Claremont Tunnel Seismic Upgrade
Winner of the American Society of Civil Engineers – Charles Pankow Award for Innovation
East Bay Municipal Utility District
Over the course of two years, Atkinson constructed a concrete-lined horseshoe bypass tunnel, measuring 2,000 linear feet and 16 feet in diameter, to bolster the existing tunnel where it intersects the Hayward Fault. The new tunnel incorporates an expanded vault section, which spans 100 feet across the primary fault zone and encloses an 85-foot-long, six-foot-diameter, three-inch-thick steel pipe designed to protect the water supply from debris in the event of seismic activity.
The vault is designed to compensate for up to one foot of creep over the tunnel’s design life and can endure a 7.5-foot, earthquake-induced offset. Side drifts on both sides of the tunnel were filled with lean concrete to prevent erosion to the host rock should an offset occur.
In addition to Atkinson's work on the bypass, crews also rehabilitated the existing 18,065 linear-foot tunnel, performing systematic contact grouting throughout.
Seismic upgrade of the Claremont Tunnel received the 2009 Charles Pankow Award for Innovation from the American Society of Civil Engineers (ASCE). Out of 75 projects submitted, the EBMUD Claremont Tunnel Project was recognized for its first-of-its-kind design to secure the water supply to millions of customers in the event of a major earthquake.
It is really an honor to all the EBMUD staff and consultants who had a hand in the project design and construction.
David Tsztoo, Project Manager, East Bay Municipal Utility District