```

[Federal Register Volume 77, Number 48 (Monday, March 12, 2012)]
[Rules and Regulations]
[Pages 14604-14677]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-4493]

[[Page 14603]]

Vol. 77

Monday,

No. 48

March 12, 2012

Part II

Environmental Protection Agency

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40 CFR Part 52

Approval and Promulgation of Implementation Plans; Arkansas; Regional 
Haze State Implementation Plan; Interstate Transport State 
Implementation Plan To Address Pollution Affecting Visibility and 
Regional Haze; Final Rule

Federal Register / Vol. 77 , No. 48 / Monday, March 12, 2012 / Rules 
and Regulations

[[Page 14604]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R06-OAR-2008-0727; FRL-9637-4]

Approval and Promulgation of Implementation Plans; Arkansas; 
Regional Haze State Implementation Plan; Interstate Transport State 
Implementation Plan To Address Pollution Affecting Visibility and 
Regional Haze

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The EPA is partially approving and partially disapproving a 
revision to the Arkansas State Implementation Plan (SIP) intended to 
address the regional haze (RH) requirements of the Clean Air Act (CAA 
or Act). In addition, EPA is partially approving and partially 
disapproving the portion of the Arkansas Interstate Transport SIP 
submittal that addresses the visibility requirement of section 
110(a)(2)(D)(i)(II) for the 1997 8-hour ozone and 1997 fine particulate 
matter (PM2.5) national ambient air quality standards 
(NAAQS) that the Arkansas SIP contain adequate provisions to prohibit 
emissions from interfering with measures required in another state to 
protect visibility. EPA is approving certain core elements of the RH 
SIP including: identification of affected Class I areas; determination 
of baseline and natural visibility conditions; determination of Uniform 
Rate of Progress (URP); reasonable progress goal (RPG) consultation and 
long term strategy (LTS) consultation; coordination of RH and 
reasonably attributable visibility impairment (RAVI); regional haze 
monitoring strategy and other SIP requirements under 40 CFR 
51.308(d)(4); commitment to submit periodic regional haze SIP revisions 
and periodic progress reports describing progress towards the RPGs; 
commitment to make a determination of the adequacy of the existing SIP 
at the time a progress report is submitted; and consultation and 
coordination with Federal land managers (FLMs). EPA is partially 
approving and partially disapproving portions of other core elements of 
the SIP including: identification of best available retrofit technology 
(BART) eligible sources and subject to BART sources; requirements for 
BART; Chapter 15 of the Air Pollution Control and Ecology Commission 
(APCEC) Regulation No. 19, also known as the State's RH Rule; and the 
LTS. EPA is disapproving Arkansas's reasonable progress goals (RPGs) 
required under 40 CFR 51.308(d)(1). This action is being taken under 
section 110 and part C of the CAA.

DATES: This final rule is effective on April 11, 2012.

ADDRESSES: EPA has established a docket for this action under Docket ID 
No. EPA-R06-OAR-2008-0727. All documents in the docket are listed in 
the Federal e-Rulemaking portal index at http://www.regulations.gov and 
are available either electronically at http://www.regulations.gov or in 
hard copy at EPA Region 6, 1445 Ross Ave., Dallas, TX 75202-2733. To 
inspect the hard copy materials, please schedule an appointment during 
normal business hours with the contact listed in the FOR FURTHER 
INFORMATION CONTACT section. A reasonable fee may be charged for 
copies.

FOR FURTHER INFORMATION CONTACT: Ms. Dayana Medina, Air Planning 
Section (6PD-L), Environmental Protection Agency, Region 6, 1445 Ross 
Avenue, Suite 700, Dallas, Texas 75202-2733, telephone 214-665-7241; 
fax number 214-665-7263; email address medina.dayana@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document wherever ``we,'' 
``us,'' ``our,'' or ``the Agency'' is used, we mean the EPA.

Overview

    The CAA requires that states develop and implement SIPs to reduce 
the pollution that causes visibility impairment over a wide geographic 
area, known as Regional Haze (RH). CAA sections 110(a) and 169A. 
Arkansas submitted a RH plan to us on September 23, 2008, and August 3, 
2010, and submitted supplemental information on September 27, 2011. On 
October 17, 2011, we proposed to partially approve and partially 
disapprove certain elements of Arkansas's SIP.\1\ Today, we are taking 
final action by partially approving and partially disapproving the 
elements of Arkansas's RH SIP addressed in our proposed rule.
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    \1\ 76 FR 64186.
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    In addition to the RH requirements, CAA section 110(a)(2)(D)(i)(II) 
requires that the Arkansas SIP ensure that emissions from sources 
within Arkansas do not interfere with the SIP of any other state under 
part C of the CAA to protect visibility. This requirement is commonly 
referred to as the visibility prong of ``interstate transport,'' which 
is also called the ``good neighbor'' provision of the CAA. Arkansas 
submitted a SIP to meet the requirements of interstate transport for 
the 1997 8-hour ozone and PM2.5 NAAQS on April 2, 2008, and 
supplemented it on September 27, 2011. On October 17, 2011, we proposed 
to partially approve and partially disapprove this submission as it 
relied upon the State's RH Rule that we were proposing to partially 
approve and partially disapprove. Id. Because the Interstate Transport 
SIP is conditioned upon the BART determinations in the RH SIP, we are 
also taking final action by partially approving and partially 
disapproving elements of Arkansas's Interstate Transport SIP addressed 
in our proposed rule.
    Arkansas submitted Chapter 15 of APCEC Regulation No. 19, its State 
RH Rule that addresses Arkansas's RH program, to address the 
requirements in both its RH SIP and its Interstate Transport SIP. In 
both the RH SIP and the Interstate Transport SIP, Arkansas adopted BART 
emission limits for certain sources to meet the requirements of both 
SIPs as stated in the State RH Rule. Based upon public comment, we are 
disapproving the portion of the BART compliance provision found in the 
State's RH Rule, Chapter 15 of APCEC Regulation No. 19, at Reg. 19.1504 
(B), which requires each source subject to BART to install and operate 
BART no later than six years after the effective date of Arkansas's RH 
Rule for both the RH SIP and the Interstate Transport SIP. Because of 
this disapproval, compliance with Arkansas's BART emission limitations 
is within five years of approval of Arkansas RH SIP by EPA.
    For a RH SIP, the process of establishing BART emission limitations 
can be logically broken down into three steps. First, states identify 
those sources which meet the definition of ``BART eligible source'' set 
forth in 40 CFR 51.301. Second, states determine whether such sources 
``emit any air pollutant which may reasonably be anticipated to cause 
or contribute to any impairment of visibility in any such area'' (a 
source which fits this description is ``subject to BART''). Third, for 
each source subject to BART, states then identify the appropriate type 
and the level of control for reducing emissions by conducting a five-
step analysis: Step 1: Identify All Available Retrofit Control 
Technologies, Step 2: Eliminate Technically Infeasible Options, Step 3: 
Evaluate Control Effectiveness of Remaining Control Technologies, Step 
4: Evaluate Impacts and Document the Results, and Step 5: Evaluate 
Visibility Impacts.

[[Page 14605]]

    We agree with Arkansas's identification of sources that are BART 
eligible, with the exception of the 6A Boiler at the Georgia-Pacific 
Crossett Mill, which we find to be BART eligible. We also agree with 
Arkansas's identification of subject to BART sources, with the 
exception of the 6A and 9A Boilers at the Georgia-Pacific Crossett 
Mill, which we find to be subject to BART. In addition, we are 
approving a number of BART determinations from Arkansas's RH SIP. We 
are not able to approve the following BART determinations made by 
Arkansas: the sulfur dioxide (SO2), nitrogen dioxide 
(NOX), and particulate matter (PM) BART determinations for 
the Arkansas Electric Cooperative Corporation (AECC) Bailey Plant Unit 
1 and the AECC McClellan Plant Unit 1; the SO2 and 
NOX BART determinations for the American Electric Power 
(AEP) Flint Creek Plant Boiler No. 1; the NOX BART 
determination for the natural gas firing scenario and the 
SO2, NOX, and PM BART determinations for the fuel 
oil firing scenario for the Entergy Lake Catherine Plant Unit 4; the 
SO2 and NOX BART determinations for both the 
bituminous and sub-bituminous coal firing scenarios for the Entergy 
White Bluff Plant Units 1 and 2; the BART determination for the Entergy 
White Bluff Plant Auxiliary Boiler; the SO2 and 
NOX BART determinations for the Domtar Ashdown Mill Power 
Boiler No. 1; and the SO2, NOX and PM BART 
determinations for the Domtar Ashdown Mill Power Boiler No. 2. In 
reviewing the State's BART determinations for these pollutants and 
units, we found that the State did not satisfy all the regulatory and 
statutory requirements in making these BART determinations. We have 
therefore determined it is appropriate to finalize our proposed 
disapproval of the State's BART determinations for these units, because 
we conclude that the flaws and omissions in the State's BART analyses 
were significant, and that the State therefore lacked adequate record 
support and a reasoned basis for its analyses, as required by the RH 
Rule (RHR). As we previously noted, Arkansas submitted Chapter 15 of 
APCEC Regulation No. 19, also known as the State's RH Rule, as a SIP 
revision to address both RH and the visibility transport requirements. 
With respect to RH, we are partially approving and partially 
disapproving Chapter 15 of APCEC Regulation No. 19, such that our 
disapproval is of those portions of the State's RH Rule that correspond 
to portions of the Arkansas RH SIP we are disapproving. In particular, 
we note that based upon public comment, we also are disapproving the 
portion of the BART compliance provision found in Chapter 15 of APCEC 
Regulation No. 19, at Reg. 19.1504(B), which requires each source 
subject to BART to install and operate BART requirements no later than 
six years after the effective date of the State's regulation. We are 
approving the portion of the BART compliance provision that requires 
each Arkansas subject to BART source to install and operate BART as 
expeditiously as practicable, but in no event later than five years 
after EPA approval of the Arkansas RH SIP, for those sources' BART 
determinations we are approving. We find that this is consistent with 
the requirements under 40 CFR 51.308(e)(iv). Arkansas's inclusion of 
the compliance provision that would require Arkansas subject to BART 
sources to install and operate BART no later than six years after the 
effective date of the State's regulation (if such date takes place 
before five years from EPA approval of the Arkansas RH SIP) is not a 
required element of the RH SIPs to be developed and submitted by states 
pursuant to section 169 of the CAA. We are also partially approving and 
partially disapproving the State's submitted LTS because it relies on 
portions of the RH SIP we are disapproving, including some of 
Arkansas's BART emission limits. We are disapproving the State's RPGs 
under 40 CFR 51.308(d)(1) because Arkansas did not consider the four 
factors that states are required to consider in establishing RPGs under 
the CAA and 40 CFR 51.308(d)(1)(A).
    We are approving the remaining sections of the RH SIP submission. 
This includes certain core elements of the SIP, including Arkansas's 
(1) Identification of affected Class I areas; (2) determination of 
baseline and natural visibility conditions; (3) determination of the 
URP; (4) RPG consultation and LTS consultation; (5) coordination of 
regional haze and reasonably attributable visibility impairment; (6) 
monitoring strategy and other implementation requirements; (7) 
commitment to submit periodic RH SIP revisions and periodic progress 
reports describing progress towards the RPGs; (8) commitment to make a 
determination of the adequacy of the existing SIP at the time a 
progress report is submitted; (9) coordination with states and FLMs; 
and (10) the following BART determinations from Arkansas's RH SIP:
     The PM BART determination for the AEP Flint Creek Plant 
Boiler No. 1.
     The SO2 and PM BART determinations for the 
natural gas firing scenario for the Entergy Lake Catherine Plant Unit 
4.
     The PM BART determinations for both the bituminous and 
sub-bituminous coal firing scenarios for the Entergy White Bluff Plant 
Units 1 and 2.
     The PM BART determination for the Domtar Ashdown Mill 
Power Boiler No. 1.
    Arkansas stated in its April 2, 2008 submittal that it is relying 
on Chapter 15 of APCEC Regulation No. 19, also known as the State's RH 
Rule, to satisfy the requirements of section 110(a)(2)(D)(i)(II) that 
emissions from Arkansas sources not interfere with measures required in 
the SIP of any other state under part C of the CAA to protect 
visibility. The Arkansas Department of Environmental Quality (ADEQ) 
also stated in its April 2, 2008, submittal that it is not possible to 
assess whether there is any interference with the measures in the 
applicable SIP for another state designed to protect visibility for the 
8-hour ozone and PM2.5 NAAQS until ADEQ submits and EPA 
approves Arkansas's RH SIP. We proposed to partially approve and 
partially disapprove this submission as it relied upon the State's RH 
Rule that we were proposing to partially approve and partially 
disapprove. In developing their RH SIP and RPGs, Arkansas and 
potentially impacted States collaborated through the Central Regional 
Air Planning (CENRAP) association. Each state developed its RH Plans 
and RPGs based on the CENRAP modeling. The CENRAP modeling was based in 
part on the emissions reductions each state intended to achieve by 
2018. Some of the emissions reductions included in the CENRAP's 
modeling and thus relied upon by other states, were from BART controls 
on Arkansas subject to BART sources. Compliance with these BART 
requirements will ensure that Arkansas obtains its share of the 
emission reductions relied upon by other states to meet the RPGs for 
their Class I areas. As already previously discussed in this final 
rulemaking, Arkansas submitted Chapter 15 of APCEC Regulation No. 19, 
also known as the State's RH Rule, as a SIP revision to address both RH 
and the visibility transport requirements. With respect to the 
visibility interstate transport SIP, we are partially approving and 
partially disapproving the submitted Chapter 15 of APCEC Regulation No. 
19, such that our disapproval is of those portions that correspond to 
the submitted BART determinations we are disapproving. In response to 
public comment, we note that we also are disapproving the portion of 
the BART compliance

[[Page 14606]]

provision found in the APCEC Regulation No. 19, at Reg. 19.1504(B), 
which requires each source subject to BART to install and operate BART 
no later than six years after the effective date of the State's 
regulation. Since compliance of Arkansas's subject to BART sources with 
BART requirements now is solely dependent upon our approval of the RH 
SIP, and since we are disapproving the portion of the RH SIP which 
includes some of Arkansas's BART determinations, a portion of the 
emission reductions committed to by Arkansas and relied upon by other 
states will not be realized. Consequently, Arkansas's emissions will 
interfere with other states' SIPs to protect visibility. Therefore, we 
are partially approving and partially disapproving the portion of the 
Arkansas Interstate Transport SIP submittal that addresses the 
visibility requirement of section 110(a)(2)(D)(i)(II) that emissions 
from Arkansas sources not interfere with measures required in the SIP 
of any other state under part C of the CAA to protect visibility.
    Under the CAA,\2\ we must, within 24 months following a final 
disapproval, either approve a SIP or promulgate a Federal 
Implementation Plan (FIP). We will of course consider, and would 
prefer, approving a SIP if the state submits a revised plan that we can 
approve before the expiration of the mandatory FIP clock for the 
portions of the SIP we are disapproving in this rulemaking action.
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    \2\ CAA section 110(c)(1).
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    We originally provided a 30 day public comment period for this 
action, which we extended after receiving several requests for an 
extension on the comment period. We held a 66 day public comment period 
for this action. Many public commenters disagreed with several aspects 
of our proposal, expressing the belief that we should approve either 
more portions of the Arkansas RH SIP or the SIP in its entirety. We 
also received public comments agreeing with several aspects of our 
proposal, expressing the belief that we should disapprove either more 
portions of the Arkansas RH SIP or the SIP in its entirety. All public 
comments and our responses are discussed in more detail in section III 
of this final rulemaking action.
    This action is being taken under section 110 and part C of the CAA.

Table of Contents

I. Summary of Our Proposal
    A. Regional Haze
    B. Interstate Transport of Pollutants and Visibility Protection
II. Final Decision
    A. Regional Haze
    B. Interstate Transport of Pollutants and Visibility Protection
III. Public Comments Received and Our Responses
    A. Comments on Presumptive Emission Limits
    B. Comments on Reasonable Progress Goals and Long Term Strategy
    C. Comments on BART
    1. Evaluation of the Most Stringent Level of Control in the BART 
Analysis
    2. Evaluation of Post-Combustion Controls in the BART Analysis
    3. Comments on the State's PM BART Emission Limits We Proposed 
to Approve
    4. Comments on the Capacity Factor Used in the State's BART 
Analyses for Entergy Lake Catherine and White Bluff
    5. Comments on the State's Cost Evaluations
    6. Comments on the August 2008 Revised BART Analysis for White 
Bluff
    7. Other Comments Related to BART
    D. Comments on the Arkansas Pollution Control and Ecology 
Commission Variance for Subject to BART Sources
    E. Comments on BART and the Forthcoming MACT Requirements
    F. Comments on Modeling
    G. Comments on Legal Issues
    1. Comments on Regional Haze
    2. Comments on Interstate Transport and Visibility
    H. Other Comments
    I. Comments Requesting an Extension to the Public Comment Period
IV. Statutory and Executive Order Reviews

I. Summary of Our Proposal

    On October 17, 2011, we published the proposal on which we are now 
taking final action.\3\ We proposed to partially approve and partially 
disapprove Arkansas's RH SIP revision submitted on September 23, 2008, 
August 3, 2010, and supplemented on September 27, 2011. We also 
proposed to partially approve and partially disapprove a portion of a 
SIP revision we received from the State of Arkansas on April 2, 2008, 
as supplemented on September 27, 2011, for the purpose of addressing 
the ``good neighbor'' provisions of the CAA section 110(a)(2)(D)(i)(II) 
with respect to visibility for the 1997 8-hour ozone NAAQS and the 
PM2.5 NAAQS.
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    \3\ 76 FR 64186.
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A. Regional Haze

    We proposed to approve the State's identification of BART-eligible 
sources, with the exception of the 6A Boiler at the Georgia-Pacific 
Crossett Mill, which we find to be BART-eligible. We proposed to 
approve the State's identification of subject to BART sources, with the 
exception of the 6A and 9A Boilers at the Georgia-Pacific Crossett 
Mill, which we find to be subject to BART. We also proposed to approve 
certain core elements of the SIP, including Arkansas's (1) 
identification of affected Class I areas; (2) determination of baseline 
and natural visibility conditions; (3) determination of the URP; (4) 
RPG consultation and LTS consultation; (5) coordination of regional 
haze and reasonably attributable visibility impairment; (6) monitoring 
strategy and other implementation requirements; (7) commitment to 
submit periodic RH SIP revisions and periodic progress reports 
describing progress towards the RPGs; (8) commitment to make a 
determination of the adequacy of the existing SIP at the time a 
progress report is submitted; (9) coordination with states and FLMs; 
and (10) the following BART determinations from Arkansas's RH SIP: the 
PM BART determination for the AEP Flint Creek Plant Boiler No. 1; the 
SO2 and PM BART determinations for the natural gas firing 
scenario for the Entergy Lake Catherine Plant Unit 4; the PM BART 
determinations for both the bituminous and sub-bituminous coal firing 
scenarios for the Entergy White Bluff Plant Units 1 and 2; and PM BART 
determination for the Domtar Ashdown Mill Power Boiler No. 1.
    We proposed to disapprove Arkansas's SO2, 
NOX, and PM BART determinations for the AECC Bailey Plant 
Unit 1 and the AECC McClellan Plant Unit 1; the SO2 and 
NOX BART determinations for the AEP Flint Creek Plant Boiler 
No. 1; the NOX BART determination for the natural gas firing 
scenario and the SO2, NOX, and PM BART 
determinations for the fuel oil firing scenario for the Entergy Lake 
Catherine Plant Unit 4; the SO2 and NOX BART 
determinations for both the bituminous and sub-bituminous coal firing 
scenarios for the Entergy White Bluff Plant Units 1 and 2; the BART 
determination for the Entergy White Bluff Plant Auxiliary Boiler; the 
SO2 and NOX BART determinations for the Domtar 
Ashdown Mill Power Boiler No. 1; and the SO2, NOX 
and PM BART determinations for the Domtar Ashdown Mill Power Boiler No. 
2 because they do not comply with our regulations under 40 CFR 
51.308(e). We also proposed to partially approve and partially 
disapprove the Arkansas RH Rule, Chapter 15 of APCEC Regulation No. 19, 
such that our proposed disapproval was of those portions of the State's 
RH Rule that correspond to portions of the Arkansas RH SIP we were 
proposing to disapprove. We also proposed to partially approve and 
partially disapprove the LTS under 40 CFR

[[Page 14607]]

51.308(d)(3) because Arkansas has not shown that the strategy is 
adequate to achieve the RPGs set by Arkansas and by other nearby 
states.
    We proposed to disapprove the State's RPGs under 40 CFR 
51.308(d)(1) because Arkansas did not consider the four factors states 
are required to consider in establishing RPGs under the CAA and 40 CFR 
51.308(d)(1)(A).

B. Interstate Transport of Pollutants and Visibility Protection

    We proposed to partially approve and partially disapprove a portion 
of a SIP revision we received from the State of Arkansas on April 2, 
2008, as supplemented on September 27, 2011, for the purpose of 
addressing the ``good neighbor'' provisions of the CAA section 
110(a)(2)(D)(i) with respect to visibility for the 1997 8-hour ozone 
NAAQS and the PM2.5 NAAQS. This SIP revision addressed the 
requirement of section 110(a)(2)(D)(i)(II) that emissions from Arkansas 
sources do not interfere with measures required in the SIP of any other 
state under part C of the CAA to protect visibility. ADEQ participated 
in the CENRAP visibility modeling development that assumed certain 
SO2, NOX, and PM reductions from Arkansas's BART 
sources. Compliance with these BART requirements will ensure that 
Arkansas obtains its share of the emission reductions relied upon by 
other states to meet the RPGs for their Class I areas. Since compliance 
of Arkansas's subject to BART sources with BART requirements is 
dependent upon our approval of the RH SIP, and since we proposed to 
disapprove the portion of the RH SIP which includes some of Arkansas's 
BART determinations, a portion of the emission reductions committed to 
by Arkansas and relied upon by other states will not be realized and, 
as a consequence, Arkansas's emissions will interfere with other 
states' SIPs to protect visibility.

II. Final Decision

A. Regional Haze

    With one exception, we are finalizing our action as proposed. As 
discussed below, based upon public comment, we are adjusting our action 
on the Arkansas RH Rule. We are partially approving and partially 
disapproving the Arkansas RH SIP revision submitted on September 23, 
2008, August 3, 2010, and supplemented on September 27, 2011. We are 
approving Arkansas's identification of sources that are BART eligible, 
with the exception of the 6A Boiler at the Georgia-Pacific Crossett 
Mill, which we find to be BART-eligible. We are also approving 
Arkansas's identification of subject to BART sources, with the 
exception of the 6A and 9A Boilers at the Georgia-Pacific Crossett 
Mill, which we find to be subject to BART.
    We are disapproving Arkansas's SO2, NOX, and 
PM BART determinations for the AECC Bailey Plant Unit 1 and the AECC 
McClellan Plant Unit 1; the SO2 and NOX BART 
determinations for the AEP Flint Creek Plant Boiler No. 1; the 
NOX BART determination for the natural gas firing scenario 
and the SO2, NOX, and PM BART determinations for 
the fuel oil firing scenario for the Entergy Lake Catherine Plant Unit 
4; the SO2 and NOX BART determinations for both 
the bituminous and sub-bituminous coal firing scenarios for the Entergy 
White Bluff Plant Units 1 and 2; the BART determination for the Entergy 
White Bluff Plant Auxiliary Boiler; the SO2 and 
NOX BART determinations for the Domtar Ashdown Mill Power 
Boiler No. 1; and the SO2, NOX and PM BART 
determinations for the Domtar Ashdown Mill Power Boiler No. 2. With 
respect to RH, we are partially approving and partially disapproving 
the Arkansas RH Rule, Chapter 15 of APCEC Regulation No. 19, such that 
our disapproval is of those portions of the State's RH Rule that 
correspond to portions of the Arkansas RH SIP we are disapproving and 
our approval is of the remaining portions. We do note that in response 
to comments received, we are making one change to the portions of the 
Arkansas RH Rule we are approving from what we proposed to approve in 
our October 17, 2011, proposed rulemaking. Specifically, in our 
proposed rulemaking, we proposed to approve Reg. 19.1504(B), which 
requires Arkansas's subject to BART sources to ``install and operate 
BART as expeditiously as practicable, but in no event later than 6 
years after the effective date of [the State RH Rule] or 5 years after 
EPA approval of the Arkansas Regional Haze State Implementation Plan, 
whichever comes first.'' As discussed in more detail in our response to 
comments, because the State revised its rule to delete the provision 
that would require Arkansas's subject to BART sources to comply with 
BART within 6 years of the effective date of the State RH Rule, we are 
disapproving this portion of the BART compliance provision found in 
Chapter 15 of APCEC Regulation No. 19. We are partially approving and 
partially disapproving the portion of the BART compliance provision 
that requires each Arkansas subject to BART source to install and 
operate BART as expeditiously as practicable, but in no event later 
than five years after EPA approval of the Arkansas RH SIP. The 
disapproval is of those portions of the State's RH Rule that correspond 
to portions of the Arkansas RH SIP we are disapproving. We find that 
this is consistent with the requirements under 40 CFR 51.308(e)(iv). We 
are partially approving and partially disapproving the LTS under 40 CFR 
51.308(d)(3). We are disapproving the State's RPGs under 40 CFR 
51.308(d)(1).
    We are approving the remaining sections of the RH SIP submission. 
This includes certain core elements of the SIP, including Arkansas's 
(1) identification of affected Class I areas; (2) determination of 
baseline and natural visibility conditions; (3) determination of the 
URP; (4) RPG consultation and LTS consultation; (5) coordination of 
regional haze and reasonably attributable visibility impairment; (6) 
monitoring strategy and other implementation requirements; (7) 
commitment to submit periodic RH SIP revisions and periodic progress 
reports describing progress towards the RPGs; (8) commitment to make a 
determination of the adequacy of the existing SIP at the time a 
progress report is submitted; (9) coordination with states and FLMs; 
and (10) the following BART determinations from Arkansas's RH SIP:
     The PM BART determination for the AEP Flint Creek Plant 
Boiler No. 1.
     The SO2 and PM BART determinations for the 
natural gas firing scenario for the Entergy Lake Catherine Plant Unit 
4.
     The PM BART determinations for both the bituminous and 
sub-bituminous coal firing scenarios for the Entergy White Bluff Plant 
Units 1 and 2.
     The PM BART determination for the Domtar Ashdown Mill 
Power Boiler No. 1.

B. Interstate Transport of Pollutants and Visibility Protection

    We are partially approving and partially disapproving a portion of 
a SIP revision we received from the State of Arkansas on April 2, 2008, 
as supplemented on September 27, 2011, for the purpose of addressing 
the ``good neighbor'' provisions of the CAA section 110(a)(2)(D)(i) 
with respect to visibility for the 1997 8-hour ozone NAAQS and the 
PM2.5 NAAQS. Because Arkansas relied on Chapter 15 of APCEC 
Regulation No. 19, to satisfy the requirements of section 
110(a)(2)(D)(i)(II) that emissions from Arkansas sources not interfere 
with

[[Page 14608]]

measures required in the SIP of any other state under part C of the CAA 
to protect visibility, we are partially approving and partially 
disapproving the submitted Chapter 15 of APCEC Regulation No. 19, such 
that our disapproval is of those portions that correspond to the 
submitted BART determinations we are disapproving. In response to 
public comment, we note that we also are disapproving the portion of 
the BART compliance provision found in the APCEC Regulation No. 19, at 
Reg. 19.1504(B), which requires each source subject to BART to install 
and operate BART no later than six years after the effective date of 
the State's regulation. Since compliance of Arkansas's subject to BART 
sources with BART requirements now is solely dependent upon our 
approval of the RH SIP, and since we are disapproving the portion of 
the RH SIP which includes some of Arkansas's BART determinations, a 
portion of the emission reductions committed to by Arkansas and relied 
upon by other states will not be realized and, as a consequence, 
Arkansas's emissions will interfere with other states' SIPs to protect 
visibility. Therefore, we are partially approving and partially 
disapproving the portion of the Arkansas Interstate Transport SIP 
submittal that addresses the visibility requirement of section 
110(a)(2)(D)(i)(II) that emissions from Arkansas sources not interfere 
with measures required in the SIP of any other state under part C of 
the CAA to protect visibility.

III. Public Comments Received and Our Responses

    During the public notice and comment period, we received 13 comment 
letters both supporting and opposing our proposal. We received comments 
from the ADEQ, the Utah Department of Environmental Quality (UDEQ), the 
National Park Service, the Sierra Club, Entergy Arkansas Inc., the 
American Electric Power/Southwestern Electric Power Company (AEP-
SWEPCO), the Arkansas Electric Cooperative Corporation, Domtar 
Industries Inc., Nucor Steel-Arkansas, the Competitive Enterprise 
Institute, the Utility Air Regulatory Group, PacifiCorp Energy, and the 
Energy and Environmental Alliance of Arkansas. The comments we received 
opposing our proposal contended that we had either overstepped our 
bounds in proposing a partial disapproval or that we had not gone far 
enough in our action and should fully disapprove Arkansas's RH SIP. 
Many of the comments received are similar in nature and are grouped 
together accordingly. Thus, many of the comments you will read are 
representative of more than one comment letter. The comments are 
summarized and addressed below. The full text received from these 
commenters is included in the docket associated with this action.

A. Comments on Presumptive Emission Limits

    Comment: The SO2 and NOX BART determinations 
for the AEP Flint Creek Boiler No. 1 and Entergy White Bluff Plant 
Units 1 and 2 meet the presumptive BART limits established in 40 CFR 
part 51, appendix Y (BART Guidelines). In the Arkansas RH proposal, EPA 
did not justify its decision that the presumptive BART limits are 
unacceptable. EPA is insisting on a five factor analysis even when a 
source can meet the presumptive limits. EPA's current interpretation of 
the presumptive BART limits makes the presumptive BART limits 
meaningless, contrary to the requirements of the CAA and the clear 
intent of the BART Rule. The CAA singles out electric generating units 
(EGUs) located at 750 megawatt (MW) power plants for specific BART 
controls (42 U.S.C. 7491(b)(2)), and EPA adopted the presumptive BART 
limits to establish the specific control levels required for these 
EGUs. Since EPA went through extensive analysis to establish 
presumptive BART limits, the only rational explanation is that EPA 
intended for those limits to be meaningful. EPA is rationalizing its 
decision on the Arkansas RH SIP as if the presumptive BART limits were 
no longer a binding regulation, and there is concern that EPA is 
attempting to establish new, more stringent presumptive BART limits 
through case-by-case disapprovals of state BART determinations. Unless 
and until EPA goes through notice and comment rulemaking to remove the 
presumptive emission limits and establish other requirements consistent 
with the CAA, the presumptive BART limits in the promulgated BART Rule 
continue to establish the requirement that states must meet in their 
regional haze SIPs for large coal-fired EGUs and EPA must approve a 
state's BART determination if it meets the presumptive regulatory 
limits.
    Response: Our application of the presumptive BART limits in our 
proposed rulemaking on the Arkansas RH SIP gives proper treatment of 
presumptive BART limits and is consistent with the requirements of the 
CAA and the intent of the BART Rule.
    We note that the states generally have broad authority to decide 
appropriate BART controls. However, the CAA gives EPA a more active 
role in establishing BART emission limits for large power plants.\4\ 
The CAA states the following regarding emission limits for fossil-fuel 
fired generating power plants having a total generating capacity in 
excess of 750 MW:
---------------------------------------------------------------------------

    \4\ 69 FR 39129 and CAA section 169(a)(4).
---------------------------------------------------------------------------

    ``In the case of a fossil-fuel fired generating power plant having 
a total generating capacity in excess of 750 megawatts, the emissions 
limitations required under this paragraph shall be determined pursuant 
to guidelines, promulgated by the Administrator under paragraph (1).'' 
\5\
---------------------------------------------------------------------------

    \5\ 42 U.S.C. 7491(b).
---------------------------------------------------------------------------

    EPA disagrees that the CAA mandates specific control levels (i.e. 
presumptive emission limits) for power plants with a total generating 
capacity of 750 MW or greater. Rather, the CAA directed EPA to develop 
guidelines for States to establish BART emission limits, and required 
that power plants having a total generating capacity in excess of 750 
MW follow the guidelines when establishing BART emission limits. In 
response, in 2005 EPA promulgated the BART Guidelines, which provide a 
detailed description of how a State must approach the BART 
determination process for certain large EGUs, and required that the 
determination of fossil-fuel fired power plants having a total 
generating capacity greater than 750 MW must be made pursuant to the 
BART Guidelines.\6\ As such, the plain reading of the CAA language 
makes it clear the intent was to make the BART Guidelines mandatory for 
EGUs larger than 750 MW, as opposed to presumptive limits. Therefore, 
EPA's proposed rulemaking on the Arkansas RH SIP is not contrary to the 
requirements of the CAA.
---------------------------------------------------------------------------

    \6\ 40 CFR 51.308(e)(1)(ii)(B) and Appendix Y to Part 51.
---------------------------------------------------------------------------

    The EPA went through extensive analysis to establish presumptive 
BART emission limits, and intended these limits to be meaningful. As 
stated in our proposed rulemaking on the Arkansas RH SIP, the purpose 
of the presumptive limits in the BART Guidelines was to identify 
controls that the Agency considered to be generally cost-effective 
across all affected units. Because EPA's extensive analysis found that 
these controls are generally cost-effective across all affected units 
and were anticipated to result in a substantial degree of visibility 
improvement, EPA concluded that such units should at least meet the 
presumptive limits. However, EPA's BART Rule does not state that the 
presumptive limits will represent the ``best available retrofit

[[Page 14609]]

controls'' for all EGUs at these larger power plants. Instead, EPA's 
BART Rule and the BART Guidelines make clear that in developing the 
presumptive emission limits, EPA made many design and technological 
assumptions, and that the presumptive limits may not be BART in every 
case. As such, the presumption in the BART Rule is not that the 
presumptive limits will be BART in every case. Rather, the presumption 
in the BART Rule is more accurately interpreted to be that the controls 
reflected by the presumptive limits are cost-effective and will result 
in considerable visibility improvement. EPA's intent was for these 
generally cost-effective controls to be used in the State's BART 
analysis considering the five factors specified in CAA section 
169A(g)(2), and considering the level of control that is currently 
achievable at the time that the BART analysis is being conducted.
    We note the RHR states:

    ``States, as a general matter, must require owners and operators 
of greater than 750 MW power plants to meet these BART emission 
limits. We are establishing these requirements based on the 
consideration of certain factors discussed below. Although we 
believe that these requirements are extremely likely to be 
appropriate for all greater than 750 MW power plants subject to 
BART, a State may establish different requirements if the State can 
demonstrate that an alternative determination is justified based on 
a consideration of the five statutory factors.'' \7\
---------------------------------------------------------------------------

    \7\ 70 FR 39131.

---------------------------------------------------------------------------
    The RHR also states:

    ``If, upon examination of an individual EGU, a State determines 
that a different emission limit is appropriate based upon its 
analysis of the five factors, then the State may apply a more or 
less stringent limit.'' \8\
---------------------------------------------------------------------------

    \8\ 70 FR 39132.

    Therefore, the presumptive emission limits in the BART Guidelines 
are rebuttable.\9\ The presumptive emission limits apply to power 
plants with a total generating capacity of 750 MW or greater insofar as 
these sources are required to adopt emission limits at least as 
stringent as the presumptive limits, unless after considering the five 
statutory factors, the State determines that the presumptive emission 
limits are not appropriate. Moreover, the RHR and BART Guidelines do 
not exempt states from a five factor BART analysis, and that BART 
analysis may result in a determination of BART emission limits that are 
more or less stringent than the presumptive emission limits for subject 
to BART sources. The RHR states:
---------------------------------------------------------------------------

    \9\ 71 FR 60619.

    ``For each source subject to BART, 40 CFR 51.308(e)(1)(ii)(A) 
requires that States identify the level of control representing BART 
after considering the factors set out in CAA section 169A(g), as 
follows:
States must identify the best system of continuous emission control 
technology for each source subject to BART taking into account the 
technology available, the costs of compliance, the energy and non-
air quality environmental impacts of compliance, any pollution 
control equipment in use at the source, the remaining useful life of 
the source, and the degree of visibility improvement that may be 
expected from available control technology.'' \10\
---------------------------------------------------------------------------

    \10\ 70 FR 39158.

    As previously stated, the presumptive emission limits apply to 
power plants with a total generating capacity of 750 MW or greater 
insofar as these sources are required to adopt emission limits at least 
as stringent as the presumptive limits, unless after considering the 
five statutory factors, the State determines that a more or less 
stringent emission limit is appropriate. Further, EPA is not attempting 
to establish new, more stringent presumptive BART limits. As a matter 
of fact, EPA's proposed rulemaking did not propose to establish 
particular BART emission limits on any of Arkansas's subject to BART 
sources. Instead, EPA's proposed rulemaking proposed to disapprove the 
State's BART limits where the State adopted the NOX and 
SO2 presumptive emission limits without conducting a proper 
five factor BART analysis, as required by the RHR and the CAA, to 
determine if an emission limit more or less stringent than the 
presumptive limits is BART.
    EPA disagrees that our approach is not consistent with the RHR and 
that we must undergo notice and comment rulemaking to follow our 
application of the presumptive BART limits for large coal-fired EGUs. 
EPA reiterates that the RHR and the BART Guidelines make clear that the 
presumptive limits are rebuttable and may not necessarily be the 
appropriate level of control for all EGUs.\11\ Therefore, EPA is not 
required to approve every BART determination that meets the presumptive 
emission limits, especially when there is no analysis that supports the 
state's decision in adopting the presumptive limit instead of a more or 
less stringent emission limit.
---------------------------------------------------------------------------

    \11\ 71 FR 60619.
---------------------------------------------------------------------------

    Comment: The BART Rule shows that an alternative analysis is 
required only when a source cannot meet the presumptive limits (40 CFR 
part 51, appendix Y, section IV.E.5). As such, only when EGUs cannot 
meet presumptive NOX limits using current combustion control 
technology should other technologies be considered. The plain reading 
of the BART Rule is contrary to EPA's proposal to disapprove the 
NOX presumptive emission limits adopted for BART by 
Arkansas.
    Response: Regarding NOX presumptive emission limits, the 
BART Rule provides that:
    ``For coal-fired EGUs greater than 200 MW located at greater than 
750 MW power plants and operating without post-combustion controls 
(i.e. Selective Catalytic Reduction or Selective Non-Catalytic 
Reduction), we have provided presumptive NOX limits, 
differentiated by boiler design and type of coal burned. You may 
determine that an alternative control level is appropriate based on a 
careful consideration of the statutory factors. For coal-fired EGUs 
greater than 200 MW located at power plants 750 MW or less in size and 
operating without post-combustion controls, you should likewise presume 
that these same levels are cost-effective, unless you determine that an 
alternative control level is justified based on consideration of the 
statutory factors.'' \12\
---------------------------------------------------------------------------

    \12\ 70 FR 39171.
---------------------------------------------------------------------------

    The BART Rule does not contain language stating that an alternative 
analysis is required only when a source cannot meet the presumptive 
limits. The BART Guidelines provides the following:
    ``Most EGUs can meet these presumptive NOX limits 
through the use of current combustion control technology, i.e. the 
careful control of combustion air and low-NOX burners. For 
units that cannot meet these limits using such technologies, you should 
consider whether advanced combustion control technologies such as 
rotating opposed fire air should be used to meet these limits.'' \13\
---------------------------------------------------------------------------

    \13\ Appendix Y to Part 51, section IV.E.5.
---------------------------------------------------------------------------

    The intent of this language is to communicate that EPA believes 
that the large majority of units can at least meet the presumptive 
limits at relatively low costs (i.e. without post-combustion controls). 
Because of this, EPA found it appropriate to require EGUs greater than 
200 MW located at greater than 750 MW power plants and without post-
combustion controls to at least meet the presumptive limit, unless 
based on an evaluation of the statutory factors the State found a more 
or less stringent emission limit is appropriate.\14\ The language in 
the BART Guidelines should not be misinterpreted to mean that sources 
capable of meeting the presumptive limits may forego a BART analysis or 
that they need not consider post-combustion controls if they can

[[Page 14610]]

meet the NOX presumptive limits with combustion controls. 
States have a duty to evaluate the five statutory factors,\15\ and 
should consider the level of control that is currently achievable at 
the time the BART analysis is conducted.\16\
---------------------------------------------------------------------------

    \14\ 70 FR 39132.
    \15\ See 40 CFR 51.308(e)(1)(ii)(A) and 42 U.S.C. 7491(g)(2).
    \16\ 70 FR 39171.
---------------------------------------------------------------------------

    Comment: The preamble discussion of the BART Rule shows that the 
presumptive BART limits were intended to establish a presumptively 
acceptable BART determination for large EGUs. The preamble to the 
proposed May 5, 2004, and final July 5, 2005, BART Rule demonstrate the 
clear intent that the presumptive limits in the BART Rule are BART. In 
its proposed disapproval of the Arkansas RH SIP, EPA ignores this. 
Nothing in the BART Rule or the preamble to the rule requires that a 
source achieve a more stringent emission rate if the emission controls 
allow the source to meet the presumptive emission limits. Section 
169A(g) of the CAA requires a balancing of the five statutory factors 
when a State is determining BART. The preamble to the BART Rule 
describes the presumptive limits as reasonable, cost-effective, 
extremely likely to be appropriate and likely to result in a 
significant degree of visibility improvement. The term ``presumptive 
minimum'' or a discussion of controls more stringent than the 
presumptive limits is not found in the BART Rule.
    Response: The EPA disagrees that the presumptive BART limits in the 
BART Rule were intended to establish BART in every case, as nothing on 
the record states that the presumptive limits represent the ``best 
available retrofit controls'' for all EGUs at these large power plants. 
On the contrary, EPA's BART Rule and the BART Guidelines make clear 
that in developing the presumptive emission limits, EPA made many 
design and technological assumptions, and that the presumptive limits 
may not be BART in every case. As such, the presumption in the BART 
Rule is not that the presumptive limits will be BART in every case. 
Rather, the presumption in the BART Rule is more accurately interpreted 
to be that the controls reflected by the presumptive limits are cost-
effective and will result in considerable visibility improvement.
    EPA's proposed rulemaking on the Arkansas RH SIP did not propose to 
require Arkansas's subject to BART sources to achieve an emission rate 
more stringent than the presumptive emission limits. Rather, EPA's 
proposed rulemaking proposed to disapprove the BART emission limits for 
subject to BART sources where the State adopted presumptive emission 
limits without conducting a proper BART five factor analysis. Only 
after the State conducts a proper evaluation of the five statutory 
factors, as required by 40 CFR 51.308(e)(1)(ii)(A) and section 169A(g) 
of the CAA, or EPA conducts one in the context of a FIP, will it be 
demonstrated whether any of Arkansas's subject to BART sources must 
achieve an emission rate more (or less) stringent than the presumptive 
limits.
    EPA agrees that section 169A(g) of the CAA requires a balancing of 
the five statutory factors when a State is determining BART.\17\ EPA is 
also in agreement that the preamble to the BART Rule describes the 
presumptive limits as reasonable, cost-effective, extremely likely to 
be appropriate and likely to result in a significant degree of 
visibility improvement. However, EPA reiterates that the BART Rule does 
not state that the presumptive limits will represent the ``best 
available retrofit controls'' for all EGUs at these larger power 
plants. EPA agrees that the term ``presumptive minimum'' or a 
discussion of controls more stringent than the presumptive limits are 
not explicitly found in the BART Rule, but the BART Rule does require 
that affected sources achieve at least the level of control represented 
by the presumptive limits, unless a proper evaluation of the five 
statutory factors demonstrates that a different level of control is 
BART for the affected sources.
---------------------------------------------------------------------------

    \17\ 42 U.S.C. 7491(g)(2).
---------------------------------------------------------------------------

    Comment: The CAA gives states discretion to make BART 
determinations, and while a state may choose to establish a limit that 
is more stringent than the presumptive limit, there is nothing in the 
BART Rule that would require a state to do so. There are a number of 
examples in the BART regulations and in the preambles to the proposed 
and final BART Rule, showing that a state has discretion to choose to 
demonstrate an alternative control level. The preamble to the BART Rule 
recognizes that in some limited cases, where the source cannot meet the 
presumptive limit, a state could demonstrate an alternative level of 
control. The plain meaning of the BART Rule and the preamble discussion 
of the presumptive limits supports a reading of the BART Rule that 
discretion rests with a state, not EPA, as to whether the presumptive 
limits are reasonable.
    Response: The EPA agrees with the comment that the CAA gives states 
discretion to make BART determinations, and that there are examples in 
the BART regulations and in the preambles to the proposed and final 
BART Rule showing that a state has discretion to choose an alternative 
control level after considering the five statutory factors. However, 
section 169A(g) of the CAA requires States to consider these statutory 
factors in determining BART for affected sources.\18\ If a proper 
evaluation of the five statutory factors demonstrates that an emission 
limit more or less stringent than the presumptive limit is BART for the 
subject to BART source in question, then the State must require the 
source to comply with such emission limit. EPA agrees that states have 
considerable discretion in making BART determinations, but if the State 
has not conducted a proper evaluation of the five statutory factors, as 
required by 40 CFR 51.308(e)(1)(ii)(A) and section 169A(g) of the CAA, 
the State cannot determine that the presumptive limits are the ``best 
available retrofit controls'' for Arkansas's affected sources.
---------------------------------------------------------------------------

    \18\ 42 U.S.C. 7491(g)(2).
---------------------------------------------------------------------------

    Comment: The EPA proposes to reject Arkansas's BART determinations 
that rely on the presumptive BART limits codified in EPA's own BART 
Guidelines, arguing that states are required to perform a case-by-case 
BART analysis in every instance and that they can never rely on the 
presumptive limits (76 FR 64201). The BART rules state that the 
presumptive limits should be adopted unless the state BART-determining 
authority determines that an alternative control level is justified 
based on a consideration of the statutory factors (70 FR 39171). Given 
the assessment EPA undertook to determine the presumptive BART limits 
and that EPA has determined in a formally codified rule that they are 
likely to be suitable as BART limits in nearly every circumstance to 
which they apply- except to the extent states make a determination 
otherwise in a particular case- states properly have discretion to 
adopt the presumptive limits. The determination as to whether the 
presumptive limits should or should not apply is one that is well 
within the discretion of the state. There is little reason for EPA to 
have established the presumptive BART limits if states cannot rely on 
them. If EPA requires a case-by-case analysis for every facility to 
repeatedly test the assumptions underlying the presumptive limits, this 
would result in a senseless approach that would vitiate the 
establishment of the presumptive limits. This would be contrary to 
EPA's own nationally applicable regulations developed as a product of 
notice-and-comment

[[Page 14611]]

rulemaking. If a specific assessment is required in every case, there 
is no reason to have a presumptive limit in the first place. 
Regulations, like statutes, should not be interpreted in a manner that 
is more stringent than the plain language requires. Where there is no 
clear and compelling evidence that presumptive limits cannot be BART 
for a given source, EPA should accept state BART determinations that 
rely on the presumptive limits.
    Response: The EPA agrees that the State has considerable discretion 
in making BART determinations, but if the State has not conducted a 
proper evaluation of the five statutory factors, as required by 40 CFR 
51.308(e)(1)(ii)(A) and section 169A(g) of the CAA, the State cannot 
determine that the presumptive limits are the ``best available retrofit 
controls'' for Arkansas's affected sources. With regard to the comment 
that there is little reason for EPA to have established presumptive 
emission limits if states cannot rely on them, EPA notes that the 
purpose of the presumptive limits in the BART Guidelines was to 
identify controls that the Agency considered to be generally cost-
effective across all affected units. Because EPA's extensive analysis 
found that these controls are generally cost-effective across all 
affected units and were anticipated to result in a substantial degree 
of visibility improvement, EPA concluded that such units should at 
least meet the presumptive limits. Presumptive limits, thus, rather 
than being senseless, provide a starting point for a source specific 
analysis.
    We agree that regulations, like statutes, should not be interpreted 
in a manner that is more stringent than the plain language. However, we 
do not agree that our application of the presumptive limit is more 
stringent than what is required under the CAA and the RHR. Rather, our 
application of the presumptive limit is in keeping with the plain 
language of the CAA and the RHR. Under the RHR, presumptive limits were 
promulgated to provide a path for states to follow when analyzing BART 
for particular EGUs. The BART Rule has presumptive limits that act as a 
starting point for the establishment of BART emission limits unless the 
state's analysis indicates that an emission limit more or less 
stringent than the presumptive limit is required. Please see our 
response to other comments for our discussion of the requirements of 
the CAA visibility program and the RHR.
    EPA disagrees that we should accept state BART determinations that 
rely on the presumptive limits in every case as long as there is no 
clear and compelling evidence that presumptive emission limits cannot 
be BART for a given source. There is no language indicating this in the 
CAA, the RHR, or the BART Guidelines. On the contrary, EPA's BART Rule 
and the BART Guidelines make clear that in developing the presumptive 
emission limits, EPA made many design and technological assumptions, 
and that the presumptive limits may not be BART in every case. EPA's 
intent was for the presumptive limits to be used in the State's BART 
analysis considering the five factors specified in CAA section 
169A(g)(2), and considering the level of control that is currently 
achievable at the time that the BART analysis is being conducted.
    Comment: The intent of the RHR was to gain reasonable progress in 
visibility improvements in Class I areas, with the ultimate goal being 
to achieve background levels of visibility by the year 2064. The BART 
Guidelines developed presumptive BART emission limits that are cost-
effective and capable of meeting reasonable progress. ADEQ followed 
EPA's BART Guidelines in establishing presumptive limits as BART for 
the AEP Flint Creek Boiler No. 1 and Entergy White Bluff Units 1 and 2. 
In its proposed rule, EPA ignores its own guidance to utilize 
presumptive limits and proposes to go beyond the cost-effective 
presumptive limits at Arkansas's EGUs in the near term and to 
essentially perform a BACT analysis for these units, as per EPA's PSD 
regulations. Going beyond the presumptive limits denies the cost-
effectiveness afforded by the presumptive limits and places an 
unnecessary burden on Arkansas electricity ratepayers. EPA's approach 
is beyond what is required to comply with the RHR, as requiring 
standards more stringent than EPA's own presumptive limits is 
unnecessary in order to demonstrate reasonable progress. Implementing 
the presumptive limits as BART meets the intent of the RHR and EPA 
should accept ADEQ's proposed BART requirements for units subject to 
presumptive limits.
    Response: With regard to the comment that the BART Guidelines 
developed presumptive emission limits that are cost-effective and 
capable of meeting reasonable progress, EPA notes that the RHR states 
the following concerning SO2 and NOX presumptive 
limits: ``Based on our analysis of emissions from power plants, we 
believe that applying these highly cost-effective controls at the large 
power plants covered by the guidelines would result in significant 
improvements in visibility and help to ensure reasonable progress 
toward the national visibility goal.'' \19\
---------------------------------------------------------------------------

    \19\ 70 FR 39131.
---------------------------------------------------------------------------

    The comment appears to suggest that a state's adoption of the 
presumptive limits will result in achieving reasonable progress. The 
EPA notes that the RHR stated that applying the highly cost-effective 
controls reflected by the presumptive limits would result in 
significant visibility improvement that would help to ensure reasonable 
progress, not that it would necessarily ensure reasonable progress. 
Furthermore, for a state to achieve reasonable progress during the 
first implementation period, it must also look at point sources beyond 
those that are subject to BART as well as at non-point sources and 
determine, based on consideration of the four statutory factors under 
40 CFR 51.308(d)(1)(i), whether it is reasonable to require these 
sources to install additional pollution controls. Therefore, even if a 
state satisfies the BART requirements, satisfaction of the reasonable 
progress requirements cannot be met by complying with BART requirements 
alone. In addition, the EPA notes that the BART Guidelines make clear 
that the presumptive limits may not be appropriate for all affected 
units.20,21,22
---------------------------------------------------------------------------

    \20\ 70 FR 39131.
    \21\ 70 FR 39132.
    \22\ 71 FR 60619.
---------------------------------------------------------------------------

    The EPA is not ignoring its own guidance to utilize presumptive 
limits, as the BART Rule does not suggest the presumptive limits should 
be viewed as establishing a safe harbor from more stringent regulation 
under the BART provisions. The EPA's proposed rulemaking did not 
propose particular emission limits more stringent than the presumptive 
limits for Arkansas EGUs. Instead, the EPA's proposed rulemaking stated 
that Arkansas must conduct a proper evaluation of the five statutory 
factors, as required by 40 CFR 51.308(e)(1)(ii)(A) and section 169A(g) 
of the CAA, before determining whether the presumptive emission limits 
are the ``best available retrofit controls'' for affected units. 
Therefore, the EPA does not believe that requiring the State to conduct 
a proper evaluation of the five statutory factors places an unnecessary 
burden on Arkansas electricity ratepayers.
    The EPA disagrees with the comment that EPA is requiring Arkansas 
to perform a PSD BACT analysis for affected EGUs. The EPA notes the 
comment is not specific in terms of explaining what aspect of our 
proposed rulemaking led to the belief that EPA is requiring a PSD BACT 
analysis for

[[Page 14612]]

affected EGUs. However, the proposed BART Rule did note that the 
process for a BART analysis is very similar to the BACT review as 
described in the New Source Review Workshop Manual (Draft, October 
1990).\23\ The proposed BART Rule also explained that although very 
similar in process, BART reviews differ in many respects from the BACT 
review. The proposed BART Rule explained these differences as follows:
---------------------------------------------------------------------------

    \23\ 69 FR 25218.
---------------------------------------------------------------------------

    ``First, because all BART reviews apply to existing sources, the 
available controls and the impacts of those controls may differ from 
source to source. Second, the CAA requires you to take slightly 
different factors into account in determining BART and BACT * * * 
Because of the differences in terminology, the BACT review process 
tends to encompass a broader range of factors * * * Finally, for the 
BART analysis, there is no minimum level of control required, while any 
BACT emission limitation must be at least as stringent as any NSPS that 
applies to the source.'' \24\
---------------------------------------------------------------------------

    \24\ 69 FR 25218.
---------------------------------------------------------------------------

    Because of the similarities in the two processes, it is 
understandable that there may be some misunderstanding regarding our 
proposed rulemaking to mean that EPA is requiring subject to BART 
sources to conduct a PSD BACT analysis. Our statement that subject to 
BART sources must consider the ``most stringent option (i.e. maximum 
level of control each technology is capable of achieving) as well a 
reasonable set of options for analysis,'' \25\ may have been 
misinterpreted to mean that we are requiring a PSD BACT analysis. We 
are not requiring a PSD BACT analysis. As explained in our proposed 
rulemaking, the BART Guidelines provide that in identifying all 
options, you must identify the most stringent option (i.e. maximum 
level of control each technology is capable of achieving) as well as a 
reasonable set of options for analysis.\26\ The RHR also provides that 
in establishing source specific BART emission limits, the State should 
identify and consider in the BART analysis the maximum level of 
emission reduction that has been achieved in other recent retrofits at 
existing sources in the source category.\27\ Furthermore, the BART 
Guidelines state that ``[t]echnologies required as BACT or LAER are 
available for BART purposes.'' \28\ The guidelines instruct: ``You are 
expected to identify potentially applicable retrofit control 
technologies that represent the full range of demonstrated 
alternatives. Examples of general information sources are to consider 
include: The EPA's Clean Air Technology center, which includes the 
RACT/BACT/LAER Clearinghouse (RBLC) * * *'' \29\ Our rulemaking is 
consistent with the RHR and the BART Rule, and does not require 
Arkansas's subject to BART sources to conduct a PSD BACT analysis.
---------------------------------------------------------------------------

    \25\ See our proposed rulemaking for the Arkansas RH SIP (76 FR 
64186).
    \26\ See Appendix Y to Part 51.
    \27\ 64 FR 35740.
    \28\ 70 FR 39,164.
    \29\ 70 FR 39,164.
---------------------------------------------------------------------------

    The EPA disagrees with the comment that EPA's approach in our 
proposed rulemaking for the Arkansas RH SIP is beyond what is required 
to comply with the RHR and that requiring standards more stringent than 
EPA's own presumptive limits is unnecessary in order to demonstrate 
reasonable progress. As already explained elsewhere in our response to 
other comments, EPA's rulemaking on the Arkansas RH SIP is not 
requiring Arkansas affected sources to meet standards more stringent 
than the presumptive emission limits. Arkansas must conduct a proper 
evaluation of the five statutory factors, as required by 40 CFR 
51.308(e)(1)(ii)(A) and section 169A(g) of the CAA, before determining 
whether the presumptive emission limits are the ``best available 
retrofit controls'' for affected units. Furthermore, 40 CFR 
51.308(e)(1)(ii)(A) and section 169A(g) of the CAA require that states 
consider the five statutory factors when making BART determinations, 
and the State cannot determine whether or not emission limits more 
stringent than the presumptive emission limits are necessary to 
demonstrate reasonable progress when a proper evaluation of the five 
statutory factors has not been conducted.
    Comment: Appendix Y is very clear that when it comes to presumptive 
BART NOX emissions limits for qualifying EGUs, Arkansas must 
require these EGUs to meet the presumptive BART emissions limits in 
Appendix Y. Not only does Arkansas have broad discretion to apply 
presumptive NOX limits, but Appendix Y actually requires 
this. Arkansas followed this approach in its RH SIP. In its proposed 
rule, EPA now claims that the presumptive limits are something 
completely different than the straightforward directive contained in 
the Code of Federal Regulations, claiming that they are the starting 
point in a BART determination and that sources must ``at least'' meet 
these emission limits. Using the word ``at least'' implies that 
presumptive limits constitute a minimally acceptable degree of control 
that would constitute BART. Nothing in the CAA, RHR, or Appendix Y ever 
states or implies this. EPA also stated in its proposal for the 
Arkansas RH SIP that ``nothing on the record would support the 
conclusion that the presumptive limits represent `best available 
retrofit controls' for all EGUs at these large power plants'' (76 FR 
64201). EPA is attempting to avoid the broad statements it previously 
made regarding the applicability of the ``presumptive BART'' 
NOX emissions limits. EPA's statements in previous 
rulemakings demonstrate that in almost all cases, the presumptive BART 
limits should apply, and the only instance when they should not apply 
is to atypical instances when a source is able to show through a five 
factor test that it is not able to meet the presumptive emission rates, 
even if the expected control technology were installed. EPA's proposal 
for the Arkansas RH SIP also incorrectly claims that in Appendix Y, EPA 
simply concluded that it could not reach a generalized conclusion as to 
the appropriateness of more stringent controls for categories of EGUs 
(76 FR 64201). EPA's failure to recognize the proper role of 
presumptive BART NOX emissions limits is arbitrary and 
capricious because EPA acted in excess of statutory jurisdiction, 
authority, or limitations (North Carolina v. EPA, 531 F.3d 896, 906, DC 
Circuit 2008).
    Response: The EPA disagrees that Appendix Y (i.e. the BART 
Guidelines) makes the presumptive emission limits mandatory for all 
qualifying EGUs. The comment that states have broad discretion to apply 
presumptive NOX limits contradicts the comment that the BART 
Guidelines require states to adopt the presumptive limits. The BART 
Guidelines make clear that the presumptive emission limits are 
rebuttable.\30\ Referring to the NOX presumptive emission 
limits, the BART Rule states that the presumptive emission limits may 
not be appropriate for all sources, as they are ``presumptions only.'' 
\31\ The presumptive emission limits apply to power plants with a total 
generating capacity of 750 MW or greater insofar as these sources are 
required to adopt emission limits at least as stringent as the 
presumptive limits, unless after considering the five statutory 
factors, the State determines that the presumptive emission limits are 
not appropriate. Moreover, the CAA, the RHR, and the BART Guidelines do 
not

[[Page 14613]]

exempt the State from a five factor BART analysis or even provide the 
State with discretion to determine whether or not to conduct an 
analysis of the five statutory factors when the State has adopted the 
presumptive emission limits.
---------------------------------------------------------------------------

    \30\ 71 FR 60619.
    \31\ 70 FR 39134.
---------------------------------------------------------------------------

    We are not claiming that the presumptive emission limits are 
anything else than what is contained in the RHR and the BART 
Guidelines. With regard to the comment that nothing in the CAA, RHR, or 
Appendix Y ever states or implies that the presumptive limits are the 
starting point in a BART determination, EPA notes that there is no 
mention of the presumptive emission limits in the CAA. Further, in 
response to comments on the proposed BART Guidelines that the 
presumptive SO2 EGU limits should be more stringent, EPA 
justified its decision not to establish more stringent SO2 
presumptive limits, by explaining in the preamble to the final BART 
Rule that ``[i]f, upon examination of an individual EGU, a State 
determines that a different emission limit is appropriate based upon 
its analysis of the five factors, then the State may apply a more or 
less stringent limit.'' \32\ Similar statements are made elsewhere in 
the BART Rule. Clearly, the RHR and the BART Rule do not suggest the 
presumptive limits should be viewed as establishing a safe harbor from 
more stringent regulation under the BART provisions. EPA stands by the 
statement made in its proposed rulemaking on the Arkansas RH SIP that 
``nothing on the record would support the conclusion that the 
presumptive limits represent `best available retrofit controls' for all 
EGUs at these power plants.'' \33\ EPA does not find this statement to 
be inconsistent with the RHR and BART Guidelines. As already explained 
above, EPA is clear in the BART Rule and the BART Guidelines that the 
presumptive limits may not be appropriate for every EGU.\34\
---------------------------------------------------------------------------

    \32\ 70 FR 39132.
    \33\ 76 FR 64201.
    \34\ 70 FR 39131, 39132, and 39134.
---------------------------------------------------------------------------

    EPA disagrees with the comment that the only instance when the 
presumptive emission limits should not apply is to atypical instances 
when a source is able to show through a five factor test that it is not 
able to meet the presumptive emission rates. The comment suggests that 
for power plants with a total generating power capacity greater than 
750 MW, the RHR and the BART Rule provide that an evaluation of the 
five statutory factors for these units is merely a vehicle for 
justifying adoption of a BART emission limit less stringent than the 
presumptive limit. This is clearly not the intent of the RH regulations 
and section 169A(g) of the CAA.\35\ As explained above, in response to 
comments on the proposed BART Guidelines that the presumptive 
SO2 EGU limits should be more stringent, EPA justified its 
decision not to establish more stringent presumptive emission limits by 
explaining that after considering the five statutory factors, States 
may find that a more or less stringent emission limit is BART.\36\ 
Similar statements are made elsewhere in the BART Rule. The BART Rule 
states the following:
    ``We recognize that while some scrubber units currently achieve 
reductions greater than 95 percent, not all units can do so. The 
individual units that currently achieve greater than 95 percent control 
efficiencies do not necessarily represent the wide range of unit types 
across the universe of BART-eligible sources * * * In addition, we note 
that the presumption does not limit the States' ability to consider 
whether a different level of control is appropriate in a particular 
case.'' \37\
---------------------------------------------------------------------------

    \35\ See 40 CFR 51.308(e)(1)(ii)(A) and 42 U.S.C. 7491(g)(2).
    \36\ 70 FR 39132.
    \37\ 70 FR 39132.
---------------------------------------------------------------------------

    Further, in the BART Rule, EPA justified its decision not to 
establish presumptive NOX limits based on the use of 
selective catalytic reduction (SCR) for units other than cyclone units, 
stating the following:
    ``For other units, we are not establishing presumptive limits based 
on the installation of SCR. Although States may in specific cases find 
that the use of SCR is appropriate, we have not determined that SCR is 
generally cost-effective for BART across unit types.'' \38\
---------------------------------------------------------------------------

    \38\ 70 FR 39136.
---------------------------------------------------------------------------

    Therefore, EPA stands by its statement in the proposed rulemaking 
on the Arkansas RH SIP that in the BART Guidelines, EPA simply 
concluded that it could not reach a generalized conclusion as to the 
appropriateness of more stringent controls for categories of EGUs.
    The EPA's application of presumptive BART NOX emissions 
limits to Arkansas's RH BART determinations is not arbitrary and 
capricious, because EPA is acting in accordance with the CAA and the 
RHR. The EPA's disapproval of Arkansas's BART determinations that 
adopted the presumptive BART SO2 and NOX emission 
limits without conducting a proper five factor BART analysis is a 
proper exercise of EPA's authority under the Act. Congress crafted the 
CAA to provide for states to take the lead in developing implementation 
plans consistent with the laws and regulations, but balanced that 
decision by requiring EPA to review the plans to determine whether a 
SIP meets the requirements of the CAA. The EPA's review of SIPs is not 
limited to support and cooperation in implementation of a state SIP nor 
is it to simply approve state decisions. When reviewing state SIPs, EPA 
must consider not only whether the state considered the appropriate 
factors in making decisions but acted reasonably in doing so. In 
undertaking such a review, EPA does not usurp the state's authority but 
ensures that such authority is reasonably exercised. EPA has reviewed 
Arkansas's BART determinations for NOX that adopted the 
presumptive limits without conducting a proper five factor BART 
analysis, and we find that Arkansas did not follow the requirements of 
the RHR; that is the basis for our disapproval of those BART 
determinations. For a more detailed explanation of state and EPA 
authority in the development and approval of RH SIPs as well as of how 
EPA's action does not encroach on state authority and is consistent 
with the CAA and the RHR, please see our response to comments under 
section III.F, titled ``Comments on Legal Issues,'' of this final 
rulemaking.
    Comment: The EPA's treatment of presumptive limits in its proposed 
partial disapproval of AR RH SIP is inconsistent with EPA's BART 
Guidelines. EPA departed from the BART Guidelines and made the use of 
presumptive limits meaningless when it disapproved BART determinations 
for Entergy's Lake Catherine Unit 4 and White Bluff Units 1 and 2 that 
adopt the presumptive limits. When EPA departs from the BART 
Guidelines, it is going beyond the scope of the CAA's visibility 
protection program. For certain categories of EGUs, EPA's BART 
Guidelines provide presumptive limits that the states rely upon in 
making BART determinations. The presumptive limit framework outlined in 
the BART Guidelines is intended to function like presumptive evidence 
in litigation where the evidence is received and treated as sufficient 
until it is discredited. Presumptive limits should represent BART until 
and unless they are rebutted. This is not how EPA approached 
presumptive limits in reviewing the Arkansas RH SIP. The BART 
Guidelines provide that if a state wishes to do a case-by-case BART 
then there are presumptive levels of controls for SO2 and 
NOX that can be adopted for certain EGUs that the state 
finds are

[[Page 14614]]

subject to BART. This is what Arkansas did and should be approved by 
EPA.
    Response: The EPA disagrees that the EPA's treatment of the 
presumptive limits in its proposed rulemaking on the Arkansas RH SIP is 
inconsistent with EPA's BART Guidelines and made use of the presumptive 
limits meaningless. EPA notes that Entergy Lake Catherine Unit 4 is 
currently permitted to burn natural gas and fuel oil. EPA's BART 
Guidelines do not establish presumptive emission limits for units that 
burn natural gas and/or fuel oil, therefore the ADEQ did not adopt any 
presumptive limits for Entergy Lake Catherine Unit 4. With regard to 
Entergy White Bluff Units 1 and 2, as stated in our proposed rulemaking 
on the Arkansas RH SIP, the purpose of the presumptive limits in the 
BART Guidelines was to identify controls that the Agency considered to 
be generally cost-effective across all affected units. Because EPA's 
extensive analysis found that these controls are generally cost-
effective across all affected units and were anticipated to result in a 
substantial degree of visibility improvement, EPA concluded that such 
units should at least meet the presumptive limits, unless a more or 
less stringent limit is found to be BART after the state considers the 
five statutory factors. EPA's intent was for these generally cost-
effective controls to be used in the State's BART analysis considering 
the five factors specified in CAA section 169A(g)(2), and considering 
the level of control that is currently achievable at the time that the 
BART analysis is being conducted. Further, 40 CFR 51.308(e)(1)(ii)(A) 
requires that States identify the level of control representing BART 
after considering the five statutory factors set out in CAA section 
169A(g).\39\
---------------------------------------------------------------------------

    \39\ 70 FR 39158.
---------------------------------------------------------------------------

    We disagree that the presumptive limits should represent BART until 
and unless they are rebutted. We reiterate that nothing on the record 
states that the presumptive limits represent the ``best available 
retrofit controls'' for all EGUs at these large power plants. On the 
contrary, EPA's BART Rule and the BART Guidelines make clear that in 
developing the presumptive emission limits, EPA made many design and 
technological assumptions, and that the presumptive limits may not be 
BART in every case.
    While the BART Guidelines provide that there are presumptive levels 
of controls for SO2 and NOX that can be adopted 
for certain EGUs that the state finds are subject to BART, this is true 
only after the state has considered the five statutory factors to 
determine whether a more or less stringent emission limit is BART. In 
the BART Guidelines, EPA noted that the presumptive limits represented 
current control capabilities at the time the BART Rule was promulgated, 
and that we expected that scrubber technology would continue to improve 
and control costs continue to decline.\40\ Therefore, in their 
evaluation of the five statutory factors, states must consider the 
level of control that is currently achievable at the time the BART 
analysis is being conducted.
---------------------------------------------------------------------------

    \40\ 70 FR 39144.
---------------------------------------------------------------------------

    The presumptive limit framework could be compared to the 
presumptive evidence in litigation. However, the comment 
mischaracterizes the role of presumptive evidence in litigation as 
simply to be received and treated as sufficient until it is 
discredited. Presumptive evidence is circumstantial evidence that 
creates belief by showing surrounding circumstances which logically 
lead to a conclusion of fact. At trial, many forms of evidence are 
submitted including circumstantial evidence. All forms of evidence that 
are admitted in court are reviewed and considered before a decision is 
made. While presumptive evidence may meet the sufficiency requirement 
for admission in court, this does not mean that it is looked at alone 
without review of the other admitted evidence. Presumptive evidence 
does not trump other forms of evidence. It is just a type of evidence 
that is reviewed in reaching a court decision. Like presumptive 
evidence, presumptive limits are one line of analysis for reaching a 
decision. Like presumptive evidence in the court room, presumptive 
limits are not the only limit that is looked at when performing the 
five factor BART analysis. Presumptive limits do not preempt states 
from conducting the BART analysis nor do they preclude the evaluation 
of other emission limits to help the state reach its BART 
determination.
    Comment: The EPA should approve the Arkansas RH SIP in its entirety 
and specifically with regards to Arkansas adoption of presumptive 
limits in its BART determinations. Modeling conducted by Arkansas and 
CENRAP demonstrates that Arkansas's adoption of the presumptive limits 
is satisfactory to make reasonable progress toward the national goal by 
2018 and ultimately to achieve the national goal prior to 2064.
    Response: Presumptive emission limits apply to power plants with a 
total generating capacity of 750 MW or greater insofar as these sources 
are required to adopt emission limits at least as stringent as the 
presumptive limits, unless after considering the five statutory 
factors, the State determines that the presumptive emission limits are 
not appropriate. The RHR and the BART Guidelines make clear that the 
presumptive limits will not necessarily be the appropriate level of 
control for all EGUs. Therefore, EPA is not required to approve a 
state's submitted presumptive emission limits in every instance for 
every EGU as BART. For the reasons presented in our proposed 
rulemaking, and as further explained in our response to comments, EPA 
stands by its partial approval and partial disapproval of the BART 
determinations in the Arkansas RH SIP.
    States are required to satisfy all BART requirements in this first 
implementation period regardless of whether modeling demonstrates that 
the state will make reasonable progress by 2018 and meet the national 
goal by 2064. As described in our proposed rulemaking on the Arkansas 
RH SIP, we find that in adopting the SO2 and NOX 
presumptive limits for the AEP Flint Creek Boiler No. 1 and Entergy 
White Bluff Units 1 and 2 without conducting a proper evaluation of the 
five statutory factors, as required by 40 CFR 51.308(e)(1)(ii)(A) and 
section 169A(g) of the CAA, Arkansas did not satisfy all the BART 
requirements for these subject to BART sources. Furthermore, EPA notes 
that the CENRAP modeled the projected visibility conditions anticipated 
at each Class I area in 2018. The CENRAP modeling is based on emissions 
reductions expected to result from Federal, state, and local control 
programs that are either currently in effect or with mandated future-
year emission reduction schedules that predate 2018. The CENRAP 
modeling itself did not show that already mandated controls are 
expected to attain natural visibility conditions by 2064. Rather, the 
rate of visibility improvement anticipated by the CENRAP modeling in 
2018, if sustained, will result in a return to natural visibility prior 
to 2064. The comment that Arkansas is expected to ultimately achieve 
the national goal prior to 2064 assumes that the same level of 
reductions of visibility-impairing pollutants that is expected to occur 
during the first implementation period ending in 2018 will increasingly 
occur during each implementation period until the final implementation 
period ending in 2064. However, there is no guarantee that this will 
occur. The Arkansas RH SIP addresses implementation of the RHR only up 
to the end of the first implementation

[[Page 14615]]

period ending in 2018. Therefore, EPA disagrees that we should approve 
Arkansas's adoption of the presumptive limits on the basis that 
modeling demonstrates that the State's adoption of the presumptive 
limits is satisfactory to make reasonable progress toward the national 
goal by 2018 and ultimately to achieve the national goal prior to 2064.
    Comment: Under the BART Guidelines, presumptive limits were 
established as a default requirement where the presumption would apply 
unless the state has persuasive evidence that an alternative 
determination is justified. According to EPA, the presumptive limits 
reflect highly cost-effective controls that are extremely likely to be 
appropriate for all power plants subject to BART but may be deviated 
from if a state determines that a different emission limit is 
appropriate based upon its analysis of the five factors. 76 FR 39131-
32.
    Response: As reflected in our previous responses to similar 
comments, the proper interpretation of the BART Rule and BART 
Guidelines is that presumptive limits are the ``rebuttable'' starting 
point rather than the ``default requirement'' in making BART 
determinations. Referring to the NOX presumptive emission 
limits, the BART Rule states that the presumptive emission limits may 
not be appropriate for all sources, as they are ``presumptions only.'' 
\41\ EPA notes that presumptive emission limits apply to power plants 
with a total generating capacity of 750 MW or greater insofar as these 
sources are required to adopt emission limits at least as stringent as 
the presumptive limits, unless after considering the five statutory 
factors, the State determines that the presumptive emission limits are 
not appropriate for BART.
---------------------------------------------------------------------------

    \41\ 70 FR 39134.
---------------------------------------------------------------------------

    EPA agrees that the BART Rule and the BART Guidelines provide that 
presumptive limits reflect controls that the Agency considered to be 
generally cost-effective across all affected units. Because EPA's 
extensive analysis found that these controls are generally cost-
effective across all affected units and were anticipated to result in a 
substantial degree of visibility improvement, they may likely be 
appropriate for all Arkansas power plants subject to BART, but Arkansas 
must establish different BART emission limits if an evaluation of the 
five statutory factors reveals that such emission limit is appropriate. 
However, as discussed in our proposed rulemaking, Arkansas did not 
conduct a proper evaluation of the five statutory factors for its 
sources. Therefore, it is not possible to know whether the presumptive 
emission limits or an alternative emission limit is BART for the 
affected sources.
    Comment: The approach in EPA's proposed rule to presumptive limits 
as a starting point is inconsistent with the BART Guidelines. The 
Guidelines do not state that presumptive limits are a starting point 
for a BART determination, but instead establish a presumption in favor 
of the presumptive limits. Presumptive limits serve no purpose if their 
adoption does not presume compliance with the applicable regulations. 
The EPA's inconsistent application of its own guidelines fosters 
regulatory uncertainty among the EGU industry.
    Response: The EPA disagrees that our approach to presumptive limits 
as a starting point in EPA's proposed rule is inconsistent with the 
BART Guidelines and that the presumptive limits serve no purpose if 
their adoption does not presume compliance with the regulations. As 
stated in our proposed rulemaking on the Arkansas RH SIP, the purpose 
of the presumptive limits in the BART Guidelines was to identify 
controls that the Agency considered to be generally cost-effective 
across all affected units. Because EPA's extensive analysis found that 
these controls are generally cost-effective across all affected units 
and were anticipated to result in a substantial degree of visibility 
improvement, EPA concluded that such units should at least meet the 
presumptive limits. EPA's intent was for these generally cost-effective 
controls to be used in the State's BART analysis considering the five 
factors specified in CAA section 169A(g)(2), and considering the level 
of control that is currently achievable at the time that the BART 
analysis is being conducted. The BART Rule makes clear that the 
presumptive emission limits in the BART Guidelines are rebuttable.\42\ 
Referring to the NOX presumptive emission limits, the BART 
Rule states that the presumptive emission limits may not be appropriate 
for all sources, as they are ``presumptions only.'' \43\ Further, in 
response to comments on the proposed BART Guidelines that the 
presumptive SO2 EGU limits should be more stringent, EPA 
explained in the preamble to the final BART Rule that ``[i]f, upon 
examination of an individual EGU, a State determines that a different 
emission limit is appropriate based upon its analysis of the five 
factors, then the State may apply a more or less stringent limit.'' 
\44\ Similar statements are made elsewhere in the BART Rule. It is 
important that, in analyzing the technology, states take into account 
the most stringent emission control level that the technology is 
capable of achieving. States should be sure to consider the level of 
control that is currently achievable at the time that the BART analysis 
is being conducted. Thus, the BART Guidelines require that potential 
emission limits that are more stringent than the presumptive limits 
must be examined as part of the BART determination.
---------------------------------------------------------------------------

    \42\ 71 FR 60619.
    \43\ 70 FR 39134.
    \44\ 70 FR 39132.
---------------------------------------------------------------------------

    Comment: The EPA's proposed disapproval of Arkansas's adoption of 
presumptive limits for some of its BART determinations is inconsistent 
with EPA's acceptance of presumptive limits in other states' BART 
determinations such as Kansas, North Dakota, and Oklahoma. The EPA has 
not identified a rationale or reason for this inconsistency. The lack 
of consistency in its analyses for states' RH SIPs is a cause of 
concern. Applying different standards and/or rendering different 
decisions on similar SIPs when there is no basis for differentiation is 
by definition arbitrary and capricious, and therefore invalid. Instead 
of arbitrarily applying different standards, EPA should use its own 
guidelines to implement the RH program on a consistent, cost-effective 
basis. For Kansas, the EPA approved the Kansas RH SIP including the 
adoption of SO2 and NOX presumptive limits for 
non-oil or gas-fired units similar in design and capacity to Arkansas's 
units. The Kansas RH SIP also included language, which EPA approved, 
that presumptive limits are cost effective in most cases, and if a 
facility proposed controls at or beyond the presumptive limits, it need 
not take into account the remaining statutory factors as BART will be 
met. In addition, the SIP also stated that allowing facilities to use 
presumptive limits to meet BART is within its authority under the RH 
program. This contradicts the EPA's proposed disapproval of the 
Arkansas RH SIP where EPA states that presumptive limits are the 
starting point in a BART determination for these units. For North 
Dakota, EPA proposed to approve the BART determinations that 
SO2 and NOX presumptive limits is BART for 
facilities that are similar in use of fuel and capacity to Arkansas's 
units. For Oklahoma, the EPA has proposed to approve those portions of 
Oklahoma's SIP which adopt the presumptive emissions limits for 
NOX set forth in the Guidelines as BART for the subject

[[Page 14616]]

units. This contradicts EPA's approach for this proposed rule since EPA 
is proposing to disapprove the NOX BART presumptive limit 
for Arkansas's units even though the units are similar in design and 
capacity to the subject units in Oklahoma and Arkansas considered the 
same BART factors as Oklahoma. EPA's simultaneous proposed approval of 
other states' SIPs which use presumptive limits in a manner similar to 
Arkansas and proposed disapproval of those portions of Arkansas's SIP 
demonstrates that EPA is acting inconsistently and has exceeded its 
limited authority in implementation of the visibility protection 
program.
    Response: The EPA disagrees that there is an inconsistency between 
our approach to presumptive limits in our proposed rulemaking on the 
Arkansas RH SIP and that in our proposed rulemaking on the North Dakota 
RH SIP and final rulemakings on the Kansas and Oklahoma RH SIPs. Our 
action on the Arkansas RH SIP is not arbitrary and capricious.
    In the Arkansas RH SIP, the State adopted the NOX and 
SO2 presumptive emission limits for BART without conducting 
any form of BART analysis for AEP Flint Creek Boiler No. 1. For Entergy 
White Bluff Units 1 and 2, the State conducted a five factor BART 
analysis for SO2 and NOX, which we find does not 
appropriately consider all five statutory factors at 40 CFR 
51.308(e)(1)(ii)(B); as such, EPA proposed to disapprove the State's 
determination that the presumptive SO2 and NOX 
emission limits are BART for these two units.\45\ As explained in more 
detail in our proposed rulemaking, the factors that EPA is finding were 
not appropriately considered in the NOX and SO2 
BART analyses for White Bluff Units 1 and 2 are the available control 
technology and the cost and visibility impact of controls beyond the 
presumptive limits. For NOX BART, Arkansas evaluated only 
combustion controls to achieve the NOX presumptive emission 
limit. For SO2 BART, Arkansas evaluated both combustion and 
post-combustion controls, but evaluated the cost and visibility impact 
of operating post-combustion controls (i.e. wet and dry scrubbers) to 
achieve theSO2 presumptive emission limit only. As explained 
in our proposed rulemaking, Arkansas did not evaluate NOX 
and SO2 controls to achieve emission limits beyond the 
presumptive limits, and we believe it is very likely that a proper five 
factor analysis would demonstrate that controls that achieve 
NOX and SO2 emission limits more stringent than 
presumptive limits are cost-effective for White Bluff Units 1 and 2. 
Therefore, we are disapproving the SO2 and NOX 
presumptive emission limits for Flint Creek Boiler No. 1 and White 
Bluff Units 1 and 2 not because the State adopted the presumptive 
emission limits, but rather because the State did not conduct a proper 
evaluation of the five statutory factors when making these BART 
determinations.
---------------------------------------------------------------------------

    \45\ 76 FR 64206.
---------------------------------------------------------------------------

    In contrast, in our evaluation of the Oklahoma RH SIP, EPA found 
that Oklahoma conducted proper BART analyses before determining that 
NOX presumptive limits are BART for some sources. In our 
final rulemaking action on the Oklahoma RH SIP, EPA approved the 
State's NOX BART determinations for Units 1 and 2 at OG&E 
Sooner; Units 4 and 5 at OG&E Muskogee; and Units 3 and 4 at AEP/PSO 
Northeastern. For each of these sources, the State made its 
NOX BART determination based on an evaluation of a number of 
controls, including post-combustion controls operated to achieve an 
emission limit beyond the NOX presumptive limit. Based on an 
evaluation of the five statutory factors, Oklahoma determined that the 
NOX presumptive limit is BART for these sources. In our 
action on the Oklahoma RH SIP, we approved the NOX 
presumptive limits as BART for these sources because Oklahoma's 
NOX BART analyses were appropriate and met the requirements 
of the RHR and CAA.
    In our proposed approval of the Kansas RH SIP, we noted that each 
of Kansas's subject to BART sources are EGUs greater than 200 MW in 
capacity and located at power plants with a total capacity greater than 
750 MW, which are units for which EPA established presumptive BART 
emission limits.\46\ Consistent with our proposed rulemaking on the 
Arkansas RH SIP, in our proposed rulemaking for Kansas, we stated that 
such units must as a general matter at least meet the presumptive 
emission limits as described in the BART Guidelines, unless an 
evaluation of the five statutory factors demonstrated that an 
alternative level of control was appropriate.\47\ The State of Kansas 
performed an evaluation of the five statutory factors for each source 
subject to BART, evaluating the costs and visibility impact of both 
combustion and post-combustion controls.\48\ In fact, the Kansas BART 
evaluation for some units resulted in the adoption of BART emission 
limits more stringent than the NOX and SO2 
presumptive limits.\49\ Based on an evaluation of the five factors, the 
State of Kansas determined, and EPA proposed to approve the 
NOX and SO2 presumptive limits for some units. 
During the public comment period for our proposed approval of the 
Kansas RH SIP, we received comments stating that the Kansas RH SIP was 
incomplete and insufficient because the State did not evaluate the cost 
and visibility improvement resulting from the most stringent emission 
limit capable of being achieved by the various SO2 and 
NOX controls considered for these units. Subsequently, the 
State provided EPA information on the cost and visibility impact of 
operating the various NOX and SO2 control 
technologies considered by the State at an emission rate more stringent 
than the presumptive limits. The information provided by the State 
demonstrated that operation of these controls to achieve an emission 
limit more stringent than the presumptive limit would result in high 
costs and very low visibility improvement, and thereby not be cost-
effective. Based upon its evaluation of the State's five factor 
supplemented analysis, EPA agreed with Kansas that it is reasonable to 
determine that the cost of further control beyond presumptive limits is 
not warranted and finalized its proposed approval of the Kansas RH SIP 
without changes.\50\ In particular, for the Westar Jeffrey Units 1 and 
2, EPA agreed with the State of Kansas that given the very low 
visibility improvement modeled for the additional SO2 
control (i.e. operating a scrubber at a control efficiency that would 
achieve an emission rate of 0.05 lb/MMBtu instead of the presumptive 
emission rate of 0.15 lb/MMBtu), it is not reasonable to establish an 
SO2 emission limit more stringent than the presumptive 
limit. Arkansas has not provided EPA with information demonstrating 
that operation of SO2 and NOX controls to achieve 
an emission limit more stringent than the presumptive limits is not 
cost-effective for Flint Creek Boiler No. 1 and White Bluff Units 1 and 
2. Since controls capable of achieving a more stringent emission limit 
than the NOX and SO2 presumptive limits have been 
found to be technically feasible and cost-effective at similar sources, 
the State must evaluate these controls in its BART analysis. Therefore, 
EPA's final approval of the NOX and SO2 
presumptive limits for some EGUs in Kansas is not inconsistent with our 
proposed disapproval of the NOX and

[[Page 14617]]

SO2 presumptive limits for White Bluff Units 1 and 2 and 
Flint Creek Boiler No. 1. With regard to the comment that the Kansas RH 
SIP included language that that if a subject facility proposes controls 
at or beyond the presumptive limits then BART will be met and that 
allowing facilities to use presumptive limits to meet BART is within 
the State's authority under the RH program, EPA notes that although the 
Kansas RH SIP did include such language, EPA did not approve or propose 
to approve the BART determinations by Kansas based on such reasoning. 
EPA notes that Kansas supplemented its BART evaluation by providing 
additional information on the costs and visibility impacts associated 
with various NOX and SO2 control technologies. 
This additional information constituted an important part of the basis 
for EPA's approval of the Kansas RH SIP. As a general matter, in 
evaluating a SIP submittal, EPA considers the state's rationale for its 
determinations but reaches a decision as to whether a SIP meets the 
relevant statutory and regulatory requirements based on consideration 
of other factors as well. EPA's approval of a SIP does not mean that 
EPA has determined that every statement or analysis provided by the 
state was appropriate or reasonable or that EPA agrees with the state's 
interpretation of the relevant legal requirements. Furthermore, the 
preamble to our proposed rulemaking on the Kansas RH SIP states that as 
presumptive units, each of Kansas' five subject to BART units ``must as 
a general matter at least meet the presumptive emission limits as 
described in the BART Guidelines.'' \51\ This is consistent with 
statements made in the preamble to our proposed rulemaking on the 
Arkansas RH SIP. EPA believes that our approach to presumptive limits 
in our final action on the Kansas RH SIP is consistent with that in our 
action on the Arkansas RH SIP.
---------------------------------------------------------------------------

    \46\ 76 FR 52616.
    \47\ 76 FR 52616.
    \48\ 76 FR 52617.
    \49\ 76 FR 80754.
    \50\ 76 FR 80754.
    \51\ 76 FR 52604, at 52616.
---------------------------------------------------------------------------

    While the SO2 controls evaluated by North Dakota for the 
Great River Energy Coal Creek Station Units 1 and 2 are not expected to 
achieve an emission limit more stringent than the SO2 
presumptive emission limit, EPA disagrees that our approach to 
presumptive limits in our proposed action on North Dakota's BART 
determinations for the Coal Creek Station Units 1 and 2 is inconsistent 
with that in our proposed action on Arkansas's BART determinations for 
Flint Creek Boiler 1 and White Bluff Units 1 and 2. First of all, the 
SO2 presumptive limits do not apply to North Dakota's Coal 
Creek Station Units 1 and 2, as the presumptive limits do not apply to 
coal-fired units with existing SO2 post-combustion 
controls.\52\ The Coal Creek Station Units 1 and 2 have existing wet 
scrubbers, and as such, the cost effectiveness (on a dollar/tons 
reduced basis) of additional controls and/or upgrades to the existing 
scrubbers may not be as cost-effective as the installation and 
operation of a new scrubber would be at a unit with no existing post-
combustion controls (as is the case with Arkansas's Flint Creek Boiler 
No. 1 and White Bluff Units 1 and 2). In addition, we note that the 
Coal Creek Station Units 1 and 2 burn pulverized lignite coal, while 
Flint Creek Boiler No. 1 burns low sulfur western coal (i.e. sub-
bituminous coal) and White Bluff Units 1 and 2 burn sub-bituminous and 
bituminous coal. Lignite coal generally has higher sulfur content than 
sub-bituminous and bituminous coal, and therefore, its combustion 
produces a greater amount of SO2 emissions. As such, the 
operation of a given control technology, in this case a wet scrubber, 
at a lignite firing unit (such as North Dakota's Coal Creek Station 
Units 1 and 2) may not necessarily achieve an emission limit as 
stringent as that capable of being achieved at a unit burning sub-
bituminous and/or bituminous coal (such as Arkansas's Flint Creek 
Boiler No. 1 and White Bluff Units 1 and 2). In light of the above, we 
believe that our approach to presumptive limits in our proposed action 
on the North Dakota RH SIP is not inconsistent with that in our 
proposed action on the Arkansas RH SIP.
---------------------------------------------------------------------------

    \52\ The BART Guidelines provide that States must require 750 MW 
power plants to meet specific control levels for SO2 of 
either 95% control or 0.15 lb/MMBtu, for each EGU greater than 200 
MW that is currently uncontrolled unless you determine that an 
alternative control level is justified based on a careful 
consideration of the statutory factors (Appendix Y to Part 51, 
section IV.E.4.).
---------------------------------------------------------------------------

    As articulated in our proposed rulemaking on the North Dakota RH 
SIP, the Great River Energy Stanton Unit 1 is located at a 188 MW power 
plant. Therefore, presumptive NOX and SO2 
emission limits do not apply to Stanton Unit 1. As shown in Tables 7 
and 8 of our proposed rulemaking on the North Dakota RH SIP, in its 
five factor analyses for SO2 for this unit (for both the 
lignite and the Powder River Basin coal firing scenarios), North Dakota 
considered a number of post-combustion control options, several of 
which were expected to achieve an emission limit more stringent than 
the SO2 presumptive limit, including one of which would 
achieve 95% control efficiency.\53\ Based on its consideration of the 
five statutory factors, North Dakota determined that an SO2 
emission limit of 0.24 lb/MMBtu for lignite burning and an emission 
limit of 0.16 lb/MMBtu for Powder River Basin coal burning is BART for 
SO2. For NOX for Stanton Unit 1, North Dakota 
evaluated both combustion and post-combustion controls for both the 
lignite and Powder River Basin Coal burning scenarios. In its 
evaluation of controls, North Dakota considered the operation of 
selective non-catalytic reduction (SNCR) to achieve a control 
efficiency of 90% for lignite burning and 88% for Powder River Basin 
coal burning, which corresponds to an emission limit beyond the 
NOX presumptive limit. Based on its consideration of the 
five statutory factors, North Dakota determined that a NOX 
emission limit of 0.29 lb/MMBtu for lignite burning and 0.23 lb/MMBtu 
for Powder River Basin coal burning is BART for NOX. In our 
proposal, we did not identify any flaws with North Dakota's BART 
analyses for NOX and SO2 for this unit, and 
proposed to approve North Dakota's BART determinations. EPA's approach 
to presumptive limits in our proposed action on North Dakota's BART 
determinations for the Great River Energy Stanton Unit 1is not 
inconsistent with that in our proposed action on the Arkansas BART 
determinations for White Bluff Unit 1 and 2 and Flint Creek Boiler No. 
1 because North Dakota considered controls beyond the NOX 
and SO2 presumptive emission limits. This was not done by 
Arkansas in the NOX and SO2 BART analyses for 
White Bluff Units 1 and 2 and Flint Creek Boiler No. 1. Furthermore, 
presumptive NOX and SO2 emission limits do not 
apply to Stanton Unit 1.
---------------------------------------------------------------------------

    \53\ 76 FR 58570, at 58586 and 58587.
---------------------------------------------------------------------------

    North Dakota's Minnkota Power Cooperative Milton R. Young Station 
Unit 1 has no existing SO2 post-combustion controls, while 
Unit 2 has an existing wet scrubber for control of SO2. As 
such, the SO2 presumptive limits don't apply to Unit 2. As 
shown in Table 12 of our proposed rulemaking on the North Dakota RH 
SIP, for Milton R. Young Station Unit 1, North Dakota considered post 
combustion controls that were expected to achieve 95% control 
efficiency, which corresponds to an emission limit more stringent than 
the SO2 presumptive limit.\54\ As shown in Table 13 of our 
proposed rulemaking on the North Dakota RH SIP, for Milton R. Young 
Station Unit 2 North Dakota considered upgrades to the existing wet 
scrubber that were expected to achieve

[[Page 14618]]

95% control efficiency, which corresponds to an emission limit beyond 
the SO2 presumptive limit.\55\ In our proposed rulemaking on 
the North Dakota RH SIP, we did not identify any flaws with North 
Dakota's SO2 BART analysis for these units. In light of the 
fact that SO2 presumptive limits don't apply to Milton R. 
Young Station Unit 2 and that North Dakota evaluated controls to 
achieve 95% control efficiency for both Units 1 and 2, which 
corresponds to an emission limit more stringent than the SO2 
presumptive limit, we believe that EPA's approach to presumptive limits 
in our proposed action on North Dakota's BART determinations for 
Minnkota Power Cooperative Milton R. Young Station Unit 1 and 2 is not 
in conflict with that in our proposed action on Arkansas's BART 
determinations for White Bluff Units 1 and 2 and Flint Creek Boiler No. 
1.
---------------------------------------------------------------------------

    \54\ 76 FR 58570, at 58589.
    \55\ 76 FR 58570, at 58590.
---------------------------------------------------------------------------

    While the SO2 controls evaluated by North Dakota for the 
Basin Electric Power Cooperative Leland Olds Station Units 1 and 2, 
which are located at a 656 MW coal fired power plant, are not expected 
to achieve an emission limit more stringent than the SO2 
presumptive emission limit, EPA disagrees that our approach to 
presumptive limits in our proposed action on North Dakota's BART 
determinations for the Leland Olds Station Unit 1 and 2 is inconsistent 
with that in our proposed action on Arkansas's BART determinations for 
Flint Creek Boiler No. 1 and White Bluff Units 1 and 2. As with the 
Great River Energy Stanton Unit 1, the SO2 and 
NOX presumptive limits do not apply to North Dakota's Leland 
Olds Station Units 1 and 2, as the presumptive limits do not apply to 
coal fired power plants with a total generating capacity less than 750 
MW.\56\ As shown in Table 17 of our proposed rulemaking on the North 
Dakota RH SIP, for Leland Olds Station Unit 1 North Dakota considered 
both NOX combustion and post-combustion controls capable of 
achieving 80% control efficiency, which corresponds to an emission 
limit much more stringent than the NOX presumptive 
limit.\57\ In our proposed rulemaking on the North Dakota RH SIP, we 
did not identify any flaws with North Dakota's BART analysis for 
NOX for Unit 1 and proposed to approve North Dakota's 
determination that BART for NOX is 0.19 lb/MMBtu for Leland 
Olds Station Unit 1. EPA's approach to presumptive limits in our 
proposed action on North Dakota's BART determination for NOX 
for the Leland Olds Station Unit 1 is not inconsistent with that in our 
proposed action on Arkansas's BART determinations for Flint Creek 
Boiler No. 1 and White Bluff Units 1 and 2 because in its evaluation of 
controls for NOX for Unit 1 (for which we did not propose to 
find any flaws), North Dakota considered controls beyond the 
NOX presumptive emission limits. This was not done by 
Arkansas in the NOX and SO2 BART analyses for 
White Bluff Units 1 and 2 and Flint Creek Boiler No. 1. Furthermore, 
the NOX and SO2 presumptive limits do not apply 
at the Leland Olds Station Units 1 and 2.
---------------------------------------------------------------------------

    \56\ The BART Guidelines provide that States must require 750 MW 
power plants to meet specific control levels for SO2 of 
either 95% control or 0.15 lb/MMBtu, for each EGU greater than 200 
MW that is currently uncontrolled unless you determine that an 
alternative control level is justified based on a careful 
consideration of the statutory factors (Appendix Y to Part 51, 
section IV.E.4.).
    \57\ 76 FR 58570, at 58593.
---------------------------------------------------------------------------

    In summary, EPA disagrees that there is an inconsistency between 
our approach to presumptive limits in our proposed rulemaking on the 
Arkansas RH SIP and that in our proposed rulemaking on the North Dakota 
RH SIP and final rulemakings on the Kansas and Oklahoma RH SIPs.
    Comment: The process used by the State of Arkansas in adopting the 
presumptive emission limits set forth in EPA's BART Guidelines as BART 
for Entergy White Bluff was improper. The record reflects that neither 
ADEQ nor the APCEC conducted its analysis of the statutory factors 
required to establish BART, but merely adopted EPA's presumptive limits 
as proposed by the owners and operators of the Entergy White Bluff 
Units 1 and 2. The record does not reflect that any analysis was done 
by ADEQ to determine if the estimated operating cost and the projected 
cost per deciview (dv) improvement for wet scrubbing control technology 
for the White Bluff plant were realistic, whether those costs were 
consistent with the cost assumptions underlying EPA's development of 
presumptive limits in the BART Guidelines, or whether other options 
were available to address RH concerns or whether existing control 
technology at White Bluff was sufficient. Moreover, after Arkansas's RH 
SIP was adopted by the APCEC, Entergy submitted a revised 2008 BART 
analysis to ADEQ that reflected a more than 300% increase in the costs 
of compliance for the White Bluff facility. After this, Entergy filed 
with the Arkansas Public Service Commission a claim that the RHR 
compliance costs for White Bluff would exceed $1 billion. Nothing in 
the record indicates that Arkansas considered these increased costs in 
establishing BART emission limits for Entergy White Bluff in the 
Arkansas RH SIP. In addition, EPA was not aware or did not consider 
Entergy's 2008 revised BART analysis for White Bluff.
    Response: The EPA agrees that the Arkansas BART determination for 
Entergy White Bluff Units 1 and 2 was flawed. As described in our 
proposed rulemaking, the State failed to adequately consider controls 
and BART emission limits beyond the presumptive limits and the State 
did not determine that the general assumptions underlying the EPA's 
analysis of presumptive limits in its 2005 BART Rule were not 
applicable to White Bluff. As to the revised 2008 BART analysis for 
White Bluff, which the source submitted to ADEQ, EPA notes that the 
Arkansas RH SIP submittal that EPA received from the State on September 
23, 2008, contains a BART analysis for White Bluff dated December 
2006.\58\ The Arkansas RH SIP submittal does not contain the revised 
2008 BART analysis for White Bluff, nor was the revised 2008 BART 
analysis for White Bluff ever submitted to EPA by the State as an 
official RH SIP revision. Given this, EPA has not taken the revised 
analysis into account in evaluating the Arkansas RH SIP.
---------------------------------------------------------------------------

    \58\ See ``BART Analysis for the White Bluff Steam Electric 
Station,'' dated December 2006 and prepared by Robert Paine, found 
in Appendix 9.3A of the Arkansas RH SIP.
---------------------------------------------------------------------------

    Comment: The process used by the State of Arkansas in adopting the 
presumptive emission limits set forth in EPA's Guidelines as BART for 
Flint Creek Boiler No. 1 was improper. For the Flint Creek facility, 
there is no BART analysis or other information that indicates the 
actual costs of various control technologies or other options for 
addressing RH concerns, and there is nothing in the record that 
reflects that ADEQ considered the actual costs of controls at the Flint 
Creek plant in its determination of BART for this facility. This is due 
to Arkansas's improper adoption and reliance on EPA's presumptive 
limits.
    Response: The EPA agrees that the process used by Arkansas in 
adopting the NOX and SO2 presumptive emission 
limits set forth in EPA's Guidelines for BART for Flint Creek Boiler 
No. 1 was improper. The State did not consider the costs of controls or 
any of the other statutory factors, as required under the RHR and the 
Act, when making its BART determinations for this source. For this 
reason we are finalizing our proposed disapproval of the States' 
NOX

[[Page 14619]]

and SO2 BART determinations for Flint Creek Boiler No. 1.
    Comment: The EPA approval of the PM BART determination for Flint 
Creek Boiler No. 1 in which BART analysis was not conducted because 
visibility impacts are minimal contradicts EPA's later rejection of 
presumptive limits for failure to conduct a full BART analysis for 
NOX and SO2 at the same facility.
    Response: Our proposed approval of the PM BART determination for 
the AEP Flint Creek Boiler No. 1 does not contradict our proposed 
disapproval of the NOX and SO2 presumptive limits 
for the same source. In our review of the Arkansas RH SIP, we evaluated 
the determination by ADEQ that no additional PM controls are required 
at the Flint Creek Boiler No. 1. ADEQ's determination was based on the 
pre-control modeling performed by ADEQ and a review of AEP SWEPCO's 
statement that the PM visibility modeling did not ``trip the BART 
impact threshold.'' We reviewed the pre-control modeling preformed by 
ADEQ using the 24-hr actual maximum emissions from the baseline period. 
The modeling results in Appendix 9.2B of the Arkansas RH SIP and 
presented in Table 7-6 of Appendix A of the Technical Support Document 
(TSD),\59\ indicate that PM contributes less than 0.5% of the total 
visibility impacts from Flint Creek Boiler No. 1 at all nearby Class I 
areas with the exception of Upper Buffalo. PM contributions to 
visibility impacts at Upper Buffalo from Flint Creek are less than 2% 
of the total visibility impairment at this Class I area. On the most 
impacted day at Upper Buffalo, modeling the 24-hr actual maximum 
emissions demonstrates that PM contributes only 0.07 dv of the total 
3.781 dv modeled visibility impact from the source. As stated in the 
proposal, we found that the visibility impact from PM emissions alone 
is so minimal such that the installation of any additional PM controls 
on the unit (including any upgrades to the existing controls) could 
only have minimal visibility benefit and therefore would not be 
justified. This is in keeping with the BART Rule, which states the 
following:
---------------------------------------------------------------------------

    \59\ These documents can be found in the docket for our 
rulemaking.

    ``Consistent with the CAA and the implementing regulations, 
States can adopt a more streamlined approach to making BART 
determinations where appropriate. Although BART determinations are 
based on the totality of circumstances in a given situation, such as 
the distance of the source from a Class I area, the type and amount 
of pollutant at issue, and the availability and cost of controls, it 
is clear that in some situations, one or more factors will clearly 
suggest an outcome. Thus, for example, a State need not undertake an 
exhaustive analysis of a source's impact on visibility resulting 
from relatively minor emissions of a pollutant where it is clear 
that controls would be costly and any improvements in visibility 
resulting from reductions in emissions of that pollutant would be 
negligible. In a scenario, for example, where a source emits 
thousands of tons of SO2 but less than one hundred tons 
of NOX, the State could easily conclude that requiring 
expensive controls to reduce NOX would not be 
appropriate. In another situation, however, inexpensive 
NOX controls might be available and a State might 
reasonably conclude that NOX controls were justified as a 
means to improve visibility despite the fact that the source emits 
less than one hundred tons of the pollutant.'' \60\
---------------------------------------------------------------------------

    \60\ 70 FR 39116.

    Clearly, the most effective controls to address visibility 
impairment from the source are those that would reduce emissions of 
visibility impairing pollutants other than direct emissions of PM. 
Therefore, we are finalizing our proposed disapproval of the 
NOX and SO2 BART determinations for Flint Creek 
Boiler No. 1, as ADEQ did not properly identify and evaluate 
NOX and SO2 controls to address visibility 
impairment from the source. As explained elsewhere in our response to 
comments, this is consistent with the BART Guidelines and with our 
action on other state's RH SIPs.
    Comment: The EPA's 2004 proposed RHR provided extensive technical 
justification to establish that the presumptive limits represent cost 
effective technologies equivalent to BART. In addition, the 2004 
proposed RHR provides that the adoption of the presumptive limits by 
the state is acceptable unless the states choose to conduct a BART 
analysis to support different limits. Arkansas relied on the 2004 
proposed RHR to adopt presumptive limits, along with consultation with 
BART-eligible sources to determine whether any site-specific factors 
vary significantly from those examined by EPA. Since no factors have 
been identified by the affected sources, Arkansas adopted EPA's 
presumptive limit without any further analysis. That is all that is 
required under the RHR.
    Response: The EPA agrees that we went through extensive analysis to 
provide presumptive BART emission limits. As stated in our proposed 
rulemaking on the Arkansas RH SIP, the purpose of the presumptive 
limits in the BART Guidelines was to identify controls that the Agency 
considered to be generally cost-effective across all affected units. 
Because EPA's extensive analysis found that these controls are 
generally cost-effective across all affected units and were anticipated 
to result in a substantial degree of visibility improvement, EPA 
concluded that such units should at least meet the presumptive limits. 
However, the RHR and the BART Guidelines make clear that the 
presumptive limits are rebuttable.\61\ As discussed elsewhere in our 
response to comments, the RHR and the BART Guidelines make clear that 
the presumptive limits will not necessarily be the appropriate level of 
control for all EGUs. Therefore, EPA cannot approve any BART 
determination that relies upon the presumptive emission limit unless 
the five factor BART analysis shows the presumptive emission limit 
meets BART. EPA disagrees that the 2004 proposed RHR provides that the 
adoption of the presumptive limits by the state is acceptable unless 
the state chooses to conduct a BART analysis to support different 
limits. The RHR (in some instances referred to in the comment as the 
BART Rule) and the BART Guidelines do not provide that a state may 
choose to conduct a BART analysis to support different limits. The RHR 
states the following concerning presumptive limits:
---------------------------------------------------------------------------

    \61\ 71 FR 60619.
---------------------------------------------------------------------------

    ``If, upon examination of an individual EGU, a State determines 
that a different emission limit is appropriate based upon its analysis 
of the five factors, then the State may apply a more or less stringent 
limit.'' \62\
---------------------------------------------------------------------------

    \62\ 70 FR 39132.
---------------------------------------------------------------------------

    There is similar language elsewhere in the RHR and the BART 
Guidelines. The RHR and the BART Guidelines do not contain language 
giving the State discretion to determine whether or not to conduct a 
five factor BART analysis when the presumptive emission limits have 
been adopted.
    The EPA disagrees that reliance on the 2004 proposed RHR to adopt 
presumptive limits along with consultation with subject to BART sources 
to determine whether any site-specific factors vary significantly from 
those examined by EPA is all Arkansas is required to do to satisfy the 
BART requirements under the RHR. The RHR states that for each source 
subject to BART, states are required to identify BART after considering 
the five statutory factors in CAA section 169A(g), as follows:

    ``States must identify the best system of continuous emission 
control technology for each source subject to BART taking into 
account the technology available, the costs of compliance, the 
energy and non-air quality environmental impacts of compliance, any 
pollution control equipment in use at the

[[Page 14620]]

source, the remaining useful life of the source, and the degree of 
visibility improvement that may be expected from available control 
technology.'' \63\
---------------------------------------------------------------------------

    \63\ 70 FR 39158.

    Therefore, adoption of the NOX and SO2 
presumptive limits alone does not satisfy the requirements of the RHR 
and the CAA.
    Comment: The EPA's 2004 proposed RHR supports the position that the 
presumptive limits identified in the RHR are adequate to meet the 
visibility requirements for the first implementation period of the RHR. 
Thus, Arkansas's use of presumptive limits should be approved because, 
like the RHR confirms, use of presumptive limits by Arkansas ensures 
that there is sufficient visibility improvement to satisfy the URP 
goals. The EPA's suggestion that a more detailed or extensive 
investigation is required is not supported by the RHR or guidance. It 
is the state's prerogative to make this determination and to choose 
what sources of information and degree of investigation is adequate. 
Having confirmed EPA's expectations, the state's submission should be 
approved.
    Response: Neither the 2004 proposed nor the final RHR provide that 
adoption of the presumptive emission limits identified in the RHR are 
all that is necessary to meet the visibility requirements for the first 
implementation period of the RHR. The EPA disagrees that the RHR 
confirms that use of presumptive limits by states ensures that there is 
sufficient visibility improvement to satisfy the URP goals. It appears 
that the comment may have been referring to the ``national visibility 
goal,'' or ``reasonable progress goals,'' (which are interim visibility 
goals towards meeting the national visibility goal), instead of the 
``URP goals.'' The RHR states the following regarding the 
SO2 and NOX presumptive limits:
    ``Based on our analysis of emissions from power plants, we believe 
that applying these highly cost-effective controls at the large power 
plants covered by the guidelines would result in significant 
improvements in visibility and help to ensure reasonable progress 
toward the national visibility goal.'' \64\
---------------------------------------------------------------------------

    \64\ 70 FR 39131.
---------------------------------------------------------------------------

    A full reading of the RHR and the BART Rule, demonstrates that the 
proper interpretation of this statement is that because EPA found these 
controls to be generally highly cost-effective and would result in 
significant visibility improvement, EPA concluded that requiring 
affected sources to achieve at least this level of control would help 
ensure reasonable progress toward the national visibility goal. The RHR 
did not confirm that by adopting the presumptive emission limits states 
would ensure sufficient visibility improvement to satisfy their 
reasonable progress goals, since for the first implementation period 
this can only be confirmed by EPA's full approval of the state's RH 
SIP. Furthermore, for a state to achieve reasonable progress during the 
first implementation period, it must look at sources beyond those that 
are subject to BART as well as at non-point sources and determine, 
based on consideration of the four statutory factors at 40 CFR 
51.308(d)(1)(i), whether it is reasonable to require these sources to 
install additional pollution controls. Therefore, even if states 
satisfy the BART requirements, satisfaction of the reasonable progress 
requirements can't be met by complying with BART requirements alone.
    With regard to the comment that the RHR and BART Guidelines do not 
support EPA's position that a more detailed or extensive investigation 
is required, EPA notes that in response to comments on the proposed 
BART Guidelines that the presumptive SO2 EGU limits should 
be more stringent, EPA justified its decision not to establish more 
stringent presumptive emission limits in the preamble to the final BART 
Rule by explaining that ``[i]f, upon examination of an individual EGU, 
a State determines that a different emission limit is appropriate based 
upon its analysis of the five factors, then the State may apply a more 
or less stringent limit.'' \65\ Similar statements are made elsewhere 
in the BART Rule. Clearly, the RHR and the BART Rule do not suggest the 
presumptive limits should be viewed as establishing a safe harbor from 
more stringent regulation under the BART provisions. While states do 
have discretion in how to go about making BART determinations, states 
have a duty to evaluate the five statutory factors,\66\ and should 
consider the level of control that is currently achievable at the time 
the BART analysis is conducted.\67\
---------------------------------------------------------------------------

    \65\ 70 FR 39132.
    \66\ See 40 CFR 51.308(e)(1)(ii)(A) and 42 U.S.C. 7491(g)(2).
    \67\ 70 FR 39171.
---------------------------------------------------------------------------

    Comment: The EPA was incorrect in disapproving ADEQ's 
SO2 and NOX BART determinations that adopted the 
presumptive limit for subject to BART power plants greater than 750 MW. 
ADEQ used the presumptive limits provided by EPA in the BART Rule and 
worked with the affected facilities to make BART determinations.
    Response: The EPA disagrees. States have a duty to evaluate the 
five statutory factors,\68\ and should consider the level of control 
that is currently achievable at the time the BART analysis is 
conducted.\69\ As already explained in our response to similar comments 
in this final rulemaking, adoption of the presumptive emission limits 
for subject to BART EGUs greater than 750 MW, without a proper 
evaluation of the five statutory factors, is not sufficient to meet the 
BART requirements in the RHR and the BART Rule.
---------------------------------------------------------------------------

    \68\ See 40 CFR 51.308(e)(1)(ii)(A) and 42 U.S.C. 7491(g)(2).
    \69\ 70 FR 39171.
---------------------------------------------------------------------------

    Comment: The EPA incorrectly states that such BART-eligible sources 
should at least meet the presumptive limits. BART-eligible sources are 
just that--eligible. As such, these sources are not required to meet 
any limit until modeling indicates that the unit either causes or 
contributes to visibility impairment. The use of the phrase ``BART-
eligible'' in this context appears to be a mistaken reference to 
``subject-to-BART'' sources.
    Response: The EPA agrees that we meant to say that ``subject to 
BART sources'' rather than ``BART eligible sources'' should at least 
meet the presumptive limits. This misstatement is minor and did not 
affect our evaluation of Arkansas's RH SIP.

B. Comments on Reasonable Progress Goals and Long Term Strategy

    Comment: The EPA's proposed rule would disapprove Arkansas's RPGs 
because in EPA's view the State did not provide an analysis that 
considered the four statutory factors under 40 CFR 51.308(d)(1)(i)(A) 
to evaluate the potential of controlling certain sources or source 
categories for addressing visibility impacts from man-made sources. 
Whether or not this is true, it does not appear that the state has 
fallen short of its obligations under the RHR and applicable EPA 
guidance. States generally must consider the reasonable progress 
factors and the URP in establishing RPGs. Arkansas clearly considered 
the URP and has demonstrated that the measures included in the SIP 
exceed those necessary to meet the URP for both of its Class I areas. 
As for the reasonable progress factors, the BART Guidelines note their 
substantial similarity to the BART factors (70 FR 39143), and EPA 
guidance makes clear that states need not reassess the reasonable 
progress factors for sources subject to BART for which the state has 
already completed a BART analysis. As such, EPA has not

[[Page 14621]]

identified a flaw in the state's reasonable progress analysis 
warranting disapproval of Arkansas's selected RPGs. EPA must respect 
the states' considerable discretion in determining RPGs and cannot 
substitute its judgment for that of the state simply because EPA would 
have performed a different type of assessment if it had the authority 
to establish RPGs. The EPA does not have the authority to require the 
adoption of RPGs other than those found by the states to be reasonable 
and must defer to the state's reasonable progress determinations.
    Response: The EPA disagrees that the Arkansas RH SIP has not fallen 
short of its obligations under the RHR and applicable EPA guidance. 
With respect to the RPG requirements, the State has fallen short of its 
obligations precisely because it did not provide an analysis that 
considered the four statutory factors, as required under 40 CFR 
51.308(d)(1)(i)(A). The RHR states the following with regard to RPG 
requirements:

    ``Today's final rule requires the States to determine the rate 
of progress for remedying existing impairment that is reasonable, 
taking into consideration the statutory factors, and informed by 
input from all stakeholders.'' \70\
---------------------------------------------------------------------------

    \70\ 64 FR 35731.

    The EPA's 2007 guidance for setting RPGs (referred to hereafter as 
EPA's RPG Guidance) states the following with regard to the statutory 
---------------------------------------------------------------------------
factors under 40 CFR 51.308(d)(1)(i)(A):

    ``The regional haze rule requires you to clearly support your 
RPG determination in your SIP submission based on the statutory 
factors.'' \71\
---------------------------------------------------------------------------

    \71\ See EPA's Guidance for Setting Reasonable Progress Goals 
Under the Regional Haze Program (June 1, 2007), Section 2.4.

    Therefore, it is clear that the Arkansas RH SIP has fallen short of 
its obligations with regard to RPG requirements under the RHR and 
applicable EPA guidance.
    The EPA agrees that states generally must consider the reasonable 
progress factors (i.e. the four statutory factors) under 40 CFR 
51.308(d)(1)(i)(A) and the URP in establishing RPGs. The EPA also 
agrees that EPA guidance states that it is not necessary for states to 
reassess the reasonable progress factors for sources subject to BART 
for which the state has already completed a full five factor BART 
analysis.\72\ However, the requirement in the RHR and EPA's RPG 
guidance for states to consider the four statutory factors applies to 
all point sources (and non-point sources if appropriate), and as such, 
is not limited only to sources that are subject to BART. In 
establishing RPGs, states must still consider the four statutory 
factors for sources that are not subject to BART. EPA's guidance for 
establishing RPGs states the following:
---------------------------------------------------------------------------

    \72\ See EPA's Guidance for Setting Reasonable Progress Goals 
Under the Regional Haze Program (June 1, 2007), Section 5.0.

    ``The discussion of the statutory factors in this guidance is 
largely aimed at helping States apply these factors in considering 
measures for point sources. States may find that the factors can be 
applied to sources other than point sources; the meaning of the 
factors, however, should not be unduly strained in order to fit non-
point sources.'' \73\
---------------------------------------------------------------------------

    \73\ See EPA's Guidance for Setting Reasonable Progress Goals 
Under the Regional Haze Program (June 1, 2007), Section 1.2.

    As such, what warrants EPA's disapproval of Arkansas's RPGs is that 
in establishing its RPGs, the State did not evaluate the four statutory 
factors for sources that are not subject to BART, as required under 40 
CFR 51.308(d)(1)(i)(A). Arkansas's lack of RPG analysis is especially 
troublesome in light of several sources not subject to BART which 
contribute to the impairment of visibility above 0.5 dv, as explained 
in more detail in our proposed rulemaking. To satisfy the RHR 
requirements, the State must do more than just consider the URP in 
establishing RPGs. As explained in our proposed rulemaking on the 
Arkansas RH SIP, the RHR provides that EPA will consider both the 
State's consideration of the four factors in 40 CFR 51.308(d)(1)(i)(A) 
and its analysis of the URP in determining whether the State's goal for 
visibility improvement provides for reasonable progress.\74\ Therefore, 
the State must still consider the four statutory factors under 40 CFR 
51.308(d)(1)(i)(A), even if the CENRAP's modeling demonstrated that the 
measures included in the SIP exceed those necessary to meet the URP for 
the first implementation period for both of Arkansas's Class I areas. 
The RHR and EPA's guidance for establishing RPGs do not provide that a 
State may forego an analysis of the four statutory factors if modeling 
demonstrates that it is expected to meet the URP in 2018 for both of 
its Class I areas. EPA agrees with the commenter that states have 
considerable discretion in determining RPGs. Nevertheless, there are 
several requirements that states must meet in establishing their RPGs, 
and where EPA determines that these requirements have not been 
satisfied, EPA has the authority to disapprove the State's RPGs and 
indeed must disapprove it as not meeting the Federal requirements.
---------------------------------------------------------------------------

    \74\ 64 FR 35766.
---------------------------------------------------------------------------

    In our disapproval of the State's RPGs, EPA is not substituting its 
judgment for that of the State. Our disapproval is not based on a 
disagreement with the State with regard to the value of the State's 
RPGs, rather our disapproval is based on the fact that the State did 
not evaluate the four statutory factors in establishing its RPGs, 
especially given that known sources of visibility impairment were not 
analyzed. We note that, at this point, it is not possible to know 
whether different RPGs are appropriate for Arkansas's Class I areas. 
Until the State conducts a proper evaluation of the four statutory 
factors, in accordance with the CAA Sec.  169A(g)(1), 40 CFR 
51.308(d)(1)(i)(A), and EPA's RPG Guidance, or EPA conducts such 
evaluation in the context of a FIP, we will not know whether different 
RPGs are appropriate for Arkansas's Class I areas.
    Comment: The EPA properly approved Arkansas's URP, but improperly 
applied the URP when analyzing Arkansas's BART determinations and RPGs. 
EPA acknowledges that the measures Arkansas adopted in the RH SIP would 
meet the URP, but EPA still partially disapproved the Arkansas RH SIP 
in part because ADEQ did not undertake any ``further analysis'' after 
determining its RPGs would meet or exceed the URP. EPA's claim that 
Arkansas is required to undertake any further analysis lacks a legal 
basis, as states are not required to go beyond the URP analysis in 
establishing RPGs. Neither the CAA nor the RHR allow for the ``further 
analysis'' EPA is requiring of Arkansas regarding its RPGs and the URP. 
Courts have held that when an agency relies on factors which Congress 
has not intended it to consider, then such action is arbitrary and 
capricious (Arizona Public Service Company v. US EPA, 562 F.3d 1116, 
1123 (10th Cir. 2009)). The RHR explains that states must consider the 
uniform rate of improvement in visibility and the emissions reductions 
needed to achieve it when formulating RPGs, and since Arkansas has 
exceeded the URP when formulating its RPGs, Arkansas has met the legal 
requirements of the RHR. EPA should not have disapproved Arkansas's 
RPGs since they are consistent with the CAA and the visibility 
impairment regulations. The EPA's disapproval of Arkansas's RPGs 
elevates form over substance, and fails to recognize the purpose of 
RPGs in improving visibility impairment. The RHR only requires 
additional analysis when a state establishes RPGs that provide for a 
slower rate of improvement than the URP (40 CFR 51.308(d)(1)(ii).
    Response: The EPA disagrees that we improperly applied the URP when

[[Page 14622]]

analyzing Arkansas's BART determinations and RPGs. In fact, EPA did not 
consider the State's URP in evaluating the State's BART determinations 
because EPA does not have authority under the RHR to do so. With regard 
to the RPGs, EPA upholds its proposed disapproval of the State's RPGs 
because the State did not undertake an analysis of the four statutory 
factors, as required under 40 CFR 51.308(d)(1)(i)(A). While EPA agrees 
that the RHR requires states to consider the uniform rate of 
improvement in visibility when formulating RPGs, we disagree that a 
state's consideration of the URP and establishment of RPGs that provide 
for a slightly greater rate of improvement in visibility than would be 
needed to attain the URP is all that is needed to satisfy the RPG 
requirements in the RHR. EPA also disagrees that the RHR only requires 
additional analysis when a state establishes RPGs that provide for a 
slower rate of improvement than the URP. As explained in our proposed 
rulemaking on the Arkansas RH SIP, in establishing its RPGs, the State 
is required by CAA Sec.  169A(g)(1) and 40 CFR 51.308(d)(1)(i)(A) to 
``[c]onsider the costs of compliance, the time necessary for 
compliance, the energy and non-air quality environmental impacts of 
compliance, and the remaining useful life of any potentially affected 
sources, and include a demonstration showing how these factors were 
taken into consideration in selecting the goal.''
    The RHR states the following with regard to RPG requirements:

    ``Today's final rule requires the States to determine the rate 
of progress for remedying existing impairment that is reasonable, 
taking into consideration the statutory factors, and informed by 
input from all stakeholders.'' \75\
---------------------------------------------------------------------------

    \75\ 64 FR 35731.

    An analysis of the four statutory factors is precisely the 
``further analysis'' EPA refers to in its proposed rulemaking on the 
Arkansas RH SIP.\76\ As explained above, both the RHR and the CAA 
require states to undertake this analysis in establishing its RPGs. 
Therefore, EPA disagrees that our proposed rulemaking on the Arkansas 
RH SIP is arbitrary and capricious because it relies on factors which 
Congress has not intended it to consider. CAA section 169A(g)(1) 
clearly requires states to consider these four factors in establishing 
their RPGs. Accordingly, EPA's proposed disapproval of Arkansas's RPGs 
is consistent with the RH regulations and the Act. Because the CAA 
section 169A(g)(1) and 40 CFR 51.308(d)(1)(i)(A) require that states 
consider the four statutory factors in establishing their RPGs, a 
requirement which Arkansas has not satisfied, our proposed disapproval 
of Arkansas's RPGs recognizes the purpose of the RPGs in improving 
visibility impairment and is in keeping with the statutory 
requirements.
---------------------------------------------------------------------------

    \76\ 76 FR 64195.
---------------------------------------------------------------------------

    Comment: We agree with EPA's proposed disapproval of Arkansas's 
RPGs because no proper four-factor analysis was done in setting those 
goals. In setting its RPGs, the state is required to consider the four 
statutory factors and include a demonstration showing how these factors 
were taken into consideration in selecting the goal (40 CFR 
51.308(d)(1)(i)(A) and 42 U.S.C. 7491(g)(1)). As EPA stated in its 
proposed rulemaking, the RHR makes clear that just meeting the URP does 
not exempt a state from a proper four-factor evaluation of RPGs for the 
state's Class I areas (see 76 FR 64195 and 64 FR 35732). Being on the 
``glide path'' to achieve the URP does not by itself ensure that a 
Class I area will make reasonable progress to reach natural background 
visibility conditions by 2064 because the ``glide path'' assumes that 
increasing levels of reductions of visibility-impairing pollutants will 
consistently occur over the next 53 years until 2064. There is no 
guarantee that this will happen, and ADEQ has not indicated what 
controls will be required in the next 53 years to ensure they stay on 
the glide path. EPA ensures that all reasonable measures that can be 
implemented during the first planning period are implemented by 
requiring states to evaluate whether additional progress beyond the URP 
is reasonable in this first RH planning period. Considering that the 
modeling on which future predictions of visibility impairment levels 
are based has uncertainties both in the modeling itself and in the 
projections of emissions for various source categories, it is necessary 
that states be required to conduct a four-factor analysis to evaluate 
all the controls that could reasonably be implemented to make progress 
toward the national visibility goal.
    Response: The EPA agrees that Arkansas did not do a proper four-
factor analysis nor did it include a demonstration showing how these 
factors were taken into consideration in selecting the goal in 
accordance with the CAA and the RHR. Please see elsewhere in our 
response to other comments for an explanation of the requirements for 
establishing RPGs.
    Comment: The EPA has proposed to partially disapprove Arkansas's 
LTS for failure to include adequate emissions limitations as required 
under 40 CFR 51.308(d)(3)(v)(C) due to the fact that the State relied 
on its BART emission limits to satisfy this LTS requirement and EPA is 
proposing to disapprove the majority of those BART emission limits (76 
FR 64218). The EPA has proposed to approve the remaining elements of 
the Arkansas LTS. EPA should not partially approve any part of 
Arkansas's LTS when EPA has proposed to disapprove Arkansas's RPGs. A 
State's LTS is the State's plan to ensure that reasonable progress 
towards achieving natural background conditions is achieved both at the 
State's Class I areas and at out-of-state Class I areas impacted by 
sources within the State (40 CFR 51.308(d)(3). If the State's RPGs are 
not approvable, then no part of the State's LTS should be approved 
because the purpose of the LTS is to reflect the State's plan for 
assuring reasonable progress, which is in turn based on the State's 
RPGs. The Arkansas LTS should be disapproved in its entirety.
    Response: While EPA agrees that a state's LTS is its plan to ensure 
that reasonable progress towards achieving natural background 
conditions is achieved both at the state's Class I areas and at out-of-
state Class I areas impacted by sources within the state,\77\ EPA 
disagrees that no part of a state's LTS should be approved even if the 
state's RPGs are not approvable. As explained in our proposed 
rulemaking on the Arkansas RH SIP, the LTS is a compilation of state-
specific control measures relied on by the states for achieving their 
RPGs.\78\ Regardless of what RPGs a state establishes (and whether or 
not EPA approves these RPGs), state-specific control measures will help 
the state make progress towards improving visibility. Even though these 
control measures may not ensure that a state's RPGs will be met, 
especially in cases such as this where EPA is disapproving the State's 
RPGs, the control measures that the State has relied on in the LTS for 
achieving its RPGs (with the exception of the BART determinations we 
are disapproving) will aid the State in achieving reasonable progress.
---------------------------------------------------------------------------

    \77\ 40 CFR 51.308(d)(3).
    \78\ 76 FR 64212.
---------------------------------------------------------------------------

    Furthermore, 40 CFR 51.308(d)(3)(v) requires that states consider 
certain factors in developing their LTS. These LTS factors are: (A) 
Emission reductions due to ongoing air pollution control programs, 
including measures to address RAVI; (B) measures to mitigate the 
impacts of construction activities; (C) emissions limitations and 
schedules for compliance to achieve the

[[Page 14623]]

reasonable progress goal; (D) source retirement and replacement 
schedules; (E) smoke management techniques for agricultural and 
forestry management purposes including plans as currently exist within 
the state for these purposes; (F) enforceability of emissions 
limitations and control measures; and (G) the anticipated net effect on 
visibility due to projected changes in point, area, and mobile source 
emissions over the period addressed by the LTS. As explained in our 
proposed action on the Arkansas RH SIP, we are finding that Arkansas 
had appropriately considered these factors, with the exception of the 
factor under 40 CFR 51.308(d)(3)(v)(C), which requires the State to 
consider emission limitations and schedules for compliance to achieve 
the RPGs. Therefore, with the exception of this element, we are finding 
that the LTS satisfies the requirements of 40 CFR 51.308(d)(3). 
Furthermore, we point out that satisfaction of some of the requirements 
under 40 CFR 51.308(d)(3) is not intrinsically tied to or conditioned 
upon a specific dv value for the RPG. Therefore, disapproval of the 
RPGs does not mean automatic disapproval of all elements of the LTS. We 
are finalizing our proposed partial approval and partial disapproval of 
Arkansas's LTS.
    Comment: According to EPA's TSD for the Arkansas RH SIP, Arkansas 
Class I areas are impacted by sources from outside the State as well as 
by sources within the State. In 2018, Arkansas sources are projected to 
be the top contributor to visibility impairment at Caney Creek and 
Upper Buffalo. The contribution from Arkansas's sources at the Class I 
areas in Arkansas, Missouri, Oklahoma, and other states is projected to 
increase in 2018 from 2002 levels. It appears that the projected 
improvement in visibility in 2018 for Caney Creek and Upper Buffalo is 
mainly due to significant projected emission reductions from sources in 
Texas. Even if other states are requiring emission reductions at the 
sources that cause and contribute to visibility impairment in 
Arkansas's Class I areas, Arkansas still has an obligation under its 
LTS to adopt control measures adequate to address its contribution to 
visibility impairment in the State's Class I areas. The Federal RH 
regulations require that ``where other States cause or contribute to 
impairment in a mandatory Class I Federal area, the State must 
demonstrate that it has included in its implementation plan all 
measures necessary to obtain its share of the emissions reductions 
needed to meet the progress goal for the area'' (see 40 CFR 
51.308(d)(3)(ii)). Therefore, as part of the LTS, Arkansas is required 
to identify all sources of visibility impairment in the State and 
should have considered the adoption of emission limitations and 
compliance schedules for those sources to achieve natural background 
visibility conditions at Arkansas's Class I areas. Arkansas failed to 
properly evaluate these emission limitations and compliance schedules.
    Response: The EPA agrees that Arkansas Class I areas are impacted 
by sources from outside the State as well as by sources within the 
State, and that modeling demonstrates that Arkansas sources are 
projected to be the top contributor to visibility impairment at Caney 
Creek and Upper Buffalo in 2018. EPA also agrees that the contribution 
of Arkansas sources to visibility impairment at Class I areas in 
Arkansas, Missouri, Oklahoma, and other states is projected to increase 
in 2018 from baseline levels.
    Under 40 CFR 51.308(d)(3), states must submit a LTS that addresses 
visibility impairment for each Class I area within the State and for 
each Class I area located outside the State which may be affected by 
emissions from the State. Arkansas has done this, and we are partially 
approving and partially disapproving that LTS, as explained in more 
detail in our proposed rulemaking and discussed elsewhere in our 
response to other comments. Under 40 CFR 51.308(d)(3)(i), states that 
are reasonably anticipated to contribute to visibility impairment in 
any Class I area located in another state are required to consult with 
the other state to develop coordinated emission management strategies. 
States are also required to consult with any other states that are 
reasonably anticipated to contribute to visibility impairment in any 
Class I area within the state. As explained in our proposed rulemaking, 
Arkansas satisfied this requirement through its consultation with 
affected states. Under 40 CFR 51.308(d)(3)(ii), where other states 
cause or contribute to impairment in a Class I area, the State must 
demonstrate that it has included in its implementation plan all 
measures necessary to obtain its share of the emissions reductions 
needed to meet the progress goals for the area. States can meet this 
requirement through participation in a regional planning process where 
all potentially affected states are consulted, and by ensuring that 
they have included all measures needed to achieve their apportionment 
of emission reduction obligations agreed upon through that process. As 
explained in our proposed rulemaking on the Arkansas RH SIP, we are 
finding that Arkansas satisfied its consultation requirements when 
establishing its LTS.\79\ Therefore, EPA is finding that the Arkansas 
RH SIP satisfies the requirements under 40 CFR 51.308(d)(3)(i) and 
(ii).
---------------------------------------------------------------------------

    \79\ 76 FR 64216.
---------------------------------------------------------------------------

    The EPA agrees that as part of setting RPGs and developing a LTS, 
Arkansas is required to identify sources of visibility impairment in 
the State and to establish ``emission limitations, schedules of 
compliance and other measures as may be necessary to make reasonable 
progress toward the national goal.'' In developing a RH SIP, the state 
accordingly must consider whether there are reasonable measures that 
should be adopted. A state is also required to consider the adoption of 
emission reduction measures needed to achieve the URP. The RHR does not 
require a state to consider what measures would be necessary to achieve 
natural background visibility conditions at Arkansas's Class I areas. 
EPA does, however, agree that Arkansas failed to properly evaluate 
whether there were any reasonable measures beyond BART that could have 
been adopted to improve visibility.
    Comment: The fact that emissions of SO2, NOX, 
and other visibility impairing pollutants are projected to increase in 
2018 compared to 2002 levels, indicates that Arkansas is not doing all 
it can to address the sources of visibility-impairment that exist in 
the State of Arkansas. There are additional control measures Arkansas 
should have considered for adoption as part of its LTS. For example, 
ADEQ's BART emission limits for White Bluff Units 1 and 2 and Flint 
Creek do not reflect the top levels of emissions control achievable at 
Arkansas's subject to BART sources, nor do the emission limits reflect 
the capabilities of the control equipment that has been proposed to be 
installed. If not required to meet lower SO2 limits as BART, 
ADEQ should evaluate lower SO2 limits to ensure reasonable 
progress toward achieving natural background visibility conditions. 
Also, ADEQ did not evaluate installation of post-combustion controls 
such as SCR to meet the NOX BART requirements for White 
Bluff Units 1 and 2 or Flint Creek Boiler No. 1. The data on the worst 
20% days for Caney Creek shows that nitrates are often the major 
component of visibility impairment during the winter months and the 
data on the best 20% days for Caney Creek shows that nitrates are more 
often the major component of visibility impairment. At Upper Buffalo, 
nitrates are the major component of

[[Page 14624]]

visibility impairment in the winter months as well, and nitrates are 
also a major component of visibility impairment in the spring and fall 
months. The Missouri Class I areas show similar patterns. The 2018 
modeling projections show that nitrates continue to be a major 
component of visibility impairment during the winter months on the 20% 
worst days at Caney Creek. Therefore, if post-combustion controls are 
not required as BART for White Bluff Units 1 and 2 and Flint Creek 
Boiler No. 1, then the State should be required to evaluate 
installation of post-combustion controls at these sources to meet 
reasonable progress requirements. If not ultimately required to meet 
lower SO2 limits or the installation of SCR as BART, the 
State should evaluate lower limits and additional controls on 
SO2 and NOX to ensure reasonable progress is made 
toward natural background visibility conditions.
    Response: The EPA agrees that emissions of visibility impairing 
pollutants in Arkansas are projected to increase in 2018 from baseline 
levels, and that in establishing its RPGs and LTS, the State has not 
appropriately considered whether there are additional measures that 
would be reasonable for addressing visibility impairment. That 
emissions of SO2, NOX, and other visibility 
impairing pollutants in Arkansas are projected to increase suggests 
that the state should carefully consider what measures can be adopted 
to ensure that the state contributes to improving visibility in the 
region. EPA also agrees that Arkansas's NOX and 
SO2 BART emission limits for White Bluff Units 1 and 2 and 
Flint Creek Boiler No. 1 do not reflect the most stringent level of 
emissions control achievable at Arkansas's subject to BART sources. As 
explained in our proposed rulemaking on the Arkansas RH SIP, we are 
disapproving the State's SO2 and NOX BART 
determinations for White Bluff Units 1 and 2 and Flint Creek Boiler No. 
1 because Arkansas limited its BART determinations to considering the 
measures necessary for achieving the presumptive limits and did not 
appropriately consider whether more stringent controls or emission 
limits were appropriate based on a consideration of the five statutory 
factors, as required by 40 CFR 51.308(e)(1)(ii)(A) and section 
169A(g)(2) of the CAA. However, EPA disagrees that if we ultimately 
approve BART determinations that do not require White Bluff Units 1 and 
2 and Flint Creek Boiler No. 1 to install post-combustion controls and/
or do not require these sources to establish SO2 and 
NOX BART emission limits more stringent than those currently 
adopted by the State, Arkansas is required to evaluate post-combustion 
controls and more stringent SO2 and NOX limits 
for its subject to BART sources to satisfy the reasonable progress 
requirements at 40 CFR 51.308(d)(1). Because the BART analysis that is 
required for subject to BART sources is based, in part, on an 
assessment of many of the same factors that must be addressed in 
establishing a state's RPGs, EPA's guidance for establishing RPGs 
provided that it is reasonable for a State to conclude that any control 
requirements imposed in the BART determination also satisfy the RPG-
related requirements for source review in the first RPG planning 
period.\80\ EPA's guidance states the following:
---------------------------------------------------------------------------

    \80\ See EPA's Guidance for Setting Reasonable Progress Goals 
Under the Regional Haze Program (June 1, 2007), Section 4.2.

    ``Also, as noted in section 4.2, it is not necessary for you to 
reassess the reasonable progress factors for sources subject to BART 
for which you have already completed a BART analysis.'' \81\
---------------------------------------------------------------------------

    \81\ See EPA's Guidance for Setting Reasonable Progress Goals 
Under the Regional Haze Program (June 1, 2007), Section 5.0.

    Therefore, we note that once EPA has approved the BART 
determination for a particular pollutant for a given subject to BART 
source, the State is not required to evaluate the reasonable progress 
factors for that particular pollutant for the given source in order to 
satisfy the reasonable progress requirements.
    Comment: There are additional control measures Arkansas should have 
considered for adoption as part of its LTS. Arkansas must consider 
controls for other point sources in the State that are not subject to 
BART but that could be required to reduce emission to help Arkansas and 
other affected states assure reasonable progress towards achieving 
background visibility conditions. For example, Arkansas should evaluate 
controls for Entergy's Independence Power Plant, which is located 
approximately 140 km from Upper Buffalo, and is the second largest 
source of SO2 and NOX emissions in Arkansas 
(Entergy White Bluff is the first). Once the White Bluff power plant 
installs controls to meet BART for SO2 and NOX, 
the Independence plant will be the largest source of SO2 and 
NOX in the State. The Independence plant was not identified 
by ADEQ as BART-eligible. It consists of two coal-fired units that have 
no SO2 control technology installed with a generating 
capacity of 1700 MW (see Exhibit 23). PM emissions are controlled with 
electrostatic precipitators (ESPs) and NOX emissions are 
controlled only with overfire air. Despite its size and location, the 
Arkansas RH SIP did not identify the Independence plant as a possible 
source of visibility impairment. Upgraded combustion controls and/or 
installation of SCR should be evaluated for control of NOX 
emissions, and the installation of a scrubber should be evaluated for 
control of SO2 emissions. Arkansas should be required to 
evaluate these as well as additional control measures to ensure it is 
doing all it can to provide for reasonable progress toward meeting 
natural visibility conditions at the State's Class I areas and at the 
Class I areas impacted by Arkansas sources.
    Response: EPA agrees that Arkansas must consider controls for point 
sources in the State that are not subject to BART but that could be 
required to reduce emissions to help Arkansas and other affected states 
assure reasonable progress towards achieving background visibility 
conditions. We do note that the RHR and EPA's guidance for establishing 
RPGs give states flexibility in determining which particular sources to 
evaluate and how to take into consideration the four statutory factors. 
EPA's guidance for establishing RPGs provide the following:

``In determining reasonable progress, CAA Sec.  169A(g)(1) requires 
States to take into consideration a number of factors. However, you 
have flexibility in how to take into consideration these statutory 
factors and any other factors that you have determined to be 
relevant. For example, the factors could be used to select which 
sources or activities should or should not be regulated, or they 
could be used to determine the level or stringency of control, if 
any, for selected sources or activities, or some combination of 
both.'' \82\
---------------------------------------------------------------------------

    \82\ See EPA's Guidance for Setting Reasonable Progress Goals 
Under the Regional Haze Program (June 1, 2007), Section 5.0.

    As the Entergy Independence Power Plant has significant emissions 
and emissions reductions from the source would likely help Arkansas and 
other affected states assure reasonable progress, EPA agrees that the 
Entergy Independence Power Plant is a good candidate for further 
consideration by Arkansas. As we are disapproving Arkansas's RPGs, the 
State will need to consider whether controls at this facility and any 
other facilities would be reasonable for purposes of addressing 
visibility impairment.
    Comment: In addition to Caney Creek and Upper Buffalo, sources in 
Arkansas also contribute to visibility impairment

[[Page 14625]]

in Missouri's two Class I areas (Mingo and Hercules Glades) and 
Oklahoma's Class I area (Wichita Mountains). Even though Arkansas 
claims it does not need to adopt any additional measures in its LTS 
because the CENRAP 2018 modeling showed that the emissions reductions 
planned in CENRAP states were sufficient for Missouri's Class I areas 
to meet their RPGs, EPA has not proposed action on the Missouri RH SIP, 
and it is not clear if EPA will be approving Missouri's RPGs. Also, the 
CENRAP 2018 modeling Missouri relied on may be underestimating impacts 
due to sulfates, as indicated by EPA in Appendix A to the TSD for the 
Arkansas RH SIP. For the Mingo Class I area in Missouri, since there 
was not sufficient capture of valid IMPROVE data to determine baseline 
conditions in accordance with EPA guidance, it is not clear whether the 
CENRAP modeling shows that the projected visibility improvements at 
Mingo will meet or exceed the URP toward attaining background 
visibility conditions. Therefore, Arkansas cannot rely on Missouri's 
claims that it is meeting its RPGs to justify avoiding the evaluation 
of additional control measures for sources of visibility-impairing 
pollutants in Arkansas. In addition, Arkansas sources contributed 2.0% 
to visibility impairment at Wichita Mountains during the baseline 
period and are projected to contribute 2.3% in 2018. This may appear to 
be a small contribution, but it is a contribution nonetheless. Oklahoma 
apparently does not agree with ADEQ that Arkansas's source 
contributions are insignificant. Since the Wichita Mountains is not 
expected to achieve the necessary improvements in visibility in 2018 to 
meet or exceed the URP, Arkansas should be required to evaluate 
emission controls that could be required at Arkansas sources that 
impact visibility at the Wichita Mountains. Arkansas has an obligation 
as part of its LTS to evaluate and adopt those control measures 
necessary to address Arkansas's share of visibility impairment in Class 
I areas in Missouri and Oklahoma (40 CFR 51.308(d)(3)(ii)).
    Response: We disagree that because EPA has not proposed action on 
the Missouri RH SIP, we cannot find that Arkansas does not need to 
adopt any additional measures in its LTS. We find that we have the 
authority to act on Arkansas's LTS now.
    In the context of acting on the LTS and Arkansas's RH SIP, the 
comment raises a concern with missing data at the Mingo Wilderness 
Area's IMPROVE monitor, and refers to a statement in the CENRAP TSD 
that because of a lack of data it did not meet EPA's data acceptance 
criteria. The Mingo monitor had a wasp type nest inside the collection 
apparatus for the Organic Carbon sampling stream that may have impacted 
the air flow and sampling for these specific pollutants, but not the 
other sampling streams. The other pollutants, including nitrates and 
sulfates (NOX and SO2 products) were collected 
for the entire baseline time period without the need for data 
substitution. The IMPROVE group did evaluate two different approaches 
to backfill the missing data for the organics and Elemental Carbon that 
resulted in nearly identical results. They then selected the method 
that they thought was most appropriate in backfilling the data based on 
other monitoring data collected. This backfill data was then used with 
the rest of the monitored data for the baseline for the Mingo monitor. 
The IMPROVE group is made up of a number of experts in these specific 
issues and we concur that the approach is acceptable for use in 
establishing the baseline. It is very important to note that the 
Organic Carbon is a significantly smaller component of the visibility 
impairment than the amount of impairment from ammonium nitrate and 
ammonium sulfate at Mingo. We do not believe any inaccuracies in the 
backfill information for organic carbon would significantly impact the 
baseline at Mingo.\83\
---------------------------------------------------------------------------

    \83\ Chuck McDate and Warren White UC Davis, Power Point from 
Inter-RPO Data Analysis/Monitoring Workgroup 9/28/05 ``Approach for 
Substituting Mingo IMPROVE Carbon Data'', RPO Call 092805 Mingo.ppt; 
Archuleta, et al. Extended Abstract 58 ``IMPROVE Data 
Substitution Methods for Regional Haze'', 58-Archuleta.pdf; Graphic 
of comparison of two technique results, Out.pdf; Communications 
record between Scott Copeland CIRA--Cooperative Institute for 
Research in the Atmosphere with Erik Snyder, EPA Region 6, February 
10, 2012.
---------------------------------------------------------------------------

    With regard to the establishment of a state's LTS, 40 CFR 
51.308(d)(3)(i) states the following:

    ``Where the State has emissions that are reasonably anticipated 
to contribute to visibility impairment in any mandatory Class I area 
located in another State or States, the State must consult with the 
other State(s) in order to develop coordinated emission management 
strategies.''

    As explained in our proposed rulemaking on the Arkansas RH SIP, 
CENRAP's photochemical modeling demonstrated that besides Arkansas's 
own Class I areas, the only Class I areas where Arkansas sources can be 
said to be contributing to visibility impairment are the Mingo 
Wilderness Area and the Hercules Glades Wilderness Area in Missouri and 
not Wichita Mountains in Oklahoma. Arkansas considered modeling that 
was performed by the CENRAP and consulted with Missouri, Oklahoma, and 
other potentially affected states. In its consultation with Missouri, 
both Arkansas and Missouri determined that it was not necessary for 
Arkansas to commit to additional emission reductions since the CENRAP 
modeling showed that emission reductions already planned by the CENRAP 
and other states would be sufficient for Missouri's Class I areas to 
meet their RPGs (notwithstanding the uncertainties that may have been 
involved in the modeling). We note that Arkansas will be considering 
whether additional emission reduction measures are reasonable for 
improving visibility at the Class I areas within Arkansas and 
revisiting several of its BART determinations. Any more stringent 
measures adopted by Arkansas to address the deficiencies we have 
identified in its RH SIP have the potential to also benefit visibility 
at Mingo and Hercules Glades. When we take action on the Missouri RH 
SIP, we will consider whether Missouri's RPGs are appropriate.
    With regard to the comment that Arkansas sources contributed 2.0% 
to visibility impairment at Wichita Mountains during the baseline 
period and are projected to contribute 2.3% in 2018, EPA notes that 
removal of this 2.3% contribution to the total extinction results in a 
visibility improvement of only 0.2 dv from the 2018 projected 
visibility conditions. Although the Oklahoma Department of 
Environmental Quality (ODEQ) initially believed that emissions from 
Arkansas sources are impacting visibility at Wichita Mountains and that 
it might be necessary for Arkansas to commit to additional emissions 
reductions, Arkansas responded to ODEQ's concerns with a letter dated 
August 17, 2007, explaining that based on photochemical modeling, ADEQ 
had calculated that the total visibility impact from all sources in 
Arkansas at Wichita Mountains is 0.2dv.\84\ Furthermore, in section 
X.A. of the Oklahoma RH SIP submitted to EPA, ODEQ references the 
August 17, 2007 letter sent by ADEQ and states that it is in agreement 
with the projected emissions reductions from Arkansas and all other 
states with which it consulted with regard to visibility impairment at 
Wichita Mountains.
---------------------------------------------------------------------------

    \84\ See letter from Mike Bates, Air Division Director, Arkansas 
Department of Environmental Quality, to Eddie Terrill, Air Division 
Director, Oklahoma Department of Environmental Quality, dated August 
17, 2007. This letter is found in Appendix 10.3 of the Arkansas RH 
SIP.

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

[[Page 14626]]

    Consequently, while we are concerned that the RPG at Wichita 
Mountains is not on the glide path, we believe the technical assessment 
that Arkansas sources do not have a significant impact at Wichita 
Mountains is accurate and ADEQ and ODEQ followed consultation 
procedures. We therefore disagree that Arkansas must adopt additional 
control measures to address its visibility impact at other states' 
Class I areas. Considering the modeling results and since both states 
agreed to this on the results of the consultations, we find that 
Arkansas has satisfied its obligations under 40 CFR 51.308(d)(3)(i) and 
(ii).
    Comment: The EPA criticizes Arkansas for not conducting the four 
factor RPG analysis. However, EPA's guidance only requires a four 
factor analysis for potentially affected sources. Because Arkansas 
determined that emission reductions anticipated from implementation of 
BART and other CAA programs during the initial planning period are 
sufficient to satisfy the URP, it is not required to consider 
additional emission reductions from other potentially affected sources 
in setting its RPGs. This approach is supported by EPA's RPG Guidance, 
which opines that only BART and other existing CAA programs may be all 
that are necessary to achieve reasonable progress in the first planning 
period for some states. The EPA is incorrect that ADEQ relied solely on 
meeting the URP to reach its RPG determination. ADEQ relied on EPA 
guidance indicating the application of BART alone could be considered 
as constituting reasonable progress for the first planning period. 
Arkansas determined its URP. Arkansas participated in CENRAP, 
coordinated with Missouri Department of Natural Resources, and 
consulted with other states who may contribute to RH in Arkansas Class 
I areas. ADEQ also used modeling projections that show that the 
combination of already mandated controls, including BART emissions 
limitations, will provide for a rate of progress that improves 
visibility conditions and results in the attainment of natural 
visibility conditions by 2064. This modeling also demonstrated that the 
RPGs for Arkansas's Class I areas are better than the URP. This is 
consistent with the requirements of the CAA and EPA's regulations and 
guidance. Thus, Arkansas's RPGs should be approved by EPA.
    Response: With regard to the comment that EPA's guidance only 
requires a four factor analysis for potentially affected sources, we 
note that EPA's RPG Guidance states the following:

``In determining reasonable progress, CAA Sec.  169A(g)(1) requires 
States to take into consideration a number of factors. However, you 
have flexibility in how to take into consideration these statutory 
factors and any other factors that you have determined to be 
relevant. For example, the factors could be used to select which 
sources or activities should or should not be regulated, or they 
could be used to determine the level or stringency of control, if 
any, for selected sources or activities, or some combination of 
both.'' \85\
---------------------------------------------------------------------------

    \85\ See EPA's Guidance for Setting Reasonable Progress Goals 
Under the Regional Haze Program (June 1, 2007), Section 5.0.

---------------------------------------------------------------------------
    EPA's guidance for setting RPGs also provides that:

    ``The RHR gives States wide latitude to determine additional 
control requirements, and there are many ways to approach 
identifying additional reasonable measures; however, you must at a 
minimum, consider the four statutory factors. Based on the 
contribution from certain source categories and the magnitude of 
their emissions you may determine that little additional analysis is 
required to determine further controls are not warranted for that 
category.'' \86\
---------------------------------------------------------------------------

    \86\ See EPA's Guidance for Setting Reasonable Progress Goals 
Under the Regional Haze Program (June 1, 2007), Section 4.2.

    Although the State has flexibility in how to consider the four 
statutory factors, it must consider these four factors in some form. 
The State made no attempt to do this in the Arkansas RH SIP. Even if 
emission reductions anticipated from implementation of BART and other 
CAA programs during the initial planning period are expected to result 
in a slightly greater rate of improvement in visibility than would be 
needed to attain the URP for the first implementation period, the State 
must still consider whether any additional control measures would be 
reasonable, based on its consideration of the relevant factors. 
Arkansas's actions are especially problematic as there are sources that 
are not subject to BART but which contribute to visibility impairment 
above the State's established BART threshold of 0.5 dv. While EPA 
agrees that EPA's RPG Guidance states that BART and other existing CAA 
programs may be all that is necessary to achieve reasonable progress in 
the first planning period for some states, Arkansas's approach is not 
supported by our RPG Guidance.\87\ EPA's guidance states that BART and 
other existing CAA programs may be all that is necessary, not that it 
is in fact all that is necessary. If the State believes that it is not 
necessary to require any sources to install controls under the 
reasonable progress requirements (i.e. that there are no ``potentially 
affected sources''), it must demonstrate this through its consideration 
of the four statutory factors.
---------------------------------------------------------------------------

    \87\ See EPA's Guidance for Setting Reasonable Progress Goals 
Under the Regional Haze Program (June 1, 2007), Section 4.1.
---------------------------------------------------------------------------

    As discussed in our proposed rulemaking on the Arkansas RH SIP, we 
agree that the State properly determined its URP, and that the State 
participated in CENRAP and coordinated and consulted with other states 
who may be contributing to visibility impairment in Arkansas's Class I 
areas. We find that Arkansas satisfies these requirements under the 
RHR. However, that is not all that a state is required to do in 
establishing its RPGs. In establishing its RPGs for any Class I area, a 
state must ``consider the costs of compliance, the time necessary for 
compliance, the energy and non-air quality environmental impacts of 
compliance, and the remaining useful life of any potentially affected 
sources, and include a demonstration showing how these factors were 
taken into consideration in selecting the goal.'' \88\ The Arkansas RH 
SIP does not satisfy this requirement.
---------------------------------------------------------------------------

    \88\ 40 CFR 51.308(d)(1)(i)(A).
---------------------------------------------------------------------------

    With regard to the comment that modeling projections show that the 
combination of already mandated controls will provide for a rate of 
progress that improves visibility conditions and result in the 
attainment of natural visibility conditions by 2064, EPA notes that the 
CENRAP modeled the projected visibility conditions anticipated at each 
Class I area in 2018. The CENRAP modeling is based on emissions 
reductions expected to result from Federal, State, and local control 
programs that are either currently in effect or with mandated future-
year emission reduction schedules that predate 2018. The CENRAP 
modeling itself did not show that already mandated controls are 
expected to attain natural visibility conditions by 2064. Rather, the 
rate of visibility improvement anticipated by the CENRAP modeling in 
2018, if sustained, would result in a return to natural visibility 
conditions prior to 2064. Therefore the comment that Arkansas is 
expected to ultimately achieve the national goal prior to 2064 assumes 
that the same level of reductions of visibility-impairing pollutants 
that is expected to occur during the first implementation period ending 
in 2018 will increasingly occur during each implementation period until 
the final implementation period ending in 2064. However, there is no 
guarantee that this will occur. The Arkansas RH SIP addresses the 
requirements of the RHR only for the first implementation period

[[Page 14627]]

ending in 2018. As such, EPA disagrees that we should approve 
Arkansas's RPGs because modeling demonstrates that Arkansas is expected 
to achieve the national goal prior to 2064.
    Comment: The EPA should not have disapproved Arkansas's LTS since 
it is consistent with the CAA and the visibility impairment 
regulations. The EPA is proposing to disapprove Arkansas's LTS because 
Arkansas relied on the emissions reductions and schedules of compliance 
associated with Arkansas's BART determinations. The EPA's reliance on 
its disapproval of Arkansas's BART determinations as a basis for 
disapproving the LTS treads on the state's authority under the CAA. The 
EPA's disapproval of Arkansas's LTS elevates form over substance, 
disregards the underlying purpose of the visibility protection program, 
and does not recognize the purpose of the LTS. Arkansas's LTS complies 
with the CAA. The applicable regulations require each state to submit a 
long-term, 10- to 15- year strategy for making reasonable progress 
toward the national goal of natural visibility conditions in 2064. 
Given that Arkansas's LTS includes emission limits, compliance 
schedules and other measures necessary to achieve reasonable progress 
toward the national visibility goal and to ultimately achieve natural 
visibility prior to 2064, the EPA's proposed disapproval is baseless 
and further shows that EPA is acting beyond the scope of the visibility 
protection requirements of the CAA.
    Response: We disagree that Arkansas's LTS fully satisfies the 
requirements of the CAA and the RH regulations. With regard to the LTS, 
the CAA requires that states establish:

    ``[A] long-term (ten to fifteen years) strategy for making 
reasonable progress toward meeting the national goal specified in 
subsection (a) of this section.'' \89\
---------------------------------------------------------------------------

    \89\ CAA section 169A(b)(2)(B).

    Consistent with the requirement of the CAA, 40 CFR 51.308(d)(3) 
requires that states include in their RH SIPs a LTS that includes 
``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.\90\ 
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.\91\ Since 40 CFR 
51.308(d)(3)(v)(C) requires that in developing its LTS, Arkansas 
consider emissions limitations and schedules of compliance to achieve 
the RPGs, the State included the BART emission limits it established 
for its subject to BART sources as part of its LTS. As explained in our 
proposed rulemaking on the Arkansas RH SIP, the BART emission limits 
established by Arkansas are an element of the LTS, and because we are 
disapproving a portion of Arkansas's BART determinations, it follows 
that the State did not properly consider emission limitations and 
schedules for compliance to include in its LTS, as required under 40 
CFR 51.308(d)(3)(v)(C). Therefore, we cannot approve this element of 
the LTS. Furthermore, as pointed out in one of the comments we 
received, since Arkansas did not consider the four statutory factors 
under 40 CFR 51.308(d)(1)(i)(A) when establishing its RPGs, it is not 
possible to know at this point whether requiring additional controls 
for Arkansas source categories affecting visibility constitutes 
reasonable progress. Therefore, we find that Arkansas's LTS does not 
include those measures necessary to achieve reasonable progress toward 
the national visibility goal. This is in support of the finding that 
Arkansas has not properly considered emission limitations and schedules 
for compliance in establishing its LTS, as required under 40 CFR 
51.308(d)(3)(v)(C).
---------------------------------------------------------------------------

    \90\ 40 CFR 51.308(d)(3).
    \91\ 40 CFR 51.308(d)(3)(v).
---------------------------------------------------------------------------

    We acknowledge that the CENRAP modeling shows that with the 
measures included in the RH SIP, Arkansas is projected to meet the URP 
for the first implementation period ending in 2018 for both of its 
Class I areas. However, with regard to the comment that Arkansas's LTS 
includes those measures necessary to ultimately achieve natural 
visibility prior to 2064, we note that the Arkansas's RH SIP (including 
the LTS) addresses the RHR requirements only for the first 
implementation period ending in 2018. The CENRAP modeling is based on 
emissions reductions expected to result from Federal, State, and local 
control programs that are either currently in effect or with mandated 
future-year emission reduction schedules that predate 2018. The CENRAP 
modeling itself did not show that already mandated controls are 
expected to attain natural visibility conditions by 2064. Rather, the 
rate of visibility improvement anticipated by the CENRAP modeling in 
2018, if sustained, will result in a return to natural visibility prior 
to 2064. This assumes that the same level of reductions of visibility-
impairing pollutants that is expected to occur during the first 
implementation period ending in 2018 will increasingly occur during 
each implementation period until the final implementation period ending 
in 2064. However, there is no guarantee that this will in fact occur.
    Comment: We agree with EPA's findings that ADEQ cannot rely solely 
on meeting the uniform rate of progress to conclude that its goals 
provide for reasonable progress. ADEQ needs to consider the four 
statutory factors required under 40 CFR 51.308(d)(1)(i)(A) to evaluate 
the potential controls for sources or source categories that contribute 
to visibility impairment.
    Response: As explained in our proposed rulemaking and elsewhere in 
our response to comments, Arkansas's lack of consideration of the four 
statutory factors required under the RHR is the grounds for our 
disapproval of Arkansas's RPGs.
    Comment: The EPA should disapprove Arkansas's LTS as well as the 
reasonable progress analysis because Arkansas's point sources emissions 
of SO2, the major pollutant contributing to visibility 
impairment in Arkansas's Class I area, are projected to increase 
instead of decreasing between 2002 and 2018. Source apportionment 
modeling by the CENRAP indicates that Arkansas's contribution to 
sulfate in Class I areas is projected to increase as contributions from 
surrounding states are projected to decrease. This is in contradiction 
to 40 CFR 51.308(d)(3)(ii) which requires that the State demonstrate 
that it has included in its implementation plan all measures necessary 
to obtain its share of the emissions reductions needed to meet the 
progress goal for the area.
    Response: We agree that Arkansas's point source SO2 
emissions are projected to increase instead of decreasing between 2002 
and 2018, and that the CENRAP modeling indicates that Arkansas's 
contribution to sulfate in class I areas is projected to increase as 
contributions from surrounding states

[[Page 14628]]

are projected to decrease. However, we disagree that this is in 
contradiction with our proposed finding that the Arkansas RH SIP 
satisfies the requirements of 40 CFR 51.308(d)(3)(ii). The full 
reference to 40 CFR 51.308(d)(3)(ii) is the following:

    ``Where other States cause or contribute to impairment in a 
mandatory Class I Federal area, the State must demonstrate that it 
has included in its implementation plan all measures necessary to 
obtain its share of the emissions reductions needed to meet the 
progress goals for the area. If the State has participated in a 
regional planning process, the State must ensure that it has 
included all measures needed to achieve its apportionment of 
emission reduction obligations agreed upon through that process.'' 
\92\
---------------------------------------------------------------------------

    \92\ 40 CFR 51.308(d)(3)(ii).

    A state can meet the requirements under 40 CFR 51.308(d)(3)(ii) if 
when establishing its LTS, the state can demonstrate that it has 
included in its RH SIP all measures necessary to obtain its share of 
the emissions reductions needed to meet the progress goals. This means 
that if a state participates in a regional planning process, the state 
must ensure that the RH SIP includes all agreed upon measures needed to 
achieve its apportionment of emission reduction obligations. Arkansas 
met part of this requirement by participating in a regional planning 
process and consulting with other states that cause or contribute to 
impairment at Arkansas's Class I areas, with the participating states 
arriving at a consensus with regard to each states' apportionment of 
emissions reduction obligations. Arkansas's RH SIP includes the 
regional planning process but those emission reductions agreed to by 
all states in the consultation meetings will not be met by Arkansas 
because the reductions from the BART determinations we are disapproving 
will not be realized. This is consistent with 40 CFR 51.308(d)(3)(ii). 
As explained in our proposed rulemaking on the Arkansas RH SIP, we are 
finding that Arkansas satisfied its consultation requirements when 
establishing its LTS.\93\
---------------------------------------------------------------------------

    \93\ 76 FR 64216.
---------------------------------------------------------------------------

    Comment: The EPA's proposed disapproval of Arkansas's RPGs is not 
consistent with its own guidance, treads on the State's authority under 
the CAA, and disregards the underlying purpose of the visibility 
protection program by criticizing the technical aspect of Arkansas's 
evaluation even though EPA acknowledges that Arkansas's SIP provides 
for a rate of visibility improvement that achieves the national goal 
before the time contemplated by the program itself.
    Response: The EPA disagrees that EPA's disapproval of Arkansas's 
RPGs is not consistent with its own guidance. EPA's RPG Guidance states 
the following with regard to the statutory factors under 40 CFR 
51.308(d)(1)(i)(A):

    ``The regional haze rule requires you to clearly support your 
RPG determination in your SIP submission based on the statutory 
factors.'' \94\
---------------------------------------------------------------------------

    \94\ See EPA's Guidance for Setting Reasonable Progress Goals 
Under the Regional Haze Program (June 1, 2007), Section 2.4.

    As explained in more detail elsewhere in our response to comments, 
even if emission reductions anticipated from implementation of BART and 
other CAA programs during the initial planning period would result in a 
slightly greater rate of improvement in visibility than would be needed 
to attain the URP, the State must still consider the four statutory 
factors in setting its RPGs.
    EPA also disagrees with the commenter's statement that EPA's 
proposed disapproval of Arkansas's RPGs treads on the state's authority 
under the CAA. The CAA requires that in determining reasonable 
progress, states should take into consideration the costs of 
compliance, the time necessary for compliance, and the energy and non-
air quality environmental impacts of compliance, and the remaining 
useful life of any existing source subject to such requirements.\95\ 
Since the State has not taken into consideration these four factors, 
EPA's disapproval of Arkansas's RPGs is in accordance with the CAA. 
While we do recognize that the CENRAP's modeling demonstrates that 
Arkansas is projected to meet the URP for the first implementation 
period ending in 2018 for both of its Class I areas, we emphasize that 
we cannot approve Arkansas's RPGs because in setting its RPGs the State 
did not satisfy the requirements of the CAA Sec.  169A(g)(1), the 
RHR,\96\ and 40 CFR 51.308(d)(1)(i)(A).
---------------------------------------------------------------------------

    \95\ CAA section 169A(g)(1).
    \96\ 64 FR 35731.
---------------------------------------------------------------------------

    Comment: With respect to establishment of RPGs, EPA has provided 
that the BART Rule does not require a definitive dv or percent 
improvement in visibility. All the BART Rule requires for each state is 
a demonstration of improvement of visibility. To that end, ADEQ did 
show in its RH SIP that there was a statistically significant 
improvement to visibility in the Class I areas modeled using the 
presumptive limits through statistical analysis and photochemical 
modeling.
    Response: It appears that the comment may have been referring to 
the RHR rather than the BART Rule, as it is the RHR that establishes 
the RPG requirements. While EPA agrees that the RHR does not require a 
definitive dv or percent improvement in visibility with respect to the 
establishment of RPGs,\97\ we disagree that all the RHR requires in 
terms of RPGs is a demonstration of visibility improvement. The RHR 
requires that the RPGs provide for an improvement in visibility for the 
most impaired days over the period of the implementation plan and 
ensure no degradation in visibility for the least impaired days over 
the same period.\98\ However, the RHR also establishes other analytical 
requirements states must satisfy in establishing their RPGs. Among 
these, is the requirement for states to consider the four statutory 
factors under 40 CFR 51.308(d)(1)(i)(A), which is a requirement that 
Arkansas has not satisfied.
---------------------------------------------------------------------------

    \97\ 64 FR 35731.
    \98\ 64 FR 35734.
---------------------------------------------------------------------------

    Comment: The ADEQ acted consistently with the EPA's RPG Guidance 
when it did not perform a four-factor analysis in establishing 
Arkansas's RPGs. The RPG Guidance provides that if common sense 
dictates that a particular statutory factor cannot be applied to a 
particular source category (i.e. non-point sources), then the state's 
analysis may reflect that, and emissions reductions from such sources 
may still be included in the SIP.
    Response: The section of EPA's RPG Guidance the comment refers to 
states that the guidance is primarily aimed at helping states apply the 
four statutory factors to point sources, and that EPA recognizes that 
even though states must look at all source categories affecting 
visibility when evaluating the four statutory factors, application of 
some of the statutory factors to certain non-point sources may not be 
practical.\99\ The comment appears to imply that this section of EPA's 
RPG Guidance supports the State's decision not to conduct an evaluation 
of the four statutory factors. However, EPA's RPG Guidance does not 
state, or in any way imply, that application of any of the statutory 
factors in considering control measures for point sources is not 
practical. On the contrary, EPA's RPG Guidance clearly states that the 
guidance is mainly aimed

[[Page 14629]]

at helping states apply the four statutory factors to point sources.
---------------------------------------------------------------------------

    \99\ See EPA's Guidance for Setting Reasonable Progress Goals 
Under the Regional Haze Program (June 1, 2007), Section 1.2.
---------------------------------------------------------------------------

    Comment: There is no requirement in the BART Rule for a state to 
adopt control measures that it does not consider necessary or 
reasonable when it can be shown that its RPGs represent a rate of 
progress that it and other affected states have found to be reasonable. 
The EPA's role in evaluating a state's RPGs is to assure that other 
affected states have been consulted and are satisfied that the RPGs are 
appropriate. In fact, Arkansas's Class I areas as well as Missouri's 
Class I areas are on the glidepath and are expected to meet the rate of 
progress goals for the first implementation period ending in 2018.
    Response: While EPA agrees that the BART Rule does not require a 
state to adopt control measures under reasonable progress if the state 
determines that such control measures are not reasonable, EPA notes 
that the state must make the determination of whether those controls 
are reasonable or not through an evaluation of the four statutory 
factors. The RHR states the following:

    ``Today's final rule requires the States to determine the rate 
of progress for remedying existing impairment that is reasonable, 
taking into consideration the statutory factors, and informed by 
input from all stakeholders.'' \100\
---------------------------------------------------------------------------

    \100\ 64 FR 35731.

    Arkansas has not considered the four statutory factors, and 
therefore, cannot make the claim that additional control measures are 
not reasonable. This is especially troublesome in light of the fact 
that there are sources in Arkansas not subject to BART which impair 
visibility by more than 0.5 dv, as explained in more detail in our 
proposed rulemaking. While EPA agrees that one of EPA's roles in 
evaluating a state's RPGs is to assure that other affected states have 
been consulted and agree with the RPGs the state has established,\101\ 
EPA notes that our role is not limited to just that. The RH regulations 
state the following:
---------------------------------------------------------------------------

    \101\ 40 CFR 51.308(d)(1)(iv).

    ``In determining whether the State's goal for visibility 
improvement provides for reasonable progress towards natural 
visibility conditions, the Administrator will evaluate the 
demonstrations developed by the State pursuant to paragraphs d(1)(i) 
and (d)(1)(ii) of this section.'' \102\
---------------------------------------------------------------------------

    \102\ 40 CFR 51.308(d)(1)(iii).

    Among the demonstrations the state is required to develop pursuant 
to 40 CFR 51.308(d)(1)(i) is an evaluation of the four statutory 
factors. As such, EPA's role in evaluating a state's RPGs is not 
limited to ensuring that other affected states have been consulted and 
agree that the state's RPGs are appropriate.
    With regard to the comment that Arkansas Class I areas as well as 
Missouri's Class I areas are on the ``glidepath,'' EPA notes that even 
if a state is projected to meet the URP for its Class I areas during 
the first implementation period ending in 2018, this is not a safe 
harbor from more stringent regulation. The RHR requires states to 
calculate the URP and determine what control measures would be needed 
to achieve this amount of progress during the first implementation 
period and to determine whether those measures are reasonable based on 
an evaluation of the four statutory factors.\103\ The RHR states the 
following:
---------------------------------------------------------------------------

    \103\ 64 FR 35732.

    ``If the State determines that the amount of progress identified 
through the analysis is reasonable based upon the statutory factors, 
the State should identify this amount of progress as its reasonable 
progress goal for the first long-term strategy, unless it determines 
that additional progress beyond this amount is also reasonable. If 
the State determines that additional progress is reasonable based on 
the statutory factors, the State should adopt that amount of 
progress as its goal for the first long-term strategy.'' \104\
---------------------------------------------------------------------------

    \104\ 64 FR 35732.

    As such, being on the ``glidepath'' does not mean a state is 
allowed to forego an evaluation of the four statutory factors when 
establishing its RPGs. Based on an evaluation of the four statutory 
factors, states may determine that RPGs that provide for a greater rate 
of visibility improvement than would be achieved with the URP for the 
first implementation period are reasonable.
    Comment: The EPA's statement in its proposed rulemaking that 
Arkansas's RH SIP fails to ensure adequate reasonable progress toward 
meeting the national visibility goal without Arkansas conducting 
additional analysis is not supported by the record. The EPA admits that 
under Arkansas's RPGs, natural visibility conditions will be obtained 
in 2062 for Caney Creek and 2063 for Upper Buffalo. Based on modeling 
approved by EPA, Arkansas will meet the visibility goals as set out in 
the RHR prior to the target date of 2064. Therefore, the EPA's position 
that Arkansas must undertake additional analysis even though Arkansas's 
proposed RPGs provide a greater rate of improvement in visibility to 
attain URP is incorrect and is an attempt to step on the state's 
authority.
    Response: The EPA notes that the RHR requires states to determine 
what constitutes reasonable progress by, among other things, 
consideration of the four statutory factors. The RHR states that the 
determination of what constitutes reasonable progress can only be made 
once the necessary technical analyses of emissions, air quality, and 
the reasonable progress factors have been conducted.\105\
---------------------------------------------------------------------------

    \105\ 64 FR 35721.
---------------------------------------------------------------------------

    While in our proposed rulemaking we noted that Arkansas calculated 
that under its RPGs, it would attain natural visibility conditions in 
2062 for Caney Creek and 2063 for Upper Buffalo, we would like to 
clarify that such calculation assumes that Arkansas would be able to 
achieve the rate of improvement reflected by the RPGs for the first 
implementation period ending in 2018, and each implementation period 
thereafter. The RHR states the following:

    ``Once a State has adopted a reasonable progress goal and 
determined what progress will be made toward that goal over a 10-
year period, the goal itself is not enforceable. All that is 
`enforceable' is the set of control measures which the State has 
adopted to meet that goal. If the State's strategies have been 
implemented but the State has not met its reasonable progress goal, 
the State could either: (1) Revise its strategies in the SIP for the 
next long-term strategy period to meet its goal, or (2) revise the 
reasonable progress goals for the next implementation period. In 
either case, the State would be required to base its decisions on 
appropriate analyses of the statutory factors included in 40 CFR 
51.308(d)(1)(i)(A) and (B) of the final rule.'' \106\
---------------------------------------------------------------------------

    \106\ 64 FR 35733.

    As such, there is no certainty that the State will achieve its RPGs 
for the first implementation period ending in 2018, let alone for each 
implementation period thereafter. With regard to the comment that the 
modeling approved by EPA shows that Arkansas will meet the visibility 
goals as set out in the RHR prior to the target date of 2064, EPA notes 
that the CENRAP modeled the projected visibility conditions anticipated 
at each Class I area in 2018. The CENRAP modeling is based on emissions 
reductions expected to result from Federal, State, and local control 
programs that are either currently in effect or with mandated future-
year emission reduction schedules that predate 2018. The CENRAP 
modeling itself did not show that Arkansas will meet the visibility 
goals as set out in the RHR prior to 2064. Rather, the rate of 
visibility improvement anticipated by the CENRAP modeling projections 
for 2018, if sustained, will result in a return to natural visibility 
prior to 2064. This assumes that the same level of reduction of 
visibility impairment that is expected

[[Page 14630]]

to occur during the first implementation period ending in 2018 will 
occur during each implementation period until the final implementation 
period ending in 2064. However, there is no guarantee that this will in 
fact occur.
    As explained in our proposed rulemaking on the Arkansas RH SIP, in 
establishing its RPGs, the State is required by CAA Sec.  169A(g)(1) 
and 40 CFR 51.308(d)(1)(i)(A) to consider the costs of compliance, the 
time necessary for compliance, the energy and non-air quality 
environmental impacts of compliance, and the remaining useful life of 
any potentially affected sources, and include a demonstration showing 
how these factors were taken into consideration in selecting the goal. 
An analysis of the four statutory factors is precisely the ``additional 
analysis'' EPA refers to in its proposed rulemaking on the Arkansas RH 
SIP.\107\ The RHR does not exempt states from evaluating the four 
statutory factors if their RPGs provide a greater rate of improvement 
in visibility to attain URP. Since Arkansas has not satisfied this 
requirement, EPA disagrees that our disapproval of Arkansas's RPGs is 
an attempt to step on the state's authority.
---------------------------------------------------------------------------

    \107\ 76 FR 64195.
---------------------------------------------------------------------------

    Comment: The EPA's reliance on disapproving the Arkansas LTS based 
on the disapproval of ADEQ's BART determinations is incorrect and not 
consistent with the RHR. Under the RHR, states must develop a LTS that 
includes emissions limitations, compliance schedules, and other 
measures as necessary to achieve the RPGs for Class I areas within a 
state. Arkansas's LTS complies with the RHR by demonstrating that 
Arkansas will meet the visibility goals as set out in the RHR prior to 
the date of 2064 and the LTS will help Arkansas achieve its RPGs. As 
such, Arkansas should be given the maximum deference in attaining those 
RPGs. In addition, ADEQ's BART determinations are sound and are in 
compliance with the RH program. Thus, the EPA should approve the 
portion of the Arkansas RH SIP pertaining to its LTS.
    Response: With regard to the comment that EPA's reliance on 
disapproving Arkansas's LTS based on the disapproval of some of 
Arkansas's BART determinations is incorrect and inconsistent with the 
RHR, EPA clarifies that the basis for EPA's partial disapproval of the 
State's LTS is that the state did not properly consider emission limits 
and schedules for compliance to include in its LTS, as required 
pursuant to 40 CFR 51.308(d)(3)(v)(C). Since 40 CFR 51.308(d)(3)(v)(C) 
requires that in developing its LTS, Arkansas consider emissions 
limitations and schedules of compliance to achieve the RPGs, the State 
included the BART emission limits it established for its subject to 
BART sources as part of the LTS. As explained in our proposed 
rulemaking, EPA disagrees that all of Arkansas's BART determinations 
are in compliance with the RHR. The BART emission limits established by 
Arkansas are an element of the LTS, and because we are disapproving a 
portion of Arkansas's BART determinations, it follows that the State 
did not properly consider emission limitations and schedules for 
compliance to include in its LTS, as required under 40 CFR 
51.308(d)(3)(v)(C). Therefore, we cannot approve this element of the 
LTS. Furthermore, as raised by another comment, since Arkansas did not 
consider the four statutory factors under 40 CFR 51.308(d)(1)(i)(A) 
when establishing its RPGs, it is not possible to know, at this point, 
whether requiring additional controls for Arkansas source categories 
affecting visibility constitutes reasonable progress. This further 
supports our finding that Arkansas has not properly considered emission 
limitations and schedules for compliance in establishing its LTS, as 
required under 40 CFR 51.308(d)(3)(v)(C).
    The comment suggests that if a state develops a LTS that is 
expected to achieve the state's RPGs and meet the national visibility 
goal prior to 2064, the state will have met the LTS requirements in the 
RHR. While EPA agrees that the RHR requires states to develop a LTS 
that includes emissions limitations, compliance schedules, and other 
measures as necessary to achieve the RPGs established by states having 
mandatory Class I areas,\108\ EPA notes that the RHR establishes 
several requirements a state must satisfy when establishing its 
LTS.\109\ Among these is the requirement for states to consider, at a 
minimum, the seven factors under 40 CFR 51.308(d)(3)(v). As explained 
above, one of the factors states are required to consider is emission 
limitations and schedules for compliance to include in the LTS.\110\ 
Arkansas has not properly considered this factor. Furthermore, as 
already explained above, Arkansas did not establish RPGs in accordance 
with the RHR and CAA requirements. As such, EPA cannot approve those 
RPGs. Therefore, Arkansas has not demonstrated that its LTS includes 
enforceable emissions limitations and compliance schedules, as 
necessary to achieve reasonable progress. EPA cannot fully approve 
Arkansas's LTS.
---------------------------------------------------------------------------

    \108\ 40 CFR 1.308(d)(3).
    \109\ 64 FR 35734.
    \110\ 40 CFR 1.308(d)(3)(v)(C).
---------------------------------------------------------------------------

    Comment: Despite the fact that the CENRAP's modeling for the year 
2018 shows a significant improvement in visibility at Caney Creek and 
Upper Buffalo (3.88 dv and 3.75 dv, respectively), the available 
emissions data that was used to conduct this modeling suggests 
something different. This emissions data shows that SO2 
emissions from EGUs in Arkansas are projected to increase by roughly 
35,000 tons per year (tpy) between 2002 and 2018. While non-EGU point 
source emissions of SO2 in Arkansas are projected to 
decrease by 2018, overall point source emissions of SO2 (EGU 
plus non-EGU emissions) in Arkansas are projected to increase by 
roughly 15,000 tpy. When emissions from all sources of SO2 
in Arkansas are summed together (point sources, onroad sources, and 
area sources), SO2 emissions in 2018 are projected to be 
higher than 2002 levels.
    NOX emissions from non-EGUs are projected to be 25% 
higher in 2018 compared to 2002 levels. Even though NOX 
emissions from non-EGUs are projected to decrease between 2002 and 
2018, overall point source NOX emissions (non-EGUs plus 
EGUs) are projected to increase in 2018 from 2002 levels. When 
emissions from all sources of NOX in Arkansas are summed 
together (point sources, onroad sources, and area sources), 
NOX emissions in 2018 are projected to be lower than 2002 
levels, but most of these emissions reductions are from onroad sources 
in Arkansas. Also, 2018 emissions of PM2.5, PM10, 
and ammonia (NH3) from Arkansas sources were also projected 
to increase somewhat compared to 2002 levels. Considering that sulfates 
are the significant contributor to visibility impairment at both 
Arkansas Class I areas on the majority of the 20% worst days, it is 
difficult to understand how the CENRAP 2018 modeling showed such a 
significant improvement in visibility when SO2 emissions 
from Arkansas are projected to increase between 2002 and 2018.
    EPA also indicated that there is an under-prediction bias in the 
model that must be considered when examining source apportionment 
results for sulfate. Given that the 2018 modeling reflects a low bias 
in the projection of visibility impacts due to sulfates, that there are 
significant projected increases in SO2 emissions from 
Arkansas point sources in 2018, and that the 2018 point source 
emissions from NOX and other visibility impairing pollutants 
are also projected

[[Page 14631]]

to be higher than 2002 emissions, the 2018 CENRAP modeling is 
questionable.
    As discussed by EPA in Appendix A to its TSD for its proposed 
rulemaking on the Arkansas RH SIP, it appears that the bulk of the 
projected visibility improvement in 2018 in Arkansas's Class I areas 
may be based on projected emissions reductions from sources in Texas. 
However, Texas has acknowledged uncertainties in its 2018 emissions 
projections, and that the Texas emissions inventory is based on the 
Integrated Planning Model (IPM) Version 2.19, whereas other planning 
organizations used version 3.0 of the IPM, which EPA has indicated 
provides ``significantly more accurate prediction of future EGU 
operating scenarios and emissions'' (see Exhibit 21). Texas also stated 
that the IPM Version 2.19 used by the CENRAP projected approximately 
14% increase in coal/lignite-fired generating capacity and a 32% 
increase in gas-fired capacity in Texas, whereas the Electric 
Reliability Council of Texas (ERCOT) predicted a greater percentage of 
growth in coal/lignite-fired generating capacity than natural gas-fired 
capacity (see Exhibit 21). Given the uncertainty in Texas' 2018 
emission projections and that the 2018 modeling may under-predict 
visibility impacts from sulfates, Arkansas should not be allowed to 
forego performing an analysis of measures that would enable the state 
to ensure reasonable progress towards reaching natural background 
visibility conditions at the State's Class I areas. EPA must disapprove 
the Arkansas RH SIP for failure to include a four-factor analysis of 
reasonable progress milestones for the State's Class I areas. As part 
of a four-factor analysis of reasonable progress goals, Arkansas should 
evaluate emission control strategies that can be implemented to reduce 
Arkansas's share of visibility-impairing pollution.
    Response: The EPA agrees that SO2 emissions from EGUs in 
Arkansas are projected to increase considerably between 2002 and 2018, 
that overall point source emissions of SO2 (i.e. EGU plus 
non-EGU emissions) in Arkansas are projected to increase by roughly 
15,000 tpy, and that total SO2 emissions in Arkansas (i.e. 
point sources, onroad sources, and area sources combined) are projected 
to increase between 2002 and 2018. We also agree that even though total 
NOX emissions in Arkansas (i.e. point sources, onroad 
sources, and area sources combined) are projected to decrease in 2018 
from 2002 levels, most of these emissions reductions are from onroad 
sources in Arkansas. As discussed in Appendix A of the TSD for our 
proposed action on the Arkansas RH SIP, we agree that the modeling 
demonstrates that most of the projected visibility improvement in 2018 
in Caney Creek appears to be based on projected emissions reductions 
from sources in Texas and that Texas has acknowledged that there are 
uncertainties in its 2018 emissions projections. Consistent with the 
points raised in the comment, we are disapproving Arkansas's RPGs for 
Caney Creek and Upper Buffalo. As discussed in our proposed rulemaking 
and in our response to previous comments, Arkansas must evaluate the 
four statutory factors when establishing its RPGs. As part of its 
evaluation of the four statutory factors Arkansas must determine what 
(if any) level of control is reasonable to require sources in Arkansas 
to comply with to achieve reasonable progress at Arkansas's Class I 
areas.

C. Comments on BART

1. Evaluation of the Most Stringent Level of Control in the BART 
Analysis
    Comment: The EPA pointed out that Entergy White Bluff did not 
evaluate the most stringent level of control achievable in that it did 
not evaluate emission limits lower than the presumptive SO2 
BART emission limit of 0.15 lb/MMBtu for either a wet or a dry 
scrubber, but EPA did not mention that both wet and dry scrubbers can 
achieve greater than the control efficiencies assumed in the White 
Bluff analysis (i.e. greater than 95% control with a wet scrubber, and 
greater than 92% control with a dry scrubber). EPA pointed out that 
SO2 emission rates as low as 0.065 lb/MMBtu have been 
documented with installation of dry scrubbers. EPA recently proposed a 
FIP requiring the installation of dry scrubbers as BART at six coal-
fired EGUs in Oklahoma, to achieve the SO2 BART emission 
limit of 0.06 lb/MMBtu on a 30-day rolling average basis (76 FR 16187-
188, 16193-194). These units burn similar low sulfur coal as that 
primarily burned at the Entergy White Bluff Units 1 and 2. A limit of 
0.06-0.065 lb/MMBtu would reflect 92.2% to 92.8% removal from the 
highest SO2 rate identified by Entergy during the base case 
of 0.83 lb/MMBtu. Therefore, SO2 emission rates much lower 
than 0.15 lb/MMBtu should be achievable with the installation of a wet 
scrubber or a dry scrubber/baghouse at White Bluff Units 1 and 2. Wet 
scrubbers can achieve 98-99% SO2 removal and dry scrubbers 
can achieve 95% SO2 removal (see Exhibits 17, 17A, 17B, 17C, 
and 17D). An October 2008 Sargent & Lundy study of SO2 
control technologies for White Bluff makes clear that dry scrubbers are 
capable of 95% removal efficiency, and wet scrubbers are capable of 95-
99% removal efficiency (see Exhibit 16). This study also indicates that 
the typical Powder River Basin coal SO2 emission rates 
expected from wet scrubbers ranges from 0.03 to 0.10 lb/MMBtu, and for 
dry scrubbers ranges from 0.06 to 0.12 lb/MMBtu. Therefore, EPA should 
require consideration of emission limits more stringent than ADEQ's 
proposed SO2 BART limit of 0.15 lb/MMBtu.
    Response: The EPA agrees that wet scrubbers for control of 
SO2 emissions have been demonstrated to achieve as high as 
98-99% removal efficiency, while dry scrubbers have been demonstrated 
to achieve as high as 95% removal efficiency. SO2 emission 
rates much lower than 0.15 lbs/MMBtu are achievable at Entergy White 
Bluff Units 1 and 2 with the installation of a wet or dry scrubber. 
This is consistent with our proposed rulemaking on the Arkansas RH SIP, 
in which we noted that the 0.15 lb/MMBtu presumptive SO2 
limit the State established for both the bituminous and sub-bituminous 
coal firing scenarios for White Bluff Units 1 and 2 corresponds to 82% 
control removal of the wet scrubber at Unit 1 and 80% control removal 
of the wet scrubber at Unit 2, while such controls are capable of a 
higher control efficiency.\111\ EPA's proposed rulemaking proposed to 
disapprove the State's determination that SO2 BART for White 
Bluff Units 1 and 2 is the presumptive limit of 0.15 lb/MMBtu for both 
the sub-bituminous and bituminous coal firing scenarios, as the State 
is required to evaluate the cost and visibility impact of operating 
controls at the maximum control efficiency achievable (i.e. to achieve 
the most stringent emission limit capable of being achieved by those 
controls).\112\,\113\
---------------------------------------------------------------------------

    \111\ 76 FR 64206.
    \112\ 64 FR 35740.
    \113\ 76 FR 64206.
---------------------------------------------------------------------------

    Comment: A study conducted by Babcock & Wilcox at tangentially-
fired units burning sub-bituminous Powder River Basin coal showed 
NOX emission rates with ultra low NOX burners and 
overfire air that were generally less than 0.13 lb/MMBtu (see Exhibit 
17F). The proposed NOX limits for White Bluff Units 1 and 2 
of 0.15 lb/MMBtu when burning sub-bituminous coal and 0.28 lb/MMBtu 
when burning bituminous coal do not reflect the capability of the state 
of the art low NOX burners and overfire air. Also, since the 
White Bluff Units 1 and 2 burn primarily sub-bituminous coal, EPA's 
presumptive BART limit for sub-bituminous coal

[[Page 14632]]

(and not for bituminous coal) should be evaluated. The BART Guidelines 
do not provide for prorating the presumptive BART limits based on the 
percentages of each coal burned. Presumptive limits should be defined 
by the coal type predominantly burned by the White Bluff units and BART 
must be based on the coal the units have historically burned, not on 
the type of coal that might be used in the future.
    Response: The EPA agrees that the NOX limits adopted by 
the State of 0.15 lb/MMBtu when burning sub-bituminous coal and 0.28 
lb/MMBtu when burning bituminous coal for White Bluff Units 1 and 2 do 
not reflect the capability of the state of the art low NOX 
burners and overfire air.
    In addition, the BART Rule and the BART Guidelines do not specify 
whether a state can make separate BART determinations for each type of 
fuel burned by a given source. This should not be interpreted to mean 
that a state is not allowed to make separate BART determinations for 
each fuel type burned by a given source. The CAA and BART Rule give 
states broad authority in making BART determinations. Accordingly, 
States may determine it is appropriate to make BART determinations for 
each type of fuel burned by a given source. EPA acknowledges that the 
BART Guidelines do not specifically mention whether or not states can 
prorate the presumptive BART limits based on the percentages of each 
coal burned. However, if a source has a history of burning more than 
one type of fuel, then the BART determination must either be based on 
the fuel resulting in the greatest amount of emissions or the State 
must consider BART for each fuel type.
    Comment: BART is not the maximum feasible technology but only the 
technology that is appropriate as determined by the state in weighing 
the public interest factors. EPA is incorrect in its assertion that the 
BART Guidelines require consideration of the most stringent control 
technology in the BART analysis. The EPA is going beyond the scope of 
the CAA by proposing that BART analysis requires identification and 
evaluation of the maximum control technology available when the state 
conducts BART evaluations.
    Response: The EPA agrees that BART is not defined as the ``maximum 
feasible technology.'' However, EPA disagrees that EPA is going beyond 
the scope of the CAA by stating that states must evaluate the most 
stringent controls available in their BART evaluations. The BART 
Guidelines explicitly require consideration of the most stringent 
control technology in the BART analysis. The CAA states the following:

    ``[I]n determining best available retrofit technology the State 
(or the Administrator in determining emission limitations which 
reflect such technology) shall take into consideration the costs of 
compliance, the energy and non-air quality environmental impacts of 
compliance, any existing pollution control technology in use at the 
source, the remaining useful life of the source, and the degree of 
improvement in visibility which may reasonably be anticipated to 
result from the use of such technology * * *'' \114\
---------------------------------------------------------------------------

    \114\ CAA section 169A(g)(2).

    In accordance with the CAA, EPA promulgated the BART Rule and the 
BART Guidelines to clarify the requirements of the RHR's BART 
---------------------------------------------------------------------------
provisions. The BART Guidelines provide the following:

``In identifying ``all'' options, you must identify the most 
stringent option and a reasonable set of options for analysis that 
reflects a comprehensive list of available technologies. It is not 
necessary to list all permutations of available control levels that 
exist for a given technology-the list is complete if it includes the 
maximum level of control each technology is capable of achieving.'' 
\115\
---------------------------------------------------------------------------

    \115\ Appendix Y to Part 41, section IV.D.

    Furthermore, the RH regulations define BART as the best system of 
continuous emission control technology available and associated 
emission reductions achievable, as determined through an evaluation of 
the five statutory factors.\116\ As explained in our proposed 
rulemaking on the Arkansas RH SIP, the RHR states that since recent 
retrofits at existing sources provide a good indication of the current 
``best system'' for controlling emissions, these controls must be 
considered in the BART analysis.117 118 EPA's proposed 
rulemaking also explains that the RHR provides that in establishing 
source specific BART emission limits, a state's BART analysis must 
identify and consider the maximum level of emission reduction that has 
been achieved in other recent retrofits at existing sources in the 
source category.119 120
---------------------------------------------------------------------------

    \116\ 40 CFR 51.308(e)(1)(ii)(A).
    \117\ 64 FR 35740.
    \118\ 76 FR 64202.
    \119\ 64 FR 35740.
    \120\ 76 FR 64202.
---------------------------------------------------------------------------

2. Evaluation of Post-Combustion Controls in the BART Analysis
    Comment: We agree with EPA's proposal that the White Bluff Units 1 
and 2 BART analysis for NOX in the Arkansas RH SIP only 
evaluated options to comply with the presumptive BART limits and the 
company failed to evaluate add-on NOX controls such as SCR 
and SNCR. NOX emission limits as low as 0.05 lb/MMBtu, 
achieved by the installation of SCR, have been promulgated as BART 
limits for EGUs such as the San Juan power plant in New Mexico (76 FR 
52390, 52439). SCR along with combustion controls are routinely 
required as BACT today for proposed new coal-fired power plants. SCR 
along with combustion controls have also been required as BART or to 
meet RH progress goals at several coal fired power plants, including 
the Boswell Energy Center Unit 3 and the Alan S. King Unit 1 facility 
in Minnesota (see Minnesota Air Pollution Control Agency revised draft 
RH SIP, July 2009); Naughton Unit 3 and Jim Bridger Units 3 and 4 in 
Wyoming (see Wyoming draft RH SIP, January 2011); San Juan Units 1-4 
(see 76 FR 52388); Four Corners Units 1-5 (See 75 FR 64230); and Big 
Stone Unit 1 (see EPA's November 29, 2011 proposed rulemaking on the 
South Dakota RH SIP). Installation of SCR along with combustion 
controls has been found to be cost-effective both in BART and BACT 
determinations, with costs ranging from approximately $4200/ton 
NOX removed all the way up to $21,000/ton NOX 
removed (see Exhibit 17, 17H, 17I, 17J, and 17K). According to data 
compiled by the National Parks Service, the cost effectiveness of SCR 
controls at units required to install such controls to meet RH 
requirements has ranged from $2,200 to $4,300/ton NOX 
removed (see Exhibit 19). White Bluff would greatly reduce 
NOX emissions beyond that achieved by the combustion 
controls proposed as BART if it were to install SCRs as BART at each 
unit. If SCR had been evaluated as BART at White Bluff Units 1 and 2, 
NOX emissions would have been 78% lower when the units burn 
sub-bituminous coal and 82% lower when the units burn bituminous coal. 
Based on testimony before the Arkansas Public Service Commission, 
Entergy appears to be planning to install SCR at both units at some 
point in the near future (see Exhibit 17L). Entergy's NOX 
BART analysis for White Bluff cannot be considered complete without an 
evaluation of combustion controls plus SCR.
    Response: The EPA agrees that installation and operation of SCR as 
BART could potentially result in the reduction of NOX 
emissions beyond that achieved by operation of the combustion controls 
proposed by the State as BART for White Bluff Units 1 and 2. EPA also 
agrees that the State must evaluate SCR controls when it evaluates what 
is BART for Entergy

[[Page 14633]]

White Bluff Units 1 and 2. As explained elsewhere in this final 
rulemaking, we are finalizing our proposed disapproval of the State's 
NOX BART determination (bituminous and sub-bituminous coal 
firing scenarios) for White Bluff Units 1 and 2.
    Comment: Since EPA explicitly did not evaluate post combustion 
controls in establishing presumptive limits for EGUs that burn coal and 
do not have existing post-combustion controls for NOX in the 
BART Guidelines, post combustion controls should not be required to be 
evaluated as part of Arkansas's NOX BART evaluations of 
Entergy's White Bluff facility. In addition, since EPA explicitly did 
not evaluate post combustion technology when establishing presumptive 
limits for boilers other than cyclone units in the BART Guidelines, 
post combustion controls should not be required to be evaluated as part 
of the Arkansas BART evaluations for Lake Catherine facility.
    Response: The EPA agrees that we did not evaluate post-combustion 
controls in providing NOX presumptive emission limits for 
EGUs that burn coal and have no existing post-combustion controls. The 
EPA also points out the BART Guidelines did not provide presumptive 
limits for oil-fired units such as Entergy Lake Catherine Unit 4. This 
does not mean that Arkansas may forego an evaluation of post-combustion 
controls in its NOX BART analyses for Entergy White Bluff 
Units 1 and 2 and Lake Catherine Unit 4. As stated in our proposed 
rulemaking on the Arkansas RH SIP, the purpose of the presumptive 
limits in the BART Guidelines was to identify controls that the Agency 
considered to be generally cost-effective across all affected 
units.\121\ Because EPA's extensive analysis found that these controls 
are generally cost-effective across all affected units and were 
anticipated to result in a substantial degree of visibility 
improvement, EPA concluded that such affected units should at least 
meet the presumptive limits unless the state finds that a more or less 
stringent emission limit is BART based on a consideration of the five 
statutory factors. EPA's intent was for these generally cost-effective 
controls to be used in the State's BART analysis considering the five 
factors specified in CAA section 169A(g)(2), and considering the level 
of control that is currently achievable at the time that the BART 
analysis is being conducted.
---------------------------------------------------------------------------

    \121\ 76 FR 64201.
---------------------------------------------------------------------------

    Further, in the BART Rule, EPA justified its decision not to 
establish presumptive NOX limits based on the use of SCR for 
units other than cyclone units, stating the following:

    ``For other units, we are not establishing presumptive limits 
based on the installation of SCR. Although States may in specific 
cases find that the use of SCR is appropriate, we have not 
determined that SCR is generally cost-effective for BART across unit 
types.'' \122\
---------------------------------------------------------------------------

    \122\ 70 FR 39136.

    As such, in the BART Guidelines, EPA simply concluded that it could 
not reach a generalized conclusion as to the appropriateness of more 
stringent controls (i.e. post-combustion controls) for coal-fired EGUs 
without existing post-combustion controls. Similarly, EPA concluded 
that it could not reach a generalized conclusion as to the 
appropriateness of providing presumptive limits based on the 
installation of SCR (or even combustion controls for that matter) for 
oil-fired units. This does not mean that states should not evaluate 
post-combustion NOX controls at affected sources. As 
explained elsewhere in this final rulemaking, in response to comments 
on the proposed BART Guidelines that the presumptive SO2 EGU 
limits should be more stringent, EPA justified its decision to not 
provide more stringent presumptive emission limits by explaining that 
after considering the five statutory factors, States may find that a 
more or less stringent emission limit is BART [emphasis added].\123\ 
Similar statements are made elsewhere in the BART Rule.
---------------------------------------------------------------------------

    \123\ 70 FR 39132.
---------------------------------------------------------------------------

    Furthermore, the RH regulations define BART as the best system of 
continuous emission control technology available and associated 
emission reductions achievable, as determined through an evaluation of 
the five statutory factors.\124\ As explained in our proposed 
rulemaking on the Arkansas RH SIP, the RHR states that since recent 
retrofits at existing sources provide a good indication of the current 
``best system'' for controlling emissions, these controls must be 
considered in the BART analysis.125 126 EPA's proposed 
rulemaking also explains that the RHR provides that in establishing 
source specific BART emission limits, a state's BART analysis must 
identify and consider the maximum level of emission reduction that has 
been achieved in other recent retrofits at existing sources in the 
source category.127 128 In most cases, the maximum level of 
emission reduction is achieved through the installation and operation 
of post-combustion controls. Therefore, the State should evaluate post-
combustion controls in its BART analysis for Entergy White Bluff Units 
1 and 2.
---------------------------------------------------------------------------

    \124\ 40 CFR 51.308(e)(1)(ii)(A).
    \125\ 64 FR 35740.
    \126\ 76 FR 64202.
    \127\ 64 FR 35740.
    \128\ 76 FR 64202.
---------------------------------------------------------------------------

    Comment: The BART Guidelines indicate that States should only 
consider the installation of current combustion control technology on 
oil and gas-fired units. Therefore, EPA cannot disapprove BART 
determinations on the basis that post combustion control technology was 
not evaluated for Entergy's Lake Catherine Unit 4.
    Response: The EPA disagrees that the BART Guidelines indicate that 
States should only consider the installation of current combustion 
control technology on oil and gas-fired units. The BART Guidelines 
state the following:

    ``For oil-fired and gas-fired EGUs larger than 200 MW, we 
believe that installation of current combustion control technology 
to control NOX is generally highly cost-effective and 
should be considered in your determination of BART for these 
sources.'' \129\
---------------------------------------------------------------------------

    \129\ Appendix Y to Part 51, section IV.E.4.

    The context of the above statement is with regard to whether EPA 
believed a presumptive emissions limit is appropriate for gas fired and 
fuel oil fired EGUs. It was not intended to limit the consideration for 
BART for these sources to combustion controls only. The BART Guidelines 
should not be interpreted to mean that states should not consider 
NOX post-combustion controls in their BART analyses for gas 
fired and oil fired units. The RH regulations define BART as the best 
system of continuous emission control technology available and 
associated emission reductions achievable, as determined through an 
evaluation of the five statutory factors.\130\ As explained in our 
proposed rulemaking on the Arkansas RH SIP, the RHR states that since 
recent retrofits at existing sources provide a good indication of the 
current ``best system'' for controlling emissions, these controls must 
be considered in the BART analysis.131 132 EPA's proposed 
rulemaking also explains that the RHR provides that in establishing 
source specific BART emission limits, a state's BART analysis should 
identify and consider the maximum level of emission reduction that has 
been achieved in other recent retrofits at existing sources in the 
source category.133 134 In most cases, the maximum level of 
emission reduction is achieved through the

[[Page 14634]]

installation and operation of post-combustion controls. Therefore, the 
State must evaluate post-combustion control technology in its BART 
analysis for Entergy Lake Catherine Unit 4.
---------------------------------------------------------------------------

    \130\ 40 CFR 51.308(e)(1)(ii)(A).
    \131\ 64 FR 35740.
    \132\ 76 FR 64202.
    \133\ 64 FR 35740.
    \134\ 76 FR 64202.
---------------------------------------------------------------------------

    Comment: The EPA cannot disapprove the NOX BART 
determinations for the Domtar Ashdown Mill Power Boilers No. 1 and 2 
for not evaluating SNCR. While SNCR has been installed on several 
industrial boilers similar to Domtar's Boilers, at the time that the 
BART evaluation was conducted, SNCR was not available. Even if you 
considered SNCR and a 50% reduction in emissions (the upper level of 
control expected with SNCR) less than 10 days of impacts greater than 
0.5 dv would be eliminated. Thus, the cost of SNCR is not appropriate, 
especially considering Arkansas is already achieving progress toward 
the overall goal of the RH program.
    Response: The BART Guidelines provide the following:

    ``In order to provide certainty in the process, all technologies 
should be considered if available before the close of the State's 
public comment period. You need not consider technologies that 
become available after this date. As part of your analysis, you 
should consider any technologies brought to your attention in public 
comments. If you disagree with public comments asserting that the 
technology is available, you should provide an explanation for the 
public record as to the basis for your conclusion.'' \135\
---------------------------------------------------------------------------

    \135\ Appendix Y to Part 51, section IV.D.2.

    As pointed out in our proposed rulemaking on the Arkansas RH SIP, 
SNCR was available for industrial boilers similar to Domtar's boilers 
before the close of the State's public comment period.\136\ As 
documented by Arkansas in Appendix 2.1 of its RH SIP, EPA provided 
comments to Arkansas on this matter on May 1, 2007. This was far in 
advance of the end of the State's public comment period. As documented 
in Appendix 2.1 of the Arkansas RH SIP, the State did not provide any 
form of response to EPA's comment, nor did the State evaluate operation 
and installation of SNCR at Domtar Ashdown Mill Power Boilers No. 1 and 
2.
---------------------------------------------------------------------------

    \136\ 76 FR 64209.
---------------------------------------------------------------------------

    Since the State did not conduct modeling to evaluate the visibility 
impact of operation of SNCR at Domtar Power Boilers No. 1 and 2, it is 
not clear how one could reach a conclusion that SNCR would result in 
the elimination of less than 10 days of impacts greater than 0.5 dv. 
Furthermore, the RHR and BART Guidelines require states to consider all 
five statutory factors, and not just the visibility impact resulting 
from operation of SNCR. The BART Rule states the following:

    ``[T]he degree of improvement in visibility which may reasonably 
be anticipated to result from the use of [BART]'' is only one of 
five criteria that the State must consider together in making a BART 
determination.'' \137\
---------------------------------------------------------------------------

    \137\ 70 FR 39123.

    A proper evaluation of SNCR, through a consideration of the five 
statutory factors, may demonstrate that installation and operation of 
SNCR at Domtar Power Boilers 1 and 2 is cost-effective. As such, EPA 
cannot approve the State's NOX BART determinations for the 
Domtar Power Boilers No. 1 and 2.
    Comment: The EPA is incorrect in stating that not all technically 
feasible options were considered and visibility impacts considered for 
the NOX BART determination for Domtar. Methane De-
NOX (MdN) is the only control technology deemed technically 
feasible for which modeling was not completed. The technical capability 
of MdN is highly questionable. There is no reason to complete a 
modeling analysis for this option because it was cost prohibitive 
regardless of what visibility improvement may be gained from its use. 
Because of this, the decision was made to forgo the modeling. Such a 
decision is within ADEQ's discretionary authority to weigh the BART 
factors as they feel appropriate as spelled out in the BART Guidelines. 
This decision is reasonable since ADEQ is already achieving better than 
necessary progress towards attaining its visibility goals.
    Response: The EPA stands by the statement made in its proposed 
rulemaking on the Arkansas RH SIP that not all technically feasible 
options were considered for the NOX BART determination for 
Domtar Power Boilers 1 and 2. As explained in our proposed rulemaking 
and elsewhere in our response to comments, Arkansas did not evaluate 
SNCR controls even though such NOX control is technically 
feasible, having been demonstrated at industrial boilers similar to 
Domtar Power Boilers No. 1 and 2 well in advance of the end of the 
State's public comment period for the Arkansas RH SIP.
    EPA also stands by the statement made in its proposed rulemaking on 
the Arkansas RH SIP that the State did not evaluate the visibility 
impact of all technically feasible options. The preamble to the RHR 
states the following:

    ``We agree with commenters who asserted that the method for 
assessing BART controls for existing sources should consider all of 
the statutory factors.'' \138\
---------------------------------------------------------------------------

    \138\ 70 FR 39131.

    The BART Guidelines also provide the following with regard to the 
---------------------------------------------------------------------------
selection of BART:

    ``You have discretion to determine the order in which you should 
evaluate control options for BART. Whatever the order in which you 
choose to evaluate options, you should always (1) display the 
options evaluated; (2) identify the average and incremental costs of 
each option; (3) consider the energy and non-air quality 
environmental impacts of each option; (4) consider the remaining 
useful life; and (5) consider the modeled visibility impacts.'' 
\139\
---------------------------------------------------------------------------

    \139\ Appendix Y to Part 51, section IV.E.2.

    Therefore, in their BART evaluations, States must consider the 
visibility impact of a control option before eliminating it. In 
particular, for Domtar Power Boiler No. 1, for which the State 
determined that NOX BART is no additional controls 
(resulting in no emissions reductions or visibility improvement beyond 
baseline levels), an evaluation of all five statutory factors is 
necessary before the State can make the determination that no retrofit 
controls are available for Domtar Power Boiler No. 1.
    The EPA disagrees with the comment that the decision to forego 
modeling the visibility impacts of Methane De-NOX (the only 
technically feasible control option the State identified for Domtar 
Power Boiler 1) is reasonable since ADEQ is already achieving better 
than necessary progress towards attaining its visibility goals. EPA 
would like to clarify that the State is not already achieving better 
than necessary progress towards attaining its visibility goals, as the 
commenter's statement is based on modeling projections based on 
emissions reductions resulting from BART and the implementation of 
other CAA requirements, and many of these emissions reductions have yet 
to take place. Furthermore, as explained in more detail in our proposed 
rulemaking on the Arkansas RH SIP and elsewhere in our response to 
comments, EPA is disapproving the State's RPGs because the State did 
not evaluate the four statutory factors under 40 CFR 
51.308(d)(1)(i)(A). Therefore, the claim that Arkansas is already 
achieving better than necessary progress towards attaining its 
visibility goals cannot be made.
    Comment: In addition to reducing visibility impairing regional 
haze, SCR systems can oxidize elemental mercury, making it easier to 
capture downstream in wet flue gas desulfurization (FGD) systems or PM 
collection devices.

[[Page 14635]]

Industry improvements in SCR technology that would enhance mercury 
oxidation for all coal types are currently being developed. Significant 
mercury reductions would be a likely co-benefit if an SCR is coupled 
with a baghouse designed for state-of-the-art PM control.
    Response: While EPA agrees that SCR technology coupled with a 
baghouse may result in significant reductions in mercury emissions, EPA 
notes that mercury is not considered a visibility impairing pollutant. 
As such, the control of mercury emissions is outside the scope of the 
RHR. However, if in evaluating control technologies for a BART 
pollutant for a given source, a state finds that two or more 
technologies (or combination of technologies) would have similar 
visibility benefits, the state may justify selection of one of the 
technologies on the basis of its non-air quality environmental 
benefits. For example, a state may justify selection of SCR technology 
coupled with a baghouse to control NOX emissions over a 
different control option on the basis that SCR coupled with a baghouse 
would result in less mercury emissions going into the soil or a nearby 
body of water. That being said, as explained in our proposed rulemaking 
on the Arkansas RH SIP and elsewhere in our response to comments, 
Arkansas must evaluate NOX post-combustion controls (i.e. 
SCR and SNCR) in its BART analyses for subject to BART sources.
    Comment: SCR would remove up to 3,832 tpy NOX per unit 
at Entergy White Bluff beyond what the combustion controls currently 
proposed to meet BART would remove. Visibility in the Region's Class I 
areas would further be improved by the NOX emissions 
reductions achievable with combustion controls plus SCR at White Bluff 
Units 1 and 2, especially since, as EPA stated in its proposed 
rulemaking, a ``considerable portion'' of the visibility impairment in 
the Class I areas of Arkansas and Missouri is due to NOX 
emissions (76 FR 64207). According to EPA's AirData Web site, in 2002, 
the most recent year of emissions data in the AirData system, White 
Bluff was the largest industrial source of NOX emissions in 
the state. Therefore, it is necessary that a complete and proper 
evaluation of SCR and combustion controls be conducted to determine 
BART for White Bluff Units 1 and 2.
    Response: Consistent with our proposed rulemaking on the Arkansas 
RH SIP and other responses to other comments, EPA agrees that the State 
must conduct a BART analysis that properly evaluates both combustion 
and post-combustion controls at Entergy White Bluff Units 1 and 2.
3. Comments on the State's PM BART Emission Limits We Proposed To 
Approve
    Comment: BART is based on a five-factor analysis, and the 
requirement for a five-factor analysis stems from statutory and 
regulatory requirements regarding how BART is to be determined (see 40 
CFR 51.308(e)(1)(ii)(A) and section 169A(g) of the CAA, 42 U.S.C. 
7491(g)). A proper evaluation of BART for White Bluff Units 1 and 2 and 
Flint Creek Boiler No. 1 would have shown that each sources' existing 
PM limit does not reflect PM BART for the sources.
    Response: In our review of the Arkansas RH SIP, we evaluated the 
determination by ADEQ that no additional PM controls were required at 
the AEP Flint Creek Boiler No. 1 or the Entergy White Bluff Units 1 and 
2. For Flint Creek Boiler No. 1, ADEQ's determination was based on the 
pre-control modeling performed by ADEQ and on AEP SWEPCO's statement 
that the PM visibility modeling did not ``trip the BART impact 
threshold.'' We reviewed the pre-control modeling performed by ADEQ 
using the 24-hr actual maximum emissions from the baseline period. The 
modeling results in Appendix 9.2B of the Arkansas RH SIP and presented 
in Table 7-6 of Appendix A of the TSD,\140\ indicate that PM 
contributes less than 0.5% of the total visibility impacts from Flint 
Creek Boiler No. 1 at all nearby Class I areas with the exception of 
Upper Buffalo. PM contributions to visibility impacts at Upper Buffalo 
from Flint Creek are less than 2% of the total visibility impairment at 
this Class I area. On the most impacted day at Upper Buffalo, modeling 
the 24-hr actual maximum emissions demonstrates that PM contributes 
only 0.07 dv of the total 3.781 dv modeled visibility impact from the 
source. Clearly, the most effective controls to address visibility 
impairment from the source are those that would reduce emissions of 
visibility impairing pollutants other than direct emissions of PM.
---------------------------------------------------------------------------

    \140\ These documents can be found in the docket associated with 
our final rulemaking.
---------------------------------------------------------------------------

    For White Bluff Units 1 and 2, we reviewed the data submitted by 
ADEQ, including pre-control modeling in Appendix 9.2B of the Arkansas 
RH SIP, to evaluate ADEQ and White Bluff's determination that the 
majority of visibility-causing emissions are due to emissions of 
NOX and SO2, and that no additional PM controls 
are warranted. The modeling results in Appendix 9.2B of the Arkansas RH 
SIP and presented in Table 7-7 of Appendix A of the TSD for our 
proposed rulemaking, indicate that PM contributes less than 0.4% of the 
total visibility impacts at all nearby Class I areas. On the most 
impacted day at Caney Creek, modeling the 24-hr actual maximum 
emissions demonstrates that PM contributes only 0.03 dv of the more 
than 8 dv modeled visibility impact from the White Bluff Units 1 and 2. 
Clearly, the majority of visibility-causing emissions are due to 
emissions of NOX and SO2 and the most effective 
controls to address visibility impairment from the units are those that 
would reduce emissions of NOX and SO2 rather than 
direct emissions of PM.
    As explained in our proposed rulemaking, in our evaluation for PM 
BART for these sources, we found that the visibility impact due to PM 
emissions alone is so minimal such that any additional PM controls 
could only result in very minimal visibility benefit that could not 
justify the cost of any upgrades and/or operational costs needed to 
operate the existing controls to achieve a more stringent emission 
limit. This is in keeping with the BART Rule, which provides the 
following:

    ``Consistent with the CAA and the implementing regulations, 
States can adopt a more streamlined approach to making BART 
determinations where appropriate. Although BART determinations are 
based on the totality of circumstances in a given situation, such as 
the distance of the source from a Class I area, the type and amount 
of pollutant at issue, and the availability and cost of controls, it 
is clear that in some situations, one or more factors will clearly 
suggest an outcome. Thus, for example, a State need not undertake an 
exhaustive analysis of a source's impact on visibility resulting 
from relatively minor emissions of a pollutant where it is clear 
that controls would be costly and any improvements in visibility 
resulting from reductions in emissions of that pollutant would be 
negligible. In a scenario, for example, where a source emits 
thousands of tons of SO2 but less than one hundred tons 
of NOX, the State could easily conclude that requiring 
expensive controls to reduce NOX would not be 
appropriate.'' \141\
---------------------------------------------------------------------------

    \141\ 70 FR 39116.

    Therefore, we are approving the State's determination that PM BART 
for Flint Creek Boiler No. 1 and White Bluff Units 1 and 2 is the 
existing PM emission limit (i.e. no additional controls).
    Comment: The EPA should not partially approve the State's BART 
determination for a given source for some pollutants and disapprove the 
BART determination for other pollutants without also concurrently 
promulgating BART requirements for the pollutants that have been 
disapproved. EPA should not approve

[[Page 14636]]

the PM BART controls for the AEP Flint Creek Power Plant, the Entergy 
White Bluff Power Plant, and the No. 1 Power Boiler of the Domtar 
Ashdown Mill before knowing what the SO2 and NOX 
BART controls will be because the SO2 or NOX 
controls determined to be BART may increase PM emissions or otherwise 
affect the PM BART determination.
    Response: You cannot infer from the RHR that the disapproval of the 
BART determination for one pollutant at a given source requires 
disapproval of BART determinations for other pollutants at the same 
source. Each BART analysis for an individual visibility impairing 
pollutant is separate. As such, disapproval of the SO2 or 
NOX BART determination does not affect the PM BART 
determination even though SO2 and NOX are 
precursors to PM. This is because when the BART determination is 
conducted for PM, it is analyzed without taking in account whether BART 
controls for SO2 or NOX are being adopted. As 
such, EPA may take action on the BART determinations for 
NOX, SO2, and PM for a given source in separate 
rulemaking actions. In addition, EPA may approve the BART determination 
for one pollutant for a given source while disapproving the BART 
determination for one or more pollutants at the same source. Therefore, 
EPA disagrees with the commenter that it cannot approve the PM BART 
determinations for the Flint Creek Boiler No. 1, the White Bluff Units 
1 and 2, and the Domtar Ashdown Mill Power Boiler No. 1, and disapprove 
the SO2 and NOX BART determinations for these 
sources without promulgating SO2 and NOX BART 
determinations for these sources in the context of a FIP.
    As explained in our proposed rulemaking and elsewhere in this final 
rulemaking, our disapproval begins a two year period after which if 
Arkansas has not provided a new SIP revision and EPA has approved that 
SIP revision correcting the deficiencies, EPA must promulgate a FIP. If 
in conducting the BART analyses for NOX and SO2, 
Arkansas, or EPA in the context of a FIP, determines that direct 
emissions of PM will increase because of the implementation of certain 
control technologies, the BART PM limit can be re-evaluated at that 
time and balanced against the potential visibility improvements from 
the reductions of the other pollutants.
    Comment: In the testimony for a permit proceeding, Entergy's 
primary contractor for engineering and procurement of its BART controls 
showed that PM emission rates much lower than 0.1 lb/MMBtu could be met 
with either a wet scrubber or with a dry scrubber and a baghouse 
installed at the Entergy White Bluff Units 1 and 2 (see Exhibits 12 and 
16). Entergy's contractor indicated that if a dry scrubber and baghouse 
were installed at White Bluff Units 1 and 2, the baghouse would be 
designed to lower the PM emissions to 0.012 lb/MMBtu, giving an 
advantage of the dry scrubber over the wet scrubber. Since the 
selection of the SO2 scrubber (wet vs. dry) will have an 
impact on the PM emissions rate that will be achievable at the White 
Bluff units, EPA should not take any action on PM BART for White Bluff 
until the SO2 controls to meet BART are known.
    Response: The comment points out that in the testimony for a permit 
proceeding before the Arkansas Public Service Commission,\142\ 
Entergy's contractor indicated that if a dry scrubber and baghouse are 
installed at the Entergy White Bluff Units 1 and 2, the baghouse would 
be designed to lower the PM emissions to an emission rate of 0.012 lb/
MMBtu.\143\ However, it has also been brought to EPA's attention that 
Entergy White Bluff has since canceled the proceeding before the 
Arkansas Public Service Commission to obtain a declaratory order 
approving the installation of those controls. Furthermore, the State 
has not submitted to EPA a revision to the RH SIP EPA received on 
September 23, 2008, August 3, 2010, and supplemented on September 7, 
2011. As far as EPA is aware, the State has not adopted revisions to 
the Arkansas RH SIP with respect to BART for SO2 for Entergy 
White Bluff Units 1 and 2 based on the proceeding before the Arkansas 
Public Service Commission. Therefore, what is before EPA is the 
Arkansas RH SIP submitted to EPA on September 23, 2008 August 3, 2010, 
and supplemented on September 7, 2011, which does not include 
installation of a dry scrubber and baghouse for control of 
SO2 at White Bluff Units 1 and 2. As explained elsewhere in 
our response to comments, the RHR states that the BART determinations 
are made on a individual pollutant specific basis and this analysis is 
separate from the BART determinations for other pollutants at the same 
source. Therefore, EPA disagrees that it should not take action on PM 
BART for White Bluff Units 1 and 2 until the SO2 controls to 
meet BART are known.
---------------------------------------------------------------------------

    \142\ The Arkansas Public Service Commission is an appointed 
executive board in the Arkansas state government. The commission is 
responsible for regulating the rates and services of Arkansas's 
electricity, natural gas, water, phone, and pipeline safety 
utilities.
    \143\ See Exhibit 12 to Sierra Club's comment letter to EPA, 
found in the docket for this rulemaking action.
---------------------------------------------------------------------------

    Our approval of the limit for direct PM emissions was based on the 
extremely low modeled visibility impact from these emissions. While 
reductions in PM may occur from future controls necessary to meet 
SO2 BART, these PM reductions are not necessary to meet BART 
for PM.
    Comment: The EPA's BART Guidelines specify that BART should be 
evaluated and defined for both PM10 and PM2.5 
(see 40 CFR part 51, appendix Y, section IV.A.). However, with the 
exception of the oil-firing scenario for Lake Catherine Unit 4, ADEQ 
did not adopt BART limits for PM2.5, yet EPA did not 
identify this as a deficiency. EPA must disapprove the PM/
PM10 BART limits in the Arkansas RH SIP along with 
disapproving the RH SIP for the lack of BART limits for 
PM2.5.
    Response: The BART Guidelines do not specify that states must make 
BART determinations for PM2.5. The BART Guidelines provide 
the following:

    ``You must look at SO2, NOX, and direct 
particulate matter (PM) emissions in determining whether sources 
cause or contribute to visibility impairment, including both 
PM10 and PM2.5.'' \144\
---------------------------------------------------------------------------

    \144\ Appendix Y to Part 51, section III.A.2.

    This language in the BART Guidelines was meant to clarify that when 
a state is making a BART determination as to whether a source is 
subject to BART, the modeling evaluation to determine the source's 
impact on visibility has to account for both PM10 and 
PM2.5 emissions. There are several instances in which we 
state in both the preamble to the RHR, and in the BART Guidelines that 
PM10 may be used as indicator for PM2.5 in 
determining whether a source is subject to BART. However, neither the 
RHR nor the BART Guideline specify that states must set separate BART 
limits for PM2.5. We have concluded that Arkansas's PM BART 
determinations for the natural gas firing scenario for Entergy Lake 
Catherine Unit 4; for the bituminous and sub-bituminous coal firing 
scenarios for Entergy White Bluff Units 1 and 2; for the AEP Flint 
Creek Boiler No. 1; and for the Domtar Ashdown Mill Power Boiler No. 1 
are reasonable.
    Comment: The existing PM limit of 0.1 lbs/MMBtu in the AEP Flint 
Creek Title V permit, which EPA proposed to approve as BART for PM, is 
based on EPA's New Source Performance Standards (NSPS) for Fossil-Fuel 
Fired Steam Generators that commenced construction after August 17, 
1971 (40 CFR part 60, subpart D, Sec.  60.42(a)(1)).

[[Page 14637]]

This PM emission limit does not apply during periods of startup, 
shutdown, and malfunction (SSM) (see 40 CFR 60.8(c)); only applies to 
filterable PM emissions (see 40 CFR 60.46(b)(2) and EPA Method 5 in 40 
CFR part 60, appendix A); and only applies during scenarios of firing 
coal and tire-derived fuel at Flint Creek (see Title V permit for Flint 
Creek, Permit No. 0276-AOP-R5, at 18 (Exhibit 3)). When the unit is 
firing coal with leachate injection a PM10 emission limit of 
778.4 lb/hr applies, which at maximum heat input capacity equates to 
0.12 lb/MMBtu. Since the Title V permit directs Flint Creek to ask EPA 
for a determination regarding the applicability of NSPS Subpart D 
limits for oil-firing and coal-and-oil-firing scenarios, it is not 
clear whether any PM emission limit applies to Flint Creek during oil-
firing and oil-and-coal-firing. EPA recently proposed to disapprove SSM 
exemptions from BART limits in the Kansas RH SIP (see 76 FR 52604, 
52617-18 and section 302(k) of the CAA). Because BART must reflect the 
best system of continuous emission reduction, the BART limits must 
apply at all times. The existing PM limit in the Flint Creek Title V 
permit cannot satisfy BART because the existing PM limit in the Flint 
Creek Title V permit does not apply during SSM, and there does not 
appear to be a PM limit in the Flint Creek Title V permit during oil-
firing and oil- and coal-firing. A proper BART evaluation would have 
shown that these limits do not reflect BART for Flint Creek's PM 
emissions.
    Response: In our review of the Arkansas RH SIP, we evaluated the 
determination by ADEQ that no additional PM controls are required at 
the AEP Flint Creek Boiler No. 1. ADEQ's determination was based on the 
pre-control modeling performed by ADEQ and on AEP SWEPCO's statement 
that the PM visibility modeling did not ``trip the BART impact 
threshold.'' We reviewed the pre-control modeling ADEQ performed using 
the 24-hr actual maximum emissions from the baseline period. The 
modeling results in Appendix 9.2B of the Arkansas RH SIP and presented 
in Table 7-6 of Appendix A of the TSD\145\ indicate that PM contributes 
less than 0.5% of the total visibility impacts from Flint Creek Boiler 
No. 1 at all nearby Class I areas with the exception of Upper Buffalo. 
PM contributions to visibility impacts at Upper Buffalo from Flint 
Creek are less than 2% of the total visibility impairment at this Class 
I area. On the most impacted day at Upper Buffalo, modeling the 24-hr 
actual maximum emissions demonstrates that PM contributes only 0.07 dv 
of the total 3.781 dv modeled visibility impact from the source. 
Clearly, the most effective controls to address visibility impairment 
from the source are those that would reduce emissions of visibility 
impairing pollutants other than direct emissions of PM. In this action, 
we are finalizing our proposal to disapprove Arkansas's NOX 
and SO2 BART determinations for Flint Creek Boiler No. 1, as 
ADEQ did not properly identify and evaluate NOX and 
SO2 controls to address visibility impairment from the 
source.
---------------------------------------------------------------------------

    \145\ These documents can be found in the docket associated with 
our final rulemaking.
---------------------------------------------------------------------------

    As stated in our proposed rulemaking on the Arkansas RH SIP, we 
found that the source's visibility impact from PM emissions alone is so 
minimal such that the installation of any additional PM controls on the 
source could only result in very small visibility benefit that would 
not justify any upgrades to the existing controls. This is in keeping 
with the BART Rule, which states the following:

    ``Consistent with the CAA and the implementing regulations, 
States can adopt a more streamlined approach to making BART 
determinations where appropriate. Although BART determinations are 
based on the totality of circumstances in a given situation, such as 
the distance of the source from a Class I area, the type and amount 
of pollutant at issue, and the availability and cost of controls, it 
is clear that in some situations, one or more factors will clearly 
suggest an outcome. Thus, for example, a State need not undertake an 
exhaustive analysis of a source's impact on visibility resulting 
from relatively minor emissions of a pollutant where it is clear 
that controls would be costly and any improvements in visibility 
resulting from reductions in emissions of that pollutant would be 
negligible. In a scenario, for example, where a source emits 
thousands of tons of SO2 but less than one hundred tons 
of NOX, the State could easily conclude that requiring 
expensive controls to reduce NOX would not be 
appropriate. In another situation, however, inexpensive 
NOX controls might be available and a State might 
reasonably conclude that NOX controls were justified as a 
means to improve visibility despite the fact that the source emits 
less than one hundred tons of the pollutant.'' \146\
---------------------------------------------------------------------------

    \146\ 70 FR 39116.

    Therefore, we agreed with the State that PM BART for Flint Creek 
Boiler No. 1 is the existing PM emission limit (i.e. no additional 
controls). The BART Rule provides that states may determine that for a 
given source no additional control satisfies the BART requirement for a 
particular pollutant.\147\ In our final approval of the Kansas RH SIP, 
we approved the State's determination that no additional control (and 
no new emission limit) for PM is BART for a number of sources.\148\ In 
our final approval of the Oklahoma RH SIP, we also approved the State's 
determination that no additional control (and no new emission limit) 
for PM is BART for a number of sources.\149\ In the above cases, Kansas 
and Oklahoma adopted no new PM emission limit for PM BART for 
particular sources, and EPA approved this based on the low visibility 
impact attributable to PM emissions. As such, it was not necessary for 
Arkansas to establish a new PM emission limit for BART for Flint Creek 
Boiler No. 1, as ``no additional controls'' satisfies PM BART in this 
particular case. Since no additional controls satisfies BART for Flint 
Creek Boiler No. 1, it is not problematic that the existing PM emission 
limit that Arkansas adopted in Chapter 15 of APCEC Regulation No. 19 as 
meeting PM BART for Flint Creek Boiler No. 1 (i.e. the EPA NSPS, and 
also included in the Title V permit) does not apply on a continuous 
basis and only applies to filterable PM emissions. We also clarify that 
the distinction between our approval of an existing PM emission limit 
adopted in Arkansas's Chapter 15 of APCEC Regulation No. 19 for Flint 
Creek Boiler No. 1 that does not apply during SSM and our disapproval 
of an exemption of SSM for BART in the Kansas RH SIP is that the BART 
determinations that would have exempted SSM in the Kansas RH SIP were 
not based upon the minimal visibility impact from a particular 
pollutant. Therefore, we are finalizing our proposed approval of 
Arkansas determination that PM BART is the existing PM emission limit 
in Chapter 15 of APCEC Regulation No. 19 for Flint Creek Boiler No. 1.
---------------------------------------------------------------------------

    \147\ 70 FR 39116.
    \148\ 76 FR 52604 and 76 FR 80754.
    \149\ 76 FR 16168 and 76 FR 81728.
---------------------------------------------------------------------------

    That being said, we note that the 0.1 lb/MMBtu existing PM emission 
limit (for Flint Creek Boiler No. 1) in Chapter 15 of APCEC Regulation 
No. 19, which is based on EPA's NSPS standards (40 CFR part 60, subpart 
D, Sec.  60.42(a)(1)), applies during the following firing scenarios: 
coal firing; coal and tire derived fuel (TDF) firing; and during coal 
firing with leachate injection.\150\ We are finalizing our proposed 
approval of PM BART for the AEP Flint Creek Boiler No. 1.
---------------------------------------------------------------------------

    \150\ See section IV, specific conditions 3.a., 8.a., and 17.b 
of the ADEQ Operating Air Permit for AEP-Flint Creek Power Plant 
(Permit No. 0276-AOP-R5). This permit can be viewed at http://www.adeq.state.ar.us/ftproot/pub/WebDatabases/PermitsOnline/Air/0276-AOP-R5.pdf.
---------------------------------------------------------------------------

    Comment: The existing PM limit of 0.1 lbs/MMBtu in the Entergy 
White

[[Page 14638]]

Bluff Title V permit, which EPA proposed to approve as BART for PM, is 
based on EPA's NSPS for Fossil-Fuel Fired Steam Generators that 
commenced construction after August 17, 1971 (40 CFR part 60, subpart 
D, Sec.  60.42(a)(1)). This PM emission limit does not apply during SSM 
(see 40 CFR 60.8(c)), and only applies to filterable PM emissions (see 
40 CFR 60.46(b)(2) and EPA Method 5 in 40 CFR part 60, appendix A). 
Since the Title V permit directs White Bluff to ask EPA for a 
determination regarding the applicability of NSPS Subpart D limits 
during fuel oil-firing and biodiesel firing during startup, shutdown 
and malfunction, it is not clear whether any PM emission limit applies 
to White Bluff for these scenarios. EPA recently proposed to disapprove 
SSM exemptions from BART limits in the Kansas RH SIP (see 76 FR 52604, 
52617-18 and section 302(k) of the CAA). Because BART must reflect the 
best system of continuous emission reduction, the BART limits must 
apply at all times. The existing PM limit in the White Bluff Title V 
permit cannot satisfy BART because this limit does not apply during 
SSM, and there does not appear to be a PM limit in the White Bluff 
Title V permit during fuel oil-firing and bio-diesel firing. The 
existing PM limit in the White Bluff Title V permit cannot satisfy BART 
because it does not apply during all periods of operation of the unit.
    Response: First, we disagree that we are approving the White Bluff 
Title V permit as BART for PM. We are approving the part of the Chapter 
15 of APCEC Regulation No. 19 that applies to the Entergy White Bluff 
Units 1 and 2 as BART for PM. We agree that the part of the submitted 
rule that applies to the two White Bluff units is based on EPA's NSPS 
for Fossil-Fuel Fired Steam Generators that commenced construction 
after August 17, 1971 (40 CFR part 60, subpart D, Sec.  60.42(a)(1)). 
Secondly, in our review of the Arkansas RH SIP, we evaluated the 
determination by ADEQ that no additional PM controls are required at 
the Entergy White Bluff Units 1 and 2. We reviewed the data submitted 
by ADEQ, including pre-control modeling in Appendix 9.2B of the 
Arkansas RH SIP, to evaluate the State's determination that the 
majority of visibility-causing emissions are due to emissions of 
NOX and SO2, and that no additional PM controls 
are warranted. The modeling results in Appendix 9.2B of the Arkansas RH 
SIP and presented in Table 7-7 of Appendix A of the TSD, indicate that 
PM contributes less than 0.4% of the total visibility impacts at all 
nearby Class I areas. On the most impacted day at Caney Creek, modeling 
the 24-hr actual maximum emissions, PM contributes only 0.03 dv of the 
more than 8 dv modeled visibility impact from the White Bluff Units 1 
and 2. Clearly, the majority of visibility-causing emissions are due to 
emissions of NOX and SO2 and the most effective 
controls to address visibility impairment from the units are those that 
would reduce emissions of NOX and SO2 rather than 
direct emissions of PM. In this action, we are finalizing our proposal 
to disapprove Arkansas's NOX and SO2 BART 
determinations for White Bluff Units 1 and 2, as the State did not 
properly evaluate and identify controls to address visibility 
impairment from these units.
    As articulated in our proposed rulemaking on the Arkansas RH SIP, 
we are finding that the source's visibility impact from PM emissions 
alone is so minimal such that the installation of any additional PM 
controls on the two units could only result in such small visibility 
benefits that it could not justify any upgrades to the existing 
controls. This is in keeping with the BART Rule, which states the 
following:

    ``Consistent with the CAA and the implementing regulations, 
States can adopt a more streamlined approach to making BART 
determinations where appropriate. Although BART determinations are 
based on the totality of circumstances in a given situation, such as 
the distance of the source from a Class I area, the type and amount 
of pollutant at issue, and the availability and cost of controls, it 
is clear that in some situations, one or more factors will clearly 
suggest an outcome. Thus, for example, a State need not undertake an 
exhaustive analysis of a source's impact on visibility resulting 
from relatively minor emissions of a pollutant where it is clear 
that controls would be costly and any improvements in visibility 
resulting from reductions in emissions of that pollutant would be 
negligible. In a scenario, for example, where a source emits 
thousands of tons of SO2 but less than one hundred tons 
of NOX, the State could easily conclude that requiring 
expensive controls to reduce NOX would not be 
appropriate. In another situation, however, inexpensive 
NOX controls might be available and a State might 
reasonably conclude that NOX controls were justified as a 
means to improve visibility despite the fact that the source emits 
less than one hundred tons of the pollutant.'' \151\
---------------------------------------------------------------------------

    \151\ 70 FR 39116.

    Therefore, we agree with the State that PM BART for White Bluff 
Units 1 and 2 is the existing PM emission limit in Chapter 15 of APCEC 
Regulation No. 19 (i.e. no additional controls). The BART Rule provides 
that states may determine that for a given source no additional control 
satisfies the BART requirement for a particular pollutant.\152\ In such 
cases, it is not necessary for a state to establish a new emission 
limit when no additional control is BART. In our final approval of the 
Kansas RH SIP, we approved the State's determination that no additional 
control (and no new emission limit) for PM is BART for a number of 
sources.\153\ In our final approval of the Oklahoma RH SIP, we also 
approved the State's determination that no additional control (and no 
new emission limit) for PM is BART for a number of sources.\154\ In the 
above cases, Kansas and Oklahoma adopted no new PM emission limit for 
PM BART for particular sources, and EPA approved this based on the low 
visibility impact attributable to PM emissions. As such, it was not 
necessary for Arkansas to establish a new PM emission limit for BART 
for White Bluff Units 1 and 2, as ``no additional controls'' satisfies 
PM BART in this particular case. As explained above, the distinction 
between our approval in the Arkansas RH SIP of an existing PM emission 
limit in Chapter 15 of APCEC Regulation No. 19 for White Bluff that 
does not apply during SSM and our disapproval of an exemption of SSM 
for BART in the Kansas RH SIP is that the BART determinations that 
would have exempted SSM in the Kansas RH SIP were not based upon the 
minimal visibility impact from a particular pollutant. Since no 
additional controls satisfies BART for White Bluff Units 1 and 2, it is 
not problematic that the existing PM emission limit that Arkansas 
adopted for PM BART for Units 1 and 2 does not apply on a continuous 
basis and only applies to filterable PM emissions. Therefore, we are 
finalizing our proposed approval of Arkansas determination that PM BART 
is the existing PM emission limit in Chapter 15 of APCEC Regulation No. 
19 for White Bluff Units 1 and 2.
---------------------------------------------------------------------------

    \152\ 70 FR 39116.
    \153\ 76 FR 52604 and 76 FR 80754.
    \154\ 76 FR 16168 and 76 FR 81728.
---------------------------------------------------------------------------

    Comment: The technology available for control of the pollutant in 
question is the first factor that must be evaluated in a BART analysis. 
The most effective PM control technology is a fabric filter baghouse. 
ESPs can achieve control efficiencies of 99% or better, and baghouses 
can achieve PM control efficiencies as high as 99.9% or even higher. 
Baghouses have been installed since the 1970's and are the PM control 
technology of choice for new coal-fired EGUs. Several recent PSD 
permits have been issued with best available control technology (BACT) 
limits at 0.010 lb/

[[Page 14639]]

MMBtu, based on installation of a fabric filter baghouse. Matt Haber, 
EPA Region 9's BACT expert and current Deputy Director of the Air 
Division, concluded in 2002 that BACT for filterable PM at two existing 
PC boilers firing Powder River Basin coal and equipped with a baghouse 
was 0.006 lb/MMBtu based on a 3-hour average and monitored via EPA 
Method 5 and continuously using triboelectric broken bag detectors. 
Even though AEP Flint Creek and Entergy White Bluff are subject to 
BART, and not BACT, after evaluating the achievable emission rates with 
a new baghouse at these units, there is no reason why Flint Creek and 
White Bluff could not achieve PM emission rates similar to those of a 
new unit with a baghouse. Particularly since White Bluff will be 
installing new baghouses at the two units. Even these BACT limits fail 
to reflect the low levels of filterable PM emissions that can be 
achieved with fabric filter baghouses. As early as May 2004, at least 
147 performance tests measured filterable PM/PM10 at less 
than 0.010 lb/MMBtu and 82 recorded PM/PM10 emissions less 
than 0.005 lb/MMBtu using fabric filter baghouses. The lowest reported 
PM/PM10 emission rate was 0.0004 lb/MMBtu. Other states have 
made PM BART determinations that are much lower than ADEQ's proposed 
limit of 0.1 lb/MMBtu, based on use of a baghouse. South Dakota adopted 
and EPA recently approved a PM BART emission limit of 0.012 lb/MMBtu 
for the Big Stone Power Plant, a 600 MW power plant burning Powder 
River Basin coal, and with an existing baghouse. Even though Big Stone 
is located 431 km from the nearest Class I area, EPA did not exempt the 
plant from PM BART as EPA has proposed for Flint Creek.
    Response: EPA agrees that baghouses have very high PM control 
efficiency capabilities. However, as articulated in our proposed 
rulemaking and further explained in our response to comments, due to 
the low visibility impact from the AEP Flint Creek Boiler No. 1 and the 
Entergy White Bluff Units 1 and 2 attributable to PM, we agree with 
Arkansas that the existing PM emission limit adopted for these sources 
in Chapter 15 of APCEC Regulation No. 19 satisfies BART for these 
units. As explained elsewhere in our response to comments, this is 
consistent with the BART Rule and EPA's action on other states' RH 
SIPs. We are finalizing our proposed approval of the existing PM 
emission limit as PM BART for the AEP Flint Creek Boiler No. 1 and 
Entergy White Bluff Units 1 and 2.
    With regard to the comment that White Bluff will be installing 
baghouses on Units 1 and 2, EPA is aware that Entergy White Bluff has 
canceled the proceeding before the Arkansas Public Service Commission 
to obtain a declaratory order approving the installation of these 
controls. Furthermore, as explained elsewhere in our response to other 
comments, the Arkansas RH SIP that is before EPA to act on does not 
include installation of a dry scrubber and baghouse for control of 
SO2 and PM emissions at White Bluff Units 1 and 2. 
Therefore, EPA disagrees that it should disapprove the PM BART 
determination for White Bluff Units 1 and 2 because the source may be 
considering installing these controls.
    Comment: Coal-fired boilers with hot-side ESPs, including the 
Navajo Power Plant Units, are meeting PM emission rates much lower than 
0.1 lb/MMBtu. Even if EPA finds that it is acceptable to not evaluate 
additional control technologies for PM10 at AEP Flint Creek, 
the PM10 BART limit for Flint Creek must reflect the 
technology determined to represent BART. The 0.1 lb/MMBtu PM emission 
limit of Subpart D of the NSPS does not. Because the existing PM 
emission limit of 0.1 lb/MMBtu is much higher than the maximum 24-hour 
average PM10 levels emitted by Flint Creek, the existing 
limit fails to reflect the best system of continuous emission reduction 
as required by the definition of BART in 40 CFR 51.302. There will be 
less incentive to properly operate and maintain the PM control 
equipment if the PM BART limit is unreasonably high.
    Response: As articulated in our proposed rulemaking and further 
explained in earlier response to comments, due to the low visibility 
impact from the AEP Flint Creek Boiler No. 1 attributable to PM, we 
agree with Arkansas that the existing PM emission limit in Chapter 15 
of APCEC Regulation No. 19 satisfies BART for this unit. EPA agrees 
with Arkansas that requiring the source to install and operate 
additional PM controls on this unit (including any upgrades to the 
existing PM controls) would not be justified because of the low 
visibility benefit that would result. As explained elsewhere in our 
response to comments, this is consistent with the BART Rule and EPA's 
action on other states' RH SIPs. We are finalizing our proposed 
approval of the existing PM emission limit in as PM BART for the AEP 
Flint Creek Boiler No. 1.
    Comment: Even if it was determined that the existing ESPs represent 
BART for the White Bluff Units 1 and 2, the existing PM emissions 
limits fail to reflect BART. According to ADEQ, the maximum 24-hour 
actual PM10 emission rates at White Bluff Units 1 and 2 are 
much lower than the emissions allowed by the existing PM limit in the 
White Bluff Title V permit. At an emission rate of 0.1 lbs/MMBtu, while 
firing coal and a maximum allowable heat input capacity of 8,700 lbs/
MMBtu, the maximum pound per hour emission rate would be 879 lb/hr. 
However, ADEQ modeled Entergy White Bluff's highest-24 hour actual 
PM10 emission rate as 15.592 grams per second for Unit 1 and 
16.653 grams per second for Unit 2, which equate to 123.7 lb/hr and 
132.2 lb/hr, respectively. Assuming the highest actual PM10 
emission rate occurred during the time of maximum heat input capacity, 
the maximum 24-hour actual PM10 emission rate modeled 
equates to 0.027 lb/MMBtu. In 2010, PM stack testing at White Bluff 
Units 1 and 2 showed the units were emitting filterable PM and total PM 
at rates much lower than ADEQ's PM BART limit of 0.1 lb/MMBtu, which 
under Subpart D of the NSPS only applies to filterable PM (see Exhibits 
14 and 15). With the installation of a scrubber and NOX 
controls to meet BART, the condensable PM emissions will be even lower 
than the 2010 stack testing results show. Even if EPA finds it 
acceptable to not evaluate additional control technologies for PM at 
White Bluff Units 1 and 2, the PM BART limit for the units must reflect 
the technology determined to represent BART, which in this case it does 
not. Because the existing PM emission limit of 0.1 lb/MMBtu is much 
higher than the maximum 24-hour average PM10 levels emitted 
by White Bluff, the existing limit fails to reflect the best system of 
continuous emission reduction as required by the definition of BART in 
40 CFR 51.302. There will be less incentive to properly operate and 
maintain the PM control equipment if the PM BART limit is unreasonably 
high.
    Response: As articulated in our proposed rulemaking and further 
explained in our previous response to comments, due to the low 
visibility impact from the Entergy White Bluff Units 1 and 2 
attributable to PM, we agree with Arkansas that the existing PM 
emission limit adopted in Chapter 15 of APCEC Regulation No. 19 
satisfies BART for these units. EPA agrees with Arkansas that requiring 
the source to install and operate additional PM controls on these units 
(including any upgrades to the existing PM controls) is not justified 
based on the small visibility benefit. As explained elsewhere in our 
response to comments, this is consistent with the BART Rule and EPA's 
action on other states' RH

[[Page 14640]]

SIPs. We are finalizing our proposed approval of the existing PM 
emission limit as PM BART for White Bluff Units 1 and 2.
    Comment: Other states have made PM BART determinations that are 
much lower than ADEQ's proposed limit of 0.1 lb/MMBtu for White Bluff 
Units 1 and 2. South Dakota adopted and EPA recently approved a PM BART 
emission limit of 0.012 lb/MMBtu for the Big Stone Power Plant, a 600 
MW power plant burning Powder River Basin coal, and with an existing 
baghouse. Even though Big Stone is located 431 km from the nearest 
Class I area, neither South Dakota nor EPA exempt the plant from PM 
BART as EPA has proposed for White Bluff. In Big Stone's case, South 
Dakota and EPA are following the Federal regulations regarding BART, 
which requires that sources that are subject to BART obtain BART limits 
for ``each pollutant emitted by'' the BART-eligible source (see 40 CFR 
51.301 and Appendix Y, section IV.A). The State of Wyoming has also 
adopted PM BART determinations for several EGUs that are lower than 0.1 
lb/MMBtu, including 0.042 lb/MMBtu for Naughton Unit 1; 0.054 lb/MMBtu 
for Naughton Unit 2; 0.015 lb/MMBtu for Naughton Unit 3, Dave Johnson 
Units 3 and 4, and Wyodak; and 0.03 lb/MMBtu for Jim Bridger Units 1-4.
    Response: The EPA agrees that other states have adopted PM emission 
limits more stringent than those adopted by Arkansas for PM BART. 
However, as articulated in our proposed rulemaking and further 
explained in our response to comments, due to the low visibility impact 
from White Bluff Units 1 and 2 attributable to PM, we agree with 
Arkansas that the existing PM emission limit in Chapter 15 of APCEC 
Regulation No.19 satisfies BART for these units. EPA agrees with 
Arkansas that requiring the source to install and operate additional PM 
controls on these units (including any upgrades to the existing PM 
controls) is not justified based on the small visibility benefit. Such 
was not the case with regard to the visibility impact due to direct PM 
emissions from the sources in other states referenced in the comment. 
As explained elsewhere in our response to comments, this is consistent 
with the BART Rule and EPA's action on other states' RH SIPs. We are 
finalizing our proposed approval of the existing PM emission limit as 
PM BART for Entergy White Bluff Units 1 and 2.
    Comment: The EPA proposed to approve Entergy's determination that 
PM BART for the natural gas firing scenario is the existing PM limit 
for Lake Catherine Unit 4, or 45.0 lb/hr (76 FR 64204). EPA identifies 
the PM emission limit as 45.0 lb/hr, but the permit identifies the 
PM10 limit as 44.5 lb/hr (see Exhibit 21). EPA cannot 
approve the existing PM limit as meeting BART for Lake Catherine Unit 4 
for the natural gas firing scenario because Lake Catherine's Title V 
permit does not include provisions to ensure the enforceability of the 
PM limit. There are no requirements in the permit for testing to 
determine compliance with this limit. The permit states that Condition 
9, which is a requirement to install and maintain O2 
monitors and to maintain a positive O2 reading when the 
boilers are operating, is to be used for compliance with the 
PM10 and PM limits of the permit for Lake Catherine Unit 4 
(see Exhibit 21). It is not clear how this will ensure compliance with 
the numerical PM10 emission limit of 44.5 lb/hr. The 
provisions of Condition 9 appear to be operational standards, and if 
ADEQ was relying on the O2 monitoring provision to meet BART 
for PM, the State would need to show that the operational standard will 
ensure equivalent results to the lb/hr emission limit assumed for BART 
(see 40 CFR 51.308(e)(1)(iii)). EPA cannot justify its approval of the 
unenforceable PM/PM10 limit for Lake Catherine Unit 4 based 
on its statement that PM emissions are expected to be very low from 
natural gas firing. Once a unit is determined to be subject to BART, it 
must make a determination of BART for each pollutant emitted by the 
unit.
    Response: In our review of the Arkansas RH SIP, we evaluated the 
determination by ADEQ that PM emissions from Entergy's Lake Catherine 
Unit 4 are inherently very low when burning natural gas and that as a 
result, no additional PM controls are required for the natural gas 
firing scenario. We agree with the State's conclusion, based on its 
modeling results, that the visibility impact of this unit from direct 
PM emissions alone is minimal. We note that the modeling results 
submitted by Arkansas in Appendix 9.2B of the Arkansas RH SIP indicate 
that under natural gas firing conditions, NOX contributes 
over 99.9% of Lake Catherine Unit 4's total visibility impacts at all 
nearby Class I areas on the most impacted days. Based on the State's 
modeling results, the visibility impact of this unit from direct PM 
emissions alone is so minimal such that the requirement of any 
additional PM controls on this unit would only achieve minimal 
visibility benefit and would not be justified. It is clear that the 
most effective controls to address visibility impairment from the 
source during natural gas firing are those that would reduce emissions 
of NOX. Given these conclusions, we proposed to find that 
the State reasonably concluded that BART for PM for the natural gas 
firing scenario is the existing PM emission limit for Unit 4 in Chapter 
15 of APCEC Regulation No. 19. This is consistent with the BART Rule, 
which states the following:

    ``Consistent with the CAA and the implementing regulations, 
States can adopt a more streamlined approach to making BART 
determinations where appropriate. Although BART determinations are 
based on the totality of circumstances in a given situation, such as 
the distance of the source from a Class I area, the type and amount 
of pollutant at issue, and the availability and cost of controls, it 
is clear that in some situations, one or more factors will clearly 
suggest an outcome. Thus, for example, a State need not undertake an 
exhaustive analysis of a source's impact on visibility resulting 
from relatively minor emissions of a pollutant where it is clear 
that controls would be costly and any improvements in visibility 
resulting from reductions in emissions of that pollutant would be 
negligible. In a scenario, for example, where a source emits 
thousands of tons of SO2 but less than one hundred tons 
of NOX, the State could easily conclude that requiring 
expensive controls to reduce NOX would not be 
appropriate.'' \155\
---------------------------------------------------------------------------

    \155\ 70 FR 39116.

    Based on our analysis of the data submitted by ADEQ in the Arkansas 
RH SIP, and our agreement that PM emissions from burning natural gas 
are inherently very low, we agree with the State that PM BART for Lake 
Catherine Unit 4 is the existing PM emission limit in Chapter 15 of 
APCEC Regulation No. 19 (i.e. no additional controls). The BART Rule 
provides that states may determine that for a given source no 
additional control satisfies the BART requirement for a particular 
pollutant.\156\ In such cases, it is not necessary for a state to 
establish a new emission limit when no additional control is BART. In 
our final approval of the Kansas RH SIP, we approved the State's 
determination that no additional control (and no new emission limit) 
for PM is BART for a number of sources.\157\ In our final approval of 
the Oklahoma RH SIP, we also approved the State's determination that no 
additional control (and no new emission limit) for PM is BART for a 
number of sources.\158\ In the above cases, Kansas and Oklahoma adopted 
no new PM emission limit for PM BART for particular sources, and EPA 
approved this based on the low visibility impact attributable to PM 
emissions. Arkansas adopted the

[[Page 14641]]

existing PM emission limit from the facility's existing permit as BART 
for Lake Catherine Unit 4, which is consistent with the finding that 
``no additional controls'' is sufficient to satisfy PM BART in this 
particular case. With regard to the commenter's concerns about the 
enforceability of the limit, because of the extremely low visibility 
impact of direct PM emissions from this source and the inherently low 
emissions of PM from natural gas combustion, the practical 
enforceability of this limit is not critical to our approval. We also 
note that NOX contributes over 99.9% of Lake Catherine Unit 
4's total visibility impacts at all nearby Class I areas on the most 
impacted days. Therefore, we are finalizing our proposed approval of 
Arkansas's determination that PM BART is the existing PM emission limit 
in Chapter 15 of APCEC Regulation No. 19 for the Entergy Lake Catherine 
Unit 4.
---------------------------------------------------------------------------

    \156\ 70 FR 39116.
    \157\ 76 FR 52604 and 76 FR 80754.
    \158\ 76 FR 16168 and 76 FR 81728.
---------------------------------------------------------------------------

    A review of the emissions based on AP-42 emissions factors 
substantiates that the PM emissions from natural gas combustion are 
inherently low. Table 1.4-2 of EPA's AP-42 Compilation of Air Pollutant 
Emission Factors \159\ indicates the total PM (i.e. condensable plus 
filterable PM) emission factor from combustion of natural gas is 7.6 
lb/10\6\ standard cubic feet, which is equivalent to an emission rate 
of 0.0074 lb/MMBtu.\160\ A unit's maximum emission rate for a given 
pollutant can be calculated by using the following standard equation:
---------------------------------------------------------------------------

    \159\ Compilation of Air Pollutant Emission Factors, Volume I: 
Stationary Point and Area Sources, AP-42, 5th Edition, January 1995.
    \160\ EPA's AP-42 emission factors are based on an average 
natural gas higher heating value of 1,020 Btu/standard cubic foot. 
As explained under Table 1.4-2 of EPA's AP-42 emission factors, to 
convert from 1b/10\6\ standard cubic feet to lb/MMBtu, divide by 
1,020. Based on this calculation, the 7.6 lb/10\6\ standard cubic 
feet emission factor from combustion of natural gas is equivalent to 
an emission rate of 0.0074 lb/MMBtu.

Pollutant mass emission rate (lb/hr) = Pollutant emission rate (lb/
---------------------------------------------------------------------------
MMBtu) x Unit heat input rate (MMBtu/hr)

    Accordingly, Appendix 9.1A of the Arkansas RH SIP indicates that 
the Lake Catherine Unit 4 has a heat input rate of 5,850 MMBtu/hr. 
Based on Unit 4's heat input rate and the 0.0074 lb/MMBtu PM emission 
rate from natural gas combustion, the unit's maximum mass emission rate 
for PM is 43.29 lb/hr. This is actually slightly lower than the 
existing PM emission limit for Entergy Lake Catherine Unit 4 as of 
October 15, 2007 (i.e. 45 lb/hr).
    With regard to the comment that the Entergy Whit Bluff Title V 
permit identifies the PM10 limit as 44.5 lb/hr, EPA is 
approving the part of Chapter 15 of APCEC Regulation No. 19 \161\ that 
establishes PM BART for the natural gas firing scenario for Entergy 
Lake Catherine Unit 4. The Title V permit that was in effect at the 
time of the State's adoption of Chapter 15, Regulation 19, which is 
Permit No. 1717-AOP-R4, required Unit 4 to meet a PM emission limit of 
45 lb/hr. The Title V permit referenced by the commenter is Permit No. 
1717-AOP-R5, and appears to contain revisions to several emission 
limits, including the PM emission limit for Unit 4. However, EPA can 
act only upon what is submitted to it by a state as a SIP revision. 
Arkansas submitted Chapter 15, Regulation 19 as part of its RH SIP 
revision. The State's submitted RH Rule adopts the existing PM emission 
limit as of October 15, 2007 (i.e. 45 lb/hr) as the PM BART emission 
limit.
---------------------------------------------------------------------------

    \161\ The Arkansas RH SIP was originally submitted to EPA on 
September 23, 2008. We received a revision to the RH SIP on August 
3, 2010, and a supplemental submittal on September 27, 2011. The 
revisions to Chapter 15 of APCEC Regulation 19 that we are referring 
to were submitted to us in the August 3, 2010 RH SIP revisions.
---------------------------------------------------------------------------

    The EPA is finalizing its approval of the existing PM emission 
limit as meeting PM BART for Entergy Lake Catherine Unit 4 for the 
natural gas firing scenario.
4. Comments on the Capacity Factor Used in the State's BART Analyses 
for Entergy Lake Catherine and White Bluff
    Comment: The EPA was incorrect in its assessment of Entergy's Lake 
Catherine BART determination that Entergy's Lake Catherine Unit 4 
assumption of a 10% capacity unit needs to be supported by an 
enforceable limit. A 10% capacity factor for Catherine Unit 4 is a 
conservative assumption as demonstrated by the following table:

                                                      Lake Catherine Unit 4 Annual Capacity Factor
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                          2011 (1/1-11/
      2003              2004             2005             2006             2007             2008             2009             2010             31)
--------------------------------------------------------------------------------------------------------------------------------------------------------
         10.4               3.2              4.2              0.5              0.7              2.7              3.0              3.1              2.5
--------------------------------------------------------------------------------------------------------------------------------------------------------

    This is consistent with the BART Guidelines because the baseline 
emissions rate represents a realistic depiction of anticipated annual 
emissions for the source and actual emissions for existing sources 
subject to BART should be based from a baseline period by the state. 
The BART Guidelines provide that only if future operating parameters 
differ from past practices and they have a deciding effect in the BART 
determination, then these parameters need to be enforceable limits. 
Consistent with the BART Guidelines, annual emissions for Entergy Lake 
Catherine Unit 4 were estimated based on the continuation of past 
practice of using 10% capacity for future emissions. Therefore, an 
enforceable permit limitation is not required for a 10% capacity use of 
Entergy Lake Catherine Unit 4.
    Response: The EPA agrees that in our proposed rulemaking on the 
Arkansas RH SIP we made an error in our calculation of the capacity 
factor for recent years for Entergy Lake Catherine Unit 4. Based on 
certain statements made in the BART analysis for Lake Catherine, to the 
effect that in the future the unit was expected to be dispatched 
approximately 10% of the time only, we were under the impression that 
the source had factored into their cost analysis that the unit would 
only be operating 10% of the time when the unit has historically 
operated at considerably more than 10% of the time. Based on the 
information provided by the commenter, we agree that the source has 
historically operated at less than a 10% capacity factor. We also agree 
that the BART Guidelines provide that for the purpose of calculating 
the cost of controls, the state may calculate baseline emissions based 
upon continuation of past practice.\162\
---------------------------------------------------------------------------

    \162\ Appendix Y to Part 51, section IV.4.
---------------------------------------------------------------------------

    However, our finding that the State did not properly document the 
cost analysis for NOX controls for the fuel and gas firing 
scenarios and SO2 and PM controls for the fuel oil firing 
scenario for Lake Catherine Unit 4 has not changed, as the proper 
documentation necessary to allow us to make an informed and proper 
evaluation of the BART analysis was not included in the SIP, as the 
BART Guidelines require. As explained in our proposed rulemaking, the 
RH SIP includes the results of a

[[Page 14642]]

computerized model the source used to calculate the costs associated 
with each NOX control technology for both the natural gas 
and fuel oil firing scenarios. However, the SIP includes no detailed 
breakdown of the costs. The only explanation of the computerized model 
is a paragraph in Appendix 9.3B, which points out that inputs that went 
into the model were based on inputs derived from the EPRI document 
entitled ``Retrofit NOX Control Guidelines for Gas and Oil 
Fired Boilers,'' \163\ which were further analyzed to reflect 
performance expected for Lake Catherine Unit 4, as according to the 
source ``each specific boiler will perform differently due to the 
unique characteristics of that boiler.'' \164\ The BART Guidelines 
provide that states should include documentation for any additional 
information used for the cost calculations, including any information 
supplied by vendors that affects your assumptions regarding purchased 
equipment costs, equipment life, and other elements of the 
calculation.\165\ This was not done in the Arkansas RH SIP.
---------------------------------------------------------------------------

    \163\ EPRI document entitled ``Retrofit NOX Control 
Guidelines for Gas and Fired Boilers,'' Version 2, June 1997.
    \164\ See Appendix 9.3B of the RH SIP.
    \165\ Appendix Y to Part 51, section IV.4.
---------------------------------------------------------------------------

    Furthermore, as noted in our proposed rulemaking on the Arkansas RH 
SIP, the State did not properly consider NOX post-combustion 
controls in the BART analysis for natural gas firing and fuel oil 
firing. As pointed out by another comment, the State eliminated post-
combustion controls from consideration because they were found to be 
not cost-effective and the State eliminated two NOX control 
options (for natural gas firing) involving a combination of combustion 
controls because of their incremental cost-effectiveness. Based on the 
information provided from the source's computerized model, the cost-
effectiveness of a combination of combustion controls and SNCR is 
$3,378/NOX ton removed for the natural gas firing scenario 
and $3,440/NOX ton removed for the fuel oil firing scenario. 
This is not an unreasonably high cost-effectiveness value, and 
depending on the visibility impact of these controls and the 
consideration of any of the other statutory factors, the State may find 
that these controls are BART. In light of Entergy Lake Catherine's pre-
control visibility impact of 6.607 dv and post-control visibility 
impact of 3.671 dv at Caney Creek for the fuel oil firing scenario, 
which is based on the BART controls adopted by the State in Chapter 15, 
Regulation 19 (i.e. for NOX BART this consists of boiler 
tuning, boiler modifications, and burners out of service), we believe 
that it is possible that NOX and SO2 controls 
more stringent than those adopted by the State, including post-
combustion controls, would be cost-effective and help reduce the 
visibility impact of the source at Arkansas and Missouri Class I areas. 
Therefore, the State should have evaluated both the cost-effectiveness 
and the incremental cost-effectiveness in addition to the visibility 
impact of post-combustion controls and each of the other control 
options considered at each potentially affected Class I area before 
eliminating any given control option. It appears that the source and 
the State may have only considered the incremental cost-effectiveness 
of controls in eliminating post-combustion controls and all other 
controls more stringent than the controls adopted by the State for 
NOX BART. The BART Guidelines provide that average cost-
effectiveness (reported by the source to be $1,701/ton NOX 
removed and $3,757/ton NOX removed for the two sets of 
combination of controls mentioned above for the natural gas firing 
scenario), in addition to the visibility impacts at each potentially 
affected Class I area, should also be taken into consideration before a 
BART determination is made.
    In addition, as articulated in our proposed rulemaking on the 
Arkansas RH SIP, the State did not consider SO2 post-
combustion controls in the BART analysis for fuel oil firing. 
Furthermore, as noted in our proposed rulemaking, the use of a wet 
scrubber system that controls both SO2 and PM emissions may 
prove to be cost-effective and provide for substantial visibility 
improvement. As explained elsewhere in our response to comments, in 
light of Entergy Lake Catherine's pre-control visibility impact of 
6.607 dv and post-control visibility impact of 3.671 dv at Caney Creek 
for the fuel oil firing scenario,\166\ we believe that it is possible 
that NOX, SO2, and PM controls more stringent 
than those adopted by the State in Chapter 15 of APCEC Regulation No. 
19, including post-combustion controls, would be cost-effective and 
help reduce the visibility impact of the source at Arkansas and 
Missouri Class I areas.
---------------------------------------------------------------------------

    \166\ See Tables 9.4f and 9.4e of the Arkansas RH SIP. The pre- 
and post-control visibility impact reported is the maximum 
[Delta]dv. The post-control visibility impact is the visibility 
impact resulting from the BART controls adopted by the State.
---------------------------------------------------------------------------

    Therefore, we are finalizing our proposed disapproval of BART for 
the Entergy Lake Catherine Unit 4 for NOX for both the 
natural gas and fuel oil firing scenarios, and SO2 and PM 
for the fuel oil firing scenario.
    Comment: The EPA was incorrect in criticizing the cost-analysis 
conducted for Entergy's White Bluff Units 1 and 2 because the source 
assumed 85% utilization of the units without an enforceable limit when 
the EPA believes that the units are capable of utilization of 100% 
capacity factor. Utilization of 85% capacity factor for these units is 
a conservative assumption, as demonstrated by the following table:

                                                              White Bluff Capacity Factors
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                           2011 (1/1-11/
                              Unit                                  2003     2004     2005     2006     2007     2008     2009     2010         31)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1...............................................................     75.3     73.4     63.1     55.1     81.3     78.2     71.1     82.5            60.7
2...............................................................     58.7     74.4     63.0     74.8     54.3     71.5     74.6     65.5            71.9
--------------------------------------------------------------------------------------------------------------------------------------------------------

    This is consistent with the BART Guidelines because the baseline 
emissions rate represents a realistic depiction of anticipated annual 
emissions for the source and actual emissions for existing sources 
subject to BART should be based from a baseline period by the state. 
The Guidelines provide that only if future operating parameters differ 
from past practices and they have a deciding effect in the BART 
determination, then these parameters need to be enforceable limits. 
Consistent with the Guidelines, annual emissions from Entergy White 
Bluff Units 1 and 2 were estimated based on the continuation of past 
practice of using 85% capacity for future emissions. Therefore, an 
enforceable permit limitation is not

[[Page 14643]]

required for an 85% capacity use of Entergy White Bluff Units 1 and 2.
    Response: The EPA agrees that in our proposed rulemaking on the 
Arkansas RH SIP we made an error in our calculation of the capacity 
factor for recent years for Entergy White Bluff Units 1 and 2. Based on 
certain statements made in the BART analysis for White Bluff, to the 
effect that in the future the unit was expected to be dispatched 
approximately 85% of the time only, we were under the impression that 
the source had factored into their cost analysis that the unit would 
only be operating 85% of the time when the unit has historically 
operated at more than this. Based on the information provided the 
commenter, we agree that the source has historically operated at 
slightly less than an 85% capacity factor. We also agree that the BART 
Guidelines provide that for the purpose of calculating the cost of 
controls, the state may calculate baseline emissions based upon 
continuation of past practice.\167\
---------------------------------------------------------------------------

    \167\ Appendix Y to Part 51, section IV.4.
---------------------------------------------------------------------------

    However, our finding that the State did not properly document the 
cost analysis for NOX and SO2 controls for both 
the bituminous and sub-bituminous coal firing scenarios for White Bluff 
Units 1 and 2 has not changed. As articulated in our proposed 
rulemaking, the proper documentation necessary to allow an informed and 
proper evaluation of the BART analysis was not included in the SIP, as 
the BART Guidelines require. As pointed out in another comment, the 
annual cost estimates of NOX combustion controls in the BART 
analysis for White Bluff Units 1 and 2 are significantly higher than 
those of similar controls at comparable facilities. The State must 
provide documentation of its cost calculations and a reasonably 
detailed breakdown of the costs. The State must also document the 
reason for any unusually high costs, which may require a higher level 
of detail in cost breakdown. Furthermore, the State did not properly 
consider the available controls and cost of controls because it did not 
evaluate SO2 and NOX controls that can achieve 
emission limits more stringent than the presumptive emission limits. As 
articulated in more detail in our proposed rulemaking, some of the 
control technologies evaluated by the State for SO2 are 
capable of achieving a higher control efficiency than that evaluated by 
the State, and there are NOX control technologies capable of 
achieving a more stringent limit than the presumptive limit. Because 
such controls have been found to be cost-effective at similar 
facilities, the State must evaluate the costs and visibility impact of 
these controls before making a BART determination. Moreover, as 
articulated in our proposed rulemaking and in previous response to 
comments, the RHR, BART Guidelines, and CAA require that states 
consider the controls available, including the most stringent control 
technology, as well as the maximum level of control achievable by each 
technology.
    Therefore, we are finalizing our proposed disapproval of the 
NOX and SO2 BART determinations for the Entergy 
White Bluff Units 1 and 2 for both the bituminous and sub-bituminous 
coal firing scenarios.
5. Comments on the State's Cost Evaluations
    Comment: The ``cost of compliance'' is a BART consideration factor 
that should be properly left to the states and EPA cannot void a 
state's cost assessment on the grounds that EPA would have used a 
different analysis or would have reached a different conclusion if it 
had primary jurisdiction.
    Response: The EPA agrees that the BART Rule provides states with 
some flexibility in how they calculate and consider costs.\168\ 
However, our grounds for disapproving Arkansas's NOX BART 
determinations (natural gas and fuel oil firing conditions) and 
SO2 BART determination (fuel oil firing conditions) for 
Entergy Lake Catherine Unit 4 and the NOX and SO2 
BART determinations (bituminous and sub-bituminous coal firing 
conditions) for Entergy White Bluff Units 1 and 2, as articulated in 
our proposal, are not based on EPA arriving at a different BART 
determination. Our disapproval of the above BART determinations is 
based in part on the fact that the State did not provide the proper 
documentation, as required by the BART Guidelines.\169\ The BART 
Guidelines provide that states must develop estimates of capital and 
annual costs and document the basis for equipment cost estimates either 
with data supplied by a vendor (i.e. budget estimates or bids) or by a 
referenced source (such as the OAQPS Control Cost Manual).\170\ The 
BART Guidelines also provide that cost estimates should be based on the 
OAQPS Control Cost Manual, where possible, to maintain and improve 
consistency, and that states should include documentation for any 
additional information used in cost calculation. The State did not 
satisfy this requirement in the above BART determinations because the 
State provided no documentation, breakdown, or any sufficiently 
detailed supporting information for its cost analyses. Without the 
documentation, neither we nor the public have the basis to verify the 
validity of either the cost estimates or Entergy's BART determination 
based on the cost estimation. As pointed out in another comment, the 
annual cost estimates of NOX combustion controls in the 
State's BART analysis for White Bluff Units 1 and 2 are significantly 
higher than those of similar controls at comparable facilities. In 
summary, our disapproval for these BART determinations is based (among 
other reasons) on the fact that the proper documentation necessary to 
allow us to make an informed and proper evaluation of the BART analysis 
was not included in the SIP, as the BART Guidelines require.
---------------------------------------------------------------------------

    \168\ 70 FR 39127.
    \169\ Appendix Y to Part 51, section IV.4.
    \170\ Appendix Y to Part 51, section IV.4.
---------------------------------------------------------------------------

    Comment: The EPA claims that Arkansas's BART determinations should 
be disapproved because they rely on cost estimates that are not 
adequately documented or that lack sufficiently detailed supporting 
information (76 FR 64206), yet EPA fails to provide any specific 
discussion in the proposed rule's preamble of the purported 
shortcomings in the state's cost information and fails to describe the 
type or degree of documentation it believes is mandated. In other 
similar RH SIP rulemakings, EPA has described a level of cost estimate 
documentation that is of such an extensive and detailed nature that it 
cannot be reasonably deemed an appropriate requirement of a BART cost 
assessment (76 FR 52388, 52396).
    Response: The EPA disagrees that our proposed rulemaking did not 
provide any specific discussion on the type or degree of documentation 
needed in a state's cost evaluation. Our proposed rulemaking and the 
TSD for our proposed rulemaking both specify that the basis for 
equipment cost estimates should be documented either with data supplied 
by an equipment vendor or by a referenced source, such as the OAQPS 
Control Cost Manual. Our proposed rulemaking also specified that for 
the SO2 BART analysis for fuel oil firing for Entergy Lake 
Catherine Unit 4, the State should clearly indicate the quantity of 
fuel oil consumption on which the State's annual cost calculation is 
based. However, the BART Guidelines set specific requirements regarding 
this matter. The BART Guidelines provide that states should base their 
cost estimates on the OAQPS Control Cost Manual, where possible, and 
that the level of detail in the Cost Control

[[Page 14644]]

Manual addresses most control technologies in sufficient detail for a 
BART analysis. In general, a state should include a reasonably detailed 
line by line breakdown of the cost estimates, and document the vendor 
and/or referenced source. However, as explained in the BART Guidelines, 
where unusual costs due to site-specific design or other conditions are 
factored into the cost calculation, this should also be documented 
properly. For cases involving unusual costs, such as was the case at 
the San Juan Generating Station in New Mexico,\171\ which was subject 
to a FIP for BART controls (which the comment references), a higher 
level of detail in documentation may be necessary. Furthermore, the 
State is encouraged to work with EPA to determine the appropriate level 
of detail needed for any future BART analyses to be submitted to EPA as 
SIP revisions.
---------------------------------------------------------------------------

    \171\ 76 FR 52388.
---------------------------------------------------------------------------

    Comment: The EPA found that Entergy's cost evaluation for BART for 
NOX and SO2 for White Bluff Units 1 and 2 was 
deficient because the company assumed 85% utilization of the two units 
when they are not subject to any federally enforceable limit on 
utilization, and the units are capable of 100% utilization. We agree 
with EPA's concerns that by assuming 85% utilization of the White Bluff 
units under the proposed NOX and SO2 BART limits, 
Entergy underestimated the tons of NOX and SO2 
emissions that would be reduced and overestimated the costs per ton of 
pollutant removed for the combustion controls evaluated. The EPA also 
found that the cost analysis is inadequate because Entergy did not take 
into account the achievable emissions reductions with the control 
technologies evaluated. We agree with EPA's finding that Entergy did 
not adequately evaluate the cost-effectiveness of controls in the 
NOX and SO2 BART analyses for White Bluff Units 1 
and 2.
    Response: Based on comments received during the public comment 
period, it has come to our attention that we made an error in the 
calculation of the capacity factors for White Bluff Units 1 and 2. 
Based on the information provided, we agree that the source has 
historically operated at a slightly less than 85% capacity factor. The 
BART Guidelines provide that for the purpose of calculating the cost of 
controls, the state may calculate baseline emissions based upon 
continuation of past practice.\172\ However, our finding that the State 
did not properly document the cost analysis for NOX and 
SO2 controls for White Bluff Units 1 and 2 has not changed, 
as the proper documentation necessary to allow us to make an informed 
and proper evaluation of the BART analysis was not included in the SIP, 
as the BART Guidelines require. As pointed out in another comment, the 
annual cost estimates of NOX combustion controls in the BART 
analysis for White Bluff Units 1 and 2 are significantly higher than 
those of similar controls at comparable facilities. In addition, the 
State did not properly consider the available controls and cost of 
controls because it did not evaluate SO2 and NOX 
controls to achieve emissions limits more stringent than the 
presumptive emission limits. As articulated in more detail in our 
proposed rulemaking, some of the control technologies evaluated by the 
State for SO2 are capable of achieving a higher control 
efficiency than that evaluated by the State, and there are 
NOX control technologies capable of achieving a more 
stringent limit than the presumptive limit. Because such controls have 
been found to be cost-effective at similar facilities, the State must 
evaluate the costs and visibility impact of these controls in making a 
BART determination. Furthermore, as articulated in our proposed 
rulemaking and in previous response to comments, the RHR, BART 
Guidelines, and CAA require that states consider the most stringent 
control technology, as well as the maximum level of control achievable 
by each technology.
---------------------------------------------------------------------------

    \172\ Appendix Y to Part 51, section IV.4.
---------------------------------------------------------------------------

    Comment: Comparing Entergy's stated costs for SO2 
controls with those found in other companies' SO2 BART 
evaluations, it appears that Entergy has overstated the costs of 
SO2 controls. Entergy assumes much higher cost numbers for 
SO2 controls in its revised 2008 BART analysis for White 
Bluff than in its 2006 BART analysis (see Exhibit 11). The 
SO2 control cost numbers in Entergy's revised 2008 BART 
analysis for White Bluff are much higher than the cost numbers in other 
plants' SO2 BART analyses (see Exhibit 17). Even though 
Entergy's revised 2008 BART analysis for White Bluff is not before EPA 
for approval, these comments are being provided now in case the revised 
2008 BART analysis is eventually submitted to EPA. EPA should require 
that Entergy's cost-effectiveness calculations are based on the 
emission reductions achievable with the controls being evaluated and 
that Entergy's cost-analysis is well-documented, sound, and that the 
documentation and details be made publicly available.
    Response: The EPA agrees that the 2008 BART analysis for Entergy 
White Bluff is not before EPA to take action on. As far as EPA is 
aware, the State has not revised the RH SIP to include Entergy White 
Bluff's revised analysis. As such, it is unclear whether the State 
plans to submit it to EPA in the future as a SIP revision. However, we 
do agree that the cost numbers in the 2008 analysis are considerably 
higher than those in the 2006 BART analysis that is before EPA to take 
action on. Consistent with the action we are taking on the Arkansas RH 
SIP in this rulemaking, if the State submits the revised 2008 BART 
analysis to EPA in the future in the context of an official RH SIP 
revision, the State must provide documentation of its cost calculations 
and a reasonably detailed breakdown of the costs. The State will also 
have to document the reason for any unusually high costs, which may 
require a higher level of detail in cost breakdown. If the State 
anticipates submitting a revised BART analysis for White Bluff or any 
other source to EPA as a SIP revision, EPA encourages the State to work 
with us to resolve any uncertainties it may have with regard to the 
level of detail needed in the cost analysis. Consistent with the action 
we are taking on the Arkansas RH SIP in this rulemaking, we agree that 
the State must ensure that its BART analyses evaluate the most 
stringent emission limit achievable by each control considered, and 
that the cost-analysis be well-documented, sound, and that the 
documentation and all other relevant details are made publicly 
available.
    Comment: It appears that the annual cost estimates of 
NOX combustion controls in Entergy's December 2006 BART 
analysis for the Entergy White Bluff Units 1 and 2 are very high ($5.2 
million for Unit 1 and $5.3 million for Unit 2) compared to the cost 
estimates for similar controls at other coal-fired EGUs, such as those 
at the Boardman Power Plant (617 MW, $3.7 million), the Four Corners 
Power Plant (790 MW, $3.0 million), and the Sherburne County Power 
Plant (690 MW, $2.2 million) (see Exhibit 19). Since neither Entergy 
nor ADEQ have provided the specific details that went into these cost 
estimates, it is difficult to discern why Entergy's cost estimates are 
much higher.
    Response: The EPA agrees with the comment that the cost estimates 
Arkansas provided in the cost evaluation of NOX combustion 
controls in the 2006 Entergy White Bluff BART analysis are considerably 
higher than the cost estimates for similar controls at the other coal 
fired EGUs. The EPA notes that the Entergy White Bluff Units 1 and 2 
have a slightly greater generating capacity (850 MW each), but because 
of the lack of detail in Entergy White Bluff's cost calculations, it is 
not

[[Page 14645]]

clear what issues are attributing to the wide difference in the 
annualized cost estimates. As explained in our proposed rulemaking, the 
State must provide proper documentation of all cost calculations, and a 
reasonably detailed breakdown in costs. In cases where the State finds 
that cost of controls are unusually high, especially in comparison to 
the cost of the same controls at other similar sources, the State must 
provide a more detailed breakdown of costs, as provided in the BART 
Guidelines.\173\
---------------------------------------------------------------------------

    \173\ Appendix Y to Part 51, section IV.4.
---------------------------------------------------------------------------

    Comment: The EPA was incorrect in its assessment of Entergy's Lake 
Catherine Unit 4 BART determination that Entergy provided no 
documentation or detailed breakdown of cost. Entergy only included the 
expected capital cost and any impacts the control technology will have 
on the unit heat rate in the cost estimate, which is a conservative 
cost estimate of the cost of each control technology. Entergy's methods 
of calculations are described in the Appendix of the Determination 
Report. This approach is supported by EPA's BART Guidelines. In 
addition, by incorporating the costs provided by Entergy in the RH SIP 
Arkansas supports Entergy's cost analysis.
    Response: The comment appears to be in contradiction with what was 
documented in Arkansas's RH SIP. In Appendix 9.3B of the Arkansas RH 
SIP, Entergy states that a computerized model was used to evaluate 
electrical generating unit performance and the capital and operation 
and maintenance cost associated with each identified control 
technology. As such, the State should provide proper documentation of 
the equipment costs with data supplied by an equipment vendor or by a 
referenced source, and include a reasonably detailed breakdown of all 
cost estimates. The Appendix to the Determination Report referenced in 
the comment appears to be ``Appendix A: Cost and Emissions Estimates 
for NOX and SO2 Control Options.'' \174\ This 
document contains the total annual cost (with no breakdown), the cost-
effectiveness and the incremental cost-effectiveness calculated by 
Entergy of the controls considered in the BART analysis, along with 
formulas that were used by the source in calculating costs (i.e. total 
capital requirement, levelized control cost, etc.). But the actual 
calculations or numbers that went into these formulas are not included. 
As explained in our response to other comments, this approach is not 
supported by the BART Guidelines. We also note that the State's support 
for a particular cost analysis alone is not grounds for EPA approval. 
The EPA must evaluate the details of a cost analysis and determine 
whether it meets the RH requirements and BART Guidelines before we can 
consider it in approving or disapproving a BART determination.
---------------------------------------------------------------------------

    \174\ See ``BART Analysis for Lake Catherine Plant- Unit 4,'' 
prepared by Robert Paine, dated December 2006 (Appendix 9.3A of the 
Arkansas RH SIP).
---------------------------------------------------------------------------

    Comment: Entergy demonstrated that post-combustion NOX 
controls for Lake Catherine Unit 4 are not economically viable. Thus, 
EPA should not have disapproved Lake Catherine Unit 4's BART 
determination on the grounds that post-combustion controls were not 
evaluated. ADEQ noted that in the BART analysis for Lake Catherine 
facility Entergy used a computerized model that evaluated EGU 
performance and the cost associated with each identified technology. 
Entergy's analysis started with the most economical control technology 
and then conducted a stepped approach where the next economical control 
was analyzed. The analysis continued with a combination of all 
identified control technologies. Entergy reported the combination of 
control technologies until that combination was no longer cost 
effective. This is consistent with the BART Guidelines which provide 
that in the BART review, one or more of the available control options 
may be eliminated from consideration if it is demonstrated to be 
technically infeasible or to have unacceptable energy, cost, or non-air 
quality environmental impacts on a case by case basis. The incremental 
NOX control cost of $41,739/ton (option 5) and $10,101/ton 
(option 4) shown in the Lake Catherine BART analysis do not pass the 
cost test as described in the BART Guidelines. This is consistent with 
the BART Guidelines, which provide that installation of current 
combustion control technology is cost-effective and should be 
considered in determining BART for oil- and gas-fired sources.
    Response: As noted in our proposed rulemaking, we agree that the RH 
SIP includes the results of a computerized model the source used to 
calculate the costs associated with each technology. However, the SIP 
includes no detailed breakdown of the costs. The only explanation of 
the model is a paragraph in Appendix 9.3B, which points out that inputs 
that went into the model were based on inputs derived from the EPRI 
document entitled ``Retrofit NOX Control Guidelines for Gas 
and Oil Fired Boilers,'' \175\ which were further analyzed to reflect 
performance expected for Lake Catherine Unit 4, as ``each specific 
boiler will perform differently due to the unique characteristics of 
that boiler.'' \176\ The BART Guidelines provide that States should 
include documentation for any additional information used for the cost 
calculations, including any information supplied by vendors that 
affects the assumptions regarding purchased equipment costs, equipment 
life, and other elements of the calculation.\177\ We find that this 
documentation was not provided by Arkansas.
---------------------------------------------------------------------------

    \175\ EPRI document entitled ``Retrofit NOX Control 
Guidelines for Gas and Fired Boilers,'' Version 2, June 1997.
    \176\ See Appendix 9.3B of the RH SIP.
    \177\ Appendix Y to Part 51, section IV.4.
---------------------------------------------------------------------------

    The comment states that post-combustion controls were eliminated 
from consideration because they were found to be not cost-effective. 
Based on the information provided from the Entergy's computer model, 
the cost-effectiveness of a combination of combustion controls and SNCR 
is $3,378/NOX ton removed. Again, the issue of documentation 
aside, we find that Arkansas should have evaluated the visibility 
impact of this and each of the other control options considered at each 
potentially affected Class I area before eliminating any given control 
option. The comment also notes that some control options, including 
options 4 and 5 that are each a combination of combustion controls, 
were eliminated from consideration based on their incremental cost-
effectiveness. However, the BART Guidelines provide that the average 
cost-effectiveness (which was reported by the source to be $1,701/ton 
for option 4 and $3,757/ton for option 5), in addition to the 
visibility impacts from the installation of controls at each 
potentially affected Class I area, should also be taken into 
consideration before a BART determination is made. Based on average 
cost effectiveness, these options should not be eliminated from 
consideration. As the BART Guidelines explain, cost effectiveness 
cannot be assessed without an analysis of the projected visibility 
benefit. This holds true even for control options evaluated on the 
basis of their incremental cost effectiveness. In the preamble to the 
BART Rule, in response to comments that modeling should not be included 
as part of a BART review, EPA supported its decision to include 
modeling by stating that CAA section 169(g)(2) clearly requires an 
evaluation of the expected degree of improvement

[[Page 14646]]

in visibility from BART Controls.\178\ The BART Rule also states the 
following:
---------------------------------------------------------------------------

    \178\ 70 FR 39129.

    ``We believe that modeling, which provides model concentration 
estimates that are readily converted to deciviews, is the most 
efficient way to determine expected visibility improvement.'' \179\
---------------------------------------------------------------------------

    \179\ 70 FR 39129.

    Furthermore, in the preamble to the BART Rule, in response to 
---------------------------------------------------------------------------
comments received, we stated the following:

    ``We agree with commenters who asserted that the method for 
assessing BART controls for existing sources should consider all of 
the statutory factors.'' \180\
---------------------------------------------------------------------------

    \180\ 70 FR 39130.

    Therefore, Arkansas must evaluate all five statutory factors before 
eliminating a given control option, especially if there are no unusual 
circumstances that would make it clear that a particular control option 
should be eliminated before all five statutory factors are considered. 
With regard to the comment that the BART Guidelines provide that 
installation of current combustion control technology is cost-effective 
and should be considered in determining BART for oil- and gas-fired 
sources, we note the context of that statement is with regard to 
whether we believed a presumptive emission limit was appropriate for 
oil and gas fired EGUs.\181\ It was not intended to limit the 
consideration for BART of possible post-combustion control options.
---------------------------------------------------------------------------

    \181\ Appendix Y to Part 51, section IV.E.5.
---------------------------------------------------------------------------

    Comment: Arkansas's failure to consider the actual costs of 
compliance for its BART determination is reflected by the APCEC 
rulemaking record for the Arkansas RH SIP. No actual costs of 
compliance with presumptive limits for the White Bluff and Flint Creek 
facilities are provided. The petition to initiate rulemaking before the 
APCEC contains no information about the costs to install the required 
control technology at these two plants nor does it identify or contain 
any explanation of the five BART factors that the APCEC is supposed to 
consider under the CAA. The financial documentation filed in support of 
the petition contains no indication of the actual costs of compliance. 
The documentation suggests that the financial impact of the rule to the 
citizens and ratepayers of Arkansas would be zero. Thus, Arkansas 
should not have adopted EPA's presumptive limits for the Entergy White 
Bluff Units 1 and 2 and AEP Flint Creek Boiler 1 without first 
determining whether the assumptions underlying those presumptive 
emission limits, including the costs of compliance, were still valid 
and reasonable.
    Response: EPA notes that the APCEC is the State's rulemaking body 
for environmental regulations. EPA agrees that the rulemaking record 
for the Arkansas RH SIP lacks sufficient information to support the 
State's BART determinations for the two facilities. As reflected in our 
proposed rulemaking and in our previous response to comments, the State 
should have conducted a proper evaluation of the five statutory factors 
before adopting the NOX and SO2 presumptive 
limits for BART for Entergy White Bluff Units 1 and 2 and Flint Creek 
Boiler 1.
6. Comments on the August 2008 Revised BART Analysis for White Bluff
    Comment: The EPA's evaluation of the BART submittal for Entergy 
White Bluff Units 1 and 2 is based on a December 2006 BART analysis 
submitted by Entergy Arkansas Inc., and included in the Arkansas RH SIP 
in Appendix 9.3A. Entergy subsequently submitted a revised BART 
analysis to ADEQ for White Bluff on August 8, 2008 (see Exhibit 11), 
stating that this revised document should supersede the Entergy's 
original December 2006 BART determination for White Bluff. It does not 
appear that ADEQ ever adopted the revised BART analysis as part of the 
Arkansas RH SIP, but in 2009 ADEQ did propose to issue a Title V permit 
for White Bluff that proposed to incorporate the control equipment 
proposed by Entergy in its revised 2008 BART analysis to meet BART. 
These controls differed from the controls assumed to meet BART in 
Entergy's 2006 BART analysis. Specifically, the 2006 BART analysis 
proposed to install wet scrubbers to achieve the SO2 
presumptive limit of 0.15 lb/MMBtu and no additional controls for PM, 
while the revised 2008 BART analysis proposed to install dry scrubbers 
and baghouses to meet the SO2 presumptive limit of 0.15 lb/
MMBtu and no additional controls for PM. Although ADEQ never issued the 
permit it proposed in 2009, it appears that Entergy may intend to 
change its planned controls to meet BART. The EPA's proposal does not 
mention Entergy's revised 2008 BART analysis because it has not yet 
been adopted by Arkansas as a SIP revision, and it is therefore not 
before EPA to approve or disapprove. However, as EPA acts on the 
Arkansas RH SIP, it must consider that Entergy may be installing a 
baghouse as part of its SO2 controls. Since a baghouse is 
more effective at controlling PM emissions than an ESP, EPA should not 
act on the state's proposed PM BART limit until it has a complete and 
approvable suite of BART controls that it is acting on or otherwise 
promulgating as a FIP.
    Response: The EPA agrees that the December 2006 White Bluff BART 
analysis is what was included in Appendix 9.3A of the Arkansas RH SIP 
received by EPA on September 23, 2008. As such, that is the BART 
analysis that is before EPA to take action on. EPA does not have the 
authority to take action on a SIP revision that has never been 
officially submitted by the State. As the comment notes, the controls 
assumed to meet BART in Entergy's 2008 revised BART analysis differ 
from those in the 2006 BART analysis that was submitted to EPA as part 
of the Arkansas RH SIP. However, since to the best of EPA's knowledge, 
the State has never officially adopted the 2008 revised BART analysis 
as a revision to the Arkansas RH SIP and since the State never issued 
the permit that proposed to install the controls in the 2008 revised 
BART analysis, it is not clear if the State is even considering 
submitting such a revised SIP to EPA. As such, EPA can only review what 
has been submitted to it by Arkansas. Therefore, we are basing our 
decision upon Arkansas's submitted RH SIP and our review of comments. 
As articulated in our proposed rulemaking and elsewhere in our response 
to comments, we find that the current permit limit (i.e. no additional 
controls) is PM BART for Entergy White Bluff Units 1 and 2 for both 
bituminous and sub-bituminous coal firing scenarios.
    Comment: The EPA cannot propose to disapprove the BART 
determination for SO2 for the Entergy White Bluff Units 1 
and 2 because the EPA did not evaluate the most recent and more 
detailed BART analysis conducted for Entergy's White Bluff facility 
when making its decision. The EPA's proposal references the 2006 BART 
analysis as the basis for EPA's decision on Arkansas's White Bluff BART 
determinations and not the 2008 revised BART analysis. The 2008 revised 
BART analysis considered additional non-air quality environmental 
impacts and provided a detailed BART five factor analysis. The 2008 
revised BART report was evaluated by ADEQ and provided to EPA. Even 
though EPA did not consider the 2008 revised BART analysis in its 
proposed rulemaking, it agreed with its findings in a 2009 letter to 
ADEQ staff that installation of dry scrubber technology is BART for the 
White Bluff facility. The EPA's lack of consideration of the most 
current and accurate BART analysis and determination for the White 
Bluff facility makes EPA's

[[Page 14647]]

proposed rule regarding the White Bluff facility inaccurate and 
arbitrary.
    Response: The EPA notes that the December 2006 White Bluff BART 
analysis is the BART analysis that was included in Appendix 9.3A of the 
Arkansas RH SIP received by EPA on September 23, 2008. As such, the 
December 2006 White Bluff BART analysis is what is before EPA to take 
action on. The EPA does not have the authority to take action on a SIP 
revision that has never been officially submitted by the State. The EPA 
is aware that in a letter dated August 8, 2008, sent by Entergy to 
ADEQ, the source requests that the 2008 revised BART analysis supersede 
the 2006 BART analysis.\182\ The EPA notes that the CAA places the 
authority and duty to submit SIPs on the states. Under the RH 
regulations, it is the State who is authorized to make BART 
determinations for inclusion in the RH SIP submitted to EPA. As such, 
even if a source submits a revised BART analysis to the State and 
requests that the revised version supersede the one currently in the RH 
SIP, EPA is not authorized to take action on the revision if the State 
does not adopt the revised version as a revision to the RH SIP, allow 
the FLM to review the proposed RH SIP revision at least 60 days prior 
to holding any public hearing, undergo reasonable notice and public 
hearing, and submit the revision to EPA in the context of an official 
SIP submission. This did not happen.
---------------------------------------------------------------------------

    \182\ Letter from Mark C. Bowles, Arkansas Environmental Support 
Manager, to Mike Bates, Air Division Chief, ADEQ, dated August 8, 
2008. Please see the docket for this rulemaking for a copy of this 
letter.
---------------------------------------------------------------------------

    While EPA did provide comments in a letter dated November 25, 2009, 
to the State on the 2008 revised BART analysis for White Bluff, this 
was done in the context of EPA's review of a draft Title V/Prevention 
of Significant Deterioration (PSD) permit for White Bluff.\183\ Since 
the draft Title V permit proposed by the State proposed to incorporate 
the control equipment proposed by Entergy in the 2008 revised BART 
analysis for White Bluff, the 2008 BART analysis was provided as an 
attachment to the proposed permit. Our review of the draft Title V 
permit did not involve a full review of the 2008 BART analysis, as we 
were only reviewing that BART analysis in the context of providing 
comments to the State on the draft Title V permit. In the comment 
letter EPA sent to the State, we did note that we agreed that dry 
scrubber technology is generally considered BART, but we also noted 
that we did not agree that the SO2 emission limit proposed 
by the source is reflective of the control efficiency this control 
technology is capable of achieving, and that we did not agree that this 
SO2 emission limit of 0.15 lb/MMBtu is BART. Our superficial 
review of the 2008 revised BART analysis also revealed that many of the 
same flaws we identified in our proposed rulemaking for the 2006 White 
Bluff BART analysis are also found in the 2008 White Bluff analysis. 
Furthermore, the draft Title V permit that proposed to incorporate the 
control equipment proposed by Entergy in the 2008 revised White Bluff 
BART analysis was never issued by the State.
---------------------------------------------------------------------------

    \183\ Letter from Jeff Robinson, Air Permits Chief, EPA Region 
6, to Tom Rheaume, Permits Branch Manager, ADEQ, dated November 25, 
2009.
---------------------------------------------------------------------------

    We disagree that our rulemaking regarding White Bluff Units 1 and 2 
is inaccurate and arbitrary because the EPA did not rely on the 2008 
revised White Bluff BART analysis, as the 2008 revised White Bluff BART 
analysis is not before EPA to take action on.
7. Other Comments Related to BART
    Comment: The EPA's proposed disapproval of BART for the Entergy 
White Bluff auxiliary boiler is legally incorrect because the unit is 
not BART eligible. The EPA disapproved ADEQ's BART determination that 
BART for the White Bluff auxiliary boiler is a restriction to operate 
no more than 4360 hours annually. However, the White Bluff auxiliary 
boiler has only a heat input capacity of 183 MMBtu/hr, which is less 
than the BART-eligible threshold of 250 MMBtu/hr. The BART Guidelines 
supports this finding that units which are located at a steam electric 
plant, but which themselves are not in any of the 26 BART source 
categories, such as the White Bluff auxiliary boiler, should not be 
considered BART-eligible. Further, the Guidelines state that for 
fossil-fuel boilers more than 250 MMBtu/hour heat input, this category 
includes only those boilers that are individually greater than 250 
MMBtu/hour heat input.
    Response: The EPA agrees that the Auxiliary Boiler (SN-05) at the 
Entergy White Bluff Plant does not fall into ``Category 2'' (i.e. 
fossil-fuel boilers of more than 250 million BTU/hr heat input) under 
the BART Guidelines. However, as noted in our proposed rulemaking, it 
does fall into ``Category 1'' (i.e. steam electric plants of more than 
250 million BTU/hr heat input) under the BART Guidelines. The BART 
Guidelines state the following regarding the BART eligibility of steam 
electric plants of more than 250 MMBTU/hr heat input:

    ``Because the category refers to `plants,' we interpret this 
category title to mean that boiler capacities should be aggregated 
to determine whether the 250 million BTU/hr threshold is reached. 
This definition includes only those plants that generate electricity 
for sale.'' \184\
---------------------------------------------------------------------------

    \184\ Appendix Y to Part 51, section II.A.

    The BART Guidelines also provide the following example to help 
states determine whether a boiler at a steam electric plant of more 
than 250 MMBtu/hr heat input falls into ``Category 1'' (i.e. steam 
electric plants of more than 250 million BTU/hr heat input) under the 
---------------------------------------------------------------------------
BART Guidelines:

    ``Example: A stationary source includes a steam electric plant 
with three 100 million BTU/hr boilers. Because the aggregate 
capacity exceeds 250 million BTU/hr for the `plant,' these boilers 
would be identified in Step 2.'' \185\
---------------------------------------------------------------------------

    \185\ Appendix Y to Part 51, section II.A.

    Therefore, even though the Auxiliary Boiler (SN-05) at the Entergy 
White Bluff Plant is individually only 183 MMBtu/hr, since it is 
located at a plant where the aggregate capacity exceeds 250 MMBtu/hr, 
the Auxiliary Boiler is BART eligible and, as explained in our proposed 
rulemaking, subject to BART. As such, our proposed disapproval of BART 
for the auxiliary boiler is consistent with the BART Guidelines and is 
legally correct. For the reasons articulated in our proposed 
rulemaking, we are finalizing our proposed disapproval of BART for the 
Auxiliary Boiler (SN-05) at the Entergy White Bluff plant.
    Comment: The EPA has not demonstrated in its proposed partial 
disapproval of Arkansas RH SIP that post-combustion controls are cost-
effective. The EPA has also not demonstrated that Arkansas's reliance 
on presumptive limits without analyzing post-combustion controls abused 
its authority to determine the appropriateness of the selected BART 
technologies.
    Response: The BART Guidelines provide that in identifying all 
options, you must identify the most stringent option as well as a 
reasonable set of options for analysis.\186\ The RHR also provides that 
in establishing source specific BART emission limits, the State should 
identify and consider in the BART analysis the maximum level of 
emission reduction that has been achieved in other recent retrofits at 
existing sources in the source category.\187\ The visibility 
regulations define BART as ``an emission limitation based on the degree 
of reduction achievable through the application of the best system of 
continuous emission

[[Page 14648]]

reduction.'' Since recent retrofits at existing sources provide a good 
indication of the current ``best system'' for controlling emissions, 
these controls must be considered in the BART analysis. As explained in 
our proposed rulemaking, post-combustion controls for NOX, 
SO2, and PM have been demonstrated to be technically 
feasible and cost-effective controls at fossil fuel fired EGUs that are 
similar to those that are subject to BART in Arkansas. As articulated 
in our proposed rulemaking (and also discussed elsewhere in our 
response to comments), EPA is also aware of at least one type of 
NOX post-combustion control (SNCR) that has been 
demonstrated to be technically feasible for a power boiler at a kraft 
pulp mill with similar design specifications as Domtar Ashdown Mill 
Power Boilers No. 1 and 2. Therefore, states must consider post-
combustion controls in their BART analyses for NOX, 
SO2, and PM if such controls have been recently installed as 
retrofits at existing sources in the source category.
---------------------------------------------------------------------------

    \186\ Appendix Y to Part 51, section IV.D.
    \187\ 64 FR 35740.
---------------------------------------------------------------------------

    Furthermore, our disapproval of some of Arkansas's BART 
determinations where the State did not consider post-combustion 
controls, is not based on a demonstration by EPA that post-combustion 
controls are cost-effective at any of Arkansas's subject to BART 
sources. Instead, it is based on our finding that some of the State's 
BART analyses did not satisfy the RHR and applicable EPA guidance. We 
did not perform a source specific BART analysis to determine if post-
combustion controls are cost-effective at Arkansas's subject to BART 
sources nor are we required to perform such an analysis in reviewing a 
SIP revision. As explained in our response to other comments and as 
required by CAA section 169A(g)(2) and 40 CFR 51.308(e)(1)(ii)(A), it 
is the State's responsibility to conduct a five factor BART analysis 
that satisfies the RHR and BART Rule using the NOX and 
SO2 presumptive emission limits as a starting point in the 
BART analysis. In addition, as explained above, states must consider 
post-combustion controls in their BART analyses for NOX, 
SO2, and PM if such controls are technically feasible. It is 
EPA's responsibility to review the adequacy of this analysis.
    Comment: The EPA's proposed disapproval is inconsistent with EPA's 
guidance and regulations concerning visibility protection causing 
regulatory uncertainty among the EGU industry. The EPA's proposed 
disapproval action should be withdrawn in favor of approval of the 
Arkansas RH SIP.
    Response: Because the comment is not specific about what aspect of 
our proposed disapproval is believed to be inconsistent with EPA 
guidance and RH regulations, it is not possible for EPA to address in 
this response any specific concerns. Several similar comments raised 
very specific concerns. Our responses to these can be found elsewhere 
in our responses to comments. As articulated in our proposed rulemaking 
and further explained in our responses to other comments, EPA's partial 
approval and partial disapproval of the Arkansas RH SIP is consistent 
with the CAA, the RHR, BART Rule, and EPA guidance. Since our 
rulemaking is consistent with the above, we disagree that it causes 
regulatory uncertainty among the EGU industry.
    Comment: Arkansas's BART determinations are consistent with the 
BART Guidelines and EPA should defer to the state's decision. Instead 
of deferring to the state's judgment about the necessary measures to 
implement BART within its borders, EPA proposed to substitute its 
judgment concerning what constitutes BART and what constitutes an 
acceptable LTS for making reasonable progress toward the national goal.
    Response: The EPA disagrees that all of Arkansas's BART 
determinations satisfy the CAA, the RHR, BART Rule, and EPA guidance. 
For some BART determinations, Arkansas adopted NOX and 
SO2 presumptive limits without conducting a source-specific 
analysis of appropriate levels of control when those sources have the 
capability of more stringent controls. This is in contradiction with 
the RHR and the BART Guidelines. We have determined that Arkansas's 
failure to conduct the BART analysis despite the evidence that the BART 
analysis might result in adoption of a different emissions limit was 
significant enough to result in BART determinations that were 
unreasoned and unjustified. Accordingly, those BART determinations, 
that adopted presumptive limits without conducting any additional BART 
analysis when information exists that may affect the BART 
determination, are not approvable. For some BART determinations, 
Arkansas did not perform a full BART analysis by not considering one or 
more factors it is required to consider in determining whether retrofit 
control should be required. We have determined that not considering one 
or more BART factors by Arkansas in its BART determinations, when it is 
demonstrable that this lack of analysis could alter the BART 
determination, is unreasoned and unsupportable. Thus, those BART 
determinations, which lack the consideration of one or more BART 
factors when it can be demonstrated that lack of consideration of the 
BART factor has the potential to alter the BART determination, are not 
approvable. We are also disapproving Arkansas's LTS because it does not 
satisfy the requirements under 40 CFR 51.308(d)(3) by relying on BART 
determinations that are inconsistent with the CAA and the RHR as 
detailed in our BART disapproval actions.\188\ As explained in our 
response to other comments, EPA agrees that States have broad authority 
and flexibility under the RHR. Furthermore, we are not substituting our 
judgment and forcing Arkansas to adopt any specific BART determination. 
Rather, we are disapproving portions of Arkansas's RH SIP that address 
BART, the LTS, and the RPGs because the State omitted critical analyses 
and made flawed assumptions that may compromise any decisions that 
arise from it. In doing so, the State did not satisfy the requirements 
of the CAA, RHR, and the BART Rule. The state could submit and EPA 
would approve RH SIP revisions that reached identical determinations as 
the current SIP submittal if Arkansas's analyses in reaching those 
determinations are consistent with the CAA, RHR, and BART Rule.
---------------------------------------------------------------------------

    \188\ 76 FR at 64186, at 64187.
---------------------------------------------------------------------------

    Comment: Because of the limited ability to combust fuel oil on a 
short-term basis for the Domtar Ashdown Mill Power Boiler No.1, a 
higher SO2 emission rate was proposed of 1.12 lb/MMBtu even 
though the average long-term emissions are low. The EPA is incorrect in 
stating that there is a mismatch between ADEQ's high BART 
SO2 emission limit and the emission needs of the Domtar 
Power Boiler No.1 when you take into account the actual operation of 
and the fuels used by the boiler.
    Response: As articulated in our proposed rulemaking, as part of its 
BART analysis, the State should have conducted a fuel inventory for 
Domtar Power Boiler No. 1 and investigated sources of potential sulfur 
emissions. If the source believes that burning fuel oil on a relatively 
long-term basis is the primary source of high SO2 emissions 
from Domtar Power Boiler No. 1, the State should consider in its BART 
analysis establishing a limit on the sulfur content of the fuel oil 
burned at the boiler and/or lowering the limit of fuel oil usage. In 
addition, if the boiler operator wishes to burn fuel oil on a long-term 
basis and this is the primary source of SO2 emissions from 
the boiler, the State should evaluate SO2 post-

[[Page 14649]]

combustion controls in its BART analysis. A proper BART evaluation of 
SO2 controls may demonstrate that the installation and 
operation of an SO2 scrubber is cost-effective and would 
result in significant visibility improvement.
    Comment: With regard to the evaluation of upgrades to the existing 
scrubber at Domtar's Power Boiler No. 2, multiple scrubber upgrades 
were considered including the addition of a spray tower and/or a third 
scrubber. Preliminary estimates of capital costs for the third scrubber 
exceed $10 million not taking into account the expenses of installing 
the technology in a limited space. Considering Arkansas's progress 
towards the overall goal of the RH program, such costs are clearly not 
justified.
    Response: As articulated in our proposed rulemaking, the BART 
Guidelines provide that if a state determines that a source has 
controls already in place that are the most stringent controls 
available and that all possible improvements to any control devices 
have been made, it may take a streamlined approach for the BART 
analysis for this source. Since the source has an existing wet scrubber 
for control of SO2 emissions, Arkansas has elected to take 
this streamlined approach for Power Boiler No.2. As explained in our 
proposed rulemaking, we agree that SO2 post-combustion 
controls are typically the most stringent technology available for 
control of SO2. However, we disagree that a BART emission 
limit of 1.2 lb/MMBtu for SO2 is reflective of the most 
stringent controls available. Further, the State has not provided 
sufficient documentation of the upgrades considered for the existing 
wet scrubber. In addition, based on the information available, it also 
appears that the State has not considered all possible improvements to 
the scrubber. As articulated in our proposed rulemaking, the BART 
Guidelines state that there are numerous scrubber enhancements 
available to upgrade the average removal efficiencies of all types of 
existing scrubber systems, including increasing a scrubber system's 
reliability (and conversely decreasing its downtime) by way of 
optimizing operational procedures, improving maintenance practices, 
adjusting scrubber chemistry, and increasing auxiliary equipment 
redundancy.\189\ The BART Guidelines also provide the following 
detailed list of potential scrubber upgrades that have been proven in 
the industry as cost-effective means to increase overall SO2 
removal of wet systems:
---------------------------------------------------------------------------

    \189\ Appendix Y to Part 51, section IV.E.4.
---------------------------------------------------------------------------

     Elimination of Bypass Reheat
     Installation of Liquid Distribution Rings
     Installation of Perforated Trays
     Use of Organic Acid Additives
     Improve or Upgrade Scrubber Auxiliary System Equipment
     Redesign Spray Header or Nozzle Configuration
    Based on the limited information that has been provided to EPA, it 
does not appear that the State has evaluated all possible improvements 
to the existing wet scrubber at Domtar Ashdown Mill Power Boiler No. 2. 
Therefore, the State must either consider all possible improvements to 
the existing wet scrubber (including proper documentation of these) or 
conduct a full five factor BART analysis that satisfies the 
requirements of the RHR and the BART Rule for Power Boiler No. 2. EPA 
is finalizing our proposed disapproval of the State's SO2 
BART determination for the Domtar Power Boiler No. 2.
    Comment: The EPA should not question if the proposed SO2 
BART limit of 1.2 lb/MMBtu represents 90% control for Domtar's Power 
Boiler No. 2. The 90% control value has never been confirmed via 
testing. Rather this control efficiency was estimated based on a 
comparison of the actual maximum daily emissions measured via CEMS and 
the uncontrolled emission rate predicted by EPA's AP-42 data. It may be 
overestimated, but the percent control value is somewhat irrelevant due 
to the BART limit on a lb/MMBtu basis.
    Response: As articulated in our proposed rulemaking, we agree that 
SO2 post-combustion controls are typically the most 
stringent technology available for control of SO2. However, 
we disagree that a BART emission limit of 1.2 lb/MMBtu for 
SO2 is necessarily reflective of the most stringent controls 
available. Since Arkansas has elected to take the streamlined approach 
for the SO2 BART analysis for this source, it must ensure 
that the source has controls already in place that are the most 
stringent controls available and that all possible improvements to any 
control devices have been made. This has not been done. Since the State 
is relying on the fact that the source has the most stringent controls 
in place to take a streamlined approach to the BART analysis, we 
disagree that the control efficiency of the existing wet scrubber is 
irrelevant. As explained elsewhere in our response to comments, the 
State must either ensure it has the most stringent controls in place 
and consider all possible improvements to the existing wet scrubber 
(including proper documentation of these) or conduct a five factor BART 
analysis that satisfies the requirements of the RHR and the BART Rule 
for Domtar Power Boiler No. 2. EPA is finalizing our proposed 
disapproval of the State's SO2 BART determination for 
Domtar's Power Boiler No. 2.
    Comment: Since EPA is proposing to partially approve and partially 
disapprove portions of the Arkansas SIP, EPA should clarify that the 
compliance dates are all based on the same final approval date of the 
entire SIP. Compliance should be five years after final approval by 
EPA.
    Response: The EPA disagrees that compliance with the BART 
requirements is contingent upon full approval of the entire Arkansas RH 
SIP. 40 CFR 51.308(e)(iv) requires subject to BART sources to install 
and operate BART as expeditiously as practicable, but in no event later 
than 5 years after the approval of the implementation plan revision. 
Therefore, in the event of a partial approval of the RH SIP, those 
sources whose BART determinations for a particular pollutant have been 
approved by EPA are required to install BART as expeditiously as 
practicable, but in no event later than 5 years after the partial 
approval of the BART determination. The RH regulatory language in no 
way conditions the BART compliance dates on EPA's full approval of the 
entire RH SIP.
    Comment: Arkansas did a proper BART evaluation for Entergy Lake 
Catherine Unit 4 and White Bluff Units 1 and 2 when it adopted the 
presumptive limits. Arkansas did the BART five factor analyses, which 
is consistent with the BART Guidelines. EPA's proposed disapproval of 
Arkansas's NOX and SO2 BART determinations for 
Entergy's White Bluff and Lake Catherine facilities is based on EPA's 
incorrect evaluation of Arkansas's BART analyses and prioritizes EPA's 
disagreements with Arkansas concerning available technologies and the 
associated costs of compliance over the visibility protection program's 
fundamental purpose of remedying visibility impairment by 2064, which 
the Arkansas's RH SIP achieves. The EPA's disapproval for Arkansas's 
BART determinations for Entergy Lake Catherine and White Bluff 
facilities is a disagreement with the results of the BART determination 
as to the appropriate level of control for the Lake Catherine and White 
Bluff facilities. Accordingly, EPA should withdraw its proposed partial 
disapproval and approve the existing Arkansas RH SIP.

[[Page 14650]]

    Response: As explained in our proposed rulemaking,\190\ we disagree 
that Arkansas did a proper five factor BART evaluation for 
NOX and SO2 BART when it adopted the presumptive 
limits for White Bluff Units 1 and 2, and we also disagree that 
Arkansas did a proper five factor BART evaluation for NOX 
BART (natural gas and fuel oil firing) and SO2 and PM BART 
(fuel oil firing) for Lake Catherine Unit 4. We do note that in our 
proposed rulemaking on the Arkansas RH SIP, we proposed to find that 
Arkansas did not appropriately consider the costs of controls when they 
assumed a 10% capacity factor for Lake Catherine Unit 4 and an 85% 
capacity factor for White Bluff Units 1 and 2. Based on comments 
received during the public comment period, we have found that we made 
an error in proposed rulemaking in our calculation of the historical 
capacity factors for these units. We agree that assuming a 10% capacity 
factor for Lake Catherine and an 85% capacity factor for White Bluff 
Units 1 and 2 in the calculation of emissions reductions achieved and 
cost of controls is appropriate and in accordance with the BART 
Guidelines (see our response to similar comments for a more detailed 
explanation).
---------------------------------------------------------------------------

    \190\ EPA notes that in our proposed rulemaking on the Arkansas 
RH SIP, we proposed to find that Arkansas did not appropriately 
consider the costs of controls when they assumed a 10% capacity 
factor for Lake Catherine Unit 4 and an 85% capacity factor for 
White Bluff Units 1 and 2. Based on comments received during the 
public comment period, we have found that we made an error in 
proposed rulemaking in our calculation of the historical capacity 
factors for these units. We agree that assuming a 10% capacity 
factor for Lake Catherine and an 85% capacity factor for White Bluff 
Units 1 and 2 in the calculation of emissions reductions achieved 
and cost of controls is appropriate and in accordance with the BART 
Guidelines (see our response to other comments in our response to 
comments for a more detailed explanation). However, we still find 
that Arkansas did not appropriately consider a number of factors (as 
articulated in our proposed rulemaking and explained elsewhere in 
our response to comments) in its five factor BART analysis for 
NOX BART (natural gas and fuel oil firing), and 
SO2 and PM (fuel oil firing) BART for Lake Catherine Unit 
4, and for NOX and SO2 BART (bituminous and 
sub-bituminous coal firing) for White Bluff Units 1 and 2. 
Therefore, we are finalizing our disapproval of BART for the 
aforementioned pollutants and units.
---------------------------------------------------------------------------

    However, we still find that Arkansas did not appropriately consider 
a number of factors (as articulated in our proposed rulemaking and 
explained elsewhere in our response to comments) in its five-factor 
BART analysis for NOX BART (natural gas and fuel oil 
firing), and SO2 and PM (fuel oil firing) BART for Lake 
Catherine Unit 4, and for NOX and SO2 BART 
(bituminous and sub-bituminous coal firing) for White Bluff Units 1 and 
2. The State's BART analyses for Lake Catherine Unit 4 and White Bluff 
Units 1 and 2 for the aforementioned pollutants do not satisfy all the 
requirements of the RHR and BART Guidelines. As such, our disapproval 
of the BART determinations for Lake Catherine Unit 4 and White Bluff 
Units 1 and 2 is not based on our disagreement with the results of the 
BART determination as to the appropriate level of control for the Lake 
Catherine and White Bluff facilities. Instead, our disapproval is based 
on our finding that Arkansas's BART analyses for these units and 
pollutants do not satisfy all the requirements of the RHR and BART 
Guidelines. The State omitted critical analyses and made flawed 
assumptions that compromise the resulting BART determinations. As such, 
until a proper five-factor BART analysis is conducted for these 
pollutants that satisfies all the statutory and regulatory RH 
requirements and adheres to the applicable guidelines, it will not be 
possible to know whether the level of control adopted by the State or a 
different level of control is BART for these units and pollutants. The 
state could submit and EPA would approve RH SIP revisions that reached 
identical determinations as the current SIP submittal if Arkansas's 
analysis in reaching those determinations is consistent with the RHR 
and applicable EPA Guidance. As explained elsewhere in our response to 
comments, even if the CENRAP's modeling shows that the State is 
expected to meet the URP for the first implementation period ending in 
2018 and is projected to meet the natural visibility goal by 2064 if 
the same level of visibility improvement expected to take place during 
the first implementation is achieved for every remaining implementation 
period, the State of Arkansas has not satisfied all its BART 
requirements. We are finalizing our disapproval of BART for 
NOX (natural gas firing and fuel oil firing) and 
SO2 and PM (fuel oil firing) for Lake Catherine Unit 4 and 
BART for NOX and SO2 (bituminous and sub-
bituminous coal firing) for White Bluff Units 1 and 2.
    Comment: It appears that EPA agrees with the State's approach of 
developing BART determinations for each fuel-burning scenario for 
subject to BART units that are permitted to burn more than one type of 
fuel. Setting separate, individual BART limits for each fuel type that 
a source is physically capable of burning and permitted to burn is a 
generally reasonable approach to addressing multi-fuel units. Other 
approaches may also be reasonable if chosen by the State, so long as 
they do not amount to a redefinition of the source, as would occur if 
use of a particular fuel-type, otherwise permitted, were prohibited or 
made infeasible as a result of the imposition of a BART limit.
    Response: The EPA generally agrees with the State's approach of 
developing BART determinations for each fuel burning scenario for 
subject to BART sources that are permitted to burn more than one type 
of fuel, as was done for Entergy Lake Catherine Unit 4 and Entergy 
White Bluff Units 1 and 2. There is nothing in the RHR or the BART 
Guidelines prohibiting a State from doing so. Although the BART 
Guidelines provide that we do not consider BART as a requirement to 
redesign the source when considering available control 
alternatives,\191\ we do note that if a State considers it appropriate, 
it may consider a fuel switch (i.e. switch from burning fuel oil to 
natural gas), which does not necessarily constitute a redesign of the 
source, as one of the options in the BART analysis for a particular 
source. This was done by the State of Kansas, which determined that a 
switch from fuel oil to natural gas satisfied the BART requirements for 
SO2 and NOX for Westar Energy Gordon Evans Unit 2 
(the unit can burn both fuel oil and natural gas).\192\ The EPA 
approved Kansas' aforementioned BART determination.
---------------------------------------------------------------------------

    \191\ Appendix Y to Part 51, section IV.D.1.
    \192\ 76 FR 52604 and 76 FR 80754.
---------------------------------------------------------------------------

    Comment: As stated by EPA in its proposed action on the Arkansas RH 
SIP, neither AEP nor ADEQ performed a five-factor BART analysis for 
Flint Creek Boiler No. 1 (76 FR 64203). The company commented that 
since it was proposing to meet the presumptive BART limits for 
SO2 and NOX, it did not need to undertake a five-
factor BART analysis. This does not constitute a proper BART analysis, 
and EPA was right in proposing disapproval of Arkansas's SO2 
and NOX BART requirements for Flint Creek. The presumptive 
limits in EPA's BART Guidelines do not exempt a source from a five-
factor BART analysis. If ADEQ or AEP-SWEPCO had performed a five-factor 
analysis for Flint Creek, the BART limits would likely have been lower 
than 0.15 lbs/MMBtu for SO2 and 0.23 lbs/MMBtu for 
NOX.
    Response: As explained elsewhere in this final rulemaking, we are 
finalizing our proposed disapproval of BART for NOX and 
SO2 for Flint Creek Boiler No. 1 because the State did not 
conduct a five factor BART analysis for the source.
    Comment: The SO2 and NOX emission limits for 
Flint Creek Boiler No. 1 do not reflect the best system of continuous

[[Page 14651]]

SO2 and NOX emission reduction and EPA cannot 
find that these emission limits satisfy the legal BART requirements 
without a five-factor BART analysis. The proposed SO2 BART 
limit of 0.15 lbs/MMBtu for Flint Creek reflects only 67% removal from 
the uncontrolled 2010 average annual SO2 emission rate of 
0.46 lbs/MMBtu. The best system of continuous SO2 emission 
reductions is a wet scrubber, which can achieve 95-99% removal. The 
next best system of continuous SO2 emissions reductions is a 
dry scrubber, which can achieve 90-95% SO2 removal. EPA 
recently proposed and finalized as a FIP the installation of dry 
scrubbers as BART at six coal-fired EGUs in Oklahoma to achieve the 
SO2 BART emission limit of 0.6 lbs/MMBtu on a 30-day rolling 
average basis. The Oklahoma units are all similar to Flint Creek in 
size and coal type. This provides evidence that had a proper five 
factor BART analysis been done for Flint Creek, the SO2 BART 
limit would have been lower than 0.15 lb/MMBtu. Similarly, a five-
factor analysis for NOX at Flint Creek would have required 
the evaluation of SCR and SNCR, which can achieve NOX 
emission limits lower than 0.23 lbs/MMBtu. If SCR had been evaluated as 
BART for NOX, emissions would have been 78% lower, providing 
significant benefits to the State's Class I areas. NOX BART 
emission limits as low as 0.5 lb/MMBtu have been promulgated (76 FR 
52390, 52439).
    Response: The EPA agrees that we cannot approve the State's BART 
determinations for SO2 and NOX for Flint Creek 
Boiler No. 1 because the State adopted presumptive limits as meeting 
BART for the source without conducting a BART five-factor analysis. The 
EPA also believes that a proper evaluation of the five statutory 
factors is likely to demonstrate that emission limits lower than the 
NOX and SO2 presumptive emission limits are BART 
for Flint Creek Boiler No. 1. We are finalizing our proposed 
disapproval of the State's BART determinations for SO2 and 
NOX for Flint Creek Boiler No. 1.
    With regard to the comment that a wet scrubber is the ``best system 
of continuous emissions reductions'' for SO2 and a dry 
scrubber is the next ``best system of continuous emissions reductions'' 
for SO2, we note that 40 CFR 51.308(e)(1)(ii)(B) directs 
States to identify the ``best system of continuous emissions control 
technology'' taking into account ``the technology available, the costs 
of compliance, the energy and non-air quality environmental impacts of 
compliance, any pollution control equipment in use at the source, and 
the remaining useful life of the source.'' Therefore, while we agree 
that a wet scrubber and a dry scrubber are generally the two most 
stringent control technologies available for control of SO2 
emissions and have been found to be BART for many sources, we disagree 
that a wet scrubber or a dry scrubber will necessarily be BART in every 
case.
    Comment: The EPA's proposal is correct that the White Bluff BART 
analyses for SO2 and NOX in the Arkansas RH SIP 
are incomplete and inadequate because the company only evaluated 
options to comply with the presumptive BART limits rather than 
evaluating emission limits reflective of the best system of continuous 
emission reduction at White Bluff Units 1 and 2. In Entergy's 2006 BART 
analysis, which is part of the Arkansas RH SIP, the company did not 
explain why it proposed a 0.15 lb/MMBtu SO2 emission limit 
for either a wet scrubber or a dry scrubber, when the higher control 
efficiency associated with a wet scrubber would result in the ability 
to meet a lower SO2 emission limit. Also, the proposed 
SO2 BART limit of 0.15 lb/MMBtu only reflects approximately 
80% control from the base case SO2 emission rates, and not 
the 95% and 92% control efficiency capable of being achieved by a wet 
and dry scrubber, respectively. Entergy's 2006 BART analysis did note 
that the resulting SO2 emission limit from either control 
technology would ``depend on the future coal sulfur content'' (see 
Appendix 9.3 of Arkansas RH SIP). Entergy's revised 2008 BART analysis, 
which has not been adopted by Arkansas or submitted to EPA as a RH SIP 
revision, elaborated on this, explaining that 2 lb/MMBtu SO2 
is assumed as the highest coal sulfur content for dry scrubbing and 3 
lb/MMBtu is assumed for wet scrubbing. Taking into account Entergy's 
projected future coal sulfur content (which varies depending on the 
control technology used) and Entergy's claimed percent removal 
efficiencies for the control technologies considered, the resulting 
emission limit just happens to equal EPA's presumptive BART limit for 
SO2 of 0.15 lb/MMBtu. White Bluff is not authorized to burn 
coal of unlimited sulfur or ash content, and the higher uncontrolled 
coal sulfur content that Entergy assumed in its December 2006 BART 
analysis (as well as in its revised 2008 BART analysis) is prohibited 
from being utilized at the White Bluff units under the terms of the 
White Bluff permit. It would be virtually impossible for White Bluff to 
comply with Permit Condition IV.6 in its Title V permit and burn coal 
with uncontrolled SO2 emissions at the inlet to the scrubber 
of 2 lb/MMBtu, much less 3 lb/MMBtu. The future uncontrolled 
SO2 emission rate must not be raised above the level of 
uncontrolled SO2 emissions/coal sulfur content authorized by 
the White Bluff permit and EPA must make clear that the assumed 
uncontrolled SO2 emission rate cannot be improperly inflated 
in proposing a BART emission limitation. EPA has commented on the BART 
determinations of the Wisconsin Department of Natural Resources as well 
as other states that BART cannot be based on characteristics of coal 
that might be burned in the future (see Exhibit 18). Instead, it is to 
be based on the fuel characteristics during the base case. If Entergy 
plans to burn higher sulfur coal in the future as compared to that 
utilized in the base case, that must be made clear in the BART analysis 
because sulfur content of coal should be considered in determining 
whether it is most beneficial to install a wet scrubber or a dry 
scrubber.
    Response: The EPA agrees that in its SO2 BART analysis 
for White Bluff Units 1 and 2, the State did not explain why it 
proposed a 0.15 lb/MMBtu SO2 emission limit for either a wet 
scrubber or a dry scrubber, when the higher control efficiency 
associated with a wet scrubber would result in the ability to meet a 
lower SO2 emission limit. EPA also agrees that the State's 
proposed SO2 BART limit of 0.15 lb/MMBtu only reflects 
approximately 80% control from the base case SO2 emission 
rates, and not the 95% and 92% control efficiency capable of being 
achieved in many cases by a wet and dry scrubber, respectively. EPA 
also agrees that the BART Guidelines provide that BART must be based on 
the fuel characteristics during the base case. If a source projects 
that future operating parameters (i.e. limited hours of operation or 
capacity utilization, type of fuel, raw materials or product mix or 
type) will differ from past practice, resulting in greater (or less) 
emissions, the State must make this clear in the BART evaluation, as it 
may have an impact on the cost analysis and the ultimate selection of 
BART. Since the State did not properly document the cost of the 
SO2 control options considered in the BART analysis 
(including a reasonably detailed line by line breakdown of costs), we 
were not able to determine if the parameters assumed in the State's 
cost analysis for White Bluff Units 1 and 2 are reflective of the base 
case. As explained elsewhere in this final rulemaking, we are 
finalizing our proposed disapproval of SO2 BART for

[[Page 14652]]

Entergy White Bluff Units 1 and 2 for both the bituminous and sub-
bituminous coal firing scenarios.
    Comment: The EPA's proposed disapproval of the SO2, 
NOX, and PM BART determinations for fuel oil firing for 
Entergy Lake Catherine Unit 4 is correct because Entergy's BART 
analyses for the fuel oil firing scenario are inadequate. Neither 
Entergy nor ADEQ considered and evaluated post-combustion controls for 
the fuel oil firing scenario, and Entergy improperly assumed only a 10% 
capacity factor in the cost-effectiveness calculations, even though the 
unit's capacity factor is not limited by any enforceable requirement. 
The EPA is also correct in not allowing the unit to be exempt from BART 
for the fuel oil firing scenario until the Lake Catherine permit is 
revised to prohibit Unit 4 from burning fuel oil.
    Response: The EPA agrees that the State did not evaluate any 
SO2 post-combustion controls and did not properly evaluate 
NOX post-combustion controls for Entergy Lake Catherine Unit 
4 for the fuel oil firing scenario.
    Based on comments received during the public comment period, it has 
come to our attention that we made an error in our calculation of the 
capacity factor for recent years for Lake Catherine Unit 4. Based on 
the information provided, we agree that the source has historically 
operated at less than a 10% capacity factor. The BART Guidelines 
provide that for the purpose of calculating the cost of controls, the 
State may calculate baseline emissions based upon continuation of past 
practice.\193\ However, as explained in more detail in our response to 
other comments and in our proposed rulemaking, we find that the State 
did not properly document the cost analysis for NOX, 
SO2, and PM controls for fuel oil firing for Entergy Lake 
Catherine Unit 4 because the proper documentation necessary to allow us 
to make an informed and proper evaluation of the BART analysis was not 
included in the SIP, as the BART Guidelines require.
---------------------------------------------------------------------------

    \193\ Appendix Y to Part 51, section IV.4.
---------------------------------------------------------------------------

    Therefore, we are finalizing our proposed disapproval of BART for 
NOX for both the natural gas and fuel oil firing scenarios, 
and SO2 and PM for the fuel oil firing scenario.
    Comment: The EPA's proposed disapproval of Arkansas's BART 
determinations for SO2, NOX, and PM for AECC's 
Bailey Unit 1 and McClellan Unit 1 is correct. ADEQ must comply with 
the requirement that once a unit is determined to be subject to BART, a 
BART determination must be made for all pollutants emitted by the 
source (see 40 CFR part 51, Sec.  51.301 and Appendix Y, section IV.A). 
EPA must also disapprove the PM BART requirements because there was no 
determination of BART for PM2.5.
    Response: While we are finalizing our proposed disapproval of the 
State's BART determinations for SO2, NOX, and PM 
for AECC's Bailey Unit 1 and McClellan Unit 1, we disagree that we must 
disapprove the PM BART determination because the State did not make a 
BART determination for PM2.5. The BART Guidelines do not 
specify that States must establish a BART limit for both 
PM10 and PM2.5. The BART Guidelines provide the 
following:
    ``You must look at SO2, NOX, and direct 
particulate matter (PM) emissions in determining whether sources cause 
or contribute to visibility impairment, including both PM10 
and PM2.5.'' \194\
---------------------------------------------------------------------------

    \194\ Appendix Y to Part 51, section III.A.2.
---------------------------------------------------------------------------

    This language in the BART Guidelines was intended to clarify to 
States that when determining whether a source is subject to BART, the 
modeling evaluation to determine the source's impact on visibility has 
to account for both PM10 and PM2.5 emissions. 
There are several instances in which we state in both the preamble to 
the RHR, and in the BART Guidelines that PM10 may be used as 
indicator for PM2.5 in determining whether a source is 
subject to BART. Neither the RHR nor the BART Guidelines specify that 
States must make separate BART determinations for PM10 and 
PM2.5. Therefore, we disagree that we must disapprove the PM 
BART determination for AECC's Bailey Unit 1 and McClellan Unit 1 on the 
basis that a BART determination for PM2.5 was not made.
    Comment: The EPA's proposed disapproval of the SO2 and 
NOX BART determinations for the Domtar Power Boilers No. 1 
and 2 the EPA's proposed disapproval of the PM BART determination for 
Domtar Power Boiler No. 2 are correct for the reasons given by EPA in 
its proposed rulemaking (76 FR 64207-210).
    Response: Consistent with the comment, we are finalizing our 
proposed disapproval of the State's SO2 and NOX 
BART determinations for the Domtar Power Boilers No. 1 and 2 and the 
State's PM BART determination for Domtar Power Boiler No. 2
    Comment: There is significant interest in the application of 
appropriate BART requirements for the Flint Creek Power Plant, the 
White Bluff Steam Electric Station, the AECC Carl E. Bailey Generating 
Station, and the AECC John L. McClellan Generating Station. It is 
critical to ensure that ratepayers are not burdened by improper and/or 
unnecessary requirements. EPA's proposed rule will impose unnecessary 
and/or improper costs and requirements on these and other Arkansas 
facilities. ADEQ's original RH SIP submission fully met the 
requirements of the CAA and its implementing regulations.
    Response: We disagree that our final action will impose unnecessary 
and improper requirements on Arkansas's subject to BART sources. In 
fact, for the BART determinations we are disapproving, we are not 
imposing or requiring a specific BART emission limit or cost. As 
explained elsewhere in our response to comments, our partial 
disapproval of Arkansas's RH SIP is a proper exercise of our authority 
under the CAA. Our role is to review the RH SIP submittal and determine 
if the state met the applicable statutory and regulatory requirements. 
When reviewing state SIPs, we must consider not only whether the State 
considered the appropriate factors in making decisions but also whether 
it acted reasonably in doing so. Some of Arkansas's BART determinations 
for its subject to BART sources, among other portions of the RH SIP, 
were not developed in accordance with the RHR and the BART Guidelines, 
as discussed in our proposed rulemaking and elsewhere in this final 
rulemaking. We are not imposing additional requirements beyond what the 
RHR and the BART Guidelines require. Therefore, we disagree that our 
proposed rulemaking, as finalized in this rulemaking, imposes 
unnecessary requirements on Arkansas's subject to BART sources.
    Comment: Since limiting the sulfur content of fuel oil to 1.0% by 
weight at the Bailey Unit 1 and McClellan Unit 1 is cost-effective and 
post-control modeling predicted that visibility impacts to Class I 
areas would be below the 0.5 dv contribution threshold, this control 
option was selected as BART. It is unnecessary to perform additional 
analyses for lower sulfur fuel oil for Bailey Unit 1 and McClellan Unit 
1.
    Response: While we agree that limiting the sulfur content of fuel 
oil to 1.0% by weight at the AECC Bailey Unit 1 and McClellan Unit 1 is 
extremely cost-effective ($54.90/ton SO2 removed for Bailey 
Unit 1 and $158.60/ton SO2 removed for McClellan Unit1), we 
find that it is very likely that other options that would result in 
greater visibility improvement may also be found to be cost effective. 
According to the Arkansas RH SIP, the post-control modeling 
demonstrates that with the SO2 BART controls selected by the 
State for AECC Bailey Unit 1, the visibility

[[Page 14653]]

impact would be 0.897 dv at Caney Creek, 0.574 dv at Upper Buffalo, 
0.809 dv at Hercules Glades, and 0.766 dv at Mingo.\195\ According to 
the Arkansas RH SIP, the post-control modeling demonstrates that with 
the SO2 BART controls selected by the State for AECC 
McClellan Unit 1, the visibility impact would be 1.011 at Caney Creek 
and 0.487 dv at Upper Buffalo.\196\ We note this constitutes 
approximately a 50% improvement in visibility across all areas. As 
such, if Arkansas conducts a proper five factor BART analysis that 
considers all five statutory factors and evaluates more stringent 
controls, such as a 0.5% or lower limit for the sulfur content of fuel 
oil used, Arkansas may find one or more of these more stringent 
controls to be cost-effective and result in even more visibility 
improvement than that resulting from the control option it selected. As 
explained in our proposed rulemaking, the visibility regulations define 
BART as ``an emission limitation based on the degree of reduction 
achievable through the application of the best system of continuous 
emission reduction.'' Since recent retrofits at existing sources 
provide a good indication of the current ``best system'' for 
controlling emissions, these controls must be considered in the BART 
analysis. The BART Guidelines provide that in identifying all options, 
States must identify the most stringent option (i.e. maximum level of 
control each technology is capable of achieving) as well a reasonable 
set of options for analysis.\197\ The RHR states that in establishing 
source specific BART emission limits, the State should identify and 
consider in the BART analysis the maximum level of emission reduction 
that has been achieved in other recent retrofits at existing sources in 
the source category.\198\ Fuel oil with a sulfur content of 0.5% by 
weight or less is being utilized in industry. In considering use of 
fuel oil with low sulfur content as a control option in the BART 
analysis, AECC did not identify and consider the maximum level of 
control achievable from the use of low sulfur fuel oil, and therefore, 
did not satisfy the RHR requirements.
---------------------------------------------------------------------------

    \195\ See Table 9.4b of the Arkansas RH SIP. Note that the pre 
and post control visibility impact shown on Table 9.4b is the 
modeled maximum visibility impact at each affected Class I area. As 
explained in our proposed rulemaking, the original meteorological 
databases generated by CENRAP did not include observations as EPA 
guidance recommends. Therefore, in their evaluation to determine if 
a source exceeds the 0.5 dv contribution threshold at nearby Class I 
areas, states used the 1st high values (i.e. maximum value) of 
modeled visibility impacts instead of the 8th high values (i.e. 98th 
percentile value). The use of the 1st high modeled values was agreed 
to by EPA, representatives of the Federal Land Managers, and CENRAP 
stakeholders.
    \196\ See Table 9.4c of the Arkansas RH SIP. Note that that the 
pre and post control visibility impact shown on Table 9.4c is the 
modeled maximum visibility impact at each affected Class I area.
    \197\ Appendix Y to Part 51, section IV.
    \198\ 64 FR 35740.
---------------------------------------------------------------------------

    In addition, as pointed out in the TSD for our proposed rulemaking 
on the Arkansas RH SIP, even though the State's cost analysis showed 
that wet scrubbers are cost-effective ($2,108.25/ton SO2 
removed and $1,658.32/ton SO2 removed), Arkansas did not 
evaluate the visibility impact of this control option. As explained in 
more detail elsewhere in our response to comments, the BART Guidelines 
require a State to evaluate all five statutory factors before 
eliminating a particular control option for BART.\199\ As articulated 
in our proposed rulemaking on the Arkansas RH SIP, the State must 
perform a cost analysis in which all cost estimates are properly 
documented and must evaluate the visibility impacts of all technically 
feasible control options considered before making a BART determination. 
This was not done in Arkansas's SO2 BART analysis for the 
AECC Bailey Unit 1 and McClellan Unit 1. As such, the BART analysis for 
SO2 for AECC Bailey Unit 1 and McClellan Unit 1 does not 
satisfy the RHR and CAA requirements.
---------------------------------------------------------------------------

    \199\ 70 FR 39130 and 39131.
---------------------------------------------------------------------------

    Therefore, we believe that it is necessary for Arkansas to perform 
additional analyses to evaluate the cost and visibility impact of using 
lower sulfur fuel oil at Bailey Unit 1 and McClellan Unit 1. It must 
also evaluate the visibility impact of wet scrubbers and any other 
control options considered in the BART analysis before making a BART 
determination.
    Comment: The results of the initial BART modeling performed in 
2006, which was cumulative modeling of SO2, NOX, 
and PM, indicated that both the AECC Bailey Unit 1 and McClellan Unit 1 
cause visibility impacts at one or more Class I areas. Pollutant-
specific modeling was then performed and the results of the pollutant-
specific modeling for NOX were all less than 0.5 dv, 
demonstrating that NOX neither caused nor contributed to 
visibility impacts. For this reason, a NOX engineering 
analysis was unnecessary and not performed. The EPA previously had an 
opportunity to comment on this issue about two years prior to ADEQ 
submitting its draft SIP to EPA, when ADEQ forwarded a question to EPA 
in an email dated October 19, 2006, asking whether or not five factor 
analyses were required for NOX and PM since both pollutants 
showed no impacts. No response to the question was ever received by 
ADEQ from EPA.
    Response: While we regret any kind of miscommunication or lapse of 
communication that may have occurred between us and Arkansas, we note 
that it is ultimately the State's duty to make sure that its RH SIP 
satisfies all the regulatory and statutory requirements and is 
consistent with all applicable EPA guidance. As explained elsewhere in 
our response to comments, the pollutant-specific analysis approach for 
NOX and SO2 used to evaluate controls at these 
AECC units does not take into consideration the chemical interaction 
between these two pollutants and ammonia present in the atmosphere. A 
reduction in sulfate emissions, while most likely reducing visibility 
impairment overall, can result in an increase in visibility impairment 
from nitrate due to the increase in ammonia available to react with 
nitrate to form visibility impairing aerosol. The pre-control modeling 
results indicate that nitrate is a significant contributor to 
visibility impairment on some days and this contribution can increase 
under conditions of decreased SO2 emissions. Therefore, 
NOX and SO2 emissions should be modeled together 
and emission control technologies should be evaluated for both 
pollutants. We are finalizing our proposed disapproval of the State's 
NOX, SO2, and PM BART determinations of the AECC 
Bailey Unit 1 and McClellan Unit 1.
    Comment: We do not agree with EPA's proposed approval of no BART 
determination for SO2 for the gas-firing scenario for 
Entergy Lake Catherine Unit 4 (76 FR 64203-204). Once a source is 
determined to be subject to BART, a BART determination must be made for 
all pollutants emitted by the source (see 40 CFR part 51, Sec.  51.301 
and appendix Y, section IV.A). Since the unit emits some SO2 
when firing gas, it must be subject to a BART limit. EPA cannot exempt 
the unit from an SO2 BART analysis when firing natural gas 
just because SO2 emissions are considered to be low when 
combusting such fuel. A BART analysis may show that the SO2 
limit currently in the Lake Catherine Title V permit satisfies BART, 
but that will not be known until a BART analysis is done.
    Response: In our review of the Arkansas RH SIP, we evaluated the 
determination by ADEQ that SO2 emissions when burning 
natural gas are very low and that no additional SO2 controls 
are required at Entergy Lake Catherine Unit 4. Furthermore, the 
modeling results submitted by Arkansas in Appendix 9.2B of the Arkansas 
RH SIP indicate that under natural gas firing

[[Page 14654]]

conditions, NOX contributes over 99.9% of Lake Catherine 
Unit 4's total visibility impacts at all nearby Class I areas on the 
most impacted days. Based on the State's modeling results, the 
visibility impact of this unit from SO2 emissions alone is 
so minimal such that any requirement for additional SO2 
controls on this unit would have virtually no visibility benefit. It is 
clear that the most effective controls to address visibility impairment 
from the source during natural gas firing are those that would reduce 
emissions of NOX. Therefore, in our proposed rulemaking, we 
agreed that it was appropriate for the State to not establish an 
SO2 BART emission limit (i.e. no additional controls) for 
the natural gas firing scenario. This is consistent with the BART Rule, 
which states the following:
    ``Consistent with the CAA and the implementing regulations, States 
can adopt a more streamlined approach to making BART determinations 
where appropriate. Although BART determinations are based on the 
totality of circumstances in a given situation, such as the distance of 
the source from a Class I area, the type and amount of pollutant at 
issue, and the availability and cost of controls, it is clear that in 
some situations, one or more factors will clearly suggest an outcome. 
Thus, for example, a State need not undertake an exhaustive analysis of 
a source's impact on visibility resulting from relatively minor 
emissions of a pollutant where it is clear that controls would be 
costly and any improvements in visibility resulting from reductions in 
emissions of that pollutant would be negligible. In a scenario, for 
example, where a source emits thousands of tons of SO2 but 
less than one hundred tons of NOX, the State could easily 
conclude that requiring expensive controls to reduce NOX 
would not be appropriate.'' \200\
---------------------------------------------------------------------------

    \200\ 70 FR 39116.
---------------------------------------------------------------------------

    Based on our analysis of the data submitted by ADEQ in the Arkansas 
RH SIP, and our agreement that SO2 emissions from burning 
natural gas are very low, we proposed to find that it is appropriate 
for the State to establish no additional control for SO2 
BART. The BART Rule provides that states may determine that for a given 
source no additional control satisfies the BART requirement for a 
particular pollutant.\201\ In such cases, it is not necessary for a 
state to establish an emission limit when no additional control is 
BART. For example, in our final approval of the Kansas RH SIP, we 
approved the State's determination that no additional control (and no 
new BART emission limit) for PM is BART for a number of sources.\202\ 
In our final approval of the Oklahoma RH SIP, we also approved the 
State's determination that no additional control (and no new BART 
emission limit) for PM is BART for a number of sources.\203\ In the 
above cases, Kansas and Oklahoma adopted no new PM emission limit for 
PM BART, and we approved this based on the sources' low visibility 
impact attributable to PM emissions. As such, our proposed approval of 
Arkansas's determination that no additional controls for SO2 
for the natural gas firing scenario satisfies SO2 BART for 
Lake Catherine Unit 4 is consistent with the BART Rule and consistent 
with our action on the RH SIPs of other states.
---------------------------------------------------------------------------

    \201\ 70 FR 39116.
    \202\ 76 FR 52604 and 76 FR 80754.
    \203\ 76 FR 16168 and 76 FR 81728.
---------------------------------------------------------------------------

D. Comments on the Arkansas Pollution Control and Ecology Commission 
Variance for Subject to BART

    Comment: The EPA cannot approve any of the BART determinations 
because each of the BART determinations is premised by Arkansas to 
implement only 5 years after EPA fully approves the entire RH SIP. 
Arkansas's enforceability of BART requirements are codified in Chapter 
15 of Regulation No. 19 and modified in March 2010. Since EPA has not 
yet proposed full approval of the Arkansas RH SIP, EPA's partial 
approval of some pollutant-specific BART requirements in Regulation No. 
19 for some of Arkansas's subject to BART sources will not meet the 
requirements of 40 CFR 51.308(e)(iv). Also, the APCEC variance does not 
account for the possibility that EPA may impose a partial FIP for RH in 
Arkansas, and thus, under the variance, the backstop BART compliance 
deadline will be delayed indefinitely.
    Response: We do not believe that the 2008 submitted Chapter 15 of 
APCEC Regulation No. 19 and its subsequent modification submitted to us 
on August 3, 2010, creates an enforceability timeframe less stringent 
than that required under 40 CFR 51.308(e)(iv). We do not read that the 
partial approval of Arkansas BART determination means that the 
enforceability timeframe is 5 years from the full approval of the AR RH 
SIP. Section 110(k)(3) of the amended Act addresses the situation in 
which an entire submittal, or a separable portion of a submittal, meets 
all applicable requirements of the Act. In the case where a separable 
portion of the submittal meets all the applicable requirements, partial 
approval may be used to approve that part of the submittal and 
disapprove the remainder. Since the portions of the RH SIP submittal we 
are approving are separable from the portions we are disapproving as 
explained above, each approved BART determination for a particular 
pollutant for a given source will have an enforceable date of 5 years 
from the date of EPA's approval. If Arkansas fails to submit a revised 
RH SIP that is approvable for the severable BART determinations we are 
disapproving today, we will promulgate a FIP for the disapproved BART 
determinations; in that case, the compliance deadline will be no later 
than 5 years from the date of the FIP promulgation.
    As explained in our proposed rulemaking and as pointed out in 
another comment, the APCEC variance granted to Arkansas's subject to 
BART sources on March 26, 2010, will require compliance with BART 
requirements ``as expeditiously as practicable but in no event later 
than five (5) years after EPA approval of the Arkansas Regional Haze 
SIP.'' \204\ As explained in our response to that comment, we agree 
that the APCEC variance was never submitted to EPA as a revision to the 
SIP. The operative rule before us is Chapter 15 of Regulation No. 19 
(i.e. the State RH Rule), which requires compliance with BART either 
six years after the effective date of the State's regulation or five 
years after EPA approval of the Arkansas RH SIP, whichever is 
first.\205\ Although we believe this timeframe is consistent with the 
requirements under 40 CFR 51.308(e)(iv), because of the variance 
granted to all Arkansas subject to BART sources, the State of Arkansas 
no longer has the legal authority to enforce compliance within the 
timeframe required by Chapter 15 of APCEC Regulation No. 19, which is 
before us to act upon. Specifically, Arkansas no longer has the 
authority to enforce compliance with BART within six years after the 
effective date of its regulation. 40 CFR 51.230 requires that a state 
must show it has the legal authority to enforce a rule that is 
submitted as part of the SIP. Therefore, we are disapproving the 
portion of the BART compliance provision found in the 2008 submitted 
Chapter 15 of APCEC Regulation No. 19 that requires compliance with 
BART requirements no later than six years after the effective date of 
the State's regulation. For

[[Page 14655]]

purposes of our action on the RH SIP submissions, we are partially 
approving and partially disapproving the portion of the BART compliance 
provision in Chapter 15 of APCEC Regulation No. 19, that requires each 
Arkansas subject to BART source to install and operate BART as 
expeditiously as practicable, but in no event later than five years 
after EPA approval of the Arkansas RH SIP, such that our disapproval is 
of those portions of the regulation that correspond to portions of the 
Arkansas RH SIP we are disapproving. We find that this is consistent 
with the requirements under 40 CFR 51.308(e)(iv). Arkansas's inclusion 
of the compliance provision that would require Arkansas subject to BART 
sources to install and operate BART no later than six years after the 
effective date of the State's regulation (if such date takes place 
before five years from EPA approval of the Arkansas RH SIP) is not a 
required element of the Regional Haze SIPs to be developed and 
submitted by States pursuant to section 169 of the CAA. Therefore, we 
are finalizing our approval of the BART determinations for which we 
proposed approval.
---------------------------------------------------------------------------

    \204\ A copy of the March 26, 2010, APCEC Minute Order granting 
all Arkansas subject to BART sources a variance from the compliance 
deadline imposed by the State's RH Rule can be found in the docket 
associated with this rulemaking.
    \205\ The State's BART compliance requirements are found at Reg. 
19.1504(B).
---------------------------------------------------------------------------

    Comment: Arkansas has not submitted the APCEC variance to EPA as 
part of the Arkansas RH SIP. The version of APCEC Regulation No. 19 
that EPA is proposing to approve requires compliance with BART emission 
limitations no later ``than 6 years after the effective date of 
[Chapter 15 of APCEC Regulation No. 19] or five years after EPA 
approval of the Arkansas Regional Haze State Implementation Plan * * 
*'' (see APCEC Reg. 19.1504(B) in EPA-R06-OAR-2008-0727-0004). 
Compliance with BART under the version of APCEC Reg. 19.1504(B) that 
has been submitted to EPA is required by October 15, 2013, yet ADEQ 
will have no authority to enforce compliance with the deadline that 
will be in effect under the version of APCEC Regulation No. 19 being 
proposed for approval by EPA. EPA's proposed partial approval would be 
of a rule that ADEQ has no authority to enforce. Given that States are 
required to have legal authority to enforce the requirements of the SIP 
(see 40 CFR 51.230(b)), EPA cannot legally approve the BART compliance 
deadline in APCEC Reg. 19.1504(B) until Arkansas properly revises its 
SIP to address the terms of the variance and submits it to EPA for 
approval. EPA seemingly ignores the fact that the variance was not 
adopted by the State as a SIP revision, was not submitted to EPA as a 
SIP revision, and is not being acted on by EPA in this proposed 
rulemaking action. Further, the APCEC variance allows for BART 
compliance deadlines less stringent than the BART compliance deadlines 
of 40 CFR 51.308(e)(iv) of the Federal RH regulations because under the 
variance, compliance would not be required until 5 years from EPA's 
full approval of the Arkansas RH SIP. Therefore, EPA cannot approve any 
of the BART determinations in the Arkansas RH SIP.
    Response: As stated in our proposal, Chapter 15 of APCEC Regulation 
No. 19, was submitted by ADEQ on September 23, 2008, as part of the RH 
SIP submittal. The 2008 submitted Chapter 15 of Regulation No. 19 
requires each subject to BART source to install and operate BART as 
expeditiously as practicable, but in no event later than six years 
after the effective date of Arkansas's Chapter 15 of APCEC Regulation 
No. 19 or five years after approval of the SIP or plan revision by EPA, 
whichever comes first. ADEQ did revise APCEC Regulation No. 19, 
including Chapter 15, and submitted these changes to EPA in 2010 but 
this revised submittal did not include revisions to the provision for 
BART compliance timeframe. We agree with the comment that the APCEC 
variance that requires BART compliance as expeditiously as practicable 
but in no event later than five years after our approval of the 
Arkansas RH SIP has never been submitted to us as a revision to the 
SIP. We do not believe, however, this means we cannot finalize the 
approval of the BART determinations for which we proposed approval. We 
agree that because of the APCEC variance, Arkansas no longer has the 
authority to enforce compliance with BART within six years after the 
effective date of the State's regulation. 40 CFR 51.230 requires that a 
state must show it has the legal authority to enforce a rule that is 
submitted as part of the SIP. Therefore we are disapproving the portion 
of the BART compliance provision found in the 2008 submitted Chapter 15 
of Regulation No. 19 that requires compliance with BART requirements no 
later than six years after the effective date of the State's 
regulation. For purposes of our action on the RH SIP submissions, we 
are partially approving and partially disapproving the portion of the 
BART compliance provision that requires each Arkansas subject to BART 
source to install and operate BART as expeditiously as practicable, but 
in no event later than five years after our approval of the Arkansas RH 
SIP. We find that this is consistent with the requirements under 40 CFR 
51.308(e)(iv). Arkansas's inclusion of the compliance provision that 
would require Arkansas subject to BART sources to install and operate 
BART no later than six years after the effective date of the State's 
regulation (if such date takes place before five years from EPA 
approval of the Arkansas RH SIP) is not a required element of the 
Regional Haze SIPs to be developed and submitted by States pursuant to 
section 169 of the CAA. We also note that with the exception of the PM 
BART determination for the Domtar Ashdown Mill Power Boiler No. 1, our 
partial approval of the State's BART determinations is based on a 
finding that no additional control is required. Therefore the 
compliance date is not relevant for RH purposes since no additional 
controls would be expected for these sources.
    Our actions approving some BART determinations and disapproving 
some BART determinations for Arkansas sources are severable. We can 
approve some of the rules and disapprove the rest as long as the rules 
that are disapproved do not affect those that are approved. This is the 
case in our partial approval and partial disapproval action, in which 
we are disapproving the severable BART determinations for some of the 
units and approving the severable BART determinations for some of the 
units in Arkansas's RH SIP. Since the portions of the RH SIP submittal 
we are approving are severable from the portions we are disapproving as 
explained above, each approved BART determination for a particular 
pollutant for a given source will have an enforceability of 5 years 
from the date of EPA's approval. If EPA cannot approve a revised RH SIP 
for the severable BART determinations EPA is disapproving today before 
the end of the 2 year FIP clock, EPA will promulgate a FIP for the 
severable BART determinations EPA is disapproving today. In that case, 
the compliance deadline will be as expeditious as practicable, but no 
later than 5 years from the date of the FIP promulgation. Therefore, 
EPA disagrees that compliance is required no later 5 years from EPA's 
full approval of the entire Arkansas RH SIP.
    Comment: Under the Federal RH regulations, compliance with BART is 
required ``as expeditiously as practicable,'' and in no event later 
than five years after approval of the SIP (see 40 CFR 51.308(e)(iv), 
and 42 U.S.C. 7491(b)(2)(A)). However, all parties seem to ignore this 
regulatory requirement. Considering this regulatory requirement and the 
significant delay in

[[Page 14656]]

getting an approved RH SIP or FIP in place for Arkansas, EPA must 
consider tighter deadlines for BART compliance.
    Response: It is our role to determine if the State SIP submittal 
meets the requirements of the CAA. Only in the context of a FIP are we 
in a position to make our own determination about the appropriate 
compliance deadline. It is our expectation that the State will correct 
the deficiencies in the SIP and submit a revised plan that we can 
approve before the expiration of the mandatory FIP clock for the 
portions of the SIP we are disapproving in this final rulemaking 
action. However, if this does not occur and we are forced to promulgate 
a FIP, we will consider at such time what the appropriate compliance 
deadline is in light of the final BART determination.

E. Comments on BART and the Forthcoming MACT Requirements

    Comment: Flint Creek Boiler No. 1 and White Bluff Units 1 and 2 
will be subject to EPA's forthcoming EGU MACT requirements, and the 
BART Guidelines provide that MACT requirements should be taken into 
account in determining BART (see 40 CFR part 51, appendix Y, section 
IV.C). The EPA has proposed a total PM limit for existing EGUs of 0.03 
lb/MMBtu, as a surrogate limit for non-mercury metal hazardous air 
pollutants (HAPs) (see 76 FR 24975). EPA should not approve the lax PM 
limit of 0.1 lb/MMBtu for Flint Creek Boiler No. 1 and Entergy White 
Bluff Units 1 and 2 as meeting BART for PM because that emission limit 
is much less stringent than the forthcoming PM MACT requirement. Recent 
stack testing for White Bluff Units 1 and 2 show that the units will 
not be able to meet EPA's proposed mercury MACT limit for existing 
units of 1.2 lb/MMBtu. It is likely that both Flint Creek Boiler No. 1 
and White Bluff Units 1 and 2 will need to install baghouses to meet 
EPA's mercury MACT limit for existing EGUs. It is well known that coal-
fired boilers equipped with baghouses achieve better control of mercury 
than those equipped with ESPs. Activated carbon, a sorbent which 
adsorbs mercury, is typically much more effective when a baghouse is 
used compared to an ESP. According to EPA, the form of mercury most 
easily removed is HgCl2 and the formation of this compound 
depends on how much chlorine is in the coal--the lower the chlorine 
content of the coal, the less HgCl2 is formed. EGUs that 
burn low chlorine coal, such as Flint Creek, often achieve better 
control of mercury via existing SO2 scrubbers and PM 
controls. A fabric filter baghouse provides additional opportunities 
for mercury removal compared to a particle scrubber or a dry ESP.
    Response: We would like to clarify that the section of the BART 
Guidelines the comment refers to was not meant to require States to 
take into account MACT requirements in determining BART, but rather to 
provide States with the option to streamline the BART analysis for 
sources subject to the MACT standards by relying on the MACT standards 
for purposes of BART.\206\ We received the originally submitted 
Arkansas RH SIP on September 23, 2008 and a revision on August 3, 2010, 
while EPA proposed the National Emission Standards for Hazardous Air 
Pollutants from Coal- and Oil-fired Electric Utility Steam Generating 
Units (EGU MACT Rule) on March 16, 2011.\207\ The EPA issued the EGU 
MACT final rule on December 16, 2011.\208\ As such, it would be 
unreasonable for EPA, when taking action on states' RH SIPs, to 
consider EGU MACT standards proposed years after a state submitted its 
RH SIP. This would potentially create an endless review loop for States 
as new MACT standards are issued by EPA. In addition, the limits in the 
MACT standards are established by EPA for reasons that are much 
different than the reasons for the limits established in Regional Haze 
SIPs. Our approval of limits on direct PM emissions in Arkansas for RH 
purposes is based on minimal contribution to visibility impairment at 
Class I areas and is in no way related to the reasons a lower emission 
limit was established under section 112 of the Act. Therefore, EPA 
disagrees that it should disapprove the PM BART limit of 0.1 lb/MMBtu 
adopted by the State for Flint Creek Boiler No. 1 and White Bluff Units 
1 and 2 because it is much less stringent than the PM emission limit in 
the EGU MACT Rule recently promulgated by EPA or because the sources 
may need to install baghouses to meet the mercury emission limit for 
existing EGUs in EPA's EGU MACT Rule. EPA expects that these sources 
will have to comply with these limits under the EGU MACT standard as 
well.
---------------------------------------------------------------------------

    \206\ Appendix Y to Part 51, section IV.C.
    \207\ 76 FR 25091.
    \208\ See http://www.epa.gov/ttn/atw/utility/utilitypg.html for 
a copy of the signed final rule.
---------------------------------------------------------------------------

    Comment: The EPA's reason for proposing to approve a limit of 0.07 
lb/MMBtu and a wet ESP as PM BART for Domtar Power Boiler No. 1 is 
based on an outdated 2004 Boiler MACT PM standard of 0.07 lb/MMBtu and 
because according to EPA, the BART Guidelines provide that unless there 
are new technologies subsequent to the MACT standards which would lead 
to cost-effective increases in the level of control, sources may rely 
on the MACT standards for purposes of BART (76 FR 64207). EPA's 
proposed approval ignores the fact that the 2004 MACT PM standard upon 
which the Domtar Power Boiler No. 1 BART determination is based was 
vacated and remanded and that EPA subsequently promulgated revised 
boiler MACT standards in 2011 which were more stringent. The new 2011 
standards require existing solid fuel-fired boilers like Domtar's Power 
Boiler No. 1 to meet a PM emission limit of 0.039 lb/MMBtu on a 30-day 
rolling average, which is 44% lower than the vacated 2004 0.07 lb/MMBtu 
PM MACT limit (76 FR 15608, 15689 at Table 2). Even though EPA has 
delayed the effective date of the new 2011 Boiler MACT rule until 
completion of reconsideration of the rule and recently reissued a 
reconsideration proposal, there is no legitimate legal basis in the 
applicable regulations for exempting sources from a five-factor BART 
analysis based on their meeting an outdated and formally vacated PM 
MACT standard as reflecting BART when that MACT standard has been 
replaced with a more stringent proposed MACT standard. EPA should 
disapprove the PM BART determination for Power Boiler No. 1 either 
because it is less stringent than required by the MACT standards for PM 
currently being proposed by EPA or because there was no five-factor 
evaluation for BART for PM.
    Response: The EPA acknowledges that on June 8, 2007, the United 
States Court of Appeals for the District of Columbia Circuit vacated 
and remanded the national emission standards for hazardous air 
pollutants for new and existing industrial/commercial/institutional 
boilers and process heaters (i.e. the 2004 Boiler MACT Rule) 
promulgated by EPA on September 13, 2004. However, it should be noted 
that the effective date of this vacatur was July 30, 2007, which was 
after the close of the public notice and comment period for Arkansas's 
proposed RH Rule, which codifies all the BART determinations made by 
the State. On March 21, 2011, the EPA issued a final rule to regulate 
emissions of hazardous air pollutants (HAPs) from industrial, 
commercial, and institutional boilers and process heaters located at 
major sources of HAP emissions (i.e. the ``Major Source Boiler MACT,'' 
or Boiler MACT Rule). As noted in the comment, the Major Source Boiler 
MACT Rule established a PM emission limit of 0.039 lb/MMBtu on a 30-day 
rolling average

[[Page 14657]]

that applies to existing boilers designed to burn solid fuel, such as 
the Domtar Ashdown Mill Power Boiler No. 1. However, EPA promulgated 
the Major Source Boiler MACT Rule years after the end of the State's 
public notice and comment period and years after the date of Arkansas's 
submission to EPA of the RH SIP. As such, it would be unreasonable to 
disapprove the State's PM BART determination for Domtar on the basis 
that it is less stringent than the emission limit in the Major Source 
Boiler MACT Rule issued by EPA on March 21, 2011. Furthermore, on May 
18, 2011, EPA published a final rule delaying the effective date for 
the Major Source Boiler MACT Rule until the proceedings for judicial 
review of the rule is completed or the EPA completes its 
reconsideration of the rule, whichever is earlier.\209\ And on December 
2, 2011, EPA issued a proposed rule for reconsideration of the final 
Major Source Boiler MACT Rule.\210\ The proposed rule for 
reconsideration and the uncertainty surrounding the Major Source Boiler 
MACT Rule is another reason why it is unreasonable for EPA to 
disapprove the State's PM BART determination for Domtar on the basis 
that it is less stringent than the emission limit in the 2011 Major 
Source Boiler MACT Rule.
---------------------------------------------------------------------------

    \209\ 76 FR 28662.
    \210\ 76 FR 80598.
---------------------------------------------------------------------------

    With regard to the comment that EPA should disapprove the State's 
PM BART determination for Domtar Power Boiler No. 1 because there was 
no five-factor evaluation for BART for PM, EPA holds that the State did 
not conduct a BART analysis for PM for Domtar Power Boiler No. 1 
because at the time of the State's analysis, it was relying on the MACT 
standards for purposes of BART. Furthermore, the comment disregards the 
reason why the BART Guidelines provide that States could take a 
streamlined BART approach for sources subject to MACT standards. The 
BART Guidelines provide the following:

``Any source subject to MACT standards must meet a level that is as 
stringent as the best controlled 12 percent of sources in the 
industry * * * We believe that, in many cases, it will be unlikely 
that States will identify emission controls more stringent than the 
MACT standards without identifying control options that would cost 
many thousands of dollars per ton.'' \211\
---------------------------------------------------------------------------

    \211\ Appendix Y to Part 51, section IV.C.

    Accordingly, the reason why the BART Guidelines anticipated that 
states could streamline their analysis by relying on the MACT standards 
for purposes of BART is because EPA believes that such controls are 
among the most stringent available and that emission controls more 
stringent than this are very likely not cost-effective. Notwithstanding 
the court's vacatur of the 2004 Boiler MACT Rule, at the time Arkansas 
performed its analysis and adopted the 0.07 lb/MMBtu emission limit for 
PM BART for the Domtar Ashdown Mill Power Boiler No. 1 based on the 
2004 Boiler MACT PM standard, the emissions controls reflected by that 
PM standard were among the most stringent controls available at that 
time and emission controls more stringent than this were at that time 
likely not cost-effective for purposes of addressing visibility. 
Therefore, EPA disagrees that we should disapprove the PM BART 
determination for the Domtar Ashdown Mill Power Boiler No. 1.

F. Comments on Modeling

    Comment: ADEQ conducted pre-control CALPUFF modeling to show that 
PM10 and PM2.5 emissions from AEP Flint Creek No. 
1 Boiler have minimal visibility impacts. The EPA utilized modeling 
results to exempt White Bluff Units 1 and 2 from a PM BART analysis, 
while ADEQ and Entergy exempted the units from a PM BART analysis based 
on their belief that most of the visibility-causing emissions from 
Units 1 and 2 are due to SO2 and NOX while 
PM10 emissions are well-controlled with existing 
electrostatic precipitators (ESPs). The existing PM emission limit of 
0.1 lbs/MMBtu, which ADEQ adopted as BART for PM, fails to reflect the 
best system of continuous particulate matter reduction at the White 
Bluff units, especially if Entergy is considering the installation of a 
dry scrubber and baghouse at each White Bluff unit to meet BART.
    In addition, the impact threshold used in this analysis is 
problematic because it is likely that ADEQ applied a 0.5 dv threshold, 
although the discussion in the Arkansas RH SIP on the modeling is 
limited or not present. Given the number of sources impacting 
visibility at Class I areas, a 0.5 dv threshold is not appropriate for 
one visibility impairing pollutant. The RHR and BART Guidelines do not 
provide for exempting a source from BART for one visibility impairing 
pollutant. A BART determination must be made for each pollutant and EPA 
cannot exempt Flint Creek Boiler No. 1 and White Bluff Units 1 and 2 
from a BART analysis for PM based on modeling that shows that PM 
visibility impacts do not trip the BART impact threshold.
    Furthermore, the PM modeling used to exempt the source from a PM 
BART determination utilized an emission rate much lower than the 
proposed BART limit. The pre-control modeling for Flint Creek included 
the 24-hr actual maximum emissions rate, which is 70% lower than the 
proposed BART limit of 0.1 lbs/MMBtu. ADEQ modeled White Bluff Unit 1's 
highest 24-hour actual PM10 emission rate of 15.592 grams 
per second and White Bluff Unit 2's highest 24-hour actual 
PM10 emission rate of 16.653 grams per second in determining 
whether the plant's emissions were subject to BART, which is 85% lower 
than the proposed BART limit of 0.1 lbs/MMBtu. The emission limits in 
the April 2007 ENVIRON Report titled ``Cumulative Modeling of Subject 
to Best Available Retrofit Technology (BART) Facilities as a 
Requirement of ADEQ's BART Modeling Protocol'' (Appendix 9.2D of the 
Arkansas RH SIP) are even lower than those used in the pre-control 
modeling.
    Response: In our review of the Arkansas RH SIP, we evaluated the 
determination by ADEQ that no additional PM controls are required for 
the AEP Flint Creek Boiler No. 1 and the Entergy White Bluff Units 1 
and 2. In the case of Flint Creek, ADEQ's determination was based on 
the pre-control modeling performed by ADEQ and a review of AEP SWEPCO's 
statement that the PM visibility modeling did not ``trip the BART 
impact threshold.'' We reviewed the pre-control modeling preformed 
using the 24-hr actual maximum emissions from the baseline period. The 
modeling results in Appendix 9.2B of the AR RH SIP and presented in 
Table 7-6 of Appendix A of the TSD,\212\ indicate that PM contributes 
less than 0.5% of the total visibility impacts from Flint Creek Boiler 
No. 1 at all nearby Class I areas with the exception of Upper Buffalo. 
PM contributions to visibility impacts at Upper Buffalo from Flint 
Creek are less than 2% of the total visibility impairment at this Class 
I area. On the most impacted day at Upper Buffalo, modeling the 24-hr 
actual maximum emissions, PM contributes only 0.07 dv of the total 
3.781 dv modeled visibility impact from the source. Clearly, the most 
effective controls to address visibility impairment from the source are 
those that would reduce emissions of visibility impairing pollutants 
other than direct emissions of PM.
---------------------------------------------------------------------------

    \212\ These documents can be found in the docket for our 
rulemaking.
---------------------------------------------------------------------------

    For Entergy White Bluff units 1 and 2, we reviewed the data 
submitted by ADEQ, including pre-control modeling in Appendix 9.2B of 
the Arkansas RH SIP, to evaluate ADEQ and White Bluff's determination 
that the majority of visibility-causing emissions are due to

[[Page 14658]]

emissions of NOX and SO2, and that no additional 
PM controls are warranted. The modeling results in Appendix 9.2B of the 
Arkansas RH SIP and presented in Table 7-7 of Appendix A of the TSD, 
indicate that PM contributes less than 0.4% of the total visibility 
impacts at all nearby Class I areas. On the most impacted day at Caney 
Creek, modeling the 24-hr actual maximum emissions, PM contributes only 
0.03 dv of the more than 8 dv modeled visibility impact from the White 
Bluff Units 1 and 2. Clearly, the majority of visibility-causing 
emissions are due to emissions of NOX and SO2 and 
the most effective controls to address visibility impairment from the 
units are those that would reduce emissions of NOX and 
SO2 rather than direct emissions of PM. In this action, we 
are finalizing our proposal to disapprove the NOX and 
SO2 BART determinations for these units as ADEQ did not 
properly evaluate and identify controls to address visibility 
impairment from these units.
    In both cases, it is clear that the visibility impact from PM 
emissions alone is so minimal such that the installation of any 
additional PM controls on these units (including any upgrades to the 
existing controls) could only have minimal visibility benefit and 
therefore would not be justified. This is in keeping with the BART 
Rule, which states the following:

    ``Consistent with the CAA and the implementing regulations, 
States can adopt a more streamlined approach to making BART 
determinations where appropriate. Although BART determinations are 
based on the totality of circumstances in a given situation, such as 
the distance of the source from a Class I area, the type and amount 
of pollutant at issue, and the availability and cost of controls, it 
is clear that in some situations, one or more factors will clearly 
suggest an outcome. Thus, for example, a State need not undertake an 
exhaustive analysis of a source's impact on visibility resulting 
from relatively minor emissions of a pollutant where it is clear 
that controls would be costly and any improvements in visibility 
resulting from reductions in emissions of that pollutant would be 
negligible. In a scenario, for example, where a source emits 
thousands of tons of SO2 but less than one hundred tons 
of NOX, the State could easily conclude that requiring 
expensive controls to reduce NOX would not be 
appropriate. In another situation, however, inexpensive 
NOX controls might be available and a State might 
reasonably conclude that NOX controls were justified as a 
means to improve visibility despite the fact that the source emits 
less than one hundred tons of the pollutant.'' \213\
---------------------------------------------------------------------------

    \213\ 70 FR 39116.

    In reviewing the State's PM BART determinations for Flint Creek 
Boiler No. 1 and White Bluff Units 1 and 2, we utilized ADEQ's pre-
control screening modeling using 24-hr maximum actual emissions from 
the baseline period as recommended in the BART guidelines. We did not 
rely on the cumulative modeling results found in Appendix 9.2D of the 
AR RH SIP in our review of ADEQ's PM BART determination for sources at 
these two facilities. Based on our analysis of the data submitted by 
ADEQ in the Arkansas RH SIP, we find that no additional controls are 
required for PM and therefore are finalizing our proposal to find that 
the existing PM emission limits are acceptable to satisfy the PM BART 
requirements of Flint Creek Boiler No. 1 and White Bluff Units 1 and 2.
    Comment: Even though the modeling for Entergy's White Bluff Units 1 
and 2 deviated from the standard modeling protocol in evaluating wet 
and dry scrubbers, these deviations did not impact the BART analysis 
and subsequent BART determination for these units. The use of the 8th 
highest day rather than the maximum visibility impact did not impact 
the BART determination because the units were still determined to be 
subject-to-BART and the BART decision was not based upon modeling. 
Therefore, ADEQ's acceptance of the modeling should be approved by EPA.
    Response: The modeling conducted for Entergy White Bluff Units 1 
and 2 was not conducted appropriately for its purpose and affected the 
BART analysis and subsequent BART determinations for these units. The 
modeling for wet and dry scrubbers at Entergy's White Bluff units 1 and 
2 evaluated both control technologies at an emission limit of 0.15 lb/
MMBtu for SO2. However, wet scrubbers and dry scrubbers are 
capable of achieving a lower emission limit than was modeled by ADEQ, 
and similar facilities use these controls to control SO2 
emissions below the 0.15 lb/MMBtu limit included in the analysis. The 
lowest emission limit achievable must be included in the BART analysis. 
ADEQ evaluated the control effectiveness of the two control options of 
wet and dry scrubbing, stating the wet scrubber can achieve up to 95% 
control efficiency while the dry scrubber can achieve up to 92% control 
efficiency. An emission limit of 0.15 lbs/MMBtu represents a control 
efficiency of only approximately 80% at White Bluff Units 1 and 2. 
Therefore, the visibility modeling is flawed because it did not 
evaluate the level of visibility improvement reasonably achievable due 
to the use of these technologies at the emission rate these 
technologies are capable of achieving.
    Furthermore the original meteorological databases generated by 
CENRAP did not include observations as our guidance recommends. The use 
of meteorological databases that do not include observations may lead, 
to less conservatism in the CALPUFF modeled visibility results compared 
with modeling that uses meteorological databases with observations. To 
account for this, the use of the 1st High modeling values rather than 
8th high modeling values was agreed to by EPA, representatives of the 
Federal Land Managers, and CENRAP stakeholders. The modeling conducted 
for Entergy's White Bluff Units 1 and 2 deviated from this accepted 
modeling protocol by using the 8th highest day rather than the maximum 
impacted day and failed to account in any other way for the loss in 
conservatism that results from using the CENRAP database that does not 
include observations. In summary, an approvable visibility analysis 
would follow the agreed upon modeling protocol for BART and evaluate 
the visibility benefits for the lowest emission limit achievable by 
each technologically feasible control as required by the RHR.
    Comment: We agree with EPA's finding that the visibility impact 
analysis of the SO2 control options for Entergy White Bluff 
Units 1 and 2 was not properly conducted because ADEQ's modeling for 
White Bluff Units 1 and 2 considered both wet and dry scrubbers at the 
same emission rate of 0.15 lb/MMBtu rather than modeling the emission 
rates that these technologies are capable of achieving. In addition, 
the modeling for Entergy's White Bluff Units 1 and 2 deviated from 
ADEQ's modeling protocol by using the 98th percentile value of 
visibility impacts rather than the highest day of impacts.
    Response: As explained elsewhere in our response to comments, we 
find that the visibility impact analysis of the SO2 control 
options for the White Bluff units 1 and 2 was not properly conducted 
because ADEQ's modeling for White Bluff Units 1 and 2 considered both 
wet and dry scrubbers at the same emission rate of 0.15 lb/MMBtu rather 
than modeling the emission rates that these technologies are capable of 
achieving. We find that ADEQ's modeling for Entergy's White Bluff Units 
1 and 2 deviated from ADEQ's modeling protocol by using the 98th 
percentile value of visibility impacts rather than the highest day of 
impacts.
    Comment: ADEQ performed the BART determination modeling in 
accordance with the guidance provided by EPA. ADEQ modeled 
SO2 and NOX together, both pre-control and post-

[[Page 14659]]

control. Modeling results showed the pollutant that impacted visibility 
was SO2 and not NOX. Utilizing this information 
and in compliance with the EPA's BART Guidelines, ADEQ did not make 
BART determination for that source or group of sources (or for certain 
pollutants for those sources) when ADEQ's analysis showed that an 
individual source or group of sources (or certain pollutants from those 
sources) is not reasonably anticipated to cause or contribute to any 
visibility impairment in a class I area.
    Response: We agree that ADEQ pre-control and post-control modeling 
was performed modeling all pollutants (NOX, SO2, 
and PM) together. We note that to properly evaluate the visibility 
benefit from a control, NOX and SO2 emissions 
should be modeled together.
    It is unclear which facility the comment is referring to regarding 
ADEQ not making a BART determination for NOX based on 
modeling that showed SO2 impacted visibility and not 
NOX. ADEQ did make NOX BART determinations for 
all but two subject-to-BART sources. Our concerns with these BART 
determinations are discussed in detail in a separate response to 
comment.
    For AECC Bailey Unit 1 and AECC McClellan Unit 1, ADEQ determined, 
based on pollutant-specific modeling performed subsequent to the 
initial pre-control screening modeling, that NOX 
contributions were less than the 0.5 dv threshold and, as a result, 
incorrectly determined a NOX BART determination was not 
needed for these two units. ADEQ made a NOX BART 
determination for all other sources they determined to be subject-to-
BART. In the case of the two AECC units, as stated in our proposal, our 
evaluation of the screening modeling results for these units reveals 
that on some of the most impacted days, nitrate is a significant 
contributor to the visibility impairment due to these units. Post-
control modeling performed by ADEQ, applying the use of 1% sulfur fuel, 
show that these units would continue to cause or contribute to 
visibility impairment at a number of Class I areas, with NOX 
emissions responsible for over 50% of the impairment on some days under 
this control scenario. The pollutant-specific analysis approach for 
NOX and SO2 used to evaluate controls at these 
AECC units does not take into consideration the chemical interaction 
between these two pollutants and ammonia present in the atmosphere. A 
reduction in sulfate emissions can result in an increase in visibility 
impairment from nitrate due to the increase in ammonia available to 
react with nitrate to form visibility impairing aerosol. The pre-
control modeling results indicate that nitrate is a significant 
contributor to visibility impairment on some days and this contribution 
can increase under conditions of decreased SO2 emissions. 
Therefore, NOX and SO2 emissions should be 
modeled together and emission control technologies should be evaluated 
for both pollutants. In light of the relatively high impacts due to 
nitrate, a combination of NOX and SO2 controls 
may prove to be cost-effective and provide for substantial visibility 
improvement and must therefore be evaluated. We further discuss the 
importance of evaluating all the emissions (NOX, 
SO2, and PM) together from BART sources when assessing the 
benefit in visibility impairment from reductions of NOX and/
or SO2 in another response to comment and also in past EPA 
guidance.\214\
---------------------------------------------------------------------------

    \214\ BART Guidelines; Memo from Joseph Paisie (Geographic 
Strategies Group, OAQPS) to Kay Prince (Branch Chief EPA Region 4) 
on Regional Haze Regulations and Guidelines for Best Available 
Retrofit Technology (BART) Determinations, July 19, 2006; EPA Q and 
A--September 26, 2006.
---------------------------------------------------------------------------

    Comment: The EPA is inconsistent in its approach to the 
contribution threshold to visibility impairment. The EPA initially 
approved ADEQ's selection of a threshold of 0.5 dv in the Arkansas RH 
SIP. However, the EPA later on states that a lower threshold value is 
needed in evaluating pollutant-specific modeling for sources that emit 
more than one visibility impairing pollutant. Arkansas properly modeled 
the visibility impacts of NOX and SO2 emissions 
separately from one another. Arkansas's application of the 0.5 dv 
threshold in considering the impacts of NOX, SO2, 
and PM on a per-pollutant basis is consistent with the BART Guidelines. 
The EPA argues that the 0.5 dv threshold in the BART Guidelines applies 
to all three visibility impairing pollutants combined, and requires the 
state to lower the threshold value in evaluating pollutant-specific 
modeling for sources that emit more than one visibility impairing 
pollutant. This is unsupported as a legal, factual, and policy matter, 
and it is unclear what EPA actually expects states to do on this issue.
    The EPA's proposed rule does not provide any guidance on EPA's 
views as to how Arkansas and other states should modify the 0.5 dv 
threshold to account for separate modeling of PM, on the one hand, and 
NOX and SO2, on the other hand. The EPA cannot 
reasonably purport to require the state to apply a new, untested, and 
previously unarticulated standard in its BART analyses if it does not 
provide guidance on how it should do so. Consistent with the 2006 EPA 
memorandum cited by EPA in its proposal, it is believed that numerous 
BART contribution analyses separating PM from NOX and 
SO2 have been performed without revising the 0.5 dv 
contribution threshold on this basis alone. EPA has not previously 
stated or suggested that any such revision is necessary and there is no 
basis for any suggestion that such a revision is necessary. EPA should 
recognize that states may use the default 0.5 dv contribution threshold 
and allow the application of this threshold regardless of how 
pollutants are modeled. EPA's proposed new approach needlessly 
complicates the analysis, is inappropriate and unsupported, and should 
be withdrawn. ADEQ's selection of a threshold of 0.5 dv is reasonable 
and appropriate, and should be approved by EPA.
    Response: We reviewed ADEQ's methodology to initially identify 
which sources were subject-to-BART. This methodology included modeling 
all pollutants together and applying a contribution threshold of 0.5 
dv. As discussed in our proposed rule, we agree with ADEQ's selection 
of the 0.5 dv threshold as it applies to the initial screening modeling 
performed by ADEQ when all three pollutants, NOX, 
SO2 and PM are considered together.
    We disagree with the characterization of the 0.5 dv threshold as a 
default value. The BART Guidelines state that ``the appropriate 
threshold for determining whether a source contributes to visibility 
impairment' may reasonably differ across states,'' but, ``[a]s a 
general matter, any threshold that you use for determining whether a 
source `contributes' to visibility impairment should not be higher than 
0.5 deciviews.'' 70 FR 39104, 39161. The 0.5 dv threshold is not set as 
a default value but rather a ceiling to what may be determined to be 
appropriate in any situation. Further, in setting a contribution 
threshold, the BART Guidelines say that states should ``consider the 
number of emissions sources affecting the Class I areas at issue and 
the magnitude of the individual sources' impacts.'' 70 FR 39104, 39161. 
The BART Guidelines affirm that states are free to use a lower 
threshold if they conclude that the location of a large number of BART-
eligible sources in proximity of a Class I area justifies this 
approach.
    The pollutant-specific approach is acceptable only for PM BART 
contribution analyses. Furthermore, as

[[Page 14660]]

stated in the 2006 EPA memorandum\215\ referenced in the comment, using 
CALPUFF on a pollutant-specific basis for PM is only appropriate in 
certain situations, such as if a State chooses to adopt the Clean Air 
Interstate Rule (CAlR) program/CSAPR to address emissions of 
SO2 and NOX from EGUs. In such an instance, the 
CAIR/CSAPR may satisfy the requirements for BART for these pollutants 
from these sources. However, the State must determine whether its BART-
eligible EGUs are subject to review under BART for direct emissions of 
PM.
---------------------------------------------------------------------------

    \215\ Memo from Joseph Paisie (Geographic Strategies Group, 
OAQPS) to Kay Prince (Branch Chief EPA Region 4) on Regional Haze 
Regulations and Guidelines for Best Available Retrofit Technology 
(BART) Determinations, July 19, 2006.
---------------------------------------------------------------------------

    Arkansas did not rely on CAIR to address emissions of 
SO2 and NOX. Therefore, pollutant specific 
analysis is not appropriate for a single source analysis. For non-CAIR 
situations, it is necessary to model the source's total emissions 
(NOX and SO2) in any CALPUFF modeling to estimate 
visibility impairment or change in visibility impairment from the 
potential installation of controls or no controls. Separate pollutant-
specific analyses for NOX and SO2 do not take 
into consideration the chemical interaction in the atmosphere. Such 
modeling does not take into account the competition/balance of these 
two pollutants chemical reactions with ammonia present in the 
atmosphere. A reduction in sulfate emissions can result in an increase 
in visibility impairment due to nitrate due to the increase in ammonia 
available to react with nitrate to form visibility impairing aerosol. 
Therefore, NOX and SO2 emissions should be 
modeled together and emission control technologies should be evaluated 
for both pollutants.\216\
---------------------------------------------------------------------------

    \216\ BART Guidelines; Memo from Joseph Paisie (Geographic 
Strategies Group, OAQPS) to Kay Prince (Branch Chief EPA Region 4) 
on Regional Haze Regulations and Guidelines for Best Available 
Retrofit Technology (BART) Determinations, July 19, 2006; EPA Q and 
A--September 26, 2006
---------------------------------------------------------------------------

    ADEQ's approach to modeling a single source on a pollutant specific 
basis could allow for a BART applicable source to model below 0.5 for 
each of the pollutants individually (NOX, SO2, 
and PM), which could lead to a potential cumulative impact of up to 
1.47 dv (3 x 0.49 dv) and yet the source would not be evaluated for 
controls. This process would allow a determination to be made in this 
maximum hypothetical case that a 1.47 dv impact from a subject to BART 
source, which is above the 1.0 dv impact that would result in the 
source causing a significant visibility impairment, would ``screen'' 
out of a full BART analysis using ADEQ's approach. This is not 
appropriate and is inconsistent with our BART Guidelines and guidance. 
In evaluation of pollutant-specific impacts from a source (i.e. 
visibility impacts from PM emissions), consideration of the amount of 
visibility impairment contribution from a source's PM emissions can be 
evaluated against the visibility impairment contribution from the 
source's combined NOX and SO2 emissions.\217\
---------------------------------------------------------------------------

    \217\ Ibid.
---------------------------------------------------------------------------

    EPA also disagrees that we have developed or implemented any new 
guidance in our proposal. EPA's approach is based on the 2005 BART 
guidelines, and additional guidance provided in 2006.
    Comment: Although the use of daily maximum emissions for BART 
modeling purposes meets the modeling protocol, this protocol should be 
revisited due to the fact that using daily maximum emissions is 
completely unrealistic and overly conservative in most cases, as it 
assumes that such an emission rate occurs every day for three years. 
This is especially overly conservative for Unit 1 of the Carl E. Bailey 
Generating Station and Unit 1 of the John L. McClellan Generation 
Station, as these units primarily fire natural gas and have rarely 
fired fuel oil over the past few years. With upcoming EPA environmental 
regulations such as the Utility MACT Rule being promulgated, these 
units are likely to continue the trend of low capacity factors of fuel 
use. Any controls required to be implemented on these units will only 
be used 5% or less of the time, and it is certainly not cost-effective. 
Logic and practicality dictate that the minimal use of fuel oil at 
these two units requires an accommodation in this instance.
    Response: We agree that the modeling protocol and the BART 
Guidelines state that the daily maximum emissions should be used for 
modeling visibility impacts during the baseline period. We note that 
the BART Guidelines do allow for consideration of limited operation of 
a source or fuel type. Given that there are no permit requirements in 
place that would limit the time of operation of the AECC units when 
burning fuel oil, the facilities can legally be operated well above the 
5% capacity factor that AECC assumes it will be operating under in the 
future. It is likely that if the fuel oil burning capacity of these 
units is significantly limited, installation of controls to address the 
emissions during fuel oil burning would prove to be not cost-effective 
on a dollar per ton removed basis. A federally enforceable limit must 
be in place that can be relied upon to limit the emissions of the 
source during fuel oil burning scenarios. We are disapproving the 
SO2 BART analysis for these two units because ADEQ did not 
consider the option of burning fuel oils with sulfur content less than 
1.0%. As articulated in our proposal, the use of fuel oil with a 0.5% 
sulfur content or lower is technically feasible and ADEQ should have 
evaluated its cost effectiveness and visibility impact for the AECC 
Bailey Unit 1 and the AECC McClellan Unit 1. Alternatively, an 
operating air permit restriction to use only natural gas as the fuel 
source for the two units or significantly restricting fuel oil burning 
may be acceptable.
    At this time, it is speculation to assume that the future amended 
MACT rule will lower the capacity factors of fuel use for sources. When 
evaluating a state's BART determination, the EPA looks at existing 
requirements and cannot rely on potential future actions in its 
decision to approve or disapprove a state SIP. ADEQ cannot rely on a 
future MACT Rule to limit the capacity factor of fuel oil use.
    Comment: All post-control CALPUFF modeling completed in Domtar's 
analysis was cumulative-type modeling, taking into account all 
pollutants--NOX, SO2, and PM10 in each 
analysis. The EPA needs to list in detail any concerns about the 
methods used to complete modeling analysis of Domtar's facility.
    Response: We agree with the commenter that post-control modeling 
for the Domtar facility was performed modeling all visibility impairing 
pollutants together (SO2, NOX and PM). As 
discussed in the proposed action, we are finding the chosen model and 
the general modeling methodology used by ADEQ to be acceptable. Because 
Domtar's visibility modeling was performed following the ADEQ modeling 
protocol, we also find that the modeling methodology followed by Domtar 
is acceptable. However, the BART determinations made for the subject-
to-BART units at the Domtar facility were performed without evaluating 
the visibility improvement anticipated due to the use of all 
technically feasible control options. Visibility modeling was performed 
only after a control technology was selected as BART. This approach is 
unacceptable and does not allow for a comparison of the effectiveness 
of available controls in reducing visibility impacts to be considered 
as part of the BART determination. ADEQ's and Domtar's BART 
determinations were flawed

[[Page 14661]]

because the modeling did not evaluate all technically feasible control 
options or evaluate the control technology at the control efficiencies 
they are capable of achieving to inform the BART determination. We 
note, that to properly evaluate the visibility benefit from each 
control, NOX and SO2 emissions must be modeled 
together for each control scenario examined, similar to the modeling 
performed in the post-and pre-control modeling scenarios.
    Comment: The EPA cannot rely on post-control modeling to justify 
the requirement to evaluate post-combustion controls for NOX 
in the agency's disapproval of the BART determinations for Entergy's 
White Bluff facility. While EPA states that post-control modeling shows 
continued post-control modeled visibility impairment due to 
NOX emissions, the models, including CALPUFF, significantly 
overstate nitrate-caused RH, and reliance on those models is not a 
credible approach. Even EPA acknowledges that the CALPUFF model tends 
to magnify the actual visibility effects of an individual source and 
the CALPUFF model is less advanced than some of the recent atmospheric 
chemistry simulations. A more recent version of CALPUFF tends to reduce 
the nitrate over prediction using more advanced chemistry modules 
borrowed from regional models such as CAMx and CMAQ, but this version 
has not been yet approved by EPA. Because there is not a credible 
version of CALPUFF with adequate chemistry to assess the visibility 
impact of Arkansas NOX emissions in an unbiased manner, it 
is helpful to look at actual monitoring data taken at IMPROVE sites and 
to keep in mind that the nitrate chemistry and the IMPROVE monitoring 
data indicate that NO3 particulate formation tends to occur 
on the coldest days, while on warmer days, invisible HNO3 
vapor formation is preferred, which has no visibility impact. The 
Arkansas sources that affect the class I areas subject to this rule are 
south and east of the areas, which are generally not associated with 
the coldest conditions when the worst nitrate haze is observed to 
actually occur.
    Response: We disagree that we relied on post-control modeling to 
justify the requirement to evaluate post-combustion controls. The post-
control model results indicate that even after application of the 
State's selected combustion controls to reduce NOX 
emissions, a significant visibility impact due to NOX 
emissions from White Bluff Units 1 and 2 remains. This demonstrates 
that post-combustion controls that result in larger reductions of 
NOX may prove to be cost-effective and result in significant 
visibility improvement. We note that the modeling of changes in 
visibility impacts is only one of five factors that are evaluated in a 
BART analysis. In performing a BART analysis, the State must take into 
consideration all technologically feasible and available control 
technologies, the costs of compliance, the energy and non-air quality 
environmental impacts of compliance, any pollution control equipment in 
use at the source, the remaining useful life of the source, and the 
degree of improvement in visibility which may reasonably be anticipated 
to result from the use of such technology.\218\ As articulated in more 
detail in our proposal and in our response to previous comments, when 
evaluating NOX controls for White Bluff Units 1 and 2, the 
State considered only combustion controls that would achieve the 
presumptive NOX emission limit even though there are 
technically feasible and available control technologies (including 
post-combustion controls) that are currently being used at similar 
facilities to meet an emission limit much more stringent than the 0.15 
lb/MMBtu presumptive limit for NOX. The BART Guidelines 
provide that in identifying control options for evaluation in a BART 
analysis, states must identify the most stringent option and a 
reasonable set of options for analysis that reflects a comprehensive 
list of available technologies.\219\ In addition, the RHR requires that 
in establishing source specific BART emission limits, a state's BART 
analysis must identify and consider the maximum level of emission 
reduction that has been achieved in other recent retrofits at existing 
sources in the source category.\220\ Therefore, as explained in more 
detail in our response to previous comments, in its NOX BART 
analysis for White Bluff Units 1 and 2, the State must evaluate 
NOX post-combustion controls at the most stringent emission 
limit capable of being achieved by these controls.
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    \218\ See 40 CFR 51.308(e)(1)(ii)(A) and 42 U.S.C. 7491(g)(2).
    \219\ Appendix Y to Part 41, section IV.D.
    \220\ 64 FR 35740.
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    We disagree with the comment's characterization that the CALPUFF 
model approved for regulatory actions is not a credible model to assess 
visibility impacts of NOX emissions from Arkansas sources. 
For the specific purposes of the RHR's BART provisions, we concluded 
that CALPUFF (versions that EPA has approved) is sufficiently reliable 
to inform the decision making process in determining if a full BART 
analysis is required and in estimating the degree of visibility 
improvement that may reasonably be expected from controlling a single 
source in order to inform the BART determination.\221\ When we 
developed the BART Guidelines and determined the acceptability of using 
CALPUFF in estimating visibility impacts from BART sources (BART 
eligible or subject to BART sources), EPA was aware that EPA had not 
approved the regulatory version of CALPUFF for doing full chemistry as 
a Guideline on Air Quality Models (GAQM) preferred model. The final 
BART Guidelines recommend that CALPUFF's 98th percentile modeling 
results be used to estimate the visibility impairment. This is in 
contrast to the approach in our BART Guidelines proposal to use the 
highest daily impact value. We acknowledged that the chemistry modules 
in the CALPUFF model are simplified and likely to provide conservative 
(higher) results for peak impacts. To address the concerns which are 
now being raised by the comment, we made the decision to consider the 
less conservative 98th percentile to account for this potential 
bias.\222\
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    \221\ Regulatory version that had been approved by EPA for 
assessing Long Range Transport of primary pollutants. Final BART 
guidelines published July 6, 2005. (70 FR 39104-39172).
    \222\ ``Most important, the simplified chemistry in the model 
tends to magnify the actual visibility effects of that source. 
Because of these features and the uncertainties associated with the 
model, we believe it is appropriate to use the 98th percentile--a 
more robust approach that does not give undue weight to the extreme 
tail of the distribution.'' 70 FR 39104, 39121.
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    The BART modeling protocol, developed by the CENRAP for use by all 
CENRAP states and reviewed by EPA and the FLM including the use of 
CALPUFF, was adopted by ADEQ. In general, this protocol was followed by 
ADEQ in determining which sources were subject-to-BART and in modeling 
visibility impacts from controls in evaluating BART.\223\ In 
development of the CENRAP BART modeling protocol, we were concerned 
that CENRAP had not included meteorological observation data in 
development of the

[[Page 14662]]

meteorological data sets for the BART CALPUFF modeling. We were 
concerned that this approach, that did not follow our guidelines, would 
lead to some underestimation of impacts. As a result, EPA, FLM 
representatives, states, and stakeholders agreed that they would either 
use the maximum model predicted values (instead of the 98th percentile) 
or develop a modeling protocol to generate the meteorological datasets 
with meteorological observations, which we would then allow the use of 
the 98th percentile. We note that the CALPUFF modeling in ADEQ's SIP 
that was provided by Entergy White Bluff's contractors did not use the 
maximum value but did use the CENRAP meteorological dataset and used 
the 98th percentile, which creates a concern that visibility impairment 
will be underestimated. We noted this concern in our proposal and also 
a concern that Entergy had utilized a higher emission rate than is 
likely achievable by the selected control technology and both of these 
issues would lead to underestimations in the visibility benefit 
anticipated from the use of additional controls.\224\ These issues will 
need to be addressed when a revised BART analysis is completed.
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    \223\ As discussed in detail in a separate response to comment, 
because the CENRAP meteorological databases used in the CALPUFF 
modeling analyses do not include observations, the use of the 
maximum impact rather than the 98th percentile was agreed upon. The 
use of meteorological databases that do not include observations may 
lead, in some applications, to potentially less conservatism in the 
CALPUFF modeled visibility results compared with modeling that uses 
meteorological databases with observations. The use of the 1st High 
modeling values was agreed to by EPA, representatives of the Federal 
Land Managers, and CENRAP stakeholders to account for this.
    \224\ See 76 FR 64205-64207.
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    The comment suggests that CALPUFF version 6.4 has been updated with 
an allegedly more robust chemistry and purportedly performs better 
according to the comment than the current version of the model approved 
for regulatory actions (currently CALPUFF version 5.8). The comment 
claims that CALPUFF version 6.4 was shared with EPA in December 2010. 
We wish to clarify that EPA had a meeting with API representatives and 
others in February 2011. At this meeting, a PowerPoint was shared about 
CALPUFF version 6.4, but the full model code, explanations and 
documentation of the code, model evaluations, etc., have not been 
provided to EPA as of February 2012. We have a detailed procedure for 
evaluation of new models that includes documentation, peer review, 
evaluation, performance analysis, etc. Furthermore, significant changes 
in models (such as a significant upgrade in the chemistry module) are 
often required to go through a formal rulemaking process for adoption. 
As noted by the comment, we previously received comments about the 
CALPUFF version 6.4 model in another action and provided a response 
that a proper review analysis and evaluation have not been 
conducted.\225\ As noted by the comment, the more recently developed 
model version (version 6.4) has not gone through the appropriate review 
to assess if it is founded in appropriate science and performs 
adequately and reliably and is an improvement to the current version 
that is acceptable for regulatory actions. If the revised versions of 
CALPUFF can be shown to be reliable and acceptable to EPA through the 
appropriate process, it would likely be appropriate to the use Highest 
Daily impact (1st High instead of the 8th High) based on the 
presumption that the updated chemistry of the CALPUFF model would 
result in less conservative results than EPA approved CALPUFF versions 
5.8 or 5.711. In past agreements in using the CAMx photochemical model, 
which has a robust chemistry module, Region 6 has required the use of 
the 1st High value when sources are screened out of a full BART 
analysis based on the CAMx results.
---------------------------------------------------------------------------

    \225\ See 76 FR 52431--52434 and the Response to comments 
document (pg. 124-133) for a full agency discussion on why CALPUFF 
version 6.4 (and other non-EPA approved versions) are not acceptable 
at this time for regulatory analyses (EPA Docket ID No. EPA-R06-OAR-
2010-0846).
---------------------------------------------------------------------------

    With regard to the comment's observation that the monitoring data 
indicates visibility impacts due to nitrate formation occur on colder 
days and that these days are not when winds are generally from the 
south or east, EPA notes that monitoring data is only collected every 
three days at each IMPROVE monitor and there is only one monitor in a 
Class I area. Modeling provides for an analysis of visibility 
conditions during every day of the baseline period at a number of 
receptor locations at each Class I area, and is not limited by the 
number of days data is collected. Modeling also allows for receptors to 
be placed throughout the Class I area and not limited to one monitor 
location for estimating visibility impairment throughout the Class I 
areas. Thus, the comment's observation is overly generalized that the 
winds do not generally come from the south and east during the colder 
periods when nitrates are a concern at the Class I areas of concern. 
This overly broad-brushed statement about wind patterns is not 
supported by a more detailed analysis of wind patterns nor transport 
phenomena as wind directions change. We included a more sophisticated 
approach for source-receptor analysis in our BART Guidelines that takes 
into account meteorological transport patterns on every day of the 
year. Since transport of pollutants to the Class I area is not always a 
direct route as wind patterns change, the more sophisticated approach 
discussed in the BART guidelines is to use a full meteorological 
modeling analysis using prognostic meteorological data that has wind 
speed and direction throughout many atmospheric layers from the surface 
to the upper atmosphere. CALPUFF visibility modeling was performed 
using three years (2001-2003) of prognostic meteorological data and 24-
hr actual maximum emissions, following the methods in the BART 
Guidelines. Pre-control and post-control modeling show significant 
visibility impacts due to the Entergy White Bluff's NOX 
emissions, with some of the highest impacted days occurring during the 
fall and winter months. This analysis did not include an evaluation 
based on the most effective emission limit that can be achieved. So it 
is likely that there are underestimates in the visibility improvement 
that could potentially be achieved from installation of BART. The use 
of CALPUFF and prognostic meteorological data that is generated with 
the same meteorological models as weather forecasting, with the many 
layers of wind speed and direction, is a much more appropriate and 
sophisticated approach to analyzing visibility impairment than the 
comment's assessment of potential impacts from Arkansas sources 
indicated. Therefore, we disagree with the statement that the source 
would not be affecting the Class I areas because the winds are not 
generally from the south or east when the coldest conditions occur that 
are associated with the worst nitrate haze.

G. Comments on Legal Issues

1. Comments on Regional Haze
    Comment: The EPA does not have the authority under the CAA to 
partially disapprove portions of Arkansas's RH SIP including BART 
determinations that did not address all the BART factors, BART 
determinations that adopted presumptive limits, Arkansas's LTS, and 
Arkansas's RPGs. The EPA's proposal improperly encroaches on the 
state's authority and discretion in developing a RH SIP. Arkansas has 
properly exercised its statutory authority under the CAA. The EPA must 
defer to Arkansas determinations in their RH SIP since EPA lacks the 
authority to substitute its own judgment or policy preferences for the 
state's determination. The EPA's role in implementing the visibility 
program under the RH SIP is one of support and cooperation in 
implementation.
    Response: The EPA's proposed partial disapproval of Arkansas's RH 
SIP is a proper exercise of EPA's authority under the Clean Air Act. 
Congress crafted the CAA to provide for states to

[[Page 14663]]

take the lead in developing implementation plans, but balanced that 
decision by requiring EPA to review the plans to determine whether a 
SIP meets the requirements of the CAA. The EPA's review of SIPs is not 
limited to support and cooperation in implementation of a state SIP, 
nor is it to simply rubber-stamp state decisions. When reviewing state 
SIPs, EPA must consider not only whether the state considered the 
appropriate factors in making decisions, but acted reasonably in doing 
so. In undertaking such a review, EPA does not usurp the state's 
authority but ensures that such authority is reasonably exercised.
    In taking action on the Arkansas RH SIP submittals, EPA is 
disapproving a portion but approving as much of the Arkansas RH SIP as 
possible. Our action today is consistent with the statute. In 
finalizing our proposed determinations, we are approving the following: 
Arkansas's identification of affected Class I areas; the establishment 
of baseline and natural visibility conditions; the determination of 
URP; Arkansas's RPG consultation; the RH monitoring strategy and other 
SIP requirements under Sec.  51.308(d)(4); Arkansas's commitment to 
submit periodic RH SIP revisions and periodic progress reports 
describing progress towards the RPGs; Arkansas's commitment to make a 
determination of the adequacy of the existing SIP at the time a 
progress report is submitted; and Arkansas's consultation with FLMs. We 
are also largely approving those portions of the SIP addressing 
Arkansas's identification of those sources that are BART-eligible 
sources and those subject to BART sources; some of the State's BART 
determinations for five units; Arkansas's RH Rule; and the LTS.
    We are, however, disapproving some of the State's BART 
determinations for nine units. As explained in the proposal and the 
previous response to comments, some of the State's BART determinations 
for the nine units are not approvable because Arkansas did not follow 
the requirements of section 40 CFR 51.308(e). 76 FR at 64186, at 64187. 
As a result of EPA's disapproval of the BART determinations, we are 
also partially disapproving that portion of the LTS affected by this 
disapproval. Similarly, EPA's disapproval of Arkansas's RPGs is based 
on the state's failure to follow the requirements of 40 CFR 
51.308(d)(i)(A). See also CAA Sec.  169A(g). In concluding that 
Arkansas did not adhere to the requirements of the RHR, EPA is not 
substituting its policy judgment for that of Arkansas but rather 
exercising its authority to ensure that the state's decisions are 
reasonable ones that meet statutory and regulatory requirements.
    Comment: The CAA gives primacy to the states in devising the LTS 
for making reasonable progress toward the national visibility goal and 
in making BART determinations and limited authority to EPA. In 
accordance with section 169A(a)(4), EPA promulgates regulations to 
assure progress towards the national goal of preventing future and 
remedying existing visibility impairment in Federal class I areas while 
the states are required to submit SIP which meets these measures. In 
1999 and 2005, EPA promulgated and subsequently amended the RHR which 
gives guidance to the states on how to develop a visibility program 
that meets the national visibility goal for their state. Section 
169(A)(b)(2) requires States to direct sources subject to BART to 
comply with a BART determination. In accordance with section 169B, 
states, acting together through visibility transport commissions, are 
primarily responsible for formulating a coordinated response to 
interstate transport of visibility. With respect to the RHR and the 
BART Guidelines, the CAA only requires that states take measures 
necessary to make reasonable progress toward the national goal by 
engaging in the process of weighing statutory factors. Regarding EPA's 
role, section 169A(g)(2) (as defined in Train v. Natural Res. Def. 
Council, 421 U.S. 60, 79 (1975)) provides that EPA may disapprove a SIP 
only where a state's SIP fails to meet the minimum CAA requirements.
    Response: We agree that the states are assigned statutory and 
regulatory authority to draft and implement the visibility program as 
well as to make BART determinations for sources within their state. 
Although the states generally have the freedom to determine the weight 
and significance of the statutory factors in making BART determinations 
\226\, they have an overriding obligation to come to a conclusion that 
is based on reasoned analysis. Similarly, states are given flexibility 
in determining reasonable progress, but in making that determination, 
they are required by the CAA to consider certain factors. Whether one 
characterizes EPA's role as limited or not limited in reviewing RH 
SIPs, EPA must determine if the state's SIP meets the applicable 
statutory and regulatory requirements. The state's BART determinations 
for some sources, its LTS, and RPGs were flawed for reasons discussed 
elsewhere in this notice and the proposed rulemaking. While states have 
the authority to exercise different choices in determining BART or 
setting RPGs, such decisions must be reasonable and consistent with 
statutory and regulatory requirements. Arkansas's errors were 
significant enough that we cannot conclude that the state's decision 
met this standard. Our disapproval of portions of the RH SIP has an 
appropriate basis in our CAA authority.
---------------------------------------------------------------------------

    \226\ States must follow the BART Guidelines in making BART 
determinations for EGUs at power plants with a total generating 
capacity greater than 750 MW. 40 CFR 51.308(e)(1)(ii)(B). In 
establishing presumptive limits for these sources, EPA undertook a 
partial weighing of the statutory factors that apply to BART 
determinations.
---------------------------------------------------------------------------

    Comment: U.S. courts agree that EPA's role in reviewing visibility 
programs and determining BART is limited. According to American Corn 
Growers Ass'n v. EPA, 291 F.3d 1 (DC Circuit 2002), states play the 
lead role in designing and implementing RH programs. American Corn 
Growers outlined the legislative history, including the Conference 
Report on the 1977 amendments, when the Court invalidated past 
regulatory provisions regarding BART for constraining state authority. 
The Court stated that the Conference report confirmed that Congress 
intended states to decide which sources impair visibility and what BART 
controls apply to those sources.
    Response: We agree that the CAA places the requirements for 
developing RH plans and determining BART for BART-eligible sources on 
states. As discussed above, EPA's role is to review the RH SIP 
submittal including the BART determinations and determine if the state 
met the applicable statutory and regulatory requirements. While the 
court in American Corn Growers found that EPA had impermissibly 
constrained state authority, it did so because it found that EPA forced 
states to require BART controls without first assessing a source's 
particular contribution to visibility impairment. This is not the case 
with our action. We are not forcing Arkansas to adopt a particular 
measure or to weigh the statutory factors in a particular way. Rather, 
we are disapproving portions of Arkansas's RH SIP that address BART, 
LTS, and RPGs because the state omitted critical analyses and made 
flawed assumptions that compromise any decisions.
    Comment: The Supreme Court has ruled that states have primary 
authority in issues relating to the CAA. In Train v. Natural Res. Def. 
Council, 421 U.S. 60 (1975), the court ruled that EPA had no authority 
to question the wisdom of a state's choices of emissions limitations if 
they are part of a plan which satisfies the standards of the CAA. The 
EPA may

[[Page 14664]]

devise and promulgate a specific plan of its own only if a state fails 
to submit an implementation plan which satisfies those standards.
    Response: Our action does not contradict the Supreme Court's 
decision in Train. States have significant responsibilities in 
implementation of the CAA and meeting the requirements of the RHR. We 
recognize that states have the primary responsibility of drafting an 
implementation plan to address the requirements of the CAA Visibility 
Program. We also recognize that we have the responsibility of ensuring 
that the state plans, including RH SIPs, conform to the CAA 
requirements. We cannot approve a RH SIP that fails to address BART, 
LTS, and RPGs with a reasoned consideration of the statutory and 
regulatory requirements of the CAA and the RHR.
    Comment: Because visibility impairment is primarily aesthetic and 
does not rise to the same level of public policy concern as dangers to 
the public health, Congress made the national visibility goal 
discretionary. Accordingly, unlike other provisions of the CAA, the 
national visibility goal is not considered to be a non-discretionary 
duty of the Administrator under section 169A(f). Likewise, the court in 
American Corn Growers has recognized that the natural visibility goal 
is not a mandate but a goal. In addition, the CAA does not mandate a 
particular timeframe to meet the national goal of natural visibility, 
only that states make reasonable progress. The amount of progress that 
is reasonable is not defined according to objective criteria but 
instead involves balancing of public interest.
    Response: We do not agree that the CAA or RHR prescribes a 
different degree of authority to states based on the program having the 
goal of improving visibility as opposed to preventing adverse human 
health effects. Among other things, the CAA requires states to submit 
plans that satisfy NAAQS standards set to protect both public health 
and welfare. Nothing in the terms of the CAA or its implementation 
history directs that SIP submittals addressing visibility are subject 
to a different standard of evaluation than SIP submittals that directly 
address public health issues associated with air pollutants. The 
distinction is not relevant to state authority to develop RH SIPs and 
does not diminish our responsibility and authority to require that they 
conform to the RHR and the Act.
    More generally, we agree that the CAA does not mandate a particular 
timeframe to meet the national visibility goal. The comment is not 
relevant, however, as our action to partially disapprove Arkansas's RH 
SIP is not based on a finding by EPA that Arkansas's RH SIP fails to 
achieve the national goal. Similarly, EPA is not disapproving 
Arkansas's RH SIP because we disagree per se with the State's 
conclusions as to what constitutes reasonable progress for this time 
period. Our disapproval of the Arkansas RH SIP is based on the fact 
that critical analyses were omitted and that these omissions compromise 
Arkansas's determinations as to the measures necessary to make 
reasonable progress.
    Comment: Although EPA can set national goals and guidelines for the 
RH program, individual states have the authority to select BART for 
specific sources of emissions and design the specific plans that are 
appropriate for respective populations. The RHR does not require a 
definitive dv or percent improvement in visibility. The only thing the 
RHR requires of each state is to demonstrate an improvement in 
visibility. The Arkansas RH SIP meets EPA's national goals and 
guidelines. The Arkansas RH SIP establishes a firm foundation to meet 
the required RPGs and meets and in some cases even exceeds the 
requirements of the RHR.
    Response: We do not agree that the only thing that the RHR requires 
is for each state to demonstrate an improvement in visibility. The RHR 
outlines a process by which states are to evaluate and develop RH SIPs, 
including the process for making BART determinations. The EPA is 
disapproving portions of Arkansas's RH SIP that address BART, LTS, and 
RPGs because the state omitted critical analyses in accordance with the 
requirements of the CAA and the RHR.
    Comment: The preamble to the RHR recognized that States are the 
primary decision makers in determining how to make BART determinations 
and determining which sources are subject to BART. In analyzing the 
applicability of certain executive orders to the proposed RHR, EPA 
states that states will ultimately determine the sources subject to 
BART and the appropriate level of control for such sources, and that 
states accordingly exercise substantial intervening discretion in 
implementing the final rule (70 FR 39155).
    Response: We agree that states are assigned statutory authority to 
determine BART and that EPA has made statements confirming the state's 
authority in this regard. States have the flexibility to determine the 
weight and significance of the statutory factors. However, states must 
make a reasoned determination consistent with the requirements of the 
RHR. As detailed in our proposal and the supporting TSD, Arkansas's 
BART determination for nine units, Arkansas's LTS, and RPGs did not 
provide reasoned determinations conforming to the requirements of the 
RHR.
    Comment: The EPA partially disapproved Arkansas's RH SIP because 
the EPA disagreed with the State's conclusions. The EPA failed to defer 
to the State's lawful exercise of its discretion pursuant to the CAA's 
provisions for visibility protection.
    Response: Our partial disapproval of Arkansas's RH SIP is not based 
on the resulting Arkansas conclusions. Rather our decision to 
disapprove Arkansas's BART determinations for nine units, LTS, and RPGs 
is because the state omitted critical analyses and made flawed 
assumptions that compromise the resulting determinations. The State 
could submit and EPA would approve RH SIP revisions that reached 
identical determinations as the current SIP submittal if Arkansas's 
analysis in reaching those determinations meets the RHR and the Act.
    Comment: The EPA has overstepped its authority in proposing to 
reject the state's BART determinations on the basis of EPA's view that 
the state's consideration of certain statutory factors was not 
``adequate.'' The state, as the determining authority, has the power to 
decide how each of the BART factors should be taken into account and 
weighed. As long as a state considers a given factor, it has met its 
obligations in regards to that factor. Once the state has made its 
decision, EPA has no authority to ``second-guess'' the conclusions that 
the state has reached.
    Response: As explained earlier, the states have the responsibility 
to draft the RH SIP and the EPA has the responsibility of ensuring 
State plans, including RH SIPs, conform to the CAA. As the drafter of 
the RH SIP, the state generally has the authority to decide how each of 
the BART factors are taken into account and weighed. EPA is not 
disapproving Arkansas's BART determinations because it disagrees with 
how Arkansas weighed the relevant factors, such as the cost of controls 
or the degree of visibility improvement resulting from the use of 
controls. The EPA is disapproving certain Arkansas's BART 
determinations because they did not consider these factors in their 
BART determinations in accordance with the RHR and the Act.
    Comment: All of the BART determinations made by Arkansas RH SIP 
should be disapproved because

[[Page 14665]]

Arkansas did not do its own BART analysis in making its BART 
determinations. Instead, Arkansas RH SIP adopted the companies' BART 
analysis as part of the RH SIP and promulgated them into State 
regulation. Given that Arkansas has not made any of its own BART 
determinations, there are no BART determinations for EPA to act on.
    Response: Arkansas submitted a RH SIP which provided BART 
determinations for sources that are subject to BART. Arkansas requested 
that sources subject to BART submit material including a BART analysis. 
Arkansas then reviewed the analysis and data provided by the sources 
and adopted its BART determinations. The EPA reviews RH SIP submittals 
from states that rely upon source-generated data and information to 
evaluate whether the State's decisions meet the Act and EPA rules. In 
Arkansas's case, after their review of the sources' provided 
information, they reached the same BART determinations as was provided 
by the source.
    Comment: Arkansas improperly planned to make its BART 
determinations during the permitting process, not in the SIP submittal. 
In 2009, ADEQ proposed a Title V permit amendment for Entergy's White 
Bluff power plant to, among other things, incorporate BART emission 
limits and requirements, in which ADEQ proposed different pollution 
controls as BART than what was in the company's BART analysis in 
Appendix 9.3 of the Arkansas RH SIP submitted to EPA.
    Response: We disagree that Arkansas planned to make its BART 
determinations during the permitting process, be it through the New 
Source Review preconstruction permitting SIP process or the Title V 
operating permit program. The State adopted its BART determinations 
through rulemaking and they are found in Chapter 15 of APCEC Regulation 
No. 19, as contained in the RH SIP submissions. Each of the BART 
determinations approved by EPA today becomes effective under Federal 
law. It also becomes an applicable requirement that must be included in 
a Title V permit. Any source subject to the BART determinations 
approved today must at a minimum meet these requirements, as expressed 
in 40 CFR 51.308(e). If Arkansas issues a Title V permit that has less 
stringent requirements than the EPA-approved BART determination, then 
the source is subject to Federal enforcement action. It is incumbent 
upon the source to ensure that its Title V permit application meets all 
the applicable Federal requirements. It also is incumbent upon the 
source to ensure that it meets the most stringent applicable Federal 
requirement. If the State wishes to impose BART emission limitations in 
a Title V permit that are different from what EPA is approving today as 
BART, then Arkansas must adopt and submit a revised RH SIP and submit 
it to EPA for approval as a SIP revision.
    Comment: The EPA should not act on any of the company's BART 
analyses, unless it conducts its own analysis of a company's submittal 
in the context of a FIP.
    Response: Under the CAA, we must, within 24 months following a 
final disapproval, either approve a SIP or promulgate a FIP.\227\ As 
stated elsewhere in this final rulemaking, we will consider, and would 
prefer, approving a SIP if the State submits a revised plan that we can 
approve before the expiration of the mandatory FIP clock for the 
portions of the SIP we are disapproving in this rulemaking action. In 
light of this, we are choosing at this time not to perform any BART 
analyses and not to develop and propose a FIP for the BART 
determinations we are disapproving.
---------------------------------------------------------------------------

    \227\ CAA section 110(c)(1).
---------------------------------------------------------------------------

    Comment: The EPA has no reason to disapprove a State BART 
determination that meets the presumptive BART level. The DC Circuit 
Court of Appeals held in American Corn Growers Association v. EPA, that 
there is nothing in the CAA that would require a State to adopt 
provisions more stringent than the Federal requirement.
    Response: In disapproving BART determinations for certain subject-
to-BART sources that adopted the presumptive limits, EPA is not 
requiring Arkansas to establish BART limits that are more stringent 
than Federal requirements. Under the RHR, presumptive limits were 
established to provide a path for States to follow when analyzing BART 
for particular EGUs. The RHR has presumptive limits that act as a 
starting point for the establishment of BART emission limits unless the 
state's analysis indicates that an emission limit more or less 
stringent than the presumptive limit is required. The EPA's BART Rule 
and the BART Guidelines make clear that in developing the presumptive 
emission limits, EPA made many design and technological assumptions, 
and that the presumptive limits may not be BART in every case. As such, 
the presumption in the BART Rule is that the controls reflected by the 
presumptive limits are cost-effective, not that the presumptive limits 
will be BART in every case.
    Thus, EPA's proposed rulemaking on the Arkansas RH SIP did not 
propose to require Arkansas's subject to BART sources to achieve an 
emission rate more stringent than the presumptive emission limits. 
Rather, EPA's proposed rulemaking proposed to disapprove the BART 
emission limits for subject to BART sources where the State adopted 
presumptive emission limits without conducting a proper BART five-
factor analysis. Only after the State conducts a proper evaluation of 
the five statutory factors, as required by 40 CFR 51.308(e)(1)(ii)(A) 
and section 169A(g) of the CAA, or EPA conducts one in the context of a 
FIP, will it be demonstrated whether any of Arkansas's subject to BART 
sources must achieve an emission rate more (or less) stringent than the 
presumptive limits.
    Comment: Because the State of Arkansas adopted EPA's presumptive 
emission limits by default, the State of Arkansas did not fulfill its 
statutory duty under 169A of the CAA and under Arkansas law to 
determine BART. In addition, the State of Arkansas failed to determine, 
using the five factors required under section 169A of the CAA whether 
the actual costs of the proposed control technology justified the 
State's determination of BART for those facilities.
    Response: As explained above, presumptive limits are the starting 
point in a BART determination unless the state determines that the 
general assumptions underlying EPA's analysis in the RHR are not 
applicable to a particular case. Section 169A outlines the analysis 
that is required in order to make a BART determination. We are finding 
that the State's BART determinations for certain subject-to-BART 
sources do not comply with the CAA requirements by adopting the 
presumptive emissions limit without conducting a proper BART five 
factor analysis. Only after the State conducts a proper evaluation of 
the five statutory factors, as required by 40 CFR 51.308(e)(1)(ii)(A) 
and section 169A(g) of the CAA, or EPA conducts one in the context of a 
FIP, will it be demonstrated whether any of Arkansas's subject to BART 
sources must achieve an emission rate more (or less) stringent than the 
presumptive limits.
    Comment: The portion of the Arkansas RH SIP that EPA has proposed 
to approve is not separable from the overall Arkansas RH SIP. The EPA 
should fully disapprove the Arkansas RH SIP because it fails to meet 
the requirements for RH SIPs.
    Response: The Arkansas BART determinations for some of the units, 
LTS, and RPGs are separable portions of

[[Page 14666]]

the RH SIP submittal. The EPA can approve some of the SIP submittal and 
disapprove the remainder as long as the portions that are disapproved 
do not affect those that are approved. This is the case in our action 
partially disapproving Arkansas's RH SIP for its BART determinations 
for some of the units, LTS, and RPGs and approving the remainder of the 
RH SIP.
2. Comments on Interstate Transport and Visibility
    Comment: Arkansas's April 2008 Interstate Transport SIP was in 
accordance with the 2006 Guidance, and virtually identical to those 
submitted by Arizona, Iowa, Kansas, Minnesota, Nebraska, Nevada, South 
Dakota, Utah, and Wyoming. The EPA approved those states' Interstate 
Transport SIPs in a timely fashion because they were consistent with 
EPA's 2006 Guidance, yet ignored Arkansas's Interstate Transport SIP 
until after EPA's statutory deadline to act; when it evaluated the SIP, 
it was not by the criteria established in the 2006 Guidance. In an 
August 2011 rulemaking to promulgate a Federal implementation plan 
(FIP) for visibility improvement in New Mexico, EPA for the first time 
claimed its 2006 Guidance interpreting the Good Neighbor Provision of 
the CAA- on which Arkansas had based its 2008 Interstate Transport SIP- 
had been published ``in error'' (76 FR 52418). In the same rulemaking, 
EPA put forth a new framework for interpreting the requirements 
pursuant to the visibility component of the Good Neighbor Provision. 
Inconsistent with the 2006 Guidance, EPA now holds that it is possible 
to determine whether a state is violating the Good Neighbor Provision, 
based on what the state ``should'' have in its Regional Haze SIP. EPA's 
new criteria for evaluating Interstate Transport SIP submissions is 
based on the air quality modeling performed by regional planning 
organizations, and on whether there are differences between emissions 
reductions in a state's RH SIP and emissions reductions assumptions 
derived from the air modeling performed by regional planning 
organizations. Although EPA has not issued a new guidance document to 
reflect what states ``should'' have in their SIPs ``at this point in 
time,'' EPA has approved the visibility component of several Interstate 
Transport SIPs using criteria other than the 2006 Guidance. The EPA has 
not explained this regulatory inconsistency between its treatment of 
Arkansas's Interstate Transport SIP versus Arizona, Iowa, Kansas, 
Minnesota, Nebraska, Nevada, South Dakota, Utah, and Wyoming's 
Interstate Transport SIPs. The EPA cannot hold different states to 
different requirements pursuant to the visibility component of the 
CAA's Good Neighbor Provision.
    Response: Section 110(a)(2)(D)(i)(II) does not explicitly define 
what is required in SIPs to prevent the prohibited impact on visibility 
in other states nor does it explicitly define how to determine if an 
action by a state is interfering with another state's specific 
visibility measure. A RH SIP that provides for emissions reductions 
consistent with the assumptions used in the modeling of other CENRAP 
states is an appropriate way to meet a state's obligations to the other 
regional planning states with regards to non-interference with another 
state's visibility measures is consistent with the CAA.
    On March 28, 2008, Arkansas submitted revisions to its section 
110(a)(2)(D)(i) Interstate Transport SIP. In its March 28, 2008 SIP 
submission, Arkansas stated it is meeting the requirements for 
protection of visibility in section 110(a)(2)(D)(i)(II) by the adoption 
in 2007 of Chapter 15 of APCEC Regulation No. 19, which established 
Arkansas's RH program requirements. Arkansas also stated in the March 
28, 2008, SIP submission, that it was not possible at that time to 
assess whether there is interference with measures in the applicable 
SIP for another state until the Arkansas RH SIP is submitted and 
approved by EPA. Arkansas also submitted Chapter 15, Regulation 19 in 
its September 9, 2008 RH SIP submittal. The Arkansas RH regulation 
established a compliance timeframe of October 15, 2013, six years after 
the adoption of the state regulation or within five years of the date 
of the approval of the RH SIP by EPA, whichever date comes first. 
Chapter 15, Regulation 19 outlined the BART determinations for sources 
within Arkansas including some sources that do not require a mandatory 
BART determination under the RHR. The emission reductions resulting 
from the State BART determinations codified in Chapter 15, Regulation 
19 are identical to the emissions reductions promised by Arkansas to 
the other CENRAP member states and included in the CENRAP 2018 
emissions inventory modeling to represent Arkansas's share of emission 
reductions for the region. The CENRAP member states are basing their 
RPGs and RH programs from this anticipated CENRAP 2018 emissions 
inventory modeling. On September 23, 2008, Arkansas submitted its RH 
SIP including Chapter 15, Regulation 19 to EPA for approval.
    The EPA could have approved Arkansas's 110(a)(2)(D)(i) Interstate 
Transport SIP in 2008 when Arkansas originally submitted the SIP. 
Chapter 15, Regulation 19 originally established a compliance timeframe 
of October 15, 2013, six years after the adoption of the state 
regulation or within five years of the date of the approval of the RH 
SIP by EPA, whichever date comes first. This provided the necessary 
emission limits and enforceable mechanisms to ensure Arkansas's 
apportionment of emissions reductions used in the CENRAP modeling. 
However, on March 17, 2010, Arkansas granted a variance from the 
October 15, 2013 deadline imposed by Regulation 19.1504(B) for sources 
subject to BART listed at Regulation 19.1504(A). Instead, sources 
subject-to-BART are required to comply with BART only within five years 
after EPA approves Arkansas's RH SIP. This variance was never submitted 
to EPA as a SIP revision. As explained in an earlier response to 
comments, we are disapproving the portion of the BART compliance 
provision found in the 2008 submitted Chapter 15 of Regulation No. 19 
that requires compliance with BART requirements no later than six years 
after the effective date of the State's regulation since Arkansas no 
longer has the legal authority to enforce this provision. We are 
partially approving and partially disapproving the portion of the BART 
compliance provision that requires each Arkansas subject-to-BART source 
to install and operate BART as expeditiously as practicable, but in no 
event later than five years after EPA approval of the Arkansas RH SIP 
consistent with the requirements under 40 CFR Sec.  51.308(e)(iv). 
Because of our disapproval of the six year compliance timeframe in 
Arkansas's 2008 submitted Chapter 15 of Regulation 19, as well as 
disapproval of certain BART determinations, all of Arkansas's promised 
enforceable emission reductions factored into CENRAP's 2018 emissions 
inventory modeling and relied upon by fellow CENRAP member states in 
developing their RPGs and RH SIPs will not be met. Thus, the 
requirements for section 110(a)(2)(D)(i)(II) will not be met.
    If we had acted upon the Arkansas RH SIP earlier than 2010, it 
would not change EPA's determination that Arkansas's emissions are 
interfering with other states' visibility programs because Arkansas's 
subsequent adoption of the BART variance removing the guaranteed six 
year compliance requirement would have rendered the hypothetically-
approved section

[[Page 14667]]

110(a)(2)(D)(i)(II) SIP provisions unenforceable. To address this, we 
would be required to issue a SIP Call now and Arkansas would be 
required to revise its SIP to correct the inadequacies by a given due 
date or face sanctions for failure to timely submit a complete SIP 
revision. The BART determinations we would have disapproved in our 
earlier hypothetical action would no longer be required to occur by 
October 2013 under the State's law regardless of EPA's disapproval 
action, and therefore Arkansas emissions would continue to interfere 
with other states' visibility programs. The emissions reductions 
resulting from those BART determinations would not be required to 
happen at all since the variance conditions BART compliance upon EPA 
approval of the Arkansas RH SIP.
    The EPA's partial disapproval of Arkansas's SIP addressing section 
110(a)(2)(D)(i)(II) is consistent with EPA's actions on the SIPs of 
Arizona, Iowa, Kansas, Minnesota, Nebraska, Nevada, South Dakota, Utah, 
and Wyoming. Section 110(a)(2)(D)(i)(II) does not explicitly define 
what is required in SIPs to prevent the prohibited impact on visibility 
in other states. However, because the RH program requires measures that 
must be included in SIPs specifically to protect visibility, EPA's 2006 
Guidance recommended that RH SIP submissions meeting the requirements 
of CAA section 110(a)(2)(D)(i)(II) with respect to visibility would be 
sufficient. We approved the SIPs of Arizona, Iowa, Kansas, Minnesota, 
Nebraska, Nevada, South Dakota, Utah and Wyoming in accordance with the 
2006 Guidance in 2007 and 2008. However, our 2006 Guidance reflected 
our recommendations for how states could potentially meet the section 
110(a)(2)(D)(i)(II) requirement at that point in time. As of August 
2006, we stated our belief that it was ``currently'' premature for 
states to make a more substantive SIP submission for this element, 
because of the anticipated imminent RH SIP submissions. We explicitly 
stated that ``at this point in time'' in August of 2006, it was not 
possible to assess whether emissions from sources in the state would 
interfere with measures in the SIPs of other states. As subsequent 
events have demonstrated, we were mistaken as to the assumption that 
all states would submit RH SIPs in December of 2007 and mistaken as to 
the assumption that all such submissions would meet applicable RH 
program requirements and therefore be approved shortly thereafter. 
Thus, the premise of the 2006 Guidance that it would be appropriate to 
await submission and approval of such RH SIPs before evaluating SIPs 
for compliance with section 110(a)(2)(D)(i)(II) was in error. Our 2006 
Guidance was clearly intended to make recommendations that were 
relevant at that point in time, and subsequent events have rendered it 
inappropriate in this specific action.
    Because of the need to act immediately on section 110(a)(2)(D)(i), 
when some states did not make the RH SIP submission in whole or in 
part, or did not make an approvable RH SIP submission, we have 
evaluated whether states could comply with section 110(a)(2)(D)(i)(II) 
by other means. Thus, we have elsewhere determined that states may also 
be able to satisfy the requirements of CAA section 110(a)(2)(D)(i)(II) 
with something less than an approved RH SIP, see e.g. Colorado (76 FR 
22036 (April 20, 2011)), Idaho (76 FR 36329 (June 22, 2011)), and New 
Mexico (76 FR 52388 (August, 22, 2011)). In other words, an approved RH 
SIP is not the only possible means to satisfy the requirements of CAA 
section 110(a)(2)(D)(i)(II) with respect to visibility; however such a 
SIP could be sufficient.
    As stated earlier, Arkansas submitted revisions to its section 
110(a)(2)(D)(i) Interstate Transport SIP that addressed the 
requirements for protection of Visibility in section 
110(a)(2)(D)(i)(II) by enacting the Arkansas Pollution Control and 
Ecology Commission regulation Chapter 15, Regulation 19 that 
established Arkansas's RH program requirements and stating that it was 
not possible at this time to assess whether there is interference with 
measures in the applicable SIP for another state until Arkansas's RH 
SIP is submitted and approved by EPA. Since EPA was no longer waiting 
for the approval of a RH SIP to determine interference with another 
state's visibility program, we looked at BART determinations cited in 
Chapter 15, Regulation 19 and submitted in their Interstate Transport 
SIP. The emission reductions resulting from the BART determinations in 
Chapter 15, Regulation 19 are identical to the emissions reductions 
promised by Arkansas to the other CENRAP member states and included in 
the 2018 CENRAP modeling to represent Arkansas's share of emission 
reductions for the region. The CENRAP member states are basing their 
RPGs and RH programs on this CENRAP modeling.
    As in New Mexico, we have determined that the analysis conducted by 
a RPO such as CENRAP provides an appropriate means to ensure that 
emissions from sources within the state are not interfering with the 
visibility programs of other states, as contemplated in section 
110(a)(2)(D)(i)(II). In developing their visibility projections using 
photochemical grid modeling, CENRAP states assumed a certain level of 
emissions from sources within Arkansas. Although we have not yet 
received all RH SIPs, we understand that the CENRAP states used the 
visibility projection modeling to establish their own respective RPGs. 
Thus, we believe that an implementation plan that provides for 
emissions reductions consistent with the assumptions used in the CENRAP 
modeling will ensure that emissions from Arkansas sources do not 
interfere with the measures designed to protect visibility in other 
states.
    For Arkansas, the EPA is disapproving certain BART determinations. 
This means that some sources within Arkansas do not have an enforceable 
emission reduction requirement to meet the emissions reductions 
promised by Arkansas to CENRAP member states and modeled by CENRAP in 
their anticipated 2018 emissions inventory because, as explained 
earlier, Arkansas's enactment of a variance that conditions the BART 
determinations in Chapter 15, Regulation 19 upon EPA's approval of 
Arkansas RH SIP. Since Arkansas no longer has an enforceable 
requirement for certain Arkansas BART determinations that EPA is 
disapproving, their promised emissions reductions included in CENRAP's 
modeling and the resulting 2018 emissions inventory will not be 
realized even though other CENRAP member states are relying upon them 
in the promulgation of their RPGs and RH SIPs. Thus, our disapproval of 
some of Arkansas's BART determination means that we have to disapprove 
a portion of the section 110(a)(2)(D)(i)(II) SIP submittal.
    Comment: The EPA cannot at this time make a determination of 
whether Arkansas RH SIP interferes with measures in another state's RH 
SIP for purposes of protecting visibility since EPA has not yet 
approved any other RH SIP for a state with a class area that may be 
affected by Arkansas sources.
    Response: We disagree that we cannot make a determination of 
whether the Arkansas RH SIP interferes with measures in another state's 
RH SIP for purposes of protecting visibility without approving other 
states' RH SIPs that have a class I area that may be affected by 
Arkansas sources. The comment is inconsistent with the objectives of 
the statute to protect visibility programs in

[[Page 14668]]

other states if a state never submits an approvable RH SIP. Second, 
this approach is inconsistent with the time requirements of section 
110(a)(1) which specifies that SIP submissions to address section 
110(a)(2)(D)(i), including the visibility prong of that section, must 
be made within three years after the promulgation of a new or revised 
NAAQS. While there have been delays with both RH SIP submissions by 
states and our actions on those RH SIP submissions, those delays do not 
support a reading of the statute that overrides the timing requirements 
of the statute. At this point in time, states are required to have 
submitted RH plans to EPA that establish RPGs for class I areas. This 
requirement applies whether or not states have, in fact, submitted such 
plans. We believe that there are means available now to evaluate 
whether a state's section 110(a)(2)(D)(i)(II) SIP submission meets the 
substantive requirement that it contain provisions to prohibit 
interference with the visibility programs of other states, and 
therefore that further delay, until all RH SIPs are submitted and fully 
approved, is unwarranted and inconsistent with the key objective to 
protect visibility.
    Comment: There is nothing in the record to demonstrate that 
Arkansas RH SIP interferes with any measure included in any other 
state's SIP for the purpose of protecting visibility. Missouri is the 
only state with Federal Class I areas where visibility is impacted by 
the interstate transport of haze-causing emissions originating in 
Arkansas, and per a consent decree, EPA is not required to act on 
Missouri's Regional Haze SIP submission until June 15, 2012 (76 FR 
75544).
    Response: As explained in an earlier response, the EPA does not 
have to wait to make a determination of interference with another 
state's visibility program until EPA approves Arkansas's RH SIP or the 
surrounding states' RH SIPs that have a class I area affected by 
Arkansas emissions because EPA has a duty to act and an ability to make 
a section 110(a)(2)(D)(i)(II) determination through means other than an 
approvable RH SIP. Arkansas is a member state of CENRAP, the regional 
planning committee on regional haze. Each state based its RH Plans and 
RPGs based on CENRAP modeling. The CENRAP modeling was based in part on 
the emissions reductions each state intended to achieve by 2018. In the 
case of Arkansas, some of the emissions reductions included in the 
modeling, and thus relied upon by other states, were from BART controls 
on Arkansas subject to BART sources. Since, as discussed in a previous 
response, compliance of Arkansas's subject to BART sources with BART 
requirements is dependent upon our approval of the RH SIP, and since we 
are proposing to disapprove the portion of the RH SIP which includes 
some of Arkansas's BART determinations, a portion of the emission 
reductions committed to by Arkansas and relied upon by other states 
including Missouri will not be realized. As a consequence, Arkansas's 
emissions will interfere with other states' SIPs to protect visibility. 
Therefore, we are partially approving and partially disapproving the 
portion of the Arkansas Interstate Transport SIP submittal that 
addresses the visibility requirement of section 110(a)(2)(D)(i)(ii) 
that emissions from Arkansas sources not interfere with measures 
required in the SIP of any other state under part C of the CAA to 
protect visibility.
    Comment: To the extent that EPA's disapproval of the Arkansas RH 
SIP is premised on the language in section 110(a)(2)(D)(i)(II), but is 
not based on direct interference with a specific measure in another 
state's RH SIP, as opposed to interference with a RH related goal in or 
underlying another state's SIP as required by statute, EPA's 
interpretation is contrary to the clear and express language of section 
110 of the CAA.
    Response: Section 110(a)(2)(D)(i)(II) does not explicitly define 
what is required in SIPs to prevent the prohibited impact on visibility 
in other states nor does it explicitly define how to determine if an 
action by a state is interfering with another state's specific 
visibility measure. A RH SIP that provides for emissions reductions 
consistent with the assumptions used in the modeling of other CENRAP 
states is appropriate to meet a state's obligations to the other 
regional planning states with regards to non-interference with another 
state's visibility measures and is consistent with the CAA. The ``2006 
Guidance for SIP Submissions to Meet Current Outstanding Obligations 
Under Section 110(a)(2)(D)(i) for the 8-Hour Ozone and PM2.5 NAAQS'' 
defined that a RH SIP submittal can determine whether or not a state 
SIP for 8 hour ozone or PM2.5 contain adequate provisions to 
prohibit emissions that interfere with measure in other states. As 
explained earlier, Arkansas chose to meet their section 
110(a)(2)(D)(i)(II) requirements through their BART determinations. 
These emissions reductions were promised to other CENRAP states and 
included in the CENRAP modeling used by other states to develop their 
RPGs. As discussed previously, by Arkansas having some of its BART 
determinations disapproved today by EPA, Arkansas will no longer meet 
its committed-to emission reductions that the other states are relying 
on in order to meet their RH SIPs and RPGs.
    Comment: The EPA's interpretation of section 110(a)(2)(D)(i)(II) is 
contrary to the CAA's clear direction that each state is to determine 
its own emission limits, schedules of compliance, and other measures 
for sources in that state for purposes of visibility protection under 
169A. The EPA's interpretation would effectively give one state the 
power to control another state's RH SIP decisions including its BART 
determinations.
    Response: As explained earlier, Arkansas elected to have its 
promised emission reductions used in the CENRAP modeling and relied 
upon by other CENRAP member states. These emission reductions Arkansas 
committed to are reflected in the Arkansas RH SIP submittal from BART 
controls on Arkansas subject to BART sources. An approved RH SIP that 
includes emissions limits, schedules of compliance, and other measures 
for sources in that state for purposes of visibility protection under 
169A is not the only possible means to satisfy the requirements of CAA 
section 110(a)(2)(D)(i)(II). States can meet section 
110(a)(2)(D)(i)(II) by adopting emissions limits that were promised as 
part of the regional planning process. A RH SIP submittal including 
BART controls on subject to BART sources can also meet the requirements 
of section 110(a)(2)(D)(i)(II). Arkansas chose to take both of these 
approaches by adoption of their promised CENRAP emissions reductions in 
their BART determinations as submitted in their RH SIP under Arkansas 
Chapter 15, Regulation 19.
    This approach does not give one state the power to control another 
state's RH SIP decisions including its BART determinations. Each 
individual state member of the regional planning committee has the 
autonomy to make their own decisions on how they are going to reduce 
their state's emissions and contribute to the overall group's effort to 
reduce RH in the region. We are abiding by Arkansas's decision to have 
its BART determinations be representative of promised emission 
reductions relied upon by other states. As discussed previously, by us 
disapproving some of Arkansas's BART determinations, the relied-upon 
emissions reductions used in the development of other CENRAP member 
state RPGs and RH SIPs will not occur. Therefore, we are partially 
approving and partially disapproving the portion of the Arkansas 
Interstate Transport SIP

[[Page 14669]]

submittal that addresses the visibility requirement of section 
110(a)(2)(D)(i)(ii) that emissions from Arkansas sources not interfere 
with measures required in the SIP of any other state under part C of 
the CAA to protect visibility.
    Comment: Based upon EPA's 2006 Interstate Transport Guidance, 
conclusions regarding whether emissions from any one state could 
interfere with measures of neighboring states to protect visibility can 
only be reached when a neighboring state's RH SIP has been approved. 
This has not occurred. In addition, the 2006 Interstate Transport 
Guidance provides that a state satisfies the requirements of the 
visibility component of the interstate transport SIPs by submitting an 
Interstate Transport SIP confirming that it is not possible at the time 
of that submission to assess whether a state's emissions would 
interfere with measures required to protect visibility in the 
applicable SIP for another state and submit a RH SIP at a later date 
and approved by EPA. This is what Arkansas did. In keeping with the 
2006 Guidance, EPA should instead approve Arkansas's 2007 Interstate 
Transport SIP and confine its action on visibility impairment to 
proceeding on the state's RH SIP and not act on section 
110(a)(2)(D)(i)(II) until the state's RH SIP is approved.
    Response: Our guidance on submissions in August of 2006 states that 
``at this time point and time,'' it is not possible to assess whether 
emissions from sources in the state would interfere with measures in 
the SIPs of other states until RH SIPs are submitted and approved. At 
the time of the writing of the 2006 Guidance, we mistakenly assumed 
that all states would submit RH SIPs in December of 2007, as required 
by the RHR, and mistakenly assumed that all such submissions would meet 
applicable RH program requirements and therefore be approved shortly 
thereafter. This did not happen. Thus, our premise, as stated in the 
2006 Guidance, that it would be appropriate to await submission and 
approval of such RH SIPs before evaluating SIPs for compliance with 
section 110(a)(2)(D)(i)(II), was in error. This is especially true in 
light of the timing requirements of section 110(a)(1) which specifies 
that SIP submissions to address section 110(a)(2)(D)(i), including the 
visibility prong of that section, must be made within three years after 
the promulgation of a new or revised NAAQS. Our 2006 Guidance was 
clearly intended to make recommendations that were relevant at that 
point in time, and subsequent events have made it unsuitable to delay 
this action regarding Arkansas's emissions interfering with other 
state's visibility measures before all RH SIPs affected by Arkansas 
emissions are approved. We must therefore act upon Arkansas's 
submission in light of the actual facts, and in light of the statutory 
requirements of section 110(a)(2)(D)(i). In order to evaluate whether 
the state's SIP currently in fact contains provisions sufficient to 
prevent the prohibited impacts on the required programs of other 
states, we are obligated to consider the current circumstances and 
investigate the levels of controls at Arkansas sources and whether 
those controls are or are not sufficient to prevent such impacts. Here, 
as explained earlier, Arkansas promised emission reductions from BART 
eligible sources and had those emissions reductions included in the 
CENRAP modeling that other states are relying on in developing their 
RPGs and RH SIPs. Because we are disapproving some of Arkansas's BART 
determinations, as previously discussed, Arkansas will not meet its 
CENRAP emission reduction commitments relied upon by other states. 
Thus, Arkansas's sources will interfere with other state's visibility 
measures.
    Comment: The EPA's proposed rule is incorrect in its conclusion 
that the 1997 promulgation of new or revised NAAQS for PM2.5 
and ozone created an obligation in the part of Arkansas (or any other 
state) to submit a section 110(a)(2)(D)(i)(II) SIP revision with 
respect to visibility protection. Promulgation or revision of any NAAQS 
is entirely unrelated to the Part C visibility SIP requirements. The 
only additional SIP obligations with respect to section 
110(a)(2)(D)(i)(II) and new or revised NAAQS are NAAQS attainment and 
maintenance. No obligation to address Part C visibility components of a 
SIP arises merely as a result of NAAQS promulgation or revision. The 
EPA should conclude that the promulgation of revised ozone and 
PM2.5 NAAQS creates no obligation on the part of any state 
to submit any section 110(a)(2)(D)(i)(II) SIP revision with respect to 
visibility protection.
    Response: We disagree. Reduced visibility is an effect of air 
pollution, and the emissions of PM2.5 and ozone and its 
precursors can contribute to visibility impairment. SIP planning for 
the control of these pollutants on the promulgation of a new NAAQS will 
therefore implicate control measures and issues relating to visibility. 
CAA section 110(a)(1) therefore requires implementation plans submitted 
in the wake of a newly promulgated NAAQS to address whether the state 
has adequate provisions to prevent interference with the efforts of 
other states to protect visibility. The obligation to address Part C 
visibility components expressly follows from the language of section 
110(a) concerning when plans must be submitted and what each 
implementation plan must contain.
    Comment: The EPA mistakenly refers to the ``Interstate Transport 
SIP'' in its proposed disapproval of a portion of the Arkansas 
Interstate Transport SIP that addresses the visibility requirement of 
section 110(a)(2)(D)(i)(II) that emissions from Arkansas sources not 
interfere with other state's visibility protection programs, but it is 
more accurately referred to as an ``Infrastructure SIP.'' In addition, 
the EPA failed to include in its proposed disapproval that it did not 
immediately require the state to make these SIP submittals. When EPA 
was sued for not having these submittals, the EPA issued its finding of 
failure notices to all states. If these SIPs had been required and 
submitted upon promulgation of the 1997 revision to the NAAQS for 8-
hour ozone, it is unlikely that the RH program would have been 
considered an element of a typical ``Infrastructure SIP.''
    Response: Interstate Transport SIPs and Infrastructure SIPs address 
SIP requirements under section 110 under the CAA which requires states 
to adopt and submit to EPA a SIP that includes elements 110(a)(2)(A) 
through (M) within three years after the promulgation or revision of a 
NAAQS. The EPA has requested states to submit their SIP separately 
addressing Section 110 Infrastructure requirements and Section 110 
Interstate Transport requirements. However, this does not have a legal 
effect on the contents of the SIP submittal. Section 110(a)(2)(D)(i) 
elements are reviewed at the same legal standard whether the section 
110(a)(2)(D)(i) elements are submitted as part of an Interstate 
Transport SIP or an Infrastructure SIP submittal.
    At issue is Arkansas's requirement to submit a SIP that addresses 
the 1997 revision to the NAAQS for 8-hour ozone and PM2.5. 
On July 18, 1997, the EPA promulgated new NAAQS for eight-hour ozone 
and for PM2.5. Section 110(a)(1) of the CAA requires states 
to submit new SIPs to provide for the implementation, maintenance, and 
enforcement of new or revised NAAQS. SIPs for a new or revised NAAQS 
must contain adequate provisions to address interstate transport of air 
pollution, pursuant to section 110(a)(2)(D)(i). The Clean Air Act 
requires states to submit SIPs within three years of promulgation of a 
new or revised NAAQS. This duty to submit a SIP that addresses NAAQS 
revisions

[[Page 14670]]

pursuant to section 110(a)(2)(D)(i) is an affirmative obligation under 
the CAA and is not dependent upon whether a state is notified of its 
obligation or issued a finding of failure to act as EPA did in 2005.
    If Arkansas had acted promptly in 1997 to address section 
110(a)(2)(D)(i) for ozone and PM2.5, Arkansas would still 
have had to consider RH in its SIP submittal. The visibility provisions 
of the CAA gave notice to the States that they needed to address 
interstate transport of visibility impairing pollutants through RH. 
Back in 1977 when Congress enacted the visibility provisions of the 
CAA, Congress expressed concern with ``haze'' from ``regionally 
distributed sources \228\ '' and concluded that additional provisions 
were needed to ``remedy the visibility problem.'' Congress amended the 
visibility provisions in 1990 to more specifically address interstate 
transport of air pollutants and RH. Section 169B created visibility 
transport regions to address the interstate transport of air pollutants 
from one or more states that contribute significantly to visibility 
impairment in class I areas. Under CAA 169B, each visibility transport 
region would have a visibility transport commission that was required 
to study adverse impacts on visibility and recommend regulations to 
address long range strategies for addressing regional haze. In keeping 
with the visibility provisions of the CAA, EPA has determined that 
states may be able to satisfy the requirements of CAA section 
110(a)(2)(D)(i)(II) with a state relying on the analysis conducted by a 
visibility transport commission to ensure that emissions from sources 
within the state are not interfering with the visibility programs of 
other states, as contemplated in section 110(a)(2)(D)(i)(II) or an 
approved RH SIP.
---------------------------------------------------------------------------

    \228\ H.R. Rep. No. 95-294 at 204 (1977).
---------------------------------------------------------------------------

    Comment: It is an abuse of administrative procedures for EPA to use 
its proposed disapproval of the BART elements of the Arkansas RH SIP as 
the basis for not approving a previous SIP submittal upon which it 
should have already acted. There is no reason to disapprove any portion 
of the previous submittal as the language stating that Arkansas would 
rely on the RH regulations to satisfy the section 110(a)(2)(D)(i)(II) 
is still valid. Therefore, EPA should approve the Arkansas Interstate 
Transport SIP.
    Response: As previously discussed, we are acting on section 
110(a)(2)(D)(i)(II) based on our disapproval of some of the BART 
determinations of the RH SIP submittal since it was Arkansas that 
represented to other CENRAP member states, and included in the CENRAP 
modeling, emissions reductions from BART controls on Arkansas sources 
subject to BART. CENRAP states have relied on those representations in 
developing their RH SIPs and RPGs. If Arkansas cannot deliver those 
emission reductions relied on by other states, those emission 
reductions will interfere with the CENRAP member state visibility 
programs. While the Arkansas Interstate Transport SIP statement that it 
relies on the RH regulations to satisfy the section 110(a)(2)(D)(i)(II) 
is still true, we are obligated to disapprove a portion of the 
Interstate Transport SIP because we are finding that Arkansas is not 
satisfying its obligations under the RH regulations and causing 
emissions from Arkansas to interfere with other states' visibility 
programs.
    Comment: The EPA should approve the Arkansas Interstate Transport 
SIP. In developing their RH SIPs and RPGs, Arkansas and potentially 
impacted states collaborated through the CENRAP. Emission reductions 
for the CENRAP states are scheduled to be fully realized by 2018. 
Presumably, EPA will have approved some version of an Arkansas SIP by 
2013, and any such submittal would have at least the amount of BART 
reductions provided for in current SIP submittals. With a compliance 
schedule of no more than 5 years after EPA approval, these reductions 
would still be realized by 2018.
    Response: Arkansas is assuming that EPA will have approved 
Arkansas's SIP provisions by 2013 that address the promised BART 
emissions reductions to the CENRAP. The EPA cannot base decisions on 
potential future actions. Our rulemaking is limited to the events that 
have occurred at the time of rulemaking. It is not a foregone 
conclusion that Arkansas will submit and EPA will have approved SIP 
provisions with the promised emissions reductions by 2013, much less 
that those emissions reductions would be realized by 2018.
    Comment: In April 2008, Arkansas submitted an Interstate Transport 
SIP revision to address its Good Neighbor CAA obligations triggered by 
the 1997 8-hour ozone and PM2.5 NAAQS. Section 110(k)(1)(B) 
of the CAA requires EPA to act on a SIP revision within 18 months. 
EPA's proposal does not address why EPA violated the statutory deadline 
by waiting nearly two years after the deadline in the CAA to take 
action on Arkansas's April 2008 Interstate Transport SIP submission.
    Response: We acknowledge that we are late in acting on Arkansas's 
Interstate Transport SIP revisions regarding its ``Good Neighbor'' CAA 
obligations triggered by the 1997 8-hour ozone and PM2.5 
NAAQS. We are working diligently to address all of these SIP submittals 
as quickly and expeditiously as possible. With this action today 
finalizing our partial approval and partial disapproval of Arkansas's 
Interstate Transport SIP addressing impairment of other states' 
visibility measures, we are fulfilling our statutory obligation under 
section 110(a)(2)(D)(i)(II) of the CAA.
    Comment: Like Oregon and Colorado, Arkansas submitted an Interstate 
Transport SIP predicated on a RH SIP to address section 
110(a)(2)(D)(i)(II). However, EPA has treated Arkansas differently that 
Oregon and Colorado in meeting the requirements of section 
110(a)(2)(D)(i)(II). For Oregon, despite the discrepancies between what 
was assumed by the RPO and the emission reductions included in Oregon's 
RH SIP, EPA approved the visibility component of Oregon's Interstate 
Transport SIP after reviewing the RPO's photochemical modeling 
emissions projections finding that the emissions reductions included in 
Oregon's RH SIP are ``approximately equal'' to those assumed by 
neighboring states. For Colorado, in evaluating the visibility 
component of Colorado's Interstate Transport SIP, EPA did not consider 
Colorado's RH SIP because it had not been approved. Instead, EPA 
conducted a ``weight-of-evidence'' evaluation to assess the increase in 
Colorado sulfates and nitrates emissions above what neighboring states 
assumed, and concluded that ``Colorado has a minimal impact on 
visibility'' at Class I areas in neighboring states. There is no 
indication that EPA performed such analyses in its evaluation of the 
visibility component of the Arkansas Interstate Transport SIP, and 
instead held that any discrepancy between the emissions reductions 
included in a state's RH SIP and the emissions reductions assumed by 
neighboring states is equivalent to ``interfering'' with the measures 
of other states to protect visibility. This is similar to EPA's 
interpretation of the visibility component of the Good Neighbor 
Provision in its evaluations of the Interstate Transport SIPs for New 
Mexico, Oklahoma, and North Dakota. The EPA has failed to identify a 
threshold of deviation from the CENRAP assumptions in a state's RH SIP 
in order to trigger disapproval of visibility provisions of a state's

[[Page 14671]]

Interstate Transport SIP. In addition, the EPA has also failed to 
address why the criteria EPA used to evaluate the visibility component 
of Arkansas's Interstate Transport SIP is different from that used to 
evaluate the Interstate Transport SIPs of other states, in particular 
those of Oregon and Colorado.
    Response: The EPA disagrees that our proposed action on the 
visibility component of Arkansas's Interstate Transport SIP is 
inconsistent with our actions on the Interstate Transport SIPs of 
Oregon and Colorado. As described in the comment, EPA approved the 
visibility component of Oregon's Interstate Transport SIP after 
reviewing the RPO's photochemical modeling emissions projections and 
finding that the emissions reductions included in Oregon's RH SIP are 
``approximately equal'' to those assumed by neighboring states. In the 
case of Arkansas, we are disapproving nearly all of the State's BART 
determinations for SO2 and NOX (and some PM) 
emissions limits that Arkansas promised as part of its membership to 
the CENRAP. Those emissions limits have been included in the 2018 
CENRAP modeling, and other states are relying on this modeling in 
developing their RPGs and RH SIPs. However, as discussed previously, 
with our disapproval, these anticipated reductions will not be taking 
place and thus the emissions of SO2, NOX and PM 
from Arkansas will interfere with other states' visibility programs. 
With the disapproval of certain BART determinations and Arkansas's 
promised BART emissions reductions included in the CENRAP process, 
there is a large discrepancy between the RPO's photochemical modeling 
emissions projections (which is reflective of the emissions reductions 
other states relied on in their RH SIPs) and the emissions reductions 
that will actually be taking place (i.e. the State's BART 
determinations that we find satisfy the RH requirements).
    The comment points out that EPA did not consider Colorado's RH SIP 
in evaluating the visibility component of Colorado's Interstate 
Transport SIP because it had not been approved yet. EPA points out that 
at the time we approved Colorado's Interstate Transport SIP, we had not 
taken any kind of action on the Colorado RH SIP. In fact, we haven't 
taken any kind of action on the Colorado RH SIP to date. Therefore, in 
order to take an informed and appropriate action on the Colorado 
Interstate Transport SIP, EPA conducted a ``weight-of-evidence'' 
evaluation to assess the increase in Colorado sulfates and nitrates 
emissions above what neighboring states assumed. Based on the results 
of that evaluation, we concluded that Colorado has a minimal impact on 
visibility at Class I areas in neighboring states. This is not the case 
with Arkansas. As explained in Appendix A to the TSD for our proposed 
rulemaking on the Arkansas RH SIP, the CENRAP's photochemical modeling 
clearly shows that Arkansas emissions are causing visibility impairment 
at the Hercules Glades and Mingo Class I areas in Missouri. As 
explained above, we proposed to disapprove nearly all of Arkansas's 
SO2 and NOX (and some PM) BART determinations. In 
light of the large number (and percentage) of SO2 and 
NOX emissions reductions that other states relied on, we do 
not believe that it is necessary at this time to do any other analysis 
to further support our partial disapproval of the visibility component 
of Arkansas's Interstate Transport SIP since Arkansas has promised 
emissions reductions for subject to BART sources, and included them in 
the CENRAP modeling that other states are relying on in developing 
their RPGs and RH SIPs, but the emissions reductions for the 
disapproved BART determinations will not occur.
    Comment: None of the BART determinations in the Arkansas RH SIP 
should be approved by EPA, and accordingly EPA should fully disapprove 
the Arkansas Interstate Transport SIP for visibility protection. In 
2018, the contribution from Arkansas sources to visibility impairment 
in other states (including Missouri and Oklahoma) are projected to 
increase from 2002 levels. In recognition of this, the State of 
Oklahoma asked for additional emission reductions from Arkansas 
sources, but Arkansas did not agree that any further emissions 
reductions were necessary (2007 Letter from ADEQ to ODEQ, Appendix 11.2 
of Arkansas RH SIP). Therefore, it is unlikely that the BART emission 
limits adopted by Arkansas are sufficient to ensure that sources in 
Arkansas will not interfere with Oklahoma's ability to ensure 
reasonable progress toward attaining the national visibility goal at 
the Wichita Mountains Class I area.
    Response: Arkansas proposed to comply with the requirements of the 
Interstate Transport SIP for visibility protection through reductions 
in emissions from BART eligible sources. This is in keeping with the 
CAA and is acceptable to EPA. As explained above, we are partially 
disapproving Arkansas's Interstate Transport SIP for visibility 
protection because Arkansas proposed to meet these requirements through 
the BART determinations that we are disapproving and therefore the 
relied-upon emissions reductions will not occur. The comment is right 
that in 2018, the contribution from Arkansas sources to visibility 
impairment in other states (including Oklahoma and Missouri) is 
projected to increase from 2002 levels though minimally. However, those 
projected emissions increases are due to Arkansas's planned building of 
new facilities which will emit visibility impairing pollutants. The EPA 
does note that one of the proposed plants included in this projection 
has recently been cancelled and thus Arkansas projected emissions 
increases for 2018 will be less than projected in their RH SIP.
    For purposes of noninterference with other states' visibility 
programs, Arkansas met with other regional states and promised that it 
would contribute a certain portion of the emissions reductions to 
address RH for the region. Although Oklahoma initially believed that 
emissions from Arkansas sources are impacting visibility at Wichita 
Mountains and that it might be necessary for Arkansas to commit to 
additional emissions reductions, Arkansas responded to ODEQ's concerns 
with a letter dated August 17, 2007, explaining that based on 
photochemical modeling, ADEQ had calculated that the total visibility 
impact from all sources in Arkansas at Wichita Mountains is 0.2 
dv.\229\ Furthermore, in section X.A. of the Oklahoma RH SIP submitted 
to EPA, ODEQ references the August 17, 2007 letter sent by ADEQ and 
states that it is in agreement with the projected emissions reductions 
from Arkansas and all other states with which it consulted with regard 
to visibility impairment at Wichita Mountains. For Missouri's 
consultation with Arkansas regarding emissions reductions, Arkansas and 
Missouri met in a joint consultation (see our TSD and Arkansas RH SIP), 
where both states agreed upon the amount of emission reductions each 
state would provide in order for both states to meet the visibility 
requirements of the CAA. All the states Arkansas consulted with 
accepted Arkansas's committed emissions reductions and have based their 
RPGs and RH SIPs accordingly with the idea that regional states can 
attain natural visibility conditions for class I areas within their 
boundaries by 2064 based off of this information. This

[[Page 14672]]

is consistent with the intent of the visibility program under the CAA 
to allow the states under a regional planning committee to determine 
the best way to address visibility impairment for the region. 
Therefore, we find that partially approving and partially disapproving 
Arkansas's Interstate Transport SIP with regards to interference with 
other states' visibility measures is appropriate since Arkansas, 
working in conjunction with other states in the regional planning 
organization, committed to certain emissions reductions of subject to 
BART sources which Arkansas can no longer meet because we are 
disapproving a portion of Arkansas's BART determinations, and therefore 
the relied-upon emissions reductions will not occur.
---------------------------------------------------------------------------

    \229\ See letter from Mike Bates, Air Division Director, 
Arkansas Department of Environmental Quality, to Eddie Terrill, Air 
Division Director, Oklahoma Department of Environmental Quality, 
dated August 17, 2007. This letter is found in Appendix 10.3 of the 
Arkansas RH SIP.
---------------------------------------------------------------------------

H. Other Comments

    Comment: EPA did not propose a FIP concurrently with its proposal 
to partially disapprove the Arkansas RH SIP, thus being inconsistent 
with what EPA has recently proposed for other states. When EPA proposed 
to partially approve and partially disapprove the RH SIPs of North 
Dakota and Oklahoma, at the same time EPA proposed FIP requirements for 
the components of the RH SIP that EPA proposed to disapprove (see 76 FR 
58570 and 76 FR 16168). Arkansas submitted its RH SIP earlier than most 
other states, including at least 18 months before North Dakota and 
Oklahoma, yet EPA did not propose a FIP concurrently with its proposed 
partial disapproval of the Arkansas RH SIP and it appears it will be 
several years before the facilities in the State that are contributing 
to regional haze install pollution controls and reduce emissions. The 
residents and visitors to the State of Arkansas are getting the short 
shrift from EPA compared to the residents and visitors of these other 
states. This is very important considering that the majority of 
Arkansas's coal-fired power plants have absolutely no SO2 
controls, and at this point it is not clear that the units will be 
subject to any regulations other than BART that would require the 
installation of scrubbers. EPA should not delay any longer in proposing 
a FIP to address RH in Arkansas.
    Response: While we appreciate the concerns described in the comment 
regarding visibility impairment in Arkansas's Class I areas, we note 
that the CAA section 110(c) requires that EPA promulgate a FIP at any 
time within 2 years after EPA disapproves a SIP in whole or in part. As 
explained in our proposed rulemaking, at this time we are not 
promulgating a FIP for the portions of the Arkansas RH SIP we are 
disapproving because ADEQ has expressed its intent to revise the 
Arkansas RH SIP by correcting the deficiencies in the SIP. We are 
electing to not promulgate a FIP at this time in order to provide 
Arkansas time to correct these deficiencies. While EPA has promulgated 
FIPs concurrently to address the deficiencies of states' RH SIPs, there 
is no statutory requirement for EPA to do so. Unless we receive a SIP 
revision from the State that addresses the flaws we identified in our 
proposed rulemaking and in this final action and satisfies all the 
regulatory and statutory requirements and we approve it within 2 years 
of our final partial disapproval of the Arkansas RH SIP, EPA is 
required to promulgate a FIP within 2 years of our final partial 
disapproval of the SIP to address the components of the SIP we 
disapproved.
    Comment: The State is required to document the technical basis, 
including modeling, monitoring, and emissions information, on which the 
State is relying to determine its apportionment of emission reduction 
obligations necessary for achieving reasonable progress in each 
mandatory Class I Federal area it affects (see 40 CFR 
51.308(d)(3)(iii)). Arkansas relied on the CENRAP modeling and emission 
inventories to meet this requirement, and therefore Arkansas itself did 
not provide much of the technical basis for the modeling and emission 
inventories. EPA has posted some of the relevant CENRAP documents to 
its docket for the Arkansas RH rulemaking, but not all relevant 
documents have been provided. There is one document of facility-
specific emission projections for 2018 we wanted to evaluate but were 
unable to locate. Only graphical representations of each state's 
emissions by source category are provided in the Technical Support 
Document for the CENRAP modeling. The CENRAP Web site is no longer 
being maintained and no emission inventory documents are available on 
that site. We contacted EPA Region 6 to obtain this document, but EPA 
was unable to locate it. A review of the 2018 facility-specific 
emission inventory is imperative in reviewing the 2018 modeling 
projections and the LTS for Arkansas as well as the LTS of other CENRAP 
states to determine if the LTS for those states include enforceable 
emission limitations that correspond to the 2018 emissions projections 
for each facility. A review of the 2018 facility-specific emissions 
inventory is also necessary to determine whether all visibility-
impairing sources were modeled and whether the emissions modeled for 
all sources were reasonable given the emission reduction requirements 
on the books and forthcoming by 2018. EPA should not approve the 
Arkansas RH SIP because it does not include the technical basis that 
Arkansas is relying on to show that it will achieve reasonable progress 
towards reaching natural background visibility conditions at its Class 
I areas. Also, EPA should not be proposing to find the 2018 emissions 
inventory ``acceptable,'' when it does not have the facility-specific 
emission projections for 2018.
    Response: The full reference to 40 CFR 51.308(d)(3)(iii) is the 
following:

    ``The State must document the technical basis, including 
modeling, monitoring and emissions information, on which the State 
is relying to determine its apportionment of emission reduction 
obligations necessary for achieving reasonable progress in each 
mandatory Class I Federal area it affects. The State may meet this 
requirement by relying on technical analyses developed by the 
regional planning organization and approved by all State 
participants. The State must identify the baseline emissions 
inventory on which its strategies are based. The baseline emissions 
inventory year is presumed to be the most recent year of the 
consolidated periodic emissions inventory.''

    A full reading of 40 CFR 51.308(d)(3)(iii) demonstrates that the 
requirement for the State to document the technical basis on which it 
is relying to determine its apportionment of emission reduction 
obligations necessary for achieving reasonable progress in each 
mandatory Class I Federal area it affects is to ensure that potentially 
affected states have all the technical information they need to be able 
to determine whether they agree with the State's apportionment of 
emission reduction obligations. As pointed out in the comment, Arkansas 
elected to meet the requirement under 40 CFR 51.308(d)(3)(iii) to 
document the technical basis for its RH SIP by relying on technical 
analyses developed by the CENRAP and approved by all State 
participants. Through the CENRAP process, all affected states agreed 
with Arkansas's apportionment of emission reduction obligations and 
these were included in the CENRAP 2018 emissions inventory modeling on 
which all the CENRAP member states are relying on to develop their RPGs 
and LTS. Since the technical analyses developed by the RPOs are often 
very extensive, it would be unreasonable to expect states to include 
all these documents as part of their RH SIPs. Since Arkansas relied on 
technical analyses developed by the CENRAP and approved by all State 
participants and properly identified the baseline

[[Page 14673]]

emissions inventory on which its strategies are based, the State 
satisfied the requirements under 40 CFR 51.308(d)(3)(iii). This is 
supported by 2018 CENRAP modeling data results indicating that two 
Class I areas outside of Arkansas (Missouri Class I areas--Mingo 
Wilderness Area and Hercules Glades Wilderness Area), where Arkansas 
sources have a significant impact, are projected to achieve the RPGs in 
2018.
    During the comment period, we provided the commenter with most of 
the information requested (including all the emission summary 
spreadsheet files we had), with the exception of two emission inventory 
summary files. Unfortunately, the document of facility-specific 
emission projections for 2018 referenced in the comment consists of two 
SMOKE electronic emissions processing reports that can be viewed in a 
very large electronic database using database software. However, these 
reports are too large to export to a spreadsheet, as had been done to 
generate other reports within the database, because it includes the 
daily point emissions by facility projected in 2018 for all the 
facilities in the CENRAP states. We had most of the SMOKE emission 
reports, which we did provide to the commenter's contractor. We did not 
consider these few missing emission reports to be critical or necessary 
to our review because we realized for reasons outside of the data 
contained in the missing reports that we would have to propose partial 
disapproval of the Arkansas RH SIP (including LTS and BART 
determinations). It is not practical to require that the State submit 
or include every possible electronic file that supports the RPO 
modeling as this is several Terabytes of data and most of the data has 
been submitted or is posted on Web sites or ftp sites or available on 
request. We believe this is the only practical way to address the large 
volumes of data necessary for the development of multistate regional 
haze modeling analysis. Unfortunately, as noted in the comment, the 
CENRAP Web site is no longer being maintained and no emission inventory 
documents are available on that site. In general, the former CENRAP 
members have been very supportive in providing information when 
requested. It was only due to specific issues that we were not able to 
provide the information for these two SMOKE emission reports when 
requested. We will continue to work to address this issue as we work 
with Arkansas on development of an approvable Regional Haze SIP. Again 
we do not believe that these particular files were critical or 
necessary to our conclusion that the Arkansas SIP should be partially 
approved and partially disapproved.

I. Comments Requesting an Extension to the Public Comment Period

    We received several comments requesting that the comment period be 
extended by an additional 60 days.
    Response: Originally the comment period for our proposal was 
scheduled to close on November 16, 2011. In response to requests we 
extended the public comment period to December 22, 2011. In doing so, 
we took into consideration how an extension might affect our ability to 
consider comments received on the proposed action and still comply with 
the terms of a consent decree we have with Sierra Club.\230\
---------------------------------------------------------------------------

    \230\ Sierra Club v. Lisa Jackson, Case No. 1:10-CV-02112-JEB.
---------------------------------------------------------------------------

IV. Statutory and Executive Order Reviews

    Under the Clean Air Act, the Administrator is required to approve a 
SIP submission that complies with the provisions of the Act and 
applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). 
Thus, in reviewing SIP submissions, EPA's role is to act on state law 
as meeting Federal requirements and does not impose additional 
requirements beyond those imposed by state law.

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is not a ``significant regulatory action'' under the 
terms of Executive Order 12866 (58 FR 51735, October 4, 1993) and is 
therefore not subject to review under Executive Orders 12866 and 13563 
(76 FR 3821, January 21, 2011).

B. Paperwork Reduction Act

    This action does not impose an information collection burden under 
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq, 
because this SIP action under section 110 of the CAA will not in-and-of 
itself create any new information collection burdens but simply 
approves or disapproves certain State requirements for inclusion into 
the SIP. Burden is defined at 5 CFR 1320.3(b).

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency 
to conduct a regulatory flexibility analysis of any rule subject to 
notice and comment rulemaking requirements unless the agency certifies 
that the rule will not have a significant economic impact on a 
substantial number of small entities. Small entities include small 
businesses, small not-for-profit enterprises, and small governmental 
jurisdictions. For purposes of assessing the impacts of today's rule on 
small entities, small entity is defined as: (1) A small business as 
defined by the Small Business Administration's (SBA) regulations at 13 
CFR 121.201; (2) a small governmental jurisdiction that is a government 
of a city, county, town, school district or special district with a 
population of less than 50,000; and (3) a small organization that is 
any not-for-profit enterprise which is independently owned and operated 
and is not dominant in its field.
    After considering the economic impacts of today's rule on small 
entities, I certify that this action will not have a significant impact 
on a substantial number of small entities. This rule does not impose 
any requirements or create impacts on small entities. This SIP action 
under section 110 of the CAA will not in-and-of itself create any new 
requirements but simply approves or disapproves certain State 
requirements for inclusion into the SIP. Accordingly, it affords no 
opportunity for EPA to fashion for small entities less burdensome 
compliance or reporting requirements or timetables or exemptions from 
all or part of the rule. The fact that the CAA prescribes that various 
consequences (e.i. emission limitations) may or will flow from this 
action does not mean that EPA either can or must conduct a regulatory 
flexibility analysis for this action. Therefore, this action will not 
have a significant economic impact on a substantial number of small 
entities.

D. Unfunded Mandates Reform Act

    This action contains no Federal mandates under the provisions of 
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), 2 U.S.C. 
1531-1538 for State, local, or tribal governments or the private 
sector. EPA has determined that the disapproval action does not include 
a Federal mandate that may result in estimated costs of $100 million or 
more to either State, local, or tribal governments in the aggregate, or 
to the private sector. This action merely approves or disapproves pre-
existing requirements under State or local law, and imposes no new 
requirements. Accordingly, no additional costs to State, local, or 
tribal governments, or to the private sector, result from this action.

[[Page 14674]]

E. Executive Order 13132, Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August 
10, 1999), requires EPA to develop an accountable process to ensure 
``meaningful and timely input by State and local officials in the 
development of regulatory policies that have federalism implications.'' 
``Policies that have federalism implications'' is defined in the 
Executive Order to include regulations that have ``substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government.''
    This action does not have federalism implications. It will not have 
substantial direct effects on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government, as 
specified in Executive Order 13132, because it merely approves or 
disapproves certain State requirements for inclusion into the SIP and 
does not alter the relationship or the distribution of power and 
responsibilities established in the CAA. Thus, Executive Order 13132 
does not apply to this action.

F. Executive Order 13175, Coordination With Indian Tribal Governments

    This action does not have tribal implications, as specified in 
Executive Order 13175 (65 FR 67249, November 9, 2000), because the SIP 
submittals EPA is approving or disapproving would not apply in Indian 
country located in the state, and EPA notes that it will not impose 
substantial direct costs on tribal governments or preempt tribal law. 
Thus, Executive Order 13175 does not apply to this action.

G. Executive Order 13045, Protection of Children From Environmental 
Health Risks and Safety Risks

    EPA interprets Executive Order 13045 (62 FR 19885, April 23, 1997) 
as applying only to those regulatory actions that concern health or 
safety risks, such that the analysis required under section 5-501 of 
the Executive Order has the potential to influence the regulation. This 
action is not subject to Executive Order 13045 because it because it is 
not an economically significant regulatory action based on health or 
safety risks subject to Executive Order 13045 (62 FR 19885, April 23, 
1997). This SIP action under section 110 of the CAA will not in-and-of 
itself create any new regulations but simply approves or disapproves 
certain State requirements for inclusion into the SIP.

H. Executive Order 13211, Actions That Significantly Affect Energy 
Supply, Distribution or Use

    This action is not subject to Executive Order 13211 (66 FR 28355, 
May 22, 2001) because it is not a significant regulatory action under 
Executive Order 12866.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (``NTTAA''), Public Law 104-113, section 12(d) (15 U.S.C. 
272 note) directs EPA to use voluntary consensus standards in its 
regulatory activities unless to do so would be inconsistent with 
applicable law or otherwise impractical. Voluntary consensus standards 
are technical standards (e.g., materials specifications, test methods, 
sampling procedures, and business practices) that are developed or 
adopted by voluntary consensus standards bodies. NTTAA directs EPA to 
provide Congress, through OMB, explanations when the Agency decides not 
to use available and applicable voluntary consensus standards.
    The EPA believes that this action is not subject to requirements of 
section 12(d) of NTTAA because application of those requirements would 
be inconsistent with the CAA.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    Executive Order 12898 (59 FR 7629 (Feb. 16, 1994)) establishes 
Federal executive policy on environmental justice. Its main provision 
directs Federal agencies, to the greatest extent practicable and 
permitted by law, to make environmental justice part of their mission 
by identifying and addressing, as appropriate, disproportionately high 
and adverse human health or environmental effects of their programs, 
policies, and activities on minority populations and low-income 
populations in the United States.
    EPA lacks the discretionary authority to address environmental 
justice in this action. In reviewing SIP submissions, EPA's role is to 
approve or disapprove state choices, based on the criteria of the CAA. 
Accordingly, this action merely approves or disapproves certain State 
requirements for inclusion into the SIP under section 110 of the CAA 
and will not in-and-of itself create any new requirements. Accordingly, 
it 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.

K. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. EPA will submit a report containing this action and 
other required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This action is not a ``major rule'' as defined by 5 U.S.C. 
804(2). This rule will be effective on April 11, 2012.

L. Judicial Review

    Under section 307(b)(1) of the CAA, petitions for judicial review 
of this action must be filed in the United States Court of Appeals for 
the appropriate circuit by May 11, 2012. Filing a petition for 
reconsideration by the Administrator of this final rule does not affect 
the finality of this action for the purposes of judicial review nor 
does it extend the time within which a petition for judicial review may 
be filed, and shall not postpone the effectiveness of such rule or 
action. This action may not be challenged later in proceedings to 
enforce its requirements. See CAA section 307(b)(2).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Nitrogen dioxide, Ozone, 
Particulate matter, Reporting and recordkeeping requirements, Sulfur 
dioxides, Visibility, Interstate transport of pollution, Regional haze, 
Best available retrofit technology.

    Dated: February 13, 2012.
Al Armendariz,
Regional Administrator, Region 6.
    40 CFR part 52 is amended as follows:

PART 52--[AMENDED]

0
1. The authority citation for part 52 continues to read as follows:

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

[[Page 14675]]

Subpart E--[Amended]

0
2. Section 52.170 is amended:
0
a. In paragraph (c), under the first table entitled ``EPA-Approved 
Regulations in the Arkansas SIP,'' by revising the heading for Chapter 
15 under Regulation No. 19 to read ``Regional Haze''; by revising the 
entry for Reg. 19.1501; and by adding new entries in numerical order 
for Reg. 19.1502, Reg. 19.1503, Reg. 19.1504, Reg. 19.1505, Reg. 
19.1506, and Reg. 19.1507.
0
b. In paragraph (e), under the third table entitled ``EPA-Approved Non-
Regulatory Provisions and Quasi-Regulatory Measures in the Arkansas 
SIP'', by adding at the end of the table a new entry for ``Interstate 
Transport for the 1997 ozone and PM2.5 NAAQS'' immediately 
followed by a new entry for ``Regional Haze SIP''.
    The amendments read as follows:

Sec.  52.170  Identification of plan.

* * * * *
    (c) * * *

                                                      EPA-Approved Regulations in the Arkansas SIP
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                State approval/
           State citation                 Title/subject         effective  date      EPA approval date                      Explanation
--------------------------------------------------------------------------------------------------------------------------------------------------------
                             Regulation No. 19: Regulations of the Arkansas Plan of Implementation for Air Pollution Control
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                Chapter 15: Regional Haze
--------------------------------------------------------------------------------------------------------------------------------------------------------
Reg. 19.1501.......................  Purpose...............  1/25/2009...........  3/12/2012 [Insert FR   ..............................................
                                                                                    page number where
                                                                                    document begins].
Reg, 19.1502.......................  Definitions...........  1/25/2009...........  3/12/2012 [Insert FR   ..............................................
                                                                                    page number where
                                                                                    document begins].
Reg. 19.1503.......................  BART Eligible Sources.  1/25/2009...........  3/12/2012 [Insert FR   ..............................................
                                                                                    page number where
                                                                                    document begins].
Reg. 19.1504.......................  Facilities Subject-to-  1/25/2009...........  3/12/2012 [Insert FR   Under (A): The identification of sources
                                      BART.                                         page number where      subject to BART is approved, except for not
                                                                                    document begins].      identifying the 6A and 9A Boilers at the
                                                                                                           Georgia Pacific Crossett Mill, which we find
                                                                                                           are subject to BART.
                                                                                                          Under (B): The requirement for BART
                                                                                                           installation and operation as expeditiously
                                                                                                           as practicable, but no later than 5 years
                                                                                                           after EPA approval is partially approved and
                                                                                                           partially disapproved, such that the partial
                                                                                                           approval is for the BART determinations we
                                                                                                           are approving and the partial disapproval is
                                                                                                           for the BART determinations we are
                                                                                                           disapproving; and the requirement for BART
                                                                                                           installation and operation no later than 6
                                                                                                           years after the effective date of the State
                                                                                                           regulation is disapproved.
Reg. 19.1505.......................  BART Requirements.....  1/25/2009...........  3/12/2012 [Insert FR   The following portions of Reg. 19.1505 are
                                                                                    page number where      disapproved: (A)(1) and (2), (B), (C), (D)(1)
                                                                                    document begins].      and (2), (E), (F)(1) and (2), (G)(1) and (2),
                                                                                                           (H), (I)(1) and (2), (J)(1) and (2), (K),
                                                                                                           (L), (M)(1), and (N).
Reg. 19.1506.......................  Compliance Provisions.  1/25/2009...........  3/12/2012 [Insert FR   The requirement to demonstrate compliance with
                                                                                    page number where      the BART limits listed in Reg. 19.1505 (A)(1)
                                                                                    document begins].      and (2), (B), (C), (D)(1) and (2), (E),
                                                                                                           (F)(1) and (2), (G)(1) and (2), (H), (I)(1)
                                                                                                           and (2), (J)(1) and (2), (K), (L), (M)(1),
                                                                                                           and (N) is disapproved.
Reg. 19.1507.......................  Permit Reopening......  1/25/2009...........  3/12/2012 [Insert FR   ..............................................
                                                                                    page number where
                                                                                    document begins].
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------

* * * * *
    (e) * * *
* * * * *

[[Page 14676]]

            EPA-Approved Non-Regulatory Provisions and Quasi-Regulatory Measures in the Arkansas SIP
----------------------------------------------------------------------------------------------------------------
                                                            State
                                        Applicable        submittal/
      Name of SIP provision            geographic or      effective    EPA approval  date        Explanation
                                    nonattainment  area      date
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
Interstate Transport for the 1997  Statewide...........    3/28/2008  3/12/2012 [Insert FR  Noninterference with
 ozone and PM2.5 NAAQS                                                 page number where     measures required
 (Noninterference with measures                                        document begins].     to protect
 required to protect visibility                                                              visibility in any
 in any other State).                                                                        other State
                                                                                             partially approved
                                                                                             3/12/12.
Regional Haze SIP................  Statewide...........   9/23/2008,  3/12/2012 [Insert FR  The following
                                                            8/3/2010   page number where     portions are
                                                                       document begins].     partially approved
                                                                                             and partially
                                                                                             disapproved:
    (a) Identification of                                                                   (a) Identification
     affected Class I areas.                                                                 of best available
                                                                                             retrofit technology
                                                                                             (BART) eligible
                                                                                             sources and subject
                                                                                             to BART sources;
    (b) Determination of baseline                                                           (b) requirements for
     and natural visibility                                                                  best available
     conditions.                                                                             retrofit technology
                                                                                             (BART);
    (c) Determination of the                                                                (c) the Arkansas
     Uniform Rate of Progress.                                                               Regional Haze Rule;
                                                                                             and
    (d) Reasonable progress goal                                                            (d) Long Term
     consultation and long term                                                              Strategy. (See Sec.
     strategy consultation.                                                                    52.173(a)).
    (e) Coordination regional
     haze and reasonably
     attributable visibility
     impairment.
    (f) Monitoring Strategy and
     other implementation
     requirements.
    (g) Commitment to submit
     periodic Regional Haze SIP
     revisions and periodic
     progress reports describing
     progress towards the
     reasonable progress goals.
    (h) Commitment to make a
     determination of the
     adequacy of the existing SIP
     at the time a progress
     report is submitted.
    (i) Coordination with States
     and Federal Land Managers.
    (j) The following best
     available retrofit
     technology (BART)
     determinations: PM BART
     determination for the AEP
     Flint Creek Plant Boiler No.
     1; SO2 and PM BART
     determinations for the
     natural gas firing scenario
     for the Entergy Lake
     Catherine Plant Unit 4; PM
     BART determinations for both
     the bituminous and sub-
     bituminous coal firing
     scenarios for the Entergy
     White Bluff Plant Units 1
     and 2; and PM BART
     determination for the Domtar
     Ashdown Mill Power Boiler
     No. 1.
----------------------------------------------------------------------------------------------------------------

0
3. Section 52.173 is added to read as follows:

Sec.  52.173  Visibility protection.

    (a) Regional haze. The regional haze State Implementation Plan 
(SIP) revisions submitted on September 23, 2008 and August 3, 2010, and 
supplemented on September 27, 2011 are partially approved and partially 
disapproved.
    (1) The identification of sources that are eligible for Best 
Available Retrofit Technology (BART) is approved, with the exception of 
the 6A Boiler at the Georgia-Pacific Crossett Mill, which is BART 
eligible.
    (2) The identification of sources subject to BART is approved, with 
the exception of the 6A and 9A Boilers at the Georgia-Pacific Crossett 
Mill, which are both subject to BART.
    (3) The following BART determinations are disapproved:
    (i) The sulfur dioxide (SO2), nitrogen dioxide 
(NOX), and particulate matter

[[Page 14677]]

(PM) BART determinations for the Arkansas Electric Cooperative 
Corporation Bailey Plant Unit 1 and the AECC McClellan Plant Unit 1;
    (ii) The SO2 and NOX BART determinations for 
the American Electric Power Flint Creek Plant Boiler No. 1;
    (iii) The NOX BART determination for the natural gas 
firing scenario and the SO2, NOX, and PM BART 
determinations for the fuel oil firing scenario for the Entergy Lake 
Catherine Plant Unit 4;
    (iv) The SO2 and NOX BART determinations for 
both the bituminous and sub-bituminous coal firing scenarios for the 
Entergy White Bluff Plant Units 1 and 2;
    (v) The BART determination for the Entergy White Bluff Plant 
Auxiliary Boiler;
    (vi) The SO2 and NOX BART determinations for 
the Domtar Ashdown Mill Power Boiler No. 1; and
    (vii) The SO2, NOX and PM BART determinations 
for the Domtar Ashdown Mill Power Boiler No. 2.
    (4) The Arkansas Regional Haze Rule, (APCEC Regulation 19, Chapter 
15), is partially approved and partially disapproved such that:
    (i) The requirement under Reg. 19.104(B) for BART installation and 
operation as expeditiously as practicable, but no later than 5 years 
after EPA approval of the Arkansas Regional Haze State Implementation 
Plan is partially approved and partially disapproved, such that the 
partial approval is for the BART determinations we are approving and 
the partial disapproval is for the BART determinations we are 
disapproving;
    (ii) The requirement under Reg. 19.1504(B) for BART installation 
and operation no later than 6 years after the effective date of the 
State regulation is disapproved;
    (iii) Reg. 19.1505 (A)(1) and (2), (B), (C), (D)(1) and (2), (E), 
(F)(1) and (2), (G)(1) and (2), (H), (I)(1) and (2), (J)(1) and (2), 
(K), (L), (M)(1), and (N) are disapproved;
    (iv) the Reg. 19.1506 requirement to demonstrate compliance with 
the BART limits listed in Reg. 19.1505 (A)(1) and (2), (B), (C), (D)(1) 
and (2), (E), (F)(1) and (2), (G)(1) and (2), (H), (I)(1) and (2), 
(J)(1) and (2), (K), (L), (M)(1), and (N) is disapproved; and
    (v) The remaining portions are approved.
    (5) The regional haze long term strategy under 40 CFR 51.308(d)(3) 
is partially approved and partially disapproved.
    (6) The reasonable progress goals are disapproved.
    (b) Interstate Transport. The portion of the SIP pertaining to 
adequate provisions to prohibit emissions from interfering with 
measures required in another state to protect visibility, submitted on 
March 28, 2008, and supplemented on September 27, 2011, is partially 
approved and partially disapproved.
    (1) The Arkansas Regional Haze Rule, (APCEC Regulation 19, Chapter 
15), is partially approved and partially disapproved such that:
    (i) The requirement under Reg. 19.104(B) for BART installation and 
operation as expeditiously as practicable, but no later than 5 years 
after EPA approval of the Arkansas Regional Haze State Implementation 
Plan is partially approved and partially disapproved, such that the 
partial approval is for the BART determinations we are approving and 
the partial disapproval is for the BART determinations we are 
disapproving;
    (ii) The requirement under Reg. 19.1504(B) for BART installation 
and operation no later than 6 years after the effective date of the 
State regulation is disapproved;
    (iii) Reg. 19.1505 (A)(1) and (2), (B), (C), (D)(1) and (2), (E), 
(F)(1) and (2), (G)(1) and (2), (H), (I)(1) and (2), (J)(1) and (2), 
(K), (L), (M)(1), and (N) are disapproved;
    (iv) The Reg. 19.1506 requirement to demonstrate compliance with 
the BART limits listed in Reg. 19.1505 (A)(1) and (2), (B), (C), (D)(1) 
and (2), (E), (F)(1) and (2), (G)(1) and (2), (H), (I)(1) and (2), 
(J)(1) and (2), (K), (L), (M)(1), and (N) is disapproved; and
    (v) The remaining portions are approved.

[FR Doc. 2012-4493 Filed 3-9-12; 8:45 am]
BILLING CODE 6560-50-P
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