Dome Technology has produced a video documenting an outlet-pipe rehabilitation project completed at Hebgen Dam in Montana in 2017.
Completed in 1911, the original unreinforced concrete pipe lined with 16-foot-long (4.88m) wood-timber staves functioned as the reservoir’s low-level outlet for more than 100 years.
Dome Technology was contracted to rehabilitate the 475-foot (145m) tunnel for another century of function by installing a concrete liner inside the pipe. The team started by removing the wood staves, then used chemical grout injections to stop leaks in the existing pipe. Next, the team lined the bottom of the tunnel with prebuilt rebar cages. Concrete was then placed and finished on the lower portion of the tunnel. Crews did the same for the top portion of the tunnel, applying concrete to the upper curve using the shotcrete method. In fact, “it was our ability to position the rebar and spray the concrete that made us valuable on this project,” said Dome Technology project manager Jason Craig.