EPA says cyanide gas a concern with CFAC cleanup
This is one of the few buildings remaining at the CFAC site. The company and developer Mick Ruis announced an agreement for Ruis to purchase 2,400 acres of land at the former aluminum plant site, including warehouses like the one shown.
The prospect of physically removing waste from the former Columbia Falls Aluminum Co. site appears slim, according to data presented by the Environmental Protection Agency recently.
The EPA notes that in the final 2021 remedial investigation/feasibility study there is the possibility of releasing poisonous cyanide gas if spent potliner is dug up at the site.
Spent potliner contains cyanide and other metals. It’s the remains of the liner of the large pots where aluminum was smelted.
Up until 1990 or so, millions of tons of spent potliner were dumped at the plant site.
“It should be noted that spent potliner can be reactive with water in a way that produces toxic and explosive gases, which could further complicate this (excavation). Disturbance of the potliner-impacted material would release cyanide gas, a poison if inhaled. Swallowing cyanide via fugitive dust would also be toxic. Measures such as continuous air monitoring would need to be implemented during construction and, depending on the results of such monitoring, the need for enclosed work areas and/or limitations on exposed waste areas may need to be considered,” the feasibility study notes.
EPA officials pointed out that out during a recent public meeting that went over the feasibility study.
While there’s concern about cyanide gas, none has been etected in any of the several wells at the site, though there is cyanide in the groundwater. The EPA does not monitor for the deadly gas, as it doesn’t believe there’s an exposure route because the waste is buried, noted Beth Archer, community involvement coordinator for the EPA. Digging up the waste could release it, however.
The exposure to gas is another reason the feasibility study suggests it’s better to contain landfills and sludge ponds at the plant site with a “slurry wall.” And then put a protective cap over the dumps.
The wall, in theory, would be designed to keep hazardous wastes like cyanide, fluoride and arsenic that’s in the groundwater from migrating to the Flathead River.
But the idea of a slurry wall hasn’t proven popular with some Columbia Falls officials. They caution that walls can fail over time, and while such a plan would come with longterm groundwater monitoring, there’s also concern by local officials about who would assure that monitoring is done over decades.
The area is also prone to earthquakes, locals have noted.
City leaders note that without a full cleanup, the area would remain a dump, in essence, ad infinitum.
Cost is also at play.
A slurry wall has a price tag of just over $50 million.
Removal of waste — even if it’s removed and put into new landfills onsite — is extremely expensive.
It’s noted that there’s about 1.34 million tons of waste onsite.
Removing the waste offsite would amount to 4 or 5 years of trucking, the feasibility study claims, with about 70 truckloads a day, either by truck or by rail.
In fact, the feasibility study didn’t even put pencil to paper as far as what it might cost to haul the waste away to a hazardous waste — the closest one is in Oregon.
Debates about how best to clean up the site promise to continue.
The EPA recently said it has delayed its proposed action — another step in the Superfund process — until next spring.
The proposed action is a document outlining how the agency thinks is the best way to clean up the site.
Unlike the feasibility study, the proposed action is open to public comment and facets of it can be changed based on those comments.
After the proposed action is finalized, the EPA will release a record of decision, which is the final plan for cleanup.