DUKEVILLE, N.C. -- For more than 80 years, the Thomas family has lived on a farm that abuts three open-air pits containing 6.1 million tons of ash from the coal-fired boilers of Duke Energy's Buck Steam Station.
Built in 1926, the hulking plant towers over the Yadkin River an hour's drive from the Charlotte headquarters of the nation's largest electricity company.
Since 2011, Duke and North Carolina environmental regulators have known that groundwater samples taken from monitoring wells near the Thomases' home and others in Dukeville contained substances -- some that can be toxic -- exceeding state standards.
The state could have required Duke to implement a cleanup plan to prevent spreading contamination. That never happened, state regulators said, because they weren't certain whether coal ash production was to blame or if the substances were naturally occurring.
Those living near the plant were never warned and continued using well water for drinking, bathing and cooking. Now the Thomases and their neighbors wonder not only what's in their water, but whether it's harmed them or their children.
In the wake of a Feb. 2 coal ash spill at another Duke plant, state regulators, environmental activists and Duke officials have been testing the water supplies for some of the 150 homes in Dukeville.
The state and Duke said their tests found no significant problems. But the findings conflict with those of the environmental group Waterkeeper Alliance, whose tests show levels of some potentially toxic substances above state standards.
Coal ash is the byproduct left behind when coal is burned to generate energy. It contains a witch's brew of toxic substances, including arsenic, selenium, chromium, beryllium, thallium, mercury, cadmium and lead.
Though there are no known studies linking coal ash pits to adverse health effects, residents are worried nonetheless because of years of cancer diagnoses and other ailments, including several birth defects.
In the 1990s, the community made news after a radiologist reported finding nearly a dozen cases of brain cancer dating back years among those either working at Buck or living nearby. An ensuing study looked for links to electromagnetic radiation from power lines but found no connection. The lead researcher said other potential causes weren't examined.
In the Thomas family, 71-year-old Joanne Thomas said she had a pituitary tumor removed from the base of her brain in 1996. Her husband, Ron, long retired from a job where he worked with industrial chemicals, survived prostate cancer and is undergoing treatment to remove mercury, cadmium and selenium from his blood. Records show one of Ron's brothers died of a brain tumor at 51. Ron's great-nephew died of brain cancer at 37. Both also lived in Dukeville.
Richard Clapp, a nationally known epidemiologist who studies drinking-water contaminates, said that while such illnesses are "unlikely" a coincidence, it's impossible to point to a specific cause without further study.
While the families living in Dukeville want more studies, Duke Energy officials said they have seen no evidence those living near its ash pits are at any risk and insist that groundwater is flowing away from neighboring properties.
"If we had any indications that we see with concerns to your health, Duke Energy would be proactive," Duke spokesman Erin Culbert told some 50 residents who gathered at a volunteer fire department in May to discuss the ash pits.
Culbert told The Associated Press that the company's tests of some Dukeville residential wells confirm the wells are safe and "show no indication the plant's ash basins have influenced their water quality."
The February spill at Duke's power plant near Eden, 80 miles northeast, coated North Carolina's Dan River in toxic sludge and ignited debate about the safety of Duke's 33 coal-ash dumps across the state. Nationally, there are more than 1,100 such dumps.
With federal officials still debating rules to govern the treatment, storage and disposal of coal ash, regulation has largely been left up to individual states. In North Carolina, political pressure is building for new legislation that could require Duke to dig out the ash from unlined pits and move it to lined landfills.
Duke has agreed to remove ash from the Dan River site and three others. But the company is studying what to do with the other 10, including the Buck Steam Station. The pits at Buck, the oldest dating to the 1950s, are ringed by 14 monitoring wells that are sampled by Duke three times a year and tested at the company's lab for contamination.
Duke retired the last of its coal-burning furnaces at Buck last year, replacing them with boilers fired by natural gas.
Among the options Duke has proposed for Buck would be to drain its remaining ponds and leave the ash in place, covered with plastic sheeting and a layer of soil. If it is forced to move the ash from all its sites in the state, the company has warned that customers, not shareholders, would likely foot the $10 billion bill.
Groundwater-test results released by the North Carolina Department of Environment and Natural Resources after a public-records request show that since 2011, water coming out of the test wells failed to meet state standards on 226 readings out of more than 2,500 -- most commonly for high amounts of manganese and iron but also for some boron.
One monitoring well, about 20 feet from the Thomas property line and about 400 feet from the family's well, exceeded groundwater standards for chromium on all three tests in 2011. One reading was nearly three times the state standard, while the others were just above it.
With the chromium in particular, North Carolina Water Resources Division spokesman Susan Massengale said officials have been trying to determine whether the levels were from chromium occurring naturally in the environment or industrial processes.
Both Massengale and Culbert, the Duke spokesman, noted that the company's monitoring well near the Thomas farm has not detected any chromium at all since the 2011 readings.
However, samples taken in March, April and May by the Waterkeeper Alliance from 15 wells used by the families and from seepage on the Thomas family's land contained chromium levels that exceeded limits. Wells at some of the homes exceeded state groundwater standards for total chromium, lead, iron and manganese.
Duke responded with the results of its own tests of samples collected in May from eight homes in Dukeville. With the exception of the Thomases, the homes the state and Duke tested were not the same ones the Waterkeeper Alliance tested earlier.
The company reported that state groundwater standards for zinc was exceeded at one home. Duke's testing also found trace amounts of chromium-6 in five of the eight wells, but Culbert said those findings were "extremely low."
Information for this article was contributed by Alex Sanz of The Associated Press.
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