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Waste Solid Waste Audits for Ministry for the Environment Data Programme 2007/08 Online version
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:
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the compositions of the four activity sources that make up the general waste stream at both the transfer station and tip face
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the tonnages of the four activity sources and the general waste stream at both the transfer station and tip face
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the compositions of the general waste stream at both the transfer station and tip face
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the tonnages of the waste streams that make up the overall waste stream, including and excluding cover material
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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
Read text description for figure S6.1
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
Read text description for figure S6.2
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
Read text description for figure S6.3
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
Read text description for figure S6.4
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
Read text description for figure S6.5
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
Read text description for figure S6.6
Figure S6.7: Primary composition of general waste to transfer station, 2007/08
Read text description for figure S6.7
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
Read text description for figure S6.8
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
Read text description for figure S6.9
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
Read text description for figure S6.10
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
Read text description for figure S6.11
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
Read text description for figure S6.12
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
Read text description for figure S6.13
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
Read text description for figure S6.14
Figure S6.15: Primary composition of general waste to tip face, 2007/08
Read text description for figure S6.15
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
Read text description for figure S6.16
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
| 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
Read text description for figure S6.18
Figure S6.19: Primary composition of overall waste, including cover material, 2007/08
Read text description for figure S6.19
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
Read text description for figure S6.20
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
Read text description for figure S6.22
Figure S6.23: Primary composition of overall waste, excluding cover material, 2007/08
Read text description for figure S6.23
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 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
Read text description for figure S6.24
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.
