Data sources 2023-24
Waste Avoidance and Resource Recovery Regulations r.18C: annual returns
Regulation 18C of the WARR Regulations requires liable persons to report certain waste and recycling data annually to the department in accordance with approved procedures. The annual returns are lodged through an online portal. Ninety-seven liable recyclers, 15 liable landfills, 144 local governments and five regional councils lodged an 18C return for the 2023–24 reporting period.
The approved procedures for liable persons are available from the department’s website.
Waste levy data
Data collected by the department through administering the waste levy was used to estimate the disposal of waste generated in the Perth metropolitan region. This data included waste levy quarterly returns, waste levy exemptions and other supporting landfill records.
Waste exports
Waste export data is used to supplement recycling data for the metals, paper and cardboard, and textiles material categories. The export data was obtained from the Department of Climate Change, Energy, the Environment and Water’s Waste exports data collation.
Plastic recycling
Plastic recycling data was obtained both directly from recyclers and supplemented with data from the report (draft only) Australian plastic flows and fates 2023-24 – Western Australia, prepared for the department by Blue Environment.
Garden organics
Garden organics are commonly collected, mulched and composted by different recyclers, with the processed materials becoming different products at various points of the cycle. Previous audits have identified additional quantities of recovered garden organics not reported in 18C annual returns. These quantities were collected through a voluntary survey of local government transfer stations and incorporated into the data presented in this report.
Population
Population data for 2014–15 to 2023–23 was sourced from the Australian Bureau of Statistics as regional population (estimated resident population).
The number of domestic premises was sourced from the Australian Bureau of Statistics as occupied private dwellings. Linear projections were used to estimate intercensal years and to forecast future dwellings.
Waste material categories
All liable persons under the WARR Regulations reported recycling and landfill data against the waste material categories and types specified in the approved procedures. These categories and types have been consolidated in some figures and tables in the report to improve presentation.
Estimates made for material disposal
The quantity of waste disposed of to landfill by material type was estimated using compiled WA kerbside audit data (for MSW composition) and from landfill reports (for C&D waste stream composition).
Estimates made for waste disposal outside the Perth metropolitan area
The quantity of waste disposed of to landfill outside of the Perth metropolitan area was estimated by calculating per capita waste stream disposal rates for assumed catchment areas for liable non-metropolitan landfills and then applying those rates across the entire regional population.
Estimates made for some local governments
Under the WARR Regulations’ approved procedures for liable persons, there are special provisions for non-metropolitan local governments with populations of less than 1,500. Under these special provisions, the department estimated the quantity of waste collected, recovered and disposed of for at least one waste service for 39 local governments.
The estimates were based on the defaults in the approved procedures, and averages calculated from data reported by local government from 2019–20 to 2022–23.
Exported recyclables
All recyclable materials exported were assumed 100 per cent recovered. These quantities may include contaminants subsequently removed at the destination facility.
Waste generation and recovery rate calculation
Waste generation has been calculated as the sum of disposed waste and recovered waste. No other waste fates, such as long-term storage, have been included.
The recovery rate has been calculated as recovered waste divided by waste generation.
Recycling has been referred to as “material recovery” in previous reports.
Data quality
Measurement
Liable recyclers are required to report how they measured the quantity of reportable waste. In 2023–24, 28 per cent of reported recovered waste was weighed, 63 per cent was assessed by volume and the remainder was estimated using alternative methodologies.
The quantity of disposed waste arising from the Perth metropolitan region was estimated from records submitted with landfill levy returns. About 98 per cent of this reported waste was weighed.
The quantity of disposed waste arising from the Peel region was determined from liable non-metropolitan landfills. In 2023–24, 97 per cent of waste reported by liable non-metropolitan landfills was weighed. Waste disposal outside the Perth and Peel regions was estimated on a per capita basis, and is subject to a higher degree of uncertainty than directly reported disposal and recovery.
Point of measurement
Under the approved procedures, liable recyclers are required to report the amount of waste recovered, which includes processed and subsequently stockpiled materials. In practice, it has been observed that most recyclers are reporting recovered materials on an out-the-gate basis.
Audits
All annual returns were reviewed by department officers for completeness and consistency. Audits of six liable recyclers’ 2023–24 annual returns were also completed. The audit findings were incorporated into this report.
Comparability to previous reports
Data collected under regulation 18C of the WARR Regulations is presented in this report alongside data voluntarily reported to the department prior to 2019–20. The introduction of mandatory reporting resulted in additional reporters and any increases in tonnes of recovery may represent activity that was ongoing but not reported prior to mandatory reporting.
Waste disposal includes some waste that is disposed of to landfill but exempt from the waste levy. Metropolitan disposal shown in this report from 2019–20 onwards includes some waste disposal that was exempt from the levy which may not have been captured in previous years.
While the number of reporting local governments has increased with mandatory reporting, the populations of non-reporting local governments under the voluntary surveys were typically small. Consequently, the domestic waste data presented in this report is considered comparable to data contained in the census of Western Australian local government waste and recycling services series of reports.
Waste stream reporting
Under the approved procedures, liable recyclers and non-metropolitan landfills are required to record the source waste stream of waste received. Liable persons are directed, where possible, to record the waste stream from which the waste was generated. In practice, the department has observed that the waste stream in which waste is collected is often recorded.
Stockpiles
Tonnes of stockpiled waste presented in this report only include reported waste stored at liable persons’ premises at 30 June. No attempt has been made to estimate the quantity of waste stored elsewhere.
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