Why did these audits use a visual survey measurement when the Ministry for the Environment’s Solid Waste Analysis Protocol (SWAP) recommends the sort-and-weigh method?
It is for health and safety reasons that Waste Not Consulting (WNC) does not use sort-and-weigh measurement for waste audits at disposal facilities. WNC considers that the risks from physically handling the waste or risks from the waste materials can not be reasonably mitigated.
WNC also favours visual surveys for other practical reasons. Visual surveys allow for more vehicles to be sampled at a lower cost. WNC has not found a satisfactory and practical method for obtaining random sub-samples of loads of waste for sorting and weighing.
Why does this audit suggest that some of the sites may not be representative of waste disposed of in their entire regions?
The audit notes that without further research, the representativeness of the site-specific data for their region cannot be determined. The high cost of collecting waste composition information impedes expansion of the programme to either more frequent sampling or to coverage of more sites at present.
The SWAP Data Programme focuses on collecting generic waste composition data for New Zealand. These sample sites were selected to reflect urban and rural waste in the North and South Islands. Combining the results from all four sites may be representative at a national scale.
Why continue sampling these sites if they may not be representative of waste disposed of in their entire regions?
The selected sites were initially sampled in 2003/04. The same sites were re-sampled in 2007/08 to provide a long-term data set, which will enable the detection of any trends over time.
How is the Ministry going to improve the collection of national-scale waste composition data?
The Waste Minimisation Act 2008 provides the opportunity to collect national information on waste. The Ministry is working to develop a waste composition data collection programme that will more frequently collect data at more landfills in the future.[ Next ]