Dallas Lock and Dam Auxiliary Water Supply Trash Rack Cleaning System

The U.S. Army Corps of Engineer (USACE) Portland District (NWP) intends to solicit construction firms who are interested in submitting a competitive firm-fixed-price bid for this project. This PRESOLICITATION notice for the The Dallas Lock and Dam (TDA) Auxiliary Water Supply Backup Debris Management. Project Background. The Dalles Lock & Dam is 192 miles from the mouth of the Columbia River near the city of The Dalles, Oregon. The dam is a concrete gravity and embankment structure that was constructed by U.S. Army Corps of Engineers (operationally administered by the Portland District) in the 1950s for the purposes of hydroelectric power generation and maintenance of a navigational pool (Lake Celilo). The construction of the dam also included northern and eastern fish ladders for the passage of fish within the Columbia basin to upstream spawning grounds. The East Fish Ladder (EFL) is the primary and most heavily used of the two systems; likely because of its location within the historical riverbed and the attraction flows produced by the powerhouse. The EFL is a pool and weir ladder located at the eastern extension of the powerhouse providing passage for Salmon, Steelhead, and several listed species of the Endangered Species Act (ESA). A key aspect of the ladder functionality is the attraction flow at the inlet; which in the case of the EFL is normally provided by attraction flow units (approx. 5,000 cfs, ea.). An Auxiliary Water Supply Backup (AWSB) System was completed in 2020 that addressed risk profiles that had been studied since 2008 to provide an alternative source of attraction flow in the event that the turbine units failed (original to construction of the project). The AWSB is an auxiliary water source for the east, west, and south entrances of the EFL, consisting of a forebay inlet structures w/ protective trashracks, 10-ft diameter penstock through the eastern non-overflow concrete dam, 120-inch isolation and emergency shutoff valve, bifurcation to 7-ft diameter conduits, 84-Inch diameter on/off control valves, and interconnection with the attraction flow system. The AWSB intake is protected by trashracks (stiff steel “screens”) that are installed into a slot within the forebay intake structure that was added as part of the AWSB system in 2020. The inlet trashrack is comprised of 11 identical six-foot tall by 24-foot-wide panels which can be stacked in any order to isolate the intake from debris and fish using screening W15-W-2, 1-1/4” x 3/16” steel bar grating secured to the steel frame of the trashrack. Project Scope. This project is a Design-Bid-Build construction requirement which will provide a predesigned mechanical method for dislodging debris from the trashracks at the EFL AWSB system intake. This will remove the need for operations staff to shut down the AWSB system to let river currents clear accumulated debris from the screens. The predesigned AWSB Intake trashrack cleaning system is based on a telescoping boom mounted rotating bristle brush and includes the following: Pavement repairs and trenching required for power and controls will utilize standard ODOT details. The mechanical equipment associated with the rotating brush (also referred to as the trashrake) will be supplied from an equipment product line developed for cleaning similar style intakes. The equipment will be mounted on the upstream forebay structure and accessed from a fixed access platform with a transition to a traveling trolley platform. The equipment supplier will coordinate the details of the equipment and mounting systems with the Installation Contractor. Structures to be included in the project are fixed upper and lower operator/mechanic platforms which will project from the AWSB intake deck and are accessed by a series of ladders for operational and maintenance needs of the mechanical systems and brush head. The platforms will be fabricated from structural steel and anchored to the vertical concrete wall of the intake with post-installed epoxy anchor rods. Electrical power supplied will be fed from MCC FCQ7 in the service gallery of the eastern non overflow dam, which has sufficient capacity for the loads stated in the DDR. Power and data conduits will be routed from the service gallery around the dam monoliths to the eastern embankment, where the conduits will cross the access road with a shallow trench and be face mounted to the upstream parapet wall to the AWSB intake. The control of the equipment will be from the vendor supplied control system using operated initiated cycles. The status of the machinery and AWSB intake differential water levels will be sent to the East Exit Fish SCADA PLC where the equipment status and differential alarm data will be monitored by the plant SCADA system. Anticipated Construction Schedule: CENWP intends to advertise in late June/early July 2026 and award in September 2026. Construction Contract with estimated construction completion by the en