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Filling sinkhole taking longer than expected, Mosaic says

Phosphate giant Mosaic expected to be finished by now with filling in the massive sinkhole that opened up at its Mulberry processing plant last August. But it's not.

Company officials announced Wednesday that the hole beneath its phosphogypsum stack is wider than they had thought — 80 to 100 feet wide, instead of 45.

That means it will take a lot more grout than expected, which means completely filling in the hole will take longer. No one knows how much longer.

"We really can't forecast a date," David Jellerson, Mosaic's senior director for environmental and phosphate projects, said during a news conference.

Another factor: the weather. Now that the rainy season has started, Mosaic has sometimes had to pull its workers off the site because of lightning and wind risks, he said.

The cost to fix the sinkhole is likely to go up by an unknown amount, company spokeswoman Jackie Barron said. Officials initially estimated the cost to range from $20 million to $50 million, and more recently they raised that to $70 million, Barron said.

Jellerson said the larger size of the sinkhole became clear as the company drilled out more and more of the hole to pour in grout.

Meanwhile the recovery well has been pumping 4,200 gallons a minute out of the aquifer trying to recover all the pollution that fell in, he said.

The company is certain that it has contained the contamination on its own site, he said.

State Department of Environmental Protection officials told Mosaic it had a week to provide a new timetable for cleaning up the 215 million gallons of contaminated water that fell into the aquifer when the sinkhole opened.

A consent order, signed by the DEP and Mosaic in October, required the company to put up $40 million in financial assurances to guarantee it would fill the sinkhole.

If it fails to follow through on the entire order, the company will face fines of up to $10,000 per day.

Mosaic did get some good news. A federal lawsuit filed against Mosaic last year by neighbors was dismissed this week. After meetings at which Mosaic shared well monitoring data and other information, the neighbors agreed to drop the case, according to court papers.

This was not the first sinkhole to occur at the Mulberry plant near the border between Hillsborough and Polk counties. Another one, 200 feet wide and 100 feet deep, opened up there in 1994.

The new one opened on Aug. 27, gulping down the lake full of contaminated water that pooled atop the phosphogypsum stack. The acidic water that fell into the hole was laced with sulfate and sodium. The acid level is roughly equivalent to vinegar or lemon juice. An unknown amount of gypsum, a fertilizer byproduct with low levels of radiation, also fell in.

Jellerson said so far they have seen no indication of further sinkholes developing.

Times senior news researcher Caryn Baird contributed to this report. Contact Craig Pittman at craig@tampabay.com. Follow @craigtimes.

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