|(a) Where a person can demonstrate that an affected unit cannot attain the applicable requirements of §117.105 of this title (relating to Emission Specifications for Reasonably Available Control Technology (RACT)) or the carbon monoxide (CO) or ammonia specifications of §117.110(c) of this title (relating to Emission Specifications for Attainment Demonstration), the executive director may approve emission specifications different from §117.105 of this title or the CO or ammonia specifications in §117.110(c) of this title for that unit. The executive director: (1) shall consider on a case-by-case basis the technological and economic circumstances of the individual unit; (2) shall determine that such specifications are the result of the lowest emission limitation the unit is capable of meeting after the application of controls to meet the nitrogen oxides emission specifications of §117.105 or §117.110 of this title, as applicable; and (3) in determining whether to approve alternative emission specifications, may take into consideration the ability of the plant where the unit is located to meet emission specifications through plant-wide averaging at maximum capacity. (b) Any owner or operator affected by the executive director's decision to deny an alternative case specific emission specification may file a motion to overturn the executive director's decision. The requirements of §50.139 of this title (relating to Motion to Overturn Executive Director's Decision) apply. Executive director approval does not necessarily constitute satisfaction of all federal requirements nor eliminate the need for approval by the United States Environmental Protection Agency in cases where specified criteria for determining equivalency have not been clearly identified in applicable sections of this division (relating to Beaumont-Port Arthur Ozone Nonattainment Area Major Sources).