What is the Gravity Pipeline Project?

The Gravity Pipeline (GP) Project consists of the design, construction, permitting, start-up, commissioning, and closeout of approximately 17,600 feet of wastewater gravity FRP pipe inside a concrete-segment tunnel. The work includs three shafts and will interface directly with the Front of Plant (FoP) Project at the Receiving Lift Station (RLS). Work is being implemented under a Progressive Design-Build procurement process.

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Gravity Pipeline Project

Last Updated November 2020

TBM Status Update – November 30, 2020

Salus continues to tunnel without interruptions. There have been 762 rings built and the TBM mined 3,838 feet since leaving its launch shaft at Holly Street and Shoreway Road. We expect to conduct several short-term stoppages to check on the cutter wheel’s condition on the face of the TBM. Barnard-Bessac Joint Venture (BBJV) continue to record daily data from the settlement monitoring points; data reflects conditions that are within acceptable limits.

TBM November Monthly Update

Salus, the Tunnel Boring Machine (TBM), is on its second drive of mining, making its way towards the wastewater treatment plant. So far Salus has mined over mined 2,440 feet and installed 482 rings within the tunnel. Contractor partner BBJV constantly checks for potential ground settlement and production status via an online monitoring portal.

While Salus mines towards the treatment plant, BBJV is installing the Fiberglass Reinforced Plastic (FRP) pipe segments in the section of the tunnel completed between the launch shaft and Inner Bair Island. These pipe segments will form the carrier pipe that will eventually carry raw wastewater to the SVCW treatment plant by gravity.

At the San Carlos Pump Station site, BBJV is installing 69-foot excavation support structure, known as secant piles, which overlap with adjacent piles to form a ring that will allow soil to be excavation by the ring. This creates a vertical shaft that stabilizes the surrounding soil and prevents the entry of groundwater. BBJV will use this vertical shaft to build the connecting structure that will allow raw wastewater flows from the Cities of San Carlos and Belmont to enter the gravity pipeline that will carry flows to SVCW’s wastewater treatment plant

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Gravity Pipeline Project

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