Aquifer Storage Recovery
Aquifer Storage and Recovery (ASR) is the process of injecting water into an aquifer (an underground layer of rock or sediment that holds water) for storage and later reuse.
ASR is a modification of the natural system that has been occurring for millions of years. Natural recharge occurs by filtration of rainwater through the soil profile, past the vegetation root zone and down to permeable rocks known as aquifers. Artificial recharge at Salisbury occurs by pumping cleansed stormwater into a bore that is drilled into an aquifer.
Aquifers are natural storage mechanisms that can store large quantities of water. The T1 and T2 aquifers of the northern Adelaide plains formed millions of years ago from beach sands and marine life when sea levels were high. As sea levels receded, fine sediments were deposited and compacted resulting in the permeable, sandy limestone layers ‘sandwiched' in-between very dense, impermeable confining layers. Consequently theses aquifers are confined and injected water stays within near proximity of the injection bore.
Storing water within aquifers has numerous benefits – including lower losses than surface storages subject to evaporation and improved water quality through water percolating through the aquifer. ASR can also be used as a beneficial means of artificially recharging depleted groundwater reserves.
How does ASR work at Salisbury?
Cleansed stormwater from wetlands is pumped under pressure into a bore that is drilled into a confined aquifer. Pumping pressures are usually in the order of 300-500 kPA. Both the T1 & T2 sedimentary limestone aquifers of the northern Adelaide plains are utilised for ASR, with injection rates ranging from 10 litres per second in the T1 aquifer up to 40 litres per second in the T2 aquifer. Most of Salisbury's ASR schemes utilise multiple bores (wellfields). In the Salisbury area, the T1 aquifer is up to 160 metres deep and the T2 aquifer up to 220 metres below ground level.
The recycled stormwater injected is continually monitored via online sampling to ensure water quality criteria are met. The pressure in the aquifer is also continually measured to protect the integrity of the clay formations above the limestone aquifer (confining layer).
Recycled stormwater is very low in salinity and when injected into brackish aquifers forms a ‘fresh water plume' radiating out from the bore (point of injection). The size and shape of the plume is modelled by hydro-geologists and can be verified by monitoring an observation well, located a set distance from the point of injection.
Recycled stormwater is then recovered from the aquifer using submersible bore pumps before being distributed to customers.
Current ASR Sites within Salisbury
- Edinburgh Parks South – Edinburgh Road, Edinburgh Park
- Kaurna Park – Waterloo Corner Road, Burton
- The Paddocks – Maxwell Road, Para Hills West
- Parafield Airport – Parafield Airport, Parafield
- Greenfields Wetlands – Salisbury Highway, Mawson Lakes
- Unity Park – South Terrace, Pooraka.
Useful ASR Links
This Specific Targeted Research Project, supported by the European Commission under the Sixth Framework Programme, aims to develop hazard mitigation technologies for water reclamation providing safe and cost effective routes for artificial groundwater recharge.
Managed Aquifer Recharge
MAR involves adding a water source such as recycled water to underground aquifers under controlled conditions. A $3 million project will investigate the different aquifers across the Swan Coastal Plain in Western Australia that may be used for MAR schemes.