October 7, 2005

Santa Clara County plans to reduce water outages in disaster

The Santa Clara Valley Water District recently unveiled a plan to lessen impacts on the county’s water supply system during a disaster.

According to the District’s Water Infrastructure Reliability Project report, developed in coordination with water retailers and other water agencies, a magnitude 7.9 earthquake along the San Andreas Fault could damage pipes and disable pump stations and treatment plants that purify and deliver drinking water to municipal and private water companies in many areas of the county. Outages could last as long as two months.

To minimize those outages, recommendations in the report address short-term actions and longer-range capital improvements.

“Safeguarding our facilities that treat and deliver drinking water to Santa Clara County residents and businesses continues to be our top priority,” said Water District CEO Stan Williams. “Our focus now is to work with our partners to invest in long-term improvements to ensure the reliability of the water supply system when we most need it.”

In the near term, the Water District is spending $2 million to purchase and store replacement pipes and hardware. With an adequate supply of replacement pipe, the study concluded, the Water District could cut in half the time it takes to restore water service.

Long-range projects include expansion of well fields on the west and east sides of Santa Clara Valley to take advantage of the county’s groundwater basins, which would require additional investment.

Water District CEO Stan Williams

To evaluate the vulnerability of the county’s water supply infrastructure to a catastrophic event, the Water District led a two-year effort to analyze the system using complex computer models.

“The report is a good first step in the planning process to protect our water supplies against catastrophic failure from a manmade or natural disaster,” said George Belhumeur, senior vice president of operations for the San Jose Water Co.
“Our challenge now is to design, integrate and implement cost-effective and reliable improvements that meet the specific needs of each retailer’s system.”

The study looked at the implications of large earthquakes, both within Santa Clara County and to the surrounding area.

It simulated two earthquake scenarios. For a massive earthquake on the San Andreas Fault—approximately 10 times greater than the 1989 Loma Prieta earthquake—it may take as long as 30 days to restore service to nearly full capacity if replacement pipe is available.

Pipelines and pumps used to import water into the county from the Sacramento-San Joaquin Delta could be out of service for three to seven days and it may take as long as 60 days for water to be delivered from a different imported-water source.

In the second scenario, which includes a smaller magnitude earthquake on either the South Hayward Fault or Central Calaveras Fault, nearly full restoration of service is estimated within seven days.

The risks to Santa Clara County’s water delivery system from regional power outages and flooding were not as severe as earthquake events, according to the study.

The Water Infrastructure Reliability Project is the latest in a series of endeavors over the past five years to protect the county’s water supply from disasters.

When rolling blackouts in the summer of 2001 threatened to interrupt water treatment and pumping capabilities, the Water District and the county’s 11 retailers formulated contingency plans to keep tap water flowing during power outages.

In response to Sept. 11, the Water District took additional steps to protect local reservoirs and water-supply infrastructure. The district has also completed an asset management program to preserve the integrity of key county water facilities and is also in the midst of installing monitoring equipment to continually evaluate the conditions of the county’s 10 dams as part of its Dam Safety program.

Participants in the development of the report included the cities of Gilroy, Milpitas, Morgan Hill, Mountain View, San Jose, Santa Clara and Sunnyvale; California Water Service Co.; San Jose Water Co.; Great Oaks Water Co.; California Department of Water Resources; U.S. Bureau of Reclamation; Alameda County Water District; Bay Area Water Supply and Conservation Agency; City of Palo Alto; Pajaro Valley Water Management Agency; San Benito County Water District; San Francisco Public Utilities Commission, and Zone 7 Water Agency.

A summary of the report is available on the District’s Web site, www.valleywater.org.