Managed Aquifer Recharge Frequently Asked Questions

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Using recycled water is a viable option to reduce water shortages. Recycling water through managed aquifer recharge (MAR) is emerging in and abroad as an innovative and environmentally friendly treatment option.

What is Managed Aquifer How does MAR work? Infiltration galleries: buried trenches (containing polythene cells or slotted Recharge (MAR)? In Australia a variety of methods pipes) in permeable soils that allow Managed Aquifer Recharge is the are used for MAR: infiltration through the unsaturated zone process of adding a water source such Aquifer storage and recovery (ASR): to an unconfined aquifer (for example as recycled water to aquifers under injection of water into a well for storage Floreat Park, WA, see figure 1). controlled conditions for withdrawal and recovery from the same well. This is Soil aquifer treatment (SAT): treated at a later date, or used as a barrier to useful in brackish aquifers, where storage sewage effluent is intermittently prevent saltwater or other contaminants is the primary goal and water treatment infiltrated through infiltration ponds from entering the aquifer. Water can is a smaller consideration (for example to vary the amount of oxygen present be recharged by a number of methods Grange golf course, ). including infiltration via basins or galleries and facilitate nutrient and pathogen or by the use of injection wells. Aquifer storage, transfer and recovery removal during passage through the (ASTR): involves injecting water into a unsaturated zone before recovery by well for storage, and recovery from a wells after residence in the unconfined What sort of water can different well. This is used to achieve aquifer (for example Alice Springs, NT). be used for MAR? additional water treatment in the Percolation tanks or recharge weirs: aquifer by extending residence time in Many different water types can be dams built in ephemeral detain the aquifer beyond that of a single well used as a source for MAR. Current water which infiltrates through the (for example Parafield Gardens, SA). successful MAR schemes in Australia bed to enhance storage in unconfined have been using drinking water, captured Infiltration ponds: involve diverting aquifers and is extracted down-valley , and treated wastewater. surface water into off- basins (for example Callide Valley, Qld). The water used can depend on what is and channels that allow water to soak Recharge releases: dams on ephemeral available, the conditions of the aquifer through an unsaturated zone to the streams are used to detain flood and the uses of recovered water. underlying unconfined aquifer (for water and uses may include slow example Burdekin Delta, Qld). release of water into the streambed downstream to match the capacity for infiltration into underlying aquifers, thereby significantly enhancing recharge (for example Little Para River, SA).

Reuse Inspection lid Day 75 What effect does the MAR Day 1 process have on the water? Concrete discharge 0.5 m Inflow pipe chamber 12.5 m As the treated water infiltrates the soil and aquifer natural biological, 0.5 m chemical and physical processes occur to remove pathogens, chemicals and Slotted pipe nutrients from the water. This ‘filtering’ Infiltration with in situ soil process continues while the water infiltrates and resides in the aquifer.

Day 5 table

>>Figure 1: Cross-section of an Aquifer infiltration gallery. This is compatible with recreational land uses. The following water quality improvements occur during the process: • Attenuation of nutrients such as inorganic phosphates and nitrogen as well as most organic compounds How long will it be before >>One of two water recovery wells • Degradation of trace chemicals Australia can reliably call on at the ASTR well field at Parafield Gardens, South Australia. One of the such as disinfection by-products MAR water as a source? four stormwater injection wells is • Pathogen die-off MAR is already in use at various sites 50 m further on behind the trees. in Australia. CSIRO scientists have led The majority of this treatment occurs research at demonstration projects across through the activity of naturally occurring the country. They had a major role in the micro-organisms in the aquifer. As long development of the national guidelines as these micro-organisms remain active for MAR. These guidelines follow a risk the process remains sustainable. The management framework and give specific ability to remove contaminants from the Do other countries use MAR? guidance on managing the health risks and water significantly reduces the health and the environmental risks associated with MAR is actively and successfully used environmental risks that may be associated recharging aquifers with all sources of water in the USA, Europe, South Africa, India, with secondary treated wastewater, leaving including recycled water for a range of uses. China and the Middle East. Unesco the reclaimed water in similar quality to and the International Association that of the surrounding groundwater. The guidelines were endorsed by three of Hydrogeologists. (IAH) have Ministerial Councils of the Council of established the MAR-NET network Australian Governments and released How will we be using to help inform and build capacity on in August 2009. They are now part the MAR water? MAR for drinking water supplies. of the Australian Recycled Water The main purpose of aquifer recharge is Guidelines and will help to facilitate wider to store excess water for later use, while uptake of this innovative approach. For more information on Managed Aquifer improving water quality by recharging Recharge please contact: the aquifer with high quality water. If What are the health risks the groundwater is too salty for use associated with using MAR? Dr Peter Dillon then recharge with fresher water will Stream Leader Recycling and Diversified Supply displace the saltier groundwater. Wherever recycled water is used, Land and Water Phone: 61 8 8303 8714 strict Health Department guidelines MAR increases water storage in the aquifer Email: [email protected] for water quality and management which can make more water available for including watering times must be met. Dr Simon Toze irrigation and other uses and also to preserve Microbiologist water levels in wetlands that are maintained Extensive work is carried out to ensure Land and Water by groundwater. Groundwater recharge that recycled water schemes are Phone: 61 7 3214 2698 may also be used to mitigate or control designed and monitored to minimise Email: [email protected] saltwater intrusion into coastal aquifers. any environmental impact. Each scheme International Association of must be individually approved by the The water withdrawn from the aquifer Hydrogeologists Commission on MAR State/Territory Health Departments can be used to irrigate green open spaces, (incl. MAR-NET) on a ‘fit for purpose’ basis, depending www.iah.org/recharge VRU 2010 • WfHC_MAR-FAQFactsheet.indd namely parks, ovals and golf courses, which on the extent of human exposure. generally use large quantities of water. All major schemes require How much water can be evaluation for chemicals, radiation, supplied through MAR? pathogens and heavy metals. Various States are aiming to supply How does the cost of additional water through MAR. The South supplying water through MAR Web: www.csiro.au/flagships Australian Government, through its Water for Good Plan, calls for 60GL stormwater compare to desalination? harvesting via MAR in by 2050 It costs much less to treat and use and a further 15 GL/yr in regional SA. stormwater or reclaimed water using MAR (SA Government 2009). In addition, than seawater desalination; however should MAR planning and pilot projects are high quality water be required the reclaimed underway in three states (SA, WA, Vic) water may still need to be desalinated. As for subsurface storage of treated water there is much less salt in reclaimed water derived from sewage treatment plants, with than seawater, significantly less energy is a combined capacity of more than 30GL/yr. required to desalinate reclaimed water.