DEVELOPING INDIRECT POTABLE REUSE TO INCREASE WATER SUPPLY, IMPROVE WATER QUALITY AND MANAGE WASTEWATER DISCHARGE IN ORANGE COUNTY CALIFORNIA

An indirect potable reuse project has been proposed by the Orange County Water District and the Orange County Sanitation District to produce a reliable supply of high quality, low salinity, water to recharge the local groundwater basin. This Groundwater Replenishment (GWR) System, will be implemented in three phases by the year 2020 and will ultimately reclaim 100,000 acre feet of wastewater per year (afy) using a membrane based desalting process. The project is possible because of advances in membrane processes, particularly microfiltration (MF) and reverse osmosis (RO), and is a logical extension of the existing wastewater reclamation process currently in operation at Water Factory 21 (WF21). The GWR System water will be available in all seasons and contain less dissolved solids than imported water from the Colorado River. The project will partially offset a possible reduction in expected water deliveries through the Bay Delta. Consequently the GWR System will provide significant relief to Orange County in times of drought and, by lowering TDS levels in the groundwater, will help mitigate the damages to water fixtures that result from increasing levels of salts in imported supplies. The project also supports the reclamation objectives contained in the Orange County Sanitation Districts Charter and provides an alternative to the construction of a new ocean outfall for the management of wastewater discharge under wet weather conditions.