Project–At–A–Glance

WSIP Region
Bay Division

Location
Fremont

Construction Start
March, 2012

Construction Finish
June, 2014

Current Status
Planning, Design, Environmental

Project Cost
$67M

The project would provide a seismically reliable pipeline crossing of the Hayward Fault in response to the Seismic level of service goals.

Bay Division Pipeline (BDPL) Nos. 3 and 4 cross the Hayward Fault near the intersection of Mission Blvd and Interstate 680 (I-680) in Fremont. In fact, one of the traces of the fault intersects the pipelines under I-680. It is very likely that an earthquake on the Hayward Fault would rupture one or both of these pipelines.  

In the recent BDPL Nos. 3 & 4 Crossover / Isolation Valves project, the SFPUC installed crossover/isolation valve vaults on the pipelines on either side of the Hayward Fault, which allows SFPUC to isolate a pipeline rupture due to an earthquake.  This project would seismically upgrade the pipeline between the two vaults. 

Description
The existing pipeline fault crossing between the two crossover/isolation valve vaults  is about 2,400 feet in length, and consists of BDPL No. 3, a 78-inch-diameter reinforced concrete cylinder pipe, and BDPL No. 4, a 96-inch-diameter pre-stressed concrete cylinder pipe.  The vaults are located east and west of I-680 near the intersection of Mission Boulevard.  At this time, the project scope would include a seismic upgrade of BDPL No. 3 as only one pipe is required to meet the seismic level of service goals.  However, if further analysis determines that the upgraded BDPL No. 3 would not accomodate leakage from a possible rupture of BDPL No. 4 after an earthquake, the project scope will need to be revisited.  The planning-level project scope would include replacement of about 2,400 feet of BDPL No. 3; however, a detailed assessment of actual pipe replacement requirements is underway, and may determine that more or less length of new pipe would be required.  It is planned that about 350 feet of the new pipeline would cross under I-680 in an existing casing pipe, about 300 feet that crosses Mission Boulevard would be in a newly constructed concrete vault (“box culvert”), and the remaining new pipeline would be buried.  All new construction would be in the SFPUC’s existing right-of-way.

The project would primarily consist of:

• A new 300-foot-long concrete vault constructed under Mission Boulevard near the I-680 Interchange where the main fault trace is located. A new 300-foot segment of 72-inch diameter, welded steel BDPL No. 3 would be installed inside the vault. Within the vault, and on either side of the fault trace, 72-inch diameter ball joints and slip joints would be installed that will accommodate the fault displacement during a seismic event.  Further planning is required to optimize the size of pipe and ball joint diameters.
• For the crossing under I-680, about 350 feet of 78-inch-diameter welded steel pipe would be installed in an existing, unused casing pipe.
• About 1,750 feet (may be increased or decreased based on upcoming detailed assessment) of new 78-inch diameter buried welded steel pipe would connect the existing and new segments between the two vaults.

Note: Schedule and cost information shown may vary from the 2007 Approved WSIP Schedule and Budget. The information shown reflects the current forecast information published in the latest WSIP Quarterly Report.