Mosaic spill not expected to reach Hillsborough, official says
The spill of 215 million gallons of contaminated water from a Mosaic phosphate plant into the Floridan Aquifer is not expected to affect Hillsborough County anytime soon, and quite possibly not ever, a Hillsborough County Environmental Protection official said Wednesday.
The Mosaic New Wales plant, which processes phosphate rock that’s mined elsewhere into fertilizer, is a little more than a mile east of the Hillsborough-Polk county line.
Processed waste water leaked from a storage pond on the property down into the Floridan Aquifer, the underground source of drinking water for millions of Floridians, through a 300-foot-deep sinkhole last month.
The flow of the aquifer in that area is to the west-southwest towards Hillsborough, according to Sam Elrabi, water division director for the Hillsborough Environmental Protection Commission. But he said a couple of factors are expected to keep it from reaching Hillsborough.
First, the flow is very slow. Absent other efforts to keep the contaminated water from going off-site, it might take up to two years for the contaminated plume to reach the Hillsborough County line, Elrabi told Hillsborough County commissioners.
But it’s not expected to get even that far. That’s because Mosaic has two wells, one of them 800 feet deep, pumping up 11.5 million gallons per day to keep the plume of spilled waste water from spreading beyond the plant.
“We are seeing as predicted,” Elrabi said, that the well is picking up the contaminants that went down the sinkhole and “that the plume is held on site.”
“As long as they’re pumping, nothing of that plume theoretically will travel off-site,” he said. Similar pumping after a major sinkhole in 1994 also kept contaminated water from moving away from the property.
There are clusters of monitoring wells around the plant, and those will pick up any indication of movement toward Hillsborough, Elrabi said. And the EPC, which has met with Mosaic executives and state regulators, expects to monitor groundwater in the area, the plant and its cleanup for years to come.
Mosaic has offered to pay for tests of neighbors’ wells and to provide bottled water in the meantime. About 70 of the plant’s neighbors have asked the company for the tests and water. The nearest resident lives about 3 miles away.
On Tuesday, Mosaic executives apologized for not telling the public about the sinkhole for three weeks.
"We deeply regret we didn't come forward sooner," Walt Precourt, Mosaic’s senior vice president of phosphate, said in Polk County, where he and a colleague spoke at and after a County Commission meeting. "Any explanation about why we didn't (come forward) would ring hollow."
The leak occurred after the 45-foot-wide opened under a gypsum stack at its plant in Mulberry on or before Aug 27.
After plant workers discovered the leak, Mosaic three government agencies: the U.S. Environmental Protection Agency, the Florida Department of Environmental Protection and Polk County. None of those agencies notified the public, either.
A DEP spokeswoman said state law doesn't require the state or the company involved to notify anyone until there's some sign the pollution has migrated outside the property where it went into the aquifer.
"Should there be any indication of offsite migration of contaminated groundwater, rules require the notification of affected parties," the DEP's Dee Ann Miller said in an email to the Tampa Bay Times. "However, to date there is no evidence of offsite movement or threat to offsite groundwater supplies."
An unknown amount of gypsum, a fertilizer byproduct with low levels of radiation, also fell into the sinkhole.
The pond is now drained, though polluted water can still be seen seeping from the gypsum stack and pouring into the sinkhole. And every time it rains, more contaminated water will drain into the sinkhole until it is plugged and filled. The acidic level of the water is roughly equivalent to vinegar or lemon juice.
Mosaic has estimated repairing the leak will cost the company $20 million to $50 million.