- Location: Madras, Oregon
- Owner: Portland General Electric Company
- Engineer(s): CH2M Hill
- Contract Type: Design-Assist (negotiated)
- Status: Completed
Continued efficient power generation and improved fish biology had to come together for PGE and the Confederated Tribes of the Warm Springs Reservation (joint owners) to receive FERC relicensing for the hydropower plant at Round Butte Dam. Barnard joined the project team at the 25 percent design stage, helping craft a workable approach within the project’s limited on-shore workspace and deep-water construction location. The massive completed structure – over 300 feet in height and weighing over 5 million pounds – had to be constructed with only a postage-stamp-sized pad on the dam’s right abutment, just enough space to operate one crane and unload materials. We built the structure on the water.
We assembled five separate large steel structures on the water, each requiring a different flotation method. To perform underwater excavation, drilling, and grouting at water depths of over 270 feet while avoiding the safety risk, time and expense of sending divers down, we focused on working via remotely operated vehicles (ROVs), brainstorming concepts more than a year in advance. Detailed advanced planning is critical when excavating 200 CY of solid rock 10 feet from an active intake without any blasting. Innovation also came to the fore in both our method of attaching the structure to an existing concrete powerhouse intake on the reservoir floor and floating a significant fish transfer facility above it. And the SWB structure was submerged, attached to the intake 270 feet below lake surface and anchored there with pipe pile using only two deep-water dives! This unique structure required extensive work by naval architects and modeling by our team to determine anticipated ballast and rate of ballasting. The results? FERC approved the license renewal for continued hydropower generation and the fish responded immediately.