Waste generated in the Matamata region is disposed of at both the Matamata Transfer Station and Tirohia Landfill. Research by Waste Not Consulting in 2006 indicated that over 40 per cent of waste generated within the Matamata–Piako District was taken directly to Tirohia Landfill.13 A substantial proportion of this waste was industrial/commercial/institutional (ICI) waste, collected in front-loader trucks, which do not discharge at the transfer stations in the region. The waste being disposed of at Matamata Transfer Station should, therefore, be regarded as a subset of the total waste generated and disposed of from the region, and may not be representative of the total waste stream.
Data from the surveys also indicates that this is not a consistent subset, but can change substantially over short periods of time. Kerbside collections disposed of at Matamata Transfer Station, for example, increased by one-third between the round 1 survey and the round 3 survey: from 45.5 tonnes per week in the August survey to 60.2 tonnes per week in the February survey and 59.1 tonnes in the May survey. In this writer’s opinion it is unlikely that this increase was related to changes in waste generation, but instead is likely to be the result of alterations in waste operators’ disposal patterns. Changes measured in the composition of the overall residual waste disposed of at Matamata Transfer Station should, therefore, be viewed as a result of changes in disposal patterns by commercial waste operators as well as changes in the composition of waste being generated.
The presence of an alternative waste disposal facility, which accepts the majority of commercial waste from the area, potentially makes the general waste stream sampled at the Matamata Transfer Station an unrepresentative sample of the waste from the area. The changing behaviour of operators bringing more kerbside waste could also artificially change the overall residual waste composition. Without a more complete overview of waste disposal from the district, including information on disposal at Tirohia Landfill, the data collected from Matamata Transfer Station may be unsuitable for measuring trends in the composition of waste going to landfill in the region.