Crews are hauling dirt to the hardened edge of a fertilizer waste mountain in Louisiana and pumping out part of an acidic lake on top, hoping to stop the gypsum’s outward creep and prevent a potential disaster.
Mosaic Fertilizer LLC near Donaldsonville reported the problem Jan. 10 to state and federal authorities.
Part of one hard side of the 200-foot-high (60-meter-high) pile is moving an average of a half-inch (13 millimeters) a day, though in fits and starts from place to place, state Department of Environmental Quality spokesman Greg Langley told The New Orleans Advocate.
The moving section is about 1,000-foot-long (305-meter-long) and makes up about one-third the length of that side, company spokeswoman Callie Neslund said Thursday. The bulge is about 12 feet (3.7 meters) out at its farthest point, making it difficult to see, she said.
The pile’s top incorporates a 140-acre (57-hectare) lake of wastewater – about the size of 68 square city blocks.
If the gypsum stack were to give way and release what Mosaic calls “process water” into nearby wetlands, it “would be a world-class environmental disaster,” Louisiana Sierra Club spokesman Darryl Malek-Wiley told Nola.com The Times-Picayune.
The water is about as acid as vinegar or lemon juice and is considered a hazardous material, Russell Schweiss, Mosaic’s vice president of mine permitting and land permitting, told The New Orleans Advocate.
“It’s not something we want to see moving off-site, and we’re going to take the countermeasures necessary to ensure that doesn’t happen,” he said.
Schweiss said crews began draining the water Jan. 14. The pond was believed to hold about 720 million gallons (2.7 billion liters), and workers are removing about 10 million gallons (37.8 million liters) a day, he said.
The water is pumped to the top as slurry. The gypsum settles out and dries hard, Neslund said. The water is treated and re-used.
Neslund said crews initially were pumping it into a new “cell” of the waste area but are now moving it into a large reservoir.
Other crews will shore up the edge of the pile by dumping 150,000 cubic yards (114,700 cubic meters) of dirt alongside it. As a comparison, 169,000 cubic yards (131,820 cubic meters) of concrete went into the Superdome.
Neither Schweiss and Ron Yasurek, Mosaic’s general manager of phosphate operations, nor state regulators could say for certain how long it would take for the company’s measures to work, or if they definitively would, The New Orleans Advocate reported.
Schweiss said company official are also waiting on an analysis of the lake’s bottom for a better idea about how much water to pump out.
Engineers have learned that a layer of the subsoil 95 feet (29 meters) below the surface has sheered off from the lower depths and is bringing the gypsum wall with it, Schweiss said.
Mosaic Co. has had other environmental problems. It made a $2 billion consent agreement with the U.S. Environmental Protection Agency, the U.S. Justice Department, and state environmental agencies to settle a 10-year court fight over gypsum waste disposal in Louisiana and Florida. That included payments of a $5 million federal penalty and about $1.5 million each to Louisiana and Florida, and a trust fund to be used to cover the eventual costs of closing the Donaldsonville plant and three in Florida.
Terms of that settlement were among reasons the company had to file the Jan. 10 notice, Nola.com and The Times-Picayune reported.
Mosaic announced in May that it had completed an $84 million repair of a sinkhole below a gypsum stack in Mulberry, Florida, where the limestone geology is liable to sinkholes. It said the incident had no effects outside its own grounds.
It was a minor environmental problem but a major public relations disaster, The Lakeland Ledger reported.
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