Columbia Falls Aluminum Co. officials released more data in a meeting Wednesday night that further pinpoints old landfills north of the plant as being the primary culprits for pollution at the Superfund site.

Tests taken last spring and summer show one test well near the former drum storage area and the wet scrubber sludge pond with concentrations of 5,000 micrograms of cyanide per liter. To put that in perspective, the Montana safe water drinking threshold for cyanide is 200 micrograms per liter. That one well has 25 times the cyanide that’s considered safe for drinking water.

Another contaminant in the water is fluoride. Like the cyanide, fluoride concentrations are the highest at that well, as much as 40,000 micrograms per liter, which is 10 times the safe water drinking threshold.

Roux Associates, the environmental firm doing the testing for the company, took 860 more samples over the past summer that included soil, surface water, groundwater and sediment from the 960-acre site, noted Roux hydrogeologist Mike Ritorto.

Ritorto said the additional data confirmed what the company suspected — that pollutants are flowing toward the Flathead River, but not toward houses and private wells in the Aluminum City neighborhood.

Even the pollution flowing toward the river falls off dramatically, the data shows. The cyanide levels in the groundwater drop as it flows south. By the time it reaches the river bank, the concentrations are below the safe water drinking threshold, at 100 micrograms per liter. Some wells near the river don’t detect cyanide at all.

The data further bolsters CFAC’s case against former owner Atlantic Richfield Co., noted CFAC manager John Stroiazzo. CFAC recently filed suit against ARCO, claiming in federal court that the company was, at least in part, responsible for the pollution since it dumped spent potliner and other waste on site when it owned the plant.

CFAC did not use the landfills causing the pollution when it operated the plant, the company claims. CFAC shut down the plant for good in 2009.

The federal Superfund law allows companies to seek damages against previous owners of the sites.

The plant itself is all but demolished. Crews from demolition contractor Calbag Resources have torn down all the old potlines and should have the basements filled in by the time snow flies. They’re using gravel mined on site for fill. The only buildings remaining are five silos and five other buildings the company retained, including a couple of warehouses, the former fabrication plant and the administrative offices.

The company hopes to find tenants who are willing to rent the warehouse and the fabrication shop. The fabrication shop is attractive because it has rail service right into the building. Stroiazzo said a company that repairs railcars has shown an interest in the building, but there are no firm plans yet.

The silos could come down this fall or next spring. Calbag might have a buyer for the alumina ore stored in them. If it does, it will empty them first and then tear down the silos in the spring, Stroiazzo said.

When all is said and done, the plant, which was once the largest building in Montana, will be just one big flat pad of gravel.

The next phase in the cleanup is to write a draft characterization data summary report for the phase II tests that were completed this year. That will come next spring. A separate company, EHS Support, will then look at risk assessments both to the ecology of the site and risks to humans in the future.

The risk assessment should be done by late next year.

In 2020, a feasibility work plan, which determines the best way to clean up the site, will get underway, with a final report due to the Environmental Protection Agency in 2021. At this point, no further tests at the site are anticipated.

CFAC continues to test groundwater at several residential wells in the Aluminum City neighborhood to the east for cyanide and flouride. Flouride has been detected in some wells, but below safe water drinking levels. One sample detected cyanide at very low levels, but could not be repeated and was likely due to the methods use to make the test, noted Mike Cirian, project manager for the EPA.

The EPA is overseeing all the testing at the defunct plant and will ultimately sign off on the best way to clean it up.