DEQ notifies water systems of elevated 1,4-dioxane levels in Asheboro’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 into Hasketts Creek, which empties 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 an industrial chemical used for a variety of purposes. It is a byproduct of certain plastics manufacturing processes. 

The Asheboro Wastewater Treatment Plant detected a concentration of 2,010 parts per billion (ppb) of 1,4-dioxane in a sample collected on July 10. 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.  

As part of its regular procedures, DWR sent a notification of the elevated levels to downstream drinking water utilities, including Bladen Bluffs Water System, Brunswick County, Cape Fear Public Utility Authority, the City of Dunn, the Fayetteville Public Works Commission, Harnett Regional Water, International Paper Co., Pender County, Pilgrim’s Pride Water System and the City of Sanford. 

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 appealed the ruling, and EPA objected to the ruling’s removal of the 1,4-dioxane limits from the permit. On Feb. 5, the Wake County Superior Court reversed the Office of Administrative Hearings order and held that the permit limits were properly included in the permit. Asheboro has appealed the decision. The limits are stayed until the case can be heard by the Court of Appeals. 

DEQ continues to monitor the levels of 1,4-dioxane discharged by wastewater treatment plants in the Cape Fear River Basin. Significant reductions have occurred at one wastewater treatment plant through a collaborative effort with municipal operators. DEQ continues to work with the remaining municipal operators.