[Federal Register Volume 83, Number 132 (Tuesday, July 10, 2018)]
[Proposed Rules]
[Pages 31915-31939]
[FR Doc No: 2018-14737]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-HQ-OAR-2018-0225; FRL-9980-53-OAR]
RIN 2060-AT92

Determination Regarding Good Neighbor Obligations for the 2008
Ozone National Ambient Air Quality Standard

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The EPA is proposing to determine that the Cross-State Air
Pollution Rule Update for the 2008 ozone National Ambient Air Quality
Standards (NAAQS) (CSAPR Update) fully addresses certain states'
obligations under Clean Air Act (CAA) section 110(a)(2)(D)(i)(I)
regarding interstate pollution transport for the 2008 ozone NAAQS. The
CSAPR Update, published on October 26, 2016, promulgated Federal
Implementation Plans (FIPs) for 22 states in the eastern U.S. In the
final CSAPR Update, based on information available at that time, the
EPA could not conclude that the rule fully addressed CAA section
110(a)(2)(D)(i)(I) obligations for 21 of the 22 CSAPR Update states.
This action proposes a determination that, based on additional
information and analysis, the CSAPR Update fully addresses this CAA
provision for the 2008 ozone NAAQS for all remaining CSAPR Update
states. Specifically, EPA proposes to determine

that there will be no remaining nonattainment or maintenance receptors
in the eastern U.S. in 2023. Therefore, with the CSAPR Update fully
implemented, these states are not expected to contribute significantly
to nonattainment in, or interfere with maintenance by, any other state
with regard to the 2008 ozone NAAQS. In accord with this proposed
determination, the EPA proposes to determine that it has no
outstanding, unfulfilled obligation under CAA section 110(c)(1) to
establish additional requirements for sources in these states to
further reduce transported ozone pollution under CAA section
110(a)(2)(D)(i)(I) with regard to the 2008 ozone NAAQS. As a result of
this finding, this action proposes minor revisions to the existing
CSAPR Update regulations to reflect that the CSAPR Update FIPs fully
address CAA section 110(a)(2)(D)(i)(I). The proposed determination
would apply to states currently subject to CSAPR Update FIPs as well as
any states for which EPA has approved replacement of CSAPR Update FIPs
with CSAPR Update SIPs.

DATES: Comments must be received on or before August 31, 2018.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2018-0225, at http://www.regulations.gov. Follow the online
instructions for submitting comments. Once submitted, comments cannot
be edited or removed from 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.
    Public hearing. The EPA will be holding one public hearing on the
proposed Determination Regarding Good Neighbor Obligations for the 2008
Ozone National Ambient Air Quality Standard. The hearing will be held
to accept oral comments on the proposal. The hearing will be held on
August 1, 2018 in Washington DC. The hearing will begin at 9:00 a.m.
(local time) and will conclude at 6:00 p.m. (local time) or two hours
after the last registered speaker. The hearing will be held at the
Environmental Protection Agency, William Jefferson Clinton East
Building, Main Floor Room 1153, 1201 Constitution Avenue NW, in
Washington, DC 20460. Because this hearing is being held at a U.S.
government facility, individuals planning to attend the hearing should
be prepared to show valid picture identification to the security staff
in order to gain access to the meeting room. No large signs will be
allowed in the building, cameras may only be used outside of the
building, and demonstrations will not be allowed on federal property
for security reasons. The EPA website for the rulemaking, which
includes the proposal and supporting materials, can be found at https://www.epa.gov/airmarkets/proposed-csapr-close-out.
    If you would like to present oral testimony at the public hearing,
please register online at https://www.epa.gov/airmarkets/forms/public-hearing-proposed-csapr-close-out or contact Mr. Brian Fisher, U.S.
Environmental Protection Agency, Office of Atmospheric Programs, Clean
Air Markets Division, (MS 6204-M), 1200 Pennsylvania Avenue NW,
Washington, DC 20460, telephone<PHONE_NUMBER>, email address is
[email protected], no later than 2 business days prior to the public
hearing. If using email, please provide the following information: Time
you wish to speak (morning, afternoon, evening), name, affiliation,
address, email address, and telephone number.

FOR FURTHER INFORMATION CONTACT: Brian Fisher, Clean Air Markets
Division, Office of Atmospheric Programs, U.S. Environmental Protection
Agency, MC 6204M, 1200 Pennsylvania Avenue NW, Washington, DC 20460;
telephone number:<PHONE_NUMBER>; email address: [email protected].

SUPPLEMENTARY INFORMATION:
    Regulated entities. Entities regulated under the CSAPR Update are
fossil fuel-fired boilers and stationary combustion turbines that serve
generators producing electricity for sale, including combined cycle
units and units operating as part of systems that cogenerate
electricity and other useful energy output. Regulated categories and
entities include:

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                                 NAICS *      Examples of potentially
            Category               code        regulated industries
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Industry.......................   221112  Fossil fuel-fired electric
                                           power generation.
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* North American Industry Classification System.

    This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated. To
determine whether your facility is affected by this action, you should
carefully examine the applicability provisions in 40 CFR 97.804. If you
have questions regarding the applicability of the CSAPR Update to a
particular entity, consult the person listed in the FOR FURTHER
INFORMATION CONTACT section above.
    Outline. The following outline is provided to aid in locating
information in this preamble.

I. General Information
    States Covered by This Action
II. Background and Legal Authority
    A. Ground-Level Ozone Pollution and Public Health
    B. The EPA's Statutory Authority for This Proposed Action
    C. Good Neighbor Obligations for the 2008 Ozone NAAQS
    D. Summary of the CSAPR Update
III. Proposed Determination Regarding Good Neighbor Obligations for
the 2008 Ozone NAAQS
    A. Analytic Approach
    B. Selection of a Future Analytic Year
    1. Attainment Dates for the 2008 Ozone NAAQS
    2. Feasibility of Control Strategies To Reduce Ozone Season
NOX
    3. Focusing on 2023 for Analysis
    C. Air Quality Analysis
    1. Definition of Nonattainment and Maintenance Receptors
    2. Overview of Air Quality Modeling Platform
    3. Emissions Inventories
    4. Air Quality Modeling To Identify Nonattainment and
Maintenance Receptors
    5. Pollutant Transport From Upwind States
    D. Proposed Determination
IV. Statutory Authority and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review, and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Executive Order 13771: Reducing Regulations and Controlling
Regulatory Costs
    C. Paperwork Reduction Act
    D. Regulatory Flexibility Act
    E. Unfunded Mandates Reform Act
    F. Executive Order 13132: Federalism
    G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments

    H. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
    I. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
    J. National Technology Transfer Advancement Act
    K. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
    L. Determinations Under Section 307(b)(1) and (d)

I. General Information

    Within this document ``we,'' ``us,'' or ``our'' should be
interpreted to mean the U.S. EPA.

Where can I get a copy of this document and other related information?

    The EPA has established a docket for this action under Docket ID
No. EPA-HQ-OAR-2018-0225 (available at http://www.regulations.gov).
Information related to the proposed action and the public hearing is
available at the website: https://www.epa.gov/airtransport.

States Covered by This Action

    In the CSAPR Update, 81 FR 74504 (Oct. 26, 2016), the EPA
promulgated FIPs intended to address 22 eastern states' obligations
under CAA section 110(a)(2)(D)(i)(I), also known as the ``good neighbor
provision,'' with respect to the 2008 ozone NAAQS. The good neighbor
provision requires upwind states to control their emissions that impact
air quality problems in downwind states. Based on information available
when the CSAPR Update was finalized, the EPA was unable to determine at
that time that the FIPs fully addressed good neighbor obligations under
this NAAQS for 21 of the 22 states. The EPA has subsequently proposed
to approve a draft SIP which, if finalized, would fully address the
good neighbor obligation for one of these states, Kentucky. In this
action, the EPA proposes to determine that, with CSAPR Update
implementation, the 20 remaining states' good neighbor obligations for
the 2008 ozone NAAQS are fully addressed. In accord with this
determination, the EPA would have no further obligation under CAA
section 110(c) to establish requirements for power plants or any other
emissions sources in these states to further reduce transported ozone
pollution under CAA section 110(a)(2)(D)(i)(I) with regard to this
NAAQS.
    The two states among the 22 CSAPR Update states that are not
covered by this action are Tennessee and Kentucky. With respect to
Tennessee, the EPA already determined in the final CSAPR Update that
implementation of the state's emissions budget would fully eliminate
the state's significant contribution to downwind nonattainment and
interference with maintenance of the 2008 ozone NAAQS because the
downwind air quality problems to which the state was linked were
projected to be resolved after implementation of the CSAPR Update. 81
FR 74540. With respect to Kentucky, the EPA has proposed in a separate
action to approve the state's draft SIP submittal demonstrating that no
additional emissions reductions beyond those required by the CSAPR
Update are necessary to address the state's good neighbor obligation
with respect to the 2008 ozone NAAQS. 83 FR 17123 (April 18, 2018). See
Table I.A-1 for a list of states covered by this proposal.

  Table I.A-1--States Covered by This Proposed Determination Regarding
           Good Neighbor Obligations for the 2008 Ozone NAAQS
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                                  State
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Alabama.
Arkansas.
Illinois.
Indiana.
Iowa.
Kansas.
Louisiana.
Maryland.
Michigan.
Mississippi.
Missouri.
New Jersey.
New York.
Ohio.
Oklahoma.
Pennsylvania.
Texas.
Virginia.
West Virginia.
Wisconsin.
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II. Background and Legal Authority

A. Ground-Level Ozone Pollution and Public Health

    Ground-level ozone causes a variety of negative effects on human
health, vegetation, and ecosystems. In humans, acute and chronic
exposure to ozone is associated with premature mortality and a number
of morbidity effects, such as asthma exacerbation. In ecosystems, ozone
exposure causes visible foliar injury in some plants, decreases growth
in some plants, and affects ecosystem community composition.\1\
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    \1\ For more information on the human health and welfare and
ecosystem effects associated with ambient ozone exposure, see the
EPA's October 2015 Regulatory Impact Analysis of the Final Revisions
to the National Ambient Air Quality Standards for Ground-Level Ozone
(EPA-452/R-15-007) in the docket for this rule and also found in the
docket for the 2015 ozone NAAQS, Docket No. EPA-HQ-OAR-2013-0169-
0057.
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    In this proposed action, consistent with previous rulemakings
described in section II.B, the EPA relies on analysis that reflects the
regional nature of transported ground-level ozone pollution. Ground-
level ozone is not emitted directly into the air, but is a secondary
air pollutant created by chemical reactions between nitrogen oxides
(NOX), carbon monoxide (CO), methane (CH4), and
non-methane volatile organic compounds (VOCs) in the presence of
sunlight. Emissions from mobile sources, electric generating units
(EGUs), industrial facilities, gasoline vapors, and chemical solvents
are some of the major anthropogenic sources of ozone precursors.
NOX emissions from the mobile source category lead all
sectors and were more than double emissions from the second-highest
emitting sector, and accounted from more than half of the national
NOX emissions in 2014.\2\ The potential for ground-level
ozone formation increases during periods with warmer temperatures and
stagnant air masses. Therefore, ozone levels are generally higher
during the summer months.3 4 Ground-level ozone
concentrations and temperature are highly correlated in the eastern
U.S., with observed ozone increases of 2-3 parts per billion (ppb) per
degree Celsius reported.\5\
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    \2\ EPA. 2014 National Emissions Inventory (NEI) v2. Released 2/
2018 and available at https://www.epa.gov/air-emissions-inventories.
    \3\ Rasmussen, D.J. et al. (2011). Ground-level ozone-
temperature relationships in the eastern US: A monthly climatology
for evaluating chemistry-climate models. Atmospheric Environment 47:
142-153.
    \4\ High ozone concentrations have also been observed in cold
months, where a few areas in the western U.S. have experienced high
levels of local VOC and NOX emissions that have formed
ozone when snow is on the ground and temperatures are near or below
freezing.
    \5\ Bloomer, B.J., J.W. Stehr, C.A. Piety, R.J. Salawitch, and
R.R. Dickerson (2009). Observed relationships of ozone air pollution
with temperature and emissions, Geophys. Res. Lett., 36, L09803.
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    Precursor emissions can be transported downwind directly or, after
transformation in the atmosphere, as ozone. Studies have established
that ozone formation, atmospheric residence, and transport occur on a
regional scale (i.e., hundreds of miles) over much of the eastern U.S.
As a result of ozone transport, in any given location, ozone pollution
levels are impacted by a combination of local emissions and emissions
from upwind sources. Numerous observational studies have

demonstrated the transport of ozone and its precursors and the impact
of upwind emissions on high concentrations of ozone pollution.\6\
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    \6\ Bergin, M.S. et al. (2007). Regional air quality: local and
interstate impacts of NOX and SO2 emissions on
ozone and fine particulate matter in the eastern United States.
Environmental Sci & Tech. 41: 4677-4689.
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    The EPA concluded in several previous rulemakings (summarized in
section II.B) that interstate ozone transport can be an important
component of peak ozone concentrations during the summer ozone season
and that NOX control strategies are effective for reducing
regional-scale ozone transport. Model assessments have looked at
impacts on peak ozone concentrations after potential emissions
reduction scenarios for NOX and VOCs for NOX-
limited and VOC-limited areas. For example, Jiang and Fast concluded
that NOX emissions reduction strategies are effective in
lowering ozone mixing ratios in urban areas and Liao et al. showed that
NOX reductions result in lower peak ozone concentrations in
non-attainment areas in the Mid-Atlantic.\7\ Assessments of ozone
conducted for the October 2015 Regulatory Impact Analysis of the Final
Revisions to the National Ambient Air Quality Standards for Ground-
Level Ozone (EPA-452/R-15-007) also show the importance of
NOX emissions on ozone formation. This analysis is in the
docket for this rule and also can be found in the docket for the 2015
ozone NAAQS regulatory impact analysis, Docket No. EPA-HQ-OAR-2013-0169
(document ID EPA-HQ-OAR-2013-0169-0057).
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    \7\ Jiang, G.; Fast, J.D. (2004). Modeling the effects of VOC
and NOX emission sources on ozone formation in Houston
during the TexAQS 2000 field campaign. Atmospheric Environment 38:
5071-5085.
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    Studies have found that NOX emissions reductions can be
effective in reducing ozone pollution as quantified by the form of the
2008 ozone standard, 8-hour peak concentrations. Specifically, studies
have found that NOX emissions reductions from EGUs, mobile
sources, and other source categories can be effective in reducing the
upper-end of the cumulative ozone distribution in the summer on a
regional scale.\8\ Analysis of air quality monitoring data trends shows
reductions in summertime ozone concurrent with implementation of
NOX reduction programs.\9\ Gilliland et al. examined the
NOX SIP Call and presented reductions in observed versus
modeled ozone concentrations in the eastern U.S. downwind from major
NOX sources.\10\ The results showed significant reductions
in ozone concentrations (10-25 percent) from observed measurements
(CASTNET and AQS) \11\ between 2002 and 2005, linking reductions in EGU
NOX emissions from upwind states with ozone reductions
downwind of the major source areas.\12\ Additionally, G[eacute]go et
al. showed that ground-level ozone concentrations were significantly
reduced after implementation of the NOX SIP Call.\13\
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    \8\ Hidy, G.M. and Blanchard C.L. (2015). Precursor reductions
and ground-level ozone in the Continental United States. J. of Air &
Waste Management Assn. 65, 10.
    \9\ Simon, H. et al. (2015). Ozone trends across the United
States over a period of decreasing NOX and VOC emissions.
Environmental Science & Technology 49, 186-195.
    \10\ Gilliland, A.B. et al. (2008). Dynamic evaluation of
regional air quality models: Assessing changes in O3
stemming from changes in emissions and meteorology. Atmospheric
Environment 42: 5110-5123.
    \11\ CASTNET is the EPA's Clean Air Status and Trends Network.
AQS is the EPA's Air Quality System.
    \12\ Hou, Strickland & Liao. ``Contributions of regional air
pollutant emissions to ozone and fine particulate matter-related
mortalities in eastern U.S. urban areas''. Environmental Research,
Feb. 2015. Available at https://ac.els-cdn.com/S0013935114004113/1-s2.0-S0013935114004113-main.pdf?_tid=78c88101-fa6e-4e75-a65c-f56746905e7d&acdnat=1525175812_0e62553b83c9ffa1105aa306a478e8bb
    \13\ G[eacute]go et al. (2007). Observation-based assessment of
the impact of nitrogen oxides emissions reductions on O3
air quality over the eastern United States. J. of Applied
Meteorology and Climatology 46: 994-1008.
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    Mobile sources also account for a large share of the NOX
emissions inventory (i.e., about 7.3 million tons per year in the 2011
base year, which represented more than 50% of continental U.S.
NOX emissions), and the EPA recognizes that emissions
reductions achieved from this sector as well can reduce transported
ozone pollution. The EPA has national programs that serve to reduce
emissions from all contributors to the mobile source inventory (i.e.,
projected NOX emissions reductions of about 4.7 million tons
per year between the 2011 base year and the 2023 future analytical
year). A detailed discussion of the EPA's mobile source emissions
reduction programs can be found at www.epa.gov/otaq.
    In light of the regional nature of ozone transport discussed
herein, and given that NOX emissions from mobile sources are
being addressed in separate national rules, in the CSAPR Update (as in
previous regional ozone transport actions) the EPA relied on regional
analysis and required regional ozone-season NOX emissions
reductions from EGUs to address interstate transport of ozone.

B. The EPA's Statutory Authority for This Proposed Action

    The statutory authority for this proposed action is provided by the
CAA as amended (42 U.S.C. 7401 et seq.). Specifically, sections 110 and
301 of the CAA provide the primary statutory underpinnings for this
rule. The most relevant portions of section 110 are subsections
110(a)(1), 110(a)(2) (including 110(a)(2)(D)(i)(I)), and 110(c)(1).
    Section 110(a)(1) provides that states must make SIP submissions
``within 3 years (or such shorter period as the Administrator may
prescribe) after the promulgation of a national primary ambient air
quality standard (or any revision thereof),'' and that these SIP
submissions are to provide for the ``implementation, maintenance, and
enforcement'' of such NAAQS.\14\ The statute directly imposes on states
the duty to make these SIP submissions, and the requirement to make the
submissions is not conditioned upon the EPA taking any action other
than promulgating a new or revised NAAQS.\15\
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    \14\ 42 U.S.C. 7410(a)(1).
    \15\ See EPA v. EME Homer City Generation, L.P., 134 S. Ct.
1584, 1601 (2014).
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    The EPA has historically referred to SIP submissions made for the
purpose of satisfying the applicable requirements of CAA sections
110(a)(1) and 110(a)(2) as ``infrastructure SIP'' submissions. Section
110(a)(1) addresses the timing and general requirements for
infrastructure SIP submissions, and section 110(a)(2) provides more
details concerning the required content of these submissions. It
includes a list of specific elements that ``[e]ach such plan''
submission must address.\16\ All states, regardless of whether the
state includes areas designated as nonattainment for the relevant
NAAQS, must have SIPs that meet the applicable requirements of section
110(a)(2), including provisions of section 110(a)(2)(D)(i)(I) described
later and that are the focus of this rule.
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    \16\ The EPA's general approach to infrastructure SIP
submissions is explained in greater detail in individual notices
acting or proposing to act on state infrastructure SIP submissions
and in guidance. See, e.g., Memorandum from Stephen D. Page on
Guidance on Infrastructure State Implementation Plan (SIP) Elements
under Clean Air Act Sections 110(a)(1) and 110(a)(2) (Sept. 13,
2013).
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    Section 110(c)(1) requires the Administrator to promulgate a FIP at
any time within two years after the Administrator: (1) Finds that a
state has failed to make a required SIP submission; (2) finds a SIP
submission to be incomplete pursuant to CAA section 110(k)(1)(C); or
(3) disapproves

a SIP submission, unless the state corrects the deficiency through a
SIP revision that the Administrator approves before the FIP is
promulgated.\17\
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    \17\ 42 U.S.C. 7410(c)(1).
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    Section 110(a)(2)(D)(i)(I), also known as the ``good neighbor
provision,'' provides the primary basis for this action. It requires
that each state SIP shall include provisions sufficient to ``prohibit[
] . . . any source or other type of emissions activity within the State
from emitting any air pollutant in amounts which will--(I) contribute
significantly to nonattainment in, or interfere with maintenance by,
any other State with respect to any [NAAQS].'' \18\
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    \18\ 42 U.S.C. 7410(a)(2)(D)(i)(I).
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    The EPA has previously issued four rules interpreting and
clarifying the requirements of section 110(a)(2)(D)(i)(I) for states in
the eastern United States. These rules, and the associated court
decisions addressing these rules, summarized here, provide important
guidance regarding the requirements of section 110(a)(2)(D)(i)(I).
    The NOX SIP Call, promulgated in 1998, addressed the
good neighbor provision for the 1979 1-hour ozone NAAQS.\19\ The rule
required 22 states and the District of Columbia to amend their SIPs to
reduce NOX emissions that contribute to ozone nonattainment
in downwind states. The EPA set an ozone season NOX budget
for each covered state, essentially a cap on ozone season
NOX emissions in the state. Covered states were given the
option to participate in a regional cap-and-trade program, known as the
NOX Budget Trading Program (NBP), to achieve a large portion
of the reductions. The United States Court of Appeals for the District
of Columbia Circuit (D.C. Circuit) largely upheld the NOX
SIP Call in Michigan v. EPA, 213 F.3d 663 (D.C. Cir. 2000), cert.
denied, 532 U.S. 904 (2001).
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    \19\ 63 FR 57356 (Oct. 27, 1998). As originally promulgated, the
NOX SIP Call also addressed good neighbor obligations
under the 1997 8-hour ozone NAAQS, but the EPA subsequently stayed
the rule's provisions with respect to that standard. 40 CFR
51.121(q).
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    The EPA's next rule addressing the good neighbor provision, Clean
Air Interstate Rule (CAIR), was promulgated in 2005 and addressed both
the 1997 PM2.5 and 1997 ozone NAAQS.\20\ CAIR required SIP
revisions in 28 states and the District of Columbia to reduce emissions
of sulfur dioxide (SO2) and/or NOX--important
precursors of regionally transported PM2.5 (SO2
and NOX) and ozone (NOX). As in the
NOX SIP Call, states were given the option to participate in
regional cap-and-trade programs to achieve the reductions. When the EPA
promulgated the final CAIR in May 2005, the EPA also issued a national
rule, finding that states had failed to submit SIPs to address the
requirements of CAA section 110(a)(2)(D)(i) with respect to the 1997
PM2.5 and 1997 ozone NAAQS. Those states were required by
the CAA to have submitted good neighbor SIPs for those standards by
July 2000 (i.e., three years after the standards were finalized).\21\
These findings of failure to submit triggered a 2-year clock for the
EPA to issue FIPs to address interstate transport,\22\ and on March 15,
2006, the EPA promulgated FIPs to ensure that the emissions reductions
required by CAIR would be achieved on schedule.\23\ CAIR was remanded
to the EPA by the D.C. Circuit in North Carolina v. EPA, 531 F.3d 896
(D.C. Cir. 2008), modified on reh'g, 550 F.3d 1176. For more
information on the legal issues underlying CAIR and the D.C. Circuit's
holding in North Carolina, refer to the preamble of the original
CSAPR.\24\
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    \20\ 70 FR 25162 (May 12, 2005).
    \21\ 70 FR 21147 (May 12, 2005). See n.14 and main text, supra.
    \22\ See n.17 and main text, supra.
    \23\ 71 FR 25328 (April 28, 2006).
    \24\ 76 FR 48208, 48217 (Aug. 8, 2011).
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    In 2011, the EPA promulgated the original CSAPR to address the
issues raised by the remand of CAIR. CSAPR addressed the two NAAQS at
issue in CAIR and additionally addressed the good neighbor provision
for the 2006 PM2.5 NAAQS.\25\ CSAPR required 28 states to
reduce SO2 emissions, annual NOX emissions, and/
or ozone season NOX emissions that significantly contribute
to other states' nonattainment or interfere with other states'
abilities to maintain these air quality standards. To align
implementation with the applicable attainment deadlines, the EPA
promulgated FIPs for each of the 28 states covered by CSAPR. The FIPs
implement regional cap-and-trade programs to achieve the necessary
emissions reductions. Each state can submit a good neighbor SIP at any
time that, if approved by the EPA, would replace the CSAPR FIP for that
state.\26\ CSAPR was the subject of an adverse decision by the D.C.
Circuit in August 2012,\27\ reversed in April 2014 by the Supreme
Court,\28\ which largely upheld the rule, including EPA's approach to
addressing interstate transport in CSAPR, but remanded to the D.C.
Circuit to consider other claims not addressed by the Court. EPA v. EME
Homer City Generation, L.P., 134 S. Ct. 1584 (2014). On remand from the
Supreme Court, in July 2015 the D.C. Circuit affirmed the EPA's
interpretation of various statutory provisions and the EPA's technical
decisions. EME Homer City Generation, L.P. v. EPA, 795 F.3d 118 (2015)
(EME Homer City II). However, the court also remanded the rule without
vacatur for reconsideration of the EPA's emissions budgets for certain
states, which the court found may over-control those states' emissions
with respect to the downwind air quality problems to which the states
were linked. Id. at 129-30, 138. For more information on the legal
considerations of CSAPR and the court's decisions in the EME Homer City
litigation, refer to the preamble of the CSAPR Update.\29\
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    \25\ 76 FR 48208.
    \26\ EPA has already approved SIPs fully replacing the original
CSAPR FIPs for Alabama, 81 FR 59869 (Aug. 31, 2016), Georgia, 82 FR
47930 (Oct. 13, 2017), and South Carolina, 82 FR 47936 (Oct. 13,
2017).
    \27\ On August 21, 2012, the D.C. Circuit issued a decision in
EME Homer City Generation, L.P. v. EPA, 696 F.3d 7 (D.C. Cir. 2012)
(EME Homer I), vacating CSAPR. The EPA sought review with the D.C.
Circuit en banc and the D.C. Circuit declined to consider the EPA's
appeal en banc. EME Homer City Generation, L.P. v. EPA, No. 11-1302
(D.C. Cir. January 24, 2013), ECF No. 1417012 (denying the EPA's
motion for rehearing en banc).
    \28\ On January 23, 2013, the Supreme Court granted the EPA's
petition for certiorari. EPA v. EME Homer City Generation, L.P., 133
S. Ct. 2857 (2013) (granting the EPA's and other parties' petitions
for certiorari). On April 29, 2014, the Supreme Court issued a
decision reversing the D.C. Circuit's EME Homer City opinion.
    \29\ 81 FR 74511.
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    In 2016, the EPA promulgated the CSAPR Update to address interstate
transport of ozone pollution with respect to the 2008 ozone NAAQS. The
final rule generally updated the CSAPR ozone season NOX
emissions budgets for 22 states to achieve cost-effective
NOX emissions reductions from EGUs within those states.\30\
The CSAPR Update implemented these budgets through FIPs requiring
sources to participate in a revised CSAPR ozone season NOX
allowance trading program. As under the original CSAPR, each state can
submit a good neighbor SIP at any time that, if approved by the EPA,
would replace the CSAPR Update FIP for that state.\31\ The final CSAPR
Update also addressed the remand by the D.C. Circuit of certain states'
original CSAPR phase 2 ozone season NOX emissions budgets in
EME Homer City II. The CSAPR Update is subject to pending

legal challenges in the D.C. Circuit. Wisconsin v. EPA, No. 16-1406
(D.C. Cir. filed Nov. 23, 2016). Further information about the CSAPR
Update can be found in section II.D of this notice.
---------------------------------------------------------------------------

    \30\ One state, Kansas, was made newly subject to a CSAPR ozone
season NOX requirement by the CSAPR Update. All other
CSAPR Update states were already subject to ozone season
NOX requirements under the original CSAPR.
    \31\ EPA has already approved a SIP fully replacing the CSAPR
Update FIP for Alabama. 82 FR 46674 (Oct. 6, 2017).
---------------------------------------------------------------------------

    Section 301(a)(1) of the CAA also gives the Administrator the
general authority to prescribe such regulations as are necessary to
carry out functions under the Act.\32\ Pursuant to this section, the
EPA has authority to clarify the applicability of CAA requirements. In
this action, among other things, the EPA is clarifying the
applicability of section 110(a)(2)(D)(i)(I) with respect to the 2008
ozone NAAQS. In particular, the EPA is using its authority under
sections 110 and 301 to make a determination that no further
enforceable reductions in emissions of NOX are required
under this provision with respect to the 2008 ozone NAAQS for the
states covered by this rule. The EPA is making minor revisions to the
existing state-specific sections of the CSAPR Update regulations for
all states covered by that action other than Kentucky and Tennessee.
---------------------------------------------------------------------------

    \32\ 42 U.S.C. 7601(a)(1).
---------------------------------------------------------------------------

C. Good Neighbor Obligations for the 2008 Ozone NAAQS

    On March 12, 2008, the EPA promulgated a revision to the NAAQS,
lowering both the primary and secondary standards to 75 ppb. See
National Ambient Air Quality Standards for Ozone, Final Rule, 73 FR
16436 (March 27, 2008). Specifically, the standards require that an
area may not exceed 75 ppb using the 3-year average of the fourth
highest 24-hour maximum 8-hour rolling average ozone concentration.
These revisions of the NAAQS, in turn, triggered a 3-year deadline for
states to submit SIP revisions addressing infrastructure requirements
under CAA sections 110(a)(1) and 110(a)(2), including the good neighbor
provision. Several events affected application of the good neighbor
provision for the 2008 ozone NAAQS, including reconsideration of the
2008 ozone NAAQS and legal developments pertaining to the EPA's
original CSAPR, which created uncertainty surrounding the EPA's
statutory interpretation and implementation of the good neighbor
provision.\33\ Notwithstanding these events, EPA ultimately affirmed
that states' good neighbor SIPs were due on March 12, 2011.
---------------------------------------------------------------------------

    \33\ These events are described in detail in section IV.A.2 of
the CSAPR Update. 81 FR 74515.
---------------------------------------------------------------------------

    The EPA subsequently took several actions that triggered the EPA's
obligation under CAA section 110(c) to promulgate FIPs addressing the
good neighbor provision for several states.\34\ First, on July 13,
2015, the EPA published a rule finding that 24 states failed to make
complete submissions that address the requirements of section
110(a)(2)(D)(i)(I) related to the interstate transport of pollution as
to the 2008 ozone NAAQS. See 80 FR 39961 (effective August 12, 2015).
The finding action triggered a 2-year deadline for the EPA to issue
FIPs to address the good neighbor provision for these states by August
12, 2017. The CSAPR Update finalized FIPs for 13 of these states
(Alabama, Arkansas, Illinois, Iowa, Kansas, Michigan, Mississippi,
Missouri, Oklahoma, Pennsylvania, Tennessee, Virginia, and West
Virginia). The EPA also determined in the CSAPR Update that the Agency
had fully satisfied its FIP obligation as to nine additional states
identified in the finding of failure to submit (Florida, Georgia,
Maine, Massachusetts, Minnesota, New Hampshire, North Carolina, South
Carolina, and Vermont). The EPA determined that these states did not
contribute significantly to nonattainment in, or interfere with
maintenance by, any other state with respect to the 2008 ozone NAAQS.
81 FR 74506.\35\ On June 15, 2016 and July 20, 2016, the EPA published
additional rules finding that New Jersey and Maryland, respectively,
also failed to submit transport SIPs for the 2008 ozone NAAQS. See 81
FR 38963 (June 15, 2016) (effective July 15, 2016); 81 FR 47040 (July
20, 2016) (Maryland, effective August 19, 2016). The finding actions
triggered 2-year deadlines for the EPA to issue FIPs to address the
good neighbor provision for Maryland by August 19, 2018, and New Jersey
by July 15, 2018. The CSAPR Update finalized FIPs for these two states.
---------------------------------------------------------------------------

    \34\ This section of the preamble focuses on SIP and FIP actions
for those states addressed in the CSAPR Update. The EPA has also
acted on SIPs for other states not mentioned in this action. The
memorandum, Status of 110(a)(2)(D)(i)(I) SIPs for the 2008 Ozone
NAAQS, more fully describes the good neighbor SIP status for the
2008 ozone NAAQS and is available in the docket for this action.
    \35\ The two remaining states addressed in the findings of
failure to submit (California and New Mexico) were not part of the
CSAPR Update analysis and are not addressed in this rulemaking.
---------------------------------------------------------------------------

    In addition to the previously identified finding actions, the EPA
also finalized disapproval or partial disapproval actions for SIPs
submitted by Indiana, Kentucky, Louisiana, New York, Ohio, Texas, and
Wisconsin.\36\ These disapprovals triggered the EPA's obligation to
promulgate FIPs to implement the requirements of the good neighbor
provision for those states within 2 years of the effective date of each
disapproval. The EPA promulgated CSAPR Update FIPs for Indiana,
Kentucky, Louisiana, New York, Ohio, Texas, and Wisconsin.
---------------------------------------------------------------------------

    \36\ See the following actions: Indiana (81 FR 38957, June 15,
2016); Kentucky (78 FR 14681, March 7, 2013); Louisiana (81 FR
53308, August 12, 2016); New York (81 FR 58849, August 26, 2016);
Ohio (81 FR 38957, June 15, 2016); Texas (81 FR 53284, August 12,
2016); and Wisconsin (81 FR 53309, August 12, 2016).
---------------------------------------------------------------------------

    As discussed in more detail in the next section, in issuing the
CSAPR Update, the EPA did not determine that it had entirely addressed
the EPA's outstanding CAA obligations to implement the good neighbor
provision with respect to the 2008 ozone NAAQS for 21 of 22 states
covered by that rule. Accordingly, the CSAPR Update did not fully
satisfy the EPA's obligation to address the good neighbor provision
requirements for those states by approving SIPs, issuing FIPs, or some
combination of those two actions. The EPA found that the CSAPR Update
FIP fully addressed the good neighbor provision for the 2008 ozone
NAAQS only with respect to Tennessee.
    The EPA notes that it has also already separately proposed an
action to fully address Kentucky's good neighbor obligation for the
2008 ozone NAAQS. 83 FR 17123 (Apr. 18, 2018). On May 23, 2017, the
U.S. District Court for the Northern District of California issued an
order requiring the EPA to take a final action fully addressing the
good neighbor obligation for the 2008 ozone NAAQS for Kentucky by June
30, 2018. See Order, Sierra Club v. Pruitt, No. 3:15-cv-04328 (N.D.
Cal. May 23, 2017). On February 28, 2018, Kentucky submitted to the EPA
a draft SIP addressing the remaining good neighbor obligation. On May
10, 2018, Kentucky submitted their final SIP to EPA. The EPA proposed
to approve the state's draft SIP, 83 FR 17123 (April 18, 2018), and
intends to take an appropriate final action that would address this
obligation for Kentucky consistent with the court-ordered deadline.
    As noted previously, subsequent to the promulgation of the CSAPR
Update, the EPA approved a SIP fully replacing the FIP for Alabama. 82
FR 46674 (October 6, 2017). In that SIP approval, the EPA found that
the rule partially satisfies Alabama's good neighbor obligation for the
2008 ozone NAAQS. Thus, the EPA continues to have an obligation,
stemming from the July 13, 2015 findings notice, to fully address the
good neighbor provision requirements for the 2008 NAAQS with respect to
Alabama. As previously

noted, other states have also submitted SIPs, some of which the EPA has
approved and some of which still remain pending. However, these states
are not the subject of this rulemaking and these actions are therefore
not described in detail in this section.
    Table II.C-1 summarizes the statutory deadline for the EPA to
address its FIP obligation under CAA section 110(c) and the event that
activated the EPA's obligation for each of the 20 remaining CSAPR
Update states addressed in this proposed action. For more information
regarding the actions triggering the EPA's FIP obligation and the EPA's
action on SIPs addressing the good neighbor provision for the 2008
ozone NAAQS, see the memorandum, Status of 110(a)(2)(D)(i)(I) SIPs for
the 2008 Ozone NAAQS, in the docket for this action.

 Table II.C-1--Events That Activated EPA's Obligation and Statutory FIP
                                Deadlines
------------------------------------------------------------------------
                                      Type of action
                                     (Federal Register    Statutory FIP
              State                      citation,        deadline \37\
                                     publication date)
------------------------------------------------------------------------
Alabama..........................  Finding of Failure          8/12/2017
                                    to Submit (80 FR
                                    39961, 7/13/2015).
Arkansas.........................  Finding of Failure          8/12/2017
                                    to Submit (80 FR
                                    39961, 7/13/2015).
Illinois.........................  Finding of Failure          8/12/2017
                                    to Submit (80 FR
                                    39961, 7/13/2015).
Indiana..........................  SIP disapproval (81         7/15/2018
                                    FR 38957, 6/15/
                                    2016).
Iowa.............................  Finding of Failure          8/12/2017
                                    to Submit (80 FR
                                    39961, 7/13/2015).
Kansas...........................  Finding of Failure          8/12/2017
                                    to Submit (80 FR
                                    39961, 7/13/2015).
Louisiana........................  SIP disapproval (81         9/12/2018
                                    FR 53308, 8/12/
                                    2016).
Maryland.........................  Finding of Failure          8/19/2018
                                    to Submit (81 FR
                                    47040, 7/20/2016).
Michigan.........................  Finding of Failure          8/12/2017
                                    to Submit (80 FR
                                    39961, 7/13/2015).
Mississippi......................  Finding of Failure          8/12/2017
                                    to Submit (80 FR
                                    39961, 7/13/2015).
Missouri.........................  Finding of Failure          8/12/2017
                                    to Submit (80 FR
                                    39961, 7/13/2015).
New Jersey.......................  Finding of Failure          7/15/2018
                                    to Submit (81 FR
                                    38963, 6/15/2016).
New York.........................  SIP disapproval (81         9/26/2018
                                    FR 58849, 8/12/
                                    2016).
Ohio.............................  SIP disapproval (81         7/15/2018
                                    FR 38957, 6/15/
                                    2016).
Oklahoma.........................  Finding of Failure          8/12/2017
                                    to Submit (80 FR
                                    39961, 7/13/2015).
Pennsylvania.....................  Finding of Failure          8/12/2017
                                    to Submit (80 FR
                                    39961, 7/13/2015).
Texas............................  SIP disapproval (81         9/12/2018
                                    FR 53284, 8/12/
                                    2016).
Virginia.........................  Finding of Failure          8/12/2017
                                    to Submit (80 FR
                                    39961, 7/13/2015).
West Virginia....................  Finding of Failure          8/12/2017
                                    to Submit (80 FR
                                    39961, 7/13/2015).
Wisconsin........................  Partial SIP                 9/12/2018
                                    disapproval as to
                                    prong 2 (81 FR
                                    53309, 8/12/2016).
------------------------------------------------------------------------

D. Summary of the CSAPR Update
---------------------------------------------------------------------------

    \37\ The FIP deadline is two years from the effective date of
the SIP disapproval or Finding of Failure to Submit, which generally
trails the publication date by 30 or 45 days.
---------------------------------------------------------------------------

    On October 16, 2016, the EPA finalized the CSAPR Update. The
purpose of the CSAPR Update was to protect public health and welfare by
reducing interstate pollution transport that significantly contributes
to nonattainment, or interferes with maintenance, of the 2008 ozone
NAAQS in the eastern U.S. As discussed in section II.C, the EPA
finalized a FIP for each of the 22 states subject to the rule,\38\
either having previously found that those states failed to submit a
complete good neighbor SIP (15 states) or having issued a final rule
disapproving their good neighbor SIP submittals (7 states). For the 22
states covered by the CSAPR Update, the EPA promulgated EGU ozone
season NOX emissions budgets, implemented through a regional
allowance trading program, to reduce interstate ozone transport for the
2008 ozone NAAQS during the ozone season (May-September), beginning
with the 2017 ozone season.
---------------------------------------------------------------------------

    \38\ Alabama, Arkansas, Illinois, Indiana, Iowa, Kansas,
Kentucky, Louisiana, Maryland, Michigan, Mississippi, Missouri, New
Jersey, New York, Ohio, Oklahoma, Pennsylvania, Tennessee, Texas,
Virginia, West Virginia, and Wisconsin.
---------------------------------------------------------------------------

    The EPA aligned its analysis for the CSAPR Update (and
implementation of the trading program) with relevant attainment dates
for the 2008 ozone NAAQS, consistent with the D.C. Circuit's decision
in North Carolina v. EPA.\39\ The EPA's final 2008 Ozone NAAQS SIP
Requirements Rule established the attainment deadline of July 20, 2018
for ozone nonattainment areas classified as Moderate.\40\ Because the
attainment date falls during the 2018 ozone season, the 2017 ozone
season was the last full season from which data could be used to
determine attainment of the NAAQS by the July 20, 2018 attainment date.
Therefore, consistent with the court's instruction in North Carolina,
the EPA established and implemented emissions budgets starting with the
2017 ozone season. 81 FR 74507.
---------------------------------------------------------------------------

    \39\ 531 F.3d 896, 911-12 (D.C. Cir. 2008) (holding that the EPA
must coordinate interstate transport compliance deadlines with
downwind attainment deadlines).
    \40\ 80 FR 12264, 12268 (Mar. 6, 2015); 40 CFR 51.1103. Ozone
nonattainment areas are classified as either Marginal, Moderate,
Serious, Severe, or Extreme, based on the severity of the air
quality problem in the area. Areas with more acute air quality
problems are required to implement more stringent control
requirements and are provided additional time to attain the NAAQS.
See CAA sections 181 and 182, 42 U.S.C. 7511, 7511a.
---------------------------------------------------------------------------

    To establish the CSAPR Update emissions budgets, the EPA followed a
four-step analytic process that has been used in each of the Agency's
regional interstate transport rulemakings. The four-step interstate
transport framework is described in more detail in section III.A. To
summarize, in step 1, the Agency identified downwind receptors that are
expected to have problems attaining or maintaining the NAAQS. In step
2, the EPA examined which upwind states contribute to the nonattainment
or maintenance receptors identified in step 1. In step 3, the EPA
quantified the upwind emissions that significantly contribute to
nonattainment or interfere with maintenance. The EPA quantified
significantly contributing emissions from upwind states by evaluating
levels of uniform NOX control stringency, represented by an
estimated marginal cost per ton of NOX reduced. The EPA
applied a multi-factor test to evaluate cost, available emissions
reductions, and downwind air quality impacts to determine the
appropriate level of uniform NOX control stringency that
addressed the impacts of interstate transport on downwind nonattainment
or maintenance receptors. The EPA used

this multi-factor assessment to gauge the extent to which emissions
reductions should be implemented beginning in 2017 and to ensure those
reductions do not represent over-control. In step 4, the EPA identified
emissions budgets for significantly contributing states that reflected
the absence of significant contribution and provided for implementation
of the budgets through an allowance trading program.
    The multi-factor test generated a ``knee in the curve,'' i.e., a
point at which the cost-effectiveness of the emissions reductions is
maximized, so named for the discernable turning point observable in a
cost curve. See 81 FR 74550. In the CSAPR Update this was at the point
where emissions budgets reflected a control stringency with an
estimated marginal cost of $1,400 per ton of NOX reduced.
This level of stringency in emissions budgets represented the level at
which incremental EGU NOX reduction potential and
corresponding downwind ozone air quality improvements were maximized--
relative to other cost levels evaluated--with respect to marginal cost.
That is, the ratio of emissions reductions to marginal cost and the
ratio of ozone improvements to marginal cost were maximized relative to
the other emissions budget levels evaluated. The EPA found that highly
cost-effective EGU NOX reductions were available to make
meaningful and timely improvements in downwind ozone air quality to
address interstate ozone transport for the 2008 ozone NAAQS for the
2017 ozone season. 81 FR 74508. Further, the agency's evaluation showed
that emissions budgets reflecting the $1,400 per ton cost threshold did
not over-control upwind states' emissions relative to either the
downwind air quality problems to which they were linked or the 1
percent contribution threshold in step 2 that triggered their further
evaluation in step 3. Id. at 74551-52. As a result, the EPA finalized
EGU ozone season NOX emissions budgets developed using
uniform control stringency represented by $1,400 per ton.
    To implement the CSAPR Update's emissions reductions, the EPA
promulgated FIPs requiring power plants in covered states to
participate in the CSAPR NOX Ozone Season Group 2 allowance
trading program starting in 2017.\41\ CSAPR's trading programs and the
EPA's prior emissions trading programs (e.g., CAIR and the
NOX Budget Trading Program) provide a proven implementation
framework for achieving emissions reductions. In addition to providing
environmental certainty (i.e., a cap on emissions), these programs also
provide regulated sources with flexibility in choosing compliance
strategies. By using the CSAPR allowance trading programs, the EPA
applied an implementation framework that was shaped by notice and
comment in previous rulemakings and reflected the evolution of these
programs in response to court decisions and practical experience gained
by states, industry, and the EPA.
---------------------------------------------------------------------------

    \41\ The ozone season NOX allowance trading program
created under the original CSAPR was renamed the CSAPR
NOX Ozone Season Group 1 Trading Program and now applies
only to sources in Georgia. In the CSAPR Update, the EPA found that
Georgia did not contribute to interstate transport with respect to
the 2008 ozone NAAQS, but the state has an ongoing ozone season
NOX requirement under the original CSAPR.
---------------------------------------------------------------------------

    Based on information available at the time of its promulgation, the
EPA was unable to conclude that the CSAPR Update fully addressed most
of the covered states' good neighbor obligations for the 2008 ozone
NAAQS. 81 FR 74521. Information available at the time indicated that,
even with CSAPR Update implementation, several downwind receptors were
expected to continue having problems attaining and maintaining this
NAAQS and that emissions from upwind states were expected to continue
to contribute greater than or equal to 1 percent of the NAAQS to these
areas during the 2017 ozone season. Id. at 74551-52. Further, the EPA
could not conclude at that time whether additional EGU and non-EGU
reductions implemented on a longer timeframe than 2017 would be
feasible and cost-effective to address states' good neighbor
obligations for this NAAQS.
    As noted, the EPA premised its conclusion that the CSAPR Update may
not fully address states' good neighbor obligations in part on the
Agency's assessment that air quality problems would persist at downwind
receptors in 2017 even with CSAPR Update implementation. The EPA's
assessment of CSAPR Update implementation using the Air Quality
Assessment Tool (AQAT) indicated that certain eastern air quality
monitors would continue to have problems attaining and maintaining the
2008 ozone NAAQS in 2017. 81 FR 74550-52. Specifically, projected
nonattainment receptors remained in Connecticut, Texas, and Wisconsin,
while projected maintenance-only receptors remained in Connecticut,
Maryland, Michigan, New York, and Texas.\42\ See Table II.C-1 for a
list of remaining nonattainment receptors and Table II.C-2 for a list
of remaining maintenance-only receptors. (The EPA's approach to
defining nonattainment and maintenance-only receptors is explained in
section III.C.1 below.)
---------------------------------------------------------------------------

    \42\ Projected AQAT design values for the $1400/ton policy case
are available in Tables D-6 and D-7 of the CSAPR Update ``Ozone
Transport Policy Analysis Final Rule TSD'' (August 2016), Docket ID
No. EPA-HQ-OAR-2015-0500-0555.

  Table II.C-2--Remaining 2017 Projected Nonattainment Receptors in the
                              Eastern U.S.
------------------------------------------------------------------------
      Monitor ID                 State                    County
------------------------------------------------------------------------
090019003.............  Connecticut............  Fairfield.
090099002.............  Connecticut............  New Haven.
480391004.............  Texas..................  Brazoria.
484392003.............  Texas..................  Tarrant.
484393009.............  Texas..................  Tarrant.
551170006.............  Wisconsin..............  Sheboygan.
------------------------------------------------------------------------

Table II.C-3--Remaining 2017 Projected Maintenance-Only Receptors in the
                              Eastern U.S.
------------------------------------------------------------------------
      Monitor ID                 State                    County
------------------------------------------------------------------------
090010017.............  Connecticut............  Fairfield.
090013007.............  Connecticut............  Fairfield.
240251001.............  Maryland...............  Harford.
260050003.............  Michigan...............  Allegan.
360850067.............  New York...............  Richmond.
361030002.............  New York...............  Suffolk.
481210034.............  Texas..................  Denton.
482010024.............  Texas..................  Harris.
482011034.............  Texas..................  Harris.
482011039.............  Texas..................  Harris.
------------------------------------------------------------------------

    The EPA's analysis also showed that 21 of the 22 CSAPR Update
states would continue to contribute equal to or greater than 1 percent
of the 2008 ozone NAAQS to at least one remaining nonattainment or
maintenance receptor in 2017.\43\ Thus, for those 21 states, the EPA
could not, based on information available in the CSAPR Update
rulemaking, make an air quality-based conclusion that the CSAPR Update
would fully resolve states' good neighbor obligations with respect to
the 2008 ozone NAAQS. (For one state, Tennessee, the EPA determined
that the CSAPR Update fully resolved its good neighbor obligation.)
---------------------------------------------------------------------------

    \43\ See EPA's Air Quality Assessment Tool from the CSAPR Update
in the docket for this rulemaking.
---------------------------------------------------------------------------

    Further, it was not feasible for the EPA to complete an emissions
control analysis that would otherwise be necessary to evaluate full
elimination of each state's significant contribution to nonattainment
or interference with maintenance and also ensure that emissions
reductions would be achieved by 2017. 81 FR at 74522. Specifically, the
EPA was unable to fully consider both non-EGU ozone season
NOX

reductions and further EGU reductions that may have been achievable
after 2017. Id. at 74521. The EPA did not quantify non-EGU stationary
source emissions reductions to address interstate ozone transport for
the 2008 ozone NAAQS in the CSAPR Update for two reasons. First, the
EPA explained that there was greater uncertainty in the EPA's
assessment of non-EGU NOX mitigation potential, and that
more time would be required for states and the EPA to improve non-EGU
point source data and pollution control assumptions before we could
develop emissions reduction obligations based on that data. Id. at
74542. Second, the EPA explained that we did not believe that
significant, certain, and meaningful non-EGU NOX reductions
were feasible for the 2017 ozone season. Id. Many commenters generally
agreed with the EPA that non-EGU emissions reductions were not readily
available for the 2017 ozone season but some advocated that such
reductions should be included as appropriate in future mitigation
actions. Id. at 74521-22. With respect to EGUs, the EPA concluded that
additional control strategies, such as the implementation of new post-
combustion controls, would take several years to implement, which was
beyond the 2017 ozone season targeted in the CSAPR Update. Id. at
74541. Thus, the EPA could not make an emissions reduction-based
conclusion that the CSAPR Update would fully resolve states' good
neighbor obligations with respect to the 2008 ozone NAAQS because the
reductions required by the CSAPR Update were EGU-only and because the
EPA focused the policy analysis for the CSAPR Update on reductions
available by the beginning of the 2017 ozone season.
    Finally, in promulgating the CSAPR Update, the EPA stated its
belief that it was beneficial to implement, without further delay, EGU
NOX reductions that were achievable in the near term,
particularly before the Moderate area attainment date of 2018.
Notwithstanding that additional reductions may be required to fully
address the states' interstate transport obligations, the EGU
NOX emissions reductions implemented by the final rule were
needed for upwind states to eliminate their significant contribution to
nonattainment or interference with maintenance of the 2008 ozone NAAQS
and to assist downwind states with ozone nonattainment areas that are
required to attain the standard by July 20, 2018.
    As a result of the remaining air quality problems and the
limitations on the EPA's analysis, for all but one of the 21 states at
issue, the EPA did not determine in the CSAPR Update that the CSAPR
Update fully addressed those states' downwind air quality impacts under
the good neighbor provision for the 2008 ozone NAAQS. Id. at 74521. For
one state, Tennessee, the EPA determined in the final CSAPR Update that
Tennessee's emissions budget fully eliminated the state's significant
contribution to downwind nonattainment and interference with
maintenance of the 2008 ozone NAAQS because the downwind air quality
problems to which the state was linked were projected to be resolved
with implementation of the CSAPR Update. Id. at 74552.

III. Proposed Determination Regarding Good Neighbor Obligations for the
2008 Ozone NAAQS

    As described in section II.D, in the CSAPR Update the EPA
promulgated FIPs intended to address the good neighbor provision for
the 2008 ozone NAAQS, but could not at that time determine that those
FIPs fully address 2008 ozone NAAQS good neighbor obligations for 21 of
the 22 CSAPR Update states, based on information available when the
rule was finalized. As a result, the CSAPR Update did not fully satisfy
the EPA's obligation to issue FIPs or approve SIPs to address those
states' good neighbor obligations for the 2008 ozone NAAQS. In this
notice, the EPA proposes to determine that, based on additional
information and analysis, the CSAPR Update fully addresses 20 of these
states' good neighbor obligations for the 2008 ozone NAAQS. In
particular, the EPA proposes to determine that there will be no
remaining nonattainment or maintenance receptors in the eastern U.S. in
2023. Therefore, after the CSAPR Update is implemented, these states
are not expected to contribute significantly to nonattainment in, or
interfere with maintenance by, any other state with regard to the 2008
ozone NAAQS. The obligation as to the remaining state (Kentucky) is
currently being addressed in a separate action.

A. Analytic Approach

    The Agency is evaluating its determination regarding CSAPR Update
states' remaining good neighbor obligations for the 2008 ozone NAAQS by
applying the same approach used in previous federal actions addressing
regional interstate transport of ozone pollution, including the CSAPR
Update which addressed the same NAAQS at issue in this rulemaking. Each
of these rulemakings followed the same four-step interstate transport
framework to quantify and implement emissions reductions necessary to
address the interstate transport requirements of the good neighbor
provision.\44\ These steps are summarized in the following four
paragraphs.
---------------------------------------------------------------------------

    \44\ With respect to the 2015 ozone NAAQS, the EPA recently
provided information to states to inform their development of SIPs
to address CAA section 110(a)(2)(D)(i)(I). In a memorandum dated
March 27, 2018, the Agency noted that, in developing their own
rules, states have flexibility to follow the familiar 4-step
transport framework (using the EPA's analytical approach or somewhat
different analytical approaches within these steps) or alternative
frameworks, so long as their chosen approach has adequate technical
justification and is consistent with the requirements of the CAA.
---------------------------------------------------------------------------

    Step 1: Identify downwind air quality problems relative to the 2008
ozone NAAQS. The EPA has historically identified downwind receptors
with air quality problems using air quality modeling projections and,
where appropriate, considering monitored ozone data for a future
compliance year. In the CSAPR Update, the agency relied on modeled and
monitored data to identify not only those receptors expected to be in
nonattainment with the ozone NAAQS, but also those receptors that may
have difficulty maintaining the NAAQS, notwithstanding clean monitored
data or projected attainment.
    Step 2: Determine which upwind states are ``linked'' to these
identified downwind air quality problems and thereby warrant further
analysis to determine whether their emissions violate the good neighbor
provision. In the CSAPR Update, the EPA identified such upwind states
as those modeled to contribute to a downwind receptor at or above an
air quality threshold equivalent to one percent of the 2008 ozone
NAAQS.
    Step 3: For states linked to downwind air quality problems,
identify upwind emissions on a statewide basis that significantly
contribute to nonattainment or interfere with maintenance of a standard
in any area. In all of the EPA's prior rulemakings addressing
interstate ozone pollution transport, the Agency identified and
apportioned emissions reduction responsibility among multiple upwind
states linked to downwind air quality problems by considering feasible
NOX control strategies and using cost-based and air quality-
based criteria to evaluate regionally uniform NOX control
strategies that were then used to quantify the amount of a linked
upwind state's emissions, if any, that significantly contribute to
nonattainment or interfere with maintenance in another state.

    Step 4: For upwind states that are found to have emissions that
significantly contribute to nonattainment or interfere with maintenance
of the NAAQS downwind, implement the necessary emissions reductions
within the state. In the CSAPR Update, the EPA implemented the
necessary emissions reductions from upwind states found to have good
neighbor obligations by requiring EGUs in those states to participate
in the CSAPR NOX Ozone Season Group 2 Trading Program, which
is very similar to the allowance trading programs used to implement the
emissions reductions quantified in the original CSAPR and other earlier
rules.\45\
---------------------------------------------------------------------------

    \45\ Affected sources have participated in EPA-administered
allowance trading programs under both SIPs and FIPs.
---------------------------------------------------------------------------

    Because this action is evaluating outstanding obligations that
remain with respect to the 2008 ozone NAAQS, the EPA believes it is
reasonable to apply the same framework used in the CSAPR Update in this
proposed action.
    Within this four-step interstate transport framework, the EPA only
proceeds to step four, in which it requires sources in upwind states to
implement enforceable emissions limitations, if: (1) Downwind air
quality problems are identified in at step 1; (2) an upwind state is
linked to a downwind air quality problem at step 2; and (3) sources in
the linked upwind state are identified as having emissions that
significantly contribute to nonattainment and interfere with
maintenance of the NAAQS considering cost- and air-quality-based
factors. For the reasons described in the following paragraphs, the EPA
believes this approach is a reasonable interpretation of the good
neighbor provision.
    The good neighbor provision instructs the EPA and states to apply
its requirements ``consistent with the provisions of'' title I of the
CAA. The EPA is therefore interpreting the requirements of the good
neighbor provision, and the elements of its four-step interstate
transport framework, to apply in a manner consistent with the
designation and planning requirements in title I that apply in downwind
states. See North Carolina, 531 F.3d at 912 (holding that the good
neighbor provision's reference to title I requires consideration of
both procedural and substantive provisions in title I). The EPA notes
that this consistency instruction follows the requirement that plans
``contain adequate provisions prohibiting'' certain emissions in the
good neighbor provision. The following paragraphs will therefore
explain how the EPA's interpretation of the circumstances under which
the good neighbor provision requires that plans ``prohibit'' emissions
through enforceable measures is consistent with the circumstances under
which downwind states are required to implement emissions control
measures in nonattainment areas.
    For purposes of this analysis, the EPA notes specific aspects of
the title I designations process and attainment planning requirements
for the ozone NAAQS that provide particularly relevant context for
evaluating the consistency of the EPA's approach to the good neighbor
provision in upwind states. The EPA notes that this discussion is not
intended to suggest that the specific requirements of designations and
attainment planning apply to upwind states pursuant to the good
neighbor provision, but rather to explain why the EPA's approach to
interpreting the good neighbor approach is reasonable in light of
relevant, comparable provisions found elsewhere in title I. In
particular, these provisions demonstrate that the EPA's approach is
consistent with other relevant provisions of title I with respect to
what data is considered in the EPA's analysis and when states are
required to implement enforceable measures.
    First, areas are initially designated attainment or nonattainment
for the ozone NAAQS based on actual measured ozone concentrations. CAA
section 107(d) (noting that an area shall be designated attainment
where it ``meets'' the NAAQS and nonattainment where it ``does not
meet'' the NAAQS). Therefore, a designation of nonattainment does not
in the first instance depend on what specific factors have influenced
the measured ozone concentrations or whether such levels are due to
enforceable emissions limits. If an area measures a violation of the
relevant ozone NAAQS, then the area is designated nonattainment. In
cases where the ozone nonattainment area is classified as Moderate or
higher, the responsible state is required to develop an attainment
plan, which generally includes the application of various enforceable
control measures to sources of emissions located in the nonattainment
area, consistent with the requirements in Part D of title I of the
Act.\46\ See generally CAA section 182, 42 U.S.C. 7511a. If, however,
an area measures compliance with the ozone NAAQS, the area is
designated attainment, and sources in that area generally are not
subject to any new enforceable control measures under Part D.\47\
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    \46\ Areas classified as Marginal nonattainment areas are
required to submit emissions inventories and implement a
nonattainment new source review permitting program, but are not
generally required to implement controls at existing sources. See
CAA section 182(a), 42 U.S.C. 7511a(a).
    \47\ Clean Air Act section 184 contains the exception to this
general rule: states that are part of the Ozone Transport Region are
required to provide SIPs that include specific enforceable control
measures, similar to those for nonattainment areas, that apply to
the whole state, even for areas designated attainment for the ozone
NAAQS. See generally 42 U.S.C. 7511c.
---------------------------------------------------------------------------

    Similarly, in determining the boundaries of an ozone nonattainment
area, the CAA requires the EPA to consider whether ``nearby'' areas
``contribute'' to ambient air quality in the area that does not meet
the NAAQS. 42 U.S.C. 7407(d). For each monitor or group of monitors
indicating a violation of the ozone NAAQS, the EPA assesses information
related to five factors, including current emissions and emissions-
related data from the areas near the monitor(s), for the purpose of
establishing the appropriate geographic boundaries for the designated
ozone nonattainment areas. A nearby area may be included within the
boundary of the ozone nonattainment area only after assessing area-
specific information, including an assessment of whether current
emissions from that area contribute to the air quality problem
identified at the violating monitor.\48\ If such a determination is
made, sources in the nearby area are also subject to the applicable
Part D control requirements. However, if the EPA determines that the
nearby area does not contribute to the measured nonattainment problem,
then the nearby area is not part of the designated nonattainment area
and sources in that area are not subject to such nonattainment control
requirements.
---------------------------------------------------------------------------

    \48\ See Attachment 2 to Area Designations for the 2008 Ozone
National Ambient Air Quality Standards. Memorandum from Robert J.
Meyers, Principal Deputy Assistant Administrator, US EPA to Regional
Administrators. December 4, 2008. Available at https://archive.epa.gov/ozonedesignations/web/pdf/area_designations_for_the_2008_revised_ozone_naaqs.pdf.
---------------------------------------------------------------------------

    The EPA's historical approach to addressing the good neighbor
provision via the four-step interstate transport framework, and the
approach the EPA proposes to continue to apply here, is consistent with
these title I requirements. That is, in steps 1 and 2 of the framework,
the EPA evaluates whether there is a downwind air quality problem
(either nonattainment or maintenance), and whether an upwind state
impacts the downwind area such that it contributes to and is therefore
``linked'' to the downwind area. The EPA's determination at step 1 of
the good neighbor analysis that it has not

identified any downwind air quality problems to which an upwind state
could contribute is analogous to the EPA's determination in the
designation analysis that an area should be designated attainment.
Similarly, EPA's determination at step 2 of the good neighbor analysis
that, while it has at step 1 identified downwind air quality problems,
an upwind state does not sufficiently impact the downwind area such
that the state is ``linked,'' is analogous to the EPA's determination
in the designation analysis that a nearby area does not contribute to a
NAAQS violation in another area. Thus, under the good neighbor
provision, the EPA determines at step 1 or 2, as appropriate, that the
upwind state will not significantly contribute to nonattainment or
interfere with maintenance in the downwind area. See, e.g., 81 FR 74506
(determining that emissions from 14 states do not significantly
contribute to nonattainment or interfere with maintenance of the 2008
ozone NAAQS); 76 FR 48236 (finding that states whose contributions to
downwind receptors are below the air quality threshold do not
significantly contribute to nonattainment or interfere with maintenance
of the relevant NAAQS). Under such circumstances, sources in the upwind
state are not obligated to implement any control measures under the
good neighbor provision, which is consistent with the fact that sources
located in attainment areas generally are not required to implement the
control measures found in Part D of the Act. Cf. EME Homer City II, 795
F.3d at 130 (determining that CSAPR ozone-season NOX budgets
for 10 states were invalid based on determination that modeling showed
no future air quality problems); 81 FR 74523-24 (removing three states
from CSAPR ozone season NOX program based on determination
that states are not linked to any remaining air quality problems for
the 1997 ozone NAAQS).
    The EPA acknowledges one distinction between the good neighbor and
designation analyses: The good neighbor analysis relies on future-year
projections of emissions to calculate ozone concentrations and upwind
state contributions, compared to the designation analysis's use of
current measured data. As described in more detail later, this approach
is a reasonable interpretation of the term ``will'' in the good
neighbor provision, see North Carolina, 531 F.3d at 913-14, and
interpreting language specific to that provision does not create an
impermissible inconsistency with other provisions of title I. Moreover,
the EPA's use of future-year modeling in the good neighbor analysis to
identify downwind air quality problems and linked states is consistent
with its use of current measured data in the designations process. The
EPA's future-year air quality projections consider a variety of
factors, including current emissions data, anticipated future control
measures, economic market influences, and meteorology. Many of these
same factors, e.g., current control measures, economic market
influences, and meteorology, can affect the NOX emissions
levels and consequent measured ozone concentrations that inform the
designations process. Like the factors that affect measured ozone
concentrations used in the designations process, not all of the factors
influencing the EPA's modeling projections are or can be enforceable
limitations on emissions or ozone concentrations. However, the EPA
believes that consideration of these factors contributes to a
reasonable estimate of anticipated future ozone concentrations. See EME
Homer City II, 795 F.3d at 135 (declining to invalidate EPA's modeling
projections ``solely because there might be discrepancies between those
predictions and the real world''); Chemical Manufacturers Association
v. EPA, 28 F.3d 1259, 1264 (DC Cir. 1994) (``a model is meant to
simplify reality in order to make it tractable''). Thus, the EPA
believes that consideration of these factors in its future-year
modeling projections used at steps 1 and 2 of the good neighbor
analysis is reasonable and consistent with the use of measured data in
the designation analysis.\49\
---------------------------------------------------------------------------

    \49\ The EPA also notes that the consideration of projected
actual emissions in the future analytic year--as opposed to
allowable levels--is also consistent with the statute's instruction
that states (or EPA in the states' stead) prohibit emissions that
``will'' impermissibly impact downwind air quality. This term is
reasonably interpreted to mean that the EPA should evaluate
anticipated emissions (what sources will emit) rather than potential
emissions (what sources could emit).
---------------------------------------------------------------------------

    The EPA notes that there is a further distinction between the
section 107(d) designations provision and the good neighbor provision
in that the latter provision uses different terms to describe the
threshold for determining whether emissions in an upwind state should
be regulated (``contribute significantly'') as compared to the standard
for evaluating the impact of nearby areas in the designations process
(``contribute''). Thus, at step 3 of the good neighbor analysis the EPA
evaluates additional factors, including cost and air-quality
considerations, to determine whether emissions from a linked upwind
state do or would violate the good neighbor provision. Only if the EPA
at step 3 determines that the upwind state's emissions do or would
violate the good neighbor provision will it proceed to step 4, at which
point emissions in the upwind state must be controlled so as to address
the identified violation, analogous to the trigger for the application
of Part D requirements to sources located in designated nonattainment
areas. The EPA interprets the good neighbor provision to not require it
or the upwind state to proceed to step 4 and implement any enforceable
measures to ``prohibit'' emissions unless it identifies a violation of
the provision at step 3. See, e.g., 76 FR 48262 (finding at step 3 that
the District of Columbia is not violating the good neighbor provision,
and therefore will not at step 4 be subject to any control requirements
in CSAPR, because no cost-effective emissions reductions were
identified).

B. Selection of a Future Analytic Year

    In this action, consistent with historical practice, the EPA
focuses its analysis on a future year in light of the forward-looking
nature of the good neighbor obligation in section 110(a)(2)(D)(i)(I).
Specifically, the statute requires that states prohibit emissions that
``will'' significantly contribute to nonattainment or interfere with
maintenance of the NAAQS in any other state. The EPA reasonably
interprets this language as permitting states and the EPA in
implementing the good neighbor provision to prospectively evaluate
downwind air quality problems and the need for further upwind emissions
reductions. In the EPA's prior regional transport rulemakings, the
Agency generally evaluated whether upwind states ``will'' significantly
contribute to nonattainment or interfere with maintenance based on
projections of air quality in the future year in which any emissions
reductions would be expected to go into effect. Thus, when the EPA
finalized the NOX SIP Call in 1998, it used the anticipated
2007 full compliance year for its analysis, and when the EPA finalized
CAIR in 2005, it used the years 2009 and 2010, anticipated compliance
years for the 1997 ozone and 1997 PM2.5 NAAQS, respectively.
63 FR 57377; 70 FR 25241. The D.C. Circuit affirmed the EPA's
interpretation of ``will'' in CAIR, finding the EPA's consideration of
future projected air quality (in addition to current measured data) to
be a reasonable interpretation of an ambiguous term. North Carolina,
531 F.3d at 913-14. The EPA applied the same approach in finalizing
CSAPR in

2011 and the CSAPR Update in 2016 by evaluating air quality in 2012 and
2017, respectively. 76 FR 48211; 81 FR 74537. Thus, consistent with
this precedent, a key decision that informs the application of the
interstate transport framework is selecting a future analytic year. In
determining the appropriate future analytic year for purposes of
assessing remaining interstate transport obligations for the 2008 ozone
NAAQS, the EPA considered two primary factors: (1) The applicable
attainment dates; and (2) the timing to feasibly implement new
NOX control strategies, which are discussed in the following
two sections. The EPA proposes to determine that these factors
collectively support the use of 2023 as the future analytic year for
this proposed action.
1. Attainment Dates for the 2008 Ozone NAAQS
    First, the EPA considers the downwind attainment dates for the 2008
ozone NAAQS. In North Carolina, the D.C. Circuit held that emissions
reductions required by the good neighbor provision should be evaluated
considering the relevant attainment dates of downwind nonattainment
areas impacted by interstate transport. 531 F.3d at 911-12 (holding
that the EPA must consider downwind attainment dates when establishing
interstate transport compliance deadlines). Many areas currently have
attainment dates of July 20, 2018 for areas classified as Moderate,
but, as noted earlier, the 2017 ozone season was the last full season
from which data could be used to determine attainment of the NAAQS by
the July 20, 2018 attainment date. Given that the 2017 ozone season has
now passed, it is not possible to achieve additional emissions
reductions by the Moderate area attainment date. It is therefore
necessary to consider what subsequent attainment dates should inform
the EPA's analysis. The next attainment dates for the 2008 ozone NAAQS
will be July 20, 2021, for nonattainment areas classified as Serious,
and July 20, 2027, for nonattainment areas classified as Severe.\50\
Because the various attainment deadlines are in July, which is in the
middle of the ozone monitoring season for all states, data from the
calendar year prior to the attainment date (e.g., data from 2020 for
the 2021 attainment date and from 2026 for the 2027 attainment date)
are the last data that can be used to demonstrate attainment with the
NAAQS by the relevant attainment date. Therefore, the EPA considers the
control strategies that could be implemented by 2020 and 2026 in
assessing the 2021 and 2027 attainment dates in its subsequent
analysis. The EPA has also considered that, in all cases, the statute
provides that areas should attain as expeditiously as practicable.\51\
---------------------------------------------------------------------------

    \50\ While there are no areas (outside of California) that are
currently designated as Serious or Severe for the 2008 ozone NAAQS,
the CAA requires that the EPA reclassify to Serious any Moderate
nonattainment areas that fail to attain by their attainment date of
July 20, 2018. Similarly, if any area fails to attain by the Serious
area attainment date, the CAA requires that the EPA reclassify the
area to Severe.
    \51\ See CAA section 181(a)(1), 42 U.S.C. 7511(a)(1).
---------------------------------------------------------------------------

2. Feasibility of Control Strategies To Reduce Ozone Season
NOX
    Second, the EPA considers the timeframes that may be required to
implement further emissions reductions as expeditiously as practicable.
Generally, NOX emissions levels are expected to decline in
the future through the combination of the implementation of existing
local, state, and federal emissions reduction programs and changing
market conditions for generation technologies and fuels.\52\ This is an
important consideration because the U.S. Supreme Court and the D.C.
Circuit Court have both held that the EPA may not over-control: It may
not require emissions reductions (at step 3 of the good neighbor
framework) from a state that are greater than necessary to achieve
attainment and maintenance of the NAAQS in all of the downwind areas to
which that state is linked.\53\ In particular, in EME Homer City II,
the D.C. Circuit determined that the CSAPR phase 2 ozone-season
NOX budgets for ten states were invalid because EPA's
modeling showed that the downwind air quality problems to which these
states were linked would be resolved by 2014, when the phase 2 budgets
were scheduled to be implemented. 795 F.3d at 129-30. Therefore,
because new controls cannot be implemented feasibly for several years,
and at that later point in time air quality will likely be better due
to continued phase-in of existing regulatory programs, changing market
conditions, and fleet turnover, it is reasonable for the EPA to
evaluate air quality (at step 1 of the good neighbor framework) in a
future year that is aligned with feasible control installation timing
in order to ensure that the upwind states continue (at step 2) to be
linked to downwind air quality problems when any potential emissions
reductions (identified at step 3) would be implemented (at step 4) and
to ensure that such reductions do not over-control relative to the
identified ozone problem.
---------------------------------------------------------------------------

    \52\ Annual Energy Outlook 2018. Electricity Supply,
Disposition, Prices, and Emissions. Reference Case. Department of
Energy, Energy Information Administration. Available at https://www.eia.gov/outlooks/aeo/data/browser/#/?id=8-AEO2018&cases=ref2018&sourcekey=0.
    \53\ EPA v. EME Homer City Generation, L.P., 134 S. Ct. at 1600-
01; EME Homer City II, 795 F.3d at 127.
---------------------------------------------------------------------------

    The EPA's analysis of the feasibility of NOX control
strategies reflects the time needed to plan for, install, test, and
place into operation new EGU and non-EGU NOX reduction
strategies regionally--i.e., across multiple states. This regional
analytic approach is consistent with the regional nature of interstate
ozone pollution transport as described in section II.A. The Agency
adopted this approach for this proposal based on previous interstate
ozone transport analyses showing that where eastern downwind ozone
problems are identified, multiple upwind states typically are linked to
these problems.\54\ Specifically of relevance to this action, as
discussed in section II.C, the EPA's assessment of CSAPR Update
implementation found that 21 states continued to contribute greater
than or equal to 1% of the 2008 ozone NAAQS to identified downwind
nonattainment or maintenance receptors in multiple downwind states in
2017. Thus, to reasonably address these ozone transport problems, the
EPA must identify and apportion emissions reduction responsibility
across multiple upwind states. In other words, the EPA's analysis
should necessarily be regional, rather than focused on individual
linkages. Where such an analysis is needed for multiple states, the
inquiry into the availability and feasibility of control options is
necessarily considerably more complicated than for a single state or
sector.
---------------------------------------------------------------------------

    \54\ 81 FR 74538.
---------------------------------------------------------------------------

    Further, the feasibility of new emissions controls should be
considered with regard to multiple upwind source categories to ensure
that the Agency properly evaluates NOX reduction potential
and cost-effectiveness from all reasonable control measures (including
those that are or may be available outside of the EGU sector).
NOX emissions come from multiple anthropogenic source
categories, such as mobile sources, electric utilities, resource
extraction industries, and industrial and commercial facilities. As
noted in section II.A, the EPA has historically addressed mobile source
emissions through national rulemakings. Moreover, mobile source
emissions are already decreasing

because of sector[hyphen]specific standards related to fuels, vehicle
fuel economy, pollution controls, and repair and replacement of the
existing fleet. Programs such as the Tier 3 vehicle emissions standards
are already being phased in between now and 2023. That rule was
finalized in 2014 with a phase-in schedule of 2017-2025 reflecting
fleet turnover. Thus, another reason that in this proposed action the
EPA has focused on stationary sources is that emissions reductions from
those sources could likely be implemented more quickly than would
result from any attempt to effect additional reductions from mobile
sources beyond those described.
    Among stationary sources, EGUs in the eastern U.S. have been the
primary subject of regulation to address interstate ozone pollution
transport and have made significant financial investments to achieve
emissions reductions. While the EPA continues to evaluate control
feasibility for EGUs in its analysis, the EPA's recent analyses
indicate that non-EGU source categories, which the EPA has not made
subject to new regulations to address interstate ozone transport since
the NOX SIP Call, may also be well-positioned to cost-
effectively reduce NOX relative to EGUs.\55\ Accordingly,
the EPA's assessment of control feasibility focuses on both EGU and
non-EGU sources.
---------------------------------------------------------------------------

    \55\ See Assessment of Non-EGU NOX Emission Controls,
Cost of Controls, and Time for Compliance Final TSD from the CSAPR
Update in the docket for this rulemaking.
---------------------------------------------------------------------------

a. EGUs
    First, the EPA presents its feasibility assessment of
NOX control strategies for EGUs. In establishing the CSAPR
Update EGU ozone season NOX emissions budgets, the Agency
quantified the emissions reductions achievable from all NOX
control strategies that were feasible to implement in less than one
year and cost-effective at a marginal cost of $1,400 per ton of
NOX removed.\56\ These EGU NOX control strategies
were: optimizing NOX removal by existing, operational
selective catalytic reduction (SCR) controls; turning on and optimizing
existing idled SCR controls; installing state-of-the-art NOX
combustion controls; and shifting generation to existing units with
lower-NOX emissions rates within the same state. 81 FR
74541. The Agency believes that the resulting CSAPR Update emissions
budgets are being appropriately implemented under the CSAPR
NOX Ozone Season Group 2 allowance trading program.
Preliminary data for the 2017 ozone season (the first CSAPR Update
compliance period) indicate that power plant ozone season
NOX emissions across the 22 state CSAPR Update region were
reduced by 77,420 tons (or 21%) from 2016 to 2017.\57\ As a result,
total 2017 ozone season NOX emissions from covered EGUs
across the 22 CSAPR Update states were approximately 294,478 tons,\58\
well below the sum of states' emissions budgets established in the
CSAPR Update of 316,464 tons. Accordingly, for the purposes of this
proposed determination, the EPA considers the turning on and optimizing
of existing SCR controls and the installation of combustion controls to
be NOX control strategies that have already been
appropriately evaluated and implemented in the final CSAPR Update.
---------------------------------------------------------------------------

    \56\ The CSAPR Update was signed on September 7, 2016--
approximately 8 months before the beginning of the 2017 ozone season
on May 1.
    \57\ https://ampd.epa.gov/ampd/ (Data current as of March 1,
2018).
    \58\ Id.
---------------------------------------------------------------------------

    In the CSAPR Update, the EPA also identified one EGU NOX
control strategy that was considered feasible to implement within one
year but was not cost-effective at a marginal cost of $1,400 per ton of
NOX removed: specifically, turning on existing idled
selective non-catalytic reduction (SNCR) controls. In the CSAPR Update,
the EPA identified a marginal cost of $3,400 per ton as the level of
uniform control stringency that represents turning on and fully
operating idled SNCR controls.\59\ However, the CSAPR Update finalized
emissions budgets using $1,400 per ton control stringency, finding that
this level of stringency represented the control level at which
incremental EGU NOX reductions and corresponding downwind
ozone air quality improvements were maximized with respect to marginal
cost. In finding that use of the $1,400 control cost level was
appropriate, the EPA established that the more stringent emissions
budget level reflecting $3,400 per ton (representing turning on idled
SNCR controls) yielded fewer additional emissions reductions and fewer
air quality improvements relative to the increase in control costs. In
other words, based on the CSAPR Update analysis, establishing emissions
budgets at $3,400 per ton, and therefore developing budgets based on
operation of idled SNCR controls, was not determined to be cost-
effective for addressing good neighbor provision obligations for the
2008 ozone NAAQS. 81 FR 74550. The EPA believes that the strategy of
turning on and fully operating idled SNCR controls was appropriately
evaluated in the CSAPR Update with respect to addressing interstate
ozone pollution transport for the 2008 ozone NAAQS. Accordingly, in
this proposal the EPA is not further assessing this control strategy
for purposes of identifying an appropriate future analytic year.
---------------------------------------------------------------------------

    \59\ See EGU NOX Mitigation Strategies Final Rule TSD
(docket ID EPA-HQ-OAR-2015-0500-0554, available at
www.regulations.gov and https://www.epa.gov/sites/production/files/2017-05/documents/egu_nox_mitigation_strategies_final_rule_tsd.pdf)
(NOX Mitigation Strategies TSD).
---------------------------------------------------------------------------

    As mentioned previously, the EPA evaluated shifting generation from
EGUs with higher NOX-emissions rates to EGUs with lower
NOX-emissions rates as a means of reducing emissions in the
context of the CSAPR Update. Shifting generation is a NOX
control strategy that occurs on a time- and cost-continuum, in contrast
to the relatively discrete price-points and installation timeframes
that can be identified for combustion and post-combustion controls.
Therefore, in the CSAPR Update, the EPA identified the discrete cost
thresholds used to evaluate upwind states' good neighbor obligations
based on its evaluation of combustion and post-combustion controls, and
secondarily examined the amount of generation shifting that would
result at the same cost threshold associated with the particular
control technology. Quantifying NOX reductions from shifting
generation anticipated at the same cost thresholds relative to the
control technologies being considered (e.g., restarting idled SCR
controls) helped ensure that the emissions reductions associated with
the control strategies could be expected to occur. In other words, had
the agency excluded consideration of generation shifting in calculating
emissions budgets, generation shifting would have nonetheless occurred
as a compliance strategy, but the consequence would have been a smaller
amount of emissions reduction than what the agency knew to be
achievable and cost[hyphen]effective at the selected cost threshold.
Thus, although potential emissions reductions resulting from generation
shifting were factored into the final budgets, this compliance strategy
did not drive the EPA's identification of cost thresholds analyzed in
the rule.
    For the same reasons, the EPA does not find it appropriate to
evaluate generation shifting, in isolation from viable combustion or
post-combustion control assessments, for purposes of selecting a future
analytic year. If the EPA were to choose an earlier analytic year based
on the ability of upwind sources to implement some level of

generation shifting within that timeframe, before other specific
control technologies could be implemented, this would have the
consequence of limiting the EPA's analysis and the amount of emissions
reductions that would be considered cost-effective and therefore
subject to regulation under the good neighbor provision, relative to a
more robust analysis that considers other emissions controls available
within defined timeframes. Further, due to continued lower cost natural
gas prices and price projections, significant shifting from higher
emitting coal sources to lower emitting gas sources (relative to
historical generation levels) is occurring and expected to continue to
occur by 2023 due to market drivers. Thus, there may be limited
opportunity for the sources to implement further emissions reductions
through generation shifting over the next 5 years. Given the
indeterminate implementation timeframes for generation shifting and the
EPA's historical consideration of this strategy as a secondary factor
in quantifying emissions budgets, the EPA believes the most reasonable
approach for selecting a future analytic year is to focus on the
timeframe in which specific control technologies other than generation
shifting can be implemented.\60\
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    \60\ Because the EPA is not in this proposal evaluating
additional generation shifting possibilities, it does not at this
time need to revisit the question whether it is within the EPA's
authority or otherwise proper to consider generation shifting in
implementing the good neighbor provision. The EPA is aware that this
has been an issue of contention in the past, and stakeholders have
raised serious concerns regarding this issue. See, e.g., 81 FR at
74545 (responding to comments); CSAPR Update Rule--Response to
Comment, at 534-50 (EPA-HQ-OAR-2015-0500-0572) (summarizing and
responding to comments). The EPA may revisit this question in
addressing good neighbor requirements for other NAAQS but is not
soliciting comment at this time on this issue with regard to the
2008 ozone NAAQS.
---------------------------------------------------------------------------

    For these reasons, for purposes of identifying an appropriate
future analytic year, the EPA is focusing its assessment of EGUs in
this action on controls that were deemed to be infeasible to install
for the 2017 ozone season rather than reassessing controls previously
analyzed for cost-effective emissions reductions in the CSAPR Update.
In establishing the CSAPR Update emissions budgets, the EPA identified
but did not analyze the following two EGU NOX control
strategies in establishing the CSAPR Update emissions budgets because
implementation by 2017 was not considered feasible: (1) Installing new
SCR controls; and (2) installing new SNCR controls. In the CSAPR
Update, EPA observed that EGU SCR post-combustion controls can achieve
up to 90 percent reduction in EGU NOX emissions. In 2017,
these controls were in widespread use by EGUs in the east. EPA also
observed that SNCR controls can be effective at reducing NOX
emissions and can achieve up to a 25 percent emissions reduction from
EGUs (with sufficient reagent). In 2017, these controls were also used
across the power sector. In the 22-state CSAPR Update region,
approximately 62 percent of coal-fired EGU capacity is equipped with
SCR controls and 12 percent is equipped with SNCR controls.\61\
---------------------------------------------------------------------------

    \61\ National Electric Energy Data System v6 (NEEDS). EPA.
Available at https://www.epa.gov/airmarkets/national-electric-energy-data-system-needs-v6.
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    Installing new SCR or SNCR controls for EGUs generally involves the
following steps: conducting an engineering review of the facility;
advertising and awarding a procurement contract; obtaining a
construction permit; installing the control technology; testing the
control technology; and obtaining or modifying an operating permit.\62\
Because installing these post-combustion controls--SCR or SNCR--involve
the same steps and many of the same considerations, the timing of their
feasible regional development is described together in the following
paragraphs. However, the EPA notes differences between these control
technologies with respect to the potential viability of achieving cost-
effective regional NOX reductions from EGUs. As described
above, SCR controls generally achieve greater EGU NOX
reduction efficiency (up to 90%) than SNCR controls (up to 25%).
Resulting in part from this disparity in NOX reduction
efficiency, when considering both control costs and NOX
reduction potential in developing cost per ton analysis for the CSAPR
Update, the EPA found new SCR controls to be more cost-effective at
removing NOX. Specifically, the EPA found that new SCR
controls could generally reduce EGU emissions for $5,000 per ton of
NOX removed whereas new SNCR controls could generally reduce
EGU emissions at a higher cost of $6,400 per ton of NOX
removed.\63\ In other words, the greater NOX reduction
efficiency for SCR controls translates into greater cost-effectiveness
relative to SNCR controls. The general cost-effectiveness advantage is
consistent with observed installation patterns where SCR controls (62%
of coal-fired capacity) are more prevalent across the east relative to
SNCR (12% of coal-fired capacity).
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    \62\ Final Report: Engineering and Economic Factors Affecting
the Installation of Control Technologies for Multipollutant
Strategies, EPA-600/R-02/073 (Oct. 2002), available at https://nepis.epa.gov/Adobe/PDF/P1001G0O.pdf.
    \63\ NOX Mitigation Strategies TSD.
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    For SCR, the total time associated with navigating necessary steps
is estimated to be up to 39 months for an individual power plant
installing SCR on more than one boiler.\64\ However, more time is
needed when considering installation timing for new SCR controls across
the Eastern EGU fleet addressed in this action. As described in the
subsequent paragraphs, EPA determined that a minimum of 48 months is a
reasonable time period to allow for the coordination of outages,
shepherding of labor and material supply, and identification of
retrofit projects. This timeframe would facilitate multiple power
plants with multiple boilers to conduct all stages of post-combustion
and combustion control project planning, installation, and operation.
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    \64\ Engineering and Economic Factors Affecting the Installation
of Control Technologies for Multipollutant Strategies. EPA Final
Report. Table 3-1. Available at https://archive.epa.gov/clearskies/web/pdf/multi102902.pdf.
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    Scheduled curtailment, or planned outage, for pollution control
installation would be necessary to complete either SCR or SNCR
projects. Given that peak demand and rule compliance would both fall in
the ozone season, sources would likely try to schedule installation
projects for the ``shoulder'' seasons (i.e., the spring and/or fall
seasons), when electricity demand is lower than in the summer, reserves
are higher, and ozone season compliance requirements are not in effect.
If multiple units were under the same timeline to complete the retrofit
projects as soon as feasible from an engineering perspective, this
could lead to bottlenecks of scheduled outages as each unit attempts to
start and finish its installation in roughly the same compressed time
period. Thus, any compliance timeframe that would assume installation
of new SCR or SNCR controls should encompass multiple shoulder seasons
to accommodate scheduling of curtailment for control installation
purposes and better accommodate the regional nature of the program.
    In addition to the coordination of scheduled curtailment, an
appropriate compliance timeframe should accommodate the additional
coordination of labor and material supply necessary for any fleet-wide
mitigation efforts. The total construction labor for a SCR system
associated with a 500-megawatt (MW) EGU is in the range of 300,000 to
500,000 man-hours, with boilermakers accounting for

approximately half of this time.\65\ SNCR installations, while
generally having shorter individual project timeframes of 10 to 13
months from bid solicitation to startup, share similar labor and
material resources and the timing of SNCR installation planning is
therefore linked to the timing of SCR installation planning. In recent
industry surveys, one of the largest shortages of union craft workers
was for boilermakers. This shortage of skilled boilermakers is expected
to rise due to an anticipated nine percent increase in boilermaker
labor demand growth by 2026, coupled with expected retirements and
comparatively low numbers of apprentices joining the workforce.\66\ The
shortage of and demand for skilled labor, including other craft workers
critical to pollution control installation, is pronounced in the
manufacturing industry. The Association of Union Constructors conducted
a survey of identified labor shortages and found that boilermakers were
the second-most frequently reported skilled labor market with a labor
shortage.\67\ Moreover, recovery efforts from the natural disasters of
Hurricanes Harvey and Irma and wildfires in 2017 are expected to
further tighten the labor supply market in manufacturing in the near
term.\68\ The EPA determined that these tight labor market conditions
within the relevant manufacturing sectors, combined with fleet-level
mitigation initiatives, would likely lead to some sequencing and
staging of labor pool usage, rather than simultaneous construction
across all efforts. This sector-wide trend supports SCR and SNCR
installation timeframes for a fleet-wide program that exceeds the
demonstrated single-unit installation timeframe.
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    \65\ Id.
    \66\ Occupational Outlook Handbook. Bureau of Labor Statistics.
Available at https://www.bls.gov/ooh/construction-and-extraction/boilermakers.htm.
    \67\ Union Craft Labor Supply Survey. The Association of Union
Constructors. Exhibit 4-2 at page 29. Available at https://www.tauc.org/files/2017_TAUC_UNION_CRAFT_LABOR_SUPPLY_REVISEDBC_FINAL.pdf.
    \68\ Skilled Wage Growth Less Robust, Worker Shortage Still an
Issue. Industry Week. October 23, 2017. Available at http://www.industryweek.com/talent/skilled-wage-growth-less-robust-worker-shortage-still-issue.
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    In addition to labor supply, NOX post-combustion control
projects also require materials and equipment such as steel and cranes.
Sheet metal workers, necessary for steel production, are also reported
as having well above an average supply-side shortage of labor.\69\
This, coupled with growth in steel demand estimated at three percent in
2018 suggests that there may be a constricted supply of steel needed
for installation of new post-combustion controls.\70\ Similarly, cranes
are critical for installation of SCRs, components of which must be
lifted hundreds of feet in the air during construction. Cranes are also
facing higher demand during this period of economic growth, with
companies reporting a shortage in both equipment and
manpower.71 72 The tightening markets in relevant skilled
labor, materials, and equipment, combined with the large number of
installations that could be required fleet-wide under a regional air
pollution transport program, necessitates longer installation time-
tables relative to what has been historically demonstrated at the unit-
level.
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    \69\ Union Craft Labor Supply Survey. The Association of Union
Constructors. Exhibit 4-2 at page 29. Available at https://www.tauc.org/files/2017_TAUC_UNION_CRAFT_LABOR_SUPPLY_REVISEDBC_FINAL.pdf.
    \70\ Worldsteel Short Range Outlook. October 16, 2017. Available
at https://www.worldsteel.org/media-centre/press-releases/2017/worldsteel-Short-Range-Outlook-2017-2018.html.
    \71\ See, e.g., Seattle Has Most Cranes in the Country for 2nd
Year in a Row--and Lead is Growing. Seattle Times. July 11, 2017.
Available at https://www.seattletimes.com/business/real-estate/seattle-has-most-cranes-in-the-country-for-2nd-year-in-a-row-and-lead-is-growing/.
    \72\ See RLB Crane Index, January 2018 in the docket for this
action.
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    The time lag observed between the planning phase and in-service
date of SCR operations in certain cases also illustrates that site-
specific conditions sometimes lead to installation times of four years
or longer. For instance, SCR projects for units at the Ottumwa power
plant (Iowa), Columbia power plant (Wisconsin), and Oakley power plant
(California) were all in the planning phase in 2014. By 2016, these
projects were under construction with estimated in-service dates of
2018.\73\ Similarly, individual SNCR projects can exceed their
estimated 10 through 13-month construction time frame. For example,
projects such as SNCR installation at the Jeffrey power plant (Kansas)
were in the planning phase in 2013, but not in service until 2015.\74\
Completed projects, when large in scale, also illustrate how timelines
can extend beyond the bare minimum necessary for a single unit when the
project is part of a larger air quality initiative involving more than
one unit at a plant. For instance, the Big Bend Power Station in
Florida completed a multi-faceted project that involved adding SCRs to
all four units as well as converting furnaces, over-fire air changes,
and making windbox modifications. The time from the initial planning
stages to completion was a decade.\75\
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    \73\ 2014 EIA Form 860. Schedule 6. Environmental Control
Equipment.
    \74\ 2013 EIA Form 860, Schedule 6, Environmental Control
Equipment.
    \75\ Big Bend's Multi-Unit SCR Retrofit. Power Magazine. March
1, 2010. Available at http://www.powermag.com/big-bends-multi-unit-scr-retrofit/.
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    While individual unit-level SCR and SNCR projects can average 39
and 10 months, respectively, from bid to startup, a comprehensive and
regional emissions reduction effort also requires more time to
accommodate the labor, materials, and outage coordination for these two
types of control strategies. Because these post-combustion control
strategies share similar resource inputs and are part of regional
emissions reduction programs rather than unit-specific technology
mandates, the timeframes for one type are inherently linked to the
other type. This means that SNCR projects cannot be put on an early
schedule in light of their reduced construction timing without
impacting the availability of resources for the manufacture and
installation of SCRs and thus the potential start dates of those
projects.
    In short, given the market and regulatory circumstances in which
EPA evaluated this effort, our analysis shows that four years would be
an expeditious timeframe to coordinate the planning and completion of
any mitigation efforts necessary in this instance.
b. Non-EGU Control Technologies
    The EPA is also evaluating the feasibility of implementing
NOX control technologies for non-EGUs in its assessment of
an appropriate future analytic year. While the EPA did not regulate
non-EGUs in the CSAPR Update, the rule did evaluate the feasibility of
NOX controls on non-EGUs in the eastern United States to
assess whether any such controls could be implemented in time for the
2017 ozone season. The EPA noted that there was greater uncertainty in
the assessment of non-EGU point-source NOX mitigation
potential as compared to EGUs, and therefore explained that more time
was required for states and the EPA to improve non-EGU point source
data, including data on existing control efficiencies, additional
applicable pollution control technologies, and installation times for
those control technologies. 81 FR 74542. A significant factor
influencing uncertainty was that the EPA lacked sufficient information
on the capacity and experience of suppliers and major engineering
firms' supply chains to determine if they would be able to install the
required pollution controls for non-EGU sources

in time for the 2017 ozone season. Further, using the best information
available to the EPA at that time, the EPA found that there were more
non-EGU point sources than EGU sources and that these sources on
average emit less NOX than EGUs. The implication was that
there were more individual sources that could be controlled, but
relatively fewer emissions reductions available from each source when
compared to the number of EGUs and emissions reductions available from
EGUs. Considering these factors, the EPA found that it was
substantially uncertain whether significant aggregate NOX
mitigation would be achievable from non-EGU point sources to address
the 2008 ozone NAAQS by the 2017 ozone season. Id.
    Although the EPA determined that there were limited achievable
emissions reductions available from non-EGUs by the 2017 ozone season,
the EPA acknowledged that it may be appropriate to evaluate potential
non-EGU emissions reductions achievable on a timeframe after the 2017
ozone season to assess upwind states' full good neighbor obligation for
the 2008 ozone NAAQS. 81 FR 74522. In particular, the EPA's preliminary
assessment indicated that there may be emissions reductions achievable
from non-EGUs at marginal costs lower than the costs of remaining
NOX control strategies available for EGUs. Accordingly, in
assessing an appropriate future analytic year, the EPA is also
considering the potential implementation timeframes for NOX
emissions reductions available for non-EGUs. In evaluating potential
non-EGU emissions reductions in the CSAPR Update, the EPA included
preliminary estimates of installation times for some non-EGU
NOX control technologies in a technical support document
entitled Assessment of Non-EGU NOX Emission Controls, Cost
of Controls, and Time for Compliance Final Technical Support Document
(henceforth, ``Final Non-EGU TSD''). These preliminary estimates were
based on research from a variety of information sources, including:

     Typical Installation Timelines for NOX Emissions
Control Technologies on Industrial Sources, Institute of Clean Air
Companies, December 2006 (all sources except cement kilns and
reciprocating internal combustion engines (RICE)); \76\
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    \76\ Institute of Clean Air Companies. Typical Installation
Timelines for NOX Emissions Control Technologies on
Industrial Sources, December 2006. Available at https://c.ymcdn.com/sites/icac.site-ym.com/resource/resmgr/ICAC_NOx_Control_Installatio.pdf.
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     Cement Kilns Technical Support Document for the NOX
FIP, US EPA, January 2001; \77\ and
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    \77\ US EPA. Cement Kilns Technical Support Document for the
NOX FIP. January 2001. Available at https://www.regulations.gov/document?D=EPA-HQ-OAR-2015-0500-0094.
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     Availability and Limitations of NOX Emission Control
Resources for Natural Gas-Fired Reciprocating Engine Prime Movers
Used in the Interstate Natural Gas Transmission Industry, Innovative
Environmental Solutions Inc., July 2014 (prepared for the INGAA
Foundation).\78\
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    \78\ INGAA Foundation. Availability and Limitations of
NOX Emission Control Resources for Natural Gas-Fired
Reciprocating Engine Prime Movers Used in the Interstate Natural Gas
Transmission Industry, Innovative Environmental Solutions Inc., July
2014. Available at http://www.ingaa.org/Foundation/Foundation-Reports/NOX.aspx.

The EPA's analysis in the Final Non-EGU TSD focused on potential
control technologies within the range of costs considered in the final
CSAPR Update for EGUs, or those controls available at a marginal cost
of $3,400 per ton (2011 dollars) of NOX reduced or less. The
EPA's analysis did not evaluate implementation timeframes or potential
emissions reductions available from controls at higher cost thresholds.
See Final Non-EGU TSD at 18. This focus excluded some emissions source
groups with emissions reduction potential at a marginal cost greater
than $3,400 per ton, including: industrial/commercial/institutional
boilers using SCR and low-NOX burners (LNB); and catalytic
cracking units, process heaters, and coke ovens using LNB and flue gas
recirculation. However, while emissions reduction potential from these
source groups is uncertain, the timeframe for these control
technologies would be subject to similar considerations and limitations
discussed in the following paragraphs.
    Among the control technologies that were evaluated in the Final
Non-EGU TSD, the EPA identified six categories of common control
technologies available for different non-EGU emissions source
categories. Id. at 19. For four of the technology categories (SNCR,
SCR, LNB, and mid-kiln firing), the EPA preliminarily estimated that
such controls for non-EGUs could be installed in approximately 1 year
or less in some unit-specific cases. Installation time estimates
presented in the Final Non-EGU TSD begin with control technology bid
evaluation (bids from vendors) and end with the startup of the control
technology.\79\ See Final Non-EGU TSD at 20. For the other two
technology categories (biosolid injection technology (BSI) and OXY-
firing), as well as one emissions source category (RICE), the EPA had
no installation time estimates or uncertain installation time
estimates. For example, the EPA found that the use of BSI is not
widespread, and therefore the EPA does not have reliable information
regarding the time required to install the technology on cement kilns.
The installation timing for OXY-firing is similarly uncertain because
the control technology is installed only at the time of a furnace
rebuild, and such rebuilds occur at infrequent intervals of a decade or
more.
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    \79\ In this document, we present different installation time
estimates for SCRs for EGUs and non-EGUs. These installation times
are not inconsistent because: (i) The EGU time estimate of 39 months
mentioned above is based on multi-boiler installation and factors in
a pre-vendor bid engineering study consideration; and (ii) the non-
EGU SCR installation time estimates are based on single-unit
installation and do not factor in pre-vendor bid evaluation.
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    For those categories for which preliminary estimates were
available, as noted in the Final Non-EGU TSD, the single-unit
installation time estimates provided do not account for additional
important considerations in assessing the full amount of time needed
for installation of NOX control measures at non-EGUs; those
considerations include time, labor, and materials needed for
programmatic adoption of measures and time required for installing
controls on multiple sources in a few to several non-EGU sectors across
the region.
    The preliminary estimates of installation time shown in the Final
Non-EGU TSD are for installation at a single source and do not account
for the time required for installing controls to achieve sector-wide
compliance. When considering installation of control measures on
sources regionally and across non-EGU sectors, the time for full
sector-wide compliance is uncertain, but it is likely longer than the
installation times shown for control measures as mentioned above for
individual sources in the Final Non-EGU TSD. As discussed earlier with
respect to EGUs, regional, sector-wide compliance could be slowed down
by limited vendor capacity, limited available skilled labor for
manufacturers such as boilermakers (who produce steel fabrications,
including those for pollution control equipment), availability of raw
materials and equipment (e.g., cranes) for control technology
construction, and bottlenecks in delivery and installation of control
technologies. Some of the difficulties with control technology
installation as part of regional, sector-wide compliance at non-EGUs,
such as availability of skilled labor and materials, could also have an
impact on monitor installation at such sources.

EPA currently has insufficient information on vendor capacity and
limited experience with suppliers of control technologies and major
engineering firms, which results in uncertainty in the installation
time estimates for non-EGU sectors. In summary, there is significant
uncertainty regarding the implementation timeframes for various
NOX control technologies for non-EGUs. While the EPA has
developed preliminary estimates for some potential control
technologies, these estimates do not account for additional
considerations such as the impacts of sector- and region-wide
compliance. For purposes of this analysis, the EPA believes that it is
reasonable to assume that it is likely that an expeditious timeframe
for installing sector- or region-wide controls on non-EGU sources may
collectively require four years or more.
3. Focusing on 2023 for Analysis
    As discussed in section III.B, the EPA weighed several factors to
identify an appropriate future analytic year for evaluating interstate
transport obligations for the 2008 ozone NAAQS. First, the EPA
identified the relevant attainment dates to guide the EPA's
consideration as 2021 and 2027, respectively the Serious and Severe
area attainment dates for the 2008 ozone NAAQS.
    Second, the EPA identified and analyzed the feasibility and timing
needed for installing additional NOX emissions controls. As
discussed in section III.B.2, the EPA believes it is appropriate to
assume that planning for, installing, and commencing operation of new