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M5 Results: 5–11 May 2008

M5.1 General waste

M5.1.1 Primary composition of general waste

The primary composition of the general waste is presented in Table M5.1 and Figure M5.1. The secondary composition, which includes all 22 categories, is given in Appendix M14.

Table M5.1: Primary composition of general waste, 5–11 May 2008

Primary category % of total
(± 95% confidence level)
Tonnes/week
Paper 8.8% (±6.2%) 3.6
Plastics 12.1% (±9.3%) 5.0
Putrescibles 15.5% (±14.5%) 6.4
Ferrous metals 5.4% (±3.0%) 2.2
Non-ferrous metals 0.5% (±0.4%) 0.2
Glass 2.9% (±1.7%) 1.2
Textiles 3.6% (±2.1%) 1.5
Nappies and sanitary 0.6% (±0.1%) 0.3
Rubble 32.6% (±25.3%) 13.4
Timber 17.2% (±8.7%) 7.1
Rubber 0.4% (±0.3%) 0.2
Potentially hazardous 0.4% (±0.2%) 0.2
Total 100%   41.2

Figure M5.1: Primary composition of general waste, 5–11 May 2008

Timber and rubble were the largest components of the general waste, with rubble comprising about 33 per cent of the total and timber 17 per cent. Timber and rubble are the major components of construction and demolition waste, which was the largest activity source of general waste. Putrescibles and plastics were the third and fourth largest components, respectively.

M5.1.2 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 41.2 tonnes of general waste were disposed of at the facility. Table M5.2 shows the percentage of loads originating from each activity, the percentage of total weight, and the tonnes per week.

Table M5.2: Activity source of general waste, 5–11 May 2008

Activity source No. of loads surveyed % of loads % of total weight Tonnes/week
Construction and demolition 14 7% 49% 20.1
Industrial/commercial/institutional 29 15% 29% 11.8
Landscaping and earthworks 11 6% 2% 1.0
Residential 141 72% 20% 8.3
Total 195 100% 100% 41.2

Residential activity was the source of nearly three-quarters of all loads of waste, but these loads accounted for only 20 per cent 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 7 per cent of all general waste loads, accounted for nearly half of the total weight. ICI loads comprised 15 per cent of the total number of loads and 29 per cent of the total weight. Waste from landscaping activity generated 6 per cent of loads and 2 per cent of the total weight.

M5.1.3 Primary composition of general waste, by activity source

The primary composition of the four activity sources of general waste is shown in Table M5.3. The secondary composition is given in Appendix M15.

Table M5.3: Primary composition of general waste, by activity source, 5–11 May 2008

Primary category C&D ICI Landscaping Residential
Paper 2.9% 19.0% 0.5% 9.4%
Plastics 5.0% 26.7% 0.4% 9.9%
Putrescibles 1.5% 30.6% 85.0% 19.3%
Ferrous metals 3.5% 3.3% 0.1% 13.6%
Non-ferrous metals 0.2% 1.0% 0.0% 0.7%
Glass 1.5% 5.3% 0.2% 3.5%
Textiles 2.4% 0.8% 0.1% 10.9%
Nappies and sanitary 0.0% 0.2% 0.3% 2.7%
Rubble 59.1% 5.6% 0.7% 10.9%
Timber 23.2% 7.2% 12.7% 17.5%
Rubber 0.4% 0.1% 0.0% 0.9%
Potentially hazardous 0.3% 0.3% 0.0% 0.8%

C&D waste was primarily (82 per cent) composed of timber and rubble. Several gantry truck loads of C&D waste contained large amounts of concrete. ICI waste contained similar amounts of putrescible material and plastics (31 per cent and 27 per cent respectively). A substantial proportion of the putrescible material was poultry feed dumped as a result of flood damage, and a high proportion of the plastics waste was transported in a single vehicle load. Landscaping waste was primarily green waste. The largest component of residential waste was putrescible material, which comprised 19 per cent of the total. The putrescible material included both green waste and food waste in bagged refuse.

M5.1.4 General waste, by vehicle type

For each vehicle load of waste disposed of on the tipping floor, the vehicle type was recorded. Table M5.4 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 M5.4: General waste, by vehicle type, 5–11 May 2008

Vehicle type No. of loads % of loads % of weight Tonnes/week
Cars 121 62% 11% 4.5
Compactors 0 0% 0% 0.0
Front-loader trucks 0 0% 0% 0.0
Gantry trucks 14 7% 61% 25.0
Huka trucks 0 0% 0% 0.0
Other trucks 13 7% 13% 5.3
Trailers 47 24% 16% 6.4
Total 195 100% 100% 41.2

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. Over 60 per cent of the loads disposed of at the transfer shed were carried by cars, but car loads accounted for only 11 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 7 per cent of vehicle loads, these loads accounted for 61 per cent of the total weight. Trailers represented 24 per cent of all vehicle loads and accounted for 16 per cent of the total weight.

M5.1.5 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 M5.5. The secondary composition is shown in Appendix M16.

Table M5.5: Primary composition of general waste, by vehicle type, 5–11 May 2008

Primary category Car Gantry truck Other truck Trailer
Paper 11.8% 2.7% 35.0% 8.3%
Plastics 14.5% 4.6% 42.4% 14.8%
Putrescibles 19.1% 14.1% 3.9% 27.7%
Ferrous metals 10.3% 4.7% 2.5% 6.6%
Non-ferrous metals 0.5% 0.2% 2.0% 0.5%
Glass 3.1% 1.5% 2.6% 8.7%
Textiles 9.5% 3.0% 0.6% 4.3%
Nappies and sanitary 4.1% 0.0% 0.4% 0.6%
Rubble 10.9% 48.2% 0.4% 14.2%
Timber 14.8% 20.3% 9.6% 13.0%
Rubber 0.3% 0.4% 0.1% 0.7%
Potentially hazardous 0.9% 0.3% 0.4% 0.5%

M5.2 Overall residual waste

M5.2.1 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 being disposed of by two private waste operators as well as the council contractor. From the weighbridge records it was calculated that the tonnages of kerbside collections and general waste shown in Table M5.6 were disposed of at the facility.

Table M5.6: Overall residual waste types, 5–11 May 2008

Waste type % of weight Tonnes/week
General 41% 41.2
Kerbside collections 59% 59.1
Special 0% 0
Transfer station 0% 0
Total 100% 100.3

A total of 100 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 100 tonnes disposed of during the week, 59 per cent was from kerbside collections and the rest was general waste.

M5.2.2 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 M5.1.1

  • 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 M5.7 and Figure M5.2. The secondary composition is given in Appendix M17.

Table M5.7: Primary composition of overall residual waste, 5–11 May 2008

Primary category % of total Tonnes/week
Paper 13.9% 13.9
Plastics 13.8% 13.9
Putrescibles 27.5% 27.6
Ferrous metals 5.3% 5.3
Non-ferrous metals 0.7% 0.7
Glass 4.9% 4.9
Textiles 4.6% 4.6
Nappies and sanitary 6.8% 6.8
Rubble 14.0% 14.0
Timber 7.7% 7.7
Rubber 0.3% 0.3
Potentially hazardous 0.6% 0.6
Total 100% 100.3

Figure M5.2: Primary composition of overall residual waste, 5–11 May 2008

Putrescible material comprised the largest primary classification of the overall residual waste stream, with 28 per cent of the total. A large proportion of the putrescible material was kitchen waste in kerbside collections. Paper and plastics were the second largest components, both comprising 14 per cent of the total.

M5.3 Discussion and analysis

M5.3.1 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 M5.8.

Table M5.8: C&D waste, 5–11 May 2008

Total C&D waste in general waste 19.2 tonnes (from Table M5.2)
Overall residual waste 100.3 tonnes (from Table M5.6)
C&D waste as proportion of overall residual waste 19%

Table M5.8 shows that C&D waste comprised 19 per cent, by weight, of the overall residual waste.

M5.3.2 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 at the transfer station during the 5–11 May 2008 survey period are discussed below.

M5.3.2.1 Weather before and during the survey period

The May audit took place during a period of cool weather, with some cloud but no significant rainfall. After drought conditions in the region in January and February, rainfall was very high in April, particularly in the Bay of Plenty and Taupo, where more than double the normal April totals occurred.11 This would have resulted in increased vegetative growth in the month before the audit.

M5.3.2.2 Economic conditions

Economic conditions in the Waikato for the March 2008 quarter were generally less positive than in the previous quarters. The National Bank regional trends report gave the following summary:12

Both business and consumer confidence slumped in March. Business confidence dropped to the lowest level in our survey, no doubt reflecting drought conditions in the region. Some of this pessimism looks to have rubbed off onto households, with consumer confidence dropping to a ten year low. Dwelling approvals eased in line with the national figure, but commercial construction recorded a small rise (up 0.6 percent). Employment dropped 0.7 percent, about half the 1.3 percent fall 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.

M5.3.2.3 Changes in kerbside collections

There was a marked increase in the quantity of kerbside collections disposed of between the November 2007 and February 2008 survey periods. During the August 2007 survey period, 45.5 tonnes of kerbside collections were disposed of at the Matamata facility and in November it was 51.3 tonnes. In February, analysis of the weighbridge records indicated that 60.2 tonnes of kerbside collections were disposed of, and 59.1 tonnes were disposed of during the May 2008 survey. Most of the increase was from private waste operators: the council kerbside collection component comprised 14.2 tonnes in November, 14.9 tonnes in February and 13.7 tonnes in May.

It is the opinion of this writer that the increase in the tonnage of kerbside collections is more likely to be 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.