[Federal Register Volume 65, Number 74 (Monday, April 17, 2000)]
[Proposed Rules]
[Pages 20404-20420]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-9393]


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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 (NOX) emission control regulations for Electric 
Generating Units (EGUs) by June 2000 and final adopted regional 
(NOX) 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 (NOX) 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 (NOX) 
emission control regulations and on the submittal of adequate motor 
vehicle emissions budgets. The final approval of the (NOX) 
RACT exemption for Illinois is contingent on the final approval of an 
attainment demonstration that does not rely on (NOX) 
emission reductions resulting from (NOX) RACT implementation 
in the Illinois portion of the St. Louis nonattainment area. The EPA is 
proposing to disapprove Illinois' request for exemption from 
(NOX) 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: 
[email protected]; 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: [email protected].

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 (NOX) 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 NOX, emitted by a wide 
variety of sources, react in the presence of sunlight to form ground-
level ozone. NOX 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 
NOX 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 
NOX 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 NOX 
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 NOX 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 NOX 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 NOX 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 
NOX emission reductions within each State to a level 
consistent with a NOX emissions budget identified in the 
final rule. 63 FR 57356 (October 27, 1998).

[[Page 20406]]

This final rule is commonly referred to as the NOX SIP 
call.\3\
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    \3\ EPA is also requiring regional NOX 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 NOX emission reduction requirements of 
the NOX SIP call in the ozone attainment demonstration SIPs 
reviewed here, they do rely, in part, on regional, statewide 
NOX 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 NOX SIP call. Because of a court-
ordered stay of the submission deadline for SIPs in response to the 
NOX SIP call, Illinois and Missouri reconsidered the role 
and magnitude of regional NOX reductions. As noted below, 
the NOX 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 NOX 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 NOX 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 NOX 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 
NOX, including an offset ratio of 1.15:1 and a major VOC 
and NOX source size cutoff of 100 tons per year (TPY)
     Reasonably Available Control Technology (RACT) for VOC 
and NOX
     15 percent Rate-Of-Progress (ROP) plan for VOC through 
1996
     1990 baseline emissions inventory for VOC and 
NOX
     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 
NOX 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 NOX emission control deadline 
contained in the NOX SIP call and the NOX 
emission control deadline that EPA is considering to address section 
126 petitions currently before it.

E. Criteria for NOX Control Exemptions

What Are the Clean Air Act Requirements and EPA Policy With Regard to 
NOX Emission Controls and Exemptions From the NOX 
Emission Control Requirements?
    The State of Illinois has petitioned for an exemption from excess 
NOX emission reductions pursuant to section 182(f)(2) of the 
Act. The State is seeking an exemption from requirements for 
NOX Reasonably Available Control Technology (NOX 
RACT), New Source Review (NSR), and general conformity. The following 
discusses the Act requirements and EPA policy with regard to 
NOX 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 NOX 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 NOX 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 NOX reductions from the sources concerned; or
    (2) in an ozone nonattainment area, additional NOX 
reductions would not contribute to ozone attainment in the 
nonattainment area.
    Section 182(f)(2) of the Act states that the application of the 
NOX emission reduction requirements may be limited to the 
extent necessary to avoid excess reductions of NOX.
    The main tests for a NOX 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 NOX 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 
NOX emission reductions in excess of the NOX 
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 NOX 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 NOX motor vehicle emission budgets 
in control strategy SIPs regardless of whether a NOX control 
exemption has been granted. Areas must establish NOX 
emission budgets unless the State's modeled attainment demonstration 
shows that NOX 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 NOX 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 NOX. The current Illinois submittal, however, does 
not request an exemption from transportation conformity NOX 
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 NOX 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 NOX control 
requirements of general conformity relevant to Illinois' request are 
found in section 182(f)(2) of the Act. Since section 182(f)(2) 
NOX control exemptions are based on a demonstration of 
``excess emission reductions,'' a NOX 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 NOX 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 NOX control 
exemption is sought, that NOX 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 NOX control exemption for general conformity 
cannot be granted under section 182(f)(2) of the Act unless the State 
has otherwise clearly demonstrated that NOX 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 
NOX emissions can essentially increase without limit due to 
new or modified major stationary sources, the NOX control 
exemption for NSR cannot be approved. A policy memorandum, ``Scope of 
Nitrogen Oxides (NOX) 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 NOX 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 NOX 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 NOX requirements. Therefore, a NSR 
NOX control exemption request, under section 182(f)(2), must 
be supported by a demonstration that NOX 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 
NOX 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 
NOX emissions intended to meet NOX 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 NOX 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 NOX RACT, NOX NSR, 
and general conformity NOX 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, NOX, 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 
NOX SIP call emissions inventory. Substantial revisions were 
made to the Missouri point source and mobile source inventories based 
on Missouri's comments on the NOX 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 NOX 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 NOX control levels were applied in the coarse grid 
runs to simulate the NOX impacts expected in the various 
States. For States subject to EPA's NOX SIP call 
NOX emission budgets (including the eastern third of 
Missouri, but excluding the western two-thirds of Missouri), 
NOX 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 NOX 
emission rate of 0.35 pounds per

[[Page 20412]]

mmBTU was assumed.\6\ Only Act-required NOX control levels 
and Act-required VOC emission controls were considered for States not 
subject to EPA's NOX SIP call (tightened EGU NOX 
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 NOX SIP call, 
but remanded EPA's determination to require NOX 
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 
NOX 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 NOX 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 NOX 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 NOX. 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 NOX emissions within the St. Louis 
nonattainment area since 1990. Emissions of NOX 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 NOX 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 NOX 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 NOX emissions being 16 
percent higher than in 1985. Illinois and Missouri note that the upward 
trend in upwind regional NOX emissions corresponds to the 
trend in increased background ozone concentrations. This observation 
lends credence to the selected control strategy of controlling regional 
NOX 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 
NOX 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 NOX SIP Call Modeling: The States note that the 
EPA recommends that States use the results of EPA's NOX SIP 
call modeling as part of the weight-of-evidence for the ozone 
attainment demonstrations. Based on the NOX 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 
NOX SIP call modeling considered NOX emission 
controls that go beyond the level of NOX controls contained 
in the States ozone attainment strategy. The NOX SIP call 
modeling supports the direction of controls in the States' control 
strategy (emphasis on regional NOx controls).
    Since the NOX 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 NOX 
emission limits higher than those that were assumed in the development 
of the NOX SIP call (regional NOX 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 
NOX controls in the NOX SIP call). As a 
consequence, the NOX 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 NOX SIP call, but 
remanded EPA's determination to require NOX 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 
NOX SIP call to result in greater improvement in the ozone 
levels than predicted in the States' attainment demonstration modeling, 
which only assumed NOX 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 NOX 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 
NOX emission limit of 0.25 pounds/mmBTU for EGUs of 
generating capacity greater than 25 MWe. The NOX emission 
limit for EGUs only applies during the ozone season (May 1 through 
September 30). Illinois is in the process of developing state-wide 
NOX emission control regulations to cover this 
NOX limit. Further, it must be noted that Illinois has 
committed to tighten this NOX limit even further if required 
to attain the ozone standard in the Lake Michigan area. Illinois is 
also assessing the impacts of regional NOX controls on ozone 
transport into the Lake Michigan area, where Illinois must also attain 
the 1-hour standard. If modeling indicates that EGU NOX 
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 
NOX emission limits. If more stringent NOX 
emission limits are adopted, this will further lower ozone levels in 
the St. Louis area. At minimum, the State will adopt an EGU 
NOX 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 NOX 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 NOX emission 
limits for EGUs. The NOX emission limits are differentiated 
between two portions of the State, with a NOX emission limit 
of 0.25 pounds/mmBTU in the eastern third of the State and a 
NOX 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); NOX 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 
NOX emission budgets in EPA's NOX SIP call) would 
also limit NOX emissions from EGUs to 0.25 pounds/mmBTU. 
Again note that this differs from the EGU NOX emission rate 
of 0.15 pounds/mmBTU considered for these sources in EPA's 
NOX 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 NOX 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 
NOX 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 
NOX emission limits for EGUs. Both States are expected to 
complete development of proposed NOX 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 NOX 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 NOX 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 NOX 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 NOX control regulations by June 2000 and 
final adopted regional, statewide NOX control regulations by 
December 2000. The attainment demonstration will also not be finally 
approved if the EPA review of the regional NOX 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 NOX 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 NOx Control Exemption
    The February 10, 2000, IEPA submittal contains a petition for an 
exemption from NOx 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 NOx 
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 NOx emission 
controls. Therefore, Illinois contends that these NOx 
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 NOx 
emission reductions in the attainment demonstration and control 
strategy in Illinois are limited to the NOx 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 NOx emissions are dominated by the impacts of 
regional NOx emissions from EGUs, and that controlling local 
NOx 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) NOx 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 NOx RACT, NOx NSR, or 
NOx general conformity. The modeling documentation does 
imply that Illinois applied no specific emission reduction credits for 
these NOx control measures.
    It should be noted that Missouri has adopted NOX RACT 
regulations for the St. Louis area and is not seeking an exemption from 
NOX RACT, NOX NSR, or NOX general 
conformity requirements. The modeling used to support the attainment 
demonstration does consider the impacts of NOX emission 
reductions resulting from NOX 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 NOX 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 NOX 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 NOX 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 NOX 
RACT. If EPA approves Illinois' request for an exemption from the 
NOX RACT requirements, as discussed elsewhere in this 
document, this element will have been met.
    Both States must adopt and submit regional NOX 
regulations to complete the requirements for the attainment SIP. 
Proposed regional NOX regulations are expected to be 
developed by June 2000 and final regional NOX 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 NOX 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 
NOX controls in 2003 (the NOX SIP call requires 
implementation of NOX 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 
NOX controls by 2003 (these NOX 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 NOX 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 NOX 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 
NOX 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 NOX 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 NOX Control Exemption Request has 
Illinois Adequately Supported its Request for an Exemption From the 
Requirement for NOX emission Control Regulations?
    The IEPA has requested an exemption from additional NOX 
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 NOX emission reductions or NOX 
emission control measures in the Illinois portion of the nonattainment 
area. Review of the attainment demonstration against EPA's 
NOX exemption policy discussed above shows that the request 
for a NOX control exemption may be granted in part. 
NOX 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 
NOX 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 
NOX RACT for Illinois sources. Since NOX RACT 
clearly impacts NOX emissions through NOX 
emission reductions and the attainment demonstration, as it currently 
exists, does not rely on these types of NOX emission 
reductions in the Illinois portion of the St. Louis nonattainment area, 
Illinois has demonstrated that a NOX RACT exemption is 
justified under section 182(f)(2) of the Act. Although NOX 
RACT would lead to NOX emission reductions, possibly leading 
to further ozone reductions, Illinois has demonstrated that additional 
local NOX 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 NOX 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 
NOX RACT in the Illinois portion of the nonattainment area 
would result in NOX 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 NOX control exemption 
pursuant to section 182(f)(2) of the Act must be based on a 
demonstration that NOX 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 
NOX 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 NOX emission control 
regulations for electric generating units by June 2000 or do not adopt 
and submit regional, statewide NOX 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 NOX 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 
NOX emission control requirements for NOX 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 
NOX 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]
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