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 June 2021

TBM Status Update – June 14, 2021

As of June 14, 2021, Salus tunneled 12,208 feet from its launch shaft and built  2,437 rings. Tunnel production towards the Front of Plant (FoP) project site continues, as the date for TBM break-in to the receiving shaft approaches. The Surge/Flow-Splitter shaft (SFS) element of the FoP project is serving as the TBM retrieval shaft before being repurposed to be part of the FoP project.

BBJV will perform demolition of a portion of the SFS Shaft wall, limited to the specific section where Salus will be breaking through. This demolition will reduce the extent of the concrete wall that the TBM will need to mine through to break in. The demolition work follows a planned approach to ensure safety of the break-in operation. 

Once partial wall demolition work is complete, BBJV will fill the SFS shaft with soil and water to allow Salus to mine into the SFS under safe conditions, like the mining conditions Salus has encountered over the 3.5 miles of mining completed so far.  

As Salus enters the final stretch of mining, BBJV is keeping up with its daily tunnel task force and check in meetings where the real-time TBM and mining parameters are discussed in detail. 

Monthly Update: May 2021

Salus is in its last stretch of tunneling!
Barnard-Bessac Joint Venture (BBJV) has consistently monitored and maintained the tunneling equipment and parameters to ensure this drive went smoothly. With the constant check-ins and monitoring, Salus is on schedule and on target for break-in at the surge-flow splitter (SFS) shaft.
Crews continue preparing the SFS shaft and surrounding ground for Salus’ break-in. To ensure that Salus has a safe and successful break-in, BBJV will use a Roadheader (excavator-like machine) to demolish part of the SFS internal wall to a diameter slightly larger than Salus.
Around the shaft, ground improvements are complete with all jet grout columns installed, which reduce and prevent groundwater from entering the shaft during break-in. BBJV is performing strength and permeability testing ahead of break-in as part of their quality control, ensuring they meet the required parameters.

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