More than a decade after the Zone 7 Water Agency started planning, the long-awaited expansion and upgrade of the Patterson Pass Water Treatment Plant will finally get underway next month.
No major upgrades have happened in more than 15 years, and once work is finished, officials say the agency will be in a much better spot down the road.
"It's our oldest plant and so it's time for a major upgrade and overhaul," Zone 7 General Manager Valerie Pryor told the Weekly. "Basically, we're almost doubling the size for 24 million gallons per day, and that's to meet what we perceive to be future demand."
The plant will also "provide redundancy" in case of potential power outages and emergencies at other treatment plants like Del Valle, which is also currently undergoing similar renovations.
Improvements will cost approximately $110 million, including planning, design and construction, and are funded by a mix of bonds, water rates and new connection fees. Agency staff advised the Board of Directors, which unanimously approved the contract at its Feb. 6 meeting, that delaying the project could put Zone 7 at risk of paying more in the future.
The scope of work planned includes an ozonation project, which will add a new ozone generation building, ozone contactor structures, filters, chemical storage and feed facilities, a 5-million-gallon treated water storage tank and a pump station to the plant site.
Some older facilities such as the previous ultra-filtration pond, chemical facilities and washwater recovery ponds will be demolished or modified.
Many water treatment plants now use ozone disinfection, which is "very powerful" and "very effective ... for contaminants of emerging concerns" such cyanotoxins produced by blue-green algae, and pharmaceuticals, according to Pryor.
In addition to being better for killing viruses and bacteria than chlorine disinfection, customers might also notice their tap water tastes better, as Pryor said ozonation also great for addressing taste and odor complaints.
Work will break ground near the end of March and should take about three years to complete, Pryor said.