Some of the water that meanders down from the Sierra Foothills in the Mokelumne River will soon be dripping out of some local taps once the new city of Lodi Surface Water Treatment Plant comes online, likely later this month.
Local leaders gathered at the plant Thursday in front of the water system's main component — hundreds of six-foot-tall water pipes filled with tiny tubes that remove microscopic bacteria.
The celebration marks a more than 10-year process to replace some of Lodi's groundwater with river water. The new plant will replace 35 percent of the city's annual groundwater usage.
"It is important to our future," Public Works director Wally Sandelin said. "I think it won't be until maybe 30 years from now that our people in Lodi will look back and say, 'That was a pretty smart thing you guys did.'"
The city is currently running water through the system to complete the testing phase to meet California Department of Health Services requirements and receive the go-ahead to operate, chief water plant operator Andrew Richle said. He is hoping the plant will be able to start treating water for Lodi residents to consume by the end of the month.
Every day, the plant can treat up to 10 million gallons, which is equivalent to filling 521 in-ground 16-by-32 foot swimming pools.
So how does the plant work? The process starts in Woodbridge, where water flows into a 36-inch main near Woodbridge Dam and then three pumps send the water into the plant.
The water then goes into a sedimentation basin, where any big particles will settle to the bottom. After that, the water is sent through two strainers and enters the membrane system, which is the heart and the soul of the plant.
There are thousands of membranes that look like strands of spaghetti in each of the 6-foot-tall modules. In total, there are 420 modules.
Pumps force the water through the membranes, which look like strands of spaghetti, in each module. The water runs through the tiny tubes, which filter out particles a fraction of the diameter of human hair.
The process removes tiny parasites like giardia lamblia and cryptosporidium, which can cause gastrointestinal illnesses. Richle said the plant's membrane is cutting-edge technology.
"It's an extra level of protection against bacteria and diseases getting in the water supply," Richle said.
Every 30 minutes, the system is cleaned. Air is pushed through the modules to loosen up any dirt, and then water that has already been treated rinses the filters clean. The now-dirty water is then taken out of the membrane building, sent to a sedimentation basin and then run back through the system to be cleaned again. The plant can recover 95 percent of the water that is used to clean the membrane system.
Once the drinking water is cleaned through the membrane system, it will be treated with the lowest amount of chlorine the state requires, Richle said.
Because the city installed the advanced membrane system, staff can use less chlorine than other plants, staff said. Also, the water quality of the Mokelumne River is higher than most rivers in the state, leading to less need for chemical treatment, he said.
"We think the less chemicals, the better when treating drinking water," Richle said.
The water will be stored in a 3 million-gallon tank, and then released through a 36-inch water main that runs down Mills Avenue. The line connects to the transmission lines where North Mills Avenue meets Turner Road, Yosemite Drive, Lockeford Street and Elm Street.
The amount of water the plant will pump into the water system will depend on the time of year and how much water Lodi Utility customers are using, Richle said. Residents will still get a majority of their water from 26 wells throughout the city, but the plant will provide 35 percent of the city's annual water.
The plant will be closed during the winter for anywhere from two weeks to a month, when the Woodbridge Irrigation District lowers Lodi Lake levels. The city will be able to use the break to clean the equipment.
In the future, the city could add another building with five more racks of membranes, allowing it to treat 20 million gallons a day and extend the water main on Mills Avenue, Richle said.
Opening up the ceremony, Mayor JoAnne Mounce congratulated city staff on the accomplishment and shared how she was initially disappointed that it was raining for the ceremony.
"But then, I thought, 'I guess raining is a good thing, because without the rain, we won't have the water to run through this wonderful plant which we are celebrating today,'" Mounce said.