MULBERRY — The first sign something had gone wrong at Mosaic's phosphate plant happened on a Saturday. Workers on Aug. 27 checked the water level in a 78-acre pond of polluted water sitting atop a 190-foot phosphogypsum stack and discovered it had dropped by more than a foot.
At first, records show, they believed it was just the wind blowing the water around. But around 11 a.m. Sunday, they realized the level had now dropped 3 feet.
How could that happen? How could a pool of acidic water on top of a massive gypsum stack suddenly start draining away?
The answer: A sinkhole 45 feet wide and 220 feet deep had opened up beneath the stack. Down went 215 million gallons of contaminated water, gurgling into the aquifer that supplies the region's drinking water.
Although geologists say the reason should have been obvious, state records show that it took 10 days before Mosaic officials used the word "sinkhole."
As contaminated water continued pouring down into the aquifer, Mosaic and state officials both avoided using the "s-word." No Mosaic reports included it until Sept. 9. The public didn't find out until Sept. 15 — that's 19 days after the crisis started.
The Tampa Bay Times used state records to piece together a timeline of what Mosaic told — and did not tell — state and local officials about the millions of gallons of contaminated water that suddenly started disappearing into the earth, an incident that has set off legal and political waves across Florida.
Even the state's top environmental regulator said he didn't know it was a sinkhole. That's why he didn't tell Gov. Rick Scott about it until Sept. 16, the day after it hit the news.
"I knew at the time in late August that there was a water loss incident," Florida Department of Environmental Protection Secretary Jon Steverson told reporters last week. "I was not aware of the sinkhole until a much later point in time."
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On Aug. 28, seven hours after the company spotted the water loss, Mosaic officials called Steverson's agency. They did not use the word "sinkhole."
"Caller is reporting a release of phosphoric acid process water from a fertilizer manufacturing facility," the DEP noted. "The amount released and the cause are unknown and under investigation."
Phosphoric acid process water, stored in a pond atop the gyp stack, is a by-product of turning phosphate into fertilizer. It is a pollutant, but records show that at no point did anyone suggest notifying those who lived near the phosphate plant. State law does not require doing so until the pollution is detected beyond the polluter's property — a law the governor later declared "stupid" and vowed to change.
Two hours later, company officials emailed a written report to the DEP. Once again, no mention of the word "sinkhole." The acid process water spill wasn't mentioned either.
Instead, the email focused on an apparent tear in the gyp stack's polyethylene liner, installed beneath the stack to keep pollution from seeping into the aquifer.
"During routine inspections on August 28, 2016, Mosaic observed and confirmed a steady decline of water level in the West Cell of the South Gypsum Stack," the Mosaic report said. "This observation indicates potential damage to the Liner system in the West Cell."
Company officials estimated that 35 million gallons were pouring out of the pond each day. But they later noted there was "no visual feature/indication noted" that would tell them why.
Should Mosaic, the world's largest phosphate company, have known right away that the problem was a sinkhole?
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Robert Brinkmann, who literally wrote the book on Florida sinkholes, said yes. Despite not being able to see the sinkhole, Mosaic should have immediately known what it was dealing with, he said.
"If they knew there was a tear in the liner, they knew there was something draining that water down into the aquifer," said Brinkmann, a Hofstra University geology professor who wrote Florida Sinkholes: Science and Policy.
The answer also seemed obvious to George Veni, executive director of the National Cave and Karst Research Institute in New Mexico.
"It's a sinkhole!" Veni said. "By definition it's a natural depression in the surface and water that gets poured into it goes down to the bottom. It's a big hole in the ground."
Longtime Florida sinkhole expert N.S. "Sandy" Nettles laughed when he heard about Mosaic's reluctance to use the "s-word." Nettles, who used to work in the phosphate industry, said it's not uncommon for insurance companies to avoid the term too.
"That's just ridiculous," said Nettles, a Palm Harbor geologist frequently called as an expert witness in insurance cases. "I don't know who came up with the idea that if you don't call it a sinkhole, it's not a sinkhole. Things are still going down into the aquifer."
The fact that the liner tore, he added, "means it was probably leaking for a very long time."
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The experts said there's another reason Mosaic should have known it was a sinkhole: history.
Florida's limestone geology, known as karst, is so susceptible to crumbling that the state leads the United States in sinkholes.
One of the most notorious Florida sinkholes opened in 1994 at a Mulberry phosphate facility — the very same facility where the Aug. 28 sinkhole opened. That sinkhole — 160 feet wide and plunging 200 feet — also sucked the pond from a gyp stack into the aquifer, like water draining out of a bathtub.
That sinkhole opened 1¼-miles from the new sinkhole.
There have been other problems at that site. In 2004 and 2013, Mosaic "identified and then repaired … sub-surface erosion features" in its gyp stacks, Mosaic spokeswoman Jackie Barron said. In the 2004 case, a leaking pipeline caused erosion that could have caused another sinkhole.
That kind of history, the experts told the Times, should have made it clear to everyone working on the "water loss incident" what they were dealing with.
But even the DEP avoided using the "s-word."
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State inspectors arrived at the Mulberry plant within 24 hours of Mosaic's call. In an Aug. 29 report, the inspectors said they told Mosaic to hurry and build a well to pump out any polluted water that might have gone into the aquifer, to ensure it "would be captured and contained onsite." The well didn't start pumping until Sept. 10.
That means DEP inspectors were also aware the pond was draining into the aquifer, yet "sinkhole" does not appear in their report.
Mosaic workers began trying to pump water from the pond to another spot, but their pumps couldn't keep up with how fast it was pouring into the aquifer. By Sept. 1, the pond level had dropped by 11 feet. Meanwhile a Sept. 3 report to Mosaic and DEP by Mosaic consultant Ardaman & Associates also avoided using "sinkhole."
Instead, the consultant said the pond's disappearance "may have been caused by an anomaly likely connected to the Floridan aquifer system." Both Mosaic and DEP officials were officially calling it "the 2016 Water Loss Incident."
At last, on Sept. 6, more than a week after they first discovered the water drain, enough had disappeared that Mosaic officials spotted what they called "a fissure." That afternoon, all of the water was gone.
"Mosaic generally began referring to this as a sinkhole on Sept. 6 when we could see the hole," said Barron, the Mosaic spokeswoman. Nevertheless, a Mosaic letter dated Sept. 7 still called it the "water loss incident."
Mosaic finally used the word "sinkhole" in a Sept. 9 letter to the DEP and the federal Environmental Protection Agency. The EPA needed to know because, just last year, Mosaic reached two settlements with the federal agency to resolve claims about hazardous waste management practices at sites in Florida and Louisiana.
One of those sites was the Mulberry plant.
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The day after Mosaic first told the DEP about the mysterious leak, Mosiac sent a letter notifying Polk County officials about the problem. Mosaic, however, did not tell Hillsborough County officials, even though the Mulberry plant sits near the county line.
A Polk official later told the Lakeland Ledger that the way Mosaic worded the notice it "didn't seem serious."
Hillsborough officials were finally notified Sept. 7 — but they didn't tell the public either.
Finally, on Sept. 15, a WFLA-Ch. 8 reporter called Mosaic and the DEP to ask about rumors regarding the sinkhole. Only then did Mosaic make it public, and later apologized for keeping it quiet.
So far, more than 1,000 neighbors have demanded that their wells be tested for pollution.
Last week, Steverson told the Cabinet about a consent order his agency had worked out to guarantee Mosaic would clean up the pollution and fill the sinkhole.
He said he'd seen no signs of negligence, but if that changed, "we're going to protect the citizens and the resources of this state."
Editor’s note: A previous version of this story incorrectly stated the size of the fine Mosaic paid in 2015. Mosaic reached two settlements with the EPA to resolve claims about hazardous waste management practices at eight sites in Florida and Louisiana. The company agreed to pay an $8 million fine. It also committed $630 million which will grow to $1.8 billion to support the long-term care of phosphogypsum stacks on those sites. Mosaic also will fund environmental projects and capital improvements.
Times staff writer Jeremy S. Wallace and senior news researcher Caryn Baird contributed to this report. Contact Craig Pittman at email@example.com. Follow @craigtimes.