Waste dumping, controlled and uncontrolled, around Homebush Bay transformed the once bountiful wetlands into ugly tips and polluted waterways. Sydney's rapid expansion in the 1950s and 60s and the start of the "throw-away" society meant people and industry needed more space to put their waste. By 1970 Wentworth Bay no longer existed and by 1978 most low-lying land had been filled.
By 1988 there was an estimated 9 million cubic metres of waste and contaminated soils spread over 400 hectares within the 760 hectare site. The waste was not homogenous and included petroleum waste, unexploded ordnance, potential acid suphate soils, illegally dumped wastes along the waterways (including persistent organic pollutants, Polycyclic aromatic hydrocarbons, etc), dredged sediments, municipal waste in managed tips, industrial waste (including rubble, power station fly ash, gasworks waste, asbestos) and contamination from site activities (burning pits, chemical leaks and application).
The remediation of past domestic, commercial and industrial waste sites at Sydney Olympic Park was the largest project of its kind in Australia and is one of the most significant environmental legacies of the Sydney 2000 Olympic and Paralympic Games
Controlled and uncontrolled 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 power station ash, demolition rubble, asbestos, industrial hydrocarbons, domestic garbage, and dredging material from the Parramatta River
Between 1992 and 2000, the NSW Government allocated $137 million for remedial action to clean up polluted areas. The remediation policy at the time was to safely contain and where possible treat, waste on site, rather than relocating it to other places.
Many investigations were done prior to the commencement of works. Pollution profiles of various areas were established and groundwater and soil investigations undertaken, as well as studies of the natural environment.
Remedial action varied according to the type and location of the waste and local hydrological and soil conditions, and included the recovery, consolidation and containment of about 9 million cubic metres of waste. Approximately 400 tonnes of soil contaminated with hydrocarbons and classified under environmental legislation as ‘scheduled chemical waste’ was treated in a two-stage thermal desorption process. The majority of the buried waste was removed and relocated to designated waste containment mounds. These areas were capped, landscaped and turned into parkland. Leachate collection and transfer systems were built to prevent leachate from escaping into the environment.
The remediation works were regulated by the Environment Protection Authority, and subject to stringent conditions directed at ensuring environmental protection and public safety. Following remediation, the landfills were certified as suitable for use as parks and recreational open space by an accredited site auditor, in accordance with regulatory requirements.