032019 Mosaic Gypsum Update

Mosaic Fertilizer recently stopped draining a giant threatened lake of acidic water atop its waste pile in St. James Parish that some feared could break open and release its hazardous contents to harm surrounding swamps.

The company says it's confident water levels in the lake have now dropped to a depth that make the remaining water very unlikely to escape the troubled lake even if a crack opens up in the mountainous gypsum pile.

But others aren't ready to give the "all clear" signal just yet.

State regulators said they'd prefer that Mosaic keep pumping down the lake, but don't have the authority to require it to do so because the U.S. Environmental Protection Agency is in charge.

Some experts contacted by The Advocate have also questioned the underlying analyses driving the decisions of the company and regulators because so much remains unknown.

Rune Storesund, a civil and geotechnical engineer at the University of California-Berkeley, said that "given the uncertainties associated with this situation, the prudent approach would be to lower the water levels so that" the safety level is, at a minimum, nearly double what the company says its current efforts have attained.

With a few brief stoppages since early to mid-January, the company had been pumping down the water in the 140-acre lake through large siphons into neighboring lakes on the 960-acre waste pile at the company's "Uncle Sam" complex outside Convent.

The efforts were part of an emergency bid to remove weight from the lake's northern containment wall and halt unexpected slippage of the 200-foot-high slope of waste gypsum that helps contain the lake.

With the pumping and the construction of an earthen berm designed to brake the slipping wall now finished, Mosaic says it's now preparing for the next phase of its response. This involves building a kind of levee through the length of the rectangular lake to separate the remaining water from the north wall, further reducing pressure on the slipping slope of gypsum. 

The gypsum is a largely unusable waste byproduct from Mosaic's production of phosphoric acid, which is used to make fertilizer for corn and other crops. The lake, which rests inside of bowl carved from the top of the massive mound of waste gypsum, contains trace amounts of heavy metals and radioactive elements.

Records show Mosaic has been presenting its plans to regulators since the emergency started. It's not clear, though, if any state or federal regulatory agency monitoring the emergency response specifically authorized Mosaic to stop pumping out the lake.

"We would not do it if we didn't have permission to do it," Callie Neslund, Mosaic spokeswoman, said Friday evening, shortly before the halt occurred.

But Greg Langley, a spokesman for the state Department of Environmental Quality, said the state agency would like the pumping to continue, at least while the slipping gypsum wall is still moving. It's been moving about 0.3 to 0.5 inches per day, on average.

He said the EPA is the lead agency responding to the two-month-long emergency.

Mosaic remains under a consent order reached with the EPA and the U.S. Department of Justice in 2015 over how the company previously handled the acidic water, known as process water, at plants and in Louisiana and Florida and also prepared for long-term closure of its waste piles. Mosaic agreed to pay a $2 billion settlement of longstanding alleged violations. 

An EPA spokeswoman said Tuesday that Mosaic didn't need the federal agency's blessing to halt pumping into the siphons draining the lake.

"Mosaic is not required to get EPA authorization to stop siphoning," said Jennah Durant, EPA spokeswoman. 

According to Mosaic's reports to regulators, the company has lowered the lake's water level by 13.4 feet since it started pumping in early January and reached a key threshold water level for safety, at slightly less than 180 feet above sea level.

At that height, the acid water — about 400 million gallons in all — remains 30 feet deep at its deepest point in the lake. That is believed to be below the depth that any potential crack could slice open the gypsum pile's wall.

Company officials and regulators can't say yet when the movement will halt, but Mosaic says daily monitoring data show the wall's movement has slowed.

EPA agrees with this assessment and, in late February, declared in a letter that the risk of a catastrophic failure of the gypsum wall and a release into the swamps is negligible.

Storesund, the executive director of the U.C. Berkeley's Center for Catastrophic Risk Management who is also a licensed civil engineer in Louisiana, has questioned this assessment.

Based on the publicly available reports on the Mosaic gypsum pile, Storesund said, it does not appear Mosaic or regulators have done the kind of advanced, and expensive, analysis to model with greater precision what is happening with the gypsum pile. 

He called the EPA's declaration that the risk of catastrophic collapse is negligible "a very dangerous line of belief" because the agency can't yet answer threshold questions about what is happening.

"You'll be lucky, or it's not going to end well," Storesund said.

Follow David J. Mitchell on Twitter, @NewsieDave.