Gravity Pipeline December 2021

SVCW’s contractor partner, Barnard-Bessac Joint Venture (BBJV), completed the downstream stage of installation of Fiber Reinforced Polymer (FRP) pipe segments in the second-drive tunnel.  This stage extends from the Surge and Flow Splitter (SFS) shaft, located at the Front-of-Plant (FoP) project site adjacent to the SVCW WWTP, to a point midway between the SFS shaft and the access shaft located at the BBJV work area at the intersection of Holly Street and Shoreway Road, near the San Carlos Airport.

FRP pipe install preparations

The FRP pipe will carry raw wastewater from the member agencies’ collection systems to the SFS shaft at the Front of Plant site. Installation of the first stage pipe was challenging due to distance from the airport access shaft, where the pipe segments are being moved into the tunnel, and the curvature of the tunnel alignment, resulting in slower pipe installation production times to allow BBJV’s operators to move pipe segments into position without damage to the pipe. BBJV maintained consistent coordination with the subcontractors and inspectors on site through the entire duration of the installation, to ensure complete quality of work and safety on site.

FRP Pipe

Following the completion of pipe installation in the tunnel, BBJV has initiated efforts in partnership with its subcontractor, to mobilize and set up equipment in the tunnel for the upcoming cellular grouting activity. The grouting operation will involve filling the annular space between the outside wall of the FRP pipe and the inner surface of the concrete segments of the completed tunnel. Cellular grout will be used for this operation, which is a type of engineered grouting material in which cement slurry is mixed with pre-formed, density-controlled foam. This helps impart fluidity to the material and keeps it lightweight, making it easier to pump long distances at much lower pressures. This in turn helps reduce the risk of excessive stress or deformation to the FRP pipe and makes the process economical.

Pipe placer for FRP pipe install


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