ASR Interest Grows in District
As the Central Texas Hill Country and I-35 populations continue to grow, so will demands on water resources. To adequately plan for that growth, many water suppliers and utilities are exploring alternatives to diversify their supply sources and their long-term water supply strategies. Some of those strategies include brackish & desalination systems, water reuse, rainwater harvesting, and aquifer storage & recovery (ASR) systems.
Many water managers expect ASR to become an increasingly important tool for meeting future water demand as it has become a well-established technology used to improve the management of water resources in the state.
ASR is the injection (through a well) and storage of water in a suitable aquifer formation during times when water is available, and the recovery of that stored water during times when it is needed. If properly engineered and operated, the water stored in an aquifer storage and recovery system is not subject to the evaporative losses encountered in surface storage reservoirs and remains available for future use. Furthermore, ASR systems have a small footprint relative to surface-water reservoirs.
ASR activities in Texas began in the 1940s in El Paso and Amarillo and there is currently over 130 aquifer recharging programs across the United States. In Texas, there are some utilities that have successfully used ASR systems for a number of years such as San Antonio, El Paso, and Kerrville.
There are two local water suppliers in Hays County who have taken steps to perform feasibility and pilot tests for ASR. District staff have worked closely with the ASR project teams at the Ruby Ranch Water Supply Corporation (RRWSC) and City of Buda to collect data and review project plans. BSEACD has set aside 2 cfs (472 MG/yr) of freshwater Edwards for ASR projects to be used during non-drought conditions. The District hopes that such water strategies will reduce dependence on the Edwards during times of drought and during peak demand.
RRWSC completed a four-phase ASR pilot study in September 2019 in an effort to learn more about the feasibility of injection freshwater Edwards into the Middle Trinity Aquifer. RRWSC has an existing Edwards and Trinity well pair. The project reports that have been developed describe the results of the testing. RRWSC has received an ASR permit approval from TCEQ and their application is expected to go before the BSEACD Board for approval in early summer 2020.
The City of Buda started exploring (ASR) as a viable water management option in 2016 when they completed a feasibility study to inject freshwater Edwards Aquifer water into the Middle Trinity Aquifer. To move forward with a pilot project the City identified the project site near the Garlic Creek Booster Station and developed construction plans for drilling a Trinity Aquifer well near their existing Edwards Aquifer well. The project broke ground in early April 2020 and will be completed in different phases over the next year. The Trinity well is scheduled to be completed by June 2020, then the cycle testing injection and sampling process will begin.
The cycle plan will involve multiple relatively short tests of injection, storage, and recovery. Water samples will be collected to evaluate water quality changes of the stored water as it is progressively recovered. This testing will help determine how much water can be recovered and if there are any chemical reactions with the native groundwater or hydrogeological formation. The last of the cycles will include a larger volume of water and provide a longer storage period. Once all results are in and the TCEQ (Texas Commission on Environmental Quality) and BSEACD give final approval, the City can use this as a reliable source to bring online in their distribution system.
From there the City can begin injecting water into the Trinity aquifer where it will stay in place and create a storage bubble that can then be utilized during summer months when peak demand is high, or when drought conditions occur. During drought when Edwards Aquifer production is curtailed, the City hopes to recover and rely on water that was stored in excess times for the benefit of the City.