CFAC pollution plume flows south to Flathead River, not town

There’s a plume of pollution in groundwater migrating from old landfills from the Columbia Falls Aluminum Co. plant Superfund site, but the flow is toward the Flathead River, not toward homes in the Aluminum City neighborhood, preliminary tests have shown.

Aluminum City is a Columbia Falls neighborhood just west of the Superfund site. To date, no residential wells have tested positive for cyanide, though fluoride has been found in very low levels — lower than the standard for safe drinking water, noted CFAC environmental manager Steve Wright.

The first round of test results, done by contractor Roux Associates, was discussed at length during a CFAC liaison panel meeting Wednesday night.

All told, Roux completed hundreds of samples. Samplers drew water from 60 different wells and took surface water samples from nearby creeks, ponds and the Flathead River beginning last fall. They also did 95 soil borings. Roux continues to take samples this spring and will complete the sampling this June, during spring runoff.

The highest concentrations of cyanide and fluoride were found just north of the plant itself below the west landfill. This was not unexpected, based on historical data and anecdotal evidence from former plant employees, noted Mike Ritorto, a hydrogeologist with Roux.

“It’s information that jives historically with the site,” he said.

Cyanide and fluoride are both byproducts of the aluminum manufacturing process, and over the years, spent potliner was buried at the site, which contained both chemicals.

One of the hottest spots on the site is the former drum storage area. A monitoring well in that area found the highest concentration of cyanide on the site, at 7,320 micrograms per liter. The state safe water drinking threshold is, for contrast, 200 micrograms per liter.

But as the groundwater flow moves southward, the contamination levels drop as well. By the time the plume reaches the Flathead River, the cyanide levels are just above or even slightly below the safe water drinking water threshold, according to maps presented by Roux.

In fact, the cyanide levels meet the requirements of discharge permits set by the state Department of Environmental Quality, Environmental Protection Agency project manager Mike Cirian noted.

But there are some puzzling aspects to the results. While most of the cyanide found is nearly directly south of the landfills, they did detect cyanide — albeit at levels well below the safe water drinking threshold — in Cedar Creek north of the plant.

“That was unexpected,” Ritorto said.

More tests are planned for the creek.

Cirian cautioned the crowd of about 50 people at the meeting that there’s still plenty of test results yet to come.

“I’m not allowed to pre-judge what a remedy is,” he said.

But panel member Don Bennett said just looking at the results, he expected that things could have been much worse.

The pollution isn’t just in groundwater, either. The study found high levels of polycyclic aromatic hydrocarbon compounds, like benzo(a)athracene, in surface soils surrounding the plant. But farther away from the plant, they were found in low levels or weren’t detected at all. They’re common byproducts of the industrial process to manufacture aluminum.

The next steps are to complete the testing and begin work on baseline risk assessments for both humans and the site environment. That process alone will take a couple of years, with the first reports due out in 2019. The risk assessments basically determine the health threat level of the site.

The final plan on how best to clean up the site won’t come until 2021.

Who will pay for cleanup remains a looming question.

CFAC is footing the $4 million bill for the initial studies and the final cleanup feasibility study, but the actual cleanup costs may come from a previous owner, noted project manager John Stroiazzo of Glencore, CFAC’s parent company.

ARCO used to own the plant and is now owned by energy giant British Petroleum.