Guidelines on the Quality of Stormwater and Treated Wastewater for Injection into Aquifers for Storage and Reuse
This report was produced for the Urban Water Research Association of Australia, a now discontinued research program.
Urban storm-water and treated wastewater generated in wet months can be used as a water resource in dry periods if they can be stored. Aquifers may provide adequate and cost-effective storage below ground, but need to be protected from contamination. A major barrier to the storage of reclaimed waters in aquifers via injection wells (ASR) has been a lack of scientifically based guidelines for the quality of water to be injected. This report expands on previous documents on artificial recharge or reclaimed waters (AWRC 1982, and NRC 1994)and is a first attempt (internationally) to provide a sound basis for the injection of non-potable waters into aquifers for a range of beneficial uses.
This study has reviewed international practice and guidelines for artificial recharge of reclaimed waters by injection. It has given particular attention to relevant existing Australian guidelines and aimed to refine and improve these. The resulting draft guidelines draw on Australia’s existing National Water Quality Management Strategy (NWQMS)) for its principles, objectives, and for guideline values for maximum contaminant levels in water for a range of beneficial uses. They also take account of scientific evidence on:
- The quality of urban storm-water and treated wastewater
- pre-treatment performance of passive systems
- clogging and redevelopment of injection wells
- attenuation of chemical and microbiological contaminants in aquifers
- preliminary results at a pilot study of ASR using storm-water
These guidelines adhere to widely accepted principles but are quite different from those currently used to regulate ASR sites in other parts of the world, as they do not presume potability as an essential objective, and they allow for treatment of water by natural processes in the aquifer. The guidelines are presented after consideration and comment on a draft by water companies and other potential proponents of ASR-based water supply/wastewater reuse schemes, and by state and federal authorities with responsibilities for licensing ASR facilities. Knowledge gaps are also revealed which may focus research to enable these guidelines to be improved.
The guidelines, which are summarised (in section 9) cover licensing, pre-treatment, monitoring, guidance for maximum contaminant concentrations in injectant, residence time prior to recovery, and management of ASR operations. The report also makes recommendations (in section 10) on; revision of these guidelines; concentration of research at selected sites; and establishment of a national ASR research program to coordinate and conduct ASR research, to collate all monitoring data and reports from Australian ASR sites, and to produce a design manual for ASR.