ER110 Plastic waste in construction Report 3 - Opportunities for plastic waste management: Lower South Island (May 2025)

This research investigated options for the recycling of construction plastic waste in the South Island. This involved trialling on-site plastic waste separation and working with lower South Island construction sites to record the data from collected plastics, including the amount that was sent to recyclers. Three construction sites in Dunedin were selected through collaboration with a nationwide construction company. The research team provided training, signage and bags for these sites and monitored their progress from September 2023 to May 2024. There are very few options available for the recycling of construction plastics in the lower South Island. Recycle South (Invercargill) is one of these options capable of recycling high-density polyethylene (HDPE), low-density polyethylene (LDPE), expanded polystyrene (EPS) and shrink wrap (at time of research programme). The other major plastic recycling operations are in Canterbury, where Aliaxis (through Comspec and RX Plastics) accept LDPE, HDPE, PVC pipes and PP. EPS Foam Christchurch is another recycler that accepts both EPS and extruded polystyrene (XPS).

A key challenge to sustainable waste management is the transportation of sorted waste materials from construction sites to recyclers. With recycling facilities spread sparsely across the country, waste often needs to travel long distances. Currently, many train carriages return empty from the South Island to the North Island, creating an opportunity to backload these carriages with waste materials. Plastics are ideal for backloading as their small mass has minimal impact on a train’s energy consumption, especially when using containers that would otherwise be empty.