Contaminants found in private wells near Duke Energy’s ash ponds close to Charlotte were also detected in wells not affected by the ponds.
The North Carolina Department of Environment and Natural Resources reported the results for the Allen power plant on Lake Wylie, the Marshall plant on Lake Norman and the Buck plant on the Yadkin River near Salisbury.
Tests of private wells near the power plants resulted in more than 200 homeowners being advised not to drink their water. Most are neighbors of the Allen and Buck plants.
DENR officials called the results only a part of the work that will help determine whether contaminants found in private wells are coming from coal ash or natural sources.
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The new results DENR reported came from 24 wells near the power plants but in locations that are not connected to the groundwater near the ash ponds. The wells are meant to show where contaminants occur naturally.
Owners of 20 of the 24 wells got health advisories warning them not to drink their water. Most of the advisories were based on levels of vanadium and hexavalent chromium, the same elements found in wells close to the ash ponds.
Near the Allen ash ponds, 123 of 128 well owners had received don’t-drink advisories by July 7. At Buck, 71 of 71 tested wells drew that advice, and at Marshall, 31 of 33.
“The new results validate what we and others have been saying – the constituents found in the water samples occur naturally at various levels across the state,” Duke said in a statement.
Duke and DENR called the results only a part of the work that will help determine whether contaminants found in private wells are coming from coal ash or natural sources.
Concentrations of naturally occurring metals and other constituents can vary widely within fairly short distances, the department said. Soil and rock chemistry, and well construction techniques, can also influence results.
More significant findings are expected in groundwater assessments that Duke and its consultants will report by Sept. 9 for each of the 14 coal-fired power plants in the state.
The assessments will depict the direction and flow of groundwater around the ash ponds. Assessments for four power plants have been filed, two of which Duke said showed groundwater flowing away from private wells.