Photos: Cynthia Barnett and Mosaic Co. ? Reporting: Cynthia Barnett ? Infographic: Robb Brown
» The leftover sand is often returned to the mine to fill in part of the cuts. The clay slurry is pumped to enormous pits called clay-settling areas. The clay ponds cover 100,000 acres of Florida and make up 30% of mined lands. They are problematic for the industry. Eventually, clear water floats to the top and is reused. But even after three to five years, the areas are like giant pies: Crusty on top but the consistency of pudding inside. They cannot support development. They are difficult to farm. Industry scientists have worked for years to hasten the settling; find a commercial use for the clay; turn the areas into tree farms; or other ideas.
» An even more challenging leftover for the industry and its neighbors is phosphogypsum, a mildly radioactive waste from the fertilizer plants. It’s stored in flat-topped hills called “gypstacks” up to 200 feet tall. Florida has 25 gypstacks; most are just south of Lakeland. They must be constantly monitored to make sure their acidic water doesn’t seep into the environment.