AWWA WQTC65931

The West Basin Municipal Water District maintains a commitment to aggressive water conservation and recycling programs. This project is a continuation of that commitment and expands the Water Recycling Plant such that it will conserve over ten billion gallons of imported water annually. This project also reduces the impacts of increased disposal of wastewater and provides high quality water that can be safely returned to the environment via groundwater injection. The use of re-purified water at the barrier represents an innovative method to continue protecting local groundwater resources from seawater intrusion while conserving California's precious water resources. Ultraviolet (UV) oxidation is an important component for the West Basin Municipal Water District Recycled Water Project (WBWRP). The UV process will provide disinfection plus an additional barrier of photolysis and oxidation of complex compounds like N-nitrosodimethylamine (NDMA) and many emerging contaminants. This paper summarizes the successful UV strategy for complying with the California Department of Health Services (CDHS) draft Groundwater Recharge Reuse regulation, involving reduction of NDMA levels and addressing trace organics. Specific challenges on procurement, validation and monitoring are presented with solutions that were derived from three separate projects: WBWRP, Orange County Water District Groundwater Recharge and Los Angeles County Sanitation District Alamitos Barrier Project. Industry challenges are highlighted to illustrate information needed to optimize the operation of these projects. Includes tables, figures.