Zone 7 breaks ground on $110 million treatment plant project

Patterson Pass capacity will double to 24 million gallons per day, officials say

Tri-Valley residents can expect better tasting and smelling water from the tap when the expansion and upgrades at the Zone 7 Water Agency Patterson Pass Water Treatment Plant are completed.

The decade-plus plan to increase capacity and improve water conditions at the plant in eastern Livermore finally broke ground at a ceremony last week attended by public officials including the Zone 7 Board of Directors, General Manager Valerie Pryor and Livermore Mayor John Marchand.

"Zone 7 was originally proposed to improve water quality back when I was on the board in 1991," said Marchand in a prepared speech. "I find it amusing when people are emailing that Zone 7 is 'rushing into this decision.'"

No major upgrades have been made to the agency's oldest plant in more than 15 years, and once construction is completed, the plant's size will double for 24 million gallons daily. Pryor previously told the Weekly "that's to meet what we perceive to be future demand," and that the plant will also provide redundancy during any power outages and emergencies at other plants like Del Valle, which also has similar work underway at the moment.

The project will cost an estimated $110 million, including planning, design and construction, and is funded by bonds, water rates and new connection fees. Work plans include an ozonation project, which will involve building a 5-million-gallon treated water storage tank, a new ozone generation building, feed facilities, ozone contactors, filters, chemical storage and a pump station to the plant site. Older facilities like the former ultra-filtration pond, chemical facilities and washwater recovery ponds will be modified or demolished.

Ozone disinfection "is one of the only things we can actually rely on in the future" to keep the water safe for the public, according to Zone 7 Director Sarah Palmer, who noted that the agency is saving money by simultaneously remodeling both the Patterson Pass and Del Valle treatment plants, even though Del Valle's amenities still "had a couple of years ahead at the time."

"This is actually really cheap, if we were to look at it in terms of what would happen if we had some problem like a cyanotoxin bloom," Palmer said. "We need to be able to handle it ahead of time, before it happens to us."

Many water treatment plants have switched over to ozonation, which is better at killing cyanotoxins produced by blue-green algae, as well as pharmaceuticals and viruses than chlorine disinfection. Ozonation also has the benefit of improving the taste and odor of water, which Marchand, a scientist specializing in water quality, said has been an issue for customers for a long time.

"It is difficult to convince someone that the water is safe to drink when it smells and tastes like a swamp or like dirt," he said. "I've had people tell me that their pets refuse to drink the water."

Work on the site is expected to take about three years to complete, according to agency officials.

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