Duke Energy is asking a judge to prevent citizens groups from taking part in any action that would make it clean up nearly three dozen coal ash pits in the state. The Department of Environment and Natural Resources filed a complaint against Duke last year, and several citizens groups got involved in the case, saying the pits polluted groundwater. But Duke filed a motion on Monday to remove the groups from the case. The motion comes nearly two months after a coal ash spill at a Duke plant coated 70 miles of the Dan River in toxic sludge.