Florida sinkhole causes radioactive water to leak into aquifer
bbc.co.uk
bbc.co.uk
The wikipedia article on phosphogypsum is not particularly reassuring:
...the marine-deposited phosphate ore from central Florida is weakly radioactive, and as such, the phosphogypsum by-product (in which the radionuclides are somewhat concentrated) is too radioactive to be used for most applications. As a result, there are about 1 billion tons of phosphogypsum stacked in 25 stacks in Florida (22 are in central Florida) and about 30 million new tons are generated each year.
https://en.wikipedia.org/wiki/Phosphogypsum
How long does phosphogypsum stay radioactive?
Phosphogypsum is radioactive due to the presence of naturally occurring uranium and thorium
The United States Environmental Protection Agency has banned most applications of phosphogypsum with a radium-226 concentration of greater than 10 picocurie/gram (0.4 Bq/g).
https://en.wikipedia.org/wiki/Isotopes_of_radium#Radium-226
The longest lived, and most common, isotope of radium is 226Ra with a half-life of 1,600 years. 226Ra occurs in the decay chain of 238U (often referred to as the radium series.)
With a half-life of 1600 years for Radium-226, quite a long time.