Taum Sauk operational for first time since ‘05 disaster
Written on May 4, 2010
AmerenUE said its Taum Sauk hydroelectric plant in Reynolds County is generating electricity for the first time since the mountaintop reservoir that fed the plant collapsed in 2005.
The 440-megawatt plant, about two hours southwest of St. Louis, has been out of service since Dec. 14, 2005, when a 700-foot section of the old reservoir wall collapsed, releasing more than a billion gallons of water that scoured Johnson Shut-Ins State Park and swept the home of the park’s superintendent off its foundation.
The new kidney-shaped reservoir atop Proffitt Mountain is almost a mile in circumference. It is constructed mostly of roller-compacted concrete, a material that is less prone to cracking and is now the standard construction material used in dams and spillways.
The new design incorporates redundant water-level sensors, continuous video monitoring and a spillway in case the reservoir is overfilled.
Taum Sauk is what’s known as a pumped storage hydroelectric plant, allowing AmerenUE to generate electricity within minutes compared with the hours it can take to start a coal-fired power station.
Water is pumped to the upper reservoir at night when electricity is cheaper, then released through a milelong tunnel to spin turbines that generate electricity during the day when demand is greater.
A 2006 investigation by federal regulators showed the failure of the upper reservoir was triggered when water flowed over the top and eroded the rock-fill dam. Water-level sensors that were supposed to prevent the reservoir from being overfilled had been moved too high to be effective.
In 2006, AmerenUE paid $115 million in penalties under a settlement with the Federal Energy Regulatory Commission. It also paid the state about $180 million to settle a lawsuit by then-Attorney General Jay Nixon. That money went to help clean up Johnson’s Shut-Ins and to extend Katy Trail State Park.
Not having the Taum Sauk plant available for the last four years has also cost AmerenUE millions of dollars in lost profit.
The utility announced plans to rebuild the plant in 2007. At the time, AmerenUE estimated it would cost $350 million and be operational by the fall of 2009. Instead, the project wasn’t complete until this spring, and at a cost of $490 million.
Almost all of the cost of rebuilding the upper reservoir will be covered by insurance, AmerenUE officials have said.
The state Public Service Commission has barred the utility from recovering any costs from customers.
Taum Sauk originally opened in 1963.
The plant’s 50-year operating license expires on July 1, 2010. In June 2008, AmerenUE applied to relicense the plant for another 40 years.
Filed in: term.