Florida officials race to drain huge wastewater reservoir before potential collapse

Photo of port manatee from above
Port Manatee, where wastewater from a leaking reservoir is being drained (Image credit: Getty/Tinik)

Late last week, a significant breach in the wall of a wastewater reservoir in Piney Point, Florida, threatened to spill hundreds of millions of gallons of tainted water into nearby communities.

The water contains high levels of phosphorus and the nitrogen, which can affect water quality, and should the reservoir completely collapse, the ensuing flood would surge through local homes and businesses and could potentially become contaminated by radioactive waste materials stored at the reservoir site, the Bradenton Herald reported

To prevent this potential disaster, officials began pumping wastewater out of the reservoir and into Port Manatee, a seaport that lets out into Tampa Bay, the Tampa Bay Times reported. The pumping began on March 30, and by April 4, an average of 35 million gallons (132 million liters) of water was being dumped into the bay each day. The water being dumped is not radioactive.

The plan is to completely drain the reservoir into the bay and into "large storage containers," Acting Manatee County Administrator Scott Hopes said April 4, according to the Tampa Bay Times. 

"We're not out of the critical area yet," Hopes said. Should the reservoir collapse, "all of the models show it would take less than an hour for it to drain out, in as high as a 20-foot [6 meters] wall of water," he said.

Related: Lessons from 10 of the worst engineering disasters in US history

What's in the water? 

Officials originally reported a leak in one of the ponds at the Piney Point reservoir on March 26, when they found water flowing from the pond at a rate of 2 million to 3 million gallons (8 million to 11 million liters) per day, according to The New York Times. The 79-acre (32 hectares) pond mostly holds salt water that was dredged from Port Manatee, as well as rainwater, stormwater runoff and "process water" from the now-defunct Piney Point phosphate plant, the Bradenton Herald reported. 

The phosphate plant originally opened in 1966 to manufacture fertilizer, and it operated for 35 years, according to the Herald. The fertilizer manufacturing also produced a waste product called phosphogypsum, which contains radioactive materials, including uranium and radium

The leaking wastewater pond sits atop a "stack" of this phosphogypsum, and although the water itself is not radioactive, a sudden breach of the reservoir wall could topple the stack underneath and send radioactive material streaming into nearby communities and waterways.  

The leaking pond also sits near two additional wastewater reservoirs, according to the Tampa Bay Times; should the leaking pond collapse, some experts worry that the freed water would wash over these nearby ponds and release hundreds of millions of additional gallons of contaminated water.    

The wastewater from the leaking pond "meets water quality standards for marine waters, with the exception of pH, total phosphorus, total nitrogen and total ammonia nitrogen," the Florida Department of Environmental Protection announced, according to The New York Times. "It is slightly acidic, but not at a level that is expected to be a concern, nor is it expected to be toxic."

On March 26, the leaking pond held 480 million gallons (1.8 billion liters) of water, The New York Times reported; by April 3, only 390 million gallons (1.5 billion liters) remained. Engineers attempted to plug the leak on April 2 and 3 but did not succeed. 

Upon closer examination, the engineers noted that "a portion of the containment wall at the leak site shifted laterally, signifying that structure collapse could occur at any time, and so staff and personnel were evacuated from the site," Jacob Saur, the county's director of public safety, told the Tampa Bay Times. 

On April 3, Florida Gov. Ron DeSantis declared a state of emergency, which established a mandatory evacuation zone around the reservoir. More than 300 homes — as well as farmland, pastures and a natural gas plant that supplies millions of Manatee County residents with power — fall within the evacuation zone, according to the Tampa Bay Times. The Manatee County jail is also in the flood zone, but not all staff and inmates are being evacuated; some are just being moved to higher floors of the jail.

"Looking at the volume of the water that has been removed and the current stability of the current breach, I think the team is much more comfortable than we were yesterday," Hopes said Sunday (April 4), according to the Bradenton Herald. "With the addition of the pumps ... I think we're going to be in an even better position." As of April 4, less than 300 million gallons (1.1 billion liters) of water remained in the leaking pond, the Tampa Bay Times reported.

Although the wastewater from the leaking pond is not expected to be toxic, the sudden infusion of phosphorus and nitrogen into Tampa Bay could wreak havoc on local plants and wildlife.

For example, pollutants from lawn fertilizers, septic tanks and agricultural waste have fueled algal blooms in the Indian River Lagoon, an estuary on Florida's Atlantic coast, coating the water's surface with muck that prevents light from reaching seagrasses below, National Geographic reported. When those seagrasses died, it caused a ripple effect through the entire ecosystem and left manatees with too little food to survive. 

In the wake of the Piney Point disaster, "algae blooms followed by fish kills are the most likely thing," Matthew Pasek, a geoscience professor at the University of South Florida, told Axios. "It's going to impact the food chain further down the line, too. It's unlikely to cause human damage, but there's going to be a pretty stinky bay for a while."

The Piney Point reservoir has leaked several times in the past, according to the Bradenton Herald. In 2003, about 250 million gallons (950 million liters) of wastewater was dumped into the Gulf of Mexico to prevent an overflow at the reservoir, and in 2011, a pond breach sent a surge of wastewater into Bishop Harbor.

Originally published on Live Science.

Nicoletta Lanese
Channel Editor, Health

Nicoletta Lanese is the health channel editor at Live Science and was previously a news editor and staff writer at the site. She holds a graduate certificate in science communication from UC Santa Cruz and degrees in neuroscience and dance from the University of Florida. Her work has appeared in The Scientist, Science News, the Mercury News, Mongabay and Stanford Medicine Magazine, among other outlets. Based in NYC, she also remains heavily involved in dance and performs in local choreographers' work.