Phosphogypsum Stack Expansion

Mosaic Fertilizer, LLC is proposing to expand its Riverview stack, located in Hillsborough County, by nearly 180 acres and fill roughly 35 acres of wetlands, ponds, ditches, and other water bodies to the west of its plant.

According to the US Army Corps of Engineers (ACOE) public notice, the project would affect aquatic resources associated with Archie Creek, North Archie Creek, Alafia River, and Hillsborough Bay. In its review, the Corps has made an initial determination that Mosaic’s expansion may affect threatened and endangered species, including green sea turtles, small tooth sawfish, manatees, wood storks, Eastern indigo snakes, and more.

The expansion project will be covered under the Fixing America’s Surface Transportation Act, Title 41 (FAST 41). This means an expedited environmental review process to permit the expansion of the existing phosphogypsum (gyp) stack operations.

The Army Corps' public comment period runs until March 19, 2026.

ManaSota-88 notes the following regarding phosphogypsum:

Until the industry can develop a method to prevent the dispersal of airborne radioactive particulates and until adequate impermeable liners are developed, no new gyp stack disposal areas should be permitted.

The inhalation of airborne gyp stack particulates is a potentially serious public health hazard. The specific activities of airborne gyp stack tailings are not being determined to assess the potential inhalation hazards. Insoluble alpha-emitting particles of respirable size will contribute to the risk of lung cancer. If the radioactive particles of respirable size are soluble, the bone-seeking radioisotopes (uranium, radium-226, and lead-210) will contribute to the risk of leukemia and bone cancer.

Runoff from phosphogypsum stacks causes serious problems. Gyp stacks can yield significant quantities of radium to surface streams and groundwater for years after the stack is abandoned.

Radioactive materials such as those found in gyp stacks may settle on soil or plants and may eventually be swallowed. Settled material may also be blown back into the air. People living near such facilities may also be exposed to direct gamma radiation.

A fence to keep people out of gyp stack areas will not suffice in light of existing information on the hazards posed by windblown particulates and radioactive gases.

Phosphogypsum from Central Florida has a high average radium-226 level of 33 picocuries per gram; additionally, chromium and cadmium levels in gyp stack cooling ponds routinely exceed EPA allowable concentrations.

A gyp stack dike failure can release contaminants to the subsurface; a stack failure can release contaminants to nearby surface waters. The combination of the intrinsic hazard of these wastes and the documented evidence of releases indicates that current management of phosphogypsum threatens human health through drinking water exposures, threatens aquatic life, and can render water resources unsuitable for consumptive uses.

We already know there are serious health risks associated with phosphogypsum. While EPA rules governing the use of phosphogypsum are weak, changes in the gyp stack can lead to much greater health risks caused by radon-222 emissions during the time the gyp stack is active.

At present, there are no federal, state, or local regulations that adequately protect the public from hazards associated with gyp stacks and ponds. There are no regulations that require the industry to make final disposition of phosphogypsum wastes in an environmentally acceptable manner.

The people of Florida, the tourists, and others who visit us make phosphogypsum waste disposal a national issue. Phosphogypsum is the radioactive and hazardous waste product of phosphate mining and fertilizer production. Continuing to ignore the health problems created by the phosphate industry will not make them go away but will merely add to their magnitude in the form of increased cancer rates and birth defects.

Because the phosphate industry is making a concerted effort to expand existing gyp stacks, which threaten human health and our air and water quality, independent scientists need to review the phosphogypsum stack studies submitted by Mosaic as part of this review process.

Phosphogypsum stacks can contaminate aquifers and include acids, radionuclides, arsenic, and other cancer-causing constituents. These wastes can exceed the state's pollution standards by as much as an order of magnitude.

The needless high risk that the public has incurred (one excess lung cancer per 1000) from air pollution emanating from these piles, the permanent loss of land use at these sites, and the long-term costs of oversight by federal, state, and local regulatory agencies to contain ground and surface water contamination, puts the negative economic aspects of this expansion in proper perspective.

The company is not providing a detailed assessment of the project. A detailed assessment must include long-term health effects, chemical interactions, and potential unit failures resulting from the proposed stack expansion.

Groundwater discharges from every phosphogypsum pile in Florida are either presently causing significant groundwater pollution problems or are expected to. The proposed gyp stack expansion will likely cause significant groundwater pollution problems because the clay liner under the stack will not stop all discharge of contaminants.

Groundwater discharges from phosphogypsum stacks can result from swelling of the clays and the displacement of certain substances, such as radium-226, from the clays. Thus, contamination of the surficial aquifer and water table aquifer is inevitable. Shallow wells in the adjacent area will be affected, as will adjacent surface waters receiving groundwater. Contaminants in the water table aquifer could eventually migrate into the potable Floridan Aquifer.

Conclusion

The ACOE should deny the Mosaic Fertilizer, LLC proposal to expand their existing gyp stacks for the reasons set forth above.