Asarco is appealing to federal regulators in its dispute with Union Pacific over lead pollution along railroad lines because it wants to make sure the $1.8 billion it has paid for cleanups is effective.
The Tucson, Arizona, based lead and copper mining company said Monday it filed a petition with the Surface Transportation Board seeking to reevaluate a 2001 decision allowing Union Pacific to abandon certain rail lines in southeast Missouri.
Asarco lawyer Gregory Evans says the railroad used rock from lead mines in ballast for its rail lines and some ore fell out of trains.
Union Pacific officials didn't immediately respond Tuesday, but they have fought Asarco's previous pollution allegations.
Asarco and Union Pacific are engaged in lawsuits related to lead contamination concerns in southeast Missouri, Omaha and Idaho.