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There's some commotion along the Gavins Point dam, but under the surface of the frigid water is the largest assessment and repair project in the dam's history.
"We think they were very well built. The Corps of Engineers has a really good, well-founded reputation for building good structures and these have held up well for 55 years. But you don't know for sure how well something is going to do," Gavins Point Project Operations Manager Dave Becker said.
That's why a crew that includes divers is working at the dam. They're going into the water to inspect the concrete slab that runs below the river channel. They're also drilling 40 holes in the concrete to test the gravel base below it.
The work isn't only needed because of the dam's age, but also because of the flooding of 2011. Before crews can do much more, they have to remove an estimated 8 million pounds of sediment and other debris from the submerged concrete surface.
"More than anything, we're really pleased with how the spillway held up through the flood of 2011. It had very high flows going on for two-and-a-half to three months and it held up very well," Becker said.
The debris removal work should finish up by the end of next month, clearing the way for any other repair work that may be needed. Gavins Point isn't alone. The six Missouri River dams are all subject to some work because of 2011's flooding. The work may be difficult, but the Corps says it is worth it to ensure a solid future of the man-made structures.
"They take a fair amount of maintenance. They're like anything else, you have to keep up on the maintenance if you want them to continue to last," Becker said.
The divers work in the water for several hours at a time. The Corps says the public is welcome to come out and watch.