
[Federal Register Volume 77, Number 70 (Wednesday, April 11, 2012)]
[Proposed Rules]
[Pages 21690-21702]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-8729]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2012-0253; FRL-9658-6]


Approval and Promulgation of Air Quality Implementation Plan for 
1997 8-Hour Ozone Standard; Arizona

AGENCY: U.S. Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA is proposing to approve revisions to the Arizona state 
implementation plan (SIP) that demonstrate attainment of the 1997 8-
hour ozone national ambient air quality standards in the Phoenix-Mesa 
nonattainment area by June 15, 2009. These SIP revisions are the 2007 
Ozone Plan developed by the Maricopa Association of Governments and 
adopted and submitted to EPA by the Arizona Department of Environmental 
Quality on June 13, 2007. EPA is proposing to approve the 2007 Ozone 
Plan based on our determination that the plan contains all the 
provisions required for areas classified as nonattainment under Part D, 
Subpart 1 of the Clean Air Act, including the demonstration of 
reasonably available control measures (RACM), reasonable further 
progress (RFP), emission inventories, transportation conformity motor 
vehicle emission budgets for 2008, and contingency measures to be

[[Page 21691]]

implemented if the Phoenix-Mesa nonattainment area fails to attain by 
June 15, 2009.

DATES: Written comments must be received on or before May 11, 2012.

ADDRESSES: Submit comments, identified by docket number EPA-R09-OAR-
2012-0253, by one of the following methods:
     Federal e-Rulemaking Portal: www.regulations.gov. Follow 
the on-line instructions.
     Email: lee.anita@epa.gov.
     Mail or deliver: Marty Robin, Office of Air Planning (AIR-
2), U.S. Environmental Protection Agency Region IX, 75 Hawthorne 
Street, San Francisco, CA 94105.
    Instructions: All comments 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 Confidential Business Information (CBI) or 
other information whose disclosure is restricted by statute. 
Information that you consider CBI or otherwise protected should be 
clearly identified as such and should not be submitted through 
www.regulations.gov or email. The www.regulations.gov Web site is an 
``anonymous access'' system, and EPA will not know your identity or 
contact information unless you provide it in the body of your comment. 
If you send email directly to EPA, your email address will be 
automatically captured and included as part of the public comment. If 
EPA cannot read your comments due to technical difficulties and cannot 
contact you for clarification, EPA may not be able to consider your 
comment.
    Docket: The index to the docket for this action is available 
electronically on the www.regulations.gov Web site and in hard copy at 
EPA Region IX, 75 Hawthorne Street, San Francisco, California 94105. 
While all documents in the docket are listed in the index, some 
documents may be publicly available only at the hard copy location 
(e.g., copyrighted material), and some may not be publicly available at 
either location (e.g., CBI). To inspect the hard copy materials, please 
schedule an appointment during normal business hours with the contact 
listed in the FOR FURTHER INFORMATION CONTACT section below. Copies of 
the SIP materials are also available for inspection at the following 
location:
     Arizona Department of Environmental Quality, 1110 W. 
Washington Street, First Floor, Phoenix, AZ 85007, Phone: (602) 771-
2217.
    The SIP materials are also electronically available at: http://www.azmag.gov/Projects/Project.asp?CMSID2=1120.

FOR FURTHER INFORMATION CONTACT: Anita Lee, Air Planning Office (AIR-
2), U.S. Environmental Protection Agency, Region IX, (415) 972-3958, 
lee.anita@epa.gov.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. The 1997 8-Hour Ozone Standard and the Phoenix-Mesa Ozone 
Nonattainment Area
    A. Background on the 1997 8-Hour Ozone NAAQS
    B. The Phoenix-Mesa 8-Hour Ozone Nonattainment Area
II. CAA and Regulatory Requirements for 1997 8-Hour Ozone 
Nonattainment Area SIPs
III. Arizona's State Implementation Plan Submittal To Address Ozone 
Attainment in the Phoenix-Mesa Nonattainment Area
    A. Arizona's SIP Submittal
    B. CAA Procedural and Administrative Requirements for SIP 
Submittals
IV. Review of the 2007 Ozone Plan for Phoenix-Mesa
    A. Emission Inventories
    B. Reasonably Available Control Measures Demonstration and 
Control Strategy
    C. Attainment Demonstration
    D. Reasonable Further Progress Demonstration
    E. Contingency Measures
    F. Motor Vehicle Emissions Budgets for Transportation Conformity
V. EPA's Proposed Action
VI. Statutory and Executive Order Reviews

    Throughout this document, ``we'', ``us'' and ``our'' refer to EPA.

I. The 1997 8-Hour Ozone Standard and the Phoenix-Mesa Ozone 
Nonattainment Area

A. Background on the 1997 8-Hour Ozone NAAQS

    Ground-level ozone pollution is formed in the atmosphere from the 
reaction of volatile organic compounds (VOC) and oxides of nitrogen 
(NOX) in the presence of sunlight. These two pollutants, 
referred to as ozone precursors, are emitted by many types of pollution 
sources including on- and off-road motor vehicles and engines, power 
plants and industrial facilities, and smaller area sources such as lawn 
and garden equipment and paints.
    Scientific evidence indicates that adverse public health effects 
occur following exposure to ozone, particularly in children and adults 
with lung disease. Breathing air containing ozone can reduce lung 
function and inflame airways, which can increase respiratory symptoms 
and aggravate asthma or other lung diseases. Ozone exposure also has 
been associated with increased susceptibility to respiratory 
infections, medication use, doctor visits, and emergency department 
visits and hospital admissions for individuals with lung disease. Ozone 
exposure also increases the risk of premature death from heart or lung 
disease. Children are at increased risk from exposure to ozone because 
their lungs are still developing and they are more likely to be active 
outdoors, which increases exposure. See ``Fact Sheet, Proposal to 
Revise the National Ambient Air Quality Standards for Ozone'', January 
6, 2010 and 75 FR 2938 (January 19, 2010).
    On July 18, 1997, EPA revised the primary and secondary national 
ambient air quality standards (NAAQS or standard) for ozone to replace 
the existing 1-hour ozone standard of 0.12 parts per million (ppm) with 
an 8-hour standard of 0.08 ppm \1\ (62 FR 33856). EPA revised the ozone 
standard after considering substantial evidence from numerous health 
studies demonstrating that serious health effects are associated with 
exposures to ozone concentrations above the levels of these revised 
standards.
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    \1\ In March 2008, EPA completed another review of the primary 
and secondary ozone standards and further tightened the standards by 
lowering the level for both to 0.075 ppm (73 FR 16436, Mar. 27, 
2008).
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B. The Phoenix-Mesa 8-Hour Ozone Nonattainment Area

    Following promulgation of a new or revised NAAQS, EPA is required 
by Clean Air Act (CAA) section 107(d) to designate areas throughout the 
nation as attaining or not attaining the NAAQS. Under the 
implementation rule for the 1997 8-hour ozone standard, EPA designated 
certain areas as nonattainment under title I, part D, subpart 1 of the 
CAA (subpart 1) if the area's 1-hour ozone design value was above the 
level of the standard but below 0.121 ppm. On April 15, 2004, EPA 
designated Phoenix-Mesa as ``Subpart 1'' nonattainment for the 1997 8-
hour ozone standard under CAA section 172. See 69 FR 23858 (April 30, 
2004) and 40 CFR 81.303. The designation became effective on June 15, 
2004. Under part D, subpart 1 of the Act, states must submit plans to 
come into attainment within 3 years of the effective date of the 
nonattainment designation, and must attain the standard as 
expeditiously as practicable, but no later than 5 years after the 
effective date of the designation. Arizona Department of Environmental 
Quality (ADEQ) submitted the 2007 Attainment Plan to EPA on June 13,

[[Page 21692]]

2007 \2\ to attain the 1997 8-hour ozone standard by the attainment 
date of June 15, 2009, which is 5 years after the effective date of the 
area's designation as nonattainment.\3\
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    \2\ Letter from Stephen A. Owens, Director, Arizona Department 
of Environmental Quality to Wayne Nastri, Regional Administrator, 
U.S. Environmental Protection Agency, Region IX, dated June 13, 
2007, plus three enclosures, including the ``Eight-Hour Ozone Plan 
for the Maricopa Nonattainment Area, dated June 2007'' and 
Appendices Volumes one and two, dated June 2007.
    \3\ On March 23, 2009, ADEQ submitted to EPA a redesignation 
request and maintenance plan for Phoenix-Mesa for the 1997 8-hour 
ozone standard based on ambient ozone monitoring data for the 2006-
2008 period. EPA has not yet acted on this submittal. The 
maintenance plan and redesignation request are available from the 
Maricopa Association of Governments at: http://www.azmag.gov/Projects/Project.asp?CMSID2=1120&MID=Environmental%20Programs.
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    In June 2007, the United States Court of Appeals for the District 
of Columbia Circuit (D.C. Circuit Court) vacated the portion of the 
2004 ozone implementation rule that allowed areas to be classified 
under subpart 1. See South Coast Air Quality Mgmt. Dist. v. EPA, 472 F. 
3d 882 (D.C. Cir. 2006), reh'g denied 489 F.3d 1245 (SCAQMD) (vacating 
certain elements of EPA's Phase 1 ozone implementation rule). On 
January 16, 2009 (74 FR 2936), EPA published a proposed rule to 
address, among other issues, the DC Circuit Court vacatur of the 
classification system that EPA used to designate a subset of initial 
1997 8-hour ozone nonattainment areas under subpart 1. In that 
rulemaking, EPA proposed that all areas designated nonattainment for 
the 1997 8-hour ozone NAAQS under subpart 1 would be classified as 
subpart 2 areas (hereafter referred to as the Subpart 1/Subpart 2 
Rulemaking). The Phoenix-Mesa area is included in the areas that would 
be classified under subpart 2 if EPA's proposal is finalized. EPA has 
not yet taken final action on the Subpart 1/Subpart 2 Rulemaking. 
Following completion of the Subpart 1/Subpart 2 Rulemaking, EPA will 
address in a future rulemaking any additional requirements that become 
applicable to Phoenix-Mesa, if any, as a result of its classification 
under subpart 2. If, after Phoenix-Mesa is classified under subpart 2, 
EPA determines in a future rulemaking that the area is in attainment 
with the 1997 8-hour ozone standard, then the obligation to submit 
certain planning SIPs related to attainment of the 1997 8-hour ozone 
standard pursuant to its subpart 2 classification would be suspended in 
accordance with 40 CFR 51.918.
    The Phoenix-Mesa nonattainment area is located in the central 
portion of Arizona and encompasses 4,880 square miles, including the 
urban portions of Maricopa and Pinal Counties, the Fort McDowell 
Yavapai Nation and the Salt River-Pima Maricopa Indian Community. For a 
precise description of the geographic boundaries of the Phoenix-Mesa 
nonattainment area, see 40 CFR 81.303. The Maricopa Association of 
Governments (MAG) is the agency with primary responsibility for 
developing the plan to attain the 1997 8-hour ozone standard for 
Phoenix-Mesa.
    Ambient 8-hour ozone concentrations in Phoenix-Mesa vary depending 
on location and season, with the highest values generally occurring in 
May-September, in north Phoenix or the air quality monitors located in 
the mountainous northeastern region of the Phoenix-Mesa nonattainment 
area. Ozone design values \4\ from Phoenix-Mesa that exceeded the 1997 
8-hour standard of 0.08 parts per million \5\ (ppm) ranged from 0.085 
ppm (for the 2000-2002, 2001-2003, and 2003-2005 periods) to 0.088 ppm 
(for the 1998-2000 and 1999-2001 periods). The ozone design values for 
the Phoenix-Mesa nonattainment area for the 2004-2006 period (highest 
design value was 0.083 ppm) and years thereafter were at or below the 
standard. See EPA Air Quality System (AQS) data available in the docket 
for this proposed rulemaking and Table 3 below.
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    \4\ A design value is an ambient concentration calculated using 
a specific methodology to evaluate monitored air quality data and is 
used to determine whether an area's air quality meets a NAAQS. The 
methodology for calculating design values for the 8-hour ozone NAAQS 
is found in 40 CFR part 50, Appendix I.
    \5\ Based on the rounding conventions described in 40 CFR part 
50, Appendix I, a design value of 0.085 ppm is the lowest value that 
exceeds the 1997 8-hour ozone NAAQS of 0.08 ppm.
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II. CAA and Regulatory Requirements for 1997 8-Hour Ozone Nonattainment 
Area SIPs

    Each area designated nonattainment for the 1997 8-hour ozone 
standard is subject to, at minimum, the general requirements for 
nonattainment area plans in subpart 1 of part D, title I of the CAA. 
Subpart 2 of part D contains more detailed requirements for ozone 
nonattainment areas classified under this subpart. The Phoenix-Mesa 
ozone nonattainment area is not currently classified under subpart 
2.\6\ EPA has proposed to classify the Phoenix-Mesa area under subpart 
2 as ``marginal'' nonattainment for the 1997 8-hour ozone NAAQS (see 74 
FR 2936 at 2944, January 16, 2009) but has not yet completed this 
rulemaking. Although a future final decision by EPA to classify the 
Phoenix-Mesa area under subpart 2 may trigger additional future 
requirements for the area, EPA believes that this does not prevent EPA 
from proposing or ultimately finalizing our action on the 2007 Ozone 
Plan in accordance with the subpart 1 requirements that currently apply 
to the area.\7\ Thus, for purposes of evaluating the 2007 Ozone Plan, 
we are reviewing it for consistency with the applicable requirements of 
part D, title I of the Act, which are contained in sections 172(c)(1)-
(9).\8\
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    \6\ EPA now refers to these areas as ``former subpart 1'' 
nonattainment areas in light of the SCAQMD decision.
    \7\ EPA is currently obligated under the terms of a Consent 
Decree to take final action on the 2007 Ozone Plan by May 31, 2012. 
See WildEarth Guardians v. Jackson, Case No. 4:11-cv-02205-SI (N.D. 
CA).
    \8\ Although the DC Circuit Court in SCAQMD rejected EPA's 
rationale for implementing the 1997 8-hour ozone standard in certain 
nonattainment areas solely under subpart 1, EPA does not believe 
that the Court's ruling in this case alters any subpart 1 
requirements that currently apply to the 2007 Ozone Plan.
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    In order to assist states in developing effective plans to attain 
the ozone standard, EPA issued the 8-hour ozone implementation rule. 
This rule was finalized in two phases. The first phase of the rule 
addresses classifications for the 1997 8-hour ozone standard, 
applicable attainment dates for the various classifications, and the 
timing of emissions reductions needed for attainment. See 69 FR 23951 
(April 30, 2004). The second phase addresses SIP submittal dates and 
the requirements for reasonably available control technology and 
measures (RACT and RACM), reasonable further progress (RFP) 
demonstration, modeling and attainment demonstrations, contingency 
measures, and new source review. See 70 FR 71612 (November 29, 2005). 
The rule is codified at 40 CFR part 51, subpart X.\9\ We discuss each 
of the applicable CAA and regulatory requirements for 8-hour ozone 
nonattainment plans in more detail below.
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    \9\ EPA has revised or proposed to revise several elements of 
the 8-hour ozone implementation rule since its initial promulgation 
in 2004. See, e.g., 74 FR 2936 (January 16, 2009); 75 FR 51960 
(August 24, 2010); and 75 FR 80420 (December 22, 2010). None of 
these revisions affect any provision of the rule that is applicable 
to our proposed action today on the Phoenix-Mesa 2007 8-hour Ozone 
SIP.
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III. Arizona's State Implementation Plan Submittal To Address Ozone 
Attainment in the Phoenix-Mesa Nonattainment Area

A. Arizona's SIP Submittal

    On June 13, 2007, the Arizona Department of Environmental Quality 
(ADEQ) submitted the ``Eight-Hour

[[Page 21693]]

Ozone Plan for the Maricopa Nonattainment Area'' (2007 Ozone Plan) to 
EPA as a revision to the Arizona SIP. The plan was deemed complete by 
operation of law on December 13, 2007. MAG developed the 2007 Ozone 
Plan and the MAG Regional Council Executive Committee adopted the plan 
on June 11, 2007. ADEQ adopted the plan on June 13, 2007.\10\ The 2007 
Ozone Plan contains complete emission inventories for ozone precursors 
for 2002 and 2008, photochemical modeling to demonstrate that the 
standard will be attained in 2008 through the continued implementation 
of federal, state, and local control measures, motor vehicle emission 
budgets (MVEBs) used for transportation conformity, and descriptions of 
the State's compliance with CAA requirements for ``Subpart 1'' ozone 
nonattainment areas. We are proposing to approve the 2007 Ozone Plan 
for the Phoenix-Mesa nonattainment area.
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    \10\ Letter from Stephen A. Owens, Director of Arizona 
Department of Environmental Quality, to Wayne Nastri, Regional 
Administrator, U.S. Environmental Protection Agency, Region IX, 
``Submittal of the Eight-Hour Ozone Plan for the Maricopa County 
Nonattainment Area''. June 13, 2007.
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B. CAA Procedural and Administrative Requirements for SIP Submittals

    CAA sections 110(a)(1) and (2) and 110(l) require a state to 
provide reasonable public notice and opportunity for public hearing 
prior to the adoption and submittal of a SIP or SIP revision. To meet 
this requirement, every SIP submittal should include evidence that 
adequate public notice was given and an opportunity for a public 
hearing was provided consistent with EPA's implementing regulations in 
40 CFR 51.102.
    MAG has satisfied the applicable statutory and regulatory 
requirements for reasonable public notice and hearing prior to adoption 
and submittal of the 2007 Ozone Plan. MAG and ADEQ jointly held two 
public hearings on June 1, 2007 and June 4, 2007. As evidence of 
notification of public hearings consistent with 40 CFR 51.102, the SIP 
submittal includes proof of newspaper publication and copies of letters 
sent to EPA and affected federal, state, and local agencies notifying 
interested parties of the joint MAG and ADEQ public hearings. We find, 
therefore, that the 2007 Ozone Plan submittal meets the procedural 
requirements for public notice and hearing in sections 110(a) and 
110(l) of the CAA.
    CAA section 110(k)(1)(B) requires EPA to determine whether a SIP 
submittal is complete within 60 days of receipt. This section also 
provides that any plan submittal that EPA has not affirmatively 
determined to be complete or incomplete will be deemed complete by 
operation of law six months after the date of submittal. EPA's SIP 
completeness criteria are found in 40 CFR part 51, Appendix V. The 2007 
Ozone Plan, submitted by ADEQ on June 13, 2007, was deemed complete by 
operation of law on December 13, 2007.

IV. Review of the 2007 Ozone Plan for Phoenix-Mesa

    EPA evaluated the 2007 Ozone Plan according to the general subpart 
1 nonattainment plan requirements contained in section 172(c) of the 
Act.

A. Emission Inventories

1. Requirements for Emissions Inventories
    CAA section 172(c)(3) requires each state with an ozone 
nonattainment area to submit plan provisions that include a 
``comprehensive, accurate, current inventory of actual emissions from 
all sources of the relevant pollutant or pollutants in such area, 
including such periodic revisions as the Administrator may determine 
necessary to assure that the requirements of this part are met''. EPA 
has issued the ``Emissions Inventory Guidance for Implementation of 
Ozone and Particulate Matter National Ambient Air Quality Standards 
(NAAQS) and Regional Haze Regulations'' (EI Guidance),\11\ which 
provides guidance on how to develop base year and future year baseline 
emission inventories for 8-hour ozone, PM2.5, and regional 
haze SIPs. For areas designated nonattainment for the 8-hour ozone 
standard in 2004, EPA recommends using calendar year 2002 as the base 
year for the inventory. EI Guidance, p. 8.
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    \11\ ``Emissions Inventory Guidance for Implementation of Ozone 
and Particulate Matter National Ambient Air Quality Standards 
(NAAQS) and Regional Haze Regulations'', EPA-454/R-05-001, November 
2005. This document is available at: http://www.epa.gov/ttnchie1/eidocs/eiguid/index.html.
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    Emissions inventories for ozone should include emissions of VOC, 
NOX and carbon monoxide (CO) and represent an average summer 
week day during the ozone season. See EI Guidance, pp. 14 and 17. 
States should include documentation in their submittals explaining how 
the emissions data were calculated. See 70 FR 71612 (Nov. 29, 2005) and 
EI Guidance p. 40. In estimating mobile source emissions, states should 
use the latest emissions models and planning assumptions available at 
the time the SIP is developed. See 68 FR 32802 (June 2, 2003) and 70 FR 
71612 (Nov. 29, 2005).
2. Emission Inventories in the 2007 8-Hour Ozone Plan
    The base year and future year baseline inventories for 
NOX, CO and VOC for the Phoenix-Mesa nonattainment area, 
together with additional documentation for the inventories, are found 
in Volume 1 of the Appendices to the 2007 Ozone Plan.\12\ These 
inventories represent average summer day (ozone season) emissions. A 
base year inventory is provided for 2002 and the projected baseline 
inventory is provided for the attainment year of 2008.\13\ All 
inventories include NOX, CO, and VOC emissions from point, 
area, nonroad mobile, and onroad mobile sources, except that biogenic 
emission inventories include only NOX and VOC emissions.
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    \12\ By ``future year baseline inventories'' or ``projected 
baseline inventories'', we mean projected emission inventories for 
future years that account for, among other things, the ongoing 
effects of economic growth and adopted emission control 
requirements.
    \13\ EPA's ozone implementation rule defines ``attainment year 
ozone season'' as ``the ozone season immediately preceding a 
nonattainment area's attainment date.'' 40 CFR 51.900(g). Because 
the attainment date for Phoenix-Mesa is June 15, 2009, we refer to 
2008 as the attainment year, and the 2008 ozone season as the 
``attainment year ozone season.''
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    The 2002 Periodic Emission Inventory (PEI) emissions estimates for 
Maricopa County and the Phoenix-Mesa nonattainment area, which provided 
the basis for the 2002 base year inventory, were calculated in terms of 
annual emissions and ozone season-day emissions. Emissions from point 
sources were estimated from each identified facility through permit 
system databases and annual emission reports submitted to the 
facility's permitting authority. Emissions from area sources were 
estimated by source category using information from permit databases 
and previous SIP inventories. Nonroad mobile source emissions were 
estimated with the EPA NONROAD 2002 model and onroad mobile source 
emissions were estimated from emission factors for various vehicle 
classes from MOBILE6.2 combined with estimates of vehicle miles 
traveled (VMT) using data submitted by the Arizona Department of 
Transportation to the U.S. Department of Transportation's Federal 
Highway Administration for the 2002 Highway Performance and Monitoring 
System. Biogenic emissions of NOX and VOC were calculated 
using MAGBEIS2, a modified version of the UAM-BEIS2 model developed 
specifically for use in Maricopa County, based on land use

[[Page 21694]]

information, surface temperature data, and emission factors for land 
use categories. See 2002 Periodic Emissions Inventory for Ozone 
Precursors, June 2004 in Volume 1 of the Appendices to the 2007 Ozone 
Plan.
    Ozone precursor emissions from point, area, onroad, and nonroad 
sources used in the modeling domain (Table 1) were developed from the 
Comprehensive Air Quality Model with Extensions (CAMx), version 4.40, 
and the Emissions Preprocessor System (EPS3.0), based on the 2002 
Periodic Emission Inventory for the three ozone episodes modeled for 
2002. Biogenic VOC emission estimates used for the 2002 modeling domain 
(e.g., 451.3 metric tons per day in the June 2002 ozone episode) are 
significantly higher than biogenic VOC emissions estimated in the 2002 
PEI (e.g., 41.7 metric tons per ozone season day). Section III of 
Appendix A, Exhibit 2 of the 2007 Ozone Plan describes the method used 
to estimate biogenic emissions for the modeling domain. MAG used a 
model developed in 2005, called Model of Emissions of Gases and 
Aerosols from Nature (MEGAN), that was determined to be more reliable 
and accurate for Maricopa County because it relies on local field 
studies that identified dominant plant species and emission factors, as 
well as locations and biomass densities, to estimate biogenic emissions 
of ozone precursors. In the 2002 base year inventory, biogenic sources 
contributed 65 percent to total VOC emissions. In contrast, 
anthropogenic onroad mobile sources dominated the total NOX 
emissions and accounted for 63 percent of total NOX. See 
Tables 5-3 and 5-4 of the 2007 Ozone Plan.
    The 2002 inventory was projected to 2008 by accounting for expected 
growth factors, ongoing control programs, and retirement rates for 
obsolete sources of emissions. MAG accounted for known projects in 2008 
(e.g., the Phoenix Expansion Project of the Transwestern Pipeline 
Company) and additionally applied a five percent increase to onroad 
mobile source emissions of NOX and a three percent increase 
to all other anthropogenic emissions of VOC and NOX. The 
three percent increase was based on population projections prepared by 
the Arizona Department of Economic Security, based on a 2005 special 
census in Maricopa County. MAG applied the five percent increase to 
onroad mobile source emissions of NOX to create a safety 
margin for transportation conformity. See 2007 Ozone Plan, p. 5-5, and 
Appendices to Ozone Plan, Volume 1.
    For biogenic emissions, the 2002 inventory was held constant for 
2008. In additional information provided to EPA, MAG explained that no 
projected land use or land cover data was available for the 2008 
attainment year, therefore biogenic emissions in the ozone modeling 
domain were held constant.\14\ In the approved 1-hour ozone maintenance 
plan, MAG projected an increase in VOC emissions from the Phoenix 
Metropolitan nonattainment area due to changes in land use, i.e., 
increasing urbanization and residential land use and decreasing use of 
land for agriculture. See 70 FR 13425 (Mar. 21, 2005). The 1-hour ozone 
maintenance plan relied on MAGBEIS2 to estimate biogenic emissions from 
the nonattainment area and modeling domain.\15\ As shown in the 
additional information provided by MAG on February 8, 2012, the 
MAGBEIS2 VOC emission factor for urbanized land use is greater than the 
VOC emission factor for agricultural land use, therefore, based on the 
projected increased urbanization in the 1-hour ozone nonattainment 
area, VOC emissions projected by MAGBEIS2 increased from the 1999 base 
year to the 2015 maintenance year. In contrast, as described above, the 
2007 8-hour ozone plan relied on a new biogenic emissions model (MEGAN) 
that is more representative of Maricopa County and its desert 
environment. The additional information provided by MAG shows the 
urbanized land use emission factors from MEGAN are lower than emission 
factors associated with agriculture or other undeveloped desert 
landscapes in Maricopa County. Therefore, using MEGAN, MAG expects that 
the trend of increasing urbanization (as projected in the 1-hour ozone 
maintenance plan) is expected to decrease VOC emissions from Maricopa 
County. Because MAG did not have 2008 land use data available, it 
determined that maintaining constant biogenic emissions of the ozone 
precursors would be more conservative than attempting to estimate the 
anticipated decrease in biogenic VOC emissions.\16\
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    \14\ Email from Cathy Arthur, MAG, to Anita Lee, EPA, re: 
``Biogenic VOCs'' on February 8, 2012, plus two attachments on land 
use boundaries and emission factors.
    \15\ Ibid.
    \16\ Ibid.

 Table 1--Emission Inventories for the Phoenix-Mesa Modeling Domain for
                           June Ozone Episode
                          [Metric tons per day]
------------------------------------------------------------------------
                                       NOX                   VOC
                             -------------------------------------------
                                 2002       2008       2002       2008
------------------------------------------------------------------------
Point.......................      11.15      32.78      11.72      13.55
Area........................       9.79      13.49      90.56     105.03
Nonroad Mobile..............      79.97      86.58      50.73      57.55
Onroad Mobile...............     182.36     145.52      91.84      72.34
Biogenics...................       8.56       8.56     451.28     451.28
                             -------------------------------------------
    Total...................     291.82     286.93     696.13     699.75
------------------------------------------------------------------------
Source: 2007 Ozone Plan at Tables 5-3 and 5-4.

3. Proposed Action on the Emission Inventories
    We have reviewed the 2002 base year inventory and the inventory 
methodologies used in the 2007 Ozone Plan and believe that the 
inventory was developed consistent with the CAA requirements as 
reflected in the 8-hour ozone implementation rule and EPA's guidance. 
The 2002 base year inventory is a comprehensive inventory of actual 
emissions of ozone precursors in the Phoenix-Mesa nonattainment area. 
We therefore propose to approve the base year inventory as meeting the 
requirements of CAA section 172(c)(3) and EPA's 8-hour ozone 
implementation rule.

[[Page 21695]]

B. Reasonably Available Control Measures Demonstration and Control 
Strategy

1. Requirements for RACM and Control Strategies
    CAA Section 172(c)(1) requires that each attainment plan ``provide 
for the implementation of all reasonably available control measures as 
expeditiously as practicable (including such reductions in emissions 
from existing sources in the area as may be obtained through the 
adoption, at a minimum, of reasonable available control technology), 
and shall provide for attainment of the national primary ambient air 
quality standards.'' The 8-hour ozone implementation rule requires that 
for each nonattainment area that is required to submit an attainment 
demonstration, the state must also submit concurrently a SIP revision 
demonstrating that it has adopted all RACM necessary to demonstrate 
attainment as expeditiously as practicable and to meet any RFP 
requirements. 40 CFR 51.912(d).
    EPA has previously provided guidance interpreting the RACM 
requirement in the General Preamble at 13560 \17\ and in a memorandum 
entitled ``Guidance on the Reasonably Available Control Measure 
Requirement and Attainment Demonstration Submissions for Ozone 
Nonattainment Areas'', John Seitz, Director, OAQPS to Regional Air 
Directors, November 30, 1999 (Seitz memo). In summary, EPA guidance 
provides that, to address the requirement to adopt all RACM, states 
should consider all potentially reasonable control measures for source 
categories in the nonattainment area to determine whether they are 
reasonably available for implementation in that area and whether they 
would, if implemented individually or collectively, advance the area's 
attainment date by one year or more. See Seitz memo and General 
Preamble at 13560.\18\ Any measures that are necessary to meet these 
requirements that are not already either federally promulgated, part of 
the state's SIP, or otherwise creditable in SIPs must be submitted in 
enforceable form as part of a state's attainment plan for the area.
---------------------------------------------------------------------------

    \17\ The ``General Preamble for the Implementation of Title I of 
the Clean Air Act Amendments of 1990'', published at 57 FR 13498 on 
April 16, 1992, describes EPA's preliminary view on how we would 
interpret various SIP planning provisions in title I of the CAA as 
amended in 1990, including those planning provisions applicable to 
the 1-hour ozone standard. EPA continues to rely on certain guidance 
in the General Preamble to implement the 8-hour ozone standard under 
title I.
    \18\ See also ``State Implementation Plans; General Preamble for 
Proposed Rulemaking on Approval of Plan Revisions for Nonattainment 
Areas'', 44 FR 20372 (April 4, 1979), and Memorandum dated December 
14, 2000 from John S. Seitz, Director, Office of Air Quality 
Planning and Standards, ``Additional Submission on RACM from States 
with Severe One-Hour Ozone Nonattainment Area SIPs''.
---------------------------------------------------------------------------

    CAA section 172(c)(6) requires nonattainment plans to ``include 
enforceable emission limitation, and such other control measures, 
means, or techniques (including economic incentives such as fees, 
marketable permits, and actions of emission rights), as well as 
schedules and timetables for compliance, as may be necessary or 
appropriate to provide for attainment of such standard in such area by 
the applicable attainment date * * *.'' See also CAA section 
110(a)(2)(A). The ozone implementation rule requires that all control 
measures needed for attainment be implemented no later than the 
beginning of the attainment year ozone season. See 40 CFR 51.908(d). 
The attainment year ozone season is defined as the ozone season 
immediately preceding a nonattainment area's attainment date. See 40 
CFR 51.900(g).
2. RACM Demonstration and the Control Strategy in the 2007 Ozone Plan
    The attainment demonstration for the Phoenix-Mesa nonattainment 
area, which we discuss further in section IV.D of this document, shows 
that implementation of all of the measures identified as RACM for the 
1997 8-hour ozone NAAQS would enable the Phoenix-Mesa area to attain 
the 1997 8-hour ozone standard during the 2008 ozone season, preceding 
the 2009 attainment date for the area. EPA previously approved all of 
the key NOX and VOC control measures, including several 
dozen VOC RACT rules, as part of Arizona's plans for attaining and 
maintaining the 1-hour ozone standard in Phoenix-Mesa.\19\ The 2007 
Ozone Plan specifically relies on seven of these control measures to 
demonstrate attainment of the 1997 8-hour ozone standard by June 15, 
2009, and provides for implementation of these measures by the 
beginning of the attainment year ozone season (January 2008), 
consistent with the requirements of 40 CFR 51.908(d). See 2007 Ozone 
Plan at pp. 4-2 through 4-7.\20\ We discuss below the seven measures 
that the attainment demonstration in the 2007 Ozone Plan relied on to 
reduce emissions of VOC and/or NOX (see Table 2). Emission 
reductions associated with each measure were estimated for the June 
2008 ozone episode modeled for the attainment demonstration. Of these 
seven measures, phased-in emission test cutpoints and the development 
of intelligent transportation systems resulted in the greatest 
reduction in VOC emissions, and the summer fuel reformulation resulted 
in the greatest reduction in NOX emissions.
---------------------------------------------------------------------------

    \19\ See, e.g., 2007 Ozone Plan at Table 1-1; 68 FR 2912 
(January 22, 2003); 69 FR 10161 (March 4, 2004); 70 FR 30370 (May 
26, 2005); 70 FR 13425 (March 21, 2005) (proposed redesignation of 
Phoenix to attainment for the 1-hour standard) and 70 FR 34362 (June 
14, 2005) (final redesignation). RACT rules for NOX were 
not required for purposes of attaining and maintaining the 1-hour 
ozone NAAQS in Phoenix-Mesa because EPA approved a petition for 
NOX exemption for this purpose. 60 FR 19510 (April 19, 
1995).
    \20\ The 2007 Ozone Plan refers to these seven control measures 
as ``attainment measures,'' to be distinguished from ``baseline 
measures,'' which were taken into account in the base year and 
projection year emission inventories. See 2007 Ozone Plan at 4-2 and 
Volume 1 of the Appendices to the 2007 Ozone Plan at Table III-1.

                         Table 2--2008 Emission Reductions From ``Attainment Measures''
----------------------------------------------------------------------------------------------------------------
                                                               VOC                              NOX
                                                ----------------------------------------------------------------
                                                                     % Change                        % Change
                                                  Metric ton/day    compared to   Metric ton/day    compared to
                                                    reduction     2008 base case     reduction    2008 base case
----------------------------------------------------------------------------------------------------------------
Summer Fuel Reformulation......................        \1\ (0.1)        \1\ <0.1            10.3             3.5
Phased-in Emission Test Cutpoints..............             3.1              1.2             2.6             0.9
One Time Waiver from Vehicle Emissions Test....             0.1             <0.1            <0.1            <0.1
Coordinate Traffic Signal Systems..............            <0.1             <0.1            <0.1            <0.1
Develop Intelligent Transportation Systems.....             2.2              0.9             0.4             0.1
Tougher Enforcement of Vehicle Registration and             0.2             <0.1             0.1            <0.1
 Emission Test Compliance......................

[[Page 21696]]

 
Rule 358: Polystyrene Foam Operations..........             0.5              0.2             N/A             N/A
                                                ----------------------------------------------------------------
    Total......................................             6.0              2.4            13.4             4.6
----------------------------------------------------------------------------------------------------------------
Source: 2007 Ozone Plan at Table 5-2.
\1\ Increase.

a. Summer Fuel Reformulation
    The 2007 Ozone Plan relies on H.B. 2307, a Cleaner Burning Gasoline 
(CBG) program passed by the Arizona Legislature in 1997. The CBG 
program contains requirements related to seasonal changes in gasoline 
formulation related to vapor pressure and oxygen content. Typically, 
fuel reformulation measures are designed to reduce summertime 
evaporative VOC emissions. However, the results of MAG's emissions 
modeling analyses suggest that the summer reformulation measure would 
increase VOC emissions slightly and significantly reduce emissions of 
NOX. In Volume 2 of the Appendices to the 2007 Ozone Plan, 
in response to EPA comments, MAG explains that the slight increase in 
projected VOC emissions from the summer fuel reformulation measure 
occurred because the MOBILE6.2 input for the measure specified a Reid 
vapor pressure (RVP) of 7.0 pounds per square inch (psi). Actual fuel 
specifications for the 2002 base case used actual fuel specifications 
from the Arizona Department of Weights and Measures that were lower 
than 7.0 psi. The projected decrease in NOX emissions in 
2008 from the summer fuel reformulation measure is a result of the 
removal of the summertime (April 1 through November 1) minimum oxygen 
content standard for Type 1 gasoline. Oxygenates in fuel are used to 
improve combustion as a control strategy for CO and other products of 
incomplete combustion, for example unburned VOCs; however improved 
combustion also tends to increase formation of NOX. 
Therefore, removal of the minimum summertime oxygenate standard is 
projected to reduce formation of NOX. See 2007 Ozone Plan at 
4-2, 4-3.
b. Phased-in Emission Test Cutpoints
    The 2007 Ozone Plan describes two measures passed by the Arizona 
Legislature that comprise this attainment measure: H.B. 2237, passed in 
1997, that appropriates funds from the State General Fund to develop 
and implement an alternative test protocol to reduce false failure 
rates associated with the more stringent standards for the Vehicle 
Emissions Testing Program, and S.B. 1427, which requires vehicles in 
certain areas to be emission tested and requires owners of the newest 
five model year vehicles to be exempt from testing but to pay an in 
lieu fee that is deposited into the Arizona Clean Air Fund, effective 
December 31, 1998. Using MOBILE6.2, MAG estimated that this measure 
reduces NOX emissions by 2.6 metric tons per day in the June 
2008 ozone episode and VOC emissions by 3.1 metric tons per day. See 
2007 Ozone Plan at 4-3, 4-4.
c. One Time Waiver From Vehicle Emissions Test
    The Arizona Legislature passed S.B. 1002 which limits issuance of a 
waiver for failure to comply with emission testing requirements to one-
time only, effective January 1, 1997. MAG modeled this measure in 
MOBILE6.2 by adjusting the percentage of waivers allowed and estimated 
that this measure reduces NOX emissions by less than 0.1 
metric tons per day in the June 2008 ozone episode and VOC emissions by 
0.1 metric tons per day. See 2007 Ozone Plan at 4-4.
d. Coordinate Traffic Signal Systems
    House Bill 2237 passed by the Arizona Legislature contains 
appropriations for fiscal years 1997-1998 and 1998-1999 to Arizona 
Department of Transportation for distribution to cities and counties 
for synchronization of traffic signals within and across jurisdictional 
boundaries. MAG modeled this measure in MOBILE6.2 by adjusting the 
input for idling time at traffic signals and estimated that this 
measure reduces NOX emissions by less than 0.1 metric tons 
per day in the June 2008 ozone episode and VOC emissions by less than 
0.1 metric tons per day. See 2007 Ozone Plan at 4-4, 4-5.
e. Develop Intelligent Transportation Systems
    The 2007 Ozone Plan cites three committed control measures in the 
1-hour Ozone Maintenance Plan that serve to reduce traffic congestion: 
``Coordinate Traffic Signal Systems'', ``Develop Intelligent 
Transportation Systems'', and ``Reduce Traffic Congestion at Major 
Intersections''. The 2007 Ozone Plan describes these measures as 
technologies implemented on the local level over fiscal years 2003-2006 
that reduce VOC and NOX emissions by reducing congestion. 
MAG estimated emission reductions from these measures to be 0.4 metric 
tons of NOX per day in the June 2008 ozone episode and 2.2 
metric tons of VOC per day. See 2007 Ozone Plan at 4-5.
f. Tougher Enforcement of Vehicle Registration and Emission Test 
Compliance
    The 2007 Ozone Plan cites two measures from the Arizona Legislature 
and a program implemented by the Arizona Motor Vehicle Division of the 
Arizona Department of Transportation that collectively improve 
enforcement of vehicle registration and compliance with vehicle testing 
requirements: S.B. 1427 passed in 1998 that requires school and special 
districts in certain areas to prohibit employees who have not complied 
with emission testing requirements from parking in employee parking 
lots, and H.B. 2254 passed in 1999 that requires vehicles owned by 
federal, state, or political state subdivisions in Arizona to comply 
with A.R.S 49-542. MAG modeled this measure in MOBILE6.2 by adjusting 
the weighting between inspection and maintenance (I/M) and non-I/M 
emission factors, and estimated that this measure reduces 
NOX emissions by 0.1 metric tons per day in the June 2008 
ozone episode and VOC emissions by 0.2 metric tons per day. See 2007 
Ozone Plan at 4-5, 4-6.

[[Page 21697]]

g. Maricopa County Rule 358: Polystyrene Foam Operations
    Rule 358 adopted by Maricopa County on April 20, 2005 limits VOC 
emissions from the manufacturing of expanded-polystyrene products. MAG 
relied on information provided by the Maricopa County Air Quality 
Department that Rule 358 would result in 80 percent control 
effectiveness and 80 percent rule effectiveness. MAG estimated VOC 
emission reductions to be 0.5 metric tons per day in the June 2008 
ozone episode, with no effect on emissions of NOX. See 2007 
Ozone Plan at 4-6, 4-7.
3. Proposed Actions on the RACM Demonstration and Control Strategy
    Based on our review of the RACM analysis and Arizona's adopted 
rules, we propose to find that the 2007 Ozone Plan provides for 
implementation of all reasonably available control measures necessary 
to demonstrate expeditious attainment of the 1997 8-hour ozone standard 
and to meet any related RFP requirements in the Phoenix-Mesa 
nonattainment area, consistent with the applicable requirements of CAA 
section 172(c)(1) and 40 CFR 51.912.

C. Attainment Demonstration

1. Requirements for Attainment Demonstration
    CAA section 172(c)(1) requires states with ozone nonattainment 
areas to submit plan provisions that provide for attainment of the 
national ambient air quality standards. See also 40 CFR 51.908. The 
attainment demonstration should include:
    a. Technical analyses to locate and identify sources of emissions 
that are causing violations of the 8-hour ozone NAAQS within the 
nonattainment area;
    b. Adopted measures with schedules for implementation and other 
means and techniques necessary and appropriate for attainment; and
    c. Contingency measures required under section 172(c)(9) of the 
CAA.
    See 70 FR 71612 (Nov. 29, 2005).
    The requirements for the first two items are described in the 
sections on emission inventories and RACM/RACT above (sections IV.A and 
IV.B) and in the sections on air quality modeling and attainment 
demonstration that follow immediately below. Requirements for the third 
item are described in the section on contingency measures (IV.F.).
2. Air Quality Modeling in the Phoenix-Mesa 2007 Ozone Plan
    Under EPA's ozone implementation rule, an attainment demonstration 
must meet the air quality modeling and other requirements of 40 CFR 
51.112 and must be supported ``by means of a photochemical grid model 
or any other analytical method determined by [EPA] to be at least as 
effective.'' See 40 CFR 51.908. Air quality modeling is used to 
establish attainment emissions targets, that is, a combination of ozone 
precursor emission levels that the area can accommodate without 
exceeding the NAAQS, and to assess whether the proposed control 
strategy will result in attainment of the NAAQS.
    Air quality modeling is performed for a base year and compared to 
air quality monitoring data from that year in order to evaluate model 
performance. Once the performance is determined to be acceptable, 
future year changes to the emissions inventory are simulated with the 
model to determine the effect of emissions reductions on ambient air 
quality. The procedures for modeling ozone as part of an attainment 
demonstration are contained in EPA's ``Guidance on the Use of Models 
and Other Analyses for Demonstrating Attainment of Air Quality Goals 
for the 8-Hour Ozone and PM2.5 NAAQS and Regional Haze'' 
(Guidance). The Guidance also recommends that supplemental analyses be 
performed, and used in combination with the modeling in a Weight of 
Evidence determination that the control strategy will result in 
attainment of the NAAQS. See Guidance p. 17.
    The air quality modeling is described in Chapter 3 of the 2007 
Ozone Plan and documented in Volume One of the Appendices to the 2007 
Ozone Plan, in Appendix A, Exhibit 2 (``Modeling TSD''). We provide a 
brief description of the modeling and a summary of our evaluation of it 
below.
    MAG performed the air quality modeling for the 2007 Ozone Plan 
using the Comprehensive Air Quality Model with Extensions (CAMx) 
photochemical model, incorporating meteorological fields from the 
Mesoscale Model version 5 (MM5). These models have been extensively 
used in developing SIP attainment demonstrations and are identified in 
EPA Guidance as candidate models. See Guidance pp. 139 & 160. While 
there was no intensive field study for this modeling effort, 31 ozone 
stations and 56 meteorological stations provided an ample database of 
routinely collected data for use in model application development and 
performance evaluation.
    EPA recommends that States prepare modeling protocols as part of 
their modeled attainment demonstrations. Guidance, p. 133. The Guidance 
at pp. 133-134 describes the topics to be addressed in this modeling 
protocol. A modeling protocol should detail the procedures for 
conducting the modeling analysis, such as the background and 
objectives, the schedule and organizational structure, selection of 
ozone episodes to model, meteorological and emissions input data 
preparation, model performance evaluation, interpreting modeling 
results, and procedures for using the model to demonstrate whether 
proposed strategies are sufficient to attain the NAAQS. The 2007 Ozone 
Plan's modeling protocol is contained in Volume Two of the Appendices 
to the 2007 Plan, in Appendix I-i, and covers all of the topics 
recommended in the Guidance.
    A key part of the modeling protocol is the selection of ozone 
episodes to be modeled. An attainment demonstration that is robust 
despite natural variability should include modeling of multiple days 
with high ozone concentrations, spanning the range of meteorological 
conditions that lead to exceedances of the NAAQS in the area. See 
Guidance p. 146. Volume two of the Appendices to the 2007 Ozone Plan, 
Attachment II, has a thorough description of the episode selection 
process. A climatology of high ozone days for 1987-2004 was prepared, 
considering synoptic meteorological conditions, temperature, wind 
speed, wind direction, and frequency of high ozone by month, day of 
week, and hour of day. For the more recent 2000-2004 period, ozone 
spatial patterns were examined, and back trajectories prepared to help 
assess whether ozone was locally generated or partly due to transport 
from outside the domain. High temperature occurred on summer days 
whether they exceeded the standard or not, and so was not useful in 
selecting episodes. Typical features of episodes are high ozone 
concentrations northeast of central Phoenix and winds from the east in 
the morning, shifting to south at midday, and then southwesterly in the 
afternoon. Based on the analysis, MAG identified three meteorological 
regimes leading to high ozone concentrations, and six candidate recent 
ozone episodes. On the basis of ozone episode severity and duration, 
MAG chose three of the episodes for modeling. Regime 1 is characterized 
by stagnant winds and purely local generation of ozone; it includes 
some weekend exceedances. It is represented by the July 8-14, 2002 
episode with a maximum ozone concentration of 107 ppb at Maryvale, and 
eight other exceeding sites; this was the episode with the highest 
ozone concentration during the 2000-2004 period. Regime 2 is 
characterized by light winds, with potential for transport

[[Page 21698]]

from the south and southwest. It is represented by the June 3-7, 2002 
episode with a maximum ozone concentration of 92 ppb at Fountain Hills, 
and eleven other exceeding sites. Regime 3 is characterized by a non-
calm winds from other directions. It is represented by the August 5-11, 
2001 episode with a maximum ozone concentration of 99 ppb at Cave 
Creek, and four other exceeding sites. (Both regimes 2 and 3 occur in 
this episode.) The regimes had in common low wind speeds, partial cloud 
cover, and a low pressure system in the southwest of the State and a 
high pressure system in the northeast. EPA finds the selection process 
to be well-documented and well-reasoned, and the selected episodes to 
be a good basis for the attainment demonstration.
    Section IV of the Modeling TSD in Volume one of the Appendices to 
the 2007 Ozone Plan includes extensive statistical and graphical 
analysis demonstrating adequate overall model performance for the June 
2002 episode, but also shows consistent underprediction for the August 
2001 and July 2002 episodes. Under EPA Guidelines, models are used in a 
relative sense (see discussion on Relative Response Factors below), so 
although underpredictions in model performance do not necessarily mean 
that future design values would be underpredicted, they do suggest that 
these two episodes may be less reliable for predicting the effect of 
emissions changes. Thus, primary weight was given to the June 2002 
episode in the attainment demonstration. CAMx model diagnostic 
sensitivity tests were performed by MAG to provide assurance that the 
model is adequately simulating the physical and chemical processes 
leading to ozone in the atmosphere and that the model responds in a 
scientifically reasonable way to emissions changes. The tests included 
zeroing out boundary condition concentrations, initial condition 
concentrations, and various categories of emissions. The model 
responded in a physically reasonable way in each of these tests. MAG 
also undertook sensitivity tests for MM5, which provides meteorological 
input to the CAMx air quality model. These are described in Appendix 
III to the Modeling TSD, and included incorporation of alternative 
observational data sets, and an alternative convection scheme to avoid 
overestimating convective rainfall in this dry southwestern area. The 
meteorological model was found to perform adequately for wind speed, 
wind direction, temperature, and humidity. EPA finds the procedures MAG 
followed to be well-documented and reasonable, and to be acceptable for 
supporting the modeled attainment demonstration.
    For the modeled attainment test, the model is used to predict the 
air quality effect of changes in emissions due to land use changes, 
growth, and the effect of control measures. Under current EPA Guidance, 
the model is used to develop Relative Response Factors (RRFs) that give 
the model's response to emission changes, and the RRFs are applied to 
monitored design value concentrations to arrive at the predicted future 
concentrations. The particulars of the calculation, and which model 
grid cells and modeled days are to be included, are specified in the 
EPA Guidance. Guidance pp. 15, 25, and 155. MAG assessed the 2008 
effect of the seven control measures using the EPA-specified procedure, 
and found the maximum predicted ozone design value to be 84 ppb, which 
is in attainment of the ozone NAAQS. It should be noted that this 
result includes 5 percent additional NOX to create a safety 
margin for the transportation conformity motor vehicle emissions 
budget. EPA agrees that MAG's modeling demonstrates attainment of the 
ozone NAAQS by summer 2008.
    In addition to a modeled attainment demonstration, which focuses on 
locations with an air quality monitor, EPA generally requires an 
Unmonitored Area Analysis. This analysis is intended to ensure that a 
control strategy leads to reductions in ozone at other locations that 
have no monitor but that might have base year (and/or future year) 
ambient ozone levels exceeding the NAAQS. The unmonitored area analysis 
uses a combination of model output and ambient data to identify areas 
that might exceed the NAAQS if monitors were located there. In order to 
examine unmonitored areas in all portions of the modeling domain, EPA 
recommends use of interpolated spatial fields of ambient data combined 
with gridded modeled outputs. Guidance, p. 29. MAG used a variation of 
the EPA-described approach, described in section V of the modeling TSD, 
as a corroboratory screening test. The attainment demonstration passed 
this corroboratory screening test. EPA notes that concentration 
gradients in the supplied spatial isopleth maps appear to be weak 
except in the downtown area where the monitoring network is fairly 
dense and the RRFs themselves have only weak spatial variation. We 
believe the plan's Unmonitored Area Analysis is adequate.
    Finally, the Weight of Evidence Analysis in Appendix V of the 
Modeling TSD, in Volume two of the Appendices to the 2007 Ozone Plan, 
includes several supplemental analyses in support of the attainment 
demonstration. These include ozone air quality trends and precursor 
emission trends, both of which show continued progress and support the 
conclusion that the attainment demonstration is sound. Appendix G of 
Attachment II to the modeling protocol, in Volume two of the Appendices 
to the 2007 Ozone Plan also illustrated the downward ozone trends at 
all ozone monitors. Other analyses examined the sensitivity of the 
model to NOX reductions, the representation of VOC 
speciation in the model, the VOC:NOX ratio as a 
photochemical indicator, Process Analysis, and examination of Weekday 
vs. Weekend effects. These analyses provided observational and modeling 
evidence that the model is correctly replicating the ozone 
photochemistry of the area, and that the Weight of Evidence supports 
the conclusion that the Phoenix-Mesa will attain the ozone NAAQS in 
2008. Additionally, Table 3 below shows that design values (DV) in ppm 
from all monitors in the Phoenix-Mesa nonattainment area, operated by 
three different agencies (Pinal County Air Quality Control District 
(PCAQCD), Maricopa County Air Quality Division (MCAQD), and ADEQ), 
appear to have been meeting the 1997 ozone NAAQS based on monitored 
ozone concentrations since 2005.
    EPA proposes to find that the modeling provides an adequate basis 
for the RACM/RACT, RFP, and attainment demonstrations in the Phoenix-
Mesa 2007 8-Hour Ozone Plan.

                             Table 3--Ozone Design Values From 2005-2010 Monitoring Data in Phoenix-Mesa Nonattainment Area*
--------------------------------------------------------------------------------------------------------------------------------------------------------
              Site                     Site ID               Agency                                  2005-07       2006-08       2007-09       2008-10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Apache Junction.................       04-013-3001  PCAQCD..................  DV (ppm)..........         0.076         0.080         0.075         0.073
                                  ................                            % complete........        99            99            99            99
Buckeye.........................       04-013-4011  MCAQD...................  DV (ppm)..........         0.065         0.066         0.064         0.064

[[Page 21699]]

 
                                  ................                            % complete........       100           100           100           100
Blue Point......................       04-013-9702  MCAQD...................  DV (ppm)..........         0.067         0.064         0.067         0.070
                                  ................                            % complete........       100            94            99            99
Cave Creek......................       04-013-4008  MCAQD...................  DV (ppm)..........         0.079         0.078         0.075         0.074
                                  ................                            % complete........       100           100           100           100
Central Phoenix.................       04-013-3002  MCAQD...................  DV (ppm)..........         0.075         0.074         0.070         0.071
                                  ................                            % complete........        99            97           100           100
Dysart..........................       04-013-4010  MCAQD...................  DV (ppm)..........         0.067         0.067         0.066         0.068
                                  ................                            % complete........        97           100           100           100
Falcon Field....................       04-013-1010  MCAQD...................  DV (ppm)..........         0.076         0.075         0.071         0.070
                                  ................                            % complete........        97            98           100           100
Fountain Hill...................       04-013-9704  MCAQD...................  DV (ppm)..........         0.082         0.079         0.074         0.074
                                  ................                            % complete........        98           100            99           100
Glendale........................       04-013-2001  MCAQD...................  DV (ppm)..........         0.075         0.074         0.071         0.072
                                  ................                            % complete........       100           100           100           100
Humboldt Mountain...............       04-013-9508  MCAQD...................  DV (ppm)..........         0.081         0.078         0.074         0.071
                                  ................                            % complete........       100           100            99           100
North Phoenix...................       04-013-1004  MCAQD...................  DV (ppm)..........         0.082         0.081         0.076         0.077
                                  ................                            % complete........        99            95           100           100
Pinnacle Peak...................       04-013-2005  MCAQD...................  DV (ppm)..........         0.078         0.074         0.072         0.073
                                  ................                            % complete........        99            99           100            99
Rio Verde.......................       04-013-9706  MCAQD...................  DV (ppm)..........         0.083         0.080         0.075         0.072
                                  ................                            % complete........        99            92            96           100
South Phoenix...................       04-013-4003  MCAQD...................  DV (ppm)..........         0.072         0.072         0.071         0.072
                                  ................                            % complete........        99            99            99           100
South Scottsdale................       04-013-3003  MCAQD...................  DV (ppm)..........         0.078         0.077         0.075         0.074
                                  ................                            % complete........        98            97            99            99
JLG Supersite...................       04-013-9997  ADEQ....................  DV (ppm)..........         0.076         0.076         0.075         0.075
                                  ................                            % complete........       100            98           100            99
Tempe...........................       04-013-4005  MCAQD...................  DV (ppm)..........         0.077         0.077         0.073         0.071
                                  ................                            % complete........        97            97           100            98
West Chandler...................       04-013-4004  MCAQD...................  DV (ppm)..........         0.076         0.076         0.073         0.073
                                  ................                            % complete........       100            98           100           100
West Phoenix....................       04-013-0019  MCAQD...................  DV (ppm)..........         0.074         0.078         0.073         0.073
                                  ................                            % complete........       100            99            99           99
--------------------------------------------------------------------------------------------------------------------------------------------------------
* The data in this table has been certified in EPA's Air Quality System (AQS) database in accordance with the requirements of 40 CFR part 58. We provide
  these data only to support our evaluation of the modeling and attainment demonstration and not to support a determination regarding attainment, which
  is not part of today's proposed action.

3. Proposed Action on the Attainment Demonstration
    In order to approve a SIP's attainment demonstration, EPA must make 
several findings:
    First, we must find that the demonstration's technical bases, 
emission inventories and air quality modeling, are adequate. As 
discussed in section IV.A and IV.C.2, we are proposing to approve the 
base year emission inventory and to find the air quality modeling 
adequate to support the attainment demonstration.
    Second, we must find that the SIP provides for expeditious 
attainment through the implementation of all RACM. As discussed above 
in section III.B, we propose to find that the 2007 Ozone Plan provides 
for implementation of all reasonably available control measures 
necessary for expeditious attainment of the 1997 8-hour ozone NAAQS and 
any related RFP requirements in the Phoenix-Mesa nonattainment area.
    Third, we must find that the emission reductions that are relied on 
for attainment are creditable and are sufficient to provide for 
attainment. All of the key attainment measures relied on in the 2007 
Ozone Plan to attain the 1997 8-hour ozone standard by June 15, 2009 
have been adopted and approved into the SIP.
    For the foregoing reasons, we propose to approve the attainment 
demonstration in the 2007 Ozone Plan for the Phoenix-Mesa nonattainment 
area.

D. Reasonable Further Progress Demonstration

    CAA section 172(c)(2) requires that plans for nonattainment areas 
provide for reasonable further progress (RFP). RFP is defined in 
section 171(1) as ``such annual incremental reductions in emissions of 
the relevant air pollutant as are required by [title 1, part D] or may 
reasonably be required by the Administrator for the purpose of ensuring 
attainment of the applicable [standard] by the applicable date.'' The 
ozone implementation rule interprets the RFP requirements for the 
purposes of the 1997 ozone standards, establishing requirements for RFP 
that depend on the area's classification. For areas with attainment 
dates on or before June 15, 2009, RFP would be met by ensuring 
emissions reductions needed for attainment are implemented by the 
beginning of the ozone season prior to the attainment date. See 40 CFR 
51.910(b) and 70 FR 71612.
    The attainment date for the Phoenix-Mesa ozone nonattainment area 
is June 15, 2009, and as discussed in the RACM demonstration and 
control strategy (section IV.B) and the attainment demonstration 
(section IV.C) sections above, all of the control measures needed for 
the attainment demonstration were being implemented prior to the 2008 
ozone season. We propose, therefore, to approve the RFP demonstration 
in the 2007 Ozone Plan.

[[Page 21700]]

E. Contingency Measures

1. Requirements for Contingency Measures
    CAA section 172(c)(9) requires plans to provide for the 
implementation of contingency measures, that achieve additional 
emission reductions, to be undertaken if the area fails to meet RFP 
milestones or fails to attain by its attainment date. These contingency 
measures must be rules or measures that are ready for implementation 
quickly upon failure to meet milestones or attainment. The SIP should 
define trigger mechanisms for the contingency measures, specify a 
schedule for implementation, and indicate that the measures will be 
implemented without significant further action by the State or EPA. See 
68 FR 32802 (June 2, 2002) and 70 FR 71612 (Nov. 29, 2005).
    Additional guidance on the CAA contingency measure provisions is 
found in the General Preamble at 13510-13512 and 13520. The guidance 
indicates that states should adopt and submit contingency measures 
sufficient to provide a 3 percent emission reduction from the adjusted 
RFP base year. This level of reduction is generally acceptable to 
offset emission increase while States are correcting their SIPs. These 
reductions would be beyond what is needed to meet the attainment and/or 
RFP requirement. States may use reductions of either VOC or 
NOX or a combination of both to meet the contingency measure 
requirements. General Preamble at 13520, footnote 6. EPA guidance also 
provides that contingency measures could be implemented early, i.e., 
prior to the milestone or attainment date.\21\ Consistent with this 
policy, states are allowed to use excess reductions from already 
adopted measures to meet the CAA section 172(c)(9) and 182(c)(9) 
contingency measure requirement. This is because the purpose of 
contingency measures is to provide extra reductions that are not relied 
on for RFP or attainment that will provide for continued progress while 
the plan is being revised to fully address the failure to meet the 
required milestone. Nothing in the CAA precludes a State from 
implementing such measures before they are triggered. This approach has 
been approved in numerous SIPs. See 62 FR 15844 (April 3, 1997) 
(approval of the Indiana portion of the Chicago area 15 percent Rate of 
Progress plan); 66 FR 30811 (June 8, 2001) (proposed approval of the 
Rhode Island post-1996 ROP plan); and 66 FR 586 and 66 FR 634 (January 
3, 2001) (approval of the Massachusetts and Connecticut 1-hour ozone 
attainment demonstrations). In the only adjudicated challenge to this 
approach, the court upheld it. See LEAN v. EPA, 382 F.3d 575 (5th Cir. 
2004); 70 FR 71612.
---------------------------------------------------------------------------

    \21\ Memorandum, G.T. Helms, Chief, Ozone/Carbon Monoxide 
Programs Branch to Air Directors, ``Contingency Measures for Ozone 
and Carbon Monoxide Redesignations,'' June 1, 1992.
---------------------------------------------------------------------------

2. Contingency Measures in the 2007 Ozone Plan
    Contingency measure provisions for the Phoenix-Mesa nonattainment 
area and the methodologies used to estimate the emission reductions 
from these measures are described in Chapters 4 and 5 of the 2007 Ozone 
Plan and Section V of Volume 1 of the Appendices to the 2007 Ozone 
Plan. Table 4 lists the five contingency measures and the estimated 
reductions in VOC and NOX emissions from each measure. All 
five contingency measures have already been implemented in the Phoenix-
Mesa nonattainment area, but credit for these measures were not needed 
or used to demonstrate attainment. See 2007 Ozone Plan at pp. 4-7 
through 4-10 and 5-15 through 5-17.

   Table 4--Emission Reductions From Individual Contingency Measures in the Phoenix-Mesa 8-Hour Ozone Modeling
                                                     Domain
----------------------------------------------------------------------------------------------------------------
       Base case emissions on June 6, 2002          VOC  696.13 metric tons/day     NOX  291.82 metric tons/day
----------------------------------------------------------------------------------------------------------------
                                                     Reduction                       Reduction
               Contingency measure                 (metric ton/       Percent      (metric ton/       Percent
                                                       day)          reduction         day)          reduction
----------------------------------------------------------------------------------------------------------------
Expansion of Area A Boundaries..................             1.3             0.2             0.7             0.2
Gross Polluter Option for I/M Waivers...........            <0.1            <0.1            <0.1            <0.1
Increased Waiver Repair Limit Options...........            <0.1            <0.1            <0.1            <0.1
Federal Heavy Duty Diesel Vehicle Standards.....            <0.1            <0.1             2.5             0.9
Federal Nonroad Equipment Standards.............            14.6             2.1            15.6             5.3
                                                 ---------------------------------------------------------------
    Total.......................................            15.9             2.3            18.8             6.4
----------------------------------------------------------------------------------------------------------------
Source: 2007 Ozone Plan at Table 5-6.

a. Expansion of Area A Boundaries
    In 2001, the Arizona legislature passed H.B. 2538 to expand the 
boundaries of Area A, adding additional portions of Maricopa County 
west of Goodyear and Peoria and a small area on the north side of Lake 
Pleasant. The implementation of air quality measures within the new 
Area A boundaries began on January 1, 2002, except for public sector 
alternative fuel requirements to be phased in over a seven-year period. 
MAG modeled this contingency measure by increasing the number of 
registered vehicles in Area A that will be required to participate in 
the I/M program. MAG estimated the emission reductions from this 
contingency measure to be 1.3 metric tons per day of VOC and 0.7 metric 
tons per day of NOX, but did not take credit for this 
measure in the attainment demonstration. See 2007 Ozone Plan at 4-7 and 
4-8.
b. Gross Polluter Option for I/M Waivers
    The Arizona legislature passed S.B. 1427 in 1998 to require vehicle 
owners with vehicles emitting more than twice the emission standard to 
repair the vehicle sufficiently to reduce the emission levels to less 
than twice the standard in order to obtain a compliance waiver from the 
Vehicle Emissions Inspection Program. ADEQ modeled the emission 
reductions for this measure and estimated the emission reductions from 
this contingency measure to be less than 0.1 metric tons per day of VOC 
and less than 0.1 metric tons per day of NOX. MAG but did 
not take credit for this measure in its attainment

[[Page 21701]]

demonstration. See 2007 Ozone Plan at 4-9.
c. Increased Waiver Repair Limit Options
    In 1998, the Arizona legislature passed S.B. 1427 to increase the 
amount a person must spend to repair a failing 1967-1974 vehicle in 
Area A in order to qualify for a waiver from $100 to $200. MAG modeled 
this measure using MOBILE6.2 by reducing the pre-1981 vehicle waiver 
rate from 4 to 2.6 percent. The emission reductions from this 
contingency measure were estimated to be less than 0.1 metric tons per 
day of VOC and less than 0.1 metric tons per day of NOX. MAG 
did not take credit for this measure in its attainment demonstration. 
See 2007 Ozone Plan at 4-9.
d. Federal Heavy Duty Diesel Vehicle Standards
    On January 18, 2001, EPA issued a final rule that set more 
stringent emission standards for new heavy duty diesel vehicles (66 FR 
5001). The rule requires high-efficiency catalytic convertors or 
comparable technologies be installed on 2007 and later model year 
diesel vehicles, and requires ultra-low sulfur fuel be used in all 
onroad diesel vehicles beginning in 2006. MAG modeled emission 
reductions from this federal measure using MOBILE6.2 and estimated VOC 
reductions of less than 0.1 metric tons of VOC per day and 2.5 metric 
tons of NOX per day. MAG did not take credit for this 
measure in its attainment demonstration. See 2007 Ozone Plan at 4-9.
e. Federal Nonroad Equipment Standards
    On October 23, 1998, EPA issued a final rule to set more stringent 
Tier 2 and Tier 3 emission standards for new diesel nonroad equipment 
(63 FR 56967). The Tier 2 program phased in more stringent standards 
for all equipment between 2001 and 2006 and Tier 3 imposed even more 
stringent standards for 50 to 750 horsepower engines in 2006 to 2008. 
Additionally, on June 29, 2004, EPA issued the Clean Air Nonroad 
Diesel--Tier 4 Final rule to require manufacturers to produce nonroad 
engines with emission controls that will reduce emissions by more than 
90 percent (69 FR 38958). The Tier 4 standards apply to nonroad engines 
less than 25 horsepower beginning in 2008 and will apply to larger 
engines over 2011 to 2015. MAG estimated emission reductions from this 
measure using the EPA NONROAD model and projected VOC emission 
reductions of 14.6 metric tons of VOC per day and 15.6 metric tons of 
NOX per day. MAG did not take credit for this measure in its 
attainment demonstration. See 2007 Ozone Plan at 4-9 and 4-10.
3. Proposed Action on the Contingency Measures
    We propose to approve the contingency measures in the 2007 Ozone 
Plan. The contingency measures are consistent with EPA guidance that 
recommends a 3 percent emission reduction. All contingency measures 
have already been implemented but EPA guidance allows for the early 
implementation of contingency measures.

F. Motor Vehicle Emissions Budgets for Transportation Conformity

1. Requirements for Motor Vehicle Emission Budgets
    CAA section 176(c) requires federal actions in nonattainment and 
maintenance areas to conform to the SIP's goals of eliminating or 
reducing the severity and number of violations of the NAAQS and 
achieving expeditious attainment of the standards. Conformity to the 
SIP's goals means that such actions will not: (1) Cause or contribute 
to violations of a NAAQS, (2) worsen the severity of an existing 
violation, or (3) delay timely attainment of any NAAQS or any interim 
milestone.
    Actions that involve Federal Highway Administration (FHWA) or 
Federal Transit Administration (FTA) funding or approval are subject to 
the EPA's transportation conformity rule, codified in 40 CFR part 93, 
subpart A. Under this rule, metropolitan planning organizations (MPOs) 
in nonattainment and maintenance areas coordinate with state and local 
air quality and transportation agencies, EPA, FHWA, and FTA to 
demonstrate that an area's regional transportation plans (RTP) and 
transportation improvement programs (TIP) conform to the applicable 
SIP. This demonstration is typically done by showing that estimated 
emissions from existing and planned highway and transit systems are 
less than or equal to the motor vehicle emission budgets (budgets) 
contained in the SIP. An attainment, maintenance, or RFP SIP should 
establish budgets for the attainment year, each required RFP year, or 
last year of the maintenance plan, as appropriate. Budgets are 
generally established for specific years and specific pollutants or 
precursors. Ozone attainment and RFP plans should establish budgets for 
NOX and VOC. See 40 CFR 93.102(b)(2)(i).
    Before an MPO may use budgets in a submitted SIP, EPA must first 
determine that the budgets are adequate or approve the budgets. In 
order for EPA to find the budgets adequate and approvable, the 
submittal must meet the conformity adequacy requirements of 40 CFR 
93.118(e)(4) and be approvable under all pertinent SIP requirements. To 
meet these requirements, the budgets must reflect all of the motor 
vehicle control measures contained in the attainment and RFP 
demonstrations. See 40 CFR 93.118(e)(4)(v).
2. Motor Vehicle Emission Budgets in the Phoenix-Mesa 2007 Ozone Plan
    The 2007 Ozone Plan for Phoenix Mesa included budgets for VOC and 
NOX for the 2008 attainment year. On October 4, 2007, we 
notified ADEQ and MAG that we found the MVEB for the 2008 attainment 
year adequate for transportation conformity purposes. See letter from 
Deborah Jordan, EPA Region 9, to Nancy Wrona, ADEQ, and Dennis Smith, 
MAG, ``RE: Adequacy Status of Motor Vehicle Emissions Budgets in Eight-
Hour Ozone Plan for the Maricopa Nonattainment Area (June 2007)'', 
October 4, 2007. We published a notice of our findings at 72 FR 60666 
(October 25, 2007). The budget for the 2008 attainment year is 
represented by onroad VOC and NOX emissions for the Phoenix-
Mesa modeling domain on the peak episode day in June 2008 of 72.3 
metric tons per day of VOC and 145.5 metric tons per day of 
NOX. MAG used geographic information systems (GIS) to 
separate the onroad mobile emissions from the Phoenix-Mesa 8-hour ozone 
nonattainment area from the modeling domain, resulting in the estimated 
2008 MVEB of 67.9 metric tons per day of VOC and 138.2 metric tons per 
day of NOX.
3. Proposed Action on the Motor Vehicle Emission Budgets
    Based on our evaluation of the 2007 Ozone Plan and the budgets 
contained in it, which reflect all motor vehicle control measures 
contained in the attainment and RFP demonstration, we are proposing to 
approve the 2008 MVEB.

V. EPA's Proposed Action

    For the reasons discussed above, EPA is proposing to approve 
Arizona's submitted SIP for attaining the 1997 8-Hour Ozone Standard in 
the Phoenix-Mesa nonattainment area.
    Specifically, EPA is proposing to approve under CAA section 
110(k)(3) the following elements of the 2007 Ozone Plan for Phoenix-
Mesa:
    1. The 2002 base year emission inventory as meeting the 
requirements

[[Page 21702]]

of CAA section 172(c)(3) and 40 CFR 51.915;
    2. The reasonably available control measures demonstration as 
meeting the requirements of CAA section 172(c)(1) and 40 CFR 51.912(d);
    3. The reasonable further progress demonstration as meeting the 
requirements of CAA section 172(c)(2) and 40 CFR 51.910;
    4. The attainment demonstration as meeting the requirements of CAA 
section 172(c)(1) and 40 CFR 51.908;
    5. The contingency measures for failure to make RFP or to attain as 
meeting the requirements of CAA section 172(c)(9); and
    6. The motor vehicle emission budgets for the attainment year of 
2008, which are derived from the attainment demonstration, as meeting 
the requirements of CAA section 176(c) and 40 CFR part 93, subpart A.

VI. Statutory and Executive Order Reviews

    Under the Clean Air Act, the Administrator is required to approve a 
SIP submission that complies with the provisions of the Act and 
applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). 
Thus, in reviewing SIP submissions, EPA's role is to approve state 
choices, provided that they meet the criteria of the Clean Air Act. 
Accordingly, this action merely proposes to approve state law as 
meeting Federal requirements and does not impose additional 
requirements beyond those imposed by state law. For that reason, this 
proposed action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Order 
12866 (58 FR 51735, October 4, 1993);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the Clean Air Act; and
     Does not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, this proposed rule does not have tribal implications 
as specified by Executive Order 13175 (65 FR 67249, November 9, 2000), 
because the SIP is not approved to apply in Indian country located in 
the state, and EPA notes that it will not impose substantial direct 
costs on tribal governments or preempt tribal law.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Ozone, Nitrogen 
Dioxide, Volatile Organic Compounds.

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

    Dated: March 30, 2012.
Keith Takata,
Acting Regional Administrator, EPA Region IX.
[FR Doc. 2012-8729 Filed 4-10-12; 8:45 am]
BILLING CODE 6560-50-P


