Approval, and Promulgation of Air Quality Implementation Plans; Indiana; Redesignation of the Evansville Area to Attainment of the Fine Particulate Matter Standard, 29695-29706 [2011-12609]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 76, Number 99 (Monday, May 23, 2011)]
[Proposed Rules]
[Pages 29695-29706]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-12609]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R05-OAR-2008-0396; FRL-9307-1]


Approval, and Promulgation of Air Quality Implementation Plans; 
Indiana; Redesignation of the Evansville Area to Attainment of the Fine 
Particulate Matter Standard

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: On April 3, 2008, the Indiana Department of Environmental 
Management (IDEM) submitted a request for EPA to approve the 
redesignation of the Evansville, Indiana nonattainment area to 
attainment of the 1997 annual fine particulate matter 
(PM2.5) standard. The air quality improvement in this area 
and maintenance of the standard in this area is attributable in 
substantial part to power plant emission reductions in the Eastern 
United States prompted by the Clean Air Interstate Rule (CAIR). The 
United States Court of Appeals for the District of Columbia Circuit 
(D.C. Circuit) has remanded CAIR, but EPA has proposed a replacement 
rule known as the Transport Rule. The Evansville area has attained the 
standard with only a fraction of the reductions that the proposed 
Transport Rule proposed to require. Therefore, EPA is proposing to 
approve the redesignation request for the Evansville area, along with 
related SIP revisions, if and when EPA takes final action to promulgate 
the Transport Rule, provided that the final Transport Rule requires 
emission reductions that are at least substantially equivalent to those 
of the proposed Transport Rule for purposes of maintaining the standard 
in the Evansville area.

DATES: Comments must be received on or before June 22, 2011.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2008-0396, by one of the following methods:
    1. https://www.regulations.gov: Follow the on-line instructions for 
submitting comments.
    2. E-mail: mooney.john@epa.gov.
    3. Fax: (312) 692-2551.
    4. Mail: John M. Mooney, Chief, Air Programs Branch (AR-18J), U.S. 
Environmental Protection Agency, 77 West Jackson Boulevard, Chicago, 
Illinois 60604.
    5. Hand Delivery: John M. Mooney, Chief, Air Programs Branch (AR-
18J), U.S. Environmental Protection Agency, 77 West Jackson Boulevard, 
Chicago, Illinois 60604. Such deliveries are only accepted during the 
Regional Office normal hours of operation, and special arrangements 
should be made for deliveries of boxed information. The Regional Office 
official hours of business are Monday through Friday, 8:30 a.m. to 4:30 
p.m. excluding Federal holidays.
    Instructions: Direct your comments to Docket ID No. EPA-R05-OAR-
2008-0396. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available online at 
https://www.regulations.gov, including any personal information 
provided, unless the comment includes information claimed to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Do not submit information that you 
consider to be CBI or otherwise protected through https://www.regulations.gov or e-mail. The https://www.regulations.gov Web site 
is an ``anonymous access'' system, which means EPA will not know your 
identity or contact information unless you provide it in the body of 
your comment. If you send an e-mail comment directly to EPA without 
going through https://www.regulations.gov your e-mail address will be 
automatically captured and included as part of the comment that is 
placed in the public docket and made available on the Internet. If you 
submit an electronic comment, EPA recommends that you include your name 
and other contact information in the body of your comment and with any 
disk or CD-ROM you submit. If EPA cannot read your comment due to 
technical difficulties and cannot contact you for clarification, EPA 
may not be able to consider your comment. Electronic files should avoid 
the use of special characters, any form of encryption, and be free of 
any defects or viruses. For additional instructions on submitting 
comments, go to Section I of

[[Page 29696]]

the SUPPLEMENTARY INFORMATION section of this document.
    Docket: All documents in the docket are listed in the https://www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available either electronically 
in https://www.regulations.gov or in hard copy at the U.S. Environmental 
Protection Agency, Region 5, Air and Radiation Division, 77 West 
Jackson Boulevard, Chicago, Illinois 60604. This facility is open from 
8:30 a.m. to 4:30 p.m., Monday through Friday, excluding Federal 
holidays. We recommend that you telephone John Summerhays, 
Environmental Scientist, at (312) 886-6067 before visiting the Region 5 
office.

FOR FURTHER INFORMATION CONTACT: John Summerhays, Environmental 
Scientist, Attainment Planning and Maintenance Section, Air Programs 
Branch (AR-18J), U.S. Environmental Protection Agency, Region 5, 77 
West Jackson Boulevard, Chicago, Illinois 60604, (312) 886-6067, 
summerhays.john@epa.gov.

SUPPLEMENTARY INFORMATION: This supplementary information section is 
arranged as follows:

I. What should I consider as I prepare my comments for EPA?
II. What actions is EPA proposing to take?
III. What is the background for this action?
IV. What are the criteria for redesignation to attainment?
V. What is EPA's analysis of the State's request?
    1. Attainment
    2. Fully Approved SIP Meeting All Pertinent Requirements
    a. General Requirements
    b. Section 110(a) Requirements
    c. Emission Inventories
    d. Other Nonattainment Area Requirements
    3. Permanent and Enforceable Emission Reductions
    4. Maintenance Plan
    5. Motor Vehicle Emission Budgets
    6. Summary of Proposed Actions
VI. What are the effects of EPA's proposed actions?
VII. Statutory and Executive Order Reviews

I. What should I consider as I prepare my comments for EPA?

    When submitting comments, remember to:
    1. Identify the rulemaking by docket number and other identifying 
information (subject heading, Federal Register date, and page number).
    2. Follow directions--The EPA may ask you to respond to specific 
questions or organize comments by referencing a Code of Federal 
Regulations (CFR) part or section number.
    3. Explain why you agree or disagree; suggest alternatives and 
substitute language for your requested changes.
    4. Describe any assumptions and provide any technical information 
and/or data that you used.
    5. If you estimate potential costs or burdens, explain how you 
arrived at your estimate in sufficient detail to allow for it to be 
reproduced.
    6. Provide specific examples to illustrate your concerns, and 
suggest alternatives.
    7. Explain your views as clearly as possible, avoiding the use of 
profanity or personal threats.
    8. Make sure to submit your comments by the comment period deadline 
identified.

II. What actions is EPA proposing to take?

    On November 27, 2009, at 74 FR 62243, EPA made a final 
determination that the Evansville area has attained the 1997 annual 
PM2.5 national ambient air quality standards (NAAQS). EPA 
here is proposing to determine that the area continues to attain that 
standard. EPA is also proposing to take several additional actions 
related to Indiana's request to redesignate the area to attainment for 
the 1997 annual PM2.5 NAAQS.
    First, EPA is proposing to approve Indiana's 1997 annual 
PM2.5 maintenance plan for the Evansville area as a revision 
to the Indiana SIP, subject to the proviso that EPA promulgates a final 
Transport Rule requiring power plant emission reductions substantially 
equivalent for purposes of maintaining the PM2.5 standard in 
Evansville to those proposed in EPA's Transport Rule proposal. Since 
maintenance of the standard in Evansville is based in large part on 
maintaining substantial control of power plant emissions, promulgation 
of such a Transport Rule is necessary to help make recent reductions in 
power plant emissions (or equivalent reductions at other power plants) 
permanent and enforceable.
    Second, EPA is proposing to approve the 2005 emission inventory in 
Indiana's maintenance plan as satisfying the requirement of section 
172(c)(3) for a comprehensive emission inventory.
    Third, EPA is proposing to find that, subject to final approval of 
the emissions inventory and the proviso set forth above with respect to 
EPA's proposed Transport Rule, Indiana meets the requirements for 
redesignation of the Evansville area to attainment of the 1997 
PM2.5 NAAQS under section 107(d)(3)(E) of the Clean Air Act. 
Because CAIR was remanded, the reductions associated with that rule 
cannot be considered permanent and enforceable. For this reason, the 
submissions from Indiana do not currently demonstrate satisfaction of 
the requirement of section 107(d)(3)(E)(iii), that the area's air 
quality improvement be due to permanent and enforceable measures. 
However, EPA proposes that this requirement will be met if and when EPA 
finalizes a Transport Rule which, for purposes of this action, is 
substantially equivalent to the Transport Rule that EPA proposed on 
August 2, 2010. Therefore, subject to this proviso, EPA is proposing to 
approve the request from the State of Indiana to change the designation 
of the Evansville area, consisting of Dubois, Vanderburgh, and Warrick 
Counties along with Montgomery Township in Gibson County, Ohio Township 
in Spencer County, and Washington Township in Pike County, from 
nonattainment to attainment of the 1997 PM2.5 NAAQS.
    Finally, EPA is proposing to approve the 2015 and 2022 motor 
vehicle emission budgets (MVEBs) for the Evansville area into the 
Indiana SIP. EPA proposes to take final action on this and the other 
proposed actions delineated in this section if and when EPA takes final 
action promulgating a Transport Rule substantially equivalent for 
purposes of air quality in the Evansville area to the Transport Rule 
proposed on August 2, 2010.

III. What is the background for these actions?

    The first air quality standards for PM2.5 were 
promulgated on July 18, 1997, at 62 FR 38652. EPA promulgated an annual 
standard at a level of 15 micrograms per cubic meter ([mu]g/m\3\), 
based on a three-year average of annual mean PM2.5 
concentrations. In the same rulemaking, EPA promulgated a 24-hour 
standard of 65 [mu]g/m\3\, based on a three-year average of the 98th 
percentile of 24-hour concentrations. On October 17, 2006, at 71 FR 
61144, EPA retained the annual average standard at 15 [mu]g/m\3\ but 
revised the 24-hour standard to 35 [mu]g/m\3\, based again on the 
three-year average of the 98th percentile of 24-hour concentrations.
    On January 5, 2005, at 70 FR 944, as supplemented on April 14, 
2005, at 70 FR 19844, EPA designated the Evansville area as 
nonattainment for the 1997 PM2.5 air quality standards. In 
that action, EPA defined the Evansville nonattainment area to include 
the entirety of Dubois, Vanderburgh, and Warrick Counties and portions 
of three other counties, specifically including

[[Page 29697]]

Montgomery Township in Gibson County, Ohio Township in Spencer County, 
and Washington Township in Pike County. On November 13, 2009, at 74 FR 
58688, EPA promulgated designations for the 24-hour standard set in 
2006, designating the Evansville area as attaining this standard. In 
that action, EPA also clarified the designations for the NAAQS 
promulgated in 1997, stating that the Evansville area remained 
designated nonattainment for the 1997 annual PM2.5 standard, 
but was designated attainment for the 1997 24-hour standard. Thus 
today's action does not address attainment of either the 1997 or the 
2006 24-hour standards.
    In response to legal challenges of the annual standard promulgated 
in 2006, the D.C. Circuit remanded this standard to EPA for further 
consideration. See American Farm Bureau Federation and National Pork 
Producers Council, et al. v. EPA, 559 F.3d 512 (D.C. Cir. 2009). 
However, given that the 1997 and 2006 annual standards are essentially 
identical, attainment of the 1997 annual standard would also indicate 
attainment of the remanded 2006 annual standard. Since the Evansville 
area is designated nonattainment only for the annual standard 
promulgated in 1997, today's action addresses redesignation to 
attainment only for this standard.
    Indiana has provided multiple submittals in support of its request 
for redesignation of the Evansville area. On April 3, 2008, Indiana 
submitted its original request that EPA redesignate the Evansville area 
to attainment of the 1997 annual PM2.5 standard. This 
request was based on 2004 to 2006 monitoring data indicating that no 
monitor violated the annual standard. A public hearing was held on 
March 27, 2008, and the comment period closed on March 31, 2008. 
Indiana completed the redesignation request by submitting documentation 
of the public hearing conducted by the State for the PM2.5 
redesignation request and additional regional air quality analysis on 
October 20, 2008. On March 6, 2009, Indiana provided updated monitoring 
data for the 2006 to 2008 period. On April 7, 2009, Indiana submitted 
supplemental information on regional emissions. On December 7, 2009, 
Indiana submitted modeling intended to show that the Evansville area 
would attain and maintain the standard even in the absence of the 
emission reductions prompted by CAIR. On January 28, 2011, Indiana 
submitted updated emissions data (including updated MVEBs) to show that 
maintenance extended further into the future, to 2022. On April 8, 
2011, Indiana resubmitted the information submitted on January 28, 
2011, in conjunction with evidence that the State provided a public 
comment period and held a public hearing on the information and 
received no public comments.
    Fine particle pollution can be emitted directly or formed 
secondarily through chemical reactions in the atmosphere. Sulfates are 
a type of secondary particle formed from sulfur dioxide 
(SO2) emissions from power plants and industrial facilities. 
Nitrates, another common type of secondary particle, are formed from 
emissions of nitrogen oxides (NOX) from power plants, 
automobiles, and other combustion sources.
    Given the significance of sulfates and nitrates in the Evansville 
area, the area's air quality is strongly affected by regulations of 
SO2 and NOX emissions from power plants. EPA 
proposed CAIR on January 30, 2004, at 69 FR 4566, promulgated CAIR on 
May 12, 2005, at 70 FR 25162, and promulgated associated federal 
implementation plans (FIPs) on April 28, 2006, at 71 FR 25328, in order 
to reduce SO2 and NOX emissions and improve air 
quality in many areas across the eastern part of the United States. 
However, on July 11, 2008, the D.C. Circuit Court of Appeals issued a 
decision to vacate and remand both CAIR and the associated CAIR FIPs in 
their entirety (North Carolina v. EPA, 531 F.3d 836 (D.C. Cir. 2008)). 
EPA petitioned for rehearing, and the court issued an order remanding 
CAIR and the CAIR FIPs to EPA without vacatur (North Carolina v. EPA, 
550 F.3d 1176 (D.C. Cir. 2008)). The Court, thereby, left CAIR in place 
in order to ``temporarily preserve the environmental values covered by 
CAIR'' until EPA replaces it with a rule consistent with the court's 
opinion. Id. at 1178. The court directed EPA to ``remedy CAIR's flaws'' 
consistent with its July 11, 2008, opinion, but declined to impose a 
schedule on EPA for completing that action. Id. As a result of these 
court rulings, the power plant emission reductions that have resulted 
from the development, promulgation, and implementation of CAIR, and the 
associated air quality improvement that has occurred in the Evansville 
area and elsewhere, cannot be considered permanent.
    On August 2, 2010, EPA published its proposal of the Transport Rule 
to address interstate transport of emissions with respect to the 1997 
ozone and the 1997 and 2006 PM2.5 NAAQS, to replace CAIR. 
(See 75 FR 45210.) This rule, as proposed, would require substantial 
reductions of SO2 and NOX emissions from electric 
generating units (EGUs) across most of the Eastern United States. In 
particular, it would require reductions of these emissions to levels 
well below the levels that led to attainment in the Evansville area. 
The proposed Transport Rule proposed to establish permanent and 
enforceable limits on EGU emissions across most of the Eastern United 
States. Since the Transport Rule as proposed would require EGU 
emissions to be well below the levels that have led to attainment in 
the Evansville area. If EPA finalizes a Transport Rule that similarly 
requires EGU emissions to be below the levels that led to attainment in 
the Evansville area, that rule would provide support for a 
determination that the air quality improvement may be considered 
permanent and enforceable.

IV. What are the criteria for redesignation to attainment?

    The Clean Air Act sets forth the requirements for redesignating a 
nonattainment area to attainment. Specifically, section 107(d)(3)(E) of 
the Clean Air Act allows for redesignation provided that: (1) The 
Administrator determines that the area has attained the applicable 
NAAQS based on current air quality data; (2) the Administrator has 
fully approved an applicable state implementation plan for the area 
under section 110(k) of the Clean Air Act; (3) the Administrator 
determines that the improvement in air quality is due to permanent and 
enforceable emission reductions resulting from implementation of the 
applicable SIP, Federal air pollution control regulations, and other 
permanent and enforceable emission reductions; (4) the Administrator 
has fully approved a maintenance plan for the area meeting the 
requirements of section 175A of the Clean Air Act; and (5) the state 
containing the area has met all requirements applicable to the area for 
purposes of redesignation under section 110 and part D of the Clean Air 
Act.

V. What is EPA's analysis of the State's request?

    EPA is proposing to approve the redesignation of the Evansville 
area to attainment of the 1997 annual PM2.5 NAAQS and is 
proposing to approve the maintenance plan for the area and other 
related SIP revisions, subject to the provisos discussed in this 
notice. The bases for these proposed actions follow.

1. Attainment

    As noted above, in a final rulemaking dated November 27, 2009, at 
74 FR 62243, EPA determined that the Evansville area is attaining the 
1997 annual PM2.5 NAAQS. Further

[[Page 29698]]

discussion of pertinent air quality issues underlying this 
determination was provided in the notice of proposed rulemaking, 
published on September 24, 2009, at 74 FR 49690. This determination was 
based primarily on air quality data from 2006 to 2008.
    EPA has reviewed more recent data, including certified, quality-
assured data for 2009 and data for all of 2010. These data show that 
the Evansville area continues to attain the 1997 annual 
PM2.5 NAAQS. Table 1 provides an historical summary of air 
quality data for the area. This summary is based on quality assured 
data that have been entered into the EPA Air Quality System, though the 
data for 2010 have not yet been certified.

                             Table 1--PM2.5 Design Values for Evansville Area Sites
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              County                    Site name         Site No.    2004-2006  2006-2008  2007-2009  2008-2010
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Dubois (ended 2008)..............  Jasper Sport.......     180370004      *13.6      *13.4      *13.4  .........
Dubois (ended 2008)..............  Jasper Golf........     180370005      *13.7       13.7      *13.7  .........
Dubois...........................  6th Street.........     180372001       15.0       13.6      *13.3       12.1
Gibson (began 2009)..............  Oakland City.......     180510012  .........  .........  .........       12.2
Spencer..........................  Dale...............     181470009       13.9       13.0       12.6       13.0
Vanderburgh (ended 2009).........  Civic Center.......     181630006       14.5       13.4      *12.8  .........
Vanderburgh......................  West Mill Road.....     181630012       14.6       13.7      *13.0  .........
Vanderburgh......................  U. of Evansville...     181630016       14.8       13.6       13.1       12.8
Vanderburgh......................  Post Office........     181630020  .........  .........  .........      *12.9
Vanderburgh......................  Buena Vista........     181630021  .........  .........  .........      *13.0
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* Less than 75 percent complete data in at least one quarter.

    Several of these sites had less than 75 percent complete data for 
one or more of the applicable recent quarters. From 2008 to 2009, four 
monitoring sites ended operation, and three new sites began operating. 
In its prior determination of attainment, EPA determined that prior to 
ending operation, these monitoring sites recorded data indicating 
attainment of the annual PM2.5 standard.
    From 2008 to 2009, three additional sites began operating: Site 18-
051-0012 in Gibson County starting in 2008, and sites 18-163-0020 and 
18-163-0021 in Vanderburgh County starting in 2009. As a result of 
their short operating history, these monitors have incomplete data for 
purposes of comparison to the NAAQS, but the data that are available, 
summarized in Table 1 above, indicate concentrations well below the 
NAAQS, consistent with other data showing continued attainment in the 
area.
    Although the monitoring network was in flux during this latter 
period, the area has been and continues to be monitored at numerous 
locations addressing the range of locations in the area with potential 
to violate the standard. EPA has approved these various revisions to 
Indiana's monitoring network, including approval most recently on 
October 29, 2010, reflecting its belief that the revised network 
remains adequate to assess air quality in the Evansville area.
    For this and related reasons, EPA proposes to approve the use of 
these incomplete data, pursuant to Subpart 4.1(c) of 40 CFR part 50, 
Appendix N, as supplemental evidence for evaluating whether the 
Evansville area is attaining the standard.
    Indiana's request to redesignate the Evansville area was predicated 
on monitoring data from 2004 to 2006 showing that the area meets the 
1997 PM2.5 NAAQS. Subsequently, EPA determined that the area 
is meeting the 1997 PM2.5 NAAQS, based primarily on 2006 to 
2008 data. According to more recent data, average concentrations for 
all sites, including these sites with incomplete data as well as the 
sites with complete data, remain well below the PM2.5 NAAQS. 
Indeed, EPA believes that the Evansville area has been attaining the 
PM2.5 NAAQS for five consecutive three-year periods. 
Therefore, EPA proposes to determine that the Evansville area continues 
to meet the 1997 annual PM2.5 NAAQS.

2. Fully Approved SIP Meeting All Pertinent Requirements

a. General Requirements
    Sections 107(d)(3)(E)(ii) and 107(d)(3)(E)(v) set forth related 
requirements for the State to have a fully approved SIP meeting all 
pertinent requirements, and the following discussion addresses 
Indiana's satisfaction of both of these portions of section 
107(d)(3)(E). Since the passage of the Clean Air Act in 1970, Indiana 
has adopted and submitted, and EPA has fully approved, provisions 
addressing the various required SIP elements addressing particulate 
matter in the Evansville area and elsewhere in Indiana. Indiana 
submitted the ``State of Indiana Air Pollution Control Implementation 
Plan,'' its SIP, on January 31, 1972. EPA approved Indiana's SIP on May 
31, 1972, at 37 FR 10863. These rules addressed total suspended 
particulate (TSP), reflecting the particulate size range regulated 
under the 1971 standards. EPA designated Evansville as nonattainment 
for TSP on March 3, 1978, at 43 FR 8962. Indiana submitted general TSP 
Reasonably Available Control Technology emission limits and regulations 
for process sources on October 6, 1980. On January 29, 1981, Indiana 
submitted its source specific limits for Vanderburgh County with 
amendments on October 28, 1981. These elements were approved into the 
Indiana SIP on July 16, 1982. On July 1, 1987, EPA replaced the TSP 
standard with a standard for finer-sized particulate matter, 
specifically for particles up to a nominal aerodynamic diameter of ten 
micrometers, a set of particles known as PM10. EPA 
promulgated designations under the PM10 NAAQS on March 15, 
1991, at 56 FR 11101. The Evansville area was designated as attaining 
the PM10 standards. Consequently, Indiana had no obligation 
to submit PM10 attainment plans for the Evansville area.
b. Section 110(a) Requirements
    EPA believes that the section 110 elements not connected with 
nonattainment plan submissions and not linked to the area's 
nonattainment status are not applicable requirements for purposes of 
review of the State's redesignation request.
    On December 7, 2007, September 19, 2008, and October 20, 2009, 
Indiana made submittals addressing ``infrastructure SIP'' elements 
required under Clean Air Act section 110(a)(2). EPA has published 
proposed rulemaking on these submittals

[[Page 29699]]

(published on April 28, 2011, at 76 FR 23757), but has not completed 
final rulemaking on these submittals. However, the requirements of 
section 110(a)(2) are statewide requirements that are not linked to the 
PM2.5 nonattainment status of or requirements for the 
Evansville area. EPA believes that section 110 elements not linked to 
an area's nonattainment status are not applicable for purposes of 
redesignation. See the Reading, Pennsylvania proposed and final 
rulemakings (October 10, 1996, at 61 FR 53174-53176, and May 7, 1997, 
at 62 FR 24826), the Cleveland-Akron-Loraine, Ohio final rulemaking 
(May 7, 1996, at 61 FR 20458), and the Tampa, Florida final rulemaking 
(December 7, 1995, at 60 FR 62748). Therefore, notwithstanding the fact 
that EPA has not yet completed rulemaking on Indiana's submittals for 
the ``infrastructure SIP'' elements of section 110(a)(2), EPA believes 
that these elements are not applicable requirements for purposes of 
review of the State's redesignation request.
c. Emission Inventories
    Under section 172(c)(3), Indiana is required to submit a 
comprehensive, accurate and current inventory of actual emissions. As 
part of Indiana's redesignation request for the Evansville area, the 
State submitted a maintenance plan that included emissions inventories 
for the area for SO2 and NOX (which are 
precursors for secondarily formed PM2.5) and for directly 
emitted PM2.5 for 2005, 2015, 2020, and 2022. The 
inventories for 2005 address the requirement under section 172(c)(3) 
for a base year emission inventory, and the other inventories help 
address the requirement for a demonstration that the area can expect to 
maintain the standard for at least 10 years after approval of a 
redesignation.
    For each of the applicable pollutants and years, Indiana prepared 
emission estimates by county and by five source types, namely onroad 
mobile sources, nonroad mobile sources, area sources, EGUs, and other 
point sources. Onroad and nonroad mobile source emissions were 
estimated by the Evansville Metropolitan Planning Organization and by 
the Indiana Department of Transportation. The onroad emission estimates 
were derived using EPA's MOBILE6.2 emission model. When Indiana 
submitted updated emissions data on April 8, 2011, which showed that 
the area continued to maintain the annual PM2.5 standard to 
2022, it continued to use MOBILE6.2 rather than MOVES2010a to estimate 
the onroad emissions.\1\ EPA is proposing to approve Indiana's 
continued use of MOBILE6.2 in this maintenance plan. Air quality data 
indicates that the area has attained the annual PM2.5 standard and 
large emissions reductions are expected in the coming years, which will 
allow the area to continue to meet the annual PM2.5 standard. If 
MOVES2010a had been used to estimate onroad emissions for the new last 
year of this maintenance plan, it would not change this conclusion. In 
addition, the recent submittal only extended the maintenance period by 
two years and it was not necessary for the submittal to revisit earlier 
years of the maintenance period. This extension was necessary because 
EPA could not act on the submittal at an earlier date due to issues 
related to the remand of the CAIR rule and the Clean Air Act's 
requirement that maintenance plans address a period that covers 10 
years after EPA approves the submitted maintenance plan. Also, 
consistent with Question 5 in EPA's ``Policy Guidance on the Use of 
MOVES 2010 for State Implementation Plan Development, Transportation 
Conformity, and Other Purposes'' (https://www.epa.gov/otaq/models/moves/420b09046.pdf) we believe that since the bulk of the work on the 
maintenance plan was performed in 2008, which well before MOVES2010 was 
released, the continued use of MOBILE6.2 in this maintenance plan is 
warranted. Even the supplemental work performed by Indiana to support 
the April 2011 revision was done relatively soon after MOVES was 
officially released for use in SIPs on March 2, 2010, at 75 FR 9411. It 
is also worth noting that the area has been attaining the standard for 
several years, and future anticipated emissions reductions will ensure 
that the area will continue to maintain the standard through the 
maintenance period. Based on all of these factors we believe that 
Indiana's continued use of MOBILE6.2 is justified because it avoids an 
adverse impact on state resources as is also described in Question 5 of 
the MOVES SIP and Conformity guidance document.
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    \1\ MOVES2010a is EPA's most recent model for estimating on-road 
mobile source emissions. It was officially released for use in SIPs 
and regional transportation conformity determinations on March 2, 
2010, at 75 FR 9411.
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    Most of the nonroad emission estimates were derived using EPA's 
NONROAD model. Nonroad activity levels reflect information compiled by 
the Lake Michigan Air Directors Consortium (LADCO), described at https://www.ladco.org/reports/technical_support_document/references/round_5_emissions_summary-february_2008.pdf. In addition, the inventory 
includes emission estimates for marine and railroad sources under 
contract to LADCO. Area source emissions were developed using local 
activity level estimates and EPA emission factors as reflected in the 
2005 National Emissions Inventory.
    Base year emissions for EGUs for SO2 and NOX 
were obtained from continuously monitored emission data that the 
facilities reported to EPA's Clean Air Markets Division. Projections of 
these emissions were based on simulations using the Integrated Planning 
Model (IPM) premised on implementation of CAIR and the associated 
allowance allocations and trading programs. Indiana's April 2011 
submittal states that these emission projections rely on an expectation 
that the Transport Rule that EPA proposed on August 2, 2010, will 
require EGUs to achieve a similar set of reductions as has been 
required by CAIR. EGU emissions of PM2.5 were estimated 
using the same information on activity levels (i.e., baseline heat 
inputs reported to EPA and projected heat inputs forecast by IPM) in 
conjunction with EPA emission factors and current emission control 
levels. For other point sources, baseline emissions were obtained from 
routine source reports to the State, and projections were based on 
growth factors developed by LADCO based on appropriate economic 
indicators.
    Table 2 summarizes the 2005 base year emissions estimates, 
subdivided by source type, that Indiana provided in its maintenance 
plan as submitted on January 28, 2011. The area has a modest number of 
people--the 2009 population estimate for the Evansville Metropolitan 
Statistical Area according to the U.S. Census Bureau is 351,911. The 
PM2.5 nonattainment area includes several large power plants 
that serve a broad area within the industrial Midwest and beyond. 
Therefore, point sources (in particular power plants) emit a very high 
fraction of the area's emissions. Indeed, point sources are estimated 
to emit over 99 percent of the area's SO2 emissions, about 
86 percent of the area's NOX emissions, and about 71 percent 
of the area's PM2.5 emissions, and most of the point source 
emissions are from power plants. EPA proposes to find that

[[Page 29700]]

the inventory satisfies the requirements of section 172(c)(3).

 Table 2--Summary of 2005 Emissions Estimates for the Evansville Area by
                               Source Type
                             [Tons per year]
------------------------------------------------------------------------
                                          SO2         NOX        PM2.5
------------------------------------------------------------------------
EGUs................................     360,822      85,320       8,240
Point...............................       3,685         774       1,427
On-road.............................         237       6,528         118
Non-road............................         537       5,676         337
Area................................         674       1,624          37
                                     -----------------------------------
    Total...........................     365,954      99,922      10,160
------------------------------------------------------------------------

    Table 3 shows the 2005 base year emission estimates and the 2015 
and 2022 emission projections for the Evansville area that Indiana 
provided in its April 8, 2011, submission.

                                  Table 3--Evansville Area Emission Projections
                                                 [Ions per year]
----------------------------------------------------------------------------------------------------------------
                                             SO2                        NOX                       PM2.5
----------------------------------------------------------------------------------------------------------------
2005............................  365,954..................  99,922...................  10,160.
2015............................  117,830..................  59,897...................  13,892.
2022............................  94,627...................  51,885...................  12,604.
Change 2005-2022................  -271,327.................  -48,037..................  +2,444.
                                  74% decrease.............  48% decrease.............  24% increase.
----------------------------------------------------------------------------------------------------------------

c. Other Nonattainment Area Requirements
    EPA is proposing to determine that, if EPA issues final approval of 
the emission inventories discussed above, the Indiana SIP will meet the 
SIP requirements for the Evansville area applicable for purposes of 
redesignation under Part D of the Clean Air Act. Subpart 1 of Part D, 
sections 172 to 176 of the Clean Air Act, set forth the basic 
nonattainment plan requirements applicable to PM2.5 
nonattainment areas.
    Under section 172, states with nonattainment areas must submit 
plans providing for timely attainment and meeting a variety of other 
requirements. However, pursuant to 40 CFR 51.1004(c), EPA's November 
27, 2009, determination that the Evansville area is attaining the 
PM2.5 standard suspended Indiana's obligation to submit most 
of the attainment planning requirements that would otherwise apply. 
Specifically, the determination of attainment suspended Indiana's 
obligation to submit an attainment demonstration, and requirements to 
provide for reasonable further progress, reasonable available control 
measures, and contingency measures under section 172(c)(9).
    The General Preamble for Implementation of Title I (57 FR 13498, 
April 16, 1992) also discusses the evaluation of these requirements in 
the context of EPA's consideration of a redesignation request. The 
General Preamble sets forth EPA's view of applicable requirements for 
purposes of evaluating redesignation requests when an area is attaining 
the standard. General Preamble for Implementation of Title I (57 FR 
13498, April 16, 1992).
    Because attainment has been reached, no additional measures are 
needed to provide for attainment, and section 172(c)(1) requirements 
for an attainment demonstration and RACM are no longer considered to be 
applicable for purposes of redesignation as long as the area continues 
to attain the standard until redesignation. See also 40 CFR 51.1004(c). 
The RFP requirement under section 172(c)(2) and contingency measures 
requirement under section 172(c)(9) are similarly not relevant for 
purposes of redesignation.
    Section 172(c)(3) requires submission and approval of a 
comprehensive, accurate and current inventory of actual emissions. As 
part of Indiana's redesignation request for the Evansville area, the 
State submitted a 2005 emissions inventory. As discussed above, EPA is 
proposing to approve this inventory as meeting the section 172(c)(3) 
emissions inventory requirement.
    Section 172(c)(4) requires the identification and quantification of 
allowable emissions for major new and modified stationary sources in an 
area, and section 172(c)(5) requires source permits for the 
construction and operation of new and modified major stationary sources 
anywhere in the nonattainment area. EPA has determined that, since 
prevention of significant deterioration (PSD) requirements will apply 
after redesignation, areas being redesignated need not comply with the 
requirement that a nonattainment new source review (NSR) program be 
approved prior to redesignation, provided that the area demonstrates 
maintenance of the NAAQS without part D NSR. A more detailed rationale 
for this view is described in a memorandum from Mary Nichols, Assistant 
Administrator for Air and Radiation, dated October 14, 1994, entitled, 
``Part D New Source Review Requirements for Areas Requesting 
Redesignation to Attainment.'' Indiana has demonstrated that emissions 
will remain sufficiently low even without part D NSR in effect for the 
Evansville area to be able to maintain the standard; therefore, the 
State need not have a fully approved part D NSR program prior to 
approval of the redesignation request. The State's PSD program will 
become effective in the Evansville area upon redesignation to 
attainment. See rulemakings for Detroit, Michigan (March 7, 1995, at 60 
FR 12467-12468); Cleveland-Akron-Lorain, Ohio (May 7,

[[Page 29701]]

1996, at 61 FR 20458, 20469-20470); Louisville, Kentucky (October 23, 
2001, at 66 FR 53665); and Grand Rapids, Michigan (June 21, 1996, at 61 
FR 31834-31837).
    Section 172(c)(6) requires the SIP to contain control measures 
necessary to provide for attainment of the standard. Because attainment 
has been reached, no additional measures are needed to provide for 
attainment.
    Section 172(c)(7) requires the SIP to meet the applicable 
provisions of section 110(a)(2). As noted above, we believe the Indiana 
SIP meets the requirements of section 110(a)(2) applicable for purposes 
of redesignation.
    Section 176(c) of the CAA requires states to establish criteria and 
procedures to ensure that Federally-supported or funded activities, 
including highway projects, conform to the air quality planning goals 
in the applicable SIPs.
    EPA believes that it is reasonable to interpret the conformity SIP 
requirements as not applying for purposes of evaluating the 
redesignation request under section 107(d) for two reasons. First, the 
requirement to submit SIP revisions to comply with the conformity 
provisions of the CLEAN AIR ACT continues to apply to areas after 
redesignation to attainment, since such areas would be subject to a 
section 175A maintenance plan. Second, EPA's Federal conformity rules 
require the performance of conformity analyses in the absence of 
Federally-approved state rules. Therefore, because areas are subject to 
the conformity requirements regardless of whether they are redesignated 
to attainment and, because they must implement conformity under Federal 
rules if state rules are not yet approved, EPA believes it is 
reasonable to view these requirements as not applying for purposes of 
evaluating a redesignation request. See Wall v. EPA, 265 F.3d 426 (6th 
Cir. 2001), upholding this interpretation. See also 60 FR 62748, 62749-
62750 (Dec. 7, 1995) (Tampa, Florida).
    EPA approved Indiana's general and transportation conformity SIPs 
on January 14, 1998, at 63 FR 2146, and August 17, 2010, at 75 FR 
50730, respectively. Indiana has submitted onroad motor vehicle budgets 
for the Evansville area for 2015 and 2022. The area must use the MVEBs 
from the maintenance plan in any conformity determination that is 
effective on or after the effective date of the maintenance plan 
approval.
    No SIP provisions relevant to the Evansville area are currently 
disapproved, conditionally approved, or partially approved. If EPA 
approves the Evansville area emission inventory as proposed, EPA 
believes that Indiana will have a fully approved SIP for all 
requirements applicable for purposes of redesignation.

3. Permanent and Enforceable Emission Reductions

    Indiana's original redesignation submission cited a number of 
regulatory programs that it believed resulted in the air quality 
improvement in the Evansville area between the period that was the 
basis of the area's 1997 PM2.5 nonattainment designation 
(2002 to 2004), and the period that the Evansville area began attaining 
the 1997 annual PM2.5 standard (2004 to 2006). These 
programs included the EPA NOX Budget Trading Program, the 
acid rain program, mobile source rules such as Heavy-duty Highway 
Vehicle standards and Non-road Diesel Engine standards, and CAIR.
    Indiana subsequently supplemented its request with submittals 
intended to demonstrate that the Evansville area could be expected to 
continue to attain the standard even if the emission reductions 
associated with the promulgation of CAIR did not continue. In 
particular, on December 7, 2009, Indiana submitted the results of 
modeling purporting to show PM2.5 concentrations that 
Indiana estimated would occur in the Evansville area in the absence of 
CAIR. For most power plants, this modeling was based on projections 
derived from actual emission rates for 2007. For the power plants 
within the Evansville nonattainment area, this modeling used the 
highest emission rates from 2000 to 2007. Indiana's modeling showed 
that these emission rates yielded Evansville area concentrations below 
the PM2.5 NAAQS.
    EPA has reviewed Indiana's submission and believes that Indiana's 
modeling does not properly reflect power plant emissions that would 
occur in the absence of CAIR. Although the compliance deadlines in CAIR 
were 2009 for the first phase of NOX reductions and 2010 for 
the first phase of SO2 reductions, CAIR provided significant 
incentives for earlier emission reductions. Indeed, especially for 
SO2, a comparison of 2007 emissions for states in the CAIR 
region against 2003 emissions shows a significant decline in emissions. 
For example, according to continuous emission monitoring data submitted 
by EGUs to EPA's Clean Air Markets Division, EGU emissions of 
SO2 in Indiana declined from 804,800 tons per year in 2003 
to 714,500 tons per year in 2007, a decline of 93,000 tons per year. 
Similarly, according to the same set of data, EGU emissions of 
NOX in Indiana declined from 261,000 tons per year to 
196,600 tons per year, a decline of 64,400 tons per year. Similar 
declines occur in other states influencing Evansville area air quality. 
These declines can reasonably be attributed to the incentives of CAIR, 
such that even the 2004 to 2006 air quality data underlying Indiana's 
request would reflect benefits from EPA's development, proposal, and 
promulgation of CAIR.
    Given that the DC Circuit has now remanded CAIR to EPA, it will not 
remain in force indefinitely. As a consequence, the emission reductions 
associated with CAIR cannot be considered to be permanent.
    EPA's proposed Transport Rule would, in a manner consistent with 
the D.C. Circuit opinion on CAIR, among other things identify emission 
reductions in the Eastern United States necessary to address 
significant interference with attainment and maintenance pursuant to 
section 110(a)(2)(d)(i)(I) of the Clean Air Act with respect to the 
1997 ozone and 1997 and 2006 PM2.5 NAAQS. The comment period 
on this proposed rule closed on October 1, 2010. EPA is reviewing all 
comments received. EPA may not prejudge the requirements of the final 
Transport Rule, and so cannot complete final rulemaking on Indiana's 
redesignation request in a manner that relies on Transport Rule 
requirements unless and until EPA has promulgated a final Transport 
Rule.
    In the proposed Transport Rule, EPA proposed to quantify the 
reductions needed in specific states to address each covered state's 
significant contribution to nonattainment and interference with 
maintenance of specific NAAQS. In that action, EPA also proposed to 
establish FIPs to ensure that the significant contribution to 
nonattainment and interference with maintenance identified by EPA is 
prohibited.
    The Evansville area is notable for having several sizable electric 
generating facilities, and most of these facilities are operating with 
new or upgraded SO2 and NOX controls for their 
coal-fired units. Vectron's A.B. Brown facility operates a dual alkali 
system for SO2 control and select catalytic reduction (SCR) 
of NOX. Alcoa's Warrick Power Plant uses wet lime scrubbing 
to control SO2 emissions and combustion controls, and uses 
SCR for one unit and low NOX burners (LNB) and over-fire air 
(OFA) for all units to limit its NOX emissions. Vectron's 
F.B. Culley generating station uses wet limestone scrubbing for 
SO2 control and SCR with LNB for NOX control at 
its two

[[Page 29702]]

units. Hoosier Energy uses LNB to reduce NOX emissions from 
both Frank E. Ratts Generating Station units. Duke Energy's Gibson 
plant uses wet limestone scrubbing with SCR, LNB, and OFA on all five 
units. Indianapolis Power and Light operates wet limestone scrubbers 
along with SCR, LNB, and OFA on the four units of its Petersburg power 
plant. Indiana-Michigan Power uses LNB on the two coal-fired units at 
the Rockport plant.
    These emission controls, along with similar controls at many other 
plants in the Eastern United States, are providing substantial air 
quality benefits. As explained above, some of the reductions were 
associated with the now-remanded CAIR. The proposed Transport Rule, if 
finalized, would similarly require reductions in NOX and 
SO2 from EGUs. The reductions associated with the Transport 
Rule, if and when it is finalized, may be considered permanent and 
enforceable.
    The modeling for the proposed Transport Rule identified 13 states, 
including Indiana, that have emissions that significantly affect 
Evansville area air quality. Table 4 shows state-wide emission 
estimates for SO2 and NOX for 2005, 2012, and 
2014 for these states. The values for 2005 reflect base year emissions 
estimates. Given the timing of attainment in the Evansville area, these 
values reflect an approximation of statewide emission levels at which 
the Evansville area attained the PM2.5 standard. The values 
for 2012 reflect estimates for a scenario in which neither CAIR nor a 
replacement Transport Rule is in effect, reflecting a baseline that EPA 
used in developing its proposed rule. The values for 2014 reflect 
estimates for a scenario in which the proposed Transport Rule is 
finalized as proposed. These estimates are taken from Tables 6-1 
(NOX) and 6-2 (SO2) of the emissions technical 
support document for the proposed Transport Rule, available at https://www.epa.gov/airquality/transport/pdfs/TR_Proposal_Emissions_TSD.pdf. 
These estimates exclude emissions from fires, which are a small 
fraction of the inventory (well under 0.1 percent) that is projected to 
remain constant and does not materially affect the comparison here.

      Table 4--SO2 and NOX Emissions for States Identified in the Proposed Transport Rule as Significantly
              Contributing to Nonattainment or Interfering With Maintenance in the Evansville Area
                                                 [Tons per year]
----------------------------------------------------------------------------------------------------------------
                                            SO2 emissions                             NOX emissions
                             -----------------------------------------------------------------------------------
            State                             2012 (w/o     2014 (w/                    2012 (w/o     2014 (w/
                                  2005        Transport     Transport       2005        Transport     Transport
                                                Rule)         Rule)                       Rule)         Rule)
----------------------------------------------------------------------------------------------------------------
Indiana.....................     1,047,371       986,601       396,403       614,861       505,039       386,251
Alabama.....................       592,389       461,314       296,138       443,748       360,357       280,763
Georgia.....................       748,020       674,183       214,726       577,858       405,825       337,889
Illinois....................       516,950       866,376       304,834       773,276       542,886       480,743
Iowa........................       221,877       250,930       182,875       312,015       251,632       221,442
Kentucky....................       572,424       780,885       182,630       435,837       345,073       247,270
Michigan....................       490,190       415,042       300,560       638,546       478,625       410,319
Missouri....................       421,979       570,575       315,283       505,195       353,407       317,092
Ohio........................     1,276,270     1,076,470       361,138       816,239       552,864       453,167
Pennsylvania................     1,173,296     1,119,680       303,071       704,936       566,301       454,248
Tennessee...................       388,191       708,905       218,065       471,705       338,154       270,171
West Virginia...............       535,586       645,431       184,341       294,016       206,630       144,970
Wisconsin...................       263,615       181,760       159,927       358,787       257,290       228,637
                             -----------------------------------------------------------------------------------
    Total...................     8,250,163     8,740,164     3,419,991     6,949,024     5,166,095     4,232,962
----------------------------------------------------------------------------------------------------------------

    In Table 4, 2005 emissions represent an approximation of emissions 
at which Evansville attains the standard. Table 4 shows that, in 
comparison, the proposed Transport Rule would establish enforceable 
emission restrictions that would be expected to result in emissions in 
the most pertinent states (as listed in Table 4) that for 
SO2 are 4,830,172 tons per year (59 percent) lower and that 
for NOX are 2,716,062 tons per year (39 percent) lower. That 
is, the proposed Transport Rule would provide for permanent and 
enforceable emission reductions in the Eastern United States that are 
significantly greater than the reductions needed to assure maintenance 
in the Evansville area.
    Similar results are obtained by comparing emission estimates in 
2012 without the proposed Transport Rule to emission estimates in 2014 
with the proposed Transport Rule. In the proposed Transport Rule, EPA 
estimated that total emissions across these states would reflect 
5,320,173 tons per year lower SO2 emissions and 933,133 tons 
per year lower NOX emissions in the 2014 controlled case 
than in the 2012 base case, i.e., emissions that are 61 percent and 18 
percent lower, respectively. According to EPA modeling for the proposed 
Transport Rule, comparing concentrations projected in 2014 with the 
proposed Transport Rule in place against concentrations projected in 
2012 in the absence of a Transport Rule, the Transport Rule achieves 
approximately a 4 [mu]g/m\3\ air quality improvement in the Evansville 
area, yielding concentrations well below the annual PM2.5 
NAAQS and below the concentrations that have been achieved by power 
plant emission reductions to date.
    The modeling for the proposed Transport Rule also projects an 
Evansville area concentration of about 11 [mu]g/m\3\ in 2014 based on 
implementation of the proposed Transport Rule, whereas for purposes of 
this proposed redesignation it is only necessary for the Transport Rule 
to help provide for the Evansville area to maintain a concentration at 
or below 15 [mu]g/m\3\.
    This proposal is premised on the expectation that the final 
Transport Rule will be similarly effective as the proposed Transport 
Rule would be in providing for maintenance of the 1997 PM2.5 
standard in the Evansville area. Given the substantial margin by which 
EPA expects the Evansville area to maintain the standard, numerous 
details

[[Page 29703]]

of the final Transport Rule could differ from corresponding features of 
the proposed Transport Rule without causing changes in the impact on 
Evansville air quality that are significant for purposes of this 
proposal to redesignate the Evansville area. This proposal to 
redesignate the Evansville area is predicated on the final Transport 
Rule being substantially equivalent for purposes of air quality in the 
Evansville area to the Transport Rule proposed on August 2, 2010. In 
EPA's view, this premise will be met if the emission levels expected 
under the final Transport Rule in states most pertinent to Evansville, 
and the associated expected air quality benefits in Evansville, are 
sufficiently similar to the emission levels and associated Evansville 
air quality benefits expected under the proposed rule so as to provide 
a comparable degree of confidence that the Evansville area will 
maintain the standard.
    In summary, a limited set of reductions of EGU emissions of 
SO2 and NOX contributed significantly to the air 
quality improvement in the Evansville area. Given the remanded status 
of CAIR, this air quality improvement cannot be considered permanent. 
However, the proposed Transport Rule proposed to mandate even greater 
reductions than have already occurred and, more importantly, proposed 
to mandate more reductions than are needed to maintain the standard in 
the Evansville area. Therefore, with the final promulgation of a 
Transport Rule that is substantially equivalent to the proposed rule 
for purposes of maintaining the standard in the Evansville area, in 
combination with the other measures cited by Indiana, EPA believes that 
the emission reductions that led the Evansville area to attain the 
PM2.5 air quality standard could be considered as permanent 
and enforceable for purposes of section 107(d)(3)(E)(iii).

4. Maintenance Plan

    Sections 107(d)(3)(E)(iv) and 175A require that the State 
demonstrate that the area to be redesignated will continue to meet the 
PM2.5 NAAQS for at least a ten-year maintenance period after 
redesignation in 2011. Indiana's maintenance plan includes emission 
inventories discussed in section V.2.c above.
    The sizeable reductions in SO2 and NOX 
emissions by 2015 and 2022 shown in Table 3 above are due in 
significant part to restrictions mandated by EPA to reduce power plant 
emissions of SO2 and NOX in the Eastern United 
States in order to reduce pollutant transport in this region. In this 
inventory, Indiana used emission projections premised on the 
implementation of CAIR requirements as an approximation of the 
emissions levels the State projects to occur following the promulgation 
of the Transport Rule. As explained above, the DC Circuit found CAIR 
unlawful and remanded it to EPA. Because CAIR is not in place 
permanently, and because EPA has not completed final promulgation of 
the Transport Rule, EPA cannot currently grant final approval to a 
maintenance plan that relies in significant part on either of these 
rules.
    On the other hand, as noted above, EPA's recently proposed 
Transport Rule would, if finalized, achieve substantial regional 
reductions of SO2 and NOX emissions. While EPA 
has not made emission estimates for 2022 that are premised on the 
implementation of the proposed Transport Rule, Table 4 above shows 
emission estimates that EPA has made for 2014 that assume the 
implementation of the proposed Transport Rule. These emission estimates 
show a substantial decline in SO2 and NOX 
emissions comparable to that shown in Indiana's maintenance plan. Given 
the substantial degree of control of the various EGUs in the Evansville 
area both currently and projected into the future, EPA finds Indiana's 
projection of such emission declines through 2022 to be appropriate 
forecasts of future emissions, provided EPA promulgates a final 
Transport Rule whose requirements are substantially equivalent to those 
in the proposed rule with respect to continued maintenance of the 
PM2.5 annual standard in the Evansville area.
    In conjunction with the projections for dramatic declines in 
Evansville area emissions of SO2 and NOX 
emissions, Indiana's maintenance plan shows an increase in 
PM2.5 emissions. Therefore, further evaluation is needed to 
judge whether the increase in PM2.5 emissions, in 
combination with the decreases in SO2 and NOX 
emissions, is likely to provide for maintenance of the standard.
    Each of these pollutants is characterized by a different 
relationship between emissions and air quality. Therefore, simply 
summing up the emissions of these various pollutants does not provide a 
meaningful indicator of the combined air quality impact of these 
emission changes. Instead, a more appropriate indicator is the 
percentage change in emissions for each emitted pollutant, weighted 
according to the air quality impact for each.
    For this purpose, EPA examined speciation data available from its 
Air Explorer Web site for 2007 and 2008 for the Evansville area. These 
data suggest that PM2.5 in the Evansville area consists of 
approximately 54 percent sulfate, 7 percent nitrate, 32 percent organic 
particulate, 4 percent miscellaneous inorganic particulate (sometime 
labeled ``crustal particles''), and 4 percent other types of 
particulate matter.
    EPA used a conservative approach that assumes that the full ambient 
concentration of organic particulate matter plus miscellaneous 
inorganic particulate matter will vary in accordance with changes in 
total nonattainment area emissions of directly emitted 
PM2.5. This analysis thus assumes that the entirety of this 
component of ambient PM2.5 will increase by the 24 percent 
that Indiana's maintenance plan projects that directly emitted 
PM2.5 emissions will increase. In this analysis, the 
baseline concentration is conservatively assumed to be 15.0 [mu]g/m\3\, 
of which directly emitted PM2.5 is estimated to include 32 
plus 4 or 36 percent, or 5.4 [mu]g/m\3\. Indiana estimates that 
emissions of directly emitted PM2.5 will increase by 24 
percent from 2005. EPA's assessment assumes that this increase will 
cause a corresponding increase in ambient concentrations of 
PM2.5, which would suggest an increase in the concentration 
of this component by 1.3 [mu]g/m\3\. However, EPA believes that this 
potential increase will be fully compensated by a greater decrease in 
sulfate and nitrate concentrations. The precise decrease in sulfate and 
nitrate concentrations is a complicated result of emission reductions 
not just in the Evansville area but also in many other parts of the 
Eastern United States. Nevertheless, modeling conducted by EPA for the 
proposed Transport Rule estimated that future Evansville area 
concentrations with the Transport Rule as proposed in place would be 
about 4 [mu]g/m\3\ below the standard, and the emission reductions that 
have already occurred have already brought Evansville area 
concentrations to about 13.0 [mu]g/m\3\ (as shown in Table 4 above). 
Therefore, the 1.3 [mu]g/m\3\ increase in the components associated 
with directly emitted PM2.5 would not be expected to yield 
concentrations above the standard. That is, EPA expects that the trends 
in direct emissions of PM2.5 in the Evansville area will not 
prevent the area from maintaining the standard.
    Maintenance of the 1997 annual PM2.5 air quality 
standard in the Evansville area is a function of regional as well as 
local emissions trends. The regional impacts are dominated by the 
impacts of SO2 and NOX emissions. The previous 
section (discussing permanent and

[[Page 29704]]

enforceable emission reductions) showed that the proposed Transport 
Rule could be expected to provide for substantial SO2 and 
NOX emission reductions through 2014, reductions that would 
be maintained throughout and well beyond the period (through 2022) 
addressed in Indiana's maintenance plan. While EPA in its Transport 
Rule rulemaking developed emission projections extending to 2020 only 
for a scenario without regional emission limitations and not for a 
scenario with a Transport Rule in place, the ongoing downward emission 
trend evident in EPA's 2020 emission projections in absence of regional 
emission limitations lends support to Indiana's projection that the 
scenario with regional emission limitations in place will continue to 
have low emissions in 2022. With a Transport Rule as proposed, the caps