Pittsboro water samples suggest additional 1,4-dioxane contamination from unknown source in Greensboro
PITTSBORO – A second round of Pittsboro water tests released Monday suggests another 1,4-dioxane ‘slug’ was illegally dumped into the Haw River a week after Greensboro officials announced a release substantial point from a still unknown source.
On July 1, the City of Greensboro and the North Carolina Department of Environmental Quality reported a release of 1,4-dioxane into South Buffalo Creek, a tributary of the Haw River, in the effluent of TZ Osborne Wastewater Treatment Plant in Greensboro. The chemical is a suspected carcinogen derived from industrial runoff.
Preliminary samples at Greensboro have indicated levels between 543 parts per billion and 687 parts per billion of 1,4-dioxane in the water there. The United States Environmental Protection Agency does not recommend more than 35 ppb in drinking water.
After learning of the pollution, Pittsboro staff began testing the city’s water supply, Pittsboro water plant manager Adam Pickett told News + Record and took samples. daily since. A first set of results, which was processed at Meritech Labs in Reidsville, came back last Wednesday.
In the immediate wake of the Greensboro contamination, the 1,4-dioxane levels at the Pittsboro raw water intake were undetectable. Two days later, a raw water sample comprised 76.5 ppb, and subsequent samples showed 38.2 ppb and 43.7 ppb over the following days, all exceeding EPA guidelines. The treated water in the Pittsboro water tanks contained much lower concentrations of 1,4-dioxane, none exceeding 5.56 ppb.
On Monday, however, city officials announced a troubling finding: There appears to have been at least a second 1,4-dioxane dump from Greensboro, they say, although none have officially been released. reported. A new batch of water samples showed a spike in 1,4-dioxane levels at the Pittsboro water intake a week after the initial fear.
Raw water samples from July 6 showed 1,4-dioxane ranging from 26.5 ppb to 93.6 ppb, a higher ceiling than previously detected. The concentration of the chemical in treated drinking water was also high. At the Chatham Forest water reservoir, levels reached 66.8 ppb. The city’s 1.0 M reservoir posted 21.7 ppb. The treated water from the Horton Reservoir was much lower, only 1.71 ppb.
“City staff believe these numbers indicate a delayed or secondary influx of 1,4-dioxane reaching the Pittsboro raw water intake with what appears to be an additional slug of contamination from Greensboro on or immediately before the 6th. July 2021 … “CEO Chris Kennedy said in a statement.
After seeing the test results, city staff rinsed the Chatham Forest reservoir and filled it with what they “expect to be less contaminated finished water given the decrease in contamination. of raw water from July 6 (93.6 ppb) to July 7 (26.5 ppb), ”the press release said. “From a strategic point of view, the City continually returns the water stored in our water tanks more frequently than usual to continually refresh the water with improved and better quality finished water so that contaminated water. 1,4-dioxane is leaving our public supply as quickly as possible.
At press time on Tuesday, two weeks after the initial 1,4-dioxane contamination, the original source of the chemical remained unknown. Greensboro is required to limit releases of 1,4-dioxane under a special consent order between the city and the NCDEQ signed in February. The SOC states that no more than 45 parts per billion 1,4-dioxane can be released per day.
The deal was triggered in 2019 after the discovery that Shamrock Environmental – an environmental and industrial waste management services company – was dumping 705 parts per billion to 1,210 parts per billion of 1,4-dioxane at the TZ Osborne plant. . Shamrock’s site in Greensboro is a tanker cleaning facility that also manages wastewater and recycles drilling mud.
Water samples from the Shamrock effluent showed 98.8 ppb 1,4-dioxane on July 6 and 7 and 466 ppb on July 7 in a “channel gripper” – water that did not had not been mixed with other sources at the sewage treatment plant. But Greensboro spokesman Elijah Williams, in an interview with NC Policy Watch, said Shamrock was not the source of contamination appearing in Pittsboro water.
“Taking into account the dilution factors,” the report said, “Shamrock’s levels should have been much higher for him to be responsible for this spill.”
Other potential sources of the contaminant had not been released at the time of going to press. Greensboro’s only official public notice is the original July 1 announcement on the city’s website.
“City staff have notified and are coordinating with the North Carolina Department of Environmental Quality (NCDEQ) and downstream utilities and are actively investigating possible sources of the substance,” it read. .
The notice states that “this discharge does not affect the quality of Greensboro’s drinking water”.
“So that’s what Greensboro is working on,” said Pickett, the Pittsboro water superintendent, “trying to figure out where that source is coming from all of a sudden. And we’re working with Greensboro as well, so I’m working on it. hope we can sort this out pretty quickly. ”
It is not clear whether the City of Greensboro or private companies identified as having dumped 1,4-dioxane in the Haw will be required by the NCDEQ to pay financial penalties for the contamination.
Despite the second spike in 1,4-dioxane levels and the uncertainty of the location of the chemical’s source, Pittsboro staff maintain the city’s drinking water is safe to drink.
“Although the numbers are above undetectable based on the latest sample results,” Kennedy said in the statement, “we are encouraged by the July 6-7 drop in our raw water sample and the trends shown in Greensboro water uptake … trend toward non-detection level.
A third set of water sample results were due to be released after press time. For the latest news on Pittsboro’s water quality, check out this story for updates.
Journalist D. Lars Dolder can be reached at [email protected] and on Twitter @dldolder.