Construction and demolition waste in Western Australia: A case study on best practice demolition

The C&D waste sector is the only sector in which waste generation has increased in Australia, and most recent data shows WA diversion of C&D waste from landfill to be 57% [1, 2]. This is low compared to countries such as Japan and the Netherlands which achieve diversion rates of 97% and 95% respectively. In addition to this, the extraction and production of raw construction materials can result in large amounts of greenhouse gas emissions which are harmful to the environment. The reuse and recycle of C&D materials can help to alleviate both problems and as such WA’s transition towards a circular economy is of high importance to the current waste industry. The aim of this study is to identify barriers and opportunities which contribute to a higher rate of reuse, recycle and recovery in best practice demolition, and the transition towards a circular economy in the C&D sector of WA. The Hamilton Senior High School (HSHS) demolition was chosen as a case study due to the use of best practice demolition techniques, including onsite crushing activity and direct recycle/reuse. The four objectives achieved under this study include: 1. Gain an understanding of current issues or innovations within the C&D waste sector; 2. Identify the waste contribution of the HSHS demolition to the WA waste stream and stockpiling, and if this could be further improved; 3. Determine the environmental impacts/savings of conducting a demolition and potential construction using WA best practice; 4. Determine the economic viability of conducting best practice demolition in WA The methods chosen to achieve these objectives were industry surveys, total waste quantification at the HSHS site, environmental impact assessment via carbon footprint, economic assessment via cost benefit analysis, and a comparison to a business as usual and worst case scenario. Successful achievement of the objectives identified a significant problem with illegal disposal practices occurring to avoid landfill levy payments. Lack of regulation, voluntary reporting, lack of economic incentive (including market for products) and ineffective landfill levy application to regional areas were also identified to be barriers to higher recycle and reuse. Results also displayed the environmental and economic benefits of this demolition. Best practice techniques resulted in the highest net GHG abatement (327 tCO2e), low contribution to the C&D waste/stockpiling streams (10200 t, or 92.7% recycled material), and cost savings generated by lower raw material use, transport and waste fees (saving approximately $252,000). The HSHS demolition was however, the most expensive scenario, with approximately $1,900,000 comparable costs. Further research could be conducted on the application of higher direct reuse and possibly design for deconstruction to improve material circularity. It is recommended that regulation surrounding the landfill levy should be put in place to discourage illegal practices. In addition, economic incentive could be provided in the form of lower labour taxes, and higher raw materials tax to encourage best practice demolition techniques