#4. Rocky Reach juvenile fish bypass installation — forebay pile

Original contract amount: $39,825,000

An underwater view of a portion of the surface collector.
Photo courtesy Chelan County PUD No. 1

Project address:
Rocky Reach Hydroelectric Facility, River Mile 473.7 of the Columbia River in Chelan County

Start of construction:
Sept. 1, 2002

Expected completion date:
March 31, 2003

Owner:
Chelan County PUD No. 1


Description
Rocky Reach Dam was constructed in 1956, at a time when preservation of steelhead and salmon runs was not as high a priority as ensuring a steady supply of cheap hydroelectric power.

Every year, up to 6 percent of the salmon and steelhead runs perish in the turbines in their seasonal migration to the sea.

To deal with this conservation challenge, the district was faced with a choice: Either spill 40 to 50 percent of the water by the dam, at a cost of reducing power generation by $25 million a year; or construct a pipe around the turbines through which fish could pass through unharmed.

The fish bypass was determined to be the most cost-effective solution to this environmental problem. The project has two parts. First, the fish are collected in the forebay, or upstream side of the dam. The second part involves transporting fish through a 4,600-foot bypass conduit to a discharge point in the tailrace, or downstream side of the dam.

Traylor Pacific is constructing the forebay fish collection system. This work involves many technical challenges, since much of the work is under water.

Existing surface collectors and intake screens were demolished, and several thousand tons of steel and concrete structures are being placed below the river. Pilings were drilled into the bedrock below the Columbia River, and a gigantic steel lattice with a concrete base weighing more than 5 million pounds was lowered into place last November.

Very large pumps will create water flows of up to 7,000 cubic feet per second, attracting the fish into the conduit.

The juvenile fish run is anticipated to begin next spring, and the entire project will be in place by then to accommodate migrating fish.

PROJECT PARTICIPANTS

Contractor:
Traylor Pacific, 34 Executive Park, Suite 100, Irvine, CA 92614, (949) 475-0444

Architect:
HNTB Architecture, 600 108th Ave. N.E., Suite 400, Bellevue, WA 98004, (425) 455-3555

Engineers:
CH2M Hill
EE&S Consulting
Erlandsen (surveying)
Gerwick

Other Participants
Allied Steel Fabrication
AMEC Dynamic Structures
Brooklyn Iron Works
Concrete Coring Co.
Farwest Iron Works
Harbor Offshore
Oregon Electrical Group
Selway Corp.
Steel Fab
Triad Mechanical


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