Change to Ozone Disinfection ? February/April 2010
An important part of the Miramar Water Treatment Plant Upgrade and Expansion Project is to change the water disinfection method from chlorine to ozone. This change will meet new water quality requirements for the plant.

Ozone disinfection is a highly effective way to eliminate any germs and viruses in water. This method has been used at drinking water plants for more than 100 years. Often, customers report improved taste and odor in water disinfected by ozone, as compared to chlorine.

Chlorine will still be used at the plant. Before the ozonated water leaves the treatment plant on its way to storage tanks and pipelines throughout the city, chlorine will be added to provide a disinfectant ?residual.? This keeps the water disinfected in the delivery system before it is used by customers.

Safety Alarm Testing ? February 2010
Starting in February, the construction team is testing and implementing the new ozone disinfection system safety alarms. These alarms ensure safe operation of the plant and alert employees to matters needing attention. Alarms may be heard outside the ozone building during construction working hours, weekdays, from 7 a.m. to 5 p.m.

The outdoor alarm volume will be lowered and muffled as much as possible. At certain times, the alarms will need to be tested at full volume. There is no danger to the community or to the drinking water when the alarms are activated.

Ozone Disinfection System Start-Up February ? April 2010
The start-up phase of the ozone disinfection equipment will occur from February through April. Muffled and full volume alarms may be heard during normal construction working hours, weekdays, from 7 a.m. to 5 p.m., or possibly after hours.

The ozone disinfection system shuts itself down if it detects any problems. If the ozone system needs to be taken off-line for any reason, the chlorine disinfection system is activated. The water is safe to drink and there is no danger to water customers or the community.

An ozone disinfection system is also being installed at the City?s Alvarado Water Treatment Plant to replace the current chlorine disinfection system and is expected to be operational in June 2010.

• Ozone Disinfection Frequently Asked Questions (PDF)