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2. Total waste stream and quantities of plastic, glass and tyres
2.1 Introduction
In order to investigate the potential for a regional waste recovery / processing sector for tyres, plastic and glass it is necessary to estimate the existing and predicted quantity of recovered material available in a given geographical area. Initial estimates for plastic and glass were determined using information provided by Wellington, Porirua, Lower and Upper Hutt City Councils from which potential diversion quantities have been assumed. A wider region was also considered and recyclate generated from Kapiti Coast, Masterton, Carterton and South Wairarapa Districts were also included. The quantification of tyres is addressed separately.
2.2 Quantity of Plastic & Glass
2.2.1 Wellington City
Weighbridge records for the 2001/02 financial year were used as the basis for assessment of waste quantities entering the Northern and Southern Landfills. The total quantity of material landfilled was 69,506 tonnes and 72,891 tonnes, respectively, making a total of 142,397 tonnes.
A Waste Analysis Protocol (WAP) survey was carried on both landfill sites in 1998. In 2002 an updated Solid Waste Analysis Protocol (SWAP) survey was undertaken. For the purposes of this study, the following is the assessed waste composition, based on the 2002 survey.
Table 2.1: Glass and plastic waste as assessed in Wellington City Solid Waste Analysis survey 2002
| Waste Component for Northern Landfill | % of Total Waste | Estimate Annual Tonnes |
|---|---|---|
| Plastic |
6.8 |
4,759 |
| Glass |
1.8 |
1,259 |
| Waste Component for Southern Landfill | % of Total Waste | Estimate Annual Tonnes |
|---|---|---|
| Plastic |
8.1 |
5,877 |
| Glass |
4.7 |
3,403 |
| Total for Wellington City | Estimate Annual Tonnes |
|---|---|
| Plastic |
10,636 |
| Glass |
4,662 |
Wellington City Council provides a weekly kerbside collection for recyclable materials to households. Approximately 8,300 tonnes of material was collected in 2002. The Council also provides eight collection points for recyclable materials with approximately 1,200 tonnes of material collected and recycled by this means per annum. The total quantity of material recovered from the residential waste steam in 2002 was 9,500 tonnes, comprising approximately 3,300 tonnes of glass and 720 tonnes of plastic.
2.2.2 Hutt City Council
Weighbridge records for the 2001/02 financial year were used as the basis for assessment of waste quantities entering the Silverstream and Wainuiomata Landfills. The total quantity of material landfilled was 103,127 tonnes and 24,248 tonnes, respectively, making the total quantity of waste landfilled in Hutt City 127,375 tonnes.
A Waste Analysis Protocol (WAP) survey was carried on the landfill site in 1998. For the purposes of this study, the following is the assessed waste composition.
Table 2.2: Glass and plastic waste as assessed in Hutt City Waste Analysis survey 1998
| Waste Component for Silverstream Landfill | % of Total Waste | Estimate Annual Tonnes |
|---|---|---|
| Plastic |
7.9 |
8,147 |
| Glass |
1.9 |
1,959 |
| Waste Component for Wainuiomata Landfill | % of Total Waste | Estimate Annual Tonnes |
|---|---|---|
| Plastic |
6.5 |
1,576 |
| Glass |
1.3 |
315 |
| Total for Hutt City | Estimate Annual Tonnes |
|---|---|
| Plastic |
9,723 |
| Glass |
2,274 |
Hutt City Council provides a weekly kerbside collection system for recyclable materials to households with approximately 3,615 tonnes of material recovered from May - June 2002. In addition, the Council provides five collection points for recyclable materials which is taken to All Brite's recycling facility in Hutt City processing. Approximately 270 tonnes of material is recovered by this means each year (from records in May-June 2002). Therefore the total quantity of material recycled in Hutt City for residential waste sources was 3435 tonnes. Based on the proportion of glass (37%) and plastic (8%) recovered from the Wellington recycling systems, approximately 1,271 tonnes of glass and 275 tonnes of plastic were recovered in Hutt City.
2.2.3 Porirua City Council
Weighbridge records for May 2002 to July 2002 were used as the basis for assessment of waste quantities entering the Spicer Landfill. Prior to this period there was no weighbridge at the landfill and all records of incoming waste were as estimates of volume. It was considered that the short period of weighbridge records was likely to provide a better assessment of incoming refuse than the volume estimates. The total quantity of material landfilled at Spicer landfill in Porirua City in 2002 was 93,325 tonnes. In addition a kerbside collection for recyclables, in conjunction with the refuse collection was introduced in 2002 for households in the urban area. Measurement of quantities collected over the three months of July to September 2002 indicates that approximately 2,380 tonnes of recyclable material would be collected each year.
The Council also provides a number of collection points for recyclable materials. Data on the quantity of recyclable material collected in September 2002 indicates that 480 tonnes of recyclable material would be collected each year making the total quantity of material recovered from the residential waste stream 2,860 tonnes. Based on the proportion of glass (37%) and plastic (8%) recovered from the Wellington recycling systems, approximately 1,058 tonnes of glass and 229 tonnes of plastic were recovered in Porirua City.
A Waste Analysis Protocol (WAP) survey was carried on the landfill site in 1995. The composition reported in that survey was as follows:
Table 2.3: Glass and plastic waste as measured in Waste Analysis Survey, Spicers Landfill, Porirua 1995
| Waste Component | % of Total Waste | Estimate Annual Tonnes |
|---|---|---|
| Plastic |
5.3 |
4,986 |
| Glass |
1.3 |
1,246 |
2.2.4 Summary for Plastic and Glass Quantities
The following table summarises the waste stream for each landfill and the total for the region and also the estimated quantity of plastic and glass.
Table 2.4 Summary of findings from waste surveys at Wellington landfills
| Site | Total (tonnes) |
Glass (tonnes) |
Plastic (tonnes) |
|---|---|---|---|
| Northern Landfill |
69,506 |
1,259 |
4,759 |
| Southern Landfill |
72,891 |
3,403 |
5,877 |
| Silverstream Landfill |
103,127 |
1,959 |
8,147 |
| Wainuiomata Landfill |
24,248 |
315 |
1,576 |
| Spicer Landfill |
93,325 |
1,246 |
4,986 |
| Total for the region |
363,097 |
8,182 |
25,345 |
2.3 Quantity of Tyres
An extensive amount of research has been carried out overseas regarding the use and performance of tyres. In order to determine the numbers and quantity of tyres that are in circulation an approximate figure of 1 tyre per person per year has been used (Brash, 1999, Amirkhanian, 2001 & CIWMB, 2002). The European Tyre Recycling Association reported that tyre generation equated to 6.6 kg/person/year, while the California Integrated Waste Management Board (CIWMB) used a figure of 9kg/person to account for passenger tyres, while large industrial and agricultural tyres remaining unaccounted for (CIWMB, 2002 & CIWMB 1999). The CIWMB advises that on an annual basis the generation of tyres is equivalent to population, therefore for the purposes of this study this principle has been adopted (CIWMB, 2002).
Brash (1999) determined that in 1999 New Zealand generated approximately 3.8 million waste tyres per annum including approximately 424,000 imported used tyres, which supports the theory provided by the CIWMB. The current population of New Zealand is estimated to be 4,000,000, which equates to 36,000 tonnes of waste tyres generated per annum across the country. This is confirmed by Bridgestone Firestone and South Pacific Tyres, who are the largest suppliers of new tyres to the New Zealand market, with an estimated 2 million units annually. They estimate that 30,000 tonnes comprise car and truck tyres, while 5,500 large tyres are generated from industry and agriculture (Personal Communication1, 2003).
The quantity of waste tyres generated across the Wellington region is calculated using the principle of one waste tyre generated per person pr year. Thus population estimates are used for each area and the average weight of a tyre was determined as 9kg (Brash, 1999, Amirkhanian, 2001 & CIWMB, 2002).
2.4 Summary of the Quantities of Plastic, Glass and Tyres
The following table summarises the total quantity of waste landfilled in each area, the estimated proportion of glass, plastic and tyres in each waste stream and the quantity of glass and plastic currently diverted from landfill. All quantities are shown in tonnes.
Table 2.5: Estimates of materials landfilled and recovered for selected cities in Wellington region
| City | Total Landfilled | Glass Landfilled | Glass Diverted | Total Glass | Plastic Landfilled | Plastic Diverted | Total Plastic | Tyres |
|---|---|---|---|---|---|---|---|---|
| Wellington |
142,397 |
5,921 |
3,300 |
9,221 |
10,636 |
720 |
11,356 |
1,516 |
| Lower Hutt |
127,375 |
2,274 |
1,271 |
3,545 |
9,726 |
275 |
10,001 |
876 |
| Upper Hutt |
* |
* |
999 |
999 |
* |
216 |
216 |
318 |
| Porirua |
93,325 |
1,246 |
1,058 |
2,304 |
4,986 |
229 |
5,215 |
424 |
| Total |
363,097 |
9,441 |
6,628 |
16,069 |
25,348 |
1,440 |
26,788 |
3,134 |
* Upper Hutt's waste stream is included in Lower Hutt landfill figures
It can be seen that compared to plastic, a significant proportion of the glass waste stream is already being diverted from landfill, with 6,628 tonnes diverted and 9,441 tonnes landfilled. Conversely, the quantity of plastic diverted from landfill is 1,440 tonnes, while 25,348 tonnes is landfilled per annum across the region. It remains therefore that greater emphasis is needed with regards to the source segregation and collection of the various plastic polymers to increase the volume of material available for reprocessing.
