Both controlled and uncontrolled waste dumping 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 meters 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).
Increase in the area of landfill from the 1930s until 1988
Remediation and renewal of the site occurred from March 1992 (with the first value management meeting) until February 2001 (final validation report from the independent auditor). The initial aims of the remediation were to block the spread of contamination, restore the waterways and provide for the long term social, cultural and sporting requirements of the people of New South Wales (Value Management Assessment 1992). Supplementary environmental aims were added for the Sydney 2000 Olympic "Green Games" bid including requirements for protection of heritage and biodiversity, energy and water conservation, waste management, sustainable planning and construction and improvements to water, air and soil quality (Sydney Olympics 2000 Bid Ltd 1993). A financial aim was included to ensure an adequate return from the residential and commercial development.
A range of solutions to address the land degradation and contamination were assessed and employed, and other actions were taken to apply ecological sustainability principles, including:
An estimated $137 million was spent on remediation (working out at over AU$180,000 per hectare and much less than the initial $190 million estimated). The remediation resulted in extensive parklands providing recreational opportunities and conservation areas, rejuvenated waterways, world-class recreation and entertainment venues plus residential and commercial districts. Some of the savings were also spent on an "Enhanced Remediation Strategy" which was set up to address community concerns about perceived risks and long-term management of the site after the Games. Read more about the Enhanced Remediation Strategy
The area had been identified for urban renewal in the 1970s and placed on a government priority list for remediation in 1991, due to its central location, proximity to transport routes and the size. In 1992 the NSW Government proposed a remediation strategy for the Homebush Bay area and studies commenced to assess the extent of contamination and determine remediation requirements.
The strategy, which evolved over the next 8 years, addressed all known areas of waste dumping and contaminated sections. Throughout the remediation, adjustments were made to take new information and proposed uses into account. Winning the right to host the 2000 Olympic and Paralympic Games was seen as a suitable end-use rather than the main driver of remediation, although the inflexible time frame and public profile did provide impetus, funding opportunities and innovation.
Solutions to manage the waste and restore the site to beneficial use were defined by:
After consultation on possible site remediation options, the community indicated its preference for the treatment and containment of waste on-site rather than removal to other areas for others to deal with. The strategy chosen to prevent potential health impacts was "consolidate, contain and cap" plus further treatment of some waste.
Waste was consolidated into a number of mounds on-site, then capped with compacted clay and topsoil and a contaminated groundwater collection system installed. This consolidation decreased materials costs and made more land available for development.
Further treatment included microbial breakdown (or biodegradation) of petroleum contaminants and thermal desorption plus catalytic conversion for more intractable types of pollutants. The community was continually consulted throughout the project, through newsletters and a community reference group. Read more about HomBERG (the Homebush Bay Environment Reference Group).
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To read a case study on the Bioremediation at Wilson Park, enter into the Sticky Wicket at Wilson Park.
A risk-based approach was used to minimise exposure rather than remove the hazard from the site. Exposure pathways were identified and types of media treated as follows:
This process allowed for the redirection of leachate and minimised risks to air, soil and water quality. Eleven engineered waste mounds now exist at Sydney Olympic Park (with the inclusion of 2 mounds from Bicentennial Park in 2001). All include leachate management systems to catch and control groundwater flowing through the landfill and the leachate generated from rubbish decomposition. The integrity of the system and the quality of the collected leachate are monitored to ensure the system remains functional and can be managed effectively.
Rehabilitation of the Homebush Bay environment has been a gradual process but there are clear results obtained from the research and monitoring programs:
Open space is now available for increasing public use, including recreation, education and cultural use.
Other benefits identified included the mainstreaming of many "sustainable" activities, skills and education were upgraded and professional standards and practices improved, clean-up legislation was developed and more than 10,000 jobs were created in the area. The cleanup also snowballed remediation and development in nearby areas, as desirability for living in and visiting the district increased.
The remediation and redevelopment provided a lasting legacy from degraded land at a cost far less than initially estimated, due to the risk-based approach and innovative methods used. The integration of consideration of the natural environment into the process resulted in a product of far greater value than originally envisaged.
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