EBMUD's Southern Loop Pipeline
In addition to questions of drinking water supply and quality, Bay Area water agencies are very aware that natural disasters such as earthquakes are a potential threat to the miles of pipelines between local reservoirs or treatment plants and customers' taps.
The East Bay Municipal Utility District confronted this problem following the Loma Prieta earthquake in 1989. The District's service area includes 20 cities and 15 unincorporated communities in Alameda and Contra Costa Counties, lying both east and west of the East Bay Hills. Active earthquake faults, including the Hayward, Calaveras and Concord Faults, cross through or close to the service area. Pipelines and tunnels serving the West of Hills area could be seriously disrupted by earthquakes on any of these faults; the most significant problem is posed by a potential 7.0 magnitude tremor on the Hayward fault.
The District's Seismic Improvement Program (SIP) was adopted in 1996, and includes upgrades to more than 400 facilities over a ten-year span. These include reservoir upgrades, a retrofit of the Claremont Tunnel which carries water from the east side to the west side of the hills, building upgrades, and improvements for pumping plants and water treatment plants.
Southern Loop
A cornerstone of the SIP is the Southern Loop Pipeline Project, which would link the southern ends of the District's pipeline system between San Ramon in the east and Castro Valley in the west. The Southern Loop would add flexibility to water supply paths following a major earthquake. In a magnitude 7.0 earthquake on the Hayward fault, the Claremont Tunnel could sustain moderate to severe damage. If water cannot pass through the tunnel, or downstream pipes and pumps are impaired, the only source for customers west of the hills would be the Sobrante and Upper San Leandro Treatment plants in the northern part of the District's service area. This service would be limited, and service to the southern portion of the West of Hills area might not be possible.
The Southern Loop would carry water from the San Ramon Valley, starting at the San Ramon Valley Boulevard/Deerwood Road intersection, to a pipeline, near the Norbridge Avenue/Castro Valley Boulevard intersection, which feeds into the Bay View Pumping plant in Castro Valley. Under the proposed design, water would flow by gravity from east to west. In emergencies, the pipeline would deliver up to 30 million gallons per day from San Ramon to Castro Valley. If an earthquake on the Calaveras fault disrupts service to San Ramon, the pipeline could be augmented by portable pumping equipment to allow a reverse flow of 5-7 million gallons per day.
Impacts
Construction will take place primarily in existing road rights-of-way, most of it along Crow Canyon Road, but at the highest point of the ridge a tunnel, approximately half a mile long, will be needed. Because construction will be done mainly in open trenches along roadway alignments, it will disrupt both local traffic and the significant regional traffic carried by Crow Canyon Road.
Residents along part of the alignment may see construction from both the Southern Loop and the Livermore-Amador Valley Water Management Agency's proposed Export Facilities Project. That project will increase wastewater disposal capacity by expanding wastewater disposal facilities, including construction of a new 16-mile pipeline from Dublin to San Leandro. Project managers for the District and the water management agency are attempting to determine whether the proposed alignments through Castro Valley might allow the two agencies to co-locate their pipelines.
Most of the Southern Loop pipeline will be outside the District's current service area but within the Ultimate Service Boundary, which determines the area which can reasonably be served with the District's available water supply. No connections will be allowed in areas where the pipeline passes outside the Ultimate Service Boundary.
The Draft Environmental Impact Report for the Southern Loop Pipeline Project will be available from the District in November. It will present alternative alignments, mitigation options, and other more detailed information on this critical water supply protection project. The District has also recently issued the 1998 progress report on the Seismic Improvement Program. Residents who have strapped water heaters to walls and stored emergency supplies may want to check up on how the District is taking similar precautions.
Leslie Stewart
For more information:
EBMUD: 510-287-0145 or online at http://www.ebmud.com.