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Carbonic cleansing reopens North Rivanna water plant

The unhealthy “forever chemicals” that pushed a local water treatment plant out of service this summer appear to have been removed by a technology introduced to cure a prior controversy.

Officials with the Rivanna Water and Sewer Authority began treating all — and not just some — of the water at the North Rivanna treatment plant with granular activated carbon, according to Dave Tungate, the authority’s operations director.

“We were happy to see the results as proof of the technology that we use and the science that we subscribe to,” Tungate told The Daily Progress.

Tungate said the granular activated carbon appears to have scrubbed the plant’s finished water to the point that the latest tests show no detectable levels of PFAS, the concerning class of chemicals called “forever” because they don’t break down in human bodies or ecosystems.

It was a different story two months ago when tests of the finished water emerging in May from the North Rivanna plant found levels exceeding the Environmental Protection Agency’s voluntary targets. When the authority received those results in early July, one compound called PFOS was detected at 6.5 parts per trillion, and another called PFOA was detected at 25 parts per trillion. In other words, the North Rivanna plant was sending customers drinking water 63% above the EPA’s four-parts-per-trillion standard for PFOS and 625% of the standard for PFOA.

The EPA’s current standards are voluntary for this class of chemicals, but the standards appear on a fast-track to carry the force of law as the agency copes with emerging science that links PFAS exposure to a host of medical issues, including kidney cancer, abnormally high cholesterol, decreased antibody response, as well as infant and fetal growth problems. Several states have enacted standards far higher than the EPA’s four parts per billion target.

Tungate concedes that mother nature may have played a role in reducing the recent concentrations due rainfall and other factors.

“The raw water changes quality on a regular basis,” said Tungate.

In the most recent tests at an independent lab, the PFAS levels of the incoming river water were measured at just 2.4-3.6 parts per trillion. Those concentrations are below the EPA’s standard even before the water got scrubbed.

Tungate points out that incoming water was not tested previously, and he contends that the authority has little control over its incoming water because the watershed of the Rivanna River’s north fork stretches beyond Albemarle into Greene and Orange Counties.

“We don’t control that run of the river,” said Tungate. “So we’re at the mercy of what’s upstream.”

While the North Rivanna plant was down for 16 days, the total system capacity was not diminished, Tungate says, due to the authority’s network of underground water supply pipes.

“We’re able to able to pull from one area to another,” he said. “That’s a benefit not many water authorities have.”

This water authority obtains its granular activated carbon system through a performance contract with Pittsburgh-based Calgon Carbon Corporation, according to Tungate. He says the utility spends about a $1 million annually with Calgon to keep about 555,000 pounds of the material working at the five local treatment plants.

On a recent tour of one of them, Tungate walked some visitors past two vessels that are at least thrice the size of the casks at any local winery. After various impurities have been removed in giant open-air pools, the nearly-cleaned water gets its final scrubbing by coursing past granular activated carbon hidden inside these giant metal vessels.

Tungate says that Calgon Carbon is now owned separately from the consumer products company known for its take-me-away bubble baths. And yet Calgon Carbon does visit Rivanna treatment plants to “take away” worn-out granular activated carbon and then return with fresher material.

Initially, the goal was to reduce the total organic carbon in the water, and every gallon getting scrubbed would reduce the longevity of the granular activated carbon.

“So to be good stewards of our customers’ money, we were operating this to maintain a total organic carbon goal of .75 milligrams per liter,” said Tungate. “But after what happened at North Rivanna, we said, ‘No, we’ve got to increase the flow.’”

Tungate says the authority would not have had this system in place without the voices of residents who expressed unease more than a decade ago about a proposal to disinfect local water with chemicals called chloramines. In 2012, the authority rejected chloramines and embraced granular activated carbon.

“It was a progressive decision made by the community,” said Tungate. “It set the stage for us to be forward thinking for other contaminants.”

He said that in addition to its ability to strip out total organic carbon and PFAS, the granular activated carbon system can also remove microplastics and pharmaceutical byproducts.

“We didn’t have any of those things in mind in 2012,” said Tungate. “But this was a very progressive decision. The community decided we’ll pay extra to have something better.”


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