“Guidelines for Assessing the Feasibility of Aquifer Storage and Recovery”

By: Aaron Collier, P.G., and Hughbert Collier, Ph.D., P.G.

Aquifer Storage and Recovery (ASR), the injection and storage of water into a subsurface formation for later extraction, is rapidly gaining attention in Texas. Although there are only three operational ASR systems in Texas, a number of municipal as well as industrial water consumers are starting to show increased interest in technology. In Texas this flood of interest is being driven, in no small part, by changes to state regulations governing ASR.

ASR has a proven track record in Texas and throughout the country. However, the feasibility of ASR for a particular water system is best determined by answering several questions. This talk will review the essential components of an ASR feasibility study, along with case studies.

Phase I of assessing ASR feasibility is a desktop study consisting of two parts: Viability and Degree of Difficulty Assessments. The Viability Assessment identifies any fatal flaws by reviewing readily available data on the client’s water needs. the availability of source water, potential injection horizons, water supply contracts, regulations, etc. The second part is a Degree of Difficulty Assessment. This is an analysis of the amount of effort required to achieve technical success, safeguard public health and the environment, and regulatory approval. Components of this second part include geochemical and groundwater models, identifying any additional pre/post treatment of the water, and initial cost estimates.

Phase II is the collection of site specific hydrogeologic data (e.g. water samples, drill cuttings and/or cores, geophysical logs, pumping tests) from the potential injection zone(s) and the bounding confining formations. These data are used to refine the geochemical and groundwater models, which in turn determine the technical feasibility of ASR at a particular site. The data are also essential to the preliminary design of the ASR System.

This phased approach to ASR feasibility is the most cost effective and logical means of successfully engineering an ASR System.