US experience: "Lakes can be used to capture stormwater, as demonstrated in Canberra. Large quantities of water can be stored underground. Adelaide uses urban stormwater, where water goes through a holding storage and a constructed wetland before being fed into a brackish aquifer and recovered at drinking-water quality. The holding basin and a cleansing reed-bed reduces nutrient and pollutant loads by up to 90 per cent. Aquifer recovery fields operate at 60 US sites, where it is seen as an effective means of storing large volumes of water at low cost. The success of aquifer storage in Florida has led to 25 new projects.
Preventing saline-intrusion: "… A key aspect of aquifer recharge is to protect the beneficial uses of the ground water. In some cases, stormwater would improve the water quality in aquifers close to the coast of Brisbane where the ground water is brackish and not currently usable. Monitoring at the Port of Brisbane shows ground water is some 2m below the surface at most locations and is in transition from a saline to freshwater system. Injection of fresh water can prevent seawater intrusion into coastal aquifers and still provide a useful urban storage. Generally before injection into an aquifer, stormwater will need to be cleansed in sediment basins, reedy wetlands or by using sand filters.
Can be used directly: "When extracted it may be possible to be used directly for parks and golf courses. But for human consumption, reverse osmosis is likely to be used to remove heavy metals and other contaminants. Capturing stormwater will reduce the pollution of Brisbane’s creeks and could avoid the environmental impacts of building dams," Wylie added.
Reference: Dr Peter Wylie is a researcher and consultant, specialising in environmental issues, including water, energy, climate change and sustainable farming. He can be reached at peter@horizonrural.com.au
The Courier Mail, 3/11/2007, p. 55