Company stops acid lake drain but environmental risk unclear

March 21, 2019

CONVENT, La. (AP) — A lake of acidic water on top of an unstable, mountainous pile of waste in Louisiana is now shallow enough that it is very unlikely water will escape and harm surrounding swamps, the company that owns the pile said.

Mosaic Fertilizer recently stopped draining the lake on its gypsum pile in St. James Parish, The Advocate reported Wednesday. Gypsum is a waste byproduct from Mosaic’s production of phosphoric acid, which is used to make fertilizer.

The company had been pumping down the lake into neighboring ones on the 960-acre (390-hectare) waste pile at its Uncle Sam complex outside Convent. It was part of a strategy to halt unexpected slippage of the 200-foot-high (60-meter-high) slope of waste gypsum that helps contain the lake.

State regulators say they would prefer that Mosaic keep draining the lake, but do not have the authority to require it because the U.S. Environmental Protection Agency has been leading the response to the two-month-long emergency.

However, EPA spokeswoman Jennah Durant said Tuesday that Mosaic did not need the federal agency’s authorization to stop siphoning the lake. And, Mosaic spokeswoman Callie Neslund said last week that the company would not have stopped pumping out the water without permission from regulators.

But the state Environmental Quality Department would like the pumping to continue, at least while the slipping gypsum wall that has threatened the lake since January is still moving, agency spokesman Greg Langley said.

Rune Storesund is executive director of the University of California-Berkeley’s Center for Catastrophic Risk Management and a licensed civil engineer in Louisiana. He said that because of the situation’s uncertainties, the prudent approach would be to lower the water level so the safety threshold is, at a minimum, nearly double what Mosaic says its efforts have achieved.

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


Information from: The Advocate, http://theadvocate.com

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