The North Carolina Department of Environmental Quality has issued a discharge permit for a treatment system to remove PFAS compounds from contaminated groundwater on the Chemours Fayetteville Works site.
The treatment system is part of a larger barrier wall remediation project to substantially reduce PFAS entering the Cape Fear River and polluting the water of communities downstream, the agency said in a release.
DEQ also issued an approval letter for the design of the proposed underground barrier wall. The approval includes conditions for additional monitoring wells, sampling of extraction wells, and management of contaminated groundwater during the wall’s construction, the release states.
Lisa Randall, the regional communications manager for Chemours, said the company is still reviewing the information from DEQ.
“That’s about all we have to say at this point,” she said.
Dana Sergeant, executive director of Cape Fear River Watch, said the permit to make Chemours reduce PFAS in the Cape Fear River basin needed to happen. It was part of the 2019 consent order, she said.
In 2019 a consent order was entered between DEQ, Chemours and Cape Fear River Watch to clean up decades of per- and polyfluoroalkyl contamination — also known as PFAS — that have been emitted from the plant into the air and the Cape Fear River.
Based on the requirements of the consent order, Chemours had requested a new National Pollutant Discharge Elimination System (NPDES) permit for the discharge of treated groundwater, treated stormwater, and treated surface water from seeps located on its property.
According to the DEQ release, after a review and public process, DEQ’s Division of Water Resources has issued a NPDES permit for a granular activated carbon (GAC) filtration treatment system.
The release also states that after consideration of the public comments and further review of data and information contained in the permit record, the permit limits for the three indicator compounds have been significantly reduced beyond the 99% removal required in the consent order.
“The original draft of 99 percent reduction was not enough with the amount of PFAS getting into the river,” Sergeant said.
Sergeant said the permit is stricter than an initial draft proposed by Chemours. Because of the amount of PFAS getting into the water supply, even 99% is too lax.
“That’s something we’ve been pressing DEQ for more than a year,’’ she said.
Sergeant said the consent order requires the company to use existing technology that works, and the company has to maintain that technology to the utmost.
“They can’t be shoddy or lazy,’’ she said. “They have to maintain it at 100 percent level. They (Chemours) are going to have to do a good job.”
“This is a big win. DEQ is listening to the community,” Sergeant said.
Chemours will be given an initial period to optimize the performance of the system, the release states. During that phase, the permit limits will be: 120 ng/L (ppt) for GenX, 100 ng/L (ppt) for PMPA and 320 ng/L (ppt) for PFMOAA.
However, after the 180-day optimization period, the limits will drop to less than 10 ppt for GenX, 10 ppt for PMPA, and less than 20 ppt for PFMOAA, the release states.
These limits are estimated to remove more than 99.9% of the chemical compounds, the release states.
The NPDES permit also requires weekly monitoring upstream and downstream of the treatment system while Chemours builds the barrier wall. It also allows for an evaluation after one year to incorporate new data and further tighten limits if needed, the release states.
The permit also can be reopened to add limitations based on new toxicity data, the introduction of federal or state PFAS standards, and if another PFAS compound breaks through the treatment system more quickly than the three current indicator parameters, according to the release.
The remediation project is the largest of its kind to address PFAS, DEQ says in the release. The system involves a mile-long underground barrier wall, more than 70 extraction wells, and the GAC treatment system to intercept and treat groundwater contaminated by years of pollution at the facility, according to the release.
The groundwater will be pumped and treated to ultimately remove an estimated 99.9% of PFAS compounds before being released into the river, the release states.
Currently, the contaminated groundwater flows untreated directly into the Cape Fear River. This project is designed to reduce the largest ongoing source of PFAS contaminating the river and reaching downstream water intakes and must be operational by March 15, 2023, the release states.
In a letter to Chemours plant manager Dawn Hughes, DEQ outlined several conditions to its approval of the barrier wall design.
They include:
DEQ is finalizing the 401 Water Quality Certification to minimize and address impacts during the construction of the barrier wall in conjunction with the 404 Permit from the U.S. Army Corps of Engineers, the release states.
