Mosaic laser mapping reveals depth of radioactive sinkhole

By Rick Elmhorst, Anchor/Reporter
Last Updated: Monday, October 17, 2016, 5:10 PM EDT

Mosaic has released pictures and video of its use of high-tech gear to map the inside of the Polk County sinkhole that allowed millions of gallons of slightly radioactive water to flow into the aquifer.

  • Mosaic used laser tech to determine depth of Polk sinkhole
  • Sinkhole has released slightly radioactive water into aquifer
  • Company is testing residential wells in Bartow area

Mosaic said it attached laser-mapping gear called LiDAR to a 1,300-foot cable strung across the sinkhole, which is in a gypsum stack near Bartow, and then lowered the gear into the hole. The technology uses laser light to make a 3-D map of an object or area.

The company thinks the process was the first time the technology has been used in that way.

"As far as lowering it down into an empty space, I am not aware that that's been done. So this was all built to do specifically what we are doing up on the gypstack,” Mosaic Vice President for Operations Herschel Morris said Monday.

Morris showed off pictures and drone video of the process. He said the technology revealed that the hole is now 220 feet deep from the top of the gypsum stack. That means it goes about 30 feet below ground level.

The hole was thought to be deeper when it first opened, but since that time, a layer of gypsum has formed at the bottom of the hole. The gypsum acts as a type of plug at the bottom.

But it's a porous plug that still allows water to pass through.

Morris said Mosaic will use the laser map of the hole to determine how to pump a concrete grout mixture into the hole to form a water-tight seal. That process could cost up to $50 million.

The company continues to test well water at residences in the area. As of Monday, the company said 763 residential wells have been sampled, and 588 results have been returned. Water from 578 wells meet primary and secondary drinking-water standards, and 10 did not, the company said.

"Mosaic is absolutely committed to making this thing right,” Morris said.

Morris said the company might start pumping the concrete grout into the hole by December. He said the company hopes to have the process finished by next year’s rainy season.


A huge sinkhole at the Mosaic phosphate facility in Mulberry, seen from the air Friday, Sept. 16, 2016, dumped million of gallons of slightly radioactive water into the ground. (Sky 13)