Zero waste initiative for plastics generated from a new build residential construction site

Abstract

In Auckland, 50% of the total waste stream is derived from construction and demolition waste, estimated at 568,935 tonnes in 2019. In comparison to other countries, the plastic proportion of NZ construction and demolition (C&D) waste is relatively large at approximately 4%. This amounts to approximately 25,000 tonnes of plastic waste sent to Auckland’s landfills every year, despite its potential economic value.

The concept of zero waste can be summarised as a goal that is ethical, economical, efficient and visionary, which guides people to lifestyle changes so that all discarded materials are designed to become resources for others to use. Zero waste is a target which looks beyond short-term improvements and focuses on radical and long-term change.

One construction company trialed a zero-waste project for a new-build residential construction site, with an aim of 90% diversion of all construction waste from landfill. This case study provided a unique opportunity to investigate the sources of various plastics resulting from construction waste and how they can be diverted from landfill via reuse and recycling. The collaborative efforts of Benton Ltd, Junk Run, Auckland Council, Environmental Solutions Research Centre (ESRC), saveBOARD, Marley NZ, DIVERT NZ and Polymer Processing NZ Ltd enabled plastic construction waste to be diverted, reused and recycled into new products.

All plastic waste was collected, audited and analysed using Fourier Transform Infrared spectroscopy (FTIR). Preliminary results show that the dominant plastic materials were polyethylene - PE (42.5% by mass), followed by expanded polystyrene - EPS (30.9%) and PVC pipes (13.2%). Of the waste audited so far, 60% of plastic waste has been recycled or reused, and diverted from landfill; however, it is estimated that 80% of plastic waste materials from this site can be easily recycled. Soft plastics (PE), EPS, polypropylene (PP) and PVC can be recycled into new components providing contamination is limited and/or removable.

Preliminary findings have identified reuse and recycling options for various plastic materials, and the requirements of plastics for such recycling. This research discusses options, tactics and barriers for separating plastic waste on site and identifies materials which cannot easily be recycled.