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M4 Results: 12–18 February 2008

M4.1 General waste

M4.1.1 Primary composition of general waste

The primary composition of the general waste is presented in Table M4.1 and Figure M4.1. The secondary composition, which includes all 22 categories, is given in Appendix M10.

Table M4.1: Primary composition of general waste, 12–18 February 2008

Primary category % of total
(± 95% confidence level)
Tonnes/week
Paper 8.4% (±2.2%) 3.2
Plastics 8.7% (±2.3%) 3.3
Putrescibles 5.4% (±1.5%) 2.1
Ferrous metals 11.3% (±4.9%) 4.3
Non-ferrous metals 0.7% (±0.3%) 0.3
Glass 4.7% (±3.7%) 1.8
Textiles 7.3% (±3.5%) 2.8
Nappies and sanitary 1.2% (±0.4%) 0.5
Rubble 25.4% (±13.9%) 9.8
Timber 24.5% (±7.8%) 9.4
Rubber 1.2% (±1.5%) 0.5
Potentially hazardous 1.1% (±0.6%) 0.4
Total 100%   38.4

Figure M4.1: Primary composition of general waste, 12–18 February 2008

Timber and rubble were the largest components of the general waste, both comprising about 25 per cent of the total. These are the major components of construction and demolition waste, which was the largest source of general waste. Ferrous metals and plastics were the third and fourth largest components, respectively.

M4.1.2 General waste, by activity source

For the purpose of this report, general waste represents the waste disposed of at the Matamata Transfer Station that has not come from kerbside collections. Using the activity source categories (as listed in Section 2.4 ), general waste therefore comprises waste from C&D, ICI, landscaping and earthworks, and residential activities. As each load of general waste was disposed of, it was assessed as to which of these activities had resulted in its generation.

From the weighbridge records for the survey week it was estimated that 38.4 tonnes of general waste were disposed of at the facility. Table M4.2 shows the percentage of loads originating from each activity, the percentage of total weight, and the tonnes per week.

Table M4.2: Activity source of general waste, 12–18 February 2008

Activity source No. of loads surveyed % of loads % of total weight Tonnes/week
Construction and demolition 23 12% 38% 14.8
Industrial/commercial/institutional 25 13% 27% 10.3
Landscaping and earthworks 2 1% 1% 0.4
Residential 141 74% 34% 13.1
Total 191 100% 100% 38.4

Residential activity was the source of nearly three-quarters of all loads of waste, but these loads accounted for only one-third of the total weight of general waste. This is due to a large number of residential waste loads being relatively small, such as when bags of domestic refuse are dropped off. C&D loads, while representing only 12 per cent of all general waste loads, accounted for 38 per cent of the total weight. ICI loads comprised 13 per cent of the total number of loads and 27 per cent of the total weight. A substantial proportion of this waste was from the disposal of the contents of a single farm property. Waste from landscaping activity generated 1 per cent of loads and 1 per cent of the total weight.

M4.1.3 Primary composition of general waste, by activity source

The primary composition of the four activity sources of general waste is shown in Table M4.3. The secondary composition is given in Appendix M11.

Table M4.3: Primary composition of general waste, by activity source, 12–18 February 2008

Primary category C&D ICI Landscaping Residential
Paper 4.7% 11.4% 6.3% 10.1%
Plastics 5.7% 9.6% 3.7% 11.5%
Putrescibles 0.8% 3.3% 64.2% 10.7%
Ferrous metals 12.7% 7.6% 6.3% 12.8%
Non-ferrous metals 0.6% 0.7% 0.5% 1.0%
Glass 0.0% 11.5% 1.3% 4.8%
Textiles 3.5% 7.2% 3.3% 11.7%
Nappies and sanitary 0.1% 0.8% 0.5% 2.8%
Rubble 52.9% 11.7% 2.6% 5.8%
Timber 18.3% 34.2% 10.2% 24.3%
Rubber 0.0% 0.9% 0.5% 2.7%
Potentially hazardous 0.7% 0.9% 0.5% 1.8%

C&D waste was primarily (71 per cent) composed of timber and rubble. Timber was the largest single component of ICI waste, largely due to several loads of wooden pallets and farm waste. Landscaping waste was mainly green waste, but the sample was very small, comprising only two loads. The largest component of residential waste was timber, which was 24 per cent of the total.

M4.1.4 General waste, by vehicle type

For each vehicle load of waste disposed of on the tipping floor, the vehicle type was recorded. Table M4.4 shows the percentage of loads transported by each of the vehicle types, the percentage of total weight carried by each vehicle type, and the tonnes per week.

Table M4.4: General waste, by vehicle type, 12–18 February 2008

Vehicle type No. of loads % of loads % of weight Tonnes/week
Cars 87 46% 8% 3.0
Compactors 0 0% 0% 0.0
Front-loader trucks 0 0% 0% 0.0
Gantry trucks 16 8% 50% 19.1
Huka trucks 0 0% 0% 0.0
Other trucks 3 2% 3% 1.3
Trailers 85 45% 39% 15.1
Total 191 100% 100% 38.4

No front-loader trucks or huka trucks disposed of waste during the survey period. All compactor trucks using the facility were transporting kerbside collections, which are not classified as general waste. Nearly half of the loads disposed of at the transfer shed were carried by cars, but car loads accounted for only 8 per cent of the total weight. Many of these car loads comprised a small number of domestic rubbish bags. Although gantry trucks accounted for only 8 per cent of vehicle loads, these loads accounted for 50 per cent of the total weight. Trailers represented 45 per cent of all vehicle loads and accounted for 39 per cent of the total weight.

M4.1.5 Primary composition of general waste, by vehicle type

The primary composition of loads carried by the four main types of vehicles that disposed of waste is shown in Table M4.5. The secondary composition is shown in Appendix M12.

Table M4.5: Primary composition of general waste, by vehicle type, 12–18 February 2008

Primary category Car Gantry truck Other truck Trailer
Paper 14.9% 6.1% 9.5% 9.9%
Plastics 16.7% 7.5% 12.4% 8.3%
Putrescibles 24.3% 0.7% 2.3% 8.0%
Ferrous metals 7.8% 15.6% 4.9% 7.1%
Non-ferrous metals 0.7% 0.8% 0.1% 0.8%
Glass 6.6% 1.8% 53.1% 3.9%
Textiles 4.5% 9.4% 2.9% 5.6%
Nappies and sanitary 7.4% 0.0% 1.7% 1.5%
Rubble 4.3% 36.5% 6.2% 17.1%
Timber 11.6% 18.8% 5.1% 36.0%
Rubber 0.2% 1.8% 0.9% 0.6%
Potentially hazardous 0.8% 1.1% 1.0% 1.2%

M4.2 Overall residual waste

M4.2.1 Source of overall residual waste

Because there was no special waste, or waste from other transfer stations, being disposed of at Matamata Transfer Station, the overall residual waste stream comprised only the general waste stream and kerbside collections. The composition of the overall residual waste stream has been determined by combining information from the weighbridge records for the survey week with the results of the visual survey.

The survey found that kerbside collections were transported to the Matamata Transfer Station by two private waste operators as well as the council contractor. Using the weighbridge records, the tonnages of kerbside collection waste and general waste were calculated, and these are shown in Table M4.6. Because small vehicle loads such as trailers and cars were recorded by the weighbridge but not weighed, it was necessary to use average load weight figures for these vehicles.

Table M4.6: Overall residual waste types, 12–18 February 2008

Waste type % of weight Tonnes/week
General 39.0% 38.4
Kerbside collections 61.0% 60.2
Special 0% 0
Transfer station 0% 0
Total 100% 98.6

A total of 99 tonnes of refuse were disposed of during the survey period. This figure does not include loads of green waste or steel that were disposed of at the separate drop-off points. Of the 99 tonnes disposed of during the week, over 60 per cent was from kerbside collections and the rest was general waste.

M4.2.2 Primary composition of overall residual waste

The primary composition of the overall residual waste stream is calculated by combining the compositions of the two waste types in the proportions shown in the previous section. The compositions of the two waste types have been determined as follows:

  • general waste – as determined from survey results and shown in Section M4.1.1

  • kerbside collection – the assumed composition (see Appendix M1) for the kerbside collection was that determined by the sort-and-weigh audits undertaken at the Matamata Transfer Station in 2003/04 for the Ministry for the Environment SWAP Baseline Data Programme.

The primary composition of the overall residual waste stream is given in Table M4.7 and Figure M4.2. The secondary composition is given in Appendix M13.

Table M4.7: Primary composition of overall residual waste, 12–18 February 2008

Primary category % of total Tonnes/week
Paper 13.9% 13.7
Plastics 12.5% 12.4
Putrescibles 24.0% 23.6
Ferrous metals 7.6% 7.5
Non-ferrous metals 0.8% 0.8
Glass 5.6% 5.5
Textiles 6.1% 6.0
Nappies and sanitary 7.2% 7.1
Rubble 10.5% 10.4
Timber 10.2% 10.1
Rubber 0.6% 0.6
Potentially hazardous 0.9% 0.9
Total 100% 98.6

Figure M4.2: Primary composition of overall residual waste, 12–18 February 2008

Putrescible material comprised the largest primary classification of the overall residual waste stream, with 24 per cent of the total. A large proportion of the putrescible material was kitchen waste in kerbside collections. Paper was the second largest component, comprising 14 per cent of the total. Rubble, timber and plastics comprised similar proportions of the total, from 10 to 13 per cent.

M4.3 Discussion and analysis

M4.3.1 C&D waste

Loads of waste generated by C&D activities (see Section 2.6 for the taxonomy of C&D waste ) were identified during the visual survey of the general waste stream. Kerbside collections, the other waste stream other than general waste disposed of at the facility, contain negligible quantities of C&D waste. The quantity of C&D waste in the overall residual waste stream is calculated in Table M4.8.

Table M4.8: C&D waste, 12–18 February 2008

Total C&D waste in general waste 14.8 tonnes (from Table M4.2)
Overall residual waste 98.6 tonnes (from Table M4.6)
C&D waste as proportion of overall residual waste 15%

Table M4.8 shows that C&D waste comprised 15 per cent, by weight, of the overall residual waste.

M4.3.2 Factors affecting waste generation and disposal during survey period

A range of factors affect the quantity and composition of waste disposed of at any individual disposal facility. Some of the factors considered to be most relevant to the waste disposed of at the transfer station during the 12–18 February 2008 survey period are discussed below.

M4.3.2.1 Weather before and during the survey period

The February audit took place in mid-summer during a period of warm weather with intermittent showery conditions. Overall, however, the region was in the midst of a prolonged drought. The Waikato region was officially declared a drought zone in early February, with the driest January in more than 100 years having been recorded.8

Due to the drought conditions the council had initiated a sprinkler ban in areas using the town water supply.9 Low rainfall and the sprinkler ban would have resulted in below-average vegetative growth and less green waste being generated.

M4.3.2.2 Economic conditions

Economic conditions in Waikato for the December 2007 quarter were generally positive. The National Bank regional trends report was as follows:10

Waikato recorded a 3.4 percent rise in employment in December, taking the annual growth in the 2007 calendar year to 6.4 percent. Both measures were over twice the rate of increase measured nationally. Waikato’s real estate market outperformed the national figures. The number of house sales rose 4.5 percent (up 0.6 percent nationally) and large farm sales rose 9.4 percent (3.2 percent). Lifestyle blocks recorded a small rise, while the amount of sections sold doubled from the number that were sold three months earlier. Building consents were close to the national equivalents, for both residential and commercial projects. Accommodation guest nights dropped 8.2 percent, undershooting the 1.6 percent decline recorded nationally.

Although these factors may have medium- to long-term effects on waste flows, the effects on waste generation and disposal during the survey period can not be estimated.

M4.3.2.3 Changes in kerbside collections

There was a marked increase in the quantity of kerbside collections disposed of during the February survey period. During the August survey period, 45.5 tonnes of kerbside collections were disposed of at the Matamata facility, and in November the total was 51.3 tonnes. In February, however, analysis of the weighbridge records indicates that 60.2 tonnes of kerbside collections were disposed of. Most of the increase was from private waste operators, with the council kerbside collection making up 14.2 tonnes in November and 14.9 tonnes in February.

It is the opinion of this writer that the increase in the tonnage of kerbside collections is more likely to have been due to a change in waste operators’ disposal patterns than to a substantial increase in the overall tonnage of kerbside collections throughout the district. It is possible, for instance, that a private waste operator who previously disposed of waste at another disposal facility, such as Tokoroa Landfill or Tirohia Landfill, is now disposing of that waste at Matamata Transfer Station. Without further evidence, no assumptions can be made about the cause of the increase in the tonnage of kerbside collections.

M4.3.2.4 Individual waste generators

The quantity of waste disposed of at the Matamata Transfer Station is sufficiently small for the composition to be changed significantly by the waste disposal behaviour of a single waste generator. This was shown in the February audit by the disposal of waste from a single farm property representing a substantial portion of the ICI waste during the survey.