Evacuation orders were lifted on Tuesday for hundreds of residents near Tampa Bay in Florida as crews relieved pressure on the containment wall surrounding a leaky wastewater reservoir, reducing the threat of a toxic flash flood.
Residents and local businesses were permitted to return after data from the US Army Corps of Engineers showed a diminished risk of a catastrophic collapse at the site of the former Piney Point phosphate plant.
The Army Corps and local public safety crews have worked around the clock for days pumping hundreds of millions of gallons of water out of the reservoir to ease pressure on its weakened containment wall.
The crisis began last Thursday when officials discovered leaks in the structure, lined with tall stacks of phosphogypsum waste, an industrial byproduct from fertilizer manufacturing known to emit radon, a cancer-causing radioactive gas.
State environmental officials have said tests of water seeping from the reservoir showed it was not radioactive.
But local authorities nevertheless said they feared that an all-out, uncontrolled breach of the wall could unleash a 20-foot torrent of untreated wastewater into the surrounding area, and they ordered a mandatory evacuation of more than 300 nearby homes as a precaution over the weekend.
Florida Governor Ron DeSantis declared a local state of emergency on Saturday.
"We're now ending our fifth day since learning of a breach at the site, and I am in awe over the state, federal and local cooperation to ensure the safety of our residents," Manatee County Commission Chairman Vanessa Baugh said in a statement announcing the lifting of the evacuation.
While the pumping operation eased the threat to homes and businesses adjacent to the reservoir, the wastewater drainage was being routed into a nearby Gulf Coast seaport, posing environmental concerns there.
Ed Sherwood, executive director of the Tampa Bay Estuary Program, said pumping the nutrient-dense discharge into Port Manatee at the mouth of Tampa Bay could spawn algal blooms toxic to marine life in the estuary.