Current through Register Vol. 48, No. 12, March 22, 2024
a) The analyses
required under this Part must be based on the latest planning assumptions.
1) All planning assumptions must be derived
from the estimates of population, employment, travel, and congestion most
recently approved by the MPO, regional planning commission or other agency
authorized to make such estimates, where available.
2) Any revisions to these estimates used as
part of the conformity determination, including projected shifts in geographic
location or level of population, employment, travel, and congestion, shall be
developed in consultation with the regional planning commission, MPO or other
agency authorized to make such estimates for the urban area.
b) The analyses required under
this Part must be based on the latest and most accurate emission estimation
techniques available as described below, unless such techniques are
inappropriate. If such techniques are inappropriate and written approval of the
USEPA Regional Administrator is obtained for any modification or substitution,
they may be modified or another technique substituted on a case-by-case basis
or, where appropriate, on a generic basis for a specific Federal agency
program. Any modification and substitution shall be done in consultation with
IEPA and USEPA.
1) For motor vehicle
emissions, the most current version of the motor vehicle emissions model
specified by USEPA and available for use in the preparation or revision of SIPs
in this State must be used for the conformity analysis as specified in
subsections (b)(1)(A) and (B) of this Section:
A) The USEPA must publish in the Federal
Register a notice of availability of any new motor vehicle emissions model;
and
B) A grace period of 3 months
shall apply during which the motor vehicle emissions model previously specified
by USEPA as the most current version may be used. Conformity analyses for which
the analysis was begun during the grace period or no more than 3 years before
the Federal Register notice of availability of the latest emission model may
continue to use the previous version of the model specified by USEPA.
2) For non-motor vehicle sources,
including stationary and area source emissions, the latest emission factors
specified by EPA in the "Compilation of Air Pollutant Emission Factors (AP-42)"
as incorporated by reference in Section
255.160
of this Part must be used for the conformity analysis unless more accurate
emission data are available, such as actual stack test data from stationary
sources which are part of the conformity analysis.
c) Any air quality modeling analyses
necessary to demonstrate conformity shall be based on the applicable air
quality models, data bases, and other requirements specified in the most recent
version of the "Guideline on Air Quality Models" Part 51 - Requirements for
Preparation, Adoption, and Submittal of Implementation Plans, 40 CFR 51,
Appendix W, 61 Fed. Reg. 41837 (August 12, 1996) incorporated by reference in
Section
255.160
of this Part, unless:
1) The guideline
techniques are inappropriate, in which case the model may be modified or
another model substituted on a case-by-case basis or, where appropriate, on a
generic basis for a specific Federal agency program; and
2) Any modification of substitution shall be
done in consultation with USEPA.
d) The analyses required under this Part,
except Section
255.220(a)(1)
of this Part, must be based on the total of direct and indirect emissions from
the action and must reflect emission scenarios that are expected to occur under
each of the following cases:
1) The CAA
mandated attainment year or, if applicable, the farthest year for which
emissions are projected in the maintenance plan;
2) The year during which the total of direct
and indirect emissions from the action is expected to be the greatest on an
annual basis; and
3) Any year for
which the applicable SIP specifies an emissions budget.