During a tour of the shuttered Columbia Falls Aluminum Co. on Thursday, Sen. Jon Tester, D-Mont., said he still hopes to see the site designated under the federal Superfund program and expressed skepticism about parent company Glencore’s resolve to fully remediate the property.

“The only way they got here was the EPA,” Tester said, referring to the federal agency’s proposal to list the site last year. “I’m afraid if it becomes a voluntary thing, they could walk away, or they could restructure.”

Since the company announced it was permanently closing the aluminum reduction plant in 2015, Tester has remained a proponent of adding CFAC to the National Priorities List.

Company officials have opposed the listing and argue the designation would unnecessarily delay the remediation work.

Tester said he was disappointed by Glencore’s failure to work with him years ago as he attempted to broker an electricity deal between the company and the Bonneville Power Administration that would allow it to remain open.

Once capable of producing 1 million pounds of aluminum per day, the plant has been closed since 2009. At its peak, the factory employed more than 1,200 employees, many of whom lived in the Columbia Falls area.

Among the local leaders and agency officials joining Tester was Columbia Falls City Manager Susan Nicosia, who said that regardless of the process, she simply wants to see the site cleaned up and repurposed into a new economic driver for the city of roughly 5,000.

In addition to the lost employment, she said the company’s closure was a substantial hit to the local tax base.

“It doesn’t directly impact the city, but it impacts the school district,” Nicosia said. “These were good-paying jobs, and we need to find a way to make this into a benefit to the community.”

Columbia Falls Mayor Don Barnhart has taken a more critical view of Glencore’s commitment to the property. He said after the tour Thursday that he appreciates the work the company has done in the past year, but believes it took the threat of the federal designation to get the company working toward a cleanup plan.

“It worked. They got put on the proposed list,” he said. “It’s a short road to Superfund listing at this point.”

Although he has previously endorsed the proposed Superfund listing, Barnhart commended the company for committing to a four-year, $4 million investigation of the site.

The investigation is slated to begin April 4 and will include drilling 43 new wells at varying depths, taking soil borings and analyzing surface water samples to determine the extent of contamination at the site.

The EPA’s previous site assessment detected elevated levels of heavy metals in the groundwater, including cyanide, arsenic, fluoride, lead and selenium.

EPA remedial project leader Mike Cirian said the agency will oversee the investigation work, which will be performed by a company hired by CFAC.

Describing the immediate steps as “reconnaissance work,” Cirian said they will be figuring out locations and methods for the sampling.

During a brief press conference after the tour, Tester said he does not support a possible “Superfund alternative” listing, which would hold the company to many of the same cleanup standards without officially adding it to the list.

“It’s just the right thing to do. I do not want to not have this cleaned up,” he said. “If you get the EPA to give it a clean bill of health, that’s money in the bank.”

The federal agency expects to make a listing decision this fall, but Cirian did not elaborate Thursday on what type of listing the federal agency is more likely to propose.

On April 5, EPA officials will hold a community meeting at Columbia Falls City Hall. It begins at 5 p.m. and will include a presentation outlining the remedial investigation process.