RALEIGH – The North Carolina Department of Environmental Quality has issued the 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 the larger barrier wall remediation project to substantially reduce PFAS entering the Cape Fear River and impacting downstream communities.
After a comprehensive review and public process, DEQ’s Division of Water Resources has issued a National Pollutant Discharge Elimination System (NPDES) permit for a granular activated carbon (GAC) filtration treatment system. 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.
During an initial period to optimize the performance 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%.
The NPDES permit includes weekly monitoring upstream and downstream of the treatment system during barrier wall construction to track progress and efficiency. It also allows for an evaluation after one year to incorporate new data and further tighten limits if appropriate. The permit can also be reopened to add limitations based on new toxicity data, 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.
The massive remediation project 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 ultimately remove an estimated 99.9% of PFAS compounds before being released into the river.
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.
In addition, DEQ issued an approval letter for the design of the barrier wall. The approval includes conditions for additional monitoring wells, sampling of extraction wells, and management of contaminated groundwater during barrier wall construction.
DEQ is also 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 permit, hearing officer’s report, and approval letter are available online.