The really big news from the team constructing the New Irvington Tunnel – a seismically designed crucial tunnel between Sunol Valley and Fremont and our 2.6 million Bay Area customers – is that installation of the cement mortar lining has begun! Although this may seem like a good time to yawn, this is actually really exciting news! Here’s why.
It is one of the final stages of constructing a water tunnel before we bring it into service. The New Irvington Tunnel is 95% complete, and we hope to bring the new tunnel into service this fall. Now are you more excited?
First we excavated the tunnel from four different locations using road headers and drill and blast methods. Then we inserted steel pipe final liners into the 3.5 mile long tunnel. We welded the pipe together and injected grout in the space between the pipe and the tunnel to seal it off from groundwater intrusion along the entire 3.5 mile length.
There is still work left to be done before water delivery can begin, but cement mortar lining application is a key step to prevent corrosion of the steel pipe and prepare it for water conveyance. Our workers will use specialized equipment that sprays cement on the pipe’s interior and creates a very smooth surface.
Mortar Lining being applied in the New Irvington Tunnel
Installation of the mortar lining should take about two months. After that we will complete the pipeline connections on both ends of the tunnel and install rounded dishhead caps on the end of the pipe. Then SFPUC Operation crews will disinfect the entire pipe, flush it and bring it into service by the end of October 2015. Surface work and restoration will then take up the remaining months of the project. We anticipate being done in summer 2015.
So although the words “mortar lining installation” might not stop traffic, it is music to our ears!