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Seismic Upgrade of BDPL Nos. 3 & 4 at Hayward Fault cross the intersection of Mission Boulevard and Interstate 680 (I-680) in Fremont. The pipelines cross three traces of the fault in this area, and it is very likely that an earthquake on the Hayward Fault would rupture one or both of these pipelines. To avoid major damage to this essential part of the Bay Area’s water-delivery system, this project replaced the existing BDPL No. 3 with a new pipeline between two recently installed vaults on either side of the Hayward Fault. The new pipeline is highly reliable in the event of a major earthquake. In addition, the existing BDPL No. 4 has been seismically retrofitted at the three fault traces. All construction activities have been completed and took place in the SFPUC’s existing right of way and in staging areas as indicated on the map at the bottom of this page. The project consisted of the following:
BDPL No. 3 Improvements
- A new 300-foot-long concrete vault will be constructed under Mission Boulevard near the I-680 interchange. Installation of a new 300-foot segment of 72-inch-diameter, welded-steel pipeline in vault. New 72-inch-diameter ball joints and slip joints.
- About 400 feet of 78-inch-diameter welded-steel pipe will be installed in an existing, unused casing pipe at the crossing under I-680.
- About 1,450 feet of new, 78-inch-diameter welded-steel pipe will connect the existing and new pipe segments between the two vaults.
- The existing BDPL No. 3 will be abandoned in place, but modifications will be made to it to collect and divert water from the area and prevent the undermining of the new BDPL No. 3.
BDPL No. 4 Improvements
- At Hayward Fault Trace C, about 400 feet of BDPL No. 4 will be replaced with new steel pipe.
- BDPL No. 4 will be encased with concrete outside the existing slip-joint vault at Hayward Fault Trace B.
- At Hayward Fault Trace A, about 300 feet of BDPL No. 4 will be slip-lined with a new steel pipe, and an expansion joint will be installed in a new vault south of I-680.
- Modifications to the existing slip-joint vault will be made, including enlarging BDPL No. 4 pipe penetrations in the vault and adding new drainage systems and new roof panels.