JEFFERSON CITY, Mo. -- Two former AmerenUE employees who monitored a mountaintop hydroelectric plant said computer readings showed nothing unusual about its water level on an early December 2005 morning, even though water was running over the top of its reservoir.
Attorneys quizzed the man who ordered the power plant to operate and the one who actually manned its computerized controls as the Missouri Public Service Commission on Monday embarked on its third week of investigatory hearings into the collapse of the Taum Sauk reservoir.
Utility regulators are looking into whether the reservoir failure -- which washed out Johnson Shut-Ins State Park and seriously injured the park superintendent's family -- highlighted a pattern of safety problems at the St. Louis-based utility.
Ameren already has agreed to pay $15 million under a settlement with federal energy regulators. A state Highway Patrol investigation led to no criminal charges from Attorney General Jay Nixon, who instead is pursuing civil damages in state court. The PSC's investigation is separate from the others, though Ameren attorneys have complained it's redundant.
James Bolding, then a power plant dispatcher at Ameren's St. Louis office, said he gave the orders to pump water up to the Taum Sauk reservoir and then ordered it to stop slightly below the targeted water level around 5 a.m. on Dec. 14, 2005. The intent was to drain the reservoir at 6 a.m. and sell the electricity it produced.
There was nothing to indicate anything unusual about the reservoir's water level, which was displayed on a 3-foot-by-5-foot plasma screen in his office, said Bolding, who now works for Ameren Corp.'s energy marketing subsidiary.
But just after 5 a.m., a 600-foot-wide section of the reservoir wall gave way.
Keith Mentel, who was operating the Taum Sauk plant from a control center in a Lake of the Ozarks dam more than 100 miles away, said he alerted the onsite Taum Sauk superintendent to a problem after his computers showed the plant had lost permission to generate power and the water level at the base of the mountain had risen. Only after that did Ameren discover the reservoir had breached.