(U.S. Sup. Ct. decision in United States v. Atlantic Research Corp., 127 S. Ct. 2331 (2007) allowing private parties to recover environmental clean-up cost has overruled 9th Circuit’s prior opinion in Pinal Creek Group v. Newmont Mining Corp., 118 F.3d 1298 (9th Cir. 1997); potentially responsible parties under CERCLA may seek contribution and cost recovery from other potentially responsible parties).