Ozone treatment disinfects stormwater

ENCINITAS, Calif.—The American Public Works Association recognized the city of Dana Point, Calif.’s Salt Creek Urban Runoff Treatment Facility as one of its Public Works Projects of the Year for 2006. Salt Creek Beach and South Monarch Beach, two popular recreational areas in southern Orange County, Calif., had been struggling against frequent beach closures related to unhealthy levels of bacteria in the water. Even after an aggressive campaign by the city to investigate pollutant sources and implement source-control programs, postings were not reduced appreciably.

The city of Dana Point, working with water treatment experts from PBS&J, chose to disinfect stormwater with an ozone treatment system. While ozone treatment has been proven at potable water treatment plants and world-class aquariums and zoos around the world, treatment of stormwater with ozone is considered unique.

The Salt Creek Urban Runoff Treatment Facility began operating in 2005. Within days of initial start up, bacteria levels downstream from the facility were significantly reduced. Furthermore, operational flexibility provided in the design of the facility made it possible for city staff to accommodate anticipated changes in influent water quality and to assure that any residual ozone could be removed from the water before being released back into Salt Creek. In addition, PBS&J staff helped the city secure the largest single award of a Clean Beach Initiative Grant in California history.