Salisbury Aquifer Recharge and Recovery Scheme
Posted in Models, RDAG by CBiggs on August 7th, 2009
Location: Salisbury, Adelaide, Australia
The scheme started in the 90’s with progressive thinkers in the City of Salisbury authority trying to find a way to store water that could be used in summer and cut water costs. This original effort has expanded to include stormwater collection, wetland treatment and aquifer injection and retrieval.
One of triggers for the project was the prospect that a major water user (a wool processing facility) was considering relocation due to the cost of bringing over 1bn L of water per year from the river Murray which would have put hundreds of jobs at risk. In a joint project with the council, stormwater is now diverted from drains flowing to the sea and treated in nearby wetlands supplying the wool processor with an alternative local source.
Another larger treatment wetland also helps clean stormwater before it is injected into an aquifer. This water is used by a nearby Holden car manufacturer and other industries.
Today, storm water is collected from hard surfaces, including from residential homes and roads and treated through 250ha of constructed wetlands. The water is then pumped into an underlying aquifer and stored for 10 days before being extracted and re-used. Due to distribution costs, extracted water was initially piped only to the main water users and sold at a nominally lower than utility rates.
Extracted water is delivered to residential users for non-potable use after being mixed with higher quality water from the utility (to reduce salt levels). Residential connection is not complete. Greenfield developments are connected but existing houses must pay for the connection. The connection cost is waved as an incentive, if existing homes purchase rainwater tanks.
The distribution pipes do not have the capacity to meet all household’s demands but act to diversify supply. Thus, a home may source its water for external use with from rainwater, supplemented by aquifer treated storm water, with the utility’s potable water the final backup. This provides a range of options and shares risk.
Community concern is the main on-going driver of the scheme. Even the Council’s current roll-out of residential water-meters is mainly being driven by community demands. This is despite its high economic cost, which could be avoided by a fixed rate charge. Part of this community pressure stems from anger at recent restrictions on potable quality water from utilities.
Locals see the uniqueness and success of the storm water treatment wetlands as a key positive aspect of the area. The wetlands not only form an integral part of the suburbs’ identity, they provide important habitat for birds and recreational, aesthetic and educational value to the community. As Salisbury has been given a poor reputation by some people in Adelaide for being a low income, working class area, which its residents understandably resent, this is a significant positive development.
While the Council has relied on a centralised storm water collection system and the size of its wetlands to create an economy of scale in favour of smaller, more localised collection and treatment areas, it has opted for installing ‘rainvaults’ for collecting stormwater in higher density locations with a higher localised flooding risk. Water from the vaults is then pumped to the wetlands. The council sees this more in line with community wishes than following economic sense but also notes that using the vaults instead of centralised distribution infrastructure means periodic infrastructure renewal costs are avoided over the long-term.
www.gtasa.asn.au/file.php?f=A9-3ik.OnaGSo.46 /
http://cweb.salisbury.sa.gov.au/manifest/servlet/page?pg=16064
www.aila.org.au/projects/SA/paddocks/docs/wetlandspaper.pdf /