The Columbia Falls Aluminum Co. has filed suit against the Atlantic Richfield Co. in an attempt recoup costs associated with the cleanup of the old aluminum plant site north of Columbia Falls.

ARCO owned the plant, and dumped millions of pounds of waste into its surrounding landfills for decades, CFAC claims in a complaint filed in federal court earlier this month.

To date, CFAC has spent about $7 million in investigating and tests at the Superfund site and expects more expenses as a cleanup plan is developed.

Early tests, CFAC claims, have shown significant cyanide, fluoride and other contaminants near the former west landfill, the wet scrubber sludge pond, the center landfill, as well as percolation ponds near the former plant. Ground water near the landfills show high concentrations of cyanide and the ponds and surrounding soils show high levels of benzo(a)pyrene, which it claims is from cooling water used when ARCO owned the plant. Cyanide and fluoride has also been found in the surface water of the ponds, according to tests done by Roux Associates, the environmental firm hired by CFAC to study the site.

According to the suit, CFAC claims ARCO dumped 50,000 tons of spent potliner in the west and center landfills alone. The west and center landfills were closed in 1981 and CFAC never used either one, it claims in the suit. It also claims the landfill it did use when it operated the plant had a thick layer of clay both on the bottom and the top of the landfill and it only disposed of spent potliner on site for five years — from 1985 to 1990. After that, spent potliner was hauled off site to an different landfill.

Spent potliner is the carbon and other waste from the bottom of a pot used to make aluminum. It’s high in fluoride and cyanide.

Ownership of the plant goes back to 1955, when it was first built by the Anaconda Aluminum Co. In 1982, Anaconda merged with and into Arco, the suit claims. From 1955 to 1985 the plant produced about 3.5 million tons of aluminum. After 1985, Arco formed CFAC, also known as CFAC Montana, in 1985, which in turn, was bought by the Montana Aluminum Investors Corp. CFAC, as its now known, was created when the company merged and purchased all the shares of CFAC Montana.

“Arco’s production of aluminum at the site ... created several waste streams which Arco discharged onto the ground in various landfills, ponds and other areas of the site,” CFAC claims.

Meanwhile, the more modern CFAC created far less pollution, the suit claims, because it used a dry scrubbing process to clean air pollution and a different process to make aluminum, which was far more environmentally friendly, the suit claims.

For example, about 180 millions gallons of water from 1964 to 1977 was used cool spent potliner before transport to the landfills. That water was discharged into the northeast percolation pond.

CFAC in modern times didn’t use water to that extent.

In short, CFAC claims that Arco created most of the pollution at the site. It’s seeking a trial to recoup not only the costs of future cleanup, but what it spent to date.

In 2015, Arco was asked to pay for part of the cleanup when the site first became a Superfund site, but the company declined. The Superfund law, known formally as the Comprehensive Environmental Response Compensation and Liability Act, allows CFAC to pursue Arco for potential cleanup costs.

Today, Arco is a subsidiary of British Petroleum and CFAC is a subsidiary of the Glencore Corp.

The suit sets an interesting court battle between two giants in the extraction industry.

BP did not respond to requests for comment on the suit.