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Tier I BACT (Best Available Control Technology) is a function of what similar facilities are deploying for a particular pollutant and is usually a function of time. Depending on if the permit is being filed for Minor versus Major NSR permit application, there are two main plans of an NSR permit:  State BACT and Federal BACT. The following typically trigger BACT:

  • Modification:  Any physical change in, or change in the method of operation of, a facility in a manner that increases the amount of any air contaminant emitted by the facility into the atmosphere or that results in the emission of any air contaminant not previously emitted.
  • Increase in allowable emissions
  • Incorporating a PBR into an NSR permit

Best Available Control Technology (BACT) is an air pollution control method for a new or modified facility that through experience and research has proven to be operational, obtainable, and capable of reducing or eliminating emissions from the facility. BACT is applied as part of a case-by-case review for all new or modified facilities, and BACT determinations are to be based on technical practicability and economic reasonableness.

In accordance with BACT guidance documents, the agency does not dictate what specific controls are required to meet the requirements for BACT. As such, the emissions reduction can be achieved through technology such as the use of add-on control equipment or by enforceable changes in production processes, systems, methods, or work practice, as determined by the owner or operator of the subject facilities.

There are three Tiers:

  • Tier I being the presumptive BACT (Best Available Control Technology)
  • Tier II is possible BACT based on similar source in another industry category
  • Tier III is top down analysis (similar to PSD)

So, when there is a presumptive (Tier I) BACT out there for a source type, in order to establish an exception to it, the permittee has to first make a case for why it is not applicable to the source in question because of the uniqueness of the process or the vent stream that it generates which has to be eventually controlled per BACT requirements. Once that has been established, the permittee can then go on and do either a Tier II analysis (where they look at similar vent streams at different processes) or conduct a Tier III analysis (primarily economic analysis) to establish BACT for the facility in question. Here are some examples where exceptions were made to Tier I BACT for source types where TCEQ had a presumptive BACT established.

BACT Case Studies that illustrate exception to Tier I BACT for affected facilities:

  • Establish NOx BACT for a steam generating unit (boiler) combusting a unique process waste stream in addition to natural gas at a chemical facility
  • Making an exception to Tier I NOx BACT for a turbine in LNG service as opposed to the presumptive BACT that had been established primarily for turbine used in electric generating facilities
  • Using Tier I BACT for a Cat Cracker vent stream to establish BACT for a process heater with catalyst regeneration at a chemical facility
  • Using a combination of RBLC, TX issued NSR permits, and NSPS to formulate NOx BACT for a furnace in a chemical production unit
  • Establish NOx BACT for TO that controls organic waste gas streams with high nitrogen content
  • Determine VOC BACT for an absorber that treats unique organic vent stream with a proprietary scrubbing material
  • Determine Catalyst change as VOC BACT for multiple process vents at a chemical process unit

TCEQ has tables that illustrate the latest BACT guidelines for each source type and by pollutant. If you have any questions or could use assistance with BACT, please contact your local Trinity office by calling (800) 229-6655 for more information.