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BUTTE — The long-defunct Solvay site 8 miles west of Butte is about to see new life.

Work is underway to build a plant to process the dangerous phosphorous waste at the site. The plant, in a new 50x100-foot building, is scheduled to be up and running by summer 2020. It is expected to be built within a few feet of the concrete tank containing the hazardous waste.

Project site manager Dan Bersanti said that once the plant is processing the waste, it could bring approximately six to eight full-time jobs.

The waste — elemental phosphorous — combusts when it makes contact with air. For approximately 20 years, the 500,000 gallons of elemental phosphorous have been contained in the largely buried concrete tank at the site. About 2 to 3 feet of water, which is currently frozen, covers the waste to keep it wet.

The United Nations banned the use of phosphorous in munitions against civilians in the 1980s because it can burn at 5,000 degrees Fahrenheit.

The old Solvay plant — originally known as Victor Chemical Co. when it was built in the 1950s, then as Stauffer, Rhone-Poulenc, and finally as Rhodia before the plant shut down for good in 1998 — was torn down years ago. The Environmental Protection Agency and the Department of Environmental Quality raided the site in 2000, slapping the chemical company court with two federal felony counts of illegally storing hazardous waste.

Rhodia, which owned the plant then, pleaded guilty to both counts.

Belgium-based Solvay purchased the mostly moonscape-like 150 acres in 2011 and inherited its status as a Resource Conservation and Recovery Act site. Known more commonly by its acronym, RCRA, the EPA designation is similar to Superfund.

More than a decade after the raid, EPA decided last year to approve a plan to handle the waste. Solvay proposed the option to build a plant at a projected cost of $25 million to process the waste on-site. It is Solvay’s preferred plan.

Bersanti said the costs to build the plant could be as much as 50 percent higher than the original estimate.

Currently the site and plant are in design phase. By next spring, Solvay intends to begin grading the spot where the plant will go and demolishing some unused structures around the tank that holds the hazardous waste.

Once the plant is built, workers will excavate the waste material, picking up water along with the waste. The phosphorous will then be placed into a special container that will have water already in it to ensure the material doesn’t make contact with air.

The material will then be transported a short distance to a furnace where it will be heated to 700 to 800 degrees Fahrenheit. After being heated, recovered elemental phosphorous will be shipped off-site.

The phosphorous will travel to either of Solvay’s two North American locations. There is one in Charleston, South Carolina, and one in Canada, Bersanti said.

The phosphorous could also go on the open market, but Bersanti said the market for elemental phosphorous has mostly “gone away.”

When the plant was up and running, most of the elemental phosphorous processed in Butte went into detergent. Phosphorous has had a host of applications, including fertilizer and food products.

In a 2015 study that Solvay commissioned, the company reported that it could fill a "market niche" by becoming a host to processing outside phosphorous waste.

Bersanti said Monday phosphates are no longer used in detergents, and food-grade phosphoric acid is now made from other products.

But Solvay proposed the option of building a plant so it could potentially continue the plant's life and accept phosphorous waste from outside sources.

“That was always proposed, but our primary focus is on processing the material in the (tank),” Bersanti said Monday. “We’ll leave the option open. It might be something for the future.”

But if that happens, processing outside waste won't begin until all of the waste at the site has been processed, and that could take anywhere from five to seven years, with the potential to take as long as a full decade.

Once the waste is processed, a residue will be buried on-site. Bersanti said the residue will not be flammable.

Once the concrete tank is empty of all the elemental phosphorous waste, the residue will be placed into the tank, and the whole thing will be capped.

Bersanti said Solvay doesn’t need an air quality permit from DEQ for the furnace because the emissions will be “very slight.” DEQ confirmed this.

But, Bersanti added that the company will continue to work with DEQ to get a permit should one prove to be necessary.

The county is still negotiating the purchase of about 40 acres in one undisturbed corner of Solvay’s 150-acre site, Butte-Silver Bow TIFID administrator Kristen Rosa said. The county hopes to acquire the land to extend its railroad presence.

Because the site is an RCRA site, that complicates the negotiations, Rosa said Monday.

Montana Connections Business Development Park is a TIFID district, meaning the taxes stay within the district instead of going toward local government or the schools.

Rosa said that while she and the county support cleanup efforts at the site, any ongoing use of a new plant to process hazardous materials brought into Butte would need to be evaluated in the future when additional information is available. While it is the county’s goal to bring in new business, Rosa said Tuesday, “We do take into consideration the effect those businesses would have on the community.”

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Nat'l Resources / General Reporter

Environmental and natural resources reporter for the Montana Standard.

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