Illinois Administrative Code › Title 35 - ENVIRONMENTAL PROTECTION › Part 291 - RULES FOR THE PERFORMANCE OF AIR QUALITY IMPACT ANALYSES TO BE USED IN SUPPORT OF PERMIT APPLICATIONS › Subpart A - GENERAL PROVISIONS › Section 291.103 - Overview of Procedures

Current through Register Vol. 48, No. 28, July 12, 2024
a) These
				procedures are designed to serve as guidelines for applicants desiring to
				develop particulate and sulfur dioxide emission limitations for a subject
				emission source.
b) The procedures
				consist of two phases. The first phase requires an analysis of the air quality
				in the vicinity of the subject source for a base year. For the base year
				analysis a point and area source emissions inventory, consisting of emission
				rates and stack parameters for all point sources and emission rates for
				county-wide area sources affecting the study areas, are required. Base year air
				quality, meteorolgical data and the necessary sub-county allocation parameters
				(i.e., employment, population, etc. used to allocate county-wide area source
				emissions to sub-county grid squares) are required to be valid for the time
				frame for which the emissions inventory is valid.
c) The point and area source emissions
				inventory data, along with air quality data and meteorological data, should be
				input to an acceptable air quality dispersion model. This simulation model
				should be validated and calibrated by the applicant. Procedures for and results
				of this effort should be carefully documented. After calibration, the simulated
				air quality in the vicinity of the subject source should be compared with the
				ambient air quality standards as shown in the following table. If a violation
				is indicated with the subject source operating at the proposed emission rates,
				the source must reduce the emission rates so that the AAQS are not exceeded. If
				a violation is not indicated, the source should proceed to Phase II.
Ambient Air Quality Standards
Pollutant
Time of Average
Primary
Standard
Secondary
Standard
Particulate Matter
Annual Geometric Mean
75 ug/m3
60 ug/m3
(TSP)
24 hour
260 ug/m3
150 ug/m3
Sulfur Dioxide
Annual Geometric Mean
80 ug/m3
None
(SO2)
24 hour
365 ug/m3
None
3 hour
None
1300 ug/m3
d)
				Phase II of the analysis is designed to assess the impact of the subject source
				on the ambient air quality for the year 1980, as a minimum. The base year point
				and area source emissions should be multiplied by appropriate growth factors
				developed by the applicant for the specific study area. When determining future
				annual air quality, meteorological data averaged over a minimum period of five
				consecutive years and model calibration data developed for the base year
				analysis should be utilized. Dispersion modeling should again be performed to
				determine if violations of the AAQs are indicated for the projection year(s).
				If a violation is indicated, the subject source must revise its emission rates
				so that the AAQS are not violated. If no violation of the AAQS are indicated by
				dispersion modeling, the subject facility should submit the proper application
				to the Agency for evaluation.