Submitted by CH2M HILL

This $108-million project reestablishes steelhead and salmon passage around a hydroelectric dam near Madras, Ore., for the first time in 40 years. After two years of design for a site where there was almost no room for construction, engineers came up with the selective water withdrawal facility, which is the only floating surface fish collection facility connected with a hydroelectric power generation intake system in the world. The project also improves downstream water quality by regulating water temperature.

Photo: CH2M Hill/Dix Corp.
Photo: CH2M Hill/Dix Corp.

The facility stands 273 ft tall, nearly as tall as the Statue of Liberty, with all but the top 5 ft of the structure submerged in the waters of Lake Billy Chinook. The 13,500-sq-ft intake structure weighs 5 million pounds and floats gently on the surface of the lake with the help of 32 concrete floats.

All the major components were constructed on the water using various techniques for floating the structures during erection. Each component was then moved into position and secured to complete the final structure.

The “fishtight” structure allows no gaps of more than 1/4 in. on any of the walls or joints. To achieve this level of structural fit, subassemblies were shop-fabricated and shipped in large pieces, up to 20 ft wide and over 70 ft long.

Owner: Portland General Electric
General Contractor: Barnard Construction Co. Inc.
Engineer: CH2M HILL
Subcontractor: Dix Corp.