Town, state studying chemical contaminants in river

Posted 6/14/19

PITTSBORO — The Haw River, which flows through Pittsboro, is “one of the most impacted” waterways in terms of unregulated chemicals in the Cape Fear Basin.

That’s according to Detlef …

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Town, state studying chemical contaminants in river

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PITTSBORO — The Haw River, which flows through Pittsboro, is “one of the most impacted” waterways in terms of unregulated chemicals in the Cape Fear Basin.

That’s according to Detlef Knappe, who’s been conducting research on water treatment processes for more than 25 years.

Knappe, the S. James Ellen Distinguished Professor of Civil, Construction and Environmental Engineering at N.C. State, was also a member of the team of scientists who discovered GenX in Wilmington’s drinking water. He began researching the Haw River in 2013, a study in which he discovered 1,4 Dioxane in the river, and subsequent years began studying PFAS in the water.

1,4 Dioxane is a solvent used in the manufacturing of other chemicals as a laboratory reagent and forms as a byproduct in some plastic production. PFAS are per- and polyfluoroalykl substances, a group of chemicals used to make coatings and products that resist heat, oil, stains, grease and water, and are common in firefighting foam. These chemicals are considered “unregulated contaminants,” meaning they are contaminants that are suspected to be present in drinking water and do not have health-based standards set under the Safe Drinking Water Act, according to the EPA. Unfortunately, for the most part, the chemicals can’t be eliminated through conventional water treatment methods.

An Environmental Protection Agency document summarizing the effects of 1,4 Dioxane described it as a likely human carcinogen. The EPA advises that .35 parts per billion creates a one in a million cancer risk in a lifetime. EPA considers 35 parts per billion, which would be 100 people in a million over a lifetime, as acceptable limits.

“For a town the size of Pittsboro, that would be like one in 10,000 in 70 years,” Knappe said. “It is statistically almost impossible to detect in a town like Pittsboro [because of its size].”

But Knappe noted that when he first started testing in Pittsboro, he initially saw levels as high as 80 parts per billion. In order to verify, he conducted a more significant study by sampling daily for several months. That study showed a range of 1,4 Dioxane in the water from nine parts per billion with a peak of 40 parts per billion, which is just above the cusp of what the EPA would deem advisable as safe for consumption.

PFAS can have adverse effects on human immune system and have been linked to thyroid, reproductive, kidney, liver and developmental disorders; some PFAS, but not all, are linked to cancer. The EPA only has a health advisory level for two PFAS — PFOA and PFOS — which it notes that the sum of the two should not be above 70 parts per trillion, a level, Knappe notes, that indicates Pittsboro is “often on that edge.”

“Pittsboro [through its water treatment plant] started using powder activated carbon to remove PFOA and PFOS [to the EPA’s guidelines] so it’s meeting its goal [for those],” Knappe said. “A lot of others, called shorter chain PFAS because they have fewer carbon atoms, have no guidelines.”

The Pittsboro Board of Commissioners has been discussing unregulated chemicals affecting its drinking water for several years, most recently contracting with CDM Smith, an engineering and construction company with an office in Raleigh, which provides solutions for water and environment, transportation, energy and facilities for municipalities and private clients, to study the town’s water supply and treatment plant expansion.

In discussing potential treatment options with the board at a meeting last month, the company noted that because of the combination and concentration of chemicals in the water, Pittsboro would likely need to consider a combination of techniques to remove the chemicals.

CDM Smith engineers provided four different advanced treatment options during the meeting for removal of the targeted chemicals, noting that none of the options were necessarily perfect because technology involved inthe removal of those particular chemicals for public utilities was still in the early stages of development. Each of the options also carries different capital costs to initialize. In addition, the company was unable to provide any operating costs because it were unsure how long the supplies required for each option to remove the chemicals will last considering the levels of chemicals in the Haw River and how much disposal costs for would be.

CDM Smith noted that a reverse osmosis treatment option would yield the best results, but was also the most expensive — with start-up costs of between $11-23 million alone. Another consideration for reverse osmosis is the after the chemicals are removed from the drinking water, they are returned back to the river. The “combination” treatment systems can cost between $8-21 million. However, other mediums used in the process, such as carbon, would also have to be disposed of either in a landfill or burned.

“I could argue it’s defensible what Pittsboro is considering [putting the chemicals back into the Haw River after the treatment of drinking water],” Knappe said. “You take the water out, clean it, then goes back into the Haw River from the wastewater plant. So they are simply bypassing people in the community. One way or another it’s still going into the system.”

Knappe noted his concern would be at the point of discharge and how well the concentrate would be mixed with the water.

“Is there any harmful impact on the aquatic life?” he asked. “That would be the greatest concern.”

Safe, Knappe said, “is in the eye of the beholder. Some may accept the risk while others may so ‘no, I don’t think this is acceptable.’ In the end, it’s an avoidable risk. These things shouldn’t be in the water.”

Knappe also said that it “shouldn’t be Pittsboro’s water plant to take care of” the chemicals in the water; rather, it “should be at the place where it’s generated,” a point made by members of Pittsboro’s town board last month. The town does not have any legal right to demand change from its neighbors upstream, but Knappe is hopeful that a move recently by the N.C. Dept. of Environmental Quality may signal a change.

On April 30, DEQ sent letters to 25 communities along the Cape Fear Watershed, which extends more than 200 miles from Reidsville to the Atlantic, requiring them to monitor PFAS and 1,4 Dioxane in their influent, the wastewater that comes into the plant. The towns chosen are those that contain pre-treatment facilities in their systems. Pre-treatment facilities are those built by certain industries to pre-treat wastewater before entering the town’s wastewater treatment facilities. Though owned and operated by the companies, the towns with such facilities are considered pre-treatment communities.

According to Sarah Young of DEQ’s Division of Water Resources, the department is initially targeting municipalities with pre-treatment facilities first because there is more industry discharging into those systems than industry discharging into systems without pre-treatment facilities. Each of the municipalities are also being asked to try to ascertain which industries may be discharging the chemicals as a result of their production processes. Young notes that DEQ is already drafting a letter that will be sent to those industries.

“I am cautiously optimistic,” Knappe said. “I feel the state will finally do what it needs to do. [I think] DEQ’s goal is to understand the impacts of wastewater on the entire Cape Fear Watershed and the state can cast a wider net.”

The towns include municipalities both upstream and downstream from Pittsboro and on other tributaries within the Cape Fear Watershed. Greensboro, Reidsville and Burlington, towns often noted by Pittsboro’s Board of Commissioners as significant contributors to the chemicals in the Haw, will be required to monitor 1,4 Dioxane and PFAS in their facilities. Those towns, according to a story published North Carolina Health News, have previously surveyed wastewater lines to determine sources of contaminants. Reidsville identified two potential manufacturers — Unifi and DyStar — and Greensboro identified one, although it refused to disclose the company’s name.

Siler City has also been asked to monitor its influent because it has two pre-treatment facilities — Brookwood Farms and Mountaire Farms — on its system. Since both those pre-treatment facilities are for food production, it is unlikely that they would produce those compounds, but others in the system may. According to Siler City’s Public Works Director Chris McCorquodale, Siler City will be conducting the testing as required by DEQ, noting that the town had previously conducted testing for 1,4 Dioxane in its influent several years ago, but the tests came out “blank” for that contaminant.

“The Town of Siler City understands the importance of reducing chemicals in our waters,” McCorquodale said. “These extra tests to make sure our waters are safe and clear is just one of the many things we are happy to do to make sure that we keep the environment as healthy as possible.”

Casey Mann can be reached at


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