Last week, the EPA finally took action to clarify the application of the “Maximum Achievable Control Technology (“MACT”) Hammer” to vacated MACT standards.  The MACT Hammer is the provision that requires existing sources to develop case-by-case MACT limits for hazardous air pollutants if EPA misses its deadline for promulgating a generally applicable MACT standard.  Recently, the vacatur of four MACT standards by the U.S. Court of Appeals for the D.C. Circuit has caused confusion over whether (and if so, when) the MACT Hammer applies following the vacatur of a MACT, given that EPA met the deadline and yet the standard no longer legally exists.  States and regulated facilities alike have looked to EPA for guidance on whether, and if so when, the MACT Hammer would “fall” on sources potentially covered by the vacated standards.  Given EPA’s recent efforts to promulgate a MACT standard for electric generating units (“EGUs”), there has also been significant concern over whether the MACT Hammer would apply to EGUs as well.

According to a proposed rule issued March 30th, EPA plans to require sources covered by a recently vacated MACT that is now past-due to submit permit applications for case-by-case MACT determinations within 90 days of the date EPA finalizes the rule, likely later this year.  However, according to EPA, the statutory provision creating the MACT Hammer (Section 112(j)) does not apply to coal- and oil-fired EGUs, a fact the proposed rule is intended to clarify.  In the preamble to the proposed rule, EPA explains that Section 112(j) only applies to source categories “initially listed” under Section 112 in 1992, and therefore does not apply to EGUs, which EPA listed later.  As such, the MACT Hammer cannot be used to impose case-by-case MACT limits on existing EGUs, regardless of whether EPA complies with the deadline for adopting an EGU MACT.