“send 600 million gallons of acidic radioactive waste into surrounding neighborhoods.“

Why is it radioactive

I'm not sure, but from a cursory bit of searching the mining of phosphorous may include radioactive trace elements which might be removed or concentrated at various steps of the production of fertilizer. I found e.g., https://www.sciencedirect.com/science/article/pii/S168785071... and https://www.osti.gov/biblio/459030-issues-natural-radioactiv...

From https://www.eenews.net/stories/1062576963:

> Rising above the flat landscape of west-central Florida are towering ponds of acidic wastewater sitting atop mounds of a mildly radioactive material called phosphogypsum.

And https://en.wikipedia.org/wiki/Phosphogypsum:

> Phosphogypsum … [is] formed as a by-product of the production of fertilizer from phosphate rock … phosphogypsum is usually not used, but is stored indefinitely because of its weak radioactivity.

Because the ore phosphate is extracted from also contains uranium (and its decay products). Similarly, it contains a bunch of other nasty things, which at the sheer scale this stuff is produced and stored is a problem to handle.

All who aren't, should be aware that this Piney Point mine has been trouble since inception in the late 60s. The 'solution' of dumping the waste into the bay/gulf is becoming a pattern, eg 2003 (500mil gallons) and now again in 2021. In 2011, an accumulation of 170 million gallons of undumped waste 'leaked' into the bay.

This may be a truly difficult predicament, but a real solution is necessary.