The 100-year-old Lost Creek Dam was repaired using a novel method: hydrodemolition. Midwest Mobile Waterjet, Minnesota-based hydrodemolition contractor, traveled all the way to northern California to remove unsound concrete from this 120-foot-tall structure. The design specifications required the contractor to remove all unsound concrete from the dam face and leave only concrete that was a minimum of 1,500 psi compressive strength. After the concrete was removed, the next phase was to drill and dowel horizontal rebar and pour a new facing. The three-month-long project was finished on July 21, 2015. Four Midwest Mobile Waterjet employees and four climbers removed a 13,000 cubic feet of concrete using robotic hydrodemolition equipment specifically designed for vertical surfaces.

AECOM engineers decided that hydrodemolition was the best method for removing concrete from the dam face. Robotic hydrodemolition was chosen because it can remove the bad concrete while leaving good concrete, and it does not induce vibration that could cause the dam to fail.

Shawn Hayse, special project manager for South Feather Water & Power Agency, realized that hydrodemolition was the best option for this project.

“Hydrodemolition gave us the opportunity to preform work without compromising structure,” says Hayse.