Friday, February 28, 2014

Lined, Then Sealed, Then Delivered This Fall. The New Irvington Tunnel Reaches Another Milestone

Imagine an 8.5 foot in diameter steel pipe roughly the length of a tractor trailer. Now imagine gently placing it into a 14-foot tube the length of 1½ Golden Gate Bridges? Now weld each of them together from the inside of the installed pipe in less than two months.

Well, that is EXACTLY what we did. This week the New Irvington Tunnel contractor completed the installation of a total of 14,600 feet (2.7 miles) of the welded steel liner into the tunnel. The 50 foot segments were all installed from the Sunol Valley and transported with a customized pipe placer westward into the tunnel. This completes the steel lining for the entire 18,660 foot (3.5 miles) New Irvington Tunnel.

What’s next? More grouting! Our teams will mobilize in March to prepare the tunnel to place cellular grout into the space between the steel liner and the excavated tunnel. This will effectively backfill the space between the tunnel pipe and tunnel wall, sealing it off to prevent water from seeping into or out of the tunnel.

We plan to bring the New Irvington Tunnel into service this fall, when drinking water will officially be transmitted through the new tunnel. Final project completion of the New Irvington Tunnel Project – including above ground restoration - is expected in mid-2015.

The New Irvington Tunnel will provide a seismically designed connection for water supply for 2.6 million bay area customers. 

50 ft segments of steel liner being delivered
Photo credit: Robin Scheswohl

View of steel liner from inside of Alameda West Portal
Photo credit: Robin Scheswohl

Welding work taking place on steel liners
Photo credit: Robin Scheswohl

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