The city of Cary's wastewater treatment plant, where officials are monitoring raw sewage for the coronavirus: Photo credit: City of Cary
The city of Cary's wastewater treatment plant, where officials are monitoring raw sewage for the coronavirus: Photo credit: City of Cary

By Greg Barnes

Another release of the likely carcinogen 1,4 dioxane was detected at a Greensboro wastewater treatment plant. Unlike a similar incident in 2019, this time the city quickly notified water utilities for Pittsboro, Fayetteville, Wilmington, Cary and other downstream municipalities.

On June 30, two samples taken from effluent at Greensboro’s T.Z. Osborne wastewater treatment plant contained levels of 1,4 dioxane that averaged 615 parts per billion, nearly 18 times higher than the U.S. Environmental Protection Agency’s health advisory of 35 parts per billion.

As of Wednesday, a Greensboro official said the city was still awaiting additional sampling results to determine whether the contamination had stopped. It was also trying to identify the industry responsible for the discharge.

According to the Centers for Disease Control and Prevention, “exposure to very high levels of 1,4-dioxane can result in liver and kidney damage and death.”

Many municipalities downstream of Greensboro have posted information about the release on their websites to alert water customers of the potential danger. Officials in Fayetteville and Wilmington, among the farthest cities from Greensboro in the Cape Fear River basin, said they had not detected elevated levels of 1,4 dioxane. They said they will continue to monitor water quality daily for the contaminant until the risk is known to have passed.

Pittsboro, the closest water user to Greensboro, detected elevated levels in its drinking water, but Adam Pickett, the town’s public utilities director, said the levels were nowhere close to reaching the EPA’s health advisory level. He said the highest level detected was about 5.5 parts per billion. 

Pickett said the town conducted a “code red alert” on the Chatham County emergency management messaging system to inform residents. The utility continues to test its drinking water daily.

Greensboro’s treatment plant discharges into South Buffalo Creek, which empties into the Haw River. The Haw flows into the southern end of Jordan Lake, which empties into the Cape Fear River.

In other words, the discharge of 1,4 dioxane in Greensboro had the potential to temporarily foul the drinking water for nearly 1 million people.

Greensboro’s past failure to notify

Greensboro’s decision to quickly notify downstream water users was a far cry from what happened two years ago, when a larger discharge of 1,4 dioxane was discovered at the treatment plant.

After that release, detected in August 2019, Greensboro failed to notify any downstream water users within 24 hours, a violation of state Department of Environmental Quality regulations. In fact, the DEQ and cities downstream of Greensboro never learned about the release until more than a month later, after the contaminant had dissipated and flowed out to sea.

During that release, 1,4 dioxane was detected in Pittsboro’s drinking water at 107 parts per billion, nearly three times the level the EPA considers safe for human consumption. Pittsboro is the only municipality to draw its drinking water from the Haw River.

Elevated levels of 1,4 dioxane were also detected back then in Fayetteville and Wilmington, which draw their drinking water from the Cape Fear River. Although the levels were far below the EPA’s health advisory, they were well above the DEQ’s 0.35 parts per billion standard for surface waters used for drinking.

1,4 dioxane is a synthetic that has historically been used as a solvent stabilizer. It can be found as a by-product in many goods, including paint strippers, dyes, greases, antifreeze and aircraft deicing fluids, and in some consumer products, including deodorants, shampoos and cosmetics. The chemical is also used by industries that recycle plastic bottles.

Despite its toxicity, 1,4 dioxane remains unregulated. There is no maximum contaminant level for the substance — the EPA’s health advisory of 35 parts per billion is the only federal standard, and it has no teeth. A person who consumes that amount over a lifetime stands a 1 in 10,000 chance of getting cancer.

Greensboro gets punished, fined

Greensboro’s failure to notify downstream water users and to abide by the conditions of its wastewater discharge permit led the DEQ to issue the city a notice of violation and a $5,000 fine in 2019. Reidsville received an almost identical notice for an even larger spill detected in October of that year.

The DEQ didn’t stop there. In February of this year, the department entered a consent agreement with Greensboro that, among many other things, caps the amount of 1,4 dioxane that can legally leave the treatment plant during any sampling period at 45 parts per billion the first year and 33 parts per billion the year after that.

The agreement also spells out the amount of fines that can be issued to the city for future violations, maintains the 24-hour notification rule to downstream drinking water users, and requires Greensboro to provide a written report to the DEQ stating the cause, effects and duration of the discharge within five days of detection.

In the latest discharge, the city provided the report three days after the 1,4 dioxane was detected at the treatment plant. The document shows that a sample taken at 7 a.m. on June 30 measured 1,4 dioxane at 543 parts per billion. A second sample that morning came in at 687 parts per billion. The average of the two samples is 615 parts per billion, the level Greensboro reported to downstream users.

Shortly after 2 p.m., the document shows, Greensboro officials began notifying the DEQ and downstream water users. About the same time, the city contacted Shamrock Environmental Corp., a decontamination service that was found to be responsible for the 2019 discharge. A Shamrock official said at the time that a company it accepted waste materials from failed to disclose that the waste contained 1,4 dioxane.

Another industry could be to blame

The document shows that a Greensboro official asked Shamrock to put a rush on the analysis of its last five daily sampling composites.

Elijah Williams, the city’s water reclamation manager, said he suspected that Shamrock might again have been responsible for the latest discharge. But on Wednesday, Williams said he now doesn’t think that’s the case.

“With their initial samples they had ran, it didn’t seem to be them, which means that this potentially is a different source than the source we’ve been dealing with, or an additional source,” Williams said. “So that’s what’s disheartening to me…I can’t say 100 percent but it’s looking like this is not coming from Shamrock.”

Now, Williams and his staff are scrambling to find out where the 1,4 dioxane may be coming from. 

Williams said the city began doing sewer trunk line inspections Wednesday morning. He explained that officials can inspect a trunk line — a main sewer pipe with many branches — from manholes in an effort to detect 1,4 dioxane. If the contaminant is found there, he said, the officials can zero in farther to lines coming from individual industries. 

Environmentalists file lawsuit

Greensboro has known about high levels of 1,4 dioxane entering its wastewater treatment plant at least since 2014, after the federal government required larger cities and towns to test for it. The following year, the city voluntarily began a source identification and reduction plan. 

According to the special order by consent, the city met with industry leaders to ask for their assistance in identifying polluters. Since 2016, the order says, the level of 1,4 dioxane detected at the treatment plant has been reduced by half.

Environmentalists, however, say the amount is still far too high. Documents NC Health News obtained from the DEQ in 2019 show that between December 2017 through September 2019, the levels of 1,4 dioxane detected at Greensboro’s treatment plant exceeded the EPA’s health advisory eight out of 20 months. The levels were even worse in Reidsville, where the health advisory was exceeded 20 out of 27 months. 

Environmentalists say the special order by consent doesn’t go nearly far enough. 

In April, the Southern Environmental Law Center filed a legal challenge to the order on behalf of the Haw River Assembly, arguing that the order violates the federal Clean Water Act and North Carolina’s water quality laws. 

The order could allow even more 1,4 dioxane into the Haw River because the cap on the amount Greensboro detects without having to report it is now routinely lower than the amount specified in the order, said Jean Zhuang, an attorney for the SELC.

“We’ve challenged the special order by consent because it does not require compliance with water quality standards and won’t protect downstream communities like Sanford, Fayetteville and those in Wilmington,” Zhuang said. “This latest discharge released by Greensboro really shows why the special order by consent is inadequate and the consequences of DEQ and Greensboro not taking the city’s discharges seriously.”

Among other objections, Zhuang called the penalties of up to $2,000 for violating the consent order a “slap on the wrist.” She noted that the caps on the 1,4 dioxane levels leaving the treatment plant that would trigger a violation of the order “are about 100 times higher than what the (state’s) water quality standard requires, which is 0.35 parts per billion.” 

The order says its primary goal is to ensure that 1,4 dioxane leaving the treatment plant will not reach the EPA’s health advisory of 35 parts per billion in downstream drinking water.

Zhuang said the SELC also objects to a provision in the order that requires Greensboro to only investigate industries identified as capable of releasing more than 100 parts per billion of 1,4 dioxane. 

“Based on what happened in 2019, at least one of these industries is a huge problem and we suspect that there could be others,” Zhuang said. “We just really don’t know because Greensboro hasn’t done that rigorous survey of its industries with a target of meeting water quality standards, and the SOC doesn’t require them to do that rigorous survey.,”

The special order by consent is set to expire on April 30, 2023.

Correction: This story initially incorrectly reported the June 30 1,4-dioxane readings were at 543 parts per trillion and later, at 687 parts per trillion. Those values are actually parts per billion, a higher amount.

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Greg Barnes

Greg Barnes retired in 2018 from The Fayetteville Observer, where he worked as senior reporter, editor, columnist and reporter for more than 30 years. Contact him at: gregbarnes401 at

3 replies on “Another release of a toxic substance causes alarm in the Cape Fear River basin”

  1. Perhaps it might balance the story a little if:
    – you add context to “likely carcinogen.”
    – ask DEQ where exactly the EPA came up with with the 35 ppb water quality standard
    – clarify that 0.35 ppb is the drinking water standard
    – ask DEQ how realistically attainable the 35 ppb 1,4 dioxane concentration really is

  2. “In the latest discharge, the city provided the report three days after the 1,4 dioxane was detected at the treatment plant. The document shows that a sample taken at 7 a.m. on June 30 measured 1,4 dioxane at 543 parts per trillion. A second sample that morning came in at 687 parts per trillion. The average of the two samples is 615 parts per billion, the level Greensboro reported to downstream users.”

    Check your math.

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