Estimation of Volumetric Capacity of an Aquifer Storage and Recovery (ASR) Field Operated By San Antonio Water System, Bexar County, Texas
Aquifer storage and recovery (ASR) is an established approach for storing available water in an underground geologic unit and recovering it to meet increased demand during drought or dry seasons. An ASR system's main component is a set of wells that inject and withdrawal water in cycles of injection, storage, and extraction. In 2004 San Antonio Water System (SAWS) began using its Twin Oaks ASR facility in southern Bexar County, Texas, with wells in the Carrizo aquifer, to store groundwater from the Edwards aquifer. The purpose of this study is to estimate the total capacity of the so-called "massive sand" in the Carrizo aquifer at the Twin Oaks ASR facility to store water. Thickness and porosity are determined from a number of geophysical well logs at and around the site. The study uses IHS Petra software program to generate a map of pore volume in the Carrizo Formation at the ASR facility. The total pore volume of the ASR site is estimated to be 233,400 ± 9000 acre feet.