AWWA ACE58117

Over the past several years the Santa Ana Watershed Project Authority (SAWPA) and the Chino Basin Desalter Authority (CDA) have been developing the Integrated Chino/Arlington Desalination System (ICADS) project to remediate the Chino Basin groundwater and in the process create a new local source of high quality potable water for the southwestern region of the Inland Empire, encompassing areas of both Riverside and San Bernardino Counties. Two critical aspects of the ICADS project involve the expansion of the Chino I Desalter, an existing reverse osmosis (RO) treatment plant, and the construction of the new Chino II Desalter, both of which must treat a groundwater supply with high concentrations of nitrate and total dissolved solids (TDS). The elevated nitrate concentrations, the result of the infiltration of runoff from large agricultural operations in the vicinity, are of particular concern, as levels could potentially exceed 200 mg/L (as nitrate), over four times the maximum contaminant level (MCL) and some of the nation's highest concentrations for a municipal drinking water source. An innovative process of utilizing RO and single pass ion exchange (IX) in parallel was determined to be the optimum solution to reduce TDS and nitrate to produce high quality potable water. Under this treatment scheme, since nitrate removal via IX is operationally less expensive, the flow to this process is maximized. The balance of the flow is treated via RO, which removes a very high level of TDS (including nitrate). The innovative treatment scheme and collaborative approach adopted for the Chino I and II Desalters is helping to enable the ICADS project to both remediate the Chino basin groundwater and provide the customers of the CDA member agencies with a high quality local supply of drinking water to meet the needs of numerous rapidly growing southern California communities. Includes 6 references, tables, figures.