[Code of Federal Regulations]
[Title 40, Volume 9]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR63.73]

[Page 90-91]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 63--NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES--Table of Contents
 
    Subpart D--Regulations Governing Compliance Extensions for Early 
                 Reductions of Hazardous Air Pollutants
 
Sec. 63.73  Source.

    (a) An alternative emission limitation may be granted under this 
subpart to an existing source. For the purposes of this subpart only, a 
source is defined as follows:
    (1) A building structure, facility, or installation identified as a 
source by the EPA in appendix B of this part;
    (2) All portions of an entire contiguous plant site under common 
ownership or control that emit hazardous air pollutants;
    (3) Any portion of an entire contiguous plant site under common 
ownership or control that emits hazardous air pollutants and can be 
identified as a facility, building, structure, or installation for the 
purposes of establishing standards under section 112(d) of the Act; or
    (4) Any individual emission point or combination of emission points 
within a contiguous plant site under common control, provided that 
emission reduction from such point or aggregation of points constitutes 
a significant reduction of hazardous air pollutant emissions of the 
entire contiguous plant site.
    (b) For purposes of paragraph (a)(4) of this section, emissions 
reductions are considered significant if they are made

[[Page 91]]

from base year emissions of not less than:
    (1) A total of 10 tons per year of hazardous air pollutants where 
the total emissions of hazardous air pollutants in the base year from 
the entire contiguous plant site is greater than 25 tons per; or
    (2) A total of 5 tons per year of hazardous air pollutants where the 
total emissions of hazardous air pollutants in the base year from the 
entire contiguous plant site is less than or equal to 25 tons per year.