NCDEQ Division of Water Resources identifies elevated 1,4-dioxane levels in Asheboro’s WWTP’s wastewater

The North Carolina Department of Environmental Quality’s Division of Water Resources (DWR) has been notified of elevated 1,4-dioxane levels discharged from the City of Asheboro Wastewater Treatment Plant to Hasketts Creek, which drains into the Deep River within the Cape Fear River Basin. 

The U.S. Environmental Protection Agency has categorized 1,4-dioxane as a likely human carcinogen, or a substance that likely can cause cancer. 1,4-Dioxane is used for a variety of industrial purposes.

The Asheboro Wastewater Treatment Plant detected a concentration of 651 ppb of 1,4-dioxane in a sample it collected on Nov. 7. DEQ, using EPA toxicity calculations for lifetime exposure, has determined that the average monthly concentration of 1,4-dioxane in the Asheboro discharge safe for downstream water supplies is 22 ppb or less. DWR conducted additional sampling and is waiting to confirm the results. DWR has notified downstream drinking water utilities.

In August 2023, DWR included 1,4-dioxane limits in Asheboro’s National Pollutant Discharge Elimination System (NPDES) permit. In September 2024, the North Carolina Office of Administrative Hearings issued an order striking these limits from the permit. DEQ has appealed the ruling, and EPA has objected to the ruling’s removal of the 1,4-dioxane limits from the permit. 

Monitoring is ongoing at wastewater treatment plants in the Cape Fear River Basin to track 1,4-dioxane. 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.  

DWR has posted sampling data online: Cape Fear River Basin 1,4-Dioxane Wastewater Discharge Data.