Geotechnical aspects of groundwater recharge in arid regions

The use of ground surface infiltration basins for the replenishment of groundwater supplies is common practice in arid regions. Both relatively clean water and water of impaired quality, such as treated wastewater, are used for this purpose. The water is infiltrated through an unsaturated soil region to an underlying unconfined aquifer. The recharged water is subsequently recovered by pumping and reused. As water demands have grown, the recycling of wastewater has increased. When treated wastewater is used as the recharge source the process of infiltration through the saturated and unsaturated soil zones is referred to as Soil Aquifer Treatment (SAT) because additional cleanup of the wastewater occurs as it travels through the soil. Although the recycled wastewater is commonly used for nonpotable purposes such as landscape irrigation and power plant cooling, interest in reclaimed water as a potable supply is great. Several SAT sites are under study as a part of research conducted through the Center for Sustainable Water Supply at Arizona State University. The geotechnical considerations for SAT include primarily the evaluation hydraulic loading capacity of the site, maintenance of hydraulic loading capacity during basin operation, and study of the impact of soil type on water treatment.