Two hydrogeologists who had claimed the Mosaic Company and Florida Department of Environmental knew about rumblings of the 2016 New Wales sinkhole a year before it happened took back their statements made last week.
“They were right. I was wrong,” Don Rice said along with his wife Mary Hrenda in a phone interview Tuesday. “I made a mistake, Mary, too, and we regret the error.”
The admission came a day before the Manatee County resumes its public hearing on Mosaic’s request to expand operations at its Wingate East mine in East Manatee. The commission Wednesday will begin its third day of proceedings on the proposal.
While looking more closely into documents that proved they were wrong, hydrogeologists Rice and Hrenda found something else more alarming.
Originally, while looking through FDEP data on the 2016 sinkhole at the Mosaic Company’s New Wales facility in Mulberry, Rice and Hrenda found that in 2015, a suspicious spike in the water levels in the upper confining unit that sits above the Floridan Aquifer rose to 40 feet over a few months. This was recorded by a water level-detecting piezometer in the closed north phosphogypsum stack that had a sinkhole in 1994, whereas the sinkhole in 2016 happened at the south phosphogypsum stack.
When Mosaic responded by saying the spike in water levels was a reaction to grouting maintenance done between 2013 and 2015 on the “2013 anomaly,” the hydrogeologists dove into FDEP’s database called Oculus to find the evidence.
They found the work order that corroborated Mosaic’s and FDEP’s statements. But then they discovered information that they say showed the signs of a sinkhole at the north phosphogypsum stack in 2009, where a potential of at least 15 million gallons of residual process water had seeped through phosphogypsum material and leaked into the Floridan aquifer.
The chart they refer to shows the water level of the Floridan aquifer essentially mirroring the water level of the lower zone of the confining unit, which is indicative of a breach, the hydrologists said.
“The lower should act differently. It’s completely different,” Hrenda said.
A report from Ardaman & Associates stated that the rate at which water flowed from the phosphogypsum stack through to the Floridan aquifer was at five to 15 gallons per minute.
Through the hydrogeologists’ calculations, that means over six years, anywhere from 15 million to 47 million gallons of the residual process water from the phosphogypsum stack could have flowed into the Floridan aquifer.
Mosaic spokeswoman Jackie Barron said that from 1994 to 2016 at New Wales, there were only two sinkholes and two anomalies, or “subsurface erosion features” that don’t break the surface like sinkholes, including the “2013 anomaly” she believes they’re referring to.
She said Mosaic officials would have to review the documents that the two hydrologists were referring to before making a statement on the matter, but called the move an “11th hour revelation” ahead of the Manatee County commission meeting Wednesday and that the claim was “infuriating to be reckless” since they had been originally incorrect.
Andy Mele, the chair of Coalition to Stop Phosphate Mining, said that although it was reported to FDEP, the public was not notified and he still questions the state agency in how it has managed sinkholes.
“(FDEP’s) role is more germane than ever,” Mele said.