Section R18-2-401. Definitions

The following definitions apply to this Article:

1.        “Adverse impact on visibility” means visibility impair- ment that interferes with the management, protection, preservation, or enjoyment of the visitor’s visual experi- ence of a Class I area, as determined according to R18-2- 410.

2.        “Baseline actual emissions” means the rate of emissions, in tons per year, of a regulated NSR pollutant, as deter- mined in accordance with subsections (2)(a) through (c).

a.         For any existing electric  utility steam  generating unit, baseline actual emissions means the average rate, in tons per year, at which the unit actually emit- ted the pollutant during any consecutive 24-month period selected by the owner or operator within the five-year period immediately preceding when the owner or operator begins actual construction of the project. The Director shall allow the use of a differ- ent time period upon a determination that it is more representative of normal source operation.

i.         The average rate shall include fugitive emis- sions to the extent quantifiable, and emissions associated with startups, shutdowns, and mal- functions.

ii.        The average rate shall be adjusted downward to exclude any non-compliant emissions that occurred while the source was operating above any emission limitation that was legally enforceable during the consecutive 24-month period.

iii.      For a regulated NSR pollutant, when a project involves multiple emissions units, only one consecutive 24-month period must be used to determine the baseline actual emissions for the emissions units being changed. A different con- secutive 24-month period can be used for each regulated NSR pollutant.

iv.       The average rate shall not be based on any con- secutive 24-month period for which there is inadequate information for determining annual emissions, in tons per year, and for adjusting this amount if required by subsection (2)(a)(ii).

b.        For any existing emissions unit (other than an elec- tric utility steam generating unit), baseline actual emissions means the average rate, in tons per year, at which the unit actually emitted the pollutant during any consecutive 24-month period selected by the owner or operator within the 10-year period immedi- ately preceding either the date the owner or operator begins actual construction of the project, or the date a complete permit application is received by the Administrator for a permit required under 40 CFR

52.21 or by the Director for a permit required under the state implementation plan, whichever is earlier, except that the 10-year period shall not include any period earlier than November 15, 1990.

i.         The average rate shall include fugitive emis- sions to the extent quantifiable, and emissions associated with startups, shutdowns, and mal- functions.

ii.        The average rate shall be adjusted downward to exclude any non-compliant emissions that occurred while the source was operating above any emission limitation that was legally enforceable during the consecutive 24-month period. This provision applies to excess emis- sions associated with a malfunction.

Department of Environmental Quality – Air Pollution Control

iii.      The average rate shall be adjusted downward to exclude any emissions that would have exceeded an emission limitation with which the major source must currently comply, had such major source been required to comply with such limitations during the consecutive 24- month period. However, if an emission limita- tion is part of a maximum achievable control technology standard that the Administrator pro- posed or promulgated under 40 CFR 63, the baseline actual emissions need only be adjusted if the state of Arizona has taken credit for such emissions reductions in an attainment demon- stration or maintenance plan submitted to the Administrator pursuant to section 110(a)(1) of the Act.

iv.       For a regulated NSR pollutant, when a project involves multiple emissions units, only one consecutive 24-month period must be used to determine the baseline actual emissions for all existing emissions units affected by the project. A different consecutive 24-month period may be used for each regulated NSR pollutant.

v.        The average rate shall not be based on any con- secutive 24-month period for which there is inadequate information for determining annual emissions, in tons per year, and for adjusting this amount if required by subsection (2)(b)(ii) or (iii).

c.         For a new emissions unit, the baseline actual emis- sions for purposes of determining the emissions increase that will result from the initial construction and operation of such unit shall equal  zero;  and thereafter, for all other purposes, shall equal the unit’s potential to emit.

d.        For a PAL for a stationary source, the baseline actual emissions shall be calculated for existing electric utility steam generating units in accordance with the procedures in subsection (2)(a), for other existing emissions units in accordance with the procedures contained in subsection (2)(b), and for new emis- sions units in accordance with the procedures con- tained in subsection (2)(c).

3.        “Basic design parameter” means:

a.         Except as provided in subsection (3)(c), for a pro- cess unit at a steam electric generating facility, the owner or operator may select as its basic design parameters either maximum hourly heat input and maximum hourly fuel consumption rate or maxi- mum hourly electric output rate and maximum steam flow rate. When establishing fuel consump- tion specifications in terms of weight or volume, the minimum fuel quality based on Btu content shall be used for determining the basic design parameters for a coal-fired electric utility steam generating unit.

b.        Except as provided in subsection (3)(c), the basic design parameters for any process unit that is not at a steam electric generating facility are maximum rate of fuel or heat input,  maximum rate of material input, or maximum rate of product output. Combus- tion process units will typically use maximum rate of fuel input. For sources having multiple end prod- ucts and raw materials, the owner or operator should consider the primary product or primary raw mate- rial when selecting a basic design parameter.

c.         If the owner or operator believes the basic design parameters in subsections (3)(a) and (b) are not appropriate for a specific industry or type of process unit, the owner or operator may propose to the Director an alternative basic design parameters for the source’s process unit. If the Director approves of the use of an alternative basic design parameters, the Director shall issue a permit that is legally enforce- able that records such basic design parameters and requires the owner or operator to comply with such parameters.

d.        The owner or operator shall use credible informa- tion, such as results of historic maximum capability tests, design information from the manufacturer, or engineering calculations, in establishing the magni- tude of the basic design parameters specified in sub- sections (3)(a) and (b).

e.         If design information is not available for a process unit, then the owner or operator shall determine the process unit’s basic design parameters using the maximum value achieved by the process unit in the five-year period immediately preceding the planned activity.

f.         Efficiency of a process unit is not a basic design parameter.

g.        The replacement activity shall not cause the process unit to exceed any emission limitation, or opera- tional limitation that has the effect of constraining emissions, that applies to the process unit and that is legally enforceable.

4.        “Complete” means, in reference to an application for a permit or permit revision, that the application contains all the information necessary for processing the application.

5.        “Dispersion technique” means any technique that attempts to affect the concentration of a pollutant in the ambient air by any of the following:

a.         Using that portion of a stack that exceeds good engi- neering practice stack height;

b.        Varying the rate of emission of a pollutant according to atmospheric conditions or ambient concentrations of that pollutant; or

c.         Increasing final exhaust gas plume rise by manipu- lating 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 that increases the exhaust gas plume rise. This shall not include any of the following:

i.         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 gen- erating the gas stream.

ii.        The merging of exhaust gas streams under any of the following conditions:

(1)     The source owner or operator demon- strates that the facility was originally designed and constructed with the merged gas streams;

(2)     After July 18, 1985, the merging is part of a change in operation at the facility that includes the installation of pollution con- trols and is accompanied by a net reduc- tion in the allowable emissions of a pollutant, applying only to the emission limitation for that pollutant; or

Department of Environmental Quality – Air Pollution Control

(3)     Before July 8, 1985, the merging was part of a change in operation at the facility that included the installation of emissions con- trol equipment or was carried out for sound economic or engineering reasons. Where there was an increase in the emis- sion limitation or, in the event that no emission limitation was in existence prior to the merging, an increase in the quantity of pollutants actually emitted prior to the merging, the Department shall presume that merging was significantly motivated by an intent to gain emissions credit for greater dispersion. Absent a  demonstra- tion by the source owner or operator that merging was not significantly motivated by such intent, the Department shall deny credit for the effects of the merging in cal- culating the allowable emissions for the source.

iii.      Smoke management in agricultural or silvicul- tural prescribed burning programs.

iv.       Episodic restrictions on residential woodburn- ing and open burning.

v.        Techniques that increase final exhaust gas plume rise if the resulting allowable emissions of sulfur dioxide from the facility do not exceed 5,000 tons per year.

6.        “Existing emissions unit” is any emissions unit that is currently in existence and that is not a new emissions unit. A replacement unit is an existing emissions unit.

7.        “High terrain” means any area having an elevation of 900 feet or more above the base of the stack of a source.

8.        “Innovative control technology” means any system of air pollution control that has not been adequately demon- strated in practice but would have a substantial likelihood of achieving greater continuous emissions reduction than any control system in current practice, or of achieving at least comparable reductions at lower cost in terms of energy, economics, or nonair quality environmental impacts.

9.        “Low terrain” means any area other than high terrain.

10.     “Lowest achievable emission rate” (LAER) means, for any source, the more stringent rate of emissions based on one of the following:

a.         The most stringent emissions limitation that is con- tained in any implementation plan approved or pro- mulgated under sections 110 or 172 of the Act for the class or category of stationary source, unless the owner or operator of the proposed stationary source demonstrates that the limitation is not achievable; or

b.        The most stringent emissions limitation that is achieved in practice by the class or category of sta- tionary source. This limitation, when applied to a modification, means the lowest achievable emis- sions rate for the new or modified emissions units within the stationary source. The application of this term shall not permit a proposed new or modified stationary source to emit any pollutant in excess of the amount allowable under applicable standards of performance in Articles 9 and 11 of this Chapter.

11.     “Major source” means:

a.         Any stationary source located in a nonattainment area that emits, or has the potential to emit, 100 tons per year or more of any regulated NSR pollutant, except that the following thresholds shall apply in

areas subject to subpart 2, subpart 3 or subpart 4 of part D, Title I of the Act:

b.        Any stationary source located in an attainment or unclassifiable area that emits, or has the potential to emit, 100 tons per year or more of any regulated NSR pollutant if the source is classified as a Cate- gorical Source, or 250 tons per year or more of any regulated NSR pollutant if the source is not classi- fied as a Categorical Source;

c.         Any stationary source that emits, or has the potential to emit, five or more tons of lead per year;

d.        A major source that is major for VOC or nitrogen oxides shall be considered major for ozone; or

e.         The fugitive emissions of a stationary source shall

not be included in determining for any of the pur- poses of this Section whether it is a major stationary source, unless the source belongs to a section 302(j) category.

12.     “New emissions unit” means any emissions unit which is (or will be) newly constructed and which has existed for less than two years from the date such emissions unit first operated.

13.     “Plantwide applicability limitation” or “PAL” means an emission limitation that is based on the baseline actual emissions of all emissions units at the stationary source that emit or have the potential to emit the PAL pollutant, expressed in tons per year, for a pollutant at a major source, that is enforceable as a practical matter and estab- lished source-wide in accordance with this Section.

14.     “PAL allowable emissions” means “allowable emissions” as defined in R18-2-101, except that the allowable emis- sions for any emissions unit shall be calculated consider- ing any emission limitations that are enforceable as a practical matter on the emissions unit’s potential to emit.

15.     PAL effective date generally means the date of issuance of the PAL permit. However, the PAL effective date for an increased PAL is the date any emissions unit that is part of the PAL major modification becomes operational and begins to emit the PAL pollutant.

16.     “PAL effective period” means the period beginning with the PAL effective date and ending 10 years later.

17.     “PAL major modification” means any physical change in or change in the method of operation of the PAL source that causes it to emit the PAL pollutant at a level equal to or greater than the PAL.

18.     “PAL permit” means the permit issued by the Director that establishes a PAL for a major source.

Department of Environmental Quality – Air Pollution Control

19.     “PAL pollutant” means the pollutant for which a PAL is established at a major source.

20.     “Projected actual emissions” means:

a.         The maximum annual rate, in tons per year, at which an existing emissions unit is projected to emit a reg- ulated NSR pollutant during any 12-month period in the 60 calendar months following the date the unit resumes regular operation after the project, or in any 12-month period in the 120 calendar months follow- ing that date if the project involves increasing the design capacity or potential to emit of any emissions unit for that regulated NSR pollutant and full utiliza- tion of the unit would result in a significant emis- sions increase or a significant net emissions increase at the major source.

b.        In determining the projected actual emissions before beginning actual construction, the owner or operator of the major source:

i.         Shall consider all relevant information, includ- ing but not limited to, historical operational data, the company’s own representations, the company’s expected business activity and the company’s highest projections of business activity, the company’s filings with the county, state or federal regulatory authorities, and com- pliance plans under these regulations; and

ii.        Shall include fugitive emissions to the extent quantifiable;

iii.      Shall include emissions associated with start- ups and shutdowns, except emissions from a shutdown associated with a malfunction; and

iv.       Shall exclude, only for calculating any increase in emissions that results from the particular project, that portion of the unit’s emissions fol- lowing the project that an existing unit could have accommodated during the consecutive 24- month period used to establish the baseline actual emissions and that are also unrelated to the particular project, including any increased utilization due to product demand growth; or

c.         In lieu of using the method set out subsections (20)(b)(i) through (iv), the owner or operator may elect to use the emissions unit’s potential to emit, in tons per year.

21.    “Reconstruction” of sources located in nonattainment areas shall be presumed to have taken place if the fixed capital cost of the new components exceeds 50% of the fixed capital cost of a comparable entirely new stationary source, as determined in accordance with the provisions of 40 CFR 60.15(f)(1) through (3).

22.     “Replacement unit” means an emissions unit for which all the criteria listed in subsections (22)(a) through (d) are met. No creditable emission reductions shall be generated from shutting down the existing emissions unit that is replaced.

a.         The emissions unit is a reconstructed unit within the meaning of 40 CFR 60.15(b)(1), or the emissions unit completely takes the place of an existing emis- sions unit.

b.        The emissions unit is identical to or functionally equivalent to the replaced emissions unit.

c.         The replacement does not alter the basic design parameters of the process unit.

d.        The replaced emissions unit is permanently removed from the major source, otherwise permanently dis- abled, or permanently barred from operation by a

permit that is enforceable as a practical matter. If the replaced emissions unit is brought back into opera- tion, it shall constitute a new emissions unit.

23.     “Resource recovery project” means any facility at which solid waste is processed for the purpose of extracting, converting to energy, or otherwise separating and prepar- ing solid waste for reuse. Only energy conversion facili- ties that utilize solid waste that provides more than 50% of the heat input shall be considered a resource recovery project under this Article.

24.     “Significant emissions unit” means an emissions unit that emits or has the potential to emit a PAL pollutant in an amount that is equal to or greater than the significant level for that PAL pollutant, but less than the amount that would qualify the unit as a major emissions unit.

25.     “Significance levels” means the following ambient con- centrations for the enumerated pollutants:

Averaging Time
Pollutant	Annual	24-Hour	8-Hour	3-Hour	1-Hour
SO2	1 µg/m3	5 µg/m3		25 µg/m3
NO2	1 µg/m3
CO			0.5 mg/m3		2 mg/m3
PM10	1 µg/m3	5 µg/m3
PM2.5 Class I area	0.06 µg/m3	0.07 µg/m3
PM2.5 Class II area	0.3 µg/m3	1.2 µg/m3
PM2.5 Class III area	0.3 µg/m3	1.2 µg/m3
Except for the annual pollutant concentrations, the Department shall deem that exceedance of significance levels has occurred when the ambient concentration of the above pollutant is exceeded more than once per year at any one location. If the concentration occurs at a specific location and at a time when Arizona ambient air quality standards for the pollutant are not violated, the signifi- cance level does not apply.

26.     “Small emissions unit” means an emissions unit that emits or has the potential to emit the PAL pollutant in an amount less than the significant level for that PAL pollut- ant.

Historical Note

Adopted effective May 14, 1979 (Supp. 79-1). Amended

effective October 2, 1979 (Supp. 79-5). Former Section R9-3-401 renumbered without change as Section R18-2- 401 (Supp. 87-3). Section R18-2-401 renumbered to R18- 2-601. New Section R18-2-401 adopted effective November 15, 1993 (Supp. 93-4). Amended by final

rulemaking at 5 A.A.R. 4074, effective September 22, 1999 (Supp. 99-3). Typographical error corrected in R18- 2-401(9)(a) (Supp. 00-4). Amended by final rulemaking at 13 A.A.R. 1134, effective May 5, 2007 (Supp. 07-1). Amended by final rulemaking at 18 A.A.R. 1542, effec- tive August 7, 2012 (Supp. 12-2).