Approval and Promulgation of Air Quality Implementation Plans; State of Tennessee; Regional Haze State Implementation Plan, 33662-33685 [2011-14292]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 76, Number 111 (Thursday, June 9, 2011)]
[Proposed Rules]
[Pages 33662-33685]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-14292]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R04-OAR-2009-0786-201033; FRL-9317-6]


Approval and Promulgation of Air Quality Implementation Plans; 
State of Tennessee; Regional Haze State Implementation Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA is proposing a limited approval and a limited disapproval 
of a revision to the Tennessee State Implementation Plan (SIP) 
submitted by the State of Tennessee through the Tennessee Department of 
Environment and Conservation (TDEC) on April 4, 2008, that addresses 
regional haze for the first implementation period. This revision 
addresses the requirements of the Clean Air Act (CAA) and EPA's rules 
that require states to prevent any future and remedy any existing 
anthropogenic impairment of visibility in mandatory Class I areas 
caused by emissions of air pollutants from numerous sources located 
over a wide geographic area (also referred to as the ``regional haze 
program''). States are required to assure reasonable progress toward 
the national goal of achieving natural visibility conditions in Class I 
areas. EPA is proposing a limited approval of this SIP revision to 
implement the regional haze requirements for Tennessee on the basis 
that the revision, as a whole, strengthens the Tennessee SIP. Also in 
this action, EPA is proposing a limited disapproval of this same SIP 
revision because of the deficiencies in the State's April 2008 regional 
haze SIP submittal arising from the remand by the U.S. Court of Appeals 
for the District of Columbia (DC Circuit) to EPA of the Clean Air 
Interstate Rule (CAIR).

DATES: Comments must be received on or before July 11, 2011.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R04-
OAR-2009-0786, by one of the following methods:
    1. https://www.regulations.gov: Follow the on-line instructions for 
submitting comments.
    2. E-mail: spann.jane@epa.gov.
    3. Fax: 404-562-9029.
    4. Mail: EPA-R04-OAR-2009-0786, Regulatory Development Section, Air 
Planning Branch, Air, Pesticides and Toxics Management Division, U.S. 
Environmental Protection Agency, Region 4, 61 Forsyth Street, SW., 
Atlanta, Georgia 30303-8960.
    5. Hand Delivery or Courier: Jane Spann, Acting Chief, Regulatory 
Development Section, Air Planning Branch, Air, Pesticides and Toxics 
Management Division, U.S. Environmental Protection Agency, Region 4, 61 
Forsyth Street, SW., Atlanta, Georgia 30303-8960. Such deliveries are 
only accepted during the Regional Office's normal hours of operation. 
The Regional Office's official hours of business are Monday through 
Friday, 8:30 to 4:30, excluding Federal holidays.
    Instructions: Direct your comments to Docket ID No. ``EPA-R04-OAR-
2009-0786.'' EPA's policy is that all comments received will be 
included in the public docket without change and may be made available 
online at: https://www.regulations.gov, including any personal 
information provided, unless the comment includes information claimed 
to be Confidential Business Information (CBI) or other information 
whose disclosure is restricted by statute. Do not submit through https://www.regulations.gov or e-mail, information that you consider to be CBI 
or otherwise protected. The https://www.regulations.gov Web site is an 
``anonymous access'' system, which means EPA will not know your 
identity or contact information unless you provide it in the body of 
your comment. If you send an e-mail comment directly to EPA without 
going through https://www.regulations.gov, your e-mail address will be 
automatically captured and included as part of the comment that is 
placed in the public docket and made available on the Internet. If you 
submit an electronic comment, EPA recommends that you include your name 
and other contact information in the body of your comment and with any 
disk or CD-ROM you submit. If EPA cannot read your comment due to 
technical difficulties and cannot contact you for clarification, EPA 
may not be able to consider your comment. Electronic files should avoid 
the use of special characters, any form of encryption, and be free of 
any defects or viruses. For additional information about EPA's public 
docket visit the EPA Docket Center homepage at https://www.epa.gov/epahome/dockets.htm.
    Docket: All documents in the electronic docket are listed in the 
https://www.regulations.gov index. Although listed in the index, some 
information is not publicly available, i.e., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, is not placed on the Internet and will be 
publicly available only in hard copy form. Publicly available docket 
materials are available either electronically in https://www.regulations.gov or in hard copy at the Regulatory Development 
Section, Air Planning Branch, Air, Pesticides and Toxics Management 
Division, U.S. Environmental Protection Agency, Region 4, 61 Forsyth 
Street, SW., Atlanta, Georgia 30303-8960. EPA requests that if at all 
possible, you contact the person listed in the FOR FURTHER INFORMATION 
CONTACT section to schedule your inspection. The Regional Office's 
official hours of business are Monday through Friday, 8:30 to 4:30, 
excluding Federal holidays.

FOR FURTHER INFORMATION CONTACT: Sara Waterson or Michele Notarianni, 
Regulatory Development Section, Air Planning Branch, Air, Pesticides 
and Toxics Management Division, U.S. Environmental Protection Agency,

[[Page 33663]]

Region 4, 61 Forsyth Street, SW, Atlanta, Georgia 30303-8960. Sara 
Waterson can be reached at telephone number (404) 562-9061 and by 
electronic mail at waterson.sara@epa.gov. Michele Notarianni can be 
reached at telephone number (404) 562-9031 and by electronic mail at 
notarianni.michele@epa.gov.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. What action is EPA proposing to take?
II. What is the background for EPA's proposed action?
    A. The Regional Haze Problem
    B. Requirements of the CAA and EPA's Regional Haze Rule (RHR)
    C. Roles of Agencies in Addressing Regional Haze
III. What are the requirements for the regional haze SIPs?
    A. The CAA and the RHR
    B. Determination of Baseline, Natural, and Current Visibility 
Conditions
    C. Determination of Reasonable Progress Goals (RPGs)
    D. Best Available Retrofit Technology (BART)
    E. Long-Term Strategy (LTS)
    F. Coordinating Regional Haze and Reasonably Attributable 
Visibility Impairment (RAVI) LTS
    G. Monitoring Strategy and Other Implementation Plan 
Requirements
    H. Consultation With States and Federal Land Managers (FLMs)
IV. What is the relationship of the CAIR to the regional haze 
requirements?
    A. Overview of EPA's CAIR
    B. Remand of the CAIR
    C. Regional Haze SIP Elements Potentially Affected by the CAIR 
Remand
    D. Rationale and Scope of Proposed Limited Approval
V. What is EPA's analysis of Tennessee's regional haze submittal?
    A. Affected Class I Areas
    B. Determination of Baseline, Natural and Current Visibility 
Conditions
    1. Estimating Natural Visibility Conditions
    2. Estimating Baseline Conditions
    3. Summary of Baseline and Natural Conditions
    4. Uniform Rate of Progress
    C. Long-Term Strategy/Strategies
    1. Emissions Inventory for 2018 With Federal and State Control 
Requirements
    2. Modeling To Support the LTS and Determine Visibility 
Improvement for Uniform Rate of Progress
    3. Relative Contributions to Visibility Impairment: Pollutants, 
Source Categories, and Geographic Areas
    4. Procedure for Identifying Sources To Evaluate for Reasonable 
Progress Controls in Tennessee and Surrounding Areas
    5. Application of the Four CAA Factors in the Reasonable 
Progress Analysis
    6. BART
    7. RPGs
    D. Coordination of RAVI and Regional Haze Requirements
    E. Monitoring Strategy and Other Implementation Plan 
Requirements
    F. Consultation With States and FLMs
    1. Consultation With Other States
    2. Consultation With the FLMs
    G. Periodic SIP Revisions and Five-Year Progress Reports
VI. What action is EPA proposing?
VII. Statutory and Executive Order Reviews

I. What action is EPA proposing to take?

    EPA is proposing a limited approval of Tennessee's April 4, 2008, 
SIP revision addressing regional haze under CAA sections 301(a) and 
110(k)(3) because the revision as a whole strengthens the Tennessee 
SIP. However, the Tennessee SIP relies on CAIR, an EPA rule, to satisfy 
key elements of the regional haze requirements. Due to the remand of 
CAIR, see North Carolina v. EPA, 531 F.3d 836 (DC Cir. 2008), the 
revision does not meet all of the applicable requirements of the CAA 
and EPA's regulations as set forth in sections 169A and 169B of the CAA 
and in 40 CFR 51.300-308. As a result, EPA is concurrently proposing a 
limited disapproval of Tennessee's SIP revision. The revision 
nevertheless represents an improvement over the current SIP, and makes 
considerable progress in fulfilling the applicable CAA regional haze 
program requirements. This proposed rulemaking and the accompanying 
Technical Support Document \1\ (TSD) explain the basis for EPA's 
proposed limited approval and limited disapproval actions.
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    \1\ EPA's TSD to this action, entitled, ``Technical Support 
Document for Tennessee Regional Haze Submittal,'' is included in the 
public docket for this action.
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    Under CAA sections 301(a) and 110(k)(6) and EPA's long-standing 
guidance, a limited approval results in approval of the entire SIP 
submittal, even of those parts that are deficient and prevent EPA from 
granting a full approval of the SIP revision. Processing of State 
Implementation Plan (SIP) Revisions, EPA Memorandum from John Calcagni, 
Director, Air Quality Management Division, OAQPS, to Air Division 
Directors, EPA Regional Offices I-X, September 7, 1992, (1992 Calcagni 
Memorandum) located at https://www.epa.gov/ttn/caaa/t1/memoranda/siproc.pdf. The deficiencies that EPA has identified as preventing a 
full approval of this SIP revision relate to the status and impact of 
CAIR on certain interrelated and required elements of the regional haze 
program. At the time the Tennessee regional haze SIP was being 
developed, the State's reliance on CAIR was fully consistent with EPA's 
regulations, see 70 FR 39104, 39142-4143 (July 6, 2005). CAIR, as 
originally promulgated, requires significant reductions in emissions of 
sulfur dioxide (SO2) and nitrogen oxides (NOX) to 
limit the interstate transport of these pollutants, and the reliance on 
CAIR by affected states as an alternative to requiring BART for 
electrical generating units (EGUs) had specifically been upheld in 
Utility Air Regulatory Group v. EPA, 471 F.3d 1333 (DC Cir. 2006). In 
2008, however, the DC Circuit remanded CAIR back to EPA. See North 
Carolina v. EPA, 550 F.3d 1176. The Court found CAIR to be inconsistent 
with the requirements of the CAA, see North Carolina v. EPA, 531 F.3d 
896 (DC Cir. 2008), but ultimately remanded the rule to EPA without 
vacatur because it found that ``allowing CAIR to remain in effect until 
it is replaced by a rule consistent with [the court's] opinion would at 
least temporarily preserve the environmental values covered by CAIR.'' 
North Carolina v. EPA, 550 F.3d at 1178. In response to the court's 
decision, EPA has proposed a new rule to address interstate transport 
of NOX and SO2 in the eastern United States. See 
75 FR 45210 (Aug. 2, 2010) (``the Transport Rule''). EPA explained in 
that proposal that the Transport Rule, when finalized, will replace 
CAIR and the CAIR Federal implementation plans (FIPs). In other words, 
the CAIR and CAIR FIP requirements, which were found to be illegal by 
the DC Circuit, will not remain in force after the Transport Rule 
requirements are in place. Given the status of CAIR, EPA is proposing 
to find that Tennessee may not rely on CAIR in its present form to 
provide reductions to satisfy the reasonable progress and BART 
requirements of the regional haze program.
    While CAIR will not remain in effect indefinitely, it is currently 
in force. See North Carolina v. EPA, 550 F.3d 1176. By granting limited 
approval of Tennessee's regional haze SIP, EPA will allow the State to 
rely on the emissions reductions associated with CAIR for so long as 
CAIR is in place. EPA believes that this course of action is consistent 
with the court's intention to keep CAIR in place in order to 
``temporarily preserve the environmental values covered by CAIR.'' Id, 
at 1178.

II. What is the background for EPA's proposed action?

A. The regional haze problem

    Regional haze is visibility impairment that is produced by a 
multitude of sources and activities which are located across a broad 
geographic area and emit

[[Page 33664]]

fine particles (PM2.5) (e.g., sulfates, nitrates, organic 
carbon, elemental carbon, and soil dust), and their precursors (e.g., 
SO2, NOX, and in some cases, ammonia 
(NH3) and volatile organic compounds (VOC)). Fine particle 
precursors react in the atmosphere to form fine particulate matter 
which impairs visibility by scattering and absorbing light. Visibility 
impairment reduces the clarity, color, and visible distance that one 
can see. PM2.5 can also cause serious health effects and 
mortality in humans and contributes to environmental effects such as 
acid deposition and eutrophication.
    Data from the existing visibility monitoring network, the 
``Interagency Monitoring of Protected Visual Environments'' (IMPROVE) 
monitoring network, show that visibility impairment caused by air 
pollution occurs virtually all the time at most national park and 
wilderness areas. The average visual range \2\ in many Class I areas 
(i.e., national parks and memorial parks, wilderness areas, and 
international parks meeting certain size criteria) in the western 
United States is 100-150 kilometers, or about one-half to two-thirds of 
the visual range that would exist without anthropogenic air pollution. 
In most of the eastern Class I areas of the United States, the average 
visual range is less than 30 kilometers, or about one-fifth of the 
visual range that would exist under estimated natural conditions. See 
64 FR 35715 (July 1, 1999).
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    \2\ Visual range is the greatest distance, in kilometers or 
miles, at which a dark object can be viewed against the sky.
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B. Requirements of the CAA and EPA's Regional Haze Rule (RHR)

    In section 169A of the 1977 Amendments to the CAA, Congress created 
a program for protecting visibility in the nation's national parks and 
wilderness areas. This section of the CAA establishes as a national 
goal the ``prevention of any future, and the remedying of any existing, 
impairment of visibility in mandatory Class I Federal areas \3\ which 
impairment results from manmade air pollution.'' On December 2, 1980, 
EPA promulgated regulations to address visibility impairment in Class I 
areas that is ``reasonably attributable'' to a single source or small 
group of sources, i.e., ``reasonably attributable visibility 
impairment''. See 45 FR 80084. These regulations represented the first 
phase in addressing visibility impairment. EPA deferred action on 
regional haze that emanates from a variety of sources until monitoring, 
modeling and scientific knowledge about the relationships between 
pollutants and visibility impairment were improved.
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    \3\ Areas designated as mandatory Class I Federal areas consist 
of national parks exceeding 6,000 acres, wilderness areas and 
national memorial parks exceeding 5,000 acres, and all international 
parks that were in existence on August 7, 1977. See 42 U.S.C. 
7472(a). In accordance with section 169A of the CAA, EPA, in 
consultation with the Department of Interior, promulgated a list of 
156 areas where visibility is identified as an important value. See 
44 FR 69122 (November 30, 1979). The extent of a mandatory Class I 
area includes subsequent changes in boundaries, such as park 
expansions. See 42 U.S.C. 7472(a). Although states and Tribes may 
designate as Class I additional areas which they consider to have 
visibility as an important value, the requirements of the visibility 
program set forth in section 169A of the CAA apply only to 
``mandatory Class I Federal areas.'' Each mandatory Class I Federal 
area is the responsibility of a ``Federal Land Manager.'' See 42 
U.S.C. 7602(i). When we use the term ``Class I area'' in this 
action, we mean a ``mandatory Class I Federal area.''
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    Congress added section 169B to the CAA in 1990 to address regional 
haze issues. EPA promulgated a rule to address regional haze on July 1, 
1999 (64 FR 35713), the RHR. The RHR revised the existing visibility 
regulations to integrate into the regulation provisions addressing 
regional haze impairment and established a comprehensive visibility 
protection program for Class I areas. The requirements for regional 
haze, found at 40 CFR 51.308 and 51.309, are included in EPA's 
visibility protection regulations at 40 CFR 51.300-309. Some of the 
main elements of the regional haze requirements are summarized in 
section III of this preamble. The requirement to submit a regional haze 
SIP applies to all 50 states, the District of Columbia and the Virgin 
Islands.\4\ 40 CFR 51.308(b) requires states to submit the first 
implementation plan addressing regional haze visibility impairment no 
later than December 17, 2007.
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    \4\ Albuquerque/Bernalillo County in New Mexico must also submit 
a regional haze SIP to completely satisfy the requirements of 
section 110(a)(2)(D) of the CAA for the entire State of New Mexico 
under the New Mexico Air Quality Control Act (section 74-2-4).
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C. Roles of Agencies in Addressing Regional Haze

    Successful implementation of the regional haze program will require 
long-term regional coordination among states, tribal governments and 
various Federal agencies. As noted above, pollution affecting the air 
quality in Class I areas can be transported over long distances, even 
hundreds of kilometers. Therefore, to effectively address the problem 
of visibility impairment in Class I areas, states need to develop 
strategies in coordination with one another, taking into account the 
effect of emissions from one jurisdiction on the air quality in 
another.
    Because the pollutants that lead to regional haze can originate 
from sources located across broad geographic areas, EPA has encouraged 
the states and Tribes across the United States to address visibility 
impairment from a regional perspective. Five regional planning 
organizations (RPOs) were developed to address regional haze and 
related issues. The RPOs first evaluated technical information to 
better understand how their states and Tribes impact Class I areas 
across the country, and then pursued the development of regional 
strategies to reduce emissions of particulate matter (PM) and other 
pollutants leading to regional haze.
    The Visibility Improvement State and Tribal Association of the 
Southeast (VISTAS) RPO is a collaborative effort of state governments, 
tribal governments, and various Federal agencies established to 
initiate and coordinate activities associated with the management of 
regional haze, visibility and other air quality issues in the 
Southeastern United States. Member state and tribal governments 
include: Alabama, Florida, Georgia, Kentucky, Mississippi, North 
Carolina, South Carolina, Tennessee, Virginia, West Virginia, and the 
Eastern Band of the Cherokee Indians.

III. What are the requirements for regional haze SIPs?

A. The CAA and the RHR

    Regional haze SIPs must assure reasonable progress towards the 
national goal of achieving natural visibility conditions in Class I 
areas. Section 169A of the CAA and EPA's implementing regulations 
require states to establish long-term strategies for making reasonable 
progress toward meeting this goal. Implementation plans must also give 
specific attention to certain stationary sources that were in existence 
on August 7, 1977, but were not in operation before August 7, 1962, and 
require these sources, where appropriate, to install BART controls for 
the purpose of eliminating or reducing visibility impairment. The 
specific regional haze SIP requirements are discussed in further detail 
below.

B. Determination of Baseline, Natural, and Current Visibility 
Conditions

    The RHR establishes the deciview as the principal metric or unit 
for expressing visibility. This visibility metric expresses uniform 
changes in haziness in terms of common

[[Page 33665]]

increments across the entire range of visibility conditions, from 
pristine to extremely hazy conditions. Visibility expressed in 
deciviews is determined by using air quality measurements to estimate 
light extinction and then transforming the value of light extinction 
using a logarithm function. The deciview is a more useful measure for 
tracking progress in improving visibility than light extinction itself 
because each deciview change is an equal incremental change in 
visibility perceived by the human eye. Most people can detect a change 
in visibility at one deciview.\5\
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    \5\ The preamble to the RHR provides additional details about 
the deciview. See 64 FR 35714, 35725 (July 1, 1999).
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    The deciview is used in expressing RPGs (which are interim 
visibility goals towards meeting the national visibility goal), 
defining baseline, current, and natural conditions, and tracking 
changes in visibility. The regional haze SIPs must contain measures 
that ensure ``reasonable progress'' toward the national goal of 
preventing and remedying visibility impairment in Class I areas caused 
by anthropogenic air pollution by reducing anthropogenic emissions that 
cause regional haze. The national goal is a return to natural 
conditions, i.e., anthropogenic sources of air pollution would no 
longer impair visibility in Class I areas.
    To track changes in visibility over time at each of the 156 Class I 
areas covered by the visibility program (40 CFR 81.401-437), and as 
part of the process for determining reasonable progress, states must 
calculate the degree of existing visibility impairment at each Class I 
area at the time of each regional haze SIP submittal and periodically 
review progress every five years midway through each 10-year 
implementation period. To do this, the RHR requires states to determine 
the degree of impairment (in deciviews) for the average of the 20 
percent least impaired (``best'') and 20 percent most impaired 
(``worst'') visibility days over a specified time period at each of 
their Class I areas. In addition, states must also develop an estimate 
of natural visibility conditions for the purpose of comparing progress 
toward the national goal. Natural visibility is determined by 
estimating the natural concentrations of pollutants that cause 
visibility impairment and then calculating total light extinction based 
on those estimates. EPA has provided guidance to states regarding how 
to calculate baseline, natural and current visibility conditions in 
documents titled, EPA's Guidance for Estimating Natural Visibility 
Conditions Under the Regional Haze Rule, September 2003, (EPA-454/B-03-
005 located at https://www.epa.gov/ttncaaa1/t1/memoranda/rh_envcurhr_gd.pdf), (hereinafter referred to as ``EPA's 2003 Natural Visibility 
Guidance''), and Guidance for Tracking Progress Under the Regional Haze 
Rule, September 2003, (EPA-454/B-03-004 located at https://www.epa.gov/ttncaaa1/t1/memoranda/rh_tpurhr_gd.pdf)), (hereinafter referred to as 
``EPA's 2003 Tracking Progress Guidance'').
    For the first regional haze SIPs that were due by December 17, 
2007, ``baseline visibility conditions'' were the starting points for 
assessing ``current'' visibility impairment. Baseline visibility 
conditions represent the degree of visibility impairment for the 20 
percent least impaired days and 20 percent most impaired days for each 
calendar year from 2000 to 2004. Using monitoring data for 2000 through 
2004, states are required to calculate the average degree of visibility 
impairment for each Class I area, based on the average of annual values 
over the five-year period. The comparison of initial baseline 
visibility conditions to natural visibility conditions indicates the 
amount of improvement necessary to attain natural visibility, while the 
future comparison of baseline conditions to the then current conditions 
will indicate the amount of progress made. In general, the 2000-2004 
baseline period is considered the time from which improvement in 
visibility is measured.

C. Determination of Reasonable Progress Goals (RPGs)

    The vehicle for ensuring continuing progress towards achieving the 
natural visibility goal is the submission of a series of regional haze 
SIPs from the states that establish two RPGs (i.e., two distinct goals, 
one for the ``best'' and one for the ``worst'' days) for every Class I 
area for each (approximately) 10-year implementation period. The RHR 
does not mandate specific milestones or rates of progress, but instead 
calls for states to establish goals that provide for ``reasonable 
progress'' toward achieving natural (i.e., ``background'') visibility 
conditions. In setting RPGs, states must provide for an improvement in 
visibility for the most impaired days over the (approximately) 10-year 
period of the SIP, and ensure no degradation in visibility for the 
least impaired days over the same period.
    States have significant discretion in establishing RPGs, but are 
required to consider the following factors established in section 169A 
of the CAA and in EPA's RHR at 40 CFR 51.308(d)(1)(i)(A): (1) The costs 
of compliance; (2) the time necessary for compliance; (3) the energy 
and non-air quality environmental impacts of compliance; and (4) the 
remaining useful life of any potentially affected sources. States must 
demonstrate in their SIPs how these factors are considered when 
selecting the RPGs for the best and worst days for each applicable 
Class I area. States have considerable flexibility in how they take 
these factors into consideration, as noted in EPA's Guidance for 
Setting Reasonable Progress Goals under the Regional Haze Program, 
(``EPA's Reasonable Progress Guidance''), July 1, 2007, memorandum from 
William L. Wehrum, Acting Assistant Administrator for Air and 
Radiation, to EPA Regional Administrators, EPA Regions 1-10 (pp.4-2, 5-
1). In setting the RPGs, states must also consider the rate of progress 
needed to reach natural visibility conditions by 2064 (referred to as 
the ``uniform rate of progress'' or the ``glidepath'') and the emission 
reduction measures needed to achieve that rate of progress over the 10-
year period of the SIP. Uniform progress towards achievement of natural 
conditions by the year 2064 represents a rate of progress which states 
are to use for analytical comparison to the amount of progress they 
expect to achieve. In setting RPGs, each state with one or more Class I 
areas (``Class I state'') must also consult with potentially 
``contributing states,'' i.e., other nearby states with emission 
sources that may be affecting visibility impairment at the Class I 
state's areas. See 40 CFR 51.308(d)(1)(iv).

D. Best Available Retrofit Technology (BART)

    Section 169A of the CAA directs states to evaluate the use of 
retrofit controls at certain larger, often uncontrolled, older 
stationary sources in order to address visibility impacts from these 
sources. Specifically, section 169A(b)(2)(A) of the CAA requires states 
to revise their SIPs to contain such measures as may be necessary to 
make reasonable progress towards the natural visibility goal, including 
a requirement that certain categories of existing major stationary 
sources \6\ built between 1962 and 1977 procure, install, and operate 
the ``Best Available Retrofit Technology'' as determined by the state. 
Under the RHR, states are directed to conduct BART determinations for 
such ``BART-eligible'' sources that may be anticipated to cause or 
contribute to any visibility

[[Page 33666]]

impairment in a Class I area. Rather than requiring source-specific 
BART controls, states also have the flexibility to adopt an emissions 
trading program or other alternative program as long as the alternative 
provides greater reasonable progress towards improving visibility than 
BART.
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    \6\ The set of ``major stationary sources'' potentially subject 
to BART is listed in CAA section 169A(g)(7).
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    On July 6, 2005, EPA published the Guidelines for BART 
Determinations Under the Regional Haze Rule at Appendix Y to 40 CFR 
Part 51 (hereinafter referred to as the ``BART Guidelines'') to assist 
states in determining which of their sources should be subject to the 
BART requirements and in determining appropriate emission limits for 
each applicable source. In making a BART determination for a fossil 
fuel-fired electric generating plant with a total generating capacity 
in excess of 750 megawatts, a state must use the approach set forth in 
the BART Guidelines. A state is encouraged, but not required, to follow 
the BART Guidelines in making BART determinations for other types of 
sources.
    States must address all visibility-impairing pollutants emitted by 
a source in the BART determination process. The most significant 
visibility impairing pollutants are SO2, NOX, and 
PM. EPA has stated that states should use their best judgment in 
determining whether VOC or NH3 compounds impair visibility 
in Class I areas.
    Under the BART Guidelines, states may select an exemption threshold 
value for their BART modeling, below which a BART-eligible source would 
not be expected to cause or contribute to visibility impairment in any 
Class I area. The state must document this exemption threshold value in 
the SIP and must state the basis for its selection of that value. Any 
source with emissions that model above the threshold value would be 
subject to a BART determination review. The BART Guidelines acknowledge 
varying circumstances affecting different Class I areas. States should 
consider the number of emission sources affecting the Class I areas at 
issue and the magnitude of the individual sources' impacts. Any 
exemption threshold set by the state should not be higher than 0.5 
deciview.
    In their SIPs, states must identify potential BART sources, 
described as ``BART-eligible sources'' in the RHR, and document their 
BART control determination analyses. In making BART determinations, 
section 169A(g)(2) of the CAA requires that states consider the 
following factors: (1) The costs of compliance, (2) the energy and non-
air quality environmental impacts of compliance, (3) any existing 
pollution control technology in use at the source, (4) the remaining 
useful life of the source, and (5) the degree of improvement in 
visibility which may reasonably be anticipated to result from the use 
of such technology. States are free to determine the weight and 
significance to be assigned to each factor.
    A regional haze SIP must include source-specific BART emission 
limits and compliance schedules for each source subject to BART. Once a 
state has made its BART determination, the BART controls must be 
installed and in operation as expeditiously as practicable, but no 
later than five years after the date of EPA approval of the regional 
haze SIP. See CAA section 169(g)(4)); see 40 CFR 51.308(e)(1)(iv). In 
addition to what is required by the RHR, general SIP requirements 
mandate that the SIP must also include all regulatory requirements 
related to monitoring, recordkeeping, and reporting for the BART 
controls on the source.
    As noted above, the RHR allows states to implement an alternative 
program in lieu of BART so long as the alternative program can be 
demonstrated to achieve greater reasonable progress toward the national 
visibility goal than would BART. Under regulations issued in 2005 
revising the regional haze program, EPA made just such a demonstration 
for CAIR. See 70 FR 39104 (July 6, 2005). EPA's regulations provide 
that states participating in the CAIR cap-and trade program under 40 
CFR part 96 pursuant to an EPA-approved CAIR SIP or which remain 
subject to the CAIR FIP in 40 CFR part 97 need not require affected 
BART-eligible EGUs to install, operate, and maintain BART for emissions 
of SO2 and NOX. See 40 CFR 51.308(e)(4). Since 
CAIR is not applicable to emissions of PM, states were still required 
to conduct a BART analysis for PM emissions from EGUs subject to BART 
for that pollutant.

E. Long-Term Strategy (LTS)

    Consistent with the requirement in section 169A(b) of the CAA that 
states include in their regional haze SIP a 10 to 15 year strategy for 
making reasonable progress, section 51.308(d)(3) of the RHR requires 
that states include a LTS in their regional haze SIPs. The LTS is the 
compilation of all control measures a state will use during the 
implementation period of the specific SIP submittal to meet applicable 
RPGs. The LTS must include ``enforceable emissions limitations, 
compliance schedules, and other measures as necessary to achieve the 
reasonable progress goals'' for all Class I areas within, or affected 
by emissions from, the state. See 40 CFR 51.308(d)(3).
    When a state's emissions are reasonably anticipated to cause or 
contribute to visibility impairment in a Class I area located in 
another state, the RHR requires the impacted state to coordinate with 
the contributing states in order to develop coordinated emissions 
management strategies. See 40 CFR 51.308(d)(3)(i). In such cases, the 
contributing state must demonstrate that it has included, in its SIP, 
all measures necessary to obtain its share of the emission reductions 
needed to meet the RPGs for the Class I area. The RPOs have provided 
forums for significant interstate consultation, but additional 
consultations between states may be required to sufficiently address 
interstate visibility issues. This is especially true where two states 
belong to different RPOs.
    States should consider all types of anthropogenic sources of 
visibility impairment in developing their LTS, including stationary, 
minor, mobile, and area sources. At a minimum, states must describe how 
each of the following seven factors listed below are taken into account 
in developing their LTS: (1) Emission reductions due to ongoing air 
pollution control programs, including measures to address RAVI; (2) 
measures to mitigate the impacts of construction activities; (3) 
emissions limitations and schedules for compliance to achieve the RPG; 
(4) source retirement and replacement schedules; (5) smoke management 
techniques for agricultural and forestry management purposes including 
plans as currently exist within the state for these purposes; (6) 
enforceability of emissions limitations and control measures; and (7) 
the anticipated net effect on visibility due to projected changes in 
point, area, and mobile source emissions over the period addressed by 
the LTS. See 40 CFR 51.308(d)(3)(v).

 F. Coordinating Regional Haze and Reasonably Attributable Visibility 
Impairment (RAVI) LTS

    As part of the RHR, EPA revised 40 CFR 51.306(c) regarding the LTS 
for RAVI to require that the RAVI plan must provide for a periodic 
review and SIP revision not less frequently than every three years 
until the date of submission of the state's first plan addressing 
regional haze visibility impairment, which was due December 17, 2007, 
in accordance with 40 CFR 51.308(b) and (c). On or before this date, 
the state must revise its plan to provide for review and revision of a 
coordinated LTS for

[[Page 33667]]

addressing RAVI and regional haze, and the state must submit the first 
such coordinated LTS with its first regional haze SIP. Future 
coordinated LTS's, and periodic progress reports evaluating progress 
towards RPGs, must be submitted consistent with the schedule for SIP 
submission and periodic progress reports set forth in 40 CFR 51.308(f) 
and 51.308(g), respectively. The periodic review of a state's LTS must 
report on both regional haze and RAVI impairment and must be submitted 
to EPA as a SIP revision.

G. Monitoring Strategy and Other Implementation Plan Requirements

    Section 51.308(d)(4) of the RHR includes the requirement for a 
monitoring strategy for measuring, characterizing, and reporting of 
regional haze visibility impairment that is representative of all 
mandatory Class I Federal areas within the state. The strategy must be 
coordinated with the monitoring strategy required in section 51.305 for 
RAVI. Compliance with this requirement may be met through 
``participation'' in the IMPROVE network, i.e., review and use of 
monitoring data from the network. The monitoring strategy is due with 
the first regional haze SIP, and it must be reviewed every five years. 
The monitoring strategy must also provide for additional monitoring 
sites if the IMPROVE network is not sufficient to determine whether 
RPGs will be met.
    The SIP must also provide for the following:
     Procedures for using monitoring data and other information 
in a state with mandatory Class I areas to determine the contribution 
of emissions from within the state to regional haze visibility 
impairment at Class I areas both within and outside the state;
     Procedures for using monitoring data and other information 
in a state with no mandatory Class I areas to determine the 
contribution of emissions from within the state to regional haze 
visibility impairment at Class I areas in other states;
     Reporting of all visibility monitoring data to the 
Administrator at least annually for each Class I area in the state, and 
where possible, in electronic format;
     Developing a statewide inventory of emissions of 
pollutants that are reasonably anticipated to cause or contribute to 
visibility impairment in any Class I area. The inventory must include 
emissions for a baseline year, emissions for the most recent year for 
which data are available, and estimates of future projected emissions. 
A state must also make a commitment to update the inventory 
periodically; and
     Other elements, including reporting, recordkeeping, and 
other measures necessary to assess and report on visibility.
    The RHR requires control strategies to cover an initial 
implementation period extending to the year 2018, with a comprehensive 
reassessment and revision of those strategies, as appropriate, every 10 
years thereafter. Periodic SIP revisions must meet the core 
requirements of section 51.308(d) with the exception of BART. The 
requirement to evaluate sources for BART applies only to the first 
regional haze SIP. Facilities subject to BART must continue to comply 
with the BART provisions of section 51.308(e), as noted above. Periodic 
SIP revisions will assure that the statutory requirement of reasonable 
progress will continue to be met.

H. Consultation With States and Federal Land Managers (FLMs)

    The RHR requires that states consult with FLMs before adopting and 
submitting their SIPs. See 40 CFR 51.308(i). States must provide FLMs 
an opportunity for consultation, in person and at least 60 days prior 
to holding any public hearing on the SIP. This consultation must 
include the opportunity for the FLMs to discuss their assessment of 
impairment of visibility in any Class I area and to offer 
recommendations on the development of the RPGs and on the development 
and implementation of strategies to address visibility impairment. 
Further, a state must include in its SIP a description of how it 
addressed any comments provided by the FLMs. Finally, a SIP must 
provide procedures for continuing consultation between the state and 
FLMs regarding the state's visibility protection program, including 
development and review of SIP revisions, five-year progress reports, 
and the implementation of other programs having the potential to 
contribute to impairment of visibility in Class I areas.

IV. What is the relationship of the CAIR to the regional haze 
requirements?

A. Overview of EPA's CAIR

    CAIR, as originally promulgated, requires 28 states and the 
District of Columbia to reduce emissions of SO2 and 
NOX that significantly contribute to, or interfere with 
maintenance of, the national ambient air quality standards (NAAQS) for 
fine particulates and/or ozone in any downwind state. See 70 FR 25162 
(May 12, 2005). CAIR establishes emission budgets or caps for 
SO2 and NOX for states that contribute 
significantly to nonattainment in downwind states and requires the 
significantly contributing states to submit SIP revisions that 
implement these budgets. States have the flexibility to choose which 
control measures to adopt to achieve the budgets, including 
participation in EPA-administered cap-and-trade programs addressing 
SO2, NOX -annual, and NOX -ozone 
season emissions.

B. Remand of the CAIR

    On July 11, 2008, the DC Circuit issued its decision to vacate and 
remand both CAIR and the associated CAIR FIPs in their entirety. See 
North Carolina v. EPA, 531 F.3d 836 (DC Cir. 2008). However, in 
response to EPA's petition for rehearing, the Court issued an order 
remanding CAIR to EPA without vacating either CAIR or the CAIR FIPs. 
The Court thereby left the EPA CAIR rule and CAIR SIPs and FIPs in 
place in order to ``temporarily preserve the environmental values 
covered by CAIR'' until EPA replaces it with a rule consistent with the 
court's opinion. See North Carolina v. EPA, 550 F.3d at 1178. The Court 
directed EPA to ``remedy CAIR's flaws'' consistent with its July 11, 
2008, opinion but declined to impose a schedule on EPA for completing 
that action. Because CAIR accordingly has been remanded to the Agency 
without vacatur, CAIR and the CAIR FIPs are currently in effect in 
subject states.

C. Regional Haze SIP Elements Potentially Affected by the CAIR Remand

    The following is a summary of the elements of the regional haze 
SIPs that are potentially affected by the remand of CAIR. Many states 
relied on CAIR as an alternative to BART for SO2 and 
NOX for subject EGUs, as allowed under the BART provisions 
at 40 CFR 51.308(e)(4). Additionally, several states established RPGs 
that reflect the improvement in visibility expected to result from 
controls planned for or already installed on sources within the state 
to meet the CAIR provisions for this implementation period for 
specified pollutants. Many states relied upon their own CAIR SIPs or 
the CAIR FIPs for their states to provide the legal requirements which 
leads to these planned controls, and did not include enforceable 
measures in the LTS in the regional haze SIP submission to ensure these 
reductions. States also submitted demonstrations showing that no 
additional controls on EGUs beyond CAIR would be reasonable for this 
implementation period. Due to EPA's

[[Page 33668]]

need to address the concerns of the Court as outlined in its decision 
remanding CAIR, EPA believes it would be inappropriate to fully approve 
states' LTSs that rely upon the emissions reductions predicted to 
result from CAIR to meet the BART requirement for EGUs or to meet the 
RPGs in the states' regional haze SIPs. For this reason, EPA cannot 
fully approve regional haze SIP revisions that rely on CAIR for 
emission reduction measures. EPA therefore proposes to grant limited 
approval and limited disapproval of the Tennessee SIP. The next section 
discusses how the Agency proposes to address these deficiencies.

D. Rationale and Scope of Proposed Limited Approval

    EPA is intending to propose to issue limited approvals of those 
regional haze SIP revisions that rely on CAIR to address the impact of 
emissions from a state's own EGUs. Limited approval results in approval 
of the entire regional haze submission and all its elements. EPA is 
taking this approach because an affected state's SIP will be stronger 
and more protective of the environment with the implementation of those 
measures by the state and having Federal approval and enforceability 
than it would without those measures being included in the state's SIP.
    EPA also intends to propose to issue limited disapprovals for 
regional haze SIP revisions that rely on CAIR concurrently with the 
proposals for limited approval. As explained in the 1992 Calcagni 
Memorandum, ``[t]hrough a limited approval, EPA [will] concurrently, or 
within a reasonable period of time thereafter, disapprove the rule * * 
* for not meeting all of the applicable requirements of the Act. * * * 
[T]he limited disapproval is a rulemaking action, and it is subject to 
notice and comment.'' Final limited disapproval of a SIP submittal does 
not affect the Federal enforceability of the measures in the subject 
SIP revision nor prevent state implementation of these measures. The 
legal effects of the final limited disapproval are to provide EPA the 
authority to issue a FIP at any time, and to obligate the Agency to 
take such action no more than two years after the effective date of the 
final limited disapproval action.

V. What is EPA's analysis of Tennessee's regional haze submittal?

    On April 4, 2008, TDEC's Division of Air Pollution Control 
submitted revisions to the Tennessee SIP to address regional haze in 
the State's Class I areas as required by EPA's RHR.

A. Affected Class I Areas

    Tennessee has two Class I areas within its borders: Great Smoky 
Mountains National Park and Joyce-Kilmer Slickrock Wilderness Area. 
These Class I areas also fall within the geographic boundaries of North 
Carolina. Therefore, both Tennessee and North Carolina are responsible 
for developing their own regional haze SIPs that address these Class I 
areas. The two states worked together to determine appropriate RPGs, 
including consulting with other states that impact the two Class I 
areas, as discussed in V.F.1. In addition, both Tennessee and North 
Carolina are responsible for describing their own long-term emission 
strategies, their role in the consultation processes, and how their 
particular state SIP meets the other requirements in EPA's regional 
haze regulations.
    The Tennessee regional haze SIP establishes RPGs for visibility 
improvement at each of these Class I areas and a LTS to achieve those 
RPGs within the first regional haze implementation period ending in 
2018. In developing the LTS for each area, Tennessee considered both 
emission sources inside and outside of Tennessee that may cause or 
contribute to visibility impairment in Tennessee's Class I areas. The 
State also identified and considered emission sources within Tennessee 
that may cause or contribute to visibility impairment in Class I areas 
in neighboring states as required by 40 CFR 51.308(d)(3). The VISTAS 
RPO worked with the State in developing the technical analyses used to 
make these determinations, including state-by-state contributions to 
visibility impairment in specific Class I areas, which included the two 
areas in Tennessee and those areas affected by emissions from 
Tennessee.

B. Determination of Baseline, Natural and Current Visibility Conditions

    As required by the RHR and in accordance with EPA's 2003 Natural 
Visibility Guidance, Tennessee calculated baseline/current and natural 
visibility conditions for each of its Class I areas, as summarized 
below (and as further described in sections III.B.1 and III.B.2. of 
EPA's TSD to this Federal Register action).
1. Estimating Natural Visibility Conditions
    Natural background visibility, as defined in EPA's 2003 Natural 
Visibility Guidance, is estimated by calculating the expected light 
extinction using default estimates of natural concentrations of fine 
particle components adjusted by site-specific estimates of humidity. 
This calculation uses the IMPROVE equation, which is a formula for 
estimating light extinction from the estimated natural concentrations 
of fine particle components (or from components measured by the IMPROVE 
monitors). As documented in EPA's 2003 Natural Visibility Guidance, EPA 
allows states to use ``refined'' or alternative approaches to 2003 EPA 
guidance to estimate the values that characterize the natural 
visibility conditions of the Class I areas. One alternative approach is 
to develop and justify the use of alternative estimates of natural 
concentrations of fine particle components. Another alternative is to 
use the ``new IMPROVE equation'' that was adopted for use by the 
IMPROVE Steering Committee in December 2005.\7\ The purpose of this 
refinement to the ``old IMPROVE equation'' is to provide more accurate 
estimates of the various factors that affect the calculation of light 
extinction. Tennessee opted to use the default estimates for the 
natural concentrations combined with the ``new IMPROVE equation,'' for 
all of its areas. Using this approach, natural visibility conditions 
using the new IMPROVE equation were calculated separately for each 
Class I area by VISTAS.
---------------------------------------------------------------------------

    \7\ The IMPROVE program is a cooperative measurement effort 
governed by a steering committee composed of representatives from 
Federal agencies (including representatives from EPA and the FLMs) 
and RPOs. The IMPROVE monitoring program was established in 1985 to 
aid the creation of Federal and State implementation plans for the 
protection of visibility in Class I areas. One of the objectives of 
IMPROVE is to identify chemical species and emission sources 
responsible for existing anthropogenic visibility impairment. The 
IMPROVE program has also been a key participant in visibility-
related research, including the advancement of monitoring 
instrumentation, analysis techniques, visibility modeling, policy 
formulation and source attribution field studies.
---------------------------------------------------------------------------

    The new IMPROVE equation takes into account the most recent review 
of the science \8\ and it accounts for the

[[Page 33669]]

effect of particle size distribution on light extinction efficiency of 
sulfate, nitrate, and organic carbon. It also adjusts the mass 
multiplier for organic carbon (particulate organic matter) by 
increasing it from 1.4 to 1.8. New terms are added to the equation to 
account for light extinction by sea salt and light absorption by 
gaseous nitrogen dioxide. Site-specific values are used for Rayleigh 
scattering (scattering of light due to atmospheric gases) to account 
for the site-specific effects of elevation and temperature. Separate 
relative humidity enhancement factors are used for small and large size 
distributions of ammonium sulfate and ammonium nitrate and for sea 
salt. The terms for the remaining contributors, elemental carbon 
(light-absorbing carbon), fine soil, and coarse mass terms, do not 
change between the original and new IMPROVE equations.
---------------------------------------------------------------------------

    \8\ The science behind the revised IMPROVE equation is 
summarized in Appendix B.2 of the Tennessee Regional Haze submittal 
and in numerous published papers. See for example: Hand, J.L., and 
Malm, W.C., 2006, Review of the IMPROVE Equation for Estimating 
Ambient Light Extinction Coefficients--Final Report. March 2006. 
Prepared for Interagency Monitoring of Protected Visual Environments 
(IMPROVE), Colorado State University, Cooperative Institute for 
Research in the Atmosphere, Fort Collins, Colorado. https://vista.cira.colostate.edu/improve/publications/GrayLit/016_IMPROVEeqReview/IMPROVEeqReview.htm; and Pitchford, Marc., 2006, 
Natural Haze Levels II: Application of the New IMPROVE Algorithm to 
Natural Species Concentrations Estimates. Final Report of the 
Natural Haze Levels II Committee to the RPO Monitoring/Data Analysis 
Workgroup. September 2006 https://vista.cira.colostate.edu/improve/Publications/GrayLit/029_NaturalCondII/naturalhazelevelsIIreport.ppt.
---------------------------------------------------------------------------

2. Estimating Baseline Conditions
    The Joyce Kilmer-Slickrock Wilderness Area does not contain an 
IMPROVE monitor. In cases where onsite monitoring is not available, 40 
CFR 51.308(d)(2)(i) requires states to use the most representative 
monitoring available for the 2000-2004 period to establish baseline 
visibility conditions, in consultation with EPA. Tennessee used and EPA 
concurs with the use of 2000-2004 data from the IMPROVE monitor at 
Great Smoky Mountains National Park for the Joyce Kilmer-Slickrock 
Wilderness Area. The Great Smoky Mountains National Park is nearest and 
contiguous to the Joyce Kilmer-Slickrock Wilderness Area, and the areas 
possess similar characteristics, such as meteorology and topography.
    TDEC estimated baseline visibility conditions at both Tennessee 
Class I areas using available monitoring data from a single IMPROVE 
monitoring site in the Great Smoky Mountains National Park. As 
explained in section III.B, for the first regional haze SIP, baseline 
visibility conditions are the same as current conditions. A five-year 
average of the 2000 to 2004 monitoring data was calculated for each of 
the 20 percent worst and 20 percent best visibility days at each 
Tennessee Class I area. IMPROVE data records for Great Smoky Mountains 
National Park for the period 2000 to 2004 meet the EPA requirements for 
data completeness. See page 2-8 of EPA's 2003 Tracking Progress 
Guidance. Table 3.3-1 from Appendix G of the Tennessee regional haze 
SIP, also provided in section III.B.3 of EPA's TSD to this action, 
lists the 20 percent best and worst days for the baseline period of 
2000-2004 for Great Smoky Mountains National Park. This data is also 
provided at the following Web site: https://www.metro4-sesarm.org/vistas/SesarmBext_20BW.htm.
3. Summary of Baseline and Natural Conditions
    For the Tennessee Class I areas, baseline visibility conditions on 
the 20 percent worst days are approximately 30 deciviews. Natural 
visibility in these areas is predicted to be approximately 11 deciviews 
on the 20 percent worst days. The natural and baseline conditions for 
Tennessee's Class I areas for both the 20 percent worst and best days 
are presented in Table 1 below.
---------------------------------------------------------------------------

    \9\ The term, ``dv,'' is the abbreviation for ``deciview.''

  Table 1--Natural Background and Baseline Conditions for the Tennessee
                              Class I Areas
------------------------------------------------------------------------
                                          Average for 20  Average for 20
              Class I area                 percent worst   percent best
                                           days (dv \9\)     days (dv)
------------------------------------------------------------------------
Natural Background Conditions:
    Great Smoky Mountains National Park.           11.05            4.54
    Joyce Kilmer-Slickrock Wilderness              11.05            4.54
     Area...............................
Baseline Visibility Conditions (2000-
 2004):
    Great Smoky Mountains National Park.           30.28           13.58
    Joyce Kilmer-Slickrock Wilderness              30.28           13.58
     Area...............................
------------------------------------------------------------------------

4. Uniform Rate of Progress
    In setting the RPGs, Tennessee considered the uniform rate of 
progress needed to reach natural visibility conditions by 2064 
(``glidepath'') and the emission reduction measures needed to achieve 
that rate of progress over the period of the SIP to meet the 
requirements of 40 CFR 51.308(d)(1)(i)(B). As explained in EPA's 
Reasonable Progress Guidance document, the uniform rate of progress is 
not a presumptive target, and RPGs may be greater, lesser, or 
equivalent to the glidepath.
    The State's implementation plan presents two sets of graphs, one 
for the 20 percent best days, and one for the 20 percent worst days, 
for its two Class I areas. Tennessee constructed the graph for the 
worst days (i.e., the glidepath) in accordance with EPA's 2003 Tracking 
Progress Guidance by plotting a straight graphical line from the 
baseline level of visibility impairment for 2000-2004 to the level of 
visibility conditions representing no anthropogenic impairment in 2064 
for its two areas. For the best days, the graph includes a horizontal, 
straight line spanning from baseline conditions in 2004 out to 2018 to 
depict no degradation in visibility over the implementation period of 
the SIP. Tennessee's SIP shows that the State's RPGs for its areas 
provide for improvement in visibility for the 20 percent worst days 
over the period of the implementation plan and ensure no degradation in 
visibility for the 20 percent best days over the same period, in 
accordance with 40 CFR 51.308(d)(1).
    For the Tennessee Class I areas, the overall visibility improvement 
necessary to reach natural conditions is the difference between 
baseline visibility of 30.28 deciviews for the 20 percent worst days 
and natural conditions of 11.05 deciviews, i.e., 19.23 deciviews. Over 
the 60-year period from 2004 to 2064, this would require an average 
improvement of 0.321 deciviews per year to reach natural conditions. 
Hence, for the 14-year period from 2004 to 2018, in order to achieve 
visibility improvements at least equivalent to the uniform rate of 
progress for the 20 percent worst days at Great Smoky Mountain National 
Park and the Joyce Kilmer-Slickrock Wilderness Area, Tennessee would 
need to project at least 4.49 deciviews over the first implementation 
period (i.e., 0.321 deciviews x 14 years = 4.49 deciviews) of 
visibility improvement from the 30.28 deciviews baseline in 2004, 
resulting in visibility levels at or below 25.79 deciviews in 2018. As 
discussed below in section V.C.7,

[[Page 33670]]

``Reasonable Progress Goals,'' Tennessee projects a 6.78 deciview 
improvement to visibility from the 30.28 deciview baseline to 23.50 
deciviews in 2018 for the 20 percent most impaired days, and a 1.47 
deciview improvement to 12.11 deciviews from the baseline visibility of 
13.58 deciviews for the 20 percent least impaired days.

C. Long-Term Strategy/Strategies

    As described in section III.E of this action, the LTS is a 
compilation of state-specific control measures relied on by the state 
for achieving its RPGs. Tennessee's LTS for the first implementation 
period addresses the emissions reductions from Federal, state, and 
local controls that take effect in the State from the end of the 
baseline period starting in 2004 until 2018. The Tennessee LTS was 
developed by the State, in coordination with the VISTAS RPO, through an 
evaluation of the following components: (1) Identification of the 
emission units within Tennessee and in surrounding states that likely 
have the largest impacts currently on visibility at the State's two 
Class I areas; (2) estimation of emissions reductions for 2018 based on 
all controls required or expected under Federal and state regulations 
for the 2004-2018 period (including BART); (3) comparison of projected 
visibility improvement with the uniform rate of progress for the 
State's Class I areas; and (4) application of the four statutory 
factors in the reasonable progress analysis for the identified emission 
units to determine if additional reasonable controls were required.
    CAIR is also an element of Tennessee's LTS. CAIR rule revisions 
were approved into the Tennessee SIP in 2007 and 2009. See 72 FR 46388 
(Aug. 20, 2007); 74 FR 61535 (Nov. 25, 2009). Tennessee opted to rely 
on CAIR emission reduction requirements to satisfy the BART 
requirements for SO2 and NOX from EGUs. See 40 
CFR 51.308(e)(4). Therefore, Tennessee only required its BART-eligible 
EGUs to evaluate PM emissions for determining whether they are subject 
to BART, and, if applicable, for performing a BART control assessment. 
See section III.D. of this notice for further details. Additionally, as 
discussed below in section V.C.5, Tennessee concluded that no 
additional controls beyond CAIR are reasonable for reasonable progress 
for its EGUs for this first implementation period. Prior to the remand 
of CAIR, EPA believed the State's reliance on CAIR for specific BART 
and reasonable progress provisions affecting its EGUs was adequate, as 
detailed later in this notice. As explained in section IV. of this 
notice, the Agency proposes today to issue a limited approval and a 
proposed limited disapproval of the State's regional haze SIP revision.
1. Emissions Inventory for 2018 With Federal and State Control 
Requirements
    The emissions inventory used in the regional haze technical 
analyses was developed by VISTAS with assistance from Tennessee. The 
2018 emissions inventory was developed by projecting 2002 emissions and 
applying reductions expected from Federal and state regulations 
affecting the emissions of VOC and the visibility-impairing pollutants 
NOX, PM, and SO2. The BART Guidelines direct 
states to exercise judgment in deciding whether VOC and NH3 
impair visibility in their Class I area(s). As discussed further in 
section V.C.3, VISTAS performed modeling sensitivity analyses, which 
demonstrated that anthropogenic emissions of VOC and NH3 do 
not significantly impair visibility in the VISTAS region. Thus, while 
emissions inventories were also developed for NH3 and VOC, 
and applicable Federal VOC reductions were incorporated into 
Tennessee's regional haze analyses, Tennessee did not further evaluate 
NH3 and VOC emissions sources for potential controls under 
BART or reasonable progress.
    VISTAS developed emissions for five inventory source 
classifications: Stationary point and area sources, off-road and on-
road mobile sources, and biogenic sources. Stationary point sources are 
those sources that emit greater than a specified tonnage per year, 
depending on the pollutant, with data provided at the facility level. 
Stationary area sources are those sources whose individual emissions 
are relatively small, but due to the large number of these sources, the 
collective emissions from the source cate