Mosaic sinkhole 152 ft. wide, depth still not known

Mosaic recently used LIDAR/sonar equipment to measure the sinkhole. This graph shows the sinkhole.

POLK COUNTY, Fla. (WFLA) – Mosaic officials say they still don’t  know the depth of a sinkhole that opened up at the Mosaic plant near Mulberry last month.

The hole opened up in August, but the public did not know about it until WFLA News Channel 8 broke the story.

On Monday, Mosaic officials released details about the size of the sinkhole, which ranges between 40 feet, and 150 feet in diameter at its widest point, and approximately 220 feet deep from the top of the gypstack. Mosaic recently used LIDAR/sonar equipment to measure the sinkhole. LiDAR is a remote sensing technology that uses light in the form of a pulsed laser to provide three-dimensional mapping.  This technology expedites the remediation process.

“Based on the survey results, the company now has a better understanding of the sinkhole dimensions – which is a critical step in remediating the sinkhole,” Mosaic said in a release. “We continue to work with closely with FDEP and continue to keep Polk County and Hillsborough County apprised of our efforts to remediate the sinkhole.”

It took an estimated 3 to 5 days to take the measurements. Mosaic does still not know the depth of the sinkhole, and until then, they cannot begin the process of repairing it. “Once we define what’s underneath it, and in the confining zone, we’ll know where to pump the concrete type material,” said Morris.

The process of filling the sinkhole could be very expensive. Mosaic’s CEO has previously estimated it could cost $50 million. They will not know the exact cost to fill the sinkhole until it is measured completely. Morris said they would start pouring a concrete-like material into the sinkhole in December. The goal is to have the hole completely plugged before next rainy season, May or June.

After remediation, it is unclear if Mosaic crews will ever be able to go near the ground and ever work safely in that area again.

News Channel 8 broke the story about the sinkhole, which is located at the New Wales plant off Highway 640, just south of Mulberry.  The giant sinkhole sucked hundreds of gallons of radioactive water from a gypsum stack and dumped it into the aquifer.

As of October 17, 763 have been sampled.  There are ten wells for which that showed signs of radioactivity. Morris said they were not related to the sinkhole. “It’s Florida. We have radioactive materials that are underneath the ground that are unrelated to our business. Also, there are other signature elements and molecules that go with our water and that’s not there [in the samples] so we know that’s not ours.”


Private wells near the sinkhole have been tested for contamination.

Some residents who live near the sinkhole have filed a federal lawsuit.





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