§ 51.1

Definitions.

As used in this part, all terms not defined herein shall have the meaning given them in the Act:

(a) "Act" means the Clean Air Act (42 U.S.C. 1857-18577, as amended by Pub. L. 91-604, 84 Stat. 1676).

(b) "Administrator" means the Administrator of the Environmental Protection Agency (EPA) or his authorized representative.

(c) "Primary standard" means a national primary ambient air quality standard promulgated pursuant to section 109 of the Act.

(d) "Secondary standard" means a national secondary ambient air quality standard promulgated pursuant to section 109 of the Act.

(e) "National standard" means either a primary or a secondary standard.

(f) "Owner or operator" means any person who owns, leases, operates, controls, or supervises a facility, building, structure, or installation which directly or indirectly results or may result in emissions of any air pollutant for which a national standard is in effect.

(g) "Local agency" means any local government agency, other than the State agency, which is charged with the responsibility for carrying out a portion of a plan.

(h) "Regional Office" means one of the ten (10) EPA Regional Offices.

(i) "State agency" means the air pollution control agency primarily responsible for development and implementation of a plan under the Act.

(j) “Local agency" means any air pollution control agency other than a State agency, which is charged with responsibility for carrying out a portion of a plan.

(k) "Point source" means the following:

(1) For particulate matter, sulfur oxides, carbon monoxide, hydrocarbons, and nitrogen dioxide

(i) Any stationary source the actual emissions of which are in excess of 90.7 metric tons (100 tons) per year of the pollutant in a region containing an area whose 1970 "urban place" population, as defined by the U.S. Bureau of the Census, was equal to or greater than 1 million;

(ii) Any stationary source the actual emissions of which are in excess of 22.7 metric tons (25 tons) per year of the pollutant in a region containing an area whose 1970 "urban place" population, as defined by the U.S. Bureau of the Census was less than 1 million; or

(iii) Without regard to amount of emissions, stationary sources such as those listed in Appendix C to this part.

(2) For lead, any stationary source the actual emissions of which are in excess of 4.54 metric tons (5 tons) per year of lead or lead compounds measured as elemental lead.

(1) "Area source" means any small residential, governmental, institutional, commercial, or industrial fuel combustion operations: Onsite solid waste disposal facility; motor vehicles, air

craft, vessels, or other transportation facilities; or other miscellaneous sources such as those listed in Appendix D to this part, as identified through inventory techniques similar to those described in: "A Rapid Survey Technique for Estimating Community Air Pollution Emissions," Public Health Service Publication No. 999AP-29, October 1966.

(m) "Region" means (1) an air quality control region designated by the Secretary of Health, Education, and Welfare or the Administrator, (2) any area designated by a State agency as an air quality control region and approved by the Administrator, or (3) any area of a State not designated as an air quality control region under paragraph (m) (1) or (2) of this section.

(n) "Control strategy" means a combination of measures designated to achieve the aggregate reduction of emissions necessary for attainment and maintenance of a national standard, including, but not limited to, measures such as:

(1) Emission limitations.

(2) Federal or State emission charges or taxes or other economic incentives or disincentives.

(3) Closing or relocation of residential, commercial, or industrial facilities.

(4) Changes in schedules or methods of operation of commercial or industrial facilities or transportation systems, including, but not limited to, shortterm changes made in accordance with standby plans.

(5) Periodic inspection and testing of motor vehicle emission control systems, at such time as the Administrator determines that such programs are feasible and practicable.

(6) Emission control measures applicable to in-use motor vehicles, including, but not limited to, measures such as mandatory maintenance, installation of emission control devices, and conversion to gaseous fuels.

(7) Measures to reduce motor vehicle traffic, including, but not limited to, measures such as commuter taxes, gasoline rationing; parking restrictions, or staggered working hours.

(8) Expansion or promotion of the use of mass transportation facilities

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through measures such as increases in the frequency, convenience, and passenger-carrying capacity of mass transportation systems or providing for special bus lanes on major streets and highways.

(9) Any land use or transportation control measures not specifically delineated herein.

(10) Any variation of, or alternative to, any measure delineated herein.

(11) Control or prohibition of a fuel or fuel additive used in motor vehicles, if such control or prohibition is necessary to achieve a national primary or secondary air quality standard and is approved by the Administrator under section 211(c)(4)(C) of the Act.

(o) "Reasonably available control technology" means devices, systems, process modifications, or other apparatus or techniques, the application of which will permit attainment of the emission limitations set forth in Appendix B to this part, provided that Appendix B to this part is not intended, and shall not be construed, to require or encourage State agencies to adopt such emission limitations without due consideration of (1) the necessity of imposing such emission limitations in order to attain and maintain a national standard, (2) the social and economic impact of such emission limitations, and (3) alternative means of providing for attainment and maintenance of such national standard.

(p) "Compliance schedule" means the date or dates by which a source or category of sources is required to comply with specific emission limitations contained in an implementation plan and with any increments of progress toward such compliance.

(q) "Increments of progress" means steps toward compliance which will be taken by a specific source, including:

(1) Date of submittal of the source's final control plan to the appropriate air pollution control agency;

(2) Date by which contracts for emission control systems or process modifications will be awarded; or date by which orders will be issued for the purchase of component parts to accomplish emission control or process modification;

(3) Date of initiation of on-site construction or installation of emission control equipment or process change;

(4) Date by which on-site construction or installation of emission control equipment or process modification is to be completed; and

(5) Date by which final compliance is to be achieved.

(r) "Transportation control measure" means any measure, such as reducing vehicle use, changing traffic flow patterns, decreasing emissions from individual motor vehicles, or altering existing modal split patterns that is directed toward reducing emissions of air pollutants from transportation sources.

(s) "Vehicle trip" means any movement of a motor vehicle from one location to another that results in the emission of air pollutants by the motor vehicle.

(t) "Trip type" means any class of vehicle trips possessing one or more characteristics (e.g., work, nonwork; peak, off-peak; freeway, nonfreeway) that distinguish vehicle trips in the class from vehicle trips not in the class.

(u) "Vehicle type" means any class of motor vehicles (e.g., precontrolled, heavy duty vehicles, gasoline powered trucks) whose emissions characteristics are significantly different from the emissions characteristics of motor vehicles not in the class.

(v) "Traffic flow measure" means any measure, such as signal light synchronization, freeway metering and curbside parking restrictions, that is taken for the purpose of improving the flow of traffic and thereby reducing emissions of air pollutants from motor vehicles.

(w) "Roadway type" means any class of roadway facility that can be broadly categorized as to function and assigned average speed and capacity values, e.g., expressway, arterial, collector, and local.

(x) "Time period" means any period of time designated by hour, month, season, calendar year, averaging time, or other suitable characteristics, for which ambient air quality is estimated. (y) "Variance" means the temporary deferral of a final compliance date for an individual source subject to an ap

proved regulation, or a temporary change to an approved regulation as it applies to an individual source.

(z) "Emission limitation" and "emission standard" mean a requirement established by a State, local government, or the Administrator which limits the quantity, rate, or concentration of emissions of air pollutants on a continuous basis, including any requirements which limit the level of opacity, prescribe equipment, set fuel specifications, or prescribe operation or maintenance procedures for a source to assure continuous emission reduction.

(aa) "Capacity factor" means the ratio of the average load on a machine or equipment for the period of time considered to the capacity rating of the machine or equipment.

(bb) "Excess emissions" means emissions of an air pollutant in excess of an emission standard.

(cc) "Nitric acid plant" means any facility producing nitric acid 30 to 70 percent in strength by either the pressure or atmospheric pressure process.

(dd) "Sulfuric acid plant" means any facility producing sulfuric acid by the contact process by burning elemental sulfur, alkylation acid, hydrogen sulfide, or acid sludge, but does not inIclude facilities where conversion to sulfuric acid is utilized primarily as a means of preventing emissions to the atmosphere of sulfur dioxide or other sulfur compounds.

(ee) "Fossil fuel-fired steam generator" means a furnace or boiler used in the process of burning fossil fuel for the primary purpose of producing steam by heat transfer.

(ff) "Stack" means any point in a source designed to emit solids, liquids, or gases into the air, including a pipe or duct but not including flares.

(gg) "A stack in existence" means that the owner or operator had (1) begun, or caused to begin, a continuous program of physical on-site construction of the stack or (2) entered into binding agreements or contractual obligations, which could not be cancelled 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.

(hh) "Dispersion technique" means 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 by addition of a fan or reheater to obtain a less stringent emission limitation. The preceding sentence does not 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; or (3) combining the exhaust gases from several stacks into one stack.

(ii) "Good engineering practice (GEP) stack height" means the greater of;

(1) 65 meters;

(2)(i) For stacks in existence on January 12, 1979 and for which the owner or operator had obtained all applicable preconstruction permits or approvals required under this Parts 51 and 52 of this Title 40, H,= 2.5H

H,

H,

(ii) for all other stacks,

=

H+1.5L, where

good engineering practice stack height, measured from the ground-level elevation at the base of the stack,

H-height of nearby structure(s) measured from the ground-level elevation at the base of the stack,

L= lesser dimension (height or projected width) of nearby structure(s);

(3) The height demonstrated by a fluid model or a field study approved by the reviewing agency, which enIsures that the emissions from a stack do not result in excessive concentrations of any air pollutant as a result of atmospheric downwash, wakes, or eddy effects created by the source itself, structures, or terrain obstacles.

(jj) "Nearby" as used in § 51.1(ii)(2) is that distance up to five times the lesser of the height or the width dimension of a structure but not greater than 0.8 km (one-half mile). The height of the structure is measured