
redesignating areas from nonattainment to unclassifiable. Furthermore,
this action is not an action that redesignates the St. Bernard area
from nonattainment to attainment in accordance with the requirements
prescribed in CAA section 107(d)(3)(E). We also note that in a May 29,
2019 final action, we approved the St. Bernard area's SO2
nonattainment SIP planning requirements, including the attainment
demonstration (84 FR 24712); however, that action also did not change
the nonattainment designation of St. Bernard Parish.
    Once an area is designated as ``nonattainment'' for a standard,
that area retains that nonattainment designation until it meets the
CAA's redesignation requirements. For an area to be redesignated to
attainment, in addition to a determination that the area attained the
2010 SO2 NAAQS, the air agency must also submit, and receive
full approval of a request that satisfies all of the criteria for
redesignation to attainment, including:
    (1) obtain a determination that the area has attained the NAAQS;
    (2) have a fully approved attainment SIP that meets all of the
applicable requirements;
    (3) demonstrate that the improvement in the area's air quality is
due to permanent and enforceable reductions;
    (4) have a fully approved maintenance plan that provides for
continued attainment; and
    (5) satisfy all of the applicable requirements in CAA section 110
and CAA Subpart D.
    However, the EPA again emphasizes that this action is limited to
the EPA's determination that the St. Bernard Parish Area has failed to
attain the 2010 SO2 NAAQS. Any redesignation request would
have to be developed and submitted by the state to EPA and would be
subject to a separate agency action with opportunity for public
participation.

C. Comments on Air Quality Concerns

    Comment: EPA received a number of comments from community members
and community groups raising general environmental and air quality
concerns within and around the St. Bernard area. Commenters stated
their concerns over air pollution from various sources and how that
pollution would affect or has affected their health. Commenters
expressed air quality concerns due to improper enforcement
historically. Some commenters additionally raised environmental justice
concerns due to the proximity of the industrial facilities and the
effect of their emissions on surrounding communities. Commenters
requested that EPA examine the air quality and emissions in the area
and work with LDEQ to ensure all SIP provisions are compliant with the
CAA and that air quality standards and SIP requirements are implemented
and enforced. Commenters also requested that EPA perform cumulative
impact analyses and health risk assessments for the area.
    Response: EPA appreciates these comments, which raise additional
environmental and public health issues of concern in this region of
Louisiana. We wish to first recognize the importance of the issues
raised in comments and have provided responses to those where possible.
However, many of these comments raised are not directly relevant to the
basis for our final decision in this rulemaking, (in other words, the
issues and points raised in the comments, which if adopted, would have
required us to change our proposed determination of whether ambient
SO2 levels in the St. Bernard Parish area met the NAAQS by
the attainment date.) It is important to note that only comments
addressing whether SO2 levels in the area met the
SO2 air quality standard can be considered as a part of our
decision-making process for this final action.
    As a general matter, we wish to recognize commenters' concerns that
certain communities are disproportionately impacted by environmental
harms and risks. Nationwide, EPA is working to address disproportionate
impacts in many aspects of our programs to the greatest extent allowed
by federal law. While we did not base our final finding of the failure
to attain on specific environmental justice factors, we do wish to
share for informational purposes only that this final rule is not
anticipated to have disproportionately high or adverse human health or
environmental effects on communities with environmental justice
concerns because it is not anticipated to result in or contribute to
emissions increases in St. Bernard Parish, Louisiana. CAA section
179(d) requires that the State must conduct additional air quality
analysis and evaluation of further SO2 reductions in the
area to provide for attainment of the NAAQS and must submit to EPA a
new SIP for this purpose within one year of the publication of this
final action.
    With regards to concerns about LDEQ's surveillance and enforcement
program in the region, EPA is committed to our mission to protect human
health and the environment by ensuring that federal laws protecting
human health and the environment are administered and enforced fairly,
effectively, and as Congress intended, including through EPA's
oversight role

in the implementation of the CAA. EPA works closely with LDEQ to ensure
that LDEQ is properly implementing its program. We accomplish this
through close coordination on specific investigations and enforcement
actions, monthly calls, and regular program reviews through the State
Review Framework.\33\ Additionally, EPA maintains authority to conduct
inspections and initiate enforcement actions within the state of
Louisiana. In April 2021, EPA's Office of Enforcement and Compliance
Assurance issued a memo entitled, ``Strengthening Enforcement in
Communities with Environmental Justice Concerns,'' which directs the
EPA Regional Offices to increase our facility inspections in
overburdened communities. Since the memo was issued, EPA Region 6 has
increased our air inspections in Louisiana's overburdened communities
and those areas with environmental justice concerns.
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    \33\ See https://www.epa.gov/compliance/state-review-framework.
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    In addition, EPA announced several key actions on January 26, 2022,
aimed at finding solutions to the environmental burdens that EPA
Administrator Michael S. Regan encountered on his November 2021 Journey
to Justice Tour through Mississippi, Louisiana, and Texas. The Tour
spotlighted longstanding environmental justice concerns in historically
marginalized communities and allowed Administrator Regan to hear
firsthand from residents dealing with the impacts of pollution.
Specifically, EPA committed to address environmental justice concerns
by conducting a Multi-Scale Monitoring Project. This project includes
unannounced inspections, sampling, and air monitoring in priority
areas. More about the Multi-Scale Monitoring Project can be found at
https://www.epa.gov/newsreleases/epa-administrator-regan-announces-bold-actions-protect-communities-following-journey.
    Commenters requested that EPA should perform cumulative impact
analyses and health risk assessments for the area and region. EPA is
working to develop tools, metrics, and guidance to assess cumulative
impacts and human health risk assessments and incorporate these into
our programs. As provided in the EPA's FY 2022-FY 2026 Strategic
Plan,\34\ one of the Fiscal Year 2022-2023 Agency Priority Goals
includes delivering ``tools and metrics for EPA and its Tribal, state,
local, and community partners to advance environmental justice and
external civil rights compliance.'' Specifically, by September 30,
2023, EPA will ``develop and implement a cumulative impacts framework,
issue guidance on external civil rights compliance, establish a set of
at least 10 indicators to assess EPA's performance in reducing
disparities in environmental and public health conditions, and train
staff and partners on how to use these resources.''
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    \34\ See https://www.epa.gov/planandbudget/strategicplan.
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    We encourage citizens and communities to continue to engage with
EPA and LDEQ to raise specific concerns regarding permitting and
enforcement actions within the Parish.
    Comment: A number of commenters specifically mentioned the proposed
mega international port, terminal, and container yard in Violet, St.
Bernard Parish LA (Port of New Orleans's Louisiana International
Terminal) and asked that this project not be built, citing concerns
that it would deteriorate the air quality in St. Bernard Parish and
cause harm to its residents.
    Response: We note that this comment is outside the scope of this
rulemaking and involves separate regulatory actions, but in an effort
to aid and inform the public and identify opportunities for public
comment on the proposed project, the following response is provided.
    The Port of New Orleans (PONO) is seeking permits from the U.S.
Army Corps of Engineers (USACE) to build its proposed terminal project
in Violet, St. Bernard Parish, Louisiana. In response to PONO's permit
application, USACE deemed the application complete and issued a public
notice on January 24, 2022, and again on March 28, 2022, under USACE
reference permit number MVN-2021-00270-EG requesting comments from
interested parties on the application to consider and evaluate the
impacts of the proposed activity. USACE is currently reviewing comments
received during the public comment period to determine the next steps
on the permits for the project, prepare an environmental analysis
pursuant to the National Environmental Policy Act of 1969 (NEPA), and
determine public interest in the project.
    Under NEPA, USACE, as the lead federal agency, must study the
potential impacts of the LIT project on the physical, cultural, human,
and natural environments before permitting construction. The study must
also identify actions to minimize negative impacts and evaluate
alternatives to the proposed project that could serve the same purpose.
    USACE will ask the public what potential impacts should be studied
through a public process of scoping meetings and comment periods
tentatively scheduled to begin in October 2022. The resulting NEPA
environmental analysis prepared by USACE will be public noticed for
review and comment by any interested parties. The EPA NEPA program
plans to participate in the scoping and public comment phases of
USACE's NEPA environmental analysis. The USACE public notices for the
PONO's terminal project will be available at https://www.mvn.usace.army.mil/Missions/Regulatory/Public-Notices/.
    Comment: The commenters stated that LDEQ should be required to
submit a revised SIP to EPA, provide expeditious attainment of the
SO2 NAAQS, and provide for additional measures to protect
public health. The commenters also stated that EPA should consider
updated air dispersion modeling for all sources in the St. Bernard
Parish.
    Response: We appreciate and acknowledge the commenter's statements.
In this action, EPA is finalizing our finding that the St. Bernard
Parish SO2 nonattainment area failed to attain the 2010
SO2 standard by the attainment date of October 4, 2018. This
action triggers under CAA section 179(d) a requirement from the State
of Louisiana to submit, within one year of its publication, revisions
to the Louisiana SIP that, among other elements, provide for
expeditious attainment of the 2010 SO2 standard. This
revised SIP to meet nonattainment area requirements to provide for
attainment is typically called an attainment demonstration SIP or
attainment SIP or plan.
    We agree with the commenters that it is important to consider all
emission sources of SO2 in developing a plan that is
protective of the NAAQS and note that this type of analysis is a
necessary component of the attainment SIP for the area. The required
revised SO2 attainment plan must address two main
components: (1) Emission limits and other control measures that assure
implementation of permanent, enforceable, and necessary emission
controls, and (2) a modeling analysis which demonstrates that these
emission limits and control measures provide for timely attainment of
the NAAQS. The required modeling includes modeling the cumulative
impact of all SO2 emission sources in the area on ambient
air quality and must demonstrate that the entire nonattainment area
(all of St. Bernard Parish) will attain the standard with the
implementation of the necessary emission limits. The modeling
demonstration in the 2018

attainment SIP analyzed emissions from the three major SO2
sources in the parish (Valero Refining, Chalmette Refining, and Rain,
which contributed 99% of the point source emissions in the area) using
maximum allowable emissions and federally enforceable permit
limits.\35\ The revised SIP must include an updated modeling
demonstration reflecting the current permitted and other federally
enforceable allowable emissions for sources in the area. In addition,
the attainment SIP requirements include a requirement for an emission
inventory of current emissions for all sources of SO2 in the
nonattainment area. That information would enable the EPA to identify
any new large sources of SO2 when determining which sources
should be modeled and addressed in a new attainment demonstration SIP.
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    \35\ See Section IV.C. of the April 19, 2018 proposal,
``Approval and Promulgation of Implementation Plans; Louisiana;
Attainment Demonstration for the St. Bernard Parish 2010
SO2 Primary National Ambient Air Quality Standard
Nonattainment Area'' (83 FR 17349).
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D. Comments on State Programs

    Comment: The commenter requested that EPA withdraw its approval of
the State of Louisiana's authority to implement the CAA within St.
Bernard Parish and that, instead, EPA Region 6 assume the authority and
responsibility for designing, approving, implementing, and enforcing
air quality implementation plans for St. Bernard Parish.
    Response: We note that this comment is outside the scope of this
rulemaking, but to better aid and inform the public, the following
response is provided on the topic of state delegated authorities under
the CAA.
    States, local governments, territories, and tribes are not provided
a blanket approval of authorities to implement the federal Clean Air
Act within their respective jurisdictions. Air quality programs and
plans are individually submitted to the EPA for review and approval,
and if the programs and plans meet CAA requirements, then EPA is
obligated to approve them. We note that the CAA requires EPA to approve
any and all SIPs that satisfy the applicable CAA requirements. The CAA
prescribes a regulatory scheme that envisions a collaborative process
between the states and federal government. The EPA reviews and approves
state-wide regulatory programs for each state, such as the new source
review (NSR) and Title V permitting program, as well as NAAQS-specific
infrastructure SIPs; EPA also reviews and approves area-specific plans
within the state to implement and enforce control measures providing
for attainment of the NAAQS. EPA's review of such programs and plans
ensures that implementation mechanisms and enforcement authority are
adequate to meet CAA requirements, but actual enforcement is generally
undertaken by states with EPA and citizens also having enforcement
authority.
    Comment: Commenters made recommendations for LDEQ's permitting
process. Commenters recommended that an oversight board be established
for the LDEQ, that a conflict of interest policy be established for
LDEQ staff members that issue permits, and that the LDEQ be required to
establish a written policy that guides when public hearings are
required. Commenter stated that EPA should consider delaying the
issuance of all Title V permits until health risks and cumulative
impacts are reviewed and improvements incorporated in Title V permits.
    Response: We note that this comment is outside the scope of this
rulemaking, but to better aid and inform the public, the following
response is provided on the topic of state permitting programs.
    EPA ensures that mechanisms are in place and that a state has
adopted the appropriate statutory and regulatory authority. For
example, the State has included the required opportunities for public
participation (as approved in the State's Title V program), but more
specific decisions such as written guidance dictating when public
hearings are required is left to the State's expertise.
    As required under Title V of the CAA, EPA has promulgated rules
which define the minimum elements of an approvable State operating
permits program and the corresponding standards and procedures by which
EPA will approve, oversee, and withdraw approval of a State operating
permits program (57 FR 32250, July 21, 1992). These rules are codified
at 40 CFR part 70. Title V requires states to develop and submit to EPA
programs for issuing these operating permits to all major stationary
sources and to certain other sources. EPA's Operating Permits Program
review occurs pursuant to section 502 of the CAA and the part 70
regulations, which together outline criteria for approval and
disapproval. Title V operating permits must address applicable federal
CAA requirements, including requirements for public participation (see
40 CFR 70.7(h)). EPA promulgated final full approval of the State of
Louisiana's Title V Operating Permits Program on September 12, 1995 (60
FR 47296).
    On December 28, 2016, EPA approved revisions to the Louisiana SIP
that addressed requirements in CAA section 128 regarding state board
composition and conflict of interest and disclosure requirements (81 FR
95477). LDEQ is an executive agency that acts through its Secretary and
approves all CAA permits and enforcement orders in Louisiana. LDEQ
stated in its submittal that for public disclosure of any potential
conflict in the SIP, as required by CAA section 128, that if a person
derives anything of economic value that such person should be aware,
he/she must disclose specified elements under the Louisiana Revised
Statutes (LA RS) Title 42; Chapter 15: Code of Governmental Ethics;
Section 1114(A)(1)-(4) and (C) ``Financial disclosure.'' These relevant
revised statutes approved into the SIP demonstrates that Louisiana
complies with the requirements of CAA section 128.
    Comment: Commenters stated that LDEQ's permitting program
prioritizes facility permit approvals without consideration of public
comments and limits public participation. Commenters cited the approval
of the PBF Chalmette Refinery, LLC's application for a Part 70 permit
to construct and operate a Renewable Diesel Unit and the associated
variance application as a recent example of the commenters' claimed
permitting program inadequacies. Commenters recommended auditing LDEQ's
public participation process for its permitting program by identifying
projects that have received more than a specified number of comments,
and if any resulted in a change of the project description.
    Response: We note that this comment is outside the scope of this
rulemaking, but to better aid and inform the public, the following
response is provided.
    EPA notes that in the LDEQ's permit application process for the
Chalmette Renewable Diesel Unit issued on December 21, 2021, LDEQ found
that the application satisfied the permit application requirements. As
provided earlier in this notice, LDEQ's permitting program satisfies
the CAA requirements and has received EPA's approval. We additionally
note that LDEQ stated in its final approval that it amended the permit
as a result of public comments. As a result of the public participation
process that citizens engaged in with the LDEQ, the permit was amended
as follows: N-hexane emissions from the hotwells were required to be
controlled to 98 percent rather than 95 percent and limited to 17.90
tons per year (tpy); Particulate Matter emissions from the cooling
tower are now controlled to

0.005 percent rather than 0.02 percent with resulting annual emissions
limits of 4.47 tpy PM2.5 and 4.05 tpy PM10. In
addition, the control efficiency on the vacuum systems and dust
collectors which control emissions from bleached earth loading and
filter aid loading will be increased from 95 to 99 percent. The process
heaters will be fired exclusively with natural gas rather than refinery
gas, resulting in lower SO2 emissions due to the lower
sulfur content of the fuel. Heater 23a will be fitted with low nitrous
oxide (NOX) burners and constrain its firing rate to 55
MMBTU/hr, thus reducing NOX emissions and all other products
of incomplete combustion. Taken together, these permit changes will
result in lower emissions.
    EPA also notes that it is within LDEQ's authority to issue
variances. The Louisiana regulations generally prohibit commencement of
construction unless a permit is issued, and fees paid (LAC
33:III.501(C)(2) and (3)). However, the variance provisions, approved
as part of Louisiana's Title V Operating Permits Program on September
12, 1995 (60 FR 47296) and incorporated at LAC 33:III.525, provide that
minor permit modifications or variances under a Title V permit program
are not required to undergo public participation requirements (see 40
CFR 70.7(e)(2) and (3), and 40 CFR 70.4(d)(3)(iv)).
    EPA notes that for the permit application process for the Chalmette
Renewable Diesel Unit issued on December 21, 2021, LDEQ responded to
over 100 distinct comments, and as a result of citizen engagement in
the public participation process, the permit was amended, and the
resulting changes are anticipated to lower emissions at the site as
described earlier in this notice.
    In general, a Title V petition allows anyone to raise concerns to
EPA and to ask the Agency to object to the issuance of a new, modified,
or renewed operating permit for a specific facility if the concerns
with the permit were raised to the permitting authority during the
notice and comment period for the permit action. If a member of the
public believes that a Title V permit issued by a state, local, or
tribal permitting authority does not comply with the CAA or the EPA's
Title V permit implementing regulations (40 CFR part 70), they may
petition EPA to object to the permit pursuant to certain Title V
petition requirements. If EPA grants a petition and objects to the
issuance of a permit, the permitting authority must correct or rectify
issues with the permit. EPA has 45 days to review a Title V permit
proposed by a permitting authority. If the Administrator does not
object to a permit during that time, the public has 60 days to petition
the Administrator to object to the permit.
    For more information on the Title V program, opportunity to
petition a state-issued Title V permit, and EPA's authority and
oversight role on a state's EPA-approved Title V permit program, visit
https://www.epa.gov/title-v-operating-permits.
    Comment: Commenters requested EPA to allow the use of low-cost,
reliable sensors as part of the Louisiana Annual Monitoring Network
Plan and install additional monitors in the area in order to better
inform the public about the air quality in the area and to protect the
health and well-being of those impacted by pollution. Commenters stated
that the current State of Louisiana monitoring network is inadequate.
    Response: We note that this comment is outside the scope of this
rulemaking, but to better aid and inform the public, the following
response is provided.
    EPA acknowledges that an increasing number of low-cost air quality
sensors are now available on the commercial market, but the amount of
research-based evaluation of these sensors remains very limited. EPA is
engaged in the discovery, evaluation, and application of these emerging
technologies and is sharing information gained with its partners and
stakeholders. EPA scientists are involved in the evaluation of some air
sensors for use by the public and provide the information in reports,
but do not make any endorsements or recommendations for their use. Data