The water 2.5 million Bay Area residents drink will be safer once a $112 million water treatment plant is open in 2012.
The multibillion-dollar Water System Improvement Project aims to protect The City’s drinking water supply from earthquakes and help the San Francisco Public Utilities Commission catch up on needed maintenance.
A portion of that project is a new water treatment site in San Joaquin County, where water will wash over ultraviolet light bulbs designed to kill stomach-infecting bugs before flowing through San Francisco taps.
A 14,000-square-foot building — where water will be treated and disinfected using chlorine, fluoride and other chemicals — is being built to replace the existing facility 8 miles south of Tracy at the Tesla Treatment Plant. The aging plant doesn’t meet modern earthquake, fire or building codes.
The new plant, which is expected to be fully operational by early 2012, will feature two consecutive treatment facilities.
After water is chemically treated, a neighboring 20,000-square-foot building will provide a new level of treatment that’s needed to meet guidelines updated recently by the U.S. Environmental Protection Agency to help protect the public from cryptosporidium.
Cryptosporidium is a type of microscopic parasite that causes severe stomach illness in humans and other animals. The parasites are protected by a shell that helps them survive for prolonged periods outside of their victims’ bodies.
The shell also makes the single-celled bugs difficult to kill using normal concentrations of chlorine. Ultraviolet light will be used at the treatment plant to help ensure that any cryptosporidium in San Francisco’s water supply is killed before it reaches a customer.
Water will flow at Tesla Treatment Facility past 10 to 12 ultraviolet lamp arrays, each arranged inside a large pipe and comprising scores of individual bulbs.
With a processing capacity of 315 million gallons of water per day, Tesla will be the nation’s third-largest ultraviolet water treatment facility and the biggest in California.
Construction of the new facilities will require a weekslong shutdown of water pipelines from Hetch Hetchy Reservoir to San Francisco.
To prepare for the shutdown, which was timed to coincide with a wintertime lull in water usage, Bay Area reservoirs are being filled up through an increased water flow from Hetch Hetchy.
Construction of the treatment plant is employing workers in the economically distressed San Joaquin Valley who lost jobs when a housing bubble-related construction boom ground to a halt last year.
“We’ve seen a real slowdown in construction,” San Joaquin County Supervisor Leroy Ornellas said. “There was so much construction going on that it started to create a life of its own.”
Construction of the plant began in May and work is expected to continue for two years.
The federal government requires less-intensive treatment of Hetch Hetchy water than water from most other sources because the Yosemite National Park snowmelt is considered pristine.
To comply with the EPA’s recently updated guidelines, most water agencies will filter water, chemically treat it and expose it to ultraviolet lights. San Francisco, on the other hand, secured a waiver allowing it to avoid filtration.
Groundwater to add to drinking water
Groundwater will be treated and mixed into San Francisco’s drinking water to help supplement snowmelt that flows from Hetch Hetchy Reservoir and water that’s tapped from creeks and rivers.
Up to six wells, each hundreds of feet deep, are planned in western San Francisco to extract 4 million gallons per day of water from the Westside Groundwater Basin.
The 45-square-mile basin is a series of aquifers extending from Golden Gate Park through San Bruno.
By 2013, the groundwater is planned to be disinfected and poured into the municipal drinking- water system.
“We are going to be blending very low quantities of groundwater,” Water System Improvement Project manager Julie Labonte said. “People are never going to see a difference.”
The blended water will be used mostly in the western part of San Francisco, where it could constitute up to 10 percent of the water that flows through taps.
Additionally, sewage is planned to be safely treated and used to irrigate golf courses that are presently watered using drinking-water
Protecting water delivery
The Water System Improvement Program is a $4.4 billion to $4.6 billion, 12-year effort to rehabilitate and protect the system of pipes, reservoirs and equipment from earthquakes. The entire system delivers water — largely from the Hetch Hetchy Reservoir in Yosemite National Park — to 2.5 million Bay Area customers.
By the numbers
12 feet Width of pipelines that carry water into the Tesla Treatment Plant
7.8 Magnitude of earthquake the new plant is designed to withstand
90 million Daily treatment capacity in gallons at existing water facility
20 million to 30 million Average gallons of water treated at existing facility
315 million Maximum treatment capacity in gallons at new water facility
2 Major water treatment plants in San Francisco’s water system
10 percent Portion of western San Francisco tap-water planned to come from groundwater sources