State environmental officials are mulling a request from Wilmington’s predominate drinking water supplier to add another chemical compound to the list of PFAS the state is studying to understand potential health effects in people.
Cape Fear Public Utility Authority Executive Director Kenneth Waldroup met with members of the N.C. Secretaries’ Science Advisory Board Wednesday to talk about the challenge of removing perfluoropropionic acid, or PFPrA, from the utility’s raw drinking water source. The board advises the Department of Environmental Quality and the state Department of Health and Human Services in identifying contaminants of concern and determining which contaminants should be studied for public health risks.
More than one month has passed since the utility sent a letter to the board’s chair and DEQ, asking that PFPrA get added to the state’s priority per- and polyfluoroalkyl substances, or PFAS, list.
PFPrA is an ultra-short-chain PFAS. Ultra-short-chain chemical compounds are the smallest and hardest to remove during drinking water treatment.
In the year since the utility began operating its multi-million-dollar granular activated carbon system built specifically to remove PFAS from its raw water source, the Cape Fear River, smaller compounds, including perfluoro-2-methoxyacetic acid, or PFMOAA, have broken through the water treatment plant’s filtration, Waldroup said.
“We elected in an abundance of caution to increase our filter exchange,” he said.
Replacing filters more frequently ups the plant’s operating costs to an estimated $1 million annually.
The cost to replace one filter ranges between $600,000 to $700,000, Waldroup said.
CFPUA set a goal to prevent no more than 10 parts-per-trillion of PFMOAA from getting into treated drinking water going to 200,000 customers.
There are no federal or state limits on ultra-short-chain PFAS, so the utility chose the target of no more than 10 PPT to comply with proposed federal limits on six PFAS.
PFMOAA is not one of the compounds the U.S. Environmental Protection Agency proposes to regulate.
The agency is expected to finalize limits on a combination of four chemical compounds: GenX, perfluoronanoic acid, or PFNA, perfluorohexane sulfonic acid, or PFHxS, and perfluorobutane sulfonic acid, or PFBS; and set maximum contaminant levels, or MCLs, of 4 PPT each on perfluooctanoic acid, or PFOA, and perflurooctane sulfonic acid, or PFOS, two of the most widely studied PFAS.
PFMOAA is, however, on the state’s priority study list of PFAS.
During an online meeting Wednesday, Waldroup told members of the advisory board that PFPrA is breaking through the filtration system at “similar and even higher levels” than PFMOAA. The utility has set the same treatment target of no more than 10 PPT for PFPrA.
PFMOAA and PFPrA are among a number of chemical compounds specific to Chemours Fayetteville Works facility, which is more than 70 miles upstream of Wilmington.
The DuPont spinoff for decades discharged PFAS, including GenX, into the Cape Fear River, the air, and the ground.
Under a 2019 Consent Order between Chemours, DEQ and Cape Fear River Watch, the company has had to install technology, including a thermal oxidizer and underground barrier wall, to drastically reduce the amount of PFAS it discharges into the air and river.
A little more than a year ago, DEQ issued Chemours a discharge permit that ultimately limits the amount of PFMOAA that may be released from the plant to less than 20 parts-per-trillion, or PPT.
Waldroup told the board the utility is seeking state guidance in determining maximum limits for ultra-short-chain PFAS.
Utility officials are investigating the potential of new treatments that, when paired with the CAG, may help bolster PFAS removal.
Human health effects of PFMOAA and PFPrA are unknown.
A pilot study of the National Resource Defense Council across 16 states found PFPrA in 24 out of 30 samples. Half of the samples contained higher concentrations of PFPrA than any other PFAS detected those samples.
Amy Delinsky, an environmental chemist with DEQ, explained that PFPrA is used to replace now-banned chlorofluorocarbons, or CFCs, which were primarily used as refrigerants.
“The amount of PFPrA is actually expected to increase with time as a result of the use of these replacement refrigerants,” Delinsky said. “PFPrA also can be found in the environment as the result of the breakdown of longer-chain PFAS. Certain manufacturing facilities can produce PFPrA associated with some of the process that’s happening at the facility, whether it’s direct manufacturing or as a byproduct.”
PFPrA is found throughout the world.
Chemours “does appear to be the main source of PFPrA in the southeast part of the state,” Delinksy said.
The state Division of Water Resources has multiple testing stations through the state, including one at Lock and Dam Three in the Cape Fear River near Chemours.
PFPrA was detected between 1,000 and 1,500 PPT from water samples taken at that site in May and June of 2022, Delinksy said.
Seven out of 286 public water supply wells DWR sampled this year contained PFPrA above 20 PPT.
Those systems are in five counties in the Cape Fear, White Oak, and Tar-Pamlico river basins. Those counties include: Carteret, Cumberland, Franklin, New Hanover, and Pender.
Delinksy said the state will continue to gather additional data and work with the advisory board to develop specific questions related to CFPUA’s request to discuss at the board’s Dec. 6 meeting.