Approval and Promulgation of Implementation Plans; Illinois and Missouri; Ozone

Related Material

Other Related Documents

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: April 17, 2000 (Volume 65, Number 74)]
[Proposed Rules]
[Page 20404-20420]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17ap00-23]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[IL196-1; MO-097-1097; FRL-6578-2]

Approval and Promulgation of Implementation Plans; Illinois and
Missouri; Ozone

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve the Illinois and Missouri 1-hour ozone attainment demonstration
State Implementation Plans (SIPs) for the St. Louis moderate ozone
nonattainment area. The attainment demonstration SIPs are addressed in
Illinois Environmental Protection Agency (IEPA) submittals dated
November 15, 1999 and February 10, 2000 and in Missouri Department of
Natural Resources (MDNR) submittals dated November 10, 1999 and January
19, 2000. In the alternative, the EPA is proposing to disapprove the
attainment demonstration if: Illinois and Missouri do not revise the
attainment demonstration modeling and analyses to incorporate
corrections to the 1996 base year emissions inventory and successfully
demonstrate attainment of the 1-hour standard based on the revised
modeling; Illinois or Missouri do not submit proposed regional Oxides
of Nitrogen (NO_X) emission control regulations for Electric
Generating Units (EGUs) by June 2000 and final adopted regional
(NO_X) emission control regulations for EGUs by December
2000; or Missouri does not submit a proposed motor vehicle emissions
budget by June 30, 2000. The EPA is proposing to: approve an exemption
from (NO_X) emission control requirements for Reasonably
Available Control Technology (RACT) for the Illinois portion of the St.
Louis ozone nonattainment area; extend the ozone attainment date for
the entire St. Louis ozone nonattainment area to November 15, 2003
while retaining the area's current classification as a moderate ozone
nonattainment area; and approve the transportation conformity motor
vehicle emissions budget submitted by Illinois for the Illinois portion
of the St. Louis ozone nonattainment area. The final approvals of the
extension of the ozone attainment date and the motor vehicle emissions
budgets are contingent on the final approval of the ozone attainment
demonstration. The final approval of the attainment demonstration is
contingent on the final approval of the regional (NO_X)
emission control regulations and on the submittal of adequate motor
vehicle emissions budgets. The final approval of the (NO_X)
RACT exemption for Illinois is contingent on the final approval of an
attainment demonstration that does not rely on (NO_X)
emission reductions resulting from (NO_X) RACT implementation
in the Illinois portion of the St. Louis nonattainment area. The EPA is
proposing to disapprove Illinois' request for exemption from
(NO_X) requirements for New Source Review (NSR) and general
conformity.

DATES: Written comments must be received on or before June 16, 2000.

ADDRESSES: Written comments should be sent to: Jay Bortzer, Chief,
Regulation Development Section, Air Programs Branch (AR-18J), U.S.
Environmental Protection Agency, 77 West Jackson Boulevard, Chicago,
Illinois 60604; or Wayne Leidwanger, Chief, Air Planning and
Development Branch, U.S. Environmental Protection Agency, 901 North 5th
Street, Kansas City, Kansas 66101.
Copies of the States' submittals and EPA's Technical Support
Document (TSD) for this proposed rule, and other relevant materials are
available for public inspection during normal business hours at the
following addresses: United States Environmental Protection Agency,
Region 5, Air and Radiation Division, 77 West Jackson Boulevard,
Chicago, Illinois 60604 (please telephone Mark Palermo at (312) 886-
6082 before visiting the Region 5 office); United States Environmental
Protection Agency, Region 7, Air, Radiation, and Toxics Division, 901
North 5th Street, Kansas City, Kansas 66101.

FOR FURTHER INFORMATION CONTACT: Edward Doty, Regulation Development
Section, Air Programs Branch (AR-18J), U.S. Environmental Protection
Agency, Region 5, 77 West Jackson Boulevard, Chicago, Illinois 60604,
Telephone Number (312) 886-6057, E-Mail Address:
doty.edward@epamail.epa.gov; or Aaron Worstell, Air Planning and
Development Branch, U.S. Environmental Protection Agency, Region 7, 901
North 5th Street, Kansas City, Kansas 66101, Telephone Number (913)
551-7787, E-Mail Address: worstell.aaron@epa.gov.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Background
A. Basis for the States' Attainment Demonstration SIPs
B. Components of a Modeled Attainment Demonstration
C. Framework for Proposing Action on the Attainment
Demonstration SIP
D. Criteria for Attainment Date Extensions
E. Criteria for (NO_X) Control Exemptions
II. Technical Review of the Submittals
A. Summary of the State Submittals
1. General Information
2. Modeling Procedures and Input Data
3. Modeling Results
4. Emission Control Strategies
5. Transportation Conformity
6. Petition for NOx Control Exemption
B. Environmental Protection Agency Review of the Submittals
1. Adequacy of the States' Demonstrations of Attainment
2. Adequacy of the Emissions Control Strategies
3. Adequacy of the Request for Extension of the Attainment Date
4. Adequacy of the NOx Control Exemption Request
III. Proposed Action
IV. Administrative Requirements
A. Executive Order 12866
B. Executive Order 13045
C. Executive Order 13084
D. Executive Order 13132
E. Regulatory Flexibility
F. Unfunded Mandates

I. Background

A. Basis for the States' Attainment Demonstration SIPs

What are the Relevant Clean Air Act Requirements?
The Clean Air Act (Act) requires the EPA to establish National
Ambient Air Quality Standards (NAAQS) for certain widespread pollutants
that cause or contribute to air pollution that is reasonably
anticipated to endanger public health or welfare. Clean Air Act

[[Page 20405]]

sections 108 and 109. In 1979, EPA promulgated the 1-hour ground-level
ozone standard of 0.12 parts per million (ppm) (120 parts per billion
(ppb)). 44 FR 8202 (February 8, 1979).
Ground-level ozone is not emitted directly by sources. Rather,
Volatile Organic Compounds (VOC) and NO_X, emitted by a wide
variety of sources, react in the presence of sunlight to form ground-
level ozone. NO_X and VOC are referred to as precursors of
ozone.
An area exceeds the 1-hour ozone standard each time an ambient air
quality monitor records a 1-hour average ozone concentration above
0.124 ppm in any given day (only the highest 1-hour ozone concentration
at the monitor during any 24 hour day is considered when determining
the number of exceedance days at the monitor). An area violates the
ozone standard if, over a consecutive 3-year period, more than 3 days
of exceedances occur at any monitor in the area or in its immediate
downwind environs.
The highest of the fourth-highest daily peak ozone concentrations
over the 3 year period at any monitoring site in the area is called the
ozone design value for the area. The Act, as amended in 1990, required
EPA to designate as nonattainment any area that was violating the 1-
hour ozone standard, generally based on air quality monitoring data
from the 1987 through 1989 period. Clean Air Act section 107(d)(4); 56
FR 56694 (November 6, 1991). The Act further classified these areas,
based on the areas' ozone design values, as marginal, moderate,
serious, severe, or extreme. Marginal areas were suffering the least
significant ozone nonattainment problems, while the areas classified as
severe and extreme had the most significant ozone nonattainment
problems.
The control requirements and date by which attainment is to be
achieved vary with an area's classification. Marginal areas were
subject to the fewest mandated control requirements and had the
earliest attainment date, November 15, 1993. Severe and extreme areas
are subject to more stringent planning requirements but are provided
more time to attain the standard. Serious areas were required to attain
the 1-hour standard by November 15, 1999, and severe areas are required
to attain by November 15, 2005 or November 15, 2007, depending on the
areas' ozone design values for 1987 through 1989. The St. Louis ozone
nonattainment area was classified as moderate and its attainment date
was November 15, 1996. The St. Louis ozone nonattainment area is
defined (40 CFR 81.314 and 81.326) to contain Madison, Monroe, and St.
Clair Counties in Illinois, and Franklin, Jefferson, St. Charles, and
St. Louis Counties and St. Louis City in Missouri.
The requirements of the Act for ozone attainment demonstrations for
moderate ozone nonattainment areas are determined by considering
several sections of the Act. Section 172(c)(6) of the Act requires SIPs
to include enforceable emission limitations, and such other control
measures, means or techniques as well as schedules and timetables for
compliance, as may be necessary to provide for attainment by the
applicable attainment date. Section 172(c)(1) requires the
implementation of all reasonably available control measures (including
Reasonably Available Control Technology (RACT)) and requires the SIP to
provide for attainment of the NAAQS. Section 182(b)(1)(A) requires the
SIP to provide for specific annual reductions in emissions of VOC and
NO_X as necessary to attain the ozone NAAQS by the applicable
attainment date. Finally, section 182(j)(1)(B) requires the use of
photochemical grid modeling or other methods judged to be at least as
effective to demonstrate attainment of the ozone NAAQS in multi-state
ozone nonattainment areas. As part of today's proposal, EPA is
proposing action on the attainment demonstration SIP revisions
submitted by Illinois and Missouri for the St. Louis multi-state ozone
nonattainment area and its associated ozone modeling domain.
In general, an attainment demonstration SIP includes a modeling
analysis showing how an area will achieve the standard by its
attainment date and the emission control measures necessary to achieve
attainment. The attainment demonstration SIPs must include motor
vehicle emission budgets for transportation conformity purposes.
Transportation conformity is a process for ensuring that States
consider the effects of emissions associated with federally-funded
transportation activities on attainment of the standard. Attainment
demonstrations must include the estimates of motor vehicle VOC and
NO_X emissions that are consistent with attainment, which
then act as a budget or ceiling for the purposes of determining whether
transportation plans, programs, and projects conform to the attainment
SIP.
What Is the History and Time Frame for the State Attainment
Demonstration SIP and How Is It Related to Regional NO_X
Controls?
Notwithstanding significant efforts by the States, in 1995 EPA
recognized that many States in the eastern half of the United States
could not meet the November 1994 time frame for submitting an
attainment demonstration SIP because emissions of NO_X and
VOC in upwind States (and the ozone formed by these emissions) affected
these nonattainment areas and the full impact of this effect had not
yet been determined. This phenomenon is called ozone transport.
On March 2, 1995, Mary D. Nichols, EPA's then Assistant
Administrator for Air and Radiation, issued a memorandum to EPA's
Regional Administrators acknowledging the efforts made by the States
but noting the remaining difficulties in making attainment
demonstration SIP submittals. \1\ Recognizing the problems created by
ozone transport, the March 2, 1995 memorandum called for a
collaborative process among the States in the eastern half of the
Country to evaluate and address transport of ozone and its precursors.
This memorandum led to the formation of the Ozone Transport Assessment
Group (OTAG) \2\ and provided for the States to submit the attainment
demonstration SIPs based on the expected time frames for OTAG to
complete its evaluation of ozone transport.
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\1\ Memorandum, ``Ozone Attainment Demonstrations,'' issued
March 2, 1995. A copy of the memorandum may be found on EPA's web
site at: http://www.epa.gov/ttn/oarpg/t1pgm.html.
\2\ Letter from Mary A. Gade, Director, State of Illinois
Environmental Protection Agency to Environmental Council of States
(ECOS) Members, dated April 13, 1995.
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In June 1997, OTAG concluded and provided EPA with recommendations
regarding ozone transport. The OTAG generally concluded that transport
of ozone and the precursor NO_X is significant and should be
reduced regionally to enable States in the eastern half of the Country
to attain the ozone NAAQS.
Building upon the OTAG recommendations and technical analyses, in
November 1997, EPA proposed action addressing the ozone transport
problem. In its proposal, the EPA found that current SIPs in 22 States
and the District of Columbia (23 jurisdictions) were insufficient to
provide for attainment and maintenance of the 1-hour standard because
they did not regulate NO_X emissions that significantly
contribute to ozone transport. 62 FR 60318 (November 7, 1997). The EPA
finalized that rule in September 1998, calling on the 23 jurisdictions,
including Illinois and Missouri, to revise their SIPs to require
NO_X emission reductions within each State to a level
consistent with a NO_X emissions budget identified in the
final rule. 63 FR 57356 (October 27, 1998).

[[Page 20406]]

This final rule is commonly referred to as the NO_X SIP
call.\3\
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\3\ EPA is also requiring regional NO_X emission
reductions under its authority in section 126 of the Act to assure
that reductions occur in upwind areas which have been shown to
impact attainment of the ozone standard in downwind areas.
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Although Illinois and Missouri do not rely on the full ozone
impacts and regional NO_X emission reduction requirements of
the NO_X SIP call in the ozone attainment demonstration SIPs
reviewed here, they do rely, in part, on regional, statewide
NO_X emission reductions for their own States and for States
upwind of Illinois and Missouri. In developing the attainment
demonstration, Illinois and Missouri originally anticipated the
implementation of the NO_X SIP call. Because of a court-
ordered stay of the submission deadline for SIPs in response to the
NO_X SIP call, Illinois and Missouri reconsidered the role
and magnitude of regional NO_X reductions. As noted below,
the NO_X SIP call has substantially been upheld by the U.S.
Court of Appeals for the District of Columbia; accordingly, Illinois
and Missouri may expect even more upwind NO_X emission
reductions than they addressed in developing the attainment
demonstration.
What Is the Time Frame for Taking Action on the Attainment
Demonstration SIPs?
The States submitted the attainment demonstration SIP revisions and
supporting documentation between November 1999 and February 2000. The
EPA believes that it is important to keep the process moving forward in
evaluating these plans and, as appropriate, approving them. Thus, in
today's Federal Register, EPA is proposing to approve the plans if the
States make the additional submittals called for in this document. The
EPA, however, proposes to disapprove the plans if the States do not
submit all of the emission control regulations required to support the
attainment of the 1-hour ozone standard as demonstrated in these SIPs,
do not correct the ozone attainment demonstration modeling to
incorporate changes recently made in the ozone precursor emissions
inventory, or do not have adequate motor vehicle emission budgets to
support transportation conformity determinations. The States are
expected to submit the proposed rules by June 2000, along with any
proposed revisions to the ozone attainment demonstration modeling. The
States are expected to submit final adopted measures, and final
revisions to the attainment demonstration, no later than December 2000.
The EPA intends to act on the State NO_X regulations in
separate rulemaking actions, and will not take final action to approve
the attainment demonstration until it completes action on the rules.
The anticipated schedule for actions on the States' submittals has
been set forth in a recent filing in the United States District Court
for the District of Columbia. Sierra Club v. Carol Browner (D.C.D.C.
No. 98-02733). The EPA intends to complete rulemaking on the attainment
demonstration and attainment date extension for the St. Louis area when
it completes action on the submittals from both Missouri and Illinois
of the additional control measures necessary for the attainment
demonstration. The following outlines the anticipated schedule for EPA
action.
If, by June 30, 2000, either Illinois or Missouri does not submit
proposed regulations for the emission control measures (local and
regional) needed to achieve attainment of the 1-hour ozone standard as
indicated by the attainment demonstration, and any proposed revisions
to the attainment demonstration (to include any proposed revisions to
the motor vehicle emissions budgets) determined to be necessary after
remodeling the 1996 base year ozone levels to account for revised 1996
base year emissions, the EPA intends to take final action on the
proposed reclassification of the St. Louis area \4\ to serious ozone
nonattainment no later than August 1, 2000. If either State does not
submit final adopted emission control measures and any final revisions
to the attainment demonstration (including any final revisions to the
motor vehicle emissions budgets) by December 31, 2000, the EPA intends
to take final action on the reclassification of the area to serious
nonattainment for ozone no later than February 1, 2001. The EPA plans
to send a notice of final rulemaking on the attainment demonstration
and attainment date extension to the Federal Register no later than
February 22, 2001.
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\4\ On March 18, 1999, 64 FR 13384, the EPA proposed to
reclassify the St. Louis area to a serious ozone nonattainment area
based on continued monitored violations of the 1-hour ozone
standard. The EPA also issued a notice of the St. Louis area's
potential eligibility for an attainment date extension.
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Due to the circumstances in which the SIP submissions arose, the
EPA is proposing two alternative courses of action: approval or
disapproval in the alternative. The proposal for approval provides that
the States must take additional actions to obtain final approval.
Failure by the States to complete these additional actions will result
in EPA's disapproval of the SIPs.

B. Components of a Modeled Attainment Demonstration

The EPA provides (Guidance on the Use of Modeled Results to
Demonstrate Attainment of the Ozone NAAQS, EPA-454/B-95-007, June 1996)
that States may rely on a modeled attainment demonstration supplemented
with additional evidence to demonstrate attainment. To have a complete
modeling demonstration submission, States should have submitted the
required modeling analyses and identified any additional evidence that
EPA should consider in evaluating whether the area will attain the
standard. Additional required components are discussed below.
What EPA Guidelines Apply to the Attainment Demonstration Submittals?
The following documents contain EPA's guidelines affecting the
content and review of ozone attainment demonstration submittals:
1. Guideline for Regulatory Application of the Urban Airshed Model,
EPA-450/4-91-013, July 1991. Web site: http://www.epa.gov/ttn/scram/
(file name: ``UAMREG'').
2. Memorandum, ``The Ozone Attainment Test in State Implementation
Plan (SIP) Modeling Demonstrations,'' from Joseph A. Tikvart, Office of
Air Quality Planning and Standards, December 16, 1992.
3. Guidance on Urban Airshed Model (UAM) Reporting Requirements for
Attainment Demonstrations, EPA-454/R-93-056, March 1994. Web site:
http://www.epa.gov/ttn/scram/ (file name: ``UAMRPTRQ'').
4. Memorandum, ``Ozone Attainment Demonstrations,'' from Mary D.
Nichols, Assistant Administrator for Air and Radiation, March 2, 1995.
Web site: http://www.epa.gov/ttn/oarpg/t1pgm.html.
5. Guidance on the Use of Modeled Results to Demonstrate Attainment
of the Ozone NAAQS, EPA-454/B-95-007, June 1996. Web site: http://
www.epa.gov/ttn/scram/ (file name: ``O3TEST'').
6. Memorandum, ``Guidance for Implementing the 1-Hour Ozone and
Pre-Existing PM10 NAAQS,'' from Richard Wilson, Office of Air and
Radiation, December 29, 1997. Web site: http://www.epa.gov/ttn/oarpg/
t1pgm.html.
7. Memorandum, ``Extension of Attainment Dates for Downwind
Transport Areas,'' from Richard D. Wilson, Acting Assistant
Administrator for Air and Radiation, July 16, 1998.

[[Page 20407]]

8. Memorandum, ``Guidance on Motor Vehicle Emissions Budgets in
One-Hour Ozone Attainment Demonstrations,'' from Merrylin Zaw-Mon,
Acting Director of the Regional and State Programs Division, November
3, 1999. Web site: http://www.epa.gov/ttn/oarpg/t1pgm.html.
9. Memorandum, ``Guidance on the Reasonably Available Control
Measures (RACM) Requirement and Attainment Demonstration Submissions
for Ozone Nonattainment Areas,'' from John S. Seitz, Director of Office
of Air Quality Planning and Standards, November 30, 1999.
10. Paper, ``Guidance for Improving Weight of Evidence Through
Identification of Additional Emission Reductions, Not Modeled,'' Office
of Air Quality Planning and Standards, November 1999. Web site: http://
www.epa.gov/ttn/scram/ (file name: ``ADDWOE1H'').
What Are the Modeling Requirements for the Attainment Demonstration?
For purposes of demonstrating attainment, the Act requires States
containing portions of a multi-state moderate ozone nonattainment area
to use photochemical grid modeling or an analytical method judged by
EPA to be as effective. The photochemical grid model is set up using
meteorological conditions conducive to the formation of ozone in the
nonattainment area and its modeling domain. Emissions for a base year
are used to evaluate the model's ability to reproduce actual monitored
air quality values. Following validation of the modeling system for a
base year, emissions are projected to an attainment year to predict air
quality changes in the attainment year due to the emission changes,
which include growth up to and controls implemented by the attainment
year. A modeling domain is chosen that encompasses the nonattainment
area. Attainment is demonstrated when all predicted ozone
concentrations inside the modeling domain are at or below the ozone
standard or an acceptable upper limit above the standard permitted
under certain conditions by EPA's guidance. When the predicted
concentrations are above the standard or upper limit, EPA guidance
allows for an optional weight-of-evidence determination which
incorporates other analyses, such as air quality and emissions trends,
to address uncertainty inherent in the application of photochemical
grid models. This latter approach may be used under certain
circumstances to support the demonstration of attainment.
The EPA guidance identifies the features of a modeling analysis
that are essential to obtain credible results. First, the State must
develop and implement a modeling protocol. The modeling protocol
describes the methods and procedures to be used in conducting the
modeling analyses and provides for policy oversight and technical
review by individuals responsible for developing or assessing the
attainment demonstration (State and local agencies, EPA, the regulated
community, and public interest groups). Second, for purposes of
developing the information to put into the model, the State must select
air pollution days, i.e., days in the past with high ozone
concentrations exceeding the standard, that are representative of the
ozone pollution problem for the nonattainment area. Third, the State
needs to identify the appropriate dimensions of the area to be modeled,
i.e., the modeling domain size. The domain should be larger than the
designated nonattainment area to reduce uncertainty in the boundary
conditions and should include any large upwind sources just outside the
nonattainment area. In general, the domain is considered the local area
where control measures are most beneficial to bring the area into
attainment. Alternatively, a much larger modeling domain may be
established, addressing the impacts of both local and regional emission
control measures on a number of ozone nonattainment areas. In both
cases, the attainment determination is based on the review of ozone
predictions within the local area where control measures are most
beneficial to bring the area into attainment (referred to as the local
modeling domain). Fourth, the State needs to determine the grid
resolution. The horizontal and vertical resolutions in the model affect
the dispersion and transport of emission plumes. Artificially large
grid cells (too few vertical layers and horizontal grids) may dilute
concentrations and may not properly consider impacts of complex
terrain, complex meteorology, and land/water interfaces. Fifth, the
State needs to generate meteorological and emissions data that describe
atmospheric conditions and emissions inputs reflective of the selected
high ozone days. Finally, the State needs to verify that the modeling
system is properly simulating the chemistry and atmospheric conditions
through diagnostic analyses and model performance tests (generally
referred to as model validation). Once these steps are satisfactorily
completed, the model is ready to be used to generate air quality
estimates to support an attainment demonstration.
The modeled attainment test compares model predicted 1-hour daily
maximum ozone concentrations in all grid cells for the attainment year
to the level of the ozone standard. A predicted peak ozone
concentration above 0.124 ppm (124 ppb) indicates that the area is
expected to exceed the standard in the attainment year. This type of
test is often referred to as an exceedance test. The EPA's June 1996
guidance recommends that States use either of two exceedance tests for
the 1-hour ozone standard: a deterministic test or a statistical test.
The deterministic test requires the State to compare predicted 1-
hour daily maximum ozone concentrations for each modeled day \5\ to the
attainment level of 0.124 ppm. If none of the predictions exceed 0.124
ppm, the test is passed.
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\5\ The initial, ``ramp-up'' days for each episode are excluded
from this determination.
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The statistical test takes into account the fact that the form of
the 1-hour ozone standard allows exceedances. If, over a 3 year period,
the area has an average of 1 or fewer ozone standard exceedances per
year at any monitoring site, the area is not violating the standard.
Thus, if the State models a severe day (considering meteorological
conditions that are very conducive to high ozone levels and that should
lead to fewer than 1 exceedance per year at any location in the
nonattainment area and in the modeling domain over a 3 year period),
the statistical test provides that a prediction above 0.124 ppm up to a
certain upper limit may be consistent with attainment of the standard.
The acceptable upper limit above 0.124 ppm is determined by
examining the size of exceedances at monitoring sites which meet or
attain the 1-hour standard. For example, a monitoring site for which
the 4 highest 1-hour average concentrations over a 3 year period are
0.136 ppm, 0.130 ppm, 0.128 ppm, and 0.122 ppm is attaining the
standard. To identify an acceptable upper limit, the statistical
likelihood of observing ozone air quality exceedances of the standard
of various concentrations is equated to the severity of the modeled
day. The upper limit generally represents the maximum ozone
concentration level observed at a location that would be expected to
occur no more than an average of once a year over a 3 year period.
Therefore, if the maximum ozone concentration predicted by the model is
below the acceptable upper limit, in this case 0.136 ppm, then EPA
might conclude that the modeled attainment test is passed. Generally,
exceedances well above 0.124 ppm are very unusual at monitoring sites

[[Page 20408]]

meeting the standard. Thus, these upper limits are rarely significantly
higher than the attainment level of 0.124 ppm.
What Are the Additional Analyses That May Be Considered When the
Modeling Fails To Show Attainment?
When the modeling does not conclusively demonstrate that the area
will attain, additional analyses may be presented to help determine
whether the area will attain the standard. As with other predictive
tools, there are inherent uncertainties associated with modeling and
its results. For example, there are uncertainties in some of the
modeling inputs, such as the meteorological and emissions data bases
for individual days and in the methodology used to assess the severity
of an exceedance at individual sites. The EPA's guidance recognizes
these limitations and provides a means for considering other evidence
to help assess whether attainment of the standard is likely. The
process by which this is done is called a weight-of-evidence
determination.
Under a weight-of-evidence determination, the State can rely on and
EPA will consider factors such as: model performance and results,
episode selection, other modeled attainment tests, e.g., relative
reduction factor analysis; other modeled outputs, e.g., changes in the
predicted frequency and pervasiveness of exceedances and predicted
changes in the design value; actual observed air quality trends;
estimated emission trends; analyses of air quality monitored data; the
responsiveness of the model predictions to further controls; and,
whether there are additional control measures that are or will be
approved into the SIP but were not included in the modeling analysis.
This list is not an exhaustive list of factors that may be considered
and these factors could vary from case to case. The EPA's guidance
contains no limit on how close a modeled attainment test must be to
passing to conclude that other evidence besides an attainment test is
sufficiently compelling to suggest attainment. However, the further a
modeled attainment test is from being passed, the more compelling the
weight-of-evidence needs to be.

C. Framework for Proposing Action on the Attainment Demonstration SIP

Besides the Modeled Attainment Demonstration, What Other Issues Must Be
Addressed in the Attainment Demonstration SIP?
In addition to the modeling analysis and weight-of-evidence
determination demonstrating attainment, the EPA has identified the
following key elements which must be present in order for EPA to
approve the 1-hour attainment demonstration SIP.
1. Clean Air Act Measures and Other Measures Relied on in the Modeled
Attainment Demonstration State Implementation Plan
To receive final approval of the attainment demonstration SIP, the
State must have adopted the emission control measures required under
the Act for the area's classification or must have established negative
source declarations for the source categories for which the area has no
major sources that are subject to Clean Air Act requirements for such
sources. All required emission controls must be implemented prior to
the beginning of the ozone season (April through October in the St.
Louis area, 40 CFR part 58) in the area's attainment year to assure
attainment of the ozone standard in the attainment year.
The attainment demonstration must incorporate the emission impacts
of, and the SIP submittal must address the rule development for, any
additional emission control measures needed to achieve attainment. The
rules for these emission controls must also have been adopted before
the EPA can finally approve the attainment demonstration. The emission
controls for these sources must be implemented prior to the beginning
of the ozone season in the attainment year.
For purposes of fully approving the State's SIP, the State must
adopt and submit all VOC and NO_X control regulations for
affected sources within the State and within the local modeling domain
as reflected in the adopted emission control strategy and as reflected
in the attainment demonstration.
Table 1 presents a summary of the Clean Air Act requirements that
need to be met for a moderate ozone nonattainment area for the 1-hour
ozone standard. These requirements are specified in sections 182(b) and
182(f) of the Act. Information on additional measures that Illinois and
Missouri have adopted and relied on in their SIP submissions is not
shown in this table, but is addressed later in this proposed rule.

Table 1--Clean Air Act Requirements For Moderate Nonattainment Areas

New Source Review (NSR) regulations for VOC and
NO_X, including an offset ratio of 1.15:1 and a major VOC
and NO_X source size cutoff of 100 tons per year (TPY)
Reasonably Available Control Technology (RACT) for VOC
and NO_X
15 percent Rate-Of-Progress (ROP) plan for VOC through
1996
1990 baseline emissions inventory for VOC and
NO_X
Periodic emissions inventory and source emission
statement regulations
Vehicle inspection and maintenance (I/M) program
2. Motor Vehicle Emissions Budget
An attainment demonstration SIP must estimate the motor vehicle
emissions that will be produced in the attainment year and must
demonstrate that this emissions level, when considered with emissions
from all other sources, is consistent with attainment. For
transportation conformity purposes, the estimate of motor vehicle
emissions in a control strategy SIP such as an attainment demonstration
(converted to a typical ozone season week day level) is defined as the
motor vehicle emissions budget. The motor vehicle emissions budget must
meet certain adequacy criteria which are listed in the Transportation
Conformity Rule (40 CFR 93.118) before the budget can be approved as
part of the attainment demonstration SIP. When a motor vehicle
emissions budget is found to be adequate, it is used to determine the
conformity of the transportation plans and programs to the SIP, as
required by section 176(c) of the Act. The motor vehicle emissions
budget must meet adequacy criteria (40 CFR part 93) before the
attainment demonstration SIP can be approved. An appropriately
identified motor vehicle emissions budget is a necessary part of an
attainment SIP.

D. Criteria for Attainment Date Extensions

What Is EPA's Policy With Regard to an Ozone Attainment Date Extension?
The EPA's policy regarding an extension of the ozone attainment
date for the St. Louis area is fully addressed in a EPA's initial
notice of proposed rulemaking dated March 18, 1999. 64 FR 13384. The
March 18, 1999 document proposed to reclassify the St. Louis area to a
serious ozone nonattainment area, but also provided notice of the
area's potential eligibility for an attainment date extension based on
a July 16, 1998 EPA guidance memorandum. In today's document, EPA
proposes to approve the States' request for an attainment date
extension under that policy. The specifics of the attainment date
policy are repeated below for clarity.
On July 16, 1998, a guidance memorandum entitled ``Extension of
Attainment Dates for Downwind Transport Areas'' was issued by the EPA.
That memorandum included

[[Page 20409]]

EPA's interpretation of the Act regarding the extension of attainment
dates for ozone nonattainment areas that have been classified as
moderate or serious for the 1-hour ozone standard and which are
downwind of areas that have interfered with their ability to
demonstrate attainment of the ozone standard by dates prescribed in the
Act. That memorandum stated that the EPA will consider extending the
attainment date for an area or a State that:
(1) has been identified as a downwind area affected by transport
from either an upwind area in the same State with a later attainment
date or an upwind area in another State that significantly contributes
to downwind ozone nonattainment;
(2) has submitted an approvable attainment demonstration with any
necessary, adopted local measures and with an attainment date that
shows it will attain the 1-hour standard no later than the date that
the emission reductions are expected from upwind areas under the final
NO_X SIP call (by 2003) and/or the statutory attainment date
for upwind nonattainment areas, i.e., assuming the boundary conditions
reflecting those upwind emission reductions;
(3) has adopted all applicable local measures required under the
area's current ozone classification and any additional emission control
measures demonstrated to be necessary to achieve attainment, assuming
the emission reductions occur as required in the upwind areas; and
(4) has provided that it will implement all adopted measures as
expeditiously as practicable, but no later than the date by which the
upwind reductions needed for attainment will be achieved.
Once an area receives an extension of its attainment date based on
ozone/precursor transport impacts, the area would no longer be subject
to reclassification to a higher ozone nonattainment classification. If
the St. Louis area is granted an attainment date extension, it would no
longer be subject to a reclassification to serious nonattainment for
ozone and no longer subject to the additional emission control
requirements that would result from the reclassification to serious
nonattainment.
Illinois and Missouri have requested an extension of the attainment
date for the St. Louis nonattainment area in conjunction with the ozone
attainment demonstration submittals. The ozone attainment demonstration
considers 2003 as the revised ozone attainment year. The 2003
attainment year reflects the NO_X emission control deadline
contained in the NO_X SIP call and the NO_X
emission control deadline that EPA is considering to address section
126 petitions currently before it.

E. Criteria for NO_X Control Exemptions

What Are the Clean Air Act Requirements and EPA Policy With Regard to
NO_X Emission Controls and Exemptions From the NO_X
Emission Control Requirements?
The State of Illinois has petitioned for an exemption from excess
NO_X emission reductions pursuant to section 182(f)(2) of the
Act. The State is seeking an exemption from requirements for
NO_X Reasonably Available Control Technology (NO_X
RACT), New Source Review (NSR), and general conformity. The following
discusses the Act requirements and EPA policy with regard to
NO_X emission controls and emission control exemptions,
particularly as such policy deals with the Illinois petition.
Section 182(f)(1) of the Act requires SIPs to include emission
control provisions for major stationary sources of NO_X as
required for major stationary sources of VOC. For moderate and above
ozone nonattainment areas, this includes emission control requirements
for NSR and RACT.
The portions of section 182(f)(1) relevant to St. Louis provide
that the stationary source NO_X requirements shall not apply
where either of the following tests are met:
(1) in any area, the net air quality benefits are greater without
the NO_X reductions from the sources concerned; or
(2) in an ozone nonattainment area, additional NO_X
reductions would not contribute to ozone attainment in the
nonattainment area.
Section 182(f)(2) of the Act states that the application of the
NO_X emission reduction requirements may be limited to the
extent necessary to avoid excess reductions of NO_X.
The main tests for a NO_X emissions control exemption
under EPA policy are discussed in a December 1993 EPA guidance,
Guideline for Determining the Applicability of Nitrogen Oxides
Requirements under Section 182(f). This guidance was issued by the
Office of Air Quality Planning and Standards of the EPA. This guidance
notes that the EPA has determined, based on a review of the Act, that
the excess reduction demonstration for a NO_X emissions
control exemption, under either a ``contribute to attainment'' test or
a ``net ozone benefits'' test, must be tied to an area's ozone
attainment demonstration SIP. For the reasons described in Chapter 6 of
the EPA guidance document, the excess reductions must be those
NO_X emission reductions in excess of the NO_X
emission reductions specified as being necessary for attainment in the
attainment demonstration. The approval of the excess emissions
reduction petition must be contingent on the final approval of the
ozone attainment demonstration.
Details of the current EPA policy regarding NO_X emission
control exemptions and transportation conformity is contained in a
November 14, 1995 final rule (60 FR 44790) amending the transportation
conformity requirements. The final transportation conformity rule
requires consistency with NO_X motor vehicle emission budgets
in control strategy SIPs regardless of whether a NO_X control
exemption has been granted. Areas must establish NO_X
emission budgets unless the State's modeled attainment demonstration
shows that NO_X emissions can essentially grow without limit
due to new federally funded activities or federal actions without
threatening attainment of the ozone standard.
Approval of a NO_X emissions control exemption would
provide a basis for eliminating the requirement to comply with the
transportation conformity rule's build/no-build test and less-than-1990
test for NO_X. The current Illinois submittal, however, does
not request an exemption from transportation conformity NO_X
requirements. In addition, it should be noted that after an area
receives approval to use a motor vehicle emissions budget for the
purposes of conformity determinations, the use of a build/no-build test
or a less-than-1990 emissions test is no longer pertinent. Therefore,
an exemption from NO_X requirements for the build/no-build
test and less-than-1990 emissions test is not necessary once an area's
motor vehicle emissions budget is approved (or found adequate) for use
in transportation conformity determinations. The EPA is proposing the
approval of Illinois' motor vehicle emissions budget in this document.
The requirements for exemption from the NO_X control
requirements of general conformity relevant to Illinois' request are
found in section 182(f)(2) of the Act. Since section 182(f)(2)
NO_X control exemptions are based on a demonstration of
``excess emission reductions,'' a NO_X control exemption
cannot be granted unless the State has made a clear showing through the
ozone attainment demonstration that the emission reductions are indeed
excess (that the attainment demonstration does not rely on such
emission reductions)

[[Page 20410]]

or, where NO_X emission increases (due to new federally-
funded activities or federal actions) are expected to result from
source growth due to an activity for which the NO_X control
exemption is sought, that NO_X emissions can essentially
increase without limit and still not cause ozone standard violations.
Note that activities that are subject to conformity generally involve
emission increases rather than emission decreases. For transportation
conformity determinations, consistency with the motor vehicle emissions
budget is the means for ensuring that increases in such emissions do
not threaten attainment of the ozone standard. In contrast to
transportation conformity, however, general conformity determinations
are not based on consistency with an explicitly identified emissions
budget, since quite often the SIP does not create such budgets for the
emissions-generating activities that are subject to general conformity.
Consequently, a NO_X control exemption for general conformity
cannot be granted under section 182(f)(2) of the Act unless the State
has otherwise clearly demonstrated that NO_X emissions can
essentially increase without limit and still provide for attainment of
the ozone standard.
The situation for NSR, under section 182(f)(2) of the Act, is
analogous. Unless the State has otherwise clearly demonstrated that
NO_X emissions can essentially increase without limit due to
new or modified major stationary sources, the NO_X control
exemption for NSR cannot be approved. A policy memorandum, ``Scope of
Nitrogen Oxides (NO_X) Exemptions,'' dated January 12, 1995,
and signed by G.T. Helms, Group Leader, Ozone/Carbon Monoxide Programs
Branch, EPA, explains that, where EPA grants a NO_X exemption
under the ``excess reductions'' provision, the exemption makes sense
with respect to RACT but not necessarily with respect to NSR. The
distinction would be that RACT emissions impacts are exclusively
emission reductions, whereas NSR impacts often involve emission
increases. It should be noted that NO_X new source
requirements in ozone nonattainment areas would revert to Prevention of
Significant Deterioration (PSD) requirements (PSD allows emission
increases, but only at a controlled rate) if an area is granted an
exemption from NSR NO_X requirements. Therefore, a NSR
NO_X control exemption request, under section 182(f)(2), must
be supported by a demonstration that NO_X emissions due to
new or modified major stationary sources can essentially increase in an
area without limit and not cause ozone standard violations.

II. Technical Review of the Submittals

A. Summary of the State Submittals

1. General Information
When Were the Ozone Attainment Demonstration State Implementation Plan
Revisions Submitted to the Environmental Protection Agency?
Illinois and Missouri have made the following submittals, which in
whole or in part concern the ozone attainment demonstration, a partial
NO_X control exemption for the Illinois portion of the St.
Louis ozone nonattainment area, and an extension of the attainment date
for the St. Louis ozone nonattainment area:
(a) In a submission dated November 10, 1999, the Missouri
Department of Natural Resources (MDNR) submitted an ozone attainment
demonstration along with several additional proposed SIP revisions. The
additional SIP revisions included:
i. Regulations and associated documentation for the control of VOC
emissions from: aerospace manufacture and rework facilities; volatile
organic liquid storage; wood furniture manufacturing operations; batch
process operations; reactor processes and distillation operations
processes in the synthetic organic chemical manufacturing industry; and
existing major sources;
ii. Regulations and associated documentation for the control of
NO_X emissions intended to meet NO_X RACT
requirements of the Act in the Missouri portion of the St. Louis
nonattainment area;
iii. A 15 percent rate-of-progress plan for the control of VOC
emissions in the Missouri portion of the St. Louis area; and
iv. An improved vehicle inspection and maintenance program.
The review of these additional SIP revisions is the subject of
separate technical support documents and rulemakings. See 65 FR 8094,
65 FR 8060, 65 FR 8092, 65 FR 8097, and 65 FR 8083, February 17, 2000.
Only the ozone attainment demonstration portions of the submittal are
considered here;
(b) On November 15, 1999, the IEPA submitted a letter outlining the
ozone attainment strategy for the St. Louis area and the State's
emission control commitments;
(c) On January 19, 2000, the MDNR submitted an additional
supplement to the ozone attainment demonstration. This supplement
reflects revised modeling which was performed at the recommendation of
EPA to include future emission control measures in the St. Louis area,
including Missouri's NO_X RACT program, emission control
contingency measures implemented by both States, and additional VOC
RACT controls implemented by Missouri. The revised analysis also
incorporates other emission inventory corrections based on quality
assurance activities conducted by both States; and
(d) On February 10, 2000, the IEPA submitted its adopted ozone
attainment demonstration SIP. This SIP revision submittal includes a
petition for an exemption from NO_X RACT, NO_X NSR,
and general conformity NO_X requirements for the Illinois
portion of the St. Louis ozone nonattainment area. This SIP revision
also reflects the emission modifications and attainment demonstration
revisions contained in MDNR's January 19, 2000 submittal.
When Were the Submittals Addressed in Public Hearings, and When Were
the Submittals Formally Adopted by the States?
The MDNR held a public hearing on the attainment demonstration on
October 28, 1999, and the Missouri Air Conservation Commission (MACC)
adopted the attainment demonstration on November 8, 1999.
The IEPA held a public hearing on the attainment demonstration on
November 15, 1999. A subsequent public hearing on the updated ozone
attainment demonstration was not held. It must be noted, however, that
the updated ozone attainment demonstration did not include additional
emission controls in Illinois beyond those addressed in the November
15, 1999 public hearing.
What Modeling Approach Was Used in the Analyses?
Illinois and Missouri cooperatively conducted the modeling analyses
and other analyses used to support the attainment demonstration. The
modeling approach is documented in both Illinois' February 10, 2000
ozone attainment demonstration and in Missouri's November 10, 1999
ozone attainment demonstration submittal. Additional modeling analyses
and weight-of-evidence analyses are addressed in Missouri's January 19,
2000 supplemental modeling submittal.
The heart of the modeling system and approach is the Urban Airshed
Model--Version V (UAM-V), developed originally for application in the
Lake Michigan area, but now applied in many other areas. This model was
applied to a large grid system (referred to as Grid M) covering much of
the upper

[[Page 20411]]

Midwest. Grid M was selected to cover many of the ozone precursor
emission sources believed to affect the Lake Michigan area and the St.
Louis area. Grid M was nested inside of a larger grid system covering
the eastern half of the United States (the larger grid system includes
areas referred to as the ``coarse-grid states'' in the OTAG process
used to assess ozone transport in the eastern United States and the
impacts of possible emission control measures to generally reduce
interstate ozone and ozone precursor transport). The data derived from
the larger OTAG grid provided air quality data for the perimeter of
Grid M. It should be noted that for most of the attainment
considerations, the States considered the peak ozone concentrations and
model performance for a sub-portion of Grid M surrounding the St. Louis
ozone nonattainment area (the local modeling domain). The conclusions
discussed later in this document were based on data from this local
modeling domain.
Besides being able to model ozone and other pollutants in nested
horizontal grids, UAM-V can also model individual elevated source
plumes within the modeling grid (plume-in-grid or PiG). Gaussian
dispersion models are used to grow plumes until the plumes essentially
fill grid cells. At these points, the numerical dispersion and
advection components of UAM take over to address further downwind
dispersion and advection.
The following input data systems and analyses were also used as
part of the combined modeling system:
Emissions: UAM-V requires the input of an emissions inventory of
gridded, hourly estimates of CO, NO_X, and speciated VOC
emissions (speciated based on carbon bond types). The States provided
regional and local emission inventories, which were processed through
the Emissions Modeling System--1995 version (EMS-95) to prepare UAM-V
emissions data input files.
The initial emissions inventory files were based on EPA's
NO_X SIP call emissions inventory. Substantial revisions were
made to the Missouri point source and mobile source inventories based
on Missouri's comments on the NO_X SIP call emissions
inventories (Missouri has also made a number of additional attainment
year emission inventory changes as documented in the January 19, 2000
submittal, discussed above). The State submittals describe in detail
the procedures used to develop, and then project, the base year
emission inventories to the 1995/1996 period and to project emissions
to account for growth and control through 2003.
An important deviation from the NO_X SIP call inventory
was the treatment of biogenic emissions emanating from the Ozark
Mountain portion of Missouri. Initial UAM-V modeling results had
indicated that biogenic emissions, consisting primarily of isoprene
from oak trees, were overestimated in the UAM-V model. This
determination was based on a recent study of biogenic emissions and
related VOC concentrations in this area, referred to as the Ozark
Isoprene Experiment (OZIE). Based on initial results from the OZIE
study, the Ozark biogenic emissions predicted from the BEIS2 model have
been adjusted downward 50 percent. Although the investigation of the
Ozark biogenics is not yet completed, and the source of the
overestimation is not yet determined, this gross adjustment to the
inventory is acceptable in this instance because there is a general
consensus between the States and EPA that the UAM-V modeling system
clearly overestimates isoprene in this area.
Meteorology: Meteorological inputs for the UAM-V modeling system
were developed through prognostic meteorological modeling (use of a set
of dynamic equations that describe atmospheric motion and the
distribution and change of meteorological parameters) using the RAMS3a
modeling system developed by Colorado State University. A limited four-
dimensional data assimilation was performed for all days modeled.
RAMS3a output data were re-mapped to the three-dimensional grid
structure of UAM-V.
The IEPA and MDNR have noted that typically there are three types
of meteorological regimes associated with high ozone concentrations in
the St. Louis nonattainment area. The first type of episode occurs when
a surface high pressure system is centered to the east of the St. Louis
area along the Ohio and Tennessee Valleys. This situation brings
southerly wind flow into the area. High ozone in this situation is also
associated with high surface temperatures in the upper 80's and 90's
degrees Fahrenheit ( deg.F) range and with relatively low wind speeds
of less than 10 miles per hour. Precipitation and cloud cover are
minimal.
The second type of high ozone episode is due to stagnation
conditions, when surface winds are calm or with wind speeds less than 5
miles per hour. The wind direction is variable. The temperatures are
relatively high, in the upper 80's or lower 90's.
The third type of episode occurs with the approach of a frontal
system from the north. The front is generally weak with little or no
moisture and little or no cloud cover. Temperature inversions often
form near the surface, trapping pollutants near the surface and
limiting pollutant dispersion.
The following summarizes the meteorology of the two episodes
modeled for the final attainment demonstration:
July 16-19, 1991: On July 16, a migratory high pressure system
arrived in central Pennsylvania producing light southerly winds in the
St. Louis area. Hot, dry weather persisted during this period, with
temperatures reaching 90 deg.F in the St. Louis area. For the July 17
through July 19 period, winds in the St. Louis area became
southwesterly. Wind speeds strengthened by July 19 as a cold front
approached from the northwest.
July 10-14, 1995: On July 10, a high pressure system was centered
over Missouri, resulting in light and variable winds across the St.
Louis area. By July 11 and 12, the high pressure system migrated
eastward to the Tennessee Valley. Winds in the St. Louis area were
southerly and peak temperatures were in the mid to upper 90's deg.F
range. On July 13 and 14, the conditions at the surface remained the
same with the high pressure system centered near the East Coast and
dominating the meteorology in the Eastern and Central United States.
Temperatures continued to peak in the upper 90's with relatively light
southerly winds.
The RAMS3a system was relatively effective in modeling these
meteorological conditions.
Chemistry: Atmospheric chemistry within the modeling grid system
was simulated using the Carbon Bond-Version IV model developed by the
EPA.
Boundary and Initial Conditions: For a 1996 base case evaluation,
initial and boundary conditions were derived from extraction of data
from a larger, 36 kilometer resolution OTAG coarse grid over the grid
cells marking the edges of the Grid M domain. For the 2003 simulations,
various NO_X control levels were applied in the coarse grid
runs to simulate the NO_X impacts expected in the various
States. For States subject to EPA's NO_X SIP call
NO_X emission budgets (including the eastern third of
Missouri, but excluding the western two-thirds of Missouri),
NO_X emission rates for Electric Generating Units (EGUs) were
limited to 0.25 pounds per mmBTU in the modeling system's emissions
data. For the western two-thirds of Missouri, an EGU NO_X
emission rate of 0.35 pounds per

[[Page 20412]]

mmBTU was assumed.\6\ Only Act-required NO_X control levels
and Act-required VOC emission controls were considered for States not
subject to EPA's NO_X SIP call (tightened EGU NO_X
emission levels were not considered for these States).
---------------------------------------------------------------------------

\6\ In Michigan v. EPA, the U.S. Court of Appeals for the
District of Columbia generally upheld the NO_X SIP call,
but remanded EPA's determination to require NO_X
reductions from the entire State of Missouri. The Court explained
that EPA had not developed a sufficient record of evidence to
support requiring emissions reductions from the entire State in
light of modeling results that the OTAG interpreted as indicating
that emissions from the western part of the State may not have a
meaningful impact on downwind nonattainment areas. Michigan v. EPA,
No. 98-1497 (D.C. Cir. March 3, 2000).
---------------------------------------------------------------------------

What High Ozone Periods Were Modeled?
Three high ozone episodes, July 16-19, 1991, July 10-14, 1995, and
June 27-29, 1996 were originally considered for the attainment
demonstration. The 1996 episode was subsequently dropped due to
unacceptable model performance.
In selecting the episodes to be modeled, the States followed the
guidance provided by the EPA. The July 1991 ozone modeling guidance,
Guideline for Regulatory Application of the Urban Airshed Model,
recommends that episodes for modeling be selected to represent
different meteorological regimes observed to correspond with ozone
exceeding the standard. Both stagnation and transport conditions should
be examined. A minimum of 3 primary episode days should be modeled.
Primary episode days are those days for which ozone concentrations
exceeding the standard were monitored in the area.
As noted in the discussion above, the high ozone episodes Illinois
and Missouri selected and modeled have covered more than 3 primary
episode days and have generally covered the types of meteorology
observed along with high ozone in the St. Louis area.
What Procedures and Sources of Projection Data Were Used To Project the
Emissions to Future Years?
To develop the attainment year (2003) EGU emissions, the States
initially considered EPA's 2007 base case emissions developed for the
NO_X SIP call. EPA developed these emissions using the
Integrated Planning Model (IPM). The 2003 base case emissions were
developed from this assuming a linear interpolation between the 1995/
1996 base period emissions and EPA's 2007 base case emissions. A single
growth factor was developed for each State to project the EGU emissions
from the 1995/1996 base period to the 2003 base case levels. Subsequent
emission control strategy tests altered the NO_X emission
limits for these projected source emissions.
For point source, non-EGU emissions, the States projected the 1995/
1996 base period emissions to 2003 using BEA projections of Gross State
Product (GSP). State-specific growth factors were used for Illinois
based on the use of the Emissions Growth Analysis System (EGAS), which
replaced EPA-supplied growth factors.
The 1995 stationary area and non-road emission inventories were
projected to 2003 using BEA projections of GSP. These projections
include the impacts of all applicable Clean Air Act required controls.
The projected non-road emissions were adjusted to account for certain
federal emission control requirements expected to be implemented by
2003, including: the federal small engine standards, Phase II; federal
marine engine standards (for diesel engines of greater than 50
horsepower); federal locomotive standards; and non-road diesel engine
standards.
Projections of on-road emissions from 1995/1996 to 2003 were
accomplished by projecting Vehicle Miles Traveled (VMT) derived from
the Highway Performance Monitoring System (HPMS) and by considering the
VMT growth estimates derived by the EPA from the OTAG process. Travel
demand VMT estimates for 2003 were also obtained for the St. Louis
nonattainment area from the East-West Gateway Coordinating Council. The
Illinois VMT growth estimates reflect a growth rate of 2.0 percent per
year, and the Missouri VMT estimates reflect a growth of 23.5 percent
between 1996 and 2003 (approximately 3 percent per year). Future
emission reductions for on-road emissions were assumed to occur by
2003, including emission reductions resulting from: national low
emissions vehicle standards; implementation of improved vehicle
inspection and maintenance in the St. Louis Metropolitan Statistical
Area (MSA); and reformulated gasoline in the Missouri portion of the
St. Louis MSA.
Biogenic emissions were assumed to remain unchanged between 1995
and 2003.
All projected emissions were processed through EMS-95 to provide
the emission inventory files for use in UAM-V.
3. Modeling Results
How Did the States Validate the Photochemical Modeling Results?
The States conducted a number of statistical analyses to compare
the modeling system's ozone predictions to observed peak ozone
concentrations for the base period. Using the preliminary base period
emissions and meteorological inputs, the States derived statistics
covering: unpaired peak prediction accuracy; normalized bias of data
pairs; and gross errors of data pairs for each of the modeled high
ozone episode days. These results were compared to acceptable accuracy
ranges specified by the EPA. With a few exceptions, the current
modeling results for the July 1991 and July 1995 episodes are in
agreement with EPA-specified criteria. The results of the June 1996
episode modeling, however, did not meet the EPA-specified criteria, and
the episode was, therefore, dropped from further consideration.
Table 2 presents a summary of the model performance statistics for
the St. Louis ozone nonattainment area. These data were taken from
Table 6.1 of Illinois' February 10, 2000 submittal.

Table 2.--Model Ozone Performance Statistics St. Louis Nonattainment Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
July 1991 July 1995
-----------------------------------------------------------------------------------------
7/16 7/17 7/18 7/19 7/10 7/11 7/12 7/13 7/14
--------------------------------------------------------------------------------------------------------------------------------------------------------
Observed (ppb)................................................ 108 140 114 107 125 136 129 154 139
Modeled Base Year (ppb)....................................... 117 135 135 110 83 137 130 131 125
Normalized Bias (percent)..................................... -31.5 -9.7 -14.6 -2.5 -44.3 -8.9 -4.1 -16.3 -5.1
Gross Error (percent)......................................... 33.1 30.6 28.0 19.9 45.6 32.3 26.1 23.7 23.0
Unpaired Peak Accuracy (percent).............................. 8.6 -3.4 18.6 2.9 -32.9 1.4 1.3 -14.6 -14.1
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 20413]]

The model performance statistics can be compared to EPA's recommended
(July 1991, Guideline for Regulatory Application of the Urban Airshed
Model) acceptable model performance statistics:

Normalized Bias: 5 to 15 percent
Gross Error: 30 to 35 percent
Unpaired Peak Accuracy: 15 to 20 percent.

It can be seen that the modeling system does reasonably well and
performs within acceptable performance ranges except for the leading
days of the modeled episodes (the leading days are expected to exhibit
poor model performance and are generally dropped from further
consideration). The model does under predict some peak ozone levels,
particularly on the highest ozone days of July 17, 1991 and July 13-14,
1995. The model over predicts ozone peaks on several other days,
particularly on July 18, 1991. Nonetheless, the modeling system is
judged to be performing adequately and in an acceptable manner to
support emission control strategy considerations.
It should be noted that the above modeling statistics were derived
using base year emissions that did not include the most recent emission
revisions derived for 1996. The States updated the ozone modeling to
incorporate the 2003 emission changes, but did not update the modeling
to incorporate the emission changes for the 1996 base year. The
modeling performance statistics were not determined to account for this
emissions revision. As explained later in this document, the States
must update the modeling to include emission changes in the 1996 base
year inventory and reconfirm that the plan demonstrates attainment
before the EPA can approve the attainment demonstration.
A number of other tests and considerations were also given to the
overall model performance. The performance evaluation considered the
following statistical and graphical information:
Tabular summary of model initial and final base case
performance statistics;
Comparison of the modeling output to the conceptual model
for each episode;
Spatial plots of peak daily and hourly surface
concentrations;
Time series plots of hourly concentrations for the
monitors with the highest ozone concentrations each day; and
Scatter plots of peak observed and predicted ozone
concentrations.

These tests and considerations point to acceptable performance of the
modeling system for the base period.
The States also compared the modeling results to a conceptual model
and found the modeling results to comply with this conceptual model.
What Were the Ozone Modeling Results for the Base Period and for the
Future Attainment Period?
The ozone modeling system was run to simulate ozone concentrations
on selected high ozone days in 1991 and 1995 using emissions for a base
year (1996) and a future year (2003). The resulting St. Louis area
ozone peaks for 1996 and 2003 are given in Table 3. Note that these
modeled ozone peaks reflect the corrected 2003 emissions and modeling
results as documented by Missouri in its January 19, 2000 submittal and
by Illinois in its February 10, 2000 submittal. The 1996 base year
modeled ozone concentrations do not reflect the corrected 1996
emissions. Therefore, the 1996 base year predictions in Table 3 must be
reassessed following correction of the base year modeling to reflect
the correction of the 1996 base year emissions.

Table 3.--Peak Observed and Modeled Ozone Concentrations (ppb) in the St. Louis Ozone Nonattainment Area
----------------------------------------------------------------------------------------------------------------
July 1991 July 1995
Period Date --------------------------------------------------------------
7/17 7/18 7/19 7/11 7/12 7/13 7/14
----------------------------------------------------------------------------------------------------------------
Peak Observed.................................... 140 114 107 136 129 154 139
1996 Base Modeled................................ 135 135 110 137 130 131 125
2003 Post-Control Modeled........................ 122 125 106 125 124 127 118
----------------------------------------------------------------------------------------------------------------

Do the Modeling Results Demonstrate Attainment of the Ozone Standard?
As noted in Table 3, application of the modeling system to the
attainment year emissions through a deterministic approach does not
demonstrate attainment of the 1-hour standard because 3 days are
modeled to have potential exceedances of the standard. The application
of the model in a deterministic approach, as reflected in this table,
does not demonstrate attainment of the standard.
The States also considered the modeling results using a statistical
approach. A statistical approach, as discussed in the June 1996 EPA
guidance, Guidance on Use of Modeled Results to Demonstrate Attainment
of the Ozone NAAQS, permits some modeled exceedances, based on the
severity (ozone conduciveness of a day's meteorology) of the modeled
episode days. Because the guidance leads to the conclusion that none of
the modeled days were severe (as noted later, the IEPA and the MDNR do
believe that 3 of the days are severe based on daily ozone maxima
exceeding the area's ozone design value), the States concluded that the
statistical approach could not be applied in this case.
Because the modeling fails to explicitly demonstrate attainment of
the standard, the States considered additional evidence coupled with
the results from the deterministic approach.
What Weight-of-Evidence Analyses and Determinations Are Used To Support
the Modeled Attainment Demonstration?
A weight-of-evidence determination includes a subjective assessment
of the confidence one has in the modeled results. The more extensive
and credible the corroborative information, the greater the influence
it has in permitting deviations from the deterministic test's benchmark
(modeled attainment at all receptor locations for all days modeled). As
discussed in the June 1996 EPA guidance, Guidance on Use of Modeled
Results to Demonstrate Attainment of the Ozone NAAQS, the weight-of-
evidence given to model results depends on the following factors: (1)
Model performance; (2) confidence in the underlying data bases; (3)
length of the projection period; and (4) how close the results come to
demonstrating attainment for all receptor sites and times modeled (see
Table S.1. of the June 1996 guidance for a complete list of factors
affecting weight-of-evidence determinations and acceptance of model

[[Page 20414]]

results nearly passing the attainment tests).
The model performance and the severity of the modeled episodes are
of particular note. Generally, the closer the modeled results come to
meeting the deterministic test's benchmark, the less compelling other
evidence supporting a deviation from the benchmark needs to be. Model
results showing major improvement in predicted ozone levels can be used
to support the acceptance of the attainment demonstration.
The more extreme the days selected for modeling (the more ozone
conducive the meteorology considered), the greater the weight-of-
evidence support that can be attributed to modeling results exceeding
but nearly meeting the ozone standard. Daily ozone maxima exceeding an
area's ozone design value is an acceptable surrogate for indicating
that these days are extreme. July 17, 1991 and July 13-14, 1995 are
high ozone days because the observed ozone levels on those days are
greater than the area's ozone design value (4th highest daily maxima
over 3 years). Demonstrating attainment on these extreme days implies
greater ozone improvements than the model is predicting may be
achieved. As noted above, the 2003 post-control modeling results are
close to demonstrating attainment, but continue to show modeled
exceedances on July 17, 1991, July 11, 1995, and July 13, 1995. Since
the States believe that these days may be considered to be extreme
ozone days, the States believe that some consideration should be given
to weight-of-evidence determinations. The observed July 11, 1995 peak
observed ozone concentration is at the level of the area's ozone design
value, and, therefore, IEPA and MDNR believe that this day should also
be considered to be an extreme day, supporting the consideration of
weight-of-evidence determinations. The EPA agrees that July 17, 1991
and July 13, 1995 are extreme ozone days and that this should be
considered when making the determination. The EPA, however, does not
agree that July 11, 1995 is extreme, since a day with a with a peak
ozone concentration at the area's design value is not considered to be
extreme.
The States discussed, and the EPA considered, the following factors
and data in aggregate in assessing whether the States have provided
sufficient evidence to support the attainment demonstration despite the
modeled exceedances of the ozone standard. EPA's decision was based on
a composite of the information, not on a single element of the
``weight-of-evidence.''
Reduction of Predicted Exceedances: Modeling for the 1996 base case
showed a total of 418 grid cell-hours that exceeded the 1-hour ozone
standard during the 7 modeled days. For the 2003 post-control
estimates, only 15 grid cell-hours of exceedances were modeled. This
was determined to be a 97 percent improvement in ozone air quality
relative to the 1-hour standard. The States note that this improvement
exceeds the 80 percent improvement criteria contained in one of the
benchmarks of EPA's recommended statistical attainment demonstration
approach. This finding suggests that the attainment strategy will
result in a significant improvement in ozone air quality.
Relative Reduction Factor Attainment Test: The States applied a
relative reduction factor approach recommended by the EPA for
addressing attainment of the 8-hour ozone standard. (``Use of Models
and Other Analyses in Attainment Demonstrations for the 8-Hour Ozone
NAAQS,'' Final Draft, Office of Air Quality Planning and Standards,
EPA, April 1999.) In this approach, the relative changes in ozone
design values for various monitoring sites are determined using the
relative changes in ozone concentrations predicted by the modeling
system in the vicinity of these monitoring sites. All predicted future
design values for the attainment year must be less than 125 ppb to
support the attainment demonstration.
The States based the relative reduction factor approach on the
ozone design values at monitoring sites for the 1995-1997 period. The
relative reduction factors (actually ozone adjustment factors of 1
minus the modeled fractional ozone changes due to emission changes)
were determined from the 1996 and 2003 modeling results. Based on these
analysis values, the results in Table 4 were obtained.

Table 4.--Relative Reduction Factor Results
----------------------------------------------------------------------------------------------------------------
Monitor locations 1-Hour Future
-------------------------------------------------------------------------- design Ozone design
values 1995- adjustment values
State County 1997 factor (ppb)
----------------------------------------------------------------------------------------------------------------
Illinois.................................. Madison...................... 128 0.91 116
St. Clair.................... 108 0.92 99
Missouri.................................. Jefferson.................... 125 0.98 122
St. Charles.................. 131 0.92 120
St. Louis.................... 119 0.98 116
----------------------------------------------------------------------------------------------------------------

The States believe that the relative reduction factor analysis
demonstrates that attainment of the ozone standard is likely in 2003
because all of the resulting future design values as shown in Table 4
are below the ozone standard. However, this analysis reflects modeling
results for 1996 based on emissions subsequently revised by the States.
As noted above, the 1996 modeling was not revised to reflect the
subsequent change in 1996 emissions, whereas the 2003 post-control
modeling was revised to reflect emission changes. This discrepancy has
led to biased modeling results. This analysis must be revisited once
the 1996 base year modeling is corrected to reflect the corrected 1996
base year emissions.
EPA Additional Emission Reductions Calculation: At the request of
the EPA, the States also applied an additional emission reductions
calculation as described in the EPA guideline document, Guidelines for
Improving Weight-of-Evidence Through Identification of Additional
Emission Reductions, Not Modeled. This method also uses an ozone
adjustment factor approach to project a monitored ozone design value to
an attainment year level. This method is based on the use of an area-
wide maximum design value and an ozone adjustment factor based on
relative changes in modeled peak ozone concentrations within and
downwind of the nonattainment area. If the projected design value is
greater than or equal to 125 ppb, this method also leads to estimates
of additional VOC and NO_X emission reductions needed beyond
the selected/modeled control strategy to attain the ozone standard. If
the projected design value is less than or

[[Page 20415]]

equal to 124 ppb, this result supports the attainment demonstration.
To obtain the base design value, the States averaged the area-wide
design values for four 3-year periods, 1993-1995, 1994-1996, 1995-1997,
and 1996-1998. This was done to account for the fact that the base
period emissions cover both 1995 and 1996. The design value periods
considered contained both of these years. The averaging of these design
values also provides a more robust estimate of a base design value and
addresses changes in meteorology. The base ozone design value was
determined to be 133.5 ppb.
The ozone adjustment factor was determined by averaging the modeled
area-wide peak ozone concentrations for the local modeling domain for
1996 and 2003 and taking the ratio of these averages, 2003 to 1996. An
ozone adjustment factor of 0.932 was determined using this procedure.
The base ozone design value and the ozone adjustment factor lead
(133.5 ppb multiplied by 0.932) to a future design value of 124.4 ppb.
This result, while preliminary, shows that the control strategy is
adequate to achieve the ozone standard. This determination, however,
must be reassessed once the 1996 base year modeling is repeated to
reflect the corrected 1996 base year emissions.
Trends Analyses: The MDNR and IEPA have determined or estimated the
emission trends for the St. Louis nonattainment area for the years of
1990 through 2003 for both VOC and NO_X. The emission trends
are plotted in Figures 7.1 and 7.2 of IEPA's February 10, 2000
attainment demonstration submittal. The trends exhibit a significant
decrease in VOC and NO_X emissions within the St. Louis
nonattainment area since 1990. Emissions of NO_X and VOC are
expected to continue to decline through 2003 due to both State and
federal emission control requirements. This includes the impacts of the
States' 15 percent Rate-Of-Progress plans, implementation of VOC RACT
in both States, implementation of NO_X RACT in Missouri,
title IV (Clean Air Act) acid rain control requirements for EGUs, new
vehicle I/M programs in both Illinois and Missouri, and reformulated
gasoline use.
The States have considered air quality trends for 1977 through
1998. Significant downward trends in peak ozone levels have occurred
since the early 1980s. The trend in peak ozone levels, however, have
leveled off at above-standard levels in the last few years.
Nonetheless, the States also note the improvement in air quality
relative to the number of days per year considered to be
meteorologically conducive to high ozone formation. The States compared
the trend of the number of exceedance days per year to the number of
conducive days per year for 1977 through 1998. The number of conducive
days was determined by estimating the number of days with meteorology
meeting the following parameters: (1) Maximum temperatures exceeding 85
degrees Fahrenheit; (2) wind speeds less than 10 miles per hour; (3)
solar radiation exceeding 500 Langleys; (4) little or no precipitation;
and (5) winds from the southeast to west. The number of exceedance days
per year relative to the number of conducive days per year was found to
decline significantly over the years. This downward trend is believed
to be due to the implementation of emission controls.
The States have also considered the trend in background ozone
concentrations for 1989 through 1998. Background ozone concentrations,
reflecting ozone transport into the St. Louis area rather than local
ozone impacts, have been found to trend upward over the most recent
years (1992-1998), pointing to the need to control ozone transport.
This ozone transport is believed, based on the ozone modeling, to play
a significant role in the ozone standard exceedances in the St. Louis
ozone nonattainment area.
Analyses of regional NO_X emissions from Illinois,
Indiana, Kentucky, Missouri, Ohio, and Tennessee and outside of the St.
Louis ozone nonattainment area shows an upward trend over the period of
1985 through 1997, with 1997 total NO_X emissions being 16
percent higher than in 1985. Illinois and Missouri note that the upward
trend in upwind regional NO_X emissions corresponds to the
trend in increased background ozone concentrations. This observation
lends credence to the selected control strategy of controlling regional
NO_X emissions.
The States' analyses of air quality and emission trends do provide
some support for the States' attainment demonstration. Progress in air
quality improvement through the current period (1997-1999) is
demonstrated and future progress in air quality improvement is shown to
be likely. In addition, these analyses lend support to a regional
NO_X reduction as a reasonable approach to achieving
attainment of the ozone standard. Nonetheless, the air quality and
emission trends by themselves do not provide an adequate weight-of-
evidence determination and do not demonstrate that the ozone standard
will be attained by 2003. They simply demonstrate that the States have
made progress towards attaining the standard and are expected to
continue to make such progress.
EPA's NO_X SIP Call Modeling: The States note that the
EPA recommends that States use the results of EPA's NO_X SIP
call modeling as part of the weight-of-evidence for the ozone
attainment demonstrations. Based on the NO_X SIP call
modeling, the post-control St. Louis area maximum ozone design value is
projected to be 124 ppb at the St. Charles County monitoring site in
2007 (subsequent modeling, incorporating additional emission
improvements expected to result from Tier II vehicle emission standards
and the use of low-sulfur gasoline, indicates even lower ozone levels
in the St. Louis area in 2007). It should be noted, however, that the
NO_X SIP call modeling considered NO_X emission
controls that go beyond the level of NO_X controls contained
in the States ozone attainment strategy. The NO_X SIP call
modeling supports the direction of controls in the States' control
strategy (emphasis on regional NO_X controls).
Since the NO_X SIP call will lead to lower ozone levels
in the St. Louis area than the States' selected emission control
strategy, EPA believes that this is additional evidence in support of
the States' attainment demonstration. As noted above, the deterministic
approach failed to unequivocally demonstrate attainment of the 1-hour
standard. The modeling employed by the States assumed NO_X
emission limits higher than those that were assumed in the development
of the NO_X SIP call (regional NO_X control levels
of 0.25 pounds/mmBTU for EGUs in the States' attainment demonstration
versus 0.15 pounds/mmBTU for EGUs along with other regional
NO_X controls in the NO_X SIP call). As a
consequence, the NO_X SIP call will produce lower ozone
transport levels than the control strategy submitted by the States. As
noted above, in Michigan v. EPA, the U.S. Court of Appeals for the
District of Columbia generally upheld the NO_X SIP call, but
remanded EPA's determination to require NO_X emission
reductions from the entire State of Missouri. Michigan v. EPA, No. 98-
1497 (D.C. Cir. March 3, 2000). Since sensitivity analyses have shown
that lower ozone interstate transport levels result in lower peak ozone
levels in the St. Louis area, we expect the implementation of the
NO_X SIP call to result in greater improvement in the ozone
levels than predicted in the States' attainment demonstration modeling,
which only assumed NO_X emission limits of 0.25 pounds per
mmBTU for EGUs in upwind States.

[[Page 20416]]

This factor lends support to the States' attainment demonstration and
supports the view that the combination of NO_X SIP call
controls and the emission controls selected by the States should bring
the St. Louis area into attainment of the 1-hour ozone standard.
4. Emission Control Strategies
What Emission Control Strategies Were Considered in the Attainment
Demonstration?
Illinois' emission control strategy relies on the Clean Air Act
emission control requirements through 2003, including the impacts of
the State's 15 percent Rate-Of-Progress (ROP) plan for the Illinois
portion of the St. Louis ozone nonattainment area, federal emission
controls expected to be implemented by 2003, and a statewide
NO_X emission limit of 0.25 pounds/mmBTU for EGUs of
generating capacity greater than 25 MWe. The NO_X emission
limit for EGUs only applies during the ozone season (May 1 through
September 30). Illinois is in the process of developing state-wide
NO_X emission control regulations to cover this
NO_X limit. Further, it must be noted that Illinois has
committed to tighten this NO_X limit even further if required
to attain the ozone standard in the Lake Michigan area. Illinois is
also assessing the impacts of regional NO_X controls on ozone
transport into the Lake Michigan area, where Illinois must also attain
the 1-hour standard. If modeling indicates that EGU NO_X
emission limits must be tightened beyond 0.25 pounds/mmBTU to attain
the ozone standard in Lake Michigan area, Illinois is committed to
completing rule development to achieve the more stringent
NO_X emission limits. If more stringent NO_X
emission limits are adopted, this will further lower ozone levels in
the St. Louis area. At minimum, the State will adopt an EGU
NO_X emission limit of 0.25 pounds/mmBTU regardless of the
modeling outcome for the Lake Michigan area.\7\
---------------------------------------------------------------------------

\7\ Illinois will also need to adopt controls as necessary to
respond to the NO_X SIP call.
---------------------------------------------------------------------------

Missouri's emission control strategy also relies on the Clean Air
Act emission control requirements through 2003, including impacts of
the State's 15 percent ROP plan, and regional NO_X emission
limits for EGUs. The NO_X emission limits are differentiated
between two portions of the State, with a NO_X emission limit
of 0.25 pounds/mmBTU in the eastern third of the State and a
NO_X emission limit of 0.35 pounds/mmBTU in the western two-
thirds of the State. The emission control strategy also considers the
emission impacts of the following control measures: VOC emission
reductions from implementation of RACT on various sources (see the
discussion of the contents of Missouri's November 10, 1999 submittal
above); NO_X RACT in the Missouri portion of the St. Louis
ozone nonattainment area; and an improved vehicle I/M program.
The emissions control strategy also assumes that all other States
in the ``fine grid'' area of the OTAG analysis (those States subject to
NO_X emission budgets in EPA's NO_X SIP call) would
also limit NO_X emissions from EGUs to 0.25 pounds/mmBTU.
Again note that this differs from the EGU NO_X emission rate
of 0.15 pounds/mmBTU considered for these sources in EPA's
NO_X SIP call and considered by EPA to be acceptable for
background ozone considerations. Illinois and Missouri believe that
these States should be assumed to implement NO_X emission
limits no tighter than those considered for Illinois and Missouri in
the attainment demonstration and has reflected such thinking in the
attainment demonstration. Nonetheless, implementation of the
NO_X SIP call will further lower ozone levels in the St.
Louis area, adding weight-of-evidence and a margin of safety to the
States' attainment demonstration.
Have the States Adopted the Selected Emission Control Strategies and
Have the States Adopted the Emission Control Regulations Needed To
Implement the Emission Control Strategies?
The States have adopted the emission control strategies and all
associated emission control regulations except the state-wide
NO_X emission limits for EGUs. Both States are expected to
complete development of proposed NO_X emission control
regulations for the EGUs by mid-2000 and have final adopted rules no
later than December 2000. Note that the EPA would not finally approve
the attainment demonstration until after it has determined that the
statewide NO_X control regulations are acceptable.
Missouri submitted additional emission control regulations needed
to implement the control strategy with the November 10, 1999 submittal.
These regulations include NO_X RACT, additional VOC RACT, and
the regulations required to implement the State's 15 percent rate-of-
progress plan. These regulations are undergoing separate review and
have been proposed for approval as noted elsewhere in this document.
Illinois has completed all VOC emission control regulations and has
submitted these regulations to the EPA. All of these VOC emission
control regulations have been previously approved by the EPA.
Have the States Adopted all Emission Control Regulations Required by
the Clean Air Act?
Illinois and Missouri have adopted all VOC emission control
requirements required under the Clean Air Act for a moderate ozone
nonattainment area. As noted above, some of these emission control
regulations are currently under review by the EPA. The final approval
of the ozone attainment demonstration is contingent on the final
approval of these regulations.
As noted above, the States have yet to complete the regional,
statewide NO_X emission control regulations needed to
complete the ozone control strategy. Final approval of the attainment
demonstration is contingent on the adoption of these rules. In the
alternative, this proposed rulemaking proposes to disapprove the ozone
attainment demonstration if the States fail to submit the proposed
regional, statewide NO_X control regulations by June 2000 and
final adopted regional, statewide NO_X control regulations by
December 2000. The attainment demonstration will also not be finally
approved if the EPA review of the regional NO_X emission
control regulations, which will be the subject of a separate
rulemaking, concludes that they are not approvable.
5. Transportation Conformity
Did the States Address Transportation Conformity in the Submittals and
Did the States Adopt Motor Vehicle Emission Budgets?
Both Illinois and Missouri have submitted motor vehicle emissions
budgets for the 2003 attainment year in their respective portions of
the St. Louis ozone nonattainment area. These emission budgets must
meet the adequacy criteria in the Transportation Conformity Rule before
the budgets and the attainment demonstration are approved.
The IEPA has submitted an emissions budget of 28.70 tons per day
for VOC and 40.64 tons per day for NO_X in the Illinois
portion of the nonattainment area (the Metro-East area). This budget
has been posted to the EPA web site for public comment and has been
under adequacy review since its submittal to the EPA. The EPA review of
this emissions budget has found that the budget meets all of the
adequacy criteria in section 93.118 of the Transportation Conformity
Rule. These criteria include: (1) The SIP was endorsed by the Governor
(or his designee) and was

[[Page 20417]]

subject to a State public hearing; (2) consultation among federal,
State, and local agencies occurred; (3) the emissions budget is clearly
identified and precisely quantified; (4) the motor vehicle emissions
budget, when considered together with all other emissions, is
consistent with attainment; and (5) the motor vehicle emissions budget
is consistent with and clearly related to the emissions inventory and
control strategy in the submitted attainment demonstration. The EPA is
also required to consider comments submitted to the State at the public
hearing. No comments were received by the State on the transportation
conformity budgets. Also, no comments were received on the Illinois
budget during the adequacy posting.
The EPA is proposing in this document to approve the transportation
conformity budget submitted by Illinois. Comments on this proposed
approval should be submitted to the docket as outlined in the comments
section of this document.
The MDNR included an emissions budget in its November 10, 1999
submittal. An error in the emission estimates was subsequently detected
during the interagency consultation process. The MDNR is revising the
motor vehicle emissions budget, which will be addressed in subsequent
EPA rulemaking. The new Missouri motor vehicle emissions budget will be
posted on EPA's adequacy web site (go to http://www.epa.gov/otaq/traq/
and click on ``conformity,'' then click on ``adequacy web pages'') when
it is received.
As noted elsewhere in this document, Missouri must submit a final
motor vehicle emissions budget which the EPA can determine to be
adequate for conformity assessments (Illinois has already met this
requirement) to avoid disapproval of the attainment demonstration SIP.
Consistent with the schedule for submission of revisions to the States'
attainment demonstration, described previously in this document,
Missouri must submit any proposed revisions to its motor vehicle
emissions budget no later than June 30, 2000. Although these emissions
budgets are undergoing separate adequacy review, it should be noted
that the ozone attainment demonstration will not be given a final
approval until the EPA has determined these emissions budgets to be
adequate to support future transportation conformity reviews.
6. Petition for NO_X Control Exemption
The February 10, 2000, IEPA submittal contains a petition for an
exemption from NO_X emission reduction requirements that are
contained in section 182(f)(1) of the Act. The IEPA requests that this
exemption apply to the RACT, NSR, and general conformity NO_X
requirements for the Illinois portion of the St. Louis nonattainment
area pursuant to section 182(f)(2) of the Act. This exemption is based
on Illinois' assertion that it has demonstrated attainment of the ozone
standard without the need to account for these NO_X emission
controls. Therefore, Illinois contends that these NO_X
emission controls must be considered to be ``excess'' and subject to an
exemption under section 182(f)(2) of the Act.
Illinois believes that the ozone attainment demonstration provides
the requisite technical support for this petition. The NO_X
emission reductions in the attainment demonstration and control
strategy in Illinois are limited to the NO_X emission
reductions from EGUs or other Act-required emission controls not
subject to this petition. Illinois contends (Missouri has not made a
similar argument) that the ozone impacts in the St. Louis area
resulting from NO_X emissions are dominated by the impacts of
regional NO_X emissions from EGUs, and that controlling local
NO_X emissions for other source categories would not
significantly impact ozone levels. Illinois believes that it has shown
in the ozone attainment demonstration modeling that application of the
specific section 182(f) NO_X control requirements would not
meaningfully contribute to attainment of the ozone standard. Review of
the modeling documentation supplied to the EPA, however, does not show
the specific impacts of NO_X RACT, NO_X NSR, or
NO_X general conformity. The modeling documentation does
imply that Illinois applied no specific emission reduction credits for
these NO_X control measures.
It should be noted that Missouri has adopted NO_X RACT
regulations for the St. Louis area and is not seeking an exemption from
NO_X RACT, NO_X NSR, or NO_X general
conformity requirements. The modeling used to support the attainment
demonstration does consider the impacts of NO_X emission
reductions resulting from NO_X RACT implementation in the
Missouri portion of the St. Louis nonattainment area.

B. Environmental Protection Agency Review of the Submittals

1. Adequacy of the States' Demonstrations of Attainment
Did the States Adequately Document the Techniques and Data Used to
Derive the Modeling Input Data and Modeling Results?
The submittals from the States thoroughly documented the techniques
and data used to derive the modeling input data. The submittals
adequately summarized the modeling outputs and the conclusions drawn
from these model outputs. The submittals adequately documented the
States' weight-of-evidence determinations and the bases for concluding
that these determinations adequately support the attainment
demonstration.
Did the Modeling Procedures and Input Data Used Comply With the
Environmental Protection Agency Guidelines and Clean Air Act
Requirements?
Yes. The modeling procedures and input meet the requirements of
EPA's July 1991 and June 1996 ozone modeling guidelines.
Do the Weight-of-Evidence Determinations Support the Attainment
Demonstration?
The weight-of-evidence determinations, when viewed in aggregate,
show that the demonstration of attainment may be adequate for proposed
approval. An issue, however, must be taken with several critical
portions of the weight-of-evidence determinations, namely with the
relative reduction factor results and the additional emission
reductions calculation. As noted above, MDNR revised the emission
inventories for 2003. Based on these emission inventory revisions, the
modeling for 2003 was revised. Such a modeling revision, however, was
not performed for 1996 despite that fact that the 1996 emissions should
also be revised. This may have resulted in a modeling bias in the
results of the 2003 ozone estimates relative to those of 1996 as
modeled. This has led to errors in the estimation of relative reduction
factors and, therefore, may potentially impact the predicted future
ozone design value for the area.
Comparison of 2003 attainment demonstration emissions as submitted
in Illinois' draft October 15, 1999 attainment demonstration with the
2003 attainment demonstration emissions as documented in the February
10, 2000 submittal shows that the nonattainment area VOC emissions have
been

[[Page 20418]]

decreased by approximately 60 tons per day and that the nonattainment
area NO_X emissions have been increased by approximately 6
tons per day. These emission changes incorporate both post-1996
emission reductions as well as changes in emission factors and
calculation procedures. It is the changes in emission factors and
calculation procedures that would also apply to the 1996 emissions.
From the data provided, it is impossible to determine the magnitude of
the emission changes that would have to be applied to the 1996
emissions. Again, this may potentially impact the predicted future
design value, which is a key component of the weight-of-evidence
argument. Accordingly, the States must revise the ozone modeling for
1996 using the updated 1996 emissions and must reassess the results for
the relative reduction factor calculations and the additional
reductions test.
It is inappropriate to conclude at this time that the demonstration
of attainment has fallen short or that the selected emission control
strategy is inadequate. The States are being given an opportunity to
reassess the 1996 modeling results and the associated relative
reduction predictions. It is not expected to take more than a few
months for the States to perform this analysis. If the reassessment of
modeling results causes the States to significantly modify the
attainment strategy, the EPA will re-propose rulemaking on attainment
demonstration SIP revisions, and will seek new public comments on the
revised SIP revisions.
2. Adequacy of the Emission Control Strategies
Do the Emission Control Strategies Meet the Requirements of the Clean
Air Act?
Given the data presented, the selected emission control strategy
may be adequate to achieve attainment of the 1-hour ozone standard.
However, due to the need to reassess the weight-of-evidence
determination, the EPA reserves final judgement on the emissions
control strategy until after it has had an opportunity to review the
revised 1996 ozone modeling results and the revised weight-of-evidence
determinations (the revised relative reduction factor estimates and the
revised additional reductions test results).
Do Emission Control Shortfalls Exist With Regard To Probable Attainment
of the Ozone Standard?
To determine whether there is a shortfall in emission controls, the
need for revised 1996 base year modeling must first be addressed.
Corrections to the 1996 base year emissions inventory will result in
changes to the predicted daily maxima which are presented in Table 3.
Again, the EPA can not fully approve the attainment demonstration or
act on the attainment date extension request until these analyses have
been completed and demonstrate attainment of the standard consistent
with the Act and EPA policy.
Have the States Specified and Adopted Acceptable Motor Vehicle
Transportation Conformity Budgets?
The States have submitted motor vehicle transportation conformity
emission budgets. The budget submitted by the IEPA for Illinois portion
of the St. Louis nonattainment area has been found to meet the adequacy
criteria and is proposed for approval. The budget submitted by the MDNR
needs to be revised and resubmitted. The attainment demonstration will
not be approved until adequate motor vehicle emissions budgets are
submitted and determined to be adequate. The EPA is proposing in the
alternative to disapprove the attainment demonstration if Missouri does
not submit the motor vehicle emissions budget in accordance with the
schedule specified above.
3. Adequacy of the Requests for Extension of the Attainment Date
The policy for the extension of an ozone attainment date is
discussed above. The States' compliance with these requirements is
discussed here.
a. Identification of the Area as a Downwind Area Affected by Ozone
Transport
The States have cited EPA's NO_X SIP call modeling and
analyses documented in the OTAG process to demonstrate that the St.
Louis ozone nonattainment area is affected by an upwind area in another
State that significantly contributes to ozone nonattainment in St.
Louis. Kentucky is the State outside of Illinois and Missouri that
contributes to ozone concentrations in the St. Louis area. On December
17, 1999, EPA took final action on petitions from 8 northeastern States
under section 126 of the Act. In its action, EPA granted those portions
of the petitions for sources for which it made affirmative technical
determinations with respect to the 1-hour ozone standard. These
included sources in Kentucky that make significant contributions to
ozone levels in the St. Louis area. In addition, Illinois and Missouri
have noted the trend towards increasing transport of ozone into the
area from upwind States.
The EPA proposes to find that the States' demonstration of ozone
transport meets the criteria in EPA's attainment date extension policy.
b. Submittal of an Approvable Attainment Demonstration
EPA's review of the attainment demonstration shows that, with the
required changes EPA has specified, it is likely to be approved. In
addition, the States have adopted the emission control measures (RACT,
I/M, and other 15 percent Rate-Of-Progress plan requirements) or are
expected soon to adopt the necessary emission control measures
(regional NO_X emission controls) needed to achieve
attainment.
c. Adoption of all Applicable Local Measures Required Under the Area's
Current Ozone Classification
Missouri has completed the adoption of all local measures required
by the Act for the area's current classification. Illinois has adopted
the necessary local measures, with the exception of NO_X
RACT. If EPA approves Illinois' request for an exemption from the
NO_X RACT requirements, as discussed elsewhere in this
document, this element will have been met.
Both States must adopt and submit regional NO_X
regulations to complete the requirements for the attainment SIP.
Proposed regional NO_X regulations are expected to be
developed by June 2000 and final regional NO_X regulations
must be adopted and submitted by December 2000.
EPA concludes that the States are likely to meet this requirement.
It is noted, however, that the final determination on this issue must
wait until all necessary rules, and the NO_X RACT exemption
request, have been approved by the EPA.
d. Implementation of all Adopted Measures by the Time Upwind Controls
are Expected.
In anticipation of the implementation of upwind regional
NO_X controls in 2003 (the NO_X SIP call requires
implementation of NO_X controls by May 15, 2003), Illinois
and Missouri selected this year as the new attainment period for the
St. Louis area in keeping with EPA's attainment date extension policy.
Both States have committed to fully implement the regional
NO_X controls by 2003 (these NO_X emission controls
must be implemented prior to the start of the ozone season in 2003) and
are expected to have implemented the other control measures prior to
that date. Therefore, the States have met or will meet this condition.

[[Page 20419]]

The EPA concludes that, at the present time, the States are likely
to meet the conditions for an attainment date extension and are in the
process of concluding efforts to meet these conditions. Final
resolution of this issue, however, will not occur until the States have
corrected the noted problem with the attainment demonstration and have
adopted the required regional NO_X regulations.
EPA believes that it is likely that Illinois and Missouri will be
able to meet the criteria for obtaining an attainment date extension
under the conditions contained in EPA's July 16, 1998 attainment date
extension policy. If this occurs, the attainment date for the St. Louis
area is proposed to be extended to November 15, 2003. Even though the
regional NO_X controls will be implemented by the start of
the ozone season in 2003, this later attainment date recognizes that
the States' attainment demonstration does consider other VOC and
NO_X emission reductions that will continue to occur
throughout the ozone season in 2003.
If the States do not correct the attainment demonstration, do not
adopt approvable regional NO_X emission control regulations,
or otherwise fail to meet the conditions of the attainment date
extension policy, EPA will take final action on the proposed
reclassification described in EPA's March 18, 1999 document (64 FR
13384). To the extent that comments received on the March 18, 1999
document, and comments received on EPA's March 25, 1999 document,
``Extension of Attainment Dates for Downwind Transport Areas,'' 64 FR
14441, are applicable to this rulemaking, EPA will address and respond
to these comments in its final rulemaking action.
4. Adequacy of the NO_X Control Exemption Request has
Illinois Adequately Supported its Request for an Exemption From the
Requirement for NO_X emission Control Regulations?
The IEPA has requested an exemption from additional NO_X
RACT, NSR, and general conformity requirements under section 182(f) of
the Clean Air Act based on its contention that the selected emissions
control strategy leads to attainment of the ozone standard without
these additional NO_X emission reductions or NO_X
emission control measures in the Illinois portion of the nonattainment
area. Review of the attainment demonstration against EPA's
NO_X exemption policy discussed above shows that the request
for a NO_X control exemption may be granted in part.
NO_X RACT emission reductions in the Illinois portion of the
nonattainment area are not needed for attainment of the 1-hour ozone
standard, based on the current modeled ozone attainment demonstration.
Illinois, however, will need to show that its request for a
NO_X RACT exemption is still supportable after the States
revise the 1996 base year modeling and show that the emissions control
strategy selected still results in attainment without assuming
NO_X RACT for Illinois sources. Since NO_X RACT
clearly impacts NO_X emissions through NO_X
emission reductions and the attainment demonstration, as it currently
exists, does not rely on these types of NO_X emission
reductions in the Illinois portion of the St. Louis nonattainment area,
Illinois has demonstrated that a NO_X RACT exemption is
justified under section 182(f)(2) of the Act. Although NO_X
RACT would lead to NO_X emission reductions, possibly leading
to further ozone reductions, Illinois has demonstrated that additional
local NO_X emission reductions in the Illinos portion of the
nonattainment area are not needed to demonstrate attainment of the
ozone standard in the St. Louis area.
Section 182(f)(2) of the Act gives States the flexibility to limit
application of the NO_X control requirements to the extent
that any portion of these emission reductions are demonstrated to
result in ``excess reductions.'' In this case, the modeling of the
adopted emission control strategy demonstrates that application of
NO_X RACT in the Illinois portion of the nonattainment area
would result in NO_X emission reductions in excess of those
needed to attain the ozone standard. Therefore, these emission
reductions are not required.
As noted above, the support for a NO_X control exemption
pursuant to section 182(f)(2) of the Act must be based on a
demonstration that NO_X emissions can essentially increase
without limit without causing ozone standard violations. The State has
failed to make such a demonstration. Therefore, EPA believes that a
NO_X control exemption for NSR and general conformity
pursuant to section 182(f)(2) (an ``excess emissions reduction''
argument) is not supported and proposes to disapprove the request
relative to these Clean Air Act requirements.

III. Proposed Action

The EPA proposes to approve the Illinois and Missouri ozone
attainment demonstrations for the St. Louis ozone nonattainment area.
In the alternative, the EPA is proposing to disapprove the ozone
attainment demonstrations if Illinois or Missouri do not revise the
attainment demonstration modeling and associated weight-of-evidence
analyses to incorporate corrections to the 1996 base year emissions
inventory and confirm that attainment is demonstrated. These revisions
must be submitted in proposed form by June 30, 2000 and in final form
by December 31, 2000. In addition, EPA is proposing to disapprove the
ozone attainment demonstrations if: (1) the States do not submit
proposed regional, statewide NO_X emission control
regulations for electric generating units by June 2000 or do not adopt
and submit regional, statewide NO_X emission control
regulations for electric generating units by December 2000; and (2)
Missouri does not submit a proposed motor vehicle emissions budget for
VOC and NO_X by June 30, 2000 and final revisions to the
motor vehicle emissions budget by December 31, 2000. The Environmental
Protection Agency proposes to: (1) approve an exemption from
NO_X emission control requirements for NO_X RACT
for the Illinois portion of the St. Louis ozone nonattainment area; (2)
approve an extension of the ozone attainment date for the St. Louis
ozone nonattainment area to November 15, 2003; and (3) approve the
transportation conformity motor vehicle emissions budget submitted by
Illinois for the Illinois portion of the St. Louis ozone nonattainment
area. The EPA proposes to disapprove Illinois' requested exemption from
NO_X emission control requirements for New Source Review and
general conformity for the Illinois portion of the St. Louis ozone
nonattainment area.

IV. Administrative Requirements

A. Executive Order 12866

The Office of Management and Budget (OMB) has exempted this
regulatory action from Executive Order 12866, entitled ``Regulatory
Planning and Review.''

B. Executive Order 13045

Protection of Children from Environmental Health Risks and Safety
Risks (62 FR 19885, April 23, 1997), applies to any rule that: (1) is
determined to be ``economically significant'' as defined under
Executive Order 12866, and (2) concerns an environmental health or
safety risk that EPA has reason to believe may have a disproportionate
effect on children. If the regulatory action meets both criteria, the
Agency must evaluate the environmental health or safety effects of the
planned rule on children, and explain why the planned regulation is

[[Page 20420]]

preferable to other potentially effective and reasonably feasible
alternatives considered by the Agency.
This rule is not subject to Executive Order 13045 because it does
not involve decisions intended to mitigate environmental health or
safety risks.

C. Executive Order 13084

Under Executive Order 13084, EPA may not issue a regulation that is
not required by statute, that significantly affects or uniquely affects
the communities of Indian tribal governments, and that imposes
substantial direct compliance costs on those communities, unless the
Federal government provides the funds necessary to pay the direct
compliance costs incurred by the tribal governments, or EPA consults
with those governments. If EPA complies by consulting, Executive Order
13084 requires EPA to provide to the Office of Management and Budget,
in a separately identified section of the preamble to the rule, a
description of the extent of EPA's prior consultation with
representatives of affected tribal governments, a summary of the nature
of their concerns, and a statement supporting the need to issue the
regulation. In addition, Executive Order 13084 requires EPA to develop
an effective process permitting elected officials and other
representatives of Indian tribal governments ``to provide meaningful
and timely input in the development of regulatory policies on matters
that significantly or uniquely affect their communities.''
Today's proposed rule does not significantly or uniquely affect the
communities of Indian tribal governments. This action does not involve
or impose any requirements that affect Indian Tribes. Accordingly, the
requirements of section 3(b) of Executive Order 13084 do not apply to
this rule.

D. Executive Order 13132

Federalism (64 FR 43255, August 10, 1999) revokes and replaces
Executive Orders 12612 (Federalism) and 12875 (Enhancing the
Intergovernmental Partnership). Executive Order 13132 requires EPA to
develop an accountable process to ensure ``meaningful and timely input
by State and local officials in the development of regulatory policies
that have federalism implications.'' ``Policies that have federalism
implications'' is defined in the Executive Order to include regulations
that have ``substantial direct effects on the States, on the
relationship between the national government and the States, or on the
distribution of power and responsibilities among the various levels of
government.'' Under Executive Order 13132, EPA may not issue a
regulation that has federalism implications, that imposes substantial
direct compliance costs, and that is not required by statute, unless
the Federal government provides the funds necessary to pay the direct
compliance costs incurred by State and local governments, or EPA
consults with State and local officials early in the process of
developing the proposed regulation. EPA also may not issue a regulation
that has federalism implications and that preempts State law unless the
Agency consults with State and local officials early in the process of
developing the proposed regulation.
This rule will not have substantial direct effects on the States,
on the relationship between the national government and the States, or
on the distribution of power and responsibilities among the various
levels of government, as specified in Executive Order 13132, because it
merely approves a state rule implementing a federal standard, and does
not alter the relationship or the distribution of power and
responsibilities established in the Clean Air Act. Thus, the
requirements of section 6 of the Executive Order do not apply to this
rule.

E. Regulatory Flexibility

The Regulatory Flexibility Act (RFA) generally requires an agency
to conduct a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements unless the agency certifies
that the rule will not have a significant economic impact on a
substantial number of small entities. Small entities include small
businesses, small not-for-profit enterprises, and small governmental
jurisdictions.
This rule will not have a significant impact on a substantial
number of small entities because SIP approvals under section 110 and
subchapter I, part D of the Clean Air Act do not create any new
requirements but simply approve requirements that the State is already
imposing. Therefore, because the Federal SIP approval does not create
any new requirements, I certify that this action will not have a
significant economic impact on a substantial number of small entities.
Moreover, due to the nature of the Federal-State relationship under
the Clean Air Act, preparation of flexibility analysis would constitute
Federal inquiry into the economic reasonableness of state action. The
Clean Air Act forbids EPA to base its actions concerning SIPs on such
grounds. Union Electric Co., v. U.S. EPA, 427 U.S. 246, 255-66 (1976);
42 U.S.C. 7410(a)(2).

F. Unfunded Mandates

Under sections 202 of the Unfunded Mandates Reform Act of 1995
(``Unfunded Mandates Act''), signed into law on March 22, 1995, EPA
must prepare a budgetary impact statement to accompany any proposed or
final rule that includes a Federal mandate that may result in estimated
costs to State, local, or tribal governments in the aggregate; or to
the private sector, of $100 million or more. Under section 205, EPA
must select the most cost-effective and least burdensome alternative
that achieves the objectives of the rule and is consistent with
statutory requirements. Section 203 requires EPA to establish a plan
for informing and advising any small governments that may be
significantly or uniquely impacted by the rule.
EPA has determined that the approval action proposed does not
include a Federal mandate that may result in estimated costs of $100
million or more to either State, local, or tribal governments in the
aggregate, or to the private sector. This Federal action proposes to
approve pre-existing requirements under State or local law, and imposes
no new requirements. Accordingly, no additional costs to State, local,
or tribal governments, or to the private sector, result from this
action.

List of Subjects in 40 CFR Part 52

Environmental protection, Air pollution control, Hydrocarbons,
Nitrogen oxides, Ozone, Reporting and recordkeeping requirements.

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

Dated: March 30, 2000.
Gail C. Ginsberg,
Acting Regional Administrator, Region 5.
Dated: April 7, 2000.
Dennis Grams,
Regional Administrator, Region 7.
[FR Doc. 00-9393 Filed 4-14-00; 8:45 am]
BILLING CODE 6560-50-P

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