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CFAC makes its case for cleanup plan

by CHRIS PETERSON
Editor | April 28, 2021 6:50 AM

The Columbia Falls Aluminum Co. made its case for a slurry wall containment of waste at its defunct Superfund aluminum plant site last week in front of the Columbia Falls city council.

The council has shown displeasure with the company’s plan, saying it wants to see hazardous waste on the site removed entirely.

The former aluminum plant, which has been torn down save for a few buildings, has an ailing landfill and former wastewater ponds at the north end of the property that show high levels of cyanide and fluoride in the groundwater.

The company recently released its preferred plan for cleaning up the waste, which calls for containing the old landfill and ponds with a slurry wall, as well as cleaning up contaminated soil at the site.

The total estimated cost of the slurry wall plan is about $50 million, project manager John Stroiazzo said in an interview after the meeting. About $46 million is the cost of the wall itself, which would be a wall 3 to 6 feet thick and 100 feet deep designed to contain groundwater from leaching from the site.

In contrast, a new onsite landfill, which would remove and re-bury the waste in an approved dump, has an estimated cost of $148 million.

Right now the contaminated groundwater flows toward the Flathead River, though levels of cyanide and fluoride, tests have shown, are far lower once the water gets to the river. The contaminated groundwater, to date, has not shown up in residential wells in the nearby Aluminum City neighborhood. The company ranked several different alternatives and removing the waste was rejected because it claims it could expose the community even further.

Stroiazzo said the company did not complete a cost estimate of removal, but they did estimate it would take up to five years to remove the waste by truck. He said it would take about 60,000 truckloads to remove the estimated 1.6 million yards of waste. It would then have to be hauled to a hazardous waste landfill in Arlington, Oregon, all of which would presumably run through at least part of town.

It could be removed by rail, but it takes specialized cars that the company would have to provide, he said.

But councilmembers didn’t seem particularly impressed with the slurry wall remedy. They asked no questions after a presentation by company officials, but afterwords, they expressed concerns about the longterm viability of the wall — say 100 years into the future.

“Walls crumble, Mother Nature attacks,” councilman Mike Shepard, a former plant employee, said.

Stroiazzo said the company examined statistics on 86 slurry walls used at other Superfund sites.

“From what we can tell, all of them worked,” he said.

The Hungry Horse News did find some analysis by the EPA on slurry walls. One 1998 study looked at 36 walls. The findings were somewhat vague. Of the 36 sites, eight had met objectives, 17 “may have” met objectives and seven “may not” have met objectives.

One key in the use of slurry walls is monitoring of water both inside and outside of the site, to tell if there’s been any longterm migration, the EPA noted in its study.

CFAC’s plan includes monitoring wells. In a 2002 EPA study, it looked at fewer samples of walls, but it noted they were working as designed. Montana has a wildcard, however — earthquakes —temblors in the state are not uncommon.

The draft feasibility study is expected to be released by the EPA at the end of May. It will then go through a round of public comments.

The EPA would take public comments into account, and issue a record of decision after that, late this year or early next year. There’s another unknown as well — who will actually pay for cleanup. CFAC is owned by Glencore and is suing the former plant owner, ARCO, for cleanup costs. The legal action is allowed under the Superfund law to determine who the “potentially responsible” parties are.

ARCO is owned by British Petroleum. Both companies are giants in the industry and they’re scheduled to square off in front of federal District Court Judge Donald Molloy at a bench trial in June.

Molloy will ultimately decide the culpability of both companies in the matter.