FORT MYERS -- Florida Highway Patrol Troopers in Manatee and Hillsborough Counties have closed a portion of US-41 due to continued concern regarding the Piney Point Phosphogypsum Stack and waste water overflow.
US-41 is closed at 113th Street East in Manatee County and at College Avenue in Hillsborough County. Motorists desiring to travel south will need to detour onto College Avenue, travel east and access I-75. Motorists desiring to travel north should travel east on Moccasin Wallow Road and access I-75.
At 11 a.m. today (April 3) Manatee County officials ordered a complete evacuation of the Piney Point reservoir site. Evacuation notices were sent to any persons one mile to the north of the phosphogypsum stacks and a half-mile to the south.
Phosphogypsum is a by-product of the production of fertilizer from phosphate rock.
According to the Environmental Protection Agency, phosphate rock mining is the fifth largest mining industry in the United States in terms of the amount of material mined. The phosphate industry is concentrated in the southeastern United States. About 90% of phosphate is mined in Florida, North Carolina, and Tennessee.
Phosphate rock contains the mineral phosphorus, an ingredient used in some fertilizers to help plants grow strong roots, the EPA website explains. Phosphate rock contains small amounts of naturally-occurring radionuclides, mostly uranium and radium. When processing phosphate rock to make fertilizer, the phosphorous is removed by dissolving the rock in an acidic solution. The waste that is left behind is called phosphogypsum. Most of the naturally-occurring uranium, thorium and radium found in phosphate rock ends up in this waste. Uranium and thorium decay to radium and radium decays to radon, a radioactive gas. Because the wastes are concentrated, phosphogypsum is more radioactive than the original phosphate rock.
The waste that is created during fertilizer production is stored in large piles called stacks. Some stacks cover hundreds of acres and are hundreds of feet high.
Phosphogypsum is very watery when it is first put on the stack. As the phosphogypsum dries out, a crust forms on the stack. The crust thickens over time, reducing the amount of radon that can escape and helping keep the waste from blowing in the wind. Some of the water can leak out the bottom and pollute local groundwater, according to the EPA.