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Short Summary
Main recommendation: Treat pumped storage and large dams as high-risk systems that need a spillway and verified, on-site checks of water levels rather than relying on automated controls alone. The 2005 Taum Sauk failure in Missouri showed how a sequence of small oversights, including unreliable level sensors, a settling embankment, and no overflow spillway, could combine into a catastrophic breach. The Taum Sauk upper reservoir's failure is presented as a lesson for the wider dam safety field.
Key Points
- The Taum Sauk plant was a pumped storage facility that pumped water uphill overnight with cheap electricity and released it during peak demand, with about 70% round-trip efficiency.
- The upper reservoir was an off-channel ring dike on Proffitt Mountain, built with a rockfill embankment and a concrete parapet wall, and operated remotely with no on-site technicians.
- Cycling increased from about 100 to about 300 days per year after 1990s power market deregulation, while leaks had already been a long-running problem.
- A 2004 geomembrane liner fixed leakage but introduced new problems, including sensor conduits that became dislodged and gave readings lower than the true water level.
- Before the collapse, water had already overtopped the wall in September 2005; operators reprogrammed the set point to add more freeboard as a temporary measure, intending to make a permanent repair during the next scheduled maintenance drawdown, but the failure occurred first.
- The design had no spillway, and the failsafe probes were mispositioned and required both sensors to trigger before the pumps shut off.
Details Worth Noting
- Concrete instructions: The video gives no step-by-step procedure for an individual viewer. The actionable guidance for dam operators, as described in the video, is to ground-truth critical elevations (top of wall and all sensor levels) against electronic measurements, use on-site staff or closed-circuit cameras during the final minutes of daily filling, notify the regulator promptly after any overtopping event, include a spillway in off-channel reservoir designs, and verify that failsafe sensors are placed above settled embankment crests and trigger the shutoff independently.
- Settlement and material problems: The fill contained more soil than intended, and unsound foundation soils were not properly removed, so parts of the parapet wall ended up about 2 feet (600 mm) lower than at construction.
- Regulatory response: FERC fined the owner $15 million, the largest penalty it had issued at the time, with $5 million going to a fund for the area. Missouri settled for $177 million, much of which funded restoration of Johnson's Shut-Ins State Park, which reopened in 2010.
- Rebuild: The new dam used roller-compacted concrete, incorporated a spillway, and recycled crushed original rockfill as aggregate. It is described as the largest roller-compacted concrete dam in the United States.
- Industry changes: FERC required owners to have an internal dam safety program and a Chief Dam Safety Engineer, and issued task force guidance on pumped storage.
- Human impact: The park superintendent, his wife, and their three children (including a seven-month-old) were swept away when their house was destroyed, but all survived despite injuries and hypothermia. The failure happened in winter when the park was practically empty, so there were no other casualties.
Bottom Line
The Taum Sauk collapse shows that complex automated safety systems can fail together with small construction and maintenance oversights, so redundancy alone is not enough and a simple, reliable spillway is essential.
