View all publications

3 SWAP Waste Data Programme 2007/08: Summary of Results

This section presents a summary of the results of the surveys undertaken at all four sites included in the SWAP Waste Data Programme. Results are presented for the:

  • primary composition of the four activity sources that make up the general waste stream at each site (C&D, ICI, landscaping and earthworks, and residential)

  • source and primary composition of the general waste stream at each site

  • source and primary composition of the overall waste stream at each site.

In the analyses of the activity sources and general waste streams, the transfer station and disposal faces at Green Island Landfill and Silverstream Landfill are treated as separate facilities. For the analyses of the overall waste stream, the transfer station and disposal faces are treated as being a combined facility.

3.1 Activity sources

3.1.1 Construction and demolition waste

Figure 3.1 shows the average composition (from the four survey results) of the C&D waste at each of the six facilities surveyed during the 2007/08 programme.

Figure 3.1: Primary composition of C&D waste at all sites
 

 

Primary category Green Island Transfer pit Green Island disposal face Silverstream transfer station Silverstream tip face Matamata Transfer Station Kaikoura Landfill
Paper 3% 0.8% 2% 4% 4% 2%
Plastics 2% 1.2% 3% 4% 5% 5%
Putrescibles 2% 2% 4% 4% 2% 2%
Ferrous metals 4% 3% 4% 6% 9% 3%
Non-ferrous metals 0.2% 0.3% 0.3% 0.2% 0.5% 0.7%
Glass 1.1% 0.2% 1.1% 1.2% 2% 3%
Textiles 3% 1.2% 3% 1.2% 3% 7%
Nappies and sanitary 0.0% 0.0% 0.0% 0.1% 0.0% 0.4%
Rubble 31% 66% 30% 23% 45% 41%
Timber 53% 25% 53% 54% 29% 34%
Rubber 0.2% 0.1% 0.0% 2% 0.3% 2%
Potentially hazardous 0.2% 0.2% 0.3% 0.4% 0.6% 1.4%

At all six sites, rubble and timber together comprised a very large proportion of C&D waste. The proportion of rubble at the six sites had a relatively high variation, ranging from 23 per cent to 66 per cent. At the Green Island disposal face, rubble comprised a larger proportion than at the other sites. This was associated with low gate charges for cleanfill-type materials.

The proportion of timber was higher at three of the six sites − Green Island transfer pit, Silverstream transfer station and Silverstream tip face. This may be the result of more demolition activities taking place in these areas at the time of the surveys compared with construction activities, given that demolishing a structure typically generates more timber waste than construction does.

3.1.2 Industrial/commercial/institutional waste

Figure 3.2 shows the average composition (from the four survey results) of the ICI waste at each of the six facilities surveyed during the 2007/08 programme.

Figure 3.2: Primary composition of ICI waste at all sites

 

Primary category Green Island transfer pit Green Island disposal face Silverstream transfer station Silverstream tip face Matamata Transfer Station Kaikoura Landfill
Paper 18% 17% 9% 12% 16% 12%
Plastics 11% 16% 9% 18% 21% 15%
Putrescibles 5% 12% 8% 23% 13% 25%
Ferrous metals 9% 4% 5% 5% 7% 6%
Non-ferrous metals 0.4% 1.0% 1.0% 0.9% 1.0% 0.9%
Glass 8% 17% 5% 9% 8% 8%
Textiles 16% 4% 8% 7% 4% 8%
Nappies and sanitary 1.2% 2% 1.0% 4% 0.8% 10%
Rubble 4% 13% 3% 3% 7% 4%
Timber 24% 10% 14% 14% 21% 8%
Rubber 2% 3% 35% 1.5% 0.5% 1.4%
Potentially hazardous 0.5% 0.7% 1.2% 3% 1.0% 2%

A different primary material constitutes the greatest proportion of waste generated from ICI activities at each of the six sites. The composition of ICI waste is also spread across the full range of material types, with paper, plastics, putrescibles and timber all comprising over 10 per cent of the total waste stream at four of the sites.

The proportion of some of the primary material categories in ICI waste varied considerably between the six sites, while others were relatively consistent. In several instances the variations have been identified as being associated with individual waste generators. For example, the high proportion of plastics at Matamata Transfer Station was associated with waste delivered from an explosives manufacturer, the high proportion of glass at the Green Island disposal face was associated with waste from a recycling processor, and the high proportion of rubber at the Silverstream transfer station was associated with tyre distributors.

3.1.3 Landscaping and earthworks waste

Figure 3.3 shows the average composition (from the four survey results) of the landscaping and earthworks waste at each of the six facilities surveyed during the 2007/08 programme.

Figure 3.3: Primary composition of landscaping and earthworks waste at all sites

Primary category Green Island transfer pit Green Island disposal face Silverstream transfer station Silverstream tip face Matamata Transfer Station Kaikoura Landfill
Paper 2% 0.2% 0.5% 1.0% 3% 0.5%
Plastics 2% 0.3% 0.6% 0.9% 2% 1.2%
Putrescibles 53% 33% 83% 72% 62% 59%
Ferrous metals 1.2% 0.3% 1% 0.8% 2% 0.8%
Non-ferrous metals 0.1% 0.0% 0.0% 0.0% 0.1% 0.0%
Glass 0.8% 1.2% 0.2% 0.1% 1.1% 0.1%
Textiles 0.8% 0.1% 0.5% 0.4% 0.9% 0.3%
Nappies and sanitary 0.3% 0.0% 0.1% 0.1% 0.4% 0.5%
Rubble 32% 64% 12% 19% 20% 31%
Timber 7% 1.3% 3% 4% 9% 7%
Rubber 0.7% 0.0% 0.1% 1.1% 0.1% 0.0%
Potentially hazardous 0.1% 0.0% 0.1% 0.0% 0.1% 0.0%

At all six sites, landscaping and earthworks waste is composed almost entirely of putrescibles (mainly green waste, ranging between 33 and 83 per cent) and rubble (mainly soil, ranging between 12 and 64 per cent), with minor quantities of timber (under 10 per cent). The high proportion of green waste at Silverstream transfer station was associated with all of the green waste being disposed of directly to landfill, whereas green waste is diverted from landfill disposal at all of the other sites. The high proportion of rubble at Green Island disposal face was associated with low disposal charges for cover materials.

3.1.4 Residential waste

Figure 3.4 shows the average composition (from the four survey results) of the residential waste at each of the six facilities surveyed during the 2007/08 programme.

Figure 3.4: Primary composition of residential waste at all sites

 

Primary category Green Island transfer pit Green Island disposal face Silverstream transfer station Silverstream tip face Matamata Transfer Station Kaikoura Landfill
Paper 10% 5% 9% 7% 10% 12%
Plastics 8% 4% 10% 11% 11% 15%
Putrescibles 11% 18% 21% 12% 13% 26%
Ferrous metals 12% 14% 12% 18% 13% 7%
Non-ferrous metals 0.7% 0.7% 0.6% 0.8% 0.9% 1.1%
Glass 5% 2% 3% 4% 4% 6%
Textiles 18% 12% 10% 12% 9% 9%
Nappies and sanitary 1.3% 0.1% 2% 0.4% 2% 9%
Rubble 5% 11% 5% 8% 9% 4%
Timber 27% 33% 25% 27% 24% 10%
Rubber 1.2% 0.9% 0.9% 0.8% 1.2% 1.0%
Potentially hazardous 0.6% 0.7% 0.7% 1.1% 1.2% 1.2%

With a few exceptions there is a fair degree of consistency in the composition of residential waste at all six sites. Timber constitutes the largest proportion (ranging between 9 and 33 per cent) at all the sites except the Kaikoura Landfill. Paper, plastics, putrescibles, ferrous metals and textiles make up other major components at all sites.

The composition of residential waste at Kaikoura Landfill was somewhat different to the other sites because a higher proportion of the residential waste was domestic bagged refuse. For example, the proportions of putrescibles and nappies and sanitary waste are significantly higher than at the other sites, because the residential waste contained more domestic bagged refuse. At all the other sites, domestic bagged refuse was only a small proportion of the residential waste, because most is collected by a council kerbside collection and therefore classified separately as kerbside collection waste. There is no council kerbside collection in Kaikoura, and the private kerbside collection is relatively small, and so domestic bagged refuse dropped off by householders is a much higher proportion of residential waste.

3.2 General waste

3.2.1 General waste, by activity source

Figures 3.5 and 3.6 show the activity source of the general waste stream at the six sites surveyed.

Figure 3.5: Activity source of general waste stream, by type

 

Primary category Green Island transfer pit Green Island disposal face Silverstream transfer station Silverstream tip face Matamata Transfer Station Kaikoura Landfill
Construction and Demolition 27% 27% 14% 8% 49% 12%
Industrial/Commercial/ Institutional 16% 25% 9% 83% 21% 54%
Landscaping and Earthworks 10% 43% 39% 4% 3% 6%
Residential 48% 6% 37% 4% 27% 28%

Figure 3.6: Activity source percentage of total general waste stream by site

 

Primary category Green Island transfer pit Green Island disposal face Silverstream transfer station Silverstream tip face Matamata Transfer Station Kaikoura Landfill
Construction and Demolition 27% 27% 14% 8% 49% 12%
Industrial/Commercial/ Institutional 16% 25% 9% 83% 21% 54%
Landscaping and Earthworks 10% 43% 39% 4% 3% 6%
Residential 48% 6% 37% 4% 27% 28%

Each facility exhibits a distinct pattern to the proportions of the different activity sources making up the general waste stream. At Green Island much of the residential waste was disposed of by householders at the transfer pit, with a smaller amount being disposed of (generally by gantry truck) directly to the disposal face. There are separate green waste and cleanfill drop-off points at the Green Island Resource Recovery Area, so only a relatively small proportion of the residual waste was landscaping and earthworks waste. Conversely, at the Green Island disposal face there was a high proportion of landscaping and earthworks waste, which was associated with a lower gate charge for cover materials such as soil. ICI waste and C&D waste comprised similar proportions of the general waste at the transfer pit and disposal face.

ICI waste was the largest single source of waste at the Kaikoura Landfill, comprising over 50 per cent of the total, with residential waste making up over a quarter. A substantial proportion of the residential waste comprised domestic refuse bags dropped off by householders.

At Matamata Transfer Station C&D activity was the largest source of general waste, at nearly 50 per cent of the total. The proportion of ICI waste was relatively low because a substantial amount of ICI waste from the town is taken directly to landfill by commercial waste operators and does not pass through the transfer station. Most green waste entering the facility is discharged at the separate drop-off point, resulting in a low proportion of landscaping waste in the general waste.

At the Silverstream transfer station green waste from the separate drop-off point is disposed of to landfill, resulting in a high proportion of landscaping waste in the general waste. The proportion of ICI waste is low because most ICI waste is taken directly to the tip face by commercial waste operators. ICI waste represented most of the general waste discharged at the Silverstream tip face. There is not a reduced gate charge for cleanfill-type materials at Silverstream, so most waste of this kind are likely to be disposed of at cleanfill sites rather than at the landfill.

3.2.2 Primary composition of general waste

The average general waste composition at each of the six sites is shown in Figure 3.7. This composition does not include waste from kerbside collections or special waste. The average for each facility has been calculated by totalling the tonnages of the primary classifications of general waste from each of the four surveys at each site and dividing by four.

Figure 3.7: Composition of general waste

 

Primary category Green Island transfer pit Green Island disposal face Silverstream transfer station Silverstream tip face Matamata Transfer Station Kaikoura Landfill
Paper 9% 5% 5% 11% 8% 10%
Plastics 6% 5% 5% 16% 10% 13%
Putrescibles 12% 14% 42% 23% 10% 26%
Ferrous metals 8% 3% 6% 6% 9% 5%
Non-ferrous metals 0.5% 0.4% 0.3% 0.7% 0.7% 1.0%
Glass 4% 5% 2% 8% 4% 6%
Textiles 12% 2% 5% 6% 5% 7%
Nappies and sanitary 0.7% 0.5% 0.9% 3% 0.8% 8%
Rubble 14% 54% 11% 5% 26% 9%
Timber 32% 11% 19% 17% 25% 11%
Rubber 1.1% 0.8% 3% 1.5% 0.7% 1.1%
Potentially hazardous 0.5% 0.2% 0.4% 2% 0.8% 1.4%

For most of the primary materials there is a reasonable degree of consistency between the results from the six sites. The inconsistent results are in most cases related to specific waste generators or identified factors at the facility. Putrescibles at Silverstream transfer station, for instance, represented a markedly greater proportion of the general waste because green waste is disposed of directly to landfill at that facility. Glass was a higher proportion of general waste at Kaikoura because, although it was collected separately, all glass was landfilled.

The proportion of nappies/sanitary waste at the Kaikoura Landfill is significantly higher compared to the other sites. This is considered to be due to the large number of domestic rubbish bags included in the residential waste stream, which is not the case at the other sites. The proportion of rubble in the general waste stream at Green Island disposal face is significantly higher than at all the other sites, and is considered to be due to the large quantities of cleanfill waste disposed at the site when there was no gate charge.

3.3 Overall waste to landfill

3.3.1 Source of overall waste, average over surveys

The averages of the different waste streams received from the four surveys at each site are shown in Figure 3.8.

Figure 3.8: Average activity source of overall waste

Primary category Green Island Landfill Silverstream Landfill Matamata Transfer Station Kaikoura Landfill
Cover Material 54% 4% 0% 0%
General Waste 23% 28% 44% 73%
Kerbside Collections 6% 14% 56% 15%
Special Waste 11% 39% 0% 12%
Transfer Station 7% 15% 0% 0%

The proportions of the different waste streams that make up the overall waste sent to landfill at each site are markedly different. Over 70 per cent of the waste discharged at Kaikoura Landfill is general waste, with kerbside collections and special waste (glass) comprising equal proportions of the remainder. At Matamata Transfer Station, over half of the waste stream is from kerbside collections, with all of the remainder being general waste (ie, there was no special waste, cover material, or other transfer station waste disposed of at this site). At Green Island Landfill cover material comprised, on average, over half of the overall waste stream, which is associated with there being no gate charge for cover material during the first two surveys. Special waste (predominately contaminated soil from a research facility) was the largest component of the overall waste at Silverstream Landfill, with 39 per cent of the total.

3.3.2 Source of overall waste, by survey

Figure 3.8 shows the average proportion of each activity source at each site from the four surveys. Figure 3.9 shows the results of each of the individual surveys for each site.

Figure 3.9: Activity source of overall waste, by survey

 

Green Island Landfill Aug-07 Dec-07 Mar-08 May-08
Cover Material 73% 70% 24% 17%
General Waste 11% 11% 34% 53%
Kerbside Collections 5% 4% 8% 10%
Special Waste 5% 8% 25% 13%
Transfer Station 7% 6% 8% 8%
Silverstream landfill Aug-07 Nov-07 Feb-08 May-08
Cover Material 5% 3% 3% 6%
General Waste 41% 37% 16% 33%
Kerbside Collections 17% 19% 8% 18%
Special Waste 20% 19% 62% 26%
Transfer Station 18% 21% 11% 17%
Matamata Transfer Station Aug-07 Nov-07 Feb-08 May-08
Cover Material 0% 0% 0% 0%
General Waste 48% 47% 39% 41%
Kerbside Collections 52% 53% 61% 59%
Special Waste 0% 0% 0% 0%
Transfer Station 0% 0% 0% 0%
Kaikoura Landfill Sep-07 Nov-07 Feb-08 May-08
Cover Material 0% 0% 0% 0%
General Waste 79% 79% 76% 59%
Kerbside Collections 16% 16% 15% 12%
Special Waste 5% 5% 9% 29%
Transfer Station 0% 0% 0% 0%

At two of the sites, Kaikoura Landfill and Matamata Transfer Station, the proportions of the different sources were relatively consistent through the four surveys. At Kaikoura the proportion of special waste going to landfill increased as more glass (classified as special waste) was crushed and used as landfill cover rather than being stockpiled for later recovery. At Matamata the proportion of kerbside collections increased when another commercial waste operator started discharging at the facility.

At Green Island Landfill, the proportion of cover material decreased markedly between the second and third surveys when a gate charge was introduced. At Silverstream Landfill the proportion of special waste increased significantly during the third survey due to the disposal of material from a contaminated site.

3.3.3 Tonnage of overall waste

The tonnage of the overall waste stream from the four-week-long surveys is given for each site in Table 3.1. The average tonnage per week from the four surveys is also shown.

Table 3.1: Tonnage of overall waste stream

 

Round 1

Round 2

Round 3

Round 4

Average

Green Island Landfill 3293 3517 1833 1895 2635
Silverstream Landfill 2360 2245 5011 2107 2931
Matamata Transfer Station 88 96 99 100 96
Kaikoura Landfill 15 24 27 21 21

Figure 3.10 shows this data in graphical form. The tonnage for each survey at each site is shown as a percentage of the mean weekly tonnage at that site.

Figure 3.10: Weekly tonnage of overall waste as percentage of mean

 

Primary category Round 1 Round 2 Round 3 Round 4
Green Island Landfill 125% 133% 70% 72%
Silverstream Landfill 81% 77% 171% 72%
Matamata Transfer Station 92% 100% 103% 104%
Kaikoura Landfill 71% 114% 129% 100%

The weekly tonnage disposed of at Matamata Transfer Station is the only one of the four that remains relatively constant throughout the survey period. This is associated with there being no special waste or cover material disposed of at the site, because it is a transfer station rather than a landfill. The tonnages recorded at Kaikoura Landfill showed an increase in the summer season, then a decrease in the winter. This is likely due to seasonal variation in the tourism industry in Kaikoura.

For the other sites, where cover material and special waste comprised part of the overall waste, the tonnages vary more between the surveys because these types of waste tend to be less consistent. For example, the weekly tonnage of overall waste at Green Island Landfill decreased significantly between the second and third surveys, which was associated with the introduction of gate charges for cover material. At Silverstream Landfill there was a very marked increase in weekly tonnage for the third survey as a result of the disposal of a large quantity of contaminated spoil.

3.3.4 Average primary composition of overall waste

The average primary composition of the overall waste stream from each site is shown in Figure 3.11.

Figure 3.11: Average primary composition of overall waste

 

Primary category Green Island Landfill Silverstream Landfill Matamata Transfer Station Kaikoura Landfill
Paper 3% 6% 13% 9%
Plastics 2% 7% 13% 12%
Putrescibles 10% 22% 24% 26%
Ferrous metals 1.5% 3% 7% 4%
Non-ferrous metals 0.2% 0.4% 0.8% 0.7%
Glass 2% 3% 5% 18%
Textiles 1.4% 3% 5% 5%
Nappies and sanitary 0.5% 2.4% 7% 7%
Rubble 69% 4% 12% 7%
Timber 5% 12% 12% 8%
Rubber 0.3% 1.0% 0.4% 0.8%
Potentially hazardous 5% 37% 0.8% 1.3%

Apart from three major anomalies, the primary composition of the overall waste stream was relatively consistent between sites. The large quantities of cover material disposed of at Green Island Landfill during the first two surveys resulted in rubble comprising, on average, nearly 70 per cent of the overall waste at that site. The contaminated spoil disposed of at Silverstream Landfill led to potentially hazardous material representing 37 per cent, on average, of the overall waste at that site. At Kaikoura, glass that was crushed for cover material represented 18 per cent of the total. Putrescible material was the largest primary category at Matamata and Kaikoura, and the second largest at Green Island and Silverstream.