Wollondilly Council’s strategy to minimise disposal costs for spoil material generated from roadworks has already generated millions of dollars in savings, a report to April’s Council meeting has highlighted.

The report demonstrates not only that Council has a solid strategy to minimise disposal costs as much as possible but also that its strategy of reduction, recycling and disposal has generated savings of over $31 million dollars over the past three years when compared with commercial landfill disposal.

The good news was delivered in response to a resolution at the October 2022 Council meeting requesting a report on the costs of dumping excess soils and other waste in association with road maintenance, reconstruction, roadside drainage works, road verge works and works in the road reserve including footpaths for the previous three years.

Mayor Matt Gould noted. “Our community rightly wants Council focussed on making the most of our limited funds so we can invest as much as possible in road repair. I’m very pleased that this report shows our excellent staff are delivering, saving millions of dollars every year by recycling and reusing our roadwork spoil.”

“The recycling and disposal of spoils makes up approximately 10% of our spoil-generating roads and drainage expenditure, with our great Infrastructure Operations and Waste and Environmental Services teams working together to squeeze every saving they can to reduce this expenditure.”

“Given the regulatory, operational and logistical constraints associated with spoils, I’m confident that the current approach is the most economical means of managing this waste stream.”

The report explained that the composition of spoil material varies depending on the type of work undertaken. For example, when removing the top layer of a pavement surface in preparation for re-surfacing, the material generated is generally of a high quality and can be reused in other Council road maintenance works.

This material is stockpiled in various locations across the Shire for use in the short to medium-term future. In this case, the only cost is in the transport to and from the stockpile location.

During heavy patching and reconstruction operations where the full depth of the pavement is excavated, a mixture of bitumen, gravel and clay is generated. This material would usually be sorted, with the gravel and bitumen reused and the clay stockpiled for later collection and processing by a recycling company.

The material extracted from drainage and verge works is a mixture of clay, silt, organics and contaminants from litter including hard and soft plastics and glass. Despite significant investigations, the limited end-use for this material and the high processing costs make recycling this material economically unviable, and so it needs to be landfilled.

The Protection of the Environment Operations Act 1997 provides for the NSW Government to charge licensed landfill operators a ‘contribution’ or ‘levy’. Landfill operators are required to collect the levy as part of their gate fees to customers, and pass it on to the NSW Environment Protection Authority, in a similar way that suppliers charge GST which they pass on to the Australian Taxation Office.

The landfill levy rates are divided into three categories, determined by the location of the landfill. Wollondilly Shire is in the fortunate position to fall within the Regional Levy Area and because Bargo Waste Management Centre does not accept waste generated from outside the Shire, the facility pays the rate of $87.30 per tonne for all material that is landfilled.

Council is required by the EPA to pay the levy even for material that is generated by its own internal operations including roadworks, despite the fact that Council owns Bargo WMC.

Council’s first priority is to internally reutilise materials generated during construction and maintenance work on other sites and projects occurring in the road reserve.

Council contracts a number of companies to collect and/or process recyclable spoils. Recycling composite materials involves a complex process of running the materials through rotating drums, shakers, screens, blowers and conveyor belts to separate the various components. The companies’ infrastructure and mobile plant is designed and configured to recycle high volumes of this material.

Spoils generated by Council’s infrastructure operations that are unable to be reused or recycled are disposed of via landfill at Bargo Waste Management Centre (WMC). For spoils requiring landfilling, it would be economically unviable for Council to consider a facility other than Bargo WMC.

Across Australia, the practice of stockpiling spoils on road reserves has come under the heavy scrutiny of each state’s respective environmental compliance authorities. While stockpiling for reuse in the short-term future is acceptable, Council must be able to demonstrate that the material is able to be reused in the anticipated timeframe.