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S6 Summary of Results 2007/08

In this summary of the four surveys undertaken as part of the SWAP Baseline Data Programme, comparisons between the results of the four surveys are presented for:

  • the compositions of the four activity sources that make up the general waste stream at both the transfer station and tip face

  • the tonnages of the four activity sources and the general waste stream at both the transfer station and tip face

  • the compositions of the general waste stream at both the transfer station and tip face

  • the tonnages of the waste streams that make up the overall waste stream, including and excluding cover material

  • the compositions of the overall waste stream, including and excluding cover material.

S6.1 Transfer station activity sources

S6.1.1 Construction and demolition waste to transfer station

The primary composition of C&D waste from the four surveys is shown in Figure S6.1.

Figure S6.1: Composition of C&D waste to transfer station, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May
Paper 1.3% 3% 1.4% 2%
Plastics 3% 2% 2% 3%
Putrescibles 4% 5% 3% 3%
Ferrous metals 4% 4% 7% 4%
Non-ferrous metals 0.7% 0.0% 0.2% 0.3%
Glass 0.8% 1.2% 0.9% 2%
Textiles 4% 3% 2% 2%
Nappies and sanitary 0.0% 0.0% 0.0% 0.1%
Rubble 37% 33% 26% 22%
Timber 45% 49% 57% 62%
Rubber 0.1% 0.0% 0.0% 0.0%
Potentially hazardous 0.2% 0.3% 0.2% 0.4%

In each of the four surveys, rubble and timber were the largest components of C&D waste. Although there is variation between surveys in terms of the relative proportions of rubble and timber (with rubble decreasing in every survey and timber increasing), in every survey rubble and timber, when combined, comprised over 81 per cent of C&D waste. No other material comprised more than 7 per cent of the total.

S6.1.2 Industrial/commercial/institutional waste to transfer station

The primary composition of ICI waste from the four surveys is shown in Figure S6.2.

Figure S6.2: Composition of ICI waste to transfer station, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May
Paper 14% 9% 9% 5%
Plastics 14% 8% 8% 7%
Putrescibles 11% 8% 8% 5%
Ferrous metals 8% 6% 5% 3%
Non-ferrous metals 0.5% 2% 1.1% 0.4%
Glass 4% 7% 8% 2%
Textiles 5% 11% 12% 4%
Nappies and sanitary 0.8% 1.1% 1.4% 0.7%
Rubble 2% 6% 4% 1.0%
Timber 16% 14% 11% 15%
Rubber 24% 30% 31% 57%
Potentially hazardous 3% 0.5% 2% 0.2%

In each of the four surveys, rubber (in the form of used tyres) was the largest single classification of ICI waste discharged at the transfer station. As a proportion of the total, rubber varied between 24 and 56 per cent. Timber is the second largest component in three of the four surveys, with textiles the second largest in the third survey.

S6.1.3 Landscaping and earthworks waste to transfer station

The primary composition of landscaping and earthworks waste from the four surveys is shown in Figure S6.3.

Figure S6.3: Composition of landscaping and earthworks waste to transfer station, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May
Paper 0.3% 0.8% 0.3% 0.4%
Plastics 0.6% 0.7% 0.5% 0.5%
Putrescibles 79% 84% 84% 84%
Ferrous metals 0.6% 0.7% 0.6% 0.5%
Non-ferrous metals 0.0% 0.0% 0.0% 0.0%
Glass 0.0% 0.3% 0.2% 0.3%
Textiles 0.2% 0.7% 0.5% 0.4%
Nappies and sanitary 0.0% 0.1% 0.1% 0.2%
Rubble 19% 10% 10% 10%
Timber 0.9% 3% 3% 4%
Rubber 0.1% 0.1% 0.0% 0.0%
Potentially hazardous 0.3% 0.0% 0.0% 0.0%

Results from the four surveys show the composition of the landscaping and earthworks activity source is made up of two primary categories: putrescibles and rubble. In all of the four audits, green waste and rubble combined represented over 93 per cent of the total weight. Green waste, much of it disposed of at the separate green waste drop-off point, comprised over 78 per cent of the total in all four surveys.

S6.1.4 Residential waste to transfer station

The primary composition of residential waste from the four surveys is shown in Figure S6.4.

Figure S6.4: Composition of residential waste to transfer station, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May
Paper 8% 10% 10% 9%
Plastics 10% 10% 10% 9%
Putrescibles 19% 23% 20% 23%
Ferrous metals 13% 13% 14% 11%
Non-ferrous metals 0.4% 0.6% 0.7% 0.6%
Glass 3% 4% 3% 3%
Textiles 10% 10% 9% 12%
Nappies and sanitary 1.2% 2% 2% 2%
Rubble 7% 3% 5% 4%
Timber 28% 22% 26% 24%
Rubber 1.2% 0.7% 0.8% 0.9%
Potentially hazardous 0.7% 0.7% 0.8% 0.6%

Residential waste is relatively heterogeneous, with no single category of material comprising more than 28 per cent of the total in any of the surveys. In three of the surveys timber was the largest classification and putrescibles the second largest; in the second survey, putrescibles was the largest and timber the second largest. The putrescible material was roughly equal parts green waste and food waste (contained in domestic refuse bags). All of the 12 primary waste categories were relatively consistent across the four surveys.

S6.2 Transfer station general waste

General waste discharged at the transfer station is defined as waste being generated from four different activity sources: C&D, ICI, landscaping and earthworks, and residential (as illustrated in Figure S1.1). Figure S6.5 presents the tonnage of waste from each activity source for each of the four surveys.

Figure S6.5: Tonnage of activity sources of general waste to transfer station, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May
Construction and Demolition 76 55 83 43
Industrial/Commercial/ Institutional 45 32 41 42
Landscaping and Earthworks 132 201 235 145
Residential 165 178 208 126
Total General Waste 418 466 568 356

Figure S6.5 shows that general waste disposed of at the transfer station increased by about 11 per cent between the first and second surveys, and by a further 15 per cent between the second and third surveys. These increases are associated with a substantial increase in the quantity of green waste. The general waste then decreased 19 per cent between the third and fourth surveys. This was the result of three of the four activity sources decreasing between the third and fourth surveys, with only ICI waste not decreasing.

The tonnage of C&D waste was lowest in the May survey, which may relate to seasonal trends in the construction industry. ICI waste was the most consistent of the four waste streams. Waste from landscaping and earthworks activities was the highest in three of the four surveys, with a peak in the summer audit in February.

Figures S6.6 and S6.7 present the variation in the composition of the general waste stream through the four surveys conducted in 2007/08. Figure S6.6 shows the tonnage of each of the 12 primary categories disposed of during each of the survey periods; the mean tonnage is also shown in the figure. Figure S6.7 shows the percentage of the general waste stream for each of the 12 primary SWAP categories.

Figure S6.6: Tonnage of general waste to transfer station, by primary categories, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May Mean
Paper 21 24 25 14 21
Plastics 25 23 26 16 23
Putrescibles 143 214 245 155 189
Ferrous metals 28 28 37 17 28
Non-ferrous metals 1.0 2 2 1.0 2
Glass 6 10 11 6 8
Textiles 22 25 27 18 23
Nappies and sanitary 2 5 5 4 4
Rubble 65 46 58 29 50
Timber 89 76 115 69 87
Rubber 13 11 14 25 16
Potentially hazardous 3 2 2 1.0 2

Figure S6.7: Primary composition of general waste to transfer station, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May
Paper 5% 5% 5% 4%
Plastics 6% 5% 5% 5%
Putrescibles 34% 46% 43% 44%
Ferrous metals 7% 6% 7% 5%
Non-ferrous metals 0.3% 0.4% 0.4% 0.3%
Glass 2% 2% 2% 2%
Textiles 5% 5% 5% 5%
Nappies and sanitary 0.6% 1.1% 0.9% 1.0%
Rubble 16% 10% 10% 8%
Timber 21% 16% 20% 20%
Rubber 3% 2% 3% 7%
Potentially hazardous 0.7% 0.4% 0.4% 0.3%

The graphs show that putrescible material makes up the largest proportion of general waste in each survey. Because putrescible material is a major component of residential waste and landscaping waste, the tonnage of putrescible material varies considerably as the quantity of waste from these sources varies seasonally. Timber is the second largest component in each survey.

The average proportions of the 12 SWAP primary waste categories that make up general waste are presented in Figure S6.8. The average composition is calculated using the results from the four visual surveys conducted in 2007/08 and is based on the tonnages of the different materials. These are the mean figures from Figure S6.6 expressed as percentages.

Figure S6.8: Average primary composition of general waste to transfer station, 2007/08

Primary category % of total
Paper 5%
Plastics 5%
Putrescibles 42%
Ferrous metals 6%
Non-ferrous metals 0.3%
Glass 2%
Textiles 5%
Nappies and sanitary 0.9%
Rubble 11%
Timber 19%
Rubber 3%
Potentially hazardous 0.4%

Putrescibles and timber make up the largest components of the general waste stream (42 per cent and 19 per cent, respectively), reflecting the large proportion of waste generated from residential and landscaping activity (refer Figure S6.5). Rubble is the third largest component, with 11 per cent of the total. Paper, plastics, ferrous metals and the textiles categories each make up between 5 and 6 per cent of the general waste composition.

S6.3 Tip face activity sources

S6.3.1 Construction and demolition waste to tip face

The primary composition of C&D waste discharged at the tip face during the four surveys is shown in Figure S6.9.

Figure S6.9: Composition of C&D waste to tip face, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May
Paper 4% 4% 3% 5%
Plastics 4% 4% 5% 5%
Putrescibles 1.0% 3% 8% 4%
Ferrous metals 7% 8% 7% 3%
Non-ferrous metals 0.2% 0.1% 0.2% 0.1%
Glass 2% 1.4% 1.0% 0.4%
Textiles 0.7% 2% 1.0% 0.6%
Nappies and sanitary 0.1% 0.0% 0.2% 0.0%
Rubble 23% 14% 34% 21%
Timber 57% 63% 41% 55%
Rubber 0.4% 0.4% 0.1% 5%
Potentially hazardous 0.7% 0.4% 0.5% 0.1%

Timber was the largest component of C&D waste in all of the four surveys, and rubble (such as concrete) was the second largest component. Together, rubble and timber comprised over 74 per cent of the total in each of the surveys.

S6.3.2 Industrial/commercial/institutional waste to tip face

The primary composition of ICI waste from the four surveys is shown in Figure S6.10.

Figure S6.10: Composition of ICI waste to tip face, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May
Paper 11% 13% 11% 13%
Plastics 21% 19% 16% 15%
Putrescibles 21% 24% 22% 25%
Ferrous metals 6% 6% 5% 5%
Non-ferrous metals 1.2% 0.7% 0.7% 0.8%
Glass 7% 8% 16% 6%
Textiles 7% 7% 7% 6%
Nappies and sanitary 4% 4% 4% 5%
Rubble 4% 3% 2% 3%
Timber 13% 12% 14% 17%
Rubber 3% 1.4% 0.8% 0.9%
Potentially hazardous 3% 2% 2% 4%

ICI waste was relatively heterogeneous, with no single material comprising over 25 per cent of the total in any of the surveys. The putrescibles category was largest in all of the surveys, with plastics second largest in three of the surveys and timber second largest in the fourth. Much of the plastic was generated by a recycling processor, and this waste stream decreased considerably during the fourth survey.

For most of the categories there is reasonable consistency between surveys in terms of the proportion of the materials present. The large increase in glass in the third survey is also due to waste from a recycling processor.

S6.3.3 Landscaping and earthworks waste to tip face

The primary composition of landscaping and earthworks waste from the four surveys is shown in Figure S6.11.

Figure S6.11: Composition of landscaping and earthworks waste to tip face, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May
Paper 0.0% 0.5% 3% 0.5%
Plastics 0.1% 2% 1.3% 0.5%
Putrescibles 78% 72% 85% 53%
Ferrous metals 1.1% 1.2% 0.7% 0.1%
Non-ferrous metals 0.0% 0.0% 0.0% 0.0%
Glass 0.0% 0.1% 0.0% 0.3%
Textiles 0.4% 0.4% 0.7% 0.1%
Nappies and sanitary 0.0% 0.0% 0.1% 0.1%
Rubble 14% 21% 3% 39%
Timber 6% 3% 2% 6%
Rubber 0.0% 0.0% 4% 0.0%
Potentially hazardous 0.0% 0.0% 0.0% 0.0%

Results from the four surveys show the composition of the landscaping and earthworks activity source is generally made up almost exclusively of two primary waste categories, putrescibles and rubble, which together comprised over 87 per cent of the total in all four surveys. In all of the four surveys putrescibles was the largest component, with between 53 and 85 per cent of the total weight.

S6.3.4 Residential waste

The primary composition of residential waste from the four surveys is shown in Figure S6.12.

Figure S6.12: Composition of residential waste to tip face, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May
Paper 6% 6% 7% 7%
Plastics 12% 9% 12% 11%
Putrescibles 10% 15% 13% 10%
Ferrous metals 18% 18% 20% 16%
Non-ferrous metals 0.8% 0.7% 0.9% 0.8%
Glass 4% 3% 4% 4%
Textiles 12% 12% 12% 12%
Nappies and sanitary 0.8% 0.2% 0.7% 0.0%
Rubble 8% 9% 5% 9%
Timber 28% 27% 24% 29%
Rubber 0.7% 0.7% 0.8% 1.0%
Potentially hazardous 0.8% 0.8% 1.3% 2%

Residential waste is relatively heterogeneous, with no single category of material comprising more than 29 per cent of the total in any of the surveys. In all of the surveys timber was the largest classification and ferrous metals the second largest. All of the materials are relatively consistent between the surveys.

S6.4 General waste to tip face

General waste discharged at the tip face is defined as waste being generated from four different activity sources: C&D, ICI, landscaping and earthworks, and residential (as illustrated in Figure S1.1). Figure S6.13 presents the tonnage of waste from each activity source for each of the four surveys.

Figure S6.13: Tonnage of activity sources of general waste to tip face, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May
Construction and Demolition 90 89 22 66
Industrial/Commercial/ Institutional 847 668 698 583
Landscaping and Earthworks 16 42 34 59
Residential 23 37 48 34
Total General Waste 976 837 802 741

Figure S6.13 shows that the total quantity of general waste disposed of at the tip face decreased by approximately 140 tonnes (15 per cent) between the first and second surveys of this series, and a further 35 tonnes (4 per cent) between the second and third surveys. Between the third and fourth surveys general waste decreased a further 8 per cent. Overall, there was a 24 per cent decrease in general waste disposed of at the tip face between the first and fourth surveys. This was associated with a decrease in ICI waste, and most of that decrease was related to a single waste operator. This decrease is considered likely by the writer to be associated with a change in disposal sites by that waste operator rather than an actual decrease in the amount of ICI waste being generated in the Hutt region.

C&D waste was constant in the first two surveys, but decreased significantly during the third survey. Given that the tonnage then increased again, this pattern may reflect variations in seasonal activity in the building industry.

Figures S6.14 and S6.15 present the variation in the composition of the general waste stream through the four surveys conducted in 2007/08. Figure S6.14 shows the tonnage of each of the 12 primary categories disposed of during each of the survey periods; the mean tonnage is also shown in the figure. Figure S6.15 shows the percentage of the general waste stream discharged at the tip face for each of the 12 primary SWAP categories.

Figure S6.14: Tonnage of general waste to tip face, by primary categories, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May Mean
Paper 99 94 81 81 89
Plastics 192 137 122 96 137
Putrescibles 196 198 187 181 191
Ferrous metals 58 53 46 37 49
Non-ferrous metals 10 5 5 5 6
Glass 58 55 115 35 66
Textiles 58 50 54 40 51
Nappies and sanitary 31 26 27 27 28
Rubble 54 47 27 55 46
Timber 167 147 117 150 145
Rubber 23 10 7 9 12
Potentially hazardous 28 14 13 23 20

Figure S6.15: Primary composition of general waste to tip face, 2007/08

Primary category 18-24 August 23-29 November 21-27 February 17-23 May
Paper 10% 11% 10% 11%
Plastics 20% 16% 15% 13%
Putrescibles 20% 24% 23% 24%
Ferrous metals 6% 6% 6% 5%
Non-ferrous metals 1.1% 0.6% 0.7% 0.7%
Glass 6% 7% 14% 5%
Textiles 6% 6% 7% 5%
Nappies and sanitary 3% 3% 3% 4%
Rubble 6% 6% 3% 8%
Timber 17% 18% 15% 20%
Rubber 2% 1.2% 0.9% 1.2%
Potentially hazardous 3% 2% 2% 3%

The graphs show that putrescibles made up the largest proportion of general waste in all four surveys. The quantities of plastics and glass, which were associated with a recycling processor, varied considerably between the surveys. The other classifications varied to a lesser degree.

The average proportions of the 12 SWAP primary waste categories that make up general waste are presented in Figure S6.16. The average composition is calculated using results from the four visual surveys conducted in 2007/08 and is based on the tonnages of the different materials. These are the mean figures from Figure S6.14 expressed as percentages.

Figure S6.16: Average primary composition of general waste to tip face, 2007/08

Primary category % of total
Paper 11%
Plastics 16%
Putrescibles 23%
Ferrous metals 6%
Non-ferrous metals 0.7%
Glass 8%
Textiles 6%
Nappies and sanitary 3%
Rubble 5%
Timber 17%
Rubber 1.5%
Potentially hazardous 2%

Putrescibles and timber made up the largest components of the general waste stream (23 per cent and 17 per cent, respectively), reflecting the large proportion of waste generated by ICI activity (refer Figure S6.13). Plastics comprised 16 per cent of the total and paper 11 per cent. All other materials comprised less than 8 per cent of the total.

S6.5 Overall waste, including cover material

Table S6.1 and Figure S6.17 show the tonnage of overall waste, by activity source, from the results of the four surveys. Cover material is included in the analysis.

Table S6.1: Overall waste, including cover material, 2007/08

Table S6.2:Overall waste, excluding cover material, 2007/08

Waste types Tonnes/week
August 2007 November 2007 February 2008 May 2008
Cover material 111 75 138 127
General waste 976 837 802 697
Kerbside collections 391 432 411 386
Special waste 464 435 3091 542
Transfer station 418 466 568 356
Total 2360 2245 5011 2107

Figure S6.17: Overall waste, including cover material, 2007/08

Four of the five waste types that comprised the overall waste were relatively consistent during the survey period. Kerbside collections were the most consistent of the waste types. The quantity of cover material (all of which was sawdust) varied somewhat, probably due to seasonal variation in production at the sawmill. General waste decreased with each survey (see Section S6.4). Waste from the transfer station increased during the first three surveys, then decreased in the fourth. This may be due to seasonal variations in the activity of small waste generators, or it could have been a result of a decline in economic conditions.

Special waste increased markedly in the third survey as a result of the disposal of a large amount of contaminated fill from a research facility. The quantity of meat-processing waste (classified as a special waste) being disposed of at the facility increased from 20 tonnes per week during the first survey to over 100 tonnes per week during the second and third surveys. This decreased to 90 tonnes per week during the fourth survey. This may be due to seasonal variations in meat-processing activity.

Figures S6.18 and S6.19 present the variation in the composition of the overall waste stream, including cover material, through the four surveys conducted in 2007/08. Figure S6.18 shows the tonnage of each of the 12 primary categories disposed of during each of the week-long survey periods; the mean tonnage is also shown in the graph. Figure S6.19 shows the composition of the overall waste stream for each of the 12 primary SWAP categories.

Figure S6.18: Tonnage of overall waste, including cover material, by primary categories, 2007/08

Primary category 6-12 August 20-26 November 12-18 February 5-11 May Mean
Paper 177 181 166 146 168
Plastics 262 222 207 162 213
Putrescibles 528 723 732 603 647
Ferrous metals 97 93 95 62 87
Non-ferrous metals 14 10 10 8 11
Glass 83 83 143 56 91
Textiles 89 84 90 64 82
Nappies and sanitary 72 74 73 67 72
Rubble 132 101 93 89 104
Timber 371 300 372 339 346
Rubber 36 21 22 34 28
Potentially hazardous 498 354 3,010 477 1085

Figure S6.19: Primary composition of overall waste, including cover material, 2007/08

Primary category 6-12 August 20-26 November 12-18 February 5-11 May
Paper 8% 8% 3% 7%
Plastics 11% 10% 4% 8%
Putrescibles 22% 32% 15% 29%
Ferrous metals 4% 4% 2% 3%
Non-ferrous metals 0.6% 0.4% 0.2% 0.4%
Glass 4% 4% 3% 3%
Textiles 4% 4% 2% 3%
Nappies and sanitary 3% 3% 1.4% 3%
Rubble 6% 5% 2% 4%
Timber 16% 13% 7% 16%
Rubber 2% 0.9% 0.4% 2%
Potentially hazardous 21% 16% 60% 23%

The graphs show that, other than potentially hazardous material (contaminated fill from a research facility), the tonnage of most of the primary materials was relatively consistent through the survey period. There is some variation in the quantities of plastics and glass, which appeared to be associated with changes in disposal behaviour by a recycling processor.

The average primary composition of the overall waste stream, including cover material, is presented in Figure S6.20. The average composition for the four surveys has been calculated by averaging the tonnages from each survey. These averages are shown as the mean in Figure S6.18.

Figure S6.20: Average primary composition of overall waste, including cover material, 2007/08

Primary category % of total
Paper 6%
Plastics 7%
Putrescibles 22%
Ferrous metals 3%
Non-ferrous metals 0.4%
Glass 3%
Textiles 3%
Nappies and sanitary 2.4%
Rubble 4%
Timber 12%
Rubber 1.0%
Potentially hazardous 37%

Potentially hazardous material, most of it contaminated fill, was the largest primary category, comprising 37 per cent of the total. Putrescibles was the second largest category, comprising 22 per cent of the total.

S6.6 Overall waste, excluding cover material

Table S6.2 and Figure S6.21 show the quantity of the different waste types in the overall waste from the results of the four surveys. Cover material is excluded from this analysis.

Table S6.2: Overall waste, excluding cover material, 2007/08

Waste types Tonnes/week

August 2007

November 2007

February 2008

May 2008

General waste 976 837 802 697
Kerbside collections 391 432 411 386
Special waste 464 435 3091 542
Transfer station 418 466 568 356
Total 2249 2170 4873 1981

Figure S6.21: Overall waste, excluding cover material, 2007/08

Three of the four waste types that comprised the overall waste, when cover material is excluded, were relatively consistent during the survey period. Kerbside collections was the most consistent of the waste types. General waste decreased with each survey (see Section S6.4). Waste from the transfer station increased during the first three surveys, then decreased in the fourth. This may be due to seasonal variations in the activity of small waste generators, or it could have been a result of a decline in economic conditions. Special waste increased markedly in the third survey as a result of the disposal of a large amount of contaminated fill from a research facility.

Figures S6.22 and S6.23 on the following page present the variation in the composition of the overall waste stream, excluding cover material, through the four surveys conducted in 2007/08. Figure S6.22 shows the tonnage of each of the 12 primary categories disposed of during each of the survey periods. The mean tonnage is also shown in the graph. Figure S6.23 shows the percentage composition of the overall residual waste stream for each of the 12 primary SWAP categories.

Figure S6.22: Tonnage of overall waste, excluding cover material, by primary categories, 2007/08

Primary category 6-12 August 20-26 November 12-18 February 5-11 May Mean
Paper 177 181 166 146 168
Plastics 262 222 207 162 213
Putrescibles 528 723 732 603 647
Ferrous metals 97 93 95 62 87
Non-ferrous metals 14 10 10 8 11
Glass 83 83 143 56 91
Textiles 89 84 90 64 82
Nappies and sanitary 72 74 73 67 72
Rubble 132 101 93 89 104
Timber 260 225 234 213 233
Rubber 36 21 22 34 28
Potentially hazardous 498 354 3,010 477 1085

Figure S6.23: Primary composition of overall waste, excluding cover material, 2007/08

Primary category 6-12 August 20-26 November 12-18 February 5-11 May
Paper 8% 8% 3% 7%
Plastics 12% 10% 4% 8%
Putrescibles 24% 33% 15% 31%
Ferrous metals 4% 4% 2% 3%
Non-ferrous metals 0.6% 0.4% 0.2% 0.4%
Glass 4% 4% 3% 3%
Textiles 4% 4% 2% 3%
Nappies and sanitary 3% 3% 2% 3%
Rubble 6% 5% 2% 5%
Timber 12% 10% 5% 11%
Rubber 2% 1.0% 0.5% 2%
Potentially hazardous 22% 16% 62% 24%

The graphs show that, other than potentially hazardous material (contaminated fill from a research facility), the tonnage of most of the primary materials was relatively consistent through the survey period. There is some variation in the quantities of plastics and glass due to changes in disposal behaviour by a recycling processor.

The primary composition of the overall waste stream, excluding cover material, is presented in Figure S6.24. The average composition for the four surveys has been calculated by averaging the tonnages from each survey. These averages are shown as the mean in Figure S6.22.

Figure S6.24: Average primary composition of overall waste, excluding cover material, 2007/08

Primary category % of total
Paper 6%
Plastics 8%
Putrescibles 23%
Ferrous metals 3%
Non-ferrous metals 0.4%
Glass 3%
Textiles 3%
Nappies and sanitary 3%
Rubble 4%
Timber 8%
Rubber 1.0%
Potentially hazardous 38%

Potentially hazardous material, most of it contaminated fill, was the largest primary category, comprising 39 per cent of the total. Putrescibles was the second largest category, with 23 per cent of the total.