(a) A new municipal waste combustion unit is a municipal waste combustion unit that meets either of two criteria:
(1) Commenced construction after August 30, 1999.
(2) Commenced reconstruction or modification after June 6, 2001.
(b) This subpart does not apply to your municipal waste combustion unit if you make physical or operational changes to an existing municipal waste combustion unit primarily to comply with the emission guidelines in subpart BBBB of this part. Such changes do not qualify as reconstruction or modification under this subpart.