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K3 Results: 21–27 November 2007

K3.1 General waste

K3.1.1 Primary composition of general waste

The primary composition of the general waste is presented in Table K3.1 and Figure K3.1. The secondary composition, which includes all 22 categories, is given in Appendix K6.

Table K3.1: Primary composition of general waste, 21–27 November 2007

Primary category % of total
(
±95% confidence level)
Tonnes/week
Paper 10.4 (±2.7) 1.9
Plastics 15.4 (±4.0) 2.9
Putrescibles 24.8 (±5.9) 4.6
Ferrous metals 5.0 (±1.5) 0.9
Non-ferrous metals 0.8 (±0.2) 0.2
Glass 6.1 (±1.9) 1.1
Textiles 6.3 (±2.1) 1.2
Nappies and sanitary 8.5 (±1.6) 1.6
Rubble 8.9 (±3.7) 1.7
Timber 10.8 (±3.9) 2.0
Rubber 1.1 (±0.5) 0.2
Potentially hazardous 1.7 (±0.8) 0.3
Total 100   18.7

Figure K3.1: Primary composition of general waste, 21–27 November 2007

Putrescible material was the largest single component of the general waste, comprising 25 per cent of the total. Two-thirds of the putrescible material was food waste from both households and businesses. Plastics was the second largest component, with 15 per cent of the total.

K3.1.2 General waste, by activity source

The general waste being disposed of at Kaikoura Landfill comprises all waste other than kerbside collections and loads of glass collected by Innovative Waste Kaikoura and disposed of to landfill. During the survey period, data was gathered on 239 loads of general waste. This included waste from C&D, ICI, landscaping and earthworks, and residential activity. 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 18.7 tonnes of general waste were disposed of at the facility. Determining the actual weight to landfill was problematic because some vehicles disposed of recoverable materials at the separate drop-off points after the vehicle had been weighed and before disposing of the residual waste at the tipping floor. In these instances the surveyor’s estimate of the load weight was used and the weighbridge records adjusted accordingly. A further complication was that some vehicles classified as ‘green waste’ at the weighbridge also disposed of residual waste at the tipping floor. Vehicles classified at the weighbridge as ‘green waste’ were not included in the total for general waste.

Table K3.2 shows the percentage of loads originating from each activity, the percentage of total weight, and the tonnes per week.

Table K3.2: Activity source of general waste, 21–27 November 2007

Activity source No. of loads surveyed % of loads % of total weight Tonnes/week
Construction and demolition 11 4.6 10.4 1.9
Industrial/commercial/institutional 81 33.9 60.9 11.4
Landscaping and earthworks 4 1.7 2.3 0.4
Residential 143 59.8 26.4 4.9
Total 239 100 100 18.7

Residential activity was the source of 60 per cent of all loads of waste, but these loads accounted for only one-quarter 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. About a third of all loads were generated by ICI activity, and these loads accounted for 61 per cent of the total weight. C&D loads, while representing only 5 per cent of all general waste loads, accounted for 10 per cent of the total weight. Waste from landscaping activity generated 2 per cent of loads and 2 per cent of the total weight.

K3.1.3 Primary composition of general waste, by activity source

The primary composition of the four activity sources of general waste is shown in Table K3.3. The secondary composition is given in Appendix K7.

Table K3.3: Primary composition of general waste, by activity source, 21–27 November 2007

Primary category C&D
%
ICI
%
Landscaping
%
Residential
%
Paper 2.8 11.3 1.6 12.1
Plastics 5.5 16.8 1.5 17.4
Putrescibles 5.0 25.4 61.7 28.1
Ferrous metals 4.4 5.3 0.1 5.1
Non-ferrous metals 1.0 0.8 0.0 0.8
Glass 4.3 7.2 0.0 4.9
Textiles 3.4 6.5 0.0 7.4
Nappies and sanitary 1.2 10.2 1.6 8.1
Rubble 42.6 4.8 23.7 3.9
Timber 27.0 8.3 9.9 10.2
Rubber 0.8 1.2 0.0 1.1
Potentially hazardous 1.9 2.1 0.0 0.9

Timber and rubble together comprised most of the C&D waste (70 per cent). ICI waste was more heterogeneous, with no single material comprising more than 26 per cent of the total. Food waste was the largest single component of ICI waste, reflecting the relative size of the hospitality industry in the region. Landscaping waste was primarily green waste (62 per cent), with rubble (mainly soil) comprising about 24 per cent. The largest component of residential waste was putrescible material (28 per cent), which included both food waste from domestic bag drop-offs and landscaping waste. Many residential loads carry waste from several activities, so small quantities of landscaping and C&D waste may be present in a load that was classified as being generated by residential activity.

K3.1.4 General waste, by vehicle type

For each vehicle load of waste disposed of on the tipping floor, the vehicle type was recorded. Table K3.4 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 K3.4: General waste, by vehicle type, 21–27 November 2007

Vehicle type No. of loads % of loads % of weight Tonnes/week
Cars 132 55 16 3.0
Compactors 0 0 0 0.0
Front-loader trucks 0 0 0 0.0
Gantry trucks 0 0 0 0.0
Huka trucks 0 0 0 0.0
Other trucks 28 12 29 5.4
Trailers 79 33 55 10.3
Total 239 100 100 18.7

No compactors, front-loader trucks, gantry trucks or huka trucks disposed of general waste during the survey period. Over half of the loads disposed of on the tipping floor were carried by cars, but car loads accounted for only 16 per cent of the total weight. Many of these car loads comprised a small number of domestic rubbish bags. Trailers represented 33 per cent of all vehicle loads, but these loads accounted for over half of the total weight.

K3.1.5 Primary composition of general waste, by vehicle type

The primary composition of loads carried by the three main types of vehicles that disposed of waste is shown in Table K3.5. The secondary composition is shown in Appendix K8.

Table K3.5: Primary composition of general waste, by vehicle type, 21–27 November 2007

Primary category Car
%
Other truck
%
Trailer
%
Paper 13.0 11.2 9.3
Plastics 17.2 15.3 15.0
Putrescibles 37.3 24.9 21.1
Ferrous metals 3.8 6.0 4.9
Non-ferrous metals 0.6 1.0 0.8
Glass 4.6 9.1 5.0
Textiles 6.5 8.2 5.2
Nappies and sanitary 12.4 8.7 7.2
Rubble 1.0 2.9 14.5
Timber 2.1 10.0 13.8
Rubber 0.4 1.3 1.2
Potentially hazardous 1.0 1.3 2.2

K3.2 Overall waste to landfill

K3.2.1 Source of overall waste to landfill

The overall waste stream being disposed of at Kaikoura Landfill comprised the general waste stream, the private kerbside collection, and glass disposed of by Innovative Waste Kaikoura for landfill stabilisation (special waste). The composition of the overall waste stream has been determined by combining information from the weighbridge records for the survey week with the results of the visual survey.

From the survey it was determined that kerbside refuse collections were being disposed of by a single private waste operator. Weighbridge records were used to calculate the weekly tonnage from this operator. The weekly tonnage of general waste was also calculated from the weighbridge records. Because many small vehicle loads were not weighed by the weighbridge, it was necessary to assign average load weight figures for those vehicles. The amount of glass disposed of to landfill was based on the surveyor’s records because most of the glass entering the facility was stockpiled.

Table K3.6: Waste types to landfill, 21–27 November 2007

Waste type % of weight Tonnes/week
General 79 18.7
Kerbside collections 16 3.8
Special 5 1.3
Transfer station 0 0
Total 100 23.7

A total of 24 tonnes of refuse was disposed of during the survey period. This figure does not include loads of green waste, glass or steel that were disposed of at the separate drop-off points. Of the 24 tonnes disposed of during the week, nearly 80 per cent was general waste. The general waste included the drop-off of domestic refuse by many residents.

K3.2.2 Primary composition of overall waste

The primary composition of the overall waste to landfill is calculated by combining the compositions of the three different waste types in the proportions shown in the previous section. The compositions of the three different waste types have been determined as follows:

  • general waste – as determined from survey results and shown in Section K3.1.1

  • kerbside collection – assumed to be the composition given in Appendix K1, which is based on the results of the previous audits of domestic kerbside refuse undertaken by Waste Not Consulting

  • special – the special waste is all recyclable glass.

The primary composition of the overall waste stream is given in Table K3.7 and Figure K3.2. The secondary composition is given in Appendix K9.

Table K3.7: Primary composition of overall waste, 21–27 November 2007

Primary category % of total Tonnes/week
Paper 10.5 2.5
Plastics 14.4 3.4
Putrescibles 27.1 6.4
Ferrous metals 4.4 1.0
Non-ferrous metals 0.7 0.2
Glass 11.2 2.7
Textiles 5.3 1.2
Nappies and sanitary 8.1 1.9
Rubble 7.3 1.7
Timber 8.6 2.0
Rubber 0.9 0.2
Potentially hazardous 1.5 0.4
Total 100 23.7

Figure K3.2: Primary composition of overall waste, 21–27 November 2007

Putrescible material comprised the largest primary classification of the overall waste stream, with over a quarter of the total. A large proportion of the putrescible material was kitchen/food waste in kerbside refuse and ICI refuse. Plastic was the second largest category, comprising 14 per cent of the total.

K3.3 Discussion and analysis

K3.3.1 C&D waste

Loads of waste generated by C&D activity (see Section 2.6 for the taxonomy of C&D waste) were identified during the visual survey of the general waste stream. Kerbside refuse, the other waste stream besides general waste disposed of at the facility, contains negligible quantities of C&D waste. Special waste contains no C&D waste. The quantity of C&D waste in the overall waste stream is calculated in Table K3.8.

Table K3.8: C&D waste, 21–27 November 2007

Total C&D waste in general waste 1.9 tonnes (from Table K3.2)
Overall waste to landfill 23.7 tonnes (from Table K3.6)
C&D waste as proportion of overall waste to landfill 8.0%

Table K3.8 shows that C&D waste comprised 8.0 per cent, by weight, of the overall waste to landfill.

K3.3.2 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 relevant to the waste disposed of during the 21–27 November 2007 survey period are discussed below.

K3.3.2.1 Weather before and during the survey period

The November audit took place during a very dry early summer. The NIWA National Climate Summary for November 2007 states: “November 2007 was extremely dry in many regions, especially in the South Island, with totals of less than 10 mm throughout much of Nelson, Marlborough, and central Otago”. This could have affected waste generation related to gardening and agricultural activity, given that vegetative growth would have been slowed by the conditions.

K3.3.2.2 Tourism and construction activity

Tourism is a major contributor to the Kaikoura economy, and the tourism sector can be expected to be a major waste generator. November is a period of increasing tourism activity, so it can be expected that waste volumes in November will be greater than in winter but less than during the height of the season in summer. Construction activity is generally higher in summer than in winter, but the November audit showed considerably less C&D waste than the previous audit in September. It is possible that construction in Kaikoura is scheduled to occur during the winter months, to avoid disruption during the tourist season.

K3.3.2.3 Individual waste generators

The quantity of waste disposed of at Kaikoura Landfill is sufficiently small for the composition to be changed significantly by the waste disposal behaviour of a single waste generator. The size of the residual waste stream at Kaikoura Landfill means that the composition may vary considerably from week to week, unlike at larger facilities.