High levels of arsenic found in Charlotte, NC main source of drinking water

Posted on Oct 31, 2012 in Environment

Toxic elements found downstream from NC coal-ash ponds

by: Charlotte Business Journal by Susan Stabley, Staff Writer

Researchers have found high levels of arsenic at Mountain Island Lake, Charlotte’s main source of drinking water, downstream from Duke Energy Corp.’s coal-fired Riverbend Steam Station in Gaston County.

Pore water samples collected from lake sediment were taken during the summers of 2010 and 2011 by researchers from Duke University’s Nicholas School of the Environment. They found samples containing up to 250 parts per billion of arsenic — which the researchers says is roughly 25 times higher than the U.S. Environmental Protection Agency standards for drinking water, and nearly twice the agency’s standard for aquatic life.

The discovery is part of a study by the Nicholas School that found high levels of arsenic, selenium and other toxic elements in lakes and rivers across the state that are downstream from power plant “coal-ash” settling ponds.

About 600 power plants in the country produce about 130 million tons of coal ash and other coal-combustion residues every year during the energy-generation process. More than half of the waste is stored in settling ponds and landfills.

“In several cases, we found contamination levels that far exceeded U.S. Environmental Protection Agency guidelines for safe drinking water and aquatic life,” Avner Vengosh, the school’s professor of geochemistry and water quality, says in a statement released today.

The study was published in Environmental Science & Technology, a peer-reviewed journal. The Duke University team collected and analyzed more than 300 water samples from 11 lakes and rivers for the study. Samples with the highest levels were found in coal-ash pond effluents above Mountain Island Lake, in French Broad River in Asheville and in Hyco and Mayo lakes.

“We are saving the sky by putting in more scrubbers to remove particulates from power plant emissions,” Vengosh says. “But these contaminants don’t just disappear. Our study shows they remain in high concentrations in the solid waste residue and wastewater the coal-fired power plants produce. Yet there is no systematic monitoring or regulations to reduce water-quality impacts from coal-ash ponds because coal ash is not considered hazardous waste.”

Last week, a coalition of conservation groups asked the N.C. Environmental Management Commission to require Progress Energy Carolinas and Duke Energy Carolinas to clean up groundwater contaminated by old, unlined coal-ash lagoons at 14 coal-fired power plants. The Southern Environmental Law Center filed that request in the form of a legal complaint on behalf of the Cape Fear River Watch, Sierra Club, Waterkeeper Alliance, and Western North Carolina Alliance.

The EPA held a marathon, 13-hour hearing here in 2010 when it had launched a look into coal-ash regulations. The Charlotte Business Journal live-blogged from the hearing on proposed coal-ash regulations.

Coal ash is considered an “exempt waste” under an amendment to the Resource Conservation and Recovery Act. The residues are captured by pollution-control technologies, such as scrubbers. Emissions are “scrubbed” from coal-plant smokestacks in a process called flue gas desulfurization. The captured gas is then pumped into a limestone slurry.

Duke University researchers contend the process may increase the risk of downstream water contamination.

“Plants that used flue gas desulfurization often discharged wastewater with greater concentrations of selenium and other contaminants,” says the study’s lead author Laura Ruhl, assistant professor at the University of Arkansas at Little Rock.

Ruhl completed her doctorate studies in Vengosh’s lab this summer. The co-authors of study are Gary Dwyer, senior research scientist; Heileen Hsu-Kim, assistant professor of environmental engineering; and Grace Schwartz, a Ph.D. student in environmental engineering, at Duke University.