TAMPA - A Riverview phosphate company stabilized a dike over the weekend that ruptured Sept. 5 and spilled 65 million gallons of highly polluted wastewater into a nearby creek.
The dike at Cargill Crop Nutrition surrounds about 1 billion gallons of phosphate process water atop a 180-foot- high phosphogypsum stack. A 100-foot section of the dike broke after being buffeted for 24 hours by the high winds and waves of Tropical Storm Frances.
With Hurricane Ivan seemingly on track last weekend to hit the Bay area, government regulators worried that the dike could break again. The storm changed course, but there still is a chance outer bands of heavy winds and rain could put pressure on the dike walls.
Throughout the weekend, dump trucks streamed up and down the stack, carrying gypsum to be compacted on the dike by gigantic earth movers. Phosphogypsum is an earthlike substance left after phosphate is processed into fertilizer.
``Things were pretty frantic Friday night. That's when we thought Ivan was coming,'' said Rick Garrity, executive director of the Hillsborough County Environmental Protection Commission.
Government regulators also were concerned about another earthen dam, one around Cargill's 238-acre cooling pond. Water is heated during fertilizer production and cooled for reuse through a system of canals and ponds.
Florida's Department of Environmental Protection ordered Cargill on Friday to start reducing water levels in the cooling pond. To comply, Cargill is pumping the highly acidic wastewater back up to the phosphogypsum stack where the dike broke.
Just last week, though, the company was trying frantically to reduce water levels on that same stack. It accomplished its goal by pumping 32 million gallons to a swale, or big ditch, surrounding the stack and 30 million gallons to an inactive gypsum stack. The combined pumping lowered the water level to 4 feet below the top of the dike. The water surface had been 1.3 feet below the top of the dike when it broke.
``They're comfortable putting 70 million gallons back in the stack,'' DEP spokesman Russell Schweiss said.
Before Tropical Storm Frances hit, DEP had found Cargill in noncompliance with state regulations governing storage of process water. DEP issued a consent order Sept. 2 that found Cargill's Riverview site did not meet minimum design criteria for raising phosphogypsum stacks. The order also faulted the company for not having adequate storage capacity to safely manage process water.
The agency acknowledged, however, that unseasonably heavy rains this summer contributed to the ``emergency conditions.''
Those conditions included a dangerous erosion of the southwest section of the dike. DEP noted that the section, where the dike ultimately broke, was 15 feet in width, 3 feet less than required by state regulations.
As of Monday, Cargill had unloaded 88 truckloads of caustic soda to treat the water in the swale and the cooling pond. The caustic solution neutralizes the acidity in the process water. DEP ordered the company to start the treatment so the water can be discharged into Archie Creek if another spill occurs.
Also Monday, Cargill facilities in Bartow and Mulberry started discharging process water that ultimately will end up in the Peace and Alafia rivers. The Cargill sites had been among five phosphate plants that had reached ``must treat'' levels because of diminished storage capacity, according to DEP. The plants were ordered to start treating the water and discharge once they met federal water quality standards. The other plants were IMC plants in Nichols and New Wales and U.S. Agri-Chemicals in Fort Meade.Tampa Tribune/Mike Salinero