Sydney's attention has recently focused on the UNSW Village Green where stormwater is now being harvested to recharge and balance groundwater supplies. This stormwater diversion and reuse project was initiated byUNSW Facilities personnel as part of consent conditions for development on campus. The new system directs runoff from 65% of the campus through gross pollutant traps to a large Atlantis Infiltration Tank buried below the sports ground. The chambers were designed to reconnect up to 160 ML/year of runoff, the equivalent of 64Olympic swimming pools, from impermeable surfaces on the campus to natural underground storage in theBotany sand aquifer.As well as replenishing the aquifer, which is used as an additional water supply by local residents and industry, the pit takes some pressure off Kensington’s storm water pipes by channeling the water into the aquifer rather than the sewage system.
Sampling from the piezometers showed that the groundwater quality differs with varying depth in the aquifer.Nitrate levels, pH and thermo tolerant coliform levels were some indicators which varied with depth. In addition, groundwater quality was found to vary at different monitoring bores around the campus.Ongoing monitoring of percolation chamber water levels, in addition to long-term rainfall monitoring, are essential requirements in determining the volume of additional water that is harvested and recharged. However, the volume of additional groundwater supply that can be generated for campus use is likely to be less than the stormwater added to the system, due to slow groundwater flow to the southwest away from the campus.