POLK COUNTY, Fla. — Phosphate mining company Mosaic is under the microscope yet again, after the Florida Department of Environmental Protection confirmed it’s investigating a potential tear in a liner under one of its gypsum stacks.


What You Need To Know

  • Mosaic investigating possible tear in liner in pit at phosphate plant in Mulberry

  • It would be the third issue with a leak at the company’s Polk County phosphate fertilizer manufacturing facility

  • Mosaic officials said crews will investigate the situation this week

The company released the information while filing a pollution notice with state environment regulators, saying monitoring data indicated a potential tear in a phosphogypsum stack liner, which could result in an indeterminate volume of process water released into the environment.

If the tear is confirmed, this would mark the third issue with a leak at the company’s Polk County phosphate fertilizer manufacturing facility. In 2016, a large sinkhole opened beneath a gypsum stack and resulted in 215 million gallons of contaminated water draining into the aquifer. Mosaic said in 2018 it had completed the huge task of repairing the massive sinkhole.

Following that incident, Mosaic put in place precautionary measures that included technology to detect seismic activity and changes in water pressure that could indicate another disaster on the horizon.

That’s what flagged a liner tear under a stack last year that caused a 300-foot cavity, and the potential for yet another just this past week. 

“We really have multiple third party experts that look at the seismic activity or any activity that’s going over the geophones to help us really determine what could be happening,” said Sarah Fedorchuk, Mosaic’s VP of government and public affairs. “And then the best steps forward to really pin down and then remediate anything that we have to.”

Fedorchuk said this scenario shows the precautionary measures the company put in place are working. She also said the area of the stack where the tear is suspected is not active and no process water is being stored above it. That water was drained in 2022.

Still, the stack itself could still contain water and environmental advocates worry it could contaminate area groundwater. Fedorchuck said safety wells are in place to capture and pump out contaminated water if that were to happen.