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The TCEQ has released formal guidance on the process for existing major sources of hazardous air pollutants (HAPs) to reclassify their site as an area source of HAP emissions. This guidance is a result of EPA's January 25, 2018 memo rescinding their "Once In, Always In" policy for Maximum Available Control Technology (MACT) Standards. EPA's memo states that a MACT source which is subject to a major source MACT rule which reduces it's potential to emit (PTE) such that it becomes an area source of HAP emission (10 tons per year (tpy) of any HAP and 25 tpy of aggregate HAP) will no longer be subject to the major source MACT rule.

However, since EPA did not provide detailed guidance for the mechanism by which a source could take advantage of this ruling, TCEQ has issued a step-by-step guide to be used in lieu of detailed guidance provided from the EPA. TCEQ's guidance details four conditions that must be met before the major source MACT and all applicable major source MACT requirements are no longer applicable. The steps are as follows:

  1. Obtain a federally enforceable PTE below the major source thresholds of 10 tpy of any single HAP and 25 tpy of total HAP.
  2. All necessary operating permit revisions have been issued to remove any conditions of the major source MACT rule.
  3. All physical or operational changes to reduce PTE to the federally enforceable limit below the major source MACT limits have been completed.
  4. Necessary records to demonstrate the federally enforceable PTE is below the major source MACT threshold are being maintained.

In addition, sites should ensure they continue to maintain records of compliance with the major source MACT rule for the period of time specified in the major source MACT rule or the operating permit, whichever is longer.

For assistance with your air permitting needs, contact the Trinity office nearest you by calling (800) 229-6655 for more information.