Capturing the lessons of ASR failure from trials in unconsolidated aquifers

In this paper the challenges in developing sustainable ASR operations in unconsolidated, low permeability aquifers, where operational problems such as well clogging tend to be more acute, are explored from the viewpoint of two case studies; one from Australia, the other from Thailand. Both studies were undertaken independently over different time-frames and brought together for comparative purposes. The Australian case study involved injection of wetland-treated urban stormwater into a low transmissivity, fine-grained siliceous aquifer; whereas the Thai case study involved injection of advanced-treated canal water into a colluvial/alluvial aquifer with high fines content. Although the design and execution pathways for the two trials were substantially different, ultimately the same endpoint (trial abandonment) was reached. This examination of the causative factors of failure, which were mainly related to poor recharge water quality for the Australian case, and poor hydraulic performance brought about by poor site selection for the Thai case study, lead to a number of key lessons being derived that could prove helpful to those considering ASR in similar environments.