First Aqueduct Treated Water Bifurcation Structures and Hubbard Hill Vents Rehabilitation Sheltered Market

The Water Authority’s First Aqueduct contains six tunnels to convey water by gravity through the hilly topography. At the entrance to each tunnel, buried concrete bifurcation structures combine flows from Pipelines 1 and 2 into a single tunnel. On the downstream side of each tunnel, the bifurcation structures split the flow from the single tunnel back into Pipelines 1 and 2. Above-grade concrete vent structures are also used in parts of the aqueduct piping to allow air entry and release at system high points. This project will rehabilitate six bifurcations and two vent structures in the northern portion of the First Aqueduct that delivers treated water.

The project will use cast in place concrete to provide seismic upgrades at these structures. New, precast concrete panels will be used to seal the tops of the modified bifurcation structures. Around the inside vent structures, fiber-reinforced polymer (FRP) composite fabric and high-modulus, precured carbon anchors will be installed. At-grade concrete pads will be poured around or adjacent to the structures and new chain link fencing will be installed. Pipeline shutdowns are also scheduled to facilitate the rehabilitation work inside the structures.

Estimated Value
$2,500,000 - $3,500,000

Contact
Jim Zhou

Senior Engineer
jzhou@sdcwa.org