Rinconada is the only one of the district’s three treatment plants that’s unable to use ozone to address taste and odor problems in the water. Penitencia and Santa Teresa have used ozone with great effectiveness to destroy those chemicals that cause those issues since 2005.
Ozone was first used in water treatment in the late 1800s and is now an attractive water treatment alternative. It is a powerful oxidizing agent that can reduce levels of many impurities in water, including color, taste and odor and can be used as a disinfectant and alternative to chlorine.
An effort to implement ozone at Rinconada fizzled in 2005 due to a lack of funding, but the Reliability Improvement Project does include the addition of raw water ozonation to the treatment process.
Adding ozone as the first step in the treatment process enables further enhanced filtration performance, though it does require use of more ozone than if it was added to the settled water. Under the project, the water district will build a new raw water ozone contactor in the plant area where there now exists a vacant dirt lot and will include two parallel basins to meet primary disinfection requirements for viruses as specified by the Surface Water Treatment Rule.
The rule from the U.S. Environmental Protection Agency seeks to prevent waterborne diseases caused by viruses by requiring that water systems filter and disinfect water from surface water sources to reduce the occurrence of unsafe levels of microbes. This phase of the project is scheduled to begin in 2017 and take about a year to complete.