The Haw River, which Pittsboro draws from for the town's drinking water (File photo: Lisa Sorg)
The City of Burlington’s south wastewater treatment plant released toxic 1,4-Dioxane into the Haw River, test results show, and the contamination reached Pittsboro’s drinking water supply.
The Town of Pittsboro issued a press release at 9:30 Thursday night, reporting that on Monday the chemical was detected in treated drinking water at 11.9 parts per billion. The EPA has not established a maximum level of 1,4-Dioxane in drinking water, but has set a health advisory goal of 35 ppb. However, that level is far less protective than the goal set for the chemical in rivers and streams, which is just 0.35 ppb.
Since traditional drinking water treatment can’t remove 1,4-Dioxane, it’s difficult for utilities without expensive advanced systems to meet the 0.35 ppb goal.
“It appears that a significant quantity of 1,4 dioxane was released into the Burlington wastewater treatment system and discharged into the Haw River before routine testing could indicate the presence of the substance in their discharge,” Colby Sawyer, Pittsboro’s public information officer wrote.
1,4-Dioxane is a “probable” carcinogen, according to federal health authorities.
The City of Burlington released the slug of 1,4-Dioxane into the Haw River about a week earlier than it arrived in Pittsboro. On July 17, testing showed the concentration of 1,4-Dioxane leaving the Burlington south plant was 160 ppb. A day later, the level had decreased to 86.9 ppb, and by July 19, it was 57.8 ppb.
“When a release of this type occurs, most of the substance flows downstream together,” Sawyer wrote. “The dilution and speed of travel of this bulked substance, or slug, is based on how fast and at what volume the river is flowing.”
Burlington is 30 miles upstream of Pittsboro.
The chemical entered Burlington’s wastewater treatment plant via one of the City’s industrial customers, although that company has not been publicly identified.
In 2020, the Haw River Assembly, represented by the Southern Environmental Law Center, and the City of Burlington reached a memorandum of agreement to identify sources of 1,4-Dioxane and to reduce its discharge.
Treated water recently taken from the Haw had higher levels of the chemical than water in holding tanks, which were below 2 ppb.
Test samples taken in Pittsboro on Wednesday indicate that the concentration of 1,4 dioxane in the Town’s finished water continues to decrease. That indicates the slug of 1,4-Dioxane “has likely already passed the Town’s water intake, meaning that concentrations will continue to decrease,” according to Sawyer.
However Pittsboro’s water treatment plant is drawing only the minimally required amounts from the Haw to keep the water system functional. The town is encouraging water customers within, or serviced by, the Town of Pittsboro to conserve water by reducing or eliminating non-essential water uses. These uses include landscape irrigation, washing vehicles and houses, filling pools.
“These water conservation measures are voluntary actions our customers can take to assist our water plant staff; there is no danger of losing the Town’s water supply,” Sawyer wrote.
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