The flow of wastewater to Tampa Bay from the old Piney Point phosphate plant site dropped significantly by late Thursday, according to the Department of Environmental Protection, and a dive team identified a possible source for the leak that spurred an emergency in Manatee County.
An estimated 202 million gallons of polluted water have been discharged to the bay through Port Manatee, the state said. Crews had been draining water from the reservoir at a rate of 38 million gallons per day as of Wednesday. Some is being kept in other storage at Piney Point.
Flows to the port slowed to less than 5 million gallons a day by Thursday afternoon, according to a Department of Environmental Protection estimate. The discharge had actually stopped as of about 5 p.m., said Weesam Khoury, a spokeswoman for the agency. Regulators were hoping to get two companies in place at Piney Point to start removing some nutrients from the water before having to restart releases.
Their goal, Khoury said, is to lower levels of nitrogen and phosphorus in the wastewater, which are a concern for Tampa Bay. Excess nutrients could cause algal blooms that then lead to fish kills.
The reservoir has been leaking for more than a week. It previously contained roughly 480 million gallons of wastewater, which the state said is a mix of seawater from an old dredging project, rainwater and water that is a polluted remnant of the fertilizer industry.
Piney Point once was home to a fertilizer plant, and the land still holds stacks of phosphogypsum, a radioactive byproduct of the business. The Department of Environmental Protection says the wastewater is not radioactive.
As of late Thursday, the agency said, the leaking pond held about 232 million gallons of water.
The state recently sent out diving companies and submersible cameras and found a seam that had come apart in the reservoir’s plastic liner, according to the Department of Environmental Protection. Crews are trying to repair it, Khoury said, while also examining the rest of the liner for other breaks.
Workers for more than a week have hurried to drain the pond amid fears the leaking water would cause berms around it to collapse under pressure, sending a flood into the surrounding community. Evacuations were at one point ordered for more than 300 homes. Manatee County officials have relaxed their response, saying the risk of catastrophe has passed.
Gauging the environmental impacts on Tampa Bay, however, will likely take weeks. Regulators are checking water quality around Port Manatee and have reported elevated phosphorus levels near the discharge point.
The two companies looking to quickly treat wastewater at Piney Point are NClear and “phosphate free water solutions,” according to an email filed in state records from an employee of HRK Holdings, the site’s owner.
NClear is headquartered in Atlanta and on its website describes handling nutrients using “nanocrystal technology” and “electrochemical technology.” A company in Lakeland is called Phosphorus Free Water Solutions and says online that it addresses nitrogen using a “porous ceramic media ... in conjunction with locally sourced denitrifying bacteria.”
Khoury declined to describe the treatment in detail because she said the businesses’ methods are proprietary.