While environmental groups are cheering a May 4 Environmental Protection Agency proposal to regulate fly ash, utilities are concerned that potential designation of the material as a hazardous waste could prove costly. Photo: AP/Wideworld Liners would be required in coal-ash ponds to avert accidents like the disaster in 2008. The draft proposal would regulate for the first time coal ash under the Resource Conservation and Recovery Act (RCRA). Under the proposal, coal plants would be required to retrofit existing impoundments, which typically store the ash in liquid form, with composite liners. Enforcing the Regulation The more than 500-page proposal outlines