EPA to add new rule on power plant discharges

Duke Energy's Marshall power plant on Lake Norman would be affected by a new EPA rule on wastewater discharges.
Duke Energy's Marshall power plant on Lake Norman would be affected by a new EPA rule on wastewater discharges. dlaird@charlotteobserver.com

After decades of inaction, the federal government in September will release its second major rule affecting coal ash from power plants in less than a year.

Last December, the Environmental Protection Agency released the first federal rules on ash disposal. This month, the agency will set the first federal limits on toxic metals – mostly from ash – in wastewater discharges from power plants.

The rule is significant, but its reach will be limited. Most utilities, including Duke Energy, are moving to dry-handling of ash that avoids discharges. Ponds that store ash in wet form and drain to rivers and lakes are being phased out in North Carolina.

The hazards of ash leaped to public attention early last year with Duke’s spill into the Dan River. Many metals in ash, such as arsenic and mercury, accumulate in the environment for years once released.

Mercury can lower IQs of children exposed to it in fish. Arsenic can increase cancer risks. Selenium from a Duke power plant in Stokes County wiped out most of a local lake’s fish species in the 1970s.

Arsenic has been detected at the bottom of Charlotte’s main water source, Mountain Island Lake. “The last thing we need is to continue to put toxins in water,” Catawba Riverkeeper Sam Perkins said.

The nation’s 1,100 coal-fired power plants dump 5.5 billion pounds of wastewater into lakes and rivers each year – half of the toxic pollutants discharged by all industries. EPA is considering a range of options that would cut those releases by up to 2.6 billion pounds.

Duke says much of its work to comply with the ash disposal rule will help meet wastewater standards. Moving to dry-ash handling answers many of the requirements of the disposal rule, the company says.

Most of Duke’s coal units already have or are converting to dry-handling of lightweight fly ash. North Carolina’s Coal Ash Management Act requires all units to handle the heavier bottom ash in dry form, or retire, by 2019.

North Carolina’s coal ash law in some ways exceeds the federal rules, said staff attorney Pete Harrison of the Waterkeeper Alliance. But he said neither addresses ash ponds that are no longer in use, which environmental advocates say pose risks to groundwater.

“That’s a huge blind space in that regulation,” Harrison said. “No matter what option they end up going with, none will address the legacy ponds.”

North Carolina’s ash law applies to drained ponds and those covered by soil. And some inactive ponds are among the 20 in North Carolina that Duke has either been ordered or will voluntarily excavate.

The state Department of Environment and Natural Resources proposed new discharge permits for three Charlotte-area Duke plants – the retired Riverbend on Mountain Island Lake, Marshall on Lake Norman and Allen on Lake Wylie – in March. The EPA rule isn’t proposed to go into effect until 2017.

In addition to coal ash, the rule will cover power plant scrubbers that capture sulfur dioxide air emissions but release wastewater high in metals.

Duke this year set up a claims process for drinking water treatment systems harmed by bromide, which is released by its scrubbers, and has paid about $3.1 million to two cities. Bromide in water supplies can react with chlorine, which treatment systems use to disinfect drinking water, to form toxic trihalomethanes in drinking water.

The Marshall power plant – but not its scrubbers – is a suspect in the trihalomethanes found in Charlotte’s tap water last month. The chemicals likely came from calcium bromide, which Duke used to wash coal. The washing, which was halted, helped reduce releases of mercury into the air when the coal was burned.

Duke expects the upcoming wastewater rule to require special treatment systems for power plants with scrubbers.

Bruce Henderson: 704-358-5051, @bhender