TAMPA – State authorities warned a fertilizer company a month ago that it was holding too much acidic wastewater behind a dike that was too thin atop a 180-foot-high gypsum stack.
Storm-driven waves broke through the dike Sunday, spilling millions of gallons of polluted water into a creek that feeds Hillsborough Bay. As the water release continued more than 24 hours later, the company raised its estimate from 41 million to 60 million gallons flowing into Archie Creek.
Hillsborough County environmental scientists said Tuesday that early testing showed that the spill raised acidity levels in the creek north of Gibsonton, but so far there was no evidence of an environmental problem in the bay.
The company, Cargill Crop Nutrition, worked Tuesday to raise the height of the dike made of phosphogypsum, an earthen byproduct of phosphate processing, while engineers considered measures to release more wastewater.
With Hurricane Ivan potentially following Frances, the state may order the company to treat and discharge as much of the water as possible.
A massive discharge is not an ideal solution. A caustic-soda treatment lowers the water’s acidity but does not remove nutrients such as phosphorus and nitrogen or heavy metals and harmful chemicals such as fluoride.
Florida’s Department of Environmental Protection told Cargill on Aug. 10 that a 100- foot section of the dike was 15 feet wide, short of the state-required 18 feet. The agency also warned that water in the reservoir atop the stack was too high; only an inch or two of rain would raise it to the top of the berm, the DEP wrote in a warning letter.
Cargill immediately started trying to thicken the dike, company officials said, but the work could not be completed in time. The berm gave way in the thin southwest section, the area the state had pointed out.
Gray Gordon, vice president of Cargill Crop Nutrition, said the dike was not thick enough because workers were trying to raise its height to cope with the water levels fueled by unusually heavy rainfall this summer.
“We didn’t have enough gypsum to build it up in a day or two,” Gordon said. “We were desperately trying to get as much gypsum as we could. And you can usually only run one bulldozer along the limited roadway.”
At Cargill and other phosphate processors, heavy equipment pushes the phosphogypsum into stacks that can reach 250 feet in height. Water used in the process is pumped into reservoirs at the top of the stacks.
State Suggested Safety Steps
The DEP sent Cargill another letter Aug. 31, saying the company should do everything possible to safeguard its impoundments in the face of Frances. The agency suggested that Cargill start discharging treated water and pumping to the top of an older stack across U.S. 41 – a stack closed since 1990 – for additional storage.
Cargill prides itself on recycling wastewater and does not have a discharge permit, as do most other phosphate operations. Gordon said the company did not discharge because it did not want to incur fines for doing so without a permit.
Also, Cargill did not think it had enough trucks with the amounts of lime needed to treat the water’s acidity. That proved accurate after the reservoir breach Sunday; at one point the company ran out of the treatment substance while water surged into the creek.
Cargill did respond to the letter by starting to prepare the abandoned gypsum stack for extra storage, Gordon said, but the company held off on pumping. “I don’t think we were delinquent,” he said. “But there was this discussion about … don’t automatically start pumping if this [storm] doesn’t come in. We wanted to try other options.”
Gordon maintains the spill would not have happened if not for the waves caused by Frances’ counterclockwise motion. He conceded engineers focused on the water the storm might bring, not waves.
DEP officials will take enforcement action unspecified at this point, spokesman Russell Schweiss said.
“Cargill could have treated and discharged some of this water because of the emergency situation,” Schweiss said. “They might have faced a fine for the environmental impacts, but in all likelihood, it would have been treated better than what it received” during the spill.
Environmental Effects Unknown
Richard Boler, a scientist with the county’s Environmental Protection Commission, said that although acidity is much higher than normal in the creek, levels appear near normal in most of the bay.
High acid levels can kill marine life immediately.
Boler said the storm surge might have diluted the wastewater in the bay, or it could have pushed the acid into mangroves and wetlands on the eastern shore.
There was no evidence of fish kills Tuesday, but Boler said it could take a day or two.
Reporter Mike Salinero can be reached at (813) 259-8303.