Divers to repair fish ladder
March 23, 2013
Pile drivers are part of the equipment being used to bolster the base of a concrete fish ladder at the Leaburg Dam.
LEABURG: A Eugene Water & Electric Board contractor mobilized equipment in late February to begin a project to reinforce the fish ladder on the south side of Leaburg Dam on the McKenzie River. The area beneath the structure’s concrete foundation has been scoured out and eroded since it was built in the late 1960s, requiring substantial reinforcement to prevent the ladder from tipping.
To reinforce the foundation, the contractor, Portland-based Advanced American Construction, is driving steel I-beams and sheet piles into the bedrock around the foundation of the fish ladder to prevent additional erosion. Divers will follow up by placing heavy-duty, custom-made bags under the foundation. Once the giant bags are in place, workers will pump each bag full of concrete to fill the void beneath the fish ladder foundation.
EWEB engineer Steve Celeste estimates the void under the fish ladder foundation amounts to approximately 60 cubic yards.
“Once the bags are in place, divers will connect a nozzle to a concrete pumper hose and then fill each of the bags,” Celeste said. “It will be quite an operation.”
Celeste said EWEB decided to go with the concrete bags to avoid spilling any wet concrete into the river.
Advanced American Construction started driving H-pile and sheet pile around the lower fish ladder on March 11th. Placement of the pilings should be complete by March 22nd. Divers will then use torches to cut the steel piles to a depth below the ordinary low-water mark.
Celeste expects crews working underwater will begin filling the bags with concrete around March 25th. All in-water work, including smoothing the rough edges of the steel piling with a grinder to minimize injury to fish, is scheduled for completion by April 15th.
Advanced American Construction was the low bidder on the contract, coming in at $499,150. The engineering estimate was $500,000.
McKenzie River Reflections