1. Whether a common-law claim for restoration seeking clean-up remedies that conflict with EPA-ordered remedies is a “challenge” to EPA’s cleanup jurisdictionally barred by § 113 of CERCLA.
2. Whether a landowner at a Superfund site is a “potentially responsible party” that must seek EPA’s approval under CERCLA § 122(e)(6) before engaging in remedial action, even if EPA has never ordered the landowner to pay for a cleanup.
3. Whether CERCLA preempts state common-law claims for restoration that seek cleanup remedies that conflict with EPA-ordered remedies.