Crews have finished excavating the downstream portion of Chimney Hollow Reservoir’s inlet/outlet tunnel and are now installing the concrete liner. In mid-June, crews began installing the first reinforced concrete section with an Everest Carrier Form, which is 67 feet long and weighs approximately 183,000 pounds.  

“This machine has ports inside the form that shoot out, connect into a fitting, and place concrete along the tunnel’s structure,” said Kyle Knaeble, a project engineer with Barnard Construction. 

For the placement, crews use a self-consolidated concrete to avoid using built-in vibrators, which makes it much easier to place the concrete and maintain quality.

The downstream liner is expected to be complete in March 2024 while crews continue excavating the upstream portion. Within a year, the tunnel’s excavation and ground support will be complete.