Indiana Administrative Code
Title 326 - AIR POLLUTION CONTROL DIVISION
Article 1 - GENERAL PROVISIONS
Rule 7 - Stack Height Provisions
Section 7-2 - Definitions
Current through March 20, 2024
Authority: IC 13-1-1-4; IC 13-7-7
Affected: IC 13-1-1
Sec. 2.
"Dispersion technique" means any techniques which effect the concentration of a pollutant in the ambient air by using that portion of a stack which exceeds good engineering practice stack height, varying the rate of emission of a pollutant according to atmospheric conditions or ambient concentrations of the pollutant or by using techniques which have the effect of enhancing plume rise, thereby resulting in greater dispersion. Exemptions from this definition include:
(1) the reheating of a gas stream, following use of a pollution control system, for the purpose of returning the gas to the temperature at which it was originally discharged from the facility generating the gas stream;
(2) the use of smoke management in agricultural or silvicultural programs;
(3) the episodic restrictions on wood burning;
(4) the merging of gas streams where the source or facility was originally designed and constructed with merged gas streams; or
(5) techniques at facilities that emit less than five thousand (5,000) tons per year of sulfur dioxide.
"Elevated terrain" means terrain which exceeds the elevation of the good engineering practice stack height as calculated pursuant to 326 IAC 1-7-4(a).
"Excessive concentrations", for the purpose of determining good engineering practice stack height in a fluid model or field study, means a maximum concentration due to downwash, wakes, or eddy effects proceeded by structures or terrain features which is at least forty percent (40%) in excess of the maximum concentration experienced in the absence of such downwash, wakes, or eddy effects and results in an exceedance of either a national ambient air quality standard (NAAQS) or applicable prevention of significant deterioration (PSD) increment.
"Nearby", as used in 326 IAC 1-7-4(a), means that distance up to five (5) times the lesser of the height or width dimension of a structure but not greater than 0.8 km (one-half (1/2) mile). The height of the structure is measured from the ground level elevation at the base of the stack. For fluid modeling demonstrations, a terrain feature is considered "nearby" if it begins within 0.8 km (one-half (1/2) mile) of the stack, it achieves a height equal to forty percent (40%) of GEP stack height or twenty-six (26) meters whichever is greater, and extends a distance of up to ten (10) times the height of the terrain feature, not to exceed 3.2 kilometers (two (2) miles).
"Stack" means any point in a source designed to emit solids, gases, or liquids into the air, including a pipe or duct but not including flares.
