The Georgia Environmental Protection Division (EPD) issued the revised Guideline for Ambient Impact Assessment of Toxic Air Pollutant Emissions, effective March 2017. EPD’s goal in revising the guidance document which was originally approved for use on June 28, 1998 was to provide a more user-friendly and definitive guideline for facility owners to demonstrate that emissions of toxic air pollutants (TAP) will comply with Georgia Rules For Air Quality Control 391-3-1.02(2)(a)1 and 391-3-1.02(2)(a)3. The following changes have been implemented with the March 2017 revised guidance:
- Adds a definitive list of TAP with the 15 minute and long term (24 hour or annual) averaging rate Acceptable Ambient Concentrations (AACs) – If the pollutant is not in the table then it does not need to be considered in the air toxic demonstration. Previous guidance required applicant to search four different databases for toxicity information
- Adds Minimum Emission Rates (MER) for the purpose of excluding TAP modeling for low facility-wide emission rates – If the facility wide emissions are below the MER for a pollutant then no analysis is required for that pollutant
- Clarifies the requirements to demonstrate compliance with AACs (TAP assessment)
- Implements step-by-step instructions for conducting impact assessment of TAP
- Includes refined model check list
- Allows use of site-specific risk analysis if the maximum ground-level concentration (MGLC) found by dispersion analysis is greater than AAC
When is the assessment of TAP emissions required?
- A TAP assessment is required for:
- All new facilities that requires a State Implementation Plan (SIP) Permit and emit a pollutant listed in the TAP table;
- All existing facilities that are adding new equipment that require a SIP permit and emit a pollutant listed in the TAP table;
- All existing facilities that are modifying existing equipment that increases the emission of a pollutant listed in the TAP table;
- All existing facilities that are modifying existing equipment or making process changes that result in emission of a pollutant listed in the TAP table not previously emitted from the facility;
- In some cases a demonstration may be required for sources that have never demonstrated compliance with the AAC; and
- Case by case as determined by EPD.
- For a pollutant that has a facility-wide emission rate below the MER, no further analysis is required.
- For pollutant that has a facility-wide emission rate above the MER, further analysis is required.