Implications of soil aquifer treatment for sustainable water reuse on groundwater quality

This presentation will present an overview of a multiple-year program of study to establish the efficacy and sustainability of wetlands and soil-aquifer treatments leading to indirect potable water reuse. Wetlands and infiltration/subsurface treatment will be considered as a single treatment system for purposes of aquifer protection - primarily protection from nitrate and dissolved organics of wastewater origin. Soil-aquifer treatment is envisioned as consisting of (i) infiltration through a biologically active infiltration interface (<1m in depth) at the soil/water boundary of the infiltration basin; (ii) percolation through an extensive vadose zone, 10-100 feet in depth; and (iii) storage/transport in the underlying aquifer (6-24 months, >500 horizontal feet) pending withdrawal at proximate production wells. Water quality benefits in terms of organic carbon, nitrogen and pathogen attenuations will be assigned to each treatment zone based on the proposed field program and supporting laboratory experiments. At least seven field sites have been selected for use in the study based on specific strengths such as depth to groundwater, quality of groundwater data, instrumentation and geographical considerations. Results will be analyzed within a systems framework that can be driven by local data and constraints from other geographical locations. A multidisciplinary team consisting of environmental researchers from three western states; water and wastewater practitioners from Arizona and California - states that will eventually depend heavily on wastewater reclamation/reuse to meet water demands; and experts in (aquatic) organic chemistry, virology, hydrology and systems analysis has been identified to overcome these shortcomings. The proposed project will generate practical tools with which to assess water quality and/or gage compliance with regulatory (reuse) criteria.