During 2017–2018, Cerqueira evaluated the use of source separation for the recovery of construction waste on an active new-build construction site.[1] The site chosen was a residential development of approximately 350 m² floor area in Auckland. Among other construction materials, approximately 80 kg of mixed plastics were able to be separated into soft and hard grades and sent to Visy recycling or Mitre 10 to achieve 100% diversion. In this case study, of the 6.8 tonnes of waste audited, a total of 4.1 tonnes were diverted from landfill representing 60% waste recovery and diversion. However, contractors have indicated to Green Gorilla that separation at source is not sustainable due to the time required (and costs incurred as a consequence).

An exploratory study is underway at Unitec to identify and quantify plastic waste streams, and their potential for recycling, from new-build construction. The study will inform a broader national study of the potential for diversion, of all materials, within the new-build and deconstruction sectors, including the economic implications of a range of models for construction waste processing with a medium-term goal to provide economic and sustainable alternatives to landfilling.

This study measures the waste product of the new build process, but does not measure the waste from construction demolition.

An example of the types of plastic pipes used in construction.

Approximately 80 kg of mixed plastic waste was generated from a residential development of 350m² floor area in Auckland

[1] Cerqueira, I.B.S. (2018). Waste Recovery and Landfill Diversion by Source Separation on an Active Construction Site. A final year project report MG7101, submitted in partial fulfilment of the requirements for the Degree of Bachelor of Engineering Technology (BEngTech, Civil), Unitec Institute of Technology (unpublished)

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