The country’s largest electric company was ordered Monday to excavate coal ash from all of its North Carolina power plant sites, slashing the risk of toxic chemicals leaking into water supplies but potentially adding billions of dollars to the costs consumers pay.
Duke Energy Corp. must remove the residue left after decades of burning coal to produce electricity, North Carolina’s environmental agency said. The company had proposed covering some storage pits with a waterproof cap, saying that would prevent rain from passing through and carrying chemicals through the unlined bottoms and would provide a quicker and cheaper option.
Duke Energy said Monday the expanded excavation requirement could double its costs to about $10 billion. It had previously estimated the task would take up to 30 years to complete at all 14 current and former coal-burning plants in the state.
Coal ash contains toxic metals like mercury, lead and arsenic.
Monday’s decision affects six coal-burning plants still operating in North Carolina. Pits at eight other power plants around the state had previously been ordered excavated, with the ash to be stored away from waterways.