One sample of raw — or untreated — drinking water in Pittsboro contained levels of 1,4-Dioxane above the health advisory goal, and concentrations in treated water continue to rise, according to test results released late this afternoon by the town.
On Nov. 16, a sample of raw water contained 38.1 parts per billion of 1,4-Dioxane, a likely carcinogen. The EPA’s and the state’s health advisory goal is 35 ppb; that’s equivalent to a 1-in-10,000 excess cancer risk over a lifetime of exposure. That goal is not as protective as the surface water goal of 0.35 ppb, which represents a 1-in-1 million excess cancer risk.
Finished drinking water at the town’s treatment plant rose from 16.8 ppb to 21.3 ppb over just one day: Nov. 15-16. However, the town can instead use water in storage tanks, which have much lower concentrations, between 1 ppb to 4.6 ppb.
“Town staff remains concerned by the increase in 1,4-Dioxane levels seen in raw water samples,” Town Manager Chris Kennedy said in a press release, “and will continue to exert our energies toward manipulating our water operations in an effort to reduce the concentration levels in our water distribution lines.
The source of the 1,4-Dioxane is Greensboro’s TZ Osborne wastewater treatment plant, which on Nov. 3 illegally discharged high amounts of the compound — 767 ppb — into a tributary of the Haw River. The river serves as Pittsboro’s drinking water supply.
The ultimate source of the 1,4-Dioxane is likely an industrial customer of Greensboro’s. The city has not publicly announced the responsible industry.
The EPA has yet to regulate 1,4-Dioxane in drinking water.
On Nov. 8 and 9, town officials found low levels of 1,4-Dioxane in the water supply and believed the slug of the compound had passed the raw water intake during a time of low demand.
But dry weather has slowed the water flow in the Haw, and several residents said at the time that levels in the town’s drinking water supply were low only because the slug had not arrived yet.
That turned out to be true.
When the most recent spill occurred, Greensboro had a goal of just 45 ppb in its discharge, according to a Special Order by Consent between the NC Department of Environmental Quality and the city. That order was the result of a major 1,4-Dioxane spill in 2019; a subsequent spill last year also violated the terms of the order.
The Haw River Assembly and Fayetteville Public Works, whose water supply is also degraded by these releases, legally challenged the order and asked for stronger environmental protections.
Today the Environmental Management Commission approved a settlement agreement that reduces the goal to 35 ppb in the first year, and 23 ppb by the third year of the order.
Greensboro must also sample its industrial sources, publicly post its sampling data and information about its investigation of pollution sources. It further requires Greensboro to sample downstream at Pittsboro’s drinking water intake on the Haw River and in Jordan Lake.
“The agreement puts Greensboro on the path to controlling its 1,4-dioxane pollution and protecting downstream communities, but it isn’t the last word,” said Geoff Gisler, senior attorney at the Southern Environmental Law Center, which represented the Haw River Assembly and the City of Fayetteville. “We’ll monitor the sampling and watershed investigations secured as part of this settlement and ensure polluters are held accountable. We encourage DEQ to go beyond those investigations and act on Greensboro’s pending permit application to impose strict limits on 1,4-dioxane pollution to protect communities downstream over the long-term.”
“Without these legal challenges brought by Haw River Assembly and City of Fayetteville, the original order would have allowed Greensboro to continue polluting the Haw River with higher levels of 1,4-dioxane, and with much lower penalties for extraordinarily high discharges,” said Emily Sutton, the Haw Riverkeeper. “The monitoring required under this agreement will identify the industries responsible for these toxic discharges in Greensboro and put the responsibility of safe and clean water on polluters, instead of the downstream users.”