[Federal Register Volume 84, Number 29 (Tuesday, February 12, 2019)]
[Proposed Rules]
[Pages 3389-3395]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-01908]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R08-OAR-2018-0723; FRL-9988-63--Region 8]
Approval and Promulgation of Air Quality Implementation Plans;
Wyoming; Interstate Transport for the 2008 Ozone National Ambient Air
Quality Standards
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA) is proposing action
on a submission from the State of Wyoming that is intended to
demonstrate that the Wyoming State Implementation Plan (SIP) meets
certain interstate transport requirements of the Clean Air Act (Act or
CAA) for the 2008 ozone National Ambient Air Quality Standards (NAAQS).
This submission addresses interstate transport ``prong 2,'' which
requires each state's SIP to prohibit emissions which will interfere
with maintenance of the NAAQS in other states. The EPA is proposing to
approve this submittal as meeting the requirement that Wyoming's SIP
contain adequate provisions to prohibit emissions in amounts which will
interfere with maintenance of the 2008 ozone NAAQS in any other state.
DATES: Written comments must be received on or before March 14, 2019.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2018-0723, to the Federal Rulemaking Portal: https://www.regulations.gov. Follow the online instructions for submitting
comments. Once submitted, comments cannot be edited or removed from
www.regulations.gov. The EPA may publish any comment received to its
public docket. Do not submit electronically any information you
consider to be Confidential Business Information (CBI) or other
information whose disclosure is restricted by statute. Multimedia
submissions (audio, video, etc.) must be accompanied by a written
comment. The written comment is considered the official comment and
should include discussion of all points you wish to make. The EPA will
generally not consider comments or comment contents located outside of
the primary submission (i.e., on the web, cloud, or other file sharing
system). For additional submission methods, the full EPA public comment
policy, information about CBI or multimedia submissions, and general
guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
Docket: All documents in the docket are listed in the
www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in www.regulations.gov or in hard copy at the Air Program,
Environmental Protection Agency (EPA), Region 8, 1595 Wynkoop Street,
Denver, Colorado 80202-1129. The EPA requests that if at all possible,
you contact the individual listed in the FOR FURTHER INFORMATION
CONTACT section to view the hard copy of the docket. You may view the
hard copy of the docket Monday through Friday, 8:00 a.m. to 4:00 p.m.,
excluding federal holidays.
FOR FURTHER INFORMATION CONTACT: Adam Clark, Air Program, EPA, Region
8, Mailcode 8P-AR, 1595 Wynkoop Street, Denver, Colorado 80202-1129,
(303) 312-7104, [email protected].
SUPPLEMENTARY INFORMATION: Throughout this document wherever ``we,''
``us'' or ``our'' is used, we mean the EPA.
I. Background
On March 12, 2008, the EPA revised the levels of the primary and
secondary 8-hour ozone NAAQS to 0.075 parts per million (ppm). 73 FR
16436 (Mar. 27, 2008). The 2008 ozone NAAQS are met at an ambient air
quality monitoring site when the 3-year average of the annual fourth-
highest daily maximum 8-hour average ozone concentration is less than
or equal to the NAAQS, as determined in accordance with Appendix P to
40 CFR part 50. Under Appendix P, digits to the right of the third
decimal place are truncated.
Section 110(a)(1) of the CAA requires states to submit, within 3
years after promulgation of a new or revised NAAQS, SIPs meeting the
applicable ``infrastructure'' elements of sections 110(a)(1) and (2).
One of these applicable infrastructure elements, CAA section
110(a)(2)(D)(i), requires SIPs to address the ``good neighbor''
provision which requires states to prohibit certain adverse air quality
effects on other states due to interstate transport of pollution.
A. The EPA's Interpretation and Implementation of the Good Neighbor
Provision
Specifically, section 110(a)(2)(D)(i)(I) requires SIPs to contain
adequate provisions prohibiting any source or other type of emissions
activity in one state from emitting any air pollutant in amounts that
will contribute significantly to nonattainment, or interfere with
maintenance, of the NAAQS in any other state. The two provisions of
this section are referred to as prong 1 (significant contribution to
nonattainment) and prong 2 (interfere with maintenance). Section
110(a)(2)(D)(i)(II) requires SIPs to contain adequate provisions to
prohibit emissions that will interfere with measures required to be
included in the applicable implementation plan for any other state
under part C to prevent significant deterioration of air quality (prong
3) or to protect visibility (prong 4).
The EPA has established a four-step interstate transport framework
to address the prong 1 and 2 requirements for ozone and fine
particulate matter (PM2.5) NAAQS through the development and
implementation of several previous rulemakings.\1\ The four steps of
this framework are as follows: (1) Identify downwind air quality
problems; (2) identify upwind states that impact those downwind air
quality problems enough to warrant further review and analysis; (3)
identify the emissions reductions, if any, necessary to prevent an
identified upwind state
[[Page 3390]]
from contributing significantly or interfering with maintenance with
respect to those downwind air quality problems; and (4) adopt permanent
and enforceable measures needed to achieve those emissions reductions.
The EPA has applied this framework in various actions addressing prongs
1 and 2 for the PM2.5 and ozone NAAQS.\2\
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\1\ See, e.g., Finding of Significant Contribution and
Rulemaking for Certain States in the Ozone Transport Assessment
Group Region for Purposes of Reducing Regional Transport of Ozone
(also known as the NOx SIP Call). 63 FR 57356 (October 27, 1998);
Clean Air Interstate Rule (CAIR) Final Rule. 70 FR 25162 (May 12,
2005); Cross-State Air Pollution Rule (CSAPR) Final Rule. 76 FR
48208 (August 8, 2011); CSAPR Update. 81 FR 74504 (October 26,
2016).
\2\ See, e.g., ``Interstate Transport Prongs 1 and 2 for the
2012 Fine Particulate Matter (PM2.5) Standard for
Colorado, Montana, North Dakota, South Dakota and Wyoming,'' 83 FR
21227 (May 9, 2018); ``Approval and Promulgation of Air Quality
State Implementation Plans; California; Interstate Transport
Requirements for Ozone, Fine Particulate Matter, and Sulfur
Dioxide,'' 83 FR 5375 (February 7, 2018).
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On August 4, 2015, the EPA issued a Notice of Data Availability
(NODA) containing air quality modeling to assist states with meeting
section 110(a)(2)(D)(i)(I) requirements for the 2008 ozone NAAQS within
the context of the four-step framework.\3\ Specifically, the air
quality modeling helped states address steps 1 and 2 of the framework
by (1) identifying locations in the United States where the EPA
anticipated nonattainment or maintenance issues in 2017 for the 2008
ozone NAAQS, and (2) quantifying the projected contributions from
emissions from upwind states to downwind ozone concentrations at the
receptors in 2017. The EPA also used this modeling to support the
Cross-State Air Pollution Rule Update for the 2008 Ozone NAAQS (``CSAPR
Update'') proposed rule (80 FR 75706, December 3, 2015); we updated the
modeling in 2016 to support the CSAPR Update final rule (81 FR 74504,
October 26, 2016). The projections in this updated version of the
modeling (hereon referred to as the ``CSAPR Update modeling'') were
part of the technical record for the EPA's February 3, 2017 final
action on the prongs 1 and 2 portions of the Wyoming 2008 Ozone
Infrastructure SIP, which is discussed in more detail later in this
notice. 82 FR 9153.
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\3\ See Notice of Availability of the Environmental Protection
Agency's Updated Ozone Transport Modeling Data for the 2008 Ozone
National Ambient Air Quality Standard (NAAQS), 80 FR 46271 (August
4, 2015); see also ``Updated Air Quality Modeling Technical Support
Document for the 2008 Ozone NAAQS Transport Assessment,'' August
2015 (included in the docket to the NODA).
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In the CSAPR Update, the EPA used the CSAPR Update modeling to
identify downwind nonattainment and maintenance receptors at step 1 of
the four-step framework (see 81 FR 74530-74532, October 26, 2016).
Specifically, the EPA identified nonattainment receptors as those
monitoring sites with current measured design values exceeding the
NAAQS that also have projected (i.e., in 2023) average design values
exceeding the NAAQS. The EPA identified maintenance receptors as those
monitoring sites with projected maximum design values exceeding the
NAAQS. The EPA considered all nonattainment receptors to also be
maintenance receptors because a monitoring site with a projected
average design value above the standard necessarily also has a
projected maximum design value above the standard. Monitoring sites
with projected maximum design values that exceed the standard and which
are not also nonattainment receptors are thus referred to as
maintenance-only receptors.
To address step 2 of the framework for the CSAPR Update, the EPA
used the CSAPR Update modeling to determine whether an eastern state's
impact on each projected downwind air quality problem would be at or
above a specific threshold. The EPA's modeling projected ozone
concentrations and contributions in 2017, which would be the last ozone
season before the then-upcoming July 2018 attainment date for
nonattainment areas classified as Moderate for the 2008 ozone NAAQS.
Consistent with the original CSAPR rulemaking (76 FR 48208, August 8,
2011), the EPA applied a threshold of one percent of the 2008 ozone
NAAQS of 75 ppb (0.75 ppb) to identify linkages between upwind states
and downwind nonattainment and maintenance receptors in the CSAPR
Update. 81 FR 74518 (October 26, 2016). If a state's impact on
identified downwind nonattainment and maintenance receptors did not
exceed 0.75 ppb, the state was not considered ``linked'' to those
receptors and was therefore not considered to significantly contribute
to nonattainment or interfere with maintenance of the standard in those
downwind areas. If a state's impact exceeded the 0.75 ppb threshold,
that state was considered ``linked'' to the downwind nonattainment or
maintenance receptor(s) and the state's emissions were evaluated
further, taking into account both air quality and cost considerations,
to determine what, if any, emissions reductions might be necessary to
address the state's obligation pursuant to CAA section
110(a)(2)(D)(i)(I).
B. Wyoming's Submittals To Address the Good Neighbor Provisions
On February 6, 2014, the Wyoming Department of Environmental
Quality (WDEQ) submitted a certification that the approved Wyoming SIP
adequately addressed the ``good neighbor'' provision for the 2008 ozone
NAAQS. See 81 FR 71712, 71713 (Nov. 18, 2016). On November 18, 2016,
the EPA proposed to approve Wyoming's submission for prong 1 and
disapprove Wyoming's submission for prong 2 of the good neighbor
provision (81 FR 81712), and on February 3, 2017, the EPA finalized the
proposed approval and disapproval. 82 FR 9153. This disapproval
established a 2-year deadline, under CAA section 110(c), for the EPA to
promulgate a federal implementation plan (FIP) or approve a SIP that
meets the requirements of prong 2 of the good neighbor provision for
the 2008 ozone NAAQS for Wyoming. The EPA acted on the portions of the
submission addressing prongs 1, 3 and 4 of the good neighbor provision
for the 2008 ozone NAAQS.\4\
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\4\ See 81 FR 70362 (Oct. 12, 2016) for prong 3 final action,
and 82 FR 9142 (February 3, 2017) for prongs 1 and 4 final action.
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The EPA based its February 3, 2017 disapproval for prong 2 in the
first instance on a determination that the February 6, 2014 submission
lacked an analysis to support the conclusion that the Wyoming SIP
contained adequate provisions prohibiting emissions that will interfere
with maintenance of the 2008 ozone NAAQS in any other state. 81 FR
81714 (proposal); 82 FR 9147 (final). As explained in the notices for
the proposed and final action, in accordance with the decision of the
United States Court of Appeals for the District of Columbia Circuit
(D.C. Circuit) in North Carolina v. EPA, 531 F.3d 896, 910-11 (2008),
states and the EPA are required to give ``independent significance'' to
prong 2 by considering the potential impacts of emissions on areas that
may have issues maintaining the standards. 82 FR 9145.
However, if the EPA's supplemental analysis supports the state's
conclusion that the SIP is adequate to address the statutory
requirements, we may approve the state's submittal. 82 FR 9149. In this
case, the EPA evaluated the CSAPR Update modeling, described above.
That modeling showed that emissions from Wyoming were not linked to any
nonattainment receptors for the 2008 ozone NAAQS in the 2017 analytic
year. However, the modeling also showed that emissions from Wyoming
were projected to contribute above the 1% threshold to one maintenance
receptor at the Chatfield Reservoir in Douglas County, Colorado
(monitor I.D. # 80350004).\5\ The CSAPR Update
[[Page 3391]]
modeling identified two other maintenance receptors in the Denver
Metro/North Front Range (DMNFR) 2008 Ozone Moderate nonattainment area,
but emissions from Wyoming were projected to impact those receptors
below the 0.75 ppb threshold. For the purpose of our action on the
Wyoming SIP submission, we determined that a 1% screening threshold was
appropriate to use for the Douglas County maintenance receptor because
the air quality problem in that area resulted in part from the
relatively small individual contributions of upwind states that
collectively contribute a large portion of the ozone concentrations
(9.7%), comparable to some eastern receptors addressed in the CSAPR
Update. 82 FR 9149-50. The CSAPR Update modeling projected that Wyoming
emissions would contribute 1.18 ppb, or approximately 1.57% of the 2008
ozone NAAQS, at the Douglas County maintenance receptor in 2017.\6\ As
this contribution was above the screening threshold, we could not
conclude on the basis of the CSAPR Update modeling that Wyoming's SIP
contained sufficient provisions to prohibit emissions that will
interfere with maintenance of the 2008 ozone NAAQS at the Douglas
County maintenance receptor. As a result, the EPA disapproved the
February 6, 2014 submittal for prong 2.
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\5\ The Douglas County maintenance receptor is located in the
2008 ozone Denver Metro/North Front Range (DMNFR) Moderate
nonattainment area. See https://www3.epa.gov/airquality/greenbook/hnp.html#Ozone_8-hr.2008.Denver. However, the EPA has routinely
interpreted the section 110(a)(2)(D)(i)(I) requirements to be
independent of formal designations because any area may be in
nonattainment or struggle to maintain the NAAQS, regardless of
formal area designation.
\6\ The updated modeling data (published on EPA's website at
https://www.epa.gov/airmarkets/final-cross-state-air-pollution-rule-update on September 7, 2016) are available in the docket for this
action.
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II. State Submittal
WDEQ submitted a new interstate transport SIP on October 17, 2018,
providing additional information to demonstrate that the State meets
the prong 2 requirement for the 2008 ozone NAAQS. In this submittal,
WDEQ addressed the prong 2 requirements of section 110(a)(2)(D)(i)(I)
using a weight of evidence analysis and concluded that emissions from
Wyoming will not interfere with maintenance of the 2008 ozone NAAQS in
any other state. The submittal states that weight of evidence analyses
are a valid approach to assessing ozone transport in western states and
have been used by the EPA and in submittals by other western states,
specifically California. Consistent with the CSAPR Update modeling,
which only found one potential linkage with the Douglas County
maintenance receptor, WDEQ focused its analysis on the potential
impacts of Wyoming emissions on that receptor. WDEQ's analysis included
information about recent and forthcoming emission reductions at sources
in Wyoming; ozone modeling for the 2023 analytic year from the EPA's
October 27, 2017 memorandum ``Supplemental Information on the
Interstate Transport State Implementation Plan Submissions for the 2008
Ozone National Ambient Air Quality Standards under Clean Air Act
Section 110(a)(2)(D)(i)(I)'' (hereon ``October 2017 Memo''); and the
EPA's proposed approval (since finalized) of the ``Colorado Attainment
Demonstration for the 2008 8-Hour Ozone Standard for the DMNFR Moderate
nonattainment area'' (hereon ``DMNFR attainment demonstration''). 83 FR
14807 (April 6, 2018).
WDEQ indicated that the Douglas County monitor was projected to be
a maintenance receptor for the year 2017 in the CSAPR Update modeling.
However, WDEQ stated that it is unclear whether it should still
consider the Douglas County monitor to be maintenance for this NAAQS,
given its review of information available subsequent to the CSAPR
Update modeling. Specifically, WDEQ cited the EPA's October 2017 Memo
and the State of Colorado's attainment demonstration for the 2008 8-
Hour Ozone Standard for the DMNFR nonattainment area to argue that the
Douglas County receptor should not be considered a maintenance receptor
for the 2008 ozone NAAQS.
First, WDEQ referenced the EPA's October 2017 Memo. As described in
further detail in Section III of this notice, the EPA performed air
quality modeling, released in the October 2017 Memo, to project 2008
ozone nonattainment and maintenance receptors for the analytic year
2023 to assist the states in addressing remaining prong 1 or prong 2
obligations for the 2008 ozone NAAQS. This modeling projected a maximum
design value of 73.2 ppb (below the 75 ppb NAAQS) for the Douglas
County receptor in the 2023 analytic year. October 2017 Memo at A-7.
WDEQ also cited language from the October 2017 Memo which states that
``no areas in the United States, outside of California, are expected to
have problems attaining and maintaining the 2008 ozone NAAQS in 2023.''
Id. at 4.
WDEQ then referenced modeling performed by the State of Colorado as
part of its DMNFR attainment demonstration.\7\ Specifically, WDEQ
referenced modeling from Colorado's weight of evidence attainment
demonstration in which Colorado removed monitoring data for certain
days during 2010-2013 from the calculation of the 2011 baseline ozone
design value because these data were likely influenced by atypical
events such as stratospheric intrusions or wildfires. Colorado's
modeling, which will be discussed in further detail in Section III of
this notice, projected the Douglas County monitor would have a maximum
modeled design value below the 2008 NAAQS in 2017 when the adjusted
2011 baseline was used. 83 FR 14813 (April 6, 2018). As noted by WDEQ,
in the EPA's proposed approval of Colorado's DMNFR attainment
demonstration, we concurred with Colorado's assessment that this
modeling was properly configured, met EPA performance requirements, and
was appropriately used in its application. Id. The EPA has since
finalized our proposed approval of Colorado's DMNFR attainment
demonstration. 83 FR 31068 (July 3, 2018).
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\7\ The Colorado 2008 Ozone Moderate Nonattainment Area SIP
Submission is available on regulations.gov as document ID # EPA-R08-
OAR-2017-0567-0004.
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In its October 17, 2018 submission, WDEQ asserted that the modeling
from both the EPA's October 2017 Memo and Colorado's DMNFR attainment
demonstration indicate that all future design values for the Douglas
County receptor are below the 2008 ozone NAAQS. Therefore, WDEQ asserts
that this receptor should no longer be considered a maintenance
receptor, as it was identified in the CSAPR Update modeling, but should
instead be considered to be attainment.
WDEQ also included information about recent and forthcoming
emission reductions at sources in Wyoming in its weight-of-evidence
analysis. Specifically, WDEQ provided information about nitrogen oxide
(NOX) and volatile organic compounds (VOC) emissions
reductions that occurred between 2011 and 2017, and NOX
reductions that will occur before 2023. WDEQ focused on these
pollutants as both are precursors to ozone. WDEQ calculated that
permitting actions, including Title V permit rescissions for sources
that have reduced their emissions from major to minor source levels,
accounted for a statewide reduction of 12,392.5 tons per year (tpy) of
NOX and 905.6 tpy of VOC between 2011 and 2017. WDEQ noted
that regulations covering nonpoint sources and reductions from leak
detection and repair or fugitive emissions monitoring programs had led
to additional VOC reductions, though WDEQ had not quantified the
reductions from these regulations. WDEQ also calculated a 21,525 tpy
NOX reduction between 2017
[[Page 3392]]
and 2023, concluding NOX emissions would decrease by nearly
18% from those reported in the 2011 Emission Inventory (the inventory
used in the CSAPR Update modeling and October 2017 Memo modeling) by
2023 through permitting actions alone. WDEQ also asserted that the
emissions reductions listed in its submission do not appear to have
been accounted for in the CSAPR Update modeling.
WDEQ concludes that all elements of its weight-of-evidence analysis
combined demonstrate that emissions from the State of Wyoming will not
interfere with maintenance of the 2008 8-hour ozone NAAQS in any other
state, including at the Douglas County, Colorado receptor.
III. EPA's Evaluation
The EPA has reviewed all elements of WDEQ's weight-of-evidence
analysis and additional relevant technical information to determine
whether the SIP has adequate provisions to ensure emissions from the
state will not interfere with maintenance of the 2008 ozone NAAQS in
any other state. The EPA conducted this review within the four-step
interstate transport framework. Therefore, the EPA's first step in
reviewing WDEQ's submission is to identify downwind air quality
problems.
A. Identification of Downwind Air Quality Problems
The EPA first reviewed WDEQ's information about modeling conducted
by the State of Colorado that projected attainment of the 2008 ozone
NAAQS at the Douglas County receptor and all other ozone monitors in
the DMNFR Moderate ozone nonattainment area in 2017. Based on
Colorado's DMNFR attainment demonstration modeling results, WDEQ
asserts that the Douglas County receptor should not be considered a
maintenance receptor at step 1 of the four-step interstate transport
framework. As noted, the Douglas County receptor was the only
maintenance receptor to which emissions from Wyoming contributed above
1% of the 2008 ozone NAAQS in the EPA's 2016 CSAPR Update modeling.
The EPA's review of Colorado's DMNFR attainment demonstration
modeling, provided below, begins with an overview of the modeling
analysis in the attainment planning context for which it was originally
generated. Then, we expand on Wyoming's analysis by considering
Colorado's modeling in the context of interstate transport.
Specifically, we consider how Colorado's removal of atypical event-
influenced monitor data in 2010, 2011 and 2012 from the 2011 baseline
ozone design value would impact the CSAPR Update modeling results with
regard to the Colorado receptor to which Wyoming was linked.
In Colorado's primary modeling for the DMNFR attainment
demonstration, the State calculated relative response factors (RRFs)
using the maximum modeled ozone in a 3x3 matrix of grid cells around
each ozone receptor to model a 2017 projected concentration of 76.2 ppb
at the Douglas County receptor. See 83 FR 14811 (April 6, 2018).
Because this projection was close to the 75 ppb NAAQS, Colorado
developed its DMNFR attainment demonstration using a weight-of-evidence
analysis, as recommended by EPA guidance. Id. at 14812. Colorado's
weight-of-evidence analysis included two modeling analyses in addition
to the primary (3x3 matrix) analysis. The first was performed using a
7x7 matrix of grid cells around each receptor. Colorado contended that
this model performed better than the 3x3 matrix in simulating the 2011
period when monitored concentrations were compared to model results in
the 7x7 matrix, potentially as a result of challenges in accurately
simulating meteorological data in Colorado's complex terrain combined
with the use of a high resolution 4-km grid in the Colorado modeling
platform. In this modeling analysis, Colorado modeled the Douglas
County receptor as attaining the NAAQS in 2017 with a projected
concentration of 75 ppb. Id. All other receptors in the Denver ozone
moderate nonattainment area were also projected as attainment in the
modeling analysis using the 7x7 matrix.
In the second modeling analysis, Colorado evaluated high ozone days
from 2009 to 2013 that were likely influenced by atypical, extreme, or
unrepresentative events (collectively, ``atypical events'') such as
wildfire or stratospheric intrusion, but were included in the
calculation of the 2011 baseline ozone design value.\8\ Colorado did
not submit formal demonstrations under the Exceptional Events Rule (40
CFR 50.14) for these days because they do not affect the DMNFR's
attainment status and thus do not have regulatory significance under
the Exceptional Events Rule. However, these days do affect the baseline
design value and thus affect the model projected future design value
for 2017. After removing the data that were likely influenced by
atypical events, Colorado modeled attainment in 2017 at the Douglas
County receptor using both the 3x3 (74 ppb) and 7x7 (73 ppb) matrices
for calculating the model RRF. Id. at 14813. All other receptors in the
DMNFR ozone Moderate nonattainment area were also projected as
attainment in 2017 when atypical event-influenced data were removed
from the baseline calculation, with the highest projection at any
receptor in the area at 74 ppb. As noted in Section II, the EPA
concurred with Colorado's assessment that this modeling was appropriate
for Colorado's weight of evidence attainment demonstration, and
subsequently finalized our approval of Colorado's attainment
demonstration. 83 FR 31068 (July 3, 2018).
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\8\ See Colorado's November 17, 2016 TSD ``Analyses in Support
of Exceptional Event Flagging and Exclusion for the Weight of
Evidence Analysis,'' in the docket for this action.
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While Wyoming listed the DMNFR attainment demonstration modeling
results as evidence that the Douglas County receptor should not be
considered a maintenance receptor as of 2017, the EPA did not reach the
same conclusion based on these results alone. This is because the
Colorado modeling results, while appropriate in an attainment planning
context, were calculated from a baseline design value that is the
weighted average of three 3-year design values. In an interstate
transport modeling context, EPA evaluates the transport contribution
for both the weighted average design value and individually for each of
the three 3-year average design values. As noted in Section I of this
proposed action, in the CSAPR Update the EPA identified as
``nonattainment receptors'' monitoring sites with a current measured
value exceeding the NAAQS that also have a projected average design
value exceeding the NAAQS and identified maintenance receptors as those
monitoring sites with a projected maximum design value exceeding the
NAAQS. Colorado's DMNFR attainment demonstration modeling results
calculated the 2011 baseline by averaging the three relevant design
values (2009-2011, 2010-2012, and 2011-2013). Therefore, the 2017
modeled projections presented in the DMNFR attainment demonstration
(and referenced by Wyoming) would only have some relevance with regard
to whether the Douglas County receptor should be identified as a
nonattainment receptor in an interstate transport context. However, the
determination of whether the Douglas County receptor should continue to
be identified as a maintenance receptor, as it was in the CSAPR Update
modeling, is based on the 2017 projection of the maximum of
[[Page 3393]]
the three base year design values (in this case, 2011-2013).
Nonetheless, the information regarding atypical event-influenced
data in the DMNFR attainment demonstration is relevant to the
determination of whether the Douglas County monitor should continue to
be identified as a maintenance receptor in the EPA's 2017 modeling for
the 2008 ozone NAAQS. Because the CSAPR Update modeling was conducted
in 2016, the EPA did not consider Colorado's ``Analyses in Support of
Exceptional Event Flagging and Exclusion for the Weight of Evidence
Analysis'' in the CSAPR Update modeling.\9\ After reviewing this
document, the EPA finds it appropriate to consider the impact of
removing atypical event-influenced data from the CSAPR Update modeling
baseline as part of our review of Wyoming's prong 2 weight-of-evidence
analysis. After removal of the atypical event-influenced data from the
2009-2013 baseline, listed in Table 1 below, the baseline maximum
design value at the Douglas County receptor (2011-2013) decreases from
83 ppb to 81 ppb, as shown in Table 2.
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\9\ As noted, this document is available in the docket for this
proposed action.
Table 1--Douglas County Ozone Monitoring Data Flagged as Atypical Event and Excluded From Baseline Design Value Calculation
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Date April 13, 2010 June 7, 2011 July 4, 2012 August 9, 2012 August 21, 2012
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8-hour Ozone Concentration (ppb).................... 79 84 96 98 80
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Table 2--Douglas County Ozone Monitoring With Data Flagged as Atypical Event Included and Excluded
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2011-2013 DV
Year 2011 2012 2013 (truncated)
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4th Max Monitored Value with Atypical Event Data Included 82 86 83 83
(ppb).....................................................
4th Max Monitored Value with Atypical Event Data Excluded 81 79 83 81
(ppb).....................................................
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We then applied the RRF from the CSAPR Update Modeling to this
adjusted design value, and the results are shown in Table 3 below.\10\
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\10\ The EPA notes that the RRFs are based on the ``3x3''
approach as recommended in EPA's Draft Modeling Guidance for
Demonstrating Attainment of the Air Quality Goals for Ozone,
PM2.5, and Regional Haze, December 2014.
Table 3--Revised CSAPR Update Modeling Maximum Design Value for the Douglas County Receptor
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2009-2013 Max DV with CSAPR Update Modeling 2017
2009-2013 Max DV atypical event data CSAPR Update Modeling 2017 CSAPR Update Modeling 2017 Max DV with atypical event
excluded RRF Max DV data excluded
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83...................................... 81 .9358 77.6 75.8
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The projected maximum design value of 75.8 shown in Table 3 (which
excludes monitoring data determined by Colorado to be influenced by
atypical events from the baseline period) indicates attainment of the
2008 ozone NAAQS at the Douglas County receptor in 2017. On this basis,
the EPA is proposing to concur with Wyoming's assertion that the
Douglas County receptor should not be considered a maintenance receptor
at step 1 of the four-step interstate transport framework.
In its weight of evidence analysis, WDEQ also asserted that the
modeling from the EPA's October 2017 Memo indicates no areas in the
United States are expected to have problems attaining and maintaining
the 2008 ozone NAAQS in 2023 outside of California. This includes a
projection of attainment for each receptor in the DMNFR Moderate
nonattainment area, most notably the Douglas County receptor. The EPA
finds that the modeling from the EPA's October 2017 Memo supports the
analysis above regarding whether emissions from Wyoming will interfere
with maintenance of the 2008 ozone NAAQS. Details about this modeling
analysis are provided in the October 2017 Memo, which is available in
the docket for this action.
As with the CSAPR Update, the EPA used the results of the October
2017 Memo modeling to identify as nonattainment receptors those
monitors that both measure nonattainment based on measured 2014-2016
design values and have a projected average design value exceeding the
2008 ozone NAAQS in 2023 and identify receptors that have a projected
maximum design value exceeding the NAAQS in 2023 as maintenance
receptors.
The October 2017 Memo modeling results indicate that Wyoming
emissions will not interfere with maintenance at the Douglas County
receptor or elsewhere in the DMNFR Moderate nonattainment area in 2023,
because each receptor in the area is projected to attain and maintain
the NAAQS in that year. Table 4, below, shows the projected 2023
maximum design values for the three receptors in Colorado that had been
projected as maintenance (there were no projected nonattainment
receptors in the state) for the year 2017 in the CSAPR Update modeling.
Table 4 also shows the projected maximum design values for these
receptors when the 2010-2012 DMNFR monitor values that were likely
influenced by atypical events were removed from the 2011 baseline, as
this baseline was also used for the October 2017 Memo modeling.
[[Page 3394]]
Table 4--Modeled 2023 Maximum Design Values for Colorado Receptors Previously Modeled as Maintenance
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Modeled 2023 Modeled 2023 Max Design
Max Design Value with Atypical Event
Monitor I.D. County Value Data Excluded from 2011
(ppb)\11\ baseline
----------------------------------------------------------------------------------------------------------------
80350004......................... Douglas, CO..................... 73.2 71.5
80590006......................... Jefferson, CO................... 73.7 71.1
80590011......................... Jefferson, CO................... 73.9 72.1
----------------------------------------------------------------------------------------------------------------
The modeled 73.9 ppb projection at one of the Jefferson County,
Colorado receptors is the highest maximum design value for any receptor
in the DMNFR Moderate nonattainment area (and the state overall). This
decreases to a 72.1 maximum design value when the atypical event-
influenced data in the DMNFR are removed from the model's 2011
baseline. As noted by WDEQ in its October 17, 2018 submission, the only
2008 ozone maintenance receptors projected in 2023 are located in the
state of California. Wyoming's highest modeled contribution to any
projected 2023 maintenance receptor is 0.02 ppb (less than 0.03% of the
NAAQS) in Kern County, California (monitor I.D. 60295002).\12\
Therefore, the EPA proposes to find that emissions from Wyoming will
not interfere with maintenance at any area [or monitor] outside of
California in 2023, because there are no projected maintenance
receptors outside of California in that year. Moreover, the EPA
proposes to find emissions from Wyoming will not interfere with any
projected maintenance receptors in California in 2023 because their
modeled contribution at each such receptor is well below 1% of the 2008
ozone NAAQS at step 2 of the four-step framework.
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\11\See October 2017 Memo at page A-7.
\12\ See the EPA's March 27, 2018 Memo ``Information on the
Interstate Transport State Implementation Plan Submissions for the
2015 Ozone National Ambient Air Quality Standards under Clean Air
Act Section 110(a)(2)(D)(i)(I),'' at page C-6.
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In referencing the modeling from both the EPA's October 2017 Memo
and Colorado's DMNFR attainment demonstration, WDEQ asserted that the
Douglas County receptor is projected to attain and maintain the NAAQS
in both 2017 and 2023. On this basis, there would be no requirement for
any state to address upwind ozone contributions to the Douglas County
receptor in advance of 2023, because Colorado's DMNFR attainment
demonstration modeling projects the 2008 ozone NAAQS is currently being
met.\13\ As just discussed, the EPA finds that the relevance of the
DMNFR attainment demonstration modeling to Wyoming's weight-of-evidence
analysis is not the projection of attainment Wyoming references,
because that modeling does not project a maximum design value as is
done in interstate transport modeling. Rather, the relevance of the
DMNFR attainment demonstration is the showing that monitor values from
the 2011 baseline were likely influenced by atypical events, which
supports the EPA's exclusion of the same values from the CSAPR Update
modeling and shows that the Douglas County monitor should not be
identified as a maintenance receptor in 2017. Based on the EPA's review
of the two modeling analyses referenced in WDEQ's submission, and our
additional analysis as described, the EPA is proposing to conclude that
there are no downwind air quality (specifically maintenance) problems
in 2017 to which Wyoming contributes, and that this conclusion is
further bolstered by the October 2017 Memo modeling that shows these
areas will continue to maintain the standard in 2023. Therefore, the
EPA proposes to find that emissions from Wyoming sources will not
interfere with maintenance of the 2008 ozone NAAQS in downwind states.
---------------------------------------------------------------------------
\13\ The EPA is not proposing to make any determinations
regarding the DMNFR Moderate nonattainment area, most notably the
CAA section 181(b)(2) requirement that the EPA determine whether the
area attained the NAAQS by its applicable attainment date.
Colorado's attainment demonstration modeling cited by WDEQ was found
by the EPA to meet the requirements for a modeled demonstration that
the area will meet the standard in the attainment year. 83 FR 31069.
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As discussed in Section II, WDEQ also provided information about
recent and forthcoming ozone precursor emissions reductions in Wyoming.
The EPA agrees with WDEQ that these reductions have been and/or will be
beneficial in reducing ozone transport from Wyoming to downwind states.
However, we did not quantitatively analyze these reductions because of
our proposed finding above that there are no relevant downwind air
quality issues. However, we invite comment on these reductions and
their relevance to our proposed action. Regarding WDEQ's assertion that
the emissions reductions listed in its submission that occurred between
2011 and 2017 do not appear to have been accounted for in the EPA's
2016 CSAPR Update modeling, the CSAPR Update modeling includes all
implemented or scheduled federally enforceable emissions reductions
measures that were known at the time the EPA conducted this modeling,
and therefore, we are not relying on WDEQ's assertion.
B. EPA's Proposed Conclusion
Based on our review of WDEQ's October 17, 2018 submission and other
relevant information, the EPA proposes to concur with WDEQ's conclusion
that Wyoming will not interfere with maintenance of the 2008 ozone
NAAQS in the DMNFR Moderate nonattainment area, specifically the
Douglas County receptor, or in any other downwind state. The EPA is
therefore proposing to approve Wyoming's October 17, 2018 submittal,
which states that Wyoming's SIP includes adequate provisions to
prohibit sources or other emission activities within the State from
emitting ozone precursors in amounts that will interfere with
maintenance by any other state with respect to the 2008 ozone NAAQS.
IV. Proposed Action
The EPA is proposing to fully approve Wyoming's October 17, 2018
submittal addressing CAA section 110(a)(2)(D)(i)(I), prong 2, for the
2008 ozone NAAQS. Should we finalize this proposed approval, the EPA
will no longer have an obligation under CAA section 110(c)(1) to
promulgate a FIP addressing the previous disapproval. The EPA is
soliciting public comments on this proposed action and will consider
public comments received during the comment period.
V. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the Act and applicable
federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, the
[[Page 3395]]
EPA's role is to approve state choices, provided that they meet the
criteria of the CAA. Accordingly, this action merely proposes to
approve state law as meeting federal requirements and does not impose
additional requirements beyond those imposed by state law. For that
reason, this action:
Is not a ``significant regulatory action'' subject to
review by the Office of Management and Budget under Executive Orders
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21,
2011);
Is not an Executive Order 13771 (82 FR 9339, February 2,
2017) regulatory action because SIP approvals are exempted under
Executive Order 12866;
Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Public Law 104-4);
Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
Is not an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001);
Is not subject to requirements of section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the CAA; and
Does not provide the EPA with the discretionary authority
to address, as appropriate, disproportionate human health or
environmental effects, using practicable and legally permissible
methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).
In addition, the SIP is not approved to apply on any Indian reservation
land or in any other area where the EPA or an Indian tribe has
demonstrated that a tribe has jurisdiction. In those areas of Indian
country, the proposed rule does not have tribal implications and will
not impose substantial direct costs on tribal governments or preempt
tribal law as specified by Executive Order 13175 (65 FR 67249, November
9, 2000).
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Carbon monoxide,
Incorporation by reference, Intergovernmental relations, Greenhouse
gases, Lead, Nitrogen dioxide, Ozone, Particulate matter, Reporting and
recordkeeping requirements, Sulfur oxides, Volatile organic compounds.
Authority: 42 U.S.C. 7401 et seq.
Dated: February 6, 2019.
Douglas Benevento,
Regional Administrator, EPA Region 8.
[FR Doc. 2019-01908 Filed 2-11-19; 8:45 am]
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