Oklahoma City’s water supply depends on the Canton Lake Reservoir, a 383,000 acre-ft lake on the North Canadian River about 70 miles northwest of downtown. But in case of a thousand-year flood event, the dam needed a failsafe. That’s where Dolese and Kiewit came in.
A “thousand-year flood” doesn’t mean a flood that’s a thousand years away. It refers to the likelihood of an extreme flood event in any given year. Though a flood of this magnitude is unlikely, it is possible, and the U.S. Army Corps of Engineers demands that it be prepared for.
What this meant for the Canton Lake Dam was a massive new auxiliary spillway at the lake’s southwest end – near the existing spillway. This reroutes the water in the event of an extreme flood event so that it is held in by a failsafe dam. This dam is designed to topple over and release water if the level ever rose above the current floodgate height.
The new spillway required unfathomable amounts of aggregate, including hundreds of thousands of tons of rip-rap. Every stone had to meet the U.S. Army Corps of Engineers’ specs – which was a challenge in and of itself.
"It's how we've done it for more than a hundred years. And how we intend to do it for a hundred more."