Tunnel cross section

Seismic upgrade of the Claremont potable water supply tunnel across the Hayward Fault in the San Francisco Bay Area 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.

"I was more surprised than anyone that the project was selected for this award," said David Tsztoo, Project Manager for EBMUD. "We submitted our application for 2008, but the committee must have held onto our application for this year. It is really an honor to all the EBMUD staff and consultants who had a hand in the project design and construction."

Before and after the earthquake

Instead of building an entirely new tunnel, the design called for a 1,570ft (478m) seismically engineered bypass of the Hayward Fault crossing and upgrade of the remaining length of the existing 18,065ft (5.5km) long tunnel, built in the 1920s. For the 30m (100ft) length across the fault, the innovative bypass design features an expanded vault that is engineered to handle up to 8.5ft of quake-induced offset. As added protection, a smaller internal carrier pipe sits on sliding cradles through the fault section, allowing it to move during an earthquake and protect the supply of drinking water from falling debris. With a 130-million gallon/day capacity, the carrier pipe can maintain lifeline service to customers during any potential repair outage. Two smaller, concrete-filled tunnels on either side of the bypass will prevent water erosion of surrounding ground in the event of significant earthquake offset.

Bypass tunnel

Jacobs Associates of San Francisco lead the design team that included Camp, Dresser & McKee, Geomatrix consultants and Earthquake & Structure. According to Jacobs Associates, "the challenging project required a highly collaborative process involving staff from the East Bay Municipal Utility District, engineering consultants, and a panel of highly regarded experts from the tunneling industry and academia."

Atkinson Construction won the construction contract with a bid of $31.6 million. An AM-75 roadheader excavated the mélange deposits from the portal and the soft, potentially squeezing breccia and gouge of the fault zone. Strictly controlled drill+blast was used for the final reach into sandstones and shales along the 478m (1570ft) bypass alignment. Excavation began in late August 2004 and was completed in spring 2007.

David Tsztoo (right) on location

According to EBMUD the bypass tunnel innovation saved the utility more than $50 million; construction took far less time than a new tunnel would have; and it required only two winter season outages to connect the existing tunnel to the new fault zone section bypass.

Project Manager Tsztoo will accept the prestigious award on behalf of the project players at ASCE's Outstanding Projects and Leaders (OPAL) Gala in April in Washington, DC. The OPAL Award is the preeminent award program for civil engineers and ASCE's principal mechanism for bringing worldwide attention to the accomplishments of the US civil engineering community.

Tsztoo left EBMUD in July 2008 to accept a position at the San Francisco Public Utilities Commission (SFPUC) where he is Senior Project Manager for the New Irvington Tunnel Project, which is scheduled to be advertised for bid in October/November of this year.

Tsztoo will also serve on the Awards committee for the next two years to help decide future recipients of the award.