AWWA SOURCES59267

A recent AWWA Survey (2002) indicated that there are over 60 ASR projects nation- wide, albeit only about half are operational systems. Many of these systems are in areas where freshwater is injected into relatively fresh native water. Under this scenario, the limitations of the ASR systems are mostly related to geo-chemical and aquifer parameter concerns. However, where the freshwater is injected into brackish water, ASR technology is not as well understood. Questions arise about the effects of buoyancy on the migration of the water, how well the system will operate over large injection horizons and the effects of the aquifer formation. The current software (MODFLOW) is not sufficient to model ASR systems in brackish environments. As a result the authors have used SEAWAT, a USGS density-driven model that links MODFLOW and MT3D-MS in a density-driven protocol, to look at these effects on the City of Fort Lauderdale's ASR well. Modeling ASR systems successfully will provide a tool for answering more extensive questions on non-potable ASR systems that might use surface waters or wastewater effluent. Modeling of such ASR systems will be needed to answer concerns about nutrients, pathogens and potentially more exotic public health concerns such as endocrine disruptors. The results of the modeling will shed light on limitations identified by the authors over the past several years, and provide some guidance as to their solutions. Includes 10 references, tables, figures.