|Our Environment: Issue 20 Spring 1999|
Search for a New Landfill Site
Canterbury's only major landfill, at Burwood, is set to close in 2002 when its current resource consents expire. Finding a new site for the 300,000 tonnes of commercial and domestic waste generated in the region has emerged as a major challenge for local authorities, including Christchurch City Council.
City efforts aimed at reducing the amount of waste needing to be landfilled have been very successful. In 1994 the amount of waste produced per person per year was 810 kilograms but the 1999 figure is expected to be 680 kilograms. Even so, Christchurch alone generates around 240,000 tonnes of industrial, commercial and domestic rubbish, which ends up in the landfill.
A decision on the preferred site is expected to be reached in October this year. The period of community consultation and detailed investigation may then take another 12 months before a final decision on whether to proceed with the site can be made,and resource consents can be considered.
A joint venture company was formed to establish and operate a new regional landfill. Transwaste Canterbury comprises Canterbury Waste Services Ltd (Waste Management New Zealand and EnviroWaste Services Ltd) and the Canterbury Waste Sub-Committee, including landfill participants representing Christchurch, Waimakariri, Banks Peninsula, Hurunui, Selwyn and Ashburton Councils.
Canterbury councils will be able to close existing landfills in the region and replace them with one regional landfill. Thirty have already been closed. Considerable research and effort is going into the selection of the new landfill to ensure that it will be designed, built and operated in accordance with latest landfill technology and engineering practices.
Those involved in its design will also take into account current international standards and regulations.
The new Canterbury regional landfill must be:
Modern landfills are lined to contain the waste and capped to manage rainwater infiltration and gas emissions. Extensive monitoring systems are put in place to ensure that the landfill operates as designed. Old style dumps or rubbish tips with associated vermin, mud, dust, smells and high contamination risks are no longer permitted.
Before deciding on the landfill option, the Canterbury Waste Joint Standing Committee also looked at incineration, bio-digestion, and neutralysis.
Incineration involves burning the waste. This method is used mostly in Europe and some parts of North America and Asia, where land for landfilling is scarce and costly. New air pollution standards make incineration plants expensive to build and operate. The cost for Canterbury of a suitable plant would be substantially higher. Incineration produces significant amounts of toxic ash and a landfill of even higher standard is still needed to dispose of this. Incineration also works against the success of waste reduction programmes, including recycling, because the plant needs high waste volumes to operate most effectively - the "need to feed the beast" syndrome.
Bio-digestion involves breaking down the organic waste without oxygen, but like composting it still leaves 40 per cent of the waste stream that is inorganic waste needing disposal.
The costs of building and running such a plant would be similar to that of incineration.
Neutralysis is a process which involves burning the waste with clay to produce a building material and generate electricity. It appears that initial trials have not been successful.
The Canterbury Waste Joint Standing Committee concluded that, for this region, controlled landfilling is by far the most cost-effective and environmentally responsible way of disposing of waste, especially as all other methods have leftovers which need a landfill anyway. An extensive public consultation exercise on waste disposal options for Canterbury in early 1997 also supported a controlled landfill.
Guiding principles were developed to help find the most suitable landfill site. These are based on criteria currently being used throughout New Zealand and adapted to Canterbury conditions. They concentrate on:
Other considerations include the vicinity of reserves and national parks, soil types and present land uses, planning zones including housing areas, land ownership and availability of sites. Attention must also be given to natural hazards or flood zones, which may threaten the integrity of the site, the local climate (which may impact on how the site is managed), transport distances, site accessibility and leachate collection and disposal.
A new regional landfill for Canterbury is required to deal with the region's solid waste. As the major contributor to this waste stream, Christchurch City Council is committed to a policy of zero waste to landfill by 2020.
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