Processing Magazine

Monsanto aims to stop leaks at Idaho mine dump

November 23, 2009
Monsanto Co. is installing a water management system at an Idaho phosphate mine the company depends on to make its Roundup weedkiller to stop the leakage of selenium and heavy metals into a tributary of the Blackfoot River, reports the Associated Press. The company hopes capturing runoff and underground water will remedy problems at the waste rock dump below its South Rasmussen Ridge Mine that have resulted in Clean Water Act violation notices from the federal Environmental Protection Agency. Monsanto is seeking federal approval for a new mine nearby, called Blackfoot Bridge, to supply the phosphate for Roundup; activist groups have demanded it first remedy old problems like South Rasmussen''s dump. The company says this water management system would have been built regardless of its efforts to mine elsewhere in the region near the Idaho-Wyoming border. Mines owned by Monsanto, the J.R. Simplot Co., and Canadian-based Agrium Inc. in Idaho''s rich phosphate belt have come under increasing scrutiny since selenium pollution began killing hundreds of livestock starting in the 1990s. None of the reported deaths have occurred at Monsanto mines. Monsanto''s water management system at its leaking dump will include shallow collection areas above the dump to capture rain- and snowmelt before it can seep into selenium-rich waste rock. It''s also adding drains at the bottom of the dump, to capture potentially contaminated groundwater before it reaches a nearby wetland and migrates further downstream. EPA officials toured the leaking dump in recent weeks to assess Monsanto''s water management system. The area''s complicated geology makes addressing problems a difficult proposition, but the EPA is optimistic these latest efforts will help reduce illegal releases of selenium, cadmium, nickel and zinc.