The Tampa-based mining company Mosaic is looking to widen its phosphate waste pile in Hillsborough County in a sweeping expansion that would keep the facility open for another two decades, according to a federal notice and a proposal the company presented earlier this year.
The extension could stretch the towering mound of phosphogypsum, a mildly radioactive byproduct of the company’s fertilizer production, farther west toward U.S. Highway 41 and closer to the shores of Tampa Bay.
The plan, still in its early stages, would increase the gypsum stack’s total footprint by roughly 140 acres and make room for an estimated 48 million tons of gypsum storage, according to an initial estimate Mosaic gave in a company presentation earlier this year…