Gravity Pipeline April 2022

Following installation of the fiberglass reinforced polymer (FRP) pipe inside the gravity tunnel, SVCW’s contractor partner for the Gravity Pipeline project, Barnard Bessac Joint Venture (BBJV), has completed cellular grouting work in the tunnel, filling the annular space between the pipe surface and the inner wall of the tunnel. BBJV is completing inspection walks in the tunnel to view the finished pipe installation in the tunnel. This activity will be followed by installation of the last set of tie-in pipes inside the Airport Access Shaft, which was the TBM launch shaft. The installation of the tie-in pipes, which will connect Tunnel Drive 1 to Tunnel Drive 2, will complete the construction of the conveyance portion of the Gravity Tunnel Project. BBJV continues to maintain consistent coordination with its subcontractors and inspectors on each site, to ensure crew safety.

At the Bair Island shaft, installation of the Bair Island Drop Structure continues. BBJV has completed the removal of sheet piles that formed the Bair Island Shaft following completion of backfill of the Bair Island Shaft. BBJV continues the installation of the Bair Island inlet structures, which control the flow of raw wastewater into the gravity tunnel. Current activities include installation of the vortex drop structure and access entry for future placement of maintenance equipment in the gravity tunnel, if needed.

Bair Island Shaft vortex drop structure and equipment access entry

Concurrently, construction work at the San Carlos Pump Station (SCPS) site has also begun. BBJV has completed demolition of a limited section of the existing vertical shaft walls that protect the new drop structure that connects Belmont and San Carlos collection systems to the gravity tunnel. The work on the shaft wall section provides an opening for new piping to carry collection system flows into the new drop structure, and on to the gravity tunnel.  Part of this work involves creating an opening into the existing SCPS wall to allow for the connection of new piping from the collection systems, which will pass through the SCPS structure, to the new drop structure.

Work on San Carlos Pump Station shaft wall
Work on San Carlos Pump Station shaft wall
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