Approval and Promulgation of Implementation Plans and Designation of Areas for Air Quality Planning Purposes; North Carolina; Redesignation of the Raleigh-Durham-Chapel Hill 8-Hour Ozone Nonattainment Area to Attainment for Ozone, 56312-56325 [E7-19513]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 72, Number 191 (Wednesday, October 3, 2007)]
[Proposed Rules]
[Pages 56312-56325]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-19513]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R04-OAR-2007-0601-200730; FRL-8477-2]


Approval and Promulgation of Implementation Plans and Designation 
of Areas for Air Quality Planning Purposes; North Carolina; 
Redesignation of the Raleigh-Durham-Chapel Hill 8-Hour Ozone 
Nonattainment Area to Attainment for Ozone

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: On June 7, 2007, the State of North Carolina, through the 
North Carolina Department of Environment and Natural Resources 
(NCDENR), submitted a request to redesignate the Raleigh-Durham-Chapel 
Hill 8-hour ozone nonattainment area to attainment for the 8-hour ozone 
National Ambient Air Quality Standard (NAAQS); and to approve a State 
Implementation Plan (SIP) revision containing a maintenance plan for 
the Raleigh-Durham-Chapel Hill Area. The Raleigh-Durham-Chapel Hill 8-
hour ozone nonattainment area (the ``Triangle Area'') is comprised of 
Durham, Franklin, Granville, Johnston, Orange, Person and Wake Counties 
in their entireties, and Baldwin, Center, New Hope and Williams 
Townships in Chatham County. In this action, EPA is proposing to 
approve the 8-hour ozone redesignation request for the Triangle Area. 
Additionally, EPA is proposing to approve the 8-hour ozone maintenance 
plan for the Triangle Area, including the motor vehicle emissions 
budgets (MVEBs) for nitrogen oxides (NOX) and an 
insignificance determination for volatile organic compounds (VOC) 
emissions from motor vehicles. This proposed approval of North 
Carolina's redesignation request is based on EPA's determination that 
North Carolina has demonstrated that the Triangle Area has met the 
criteria for redesignation to attainment specified in the Clean Air Act 
(CAA), including the determination that the entire Triangle 8-hour 
ozone nonattainment area has attained the 8-hour ozone standard. 
Further, in this action, EPA is also describing the status of its 
transportation conformity adequacy determination for the new 2008 and 
2017 MVEBs for NOX, and for the insignificance determination 
for VOC contribution from motor vehicle emissions to the 8-hour ozone 
pollution, that are contained in the 8-hour ozone maintenance plan for 
the Triangle Area.

[[Page 56313]]


DATES: Comments must be received on or before November 2, 2007.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R04-
OAR-2007-0601, by one of the following methods:
    (a) https://www.regulations.gov: Follow the on-line instructions for 
submitting comments.
    (b) E-mail: ward.nacosta@epa.gov.
    (c) Fax: (404) 562-9019.
    (d) Mail: EPA-R04-OAR-2007-0601, Regulatory Development Section, 
Air Planning Branch, Air, Pesticides and Toxics Management Division, 
U.S. Environmental Protection Agency, Region 4, 61 Forsyth Street, SW., 
Atlanta, Georgia 30303-8960.
    (e) Hand Delivery or Courier: Nacosta C. Ward, Regulatory 
Development Section, Air Planning Branch, Air, Pesticides and Toxics 
Management Division, U.S. Environmental Protection Agency, Region 4, 61 
Forsyth Street, SW., Atlanta, Georgia 30303-8960. Such deliveries are 
only accepted during the Regional Office's normal hours of operation. 
The Regional Office's official hours of business are Monday through 
Friday, 8:30 to 4:30, excluding Federal holidays.
    Instructions: Direct your comments to Docket ID No. EPA-R04-OAR-
2007-0601. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available online at 
www.regulations.gov, including any personal information provided, 
unless the comment includes information claimed to be Confidential 
Business Information (CBI) or other information whose disclosure is 
restricted by statute. Do not submit through www.regulations.gov or e-
mail, information that you consider to be CBI or otherwise protected. 
The 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 www.regulations.gov, 
your e-mail address will be automatically captured and included as part 
of the comment that is placed in the public docket and made available 
on the Internet. If you submit an electronic comment, EPA recommends 
that you include your name and other contact information in the body of 
your comment and with any disk or CD-ROM you submit. If EPA cannot read 
your comment due to technical difficulties and cannot contact you for 
clarification, EPA may not be able to consider your comment. Electronic 
files should avoid the use of special characters, any form of 
encryption, and be free of any defects or viruses. For additional 
information about EPA's public docket visit the EPA Docket Center 
homepage at https://www.epa.gov/epahome/dockets.htm.
    Docket: All documents in the electronic docket are listed in the 
www.regulations.gov index. Although listed in the index, some 
information is not publicly available, i.e., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, is not placed on the Internet and will be 
publicly available only in hard copy form. Publicly available docket 
materials are available either electronically in www.regulations.gov or 
in hard copy at the Regulatory Development Section, Air Planning 
Branch, Air, Pesticides and Toxics Management Division, U.S. 
Environmental Protection Agency, Region 4, 61 Forsyth Street, SW., 
Atlanta, Georgia 30303-8960. EPA requests that if at all possible, you 
contact the person listed in the FOR FURTHER INFORMATION CONTACT 
section to schedule your inspection. The Regional Office's official 
hours of business are Monday through Friday, 8:30 to 4:30, excluding 
Federal holidays.

FOR FURTHER INFORMATION CONTACT: Ms. Nacosta C. Ward of the Regulatory 
Development Section, in the Air Planning Branch, Air, Pesticides and 
Toxics Management Division, U.S. Environmental Protection Agency, 
Region 4, 61 Forsyth Street, SW., Atlanta, Georgia 30303-8960. The 
telephone number is (404) 562-9140. Ms. Nacosta Ward can be reached via 
electronic mail at ward.nacosta@epa.gov.

SUPPLEMENTARY INFORMATION: 

Table of Contents

I. What Proposed Actions Are EPA Taking?
II. What Is the Background for EPA's Proposed Actions?
III. What Are the Criteria for Redesignation?
IV. Why Is EPA Proposing These Actions?
V. What Is the Effect of EPA's Proposed Actions?
VI. What Is EPA's Analysis of the Request?
VII. What Is EPA's Analysis of North Carolina's Proposed VOC 
Insignificance Finding and the Proposed Subarea NOX MVEBs 
for the Triangle Area?
VIII. What Is an Adequacy Determination?
IX. What Is the Status of EPA's Adequacy Determination for the 
Proposed Subarea NOX MVEBs for the Years 2008 and 2017, 
and the VOC Insignificance Determination?
X. Proposed Action on the Redesignation Request and Maintenance Plan 
SIP Revision Including Proposed Approval of the 2008 and 2017 
Subarea NOX MVEBs, and the Proposed VOC Insignificance 
Determination for the Triangle Area
    XI. Statutory and Executive Order Reviews

I. What Proposed Actions Are EPA Taking?

    EPA is proposing to take two related actions, which are summarized 
below and described in greater detail throughout this notice of 
proposed rulemaking: (1) To redesignate the Triangle Area to attainment 
for the 8-hour ozone NAAQS; and (2) to approve North Carolina's 8-hour 
ozone maintenance plan into the North Carolina SIP, including the 
associated MVEBs for NOX and the VOC insignificance 
determination. In addition, and related to today's proposed actions, 
EPA is also notifying the public of the status of EPA's adequacy 
determination for the Triangle Area subarea \1\ NOX MVEBs 
and the insignificance determination for VOC emission contribution from 
motor vehicles to 8-hour ozone pollution in the Triangle Area.
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    \1\ The term ``subarea'' refers to the portion of the area, in a 
nonattainment or maintenance area, for which the MVEB applies. In 
this case, the ``subareas'' are established at the county level so 
this indicates that the MVEBs cover individual counties and also 
indicates to transportation conformity implementers in this area 
that there are separate county-level MVEBs for each county in this 
area. EPA's Companion Guidance for the July 1, 2004, Final 
Transportation Conformity Rule: Conformity Implementation in Multi-
Jurisdictional Nonattainment and Maintenance Areas for Existing and 
New Air Quality Standards explains more about the possible 
geographical extent of a MVEB, how these geographical areas are 
defined, and how transportation conformity is implemented in these 
different geographical areas.
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    First, EPA is proposing to determine that the Triangle Area has 
attained the 8-hour ozone standard, and that the Triangle Area has met 
the other requirements for redesignation under section 107(d)(3)(E) of 
the CAA. EPA is now proposing to approve a request to change the legal 
designation of the Triangle Area from nonattainment to attainment for 
the 8-hour ozone NAAQS.
    Second, EPA is proposing to approve North Carolina's 8-hour ozone 
maintenance plan for the Triangle Area (such approval being one of the 
CAA criteria for redesignation to attainment status). The maintenance 
plan is designed to help keep the Triangle Area in attainment of the 8-
hour ozone NAAQS through 2017. Consistent with the CAA, the maintenance 
plan that EPA is proposing to approve today also includes 2008 and 2017 
subarea MVEBs for NOX, and an insignificance determination 
regarding the contribution of VOC emissions from

[[Page 56314]]

motor vehicles to the ozone pollution in the Triangle Area. Today, EPA 
is proposing to approve (into the North Carolina SIP) the 2008 and 2017 
subarea NOX MVEBs and the VOC insignificance determination, 
that are included as part of North Carolina's maintenance plan for the 
Triangle Area for the 8-hour ozone NAAQS. The VOC insignificance 
determination applies to the entire Triangle Area, whereas the 
NOX MVEBs are subarea MVEBs that apply to individual 
counties within the Triangle Area. Please see Section V of this 
rulemaking for a listing of the MVEBs for these individual counties.
    Third, EPA is also notifying the public of the status of EPA's 
adequacy process for the newly-established 2008 and 2017 subarea 
NOX MVEBs, and its insignificance determination for VOC for 
the Triangle Area. The adequacy comment period for the Triangle Area's 
2008 and 2017 subarea NOX MVEBs, and the VOC insignificance 
determination began on March 21, 2007, with EPA's posting of the 
availability of North Carolina's maintenance plan submittal on EPA's 
Adequacy Web site (https://www.epa.gov/otaq/stateresources/transconf/
currsips.htm). The adequacy comment period for these subarea MVEBs, and 
the VOC insignificance determination closed on April 20, 2007. No 
adverse comments were received during the adequacy public comment 
period. Please see section VIII of this proposed rulemaking for further 
explanation of this process, and for more details on the MVEBs and the 
VOC insignificance determination.
    Today's notice of proposed rulemaking is in response to North 
Carolina's June 7, 2007, SIP submittal, which supersedes North 
Carolina's March 12, 2007, submittal that included a request for 
parallel processing. The June 7, 2007, submittal requests the 
redesignation of the Triangle Area, and includes a SIP revision 
addressing the specific issues summarized above and the necessary 
elements for redesignation described in section 107(d)(3)(E) of the 
CAA.

II. What Is the Background for EPA's Proposed Actions?

    Ground-level ozone is not emitted directly by sources. Rather, 
emissions of NOX and VOC react in the presence of sunlight 
to form ground-level ozone. NOX and VOC are referred to as 
precursors of ozone. The CAA establishes a process for air quality 
management through the NAAQS.
    On July 18, 1997, EPA promulgated a revised 8-hour ozone standard 
of 0.08 parts per million (ppm). This new standard is more stringent 
than the previous 1-hour ozone standard. Under EPA regulations at 40 
CFR part 50, the 8-hour ozone standard is attained when the 3-year 
average of the annual fourth highest daily maximum 8-hour average 
ambient air quality ozone concentrations is less than or equal to 0.08 
ppm (i.e., 0.084 ppm when rounding is considered). (See, 69 FR 23857 
(April 30, 2004) for further information.) Ambient air quality 
monitoring data for the 3-year period must meet a data completeness 
requirement. The ambient air quality monitoring data completeness 
requirement is met when the average percent of days with valid ambient 
monitoring data is greater than 90 percent, and no single year has less 
than 75 percent data completeness as determined in Appendix I of part 
50. Specifically, section 2.3 of 40 CFR part 50, Appendix I, 
``Comparisons with the Primary and Secondary Ozone Standards'' states:

    The primary and secondary ozone ambient air quality standards 
are met at an ambient air quality monitoring site when the 3-year 
average of the annual fourth-highest daily maximum 8-hour average 
ozone concentration is less than or equal to 0.08 ppm. The number of 
significant figures in the level of the standard dictates the 
rounding convention for comparing the computed 3-year average annual 
fourth-highest daily maximum 8-hour average ozone concentration with 
the level of the standard. The third decimal place of the computed 
value is rounded, with values equal to or greater than 5 rounding 
up. Thus, a computed 3-year average ozone concentration of 0.085 ppm 
is the smallest value that is greater than 0.08 ppm.

    The CAA required EPA to designate as nonattainment any area that 
was violating the 8-hour ozone NAAQS based on the three most recent 
years of ambient air quality data. The Triangle 8-hour ozone 
nonattainment area was designated using 2001-2003 ambient air quality 
data. The Federal Register document making these designations was 
signed on April 15, 2004, and published on April 30, 2004 (69 FR 
23857).
    The CAA contains two sets of provisions--subpart 1 and subpart 2--
that address planning and control requirements for ozone nonattainment 
areas. (Both are found in title I, part D.) Subpart 1 (which EPA refers 
to as ``basic'' nonattainment) contains general, less prescriptive, 
requirements for nonattainment areas for any pollutant--including 
ozone--governed by a NAAQS. Subpart 2 (which EPA refers to as 
``classified'' nonattainment) provides more specific requirements for 
certain ozone nonattainment areas. Some 8-hour ozone nonattainment 
areas are subject only to the provisions of subpart 1. Other 8-hour 
ozone nonattainment areas are also subject to the provisions of subpart 
2. Under EPA's Phase 1 8-hour ozone implementation rule (69 FR 23857) 
(Phase 1 Rule), signed on April 15, 2004, and published April 30, 2004, 
an area was classified under subpart 2 based on its 8-hour ozone design 
value (i.e., the 3-year average of the annual fourth-highest daily 
maximum 8-hour average ozone concentrations), if it had a 1-hour design 
value at or above 0.121 ppm (the lowest 1-hour design value in Table 1 
of subpart 2). All other areas are covered under subpart 1, based upon 
their 8-hour ambient air quality design values.
    Durham and Wake Counties, and the Dutchville Township portion of 
Granville County were originally designated as a moderate nonattainment 
area for the 1-hour ozone standard on November 6, 1991 (56 FR 56694). 
Durham and Wake Counties, and the Dutchville Township portion of 
Granville County were redesignated as attainment for the 1-hour ozone 
standard on April 18, 1994 (59 FR 18300). On April 30, 2004, EPA 
designated the Triangle Area (of which Durham and Wake Counties, and 
the Dutchville Township portion of Granville County are a part) as a 
``basic'' 8-hour ozone nonattainment area (see, 69 FR 23857, April 30, 
2004). Thus, on June 7, 2007, when North Carolina submitted its final 
redesignation request, the Triangle Area was classified under subpart 1 
of the CAA, and was obligated to meet only the subpart 1 requirements.
    Various aspects of EPA's Phase 1 Rule were challenged in court. On 
December 22, 2006, the U.S. Court of Appeals for the District of 
Columbia Circuit (D.C. Circuit Court) vacated EPA's Phase 1 Rule (69 FR 
23951, April 30, 2004). South Coast Air Quality Management Dist. 
(SCAQMD) v. EPA, 472 F.3d 882 (D.C. Cir. 2006). On June 8, 2007, in 
response to several petitions for rehearing, the D.C. Circuit Court 
clarified that the Phase 1 Rule was vacated only with regard to those 
parts of the Rule that had been successfully challenged. Therefore, the 
Phase 1 Rule provisions related to classifications for areas currently 
classified under subpart 2 of title I, part D of the CAA as 8-hour 
nonattainment areas, the 8-hour attainment dates and the timing for 
emissions reductions needed for attainment of the 8-hour ozone NAAQS 
remain effective. The June 8th decision left intact the Court's 
rejection of EPA's reasons for implementing the 8-hour standard in 
certain nonattainment areas

[[Page 56315]]

under subpart 1 in lieu of subpart 2. By limiting the vacatur, the 
Court let stand EPA's revocation of the 1-hour standard and those anti-
backsliding provisions of the Phase 1 Rule that had not been 
successfully challenged. The June 8th decision reaffirmed the December 
22, 2006, decision that EPA had improperly failed to retain measures 
required for 1-hour nonattainment areas under the anti-backsliding 
provisions of the regulations: (1) Nonattainment area New Source Review 
(NSR) requirements based on an area's 1-hour nonattainment 
classification; (2) Section 185 penalty fees for 1-hour severe or 
extreme nonattainment areas; and (3) measures to be implemented 
pursuant to section 172(c)(9) or 182(c)(9) of the CAA, on the 
contingency of an area not making reasonable further progress toward 
attainment of the 1-hour NAAQS, or for failure to attain that NAAQS. 
The June 8th decision clarified that the Court's reference to 
conformity requirements for anti-backsliding purposes was limited to 
requiring the continued use of 1-hour motor vehicle emissions budgets 
until 8-hour budgets were available for 8-hour conformity 
determinations, which is already required under EPA's conformity 
regulations. The Court thus clarified that 1-hour conformity 
determinations are not required for anti-backsliding purposes.
    This section sets forth EPA's views on the potential effect of the 
Court's rulings on this proposed redesignation action. For the reasons 
set forth below, EPA does not believe that the Court's rulings alter 
any requirements relevant to this redesignation action so as to 
preclude redesignation, and do not prevent EPA from proposing or 
ultimately finalizing this redesignation. EPA believes that the Court's 
December 22, 2006, and June 8, 2007, decisions impose no impediment to 
moving forward with redesignation of the Triangle Area to attainment, 
because even in light of the Court's decisions, redesignation is 
appropriate under the relevant redesignation provisions of the CAA and 
longstanding policies regarding redesignation requests.
    With respect to the 8-hour standard, the Court's ruling rejected 
EPA's reasons for classifying areas under subpart 1 for the 8-hour 
standard, and remanded that matter to the Agency. Consequently, it is 
possible that this Area could, during a remand to EPA, be reclassified 
under subpart 2. Although any future decision by EPA to classify this 
area under subpart 2 might trigger additional future requirements for 
the area, EPA believes that this does not mean that redesignation 
cannot now go forward. This belief is based upon (1) EPA's longstanding 
policy of evaluating requirements in accordance with the requirements 
due at the time the request is submitted and (2) consideration of the 
inequity of applying retroactively any requirements that might in the 
future be applied.
    First, at the time the redesignation request was submitted, the 
Triangle Area was classified under subpart 1 and was obligated to meet 
only subpart 1 requirements. Under EPA's longstanding interpretation of 
section 107(d)(3)(E) of the CAA, to qualify for redesignation, states 
requesting redesignation to attainment must meet only the relevant SIP 
requirements that came due prior to the submittal of a complete 
redesignation request. September 4, 1992, Calcagni Memorandum 
(``Procedures for Processing Requests to Redesignate Areas to 
Attainment,'' Memorandum from John Calcagni, Director, Air Quality 
Management Division). See also, Michael Shapiro Memorandum, September 
17, 1993, and 60 FR 12459, 12465-66 (March 7, 1995) (Redesignation of 
Detroit-Ann Arbor, Michigan). See, Sierra Club v. EPA, 375 F.3d 537 
(7th Cir. 2004) (upholding this interpretation). See, e.g. also, 68 FR 
25418, 25424, 25427 (May 12, 2003) (redesignation of St. Louis, 
Missouri).
    Moreover, it would be inequitable to retroactively apply any new 
SIP requirements that were not applicable at the time the request was 
submitted. The D.C. Circuit Court has recognized the inequity in such 
retroactive rulemaking, (Sierra Club v. Whitman, 285 F. 3d 63 (D.C. 
Cir. 2002)), in which the Court upheld a district court's ruling 
refusing to make retroactive an EPA determination of nonattainment that 
was past the statutory due date. Such a determination would have 
resulted in the imposition of additional requirements on the area. The 
Court stated: ``Although EPA failed to make the nonattainment 
determination within the statutory time frame, Sierra Club's proposed 
solution only makes the situation worse. Retroactive relief would 
likely impose large costs on the states, which would face fines and 
suits for not implementing air pollution prevention plans in 1997, even 
though they were not on notice at the time.'' Id. at 68. Similarly 
here, it would be unfair to penalize the area by applying to it for 
purposes of redesignation, additional SIP requirements under subpart 2 
that were not in effect at the time it submitted its redesignation 
request.
    With respect to the requirements under the 1-hour standard ozone 
standard, only the Durham and Wake Counties, and the Dutchville 
Township portion of Granville County of the Triangle Area were 
originally designated as a moderate nonattainment area for the 1-hour 
ozone standard on November 6, 1991 (56 FR 56694); the remainder of the 
Triangle Area was designated as attainment. Durham and Wake Counties, 
and the Dutchville Township portion of Granville County were 
redesignated as attainment for the 1-hour ozone standard on April 18, 
2004 (59 FR 18300). Therefore, the entire Triangle Area was 
redesignated to attainment of the 1-hour ozone standard prior to its 
nonattainment designation for the 8-hour ozone standard. As a result, 
the Triangle Area is considered to be a 1-hour attainment area subject 
to a CAA section 175A maintenance plan for the 1-hour standard. The 
D.C. Circuit Court's decisions do not impact redesignation requests for 
these types of areas, except to the extent that the Court, in its June 
8th decision, clarified that for those areas with 1-hour MVEBs in their 
maintenance plans, anti-backsliding requires that those 1-hour budgets 
must be used for 8-hour conformity determinations until they are 
replaced by 8-hour budgets. To meet this requirement, conformity 
determinations in such areas must comply with the applicable 
requirements of EPA's conformity regulations at 40 CFR part 93.
    First, there are no conformity requirements relevant for the 
Triangle Area redesignation request, such as a transportation 
conformity SIP. It is EPA's longstanding policy that it is reasonable 
to interpret the conformity SIP requirements as not applying for 
purposes of evaluating a redesignation request under section 107(d) 
because state conformity rules are still required after redesignation, 
and Federal conformity rules apply where state rules have not been 
approved. See, 40 CFR 51.390; see also, Wall v. EPA, 265 F.3d 426 (6th 
Cir. 2001) (upholding EPA's interpretation). See also, 60 FR 62748 
(Dec. 7, 1995) (redesignation of Tampa, Florida). Durham and Wake 
Counties, and the Dutchville Township portion of Granville County, 
currently have a fully approved 1-hour ozone transportation conformity 
SIP, which was approved on December 27, 2002 (67 FR 78983).
    Second, with regard to the three other anti-backsliding provisions 
for the 1-hour standard that the D.C. Circuit Court found were not 
properly retained, Durham and Wake Counties, and the Dutchville 
Township portion of Granville County comprise an attainment area 
subject to a maintenance plan for the 1-hour standard, and the NSR, 
contingency measure (pursuant to section 172(c)(9) or 182(c)(9)), and 
fee provision

[[Page 56316]]

requirements no longer apply to this area because it was redesignated 
to attainment of the 1-hour standard. As a result, the decisions in 
SCAQMD should not alter any requirements that would preclude EPA from 
finalizing the redesignation of the Triangle Area to attainment for the 
8-hour ozone standard.
    As noted earlier, in 2006, the ambient ozone data for the Triangle 
Area indicated no further violations of the 8-hour ozone NAAQS, using 
data from the 3-year period of 2004-2006 to demonstrate attainment. As 
a result, on June 7, 2007, North Carolina requested redesignation of 
the Triangle Area to attainment for the 8-hour ozone NAAQS. The 
redesignation request included three years of complete, quality-assured 
ambient air quality data for the ozone seasons (April 1st until October 
31st) of 2004-2006, indicating that the 8-hour ozone NAAQS has been 
achieved for the entire Triangle Area. Under the CAA, nonattainment 
areas may be redesignated to attainment if sufficient, complete, 
quality-assured data is available for the Administrator to determine 
that the area has attained the standard and the area meets the other 
CAA redesignation requirements in section 107(d)(3)(E).

III. What Are the Criteria for Redesignation?

    The CAA provides the requirements for redesignating a nonattainment 
area to attainment. Specifically, section 107(d)(3)(E) of the CAA 
allows for redesignation providing that: (1) The Administrator 
determines that the area has attained the applicable NAAQS; (2) the 
Administrator has fully approved the applicable implementation plan for 
the area under section 110(k); (3) the Administrator determines that 
the improvement in air quality is due to permanent and enforceable 
reductions in emissions resulting from implementation of the applicable 
SIP and applicable Federal air pollutant control regulations and other 
permanent and enforceable reductions; (4) the Administrator has fully 
approved a maintenance plan for the area as meeting the requirements of 
section 175A; and, (5) the state containing such area has met all 
requirements applicable to the area under section 110 and part D of the 
CAA.
    EPA provided guidance on redesignation in the General Preamble for 
the Implementation of Title I of the CAA Amendments of 1990, on April 
16, 1992 (57 FR 13498), and supplemented this guidance on April 28, 
1992 (57 FR 18070). EPA has provided further guidance on processing 
redesignation requests in the following documents:
    1. ``Ozone and Carbon Monoxide Design Value Calculations,'' 
Memorandum from Bill Laxton, Director, Technical Support Division, June 
18, 1990;
    2. ``Maintenance Plans for Redesignation of Ozone and Carbon 
Monoxide Nonattainment Areas,'' Memorandum from G. T. Helms, Chief, 
Ozone/Carbon Monoxide Programs Branch, April 30, 1992;
    3. ``Contingency Measures for Ozone and Carbon Monoxide (CO) 
Redesignations,'' Memorandum from G. T. Helms, Chief, Ozone/Carbon 
Monoxide Programs Branch, June 1, 1992;
    4. ``Procedures for Processing Requests to Redesignate Areas to 
Attainment,'' Memorandum from John Calcagni, Director, Air Quality 
Management Division, September 4, 1992 (hereafter referred to as the 
``Calcagni Memorandum'');
    5. ``State Implementation Plan (SIP) Actions Submitted in Response 
to Clean Air Act (ACT) Deadlines,'' Memorandum from John Calcagni, 
Director, Air Quality Management Division, October 28, 1992;
    6. ``Technical Support Documents (TSD's) for Redesignation of Ozone 
and Carbon Monoxide (CO) Nonattainment Areas,'' Memorandum from G. T. 
Helms, Chief, Ozone/Carbon Monoxide Programs Branch, August 17, 1993;
    7. ``State Implementation Plan (SIP) Requirements for Areas 
Submitting Requests for Redesignation to Attainment of the Ozone and 
Carbon Monoxide (CO) National Ambient Air Quality Standards (NAAQS) On 
or After November 15, 1992,'' Memorandum from Michael H. Shapiro, 
Acting Assistant Administrator for Air and Radiation, September 17, 
1993;
    8. ``Use of Actual Emissions in Maintenance Demonstrations for 
Ozone and CO Nonattainment Areas,'' Memorandum from D. Kent Berry, 
Acting Director, Air Quality Management Division, November 30, 1993;
    9. ``Part D New Source Review (Part D NSR) Requirements for Areas 
Requesting Redesignation to Attainment,'' Memorandum from Mary D. 
Nichols, Assistant Administrator for Air and Radiation, October 14, 
1994; and
    10. ``Reasonable Further Progress, Attainment Demonstration, and 
Related Requirements for Ozone Nonattainment Areas Meeting the Ozone 
National Ambient Air Quality Standard,'' Memorandum from John S. Seitz, 
Director, Office of Air Quality Planning and Standards, May 10, 1995.

IV. Why Is EPA Proposing These Actions?

    On June 7, 2007, North Carolina requested redesignation of the 
Triangle 8-hour ozone nonattainment area to attainment for the 8-hour 
ozone standard. EPA's evaluation indicates that North Carolina has 
demonstrated that the Triangle Area has attained the standard and has 
met the requirements for redesignation set forth in section 
107(d)(3)(E) of the CAA. EPA is also announcing the status of its 
adequacy determination for the 2008 and 2017 subarea NOX 
MVEBs, and the VOC insignificance determination, which are relevant to 
the requested redesignation.

V. What Is the Effect of EPA's Proposed Actions?

    EPA's proposed actions establish the bases upon which EPA may take 
final action on the issues being proposed for approval today. Approval 
of North Carolina's redesignation request would change the legal 
designation of the Durham, Franklin, Granville, Johnston, Orange, 
Person and Wake Counties in their entireties, and Baldwin, Center, New 
Hope and Williams Townships in Chatham County for the 8-hour ozone 
NAAQS found at 40 CFR part 81. Approval of North Carolina's request 
would also incorporate into the North Carolina SIP, a plan for the 
Triangle Area for maintaining the 8-hour ozone NAAQS in the Area 
through 2017. This maintenance plan includes contingency measures to 
remedy future violations of the 8-hour ozone NAAQS. The maintenance 
plan also establishes subarea NOX MVEBs and provides a VOC 
insignificance determination for the Triangle Area. The following Table 
identifies the subarea NOX MVEBs for the year 2008 and 2017 
for this Area.

                  Table 1.--Triangle Subarea NOX MVEBS
                           [Kilograms per day]
------------------------------------------------------------------------
                       County                           2008      2017
------------------------------------------------------------------------
Chatham.............................................     1,565       948
Durham..............................................    13,106     4,960
Franklin............................................     2,048     1,139
Graham..............................................     4,649     1,714
Johnston............................................    12,583     5,958
Orange..............................................     9,933     3,742
Person..............................................     1,359       791
Wake................................................    36,615    16,352
------------------------------------------------------------------------

    Approval of North Carolina's maintenance plan would also result in 
approval of the subarea NOX MVEBs, and the VOC 
insignificance determination. Additionally, EPA is

[[Page 56317]]

notifying the public of the status of its adequacy determination for 
the 2008 and 2017 subarea NOX MVEBs, and its VOC 
insignificance determination, pursuant to 40 CFR 93.118(f)(1).

VI. What Is EPA's Analysis of the Request?

    EPA is proposing to make the determination that the Triangle Area 
has attained the 8-hour ozone standard, and that all other 
redesignation criteria have been met for the Triangle Area. The basis 
for EPA's determination for the area is discussed in greater detail 
below.

Criteria (1)--The Triangle Area Has Attained the 8-Hour Ozone NAAQS

    EPA is proposing to determine that the Triangle Area has attained 
the 8-hour ozone NAAQS. For ozone, an area may be considered to be 
attaining the 8-hour ozone NAAQS if there are no violations, as 
determined in accordance with 40 CFR 50.10 and Appendix I of part 50, 
based on three complete, consecutive calendar years of quality-assured 
air quality monitoring data. To attain this standard, the 3-year 
average of the fourth-highest daily maximum 8-hour average ozone 
concentrations measured at each monitor within an area over each year 
must not exceed 0.08 ppm. Based on the rounding convention described in 
40 CFR part 50, Appendix I, the standard is attained if the design 
value is 0.084 ppm or below. The data must be collected and quality-
assured in accordance with 40 CFR part 58, and recorded in the EPA Air 
Quality System (AQS). The monitors generally should have remained at 
the same location for the duration of the monitoring period required 
for demonstrating attainment.
    EPA reviewed ozone monitoring data from ambient ozone monitoring 
stations in the Triangle Area for the ozone season from 2004-2006. This 
data has been quality assured and is recorded in AQS. The fourth high 
averages for 2004, 2005 and 2006, and the 3-year average of these 
values (i.e., design values), are summarized in the following Table:

                                                                   Table 2.--Annual 4th Max High and Design Value Concentration for 8-Hour Ozone for the Triangle Area
                                                                                                         [In parts per million]
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                 COUNTY                           Chatham                 Durham                 Franklin                Granville               Johnston                 Person                               Wake
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Pittsboro  (37-  West Johnston  (37-037-0004)          i>37-063-0013)          i>37-069-0001)             077-0001)            i>37-101-0002)          i>37-145-0003)          i>37-183-0014)          i>37-183-0016)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
2004....................................                0.068                   0.074                   0.077                   0.081                   0.074                   0.076                   0.075                   0.077
2005....................................                0.079                   0.076                   0.080                   0.085                   0.083                   0.079                   0.082                   0.085
2006....................................                0.066                   0.075                   0.074                   0.075                   0.072                   0.071                   0.078                   0.072
Design Value............................                0.071                   0.075                   0.077                   0.080                   0.076                   0.075                   0.078                   0.078
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    As discussed above, the design value for an area is the highest 
design value recorded at any monitor in the area. Therefore, the design 
value for the Triangle Area is 0.080 ppm, which meets the standard as 
described above. As discussed in more detail below, North Carolina has 
committed to continue monitoring in this area in accordance with 40 CFR 
part 58. The data submitted by North Carolina provides an adequate 
demonstration that the Triangle Area has attained the 8-hour ozone 
NAAQS.

Criteria (2)--North Carolina has a Fully Approved SIP Under Section 
110(k) for the Triangle Area and Criteria (5)--has met all Applicable 
Requirements Under Section 110 and Part D of the CAA

    Below is a summary of how these two criteria were met.
    EPA has determined that North Carolina has met all applicable SIP 
requirements for the Triangle Area under section 110 of the CAA 
(general SIP requirements). EPA has also determined that the North 
Carolina SIP satisfies the criterion that it meet applicable SIP 
requirements under part D of title I of the CAA (requirements specific 
to subpart 1 basic 8-hour ozone nonattainment areas) in accordance with 
section 107(d)(3)(E)(v). In addition, EPA has determined that the SIP 
is fully approved with respect to all applicable requirements in 
accordance with section 107(d)(3)(E)(ii). In making these 
determinations, EPA ascertained which requirements are applicable to 
the area and that if applicable, they are fully approved under section 
110(k). SIPs must be fully approved only with respect to applicable 
requirements.
a. The Triangle Area has met all Applicable Requirements Under Section 
110 and Part D of the CAA
    The September 4, 1992, Calcagni Memorandum (see ``Procedures for 
Processing Requests to Redesignate Areas to Attainment,'' Memorandum 
from John Calcagni, Director, Air Quality Management Division, 
September 4, 1992) describes EPA's interpretation of section 
107(d)(3)(E). Under this interpretation, to qualify for redesignation, 
states requesting redesignation to attainment must meet only the 
relevant CAA requirements that come due prior to the submittal of a 
complete redesignation request. See also, Michael Shapiro Memorandum, 
(``SIP Requirements for Areas Submitting Requests for Redesignation to 
Attainment of the Ozone and Carbon Monoxide NAAQS On or After November 
15, 1992,'' September 17, 1993), and 60 FR 12459, 12465-66 (March 7, 
1995) (redesignation of Detroit-Ann Arbor, Michigan). Applicable 
requirements of the CAA that come due subsequent to the area's 
submittal of a complete redesignation request remain applicable until a 
redesignation is approved, but are not required as a prerequisite to 
redesignation. See, section 175A(c) of the CAA; Sierra Club, 375 F.3d 
537; see also, 68 FR 25424, 25427 (May 12, 2003) (redesignation of St. 
Louis, Missouri).
    General SIP requirements. Section 110(a)(2) of title I of the CAA 
delineates the general requirements for a SIP, which include 
enforceable emissions limitations and other control measures, means, or 
techniques, provisions for the establishment and operation of 
appropriate devices necessary to collect data on ambient air quality, 
and programs to enforce the limitations. General SIP elements and 
requirements are delineated in section 110(a)(2) of title I, part A of 
the CAA. These requirements include, but are not limited to, the 
following: submittal of a SIP that has been adopted by the state after 
reasonable public notice and hearing; provisions for establishment and 
operation of appropriate procedures needed to monitor ambient air 
quality; implementation of a source permit program; provisions for the 
implementation of part C requirements (Prevention of Significant 
Deterioration (PSD)) and provisions for the implementation of part D 
requirements (NSR permit programs); provisions for

[[Page 56318]]

air pollution modeling; and provisions for public and local agency 
participation in planning and emission control rule development.
    Section 110(a)(2)(D) requires that SIPs contain certain measures to 
prevent sources in a state from significantly contributing to air 
quality problems in another state. To implement this provision, EPA has 
required certain states to establish programs to address the transport 
of air pollutants (NOX SIP Call, Clean Air Interstate Rule 
(CAIR)). EPA has also found, generally, that states have not submitted 
timely SIPs under section 110(a)(1) to meet the interstate transport 
requirements of section 110(a)(2)(D)(i). However, the section 
110(a)(2)(D) requirements for a state are not linked with a particular 
nonattainment area's designation and classification in that state. EPA 
believes that the requirements linked with a particular nonattainment 
area's designation and classifications are the relevant measures to 
evaluate in reviewing a redesignation request. The transport SIP 
submittal requirements, where applicable, continue to apply to a state 
regardless of the designation of any one particular area in the state. 
Thus, we do not believe that the CAA's interstate transport 
requirements should be construed to be applicable requirements for 
purposes of redesignation.
    In addition, EPA believes that the other section 110 elements not 
connected with nonattainment plan submissions and not linked with an 
area's attainment status are not applicable requirements for purposes 
of redesignation. The area will still be subject to these requirements 
after the area is redesignated. The section 110 and part D 
requirements, which are linked with a particular area's designation and 
classification, are the relevant measures to evaluate in reviewing a 
redesignation request. This approach is consistent with EPA's existing 
policy on applicability (i.e., for redesignations) of conformity and 
oxygenated fuels requirements, as well as with section 184 ozone 
transport requirements. See, Reading, Pennsylvania, proposed and final 
rulemakings (61 FR 53174-53176, October 10, 1996), (62 FR 24826, May 7, 
1997); Cleveland-Akron-Loraine, Ohio, final rulemaking (61 FR 20458, 
May 7, 1996); and Tampa, Florida, final rulemaking at (60 FR 62748, 
December 7, 1995). See also, the discussion on this issue in the 
Cincinnati, Ohio redesignation (65 FR 37890, June 19, 2000), and in the 
Pittsburgh, Pennsylvania redesignation (66 FR 50399, October 19, 2001).
    EPA believes that section 110 elements not linked to the area's 
nonattainment status are not applicable for purposes of redesignation. 
Any section 110 requirements that are linked to the Part D requirements 
for 8-hour ozone nonattainment areas are not yet due, since, as 
explained below, no part D requirements for 8-hour standard became due 
prior to submission of the redesignation request. Therefore, as 
discussed above, for purposes of redesignation, they are not considered 
applicable requirements. Nonetheless, EPA notes it has previously 
approved provisions in the North Carolina SIP addressing section 110 
elements under the 1-hour ozone NAAQS (See, 51 FR 19834, June 3, 1986). 
EPA believes that the section 110 SIP approved for the 1-hour ozone 
NAAQS is also sufficient to meet the requirements under the 8-hour 
ozone NAAQS (as well as satisfying the issues raised by the D.C. 
Circuit Court in the SCAQMD case).
    Part D requirements. EPA has also determined that the North 
Carolina SIP meets applicable SIP requirements under part D of the CAA 
since no requirements became due prior to the submission of the Area's 
redesignation request. Sections 172-176 of the CAA, found in subpart 1 
of part D, set forth the basic nonattainment requirements applicable to 
all nonattainment areas. Section 182 of the CAA, found in subpart 2 of 
part D, establishes additional specific requirements depending on the 
area's nonattainment classification. Subpart 2 is not applicable to the 
Triangle Area.
    Part D, subpart 1 applicable SIP requirements. For purposes of 
evaluating this redesignation request, the applicable part D, subpart 1 
SIP requirements for all nonattainment areas are contained in sections 
172(c)(1)-(9). A thorough discussion of the requirements contained in 
section 172 can be found in the General Preamble for Implementation of 
title I (57 FR 13498). No requirements applicable for purposes of 
redesignation under part D became due prior to the submission of the 
redesignation request, and therefore none are applicable to the Area 
for purposes of redesignation. For example, the requirements for an 
attainment demonstration that meets the requirements of section 
172(c)(1) are not yet applicable, nor are the requirements for 
Reasonably Achievable Control Technology (RACT) and Reasonably 
Available Control Measures (RACM) (section 172(c)(1)), reasonable 
further progress (RFP) (section 172(c)(2)), and contingency measures 
(section 172(c)(9)).
    In addition to the fact that no part D requirements applicable for 
purposes of redesignation became due prior to submission of the 
redesignation request and therefore are not applicable, EPA believes it 
is reasonable to interpret the conformity and NSR requirements as not 
requiring approval prior to redesignation.
    Section 176 Conformity Requirements. Section 176(c) of the CAA 
requires states to establish criteria and procedures to ensure that 
Federally supported or funded projects conform to the air quality 
planning goals in the applicable SIP. The requirement to determine 
conformity applies to transportation plans, programs and projects 
developed, funded or approved under title 23 of the United States Code 
(U.S.C.) and the Federal Transit Act (transportation conformity) as 
well as to all other Federally supported or funded projects (general 
conformity). State conformity revisions must be consistent with Federal 
conformity regulations relating to consultation, enforcement and 
enforceability that the CAA required the EPA to promulgate.
    EPA believes it is reasonable to interpret the conformity SIP 
requirements as not applying for purposes of evaluating the 
redesignation request under section 107(d) because state conformity 
rules are still required after redesignation and Federal conformity 
rules apply where state rules have not been approved. See, Wall, 265 
F.3d 426 (upholding this interpretation). See also, 60 FR 62748 
(December 7, 1995, Tampa, Florida).
    NSR Requirements. EPA has also determined that areas being 
redesignated need not comply with the requirement that a NSR program be 
approved prior to redesignation, provided that the area demonstrates 
maintenance of the standard without a part D NSR program in effect 
since PSD requirements will apply after redesignation. The 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 (Part D NSR) Requirements for Areas 
Requesting Redesignation to Attainment.'' North Carolina has 
demonstrated that the Triangle Area will be able to maintain the 
standard without a part D NSR program in effect, and therefore, North 
Carolina need not have a fully approved part D NSR program prior to 
approval of the redesignation request. North Carolina's PSD program 
will become effective in the Triangle Area upon redesignation to 
attainment. See, rulemakings for Detroit, Michigan (60

[[Page 56319]]

FR 12467-12468, March 7, 1995); Cleveland-Akron-Lorraine, Ohio (61 FR 
20458, 20469-70, May 7, 1996); Louisville, Kentucky (66 FR 53665, 
October 23, 2001); Grand Rapids, Michigan (61 FR 31834-31837, June 21, 
1996). Thus, the Triangle Area has satisfied all applicable 
requirements for purposes of redesignation under section 110 and part D 
of the CAA.
b. The Triangle Area Has a Fully Approved Applicable SIP Under Section 
110(k) of the CAA
    EPA has fully approved the applicable North Carolina SIP for the 
Triangle Area, under section 110(k) of the CAA for all requirements 
applicable for purposes of redesignation. EPA may rely on prior SIP 
approvals in approving a redesignation request, see Calcagni Memorandum 
at p. 3; Southwestern Pennsylvania Growth Alliance v. Browner, 144 F.3d 
984, 989-90 (6th Cir. 1998); Wall, 265 F.3d 426, plus any additional 
measures it may approve in conjunction with a redesignation action. 
See, 68 FR 25426 (May 12, 2003) and citations therein. Following 
passage of the CAA of 1970, North Carolina has adopted and submitted, 
and EPA has fully approved at various times, provisions addressing the 
various 1-hour ozone standard SIP elements applicable in the Triangle 
Area (59 FR 18300, April 18, 1994; and 69 FR 56163, September 20, 
2004).
    As indicated above, 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 redesignation. EPA also believes that since the part D 
requirements applicable for purposes of redesignation did not become 
due prior to submission of the redesignation request, they also are 
therefore not applicable requirements for purposes of redesignation.

Criteria (3)--The air quality improvement in the Triangle Area is due 
to permanent and enforceable reductions in emissions resulting from 
implementation of the SIP and applicable Federal air pollution control 
regulations and other permanent and enforceable reductions

    EPA believes that North Carolina has demonstrated that the observed 
air quality improvement in the Triangle Area is due to permanent and 
enforceable reductions in emissions resulting from implementation of 
the SIP, Federal measures, and other state adopted measures. 
Additionally, new emissions control programs for fuels and motor 
vehicles will help ensure a continued decrease in emissions throughout 
the region.

          Table 3.--Triangle Area Emission Reductions Programs
------------------------------------------------------------------------
 
-------------------------------------------------------------------------
Mobile Sources
   Tier 2 Vehicle Standards
   Heavy Duty Gasoline and Diesel Highway Vehicle Standards
Nonroad Mobile Sources
   Large Nonroad Diesel Engines Rule
   Spark Ignition Engines and Recreational Standards
State and Local Measures
   Inspection and Maintenance (I/M) Program in Clean Air Bill
   NOX SIP Call
   Clean Smokestacks Act
   Opening Burning Ban
   Air Toxics Control Program
   Prevention of Significant Deterioration
   Heavy Duty Diesel Engine Gap Filling Rule
------------------------------------------------------------------------

Criteria (4)--The area has a fully approved maintenance plan pursuant 
to section 175A of the CAA

    In its request to redesignate the Triangle Area to attainment, 
North Carolina submitted a SIP revision to provide for the maintenance 
of the 8-hour ozone NAAQS for at least 10 years after the effective 
date of redesignation to attainment.
a. What is required in a maintenance plan?
    Section 175A of the CAA sets forth the elements of a maintenance 
plan for areas seeking redesignation from nonattainment to attainment. 
Under section 175A, the plan must demonstrate continued attainment of 
the applicable NAAQS for at least 10 years after the Administrator 
approves a redesignation to attainment. Eight years after the 
redesignation, the State of North Carolina must submit a revised 
maintenance plan, which demonstrates that attainment will continue to 
be maintained for the 10 years following the initial 10-year period. To 
address the possibility of future NAAQS violations, the maintenance 
plan must contain such contingency measures, with a schedule for 
implementation as EPA deems necessary to assure prompt correction of 
any future 8-hour ozone violations. Section 175A of the CAA sets forth 
the elements of a maintenance plan for areas seeking redesignation from 
nonattainment to attainment. The Calcagni Memorandum provides 
additional guidance on the content of a maintenance plan. The Calcagni 
Memorandum explains that an ozone maintenance plan should address five 
requirements: the attainment emissions inventory, maintenance 
demonstration, monitoring, verification of continued attainment, and a 
contingency plan. As is discussed more fully below, North Carolina's 
maintenance plan includes all the necessary components and is 
approvable as part of the redesignation request.
b. Attainment Emissions Inventory
    North Carolina selected 2005 as ``the attainment year'' for the 
Triangle Area for the purposes of demonstrating attainment of the 8-
hour ozone NAAQS. This attainment inventory identifies the level of 
emissions in the area, which is sufficient to attain the 8-hour ozone 
standard. North Carolina began development of this attainment inventory 
by first developing a baseline emissions inventory for the Triangle 
Area. The year 2005 was chosen as the base year for developing a 
comprehensive ozone precursor emissions inventory for which projected 
emissions could be developed for 2008, 2011, 2014, and 2017. Nonroad 
mobile emissions estimates were based on the EPA's NONROAD2005c model. 
On-road mobile source emissions were calculated using EPA's MOBILE6.2 
emission factors model. The 2005 VOC and NOX emissions, as 
well as the emissions for other years, for the Triangle Area were 
developed consistent with EPA guidance, and are summarized in Tables 4 
and 5 in the following subsection.
c. Maintenance Demonstration
    The June 7, 2007, final submittal includes a maintenance plan for 
the Triangle Area. This demonstration:
    (i) Shows compliance and maintenance of the 8-hour ozone standard 
by providing information to support the demonstration that current and 
future emissions of VOC and NOX remain at or below 
attainment year 2005 emissions levels. The year 2005 was chosen as the 
attainment year because it is one of the most recent three years (i.e., 
2004, 2005, and 2006) for which the Triangle Area has clean air quality 
data for the 8-hour ozone standard.
    (ii) Uses 2005 as the attainment year and includes future emission 
inventory projections for 2008, 2011, 2014, and 2017.
    (iii) Identifies an ``out year,'' at least 10 years after the time 
necessary for EPA to review and approve the maintenance plan. Per 40 
CFR part 93, subarea NOX MVEBs were established for the last 
year (2017) of the maintenance plan. Additionally, North Carolina 
chose, through interagency consultation, to establish subarea MVEBs for 
the year 2008 for NOX, and to determine insignificance for 
VOC for

[[Page 56320]]

the Triangle Area. See, section VII below.
    (iv) Provides the following actual and projected emissions 
inventories, in tons per day (tpd) for the Triangle Area. See, Tables 4 
and 5.

                                    Table 4.--Triangle Area Emissions of VOC
                                                 [Tons per day]
----------------------------------------------------------------------------------------------------------------
                        Source category                           2005      2008      2011      2014      2017
----------------------------------------------------------------------------------------------------------------
Point.........................................................     12.28     13.24     14.45     15.61     16.94
Area..........................................................     67.26     72.94     78.01     82.80     87.80
Mobile *......................................................     47.47     39.71     35.13     30.24     27.18
Nonroad **....................................................     30.78     26.24     23.99     23.28     23.01
                                                               -------------------------------------------------
    Total.....................................................    157.79    152.13    151.58    151.93    154.93
                                                               =================================================
Safety Margin.................................................       N/A      5.66      6.21      5.86     2.86
----------------------------------------------------------------------------------------------------------------
* Calculated using MOBILE 6.2.
** Calculated using NONROAD2005c.


                                      Table 5.--Triangle Area NOX Emissions
                                                 [tons per day]
----------------------------------------------------------------------------------------------------------------
                        Source category                           2005      2008      2011      2014      2017
----------------------------------------------------------------------------------------------------------------
Point.........................................................     38.37     33.55     34.50     35.43     35.04
Area..........................................................     13.02     13.65     14.24     14.87     15.55
Mobile *......................................................    101.68     81.66     59.00     42.78     32.59
Nonroad **....................................................     38.42     34.90     31.09     26.52     22.25
                                                               -------------------------------------------------
    Total.....................................................    191.49    163.76    138.83    119.60    105.43
                                                               =================================================
Safety Margin.................................................       N/A     27.73     52.66     71.89    86.06
----------------------------------------------------------------------------------------------------------------
* Calculated using MOBILE 6.2.
** Calculated using NONROAD2005c.

    A safety margin is the difference between the attainment level of 
emissions (from all sources) and the projected level of emissions (from 
all sources) in the maintenance plan. The attainment level of emissions 
is the level of emissions during one of the years in which the area met 
the NAAQS. North Carolina has decided to allocate a portion of the 
available safety margin to the subarea NOX MVEBs for the 
years 2008 and 2017 for the Triangle Area, and has calculated the 
safety margin in its submittal. See, Tables 4 and 5, above. This 
allocation and the resulting available safety margin for the Triangle 
Area are discussed further in section VII of this proposed rulemaking.
d. Monitoring Network
    There are currently eight monitors measuring ozone in the Triangle 
Area. North Carolina has committed in the maintenance plan to continue 
operation of these monitors in compliance with 40 CFR part 58, and has 
addressed the requirement for monitoring.
e. Verification of Continued Attainment
    North Carolina has the legal authority to enforce and implement the 
requirements of the ozone maintenance plan for the Triangle Area. This 
includes the authority to adopt, implement and enforce any subsequent 
emissions control contingency measures determined to be necessary to 
correct future ozone attainment problems.
    North Carolina will track the progress of the maintenance plan by 
performing future reviews of actual emissions for the Area using the 
latest emissions factors, models and methodologies. For these periodic 
inventories, North Carolina will review the assumptions made for the 
purpose of the maintenance demonstration concerning projected growth of 
activity levels. If any of these assumptions appear to have changed 
substantially, North Carolina will re-project emissions.
f. Contingency Plan
    The contingency plan provisions are designed to promptly correct a 
violation of the NAAQS that occurs after redesignation. Section 175A of 
the CAA requires that a maintenance plan include such contingency 
measures as EPA deems necessary to assure that the state will promptly 
correct a violation of the NAAQS that occurs after redesignation. The 
maintenance plan should identify the contingency measures to be 
adopted, a schedule and procedure for adoption and implementation, and 
a time limit for action by the state. A state should also identify 
specific indicators to be used to determine when the contingency 
measures need to be implemented. The maintenance plan must include a 
requirement that a state will implement all measures with respect to 
control of the pollutant that were contained in the SIP before 
redesignation of the area to attainment in accordance with section 
175A(d).
    In the June 7, 2007, submittal, North Carolina affirms that all 
programs instituted by the State and EPA will remain enforceable, and 
that sources are prohibited from reducing emissions controls following 
the redesignation of the area. The contingency plan included in the 
submittal provides tracking and triggering mechanisms to determine when 
contingency measures are needed and a process of developing and 
adopting appropriate control measures. The primary trigger of the 
contingency plan will be a violation of the 8-hour ozone NAAQS, or when 
the three-year average of the fourth-highest value is equal to or 
greater than 0.085 ppm at any of the Triangle Area monitors. The 
trigger date will be 60 days from the date that the State observes a 
fourth-highest value that, when averaged with the two previous ozone 
seasons' fourth highest values, would result in a three-year average 
equal to or greater than

[[Page 56321]]

0.085 ppm. The secondary trigger will apply where no actual violation 
of the 8-hour ozone standard has occurred, but where the State finds 
monitored ozone levels indicating that an ozone NAAQS violation may be 
imminent. An imminent violation exists where there is a pattern. A 
pattern will be deemed to exist when there are two consecutive ozone 
seasons in which the fourth-highest values are 0.085 ppm or greater at 
a single monitor within the Triangle Area. The trigger date will be 60 
days from the date that the State observes a fourth-highest value of 
0.085 ppm or greater at a monitor for which the previous season had a 
fourth-highest value of 0.085 ppm or greater. Similarly, the tertiary 
trigger is a first alert to a potential air