This story has been corrected. Greensboro told Policy Watch today that they do not believe Shamrock Environmental is the source of the contamination. The data provided by the Town of Pittsboro did not account for dilution factors in Greensboro.
Pittsboro’s drinking water took another hit of 1,4-Dioxane last week, which the town attributes to an “additional slug of contamination coming from Greensboro” on July 6, according to a press release today.
As Policy Watch reported, on June 30, the City of Greensboro illegally discharged levels of of 1,4-Dioxane 20 times higher than EPA recommended levels from its TZ Osborne wastewater treatment plant into the South Buffalo Creek, a tributary of the Haw River, according to a NC Department of Environmental Quality press release. Pittsboro sources its drinking water from the Haw River.
1,4-Dioxane is a toxic chemical used in degreasers that the EPA has classified as a likely carcinogen. There is no regulatory standard for 1,4-Dioxane, but the EPA has set a health advisory goal of 35 parts per billion for drinking water, which equals a 1-in-10,000 lifetime excess cancer risk. The surface water goal is more stringent, at 0.35 ppb, a 1-in-1 million lifetime excess cancer risk.
Testing results announced by the Town of Pittsboro show that on July 6, levels of 1,4-Dioxane in raw water — straight from the Haw River — ranged from 26.5 parts per billion to 93.6 ppb. Treated drinking water at two sources were also elevated: Chatham Forest, 66.8 ppb and the water tank, 21. 7 ppb. Treated water from the Horton tank was 1.71 ppb.
These levels are above those on July 2 when raw water contained levels of 1,4-Dioxane at 76.5 parts per billion and treated drinking water showed levels of less than 1.25 ppb.
Meanwhile, upstream Shamrock Environmental test results showed that its mixed effluent into the TZ Osborne wastewater treatment plan on July 6 and 8 reached 98.8 ppb. A “flume grab” — before Shamrock’s wastewater had been mixed — measured 466 ppb.
However, City of Greensboro spokesman Elijah Williams said Shamrock Environmental is not the source of the contamination. Accounting for dilution factors, Shamrock’s levels would need to have been much higher for it to be responsible for this spill. Shamrock Environmental is in the waste management business, including tanker cleaning services. It was responsible for a previous spill in 2019, but Greensboro has recently ruled out the company in this incident.
Although 1,4-Dioxane is extremely difficult to remove from drinking water using conventional treatments, the Town of Pittsboro is refreshing water in their stored tanks with better-quality finished water to dilute and flush the contamination.
The TZ Osborne Wastewater Treatment Plant in Greensboro receives effluent from both residential and industrial customers in Guilford County.
Pittsboro officials in a press release said that recent rainfalls, along with flushing the town system, is helping to reduce contamination levels. The town will continue sampling until the levels of 1,4-Dioxane are not detected.
Pittsboro expects to release results of its sampling through July 9 tomorrow.
Also, the Environmental Management Commission is scheduled to discuss 1,4-Dioxane at its meeting tomorrow, which begins at 9 a.m.