[Federal Register Volume 86, Number 182 (Thursday, September 23, 2021)]
[Proposed Rules]
[Pages 52864-52870]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-20349]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R04-OAR-2020-0428; FRL-8911-01-R4]


Air Plan Approval; TN; Montgomery County 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, on June 23, 2020. 
The SIP revision includes the 1997 8-hour ozone national ambient air 
quality standards (NAAQS) Limited Maintenance Plan (LMP) for the 
Montgomery County, Tennessee portion of the Clarksville-Hopkinsville 
Area (hereinafter referred to as the ``Montgomery County Area'' or 
``Area''). The Clarksville-Hopkinsville Area is comprised of Montgomery 
County, Tennessee, and Christian County, Kentucky. EPA is proposing to 
approve Tennessee's LMP for the Montgomery County Area because it 
provides for the maintenance of the 1997 8-hour ozone NAAQS within the 
Montgomery County 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 maintenance of the 1997 8-hour ozone 
NAAQS in the Montgomery County Area federally enforceable as part of 
the Tennessee SIP.

DATES: Comments must be received on or before October 25, 2021.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R04-
OAR-2020-0428 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
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 Montgomery County Area LMP for the 1997 8-hour ozone 
NAAQS, adopted by TDEC on June 10, 2020, and submitted by TDEC as a 
revision to the Tennessee SIP on June 23, 2020. In 2004, the Montgomery 
County Area was designated as nonattainment for the 1997 8-hour ozone 
NAAQS. Subsequently, in 2005, after having clean data and EPA's 
approval of a maintenance plan, the Area was redesignated to attainment 
for the 1997 8-hour ozone NAAQS. See 70 FR 55559 (September 22, 2005).
    The Montgomery County Area LMP, submitted by TDEC on June 23, 2020, 
is designed to maintain the 1997 8-hour ozone NAAQS within the 
Montgomery County 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 Montgomery County Area LMP relies on the 
same

[[Page 52865]]

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.\1\
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    \1\ See ``Fact Sheet, Proposal to Revise the National Ambient 
Air Quality Standards for Ozone,'' January 6, 2010 and 27 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).\2\ 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 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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    \2\ 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 Clarksville-
Hopkinsville Area, which included Montgomery County, Tennessee, and 
Christian County, Kentucky, 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 Montgomery County as unclassifiable/
attainment for the 2008 8-hour ozone NAAQS. This designation became 
effective on July 20, 2012. See 77 FR 30088 (May 21, 2012). In 
addition, on November 16, 2017, areas were designated for the 2015 8-
hour ozone NAAQS. The Montgomery County Area was designated attainment/
unclassifiable for the 2015 8-hour ozone NAAQS, with an effective date 
of January 16, 2018. See 82 FR 54232 (November 16, 2017).
    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.\3\ 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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    \3\ 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.\4\ 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 \5\ being significantly 
below the standard and the area having a historically stable design 
value.\6\ EPA refers to a maintenance plan containing this streamlined 
demonstration as an LMP.
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    \4\ 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).
    \5\ 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.
    \6\ See ``Limited Maintenance Plan Option for Nonclassifiable 
Ozone Nonattainment Areas,'' from Sally L. Shaver, OAQPS, November 
16, 1994; ``Limited Maintenance Plan Option for Nonclassifiable CO 
Nonattainment Areas,'' from Joseph Paisie, OAQPS, October 6, 1995; 
and ``Limited Maintenance Plan Option for Moderate PM10 
Nonattainment Areas,'' from Lydia Wegman, OAQPS, 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

[[Page 52866]]

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,\7\ EPA has extended the LMP interpretation of section 175A to 
other NAAQS and pollutants not specifically covered by the previous 
guidance memos.\8\
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    \7\ 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.
    \8\ 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 Clarksville-Hopkinsville 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 Montgomery County Area to fulfill the second 
maintenance plan requirement in the Act. EPA's evaluation of the 
Montgomery County Area's LMP is presented below.
    In August of 2005, TDEC submitted to EPA a request to redesignate 
the Montgomery County 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 Montgomery County through 2016 as a revision 
to the Tennessee SIP. EPA approved the Montgomery County Area's 
Maintenance Plan and the State's request to redesignate the Montgomery 
County Area to attainment for the 1997 8-hour ozone NAAQS, effective 
November 21, 2005. See 70 FR 55559 (September 22, 2005).
    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). See 80 FR 12264, 12315 (March 6, 2015).
    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 the 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 second maintenance period. 
Accordingly, on June 23, 2020, Tennessee submitted a second maintenance 
plan for the Montgomery County Area that shows that the Area is 
expected to remain in attainment of the 1997 8-hour ozone NAAQS through 
2025.
    In recognition of the continuing record of air quality monitoring 
data showing ambient 8-hour ozone concentrations in the Clarksville-
Hopkinsville Area well below the 1997 8-hour ozone NAAQS, TDEC chose 
the LMP option for the development of a second 1997 8-hour ozone NAAQS 
maintenance plan. On June 10, 2020, TDEC adopted the second 10-year 
1997 8-hour ozone maintenance plan, and on June 23, 2020, TDEC 
submitted the Montgomery County Area LMP to EPA as a revision to the 
Tennessee SIP.

III. Tennessee's SIP Submittal

    As mentioned above, on June 23, 2020, TDEC submitted the Montgomery 
County 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 the TDEC on June 10, 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 
for the Montgomery County Area is in response to the D.C. Circuit's 
decision overturning aspects of EPA's implementation rule for the 2008 
8-hour ozone NAAQS. The Montgomery County Area LMP does not include any 
additional emissions reduction measures but relies on the same emission 
reduction strategy as the first 10-year Maintenance Plan that provides 
for maintenance of the 1997 ozone NAAQS through 2016. The measures upon 
which the second 10-year LMP for the Montgomery County Area relies 
include the SIP-approved version of Tennessee Air Pollution Control 
Regulation 1200-03-27-.12, NOX SIP Call Requirements for 
Stationary Boilers and Combustion Turbines, which established a state 
control program for sources that are subject to the NOX SIP 
Call but not covered under Cross State Air Pollution Rule (CSAPR).\9\ 
The LMP also relies on continued implementation of federal measures 
(e.g., interstate transport rules such as CSAPR, see 76 FR 48208 
(August 8, 2011), and the CSAPR Update, see 81 FR 74504 (October 26, 
2016)).
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    \9\ See 86 FR 12092 (March 2, 2021).
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IV. EPA's Evaluation of Tennessee's SIP Submittal

    EPA has reviewed the Montgomery County Area's LMP which is designed 
to maintain the 1997 8-hour ozone NAAQS within Montgomery County 
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 \10\ and EPA's 
evaluation of how each requirement is met.
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    \10\ 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 VOCs and 
NOX, as these pollutants are precursors to ozone formation. 
The Montgomery County Area LMP includes an ozone attainment inventory 
for Montgomery County that reflects typical summer day emissions in 
2014. Table 1 presents a summary of the inventory for 2014 contained in 
the LMP.

[[Page 52867]]



     Table 1--2014 Typical Summer Day 8-Hour Ozone Emissions for the
                         Montgomery County Area
                            [Tons/summer day]
------------------------------------------------------------------------
                                                           NOX emissions
             Source category               VOC emissions
------------------------------------------------------------------------
Fire....................................          * 0.00          * 0.00
Nonpoint................................            8.79            0.90
Nonroad.................................            1.58            1.35
Onroad..................................            4.76            7.64
Point...................................            0.97            0.50
                                         -------------------------------
    Total...............................         * 16.10           10.39
------------------------------------------------------------------------
* This Total VOC Emissions value differs from Tennessee's submittal and
  has been re-calculated by TDEC to accurately reflect the total VOC
  emissions for Montgomery County.\11\

    The Emissions Inventory section of the Montgomery County 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).
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    \11\ See email from James Johnston, TDEC, to Lynorae Benjamin, 
EPA Region 4, on December 15, 2020, available in the docket for this 
proposed rulemaking.
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    Nonroad mobile source emissions in the 2014NEIv1, in part, were 
estimated using the latest version of the 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.\12\ Onroad mobile sources in the 2014NEIv1 were estimated 
using MOVES 2014a 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's set of estimates for vehicles 
reflects emissions inventories and ancillary data files used for 
emissions modeling, as well as the meteorological, initial condition, 
and boundary condition files needed to run the air quality model.
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    \12\ EPA developed emissions for these sectors based on AP-42 
emissions factor, 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 an 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.\13\ These criteria 
are evaluated below with regard to the Clarksville-Hopkinsville Area as 
a whole.
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    \13\ See footnote 4.
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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. 
There is currently one monitor measuring ozone, located within 
Christian County, Kentucky, which provides air quality data for the 
entire Clarksville-Hopkinsville Area. At the time of submission, EPA 
evaluated quality assured and certified 2016-2018 monitoring data \14\ 
and determined that the design value for the Clarksville-Hopkinsville 
Area was 0.060 ppm, or 71 percent of the level of the 1997 8-hour ozone 
NAAQS. Based on quality assured and certified monitoring data for 2018-
2020,\15\ the current design value for the Clarksville-Hopkinsville 
Area is 0.058 ppm, or 69 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.
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    \14\ See the spreadsheet titled ``Ozone Design Values, 2018 
(XLXS)'' at https://www.epa.gov/air-trends/air-quality-design-values#report.
    \15\ See the spreadsheet titled ``Ozone Design Values, 2020 
(XLXS)'' at https://www.epa.gov/air-trends/air-quality-design-values#report.
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    Tables 2a and 2b present the design values for the Clarksville-
Hopkinsville Area over the 2007-2020 period. As shown in Tables 2a and 
2b, the Hopkinsville monitor has been well 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.

[[Page 52868]]



 Table 2a--1997 8-Hour Ozone NAAQS Design Values (ppm) at the Monitoring Site in the Clarksville-Hopkinsville, TN-KY Area for the 2007-2013 Time Period
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                                                           AQS Site    2005-2007   2006-2008   2007-2009   2008-2010   2009-2011   2010-2012   2011-2013
           Location                  County        State      ID          DV          DV          DV          DV          DV          DV          DV
--------------------------------------------------------------------------------------------------------------------------------------------------------
Hopkinsville..................  Christian.......      KY  21-047-000       0.081       0.078     * 0.074       0.069       0.070       0.073       0.069
                                                                   6
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 Table 2b--1997 8-Hour Ozone NAAQS Design Values (ppm) at the Monitoring Site in the Clarksville-Hopkinsville, TN-KY Area for the 2014-2020 Time Period
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                                                           AQS Site    2012-2014   2013-2015   2014-2016   2015-2017   2016-2018   2017-2019   2018-2020
           Location                  County        State      ID          DV          DV          DV          DV          DV          DV          DV
--------------------------------------------------------------------------------------------------------------------------------------------------------
Hopkinsville..................  Christian.......      KY  21-047-000       0.067       0.063       0.062       0.061       0.060       0.058       0.058
                                                                   6
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* The Hopkinsville, KY site (AQS ID: 21-047-0006) was operated by the Tennessee Valley Authority (TVA) until 2008. In 2008, the Kentucky Division for
  Air Quality began operation of an ozone monitor at the site (designated in AQS as Parameter Occurrence Code (POC) 2), and TVA discontinued operation
  of its POC 1 ozone monitor at the end of 2008. Both monitors met completeness requirements for the years that they operated during 2007-2009. AQS does
  not combine data from different POCs when calculating a design value for the 1997 Ozone NAAQS. However, to accurately present the data in the Table, a
  2007-2009 design value was calculated using the combined datasets from the TVA and KY monitors. In 2008, when both monitors collected complete data,
  the KY monitor data was used because it is flagged as certified in AQS, while the 2008 TVA data is not. The combined 2007-2009 DV using 2007 data from
  the TVA monitor and 2008-2009 data from the KY monitor is 74 parts per billion and is shown in the Table.

    Therefore, the Montgomery County 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 Montgomery County 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.\16\ 
Those projections, made for the year 2023, show that the highest design 
value in the Clarksville-Hopkinsville Area is expected to be 0.056 ppm.
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    \16\ 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.
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2. Stability of Ozone Levels
    As discussed above, the Montgomery County Area has maintained air 
quality well below the 1997 8-hour ozone NAAQS over the past thirteen 
years. Additionally, the design value data shown within Tables 2a and 
2b illustrates that ozone levels have been relatively stable over this 
timeframe, with an overall downward trend. For example, the data within 
Tables 2a and 2b indicates that the largest year over year change in 
design value at any one monitor during these thirteen years was five 
parts per billion which occurred between the 2007-2009 design value and 
the 2008-2010 design value, and it represented only a six percent 
change. Furthermore, the overall trend in design values for the 
Clarksville-Hopkinsville Area between 2007-2020 shows a decrease of 23 
parts per billion at the Hopkinsville monitor (AQS Site ID 21-047-
0006). 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 Montgomery County 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 
10-year maintenance period. TDEC provided a VOC and NOx emissions 
trends analysis from 2014 to 2028. Tennessee selected 2014 as a 
baseline for the projection because that is the most recent year for 
which a complete set of data was available from EPA's National 
Emissions Inventory (NEI) database at the time the State developed its 
second maintenance plan for the Area.\17\ Projected emissions data for 
the year 2028 were obtained from EPA,\18\ and these data represent EPA 
emissions projections that are available for a date furthest out into 
the future.\19\ The emissions projection trends show that between 2014 
and 2028, VOC emissions are estimated to fall by approximately 43 
percent, and NOx emissions are estimated to fall by approximately 56 
percent within the Montgomery County Area. These projected declining 
emissions trends further support the conclusion that it is unlikely 
that the Area would violate the 1997 8-hour ozone NAAQS in the future. 
Table 3 presents a summary of projected emissions for 2028 contained in 
the maintenance plan.
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    \17\ The 2017 NEI is the most recent NEI, but it was unavailable 
to Tennessee when the State developed its SIP revision.
    \18\ The projected emissions data is available at https://www.epa.gov/air-emissions-modeling/2014-2016-version-7-air-emissions-modeling-platforms.
    \19\ 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.

     Table 3--2028 Typical Summer Day 8-Hour Ozone Emissions for the
                         Montgomery County Area
                               [tons/day]
------------------------------------------------------------------------
                                                           NOX emissions
             Source category               VOC emissions
------------------------------------------------------------------------
Fire....................................            0.58            0.02
Nonpoint................................            5.31            1.36

[[Page 52869]]

 
Nonroad.................................            1.12            0.67
Onroad..................................            1.43            2.15
Point...................................            0.73            0.31
                                         -------------------------------
    Total...............................            9.17            4.51
------------------------------------------------------------------------

C. Monitoring Network and Verification of Continued Attainment

    EPA periodically reviews the ozone monitoring network that the 
Commonwealth of Kentucky operates and maintains in Christian County, in 
accordance with 40 CFR part 58. This network plan, which is submitted 
annually to EPA, is consistent with the ambient air monitoring network 
assessment. The annual network plan developed by the Kentucky Division 
for Air Quality (KDAQ) follows a public notification and review 
process. EPA has reviewed and approved the 2020 Ambient Air Monitoring 
Network Plan (``2020 Annual Network Plan'').\20\
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    \20\ Kentucky's network plan is available at https://www.tn.gov/content/dam/tn/environment/air/documents/apcairqualitymonitoring/2020%20Tennessee%20Annual%20Monitoring%20Network%20Plan%20-%20Comment%20Update.pdf.
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    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, KDAQ's monitoring 
network in the Clarksville-Hopkinsville Area has been approved by EPA 
in accordance with 40 CFR part 58, and Kentucky committed, in its SIP-
approved maintenance plan,\21\ to continue to maintain a network in 
accordance with EPA requirements. TDEC supports continued ozone 
monitoring by KDAQ. EPA proposes to find that KDAQ's monitoring network 
is adequate to verify continued attainment of the 1997 8-hour ozone 
NAAQS in the Montgomery County Area.
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    \21\ See 71 FR 4047 (January 25, 2006).
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D. Contingency Plan

    Section 175A(d) of the Act 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 Clarksville-Hopkinsville Area.\22\ 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.\23\
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    \22\ 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 event will not have occurred, and contingency measures 
will not need to be implemented.
    \23\ 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.
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    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 Montgomery County 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 Montgomery 
County 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 well below the 
NAAQS and historically stable design values. EPA believes the 
Montgomery County 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 Montgomery County over the second 
maintenance period (i.e., through 2025) and thereby satisfies the 
requirements for such a plan under CAA section 175A(b). EPA is 
therefore proposing to approve Tennessee's June 23, 2020, submission of 
the Montgomery County Area's LMP as a revision to the Tennessee SIP.

V. Transportation 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 vehicle 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,

[[Page 52870]]

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 22, 2005, EPA made a finding that the MVEBs for the first 12 
years of the 1997 8-hour ozone maintenance plan for the Montgomery 
County Area were adequate for transportation conformity purposes. In a 
Federal Register notice dated September 22, 2005, EPA notified the 
public of that finding. See 70 FR 55559. These new MVEBs became 
effective November 21, 2005. 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 Montgomery County 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 the LMP. See 69 FR 
40004 (July 1, 2004).
    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).\24\ 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.
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    \24\ 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.
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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 Montgomery County Area LMP 
for the 1997 8-hour ozone NAAQS, submitted by TDEC on June 23, 2020, as 
a revision to the Tennessee SIP. EPA is proposing to approve the 
Montgomery County 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 Montgomery County Area qualifies for the 
LMP option and that, therefore, the Montgomery County 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 that the Montgomery County Area's 1997 8-Hour 
Ozone LMP is sufficient to provide for maintenance of the 1997 8-hour 
ozone NAAQS in Montgomery County over the second 10-year maintenance 
period, through 2025, 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 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: September 1, 2021.
John Blevins,
Acting Regional Administrator, Region 4.
[FR Doc. 2021-20349 Filed 9-22-21; 8:45 am]
BILLING CODE 6560-50-P