Hundreds of people have been lining up today in the ballroom of a Charlotte hotel to have their say on a new EPA proposal for regulating the toxic byproducts of coal-fired power planes. It's called "coal ash" and WFAE's Julie Rose reports the comments fall into three categories. First, there are the concerned citizens and environmental groups who want the strictest rules possible. Power companies often store coal ash in ponds near lakes and rivers. Duke Energy has two on Mountain Island Lake, Charlotte's main drinking source. "These aging coal ash ponds - one built in 1957 - are both still unlined, both are still leaching hazardous substances into the ground and contaminating our ground water - a fact documented by Duke Energy's own data," testified Bill Gupton of the local Sierra Club. Most of the 13 coal ash ponds in North Carolina belong to Duke Energy. The soil and groundwater contamination levels at those ponds are within current state limits but that could change with an EPA proposal to start regulating coal ash as a hazardous waste. Power companies nationwide would have to clean up and close their ash ponds. They say that will cost millions. "Power generation costs will increase in response to burdensome equipment retrofits and operating requirements," said Randy Melton of Tampa Electric. "Utility customers throughout the country will suffer significant rate increases." That's Randy Melton of Tampa Electric. Duke Energy testified at the hearing, too. All of the power companies that spoke say they prefer a less-stringent set of rules that would largely preserve the status quo, but with some additional monitoring requirements. The third category of public comment at the EPA hearing comes from people like Bill Black who make a living recycling coal ash for use in cement and construction. Black's company is called the SEFA Group. "Whatever you do," he told the EPA, "please, please don't give coal ash a stigma by calling it 'hazardous waste.'" "The vast majority of my company's customers that I have personally spoken to have told me that if the EPA designates fly ash as a hazardous material, they will discontinue the use of it in their concrete products," said Black. Duke Energy says about 45 percent of its coal ash is recycled. If that stopped, it would have a problem disposing of all that waste. Environmental advocates say power companies need to face up to the true cost of coal-fired power generation. The Charlotte hearing is the fourth of seven EPA public hearings on coal ash being held across the nation. The whole process is a result of the disaster in 2008 when a coal ash pond breached its dam and flooded a nearby community with toxic sludge.