McMillen Jacobs Associates (McMillen Jacobs) constructed lamprey passage improvements in the adult fishways at Ice Harbor and Lower Monumental Lock and Dam. The improvements included installation of lamprey orifices at the base of concrete weir walls in the fishway control sections, fabrication of stainless steel components such as lamprey orifice inserts, fish orifice invert plating at floor diffusers, lamprey ramps at both existing fish orifices and new lamprey orifices, and the construction of both stainless steel and concrete ramps at existing fish orifices.
The project required cofferdam installation and bypass pumping in the fish ladders during construction. In water, work windows were constrained and required careful coordination for the project.
A major concern for the USACE was the finish on the bottom cut of the new lamprey orifices. Prior contractors required large amounts of epoxy installation to smooth out the concrete demolition for a smooth lamprey surface. McMillen Jacobs was able to work with their concrete cutting subcontractor and approach the removal in a different way that allowed for minimal to no epoxy use on the bottom of the orifices. The project had a four-week duration and was completed one week ahead of the required completion period.