After the flood

On December 14, 2005, Jerry Toops, his wife, and three children took a wild ride on a 20-foot wall of water down the Black River and emerged with only minor injuries. Their home, the superintendent’s office of Johnson’s Shut-Ins State Park and Taum Sauk State Park, however, was obliterated by the cascading waters.

The cause of the disaster was a breach of the upper reservoir of the Taum Sauk pumped storage plant on the peak of Proffit Mountain in eastern Missouri. This plant is notable in that it is a pure pump-back operation. Electrical generators are turned by water flowing from a reservoir on top of Proffit Mountain into a lower reservoir on the East Fork of the Black River. The generators and turbines at river level are reversible, and at night the excess electricity available on the power grid is used to pump water back to the mountaintop.

Apparently due to mechanical failure in the pump-back system, the reservoir overtopped, causing the earthen levees to erode. It was likely that the reservoir failed when water overflowed, releasing a billion gallons of water in twelve minutes into the river valley below.

After much public debate, rebuilding of the reservoir began in late 2007. This time, instead of the previous rock-fill design, the new dam is being built on bedrock and is made of roller compacted concrete (RCC). The special concrete, which contains fly ash, is drier than traditional concrete and is made on site in three plants. It is laid down in 18-inch lifts, each of which is roller compacted. Construction is expected to be completed by May 2010.