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 April 2021

TBM Status Update – April 5, 2021

Salus continues tunneling at a steady rate towards the SVCW wastewater treatment plant. As of Monday, April 19, 2021, Salus tunneled 10,267 feet from its launch shaft and built 2,048 rings.

Part of the preparations for Salus’ break in at the front of plant, BBJV is working on ground improvement around the break in shaft by installing jet grout columns. Jet grout columns are created by using high velocity fluid jets to mix cement and water with the soil in the ground. Ground improvement will allow BBJV to manage the groundwater surrounding the TBM receiving shaft when Salus breaks into the receiving shaft., making for a safe completion of the second tunneling drive.

Monthly Update: April 2021

Salus, the Tunnel Boring Machine (TBM), just entered its last stretch of tunneling while SVCW’s contractor partner, Barnard-Bessac Joint Venture (BBJV), prepares for its breakthrough at the Surge-Flow Splitter (SFS) shaft at the Front of Plant project site.  
 
The SFS shaft will receive the TBM at the end of her drive and will then be re-used for wastewater flow management once the Receiving Lift Station (RLS) and tunnel are complete. To prepare for Salus’s breakthrough, BBJV is installing jet grout columns – to prevent groundwater entering – and demolishing part of the receiving shaft’s wall at the point where Salus will pass through to the receiving shaft.
 
At the San Carlos Pump Station site, special excavation equipment was used to remove soil from the interior of the recently completed San Carlos Shaft. Air ventilation ducts were installed to provide a well-ventilated space for the workers to perform any work within the shaft.

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