The development, application and acceptance of environmental and health risk assessment methodology for MAR schemes in South Australia

Abstract

A risk assessment methodology for the establishment of Managed Aquifer Recharge (MAR) schemes has evolved in South Australia (SA) over the last 6 years. The methodology is based on the Australian Guidelines for Water Recycling and has been led by the Environment Protection Authority (EPA) in close collaboration with the Department of Environment, Water and Natural Resources (DEWNR), Department of Health and Aging (SA Health) and industry. MAR has been established in SA as a common practice over the last 20 years. Early Aquifer Storage and Recovery (ASR) schemes were supported and initiated by DEWNR (in various guises) to explore viability and recharge depleting aquifers. Large areas of the Adelaide Plains, across where the state’s capital sprawls are underlain by a tertiary aquifer system that lends itself to MAR. Local councils and catchment boards embraced the practice and the Commonwealth Scientific and Industrial Research Organisation Land and Water proceeded with an extensive programme of research and documentation of existing and emerging MAR practices. ASR of treated wastewater was trialled and a pilot scheme established by SA Water which is now operational. Early schemes were not rigorously regulated but up to five state agencies are now involved because of their legislative responsibilities. DEWNR regulates water quantity, EPA water quality and SA Health the impact of use on human health. Most of the legislation was written prior to MAR practices and has been applied adaptively providing confusion and frustration for developers and operators. MAR schemes have proved successful and the number continues to increase boosted over the last 10 years by federal government initiatives promoting the use of recycled water, funding support and an extended period of drought. The Australian Guidelines for Water Recycling: Managing Health and Environmental Risks 2006 and Phase 2 Guidelines were developed detailing a health and environmental risk assessment framework that could be applied to recycled water schemes including MAR. The risk assessment methodology follows a stepwise approach to examining the source water, the receiving aquifer and the end-use. The requirements for developers and operators have increased over time and the risk assessment processes are now embraced and a Draft MAR Guide has been developed. There has been a collaborative effort by the agencies involved to streamline the process and the risk assessment methodology is a key binding force. Industry acceptance has not been smooth, adaption of regulation is ongoing, monitoring has been inconsistent and unexpected technical and water quality issues continue to arise; however, there are number of loose ends remaining to be tied.