Giant ‘fish tank’ filters clean PFAS from MI’s first known site

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Filters at the former Wurtsmith Air Force Base in Oscoda clean PFAS from the water. (February 2018)

OSCODA TOWNSHIP, Mich. (WOOD) — It works like a giant fish tank filter, and it’s clearing out some of the likely carcinogen from Michigan’s first known PFAS site.

The question is whether the system being used at the former Wurtsmith Air Force Base in Oscoda, near Lake Huron, would work on Wolverine Worldwide’s PFAS spreading through northern Kent County.

The U.S. Air Force spent $3 million to build a PFAS treatment plant three years ago right on top of a contaminated plume of groundwater flowing from Wurtsmith.

The plume of the likely carcinogen starts below a fire training pit where Wurtsmith firefighters used PFAS-laced foam to practice putting out jet fuel fires until the early 1990s. The PFAS flows toward Clark’s Marsh not far away, where the fish are filled with the likely carcinogen.

“You can’t eat the fish. You’re not even supposed to eat even one of those fish,” Michigan Department of Environmental Quality specialist Robert Delaney said.

Residents complain the Air Force and state aren’t doing enough to clean the contamination discovered eight years ago. The chemical has also flowed off base in other directions and into wells.

At nearby Van Etten Lake, popular for swimming and fishing, PFAS foam often forms on the water.

“When the wind is blowing, occasionally you’ll see a chunk of it break off and roll up the beach, and the next morning you go out and part of it is still on the beach,” DEQ consultant Dale Corsi showed Target 8.

So far, though, it’s just the bad water flowing into Clark’s Marsh that the Air Force’s filters are cleaning.

Here’s how it works:

First, seven wells tapped 60 feet into the groundwater form an underground wall, kind of like a good defensive line in football.

Instead of getting through to the marsh, much of the water is sucked through those wells into a massive tank.

Then, it flows through two filters, each about as high as a two-story house and filled with 20,000 pounds of granular-activated carbon. They treat about 240 gallons a minute.

It’s the same kind of system used in fish tank filters, or in the whole-house filters Wolverine installed in hundreds of homes in Kent County’s Algoma and Plainfield townships with contaminated wells.

From there, the water is piped back underground and into the groundwater headed for the marsh. It comes out clean, said Ryan Morrish, site superintendent at Wurtsmith.

“Nondetect,” Morrish said.

Every three months or so, Morrish said, Calgon Carbon vacuums out the coal from one of the tanks and incinerates the PFAS out of it at a cost of $30,000 per trip.

More proof that it works, Morrish explained, is that when the filtering started, the water came into the plant with a PFAS count of 10,000 parts per trillion — far above the danger level. Now, it’s less than half that.

“It’s working,” he said.

DEQ officials said they have started testing the marsh to determine if PFAS levels also are lower there.

“We know that the treatment system can only help, though,” DEQ spokeswoman Melanie Brown said.

The Air Force is on the front lines in the war on PFAS because so many of its bases are contaminated. It has identified more than 200 bases with potential contamination from firefighting foam.

“Hopefully, the technologies will keep advancing and so what’s the best technology today, two years from now, who knows what will be the best technology,” said Matt Marrs, the Air Force’s environmental coordinator for Wurtsmith.

They might look at coconut shells for carbon, instead of coal or maybe resin, which is being used to clean out PFAS at an Air Force base in New Hampshire.

DEQ officials said it’s too soon to know if any of this would work for Wolverine. It could depend on geology and what else is in the water.

“We’re looking at all sorts of options in Rockford, as in here,” DEQ spokeswoman Sue Leeming said. “We aren’t sure what the solution is going to be yet. We aren’t sure how effective those options are going to be or which will be best, but we’re going to work on it.”

>>Inside woodtv.com: Complete coverage of the toxic tap water investigation

Wolverine’s PFAS is from the Scotchgard it used to treat shoes at its tannery in Rockford. It dumped it in sludge at landfills and on farm fields decades ago.

The Wolverine PFAS zone has grown to 5 miles long and 5 miles wide, roughly twice the size of the Wurtsmith zone. It has spread into 400 wells in Algoma and Plainfield townships — some with the highest PFAS levels anyone has ever seen, far higher than levels at Wurtsmith. The levels are highest at Wolverine’s old tannery site and it’s leaking into the Rogue River.

Even with a three-year head start, the Air Force said its fish tank system isn’t a quick fix.  It could take years, the Air Force said.

Under pressure from the state, the Air Force plans to build a second treatment plant at Wurtsmith,, twice the size of the first, on top of another plume of bad groundwater. It plans to start using the plant in August.

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