SPOKANE, Wash. (AP) — A federal appeals court has ruled against Union Pacific railroad in a case involving cleanup of mining pollution in Idaho's Silver Valley. The 9th U.S. Circuit Court of Appeals this week reversed a lower court decision that had dismissed a lawsuit by Asarco against the railroad, and the case is now headed to trial. Asarco wants the railroad to pay some of the costs of cleaning up mining pollution in the Superfund site in the Silver Valley. Asarco has already paid $480 million to help clean up a century of mining pollution.

Union Pacific constructed rail lines to haul silver and other metals across the Silver Valley. The railroad contended that a settlement agreement with Asarco had resolved the issue. But the appeals court found that the agreement was ambiguous.