Work crews were pumping millions of gallons of contaminated wastewater into an ecologically sensitive Florida bay on Sunday, as they tried to prevent the “imminent” collapse of a storage reservoir at an old phosphate mine.
Officials in Manatee county extended an evacuation zone overnight and warned Sunday that up to 340m gallons could engulf the area in “a 20ft wall of water” if they could not repair the breach at the Piney Point reservoir in the Tampa Bay area, north of Bradenton.
Aerial images aired on local television showed water pouring from leaks in the walls of the retention pond.
Ron DeSantis, the Florida governor, declared a state of emergency after officials warned of the “imminent collapse” of the pond.
He toured the scene by helicopter on Sunday morning and said at a press conference engineers were still attempting to plug breaches in the reservoir wall with rocks and other materials, and that other mitigation efforts included the controlled release of 35m gallons daily at Port Manatee.
He said the state’s department of environmental protection (DEP) had brought in 20 new pumps.
“What we’re looking at now is trying to prevent and respond to, if need be, a real catastrophic flood situation,” DeSantis said. “The water quality issues that are flowing from this for us is less than the risk of everyone’s health and safety, particularly folks who may live in the area.”
The governor also attempted to downplay reports that the water contained traces of radioactive materials.
“The water was tested prior to discharge [and] the primary concern is nutrients,” he said. “The water meets water quality standards, standards for marine waters, with the exception primarily of the phosphorus and the nitrogen.”
Scott Hopes, the acting county administrator, warned at the press conference that despite a low population density, the nearby area could be overwhelmed by a sudden collapse of the 77-acre pond, even though discharges had lessened the quantity of remaining water.
“What if we should have a full breach? We’re down to about 340m gallons that could breach in totality in a period of minutes, and the models for less than an hour are as high as a 20ft wall of water.” he said.
“So if you’re in an evacuation area and you have not heeded that you need to think twice and follow the orders.”
Officials widened the evacuation zone late on Saturday from a dozen or so properties to more than 300 houses. The Tampa Bay Times interviewed some residents who were refusing to leave.
The pond at the abandoned phosphate mine sits in a stack of phosphogypsum, a radioactive waste product from fertiliser manufacturing. The pond contains small amounts of naturally occurring radium and uranium. The stacks can also release large concentrations of radon gas.
Nikki Fried, the Florida agriculture commissioner and the only elected Democrat in statewide office, warned of an “environmental catastrophe” and called on DeSantis – who described the toxic water as “mixed saltwater” in a tweet announcing the state of emergency – to hold an emergency cabinet meeting to discuss the state’s response.
“Floridians were evacuated from their homes on Easter weekend. 480m gallons of toxic wastewater could end up in Tampa Bay – this might become an environmental catastrophe,” she said on Twitter.
Environmental protection groups warned that more pollutants in Tampa Bay would heighten the risk to wildlife from toxic red tide algae blooms.
“Phosphate companies have had over 50 years to figure out a way to dispose of the radioactive gypsum wastes,” the activist group Mana-Sota 88 said. “At the present time there are no federal, state or local regulations requiring the industry to make final disposition of phosphogypsum wastes in an environmentally acceptable manner.”
In a statement, the group added: “The current crisis can be traced back to the absurd 2006 decision to allow dredged material from Port Manatee to be placed into one of the gyp stacks at Piney Point, something the stack was never designed for and should have never been allowed.”
At the Sunday press conference, Hopes conceded: “This could have been resolved over two decades ago.” He said the long-term objective would be to entirely pump out the three reservoirs on the site and fill them in.
The owner of Piney Point, HRK Holdings, bought the site after it was abandoned by the Mulberry Corporation, which operated the phosphate plant for more than 40 years. As long ago as 2003, the Sarasota Herald Tribune reported, reservoir walls were crumbling. The federal Environmental Protection Agency (EPA) previously authorized the dumping of hundreds of millions of gallons of toxic water into the Gulf of Mexico.
At a meeting of the Manatee commission on Thursday, called after the seriousness of the new leak became apparent, engineers pointed to the deterioration of the pond’s decades-old plastic liner.
“The condition of the liner is not particularly great,” Mike Kelley, an engineer commissioned by HRK Holdings, told the meeting, the Times reported. “It’s old. There were some installation issues. There’s a long-documented history of that liner system having issues.”
The newspaper inspected records of the site and found that staff documented small holes or weaknesses in plastic seams above the water line in July, October and December last year.