For the past 20 years, Tetra Tech has helped maintain and improve the Bonneville Lock and Dam, a National Historic Landmark that was completed in 1938 as a Public Works Administration project as part of the New Deal.

Tetra Tech has provided a wide variety of structural, mechanical, electrical, civil, and fisheries engineering services at Bonneville Dam for the U.S. Army Corps of Engineers. Other services provided include preliminary and final design, inspection services, and cost estimating.

Recent projects completed at Bonneville Dam include:

• Plans and specifications for modifying the Cascades Island Fish ladder to allow lampreys to cross the dam without compromising the salmon passage
• Plans, specifications, and cost estimating services for lock control system replacement
• Electrical, structural, and mechanical engineering and cost estimating services for spillway gate full-flow hoists, replacing the unsafe process of removing hoist and gate by gantry crane with vertical lift gates that can be taken out of the flow during floods
• Design services for rehabilitating aging spillway gate hoists to improve the life of the hoists for another 20 years
• Inspection and engineering services for the replacement and refurbishment of an 85-ton-capacity gantry crane
• Design engineering report for wastewater improvements, including recommendations for treatment upgrades and strategies to manage domestic and fish hatchery sludge; also preparation of the Request for Proposal for upgrades to the plant
• Development of the facilities plan for the wastewater treatment plant, including innovative and cost-saving approach to equipment redundancy requirements for oxidation ditch and clarifier using plant’s existing aerobic digester as a standby aeration basin or clarifier