40 C.F.R. § 49.152
Affected emissions units means the following emissions units, as applicable:
Allowable emissions means "allowable emissions" as defined in § 52.21(b)(16) of this chapter, except that the allowable emissions for any emissions unit are calculated considering any emission limitations that are enforceable as a practical matter on the emissions unit's potential to emit.
Begin construction means, in general, initiation of physical on-site construction activities on an emissions unit which are of a permanent nature. Such activities include, but are not limited to, installation of building supports and foundations, laying underground pipework and construction of permanent storage structures. With respect to a change in method of operations, this term refers to those on-site activities other than preparatory activities which mark the initiation of the change. The following preparatory activities are excluded: Engineering and design planning, geotechnical investigation (surface and subsurface explorations), clearing, grading, surveying, ordering of equipment and materials, storing of equipment or setting up temporary trailers to house construction management or staff and contractor personnel.
Commence construction means, as applied to a new minor stationary source or minor modification at an existing stationary source subject to this subpart, that the owner or operator has all necessary preconstruction approvals or permits and either has:
Emission limitation means a requirement established by the reviewing authority that limits the quantity, rate or concentration of emissions of air pollutants on a continuous basis, including any requirement relating to the operation or maintenance of a source to assure continuous emissions reduction and any design standard, equipment standard, work practice, operational standard or pollution prevention technique.
Enforceable as a practical matter means that an emission limitation or other standard is both legally and practicably enforceable as follows:
Environmental Appeals Board means the Board within the EPA described in § 1.25(e) of this chapter.
Indian country, as defined in 18 U.S.C. 1151 , means the following as applied to this program:
Indian governing body means the governing body of any Tribe, band or group of Indians subject to the jurisdiction of the United States and recognized by the United States as possessing power of self-government.
Minor modification at a major source means a modification at a major source that does not qualify as a major modification under § 49.167 or § 52.21 of this chapter, as applicable.
Minor NSR threshold means any of the applicability cutoffs for this program listed in Table 1 of § 49.153 .
Minor source means, for purposes of this rule, a source, not including the exempt emissions units and activities listed in § 49.153(c) , that has the potential to emit regulated NSR pollutants in amounts that are less than the major source thresholds in § 49.167 or § 52.21 of this chapter, as applicable, but equal to or greater than the minor NSR thresholds in § 49.153 . The potential to emit includes fugitive emissions, to the extent that they are quantifiable, only if the source belongs to one of the source categories listed in part 51, Appendix S, paragraph II.A.4(iii) or § 52.21(b)(1)(iii) of this chapter, as applicable.
Modification means any physical or operational change at a source that would cause an increase in the allowable emissions of a minor source or an increase in the actual emissions (based on the applicable test under the major NSR program) of a major source for any regulated NSR pollutant or that would cause the emission of any regulated NSR pollutant not previously emitted. Allowable emissions of a minor source include fugitive emissions, to the extent that they are quantifiable, only if the source belongs to one of the source categories listed in part 51, Appendix S, paragraph II.A.4(iii) or § 52.21(b)(1)(iii) of this chapter, as applicable. The following exemptions apply:
Potential to emit means the maximum capacity of a source to emit a pollutant under its physical and operational design. Any physical or operational limitation on the capacity of the source to emit a pollutant, including air pollution control equipment and restrictions on hours of operation or on the type or amount of material combusted, stored or processed, shall be treated as part of its design if the limitation or the effect it would have on emissions is enforceable as a practical matter. Secondary emissions, as defined at § 52.21(b)(18) of this chapter, do not count in determining the potential to emit of a source.
Reviewing authority means the Administrator or may mean an Indian Tribe in cases where a Tribal agency is assisting EPA with administration of the program through a delegation.
Startup of production is as defined at § 60.5430a .
Synthetic minor HAP source means a source that otherwise has the potential to emit HAPs in amounts that are at or above those for major sources of HAP in § 63.2 of this chapter, but that has taken a restriction so that its potential to emit is less than such amounts for major sources. Such restrictions must be enforceable as a practical matter.
Synthetic minor source means a source that otherwise has the potential to emit regulated NSR pollutants in amounts that are at or above those for major sources in § 49.167 , § 52.21 or § 71.2 of this chapter, as applicable, but that has taken a restriction so that its potential to emit is less than such amounts for major sources. Such restrictions must be enforceable as a practical matter.
True minor source means a source, not including the exempt emissions units and activities listed in § 49.153(c) , that emits or has the potential to emit regulated NSR pollutants in amounts that are less than the major source thresholds in § 49.167 or § 52.21 of this chapter, as applicable, but equal to or greater than the minor NSR thresholds in § 49.153 , without the need to take an enforceable restriction to reduce its potential to emit to such levels. That is, a true minor source is a minor source that is not a synthetic minor source. The potential to emit includes fugitive emissions, to the extent that they are quantifiable, only if the source belongs to one of the source categories listed in part 51, Appendix S, paragraph II.A.4(iii) or § 52.21(b)(1)(iii) of this chapter, as applicable.
40 C.F.R. §49.152