The Toowoomba Regional Council (TRC) is undertaking a $5.3 million project to extend the life of the Toowoomba Waste Management Centre landfill in Toowoomba, Queensland. Specialist Brisbane firm DECC Environmental has started work on the project with support from Toowoomba civil engineering firm Harrison Infrastructure Group.
TRC Water and Waste Committee portfolio leader Cr Nancy Sommerfield says work on the second vertical expansion at the landfill has begun. It is scheduled to be completed in the first half of 2023. Vertical expansion includes the construction of a fully lined and engineered landfill cell above previously filled cells. The expansion can be likened to “piggy-backing” on the existing filled waste cells. The project involves multiple liners within the cell, essentially like a giant bin liner, above a drainage aggregate layer containing the leachate system that is designed to capture any liquid in leachate tanks. Nineteen-thousand tons of clay and 2900m³ of gravel and rock (for the drainage layer) all sourced from the Harlaxton quarry would be used in various earthworks.
“Vertical expansion above an existing and completed landfill cell was identified as the most cost-effective and efficient method to meet our more immediate needs and comply with environmental requirements,” Sommerfield says. “Making the best use of space at landfills means the vertical expansion works within the confines of the current landfill footprint.”
The new cell will add around 240,000m³ of airspace, which adds up to three years to the landfill life before another cell will be needed. “Residents’ willingness to divert as many materials as possible from the general waste bin or when visiting the Greater Toowoomba Waste Management Facility means we are reducing the volume of material that ends up in our landfill, in line with Queensland government waste reduction targets,” Sommerfield continued. “Successfully achieving Queensland’s ambitious waste diversion targets can help extend the life of the landfill even further. This has cost savings for council and ratepayers, while also improving our environmental outcomes.”
This second vertical expansion project is part of a progressive, six-stage expansion planned at the site over 20 years on the current landfilling footprint. Work on stage one, which was the first vertical expansion project in Australia, was completed in late 2017. Expansion to the west of the existing landfilling operation at the Hermitage Road site has the potential to extend the life of the facility by more than 50 years.
“Maximizing landfill space by vertical expansion and extension onsite to the west is far cheaper than establishing landfilling operations at a new landfill site and offers better environmental safeguards,” Sommerfield added. “In addition, the new cell has wells installed which will collect the gas produced by the breakdown of organic waste. The gas is collected and used in our innovative project, in conjunction with Queensland firm LGI, to supply up to 50% of the power to run the nearby Wetalla Water Reclamation Facility via a 1,000 kilowatt gas-fired generator.”