Thursday, July 25, 2024

PFAS detected at offline CFPUA wells, none detected in aquifer-sourced finished water

Cape Fear Public Utility Authority's latest round of PFAS testing is in: PFAS detections are up at an offline storage well, but absent from finished water at the groundwater-sourced Richardson Water Treatment Plant. This plant serves northern New Hanover County customers.

Cape Fear Public Utility Authority latest round of PFAS testing is in, and PFAS detections are up at an offline storage well, but absent from finished water. (Port City Daily/Courtesy CFPUA)

NEW HANOVER COUNTY — Higher than expected amounts of per- and polyfluoroalkyl substances (PFAS) were detected at an offline CFPUA well near Bradley Creek in Wilmington late last month.

PFAS were detected at three other Cape Fear Public Utility (CFPUA) wells, but PFAS are not showing up in finished water treated by the Richardson Water Treatment Plant, according to a CFPUA release Monday.

Related: CFPUA’s raw water supply line to be rerouted under Highway 421 following Florence wash out

The wells that were tested get their source water from the PeeDee aquifer. Treated at the Richardson Water Treatment Plant, finished water is supplied to CFPUA customers in northern New Hanover County.

Levels of PFAS at CFPUA’s Aquifer Storage and Recovery (ASR) are still being detected at levels far greater than the other wells. In 2017, CFPUA briefly used the ASR to store water from the Sweeney Treatment Plant – water that was treated but still contained very high levels of GenX. After high GenX levels were detected in the ASR, CFPUA discontinued using it as a storage area, and subsequently pumped 50 million gallons of water back out of the aquifer.

PFAS levels in and around the ASR

Levels of combined PFAS at the ASR were detected at 2,263 ppt on March 27.

That’s higher than CFPUA’s previous round of results which showed PFAS at the offline ASR well at 1,982 ppt between Jan. 21 and 23 testing period. Monitoring wells — also currently offline — several hundred feet away were also tested, revealing PFAS but at far lower levels. For example, one well showed levels of 216 ppt total PFAS. Closer to Wrightsville Beach, PFAS were detected at 947 ppt and 621 ppt at two wells just south of Lumina Station.

Testing in late March at the three wells feeding the Richardson plant showed total PFAS levels at 36, 65, and 180 ppt. The well closest to the ASR had the highest levels, but according to CFPUA “not enough information is available to determine whether the PFAS found in the water from the three wells migrated from the ASR.” CFPUA noted that groundwater typically moves several meters per year, and the Richardson wells are 2 to 3 miles from the ASR.

According to CFPUA, Richardson Water Treatment plant utilizes “state-of-the-art” nanofiltration membrane technology. In 2017, GenX was not found in water treated at the plant.

Last week, the utility’s board approved a $46 million plan to upgrade its treatment system at the Sweeny Water Treatment Plant. Adding eight granular activated carbon (GAC) filters to the plant will improve PFAS treatment efficiency, according to the utility.

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