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Injection Wells Explained, As Manatee County Approves Use At Piney Point

 View of the Piney Point gypstacks
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View of the Piney Point gypstacks

Manatee County commissioners recently voted to use an injection well to get rid of the remaining wastewater at the Piney Point phosphate plant.

Though the water would be treated first, environmentalists have raised concerns about pumping anything into the ground that has the potential to contaminate Florida's aquifer.

State and local leaders are looking into options after more than 200 million gallons of nutrient-rich water was recently pumped into Tampa Bay from Piney Point when a reservoir leak posed a catastrophic threat to the surrounding area.

WUSF's Jessica Meszaros spoke to Greg Rawl, a hydrogeologist whose company is based in Fort Myers, about injection wells, their efficacy and safety.

What are injection wells?

Injection wells are used commonly in the state of Florida for disposal of excess fluid, typically from domestic wastewater treatment plants. And they've been widely used. There are hundreds of them all over the state. They have occasionally been used for disposal of surface water runoff, as well as for disposal of industrial waste.

And how do they work? You drop some potentially treated wastewater down this well, and then what happens? Where does it go?

It would be pumped down the well down a casing to a deep aquifer that is confined from the overlying potential drinking water aquifers.

So that means it potentially would not affect drinking water, right?

Correct, and all of these wells are permitted through the Florida Department of Environmental Protection. And they also have monitoring wells that monitor the overlying potential drinking water aquifers to ensure that there is no contamination. They also do extensive testing during construction, as well as post construction to ensure the integrity of the wells.

Manatee County commissioners voted to treat the remaining water on Piney Point before pumping it into an injection well. We know one of the ponds is full of nutrients and the other two ponds are said to contain some heavy metals and slightly radioactive gypsum. Could all the water be successfully treated before being sent into an injection well?

It can be treated. The only question is: what is it going to cost — which is going to be a function of what the concentrations are and what the contaminants are. And that would be something that would be looked at by the DEP in the permitting process.

In your opinion, is this the best way to get rid of all those millions of gallons of wastewater on Piney Point?

It is one method. Is the best? Usually, if you can reclaim the water and reuse it without, you know, causing degradation of wherever it's being reused, that's your best option. And state water policy typically tends to enforce or recommend reuse. It is a viable means by which to deal with this excess fluid.

Some people are concerned about putting this wastewater into injection wells and oppose this idea. Is there reason for concern about doing this?

As long as it's properly designed and constructed and monitored for follow-up, no.

Copyright 2021 WUSF Public Media - WUSF 89.7. To see more, visit WUSF Public Media - WUSF 89.7.

Jessica Meszaros is a reporter and host of Morning Edition at WUSF Public Media, and former reporter and host of All Things Considered for WGCU News.