Modification

Modification means a change to an existing SSI unit later than September 21, 2011 and that meets one of two criteria:
(1) The cumulative cost of the changes over the life of the unit exceeds 50-percent of the original cost of building and installing the SSI unit (not including the cost of land) updated to current costs (current dollars). To determine what systems are within the boundary of the SSI unit used to calculate these costs, see the definition of SSI unit.
(2) Any physical change in the SSI unit or change in the method of operating it that increases the amount of any air pollutant emitted for which section 129 or section 111 of the Clean Air Act has established standards.

Source

40 CFR § 62.16045

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Scoping language

Terms used but not defined in this subpart are defined in the Clean Air Act and 60.2 of this chapter.

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