The Dumbarton Crossing of Bay Division Pipelines 1 and 2 (BDPL 1 & 2) crosses San Francisco Bay just south of the State Highway 84 Dumbarton Bridge. BDPL 1 is a 60-inch diameter riveted steel pipe constructed in 1925. BDPL 2 is a 66-inch diameter welded steel pipe constructed in 1936. These pipelines deliver water from Hetch Hetchy Reservoir to the Bay Area. The project limits are from the Ravenswood Valve House in Palo Alto to the Newark Valve House in Newark. The alignment at San Francisco Bay consists of a bridge section from the Palo Alto shore to the caisson and then a submarine section underneath the bay to the Newark shore. Adjacent sections are supported on timber trestles with another submarine section underneath Newark Slough. The San Francisco Public Utilities Commission (SFPUC) engaged OPAC to prepare a seismic vulnerability study, seismic retrofit recommendations, decommissioning study and maintenance plan. The directive for the seismic vulnerability study is to address the serviceability and safety of BDPL 1 & 2 for the next 15 years until a new replacement facility is built. Ground motions were selected to have a 10% probability of exceedance in 13 years, or a return period of approximately 125 years. SFPUC will likely decommission the Dumbarton Crossing after the new replacement facility is put into service.