Ohio EPA’s new guidance on Best Available Technology Effective October 1, 2013
Ohio EPA proposed revisions to its 2009 Best Available Technology (BAT) guidance and to the BAT rule itself, OAC 3745-31-05, in May of this year. After a comment period, however, Ohio EPA has moved forward to adopt only the proposed revisions to the Guidance, entitled BAT Requirements for Permits Issued On or After October 1, 2013. The agency has deferred taking any action to revise the BAT rule at this time, and will revisit that issue once it has completed the 5-year review of the other provisions of OAC Chapter 3745-31, as mandated by ORC §119.032. Ohio EPA has also deferred review of OAC 3745-31-03 (Exemptions and Permits by Rule) and 3745-31-33 (Site Preparation Activities Prior to Obtaining a Final PTI or PTIO) at this time.
Ohio EPA requires that air permits for the installation of new equipment or the modification of existing equipment include state of the art BAT controls or practices to minimize air pollution. Sources with the potential to emit less than 10 tons per year of any criteria pollutant or precursor are exempt from BAT, as are those sources specifically exempted by OAC 3745-31-03. In 2006, the Ohio legislature amended Ohio’s air pollution control act to codify BAT and to provide greater clarity as to what was required. At that time, four categories of “case-by-case” BAT were established: Work Practices, Source Design Characteristics/Design Efficiency, Raw Material Specifications or Throughput Limitations, and Monthly Allowable Emissions. The revised Guidance addresses the first two categories only.
Changes to Work Practice BAT determinations
In the past, work practice BAT determinations have almost universally been based on the establishment of an opacity limit and control measures to be used to ensure that opacity limit is met. The revised Guidance eliminates the opacity limit in most cases, while leaving in place the control measures to be performed at set periodic frequencies.
Changes to Source Design Characteristic/Design Efficiency based BAT determinations
Ohio EPA’s historic practice with respect to BAT has been to establish short term limits (e.g. lb/hr, gr/dscf, etc.) for most pollutants as part of defining BAT. The 2013 Guidance “limits the use of short term emission limits to only those cases where the air pollution source or control device was specifically designed to meet a certain emission rate for a specific pollutant.”  Thus, if an emissions source was not designed to meet a short term limit, the BAT determination would not contain a short term emission limit but would include an annual limit instead.
While companies will perhaps be happy to see fewer short term emission limits in their permits, the fact that BAT for certain types of operations will no longer include such limits may affect overall potential to emit (PTE) calculations for such sources. Ohio EPA gives the example of a permit for a baghouse, which is designed to meet 0.03 gr/dscf, incorporating that Source Design Characteristic as its BAT determination. Under the new guidance, the 0.03 gr/dscf value is not a limit or ongoing compliance obligations, so it cannot be used to determine PTE. Instead, the source would need to look to whatever SIP limit might be applicable to those emissions – in this case, OAC 3745-17-11(B)(1), Restrictions on Particulate Emissions from Industrial Processes, aka the Process Weight Rate rule. In most cases, relying upon the allowable emissions from this rule would result in significantly higher PTE than reliance upon the design value of 0.03 gr/dscf and may trigger the need to seek a synthetic minor permit restriction to avoid the applicability of other regulatory requirements.
 May 1, 2013 Memorandum from Ohio EPA to Interested Parties re: Proposed Changes to Ohio’s Best Available Technology Program.