February 15, 2023

CERCLA/RCRA Exemptions Removed From CAA Site Remediation MACT

EPA has removed the CERCLA/RCRA exemptions from the Part 63, Subpart GGGGG site remediation air toxics standard, effective December 22, 2022. [87 FR 78545] The agency proposed to remove both the exemptions and the “co-location” provisions on May 13, 2016. [81 FR 29821] However, EPA has retained the co-location requirement upon further consideration. For this final rule, new sources are those site remediations that commenced construction or reconstruction after May 13, 2016. Any new sources that would have been exempted under the CERCLA/RCRA exemptions must comply with Subpart GGGGG by December 22, 2022, or upon initial startup, whichever is later. Any existing sources must comply with the standard by June 24, 2024. [§§63.7882(d) and 63.7883(g)]

CERCLA/RCRA Exemptions

The CERCLA exemption shielded a site remediation from Subpart GGGGG regulation if the remediation was performed as a CERCLA remedial action or non-time-critical removal action. [formerly §63.7881(b)(2)] The RCRA exemption stated the same but for RCRA corrective action at a RCRA-permitted treatment, storage, and disposal facility. [formerly §63.7881(b)(3)] These exemptions were included in the original 2003 rule because EPA concluded CERCLA/RCRA remediation requirements were “functionally equivalent” to the HAP emission control requirements in Subpart GGGGG. Additionally, both programs require a public participation process and are subject to federal oversight and enforcement authority.

However, nothing in CAA Section 112 authorizes EPA to exempt certain sources from emission standards based on regulation under another statute. The agency thus concluded that despite a “functional equivalence,” no statutory authority exists for the exemptions. With the exemptions’ removal, EPA estimated 74 facilities would become subject to Subpart GGGGG. The majority of these will likely only be subject to administrative requirements, but 13 facilities are anticipated to have on-site remediation activities requiring emission controls. [87 FR 78553-4]

Co-location Condition

Section 63.7881(a)(2) states Subpart GGGGG applies only if the site remediation is co-located at a facility with at least one HAP-emitting source meeting the definition of an affected source under another Part 63 standard. The affected source does not need to be subject to the standard, it only needs to meet the affected source’s definition. Removing this provision would mean any site remediations with emissions above major source thresholds would become regulated, even if the source is not otherwise subject to another air toxics standard.

Not only does EPA lack data showing any site remediations are themselves major sources of HAP emissions, but removing the provision could inhibit emergency responders from taking the necessary steps to protect human health and the environment. Commenters opposed to EPA’s proposed removal of this exemption stated emergency scenarios could arise necessitating an immediate clean-up along a pipeline or transportation corridor, and having to make a Subpart GGGGG applicability determination would impede clean-up efforts. It is also possible any emergency responders or owner/operators would not have the CAA experience necessary to comply with the standard. Based on the lack of data and to avoid inhibiting site remediation in unusual or emergency circumstances, EPA decided to retain the co-location condition. [87 FR 78551-2]


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This document addresses issues of a general nature related to the federal RCRA regulations. Persons evaluating specific circumstances dealing with the RCRA regulations should review state and local laws and regulations, which may be more stringent than federal requirements. In addition, the assistance of a qualified professional should be enlisted to address any site-specific circumstances.