RESCU PROGRAM: Gravity Pipeline Project

TBM Status Update – July 2021

Another Month of Good News! Salus, the mighty tunnel boring machine (TBM), has successfully completed its second tunneling drive and has tunneled into the receiving shaft located at the Front of Plant. Even more good news, having tunneled approximately 13,000 feet from its launch shaft at the intersection of Shoreway Road and Holly Street, Salus has once again reached its destination on time and on target at Silicon Valley Clean Water (SVCW)’s Wastewater Treatment Plant. This is the second major milestone for the Gravity Pipeline project team since Salus’ first break in on Bair Island that happened at the end of March 2020.  Congratulations to the tunneling team and everyone who participated in supporting the effort!

To prepare for the break in, SVCW’s contractor partner, Barnard-Bessac Joint Venture (BBJV), prepared the receiving shaft wall by using road header equipment to perform a partial demolition of the wall, limited to the specific section where Salus would be entering the shaft. The demolition work reduced the extent of the concrete wall that the Salus needed to mine through during the break in to the shaft, while still ensuring the integrity and strength of the shaft wall is maintained.

For a safe break into the shaft, BBJV had backfilled the shaft with a mix of water and soil to mimic the underground conditions that Salus had been used to tunneling through. With the breakthrough step completed, BBJV will be excavating the soil from around Salus to allow the start of the process of removing Salus, section by section, together with its supporting equipment (referenced as gantries) from the tunnel and shaft.

Upon removal of Salus from the shaft, BBJV will be installing 11-foot diameter Fiberglass Reinforced Plastic (FRP) pipe sections within the completed tunnel. These pipe segments will be installed and assembled within the completed tunnel to form the carrier pipe that will carry raw wastewater to SVCW’s treatment plant by gravity.

Having to work through COVID-19 from the end of the first tunneling drive through the second tunneling drive SVCW and BBJV have done a great job in keeping up with all health and safety measures and protocols while adjusting work procedures to ensure that tunneling production was safe and on schedule.

Again, another big CONGRATULATIONS to SVCW and RESCU’s Gravity Pipeline project team!