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A crew installs additional monitoring instruments Tuesday, Jan. 29, 2019, around the perimeter of a giant waste pile at Mosaic's Uncle Sam Plant facility in Convent. The 200-foot-high stack of phosphogypsum, background, supports and encases giant cooling ponds for process water used at the company's fertilizer complex next to the Mississippi River. A so-called "bulge" in formerly flat cane fields around the pile was the first sign that a wall of the gypsum, a byproduct of fertilizer production, was moving and threatening the stability of the pile and acidic water stored inside of it.