Heavy Civil Mechanical

The scope of work includ­ed the instal­la­tion of new self-clean­ing fish screens and a per­ma­nent bypass at the entrance to an exist­ing 11-mile long pow­er tun­nel, to pro­tect and enhance fish, wildlife, water qual­i­ty, recre­ation, and cul­tur­al resources. The bypass reg­u­lates instream releas­es for con­vey­ing fish, debris, and sed­i­ment from the intake to the receiv­ing tail­wa­ter pool. The project also includ­ed con­struct­ing a con­trol build­ing for hous­ing electrical/​control equip­ment nec­es­sary to mon­i­tor, auto­mate, and main­tain the fish screened intake.

The Project posed a num­ber of unique chal­lenges, includ­ing: work with­in the riv­er; instal­la­tion of a water-filled blad­der cof­fer­dam sys­tem; dewa­ter­ing and bypass pump­ing around the project site; earth­work, grad­ing, and place­ment of con­crete struc­tures down­stream of the cof­fer­dam; start­up of mechan­i­cal pumps and pip­ing; and facil­i­ty test­ing and start­up. In addi­tion, the iso­lat­ed loca­tion and tor­tu­ous dirt access road down to the Project neces­si­tat­ed onsite batch­ing of con­crete and pro­cess­ing of exca­vat­ed mate­r­i­al for reuse as backfill.