Lake Oswego – Tigard Water Partnership Structures

The Lake Oswego – Tigard Water Partnership was an expansive, nine-year-long effort to create a new water supply system for the two cities. In addition to more than 10 miles of large-diameter pipeline, the project included several major structural components for which DOWL served as a specialty structural engineering consultant:

• The river intake pump station draws water directly out of the Clackamas River and is a critical piece of the water supply system. A 68-foot-long pipe bridge was then a major component of this project as it connects this off-shore structure to the shoreline. The bridge supports a 46-inch-diameter welded steel pipe and includes an innovative shear key foundation system to prevent the tower from overturning during seismic events.
• The Waluga Reservoir 2 is a new 3.5-million-gallon prestressed concrete reservoir situated in a heavily-wooded neighborhood in Lake Oswego on property adjacent to the existing four-million-gallon Waluga Reservoir.
• The Bonita Pump Station (BPS) provides an initial operating capacity of 14-million-gallons per day with the capability of expanding in the future to 20-million-gallons per day. The BPS was designed to serve the Tigard 410 Pressure Zone and may also be designed to serve both the Tigard 410 and 470 Pressure Zones through separate and parallel pumping systems and discharges.