Asheboro’s wastewater treatment plant has once again discharged elevated levels of 1,4-dioxane into a creek that drains into a river within the Cape Fear River Basin, according to the North Carolina Department of Environmental Quality.
The plant detected a concentration of 651 parts per billion, or ppb, of the chemical compound, one the U.S. Environmental Protection Agency has categorized as a likely human carcinogen, in a sample it collected Nov. 7 from Hasketts Creek, according to a DEQ release.
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Hasketts Creek drains into the Deep River, which converges with the Haw River to form the Cape Fear River.
Using the EPA’s toxicity calculations for lifetime exposure, DEQ “has determined that the average monthly concentration of 1,4-dixoane in the Asheboro discharge safe for downstream water supplies is 22 ppb or less,” the release states.
The department’s Division of Water Resources took additional sampling and is waiting to confirm results. Division officials have notified downstream drinking water utilities, which provide drinking water to some 900,000 North Carolinians.
Earlier this year, downstream water utilities were notified that sampling results by the state and Asheboro revealed 1,4-dixoane levels were more than 10 times higher than the average established as safe for downstream water supplies.
DEQ’s announcement Friday comes a little more than three weeks after the EPA hosted a public hearing in Asheboro regarding the agency’s objection to the city’s proposed permit that excludes an effluent discharge limit for 1,4-dioxane.
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All but one person who spoke at that hearing urged the EPA to uphold its objection to the proposed National Pollutant Discharge Elimination System, or NPDES, permit issued by the division.
DEQ issued an NPDES permit to the plant in August 2023 that included effluent discharge limits for 1,4-dioxane.
The city sued and, in September 2024, the North Carolina Office of Administrative Hearings struck the limits from the permit.
DEQ’s appeal of that ruling is pending in Wake County Superior Court.
“Monitoring is ongoing at wastewater treatment plants in the Cape Fear River Basin to track 1,4-dixoane,” according to the release. “Significant reductions have occurred at some wastewater treatment plants through a collaborative effort with the Environmental Management commission (EMC), DEQ and municipal operators. DEQ will continue to work with the EMC to seek additional ways to achieve reductions in 1,4-dioxane discharges.”
On Thursday, the EMC voted to push to a later date hearing proposed monitoring and minimization rules for 1,4-dixoane and per- and polyfluoroalkyl substances, or PFAS, from industrial users and dischargers.
The commission is not scheduled to meet again this year.
Sampling data is posted on the division’s website.
