[Federal Register Volume 83, Number 126 (Friday, June 29, 2018)]
[Proposed Rules]
[Pages 30609-30622]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-14097]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R04-OAR-2017-0626; FRL-9980-18-Region 4]


Air Plan Approval; Tennessee; Attainment Plan for Sullivan County 
SO2 Nonattainment Area

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), to EPA on May 12, 2017, for attaining the 2010 1-
hour sulfur dioxide (SO2) primary national ambient air 
quality standard (NAAQS) for the Sullivan County SO2 
nonattainment area (hereafter referred to as the ``Sullivan County 
Area'' or ``Area''). The Sullivan County Area is comprised of a portion 
of Sullivan County in Tennessee surrounding the Eastman Chemical 
Company (hereafter referred to as ``Eastman''). This plan (herein 
called a ``nonattainment plan or SIP'' or ``attainment plan or SIP'') 
includes Tennessee's attainment demonstration and other elements 
required under the Clean Air Act (CAA or Act). In addition to an 
attainment demonstration, the plan addresses the requirement for 
meeting reasonable further progress (RFP) toward attainment of the 
NAAQS, reasonably available control measures and reasonably available 
control technology (RACM/RACT), base-year and projection-year emissions 
inventories, enforceable emissions limitations and control measures, 
and contingency measures. EPA proposes to conclude that Tennessee has 
appropriately demonstrated that the plan's provisions provide for 
attainment of the 2010 1-hour primary SO2 NAAQS in the 
Sullivan County Area and that the plan meets the other applicable 
requirements under the CAA.

DATES: Comments must be received on or before July 30, 2018.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R04-
OAR-2017-0626 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: D. Brad Akers, Air Regulatory 
Management Section, Air Planning and Implementation Branch, Air, 
Pesticides and Toxics Management Division, U.S. Environmental 
Protection Agency, Region 4, 61 Forsyth Street SW, Atlanta, Georgia 
30303-8960. Mr. Akers can be reached via telephone at (404) 562-9089 or 
via electronic mail at [email protected].

SUPPLEMENTARY INFORMATION:

I. Requirement for Tennessee to Submit an SO2 Attainment 
Plan for the Sullivan County Area

[[Page 30610]]

II. Requirements for SO2 Attainment Plans
III. Attainment Demonstration and Longer Term Averaging
IV. Review of Attainment Plan Requirements
    A. Emissions Inventory
    B. Attainment Modeling Demonstration
    1. Model Selection
    2. Meteorological Data
    3. Emissions Data
    4. Emission Limits
    i. Enforceability
    ii. Longer Term Average Limits
    5. Background Concentration
    6. Analysis of Multi-Stack Limit
    7. Summary of Modeling Results
    C. RACM/RACT
    D. New Source Review (NSR)
    E. Reasonable Further Progress (RFP)
    F. Contingency Measures
V. Additional Elements of Tennessee's Submittal
VI. Incorporation by Reference
VII. EPA's Proposed Action
VIII. Statutory and Executive Orders

I. Requirement for Tennessee To Submit an SO2 Attainment Plan for the 
Sullivan County Area

    On June 22, 2010, EPA promulgated a new 1-hour primary 
SO2 NAAQS of 75 parts per billion (ppb), which is met at an 
ambient air quality monitoring site when the 3-year average of the 
annual 99th percentile of daily maximum 1-hour average concentrations 
does not exceed 75 ppb, as determined in accordance with appendix T of 
40 CFR part 50. See 75 FR 35520, codified at 40 CFR 50.17(a)-(b). On 
August 5, 2013, EPA designated a first set of 29 areas of the country 
as nonattainment for the 2010 SO2 NAAQS. See 78 FR 47191, 
codified at 40 CFR part 81, subpart C. These designations included the 
Sullivan County Area, which encompasses the primary SO2 
emitting source Eastman and the nearby SO2 monitor (Air 
Quality Site ID: 47-163-0007). These area designations were effective 
October 4, 2013. Section 191(a) of the CAA directs states to submit 
SIPs for areas designated as nonattainment for the SO2 NAAQS 
to EPA within 18 months of the effective date of the designation, i.e., 
by no later than April 4, 2015 in this case. Under CAA section 192(a) 
these SIPs are required to demonstrate that their respective areas will 
attain the NAAQS as expeditiously as practicable, but no later than 5 
years from the effective date of designation, which is October 4, 2018. 
In addition, sections 110(a) and 172(c), as well as EPA regulations at 
40 CFR part 51, set forth substantive elements each SIP must contain to 
be approved by EPA.
    For the Sullivan County Area (and many other areas), EPA published 
a notice on March 18, 2016, that Tennessee (and other pertinent states) 
had failed to submit the required SO2 nonattainment plan by 
this submittal deadline. See 81 FR 14736. This finding initiated a 
deadline under CAA section 179(a) for the potential imposition of new 
source review and highway funding sanctions. However, pursuant to 
Tennessee's submittal of May 12, 2017, and EPA's subsequent letter 
dated October 10, 2017, to Tennessee finding the submittal complete and 
noting the termination of these sanctions deadlines, these sanctions 
under section 179(a) will not be imposed as a result of Tennessee 
having missed the April 4, 2015 deadline. Under CAA section 110(c), the 
March 18, 2016 finding also triggered a requirement that EPA promulgate 
a federal implementation plan (FIP) within two years of the finding 
unless (a) the state has made the necessary complete submittal and (b) 
EPA has approved the submittal as meeting applicable requirements.

II. Requirements for SO2 Attainment Plans

    To be approved by EPA, nonattainment areas must provide SIPs 
meeting the applicable requirements of the CAA, and specifically CAA 
sections 110(a), 172, 191 and 192 for SO2. EPA's regulations 
governing nonattainment SIPs are set forth at 40 CFR part 51, with 
specific procedural requirements and control strategy requirements 
residing at subparts F and G, respectively. Soon after Congress enacted 
the 1990 Amendments to the CAA, EPA issued comprehensive guidance on 
SIPs, in a document entitled the ``General Preamble for the 
Implementation of Title I of the Clean Air Act Amendments of 1990,'' 
published at 57 FR 13498 (April 16, 1992) (General Preamble). Among 
other things, the General Preamble addressed SO2 SIPs and 
fundamental principles for SIP control strategies. Id., at 13545-49, 
13567-68. On April 23, 2014, EPA issued recommended guidance for 
meeting the statutory requirements in SO2 SIPs under the 
2010 revised NAAQS, in a document entitled, ``Guidance for 1-Hour 
SO2 Nonattainment Area SIP Submissions,'' available at 
https://www.epa.gov/sites/production/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf (hereafter referred to as EPA's 
April 2014 SO2 guidance or guidance). In this guidance EPA 
described the statutory requirements for SO2 SIPs for 
nonattainment areas, which includes: An accurate emissions inventory of 
current emissions for all sources of SO2 within the 
nonattainment area; an attainment demonstration; demonstration of RFP; 
implementation of RACM (including RACT); new source review (NSR); 
enforceable emissions limitations and control measures; and adequate 
contingency measures for the affected area.
    For EPA to fully approve a SIP as meeting the requirements of CAA 
sections 110, 172 and 191-192, and EPA's regulations at 40 CFR part 51, 
the SIP for the affected area needs to demonstrate to EPA's 
satisfaction that each of the aforementioned requirements have been 
met. Under CAA sections 110(l) and 193, EPA may not approve a SIP that 
would interfere with any applicable requirement concerning NAAQS 
attainment and RFP, or any other applicable requirement, and no 
requirement in effect (or required to be adopted by an order, 
settlement, agreement, or plan in effect before November 15, 1990) in 
any area which is a nonattainment area for any air pollutant, may be 
modified in any manner unless it insures equivalent or greater emission 
reductions of such air pollutant.

III. Attainment Demonstration and Longer Term Averaging

    CAA sections 172(c)(1) and (6) direct states with areas designated 
as nonattainment to demonstrate that the submitted plan provides for 
attainment of the NAAQS. 40 CFR part 51, subpart G further delineates 
the control strategy requirements that SIPs must meet, and EPA has long 
required that all SIPs and control strategies reflect four fundamental 
principles of quantification, enforceability, replicability, and 
accountability. General Preamble, at 13567-68. SO2 
attainment plans must consist of two components: (1) Emission limits 
and other control measures that assure implementation of permanent, 
enforceable and necessary emission controls, and (2) a modeling 
analysis which meets the requirements of 40 CFR part 51, appendix W 
which demonstrates that these emission limits and control measures 
provide for timely attainment of the primary SO2 NAAQS as 
expeditiously as practicable, but by no later than the attainment date 
for the affected area. In all cases, the emission limits and control 
measures must be accompanied by appropriate methods and conditions to 
determine compliance with the respective emission limits and control 
measures and must be quantifiable (i.e., a specific amount of emission 
reduction can be ascribed to the measures), fully-enforceable 
(specifying clear, unambiguous and measurable requirements for which 
compliance can be practicably determined), replicable (the procedures 
for determining compliance are

[[Page 30611]]

sufficiently specific and non-subjective so that two independent 
entities applying the procedures would obtain the same result), and 
accountable (source specific limits must be permanent and must reflect 
the assumptions used in the SIP demonstrations).
    EPA's April 2014 SO2 guidance recommends that the 
emission limits be expressed as short-term average limits (e.g., 
addressing emissions averaged over one or three hours), but also 
describes the option to utilize emission limits with longer averaging 
times of up to 30 days so long as the state meets various suggested 
criteria. See EPA's April 2014 SO2 guidance, pp. 22 to 39. 
The guidance recommends that--should states and sources utilize longer 
averaging times--the longer term average limit should be set at an 
adjusted level that reflects a stringency comparable to the 1-hour 
average limit at the critical emission value (CEV) shown by modeling to 
provide for attainment that the plan otherwise would have set.
    EPA's April 2014 SO2 guidance provides an extensive 
discussion of EPA's rationale for concluding that appropriately set 
comparably stringent limitations based on averaging times as long as 30 
days can be found to provide for attainment of the 2010 SO2 
NAAQS. In evaluating this option, EPA considered the nature of the 
standard, conducted detailed analyses of the impact of use of 30-day 
average limits on the prospects for attaining the standard, and 
carefully reviewed how best to achieve an appropriate balance among the 
various factors that warrant consideration in judging whether a state's 
plan provides for attainment. Id. at pp. 22 to 39. See also id. at 
Appendices B, C, and D.
    As specified in 40 CFR 50.17(b), the 1-hour primary SO2 
NAAQS is met at an ambient air quality monitoring site when the 3-year 
average of the annual 99th percentile of daily maximum 1-hour average 
concentrations is less than or equal to 75 ppb. In a year with 365 days 
of valid monitoring data, the 99th percentile would be the fourth 
highest daily maximum 1-hour value. The 2010 SO2 NAAQS, 
including this form of determining compliance with the standard, was 
upheld by the U.S. Court of Appeals for the District of Columbia 
Circuit in Nat'l Envt'l Dev. Ass'n's Clean Air Project v. EPA, 686 F.3d 
803 (D.C. Cir. 2012). Because the standard has this form, a single 
hourly exceedance of the 75-ppb level does not create a violation of 
the standard. Instead, at issue is whether a source operating in 
compliance with a properly set longer term average could cause hourly 
exceedances of the NAAQS level, and if so the resulting frequency and 
magnitude of such exceedances, and in particular whether EPA can have 
reasonable confidence that a properly set longer term average limit 
will provide that the 3-year average of the annual fourth highest daily 
maximum 1-hour value will be at or below 75 ppb. A synopsis of how EPA 
judges whether such plans ``provide for attainment,'' based on modeling 
of projected allowable emissions and in light of the NAAQS's form for 
determining attainment at monitoring sites, follows.
    For SO2 plans that are based on 1-hour emission limits, 
the standard approach is to conduct modeling using fixed emission 
rates. The maximum emission rate that would be modeled to result in 
attainment (i.e., in an ``average year'' \1\ shows three, not four days 
with maximum hourly levels exceeding 75 ppb) is labeled the ``critical 
emission value.'' The modeling process for identifying this critical 
emissions value inherently considers the numerous variables that affect 
ambient concentrations of SO2, such as meteorological data, 
background concentrations, and topography. In the standard approach, 
the state would then provide for attainment by setting a continuously 
applicable 1-hour emission limit at this critical emission value.
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    \1\ An ``average year'' is used to mean a year with average air 
quality. While 40 CFR 50 appendix T provides for averaging three 
years of 99th percentile daily maximum hourly values (e.g., the 
fourth highest maximum daily hourly concentration in a year with 365 
days with valid data), this discussion and an example below uses a 
single ``average year'' to simplify the illustration of relevant 
principles.
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    EPA recognizes that some sources have highly variable emissions, 
for example due to variations in fuel sulfur content and operating 
rate, that can make it extremely difficult, even with a well-designed 
control strategy, to ensure in practice that emissions for any given 
hour do not exceed the critical emission value. EPA also acknowledges 
the concern that longer term emission limits can allow short periods 
with emissions above the ``critical emissions value,'' which, if 
coincident with meteorological conditions conducive to high 
SO2 concentrations, could in turn create the possibility of 
a NAAQS exceedance occurring on a day when an exceedance would not have 
occurred if emissions were continuously controlled at the level 
corresponding to the critical emission value. However, for several 
reasons, EPA believes that the approach recommended in its guidance 
document suitably addresses this concern. First, from a practical 
perspective, EPA expects the actual emission profile of a source 
subject to an appropriately set longer term average limit to be similar 
to the emission profile of a source subject to an analogous 1-hour 
average limit. EPA expects this similarity because it has recommended 
that the longer term average limit be set at a level that is comparably 
stringent to the otherwise applicable 1-hour limit (reflecting a 
downward adjustment from the critical emissions value) and that takes 
the source's emissions profile into account. As a result, EPA expects 
either form of emission limit to yield comparable air quality.
    Second, from a more theoretical perspective, EPA has compared the 
likely air quality with a source having maximum allowable emissions 
under an appropriately set longer term limit, as compared to the likely 
air quality with the source having maximum allowable emissions under 
the comparable 1-hour limit. In this comparison, in the 1-hour average 
limit scenario, the source is presumed at all times to emit at the 
critical emission level, and in the longer term average limit scenario 
the source is presumed to occasionally emit more than the critical 
emission value but on average, and presumably at most times, to emit 
well below the critical emission value. In an ``average year,'' 
compliance with the 1-hour limit is expected to result in three 
exceedance days (i.e., three days with hourly values above 75 ppb) and 
a fourth day with a maximum hourly value at 75 ppb. By comparison, with 
the source complying with a longer term limit, it is possible that 
additional exceedances would occur that would not occur in the 1-hour 
limit scenario (if emissions exceed the critical emission value at 
times when meteorology is conducive to poor air quality). However, this 
comparison must also factor in the likelihood that exceedances that 
would be expected in the 1-hour limit scenario would not occur in the 
longer term limit scenario. This result arises because the longer term 
limit requires lower emissions most of the time (because the limit is 
set well below the critical emission value), so a source complying with 
an appropriately set longer term limit is likely to have lower 
emissions at critical times than would be the case if the source were 
emitting as allowed with a 1-hour limit.
    As a hypothetical example to illustrate these points, suppose a 
source that always emits 1,000 pounds of SO2 per hour, which 
results in air quality at the level of the NAAQS (i.e., results in a 
design value of 75 ppb). Suppose further that in an ``average year,'' 
these emissions cause the 5-highest maximum

[[Page 30612]]

daily average 1-hour concentrations to be 100 ppb, 90 ppb, 80 ppb, 75 
ppb, and 70 ppb. Then suppose that the source becomes subject to a 30-
day average emission limit of 700 pounds per hour (lbs/hr). It is 
theoretically possible for a source meeting this limit to have 
emissions that occasionally exceed 1,000 pounds per hour, but with a 
typical emissions profile, emissions would much more commonly be 
between 600 and 800 lbs/hr. In this simplified example, assume a zero-
background concentration, which allows one to assume a linear 
relationship between emissions and air quality. (A nonzero background 
concentration would make the mathematics more difficult but would give 
similar results.) Air quality will depend on what emissions happen on 
what critical hours, but suppose that emissions at the relevant times 
on these 5 days are 800 lbs/hr, 1,100 lbs/hr, 500 lbs/hr, 900 lbs/hr, 
and 1,200 lbs/hr, respectively. (This is a conservative example because 
the average of these emissions, 900 lbs/hr, is well over the 30-day 
average emission limit.) These emissions would result in daily maximum 
1-hour concentrations of 80 ppb, 99 ppb, 40 ppb, 67.5 ppb, and 84 ppb. 
In this example, the fifth day would have an exceedance that would not 
otherwise have occurred, but the third and fourth days would not have 
exceedances that otherwise would have occurred. In this example, the 
fourth highest maximum daily concentration under the 30-day average 
would be 67.5 ppb.
    This simplified example illustrates the findings of a more 
complicated statistical analysis that EPA conducted using a range of 
scenarios using actual plant data. As described in Appendix B of EPA's 
April 2014 SO2 guidance, EPA found that the requirement for 
lower average emissions is highly likely to yield better air quality 
than is required with a comparably stringent 1-hour limit. Based on 
analyses described in appendix B of its 2014 guidance, EPA expects that 
an emission profile with maximum allowable emissions under an 
appropriately set comparably stringent 30-day average limit is likely 
to have the net effect of having a lower number of exceedances and 
better air quality than an emission profile with maximum allowable 
emissions under a 1-hour emission limit at the critical emission value. 
This result provides a compelling policy rationale for allowing the use 
of a longer averaging period, in appropriate circumstances where the 
facts indicate this result can be expected to occur.
    The question then becomes whether this approach--which is likely to 
produce a lower number of overall exceedances even though it may 
produce some unexpected exceedances above the critical emission value--
meets the requirements in sections 110(a)(1) and (2), 172(c)(1) and (6) 
for SIPs to contain enforceable emissions limitations and other control 
measures to ``provide for attainment'' of the NAAQS. For 
SO2, as for other pollutants, it is generally impossible to 
design a nonattainment plan in the present that will guarantee that 
attainment will occur in the future. A variety of factors can cause a 
well-designed attainment plan to fail and unexpectedly not result in 
attainment, for example if meteorology occurs that is more conducive to 
poor air quality than was anticipated in the plan. Therefore, in 
determining whether a plan meets the requirement to provide for 
attainment, EPA's task is commonly to judge not whether the plan 
provides absolute certainty that attainment will in fact occur, but 
rather whether the plan provides an adequate level of confidence of 
prospective NAAQS attainment. From this perspective, in evaluating use 
of a 30-day average limit, EPA must weigh the likely net effect on air 
quality. Such an evaluation must consider the risk that occasions with 
meteorology conducive to high concentrations will have elevated 
emissions leading to exceedances that would not otherwise have 
occurred, and must also weigh the likelihood that the requirement for 
lower emissions on average will result in days not having exceedances 
that would have been expected with emissions at the critical emissions 
value. Additional policy considerations, such as in this case the 
desirability of accommodating real world emissions variability without 
significant risk of violations, are also appropriate factors for EPA to 
weigh in judging whether a plan provides a reasonable degree of 
confidence that the plan will lead to attainment. Based on these 
considerations, especially given the high likelihood that a 
continuously enforceable limit averaged over as long as 30 days, 
determined in accordance with EPA's guidance, will result in 
attainment, EPA believes as a general matter that such limits, if 
appropriately determined, can reasonably be considered to provide for 
attainment of the 2010 SO2 NAAQS.
    The April 2014 SO2 guidance offers specific 
recommendations for determining an appropriate longer term average 
limit. The recommended method starts with determination of the 1-hour 
emission limit that would provide for attainment (i.e., the critical 
emission value), and applies an adjustment factor to determine the 
(lower) level of the longer term average emission limit that would be 
estimated to have a degree of stringency comparable to the otherwise 
necessary 1-hour emission limit. This method uses a database of 
continuous emission data reflecting the type of control that the source 
will be using to comply with the SIP emission limits, which (if 
compliance requires new controls) may require use of an emission 
database from another source. The recommended method involves using 
these data to compute a complete set of emission averages, computed 
according to the averaging time and averaging procedures of the 
prospective emission limitation. In this recommended method, the ratio 
of the 99th percentile among these long term averages to the 99th 
percentile of the 1-hour values represents an adjustment factor that 
may be multiplied by the candidate 1-hour emission limit to determine a 
longer term average emission limit that may be considered comparably 
stringent.\2\ The guidance also addresses a variety of related topics, 
such as the potential utility of setting supplemental emission limits, 
such as mass-based limits, to reduce the likelihood and/or magnitude of 
elevated emission levels that might occur under the longer term 
emission rate limit.
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    \2\ For example, if the critical emission value is 1,000 pounds 
of SO2 per hour, and a suitable adjustment factor is 
determined to be 70 percent, the recommended longer term average 
limit would be 700 lbs/hr.
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    Preferred air quality models for use in regulatory applications are 
described in Appendix A of EPA's Guideline on Air Quality Models (40 
CFR part 51, appendix W). In 2005, EPA promulgated AERMOD as the 
Agency's preferred near-field dispersion modeling for a wide range of 
regulatory applications addressing stationary sources (for example in 
estimating SO2 concentrations) in all types of terrain based 
on extensive developmental and performance evaluation. Supplemental 
guidance on modeling for purposes of demonstrating attainment of the 
SO2 NAAQS is provided in appendix A to the April 2014 
SO2 guidance document referenced above. Appendix A provides 
extensive guidance on the modeling domain, the source inputs, assorted 
types of meteorological data, and background concentrations. 
Consistency with the recommendations in this guidance is generally 
necessary for the attainment demonstration to offer

[[Page 30613]]

adequately reliable assurance that the plan provides for attainment.
    As stated previously, attainment demonstrations for the 2010 1-hour 
primary SO2 NAAQS must demonstrate future attainment and 
maintenance of the NAAQS in the entire area designated as nonattainment 
(i.e., not just at the violating monitor) by using air quality 
dispersion modeling (see appendix W to 40 CFR part 51) to show that the 
mix of sources and enforceable control measures and emission rates in 
an identified area will not lead to a violation of the SO2 
NAAQS. For a short-term (i.e., 1-hour) standard, EPA believes that 
dispersion modeling, using allowable emissions and addressing 
stationary sources in the affected area (and in some cases sources 
located outside the nonattainment area which may affect attainment in 
the area) is technically appropriate, efficient and effective in 
demonstrating attainment in nonattainment areas because it takes into 
consideration combinations of meteorological and emission source 
operating conditions that may contribute to peak ground-level 
concentrations of SO2.
    The meteorological data used in the analysis should generally be 
processed with the most recent version of AERMET. Estimated 
concentrations should include ambient background concentrations, should 
follow the form of the NAAQS, and should be calculated as described in 
section 2.6.1.2 of the August 23, 2010 clarification memo on 
``Applicability of appendix W Modeling Guidance for the 1-hr 
SO2 National Ambient Air Quality Standard'' (U.S. EPA, 
2010a).

IV. Review of Attainment Plan Requirements

A. Emissions Inventory

    The emissions inventory and source emission rate data for an area 
serve as the foundation for air quality modeling and other analyses 
that enable states to: (1) Estimate the degree to which different 
sources within a nonattainment area contribute to violations within the 
affected area; and (2) assess the expected improvement in air quality 
within the nonattainment area due to the adoption and implementation of 
control measures. As noted above, the State must develop and submit to 
EPA a comprehensive, accurate and current inventory of actual emissions 
from all sources of SO2 emissions in each nonattainment 
area, as well as any sources located outside the nonattainment area 
which may affect attainment in the area. See CAA section 172(c)(3).
    The primary SO2-emitting point source located within the 
Sullivan County Area is Eastman, which produces organic acids, 
aldehydes, esters, polymers, cellulose esters, specialty plastics, and 
acetate fibers. The facility also produces process steam and 
electricity for most of the operations, including hazardous waste 
combustion, and wastewater treatment. Eastman consists of three main 
SO2 emitting sources comprised of three powerhouses that 
include a total of 14 boilers and several smaller emitters:
     Powerhouse B-83 consists of Boilers 18-24, denoted B-18--
B-24, which fire coal to provide steam for facility operations. Each of 
the seven emissions units has the following capacities: Boilers B-18--
B-20 are rated at 246 million British thermal units per hour (MMBtu/
hr); Boilers B-21--B-22 have a rated capacity of 249 MMBtu/hr; and 
Boilers B-23--B-24 have a rated capacity of 501 MMBtu/hr. All seven B-
83 boilers have existing limits on SO2 emissions of 2.4 lbs/
MMBtu based on a 1-hour averaging period. Actual emissions from B-83 
were 5,686 tons per year (tpy) in 2011.
     Powerhouse B-253 consists of units B-25--B-29 which fire 
coal to provide steam for facility operations. Each emissions unit, B-
25--B-29 has a rated capacity of 655 MMBtu/hr and an existing limit on 
SO2 emissions of 2.4 lbs/MMBtu based on a 24-hour averaging 
period. The B-253 powerhouse is currently undergoing a multi-year 
project to convert the power generation from the coal-fired boilers to 
natural gas-fired boilers to comply with regional haze best available 
retrofit technology (BART). See section IV.B.4.i for additional BART 
discussion. The result will be that the emissions units B-25--B-29 will 
fire only natural gas as repowered units start up and for all units no 
later than the attainment date for the 1-hour SO2 NAAQS, 
October 4, 2018.\3\ Actual emissions from B-253 were 14,897 tpy in 
2011.
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    \3\ As mentioned elsewhere in this proposed action, four boilers 
have converted to exclusive use of natural gas for fuel combustion 
already. These repowered units have different heat capacities, and 
the fuel content is such that the actual emissions of SO2 
will always be much less than the formerly permitted rate.
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     Powerhouse B-325 consists of Boilers B-30 and B-31, which 
fire coal to provide steam for facility operations. Boiler B-30 has a 
rated capacity of 780 MMBtu/hr and an existing emission limit on 
SO2 emissions of 317 lbs/hr based on a 30-day averaging 
period, equivalent to 0.406 lbs/MMBtu. Boiler B-31 is rated at 880 
MMBtu/hr and has an existing limit on SO2 emissions of 293 
lbs/hr based on a 30-day averaging period, equivalent to 0.333 lbs/
MMBtu. Actual emissions from B-325 were 1,276 tpy in 2011.
     The B-248 unit consists of three hazardous waste 
combustors, one liquid chemical waste incinerator and two rotary kilns 
that can burn solid or liquid chemical waste, B-248-2, Vent A, and B-
248-1, Vents D and E, respectively. According to the attainment SIP 
submitted by TDEC in May 2017, each of these units is subject to an 
existing limit on SO2 emissions for an exhaust concentration 
of 1,000 parts per million by volume SO2, equivalent to 
1,109 tpy for B-248-2, Vent A, and 1,552 tpy each for 248-1, Vents D 
and E. Actual emissions from B-248 were 7.3 tpy in 2011. On February 1, 
2018, TDEC issued a revised title V permit (568496) that included 
additional SO2 limits of 20 tpy for Vent A and 40 tpy for 
Vents D and E, combined.
     Eastman has 31 other smaller emission units that provide 
various services to other parts of the facility, and these units 
account for 194.56 tpy of the allowable emissions across the facility. 
Actual emissions from the remaining units were 40.9 tpy in 2011. For 
more information on these miscellaneous units, see the May 12, 2017, 
submittal.
    The emissions at units for Eastman were recorded either by using 
data collected from CEMS or by material balances based on feed rates 
and other parameters and are quality-assured by TDEC.\4\
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    \4\ As detailed in Section IV. of this proposed action, CEMS 
will be installed for Powerhouse B-83. Therefore, all subsequent 
emissions inventories and all compliance assessments will be based 
on CEMS measurements.
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    The next largest SO2 source within the nonattainment 
area is the EnviraGlass, LLC glass manufacturing facility 
(EnviraGlass). SO2 emissions from EnviraGlass were 49.3 tons 
in 2011, as determined from material balances. The EnviraGlass 
Kingsport facility consists of one main SO2 emitter. The 
glass melting furnace #1 (GMF-1) fires natural gas and No. 2 fuel oil. 
The allowable permit limit for EnviraGlass of 39.6 lb/hr was included 
in the attainment modeling.
    The next largest SO2 source in Sullivan County is 
located just outside the Sullivan County Area boundary: Domtar Paper 
Company, LLC, Kingsport Paper Mill (Domtar). Domtar produces pulp and 
paper and is permitted to burn hog fuel, dry wood residue, engineered 
fuel, wastewater treatment plant sludge, fuel oil, and natural gas. 
SO2 emissions from this facility were 70.8 tons in 2011, as 
determined from material balances.

[[Page 30614]]

The permitted allowable SO2 emissions limit for the main 
SO2 emissions unit at Domtar, the HFB1-1 biomass boiler, was 
included in the attainment modeling (264 lb/hr = 33.26 g/s). TDEC 
determined that the other SO2 emissions units at Domtar did 
not need to be explicitly modeled because of their smaller emissions 
levels. Therefore, these sources were accounted for using the 
background concentration discussed in section IV.B.5 of this notice.
    TDEC utilized EPA's 2011 National Emissions Inventory (NEI), 
Version 2 as the starting point for compiling point source emissions 
for the base year emissions inventory. The hazardous waste incinerators 
at Eastman in B-248 were erroneously reported as 20 tpy each for B-248-
1 and B-248-2. TDEC corrected this information from the 2011 NEI with 
information submitted by Eastman.\5\ EnviraGlass, formerly Heritage 
Glass, did not report emissions for the 2011 NEI, so TDEC used 
semiannual compliance reports pursuant to the title V operating permit 
for the facility to determine emissions.
---------------------------------------------------------------------------

    \5\ For more information on this correction to the 2011 NEI, 
Version 2 emissions, see Attachment A of Tennessee's May 12, 2017, 
submittal.
---------------------------------------------------------------------------

    TDEC also used the 2011 NEI, Version 2 to obtain estimates of the 
area and nonroad sources. For onroad mobile source emissions, TDEC 
utilized EPA's Motor Vehicle Emissions Simulator (MOVES2014). A more 
detailed discussion of the emissions inventory development for the 
Sullivan County Area can be found in Tennessee's May 12, 2017, 
submittal.
    Table 1 below shows the level of emissions, expressed in tpy, in 
the Sullivan County Area for the 2011 base year by emissions source 
category. The point source category includes all sources within the 
nonattainment area.

                                        Table 1--2011 Base Year Emissions Inventory for the Sullivan County Area
                                                                          [tpy]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                Year                                      Point            Onroad          Nonroad            Area            Total
--------------------------------------------------------------------------------------------------------------------------------------------------------
2011...............................................................        21,956.5             1.62             0.16             10.6        21,968.88
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Domtar is not included in the base year inventory for the Sullivan 
County Area because it is outside of the boundary of the nonattainment 
area. However, TDEC evaluated 2011 emissions from this facility to 
evaluate its impact on the area. Domtar's emissions were reported for 
the 2011 NEI, but TDEC determined that emissions from HFB1-1, the 
biomass boiler, were initially reported in error as 2.06 tons. Actual 
emissions were determined from fuel usage data supplied by Domtar, 
leading to 44.1 tpy SO2 emitted in 2011 from HFB1-1 and 
total facility-wide emissions of 70.8 tpy.\6\
---------------------------------------------------------------------------

    \6\ For more information on this correction to the 2011 NEI, 
Version 2 emissions, see Table 3-8 of the May 12, 2017, submittal.
---------------------------------------------------------------------------

    EPA has evaluated Tennessee's 2011 base year emissions inventory 
for the Sullivan County Area and has made the preliminary determination 
that this inventory was developed consistent with EPA's guidance. 
Therefore, pursuant to section 172(c)(3), EPA is proposing to approve 
Tennessee's 2011 base year emissions inventory for the Sullivan County 
Area.
    The attainment demonstration also provides for a projected 
attainment year inventory that includes estimated emissions for all 
emission sources of SO2 which are determined to impact the 
nonattainment area for the year in which the area is expected to attain 
the standard. This inventory must address any future growth in the 
Area. Growth means any potential increases in emissions of the 
pollutant for which the Sullivan County Area is nonattainment 
(SO2) due to the construction and operation of new major 
sources, major modifications to existing sources, or increased minor 
source activity. TDEC included a statement in its May 12, 2017 
submittal declaring that the air agency assumes no growth of major 
sources in the Sullivan County Area, and that minor source growth 
should not significantly impact the Area. TDEC cites to its ``Growth 
Policy'' found at Tennessee Air Pollution Control Regulations (TAPCR) 
1200-03-09-.01(5), which includes the nonattainment new source review 
(NNSR) program and the requirement for minor sources and minor 
modifications proposing to construct in a nonattainment area to apply 
BACT, approved into the SIP and last updated on July 30, 2012 (see 77 
FR 44481). The NNSR program includes lowest achievable emissions rate, 
offsets, and public hearing requirements for major stationary sources 
and major modifications.
    TDEC provided a future year projected emissions inventory for all 
known sources included in the 2011 base year inventory, discussed 
above, that were determined to impact the Sullivan County Area. The 
projected emissions are set to be accurate beyond October 1, 2018, when 
the control strategy for the attainment demonstration will be fully 
implemented. Therefore, as an annual future year inventory, the point 
source portion is accurate beyond October 1, 2018, and would represent 
an annual inventory for 2019 or beyond. The projected emissions in 
Table 2 are estimated actual emissions, representing a 67.6 percent 
reduction from the base year SO2 emissions. The point source 
emissions were estimated by taking credit for the control strategy to 
repower the boilers at B-253 and assuming actual emissions at other 
Eastman units would remain the same as in 2011. Additionally, 
EnviraGlass has not operated in recent years, and TDEC includes a 
statement in its May 12, 2017 submittal that as of February 2017, the 
source had not resumed its operations. Therefore, EnviraGlass emissions 
were projected as zero tpy. If this source began operation again, 
actual emissions would be much less than those from Eastman (~50 tpy), 
and would be reported in future inventories.
    Per EPA's April 2014 SO2 guidance, the existing 
allowable emissions limits and the new 30-day, combined emission limit 
(see section IV.B.4) that TDEC is requesting EPA approve into the SIP, 
were modeled to show attainment. These projected actual emissions 
included in the future year inventory are less than the allowable 
emission limits, and therefore offer a greater level of certainty that 
the NAAQS will be protected under all operating scenarios. Emissions 
estimates for onroad sources were re-estimated with MOVES2014. The 
nonroad emissions were projected using national growth factors, and 
area source emissions were scaled based on emission factors developed 
using the Annual Energy Outlook 2014 for consumption and production 
forecasts. Both categories were then apportioned to the nonattainment 
area based on

[[Page 30615]]

population in the nonattainment area relative to that of Sullivan 
County.\7\
---------------------------------------------------------------------------

    \7\ For more information, see Attachments A-D of the May 12, 
2017, submittal.

                  Table 2--Projected 2018 SO2 Emissions Inventory for the Sullivan County Area
                                                      [tpy]
----------------------------------------------------------------------------------------------------------------
              Year                     Point          Onroad          Nonroad          Area            Total
----------------------------------------------------------------------------------------------------------------
2011............................        21,956.5            1.62            0.16            10.6       21,968.88
2019............................         7,104.5            0.64           0.006          10.521        7,115.67
----------------------------------------------------------------------------------------------------------------

B. Attainment Modeling Demonstration

    Eastman operates a large manufacturing facility in Kingsport that 
includes major SO2 sources with the potential to emit 
greater than 100 tons per year (tpy) of SO2. The 
SO2 emissions come from three main boiler groups B-83, B-253 
and B-325. Powerhouse B-253 serves five boilers (Boilers 25-29), each 
with an individual stack, that provide steam and electricity to the 
facility. Powerhouse B-325 serves two coal-fired boilers that vent to a 
single stack (Boiler 30 and Boiler 31). Boiler 30 is equipped with a 
spray dryer absorber and electrostatic precipitator to control 
particulate matter and acid gases. Boiler 31 is equipped with a spray 
dryer absorber and fabric filter to control particulate matter and acid 
gases. Powerhouse B-83 serves seven boilers; five coal-fired boilers 
(Boilers 18-22) venting to a single stack, and two coal-fired boilers 
(Boilers 23 and 24) that also burn wastewater treatment sludge, venting 
to a single stack.
    These boilers, along with three other backup natural gas-fired 
boilers with minimal SO2 emissions (B-423), provide process 
steam and most of the electrical power needed to supply Eastman's 
operations. The combination of boilers and boiler operating loads at 
any given time depends on manufacturing demands along with availability 
of boilers, as each boiler has annual scheduled shutdowns. The 
following discussion evaluates various features of the modeling that 
Tennessee used in its attainment demonstration.
1. Model Selection
    Tennessee's attainment demonstration used AERMOD, the preferred 
model for this application, and the associated pre-processor modeling 
programs. The State used the 16216r version of AERMOD with regulatory 
default options and urban dispersion coefficients.\8\ Receptor 
elevations and hill heights required by AERMOD were determined using 
the AERMAP terrain preprocessor version 11103. The meteorological data 
was processed using AERMET version 16216 with the regulatory adjusted 
U* option. The surface characteristics around the meteorological 
surface station were determined using AERSURFACE version 13016 and 
building downwash was assessed with the BPIP processor (version 04274). 
EPA proposes to find these model selections appropriate for the 
attainment demonstration.
---------------------------------------------------------------------------

    \8\ Tennessee and Eastman determined that urban dispersion 
coefficients are appropriate for the modeling analysis based upon an 
assessment of land use within a 3-kilometer radius of the Eastman 
boiler stacks using the Auer technique contained in Section 
7.2.1.1.b.i of 40 CFR part 51, appendix W. The analysis resulted in 
52.4 percent of the area being classified as urban land use 
categories, which is above the 50 percent criteria for using urban 
dispersion coefficients. Additionally, Tennessee and Eastman 
performed an analysis to estimate an effective population for the 
urban option to account for the large industrial heat release at the 
Eastman facility. The results of this analysis yield an effective 
population of 200,000, which is approximately four times the 
approximate 50,000 population of Kingsport, Tennessee. The complete 
details of Tennessee and Eastman's analysis are discussed in Section 
4.1 of Attachment G1, ``NAAQS Attainment Demonstration Modeling 
Analysis,'' in Tennessee's final SIP submittal. EPA preliminarily 
agrees that urban dispersion coefficients with an effective 
population of 200,000 is appropriate for the modeling, and believes 
the procedures to estimate the effective population are appropriate.
---------------------------------------------------------------------------

2. Meteorological Data
    The Sullivan County nonattainment area is in a wide valley 
surrounded by complex terrain ridges. Eastman evaluated available 
surface meteorological data in the area and determined that none of 
nearby National Weather Surface (NWS) stations in area were 
representative of the site-specific winds that occur in the 
nonattainment area valley. Therefore, Eastman installed and operated a 
site-specific 100-meter meteorological data tower and Doppler SODAR 
system to collect profiles of meteorological data (wind speed, wind 
direction, temperature). One year of site-specific data was collected 
from April 1, 2012 through March 31, 2013.\9\ EPA has reviewed the 
site-specific meteorological data and has preliminarily determined that 
the data meets the quality assurance criteria and the 1-year of data is 
appropriate for the modeling analysis. Site-specific turbulence 
parameters (sigma-theta and sigma-w) were also collected. However, as 
recommended in the December 2016 final revisions to the EPA's Guideline 
on Air Quality Models, contained in 40 CFR part 51, appendix W 
(Appendix W), since Eastman chose to use the adjusted U* (surface 
friction velocity) regulatory option in AERMET, the site-specific 
turbulence parameters were not used. The data from the 100-meter tower 
and Doppler SODAR were merged with concurrent additional NWS surface 
data parameters needed by AERMOD (e.g., cloud cover data) from the Tri-
City Regional Airport National Weather Station (13877) and upper air 
data from Nashville, TN (13897).
---------------------------------------------------------------------------

    \9\ Pursuant to Section 8.4.2.e of 40 CFR part 51, appendix W, 
if site-specific meteorology is used for the modeling analysis, at 
least 1-year of site-specific data should be collected. The data 
should meet the quality assurance criteria in EPA's 2000 
``Meteorological Monitoring Guidance for Regulatory Modeling 
Applications.'' Publication No. EPA-454/R-99-005. Office of Air 
Quality Planning and Standards, Research Triangle Park, NC. (NTIS 
No. PB 2001-103606).
---------------------------------------------------------------------------

    The surface roughness (zo), albedo (r), and Bowen ratio (Bo) 
required surface parameters were determined for the area around the 
site-specific meteorological surface station using AERSURFACE version 
13016. Eastman processed the meteorological data and surface parameters 
into AERMOD-ready files using AERMET version 16216 with the regulatory 
adjusted U* option. Complete details of the meteorological data 
collection and processing are available in sections 3.1-3.8 of 
Attachment G1, ``NAAQS Attainment Demonstration Modeling Analysis,'' in 
Tennessee's final SIP submittal. EPA preliminarily finds that the 
meteorological data collection and processing is appropriate for the 
modeled attainment demonstration.
3. Emissions Data
    The emission inputs to Tennessee's attainment demonstration 
modeling reflect 1-hour emissions that correspond to allowable 
emissions from sulfur dioxide emission units at the Eastman facility 
and other nearby emissions sources located within and outside the

[[Page 30616]]

Sullivan County nonattainment area. Eastman's modeled emissions sources 
include nine coal-fired boilers, five natural gas boilers that were 
converted from coal-fired to natural gas-fired units, and a tail-gas 
incineration unit. Although the limit on emissions from Eastman governs 
the 30-day average sum of emissions from all nine coal-fired boilers, 
Tennessee conducted modeling using a constant hourly rate (the 1,905 
lb/hr 1-hour CEV), as recommended by EPA's April 2014 SO2 
guidance. As discussed in more detail in section IV.B.6 below, 
Tennessee has conducted 34 modeling runs using a full range of emission 
distributions, to show that the limit ensures attainment, regardless of 
how emissions are distributed among the various boilers within this 
limit. In addition, Tennessee used the statistical procedures 
recommended in Appendix C of EPA's guidance to establish an adjustment 
factor that it applied to determine the limit it would otherwise have 
set.
    Two additional SO2 emissions sources, EnviraGlass, 
located within the nonattainment area, and Domtar Paper, located just 
outside the nonattainment area, were also included in Tennessee's 
attainment demonstration modeling, modeled at their hourly emission 
limits. Additional details regarding the emissions units are included 
in the Emissions Inventory, section IV.A., of this proposed rule and 
section 2 of Attachment G1, ``NAAQS Attainment Demonstration Modeling 
Analysis,'' in Tennessee's final SIP submittal. EPA proposes to find 
that the emissions sources included in the modeling are appropriate for 
the attainment demonstration. All other sources not explicitly included 
in the modeling were addressed using the background concentration 
discussed in section IV.B.5 of this notice.
4. Emission Limits
    An important prerequisite for approval of an attainment plan is 
that the emission limits that provide for attainment be quantifiable, 
fully enforceable, replicable, and accountable. See General Preamble at 
13567-68. Some of the limits that Tennessee's plan relies on are 
expressed as 30-day average limits. Therefore, part of the review of 
Tennessee's attainment plan must address the use of these limits, both 
with respect to the general suitability of using such limits for this 
purpose and with respect to whether the limits included in the plan 
have been suitably demonstrated to provide for attainment. The first 
subsection that follows addresses the enforceability of the limits in 
the plan, and the second subsection that follows addresses the 
combined, 30-day emission limit for Boilers 18-24, 30 and 31. Sections 
IV.B.6 and 7 discuss the modeling conducted to demonstrate that the 
limit of combined emissions of these boilers suitably provides for 
attainment.
i. Enforceability
    Section 172(c)(6) provides that emission limits and other control 
measures in the attainment SIP shall be enforceable. Tennessee's 
attainment SIP for the Sullivan County nonattainment area relies on 
control measures and enforceable emission limits for Powerhouses B-253, 
B-83 and B-325 (for more discussion on these boilers, please refer to 
section IV.A above). These emission reduction measures were accounted 
for in the attainment modeling for the Eastman facility which 
demonstrates attainment for the 2010 NAAQS.
    Tennessee's control strategy for B-253 relies on compliance with 
the State's Regional Haze SIP to install BART for SO2 and 
other pollutants that impair visibility at Class I areas. TDEC's 
original April 4, 2008, regional haze SIP identified B-253 (Boilers 25-
29) at Eastman Chemical as BART-eligible units.\10\ Tennessee 
subsequently amended its regional haze SIP (May 14, 2012 and May 25, 
2012) to establish BART requirements for Eastman including an 
alternative BART option to repower (convert coal-fired boilers to 
natural gas) Boilers 25-29 at B-253 by December 31, 2018.\11\ The 
alternative BART measure became federally-enforceable through the 
issuance of BART permit 066116H on May 9, 2012, and an amendment on May 
22, 2012, which changed the conversion completion date to align with 
the 1-hour SO2 NAAQS compliance deadline of October 4, 2018 
(Condition 4(f)).\12\ Tennessee issued construction permit 966859F on 
June 15, 2013, authorizing construction of the B-253 boilers conversion 
to natural gas. Condition 6 of Permit 966859F establishes a natural gas 
fuel restriction after conversion is complete for each boiler.
---------------------------------------------------------------------------

    \10\ A BART-eligible source is an emission source that has the 
potential to emit 250 tons or more of a visibility-impairing 
pollutant, was constructed between August 7, 1962 and August 7, 
1977, and whose operations fall within one or more of 26 listed 
source categories. The Clean Air Act requires BART for any BART-
eligible source that a State determines ``emits any air pollutant 
which may reasonably be anticipated to cause or contribute to any 
impairment of visibility in any such area.'' EPA finalized a limited 
approval/limited disapproval of portions of Tennessee's April 4, 
2008, regional haze SIP on April 24, 2012 (77 FR 24392). The April 
4, 2008, SIP established the State's plan to comply with federal 
requirements to ensure natural visibility conditions at Class I 
areas by requiring affected sources to install BART for 
SO2 and other visibility-impairing pollutants.
    \11\ Tennessee's initial Eastman BART determination required 
Eastman to reduce SO2 emissions at Boilers 25-29 either 
by 92 percent or comply with a limit of 0.20 lbs/MMBtu established 
through the BART permit (066116H). EPA approved Eastman's BART 
determination, the alternative BART option and permit 066116H on 
November 27, 2012 (77 FR 70689).
    \12\ Condition 4(f) also prohibits operation of any B-253 boiler 
not converted after the October 2018 SO2 NAAQS compliance 
date until repowered to natural gas.
---------------------------------------------------------------------------

    In conjunction with the natural gas conversion control strategy at 
B-253, Tennessee also established a 30-day combined SO2 
emission limit for nine coal-fired boilers at B-83 (seven boilers) and 
B-325 (two boilers) pursuant to EPA's April 2014 SO2 
guidance on longer term average limits (see section IV.B.4.ii below). 
Tennessee established a single, combined 30-day rolling average of 
1,753 lbs/hr SO2 emission limit through Permit 070072F on 
May 10, 2017, for Boilers 18-24 at B-83 and Boilers 30-31 at B-325. 
Boilers 30 and 31 at B-325 also have existing individual SO2 
emission limits of 317 lbs/hr and 293 lbs/hr, respectively, based on a 
30-calendar day rolling average.\13\ Eastman must comply with the 
combined 30-day limit for the 30-day period ending on October 31, 2018 
\14\ and each 30-day period thereafter. Therefore, Eastman must begin 
to comply with the new limit no later than October 2, 2018. Compliance 
will be determined based on continuous emission monitoring system 
(CEMS) data for all nine boilers. EPA provides additional details, 
section IV.B.4.ii below, regarding how the combined 30-day 
SO2 emission limit was derived. The enforceable emission 
limit and compliance parameter ensure control measures will achieve the 
necessary incremental SO2 emissions reductions necessary to 
attain the NAAQS as expeditiously as practicable. Based on

[[Page 30617]]

the attainment modeling of B-253 repowering combined with the 30-day 
SO2 emission limits for B-83 and B-325, the area is 
projected to begin showing attaining monitoring design values.
---------------------------------------------------------------------------

    \13\ Established in construction Permit 955272F, Boiler 30 has a 
317 lbs/hr 30-day SO2 limit and Boiler 31 has a 293 lbs/
hr 30-day SO2 limit, giving B-325 an allowable limit of 
610 lbs/hr on a 30-day average.
    \14\ EPA's April 2014 SO2 guidance recommends that 
attainment plans provide for compliance at least one calendar year 
prior to the attainment deadline, to facilitate collection of air 
quality monitoring data reflecting attainment plan implementation. 
This air quality data would indicate whether the attainment plan is 
in fact successfully providing for attainment. Nevertheless, the 
guidance also notes that EPA has the discretion to approve plans 
that are judged to provide for attainment by the statutory 
attainment deadline, even if the monitoring data collected prior to 
the attainment deadline are judged to indicate that that plan has 
not yielded timely attainment. EPA believes that Tennessee's 
attainment plan provides for attainment, notwithstanding the 
possibility that subsequent review of available monitoring data may 
support a conclusion that the plan did not in fact provide for 
timely attainment.
---------------------------------------------------------------------------

    Tennessee's May 11, 2017, attainment SIP requests EPA approve into 
the SIP the authorization for alternative BART repowering of Boilers 
25-29 at B-253 at Condition 4(f) of Regional Haze permit 066116H \15\ 
(approved into Tennessee's regional haze SIP on November 12, 2012), 
natural gas fuel restriction for Boilers 25-29 (after each natural gas 
conversion) at Condition 6 of PSD construction permit 966859F, and the 
30-day rolling single, combined SO2 emission limit of 1,753 
lbs/hr for boilers at B-83 and B-325 at Conditions 1 through 4 \16\ of 
permit 070072F, which also include compliance parameters (monitoring, 
recordkeeping and reporting). The accountability of the SO2 
emission limit is established through TDEC's inclusion in the 
nonattainment SIP and in the attainment modeling demonstration to 
ensure permanent and enforceable emission limitations as necessary to 
provide for attainment of the 2010 SO2 NAAQS.
---------------------------------------------------------------------------

    \15\ EPA notes condition 4(f) was approved into Tennessee's SIP 
on November 12, 2012 as part of the State's Regional Haze SIP. See77 
FR 70689.
    \16\ In Tennessee's SO2 attainment SIP (page 33) the 
state requested EPA approve Conditions 1-5 from Permit 070072F 
however, EPA notes only four conditions were included in the final 
issued permit.
---------------------------------------------------------------------------

ii. Longer Term Average Limits
    Tennessee has developed a single, combined emission limit of 1,753 
lbs/hr of SO2 emissions on a 30-day average basis. This 
emission limit applies to nine coal-fired boilers, which emit 
SO2 from three separate stacks from powerhouses B-83 and B-
325. These nine coal-fired boilers help provide both steam and 
electricity for the Eastman facility and Boilers 23 and 24 (at B-83) 
also burn wastewater treatment sludge. Based on the unique, 
interconnected operations and the steam demand for the Eastman 
facility, Tennessee elected to establish a single, combined emission 
limit governing the sum of emissions from these nine boilers. Tennessee 
concluded that the NAAQS will be attained so long as total hourly 
emissions from these nine boilers are at or below 1,905 lbs/hr. 
Tennessee based this conclusion on a set of 34 modeling runs, which 
encompassed several ``worst-case'' emissions scenarios. These scenarios 
and the modeling results are described in detail in section IV.B.6 of 
this notice. EPA ordinarily uses the term critical emissions value 
(CEV) to mean the 1-hour emission rate for an individual stack that, in 
combination with the other CEVs for other relevant stacks, the state 
shows through proper modeling to yield attainment. However, in this 
case, EPA is using the term CEV to mean the total emissions from all 
nine Eastman coal-fired boilers emitting from three stacks that 
Tennessee has shown to yield attainment, reflecting Tennessee's 
approach of evaluating an appropriate limit on the sum of these 
emissions.
    After establishment of this combined-source CEV, Tennessee used the 
procedures recommended in Appendix C of EPA's April 2014 SO2 
guidance to determine an adjustment factor with which to establish a 
single, combined emission limit with a longer term averaging time (30-
day). Tennessee analyzed three years of historical hourly emissions 
data (2013-2015) from the nine boilers in question. Tennessee used the 
sum of emissions from the nine boilers in this analysis, determining a 
99th percentile of the 1-hour total emissions values and a 99th 
percentile of the 30-day average total emission values. The ratio of 
these 99th percentile values yielded an adjustment factor of 0.92. 
Multiplication of this adjustment factor times the collective CEV 
yielded a 30-day average limit of 1,753 lbs/hr. EPA believes that 
Tennessee, by following the approach recommended in Appendix C of the 
April 2014 SO2 guidance, has justified a conclusion that 
this 1,753 lbs/hour limit (governing the sum of emissions from the nine 
boilers) may be considered comparably stringent to a 1-hour limit of 
1,905 lbs/hr (again governing the sum of emissions from the nine 
boilers). Since the emission limit being established for these nine 
boilers is a single, combined limit, EPA believes it is appropriate for 
the adjustment factor also to be computed based on the total combined 
emissions from the nine boilers. Therefore, EPA proposes to agree that 
the adjustment factor of 0.92 is appropriate in this case.
    EPA's April 2014 SO2 guidance further states, ``The 
second important factor in assessing whether a longer term average 
limit provides appropriate protection against NAAQS violations is 
whether the source can be expected to comply with a longer term average 
limit in a manner that minimizes the frequency of occasions with 
elevated emissions and magnitude of emissions on those occasions.'' The 
guidance advises that the establishment of supplemental limits to 
provide direct constraints on the frequency and/or magnitude of 
emissions exceeding the CEV can be valuable, but the guidance also 
acknowledges the possibility that occasions of emissions exceeding the 
CEV may be rare and modest in magnitude even without supplemental 
enforceable limitations. Tennessee concluded that occasions of 
emissions exceeding the critical emissions would be infrequent and 
modest in magnitude even without adoption of supplemental limits. EPA 
conducted its own evaluation of whether this element of the guidance is 
satisfied, such that compliance with Tennessee's 30-day average 
emission limit would provide adequate confidence that the area will 
attain the standard.
    The historical emissions data do not provide a direct measure of 
the frequency and magnitude of elevated emissions to expect once 
Eastman complies with the 30-day limit. The historical Eastman 
emissions data that Tennessee used is from a period in which emissions 
frequently were higher than the new limit. During the 2013 to 2015 
period, Eastman's total emissions exceeded the subsequently adopted 
limit (1,753 lbs/hr) in approximately 32.4 percent of 30-day averages, 
and exceeded the 1-hour CEV (1,905 lbs/hr) in approximately 21.5 
percent of hours. Thus, Eastman will be required to make emission 
reductions sufficient to comply with the new 30-day limit (1,753 lb/
hr), which would both eliminate the occasions of 30-day average 
emissions above 1,753 lbs/hr and reduce the number and possibly 
eliminate the occasions when 1-hour emission levels exceed 1,905 lbs/
hr. The question then is how frequently and with what associated 
emission levels can 1-hour emissions levels be expected to exceed the 
CEV once Eastman complies with the 30-day average limit.
    Since Tennessee has permitted a combined, multi-stack emission 
limit (1,753 lb/hr) for the nine coal-fired boilers, there are multiple 
compliance scenarios possible. Consequently, there is also a range of 
frequencies that the hourly emissions can exceed the CEV while still 
meeting the 30-day permit limit. To forecast the frequency and 
magnitude of emissions of occasions with emissions above the CEV, EPA 
asked Tennessee for information regarding how Eastman expects to comply 
with the new limit. Tennessee responded \17\ that Eastman's compliance 
strategy will likely be to modify the order of dispatch of the nine 
boilers in question, dispatching Boilers 18 through 22 from Powerhouse 
B-83 less often in the future, in particular by reducing the 
dispatching of the smaller coal-fired boilers (Boilers 18, 19, and 20) 
in favor

[[Page 30618]]

of greater operation of the larger boilers that are being converted to 
burn natural gas.\18\ These smaller boilers are the oldest and least 
efficient boilers of the nine and provide only low pressure steam to 
the facility. EPA used this information provided by Tennessee and the 
less efficient nature of these boilers and further analyzed the 
historical (2013 to 2015) emissions. Given the order of preference in 
boiler dispatch provided by Tennessee and efficiency considerations, 
EPA expects that three boilers (B-18 to B-20) may be operated at 
approximately 20 percent of their historical rates. This level of 
operation for these boilers would yield compliance with the new limit 
and allow Eastman to meet its steam generation needs. With that level 
of operation of those boilers, the number of occasions of total plant 
emissions exceeding the CEV was found to be 1.1 percent of the hours, 
with these hours on average being 4.4 percent above the CEV.\19\ During 
EPA's analyses, we found that the frequency of emissions over the CEV 
could range from 1 to 10 percent of the time, depending on the 
operational scenario used to comply with the 30-day limit. While EPA 
acknowledges the uncertainty in forecasting the frequency of elevated 
emissions and the magnitude of emissions on those occasions, based on 
the information received from Tennessee and our own analysis, EPA 
believes that emissions at Eastman are unlikely to exceed the CEV more 
than a few percent of the hours, at levels generally only a modest 
percent over the CEV. Compliance with the 30-day limit will be ensured 
using a CEMS and appropriate monitoring, recordkeeping and reporting 
requirements. Consequently, EPA proposes to conclude that the second 
criterion for use of longer term average limits is satisfied, even 
without supplemental limits to constrain the frequency and emissions 
level of occasions when emissions exceed the CEV.
---------------------------------------------------------------------------

    \17\ See emails from TDEC to EPA Region 4 dated January 26 and 
February 8, 2018.
    \18\ Tennessee's analysis in the February 8 email confirmed 
that, under the new combined limit, there should be adequate 
capacity available at natural gas boilers at B-253 and B-423, 
without the need to revise existing permit limits for these 
individual units.
    \19\ The email correspondence with TDEC and supporting 
documentation (including Tennessee's spreadsheet data and EPA's 
spreadsheet used for these calculations) are in the docket (ID: EPA-
R04-OAR-2017-0626) for this proposed rule.
---------------------------------------------------------------------------

    Based on a review of the State's submittal, EPA believes that the 
single, combined 30-day average limit for the nine boilers in 
Powerhouses B-83 and B-325, in conjunction with the existing individual 
30-day average limits for Boilers B-30 and B-31, provides a suitable 
alternative to establishing a 1-hour average emission limit for each 
unit or for the collected units at this source. Further discussion of 
Tennessee's modeling analysis of its set of limits, along with 
discussion of pertinent considerations in applying the procedures of 
Appendix C of EPA's guidance in determining appropriate longer term 
limits, is provided in section IV.B.6 below. In summary, EPA believes 
that the State has used a suitable data base in an appropriate manner 
and has thereby applied an appropriate adjustment, yielding an emission 
limit that has comparable stringency to the 1-hour average limit that 
the State determined would otherwise have been necessary to provide for 
attainment. While the 30-day average limit allows for occasions in 
which emissions may be higher than the level that would be allowed with 
the combined-unit 1-hour limit, the State's limit compensates by 
requiring average emissions to be lower than the level that would 
otherwise have been required by a 1-hour average limit. As described 
above in this section, in section III and explained in more detail in 
EPA's April 2014 SO2 guidance for nonattainment plans, EPA 
believes that appropriately set longer term average limits provide a 
reasonable basis by which nonattainment plans may provide for 
attainment. Based on the general information provided in this guidance 
document as well as the information in Tennessee's attainment SIP, EPA 
proposes to find that the 30-day average limit for Eastman's nine 
boilers in combination with other limitations in the State's plan will 
provide for attainment of the NAAQS.
5. Background Concentration
    In accordance with section 8.3 of 40 CFR part 51, appendix W, 
Tennessee's attainment demonstration addresses the impacts from all 
SO2 emissions sources not explicitly included in the AERMOD 
modeling analysis by adding representative background concentrations to 
the impacts from the modeled sources. The State and Eastman chose to 
use 2013-2015 ambient monitoring data from a sulfur dioxide monitor 
located at Mammoth Cave National Park in Kentucky (AQS ID 21-061-0501) 
to develop ``seasonal by hour of the day'' background concentrations. 
The hourly concentrations range from 2.79 to 18.51 micrograms per cubic 
meter ([micro]g/m\3\). The complete details of the background 
concentrations are described in section 3.9 of Attachment G1 of the 
Tennessee's Attainment Demonstration submittal. EPA preliminarily finds 
use of the Mammoth Cave background data is appropriate for the 
attainment modeling analysis.
6. Analysis of Multi-Stack Limit
    The use of a limit governing the sum of emissions from multiple 
stacks, in lieu of individual limits for each stack, calls for a 
demonstration that the worst-case distribution of these emissions 
provides for attainment. To provide this demonstration, Tennessee 
conducted thirty-four (34) AERMOD modeling runs using varying 
combinations of boiler load and emissions scenarios for the nine coal-
fired boilers to verify that the modeling includes the worst-case 
operational scenarios allowed under the single, thirty-day rolling 
average, emissions limit of 1,753 lbs/hr for the nine coal-fired 
boilers. The 34 modeling scenarios were performed to derive the single, 
combined 1,905 lbs/hr CEV for the nine coal-fired boilers (two stacks 
at the B-83 Powerhouse and one stack at the B-325 Powerhouse) that 
results in modeled attainment of the NAAQS. As defined in EPA's April 
2014 SO2 guidance, the CEV is the level of emissions that 
results in modeled concentrations that are just below the level of the 
NAAQS; as noted above, this term is being applied to the combination of 
emissions from the nine coal-fired boilers referenced earlier in the 
notice.
    With these 34 AERMOD modeling runs, Tennessee and Eastman evaluated 
a wide range of future potential operational scenarios, considering 
boiler steam load demands for Eastman's production processes and boiler 
load-shifting that is projected to occur once the conversion of the 
five coal-fired boilers at B-253 (Boilers 25-29) from burning coal to 
natural gas is completed by October 2018. Based upon this evaluation, 
34 operational scenarios were selected by Tennessee and Eastman for the 
CEV modeling analysis. Four of these 34 operation scenarios reflected 
all of the SO2 being emitted from a single stack, including 
two scenarios where all of the 1,905 lbs/hr is released from one or the 
other of the two B-83 stacks individually, one scenario where the B-325 
stack emitted 726 lbs/hr \20\ (which is the one hour equivalent to the 
current permitted, federally enforceable allowable

[[Page 30619]]

emissions limit for B-325), and one scenario where the B-325 stack 
emitted 1,800 lbs/hr to simulate a B-325 worst-case emissions scenario. 
The modeled predicted concentrations from the three single-stack 
scenarios with permissible emission levels ranged from 89.08 [micro]g/
m\3\ to 182.7 [micro]g/m\3\; the scenario with B-325 emitting 1,800 
lbs/hr, well above its permissible level, yielded an estimated highest 
concentration of 190.8 [micro]g/m\3\. Nine modeling scenarios were 
performed to evaluate emissions from various combinations when two of 
the three stacks are in operation. For these scenarios, the 1,905 lbs/
hr CEV rate was divided between the two stacks in multiple combinations 
to represent reasonable potential worst-case future operations. The 
modeled predicted concentrations from the nine two-stack scenarios 
range from 171.6 [micro]g/m\3\ to 190.5 [micro]g/m\3\, with the highest 
value of 190.5 [micro]g/m\3\ resulting from a scenario when the Boilers 
18-22 B-83 stack was emitting at the highest level near its maximum 
capacity (1,039 lbs/hr), the Boilers 23-24 B-83 stack was emitting near 
its average rate (866 lbs/hr), and Boilers 30-31 were not operating (0 
lb/hr). Twenty-one modeling scenarios were performed to evaluate 
simultaneous operation of all three stacks. As with the two-stack 
scenarios, the 1,905 lbs/hr critical value emissions rate was divided 
among the three stacks in multiple combinations to represent reasonable 
potential worst-case future operations. The modeled predicted 
concentrations from the twenty-one three-stack scenarios range from 
186.0 [micro]g/m\3\ to 195.37 [micro]g/m\3\. The maximum model 
predicted concentration from the three-stack scenarios, which is also 
the maximum for all 34 scenarios, 195.37 [micro]g/m\3\, occurred in the 
three-stack operational scenario that assumes the majority of the 
emissions came from the Boilers 18-22 B-83 stack emitting near its 
maximum capacity (1,133 lbs/hr), emissions were slightly below normal 
from the Boilers 23-24 B-83 stack (719 lbs/hr), and emissions were low 
from the B-325 stack (53 lbs/hr, as Boiler 30 was assumed to not be 
operating and Boiler 31 operating under minimal load). Tables which 
summarize the emissions and modeling input parameters for each of the 
34 scenarios and additional details about the full range of scenarios 
are contained in the State's modeling analysis in sections 7.11 and 
7.12 of the State's Attainment Demonstration Submittal and section 5 of 
Attachment G1, ``NAAQS Attainment Demonstration Modeling Analysis,'' in 
Tennessee's final SIP submittal.
---------------------------------------------------------------------------

    \20\ Established in PSD Permit 955272F, Boiler 30 has a 317 lbs/
hr 30-day SO2 limit and Boiler 31 has a 293 lbs/hr 30-day 
SO2 limit, giving B-325 an allowable limit of 610 lbs/hr 
on a 30-day average. For the purposes of modeling, Eastman 
calculated an adjustment factor specific to the B-325 stack in 
accordance with the methods of Appendix C of EPA's guidance. Eastman 
calculated an adjustment factor of 0.84, which yielded a 
corresponding one-hour emission rate of 726 lbs/hr.
---------------------------------------------------------------------------

    As noted earlier, in calculating the adjustment factor to multiply 
times the collective CEV (the 1-hour sum of emissions providing for 
attainment in the full range of distribution of the emissions) to 
determine a comparably stringent collective 30-day emission limit, 
Tennessee used statistics for the sum of emissions from all the stacks 
governed by this limit. EPA's guidance does not expressly recommend how 
to address comparable stringency for limits that address the sum of 
emissions across multiple stacks. However, EPA's guidance at page 32 
states:

    The selection of data handling procedures influences the longer 
term averages that are computed and thus influences the relationship 
between a 1-hour limit and a comparably stringent longer term 
average limit. Therefore, . . . all analyses for determining 
comparably stringent longer term average limits should then apply 
those data handling procedures.

This suggests that the computation of adjustment factors for a limit 
governing the sum of emissions from multiple stacks should be based on 
statistical analysis of the variability of the sum of emissions from 
the multiple stacks, irrespective of the variability of emissions from 
the individual stacks. In the case of Eastman, while the facility 
shifts load among its various boilers, resulting in relatively variable 
emissions at any boiler, the total load is relatively steady, resulting 
in only modest variability of total emissions. As a result, use of a 
30-day limit makes less difference in the control measure needed to 
meet the limit, and so less adjustment is needed to establish a 30-day 
limit that is comparably stringent to the corresponding 1-hour limit. 
Given the demonstration that the full range of potential distributions 
of 1,905 lb/hr provides for attainment, EPA also believes that a 30-day 
average limit of 1,753 lb/hr provides suitable assurance that 
attainment would result under the full range of distribution of these 
allowable emissions.
7. Summary of Modeling Results
    The AERMOD modeling analysis contained in Tennessee's Attainment 
Demonstration submittal resulted in a maximum modeled design value of 
195.37 [micro]g/m\3\, including the background concentration, which is 
less than the 196.4 [micro]g/m\3\ (75 ppb) 1-hour sulfur dioxide NAAQS.
    EPA has evaluated the modeling procedures, inputs and results and 
proposes to find that the results of the State's modeling analysis 
demonstrate that there are no modeled violations of the NAAQS within 
the nonattainment area when the combined emissions from the nine coal-
fired boilers are no greater that the 1,905 lbs/hr CEV. Additionally, 
EPA proposes to find that the 34 modeling scenarios are adequate to 
address the range of possible future operating scenarios of the boilers 
at the Eastman facility and, therefore, support that the 1,905 lbs/hr 
combined CEV is appropriate. Section IV.B.4.ii. of this notice explains 
how Tennessee and Eastman developed the 1,753 lbs/hr 30-day rolling 
average permit limit following the procedures in EPA's April 2014 
SO2 guidance.

C. RACM/RACT

    CAA section 172(c)(1) requires that each attainment plan provide 
for the implementation of all RACM as expeditiously as practicable 
(including such reductions in emissions from existing sources in the 
area as may be obtained through the adoption, at a minimum, of RACT) 
and shall provide for attainment of the NAAQS. EPA interprets RACM, 
including RACT, under section 172, as measures that a state determines 
to be reasonably available and which contribute to attainment as 
expeditiously as practicable for existing sources in the area.
    Tennessee's plan for attaining the 1-hour SO2 NAAQS in 
the Sullivan County SO2 nonattainment area is based on 
several measures, including repowering the B-253 boilers from coal to 
natural gas operation. Tennessee's plan requires compliance with these 
measures by October 1, 2018. This date is consistent with Tennessee's 
Regional Haze SIP, which was amended on May 9, 2012. The amended SIP 
allowed Eastman to implement BART no later than April 30, 2017, or an 
alternative BART option (repowering of the boilers from coal to natural 
gas) by December 31, 2018. The alternative BART option became federally 
enforceable with the issuance of BART permit 066116H on May 9, 2012. A 
prevention of significant deterioration (PSD) construction permit 
(966859F), which authorizes construction for the boiler repowering, was 
issued June 5, 2013. Condition 4(f) of permit 066116H requires the 
repowering of B-253 to be completed no later than the compliance 
deadline for the one-hour SO2 NAAQS. Also, Tennessee 
evaluated B-325 Boiler 31, and determined that the spray dryer 
absorber/fabric filter baghouse combination already in place 
constitutes RACT, and that therefore no further analysis is required.
    Tennessee considered various other measures for the remaining B-83 
and B-325 boilers. The State evaluated a range of measures to reduce 
SO2 emissions,

[[Page 30620]]

including switching to low-sulfur coal, upgraded or additional control 
equipment, conversion of existing coal-fired boilers to natural gas, 
and replacing existing coal-fired boilers with natural gas boilers. 
Tennessee determined that these other measures are not reasonable for a 
variety reasons, including infeasibility and cost, and that they were 
not needed to attain the NAAQS and would not advance the attainment 
date. See Table 5-2 in the submittal for additional details on the 
measures analyzed. In addition, Tennessee evaluated other operations at 
Eastman as well as additional sources within and adjacent to the 
nonattainment area and determined that no additional controls were 
required as RACT.
    Tennessee has determined that repowering B-253 to natural gas 
constitutes RACT and EPA proposes to concur with the state's RACT 
analysis. Based on the attainment modeling, described herein, for the 
B-253 control measures combined with the 30-day SO2 emission 
limit for B-83 and B-325, the area is projected to show attainment of 
the 1-hour SO2 standard. EPA believes the attainment plan 
provides for attainment through the adoption and implementation of 
Tennessee's RACT/RACM emission control strategy. Therefore, EPA 
proposes to conclude that the state has satisfied the requirement in 
section 172(c)(1) to adopt and submit all RACM as needed to attain the 
standards as expeditiously as practicable.

D. New Source Review (NSR)

    Tennessee's SIP-approved NSR rules for nonattainment areas (NNSR) 
are at TAPCR 1200-03-09-.01(5), last approved by EPA on July 30, 2012. 
See 77 FR 44481. These rules provide for appropriate NSR for 
SO2 sources undergoing construction or major modification in 
the Sullivan County Area without need for modification of the approved 
rules. Therefore, EPA proposes to conclude that this requirement is met 
for this Area through Tennessee's existing NSR rules.

E. Reasonable Further Progress (RFP)

    The CAA section 172(c)(2) requires the SIP provide reasonable 
further progress towards attainment of the applicable NAAQS. Regarding 
part D nonattainment plans, section 171(1) of the CAA defines RFP as 
the annual incremental reduction in emissions of the relevant pollutant 
as are required for the purpose of ensuring attainment of the 
applicable NAAQS by the applicable date. As discussed above, 
Tennessee's 2008 regional haze SIP required Eastman implement BART at 
B-253 (Boilers 25-29). The State revised its SIP to establish an 
alternative BART option to repower/convert all five coal-fired boilers 
at B-253 to natural gas units and changed the compliance deadline to 
the 1-hour SO2 NAAQS attainment date or October 4, 2018.\21\ 
TDEC and Eastman indicated that the size and complexity of the 
repowering required additional time to ensure the conversion was 
technically feasible. Tennessee's control strategy to reduce 
SO2 emission and attain the 2010 standard as expeditiously 
as practicable include the repowering of the five coal-fired boilers at 
B-253 and imposing an SO2 emission limit for the nine coal-
fired boilers for B-83 and B-325. Eastman established a repowering 
timeline for B-253 listed in Table 3 below and in Tennessee' 
SO2 attainment SIP.
---------------------------------------------------------------------------

    \21\ Tennessee's attainment SIP mistakenly states that the 1-
hour SO2 attainment date is October 5, 2018 instead of 
October 4, 2018.

       Table 3--Estimated Compliance Schedule for B-253 Repowering
------------------------------------------------------------------------
           Boiler                Date \22\              Activity
------------------------------------------------------------------------
25..........................  1st              Complete; startup date
                               Quarter(Q1),     was April 23, 2014.
                               2014.
27..........................  1st and 2nd      Equipment mobilization,
                               Quarter in       six-week conversion and
                               2016.            demobilization; pre-
                                                outage construction
                                                conducted 4th quarter of
                                                2017 thru the 1st
                                                quarter in 2018.
                                               Conversion Complete--
                                                start-up date was April
                                                23, 2016.
28..........................  2nd and 3rd      Equipment mobilization,
                               Quarter in       six-week conversion and
                               2016.            demobilization; pre-
                                                outage construction
                                                conducted 4th quarter of
                                                2017 thru the 1st
                                                quarter in 2018.
                                               Conversion Complete--
                                                start-up date was
                                                October 2, 2016.
29..........................  1st and 2nd      Equipment mobilization,
                               Quarter in       six-week conversion and
                               2018.            demobilization; pre-
                                                outage construction
                                                conducted 4th quarter of
                                                2017 thru the 1st
                                                quarter in 2018.
                                               Conversion Complete--
                                                start-up date was March
                                                30, 2018.
26..........................  3rd Quarter in   Equipment mobilization,
                               2018.            six-week conversion and
                                                demobilization; pre-
                                                outage construction
                                                conducted 4th quarter of
                                                2017 thru the 1st
                                                quarter in 2018.
------------------------------------------------------------------------

    Based on this projected timeline, Eastman intends to complete 
conversion of B-253 by the 3rd quarter of 2018 just before the October 
4, 2018 attainment date. At the time of this proposed rulemaking, four 
of the five coal-fired boilers at B-253 (B-25, 27, 28, and 29) have 
been converted, are fully operational and currently subject to the 
natural gas fuel restriction established in Permit 966859F. According 
to Eastman, this compliance schedule was the most practicable to meet 
the BART requirements and attain the SO2 NAAQS to maintain 
the necessary steam and electricity for manufacturing operations. This 
is also due, in part, to the state required (Tennessee Code Section 68-
122-110) annual boiler safety inspection and maintenance of all 17 
boilers at Eastman (including B-253) while ensuring necessary boiler 
capacity to sustain facility operations.\23\ According to Eastman, to 
complete the conversion of a boiler to natural gas the normal safety 
inspection is extended to 6 weeks. Because of extended inspections and 
boiler shutdowns in 2017, Eastman did not convert any boilers at B-253 
in 2017. As indicated in Table 3, the final boiler (B-26) is scheduled 
for conversion in the 3rd quarter of 2018.
---------------------------------------------------------------------------

    \22\ According to TDEC, Eastman did not schedule the conversion 
of any boilers in 2015 or 2017 due to legally required annual boiler 
safety inspections and maintenance to ensure facility steam and 
electricity reliability. The necessary engineering work for the 
conversion of Boilers 27 and 28 in 2016 was performed in 2015 and 
2017 for Boilers 26 and 29. For additional information, please refer 
to Tennessee's Attainment SIP Narrative located in the docket (ID: 
EPA-R04-OAR-2017-0626).
    \23\ The Tennessee Boiler and Unfired Pressure Vessel inspection 
law (Tennessee Code Section 68-122-110) requires annual inspection 
and maintenance of Eastman's 17 power boilers. According to Eastman, 
only one boiler at a time is taken off-line to ensure the necessary 
steam and electricity reliability for manufacturing operations. The 
duration of each inspection depends on the size and maintenance 
cycle of the boiler components. Eastman has stated it takes 46-48 of 
the 52 weeks to complete the scheduled inspections and boiler 
maintenance. Eastman also indicated that it is not practicable for 
the facility to schedule more than two extended inspections per 
calendar year without potential risk meeting production demands.

---------------------------------------------------------------------------

[[Page 30621]]

    Tennessee's May 2017 attainment SIP also provides estimated 
incremental emission reductions during the conversion of all five 
boilers at B-253. Table 6-2 in TDEC's submittal \24\ provides for 
projected change in actual emissions at Eastman over the duration of 
the repowering at B-253 and post-control after the attainment date. 
TDEC compared the pre-control emission rates for all boilers at B-83, 
B-325 and B-253 for the period of April 1, 2012 through March 31, 2013 
over the course of the conversion (interim years 2015 and 2017) to 
post-control emissions (after October 4, 2018). Projected emission 
reductions after the completion of B-253 conversion and compliance with 
the SO2 emission limit for B-83 and B-325, are expected to 
be 66 percent compared to pre-control levels (with estimated 
incremental emission reductions of 11 percent and 39 percent in 2015 
and 2017 respectively (after complete conversion of B-25 in 2014 and B-
27 and 28 in 2016). The average pre-control emissions from each B-253 
boiler was 677 pounds per hour (or 2,965 tpy). TDEC estimates that each 
boiler conversion will reduce emissions by 2,960 tpy.
---------------------------------------------------------------------------

    \24\ EPA notes the second note to Table 6-2 list 1,794 lbs/hr as 
the combined 30-day average allowable emission rate for B-83 and B-
325 boilers, however, the correct emission rate is 1,753 lbs/hr.
---------------------------------------------------------------------------

    The control measures for attainment of the 2010 SO2 
NAAQS included in the State's submittal have been modeled to achieve 
attainment of the 1-hour SO2 NAAQS. The adoption of new 
emissions limits, and compliance parameters and a natural gas 
restriction (for repowered B-253 boilers) require these control 
measures to achieve emissions reductions. Tennessee finds that the 
attainment plan requires the affected sources to implement control 
measures as expeditiously as practicable to ensure attainment of the 1-
hour standard and therefore concludes that the attainment plan provides 
for RFP in accordance with the approach to RFP described in EPA's 
guidance. EPA believes Tennessee's SIP provides for incremental 
reduction in emissions to ensure reasonable further progress towards 
attainment of the standard and therefore concurs and proposes to 
preliminary conclude that the plan provides for RFP and therefore 
satisfies the requirements of CAA section 172(c)(2).

F. Contingency Measures

    As noted above, EPA guidance describes special features of 
SO2 planning that influence the suitability of alternative 
means of addressing the requirement in section 172(c)(9) for 
contingency measures for SO2, such that in particular an 
appropriate means of satisfying this requirement is for the state to 
have a comprehensive enforcement program that identifies sources of 
violations of the SO2 NAAQS and to undertake an aggressive 
follow-up for compliance and enforcement. Tennessee's plan provides for 
satisfying the contingency measure requirement in this manner.
    Specifically, upon notification by Tennessee that a reference 
monitor for the Area has registered four validated ambient 
SO2 concentrations in excess of the NAAQS during calendar 
years 2019 or 2020, or that a monitored SO2 NAAQS violation 
based on the design value occurred during calendar years 2021 and 
beyond, Eastman will, without any further action by Tennessee or EPA, 
undertake a full system audit of all emission units subject to emission 
limits under this plan and submit a written system audit report to 
Tennessee within 30 days of the notification. Upon receipt of the 
system audit report, Tennessee will immediately begin a 30-day 
evaluation period to diagnose the cause of the monitored exceedance. 
This evaluation will be followed by a 30-day consultation period with 
Eastman to develop and implement operational changes necessary to 
prevent future monitored violations of the NAAQS. These changes may 
include fuel switching to reduce or eliminate the use of sulfur-
containing fuels, physical or operational reduction of production 
capacity, or other changes as appropriate. If a permit modification is 
deemed necessary, Tennessee would issue a final permit within the 
statutory timeframes required in Tennessee Comprehensive Rules and 
Regulations 1200-03-09, and any new emissions limits required by such a 
permit would be submitted to EPA as a SIP revision. EPA concurs and 
proposes to approve Tennessee's plan for meeting the contingency 
measure requirement in this manner.

V. Additional Elements of Tennessee's Submittal

    To verify that the 30-day limit is resulting in continued 
attainment of the 1-hour SO2 standard in the Sullivan County 
area, Tennessee is establishing an additional safeguard within the 
nonattainment area by upgrading its existing SO2 ambient air 
monitoring network in the Sullivan County area. TDEC has committed to 
deploy additional ambient air monitors within the nonattainment area 
\25\ to characterize expected areas of maximum 1-hour SO2 
concentrations near the Eastman Chemical Plant. The State intends to 
designate the monitors as State/Local air monitoring stations in 
accordance with 40 CFR part 58 and locate the monitors as close as 
possible to the areas of expected maximum concentration. These monitors 
will be submitted for approval by EPA as part of the state's annual 
ambient air monitoring network plan.
---------------------------------------------------------------------------

    \25\ See email from TDEC to EPA Region 4, Air, Pesticides and 
Toxic Management Division, Air Director Beverly Banister on June 6, 
2018 included in the docket for this proposal (ID: EPA-R04-OAR-2017-
0626).
---------------------------------------------------------------------------

VI. Incorporation by Reference

    EPA is proposing to include in a final EPA rule regulatory text 
that includes incorporation by reference. In accordance with 
requirements of 1 CFR 51.5, EPA is proposing to incorporate by 
reference into Tennessee's SIP a natural gas fuel restriction, a new 
SO2 emission limit and specified compliance conditions 
established in permits 966859F and 070072F for monitoring, 
recordkeeping and reporting parameters for emissions units at Eastman 
Chemical Company. Specifically, EPA is proposing to incorporate into 
the Tennessee SIP, a new 1,753 lbs/hr 30-day SO2 emission 
limit and operating, monitoring, recordkeeping and reporting parameters 
all established at Conditions 1 thru 4 in Permit 070072F for Boilers 
18-24 at B-83 and Boilers 30-31 at B-325 and, a natural gas fuel 
restriction for Boilers 25-29 at B-253 (after each natural gas 
conversion) established at Condition 6 in Permit 966859F. The 
SO2 emission standards specified in each permit are the 
basis for the SO2 attainment demonstration in the SIP. EPA 
has made, and will continue to make, these materials generally 
available through www.regulations.gov and at EPA Region 4 office 
(please contact the person identified in the For FURTHER INFORMATION 
CONTACT section of this preamble for more information).

VII. EPA's Proposed Action

    EPA is proposing to approve Tennessee's SO2 
nonattainment SIP submission, which the State submitted to EPA on May 
11, 2017, for attaining the 2010 1-hour SO2 NAAQS for the 
Sullivan County Area and for meeting other nonattainment area planning 
requirements. EPA has preliminarily determined that Tennessee's 
nonattainment SIP meets the applicable requirements of sections 110(a), 
172, 191 and 192 of the CAA and regulatory requirements at 40 CFR part 
51. This

[[Page 30622]]

SO2 nonattainment SIP includes Tennessee's attainment 
demonstration for the Sullivan County Area and other nonattainment 
requirements for a RFP, RACT/RACM, NNSR, base-year and projection-year 
emission inventories, enforceable emission limits and compliance 
parameters and contingency measures. Specifically, EPA is proposing to 
approve into the Tennessee SIP, Eastman Chemical's enforceable 
SO2 emission limit and compliance parameters (monitoring, 
recordkeeping and reporting) from PSD construction permit 966859F 
(condition 6) and Permit No. 070072F (conditions 1-4) (see section 
IV.B.4.1).

VIII. 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);
     Is not an Executive Order 13771 (82 FR 9339, February 2, 
2017) regulatory action because SIP approvals are exempted under 
Executive Order 12866;
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (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, Reporting and recordkeeping 
requirements, Sulfur oxides.

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

    Dated: June 19, 2018.
Onis ``Trey'' Glenn, III,
Regional Administrator, Region 4.
[FR Doc. 2018-14097 Filed 6-28-18; 8:45 am]
 BILLING CODE 6560-50-P


