Sydney Olympic Park Authority has responsibility for the day-to-day and long-term management of ten engineered landfills constructed between 1983 and 2001. These span some 105 hectares and have been rehabilitated and transformed into open space and parklands.
The Sydney Olympic Park Authority is committed to managing remediated landfills and leachate systems to ensure:
The decomposition of waste produces leachate which must be contained and treated without risk to people or the environment. The leachate transfer system consists of over 12 kilometres of rising mains, 26 pump pits, 12 treatment ponds, and three storage tanks. Leachate collected in subsurface collection drains gravitates to a pump pit where it is transferred under pressure to a treatment location.
The majority of leachate is treated at a nearby commercial liquid waste treatment plant. Some leachate is treated in constructed evaporation ponds. Leachate from the site of a former gas works facility at Wilson Park is treated in bioremediation ponds where bacteria degrade hydrocarbons to water and carbon dioxide.
See Environment Reports for more information on the bioremediation system at Wilson Park.
Legal and illegal landfilling operations occurred over several decades on lands that are now within Sydney Olympic Park. The majority of landfilling operations were broadacre fill, and few if any environmental controls were applied.
In a site-wide study conducted in 1991, boreholes were installed on a 50m grid across the site, generally to a depth of 1.6m. Soil and groundwater samples were collected for laboratory analysis to determine the locations and nature of wastes; further investigations were conducted where indicated. Approximately 160-hectares of the site was identified as containing wastes including:
Between 1992 and 2000, the NSW Government allocated $137 million for remedial action to clean up polluted areas. Remedial action varied according to the type and location of the waste and local hydrogeological conditions. It included the recovery, consolidation and on-site containment of approximately nine million cubic metres of waste.
Arising from the extensive clean up program was a quantity of excavated soil contaminated with scheduled chemical waste, which underwent a specialised treatment procedure.
Following remediation, the landfills were certified as suitable for particular land uses by an accredited site auditor (as established by the NSW Contaminated Lands Management Act 1997).
This remediation project was the largest of its kind in Australia and represents a significant environmental achievement and legacy for the people of NSW.
More on the history of landfilling and remediation
Several areas of the parklands were found to contain naturally formed acid sulphate soils (mainly located in or adjacent to estuarine areas such as the Parramatta River and Haslams Creek). When naturally occurring sulphides (from acid sulphate soils) are disturbed and exposed to air, oxidation occurs and sulphuric acid is ultimately produced. This sulphuric acid can drain into waterways and have severe detrimental environmental effects.
Where acid sulphate soils were excavated, these soils were transported, consolidated in deep pits or used as landfill mounds and covered in a manner designed to avoid acid leaching into local waterways and polluting the environment.
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