[Federal Register Volume 86, Number 111 (Friday, June 11, 2021)]
[Proposed Rules]
[Pages 31218-31225]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-12164]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R04-OAR-2020-0221; FRL-10024-71-Region 4]


Air Plan Approval; TN; Knoxville Area Limited Maintenance Plan 
for the 1997 8-Hour Ozone NAAQS

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve a state implementation plan (SIP) revision submitted by the 
State of Tennessee, through the Tennessee Department of Environment and 
Conservation (TDEC), Air Pollution Control Division, via a letter dated 
January 23, 2020. The SIP revision includes the 1997 8-hour ozone 
national ambient air quality standards (NAAQS) Limited Maintenance Plan 
(LMP) for the Knoxville, Tennessee Area (hereinafter referred to as the 
``Knoxville Area'' or ``Area''). The Knoxville Area, as defined in this 
proposed action, is comprised of Jefferson, Loudon, and Sevier Counties 
in their entireties, the portion of Cocke County that falls within the 
boundary of the Great Smoky Mountains National Park, and a portion of 
Anderson County that excludes the area surrounding TVA Bull Run Fossil 
Plant. EPA is proposing to approve the Knoxville Area LMP because it 
provides for the maintenance of the 1997 8-hour ozone NAAQS within the 
Knoxville Area through the end of the second 10-year portion of the 
maintenance period. The effect of this action would be to make certain 
commitments related to

[[Page 31219]]

maintenance of the 1997 8-hour ozone NAAQS in the Knoxville Area 
federally enforceable as part of the Tennessee SIP.

DATES: Written comments must be received at the address below on or 
before July 12, 2021.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R04-
OAR-2020-0221 at http://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from Regulations.gov. 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. 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.

FOR FURTHER INFORMATION CONTACT: Sarah LaRocca, Air Regulatory 
Management Section, Air Planning and Implementation Branch, Air and 
Radiation Division, U.S. Environmental Protection Agency, Region 4, 61 
Forsyth Street SW, Atlanta, Georgia 30303-8960. The telephone number is 
(404) 562-8994. Ms. LaRocca can also be reached via electronic mail at 
[email protected].

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Summary of EPA's Proposed Action
II. Background
III. Tennessee's SIP Submittal
IV. EPA's Evaluation of Tennessee's SIP Submittal
    A. Attainment Emissions Inventory
    B. Maintenance Demonstration
    C. Monitoring Network and Verification of Continued Attainment
    D. Contingency Plan
    E. Conclusion
V. Transportation Conformity and General Conformity
VI. Proposed Action
VII. Statutory and Executive Order Reviews

I. Summary of EPA's Proposed Action

    In accordance with the Clean Air Act (CAA or Act), EPA is proposing 
to approve the Knoxville Area LMP for the 1997 8-hour ozone NAAQS, 
adopted by TDEC on January 8, 2020, and submitted by TDEC as a revision 
to the Tennessee SIP on January 23, 2020. In 2004, the Tennessee 
counties of Anderson, Blount, Knox, Jefferson, Loudon, and Sevier in 
their entireties, and a portion of Cocke County were designated as 
nonattainment for the 1997 8-hour ozone NAAQS (hereinafter referred to 
as the ``Knoxville 1997 NAAQS Area''.\1\ Subsequently, in 2011, after a 
clean data determination \2\ and EPA's approval of a maintenance plan, 
the Knoxville 1997 NAAQS Area was redesignated to attainment for the 
1997 8-hour ozone NAAQS.
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    \1\ The ``Knoxville Area'' is a subset of the ``Knoxville 1997 
NAAQS Area'', which is further defined later in this action.
    \2\ See 75 FR 62470 (October 12, 2010).
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    The Knoxville Area LMP, submitted by TDEC on January 23, 2020, is 
designed to maintain the 1997 8-hour ozone NAAQS within the Knoxville 
Area through the end of the second 10-year portion of the maintenance 
period beyond redesignation. EPA is proposing to approve the plan 
because it meets all applicable requirements under CAA sections 110 and 
175A.
    As a general matter, the Knoxville Area LMP relies on the same 
control measures and contingency provisions to maintain the 1997 8-hour 
ozone NAAQS during the second 10-year portion of the maintenance period 
as the maintenance plan submitted by TDEC for the first 10-year period.

II. Background

    Ground-level ozone is formed when oxides of nitrogen 
(NOX) and volatile organic compounds (VOC) react in the 
presence of sunlight. These two pollutants, referred to as ozone 
precursors, are emitted by many types of pollution sources, including 
on- and off-road motor vehicles and engines, power plants and 
industrial facilities, and smaller area sources such as lawn and garden 
equipment and paints. Scientific evidence indicates that adverse public 
health effects occur following exposure to ozone, particularly in 
children and in adults with lung disease. Breathing air containing 
ozone can reduce lung function and inflame airways, which can increase 
respiratory symptoms and aggravate asthma and other lung diseases.
    Ozone exposure also has been associated with increased 
susceptibility to respiratory infections, medication use, doctor 
visits, and emergency department visits and hospital admissions for 
individuals with lung disease. Children are at increased risk from 
exposure to ozone because their lungs are still developing and they are 
more likely to be active outdoors, which increases their exposure.\3\
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    \3\ See ``Fact Sheet, Proposal to Revise the National Ambient 
Air Quality Standards for Ozone,'' January 6, 2010, and 75 FR 2938 
(January 19, 2010).
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    In 1979, under section 109 of the CAA, EPA established primary and 
secondary NAAQS for ozone at 0.12 parts per million (ppm), averaged 
over a 1-hour period. See 44 FR 8202 (February 8, 1979). On July 18, 
1997, EPA revised the primary and secondary NAAQS for ozone to set the 
acceptable level of ozone in the ambient air at 0.08 ppm, averaged over 
an 8-hour period. See 62 FR 38856 (July 18, 1997).\4\ EPA set the 8-
hour ozone NAAQS based on scientific evidence demonstrating that ozone 
causes adverse health effects at lower concentrations and over longer 
periods of time than was understood when the pre-existing 1-hour ozone 
NAAQS was set. EPA determined that the 8-hour ozone NAAQS would be more 
protective of human health, especially children and adults who are 
active outdoors, and individuals with a pre-existing respiratory 
disease, such as asthma.
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    \4\ In March 2008, EPA completed another review of the primary 
and secondary ozone NAAQS and tightened them further by lowering the 
level for both to 0.075 ppm. See 73 FR 16436 (March 27, 2008). 
Additionally, in October 2015, EPA completed a review of the primary 
and secondary ozone NAAQS and tightened them by lowering the level 
for both to 0.070 ppm. See 80 FR 65292 (October 26, 2015).
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    Following promulgation of a new or revised NAAQS, EPA is required 
by the CAA to designate areas throughout the nation as attaining or not 
attaining the NAAQS. On April 15, 2004, EPA designated the Knoxville 
1997 NAAQS Area, which is comprised of Anderson, Blount, Knox, 
Jefferson, Loudon, and Sevier Counties in their entireties, and the 
portion of Cocke County that falls within the boundary of the Great 
Smoky Mountains National Park, as nonattainment for the 1997 8-hour 
ozone NAAQS, and the designation became effective on June 15, 2004. See 
69 FR 23858 (April 30, 2004). Similarly, on May 21, 2012, EPA 
designated areas as unclassifiable/attainment or nonattainment for the 
2008 8-hour ozone NAAQS. EPA designated Blount and Knox Counties and 
the portion of Anderson County surrounding the TVA Bull Run Fossil 
Plantas nonattainment for the 2008 8-hour ozone NAAQS and classified as 
a marginal nonattainment area (hereinafter referred to as the 
``Knoxville 2008 NAAQS Area''). This designation became effective on 
July 20,

[[Page 31220]]

2012.\5\ In addition, on November 16, 2017, areas were designated for 
the 2015 8-hour ozone NAAQS. The Knoxville 1997 NAAQS Area \6\ was 
designated attainment/unclassifiable for the 2015 8-hour ozone NAAQS, 
with an effective date on January 16, 2018.\7\
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    \5\ See 77 FR 30088.
    \6\ The ``Knoxville 1997 NAAQS Area'' encompasses both the 
``Knoxville Area'' and the ``Knoxville 2008 NAAQS Area''.
    \7\ See 82 FR 54232 (Nov. 16, 2017).
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    A state may submit a request to redesignate a nonattainment area 
that is attaining a NAAQS to attainment, and, if the area has met other 
required criteria described in section 107(d)(3)(E) of the CAA, EPA may 
approve the redesignation request.\8\ One of the criteria for 
redesignation is to have an approved maintenance plan under CAA section 
175A. The maintenance plan must demonstrate that the area will continue 
to maintain the NAAQS for the period extending ten years after 
redesignation, and it must contain such additional measures as 
necessary to ensure maintenance and such contingency provisions as 
necessary to assure that violations of the NAAQS will be promptly 
corrected. Eight years after the effective date of redesignation, the 
state must also submit a second maintenance plan to ensure ongoing 
maintenance of the NAAQS for an additional ten years pursuant to CAA 
section 175A(b) (i.e., ensuring maintenance for 20 years after 
redesignation).
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    \8\ Section 107(d)(3)(E) of the CAA sets out the requirements 
for redesignating a nonattainment area to attainment. They include 
attainment of the NAAQS, full approval of the applicable SIP 
pursuant to CAA section 110(k), determination that improvement in 
air quality is a result of permanent and enforceable reductions in 
emissions, demonstration that the state has met all applicable 
section 110 and part D requirements, and a fully approved 
maintenance plan under CAA section 175A.
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    EPA has published long-standing guidance for states on developing 
maintenance plans.\9\ The Calcagni memo provides that states may 
generally demonstrate maintenance by either performing air quality 
modeling to show that the future mix of sources and emission rates will 
not cause a violation of the NAAQS or by showing that projected future 
emissions of a pollutant and its precursors will not exceed the level 
of emissions during a year when the area was attaining the NAAQS (i.e., 
attainment year inventory). See Calcagni memo at page 9. EPA clarified 
in three subsequent guidance memos that certain areas could meet the 
CAA section 175A requirement to provide for maintenance by showing that 
the area was unlikely to violate the NAAQS in the future, using 
information such as the area's design value \10\ being significantly 
below the standard and the area having a historically stable design 
value.\11\ EPA refers to a maintenance plan containing this streamlined 
demonstration as an LMP.
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    \9\ John Calcagni, Director, Air Quality Management Division, 
EPA Office of Air Quality Planning and Standards (OAQPS), 
``Procedures for Processing Requests to Redesignate Areas to 
Attainment,'' September 4, 1992 (Calcagni memo).
    \10\ The ozone design value for a monitoring site is the 3-year 
average of the annual fourth-highest daily maximum 8-hour average 
ozone concentrations. The design value for an ozone area is the 
highest design value of any monitoring site in the area.
    \11\ See ``Limited Maintenance Plan Option for Nonclassifiable 
Ozone Nonattainment Areas'' from Sally L. Shaver, OAQPS, dated 
November 16, 1994; ``Limited Maintenance Plan Option for 
Nonclassifiable CO Nonattainment Areas'' from Joseph Paisie, OAQPS, 
dated October 6, 1995; and ``Limited Maintenance Plan Option for 
Moderate PM10 Nonattainment Areas'' from Lydia Wegman, 
OAQPS, dated August 9, 2001. Copies of these guidance memoranda can 
be found in the docket for this proposed rulemaking.
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    EPA has interpreted CAA section 175A as permitting the LMP option 
because section 175A of the Act does not define how areas may 
demonstrate maintenance, and in EPA's experience implementing the 
various NAAQS, areas that qualify for an LMP and have approved LMPs 
have rarely, if ever, experienced subsequent violations of the NAAQS. 
As noted in the LMP guidance memoranda, states seeking an LMP must 
still submit the other maintenance plan elements outlined in the 
Calcagni memo, including: An attainment emissions inventory, provisions 
for the continued operation of the ambient air quality monitoring 
network, verification of continued attainment, and a contingency plan 
in the event of a future violation of the NAAQS. Moreover, a state 
seeking an LMP must still submit its section 175A maintenance plan as a 
revision to its SIP, with all attendant notice and comment procedures. 
While the LMP guidance memoranda were originally written with respect 
to certain NAAQS,\12\ EPA has extended the LMP interpretation of 
section 175A to other NAAQS and pollutants not specifically covered by 
the previous guidance memos.\13\
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    \12\ The prior memos addressed: Unclassifiable areas under the 
1-hour ozone NAAQS, nonattainment areas for the PM10 
(particulate matter with an aerodynamic diameter less than 10 
microns) NAAQS, and nonattainment for the carbon monoxide (CO) 
NAAQS.
    \13\ See, e.g., 79 FR 41900 (July 18, 2014) (Approval of the 
second ten-year LMP for the Grant County 1971 SO2 
maintenance area).
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    In this case, EPA is proposing to approve Tennessee's LMP because 
the State has made a showing, consistent with EPA's prior LMP guidance, 
that the Area's ozone concentrations are well below the 1997 8-hour 
ozone NAAQS and have been historically stable and that it has met the 
other maintenance plan requirements. TDEC submitted this LMP for the 
Knoxville Area to fulfill the second maintenance plan requirement in 
the Act. EPA's evaluation of the Knoxville Area's LMP is presented 
below.
    In July of 2010, TDEC submitted to EPA a request to redesignate the 
Knoxville 1997 NAAQS Area to attainment for the 1997 8-hour ozone 
NAAQS. This submittal included a plan to provide for maintenance of the 
1997 8-hour ozone NAAQS in the Knoxville 1997 NAAQS Area through 2024 
as a revision to the Tennessee SIP. EPA approved the Knoxville 1997 
NAAQS Area's Maintenance Plan and the State's request to redesignate 
the Knoxville 1997 NAAQS Area to attainment for the 1997 8-hour ozone 
NAAQS effective March 8, 2011.\14\
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    \14\ See 76 FR 12587 (March 8, 2011).
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    Under CAA section 175A(b), states must submit a revision to the 
first maintenance plan eight years after redesignation to provide for 
maintenance of the NAAQS for ten additional years following the end of 
the first 10-year period. EPA's final implementation rule for the 2008 
8-hour ozone NAAQS revoked the 1997 8-hour ozone NAAQS and stated that 
one consequence of revocation was that areas that had been redesignated 
to attainment (i.e., maintenance areas) for the 1997 NAAQS no longer 
needed to submit second 10-year maintenance plans under CAA section 
175A(b).\15\ On July 13, 2015, EPA redesignated the Knoxville 2008 
NAAQS Area as attainment for the 2008 8-hour ozone NAAQS, and the 
designation became effective on August 12, 2015. See 80 FR 39970 (July 
13, 2015).
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    \15\ See 80 FR 12315 (March 6, 2015).
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    In South Coast Air Quality Management District v. EPA, the United 
States Court of Appeals for the District of Columbia Circuit (D.C. 
Circuit) vacated EPA's interpretation that, because of the revocation 
of the 1997 8-hour ozone NAAQS, second maintenance plans were not 
required for ``orphan maintenance areas,'' i.e., areas that had been 
redesignated to attainment for the 1997 8-hour ozone NAAQS maintenance 
areas and were designated attainment for the 2008 ozone NAAQS. South 
Coast, 882 F.3d 1138 (D.C. Cir. 2018). Thus, states with these ``orphan 
maintenance areas'' under the 1997 8-hour ozone NAAQS must submit 
maintenance plans for the

[[Page 31221]]

second maintenance period. Accordingly, on January 23, 2020, Tennessee 
submitted a second maintenance plan for the Knoxville Area that shows 
that the Area is expected to remain in attainment of the 1997 8-hour 
ozone NAAQS through 2031.
    In recognition of the continuing record of air quality monitoring 
data showing ambient 8-hour ozone concentrations in the Knoxville Area 
well below the 1997 8-hour ozone NAAQS, TDEC chose the LMP option for 
the development of its second 1997 8-hour ozone NAAQS maintenance plan. 
On January 8, 2020, TDEC adopted the second 10-year 1997 8-hour ozone 
maintenance plan, and on January 23, 2020, TDEC submitted the Knoxville 
Area LMP to EPA as a revision to the Tennessee SIP.

III. Tennessee's SIP Submittal

    As mentioned above, on January 23, 2020, TDEC submitted the 
Knoxville Area 1997 8-Hour Ozone NAAQS LMP to EPA as a revision to the 
Tennessee SIP. The submittal includes the LMP, air quality data, 
emissions inventory information, and appendices as well as 
certification of adoption of the plan by TDEC. Appendices to the plan 
include comments and responses between EPA and TDEC; documentation of 
notice, hearing, and public participation prior to adoption of the plan 
by TDEC on January 8, 2020; interagency consultation; and Air Pollution 
Control Board order, which notes that Tennessee's LMP submittal for the 
remainder of the 20-year maintenance period for the Knoxville Area is 
in response to the D.C. Circuit's decision overturning aspects of EPA's 
Implementation Plan rule. The Knoxville Area LMP does not include any 
additional emissions reduction measures but relies on the same 
emissions reduction strategy as its first 10-year Maintenance Plan that 
provides for the maintenance of the 1997 8-hour ozone NAAQS through 
2024. Specifically, the measures upon which the second 10-year LMP for 
the Knoxville Area relies include the continuation of the stage 1 
gasoline vapor recovery rule and a statewide Motor Vehicle Tampering 
rule in Chapter 1200-03-36. It also relies on continued implementation 
of federal measures (e.g., interstate transport rules such as Cross 
State Air Pollution Rule (CSAPR) \16\ and CSAPR Update \17\).
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    \16\ See 76 FR 48208 (August 8, 2011).
    \17\ See 81 FR 74504 (October 26, 2016).
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IV. EPA's Evaluation of Tennessee's SIP Submittal

    EPA has reviewed the Knoxville Area's LMP which is designed to 
maintain the 1997 8-hour ozone NAAQS within the Knoxville Area through 
the end of the 20-year period beyond redesignation, as required under 
CAA section 175A(b). The following is a summary of EPA's interpretation 
of the section 175A requirements \18\ and EPA's evaluation of how each 
requirement is met.
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    \18\ See Calcagni memo.
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A. Attainment Emissions Inventory

    For maintenance plans, a state should develop a comprehensive, 
accurate inventory of actual emissions for an attainment year to 
identify the level of emissions which is sufficient to maintain the 
NAAQS. A state should develop this inventory consistent with EPA's most 
recent guidance on emissions inventory development. For ozone, the 
inventory should be based on typical summer day emissions of VOC and 
NOX, as these pollutants are precursors to ozone formation. 
The Knoxville Area's LMP includes an ozone attainment inventory for the 
Knoxville Area that reflects typical summer day emissions in 2014. 
Table 1 and Table 2 present a summary of the inventory for 2014 
contained in the LMP.
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    \19\ See email from James Johnston, TDEC, to Lynorae Benjamin, 
EPA Region 4 (December 15, 2020), available in the docket for this 
proposed rulemaking.
    \20\ See email from James Johnston, TDEC, to Lynorae Benjamin, 
EPA Region 4 (December 15, 2020), available in the docket for this 
proposed rulemaking.

                                      Table 1--2014 Typical Summer Day 8-Hour NOX Emissions for the Knoxville Area
                                                                    [Tons/summer day]
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                         County                                Fire          Nonpoint         Nonroad         Onroad           Point           Total
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Anderson................................................          * 0.00            1.70            0.81            5.35            4.93           12.79
Cocke...................................................         ** 0.00            0.39            0.41            3.34            0.09          * 4.23
Jefferson...............................................          * 0.00            0.56            1.05            7.97            0.00            9.58
Loudon..................................................          * 0.00            0.64            0.77            5.45            2.31            9.17
Sevier..................................................            0.09            0.23            0.90            6.05            0.16          * 7.43
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................            0.09            3.52            3.94         * 28.16            7.49         * 43.20
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* These total emissions values for both NOX and VOC, respectively, differ from Tennessee's submittal and have been re-calculated to accurately reflect
  the total for each sector and county.\19\
** The values, while greater than zero, do not meet the two significant figure rounding convention.


                  Table 2--2014 Typical Summer Day 8-Hour VOC Emissions for the Knoxville Area
                                                [Tons/summer day]
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              County                    Fire       Nonpoint     Nonroad       Onroad       Point        Total
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Anderson..........................       * 0.00         6.79         1.85         3.14         0.64        12.42
Cocke.............................      ** 0.00         1.67         2.44         1.47         0.31       * 5.89
Jefferson.........................       * 0.00         2.80         2.90         2.57         0.26         8.53
Loudon............................       * 0.00         2.03         1.93         2.08         4.55      * 10.59
Sevier............................         1.43         2.76         6.72         3.31         0.03      * 14.25
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    Total.........................         1.43        16.05      * 15.84      * 12.57         5.79      * 51.68
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* These total emissions values for both NOX and VOC, respectively, differ from Tennessee's submittal and have
  been re-calculated to accurately reflect the total for each sector and county.\20\

[[Page 31222]]

 
** The values, while greater than zero, do not meet the two significant figure rounding convention.

    The Emissions Inventory section of the Knoxville Area's LMP 
describes the methods, models, and assumptions used to develop the 
attainment inventory. As described in the Emissions Inventory section 
of the LMP, TDEC generally relied upon emissions inventory information 
from the EPA 2014 version 7.0 air quality modeling platform (2014v7.0 
platform), which is based on the 2014 NEI. The emissions data in the 
2014v7.0 platform are primarily based on the 2014NEIv1 for point 
sources, nonpoint sources, commercial marine vessels (CMV), onroad and 
nonroad mobile sources, and fires. This 2014 modeling platform includes 
all criteria air pollutants (CAPs) and precursors and two groups of 
hazardous air pollutants (HAPs).
    Nonroad mobile source emissions in the 2014NEIv1, in part, were 
estimated using the latest available version of EPA's motor vehicle 
emissions model, MOVES 2014a (which includes estimates of nonroad 
emissions like agriculture, commercial and mining, industrial and 
recreational equipment, and commercial and residential lawn and garden 
equipment). Locomotives, aircraft, and marine nonroad sources are not 
included in MOVES, and TDEC relied on EPA-generated emissions for these 
sectors.\21\ Onroad mobile sources in the 2014NEIv1, were estimated 
using MOVES2014a and the latest planning assumptions regarding vehicle 
type, activity, and vehicle speeds to estimate vehicular emissions for 
2014. MOVES2014a was used with inputs, where provided, by state and 
local agencies, in combination with EPA-generated default data. In its 
entirety, the 2014v7.0 platform estimates for vehicles reflect 
emissions inventories and ancillary data files used for emissions 
modeling, as well as the meteorological, initial condition, and 
boundary condition files need to run the air quality model.
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    \21\ EPA developed emissions for these sectors based on AP-42 
emissions factors, and information supplied by the Eastern Regional 
Technical Advisory Committee for locomotives and Federal Aviation 
Administration's Emissions and Dispersion Modeling System (since 
replaced by the Aviation Environmental Design Tool).
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B. Maintenance Demonstration

    The maintenance demonstration requirement is considered to be 
satisfied in a LMP if the state can provide sufficient weight of 
evidence indicating that air quality in the area is well below the 
level of the NAAQS, that past air quality trends have been shown to be 
stable, and that the probability of the area experiencing a violation 
over the second 10-year maintenance period is low.\22\ These criteria 
are evaluated below with regard to the Knoxville Area.
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    \22\ See footnote 9.
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1. Evaluation of Ozone Air Quality Levels
    To attain the 1997 8-hour ozone NAAQS, the three-year average of 
the fourth-highest daily maximum 8-hour average ozone concentrations 
(design value) at each monitor within an area must not exceed 0.08 ppm. 
Based on the rounding convention described in 40 CFR part 50, Appendix 
I, the NAAQS is attained if the design value is 0.084 ppm or below. At 
the time of submission, EPA evaluated quality assured and certified 
2016-2018 monitoring data and determined that the design value for the 
Knoxville Area was 0.067 ppm, or 80 percent of the level of the 1997 8-
hour ozone NAAQS. Based on quality assured and certified monitoring 
data for 2018-2020, the current design value for the Knoxville Area is 
0.063 ppm, or 75 percent of the level of the 1997 8-hour ozone NAAQS. 
Consistent with prior guidance, EPA believes that if the most recent 
air quality design value for the area is at a level that is well below 
the NAAQS (e.g., below 85 percent of the NAAQS, or in this case below 
0.071 ppm), then EPA considers the state to have met the section 175A 
requirement for a demonstration that the area will maintain the NAAQS 
for the requisite period. Such a demonstration assumes continued 
applicability of prevention of significant deterioration requirements 
and any control measures already in the SIP and that Federal measures 
will remain in place through the end of the second 10-year maintenance 
period, absent a showing consistent with section 110(l) that such 
measures are not necessary to assure maintenance.
    Table 3 presents the design values for each monitor in the 
Knoxville Area over the 2008-2020 period. As shown in Table 3, all 
sites have been below the level of the 1997 8-hour ozone NAAQS since 
the area was redesignated to attainment, and the most current design 
value is below the level of 85 percent of the NAAQS, consistent with 
prior LMP guidance.
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    \23\ In the 2017 Annual Network Plan approval letter, EPA 
approved a combined design value for ozone monitors 47-105-0108 and 
47-105-0109 in Loudon County due to relocation of monitor. EPA's 
approval letter of the 2017 Annual Network Plan can be found in the 
docket for this action.

                             Table 3--1997 8-Hour Ozone NAAQS Design Values (ppm) at Monitoring Sites in the Knoxville 1997 NAAQS Area for the 2008-2020 Time Period
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                                                                                                2008-    2009-    2010-    2011-    2012-    2013-    2014-    2015-    2016-    2017-    2018-
                  Location                                 County               AQS  site ID     2010     2011     2012     2013     2014     2015     2016     2017     2018     2019     2020
                                                                                                  DV       DV       DV       DV       DV       DV       DV       DV       DV       DV       DV
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Freels Bend.................................  Anderson.......................     47-001-0101     0.07     0.07    0.073    0.069      (*)    0.061    0.063    0.064    0.064    0.064    0.061
Look Rock...................................  Blount.........................     47-009-0101    0.077    0.077    0.079    0.074    0.067    0.065    0.067    0.067    0.067    0.065    0.063
Cades Cove..................................  Blount.........................     47-009-0102    0.069    0.068    0.068    0.063    0.060    0.059    0.060    0.061    0.062    0.060    0.058
New Market..................................  Jefferson......................     47-089-0002    0.074    0.073    0.078    0.073    0.071    0.067    0.068    0.067    0.066    0.065    0.063
East Knox...................................  Knox...........................     47-093-0021    0.071    0.069    0.071    0.067    0.063    0.061    0.064    0.064    0.065    0.063    0.061
Spring Hill.................................  Knox...........................     47-093-1020    0.076    0.071    0.074    0.070    0.067    0.063    0.066    0.067    0.067    0.063    0.058
Loudon \+\..................................  Loudon.........................     47-105-0109    0.073    0.072    0.075    0.070    0.068    0.066    0.069    0.068    0.067    0.063    0.062
Cove Mountain...............................  Sevier.........................     47-155-0101    0.076    0.075    0.076    0.072    0.068    0.067    0.067    0.066    0.066    0.065    0.063
Clingman's Dome [supcaret]..................  Sevier.........................     47-155-0102  [supcar  [supcar  [supcar  [supcar  [supcar  [supcar  [supcar  [supcar  [supcar  [supcar    0.063
                                                                                                   et]      et]      et]      et]      et]      et]      et]      et]      et]      et]
                                                                                                 0.076    0.075    0.075    0.071    0.067    0.065    0.066    0.065    0.065    0.063
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* Incomplete design value due to annual values not meeting completeness criteria.
\+\ On March 16, 2016, the EPA approved the relocation of the Loudon Pope monitoring site (AQS ID 47-105-0108) to the Loudon Elementary School monitoring site (AQS ID 47-105-0109). The ozone
  monitor was relocated to the Loudon Elementary School site on March 3, 2017. The EPA approved the calculation of a combined DV for the Loudon Pope site and the Loudon Elementary School site.
  Design values prior to 2017 are calculated using data from the Loudon Pope monitoring site.\23\
[supcaret] The Clingman's Dome site has limited accessibility and difficulty in using the site's solar power system during the winter months. Due to the limited access in the first two months
  of the ozone season, annual design values did not meet data completeness. A waiver for a delayed ozone season starting no later than May 1 for the Clingman's Dome monitor was submitted by
  the National Park Service on April 28, 2016, and approved by EPA on May 3, 2016.


[[Page 31223]]

    Therefore, the Knoxville Area is eligible for the LMP option, and 
EPA proposes to find that the long record of monitored ozone 
concentrations that attain the NAAQS, together with the continuation of 
existing VOC and NOX emissions control programs, adequately 
provide for the maintenance of the 1997 8-hour ozone NAAQS in the 
Knoxville Area through the second 10-year maintenance period and 
beyond.
    Additional supporting information that the Area is expected to 
continue to maintain the NAAQS can be found in projections of future 
year design values that EPA recently completed to assist states with 
development of interstate transport SIPs for the 2015 ozone NAAQS.\24\ 
Those projections, made for the year 2023, show that the highest design 
value of any monitor in the Knoxville Area is expected to be 0.058 ppm.
---------------------------------------------------------------------------

    \24\ See the spreadsheet titled ``Ozone Monitoring Site Design 
Values for 2008 through 2017 and for 2023'' at https://www.epa.gov/airmarkets/memo-and-supplemental-information-regarding-interstate-transport-sips-2015-ozone-naaqs.
---------------------------------------------------------------------------

2. Stability of Ozone Levels
    As discussed above, the Knoxville Area has maintained air quality 
well below the 1997 8-hour ozone NAAQS over the past eleven years. 
Additionally, the design value data shown within Table 3 illustrates 
that ozone levels have been relatively stable over this timeframe, with 
a modest downward trend. For example, the data within Table 3 indicates 
that the largest, year over year change in design value at any one 
monitor during these eleven years was five parts per billion which 
occurred between the 2009-2011 design value and the 2010-2012 design 
value as an increase, representing only a seven percent change, and 
between the 2017-2019 design value and the 2018-2020 design value as a 
decrease, representing an eight percent change. Furthermore, the 
overall trend in design values for the Knoxville 1997 NAAQS Area 
between 2008-2020 shows a decrease of 17 to 18 percent at the three 
highest monitors, Cove Mountain monitor 47-155-0101, Clingman's Dome 
monitor 47-155-0102, and Blount County monitor 47-009-0101 
respectively. This downward trend in ozone levels, coupled with the 
relatively small, year-over-year variation in ozone design values, 
makes it reasonable to conclude that the Knoxville Area will not exceed 
the 1997 8-hour ozone NAAQS during the second 10-year maintenance 
period.
3. Projected Emissions
    Although under the LMP option there is no requirement to project 
emissions over the maintenance period, TDEC included an analysis of 
ozone precursor emissions trends expected over the course of the second 
maintenance plan. TDEC provided a VOC and NOX emissions 
trends analysis from 2014 to 2028. Tennessee selected 2014 as a 
baseline for the projection because that was the most recent year for 
which a complete set of data was available from the EPA's National 
Emissions Inventory (NEI) database at the time that the State developed 
its second maintenance plan for the Area.\25\ Projected emissions data 
for the year 2028 were obtained from EPA,\26\ and these data represent 
EPA emissions projections that are available for a date furthest out 
into the future.\27\ The emissions projection trends show that between 
2014 and 2028, VOC emissions are estimated to fall by 40 percent, and 
NOX emissions are estimated to fall by 38 percent within the 
Knoxville Area. These projected declining emissions trends further 
support the conclusion that it is unlikely that the Knoxville Area 
would violate the 1997 8-hour ozone NAAQS in the future. Table 4 and 
Table 5 present a summary of projected emissions for 2028 contained in 
the maintenance plan.
---------------------------------------------------------------------------

    \25\ The 2017 NEI is the most recent NEI, but it was unavailable 
to Tennessee when the State developed its SIP revision.
    \26\ https://www.epa.gov/air-emissions-modeling/2014-2016-version-7-air-emissions-modeling-platforms.
    \27\ EPA's emissions projections to 2028 were made from the 2011 
NEI, as that iteration of the NEI was the most recently available 
version when the projection work was performed. Although this 
projection does not correspond exactly with the end of the second 
ten-year maintenance period, it provides additional support for 
EPA's proposed finding that the Area will maintain the NAAQS due to 
its low and historically stable design values. See the Emissions 
Inventory section of the LMP for additional information regarding 
the 2028 projections.

                  Table 4--2028 Typical Summer Day 8-Hour NOX Emissions for the Knoxville Area
                                                [Tons/summer day]
----------------------------------------------------------------------------------------------------------------
              County                    Fire       Nonpoint     Nonroad       Onroad       Point        Total
----------------------------------------------------------------------------------------------------------------
Anderson..........................      ** 0.00         4.39         0.47         1.29         6.69        12.84
Cocke.............................         0.02         0.37         0.28         1.21         0.04       * 1.92
Jefferson.........................       * 0.00         0.62         0.74         3.04         0.08       * 4.48
Loudon............................       * 0.00         0.84         0.49         2.26         1.60       * 5.19
Sevier............................         0.04         0.31         0.57         1.27         0.12       * 2.31
                                   -----------------------------------------------------------------------------
Total.............................       * 0.06         6.53         2.55         9.07         8.53      * 26.74
----------------------------------------------------------------------------------------------------------------
* These total emissions values for both NOX and VOC, respectively, differ from Tennessee's submittal and have
  been re-calculated to accurately reflect the total for each sector and county.\19\
** The values, while greater than zero, do not meet the two significant figure rounding convention.


                  Table 5--2028 Typical Summer Day 8-Hour VOC Emissions for the Knoxville Area
                                                [Tons/summer day]
----------------------------------------------------------------------------------------------------------------
              County                    Fire       Nonpoint     Nonroad       Onroad       Point        Total
----------------------------------------------------------------------------------------------------------------
Anderson..........................      ** 0.00         5.75         1.19         0.70         0.95       * 8.59
Cocke.............................         0.22         1.33         1.45         0.41         0.35       * 3.76
Jefferson.........................       * 0.00         2.23         1.37         0.76         0.16         4.52
Loudon............................       * 0.00         1.96         1.09         0.71         1.61         5.37
Sevier............................         0.45         3.11         4.25         0.89         0.02         8.72
                                   -----------------------------------------------------------------------------

[[Page 31224]]

 
Total.............................         0.67        14.38       * 9.35       * 3.47       * 3.09      * 30.96
----------------------------------------------------------------------------------------------------------------
* These total emissions values for both NOX and VOC, respectively, differ from Tennessee's submittal and have
  been re-calculated to accurately reflect the total for each sector and county.\19\
** The values, while greater than zero, do not meet the two significant figure rounding convention.

C. Monitoring Network and Verification of Continued Attainment

    EPA periodically reviews the ozone monitoring network that TDEC 
operates and maintains in accordance with 40 CFR part 58. This network 
plan, which is submitted annually to EPA, is consistent with the 
ambient air quality monitoring network assessment. The annual network 
plan developed by TDEC follows a public notification and review 
process. EPA has reviewed and approved the State's 2020 Ambient Air 
Monitoring Network Plan (``2020 Annual Network Plan'').\28\
---------------------------------------------------------------------------

    \28\ The letter approving the network plan is in the docket for 
this proposed rulemaking.
---------------------------------------------------------------------------

    To verify the attainment status of the Area over the maintenance 
period, the maintenance plan should contain provisions for continued 
operation of an appropriate, EPA-approved monitoring network in 
accordance with 40 CFR part 58. As noted above, TDEC's monitoring 
network in the Knoxville 1997 NAAQS Area has been approved by EPA in 
accordance with 40 CFR part 58, and the State has committed to continue 
to maintain a network in accordance with EPA requirements. EPA 
therefore proposes to find that TDEC's monitoring network is adequate 
to verify continued attainment of the 1997 8-hour ozone NAAQS in the 
Knoxville Area.

D. Contingency Plan

    Section 175A(d) of the CAA requires that a maintenance plan include 
contingency provisions. The purpose of such contingency provisions is 
to prevent future violations of the NAAQS or to promptly remedy any 
NAAQS violations that might occur during the maintenance period. These 
contingency measures are required to be implemented expeditiously once 
they are triggered by a future violation of the NAAQS or some other 
trigger. The state should identify specific triggers which will be used 
to determine when the contingency measures need to be implemented.
    The LMP states that the trigger is a Quality Assured/Quality 
Controlled (QA/QC) violating design value of the 1997 8-hour ozone 
NAAQS in the Knoxville Area.\29\ If this trigger is activated, the 
maintenance plan requires Tennessee to conduct a study to determine the 
cause of the higher ozone value, whether from an event not likely to 
recur or from an increasing trend in emissions that threatens the 
continued maintenance of the NAAQS. Tennessee will adopt and implement 
appropriate contingency measures tailored to the source of the 
violation (or increased concentrations) as expeditiously as 
practicable, but no later than 18 to 24 months after the trigger 
event.\30\
---------------------------------------------------------------------------

    \29\ If QA/QC data indicates a violating design value for the 8-
hour ozone NAAQS, then the triggering event will be the date of the 
design value violation, and not the final QA/QC date. However, if 
initial monitoring data indicates a possible design value violation 
but later QA/QC indicates that a NAAQS violation did not occur, then 
a triggering even will not have occurred, and contingency measures 
will not need to be implemented.
    \30\ See the Contingency Plan section of the LMP for further 
information regarding the contingency plan, including measures that 
Tennessee will consider for adoption if the trigger is activated.
---------------------------------------------------------------------------

    EPA proposes to find that the contingency provisions in Tennessee's 
second maintenance plan for the 1997 8-hour ozone NAAQS meet the 
requirements of the CAA section 175A(d).

E. Conclusion

    EPA proposes to find that the Knoxville Area LMP for the 1997 8-
hour ozone NAAQS includes an approvable update of the various elements 
(including attainment inventory, assurance of adequate monitoring and 
verification of continued attainment, and contingency provisions) of 
the initial EPA-approved Maintenance Plan for the 1997 8-hour ozone 
NAAQS. EPA also proposes to find that the Knoxville Area, qualifies for 
the LMP option, and adequately demonstrates maintenance of the 1997 8-
hour ozone NAAQS through the documentation of monitoring data showing 
maximum 1997 8-hour ozone levels below the NAAQS and historically 
stable design values. EPA believes the Knoxville Area's LMP, which 
retains all existing control measures in the SIP, is sufficient to 
provide for maintenance of the 1997 8-hour ozone NAAQS in the Knoxville 
Area over the second maintenance period (i.e., through 2031) and 
thereby satisfies the requirements for such a plan under CAA section 
175A(b). EPA is therefore proposing to approve Tennessee's January 23, 
2020, submission of the Knoxville Area's LMP as a revision to the 
Tennessee SIP.

V. Transportation Conformity and General Conformity

    Transportation conformity is required by section 176(c) of the CAA. 
Conformity to a SIP means that transportation activities will not 
produce new air quality violations, worsen existing violations, or 
delay timely attainment of the NAAQS. See CAA 176(c)(1)(A) and (B). 
EPA's transportation conformity rule at 40 CFR part 93 subpart A 
requires that transportation plans, programs, and projects conform to 
SIPs and establishes the criteria and procedures for determining 
whether they conform. The conformity rule generally requires a 
demonstration that emissions from the Regional Transportation Plan 
(RTP) and the Transportation Improvement Program (TIP) are consistent 
with the motor vehicles emissions budget (MVEB) contained in the 
control strategy SIP revision or maintenance plan. See 40 CFR 93.101, 
93.118, and 93.124. A MVEB is defined as ``the portion of the total 
allowable emissions defined in the submitted or approved control 
strategy implementation plan revision or maintenance plan for a certain 
date for the purpose of meeting reasonable further progress milestones 
or demonstrating attainment or maintenance of the NAAQS, for any 
criteria pollutant or its precursors, allocated to highway and transit 
vehicle use and emissions.'' See 40 CFR 93.101.
    Under the conformity rule, LMP areas may demonstrate conformity 
without a regional emissions analysis. See 40 CFR 93.109(e). On 
September 15, 2010, EPA made a finding that the MVEBs for the first 10 
years of the 1997 8-hour ozone maintenance plan for the Knoxville 1997 
NAAQS Area were adequate for transportation conformity purposes. In a 
Federal Register notice dated September 15, 2010, EPA notified the 
public of that finding. See 75 FR 55977. This adequacy determination 
became

[[Page 31225]]

effective on September 30, 2010. After approval of this LMP or an 
adequacy finding for this LMP, there is no requirement to meet the 
budget test pursuant to the transportation conformity rule for the 
maintenance area. All actions that would require a transportation 
conformity determination for the Knoxville 1997 NAAQS Area under EPA's 
transportation conformity rule provisions are considered to have 
already satisfied the regional emissions analysis and ``budget test'' 
requirements in 40 CFR 93.118 as a result of EPA's adequacy finding for 
this LMP. See 69 FR 40004 (July 1, 2004). The Knoxville 2008 NAAQS Area 
needs to continue to meet all of the applicable requirements of the 
transportation conformity regulations, including the need for a 
regional emissions analysis and comparison of the results of the 
regional emissions analysis to the applicable MVEB for the 2008 8-hour 
ozone NAAQS.
    However, because LMP areas are still maintenance areas, certain 
aspects of transportation conformity determinations still will be 
required for transportation plans, programs, and projects. 
Specifically, for such determinations, RTPs, TIPs, and transportation 
projects still will have to demonstrate that they are fiscally 
constrained (40 CFR 93.108) and meet the criteria for consultation (40 
CFR 93.105) and Transportation Control Measure implementation in the 
conformity rule provisions (40 CFR 93.113) as well as meet the hot-spot 
requirements for projects (40 CFR 93.116).\31\ Additionally, conformity 
determinations for RTPs and TIPs must be determined no less frequently 
than every four years, and conformity of plan and TIP amendments and 
transportation projects is demonstrated in accordance with the timing 
requirements specified in 40 CFR 93.104. In addition, in order for 
projects to be approved they must come from a currently conforming RTP 
and TIP. See 40 CFR 93.114 and 40 CFR 93.115. The Knoxville 2008 NAAQS 
Area must continue to meet all of the applicable requirements of the 
general conformity regulations.
---------------------------------------------------------------------------

    \31\ A conformity determination that meets other applicable 
criteria in Table 1 of paragraph (b) of this section (93.109(e)) is 
still required, including the hot-spot requirements for projects in 
CO, PM10, and fine particulate matter (PM2.5) 
areas.
---------------------------------------------------------------------------

VI. Proposed Action

    Under sections 110(k) and 175A of the CAA and for the reasons set 
forth above, EPA is proposing to approve the Knoxville Area's LMP for 
the 1997 8-hour ozone NAAQS, submitted by TDEC on January 23, 2020, as 
a revision to the Tennessee SIP. EPA is proposing to approve the 
Knoxville Area LMP because it includes an acceptable update of the 
various elements of the 1997 8-hour ozone NAAQS Maintenance Plan 
approved by EPA for the first 10-year period (including emissions 
inventory, assurance of adequate monitoring and verification of 
continued attainment, and contingency provisions), and retains the 
relevant provisions of the SIP.
    EPA also finds that the Knoxville Area qualifies for the LMP option 
and that therefore the Knoxville Area's LMP adequately demonstrates 
maintenance of the 1997 8-hour ozone NAAQS through documentation of 
monitoring data showing maximum 1997 8-hour ozone levels well below the 
NAAQS and continuation of existing control measures. EPA believes the 
Knoxville Area's 1997 8-Hour Ozone LMP to be sufficient to provide for 
maintenance of the 1997 8-hour ozone NAAQS in the Knoxville Area over 
the second 10-year maintenance period, through 2031, and thereby 
satisfy the requirements for such a plan under CAA section 175A(b).

VII. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the Act and applicable 
Federal regulations. See 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, EPA's role is to approve state choices, 
provided that they meet the criteria of the CAA. This proposed action 
merely proposes to approve state law as meeting Federal requirements 
and does not impose additional requirements beyond those imposed by 
state law. For that reason, this proposed action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 12866 (58 
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     Does not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    The SIP is not approved to apply on any Indian reservation land or 
in any other area where EPA or an Indian tribe has demonstrated that a 
tribe has jurisdiction. In those areas of Indian country, the rule does 
not have tribal implications as specified by Executive Order 13175 (65 
FR 67249, November 9, 2000), nor will it impose substantial direct 
costs on tribal governments or preempt tribal law.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Nitrogen oxides, Ozone, 
Reporting and recordkeeping requirements, Volatile organic compounds.

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

    Dated: June 4, 2021.
John Blevins,
Acting Regional Administrator, Region 4.
[FR Doc. 2021-12164 Filed 6-10-21; 8:45 am]
BILLING CODE 6560-50-P