Nothing in this section shall be deemed to affect the liability of a person under paragraph (1) or (2) of section 9607(a) of this title.
The Administrator has the authority, under section 9615 of this title, to promulgate additional regulations concerning this section.
The exemptions provided in this section shall not affect any concluded judicial or administrative action or any pending judicial action initiated by the United States prior to November 29, 1999.