AWWA JAW70293

Arsenic leaching in aquifers has become a problem for aquifer storage and recovery (ASR) operations. The highly oxidative nature of finished water causes arsenic in naturally occurring minerals to leach from aquifer formations. The authors evaluated the effects of lowering dissolved oxygen concentrations and removing chorine residual in injected potable water on arsenic leaching in storage aquifers. Using geochemical modeling, they predicted interactions between injected water and the stored aquifer formation and native water quality. The authors found that returning finished potable water to native groundwater quality through wellhead pretreatment may prevent naturally occurring arsenic from leaching from aquifers. In addition, existing pretreatment technologies can be implemented that make the injected water more compatible with the native aquifer quality. These pretreatment technologies could allow utilities to operate their ASR facilities in compliance with federal underground injection control regulations and drinking water criteria, thereby avoiding consent/administrative orders from regulatory agencies. Includes 41 references, tables, figures.