The North Carolina Department of Environmental Quality’s Division of Water Resources (DWR) has been informed of elevated 1,4-dioxane levels discharged from the City of Asheboro Wastewater Treatment Plant (WWTP) to Hasketts Creek, which drains to the Deep River within the Cape Fear River Basin.
1,4-Dioxane is categorized by the EPA as a likely human carcinogen, or a substance that likely can cause cancer. See EPA’s Risk Evaluation for 1,4-dioxane. 1,4-Dioxane is used for a variety of industrial purposes.
DWR staff notified downstream drinking water utilities after Asheboro WWTP reported the elevated 1,4-dioxane levels on May 3. Utilities notified included the City of Sanford, Fayetteville Public Works Commission, Brunswick County and the Cape Fear Public Utility Authority in Wilmington.
The Asheboro WWTP detected a concentration of 826 parts per billion (ppb) from their discharge, collected on April 25. DWR detected a 1,4-dioxane concentration of 730 ppb in a sample collected from Asheboro WWTP’s discharge on the same day. DEQ, using EPA toxicity calculations for lifetime exposure, has determined that the average monthly 1,4-dioxane concentration protective of downstream water supplies is about 22 ppb for the Asheboro discharge.
The concentrations of 1,4-dioxane represent results of "grab samples," or wastewater samples taken at a single point in time by the facility and DWR. For 1,4-dioxane, the grab samples are performed using an U.S. Environmental Protection Agency-certified test method.
Monitoring is also being performed at other wastewater treatment plants identified to have 1,4-dioxane in their discharge to the Cape Fear River Basin, including Burlington, Greensboro, High Point and Reidsville.
DWR has posted sampling data online: Cape Fear River Basin 1,4-Dioxane Wastewater Discharge Data.