The existing Irvington Tunnel was built in the early 20th century and can no longer be taken out of service for repairs or maintenance without impacting the water supply to customers. The New Irvington Tunnel is designed to provide a seismically-strengthened or reinforced connection between water supplies from the Alameda Watershed to Bay Area customers.
The Alameda West Portal in August of 1929. Miners excavated the existing Irvington Tunnel between 1928 and 1931 primarily using drill and blast techniques.
The Alameda West Portal in April of 2011. Miners are using road headers (conventional tunneling machines) and limited controlled detonations to excavate the tunnel. The project is expected to be completed by mid-2014.