On February 8, 2024, EPA published a proposed rule to amend its regulation under the Resource Conservation and Recovery Act (RCRA) by adding nine specific per-and polyfluoroalkyl substances (PFAS), their salts, and their structural isomers, to its list of hazardous constituents in 40 CFR part 261 Appendix VIII. These nine PFAS are perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorobutanesulfonic acid (PFBS), hexafluoropropylene oxide-dimer acid (HFPO-DA or GenX), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), perfluorodecanoic acid (PFDA), perfluorohexanoic acid (PFHxA), and perfluorobutanoic acid (PFBA). As a result of this proposed rule, if finalized, these PFAS would be among the hazardous constituents expressly identified for consideration in RCRA treatment, storage and disposal facility assessments and, where necessary, further investigation and cleanup of these facilities through the RCRA corrective action process. EPA has provided a 60-day public comment period for this proposed rule. Following publication of the proposed rule, EPA has conducted outreach activities and responded to public inquiries on the proposal.  The outreach activities included the following: (1) Webinar for the Association of State and Territorial Solid Waste Management Officials (ASTSWMO) on February 21, 2024 and (2) a presentation to a Tribal PFAS Working Group on March 14, 2024.  These presentations are available in the docket for the proposed rule (Docket ID Number EPA-HQ-OLEM-2023-0278).  The 60-day comment period for the proposed rule ended on April 8, 2024.