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By Greg Barnes
The North Carolina Environmental Management Commission wants additional investigation of a large discharge of the likely carcinogen 1,4 dioxane that was detected on June 30 at a Greensboro wastewater treatment plant.
The commission voted Tuesday to direct the state Department of Environmental Quality’s Division of Water Resources to investigate the discharge, which resulted in elevated levels of the contaminant reaching downstream Pittsboro’s drinking water supply.
The Division of Water Resources was directed to report its finding and recommendations to the commission.
The decision followed a closed-door meeting in which the commission said it was going to discuss a petition filed on behalf of the Haw River Assembly and the city of Fayetteville that seeks to overturn a special order by consent that the DEQ entered into with Greensboro earlier this year.
The Southern Environmental Law Center, which filed the challenge, says the order violates the federal Clean Water Act and North Carolina’s water quality laws. The SELC believes the amount of 1,4 dioxane that is permitted under the order to leave Greensboro’s T.Z. Osborne wastewater treatment plant is too high.
Among many other things, the order caps the amount of 1,4 dioxane, a solvent stabilizer and degreaser, that can leave the plant at 45 parts per billion the first year and 33 parts per billion the following year. The order also requires Greensboro to sample industries’ wastewater in an effort to detect the sources of the contamination.
“We believe that the discharge should be investigated thoroughly and will continue to monitor the process,” said Jean Zhuang, a SELC attorney. “These 1,4 dioxane spikes should not be happening.”
Elevated levels reach Pittsboro
On June 30, Greensboro officials said they detected a release of 1,4 dioxane at the T.Z. Osborne treatment plant that measured as much as 687 parts per billion, which is nearly 20 times higher than the amount the U.S. Environmental Protection Agency considers safe for drinking water.
The contaminant left the plant at South Buffalo Creek and flowed into the Haw River, where the town of Pittsboro draws its drinking water.
The town issued a news release Monday that showed 93.6 parts per billion of 1,4 dioxane entered the town’s raw water – water before treatment – at one testing site on July 6. A sample in treated drinking water measured 57.6 parts per billion at the same testing location.
The EPA does not regulate 1,4 dioxane but has set a health advisory of 35 parts per billion. At that level of consumption over a lifetime, the EPA estimates that one in 10,000 people would get cancer. North Carolina’s drinking water standard for surface waters is 0.35 parts per billion. At that level, one in 1 million would be expected to get cancer.
Greensboro says Shamrock not to blame
Two years ago, Greensboro detected an even larger release of 1,4 dioxane leaving its sewer treatment plant. After that release, which prompted the DEQ’s consent order, the city identified Shamrock Environmental Corp. as the responsible party.
But this time, Elijah Williams, the city’s water reclamation manager, reiterated in an email Tuesday that he doesn’t think Shamrock is responsible for the latest discharge. The company provides environmental decontamination services to other industries.
Williams says Shamrock is probably not to blame even though a “flume grab” of the company’s sewer waste showed a concentration of 1,4 dioxane at 466 parts per billion on July 7, according to a document Williams shared with NC Health News and has submitted to the DEQ.
Williams said the dilution factor would have substantially reduced the level of 1,4 dioxane before it reached Greensboro’s treatment plant. For Shamrock to have been responsible, he said, it would have had to release 1,4 dioxane measuring in the thousands of parts per billion.
A news release from Pittsboro Town Manager Chris Kennedy said his staff believes test samples of the town’s drinking water since the spill “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 coming from Greensboro on or immediately before July 6.”
According to the news release, the town is turning over the water in its storage tanks more often in an effort to rid the system of the contaminant. It also flushed the water out of its Chatham Forest tanks.
Kennedy wrote that he is encouraged that the levels now being seen in test samples, while still above detection levels, have dropped significantly.
“The town remains confident that our water is safe for consumption and use in both residential and commercial applications,” he wrote.
Pittsboro is the only municipality to draw its drinking water from the Haw River. The Haw flows into the lower end of Jordan Lake and then into the Cape Fear River, where nearly 1 million people get their drinking water.
When a similar spill was detected in Greensboro two years ago, the city failed to notify downstream water users, which detected elevated levels of the contaminant. Under DEQ regulations, the city was required to notify cities downstream.
After the latest spill was detected, Greensboro said it quickly notified downstream water users. Fayetteville and Wilmington had not reported elevated levels of 1,4 dioxane but continue to test for it.
The contaminant has historically been used as a solvent and solvent stabilizer. It can be found in paint strippers, dyes, greases, antifreeze and de-icers. It can also be found in some consumer products, including deodorant, shampoos and cosmetics.
Because 1,4 dioxane is not federally regulated, industries are not required to report a spill. Greensboro and other cities hold state pre-treatment permits that require them to notify the DEQ when a discharge is detected.