White spill: Life cycle assessment approach to managing marine EPS litter from flood-released pontoons

The South-east Queensland rains and Flooding Event of February–March 2022 was caused by prolonged, severe rains which caused fatalities, destruction of houses, businesses, and transportation systems and infrastructure, and led to the environmental catastrophe known as the “White Spill” event. Extreme volumes of marine debris flowed into open water across the Eastern Seaboard of Australia as flood waters began to drain from the inundated landmass. The force of the floodwaters dislodged and damaged infrastructure including marine pontoons from river systems and marinas.

37 pontoons, weighing in excess of 16 tonnes each, subsequently disintegrated along a 250-kilometre stretch of coastline, from Mulgumpin (Moreton Island) northeast of Brisbane, across Noosa Eastern Beaches and Northern Shore, to K’gari (Fraser Island) expelling their large volume of polystyrene contents into the globally recognised and highly sensitive coastal ecosystems of the Southern Queensland. A further 300 pontoons were reported by Maritime Safety Queensland to have been retrieved from open water with an unknown number lost or sunk during the event. The presence of polystyrene poses significant challenges for environmental clean-ups due to its fragility, buoyancy and toxicity with long-lasting impacts on marine and coastal wildlife.

We are excited to see this work through Tangaroa Blue Foundation’s collaboration with Ten Little Pieces and researchers at RMIT University and CSIRO’s Ending Plastic Waste Mission, a life cycle assessment (LCA) approach on how to manage polystyrene from pontoons was conducted.

This study highlights that at present, the standard end-of-life recommendation for pontoons, regardless of if they were flood debris, is to send them to a landfill. This poses a challenge as polystyrene-containing pontoons can take up large amounts of space in landfill due to their volume and thus shorten the lifespan of the landfill. It can also break up into microplastics that can disperse from landfill and chemical leaching into the surrounding environment can occur.

Alternative methods for end-of-life include chemical solvent application, such as d-limonene or acetone, and mechanical recycling. This study found that chemical dissolution using d-limonene was the most environmentally favourable option, followed by mechanical recycling and then landfill. However, none of these alternative methods are commercially available at the scale required to handle pontoon debris in Australia. Mechanical recycling of clean polystyrene dropped off at collection depots is available, however, polystyrene collected from the “White Spill” event was not clean and could not be recycled. Ultimately this study highlights the end-of-life disposal should not take priority over waste avoidance. Instead, alternative materials for pontoon production should be prioritised and improved maintenance and care of existing pontoons should be regulated and enforced.

Read the full paper here

Published by