The Florida Department of Environmental Protection (DEP) and The Mosaic Co. are keeping a close eye out for a possible liner tear at Mosaic’s New Wales south phosphogypsum stack.
The DEP said that Mosaic notified it on Oct. 20 that a review of site monitoring data and results from a piezometers indicated a change in water pressure within a limited area of the stack. DEP said this could be indicative of a potential liner tear. As of Oct. 26, DEP told Green Markets that the investigation is ongoing and the cause has not been confirmed.
DEP said that inspections and data submitted by Mosaic to date indicate there is no breach of the walls of the gypstack and no discharges to surface water. DEP also said there is no process water storage atop the gypstack system in the vicinity of the area with the reported change in pressure. It said Mosaic ceased stacking and process water storage operations in this area in 2022.
DEP said Mosaic is required to perform an investigation, which includes confirmation of the prior piezometer readings and whether there is a liner tear or other potential cause of the observed changes in gypstack water pressure readings in this area. Mosaic’s investigation is ongoing and DEP inspectors have been onsite to observe and monitor these operations.
In addition, DEP is requiring Mosaic to provide daily reports on any piezometer monitoring data at the site and status reports on the ongoing follow-up investigations. According to DEP, Mosaic planned to begin drilling operations to investigate the anomaly during the week of Oct. 23-28.
DEP said its regulatory investigation into this matter is also underway. DEP said it is reviewing all information to determine if there are any violations or necessary penalties or enforcement actions. This review includes all permit, rule, and reporting requirements.
Environmentalists told the Tampa Bay Times that a liner tear was believed to be the cause of the leaks at the phosphogypsum stack at the long-idled Piney Point plant in 2021 (GM April 2, 2021). At that time, DEP agreed to allow an emergency release of wastewater from the phosphogypsum stack after being warned by the site manager that process water was bypassing the wastewater management system and making its way into Piney Point Creek, which runs into Tampa Bay.
The 2021 leak made national news, and the controlled release of water was believed to have averted a potential breach that could have caused a major disaster (GM April 9, 2021). Thereafter, the state of Florida budgeted funds to permanently close the site (GM April 16, 2021). DEP announced on Sept. 23, 2023, that the first phase of the Piney Point gypstack closure was complete.