Okla. Admin. Code § 252:100-8-1.1
The following words and terms, when used in this Subchapter, shall have the following meaning, unless the context clearly indicates otherwise. Except as specifically provided in this section, terms used in this Subchapter retain the meaning accorded them under the applicable requirements of the Act.
"A stack in existence" means for purposes of OAC 252:100-8-1.5 that the owner or operator had:
(A) begun, or caused to begin, a continuous program of physical on-site construction of the stack; or
(B) entered into binding agreements or contractual obligations, which could not be canceled or modified without substantial loss to the owner or operator, to undertake a program of construction of the stack to be completed in a reasonable time.
"Actual emissions" means, except for Parts 7 and 9 of this Subchapter, the total amount of any regulated air pollutant emitted from a given facility during a particular calendar year, determined using methods contained in OAC 252:100-5-2.1(d).
"Adverse impact on visibility" means, for purposes of Parts 7 and 11, visibility impairment which interferes with the management, protection, preservation, or enjoyment of the visitor's visual experience of the Federal Class I area. This determination must be made by the DEQ on a case-by-case basis taking into account the geographic extent, intensity, duration, frequency and time of visibility impairments, and how these factors correlate with (1) times of visitor use of the Federal Class I area, and (2) the frequency and timing of natural conditions that reduce visibility. This term does not include effects on integral vistas.
"Dispersion technique" means for purposes of OAC 252:100-8-1.5 any technique which attempts to affect 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 that pollutant; or increasing final exhaust gas plume rise by manipulating source process parameters, exhaust gas parameters, stack parameters or combining exhaust gases from several existing stacks into one stack, or other selective handling of exhaust gas streams so as to increase the exhaust gas plume rise. The preceding sentence does not include:
(A) 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.
(B) The merging of exhaust gas streams where:
(i) the source owner or operator documents that the facility was originally designed and constructed with such merged streams;
(ii) after July 8, 1985, such merging is part of a change in operation at the facility that includes the installation of pollution controls and is accompanied by a net reduction in the allowable emissions of a pollutant. This exclusion from "dispersion technique" applicability shall apply only to the emission limitation for the pollutant affected by such change in operation; or
(iii) before July 8, 1985, such merging was part of a change in operation at the facility that included the installation of emissions control equipment or was carried out for sound economic or engineering reasons. Where there was an increase in the emission limitation or, in the event that no emission limitation existed prior to the merging, there was an increase in the quantity of pollutants actually emitted prior to the merging, it shall be presumed that merging was primarily intended as a means of gaining emissions credit for greater dispersion. Before such credit can be allowed, the owner or operator must satisfactorily demonstrate that merging was not carried out for the primary purpose of gaining credit for greater dispersion.
(C) Manipulation of exhaust gas parameters, merging of exhaust gas streams from several existing stacks into one stack, or other selective handling of exhaust gas streams so as to increase the exhaust gas plume rise in those cases where the resulting allowable emissions of sulfur dioxide from the facility do not exceed 5,000 tons per year.
"Emission limitations and emission standards" means for purposes of OAC 252:100-8-1.5 requirements that limit the quantity, rate or concentration of emissions of air pollutants on a continuous basis, including any requirements that limit the level of opacity, prescribe equipment, set fuel specifications or prescribe operation or maintenance procedures for a source to assure continuous reduction.
"Natural conditions" includes naturally occurring phenomena that reduce visibility as measured in terms of light extinction, visual range, contrast, or coloration.
"Secondary emissions" means, for purposes of Parts 7 and 9 of this Subchapter, emissions which occur as a result of the construction or operation of a major stationary source or modification, but do not come from the source or modification itself. Secondary emissions must be specific, well defined, quantifiable, and impact the same general areas as the source or modification which causes the secondary emissions. Secondary emissions may include, but are not limited to:
(A) emissions from trains coming to or from the new or modified stationary source; and,
(B) emissions from any offsite support facility which would not otherwise be constructed or increase its emissions as a result of the construction or operation of the major source or modification.
"Stack" means for purposes of OAC 252:100-8-1.5 any point in a source designed to emit solids, liquids or gases into the air, including a pipe or duct but not including flares.
"Visibility impairment" means any humanly perceptible reduction in visibility (light extinction, visual range, contrast, and coloration) from that which would have existed under natural conditions.
Okla. Admin. Code § 252:100-8-1.1