“Commence operation” means to begin any mechanical, chemical, or electronic process, including, with regard to a unit, start-up of a unit's combustion chamber.

Source. #9283, INTERIM, eff 10-1-08, EXPIRED: 3-30-09 New. #9444, eff 4-3-09; ss by #10468, eff 1-1-14 (from Env-A 4602.31); ss by #12967, eff 1-1-20 (from Env-A 4602.33)