Post-rainfall spikes of GenX shift regulators' focus to soil

It's the fourth such leak of the chemical known as GenX at Chemours' Fayetteville Works plant since Dec. 9. But officials with the state Department of Environmental Quality say they don't believe the spills, all of which contained only minute amounts of the potentially harmful compound, are responsible for spikes in GenX they've seen in river water near the plant.

Timeline: Tracking GenX contamination in NC

"What we are looking at now is why we are seeing spikes in our sampling following rain events," DEQ spokeswoman Bridget Munger said.

As part of a full site assessment of the plant, Munger said regulators are waiting for the results of soil sampling that might explain why contamination increases after heavy rain. Those results may be back from the lab as soon as next week.

Used in the creation of Teflon and other industrial products, the health effects of GenX aren't well understood. But it's closely linked with a family of so-called perfluorinated compounds known to cause cancer, and state health officials have set a preliminary safety threshold for GenX in drinking water of 140 parts per trillion.

The plant no longer releases wastewater from the processes that produce GenX as a byproduct, per orders from the state. Munger said the outfall pipe that used to connect to those processes has been completely capped off.

That means there's another cause of spikes like the one on Dec. 11, when samples in untreated water from the Cape Fear River adjacent to the Fayetteville Works plant showed GenX at 2,300 parts per trillion. One week later, levels dropped back down below the safety threshold.

"It's very frustrating, but I want to emphasize that spike is not coming from the manufacturing process wastewater. That is stopped," DEQ Assistant Secretary for Environment Sheila Holman said in an interview with WRAL News Friday. "It is being put into tankers and shipped offsite for disposal in other ways."

Holman said one theory for the spikes could be rainwater that mixes with contaminated soil before it reaches the river. Groundwater contamination near the outfall into the river could be also be the culprit.

"We're requiring the company to look at both of those possible mechanisms and take action to eliminate these spikes," Holman said.

In addition to soil sampling, Munger said, regulators have installed additional groundwater monitoring at the plant, are analyzing air emissions from the facility's stacks and continue to perform regular testing of the nearby river water.

"We're looking at all possibilities," Munger said.