"Existing facility" with reference to a stationary source means any apparatus of the type for which a standard is adopted in NAC 445B.001 to 445B.3689, inclusive, the construction or modification of which was commenced before the date on which the standard was proposed or any apparatus which could be altered in such a way as to be of that type.
Nev. Admin. Code § 445B.065
NRS 445B.210