For years now, the Kochs have stored piles of uncovered petroleum coke — petcoke, for short — at their KCBX Terminals along the Calumet River on the city’s south side. Because black petcoke dust from two 30-foot-high piles blows through nearby residential neighborhoods on windy days, causing health concerns, the city of Chicago issued an order requiring the Kochs to build storage sheds to contain the messy stuff by 2016. The federal Environmental Protection Agency also declared that the dust emanating from the petcoke piles is a violation of the Clean Air Act.