The San Francisco Public Utilities Commission completed a $278 million seismic upgrade of the Harry Tracy Water Treatment Plant in San Bruno earlier this month, according to officials with the SFPUC.
The upgrade will allow the plant to withstand a magnitude 7.9 earthquake on the San Andreas Fault. The aim of the project is to maintain the ability to provide SFPUC customers with water within 24 hours of a major earthquake, SFPUC spokeswoman Betsy Rhodes said.
Director of the Water System Improvement Program Daniel Wade said in a statement:
“The goal of the project is to provide 140 million gallons of water per day, for 60 days, within 24 hours of a major earthquake.”
Other parts of the system may not be able to withstand a major earthquake, but Rhodes said this project “takes us one step closer” to that goal. The upgrade is part of a $4.8 billion SFPUC Water System Improvement Program consisting of 83 projects in seven counties.
The Harry Tracy Water Treatment Plant treats about 19 billion gallons of water each year. Water from Hetch Hetchy flows into Crystal Springs Reservoir and San Andreas Lake before being treated as drinking water.
Drinking water for SFPUC customers comes from the Hetchy Hetch Reservoir in Yosemite National Park so seismic upgrades may be needed at other points between Hetchy Hetch Reservoir and SFPUC customers. SFPUC general manager Harlan Kelly Jr. said the project represents a wise investment of customer dollars to improve the drinking water system’s reliability.
Customer rates went up because of the project, but San Francisco voters approved a measure that allowed the SFPUC to sell bonds to finance the improvement program. The commission is paying for the bonds by increasing water rates gradually. Rhodes said rates have tripled in about 10 years, which is what the commission had predicted when the measure passed.
The largest part of the project at the treatment plant was the construction of a new 11 million gallon reservoir of treated water. During construction, the discovery of a new fault trace caused a redesign and rebuild of the reservoir, which cost about $50 to 60 million, Rhodes said.
Kelly said the Harry Tracy Water Treatment Plant treats about 19 billion gallons of water. The upgrade will give more than one million Peninsula residents access to this supply after an earthquake.