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Zone 7's Patterson Pass plant shifts to ozonation water treatment process

Replaces chlorine as main disinfectant, enhancing quality of outgoing water

Some of the upgrades to the Patterson Pass Water Treatment Plant include renovated pump stations. (Photo courtesy of Zone 7 Water Agency)

Residents in the Tri-Valley region will start to see and taste a difference in their tap water thanks to upgrades made to the Patterson Pass Water Treatment Plant in Livermore.

The Zone 7 Water Agency held a ribbon-cutting ceremony last Thursday to celebrate the opening of the newly renovated plant, which cost $110 million for planning, design and construction.

Improvements to the plant included installation of ozone treatment facilities, aging equipment and increased treated water storage capacity with the addition of a new, five-million-gallon tank. The plant will now be able to double the amount of treated water the plant can produce, from 12 million gallons of water a day to 24 million gallons a day, according to a Zone 7 news release.

Zone 7 board of directors Olivia Sanwong, Angela Ramirez Holmes, Sandy Figuers and Laurene Green cut the ribbon during Thursday grand opening ceremony. (Photo courtesy of Zone 7 Water Agency)

After decades of planning, the project was completed in spring 2022, after the Zone 7 Board of Directors approved the construction in 2019.

"By investing in best-in-class technology, Zone 7 demonstrates our commitment to high-quality water," Board President Angela Ramirez Holmes said in a statement. "Ozonation is a proven, successful treatment method that will improve our water, making it cleaner, safer and better tasting -- straight from the tap."

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The ozonation project is the latest investment to make the treatment process more efficient and improve water quality to better serve the community, according to Zone 7. How the new process will work is ozone will be injected into water and immediately start oxidizing and eliminating contaminants.

According to Zone 7, the Patterson Pass Water Treatment Plant, which has been serving the agency since 1962, has been treating imported surface water from the adjacent South Bay Aqueduct using dual-media filtration and chlorine treatment techniques.

But this has not been as effective in recent years at addressing high levels of organic matter and more frequent algae blooms that can cause taste and odor problems. Algae blooms are rapid increases or accumulations in the population of algae in freshwater or marine water systems that can produce dangerous toxins.

"The blooms are normal but are becoming more frequent," according to Zone 7. "After reviewing various treatment technologies, Zone 7 selected ozone to replace chlorine as the main disinfectant, resulting in higher quality water provided to customers by reducing chlorine-related byproducts and killing even more pathogens than chlorine."

Zone 7 supplies water to all of eastern Alameda County and sells wholesale treated water to local retailers, including the cities of Livermore and Pleasanton, the Dublin San Ramon Services District and the California Water Service Company. The public agency is also responsible for flood control in the Livermore and Amador valleys.

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Christian Trujano
 
Christian Trujano, a Bay Area native and San Jose State alum, joined Embarcadero Media in May 2022 following his graduation. He is an award-winning student journalist who has covered stories in San Jose ranging from crime to higher education. Read more >>

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Zone 7's Patterson Pass plant shifts to ozonation water treatment process

Replaces chlorine as main disinfectant, enhancing quality of outgoing water

by / Pleasanton Weekly

Uploaded: Tue, Jun 14, 2022, 7:06 am

Residents in the Tri-Valley region will start to see and taste a difference in their tap water thanks to upgrades made to the Patterson Pass Water Treatment Plant in Livermore.

The Zone 7 Water Agency held a ribbon-cutting ceremony last Thursday to celebrate the opening of the newly renovated plant, which cost $110 million for planning, design and construction.

Improvements to the plant included installation of ozone treatment facilities, aging equipment and increased treated water storage capacity with the addition of a new, five-million-gallon tank. The plant will now be able to double the amount of treated water the plant can produce, from 12 million gallons of water a day to 24 million gallons a day, according to a Zone 7 news release.

After decades of planning, the project was completed in spring 2022, after the Zone 7 Board of Directors approved the construction in 2019.

"By investing in best-in-class technology, Zone 7 demonstrates our commitment to high-quality water," Board President Angela Ramirez Holmes said in a statement. "Ozonation is a proven, successful treatment method that will improve our water, making it cleaner, safer and better tasting -- straight from the tap."

The ozonation project is the latest investment to make the treatment process more efficient and improve water quality to better serve the community, according to Zone 7. How the new process will work is ozone will be injected into water and immediately start oxidizing and eliminating contaminants.

According to Zone 7, the Patterson Pass Water Treatment Plant, which has been serving the agency since 1962, has been treating imported surface water from the adjacent South Bay Aqueduct using dual-media filtration and chlorine treatment techniques.

But this has not been as effective in recent years at addressing high levels of organic matter and more frequent algae blooms that can cause taste and odor problems. Algae blooms are rapid increases or accumulations in the population of algae in freshwater or marine water systems that can produce dangerous toxins.

"The blooms are normal but are becoming more frequent," according to Zone 7. "After reviewing various treatment technologies, Zone 7 selected ozone to replace chlorine as the main disinfectant, resulting in higher quality water provided to customers by reducing chlorine-related byproducts and killing even more pathogens than chlorine."

Zone 7 supplies water to all of eastern Alameda County and sells wholesale treated water to local retailers, including the cities of Livermore and Pleasanton, the Dublin San Ramon Services District and the California Water Service Company. The public agency is also responsible for flood control in the Livermore and Amador valleys.

Comments

Ko
Registered user
West of Foothill
on Jun 22, 2022 at 8:21 am
Ko, West of Foothill
Registered user
on Jun 22, 2022 at 8:21 am

Good to know. Hopefully this will help get Pleasanton water quality up past "bad" when algae is going wild. What aging equipment was replaced? Presumably better filtering but that was unclear.


keeknlinda
Registered user
Vintage Hills
on Jun 22, 2022 at 2:30 pm
keeknlinda, Vintage Hills
Registered user
on Jun 22, 2022 at 2:30 pm

At the ribbon-cutting, which I attended, it was made clearly known that the Patterson Pass facility has come online after the Del Valle treatment plant switch to zonation was completed in early 2021. Much of the Tri-Valley service area already has been receiving ozone-treated water from that plant. Zone 7 has operated the two plants for some years, and location within that service area determines which plant's water your home gets.
Pleasanton was changed over in 2021 and there was a change that improved the algae issue more than a year ago. Many people noticed it, others did not and continued complaining about the water. Some portions of Livermore didn't get that better-tasting advantage until Patteron Pass came online.
Because Pleasanton is supplied from both surface water through the Delta and groundwater, the origination of the supply is blended, 70-80% surface, the remainder groundwater. Because the drought has reduced the amount of surface water available through the State Water Project over the past couple of years, a greater ratio of groundwater is being used. And groundwater is inherently hard water.
Regarding what equipment was replaced, the whole plant was torn down and a new one built, so all equipment is new, and rather than the previous chlorination method, ozonation is now being used. Del Valle plant was modified, but Patterson Pass was simply replaced.
One of the biggest advantages of ozone treatment is how effective it is at treating that periodic algae issue that sometimes occurs in summer. Taste and odor are most effectively treated with ozone, thus allowing more consistently good-tasting water coming from your tap.
For more information, visit www.zone7water.com and you can read about the entire treatment operation.


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