Missouri reviewing plan to treat waters after Taum Sauk reservoir failure

~ The deluge washed away muddy sediment that is now clouding the Black River.

ST. LOUIS -- AmerenUE officials are awaiting state approval of a plan to treat murky waters with chemicals after a mountaintop dam burst last month.

The company has proposed using chemicals in the lower Taum Sauk reservoir that will cause small floating particles of clay to bind together and drop to the bottom of the reservoir, said Mike Menne, vice president of environmental safety and health at Ameren.

The reservoir burst before dawn Dec. 14, sending about a billion gallons of water rushing down the side of Proffit mountain. The deluge flattened wide swaths of forest before washing away the home of Jerry and Lisa Toops, injuring their three children.

It also washed muddy sediment away that has clouded downstream waters in the Black River. Ameren officials say their plan to use chemicals is the most sensible way to deal with the problem.

"I would say this is our best shot of doing something relatively quickly," Menne told the St. Louis Post-Dispatch on Friday.

Menne said various chemicals could be used to address the sediment problem that have no effect on aquatic life and are not toxic to humans.

Kurt Schaefer, deputy director and general counsel at the Missouri Department of Natural Resources, said the proposal to use chemicals is still being reviewed. He said the state has also ordered Ameren to clean a rock-filled wall that normally filters upstream waters from the reservoir.

Meanwhile, the cause of the reservoir failure at Ameren's pumped-storage power plant remains under investigation.

Built in 1963, the reservoir received accolades as an engineering marvel. Ameren used two engines to pump water into the reservoir at night, filling it like a giant bowl. During the day, water was released through a channel to generate electricity.