RALEIGH, N.C. (WITN) – 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 DEQ says the treatment system is part of the larger barrier wall remediation project to substantially lessen PFAS from entering the Cape Fear River and impacting downstream communities.
WITN is told that the permit is a National Pollutant Discharge Elimination System permit for a granular activated carbon (GAC) filtration treatment system. The DEQ says the permit limits for the three indicator compounds have been significantly reduced beyond the 99% removal required in the consent order.
The DEQ says the contaminated groundwater currently 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 department says that during the initial optimization period of the system, the permit limits will be: 120 ng/L (ppt) for GenX, 100 ng/L (ppt) for PMPA, and 320 ng/L (ppt) for PFMOAA. 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. These limits represent an estimated removal efficiency of greater than 99.9%.
According to the DEQ, the plan is the largest of its kind to address PFAS. 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. The groundwater will be pumped and treated to remove 99.9% of PFAS compounds before being released into the river.
The NPDES permit includes weekly monitoring upstream and downstream of the treatment system during barrier wall construction to track progress and efficiency. After a year, an evaluation can take place to add new data and tighten limits further if needed. The DEQ also adds that the permit can be reopened to add limitations based on new toxicity data, an introduction of federal or state PFAS standards, or if another PFAS compound breaks through the treatment system more quickly than the three current indicator parameters.
The DEQ says it has also issued an approval letter for the design of the barrier wall, including conditions for more monitoring wells, the sampling of extraction wells, and management of contaminated groundwater during barrier wall construction.
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