EPA designated two per- and polyfluoroalkyl substances (PFAS)—perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), including their salts and structural isomers—as hazardous substances under CERCLA. 

EPA established requirements for legacy coal combustion residuals (CCR) surface impoundments, as well as CCR management units at active CCR facilities and at inactive CCR facilities with a legacy CCR surface impoundment.