"Leaky landfill" the way to go?
Sharon Beder
Citation: This is article was published as Sharon Beder, '"Leaky landfill" the way to go?', Engineers Australia, October 1998, p. 62.
This is a final version submitted for publication. Minor editorial changes may have subsequently been made.
In Australia contaminated land is usually only cleaned up if a use can be found for it that justifies the cost of that clean up. And it is only cleaned up to the extent that the land use warrants. It is for these reasons that the 760ha disused industrial site at Homebush Bay remained undeveloped for many years, despite its prime city location 12 kilometres from the Sydney central business district.
In 1989 government authorities decided that using the Homebush site for Olympic facilities might provide the necessary incentive for cleaning it up. However, for the NSW government, even the chance of winning an Olympic bid could not justify the estimated $190 million to contain and treat much of the waste to make way for Olympic facilities. It sought a cheaper, more modest remediation strategy that could be carried out and in time for the 1993 Olympic bid. In its efforts to win the opportunity to host the 2000 Olympic Games the government has risked the environment and public health without even consulting the public.
The area contained a cocktail of industrial chemicals including heavy metals, asbestos, pesticides and dioxins. Government authorities considered various options for dealing with these wastes. They dismissed segregation and treating of waste materials as too difficult and expensive. A 'Bank Vault' approach -containing the contaminated soil with double liners beneath, soil capping over the top, leachate drains and gas collection and treatment systems-was tried for a badly contaminated embankment where the Olympic swimming facility was to be built.
The third option, which was chosen for the rest of the site, was to consolidate the landfill waste into a few areas on site, but to dispense with the gas collection and treatment systems and the double liners. This option meant that the wastes would continue to leak into underlying ground water but it was cheaper. Also the government believed that the 'leaky landfill' approach would pose less liability problems. A consultant to the government explained their thinking:
the liability associated with deterioration and or failure of 'Bank vault' secure landfill remained constant with time but its probability of occurrence increased with time as the facility aged. By contrast the leaky landfill would over time carry less liability as the quality of leachate eventually improved. Therefore it is an intrinsically more robust or resilient way of limiting risks.
In other words the liability would leak away with the leachate over time rather than be stored up for a possible sudden and more traceable failure in the future.
However, in the reasons given to the public for the leaky landfill option, cost and limitation of liability were not mentioned. The initial public justification was that it was the only feasible option, given the difficulty of treating such a diverse range of chemicals that were present on the site and the dangers involved in moving these toxic wastes off site. The option of a more secure landfill was not discussed outside of consultants' reports.
A second justification was in terms of risk management. Risk management entails reducing risks rather than eliminating hazards. The argument was that a cover of a metre of clean fill over the landfills and the installation of leachate drains would reduce the risk to people and fauna by reducing the pathways by which they could be exposed to the toxic waste. The fill would prevent direct contact with the toxic waste and reduce the likelihood of rainwater penetrating the landfill and washing out the wastes. Leachate drains would catch any wastes leaking directly into the creeks on the site.
The cost of remediation of the Olympic site based on this strategy was $69 million including landscaping and road base preparations, far less than the original estimate of $190 for more comprehensive remediation. It enabled most of the remediation to be completed by 1993, in time for Sydney to win the bid for the 2000 Olympic Games. A similar risk reduction strategy has now been adopted for the rest of the Homebush site where the Olympic village and a Millenium Park are planned. It is also being heralded as the way to deal with other contaminated sites throughout Australia. However one needs to ask, to what extent is long term environmental health being sacrificed to short term economic expediency?