Contracts awarded for seismic upgrade of regional water pipelines at vulnerable Hayward Fault crossing

SAN FRANCISCO, CALIF. — San Francisco Public Utilities Commission awarded a $31.3 million construction contract to Steve P. Rados, Inc. to begin work on the most innovative and technically challenging projects of the Water System Improvement Program (WSIP), which involves a seismically engineered crossing of the Hayward Fault near the Mission Blvd/I-680 Interchange in Fremont. The professional service firm, EPC Consultants, was also awarded an $8.5 million contract to assist the SFPUC in the construction management of this project.

The Seismic Upgrade of Bay Division Pipelines (BDPL) 3 and 4 project specifically addresses one of the system’s most seismically vulnerable areas. The project will include construction of a new 300-foot-long articulated concrete vault at one fault trace, a new 2,200-foot segment of BDPL 3 pipeline across the fault zone, and the use of one-of-a-kind piping components to accommodate the compression and rotation forces on the pipeline during a large earthquake.

“When designing this project, our studies revealed that the fault could produce a horizontal displacement of 6 feet. The existing pipes would not be able to handle that much movement,” said WSIP Director Julie Labonte. “We really had to think creatively to find an engineering solution that would allow continued water delivery across the fault.”

Our engineering team of city staff and URS consulting engineers designed a unique system that includes never-before manufactured, 72-inch-diameter ball joints plus slip joint, and articulated concrete vault to accommodate the planned displacement. The new articulated concrete vault has been extensively tested at Cornell University. The new crossing is designed to withstand the Maximum Credible Earthquake on the Hayward Fault.

Construction is anticipated to begin in August 2012. This is the last of the large projects to be awarded for the $4.6 billion Hetch Hetchy Regional Water System infrastructure upgrades. The WSIP includes more than 80 projects spanning seven counties from the Central Valley to Downtown San Francisco of which 74 projects are either in construction or completed.

More information can be found online at www.sfwater.org/wsip.