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Tuesday, December 7, 2010
News / Biz Years after coal-ash spill, Duke scientists study ongoing hazards
Posted By Rhiannon Fionn-Bowman on Tue, Dec 7, 2010 at 1:01 PM
Humans are a funny species. Like felines, if we can see something we often are able to convince ourselves it doesn't exist or impact our lives. Look no further than the two wars in Iraq and Afghanistan, and the one we're kinda-sorta involved with in Korea. No one's dying and nothing is blowing up stateside, so the wars often aren't on our mind.
Coal ash is something we produce all day, every day by simply using electricity; because we don't see it, we don't think about it. It's a waste product, and around these parts we store it in huge ponds, held in place by earthen dams.
The four unlined coal ash ponds near Charlotte, all owned by Duke Energy, drain into the Catawba River's lakes (Norman, Mountain Island and Wylie). This makes monitoring the ponds, and the heavy-metal-laced waste discharged from them, critical since we get our drinking water from the Catawba ... and since we know the discharge includes things like arsenic, which flows into Mountain Island Lake at the rate of one to three pounds per day.
In good news, the same Duke University scientist, Avner Vengosh, whose team studied the aftermath of the now two-year-old Tennessee coal ash spill, recently sampled the sediment in Mountain Island Lake — where 80 percent of our drinking water comes from. Specifically, he's studying how coal ash impacts the river. (He took the samples when he was in town for the EPA's hearing on their proposed coal ash regulations where he spoke out in favor of categorizing the waste as hazardous.)
While we await the results of his sampling trip to the Q.C. and the EPA's decision on coal ash's classification, here's a snippet from Chemical and Engineering News about what Dr. Vengosh discovered in Tennessee (you can purchase access to the full study here):
For their current report, the team collected over 220 surface water and sediment samples during an 18-month period of TVA's clean up. They measured concentrations of five leachable coal ash contaminants, including arsenic and selenium. The researchers found that anaerobic bacteria in the sediments produce conditions that reduce arsenic from the common pentavalent form to the more-toxic trivalent form, As3+. Meanwhile, selenium leeches out of these anoxic sediments and migrates to the more-oxygenated surface water.EPA's testing protocol does not predict these findings because it does not consider redox chemistry, explained co-author Helen Hsu-Kim: "The test is only concerned with acid-induced leaching." So it underestimates risks from arsenic under anaerobic disposal conditions, Vengosh says.
The team detected the highest contaminant levels near the spill site in a cove, which received a flowing waste stream during the spill. Given its isolation from the rest of the river, this cove concentrated ash pollutants, whereas in downstream areas with more water exchange, pollutant levels were more diluted. While surface water concentrations of selenium were high only in the cove, As3+ levels were high in sediments throughout the 300-acre spill site and surrounding watershed, Vengosh says.
Read the entire article, by Charles Schmidt, here.
Meanwhile, the coal ash dredged in Tennessee is being hauled to Perry County, Ala., a poor, rural area of the state. Here's the trailer for a documentary about the county's new toxic resident:
Rhiannon "Rhi" Bowman is an independent journalist who contributes snarky commentary on Creative Loafing's CLog blog four days a week in addition to writing for several other local media organizations. To learn more, click the links or follow Rhi on Twitter.
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