Standard Guidelines for Artificial Recharge of Groundwater EWRI/ASCE 34-01

A review by Peter Dillon, CSIRO Land and Water, Australia

These guidelines describe the steps necessary to plan, design, construct, maintain and operate projects where water is applied to the land surface for infiltration or injected into aquifers via wells. The document is pitched at two levels. The first seven sections (52 pages of the 108 page volume) are at a very general level and would be easily read by people with no technical background. These sections discuss the basic principles of groundwater management and artificial recharge and the planning, investigation and design methodologies at a first-principles level. Technical matters are introduced at concept level only, and there are neat summaries of regulatory (for the United States), environmental, social, economic and financial considerations. The main aim is to raise awareness of the complexities and to ensure that potential proponents of projects to manage aquifer recharge are aware of the breadth of considerations and the costs of appropriate panning and community liaison.

The remainder of the guidelines are of more direct value to technical staff who have some understanding of the concepts and a desire to be aware of more specific considerations in construction, operation and maintenance procedures for surface infiltration, including soil aquifer treatment (SAT) of effluent and aquifer storage and recovery (ASR) projects (that is injection and recovery using the same well). The coverage is still at a relatively general level and abundant references are provided for those seeking more detailed information. Some examples of forms used for data compilation at managed aquifer recharge site are presented to give some concept of the level of management required for effective site operation and maintenance.

It is pleasing to see that these guidelines embrace the managed recharge of stormwater and treated effluent, although there was no reference to advances in Europe and Australia in this field. A view that ASR injectant requires disinfection was unchallenged in these guidelines, in spite of European regulations discouraging this practice and substantial evidence that pathogen inactivation occurs naturally in aquifers. Evidence of viral attenuation in aquifers is in fact stronger than evidence for attenuation of some disinfection byproducts under some conditions and Australian and European experience has proven that there are alternatives to disinfection for preventing biofouling of wells.

Guidance on pharmaceutically active chemicals/endocrine disruptors in recharge of reclaimed waters is sparse, due to the current state of knowledge and this is an issue warranting further consideration when research is more advanced. Some potentially significant geochemical issues were unmentioned, such as arsenic, fluoride and radon in recovered waters, however these should be adequately covered at any site if the principles outlined in the guidelines are thoughtfully followed. Another issue not addressed is the implications of future changes in energy costs on selection of project alternatives. The possibility for conjunctive storage of energy (heat) and water is not mentioned within the guidelines.

In summary, the guidelines summarize common sense approaches to managed aquifer recharge. (‘Artificial recharge’ is an unfortunate historical name – do we call production wells ‘artificial discharge’?) These should encourage appropriate effort in investigation and establishment of projects and provide better operational data from which continuous improvements can be made. With the caveats above, I would recommend the Standard Guidelines to proponents of new projects, consultants and regulatory agencies in the USA and elsewhere. These should raise the level of appreciation that successful projects arise from a sound understanding of sites, processes, technologies and local social, environmental and economic issues, developed in a systematic manner. This volume should also spur further investment in research and consulting to address gaps in knowledge of processes and site characteristics and thereby avoiding failures and increasing public and investor confidence in this expanding field of environmentally sensitive water management. Congratulations to the committee headed by Ivan A Johnson, who developed the Standard Guidelines for completing a formidable and open-ended task with such a positive and useful outcome. The guidelines can be purchased from the ASCE Publications department by visiting www.pubs.asce.org or call (800) 548-2723 or (703) 295-6300 (international).